微量量热法筛选抑菌特效药的研究

用微量最热计连续测定细菌代谢过程中的热显变化，可获得反映细菌代谢规律的完整的热谱图以按指数生长模型对指数生长期进行处理，可计算出细菌正常代谢的生长速率常数L’．若在培养基中加入合成药物，使细菌在药物抑制作用下生长，也可获得完整的热谱图，从而计算出在药物抑制作用下细菌的生长速率常数．本义对福氏志贺氏Zb菌和金黄色葡萄球莉在四种合成药物抑制作用下的热谱进行了测定，并计算了生长速率常数，找出了细菌生长速率常数与所用药物浓度之间的定量关系，可为筛选抑菌药物和确定用药显提供定量依据’1基本原理设细菌在代谢过…     

细菌最佳生长的热化学研究

细菌最佳生长的热化学研究刘义，冯英，谢昌礼，屈松生，冯长健，乐芝凤（武汉大学化学系武汉４３００７２）（华中师范大学化学系武汉）关键词　细菌最佳生长温度，席夫碱，热化学，微量热法用微量热法研究细菌生长代谢过程已有大量报道［１～４］，可求出细菌生长的速率...     

环境气氛对微量热安瓿法测定细菌生长速率常数的干扰

采用微量热安瓿法测定细菌生长时,发现细菌的代谢产热曲线在第一指数生长期内出现了停留法没有报导过的显著分阶段现象,且在不同的阶段生长速率常数有很大差异,对药物抗菌性能的评估造成极大干扰.为了寻找此现象的可能原因,以具有代表性的兼性细菌大肠杆菌为例,设计了微量热安瓿法实验,考察了不同环境气氛下大肠杆菌的生长代谢产热;并模拟了停留法条件下细菌的生长环境,通过安瓿法测定了大肠杆菌的生长代谢产热,重新解析了这些条件下细菌的生长速率常数.结果表明环境气氛是造成此现象的主要可能因素,并为在不同环境气氛下采用微量热安瓿法准确评估细菌的生长速率提供了一个可参考的标准.     

热动力学研究的新进展

根据变化过程的放（吸）热速率研究过程动力学规律并融热化学与化学动力学于一体的分支学科称为热动力学。本文回顾了国内外学者在各种量热体系中研究热动力学的进展情况，着重介绍了最近五年中热动力学在化学反应、酶促反应和生物代谢过程研究中的应用，并预测了热动力学在未来十年中的发展趋势。     

细菌变异株生长热谱研究

用微量热法研究微生物的生长与代谢,是生物热力学一个新的研究领域.我们已经测得细菌生长的完整热谱,这种热谱具有良好的重现性和明显的特征性,可以作为细菌的“指纹图”对其进行种的分类和鉴定[1～5].但在研究中发现,同种细菌不同变异株的生长图谱略有差异,若培养基选择?..     

等温微量热法在生命科学研究中的应用

简要介绍了等温微量热法的原理、典型的仪器及其在生命科学研究中应用所具有的特点。通过它可获得完整的细胞代谢过程产热曲线及其热动力学方程；可以研究细胞器的代谢规律；可以获取生物大分子与小分子相互作用的热动力学特征。     

用微量热法研究左金丸及类方药的药性差异

采用微量热法测定了大肠杆菌在左金丸、甘露散、茱萸丸和反左金丸水煮液作用下的生长热谱曲线,获得相应的生物热动力学参数,经主成份分析并结合本草文献报道,综合分析左金丸及类方的药性差异,以从生物物理和生物化学的角度,探讨中医经典类方药性差异的客观真实性.实验发现,左金丸及类方的水煮液对大肠杆菌的生长代谢表现出不同的活性作用.寒凉药方左金丸和甘露散不同程度的抑制细菌的生长代谢.温热药方反左金丸和茱萸丸对细菌的生长代谢有不同程度的促进作用.类方之间存在较稳定的药性差异.类方药性主要受生物热动力学参数:第二指数生长期的生长速率常数k2和最大发热功率Pm2的影响.     

微量热法测定细菌的临界生长温度

应用微量热学的方法,我们已能成功地测得细菌生长过程的热谱,这种热谱包含着有关细菌生长代谢过程的丰富信息,例如对热谱曲线的指数生长段进行解析,可得出细菌生长的速率常数、激活能和有关的热力学参数。故采用微量热法测定细菌在不同培养温度下的生长速率常数,利用计算机拟合出相应k(速率常数)和T(培养温度)的线性关系式后,若把生长速率为零的温度定义为临界生长温度时,就可以根据由上述实验所得的k～T线性关系式求得细菌的临界生长温度。本工作仍采用微量热法对福氏志贺氏菌(S. flexneri)和大肠埃希氏菌(E. coli)进行实验测定。按文献的方法求出它们在不同温度下的生长速率常数;对于大肠埃希氏菌还用几种不同的培养基分别进行实验测定。     

药物对福氏志贺氏菌代谢抑制的微量热法研究

药物抑制细菌生长的热化学研究是当今热化学法研究的一个活跃领域．在这项研究中，Boling[1]、Nordmark[2]、屈松生[3]等人已做了不少有意义的工作．在前人工作的基础上，我们用热活性检测系统测定了福氏志贺氏菌属中五株细菌在药物抑制下生长的完整的热谱曲线．按指数生长模型计算出细菌代谢抑制下的生长速车常数，并用计算机拟会出生长速率常数与不同浓度药物之间的关系式，进一步得到生长速率常数为零（临界生长参数[4]）时的用药物浓度．此项研究工作的开展对于深入研究药物对细菌的抑制作用，筛选对某细菌抑制的特效药提供了一种新的…     

盐生盐杆菌生长过程热动力学研究

用 LKB2 2 77生物活性检测系统测定了盐生盐杆菌 R1、J7、S9以及 R1和 J7的融合子 F9生长的产热功率曲线 .根据曲线的特征 ,建立了古生菌生长过程的热动力学方程 :ln[P· ( 1 -P/Pm) r- 1 ]=ln[P0 · ( 1 -P0 /Pm) r- 1 ]+k· t.由此求得了盐生盐杆菌的生长速率常数 ,并对此模型和融合子 F9的生长进行了讨论 .该热动力学方程描述了一系列非理想的细菌生长过程的产热功率曲线 ,并将其与经典的指数式生长模型和 lo-gistic模型进行了比较 ,它具有更广泛的适用性 .首次报道了微量热技术在古生菌中的应用     

Design and testing of a calorimeter for biological uses

A rotatory microcalorimeter of the conduction type has been designed for the study of microbial metabolic processes under both aerobic and anaerobic conditions. The instrument can be performed in either batch mode or flow mode by changing the calorimeter vessels and the tube connections. The sensitivity and the time constant were determined by electrical calibrations. The heat sensitivity was 0.12 mV/mW with both yeast and other fungi. Because of the sufficient aeration and agitation, the calorimeter is available for studies on the fungi growth experiments of biotechnical interest.     

Heat conduction effects during the calorimetric determination of absorbed dose to water in radiotherapy beams

A transportable water calorimeter for the determination of the quantity of absorbed dose to water in radiotherapy beams has been developed at the PTB and is presented in detail in this investigation. Heat conduction effects occurring in the calorimeter are studied for different lateral sizes of high-energy photon beams, for different depth dose distributions of electron beams and for a scanned-beam irradiation with a heavy ion beam. The corresponding correction factors are calculated and arguments are given under which conditions these can adequately be applied.     

Thermokinetic Research Method for Bacterial Growth in Conduction Calorimeter

This paper presents the basic equations of thermokinetics and the thermoanalytical curve equation for bacterial growth in conduction calorimeter on the basis of the basic theory of thermokinetics. The bacterial growths in the log phase for Vibro metschnikovii and Bacillus subtilis at different temperatures were calorimetrically investigated. The rate constant of bacterial growth, the cooling constant of the thermokinetic system, the generation time and the pre-exponential factor at different temperature were obtained, which allowed to evaluate the activation energy of bacterial growth (E _a). According to the transition-state theory of chemical kinetics, the activation enthalpy (ΔS ^≠), the activation Gibbs free energy (ΔG ^≠) and equilibrium constant (K ^≠) of the activated state at different temperatures were also obtained. The above results showed that the research method suggested in this paper was reasonable. This revised version was published online in August 2006 with corrections to the Cover Date.     

Design, Calibration, and use of convective air flow dynamic calorimeter

A new type of calorimeter has been developed that continously monitors the rate of heat emission from a heat source by following the rate of convective air flow induced by the emitted heat. For this purpose a thermistor version of a hot-wire anemometer connected to a strip chart recorder is positioned to measured the flow of incoming air. Details are given for the construction, calibration, and operation of a form of the calorimeter designed for studying the upward burning of unrestrained fabric samples under conditions closely approximating natural burning.     

Modelling of a high pressure calorimeter

The evaluation of the latent heat and enthalpy of fusion of food systems in the case of high pressure–low temperature processing is important for modelling purposes as well as for technical applications. A high pressure calorimeter has been designed for this purpose. The high pressure calorimeter was used to evaluate the latent heat during a pressure scan at constant temperature. It permits to measure the heat of phase transitions and to obtain the relationship between the initial freezing temperature T _ifp and the average pressure while the phase transition is going on. This work presents a modelling of results obtained from an experimental approach using a high pressure calorimeter and from a mathematical model developed from existing data on the phase change of pure water. The modelling work consisted in evaluating the latent heat measured in previous tests from computations taking into account the dependence of the latent heat of fusion of water on pressure. Models predicting the amount of frozen water in a food matrix under atmospheric conditions were used to determine the initial amount of frozen water in the sample. Then a stepwise procedure was operated in a program to reproduce the pressure rise occurring during a high pressure calorimeter test. The amount of melted ice at each pressure step was calculated using conventional ice fraction models, which were adapted to pressure dependence of the initial freezing temperature and the dependence of the latent heat pressure. The comparison was satisfactory, especially at low temperatures.     

Using cone calorimeter data for the prediction of upward flame spread rate

In a cone calorimeter, the specimen receives uniformly distributed irradiance from the cone heater. Producing a heating environment simulating the heating intensity in real fires, this apparatus consequently is capable of providing information of materials relevant to their fire performance. Several previous upward flame spread models utilized the data as input with an assumption of uniformly distributed heat fluxes. Satisfactory flame spread rates were predicted. However, the heat flux in the heating region in upward flame spread is not uniform. This study introduces an alternative protocol of the cone calorimeter and a sample holder by which the following differences were made, including specimen turned 42° before ignition, lower ignition source before ignition, heater removed after ignition, and specimen moved back to vertical orientation after ignition. The heating environment is more consistent to real wall fire conditions. In addition, the prediction of flame spread rate using the alternative test protocol is closer to the measured flame spread rate than standard test methods.     

Verification of calorimetric models based on physical parameters by frequential characteristics

Quantitative criteria to ascertain the quality of calorimetric models based on physical parameters are presented. These include not only a comparison between model and experimental pulse responses, especially for the larger time constants, but also an analysis of their spectra up to the frequential limit brought about by the experimental noise.A calorimetric model based on the physical parameters of a Unipan 600 calorimeter is used to reconstruct a given power dissipation. The results are then compared to those given by other methods, i.e. dynamic optimization, inverse filtering and harmonic analysis.     

Calorimetric Study of the Bioremediation of a Polluted Soil

The calorimetric cells of a Setaram BT 2.15 flux calorimeter have been modified, in order to measure the heat production associated with microbial growth, with a continuous flow of gas and liquid through the sample. Good conditions for the growth of the microorganisms present in a polluted soil were determined and the possibility of the bioremediation examined. It was shown that the biodegradation of hydrocarbons adsorbed for a long time in the soil is a very slow process difficult to study with calorimetry. On the contrary, sodium succinate and different C₁₄ hydrocarbons were easily biodegradated, producing a large quantity of heat.This revised version was published online in November 2005 with corrections to the Cover Date.     

Osmotic and activity coefficients in dilute solutions of ethanol in cyclohexane from freezing-point measurements

The calorimeter developed in this laboratory for isothermal enthalpy-of-dilution measurements is adapted for use as an adiabatic calorimeter for freezing-point studies. Results are obtained for ethanol solutions in cyclohexane at mole fractions of ethanol from 0.001 up to 0.08. Activities calculated from the results are used to test association models.