Thermal equilibrium of goats

The effects of air temperature and relative humidity on thermal equilibrium of goats in a tropical region was evaluated. Nine non-pregnant Anglo Nubian nanny goats were used in the study. An indirect calorimeter was designed and developed to measure oxygen consumption, carbon dioxide production, methane production and water vapour pressure of the air exhaled from goats. Physiological parameters: rectal temperature, skin temperature, hair-coat temperature, expired air temperature and respiratory rate and volume as well as environmental parameters: air temperature, relative humidity and mean radiant temperature were measured. The results show that respiratory and volume rates and latent heat loss did not change significantly for air temperature between 22 and 26 °C. In this temperature range, metabolic heat was lost mainly by convection and long-wave radiation. For temperature greater than 30 °C, the goats maintained thermal equilibrium mainly by evaporative heat loss. At the higher air temperature, the respiratory and ventilation rates as well as body temperatures were significantly elevated. It can be concluded that for Anglo Nubian goats, the upper limit of air temperature for comfort is around 26 °C when the goats are protected from direct solar radiation.     

Thermal degradation of glucosinolates

Three glucosinolates (allyl-, benzyl- and 2-phenethyl-) were shown to degrade thermally in a GC column to yield products identical with those obtained conventionally on enzymic decomposition, namely nitriles and isothiocyanates. Nitriles were formed more readily at 125° but the facility for isothiocyanate production varied slightly with the glucosinolate; 2-phenethylglucosinolate was the most labile of those studied yielding isothiocyanate at a column temperature of 150°. Temperature was confirmed as the cause of degradation by isolated heated-tube experiments. The results have significance both with regard to analytical methodology for glucosinolates and their products, and with regard to furthering understanding of the mechanisms of glucosinolate degradation.     

Thermal stability of proteins

The maximum melting points of 14 proteins in respect to pH are reported, the correlation coefficient between the hydrophobic index and the melting point was +0.622, and that between the average residue volumes and the melting points was +0.960. The correlation coefficient between the average residue volume and the hydrophobic index was +0.697. The least square relation between the melting points of the proteins and hydrophobic index and the average residue volumes considered as independent variables yielded a positive coefficient for the average residue volume and a negative coefficient for the hydrophobic index.     

Thermal behaviour of crustaceans

Specific thermoreceptors or putative multimodal thermoreceptors are not known in Crustacea. However, behavioural studies on thermal avoidance and preference and on the effects of temperature on motor activity indicate that the thermosensitivity of crustaceans may be in the range 0.2-2 degrees C. Work on planktonic crustaceans suggests that they respond particularly to changes in temperature by klinokinesis and orthokinesis. The thermal behaviour of crustaceans is modified by thermal acclimation among other factors. The acclimation of the critical maximum temperature is an example of resistance acclimation, while the acclimation of preference behaviour may be classified as capacity acclimation of some other function. In crustaceans, the use of the concepts stenothermy and eurythermy at the species level is questionable, and it is not possible to divide crustacean species into thermal guilds as suggested for fishes. Thermal preference behaviour contributes to fitness in different ways in different species, often by maximising the aerobic metabolic scope for activity. In crustaceans the peripheral nervous system seems to have retained the capacity for thermosensitivity and thermal acclimation independently of the central nervous system control of behaviour.     

Thermal torsion of F-actin

The equipartition theorem is used to calculate the mode amplitudes for F-actin thermal torsion. The amplitudes phi n are found to scale as n-1, (EI)-1/2, and L1/2, where n is mode number, EI is actin bending stiffness, and L is filament length. Depending on conditions, the amplitude can be as large as 15 degrees; this is discussed briefly in terms of skeletal muscle mechanics.     

番茄红素热处理异构化方法研究

番茄红素在受热的情况下会发生反式异构体(all-trans)向顺式异构体(cis-isomers)的转化。本文研究了乙酸乙酯热回流、微波法及超声-微波协同法对番茄红素异构化的影响。结果表明:乙酸乙酯热回流处理后,6%番茄红素油树脂中顺式异构体占比高于90%番茄红素中顺式异构体占比;氮气保护对番茄红素的异构化无明显保护作用;微波对番茄红素异构化有较强的促进作用,处理5 h后顺式占比可以高达54.7%,但超声-微波协同法对番茄红素异构化的影响与微波单独使用时无明显变化。所以微波是较好的番茄红素热处理异构化方法。     

Thermal transitions of proteins

A new method for monitoring the thermal transitions of proteins is described. An unbuffered solution of native protein shows a significant and fairly abrupt change in pH as the protein becomes heat denatured. Suitable plots permit the “melting point” of the protein to be assigned. Twenty proteins have been studied with emphasis on egg albumin. The transition temperature of egg albumin is independent of protein concentration, of pH in the neutral zone, is moderately dependent on the rate of heating, increases with increasing NaCl concentration, varies inversely with the guanidine hydrochloride concentration. There is more than a 35 °C spread in the melting temperatures of the various proteins and no apparent relation exists between the melting temperature of a protein and structural features of the protein.     

Thermal knot fixation

Knots represent the weakest point in suture material. As a result of bending and tension, forces develop within the knot that exceed the strength of the suture material and lead to rupture. Furthermore, because of their relatively large surface area, the most pronounced reactions occur in the vicinity of knots. The results of in vitro experiments conducted with the aim of improving the strength of knots are reported. The knot holding capacity of polypropylene filaments (EP 5/USP 2) was determined at room temperature (22 degrees C) after exposure to temperatures of 63, 98 and 150 degrees C. Knots that were exposed to a temperature of 98 degrees C for 10 seconds had a 50% higher holding capacity than untreated knots. With a higher knot holding capacity, secure fixation can be achieved with fewer knots. Since fewer knots have a smaller surface area, a reduction in tissue reaction may be expected.     

Thermal resistance units

A proposal is made for standardization of the constant of proportionality used to derive thermal resistances in units of seconds per metre. The choice of a standard value equal to the volumetric specific heat of air at STP would reduce ambiguity in current publications and offer a rational conversion for the clo unit of insulation, as 1 clo = 200 sm^?1 (2 s cm^?1), which gives an alternative easily visualised reference for clothing insulation.     

Thermal hysteresis proteins

Extreme environments present a wealth of biochemical adaptations. Thermal hysteresis proteins (THPs) have been found in vertebrates, invertebrates, plants, bacteria and fungi and are able to depress the freezing point of water (in the presence of ice crystals) in a non-colligative manner by binding to the surface of nascent ice crystals. The THPs comprise a disparate group of proteins with a variety of tertiary structures and often no common sequence similarities or structural motifs. Different THPs bind to different faces of the ice crystal, and no single mechanism has been proposed to account for THP ice binding affinity and specificity. Experimentally THPs have been used in the cryopreservation of tissues and cells and to induce cold tolerance in freeze susceptible organisms. THPs represent a remarkable example of parallel and convergent evolution with different proteins being adapted for an anti-freeze role.