Materials Literature
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The aggregations of protoporphyrin IX and haematoporphyrin IX in aqueous solutions were studied by fluorimetric techniques. Porphyrin concentrations were limited to 0.001-0.1 microM and 0.01-1 microM for protoporphyrin and haematoporphyrin respectively, where dimerization is the dominant aggregation process. The dimer…
Application of indentation fracture analysis to Knoop and Vickers indentation is examined, with particular emphasis on determining the limitations of the point force representation for the residual stress field. Deviation from the point force approximation is insignificant for crack‐size/plastic‐zone‐size ratios 1.3.…
SUMMARY. Methods for determination of low levels of biogenic silica (0.2–0.4 mg SiO 2 ) in aqueous samples after digestion with three wetalkaline extraction procedures compared favourably in both precision of replicates and recovery of silica utilized by diatoms in budgeted cultures. Leaching samples with 0.2 M NaOH f…
Continuous phase transitions were found to occur in ZrTiO 4 above and below a major discontinuity at 1125°±10°C. The space group of both forms of ZrTiO 4 is Pcnb. For specimens quenched from high temperatures, the volume of the unit cell decreases linearly from ∼1450°C to the discontinuity, with the major change occur…
Kinetic experiments involving the homogenization of fine-scale, coherent (001) pigeonite lamellae in a sub-calcic diopside have been used to constrain Ca-Mg interdifusion coefficients for clinopyroxenes. At 1150'-1250'c and 25 kbar, average Ca-Mg effective binary interdiffusion coefficients are described by D : (f .SS…
A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a hybrid plasma which is characterized by the superposition of an rf plasma and an arc jet. Calculations have been made for the confirmation of a prominent feature of the hybrid plasma. As might be expected, the deri…
We have carried out a detailed study of the smectic-$A$-smectic-$C$ transition in butyloxybenzylidene heptylaniline (40.7) using high-resolution x-ray, heat-capacity, and light scattering techniques. Although the order-parameter data are consistent with heliumlike critical behavior, the data as a whole are uniquely de…
The regional distribution of phosphoproteins whose phosphorylation is regulated either by cyclic AMP or by calcium in combination with calmodulin or phospholipid has been investigated in particulate preparations from rat CNS. About 30 distinct phosphoproteins were observed. These phosphoproteins exhibited widely diffe…
Abstract Linearly segmented polyurethanes and polyurethaneureas are known to be phase separated; one phase is the soft phase, the other, the hard domain. Quantitative evaluation of the degree of phase separation was obtained by DSC. An estimation of the dispersed soft segments outside the soft phase can be made by Δ C…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis and dilute solution properties of 12- and 18-arm-star polystyrenesJ. Roovers, Nikos Hadjichristidis, and Lewis J. FettersCite this: Macromolecules 1983, 16, 2, 214–220Publication Date (Print):February 1, 1983Publication History Published online1 May 2002Published in…
A method for determining the third-order nonlinear susceptibility of liquids using third harmonic generation (THG) is presented. A review of molecular polarizability and discussion of the relationship to susceptibilities are presented. All materials, including air and windows of the liquid cell, can make substantial c…
A method for the electrodeposition of thin films of cupric hexacyanoferrate on glassy carbon and tin oxide electrodes has been devised. At low scan rates, in , these films exhibit nearly ideal cyclic voltammetric current‐potential waves with a peak potential of +0.69V vs. SCE on glassy carbon. Similar to the Prussian…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSilver nitrate impregnation of preparative silica gel columns for liquid chromatographyMakota. Morita, Susumu. Mihashi, Hideji. Itokawa, and Shoji. HaraCite this: Anal. Chem. 1983, 55, 2, 412–414Publication Date (Print):February 1, 1983Publication History Published online1 M…
Abstract Literature data on the average molecular weights M n , M W , M z , and/or M v for several polymers indicated that they fell outside the continuum originally proposed to model molecular weight distribution (MWD), where the log‐normal (LN) distribution, or positively valued Gex parameters m and k , define the c…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCorrelation between metal stability, charge transfer, and Raman frequencies in metalloporphyrins and their π-π complexesJ. A. ShelnuttCite this: J. Am. Chem. Soc. 1983, 105, 4, 774–778Publication Date (Print):February 1, 1983Publication History Published online1 May 2002Publ…
The process of glass formation is discussed from several perspectives. Particular attention is directed to kinetic treatments of glass formation and to the question of how fast a given liquid must be cooled in order to form a glass. Specific consideration is paid to the calculation of critical cooling rates for glass…
Crystals are sectioned, polished, etched in fluoboric acid and coated with a layer of reflecting substance. Surface relief corresponds to Ab/An compositional structure. Zones as thin as 0.5 mu m and with compositional contrast of about 1 percent An can be resolved using the method.--Modified journal abstract.
<div class="htmlview paragraph">A Ceramic Fiber Reinforced Aluminum Matrix Composite has been developed that has excellent wear resistance, seizure resistance against cast iron, good thermal conductivity and high strength at elevated temperatures, By strengthening top land and top ring groove of piston with the…
<div class="htmlview paragraph">To aid in better assessing the corrosion performance of AZ91 die cast magnesium, standard salt spray corrosion tests have been made on both randomly selected commercial die castings and on three series of controlled purity test panels. The results reveal that the poor performance…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeterojunction silicon/indium tin oxide photoelectrodes: development of stable systems in aqueous electrolytes and their applicability to solar energy conversion and storageG. Hodes, L. Thompson, J. DuBow, and K. RajeshwarCite this: J. Am. Chem. Soc. 1983, 105, 3, 324–330Pub…