Effect of heat treatment on microstructure, mechanical properties and in vitro degradation behavior of as-extruded Mg-2.7Nd-0.2Zn-0.4Zr alloy

Mg-2.7Nd-0.2Zn-0.4Zr （mass fraction, %） alloy was designed for degradable biomedical material. The ingots of the alloy were solution treated and then hot extruded. The extruded rods were heat treated with aging treatment, solution treatment and solution＋aging treatment, respectively. Microstructures of the alloy were observed by optical microscopy （OM） and scanning electron microscopy （SEM）. Mechanical properties at room temperature were tested. In vitro degradation behavior of the alloy immersed in simulated body fluid was measured by hydrogen evolution and mass loss tests. The degradation morphologies of the alloy with and without degradation products were observed by SEM. The results show that the grains grow apparently after solution treatment. Solution treatment improves the elongation of as-extruded alloy significantly and decreases the strength, while aging treatment improves the strength and reduces the elongation of the alloy. The yield ratio is reduced by heat treatment. The in vitro degradation results of the alloy show that solution treatment on the as-extruded alloy results in a little higher degradation rate and aging treatment on the alloy can reduce degradation rate slightly.

Simulation and Analysis of Cascading Faults in Integrated Heat and Electricity Systems Considering Degradation Characteristics

Cascading faults have been identified as the primary cause of multiple power outages in recent years.With the emergence of integrated energy systems(IES),the conventional approach to analyzing power grid cascading faults is no longer appropriate.A cascading fault analysis method considering multi-energy coupling characteristics is of vital importance.In this study,an innovative analysis method for cascading faults in integrated heat and electricity systems(IHES)is proposed.It considers the degradation characteristics of transmission and energy supply com-ponents in the system to address the impact of component aging on cascading faults.Firstly,degradation models for the current carrying capacity of transmission lines,the water carrying capacity and insulation performance of thermal pipelines,as well as the performance of energy supply equipment during aging,are developed.Secondly,a simulation process for cascading faults in the IHES is proposed.It utilizes an overload-dominated development model to predict the propagation path of cascading faults while also considering network islanding,electric-heating rescheduling,and load shedding.The propagation of cascading faults is reflected in the form of fault chains.Finally,the results of cascading faults under different aging levels are analyzed through numerical examples,thereby verifying the effectiveness and rationality of the proposed model and method.

Reduction in Activity/Gene Expression of Anthocyanin Degradation Enzymes in Lychee Pericarp is Responsible for the Color Protection of the Fruit by Heat and Acid Treatment

Heat and acid treatments were reported to be a promising substitute for SO2 fumigation in color protection of postharvest lychee （Litchi chinensis） fruits, but the mechanism was not clear. In the present study, hot water （70℃） dipping followed by immersion in 2% HC1 （heat-acid） substantially protected the red color of the fruit during storage at 25℃ and inhibited anthocyanin degradation while hot water dipping alone （heat） led to rapidly browning and about 90% loss in anthocyanin content. The pH values in the pericarp of the heat-acid treated fruit dropped to 3.2, while the values maintained around 5.0 in the heat-treated and control fruit. No significantly different pH values were detected among the arils of heat-acid, heat treated and control fruit. Heat-acid treatment dramatically reduced the activities of anthocyanin degradation enzyme （ADE）, peroxidase （POD） and polyphenol oxidase in the pericarp. A marked reduction in LcPOD gene expression was also detected in heat-acid treated fruit, in contrast, induction was found in heat treated fruit. The pericarp of heat-acid treated fruit exhibited significantly lower respiration rate but faster water loss than that of the untreated or heat treated fruit. Taken together, heat treatment triggered quick browning and anthocyanin loss in lychee fruit, while heat-acid treatment protected the fruit color by a great reduction in the activities/gene expression of anthocyanin degradation enzymes and acidification of lychee pericarp.

Analytical solution for the time-fractional heat conduction equation in spherical coordinate system by the method of variable separation

In this paper,using the fractional Fourier law,we obtain the fractional heat conduction equation with a time-fractional derivative in the spherical coordinate system.The method of variable separation is used to solve the timefractional heat conduction equation.The Caputo fractional derivative of the order 0 〈 α≤ 1 is used.The solution is presented in terms of the Mittag-Leffler functions.Numerical results are illustrated graphically for various values of fractional derivative.

Polymorphism of heat shock protein 70-2 and enterocutaneous fistula in Chinese population

AIM: To investigate whether the heat shock protein 70-2 (HSP70-2) polymorphism is associated with enterocutaneous fistulas in a Chinese population.

STUDY OF DEGRADATION MECHANISM AND PACKAGING OF ORGANIC LIGHT EMITTING DEVICES

Organic Light Emitting Devices (OLED) have attracted much attention recently, for their applications in futureFlat Panel Displays and lighting products. However, their fast degradation remained a major obstacle to theircommercialization. Here we present a brief summary of our studies on both extrinsic and intrinsic causes for the fastdegradation of OLEDs. In particular, we focus on the origin of the dark spots by 'rebuilding' cathodes, which confirms thatthe growth of dark spots occurs primarily due to cathode delamination. In the meantime, we recapture the findings from thesearch for suitable OLED packaging materials, in particular polymer composites, which provide both heat dissipation andmoisture resistance, in addition to electrical insulation.

A Study on Modifying the Calculation Model of Valid Opening Size of Heat-bonded Nonwoven Fabrics

It has been found that there are marked errors in the value of valid opening size of heat-bonded nonwoven fabrics between theoretical calculations and engineering measurements. A new modified theoretical model is advanced in this paper. The equivalent diameter of the pore of a fibre web is used to calculate the valid opening size instead of the maximum diameter of inscribed circle used, because the fibres in practical fibre webs are flexible elastomers with definite diameters and the pore of fibre web may produce deformation in screening teat and engineering usage. The results show that the theoretical calculations coincide well with the engineering measurements. This method offers a theoretical basis for computer simulation to the performance of filters of heatbonded nonwoven fabrics.

Heat Capacities and Thermodynamic Properties of 3-(2,2-Dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic Acid

The heat capacities of 3-（ 2,2-dichloroethenyl）-2,2-dimethylcyclopropanecarboxylic acid （a racemic mixture, molar ratio of cis-/trans-structure is 35/65） in a temperature range from 78 to 389 K were measured with a precise automatic adiabatic calorimeter. The sample was prepared with a purity of 98.75% （ molar fraction）. A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, Tm, enthalpy and en- tropy of fusion, △fusHm, △fusSm, of the acid were determined to be （331.48±0.03 ） K, （16.321±0.031） kJ/mol, and （49.24±0.19） J/（ K·mol）, respectively. The thermodynamic functions of the sample, Ht-H298.15, Sr-S298.15 and Gr-G298.15, were reported at a temperature intervals of 5 K. The thermal decomposition of the sample was studied using thermogravimetric（TG） analytic technique, the thermal decomposition starts at ca. 418 K and ends at ca. 544 K, the maximum decomposition rate was obtained at 510 K. The order of reaction, preexponential factor and activation energy are n =0.23, A =7.3 ×10^7 min^-1 , E =70.64 kJ/mol, respectively.

Study on the Factors to Influence Dynamic Heat - moisture Comfort of Summer Clothing Fabrics

In this paper, the factors to influence the dynamic heat - moisture comfort of summer clothing fabrics have been studied. It is pointed out that, when the wind speed outside is high, or the air permeability is very good, the sweat of human body will evaporate mainly through turbulent diffusion. Because of the rapid sweat evaporation, human body will feel cold, and then, the difference in temperature and humidity of the micro - climatic section will be very slight. On the contrary, when the wind speed outside is slow or the air permeability is unsatisfactory, the sweat of human body will evaporate mainly through molecular diffusion, and in this case, the humidity of the micro - climatic section will be depended on the hygroscopicity of the fabric, that’ s to say, the better the hygroscopicity, the lower the humidity. It is difficult for pure wool fabric to loss heat because of its giving out much heat during the course of moisture - absorption in the initial stages of sweating. For pure polyester fabric,

A Compact Difference Scheme for Multi-point Boundary Value Problems of Heat Equations

In this paper,a compact difference scheme is established for the heat equations with multi-point boundary value conditions.The truncation error of the difference scheme is O(τ2+h^4),where t and h are the temporal step size and the spatial step size.A prior estimate of the difference solution in a weighted norm is obtained.The unique solvability,stability and convergence of the difference scheme are proved by the energy method.The theoretical statements for the solution of the difference scheme are supported by numerical examples.

Effect of Heat Treatment on Mechanical Properties and Microstructure of NST 37-2 Steel

Engineering materials, mostly steel, are heat treated under controlled sequence of heating and cooling to alter their physical and mechanical properties to meet desired engineering applications. In this study, the effect of heat treatment (annealing, normalising, hardening, and tempering) on the microstructure and some selected mechanical properties of NST 37-2 steel were studied. Sample of steel was purchased from local market and the spectrometry analysis was carried out. The steel samples were heat treated in an electric furnace at different temperature levels and holding times;and then cooled in different media. The mechanical properties (tensile yield strength, ultimate tensile strength, Young’s modulus, percentage reduction, percentage elongation, toughness and hardness) of the treated and untreated samples were determined using standard methods and the microstructure of the samples was examined using metallographic microscope equipped with camera. Results showed that the mechanical properties of NST 37-2 steel can be changed and improved by various heat treatments for a particular application. It was also found that the annealed samples with mainly ferrite structure gave the lowest tensile strength and hardness value and highest ductility and toughness value while hardened sample which comprise martensite gave the highest tensile strength and hardness value and lowest ductility and toughness value.

Heat Treatment of Nd_(1+x)Ba_(2-x)Cu_3O_(7-δ) Superconductors

Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- x Cu 3O 7- δ before and after the heat treatment was investigated by XRD. In order to know the effects of heat treatment, the T c and J c of samples with and without the heat treatment in Ar were comparatively studied. The results show that the substitution of Nd for Ba decreases, whereas T c and J c increase after the treatment. The Nd 1+ x Ba 2- x Cu 3O 7- δ samples were oxygenated in pure oxygen at 300 ℃ . Based on the XRD spectra it was found that the samples with x <0.4 can transform from tetragonal phase into orthorhombic phase after the oxygenation, whereas in the sample with x >0.4 no phase transition occurs even after a long time oxygenation.

Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C_8H_(11)NO)

This paper reports that low-temperature heat capacities of 4-（2-aminoethyl）-phenol （C8H11NO） are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15K were calculated and tabulated at the interval of 5K. The energy equivalent, εcalor, of the oxygen-bomb combustion calorimeter has been determined from 0.68g of NIST 39i benzoic acid to be εcalor=（14674.69±17.49）J·K^-1. The constant-volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ΔcU=-（32374.25±12.93）J·g^-1. The standard molar enthalpy of combustion for the compound was calculated to be ΔcHm = -（4445.47 ± 1.77） kJ·mol^-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ΔfHm（C8H11NO, s）=-（274.68 ±2.06） kJ·mol^-1, in accordance with Hess law.

Corrosion Resistance of Heat-Treated NST 37-2 Steel in Hydrochloric Acid Solution

Corrosion of metal components constitutes a major challenge in many engineering systems, with appropriate design, proper material selection, and heat treatment as commonly used control strategies. In this study, the corrosion behaviour of heat-treated (annealed, normalised, hardened, and tempered) NST 37-2 steel in three concentrations (1.0, 1.5 and 2.0 M) of hydrochloric acid solution was investigated using weight loss and electrode-potential methods. Results showed that corrosion rate increased with increase in acid concentration. The decreasing order of corrosion resistance was Tempered > Annealed > Normalised > Hardened > Untreated. The surface pictures of the heat-treated and untreated samples showed uniform and pitting corrosion with the latter becoming more pronounced as concentration increased.

Molar heat capacities of La_2Mo_2O_9 and La_(1.9)Sr_(0.1)Mo_2O_(9-δ)

The molar heat capacities of La2Mo209 and La1.9Sr0.1MO209-δ were obtained using the differential scanning calorimetry （DSC） technique in a temperature range from 298 to 1473 K. The DSC curve of La2Mo209 showed an endothermal peak around 834 K corresponding to a first-order monoclinic-cubic phase transition, and the enthalpy change accompanying this phase transition is 5.99 kJ/mol. No evident endothermal peak existed in the DSC curve of La1.9Sr0.1MO209-δ, but a broad thermal anomaly existed in its heat capacity curve at around 832 K. In addition, the heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ began to decrease at 1196 and 1330 K, respectively. The non-transitional heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ were formulated using multiple regression analysis in two temperature ranges.

A Novel Degradation Pathway of Zn(dmid)(phen)_2 in Pyridine

The light-oxidation degradation processes of Zn(dmid)(phen)_2 ( dmid = 4,5-dimercapto-l, 3-dithiole-2-one, phen = 1,10-phenanthroaline) in pyridine solvent has beenmonitored. It has been found under the light, dmid^(2-) of Zn(dmid)-(phen)_2 in pyridine solutioncould generate NCS~ and NCS^-replaces dmid^(2-) to form Zn(NCS)_2 (phen)_2 simultaneously. Thecrystal structure of Zn(NCS)_2 (phen)_2 has been determined. In the crystal of Zn(NCS)_2 (phen)_2,two NCS~ ligands are arranged in syn-configuration, and there is strong pi-pi interaction betweenthe two adjacent parallel phen.

N-苯基马来酰亚胺、苯乙烯和马来酸酐三元共聚及热分解动力学

合成了N-苯基马来酰亚胺、苯乙烯和马来酸酐三元共聚物,采用红外光谱法对其结构进行了表征,并利用TG,DTG和DSC热分析技术对该共聚物的耐热性能及热分解动力学进行了分析,探讨了其热分解机理.结果表明:该共聚物的热分解受单机理控制,初始热分解温度为637K;683K后热分解速率迅速增大,703K时达到最大,在761K时分解基本结束;共聚物在氮气中失重20%和50%时的温度分别为679K和700K,玻璃化转变温度为485 K;根据K issinger法求得非等温条件下共聚物热分解的表观活化能为173.21 kJ/mol,指前因子为3.293 9×1012m in-1,由Crane法求得其反应级数为0.94.

15CrMo耐热钢Larson-Miller参数值的确定与应用

通过对已有文献资料的综合与分析处理,确定了珠光体型耐热钢15CrMo的Larson Miller(P)参数中的C值,并用以描述15CrMo的高温行为和性能,包括合金元素的贫化、蠕变强度和持久强度以及硬度的变化.并且进而用于15CrMo锅炉管道的寿命分析和剩余寿命的预测.

热休克蛋白65及其融合蛋白Hsp65-6×P277的分离纯化和稳定性研究(英文)

来源于牛分枝杆菌的热休克蛋白65(Hsp65)在没有佐剂的情况下可作为载体分子将抗原表位递呈给免疫系统。热休克蛋白具有蛋白酶的催化活性,容易发生自溶而降解,这制约了基于Hsp65疫苗的研究。该研究中,建立了纯化Hsp65及其融合蛋白Hsp65-6×P277(P277为来源于人热休克蛋白60的肽段,线性重复6次)的方法。Hsp65与Hsp65-6×P277以可溶形式表达于大肠杆菌。在低温及添加EDTA的条件下经细胞裂解、硫酸铵沉淀及阴离子交换树脂等纯化方法,可得到电泳纯的目的蛋白。用纯化的融合蛋白Hsp65-6×P277免疫小鼠,可激发机体产生强烈的免疫应答,该融合蛋白有希望作为免佐剂的糖尿病疫苗加以进一步研究开发。

植物纤维素在微波-HCl／H2O2耦合条件下降解工艺条件的优化

在微波加热条件下,研究降解条件(催化剂体积分数、反应温度、时间)对植物纤维素降解过程的影响,结果表明,适宜降解条件为:φ催化剂=5%,100℃反应2 h.在此条件下,得到的ρ还原糖=2.15 g/L,微波加热降解较常规加热还原糖浓度提高了33.5%,降解率提高了48.7%.利用SEM分析微波降解和常规条件下降解产物的结构特征,结果表明,微波作用下使纤维素的聚合度降低.红外分析结果表明,微波条件与常规条件下的剩余物结构一致.