1,248 Matching Annotations
  1. Jan 2022
    1. the 26°C-specific expression of Kdm6b began in T. scripta gonad-mesonephros complexes as early as stage 13, before the gonad was distinct

      The authors tested the abundance of KDM6B RNA (denoted as Kdm6b) in turtle embryos at the earliest stages of sex development (stages 12-14) to see if there was a difference between males and females.

      The gonad-mesonephros complexes are the earliest sites of gonad development.

    2. This sexually dimorphic expression profile was maintained in gonads throughout the temperature-sensitive period (stages 15 to 20)

      The authors compared Kdm6b gene expression between gonads at male and female temperatures throughout the temperature-sensitive stages of development (stages 15-20).

  2. Dec 2021
    1. the feedbacks of those temperature changes to chemical processes

      While the chem-only simulation is intended to determine the effect of chemistry on ozone depletion, it cannot fully capture this effect because the chemical reaction rates also depend on temperature.

      As the amount of ozone changes, the atmospheric temperature also changes.

      If these temperature-driven variations in chemistry were fully accounted for, the effect of chemistry on ozone depletion could be even larger.

    2. a volcanically clean simulation (vol-clean), considering only background sources of stratospheric sulfur

      This approach only includes sulfur-based aerosols that did not originate from a volcanic eruption.

      Thus, the effect of the volcanic eruption on ozone depletion is removed.

    3. a simulation encompassing observed time-varying changes in temperature and winds from meteorological analyses, with calculated background and volcanic stratospheric particles as well as other types of PSCs (chem-dyn-vol)

      In this approach, the primary contributors to ozone depletion are included in the model, and it is expected to be the closest to the actual measured trends.

    4. full chlorine and bromine chemistry

      The human-made substances that are primarily responsible for the hole in the ozone layer are chlorine- and bromine-based chemicals.

      Thus, chemical reactions involving chlorine and bromine are included in the model to simulate the ozone depletion process.

    5. The year 2002 was anomalous in terms of meteorological behavior in the Antarctic (29), and it is excluded from all trend analyses throughout this paper.

      The goal of this paper is to determine if the reduction in human-made ozone-depleting chemicals is healing the hole in the Antarctic ozone layer. It studies ozone-layer trends over the time period of 2000 to 2015. However, in the year 2002, the Antarctic weather conditions were unusual compared to other years within this time period.

      Since ozone depletion in the atmosphere is extremely sensitive to weather conditions, the year 2002 was not included in this analysis.

    6. The modal submodel calculates variations in stratospheric aerosols from volcanic sources

      Here, modal refers to the aerosols in the atmosphere which have a distribution of sizes.

      The size distribution used in this model includes 3 modes corresponding to smaller (Aitken), intermediate (accumulation), and larger (coarse) diameter aerosols. Read more here: https://www.dwd.de/EN/research/observing_atmosphere/composition_atmosphere/aerosol/cont_nav/particle_size_distribution_node.html

    7. We used the specified dynamics option, SD-WACCM

      A specified dynamics model incorporates actual temperature and wind measurement data.

      This approach improves the specified dynamics model's accuracy compared to a model which does not include measured data.

    8. Model calculations were carried out with the Community Earth System Model 1 (CESM1) Whole Atmosphere Community Climate Model (WACCM)

      The CESM1 version of this model includes effects which extend from the Earth's oceans to the second-highest layer of the atmosphere (thermosphere). This allows for a more accurate representation of how different parts of the Earth's climate system influence the ozone layer.

      In addition, the model accounts for how the climate system interacts with chemical reactions in the atmosphere. This is important for modeling how chemicals deplete the ozone layer.

      The model can be used to calculate historical ozone trends and to make predictions about future trends.

    9. balloon ozone data from the Syowa and South Pole stations

      Balloon ozone data is collected by attaching an ozone-measuring device to a balloon that carries the device into the atmosphere. As the device travels through the atmosphere, it transmits data back to the ground station. Read more here: https://gml.noaa.gov/ozwv/ozsondes/

      The Syowa Station is a Japanese research post in the Antarctic which collects data on atmospheric ozone as well as other scientific data. Read more here: https://www.nipr.ac.jp/english/antarctic/center.html

      The Amundsen–Scott South Pole Station is a research site in the Antarctic administered by the United States' National Science Foundation. The station collects a variety of scientific data including data on atmospheric ozone. Read more here: https://www.nsf.gov/geo/opp/support/southp.jsp

      See animations of yearly South Pole Station ozone data here: https://gml.noaa.gov/dv/spo_oz/movies/index.html

  3. Oct 2021
    1. Lentiviral treatment of two different shRNAs led to a 73 to 82% reduction of Kdm6b transcripts in 26°C gonads from early stage 15 onward (fig. S4), as compared with treatment with nonsilencing scrambled virus

      The authors validated the shRNAs using multiple methods.

      The shRNA was infected with a fluorescence tag, called green fluorescent protein or GFP. The infected embryos were then visualized at multiple developmental stages. The treated embryos fully fluoresced green, including the gonads, which indicated that the virus successfully introduced the shRNA to the embryos.

      The authors also checked the levels of transcript between the control shRNA- (a non-specific sequence) and Kdm6b shRNA-treated embryo gonads. In the green, GFP+ gonads, the shRNAs specifically reduced Kdm6b by up to 80% when compared to the controls.

    2. Immunofluorescence

      A widely-used technique used to image proteins on or within cells. It uses antibodies to bind and tag a protein of interest.

      The first antibody specifically binds the protein of interest, for example KDM6B. Then, a second antibody carrying a fluorescent dye attaches to the first antibody.

      These proteins are visualized using a microscope with lasers. The lasers excite the fluorophore, which in turn emits specific light waves. Here, the KDM6B is marked by the emission of light waves in the green spectrum and beta catenin produces waves in the red spectrum.

      Here is a brief introduction to immunofluorescence techniques: https://oni.bio/nanoimager/super-resolution-microscopy/immunofluorescence/

    3. Knockdown of Kdm6b at 26°C led to a significant increase in H3K27me3 levels within the Dmrt1 locus, without altering histone H3 occupancy

      When Kdm6b was lost, histone methylation was higher at the Dmrt1 locus than the control at MPT. This indicates that H3K27me3 may mediate Dmrt1 expression at MPT.

    4. Consistently, the enrichment of H3K27me3 in the promoter region of Dmrt1 was significantly higher at 32°C than at 26°C

      H3K27me3, which is associated with silenced transcription, was more abundant at the Dmrt1 promoter at FPT compared to MPT gonadal cells.

    5. Knockdown of Kdm6b reduced KDM6B binding to the promoter of Dmrt1 in gonadal cells

      Authors saw that KDM6B was no longer binding to the activating sites for Dmrt1 in developing Kdm6b-knockdown gonadal cells at MPT. The reduction almost brought KDM6B association with the Dmrt1 promoter to that observed in gonads at FPT.

    6. KDM6B is strongly recruited to the promoter region of Dmrt1, with higher enrichment at 26°C than at 32°C

      KDM6B protein occupies the key transcriptional activation site at DMRT1 in gonads at MPT compared to FPT.

    7. Knockdown of Kdm6b increased the total level of H3K27me3 in gonadal cells at 26°C

      Depletion of Kdm6b, which encodes a histone lysine demethylation enzyme, causes overall H3K27 trimethylation levels to increase at MPT.

    8. Immunofluorescence analysis revealed that H3K27me3 was more highly enriched in gonadal cells at 32°C than at 26°C.

      Cell imaging shows that the histone tail modification, H3K27 trimethylation, is specifically enriched in gonads at FPT over that of MPT.

    9. Male-specific medullar distribution of germ cells was observed in the rescued gonads, although some germ cells remained in the cortex

      The Kdm6b-depleted + Dmrt1 overexpression gonads demonstrated primarily male germ cell composition and structure at MPT.

    10. SOX9 protein was robustly activated in the primary sex cords of Kdm6b-deficient 26°C gonads overexpressing Dmrt1 (Fig. 3D), and the Kdm6b knockdown–induced reduction of Amh and the up-regulation of the female markers Cyp19a1 and Foxl2 were all reversed (fig. S13)

      Dmrt1 overexpression was able to restore presence of male sex development marker SOX9 in Kdm6b-depleted gonad germ cells.

      Conversely, Dmrt1 overexpression also reduced the presence of female sex fate genes relative to controls.

    11. Overexpression of Dmrt1 rescued the male pathway of 16 of 18 (88.9%) Kdm6b-deficient 26°C gonads

      When authors increased Dmrt1 in the Kdm6b-depleted embryos at MPT, embryos showed male gonad development.

      In molecular biology, this is known as a "rescue" when addition of a molecule can correct a disrupted system.

    12. Dmrt1 could be a critical target of KDM6B

      Kdm6b is required for the expression of Dmrt1 and is active just before Dmrt1 in MPT development. Thus, authors reason that KDM6B could be required for the activation and function of DMRT1.

    13. Dmrt1 mRNA levels were reduced to ~13% in Kdm6b-deficient 26°C gonads from stage 15 onward (Fig. 3A), and DMRT1 protein was also reduced or absent (Fig. 3B).

      Authors observed that during the peak stages of gonad development, Kdm6b-deficient embryos at MPT also had lowered Dmrt1 RNA and protein levels.

    14. we previously demonstrated that the loss of Dmrt1redirected gonads incubating at 26°C toward female fate, whereas the gain of Dmrt1 redirected gonads incubating at 32°C toward male fate

      In a previous paper, these authors knocked down Dmrt1 like they do for Kdm6b in this study.

      They observed several female gonad features for embryos in MPT that lacked Dmrt1. When they enriched Dmrt1 in embryos developing at FPT, they saw masculinization.

      This indicates that Dmrt1 regulates male gonad development, similarly to how the authors characterize Kdm6b in this paper.

      This lead authors to test if Kdm6b regulates Dmrt1.

    15. Dmrt1 was of particular interest because the early male-specific expression pattern is detected at stage 14

      Dmrt1 is another gene enriched in embryos at MPT. The authors show here that Dmrt1 expression is activated right after Kdm6b at MPT.

    16. exhibited a female-like distribution pattern in the developed outer cortex of Kdm6b-knockdown 26°C gonads

      The gonads lacking Kdm6b at MPT resembled the structure and organization of gonads at FPT.

    17. SOX9 protein was expressed specifically in the nuclei of precursor Sertoli cells in control 26°C gonads, whereas it was sharply reduced or absent in Kdm6b-deficient 26°C gonads

      The male sex fate gene SOX9 was depleted in gonads lacking Kdm6b at MPT.

    18. analyzed the expression

      The authors checked gene expression of male and female sex fate markers in gonads after sex determination across treatment conditions.

    19. To confirm the activation of the female pathway in 26°C embryos with Kdm6b knocked down

      Next, authors wanted to see if the male-to-female sex determination shift could be detected by gene expression of additional important sex-related genes.

    20. Kdm6b-deficient 26°C gonads became elongated

      Embryos incubated at MPT treated with the Kdm6b shRNA developed gonads resembling females, with long and thin structure as opposed to the compact and round male gonads of the control.

    21. Control 26°C embryos treated with the scrambled virus exhibited typical cylindrically shaped testes, and control 32°C embryos displayed typical long and flat ovaries

      It is important to have normal or "wild-type" development processes for comparison to the experimental treatment conditions.

      The authors confirmed here that the control MPT and FPT embryos treated with the scrambled virus develop as expected.

    22. Kdm6b responded quickly to estrogen treatment

      Kdm6b gene expression responded to temperature change and was also sensitive to sex hormone treatment.

      The FPT gonads that were treated with a female sex hormone inhibitor showed similar Kdm6b expression to the male temperature gonads.

    23. significant changes in Kdm6b expression were evident by stage 17, preceding gonadal sex differentiation

      Authors checked the response of Kdm6b gene expression to changes in temperature in the gonads during sex development.

      In the MPT and FPT-to-MPT gonads, authors observed high levels of Kdm6b expression, whereas the FPT and MPT-to-FPT incubated gonads maintained low Kdm6b expression.

    24. We next examined the responses of Kdm6b expression to temperature shifts and sex hormone–induced sex reversal during the temperature-sensitive window

      Now that they have seen that KDM6B is specifically abundant in gonads at MPT, the authors will test if changing temperature or sex hormones will change Kdm6b expression.

    25. In contrast to the ChIP signal at the Dmrt1 locus, no occupancy of KDM6B or H3K27me3 was found in other early sex-biased genes Amh, Cyp19a1, Fdxr, Pcsk6, Nov, and Vwa2

      To see if this H3K27me signature was specific to Dmrt1, the authors also checked other sex-related genes that are expressed around the same time.

  4. Sep 2021
    1. table S4

      The authors used candidate models to characterize the association between control measures and the new confirmed cases.

    2. table S1

      The authors used candidate models to study the association between the Wuhan city travel ban and the arrival time of COVID-19 in other cities

    3. we investigated the possible effects of control measures on the trajectory of the epidemic outside Wuhan city

      In the previous sections, the authors have studied the effectiveness of two types of interventions (the Wuhan lockdown and the transmission control measures) individually. In this section, they move on to simulate the transmission patterns if no interventions had been taken, only one of the two types of intervention had been taken, and under the synergetic effect of the two.

    4. By fitting an epidemic model to the time series of cases reported in each province (fig. S3)

      The authors used an SEIR model for the fitting (with more mathematical details presented in the Supplementary Materials). In this model, the entire population is divided into four groups: susceptible (S), exposed (E), infectious (I), and recovered (R). Susceptible people are those who can be infected. People who are infected but have yet to show any symptoms or become infectious themselves are exposed. After the incubation period, the time taken to develop symptoms, people become infectious. Lastly, having beaten the disease and become immune to it, people are recovered.

    5. These results are robust to the choice of statistical regression model

      To confirm the conclusion drawn from the regression, the authors tried a different way of computing the regression coefficient, confidence interval, and P value. The consistency between results derived using two methods indicates that the results present here are robust to the choice of the regression model.

    6. A separate analysis

      With the effectiveness of early interventions in slowing the spread of COVID-19 first demonstrated by the Mann-Whitney U test, the authors further conducted a regression analysis to reveal the association between several factors and the number of laboratory-confirmed cases. You can find more details of the regression in the Supplementary Materials.

    7. P < 0.01

      A P value below 0.01 means less than a 1% chance that the null hypothesis is true. Typically, a P of 0.05 or below suffices to conclude a significant correlation between two variables.

      This probability is derived through a Student's T-test. This test requires the correlation coefficient (r) and the number of samples (n) as inputs.

    8. For comparison

      COVID-19 spread fast. To show this, the authors compared the outbreak data for COVID-19 with those for H1N1, another contagious disease, in China.

    9. We first investigated the role of the Wuhan city travel ban, comparing travel in 2020 with that in previous years and exploring how holiday travel links to the dispersal of infection across China.

      To investigate the impact of the Wuhan travel ban on the spread of COVID-19, the authors first evaluated the effectiveness of this ban on stopping the movement of people.

      The evaluation was realized by comparing the travel data from the year 2020 with those from the previous two years.

      Note that the start and end of the time period of records are fixed with reference to the date of Spring Festival, which, however, varies from year to year.

    10. These data include the numbers of COVID-19 cases reported each day in each city of China, information on 4.3 million human movements from Wuhan city, and data on the timing and type of transmission control measures implemented across cities of China.

      For the quantitative analysis—linear regression in this work— the input data include official reports of the health commission, mobile phone data, and travel information recorded in online databases.

      For details regarding the time span of the data sets and the means of data acquisition, please refer to the first two sections of the Materials and Methods described in the Supplementary Materials.

    11. during the first 50 days of the COVID-19 epidemic in China, from 31 December 2019 to 19 February 2020

      The authors focused on the first 50 days since the detection of the first COVID-19 case in Wuhan. They summarized the timeline for the implementation of key control measures over this period in Fig. 1.

    1. We estimated robustness of animals to the extirpation of plants (assuming bottom-up control) and robustness of plants to the extirpation of animals (top-down control). We simulated two scenarios, one in which order of extirpation was random and another—more extreme—scenario in which order was from the most generalist to the most specialist species. After using a null model correction on each metric to account for variation in sampling intensity and network dimensions across studies (14), we compared the 95% confidence intervals for the O‘ahu networks with the global dataset.

      The authors designed hypothetical scenarios where generalist or specialist species in a network went extinct, then determined the severity of these extinctions by measuring the amount of additional species that would (theoretically) go extinct as a consequence.

      The use of a null model ensures that the results found by these simulations are not a coincidence, that is, not due to chance.

    2. We assembled and analyzed a dataset of 42 avian SDNs encompassing a broad geographical range, with data from islands (n = 17) and continents (n = 25) in tropical (n = 18) and nontropical (n = 24) areas (table S12). Although some of the other SDNs in the analyses included introduced species [e.g., (7, 34)], SDNs on O‘ahu present an extreme case of dominance by introduced species (>50%), coupled with extinction of all native frugivorous birds

      The authors surveyed data from seed dispersal networks across a variety of habitats, noting that O'ahu was unique in that the majority of its population was mostly made up of introduced species, with the original bird species of the island going extinct.

    3. To what extent are introduced species integrated into seed dispersal networks (SDNs), and do introduced dispersers replace extinct native animals? To investigate these questions, we examined interactions based on 3278 fecal samples from 21 bird species [tables S1 to S3 and (13)] collected over 3 years at seven sites encompassing broad environmental variation across Oʻahu (fig. S1 and table S1).

      With the original bird species extinct, how well does the introduced bird species spread the seeds of native plants? Does this newer bird species show a preference toward introduced species of plants?

      To address these questions, the authors collected poop samples over the course of 3 years from 21 different birds found in 7 different locations across the island of O'ahu. The supplemental figure 1 and table 1 describe the 7 locations' average rainfall, coordinates, and elevation to demonstrate the diversity of these areas. Another set of tables listed the different species and plants (introduced and native) found at each site.

    4. The statistical significance of the observed topological patterns was assessed by contrasting observed values for each metric with the confidence interval from null models (13)

      To determine if an observation is a consequence of a measured phenomenon, and not by chance, researchers must test (and reject) the null hypothesis. A null hypothesis states that a result or observation is due to chance, and so should be disregarded as insignificant. When researchers can reject the null hypothesis, that means their results from a study were not due by chance.

      In this case, the authors test the significance of the identified patterns in the network by comparing these values to a null model, a generated collection of values randomized to produce a pattern based on no ecological mechanism (Gotelli and Graves, 1996). If the observed values differ from the range of null values defined by the null model's confidence interval, they are considered significant.

    1. total ozone column measurements from the South Pole station

      Total ozone column data can be obtained by combining balloon data with data measured using satellites.

      Satellites are able to obtain data at higher altitudes than balloons, which are limited to around 30 kilometers.

    2. The historic discovery of the Antarctic ozone hole was based on observations taken in October (1), and healing cannot be considered complete until the ozone hole ceases to occur in that month, which is expected around mid-century (2, 28). However, October need not be the month when the onset of the healing process occurs.

      The earliest October ozone hole measurements are used as a reference for the trends that follow.

      Nevertheless, September and November data can still be used to track the impact human-made chemicals, climate variations, and volcanic eruptions are having on the ozone layer over time.

    3. a chemistry-only simulation

      This approach removes the contributions of climate variation and volcanic eruptions to ozone depletion.

      Thus, only the effects of variations in chemistry would remain.

    4. our modeled post-2005 total stratospheric volcanic aerosol optical depths are estimated to be accurate to within ±40%

      Since aerosols released from volcanic eruptions can also contribute to ozone depletion, the researchers must account for this contribution as accurately as possible.

      To calculate the accuracy of the model, the modeled data is compared to measurement data during the years that volcanic eruptions occurred.

  5. Aug 2021
    1. site-saturation mutagenesis

      M100 is the specific amino acid residue within the protein sequence that has been identified to be critical for the protein’s function. it is very important to determine the ideal amino acid residue for this position. Site saturation mutagenesis is employed.<br> Site-saturation mutagenesis is a form of random mutagenesis, allowing the substitution of a specific amino acid site with one of 20 possible amino acids in a single experiment. In this study, this technique is employed to generate a series of enzymes with enhanced activity and enantiospecificity.

    2. Carbon–silicon bond formation catalyzed by heme and purified heme proteins.

      Heme proteins that were readily available were screened to identify the one that gave the highest enantioselectivity. This served as a starting point for directed evolution. Purified heme protein, silane, diazo ester, thiosulfate, methyl cyanide and M9-N buffer as the medium for microbial growth were stirred at room temperature in anaerobic conditions. Reactions were performed in triplicate. Unreacted starting material was obtained in all cases and no further purification was carried out.

    1. qRT-PCR analysis showed that expression of Amh and Sox9 sharply decreased, whereas expression of Cyp19a1 and Foxl2 significantly increased in Kdm6b-deficient 26°C gonads relative to controls

      Analysis of the sex fate gene expression showed that male markers were significantly decreased, whereas female markers were significantly increased in Kdm6b-RNAi treated gonads compared to controls.

      Kdm6b-depleted gonads showed marker expression similar to the female control.

    2. two independent experiments with different shRNAs showed that 39 of 45 (86.7%) and 45 of 56 (80.4%) Kdm6b-knockdown embryos displayed a complete male-to-female shift in sexual trajectory at 26°C

      A robust ratio of the Kdm6b-depleted embryos demonstrated a shift from male to female development, despite incubation temperature. This structural data suggests that KDM6B plays an important role in sex determination.

    1. r = 0.69

      We need to take r values with caution, though. Calculating r values is still possible even for plots where two variables are not linearly associated. It is always wise to look at the scatter plot an r corresponds to.

      In the present study, the scatter plot in Figure 2C indeed shows a clear linear association.

    2. the effectiveness of travel restrictions and social distancing measures in preventing the spread of infection is uncertain.

      The present work addressed this question by studying how the spread of COVID-19 was impacted by the travel bans and the closure of entertainment venues. The travel bans encompass the one for Wuhan city and the suspension of inter- and intra-city public transport.

    1. Although the majority of RNA fragments were extremely short (<30 nt), the authenticity of the sequences could be validated

      Given the results demonstrated by Smith and colleagues, the authors decided to look at the size distributions and damage profiled of the RNA recovered from the lung tissue. They found fragments of much greater lengths than 30 nucleotides with fragments ranging from 217-233 nucleotides. They also found no evidence of RNA damage indicating formalin-fixed specimens could serve as a source of well preserved RNA molecules.

    2. mapped to a MeV genome

      These authors took the collection of overlapping DNA fragments produced through sequencing and lined them up to a genome of measles that had already been constructed.

  6. Jul 2021
    1. Fig. 2 Scope of Rma cyt c V75T M100D M103E-catalyzed carbon–silicon bond formation.

      Rma cyt c V75T M100D M103E shows excellent enantioselectivity and turnover over a wide range of substrates. Silicon substrates with weakly electron-donating or -activating methyl substituents (4), strongly electron donating -OMe (5), weakly deactivating -Cl (6), strongly deactivating -CF3 (7), and moderately deactivating COOMe and CONMe (9 and 10 respectively) show moderate to excellent turnover and high selectivity. No direct relationship exists between turnover number and substituent effects from this study. Enantioselectivity is excellent in all substrates. All products were identified using GC-MS, and no traditional organic chemistry techniques were used.

    2. In addition, diazo compounds other than Me-EDA could be used for carbon–silicon bond formation

      Additional diazo compounds that were successful were R3 = -CH3, -CH2CH3, -Ph.

    3. silicon and diazo reagents

      General method for the preparation of phenyl dimethyl silanes: In a 100 mL round bottom flask, chlorodimethylsilane in THF was cooled to zero degrees. A solution of the appropriate Grignard reagent was added dropwise over ~15 minutes. The reaction was allowed to reach room temperature and stirred for ~8 hours. The product mixture was quenched with ammonium chloride solution. The product was extracted into ether and then isolated. Purification was done by column chromatography.

    4. Relative to the wild-type protein, the evolved triple mutant catalyzes the reaction more than seven times faster, with turnover frequency (TOF) of 46 min–1 (Fig. 1E).

      Via site-saturation mutagenesis, V75 and M103 positions along the protein sequence were identified as likely beneficial mutations and were randomized, i.e., the amino acids at these positions are replaced by random ones. A large number of random variants, which together constitute a library, are produced and then screened in an attempt to discover a highly active variant among them. The evolved triple mutant fits the bill.

    5. a 12-fold improvement over the wild-type protein (Fig. 1D).

      Recombinant protein is a protein encoded by a gene that has been cloned in a system that supports expression of the gene (in this case, it is M100). Modification of the gene by recombinant DNA technology can lead to expression of a mutant protein. In this study, M100D mutation is more highly activating than the wild-type protein.

    6. Carbon–silicon bond forming rates over four generations of Rma cyt c.

      Turnover frequency for each variant relative to wild-type protein: WT: 1 M100D 2.8 +/- 0.2 V75T M100D 4.6 +/- 0.3 V75T M100D M103E 7.1 +/- 0.4

      From this experimental data, it is clear that directed evolution has resulted from changing the enzyme from unselective wild-type into a highly enantioselective variant.

    7. using lysates of E. coli expressing Rma cyt c

      Experiments were conducted with purified heme protein, silane, diazo ester, sodium dithionate, MeCN, and M9-N buffer at room temperature in anaerobic conditions for 1.5 h. Three trials were conducted. Turnover number reported is the average of the three trials. Unreacted reactants were not isolated.

  7. Jun 2021
    1. We calculate that 275 million metric tons (MT) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 million MT entering the ocean.

      The range of 4.8 to 12.7 million metric tons of waste comes from uncertainty in the total amount of waste generated, the amount of that waste that is plastic, and the amount of mismanaged waste that enters the ocean.

    2. Our framework was designed to compute, from the best-available data, an order-of-magnitude estimate of the amount of mismanaged plastic waste potentially entering the ocean worldwide.

      Here the authors restate the goal of their investigation.

    1. To investigate how such changes affect communities, we performed multiscale analyses of seed dispersal networks on Oʻahu, Hawaiʻi.

      The authors visited multiple areas in Hawai'i to study how seeds from plants (originally from the area or recently introduced) were being distributed by invasive birds.

  8. Apr 2021
    1. we injected groups of mice with 2×1062×106<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup></math> wild-type 51BLim10 tumor cells and treated them with anti-CTLA-4 beginning on day 0 as before, or beginning 7 days later

      The authors conducted a new set of experiments to check whether administering anti-CTLA-4 after tumors are detected is as effective as administering it at the same time tumors are introduced. If they are able to successfully treat mice after tumors are already established, then maybe this treatment could work for human patients as well!

    2. Mice that had rejected V51BLim10 tumor cells as a result of treatment with anti-CTLA-4 were challenged with 4×1064×106<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>4</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup></math> wild-type 51BLim10 cells 70 days after their initial tumor injections

      The authors injected the mice which were previously treated with unmodified tumor. If they developed an immune memory, they may be able to clear this tumor even though it is not expressing B7 and they have not been given anti-CTLA-4 antibodies.

    3. injected with 4×1064×106<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>4</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup></math> V51BLim10 tumor cells and left untreated, or treated with anti-CD28

      The mice were split into groups that received different treatment regimens. Two of the groups were untreated or were treated only with anti-CD28 antibodies.

    4. injected with 2×1062×106<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup></math> tumor cells

      The authors decided to check if there is an effect to changing the tumor dose. They halved the dose to 2x10(^6) and had a group of untreated and a group of anti-CTLA-4 treated mice.

    5. the growth of V51BLim10, a vector control tumor cell line that does not express B7

      This set of experiments was conducted with a variant of the same murine colon cancer tumor cells, but this time the tumors did not express B7. Thus the tumors are not able to provide the secondary signal to T cells.

    6. untreated controls

      The authors had a control group of mice which were injected with tumor cells expressing B7-1 molecules but were not treated with any antibodies.

    7. Two groups were treated with a series of intraperitoneal injections of either anti-CTLA-4 or anti-CD28

      The authors injected groups of mice with tumor cells expressing B7-1 molecules. The injections were administered within the membrane lining of the abdominal (peritoneal) cavity. These mice were then treated with two different regimens. One group of mice was injected with antibodies targeting CTLA-4 and another with antibodies targeting CD28.

  9. Mar 2021
    1. Via compression, we connected the insulin tip to a shaft made solely from biodegradable polymers

      Tips are connected to the shaft which consists of very large molecules composed of many repeating subunits.

    2. We also performed a laparotomy followed by a gastrostomy to manually place milliposts into the gastric tissue. These experiments yielded comparable pharmacokinetics and systemic uptake.

      The authors made a surgical incision into the abdominal cavity and performed a surgical operation to make an opening in the stomach in order to manually implant the millliposts into a swine stomach. This shows the drug being taken in at a very similar rate as to when the device was ingested.

    3. To demonstrate that the mass distribution affected self-orientation, we showed that the SOMA oriented in 100% of trials, whereas a device of the same shape made solely of PCL only oriented 50% of the time.

      The weight distribution of the SOMA device out performed devices made solely of PCL showing that weight distribution plays a large role in the ability to self orient.

    4. milliposts were inserted into the submucosa of swine stomach tissue after being ejected from a SOMA with a 5-N spring. The insulin tips reached the same depth as dye injected by a Carr-Locke needle (Fig. 3, D to F and H). To ensure a safety margin on the insertion force, we ejected stainless steel milliposts using 9-N steel springs (k = 1.13 N/mm) into ex vivo swine tissue, and these still did not perforate the tissue

      The authors show that a force of 5 N from the spring allows the milliposts to enter into the tissue of the swine's stomach. They verify that this will be safe by testing a force of 9 N, which is larger than the used 5 N, showing that even a larger force will not cause the tissue to rip or be damaged.

    5. Dissolution profiles in vitro demonstrated complete dissolution within 60 min

      The authors tested in a simulation that the millipost will dissolve within 60 minutes after released, so that it is not staying in the body for too long of a time period after it is released.

    6. Stability studies conducted at 40°C showed that the insulin milliposts remained stable in a desiccated environment for 16 weeks (fig. S6), as compared with 4 weeks of stability for a liquid formulation.

      The authors show that the device can be stored for an extended period of time in a warm, dry environment, as well as a slightly shorter time in a liquid environment. This demonstrates that the device can be safely stored and it will not affect the device.

    7. The optimized SOMA shape outperformed both a sphere and ellipsoid made from the same materials with equivalent masses, volumes, and density distributions in two biologically relevant metrics: orientation time and stability.

      When devices with different shapes but the same equivalent mass, volume and density distribution were compared, the SOMA shape was shown to be better at self orienting. This shows that the SOMA shape performs better than the sphere and ellipsoid shapes.

    8. Raman spectroscopy validated the protein structure of the API after high-pressure exposure

      The authors used a technique to determine vibrational modes of molecules to analyze the chemical structure of the API used after having it put under high pressure.

    9. Additionally, to ensure safety in the case of a millipost misfire or device retention, we dosed six SOMA prototypes with 3-mm-long protruding 32-gauge stainless steel needles at once in swine; in this experiment, we performed x-rays over the course of 9 days and found no evidence of GI obstruction, pneumoperitoneum, or other adverse clinical effects

      In the case that the millipost did not dissolve, the authors used SOMAs with stainless steel needles to test that problem. They concluded that the SOMAs with needles that did not dissolve did not cause blockages in the GI tract, nor pneumoperitoneum, or the presence of air or gas in the abdomen. This means that the SOMAs do not cause GI blockages, or behavioral changes or other adverse effects in the swine model. This is promising news and could mean that the SOMAs would work in a human model.

    10. As tested, the SOMA functioned in vivo only in the fasted state. Animals with food and liquid in their stomachs showed no API uptake when tested with two different SOMAs, but three devices tested in empty stomachs demonstrated successful API delivery

      The SOMAs initially only worked when the stomach was empty, or the fasted state. When the SOMAs were dropped into the stomach where there was food, it would try to inject the insulin, but it would not pierce the stomach wall. When there was water, it pierced the stomach wall, but there was no insulin in the bloodstream.

    11. Compression tests measured a Young’s modulus of 730 ± 30 MPa, like that of PEO, and an ultimate strength of 20.0 ± 0.7 MPa, ensuring millipost integrity after external force

      The authors tested how much pressure could be put on the milliposts, which gave the stiffness of the material to be 730+/- 30 MPa. The maximum pressure the material can withstand before breaking is 20 +/- 0.7 MPa. These numbers are used to make sure a pressure higher than that is not used, ensuring the milliposts will stay intact.

    12. We compared these experiments to swine dosed with SOMAs designed to localize the milliposts to the stomach wall without inserting them into the tissue (n = 5). These swine experienced no insulin uptake or blood glucose–lowering effects

      The authors tested the device being ingested, but without the milliposts being inserted into the stomach tissue. No insulin was released, demonstrating that insulin will not leak out of the device without it being implanted in the tissue.

    13. Additionally, we showed the potential for sustained-release delivery by subcutaneously implanting milliposts loaded with 1 mg or greater of API. These milliposts released API with a near zero-order rate for at least 30 hours

      The authors tested how the milliposts would perform with an increased amount of API loaded in it. The device showed that even with more API in it, the drug would be delivered at a constant rate and would continue to be administered for 30 hours.

    14. Milliposts from these experiments released drug at a near zero-order kinetic rate

      The release of the drug was shown to be near constant, independent of the concentration that was being released.

    15. We administered milliposts loaded with 0.3 mg of human insulin to swine and measured blood glucose and API levels. Endoscopically dosed SOMAs localized to the stomach wall and self-oriented before injecting milliposts into the tissue. Histology confirmed that the SOMA delivered milliposts through the mucosa without injuring the outer muscular layer of the stomach

      The authors test the device in a swine stomach. The device successfully found its way to the wall of the stomach and was able to stand itself up in the correct direction and insert the post into the tissue, without causing any damage.

    16. simulations and in vitro experiments, we demonstrated that sucrose dissolution could be tuned to release a compressed spring at a predicted time with a precision of 11.4 s throughout a 4-min time period

      The authors show that the spring has a high precision, so that the time that the spring will actually be released can be very accurately estimated.

    17. Using a custom stage, we demonstrated that milliposts displaced in vivo swine tissue by 7 mm when we applied on the order of 1 N of force

      The authors test the relationship between how much force is applied to the milliposts and how deep the post goes into the tissue of the swine.

    18. toxicity experiments in rats. No inflammation or signs of toxicity were observed

      Oral administration of the device in single doses and repetitive doses was not seen to be hazardous to rats.

    19. to produce the low center of mass needed for the SOMA to self-orient.

      A mixture of low and high density materials were used to make the lower portion of the SOMA device.

    20. In vitro studies confirmed that the SOMA oriented most quickly from a 30° and a 135° angle (Fig. 2C). The device did not orient most rapidly between the angles of 45° and 100° in the simulation or at a 90° angle during in vitro experiments because it possessed a corner in this region.

      Experiments confirmed that the device oriented the quickest between the angles of 30° and 135°. The device oriented the slowest between the angles of 45° and 100° or an exact angle of 90°.

    21. When dropped from a series of random orientations, the simulation predicted that the SOMA possessed the lowest mean orientation time.

      When dropped from different angles the simulation predicted that the SOMA device had the fastest average orientation time.

  10. Feb 2021
    1. The liquids can be colored with dyes or pigments and heated/cooled to change the color of the microfluidic networks in the visible and IR spectrum

      To create blue or red dyes, researchers mixed chemical compounds, methylene blue or amaranth, with water. They also used watercolor paints to create other colors. These solutions helped to camouflage their device.

      To change the temperature of the liquids, the researchers would heat or cool them inside an oven or refrigerator before pumping them into the device. This allowed researchers to adjust how the robot is viewed in the infrared spectrum (IR). The IR spectrum reflects the temperature of the emitting body.

    2. pumping colored or temperature-controlled fluids through a network of microfluidic channels

      The researchers pumped fluids through the microchannels, manually with syringes or with the use of syringe pumps.

      Syringe pumps gradually administer, or withdraw, liquid solutions: https://www.chemyx.com/support/knowledge-base/technical-support/chemyx-syringe-pump-work/

      By pumping fluids through the microchannels, researchers could change the color and display of the device.

    3. closely packed microfluidic channels (Fig. 1) or combined microfluidic channels with wider (millimeters to centimeters) channels (fig. S1D) to create features that are indistinguishable from continuous color in the far field

      The researchers created color layers with different sized microchannels to change the appearance of the soft robot. Wider microchannels allowed for larger blocks of color to be observed. Whereas smaller microchannels allow for many sharp edges and transitions to be created.

      They want readers to realize that many different color-layered microchannel networks can be created to alter how the device may be perceived.

    4. once filled, the color layers require no power, have low requirements for volume of fluid (~30 μL/cm2 of surface), and are lightweight (130 mg/cm2 of surface)

      The total volume of the microchannels used in the color layers equates to 0.75 ml, which is similar to a large drop of water. Therefore, they do not require much water to be filled and are lightweight. Once the robot is filled with liquid, via syringe pumps, no further input is needed.

    5. creating a color layer with periodic microfluidic channels filled with colors matched to that environment

      Here, researchers filled only certain microfluidic channels up with a certain color, in order to mimic the background the robot was resting upon. This form of camouflage is called background mimicking. Researchers wanted to see if this soft robot was capable of background mimicking.

    6. In all demonstrations, the colored solutions were prepared manually by the operator

      Researchers mixed different colored dyes together in order to create different colored solutions. Then, they would place these colored solutions into a pump to be administered into the color layer microchannels of the soft robot.

    7. Using a pumping rate of 2.25 mL/min and neglecting the time necessary to fill the tether, a change in color required 30 s

      Here, researchers are filling the color layers up with liquid using a pump. The rate at which liquid is being pumped into the microchannels is 2.25 milliliters (ml) per 1 minute (min). The researchers want to demonstrate that their device can change colors rather quickly and, therefore, show that their device is capable of being used for camouflage.

      Although 2.25ml/min may seem like a slow pumping rate, the total volume of the microchannels used in the color layers equates to 0.75 ml, which is similar to a large drop of water. Therefore, it is very reasonable for the microchannels to be filled in 30 seconds (s) with a pumping rate of 2.25ml/min.

      The authors excluded the time it took to fill the “tether” when performing this experiment. The tether is simply the tubing that connects the pump to the microchannel. Liquid travels from the pump, through the tether, and into the microfluidic channel.

      Because researchers only wanted to know the time it took for the microchannels to change colors within the color layers, they excluded the time needed for the tether to fill with liquid.

    1. Mechanical and chemical characterization studies on the milliposts supported insulin stability.

      The authors tested the mechanical and chemical properties of the milliposts used to deliver the insulin. The tests concluded that the milliposts would be able to successfully delivery the insulin while keeping it stable.

    2. Our simulation predicted that the SOMA oriented most rapidly between the angles of 0° and 45° and the angles of 100° and 180° measured from the preferred orientation, and it oriented within 100 ms from 85% of all initial positions (Fig. 2B).

      When considering the preferred orientation of the device the SOMA shape was able to self-orient the quickest between the angles of 0° and 45° and the angles of 100° and 180°. This orientation occurs within 100 milliseconds from 85% of all initial positions.

    3. A week after dosing the SOMAs, we performed endoscopies and saw no signs of tissue damage or abnormalities from the stomach injections. Veterinary staff monitored the swine twice daily and saw no signs of distress or changes in feeding and stooling patterns after administration.

      The authors used a scope and looked at the G.I. tracts of the swine that were fed the SOMAs. There were no visible signs of damage from the SOMAs and there was no evidence that these devices were hurting the swine based off of their behavior, eating habits, and the regularity of the excretion of their feces.

    4. To aid in protecting the SOMA from gastric content, we developed a valved membrane insert (fig. S12). As tested in vitro, the valve prevented food particles and viscous liquids from clogging the actuation pathway while still allowing the millipost to pass through.

      The authors designed a membrane that would stop food and fluid from getting into the millipost chamber, keeping the insulin safe, but would allow the millipost to be pushed through the membrane when the spring was activated.https://imgur.com/ncl6OiG

    5. Integrity of the SOMA after GI transit was confirmed by examination of SOMAs recovered after excretion (see supplementary materials and methods).

      Here the authors gave 3 swine 3 SOMAs each and after the swine pooped them out, they examined them for visible damage. The authors said eight of the nine SOMAs were recovered and the ninth SOMA was accidentally disposed by accident during a cage cleaning. This showed that the SOMAs do not cause G.I. blockages, which means that they are safe to ingest.

  11. Jul 2020
    1. We genotyped a diagnostic SNP for the HMGA2 locus in medium ground finches on Daphne Major that experienced the severe drought in 2004–2005 (n = 71; 37 survived and 34 died) (11).

      To look at the specific finches that experienced the 2004–2005 drought, the researchers genotyped a HMGA2-specific SNP in both survivors and victims (71 total birds).

    2. we genotyped an additional 133 individuals of this species for a haplotype diagnostic SNP (A/G) at nucleotide position 7,003,776 base pairs in scaffold JH739900, ~2.3 kb downstream of HMGA2.

      Lamichhaney and colleagues took a closer look at another 133 birds. Specifically, they investigated an SNP at a certain position in the genome.

      Within the 17 SNPs, researchers knew that the large finches were homozygous (LL in Figure 2D) for one haplotype group and small finches were homozygous (SS) for another haplotype group. However, what was going on with the medium ground/tree finches?

      This particular SNP was shown to be associated with only beak and body size within these medium finches.

    3. we investigated whether the HMGA2 locus is primarily associated with variation in body size, beak size, or both.

      HMGA2 had been identified as a candidate gene, and the SNPs within the 525-kb region within HMGA2 had been located. Therefore, the researchers attempted to see which trait this gene was specifically related to.

    4. scan comparing large, medium, and small ground finches and tree finches (Table 1) identified seven independent genomic regions with consistent genetic differentiation (ZFST > 5) in each contrast (Fig. 2A and table S2).

      Researchers performed pairwise, genome-wide fixation index (see definition in Glossary section) scans across the whole genome. They did this with 15kb windows that were non-overlapping regions.

      The following three comparisons were made: 1) large ground/tree versus medium ground/tree; 2) large ground/tree versus small ground/tree; and 3) medium ground/tree versus small ground/tree.

      A compilation of SNP calls yielded 44,767,199 variable sites within or between populations. The fixation index score ranged from zero (complete sharing of genetic material) to one (no sharing of genetic material).

      Each index value was then transformed into a Z-score, which is simply a measure of how many standard deviations below or above the population mean a raw score is. Further analysis was done if the Z-score of the fixation index was greater than five. See the Supplementary Materials for more information.

    5. We identified 17 SNPs showing high genetic divergence between large and small ground finches and tree finches (FST > 0.8) at nucleotide sites in highly conserved regions across birds and mammals (PhastCons score > 0.8) (Fig. 2C).

      The researchers again calculated the fixation index. However, this time it was only for the variable region (~525-kb in size) that contained the HMGA2 gene.

      Remember, the fixation index score ranged from zero (complete sharing of genetic material) to one (no sharing of genetic material).

      For a good explanation of a SNP, see this video.

    6. We combined these data with sequences from 120 birds, including all species of Darwin’s finches and two outgroup species (15)

      DNA extraction and whole genome sequencing was performed using samples from 60 birds. In addition, 120 bird samples from a previous study (Lamichhaney 2015) were used.

      The sequence reads were analyzed and trimmed using FASTQC software and FASTX software, respectively. To see more specific software used, see the Supplementary Materials

      The researchers used the genome assembly of a medium ground finch as a reference genome. The reads from the samples were aligned to this reference.

    1. RNAi-treated animals were then amputated to assess the role of the silenced genes during regeneration

      Once the silenced genes were introduced to the planaria via diet, amputations were conducted.

    2. RNAi of a single β-catenin (Smed-βcatenin-1), both dishevelled homologs (Smed-dvl-1;Smed-dvl-2), or APC (Smed-APC-1)

      Each of these proteins were silenced individually using RNAi and then incorporated into a food source for planarians. The experimental group was divided into three and each was fed one type of the RNAi food for 8 days. Amputations were then completed on all experimental animals on Day 9.

    3. Anatomically, two organ systems with characteristic asymmetries along the A/P axis were examined: (i) the central nervous system (CNS), composed of two anterior cephalic ganglia (brain) and two ventral cords projecting posteriorly (Fig. 1G), and (ii) the digestive system, consisting of a single anterior and two posterior gut branches (Fig. 1K)

      To identify anatomical characteristics that follow an anterior/posterior axis position (head vs tail), the researchers looked at two organs - the primitive brain and the primitive spinal cord of the planaria . This is important to determine, because it allows researchers to identify which molecules direct cells to become a certain cell type as well the molecule that directs the cells to their respective locations in the body.

    4. We cloned and determined the expression patterns of all identifiable homologs of core pathway components (Fig. 1A) and silenced them, individually or in combinations, on the basis of likelihood of redundancy as gleaned from the expression data (figs. S1 to S6 and table S1).

      In this initial part of the experiment, the researchers identified the components of the Wnt signaling pathway found in S. mediterranea and made copies of the genes. Then, using RNAi, each component was silenced individually, and then was silenced in selected groupings to determine the role of each chemical and whether there was overlap in their functions. RNAi was fed to the planaria to introduce the silenced protein.

    5. After head and tail amputations of control worms

      In a controlled experiment, there are two groups: 1) one is controlled, which means that all conditions are held constant or the same and 2) experimental group, in which a defined variable is changed. In this case, the experimental group was treated with RNAi, while the control group was not. This allows scientists to compare the two groups to determine if what they changed in the experimental group was due to that variable.

    6. planaria, we analyzed the canonical Wnt signaling system in Schmidtea mediterranea

      The goal for this series of experiments was to better understand the Wnt signaling system because it is found many animal species ranging from invertebrates to vertebrates. The Wnt signaling system is a pathway found in most animal species. It is one of the most important cell signaling systems because of its control over how and when cells divide, change into specific cell types, and move to the area of the body that they belong during embryonic development. This includes directly how stem cells allow for renewal of damaged tissues.

      You can find more information on this pathway here: https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/wnt-signaling-pathway

    1. an array of measures ranging from rotational behavior (Fig. 6D) to head position bias and locomotion

      Motor behavior was assessed using amphetamine-induced rotations, head position bias, and locomotion.

      Rotations were performed by injecting amphetamine 30 minutes prior to trial and placing the animal in an opaque cyclinder. Ipsilateral (same side as) rotations to the 6-OHDA lesion (clockwise) were added and contralateral (opposite side as) rotations were subtracted.

      Head position bias was determined by the number of head tilts over time, where a greater than 10 degree deviation left or right from midline was measured.

      Locomotion was measured using software called Viewer that tracked motion and calculated distance.

    2. Therefore, optogenetics, in principle, could be used to systematically probe specific circuit elements with defined frequencies of true excitation or inhibition in freely behaving parkinsonian rodents.

      This group has led the field of optogenetics by laying the groundwork for how this "tool" can be employed in neuroscience research.

    3. based on single-component microbial light-activated regulators of transmembrane conductance and fiber optic– and laser diode–based in vivo light delivery

      Opsins are transmembrane proteins (passing through the cell membrane) that are ion channels/pumps which allow for various ions like sodium, potassium, hydrogen, chloride, and calcium to move in or out of the cell.

      There are three main families of opsins: channelrhodopsins, halorhodopsins, and bacteriorhodopsins. Each opsin is light sensitive due to a chromophore retinal molecule within the transmembrane domain of the channel, and each family is sensitive to a specific wavelength of light.

    4. To inhibit the excitatory STN neurons directly, we delivered lentiviruses carrying eNpHR under the CaMKIIα promoter to the right STN of the hemiparkinsonian rats. CaMKIIα::eNpHR labeled with enhanced yellow fluorescent protein (EYFP) expression was specific to excitatory neurons

      Second-generation lentiviruses encoding the enhanced halorhodopsin were created using three plasmids.

      One plasmid containing the gene of interest (eNpHR) under the control of the promoter (CaMKIIα) is called the transfer vector. The transfer vector usually encodes a fluorescent gene to monitor expression: in this experiment, enhanced yellow fluorescent protein (EYFP) was added after the eNpHR sequence.

      A second plasmid containing the envelope gene, usually VSV-G (vesicular stomatitis virus), allows for a broader degree of infectivity in various cells. The third plasmid contains all of the packaging genes necessary to create a functional viral unit.

      When all three plasmids are added to HEK293 (human embryonic kidney) cells, viral particles are released from the cells and suspended in the culture media. Learn more about lentiviruses here.

    5. Because simple inhibition of excitatory cell bodies in the STN did not affect behavioral pathology and because HFS (90 to 130 Hz) is used for electrical DBS, we used ChR2 to drive high-frequency oscillations in this range within the STN.

      Since inhibiting excitatory neurons in the STN with eNpHR and activating glial cells with ChR2 were both insufficient at correcting motor deficits in hemiparkinsonian rats, the authors attempted to mimic the high-frequency stimulation using ChR2 in the excitatory neurons.

    6. Therapeutic effects could arise from driving axonal projections that enter the STN

      In other words, beneficial effects could arise by activating or targeting axonal projections entering the STN as opposed to direct STN interventions.

    7. optogenetics allows genetically targeted photosensitization of individual circuit components

      The specificity of optogenetic treatments is of particular clinical interest and relevance for neuroscientists. Because individual cells can be targeted in the living organism, optogenetics allows scientists to better understand how different brain cells function and communicate.

    8. hybrid optical stimulation–electrical recording device (optrode)

      An optrode is a combined optical fiber with a metal electrode that can both stimulate via light and record via a tungsten wire. The tungsten wire was tightly attached to the optical fiber with the electrode tip being slightly deeper to ensure proper recording from light-stimulated neurons.

    9. S100β staining

      S100β, also known as calcium-binding protein B, is expressed by mature astrocytes. S100β can also be used as a peripheral biomarker of blood-brain barrier permeability.

    1. in-class exams

      The main way the authors assessed student performance was to compare scores on multiple-choice exams. These scores are referred to as the main outcome measure.

    2. In this randomized double-blind study

      The authors used a double-blind study design, meaning that neither the students nor the teaching assistants working with the students knew the purpose of the study, or to which group each student was assigned. Double-blind studies are meant to reduce unintentional bias on the part of the participant or the researcher interpreting the data.

  12. Jun 2020
    1. We therefore used the anterior and posterior markers to investigate the onset of blastema differentiation in control and RNAi-treated trunk fragments (Fig. 2, A and B).

      With the knowledge from the previous experiment that regulation of β-catenin occurs earlier in the Wnt signaling pathway, the researchers were able to use the anterior/posterior markers to identify the time period during which the stem cells of the blastema differentiated in both the control and experimental animals.

    2. We next used animals silenced for both Smed-βcatenin-1 and Smed-APC-1 to test whether the Smed-APC-1(RNAi) phenotype results from increased β-catenin activity.

      In this set of experiments, Alvarado and colleagues were trying to identify if increased amounts of β-catenin regulates that expression of Smed-APC-1.

    3. We then explored whether the β-catenin switch plays a role in blastema identity regardless of the A/P location or angle of amputation. Indeed, the head fragments of Smed-βcatenin-1(RNAi) and Smed-dvl-1(RNAi);Smed-dvl-2(RNAi) worms regenerated a head from the posterior wound (penetrance = 79%, n = 24; penetrance = 82%, n = 33, respectively), and the tail fragments of Smed-APC-1(RNAi) worms regenerated a tail from the anterior wound (penetrance = 67%, n = 27; Fig. 3, A to E, and movie S4). After longitudinal amputation along the midline, control animals formed a blastema along the A/P axis and regenerated mediolaterally (Fig. 3, F, J, N, and R). In contrast, Smed-βcatenin-1(RNAi) and Smed-dvl-1(RNAi);Smed-dvl-2(RNAi) worms regenerated anterior tissue and developed multiple ectopic heads along the lateral edge (Fig. 3, G, H, K, L, O, P, S, and T).

      In this fourth set of experiments, the researchers wanted to identify the role of β-catenin at different amputation locations for the experiment animals while different genes were silenced and then comparing this to control animals with no genes silence but the same amputations. Amputations included removing the head or tail to see if the head or tail itself would regenerate. In addition, some animals were divided in half longitudinally (lenthwise) and some were divided in half mediolaterally (divided into anterior and posterior halves).

    4. We therefore observed unamputated (intact) worms 14 days after the final RNAi feeding.

      In the fourth series of experiments using the various amputation location, it was noted that in some of the experimental animals that several photoreceptors and brains developed in the wrong location on the same animal. To understand why this happened, unamputated worms had the same genes silenced as the experimental animals and were observed for two weeks.

    5. Smed-sFRP-1, a homolog of secreted Frizzled-related proteins (sFRP), was expressed in an arch of cells capping the anterior edge of the animal. In contrast, Smed-fz-4, a homolog of Frizzled receptors, was expressed at the posterior edge in a posterior-to-anterior gradient. We refer to Smed-sFRP-1 and Smed-fz-4 as the “anterior marker” and the “posterior marker,” respectively, in all subsequent analyses.

      The use of the anterior and poster markers will allow the researchers to determine if posterior cells are indeed moving to the posterior end and if anterior cells are moving to the anterior end in the RNAi treated animals.

    6. we used two markers identified during our in situ analyses that are specifically expressed at the anterior and posterior ends of intact and regenerating animals (Fig. 1, A, O, and S)

      Genes that are expressed only at the anterior or posterior ends were tagged to identify their location in both control and experimental animals while they are regenerating. This allows the researchers to identify the extent to which the stem cells were affected when silencing the proteins. Researchers can compare the control animal's cell migration to the the cell migration in the experimental animals for each of the silenced genes and gene combinations.

    7. To address whether these changes were superficial or reflected a fate transformation of internal cell types and organ systems, we used anatomical and molecular markers of A/P identity.

      In order to determine whether the changes in anterior/posterior identity were temporary changes that influenced the cells to act like a different cell type or whether DNA expression itself was permanently change, Alvarado and colleagues examined the location of the anatomical structures that regenerated. In addition, they identified the active molecular markers, which are chemicals that will help identify the activity of cells in a specific area to determine what type of cell they are. In this research, the markers direct the cells where to go (anterior or posterior). Some are active only for certain time periods of the regeneration process.

    1. Cranial size and lower first molar area were used to estimate mammalian body mass – an important feature that impacts many aspects of the biology and ecology of mammals

      An important step in the authors' research was the determination of the body masses of the fossil mammals they unearthed. Body mass was estimated by measuring the length × width (L×W) of the first lower molar. This has been found to be an accurate indicator of body mass through comparisons to molar size and the body mass of living mammals. This data is important to the authors since body mass has been linked with characteristics such as energy expenditure, gestational period, temperature regulation, and niche ecology. When reconstructing life during the time period being studied, body mass distributions in mammalian communities can be used to infer ancient environmental conditions. Therefore, determining the body mass of a fossil mammal is an important step toward understanding its paleoecological role. Brain size (cranial size) usually increases with the size of the animal. However, the relationship is fairly inaccurate, as cranial size does not correlate as closely to body mass as the area of the first molar does.

    2. In addition, the pattern and abundance of vertebrates preserved in all paleoenvironments suggest that by ~700 ka post KPgE the largest mammals (25+ kg) were spatially partitioned across the landscape.

      The fossil record shows that after the K-Pg extinction event, there was an exponential increase in the maximum size of mammals. About 40 million years ago, this size increase leveled off. It is hypothesized that diversification to fill ecological niches was the primary driver of this rapid increase and that environmental temperature and land area have acted to constrain the continued increase.

    3. Taeniolabis taoensis [(K) and (L)

      This mammal was a specialist and was proof that mammals were evolving and becoming larger as they specialized. Increased plant diversity fueled this growth.

    4. concretions and are found in all observed facies

      These are compact masses of mineral matter, usually spherical or disk-shaped. They are carried along by water and become embedded in host rock that has a different composition. Concretions form in sediments before the sediments become rocks. The authors focused on searching for and cracking open concretions.

    5. The K–Pg boundary is demarcated by the decrease in abundance of Cretaceous pollen taxa

      Fossil pollen reveals how plant species evolved after the K-Pg extinction. The authors compared pollen from both sides of the K-Pg boundary. The authors discovered that immediately after the impact, there were few plants.

    6. two U-Pb radiometric dates

      To determine the age of some of the rocks in their study area, the authors used uranium-lead dating. It is most often used to date volcanic and metamorphic rock and very old rocks. This technique involves the radioactive decay of U-238 and U-235 into lead (Pb). The 238 and 235 refer to the sum of the number of protons (92) and neutrons in the nucleus of each of these forms of radioactive uranium. The half-life, which is how long it takes half of a sample of the U-238 to undergo radioactive decomposition and become Pb-206, is 4.47 billion years. The time it takes for half of a sample of U-235 to decay into Pb-207 is 704 million years. Since the two different forms of uranium have different half-lives and decompose into different forms of lead, they are a good check when calculating the age of a rock or fossil. This dating technique is best used on rocks that are from 1 million to 4.5 billion years old.

    7. CA-ID-TIMS U-Pb-dated volcanic ash

      This technique was used by the authors to date rock strata. Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) is a multistep, high-precision technique used to determine the relative amounts of uranium-238 and lead-206 present in zircon crystals. Zircon crystals, formed from volcanic or metamorphic rock, are extremely durable and resistant to chemical breakdown. They can survive major geologic events. Over time, new zircon layers form on top of the original crystal. The center of the zircon remains unchanged, keeping the chemical characteristics of the rock in which it originally formed. Every radioactive element has a decay rate. The length of time it takes half of the radioactive atoms in a sample to decay (form into a different element) is referred to as its half-life. The half-life of uranium-238 to lead-206 is 4.47 billion years. The authors selected zircon crystals from their study area and dated them using CA-ID-TIMS.

      Image of thermal-ionization mass spectrometer: https://www.usgs.gov/media/images/usgs-thermofinnigan-triton-thermal-ionization-mass-spectrometer

    8. paleomagnetics

      This is the study of the magnetism in rocks induced by Earth's magnetic field. The minerals in certain rocks lock in the direction and strength of the magnetic field at the time of their formation. The authors used this method to determine the age of their fossil finds.

    9. high-resolution stratigraphic framework

      To analyze what happened in these basin areas, the authors used sequence stratigraphy. They looked for variations in the successive layers of sedimentary rocks and the composition of the rocks. The order in which the different layers were deposited was carefully recorded. The chronostratigraphy aspect of their fieldwork involved tracking changes in the character of the rocks through geologic time. Fossils found in each layer can then be better placed in terms of when these organisms evolved, and in some cases, became extinct.

      Learn more about stratigraphy from HHMI BioInteractive: https://www.biointeractive.org/classroom-resources/stratigraphic-principles

  13. Apr 2020
    1. low quantitative variation

      The authors used descriptive statistics, calculating the mean and the standard error of the mean to quantify the variation in the populations. n=42 means that 42 measurements were included in the calculations.

    2. We followed the survival and breeding of this individual and its descendants for six generations over the next 31 years.

      The Grants began studying finches on Daphne Major Island in 1972. Along with team members, they returned there every year until 2012 to observe the finches. Observations included identities of mating pairs, number of offspring (used to construct pedigrees) and mortality of birds (recording deaths of birds).

      The techniques used included catching the birds and banding them (installing identification bands around their legs), as well as taking measurements of the birds (including body mass and beak measurements). Blood samples were also collected for later DNA analysis.

    3. ADMIXTURE (19) analysis

      ADMIXTURE is a program that can quantify inbreeding by estimating allele frequencies and ancestry proportions. It helps scientists to understand how much of a genome is derived from inbreeding with other populations in the past.

      This analysis and the inbreeding coefficient analysis helped to confirm the founder's species as G. conirostris.

    4. inbreeding coefficient (F)

      A statistical calculation that estimates the probability that an individual inherited two identical genes from one ancestor that occurs on both sides of the pedigree. The higher it is, the more inbred the organism is.

      It was used to both help assign the founder bird to a species and to quantify the genetic diversity of the Big Bird population as it bred amongst itself.

    5. confirmed pedigree assignments

      A computer program was used to create many possible pedigrees based on the genetic data and to analyze the likelihood of each relationship in the pedigree using the genomic data. The most likely pedigree inferred from the data was mostly in agreement with the pedigree based on observations, with only a few changes.

    1. we developed an approach that uses rapid pH change to drive collagen self-assembly within a buffered support material, enabling us to (i) use chemically unmodified collagen as a bio-ink, (ii) enhance mechanical properties by using high collagen concentrations of 12 to 24 mg/ml, and (iii) create complex structural and functional tissue architectures.

      The authors prefer to 3D print collagen in its natural form, but this comes with a challenge. Unmodified collagen transforms into a gel by forming links between individual structures, and this process is difficult to control at physiological pH values of 7.4.

      To resolve this issue, the authors prepared collagen bioinks by dissolving collagen in an acidic solution. By dispensing this bioink in a buffered support gel, the pH of the collagen ink is quickly neutralized to 7.4 which promotes the linking process.

      This allowed the authors to 3D print unmodified collagen, with higher density and strength, in complex shapes and structures.

    2. Filament morphology from solid-like to highly porous was controlled by tuning the collagen gelation rate using salt concentration and buffering capacity of the gelatin support bath

      The authors were able to control the porosity of the 3D printed filaments by controlling the salt concentration and pH of the support bath.

    3. Finally, to demonstrate organ-scale FRESH v2.0 printing capabilities and the potential to engineer larger scaffolds, we printed a neonatal-scale human heart from collagen

      Previous experiments have only demonstrated small-scale applications such as printing a ventricle and a valve. So, in their last experiment, the authors printed an infant-sized heart to show the larger-scale printing capability of FRESH v2.0 towards printing a fully functional artificial organ.

    4. A magnetic resonance imaging (MRI)–derived computer-aided design (CAD) model of an adult human heart was created, complete with internal structures such as valves, trabeculae, large veins, and arteries, but lacking smaller-scale vessels.

      MRI uses magnetic field and radio-frequency waves to create detailed 3-dimensional pictures of organs within the body. The authors developed a 3D model of the adult human heart was developed by using magnetic resonance imaging (MRI) images.

      Due to low resolution of MRI imaging, their 3D heart model included valves and large vessels, but was missing the smaller-scale vessels. The authors later added the small vessels to their model by using a special computer program. The authors then used this 3D model to FRESH-print human heart.

    5. We imaged the ventricles top-down to quantify motion of the inner and outer walls (Fig. 3K).

      The authors observed the printed ventricle as it contracted to see how the walls thickened during the contractions. This was done because wall thickening is a typical behavior of ventricle contraction.

    6. Filament morphology from solid-like to highly porous was controlled by tuning the collagen gelation rate using salt concentration and buffering capacity of the gelatin support bath

      The authors were able to control the porosity of the 3D printed filaments by controlling the salt concentration and pH of the support bath.

    1. Preservation of He and its isotope signatures in diamond is supported by He heterogeneities within individual diamonds

      In conducting their experiments, the research team acknowledged the inherent variability in the <sup>3</sup>He/<sup>4</sup>He ratio inside each diamond. To minimize these differences, the scientists used diamonds that were free of inclusions thereby eliminating the possibility of inconsistencies in helium ratios originating from these inclusions. Then, they crushed the diamond in a vacuum to verify that 90% of the helium is present in the groundmass of the diamond. This was then followed by step-heating the crushed diamond to measure the variability in the <sup>3</sup>He/<sup>4</sup>He ratio in the diamond.

    2. We removed the outer rim of the diamond to eliminate any 4He implantation [up to 30 μm from the diamond surface

      The outer rim may be contaminated by helium-4 (4He) from the surrounding material. Removing the outer rim consisting of helium-4 isotopes from the diamonds narrows the search to helium-3 isotopes located in very ancient chemical reservoirs. This removal is an experimental design to attempt to get a pure analysis of the helium only from the diamond.

    3. Resolving the existence and location of a long-term preserved, primordial, undegassed, high-3He/4He reservoir, and where it interacts with other reservoirs in the mantle, is key to understanding the evolution of Earth and deep mantle convection.

      The research team sought to identify an untouched, untapped chemical reservoir. To do this, they decided to examine primordial diamonds that contained both helium-4 and helium-3 isotopes.

      The helium-4 isotopes are formed from radioactive decay of trace elements and hence take a long time to form. Conversely, the helium-3 isotopes exist inside Earth from the early days of formation and there has been no new generation of helium-3 isotope since then.

    4. We studied 24 diamonds (1.3 to 6 mm in size) from the Juina-5 and Collier-4 kimberlites and São Luiz River (Juina, Brazil).

      The authors carefully inspected 24 diamonds excavated from the Juina area of Brazil. This location was chosen because the diamonds excavated from this area show characteristics similar to the ones that belong to the Earth's transition zone (410 to 660 km depth). Kimberlite pipes are an explosive and geologically "quick" process that brings diamonds up to the Earth's surface with little to no interaction with the surrounding rocks, making them ideal for this study. The sizes of these diamonds ranged between 1.3 mm to 6 mm. Despite the size limitation, the research team could successfully detect the helium gases trapped in these diamonds.

    1. A series of x-rays for the three animals treated with long-acting formulation–2 are shown in Fig. 2D.

      Fig. 2D shows X-ray images of the smart pill containing long-acting formulation–2 over 29 days. Two arms of the pill broke off in pig 3, but the pill was still able to remain in the stomach and provide consistent drug concentrations.

    2. a drug-polymer matrix within the sleeve

      For extended release, the birth control pill (levonorgestrel (LNG)) can be loaded within the structural polymer that makes up the arms.

    3. Despite this, the arms retained sufficient rigidity appropriate for incorporation in the dosage forms.

      Even with a decrease in flexural strength, the arms of the smart pill still have sufficient rigidity to move forward with the experiment. If the rigidity was affected more drastically, it could lead to the arms breaking inside the stomach. The arms are meant to keep the smart pill large enough so that it is too big to pass through the pylorus, therefore arm breakage could lead to early digestion of the pill.

    4. folding into a capsule to facilitate oral administration

      The smart pill is able to fold into itself to fit inside a capsule for ingestion.

    1. We fabricated single- and two-unit planar HASEL actuators, where a unit is defined as a discrete region of liquid dielectric (figs. S8 and S9) (24). Linear actuators were oriented vertically with the load applied in the direction of gravity, but they can be operated in any orientation as long as the liquid dielectric regions are sufficiently small to limit uneven distribution of liquid dielectric (fig. S10). A single-unit planar HASEL actuator (Fig. 3C) was activated by increasing DC voltage in discrete steps and achieved a maximum of 79% linear actuation strain under a load of 250 g (actuation stress ~32 kPa), exceeding typical values of strain observed for biological muscle (26).

      Single and two-unit planar HASEL actuators are built as explained in Figures S8 and S9. Linear actuators are vertical, with the load applied downward in the same direction of gravity. DC voltage is increased in small quantities, activating the planar actuator. The maximum strain detected is a 79% strain under a 250 g load.

    2. To compare the actuation response of HASEL and DE actuators, we measured area strain as a function of voltage for two circular actuators with the same total dielectric thickness, t (Fig. 3A). Both were fabricated from Ecoflex 00-30 (Smooth-on); however, one-third of the thickness of the HASEL actuator was liquid dielectric, tliq (24). At 11 kV, the area strain of the HASEL actuator exceeded the area strain of the DE actuator by a factor of ~4 (Fig. 3A and fig. S7).

      To test the effectiveness of their design, the authors fabricated a dielectric (DE) actuator and a HASEL actuator with same dimensions. They tested the amount of in-plane expansion as a function of voltage. HASEL actuators expanded more (46% compared to 12%) under same conditions.

    3. We modified two stacks of donut HASEL actuators to operate as a soft gripper, a common application for soft robotics (8, 28). Actuators within the stacks were constrained on one side to produce a tilting motion (Fig. 2, C to G, and fig. S6).

      Two stacks of HASEL actuators are tilted and fixed to form a gripper for other items, as seen in Figure 2 C-G. When a voltage is applied, the grippers are able of grabbing fragile objects including an egg and a raspberry.

    4. The use of liquid dielectrics enables HASEL actuators to self-heal from dielectric breakdown. In contrast to solid dielectrics, which are permanently damaged from breakdown, liquid dielectrics immediately return to an insulating state (fig. S5 and movie S1). This characteristic allowed donut HASEL actuators to self-heal from 50 dielectric breakdown events

      HASEL uses a liquid dielectric instead of a solid dielectric. Dielectric breakdown can be considered like a lightening strike. The sky and the ground are the opposite sides of the dielectric. When the power is too high there is a breakdown and the opposite sides connect and conduct electricity, a lightening strike.

      The connection is extremely powerful, just like a lightening bolt, and will often burn holes through the dielectric. HASEL actuators, using a liquid dielectric, are protected from these breakdowns. When a hole is burnt through the liquid dielectric, it is filled in with the surrounding liquid, effectively healing it.

    5. The actuator with larger electrodes displaced more liquid dielectric, generating a larger strain but a smaller force, because the resulting hydraulic pressure acts over a smaller area (Fig. 1D and fig. S2). Conversely, the actuator with smaller electrodes displaced less liquid dielectric, generating less strain but more force, because the resulting hydraulic pressure acts across a larger area (Fig. 1E).

      The relative size of the electrode determines the mount of force it can generate.

      Smaller electrodes can squish less liquid dielectric material between the electrodes. However, they generate a larger force by causing a smaller strain (rise) over a larger area in the donut.

      Larger electrodes can squish more liquid dielectric material between the electrodes. However, they generate a smaller force by causing a larger strain (rise) over a smaller area in the donut.

    6. Because Maxwell pressure is independent of the electrode area, actuation force and strain can be scaled by adjusting the ratio of electrode area to total area of the elastomeric shell.

      You can control the force generated by the actuator by changing the area of the electrode with respect to the overall area of the actuator.

      Think of what the water balloon looks like when you push it down with one finger compared to two. The more fingers you used, the larger the area of the balloon you touch, and the higher the sides of the balloon would rise.

    7. After the pull-in transition (Fig. 1A), actuation strain further increases with voltage (Fig. 1B). For this design, hydraulic pressure causes the soft structure to deform into a toroidal or donut shape (Fig. 1C).

      Once the snap-in voltage is passed, the electrodes move further towards each other with increased voltage. The more voltage applied to the electrodes, the more HASEL actuator is squished.

      HASEL actuator is initially shaped like a disk, but when voltage (exceeding the snap-in voltage) is applied, it deforms into a donut shape.

    8. As voltage increases from V1 to V2, there is a small increase in actuation strain s. When voltage surpasses a threshold V2, the increase in electrostatic force starts to exceed the increase in mechanical restoring force, causing the electrodes to abruptly pull together (Fig. 1B)

      As you increase the voltage to the HASEL electrodes the dielectric become more polarized. The electrostatic attraction is fighting against the pressure of the liquid dielectric in HASEL. The electrostatic attraction is equivalent to your finger pushing down on the water balloon and the liquid dielectric pressure is equivalent to the balloon resisting your push.

      As voltage is increased, the electrostatic (attractive) force becomes greater than the liquid pressure and the electrodes begin to move towards another. Similar to: when you finally push hard enough, the balloon begins to squish.

      The voltage high enough to cause this change is called the "snap-in voltage".

    9. electrostatic Maxwell stress (20) pressurizes and displaces the liquid dielectric from between the electrodes to the surrounding volume.

      When the dielectric is polarized it, it generates a force which pulls the two electrodes together. Electrostatic Maxwell Stress is a mathematical model that explains the strain caused by these two electrodes being electrostatically attracted to each other. This electrostatic force is like pushing the water balloon in the middle.

    10. HASEL actuators, where an elastomeric shell is partially covered by a pair of opposing electrodes and filled with a liquid dielectric (Fig. 1A).

      Researchers chose HASEL's structure because they wanted stable uniform force to be distributed from the actuator.

      When you push in the middle of the water balloon you raise all the sides around your finger equally. If you push off-center, or squish balloon on the side, you have a less equal distribution of pressure. Therefore, the researchers placed the electrodes in the middle of the actuator (on top and bottom surfaces).

    11. HASEL actuators generate hydraulic pressure locally via electrostatic forces acting on liquid dielectrics distributed throughout a soft structure.

      A HASEL actuator is like a half-filled water balloon. If you press in the middle of the balloon with your finger, you force the water from the middle of the balloon to the outer edges.

      HASEL actuator is filled with a liquid dielectric that does not conduct electricity. Electrical power is supplied to the electrodes placed in the middle of the top and bottom surfaces of a HASEL actuator.

      The electrical power polarizes the dielectric, and generates electrostatic force in the middle of the actuator, similar to pressing your finger in the middle of the water balloon. This force help inflate the sides of the actuator, generating a hydraulic force in the vertical direction.

    12. Here, we develop a class of high-performance, versatile, muscle-mimetic soft transducers, termed HASEL (hydraulically amplified self-healing electrostatic) actuators.

      The researchers named their actuator "HASEL". They explain that HASEL is a higher-performance, versatile, muscle mimetic soft transducer, combining the advantages of fluidic and electrostatic actuators.

      Higher-performance: compared to other soft-robot actuators HASEL uses less energy to generate larger movement.

      Versatile: HASEL can lift weights or used to grab delicate objects (soft gripper).

      Muscle Mimetic: HASEL mimics the movement of human muscles based on extension and contraction of muscle fibers.

      Soft transducer: HASEL transfers electric energy into mechanical energy.

    13. To demonstrate self-sensing actuation, we powered a robotic arm with two planar HASEL actuators combined in parallel and simultaneously measured capacitance (Fig. 4, fig. S16, and movies S7 and S8).

      HASEL actuators are able to sense strain through capacitance, which is a direct relationship: when strain is low, capacitance is low; when strain is high, capacitance is high. In this experiment, two planar HASEL actuators are combined in parallel to simultaneously measure capacitance during various movements of a robotic arm. Capacitance is low when the arm is flexed, while capacitance is high when the arm is extended.

    14. analyzing the phase and amplitude of voltage and current signals (fig. S15)

      The actuation voltage signal and sensing voltage signal were combined in LabVIEW and output from a data acquisition system to a high voltage amplifier. The amplified voltage signal was then applied to the HASEL actuator. Current and voltage were monitored from the high voltage amplifier and input to the data acquisition system, allowing self-sensing of HASEL actuators.

    15. Nonetheless, the ability of planar HASEL actuators to tolerate high electric fields applied over large areas enabled us to scale up actuation force by combining six planar HASEL actuators in parallel to lift a gallon of water (~4 kg, which corresponds to ~120 kPa) at 69% linear actuation strain (Fig. 3D and movie S6).

      The force of actuation can be significantly increased by combining multiple planar HASEL actuators. In this experiment, authors combined six planar actuators in parallel to test the work and strain. A gallon of water weighing 8.82 lbs was lifted, and a linear actuation strain of 69% was achieved.

    16. Planar HASEL actuators were also able to self-heal from dielectric breakdown for at least 50 cycles

      In this experiment, the authors tested the ability of planar HASEL actuators to self-heal using a six-unit actuator. Voltage was steadily applied at 0.5 kV/s until dielectric breakdown occurred. After a minute, voltage was reapplied until dielectric breakdown occurred again. This cycle was repeated 50 times to evaluate the self-healing performance of the actuator.

    17. until mechanical rupture occurred at 158,061 cycles (fig. S12D)

      To determine the cycle life of the actuator, contractions were repeated until failure. 158,060 mechanical contractions were successfully completed before the actuator ripped, showing that the actuator is able to operate efficiently under large loads for an extended period of time.

    18. The ability of HASEL actuators to self-heal from electrical damage provides the means to scale up devices to produce a large actuation stroke by stacking multiple actuators (Fig. 2A)

      Stacking actuators allows for generating larger movement in comparison to one actuator. Since these actuators self heal from electrical damage, the actuation stroke can be increased without permanent damage to the system.

  14. Mar 2020
    1. The serum concentration of levonorgestrel in pigs treated with Levora tablets is shown in Fig. 2A.

      Fig. 2A shows the concentration of the drug from a Levora tablet in a pig over the course of 2 days. The concentration reaches it's peak of 199 ± 56 pg/ml (n = 5) at around 6 hours and by 48 hours dropped to 5 ± 4 pg/ml (n = 5).

    2. We then tested the stability of the interface between the material used to make the central elastomer (Elastollan 1185A10) and the arms of the dosage form (Sorona 3015G NC010) using a cyclic cantilever test. Over a 3-week period, there was progressive weakening of the interface (Fig. 1D).

      This method helps determine the load that can be repeatedly applied to the joint area between the central elastomer and the arms while still keeping its structural integrity.

    3. arms that had V-shaped grooves in them

      This arm design was initially used because of the higher surface area it allowed in comparison to the other designs.

    4. 45 ± 2 pg/ml (n = 3) and 54 ± 29 pg/ml (n = 3) on days 3 and 11, respectively.

      Using the capsule with three arms, they found concentrations of 45 ± 2 pg/ml on day 3 and 54 ± 29 pg/ml on day 11. These results illustrate that the capsule is steadily releasing the hormone over a 20-day period. One problem with this formulation is that the drug concentration fluctuates significantly over time which may reduce its effectiveness for pregnancy protection.

    5. Using long-acting formulation–1, we observed a maximal concentration of 55 ± 18 pg/ml (n = 3) on day 17 (Fig. 2B).

      Using the capsule with half of the drug loaded in poly(sebacic anhydride) and the other half in PDMS, the authors illustrated birth control drug delivery for an extended period. They observed a peak concentration of the drug on day 17. This shows that, unlike the daily tablet, their formulation slowly and steadily releases the drug and provides protection over a longer period.

    6. The flexural strength of the arms was reduced after 2 weeks of incubation in SGF

      After a period of 2 weeks in the simulated stomach acid, the strength of the caged arms decreased. The integrity of the polymeric arms are affected by exposure to the acid. The decrease in strength is ~25% after 2 weeks.

    7. assumes a size larger than that of the pylorus;

      After ingestion, the smart pill is released from the capsule and expands to a size larger than the stomach's opening, which prevents it from passing into small intestine. This will allow for the extended release of the birth control drug within the stomach.

    1. we printed a tri-leaflet heart valve 28 mm in diameter

      A heart valve was printed with the collagen gel and was strengthened using standardized methods.

      Heart valves are structures with flaps of tissue (leaflets) that open and close. This allows blood to flow out to the rest of the body, and prevents it from flowing back into the heart (regurgitation). The valve printed here was 28 mm which is within human range, and was tri-leaflet meaning it contained 3 flaps.

      This is an important experiment because heart valves experience extreme forces in the body. If the overall goal for the authors is to 3D print full organs, they need to verify that their collagen can withstand these forces.

    2. We next FRESH-printed a model of the left ventricle of the heart using human stem cell–derived cardiomyocytes.

      The authors 3D printed a left ventricle, the bottom left chamber of the heart that pumps blood out to the body. They printed collagen gel for structure, and also used a cellular ink containing human embryonic stem cell-derived cardiomyocytes (hESC-CMs) which are the contracting cells in the heart.

      The ventricle was designed as an ellipsoidal shell with an outer and inner wall printed from collagen gel. The hESC-CMs were printed in the space between the two walls along with 2% cardiac fibroblasts, cells that produce connective tissue.