Evidence for a K<Superscript>π</Superscript> = 1/2<Superscript>+</Superscript> isomer in neutron-rich <Superscript>185</Superscript>Ta

In this paper we present for the first time the measured delayed neutron (DN) yields and time spectra from high-energy protons interacting with thick ^natPb targets. The 1GeV protons from the accelerator impinged on targets of different thicknesses producing a huge number of spallation-fission products, some of which can be DN precursors. After the beam is switched off, the DNs were detected with optimized ³He counter. The production yields of light DN precursors as ¹⁷N and “usual” fission products as ⁸⁷Br and ⁸⁸Br, which dominate the total DN activity, are obtained both for thin and thick targets. These new data are of great interest for the new generation high-power spallation targets based on liquid-metal technologies. Our findings also should help to constrain the physics models within the simulations codes.     

Stochastic Resonance in a Bistable System Subject to Dichotomous Noise

The stochastic resonance phenomenon in a bistable system subject to Markov dichotomous noise (DN) is investigated. Based on the adiabatic elimination and the two-state theories, the explicit expressions for the signal-to-noise ratio (SNR) and the spectral power amplification (SPA) have been obtained. It is shown that two peaks can occur on the curve of SNR versus the intensity of the DN. Moreover, the SNR is a non-monotonic function of the correlation time of the DN. The SPA varies non-monotonously with the strength of the DN. The dependence of the SNR on the frequency and the amplitude of the external periodic signal are discussed. The effect of the external frequency and the correlation time of the DN on the SPA are analyzed.     

Synthesis of Novel Double Network Hydrogels via Atom Transfer Radical Polymerization

Novel double network (DN) hydrogels were prepared via atom transfer radical polymerization (ATRP) of the first network using two different initiators, and followed by ultraviolet (UV) photo-initiated polymerization for the second network. The first networks of DN hydrogels were prepared by using two different initiators; one is a one-side initiator, and the other is a double-side initiator. The mechanical properties of various DN gels, such as water content and compressive strength, were studied. The network structure of the DN hydrogels was also characterized by dynamic light scattering. Thus, we demonstrated that the ATRP method is useful to control the network structure of the first network for DN gels. Extensive inhomogeneous structure of the first network was obtained by ATRP method and increased both the swelling degree and softness of DN gels.     

Aerodynamic parameters of across-wind self-limiting vibration for square sections after lock-in in smooth flow

The paper aims to identify the across-wind aerodynamic parameters of two-dimensional square section structures after the lock-in stage from the response measurements of wind tunnel tests under smooth wind flow conditions. Firstly, a conceivable self-limiting model was selected from the existent literature and the revisit of the analytical solution shows that the aerodynamic parameters (linear and nonlinear aerodynamic dampings Y₁ and ε, and aerodynamic stiffness Y₂) are not only functions of the section shape and reduced wind velocity but also dependent on both the mass ratio (m_r) and structural damping ratio (ξ) independently, rather than on the Scruton number as a whole. Secondly, the growth-to-resonance (GTR) method was adopted for identifying the aerodynamic parameters of four different square section models (DN1, DN2, DN3 and DN4) by varying the density ranging from 226 to 409 kg/m³. To improve the accuracy of the results, numerical optimization of the curve-fitting for experimental and analytical response in time domain was performed to finalize the results. The experimental results of the across-wind self-limiting steady-state amplitudes after lock-in stage versus the reduced wind velocity show that, except the tail part of the DN1 case slightly decreases indicating a pure vortex-induced lock-in persists, the DN2, DN3 and DN4 cases have a trend of monotonically increasing with the reduced wind velocity, which shows an asymptotic combination with the galloping behavior. Due to such a combination effect, all three aerodynamic parameters decrease as the reduced wind velocity increases and asymptotically approaches to a constant at the high branch. In the DN1 case, the parameters Y₁ and Y₂ decrease as the reduced wind velocity increases while the parameter ε slightly reverses in the tail part. The 3-dimensional surface plot of the Y₁, ε and Y₂ curves further show that, excluding the DN1 case, the parameters in the DN2, DN3 and DN4 cases almost follow a symmetric concave-up distribution versus the density under the same reduced wind velocity. This indicates that the aerodynamic parameters in the DN3 case are the minima along the density distribution.     

具有双网络结构高强度和形状记忆水凝胶

本文将形状记忆功能引入到双网络水凝胶设计之中.首先合成了聚乙二醇-聚丙烯酰氧乙基三甲基氯化铵/聚（丙烯酰胺-co-丙烯酸）（PEG-PDAC/P（AAm-co-AAc））双网络水凝胶,其中第一套网络由交联的聚乙二醇（PEG）链组成,包埋着聚电解质聚丙烯酰氧乙基三甲基氯化铵（PDAC）;第二套网络由丙烯酰胺（AAm）和丙烯酸（AAc）的共聚物交联组成,交联剂为N,N''-亚甲基双丙烯酰胺（MBAA）.结果表明,双网络水凝胶显示出高强度的特点,其断裂应力和韧性分别达到了0.9 MPa和3.8 MJ/m³.和传统地利用中性高分子作为柔软和韧性的第二套网络相比较,本文选择将具有弱电解质特性的丙烯酸单体引入到第二套网络中,利用丙烯酸与三价铁离子的络合作用,成功地赋予水凝胶在氧化环氧反应条件下的形状记忆功能.结果表明,只要巧妙地引入响应性单体,高强度和形状记忆这两种最重要的特性可以同时被引入到双网络水凝胶的设计之中.     

Preparation and properties of morphology controlled poly(2-hydroxyethyl methacrylate)/poly(N-vinyl pyrrolidone) double networks for biomedical use

Poly(2-hydroxyethyl methacrylate)/poly(N-vinyl pyrrolidone) (PHEMA/PVP) double networks (DN) were prepared using a sequential method by incorporating a second network of crosslinked PVP into PHEMA. We found that the distributions of the two networks can be regulated just by modulating the morphology of the first network, thus giving expected high water content of these gels. Fourier transform infrared (FTIR) spectroscopy and scanning electronic microscopy (SEM) were used to confirm the structure of the DN. The incorporation of more hydrophilic PVP enhanced swelling ability of these gels. Because of improved hydrophilicity, the PHEMA/PVP DN exhibited higher loading capability for water-soluble substance than that of pure PHEMA, while showed a slower release rate than corresponding HEMA/NVP copolymer hydrogel. It is suggested that the DN gels are potential biomaterials for wound dressing, medical implants and other drug delivery systems.     

指纹紫外光谱特性研究及变化规律分析

指纹的唯一性和终身不变性使得指纹可以验证一个人的身份信息,在生物识别领域具有广泛的应用。汗潜指纹对紫外线有着特殊的反射、散射以及荧光特性,所以可以利用紫外波段对汗潜指纹进行提取,并且不污染现场和目标样本。目前对紫外波段的指纹提取已经有着广泛的研究,但对指纹随时间变化的研究较少,一般都是通过化学方法测量汗潜指纹成份含量的变化。研究发现,指纹各个组成成份的紫外光谱特性不同,且这些成份随时间的挥发程度也不一致,利用多通道紫外成像系统对汗潜指纹进行凝视成像,发现各通道成像DN值随时间推移的变化程度并不一样,可通过研究各通道DN值的变化对指纹进行时间分析。首先,利用紫外光谱仪和氙灯,对汗液、酒精、食用油等几种手指容易接触的物质的反射光谱进行研究,得到了这些物质的反射光谱特性。然后,针对这几种类型的指纹,研制了一套多通道紫外成像设备,分别在240~280 nm（通道1）、280~315 nm（通道2）以及315~340 nm（通道3）三个紫外通道对其进行凝视成像,得到清晰的指纹图像,将指纹图像嵴线上码值最高的10个点的平均值进行比较,得到不同通道DN值与时间变化的关系。实验结果发现,汗潜指纹在紫外波段具有良好的成像特性,其成像DN值随时间的推移逐渐降低,其中240~280 nm的通道1中三个指纹在第七天的成像DN值分别降为第一天的0.62, 0.60和0.59;320~340 nm的通道2中三个指纹在第七天的成像DN值分别降为第一天的0.57, 0.61和0.60;340~420 nm的通道3中三个指纹在第七天的成像DN值分别降为第一天的0.56, 0.63和0.58。实验结果表明,不同类型的指纹在紫外波段的光谱特性并不一致,成像DN并不相同,且随时间的变化规律也不一样,但指纹成份的挥发具有一定的规律,成像DN值从第一天到第七天降低至60%左右,可以一定程度上反映指纹的挥发性质。结合紫外多通道成像系统,可以很好的研究指纹的变化规律,为刑侦探测中指纹研究提供了一个重要的手段。     

温度对4管像素结构CMOS图像传感器性能参数的影响

为了对4管像素结构CMOS图像传感器的空间应用提供可靠性指导,对4管像素结构的CMOS图像传感器进行了-40~80℃的变温实验,着重分析了样品器件的转换增益、满阱容量、饱和输出和暗电流等参数随温度的变化规律。实验结果表明,随着温度的升高,样品器件的转换增益从0.026 54 DN/e下降到0.023 79 DN/e,饱和输出从4 030 DN下降到3 396 DN,并且暗电流从22.9 e·pixel-1·s-1增长到649 e·pixel-1·s-1。其中器件转换增益的减小应主要归因于载流子迁移率随温度升高而下降使得像素后端读出电路增益降低;饱和输出的降低则是因为转换增益的降低,因为转换增益随温度变化对饱和输出的影响要大于满阱容量随温度变化对饱和输出的影响。     

The association between the antineoplastic drug daunomycin and iron. evidence for polynuclear aggregates

In contrast to literature data, at millimolar iron and daunomycin (DN) concentrations no solitary Fe(DN)₃ complexes are formed in appreciable amounts. The Mössbauer spectroscopic analysis revealed severe dependencies on temperature and on the metal ligand ratio. Two species can be discerned: exchange-coupled polynuclear aggregates, which are magnetically highly anisotropic and another superparamagnetic system, exhibiting much less magnetic anisotropy. The cooperative phenomena observed are attributed to stacking effects of daunomycin.     

耗散粒子动力学模拟方法在软物质体系研究中的一些进展与应用

软物质是指处于固体和理想流体之间的复杂态物质,主要包括聚合物、表面活性剂、液晶、胶体悬浮液、以及生物大分子等。软物质能够对外界微小的作用产生强烈的非线性响应,并展现出丰富的有序自组装相态。作为一种新颖的模拟技术,耗散粒子动力学方法非常适合在介观尺度上对软物质体系的复杂行为进行合理的描述。本文对耗散粒子动力学模拟方法的发展及一些应用进行了系统评述。耗散粒子动力学模拟方法体现了分子动力学与格子Boltzmann模型的优点,通过与其它理论模型（如Flory-Huggins理论、Smoothed particle hydrodynamics模型等）相结合,该方法能够在介观尺度上有效地研究聚合物熔体和溶液体系、生物膜及囊泡体系以及胶体悬浮液等体系的行为。这些研究结果,对新材料的研发、特殊材料的制备、以及材料加工条件的选择具有十分重要的科学意义和实际应用价值。     

凝聚态物理学中的基本概念

本文首先根据物质世界的层次化来说明凝聚态物理学在当今物理学中所处的地位,并阐述了复杂与简单的辨证关系,来说明为何这一学科至今仍然富有生命力;进而对这一学科的范围进行了讨论,强调了位形空间和动量空间中都存在多种类型的凝聚现象,而相应的凝聚体构成了这一学科的研究对象;还探讨了处理凝聚态理论问题的量子物理与经典物理方法有效领域的界限与分野;最终对此学科的发展历史进行回顾,并追溯和剖析了其概念全系的演变,     

Internet中的物理资源

对Internet中的物理资源进行了较系统的介绍，主要内容有：综合物理网站、物理期刊网站和物理教学网站，其中重点介绍了美国和欧洲主要国家的物理网站和物理期刊网站，利用这些物理站点，可以方便的进行文献检索、物理会议查询，物理教学相关资料的查询和世界各大学物理系的查询；可以方便快捷的了解当今世界各国的物理教学学科研的最新进展，文中对各个物理站点的使用方法都一一做了详细的介绍，以方便读者使用。     

Theory of the proximity effect in junctions with unconventional superconductors

We present a general theory of the proximity effect in junctions between diffusive normal metals (DN) and superconductors. Various possible symmetry classes in a superconductor are considered: even-frequency spin-singlet even-parity (ESE) state, even-frequency spin-triplet odd-parity state, odd-frequency spin-triplet even-parity (OTE) state and odd-frequency spin-singlet odd-parity state. It is shown that the pair amplitude in a DN belongs, respectively, to an ESE, OTE, OTE, and ESE pairing state since only the even-parity s-wave pairing is possible due to the impurity scattering.     

核能和物理学

本文分别讨论了实现裂变和聚变核能的利用与物理学各学科（核物理、中子物理、等离子体物理、磁流体力学、材料物理、热物理、剂量防护、堆物理）研究工作的相互促进关系。     

中国医学物理学的过去、现在与未来

医学物理（medical physics，MP）是把物理学的原理和方法应用于人类疾病的预防、诊断、治疗和保健的一门交叉学科，是物理学与医学实践相结合的一门独立的分支学科．它是研究人类疾病诊、治过程中的物理现象，并用物理方法表达这种现象．医学物理包括放射肿瘤物理（rsdiation oncdogy physics，ROP）、医学影像物理（medical imaong physics，MIP）、核医学物理（nuclear medicine physics，NMP），其他非电离辐射如核磁、超声、微波、射频、激光等物理因子在医学中的应用，和保健物理（heath physics，HP）等分支内容．医学物理学和生物医学工程学（biomedical engineefing，BME）是一对栾生的兄弟学科，分别从物理学的角度（前者）和工程学的角度（后者）研究人类疾病诊断、治疗及健康保健过程中的生命现象和采取相应的物理措施和工程手段。医学物理学与物理医学（physical medicine，PM）是完全两个不同的概念，前者是物理学的分支，后者是医学的分支．自上世纪60年代以来，中国医学物理学有了很大的进展，推动了中国现代放射肿瘤学、核医学和医学影像学的发展；成立了自己的学术组织，并成为国际医学物理组织（IOMP）的成员国组织．随着中国逐步奔入小康社会，为适应人民大众对健康的需求和现代化医院发展的需要，中国医学物理应该加快发展．     

Reflectionless tunneling at the interface between nanoparticles and superconductors

Interfaces between disordered normal (DN) materials and superconductors (S) are known to generate conductance peaks at zero-bias voltage (V) and magnetic field (B). Using molecularly linked Au nanoparticle films as the DN component, we find that superimposed on conductance peaks are oscillations that depend simultaneously on both V and B. Such correlated conductance oscillations are predicted by a "reflectionless tunneling" phenomenon but have not been observed in other DN-S systems. Length scales extracted from periods of conductance oscillation correlate well with film nanostructure.     

太空物理学当代前沿及其交叉特点

文章对21世纪太空物理学的发展趋势及其与物理学交叉的特点作了论述，主要内容包括：（1）太空物理学的地位和作用；（2）21世纪太空物理学的发展趋势和前沿问题；（3）物理学与太空物理学交叉的特点（包括太空物理探测与物理学的交叉，太空物理与等离子体物理的交叉，太空物理与高能物理的交叉，太空开发利用与物理学的交叉）。     

探究式物理实验的两条设计思路及案例

提供了两条设计探究式物理实验的思路,即选用学生熟悉的事例和传统的物理实验,设计成探究式物理实验.设计了5个探究式物理实验,并就此对教学给出了自己的体会.     

以科研工作介绍的融入促进大学物理教学

以亚毫米波天文学的科研工作情况介绍在大学物理教学实践中的融入为例,针对时下大学教师教学工作和科研工作的双重角色,就如何将教师最新的科研工作进展引入到大学物理的教学中,引导学生对于物理学实效性的认识,激发学生对于大学物理的兴趣和热爱,进而促进大学物理的教学效果,用一些具体的实例进行了说明.     

大学物理研究性实验探索

对笔者在物理实验教学过程中,所指导学生进行的一些具有创新性的研究性实验进行了探索、研究,归纳和总结,对学生进行研究性实验的情况进行了介绍,以供各位同仁师生参考。