39 Matching Annotations
  1. Apr 2020
    1. In the first of two enzymatic steps that produce high-glucose syrup as an intermediate to high-fructose syrup and other products, bacterial α-amylase is employed at pH 6–7 and about 105°C to hydrolyze starch purified by wet milling to roughly DE (dextrose equivalent) 10, DE being the percent of reducing end-groups in the aqueous sugar mixture relative to those in pure glucose of the same concentration. This indicates that the average maltooligosaccharide produced has a DP (degree of polymerization) of 10, although the mixture has a very wide DP range. DE 30 or more can be attained if the reaction proceeds to completion, but DE 10 is chosen to minimize the probability of pseudo-crystallization at lower DEs and the extent of alkaline-catalyzed isomerization of the reducing-end glucosyl residue at higher DEs.In the second step, at pH 4.3–4.5 and roughly 60°C, fungal glucoamylase and a small amount of pullulanase (pullulan 6-glucanohydrolase, EC, the latter used to rapidly hydrolyze the α-1,6 bonds from the original starch feed, convert the maltooligosaccharide mixture to approximately 96% glucose (dry basis). The remainder is composed of byproducts from α-amylase hydrolysis plus mainly isomaltose [α-glucopyranosyl-(1,6)-glucose] and isomaltotriose from the glucoamylase-catalyzed condensation of glucose.

      If I'm understanding this correctly, all I need is alpha amylase (easily obtainable) and beta amylase (AKA glucoamylase, also obtainable). When buying these, I've found that alpha amylase is advertised as simply amylase, whereas beta amylaze is advertised as glucoamylase

      This mentions both pH and temperature, but fails to mention time. I'd expect it only takes a matter of hours (or less).

  2. Dec 2019
    1. It was, perhaps, the amiable character of this man that inclined me more to that branch of natural philosophy which he professed,

      The relationships between Victor and his teachers appear to drive the interdisciplinary curiosity that leads to his later discoveries. For example, M. Waldman, who loves chemistry, notes that "I have not neglected the other branches of science," and neither does Victor.

    2. this day natural philosophy, and particularly chemistry, in the most comprehensive sense of the term, became nearly my sole occupation

      The special role of chemistry in Victor's apprenticeship to medicine links premodern sciences like alchemy to modern empirical science. Humphry Davy (1778-1829)was the contemporary British chemist who argued the chemistry was the key to all other sciences and useful arts of the time.

  3. Nov 2019
    1. To grow, trees photosynthesize and turn water and carbon dioxide (pulled from the air), into hydrocarbons. A living tree sucks carbon dioxide from the air and locks it into wood as it grows. Even when the tree dies (unless we burn it), the carbon is still locked up in the wood

      Cycle of tree's life

    2. For a wood fire, ash is primarily composed of metal carbonates and oxides (such as Calcium Carbonate, and Potassium Carbonate), from the compounds in the original wood

      Ash - compounds that did not burn

    3. As long as there is a source of fuel (and oxygen), the fire will burn

      Oxygen keeps the fire alive

    4. As the fire gets hotter, more complete combustion occurs, less smoke is produced, and the flames lose the yellow color, turning more blue

      As the fire gets hotter:

      • more complete combustion
      • less smoke
      • yellow colour turns into blue
    5. yellow flames seen in a fire are the result of incomplete combustion

      Yellow flames - incomplete combustion

    6. smoke produced (early stages of fire) is unburned carbon

      Smoke - unburned carbon

    7. It is the volatile compounds that out-gas from the wood, and eagerly react with oxygen, that are burning, and generate the flames we see

      Generation of flames - volatile compounds eagerly reacting with oxygen

    8. When the temperature of wood is increased (through application of heat), first the water is driven off. This occurs up to about 200°C. Between approximately 200°C–280°C the heat starts to break down the hemicellulose compounds into Carbon Monoxide, Carbon Dioxide, Acetic Acid, (and more water vapour); these are driven out. Between 280°–500° decomposition of the longer cellulose and lignin begins and produces light tars and Methyl Alcohol

      Burning process:

      1. < 200°C - water is driven off
      2. 200°C-280°C - heat breaks down the hemicellulose compounds into Carbon Monoxide, Carbon Dioxide, Acetic Acid, and more water vapour
      3. > 280°C - hydrogen is still produced. Oxygen reacts directly with the Carbon left in the wood exothermically (process happening in the glowing embers)
    9. A couple of hundred intermediate products (organic acids, ketones, esters, aldehydes …) have been identified as being produced by the pyrolysis of wood

      Output from wood pyrolysis

    10. The pyrolysis of wood is an incredibly intricate and complex process that is not completely mapped out and the exact output depends of many variables

      Pyrolysis is complex and relies on lots of variables (type of wood, temperature...)

    11. The correct term to describe what is going on when we ‘burn’ wood is Pyrolysis

      Pyrolysis (from Greek) - correct term for "burning" wood (thermal decomposition)

    12. The chemical composition of wood varies from species to species, but is approximately 50% carbon, 42% Oxygen, 6% Hydrogen, 1% Nitrogen, and 1% other elements (mainly Calcium, Potassium, Sodium, Magnesium, Iron, and Manganese) by weight

      Chemical composition of wood. Mainly:

      • 50% carbon
      • 42% oxygen
      • 6% hydrogen
  4. Sep 2019
    1. It should be noted here that the substitution of LiTFSI forLiClO4could be expected to affect the reactions of polysuldesat the negative electrode surface; LiClO4, like LiNO3,isa powerful oxidising agent which may contribute to thepassivation of the negative electrode

      Testing with document hosted on MP.

  5. May 2019
    1. The metal is a solid material and metallic gray in color. Furthermore, the metal possess high melting and boiling points. At standard temperature and pressure, cobalt is not readily oxidized, which means it does not easily lose electrons from its surface.

      A description of cobalt.

    2. cobalt can be found among the d-block elements, transition metals. It has the chemical abbreviation Co and atomic number 27.

      Where to find cobalt on periodic table and cobalt's atomic number.

  6. Mar 2019
    1. A nano-porous carbon composite membrane has been found to display high water flux due to exceptionally high surface diffusion, together with an excellent salt rejection [2616, 2958].

      With an excellent ability to reject salt, how often does membrane fouling become an issue when desalinating seawater? to a point where it causes water flux decline and lowers the quality of the water produced.

      ~ Anthony Y.

    1. common oxidizing agents: Halogens (they favor gaining an electron to obtain noble gas configuration).

      • O2, O3, F2, Br2, H2SO4

      common reducing agents: Alkali metals (they favor losing an electron to obtain noble gas configuration).

      • H2, CO, Fe, Zn, Li
  7. Oct 2018
    1. are step-by-step descriptions of what occurs on a molecular level in chemical reactions. Each step of the reaction mechanism is known as an elementary process, a term used to describe a moment in the reaction when one or more molecules changes geometry or is perturbed by the addition or omission of another interacting molecule. Collectively, an overall reaction and a reaction mechanism consist of multiple elementary processes. These elementary steps are the basic building blocks of a complex reaction, and cannot be broken down any further.

      reaction mechanisms

  8. Jun 2018
  9. May 2018
  10. Mar 2018
    1. alembics
      1. Chem. An early apparatus used for distilling, consisting of two connected vessels, a typically gourd-shaped cucurbit (cucurbit n.1 1) containing the substance to be distilled, and a receiver or flask in which the condensed product is collected. Occasionally also: spec. the lid or head (head n.1 19f) of the cucurbit together with its tube or beak which connects the two vessels. Now hist. (from Oxford English Dictionary)
  11. Nov 2016
    1. Two new molecular catalysts of water oxidation have been synthesized by a team of brilliant scientists from the U.S. Department of Energy’s Brookhaven National Laboratory. These new molecular catalysts – complexes of ruthenium which are surrounded by the binding molecules, and they contain phosphonate groups.

  12. Jun 2016
    1. Title: The dying breed of craftsmen behind the tools that make scientific research possible - LA Times

      Keywords: government-funded research opened, snake glass coils, fuse glass beakers, organic chemistry, research hubs, world war, experienced glassblowers, glassblowers remain, church laboratory, befallen glassblowing, glass manufacturer, glass technicians, cost-cutting world, jobs tend, entry-level jobs

      Summary: Hunkered down in the sub-basement of the Norman W. Church Laboratory for Chemical Biology, underneath a campus humming with quantum teleportation devices, gravity wave detectors and neural prosthetics, Rick Gerhart chipped away at a broken flask.<br>Peering into the dancing flames, he examined his work for wrinkles — imperfections invisible to the untrained eye.<br>“It not only should be functional,” he said, smoothing the rim with a carbon rod, “it has to look good.”<br>Here in Caltech’s one-man glass shop, where Gerhart transforms a researcher’s doodles into intricate laboratory equipment, craftsmanship is king.<br>In a cost-cutting world of machines and assembly plants, few glassblowers remain with the level of mastery needed at research hubs like Caltech.<br>“He’s a somewhat dying breed,” said Sarah Reisman, who relied on Gerhart to create 20 maze-like contraptions for her synthetic organic chemistry lab.<br>Rick Gerhart, scientific glass blower at Caltech, has been helping to make scientific research possible at the campus since 1992.<br>(Dillon Deaton/Los Angeles Times)<br>Similar fates have befallen glassblowing at UCLA and NASA’s Jet Propulsion Laboratory.<br>Across the U.S., those who land such jobs tend to stay until retirement.<br>He chuckled: “Looks like we have to steal somebody.”<br>To master scientific glassblowing, proper training and apprenticeships are key.<br>In addition to the hands-on training, which requires a knack for precision as well as coordination, students must take courses in organic chemistry, math and computer drawing.<br>So it really takes a long time to get to a position like Rick’s.”<br>Gerhart enrolled in the Salem program in 1965, after dropping out of college to give his father’s profession a try.<br>The craft, which dates back to alchemy in the 2nd century, took hold in America by the 1930s and 1940s, after World War I cut off glassware supply from Germany.<br>The profession peaked after World War II, when booms in oil and government-funded research opened up numerous glassblowing jobs in many a lab.<br>At first, Gerhart hopped around a number of firms and worked alongside more experienced glassblowers at TRW Inc. and UCLA.<br>When he settled at Caltech in 1992, the glassblower before him handed over the key to the shop and said, “Good luck.” On his own, Gerhart pieced together his patchwork of experience to twist and fuse glass beakers and snake glass coils over vacuum chambers.<br>“That’s when I really started learning.”<br>Social media videos have sparked new interest in the craft, Briening said.<br>But while his students have no trouble getting entry-level jobs at companies like Chemglass Life Sciences, a glass manufacturer, and General Electric Global Research, rarely are universities willing to budget the overhead costs for more than one glassblower, if any.<br>“Years ago, all the universities had two or three people,” Briening said.<br>One of the few resources left for the next generation is the American Scientific Glassblowers Society, a close-knit group that hosts national workshops and swaps ideas when a researcher’s custom order stumps one of its members.<br>Its members also serve as Caltech’s best — and possibly only — options once Gerhart leaves.<br>“Rick’s one of those glass technicians that I put in the top 5%,” Ponton said.<br>

    1. The four new synthetic elements have been named.<br> 113 nihonium (Nh)<br> 115 moscovium (Mc)<br> 117 tennessine (Ts)<br> 118 oganesson (Og)

  13. May 2016
    1. After hundreds of emails with developers and peer-reviewers, his open-source book will be ready for use at UConn. Neth began planning for the second version of the book in January and the project has taken more than four months.
  14. Jan 2016
    1. Elements 113, 115, 117, and 118 were recently produced in laboratories. 114 and 116 were created about five years ago. There is a petition to name one of the new elements Lemmium, after rock musician Lemmy Kilmister, who died 28 December 2015. It has 133,465 signatures so far.

      NPR<br> https://twitter.com/LemmiumMetal