正确理解微控制器的关键结构特性可以改善设计

分布通道用户在设计诸如无线网络应用等高性能、低成本和低功耗系统时，需要既能减少系统器件成本又适合其产品要求的集成微控制器。这些应用要求运行速度大于33MHz，既有片上RAM和Flash存储器，又有易于使用高级语言编程的先进外围设备阵列。     

Effect of mixed solvents on PCDTBT:PC70BM based solar cells

We investigated the effect of solvents on the morphology, charge transport and device performance of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC₇₀BM) based solar cells. To carry out this investigation, chloroform and 1,2-dichlorobenzene were chosen as good solvents of the two compounds. Films prepared with chloroform exhibit larger domains than those prepared with 1,2-dichlorobenzene and their size increases with the amount of PC₇₀BM. Fine tuning of the domain size was realized by using a solvent of mixed chloroform and 1,2-dichlorobenzene. At a mixing ratio of 50%:50%, a power conversion efficiency of 6.1% was achieved on PCDTBT:PC₇₀BM (1:3) devices with an active area of 1 cm², under air mass 1.5 global (AM 1.5 G) irradiation at 100 mW/cm².     

Managing the Public Sphere: Journalistic Construction of the Great Globalization Debate

There is little consensus on what constitutes open, deliberative media discourse. We offer a simple, measurable, and comparative model based on 3 aspects of source and issue construction in news accounts: access, recognition, and responsiveness. The model is applied to coverage of 2001–2003 World Economic Forum (WEF) meetings and protests against the organization's role in global economic policies. Both demonstrators and WEF participants were granted news access, but WEF actors were recognized more formally and given greater input in news content, including ownership claims to many activist issue positions. Journalistic deference to the WEF communication agenda limited mutual responsiveness. The journalistic process systematically managed the debate about globalization on terms that favored elites over citizen-activists.     

Experimental Study of Capture Effect for Medium Access Control with ALOHA

In this paper, we investigate the capture effect through experiments conducted with Iris nodes equipped with AT86RF230 radio transceivers. It is shown that the first arriving packet in a collision can capture the radio channel for equal power transmissions and may be decoded depending on the amount of overlap. A new 3‐packet‐capture scenario is introduced and implemented. To be able to understand the impact of capture on the throughput performance of wireless sensor networks, we present an analysis of the capture coefficient using our practical results. For real‐world implementations, the throughput of pure ALOHA considering a finite number of users is presented in analytical form. The capture coefficient is then applied to pure ALOHA as a case study. Using analytical and practical implementations of the capture effect on ALOHA, a very good match in channel throughput performance enhancement is demonstrated over the non‐capture effect case. TinyOS‐2.x is used to program the nodes and to observe data exchange on a computer through a base station.     

Inkjet printed metallizations for Cu(In1−x Ga x )Se2 photovoltaic cells

This study reports the inkjet printing of Ag front contacts on Aluminum doped Zinc Oxide (AZO)/intrinsic Zinc Oxide (i‐ZnO)/CdS/Cu(In_1−xGa_x)Se₂ (CIGS)/Mo thin film photovoltaic cells. The printed Ag contacts are being developed to replace the currently employed evaporated Ni/Al bi‐layer contacts. Inkjet deposition conditions were optimized to reduce line resistivity and reduce contact resistance to the Al:ZnO layer. Ag lines printed at a substrate temperature of 200°C showed a line resistivity of 2.06 µΩ · cm and a contact resistance to Al:ZnO of 8.2 ± 0.2 mΩ · cm² compared to 6.93 ± 0.3 mΩ · cm² for thermally evaporated contacts. These deposition conditions were used to deposit front contacts onto high quality CIGS thin film photovoltaic cells. The heating required to print the Ag contacts caused the performance to degrade compared to similar devices with evaporated Ni/Al contacts that were not heated. Devices with inkjet printed contacts showed 11.4% conversion efficiency compared to 14.8% with evaporated contacts. Strategies to minimize heating, which is detrimental for efficiency, during inkjet printing are proposed. Copyright © 2011 John Wiley & Sons, Ltd.     

Hierarchical Nanowire Arrays Based on ZnO Core−Layered Double Hydroxide Shell for Largely Enhanced Photoelectrochemical Water Splitting

Well‐aligned hierarchical nanoarrays containing ZnO core and layered double hydroxide (LDH) nanoplatelets shell have been synthesized via a facile electrosynthesis method. The resulting ZnO@CoNi–LDH core?shell nanoarray exhibits promising behavior in photoelectrochemical water splitting, giving rise to a largely enhanced photocurrent density as well as stability; much superior to those of ZnO‐based photoelectrodes. This is attributed to the successful integration of photogenerated electron–hole separation originating from the ZnO core and the excellent electrocatalytic activity of LDH shell. This work provides a facile and cost‐effective strategy for the fabrication of multifunctional nanoarrays with a hierarchical structure, which can be potentially used in energy storage and conversion devices.     

Cell‐Tethered Ligands Modulate Bone Remodeling by Osteoblasts and Osteoclasts

The goals of the present study are to establish an in vitro co‐culture model of osteoblast and osteoclast function and to quantify the resulting bone remodeling. The bone is tissue engineered using well‐defined silk protein biomaterials in 2D and 3D formats in combination with human cells. Parathyroid hormone (PTH) and glucose‐dependent insulinotropic peptide (GIP) are selected because of their roles in bone remodeling for expression in tethered format on human mesenchymal stem cells (hMSCs). The cell‐modified biomaterial surfaces are reconstructed from scanning electron microscopy images into 3D models for quantitative measurement of surface characteristics. Increased calcium deposition and surface roughness are found in 3D surface models of silk protein films remodeled by co‐cultures containing tethered PTH, and decreased surface roughness is found for the films remodeled by tethered GIP co‐cultures. Increased surface roughness is not found in monocultures of hMSCs expressing tethered PTH, suggesting that osteoclast‐osteoblast interactions in the presence of PTH signaling are responsible for the increased mineralization. These data point towards the design of in vitro bone models in which osteoblast‐osteoclast interactions are mimicked for a better understanding of bone remodeling.     

Hierarchical NiMn Layered Double Hydroxide/Carbon Nanotubes Architecture with Superb Energy Density for Flexible Supercapacitors

A hierarchical nanostructure composed of NiMn‐layered double hydroxide (NiMn‐LDH) microcrystals grafted on carbon nanotube (CNT) backbone is constructed by an in situ growth route, which exhibits superior supercapacitive performance. The resulting composite material (NiMn‐LDH/CNT) displays a three‐dimensional architecture with tunable Ni/Mn ratio, well‐defined core‐shell configuration, and enlarged surface area. An electrochemical investigation shows that the Ni₃Mn₁‐LDH/CNT electrode is rather active, which delivers a maximum specific capacitance of 2960 F g^–1 (at 1.5 A g^–1), excellent rate capability (79.5% retention at 30 A g^–1), and cyclic stability. Moreover, an all‐solid‐state asymmetric supercapacitor (SC) with good flexibility is fabricated by using the NiMn‐LDH/CNT film and reduced graphene oxide (RGO)/CNT film as the positive and negative electrode, respectively, exhibiting a wide cell voltage of 1.7 V and largely enhanced energy density up to 88.3 Wh kg^–1 (based on the total weight of the device). By virtue of the high‐capacity of pseudocapacitive hydroxides and desirable conductivity of carbon‐based materials, the monolithic design demonstrated in this work provides a promising approach for the development of flexible energy storage systems.     

Composite Living Fibers for Creating Tissue Constructs Using Textile Techniques

The fabrication of cell‐laden structures with anisotropic mechanical properties while having a precise control over the distribution of different cell types within the constructs is important for many tissue engineering applications. Automated textile technologies for making fabrics allow simultaneous control over the color pattern and directional mechanical properties. The use of textile techniques in tissue engineering, however, demands the presence of cell‐laden fibers that can withstand the mechanical stresses during the assembly process. Here, the concept of composite living fibers (CLFs) in which a core of load bearing synthetic polymer is coated by a hydrogel layer containing cells or microparticles is introduced. The core thread is drawn sequentially through reservoirs containing a cell‐laden prepolymer and a crosslinking reagent. The thickness of the hydrogel layer increases linearly with to the drawing speed and the prepolymer viscosity. CLFs are fabricated and assembled using regular textile processes including weaving, knitting, braiding, winding, and embroidering, to form cell‐laden structures. Cellular viability and metabolic activity are preserved during CLF fabrication and assembly, demonstrating the feasibility of using these processes for engineering functional 3D tissue constructs.     

Synergistic Computational‐Experimental Approach to Improve Ionene Polymer‐Based Functional Hydrogels

The manifold applications of ionene‐based materials such as hydrogels in daily life, biomedical sciences, and industrial processes are a consequence of their unique physical and chemical properties, which are governed by a judicious balance between multiple non‐covalent interactions. However, one of the most critical aspects identified for a broader use of different polyelectrolytes is the need of raising their gelation efficiency. This work focuses on surfactant‐free ionene polymers 1 ? 3 containing DABCO and N,N′‐(x‐phenylene)dibenzamide (x = ortho‐/meta‐/para‐) linkages as model systems to develop a combined computational‐experimental approach to improve the hydrogelation through a better understanding of the gelation mechanism. Molecular dynamics simulations of isomeric ionenes 1–3 with explicit water molecules point out remarkable differences in the assembly of the polymeric chains in each case. Interchain regions with high degree of hydration (i.e., polymer···water interactions) and zones dominated by polymer···polymer interactions are evident in the case of ortho‐ ( 1 ) and meta‐ ( 2 ) isomeric ionenes, whereas domains controlled by polymer···polymer interactions are practically inexistent in 3 . In excellent agreement, ortho‐ionene 1 provides experimentally the best hydrogels with unique features such as thixotropic behavior and dispersion ability for single‐walles carbon nanotubes.