Preparation,XAFS Characterization,and Catalysis of Platinum Nanowires and Nanoparticles in Mesoporous Silica FSM-16

Pt nanowires are prepared in mesoporous FSM-16 by photoreduction of H₂PtCl₆, while H₂-reduction of H₂PtCl₆/FSM-16 at 673 K gives Pt nanoparticles in FSM-16. The Pt nanowires and nanoparticles are characterized by physicochemical methods such as XAFS, TEM, XRD, and XPS. The formation mechanism of the Pt nanowires and the catalytic performance in the water–gas-shift reaction are also investigated.     

Catalyst Preparation Using Supercritical Carbon Dioxide: Preparation of Rh/FSM-16 Catalysts and Their Catalytic Performances in Butane Hydrogenolysis Reaction

Supported Rh catalysts on FSM-16 were prepared by treating FSM-16, impregnated with [Rh(OAc)₂]₂ in supercritical carbon dioxide at 398 K and 30.3 MPa, followed by calcination and hydrogen reduction. The resulting Rh/FSM-16 catalysts were characterized by CO chemisorption, XRD, TEM, FTIR and EXAFS, and catalytic performances of the Rh/FSM-16 were tested in butane hydrogenolysis reaction. It is demonstrated that highly dispersed Rh particles are obtained by the supercritical CO₂ treatment. In the hydrogenolysis reactions, the supercritical CO₂-treated catalyst showed higher conversions and ethane formation.     

Bone mineral density in women using depot medroxyprogesterone acetate for contraception

OBJECTIVE: To evaluate the possible effects of depot medroxyprogesterone acetate injectable contraception on bone mineral density in reproductive-age women. METHODS: We conducted a population-based cross-sectional comparison of bone mineral density levels in women using depot medroxyprogesterone acetate contraception and in women of similar age not using this method. The study recruited 457 nonpregnant women aged 18-39 years who were enrollees of a Washington state health maintenance organization. One hundred eighty-three women were receiving injections and 274 were not. Bone mineral density at several anatomic sites (spine, femoral neck, greater trochanter, and whole body) was measured using dual-energy x-ray absorptiometry. Data on other factors potentially related to bone density were collected through questionnaire and examination. RESULTS: Overall, age-adjusted mean bone density levels were lower for users of this method than for nonusers at all anatomic sites: The mean difference was 2.5% for the spine (P = .03) and 2.2% for the femoral neck (P = .12). Exposure to depot medroxyprogesterone acetate continued to be significantly (P < .01) associated with decreased bone density at the femoral neck, spine, and trochanter after multivariate adjustment for other risk factors related to bone density. Age-specific comparisons indicated that the major differences in bone density between users and nonusers occurred in the youngest age group (women 18-21 years); the mean femoral neck bone density was 10.5% lower (P < .01) for the exposed women, and differences were consistent (P < .01) across all anatomic sites. We also noted a significant dose-response relation between longer use of depot medroxyprogesterone acetate and decreased bone density levels in this age group (P < .01 for all sites). CONCLUSION: These results provide evidence that contraception with depot medroxyprogesterone acetate, particularly long-term use, may adversely affect bone mineral density levels in young women aged 18-21 years. The implications for future bone health need further study.     

Rho-associated kinase of chicken gizzard smooth muscle

Rho-associated kinase (Rho-kinase) from chicken gizzard smooth muscle was purified to apparent homogeneity (160 kDa on SDS-polyacrylamide gel electrophoresis) and identified as the ROKalpha isoform. Several substrates were phosphorylated. Rates with myosin phosphatase target subunit 1 (MYPT1), myosin, and the 20-kDa myosin light chain were higher than other substrates. Thiophosphorylation of MYPT1 inhibited myosin phosphatase activity. Phosphorylation of myosin at serine 19 increased actin-activated Mg+-ATPase activity, i.e. similar to myosin light chain kinase. Myosin phosphorylation was increased at higher ionic strengths, possibly by formation of 6 S myosin. Phosphorylation of the isolated light chain and myosin phosphatase was decreased by increasing ionic strength. Rho-kinase was stimulated 1.5-2-fold by guanosine 5'-O-3-(thio)triphosphate.RhoA, whereas limited tryptic hydrolysis caused a 5-6-fold activation, independent of RhoA. Several kinase inhibitors were screened and most effective were Y-27632, staurosporine, and H-89. Several lipids caused slight activation of Rho-kinase, but arachidonic acid (30-50 microM) induced a 5-6-fold activation, independent of RhoA. These results suggest that Rho-kinase of smooth muscle may be involved in the contractile process via phosphorylation of MYPT1 and myosin. Activation by arachidonic acid presents a possible regulatory mechanism for Rho-kinase.     

Microbial conversion of palmitoleic acid to 9,12-hexadecadienoic acid (16:2ω4) by Trichoderma sp. AM076

Trichoderma sp. AM076, isolated from a freshwater sample, was found to accumulate 9,12-cis-hexadecadienoic acid (16:2ω4), when grown with palmitoleic acid (16: 1ω7). Methyl myristate was the best carbon source for the conversion of palmitoleic acid to 16:2ω4. The mycelial 16:2ω4 content reached 17.4 mg/g dry mycelia (443 mg/L) when the fungus was grown in a medium that contained 2.0% methyl myristate, 1.5% yeast extract, and 2.0% methyl palmitoleate, pH 6.0, for 5 d at 28°C with shaking. In both nonpolar and polar lipids from the mycelia, 16:2ω4 was detected as one of the major fatty acids when 16:1ω7 was added. It is probable that 16:1ω7 is converted to 16:2ω4 through the Δ12 desaturation reaction.     

Surface Oxidation and Subsurface Microstructure Evolution of Alloy 690TT Induced by Partial Slip Fretting Corrosion in High-Temperature Pure Water

The surface oxidation and subsurface microstructure evolution of Alloy 690 TT can occur during partial slip fretting corrosion in high-temperature pure water.Detailed characterization methods such as laser scanning confocal microscopy,scanning electron microscopy,electron probe micro-analyzer,and transmission electron microscopy were used to reveal the related mechanism.The results showed that Cr_2 O_3 oxides together with a small number of spinel oxides were formed in sticking region since a small quantity of high-temperature water could pass through the gaps between the asperities to oxidize the materials.Widespread distribution of oxides in microslip region consisted of(Ni,Fe)Cr_2 O_4,because Ni~(2+) and Fe~(2+) ions could react with Cr_2 O_3 to generate a small amount of non-stoichiometric spinel oxides.The oxides around micropitting in microslip region consisted of double-layer structure.The outermost layer contained(Fe,Cr)-rich oxides due to the effect of fretting leading to mechanical mixing between Cr_2 O_3 and(Ni,Fe)(Fe,Cr)_2 O_(4.)The inner layer consisted of(Fe,Ni)-rich oxides owing to the consumption of Cr_2 O_3 by the reaction with Ni~(2+) and Fe~(2+) ions.The reciprocating motion of oxide particles in microslip region resulted in the stress-strain supporting the recrystallization for the formation and development of a tribologically transformed structure in subsurface and plowing effect by fretting in surface.     

Functional associations between two estrogen receptors, environmental estrogens, and sexual disruption in the roach (Rutilus rutilus)

Wild male roach (Rutilus rutilus) living in U.K. rivers contaminated with estrogenic effluents from wastewater treatment works show feminized responses and have a reduced reproductive capability, but the chemical causation of sexual disruption in the roach has not been established. Feminized responses were induced in male roach exposed to environmentally relevant concentrations of the pharmaceutical estrogen 17alpha-ethinylestradiol, EE2 (up to 4 ng/ L), during early life (from fertilization to 84 days posthatch, dph), and these effects were signaled by altered patterns of expression of two cloned roach estrogen receptor (ER) subtypes, ERalpha. and ERbeta, in the brain and gonad/ liver. Transactivation assays were developed for both roach ER subtypes and the estrogenic potencies of steroidal estrogens differed markedly at the different ER subtypes. EE2 was by far the most potent chemical, and estrone (E1, the most prevalent environmental steroid in wastewater discharges) was equipotent with estradiol (E2) in activating the ERs. Comparison of the EC50 values for the compounds tested showed that ERbeta was 3-21-fold more sensitive to natural steroidal estrogens and 54-fold more sensitive to EE2 as compared to ERalpha. These findings add substantial support to the hypothesis that steroidal estrogens play a significant role in the induction of intersex in roach populations in U.K. rivers and that the molecular approach described could be usefully applied to understand interspecies sensitivity to xenoestrogens.     

Antimicrobial resistance types and genes in Salmonella enterica infantis isolates from retail raw chicken meat and broiler chickens on farms

Salmonella enterica subsp. enterica serotype Infantis isolates from retail raw chicken meat (n = 98) and broiler chickens on farms (n = 70) were examined for antimicrobial susceptibility and antimicrobial resistance genes. A total of 15 antimicrobial resistance types, 14 in meat and 10 in broiler isolates, were identified, and 9 of the 15 types were indistinguishable between meat and broiler isolates. Resistance to both oxytetracycline and dihydrostreptomycin accounted for 94.0% of the resistance types in meat and broiler isolates, and each type harbored aadA1 within 1.0 kb of class 1 integron and tetA. Of nalidixic acid resistance types, point mutations at 87Asp (GAC) to Tyr (TAC) in the quinolone resistance-determining region of gyrA was detected in 10 of 13 meat isolates and at 87Asp to Asn (AAC) in four of seven broiler isolates. These findings suggest that the antimicrobial resistance of Salmonella Infantis in retail chicken meat predominantly originates from broiler chickens.