Sheet metal forming of piezoceramic-metal-laminar structures—Simulation and experimental analysis

Adaptive systems with piezoelectric components offer significant opportunities for the active control of dynamic behaviour. Vibration and acoustics control as well as structural health monitoring are also possible. However ineffective production technologies prevent industrial applications. The authors are therefore proposing the integration of piezo-modules inside a double-layer sheet. The use of semi-cured adhesive avoids shear-forces being transferred to the piezo-modules during forming. After forming the adhesive will cure and the transfer of piezoelectric strain to the sheet is made possible. A detailed finite-element-model incorporating the electro-mechanical characteristics of the piezo-modules has been developed. The simulation results were validated experimentally.     

Antibiotic susceptibility of Bifidobacterium thermophilum and Bifidobacterium pseudolongum isolates from animal sources

The widespread use of antimicrobial substances has led to resistant populations of microorganisms in several ecosystems. In animal husbandry, the application of antibiotics has contributed to resistance development in pathogenic and commensal bacteria. These strains or their resistance genes can be spread along several ecological routes, including the food chain. Antibiotic resistance is important in terms of the safety of industrial strains, such as probiotics for food and feed. Bifidobacterium thermophilum and Bifidobacterium pseudolongum are known to comprise the major part of the bifidobacterial microbiota in the gut and feces of cattle and pigs. In this study, the antimicrobial susceptibility in bifidobacterial isolates of these species was investigated. Isolates from the beef and pork production chain were identified and typed to strain level, and the antimicrobial susceptibility level was tested to a set of antibiotics. Isolates with low susceptibility levels were screened by PCR for already described resistance genes. Strains atypically resistant to clindamycin, erythromycin, and tetracycline were determined. The resistance genes tet(O), tet(W), and erm(X) were detected in the bifidobacterial species that were examined.     

Enhanced biodegradation of iopromide and trimethoprim in nitrifying activated sludge

Iopromide (an X-ray contrast agent) and trimethoprim (an antibacterial drug) are frequently detected pharmaceuticals in effluents of wastewater treatment plants (WWTPs) and in surface waters due to their persistence and high usage. Laboratory-scale experiments showed that a significantly higher removal rate in nitrifying activated sludge as compared to conventional activated sludge was observed for both iopromide and trimethoprim. When the activity of the nitrifying bacteria was inhibited, the percent removal of iopromide decreased from 97 to 86% while trimethoprim removal decreased from 70 to 25%. The metabolite of iopromide identified when nitrification was not inhibited was a dehydroxylated iopromide at the two side chains. However, when the nitrifying bacteria were inhibited the metabolite identified was a carboxylate, formed during the oxidation of the primary alcohol on the side chain of iopromide. These results suggest that the nitrifying bacteria are important in the observed biodegradation of iopromide in the activated sludge with higher solid retention time (SRT). Results from the laboratory-scale study were corroborated by the observed removal efficiencies in a full-scale municipal WWTP, which showed that iopromide (ranging from 0.10 to 0.27 microg/L) and trimethoprim (ranging from 0.0.08 to 0.53 microg/L) were removed more effectively in the nitrifying activate sludge which has a higher SRT (49 days) than in the conventional activated sludge (SRT of 6 days). In nitrifying activated sludge, the percent removal of iopromide in the WWTP reached 61%, while in conventional activated sludge, average removal was negligible. For trimethoprim, removal was limited to about 1% in the conventional activated sludge, while in the nitrifying activated sludge, the removal was increased to 50%.     

Tannase activity by lactic acid bacteria isolated from grape must and wine

We examined a range of oenological lactic acid bacteria species and reference strains for their potential to degrade tannins. Bacterial tannase activity was checked by a spectrophotometric and a visual reading method. None of the strains belonging to the oenological species of the genus Lactobacillus, Leuconostoc, Oenococcus or Pediococcus were tannase producers, with the exception of Lactobacillus plantarum. All the L. plantarum strains analyzed were positive for tannase activity and their identities were reconfirmed by L. plantarum PCR-specific assay or by sequencing the 16S rDNA. Tannase activity could be considered an important criterion for the selection of malolactic starter cultures since it might confer advantages in the winemaking process by reducing astringency and haze in wine.     

Genome-wide bacterial toxicity screening uncovers the mechanisms of toxicity of a cationic polystyrene nanomaterial

By exploiting a genome-wide collection of bacterial single-gene deletion mutants, we have studied the toxicological pathways of a 60-nm cationic (amino-functionalized) polystyrene nanomaterial (PS-NH(2)) in bacterial cells. The IC(50) of commercially available 60 nm PS-NH(2) was determined to be 158 μg/mL, the IC(5) is 108 μg/mL, and the IC(90) is 190 μg/mL for the parent E. coli strain of the gene deletion library. Over 4000 single nonessential gene deletion mutants of Escherichia coli were screened for the growth phenotype of each strain in the presence and absence of PS-NH(2). This revealed that genes clusters in the lipopolysaccharide biosynthetic pathway, outer membrane transport channels, ubiquinone biosynthetic pathways, flagellar movement, and DNA repair systems are all important to how this organism responds to cationic nanomaterials. These results, coupled with those from confirmatory assays described herein, suggest that the primary mechanisms of toxicity of the 60-nm PS-NH(2) nanomaterial in E. coli are destabilization of the outer membrane and production of reactive oxygen species. The methodology reported herein should prove generally useful for identifying pathways that are involved in how cells respond to a broad range of nanomaterials and for determining the mechanisms of cellular toxicity of different types of nanomaterials.     

Solid Yttria-Stabilized Zirconia Films by Pulsed Chemical Vapor Deposition from Metal-organic Precursors

A pulsed chemical vapor deposition from metal-organic precursors (MOCVD) system was used to produce solid zirconia, and yttria-stabilized zirconia (YSZ) films. A total of six candidate metal-organic precursors for zirconia and three for yttria were investigated. Three precursor solutions for YSZ proved suitable for pulsed-MOCVD processing. Layers were deposited on metal, alumina, and porous nickel cermet substrates. Under optimal deposition conditions, precursor conversion efficiency of 90% was achieved using a solution of 3.74 vol% zirconium 2-methyl-2-butoxide + 0.42% yttium methoxyethoxide in toluene. The film growth rate was 7.5 μm·h⁻¹ at 525°C deposition temperature. Two alkoxide precursors produced YSZ layers with material costs under $0.50/(μm·cm²).     

REPLACE: a strategy for iterative design of cyclin-binding groove inhibitors

We describe a drug-design strategy termed REPLACE (REplacement with Partial Ligand Alternatives through Computational Enrichment) in which nonpeptidic surrogates for specific determinants of known peptide ligands are identified in silico by using a core peptide-bound protein structure as a design anchor. In the REPLACE application example, we present the effective replacement of two critical binding motifs in a lead protein-protein interaction inhibitor pentapeptide with more druglike phenyltriazole and diphenyl ether groups. These were identified through docking of fragment libraries into the volume of the cyclin-binding groove of CDK2/cyclin A vacated through truncation of the inhibitor peptide-binding determinants. Proof of concept for this strategy was obtained through the generation of potent peptide-small-molecule hybrids and by the confirmation of inhibitor-binding modes in X-ray crystal structures. This method therefore allows nonpeptide fragments to be identified without the requirement for a high-sensitivity binding assay and should be generally applicable in replacing amino acids as individual residues or groups in peptide inhibitors to generate pharmaceutically acceptable lead molecules.     

The circadian cycles of plasma corticosterone and adrenal cholesteryl esters in the normal and EFA-deficient female rat

In female rats subjected to a 12 hr light-12 hr darkness schedule and fed a semipurified diet containing 10% corn oil, plasma corticosterone concentration showed a monophasic circadian cycle with minimum and maximum concentrations at the start of the light and dark periods, respectively. Adrenal total cholesteryl ester concentration was inversely related to plasma corticosterone, as were those of several of the individual esters; changes in cholesteryl ester concentration appeared to follow rather than precede changes in plasma corticosterone. There was preferential depletion of the cholesteryl esters of 18∶1, 18∶2ω6, and 20∶4ω6 during glucocorticoid secretion. [Abbreviations: EFA, essential fatty acid (s);X:YωZ, fatty acid with X carbon atoms and Y olefinic bonds with the terminal double bond Z carbon atoms from the methyl group.] In female rats fed hydrogenated coconut oil (EFA-deficient), a monophasic cycle for plasma corticosterone was also observed, but the peak was much broader than that recorded for rats fed corn oil, although minima and maxima occurred at similar times for the two groups. No significant cycle of adrenal total cholesteryl esters was evident in the deficient rats, but the 20∶3ω9 and 22∶3ω9 esters did decrease significantly during the period of high plasma corticosterone concentration. Preferential net decreases in adrenal cholesteryl esters during corticosteroidogenesis were more apparent in normal than in EFA-deficient rats.