bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Calcium Phosphate Films Prepared by RF Magnetron Sputtering
Authors: Narushima Takayuki , Ueda Kyosuke , Goto Takashi , Katsube Tomoyuki , Kawamura Hiroshi , Ouchi Chiaki , Iguchi Yasutaka 
Published: April 2011

ABSTRACTCalcium phosphate films were prepared on commercially pure titanium (CP-Ti) substrates by RF magnetron sputtering using β-tricalcium phosphate targets. XRD and FTIR analyses showed that the films consisted of amorphous calcium phosphate and oxyapatite phases. The (002) preferred orientation of the oxyapatite phase was observed depending on the oxygen gas concentration in the sputtering gas. The surface reactions of the calcium phosphate films were investigated in Hanks' solution and PBS(-). Apatite crystallites were detected on the films after immersion for 7 days. An active surface reaction was observed on the amorphous calcium phosphate films during immersion in PBS(-). The CP-Ti plates coated with the calcium phosphate films were placed on the mandible of male Japanese white rabbits. These results suggest that the calcium phosphate coating improves the biocompatibility of titanium implants with bone.
Transformation of Helically Structured Nanofibers into Linearly Oriented Nanofibers
Authors: Kim Seon Jeong , Park S. J. , Yoon S. K. , Kim M. S. , Gu B. K. , Kim I. Y. , Kim S. I. , Kim S. J. 
Published: April 2011

ABSTRACTHelical structures have been fabricated from a solution of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) in water and ethanol by the whipping instability of a jet in a conventional electrospinning system. The simple modification of the electrospinning system involved introducing two parallel subelectrodes, which enabled the transformation of helical nanofibers into linearly oriented nanofibers due to the tensional forces caused by the modified electric field. This means that the tensional forces caused by the modified electric field had an important effect on linearizing the helical structures. Therefore, a technique using modified electric fields can play a significant role as an intermediary between helical structures and one-dimensional linear structures.
Studies of Bi4−xGdxTi3O12 Bifunctional Material
Authors: Tomar Maharaj S. , Melgarejo Ricardo E. , Singhal Rahúl , Angelats Luis M. , Katiyar Ram S. 
Published: April 2011

ABSTRACTGadolinium-substituted Bi4Ti3O12 (i.e. Bi4−xGdxTi3O12) were synthesized by sol-gel process for different compositions, and thin films were deposited on Pt (Pt/TiO2/SiO2/Si) substrate by spin coating. Post annealed films at 700° C were investigated for their structural properties using x-ray diffraction and Raman spectroscopy indicating solid solution for compositions: x = 0.00, 0.46, 0.56, and 0.85 where Bi ion is replaced by Gd-ion. Sol-gel derived Pt/Bi4−xGdxTi3O12 film/Pt capacitor structure was tested for dielectric, ferroelectric, and leakage current responses. Films showed ferroelectricity with polarization, Pr = 22 µC/cm2 for composition: x = 0.46. Magnetic response of the powder sample for composition: x = 0.85 was tested using SQUID, which showed superparamagnetic at room temperature and magnetic at 5 K with magnetic coercivity (Hc) = 29 Oe and very small remanance (σr) = 5.4 × 10−4 emu/g.
Self Assembly in Biologically Synthesized Electrospun Electroactive Polymers
Authors: Bishop A. , Gouma P. 
Published: April 2011

ABSTRACTThe processing parameters of polyaniline (PANI) dictate the desired morphology and overall structural stability of the deposited polymer for biological and chemical sensor applications. Electrospun composites of leucoemeraldine based PANI (LEB-PANI) has exhibited effective separation of aggregates inherent in LEB-PANI powder as a result of charge separation induced on the composite matrix during electrospinning. However it appears the encapsulation of biological (enzyme-Urease E.C.3.5.1.5) in the electrospun matrix intensifies the self assembly process. An investigation of the changes in morphology as an effect of electrospinning and enzyme immobilization is discussed.
Influence of Crystallization Condition on Structure of P(VDF-CTFE) Copolymers
Authors: Yang Xin , Li Zhimin , Odum LeVar , Cheng Z.-Y. 
Published: April 2011

ABSTRACTThe influence of the crystallization condition - temperature and time - on the structure of poly (vinylidene fluoride chlorotrifluoroethylene), P(VDF-CTFE), was studied using DSC and XRD. The DSC results of all studied polymers show three peaks. One peak, which is associated with crystallization temperature, represents the appearance of unstable phase in the polymers. Both XRD and DSC data indicate the coexistence of different phases in the polymers, which may be the reason for the high electrostrictive performance obtained in the polymers.
Bulk and Interface Charging Mechanisms in Organic Semiconductor-Gate Dielectric Bilayers
Authors: Katz Howard E. , Huang Cheng , West James 
Published: April 2011

ABSTRACTSince the first reports of charge storage in the gate dielectrics of organic semiconductors, several groups have proposed charge-storing dielectrics that become polarized through varied mechanisms, and have offered various explanations for observed charge storage phenomena. These groups were concerned either with nonvolatile memories as an application, or with controlling hysteresis in conventional OFETs. This manuscript describes measurements of surface charging and OFET threshold voltage shift for a case where charge is clearly stored in the dielectric. The magnitude and stability of the charge storage depend on the hydrophobicity of the dielectric and the charge deposition process. We focus on SiO2 as the dielectric and use a thiophene oligomer or hexadecafluoro-copper phthalocyanineas semiconductor. In one case, the phthalocyanine was inverted from electron- to hole-carrying, enabling a complementary device to be made from a single semiconductor.
Mechanisms of Long-Term Uranium Transport under Oxidizing Conditions
Authors: Murakami Takashi 
Published: April 2011

AbstractUnderstandings of U transport at the Earth’s surface are quite important especially for the disposal of radioactive waste and the remediation of contaminated ground water. We examined long-term U transport in and around the Koongarra U deposit, Australia, which has been subjected to weathering for the past 2 million years. The formation of saléeite [Mg(UO2)2(PO4)2·10H2O] occurred at the rim of apatite [Ca5(PO4)3(F,OH)], where the ground waters had about 200 - 400 ppb U (∼10-7 mol·l-1) and were undersaturated with respect to saléeite. The laboratory experiments using apatite and U-containing solutions and Rutherford backscattering spectrometry of the apatite surface have suggested that a leached layer of about 100 nm thick is formed on dissolving apatite, saléeite is precipitated only in the leached layer by local saturation, and saléeite precipitated is added to the interface between the leached layer and solution. At lower U concentrations (∼10-8 mol·l-1), U occurred as nanocrystals (20-100 nm in size) of uranyl phosphates such as metatorbernite [Cu(UO2)2(PO4)2·8H2O], scattered between and attached firmly to nanocrystals (2-50 nm in size) of goethite and hematite. A possible mechanism is that U, P, and Mg or Cu adsorbed onto ferrihydrite form nanocrystals of uranyl phosphates during crystallization of goethite and hematite from ferrihydrite. The above two mechanisms significantly lower the U concentration in the ground water that flows into the Koongarra creek, 200 m downstream from the ore deposit, where the U concentration is ∼10-10 mol·l-1. We conclude that the two mechanisms of uranyl-phosphate mineralization control the long-term U transport at Koongarra.
Theoretical Studies of Hydrogen and Water Adsorption on Actinide Oxide Surfaces
Authors: Hay P. Jeffrey 
Published: April 2011

AbstractThe adsorption of H2O on UO2 and PuO2 surfaces is studied using density functional theoretical approaches. Periodic slab models are employed to represent the oxide surface in which five layers of the oxide are explicitly treated. For both oxides the dihydroxyl form corresponding to dissociated H2O is more stable than the molecularly adsorbed H2O on the (111) and (110) surfaces. Adsorption of H2 on PuO2 and Pu2O3 is also investigated where stable forms corresponding to dissociated H atoms are found.
Relationships between the crystal chemistry and magetic properties of Np5+ sulfates
Authors: Forbes Tori Z. , Burns Peter C. , Soderholm L. , Skanthakumar S. 
Published: April 2011

AbstractNp5+ sulfate compounds were synthesized using hydrothermal methods and their structures were determined using single crystal X-ray diffraction. Several compounds were found to contain cation-cation interactions between the Np polyhedra. Magnetic susceptibility measurements of two Np5+ sulfate compounds containing cation-cation interactions exhibit ferromagnetic ordering. The presence of the cation-cation interactions may provide a superexchange pathway through which magnetic interactions can be enhanced.
Evaluation of Electric Potential at Metal-Insulator Interface Using Electron Spectroscopy and Kelvin Probe Techniques
Authors: Yoshitake Michiko 
Published: April 2011

AbstractThe potential of applying photoelectron spectroscopic and Kelvin probe methods for the interface potential evaluation of materials prepared by combinatorial processes is demonstrated. The physical basis for the evaluation of the interface potential by photoelectron spectroscopy is given. Then, the imaging capability of photoelectron spectroscopy is demonstrated using a two-dimensionally patterned specimen. Finally, the examples of interface potential evaluation with photoelectron spectroscopy and Kelvin probe are presented. Through the evaluation of interface potential with this method, it is possible to deduce the energy level diagram across the interface between two materials with different electron properties.
Cathodic Arc Plasma Combinatorial Material Synthesis for Composition Search of New Amorphous Alloy
Authors: Hata Seiichi , Yamauchi Ryusuke , Sakurai Junpei , Shimokohbe Akira 
Published: April 2011

AbstractCombinatorial arc plasma deposition (CAPD) method was used to search for new compositions of thin film amorphous alloys. A cathodic arc plasma gun (APG) was adopted as the deposition source for CAPD. The CAPD setup has three APGs radiating out from the center of a substrate. The APGs shoot pulse-like plasma shots one by one at a specific time interval. The plasma from each APG cathode is guided onto a specific area on a substrate by a magnetic field. Each such area overlaps the adjacent ones. Thus, a compositionally-graded thin film is deposited in the overlap area because of mixing of each deposited thin film from each APG that has a thickness grade. The deposited thin film is separated into 1,089 samples (the size of each is 1×1 mm2) using a grid on the substrate. The samples together are referred to as the thin film library. To demonstrate the capability of CAPD, two thin film libraries were deposited in this study. One is a thin film library of a PdCuSi alloy system, and the other is a MoZrPd system. The compositions and crystallinity of the samples were evaluated on the substrate using EDS and IP-XRD respectively. Analysis of the samples showed a graded composition, and some of the samples were shown to be amorphous in both libraries.
High Throughput Screening of Marine Coatings using Biological Assays
Authors: Stafslien Shane , Chisholm Bret , Christianson David , Daniels Justin , Swain Geoffrey 
Published: April 2011

AbstractA combinatorial workflow for developing organic surface coatings has been developed. The workflow is uniquely designed to prepare and evaluate marine coatings that prevent biofouling on the hulls of ships. A critical component of the workflow is the high throughput screening of settlement and ease of removal of marine organisms from coating surfaces. Methods have been developed to directly and indirectly quantify marine bacterial biofilm growth and retention. Correlations have been developed between these high throughput bioassays and results from ocean testing.
Lessons from Simulation Regarding the Control of Synthetic Self-Assembly
Authors: Douglas Jack F. , Van Workum Kevin 
Published: April 2011

AbstractWe investigate the role of particle potential symmetry on self-assembly by Monte Carlo simulation with the particular view towards synthetically creating structures of prescribed form and function. First, we establish a general tendency for the rotational potential symmetries of the particles to be locally preserved upon self-assembly. Specifically, we find that a dipolar particle potential, having a continuous rotational symmetry about the dipolar axis, gives rise to chain formation, while particles with multipolar potentials (e.g., square quadrupole) having discrete rotational symmetries led to the self-assembly of random surface polymers preserving the rotational symmetries of the particles within these sheet structures. Surprisingly, these changes in self-assembly geometry with the particle potential symmetry are also accompanied by significant changes in the thermodynamic character and in the kinetics of the self-assembly process. Linear chain growth involves a continuous chain growth process in which the chains break and reform readily, while the growth of the two-dimensional polymers only occurs after an ‘initiation’ or ‘nucleation’ time that fluctuates from run to run. We show that the introduction of artificial seeds provides an effective method for controlling the structure and growth kinetics of sheet-like polymers. The significance of these distinct modes of polymerization on the functional character of self-assembly growth is illustrated by constructing an artificial centrosome structure derived from particles having continuous and discrete rotational potential symmetries.
Fluorescence Correlation Spectroscopy Study of TAMRA Diffusion in Poly(vinyl-alcohol) and Ficoll70 Solutions
Authors: Michelman-Ribeiro Ariel , Horkay Ferenc , Nossal Ralph , Boukari Hacene 
Published: April 2011

AbstractWe compare fluorescence correlation spectroscopy (FCS) measurements of the fluorescent nanoparticle, TAMRA, diffusing in non-fluorescent -hence invisible- poly(vinyl-alcohol) (PVA) or Ficoll70 solutions as a function of the polymer concentration, c. We determine changes of the translational diffusion coefficient of TAMRA and fit the data with the universal scaling law (D ∼ exp[−α(c/c*)ν], to extract information about solvent quality. For PVA, we find ν = 0.74, suggesting that water in this case acts as a good solvent, whereas ν = 1.02 in Ficoll70 solutions, indicating theta-like behavior.
Characterizations of Multiphase Biogenic Polymer Blends from Poly(L-lactide) and Poly(methyl methacrylate)
Authors: Le Kim-Phuong Nguyen , Lehman Richard Long , VanNess Kenneth , Idol James D 
Published: April 2011

AbstractMelt processing of binary immiscible polymer systems has been a focus of our group as an economical and scalable route to achieve synergistic or superior mechanical properties at and around the co-continuous region without the need of compatibilization. System of poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was selected to target bio-related applications, including bone fillers and scaffolds, where the biodegradability of PLLA will enable the integration of native tissue into the material over time. Tunable properties such as morphology, interconnectivity, resorbability and interfacial bonding control the long-term integrity of the new material and influence the interaction and integration of new tissue. Binary blends of PLLA and PMMA has been prepared and characterized over a large range of compositions in which regions of co-continuity are of special interest. Such regions exhibit a well interconnected structure that ensures controlled release of resorbable PLLA. Modulated differential scanning calorimetry (MDSC) detected a broad and unexpected transition between 70 °C and 100 °C. The magnitude of this transition is greatest within co-continuous regions, suggesting the presence of a complex or other derivative of the two primary phases. This complex appears to provide a degree of compatibilization between the phases, thus inducing mechanical property synergism which has been confirmed by flexural and nano-indentation analyses.
Synthesis and luminescence properties of novel ZnO nanostructures: micro and nanospheres, polyhedral cages, tetra-pods, needles, tipped nanorods, nanowires and other “microphone–shaped” structures
Authors: Khan Aurangzeb , Jadwisienczak Wojciech M , Kordesch Martin E 
Published: April 2011

ABSTRACTNovel ZnO nanostructures such as hollow nanospheres, nano-cages, nanoneedles, tetra-pods, nanowires, aligned nanorods and nanotubes are synthesized via thermal evaporation of ZnO and graphite powder mixtures in reduced oxygen atmosphere in the presence of argon and nitrogen flows. The ZnO nanostructures, especially nanospheres, have a unique shape and are hollow inside with walls densely decorated with aligned nanowires. Photoluminescence of synthesized ZnO structures measured at 300 K exhibits a strong near band edge peak at ∼380 nm and deep level green band centered at ∼550 nm. Fabricated ZnO structures can be studied for various applications in optoelectronics and sensors.
Synthesis of ZnO Nanowires by Pulsed Laser Deposition in Furnace
Authors: Jeon Kyung Ah , Son Hyo Jeong , Kim Jong Hoon , Yoo K. H. , Lee Sang Yeol 
Published: April 2011

ABSTRACTZnO nanowires (NWs) were fabricated on Au coated sapphire (0001) substrates by using a pulsed laser deposition (PLD) system in vacuum furnace with a Q-switched Nd:YAG laser. ZnO NWs have various size and shape with a substrate position inside a furnace, and their morphologic construction is reproducible. Scanning electron microscopy (SEM) images indicate that the diameters of ZnO NWs ranged from 100 to 150 nm and the average length was greater than 3 μm. Room-temperature photoluminescence spectra of the NWs show the near band-edge emissions and the deep-level green light emissions. The formation mechanism of the NWs is discussed.
Nitrogen and Fluorine Roles in Visible-Light-Driven Anion-Doped TiO2 Photocatalysis
Authors: Di Li , Ohashi Naoki , Hishita Shunichi , Kolodiazhnyi Taras , Haneda Hajime 
Published: April 2011

ABSTRACTThis paper describes the synthesis of N-doped, F-doped, and N-F-codoped TiO2 powders (NTO, FTO, NFTO) by spray pyrolysis (SP). An overall comparative study was carried out on these anion-doped powders in order to elucidate the roles of N and F played in visible-light (Vis)-driven photocatalysis. The comparisons in their characteristics were based on the analysis of UV-Vis, PL, NH3-TPD and ESR spectra. As the results, N-doping into TiO2 resulted in both the improvement of Vis absorption and the creation of surface oxygen vacancies (OVs). F-doping produced several beneficial effects including the creation of surface OVs, the enhancement of surface acidity and the increase of Ti3+ ions. The photocatalytic tests indicated that the NFTO demonstrated the highest Vis activity for decomposition of both acetaldehyde and trichloroethylene. This high activity was ascribed to a synergetic consequence of doped N and F.
EXAFS Study on Nanosized PtRu Catalyst for Direct Methanol Fuel Cell
Authors: Nitani Hiroaki , Ono Takahiro , Honda Yusuke , Koizumi Akiko , Nakagawa Takashi , Yamamoto Takao A. , Daimon Hideo , Kurobe Yukiko 
Published: April 2011

ABSTRACTNano-sized PtRu catalysts supported on carbon nanoparticles were synthesized by a polyol process. The PtRu catalyst prepared at pH=3 indicated higher catalysis for methanol oxidation than one prepared at pH=5.5. The samples were analyzed by techniques of the extended X-ray absorption fine structure (EXAFS), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Their results showed that the pH of the precursor solution during the polyol process affected the substructure of the PtRu nanoparticles. The correlation of the substructure with the catalytic activity was studied.
Atomistic Simulations of Nanoporous Anodic Aluminum Oxide
Authors: Adiga Shashishekar P. , Zapol Peter , Curtiss Larry A 
Published: April 2011

ABSTRACTNanoporous membranes based on anodized aluminum oxide are prepared with atomic level control of pore dimensions and pore wall compositions by atomic layer deposition and are under investigation for use in catalysis. Simulation and modeling help to understand reactivity in confined geometry and to develop rational design of these new materials. In this context, we present results of molecular dynamics simulations of amorphous aluminum oxide surfaces. The surface structure is discussed in terms of density profiles, bond angle distributions and coordination numbers of surface atoms.
Piezoelectric Properties of Lead Zirconate Titanate Films Prepared by Arc Discharged Reactive Ion-Plating Method
Authors: Akamatsu Masahiro , Yasuda Yoshiaki , Tani Masanao , Iijima Takashi 
Published: April 2011

AbstractThis study is about new plasma deposition method fabricating piezoelectric films applied for actuators in MEMS devices.
Extrinsic Contributions to Piezoresponse Force Microscopy
Authors: Peter Frank , Reichenberg Bernd , Rüdiger Andreas , Waser Rainer , Szot Krzysztof 
Published: April 2011

AbstractPiezoresponse force microscopy (PFM) is the method of choice to investigate piezoactivity on a nanometer scale. A careful distinction between intrinsic and extrinsic effects are mandatory, especially when measuring ferroelectric nanostructures. We focus on two omnipresent extrinsic contributions with a substantial impact: firstly adsorbates on the surface of perovsike materials and secondly the dependence of the lateral piezoresponse on the topography. A thorough understanding of these extrinsic contributions is essential in order to avoid ambiguities in the analysis of PFM measurements.
Real Information Recording in Ferroelectric Data Storage Medium with Memory Density of 1 Tbit/inch2
Authors: Tanaka Kenkou , Hiranaga Yoshiomi , Cho Yasuo 
Published: April 2011

AbstractIn this study, a new method to achieve real information recording with a density of 1 Tbit/inch2 in ferroelectric data storage systems is proposed. In this system, data bits were written in the form of the polarization direction of nano domains. Local domain switching was carried out by applying a voltage pulse. A series of test writes revealed that the bit size varied according to the polarization direction of the bits in the immediate environment. Therefore, in order to keep the bit size constant (at 25.6 nm), the pulse amplitude required to create each individual bit was calculated as a function of the polarities of the surrounding data bits. As a result, real information storage at a density of 1 Tbit/inch2 was successfully achieved, with a low bit error rate of 1.8 × 10-2.
Surface Potential Investigation on Nano Domain Formation in Lithium Tantalate Single Crystal
Authors: Katoh Mirai , Cho Yasuo 
Published: April 2011

AbstractThe surface potential distribution following polarization reversal by scanning probe microscopy is examined in order to determine the mechanism of anti-parallel polarization reversal and ring-shaped domain formation in single-crystal lithium tantalate. Lithium vacancy lattice defects are identified as charge-trapping sites, with the resultant surface potential distribution governing the formation of ring-shaped nano-domains. The behavior of this charge injection is shown to be dependent on atmospheric humidity.