In Situ Processing of Nano Crystalline Oxide Particles/Polymer Hybrid

Nano sized crystalline particles/polymer hybrids were synthesized form designed metal-organic precursors. The newly developed method is composed of the synthesis of organic matrix by polymerization and the in situ nucleation and growth of crystalline oxide particles in the organic matrix below 100°C. The design of metal-organic precursor modified with polymerizable ligand and the selection of reaction conditions does influence the size and crystallinity of ceramic particles in organic matrix. The nano-sized magnetic particle/polymer hybrid exhibits the interesting feature of superparamagnetism and quantum size effect. The crystalline particles of BaTiO₃/, PbTiO₃/, and KNbO₃/polymer hybrids behave to be dielectric and show the typical electro-rheological behavior.     

Prolonged release of drug from triacetyl-β-CyD complex for oral and rectal administration

Triacetyl--cyclodextrin (TA--CyD), a hydrophobic cyclodextrin derivative, that is insoluble in water, was used to form a complex with flufenamic acid (FA). FA-TA--CyD complex formation was demonstrated by differential scanning calorimetry and powder X-ray diffractometry. The release rate of FA from the FA-TA--CyD complexes in phosphate buffer pH 6.8 was significantly retarded compared to that of FA from the FA and glucose mixture. When the FA-TA--CyD complexes were administered directly into the intraduodenal lumen, the plasma concentration of FA remained at a plateau level (10-18 g/ml) for 6–8 h. An increased mean residence time of FA following FA-TA--CyD complexes administration was observed. These results indicate that TA--CyD may serve as a hydrophobic carrier in prolonged-release preparations of FA.     

Flow-injection determination of d-mannitol with immobilized mannitol dehydrogenase

A flow-injection system is described for the determination of d-mannitol. Mannitol dehydrogenase is immobilized on poly(vinyl alcohol) beads and packed in a column (5 cm × 4 mm i.d.). The NADH formed is detected fluorimetrically. The response is linear between 5 × 10^?7 and 1 × 10^?4 M mannitol and the detection limit is 1 × 10^?7 M. The throughput is 30 samples per hour. The reactor is stable for at least 8 weeks.     

Stratum corneum lipid abnormalities in UVB-irradiated skin

Stratum corneum (SC) lipids are of particular importance in maintaining the permeability barrier function. Although many studies have demonstrated that UVB irradiation of mammalian skin reduces barrier function, the responsible alterations in SC lipid profiles are not known. In this study, we investigated both compositional and morphological alterations in SC lipids with the development of barrier abnormalities caused by daily UVB irradiation in hairless rat skin. The UVB irradiation of suberythemal doses (0.5 minimal erythema dose) significantly increased transepidermal water loss (TEWL) relative to nonirradiated control, indicating a diminished barrier function. Under these conditions, the total amounts of major SC lipid species (ceramides, cholesterol, free fatty acids) in UVB-irradiated SC did not differ from those in nonirradiated SC. However, electron microscopic observations revealed marked abnormalities in the intercellular domains of UVB-irradiated SC, where naturally occurring intercellular multilamellar structures were often absent and leaving the area with the appearance of an empty space. Moreover, in UVB-irradiated SC, individual corneocytes often showed small amounts of intercellular deposition product with abnormal lamellar structure, where lamellar body sphingomyelinase activity was present. These observations demonstrated a partial failure of lamellar body secretion in UVB-irradiated SC and suggested that a defect in the secretion of lamellar body-derived lipids and enzymes to SC intercellular space is, at least in part, responsible for the observed abnormal intercellular structure and barrier disruption.     

Rate constants of the O(D) reactions with N2, O2, N2O, and H2O at 295 K

Using a technique of laser flash photolysis coupled with vacuum ultraviolet laser-induced fluorescence spectroscopy, the rate coefficients of O(¹D) reactions with N₂, O₂, N₂O, and H₂O at 295 ± 2 K have been determined to be , k_O2=(4.06±0.24)×10^-11, k_N2O=(1.35±0.08)×10^-10 and . The quoted uncertainties include estimated errors and are the 95% confidence level. The k_N2 and k_N2O values obtained are larger than the current NASA/JPL recommendations by 26% and 16%, respectively, although they are still within the error limits associated with the recommendations.     

Efficient Synthesis of Polycyclic γ-Lactams by Catalytic Carbonylation of Ene-Imines via Nickelacycle Intermediates

The nickel(0)-catalyzed carbonylative cycloaddition of 1,5- and 1,6-ene-imines with carbon monoxide (CO) is reported. Key to this reaction is the efficient regeneration of the catalytically active nickel(0) species from nickel carbonyl complexes such as [Ni(CO)₃L]. A variety of tri- and tetracyclic γ-lactams were thus prepared in excellent yields with 100 % atom efficiency. Preliminary results on asymmetric derivatives promise potential in the synthesis of enantioenriched polycyclic γ-lactams.     

Simultaneous determination of silicate and phosphate in environmental waters using pre-column derivatization ion-pair liquid chromatography

A highly sensitive HPLC method for the simultaneous determination of soluble silicate and phosphate in environmental waters was developed, using ion-pair liquid chromatography preceded by the formation of their yellow α-heteropolymolybdates. The moderate-pH mobile phase enabled to use a highly efficient reversed-phase silica column. The pre-column coloring reactions at moderate-pH were reproducible for both silicate and phosphate in all quantification ranges with R.S.D.s less than 2% and 5%, respectively. The linear calibration lines between concentrations (mg-SiO₂/L and mg-PO₄/L) and peak area intensities were obtained for silicate and phosphate both with acceptable determination coefficients (r²) of 0.9999. The limits of determination for both analytes were 0.007 mg-SiO₂/L and 0.003 mg-PO₄/L, which were calculated theoretically using 10σ/slope. The four-digit dynamic ranges were obtained for 0.007-10 mg-SiO₂/L and 0.003-20 mg-PO₄/L. The developed method was applied for the analysis of tap water, river water, coastal seawater, well water, hot-spring water, commercial mineral water, and laboratory water. The results were very reasonable and acceptable from the environmental viewpoints, which were well correlated with those confirmed by the molybdenum-blue spectrophotometry.     

Structural study of self-assembled monolayers of ferrocenylalkanethiols on gold by angleresolved X-ray photoelectron spectroscopy

An angle-resolved X-ray photoelectron spectroscopic study has been performed on structures of self-assembling systems, viz ferrocenylthiols on a gold (111) crystal. The angular dependence of the intensities of photoemission reveals that ferrocenyl groups are on the outermost layer, separated from the gold substrate by hydrocarbon chains of the thiol groups.