Breathing Effect in a Cobalt Phosphonate upon Dehydration/Rehydration: A Single‐Crystal‐to‐Single‐Crystal Study

Two cobalt phosphonates, [Co₂(2,2′‐bpy)₂(H₂O)(pbtcH)] ( 1 ) and [Co₂(H₂O)(pbtcH)(phen)₂] ( 2 ; pbtcH₅=5‐phosphonatophenyl‐1,2,4‐tricarboxylic acid, 2,2′‐bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline), with layer structures are reported. Compound 1 contains O‐C‐O and O‐P‐O bridged tetramers of Co₄, which are further connected by pbtcH^4? units to form a layer. In compound 2 , the cobalt tetramers made up of water‐bridged Co₂ dimers and O‐P‐O linkages are connected into a layer by pbtcH^4? units. Upon dehydration, compounds 1 and 2 experience single‐crystal‐to‐single‐crystal (SC–SC) structural transformations to form [Co₂(2,2′‐bpy)₂(pbtcH)] ( 1 a ) and [Co₂(pbtcH)(phen)₂] ( 2 a ), respectively. The process is reversible in each case. Notably, a breathing effect is observed for 1 , accompanied by pore opening and closing due to the reorientation of the coordinated 2,2′‐bpy molecules. The transformation was also monitored by in situ IR measurements. Magnetic studies reveal that antiferromagnetic interactions are mediated between the magnetic centers in compounds 1 and 1 a , whereas ferromagnetic interactions are dominant in compound 2 .     

关于歌唱中"呼吸"问题的几点思考

呼吸是人体发声的动力和源泉 ,也是歌唱艺术的基础 ,科学的发声方法离不开正确的呼吸运用。每一位学习声乐的音乐爱好者 ,必须要对歌唱的呼吸有一个正确的认识。用科学的理论来指导声乐实践 ,才能在声乐学习中取得明显的进步     

Lattice vibrational properties of uranium pnictides

Lattice vibrational properties of uranium pnictides have been studied using breathing shell model (BSM) which includes breathing motion of electrons of the U-atoms due tof−d hybridization. The phonon dispersion curves of U-pnicitides calculated from the present model agree reasonably well with the measured data. A comparison has been made between BSM and our results reported earlier obtained from three-body force rigid ion model to reveal the importance of the short-range electron-phonon interactions in these compounds. We also report, for the first time, the two phonon density of states and specific heat for these compounds.     

呼吸声分类技术研究及检测系统设计*

患有呼吸问题的病人由于呼吸道腺体不受意识控制、异物或者其本身肺部病变等原因会出现呼吸异常。医护人员通过病人的呼吸状况可以找寻和分析病人出现这种呼吸状况的原因。而以往呼吸声的诊断方式是专业的医护人员通过使用听诊器对病人进行肺部听诊。但是听诊的结果取决于医护人员的经验与相关参数。在初级诊断治疗阶段,初级医生识别听诊声的效率以及准确率很低,一般从20%到80%不等。因此会存在10%到20%的高误诊率（漏诊、错诊和延误）。本文提出了一种利用PVDF薄膜传感器提取语声特征的检测系统,该检测系统根据病人发出声音的不同,提取呼吸声特征值判断病人的呼吸状况。通过PVDF传感器采集的微弱呼吸声再经过KNN算法分类之后其识别率可达90.6%,对于细分种较类多的湿罗声,其识别率在80.2%左右。综上表明相比于传统听诊方式通过PVDF传感器采集识别的结果具有更高的准确性和可靠性,其判断呼吸状况的结果可以为医护人员提供参考,更好的为患有呼吸疾病的病人提供监测。     

Collective modes in the generator coordinate method

Using the harmonic version of the generator coordinate method, and Skyrme interaction, the frequencies of the isoscalar breathing and quadrupole modes are related to the relevant incompressibility coefficients. The possibility of extending this to spin modes is also examined. It is found that a spin incompressibility coefficient is negative for a particular set of Skyrme parameter for⁴He. Other sets produce low positive values and these in turn could imply a relatively low lyingS=2,T=1 state. The replacement of the three-body term by the density-dependent one, suggested by Chang provides a cure for this pathology.     

A Simple Theoretical Model for Ring and Nanotube Radial Breathing Mode

The radial breathing modes (RBMs) of (MgO)_n and (BeO)_n rings (n=3-10) were calculated using the density functional theory at B3LYP/6-31G(d) level. It was found that for large rings, the radial breathing mode (RBM) frequency was inversely proportional to the centre diameter, but the variation of bond length may lead to deviations from a linear behavior. The deviations caused by inverse cubic term of diameter and variation of bond length, became dramatic with the decrease of ring diameter. From the point of chemical bond view, using one-dimensional harmonic oscillator and the method of cascade and parallel connection of “springs”, the linear relation and deviations were explained. The model can be applied to nanotubes.     

On the determination of diameter distribution in multi‐wall carbon nanotubes by Raman spectroscopy: issues related to excitation laser energy

Multi‐wall carbon nanotubes (MWCNTs) produced by the arc discharge between two graphite rods in liquid nitrogen have been investigated with the use of Raman spectroscopy and transmission electron microscopy (TEM). The effects of the applied voltage on the structural properties of the produced MWCNTs have been observed, in particular, as it concerns the size of the innermost and outermost diameters. The apparent discrepancies observed between the Raman and TEM results are explained through the observation of a selective response of the MWCNTs to the excitation laser energy in Raman spectroscopy, similar to the case of single‐wall CNTs. Electronic structure calculations correlate such behavior with optical transitions, in the presence of strong electronic localizations, spatially confined in a few neighboring walls. Copyright © 2011 John Wiley & Sons, Ltd.     

非线性呼吸行为对带横向裂纹Jeffcott转子稳定性的影响

在分析现有力学模型局限性的基础上,考虑转子在失稳转速附近复杂的涡动状态,构建了不依赖于重力占优假设的含横向裂纹的Jeffcott转子的通用运动方程和一种拟合的裂纹呼吸模型。根据Floquet稳定性理论,用打靶法分析了该裂纹转子模型运动的稳定性。结果表明,刚度相对变化量、系统阻尼、裂纹相位角等系统参数对模型的运动稳定性都有较大影响,特别是裂纹相位角对稳定性的影响很复杂;在临界转速附近,裂纹的非线性呼吸行为可以提高转子的稳定性,且改变了失稳发散的行为;在亚临界转速附近,裂纹的非线性呼吸行为会降低转子的稳定性,使周期运动发生结构失稳。     

试论网球运动与呼吸

竞技网球运动正向着力量化方向发展,比赛日趋紧张、扣人心弦,运动员如何利用、发挥所有的积极因素去取得主动,并发挥身体和心理的极限,成为赢得胜利的关键．呼吸作为人体的基本新陈代谢功能在网球运动中同样起到了至关重要的作用,它对动作的合理性、爆发力以及比赛中的心理、生理调节都发挥了重要的作用．建议在平时的训练中增加对呼吸与技术、体能相结合的练习,从而提高运动成绩．     

BaBi1-xPbxO3体系的物理性质研究

采用固态反应法制备了一系列BaBi1-xPbxO3（x：0～1）多晶并测定了其晶体结构和相应的物理性质．粉末法测得的X射线衍射所得的晶体结构与粉末中子衍射结果一致，晶体经历了从单斜晶系（O≤x〈0．1）、到正交晶系（0．1≤x〈0．65）、再到四方晶系（0．65≤x〈0．9）、最后到正交晶系（0．9≤x≤1．0）的转变．发现随着四价阳离子铅对铋的掺杂替代导致晶胞参数在半导体区域减小，而在超导区域振动变化，这归结于Bi^3＋和Bi^5＋被Pb^4＋的取代和呼吸模型Bi（Bb）O6的作用，从而证明了Bi两种价态的存在．电阻率的测量结果表明样品的电性与晶体结构和生长环境紧密相关，但氧缺陷不是主要因素．最佳掺杂区在x=0．75，其超导临界温度约为9K．掺杂区0≤x≤0．3的样品既可用本征半导体解释，也可用3D变程跃迁解释．在半导体区用3D变程跳跃解释时，lnρ～T^-1／4的斜率连续减小，说明掺杂改变了态密度或定域化长度．样品的金属一半导体转变可用交叠能带解释．拉曼光谱的测量结果表明改变入射激光的频率并不影响各拉曼峰的强度．随Pb的掺杂，BiO6八面体的呼吸模数逐渐减少，同时晶体的无序程度增强．超导温度与Bi（Bb）O6模的形变势的强弱无关，但受其频移的影响．