Overexpression of Kdm6b induces testicular differentiation in a temperature-dependent sex determination system

In reptiles,such as the red-eared slider turtle(Trachemys scripta elegans),gonadal sex determination is highly dependent on the environmental temperature during embryonic stages.This complex process,which leads to differentiation into either testes or ovaries,is governed by the finely tuned expression of upstream genes,notably the testis-promoting gene Dmrt1 and the ovary-promoting gene Foxl2.Recent studies have identified epigenetic regulation as a crucial factor in testis development,with the H3K27me3 demethylase KDM6B being essential for Dmrt1 expression in T.s.elegans.However,whether KDM6B alone can induce testicular differentiation remains unclear.In this study,we found that overexpression of Kdm6b in T.s.elegans embryos induced the male development pathway,accompanied by a rapid increase in the gonadal expression of Dmrt1 at 31°C,a temperature typically resulting in female development.Notably,this sex reversal could be entirely rescued by Dmrt1 knockdown.These findings demonstrate that Kdm6b is sufficient for commitment to the male pathway,underscoring its role as a critical epigenetic regulator in the sex determination of the red-eared slider turtle.

基于FTIR的黄芪药材质量评价研究

目的 建立黄芪药材的红外原始指纹图谱与量子指纹图谱,为其质量控制提供参考。方法 采用傅里叶变换红外光谱仪采集35批黄芪药材的红外指纹图谱,经数据处理建立黄芪的红外量子指纹图谱,采用系统指纹定量法以及t检验比较两种指纹图谱是否存在差异,并对量子指纹图谱的共有量子峰面积进行系统聚类分析。结果 黄芪药材的红外指纹图谱与量子指纹图谱间并不存在显著性差异,系统指纹定量法将35批黄芪分为8个质量等级,系统聚类分析表明35批黄芪的质量可聚为两类。结论 红外量子指纹图谱能够提供大量特征信息,系统指纹定量法能够全面、准确、直观地将黄芪药材分为8个质量等级,两者结合可以实现对黄芪等中药材质量的全面评价。

Temperature-Dependent Debye Temperature and Specific Capacity of Graphene

The shot-range interaction and the atomic anharmonic vibration are both considered, and then the analytic functions of the Debye temperature, the specific capacity and the thermal conductivity of graphene with the temperature are obtained. The influence of anharmonic vibration on these thermal physical properties is also investigated. Some theoretical results are given. If only the harmonic approximation is considered, the Debye temperature of the graphene is unrelated to the temperature. If the anharmonic terms are considered, it increases slowly with the increasing temperature. The molar heat capacity of the graphene increases nonlinearly with the increasing temperature. The mean free path of phonons and the thermal conductivity of the graphene decrease nonlinearly with the increasing temperature. The relative changes of the Debye temperature, the specific heat capacity and the thermal conductivity caused by the anharmonic terms increase with the increasing temperature. The anharmonic effect of atomic vibration becomes more significant under higher temperature.

Temperature-dependent photoluminescence on organic inorganic metal halide perovskite CH_3NH_3Pb I_(3-)Cl_ prepared on ZnO/FTO substrates using a two-step method

Temperature-dependent photoluminescence characteristics of organic-inorganic halide perovskite CH3NH3Pb I3-xClx films prepared using a two-step method on ZnO/FTO substrates were investigated. Surface morphology and absorption characteristics of the films were also studied. Scanning electron microscopy revealed large crystals and substrate coverage. The orthorhombic-to-tetragonal phase transition temperature was-140 K. The films＇ exciton binding energy was 77.6 ± 10.9 meV and the energy of optical phonons was 38.8 ± 2.5 meV. These results suggest that perovskite CH3NH3Pb I（3-x）Clx films have excellent optoelectronic characteristics which further suggests their potential usage in perovskitebased optoelectronic devices.

Transient thermal behavior of radial fins of rectangular,triangular and hyperbolic profiles with temperature-dependent properties using DTM-FDM

This work focuses on transient thermal behavior of radial fins of rectangular,triangular and hyperbolic profiles with temperature-dependent properties.A hybrid numerical algorithm which combines differential transformation(DTM) and finite difference(FDM) methods is utilized to theoretically study the present problem.DTM and FDM are applied to the time and space domains of the problem,respectively.The accuracy of this method solution is checked against the numerical solution.Then,the effects of some applicable parameters were studied comparatively.Since a broad range of governing parameters are investigated,the results could be useful in a number of industrial and engineering applications.

Temperature-dependent photoluminescence of highly luminescent water-soluble CdTe quantum dots

Highly luminescent water-soluble CdTe quantum dots （QDs） have been synthesized with an electrogenerated precursor. The obtained CdTe QDs can possess good crystallizability, high quantum yield （QY） and favorable stability. Furthermore, a detection system is designed firstly for the investigation of the temperature-dependent PL of the QDs. ？2009 Yu Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Elasticity solution of laminated beams with temperature-dependent material properties under a combination of uniform thermo-load and mechanical loads

An exact solution for simply-supported laminated beams with material properties variable with temperature under a combination of uniform thermo-load and mechanical loads was investigated,based on the two-dimensional(2-D)thermo-elasticity theory.Firstly,the beam was divided into a series of layers with uniform material properties along the interfaces of the beam.The uniform thermo-load acted on each layer was transformed into a combination of the normal surface forces acted at the two ends and the transverse thermo-load.Secondly,the state space method was employed to obtain the general solutions of displacements and stresses in an arbitrary layer.Thirdly,based on the interfacial continuity conditions between adjacent layers,the relations of displacement and stress components between the top and bottom layers of the beam were recursively derived by use of the transfer-matrix method.The unknowns in the solutions can be solved by the mechanical loads acted on the top and bottom surfaces.The convergence of the present solutions was checked.The comparative study of the present solutions with the Timoshenko’s solutions and the finite element(FE)solutions was carried out.The effects of material properties variable with temperature on the thermo-elastic behavior of laminated beams were discussed in detail.

Observation of hopping transitions for delocalized electrons by temperature-dependent conductance in silicon junctionless nanowire transistors

We demonstrate transitions of hopping behaviors for delocalized electrons through the discrete dopant-induced quantum dots in n-doped silicon junctionless nanowire transistors by the temperature-dependent conductance characteristics.There are two obvious transition platforms within the critical temperature regimes for the experimental conductance data,which are extracted from the unified transfer characteristics for different temperatures at the gate voltage positions of the initial transconductance gm peak in Vg1 and valley in Vg2. The crossover temperatures of the electron hopping behaviors are analytically determined by the temperature-dependent conductance at the gate voltages Vg1 and Vg2. This finding provides essential evidence for the hopping electron behaviors under the influence of thermal activation and long-range Coulomb interaction.

Effects of temperature-dependent viscosity variation on entropy generation, heat and fluid flow through a porous-saturated duct of rectangular cross-section

Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of Kays and Crawford [12], is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio （width to height ratio）. These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case by Ratts and Rant [14].

Temperature-Dependent Photoluminescence from GaN/Si Nanoporous Pillar Array

A GaN/Si nanoheterostructure is prepared by growing wurtzite GaN on a silicon nanoporous pillar array （Si-NPA） with a chemical vapor deposition method. The temperature evolution of the photoluminescence （PL） of GaN/Si- NPA is measured and the PL mechanism is analyzed. It is found that the PL spectrum is basically composed of two narrow ultraviolet peaks and a broad blue peak, corresponding to the near band-edge emission of GaN and its phonon replicas, and the emission from Si-NPA. No GaN defect-related PL is observed in the as-prepared GaN/Si-NPA. Our experiments prove that Si-NPA might be an ideal substrate for preparing high-quality Si-based GaN nanomaterials or nanodeviees.

Temperature-Dependent Photoluminescence Analysis of 1.0 MeV Electron Irradiation-Induced Nonradiative Recombination Centers in n＋-p GaAs Middle Cell of GaInP/GaAs/Ge Triple-Junction Solar Cells

The effects of irradiation of 1.0 MeV electrons on the n＋-p GaAs middle cell of GalnP/GaAs/Ge triple-junction solar cells are investigated by temperature-dependent photoluminescence （PL） measurements in the 10-300K temperature range. The appearance of thermal quenching of the PL intensity with increasing temperature confirms the presence of a nonradiative recombination center in the cell after the electron irradiation, and the thermal activation energy of the center is determined using the Arrhenius plot of the PL intensity. Furthermore, by comparing the thermal activation and the ionization energies of the defects, the nonradiative recombination center in the n＋ p GaAs middle cell acting as a primary defect is identified as the E5 electron trap located at Ec - 0.96 eV.

The Effect of the Cyp19a1 Gene Methylation Modification on Temperature-dependent Sex Determination of Reeves' Turtle(Mauremys reevesii)

Temperature-dependent sex determination（TSD） is a type of environmental sex determination in which the sex of the embryos depends on the ambient temperature; however,the molecular mechanisms governing this process remain unknown.Aromatase,encoded by the cyp19a1 gene,which converts androgens into estrogens in animals,was considered to be the key gene for TSD.In this study,the 5＇-flanking region of the cyp19a1 gene in Reeves＇ turtle（Mauremys reevesii） was cloned,and the promoter region was identified using the luciferase reporter assay.Then the eggs of Reeves＇ turtle were incubated at different temperatures（26°C： male-biased temperature; 29°C： non-sex-biased temperature and 32°C： female-biased temperature）.During the thermosensitive period,the adrenal kidney gonad complexes（AKG） were sampled.DNA methylation analysis of the AKG samples showed that the promoter region of the cyp19a1 gene was significantly de-methylated in the female-biased temperature regime（P＆lt;0.01）.Quantitative analysis of the cyp19a1 gene and estrogen by q PCR and Elisa assay showed that the expression level of the cyp19a1 gene and estrogen content were both upregulated significantly at the female-biased temperature（P＆lt;0.01）.These results indicated that the de-methylation response of the cyp19a1 gene to incubation temperature,especially at the female-biased temperature,could lead to temperature-specific expression of aromatase and increased estrogen levels,which may further determine gonadal development in Reeves＇ turtle.These findings provide insights into the genetic mechanisms underlying TSD.

A Mathematical Model to Solve Bio-Heat Transfer Problems through a Bio-Heat Transfer Equation with Quadratic Temperature-Dependent Blood Perfusion under a Constant Spatial Heating on Skin Surface

We consider the one-dimensional bio-heat transfer equation with quadratic temperature-dependent blood perfusion, which governs the temperature distribution inside biological tissues. Using an extended mapping method with symbolic computation, we obtain the exact analytical thermal traveling wave solution, which describes the non-uniform temperature distribution inside the bodies. The found exact solution is used to investigate the temperature distribution in the tissues. It is found that the surrounding medium with higher temperature does not necessarily imply that the tissue will quickly (after a short duration of heating process) reach the desired temperature. It is also found that increased perfusion causes a decline in local temperature.

Extended Generalized Riccati Equation Mapping for Thermal Traveling-Wave Distribution in Biological Tissues through a Bio-Heat Transfer Model with Linear/Quadratic Temperature-Dependent Blood Perfusion

Analytical thermal traveling-wave distribution in biological tissues through a bio-heat transfer (BHT) model with linear/quadratic temperature-dependent blood perfusion is discussed in this paper. Using the extended generalized Riccati equation mapping method, we find analytical traveling wave solutions of the considered BHT equation. All the travelling wave solutions obtained have been used to explicitly investigate the effect of linear and quadratic coefficients of temperature dependence on temperature distribution in tissues. We found that the parameter of the nonlinear superposition formula for Riccati can be used to control the temperature of living tissues. Our results prove that the extended generalized Riccati equation mapping method is a powerful tool for investigating thermal traveling-wave distribution in biological tissues.

基于Zeta电位和FTIR的中高阶煤与天然焦表面电性研究

通过对中高阶煤与天然焦表面电性的研究,可为揭示煤与天然焦电磁辐射机理,判断矿物可浮性和实现不同矿物分离提供基础。为深入了解中高阶煤与天然焦表面电性的差异,分析煤与天然焦表面官能团组成的差异,采用Zeta电位与FTIR分析方法对样品的表面特性进行综合分析,研究其表面电性与主要官能团的耦合关系。结果表明:①煤样的Zeta电位总体为负,天然焦样品的Zeta电位为正,同时随着变质程度的升高,样品表面负电官能团减少,Zeta电位增大;②脱灰后,样品表面负电官能团被破坏,煤与天然焦的Zeta电位均为正,且随着煤变质程度的增加,Zeta电位值减小;③羟基、COOH、C=O是影响Zeta电位的主要官能团,其中,C=O对Zeta电位的影响大于COOH;羟基-π是羟基结构中影响Zeta电位的主要官能团。研究成果为进一步探究煤与天然焦电磁辐射机理与浮选性提供基础。

环保绝缘介质C_(6)F_(12)O混合气体FTIR检测技术研究

环保绝缘介质C_(6)F_(12)O混合气体具有应用于中低压设备的潜力,因此C_(6)F_(12)O混合气体检测技术的研究具有非常重要的现实意义。文中基于红外吸收光谱提出了C_(6)F_(12)O混合气体定性定量检测技术。基于密度泛函理论,对C_(6)F_(12)O分子进行结构优化,仿真计算其振动频谱,与实验检测红外光谱进行对比。对体积分数标定模型的波段和特征量的选取进行了详细的研究,提出C_(6)F_(12)O混合气体相关绝缘设备的混合比和微量体积分数检测方案。结果表明,红外光谱的仿真结果与实验结果具有较好的一致性;不同体积分数的吸收峰有很好的线性关系,利用峰值作为特征值比峰面积建立的体积分数标定模型准确性和稳定性强。混合比检测时,以3 500~3 567 cm^(-1)波段的峰值作特征量建立模型的拟合度为0.999 57,检测误差在2%以内;微量检测时,以1 750~1 820 cm^(-1)波段的峰值作特征量建立模型的拟合度高达0.999 97,检测误差小于3.8%,建立的体积分数标定模型的稳定性、准确性较好。文中研究结果提供实验和仿真的C_(6)F_(12)O红外光谱信息,为C_(6)F_(12)O型气体绝缘设备提供FTIR检测技术,为C_(6)F_(12)O混合气体绝缘设备的混合比和微量体积分数检测提供了重要的理论支撑。

GLOBAL WELLPOSEDNESS OF MAGNETOHYDRODYNAMICS SYSTEM WITH TEMPERATURE-DEPENDENT VISCOSITY

The initial boundary value problem of the one-dimensional magneto-hydrodynamics system, when the viscosity, thermal conductivity, and magnetic diffusion coefficients are general smooth functions of temperature, is considered in this article. A unique global classical solution is shown to exist uniquely and converge to the constant state as the time tends to infinity under certain assumptions on the initial data and the adiabatic exponent γ. The initial data can be large if γ is sufficiently close to 1.

利用ATR-FTIR研究脂质纳米粒的鼻黏液渗透性

鼻黏液是影响疫苗和药物经鼻吸收的首要屏障。由于干扰因素复杂多变,在体评价黏液渗透性较难实施,多采用体外评价。现有的药物鼻黏液渗透性检测方法如细胞模型法、多粒子示踪技术等,存在细胞培养周期长、操作繁琐、成本高、可获得信息少且需要进行荧光标记等不足,对鼻黏膜制剂的体外评价具有很大的局限性,因此迫切需要建立一种快速、简便、灵敏的鼻黏膜制剂黏液渗透性评价方法。基于衰减全反射-傅里叶红外光谱(ATR-FTIR)对药物结构以及粘蛋白二级结构变化的敏感性,利用其对不同性质(粒径与电荷)脂质体的鼻黏液渗透性进行研究,通过FTIR图谱分析不同脂质纳米粒与黏液中粘蛋白的相互作用,建立了鼻黏膜制剂黏液渗透性的体外评价方法。方法学研究表明,对于聚乙二醇10000(PEG10000)、壳聚糖、海藻酸钠脂质体,该方法线性关系分别为Y=2.3866X+2.154、Y=1.8703X+0.2789、Y=1.13014X+0.0609,线性相关系数分别为0.9958、0.9945、0.9909,精密度RSD值分别为0.62%、0.73%、0.95%;重复性试验中RSD值分别为0.83%、0.97%、0.88%,说明该方法线性关系良好、精密度高、重复性好,可用于体外评价药物制剂在黏液中的渗透性。研究结果表明,利用ATR-FTIR在不同时间内扫描样品可得到不同脂质体制剂样品的强度增加的吸收带。对于不同粒径PEG脂质体而言,粒径越小其黏液渗透性越强;对于不同电荷脂质体而言,壳聚糖脂质体黏液渗透性最弱,海藻酸钠次之,PEG脂质体黏液渗透性最强。进一步研究表明,不同电荷脂质体黏液渗透性的差异源于其与粘蛋白相互作用,该结论可通过分析粘蛋白酰胺Ⅰ带所包含的各二级结构信息得到。综上,基于ATR-FTIR所建立的体外评价方法灵敏简便,可作为多种不同制剂的鼻黏液渗透性的快速测定,经改进后还可用于药物制剂在其他黏液中的渗透性评价,应用前景广阔。

Synthesis and helical twisting property of polymerizable chiral dopant with temperature-dependent solubility in liquid crystal

In this study, right-handed dicinnamate isosorbide was synthesized via the esterification reaction betweefi optically active isosorbide and cinnamate. The chiral dopant was characterized by FT-IR, ^1H NMR, elemental analysis, SEM, UV absorption spectrum. After dissolving in a nematic liquid crystal mixture, the chiral dopant exhibited a temperature-dependent solubility in the chiral nematic liquid crystal mixture. Meanwhile, a relatively high value of helical twisting power of the polymerizable chiral dopant was determined. The results show that the chiral dopant has great potential in achieving a polymer stabilized chiral nematic liquid crystal film with a broad-band selective reflection. C 2009 Huai Yang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

过饱和硼酸镁溶液结晶过程的原位FTIR研究

基于自制的湿度连续可调装置,结合衰减全反射傅里叶变换红外光谱(ATR-FTIR)技术,深入探究了镁硼酸盐体系的动态行为,包括章氏硼镁石、三方硼镁石和多水硼镁石三种硼镁石过饱和溶液的相转变与结晶过程。实现了样品池内环境相对湿度的连续调节,在蒸发过程中能够连续监测到镁硼酸盐过饱和溶液的动态化学行为,基底表面所制备的过饱和溶液液膜逐渐蒸发水分浓缩为超浓态,最终形成包含多种镁硼酸盐晶体的多相混合物。对基底表面镁硼酸盐过饱和溶液及相转化、结晶得到的镁硼酸盐晶体的红外光谱的连续测量,结合基于密度泛函理论计算的多种镁硼酸盐晶体的红外振动模式,阐明三种镁硼酸盐过饱和溶液中多聚硼酸根的存在形式、相变过程中多聚硼酸根离子的分布变化及最终结晶形成的镁硼酸盐晶体种类,总结了三种镁硼酸盐体系的硼酸盐物种分布变化的区别,给出相转变结晶全过程的反应机理并对比“稀释成盐”现象进行解释。研究结果:(1)在三种硼镁石过饱和溶液中,主要存在的多硼酸根离子是B_(3)O_(3)(OH)^(2-)_(5)。三种硼镁石过饱和溶液随着蒸发结晶后晶体中均可观察到章氏硼镁石[B_(4)O_(5)(OH)^(2-)_(4)],这是B_(3)O_(3)(OH)^(2-)_(5)发生聚合反应形成的稳定物种;(2)镁硼酸盐晶体中的三配位硼氧键非对称伸缩振动νas(B(3)-O)主要表现为向内伸缩,而溶液中的硼酸根离子主要表现为向外伸缩,这一振动方向的差异可以作为区分晶体和溶液中硼酸根离子存在的依据;(3)“稀释成盐”得到的镁硼酸盐中不存在B_(5)O_(6)(OH)^(-)_(4),本研究中B_(5)O_(6)(OH)^(-)_(4)仅在章氏硼镁石过饱和溶液相转变结晶过程中出现,解释为章氏硼镁石过饱和溶液中B_(4)O_(5)(OH)^(2-)_(4)更易发生聚合反应生成B_(5)O_(6)(OH)^(-)_(4)。研究拓展了硼酸盐体系研究的传统浓度范围,详细刻画了镁硼酸盐的动态演化过程,为相变过程中镁硼酸盐体系的红外光谱研究提供了全新的认识。