PEF Assisted Thermal Sterilization （PEF-ATS） Process-Inactivation of Geobacillus sterothermophilus Spores

An improvement to existed methods of microbial spore inactivation is presented in this paper. A treatment chamber was designed to hold elevated temperatures （above 100℃） and pressure in the range of （3 atm）. The innovative thermal assisted pulsed electric fields （PEF-ATS） processing was applied to inactivate Geobacillus sterothermophilus ATCC 10149 spores suspended in simulated milk ultrafiltrate （SMUF） of 50% （wt/wt） concentration. G. stearothermophilus spores are extremely resistant to high temperature and are also proven to be resistant to PEF processing in the range of 35 kv/cm. However, the combination of PEF and high temperature treatment conducted in this work shows significant inactivation of the G. stearothermophilus spores. A processing temperature/time of 115 ℃/3.7 sec with an electric field intensity of 45 kv/cm showed 4.1 Iogmicrobial reductions, which are significantly less than usually obtained in thermal treatment alone.

基于动态矩阵控制的比值控制新算法

在Hagglund的调和比值控制(Blend Station)算法的基础上,提出一种基于动态矩阵控制(DynamicMatrix Control,DMC)的比值控制新算法。给出该算法的详细推导过程,并通过多个仿真实例将该算法的控制效果与固定比值控制、基于PI的自适应比值控制效果进行比较,仿真结果证实了该算法的有效性。

Porosity Effects on Interlaminar Fracture Behavior in Carbon Fiber-Reinforced Polymer Composites

Fiber-reinforced polymer composite materials have become materials of choice for manufacturing application due to their high specific stiffness, strength and fatigue life, low density and thermal expansion coefficient. However, there are some types of defects such as porosity that form during the manufacturing processes of composites and alter their mechanical behavior and material properties. In his study, hand lay-up was conducted to fabricate samples of carbon fiber-reinforced polymer composites with three different vacuum levels in order to vary porosity content. Nondestructive evaluation, destructive techniques and mechanical testing were conducted. Nondestructive evaluation results showed the trend in percentages of porosity through-thickness. Serial sectioning images revealed significant details about the composite’s internal structure such as the volume, morphology and distribution of porosity. Mechanical testing results showed that porosity led to a decrease in both Mode I static interlaminar fracture toughness and Mode I cyclic strain energy release rate fatigue life. The fractographic micrographs showed that porosity content increased as the vacuum decreased, and it drew a relationship between fracture mechanisms and mechanical properties of the composite under different modes of loading as a result of the porosity effects. Finally, in order to accurately quantify porosity percentages included in the samples of different vacuum levels, a comparison was made between the parameters and percentages resulted from the nondestructive evaluation and mechanical testing and the features resulted from fractography and serial sectioning.

Preface on “Biomaterial Foundations of Therapeutic Delivery”

Driven by the enormous clinical need,drug delivery systems（DDS）have become a prime research focus in the field of biomaterials.They offer opportunities for developing new therapeutic approaches to prevent and treat debilitating and life-threatening diseases.Smart biomaterials,whether synthetic or naturally-derived,

Outstanding high-temperature oxidation-and wear-resistance of WC based cermets

The interaction between oxidation and frictional load can greatly deteriorate the performance of ceramic-metal composites.In this work,we used WC-Co cermet as a representative of ceramic-metal composites to study its wear failure behavior and protection effectiveness.It is found that a transition of wear mechanism from mechanical wear to oxidative wear occurs with increasing temperature.The addition of zirconia can significantly improve the anti-oxidation performance and load-bearing capacity of the cermet under the frictional load.This is mainly attributed to the modulation of the tribo-oxide layer constitutions and changes in surface morphology.The zirconia component facilitates the formation of a dense protective oxide layer and reduces the content of brittle oxides on the worn surface.Based on the understanding of the temperature-and oxidation-induced compositional and microstructural evolutions at the sliding contact surface and subsurface,a promising approach is proposed for developing ceramic-metal composites with high wear resistance and anti-oxidation capability.

Effect of doping Gd^(3+) on crystal structure and luminescent properties of Sr_2SiO_4:Eu^(2+) phosphor

Sr1.995-1.5xGdxSiO4：0.005Eu^2＋ phosphor series with x=0-0.08 mol for near-ultraviolet white light-emitting diodes （NUV w-LEDs） were synthesized via solid-state reaction method. XRD profile pattern and refinement results demonstrated that doping Gd^3＋ ions resulted in the phase transformation （β-Sr2SiO4→α＇-Sr2SiO4）. The photoluminescenee spectrum of the sample with x=0 tool displayed two emission peaks centered at 470 and 525 nm. The two-peak spectra became one-peak spectra with the Gd^3＋ concentration increasing. Actually, the fitting results demonstrated that the one-peak spectra were still composed of two single emission spectra. The photoluminescence intensity was improved and the CIE chromaticity coordinates were adjusted via doping Gd^3＋.

Effect of friction stir processed microstructure on tensile properties of an Al-Zn-Mg-Sc alloy upon subsequent aging heat treatment

An as-cast Al-Zn-Mg-Sc alloy was friction stir processed varying tool related parameters, yielding microstructures with different grain sizes （0.68, 1.8 and 5.5 μm）. Significant increases in room temperature ductility were obtained in these materials with reasonable enhancement in strength. It is demonstrated that the type of microstructure produced by friction stir processing （FSP） has a significant influence on the choice of post-FSP heat treatment design for achieving improved tensile properties. It is also found that the ultrafine grained FSP material could not achieve the desired high strength during the post-FSP heat treatment without grain coarsening, whereas the micro-grained FSP materials could reach such strength levels （〉560 MPa） under conventional age hardening heat treatment conditions.

Preparation of Different Silane-modified Silicalite-1 Membranes and Their Pervaporation Properties for Aqueous Ethanol Solution

A multi-layer mesoporous silicalite-1 membrane supported on commercially available porous alumina tubes was prepared by firstly dip-coating the tubes in silica colloid sol and then using a hydrothermal synthetic process.The mesoporous silicalite-1 membrane was further modified by grafting organosilane compounds with various alkyl chains length(C_nH_(2n+1)(CH_3)_2SiCl;n = 1,3,8,12 and 18).These hydrophobic silicalite-1 membranes containing silane coupling agents effectively removed ethanol from 3 wt.%,5 wt.%and 10 wt.%aqueous ethanol solutions by pervaporation over a temperature range of 303-323 K.The separation factor(a) of ethanol decreased as the ethanol content in the feed solution increased from 3%to 10%whereas the permeation flux(J) basically remained constant.Ethanol separation factors(a) of 7.90-22.24 with total fluxes(J) of 0.76-2.89 kg/(m^2h) were obtained by pervaporation at 3_3-323 K for ethanol feed composition of 3%-10%.

Enhanced CH4 yield by photocatalytic CO2 reduction using TiO2 nanotube arrays grafted with Au, Ru, and ZnPd nanoparticles

Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.

Hydrophobe-substituted bPEI derivatives: boosting transfection on primary vascular cells

Gene therapy targeted to vascular cells repre- sents a promising approach for prevention and treatment of pathological conditions such as intimal hyperplasia, in-stent and post-angioplasty restenosis. In this context, polymeric non-viral gene delivery systems are a safe alternative to viral vectors but a further improvement in efficiency and cytocom- patibility is needed to improve their clinical success. Herein, a library of 24 branched polyethylenimine （bPEI） derivatives modified with hydrophobic moieties was synthesised, char- acterised and tested in vitro on primary vascular cells, aim- ing to identify delivery agents with superior transfection effi- ciency and low cytotoxicity. Low molecular weight PEIs （0.6, 1.2 and 2 kDa） were grafted with long （C18） and short （C3） aliphatic chains, featuring different unsaturation degrees and degrees of substitution. 0.6 kDa bPEI-based derivatives were generally ineffective in transfection on vascular smooth mus- cle cells （VSMCs）, while among the other derivatives some promising vectors were identified. Forcing polyplexes on the cell surface by means of centrifugation invariably boosted transfection levels but increased cytotoxicity as well. Of note, a propionyl-snbstituted derivative （PEI2-PrA1, C3：0） was the most effective on both VSMCs and endothelial cells （ECs）, with higher and more sustained gene expression in combi- nation with markedly lower cytotoxicity with respect to the gold standard 25 kDa bPEI. In addition, a linoleoyl-substi- tuted derivative （PEI1.2-LA6, C18：2） owing to its high effi- ciency in VSMCs and relative inefficacy in ECs, combined with tolerable cytotoxicity was proposed as a vector for spe- cific VSMCs targeting.