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Mold
Kinds of Mold Terms modified by Mold Selected AbstractsCONTAMINATION OF GRAINS BY MYCOTOXIN-PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATIONJOURNAL OF FOOD SAFETY, Issue 3 2006NAGY H. AZIZ ABSTRACT Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B1 ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0-kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage. [source] ISOLATION AND CHARACTERIZATION OF BACTERIOCIN-PRODUCING MICROORGANISMS FROM AGOS-OSJOURNAL OF FOOD SAFETY, Issue 3 2000JULIE D. TAN ABSTRACT Agos-os, a fermented meat and sweetpotato mixture, was produced and analyzed for its microbial characteristics. pH decreased during fermentation. Mold and anaerobic bacterial counts increased while yeasts and aerobic bacterial counts decreased during the third and seventh day of fermentation. Six isolates with the widest zones of inhibition on the indicator lawn were selected for bacteriocin production. These isolates had exactly the same morphological, physiological and biochemical characteristics. The ribosomal RNA sequence was 99.5% identical with Enterococcus faecalis VRE 1492. The identification was confirmed through DNA homology test by the EMBL Genbank, Canada. This bacterium produced the L-isomer lactic acid. The amount of bacteriocin produced by the bacterium was optimized by growing the bacterium at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was achieved in MRS (De Man Rugosa and Sharpe) medium (with glucose) at pH 7.50. The crude bacteriocin inhibited the growth of gram-positive bacteria such as Lactobacillus sake 15521 and Listeria innocua. The gram-negative bacteria such as Escherichia coli DH 5-alpha (with plasmid, PUC), Salmonella typhii and Staphylococcus aureus were weakly inhibited. Other microorganisms such as Lactobacillus curvatus D31685, Lactobacillus confusius M23036, Lactococcus lactis MG1363, Leuconostoc paramesenteroides S67831, Pediococcus pentosaceus M58834, Saccharomyces cerevisiae SS553 (wild type) and Escherichia coli JM109 (no plasmid) were not inhibited. [source] Selection and Use of Postharvest Technologies as a Component of the Food ChainJOURNAL OF FOOD SCIENCE, Issue 2 2004MALCOLM C. BOURNE ABSTRACT: Postharvest technologies refer to the stabilization and storage of unprocessed or minimally processed foods from the time of harvest until final preparation for human consumption. There is a special emphasis on seasonal crops, and simple, labor-intensive, capital-sparing technologies suitable for developing countries where food spoilage rates are high and malnutrition is prevalent. The first step is to determine the major spoilage vectors for each type of food and then identify a technology that will control that vector. For cereal grains the major spoilage vectors are mold, insects, rodents, and other vertebrate pests. Mold is controlled by prompt and adequate drying to a water activity below 0.7. Insects are controlled by good housekeeping, and use of insecticides and fumigants. Rodents are controlled by baits, traps, fumigants, and rodent-proof storage structures. For fruits, vegetables, roots, and tubers the main spoilage vectors are bruising, rotting, senescence, and wilting. Bruising is avoided by careful handling and use of shock-resistant packaging. Rotting is controlled by good housekeeping, gentle handling to avoid breaking the skin, cool storage, and use of preservatives. Senescence is retarded by cold storage or controlled-atmosphere storage. Wilting is controlled by high humidity and cold storage. Growth of microbes is the major spoilage of fish and other foods of animal origin. This is controlled by refrigerated or frozen storage, drying, freezing, or canning. Most spoilage vectors accelerate as the temperature and humidity increase; this makes it more difficult to control spoilage in tropical than in temperate regions. [source] Breaking the Mold of Contemporary Working-Class Mexican Masculinity: The Rock Urbano Music of Tex TexJOURNAL OF POPULAR MUSIC STUDIES, Issue 1 2008Mark A. Hernández [source] Micromolding of a Highly Fluorescent Reticular Coordination Polymer: Solvent-Mediated Reconfigurable Polymerization in a Soft Lithographic Mold,ANGEWANDTE CHEMIE, Issue 22 2010Youngmin You Dr. Fluoreszierende Streifen: Koordinationspolymere aus Zink- oder Silberionen und Pyridinderivaten als Liganden wurden auf kontrollierte Weise in Mikroschablonen erhalten, die zuvor lithographisch in Kapillaren erzeugt wurden. Dabei resultieren stark fluoreszierende Polymermuster mit supramolekularer Struktur (siehe Bild). [source] Fabrication of Ordered Nanostructured Arrays Using Poly(dimethylsiloxane) Replica Molds Based on Three-Dimensional Colloidal CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Hong Kyoon Choi Abstract Hexagonally arrayed structures of colloidal crystals with uniform surface are a good candidate for master molds to be used in soft lithography. Here, the fabrication of periodically arrayed nanostructures using poly(dimethylsiloxane) (PDMS) molds based on three-dimensionally (3D) ordered colloidal crystals is reported. A robust, high-quality 3D colloidal-crystal master molds is prepared using the colloidal suspension containing a water-soluble polymer. The surface patterns of the 3D colloidal crystals can then be transferred onto a polymer film via soft lithography, by means of the replication of the surface pattern with PDMS. Various hexagonally arrayed nanostructure patterns can be fabricated, including close-packed and non-close-packed 2D arrays and honeycomb structures by the structural modification of the 3D colloidal-crystal templates. The replicated hexagonally arrayed structures can also be used as templates for producing colloidal crystals with 2D superlattices. [source] Low-Cost Fabrication of Transparent Hard Replica Molds for Imprinting LithographyADVANCED MATERIALS, Issue 40 2009Joohee Kim A new and cost-effective replica fabrication method for transparent and hard molds used in imprinting lithography is presented. The process uses a polymer copy as a carrier. Replicated hard molds eliminate the need for direct contact between the master and the patterned polymer on the substrate, and thus reduce contamination of the master. [source] Antiadhesion Surface Treatments of Molds for High-Resolution Unconventional Lithography,ADVANCED MATERIALS, Issue 23 2006J. Lee A new strategy to achieve antiadhesion surface coatings is introduced. The approach, which uses molds coated in a thin film of poly(dimethylsiloxane) (PDMS, see figure) to achieve the antiadhesive surfaces, is applicable to virtually any type of mold material due to the use of silane chemistry and the low surface energy of PDMS. This allows simple and rapid replication of high complexity, high-aspect-ratio nanostructures with excellent replication fidelity. [source] Elastomeric Molds with Tunable Microtopography,ADVANCED MATERIALS, Issue 23-24 2004M. Hoffman Elastomeric "microtunable" molds (,TMs) whose microtopography can be tuned post-fabrication at certain pre-defined locations have been devised. Their features make them very attractive for the molding of complex microstructures. The Figure shows a scanning electron microscopy image of poly(dimethylsiloxane) double- replicas of a ,TM whose membrane contains a 1.18,mm spiral. [source] Lost Mold Rapid Infiltration Forming of Mesoscale Ceramics: Part 1, FabricationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2009Nicholas E. Antolino Free-standing mesoscale (340 ,m × 30 ,m × 20 ,m) bend bars with an aspect ratio over 15:1 and an edge resolution as fine as a single grain diameter (,400 nm) have been fabricated in large numbers on refractory ceramic substrates by combining a novel powder processing approach with photoresist molds and an innovative lost-mold thermal process. The colloid and interfacial chemistry of the nanoscale zirconia particulates has been modeled and used to prepare highly concentrated suspensions. Engineering solutions to challenges in mold fabrication and casting have yielded free-standing, crack-free parts. Molds are fabricated using high-aspect-ratio photoresist on ceramic substrates. Green parts are formed using a rapid infiltration method that exploits the shear thinning behavior of the highly concentrated ceramic suspension in combination with gelcasting. The mold is thermally decomposed and the parts are sintered in place on the ceramic substrate. Chemically aided attrition milling disperses and concentrates the as-received 3Y-TZP powder to produce a dense, fine-grained sintered microstructure. Initial three-point bend strength data are comparable to that of conventional zirconia; however, geometric irregularities (e.g., trapezoidal cross sections) are present in this first generation and are discussed with respect to the distribution of bend strength. [source] Manufacturing Silicon Carbide Microrotors by Reactive Hot Isostatic Pressing within Micromachined Silicon MoldsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Jing-Feng Li A novel ceramic microfabrication process,based on the idea of silicon carbide (SiC) reaction sintering within a micromachined silicon mold,has been developed to produce a SiC microroter for miniaturized gas turbines. The new process involves the micromachining of silicon molds; filling the molds with powder mixtures of ,-SiC, graphite, and phenol resin; bonding the molds with an adhesive; reaction sintering by hot isostatic pressing (HIP); and the releasing of a reaction-sintered workpiece from the mold by wet etching. Using this process, we have successfully fabricated SiC microrotors with a diameter of 5 mm, whose complicated geometry was well transferred from the negative shape of the micromachined silicon mold. The reaction-HIPed SiC ceramics within Si molds showed reasonably good mechanical properties, which are comparable to those of the commercialized reaction-sintered SiC ceramics. [source] A polymeric master replication technology for mass fabrication of poly(dimethylsiloxane) microfluidic devicesELECTROPHORESIS, Issue 9 2005Hai-Fang Li Abstract A protocol of producing multiple polymeric masters from an original glass master mold has been developed, which enables the production of multiple poly(dimethylsiloxane) (PDMS)-based microfluidic devices in a low-cost and efficient manner. Standard wet-etching techniques were used to fabricate an original glass master with negative features, from which more than 50 polymethylmethacrylate (PMMA) positive replica masters were rapidly created using the thermal printing technique. The time to replicate each PMMA master was as short as 20 min. The PMMA replica masters have excellent structural features and could be used to cast PDMS devices for many times. An integration geometry designed for laser-induced fluorescence (LIF) detection, which contains normal deep microfluidic channels and a much deeper optical fiber channel, was successfully transferred into PDMS devices. The positive relief on seven PMMA replica masters is replicated with regard to the negative original glass master, with a depth average variation of 0.89% for 26 ,m deep microfluidic channels and 1.16% for the 90 ,m deep fiber channel. The imprinted positive relief in PMMA from master-to-master is reproducible with relative standard deviations (RSDs) of 1.06% for the maximum width and 0.46% for depth in terms of the separation channel. The PDMS devices fabricated from the PMMA replica masters were characterized and applied to the separation of a fluorescein isothiocyanate (FITC)-labeled epinephrine sample. [source] A New Way to Improve Glass-Forming Ability by Controlling the Preparation Conditions of Bulk Metallic GlassADVANCED ENGINEERING MATERIALS, Issue 3 2010Jie Mao Abstract The effects of mold preheating temperature on the glass-forming ability of Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys are investigated using traditional copper mold casting. It is found that there exists an optimum mold temperature for glass-forming alloy systems. For the two Zr-based alloy systems studied the optimum mold temperature is 353,K. This is explained from the perspectives of heat transfer efficiency and the wettability between liquid alloy and copper mold. [source] Identification of substrates for transglutaminase in Physarum polycephalum, an acellular slime mold, upon cellular mechanical damageFEBS JOURNAL, Issue 11 2007Fumitaka Wada Transglutaminases are Ca2+ -dependent enzymes that post-translationally modify proteins by crosslinking or polyamination at specific polypeptide-bound glutamine residues. Physarum polycephalum, an acellular slime mold, is the evolutionarily lowest organism expressing a transglutimase whose primary structure is similar to that of mammalian transglutimases. We observed transglutimase reaction products at injured sites in Physarum macroplasmodia upon mechanical damage. With use of a biotin-labeled primary amine, three major proteins constituting possible transglutimase substrates were affinity-purified from the damaged slime mold. The purified proteins were Physarum actin, a 40 kDa Ca2+ -binding protein with four EF-hand motifs (CBP40), and a novel 33 kDa protein highly homologous to the eukaryotic adenine nucleotide translocator, which is expressed in mitochondria. Immunochemical analysis of extracts from the damaged macroplasmodia indicated that CBP40 is partly dimerized, whereas the other proteins migrated as monomers on SDS/PAGE. Of the three proteins, CBP40 accumulated most significantly around injured areas, as observed by immunofluoresence. These results suggested that transglutimase reactions function in the response to mechanical injury. [source] An ice-binding protein from an Antarctic sea ice bacteriumFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007James A. Raymond Abstract An Antarctic sea ice bacterium of the Gram-negative genus Colwellia, strain SLW05, produces an extracellular substance that changes the morphology of growing ice. The active substance was identified as a ,25-kDa protein that was purified through its affinity for ice. The full gene sequence was determined and was found to encode a 253-amino acid protein with a calculated molecular mass of 26 350 Da. The predicted amino acid sequence is similar to predicted sequences of ice-binding proteins recently found in two species of sea ice diatoms and a species of snow mold. A recombinant ice-binding protein showed ice-binding activity and ice recrystallization inhibition activity. The protein is much smaller than bacterial ice-nucleating proteins and antifreeze proteins that have been previously described. The function of the protein is unknown but it may act as an ice recrystallization inhibitor to protect membranes in the frozen state. [source] Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon ResonanceADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Dehui Wan Abstract A flexible surface plasmon resonance (SPR)-based scattering waveguide sensor is prepared by directly imprinting hollow gold nanoparticles (NPs) and solid gold NPs onto flexible polycarbonate (PC) plates,without any surface modification,using a modified reversal nanoimprint lithography technology. Controlling the imprinting conditions, including temperature and pressure, allows for the fine adjustment of the depths of the embedded metal NPs and their SPR properties. This patterning approach exhibits a resolution down to the submicrometer level. A 3D finite-difference time domain simulation is used to examine the optical behavior of light propagating parallel to the air/substrate interface within the near-field regime. Consistent with the simulations, almost an order of magnitude enhancement in the scattering signal after transferring the metal NPs from the glass mold to the PC substrate is obtained experimentally. The enhanced signal is attributed to the particles' strong scattering of the guiding-mode waves (within the waveguide) and the evanescent wave (above the waveguide) simultaneously. Finally, the imprinting conditions are optimized to obtain a strongly scattering bio/chemical waveguide sensor. [source] Detachment Lithography of Photosensitive Polymers: A Route to Fabricating Three-Dimensional StructuresADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Junghoon Yeom Abstract A technique to create arrays of micrometer-sized patterns of photosensitive polymers on the surface of elastomeric stamps and to transfer these patterns to planar and nonplanar substrates is presented. The photosensitive polymers are initially patterned through detachment lithography (DL), which utilizes the difference in adhesion forces to induce the mechanical failure in the film along the edges of the protruded parts of the mold. A polydimethylsiloxane (PDMS) stamp with a kinetically and thermally adjustable adhesion and conformal contact can transfer the detached patterns to etched or curved substrates, as well as planar ones. These printed patterns remain photochemically active for further modification via photolithography, and/or can serve as resists for subsequent etching or deposition, such that photolithography can be used on highly nonconformal and nonplanar surfaces. Various 3D structures fabricated using the process have potential applications in MEMS (micro-electromechanical systems) sensors/actuators, optical devices, and microfluidics. [source] Capillary Force Lithography: A Versatile Tool for Structured Biomaterials Interface Towards Cell and Tissue Engineering,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Kahp-Yang Suh Abstract This Feature Article aims to provide an in-depth overview of the recently developed molding technologies termed capillary force lithography (CFL) that can be used to control the cellular microenvironment towards cell and tissue engineering. Patterned polymer films provide a fertile ground for controlling various aspects of the cellular microenvironment such as cell,substrate and cell,cell interactions at the micro- and nanoscale. Patterning thin polymer films by molding typically involves several physical forces such as capillary, hydrostatic, and dispersion forces. If these forces are precisely controlled, the polymer films can be molded into the features of a polymeric mold with high pattern fidelity and physical integrity. The patterns can be made either with the substrate surface clearly exposed or unexposed depending on the pattern size and material properties used in the patterning. The former (exposed substrate) can be used to adhere proteins or cells on pre-defined locations of a substrate or within a microfluidic channel using an adhesion-repelling polymer such as poly(ethylene glycol) (PEG)-based polymer and hyaluronic acid (HA). Also, the patterns can be used to co-culture different cells types with molding-assisted layer-by-layer deposition. In comparison, the latter (unexposed substrate) can be used to control the biophysical surrounding of a cell with tailored mechanical properties of the material. The surface micropatterns can be used to engineer cellular and multi-cellular architecture, resulting in changes of the cell shape and the cytoskeletal structures. Also, the nanoscale patterns can be used to affect various aspects of the cellular behavior, such as adhesion, proliferation, migration, and differentiation. [source] Is management by objectives obsolete?GLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 4 2009William F. Roth Management by Objectives has been part of corporate dogma for many decades. But as its touted strengths rapidly become liabilities in the new global century, more empowering and flexible approaches sprout up as promising new models for performance management. The author examines the dampening effect Management by Objectives can have on creativity, teamwork, and the ability to respond to changes in the business. He also presents two cases of organizations that broke out of the mold: W.L. Gore and Associates' innovative approach to self-managing teams and Bridgeport Paper Company's even bolder experiment, in which employees developed and implemented a team-based organizational structure and team-directed processes for decision making, hiring and promotion, training, performance management (without MBO), rewards, and cross-team communication and integration. © 2009 Wiley Periodicals, Inc. [source] Synthesis of N -Substituted (3S,4S)- and (3R,4R)-Pyrrolidine-3,4-diols: Search for New Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 12 2004Robert N -Substituted (3S,4S)- and (3R,4R)-pyrrolidine-3,4-diols 9 and 10, respectively, were derived from (+)- L - and (,)- D -tartaric acid, respectively. Compounds 9k, 9l, and 9m with the N -substituents, BnNH(CH2)2, 4-PhC6H4CH2NH(CH2)2 and 4-ClC6H4CH2NH(CH2)2, respectively, showed modest inhibitory activities toward , - D -amyloglucosidases from Aspergillus niger and from Rhizopus mold (Table,1). Unexpectedly, several (3R,4R)-pyrrolidine-3,4-diols 10 showed inhibitory activities toward , - D -mannosidases from almonds and from jack bean (Table,3). N -Substitution by the NH2(CH2)2 group, i.e., 10g, led to the highest potency. [source] Risk factors for mold in housing: a national surveyINDOOR AIR, Issue 6 2005P. Howden-Chapman First page of article [source] An Outbreak of Respiratory Diseases among Workers at a Water-Damaged Building , A Case ReportINDOOR AIR, Issue 3 2000MARKKU SEURI Abstract We describe a military hospital building with severe, repeated and enduring water and mold damage, and the symptoms and diseases found among 14 persons who were employed at the building. The exposure of the employees was evaluated by measuring the serum immunoglobulin G (IgG)-antibodies against eight spieces of mold and yeast common in Finnish water and mold damaged buildings and by sampling airborne viable microbes within the hospital. The most abundant spieces was Sporobolomyces salmonicolor. All but one of the employees reported some building-related symptoms, the most common being a cough which was reported by nine subjects. Four new cases of asthma, confirmed by S. salmonicolor inhalation provocation tests, one of whom was also found to have alveolitis, were found among the hospital personnel. In addition, seven other workers with newly diagnosed rhinitis reacted positively in nasal S. salmonicolor provocation tests. Skin prick tests by Sporobolomyces were negative among all 14 workers. Exposure of the workers to mold and yeast in the indoor air caused an outbreak of occupational diseases, including asthma, rhinitis and alveolitis. The diseases were not immunoglobulin E (IgE)-mediated but might have been borne by some other, as yet unexplained, mechanism. [source] Explicit coupled thermo-mechanical finite element model of steel solidificationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2009Seid Koric Abstract The explicit finite element method is applied in this work to simulate the coupled and highly non-linear thermo-mechanical phenomena that occur during steel solidification in continuous casting processes. Variable mass scaling is used to efficiently model these processes in their natural time scale using a Lagrangian formulation. An efficient and robust local,global viscoplastic integration scheme (Int. J. Numer. Meth. Engng 2006; 66:1955,1989) to solve the highly temperature- and rate-dependent elastic,viscoplastic constitutive equations of solidifying steel has been implemented into the commercial software ABAQUS/Explicit (ABAQUS User Manuals v6.7. Simulia Inc., 2007) using a VUMAT subroutine. The model is first verified with a known semi-analytical solution from Weiner and Boley (J. Mech. Phys. Solids 1963; 11:145,154). It is then applied to simulate temperature and stress development in solidifying shell sections in continuous casting molds using realistic temperature-dependent properties and including the effects of ferrostatic pressure, narrow face taper, and mechanical contact. Example simulations include a fully coupled thermo-mechanical analysis of a billet-casting and thin-slab casting in a funnel mold. Explicit temperature and stress results are compared with the results of an implicit formulation and computing times are benchmarked for different problem sizes and different numbers of processor cores. The explicit formulation exhibits significant advantages for this class of contact-solidification problems, especially with large domains on the latest parallel computing platforms. Copyright © 2008 John Wiley & Sons, Ltd. [source] Numerical simulation of mold filling in injection molding using a three-dimensional finite volume approachINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2001Rong-yeu Chang Abstract This work presents an implicit finite volume approach to simulate the three-dimensional mold filling problems encountered during the injection molding. The described numerical model deals with the three-dimensional isothermal flow of incompressible, high-viscous Newtonian fluids with moving interfaces. The collocated finite volume method and the SIMPLE segregated algorithm are used to discretize and solve the Navier,Stokes equation. In addition, a bounded compressive high-resolution differencing scheme is adopted to solve the advection equation to capture the interface on a Eulerian framework. This approach effectively solves the flow field in terms of CPU time and memory storage as well as the complicated three-dimensional melt front topology. Several two- and three-dimensional examples are presented to validate the presented approach and illustrate its capabilities. This method can more accurately predict the critical three-dimensional phenomena encountered during mold filling than the existing Hele,Shaw analysis model. The presented numerical approach has been proven to be a highly effective and flexible tool for simulating mold filling problems. Copyright © 2001 John Wiley & Sons, Ltd. [source] Texture Analysis and Finite Element Modeling of Operational Stresses in Ceramic Injection Molding Components for High-Pressure PumpsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2005Martin Wenzelburger Texturization of microstructures in ceramic components during injection of thermoplastic feedstocks into the mold is a well-known problem in ceramic injection molding (CIM) technology. The influences of textures on the mechanical properties of components with anisotropic properties, which depend on crystallite structure and orientation, usually involve weakening of the structure by the formation of separation planes and accumulation of stresses, which can lead to crack initiation and subcritical failure. A light optical texture analysis technique was developed for the analysis of thin section preparations from optically anisotropic ceramic materials. An internal Al2O3 gear rim for high-pressure gear pumps that is manufactured by CIM was chosen for the evaluation of this technique. Components were produced from thermoplastic ceramic feedstocks with different rheological behavior. Thin sections were prepared from the sintered parts. The texture was analyzed by polarized transmission light microscopy of the thin sections and colorimetric analysis of the crystal orientation. For the evaluation of the component properties, function, and lifetime, operating tests on a test bench were carried out as well as finite element (FE) simulation of the stress distribution in the components under operational load with regard to the texturization. The results were used for the localization of stress gradients and their comparison and correlation to the texturization. The functionality of this texture analysis method was proved by the tests, and it is expected to be a convenient novel method for the analysis and optimization of the parameters in CIM processes and the design of injection gate and mold. [source] Scanning electron microscopic observation of oil/wax/water/surfactant systemINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2005K. Ikuta We observed the internal structure of an oil/wax/water/surfactant system using a scanning electron microscope to investigate the relationship between its hardness and state of wax crystal. The molten wax (hydrogenated jojoba oil, ceresin, polyethylene wax, carnauba wax, or microcrystalline wax) was cast in a home-made spiral mold of aluminum foil for preparing the test specimen for SEM observation. In hydrogenated jojoba oil a fine frame-like crystal structure, the so-called ,card-house structure,' was observed but not in other waxes. The mixture of hydrogenated jojoba oil and water showed a few small droplets deposited on the roundish wax frame-like structure. On the other hand, waxes other than hydrogenated jojoba oil did not change their internal structure when they were mixed with water. This result suggested that hydrogenated jojoba oil showed uniquely high affinity for water. In the system of oil, water, surfactant, and various kinds of waxes, their crystal structure, hardness, and the shape of dispersed water particles were remarkably changed with the combination of waxes. In the system with ceresin and carnauba wax, the hardness measured by a card-tension meter was high, and the internal crystal structure was fine and amorphous. The water particle in the ceresin and carnauba wax system had a smaller diameter than that in the system containing hydrogenated jojoba oil. The system containing hydrogenated jojoba oil showed a card house-like wax crystal structure without high hardness. It was considered that the wax crystal structure played an important role in providing hardness and in contributing to the water distribution in the oil/wax/water/surfactant system. [source] Online control of the injection molding process based on process variablesADVANCES IN POLYMER TECHNOLOGY, Issue 2 2009Walter Michaeli Abstract The conventional control of the injection molding process is based on machine variables, which cannot sufficiently characterize the course of the process. Hence, a system that controls the injection molding process based on process variables has been developed at the Institute of Plastics Processing at RWTH Aachen University during the last years. It controls the quality determining process variable cavity pressure directly and realizes a desired course of cavity pressure in the injection and holding pressure phases. The cavity pressure course in the holding pressure phase is controlled online on the basis of pvT behavior of the processed plastic material. Thus, an optimal course of the process in the pvT diagram can be guaranteed and the quality constancy of the molded parts can be clearly increased. Using the pvT-based process control, the effect of varying mold and melt temperatures on the molded part weight can be decreased by about 90% compared with the conventional process control. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:65,76, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20153 [source] Improved thermal design of a compression moldADVANCES IN POLYMER TECHNOLOGY, Issue 2 2007Maria A. Kuczmarski Abstract An analysis of the heat transfer in a tool for producing neat resin disks was conducted to determine how to bring about a better agreement between the tool temperature and the applied temperature profile. Using the commercial code FLUENT to investigate the relative effects of heat conduction into the tool and heat loss from the tool by convection, it was shown that convective heat transfer appears more important than conduction in controlling the tool performance. Decreasing the height of the tool was predicted to decrease the heat losses by convection. Redesigning of the tool based on this analysis resulted in the tool experiencing the applied temperature profile. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:86,99, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20091 [source] A preliminary study on bladder-assisted rotomolding of thermoplastic polymer compositesADVANCES IN POLYMER TECHNOLOGY, Issue 1 2007A. Salomi Abstract In this preliminary work, a new process is examined for manufacturing hollow parts from continuous fiber-reinforced thermoplastic polymer. The new process combines the basic idea of bag forming (or bladder-assisted forming) with the rotation of the mold for the processing of thermoplastic matrix composites. A pressurized membrane is used to compact the composite on the inner wall of a mold, which is placed inside a forced convection oven. The mold is removed from the oven for the cooling stage. The process was initially developed by using a thermoplastic pre-preg obtained using yarns of commingled E-glass fibers with isotactic polypropylene (iPP). A preliminary characterization of the thermoplastic composite showed that the material can be consolidated with pressures as low as 0.01 MPa, which is readily achievable with the process of this study. The design of the mold and membrane was carried out on the basis of both structural analysis of the aluminum shell and thermal analysis of the mold. The mold thickness is of great importance with respect to both the maximum pressure allowed in the process and the overall cycle time. Molding was performed on stacks of three and six layers of yarn, varying the applied pressure between 0.01 and 0.05 MPa and maximum temperature of the internal air between 185°C and 215°C. The composite shells obtained under different processing conditions were characterized in terms of physical and mechanical properties. Mechanical properties comparable with those obtained by compression molding and vacuum bagging were obtained. The maximum values obtained are 12.1 GPa and 290 MPa for the flexural modulus and the flexural strength, respectively. Furthermore, the results obtained show that mechanical properties improve with increasing the pressure during the cycle and with the maximum temperature used in the process. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:21,32, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20085 [source] Cavity pressure control during cooling in plastic injection moldingADVANCES IN POLYMER TECHNOLOGY, Issue 3 2006B. Pramujati Abstract Cavity pressure control during filling, packing, and cooling phases is imperative for maintaining product quality in injection molding process. This paper presents the design and implementation of a strategy to control cavity pressure profile during the cooling phase. In order to do this, a controlled variable parameter was defined to be the time constant , of the pressure profile. This parameter can be used effectively to control the shape of the cavity pressure over the cooling cycle. The coolant flow rate through the mold was used as the manipulated variable. A predictive control system was designed and implemented successfully to allow monitoring and control of , at several setpoints ,sp resulting in good and effective cavity pressure control. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25:170,181, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20068 [source] | ||||||||||||||||||||||||||||||||||||||||