Changes of the cell surface hydrophobicity of Lactobacillus acidophilus La‐5 in response to pH,temperature and inulin

The main topic of this study was to study how cell surface hydrophobicity (CSH) could change in response to pH, temperature and inulin; Lactobacillus acidophilus La‐5 was used as a model microorganism. pH, temperature, inulin and incubation time (exposure to prebiotic or incubation at pH 4.0 and 9.0) were combined through a full factorial design and a Central Composite Design; the results were analysed using a multifactorial anova (first step) and a stepwise regression (second step). Temperature and pH significantly affected CSH: an increase in the temperature determined a significant increase in CSH, whereas the correlation pH vs. CSH was negative, as an increase in pH caused a significant decrease in CSH. Inulin played a significant role, but its effect could be influenced by temperature, pH and exposure time. This study is the first approach on the effects of some environmental factors on CSH and suggests that the culturing conditions and/or the exposure to some prebiotics could modify it with positive or negative effects.     

试验设计技术在确定汽车收音机最大产热的设置条件中的应用

阐述了如何确定汽车收音机在什么设置条件下产生的热量最大的方法。主要采用L8DoE(Design of Exper Jments)方法，确定设置条件后选择合适的DoE因素，可预测汽车音响出现产热的最坏情况的设置条件以及在此设置条件下的热量值。该方法同样可应用于其它多媒体组件的热量特性试验。     

Formable chromium nitride coatings for proton exchange membrane fuel cell stainless steel bipolar plates

Among the different coatings developed for proton exchange membrane fuel cell steel bipolar plate, nitride-based coatings present several advantages compared to gold or polymeric coating: high chemical stability, low interfacial contact resistance and reasonable cost. In this work, 50 nm thick chromium nitride coatings are deposited by reactive magnetron sputtering on 316L stainless steel foil. They are optimized to fulfill the Department of Energy targets in terms of interfacial contact resistance (ICR) and corrosion resistance, with values of 8.4 mΩ cm⁻² (at 100 N cm⁻²) and 0.10 μA cm⁻² (in 0.6 M H₂SO₄ solution at 0.48 V_vs. SCE potential) respectively. Moreover, they retain their excellent properties after high deformation (biaxial deformation of 20% in x-axis and 5% in y-axis), giving the possibility to achieve, in line, the stamping of a bipolar plate from a coated foil. The etching of the substrate, prior to the coating deposition, appears to be determinant to obtain low and stable corrosion current and ICR. The removing of interfacial oxyde leads to better coating adhesion and improves the corrosion resistance and electrical conductivity. The enhancement of the properties (low ICR and high corrosion resistance) is durable, with no signicant change of the ICR value up to 200 days after deposition.     

Solidification of hesperidin nanosuspension by spray drying optimized by design of experiment (DoE)

Objective: To accelerate the determination of optimal spray drying parameters, a “Design of Experiment” (DoE) software was applied to produce well redispersible hesperidin nanocrystals.

Significance: For final solid dosage forms, aqueous liquid nanosuspensions need to be solidified, whereas spray drying is a large-scale cost-effective industrial process.

Methods: A nanosuspension with 18% (w/w) of hesperidin stabilized by 1% (w/w) of poloxamer 188 was produced by wet bead milling. The sizes of original and redispersed spray-dried nanosuspensions were determined by laser diffractometry (LD) and photon correlation spectroscopy (PCS) and used as effect parameters. In addition, light microscopy was performed to judge the redispersion quality.

Results: After a two-step design of MODDE 9, screening model and response surface model (RSM), the inlet temperature of spray dryer and the concentration of protectant (polyvinylpyrrolidone, PVP K25) were identified as the most important factors affecting the redispersion of nanocrystals. As predicted in the RSM modeling, when 5% (w/w) of PVP K25 was added in an 18% (w/w) of hesperidin nanosuspension, subsequently spray-dried at an inlet temperature of 100?°C, well redispersed solid nanocrystals with an average particle size of 276?nm were obtained. By the use of PVP K25, the saturation solubility of the redispersed nanocrystals in water was improved to 86.81?µg/ml, about 2.5-fold of the original nanosuspension. In addition, the dissolution velocity was accelerated.

Conclusions: This was attributed to the additional effects of steric stabilization on the nanocrystals and solubilization by the PVP polymer from spray drying.     

Optimization of photochemical machining process parameters for manufacturing microfluidic channel

In the present study, the investigation on photochemical machining (PCM) of stainless steel (SS-304) by ferric chloride as etchant is reported. SS-304 is machined by PCM process to obtain accurate dimensions and better geometrical features. Weighted grey relational analysis (WGRA) technique is used in optimization of PCM process parameters. DoE (L₂₇) orthogonal array is applied to evaluate machining parameters, such as concentration of etchant, etching time, and temperature of etchant. The multiobjective optimization technique is used to optimize material removal rate (MRR), surface roughness (R_a), undercut (U_c) and etch factor (EF). Weighted grey relational grade is calculated to minimize U_c and surface roughness and to maximize MRR and EF. The quality characteristics MRR, EF, U_c, and R_a are reporting the improvement after the confirmatory test. The optimum machining parameters are processed to manufacture the microfluidic channel used in biomedical applications. The microfluidic channels and its assembly with Y-type for mixing of fluid with a size of 100 µm, 200 µm, and 300 µm are developed and investigated.     

Development of a dosing strategy for a heavy-duty diesel exhaust cleaning system based on NOX storage and reduction technology by Design of Experiments

A dosing strategy for the transient control of an exhaust after-treatment system using the NO_X storage and reduction approach was developed on a heavy-duty diesel engine rig equipped with an 11 l diesel engine. The catalysts were oxidation catalysts of 8.4 l and NO_X storage and reduction catalysts of 16.8 l total volume. The dosing strategy has been tested in a European Transient Cycle (ETC) resulting in a NO_X reduction of 60% (by 4.5 g/kWh) with a fuel penalty of 6.6% when the catalysts were preconditioned to 450 °C. The reducing agent was diesel fuel. To keep the fuel penalty low, a bypass system was used which bypassed approximately 90% of the exhaust flow under the regeneration periods. The parameters for the dosing strategy were obtained from steady-state optimization experiments (constant speed and torque) using Design of Experiments (DoE) to obtain much information from few experiments. The system was optimized for a high degree of NO_X reduction with a low fuel penalty. The period when the flow through the catalyst is reduced (bypass time), the cycle time, the injection time and rate are important parameters to achieve an improved NO_X reduction. The optimal values of these parameters varied with the load points used. The steady-state NO_X conversion was approximately 60% (3.3–4.1 g/kWh) at catalyst temperatures between 330 and 530 °C. The most promising parameters for a large NO_X reduction and a low fuel penalty have been applied in the dosing strategy and tested in an ETC.     

Effects of different sealing conditions on the seal strength of polypropylene films coated with a bio‐based thin layer

This paper presents the results of an investigation through the design of experiment technique regarding the influence of temperature, dwell time and bar pressure on the heat seal strength of oriented polypropylene films coated with a gelatin‐based thin layer. This chemometric approach allowed achieving a thorough understanding of the effect of each independent factor on the two different responses (maximum force and strain energy) considered in this work as a measure of the strength necessary to break the bond across the sealed interface. Surprisingly, the factor affecting both responses the most was the bar pressure rather than the sealing temperature. Moreover, whereas the bar pressure negatively affected the seal strength of coated polypropylene films, the sealing temperature had a positive effect. Dwell time did not have any significant influence as a main factor, while influencing negatively the seal strength as an interaction term (i.e. time × pressure), together with the further interaction temperature × pressure. The mathematical models obtained for the two responses provided different results in terms of fitting capability (R²) and prediction ability (Q²). In particular, for the maximum force response, R² and Q² were equal to 0.571 and 0.405, respectively, whereas the model supporting the strain energy response gave R² = 0.932 and Q² = 0.937, highlighting that for quantifying the seal strength, the energy necessary to break a seal is a better measure than the maximum force. The highest seal strength values obtained during this work were of 0.6615 N and 19.6 N·mm for maximum force and strain energy, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimizing dimensional accuracy of titanium alloy features produced by wire electrical discharge machining

This study investigates geometrical errors such as cylindricity, circularity and diametral errors of a feature (a hole) produced from wire electrical discharge machining of Ti6Al4V alloy where tension in wire, pulse on time, and flushing pressure are varied. Pareto analysis of variance (ANOVA), Taguchi design of experiment (DoE), and traditional analysis estimate the influence of variables on errors of holes. It was noted that flushing pressure is the most significant factor with individual contributions of 31.02%, 49.5% and 37.84% to circularity, cylindricity, and diametral errors, respectively. The circularity error of holes decreases as the flushing pressure and tension in wire rise, but decreases with the rise of pulse on time. The cylindricity error decreased with the increase of wire tension, flushing pressure and pulse on time. The absolute diametral error reduced as the pulse on time and tension in wire raised, but it raised with the rise of pulse on time. All these trends are associated with the influence of tension in wire on the flexibility of wire, the dependence of heat generation and dissipation on pulse on time, and ability of the flushing pressure to control the cooling, as well as debris removal from the machining zone.     

Optioneering: A New Basis for Engagement Between Architects and Their Collaborators

Conventionally, architects are somewhat tardy when inviting engineers to join their projects. By only introducing consulting engineers to participate in the later stages of the design process, engineers are commonly assigned a fixing role. This provides little opportunity for creative engineering solutions at the generative stage. Optioneering, a new business management model, however, offers the possibility of a new collaborative method for interaction between designers and their partners. Dominik Holzer and Steven Downing describe how a research project between the Spatial Information Research Laboratory (SIAL) at the Royal Melbourne Institute of Technology (RMIT) and the engineering firm Arup investigated the capability of this new form of collaboration. Copyright © 2010 John Wiley & Sons, Ltd.