Time-resolved measurement of dye-sensitized photocurrent at the ZnO Electrode with a nanosecond pulsed dye laser

A time-resolved dye-sensitized photocurrent of rose bengal on a ZnO electrode consisted of two components, fast (ns) and slow (μs). From the temperature dependence of the rate, the latter was found to be due to the intermediacy of shallow surface traps.     

Thermo-Optic Switch using Fluorinated Silicon Oxide and Organic Spin-on-Glass Films

A thermo-optic switch in a thin-film optical waveguide was investigated. Fluorinated silicon oxide (SiOF) and organic spin-on-glass (SOG) films were used as core-layer and clad-layer, respectively, in the waveguide structure. The SiOF films were formed at 23#x00B0;C by a liquid-phase deposition (LPD) technique using a supersaturated hydrofluosilicic acid (H₂SiF₆) aqueous solution. Thermal coefficients of the refractive indices for LPD-SiOF and organic SOG films formed on silicon (Si) substrates were #x2212;4.0 #x00D7; 10^#x2212;6/#x00B0;C, #x2212;60 #x00D7; 10^#x2212;6/#x00B0;C at the wavelength of 632.8 nm, respectively. A high extinction ratio of 15 dB was obtained for this switch at the applied voltage of 12.8 V.     

Synthetic Studies on Sialoglycoconjugates 49: Novel Disaccharides and Lactams Composed of Sialic Acid and 1-Deoxynojirimycin-Potential for Biomedical Application

Abstract

Sialic acid-containing glycoconjugates participate in a variety of biological functions on cell surfaces, not only serving as receptors for hormones, viruses and bacteria but also as mediators in cell growth, differentiation, adhesion, oncogenesis and so on. For example, influenza virus^1,2 and tripanosoma cruzi ^3,4 recognize sialic acid in the time of infection to animal cells. Recently, the sialyl-Le^x (sLe^x) and sialyl-Le^a (sLe^a) carbohydrate epitopes have been highlighted as the ligands for selectins, a family of cell adhesion molecules involved in leukocyte traffic^5,6 and tumor metastasis.⁷ 1-Deoxynojirimycin (DNJ) and related compounds are well known⁸ as the potent inhibitors of a-glycosidases and glycoprotein-processing enzymes. Some of the Nsubstituted DNJ derivatives have been noted as antidiabetic and anti-HIV agents.     

Brain site-specific proteome changes in aging-related dementia

This study is aimed at gaining insights into the brain site-specific proteomic senescence signature while comparing physiologically aged brains with aging-related dementia brains (for example, Alzheimer''s disease (AD)). Our study of proteomic differences within the hippocampus (Hp), parietal cortex (pCx) and cerebellum (Cb) could provide conceptual insights into the molecular mechanisms involved in aging-related neurodegeneration. Using an isobaric tag for relative and absolute quantitation (iTRAQ)-based two-dimensional liquid chromatography coupled with tandem mass spectrometry (2D-LC-MS/MS) brain site-specific proteomic strategy, we identified 950 proteins in the Hp, pCx and Cb of AD brains. Of these proteins, 31 were significantly altered. Most of the differentially regulated proteins are involved in molecular transport, nervous system development, synaptic plasticity and apoptosis. Particularly, proteins such as Gelsolin (GSN), Tenascin-R (TNR) and AHNAK could potentially act as novel biomarkers of aging-related neurodegeneration. Importantly, our Ingenuity Pathway Analysis (IPA)-based network analysis further revealed ubiquitin C (UBC) as a pivotal protein to interact with diverse AD-associated pathophysiological molecular factors and suggests the reduced ubiquitin proteasome degradation system (UPS) as one of the causative factors of AD.     

Photodissociation of multilayered trimethylaluminum adsorbed on a cryogenic substrate: A time-of-flight mass-spectrometric study

Photodissociation of trimethylaluminum [Al(CH₃)₃] adsorbed on a silica (SiO₂) substrate at 110 K has been studied by multiphoton ionization time-of-flight mass spectrometry. Translational energy distributions of aluminum and AlCH₃ fragments can be fitted with a composition of two Maxwell–Boltzmann distributions. The two components are attributed to different environments of photodissociating parent molecules in the multilayer.     

Laser photochemistry of organometallic compounds related to applications in microelectronics

Photochemistry of organometallic compounds achieves a marriage of a rich variety of organometallic chemistry and the full potential of electronically excited states of molecules. The application of lasers as light sources adds a great many new features to these studies, which cannot be attained by other means, because lasers provide light of such a high quality, e.g. a high-intensity, energetic (i.e. wavelength) purity, a high degree of coherence, and a high spatial and temporal resolution. Laser photochemistry of organometallic compounds, such as laser photochemical vapor deposition (LPCVD), laser ablation, and photochemical dry etching, forms the basis of many important industrial processes which sustain the present-day microelectronics industries. Lasers are used not only to photodissociate organometallic molecules, but to monitor the reaction steps by probing the starting material, chemical intermediate, or final product by many laser-based spectroscopic methods. Although it is a very young area of science (the first laser was operated in 1960), this research area is now really ebullient, as a result of strong interest from both the fundamental and the practical sides. Laser photochemistry of organometallic compounds extends a wide and fertile research frontier, full of challenge and novel possibilities. In the present review, the present status of laser (ultraviolet and visible) photochemistry of organometallic compounds related to these industrial applications is briefly reviewed, with special emphasis on the basic studies of the relevant photochemistry and their relationship to photochemical processes on solid surfaces.