Influence Of Fabrication Parameters Research Articles

Biodegradable Polymeric Microcarriers with Controllable Porous Structure for Tissue Engineering

Porous microspheres fabricated by biodegradable polymers show great potential as microcarriers for cell cultivation in tissue engineering. Herein biodegradable poly(DL-lactide) (PLA) was used to fabricate porous microspheres through a modified double emulsion solvent evaporation method. The influence of fabrication parameters, such as the stirring speed of the primary and secondary emulsion, the polymer concentration of the oil phase, and solvent type, as well as the post-hydrolysis treatment of the porous structure of the PLA microspheres are discussed. Good attachment and an active spread of MG-63 cells on the microspheres is observed, which indicates that the PLA microspheres with controllable porous structure are of great potential as cell delivery carriers for tissue engineering.

Thermoelectric micro converters for cooling and energy-scavenging systems

This paper describes the fabrication process of thermoelectric microconverters, based on n-type bismuth telluride (Bi2Te3) and p-type antimony telluride (Sb2Te3) thin films. The films are fabricated by thermal co-evaporation with thermoelectric properties comparable to those reported for the same materials in bulk form (used in conventional macro-scale Peltier modules). The absolute value of the Seebeck coefficient in the range of 150–250 µV K−1 and an in-plane electrical resistivity of 7–15 µΩ m were obtained. The influence of fabrication parameters on thermoelectric properties is reported. The films were patterned by photolithography and wet-etching techniques, using HNO3/HCl-based etchants. The influence of composition and concentration of etchants in the lithographic process is reported. A microcooler was fabricated.

Research on the influence of fabrication parameters on the performance of buried ion-exchanged glass waveguides using the variational method

The variational method is proposed to analyze the influence of the fabrication parameters on the performance of buried K+-Na+ ion-exchanged Er3+-Yb3+ ions co-doped glass waveguide. The unknown parameters of the Hermite-Gaussian functions as the trial field distribution are determined based on the scalar variational principle. It is demonstrated that the results calculated in this paper agree with those measured in the experiment. The mode dimensions, the effective refractive index, and the overlap factor as the functions of the fabrication parameters are investigated. These results of the variational analysis are useful for the design and optimization of Er3+-Yb3+ ions co-doped waveguides.

Fabrication of Carbon Aerogels

RF (Resorcinol-Formaldehyde) aerogels and carbon aerogels were prepared through the sol-gel method following the routes of polymerization, gelation, supercritical drying and pyrolysis processes. The influence of fabrication parameters on the textural structure of the samples, e.g., specific surface area, pore size, and pore size distribution, etc., were systematically investigated. With a decrease in the R/F molar ratio, or an increase in the catalyst content within a limited range, the porosity of the nanostructure materials increases. The optimal temperature of pyrolysis for RF aerogel was investigated by TGA (Thermogravimetric Analysis).

Relationship Between Dip-Coating Fabrication Parameters and the Elastic Properties of Rubber Latex Prosthesis

AbstractIn the present work we are mainly interested in the use of the natural latex extract from the Hevea brasiliensis for medical applications. This presentation focuses on the influence of the fabrication parameters on the final elastic properties of the tubes obtained by dip-coating. The elastic properties of the prosthesis were investigated using tension-deformation experiments. The influence of important fabrication parameters were studied, such as: dip-coating velocity, final prosthesis thickness (which was varied as a function of the number of baths), and thermal treatment. Single and cycled tension-deformation experiments were performed with closed and opened samples considering longitudinal and axial directions. A model is proposed for the anisotropy of the elastic behavior, which involves the sulfur bonds between polymeric chains.

Evaluation of mock-ups before manufacture of a shield block prototype by powder HIP

Hot isostatic pressing (HIP) of powder is proposed as a possible process for manufacturing primary wall blanket modules for the International Thermonuclear Experimental Reactor (ITER). The method is cost-effective and offers very good design flexibility. It also provides required, uniform material properties, and the material is easy to check with ultrasonic techniques. Bodycote Powdermet conducted a development programme as a part of a NET (Next European Torus) contract to manufacture a shield block for the ITER primary wall module prototype. The aim was to test the influence of geometry of the tube gallery on the tolerances of tube positions after HIP of one-eighth scale (724×318×299 mm 3) prototype mock-ups. It also intended to verify results obtained earlier on the influence of fabrication parameters. Five mock-ups were produced. Four HIP cycles were tested using two different designs of the cooling galleries. Non-destructive testing was used and measurements on sections of the mock-ups were performed. The location of tubes facing the first wall is most important. Investigation showed very small differences between the locations of those tubes in the five mock-ups. For these mock-ups, the tolerances between the surface and the tubes could be kept within ±2 mm.

The influence of fabrication parameters on the deformation behaviour of the preform of metal-matrix composites during the squeeze-casting processes

Through a series of experiments with preforms that had a randomly-oriented fiber distribution, the deformation of the preform and the tensile strength of the metal-matrix composites were investigated with variation of processing parameters such as the punch velocity, the amount of binder, the preform temperature, the fiber volume fraction and the applied pressure. Experimental data are presented on the injection of aluminum-alloy melts into preforms composed of δ-alumina short fibers with a silica binder. The preforms were prepared from liquid slurry using the vacuum filtration process. The base material used in this study was A12024, having poor fluidity compared with a casting aluminum alloy. Scanning electron and optical micrographs are also presented for investigating the effects of processing parameters on the microstructures of the metal-matrix composites. Recommendations are put forward concerning the optimization of the microstructure through control of the processing parameters.

Test Method for Cloth Fell Displacement Caused by Relaxation

A test method is presented for measuring cloth fell displacement during relaxation of fabric yarn combinations on a tensile tester. The equipment consists of a CCD camera, a frame grabber, and appropriate software. The method is used to analyze the cloth fell displacement of twenty different fabrics. The influence of fabric parameters is determined using statistical techniques.

Influence of imperfections on the strength of unstiffened, fabricated, tubular beam-columns

Abstract Fabricated tubular steel members are used in offshore structures as primary and secondary members; typical applications in fixed structures incorporate large diameter tubes in truss-type assemblies. These unstiffened tubes are formed by rolling plate into cylindrical components which are then seam and girth welded to create the circular tubular shape. The members produced in this fashion have characteristic imperfections which are different from those found in smaller diameter seamed or seamless hollow structural and pipe sections. These imperfections and their influence on the structural behaviour of beam-columns are subject of the study and results presented here. Earlier experimental studies at the University of Toronto on the influence of fabrication parameters are the foundation of the results reported here. Extensive measurements of as-fabricated geometry provided information on actual shape and these measured geometries are used to establish the analytical models using a finite element program, ANSYS; this program permits the modelling of non-linear material and geometric effects. The ultimate and post-ultimate local buckling behaviour was studied in the analyses to the same extent as observed in experiments. The load-displacement behaviour of tubular members depends significantly on the tube geometry and material properties. The discretization of the tube into elements is shown to require careful consideration so that potential deformation modes are not missed. Bilinear kinematic hardening material based on coupon tests of the ‘as fabricated’ steel, in combination with geometric modelling techniques yielded a behaviour response with a close resemblance to the experimental observations and measurements. The relative importance of various parameters is discussed and direct comparisons of experimental and analytical results with current code resistance formulations are made. The specific effects of residual strains are not addressed in this paper.

Elastic Behavior of Woven Hybrid Composites

Basic geometrical and material parameters are identified to characterize the structure of hybrid fabrics. Analysis of the elastic behavior is made based upon a mosaic model and the fabric composite can be regarded as an assemblage of assymetrical crossply laminates. Upper and lower bounds of elastic properties have been obtained and the results compare very favorably with experiments. The influence of fabric parameters on the elastic behavior has been demonstrated especially for the bending-stretching coupling effect. Essential considerations for fabric design also have been discussed.