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Processing Steps (processing + step)
Selected AbstractsBulk Nanostructured Materials: Non-Mechanical Synthesis,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Yulia Ivanisenko An overview of the synthesis and processing techniques for bulk nanostructured materials that are based on "bottom-up" approaches is presented. Typically, these processes use nanoparticles, which can be produced by a variety of methods in the gas, liquid or solid state, as the basic building blocks. Their assembly into bulk nanostructured materials requires at least one more processing step, such as compaction or the formation of thick films. For certain nanostructures, film deposition techniques can also be employed. A wide range of nanostructures , from thick films with theoretical density to bulk nanocrystalline materials with nanoporosity , exhibiting novel structural and functional properties useful in many fields of applications are presented. Additionally, the properties of these bulk nanostructured materials can be categorized as either tailored, i.e., microstructure-dependent and inherently irreversible, or tunable, i.e., reversible by the application of an external field. Examples of both categories of properties are presented and the special role of the synthesis and processing routes to achieve the necessary nanostructures is emphasized. [source] Autophosphorylation of Archaeoglobus fulgidus Rio2 and crystal structures of its nucleotide,metal ion complexesFEBS JOURNAL, Issue 11 2005Nicole LaRonde-LeBlanc The highly conserved, atypical RIO serine protein kinases are found in all organisms, from archaea to man. In yeast, the kinase activity of Rio2 is necessary for the final processing step of maturing the 18S ribosomal rRNA. We have previously shown that the Rio2 protein from Archaeoglobus fulgidus contains both a small kinase domain and an N-terminal winged helix domain. Previously solved structures using crystals soaked in nucleotides and Mg2+ or Mn2+ showed bound nucleotide but no ordered metal ions, leading us to the conclusion that they did not represent an active conformation of the enzyme. To determine the functional form of Rio2, we crystallized it after incubation with ATP or ADP and Mn2+. Co-crystal structures of Rio2,ATP,Mn and Rio2,ADP,Mn were solved at 1.84 and 1.75 Å resolution, respectively. The ,-phosphate of ATP is firmly positioned in a manner clearly distinct from its location in canonical serine kinases. Comparison of the Rio2,ATP,Mn complex with the Rio2 structure with no added nucleotides and with the ADP complex indicates that a flexible portion of the Rio2 molecule becomes ordered through direct interaction between His126 and the ,-phosphate oxygen of ATP. Phosphopeptide mapping of the autophosphorylation site of Rio2 identified Ser128, within the flexible loop and directly adjacent to the part that becomes ordered in response to ATP, as the target. These results give us further information about the nature of the active site of Rio2 kinase and suggest a mechanism of regulation of its enzymatic activity. [source] Challenges and Progress in High-Throughput Screening of Polymer Mechanical Properties by IndentationADVANCED MATERIALS, Issue 35 2009Johannes M. Kranenburg Abstract Depth-sensing or instrumented indentation is an experimental characterization approach well-suited for high-throughput investigation of mechanical properties of polymeric materials. This is due to both the precision of force and displacement, and to the small material volumes required for quantitative analysis. Recently, considerable progress in the throughput (number of distinct material samples analyzed per unit time) of indentation experiments has been achieved, particularly for studies of elastic properties. Future challenges include improving the agreement between various macroscopic properties (elastic modulus, creep compliance, loss tangent, onset of nonlinear elasticity, energy dissipation, etc.) and their counterpart properties obtained by indentation. Sample preparation constitutes a major factor for both the accuracy of the results and the speed and efficiency of experimental throughput. It is important to appreciate how this processing step may influence the mechanical properties, in particular the onset of nonlinear elastic or plastic deformation, and how the processing may affect the agreement between the indentation results and their macroscopic analogues. [source] Paste extrusion control and its influence on pore size properties of PTFE membranesADVANCES IN POLYMER TECHNOLOGY, Issue 3 2007Radium Huang Abstract Polytetrafluoroethylene (PTFE) is a remarkable membrane material. Owing to its high-melting point, PTFE fine powder cannot be processed using conventional melting processing methods. Instead, techniques such as paste extrusion, rolling, and sintering have to be employed. Each processing step has an important influence on the final pore size quality within the membrane. In this paper, a PID controller (proportional-integral-derivative controller) was used to improve the properties of PTFE paste during the extrusion process and the quality of the PTFE membrane. A range of lubricant content (18, 20, and 22 wt%) was used to monitor the pressure drop at different extrusion speeds (0.5, 1, and 2 mm/s) and reduction ratios (RR = 26.47, 47.06, 80.06). It was found that a higher lubricant content and a higher reduction ratio resulted in a lower pressure drop. It was also found that a higher stretching temperature tends to result in larger pore size and broader pore size distribution at the same stretching rate. At a monitored and controlled constant low-extrusion speed, the porosity of PTFE membrane was increased from 38% to 55% and the mean pore size was decreased from 0.22 to 0.15 ,m because of less migration and more uniform distribution of lubricant during extrusion. Properties and the associated property uniformity of the PTFE extrudate affect the subsequent membrane-forming process and the final pore size and size distribution significantly. © 2008 Wiley Periodicals, Inc. Adv Polym Techn 26:163,172, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20099 [source] Influence of melt drawing on the morphology of one- and two-step processed LDPE/thermoplastic starch blendsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2003F. J. Rodriguez-Gonzalez Abstract In this study the morphology of LDPE/TPS blends prepared by a one-step extrusion process is compared to that obtained by reprocessing of the original blends. The influence of composition and melt drawing is examined. A novel methodology based on the form factor of the dispersed particle was used to estimate the equivalent spherical particle size of dispersed thermoplastic starch (TPS). This approach allows for the quantitative comparison of average dispersed phase particles regardless of their shape. Blends prepared in the one-step extrusion process show increased levels of anisotropy as a consequence of a combination of coalescence and particle deformation during melt drawing. Reprocessed materials demonstrate morphologies that are highly stable to a wide range of hot stretch ratio conditions. The TPS particles of reprocessed blends show no coalescence and a low degree of deformation. This phenomenon is explained by plasticizer evaporation resulting from the second processing step. The TPS is transformed from a highly deformable phase to one resembling a partially cross-linked material. These data indicate that the one-step processing of LDPE/TPS blends can be used to generate a wide range of highly elongated morphological structures. A two-step approach, analogous to typical compounding and shaping operations and involving controlled glycerol removal in the second step can be used to prepare a wide range of highly stable, more isotropic, dispersed particle morphologies. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 297,305, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10057 [source] ENUMERATION OF AEROMONAS FOR VERIFICATION OF THE HYGIENIC ADEQUACY OF SWINE CARCASS DRESSING PROCESSES,JOURNAL OF FOOD SAFETY, Issue 1 2000SHEW-LING YU ABSTRACT Populations of Aeromonas spp. and aerobic bacteria from dehairing equipment and from carcasses passing through different processing steps in a swine slaughtering plant were evaluated to identify the hygienic risks of each operation. Sponge samples were taken from the scraper flails in dehairing machines and the surface of the shackling table at pre- and post-operation times, with 20 samples from each location being collected at each time. Increased post-operation levels of Aeromonas spp. indicated a buildup and possible spread of these bacteria to carcasses. The belly skins of 40 dehaired carcasses were each sampled at five points along the process line which were after the shackling, after the final singeing, after the final polishing, after the final wash and after chilling. The levels of microbial contaminants on carcasses varied at each processing step. The heaviest contamination of carcasses with Aeromonas (1.88 log CFU/cm2) and aerobic bacteria (2.66 log CFU/cm2) occurred after shackling. Counts were reduced at other steps as a result of singeing, washing and chilling operations. However, singed carcasses were recontaminated with Aeromonas and aerobic bacteria during the polishing operation. Aeromonas hydrophila were the most prominent motile aeromonads (74.1%) recovered at the plant. The findings for Aeromonas spp. were similar to those for aerobic bacteria (r2= 0.9995) which suggested that Aeromonas spp. are appropriate indicators for assessing carcass dressing processes. [source] Generalized k -space decomposition with chemical shift correction for non-cartesian water-fat imagingMAGNETIC RESONANCE IN MEDICINE, Issue 5 2008Ethan K. Brodsky Abstract Chemical-shift artifacts associated with non-Cartesian imaging are more complex to model and less clinically acceptable than the bulk fat shift that occurs with conventional spin-warp Cartesian imaging. A novel k -space based iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) approach is introduced that decomposes multiple species while simultaneously correcting distortion of off-resonant species. The new signal model accounts for the additional phase accumulated by off-resonant spins at each point in the k -space acquisition trajectory. This phase can then be corrected by adjusting the decomposition matrix for each k -space point during the final IDEAL processing step with little increase in reconstruction time. The technique is demonstrated with water-fat decomposition using projection reconstruction (PR)/radial, spiral, and Cartesian spin-warp imaging of phantoms and human subjects, in each case achieving substantial correction of chemical-shift artifacts. Simulations of the point-spread-function (PSF) for off-resonant spins are examined to show the nature of the chemical-shift distortion for each acquisition. Also introduced is an approach to improve the signal model for species which have multiple resonant peaks. Many chemical species, including fat, have multiple resonant peaks, although such species are often approximated as a single peak. The improved multipeak decomposition is demonstrated with water-fat imaging, showing a substantial improvement in water-fat separation. Magn Reson Med 59:1151,1164, 2008. © 2008 Wiley-Liss, Inc. [source] Formation of a fibrillar morphology of crosslinked epoxy in a polystyrene continuous phase by reactive extrusionPOLYMER ENGINEERING & SCIENCE, Issue 4 2004Françoise Fenouillot An immiscible polymer blend where the dispersed phase is fibrillar was prepared by in situ crosslinking of the minor phase. A model polystyrene/epoxy-amine blend was selected on the basis of rheological (achievement of the fibrillar structure) and reactivity (fast crosslinking) criteria. The system was a polystyrene/diglycidyl ether of bisphenol A (DGEBA)-aminoethyl piperazine (AEP) blend. At the temperature of extrusion, 180°C, the DGEBA is immiscible in PS and heterogeneous material is obtained. The elongational flow imposed by drawing the extrudate at the die exit permitted controlled generation of a fibrillar morphology of the dispersed epoxy phase, with a fiber diameter of 1 ,m and an aspect ratio greater than 100. It was shown that when the amine comonomer was injected into the extruder, its reactivity with DGEBA at high temperature was high enough to ensure partial crosslinking of the epoxy. The fibrils were formed even though the gel point of the epoxy phase was exceeded. However, above a certain critical insoluble fraction that we estimated to be between 45% and 70%, a coarsening of the structure appeared, caused by the decreasing deformability of the domains and their coalescence. Finally, for our system, the crosslinking of the dispersed phase up to 90% of insoluble fraction did not totally stabilize the morphology after the second processing step (injection molding). Polym. Eng. Sci. 44:625,637, 2004. © 2004 Society of Plastics Engineers. [source] Production of a Polyester Degrading Extracellular Hydrolase from Thermomonospora fuscaBIOTECHNOLOGY PROGRESS, Issue 5 2002Mona K. Gouda The production of a polyester-degrading hydrolase from the thermophilic actinomycete Thermomonospora fusca was investigated with regard to its potential technical application. Only in the presence of a polyester (random aliphatic-aromatic copolyester from 1,4-butanediol, terephthalic acid, and adipic acid with around 40,50 mol % terephthalic acid in the acid component), the excretion of the extracellular enzyme could be achieved with an optimized synthetic medium using pectin and NH4Cl as nitrogen source. Compared to complex media, a significantly higher specific activity at comparable volumetric yields could be obtained, thus reducing the expenditure for purification. The activity profile in the medium is controlled by a complex process involving (1) induction of enzyme excretion, (2) enzyme adsorption on the hydrophobic polyester surface, (3) inhibition of enzyme generation by monomers produced by polyester cleavage, and (4) enzyme denaturation. Diafiltration with cellulose acetate membranes as the sole downstream processing step led to a product of high purity and with sufficient yield (60% of total activity). Scaling-up from shaking flasks to a fermentor scale of 100 L revealed no specific problems. However, the excretion of the hydrolase by the actinomycete turned out to be inhibited by the degradation products (monomers) of the aliphatic-aromatic copolyester used as inductor for the enzyme production. The crude enzyme exhibited generally similar properties (temperature and pH optimum) as the highly purified hydrolase described previously; however, the storage capability and thermal stability is improved when the crude enzyme solution is diafiltrated. [source] SELECTING EFFECTIVE FEATURES AND RELATIONS FOR EFFICIENT MULTI-RELATIONAL CLASSIFICATIONCOMPUTATIONAL INTELLIGENCE, Issue 3 2010Jun He Feature selection is an essential data processing step to remove irrelevant and redundant attributes for shorter learning time, better accuracy, and better comprehensibility. A number of algorithms have been proposed in both data mining and machine learning areas. These algorithms are usually used in a single table environment, where data are stored in one relational table or one flat file. They are not suitable for a multi-relational environment, where data are stored in multiple tables joined to one another by semantic relationships. To address this problem, in this article, we propose a novel approach called,FARS,to conduct both,Feature,And,Relation,Selection for efficient multi-relational classification. Through this approach, we not only extend the traditional feature selection method to select relevant features from multi-relations, but also develop a new method to reconstruct the multi-relational database schema and eliminate irrelevant tables to improve classification performance further. The results of the experiments conducted on both real and synthetic databases show that,FARS,can effectively choose a small set of relevant features, thereby enhancing classification efficiency and prediction accuracy significantly. [source] Flux enhancement in TFC RO membranesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001Mark A. Kuehne The effects of varying processing conditions during fabrication of TFC RO membranes were systematically investigated. It was found that the membrane flux is greatly dependent on the processing steps that follow the synthesis of the thin film coating, such as washing, treatment with glycerol, and drying of the membrane. Glycerol is not simply a passive flux - p reserving agent, preventing loss of porosity during oven drying. In combination with a second oven drying step, glycerol actively enhances flux. Membrane flux can be similarly enhanced by treatment with solutions of organic salts, followed by oven drying. The effect of these treatments is quite large, increasing the flux by 30,70%, with no loss of salt rejection. Flux-enhancing additives were also used in the aqueous polyamine solution used to prepare the thin film coating. [source] Phase Transformations During High-Pressure Torsion of Pure Zr and of a Zr-2.5%Nb Alloy,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Alexander P. Zhilyaev Zirconium at normal conditions (room temperature and atmospheric pressure) has an HCP structure with lattice parameters a,=,3.2313,Å and c,=,5.1477,Å (,-phase). During loading under hydrostatic conditions in diamond anvil cells, a transition from the , -phase to an , -phase occurs at a pressure between 2 and 6 GPa and from , to , (bcc) at 30 GPa. It has been recently reported that the , to ,,+,, transformation might be induced by HPT processing. The resulting microstructures are stable at room temperature and atmospheric pressure. This paper explores the influence of previous processing steps and of composition in the feasibility of the HPT induced , to ,,+,, transformation. It will be shown that neither previous quenching nor high temperature HPT processing prevents the transformation from occurring during subsequent room temperature HPT. The addition of elements such as Nb also seems to favor the transformation. Understanding well the potential of HPT to stabilize high-pressure phases at normal conditions might be critical, as it will open a whole new range of applications for already existing materials. [source] Aluminium Foam Sandwich Panels: Manufacture, Metallurgy and ApplicationsADVANCED ENGINEERING MATERIALS, Issue 9 2008J. Banhart Abstract Sandwich panels consisting of a highly porous aluminium foam core and aluminium alloy face sheets are manufactured by roll-bonding aluminium alloy sheets to a densified mixture of metal powders , usually Al-Si or Al-Si-Cu alloys with 6,8% Si and 3,10% Cu , and titanium hydride, and foaming the resulting three-layer structure by a thermal treatment. We review the various processing steps of aluminium foam sandwich (AFS) and the metallurgical processes during foaming, compare the process to alternative ways to manufacture AFS, e.g. by adhesive bonding, and give an overview of the available literature. Two ways to treat AFS after foaming are presented, namely forging and age-hardening. Some current and potential applications are described and the market potential of AFS is assessed. [source] Pathogen safety of manufacturing processes for biological products: special emphasis on KOGENATE® BayerHAEMOPHILIA, Issue 2002D. C. Lee Summary., Manufacturers of human therapeutic proteins derived from biological sources continuously strive to improve the pathogen safety profiles of these products. Efforts to improve pathogen safety margins for these biological products are directed towards several areas within the manufacturing processes including: (a) sourcing and screening of raw materials (b) determining the potential for manufacturing processes to reduce pathogen titres, and (c) incorporating methods designed specifically to remove or inactivate contaminating pathogens. Methods that could potentially reduce pathogen titres are a major focus for many manufacturers. In general, these methods are grouped into two categories, pathogen clearance and pathogen inactivation. Assessments are performed on small-scale, laboratory simulations of the manufacturing process of interest that are spiked with a known amount of a selected pathogen. These studies provide estimates of the potential for a process step to remove or inactivate a particular pathogen. There are several pathogen clearance/inactivation methods that are inherent in manufacturing processes, however, some methods are intentionally incorporated into manufacturing for the sole purpose of reducing putative pathogen titres. Not only are well-known pathogens such as viruses targeted, but also suspected pathogens such as those associated with the transmissible spongiform encephalopathies (TSEs). The production processes for the isolation of several biological products, including recombinant KOGENATE® Bayer (Kogenate®FS), have been evaluated for the ability to reduce pathogen titres and/or have been designed to incorporate methods for reducing potential pathogen safety risks. Several processing steps with the potential to reduce pathogen titres have been identified. [source] Curving Nanostructures Using Extrinsic StressADVANCED MATERIALS, Issue 21 2010Jeong-Hyun Cho We demonstrate the concept of inducing stresses in thin films post-deposition (extrinsic stress) to curve nanostructures on demand. The remarkably high extrinsic stress, induced by triggering grain coalescence in Sn thin films, was used to self]assemble 3D nanostructures with radii of curvature as small as 20,nm. The fabrication methodology required only simple processing steps and the self]assembly process was highly parallel. Curved nanostructures with any desired pattern and both homogeneous (rings, tubes) and variable radii of curvature (spirals, talons) could be constructed. [source] FECAL COLIFORM CONTAMINATION OF BEEF CARCASSES DURING THE SLAUGHTERING PROCESSJOURNAL OF FOOD SAFETY, Issue 4 2001SUZAN YALÇIN ABSTRACT The purpose of this study was to determine the fecal coliform counts of beef carcasses during different stages in the slaughter process. A total of nine carcasses were selected at random in the abattoir. The samples were taken by excision from three different sites; rump, brisket and shoulder. The samples were collected from the same carcasses at four different stages of processing; after dressing, after evisceration, after washing and after chilling for 24 h in a chilling room. The processing steps did not increase the fecal coliform counts on the rump samples. There were no significant differences in the samples of rump and shoulder among different processing steps. The contamination level of the brisket after washing was significantly higher than other processing steps. Brisket and shoulder parts are critical points for microbiological sampling as these sites showed higher microbial counts after chilling steps. The data obtained have relevance for the planning of washing methods for the production of clean and safe carcasses. [source] ENUMERATION OF AEROMONAS FOR VERIFICATION OF THE HYGIENIC ADEQUACY OF SWINE CARCASS DRESSING PROCESSES,JOURNAL OF FOOD SAFETY, Issue 1 2000SHEW-LING YU ABSTRACT Populations of Aeromonas spp. and aerobic bacteria from dehairing equipment and from carcasses passing through different processing steps in a swine slaughtering plant were evaluated to identify the hygienic risks of each operation. Sponge samples were taken from the scraper flails in dehairing machines and the surface of the shackling table at pre- and post-operation times, with 20 samples from each location being collected at each time. Increased post-operation levels of Aeromonas spp. indicated a buildup and possible spread of these bacteria to carcasses. The belly skins of 40 dehaired carcasses were each sampled at five points along the process line which were after the shackling, after the final singeing, after the final polishing, after the final wash and after chilling. The levels of microbial contaminants on carcasses varied at each processing step. The heaviest contamination of carcasses with Aeromonas (1.88 log CFU/cm2) and aerobic bacteria (2.66 log CFU/cm2) occurred after shackling. Counts were reduced at other steps as a result of singeing, washing and chilling operations. However, singed carcasses were recontaminated with Aeromonas and aerobic bacteria during the polishing operation. Aeromonas hydrophila were the most prominent motile aeromonads (74.1%) recovered at the plant. The findings for Aeromonas spp. were similar to those for aerobic bacteria (r2= 0.9995) which suggested that Aeromonas spp. are appropriate indicators for assessing carcass dressing processes. [source] Injection-Salting of pre rigor Fillets of Atlantic Salmon (Salmo salar)JOURNAL OF FOOD SCIENCE, Issue 1 2007Sveinung Birkeland ABSTRACT:, The effects of temperature (,1, 4, and 10 °C), brine concentration (12% and 25% NaCl), injection volumes, and needle densities were investigated on fillet weight gain (%), salt content (%), fillet contraction (%), and muscle gaping in pre rigor brine-injected fillets of Atlantic salmon (Salmo salar). Increased brine concentration (12% to 25%) significantly increased the initial (< 5 min after injection) and final contraction (24 h after injection) of pre rigor fillets. Increased brine concentration significantly reduced weight gain and increased salt content but had no significant effect on muscle gaping. The temperatures tested did not significantly affect weight gain, fillet contraction, or gaping score. Significant regressions (P < 0.01) between the injection volume and weight gain (range: 2.5% to 15.5%) and salt content (range: 1.7% to 6.5%) were observed for injections of pre rigor fillets. Double injections significantly increased the weight gain and salt content compared to single injections. Initial fillet contraction measured 30 min after brine injection increased significantly (P < 0.01) with increasing brine injection volume but no significant difference in the fillet contraction was observed 12 h after brine injection (range: 7.9% to 8.9%). Brine-injected post rigor control fillets obtained higher weight gain, higher salt content, more muscle gaping, and significantly lower fillet contraction compared to the pre rigor injected fillets. Injection-salting is an applicable technology as a means to obtain satisfactory salt contents and homogenously distribute the salt into the muscle of pre rigor fillets of Atlantic salmon before further processing steps such as drying and smoking. [source] Workflow for managing impurities in an integrated crystallization processAICHE JOURNAL, Issue 3 2010Yuen S. Cheng Abstract A workflow consisting of experiments, modeling, and synthesis is presented for managing the impurity content in the product crystals of a crystallization process taking into consideration the entire train of crystallization and downstream processing steps. Experiments on solid,liquid equilibrium, impurity inclusion, washing, and deliquoring are designed in such a way that the experimental data or the model parameters derived from these data can be readily used for process design. Guidelines for experimental design and tradeoffs in process synthesis are discussed. The workflow is illustrated using the purification of Vitamin C (ascorbic acid) as a case study. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Shear-induced degradation of plasmid DNAJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2002C. S. Lengsfeld Abstract The majority of gene therapy clinical trials use plasmid DNA that is susceptible to shear-induced degradation. Many processing steps in the extraction, purification, and preparation of plasmid-based therapeutics can impart significant shear stress that can fracture the phosphodiester backbone of polynucleotides, and reduce biological activity. Much of the mechanistic work on shear degradation of DNA was conducted over 30 years ago, and we rely heavily on this early work in an attempt to explain the empirical observations of more recent investigations concerning the aerosolization of plasmids. Unfortunately, the sporadic reports of shear degradation in the literature use different experimental systems, making it difficult to quantitatively compare results and reach definitive mechanistic conclusions. In this review, we describe the forces imparted to DNA during shear stress, and use published data to quantitatively evaluate their relative effects. In addition, we discuss the effects of molecular weight, strain rate, particle size, flexibility, ionic strength, gas,liquid interfaces, and turbulence on the fluid flow degradation of supercoiled plasmid DNA. Finally, we speculate on computational methods that might allow degradation rates in different experimental systems to be predicted. © 2002 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:1581,1589, 2002 [source] THE IMPACT OF HOMOGENIZATION AND MICROFILTRATION ON RENNET-INDUCED GEL FORMATIONJOURNAL OF TEXTURE STUDIES, Issue 4 2008STEPHAN THOMANN ABSTRACT The effects of the independent variables, milk homogenization pressure (p1), concentration factor of milk microfiltration (i) and pH on the rheological properties of rennet milk gels were studied. Nondestructive oscillatory rheometry was used to determine rennet coagulation time (RCT), curd firming rate (CFR) and cutting time (CT). A central composite design, comprising two levels of i (1 and 2), pH (6.4 and 6.6) and p1 (0 and 8 MPa), was applied. Second-order polynomial models successfully described (R2 > 0.92) the relationship between processing parameters and rheological properties of the gels. pH had the most important influence on RCT, while CFR and CT were strongly influenced by i, pH and the interaction of i and pH. In contradiction to studies on active filler interactions for acid milk gels, a discrepancy was observed between results obtained by compression test and rheometry. Rennet gel firmness strongly decreased with a rise in p1 when measured using the compression test, whereby CFR increased with an increase in p1 when measured using rheometry. The latter result corresponds to higher storage modulus values after a certain time indicating higher gel stiffness. This effect was stronger for concentrated milk than for unconcentrated milk. PRACTICAL APPLICATIONS The use of microfiltration (MF) and homogenization may reduce raw material and processing time in conventional cheese manufacture. However, MF markedly influences milk composition, and homogenization alters the particle size distribution of fat globules. Hence, both technologies may influence rennet-induced gel formation, syneresis, cheese composition and quality. Curd firmness of homogenized milk is often too weak to resist the extensive curd treatment applied in semi-hard cheese manufacture which causes loss of curd fines during the syneresis process and finally decreases cheese yield. MF leads to high curd firmness if cutting is not performed at the appropriate time, which unnecessarily extends processing time. The study of the effect of the individual treatments, as well as of the combination of both on rennet-induced gel formation, is the first important step to evaluate their impact on further processing steps in cheese making. The combination of both technologies may overcome the antagonistic effect of the individual technology as low curd firmness due to homogenization can be compensated by MF that increases curd firmness and vice versa. [source] ZrW2O8,ZrO2 Continuous Functionally Graded Materials Fabricated by In Situ Reaction of ZrO2 and WO3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Li Sun ZrO2 powder and ZrO2+WO3 powder mixture were stacked, cocompacted, and cosintered in a cylindrical die, the processing steps commonly used to fabricate multilayer materials. The soak duration and the mass ratio among layers in the processing have been varied to yield a wide range of final sintered samples. At appropriate soak durations, the sintered samples resulted in continuous functionally graded materials (FGMs) made of ZrW2O8 and ZrO2. In other words, instead of the expected discrete, multiple-layered materials, the resulting samples are characterized by the axially, continuously varying physical properties. The continuous FGM structure is formed by several mechanisms: the balance between the reaction of ZrO2 and WO3 and the decomposition of ZrW2O8, as well as the sublimation and diffusion of WO3. The continuous FGMs can be utilized to reduce the thermal stress induced from a thermal gradient loading within a material system. This study shows that the processing steps typically used for multilayer FGMs can also be used to create continuous FGMs for some special material combinations. [source] FIB-Nanotomography of Particulate Systems,Part II: Particle Recognition and Effect of Boundary TruncationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006Beat Münch The focused ion beam-nanotomography (FIB-nt) technique presented in Part I of this article is a novel high-resolution three-dimensional (3D) microscopy method that opens new possibilities for the microstructural investigation of fine-grained granular materials. Specifically, FIB-nt data volumes allow particle size distributions (PSD) to be determined, and the current paper discusses all the processing steps required to obtain the PSD from 3D data. This includes particle recognition and the subsequent PSD estimation. A refined watershed approach for 3D particle recognition that tolerates concavities on the particle surfaces is presented. Particles at the edge of the 3D data volume are invariably clipped, and because the data volume is of a very limited size, this effect of boundary truncation seriously affects the PSD and needs to be corrected. Therefore, two basic approaches for the stereological correction of the truncation effects are proposed and validated on artificially modeled particle data. Finally, the suggested techniques are applied to real 3D-particle data from ordinary portland cement and the resulting PSDs compared with data from laser granulometry. [source] Pesticide residues in field-sprayed and processed fruits and vegetablesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2004María Jesús Chavarri Abstract This study was initiated to determine what residues of six insecticides (organochlorine, organophosphorus and pyrethroids) and four dithiocarbamate fungicides remained on raw agricultural commodities after harvest and to study the effect of the subsequent commercial processing on the residues. Sprayed crops of tomatoes, red peppers, asparagus, spinach, artichokes and peaches harvested after controlled field trials contained residues well below the maximum residue levels, except for lindane in tomatoes and acephate in artichoke. Commercial processing procedures led to large reductions in residue levels in the finished products. Washing removed all residual lindane, chlorpyrifos and cypermethrin from tomatoes. Chlorpyrifos residues were reduced by 67% during wood-fire roasting of peppers, and subsequent peeling removed all the remains. Peeling and blanching of asparagus reduced chlorpyrifos concentrations to undetectable levels. Processing of artichokes eliminated acephate and chlorpyrifos after blanching. Acephate in peaches survived successive processing steps until the final heat process that destroyed remaining residues. The net results can contribute to assure the consumer of a safe wholesome food supply. Copyright © 2004 Society of Chemical Industry [source] Investigations into the Chemical Modification of Polyolefin Surfaces by Radical Reactions during MoldingMACROMOLECULAR REACTION ENGINEERING, Issue 4 2007Jürgen Nagel Abstract The surfaces of polyolefin parts are usually modified by separate processing steps. In this paper, we investigate how an in situ surface modification of polyolefins could be realized during molding, based on radical reactions, by which a macromolecule with functional groups is grafted to the polyolefin surface. The temperature of the melt is used to initialize the reactions. The different steps of the radical reaction chain were analyzed using model reactions. A modifier composition consisting of dibenzoylperoxide, potassium persulfate and poly(vinyl alcohol) revealed to be suitable. This composition was used for injection molding experiments. The bondability of the injection molded parts was largely enhanced. [source] Twenty-five pitfalls in the analysis of diffusion MRI data,NMR IN BIOMEDICINE, Issue 7 2010Derek K. Jones Abstract Obtaining reliable data and drawing meaningful and robust inferences from diffusion MRI can be challenging and is subject to many pitfalls. The process of quantifying diffusion indices and eventually comparing them between groups of subjects and/or correlating them with other parameters starts at the acquisition of the raw data, followed by a long pipeline of image processing steps. Each one of these steps is susceptible to sources of bias, which may not only limit the accuracy and precision, but can lead to substantial errors. This article provides a detailed review of the steps along the analysis pipeline and their associated pitfalls. These are grouped into 1 pre-processing of data; 2 estimation of the tensor; 3 derivation of voxelwise quantitative parameters; 4 strategies for extracting quantitative parameters; and finally 5 intra-subject and inter-subject comparison, including region of interest, histogram, tract-specific and voxel-based analyses. The article covers important aspects of diffusion MRI analysis, such as motion correction, susceptibility and eddy current distortion correction, model fitting, region of interest placement, histogram and voxel-based analysis. We have assembled 25 pitfalls (several previously unreported) into a single article, which should serve as a useful reference for those embarking on new diffusion MRI-based studies, and as a check for those who may already be running studies but may have overlooked some important confounds. While some of these problems are well known to diffusion experts, they might not be to other researchers wishing to undertake a clinical study based on diffusion MRI. Copyright © 2010 John Wiley & Sons, Ltd. [source] 6th International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & TechnologiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Bálint P The EXMATEC workshops are a series of biannial conferences with the aim to bring together research and development specialists involved in compound semiconductor material physics, chemistry, process technology, characterization and device fabrication. EXMATEC 2002 is the continuation of successful meetings, previously held in Lyon, Parma, Freiburg, Cardiff and Heraklion. The central topics were development, improvement and application of new and advanced methods in the fabrication and evaluation of compound semiconductor materials and structures to develop understanding of the interrelationship between structural, electrical and other material properties and device characteristics, such as performance, reliability, reproducibility, lifetime, yield, etc. The conference topics apply to all compound semiconductor materials (III,V, II,VI, IV,IV, II,IV,V2), related structures and processing steps (from substrate and epitaxial growth to complete devices) and cover instrumentation and characterization issues. The full Proceedings of EXMATEC 2002 are published in the second issue of the new journal series physica status solidi , conferences Vol. 0, No. 2 (2003). As one representative example of the topics presented at this conference, the cover picture of the present issue issue of phys. stat. sol. (a) shows the band scheme of a typical GaInAs/AlInAs superlattice quantum cascade laser, taken from the invited paper by Razeghi and Slivken [1]. [source] Adhesion of thermoplastic elastomer on surface treated aluminum by injection moldingPOLYMER ENGINEERING & SCIENCE, Issue 8 2007P.A. Fabrin Hybrid composites were prepared using insert injection molding without preheating. Thermoplastic elastomer (TPE) was overmolded on etched aluminum sheets having porous surface to provide large contact area between insert and TPE. The resulting bond strength was studied using a 180° peel test. The effect of aluminum microstructure and various processing steps of the surface treatment procedures on adhesion were studied. Maximum peel strength obtained was 9.33 N/cm using P2 treatment with alkaline-acid pretreatment. Lowest peel strength of 1.68 N/cm was achieved by alkaline,acid treatment. Increasing insert thickness lowers the peel strength since large heat capacity of thicker insert cools the melt and limits penetration of the melt to insert microcavities. At certain insert thickness microcavities are impregnated by the melt and no additional effect can be obtained by decreasing the insert thickness. POLYM. ENG. SCI., 47:1187,1191, 2007. © 2007 Society of Plastics Engineers [source] Interlaminar contact development during thermoplastic fusion bondingPOLYMER ENGINEERING & SCIENCE, Issue 2 2002F. Yang Fabrication of layered thermoplastics and thermoplastic-matrix composites using processes such as tow placement, tape laying, and resistance welding is fundamentally based on the principle of fusion bonding, which involves applying heat and pressure to contacting thermoplastic surfaces. One of the important processing steps,intimate contact development,is considered in this paper. Interlaminar intimate contact development has a strong dependency on the thermoplastic surface geometry. Profilometric measurements of common thermoplastic prepreg tows, such as AS4/PEEK and IM7/PIXA, show that surface roughness features appear at several length scales and that the surfaces have fractal asperity structures. In this paper, principles of fractal geometry are used to describe prepreg surfaces. Based on this description, a microscale fluid flow model is developed to relate a degree of intimate contact to the process parameters (pressure, temperature, and time) and the fractal parameters of the surface. The model development and comparisons with experimental data are presented and discussed. [source] Fabrication of multilayer ceramic membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009V.V. Zyryanov Abstract The development of multilayer mixed conducting oxide membranes on macroporous dead-end tubular composite glass/ceramic substrates is presented. Sol modification of glass/ceramic substrate enhances the performance of catalytic membrane reactor (CMR) with reduced thickness of ceramic layers. The shrinkage misfit between support and ceramic layers can be regulated by different processing steps including sol modification of substrate and preliminary annealing of ceramic powders. Nanopowders of compatible complex perovskites as membrane materials were obtained by mechanochemical synthesis. Porous and dense ceramic layers were supported onto the internal wall of substrate by slip casting of slurries comprised of the narrow fractions of agglomerated powders dispersed in organic media with addition of surfactants. For SrFeO3 -based dense perovskite ceramics, both dynamics of oxygen loss at high temperatures and mechanical properties were found to be affected by the presence of SrSO4 surface inclusions formed due to sulfur admixture in starting reactants. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. 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