Materials Literature
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The harmonic-generation technique was used to measure the third-order elastic constants ${C}_{111}$ of four types of fused silica. The samples differed in amount of OH content and directional homogeneity. The results indicate that a relatively large OH content in fused silica may give rise to a relatively greater valu…
Dimeric porphyrins covalently linked directly at their periphery (β,β′-biporphyrins) or via a hydrocarbon chain (CH 2 ) n , where n = 1–8, have been synthesized from the corresponding β,β′-linked bispyrroles.
Neutron irradiation of vitreous silica produces changes of the same relative magnitude in the low-temperature excess specific heat ${C}_{\mathrm{ex}}$, the anomalous thermal conductivity $\ensuremath{\kappa}$, and the anomalous temperature dependence of ultrasonic velocity, $\frac{\ensuremath{\Delta}v}{v}$. It is ther…
Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemica…
The algal flora of a small tundra pond near Tuktoyaktuk, N.W.T., was examined during the ice-free period in 1974. A total of 166 species were identified from three communities, the euplankton, the tychoplankton, and the periphyton. The taxa containing the highest proportion of species were the Chlorophyceae, Cyanophyc…
The electrical transport properties of BaTi${\mathrm{O}}_{3}$ are discussed against the background of recent defect-chemistry investigations and in the light of the small-polaron nature of the charge carriers. Seebeck-effect measurements and chemical investigations on highly doped BaTi${\mathrm{O}}_{3}$:La ceramics ar…
The electronic properties of various types of SrTi${\mathrm{O}}_{3}$ surfaces have been studied by using ultraviolet-photoemission and electron-energy-loss spectroscopy, low-energy electron diffraction and Auger spectroscopy. Vacuum-fractured surfaces exhibit weak photoemission in the region of the bulk band gap, whic…
Abstract In grundsätzlichen Überlegungen weist der Verfasser nach, daß die nachgerade als Dogma allgemein akzeptierte Auffassung einer definierten Molekülstruktur der Materie in bestimmten Bereichen zweifelhaft ist (zum Beispiel verdünnte Gase, Molekularstrahlen), da die definierte Molekülstruktur keine zwingend notwe…
A new method is described for studying, reproducibly, the kinetics of crystallization of minerals under conditions of constant solution composition even at very low supersaturations. For calcium phosphates the method provides direct evidence for octacalcium phosphate as the precursor to hydroxyapatite precipitation at…
An analysis of the static polarizabilities of alkali halides has been presented on the basis of two potential forms for the short range repulsive interactions. The first form is that due to Born and Mayer in which the repulsive energy is considered to depend on interionic separation. The second form is that recently p…
A new species of Uronema isolated from New Jersey soils is described. The apical cell of the unbranched filament of U. trentonense is consistently pointed and a holdfast is invariably formed at the basal cell. The apical cell shows varying degrees of acumination and the holdfast exhibits several morphological forms.
It is shown that thermoelectric voltage measurements in the mixed-conduction region can be used to determine accurately the extrinsic hole concentration p 77K in Pb 0.8 Sn 0.2 Te. For the p 77K range, 10 16 -10 18 cm -3 , this can be achieved by a thermoelectric voltage measurement over the temperature range 295-395K.…
Single crystals of anthracene were grown from the melt following extensive purification efforts including liquid chromatography, sublimation and multiple zone refining in specially designed crystal growing tubes. Platelets cleaved from these crystals were tested for purity and perfection by measuring carrier yields us…
NazSzO3.5HzO, monoclinic, P2~/c, Z = 4. Cell parameters at 25 + 2°C, a = 5.9522 (9), b = 21.618 (6), c = 7.543 (3) A, fl = 103.804 (24) °, were determined by least-squares refinement from the first moments of 40 neutron diffraction Bragg reflections; 2 = 1.0155 /k based on NaC1 a 0 = 5.64037 /k. The structure was refi…
Completely analytical optimization of electronic power transformers is presented, using exponential functions of core loss, geometry, and temperature rise to determine size, optimum copper to core loss ratio, current density, flux density, and efficiency. Method applies over wide frequency range and for various core m…
K2TeIVTevIOl2 is monoclinic, space group C2/m with cell constants a = 12.360 (4), b = 7.248 (2), c = 11-967 (4) A, fl = 105-68 (2) ° and Z = 4. The structure was solved by means of Patterson and Fourier syntheses and refined to a final R value of 0.022. This structure is characterized by the five-oxygen coordination o…
A calorimeter for measuring heat output from batteries is described. The calorimeter has a peak‐to‐peak noise level of 0.3 μW. A thermodynamic analysis of battery processes is given and a method of using the calorimetric data to study and define parasitic processes is illustrated with data on several batteries.
A beam deflection system for an AUTOSCAN scanning electron microscope is described. The primary electrons (PE) are deflected in the electrostatic field of a symmetrical deflection system consisting of two trough-type travelling-wave structures with a bandwidth of 8 GHz. For routine measurements the system is driven wi…
Amorphous and semi-crystalline polypropylene samples were pyrolyzed in He from 388°-438°C and in air from 240°-289°C. A novel interfaced pyrolysis gas chromatographic peak identification system was used to analyze the products on-the-fly; the chemical structures of the products were determined also by mass spectrometr…
Many new step-growth polymers containing one or more types of linkages such as amide, ester, urea, and methanes were biodegradable by fungi and enzymes. Suitable substituents, combinations of hydrophilic and hydrophobic segments and long repeating units, contribute to the increase of biodegradability of the polymers.…