Materials Literature
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A fundamental understanding of precipitation reactions is based on information about the structural evolution of the system on all length scales and starting at the beginning of the reaction. We introduce X-ray microscopy as an additional analytical tool in order to achieve this understanding. X-ray microscopy combine…
Quantum-chemical calculations at the B3LYP level have been carried out to elucidate the reaction mechanism of the epoxidation of ethylene with the molybdenum diperoxo complex MoO(O 2 ) 2 OPH 3 . All relevant transition states and intermediates which belong to the reaction pathways suggested by Mimoun and by Sharpless…
The photophysical properties of the lowest excited singlet states, S 1 (π,π*), of two porphyrin diacids have been investigated. The diacids are H 4 TPP 2+ and H 4 OEP 2+, the diprotonated forms of free base tetraphenylporphyrin (H 2 TPP) and octaethylporphyrin (H 2 OEP), respectively. Both diacids exhibit perturbed st…
In contrast to dendrimers, hyperbranched polymers show no distinguishable interior and periphery. Hyperbranched polyglycerol, however, possesses two types of OH functionalities (arising from linear and terminal glycerol units), which can be chemically differentiated. To generate a core−shell-type architecture in hyper…
ABSTRACT: This study measured the water vapor transmission rates (WVTR) and moisture sorption of chitosan films over a range of water vapor pressures at 25 °C. Films of a constant thickness were made using chitosan with 3 levels of deacetylation. Films were tested at test relative humidity (RH) difference between RH v…
For hard ellipsoids of revolution we calculate the phase diagram for the idealized glass transition. Our equations cover the glass physics in the full phase space, for all packing fractions and all aspect ratios X0. With increasing aspect ratio we find the idealized glass transition to become primarily driven by orien…
The lattice deformation of dense strained La0.7Sr0.3MnO3 (LSMO) films is shown to control the easy direction of the magnetization. Optimized pulsed laser deposited conditions allow the fabrication of dense LSMO thin films which present an exceptional flatness with a peak–valley roughness (Rp–v) of 1 Å, associated to e…
Eight glasses with molar Mg/2Al ≈ 1 in the system MgO-Al 2 O 3 -SiO 2 have been studied by magic angle spinning (MAS) NMR spectroscopy. Using triple quantum (3Q) NMR techniques we find evidence for significant concentrations of Al coordinated to five O atoms in all glasses, the proportion increasing with decreasing Mg…
Films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blend have been annealed at a temperature above their glass transition temperatures for up to 48 h. Surface chemical compositions of the cast and annealed films were measured by X-ray photoelectron spectroscopy (XPS) while surface topographical changes wer…
Oblate and prolate ellipsoidal inorganic colloids can be synthesized by combining colloidal chemistry and ion irradiation techniques, as reported here. It is found that dramatic anisotropic plastic deformation of monodisperse silica and zinc sulfide microspheres occurs under 4 MeV Xe ion irradiation (see Figure). Poss…
A single crystal of the title compound [MnII6(H2O)9[W(V)(CN)8]4 x 13H2O]n was synthesized in a hot aqueous solution containing octacyanotungstate, Na3[W(CN)8] x 3H2O, and Mn(ClO4)2 x 6H2O. The compound crystallized in the monoclinic system, space group P2(1)/c with cell constants a = 15.438(2) A, b = 14.691(2) A, c =…
The reaction of manganese(II) and pyridine derivatives such as 3-methylpyridine (3-Mepy) and 3,4-dimethylpyridine (3,4-Dmepy) led to the new one-dimensional systems trans-[Mn(3-Mepy)2(N3)2]n (1) and trans-[Mn(3,4-Dmepy)2(N3)2]n (2). Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, a = 11.201(3) A…
We have investigated the structure and electronic properties of ferrimagnetic double perovskites, ${A}_{2}{\mathrm{FeReO}}_{6}$ $(A=\mathrm{C}\mathrm{a},\mathrm{ }\mathrm{S}\mathrm{r},\mathrm{ }\mathrm{Ba}).$ The $A=\mathrm{Ba}$ phase is cubic $(\mathrm{Fm}3m)$ and metallic, while the $A=\mathrm{Ca}$ phase is monoclin…
The synthesis of three generations of self-assembling monodendrons based on an internal AB 3 3,4,5-trisubstituted benzyl ether repeat unit containing an AB 2 3,4-bis[ p -( n -dodecan-1-yloxy)benzyloxy]benzyl ether monodendron [( 4 - 3,4 )12G1-X] attached on the periphery and the structural analysis of the correspondin…
Highly efficient electroluminescence (EL) is obtained at low operating voltage (<5 V) from n+-type silicon-electrochemically oxidized thin porous silicon–indium–tin–oxide junctions. Continuous wave external quantum efficiency greater than 1% and power efficiency of 0.37% have been achieved. Considerable reducti…
Using theorems of Fourier factorization, a recent paper [J. Opt. Soc. Am. A 13, 1870 (1996)] has shown that the truncated Fourier series of products of discontinuous functions that were used in the differential theory of gratings during the past 30 years are not converging everywhere in TM polarization. They turn out…
Flagella from diverse gram-negative bacteria induce tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) synthesis by human monocytes (F. Ciacci-Woolwine, P. F. McDermott, and S. B. Mizel, Infect. Immun. 67:5176-5185, 1999). In this study, we establish that purified flagellin (FliC or FljB), the ma…
We have investigated the formation of 2-D and 3-D superlattices of Au nanoclusters synthesized in nonionic inverse micelles, and capped with alkanethiol ligands, with alkane chains ranging from C 6 to C 18 . The thiols are found to play a significant role in the ripening of these nanoclusters, and in the formation of…
Abstract Single-crystalline photochromism of 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene was studied by X-ray crystallography. The crystal was irradiated with linearly polarized monochromatic 360 nm light and analyzed with an X-ray diffractometer. The X-Ray crystallographic analysis showed that the conversion…
Melts of ABA triblock copolymers with two different sized end blocks are examined using self-consistent field theory. At small asymmetries, the A block bidispersity reduces the stretching energy of the A domains. This effect causes a slight increase in the domain spacing and shifts the order–order transitions (OOTs) t…