Star‐like polyurethane hybrids with functional cubic silsesquioxanes: Preparation,morphology, and thermomechanical properties

Star‐like polyurethane (PU) hybrid films containing octafunctional cubic silsesquioxanes are prepared by polyaddition reaction between octakis(dimethylsilyloxy) silsesquioxane isopropenyldimethylbenzyl isocyanate (OS‐PDBI) and octakis(dimethylsilyloxy) hydroxypropyl silsesquioxane (HPS); and between OS‐PDBI and hexane diol (HD). The effect of incorporation of nanostructured cubic silsesquioxanes (CSSQ) on the macroscopic properties of PU film and their thermomechanical properties are investigated. The obtained hybrid films are relatively transparent. Their morphologies and properties are studied by using Fourier transform infra‐red spectroscopy (FTIR), X‐ray diffraction (XRD), atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and contact angle measurements. The formation of urethane linkage disrupts the three‐dimensional ordered structure of CSSQ in the hybrid film. AFM images show clearly that no phase separation in the macroscopic level for both PU hybrid films. TGA and DMA analyzes indicate that the incorporation of octafunctional silsesquioxane in PU hybrid film provides enhanced thermal stability and increased crosslink density. Moreover, the existence of cage structure also improves oxidation resistance and mechanical strength. The incomplete reaction between OS‐PDBI and HPS due to the steric hindrance of highly branched rigid CSSQ could result in a slight decrease in initial decomposition temperature. Furthermore, hardness and out‐of‐plane compressive modulus are also investigated by nanoindentation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4602–4616, 2009     

Evaluation of vaginal malodor and efficacy of treatment by high performance ion exchange chromatography

High performance ion exchange chromatography was employed to evaluate the presence of short chain organic acids in the vaginal fluid of a woman troubled by persistent foul vaginal odor, but who did not have typical bacterial vaginosis. The vaginal secretions from this patient were collected on a weighed cotton swab and eluted into water and extracted by acidified ether. Salts of the acids were back-extracted into aqueous solution and chromatographed on an H-form resin column and compared to commercially available standards. A strikingly large amount of caproic acid was found. The caproic acid disappeared after metronidazole therapy, and a subsequent follow-up chromatogram showed a predominance of lactic acid. The success of this technique in evaluating the present case suggests that such a method may prove useful in other types of vaginal infection.     

Effect of Ca doping level on the laser-induced voltages in tilted La1−x Ca x MnO3 (0.1 ≤ x ≤ 0.7) thin films

Tilted La_1?x Ca _x MnO₃ (0.1 ≤ x ≤ 0.7) thin films have been grown on vicinal cut LaAlO₃ (100) substrate by pulsed laser deposition. The laser-induced voltage effect was studied at room temperature with the KrF excimer laser using as the thermal source. The relationships between Ca doping level and voltage signal, response time and anisotropy Seebeck coefficient were established. The voltage signal and anisotropy Seebeck coefficient increase at first with increasing Ca doping level, reach a maximum at the same Ca content around x = 0.5, and then decrease. The respond time decreases with the Ca concentration increasing, and changes very little after x = 0.5. The figure of merit F _m was also the largest at this doping level, indicating a potential good performance of the photodetector devices. The variation of intrinsic structural and transport anisotropy induced by the change of Ca concentration has been proposed to account for the different LIV effects observed in LCMO thin films.     

Preparation and thermomechanical properties of epoxy resins modified by octafunctional cubic silsesquioxane epoxides

The thermomechanical properties of octafunctional cubic silsesquioxane‐modified epoxy resins associated with dicycloaliphatic hardener (4,4′‐dimethyldiaminodicyclo hexyl methane) were studied using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The structures of epoxy resin containing cubic silsesquioxane epoxides were characterized by Fourier transform infrared spectroscopy and wide‐angle X‐ray scattering techniques. In this work, octa(dimethylsiloxybutylepoxide) octasilsesquioxane (OB), and octa(glycidyldimethyl‐siloxyepoxide) octasilsesquioxane (OG), were synthesized and used as additives to improve the properties of a commercial epoxy resin by exploring the effects of varying the ratio of OB or OG. The commercial Ciba epoxy resin (Araldite LY5210/HY2954) was used as a standard. It was found, by thermogravimetric analysis and dynamic mechanical analysis, that the highest thermal stability was observed at N = 0.5 (N = number of amine groups/number of epoxy rings). No glass transition temperature was observed by adding 20 mol % OB to the Ciba epoxy resin, indicating the reduction of chain motion in the presence of octafunctional cubic silsesquioxane epoxide. The storage modulus of the OB‐modified epoxy resin also increased, especially at higher temperatures, compared with the Ciba epoxy resin under identical curing conditions. Fourier transform infrared data elucidated the preservation of cubic silsesquioxane structure after curing at high temperature. In contrast, the OG/Araldite LY5210/HY2954 systems gave poorer thermomechanical properties. The low viscosity of OB at room temperature (～ 350 cPs) makes it suitable for composite processing and, when used in conjunction with the Ciba epoxy, lowers the viscosity of this system as well. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3490–3503, 2004     

Nitroprussidkalium als Eiweissreagens

Ohne Zusammenfassung     

CSF from Parkinson disease Patients Differentially Affects Cultured Microglia and Astrocytes

Background  

Excessive and abnormal accumulation of alpha-synuclein (α-synuclein) is a factor contributing to pathogenic cell death in Parkinson's disease. The purpose of this study, based on earlier observations of Parkinson's disease cerebrospinal fluid (PD-CSF) initiated cell death, was to determine the effects of CSF from PD patients on the functionally different microglia and astrocyte glial cell lines. Microglia cells from human glioblastoma and astrocytes from fetal brain tissue were cultured, grown to confluence, treated with fixed concentrations of PD-CSF, non-PD disease control CSF, or control no-CSF medium, then photographed and fluorescently probed for α-synuclein content by deconvolution fluorescence microscopy. Outcome measures included manually counted cell growth patterns from day 1-8; α-synuclein density and distribution by antibody tagged 3D model stacked deconvoluted fluorescent imaging.     

Synthesis of (±)-cis-tetradec-5-en-4-olide — The racemate of the sex pheromone of the Japanese beetle

A three-stage method has been developed for the stereoselective synthesis of (±)-cis-tetradec-5-en-4-olide — the racemate of the sex pheromone of the Japanese beetlePopillia japonica C. The key reactions used were the stereoselective cis reduction of a triple bond with the aid of heterogeneous hydrogenation catalysts (zinc-copper couple, nickel boride, Lindlar catalyst) and the radical lactonization of conjugated systems by the action of acetic acid in the presence of manganese acetate.Institute of Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. All-Union Scientific-Research Institute of Chemical Agents for Plant Protection. Tartu State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 98–102, January–February, 1984.     

Highly efficient luminescent organic clusters with quantum dot-like properties

Organic clusters with uniform structure and size have been synthesized and studied. The quantum confinements on organic arms [chains shorter than exciton Bohr radii (aB)] have been confirmed by the discrete energy levels from PLE, narrow PL lines, size effect from UV, and spherical shape from TEM, as well as Raman peaks red-shifting and broadening. The results indicate the materials have QD-like properties.