Materials Literature
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Synthesis of cage and ladder silsesquioxanes by the dehydration of silanols using dicyclohexylcarbodiimide (DCC) is described. The reaction of 1,3-dicyclohexyldisiloxane-1,1,3,3-tetraol with DCC gave octa(cyclohexylsilsesquioxane) in 13% yield. The bicyclic ladder siloxane 3 (Ph 8 Thex 2 Si 6 O 7 ) was prepared from 1…
In this study we have quantified the ionic content and volume of native aquatic, and two cultured bacteria, by X-ray microanalysis (XRMA) in the transmission electron microscope (TEM). The cellular concentrations of magnesium (means of 630 and 710 mM) were more than an order of a magnitude higher than the outside conc…
Abstract Two Mg-Al spinels (FAS1 and FAS2) in high-grade hornfels from the Toal de Mason skarn (Predazzo Monzoni, NE Italy) were investigated by means of single crystal X-ray diffraction and electron microprobe analysis in order to evaluate the last intra-crystalline closure temperature. The evidence provided by cryst…
This paper extends a moving screw dislocation theory in a conventional crystal to a one-dimensional hexagonal quasicrystal in the framework of the Landau theory. By introducing two functions φ and ψ which satisfy wave equations, respectively, a general solution is suggested in terms of φ and ψ. The analytical expressi…
The copolymerization of glycolide with ε-caprolactone was performed in the presence of tin octoate at moderate temperatures (100 and 150°C). The influence of the conditions (comonomer ratio, temperature) on the chain microstructure of the obtained copolymers was examined. Transesterification was found to affect consid…
A detailed analysis of the structure of glycolide/ε-caprolactone copolymers was performed using 13C and 1H NMR. All methylene and carbonyl carbons of glycolidyl and caproyl units in the 13C NMR spectra were found to be sensitive to the microstructure. The 1H NMR spectra allow not only to determine the copolymer compos…
The enthalpy of formation of kaolin polymorphs at 298 K has been determined by dropsolution calorimetry into molten lead borate at 975 K. Corrections have been made for impurities in the samples. The standard enthalpy of formation from the elements is: kaolinite -4120.2 ± 6.6 kJ/mol, dickite -4107.6 ± 5.7 kJ/mol, nacr…
High-resolution electron-microscopy (HREM) images from different hydroxyapatite (OHAp) samples showed p3 projection symmetry along [001] instead of the p6 projection symmetry compatible with the space group P6_3/m of OHAp. Image processing was used to establish without ambiguity that threefold symmetry dominates the i…
This paper deals with homogeneous and heterogeneous primary nucleation and the atomistic model of heterogeneous primary and secondary nucleation. Three aspects of crystal growth mechanisms will be taken into account: growth by two-dimensional nucleation, the so-called birth and spread model, spiral growth without and…
Three processing routes have been used to prepare barium titanate powders, namely conventional coprecipitation, single‐microemulsion coprecipitation using diether oxalate as the precipitant, and double‐microemulsion coprecipitation using oxalic acid as the precipitant. A single‐phase perovskite barium titanate was obt…
A series of bentonite illite/smectite with a range of Fe content (0.08-0.95 atoms per half formula unit) and illite composition (3-97 percent illite) has been analyzed by means of FTIR, ^27^ Al MAS NMR, and theoretical calculations by reverse Monte Carlo simulations to study cation distribution in the octahedral sheet…
Amorphous vanadium pentoxide has been investigated as an intercalation material for Li‐ion batteries due to its high specific energy and high capacity for Li intercalation. However, the rate of insertion is typically limited by lithium diffusion in the host and by its modest conductivity. The present work demonstrates…
The electronic state of $\ensuremath{\kappa}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{2}\mathrm{Cu}[\mathrm{N}(\mathrm{CN}{)}_{2}]\mathrm{Br}$ is precisely controlled around the superconductor-insulator boundary by partial deuteration. As the salt approaches the boundary with progressive deuteration,…
Porous silica fibers were synthesized by templating activated carbon fibers using supercritical fluid as a solvent. A precursor of silica, tetraethyl orthosilicate was dissolved in supercritical CO 2 and attached to the base-activated carbon. The base-activated carbon in the sample coated with SiO 2 was removed by cal…
Thin films (1−200 nm) of the title compounds were prepared by vapor deposition on glass at a controlled temperature. Film growth was studied in situ by optical absorption spectroscopy and measurement of the electrical conductivity. Independent of substrate temperature, a layered growth was found for ultrathin films of…
The nature of the magnetic and structural phase transitions in the Heusler alloy Ni 2 MnGa is studied by numerical calculations of the electronic structure, generalized susceptibility, and various Fermi-surface cross sections.
Abstract High-resolution transmission electron microscopy (HRTEM) examinations have indicated that three types of surface layers may exist in natural kaolinite crystals. Type 1 has the expected 7-Å surface layer as terminations. Type 2 has one 10-Å pyrophyllite-like (or low-charge beidellite-like) layer as the surface…
The rostral epithelium of a newly metamorphosed juvenile of Branchiostoma floridae was examined at the EM level to confirm previous reports on its sensory cells. The majority of the sensory cells are of three types: two type I variants, with simple collars of unbranched microvilli surrounding their cilia, and one kind…
Diagnosis of microbiologically influenced corrosion on iron‐containing substrata exposed in marine environments cannot be based solely on spatial relationships between large accumulations of bacterial cells and iron corrosion products. Experiments were designed to evaluate the relationship between marine bacteria and…
We report the first direct measurements of ultrafast electronic relaxation dynamics in PbI 2 colloidal nanoparticles using femtosecond transient absorption spectroscopy. The PbI 2 nanoparticles were prepared using colloidal chemistry methods in different solvents, including ethanol, 2-propanol, 1-butanol, water, and a…