Modelling the influence of palmitic, palmitoleic, stearic and oleic acids on apparent heat resistance of spores of Bacillus cereus NTCC 11145 and Clostridium sporogenes Pasteur 79.3

Heat resistance of spores is affected by many factors such as temperature, pH, water activity (aw) and others. Previous studies have reported that free fatty acids can affect the germination and growth of bacterial spores. In this study, we investigated the influence of free fatty acids in heating medium or in recovery medium on the heat resistance of spores of Bacillus cereus NTCC 11145 and Clostridium sporogenes Pasteur 79.3. Four free fatty acids were studied: palmitic, palmitoleic, stearic and oleic acids. During thermal treatments, the impact of these FFA in heating media was generally low, but the presence of free fatty acids in the recovery medium highly decreases bacterial spore apparent heat resistance, particularly with unsaturated fatty acids. A mathematical model was developed to describe and quantify the influence of free fatty acids in recovery media on the D-values. The z′_FFA parameter values which quantify the impact of free fatty acids were determined. The variation of this parameter value according to the free fatty acid type was compared with MIC value variation given in the literature. The model enables the decrease in D-values in the presence of free fatty acids to be estimated. The high concentrations of free fatty acids in liver or canned duck may explain the microbial stability with low sterilization values applied.     

The catalysis of the Ruff oxidative degradation of aldonic acids by titanium‐containing zeolites

Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prolonged display or rapid internalization of the IgG-binding protein ZZ anchored to the surface of cells using the diphtheria toxin T domain

We have shown previously that the diphtheria toxin transmembranedomain (T) may function as a membrane anchor for soluble proteinsfused at its C-terminus. Binding to membranes is triggered byacidic pH. Here, we further characterized this anchoring device.Soluble proteins may be fused at the N-terminus of the T domainor at both extremities, without modifying its membrane bindingproperties. This allows one to choose the orientation of theprotein to be attached to the membrane. Maximum binding to thecell surface is reached within 1 h. Anchoring occurs on cellspreviously treated with proteinase K, suggesting that T interactswith the lipid phase of the membrane without the help of cellsurface proteins. Binding does not permeabilize cells or affectcell viability, despite the fact that it permeabilizes liposomesand alters their structure. When attached to L929 fibroblasts,the proteins are not internalized and remain displayed at theirsurface for more than 24 h. When bound to K562 myeloid cells,the molecules are internalized and degraded. Thus, dependingon the cell type, soluble proteins may be anchored to the surfaceof cells by the T domain for an extended time or directed towardsan internalization pathway.     

Densification of 8Y‐Tetragonal‐Stabilized Zirconia Optoceramics with Improved Optical Properties by Y Segregation

8% Yttria‐stabilized zironcia (8YSZ) transparent ceramics have a wide technological applications. Segregation of the Y around the grain boundaries is favored by slow heating rate. The optimized sintering parameters helped in obtaining transparent ceramics of 8YSZ with a high percentage of cubic phase in addition to the presence of tetragonal phase. HRTEM was used to verify the grain growth suppression and to observe the presence of the cubic phase. The presence of cubic phase has suppressed the grain growth, which increased the transparency in the visible and infrared region without the addition of dopants or by utilizing high pressure.     

Modelling of flocculation using a population balance equation

In this paper, a model based on a population balance equation (PBE) is developed. It aims at reproducing experimental floc size distributions obtained at steady state in a jar-test. The objective is to develop a simple model, based on physical phenomena, and that does not contain any adjustable parameters. Floc size distributions obtained using a part of a particle image velocimetry (PIV) device and image analysis are used to develop mathematical expressions for the aggregation and breakage kernels. A critical volume beyond which breakage is of significant importance is identified and related to the hydrodynamics. Hydrodynamic sequencing allows the distribution of the daughter particles resulting from a breakage event to be established. The model is finally successfully validated against experimental results.     

Model selection, identification and validation in anaerobic digestion: a review

Anaerobic digestion enables waste (water) treatment and energy production in the form of biogas. The successful implementation of this process has lead to an increasing interest worldwide. However, anaerobic digestion is a complex biological process, where hundreds of microbial populations are involved, and whose start-up and operation are delicate issues. In order to better understand the process dynamics and to optimize the operating conditions, the availability of dynamic models is of paramount importance. Such models have to be inferred from prior knowledge and experimental data collected from real plants. Modeling and parameter identification are vast subjects, offering a realm of approaches and methods, which can be difficult to fully understand by scientists and engineers dedicated to the plant operation and improvements. This review article discusses existing modeling frameworks and methodologies for parameter estimation and model validation in the field of anaerobic digestion processes. The point of view is pragmatic, intentionally focusing on simple but efficient methods.     

钛基复合材料的高周疲劳性能研究

研究了TiC粒子增强的钛基复合材料的室温轴向高周疲劳性能。测试Kt=1的试样时采用的试验频率为76Hz，R＝0．06和R＝－1时，复合材料的室温疲劳强度分别为594MPa和494MPa。试验结果表明TiC粒子增强的钛基复合材料的室温高周疲劳性能与细晶组织的Ti-6Al-4V和IMI834的相当。复合材料内含有较细小的薄片状组织，这种组织为α β相互相交错构成，这种细小的α β相间的层状组织对于阻止疲劳裂纹的扩展和提高疲劳裂纹的扩展寿命有重要作用。退火后的复合材料疲劳裂纹扩展区规则且较宽广，从而也使复合材料具有较高的疲劳强度，疲劳裂纹扩展寿命延长。     

Neutronic characterization of the MEGAPIE target

The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of about 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). This project is an important step in the roadmap towards the demonstration of the accelerator driven system (ADS) concept and high power liquid metal targets in general. Following the design phase, an experimental program was defined to provide a complete characterization of the facility by performing a “mapping” of the neutron flux at different points, from the center of the target to the beam lines. The neutronic performance of the target was studied using different experimental techniques with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid lead targets used before and after the MEGAPIE experiment.     

Fuzzy Online Auto-Tuning for an Industrial PID Controller

This paper presents a fuzzy tuning system for real-time industrial PID （proportional-integral-derivative） controllers. The algorithm set the proportional gain, integral time and derivative time of a classical PID structure according to the set point, error and error derivative of the process, respectively. The tuning of the PID controller is based on a fuzzy inference machine. The set of rules of the fuzzy inference machine was obtained by experts engineering. The system is tested in an austempering process but can be applied in any industrial plant. Besides, an analysis between the response of the process with a PID controller and the system of fuzzy auto-tuning for P1D proposed was made.     

Photovoltaic collectors efficiency according to their integration in buildings

A model for building integrated photovoltaic systems has been developed and implemented in a dynamic simulation tool. This tool takes into account the thermal interactions between the PV collector and the building. The influence of the type of integration upon the PV collector efficiency has been evaluated and hybrid PV/air collectors have been studied. An overall efficiency is defined, including the production of electricity and heat. A case study has been performed on two different typical buildings. In the case of a multi-crystalline silicon PV collector integrated on the roof of a single family house located in Paris, the efficiency of unventilated PV modules fixed on the roof is 14%. If the PV collector is used to preheat the ventilation air, the efficiency reaches 20%. A proper building integration also improves the environmental balance of PV technologies over their life cycle.