63 research outputs found
Low-temperature deacylation of N-monosubstituted amides
No full text[GRAPHICS] The (PhO)(3)P.CL2 reagent, prepared in situ by titrating a solution of triphenyl phosphite with chlorine, is used to convert N-monosubstituted amides into their corresponding amines. The reaction, if compared to other traditional methods, shows the advantage of very mild conditions and low temperature (-30 degreesC-->rt)
(PhO)3P·Cl2-promoted bischler-napieralski-type cyclization: A mild access to β-carbolines
No full textA novel mild access to the beta-carboline skeleton is described. The reaction is a Bischler-Napieralski-type cyclocondensation, promoted by (PhO)(3)P center dot Cl-2, which is performed in dichloromethane at -30 degrees C. The products are easily obtained in good yields and do not require further chromatographic purification.A novel mild access to the β-carboline skeleton is described. The reaction is a Bischler-Napieralski-type cyclocondensation, promoted by (PhO)3P·Cl2, which is performed in dichloromethane at -30 °C. The products are easily obtained in good yields and do not require further chromatographic purification
An efficient and versatile synthesis of new Trojan-horse cephalosporins
No full textSe describe un procedimiento útil para la síntesis de nuevas cefalosporinas de doble acción. Estas
moléculas podrían representar una herramienta fascinante para el tratamiento de enfermedades infecciosas
bacterianas, ya que presentan una posible actividad inhibidora hacia las bacterias que expresan la
β-lactamasa. La principal ventaja de este enfoque sintético de tres pasos reside en su versatilidad, que permite la preparación sistemática de un amplio conjunto de nuevas moléculas.A useful synthesis of new dual-action cephalosporins is reported. These molecules could represent a
fascinating tool for treatment of bacterial infectious diseases, since they display a possible inhibitor
activity towards β-lactamase-expressing bacteria. The major advantage of this 3-step synthetic approach lies in its versatility, which allows the systematic preparation of a wide pool of new molecules
Synthesis of Trojan Horse Cefalosporins: Selection for beta-Lactamase Sensitive Bacteria
No full textAcetamidomethaneboronic acids bearing the R1 side chains of beta-lactams as inhibitors of beta-lactamase enzymes
No full textThe invention provides a method of treating a .beta.-lactam-antibiotic-resistant bacterial infection with a combination of a .beta.-lactamanalog (acylaminomethaneboronic acid deriv.). The invention also provides a method of inhibiting a .beta.-lactamase comprising contacting the .beta.-lactamase with a .beta.-lactamanalog. Finally, the invention provides compds. which are .beta.-lactamanalogs and compns. contg. .beta.-lactam analogs
Structural parameters of amylopectin clusters and semi-crystalline growth rings in wheat starches with different amylose content
No full textSmall-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) were used to investigate the internal structure of wheat starch granules with different amylose content. Different approaches were used for treatment (interpretation) of SAXS data to assess the values of structural parameters of amylopectin clusters and the size of crystalline and amorphous lamella in different wheat starches. The average values of the semi-crystalline growth rings thickness in starches have been determined and the relationship between structural characteristics and thermodynamic melting parameters is discussed. (C) 2004 Elsevier Ltd. All rights reserved
Fate of Trace Organic Contaminants in Semi-Arid Areas
No full textSemi-arid areas including the state of Nevada, has been exploring reclaimed water for direct or indirect potable reuse. Numerous research articles have discussed the occurrence of trace organic contaminants (TrOCs) in reclaimed water, surface water, soil, sediments, studied their photodegradation in water, and their transport and accumulation in plants when reclaimed water is used for irrigation. To safely reuse reclaimed water for irrigation in semi-arid areas, there is a need to determine the fate of TrOCs in various environmental media receiving reclaimed water. Therefore, the overarching goal of this dissertation was to investigate the fate of TrOCs in semi-arid areas to safely reuse the reclaimed water. To accomplish this goal, experiments were conducted to determine the fate of TrOCs in semi-arid areas. The specific objectives of this dissertation were to A) determine the fate of TrOCs in reclaimed water in an agricultural farm irrigated with reclaimed water for over 10 years, B) compare the fate of TrOCs in terminal lakes (TLs) influenced by reclaimed water to terminal lakes which are not influenced by reclaimed water, C) determine the photodegradation kinetics of TrOCs in terminal lakes and freshwater lake.To accomplish Objective A, the fate of 12 TrOCs in wastewater samples, 11 in plants and in soil pore water, and 10 in soil at an agricultural research farm were studied, which was irrigated with reclaimed wastewater for more than 10 years. Reclaimed wastewater contained 11 of 12 TrOCs, with concentrations ranging from 26 ± 9 ng/L (DEET) to 1539 ± 1899 ng/L (trimethoprim). Soils from 0 to 60 cm contained nine TrOCs from below the reporting limit (fluoxetine) to 329 ng/g (carbamazepine). TrOC concentrations decreased with increasing soil depth, except carbamazepine, which was more recalcitrant. Nine TrOCs were in the shoots and leaves of alfalfa grown in the reclaimed wastewater irrigated plots, at concentrations ranging from <1 ng/g (diphenhydramine and fluoxetine) to 49 ng/g dry weight (DW) (carbamazepine). Overall, despite some accumulation of TrOCs in the soil, alfalfa uptake was limited, which results in low exposure to foraging animals. To achieve Objective B, a preliminary assessment of the occurrence of ten TrOCs in three TLs receiving reclaimed wastewater and one TL which does not directly receive reclaimed wastewater were conducted. Concentrations of caffeine, carbamazepine, diphenhydramine, fluoxetine and meprobamate were significantly higher in TLs receiving reclaimed wastewater from a secondary treatment plant compared to those which received tertiary treated wastewater. Carbamazepine, fluoxetine, sulfamethoxazole, and trimethoprim were present at concentrations greater than is typical of other U.S. freshwater lakes, but other TrOC concentrations were at lower concentrations than in other freshwater lakes. Based on the outcomes of Objective B, carbamazepine and diphenhydramine were selected for further study because they were at higher and lower concentrations in TLs than U.S. freshwater lakes. In published literature, photodegradation of pharmaceuticals is considered as the main route of degradation of TrOCs in natural waters. To study photodegradation (Objective C), laboratory-scale solar simulated experiments were conducted on carbamazepine and diphenhydramine using surface water from terminal lakes and a freshwater lake. Photodegradation kinetics of CBZ and DPH in two terminal lakes (Walker Lake, NV and, Swan Lake, NV) were compared to the rates in one oligotrophic freshwater lake (Lake Tahoe). Dilutions of lake water samples containing 20 mg/L of CBZ and DPH were prepared and, exposed to simulated solar light for a maximum of 2 days. Photodegradation of CBZ and DPH followed a pseudo-zero order kinetics. Dissolved organic carbon up to 65 mgC/L and alkalinity of 5,198 mg CaCO3/L in terminal takes enhanced the rate of photodegradation rate of DPH and CBZ but photodegradation rates of DPH were higher than CBZ. Degradation rate constants ranged from 0.33 to 2.68 mg/L-hr for CBZ and DPH in terminal lakes compared to 0.19 to 0.88 mg/L-hr for CBZ and DPH in a freshwater lake. Overall, TrOCs were persistent at low concentrations in semi-arid areas. Water constituents in the presence of sunlight and soil have the potential to either degrade or sorb TrOCs, reducing the concentrations of aqueous and mobile TrOCs in the environment
A mechanism for biologically induced iodine emissions from sea ice
No full text© Author(s) 2015. Ground- and satellite-based measurements have reported high concentrations of iodine monoxide (IO) in coastal Antarctica. The sources of such a large iodine burden in the coastal Antarctic atmosphere remain unknown. We propose a mechanism for iodine release from sea ice based on the premise that micro-algae are the primary source of iodine emissions in this environment. The emissions are triggered by the biological production of iodide (I-) and hypoiodous acid (HOI) from micro-algae (contained within and underneath sea ice) and their diffusion through sea-ice brine channels, ultimately accumulating in a thin brine layer (BL) on the surface of sea ice. Prior to reaching the BL, the diffusion timescale of iodine within sea ice is depth-dependent. The BL is also a vital component of the proposed mechanism as it enhances the chemical kinetics of iodine-related reactions, which allows for the efficient release of iodine to the polar boundary layer. We suggest that iodine is released to the atmosphere via three possible pathways: (1) emitted from the BL and then transported throughout snow atop sea ice, from where it is released to the atmosphere; (2) released directly from the BL to the atmosphere in regions of sea ice that are not covered with snowpack; or (3) emitted to the atmosphere directly through fractures in the sea-ice pack. To investigate the proposed biology-ice-atmosphere coupling at coastal Antarctica we use a multiphase model that incorporates the transport of iodine species, via diffusion, at variable depths, within brine channels of sea ice. Model simulations were conducted to interpret observations of elevated springtime IO in the coastal Antarctic, around the Weddell Sea. While a lack of experimental and observational data adds uncertainty to the model predictions, the results nevertheless show that the levels of inorganic iodine (i.e. I2, IBr, ICl) released from sea ice through this mechanism could account for the observed IO concentrations during this timeframe. The model results also indicate that iodine may trigger the catalytic release of bromine from sea ice through phase equilibration of IBr. Considering the extent of sea ice around the Antarctic continent, we suggest that the resulting high levels of iodine may have widespread impacts on catalytic ozone destruction and aerosol formation in the Antarctic lower troposphere.Peer Reviewe
Efficacy of high voltage stimulation for healing of venous leg ulcers in surgically and conservatively treated patients
No full textSummary
Aim: Examination of the efficacy of high voltage stimulation (HVS) on healing (in various phases: decontamination, granulation, epidermization) of venous leg ulcers. Patients, material, methods: 110 persons with venous leg ulcers were included in the study. Patients in groups A and B were treated conservatively (compression and drug therapy). Patients in groups C and D were treated surgically (modified Babcock’s method). Patients in groups A and C were additionally treated with the HVS (100 μs, 100 Hz, 100 V) for 50 minutes daily, six times a week for seven weeks. Treatment progress was evaluated by observation of the number of healed wounds and measurement of the linear dimensions, area and isolated areas (covered with pus or granulation) and the volume of the leg ulcers. Results: Treatment was effective in all comparative groups. Comparison of the treatment efficacy (number of completely healed wounds) indicated statistically significant differences between groups A and B (p = 0.03), B and C (p = 0.03), B and D (p = 0.03) in favour of groups A, C and D. Comparison of other parameters supported a better therapeutic effect in groups A, C and D than in group B. There were no statistical differences in these parameters between groups A, C and D. Conclusion: The results demonstrated that HVS is an efficient method of enhancing healing in conservative treatment of venous leg ulcers. However, it appeared that HVS does not enhance healing of venous leg ulcers in patients after causal surgical treatment.</jats:p
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