Susceptibility of Escherichia coli O157 to chitosan‐arginine in beef liquid purge is affected by bacterial cell growth phase

Here, we evaluated the impact of bacterial growth stage on the effect of chitosan‐arginine (Ch‐arg) on Escherichia coli O157:H7 cell numbers and metabolic activity within contaminated beef juice held at room temperature. Using a lux‐marked metabolic reporter strain of E. coli O157:H7, the results showed that Ch‐arg was most bioactive against cells in the lag phase and exponential phase. In comparison, there was a reduced, although still significant, inhibitory effect of Ch‐arg on the viability and metabolic activity of E. coli O157 held in stationary phase. Ch‐arg reduced, but did not eliminate E. coli O157 growth in the meat juice over 48 h. Based on the evidence presented here and elsewhere, we conclude that Ch‐arg can limit the growth and activity of food spoilage bacteria; however, it cannot completely eliminate bacterial contaminants originally present. Ch‐arg should therefore be viewed as a potentially protective measure rather than a biocidal agent that completely eliminates the risk of pathogen transfer in the food chain.     

On the Certification of Bonded Repairs to Primary Composite Aircraft Components

Airworthiness certification is required when bonded repairs are made to primary composite structure in situations where damage has reduced or has the potential to reduce residual strength to below the design ultimate strength. Generally, certification of bonded primary structure poses many difficulties. As most repairs are one-off events meeting these certification requirements is especially challenging since demonstration by testing will generally not be possible or cost-effective. This paper discusses options for addressing the two key issues relating to certification: (a) how to validate initial and enduring bond strength of adhesive bonds, mainly given the inability of conventional non-destructive inspection to provide this assurance and (b) how to develop acceptable generic design allowables for bonded repairs which represent actual failure modes – especially for cyclic loading, since validation by testing of simulated repairs will generally be infeasible. It is concluded that proof testing of bonded repair coupons is a promising approach for validating bond strength and fatigue testing of representative bond joint specimen can provide generic allowables for patch design. For hidden structure or very high value repairs structural health monitoring of repairs based on a strain-transfer approach offers considerable promise.     

Laser and GTAW torch processing of Fe–Cr–B coatings on steel

A comparison has been made of the relationship between microstructure and microhardness developed by surface melting Nanosteel SHS 7170 Fe–Cr–B alloy powder onto a plain carbon steel surface. This powder was initially developed as a high velocity oxyfuel sprayed coating, giving a strength 10 times that of mild steel, and is particularly suitable for surface protection against wear and corrosion. In the present study, the alloy powder was injected into the laser melted surface, while a preplaced powder was melted using the gas tungsten arc welding (GTAW) technique. The laser track consisted of fine dendrites and needle-like microstructures, which produced a maximum hardness value of over 800 HV, while the GTAW track produced a mixture of equiaxed and columnar grain microstructures with a maximum hardness value of 670 HV. The lower hardness values are considered to be associated with dilution and grain size.     

△∑转换器中的转换时延

小信号传感器通常生成慢速移动的DC信号。对这类传感器来说,△∑ADC就可以作为完整的高分辨率、低噪声解决方案,而无需大部分模拟输入电路。一些系统采用多个传感器,这些传感器要求输出端带多路复用器的高分辨率、低噪声ADC相匹配。例如,汽车诊断应用就是一种多路夏用传感器系统,其通过焱多小信号传感器监控温度、胎压、气囊就绪情况等（如图1所示）。     

Inducing Energetic Switching Using Klotho Improves Vascular Smooth Muscle Cell Phenotype

The cardiovascular disease of atherosclerosis is characterised by aged vascular smooth muscle cells and compromised cell survival. Analysis of human and murine plaques highlights markers of DNA damage such as p53, Ataxia telangiectasia mutated (ATM), and defects in mitochondrial oxidative metabolism as significant observations. The antiageing protein Klotho could prolong VSMC survival in the atherosclerotic plaque and delay the consequences of plaque rupture by improving VSMC phenotype to delay heart attacks and stroke. Comparing wild-type VSMCs from an ApoE model of atherosclerosis with a flox’d Pink1 knockout of inducible mitochondrial dysfunction we show WT Pink1 is essential for normal cell viability, while Klotho mediates energetic switching which may preserve cell survival. Methods: Wild-type ApoE VSMCs were screened to identify potential drug candidates that could improve longevity without inducing cytotoxicity. The central regulator of cell metabolism AMP Kinase was used as a readout of energy homeostasis. Functional energetic switching between oxidative and glycolytic metabolism was assessed using XF24 technology. Live cell imaging was then used as a functional readout for the WT drug response, compared with Pink1 (phosphatase-and-tensin-homolog (PTEN)-induced kinase-1) knockout cells. Results: Candidate drugs were assessed to induce pACC, pAMPK, and pLKB1 before selecting Klotho for its improved ability to perform energetic switching. Klotho mediated an inverse dose-dependent effect and was able to switch between oxidative and glycolytic metabolism. Klotho mediated improved glycolytic energetics in wild-type cells which were not present in Pink1 knockout cells that model mitochondrial dysfunction. Klotho improved WT cell survival and migration, increasing proliferation and decreasing necrosis independent of effects on apoptosis. Conclusions: Klotho plays an important role in VSMC energetics which requires Pink1 to mediate energetic switching between oxidative and glycolytic metabolism. Klotho improved VSMC phenotype and, if targeted to the plaque early in the disease, could be a useful strategy to delay the effects of plaque ageing and improve VSMC survival.     

Direct comparison of Eulerian–Eulerian and Eulerian–Lagrangian simulations for particle-laden vertical channel flow

Particle-laden flows in a vertical channel were simulated using an Eulerian–Eulerian, Anisotropic Gaussian (EE-AG) model. Two sets of cases varying the overall mass loading were done using particle sizes corresponding to either a large or small Stokes number. Primary and turbulent statistics were extracted from these results and compared with counterparts collected from Eulerian–Lagrangian (EL) simulations. The statistics collected from the small Stokes number particle cases correspond well between the two models, with the EE-AG model replicating the transition observed using the EL model from shear-induced turbulence to relaminarization to cluster-induced turbulence as the mass loading increased. The EE-AG model was able to capture the behavior of the EL simulations only at the largest particle concentrations using the large Stokes particles. This is due to the limitations involved with employing a particle-phase Eulerian model (as opposed to a Lagrangian representation) for a spatially intermittent system that has a low particle number concentration.     

Dielectric studies of the effect of water on the relaxation properties of nitroglycerine-nitrocellulose mixtures

Dielectric relaxation and water adsorption data are reported on mixtures of nitrocellulose and nitroglycerine which have been exposed to moisture to varying degrees. It was observed that the characteristics of these systems depend on the level of nitrogen in the base polymer. At 10.9% hydroxyl sites still exist which can effectively interact with the moisture, whereas at 12.9% the free hydroxyls appear to be incorporated into the ordered semi-crystalline regions of the polymer. The addition of water to nitroglycerine-nitrocellulose mixtures has little effect on the dominant beta relaxation other than to narrow the distribution of relaxations. The relaxation process is, in this case, associated with a cooperative relaxation of nitroglycerine moieties. Water has the effect of decreasing the cooperativity of the beta relaxation process.     

Lycopene from two food sources does not affect antioxidant or cholesterol status of middle-aged adults

Background

Epidemiological studies have reported associations between reduced cardiovascular disease and diets rich in tomato and/or lycopene. Intervention studies have shown that lycopene-containing foods may reduce cholesterol levels and lipid peroxidation, factors implicated in the initiation of cardiovascular disease. The objective of this study was to determine whether consumption of lycopene rich foods conferred cardiovascular protection to middle-aged adults as indicated by plasma lipid concentrations and measures of ex vivo antioxidants.

Methods

Ten healthy men and women consumed a low lycopene diet with no added lycopene (control treatment) or supplemented with watermelon or tomato juice each containing 20 mg lycopene. Subjects consumed each treatment for three weeks in a crossover design. Plasma, collected weekly was analyzed for total cholesterol, high density lipoprotein cholesterol (HDL-C) and triglyceride concentrations and for the antioxidant biomarkers of malondialdehyde formation products (MDA), plasma glutathione peroxidase (GPX) and ferric reducing ability of plasma (FRAP). Data were analyzed using Proc Mixed Procedure and associations between antioxidant and lipid measures were identified by Pearson's product moment correlation analysis.

Results

Compared to the control diet, the lycopene-containing foods did not affect plasma lipid concentrations or antioxidant biomarkers. Women had higher total cholesterol, HDL-C and triglyceride concentrations than did the men. Total cholesterol was positively correlated to MDA and FRAP while HDL-C was positively correlated to MDA and GPX. GPX was negatively correlated to triglyceride concentration.

Conclusions

The inclusion of watermelon or tomato juice containing 20 mg lycopene did not affect plasma lipid concentrations or antioxidant status of healthy subjects. However, plasma cholesterol levels impacted the results of MDA and FRAP antioxidant tests.