Optofluidic concentration: plasmonic nanostructure as concentrator and sensor

The integration of fluidics and optics, as in flow-through nanohole arrays, has enabled increased transport of analytes to sensing surfaces. Limits of detection, however, are fundamentally limited by local analyte concentration. We employ the nanohole array geometry and the conducting nature of the film to actively concentrate analyte within the sensor. We achieve 180-fold enrichment of a dye, and 100-fold enrichment and simultaneous sensing of a protein in less than 1 min. The method presents opportunities for an order of magnitude increase in sensing speed and 2 orders of magnitude improvement in limit of detection.     

Growth of Cement Hydration Products on Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) were distributed on the surface of ordinary Portland cement (OPC) grains. The OPC/SWCNT composite was then hydrated at a 0.5 w/c ratio. The effects of the SWCNT on the early hydration process were studied using isothermal conduction calorimetry, high-resolution scanning electron microscopy and thermogravimetric analysis. The observed behavior of the composite samples was compared with both OPC sonicated without SWCNT and previously published data on as-delivered OPC. The SWCNT were found to accelerate the hydration reaction of the C₃S in the OPC. The morphology of both the initial C₃A and the C₃S hydration products were found to be affected by the presence of the SWCNT. In particular, the nanotubes appeared to act as nucleating sites for the C₃S hydration products, with the nanotubes becoming rapidly coated with C–S–H. The resulting structures remained on the surface of the cement grains while those in the sonicated and as-delivered OPC samples grew out from the grain surfaces to form typical C–S–H clusters. Classical evidence of reinforcing behavior, in the form of fiber pullout of the SWCNT bundles, was observed by 24 h of hydration.     

Gross Density and New Urbanism: Comparing Conventional and New Urbanist Suburbs in Markham,Ontario

This article compares the gross density of new suburban secondary plans with conventional suburban development in Markham, Ontario. The new plans accommodate 150,000 people and are North America's largest concentration of new communities planned with traditional neighbourhood design principles. The comparison demonstrates that the mean gross residential density of the New Urbanism areas (7.9 upa or 19.5 uph) is approximately 76% higher than that of the adjacent conventional suburban areas. The population density differential between New Urbanist and conventional suburban areas is approximately 66%. It appears that New Urbanism can accommodate high gross densities and consume less land in greenfield extensions of an urban growth boundary.     

High‐Performance Multifunctional Graphene‐PLGA Fibers: Toward Biomimetic and Conducting 3D Scaffolds

The development of electrically conducting fibers based on known cytocompatible materials is of interest to those engaged in tissue regeneration using electrical stimulation. Herein, it is demonstrated that with the aid of rheological insights, optimized formulations of graphene containing spinnable poly(lactic‐co‐glycolic acid) (PLGA) dopes can be made possible. This helps extend the general understanding of the mechanics involved in order to deliberately translate the intrinsic superior electrical and mechanical properties of solution‐processed graphene into the design process and practical fiber architectural engineering. The as‐produced fibers are found to exhibit excellent electrical conductivity and electrochemical performance, good mechanical properties, and cellular affinity. At the highest loading of graphene (24.3 wt%), the conductivity of as‐prepared fibers is as high as 150 S m^?1 (more than two orders of magnitude higher than the highest conductivity achieved for any type of nanocarbon‐PLGA composite fibers) reported previously. Moreover, the Young's modulus and tensile strength of the base fiber are enhanced 647‐ and 59‐folds, respectively, through addition of graphene.     

ZnFe2O4 Leaves Grown on TiO2 Trees Enhance Photoelectrochemical Water Splitting

TiO₂ has excellent electrochemical properties but limited solar photocatalytic performance in light of its large bandgap. One important class of visible‐wavelength sensitizers of TiO₂ is based on ZnFe₂O₄, which has shown fully a doubling in performance relative to pure TiO₂. Prior efforts on this important front have relied on presynthesized nanoparticles of ZnFe₂O₄ adsorbed on a TiO₂ support; however, these have not yet achieved the full potential of this system since they do not provide a consistently maximized area of the charge‐separating heterointerface per volume of sensitizing absorber. A novel atomic layer deposition (ALD)‐enhanced synthesis of sensitizing ZnFe₂O₄ leaves grown on the trunks of TiO₂ trees is reported. These new materials exhibit fully a threefold enhancement in photoelectrochemical performance in water splitting compared to pristine TiO₂ under visible illumination. The new materials synthesis strategy relies first on the selective growth of FeOOH nanosheets, 2D structures that shoot off from the sides of the TiO₂ trees; these templates are then converted to ZnFe₂O₄ with the aid of a novel ALD step, a strategy that preserves morphology while adding the Zn cation to achieve enhanced optical absorption and optimize the heterointerface band alignment.     

ATM for narrowband services

ATM is a broadband fast-packet technology, but its modern technological base should make it less expensive than existing circuit switching systems once economies of scale are reached. The article examines the use of ATM to address the growth of emerging narrowband services such as frame relay. ATM's flexibility in supporting variable rates and levels of service make it an ideal network technology to carry multiple services. While B-ISDN services promise many benefits to users, major issues must be addressed before such services can be available on a large scale. Utilizing ATM as a backbone technology to support the growing capacity needs of emerging narrowband services could facilitate more rapid introduction of ATM into the network infrastructure and speed delivery of future BISDN services     

利用FPGAIP核大幅缩短开发时间

在使用FPGA进行设计的最初十年,几乎没有任何设计会使用供应商或第三方提供的IP(知识产权)核。而如今,大约20%的FPGA设计都使用了IP核。今后五年,这个数据预计将会增加到50%。推动越来越多的设计使用IP的原因主要有两个:增加的设计需求以及IP产品的改进。     

Tailored solar optics for maximal optical tolerance and concentration

Recently identified fundamental classes of dual-mirror double-tailored nonimaging optics have the potential to satisfy the pragmatic exigencies of concentrator photovoltaics. Via a comprehensive survey of their parameter space, including raytrace verification, we identify champion high-concentration high-efficiency designs that offer unprecedented optical tolerance (i.e., sensitivity to off-axis orientation) - a pivotal figure-of-merit with a basic bound that depends on concentration, exit angle, and effective solar angular radius. For comparison, results for the best corresponding dual-mirror aplanatic concentrators are also presented.     

Risk evaluation for federally listed (roseate tern,piping plover) or candidate (red knot) bird species in offshore waters: A first step for managing the potential impacts of wind facility development on the Atlantic Outer Continental Shelf

With a worldwide increase in attention toward developing a reliance on renewable energy, there is a need to evaluate the effects of these facilities (solar, wind, hydropower) on ecosystems. We conduct a hazard and risk evaluation for three species of birds that are listed, or candidates for listing, as federally threatened or endangered in the US, and that might occur offshore on the Atlantic Outer Continental Shelf (AOCS) where wind power facilities could be developed. Our objectives were to: 1) provide conceptual models for exposure for each species, and 2) examine potential exposure and hazards of roseate tern (Sterna dougallii) and piping plover (Charadrius melodus, both federally endangered in the US) and red knot (Calidris canutus rufa, candidate species) in the AOCS. We used a weight-of-evidence approach to evaluate information from a review of technical literature. We developed conceptual models to examine the relative vulnerability of each species as a function of life stage and cycle (breeding, staging, migratory, wintering). These methods are useful for conducting environmental assessments when empirical data are insufficient for a full risk assessment. We determined that 1) Roseate terns are likely to be exposed to risk during the migratory and breeding season when they occur in the AOCS, as well as while staging. 2) Piping plovers are not likely to be at risk during the breeding season, but may be at risk during spring or fall migrations. Risk to this species is likely to be low from turbines located far from land as this species migrates mainly along the coast. 3) Red knots are potentially exposed to some risk during migration, especially long-distance migrants whose migratory routes take them over the AOCS. More information is required on exact spatio-temporal migration routes, flight altitudes (especially during ascent and descent), and behavioral avoidance of turbines by birds to ascertain their risk.