Hyperon Dynamics in Heavy-Ion Collisions near Threshold Energy

Within the framework of quantum molecular dynamics transport model,the isospin and in-medium effects on the hyperon production in the reaction of ~(197)Au+~(197)Au are investigated thoroughly.A repulsive hyperon-nucleon potential from the chiral effective field theory is implemented into the model,which is related to the hyperon momentum and baryon density.The correction on threshold energy of the elementary hyperon cross section is taken into account.It is found that the Σ yields are suppressed in the domain of midrapidity and kinetic energy spectra with the potential.The hyperons are emitted in the reaction plane because of the strangeness exchange reaction and reabsorption process in the nuclear medium.The Σ~-/Σ~+ ratio depends on the stiffness of nuclear symmetry energy,in particular in the high-energy region(above 500 MeV).     

N-乙基吡咯S1态超快动力学：飞秒时间分辨光电子成像研究

N-乙基吡咯是吡咯分子的一个乙基取代衍生物,它的激发态衰变动力学目前为止很少被研究. 本文利用飞秒时间分辨光电子成像的实验方法研究N-乙基吡咯分子S₁态的衰变动力学. 实验采用241.9和237.7 nm的泵浦激发波长. 在241.9 nm激发下,得到5.0±0.7 ps,66.4±15.6 ps和1.3±0.1 ns三个寿命常数. 在237.7 nm激发下,得到2.1±0.1 ps和13.1±1.2 ps两个寿命常数. 所有寿命常数都归属为S₁态的振动态. 本文并对不同S₁振动态的弛豫机理进行了讨论.     

Charged torus-like black holes as heat engines

We investigate the thermodynamical properties of charged torus-like black holes and take it as the working substance to study the heat engines. In the extended phase space, by interpreting the cosmological constant as the thermodynamic pressure, we derive the thermodynamical quantities by the first law of black hole thermodynamics and obtain the equation of state. Then, we calculate the efficiency of the heat engine in the Carnot cycle as well as the rectangular cycle,and investigate how the efficiency changes with respect to volume. In addition, to avoid a negative temperature, we emphasize that the charge of this black hole cannot be arbitrary. Last,we check the calculation accuracy of a benchmark scheme and discuss the upper bound and lower bound for charged torus-like black hole in the scheme.     

Joule–Thomson expansion of RN-AdS black hole immersed in perfect fluid dark matter

In this paper, we study the Joule–Thomson expansion for RN-Ad S black holes immersed in perfect fluid dark matter. As perfect fluid dark matter is one of the dark matter candidates, we are interested in how it influences the thermodynamic properties of black holes. Firstly, the negative cosmological constant could be interpreted as thermodynamic pressure and its conjugate quantity as the thermodynamic volume, which give us more physical insights into the black hole. Moreover, we derive the thermodynamic definitions and study the critical behaviour of the black hole. Secondly,the explicit expression of Joule–Thomson coefficient is obtained from the basic formulas of the pressure, the volume, the entropy and the temperature. Then, we obtain the inversion curves in terms of charge Q and parameter λ. Furthermore, we analyse the isenthalpic curve in T–P graph with the cooling–heating region determined by the inversion curve. At last, we derive the ratio of minimum inversion temperature to critical temperature and compare the result with that in the RN-Ad S case.     

New approach for amplitudes with multiple fermion lines

A new approach for tree-level amplitudes with multiple fermion lines is presented. It primarily focuses on the simplification of fermion lines. By calculating two vectors recursively without any matrix multiplications, the result of a fermion line is reduced to a very compact form depending only on the two vectors. Comparisons with other packages are presented, and the results show that our package FDC provides a very good performance in the processes of multiple fermion lines with this new approach and some other improvements. A further comparison with WHIZARD shows that this new approach has a competitive efficiency in computing pure amplitude squares without phase space integration.     

基于高光谱技术的蛋白粉掺假检测研究

蛋白粉是健身者必备的营养补剂,市场需求在不断增加,一些不法商家为了谋取利益,在蛋白粉中加入廉价的粉末售卖。传统的蛋白粉掺杂的检测方法费时、费力,操作复杂,且成本昂贵。高光谱技术具有易于操作、在不损害实验样本的情况下可快速检测等优点,因此,提出使用高光谱技术以实现蛋白粉掺假检测。在蛋白粉中分别加入质量百分数5%～60%,浓度间隔5%的三类掺假物（玉米粉、大米粉和小麦粉）,并采集所有样本的光谱信息。在对蛋白粉中的玉米粉、大米粉和小麦粉三类掺假物进行定性判别时,首先分别采用卷积平滑（SG）、标准化（Normalize）、多元散射校正法（MSC）、基线校正（Baseline）和标准正态变换（SNV）的预处理方法对光谱数据进行处理,然后建立基于主成分回归（PCR）、反向传播神经网络（BPNN）和随机森林（RF）的模型,其中基于全波段光谱MSC预处理方法下建立的RF模型最优,其整体准确率达到了100%,其对应的R_P和RMSEP分别为0.997 9和0.018 9。在对蛋白粉中不同掺假物浓度进行定量分析时,对三类掺假样本的光谱分别进行SG,Normalize,MSC,Baseline和SNV的预处理,并建立LSSVM模型;比较不同预处理方法下的各模型之间的性能,在蛋白粉中掺玉米粉、大米粉和小麦粉的LSSVM预测模型最佳预处理方法分别是无、Baseline和Normalize,然后,采用连续投影算法（SPA）和竞争性自适应重加权算法（CARS）对其筛选,并建立LSSVM模型,三类掺假样本的SPA-LSSVM模型对应的R_P为0.989 0,0.986 0和0.997 9,CARS-LSSVM模型对应的R_P为0.991 0,0.994 6和0.999 1,故三类掺假样本的CARS-LSSVM模型预测效果更佳。研究表明：高光谱技术可以实现对蛋白粉掺假的定性、定量的检测,并且操作简单、检测快速和无损。     

冷原子荧光光谱中数字基线估计方法的研究

水体中汞的存在形态有单质汞、无机汞和有机汞三种。其中,甲基汞是主要的有机汞形态,毒性远高于单质汞和无机汞。测量水体中的甲基汞的方法有很多,冷原子荧光光谱法是测量水体中甲基汞的推荐方法。冷原子荧光光谱法是原子发射光谱法和原子吸收光谱法综合发展而来的元素分析方法。经过多年的发展与完善,是元素分析最常用的分析技术之一,具有灵敏度高、检出限低等特点,被广泛应用于环境科学、生命科学、地质等领域。由于检测仪器的背景噪声和色谱柱分离效果的影响,冷原子荧光光谱出现基线漂移和信号拖尾等干扰因素,严重影响冷原子荧光光谱数据的峰面积计算和痕量甲基汞的定量分析。其中,基线漂移是最主要干扰因素。目前,改进模拟器件参数和数字基线估计是解决基线漂移的的两种重要手段。在改进模拟器件参数方面,有激发光源使用空心阴极汞灯、闭环控制的热阴极低压汞灯等,但存在实验设备复杂、成本高昂等缺陷;在数字基线估计方面,有最小二乘法、差值拟合法等,但存在基线估计不稳,含量计算不准等缺点。基于此,提出了一种基于小波变换的数字基线估计方法。首先,分析甲基汞的冷原子荧光光谱微观信号和基线漂移现象,建立冷原子荧光光谱信号和基线漂移数理模型;其次,根据冷原子荧光光谱信号模型的特点,以小波变换为研究基础,研究合适的母小波模型,将母小波模型与基线漂移模型进行卷积,卷积结果恒为零,理论上证明了基线漂移现象经过小波变换后会被消除;再次,以100 pg标样甲基汞为例,实验验证了小波变换能够有效地消除基线漂移的干扰和信号拖尾的影响;最后,在仪器相对标准差（RSD）为1.29%~3.40%的条件下,对0,10,20,50,100,500以及1 000 pg的标样甲基汞溶液进行5次重复实验,分别建立小波变换前后峰面积平均值校准曲线,校准曲线的相关系数（R2）由小波变换前的0.994提高到小波变换后的0.997。实验结果表明,该方法能够有效地消除测量仪器基线漂移和信号拖尾的影响,提升了系统测量准确性。     

热击处理对离体子叶培养物花芽分化与可溶性蛋白谱的影响

黄瓜幼苗胚轴的不同部位对离子体子叶培养物器官分化的影响是不同的,热击处理具不同长度胚轴的黄瓜幼苗,其子叶培养物的直接花芽分化率不同,其中以单去根处理的为最高,去根＋去／2胚轴的为最低,对照和去根＋去3／4胚轴的居中,结果提示胚轴中存在着与成花有关的促进和／或抑制因子,热击无根苗产生了分子量约为67－94kD的热激蛋白,热击处理还使中性区域蛋白质含量下降。     

NaF饮水喂养的小白鼠肝脏线粒体代谢热化学研究

利用 L KB2 2 77生物活性检测系统 ,测定了用含不同浓度 Na F饮水喂养的小白鼠肝脏线粒体代谢热曲线 ,实验表明 ,饮水中 Na F浓度增加 ,最大热功率增大 ,代谢产热增加 ,停滞期和活性维持时间缩短 .热曲线测定完毕后的样品 ATP浓度分析表明 ,随着 Na F浓度增加 ,系统的 ATP浓度降低 .结合透射电镜对肝细胞超微结构研究结果 ,根据化学渗透假说对实验结果进行了比较完满的解释     

新疆农业生产要素转移问题初探

本文通过对新疆农业生产函数的分析。讨论了生产要素转移情况。得出:1 新疆的土地资源已经过度使用;2 劳动力资源潜力很大,其转移方向正从流向第三产业转向第二产业;3 新疆农业资金缺乏,部分农业资金被非农业侵占。