Cleaning Diatom Frustules with Ultraviolet Radiation and Peroxide
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Materials Literature
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Studies on the enzymic activity of lysozyme, 3. The binding of saccharides.
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
Measurement of the Glass-Transition Temperature of Simple Liquids
The glass-transition temperatures of 34 liquids have been measured by differential thermal analysis, and the results compared with the values predicted from viscosity measurements by the equation lnη = A″+B″/(T—T0). In those liquids which have two non-Arrhenius viscosity regions, there is good agreement between observ…
Self-diffusion in liquid metals
A survey is made of all published data on self-diffusion in liquid metals and an examination is carried out on the temperature-dependence of D for studies covering a wide range of temperatures. Log D versus 1/T and D versus T represent the best data equally well, while D versus T 1/2 and D versus T 2 do not. The prope…
Pulsed Flashover in Vacuum
Experiments on the vacuum flashover of dielectric frusta subjected to 35 and 75 nsec pulses show the strong influence of cone angle on insulation strength. A theory is presented to explain the formative process leading to flashover for one polarity. It is proposed that positive surface charge grows by emission of hot…
Ferroelectric Rare-Earth Molybdates
The molybdates of Sm, Eu, Tb, and Dy are isotypic with ferroelectric Gd2(MoO4)3. Other compositions of this structure occur in the pseudoternary system Gd–La–Y-molybdate and in the pseudobinary system Gd2(MoO4)3–Gd2(WO4)3. A representative number of these compositions were grown as single crystals and tested for ferro…
Reactivity of lime and related oxides. XVI. Sintering of lime
Abstract Calcium carbonate samples containing known amounts of additives and impurities have been calcined in air at a series of temperatures for different lengths of time. Changes in specific surface and average crystallite size show the effect of the additives and impurities (accessory minerals in limestones and cha…
Tail regeneration in the lizards Anguis fragilis and Lacerta dugesii
Rates of tail regeneration in the Madeira wall lizard (Lacerta dugesii) and the slow-worm (Anguis fragilis) were studied. L. dugesii regenerates very rapidly, the new tail sometimes attaining a maximum rate of growth of 2'6 mm a day during the fifth week after autotomy. By the twelfth week 90% of the original tail len…
High-Temperature Vaporization and Thermodynamics of the Titanium Oxides. I. Vaporization Characteristics of the Crystalline Phases
The vaporization behavior of the titanium—oxygen system has been established by experimental measurements of the change in composition of the solid residue accompanying vaporization as determined by x-ray diffraction, chemical analysis, and color of sample. The solid phases studied were Ti2O, TiO, Ti2O3, Ti3O5, Ti4O7,…
Concentration Quenching of Eu3+ Fluorescence
The fluorescence quenching of the two phosphors Ba2Gd1−xEuxMe5+O6 (Me5+=Nb5+ or Ta5+) and Gd1−xEuxAl3B4O12 is reported. The shortest distance between the rare-earth sites in these materials is large and nearly equal, viz., 6.0 and 5.9 Å, respectively. The quenching behavior is different: In the materials Ba2Gd1−xEuxMe…
OBSERVATIONS OF THERMOPHILIC ALGAL COMMUNITIES IN MOUNT RAINIER AND YELLOWSTONE NATIONAL PARKS
Observations on thermophilic algal communities during a three‐year period at Mount Rainier National Park and during January 1965 and 1966 in Yellowstone National Park have been analyzed to evaluate the distribution of species in thermal streams relative to temperature and competitive interaction. Although temperature…
Phase Equilibria in the System CuMnO
Abstract A T‐x‐section of the phase diagram is proposed for the system CuMnO in air between 750 and 1,400°C. From X‐ray and chemical analyses on quenched samples and from high‐temperature X‐ray diffraction studies the occurrence of the following phases is deduced: a cubic phase α‐Mn 2 O 3 , a phase Cu x Mn 3−x O 4+γ…
Critical surface tension for spreading on a liquid substrate
A plot of the initial spreading pressures (F sub ba) or initial spreading coefficients (S sub ba) against the surface tensions of a homologous series of organic liquids b can be used to determine the critical surface tension for spreading on a second substrate liquid phase a. Straight-line relations are found for vari…
Determination of kinetic parameters for pyrolysis of cellulose and cellulose treated with ammonium phosphate by differential thermal analysis and thermal gravimetric analysis
Abstract Activation energy E , pre‐exponential factor k 0 , and reaction order n for the pyrolysis of α‐cellulose and cellulose modified with dihydrogen ammonium phosphate were determined by means of TGA and DTA. The results obtained are E = 53.5 kcal./mole, k 0 = 10 18.8 min. −1 , n = 1 for α‐cellulose and E = 32 kca…
Glucose-Lactose Diauxie in Escherichia coli
Growth of Escherichia coli in medium containing glucose, at a concentration insufficient to support full growth, and containing lactose, is diauxic. A mutation in the gene, CR, which determines catabolite repression specific to the lac operon, was found to relieve glucose-lactose but not glucose-maltose diauxie. Furth…
Reduced Density Matrices of Atoms and Molecules. I. The 2 Matrix of Double-Occupancy, Configuration-Interaction Wavefunctions for Singlet States
Certain general features of the second-order reduced density matrix, or 2 matrix, for configuration-interaction (CI) wavefunctions are reviewed, with special reference to the simplifying features of spin singlet states. A restricted form of CI in which all spatial orbitals are doubly occupied (DOCI) is proposed for si…
Condensed Phase Relations in the Systems ZrO 2 ‐WO 2 ‐WO 3 and HfO 2 ‐WO 2 ‐WO 3
Phase relations for the systems ZrO 2 –WO 2 –WO 3 and HfO 2 –WO 2 –WO 3 from 1000° to 1700° C were determined by the quenching technique using sealed sample containers. In the system ZrO 2 –WO 3 , 1:2 compound, ZrW 2 O 8 forms, having a cubic structure with a = 9.159 A. The ZrW 2 O 8 melts incongruently at 1257°± 3°C…
Crystallization and Chemical Strengthening of Stuffed β‐Quartz Glass‐Ceramics
Metastable solid solutions with the β‐quartz structure can be crystallized from most glasses in the system SiO 2 ‐Mg(AlO 2 ) 2 ‐LiAlO 2 as well as from many containing the additional components Zn(AlO 2 ) 2 Al(AlO 2 ) 3 , Li 2 ZnO 2 , and Li 2 BeO 2 . Internal nucleation is afforded by additions of ZrO 2 or TiO 2 . Ei…
Electronic Spectrum of Single Crystals of Ferricytochrome-c
The absorption spectrum of crystalline horse-heart ferricytochrome-c was investigated. Measurements were made on single crystals at room temperature from 3700 to 7600 Å using a microspectrophotometer. Molar extinction coefficients for light parallel and perpendicular to the fourfold c crystallographic axis are given.…
Ribosome-catalysed reaction of puromycin with a formylmethionine-containing oligonucleotide
In this work, the structural, electronic and absorption properties of crystalline 3′-Amino-3′-deoxyadenosine (3′-AD) under hydrostatic compression of 0–300 GPa have been studied by using density functional theory with dispersion correction. The crystal structure of 3′-AD was relaxed using three types of exchange corre…