Materials Literature
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A characteristic intermediate segregation type chain length dependence of the long period D of the lamellar microdomain structure of a class of comb−coil supramolecules is reported. The supramolecular comb−coil diblock copolymers studied consist of a polystyrene (PS) “coil” block and a “comb” block of poly(4-vinylpyri…
Cationic polymerization of hexamethylcyclotrisiloxane (D 3 ) initiated by HCl and antimony pentachloride (SbCl 5 ) may give a high polymer (HP) with controlled molecular weight in high yield, and only small amounts of cyclic compounds. Theoretical M n 's were formerly obtained with D 3 using as initiator either trifli…
This paper deals with key issues of the coating technology applied to plant materials prior to osmotic dehydration and convective drying. Coatings created with solutions of starch products and pectin were examined. It was shown that coating of foods to be dehydrated influences mass transfer in a plant tissue during os…
We present a procedure for the preparation of physically realistic models of paracrystalline silicon based on a modification of the bond-switching method of Wooten, Winer, and Weaire. The models contain randomly oriented $c\ensuremath{-}\mathrm{Si}$ grains embedded in a disordered matrix. Our technique creates interfa…
A series of manganese carboxylates were prepared by reacting aqueous solutions of glycolic, lactic, oxalic, malonic, malic, tartaric or citric acids with MnO or MnO 2 at 50–70°C. A single-crystal X-ray structure of racemic manganese(II) lactate trihydrate is presented. Addition of aminoalcohols to the carboxylate comp…
Monodisperse 5-amide nylon 6 oligomers have been isothermally crystallized at 95 °C from N, N -dimethylformamide. The crystals have been investigated using optical microscopy, X-ray diffraction, electron microsopy (imaging and diffraction), atomic force microscopy and computational modeling. The diffraction signals in…
The structural and optical properties of electron beam deposited CaS:Pb thin films were investigated as a function of annealing temperature and lead concentration. X-ray diffraction measurements show weak crystallinity for such layers. Although this improves with higher annealing temperatures, no difference in the gra…
Catalytic phenol oxidation in aqueous phase under intermediate temperature and pressure has been carried out in order to determine the kinetic model of phenol uptake rate. The catalyst employed here was a commercial one based on copper supplied by Engelhard (Cu-0203T). Operational variables have been studied in the fo…
Single crystals of $p\ensuremath{-}\mathrm{GaTe}$ were grown by the Bridgman technique and characterized through x-ray diffraction, energy-dispersive x-ray analysis, x-ray photoemission spectroscopy, and transmission electron microscopy studies. The photoconductivity spectral response for in-plane conduction showed a…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationControlled Multi-Stage Recognition of Guests Using Orthogonal Electro- and Photochemical InputsAllan Goodman, Eric Breinlinger, Matthias Ober, and Vincent M. RotelloView Author Information Department of Chemistry University of Massachusetts Amherst, Massachusetts 01003 Cit…
Abstract Chitosan membranes were prepared by a solvent evaporation technique, followed by crosslinking with glutaraldehyde and coating with BSA. The effects of crosslinking and BSA coating on the pore structure of such prepared hydrogel chitosan membranes were determined. The diffusion rates of 12 non‐electrolytes ran…
The following three-dimensional structures of three forms of Escherichia coli branched-chain amino acid aminotransferase (eBCAT) have been determined by the X-ray diffraction method: the unliganded pyridoxal 5'-phosphate (PLP) form at a 2.1 A resolution, and the two complexes with the substrate analogues, 4-methylvale…
We study the structural, optical, and electrical properties of ${\mathrm{Mg}}_{z}{\mathrm{Y}}_{1\ensuremath{-}z}$ switchable mirrors upon hydrogenation. It is found that the alloys disproportionate into essentially pure ${\mathrm{YH}}_{3\ensuremath{-}\ensuremath{\delta}}$ and ${\mathrm{MgH}}_{2}$ with the crystal stru…
The entropies of a series of pure-silica molecular sieves (structural codes *BEA, FAU, MFI, and MTT) are obtained by calorimetric measurements of low-temperature heat capacity. The third-law entropies at 298.15 K are (on the basis of 1 mol of SiO 2 ): *BEA, 44.91 ± 0.11 J·K -1 ·mol -1; FAU, 44.73 ± 0.11 J·K -1 ·mol -1…
In the reaction of (η 5 -pentamethylcylopentadienyl)gallium (Cp*Ga) with B(C 6 F 5 ) 3, Ga t Bu 3, and Cp*GaX 2 (X = Cl, I) the new complexes Cp*GaB(C 6 F 5 ) 3, 1, Cp*GaGa t Bu 3, 2, and Cp*GaGa(X) 2 Cp* (X = Cl, 3; I, 4 ), respectively, were obtained. Alternatively, complex 3 was formed in the reaction of Cp*Ga with…
Abstract α,ω‐Dihydroxy‐terminated copolymeric oligomers of a 1,3‐propylene/1,4‐cyclohexanedimethylene succinate structure were obtained by the thermal polycondensation of 1,3‐propanediol/1,4‐cyclohexanedimethanol/succinic acid mixtures. They were subsequently chain‐extended via phosgene synthesis to high molecular wei…
The synthesis of peripherally tetrasubstituted phthalocyanineiron(III) chloride derivatives, (R)4PcFe(III)Cl (R=NO2, NH2, OH. and CN at the positions 2,9,16,23 or 1,8,15,22) is described. The complexes were characterized by magnetic susceptibility measurements, electronic and infrared spectra and X-ray powder diffract…
Sago starch was chemically modified through esterification using 2-dodecen-1-yl succinic anhydride (DSA) and propionic anhydride (PA) and three different solvents: [N,N dimethylformamide (DMF), triethylamine (TEA), and toluene (TOU)]. The effect of reaction times and temperatures on the modification was investigated.…
In the rotational molding of semicrystalline polymers, the slow heating and cooling rates and an almost absence of shear stresses lead to coarse spherulitic morphologies free from molecular orientation. This molding process, which is suitable for short runs of large parts, is not favorable for the dispersion of additi…
Dilatometric measurements in isobaric cooling mode were performed to study the pressure effects on the crystallization kinetics of polypropylene (PP) up to 100 MPa. The experimental specific volume curves were analyzed by taking into account the thermal gradient that appears in the sample even for relatively low cooli…