Predictive modeling of critical temperatures in magnesium compounds using transfer learning

This study presents a transfer learning approach for discovering potential Mg-based superconductors utilizing a comprehensive target dataset.Initially,a large source dataset(Bandgap dataset)comprising approximately∼75k compounds is utilized for pretraining,followed by fine-tuning with a smaller Critical Temperature(T_(c))dataset containing∼300 compounds.Comparatively,there is a significant improvement in the performance of the transfer learning model over the traditional deep learning(DL)model in predicting Tc.Subsequently,the transfer learning model is applied to predict the properties of approximately 150k compounds.Predictions are validated computationally using density functional theory(DFT)calculations based on lattice dynamics-related theory.Moreover,to demonstrate the extended predictive capability of the transfer learning model for new materials,a pool of virtual compounds derived from prototype crystal structures from the Materials Project(MP)database is generated.T_(c) predictions are obtained for∼3600 virtual compounds,which underwent screening for electroneutrality and thermodynamic stability.An Extra Trees-based model is trained to utilize E_(hull)values to obtain thermodynamically stable materials,employing a dataset containing Ehull values for approximately 150k materials for training.Materials with Ehull values exceeding 5 meV/atom were filtered out,resulting in a refined list of potential Mg-based superconductors.This study showcases the effectiveness of transfer learning in predicting superconducting properties and highlights its potential for accelerating the discovery of Mg-based materials in the field of superconductivity.

An integrated machine learning model for accurate and robust prediction of superconducting critical temperature

Discovering new superconductors via traditional trial-and-error experimental approaches is apparently a time-consuming process,and the correlations between the critical temperature(Tc) and material features are still obscure.The rise of machine learning(ML) technology provides new opportunities to speed up inefficient exploration processes,and could potentially uncover new hints on the unclear correlations.In this work,we utilize open-source materials data,ML models,and data mining methods to explore the correlation between the chemical features and Tcvalues of superconducting materials.To further improve the prediction accuracy,a new model is created by integrating three basic algorithms,showing an enhanced accuracy with the coefficient of determination(R2) score of 95.9 % and root mean square error(RMSE) of 6.3 K.The average marginal contributions of material features towards Tcvalues are estimated to determine the importance of various features during prediction processes.The results suggest that the range thermal conductivity plays a critical role in Tcprediction among all element features.Furthermore,the integrated ML model is utilized to screen out potential twenty superconducting materials with Tcvalues beyond 50.0 K.This study provides insights towards Tcprediction to accelerate the exploration of potential high-Tcsuperconductors.

Estimation of Critical Temperature of Thermal Explosion for Energetic Materials Based on Non-isothermal Kinetic Equation dα/dt =A_0 exp(bT)[1+(T–T_0 )b]f(α)

Critical temperature（Tb） of thermal explosion for energetic materials is estimated from Semenov＇s thermal explosion theory and the non-isothermal kinetic equation da/dt=Aoexp（bT）[1＋（T-T0）b][（a） deduced via reasonable hypotheses, where To is the initial point of the deviation from the baseline of DSC curve. The final formula is （Tb-Te0）{ 1＋1/[1＋（ Tb-T00）b]}=1. We can easily obtain the initial temperature（T0/） and onset temperature（Tci） from the non-isothermal DSC curves, the values of Too and Tc0 from the equation TOi or ei=T00 or c0＋α1βi＋a2βi^2＋…＋aL-2L-2βiL-2, i=1,2,…L, the value of b from the equation： In[β/（Tei-T0i）]=ln[A0/G（a）]＋bTei, so as to calculate the value of Tb. The result obtained with this method coincides completely with the value of Tb obtained by Hu-Yang-Liang-Wu method.

Estimation of Critical Rate of Temperature Rise for Thermal Explosion of First Order Autocatalytic Decomposition Reaction Systems by Using Non-isothermal DSC

A method of estimating the critical rate of temperature rise for the thermal explosion of first order autocatalytic decomposition reaction systems by using non-isothermal DSC is presented. The information was obtained on the increasing rate of temperature for the first order autocatalytic decomposition of nitrocellulose containing 13.86% nitrogen converting into the thermal explosion.

A Study of Estimating the Safe Storage Life, Self-accelerating Decomposition Temperature and Critical Temperature of Thermal Explosion of Double-base Propellant Using Isothermal and Non-isothermal Decomposition Behaviours

A method of estimating the safe storage life （τ）, self-accelerating decomposition temperature （TsADT） and critical temperature of thermal explosion （Tb） of double-base propellant using isothermal and non-isothermal decomposition behaviours is presented. For double-base propellant composed of 56±1wt% of nitrocellulose （NC）, 27±0.5wt% of nitroglycerine （NG）, 8.15±0.15wt% of dinitrotoluene （DNT）, 2.5±0.1wt% of methyl centralite, 5.0±0.15wt% of catalyst and 1.0±0.1wt% of other, the values of r of 49.4 years at 40℃, of TSAOT of 151.35℃ and of Tb of 163.01℃ were obtained.

Determination of the Critical Temperature and Critical Pressure of Five Compounds

The critical properties of five compounds,including propanal,butanal,1-pentanal,2-methel butanal and trimer of ethanal,were determined for the first time by a new capillary quick-flow method. The apparatus was improved with a capillary tube and checked with hexane and 1-heptene as standard reagents. The experimental results proved that the determination of critical properties by quick-flow method with a capillary tube apparatus was successful.

Estimation of Critical Temperature of Thermal Explosion for Trinitromethyl Explosives by Non-isothermal DSC

Two general expressions and their six derived formulae for estimating the critical temperature（Tb） of thermal explosion for energetic materials（EMs） were derived from the Semenov＇s thermal explosion theory and eight non-isothermal kinetic equations via reasonable hypothesis. We can easily obtain the values of the initial temperature（T0i） at which DSC curve deviates from the baseline of the non-isothermal DSC curve of EMs, the onset temperature（Tei）, the exothermic decomposition reaction kinetic parameters and the values of Too and Te0 from the equation Toiorei=Tooore0＋α1β1＋α2β2＋...＋αL-2βi^L-2, i=1, 2, …, L and then calculate the values of Tb by means of the six derived formulae. The results obtained with the six derived calculating methods for six trinitromethyl explosives： bis（2,2,2- trinitroethyl-N-nitro） ethylene diamine（BTNEDA）, 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate（TNETB）, bis（2,2,2- trinitroethyl） formal（BNTF）, bis（2,2,2-trinitroethyl-nitramine）（BTNNA）, 2,2,2-trinitroethyl-2,2,2-trinitroethyl-N- nitroamino acetate（TNTNNA） and tetrakis [2,2,2-trinitroethyl] orthoester（TTNOE） agree well with each other.

Size Effects of the Critical Temperature in Ferroelectric Thin Films

The size effects of the critical behaviors for the systems of interacting spins are discussed extensively inliterature.In this paper,the finite-size dependence of the critical temperature and susceptibility of the ferroelectric thinfilm are investigated numerically based on the four-state Potts model with the nearest-neighbor interactions between thedipole moments.The four orientations of the domains exist in the ferroelectric film and the movement of the domainwalls determines the polarization switching process besides the boundary conditions of the film.The critical exponentsare obtained and our investigations show that the boundary conditions play the important roles for the ferroelectricproperties of the thin films and the critical behavior of the thin films strongly depends on the feature of the surface.

In-plane shear(ModeⅡ) crack sub-critical propagation of rock at high temperature

In-plane shear crack sub-critical propagation of rock at high temperature was studied by finite element method and shear-box(i.e.compression-shear) test with newly designed electrically conductive adhesive method.Numerical and experimental results show that the normalized shear(Mode Ⅱ) stress intensity factors,K ⅡT/KT0 is decreased as the temperature increases because high temperature can improve stress distribution at crack tip and reduce the Mode Ⅱ stress intensity factor.Microscopic features of fractured surface are of little pits and secondary micro-cracks in the vicinity(1.5-4.0 mm) of the crack tip.The chevron-shape secondary cracks gradually merge in the length of about 4-5 mm and disappear along the direction of crack propagation.Stable shear crack propagation time is increased with the increasing temperature while the stable shear crack propagation rate is decreased with the increasing temperature,since high temperature can increase the shear(Mode Ⅱ) fracture toughness and prevent the crack growth.It is necessary to ensure the ligament of specimen long enough to measure the maximum unstable crack propagation rate of rock.

A comparison of the pitting corrosion resistances of the 304 and new 200 series of stainless steels by potential dependent critical pitting corrosion temperatures

This study researched the relationship between the applied potential and the critical pitting temperature （CPT） of the 304 and new 200 series of stainless steels. The fluctuation about the potential dependent CPT for the stainless steels was investigated and the CPT range was obtained. The difference between the potential dependent CPTs of the 304 and 200 series of stainless steels with an applied potential of 100 mV （ vs SCE）, were presented, and by this means the pitting corrosion resistances of them were compared.

Using the Resistance Depending on the Magnetic and Electric Susceptibility to Derive the Equation of the Critical Temperature

In this study the electromagnetic theory and quantum mechanics are utilized to find the resistivity in terms of electric and magnetic susceptibility in which the electron is considered as a wave. Critical temperature of the wire at which the resistance vanishes is found. In this case the resistance being imaginary which leads the real part of the resistance to real zero at critical temperature and the material becomes super conductor in this case. If one considers the motion of electron in the presence of inner magnetic field and resistance force, a new formula for the conductivity is to be found;this formula states that the material under investigation becomes a superconductor at critical temperature and depends on the strength of the magnetic field and friction resistance, and the substance conductivity is found to be super at all temperatures beyond the critical temperature.

Using the tight binding approximation in deriving the quantum critical temperature superconductivity equation

Superconductivity is one of the most important phenomena in solid state physics. Its theoretical framework at low critical temperature Tc is?based on Bardeen, Cooper and Schrieffer theory (BCS). But at high Tc above 135, this theory suffers from some setbacks. It cannot explain how the resistivity abruptly drops to zero below Tc , besides the explanation of the so called pseudo gap, isotope and pressure effect, in addition to the phase transition from insulating to super-conductivity state. The models proposed to cure this drawback are mainly based on Hubbard model which has a mathematical complex framework. In this work a model based on quantum mechanics besides generalized special relativity and plasma physics. It is utilized to get new modified Schr?dinger equation sensitive to temperature. An expression for quantum resistance is also obtained which shows existence of critical temperature beyond which the resistance drops to zero. It gives an expression which shows the relation between the energy gap and Tc . These expressions are mathematically simple and are in conformity with experimental results.

Improvement in cryosurvival of buffalo bull (Bubalus bubalis) sperm by altering freezing rate within critical temperature range

Objective:To optimize the cryopreservation of buffalo bull semen by altering freezing rates within critical temperature range (4℃ to -60℃). Methods: A total of 20 ejaculates each from 5 Murrah buffalo bulls were cryopreserved using programmable biofreezer in 2 phases. In the 1st phase, 9 freezing rates were applied at -2, -5, -10, -20, -30, -40, -50, -60 or -4℃/min (control) from 4℃ to -15℃;at -40℃/min from -15℃ to -60℃. In the 2nd phase, a fixed freezing rate was applied at -30℃/min from 4℃ to -15℃. Six freezing rates were applied at -10, -20, -30, -40 (control), -50 or -60℃/min from -15℃ to -60℃. The freezing from -60℃ to -140℃ were fixed at -50℃/min in both the phases. Post thaw semen quality was assessed in terms of motility, viability, membrane integrity (hypo-osmotic swelling test), sperm abnormalities, and active mitochondria. Data were arc sine transformed and analyzed through one-way analysis of variance using SPSS software. Results: In the 1st phase, percent individual motility, progressive motility and viability were similar among various protocols. Percent hypo-osmotic swelling reactive sperm was higher with freezing at -30℃/min. In the 2nd phase, percent individual motility, viability and hypo-osmotic swelling reactive sperm was higher with freezing at -50℃/min. Sperm head abnormalities were lower at -30℃/min in the 1st phase, but were similar among the protocols of the 2nd phase. Percent active mitochondria were higher at -30℃/min in the 1st phase and at -50℃/min in the 2nd phase.Conclusions:The optimum post thaw semen quality of buffalo bull could be obtained by applying freezing rate at -30℃/min (4℃ to -15℃) and at -50℃/min (-15℃ to -140℃), followed by plunging of straws in into liquid nitrogen for storage.

A Fermi Energy-Incorporated Framework for Dealing with the Temperature- and Magnetic Field-Dependent Critical Current Densities of Superconductors and Its Application to Bi-2212

It is well known that the critical current density of a superconductor depends on its size, shape, nature of doping and the manner of preparation. It is suggested here that the collective effect of such differences for different samples of the same superconductor is to endow them with different values of the Fermi energy—a single property to which may be attributed the observed variation in their critical current densities. The study reported here extends our earlier work concerned with the generalized BCS equations [Malik, G.P. (2010) Physica B, 405, 3475-3481;Malik, G.P. (2013) WJCMP, 3,103-110]. We develop here for the first time a framework of microscopic equations that incorporates all of the following parameters of a superconductor: temperature, momentum of Cooper pairs, Fermi energy, applied magnetic field and critical current density. As an application of this framework, we address the different values of critical current densities of Bi-2212 for non-zero values of temperature and applied magnetic field that have been reported in the literature.

STUDY ON AUSTENITE-FERRITE TRANSFORMATION WITHIN CRITICAL TEMPERATURE REGION

his paper deals with the phase trans formation of austenite to ferrite within the critical temperature region(between Ac1 and Ac3).The results show that the volume fraction of trans formation of ferrite formed isothermally from austenite is mainly varied with the austenitizing temperature.The higher the austenitizing temperature,the more volume fraction of the ferrite formed isothermally from austenite.Besides,the phase trans formation of austenite to ferrite within the critical temperature region was checked by austenitizing isothermal time.The volume fraction of ferrite formed isothermally from austenite within the critical temperature region for different isothermal time has heen examined experimen tally.The lglg(l-fv)-1 vs lgt relation does not follow the Avrami equation strictly and consists of two straight lines.

A Dynamical Approach to the Explanation of the Upper Critical Field Data of Compressed H3S

Excellent fits were obtained by Talantsev (MPLB 33, 1950195, 2019) to the temperature (T)-dependent upper critical field (Hc2(T)) data of H3S reported by Mozaffari et al. [Nature Communications 10, 2522 (2019)] by employing four alternative phenomenological models, each of which invoked two or more properties from its sample-specific set S1 = {Tc, gap, coherence length, penetration depth, jump in sp.ht.} and a single value of the effective mass (m*) of an electron. Based on the premise that the variation of Hc2(T) is due to the variation of the chemical potential μ(T), we report here fits to the same data by employing a T-, μ- and m*-dependent equation for Hc2(T) and three models of μ(T), viz. the linear, the parabolic and the concave-upward model. For temperatures up to which the data are available, each of these provides a good fit. However, for lower values of T, their predictions differ. Notably, the predicted values of Hc2(0) are much higher than in any of the models dealt with by Talantsev. In sum, we show here that the addressed data are explicable in a framework comprising the set S2 = {μ, m*, interaction parameter λm, Landau index NL}, which is altogether different from S1.

基于概率回归和信息扩散理论的南充晚熟柑橘低温冻害指标体系研究

低温冻害是南充市晚熟柑橘的主要灾害,本研究旨在建立一套低温冻害指标体系,以减少南充市晚熟柑橘因低温冻害而造成的损失。通过分析农业部门提供的冻害实验数据和历史灾情记录,并结合国家气象监测站的小时气温数据,在满足特定气候条件(冬季天空无云或少云,日温差大于等于8℃,最低气温小于等于3℃)的基础上,运用概率回归和信息扩散理论方法对低温冻害指标阈值进行研究。结果发现,两个实验果园中气象温度与实测温度的线性回归关系显著,且通过统计检验。具体为当气象温度为西充1.7℃和嘉陵2.6℃时,相应果园的实测温度将至-2℃,开始出现冻害现象。根据目前精细化天气预测能力,研究构建了一个基于两周滑动时段的复合指标阈值体系,该体系包括低温冻害日最长持续时间、总持续时间和总天数3个指标。通过对4个冻害样本的检验,结果显示冻害指标评级与实际观测到的冻害等级高度一致,证明了该冻害指标体系具有较好的实际应用价值。

温湿度联合作用下软岩粗粒料三轴剪切力学特性研究

软岩粗粒料具有风化程度高、易破碎等特点,其力学特性易受温湿环境的影响。利用自主研制的温湿控制粗粒料大型三轴仪开展了一系列控制温湿度的软岩粗粒料三轴剪切试验,探究了温湿度对软岩粗粒料剪切强度、剪切变形、颗粒破碎及临界状态的影响规律。研究发现:(1)软岩粗粒料的力学行为受温湿度影响显著,随着温湿度的升高,其峰值剪切强度降低,剪缩变形量增加,颗粒破碎程度增大,p-q空间内的临界状态线向下旋转,同时e-(p/pa)^(ξ)空间内的临界状态线向下平移;(2)温湿度对力学特性的影响在低围压条件下更显著,随着围压的升高,温湿度引起的差异性变小。(3)基于不同温湿度作用下的颗粒破碎等效对应关系,实现了不同温湿工况下颗粒破碎及临界状态试验规律的归一化,为建立统一考虑温湿度影响的本构模型提供思路。

Al改性MgB_(2)材料与金属界面特性及其超导性能研究

针对MgB_(2)超导材料用于液氢液位传感器的临界转变温度与液氢液化温度差异大和原始粉末与金属护套界面反应导致测量控制难的问题,研究了降低MgB_(2)临界转变温度的改性技术,以及改性后粉末与金属护套Fe、Monel反应产物及退火温度对其超导转变宽度的影响。结果表明,当掺杂量x=0.15时,Mg_(1-x)Al_xB_(2)多晶样品的临界转变温度为30 K左右,满足液氢液位传感器使用环境。金属护套Fe、Monel与前驱体粉末Mg、Al之间都有不同程度的扩散界面发生,Fe金属护套样品扩散层厚度较小,大约为25μm,更适合于Al掺杂MgB2超导线材的制备护套材料。不同退火温度下的带金属护套的Fe、Monel改性MgB_(2)样品仍具有明显的超导转变,且超导转变温度满足液氢液位计使用环境。