微波辅助polyol法制备纳米金属镍及磁性研究

采用微波辅助polyol法成功地制备了直径范围在5～10nm、100～180nm的单分散Ni球,对其磁性进行了测量分析.用XRD和EDAX,接着用TEM和MFM分别对制备的样品进行测试,并用VSM和SQUID进一步讨论了铁磁/反铁磁的界面耦合效应.XRD显示该样品是面心立方结构,EDAX数据表明制备过程中镍球被轻微氧化,MFM和TEM观察结果显示样品金属镍是比较理想的球型,VSM测试结果表明Ni纳米球具有典型的铁磁性.     

单分散Ni球制备及Ni／NiO的磁性研究

使用微波辅助Poly方法制备了直径范围在100nm～180nm单分散的Ni球，用磁力显微镜（MFM）测其磁结构。进一步对Ni球表面氧化获得了高度球化的NicoreNiOshell结构，采用XRD，TEM，XPS和EDAX对其进行了测量分析，并用VSM和SQUID进一步讨论了铁磁／反铁磁的界面耦合效应。同时，估算了磁性交换偏置耦合场与颗粒尺寸的关系。     

Spine-shaped gold protrusions improve the adherence and electrical coupling of neurons with the surface of micro-electronic devices

Interfacing neurons with micro- and nano-electronic devices has been a subject of intense study over the last decade. One of the major problems in assembling efficient neuro-electronic hybrid systems is the weak electrical coupling between the components. This is mainly attributed to the fundamental property of living cells to form and maintain an extracellular cleft between the plasma membrane and any substrate to which they adhere. This cleft shunts the current generated by propagating action potentials and thus reduces the signal-to-noise ratio. Reducing the cleft thickness, and thereby increasing the seal resistance formed between the neurons and the sensing surface, is thus a challenge and could improve the electrical coupling coefficient. Using electron microscopic analysis and field potential recordings, we examined here the use of gold micro-structures that mimic dendritic spines in their shape and dimensions to improve the adhesion and electrical coupling between neurons and micro-electronic devices. We found that neurons cultured on a gold-spine matrix, functionalized by a cysteine-terminated peptide with a number of RGD repeats, readily engulf the spines, forming tight apposition. The recorded field potentials of cultured Aplysia neurons are significantly larger using gold-spine electrodes in comparison with flat electrodes.     

Contemporary Trends in Formwork Standards—A Case Study

One expression of the renewed attention gained recently by formwork for concrete is the current revision of formwork standards. This paper presents the new Israeli formwork standard as a case study for contemporary trends in formwork standardization. The main novelty in the new standard is its similar treatment of the design of temporary structures to that of permanent structures, resulting in the replacement of the traditional allowable-stress approach with the concept of limit-state design and partial safety factors. The paper presents this concept and discusses its applicability to formwork design. In addition, the paper highlights several other issues of a contemporary nature, which appear to be worth debate by standardization committee members from the industry and academia. In the course of the preparation of the new Israeli standard, American, European, and Australian standards and similar documents were closely studied; some comparisons of design and loading data that may affect construction safety and economy are also presented in this paper.     

Education in Construction Engineering and Management Built on Tradition: Blueprint for Tomorrow

Construction continues to be a significant part of the global economy and shapes the built environment and quality of life for people around the world. In the United States, construction is a multibillion dollar annual enterprise, employing nearly 10 million people. However, it appears that the fragmented nature of the industry continues to hamper productivity and hoped-for gains in efficiency. Issues involve an array of regulatory and legal constructs that: (1) redistribute risk; (2) present only low barriers to entry (making company startup somewhat easy); and (3) fail to provide the quality and quantity of labor necessary. These factors continue to produce overall inefficiencies throughout the construction industry, and ill prepare the industry for the formidable challenges of globalization, sustainability, population growth, and wise use of resources. The purpose of this paper is to review the past and present of construction engineering within the context of civil engineering, and to prescribe practical change to revitalize construction engineering education to meet future demands.     

Vision System for Tower Cranes

Operators of tower cranes enjoy a bird’s eye view of the site, which undeniably contributes to work safety and efficiency. Yet their work often involves blind lifts, as well as other viewing difficulties, that impede full utilization of the potential inherent in the operator’s location atop the crane. This paper reports on a tower-crane-mounted live video system that offers a solution for such difficulties, and consequently, enhances safety, improves productivity, and brings about direct and indirect cost savings. The development and implementation of the vision system are described as a successful academia–industry research and development joint effort. Work studies of numerous craning cycles resulted in considerable time savings, depending on the nature of the lift, lighting conditions, and viewing obstructions. In addition, a detailed list of benefits drawn on the basis of feedback received from the field is presented. The paper is aimed, first and foremost, at project managers as well as construction equipment and safety practitioners, who daily experience those situations that have prompted the development of the system. Researchers may benefit mainly from the lessons learned with respect to the role of academia–industry cooperation in the introduction of innovative systems in construction.     

Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides

Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical properties. Moreover, the ability of the phenylalanine amino acid or triphenylalanine to assemble into ordered nanostructures had been demonstrated. Herein, we explored the association potential of larger phenylalanine peptides, tetraphenylalanine, and pentaphenylalanine. A major challenge in studying the assembly of these peptides is their lack of solubility in different solvents. Yet, the remarkable capacity of acetic acid to solubilize FF was recently shown. Inspired by this, we examined whether this solvent could also be employed to dissolve these insoluble peptides. By utilizing the solvent-switch methodology, we revealed the self-assembly of tetraphenylalanine and pentaphenylalanine. The peptides were assembled into ordered autofluorescent elongated structures, which were further characterized by electron microscopy and spectroscopy analysis and could be utilized in future technological applications.     

AVPGEN-A test generator for architecture verification

This paper describes a system (AVPGEN) for generating tests (called architecture verification programs or AVP's) to check the conformance of processor designs to the specified architecture. To generate effective tests, AVPGEN uses novel concepts like symbolic execution and constraint solving, along with various biasing techniques. Unlike many earlier systems that make biased random choices, AVPGEN often chooses intermediate or final values and then solves for initial values that can lead to the desired values. A language called SIGL (symbolic instruction graph language) is provided in AVPGEN for the user to specify templates with symbolic constraints. The combination of user-specified constraints and the biasing functions is used to focus the tests on conditions that are interesting in that they are likely to activate various kinds of bugs. The system has been used successfully to debug many S/390 processors and is an integral part of the design process for these processors