Materials Literature
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Specific volumes and thermal pressure coefficients (∂p/∂T)v of 5CB, 7CB, 50CB, and 80CB were measured from temperatures near their crystalline melting points to above their nematic-isotropic transitions. At TNI, volume changes ΔV of 0.52, 0.67, 0.25, and 0.48 cm3 mol−1, respectively, were found. A discontinuity of 0.0…
Abstract Simultaneous chemical polymerization and oxidation of pyrrole have been initiated by organic electron acceptors, 2,3‐dichloro‐5,6‐dicyano‐ p ‐benzoquinone (DDQ) and tetrachloro‐ o ‐benzoquinone(chloranil). The polypyrrole (PPY) complexes so produced are semiconductive and granular in nature. For the PPY–DDQ a…
(111) twins are found frequently in the microstructure of BaTiO 3 ceramics prepared by the mixed‐oxide technique. The processing steps by which the (111) twins are formed are in question. A BaCO 3 ‐TiO 2 powder mixture is milled and then Calcined at 1100°C for 2 h, where BaTiO 3 is formed by the release of CO 2 . Afte…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIonic conductivity in branched polyethylenimine-sodium trifluoromethanesulfonate complexes: comparisons to analogous complexes made with linear polyethylenimineCaroline S. Harris, Mark A. Ratner, and Duward F. ShriverCite this: Macromolecules 1987, 20, 8, 1778–1781Publicatio…
Abstract The synthesis of three cyclic imino ethers containing mesogenic groups attached to the heterocyclic unit through flexible spacers is described. Cationic ring‐opening isomerization polymerization of two of them, i.e., 2‐[4‐(4‐methoxy‐4′‐biphenyloxy)butyl]‐2‐oxazoline (MeOBiph‐4‐Oxz) and 2‐[6‐(4‐methoxy‐4′‐biph…
We analyze the dynamics of a transient pattern formation in the Fr\'eedericksz transition corresponding to a twist geometry. We present a calculation of the time-dependent structure factor based on a dynamical model which incorporates consistently the coupling of the director field with the velocity flow and also the…
Six Twin dimeric compounds having two rigid cores connected by a central spacer group are described. Two types of rigid units, 4-pentyloxyphenyl cinnamates and 4-cyano-4-oxybiphenyl, were employed. The spacer groups were pentamethylene (PM), diethylene oxide (EO) and disiloxane (DS). For each rigid core the nematic-is…
Only a few years ago image simulation of HRTEM images were mostly carried out as low priority jobs on large mainframe computers with images available the next day as overprinted characters on computer paper. Today the same calculation can be carried out on a dedicated workstation in a matter of minutes with output on…
Abstract Poly(phenylene sulfide) (PPS) and poly(ether etherketone) (PEEK) are high performance engineering thermoplastics with a unique combination of excellent environmental, mechanical, and thermal properties. Research on the thermal and rheological properties of PPS and PEEK resins and carbon fiber reinforced prepr…
Abstract The content of the largest filler particles and their agglomerates has been evaluated in polypropylene‐calcium carbonate composite. A strong decrease of tensile impact strength was noted with the increasing value of Av, i.e. the ratio of area belonging to inclusions greater than about 10 μm to the overall are…
A method for predicting yarn strength and strain is presented, based on the main fiber parameters of linear density, length, strain, and stress. The application of special software for a microcomputer makes the time required for all the calculations extremely short (2 minutes maximum). A comparison of the theoretical…
We have carried out high-resolution x-ray scattering and heat-capacity studies of the nematic (N)\ensuremath{\rightarrow}smectic-A (SmA) transitions in 4'-(4''-n-alkoxybenzyloxy)-4-cyanostilbene with the alkyl chain of length 7 (T7) and 8 (T8). The material T7 exhibits only a single nematic--to--smectic-${A}_{1}$ tran…
Two techniques are presented for the extraction of the individual intensities of completely overlapping reflections in a powder diffraction pattern. The first is analogous to Sayre's [ Acta Cryst. (1952). 5 , 60–65] squaring method while the second is based upon maximizing the entropy of the Patterson function subject…
La phase incommensurable de [N(CH 3 ) 4 ] 2 [ZnCl 4 ] cristallise dans le groupe de superespace Pmcn. Affinement de la structure jusqu'a 0,052. La phase «lock-in» cristallise dans le groupe d'espace P2 1 cn. Affinement jusqu'a 0,075
Advances in machine learning have impacted myriad areas of materials science, such as the discovery of novel materials and the improvement of molecular simulations, with likely many more important developments to come. Given the rapid changes in this ...Read More
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEquilibria and UV spectra of mono- and polynuclear molybdenum(VI) speciesJ. J. Cruywagen and J. B. B. HeynsCite this: Inorg. Chem. 1987, 26, 16, 2569–2572Publication Date (Print):August 1, 1987Publication History Published online1 May 2002Published inissue 1 August 1987https…
A kinetic study of the aging behavior of tetragonal zirconia polycrystals (TZPs) from 100° to 500°C suggests that there exists a cricital grain size of 0.52 μm below which the tetragonal symmetry can be retained. Property degradation of TZPs at low temperatures is connected with transformation‐induced microcracking. I…
Increasing the cooling rate from the melt has been found to increase the rate of slow crack growth at 42°C. For various histories of cooling rate, annealing and specimen geometries, the initiation rate increased when the density decreased. The effect of residual stresses on slow crack growth was separated from the eff…
Rapidly quenched Nd-Fe-B magnets show a pronounced composition dependence of the intrinsic coercivity HcI which increases with increasing Nd content to values of 23.5 kOe. The magnetic hardening is ascribed to a Nd-rich phase located at the phase boundaries of the Nd2Fe14B grains. Samples prepared by crystallization o…
Optimal anticancer treatment with cell cycle-specific antimetabolites requires maintenance of a cytotoxic drug level for a prolonged period of time. We explored the use of multivesicular liposomes as a slow-release depot of 1-beta-D-arabinofuranosylcytosine for intrathecal administration. The intrathecal half-life of…