The competition of neutrino energy loss due to the pair,photo-,plasma process at the late stages of stellar evolution

Based on the Weinberg-Salam theory,the competition of the Neutrino Energy Loss (NEL) rates due to the pair,photo- and plasma process are canvassed.The ratio factor C1,C2 and C3 which correspond the different contributions of the pair,photo- and plasma neutrino process to those of the total NEL rates are accurately taken into account.The ratio factors are very sensitive to the temperature and density.The ratio factor C2 always is lower than the ratio factor C1 and C3.The pair NEL process is the dominant contribution before the crossed point O(C1=C3=0.45) and the plasma NEL process will be the main dominant contribution after the crossed point O.With increasing temperature,the crossed point O will move to the direction of higher density.     

Gaussian modification of neutrino energy loss on strongly screening nuclides 55Co and 56Ni by electron capture in stellar interior

Gaussian modifications of the neutrino energy loss (NEL) by electron capture on the strongly screening nuclides 55Co and 56Ni are investigated. The results show that in strong electron screening (SES),the NEL rates decrease without modifying the Gamow-Teller (G-T) resonance transition. For instance, the NEL rates of 55Co and 56Ni decrease more than two and three orders of magnitude for ρ7 = 5.86, T9≤ 5,Ye = 0.47, △ = 6.3, respectively. In contrast, due to Gaussian modification, the NEL rates increase about two orders of magnitude in SES. Due to SES, the maximum values of the C-factor (in %) on NEL of 55Co, 56Ni are of the order of 99.80%, 99.56% at ρ7 = 5.86 Ye = 0.47 and 99.60%, 99.65% at ρ7 = 106 Ye = 0.43, respectively.     

Influence of Temperature on the Luminescence Properties of MgAl2O4:Dy3+ Ceramics Synthesized by Spark Plasma Sintering

Physics of the Solid State - Transparent MgAl2O4:Dy3+ ceramic samples were synthesized by spark plasma sintering. Their optical properties, photo- and cathodoluminescence, the luminescence decay...     

H2， He混合稀释生长微晶硅锗薄膜

采用H₂,He混合气体稀释等离子辅助反应热化学气相沉积法生长微晶硅锗薄膜,并在生长过程中对等离子体进行光发射光谱在线监测.结果表明：混合气体稀释法可以有效提高等离子体中的原子氢数目,降低等离子体中的电子温度;用XRD和光暗电导率表征样品的微结构和光电特性时发现,通过优化混合稀释气体中He和H₂气体的比例,能够减少薄膜中的缺陷态,促进薄膜<220>择优取向生长,有效改善微晶硅锗薄膜结构,提高光电吸收性能. 关键词： 化学气相沉积 微晶硅锗薄膜 光发射光谱 X射线衍射     

Numerical and experimental investigations of splat geometric characteristics during oblique impact of plasma spraying

Splats are obtained on the substrates inclined at different angles (0°, 20°, 40° and 60°) by plasma spraying process and characterized by SEM and WYKO^® optical surface profiler. Numerical model is developed using CFD software FLOW-3D^® to simulate the process of droplet impact, spreading and solidification onto the substrates. Splat characteristics such as spread factor, aspect ratio and fractional factor are defined and compared between simulation and experiment. Fair agreements are obtained. In addition, the impacting behavior including spreading and solidification are analyzed in details from the simulation results. The rates of reduction in droplet kinetic energy during impact, spreading and solidification are also compared between different inclination angles.     

pp的超子对湮灭与SU(3)对称性

本文用极点近似和有破坏的SU(3)对称结合起来处理了pp的超子对湮灭,得到了与实验符合的角分布与分支比。对称性破坏表现在:(1)质量差,(2)在顶点引进一个反比于介子质量的因子。     

显微激光拉曼定量分析CO_2气体碳同位素组成方法研究

制备了一系列不同比例的~(12)CO_2/N_2和~(13)CO_2/N_2混合物,对样品进行显微激光拉曼测试分析后发现气体拉曼特征峰峰面积比与其摩尔分数比成正比例关系,拟合方程的斜率被认为是拉曼量化因子F_(12CO_2)和F_(13CO_2)。用气相组分中只含有~(12)CO_2和N_2的流体包裹体验证了当F_(12CO_2),为1.163 49时,根据气体的拉曼特征峰峰面积比能估算出其摩尔分数比。由线性拟合后的方程斜率得出F_(13CO_2)和F_(12CO_2)分别为1.610 86和1.163 49,它们的比率F_(13CO_2)/F_(12CO_2)是1.3845。在确定稳定同位素分子的拉曼参数和实验条件基础上,CO_2气体碳同位素摩尔分数比C_(12)/C_(13)可根据A_(12Co_2)/A_(13CO_2)(拉曼峰峰面积比)和F_(13CO_2)/F_(12CO_2)的乘积求出。此外,用已知摩尔分数比(C_(12)/C_(13))的人造包裹体验证了此方法具有一定的可行性,可以建立起定量分析CO_2气体碳同位素激光拉曼测试方法。     

一种基于单负Metamaterials成对结构的带通滤波器的设计

提出了一种基于单负Metamaterials对的带通滤波器的设计原理,给出了这种带通滤波器的谐振频率的表达式,对其谐振频率及带宽与其决定因素之间的关系进行了计算,对计算结果进行了讨论,为设计单负Metamaterial对带通滤波器的理论与方法提供了依据。研究结果表明：利用单负Metamaterials对的确可以实现带通滤波器;ENG板的磁导率μ1、MNG板的介电常数ε2、电等离子体频率ωep、磁等离子体频率ωmp、两个层的厚度比值a这五个因素决定了这种滤波器的中心频率;两个层的厚度及二者之间的比值决定这种滤波器的带宽。     

Molecular dynamics simulation studies of cryoprotective agent solutions: the relation between melting temperature and the ratio of hydrogen bonding acceptor to donor number

Molecular dynamics simulations have been carried out for glycerol–water–sodium chloride ternary solution due to its important role in cryopreservation engineering. The radial distribution functions for atom pairs potentially related to C–H ··· O and O–H ··· O hydrogen bonds were calculated. The radial distribution functions for the H (connected to C)–O atom pair do not exhibit peaks between 2 and 3 Å, whereas the radial distribution functions for the C–O atom pair exhibit distinct peaks between 3 and 4 Å. The reason for this is because most C–H ··· O geometries are bent and deviate from linearity. The ratios of acceptor to donor numbers for water and glycerol molecules decrease as the solute concentration increases. A characteristic concentration has been found that divides solutions with different mechanisms. Below the characteristic concentration, the melting temperature is linearly related to the ratio of acceptor to donor number for water molecules, whereas above the characteristic concentration, the melting temperature is linearly related to the ratio of acceptor to donor number for glycerol molecules. Further studies indicate that the relations are independent of hydrogen bonding criteria and temperature.     

Effect of SiO2 nanoparticles sizes on the optical properties and radiation resistance of powder mixtures ZrO2 with micron sizes

One way to improve photo- and radiation resistance of materials is by the modification of their nanoparticles. The purpose of work is to study the optical properties and radiation resistance of ZrO₂ powder mixtures with SiO₂ nanoparticles without high-temperature heating. The ZrO₂ powders with micron sizes were mixed in a ratio of 100:7 mas.% with SiO₂ nanopowders. The nanopowders were obtained by combustion of silicon tetrachloride in air plasma. Samples were characterized using X-ray diffraction (XRD), high resolution scanning electron microscopy (SEM), and a simulator of the environment of outer space “Spectrum”. The radiation resistance increase of zirconia dioxide powders with micron-sized grains by the addition of silica nanoparticles without heating at a high temperature was found. For these purposes only water evaporation at 150 °C was used. The effectiveness of the modification reaches values of 2.1 times. This value is close to or even more in comparison to its values in the modification by using high-temperature heating. This result is significant for the practical use of this method of incensement of the radiation resistance of oxide reflecting powders.     

Frequency dependence of EPR signal intensity, 250 MHz to 9.1 GHz

Experimental EPR signal intensities at 250 MHz, 1.5 GHz, and 9.1 GHz agree within experimental error with predictions from first principles. When both the resonator size and the sample size are scaled with the inverse of RF/microwave frequency, omega, the EPR signal at constant B(1) scales as omega(-1/4). Comparisons were made for three different samples in two pairs of loop gap resonators. Each pair was geometrically scaled by a factor of 6. One pair of resonators was scaled from 250 MHz to 1.5 GHz, and the other pair was scaled from 1.5 GHz to 9 GHz. All terms in the comparison were measured directly, and their uncertainties estimated. The theory predicts that the signal at the lower frequency will be larger than the signal at the higher frequency by the ratio 1.57. For 250 MHz to 1.5 GHz, the experimental ratio was 1.52 and for the 1.5-GHz to 9-GHz comparison the ratio was 1.14.     

Electron and positron nonthermality effects on the formation of damped solitons in collisional multi-component plasmas

Electrostatic damped field characteristics in non-thermal fast positron and electron plasma having fluids of positive and negative pair ions have been discussed when collisional frequencies parameters are taken into account. The damped and forced form of Kadomtsev-Petviashvili (DKP) equations have been obtained. The plasma parameters effects of electron density ratio, the negative ionic density ratio, the pair ionic charge ratio, the density of positron ratio, the collisional frequencies, ion mass ratio and the fast non-thermality on the electrostatic damped and forced field formations, as observed in D-F -ionosphere and laboratory experiments have been investigated.     

螺双杯[4]芳烃-冠-3醚在溶液中构象的研究

研究了螺双杯[4]芳烃-冠-3醚在溶液状态下的¹H、¹³C、¹H-¹³C HMQC、¹H-¹³C HMBC、¹H-¹H TOCSY等核磁共振谱,对其¹H、¹³C谱进行了归属,确定了室温该化合物在溶液状态下的稳定构象为锥式,并利用2D NOESY近似求出杯芳烃区的各种氢的距离,以此为约束进行了模拟淬火计算,证实了2D NOESY谱中多种羟基存在方式,并利用二维交换矩阵计算得出几种羟基的交换速率及其与溶剂中痕量水的交换速率.     

纳秒激光电离分子团簇产生高离化离子的激光波长效应

 利用脉冲分子束-激光电离-飞行时间质谱仪，在10⁹～10¹² W·cm^-2激光功率密度条件下，考察了Nd：YAG激光器输出的1 064，532，266 nm波长的激光与苯、氨、硫化氢等团簇的相互作用。发现1 064 nm的激光可以电离分子束产生高离化态的C⁴⁺，N⁵⁺，S⁶⁺等离子；波长为532 nm的激光则电离产生价态较低的C³⁺，C²⁺，N³⁺，N²⁺， S⁴⁺，S³⁺以及S²⁺ 等离子；在266 nm波长条件下进行实验，没有产生任何高价离子。提出了一个“多光子电离引发-逆轫致吸收加热-电子碰撞电离”模型来解释高价离子的产生。激光场下电子在团簇内部的逆轫致加热是整个过程的关键步骤，电子被加热的速度正比于激光波长的平方。这可以解释为何长波长的激光有利于更高价态离子的产生。     

氮化碳薄膜的X射线光电子谱

用ＸＰＳ研究射频－直流等离子体增强化学气相沉积获得的氮化碳薄膜的化学结构。Ｃ１ｓ和Ｎ１ｓ芯能级电子谱分析表明：在ＣＮ膜中含有Ｎ－ｓｐ＾３和Ｎ－ｓｐ６２两类化学结构,在高含Ｎ膜中还含有少量的Ｎ－ｓｐ相,且代表Ｎ－ｓｐ＾３结构的原子 比为１．２８,接近４：３,证明此膜中存在类β－Ｃ３Ｎ４相。     

基于电化学与热能的耦合关系演算聚合物锂离子动力电池的温度状态及分布

基于电化学-热耦合模型研究聚合物锂离子动力电池放电过程热行为, 分析了放电倍率、冷却条件对电池放电过程的温度变化及分布的影响规律. 结果表明: 3C放电时, 模型计算结果与实测结果的平均偏差为0.57 K, 方差为0.15, 说明模型准确度较高. 电芯的平均生热率在整个放电过程中呈现出增加的趋势, 初期和末期增长较快. 大倍率放电时, 与电流密度的平方呈正比的不可逆热所占的比重较大, 小倍率放电时, 电化学反应可逆热占主导. 改善冷却条件能降低电池放电过程的平均温度, 对流传热过程的表面传热系数为5 W/(m²·K), 1 C, 3 C, 5 C放电结束时, 电芯的平均温升为分别为6.46 K, 17.67 K, 27.53 K, 当对流传热过程的表面传热系数增加至25 W/(m²·K)时, 温升比自然对流条件下相同倍率放电时的温度分别降低了2.91 K, 4.68 K, 5.62 K, 但电芯温度分布的不一致性也会加剧. 关键词： 电化学 耦合 锂离子动力电池 温度分布     

BaFCl_xBr_（1－x）：Sm的发光研究

本文报道了ＢａＦＣｌｘＢｒ１－ｘ：Ｓｍ中Ｓｍ２＋、Ｓｍ３＋的光致发光、光激励发光和热释发光特征．讨论了基质组分对发光的影响及Ｓｍ２＋、Ｓｍ３＋的相对发光效率．发现Ｓｍ２＋的复合发光能力大于Ｓｍ３＋的复合发光能力，并从复合发光的过程及途径对这一现象进行了说明．     

BaFClxBr1-x：Sm的发光研究

本文报道了BaFClxBr1-x:Sm中Sm2+、Sm3+的光致发光、光激励发光和热释发光特征.讨论了基质组分对发光的影响及Sm2+、Sm3+的相对发光效率.发现Sm2+的复合发光能力大于Sm3+的复合发光能力,并从复合发光的过程及途径对这一现象进行了说明.     

Modification of the spectra of correlated charm-anticharm quark pairs in the quark-gluon plasma

Heavy quarks play an important role in probing the properties of strongly interacting quark-gluon plasma(QGP)created in ultra-relativistic heavy-ion collisions.We study the interactions of single heavy(charm)quarks and correlated charm and anticharm(ccˉ)quark pairs with the medium constituents of QGP by performing fireball+Langevin simulations of the pertinent Brownian motion with elastic collisions.Besides studying the traditional observables,the nuclear modification factor and the elliptic flow of single heavy quarks in QGP for different thermal relaxation rates,we also study the broadening of the azimuthal correlations of charm and anticharm quark pairs in the QGP medium for different relaxation rates and transverse momenta classes.We quantified the smearing of ccˉpair azimuthal correlations with an increasing thermal relaxation rate:while the(nearly)back-to-back correlations among ccˉpairs are almost completely washed out at low transverse momentum(pT),these correlations at high pT largely survive the pair diffusion.This provides a novel observable for diagnosing the properties of QGP.     

Photo- and thermal-diffusions of metals into As2S3 glass

Photo- and thermal-diffusion effects of Ag and Cu into As₂S₃ bulk glass have been studied. It has been clarified that the photo-diffusion process is attributed to a purely optical effect. Some differences in diffusing process between Ag and Cu have been clearly shown both for the photo- and thermal-diffusions.