Materials Literature
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Abstract Chitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular inter…
Spiders (Araneae) spin high-performance silks from liquid fibroin proteins. Fibroin sequences from basal spider lineages reveal mosaics of amino acid motifs that differ radically from previously described spider silk sequences. The silk fibers of Araneae are constructed from many protein designs. Yet, the repetitive s…
Low-frequency Raman spectra of a diblock copolymer of polystyrene and polyisoprene (PS−PI) and a polystyrene−polybutadiene blend (PS−PB) have been studied. Low-frequency features, viz., the quasi-elastic lines, Boson peaks, and vibrational lines, if present, have been fitted to known theoretical expressions. It has be…
Polarized and depolarized Brillouin scattering experiments on molten ZnCl2 were performed between 300 and 600 degrees C in different geometries. VV spectra measured in backscattering and small angle scattering were analyzed with conventional viscoelastic theory using either a Debye or a Cole-Davidson model for the mem…
The optical absorption spectra of CaS:Eu,Sm at several concentrations of Eu (from 0 to 0.05 mol%) were examined to clarify the electron trapping mechanism for its photo-stimulated luminescence. Corresponding to the electron and hole trapping states, the difference between the absorption spectra after and before excita…
We have investigated the charge-ordering (CO) behaviour of the layered manganites La 2-2 x Sr 1+2 x Mn 2 O 7 (0.3⩽ x ⩽0.8) by means of transport and magnetization measurements. It is found that the CO transitions occur in the very high-temperature region (200-340 K) and moreover the re-entrant CO behaviours are exhibi…
We have investigated $3d$ electronic states of doped transition metals in II-VI diluted magnetic semiconductors ${\mathrm{Zn}}_{1\ensuremath{-}x}{M}_{x}\mathrm{Se}(M=\mathrm{Mn},\mathrm{F}\mathrm{e},\mathrm{C}\mathrm{o})$ and ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}Y(Y=\mathrm{Se},\mathrm{Te}),$ using the tr…
The kinetics of pressure-induced phase separation (PIPS) in solutions of polyethylene ( M w = 108 000, PDI = 1.32) in n -pentane has been studied using time- and angle-resolved light scattering. Controlled pressure quench experiments were conducted at different polymer concentrations (0.49, 0.97, 2.07, 2.8, 4.1, 5.0,…
[reaction: see text]. An approach to the asymmetric intramolecular meta photocycloaddition of phenoxyalkenes is described. The beta-cyclodextrin complexes of several phenoxyalkenes have been synthesized and irradiated in the solid phase. The effect of the CD-hosting on the regio- and enantioselectivity is discussed. V…
The vinyloxycyclophosphazene derivatives, N 3 P 3 Cl 5 OCH CH 2 ( 1 ) and N 4 P 4 Cl 7 OCH CH 2 ( 6 ), undergo radical polymerization to produce the highly functionalized homopolymers [CH(ON 3 P 3 Cl 5 )CH 2 ] n ( 7 ) and [CH(ON 4 P 4 Cl 7 )CH 2 ] n ( 8 ). These materials undergo a remarkable two-step thermal decompos…
Abstract The emulsion polymerization of methyl methacrylate in the presence of chitosan with potassium persulfate (KPS) as an initiator was examined in a previous article. The free radicals that dissociated from KPS not only initiated the polymerization but also degraded the chitosan molecules. Therefore, in addition…
We report the synthesis and characterization of a new class of materials based on combining hydrolytically degradable polyesters and fluorocarbon surface chemistry. These materials have surface properties which overcome some of the limitations of polymeric materials in controlled cellular or tissue adhesion properties…
M\"ossbauer spectrometry was carried out in the range of temperature from 4 K to well above the Curie temperature on polycrystalline ceramics of ${A}_{2}{\mathrm{FeMoO}}_{6}$ $(A=\mathrm{C}\mathrm{a},\mathrm{S}\mathrm{r},\mathrm{B}\mathrm{a}).$ A secondary component in all the paramagnetic or ferromagnetic spectra is…
Novel aromatic poly(thioether−ketone)s ( PTEKs ) bearing the 2,6-dimethyl-1,5-naphthylene units were synthesized by the polycondensation of aromatic dihaloketones and aromatic dithiols in the presence of K 2 CO 3 . PTEKs with molecular weight ( M n ∼ 65 000, M w ∼ 350 000) were obtained in quantitative yields. The mol…
Metallic alloys: ferrous alloys (ferritic and martensitic) austenitic stainless steels nickel-based alloys for resistance to aqueous corrosion nickel-based alloys for resistance to high-temperature corrosion corrosion of copper and its alloys reactive and refractory alloys aluminium alloys magnesium alloys. Intermetal…
A new method of grafting conjugated polymers onto solid substrates by self-assembled monolayers (SAM) and electrochemistry is described. The polyfluorene was designed to have the carbazole group as the pendant group to offer electropolymerizability. As has been studied, carbazole is easily electropolymerized by cyclic…
We use molecular-dynamics simulations in two dimensions to investigate the possibility that a core-softened potential can reproduce static and dynamic anomalies found experimentally in liquid water: (i) the increase in specific volume upon cooling, (ii) the increase in isothermal compressibility upon cooling, and (iii…
Hydroxyl-terminated poly(amidoamine) (PAMAM) dendrimers of generation 2−4 (G n -OH, n = 2, 3, and 4; M r ∼ 3.7, 6.9, and 14.3 kDa, respectively) and dendrimers encapsulating Cu 2+ ions have been investigated by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. Umbelliferone (7-h…
Photocatalytic activity of lanthanide tantalates, LnTaO 4 (Ln = La, Ce, Pr, Nd, and Sm), for water splitting was studied in connection to the effect of Ln 4f levels on the electronic structure. Valence band XPS, UV−vis, and first-principle electronic calculations suggested that the position of Ln 4f levels becomes low…
ADVERTISEMENT RETURN TO ISSUEPREVCommentNEXTComment on the Relationship of the Pyramidalization Angle at a Conjugated Carbon Atom to the σ Bond AnglesR. C. HaddonView Author Information Departments of Chemistry and Chemical & Environmental Engineering, University of California at Riverside, Riverside, California 92521…