The Influence of Structural Defect on Mechanical Properties and Fracture Behaviors of Carbon Nanotubes

Due to the limitation of fabrication technologies nowadays, structural or atomistic defects are often perceived in carbon nanotubes (CNTs) during the manufacturing process. The main goal of the study aims at providing a systematic investigation of the effects of atomistic defects on the nanomechanical properties and fracture behaviors of single-walled CNTs (SWCNTs) using molecular dynamics (MD) simulation. Furthermore, the correlation between local stress distribution and fracture evolution is studied. Key parameters and factors under investigation include the number, type (namely the vacancy and Stone-Wales defects), location and distribution of defects. Results show that the nanomechanical properties of the CNTs, such as the elastic modulus, ultimate strength and ultimate strain, are greatly affected by the defects and also their percentage and type. It is also found that the CNTs present a brittle fracture as the strain attains a critical value, and in addition, the fracture crack tends to propagate along the high tensile stress concentration area. Moreover, the distribution pattern of defects is another driving factor affecting the nanomechanical properties of the CNTs and the associated fracture evolutions.     

Cytotoxicity and Immunological Response of Gold and Silver Nanoparticles of Different Sizes

The immunological response of macrophages to physically produced pure Au and Ag nanoparticles (NPs) (in three different sizes) is investigated in vitro. The treatment of either type of NP at ≥10 ppm dramatically decreases the population and increases the size of the macrophages. Both NPs enter the cells but only AuNPs (especially those with smaller diamter) up‐regulate the expressions of proinflammatory genes interlukin‐1 (IL‐1), interlukin‐6 (IL‐6), and tumor necrosis factor (TNF‐α). Transmission electron microscopy images show that AuNPs and AgNPs are both trapped in vesicles in the cytoplasma, but only AuNPs are organized into a circular pattern. It is speculated that part of the negatively charged AuNPs might adsorb serum protein and enter cells via the more complicated endocytotic pathway, which results in higher cytotoxicity and immunological response of AuNPs as compared to AgNPS.     

Simple monopoly price theory in a spatial market

One of main conclusions drawn by prior studies is that in a spatial market, the shape of the demand function can fully determine whether one simple pricing policy is superior to another either on the basis of the firm’s preference or social desirability while there is one assumption that is generally stipulated, namely, that the fixed market area assumption under which the market area is exogenously determined and remains the same under alternative pricing policies. In order to fully understand the impact of a demand function, this paper attempts to reexamine the relative economic advantages between two simple spatial pricing policies in a world with variable market area, that is, the market area is endogenously determined the price charged. We show that the fixed market area assumption is valid only where demand is linear, but no longer holds where demand is nonlinear. Moreover, and more importantly, we show that in a world with variable market area, some conclusions drawn by prior studies on the relative economic benefits of two pricing policies cannot remain valid. The main conclusion of this paper is that even the relative economic benefits of two simple spatial pricing policies is concerned, the impact of economic space is significant.

Effect of Hydrostatic Pressure on Aggregation and Viscoelastic Properties of Tilapia (Orechromis niloticus) Myosin

ABSTRACT: Hydrostatic pressures from 500 to 2000 atmospheres (atm) were applied at 0°C to determine the aggregation and viscoelastic properties of tilapia ( Orechromis niloticus ) myosin. Native myosins were present as long, linear, and single filaments. After a 500-atm treatment, these filaments unfolded and their volume decreased. Upon 1000-atm and 1500-atm treatments, myosins aggregated and formed inseparable network structures. Further, they transformed from viscous sol to elastic gels with a pressure of 500 to 1000 atm. At 2000 atm, the myosin formed irregular aggregates. This study reveals that at 500 atm, myosins unfolded; at 1000 atm, they aggregated, and beyond 1500 atm, they formed both a precipitate and gel.     

Comprehensive study on a novel bidirectional tunnelingprogram/erase NOR-type (BiNOR) 3-D flash memory cell

In this paper a recently proposed bidirectional tunneling program/erase (P/E) NOR-type (BiNOR) flash memory is extensively investigated. With the designated localized p-well structure, uniform Fowler-Nordheim (FN) tunneling is first fulfilled for both program and erase operations in NOR-type array architecture to facilitate low power applications. The BiNOR flash memory guarantees excellent tunnel oxide reliability and is provided with fast random access capability. Furthermore, a three-dimensional (3D) current path in addition to the conventional two-dimensional (2D) conduction is proven to improve the read performance. The BiNOR flash memory is thus promising for low-power, high-speed, and high-reliability nonvolatile memory applications     

Performance evaluation of random power capture on mobile communications

Power assignment schemes are man‐made methods to enhance the capture effect of radio communications. In a previous study, Wen and Yang investigated the combined capture effect of the fixed power assignment scheme, Rayleigh fading, and near–far effect on the performance of packet radios. The performance analysis was limited to an infinite population environment. This assumption is reasonable for a conventional packet radio system with a vast service area. However, for a cellular mobile system, a finite population model should be used. In this paper, we analyse the combined natural and man‐made capture effect on the performance of a cellular system with finite population in each cell. A random power assignment scheme is adopted to produce the man‐made capture. The system throughput and delay are carried out by a Markov model. Some numerical calculations are used to demonstrate the degree of performance improvement. Copyright © 2001 John Wiley & Sons, Ltd.     

Structural design of current-mode biquad filters

This work describes how to generate and design a novel current-mode biquad filter model using tunable multiple-output operational transconductance amplifiers and grounded capacitors (MO-OTA-Cs) for synthesizing both transmission poles and zeros. Transfer functions of low-pass, band-pass, high-pass, notch and all-pass are realized based on the filter model. The theory focuses mainly on establishing a relationship between the cascaded MO-OTA-Cs and the multiple-loop feedback matrix, which makes the structural generation and design formulas. All the filter architectures contain only grounded capacitors, which can absorb parasitic capacitances and require smaller chip areas than floating ones. The simulation results are also presented to confirm the theoretical analysis.     

Bimorph actuator with monolithically integrated CMOS OFET control

We present an electrostrictive polymer bimorph controllable with low voltage through an integrated CMOS OFET control system. We have actuated the device by applying voltages up to 400 V to the control system, and can actuate the control with 60 V switching. The electrostrictor material was used both as the substrate for the transistors and as the dielectric layer for the control circuitry. This allows for a reduction in the number of layers in the structure, minimizing the clamping effect that would compromise the strain capabilities of the device. We have characterized the macroscopic displacement of the structure through a radius of curvature measurement, ranging from 11.4 mm to 7.5 mm depending on the supply voltage provided. The architecture proposed can be scaled to larger system with higher supply voltages.     

粹化自然——关于休憩亭的二三事

项目所在的城市昆山位于苏州与上海之间,有着千年的历史文化沉淀,境内的周庄、镜溪等古镇是典型的江南水乡.近些年,昆山经济的迅猛发展、新旧文化的交织更替与人们日益增高的生活需求,都激烈地冲击着原有的城市格局和地理风貌.昆山市区沿河处大多已开发为提供市民活动的滨河公园,间或穿插着小尺度的商业空间.在此背景下,位于滨河公园内的本项目除了要提供未来可供出租的商业空间外,也需满足作为公园基本配套设施的公厕和休憩等功能需求.