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21.
Consider an elastic thin three-dimensional body made of a periodic distribution of elastic inclusions. When both the thickness of the beam and the size of the heterogeneities tend simultaneously to zero the authors obtain three different one-dimensional models of beam depending upon the limit of the ratio of these two small parameters.  相似文献   
22.
This paper is our attempt, on the basis of physical theory, to bring more clarification on the question “What is life?” formulated in the well-known book of Schrödinger in 1944. According to Schrödinger, the main distinguishing feature of a biosystem’s functioning is the ability to preserve its order structure or, in mathematical terms, to prevent increasing of entropy. However, Schrödinger’s analysis shows that the classical theory is not able to adequately describe the order-stability in a biosystem. Schrödinger also appealed to the ambiguous notion of negative entropy. We apply quantum theory. As is well-known, behaviour of the quantum von Neumann entropy crucially differs from behaviour of classical entropy. We consider a complex biosystem S composed of many subsystems, say proteins, cells, or neural networks in the brain, that is, S=(Si). We study the following problem: whether the compound system S can maintain “global order” in the situation of an increase of local disorder and if S can preserve the low entropy while other Si increase their entropies (may be essentially). We show that the entropy of a system as a whole can be constant, while the entropies of its parts rising. For classical systems, this is impossible, because the entropy of S cannot be less than the entropy of its subsystem Si. And if a subsystems’s entropy increases, then a system’s entropy should also increase, by at least the same amount. However, within the quantum information theory, the answer is positive. The significant role is played by the entanglement of a subsystems’ states. In the absence of entanglement, the increasing of local disorder implies an increasing disorder in the compound system S (as in the classical regime). In this note, we proceed within a quantum-like approach to mathematical modeling of information processing by biosystems—respecting the quantum laws need not be based on genuine quantum physical processes in biosystems. Recently, such modeling found numerous applications in molecular biology, genetics, evolution theory, cognition, psychology and decision making. The quantum-like model of order stability can be applied not only in biology, but also in social science and artificial intelligence.  相似文献   
23.
A new star-shaped molecule StOF-Br_3 containing oligofluorenes and halogen atoms(Bromine) has been synthesized and studied by Scanning Tunneling Microscopy(STM) at the highly oriented pyrolytic graphite(HOPG) surface.We have obtained the high-resolution self-assembled STM images,from which the highly ordered and closely packed non-porous arrangements of the StOF-Br_3 molecular selfassemblies at the heptanoic acid/HOPG surface could be observed.The molecular models and selfassembled StOF-Br_3 architectures have been given in the following text.Besides,we have also figured out the surface free energy by the density functional theory(DFT) calculation,which proved that the halogen...halogen interaction was strong enough to stabilize the ordered molecular self-assemblies.This work verifies the existence of bromine...bromine interactions,and meanwhile provides a kind of effective approach for quickly building ordered molecular nanoarchitectures with large areas and different geometries.  相似文献   
24.
One of the most important multipartite entangled states, Greenberger–Horne–Zeilinger state (GHZ), serves as a fundamental resource for quantum foundation test, quantum communication and quantum computation. To increase the number of entangled particles, significant experimental efforts should been invested due to the complexity of optical setup and the difficulty in maintaining the coherence condition for high-fidelity GHZ state. Here, we propose an ultra-integrated scalable on-chip GHZ state generation scheme based on frequency combs. By designing several microrings pumped by different lasers, multiple partially overlapped quantum frequency combs are generated to supply as the basis for on-chip polarization-encoded GHZ state with each qubit occupying a certain spectral mode. Both even and odd numbers of GHZ states can be engineered with constant small number of integrated components and easily scaled up on the same chip by only adjusting one of the pump wavelengths. In addition, we give the on-chip design of projection measurement for characterizing GHZ states and show the reconfigurability of the state. Our proposal is rather simple and feasible within the existing fabrication technologies and we believe it will boost the development of multiphoton technologies.  相似文献   
25.
 固体氧化物燃料电池的翘曲会影响电极-盖板界面的接触情况,从而影响电化学性能,对相关制造工艺提出了很大的挑战.为了分析燃料电池平面度对放电过程的影响,揭示其潜在的风险,我们建立了两个基于有限元法的仿真模型,对考虑平面度缺陷的燃料电池封装和放电进行分析.在对固体氧化物燃料电池进行平面度测量的基础上,首先建立了具有真实燃料电池翘曲特性的几何模型,分析封装过程中接触压力的分布情况.然后将接触电阻的仿真结果导入到三维多物理场耦合模型中,模拟具有平面度缺陷的燃料电池电化学性能.计算结果展示了燃料电池两侧封装过程中接触压力的分布情况.通过对比有接触电阻和无接触电阻的燃料电池电流密度,分析了电池与盖板的接触对放电过程的影响.结果表明,燃料电池的凹陷面较难达到满意的接触状态,需要比凸起面更大的封装压力.燃料电池表面接触电阻的变化将引起电流传导路径的变化,产生局部高电流或低电流.这项工作强调了在燃料电池中保持均匀分布的接触电阻的重要性,为今后的优化工作奠定了基础.  相似文献   
26.
王铮  刘骁 《应用声学》2020,39(6):868-875
采用超声水浸聚焦斜入射方式进行小棒材表面、近表缺陷检测时,声波在水/棒和棒/缺陷界面会发生反射、折射、散射、衍射及波形转换等一系列物理变换。此时缺陷可检性对声波入射条件十分敏感,常出现由于检测条件设置不当而导致缺陷漏检、误检的情况。为解决这一问题,本文针对小棒材超声斜入射检测中的主要参数——入射角和水距,开展声场及缺陷声响应仿真,研究检测参数对不同部位缺陷检测能力的影响,并对仿真结果进行试验验证。通过研究得到了检测水距、入射角度对缺陷检测能力的影响,并得到最优检测条件。试验验证结果表明研究制定的检测方案可有效检测出表面、近表面裂纹缺陷。  相似文献   
27.
In this study lanthanum trilactate was prepared by neutralization reaction of lactic acid and lanthanum oxide, purified and identified by X-ray powder diffraction. Infrared spectra (Mid-IR region 4000–650 cm−1) and Raman spectra (Stokes region 4000–100 cm−1) of the high quality crystalline samples have been recorded and presented for the first time. For comparison DFT calculations were performed using Gaussian 09 D.01 and agreement between predicted and measured spectral data has been achieved. Acquired information can be utilized for substance identification for example in various industrial applications or in biological systems.  相似文献   
28.
以聚苯乙烯-聚4-乙烯基吡啶(PS-b-P4VP)嵌段共聚物作为研究对象,采用DMF作为退火溶剂,以原子力显微镜(AFM)和透射电子显微镜(TEM)为表征手段,研究了溶剂退火后期溶胀薄膜中溶剂的去除速度对于薄膜相形貌的影响,发现通过改变溶剂去除速度可以有效的调控薄膜中的形貌.当薄膜厚度为35 nm时,DMF的快速挥发会导致薄膜中形成以PS为分散相的反转柱状相结构,当降低溶剂的挥发速度时,薄膜中形成了以PS为分散相的环状形貌,当进一步减缓挥发速度时,薄膜中将形成台阶状的片层结构;然而当薄膜厚度为55 nm时,溶剂退火后期薄膜中形成的是以P4VP为分散相的正常柱状相结构,在相同溶剂去除速度条件下薄膜相形貌变化较小.  相似文献   
29.
价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得(S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得(S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。  相似文献   
30.
Controllable phase segregation adjustment for immiscible polymer blends has always been tough, which hinders the development of amphiphilic antifouling coatings from more accessible blends. Herein, methacrylated poly(dimethylsiloxane) (PDMS‐MA) was synthesized and mixed with poly(ethylene glycol)methylether methacrylate (PEG‐MA). It was interestingly discovered that these PDMS‐MA/PEG‐MA blends displayed upper critical solution temperatures (UCST) due to thermo‐induced conformational change of PEG‐MA and the UCST changed with PDMS‐MA/PEG‐MA mass ratios. Micro‐/nano‐phase segregation, nanophase segregation, or homogenous morphology were therefore achieved. These PDMS‐MA/PEG‐MA blends with different mass ratios were UV‐cured under varying temperatures to fabricate coatings. Their surface morphology and wettability are readily adjusted by phase segregation. For the first time, highly hydrophilic surface was achieved for coatings with microphase segregation because of the exposure of PEG‐rich domains, which exhibited an enhanced protein resistance against bovine serum albumin (BSA). Anti‐bacterial performance (Shewanella loihica) was also observed for these PDMS/PEG coatings. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1612–1623  相似文献   
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