Materials Literature
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Microbial biomineralization in a weathered volcanic ash deposit from the 1914 to 1915 A.D. eruption of Sakurajima volcano was investigated by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The solution chemistry of pore water was also analyzed to elucidate saturation conditions. In…
Tributyltin derivatives of 2-bromo-3-octylthiophene and 5-bromo-4-octyl-2,2′-bi(thiophene) have been selectively prepared. Condensation reactions in the presence of Pd2(dba)3(CHCl3)/4 PPh3 led to high yields (ca. 90%) of regioregular poly(3-octylthiophene) (Mw = 21.4 × 104, Mw/Mn = 1.48) and poly[4-octylbi(thiophene)]…
PII is a signal transduction protein that is part of the cellular machinery used by many bacteria to regulate the activity of glutamine synthetase and the transcription of its gene. The structure of PII was solved using a hexagonal crystal form (form I). The more physiologically relevant form of PII is a complex with…
Fourier transform infrared microspectroscopy (FTIRM) was used to investigate the organic and mineral phases of a calcified tissue (dentin) as a function of its location from predentin toward enamel. Thin dentin slices (decalcified or not) were fixed in formaldehyde and embedded in glycolmethylmethacrylate (GMA). Fixat…
The diamagnetic CeIV complex 1 is the main product of the reaction of the CeIII compounds [Ce{N(SiMe3)2}3] or CeCl3 with two equivalents of the polyhedral silsesquioxane (c-C6H11)8Si8O11(OH)2 in the presence of pyridine (py). Compound 1 is a potential homogeneous analogue of silica-supported rare earth metal catalysts…
The mode of action of essential oils from two buchu species (Agathosma betulina and A. crenulata, Rutaceae) from the Cape region of South Africa has been studied on smooth muscle in-vitro using guinea-pig ileum. At high concentration, the oils had an initial spasmogenic activity followed by spasmolysis. The spasmolyti…
Single crystals of 4.1% Cr3+ doped Cs2NaScCl6 were studied by variable temperature optical absorption and luminescence spectroscopy. The A2g4↔4T2g transition exhibits a great deal of fine structure both in absorption and emission spectra. The dynamic T⊗e Jahn-Teller effect in the Cr3+ T2g4 excited state is analyzed on…
The diffuse scattering in the diffraction pattern of the icosahedral Al-Pd-Mn quasicrystalline phase has been measured on an absolute scale by X-ray and neutron scattering on single-grain samples. Most of the diffuse scattering can be interpreted in the framework of the elasticity theory of icosahedral quasicrystals c…
The shear-induced self-diffusion and rheology of concentrated suspensions of noncolloidal hard spheres have been studied experimentally. The combined results provide an interesting physical picture. The projection of the trajectories of individual particles on the vorticity (z)–velocity (x) plane were determined throu…
A novel approach to model diffraction line shifts caused by elastic residual or applied stresses in textured polycrystals is proposed. The model yields the complete strain and stress tensors as a function of crystallite orientation, as well as the average values of the macroscopic strain and stress tensors. It is part…
Resonance Raman (RR) spectra of aggregates of tetrakis(4-sulfonatophenyl)porphyrin diacid (H 4 TSPP 2- ) excited near exciton absorption bands of 489 nm (J B band) and 421 nm (H B band) were recorded and analyzed, and RR intensities of the aggregates and segregated monomers were calculated with time-dependent resonant…
Silica gel modified with organic groups is widely used as a stationary phase for liquid chromatography. Grafting synthesis can be used to obtain stable modified silica gel surfaces. In this work, silica gel (10 nm of pore diameter and surface area of 320 m² g-1) was chemically modified with 3-chloropropyltrimethoxysil…
This paper reviews our pseudopotential approach to study the electronic structure of semiconductor quantum dots, emphasizing methodology ideas and a survey of recent applications to both “free-standing” and “semiconductor embedded” quantum-dot systems.
The development of high-throughput crystallography combined with the wealth of already accumulated information about protein crystallization properties requires constant revision of current crystallization screening procedures. Two complementary 6 × 4 matrix `clear strategy screens' (CSS) have been developed and teste…
The electronic structure of undoped and nitrogen-doped tetrahedral amorphous carbon (ta-C) has been studied using high-resolution electron energy-loss spectroscopy in transmission to determine the local bonding of the carbon and nitrogen atoms. We found that the carbon and nitrogen atoms are mainly sp3-bonded for nitr…
3D periodic microstructures of high-refractive index materials(see Figure), in particular the II–VI semiconductors CdS and CdSe, have been synthesized by electrodeposition through silica- or polystyrene-based colloidal assemblies. The highest refractive index contrast is achieved after removal of the silica or polysty…
The effect of heating rate on the sintering behavior and the piezoelectric properties of lead zirconate titanate (PZT) ceramics was investigated. Two different types of PZT (pure and doped with Nb 2 O 5 ) were sintered at 1150°C for 2 h with a wide range of heating rate (0.5°–100°C/min). The densification of pure PZT…
How fast does energy transfer along a conjugated polymer chain, and how fast between chains? A semiconducting polymer/mesoporous silica composite, which provides just enough space for one polymer chain per pore (see Figure), provides the answer through investigations of the polymer's luminescence anisotropy, with rema…
Two distinct channel systems are present in a polymer–inorganic nanocomposite, the structure of which is based on a bicontinuous plumber's nightmare (a regular array of completely interconnected tubes; see picture). Calcination at high temperatures leads to a metal oxide containing mesoporous silica-type material with…
We survey recent studies and present new data on the growth, interactions, structure and chemistry of gold deposited on TiO2(110) surfaces. The noble metal Au on TiO2(110) is a model system for weak interaction of a metal with an oxide substrate; it is also of interest because Au on TiO2 has unusually high activity as…