Materials Literature
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The multicomponent self-assembly of ditopic linear ligands, circular ligands and copper(I) or silver(I) ions leads to the exclusive formation of a series of cylindrical inorganic architectures containing an internal cavity whose height may be modulated by the nature of the ligands used (see picture: 1: 20 Å; 2: 33 Å).…
Cellular materials (dense emulsions, foams, and vesicles) made out of two different phases, one being dispersed in the other, may coarsen in time through coalescence or rupturing events of the thin liquid domains that separate adjacent cells. In this Letter we study the destruction through coalescence of a model cellu…
The surface conditions favoring a negative electron affinity (NEA) on hexagonal boron nitride (h-BN) grown by radio-frequency plasma-assisted chemical vapor deposition (CVD) have been investigated by ultraviolet photoelectron spectroscopy. The NEA condition on the h-BN film appears to be resistant to oxygen-plasma or…
A liquid crystal with an azobenzene moiety as a photoactive mesogenic unit is investigated in photoinduced birefringence. Measurements reveal that it possesses large magnitude of photoinduced birefringence (Δn∼10−2) and the characteristic of long-term optical storage. The resulting polarization information can be eras…
Interwoven networks have been isolated from the self-assembly of the flexible long-chain sebaconitrile (1,10-decanedinitrile) and different silver(I) salts. These networks include an eightfold interpenetrated diamondoid frame (I), a fourfold interwoven 3D four-connected frame topologically related to the prototypical…
A novel ferromagnetic transition, accompanied by carrier density collapse, is found in doped charge-transfer insulators with strong electron-phonon coupling. The transition is driven by an exchange interaction of polaronic carriers with localized spins; the strength of the interaction determines whether the transition…
Depending on the size, the photoluminescence (PL) of silicon quantum dots present in porous silicon can be tuned from the near infrared to the ultraviolet when the surface is passivated with Si-H bonds. After exposure to oxygen, the PL shifts to the red by as much as 1 eV. This shift and the changes in PL intensity an…
Crystallization of polypropylene (PP) in unvulcanized blends of PP with the butadiene–styrene block copolymer (SBS) was studied through differential scanning calorimetry (DSC) and X-ray diffraction measurements in the composition range of 0–40 wt % SBS content. Analysis of the crystallization exotherms revealed variat…
According to Ehrenfest classification, the glass transition is a second-order phase transition. Controversy, however, remains due to the discrepancy between experiment and the Ehrenfest relations and thereby their prediction of unity of the Prigogine-Defay ratio in particular. In this article, we consider the case of…
Chaetoceros Ehrenberg, subgenus Hyalochaete Gran, section Compressa contains the species Ch. compressus Lauder 1864 and Ch. contortus Schütt 1895. On the basis of apparent intermediate forms, they were synonymized by Gran and Yendo. Rines and Hargraves suggested that they might be distinct taxa. Light and electron mic…
Species of the diatom genus Thalassiosira are an important component of the marine phytoplankton all over the world, and the Mexican Pacific Ocean planktonic flora is also rich in species of this genus. In this study 37 net plankton samples from the Gulf of Tehuantepec, Mexico were analyzed, yielding 23 taxa of the ge…
This article deals with the efficiency of using styrene (St) as a comonomer to promote the melt free radical grafting of glycidyl methacrylate (GMA) onto an ethylene and propylene rubber (EPR) in a batch mixer and a corotating self-wiping twin screw extruder. The addition of St to an EPR/GMA/peroxide system increases…
Bicomponent fibers were wet-spun from soybean protein and poly(vinyl alcohol). The protein core of the spun bicomponent fiber was brittle and showed a high frequency of core breakage upon drawing. Our effort was then to study the soybean protein solution, with the aim of trying to understand the cause for fiber brittl…
A new sampling device is used to perform near-real-time investigations of physical and chemical processes occurring inside a laboratory twin-screw extruder. Polyamide-6–ethylene propylene rubber (PA-6–EPM) blending and styrene–maleic anhydride (SMA) imidation experiments are reported in terms of morphology development…
In this work, an impact copolymer polypropylene (ICPP) was separated into 4 fractions, A, B, C, and D. The phase structure, thermal behavior, and crystalline morphology of the ICPP and its 4 fractions were studied thoroughly using scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA), differential scan…
In this work, impact copolymer polypropylene (ICPP) was fractionated into 4 fractions. ICPP and the 4 fractions were studied using Fourier transform infrared and 13C nuclear magnetic resonance analysis. The results demonstrate that fraction A is ethylene–propylene rubber, fraction B is ethylene–propylene (EP) segmente…
A series of CeO2-CaO-P2O5 glasses containing up to 35 mol% CeO2 are studied by IR and Raman spectroscopy. The spectra evaluation shows close correspondence between the IR spectra obtained and these of ultra, meta and ortho phosphates of light lanthanides. Raman spectra also evidence the formation of polymeric structur…
Polycrystalline α-alumina matrix composite fiber dispersed with YAG (yttrium-aluminum garnet, Al5Y3O12) particles have been prepared by sol-gel process using α-alumina fine seed particles. The α-alumina seed particles accelerated the crystallization of alumina matrix from θ to α phase resulting in composite fibers wit…
The contribution of the unique magneto-optical structure with the MnSb and MMnSb (M=Au, Pd) phases to the magneto-optical spectra of the composites films with various MnSb-MMnSb volume fraction was discussed in connection with the dielectric tensor analysis. As results, it was found; (1) The Mn-Sb-M (M=Au, Pd) films a…
Starting from aluminium rod stock and dopant salts, hydrothermal synthesis of pure and doped alumina powders in the temperature range of 300°-550°C and pressure range of 20–150 MPa is described.