914 resultados para Cold Shock


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Abstract The aim of this study was to evaluate the microbiological and sensory quality of the Jambu (Acmella oleracea L.) in natura and dried by cold air, and the determination of its drying curve. The microbiological analysis were performed to Salmonella spp, the coagulase-positive Staphylococcus, and coliforms in the both Jambu samples, at 45 °C. Tacacá, the typical food dish of Pará state, Brazil, has showed good consumer global acceptance in the sensory evaluation of Jambu in natura (score of 8.00 ± 1.46) and dried (score of 8.67 ± 0.66). Both samples, Jambu in natura and dried by cold air, were by the current legislation regarding the microbiological aspects, this is the absence of Salmonella spp, coagulase-positive Staphylococcus <1×101 CFU/g, and coliforms <3 MPN/g, at 45 °C. Thus, considering sensory and health aspects, the commercialization of dried Jambu becomes viable, facilitating its transportation and handling, as well as for reducing its vegetable mass.

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The supersweet (Sh2) corn seeds have a thin tegument and an irregular shape, which hinder the sowing procedure. As a function of those factors, the significance of using the pelleting process to improve sowing and standardize the stand of plants in the field without the need of thinning within the row is emphasized. Although this technique has already been known for many years, little has been studied on the effect of such procedure on the plantability and on the moisture content of the supersweet corn seeds. Therefore, this research work aimed at evaluating the effects of pelleting on the moisture content of the seeds along the storing process, on the occurrence of gaps on seed deposition and on the dropping of double seeds, with the aid of a testing seeder. Other physical attributes of seeds and pellets were also evaluated through tests of fragmentation, screen retention, mass of a thousand seeds and apparent volume. Results have shown an increase on the mass and on the volume of the pelleted seeds that presented highly resistance to cracks and breaking. The pelleting was efficient on the reduction of gaps and on the deposition of double seeds at sowing, thus providing highly satisfactory results for these attributes. An increase on the seed moisture content was also observed as a function of storage with a significant reduction on this factor after the pelleting procedure. Results allow concluding that the pelleting process reduces seed moisture content and improves plantability, positively affecting the efficiency of the sowing process.

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The aim of this thesis was to examine efficiency of freeze crystallization and eutectic freeze crystallization in purification of wastewater by imitating natural freezing. In addition, a mathematic model based on heat transfer to determine ice thickness and ice growth rate was examined. Also, the amount of sodium sulfate crystallized at the eutectic point was under investigation. In literature part, advantages and applications of the freeze crystallization are discussed, and possibility to apply it in Northern hemisphere winter weather conditions is under study. Furthermore, main sources of sodium sulfate from Finnish industries are described. The experiments were carried out in modified chest freezer, where a fan was placed in order to obtain laminar air flow inside. Picolog PT-104 data logger was used to monitor temperature changes in the salt-water solution, and constant temperature was maintained in the crystallizer with Lauda RP 850 thermostat. The impurity of formed ice layer was determined by weighing ice samples after experiment and again after 24 hours drying to full dryness in oven. Volume of salt-water solution was also measured after experiment. The highest purity of formed ice layer was obtained with small temperature difference and with long freezing time. On the other hand, the amount of crystallized sodium sulfate was its greatest with long freezing time and higher temperature difference. The results obtained by the mathematic model and empirical results did not differ significantly in most of the experiments. However, the difference increased when salt-water mixture reached its eutectic point, leading to simultaneous ice and salt crystallization. Eutectic point was reached only with the highest salt concentration with one exception. In these cases, calculated values were in many cases greater than the experimental ones. In winter weather conditions freeze crystallization is cost-effective wastewater treatment method and rather simple. Nonetheless, the efficiency and separation rate are strongly depended on ambient temperature and its changes

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The study centers on the power of Right-Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO) as predictors of prejudice against stereotypical and nonstereotypical homosexuals under the threat of death and the threat of uncertainty. Right-wing authoritarianism (RWA) is an individual difference variable that measures the tendency for individuals to unquestionably follow those perceived to be authorities. Social Dominance Orientation (SDO) is an individual difference variable that measures the degree to which an individual prefers inequality among social groups. The RWA and SDO Scales are considered to be two of the strongest predictors of prejudice, such as prejudice against homosexuals. The study focuses on the unique predictive power of these two variables in predicting prejudice against homosexuals. The study also examines the role of situational threat in prejudice, specifically the threat of death (mortality salience) and the threat of uncertainty (uncertainty salience). Competing predictions from theories involving the threat of death (Terror Management Theory) and the threat of uncertainty (Uncertainty Management Theory) are also tested. The preference for expected information in the form of stereotypes concerning male homosexuals (that is, a stereotypical or non-stereotypical homosexual) were tested. The difference between the predictive power ofRWA and SDO was examined by measuring how these variables predict liking of a stereotypical or non-stereotypical homosexual under the threat of death, the threat of uncertainty, or a control condition. Along with completing a measure for RWA and a measure for SDO, participants were asked to think of their own death, of their being uncertain or about watching television then were asked to read about a week in the life of either a stereotypical or non-stereotypical male homosexual. Participants were then asked to evaluate the individual and his essay. Based on the participants' evaluations, results from 180 heterosexual university students show that RWA and SDO are strong predictors for disliking of a stereotypical homosexual under the threat of uncertainty and disliking of a non-stereotypical homosexual under the threat of death. Furthermore, however, results show that RWA is a particularly strong predictor of disliking of a stereotypical homosexual under the threat of uncertainty, whereas SDO is an exceptionally strong predictor of disliking of the non-stereotypical homosexual under the threat of death. This further adds to the notion that RWA and SDO are indeed unique predictors of prejudice. Implications are also explored, including the fact that the study simuhaneously examined the role of individual difference variables and situational threat variables, as well as exploratory analysis on Dominating Authoritarians.

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This study examined the interactions between the reproductive status and the thermoregulatory responses during exercise in the cold in girls involved in competitive sports. Four girls with established menstrual cycles comprised the eumenorrheic menarcheal group (EM) and 5 non-menstruating girls comprised the pre-menarcheal group (PM). During the first visit maximal oxygen consumption, height, weight and percent body fat (%BF) were measured. The second visit involved: a determination of metabolic rate in thermoneutrality (21°C) involving 10-min rest and 20-min cycling (30% of VCL max), and a cold stress test (5°C, 40% humidity, <0.3 m/s air velocity) involving 20-min rest and 40-min cycling (30% of VCL max.). Subjects in the EM group were tested twice in the chamber during the follicular and luteal phases. Pre-menarcheal subjects were found to have significantly (p<0.05) lower core temperatures during the final stages of cold exposure. Overall, body fat was not significantly correlated with core temperature in the cold, however there was a significant surface-to-mass ratio difference between the groups. While in the follicular phase, EM girls had a higher core temperature during cold exposure. Therefore, reproductive hormonal status seems to be an important factor in terms of cold tolerance in females during adolescence.

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Low temperature (77K) linear dichroism spectroscopy was used to characterize pigment orientation changes accompanying the light state transition in the cyanobacterium, Synechococcus sp. pee 6301, and cold-hardening in winter rye (Secale cereale L. cv. Puma). Samples were oriented for spectroscopy using the gel squeezing method (Abdourakhmanov et aI., 1979) and brought to 77K in liquid nitrogen. The linear dichroism (LD) spectra of Synechococcus 6301 phycobilisome/thylakoid membrane fragments cross-linked in light state 1 and light state 2 with glutaraldehyde showed differences in both chlorophyll a and phycobilin orientation. A decrease in the relative amplitude of the 681nm chlorophyll a positive LD peak was observed in membrane fragments in state 2. Reorientation of the phycobilisome (PBS) during the transition to state 2 resulted in an increase in core allophycocyanin absorption parallel to the membrane, and a decrease in rod phycocyanin parallel absorption. This result supports the "spillover" and "PBS detachment" models of the light state transition in PBS-containing organisms, but not the "mobile PBS" model. A model was proposed for PBS reorientation upon transition to state 2, consisting of a tilt in the antenna complex with respect to the membrane plane. Linear dichroism spectra of PBS/thylakoid fragments from the red alga, Porphyridium cruentum, grown in green light (containing relatively more PSI) and red light (containing relatively more PSll) were compared to identify chlorophyll a absorption bands associated with each photosystem. Spectra from red light - grown samples had a larger positive LD signal on the short wavelength side of the 686nm chlorophyll a peak than those from green light - grown fragments. These results support the identification of the difference in linear dichroism seen at 681nm in Synechococcus spectra as a reorientation of PSll chromophores. Linear dichroism spectra were taken of thylakoid membranes isolated from winter rye grown at 20°C (non-hardened) and 5°C (cold-hardened). Differences were seen in the orientation of chlorophyll b relative to chlorophyll a. An increase in parallel absorption was identified at the long-wavelength chlorophyll a absorption peak, along with a decrease in parallel absorption from chlorophyll b chromophores. The same changes in relative pigment orientation were seen in the LD of isolated hardened and non-hardened light-harvesting antenna complexes (LHCII). It was concluded that orientational differences in LHCII pigments were responsible for thylakoid LD differences. Changes in pigment orientation, along with differences observed in long-wavelength absorption and in the overall magnitude of LD in hardened and non-hardened complexes, could be explained by the higher LHCII monomer:oligomer ratio in hardened rye (Huner et ai., 1987) if differences in this ratio affect differential light scattering properties, or fluctuation of chromophore orientation in the isolated LHCII sample.

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Several stresses to tissues including hyperthermia, ischemia, mechanical trauma and heavy metals have been demonstrated to affect the regulation of a subset of the family of heat shock proteins of70kOa (hsp70). In several organisms following some of these traumas, the levels of hsp70 mRNA and proteins are dramatically upregulated. However, the effects of the stress on limb and tail amputation in the newt Notophthalmus viridescens, involving mechanical tissue damage, have not adequately been examined. In the present study, three techniques were utilized to quantitate the levels of hsp70 mRNA and protein in the tissues of the forelimbs and tails of newts during the early post-traumatic events following surgical resection of these:: appendages. These included quantitative Western blotting of proteins separated by both one and twodimensional SDS-polyacrylamide gel electrophoresis and quantitative Northern blot analysis of total RNA. In tissues of both the limb and tail one hour after amputation, there were no significant differences in the levels of hsp70 protein measured by one-dimensional SOSPAGE followed by Western blotting, when compared to the levels measured in the unamputated limb. A 30 minute heat shock at 35°C failed to elicit an increase in the levels of hsp70 protein in these tissues. Further analysis using the more sensitive 20 PAGE separation of stump tissue proteins revealed that at least some of the five hsp70 isoforms of the newt may be differentially regulated in limbs and tails in response to trauma. It appears also that amputation of the tail and limb tissues leads to slight 3 elevation in the levels of HSP70 mRNA when compared to those of their respective unstressed tissues.

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[Tesis] (Doctor en Ciencias con Especialidad en Microbiología) U.A.N.L.

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Avec l’échec des négociations entre les États-Unis et la Corée du Nord, menées depuis le début des années 1990, sur la question du nucléaire, le problème est devenu graduellement l’affaire des pays voisins, tous soucieux de l’avenir de la région du sud-est asiatique. Présentée comme le seul allié de la Corée du Nord, la China a été invitée à participer à des négociations à trois, à quatre (1997-1998), et à six (2003-2007), dans l’espoir de faire entendre raison au régime isolé, mais jusqu’à maintenant, aucune des tentatives n’est parvenue à satisfaire chacun des membres à la table. Alors que la tension monte et que la politique américaine se fait de moins en moins flexible, la Chine quant à elle, continue d’encourager le retour des négociations à six (Six-Party Talks) dans l’optique de dénucléariser la péninsule coréenne, tout en travaillant à maintenir ses liens avec la Corée du Nord. Le fil conducteur de cette présente recherche est d’abord d’essayer de comprendre pourquoi la Chine continue de soutenir la Corée du Nord, fournissant dons alimentaires et financiers. L’idée est donc d’analyser, selon les principes du réalisme néoclassique, la politique étrangère de la Chine. L’hypothèse principale de cette théorie renvoie à l’idée que la distribution du pouvoir dans le système international influence la politique étrangère des États, mais que des variables au niveau de l’état et/ou de l’individu interviennent dans la formulation et l’application de celle-ci. Il est proposé ici que le lien entre l’unipolarité du système international et la politique nord-coréenne de la Chine, est façonné par des variables intermédiaires telles que : a) la perception des leaders de la distribution du pouvoir et de leur place dans le système international; b) l’idéologie du régime politique, et; c) le type d’unité responsable de la prise de décision en politique étrangère. L’analyse de chacune des variables permettra de faire la lumière sur les intérêts politiques et économiques de la Chine dans l’entretien de cette relation avec la Corée du Nord.

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L’expérience de douleur et la réponse à son traitement sont teintées par les facteurs psychologiques, parmi lesquels figurent les attentes. Cette thèse propose de raffiner la compréhension de l’effet des attentes sur la régulation de la douleur par l’entremise de deux études quantitatives. D'abord, une étude expérimentale explore l'impact des attentes sur l'analgésie induite par contre-stimulation. Des volontaires sains ont été assignés à une condition contrôle ou à l’un des trois groupes au sein desquels les attentes étaient évaluées (attentes a priori) ou manipulées par l’entremise de suggestions (hyperalgésie ou analgésie). La douleur, l’anxiété et le réflexe nociceptif de flexion en réponse à des stimulations électriques ont été mesurés avant, pendant et après l’application d’un sac de glace. Les résultats suggèrent que les attentes a priori prédisent l’amplitude de l’analgésie, tandis que les attentes suggérées parviennent à potentialiser ou à bloquer les mécanismes endogènes d'inhibition de la douleur déclenchés par la contre-stimulation, indépendamment du niveau d’anxiété. Ensuite, une étude clinique se penche sur l'apport des attentes aux issues thérapeutiques de patients traités en centres multidisciplinaires de gestion de la douleur chronique. Préalablement au traitement, les attentes des patients quant aux résultats anticipés après six mois de traitement ont été évaluées. Les changements dans l’intensité douloureuse, les symptômes dépressifs, l’interférence de la douleur et la dramatisation face à la douleur, ainsi que l’impression de changement et la satisfaction face au traitement ont été évalués au suivi de six mois. Les résultats d'analyses de modélisation par équations structurelles appuient la relation prédictive entre les attentes et les issues thérapeutiques et soulignent l’impression de changement du patient comme variable médiatrice de cette association. En plus de se montrer supérieur à un modèle alternatif, ce modèle s'est avéré pertinent à travers différents sous-groupes. Dans l'ensemble, cette thèse contribue à démontrer le rôle déterminant des attentes dans le contexte de la douleur, tant au niveau physiologique que thérapeutique. Les conclusions qui se dégagent de cet ouvrage entraînent des retombées non négligeables et réitèrent la nécessité de considérer la perspective du patient afin d'optimiser les soins destinés au soulagement de la douleur.

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Poor cold flow properties of vegetable oils are a major problem preventing the usage of many abundantly available vegetable oils as base stocks for industrial lubricants. The major objective of this research is to improve the cold flow properties of vegetable oils by various techniques like additive addition and different chemical modification processes. Conventional procedure for determining pour point is ASTM D97 method. ASTM D97 method is time consuming and reproducibility of pour point temperatures is poor between laboratories. Differential Scanning Calorimetry (DSC) is a fast, accurate and reproducible method to analyze the thermal activities during cooling/heating of oil. In this work coconut oil has been chosen as representative vegetable oil for the analysis and improvement cold flow properties since it is abundantly available in the tropics and has a very high pour point of 24 °C. DSC is used for the analysis of unmodified and modified vegetable oil. The modified oils (with acceptable pour points) were then subjected to different tests for the valuation of important lubricant properties such as viscometric, tribological (friction and wear properties), oxidative and corrosion properties.A commercial polymethacrylate based PPD was added in different percentages and the pour points were determined in each case. Styrenated phenol(SP) was added in different concentration to coconut oil and each solution was subjected to ASTM D97 test and analysis by DSC. Refined coconut oil and other oils like castor oil, sunflower oil and keranja oil were mixed in different proportions and interesterification procedure was carried out. Interesterification of coconut oil with other vegetable oils was not found to be effective in lowering the pour point of coconut oil as the reduction attained was only to the extent of 2 to 3 °C.Chemical modification by acid catalysed condensation reaction with coconut oil castor oil mixture resulted in significant reduction of pour point (from 24 ºC to -3 ºC). Instead of using triacylglycerols, when their fatty acid derivatives (lauric acid- the major fatty acid content of coconut oil and oleic acid- the major fatty acid constituents of monoand poly- unsaturated vegetable oils like olive oil, sunflower oil etc.) were used for the synthesis , the pour point could be brought down to -42 ºC. FTIR and NMR spectroscopy confirmed the ester structure of the product which is fundamental to the biodegradability of vegetable oils. The tribological performance of the synthesised product with a suitable AW/EP additive was comparable to the commercial SAE20W30 oil. The viscometric properties (viscosity and viscosity index) were also (with out additives) comparable to commercial lubricants. The TGA experiment confirmed the better oxidative performance of the product compared to vegetable oils. The sample passed corrosion test as per ASTM D130 method.

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A distinct cold tongue has recently been noticed in the South China Sea during the winter monsoon, with the cold tongue temperature minimum occurring in the January or February. This cold tongue shows signi¯cant links with the Maritime Continent's rainfall during the winter period. The cold tongue and its interaction with the Maritime Continent's weather were studied using Reynolds SST data, wind ¯elds from the NCEP{NCAR reanalysis dataset and the quikSCAT dataset. In addition, rainfall from the GOES Precipitation Index (GPI) for the periods 2000 to 2008 was also used. The propagation of the cold tongue towards the south is explained using wind dynamics and the western boundary current. During the period of strong cold tongue, the surface wind is strong and the western boundary current advects the cold tongue to the south. During the period of strong winds the zonal gradient of SST is high [0.5±C (25 km)¡1]. The cold tongue plays an important role in regulating the climate over the Maritime Continent. It creates a zonal/meridional SST gradient and this gradient ultimately leads in the formation of convection. Hence, two maximum precipitation zones are found in the Maritime Continent, with a zone of relatively lower precipitation between, which coincides with the cold tongue's regions. It was found that the precipitation zones have strong links with the intensity of the cold tongue. During stronger cold tongue periods the precipitation on either side of the cold tongue is considerably greater than during weaker cold tongue periods. The features of convection on the eastern and western sides of the cold tongue behave di®erently. On the eastern side convection is preceded by one day with SST gradient, while on the western side it is four days.

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A total of 34 yeast isolates were characterized from 4 water samples collected from Kongsfjord at Ny Alseund region of Norwegion Artic during the Indian Artic summer expedition of 2009.They were studied for the effect of tempereture and salt concentration on growth as well as for their ability to produce various hydrolytic enzymes at two different temperatures. Result showed that 5 out of 8 genera were common to all the stations. Cryptococcus was the predominant genera folowed by Trichosporan and Rhodotorula 82% of the yeast isolates were oxidative in nature and except filobasidium all the isolates used nitrate as a nitrogen source for growth. Yeast isolates from all the ststions showed growth at 4 and 20 degree centigarade. These temperatures were chosen as most of the bacterial and yeast isolates showed psychrotrop[hic nature. 94% of the yeast isolates showed growth at 2.0M and lipolytic activity were marginally less than 4.None of the isolates produced amylase enzymes when incubated at 4 and 20. The present study highlights the wide tolerence of the psychrotrophic yeast isolates to temperature and salinity as well as their potential in biotechnology

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A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-delayed offresonant femtosecond laser pulses. The laser light couples to the molecular polarization anisotropy, inducing rotational wavepacket dynamics. An interferogram is obtained from the delay dependent populations of the final field-free rotational states. Current experimental capabilities for cooling and preparation of the initial state are found to yield an interferogram visibility of more than 80%. The interferograms can be used to determine the polarizability anisotropy with an accuracy of about ±2%, respectively ±5%, provided the uncertainty in the initial populations and measurement errors are confined to within the same limits.