bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Optical Absorption of Indium Sulfide Nanorod Arrays Formed by Glancing Angle Deposition
Authors: Cansizoglu Mehmet , Engelken Robert , Seo Hye-Won , Karabacak Tansel 
Published: September 2009

AbstractIndium (III) sulfide has recently attracted much attention due to its potential in optical sensors as a photoconducting material and in photovoltaic applications as a wide direct bandgap material. On the other hand, optical absorption properties are key parameters in developing highly photosensitive photodetectors and high efficiency solar cells. We show that indium sulfide nanorod arrays produced by glancing angle deposition techniques have superior absorption and low reflectance properties compared to conventional flat thin film counterparts. We observed an optical absorption value of approximately 96% for nanorods, in contrast to 80% for conventional amorphous-to-polycrystalline thin films of indium sulfide. A photoconductivity response was also observed in the nanorod samples, whereas no measurable photoresponse was detected in conventional thin films. We give a preliminary description of the enhanced light absorption properties of the nanorods by using Shirley-George Model that predicts enhanced diffuse scattering and reduced reflection of light due the rough morphology.
Conduction Band Edge of TiO2-SnO2 Solid Mixtures Tuning for Photoelctrochemical Applications
Authors: Simiyu Justus , Aduda Bernard , Mwabora Julius Mwakondo 
Published: September 2009

AbstractWe report investigation of effect of conduction band edge on the dye injection and transport by preparation of (Ti,Sn)O2 solid mixtures in ratios of 80:20 and 90:10 as possible applications in dye sensitized solar cells. SEM micrographs showed highly porous with nanometer sized particles of around 6 - 10μm diameter. X-ray diffraction patterns showed strong TiO2 anatase peaks with crystal orientation directions (101) being the strongest in both the solid mixtures and in pure TiO2. XPS studies have shown an apparent chemical shift for Ti 2p and O1s core level spectra with an energy difference between the unmodified and the solid mixture being 0.65eV. Initial I-V studies have shown high Voc but low short circuit photocurrent, showing a possible unfavorable band edge shift between the semiconductor and the dye LUMO level.
Hybrid Gold Architectures for Sensing and Catalytic Applications
Authors: Song Hyunjoon 
Published: September 2009

AbstractExquisite control of surface functionality is essential to tailor the chemical and physical properties of metal nanocrystals to the requirements of specific applications. Hybridization of gold nanoparticles with other components such as polymers and metal oxides can effectively introduce appropriate functionalities on the surface without changing their own properties, and thereby become a basic architecture for various applications such as sensors and catalysts. In the present work, we report two hybrid nanostructures comprising gold nanocrystals. PDMAEMA (poly(dimethylaminoethylmethacrylate))–gold hybrid nanocrystals were synthesized via a polyol process, which produced carboxylate functionality on the gold surface. This hybrid structure was employed for a sensitive pH-sensor in solution. On the other hand, porous silica-gold hybrid nanoreactors were produced by selective etching of gold cores from gold@silica core-shell particles. The nanoreactor framework exhibited high and controllable activity on the reduction of aromatic nitroxides. These two examples of hybrid gold architectures would be able to apply for other metal and metal oxide systems to develop biosensors and energy production catalysts.
Seedless Templated Growth of Hetero-Nanostructures for Novel Microelectronics Devices
Authors: Iacopi Francesca , Rooyackers Rita , Loo Roger , Vanherle Wendy , Milenin Alexey , Arstila Kai , Verhulst Anne , Takeuchi Shotaro , Bender Hugo , Caymax Matty , Hantschel Thomas , Vandooren Anne , Vereecken Philippe M , De Gendt Stefan , Heyns Marc 
Published: September 2009

AbstractThe feasibility of a templated seedless approach for growing segmented p-i-n nanowires –based diodes based on selective epitaxial growth is demonstrated. Such diodes are the basic structure for a TunnelFET device. This approach has the potential for being easily scalable at a full-wafer processing, and there is no theoretical limitation for control on nanowires growth and properties when scaling down their diameters, as opposed to an unconstrained vapor-liquid-solid growth. Moreover, Si/SixGe1-x hetero-structures are implemented, showing that this can improve the TFET ON current not only thanks to the lowered barrier for the band-to-band source-channel tunneling, but additionally thanks to its lower thermal budget for growth, allowing for better control of the abruptness of the doping profile at the source-channel tunneling interface.
Synthesis and Electrical Characterization of Tin Oxide Nanostructures
Authors: Berengue Olivia Maria , Dalmaschio Cleocir J. , Conti Tiago G. , Chiquito Adenilson J. , Leite Edson R. 
Published: September 2009

AbstractSn3O4 nanobelts were grown by a carbothermal evaporation process of SnO2 powders in association with the well known vapour-solid mechanism (VS). The nanobelts crystal structure was investigated by x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), raman spectroscopy and field emission gun scanning electron microscopy (FEG-SEM). The structural and morphological characterization has confirmed the growth of single crystal nanobelts. The electrical characterization (current-voltage, temperature-dependent resistance curves) of individual Sn3O4 nanobelts was performed at different temperatures and light excitation. The experiments revealed a semiconductor – like character as evidenced by the resistance decreasing at high temperatures. The transport mechanism was identified as the variable range hopping.
Optical and Electrical Properties of TiO2 Nanotubes Grown by Titanium Anodization
Authors: Alivov Yahya , Kuryatkov Vladimir , Pandikunta Mahesh , Rajanna Gautam , Johnstone Daniel , Bernussi Ayrton , Nikishin Sergey A , Fan Z. Y. 
Published: September 2009

AbstractIn this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va<60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.
Mechanical Properties of Polymer Blends Having Shape-memory Capability
Authors: Behl Marc , Ridder Ute , Wagermaier Wolfgang , Kelch Steffen , Lendlein Andreas 
Published: September 2009

AbstractThe general design principle of shape-memory polymers (SMP) requires two key compo-nents: covalent or physical crosslinks (hard domains) determining the permanent shape and switching domains fixing the temporary shape as well as influencing the switching temperature Tsw. In conventional thermoplastic SMP hard and switching domains determining segments are combined in one macromolecule, e.g. block copolymers such as polyurethanes. Recently, binary polymer blends having shape-memory properties, from two different multiblock copolymers have been presented, whereby the first one is providing the segments forming hard domains and the second one the segments forming the switching domains. Besides the shape-memory proper-ties, the mechanical properties of such materials are application relevant. Here we investigate how the blend composition influences mechanical properties of this new class of shape-memory materials.
Multiphase Polymer Networks with Shape-Memory
Authors: Kelch Steffen , Behl Marc , Kamlage Stefan , Lendlein Andres 
Published: September 2009

AbstractTailoring of properties and functions of shape-memory polymer networks to the requirements of specific applications demands a knowledge-based approach. A comprehensive database enabling the analysis of structure-property relationships is obtained by the systematic variation of molecular parameters. In detail we investigated the influence of the nature of thermal transition on the shape-memory behavior of polymer networks. Furthermore, additional amorphous phases were introduced enabling tailoring of elastic properties especially in the temporary shape as a consequence of the formed polymer morphology. Enabling higher elasticity, adjustable hydrolytic degradability, and the possibility to tailor the transition temperature of shape-memory to a temperature between room temperature and body temperature are considered to be substantial steps to improve the applicability of these active polymers in medicine.
Shape-Memory Properties of Radiopaque Micro-Composites from Amorphous Polyether Urethanes Designed for Medical Application
Authors: Cui Jing , Kratz Karl , Lendlein Andreas 
Published: September 2009

AbstractBiocompatible shape-memory polymers are of high significance for application in medical devices or instruments for minimally invasive surgery. To follow the medical device placement or changes in shape of the device in vivo by imaging methods like X-ray techniques, radiopacity of the polymer is required. In this work, we explored the shape-memory properties of radiopaque polymer composites prepared by incorporation of barium sulphate micro-particles in a biomedical grade polyether urethane (PEU) by co-extrusion technique. The filler content was varied from 5 wt% to 40 wt%, which was confirmed by thermal gravimetric analysis (TGA) measurements, while the particle distribution was visualized by scanning electron microscopy (SEM). The thermal and mechanical properties of the composites were investigated by means of dynamic mechanical analysis at varied temperature (DMTA) and tensile tests. The shape-memory properties of PEU composites were quantified in cyclic, thermomechanical experiments.
A significant increase in Young’s modulus and a decrease in elongation at break were observed for PEU composites with increasing content of BaSO4, while the DMTA results were not affected by incorporation of the fillers. All samples exhibited excellent shape-memory properties with shape fixity rates (Rf) above 98% and values for shape recovery rate (Rr) in the range of 81% to 93%. The maximum stress (σmax) obtained under constant strain recovery conditions increased from 0.6 MPa to 1.4 MPa with raising amount of BaSO4, while the corresponding temperature (Tσ,max) as well as the switching temperature (Tsw) determined under stress-free conditions remained constant for all polymer composites.
Thermomechanical Behaviour of Biodegradable Shape-memory Polymer Foams
Authors: Madbouly Samy A , Kratz Karl , Klein Frank , Lüetzow Karola , Lendlein Andreas 
Published: September 2009

AbstractShape-memory polymer foams based on poly(ω-pentadecalactone) (PPDL) and poly(ε-caprolactone) (PCL) multiblock copolymer with 60 wt% PCL content were prepared by environmentally-friendly high pressure supercritical carbon dioxide scCO2 foaming technique. A foam with a density of approximately 0.11 ± 0.02 g/cm3 and an average pore size of 150-200 μm with excellent compressibility and shape-memory properties was created at 25 bar/s depressurization rate in the temperature range between 78 and 84 °C. The shape-memory behavior of this foam was investigated using different programming modules, such as, under stress-free condition and under constant strain condition. The thermally-induced shape-memory effect (SME) was found to be strongly dependent on the programming conditions. Excellent shape fixity has been observed for all foams indicating the high efficiency of the switching domains to fix the temporary shape by crystallization. The stress recovery of this foam could be controlled by changing compression percentage (εc%) at a constant compression temperature. The production of these foams with unprecedented properties by commercially available processing equipment raises much hope with the potential to provide new materials with a unique combination of shape-memory properties and porous structure as well as desired properties for many industrial and biomedical applications
The Normal and Shear Strength of the Cell-Implant Interface: Accelerated Negative Buoyancy as a Method of Cell Adhesion Assessment
Authors: Griffiths Helen J , Collier Charles Andrew , Clyne T William 
Published: September 2009

AbstractThe strength of adhesion at the cell-substrate interface is an important parameter in the design of many prosthetic implant material surfaces, due to the desire to create and maintain a strong implant-tissue bond. This study focuses on the mechanical strength of the interface and the ease of cell removal from ceramic coatings using normal and shear forces, but also looks at cell proliferation rates on the same series of surfaces.

This systematic study of cell proliferation and adhesion has been carried out on a series of oxide coated Ti6Al4V based substrates with a range of surface morphologies and chemistries. Oxide coatings were formed using Plasma Electrolytic Oxidation (the PEO process).
Cells were seeded at a low concentration onto substrates and proliferation monitored for up to three weeks. The same cell concentrations were seeded on samples for adhesion testing. These were cultured for a few days to ensure well established adhesion of viable cells. The normal and shear strength of osteoblasts (bone cells) and chondrocytes (cartilage cells) adhered to these substrates was measured using accelerated negative buoyancy within an ultracentrifuge.

The variation in proliferation rates on, and adhesive strengths to, the range of coatings, is discussed and related to morphological and chemical differences in the coatings. A comparison is made between the normal and shear strengths of the cell-coating bonds and the differences between the behaviour of the two cell types discussed.
The MAESFLO Device: A Complete Microfluidic Control System
Authors: Goulpeau Jacques , Taniga Vélan , Kieffer Charles-André 
Published: September 2009

AbstractIn spite of considerable efforts, flow control in micro-channels remains a challenge owing to the very small ratio of channel/supply-system volumes, as well as the induction of spurious flows by extremely small pressure or geometry changes. We present here a robust and complete system for flow control in complex microchannel network that both monitors and controls all the flow relevant parameters, that is to say flow rate and pressure. Based on a dynamic control of reservoir pressures at the end of each channel and external thermal flow-sensors, all the parameters are measured with a precision down to 25 μBar and 2nL/min. Thanks to adaptative feed back control loop, the MAESFLO can control either the flow rate or the pressure with high stability over long period whatever the microsystem characteristics. Compared to classic pumps, a significant increase of stability has been reached as no mechanical parts are involved. Indeed the flow rate is pulse free and is stable down to 0.1% of the full scale. Besides, pressure control enables to achieve short response time (less than hundreds of millisec). The MAESFLO is thus a unique system to control flow in complex network architecture and can be considered as an alternative to integrated micro-valves using only external equipments. Indeed, the MAESFLO can stop the flow to nearly zero in one or several branches of a complex microfluidic network while keeping other flows constant. Sequential manipulation of liquids in a definite part of a micro-device is thus possible without expensive and time consuming fabrication processes. It can be particularly useful when dealing with washing steps in the case of biological assay for example. Controlling flow with short response time along with high precision is also a key issue in microfluidic. By combining pressure actuation with flowrate monitoring, short response time are achievable keeping a high precision flow rate. It can be particularly useful for droplet generation and size control, droplet on demand generation, long time living cell perfusion and drug injection… In this work we will present the benefit to control and monitor both pressure and flow rate with the MAESFLO. A lot of information can be extracted from these simple parameters, as hydraulic resistance, monophasic and biphasic apparent viscosity, the volume and the position of a trapped air bubble and many more. The proof of concept of stop flow control will also be shown with experimental results stressing the advantages of the “virtual micro-valve”.
Miniaturized Silicon Apertures for Lipid Bilayer Reconstitution Experiments
Authors: Goryll Michael , Chaplot Nipun 
Published: September 2009

AbstractIon channels reconstituted into lipid bilayer membranes can be used as a very sensitive and selective platform for high-throughput drug screening applications. In order to employ suspended lipid bilayer membranes for these experiments in form of a “lab-on-a-chip” configuration, a robust and affordable platform is required. In our study, we investigated the feasibility of hosting lipid bilayer membranes across micron-size apertures ranging from 5 μm – 50 μm in silicon. On these substrates, lipid bilayers were formed and characterized concerning their seal resistance, capacitance and breakdown voltage. Seal resistance values of up to 60 GΩ could be achieved repeatedly on these substrates.
Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems
Authors: Ileri Nazar , Létant Sonia E. , Britten Jerald , Nguyen Hoang , Larson Cindy , Zaidi Saleem , Palazoglu Ahmet , Faller Roland , Tringe Joseph W. , Stroeve Pieter 
Published: September 2009

AbstractNanoporous devices constitute emerging platforms for selective molecule separation and sensing, with great potential for high throughput and economy in manufacturing and operation. Acting as mass transfer diodes similar to a solid-state device based on electron conduction, conical pores are shown to have superior performance characteristics compared to traditional cylindrical pores. Such phenomena, however, remain to be exploited for molecular separation. Here we present performance results from silicon membranes created by a new synthesis technique based on interferometric lithography. This method creates millimeter sized planar arrays of uniformly tapered nanopores in silicon with pore diameter 100 nm or smaller, ideally-suited for integration into a multi-scale microfluidic processing system. Molecular transport properties of these devices are compared against state-of-the-art polycarbonate track etched (PCTE) membranes. Mass transfer rates of up to fifteen-fold greater than commercial sieve technology are obtained. Complementary results from molecular dynamics simulations on molecular transport are reported.
Doped ZnO Colloids for Cancer Detection - Bio-Imaging and Cytotoxicity Study
Authors: Wu Linda Y.L. , Loh June , Fu Sheng , Tok Alfred I.Y. , Zeng Xianting , Kwek Leong Chuan , Boey Freddy Y.C. 
Published: September 2009

AbstractWe report the synthesis and surface modification of bio-friendly ZnO based colloids, which have been used for cancer cell detection providing significant advantages on quantum confinement effects, high emission brightness in UV to blue-violate range, non-toxicity and a unique dual color imaging feature. The ZnO nanoparticles were single crystal nanoparticles having spherical shape in size of 1-2 or 4-5 nm depending on the surface capping agents. All the colloidal solutions were stable for 30-45 days. The surface capping is a more effective technique in controlling the nanoparticle size, while dopants are effective in modifying the bandgap and optical properties. Unique dual colour images with blue colour in nucleus and turquoise colour in cytoplasm were obtained using either pure ZnO or Co doped ZnO colloids on human osteosarcoma (Mg-63) cells. The dual colour function is the combined effects of quantum confinement and the bio-compatible surface capping groups. The cytotoxicity study proved no cell proliferation by the nanoparticles up to the concentration of 1000 μg/mL, which is the highest concentration reported so far. Since a dosage of only 50-100μM is enough for the in vivo detection on rate, these ZnO colloids have high potential for use as the detection media for Lab-on-a-Chip devices.
Assessment of Self‐Report Measures for Predicting Population Prevalence of Periodontitis
Authors: Eke Paul I. , Dye Bruce 
Published: September 2009

Background: Self‐report measures have been used successfully for the surveillance of chronic diseases in adult populations. This pilot study assessed the use of self‐report oral health measures for predicting the population prevalence of periodontitis in United States adults.Methods: Data were collected from 456 subjects participating in a 2007 study conducted by the Centers for Disease Control and Prevention. Each subject answered eight predetermined oral health self‐report questions obtained from in‐person interviews and were given a full‐mouth periodontal examination using the National Health and Nutrition Examination Survey protocol. The predictiveness of measures from these self‐report questions was assessed by multivariable logistic regression modeling measuring receiver operating characteristic (ROC) statistics, sensitivity, and specificity.Results: Multivariable modeling incorporating self‐report measures on gum disease, loose teeth, and tooth appearance alone were most useful in predicting the prevalence of severe periodontitis and improved with the addition of demographic and risk factor variables, yielding an ROC value of 0.93, sensitivity of 54.6%, and specificity of 98% at the observed 4.8% prevalence of disease. Scaling and root planing treatments, loose teeth, and the use of mouthwash, combined with demographic and risk factor covariates, were moderately useful in predicting total periodontitis.Conclusions: Multivariable modeling of specific self‐report oral health measures is promising for predicting the population prevalence of severe periodontitis, confirming earlier assessments from a national survey. These results justify further assessments of self‐report oral health measures for use in the surveillance of periodontitis in the adult United States population.