bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture Mechanisms of Bone: A Comparative Study between Antler and Bovine Femur
Authors: Chen P.Y. , Sheppard F.A. , Curiel J.M. , McKittrick J. 
Published: June 2009

ABSTRACTIn this study, fracture toughness of North American elk (Cervus elaphus canadensis) antler and bovine femur were measured using four-point bending tests on single-edge notched compact samples (ASTM C1421). Tests were conducted on crack growth directions longitudinal and transverse to the long axis of antler and bone in both dry and hydrated conditions to study the effects of fiber orientation and hydration. Fracture toughness results in the transverse orientation were much higher than that in the longitudinal orientation and increased with degree of hydration for both antler and bovine femur. The fracture toughness of antler was ∼ 50% higher than that of bovine femur. The highest fracture toughness value was obtained from the hydrated antler in the transverse orientation, which reached 10.31 MPa·m1/2 compared to that measured from bovine femur, which was 6.35 MPa·m1/2. The crack propagation and fracture surface were characterized using scanning electron microscopy. Toughening mechanisms, including crack deflection by osteons, uncracked ligament bridging, and microcracks formation, are observed and discussed. Comparisons between antler and bone are made.
Mapping the Micromechanical Properties of Cryo-sectioned Aortic Tissue with Scanning Acoustic Microscopy
Authors: Akhtar Riaz , Sherratt Michael J. , Watson Rachel E.B. , Kundu Tribikram , Derby Brian 
Published: June 2009

ABSTRACTAlthough the gross mechanical properties of ageing tissues have been extensively documented, biological tissues are highly heterogeneous and little is known concerning the variation of micro-mechanical properties within tissues. Here, we use Scanning Acoustic Microscopy (SAM) to map the acoustic wave speed (a measure of stiffness) as a function of distance from the outer adventitial layer of cryo-sectioned ferret aorta. With a 400 MHz lens, the images of the aorta samples matched those obtained following chemical fixation and staining of sections which were viewed with fluorescence microscopy. Quantitative analysis was conducted with a frequency scanning or V(f) technique by imaging the tissue from 960 MHz to 1.1 GHz. Undulating acoustic wave speed (stiffness) distributions corresponded with elastic fibre locations in the tissue; there was a decrease in wave speed of around 40 ms-1from the adventitia (outer layer) to the intima (innermost).
Bone-Bonding Ability of Anodized Titanium Plate Loaded With Hydroxyapatite Particles
Authors: Iwasaki Mitsunobu , Kudo Kohki , Shimada Kazuki , Matsuzaki Kohji , Hamanishi Chiaki 
Published: June 2009

ABSTRACTSubmicron-sized hydroxyapatite (HAp) particles were loaded on the titanium plate by anodic oxidation over spark discharge voltage in HAp-containing bath. The biocompatibility and bioactivity were drastically improved by HAp deposition on the anodic oxide films. The affinity with living bone was the following order: anodized titanium plate with HAp > anodized titanium plate ≫ titanium. Bone-bonding strength between HAp-loaded titanium plate and living bone after 4 weeks' implant was much higher than that of anodized titanium plate.
Local Release of Basic Fibroblast Growth Factor (bFGF) through Silica Nanoparticles-laden Biomimic Matrix
Authors: Zhang Jin , Gardiner Richard B. , Mumin Abdul , Harris Richard 
Published: June 2009

ABSTRACTBasic fibroblast growth factor (bFGF), a protein, plays a key role in wound healing and blood vessel regeneration. However, most negative effectsin vivo, orin vitroresult from the over dosage of bFGF. Furthermore, it needs to keep the bFGF from protein denaturant. Thus, this study aims to develop a new delivery system based on silica nanoparticles (SiO2NPs) dispersed in collagen patch for delivery of the bFGF in a local and prolonged manner. In this research, SiO2NPs are used to encapsulate bFGF through a modified water-in-oil micro-emulsion. The bFGF-loaded nanoparticles afterwards are dispersed in the collagen-based matrix through a EDC cross-linking step. Thein vitrorelease kinetics of SiO2 NPs - encapsulated bFGF with and without collagen matrix have been monitored through ELISA. In addition, the cytotoxicity of SiO2NPs is investigated by studying the viability of Human Umbilical Vein Endothelial Cells (HUVEC) under the different concentrations of SiO2NPs. It has found the average diameter (d) for SiO2NPs encapsulating bFGF is 45 ± 8 nm with a loading efficiency of 72.5±3%. The maximum concentration of bFGF locally released from SiO2NPs impregnated collagen matrix can be monitored after 30 days, while bFGF released from SiO2NPs can be detected in 20 days. The further prolonged releasing after the nanoparticle-encapsulated bFGF laden collagen matrix is possibly due to the interaction between the nanoparticles and collagen matrix. In addition, the biocompatibility of the SiO2NP has been investigated. We found that SiO2NPs at the concentration of 50 μg/ml can still keep the cell alive. The results indicate that the nanoparticle-laden collagen matrix can locally deliver growth factor in a prolonged manner. This new delivery system may benefit to blood vessel regeneration and potentiate greater angiogenesis.
Optical stability of small-molecule thin-films determined by Photothermal Deflection Spectroscopy
Authors: Stella Marco , Della Pirriera Monica Beatriz , Puigdollers Joaquim , Bertomeu Joan , Voz Cristobal , Andreu Jordi , Alcubilla Ramon 
Published: June 2009

AbstractIn this paper the optical absorption properties of n-type C60and PTCDA, and p-type CuPc small molecule semiconductors are investigated by optical transmission and Photothermal Deflection Spectroscopy (PDS). The results show the usual absorption bands related to HOMO-LUMO transitions in the high absorption region of the transmission spectra. PDS measurements also evidences exponential absorption shoulders with different characteristic energies. In addition, broad bands in the low absorption level are observed for C60and PTCDA thin-films. These bands have been attributed to contamination due to air exposure. In order to get deeper understanding of the degradation mechanisms single and co-evaporated thin-films have been characterized by PDS. The dependence of the optical coefficient on exposure to light and air have been studied and correlated to the structural properties of the films (as measured by X-Ray Diffraction Spectroscopy). The results show that CuPc and PTCDA are quite stable against light and air exposure, while C60shows important changes in its absorption coefficient. The bulk heterojunctions show stability in agreement with what observed for single layers, since the absorption coefficient of CuPc:PTCDA is almost not altered after the degradation treatments, while CuPc:C60shows changes for low energy values.
Interaction of Hf Precursor with H2O-terminated Si(001): First Principles Study
Authors: Kim Dae-Hyun , Kim Dae-Hee , Seo Hwa-Il , Kim Yeong-Cheol 
Published: June 2009

AbstractWe investigated the reaction of HfCl4 molecules with a H2O terminated Si (001)-2×1 surface using density functional theory to understand the initial stage of atomic layer deposition (ALD) of HfO2. Half monolayer of H2O molecules were adsorbed on the buckled-down Si atoms of the Si dimers of the Si (001)-2×1 surface below the dissociation temperature of H2O and were dissociated into H and OH at room temperature. This process could make uniform and well-aligned −H and −OH’s on the Si (001) substrate. The reaction of a HfCl4 molecule was more favorable with -OH than -H. The reaction of the HfCl4 molecule with the -OH generated a HCl molecule, and the remaining HfCl3 was attached to the O atom. The first reaction of the HfCl4 molecule with −OH produced 0.21 eV energy benefit. The reaction of the second HfCl4 molecule with the most adjacent −OH of the first one produced 0.28 eV energy benefit. The third and fourth molecules showed same tendency with the first and second ones. The energy differences of the fifth and sixth HfCl4 reactions were -0.01 eV, 0.06 eV, respectively. Therefore, we found that the saturation Hf coverage was approximately 5/8 of the available −OH's, which was 2.08 × 1014 Hf/cm2. The result was well-matched with the experimental study of other group.
Electrical Resistance and Structural Changes on Crystallizaiton Process of Amorphous Ge-Te Thin Films
Authors: Saito Yuta , Sutou Yuji , Koike Junichi 
Published: June 2009

AbstractGeTe-Sb2Te3 pseudobinary compounds are attracting considerable attention as phase change materials for optical disk and phase change random access memory (PRAM). In these compounds, Ge2Sb2Te5 (GST) has been used for an optical disk memory such as DVD-RAM because the crystallization by laser beam heating is very fast (∼20ns). Recently, the GST has been much considered as material for PRAM and, therefore, the electrical resistance change due to crystallization and the phase change by applying an electrical current have been widely investigated. On the other hand, although GeTe compound has been suggested as the phase change material for the optical disk by Chen et al in 1986, the study focusing on the phase change material for PRAM is limited. Since GeTe is known to show the phenomenon of electrical switching, this compound has a potential of PRAM. In this study, the electrical resistance and crystalline structural changes on crystallization process in Ge-Te thin films were investigated.Films of amorphous Ge100–xTex (x : 46-94) with 200 nm thickness were deposited by sputtering of GeTe alloy target or co-sputtering of GeTe and Te targets on SiO2/Si substrates. In-situ electrical resistance measurements during heating process of these films were performed by two point probe method in a heating rate of 2∼50°C/min. X-ray diffraction (XRD) analysis was employed for the structural identification of thin films for 10-60° in 2′ using X-ray diffractometer with Cu-K. Transmission electron microscope (TEM) analysis was carried out to investigate the microstructure and to identify crystalline structure. The compositions of these films were confirmed by energy dispersive X-ray spectroscopy (EDS) attached TEM.All as-deposited Ge-Te films were confirmed amorphous by XRD and TEM. From the in-situ electrical resistance measurements, it is found that resistance change with crystallization process depends on the composition and the stoichiometric GeTe compound shows abrupt electrical resistance change at around 190 °C. The crystallization temperature of GeTe was higher than that of GST and resistance difference between the amorphous and the crystal was also larger. While the electrical resistance of GST film gradually decreased with increasing temperature after the crystallization at around 160 °C, that of GeTe film showed small temperature dependence after crystallization. It was found by X-ray measurement observation that the amorphous GeTe compound film crystallized first into a cubic state, and then into a stable rhombohedral state by further heating. The crystallization kinetics of Ge-Te thin films will be also presented.
Opto-electrical characterization and X-ray Mapping of large-volume cadmium zinc telluride radiation detectors
Authors: Yang Ge , Bolotnik Aleksey E , Camarda Giuseppe , Cui Yonggang , Hossain Anwar , Yao Walter , Kim Ki Hyun , James Ralph 
Published: June 2009

AbstractLarge-volume cadmium zinc telluride (CZT) radiation detectors would greatly improve radiation detection capabilities and, therefore, attract extensive scientific and commercial interests. CZT crystals with volumes as large as hundreds of centimeters can be achieved today due to improvements in the crystal growth technology. However, the poor performance of large-volume CZT detectors is still a challenging problem affecting the commercialization of CZT detectors and imaging arrays. We have employed Pockels effect measurements and synchrotron X-ray mapping techniques to investigate the performance-limiting factors for large-volume CZT detectors. Experimental results with the above characterization methods reveal the non-uniform distribution of internal electric field of large-volume CZT detectors, which help us to better understand the responsible mechanism for the insufficient carrier collection in large-volume CZT detectors.
Copper Sulfide Assisted Recrystallization of Cu-poor CuInS2 Observed in-situ by Polychromatic X-ray Diffraction
Authors: Rodriguez-Alvarez Humberto , Mainz R. , Weber A. , Marsen B. , Schock H.W. 
Published: June 2009

AbstractThe microstructural changes during heating of bi-layers of Cu-poor CuInS2 and CuS under different sulfur excess conditions were studied. This was done by means of energy dispersive X-ray diffraction of polychromatic synchrotron radiation in a vacuum setup where the sulfur pressure conditions can be controlled. Understood as the formation of a new microstructure, the recrystallization of the Cu-poor CuInS2 phase was characterized by a change in the reflection profile (from Cauchy-type to Gauss-type), the reduction of the breadth and a subsequent normalized-intensity increase of the 112 reflection. The Cauchy component of the breadth was used to monitor the recrystallization under different sulfur and heating rate conditions. The main results are: a) Cu availability for the consumption of the CuIn5S8 phase is a pre-requisite for recrystallization, b) in presence of the Cu2-xS phase, increased sulfur pressure enhances recrystallization.
Comparison of ZnS-based Buffer Layers by Chemical Bath Deposition and Atomic Layer Deposition
Authors: Platzer-Bjöerkman Charlotte , Uhl Alexander 
Published: June 2009

AbstractIn this work we compare ZnS-based buffer layers prepared by atomic layer deposition, ALD, and chemical bath deposition, CBD. Both material and device properties are compared. CBD buffer layers are amorphous with a Zn(OH,S) composition while ALD buffer layers used in devices are crystalline with a Zn(O,OH,S) composition. Devices with ALD buffer layers are stable while for CBD, large lightsoaking effects are seen. Stable devices with CBD buffer layers are obtained by including an ALD-(Zn,Mg)O layer on top of the CBD layer.
Influence of the Cu Content on Structural and Vibrational Properties in Polycrystalline CuGaSe2 Thin Films
Authors: Witte Wolfram , Kniese Robert , Powalla Michael 
Published: June 2009

AbstractWe studied CuGaSe2 (CGS) thin films with different Cu contents by means of X-ray diffraction (XRD) and micro-Raman spectroscopy. The CGS absorbers were deposited by co-evaporation on Mo/glass substrates. We found a clear shift of the CGS Raman mode frequencies to lower values with increasing Cu/Ga ratio. This is in direct correlation with the increasing lattice constants a and c extracted from XRD patterns. Influence of stress on the obtained results can be neglected, because very small stress values below 50 MPa were determined with the sin2Ψ method.
On the Thermoelectric Potential of Inverse Clathrates
Authors: Falmbigl Matthias , Rogl Peter F , Bauer Ernst , Kriegisch Martin , Müeller Herbert , Paschen Silke 
Published: June 2009

AbstractIn the context of a general survey on the thermoelectric potential of cationic clathrates, formation, crystal chemistry and physical properties were investigated for novel inverse clathrates deriving from Sn19.3Cu4.7P22I8. Substitution of Cu by Zn and Sn by Ni was attempted to bring down electrical resistivity and lower thermal conductivity. Materials were synthesized by mechanical alloying using a ball mill and hot pressing. Structural investigations for all specimens confirm isotypism with the cubic primitive clathrate type I structure (lattice parameters a = ˜1.1 nm and space group type Pm-3n). Studies of transport properties evidence holes as the majority charge carriers. Thermal expansion data, measured in a capacitance dilatometer from 4 to 300 K on Sn19.3Cu1.7Zn3P19.92.1I8, compare well with literature data available for Sn24P19.62.4Br8and for an anionic type I clathrate Ba8Zn8Ge38. From the rather complex crystal structure including split atom sites and lattice defects thermal conductivity in inverse clathrates is generally low. Following Zintl rules rather closely inverse clathrates tend to be semiconductors with attractive Seebeck coefficients. Thus for thermoelectric applications the main activity will have to focus on achieving low electrical resistivity in a compromise with still sufficiently high Seebeck coefficients.
Effect of Morphology of ZnO Nanowire Arrays on Interfacial Shear Strength in Carbon Fiber Composites
Authors: Galan Ulises , Ehlert Gregory , Lin Yirong , Sodano Henry Angelo 
Published: June 2009

AbstractZnO nanowire arrays are grown on carbon fiber to enhance the interface strength of a polymer matrix composite without degrading the base fiber and in-plane strength of the composite. The morphology of the nanowire array is controlled during growth to create nanowires with different aspect ratios to elucidate the structure-property relations of the interphase. Nanowires are shown to double the composite interfacial shear strength at an intermediate nanowire length, indicating that an optimal point exists and the interface can be engineered to maximize the interfacial enhancement. Furthermore, the observed effect of the morphology on interface strength indicates that the bond between the ZnO nanowire array and the carbon fiber is quite strong, more than twice as strong as the interaction between the matrix and control fiber.
Development of a Chemiresistor Sensor for Polypropylene Degradation Products
Authors: Dirk Shawn M. , Sawyer Patricia S. , Bernstein Robert , Hochrein James M. , Washburn Cody M. , Howell Stephen W. , Graf Darin C. 
Published: June 2009

AbstractThis paper presents the development of a sensor to detect the oxidative and radiation induced degradation of polypropylene. Recently we have examined the use of crosslinked assemblies of nanoparticles as a chemiresistor-type sensor for the degradation products. We have developed a simple method that uses a siloxane matrix to fabricate a chemiresistor-type sensor that minimizes the swelling transduction mechanism while optimizing the change in dielectric response. These sensors were exposed with the use of a gas chromatography system to three previously identified polypropylene degradation products including 4-methyl-2-pentanone, acetone, and 2-pentanone. The limits of detection 210 ppb for 4-methy-2-pentanone, 575 ppb for 2-pentanone, and the LoD was unable to be determined for acetone due to incomplete separation from the carbon disulfide carrier.
Investigation of Characteristics of Multi-Function ZnO Thin Film Deposited with Various Argon and Oxygen Ratios
Authors: Wu Jong-Shin , Hsu Che-Wei , Cheng Tsung-Chieh , Yang Chun-Hui , Shen Yi-Ling , Wu Sheng-Yao , Huang Wen-Hsien 
Published: June 2009

AbstractThe ZnO thin film was successfully deposited on a glass substrate at RT by a RF reactive magnetron sputtering method. Structural, chemical, optical, and hydrophilic/hydrophobic properties are measured by using a surface profilometer, an x-ray diffractometry (XRD), an x-ray photoelectron spectroscopy (XPS), a UV-VIS spectrophotometer, and a contact angle system, respectively. Results show that the deposition rate decreases with increasing O2/(Ar+O2) ratio. Otherwise, the best stoichiometric and quality of ZnO thin film was observed at 0.30 of O2/(Ar+O2) ratio by the smallest FWHM and the strong O-Zn bonds. Regardless of O2/(Ar+O2) ratio effect or thickness effect, high transmittance (> 86%) in the visible region is observed, while the UV-shielding characteristics depend upon both the magnitude of film thickness. The film thickness plays a more prominent role in controlling optical properties, especially in the UV-shielding characteristics, than the O2/(Ar+O2) ratio. However, the hydrophobic characteristics can be obtained when the glass coating with ZnO thin films. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, has good UV-shielding characteristics, and possesses highly hydrophobic characteristics (self-clean capability), which is highly suitable for applications in the glass industries.
A Single-Step Route Towards Large-Scale Deposition of Nanocomposite Thin Films Using Preformed Gold Nanoparticles
Authors: Wang Weiliang , Cassar Kevin , Sheard Steve , Dobson Peter , Hurst Simon , Bishop Peter , Parkin Ivan 
Published: June 2009

AbstractWe have been developing noble metal nanoparticles and nanocomposites for large scale application to glass surfaces. The novel functionality of the nanocomposites is attributed to the properties of both the metal nanoparticles and host matrix. Here a single-process route to nanocomposite thin films by spray deposition technique has been investigated. Preformed gold nanoparticles have been incorporated into several different transition metal oxides (TiO2, SnO2, ZnO). The nanocomposite films showed intense coloration due to the surface plasmon resonance effects of gold nanoparticles embedded in the host matrix. The gold nanoparticles were found well embedded into the host metal oxides homogeneously. This film deposition method can easily be scaled up and is compatible with current industrial on-line processes.
The Nature and Characterization of Nanoparticles
Authors: Kohli Rajiv 
Published: June 2009

AbstractNanosize particles are of fundamental and practical interest for developing advanced materials and devices and micro and nanostructures. As feature sizes shrink, nanoparticle contamination is also becoming increasingly important to achieve and maintain high product yields. In order to employ appropriate material and product development strategies, or institute preventive assembly and remediation strategies to control nanoparticle contamination, it is essential to understand the nature of nanoparticles and to characterize these particles. Particles in the size range 0.1 nm to 100 nm present unique challenges and opportunities for their imaging and characterization. Critical information for this purpose is the number and size of the particles, their morphology, and their physical and chemical structure. Because of this importance, many advances and new developments have been made in qualitative and quantitative characterization techniques for particles in this size range, including neutron holography, three dimensional atom probe imaging, ultrafast microscopy and crystallography, magnetic resonance force microscopy, and high-resolution x-ray crystallography of non-crystalline structures. It is now possible to completely characterize nanoparticles from 0.1 nm to 100 nm size. A brief review of the nature of nanoparticles is presented and recent developments in selected characterization techniques are described.
Hydrophobic Metallic Nanorods coated with Teflon Nanopatches by Glancing Angle Deposition
Authors: Khudhayer Wisam J , Sharma Rajesh , Karabacak Tansel 
Published: June 2009

AbstractIntroducing a hydrophobic property to vertically aligned hydrophilic metallic nanorods was investigated experimentally and theoretically. First, platinum nanorod arrays were deposited on flat silicon substrates using a sputter Glancing Angle Deposition Technique (GLAD). Then a thin layer of Teflon (nanopatches) was partially deposited on the tips of platinum nanorod at a glancing angle of  = 85° as well as at normal incidence ( = 0°) for different deposition times. We show that GLAD technique is capable of depositing ultrathin isolated Teflon nanopatches on selective regions of nanorod arrays due to the shadowing effect during GLAD. Contact angle measurements on Pt/Teflon nano-composite have shown contact angle values as high as 138°, indicating a significant increase in the hydrophobicity of originally hydrophilic Pt nanostructures. Finally, a 2D simplified wetting model utilizing Cassie and Baxter theory of heterogeneous surfaces has been developed to explain the wetting behavior of Pt/Teflon nanocomposite.