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Temperature Control (temperature + control)
Terms modified by Temperature Control Selected AbstractsDependency of Tritium Retention in Graphite on Temperature Control of Molecular DynamicsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3-5 2010A. Ito Abstract We have investigated the carbon plasma facing material and hydrogen atom interaction by the use of molecular dynamics simulation to clarify chemical erosion processes on divertor plate. The present paper is our first try at elucidation of temperature dependence by the molecular dynamics. Temperature was controlled by using Langevin thermostat method. As a result, the retention of hydrogen atom achieve steady state, and the CH4 was generated, which was not found MD simulations without a temperature control method. About 30 percent of injected hydrogen atoms are retained. CH4 yields has a peak at 600 K, which accords with experimental results. A dominant path of CH4 generation found by the present molecular dynamics simulation is as follows: a CH is detached from eroded surface and then it grows into CH4 adsorbing hydrogen atoms via CH2 and CH3. In addition, we propose the problem that the hydrogen atom retention and CH,, yields depend on the thermal relaxation time in MD simulation using temperature control methods (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxygen and Temperature Control during the Cultivation of Microorganisms using Substrate FeedingENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2007J. Vanags Aerobic fermentation via substrate feeding controlled by O2 and temperature supplements the tools for the experimental and possibly industrial use. This substrate-feeding algorithm was realized with the help of the flexible Bioprocess controller BIO-2. [source] Improving Grape Quality Using Microwave Vacuum Drying Associated with Temperature ControlJOURNAL OF FOOD SCIENCE, Issue 1 2007C. D. Clary ABSTRACT:, Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r2= 0.942 for prediction of final moisture content and r2= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins. [source] Temperature Control in the Late Preterm Infant: A Comparison of Thermoregulation Following Two Bathing TechniquesJOURNAL OF OBSTETRIC, GYNECOLOGIC & NEONATAL NURSING, Issue 2010Newborn Care No abstract is available for this article. [source] High Incidence of Thrombus Formation Without Impedance Rise During Radiofrequency Ablation Using Electrode Temperature ControlPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2003KAGARI MATSUDAIRA The authors hypothesized that during RF ablation, the electrode to tissue interface temperature may significantly exceed electrode temperature in the presence of cooling blood flow and produce thrombus. In 12 anesthetized dogs, the skin over the thigh muscle was incised and raised to form a cradle that was superfused with heparinized canine blood(ACT > 350 s)at 37°C. A 7 Fr, 4-mm or 8-mm ablation electrode containing a thermocouple was held perpendicular to the thigh muscle at 10-g contact weight. Interface temperature was measured at opposite sides of the electrode using tiny optical probes. RF applications(n = 157)were delivered at an electrode temperature of 45°C, 55°C, 65°C, and 75°C for 60 seconds, with or without pulsatile blood flow (150 mL/min). Without blood flow, the interface temperature was similar to the electrode temperature. With blood flow, the interface temperature (side opposite blood flow) was up to 36°C and 57°C higher than the electrode temperature using the 4- and 8-mm electrodes, respectively. After each RF, the cradle was emptied and the electrode and interface were examined. Thrombus developed without impedance rise at an interface temperature as low as 73°C without blood flow and 80°C with blood flow (11/16 RFs at 65°C electrode temperature using 4 mm and 13/13 RFs at an electrode temperature of 55°C using an 8-mm electrode with blood flow). With blood flow, interface temperature markedly exceeded the electrode temperature and the difference was greater with an 8-mm electrode (due to greater electrode cooling). In the presence of blood flow, thrombus occurred without an impedance rise at an electrode temperature as low as 65°C with a 4-mm electrode and 55°C with an 8-mm electrode. (PACE 2003; 26:1227,1237) [source] Effect of Storage Temperature and Duration on the Behavior of Escherichia coli O157:H7 on Packaged Fresh-Cut Salad Containing Romaine and Iceberg LettuceJOURNAL OF FOOD SCIENCE, Issue 7 2010Yaguang Luo Abstract:, This study investigated the impact of storage temperature and duration on the fate of Escherichia coli O157:H7 on commercially packaged lettuce salads, and on product quality. Fresh-cut Romaine and Iceberg lettuce salads of different commercial brands were obtained from both retail and wholesale stores. The packages were cut open at one end, the lettuce salad inoculated with E. coli O157:H7 via a fine mist spray, and resealed with or without an initial N2 flush to match the original package atmospheric levels. The products were stored at 5 and 12 °C until their labeled "Best If Used By" dates, and the microbial counts and product quality were monitored periodically. The results indicate that storage at 5 °C allowed E. coli O157:H7 to survive, but limited its growth, whereas storage at 12 °C facilitated the proliferation of E. coli O157:H7. There was more than 2.0 log CFU/g increase in E. coli O157:H7 populations on lettuce when held at 12 °C for 3 d, followed by additional growth during the remainder of the storage period. Although there was eventually a significant decline in visual quality of lettuce held at 12 °C, the quality of this lettuce was still fully acceptable when E. coli O157:H7 growth reached a statistically significant level. Therefore, maintaining fresh-cut products at 5 °C or below is critical for reducing the food safety risks as E. coli O157:H7 grows at a rapid, temperature-dependent rate prior to significant quality deterioration. Practical Application:, Specific information regarding the effect of temperature on pathogen growth on leafy greens is needed to develop science-based food safety guidelines and practices by the regulatory agencies and produce industry. Temperature control is commonly thought to promote quality of leafy greens, not safety, based at least partially on a theory that product quality deterioration precedes pathogen growth at elevated temperatures. This prevalent attitude results in temperature abuse incidents being frequently overlooked in the supply chain. This study demonstrates that human pathogens, such as E. coli O157:H7, can grow significantly on commercially packaged lettuce salads while the product's visual quality is fully acceptable. Packaged fresh-cut salads are marketed as "ready-to-eat" while lacking an effective pathogen kill step during their preparation. Thus, maintaining storage temperature at 5 °C or below is critical to prevent pathogen proliferation and mitigate food safety risks should pathogen contamination inadvertently occur during crop growth or postharvest fresh-cut processing. [source] Distillation Tower with Distributed Control Strategy: Feed Temperature LoadsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2007C. Marangoni Abstract Distillation towers require control systems adjusted to rapidly reject loads. Temperature control of these units is normally carried out at the bottom and top of the column, increasing the tower response time. In this paper, a change in this temperature control configuration is proposed through the introduction of heating points distributed among the trays throughout the column. The proposed strategy was tested in an experimental unit with an ethanol-water mixture applying a conventional approach (control at bottom and top only) and the proposed distributed configuration (bottom, top and tower trays) with feed temperature disturbance. The results showed a significant reduction in the time required for the column to stabilize after the load introduction, compared with the conventional approach, making faster dynamics possible. [source] CE combined with rolling circle amplification for sensitive DNA detectionELECTROPHORESIS, Issue 2 2008Ni Li Abstract Here we describe an assay which combines CE with rolling circle amplification (RCA) for sensitive DNA detection and quantification. RCA is an isothermal DNA replication technique that generates a long ssDNA with tandem repeats. It requires simpler temperature control in reaction and offers higher sequence specificity and greater quantitation capability compared to other amplification technologies. In this study, RCA amplified the DNA target via a circular template, and the product was digested into monomers for CE analysis. Less than 2,fmol of the DNA target could easily be detected using this RCA-CE assay and the assay has a dynamic range of two orders of magnitudes. Moreover, simultaneous detection of both the target DNA and the internal standard was achieved by designing two padlock probes with different sizes, which could significantly improve the quantification accuracy. The RCA-CE assay is easy to perform, readily adaptable for detection of multiple targets because of the high resolution power of CE, and is compatible with other applications employing RCA as a signal amplification tool. Additionally, this assay can be used with a capillary array system to perform sensitive, high-throughput genetic screening. [source] Rich Phase Behavior in a Supramolecular Conducting Material Derived from an OrganogelatorADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Josep Puigmartí-Luis Abstract Organic conducting fiber-like materials hold great promise for the development of nanowires that can act as connections in miniature electronic devices, as an alternative to inorganic nanometer scale structures. This article presents a conducting organic tetrathiafulvalene-based supramolecular material which possesses a rich phase behavior with different packing of the molecules in the different forms, evidenced by electron spin resonance (ESR) spectroscopy. The distinct phases of conducting nanofibers can be easily fabricated through the temperature control of their preparation process from a xerogel by doping with iodine vapors. A total of four conducting phases have been identified conclusively using ESR spectroscopy as the key analytical tool. Three of the phases show a good long-term stability and areas in which the I,V curves have ohmic behavior when studied by current sensing (conducting) AFM. They offer promise for applications where electrical nanometer scale connections are required. [source] Molecular dynamics of the generation process of double-walled carbon nanotubes from peapodsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2006Yasushi Shibuta Abstract The generation process of a double-walled carbon nanotube (DWNT) from a "peapod" was studied by classical molecular dynamics simulation. Starting from a peapod structure, defined by five C60 molecules inside a (10,10) single-walled carbon nanotube (SWNT), polymerized fullerenes, a peanut-like structure and an almost nanotube-like structure were obtained under suitable conditions of temperature control. The mean distance between the two layers of the DWNT agreed with an experimental report that it is larger than the interlayer spacing found in multi-walled carbon nanotubes (MWNTs). In addition, the chirality dependence of the potential energy of a DWNT on the relative chirality of its constituent tubes was examined using a 6-12 Lennard-Jones potential. It was found that the potential energy depends only on the distance between the two layers, not on the relative chiralities. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 254,264, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20115 [source] Effectiveness of cutaneous warming systems on temperature control: meta-analysisJOURNAL OF ADVANCED NURSING, Issue 6 2010Cristina Maria Galvão galvão c.m., liang y. & clark a.m. (2010) Effectiveness of cutaneous warming systems on temperature control: meta-analysis. Journal of Advanced Nursing,66(6), 1196,1206. Abstract Title.,Effectiveness of cutaneous warming systems on temperature control: meta-analysis. Aim., This paper is a report of a meta-analysis to identify the effectiveness of different types of cutaneous warming systems in temperature control for patients undergoing elective surgery. Background., Hypothermia is a common and serious complication of surgery. Different cutaneous warming systems are used to prevent hypothermia during surgery but there have been no previous meta-analyses of the effectiveness of different warming systems in controlling temperature. Data sources., We conducted a search of the CINAHL (2000 to April 2009), Medline (2000 to April 2009), Embase (2000 to April 2009) and the Cochrane Register of Controlled Trials (2000 to April 2009) databases for randomized controlled trials published in English, Spanish and Portuguese. The primary outcome measure of interest was core body temperature. Methods., A systematic review incorporating meta-analysis was carried out. Results., From 329 papers, 23 trials compared warming systems. Forced-air warming systems had a strong tendency towards superior temperature control over passive insulation via cotton blankets (mean difference: 0·29°C; 95% confidence interval: ,0·02 to 0·59, three trials 292 patients) and radiant warming systems (mean difference: 0·16°C; 95% confidence interval: ,0·01 to 0·33, three trials, 161 patients). However, circulating water garments tended to be more effective than forced-air warming systems (mean difference: ,0·73°C; 95% confidence interval: ,1·51 to 0·05, I2 = 97%; four trials, 198 patients). Pooled results approached statistical significance and indicated clinically meaningful differences in temperature control. Conclusion., Current evidence suggests that circulating water garments offer better temperature control than forced-air warming systems, and both are more effective than passive warming devices. [source] A novel process for continuous thermal embossing of large-area nanopatterns onto polymer filmsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009Matthew D. Fagan Abstract Hot embossing and nanoimprinting processes are being widely practiced in industry. Fast and reliable production of micro/nanofeatured patterns on large-area polymer films is of a great importance. In this study, a novel roll-to-roll thermal imprinting process was developed, capable of providing a mold-heating rate of 125°C/s with sufficient temperature control to produce large-area patterns continuously at a rapid production rate. With this new process, selected micro/nano patterns were produced on a polyethylene terephthalate film at a production rate exceeding 1 m/min. The roller mold temperature played a profound role in affecting the replication quality. To achieve good feature transfer properties, an elevated roller mold temperature approaching the melting temperature of the polymer was found to be critical. Microcavity filling time calculation further revealed that the elevated roller mold temperature is also necessary for achieving a rapid film feed rate as desired in the continuous roll-to-roll process. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:246,256, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20167 [source] A simple and inexpensive capillary furnace for variable-temperature X-ray diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2008Christine Lavigueur An inexpensive capillary furnace has been developed for variable-temperature X-ray diffraction in transmission geometry of air-stable liquid crystals and other materials. It offers temperature control with fluctuations of less than ±1,K in the range of interest for these samples, from room temperature to near 573,K. Phases can be accessed through heating or cooling with no significant overshooting of the target temperature. The furnace is designed to fit on a classical goniometer, and can be controlled by any standard temperature controller. The simple design of this furnace means that it is both inexpensive to build and easy to operate. [source] TC -tuned biocompatible suspension of La0.73Sr0.27MnO3 for magnetic hyperthermiaJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008N. K. Prasad Abstract La1,xSrxMnO3, a ferromagnet with high magnetization and Curie temperature TC below 70°C, enables its use for magnetic hyperthermia treatment of cancer with a possibility of in vivo temperature control. We found that La0.73Sr0.27MnO3 particles of size range 20,100 nm showed saturation magnetization around 38 emu/g at 20 kOe and a TC value of 45°C. Aqueous suspension of these nanoparticles was prepared using a polymer, acrypol 934, and the biocompatibility of the suspension was examined using HeLa cells. A good heating ability of the magnetic suspension was obtained in the presence of AC magnetic field, and it was found to increase with the amplitude of field. The suspension having concentration of 0.66 mg/mL (e.g., 0.66 mg of nanoparticles with acropyl per milliliter of culture media) was observed to be biocompatible even after 96 h of treatment, as estimated by sulforhodamine B and trypan blue dye exclusion assays. Further, the treatment with the aforementioned concentration did not alter the microtubule cytoskeleton or the nucleus of the cells. However, the bare particles (concentration of 0.66 mg of nanoparticles per milliliter of culture media, but without acropyl) decreased the viability of cell significantly. Our in vitro studies suggest that the suspension (concentration of 0.66 mg/mL) may further be analyzed for in vivo studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Effect of Water Phase Salt Content and Storage Temperature on Listeria monocytogenes Survival in Chum Salmon (Oncorhynchus keta) Roe and Caviar (Ikura)JOURNAL OF FOOD SCIENCE, Issue 5 2007Joong-Han Shin ABSTRACT:, Salmon caviar, or ikura, is a ready-to-eat food prepared by curing the salmon roe in a brine solution. Other seasonings or flavorants may be added, depending upon the characteristics of the product desired. Listeria monocytogenes growth is a potential risk, since it can grow at high salt concentrations (>10%) and in some products at temperatures as low as 3 °C. Ikura was prepared from chum salmon (Oncorhynchus keta) roe by adding food-grade NaCl to yield water phase salt contents (WPS) of 0.22% (no added salt), 2.39%± 0.18%, 3.50%± 0.19%, and 4.36%± 0.36%. A cocktail containing L. monocytogenes (ATCC 19114, 7644, 19113) was incorporated into the ikura at 2 inoculum levels (log 2.4 and 4.2 CFU/g), and stored at 3 or 7 °C for up to 30 d. L. monocytogenes was recovered by plating onto modified Oxford media. Aerobic microflora were analyzed on plate count agar. Samples were tested at 0, 5, 10, 20, and 30 d. L. monocytogenes did not grow in chum salmon ikura held at 3 °C during 30 d at any salt level tested; however, the addition of salt at these levels did little to inhibit Listeria growth at 7 °C and counts reached 5 to 6 logs CFU/g. Components in the salmon egg intracellular fluid appear to inhibit the growth of L. monocytogenes. Total aerobic microflora levels were slightly lower in products with higher salt contents. These results indicate that temperature control is critical for ikura and similar products, but that products with lower salt contents can be safe, as long as good refrigeration is maintained. [source] Kinetic Parameter Estimation of Time-temperature Integrators Intended for Use with Packaged Fresh SeafoodJOURNAL OF FOOD SCIENCE, Issue 3 2004T. F. M ENDOZA ABSTRACT: The United States Food and Drug Administration (USFDA) considers any hermetically sealed package containing fresh seafood as a reduced oxygen package (ROP) if the oxygen transmission rate of the package is less than 10000 cm3/m2/d. USFDA's recent Import Alert nr 16-125 effectively bans the use of ROP for fresh seafood in the United States unless adequate temperature control and thermal history monitoring is used. Time-temperature integrators (TTI) were proposed as one potential method to satisfy this thermal monitoring requirement. Evaluation and selection of appropriate TTIs remains a difficult process for seafood manufacturers. Three commercially available TTIs (Vitsab M2-10, C2-10, and Fresh-Check TJ2) and 5 prototype TTIs (Avery Dennison) were evaluated for performance against the Skinner and Larkin (1998) botulinum toxin lag-time relationship. Isothermal treatments at 0°C, 5°C, 10°C, and 15°C were used to determine Arrhenius kinetic parameters of TTIs. Computer models were used to predict and compare actual TTI performance under dynamic thermal conditions. Results suggest that Vitsab M2-10 and Avery Dennison T126(2) and T126(4) TTIs may be used to predict safety of fresh seafood in ROP. [source] Nonlinear model predictive control for the polymorphic transformation of L -glutamic acid crystalsAICHE JOURNAL, Issue 10 2009Martin Wijaya Hermanto Abstract Polymorphism, a phenomenon where a substance can have more than one crystal forms, has recently become a major interest to the food, speciality chemical, and pharmaceutical industries. The different physical properties for polymorphs such as solubility, morphology, and dissolution rate may jeopardize operability or product quality, resulting in significant effort in controlling crystallization processes to ensure consistent production of the desired polymorph. Here, a nonlinear model predictive control (NMPC) strategy is developed for the polymorphic transformation of L -glutamic acid from the metastable ,-form to the stable ,-form crystals. The robustness of the proposed NMPC strategy to parameter perturbations is compared with temperature control (T-control), concentration control (C-control), and quadratic matrix control with successive linearization (SL-QDMC). Simulation studies show that T-control is the least robust, whereas C-control performs very robustly but long batch times may be required. SL-QDMC performs rather poorly even when there is no plant-model mismatch due to the high process nonlinearity, rendering successive linearization inaccurate. The NMPC strategy shows good overall robustness for two different control objectives, which were both within 7% of their optimal values, while satisfying all constraints on manipulated and state variables within the specified batch time. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Crystal temperature control in the Czochralski crystal growth processAICHE JOURNAL, Issue 1 2001Antonios Armaou This work proposes a control configuration and a nonlinear multivariable model-based feedback controller for the reduction of thermal gradients inside the crystal in the Czochralski crystal growth process after the crystal radius has reached its final value. Initially, a mathematical model which describes the evolution of the temperature inside the crystal in the radial and axial directions and accounts for radiative heat exchange between the crystal and its surroundings and motion of the crystal boundary is derived from first principles. This model is numericully solved using Galerkin's method and the behaviour of the crystal temperature is studied to obtain valuable insights which lead to the precise formulation of the control problem, the design of a new control configuration for the reduction of thermal gradients inside the crystal and the derivation of a simplified 1-D in a space dynamic model. Then, a model reduction procedure for partial differential equation systems with time-dependent spatial domains (Armaou and Christofides, 1999) based on a combination of Galerkin's method with approximate inertial manifolds is used to construct a fourth-order model that describes the dominant thermal dynamics of the Czochralski process. This low-order model is employed for the synthesis of a fourth-order nonlinear multivariable controller that can be readily implemented in practice. The proposed control scheme is successfully implemented on a Czochralski process used to produce a 0.7 m long silicon crystal with a radius of 0.05 m and is shown to significantly reduce the axial and radial thermal gradients inside the crystal. The robustness of the proposed controller with respect to model uncertainty is demonstrated through simulations. [source] Synthesis and characterization of high molecular weight hexafluoroisopropylidene-containing polybenzimidazole for high-temperature polymer electrolyte membrane fuel cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2009Guoqing Qian Abstract A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F-PBI) was synthesized from 3,3,-diaminobenzidine (TAB) and 2,2-bis(4-carboxyphenyl) hexafluoropropane (6F-diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F-PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064,4073, 2009 [source] Chiral analysis of milnacipran by a nonchiral HPLC , circular dichroism: Improvement of the linearity of dichroic response by temperature controlJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16-17 2008Marie Lecoeur-Lorin Abstract The determination of the enantiomeric excess (e.e.) of a basic drug has been investigated in LC using a nonchiral stationary phase and a circular dichroism (CD) detector in order to avoid expensive chiral columns. The CD detector records both dichroic (,,) and UV (,) signals at the same wavelength and calculates the anisotropy factor (g = ,,/,), which is linearly related to the e.e. The enantiomeric and chemical composition of a chiral drug can be simultaneously determined on a nonchiral HPLC support. However, the g factor from the CD signal is temperature dependent. Indeed, the temperature has an influence on the stability of the CD signal and the linear regression between g factor and the e.e. of 1R,2S -enantiomer. So, a decrease in temperature gives rise to an improvement of the above-mentioned linearity correlation. After optimization of chromatographic parameters (porous graphitic carbon-based column, methanol/ phosphate buffer as mobile phase) and selection of CD wavelength, a linear regression of g factor versus e.e. of 1R,2S -enantiomer was obtained at temperature-controlled CD detection and an LOQ of 94% was found. The enantiomeric composition of milnacipran was determined with good accuracy. [source] A small outbreak of listeriosis potentially linked to the consumption of imitation crab meatLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2000J.M. Farber A small outbreak of listeriosis involving two previously healthy adults occurred in Ontario. Food samples obtained from the refrigerator of the patients included imitation crab meat, canned black olives, macaroni and vegetable salad, spaghetti sauce with meatballs, mayonnaise and water. All of the samples except the water contained Listeria monocytogenes. The three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2·1 × 109, 1·1 × 107 and 1·3 × 106 cfu g,1, respectively. L. monocytogenes serotype 1/2b was isolated from the patients, as well as from the opened and unopened imitation crab meat. Molecular typing of the isolates by both randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) typing demonstrated the imitation crab meat and clinical strains to be indistinguishable. Challenge studies performed with a pool of L. monocytogenes strains showed that imitation crab meat, but not olives, supported growth of the organism. In this study we have shown for the first time the potential involvement of imitation crab meat in a small outbreak of listeriosis. In terms of disease prevention, temperature control is critical to prevent or reduce the growth of this foodborne pathogen. In addition, with refrigerated products having a long (> 30 d) shelf life, additional safety factors must be used to prevent the growth of foodborne pathogens such as L. monocytogenes. [source] Brain edema in liver failure: Basic physiologic principles and managementLIVER TRANSPLANTATION, Issue 11 2002Fin Stolze Larsen MD In patients with severe liver failure, brain edema is a frequent and serious complication that may result in high intracranial pressure and brain damage. This short article focuses on basic physiologic principles that determine water flux across the blood-brain barrier. Using the Starling equation, it is evident that both the osmotic and hydrostatic pressure gradients are imbalanced across the blood-brain barrier in patients with acute liver failure. This combination will tend to favor cerebral capillary water influx to the brain. In contrast, the disequilibration of the Starling forces seems to be less pronounced in patients with cirrhosis because the regulation of cerebral blood flow is preserved and the arterial ammonia concentration is lower compared with that of patients with acute liver failure. Treatments that are known to reverse high intracranial pressure tend to decrease the osmotic pressure gradients across the blood-brain barrier. Recent studies indicate that interventions that restrict cerebral blood flow, such as hyperventilation, hypothermia, and indomethacin, are also efficient in preventing edema and high intracranial pressure, probably by decreasing the transcapillary hydrostatic pressure gradient. In our opinion, it is important to recall that rational fluid therapy, adequate ventilation, and temperature control are of direct importance to controlling cerebral capillary water flux in patients with acute liver failure. These simple interventions should be secured before more advanced experimental technologies are instituted to treat these patients. [source] Novel Method of Producing Polymer Gels in Aqueous Solution Using UV IrradiationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2004Fumiyoshi Ikkai Abstract Summary: We developed a novel method of producing polymer gels in aqueous solution using UV irradiation. Persulfates were effective photosensitive initiators of polymerization and/or gelation of acryloyl-type monomers/polymers. The gelation was confirmed by an abrupt increase in light scattering intensity, ,I(q),T, at the gelation point. The gelation method entails significant advantages: it does not need any cross-linkers, temperature control (heating), and additives except the persulfate. The UV irradiation time dependence of light scattering intensity, ,I(q),T, for pre-gel solutions containing N -isopropylacrylamide (NIPAm) and/or ammonium persulfate (APS). [source] Photoperiodic and temperature control of nymphal development and induction of reproductive diapause in two predatory Orius bugs: interspecific and geographic differencesPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2008DMITRY L. MUSOLIN Abstract The effects of day-length and temperature on pre-adult growth and induction of reproductive diapause are studied in Orius sauteri and Orius minutus (Heteroptera: Anthocoridae) from northern (43.0°N, 141.4°E) and central (36.1°N, 140.1°E) Japan. In the north, at 20 °C, pre-adult growth is slower under an LD 14 : 10 h photoperiod than under shorter or longer photophases. At 24 and 28 °C, the longer photophases result in shorter pre-adult periods. Acceleration of nymphal growth by short days in autumn appears to be adaptive. In the central region, this response is less pronounced, suggesting that timing of adult emergence is less critical than in the north. Day length also influences the thermal requirements for pre-adult development. The slope of the regression line representing temperature dependence of pre-adult development is significantly smaller and the lower development threshold (LDT) is significantly lower under an LD 12 : 12 h photoperiod than under long-day conditions. The weaker dependence of nymphal growth on temperature and the lower LDT in autumn might be adaptive. In the north, increased temperature shifts the critical day length of diapause induction and suppresses the photoperiodic response in O. sauteri but not in O. minutus. Further south, the incidence of diapause in both species is low even under short-day conditions but the same interspecific difference is observed (i.e. increase of temperature affects the response in O. sauteri but not in O. minutus). This suggests seasonally earlier diapause induction with weaker temperature dependence in O. minutus than in O. sauteri. [source] Photoperiodic and temperature control of diapause induction and colour change in the southern green stink bug Nezara viridulaPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2003Dmitry L. Musolin Abstract. The effect of photoperiod and temperature on the duration of the nymphal period, diapause induction and colour change in adults of Nezara viridula (L.) (Heteroptera: Pentatomidae) from Japan was studied in the laboratory. At 20 °C, the developmental period for nymphs was significantly shorter under LD 10 : 14 h (short day) and LD 16 : 8 h (long day) than under intermediate photoperiods, whereas at 25 °C it was slightly shorter under intermediate than short- and long-day conditions. It is assumed that photoperiod-mediated acceleration of nymphal growth takes place in autumn when day-length is short and it is unlikely that nymphal development is affected by day-length under summer long-day and hot conditions. Nezara viridula has an adult diapause controlled by a long-day photoperiodic response. At 20 °C and 25 °C in both sexes, photoperiodic responses were similar and had thresholds close to 12.5 h, thus suggesting that the response is thermostable within this range of temperatures and day-length plays a leading role in diapause induction. Precopulation and preoviposition periods were significantly longer under near-critical regimes than under long-day ones. Short-day and near-critical photoperiods induced a gradual change of adult colour from green to brown/russet. The rate of colour change was significantly higher under LD 10 : 14 h than under LD 13 : 11 h, suggesting that the colour change is strongly associated with diapause induction. The incidences of diapause or dark colour did not vary among genetically determined colour morphs, indicating that these morphs have a similar tendency to enter diapause and change colour in response to short-day conditions. [source] Nonlinear temperature control of a batch suspension polymerization reactorPOLYMER ENGINEERING & SCIENCE, Issue 6 2002Mohammad Shahrokhi This paper concerns nonlinear temperature control of a batch polymerization reactor where suspension polymerization of methyl methacrylate (MMA) takes place. For this purpose, four control algorithms, namely, a fix proportional-integral (PI) controller, an adaptive proportional-integral-derivative (PID) controller and two globally linearizing control (GLC) schemes, one for known kinetic model (GLC-I) and the other for unknown kinetic model (GLC-II), are selected. The performances of these controllers are compared through simulation and real-time studies in the presence of different levels of parameter uncertainty. The results indicate that GLCI and GLC-II have better performances than fix PI and adaptive PID, especially in case of strong gel effect. The worst performance belongs to adaptive PID because of rapid model changes in gel effect region. GLC-II has a simpler structure than GLC-I and can be used without requiring the kinetic model. In implementation of GLC-I the closed loop observer should be used because of model uncertainties. [source] Robust computer-controlled system for intracytoplasmic sperm injection and subsequent cell electro-activationTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 1 2009K. K. Tan Abstract Introduction Intracytoplasmic sperm injection (ICSI) and the subsequent cell electro-activation process is a relatively new enhanced procedure to address male factor infertility. The current method involves the engagement of experienced embryologists for such a purpose. More advanced methodologies, which use high precision instrumentation tools, will speed up the whole procedure. Methods In this paper, the development of a computer-controlled system for ICSI and the subsequent cell electro-activation process is presented. The system is integrated to a microinjection workstation and piezo-actuator to perform the ICSI procedure, with vision capability to automatically position the components precisely. A micro-pump assembly is utilized for automatic medium refreshment and a heater plate assembly provides temperature control during the cell electro-activation process. The overall system is comprehensive, comprising modular functional components integrated within a hardware architecture. Results Experimental results on mice oocytes verified the effectiveness of the developed system over the current method. Conclusions Further improvements on the instrumentation tools will improve the robustness and overall performance of the developed system. Copyright © 2009 John Wiley & Sons, Ltd. [source] Application of two-loop robust control to air-conditioning systems,ASIAN JOURNAL OF CONTROL, Issue 6 2009Gongsheng Huang Abstract This paper presents the design and application of a two-loop robust controller for temperature control in air-conditioning systems. A Takagi-Sugeno fuzzy model with uncertain local models is developed to describe the associated nonlinearities and uncertainties in the operation of the air handling units. Parallel distributed compensation is used to design the global control law. The local control law consists of two loops: an inner-loop integral controller and an outer-loop min-max predictive controller with short prediction horizon. A discounting scheme is developed to weight the contribution of the two loops. Experimental results are presented which show that the proposed strategy can achieve acceptable control performance with a minimum of onsite tuning. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Untersuchungen zum Werkstoffverhalten des Feinkornbaustahls S 460 unter erhöhten TemperaturenBAUTECHNIK, Issue 10 2007Jörg Lange Prof. Dr.-Ing. Die Bestimmung der Tragfähigkeit von Bauteilen aus S 460 im Brandfall auf der Grundlage vereinfachter oder allgemeiner Berechnungsverfahren entsprechend EN 1993-1-2 [1] erfordert die Kenntnis der mechanischen Eigenschaften des hochfesten Feinkornbaustahls unter erhöhten Temperaturen. Hierzu wurden Untersuchungen an Probestäben aus einem normalisierend gewalzten S 460 N und einem thermomechanisch gewalzten S 460 M durchgeführt. Beide Stahlsorten unterscheiden sich sowohl in ihrer chemischen Zusammensetzung als auch in der Temperaturführung beim Walzen. Auf der Grundlage instationärer Warmkriechversuche wurden Werkstoffgesetze für den Temperaturbereich von 20 bis 900 °C hergeleitet. Die Untersuchungen zeigen eine im Vergleich zu S 460 N erhöhte Festigkeit des S 460 M bei hohen Temperaturen. Diese ist zurückzuführen auf die durch das thermomechanische Walzen verursachte Verfestigung und die Verringerung der Kriechgeschwindigkeit durch Niob- und Titanausscheidungen. Beim Vergleich der Ergebnisse mit den in EN 1993-1-2 [1] für S 460 angegebenen Werkstoffgesetzen erkennt man, dass diese sowohl die Festigkeit als auch die Steifigkeit des untersuchten S 460 N überschätzen. Examination of the mechanical properties of the microalloyed grain refined steel S 460 at elevated temperatures. To establish a basis for calculating the load-bearing capacity of steel members made of S 460 in fire, corresponding to EN 1993-1-2 [1], the mechanical properties of the microalloyed grain refined steel S 460 under high temperatures have been examined. Two different kinds of steel have been considered: a normalised rolled S 460 N and a thermomechanically rolled S 460 M, that differ in their chemical composition and the temperature control during the hot-rolling process. On the basis of transient state tensile tests, material laws have been derived for the temperature range from 20 to 900 °C. The test results show an increased strength of S 460 M at elevated temperatures in comparison to S 460 N. This is a result of the strain hardening caused by the thermomechanical deformation and the precipitates formed by niobium and titanium that constrain creep deformations. The data derived from the tests show that the stress-strain relationships given in EN 1993-1-2 [1] for S 460 overestimate both the strength and the stiffness of the examined S 460 N. [source] Ornithine decarboxylase activity of L929 cells after exposure to continuous wave or 50 Hz modulated radiofrequency radiation,a replication studyBIOELECTROMAGNETICS, Issue 7 2007A. Höytö Abstract A replication study with some extensions was made to confirm enhancement of ornithine decarboxylase (ODC) activity in murine L929 fibroblasts after radiofrequency (RF) field exposure reported in earlier studies. L929 cells purchased from two cell banks were exposed for 2, 8, or 24 h to continuous wave or DAMPS (burst modulated at 50 Hz, with 33% duty cycle) signals at specific absorption rate (SAR) levels of 2.5 or 6.0 W/kg. Exposures were carried out in Crawford and waveguide chambers, at frequencies 835 and 872 MHz, respectively. The results did not confirm findings of previous studies reporting increased ODC activity in RF-exposed cells. When Crawford cell exposure system was used, ODC activity was either not affected (in the case of 8 or 24 h exposures) or decreased after 2 h exposure at the highest SAR level (6 W/kg). The decrease was most pronounced when cooling with air flow was not used, and is most likely related to increased temperature. The minor methodological differences (use of antibiotics, increased sensitivity of ODC assay) are not likely to explain the inconsistency of the findings of the present and previous studies. Different results were obtained in experiments with the waveguide system that involves more efficient temperature control. In this exposure system, ODC activity was increased after 8 h exposure at 6 W/kg. Further studies are warranted to explore whether this finding reflects a true non-thermal effect. The present study did not provide evidence for modulation-specific effects reported in earlier studies. Bioelectromagnetics 28:501,508, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||