Increase In Thermal Sensitivity Research Articles

Microbiological stabilization of fresh cow’s milk (<i>Bos taurus</i>) by ultrasonic pretreatment and low temperature thermal treatment

The objective of this applied experimental research was to evaluate the microbial stabilization of pre-sonicated fresh milk by low temperature thermal treatment (≤60 °C), to reduce its perishability. Fresh milk was sonicated with an energy density of 0.5 kJ/mL before being thermally treated at low temperature (40 to 60 °C) for different times; The pre-sonicated and thermally treated milk was evaluated for its content of Total Mesophilic Aerobes (AMV) and Total Coliforms (TC), and the effect of the treatment on microbial populations was modeled using the Bigelow Model. It was determined that treatments between 40 and 45 °C generated population increases; but those treatments above 55.04 °C for AMV and 49.28 °C for CT initiated microbial inactivation processes, both temperatures being the lowest inactivation temperatures reported so far for fresh milk. The increase in thermal sensitivity would be linked to the production of sub-lethal damage to AMV and CT cells, which would allow fresh milk to be microbiologically stabilized at lower temperatures, reducing the deleterious effects of thermal treatments.

Formation of targets and investigation of Mn4Si7 coatings produced by magnetron sputtering

The morphology, composition, electrical and optical properties of bulk samples and vacuum coatings of Mn4Si7 obtained by magnetron sputtering on a SiO2/Si structure were studied. It is shown that manganese silicide coatings with a thickness of about 150 nm are close in properties to bulk Mn4Si7, have a uniform finegrained structure of a semiconductor nature, which is characterized by thermal sensitivity up to 20-30 μV per degree. In addition, this article presents the electrophysical properties of high manganese silicide films produced by the authors by magnetron sputtering method. Heated films Mn4Si7 -146 nm coating has a uniform structure with fine grains, due to sufficient coating density. Since Mn4Si7 nanoclusters are semiconductor materials, it can be assumed that there will be energy barriers for charge carriers at the nanocluster–amorphous phase interface separating this phase. An increase in thermal sensitivity from 0 μV/K to 20 μV/K up to 800 K is explained by the disappearance of energy barriers for charge carriers at the nanocluster–amorphous phase interface due to the ordering of nanoclusters. The change from 20 µV/K to 28 µV/K upon cooling is explained by the appearance of structural relaxation in the amorphous phase.

The potential use of acylglycerols on the thermal inactivation of lactic acid bacteria for the manufacture of long-life fermented products

The effect of acylglycerols on the thermal inactivation of lactic acid bacteria used in the production of fermented products was studied. The starting point was the observation of an increase in thermal sensitivity in the presence of an emulsifier based on mono- and diacylglycerols in the culture medium. Analysis of the emulsifier showed that monoacylglycerols were the compounds responsible for this effect, with monopalmitin being the main contributor. Monostearin, on the other hand, showed significantly less potentiating effect. Interestingly, monoacylglycerols showed a greater bactericidal effect when used individually than when used in combination. On the other hand, the rate of thermal inactivation observed in reconstituted skim milk emulsions was lower than in peptone water emulsions, showing that the presence of proteins and colloidal particles increased the resistance of bacteria to heat treatment. With respect to pH values, a reduction in pH from 6.6 to 5.5 promoted an increase in the rate of thermal death. However, at pH = 5.5, the enhancing bactericidal effect was only detectable when the heat treatment was performed at low temperatures but not at high temperatures. This finding is of interest, since it will allow the design of moderate heat treatments, combining the use of temperature with the addition of acylglycerols, to prolong the shelf life of products fermented with lactic acid bacteria, and minimizing the destruction of desirable compounds that were obtained by the fermentation process.

Theoretical study of thermal response of bimaterial microcantilevers with different coating materials

Bilayer microcantilevers are a versatile tool in thermal and bio-sensing with responses relying on the mismatch between the two constituting materials. The cantilever response, such as a deflection and resonance frequency shift, could be involved when the cantilever is in contact with an arbitrary heat source in the ambient environment. In this study, thermally induced deflection will be theoretically examined assuming a heat source located at various positions on the cantilever. The combined contributions of heat absorption, thermal conductivity, and material rigidity on the final deflection will be revealed. Selecting an optimal position leads to 1.5 times enhancement of the cantilever deflection in comparison to thermal excitation at the cantilever end in conventional experiments, which implies a significant increase in thermal sensitivity. Furthermore, responses of cantilevers with different coating materials (Au, Al, Cu, or Ni) have been examined and show a dominant sensitivity of Al- and Ni- over Cu- and Au-coated cantilevers. These results could help to explain recent experimental results and to choose an optimal thermal excitation of microcantilevers in sensing.

Diameter dependent thermal sensitivity variation trend in Ni/4H-SiC Schottky diode temperature sensors

This report is on the diameter dependent thermal sensitivity variation trend of Ni/4H-nSiC Schottky barrier diode (SBD) temperature sensors. Scaled SBDs of 2, 1.6, and 1.2 mm in diameter were fabricated using standard photolithography process comprising a field plate and a guard ring as edge terminations on the same epitaxial wafer. Taking into consideration the heat loss and power consumption, the thermal sensitivities of the fabricated SBDs were measured in the current range from 1 μA to 50 pA. The temperature was varied from 273 to 473 K in step of 25 K. An authoritative consequence of the present study is the observed increase in thermal sensitivity with the diameter of the fabricated SBDs. An exhaustive investigation confirms that in all diodes, there exist nanosized patches, which assumed to have different barrier heights and hence ascertained to be the main cause of anomalies in thermal sensitivity variation with diode size. Taking into account the effective area of these patches, theoretically fitted I–V curves to experimental data show that the numbers of patches were higher in diode with least size and decrease with the increase in the size of the diode. The corresponding barrier heights of these patches were found to be distributed in a Gaussian like manner at the fabricated Ni/4H-nSiC interface with least standard deviation (σ0) in the diode of maximum size.

Thermal sensitivity as a measure of spontaneous morphine withdrawal in mice

IntroductionOpioid withdrawal syndrome is a critical component of opioid abuse and consists of a wide array of symptoms including increases in pain sensitivity (hyperalgesia). A reliable preclinical model of hyperalgesia during opioid withdrawal is needed to evaluate possible interventions to alleviate withdrawal. The following study describes a method for assessing increases in thermal sensitivity on the hotplate in a mouse model of spontaneous morphine withdrawal. MethodsC57BL/6J mice received 5.5days of 30, 56, or 100mg/kg morphine or saline (s.c., twice daily). In Experiment I, thermal sensitivity data were collected at baseline and at 8, 24, 32, 48h and 1week following the final injection. Thermal sensitivity was assessed by examining latency to respond on a hotplate across a range of temperatures (50, 52, 54, and 56°C). In Experiment II, 0.01mg/kg buprenorphine was administered 30min prior to each testing session during the withdrawal period. In Experiment III, jumping during a 30min period was assessed at baseline and at 0, 8, 24, 32, and 48h following the final morphine injection. ResultsDuring the withdrawal period, thermal sensitivity increased significantly in all morphine-treated mice as compared to saline-treated mice. Thermal sensitivity was greater in mice treated with 56mg/kg morphine compared to 30mg/kg and peaked earlier than in mice treated with 100mg/kg (32h v 1wk). The increase in thermal sensitivity following 56mg/kg morphine was attenuated by a dose of buprenorphine that did not produce antinociception alone (i.e., 0.01mg/kg). In general, the results of the jumping experiment paralleled those obtained in Experiment I. DiscussionResponse latency on the hotplate is a reliable and sensitive measure of spontaneous morphine withdrawal in mice, making it an ideal behavior for assessing the potential of medications and environmental interventions to alleviate opioid withdrawal.

Characterization of nerve growth factor‐induced mechanical and thermal hypersensitivity in rats

Injection of nerve growth factor (NGF) produces mechanical and thermal hypersensitivity in rodents and humans. Treatment with sequestering antibodies demonstrates the importance of NGF in various pain states, with efficacy seen in a number of animal pain models and in painful human conditions. However, these phenomena have not been evaluated in the context of using NGF-induced hypersensitivities as a model of pain. NGF-induced behaviours were characterized using von Frey filament, pinprick and thermal endpoints and then pharmacologically evaluated with known reference agents. Intraplantar NGF injection produced a dose-dependent increase in thermal sensitivity that lasted through 24 h post-injection and an immediate long-lasting (2 week) increase in mechanical sensitivity at the injection site, with no effects detected at secondary sites. NGF-induced mechanical sensitivity was pharmacologically characterized at 4 h and 1 week post-NGF injection. The nonsteroidal anti-inflammatory drugs (NSAIDs), celecoxib and diclofenac, were minimally effective against both thermal and mechanical endpoints. Gabapenitn and duloxetine were only moderately effective against thermal and mechanical hypersensitivity. Morphine was effective against thermal and mechanical endpoints at every time point examined. Treatment with the transient receptor potential vanilloid 1 (TRPV1) antagonist A-784168 partially attenuated NGF-induced thermal and mechanical sensitivity at all time points examined. The results reported here suggest that effects of NGF on thermal and mechanical sensitivity in rats are similar to those reported in human and are partially driven by TRPV1. The rat NGF model may serve as a potential translational model for exploring the effects of novel analgesic agents.

The effect of environmental factors on morphine withdrawal in C57BL/6J mice: running wheel access and group housing

There is evidence to suggest that the rewarding effects of drugs of abuse can be altered by environmental manipulations such as housing conditions and access to running wheels. There is less information about how these environmental manipulations alter withdrawal behaviors following the termination of chronic drug administration. The objective of this study is to examine the effects of access to running wheels and group housing on spontaneous morphine withdrawal. C57BL/6J mice were assigned to one of the three housing conditions: wheel access (singly housed), no wheels (singly housed), or group-housed (no wheels). Mice received 30 or 56 mg/kg morphine or saline (s.c.) twice daily for 5.5 days. At baseline and at 8, 24, 32, and 48 h following the final injection, latency to respond on a hot plate was determined across a range of temperatures (50, 52, 54, and 56 °C). Latency to respond decreased as a function of temperature. Response latencies during the withdrawal period were decreased in mice without wheel access treated with both 30 and 56 mg/kg of morphine. This increase in thermal sensitivity was significantly attenuated in singly housed mice with wheel access and in group-housed mice; however, the effects were less pronounced in the group-housed mice and depended upon the time during withdrawal. Both wheel access and group housing attenuate the increase in thermal sensitivity seen in morphine-treated mice during morphine withdrawal.

RELATIONS BETWEEN TEMPERATURE SENSITIVITY AND MORPHOGENESIS IN TETRAHYMENA PYRIFORMIS GL.

SYNOPSIS. The division delay responses of Tetrahymena (“set‐back” curves) which result from heat shocks of the type used in synchronizing studies have been examined in logarithmic and synchronized T. pyriformis GL. The curves indicate an increasing sensitivity to heat shocks with increasing cell age, a sudden sharp increase just prior to the “transition point” and a loss of sensitivity at the transition point. A correlated study of morphogenesis in the synchronous generation suggests that the sudden increase in thermal sensitivity before the transition point is due to a dedifferentiation and redifferentiation of the developing oral primordium which can be induced at this time. The results also suggest that the “stabilization” of the primordium which follows the transition point may occur at more than one developmental stage, i.e., is not stage‐specific. It is suggested that stabilization may therefore be due to conditions lying outside the primordium.