Screening and characterization of microorganisms with glutaryl-7ADCA acylase activity

A screening of microorganisms producing glutaryl-7ADCA acylase, an enzyme able to hydrolyse glutaric acid selectively from glutaryl-3-deacetoxy-7-aminocephalosporanic acid (glutaryl-7ADCA), has been carried out in soil samples. Five microorganisms expressing acylase activity were isolated and classified as Bacillus cereus, Achromobacter xylosooxidans, Bacillus sp., Pseudomonas sp. and Pseudomonas paucimobilis. The screening was carried out by preparing enrichment cultures containing glutaryl-7-ADCA or cephalosporin C as the selective carbon source. Four model compounds (adipoyl-, glutamyl- and glutaryl-p-nitroanilide and glutarylcoumarin), mimicking the glutaryl-7ADCA beta-lactam moiety, were synthesized as substrates suitable for the rapid screening of the microorganisms (2500) isolated from the enrichment cultures. A total of 300 strains were active on the model substrates and only 5 displayed acylase activity on glutaryl-7ADCA. The fermentation parameters, such as pH and inducer concentration, for the optimal acylase expression and acylase specificity towards the model substrates were different for each strain.     

Native valve infective endocarditis in elderly and younger adult patients: comparison of clinical features and outcomes with use of the Duke criteria and the Duke Endocarditis Database

The effect of age on the presentation and outcome of infective endocarditis (IE) is unclear. Many of the available data are based on analyses of mixed populations of patients including intravenous drug users or those with prosthetic valve endocarditis or native valve IE. We used the Duke criteria to compare the characteristics of 44 episodes of definite native valve IE in elderly patients (> 64 years old) with the characteristics of 64 similarly defined episodes of native valve IE in younger, nonintravenous-drug-using adult patients (> 29 years and < 60 years old). Our data suggest that the clinical presentation, characteristics, and outcome of native valve IE are similar for elderly patients and younger adult patients, although elderly patients were hospitalized an average of 12 days longer. Although we found that the occurrence of renal failure and cerebral embolism during an episode of IE was associated with higher rates of death (odds ratios, 4.8 and 4.0, respectively), age was not a significant contributor to mortality.     

Structure,stoichiometry and phase purity of strontium-doped lanthanum manganite powders

Strontium-doped lanthanum manganite La_{1, x} Sr _x MnO₃ (LSM) is characterized by hexagonal-rhombohedral distorted perovskite-type structure, deriving from the ideal cubic symmetry through rotation of the [MnO₆] octahedra around the ternary axis. The extent of distortion and unit cell volume depend on Sr content. The linear variation of the unit cell volume, observed in the compositional range 0.1 x 0.5, can be effectively used for determining the stoichiometry of LSM. A procedure for the quantitative analysis of segregated impurities (La₂O₃ and Mn₃O₄) based on X-ray powder diffraction analysis, has also been developed.     

A Comparison of Short-Term Water Demand Forecasting Models

Water Resources Management - This paper presents a comparison of different short-term water demand forecasting models. The comparison regards six models that differ in terms of: forecasting...     

Isothermal and non‐isothermal crystallization of poly(L‐lactic acid)/poly(butylene terephthalate) blends

Isothermal and non‐isothermal crystallization kinetics of poly(l ‐lactic acid)/poly(butylene terephthalate) (PLLA/PBT) blends containing PLLA as major component is detailed in this contribution. PLLA and PBT are not miscible, but compatibility of the polymer pair is ensured by interactions between the functional groups of the two polyesters, established upon melt mixing. Crystal polymorphism of the two polyesters is not influenced by blending, as probed by wide‐angle X‐ray analysis. The addition of PLLA does not affect the temperature range of crystallization kinetics of PBT, nor the crystallinity level attained when the blends are cooled from the melt at constant rate. Conversely, PBT favors crystallization of the biodegradable polyester. The addition of PBT results in an anticipated onset of crystallization of PLLA during cooling at a fixed rate, with a sizeable enhancement of the crystal fraction. Isothermal crystallization analysis confirmed the faster crystallization rate of PLLA in the presence of PBT. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40372.     

Tryptophan and tonic immobility in chickens: Effects of dietary and systemic manipulations.

Consistent with a serotonergic-midbrain raphe model of tonic immobility, 4 experiments designed to evoke changes in serum tryptophan produced reliable effects on the duration of the response in a total of 114 Production Red chickens. Systemic injections of tryptophan, the dietary precursor of serotonin, led to a dose-dependent increase in immobility, with optimal effects observed within 30 min after injection. Dietary depletion of endogenous tryptophan attenuated the duration of immobility, and a diet completely free of tryptophan, but supplemented with niacin, practically abolished the reaction. Dietary replacement of tryptophan reinstated the response. In a 5th experiment with 20 Ss, tryptamine, an alternative metabolic by-product of tryptophan, had no effect on immobility. Data are discussed in light of evidence showing serotonergic involvement in tonic immobility. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quasiparticle correction for electronic transport in molecular wires

In this paper we present calculations of ballistic transport in molecular wires. The calculations are performed using an approximated version of the GW correction in the plasmon-pole framework, which is used to improve the starting Density Functional Theory energy spectrum of the molecule between metallic leads. We show that this correction reduces the error of the correlation part for the electron energy. Finally a model with complex bands is implemented in order to get the damping regime for long polymers.     

Effect of PLL frequency synthesizer in FSK frequency-hoppedcommunications

Synthesizer transient and spur effects in an frequency-shift-keying frequency-hopped system are investigated. Models for transient analysis are developed, and resulting degradations to performance are computed. Compensation methods, such as ping-ponging multiple synthesizers and gating symbol detectors, are considered. A spur analysis is presented, and the overall output effects on hopping spectrum and demodulation are shown. Methods to bound degradation in terms of number and strength of spur lines are presented