Peltier cell calorimetry“as an option”for commonplace cryostats:Application to the case of MnFe(P,Si,B)magnetocaloric materials

Peltier cell calorimetry is a powerful technique to record both the heat capacity and the latent heat,yet its avail-ability is limited as it often requires homemade dedicated cryostats.Here,we describe the development of a Peltier cell differential scanning calorimeter facilitating the accessibility to the technique,since it is designed“as an option”for commonplace commercial cryostats equipped with high magnetic fields.This yields an appa-ratus well suited to detailed studies of magnetic transitions in general and of first-order magnetic transitions in particular.For magnetocaloric materials,our system can also be used to measure directly the isothermal entropy changeΔS induced by a magnetic field change;it even allows separating the cyclic(reversible)effect due to suc-cessive magnetization/demagnetization,which is the one relevant for applications,from the total magnetocaloric effect.To illustrate the versatility of this system,a thorough study of the ferromagnetic first-order transition of MnFe0.95 P0.585 Si_(0.34)B_(0.075)is carried out.An exceptionally large cyclic entropy change at an intermediate field is observed in this compound,ΔS_(cyclic)=13.2 J kg^(−1)K^(−1)forμ_(0)ΔH=1 T.This confirms that MnFe(P,Si,B)shows one of the most promising giant magnetocaloric effects to be used in emergent green technologies such as mag-netocaloric cooling,heating or thermomagnetic waste heat recovery.

汉麻籽多肽靶向抑制胰脂肪酶/胆固醇酯酶的分子作用机制

采用酶活动力学、联合抑制、荧光光谱、等温滴定量热法和分子对接等技术系统探究两种多肽(APAM和RLPA)对胰脂肪酶(pancreatic lipase,PL)和胆固醇酯酶(cholesterol esterase,CE)活性调控效果及分子结合机制。结果表明,RLPA对PL和CE具有更强的抑制活性,其半抑制浓度分别为(79.62±3.20)μmol/L和(301.27±14.40)μmol/L。抑制动力学分析表明APAM对两种酶的抑制机制为竞争性抑制,而RLPA则为混合性抑制。联合抑制表明APAM和RLPA在低浓度下均可与奥利司他协同抑制PL和CE,但在高浓度下协同作用减弱,甚至出现拮抗现象。荧光光谱结果表明两种多肽可以通过与PL和CE发生结合产生静态猝灭,改变了酶中脂肪族氨基酸的疏水环境。等温滴定量热法证明多肽与酶的结合过程是自发且放热,主要通过氢键和静电相互作用实现。分子对接模拟进一步分析表明氢键、盐桥和阳离子-π相互作用在多肽与酶的结合中起着至关重要的作用。这项研究丰富了对多肽与PL和CE的相互作用机制的认识,为开发基于汉麻籽蛋白的功能性食品提供了科学依据。

再生与原生涤纶纤维的特征分析

针对目前仍缺少再生涤纶纤维快速、准确的特征分析和提取方法,文章分别使用快速傅立叶变换红外光谱、热重分析、差示扫描量热法和顶空气相色谱质谱联用法,分析原生与再生涤纶纤维样品的特征官能团结构、热性能以及特征挥发性化合物。结果表明,再生涤纶纤维红外光谱吸收峰强度高于原生涤纶纤维,再生涤纶纤维经热重分析的第二段质量损失率高于原生涤纶纤维,同时顶空气相色谱质谱联用分析在再生涤纶纤维样品中检出苯甲醛和正辛醛,上述结果可作为再生涤纶纤维的检测特征。根据研究结果,在后续的研究中可累积样本量并建立数据库,为再生涤纶纤维的追溯体系提供事实基础。

聚N-乙烯基吡咯烷酮的分子量与抗冰冻性能的关系研究

一些化合物的周围不可冰冻束缚水在低温条件下可以保持液体状态。利用量热法对四种不同分子量的聚N-乙烯基吡咯烷酮的水溶液进行测定,确定聚合物周围的不可冰冻束缚水的含量,发现最高的为74.97 g水/100 g聚合物,与聚合物结构单元结合的不可冰冻水分子数为4.62个。最低的束缚水只有30.02 g水/100g聚合物,其抗冻性能较差。此聚合物的抗冻性能随分子量而变,分子量是影响其作为抗冻材料的一个重要因素。

便携式营养代谢测量系统设计

针对常态化营养代谢监测中的便携式快速测量需求,提出一种基于间接测热法的低功耗多功能测量方法与系统方案。首先,采用卡尔曼和5阶贝塞尔滤波算法相结合,对氧气、二氧化碳、流量、心电实时数据进行预处理,得到气体在单位时间内累积量;其次,设计考虑心电图和呼吸波静息分析的营养代谢快速测量方法,构建能量代谢参数计算模型;然后,设计专用采集与分析电路系统,通过无线网络将数据传输至上位机或云端,实现智能化和网络化设计;最后,采用对心电图和呼吸参数分析实现对被试的静息状态判定,进而完成营养物质代谢监测试验。结果表明该系统能有效对代谢相关生理信号进行高精度检测,同时实现对人体脂肪和糖类代谢消耗的准确测量,为人体新陈代谢能量测量提供一种有效手段。

Integrative analysis of indirect calorimetry and metabolomics profiling reveals alterations in energy metabolism between fed and fasted pigs

Background: Fasting is a simple metabolic strategy that is used to estimate the maintenance energy requirement where the energy supply for basic physiological functions is provided by the mobilization of body reserves.However, the underlying metabolic components of maintenance energy expenditure are not clear. This study investigated the differences in heat production(HP), respiratory quotient(RQ) and plasma metabolites in pigs in the fed and fasted state, using the techniques of indirect calorimetry and metabolomics.Methods: Nine barrows(45.2 ± 1.7 kg BW) were fed corn-soybean based meal diets and were kept in metabolism crates for a period of 14 d. After 7 d adaptation, pigs were transferred to respiratory chambers to determine HP and RQ based on indirect calorimetry. Pigs were fed the diet at 2,400 k J ME/(kg BW0.6·d) during d 8 to 12. The last 2 d were divided into 24 h fasting and 48 h fasting treatment, respectively. Plasma samples of each pig were collected from the anterior vena cava during the last 3 d(1 d while pigs were fed and 2 d during which they were fasted).The metabolites of plasma were determined by high-resolution mass spectrometry using a metabolomics approach.Results: Indirect calorimetry analysis revealed that HP and RQ were no significant difference between 24 h fasting and 48 h fasting, which were lower than those of fed state(P < 0.01). The nitrogen concentration of urine tended to decrease with fasting(P = 0.054). Metabolomics analysis between the fed and fasted state revealed differences in15 compounds, most of which were not significantly different between 24 h fasting and 48 h fasting. Identified compounds were enriched in metabolic pathways related to linoleic acid metabolism, amino acid metabolism,sphingolipid metabolism, and pantothenate and Co A biosynthesis.Conclusion: These results suggest that the decreases in HP and RQ of growing pigs under fasting conditions were associated with the alterations of linoleic acid metabolism and amino acid metabolism. The integrative analysis also revealed that growing pigs under a 24-h fasting were more appropriate than a 48-h fasting to investigate the metabolic components of maintenance energy expenditure.

DIFFERENTIAL SCANNING CALORIMETRY AND X-RAY DIFFRACTION STUDIES ON AGING BEHAVIOR OF Zn-Al ALLOYS

Decomposition processes of the quenched Zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities of supersaturated solid solution (SSS) of Zn-Al alloy and α' phase formed by quenching would reduce with the increase of Zn content and the precipitation of η-Zn phases even when aging at ambient temperature, so that the exothermic precipitation peak in DSC curve would disappear. The activation energy of the η-Zn precipitation and the reaction enthalpy were calculated and measured. The kinetics of α' decomposition or η-Zn formation was determined by XRD. The microstructure change during aging was observed by TEM.

New Developments in the Calorimetry of High-Temperature Materials

1. Introduction Thermodynamics forms the fundamental underpinning of reactivity, transformation, and stability, and controls processes such as synthesis, corrosion and degradation, environmental transport, catalysis, and biological reactivity. In the materials field, the wealth of new compounds, polymorphs, hybrid organic–inorganic hybrid materials and metal organic frameworks, high-entropy alloys, and multiphase and nanophase materials attained by a variety of non-equilibrium synthesis and processing methodologies has outrun the available thermodynamic data, hampering current understanding of synthetic pathways, materials compatibility, and longevity during use, degradation, corrosion, and dissolution, and limiting our understanding of environmental contamination and transport for new materials.

Assessment of parameters for precipitation simulation of heat treatable aluminum alloys using differential scanning calorimetry

Differential scanning calorimetry （DSC） has been used extensively to study different solid state reactions. The signals measured in DSC are associated with the growth and dissolution of different precipitates during a specific heat cycle. The time-temperature dependence of heat cycles and the corresponding heat flow evolution measured in the sample by DSC provide valuable experimental information about the phase evolution and the precipitation kinetics in the material. The thermo-kinetic computer simulation was used to predict the DSC signals of samples taken from 6xxx and 2xxx alloys. In the model, the evolution of different metastable and stable phases and the role and influence of excess quenched-in vacancies in the early stage of precipitation were taken into account. Transmission electron microscopy （TEM） and high-resolution TEM were used to verify the existence of precipitates, their size and number density at specific points of the DSC curves.

Indirect calorimetry to estimate energy requirements for growing and finishing Nellore bulls

Determination of nutritional requirements is the basis for diet formulation. The objectives of this study were to determine the net energy requirements for maintenance （NEro） and weight gain （NEg） in Nellore bulls during the growing and finishing phases, and to estimate efficiency of metabolizable energy （ME） utilization for maintenance and gain （km, kg）. Five Nellore bulls were housed in individual pens at the Universidade Federal de Minas Gerais （Belo Horizonte, Brazil） and evaluated over four experimental periods at 210, 315,378 and 454 kg shrunk body weight （SBW）, approximately. During each period, heat production （HP） was quantified by open circuit indirect calorimetry for three feeding levels： ad libitum, restricted and fasting. The NEm requirement was determined by linear regression between the Log of HP andthe ME intake （MEI） for the ad libitum and restricted levels. This requirement was also determined by quantifying fasting heat production （FHP）. The NEQ requirement was calculated by the difference between MEI and HP during ad libitum feeding. The k and kg were calculated by the relationship between net energy （NE） and ME requirements for maintenance and weight gain （MEm, MEp）, respectively. The NEm requirements per kg of metabolic empty body weight （EBW0.75） fluctuated between 348 and 517 kJ d-1, showing a decreasing trend with age, and were higher than the values reported in the literature. The NEg requirements ranged between 48.3 and 164 kJ kg-1 EBW0.75 d-1, and varied according to age and weight gain. The k values varied between 58.6 and 69.7%, while kg varied between 23.4 and 40.2%. We concluded that NEm and NEg requirements were influenced by age and possibly by the level of stress, nervousness and activity of animals into the respirometry chamber. Further studies should quantify HP with records of positional changes （time spent standing vs. lying down）. Additionally, HP quantification should be repeatedly performed in the same experimental period to obtain a representative value of NEg requirements.

Indirect calorimetry in obese female subjects: Factors influencing the resting metabolic rate

AIM: To evaluate selected factors influencing resting energy expenditure(REE) in obese female subjects.METHODS: Seventy seven 61 obese Caucasian women [mean age of 52.93 ± 13.45 years, and mean body mass index(BMI) of 41.78 ± 11.54 kg/m2] were enrolled; measurements of resting metabolic rate(RMR) by a ventilated, open-circuit system, indirect calorimeter were performed after an overnight fast. Body composition as well as medications, physical parameters, blood samples, disease pattern, and smoking were considered. RESULTS: RMR was significantly associated with body weight(r = 0.732, P < 0.001), body height(r = 0.401,P = 0.008), BMI(r = 0.504, P < 0.001), waist circumference(r = 0.602, P < 0.001), mid-upper arm circumference(r = 0.417, P = 0.006), mid-upper arm muscle circumference(r = 0.344, P = 0.028), total body water(r = 0.339, P = 0.035), body temperature(r = 0.409, P = 0.007), smoking(P = 0.031), serum T4 levels(r = 0.331, P = 0.036), obstructive sleep apnoea syndrome(OSAS; P = 0.023), impaired glucose tolerance(IGT; P = 0.017) and impaired glycaemic status, including hyperinsulinism, IGT and diabetes mellitus(P = 0.003).CONCLUSION: Future research should be prompted to optimize the procedure of indirect calorimetry to achieve clinical benefits in obese subjects.

Research on thermal decomposition of 1,3,5-trinitro-1,3,5-triazinane based on differential scanning calorimetry

In order to test the thermal decomposition of 1,3,5-trinitro-1,3,5-triazinane(RDX),the linear temperature rise experiment of RDX was carried out by differential scanning calorimeter under different heating rate conditions.The kinetic calculation of RDX thermal decomposition curve was carried out by Kissinger and Ozawa methods,respectively,and the thermal analysis software was used to calculate the parameters such as self-accelerating decomposition temperature.The results show that the initial decomposition temperature range,decomposition peak temperature range,and decomposition completion temperature range of RDX are 208.4-214.2,225.7-239.3 and 234.0-252.4℃,respectively,and the average decomposition enthalpy is 362.9 J·g^-1.Kissinger method was used to calculate the DSC experimental data of RDX,the apparent activation energy obtained is 190.8 kJ·mol^-1,which is coincident with the results calculated by Ozawa method at the end of the reaction,indicating that the apparent activation energy calculated by the two methods is relatively accurate.When the packaging mass values are 1.0,2.0 and 5.0 kg,respectively,the self-accelerating decomposition temperatures are 97.0,93.0 and 87.0℃,respectively,indicating that with the increase of packaging mass,the self-accelerating decomposition temperature gradually decreases,and the risk increases accordingly.

CALORIMETRY DETERMINATION OF ^(210)Po IN TARGETS

The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one. It works at room temperature and does not need any device of constant temperature. The instruments used for calorimetry are simple and have good properties. The background is from -1μV to + 2 μ V when the room temperature changs between 16℃ and 28 ℃. The data gotten in calorimetry are in correspondence within ±3.4 % with those from liquid scintillation method after the targets were dissolved, additionally in correspondence within ±1.7% with the data given by Amersham Laboratories for 241Am determination.

Interaction between Heparin and Fibronectin: Using Quartz Crystal Microbalance with Dissipation, Immunochemistry and Isothermal Titration Calorimetry

The adsorption behavior of heparin and fibronectin was studied by quartz crystal microbalance with dissipation(QCM-D), and the interaction between heparin and fibronectin was evaluated using immunochemistry and isothermal titration calorimetry(ITC) measurement. The results showed that there was competitive adsorption between heparin and fibronectin, and the preadsorption of fibronectin could prevent subsequent heparin adsorption to some extent, and the adsorbed Hep/Fn complex on the surface was in a rigid form. The bioactivity of heparin and fibronectin could be affected by the bulk concentration of each, and both heparin and fibronectin in Hep/Fn complex formed under p H 4 condition displayed larger bioactivity than that formed under p H 7 condition. Moreover, the fibronectin showed more exposed cell-binding sites at the p H value lower than physiological condition. The results of ITC further suggested that the interaction between heparin and fibronectin under p H 4 was stronger than under p H 7, and the complex was also more stable. The study brings forth the detailed interaction between heparin and fibronectin, which will be helpful for better understanding the interaction mechanism of the two biomolecules. The results may be potentially useful for the development of new generation of cardiovascular biomaterials.

Exploring the thermal stability of lithium-ion cells via accelerating rate calorimetry:A review

Given the importance of lithium-ion cell safety,a comprehensive review on the thermal stability of lithium-ion cells investigated by accelerating rate calorimetry(ARC),is provided in the present work.The operating mechanism of ARC is discussed first,including the usage and the reaction kinetics.Besides that,the thermal stability of the cathode/anode materials at elevated temperatures is revealed by examining the impacts of some significant factors,i.e.,the lithium content,particle size,material density,lithium salt,solvent,additive,binder and initial heating temperature.A comparison of the common cathode materials indicates that the presence of Mn and polyanion could significantly enhance the thermal stability of cathode materials,while the doping of Al also helps to restrain the reactivity.Except for their high capacity,some alloy materials demonstrate more competitive safety than traditional carbon anode materials.Furthermore,the thermal behaviors of full cells under abusive conditions are reviewed here.Due to the sensitivity of ARC to the kinetic parameters,a reaction kinetic modeling can be built on the basis of ARC profiles,to predict the thermal behaviors of cell components and cells.Herein,a shortcircuit modeling is exampled.

Low Temperature Heat Capacities and Thermodynamic Properties of Zinc L-Threonate Zn(C_4H_7O_5)_2(s) by Adiabatic Calorimetry

Low-temperature heat capacities of the solid compound Zn（C4H7O5）2（s） were measured in a temperature range from 78 to 374 K, with an automated adiabatic calorimeter. A solid-to-solid phase transition occurred in the temperature range of 295？322 K. The peak temperature, the enthalpy, and entropy of the phase transition were determined to be （316.269±1.039） K, （11.194±0.335） kJ？mol-1, and （35.391±0.654） J？K-1？mol-1, respectively. The experimental values of the molar heat capacities in the temperature regions of 78？295 K and 322？374 K were fitted to two polynomial equations of heat capacities（Cp,m） with reduced temperatures（X） and [X = f（T）], with the help of the least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound, relative to that of the standard reference temperature 293.15 K, were calculated on the basis of the fitted polynomials and tabulated with an interval of 5 K. In addition, the possible mechanism of thermal decomposition of the compound was inferred by the result of TG-DTG analysis.

Determination of Standard Molar Enthalpies of Formation for "White Powdery Tungstic Acid" and for Dodecatungstophosphoric Acid by Solution Calorimetry

'White powdery tungstic acid' has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f of three tungsten- containing acids. The values found for 'white powdery tungstic acid' WO3·1. 68H2O, 'yellow tungstic acid' WO3·1. 20H2O and dodecatungstophosphoric acid H3(PW12O40)·25H2O at 298. 15 K were-(1312±1), - (1192±1) and -(18150±13) kJ mol-1, respectively.

Studies of the Energy Release of Mitochondria from Sporophyte Cytoplasmic Male Sterile Rice by Differential Scanning Calorimetry

The differential scanning calorimetric (DSC)curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70℃. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process.

Measurement of Crystallinity of Acrylic Copolymer by Swelling Differential Scanning Calorimetry

In this paper the measurement of crystallinity(C)ofacrylic copolymer(PAC),by Swelling Differential Scan-ning Calorimetry(SDSC)is discussed.Common DSC isonly used for measuring the crystallinity of polymers withmelting point,(T_m),below their decomposition temper-ature,(T_d).As temperature rises,polymers with swell-ing agent added become swollen and dissolved,goingthrough whole process of breaking solid structures.Thus,SDSC makes it possible to measure the crystallini-ty of polymers even with T_d below T_m.But the C mea-sured by WAXD and the total endothermal melting(swelling)heat in SDSC thermograms,(△H_l),are notlinearly correlated.It has been found that,instead of the△H_l,△H_l’obtained from the △H_l by subtracting the en-dothermal heat,△H_l,and the C measured by WAXDare linearly correlated.On the basis of this linear rela-tion,the unknown C of another PAC sample is measuredby SDSC.The result is in good accordance with thatmeasured by WAXD.

A comparative study on the reactivity of charged Ni-rich and Ni-poor positive electrodes with electrolyte at elevated temperatures using accelerating rate calorimetry

The reactivity between charged Li(Li_(0.115)Mn_(0.529)Ni_(0.339)Al_(0.017))O_(2)(Li-rich),single crystal Li(Ni_(0.8)Mn_(0.1)Co_(0.1))O_(2)(SC-NMC811),LiFePO_(4)(LFP) and LiMn_(0.8)Fe_(0.2)PO_(4)(LMFP) positive electrodes at different states of charge(SOCs) and traditional carbonate-based electrolyte at elevated temperatures is systematically studied using accelerating rate calorimetry(ARC).The results show that the SOC greatly affects the thermal stability of the Li-rich and SC-NMC811 when traditional carbonate-based electrolyte is used.Although an increase in the SOC increases the energy density of lithium-ion cells,it also increases the reactivity between charged Li-rich and SC-NMC811 samples with electrolyte at elevated temperatures.In comparison with SC-NMC811,the Li-rich samples are much more stable at elevated temperatures,and the latter have higher specific capacity.SC-NMC811 samples are less reactive than traditional polycrystalline NMC811.Both LFP and LMFP samples show excellent thermal stability at elevated temperatures.The substitution of Fe by Mn in the olivine series positive materials does not impact the reactivity with electrolyte.