Structure–Property Relationships in Aligned Electrospun Barium Titanate Nanofibers

Barium titanate nanofibers were uniaxially aligned by electrospinning onto a rotating copper wire drum and alignment was maintained during calcination of the fibers. Two methods for maintaining alignment during calcination were tested, by either using carbon tape or a peeling off method to remove the aligned fibers from the mandrel followed by calcination. The carbon tape removal method led to the formation of shorter aligned nanowires while the peeling off method resulted in longer nanofibers. Additionally, the effects of calcination temperature and time on crystal structure were also examined. The degree of tetragonality in the barium titanate nanofibers increased at higher calcination temperatures and times. Piezoelectricity was confirmed in the nanofibers calcined using piezoeresponse force microscopy, yielding a d₃₃ value of 15.5 pm/V. Using the methods presented here, large quantities of aligned piezoelectric barium titanate and other ceramic fibers or wires can be produced to fulfill their demand in novel microelectronics.     

Preparation of Pt/C cathode catalyst supported on chestnut-like mesoporous carbon for fuel cell applications

Fuel cells have received worldwide attention as a next-generation renewable energy technology. However, catalyst cost and durability are the main issue hampering the commercialization of fuel cells. Many studies have focused on the physicochemical properties of the carbon support to improve the catalyst’s properties. Mesoporous carbons are suitable candidates because of their appropriate structural characteristics, including high surface area, large pore size, and regularly interconnected mesopores that permit efficient diffusion of the reactants and by-products. In this study, supports made from chestnut-like carbon consisting of platelet carbon nanofibers were fabricated by selective catalytic gasification of activated carbon. Pt/C catalysts were synthesized from these support structures using the impregnation method. Catalyst performance and characteristics were investigated by N₂ adsorption/desorption isotherms, X-ray diffractions, and the rotating disk electrode technique for the oxygen reduction reaction.     

DNA Antenna Tile‐Associated Deoxyribozyme Sensor with Improved Sensitivity

Some natural enzymes increase the rate of diffusion‐limited reactions by facilitating substrate flow to their active sites. Inspired by this natural phenomenon, we developed a strategy for efficient substrate delivery to a deoxyribozyme (DZ) catalytic sensor. This resulted in a three‐ to fourfold increase in sensitivity and up to a ninefold improvement in the detection limit. The reported strategy can be used to enhance catalytic efficiency of diffusion‐limited enzymes and to improve sensitivity of enzyme‐based biosensors.     

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.     

What matters the most for economic development? Evidence from the Community Development Financial Institutions Fund

Governments use incentive programmes to attract new businesses. Due to limited resources, there are questions about which incentives are most effective. Using establishment data from California, and data on the location of disbursements through two federal programmes, we consider the effectiveness of different programmes in attracting new businesses. We find that the amount of funding through the New Markets Tax Credit programme has a significant impact on business activity but find no evidence of an effect from the Community Development Financial Institutions programme. Our results suggest that the effectiveness of these programmes depends on how they provide assistance.     

Characteristics and 3D formation of PVA and PEO electrospun nanofibers with embedded urea

The behavior of electrospun polyvinyl alcohol (PVA) and polyethylene oxide (PEO) nanofibers embedded with urea is studied as a function of various process parameters. Our results show that three‐dimensional nanofiber networks can be obtained when high concentrations of urea in the solution are used during electrospinning. The nanofibers are characterized using both scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The stability of the nanofiber as a function of electric field has also been studied. The successful formation of three‐dimensional nanofiber networks can open new trends toward applications in fertilizers containing nanofibers in the nanoagricultural field. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39840.     

Detailed Microphysical Modeling of the Formation of Organic and Sulfuric Acid Coatings on Aircraft Emitted Soot Particles in the Near Field

The development of a detailed microphysical model that describes the complex multicomponent interactions between organic vapors and soot particles emitted from aircraft gas turbine engines is presented. Our model formulation includes both soot surface activation by organic vapors and organic vapor condensation on the activated part of the soot surfaces. To enable this formulation, approaches to estimate chemical and physical properties of aerosols containing complex mixtures of sulfuric acid, water, and organic molecules were developed. Relevant distributions of a list of organic surrogates at the engine exit plane were used to represent complex organic emissions from aircraft engines. A parametric study was performed using this new formulation to understand the effects of ambient conditions, organic emissions levels, and mass accommodation coefficient values on the evolution of near field volatile particulate matter emissions from aircraft engines at ground level.

Copyright 2014 American Association for Aerosol Research