Hybrid polymeric scaffolds prepared by micro and macro approaches

Polymeric scaffolds with complex porous structures were fabricated with two different polymers by combining three fabrication methods in three steps, in which, nonwoven poly(ε-caprolactone) microfibers were obtained with electrospinning and immersed in solvent cast chitosan solution poured in Petri dish to fabricate hybrid polymers, and finally the combined structure was freeze-dried with two different predrying techniques to obtain macropores in the structure. The resulting hybrid polymeric mats were found to have both microfibers and macroporosity due to the electrospinning as well as freeze-drying processes, which resemble the natural extracellular matrix. The optimized scaffolds that predried in the incubator at 40°C for 5?h and then freeze-dried for 24?h exhibited contact angle value of 68.93?±?2.18° with 3.252?±?0.783?MPa Young’s modulus and 0.260?±?0.002?MPa yield strength as well as 1.35-fold cell yield in MRC5 fibroblast cell culture, compared to the commercial tissue culture polystyrene.     

Virtual reality in requirement analysis for CIM system development suitable for SMEs

This paper presents a methodology, based on Virtual Reality (VR), for representing a manufacturing system in order to help with the requirement analysis (RA) in CIM system development, suitable for SMEs. The methodology can reduce the costs and the time involved at this stage by producing precise and accurate plans, specification requirements, and a design for CIM information systems. These are essentials for small and medium scale manufacturing enterprises. Virtual Reality is computer-based and has better visualization effects for representing manufacturing systems than any other graphical user interface, and this helps users to collect information and decision needs quickly and correctly. A VR-RA tool is designed and developed as a software system to realize the features outlined in each phase of the methodology. A set of rules and a knowledge base is appended to the methodology to remove any inconsistency that could arise between the material and the information flows during the requirement analysis. A novel environment for matching the physical and the information model domains is suggested to delineate the requirements.     

Estimating the Effect of Helium and Nitrogen Mixing on Deposition Efficiency in Cold Spray

Cold spray is a developing technology that is increasingly finding applications for coating of similar and dissimilar metals, repairing geometric tolerance defects to extend expensive part life and additive manufacturing across a variety of industries. Expensive helium is used to accelerate the particles to higher velocities in order to achieve the highest deposit strengths and to spray hard-to-deposit materials. Minimal information is available in the literature studying the effects of He-N₂ mixing on coating deposition efficiency, and how He can potentially be conserved by gas mixing. In this study, a one-dimensional simulation method is presented for estimating the deposition efficiency of aluminum coatings, where He-N₂ mixture ratios are varied. The simulation estimations are experimentally validated through velocity measurements and single particle impact tests for Al6061.     

Ozone applications for after‐clearing of disperse‐dyed poly(lactic acid) fibres

In this study, the effectiveness of the ozonation process, in neutral distilled water at room temperature, as a clearing process for disperse‐dyed poly(lactic acid) fibre fabrics is investigated. The efficiency of simultaneous decolorisation of dyebath effluent and clearing of dyed poly(lactic acid) in the cooled dyebath after completion of the poly(lactic acid) dyeing cycle is also explored. Conventional alkaline reduction clearing with sodium dithionite was chosen as a control clearing process for comparison. Wash fastness, colour difference, colour removal (in Hazen) and chemical oxygen demand values were determined and compared. Long ozone treatment times at high ozone dose resulted in unacceptable colour differences. The colour difference problem was solved by use of lower ozone dose; however, a warm soaping step had to be added to the after‐clearing sequence in order to achieve the desired fastness properties. A 33% reduction on the chemical oxygen demand load of the total process (dyeing + after‐clearing) could be achieved by ozone after‐clearing instead of using a conventional reduction clearing treatment. The addition of the warm soaping step to improve the fastness properties of the ozonated samples increased the total chemical oxygen demand of the process (dyeing + ozonation in water + warm soaping), but a 12–18% reduction on the chemical oxygen demand load of the total process was observed when compared with the conventional treatment sequence (dyeing + reduction clearing).     

The effect of hydrogen shielding gas on microstructure and abrasive wear behavior in the surface modification process using the tungsten inert gas method

In this study, SAE 1020 steel surfaces were separately alloyed with preplaced high-carbon ferro-chromium (FeCr), ferro-molybdenum (FeMo), and ferro-titanium (FeTi) powders by using a tungsten inert gas (TIG) heat source. By using two different types of shielding gas compositions during the alloying process, the study investigated the effects of modified shielding gas composition on the microstructure, hardness, and abrasive wear resistance of specimens. It was observed that with modifications in shielding gas composition, the microstructure and volume hardness of the specimens changed and no cracks and voids were formed in the interface area. The X-ray examinations of the specimens identified Fe, FeTi, and FeMo phases in their microstructure as the first phase, and Cr₇C₃, Fe₃C, Fe₇C₃, and TiC phases as the second phase. As a result, it was concluded that changes in shielding gas composition in surface alloying process significantly affect specimens’ microstructure and mechanical properties.     

聚乳酸（Ingeo）染色织物碱性还原清洗工艺研究

研究了不同碱性还原清洗工艺对聚乳酸分散染料染色织物的作用效果。结果表明，聚乳酸色织物在碳酸钠2g／L，连二亚硫酸钠2g／L，温度60℃，时间15min的还原清洗工艺条件下效果最佳，不仅织物的色深值没有明显的降低，而且水洗牢度也达到了最佳值。     

Highly Extensible Bio‐Nanocomposite Films with Direction‐Dependent Properties

The structure and mechanical properties of bio‐nanocomposite films made from poly(ethylene oxide) (PEO) that is physically cross‐linked with silicate nanoparticles, Laponite, are investigated. Direction‐dependent mechanical properties of the films are presented, and the effect of shear orientation during sample preparation on tensile strength and elongation is assessed. Repeated mechanical deformation results in highly extensible materials with preferred orientation and structuring at the nano‐ and micrometer scales. Additionally, in vitro biocompatibility data are reported, and NIH 3T3 fibroblasts are observed to readily adhere and proliferate on silicate cross‐linked PEO while maintaining high cell viability.     

Lipid components of flax,perilla, and chia seeds

Composition of fatty acids, tocopherols, sterols, and TAGs in the lipids of flax, perilla, and chia seeds were investigated where lipid content was at 45, 40, and 35%, respectively. α‐Linolenic acid (ALA) dominated among fatty acids in all oils and accounted for 58.2, 60.9, and 59.8% in flax, perilla, and chia, correspondingly in these three oils trilinolenin was the main TAG found at 19.7, 22.6, and 21.3%. Triunsaturated TAGs accounted for 77.9, 77.5, and 74.5% of the total amounts in flax, perilla, and chia oils. Contents of tocopherol were at 747 in flax, 734 in perilla, and 446 mg/kg in chia seed lipids. γ‐Tocopherol was the dominating isomer contributing 72.7% in flax, 94.3% in perilla, and 94.4% in chia to the total amount of tocopherols. Flaxseed lipids contained 25.6% of plastochromanol‐8, derivative of γ‐tocotrienol with longer side chain; perilla and chia oils contained only 1.4% of it. Phytosterols were present at 4072, 4606, and 4132 mg/kg in those seeds, respectively. Among sterols, β‐sitosterol dominated and was found at 35.6, 73.3, and 49.8% of the total amounts of sterols in flax, perilla, and chia seed lipids. All of the investigated oilseeds have an excellent nutritional quality and can be a potential source of nutraceutical fats which can enrich diet in linolenic acid and other functional components.     

Design of complex flow line system by simulation

During the last two decades or so, there have been several attempts to gain insights into the operational behaviour of mechanical and manual flow lines. However, an area which has received very little attention is the area of manual flow lines with more than one type of product input with constant or variable processing times. Such lines are more complex because each product entering into the system has a different work content which causes an uneven work flow and consequent station idle time and/or congestion of semi-finished products.In this paper, a flow line with mixed product supply which is deterministicin the number of arriving units and probabilistic in the structure of the product mix is considered. No buffer stocks between service stations are provided; queue formation of limited length is allowed; the stations are located in series on the line, and each station is allowed to use multiple servers working in parallel. The service times are assumed to be normally distributed with known mean times and variances. The objective is to design a flow line system which would provide an even flow of work where over or under utilization of servers is avoided. This is achieved by increasing or decreasing the number of service stationsby several simulations until a utilization level is achieved which is feasable for the management.GERTS III Q network modeling and simulation technique is used for the solution of the design problem. This technique leads effectively to the achievement of the objective set forth for the solution of the problem.