Stability of Nuclei Based on the New Proton and Neutron Model

According to the new proton and neutron nuclear picture described earlier, the structure of the nucleus will also be given a new interpretation. The role of the delocalized electrons detached from the outer shell of neutrons is shown in the binding energy value of the nucleus. It is pointed out that the spatial arrangement of nucleons is also very important for the stability of nuclei according to the analyzation of the magic numbers from a geometric point of view.

Linear stability analysis on a spherical particle growing from a binary melt under the far-field flow

The solutions of temperature and solute fields around a spherical crystal growing from a binary melt under the far-field flow are obtained.Based on the results,a linear stability analysis on the spherical interface growing from the binary melt under the far-field flow is performed.It is found that the constitutional supercooling effect ahead of the spherical crystal interface under the far-field flow is enhanced compared with that without the flow.The growth rate of the perturbation amplitude at the up-wind side of the spherical crystal interface is larger than that at the down-wind side.The critical stability radius of the crystal interface decreases with the increasing far-field flow velocity.Under the far-field flow,the whole spherical interface becomes more unstable compared with that without the flow.

Effects of 5%Ni addition on thermal stability and crystallization behavior of Mg_(65)Cu_(25)Tb_(10) bulk metallic glass

The effects of 5%Ni addition on the glass forming ability,thermal stability and crystallization behavior of Mg65Cu25Tb10 bulk metallic glass were investigated using X-ray diffractometry,differential scanning calorimetry and transmission electron microscopy.The small amount of Ni addition reduces the glass forming ability and thermal stability due to a significant decrease in the crystallization activation energy.Analyses of crystallization kinetics give evidence to the existence of quenched-in nuclei in amorphous Mg65Cu20Ni5Tb10.Final crystallization products are basically same for Mg65Cu25Tb10 and Mg65Cu20Ni5Tb10.

Cyclic feeding regime may delay aging in animals by enhancing the hepatocytes nuclei structure

Background:The liver is fundamental for keeping up the entire body’s homeostasis.The liver hepatocytes have been shown to undergo genomic instability with aging.The stability of the hepatocytes depends on its nuclear architecture.Calorie restriction has been shown to extend life-span favorably and this may be through the reorganization of the nuclear structure.Objective:To study the effect of cyclic feeding regime on the chromatin assembly anchored to the nuclear membrane scaffold of rat models hepatocytes nuclei.Method:Rats models underwent cyclic feeding regime,after which nuclei were isolated;then,we investigated the chromatin decondensation and nuclear membrane disintegration of the hepatocytes using fluorescence imaging methods.Results:In 60 seconds,protease decondensed the chromatin and disintegrated the nuclear membrane structure of controls.After the first fasting,the time increased to 145 seconds in 3-month-old rats.The first refeeding increased the time to 156 seconds with a further rise to 340 seconds following the second fasting,then dropped to 116 seconds by the second refeeding.20 months old rats showed 186 seconds increase in the time of chromatin decondensation and nuclear membrane disintegration after the first fasting,with a decrease to 140 seconds observed after first refeeding.The second fasting increased the time to 165 seconds,which then slightly decreased to 163 seconds after the second refeeding.Conclusion:These results show that intermittent fasting may have acted on chromatin histone interactions and the structural lamin networks of the nuclear membranes in bringing about nuclear stability,which is essential for normal cellular function.

HIRFL and studies of hot nuclei and nuclei far from stability

HEAVY ion physics has been rapidly developing at the limits of energy (nuclear temperature), isospin and spin. Heavy ion research facility of Lanzhou (HIRFL) is of cyclotron family delivering intermediate energy heavy ions. During the recent years, progress has been made in the studies of heavy ion physics as well as in the development of the HIRFL. This review article will

A Study on the Far Wake of Elliptic Cylinders

The evolution of far wake of stationary elliptic cylinders with angle of attack is investigated for the unsteady flow at Re=200 using a stabilized finite-element method.The Reynolds number,Re,is based on the major axis of cylinder and free-stream speed.Cylinder aspect ratios,AR considered are 0.2,0.5 and 0.8 while the angle of attack,αvaries from 0° to 90°.With increasingα,the Karman or primary shedding frequency of each cylinder decreases monotonically while the primary wavelength and time-averaged as well as r.m.s.drag increase monotonically.The time-averaged lift and moment coefficients initially increase withαand then decrease.The power spectrum analysis of unsteady transverse velocity signal at various stations along the wake centerline is used to study the associated frequencies.The Karman or primary shedding frequency exists for eachα.For the AR=0.2 cylinder,the secondary and subsequently,low magnitude tertiary frequencies appear in the wake asαcontinues to increase from 30°.In contrast to the decaying nature of primary frequency withα,secondary frequency exhibits a nonmonotonic variation.The secondary frequency in general is not a sub-harmonic of the primary.This suggests that the secondary structures do not form due to merging of primary vortices.With increasingα,the location of formation of secondary structures advances upstream.For a given orientation,the upstream advancement is more dominant with decreasing AR.Power spectrum analysis indicates that the wake state for confined flow is characterized by the primary frequency alone,i.e.the imposition of blockage suppresses the formation of secondary structures.

Radioactivity of nuclei in a centrifugal force field

Radioactivity of nuclei in a centrifugal force field of an ultracentrifuge is considered for heavy radioactive nuclei, i.e., for the same nuclei, but with a significant virtual mass thousands of times larger than the actual mass and is characterized by an angular momentum. As the nucleus leaves the centrifugal force field, the virtual mass disappears, but the spin number appears and/or changes. The role of centrifugal and gravitational forces in radioactive decay of nuclei is studied. According to the terminology of western researchers, such a virtual mass state is called the dynamic gravitation which is more adequate. The oscillator and possible changes in the nucleus state are considered under conditions of dynamic gravitation and taking into account features of atomic nucleus physics. To a first approximation, the drop model of the nucleus was used, in which shape fluctuations have much in common with geophysical and astrophysical analogues. Shape fluctuations of analogues strongly depend on the gravitational force g defined by their mass (or nucleus mass). Experiments were performed by radiometric measurements of transbaikalian uranium ore (1.5 g) with known composition in a centrifuge at various rotation rates or gravitational forces g. The existence of characteristic times or the effect of rotation frequencies (i.e., g) on atomic nuclei, which, along with the nucleus type itself, controls the nucleus response to perturbation (stability increase or decay), is found statistically significant.

激光远场大气稳定传输的光场调控技术研究

大部分激光器产生的激光为相干光束,在理想环境下,激光到达远场后其相干特性与出射时保持一致,且光强分布均匀,但由于大气环境中湍流的存在,激光到达远场后发生相互干涉,产生振幅起伏,即光强闪烁现象。文中主要从多个角度分析该现象形成的原因,并主要从相位、偏振态两个方面出发,提出相应的解决措施,并完成验证实验。实验结果表明,所提出的解决措施可实现较好的分布效果;又从理论方面提出了光源光束整形措施,提升激光远场光斑分布的性能;最后结合实际应用,分析了高空相对于地面大气湍流的区别,以及激光传输角度对激光远场传输的影响。从实际应用方面,涵盖针对激光远场大气传输能量稳定性的多项解决方案,用于指导启发同领域内相关技术的攻关,具体问题可根据文中原理内容提出具体实现方式。

酸醚比对C-S-H/PCE/DL-AL晶核早强剂性能的影响

本文利用聚羧酸型分散剂(PCE)和铝酸脂偶联剂(DL-AL)制备水化硅酸钙(C-S-H)纳米晶核早强剂,并通过透射电子显微镜(TEM)和动态光散射(DLS)分析不同酸醚比对复合体系稳定性和早强剂产品性能的影响。结果表明:当PCE酸醚比为6:1并添加DL-AL时获得的C-S-H/PCE/DL-AL纳米晶核粒径最小,中值粒径为165nm,稳定性最好;水泥净浆初凝和终凝时间分别缩短169min和182min;C50管片混凝土8h和10h抗压强度分别提高至23MPa和30MPa。

Islands of stability and quasi-magic numbers for super- and ultra-heavy nuclei

In the framework of Strutinsky＇s approach, we calculated the shell and the residual pairing correction energies for 5569 even-even nuclei in the range 72 ≤ Z ≤ 282 and 96≤N ≤ 540. Quasi-magic numbers and deformed islands of stability that reside in a range defined by Green＇s formula and the two-neutrons drip line are introduced. We present 36 quasi-magic proton and 53 quasi-magic neutron magic numbers that contribute to the formation of 133 deformed islands of stability along the N-Z space. The quasi-magic proton and neutron magic numbers volatile as the mass number increases and other magic numbers take over. Consequently, the deformed islands of stability fail to exhibit a pattern along the search space covered.

远离稳定线核研究进展

近几年在对远离核的实验研究中,观测到了理论预言的新衰变模式,如45Fe的双质子衰变,β-缓发裂变;对中子滴线外一些核的存在可能性也进行了较多的实验探索和理论分析;开始了对人们一直关注的中子集团存在可能性的实验探索.远离核谱学和衰变性质研究逐渐深入,通过对一些远离核第一激发态能量的系统比较和许多远离核β衰变Q值的测量,以及核质量的精确测量,发现在远离核区,原有的一些幻数消失,代之产生了一些新的幻数,对其产生原因的理论分析做了简要的综述.

水合盐相变热长期贮存的研究

选用的水合盐经添加晶核抑制剂后,能长期保持过冷稳定性,其相变热至少可贮存三个月至一年以上,随时可提供56℃到40℃的热量,贮热量分别为230kJkg^(-1)和168kJkg^(-1),可作为中长期贮热之用。

远离β稳定线奇异核性质的理论研究

回顾了对远离β稳定线奇特核性质的理论研究现状，并用相对论平均场理论研究了远离β稳定线奇特核的性质．包括轻核的中子晕和质子晕。

远红外Ge-Ga-Te-Ag硫系玻璃性能研究（英文）

采用传统的熔融-淬冷法制备了一系列的（Ge15Ga10Te75）100-x（Ag）x硫系玻璃样品.通过X射线衍射、差式扫描量热法、傅里叶红外光谱仪等测试了玻璃样品的热学及光学性能.结果表明该玻璃具有良好的非晶态特性和热稳定性,玻璃开始析晶温度和玻璃转变温度的差值都超过了100℃.随着Ag含量的增加,玻璃的吸收截止边产生了红移.通过提纯,Ge-Ga-Te-Ag玻璃在1.8-20μm有着较宽且平坦的红外光学窗口.Ge-Ga-Te-Ag玻璃组分的优良性质使其在红外领域具有广阔的应用前景.

原型装置主放光路稳定性实验研究

为了研究高功率固体激光器光束指向的漂移情况,根据原型装置打靶误差预算中各部分的权重,分析了主放光路输出光束允许的角度漂移误差,即主放输出光束的角漂不超过10.6μrad。实验中选取了其中的一束,主放远场测量系统在37m in内共采集到了144发次的远场图像,在MATLAB编程中使用阈值法和重心法处理每帧远场图像,将光束的漂移量在x和y方向上分解,利用均方根的概率统计方法,计算得到了主放输出光束的角度漂移误差,x方向为3.47μrad,y方向为4.09μrad。实验结果表明,主放光路的稳定性达到了设计指标,能够满足打靶要求。

国家射击队男子手枪激光测试研究

男子手枪速射是特殊的射击项目,其动作技术相对其它射击项目精细而又复杂。激光测量技术恰恰能很好地解决手枪速射技术的检测与分析。利用激光测试技术对国家射击队手枪速射运动员的动作技术进行研究,为教练员训练提供技术支持,也为其他研究者提供参考。研究结果表明:1)国家射击队3名手枪速射运动员据枪质量高,8 s、6 s射击击发前能形成小稳定区,横向运枪平稳、规范,击发后枪的跳动规范,整体动作一致性好。2)射击节奏除LZS 8 s射击为匀加速节奏外,一般为匀速节奏。3)3名射手技术相比,LZS技术比较突出,规律性、节奏感强,动作更加规范一致。但与欧洲选手相比,还有提升的空间。4)针对偶尔出现远弹问题,建议加强对上臂和肩部肌肉的专项训练,提高据枪稳定性,提升控枪、运枪能力。

反转岛附近原子核奇特性质研究进展

反转岛附近原子核奇特性质的研究是当前核物理研究的热点。首先简要回顾和介绍了反转岛附近原子核奇特性质的实验进展,然后介绍了对这些奇特核性质的理论研究进展。主要包括相对论平均场模型、壳模型、Hartree-Fock模型和宏观-微观模型在该区域的发展和研究结果。重点介绍了宏观-微观模型在反转岛附近原子核奇特性质研究中的进展。此外,还分析和比较了各种理论模型在描述反转岛附近原子核性质上取得的成功和模型之间的差异。

羊毛/远红外中空涤纶混合保暖絮片的开发

采用针刺加工工艺开发了低比例羊毛/远红外中空涤纶混合保暖絮片,并对其性能进行了对比测试分析。结果表明低比例羊毛/远红外中空涤纶混合保暖絮片不仅保暖效果良好,而且还改善了纯羊毛保暖絮片的尺寸不稳定性,可达到絮片产品的服用性能要求。

超重新核素合成研究进展

随着重离子加速器和放射性核束装置的发展,人们对于核物理的研究不再仅仅局限于稳定核,更是将研究对象扩展到一些极限条件,比如探索原子核高温高密极限、自旋极限、同位旋极限,以及电荷和质量极限等.对于探索电荷和质量极限而言,如何合成长寿命超重核、是否存在“超重稳定岛”以及如何研究超重原子核的性质,成为当前核物理学研究的前沿领域.本文回顾了超重核的产生机制、定义和衰变模式,详细介绍了国内外关于超重核合成的现状和研究进展.其中包括理论上和实验上合成超重核素最新研究进展,重点针对重离子熔合反应和多核子转移反应研究情况展开讨论,并简介了国际上核科学大装置未来开展超重核研究的计划.同时,对北京师范大学参与93号超铀新核素^(223,224)Np的合成情况进行了评述,并针对近年来合成Z=119和120超重核素的最新研究进行了总结展望.

稀有事件搜索

简单介绍了远离核奇异性质研究的科学意义,报道了稀有事件的搜索方法,以高生成额、高分离效率和高探测效率的方法搜索稀有事件。通过放射化学分离方法从天然Th中提取出镭元素,准备薄的228Raβ→-228Ac源。由60MeV/u18O离子照射天然Th靶引起的232Th-2p反应产生230Ra,通过放射化学分离方法从被照射的靶中提取出镭元素并制成薄源,经230Raβ→-230Ac得到230Ac。利用35MeV的质子束轰击ThO2粉末靶,通过232Th(p,3n)反应产生230Pa核,经用放射化学分离方法分离出Pa,并制成230Paβ→-230U测量源。用固体径迹探测器和PHGe"射线探测器记录和测量来自源中的裂变碎片(重离子)和"谱,观测到它们的!延发裂变或重离子事件,得到228Ac和230Ac的!延发裂变概率分别为(5±2)×10-12和(1.19±0.85)×10-8,230U发射22Ne相当于α衰变的分支比B=$Ne/$#为(1.3±0.8)×10-14。