Materials Literature
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A large entropy variation (magnetocaloric effect) has been discovered in ceramic perovskites with the formulas La0.65Ca0.35Ti1−xMnxO3−z and La0.5+x+yLi0.5−3yTi1−3xMn3xO3−z. Both Curie temperature and entropy change were studied from 4.2 to 400 K for different stoichiometric compositions and applied magnetic fields. Ou…
Dipole resonant x-ray scattering from ordered Mn $3d$ orbitals in $\mathrm{LaMn}{\mathrm{O}}_{3}$ has been observed near the Mn $K$-absorption edge. The polarization of the scattered photons is rotated from $\ensuremath{\sigma}$ to ${\ensuremath{\pi}}^{\ensuremath{'}}$ and the azimuthal angle dependence shows a charac…
Minimum film-formation temperature (MFFT) of vinylidene chloride (VDC)-methyl acrylate (MA) copolymer latexes prepared by batch emulsion polymerization with various compositions from 20 to 97 wt % of VDC were measured. For latexes with VDC content below 90 wt %, MFFT was similar to polymer Tg. As VDC content increased…
Moderate increases (∼ 50–75%) in the toughness of bismaleimides (BMIs) were achieved with very low-molecular-weight (∼ 1000 g/mol) imide thermoplastics at low levels of thermoplastic loading (∼ 10–20%). The thermoplastic was introduced into the BMI using a simple, one-pot, reactive solvent approach. In this approach,…
Surface carboxyl groups were formed during the 60Co γ-ray irradiation of poly(tetrafluoroethylene) (PTFE) in air. Fourier transform infrared spectroscopy enables the detection of surface carboxyl groups. The contact angles were used to calculate the dispersive and polar components of the surface free energy according…
The effects of blend composition, melt viscosity of poly(acrylonitrile-butadiene-styrene) (ABS), and compatibilizing effect of poly(methyl methacrylate) (PMMA) on mechanical properties of ABS/polycarbonate (PC) blends at ABS-rich compositions were studied. As the content of PC was increased, impact strength and Vicat…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCaged Catalytic Subunit of cAMP-Dependent Protein KinaseChung-yu Chang, Tania Fernandez, Rekha Panchal, and Hagan BayleyView Author Information Worcester Foundation for Biomedical Research Shrewsbury, Massachusetts 01545 Departments of Medical Biochemistry & Genetics a…
Thiol-passivated AgI nanoparticles of 7−15 nm were synthesized in large quantities by changing the initial molar ratio of iodide to 1-thioglycerol, and thus their competitive reaction rates with silver ions was adjusted, leading to a precise control of the final particle size. Powder X-ray diffraction and transmission…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSignificant Effects of Nonconjugated Remote Substituents in Catalytic Asymmetric EpoxidationDan Yang, Yiu-Chung Yip, Jian Chen, and Kung-Kai CheungView Author Information Department of Chemistry, The University of Hong Kong Pokfulam Road, Hong Kong Cite this: J. Am. Ch…
Latex prepared from 91 : 5 : 4 wt % vinylidene chloride-acrylonitrile-methyl acrylate monomer mixture by seeded semicontinuous emulsion polymerization was investigated for a change in minimum film-formation temperature (MFFT) during storage, with focus placed on polymer crystallinity in the dispersed state. MFFT rose…
We report the first example of intramolecular excimer formation in supramolecular trichromophoric systems resulting from the metal-directed self-assembly of chromophore-labeled ligand molecules. The trichromophoric gallium(III) chelate, ( 1 ) 3 Ga, shows an intense pyrene excimer fluorescence emission in acetonitrile,…
Peroxynitrite (ONOO - ) is a major cytotoxic agent that has been implicated in a host of pathophysiological conditions; it is therefore important to develop therapeutic agents to detoxify this potent biological oxidant, and to understand the modes of action of these agents. Water-soluble iron porphyrins, such as 5,10,…
The phase behavior of KDP, the principal material for manipulating laser radiation, has been the source of controversy and consternation. The deconvolution of the changes during heating due to genuine structural phase transitions from decomposition reactions previously has not been accomplished. Three newly characteri…
Titration curves show that the layered double hydroxide Zn2Cr(OH)6Cl, unlike Zn2Fe(OH)6Cl (shown) or Zn2Al(OH)6Cl (not shown) forms directly from solution, without the intermediacy of “MIII(OH)3”, when a mixture of metal chlorides is treated with base. Co(II), Ni(II), and Cu(II) behave similarly. Spectroscopic and tit…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTA Straightforward Synthesis of 3,4-DifluoropyrroleEric K. Woller, Valeriy V. Smirnov, and Stephen G. DiMagnoView Author Information Department of Chemistry, University of NebraskaLincoln, Lincoln, Nebraska 68588-0304 Cite this: J. Org. Chem. 1998, 63, 16, 5706–5707Publication D…
The trinuclear [Gd(3)(H(-)(3)taci)(2)(H(2)O)(6)](3+) complex has been characterized in aqueous solution as a model compound from the point of view of MRI: the parameters that affect proton relaxivity have been determined in a combined variable temperature, pressure, and multiple-field (17)O NMR, EPR, and NMRD study. T…
Density and Brillouin-scattering measurements of hydrous andesite glasses at ambient conditions showed that dissolved water has a concentration-independent partial molar volume of 12 +/- 0.5 cubic centimeters per mole and a bulk modulus of 18 +/- 3 gigapascals. Dissolved as hydroxyl ions or as molecular water, water h…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis and Application of the First Chiral and Highly Lewis Acidic Silyl Cationic CatalystMogens Johannsen, Karl Anker Jørgensen, and Günter HelmchenView Author Information Center for Metal Catalyzed Reactions Department of Chemistry, Aarhus University DK-8000 Aarhu…
[Co(bpy)3]3+ and ClO4- ions occupy the vacancies of the chiral 3-dimensional oxalate-bridged [Co2(ox)3]2- net in the compound [Co(bpy)3][Co2(ox)3]ClO4 (1). Magnetic studies for 1 and the isostructural [M(bpy)3][Co2(ox)3] [M = Fe (2) and Ni (3)] complexes show the occurrence of weak ferromagnetism in 1 (Tc = 9.0 K) and…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCones and Tubes: Geometry in the Chemistry of CarbonThomas W. EbbesenView Author Information ISIS, Louis Pasteur University, 4 rue Blaise Pascal, 67000 Strasbourg, France, and NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540 Cite this: Acc. Chem. Res.…