Synergistic antimicrobial effect of lactocin AL705 and nisin combined with organic acid salts against Listeria innocua 7 in broth and a hard cheese

The effectiveness of antimicrobial mixtures against Listeria innocua 7, used as a L. monocytogenes surrogate, was investigated in broth and a food system. Synergistic effects were found for nisin (Nis), potassium sorbate (PS), calcium propionate (CP) and sodium lactate (SL), Nis + PS being the most effective binary mixture that exhibited listericidal activity in broth. To assess the effect of adding lactocin AL705 (AL705) to Nis + organic acid salt combinations, tridimensional isobolograms were generated. Sub-MIC combinations of the antimicrobials exerted bactericidal activity against L. innocua 7 after AL705 addition to the binary mixtures. However, when applied on Sardo cheese contaminated with L. innocua 7 (initial inoculum 4.45 ± 0.06 CFU g⁻¹), only Nis + PS + AL705 produced count reductions respect to the control, reaching 3.04 ± 0.35 CFU g⁻¹ counts after 15 days at 15 °C. Ternary combinations containing AL705 showed potential to reduce antimicrobial usages for L. innocua 7 inhibition.     

两种不同界面结合强度碳/铝复合材料的内耗特性

本文研究了两种不同界面结合强度的碳/铝复合材料经不同次数加载热循环处理后的内耗值及内耗机制。弱界面结合的C/L2复合材料的内耗值变化主要由界面脱粘引起,而强界面结合的C/LD2复合材料的内耗值变化主要由位错运动所致。     

Effect of joint design on mechanical properties of AL7075 weldment

The effects of joint design on the mechanical properties of AL7075-T6 aluminum sheet were studied on the latest automated gas-tungsten arc-welding system. Using ER5356 filler metal, full-penetration welds were made on workpieces with various included joint angles. Testing of the mechanical properties of the joints was done in the as-welded, naturally aged, and postweld heat-treated conditions. The results show that by using crack-resistant filler, and by selecting the proper joint design and postweld heat treatment, strong, dependable welds can be produced on thin AL7075 sheet material. An elasticity model of the weld joint was established to help understand the mechanical behavior of the joints. An undermatched joint design is shown to be capable of achieving a joint strength that matches the strength of the base alloy.     

网络设备硬件漏洞研究

在对软件漏洞进行研究的基础上,从发掘网络设备硬件漏洞的角度对网络信息安全进行了思考.分析了网络信息安全现状,列举了当前主要的网络防御技术,分析了交换芯片AL216的组成结构和设计原理,研究了如何利用交换芯片AL216为核心设计实现以太网交换设备,并讨论了利用该芯片设计交换设备可能存在的硬件漏洞.通过论述表明了网络设备硬件漏洞存在的可行性和隐蔽性.     

复杂装备故障预测与健康管理系统初探

故障预测与健康管理(PHM)系统是新型维修保障模式—自主后勤保障的重要组成部分,对提高复杂装备的战备完好性和降低维修成本具有重要意义;首先介绍PHM系统基本概念及主要组成,并对在复杂装备全寿命周期实施PHM的必要性进行分析;综合论述了PHM系统实现中的关键支撑技术:基于RCM分析的方案设计、基于匹配度的健康状态评估和基于剩余寿命预测的维修决策;最后给出了PHM系统在无人机装备中的应用实例;国内外应用情况表明,PHM系统可显著提高维修保障效率并降低维修保障费用,可实现经济可承受性目标。     

基于DSP的机动车抗眩目系统设计

为了解决车辆在夜间行驶时,对面车灯给驾驶员造成的眩目问题,提出了一种机动车抗眩目系统的设计方案.采用视频解码芯片SAA7111A和视频编码芯片AL250完成视频信号的A/D和D/A转换;利用数字信号处理器DSP对亮度值过高的像素点进行消亮处理,以达到抗眩目的目的;可编程逻辑器件CPLD完成对整个系统的逻辑控制以及提供存储器写数据的地址.系统经实际运行,性能稳定,抗眩目效果明显.     

The influence of manganese addition on mechanical properties of commercial Al‐4Mg casting alloys

The aim of this study was to investigate the mechanical properties of Al‐Mg‐Si alloys aged to peak hardness with different dispersoid volume fraction. It was found that the tensile strength increases with dispersoid content, for alloys having similar ductility. The effect of an increasingly triaxial stress state on a fracture strain above mentioned alloys were measured using a series of notched tensile specimens whose notch root radius of curvature was changed. The alloy ductility was found to increase with dispersoid content and root radius and to decrease with increased stress triaxiality. The fracture toughness of these alloys was determined as a function of dispersoid content and notch root radius of curvature. It was observed that the fracture toughness increased as the dispersoid content and the notch root radius increased. scanning electron microscope analysis of the fracture surfaces revealed that fracture mechanism was transgranular fracture with dimples formation. It is argued that optimum mechanical properties in these alloys can be achieved at about 0.5 % Mn content.     

Study of effect of aging on martensitic transformation and tribological properties of TiNi alloy using DSC,neutron diffraction,and micromechanical probing techniques

Abstract

Recent studies have demonstrated that TiNi shape memory alloy exhibits excellent wear resistance, benefiting from their pseudoelasticity (PE) due to a thermoelastic martensitic transformation. The maximum wear resistance of the alloys corresponds to an optimum balance between the PE and hardness, which is strongly influenced by heat treatment. In this work, the effect of aging treatment on martenstic transformation behaviour, mechanical properties, including the pseudoelasticity and hardness, and wear behaviour of a Ti–51 at.-%Ni alloy was investigated using differential scanning calorimetry, neutron diffraction, and micromechanical probing techniques. The main objective of the study was to understand the aging effect on wear behaviour of the TiNi alloy and explore the mechanisms involved for further improvement of this novel tribo-alloy.     

In situ observation of recovery of lath structure in 9% chromium creep resistant steel

Abstract

The recovery process of the lath structure during tempering was investigated by in situ observations of 9% chromium creep resistant steel using TEM. A decrease of dislocation density inside the lath grains and an increase in lath width takes place during tempering. In situ observations revealed lath boundary migration and the disappearance of laths during tempering. Lath boundary migration is caused by repeat bulging and migration of local parts of the lath boundaries. Relatively small laths tend to disappear, leading to a decrease in the total energy of lath boundaries. All laths do not start to disappear at the same time; the rate of lath boundary migration differs with boundaries. The driving force of these microstructural changes is the strain accumulated by the martensitic transformation. Moreover, the recovery of the lath structure does not occur homogeneously during tempering because the strain does not distribute homogeneously in the lath structure.     

Multipass rolling of aluminium alloys: finite element simulations and microstructural evolution

Abstract

Use of numerical predictive methods such as finite element analysis is becoming progressively more common for modelling industrial hot metal working and forming processes. These tools are used not only to predict the thermomechanical behaviour of metals but increasingly to predict microstructural changes by linking them to physical models of recrystallisation and textural evolution. This paper describes the development and application of a fully integrated model for the prediction of thermomechanical and microstructural behaviour during multipass hot rolling of aluminium alloy AA 3104. Finite element code ABAQUS/standard has been used in the work and the process is modelled assuming plane strain conditions. It is shown that for this alloy the static recrystallisation which occurs during interpass cooling does not significantly influence the thermomechanical response during subsequent rolling passes.