Alcohol-assisted rapid growth of vertically aligned carbon nanotube arrays

Millimeter-to-centimeter scale vertically aligned carbon nanotube (VACNT) arrays are widely studied because of their immense potential in a range of applications. Catalyst control during chemical vapor deposition (CVD) is key to maintain the sustained growth of VACNT arrays. Herein, we achieved ultrafast growth of VACNT arrays using Fe/Al₂O₃ catalysts by ethanol-assisted two-zone CVD. One zone was set at temperatures above 850 °C to pyrolyze the carbon source and the other zone was set at 760 °C for VACNT deposition. By tuning synthesis parameters, up to 7 mm long VACNT arrays could be grown within 45 min, with a maximal growth rate of ∼280 μm/min. Our study indicates that the introduction of alcohol vapor and separation of growth zones from the carbon decomposition zone help reduce catalyst particle deactivation and accelerate the carbon source pyrolysis, leading to the promotion of VACNT array growth. We also observed that the catalyst film thickness did not significantly affect the CNT growth rate and microstructures under the conditions of our study. Additionally, the ultralong CNTs showed better processability with less structural deformation when exposed to solvent and polymer solutions. Our results demonstrate significant progress towards commercial production and application of VACNT arrays.     

Efficacy of low concentration neutralised electrolysed water and ultrasound combination for inactivating Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012 on stainless steel coupons

The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift drops: 2.2 and 3.1 log CFU/coupon reductions within 0.2 min for E. coli ATCC 25922 and P. pastoris GS115, respectively and 1.0 log CFU/coupon reductions within 0.1 min for A. pullulans 2012. Air-dried cells after treatment were studied by atomic force microscopy (AFM)/optical microscopy (OM) and protein leakage analyses further. All three strains showed visible cell damage after LCNEW and LCNEW combined with ultrasound treatment and 1.41 and 1.73 μg/mL of protein leakage were observed for E. coli ATCC 25922 and P. pastoris GS115, respectively after 3 min combination treatment, while 6.22 μg/mL of protein leakage for A. pullulans 2012 after 2 min combination treatment. For biofilms, LCNEW combined with ultrasound also significantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.     

Efficient numerical integration of an elastic–plastic damage law within a mixed velocity–pressure formulation

This study focuses on numerical integration of constitutive laws in numerical modeling of cold materials processing that involves large plastic strain together with ductile damage. A mixed velocity–pressure formulation is used to handle the incompressibility of plastic deformation. A Lemaitre damage model where dissipative phenomena are coupled is considered. Numerical aspects of the constitutive equations are addressed in detail. Three integration algorithms with different levels of coupling of damage with elastic–plastic behavior are presented and discussed in terms of accuracy and computational cost. The implicit gradient formulation with a non-local damage variable is used to regularize the localization phenomenon and thus to ensure the objectivity of numerical results for damage prediction problems. A tensile test on a plane plate specimen, where damage and plastic strain tend to localize in well-known shear bands, successfully shows both the objectivity and effectiveness of the developed approach.     

Simplified algorithm for the prediction of water sorption isotherms of fruits,vegetables and legumes based upon chemical composition

A simplified algorithm of prediction of water sorption isotherms for some foods was developed. This model is based on the composition of the main compounds of foods (glucose, fructose, sucrose, salt, protein, fibre and starch) and the influence of temperature was included (it was tested at 25 and 40 °C). Reported experimental data were employed as reference to validate the developed prediction model. Sorption isotherms for apple, apricot, banana, chestnut, loquat, quince, raisin, carrot, garlic, pepper, pumpkin, turnip, potato, bean, chickpea and lupine were predicted and compared to those reported in literature. The proposed model was able to predict the presence or absence of crossing between sorption isotherms at different temperatures for the same food. Using the prediction model could be calculated equilibrium moisture content with a determination coefficient (R²) of (>0.982), a mean relative error (E) of (<9.43%) and a standard error (E_RMS) of (<0.042 kg (kg d.b.)⁻¹).     

Preliminary study on the tribology of an organic-molecule-coated touch panel display surface

The use of touch panel displays has been increasing due to the popularity of tablet PCs and smart phones. In order to protect the touch panel surface from scratches, contaminants from fingerprints and skin oils and so on, anti-contamination coating is necessary.One of the ways to protect the surface is to cover it with a thin and dense organic molecular layer. At the present time, the primary requirement for the coating is fingerprint-resistance or easy removal of contaminants. An adsorbed molecular layer of PFPE-derivatives is currently used for this purpose, in order to reduce the surface energy of the surface. Since the current major concern of panel makers is anti-fingerprint performance, degradation of the molecular layer by both tribological and environmental conditions is a major issue for the development of the coatings.Given the current priorities, however, tribological research into such subjects as the touch feeling of the panel and the friction characteristic has not been conducted. The touch feeling and its relation to the operation are very important but very difficult to study because it is very hard to express the touch feeling numerically. As a preliminary study, several different coated surfaces were prepared and their friction coefficients were measured by rubbing with a finger or a steel or glass ball to clarify the tribological characteristics of the surface.An Si wafer and a glass plate were used in this study as models of the solid substrate of a display. They were coated with an adsorbed organic molecular layer of two PFPE-derivatives with different molecular structures named Type-F and Type-D or several reference molecular layers, such as OTS-SAM and FDTE-SAM. In addition to the tribological data, degradation by UV irradiation was also examined to compare the performance. The results are discussed from the tribological and chemical points of view.     

基于FPGA的DDS信号源设计

介绍了DDS(直接数字合成)信号源的原理及组成,给出了VHDL(甚高速集成电路硬件描述语言)源代码,并探讨了在设计中应注意的事项。文中介绍的设计方法和代码已经过实验验证。采用VHDL在FPGA(现场可编程门阵列)器件上完成数字系统的设计,可以大大简化设计过程,提高设计效率,并可以根据实际要求进行灵活修改,充分显示了EDA(电子设计自动化)技术的特点与优势。     

3D 游戏中“刀光剑影”特效的实现算法

＂拖影＂,就是指3D游戏中,冷兵器在舞动时所＂拖＂出的光影。分析了＂拖影＂特效的图形变化规律,提出了一种实用的＂拖影＂特效实现算法。借助该算法,应用程序可以根据兵器的运动轨迹,自动产生＂拖影＂效果。最后,还结合实际应用的经验,对算法进行了改进。这种算法已成功应用于多款3D游戏,并很好地与各种程序引擎相结合。     

Synthesis and performance of three flame retardant additives containing diethyl phosphite/phenyl phosphonic moieties

Three novel intumescent flame retardants (IFRs) containing phosphorus and nitrogen based on Schiff bases, poly(phosphonate ester(s)) (designated as PAB, PEB, and PPB), were synthesized and characterized. Thermal stability and flammability properties of ethylene-vinyl acetate copolymer (EVA)/30% IFRs blends were investigated by thermogravimetric analysis (TGA), limited oxygen index (LOI), vertical burning test (UL-94) and microscale combustion calorimetry (MCC). The results from UL-94 showed that EVA/IFRs blends all could reach V-2 rating. The addition of PAB into EVA reduced the PHRR value by 31%, and the LOI value increased from 19 to 24. Scanning electron microscope (SEM) observation results indicated that the existence of the cohesive charred layer on the surface of the residue was responsible for the improvement of the flame retardancy of EVA.