bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of pyrolytic monolithic carbon composites for the conditioning of spent ion exchange resins
Authors: Ramos Pamela B. , Fuentes Néstor O. , Luca Vittorio
Published: November 2012

The pyrolysis of ion exchange resin beads that are used for the purification of water in reactor primary- and secondary-cooling circuits can result in stable and leach resistant carbonaceous products. However, free flowing beads are less desirable waste forms for disposal in sub-surface or surface repositories than monolithic masses of low porosity. We have investigated the pyrolysis of polymeric resin – cation exchange resin composites to give mechanically robust and chemically durable monolithic carbonaceous waste forms that are suitable for repository disposition. Also investigated was the dependence of product properties on various processing parameters (temperature ramp and final temperature). As a first approach, epoxy resins were used for the preparation of monoliths since such resins cure at room temperature and result in a relatively high carbon yield. Carbonaceous monolithic products were prepared at 400, 500, 600, 700 and 800 °C using a temperature ramp of 2°C/min. The products were maintained at the chosen temperatures for a period of one hour. Mass losses, volume reduction, hardness and compressive strength were measured and mathematical functions are proposed to describe the measured values of these properties. The carbon monoliths were observed to be mechanically robust.
“Polymer Solar Modules: Laser Structuring and Quality Control by Lock-In Thermography”
Authors: Bärenklau Maik , Muhsin Burhan , Moreno Javier Gonzalez , Rösch Roland , Horn Alexander , Gobsch Gerhard , Stute Uwe , Hoppe Harald
Published: November 2012

Polymer solar modules, based on glass or flexible PET-substrates, structured either by laser ablation, mechanical scribing, or by a combination of the two, were prepared and analyzed. The photo-active layer of the solar modules is based on poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester or Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:phenyl-C71-butyric acid methyl ester donor-acceptor bulk heterojunctions. Since such polymer-fullerene solar cells and modules are designed in a multilayer architecture, local defects such as shunts or blocking junctions in the device can cause critical losses to the solar module performance. Of special importance for solar module preparation is the structuring process, as it allows the serial interconnection of the cells. The high precision required for removing neither too few nor too much of the thin layers to be structured presents challenges in the processing of polymer solar modules. Herein we demonstrate that laser structuring is a suitable technology to face these challenges. We report about completely or partially laser structured polymer photovoltaic modules. By using highly sensitive dark lock-in thermography we analyze the influence of defects and failures on the performance and operation of solar module devices. Finally, promising results for fully laser structured solar modules on glass and partly laser structured solar modules on PET are presented.
Extended Exciton Diffusion in Rubrene Single-Crystalline Organic Solar Cells
Authors: Miyadera Tetsuhiko , Ohashi Noboru , Taima Tetsuya , Yamanari Toshihiro , Yoshida Yuji
Published: November 2012

Single-crystalline organic solar cells were investigated. Rubrene single crystals made by train sublimation method were used for the active layer of the solar cells. Typical solar cell characteristics and external quantum efficiency (EQE) were observed with the film thickness of several micrometers. In spite of their large film thickness, the EQE spectra showed no screening effect, which means that absorbed photons efficiently converted to electric charges. This can be attributed to the extended exciton diffusion due to uniform and trap free characteristic of rubrene single crystal.
Near Infrared Tunable Gold Nanoparticles for Low Power Laser Ablation of Esophageal Adenocarcinoma
Authors: Zhang Guandong , Jasinski Jacek , Patel Dhruvinkumar , James Kurtis , Sun Xinghua , Gobin Andre M.
Published: November 2012

Gold nanoparticles (GNPs) with precisely controlled near infrared (NIR) absorption were synthesized by one-step reaction of chloroauric acid and sodium thiosulfate. The NIR absorption wavelengths and average particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. The as-synthesized GNPs consist of different shape and size, including small spherical gold colloids and larger non-spherical gold crystals. The GNPs with good chemical and optical stability only form in a suitable range of the HAuCl4/Na2S2O3 molar ratio. High molar ratio of HAuCl4/Na2S2O3 reduces GNPs stability due to Ostwald ripening. Chitosan coating improves particle stability and allows these GNPs effective ablation for esophageal adenocarcinoma under low power NIR laser radiation.
Rapid Diagnosis of E. Coli using Carbon Nanotube Field Effect Transistor Direct Binding Assay
Authors: Park Woo Jae , Chung Sung-Jae , Kim Man S. , Stefansson Steingrimur , Ahn Saeyoung
Published: November 2012

Enzyme-Linked Immuno-Sorbent Assay (ELISA), and other methods based on the same principle, are sensitive and specific, but they suffer from several disadvantages, such as their inherent complexity and requirement for multiple reagents, incubation and washing steps and require a relatively large sample size. We have adapted a new carbon nanotube field effect transistors (CNT-FET) based platform to capture Escherichia coli antigens using only the capture anti-body showing good correlation with an established ELISA assay contrived positive and negative specimens were used to test the new CNT-FET platform and results were obtained within three minutes per each sample. The test is easy to perform, rapid, and cost efficient making it a valuable screening tool for E. coli. In this study, we looked at the applicability of using CNT field effect transistor based biosensor as a rapid diagnostic platform for Escherichia coli O157:H7. The CNT-FETs platform detected positive E. coli samples in three minutes using only 2.5 μL of sample volume. This low sample volume required by the CNT-FET platform can be especially advantageous for diagnostic tests constricted by limited amount of samples.
Photonic Crystals on Erbium doped tellurite Thin Films for Broadband Enhanced Photoluminescence at Near Infrared
Authors: Lin Pao T. , Vanhoutte M. , Hu J. , Patel N. S. , Singh V. , Cai Y. , Camacho R. , Michel J. , Kimerling L. C. , Agarwal A. , Dimas Clara
Published: November 2012

Two dimensional Er3+-TeO2 thin film photonics crystals (PhCs) are fabricated. These PhCs demonstrate broadband enhancement of PL emission at near Infrared (NIR). The PhC structures are written by dual beam focused ion beam (FIB). Highly uniformed patterns with smooth surfaces are observed. A pattern resolution better than hundred nanometers is achieved. PhCs arrays with photonic lattice constants from 350 nm to 1700 nm are examined in order to optimize the PL extraction efficiency. Strong photoluminescence around 1530 nm is observed by 488-532 nm lasers pumping. A confocal microscopy with spectrometer is used to capture the broadband PL signals from individual PhC array.

The emission enhancement factor and spectral dependent extraction ratio are analyzed to find the interaction between PL lightwave and PhC structures. By optimize the PhC structures, 1500 um-1560 um broadband PL is successfully converted between the PL emission layer and the external cavity. A 60 % enhancement of surface extraction efficiency is achieved when PhC with periodicity a=800 nm is applied. When photonic lattice constants a are smaller than the critical periodicity 600 nm, the PL light becomes confined inside the thin film layer. Simulation is also performed by two dimensional finite difference time domain (FDTD) calculation in order to explain the experimental observed anisotropic PL enhancements.

The broadband PL enhancement enables Er3+-TeO2 PhCs thin film as a potential light source for three dimensional integrated photonic circuits.
Biomimetic Hemo-compatible Surfaces of Polyurethane by Grafting Copolymer Brushes of Poly(ethylene glycol) and Poly(phosphorylcholine methacrylate)
Authors: Yang Dazhi , Feng Yakai , Behl Marc , Lendlein Andreas , Zhao Haiyang , Khan Musammir , Guo Jintang
Published: November 2012

Polyurethanes (PU) have been widely used as biomaterial in recent years, while thrombus may still occur when contacting with blood especially for extended period of time. Poly(ethylene glycol) (PEG) and phosphorylcholine (PC)-based polymers are commonly employed for surface modification to create protein repellent surfaces. PC-based polymers have been investigated as biomimetic materials because PC is the major component in the outer layer of cell membranes. In this study, the biomimetic copolymer brush of PEG-b-poly(2-methacryloyloxyethyl phosphorylcholine) on PU surfaces was synthesized via atom transfer radical polymerization (ATRP) with a surface initiator. The flexible PEG chain was 200 g·mol-1, while the poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) chain length was controlled by the ratio of monomer to sacrificial initiator in solution. The topology of the modified surfaces was characterized by the phase image of atomic force microscopy (AFM) to study the synergy effect between PEG chains and poly(MPC) chains. The unmodified and modified surfaces were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle and platelet adhesion. The results demonstrated that efficient grafting of PEG-b-poly(MPC) brushes on the surfaces was achieved. The PU surfaces modified with PEG and phosphorylcholine zwitterionic brushes showed effective resistance to platelet adhesion and high hemocompatibility in vitro. These PEG and PC-grafted PU materials might be potentially applied in blood-contacting materials or devices due to their good mechanical and hemocompatible properties.
Nanotube-Enhanced Aerosol-Jet Printed Electronics for Embedded Sensing of Composite Structural Health
Authors: Zhao Da , Liu Tao , Zhang Mei , Chen Jen-Ming , Wang Ben
Published: November 2012

Innovative printing technology enables fine feature deposition (below 10μm) of electronic materials onto low-temperature, non-planar substrates without masks. This could be a promising technology to meet the requirements of present and future microelectronic systems. Silver nanoparticles (NP) ink is widely used for printed electronics; however, its electrical conductivity is low compared to bulk materials. In order to improve the electrical conductivity of printed tracks for the aerosol printing technique, we developed a novel carbon nanotubes (CNTs)/silver NP ink by mechanical stirring and sonication. The produced sample inks with different concentration of CNTs that were printed with Aerosol Jet® printing system. We found that the CNTs bridged the defects in some printed silver lines, thereby lowering the electrical resistivity by 38%. However, no further improvements were observed with a higher CNT concentration in the silver NP ink samples. We hypothesize that CNT bridges connects the defects thus decreasing the resistivity of printed silver lines when CNT concentration is under the percolation level. However, when it is above a concentration threshold, the resistivity of printed silver lines stops decreasing and even increases because of Schottky barrier effect.
Development of Objective Type Atomic Force Microsocopy for PSISCM-Nanoindentation Combined System.
Authors: Fujitsuka M. , Yamaguchi M. , Ueno S.
Published: November 2012

Nanoindentation test is known as instrumented indentation test (IIT) in the nano range for hardness and material parameters (ISO14577). It is a simple and effective method for evaluating the mechanical properties such as elasticity/stiffness, hardness and adhesion. Generally IIT is the method that doesn’t have to observe the residual impression. However, it is necessary to observe the residual impression and surface of test piece to obtain the material behavior such as pile-up/sink-in, crack. In past work, the phase shifting interferometric scanning confocal microscope (PSISCM)-nanoindenataion combined system was developed to obtain the tilt of surface and the geometrical shape of residual impression that are deeper than one micron. This system is useful to obtain the geometrical shape of the surface of test piece in macro and micro range. However, it is well known that the results of nanoindentation test become unstable in the nano range.

In this work, authors focused the geometry observation system for nanoindentation system. Confirmation the capability of PSISCM system and development of objective type atomic force microscopy to obtain the geometrical shape in nano range are examined. The AFM that has an excellent performance is developed by SII nanotechnology Inc. Japan, and it built into system. In many cases, it performs enough to observe the residual impression and the surface of the test piece. This system uses three methods to obtain the geometrical shape of surface in each range. Generally, AFM has the observation range at about several microns. It is difficult to search the small residual impression by only AFM. Before the observation of AFM, the observation area should be selected by using PSISCM. New measurement tool using PSISCM and AFM to obtain the surface geometry from macro range to nano range is proposed. This tool is very simple, quick and useful tool.
Surface Structure Characterization and Electrochemical Characteristics of Carbon-Coated Lithium Iron Phosphate (C-LiFePO4) Particles
Authors: Sun Xiangcheng , Sun Kai , Cui Bo
Published: November 2012

Carbon-coated lithium iron phosphate (C-LiFePO4) particles have been synthesized by a solid-state reaction process. Particles surface morphology, olivine-type phase structures and the carbon shell-core structures are investigated in details by transmission electron microscopy (TEM, HRTEM) imaging and electron diffraction (SAED) patterns. Homogenous features of carbon coating of the LiFePO4 particles surface are obviously revealed. HR-TEM imaging and X-ray photoelectron spectroscopy (XPS) confirmed an amorphous sp2 type conducting coating layer on the surface of LiFePO4 particles. Particles shape and size showed the clear single-crystal nature of the phospho-olivine type structures with the rough spherical features of 50-250 nm size range. The characteristics of sp2 type carbon-coating on the LiFePO4 particles surfaces allows improving the electrical conductivity and reducing the diffusion path of the lithium ions, as directly evidenced from electrochemical tests of charge-discharge cycling.
Temperature and Frequency Dependencies of Ferroelectric Properties in Rhombohedral Epitaxial Pb(Zr,Ti)O3 Films with Perfect (111) Orientations Grown on CaF2 Substrates.
Authors: Ehara Yoshitaka , Yamada Tomoaki , Iijima Takashi , Valanoor Nagarajan , Funakubo Hiroshi
Published: November 2012

Perfectly (111)-oriented rhombohedral Pb(Zr, Ti)O3 [PZT] films were successfully grown on (111) CaF2 substrates. These films have the polar-axis perpendicular to the substrate surface without non-180o domains. Well saturated polarization (P) –electric field (E) hysteresis loops were observed at various frequencies and temperatures. Temperature dependence of the saturation polarization (Psat.) was in good agreement with the estimated one by Haun et al. using phenomenological approach but did not strongly depend on the measured frequencies. On the other hand, the coercive field (Ec) increased with decreasing temperature and with increasing the measurement frequency.
Colloidal CuInS2 Based Nanocrystals /TiO2 Nanotube Arrays Composite Solar Cells Fabrication and Testing
Authors: Reddy Vanga R. , Wilson William , Eyi Rick , Wu Jiang , Manasreh M. O. , Dixion John , Wang Andrew
Published: November 2012

To develop alternative and low cost photovoltaic technologies we have synthesized CuInS2 nanocrystals with tunable optical properties and characterization was carried out thoroughly with TEM, SEM, EDAX and XRD. Furthermore large self-organized arrays of TiO2 nanotubes were fabricated on Ti foil followed by simple electrochemical anodization technique and characterized their structure by SEM and then for the first time coupled both the nanocrystals and nanotubes to form a p-n junction type photovoltaic device. The current-voltage (I-V) characteristics of photovoltaic cells were measured to test the proof of concept. Some preliminary experiments showed that device generates some current upon illumination. However, in our case we fabricated a device without sandwiching any buffer or barrier layers in between nanocrystals and nanotube arrays. We have been optimizing our solar cells efficiency by improving quality of nanotubes and nanocrystals. Some of the interesting finding are presented and discussed.
Poly(lactide-co-glycolide)-Hydroxyapatite Composites: The Development of Osteoinductive Scaffolds for Bone Regenerative Engineering
Authors: Deng Meng , Cushnie Emily K. , Lv Qing , Laurencin Cato T.
Published: November 2012

Regenerative engineering represents a new multidisciplinary paradigm to engineer complex tissues, organs, or organ systems through the integration of tissue engineering with advanced materials science, stem cell science and developmental biology. While possessing elements of tissue engineering, regenerative medicine, and morphogenesis, regenerative engineering is distinct from these individual disciplines since it specifically focuses on the integration and subsequent response of stem cells to biomaterials. One goal of regenerative engineering is the design of materials capable of inducing associated cells toward highly specialized functions. For example, the interaction of cells with calcium phosphate surfaces has proven to be an important signaling modality in promoting osteogenic differentiation. A biodegradable polymer-ceramic composite system has been developed from poly(lactide-co-glycolide) andin situsynthesized hydroxyapatite based on the three-dimensional sintered microsphere matrix platform. We have systematically optimized scaffold physico-chemical, mechanical, and structural properties for bone tissue regeneration applications by varying several parameters such as solution pH, polymer:ceramic ratio, sintering time and sintering temperature. The bioactivity of composite scaffolds is attributed to their ability to deliver calcium ions to surrounding medium and allow for reprecipitation of calcium phosphate on the scaffold surface. Furthermore, the composite scaffolds have demonstrated increased loading capacity of osteoinductive growth factor (BMP-2) and a more sustained release profile due to a greater number of adsorption sites provided by the ionic calcium and phosphate groups as well as a larger matrix surface area.In vitrocell studies were performed to investigate the efficacy of this composite system to induce osteogenic differentiation of human adipose-derived stem cells. Cells cultured on the ceramic containing scaffolds exhibited significantly higher expression of osteoblastic markers and greater extracellular matrix mineralization than non-ceramic containing scaffolds, indicating the potential for the ceramic phase to promote osteogenic differentiation. In addition, loaded BMP-2 retained its bioactivity as a mitogen and osteoinductive agent during the differentiation of adipose-derived stem cells into mature osteoblasts.In vivoevaluation using a critical-sized ulnar defect model in New Zealand white rabbits demonstrated the ability of composite scaffolds to support cellular infiltration throughout the scaffold pore structure and vascularization of new tissue, as well as facilitate formation of newly mineralized bone tissue. The work described herein provides strong evidence for the potential of polymer-ceramic composite scaffolds to function as osteoinductive bone graft substitutes, and paves the way for future development of advanced tissue-inducing materials.
Preparation of Nanoparticle-containing Aligned Collagen Fibers for Dense Connective Tissue Repair and Regeneration
Authors: Cheng Xingguo , Desai Sapna A.
Published: November 2012

Nanoparticles (NPs) loaded with human platelet-derived growth factor (h-PDGF) were prepared and characterized. These NPs were co-assembled with collagen to form highly aligned NP-collagen composite fibers by using an electrochemical process. PDGF can be released gradually from either NPs or aligned NP-collagen fibers. This investigation demonstrated a novel way to fabricate highly aligned composite fibers, which can locally release a growth factor in a controlled and gradual manner, potentially avoiding the fast clearance of the growth factor from the implantation site. Thus, the aligned NP-collagen fiber is a novel and promising implantation material for tendon/ligament repair and regeneration.
Preparation and In Vitro Characterization of Polycaprolactone and Demineralized Bone Matrix Scaffolds
Authors: Moloye Titilayo , Batich Christopher
Published: November 2012

Cylindrical porous polycaprolactone (PCL) scaffolds containing 25, 35, and 50 wt% demineralized bone matrix (DBM) were fabricated using a salt-leaching method for application in bone engineering. In the present work, PCL-DBM scaffolds were monitored for calcium and phosphorus deposition in both deionized (DI) water and simulated body fluid (SBF) for time periods of 5, 10, 15, and 20 days at 37°C under constant rotation. An in vitro assessment of the bioactivity of synthetic materials using SBF under physiological conditions can be used as a barometer of scaffold behavior in vivo. DBM, an osteoinductive material, was used to gauge if there was a correlation between the concentration of DBM within a scaffold and the apatite formation on its surface. Biochemical assays, alizarin red S staining, and scanning electron microscopy (SEM) with elemental analysis of calcium and phosphorus were consistent in that they confirmed that PCL scaffolds containing 35 wt% DBM in SBF at 14 days post-immersion showed signs of early apatite formation.
Neuronal Outgrowth and Differentiation on Poly(glycerol sebacate)
Authors: Casey Meghan E. , Jedlicka Sabrina S.
Published: November 2012

The importance of the extracellular mechanical environment in stem cell differentiation has been extensively studied over the last decade. In neuronal cell differentiation, matrix stiffness and neurite outgrowth have been correlated, highlighting the impact of matrix effects on neuronal cell morphology. In addition, on materials that approach the physiological mechanical properties of brain tissue, neurons from mixed phenotype primary cultures will prevail. However, if the same mixed culture is grown on polystyrene, glial populations are more prevalent. Enhancing the understanding of these differentiation processes will further expand the ability to design materials for neuronal implants that are conducive to neuronal survival, resist glial scarring and promote neurite outgrowth and cell connectivity. Specifically, elastomers such as poly(glycerol sebacate) (PGS) hold promise in neuronal tissue engineering, due to their mechanical tunability. PGS is biocompatible, biodegradable and possesses mechanical properties similar to that of living tissue. Neuronal cell differentiation was studied on PGS, using P19 embryonic carcinoma cells, which can be differentiated into a neuronal phenotype using retinoic acid. Varying cure temperatures of PGS including 120°, 140° and 165°C were selected, which equate to an elastic modulus of 0.07, 0.43 and 2.30 MPa respectively. Cells were characterized via immunocytochemistry. A primarily astrocytic population, with limited neuronal differentiation and neurite outgrowth were observed on the PGS 120°C. Cells grown on PGS 140°C demonstrated marked neurite outgrowth, with an increase in neuronal cells. Cells grown on the PGS 165°C exhibited the largest population of neurons, with significant neurite outgrowth. These results indicate that substrate mechanical properties do impact neuronal differentiation, but that a material with a Young’s modulus similar to that of neuronal tissue (PGS 120°C) may not necessarily be the most conducive to in vitro differentiation.
Ultrafast Charge Carrier Dynamics and Photoelectrochemical Properties of Hydrogen-treated TiO2 Nanowire Arrays
Authors: Wheeler Damon A. , Wang Gongming , Fitzmorris Bob C. , Adams Staci A. , Li Yat , Zhang Jin Z.
Published: November 2012

Here we report studies of photoelectrochemical (PEC) properties and ultrafast charge carrier relaxation dynamics of hydrogen-treated TiO2 (H:TiO2) nanowire arrays. PEC measurements showed the photocurrent density of the H:TiO2 was approximately double that of TiO2, attributed to increased donor density due to the formation of oxygen vacancies in H:TiO2 due to hydrogen treatment Charge carrier dynamics of H:TiO2, measured using fs transient absorption spectroscopy, showed a fast decay of ∼20 ps followed by slower decay persisting to tens of picoseconds. The fast decay is attributed to bandedge electron-hole recombination and the slower decay is attributed to recombination from trap states. Visible absorption is attributed to either electronic transitions from the valence band to oxygen vacancy states or from oxygen vacancy states to the conduction band of the TiO2, which is supported by incident photon to current conversion efficiency (IPCE) data. H:TiO2 represents a unique material with improved photoelectrochemical properties for applications including PEC water splitting, solar cells, and photocatalysis.
Synthesis and characterization of carbon nanotube\iron oxide hybrids
Authors: Souza Lígia P. , Ferreira Thais M. , Franco Juliana R. , de Oliveira Sergio , Geraldo Viviany , Munford Maxmiliano L. , Ferlauto Andre S.
Published: November 2012

In this work, the synthesis of carbon nanotubes/hematite hybrids was investigated. The hybrids were produced by solvothermal method and a systematic study exploring different reaction parameters such as treatment duration, temperature and solvent was performed. Results from different characterization techniques demonstrate that the CNTs were effectively decorated with hematite (α-Fe2O3). The size and concentration of the NPs varies with the reaction parameters and the smallest obtained NPs have ∼100 nm diameter. It was demonstrated that translucent and homogeneous thin films made of the resulting hybrid material can be deposited on indium-tin oxide substrates by electrophoretic deposition or by vaccum filtration.
Breast Adenocarcinoma Cell Functions on Nanopatterned PLGA Surfaces
Authors: Zhang Lijuan , Webster Thomas J.
Published: November 2012

The effects of poly (lactic-co-glycolic acid) (PLGA) surface properties on lung epithelial carcinoma cell functions were previously identified. Results demonstrated decreased lung epithelial carcinoma cell vascular endothelial growth factor (VEGF) synthesis on 23 nm surface featured PLGA compared to the PLGA nano-smooth substrates. To investigate the universality of nanopatterned PLGA on inhibiting cancer cell functions, here, breast epithelial adenocarcinoma cell, MCF-7, early functions were determined on different PLGA nanometer surface topographies. Moreover, the viability of healthy breast cells was determined by an MTT assay to investigate the effects of nanopatterning on healthy breast cell growth. Atomic force microscopy (AFM) verified the varied nanotopographies on the PLGA surfaces prepared in this study. Importantly, results demonstrated significantly decreased breast adenocarcinoma cell functions (including decreased proliferation rate and decreased VEGF synthesis) on 23 nm featured PLGA surfaces compared to the other PLGA surface topographies (specifically, nano-smooth, 300 nm and 400 nm surface featured PLGA surfaces). In contrast, healthy breast epithelial cell studies indicated a 24% higher cell proliferation on the 23 nm featured PLGA surfaces compared to all other PLGA samples. In summary, these results provided further insights into understanding the role surface nanotopographies can have on selectively inhibiting cancer cell functions for a wide range of anti-cancer applications.
PbS Nanoparticles: Synthesis, Supercritical Fluid Deposition, and Optical Studies
Authors: Wang Joanna S. , Ullrich Bruno , Brown Gail J.
Published: November 2012

Lead sulfide (PbS) nanoparticles (NPs) of different sizes (2.0 nm - 14.4 nm) have been synthesized in our laboratory. By using those NPs, we formed colloidal films on glass and GaAs substrates employing a specialized supercritical fluid CO2 (sc-CO2) deposition method. The deposited films contain only the PbS NPs and the protecting group of oleic acids and require no polymer matrix. The NP films are solvent free, environmentally stable, and show good adhesion to the substrates. The sc-CO2 deposition process can deposit films ranging in thickness from a few monolayers, in well ordered arrays, up to 0.5 μm or greater. The photoluminescence (PL) properties of these nano-structured films were studied with Fourier transformation infrared spectroscopy from 5 K up to 300 K.
Ferromagnetism in Nanocrystalline Powders and Thin Films of Cobalt-Vanadium co-doped Zinc Oxide
Authors: Gálvez-Saldaña Marco , Montes-Albino Gina , Perales-Perez Oscar
Published: November 2012

A systematic study was carried out to determine the effect of the composition and annealing atmosphere (air and N2) on the structural, optical and magnetic properties of pure, doped and co-doped ZnO [Zn(1-y)(CoV)yO] nanocrystalline powders and films. The (Co+V) doping level, ‘y’, was fixed at 2 at% with variable individual concentrations of Co and V species. Powders and films were synthesized via a sol-gel approach where the films were grown on silicon (100) substrates. X-ray diffractometry verified the formation of the ZnO host structure after annealing of the precursor phases. The variation of the average crystallite size of Co-V (2 at.%) ZnO powders annealed in air at 500°C were negligible and averaged 33 nm. Photoluminescence (PL) measurements of powder corroborated the formation of high-quality ZnO host structure, as well as in films annealed in air. In turn, XRD and PL measurements confirmed an enhanced crystallinity of the ZnO host, with an average crystallite size of 41 nm, for films annealed at 500°C under a N2 atmosphere. M-H measurements evidenced a ferromagnetic behavior at room temperature in powders and films that was dependent on the type and amount of the dopant species.
Electrical Characterization of Electrochemically Grown ZnO Nanorods using STM
Authors: Suzuki Yuji , Ibheanacho Bright , Ahnood Arman , Kathirgamanathan Poopathy , Wong William , Nathan Arokia
Published: November 2012

ZnO nanorods were grown homogenously and vertically on ITO using electrochemical techniques. The physical properties of the nanorods were characterized using SEM and optical absorption. The electrical conductivity, deduced using STM at different tip heights, and was found to be 20 Ω-cm with a carrier concentration of 3x1015 cm-3.The results show that electrochemically grown ZnO nanorods have electrical properties suitable for use in electronic devices such as solar cells and transistors. A-Si:H p-i-n solar cells were then deposited after the fabrication on the ZnO on ITO-coated substrates. The results show that the textured solar cell performance was 30% higher than the planar solar cell.
Enhanced mobility of hydrogenated MO-LPCVD ZnO contacts for high performances thin film silicon solar cells
Authors: Ding L. , Benkhaira M. , Nicolay S. , Ballif C.
Published: November 2012

In this contribution, we study the increase in metalorganic-low pressure chemical vapor deposited (MO-LPCVD) ZnO thin films conductivity by hydrogen plasma post-treatment. We show that this improvement is linked to defect passivation at grain boundaries, decreasing the electron traps density and resulting in the almost complete suppression of the electron scattering at grain boundaries. For a 2 μm thick non-intentionally doped ZnO layer, electron mobility reaches after treatment values close to 60 cm2V-1s-1 (corresponding to an increase of 100%), with a carrier density still as low as 3 x1019 cm-3 (+1.5 x1019 cm-3). Such layers have an absorbance below 2-3% in the range of 400 to 1100 nm making them among the most transparent and conductive materials reported so far. In addition, we demonstrate that hydrogen plasma post-treated ZnO layers can be used as front electrode for producing highly transparent and conductive electrodes. Eventually, it is shown that hydrogen plasma treatment can also be used on the complete thin film solar cell stack (back contact and silicon device) to improve the cell performances.
Enhanced Light Trapping of Thin Film Si Solar Cell in Glass-Laminated Module
Authors: Sugiyama Takashi , Chonan Kousuke , Kambe Mika
Published: November 2012

In efforts to achieve higher efficiency of thin film Si solar cell, light trapping is one of the most important strategies in designing the cell structure. From the past studies, it is well known that TCO with a higher haze can exhibit better light trapping characteristics for a superstrate type thin film Si solar cell, while such TCO could give lower Voc and FF values caused by steep valleys in the texture of TCO. Furthermore, TCO with too high haze in a longer wavelength region could make back reflectance at the Ag rear electrode/reflector lower due to plasmonic effect on rough surface of Ag and thus reduces the efficiency of light trapping. In order to solve this contradictory behavior of light trapping in a conventional thin film Si solar cell, we have newly developed a glass-laminated module of thin film Si solar cell which has enhanced light trapping without deteriorating Voc nor high reflectance of Ag rear reflector.
High-Rate Deposition of Intrinsic a-Si:H and μc-Si:H Layers for Thin‑Film Silicon Solar Cells using a Dynamic Deposition Process
Authors: Zimmermann T. , Flikweert A. J. , Merdzhanova T. , Woerdenweber J. , Gordijn A. , Dybek K. , Stahr F. , Bartha J. W.
Published: November 2012

Thin‑film silicon solar cells based on hydrogenated amorphous silicon (a‑Si:H) and hydrogenated microcrystalline silicon (μc‑Si:H) absorber layers are typically deposited using static plasma-enhanced chemical vapor deposition (PECVD) processes. It has been found that the use of very‑high frequencies (VHF) is beneficial for the material quality at high deposition rates when compared to radio-frequency (RF) processes. In the present work a dynamic VHF‑PECVD technique using linear plasma sources is developed. The linear plasma sources facilitate the use of very-high excitation frequencies on large electrode areas without compromising on the homogeneity of the deposition process. It is shown that state-of-the-art a‑Si:H and μc‑Si:H single-junction solar cells can be deposited incorporating intrinsic layers grown dynamically by VHF-PECVD at 0.35 nm/s and 0.95 nm/s, respectively.
Anfis to estimate discharge capacity of rectangular side weir
Authors: Kisi Ozgur , Bilhan Omer , Emiroglu M. Emin
Published: November 2012

The adaptive neuro-fuzzy inference system (Anfis) is considered for flow over rectangular side weirs located on a straight channel as a substantial part of distribution channels in irrigation systems and treatment units. To estimate the outflow over a rectangular sharp-crested side weir, the discharge coefficient in the side weir equation needs to be determined in accordance with the effective dimensionless parameters F1 (Froude number), L/b (weir length/channel width), L/h1 (weir length/flow depth), and p/h1 (weir height/flow depth). The discharge coefficient of rectangular side weirs was determined using 843 laboratory test results. The performance of the Anfis model is compared with multilinear and nonlinear regression models. The criteria used for the evaluation of the performance of models are root mean square errors (RMSE), mean absolute errors (MAE) and correlation coefficient (R) statistics. Comparison results indicated that the Anfis technique could be successfully employed in modelling discharge coefficients. It is found that the Anfis model with RMSE of 0·043 in the test period is superior in estimation of discharge coefficient than the multiple nonlinear and linear regression models with RMSE of 0·054 and 0·106, respectively.
Distribution and drivers of ectomycorrhizal fungal communities across the North American Arctic
Authors: Timling I. , Dahlberg A. , Walker D. A. , Gardes M. , Charcosset J. Y. , Welker J. M. , Taylor D. L.
Published: November 2012

Ectomycorrhizal fungi (EMF) form symbioses with a few plant species that comprise a large fraction of the arctic vegetation. Despite their importance, the identity, abundance and distribution of EMF in the Arctic, as well as the key drivers controlling their community composition are poorly understood. In this study, we investigated the diversity and structure of EMF communities across a bioclimatic gradient spanning much of the North American Arctic. We collected roots from two principal arctic ectomycorrhizal host plants, Salix arctica and Dryas integrifolia, typically growing intermingled, at 23 locations stratified across the five bioclimatic subzones of the Arctic. DNA was extracted from ectomycorrhizal root tips and the ITS region was sequenced and phylogenetically analyzed. A total of 242 fungal Operational Taxonomic Units (OTUs) were documented, with 203 OTUs belonging to the Basidiomycota and 39 to the Ascomycota, exceeding the number of previously morphologically described EMF in the Arctic. EMF communities were dominated by a few common and species‐rich families such as Thelephoraceae, Inocybaceae, Sebacinaceae, Cortinariaceae, and Pyronemataceae. Both host plants showed similar species richness, with 176 OTUs on Salix arctica and 154 OTUs on Dryas integrifolia. Host plant identity did not affect EMF community composition. The ten most abundant OTUs had a wide geographic distribution throughout the Arctic, and were also found in boreal, temperate and Mediterranean regions, where they were associated with a variety of hosts. Species richness did not decline with increasing latitude. However, EMF community structure changed gradually across the bioclimatic gradient with the greatest similarity between neighboring bioclimatic subzones and locations. EMF community structure was correlated with environmental factors at a regional scale, corresponding to a complex of glaciation history, geology, soil properties, plant productivity and climate. This is the first large‐scale study of EMF communities across all five bioclimatic subzones of the North American Arctic, accompanied by an extensive set of environmental factors analyzed to date. While our study provides baseline data to assess shifts of plant and fungi distribution in response to climate change, it also suggests that with ongoing climate warming, EMF community composition may be affected by northward shifts of some taxa.
Effects of Once‐Daily Tadalafil on Treatment Satisfaction, Psychosocial Outcomes, Spontaneous Erections, and Measures of Endothelial Function in Men With Erectile Dysfunction But Naive to Phosphodiesterase Type 5 Inhibitors
Authors: Porst Hartmut , Brock Gerald B. , Kula Krzysztof , Moncada Ignacio , Montorsi Francesco , Basson Bruce R. , Kinchen Kraig , Aversa Antonio
Published: November 2012

Abstract: Previous studies established the efficacy of once‐daily tadalafil for men with erectile dysfunction. However, no trial has focused on the effects of such treatment on men without previous experience using oral phosphodiesterase type 5 inhibitors. Patients were randomized (2:1) to once‐daily tadalafil 5 mg (with possible down‐titration to 2.5 mg; n = 146) or placebo (n / 69) for 12 weeks. Among 215 patients (mean age, 52 years), once‐daily tadalafil treatment resulted in 61.7% of study participants reporting their ability to achieve and maintain erections as being much better or very much better (vs 21.7% on placebo; P < .001). Tadalafil significantly improved treatment satisfaction on the Erectile Dysfunction Inventory of Treatment Satisfaction (P < .001 vs placebo at end point) and psychosocial outcomes on the Self‐Esteem and Relationship (SEAR) questionnaire (least squares mean difference in SEAR total score change from baseline, 11.8 [95% confidence interval, 5.4%–18.2%; P < .001 vs placebo]). Patients receiving once‐daily tadalafil also experienced a higher proportion of daily self‐reported spontaneous morning erections at end point (58.7%) compared with placebo (42.2%; P < .001 for the between‐treatment difference in changes from baseline). However, no significant differences in parameters of endothelial dysfunction (including biomarkers and peripheral arterial tonometric measures) or nocturnal erections as recorded by the nocturnal electrobioimpedance volumetric assessment were observed between treatment groups. Tadalafil was well tolerated; adverse events included back pain, headache, and dyspepsia. These findings may contribute to a more comprehensive understanding of once‐daily tadalafil's effects on phosphodiesterase type 5 inhibitor–naive men.
Evaluation of Testicular Sperm CRISP2 as a Potential Target for Contraception
Authors: Muñoz Mariana Weigel , Ernesto Juan I. , Bluguermann Carolina , Busso Dolores , Battistone María A. , Cohen Débora J. , Cuasnicú Patricia S.
Published: November 2012

Abstract: Cysteine‐rich secretory protein 2 (CRISP2) is a testicular sperm protein proposed to be involved in fertilization. With the aim of examining the relevance of CRISP2 for fertility and its potential use as a target for contraception, in the present work, male and female rats were immunized with recombinant CRISP2 coupled to maltose‐binding protein (MBP) and evaluated for their subsequent fertility. As controls, animals were injected with either MBP or recombinant CRISP1. Enzyme‐linked immunosorbent assay of sera collected at different intervals after immunization indicated that CRISP2 immunization raised specific antibodies in both sexes, with levels that increased as a function of time. Western blot studies revealed that anti‐CRISP2 sera were capable of recognizing CRISP2 in testicular, epididymal, and sperm extracts, whereas histological studies showed no evidence of autoimmune orchitis or epididymitis. Indirect immunofluorescence experiments revealed the ability of anti‐CRISP2 sera to recognize the native sperm protein in fresh, capacitated, and ionophore‐induced acrosome–reacted cells. Moreover, anti‐CRISP2 sera significantly inhibited the sperm ability to penetrate zona‐free eggs, confirming the role of CRISP2 in rat gamete fusion. In spite of the presence of circulating anti‐CRISP2 antibodies capable of inhibiting the sperm fertilizing ability, mating studies revealed no effects of CRISP2 immunization on male or female fertility, in contrast to the significant inhibition observed in both sexes in animals injected with CRISP1. Together, these observations indicated the immunogenic properties of testicular CRISP2 but do not support CRISP2 as a target for immunocontraception or as a molecule responsible for generating autoimmune orchitis or immunoinfertility.
Antiandrogenic Activity of Resveratrol Analogs in Prostate Cancer LNCaP Cells
Authors: Iguchi Kazuhiro , Toyama Tomoaki , Ito Tetsuro , Shakui Toshinobu , Usui Shigeyuki , Oyama Masayoshi , Iinuma Munekazu , Hirano Kazuyuki
Published: November 2012

Abstract: The suppression of androgen signaling is a therapeutic target for the treatment of prostate cancer. Resveratrol (3,4′,5‐trihydroxystilbene) is known to inhibit the function of the androgen receptor (AR). In the present study, we investigated the antiandrogenic activities of resveratrol analogs in order to identify a potent antiandrogen compound. Resveratrol analogs were isolated from plants or were semisynthesized from resveratrol. AR transcriptional activity was measured in prostate cancer LNCaP cells using a luciferase assay with the MMTV‐luc reporter plasmid. Among the resveratrol analogs tested, 4′‐O‐methylresveratrol (3,5‐dihydroxy‐4′‐methoxystilbene) was the most effective inhibitor of AR transcriptional activity. Introduction of a methoxy group to the C‐4′ of resveratrol and its analogs increased their antiandrogenic activity compared with the unmodified counterparts. Conversely, modification of the 3‐ and/or 5‐hydroxyl groups reduced the antiandrogenic activity. 4′‐O‐methylresveratrol was more effective than resveratrol in inhibiting Akt phosphorylation, which is related to AR signaling, in LNCaP cells. The hydroxyl groups in resveratrol play a key role in their antiandrogenic effect by modulating AR transcriptional activity.
Dietary Fat Modulates the Testosterone Pharmacokinetics of a New Self‐Emulsifying Formulation of Oral Testosterone Undecanoate in Hypogonadal Men
Authors: Yin Anthony , Alfadhli Eman , Htun Michelle , Dudley Robert , Faulkner Sandra , Hull Laura , Leung Andrew , Bross Rachelle , Longstreth James , Swerdloff Ronald , Wang Christina
Published: November 2012

Abstract: This study investigates the effect of dietary fat on the testosterone (T) pharmacokinetics in hypogonadal men following administration of a self‐emulsifying capsule formulation of oral T undecanoate (TU). In an open‐label, 2‐center, 5‐way crossover study, a single oral dose of TU containing 300‐mg equivalents of T (maximum anticipated human dose per administration) wasadministeredto16hypogonadal menwith a washout period of at least 5 days between doses. All participants were randomized to receive the TU capsules fasting or 30 minutes after an approximately 800‐calorie meal containing 10%, 20%, 30%, or 50% fat. Serial blood samples were collected from 2 hours predose to 25 hours postdose to determine serum T and dihydrotestosterone (DHT) by liquid chromatography tandem mass spectrometry. Administering TU with a meal increased serum T concentrations, with the magnitude of the increase being directly dependent on the amount of fat in the meal. Average and peak serum T concentrations and area under the curve increased as the fat content of the meal was increased. Neither the high‐fat meal (50% fat) nor the lower‐fat meal (20% fat) showed a significant food effect relative to the normal‐fat (Western diet) meal (30% fat). However, administering TU while fasting resulted in 50% or less of the cumulative exposure obtained when administered with 20%‐ to 50%‐fat meals (albeit still substantial). A very‐low‐fat meal (10% fat) showed a significant food effect relative to the normal meal, but still exceeded the fasting condition by approximately 50%. Serum DHT concentrations showed corresponding increases to the serum T. As expected with the maximum anticipated clinical dose of TU (300 mg T), oral administration of this new formulation with food containing 20% to 50% dietary fat produced T levels at or above the upper range of adult men, and T levels trended higher as dietary fat content increased. Only with a very‐low‐fat diet (10%) or in a fasted state did a clinically significant food effect occur, but even then sufficient TU was absorbed with the self‐emulsifying TU formulation to produce average serum T concentration predicted to be in the normal reference range (10 to 35 nmol/L).
Management of Erectile Dysfunction: Great Progress, Greater Promise
Authors: Burnett Arthur L. , Hellstrom Wayne J. G.
Published: November 2012

Abstract: Sexual medicine, exemplified by the management of erectile dysfunction, is a traditional pillar of andrology. Erectile dysfunction has received the greatest attention within the specialty area and its management models the progress of the field more generally. This review provides a perspective of the history and contemporary practice of erectile dysfunction management, highlighting aspects of basic science research, epidemiology, and clinical care. Furthermore, the impact of this field as a major health concern in correlation with basic aspects of wellness and disease is acknowledged. The field continues to evolve as a legitimate discipline in medicine and is worthy of ongoing scientific support and activity.