A significant number of molecular catalysts have been developed for electrochemical CO
reduction with high efficiency and selectivity; however, testing of these electrocatalysts in an ...application-ready system is lacking. Here, we present an example of a nonaqueous flow cell electrolyzer with Ni(cyclam)
as the homogeneous electrocatalyst for CO
reduction. Using ferrocene as a sacrificial electron donor and ammonium salts as both electrolyte and proton donor, efficient catalytic CO
reduction is achieved. The nonaqueous design shows high selectivity for the reduction of CO
to CO (>80%) and achieves high current densities with a graphite felt working electrode (up to 50 mA·cm
with 0.5 M proton donor in MeCN solution), producing >40 mL·h
of CO. The choice of a molecular electrocatalyst, solvent, and proton donor are the key factors for achieving high activity with an efficient flow electrolyzer and the eventual development of a viable continuous process.
A significant number of molecular catalysts have been developed for electrochemical CO2 reduction with high efficiency and selectivity; however, testing of these electrocatalysts in an ...application-ready system is lacking. Here, we present an example of a nonaqueous flow cell electrolyzer with Ni(cyclam)2+ as the homogeneous electrocatalyst for CO2 reduction. Using ferrocene as a sacrificial electron donor and ammonium salts as both electrolyte and proton donor, efficient catalytic CO2 reduction is achieved. The nonaqueous design shows high selectivity for the reduction of CO2 to CO (>80%) and achieves high current densities with a graphite felt working electrode (up to 50 mA·cm–2 with 0.5 M proton donor in MeCN solution), producing >40 mL·h–1 of CO. The choice of a molecular electrocatalyst, solvent, and proton donor are the key factors for achieving high activity with an efficient flow electrolyzer and the eventual development of a viable continuous process.
Silsesquioxanes as models for silica surfaces Feher, Frank J; Newman, David A; Walzer, John F
Journal of the American Chemical Society,
03/1989, Letnik:
111, Številka:
5
Journal Article
The synthesis and reactivity of monomeric, 16-electron hafnocene silyl hydride complexes are described. The complex CpCp*HfSi(SiMe3)3H (1; Cp* = η5-C5Me5), prepared by the reaction of CpCp*Hf(H)Cl ...with (THF)3LiSi(SiMe3)3, reacts rapidly with both ethylene and diphenylacetylene with elimination of HSi(SiMe3)3 to afford the corresponding hafnacyclopentane and tetraphenylhafnacyclopentadiene complexes. Complex 1 reacts with acetone to give the insertion product CpCp*Hf(OCHMe2)Si(SiMe3)3 (4). Reaction of 1 with the secondary silane H2Si(SiMe3)2 proceeds smoothly to the new silyl hydride complex CpCp*HfSiH(SiMe3)2H (5), which was characterized by X-ray crystallography. Deuterium labeling experiments indicate that the latter reaction occurs with significant scrambling of label between the SiH and HfH positions. The tertiary silane Ph3SiH does not react under comparable conditions. The silane H2Si(SiMe3)2 undergoes a similar σ-bond metathesis reaction with CpCp*HfSi(SiMe3)3Cl, to give CpCp*HfSiH(SiMe3)2Cl (7). For the latter reaction, there is a photochemical dependence on the rate and course of the reaction pathway. Exposure of the reaction mixture to room light is critical for complete conversion to 7.
Humoral immunity plays an important role against Pneumocystis jirovecii infection, yet clinical and environmental factors that impact bronchoalveolar antibody responses to P. jirovecii remain ...uncertain.
From October 2008-December 2011 we enrolled consecutive HIV-infected adults admitted to San Francisco General Hospital (SFGH) who underwent bronchoscopy for suspected Pneumocystis pneumonia (PCP). We used local air quality monitoring data to assign ozone, nitrogen dioxide, and fine particulate matter exposures within 14 days prior to hospital admission. We quantified serum and bronchoalveolar lavage fluid (BALF) antibody responses to P. jirovecii major surface glycoprotein (Msg) recombinant constructs using ELISA. We then fit linear regression models to determine whether PCP and ambient air pollutants were associated with bronchoalveolar antibody responses to Msg.
Of 81 HIV-infected patients enrolled, 47 (58%) were diagnosed with current PCP and 9 (11%) had a prior history of PCP. The median CD4+ count was 51 cells/μl (IQR 15-129) and 44% were current smokers. Serum antibody responses to Msg were statistically significantly predictive of BALF antibody responses, with the exception of IgG responses to MsgC8 and MsgC9. Prior PCP was associated with increased BALF IgA responses to Msg and current PCP was associated with decreased IgA responses. For instance, among patients without current PCP, those with prior PCP had a median 73.2 U (IQR 19.2-169) IgA response to MsgC1 compared to a 5.00 U (3.52-12.6) response among those without prior PCP. Additionally, current PCP predicted a 22.5 U (95%CI -39.2, -5.82) lower IgA response to MsgC1. Ambient ozone within the two weeks prior to hospital admission was associated with decreased BALF IgA responses to Msg while nitrogen dioxide was associated with increased IgA responses.
PCP and ambient air pollutants were associated with BALF IgA responses to P. jirovecii in HIV-infected patients evaluated for suspected PCP.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The efficacy and safety of parenteral ertapenem, a Group 1 carbapenem, 1 g once a day, for the treatment of complicated urinary tract infections (UTIs; i.e. acute pyelonephritis, UTI in men, or UTI ...associated with obstruction, foreign body or a urological abnormality interfering with normal voiding) in adults, were compared with those of parenteral ceftriaxone, 1 g once a day, in two similarly designed prospective, double-blind, randomized studies. In both studies, patients could be switched to an oral agent after ≥3 days of parenteral study therapy. At entry, 850 patients were stratified according to whether they had acute pyelonephritis or other complicated UTI without acute pyelonephritis. Two hundred and fifty-six patients in the ertapenem group and 224 in the ceftriaxone group were microbiologically evaluable. Ninety-six per cent of these patients were switched to oral therapy, usually ciprofloxacin; the median (range) duration of parenteral and total therapy, respectively, was 4 (2–14) days and 13 (14–18) days for ertapenem and 4 (2–14) days and 13 (3–17) days for ceftriaxone. The most common pathogens were Escherichia coli and Klebsiella pneumoniae, which accounted for 64.7% and 9.8% of isolates, respectively. At the primary efficacy endpoint 5–9 days after treatment, 229 (89.5%) patients who received ertapenem and 204 (91.1%) patients who received ceftriaxone had a favourable microbiological response (95% confidence interval, –7.4 to 4.0), indicating that outcomes in the two treatment groups were equivalent. Success rates in both treatment groups were similar when compared by stratum and severity of infection. The frequency and severity of drug-related adverse events were generally similar in both treatment groups. In this combined analysis, ertapenem was highly effective therapy for the treatment of complicated UTIs in adults with moderate-to-severe disease.
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