Computer generated holograms for carbon nanotube arrays.

Multiwalled carbon nanotubes are highly diffractive structures in the optical regime. Their metallic character and large scattering cross-section allow their usage as diffractive elements in Fraunhofer holograms. This work elaborates some important features of the far field diffraction patterns produced from periodic arrays of nanotubes. A theoretical approach for the interaction of arrays of nanotubes with light is presented and a computer generated hologram is calculated by means of periodical patterns. Based on the results, fabrication of carbon nanotube arrays (in holographic patterns) was performed. Experimentally measured diffraction patterns were in good agreement with the calculations.

Optical holograms based on carbon nanotubes

The size of pixels is one of the key limiting features in the state of the art of holographic displays systems. The resolution and field of view in these systems are dictated by the size of the pixel (the smallest light scattering element). We have demonstrated the utilization of carbon nanotubes (nanostructures) as the smallest possible scattering element for diffracting light in a highly controlled manner to produce a two dimensional image. An array of carbon nanotubes was elegantly patterned to produce a high resolution hologram. In response to the incident light on the hologram a high contrast image was produced. Due to the nanoscale dimension of the carbon nanotube array the image presented a wide field of view and high resolution. These results pave way towards the utilization of nanostructures for producing 3D holograms with wide field of view and high resolution. © 2013 IEEE.

Jetting of complex fluids

Recent results from a number of UK academic inkjet research studies advance the understanding of complex fluid jetting behavior and may be of interest to the wider digital fabrication community for the enhancement of inkjet printing applications. © 2013 Society for Imaging Science and Technology.

关于半导体电极上极化成份的分解和电极反应动力学参数的确定

电极动力学在金属电极上已经发展得比较成熟，对半导体来说，由于电极反应的复杂性，还有不少问题比较模糊。其中之一是怎样根据表观的极化测量求得反映界面电荷转移的动力学参数。目前有关这方面的工作不多，还没有见到具体对极化成份进行分解以求解半导体电极反应的动力学系统的报导。本工作从一定的电极物理模型出发，在电化学测量的基础上结合电子计算技术，对这方面问题的研究提出了测量计算方法。本文提出的半导体电极的物理模型如图A所示。I，I_J, I_S, I_D, I_H均取阴极性电流方向为正，η则按电极电势的方向取阳极过电热为正，阴极过电势为负。模型中的J反映空间电荷层的Schottky结特性，其数学描述可概括（对n-型半导体）为：I_J = I_0[exp(-n_s/a)-1] I_0： 结的反向饱和电流。（a:k_T）/q或（RT）/F D反映界面电荷转移反应的特性，其数学描述适用Butler-Volmer方程：I_D = i~0[exp(-(1-β)n η_H)/a) - exp(βη-η_H/a)] i~0:交换电流。β：阳极传递系数 C_s，C_H分别表示空间电荷层和Helmholtz层的电容。R_B和R_l分别为半导体体内和溶液电阻。由于J，D二者特性不同，可以通过极化测量利用电子计算机加以鉴别。实验上针对电路主要是串联结构的特点，采用恒电流极化，利用恒电流恒电位仪实现一系列的电流阶跃（I_(K-1) I_K K = 1, 2, 3 ……）记录相应的电位随时间变化的响应曲线如图B所示。根据曲线各段的特点，利用电子计算机曲线拟合，分别求解有关参数。（1）在t = 0时，找出一系列不同I下的φ（I_K, t = 0）值，根据φ（I_K, t = 0) = φ(I = 0)-I_KR拟合求解φ（I = 0）， R。（2）找出一系列不同I下的稳态极化数据φ（I_K,t →∞），推导出电位随电流变化关系式，拟合求解I_0, j~0, β。（3）利用暂态过程的φ（I_K, t = 0) ～ t曲线，拟合求解每阶电位变化区间的C_s，C_H。由于在我们的电极模型中，D采取的是完整的Butler-Volmer表达式，没有作任何简化或近似，因而在数据处理和计算时，涉及隐式超越代数方程和隐式超越微分方程，无法通过一般解析法求解。为此我们把牛顿迭代法和Runge-Kutta法引入相应的曲线拟合计算程序中。这样做虽然计算上比较复杂困难，但方法的通用性更广泛。无论Helmholtz层处于线性极化，弱极化，或强极化区部同样适用。我们用BASIC语言编写了梯度法，线性化法联合使用的曲线拟合源程序及牛顿迭代法和Runge-Kutta法于程序。利用上述研究方法，对不同掺杂浓度的n-型GaAs电极在S~(2-)/S_x~(2-)体系中的电化学行为进行了研究。求解的电荷转移反应的动力学参数I_0, i~0, β分别在7.27 * 10~(-8) - 4.66 * 10~(-1) A/cm~2, 2.08 * 10~(-6)-4.62 * 10~(-6)A/cm~2, 0.70 - 0.78的范围之内。并于Pt电极连同一体系中的i~0，β进行了比较。i_（半导体）~0 < i_（导体）~0。但β在二种材料上差别不大。将半导体电极极化分解为空间电荷层极化和Helmholtz层极化两部分。测量了空间电荷层电学及Helmholtz层电容与电极电位的关系。从实际测量中证明，本文提出的电极模型比较恰当的反映了半导体电极的特性，本工作的测量和拟合计算方法对研究半导体电极行为是一种可行的方法。

落叶松毛虫防治咨询专家系统

落叶松毛虫是东北林区主要害虫之一，它对松林可以造成毁灭性的破坏，因此，采取及时且必要的综合防治措施，可以带来显著的经济和生态效益。本文依据害虫综合管理的指导思想，采用计算机人工智能程序模型，构建了落叶松毛虫防治咨询专家系统。 落叶松毛虫防治咨询专家系统主要由推理机、知识库、数据库、知识获取机制和用户界面等部分组成。其中知识库和推理机是系统的核心部分。在知识库设计中充分考虑了落叶松毛虫防治的复杂性，结合具体的限定条件，如危害特征、自然环境、地形地貌、害虫的生长阶段等，将知识存储在数据库中形成专家数据库；利用数据库查询语言SQL语句设计了系统的推理机，采用正向推理的方式，增强了知识库的可扩展性和可维护性；知识获取机制面向林业专家，实现知识的获取以及知识库的修改、扩充等任务；数据库用来存放落叶松毛虫的基本信息，用户可以通过数据库来获得落叶松毛虫相应的咨询信息。 落叶松毛虫防治咨询专家系统的目标为：（1）对落叶松毛虫的基本信息、行为特征、生理和生态学特征以及防治方法和施药方法等进行存储和查询。（2）正向推理方式保证专家系统在运行时能方便地选择问题，实现智能推理过程。（3）易用的知识维护。 该系统主要有以下几方面的功能和特点：（1）该系统本着害虫综合管理的指导思想，以落叶松毛虫的种群动态为理论基础，充分考虑不同林地环境条件下的自然控制因素，根据环境、气候和害虫本身的条件推出更加合理的结论，尽量采用生物防治，必要时采用化学防治；（2）系统可向用户提供多种可行的防治方案，经营者可以根据当时当地的实际情况作出决定；（3）系统使用方便；（4）系统具有显示、打印、通过Internet浏览获取信息、显示推理解释等功能。 另外，本文对落叶松毛虫专家系统又进行了有效的评估，评估对象分为三个组别：领域专家、森保人员以及学生。三组人员分别针对系统实用性、友好性、系统提问的简洁程度以及可学习性给出等级分数。通过评估结果，最终认定该系统是可以信赖的。 本系统以落叶松毛虫防治领域专家的经验和知识为基础，有效地将计算机技术和森保专家的知识结合在一起，集落叶松毛虫信息存储浏览、查询、专家系统于一体，对于缓解森林保护专家和人员的不足，提高落叶松毛虫虫害的防治能力，加快科技成果的转化具有重要的意义。

Investigation of facilitated ion-transfer reactions at high driving force by scanning electrochemical Microscopy

The kinetics of facilitated ion-transfer (FIT) reactions at high driving force across the water/1,2-dichloroethane (W/DCE) interface is investigated by scanning electrochemical microscopy (SECM). The transfers of lithium and sodium ions facilitated by dibenzo-18-crown-6 (DB18C6) across the polarized W/DCE interface are chosen as model systems because they have the largest potential range that can be controlled externally. By selecting the appropriate ratios of the reactant concentrations (Kr c(M)+/c(DB18C6)) and using nanopipets as the SECM tips, we obtained a series of rate constants (k(f)) at various driving forces (Delta(O)(W) phi(ML+)(0') - Es, Delta(O)(W) phi(ML+)(0') is the formal potential of facilitated ion transfer and Es is the potential applied externally at the substrate interface) based on a three-electrode system. The FIT rate constants k(f) are found to be dependent upon the driving force. When the driving force is low, the dependence of 1n k(f) on the driving force is linear with a transfer coefficient of about 0.3. It follows the classical Butler-Volmer theory and then reaches a maximum before it decreases again when we further increase the driving forces. This indicates that there exists an inverted region, and these behaviors have been explained by Marcus theory.

Study of electron-transfer reactions across an externally polarized water/1,2-dichloroethane interface by scanning electrochemical microscopy

A novel method to study electron-transfer (ET) reactions between ferrocene in 1,2-dichloroethane (DCE) and a redox couple of K3Fe(CN)(6) and K4Fe(CN)(6) in water using scanning electrochemical microscopy (SECM) with a three-electrode setup is reported. In this work, a water droplet that adheres to the Surface of a platinum disk electrode is immersed in a DCE solution. The aqueous redox couple serves both as a reference electrode on the platinum disk and as an electron donor/acceptor at the polarized liquid/liquid inter-face. With the present experimental approach, the liquid/liquid interface can be polarized externally, while the electron-transfer reactions between the two phases can be monitored independently by SECM. The apparent heterogeneous rate constants for the ET reactions were obtained by fitting the experimental approach curves to the theoretical values. These rate constants obey the Butler-Volmer theory i.e., them, are found to be potential dependent.

Study of electron transfer across the liquid/ice-like matrix interface by scanning electrochemical microscopy

In this work, we report the findings of a study on scanning electrochemical microscopy (SECM) to investigate the interfacial electron-transfer (ET) reaction between the 7,7,8,8-tetracyanoquinodimethane radical anion (TCNQ(.-)) in 1,2-dichloroethane and ferricyanide in an ice-like matrix (a mixture of insulting ice and conductive liquid) under low temperatures. Experimental results indicate that the formed liquid/ice-like matrix interface is superficially similar in electrochemical characteristics to a liquid/liquid interface at temperatures above -20 degreesC. Furthermore, imaging data show that the surface of the ice-like matrix is microscopically flat and physically stable and can be applied as either a conductive or an insulting substrate for SECM studies. Perchlorate ion was selected as the common ion in both phases, the concentrations of which controlled the interfacial potential difference. The effect of perchlorate concentration in the DCE phase on interfacial reactions has been studied in detail. The apparent heterogeneous rate constants for TCNQ(.-) oxidation by Fe(CN)(6)(3-) in another phase under different temperatures have been calculated by a best-fit analysis, where the experimental approach curves are compared with the theoretically derived relationships. Reaction rate data obey Butler-Volmer formulation before and after the freezing point, which is similar to most other known cases of ET reactions at liquid/liquid interfaces. However, there is a sharp change observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition. At temperatures below -20 degreesC, surface-confined voltammograms for the reduction of ferricyanide were obtained, and the ice-like matrix became an insulating one, which indicates that the aqueous phase is really a frozen phase.

Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

In this work, we report the reverse electron transfer reaction between TCNQ in 1, 2-dichloroethane (DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effects of the concentrations of TBA(+) and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.

应用扫描电化学显微镜研究水/1,2-二氯乙烷界面上离子诱导的电子转移反应

应用扫描电化学显微镜和微电极技术研究了水 / 1,2 二氯乙烷界面上的反向电子转移反应 .分别以K4 Fe(CN) 6和 7,7,8,8 四氰代二甲基苯醌 (TCNQ)作为水相和有机相的电活性物质 ,通过选择合理的共同离子 (TPAs+与TBA+)来控制界面电位差 ,实现了这一在热力学上通常不可能实现的反向电子转移反应 .利用扫描电化学显微镜给出的正负反馈信息 ,研究了界面电位差驱动的液 /液界面上的电子转移反应 ,并进一步得到了在不同的共同离子浓度比时 ,此异相界面反应速率常数kf 为 1 3× 10 -31 8× 10 -2 cm/s(共同离子为TBA+)和 2 5× 10 -32 8× 10 -2 cm/s(共同离子为TPAs+) .验证了此反应速率常数kf 是由界面电位差所决定的 .在此实验条件下 ,此反应速率常数kf 与界面电位差的关系遵守Butler Volmer公式 .

高温高压下水热体系中黄铁矿-金原电池的腐蚀电化学原位测量研究

水流体-导电性矿物相互作用是自然界中水流体-固体相互作用的重要组成部分，是许多矿床形成和演化的核心过程。迄今为止，绝大多数地质和地球化学家们对导电性矿物在水流体中的溶解机制普遍存在模糊的认识，认为水流体中导电性矿物的溶解和定位是一种简单的化学溶解和沉淀或简单的氧化溶解和还原定位过程，而实质上导电性矿物（组合）在水流体中的溶解是一种由电极电位差驱使下的类似于金属腐蚀的复杂电化学过程。当具有不同电极电位的矿物在溶液中相互接触，就会形成短路原电池发生电化学腐蚀。其中，电极电位低的矿物作为原电池的阳极，其溶解会加剧，而电极电位高的矿物作为原电池的阴极，其溶解会受到抑制。鉴于前人对水流体-导电性矿物相互作用的腐蚀原电池反应机理的模糊认识，本论文工作基于腐蚀原电池观点对高温高压条件下NaCl水流体体系中黄铁矿与金之间的原电池反应进行了研究。 在本工作中，作者与所在的研究小组一道，首先自行研制了一套可用于高温高压水热体系中导电性矿物腐蚀电化学原位测量的高压釜反应装置。该装置主体部件选用在高温高压下具有高强度、抗腐蚀等优良性能的工业纯钛制成。在该装置中，通过将热电偶直接插入高压釜釜腔内，成功地实现了釜内流体温度的准确测量和精确控制。对高压釜不同部位的测温结果表明，沿高压釜的径向与轴向均存在显著的温度梯度，其中釜塞保护锥体处的温度比釜内流体的温度低约8℃，釜外壁中心处与釜内的温度差约10℃；对400℃保温条件下釜内流体温度的直接测量表明，釜内温度波动小于0.5℃。在该装置中，通过将脆性导电性矿物制作成锥形电极，采用耐高温无机绝缘材料制作密封部件，利用锥体自紧式密封技术，成功地解决了脆性电极和电极引线的高压密封与高温绝缘问题；通过引入另一根辅助性的矿物电极引线，成功地解决了原位监测实验过程中矿物电极与引线接触处是否进水的难题，确保了实验的可信度。可行性试验结果表明，该方法不仅可用于高温高压下水流体-导电性矿物，而且可广泛用于水流体-金属间相互作用的腐蚀电化学原位测量研究。 利用上述自行研制的腐蚀电化学实验装置，本工作对高温高压（250-400℃；10-35 MPa）NaCl水流体体系中黄铁矿-自然金原电池的热力学和动力学进行了实验研究。原位测量结果表明： （1）黄铁矿-金原电池的腐蚀电流变化与其开路电压的变化一致； （2）汽-液平衡条件下，黄铁矿-金原电池的开路电压和腐蚀电流在液相中比在汽相中要大； （3）在温度为400 C、压力远离临界点的过热蒸气和超临界区域，压力在实验研究的范围内（10-35 MPa）对黄铁矿-金原电池的开路电压和腐蚀电流均无显著的影响，随压力的增加两者仅略有增大，但当温度压力跨越临界点时，包括温压从汽-液平衡曲线同时进入超临界区以及温度恒定在400 C、压力跨越临界点时，黄铁矿-金原电池的开路电压和腐蚀电流在临界点附近均发生突变。 （4）在本工作中实验的温度、压力和水流体体系条件下，由黄铁矿与金构成的原电池在大多数情况下黄铁矿为阳极，因此在原电池短路时黄铁矿在水流体中发生氧化溶解，而金则为阴极，在原电池短路时金的溶解受到保护，仅在个别狭窄的温度压力范围内情况才相反。 上述原位测量结果与电极表面水流体的性质以及黄铁矿和金的能带结构密切相关，运用混合电位理论、Butler-Volmer方程以及半导体电化学的波动能级模型对实验结果能进行很好的解释。

硫化物矿物原电池腐蚀实验研究与应用启示

作为自然界最常见、可开发的矿物之一，硫化物矿物通常具有半导体性质，在溶液的作用下，必然发生原电池腐蚀。硫化物矿物原电池效应广泛存在并影响湿法冶金(如磨矿、浮选和浸出)、次生硫化物矿物过程、地电化学勘探、重金属离子污染和酸性矿山排水污染和治理等方面。 以前对硫化物矿物腐蚀研究多见于静止的溶液体系，少见于流动溶液体系，而实际情况是硫化物矿物经常处于流动溶液体系中。以矿山环境为例，硫化物矿物经常处于流动的地表水，地下水和雨水淋漓的环境体系中。因此，在流动体系中进行硫化物矿物原电池腐蚀实验研究，无疑对矿山环境治理有着直接的指导作用。另一方面，以前对于硫化物矿物原电池腐蚀的研究多是在无应力作用的条件下进行的，而事实上，无论是人类在开采利用硫化物矿物资源上，还是硫化物矿物本身在自然界的演化进程中，应力作用无时不在，无处不有。硫化物矿物应力原电池也无时不在，无处不有。应力作用下，应变能转化为电化学能，从而改变硫化物矿物的电极电位，必将进一步对硫化物矿物的原电池腐蚀产生重要影响。考察应力作用下的硫化物矿物原电池腐蚀，一方面可以为硫化物矿物的湿法冶金提供实验依据；另一方面，它将为硫化物矿物的元素活化、迁移、浓集和定位等各种地球化学作用解释提供理论指导。 鉴于硫化物矿物原电池腐蚀实验研究的重要意义以及前人对硫化物矿物原电池腐蚀研究在流动体系和应力作用等领域的研究空白，本论文展开了对上述领域的原电池腐蚀实验研究。 在本工作中，我们设计了一套用于溶液静止和溶液流动条件下的硫化物矿物原电池腐蚀实验装置。在流动条件下，对处在不同溶液组分(Na+、Cu2+、Fe3+)、浓度和流速的黄铁矿-黄铜矿、黄铁矿-方铅矿及应力残余黄铁矿-方铅矿原电池腐蚀进行了实验研究；设计了一套用于溶液静止条件下的硫化物矿物应力原电池腐蚀实验装置。展开了在不同溶液组分(Na+、Fe3+)及弹性轴压应力条件黄铁矿和黄铜矿腐蚀电位下的Tafel曲线及交流阻抗谱实验；在不同溶液组分(Na+、Fe3+)及差应力条件下黄铁矿-黄铜矿原电池混合电位下的Tafel曲线及交流阻抗谱实验。 实验结果表明： (1) 溶液中惰性离子(Na+)浓度的改变对原电池腐蚀电流密度和混合电位无明显影响；溶液中氧化性离子(Cu2+、Fe3+)浓度增大，原电池的腐蚀电流密度和混合电位增大。但是，当黄铁矿-黄铜矿原电池中氧化性离子为Cu2+时，增大Cu2+浓度，腐蚀电流密度先增大后减小，最后增大。 (2) 本实验条件下，溶液流速越大，腐蚀电流密度越大，混合电位增大。 (3) 应力残余黄铁矿由于残余应变能的缘故，其电极电位比处在相同条件的溶液下的方铅矿电极电位更低，应力残余黄铁矿-方铅矿原电池腐蚀情况与无应力的黄铁矿-方铅矿原电池腐蚀情况不同。 (4) 弹性轴压应力下，黄铁矿、黄铜矿电极电位和弹性轴压应力呈较好的负线性关系；黄铁矿、黄铜矿弹性轴压应力越大，腐蚀电位越小，腐蚀电流密度越大；电化学阻抗谱测试等效电路拟合的电极电荷传递电阻越小，极化电阻越小，双电层的离子迁移电阻越小，弥散效应越严重。 (5) 差应力作用下的黄铁矿-黄铜矿原电池腐蚀： 黄铜矿阳极弹性轴压应力越大，腐蚀电位越小，腐蚀电流密度越大；电化学阻抗谱测试等效电路拟合的电极电荷传递电阻越小，极化电阻越小，双电层的离子迁移电阻越小，弥散效应越严重。 黄铁矿阴极弹性轴压应力越大，腐蚀电位越大，腐蚀电流密度越小；电化学阻抗谱测试等效电路拟合的反应电阻越大，极化电阻越大，双电层的离子迁移电阻越大，弥散效应越轻微。 上述流动体系下的硫化物矿物原电池腐蚀结果可用Butler-Volmer方程结合原电池模型和双电层结构很好地解释；应力原电池腐蚀结果可用硫化物矿物半导体的热力学势、电化学势、力学应变能、结合原电池模型和双电层结构很好地解释。

Risorse intangibili e imprese familiari: principali contributi sul tema e nuove prospettive di ricerca

Intangible resources are the distinctive factors for the success of businesses (Barney, 1991) and for this reason the literature has paid particular attention to this issue (Barney, 1991; Hall, 1992,1993; Carmeli, 2004; Galbreath, 2005; Hayton, 2005; Norman, Butler, Ranft, 2013). With this thesis I will analyze existing studies on the subject with particular reference to family businesses - ideal forum for the spread of specific intangibles (Ward, 1988; Habbershon, Williams, 1999; Sirmon & Hitt, 2003; Huybrechts et al., 2011; Rose, Howorth & Discua Cruz, 2014), in order to identify the main areas of research and new research perspectives. Through a narrative review on the general theme of intangible resources, bibliometric analysis of the contributions that jointly address the intangibles and family businesses and co-citation analysis for the definition of the intellectual structure of the studies on the intangible resources in family firms is reached an in-depth study of the issue with relevant academic and practical implications.

Mexico coming into light

Boston University Theology Library