Materials Literature
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Abstract Novel columnar liquid crystals 5a – f bearing a dibenzo[18]crown[6] central unit have been prepared from bromodialkyloxybenzenes 1 and tetrabromodibenzo[18]crown[6] 2 via Suzuki coupling reactions. Differential scanning calorimetry (DSC) revealed that the length of the alkyl chains in the liquid‐crystalline c…
Abstract Two types of polypyrrol/molybdenum disulfide nanocomposites were prepared by means of in situ polymerization of the intercalated monomers. The nanocomposites were characterized by means of powder X‐ray diffraction, Fourier transformation infrared spectroscopy, scanning electron microscopy and transmission ele…
Liquid crystal technology has become, nowadays, one of the core technologies for implementing optical functions for WDM networks. Their advantage, with respect to other materials, is their unequalled engineering capability which is nowadays decisive in providing more flexible and cost effective systems. First, we brie…
Abstract Closed form solutions have been obtained for bubble dissolution in typical polymer melts encountered in rotational molding. The solutions are in excellent agreement with experimental data available in the literature. Using these solutions, it is shown that under typical rotational molding conditions the polym…
Tetraphenylmethane, tetraphenylsilane, and simple derivatives with substituents that do not engage in hydrogen bonding typically crystallize as close-packed structures with essentially no space available for the inclusion of guests. In contrast, derivatives with hydrogen-bonding groups are known to favor the formation…
Raman and infrared active modes of cerussite were assigned according to their symmetry species and compared to other aragonite group minerals. Small satellite bands at 823 and 1031 cm -1 on the low-wavenumber side of the fundamental vibrations ν 2 and ν 1 , respectively, have been assigned to the isotopic substitution…
Abstract Two reaction protocols are described which involve the use of polymer supports as reaction media for photooxygenation processes: 1) The use of polystyrene beads (PS) loaded with tetraphenyl‐ (TPP) or tetratolylporphyrin (TTP), swollen with the substrate in an appropriate organic solvent and subsequent irradia…
When an electrostatic probe is used to measure the surface charge on an insulating plate of constant thickness, the measuring system is regarded a shift-invariant system and the relation between the surface charge density and the probe output can be treated in the spatial frequency domain. The distribution of the surf…
The changes in the PD /spl Phi/-q-n pattern and the PD current shape due to the degradation of insulating materials have been investigated with a fast digital oscilloscope and a PD measurement system. In order to verify the effect of gas change, the volume of gas in a void was observed with the /spl Phi/-q-n pattern.…
Weakly bonded particle mixtures of mullite and alumina are assessed as candidate matrixes for use in porous matrix ceramic composites. Conditions for the deflection of a matrix crack at a fiber‐matrix interface are used to identify the combinations of modulus and toughness of the fibers and the matrix for which damage…
This review documents the application of electron backscatter diffraction (EBSD) in a scanning electron microscope to studies of grain boundaries. The EBSD technique is now applied routinely for the rapid measurement of crystallographic orientations, generally known as 'microtexture', in a variety of materials. Proces…
The engineering of biological substitutes and strategies for the replacement and/or repair of blood vessels and the components of the heart represents an important challenge for tissue engineering. In this review, the progress to date and the barriers remaining are addressed. Even though the progress has been consider…
Abstract The epoxidation of cyclooctene and 1‐octene with hydrogen peroxide was studied kinetically in HFIP (1,1,1,3,3,3‐hexafluoro‐2‐propanol)/1,4‐dioxane mixtures. In the case of cyclooctene, no additional catalyst was applied, whereas the epoxidation of 1‐octene was run in the presence of phenylarsonic acid as cata…
Polyhydroxyalkanoates (PHAs) can be divided into three main types based on the sizes of the monomers incorporated into the polymer. Short-chain-length (SCL) PHAs consist of monomer units of C3 to C5, medium-chain-length (MCL) PHAs consist of monomer units of C6 to C14, and SCL-MCL PHAs consist of monomers ranging in s…
UV-emitting phosphors find uses in various applications, such as photocopying, phototherapy, sun tanning, etc. The phosphor requirements for these applications vary. Simple methods for preparing different UV-emitting phosphors are described. Novel syntheses for some borates (SrB4O7:Eu, CeMgB5O10:Gd, GdBO3:Pr, LaB3O6:C…
Abstract Summary: Several rubber/starch composites in which the starch particles are in an amorphous state and are smaller than 1 μm, prepared by directly mixing and co‐coagulating rubber latex and starch paste, exhibit higher hardness, stress at 100%, tensile strength, and tear strength relative to the corresponding…
The structural behavior of sodalite, ideally Na 8 [Al 6 Si 6 O 24 ]Cl 2 , at room pressure and from 28 to 982 °C on heating, was determined by using in situ synchrotron X-ray powder diffraction data (λ = 0.92007(4) Å) and Rietveld refinement. The sample was heated at a rate of about 9.5 °C/min and X-ray spectra were c…
Homogeneous silicon boron oxycarbide (Si‐B‐O‐C) glasses based on SiO x C 4– x and BO y C 3– y mixed environments were obtained by pyrolysis under inert atmosphere of sol–gel‐derived precursors. Their high‐temperature structural evolution from 1000° to 1500°C was followed using XRD, 29 Si and 11 B MAS NMR, and chemical…
Conductive cotton + PANi fabrics are prepared by in-situ chemical oxidative polymer ization of aniline using ammonium persulphate as the oxidant by a process of diffusion polymerization in a mixed bath. These fabrics are characterized by elemental analysis, XRF, ATR-FTIR, WAXD, SEM, DSC, and two-probe conductivity. So…
This study compares the effect of nanosized silicon dioxide (nanosized SiO2) and microsized silicon dioxide (microsized SiO2) particles on fibrogenesis in rats. Wistar rats were instilled intratracheally with saline, 20 mg of nanosized SiO2 or 20 mg of microsized SiO2, and were sacrificed at 1 and 2 months after insti…