Materials Literature
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Friction and wear of hot-pressed Si3N4 sliding on itself at low velocity (1 mm/s) were measured at room temperature in humid air, water, pure hexadecane and in hexadecane with 0.5 percent stearic acid. The friction coefficients in air and water are 0.75 and 0.65, respectively. In hexadecane with stearic acid, the fric…
Abstract Poly(elhylene terephthalate) samples were isothermally crystallized from the melt on a differential scanning calorimeter. Subsequent fusion showed three endotherms under many crystallization conditions. These three peaks are attributed to melting of crystallites formed daring primary and secondary crystalliza…
Cardiotoxicity manifested as myocardial ischemia is not generally recognized as a side effect of 5-fluorouracil. However, there have been at least 35 cases reported since 1975. In only one of these cases was a somewhat detailed evaluation done to rule out underlying coronary disease. The case reported here of 5-FU car…
The nature of the metal-ionocovalent oxide interfacial bond is discussed on the basis of different models. Predictions of these models compared to experimental results as regards the wettability of monocrystalline oxides by pure metals lead to the conclusion that interfacial bond is chemical even in non reactive syste…
In general, ionomers are ion-containing polymers [1] which, in contrast to the traditional ion-exchange resins [2], are usually rendered insoluble through the presence of crystalline do-mains. This review will be confined to a discussion of linear organic polymers having fixed ionic sidechains of exclusively either po…
ADVERTISEMENT RETURN TO ISSUEPREVArticleThermotropic liquid crystals of polyesters having a mesogenic p,p'-bibenzoate unit. 1. Smectic A mesophase properties of polyesters composed of p,p'-bibenzoic acid and alkylene glycolsJunji Watanabe and Manabu HayashiCite this: Macromolecules 1988, 21, 1, 278–280Publication Date…
A straightforward and generalizable synthesis of metal-free and metal (Cu, Co, Ni, or Fe) derivatives of a symmetrically tetrasubstituted phthalocyanine derived from 15,16-dicyano-2,3,5,6,8,9,11,12-octahydro-benzo[1,4,7,10,13]pentaoxacyclopentadecine is described. The new compounds have been characterized by elemental…
Abstract Investigations of instability of phase morphology of blends of nylons with polyethylenes and polystyrenes and the effects of “compatibilizing” additives or “agents” are described. Annealing coarsens the phase morphology of blends of nylons with polyethylenes and polystyrenes. Phase growth is observed for vari…
Pulsed fast flow reactor techniques have been used to study the reactivity of CO toward clusters of many different transition metals; V, Fe, Co, Ni, Cu, Nb, Mo, Ru, Pd, W, Ir, and Pt as well as Al, for clusters containing up to 14 atoms. Clusters are produced by pulsed laser vaporization of metal substrates, injected…
To screen a suitable polymer for preparing a controlled-release dosage form effective for one month, square plates of polyactic acid (PLA) with average molecular weights of 6000 to 50000 and copoly(lactic/glycolic) acid (PLGA) with average molecular weights of 6000 to 13500 and a copolymer ratio of 90/10 to 55/45 were…
Polylactic acid (PLA) or copoly(lactic/glycolic) acid (PLGA) microcapsules containing leuprolide acetate were prepared by an in-water drying process and the release patterns were examined in vitro. The release rates were extremely small from microcapsules prepared with PLA of average molecular weight 22500, and from m…
The superplastic behavior of the composite Y-TZP/Al{sub 2}O{sub 3} (20 wt%) in uniaxial tension has been evaluated. Large elongation (>200%) indicated superplasticity. The stress exponent and activation energy of thee composite were found to be the same order with those of Y-TZP. The flow behavior of the composite con…
The reaction of prostaglandin H synthase with prostaglandin G2, the physiological substrate for the peroxidase reaction, was examined by rapid reaction techniques at 1 degree C. Two spectral intermediates were observed and assigned to higher oxidation states of the enzymes. Intermediate I was formed within 20 ms in a…
Purified prostaglandin H synthase (EC 1.14.99.1), reconstituted with hemin, was reacted with substrates of the cyclooxygenase and peroxidase reaction. The resulting EPR spectra were measured below 90 K. Arachidonic acid, added under anaerobic conditions, did not change the EPR spectrum of the native enzyme due to high…
The discovery of the icosahedral phase, which marked the start of the new science of quasicrystals, has posed several intriguing questions for the scientific community. Verification of the unique quasiperiodic character of quasicrystals has been obtained through a series of experiments, and the nature of its structure…
The electrical resistivity of nickel, cobalt and their alloys has been measured in the temperature range from 4.2 to 1600 K. By using the s-d exchange-interaction constant and the numbers of conduction electrons and hole-carriers estimated in this study, the correlation between the magnetic resistivity and the ferroma…
The ac electrical response of the grain boundary in the ZnO–Bi 2 O 3 ‐based varistor system (in the frequency range 10 −2 ≤f≤10 7 Hz) has been analyzed using complex plane analysis techniques as a function of temperature (90°≤T≤150°C) and electric field (E 60%lmA/cm2 ≤E≤E lmA/cm2 ). The high‐temperature/field data wer…
Three specimens of Colubroidea from the locality of barrancas de Monte Hermoso , Buenos Aires Province, Argentine Republic, of Montehermosan mammal age s.l. (PIiocene) are described. Two of them are assigned to the Colubridae. The hypothesis referred to the entrance of the Colubroidea in South America are discussed
This paper describes an evaluation of various silicone-based materials as mould release agents for a polyurethane/smooth stainless steel interface. The release properties of these materials have been characterized by the use of a blister test and data are provided for peeling energies over a range of peeling velocitie…
Abstract not Available.