Isolation of Ambient Particles of Known Critical Supersaturation: The Differential Activation Separator (DAS)

A field-deployable instrument has been developed that isolates from an ambient aerosol those particles that have critical supersaturations, S_c, within a narrow, user-specified, range. This Differential Activation Separator (DAS) consists of two continuous flow diffusion chambers housed within a single enclosure. Particles are introduced into the upstream chamber referred to as the CCN remover (CCNR) near the centerline between a warm, water-soaked, plate and a cool, continuously circulated, water bath. Those particles that activate at the resulting peak supersaturation, S_p, grow quickly and fall into the water bath. The remaining aerosol enters the second chamber referred to as the CCN separator (CCNS), which differs from the CCNR primarily in the use of a salt solution in the lower bath. The imposed temperature differential establishes an S_p slightly higher than that maintained in the upstream chamber, while the presence of a salt solution at the lower boundary results in a subsaturated region in roughly the lower half of the chamber. Those particles having (S_p)_CCNR < S _c < (S_p)_CCNS activate in this chamber and begin to fall due to gravitational settling. Before reaching the lower bath, the droplets evaporate in the subsaturated environment and continue to travel towards the chamber exit. The previously activated particles in the lower half of the chamber and the unactivated particles in the upper half are extracted in separate flows that are subsequently dried. Calibration of the DAS was achieved by measuring the size distribution of separated particles when a polydisperse ammonium sulfate aerosol was introduced.     

Nanopore-Based Analysis of Chemically Modified DNA and Nucleic Acid Drug Targets

Nucleic acids are central figures in many of life’s key molecular processes, e.g., enzymatic activity, epigenetics/gene regulation, viral replication, aging, cancer, and other diseases. Over the past two decades, nanopores have emerged as a new tool for studying the properties of nucleic acids at the single-molecule level. In this review, we summarize the use of nanopores as sensors of nucleic acid structure, particularly for studying chemically modified and damaged DNA, and for probing the interactions of small-molecule drugs with nucleic acid targets.     

The Role of α1-Adrenoceptor Antagonists in the Treatment of Prostate and Other Cancers

This review evaluates the role of α-adrenoceptor antagonists as a potential treatment of prostate cancer (PCa). Cochrane, Google Scholar and Pubmed were accessed to retrieve sixty-two articles for analysis. In vitro studies demonstrate that doxazosin, prazosin and terazosin (quinazoline α-antagonists) induce apoptosis, decrease cell growth, and proliferation in PC-3, LNCaP and DU-145 cell lines. Similarly, the piperazine based naftopidil induced cell cycle arrest and death in LNCaP-E9 cell lines. In contrast, sulphonamide based tamsulosin did not exhibit these effects. In vivo data was consistent with in vitro findings as the quinazoline based α-antagonists prevented angiogenesis and decreased tumour mass in mice models of PCa. Mechanistically the cytotoxic and antitumor effects of the α-antagonists appear largely independent of α 1-blockade. The proposed targets include: VEGF, EGFR, HER2/Neu, caspase 8/3, topoisomerase 1 and other mitochondrial apoptotic inducing factors. These cytotoxic effects could not be evaluated in human studies as prospective trial data is lacking. However, retrospective studies show a decreased incidence of PCa in males exposed to α-antagonists. As human data evaluating the use of α-antagonists as treatments are lacking; well designed, prospective clinical trials are needed to conclusively demonstrate the anticancer properties of quinazoline based α-antagonists in PCa and other cancers.     

The role of surface oxygen on copper metal in catalysts for the synthesis of methanol

Discrepancies in experimental measurements of adsorbed oxygen coverage on copper metal surfaces in working Cu/ZnO/Al₂O₃ catalysts are interpreted in terms of two types of adsorbed oxygen. The first, O(a), is identical with that observed in studies of single‐crystal copper surfaces. The second, O^*(a), not seen in single‐crystal studies, is more strongly bonded to the metal surface. It is suggested that the adsorption sites of O^*(a) contain Zn as well as Cu, from surface α‐brass (copper/zinc alloy) formation during catalyst reduction. Earlier experimental results on O(a) coverages on various supported copper catalysts are re‐assessed. Only catalysts containing Zn (or Ga) gave abnormally high coverages: with other supports, basic or acidic, O(a) coverages are less than ∼0.1. This revised version was published online in July 2006 with corrections to the Cover Date.     

Microcomputers Implementation of Digital Control Strategies for Structural Response Reduction

Abstract: In the past, implementation of active structural control strategies employing PC-based hardware has often been problematic, and there seems to be a need to improve the understanding of the issues associated with implementation of digital control, as well as to reduce the excessive computational times required for I/O processes and calculation of control forces. Recently developed hardware based on dedicated digital signal processing (DSP) chips has offered new possibilities for control algorithm implementation. This paper discusses digital control system concepts and specific practical aspects of digital control implementation, including the use of supervision. Details regarding active structural control using the Texas Instruments TMS32OC30 DSP chip and experimental verification of the hardware performance are given.     

Tests of the dynamic field theory and the spatial precision hypothesis: Capturing a qualitative developmental transition in spatial working memory.

This study tested a dynamic field theory (DFT) of spatial working memory and an associated spatial precision hypothesis (SPH). Between 3 and 6 years of age, there is a qualitative shift in how children use reference axes to remember locations: 3-year-olds’ spatial recall responses are biased toward reference axes after short memory delays, whereas 6-year-olds’ responses are biased away from reference axes. According to the DFT and the SPH, quantitative improvements over development in the precision of excitatory and inhibitory working memory processes lead to this qualitative shift. Simulations of the DFT in Experiment 1 predict that improvements in precision should cause the spatial range of targets attracted toward a reference axis to narrow gradually over development, with repulsion emerging and gradually increasing until responses to most targets show biases away from the axis. Results from Experiment 2 with 3- to 5-year-olds support these predictions. Simulations of the DFT in Experiment 3 quantitatively fit the empirical results and offer insights into the neural processes underlying this developmental change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fatty acid composition as a basis for identification of commercial fats and oils

Gas liquid chromatographic analyses of 200 samples of commercial fats and oils were compared to the standard ranges specified by the Food and Agriculture Organization/World Health Organization Codex Alimentarius Committee on Fats and Oils at its seventh session, London, England, March 25, 1974. Only six samples fell notably outside the standard ranges. On the basis of this information, the U.S. delegation is offering for consideration by the Committee at its next meeting a method for using the fatty acid composition of a fat or oil to determine its authenticity.     

Optimization of Structures Subject to Stochastic Dynamic Loading

Structural optimization has progressed substantially over the last half century. However, the literature on optimization of structures under random excitation is limited. This study provides a framework for structural optimization subject to stochastic dynamic loading. Illustrative examples of structures under nonstationary seismic and stationary wind loads are presented to demonstrate the procedure. Both safety and serviceability are considered concurrently. The objective function for safety is given in terms of both harmful interstory drift and harmful interstory drift angle; whereas for serviceability, the objective function is defined in terms of floor acceleration. Safety and serviceability are shown to be competing objectives under both seismic and wind excitation; however, the contrast is less under wind excitation. The proposed optimization framework provides a rational manner in which engineering design tradeoffs can be made between the two competing objectives.     

Axial Strain Accelerations Approach for Damage Localization in Statically Determinate Truss Structures

This work proposes an efficient and reliable method for damage localization in truss structures. The damage is localized on the basis of measured acceleration signals of the structure followed by simple statistical signal processing. It has three main advantages over many existing methods. First, it can be directly applied to real engineering structures without the need of identifying modal parameters or solving any global optimization problem. Second, the proposed method has higher sensitivity to damage than some other frequently used methods and allows to localize damage as small as a few percentages. Third, it is a model‐free method, which does not require precise finite element model development or updating. Validation of the method has been conducted on numerical examples and laboratory‐scale trusses. Two types of frequently used trusses have been selected for this study, namely, Howe and Bailey trusses. The presented experimental validation of the method shows its efficiency and robustness for damage localization in truss structures.