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Heat
Kinds of Heat Terms modified by Heat Selected AbstractsMOISTURE SORPTION ISOTHERM, PROPERTIES OF SORBED WATER AND HEAT OF SORPTION OF SANDESH, AN INDIAN MILK PRODUCTJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2010J.K. SAHU ABSTRACT Moisture sorption isotherm of sandesh, one of the most popular milk products in India, was determined in terms of its moisture adsorption isotherms by gravimetrical method at 20 and 30C using various saturated salt solutions in the range of 11.2 to 97.2%. The isotherms obtained were of sigmoid shape and of the Brunauer,Emmett,Teller type. Out of three sorption models fitted to the experimental data, Caurie's model was found superior in interpreting the moisture adsorption characteristics of sandesh. The monolayer moisture content as calculated from the Caurie's model at 20 and 30C were 5.89% (dry basis [d.b.]) and 5.21% (d.b.), respectively. The values of isosteric heat of sorption as calculated from Clausius,Clapeyron equation was found to increase with decreasing moisture content at lower moisture content and approached the value of heat of vaporization of free water above 17.25% (d.b.). PRACTICAL APPLICATIONS The present paper describes basically the storage stability of sandesh. The sandesh is a heat,acid coagulated product of milk in Indian subcontinent and forms the part and parcel of social life, ceremonies and festivals. It has an excellent market potential and higher profit margin compared with other milk products like table butter, cheese and milk powder. Although Indian dairy industry has made rapid strides in the last few decades, there is no proper packaging system, developed so far, for storage of sandesh. Keeping pace with the growing consumers' demand for fresh, convenient and microbiologically free foods, design of proper packaging system is the need of the hour. The data presented in the paper will be very much essential for the researchers and research and development institutions for proper designing of packaging system for sandesh. [source] MODELING OF HEAT AND MASS TRANSFER DURING BAKING OF BISCUITSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2004MARIA ELENA SOSA-MORALES ABSTRACT Precooked biscuits (7 cm diameter × 2 cm thickness), preserved by freezing, were evaluated in a regional bakery. Heat and mass transfer during these processes and through the final baking were studied. Precooking was conducted at 180C for 18 min; convection and conduction were the predominant phenomena for heat transfer, with an ,, = 1.71 × 10,7 m2/s. Diffusion mechanism adequately modeled (r2 = 0.94, PEM < 2.5%) the moisture loss during cooking stage, with a D = 1.04 × 10,6 m2/s. The freezing point obtained inside a tunnel freezer (forced air at ,,40C), was , 6.73C, consistent with the predicted value. Volume changes were minimal during frozen storage because of high fat content and few variations in the freezer temperature. Final baking in conventional gas and microwave ovens were compared. Higher moisture loss and minimal color change occurred in the microwave baking. Instrumental texture of both final treatments were significantly different, in contrary to sensory evaluation (, = 0.05). The methods produced a good choice for product commercialization after baking. [source] NEW INSIGHT INTO THE SIGNALLING PATHWAYS OF HEAT STRESS-INDUCED MYOCARDIAL PRECONDITIONING: PROTEIN KINASE C, TRANSLOCATION AND HEAT SHOCK PROTEIN 27 PHOSPHORYLATIONCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2004Claire Arnaud SUMMARY 1.,Heat stress (HS) is known to induce delayed preconditioning against myocardial infarction 24 h later, but the exact signalling pathway of this response remains to be elucidated. In previous studies, we have shown evidence for the implication of protein kinase C (PKC) and p38 mitogen-activated protein kinase (MAPK) in the HS-induced reduction in infarct size. Furthermore, in their phosphorylated state, small heat shock proteins (Hsp27) seem to confer cytoskeletal protection. In the present study, we sought to determine the effect of HS on the subcellular distribution of PKC isoforms and on Hsp27 phosphorylation. 2.,Rats were subjected to either HS (42°C for 15 min; HS group) or sham anaesthesia (sham group) before their hearts were excised. Myocardial tissue extracts obtained 20 min or 24 h after HS were processed for western blot analysis. 3.,In the HS group, PKC, translocated from the cytosolic to the particulate fraction (4426 ± 128 vs 6258 ± 316 arbitrary units; P = 0.002). Chelerythrine (5 mg/kg, i.p.), a PKC inhibitor, abolished this translocation. Western blot analysis of Hsp27 24 h after HS showed a marked increase in protein expression and phosphorylation in the particulate fraction. 4.,In the present study, we have shown that HS induces the translocation of PKC, from the cytosolic to the particulate fraction. Along with our previous observation that PKC is a trigger of HS-induced myocardial preconditioning, the results of the present study suggest an important role of the , isoform of PKC in this cardioprotective mechanism. Furthermore, we have also demonstrated that the cytoprotective protein Hsp27 is phosphorylated following HS. Therefore, we can conclude that PKC and MAPK/Hsp27 are involved in the signalling pathway of HS-induced cardioprotection. [source] Cardiovascular function in the heat-stressed humanACTA PHYSIOLOGICA, Issue 4 2010C. G. Crandall Abstract Heat stress, whether passive (i.e. exposure to elevated environmental temperatures) or via exercise, results in pronounced cardiovascular adjustments that are necessary for adequate temperature regulation as well as perfusion of the exercising muscle, heart and brain. The available data suggest that generally during passive heat stress baroreflex control of heart rate and sympathetic nerve activity are unchanged, while baroreflex control of systemic vascular resistance may be impaired perhaps due to attenuated vasoconstrictor responsiveness of the cutaneous circulation. Heat stress improves left ventricular systolic function, evidenced by increased cardiac contractility, thereby maintaining stroke volume despite large reductions in ventricular filling pressures. Heat stress-induced reductions in cerebral perfusion likely contribute to the recognized effect of this thermal condition in reducing orthostatic tolerance, although the mechanism(s) by which this occurs is not completely understood. The combination of intense whole-body exercise and environmental heat stress or dehydration-induced hyperthermia results in significant cardiovascular strain prior to exhaustion, which is characterized by reductions in cardiac output, stroke volume, arterial pressure and blood flow to the brain, skin and exercising muscle. These alterations in cardiovascular function and regulation late in heat stress/dehydration exercise might involve the interplay of both local and central reflexes, the contribution of which is presently unresolved. [source] Influence of internal radiation on the heat transfer during growth of YAG single crystals by the Czochralski methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2003Z. Galazka Abstract Heat and mass transfer taking place during growth of Y3Al5O12 (YAG) crystals by the Czochralski method, including inner radiation, is analyzed numerically using a Finite Element Method. For inner radiative heat transfer through the crystal the band approximation model and real transmission characteristics, measured from obtained crystals, are used. The results reveal significant differences in temperature and melt flow for YAG crystals doped with different dopands influencing the optical properties of the crystals. When radiative heat transport through the crystal is taken into account the melt-crystal interface shape is different from that when the radiative transport is not included. Its deflection remains constant over a wide range of crystal rotation rates until it finally rapidly changes in a narrow range of rotation rates. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Severe periodontal damage by an ultrasonic endodontic device: a case reportDENTAL TRAUMATOLOGY, Issue 2 2007John D. Walters Abstract,,, Heat produced within a root canal during use of an ultrasonic instrument can be conducted through the dentin into periodontal ligament, bone and soft tissue. If severe in intensity or long in duration, it can induce damage to these tissues. This report describes a case in which an ultrasonic endodontic instrument apparently induced severe damage to alveolar bone, gingiva and nasal mucosa in a 42-year-old female. Overheating of a maxillary central incisor caused necrosis of soft tissue and bone on the facial and mesial aspects and triggered a protracted inflammatory response in the adjacent nasal cavity. To relieve the severe discomfort associated with this damage, the patient chose to have her maxillary incisors extracted and replaced by a removable partial denture. A defect in the soft tissue and bone was present at a follow-up visit 10 months after the extractions. While morbidity of this nature is rare, this case reinforces the need to maintain adequate cooling of ultrasonic instruments. [source] Heat or Cold Packs for Neck and Back Strain: A Randomized Controlled Trial of EfficacyACADEMIC EMERGENCY MEDICINE, Issue 5 2010Gregory Garra DO Abstract Objectives:, Acute back and neck strains are very common. In addition to administering analgesics, these strains are often treated with either heat or cold packs. The objective of this study was to compare the analgesic efficacy of heat and cold in relieving pain from back and neck strains. The authors hypothesized that pain relief would not differ between hot and cold packs. Methods:, This was a randomized, controlled trial conducted at a university-based emergency department (ED) with an annual census of 90,000 visits. ED patients >18 years old with acute back or neck strains were eligible for inclusion. All patients received 400 mg of ibuprofen orally and then were randomized to 30 minutes of heating pad or cold pack applied to the strained area. Outcomes of interest were pain severity before and after pack application on a validated 100-mm visual analog scale (VAS) from 0 (no pain) to 100 (worst pain), percentage of patients requiring rescue analgesia, subjective report of pain relief on a verbal rating scale (VRS), and future desire for similar packs. Outcomes were compared with t-tests and chi-square tests. A sample of 60 patients had 80% power to detect a 15-mm difference in pain scores. Results:, Sixty patients were randomized to heat (n = 31) or cold (n = 29) therapy. Mean (±standard deviation [SD]) age was 37.8 (±14.7) years, 51.6% were female, and 66.7% were white. Groups were similar in baseline patient and pain characteristics. There were no differences between the heat and cold groups in the severity of pain before (75 mm [95% CI = 66 to 83] vs. 72 mm [95% CI = 65 to 78]; p = 0.56) or after (66 mm [95% CI = 57 to 75] vs. 64 mm [95% CI = 56 to 73]; p = 0.75) therapy. Pain was rated better or much better in 16/31 (51.6%) and 18/29 (62.1%) patients in the heat and cold groups, respectively (p = 0.27). There were no between-group differences in the desire for and administration of additional analgesia. Twenty-five of 31 (80.6%) patients in the heat group and 22 of 29 (75.9%) patients in the cold group would use the same therapy if injured in the future (p = 0.65). Conclusions:, The addition of a 30-minute topical application of a heating pad or cold pack to ibuprofen therapy for the treatment of acute neck or back strain results in a mild yet similar improvement in the pain severity. However, it is possible that pain relief is mainly the result of ibuprofen therapy. Choice of heat or cold therapy should be based on patient and practitioner preferences and availability. ACADEMIC EMERGENCY MEDICINE 2010; 17:484,489 © 2010 by the Society for Academic Emergency Medicine [source] Lessons in Warmth, Heat, and LightACADEMIC EMERGENCY MEDICINE, Issue 4 2004Michael D. Burg MD No abstract is available for this article. [source] Development of a Novel Animal Burn Model Using Radiant Heat in Rats and SwineACADEMIC EMERGENCY MEDICINE, Issue 5 2010Reuven Gurfinkel MD Abstract Objectives:, The objective was to develop a novel animal model of burns in rats and pigs. Methods:, The model uses heat that is delivered via a radiant heater with an opening of 5 cm by 5 cm, set at 400°C, for 20 seconds. An advantage of this model is that the heating source does not come into direct contact with the animal, and the heat dispersion surrounding its center is very constant. The device was evaluated in 40 rats and seven pigs. With rats, three to four burns were created on each rat, resulting in a burn covering a total body surface area of 30% to 50%. In pigs, 16 burns were created on each animal. Results:, In rats, infliction of burns resulted in mortality rates of 0%,50% depending on the size of the burns and the rats. In pigs, the burns reepithelialized within approximately 3 weeks and resulted in hourglass contracted scars in two of three burns within 1 month. Conclusions:, The authors describe a novel animal burn model that utilizes radiant heat to create consistent burns that maximizes safety to the investigators and animals. ACADEMIC EMERGENCY MEDICINE 2010; 17:514,520 © 2010 by the Society for Academic Emergency Medicine [source] Interactions between salivary Bifidobacterium adolescentis and other oral bacteria: in vitro coaggregation and coadhesion assaysFEMS MICROBIOLOGY LETTERS, Issue 2 2008Seiji Nagaoka Abstract Coaggregation assays were performed to investigate interactions between oral Bifidobacterium adolescentis and other oral bacterial species. Bifidobacterium adolescentis OLB6410 isolated from the saliva of healthy humans did not coaggregate with Actinomyces naeslundii JCM8350, Streptococcus mitis OLS3293, Streptococcus sanguinis JCM5708, Veillonella parvula ATCC17745 or Porphyromonas gingivalis OB7124, but it did coaggregate with Fusobacterium nucleatum JCM8532. Subsequent examination of biofilm formation on saliva-coated hydroxyapatite discs using FISH revealed that B. adolescentis OLB6410 could not directly adhere to the coated discs. It did, however, adhere to biofilms of A. naeslundii, V. parvula, and F. nucleatum, although it did not coaggregate with A. naeslundii nor with V. parvula. These results suggest that the adhesion of B. adolescentis to tooth surfaces is mediated by other oral bacteria. Heat- or proteinase K-treated F. nucleatum could not coaggregate with B. adolescentis. Similarly, the coaggregation and coadhesion of proteinase K-treated B. adolescentis were strongly inhibited. It is therefore probable that proteinaceous factors on the cellular surface of B. adolescentis and F. nucleatum are involved in their interaction. The data presented in this study add to our understanding of bifidobacterial colonization in the human oral cavity. [source] Heat and mass transfer phenomena in magnetic fluidsGAMM - MITTEILUNGEN, Issue 1 2007Th. Völker Abstract In this article the influence of a magnetic field on heat and mass transport phenomena in magnetic fluids (ferrofluids) will be discussed. The first section is dealing with a magnetically driven convection, the so called thermomagnetic convection while in the second section the influence of a temperature gradient on the mass transport, the Soret effect in ferrofluids, is reviewed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spring temperatures in the Sagehen Basin, Sierra Nevada, CA: implications for heat flow and groundwater circulationGEOFLUIDS (ELECTRONIC), Issue 3 2009MARIA BRUMM Abstract Heat flow in the Sierra Nevada, CA, is low despite its young geologic age. We investigate the possibility that advective heat transport by groundwater flow leads to an underestimate of heat flow in the Sierras based purely on borehole measurements. Using temperature and discharge measurements at springs in Sagehen Basin, we find that groundwater removes the equivalent of approximately 20,40 mW m,2 of geothermal heat from the basin. This is comparable with other heat flow measurements in the region and indicates that, in this basin, at least, groundwater does transport a significant amount of geothermal heat within the basin. Additionally, we use estimates of the mean residence time of water discharged at the springs along with hourly temperature records in springs to provide constraints on groundwater flow depths within the basin. An analytical model based on these constraints indicates that the heat removed by groundwater may represent 20% to >90% of the total heat flow in the basin. Without better constraints on the regional hydrogeology and the depth of circulation, we cannot determine whether the heat discharged at the springs represents a change in the mode of heat transfer, i.e. from conduction to advection at shallow depths (<100 m) or whether this is a component of heat transfer that should be added to measured conductive values. If the latter is true, and Sagehen Basin is representative of the Sierras, basal heat flow in the Sierra Nevada may be higher than previously thought. [source] Is advective heat transport significant at the Dead Sea basin?GEOFLUIDS (ELECTRONIC), Issue 3 2007E. SHALEV Abstract An understanding of heat flux is a necessary component in reconstructing tectonic, seismic, and hydrologic models of the Dead Sea basin. Heat may be transferred by both conduction and advection by groundwater. Although the conductive heat flux in Israel has been extensively measured to be approximately 40 mW m,2, there is still a debate about the total heat flux. Recently, the discharge of hot springs along the western Dead Sea shore has been determined to be 107 m3 year,1. Simple calculations show that the heat discharged by groundwater at these hot springs is of the same order of magnitude as the measured conductive heat flux in deep boreholes. Therefore the total heat flux could be significantly higher than 40 mW m,2. However, results of numerical modeling show that the current hot-spring heat discharge is two orders of magnitude greater than that predicted for steady-state conditions and can be explained by the rapid recession of the Dead Sea. [source] A thermochemical boundary layer at the base of Earth's outer core and independent estimate of core heat fluxGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2008David Gubbins SUMMARY Recent seismological observations suggest the existence of a ,150-km-thick density-stratified layer with a P -wave velocity gradient that differs slightly from PREM. Such a structure can only be caused by a compositional gradient, effects of a slurry or temperature being too small and probably the wrong sign. We propose a stably stratified, variable concentration layer on the liquidus. Heat is transported by conduction down the liquidus while the light and heavy components migrate through the layer by a process akin to zone refining, similar to the one originally proposed by Braginsky. The layer remains static in a frame of reference moving upwards with the expanding inner core boundary. We determine the gradient using estimates of co, the concentration in the main body of the outer core, and cb, the concentration of the liquid at the inner core boundary. We determine the depression of the melting point and concentrations using ideal solution theory and seismologically determined density jumps at the inner core boundary. We suppose that co determines ,,mod, the jump from normal mode eigenfrequencies that have long resolution lengths straddling the entire layer, and that cb determines ,,bod, the jump determined from body waves, which have fine resolution. A simple calculation then yields the seismic, temperature, and concentration profiles within the layer. Comparison with the distance to the C-cusp of PKP and normal mode eigenfrequencies constrain the model. We explore a wide range of possible input parameters; many fail to predict sensible seismic properties and heat fluxes. A model with ,,mod= 0.8 gm cc,1, ,,bod= 0.6 gm cc,1, and layer thickness 200 km is consistent with the seismic observations and can power the geodynamo with a reasonable inner core heat flux of ,2 TW and nominal inner core age of ,1 Ga. It is quite remarkable and encouraging that a model based on direct seismic observations and simple chemistry can predict heat fluxes that are comparable with those derived from recent core thermal history calculations. The model also provides plausible explanations of the observed seismic layer and accounts for the discrepancy between estimates of the inner core density jumps derived from body waves and normal modes. [source] Heat and fluid flow characteristics inside differentially heated square enclosures with single and multiple sliding wallsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 7 2009E.M. Wahba Abstract Fluid flow and heat transfer characteristics of differentially heated lid driven cavities are numerically modeled and analyzed in the present study. One-, two-, and four-sided lid driven cavity configurations are considered with the vertical walls being maintained at different temperatures and the horizontal walls being thermally insulated. Eight different cavity configurations are considered depending on the direction of wall motion. The Prandtl number Pr is taken to be 0.7, the Grashof number is taken to be 104, while two values for the Richardson number Ri are considered, 0.1 and 10. It is found that both the Richardson number and the cavity configuration affect the heat and fluid flow characteristics in the cavity. It is concluded that for Ri=0.1, a four-sided driven cavity configuration with all walls rotating in the same direction would triple the value of the average Nusselt number at the cold wall when compared to a one-sided driven cavity configuration. However, for Ri=10, the cavity configuration has minimal effect and all eight cases result in an average Nusselt number value at the cold wall ranging between 1.3 and 1.9. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/htj.20264 [source] Evaluation of canal filling after using two warm vertical gutta-percha compaction techniques in vivo: a preliminary studyINTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2006M. Venturi Abstract Aim, To evaluate the quality of root canal filling when comparing two warm gutta-percha filling techniques in vivo. Methodology, Human teeth were randomly divided into two equal groups, with 30 canals each. The root canals were shaped by hand and ProFile 0.04 rotary instruments to size 20,40 at the end-point and then filled with gutta-percha cones and AH-Plus. In group A, a traditional warm vertical compaction technique was performed using the Touch'n Heat, and back-filling with the Obtura II. In group B, a modified warm vertical compaction technique was used: small amounts of gutta-percha were removed, and the remaining most apical 3 mm were compacted with a 1 mm movement; then thermomechanical back-filling was performed. The teeth were extracted, stored in dye, cleared, and the distance between the apex and apical limit of the filling, linear dye penetration, and voids were measured from the buccal, lingual, mesial and distal perspective. The homogeneity of variance and means was verified using Levene's test and t -test. anova and Dunnett post hoc test were used to establish the significance and to analyse the effects through multiple comparisons. Results, Compared with the specimens of group A, the specimens of group B exhibited less mean linear dye penetration (P < 0.05), smaller void length (P , 0.05) and maximal width (P , 0.05) when examined in all four views, and a more precise filling when viewed from the buccal aspect (P < 0.05). Conclusions, The modified warm vertical compaction technique with apical back-filling produced a more effective and precise three-dimensional filling. [source] Numerical simulation of turbulent impinging jet on a rotating diskINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2007A. Abdel-Fattah, Article first published online: 25 OCT 200 Abstract The calculations of quasi-three-dimensional momentum equations were carried out to study the influence of wall rotation on the characteristics of an impinging jet. The pressure coefficient, the mean velocity distributions and the components of Reynolds stress are calculated. The flow is assumed to be steady, incompressible and turbulent. The finite volume scheme is used to solve the continuity equation, momentum equations and k,, model equations. The flow characteristics were studied by varying rotation speed , for 0,,,167.6 rad/s, the distance from nozzle to disk (H/d) was (3, 5, 8 and 10) and the Reynolds number Re base on VJ and d was 1.45 × 104. The results showed that, the radial velocity and turbulence intensity increase by increasing the rotation speed and decrease in the impingement zone as nozzle to disk spacing increases. When the centrifugal force increases, the radial normal stresses and shear stresses increase. The location of maximum radial velocity decreases as the local velocity ratio (,) increases. The pressure coefficient depends on the centrifugal force and it decreases as the distance from nozzle to plate increases. In impingement zone and radial wall jet, the spread of flow increases as the angular velocity decreases The numerical results give good agreement with the experiment data of Minagawa and Obi (Int. J. of Heat and Fluid Flow 2004; 25:759,766). Copyright © 2006 John Wiley & Sons, Ltd. [source] Head lice on pillows, and strategies to make a small risk even lessINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 8 2003Rick Speare Background Due to a lack of evidence, controversy exists about the role of bedding in the transmission of head lice. Aims To determine the proportion of the head lice population found on pillowcases of people with head lice, and to test strategies available to householders to kill head lice on pillowcases. Methods To assess the incidence of head lice on pillowcases, people with active pediculosis had their head lice collected and counted and the pillowcase they had used the night before examined for head lice. To test strategies to kill head lice on pillowcases, live head lice were experimentally placed in miniature pillowcases, and the cases were subjected to a hot wash, a cold wash, hot dryer, and hanging out to dry on an outdoor clothes line. Results Forty-eight people and their pillowcases were recruited from Townsville, Qld, Australia (dry tropics). One thousand, eight hundred and forty-five lice were collected from their heads to give an average and median intensity of infection of 38.4 and 21 lice, respectively. Two of the 48 pillowcases contained live lice, one nymph on each, 2 h and 9 h after the pillowcases had been removed from the bed. Another pillowcase contained a dehydrated nymph. The incidence of live lice on pillowcases was 4.2% per night and the proportion of the head louse population on the pillowcases was 0.11%. Heat (hot wash and hot clothes dryer) killed head lice experimentally placed in pillowcases. Cold wash and hanging pillowcases out to dry did not kill head lice. Conclusions Head lice transfer to pillowcases at night, but the incidence is low. Pillowcases pose a risk for re-infection with head lice, but the risk is low, and changing the pillowcase is a reasonably cost-efficient strategy to minimize this risk. Lice on pillowcases can be killed by heating the pillowcase by immersion in water at > 60 °C, by a hot wash, or by 15 min in a hot clothes dryer. [source] Response of Oryzacystatin I Transformed Tobacco Plants to Drought, Heat and Light StressJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2010K. Demirevska Abstract Transformed tobacco plants expressing a rice cysteine proteinase inhibitor (OC-I) and non-transformed plants were grown in a controlled environment and subjected to various stresses. Two-month-old transformed and non-transformed plants were exposed for 5 days to drought conditions by withholding watering. High temperature (40 °C) was applied additionally at day 6th for 5 h either individually or in combination with drought. All stress treatments were applied under low (150 ,mol m,2 s,1 PPFD) and high light intensity (HL) of 1000 ,mol m,2 s,1 PPFD to determine if OC-I expression might provide protection under combination of stresses usually existing in nature. Drought stress led to diminution in leaf relative water content, photosynthesis inhibition, decrease in chlorophyll content and accumulation of malondialdehyde and proline. Heat stress alone did not affect the plants significantly, but intensified the effect of drought stress. HL intensity further increased the proline content. OC-I transformed plants grown under low light intensity had significantly higher total superoxide dismutase and guaiacol peroxidase activities as well as their isoforms than non-transformed control plants under non-stress and stress conditions. Catalase activity was not highly affected by OC-I expression. Results indicate that OC-I expression in tobacco plants provides protection of the antioxidative enzymes superoxide dismutase and guaiacol peroxidise under both non-stress and stress conditions. [source] Combined effect of mild heat and acetic acid treatment for inactivating Escherichia coli O157:H7, Listeria monocytogenes and Salmonella typhimurium in an asparagus pureeJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2006J.-H. Shin Abstract Aims:, This study was conducted to validate combined heat and acid treatments for inactivating Escherichia coli O157:H7, Listeria monocytogenes and Salmonella typhimurium in an acidified brine containing, or pickled, asparagus model food. Methods and Results:, A mixture of three strains of E. coli O157:H7, L. monocytogenes and S. typhimurium were inoculated onto pickled asparagus samples. Combinations of various concentrations of acetic acid [0%, 0·25%, 0·5%, 0·75%, 1%, 1·5% and 2% (v/v)] and various temperatures (40°C, 50°C, 60°C and 75°C) were investigated. Following treatment, asparagus samples were stored at room temperature and enumerated at 0, 0·5, 1, 2 and 3 days. Heat and acetic acid treatments were synergistic. The inhibitory effects of these combined treatments on the tested foodborne pathogens were also effective during storage. Loss of green colour in the pickled asparagus significantly increased with increasing concentrations of acetic acid. Conclusions:, Using a combination of mild heat and acetic acid treatments can successfully control E. coli O157:H7, L. monocytogenes and S. typhimurium in pickled asparagus, combinations of heat and acid are synergistic and effective treatments can be selected to reduce adverse effect on colour which occur during product storage. Significance and Impact of the Study:, Mild heating plus acetic acid treatment are synergistic, so combined treatments can be developed, which would lower the temperature and amount of acetic acid required for minimally processed vegetables while maintaining pathogen control. [source] Interactions between Saccharomyces cerevisiae and malolactic bacteria: preliminary characterization of a yeast proteinaceous compound(s) active against Oenococcus oeniJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2005F. Comitini Abstract Aims:, To investigate the occurrence and extent of Saccharomyces cerevisiae and Oenococcus oeni interactions. Methods and Results:, Interactions between S. cerevisiae and O. oeni were investigated by double-layer and well-plate assays showing the occurrence of specific interactions for each yeast,malolactic bacteria (MLB) coupling. Heat and protease treatments of synthetic grape juice fermented by the S. cerevisiae strain F63 indicated that the inhibitory activity exerted by this yeast on O. oeni is due to a proteinaceous factor(s) which exerts either bacteriostatic or bactericidal effect depending on concentration and affects malolactic fermentation in natural grape juice and wine. Conclusions:, A proteinaceous factor(s) produced by a S. cerevisiae wine strain able to inhibit O. oeni growth and malic acid fermentation was characterized. Significance and Impact of the Study:, The individuation, characterization and exploitation of yeast proteinaceous factor(s) exerting inhibitory activity on MLB may offer new opportunities for the management of malolactic fermentation. [source] Atrial Fibrillation: Much Heat, A Little LightJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2006F.C.S.A.N.Z., F.R.A.C.P., MARK A. McGUIRE M.B.B.S., Ph.D. [source] A NUMERICAL APPROACH WITH VARIABLE TEMPERATURE BOUNDARY CONDITIONS TO DETERMINE THE EFFECTIVE HEAT TRANSFER COEFFICIENT VALUES DURING BAKING OF COOKIESJOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2006EREN DEMIRKOL ABSTRACT The increasing trade of ready-to-eat foods such as cookies highlights an interest in quality defects during baking. Heat (h and thermal diffusivity) and mass (mass transfer and diffusion coefficients) transfer parameters are significant parameters affecting the quality changes. Therefore, it is important to determine these parameters for modeling and process optimization studies. Among these, the h is important, revealing the relationship between the heating medium and product surface. As baking involves a simultaneous heat and mass transfer involving moisture diffusion and heat conduction inside and convective heat and mass transfer outside, a lumped system method may not be an accurate choice to determine the h value. Changes in the product volume and contact heating from bottom of the product also bring extra challenges to the determination of h. Therefore, the objective of this study was to use realistic approaches including simultaneous heat and mass transfer to determine the changes in h. The heffvalues for the bottom and top surface of the cookies were then determined, applying a numerical procedure where the surface temperature changes were the boundary conditions with evaporation on the surface. The hband ht values increased with baking temperature and varied with baking time. The results of this study showed that evaporative mass flux for the top surface, heat flux for the bottom surface and the product's volume changes were significant in the variation of h values. [source] MODELING OF HEAT AND MASS TRANSFER DURING BAKING OF BISCUITSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2004MARIA ELENA SOSA-MORALES ABSTRACT Precooked biscuits (7 cm diameter × 2 cm thickness), preserved by freezing, were evaluated in a regional bakery. Heat and mass transfer during these processes and through the final baking were studied. Precooking was conducted at 180C for 18 min; convection and conduction were the predominant phenomena for heat transfer, with an ,, = 1.71 × 10,7 m2/s. Diffusion mechanism adequately modeled (r2 = 0.94, PEM < 2.5%) the moisture loss during cooking stage, with a D = 1.04 × 10,6 m2/s. The freezing point obtained inside a tunnel freezer (forced air at ,,40C), was , 6.73C, consistent with the predicted value. Volume changes were minimal during frozen storage because of high fat content and few variations in the freezer temperature. Final baking in conventional gas and microwave ovens were compared. Higher moisture loss and minimal color change occurred in the microwave baking. Instrumental texture of both final treatments were significantly different, in contrary to sensory evaluation (, = 0.05). The methods produced a good choice for product commercialization after baking. [source] Sporulation and Germination Gene Expression Analysis of Bacillus anthracis Sterne Spores in Skim Milk under Heat and Different Intervention TechniquesJOURNAL OF FOOD SCIENCE, Issue 3 2009Y. Liu ABSTRACT:, To investigate how B. anthracis Sterne spores survive in milk under heat (80 °C, 10 min), pasteurization (72 °C, 15 s), microfiltration, and pasteurization and microfiltration, the expression levels of genes related to sporulation and germination were tested using real-time PCR assays. Twenty-seven sporulation- and germination-related genes were selected for the target genes. Our results demonstrated that gene expression levels were altered by heat and microfiltration whereas the pasteurization and pasteurization and microfiltration resulted in less alteration of gene expression. Heat activated and inhibited both sporulation- and germination-related genes, suggesting that bacterial spores underwent different molecular mechanism for heat treatments. Our results may provide some insight into the molecular mechanisms of spore survival in response to heat treatment and different intervention strategies used to treat fluid skim milk. [source] Heat Intensity and Warmed-over Flavor in Precooked Chicken Patties Formulated at 3 Fat Levels and 3 Pepper LevelsJOURNAL OF FOOD SCIENCE, Issue 9 2005Margaret E. Emrick ABSTRACT: Heat intensity and warmed-over flavor (WOF) were evaluated to determine the effects the composition of precooked, chopped, and formed chicken patties would impart on the perception of red pepper heat and the development of oxidation. Patties were formulated at 5%, 7%, and 9% fat with marinade formulated at 0%, 0.2%, and 0.4% pepper. A trained sensory panel assessed the heat intensity over 3 min using time intensity evaluation. Heat and WOF intensities of the patties were measured 5 times over a 9-wk storage period. As fat level increased, total time intensity and time to maximum heat intensity increased. Patties formulated at 7% and 9% fat were perceived to be more intense in heat than the 5% fat patties. Patties formulated at 0.2% and 0.4% pepper had less intense WOF than patties with 0% pepper level. Chemical measurement of oxidation (thiobarbituric acid numbers) indicated that increasing pepper content decreased malonaldehyde content. Incorporation of pepper into a chopped and formed meat product requires a higher pepper content at lower fat levels to impart the same level of heat intensity as in patties of higher fat level. Increasing the pepper content also will aid in decreasing production of malonaldehyde in a precooked meat product, thereby reducing the intensity of warmed-over flavor as perceived by the consumer. [source] Heat and mass transfer during microwave-convective dryingAICHE JOURNAL, Issue 1 2010Stefan J. Kowalski Abstract The article presents a mathematical model of drying that describes the kinetics of combined microwave-convective drying for the process as a whole. Based on this model, the drying curves and the temperature evolutions of the drying body were constructed by a number of computer-simulated drying programs, which were chosen to follow the respective experimental processes carried out on a cylindrical sample made of kaolin. The experimental data allowed both the estimate of material coefficients arising in the model and the validation of the theory. A very satisfactory correlation of the theoretical predictions with the experimental data is found. The main novelty of this article is the mathematically complete drying model that describes all periods of the microwave-convective drying process. Application of such a complete model is necessary if we want to optimize drying processes with respect to drying time and consumption of energy via computer simulations. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The role of viscous heating in Barrovian metamorphism of collisional orogens: thermomechanical models and application to the Lepontine Dome in the Central AlpsJOURNAL OF METAMORPHIC GEOLOGY, Issue 2 2005J.-P. BURG Abstract Thermal models for Barrovian metamorphism driven by doubling the thickness of the radiogenic crust typically meet difficulty in accounting for the observed peak metamorphic temperature conditions. This difficulty suggests that there is an additional component in the thermal budget of many collisional orogens. Theoretical and geological considerations suggest that viscous heating is a cumulative process that may explain the heat deficit in collision orogens. The results of 2D numerical modelling of continental collision involving subduction of the lithospheric mantle demonstrate that geologically plausible stresses and strain rates may result in orogen-scale viscous heat production of 0.1 to >1 ,W m,3, which is comparable to or even exceeds bulk radiogenic heat production within the crust. Thermally induced buoyancy is responsible for crustal upwelling in large domes with metamorphic temperatures up to 200 °C higher than regional background temperatures. Heat is mostly generated within the uppermost mantle, because of large stresses in the highly viscous rocks deforming there. This thermal energy may be transferred to the overlying crust either in the form of enhanced heat flow, or through magmatism that brings heat into the crust advectively. The amplitude of orogenic heating varies with time, with both the amplitude and time-span depending strongly on the coupling between heat production, viscosity and collision strain rate. It is argued that geologically relevant figures are applicable to metamorphic domes such as the Lepontine Dome in the Central Alps. We conclude that deformation-generated viscous dissipation is an important heat source during collisional orogeny and that high metamorphic temperatures as in Barrovian type metamorphism are inherent to deforming crustal regions. [source] P,T modelling of the andalusite,kyanite,andalusite sequence and related assemblages in high-Al graphitic pelites.JOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2001Prograde, retrograde paths in a late kyanite belt in the Variscan Iberia Abstract The exceptional andalusite,kyanite,andalusite sequence occurs in Al-rich graphitic slates in a narrow pelite belt on the hangingwall of a ductile normal fault in NW Variscan Iberia. Early chiastolite is replaced by Ky,Ms,Pg aggregates, which are overgrown by pleochroic andalusite near granites intruded along the fault. Slates plot in AKFM above the chloritoid-chlorite tie-line. Their P,T grids are modelled with Thermocalc v2.7 and the 1998 databases in the NaKFMASH and KFMASH systems. The univariant reaction Ctd + And/Ky = St + Chl + Qtz + H2O ends at progressively lower pressure as F/FM increases and A/AFM decreases, shrinking the assemblage Cld,Ky,Chl, and opening a chlorite-free Cld,Ky trivariant field on the low temperature reaction side. This modelling matches the observed absence of chlorite in high F/FM rocks, which is restricted to low pressure in the andalusite stability field. The P,T path deduced from modelling shows a first prograde event in the andalusite field followed by retrogression into the kyanite field, most likely coupled with a slight pressure increase. The final prograde evolution into the andalusite field can be explained by two different prograde paths. Granite intrusion caused the first prograde part of the path with andalusite growth. The subsequent thermal relaxation, together with aH2O decrease, generated the retrograde andalusite,kyanite transformation, plus chlorite consumption and chloritoid growth. This transformation could have been related to folding in the beginning, and aided later by downthrowing due to normal faulting. Heat supplied by syntectonic granite intrusion explains the isobaric part of the path in the late stages of evolution, causing the prograde andalusite growth after the assemblage St,Ky,Chl. Near postectonic granites, a prograde path with pressure decrease originated the assemblage St,And,Chl. [source] Evolution of the Pan-African Wadi Haimur metamorphic sole, Eastern Desert, EgyptJOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2000H. Abd El-Naby By comparison with the general features of metamorphic soles (e.g. vertical and lateral extension, metamorphic grade and diagnostic mineral parageneses, deformation and dominant rock types), it is inferred that the amphibolites, metagabbros and hornblendites of the Wadi Um Ghalaga,Wadi Haimur area in the southern part of the Eastern Desert of Egypt represent the metamorphic sole of the Wadi Haimur ophiolite belt. The overlying ultramafic rocks represent overthrusted mantle peridotite. Mineral compositions and thermobarometric studies indicate that the rocks of the metamorphic sole record metamorphic conditions typical of such an environment. The highest P,T conditions (c. 700 °C and 6.5,8.5 kbar) are preserved in clinopyroxene amphibolites and garnet amphibolites from the top of the metamorphic sole, which is exposed in the southern part of the study area. The massive amphibolites and metagabbros further north (Wadi Haimur) represent the basal parts of the sole and show the lowest P,T conditions (450,620 °C and 4.7,7.8 kbar). The sole is the product of dynamothermal metamorphism associated with the tectonic displacement of ultramafic rocks. Heat was derived mainly from the hot overlying mantle peridotites, and an inverted P,T gradient was caused by dynamic shearing during ophiolite emplacement. Sm/Nd dating of whole-rock,metamorphic mineral pairs yields similar ages of c. 630 Ma for clinopyroxene and hornblende, which is interpreted as a lower age limit for ophiolite formation and an upper age limit for metamorphism. A younger Sm/Nd age for a garnet-bearing rock (c. 590 Ma) is interpreted as reflecting a meaningful cooling age close to the metamorphic peak. Hornblende K/Ar ages in the range 570,550 Ma may reflect thermal events during late orogenic granite magmatism. [source] | |||||||||||||||||||||||||||||||||||||||||||