bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation of uranium nanoparticles produced via pulsed laser ablation
Authors: Trelenberg Tom , Glade Stephen C , Tobin James G , Felter Thomas E , Hamza Alex V 
Published: April 2011

AbstractAn experimental apparatus designed for the synthesis, via pulsed laser deposition, and analysis of metallic nanoparticles and thin films of plutonium and other actinides was tested on depleted uranium samples. Five nanosecond pulses from a Nd:YAG laser produced films of ∼1600 Å thickness that were deposited showing an angular distribution typical of thermal ablation. The films remained contiguous for many months in vacuum but blistered due to induced tensile stresses several days after exposure to air. The films were allowed to oxidize from the residual water vapor within the chamber (2×10-10 Torr base pressure). The oxidation was monitored by in-situ analysis techniques including x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and scanning tunneling microscopy (STM) and followed Langmuir kinetics.
Combinatorial approach to exploration of a novel fluid oxide flux stable in vacuum for material processing
Authors: Matsumoto Yuji , Koinuma Hideomi , Tsuruta Hirohiko , Takahashi Ryota 
Published: April 2011

AbstractWe explored a new fluid flux stabilized even in the vacuum condition at high temperature by combinatorial pulsed laser deposition (PLD) approach. A small amount of CuO doped in BiOx was found to effectively stabilize BiOx even in 6 Torr O2 at 800°C. The application of this novel Bi-Cu-O flux to the vacuum process lead to the successful fabrication of a single crystal Bi4Ti3O12 film and the establishment of a more reliable process for preparation of an atomically flat LaAlO3(001) substrate.
A Calculation Method of Deposition Profiles in Chemical Vapor Deposition Reactors Using Genetic Algorithms for The Automatic Modeling System of Reaction Mechanisms
Authors: Takahashi Takahiro , Ema Yoshinori 
Published: April 2011

AbstractFast and accurate calculation of the predicted results of Chemical Vapor Depositions (CVD) is very helpful to the high-throughput optimization of the CVD processes. In addition, robustness of the calculation process is important for automation of the optimization process. Therefore, we have developed a novel calculation method, by which robust and accurate calculations along with reduced computing cost were achieved, to reproduce deposition profiles in a macroscopic cavity (macrocavity). Boundary value problems for estimating diffusion-reaction equations by iterations of numerical integrations were changed into problems of finding the linear combinations consisted of a few functions. The coefficients of the linear combinations were optimized by Genetic Algorithms (GA). We could demonstrate the validity of the proposed method using various examples of the reaction mechanisms and conditions.
Analysis of the Structural Specificity of ZrO2Nanoparticles in Pillared Clays by Modeling of the Condensation Process in ZrOCl2*8H2O Solutions
Authors: Mezentseva Natalya , Sadykov Vladislav Aleksandrovich , Avdeev Vasilii Ivanovich , Kuznetsov Vladimir L'vovich 
Published: April 2011

AbstractA combination of quantum-chemical approaches including DFT, semiempirical PM3 and molecular mechanics (force field MM+) methods has been applied for analysis of the structure of polynuclear hydroxocomplexes of Zr in diluted solutions of its oxochloride as precursors of zirconia nanoparticles in zirconia-pillared clays. Relative stability of complexes differing by their size and shape has been estimated.
Adsorption of atomic and molecular oxygen on the SrTiO3(001) surfaces: Computer simulations by means of hybrid density functional calculations and ab initio thermodynamics
Authors: Piskunov Sergei , Zhukovskii Yuri F. , Kotomin Eugene A. , Heifets Eugene , Ellis Donald E. 
Published: April 2011

AbstractAb initio calculations based on density functional theory (DFT) have been used to study the energetics, fully relaxed structure, charge redistribution, and electronic density of states of adsorbed atomic and molecular oxygen on defectless unreconstructed SrO- and TiO2-terminated SrTiO3(001) surfaces. Exchange-correlation functional applied within DFT contains a “hybrid” of the non-local Hartree–Fock exchange, DFT exchange, and generalized gradient approximation correlation functionals. The calculations are performed on periodically repeated systems (two-dimensional slabs) large enough for the adsorbed species to be treated as isolated. We find substantial binding energies of up to 1.8 eV for atomic oxygen adsorption over surface oxygen and of over 2.0 eV at bridge (position between two adjacent surface atoms) sites of both SrO- and TiO2-terminated surface. A range of different adsorption sites and orientations for molecular oxygen have been studied but practically in no case does the adsorption energy exceed 0.1 eV. The stability diagram of surface structures in contact with a gaseous oxygen environment is calculated by means of atomistic thermodynamics. Adsorption of the reactants is found to depend significantly on temperature and partial pressures in the gas phase.
Combinatorial Compounding
Authors: Adams Nico , Moneke Martin , Guelmues Serguel Acikalin , Chenouf Dalil , Rehahn Matthias , Schubert Ulrich S 
Published: April 2011

AbstractThe need for fast and low-cost processes for compound development is obvious when “bespoke” products are required in small quantities. In a typical development workflow, many experiments are needed for the systematic study of the effects of additives and their potential synergistic interactions. This is usually accomplished using the one-variable-at-a-time variational principle. However, if the complexity of the formulation is high, the number of experiments that needs to be conducted soon becomes prohibitive. Therefore, new, but potentially more effective additives are not easily introduced. To address this problem, the plastics processing industry is turning to the notion of combinatorics, which has been shown to accelerate R&D times both in the pharmaceutical industry as well as in other areas of materials science such as catalysis and polymer chemistry.The contribution discusses the development of a combinatorial compounding line, consisting of a production-size twin screw extruder with four gravimetric feeding units for the addition of additives. Furthermore, the development of fast on-line and in-line analytics for compound characterization is discussed.
pH-dependent Gelation of Gastric Mucin
Authors: Bansil Rama , Celli Jonathan , Chasan Benard , Erramilli Shyamsundar , Hong Zhenning , Afdhal Nezam H. , Bhaskar K.Ramakrishnan , Turner Bradley S 
Published: April 2011

AbstractWe discuss the mechanism by which gastric mucin forms a gel at low pH, which serves to protect the stomach from being damaged by the acidic gastric juice that it secretes. Frequency dependence of viscoelastic moduli of pig gastric mucin gels obtained by microscopic dynamic light scattering is presented. Atomic Force Microscopy provides direct visual evidence to indicate that mucin broken into its subunits does not gel at low pH.
Microparticles of Alginate Calcium Gel Modified by Chitosan for Pulsative Delivery Of Rifampicine
Authors: Batyrbekov Erkesh O , Iskakov Rinat , Kombarova Karlygash , Tleumukhambetova Aliya , Zhubanov Bulat 
Published: April 2011

AbstractThe aim of this work is the development of controlled delivery system immobilized by antimicrobial drug rifampicine on the basis of microparticles of alginate calcium gel, modified by natural polymer chitosan. Modified microparticles were obtained by syringed dropwise a solution of rifampicine in solution of sodium alginate was into a mixed solution of chitosan in calcium chloride. The obtained modified alginate microparticles were contained immobilized rifampicine and a surface layer of chitosan. Effects of chithosan concentration and exposure duration on the thickness of polymer coating were determined. For the determination of surface thickness a red congo dye has been used able to form a complex with chitosan. It has been established that with an increase in the concentration of a polymer from 0,3 up to 1,5 mass % the thickness of the modified layer increases from 5 up to 60 mcm, and an increase of the time of gel exposition in a 2,5% solution of chitosan from 30 min to 24 h results in an increase in thickness of a layer from 5 up to 20 mcm respectively. When studying an influence of pH of the medium upon an interaction of alginate and chitosan it was been observed a formation of a polyelectrolyte complex between a chitosan polycation and an alginate polyanion stabilized by ionic bonds. The release of rifampicine from the modified alginate gel particles into a physiological solution with different thickness of a chitosan coating were studied. It was shown that the characteristic maximums on the curve of release observe after 10, 30, 90 and 120 min for the samples without the coating and with the coating thickness of 55, 100 and 150 mcm respectively. The data obtained shown a possibility of the regulation of the rate of rifampicine relase from the modified alginate particles by way of alternation of thickness of the chitosan coating.
Segmented Polyurethane/Collagen Blends for Biomedical Application
Authors: Batyrbekov Erkesh O , Iskakov Rinat , Esenalina Gulsharat , Kurashev Aman , Kim Maria , Zhubanov Bulat 
Published: April 2011

AbstractIn the present study the preparation of biomedical devices and some biomedical application of implantable devices based on segmented polyurethane (SPU)/collagen blends have been described. SPU with different content of hard and soft segments were synthesised by a two-step polymerization using a number of polyethylene and propylene glycols and tolylene diisocyanate.The successful biomedical application of SPU/collagen blends as biomaterials at some fields of medicine has been shown. These blends were used for the fabrication of artificial esophageal prostheses for treatment of injures and diseases of esophagus such as chemical burns, cicatrical structures, total stenosis in children when standard technique of surgical bypass of the nonfunctioning esophagus can not be used. The SPU/collagen blends containing anticancer agents were used for treatment of sarcoma of the orbit. It was established that the anticancer effect against Rhabdomiosarcoma of implanted blends prolongs 17-20 days and the toxic effects decrease due to reduce a total therapeutic dose from 2,0 mg/kg to 1,4 mg/kg.Microparticles of SPU with diameter 200-500 microns were prepared with water-toluene interface emulsion polycondensation of toluene-2,4-diisocyanate and poly(ethylene glycol) of various molecular weight 400-2000. The current procedure allows to develop a series of microcapsulated drug delivery forms for respiratory therapeutic use. A method of exterior nose correction using a biocompatible SPU/collagen blend has been developed. The successful application of polyurethane films for reconstruction of the bridge and septum of nose in 15 patients was described.
Compositionally Modified Hydroxyapatite Nanocrystals for Polymer/Ceramic Scaffold Applications
Authors: Stanishevsky Andrei , Chinoda Peserai , Chowdhury Shafiul , Thomas Vinoy , Catledge Aaron , Dean Derrick 
Published: April 2011

AbstractThe polymer/bioceramic composite materials attract much attention for the development of bioresorbable implants and tissue engineering scaffolds. Hydroxyapatite (HA) is the most commonly used bioceramic material due to its similarity to the major mineral component of the hard tissue. We synthesized carbonated and Mg-substituted HA nanocrystals with various concentrations of CO32− and Mg2+ ions by chemical precipitation in the range of the process temperatures from 25 °C to 100 °C.The HA nanocrystals were mixed with several polymeric materials (PCL, PLA, PVA, collagen) to fabricate bulk and nanofiber polymer/HA nanoparticle composites with the HA loading up to 80 % by weight. The HA nanocrystals and polymer/HA composites were characterized by X-ray diffraction, FT-IR spectroscopy, scanning electron and atomic force microscopy. Mechanical properties of the composites were investigated using nanoindentation technique.
Biomimetic Recognitive Polymer Networks for Ocular Delivery of Anti-Histamines
Authors: Venkatesh Siddarth , Sizemore Stephen P , Byrne Mark E. 
Published: April 2011

AbstractEnhanced drug partitioning in hydrogels can be achieved by configurational biomimetic imprinting (CBIP) techniques which involve the formation of pre-polymerization complexes between template molecules and functional monomers with specific chemical structures designed to interact with the template via non-covalent chemistry. This new class of recognitive intelligent materials is designed by incorporating motifs with structural and molecular homology to biological receptors and has a strong potential to impact the administration of a number of ocular therapies.This work addresses the unmet need for the controlled release of histamine antagonists such as ketotifen fumarate on the surface of the eye to treat allergic conjunctivitis. Mast cell and eosinophil degranulation occurs due to the IL-4 driven TH2 cell response to allergens and the subsequent IgE secretion. This prompts the release of inflammatory mediators such as histamine, which binds to the H1-receptors. Pharmacological downregulation is possible by the local delivery of H1-antihistamines, resulting in decreased vascular permeability, bronchodilation, and exudation of effector cells.Treatment options for seasonal and perennial allergic conjunctivitis primarily consist of oral antihistamines (which provide only partial and delayed relief with potential systemic side effects) and topical treatments. Since ocular bioavailability of topical drugs is very poor (typically less than 7% is absorbed by the eye), a high dosage is needed which prohibits contact lens use. Controlling and tailoring the release of anti-histamines via novel recognitive contact lenses with significantly enhanced partitioning can solve these problems with increased bioavailability, less irritation to ocular tissue, and reduced ocular and systemic side effects. Controlled release by conventional soft contact lenses typically does not work due to a lack of sufficient drug loading.Inspired by Nature, we have successfully synthesized and characterized recognitive networks for H1 antihistamines by choosing monomers on the basis of the non-covalent interactions found in histamine docking sites. This leads to significantly enhanced drug loading and tailorable controlled release of a therapeutically viable dosage of drug.
Modifying the Properties of Collagen Scaffolds with Microfluidics
Authors: Shreiber David I , Sundararaghavan Harini G , Song Minjung , Munikoti Vikram , Uhrich Kathryn E 
Published: April 2011

AbstractIt is now well accepted that the mechanical properties and cell adhesion profile of 2D and 3D extracellular matrix molecules combine to dictate cellular fate processes, such as differentiation, migration, proliferation, and apoptosis, through a process generally known as 'mechanotransduction', or the conversion of mechanical signals into a cellular response. The stiffness and adhesion density combine to affect the force balance that exists between an adherent cell and the surrounding substrate. We have established BioMEMS, microfluidic technology to alter the mechanical properties and cell adhesion profile of collagen scaffolds. Using soft lithography, we fabricate elastomeric networks that serve as conduits for the controlled mixing of type I collagen solutions. Our technology enables us to generate reproducible, controlled homogeneous and inhomogeneous microenvironments for 3D cell culture, assays of cell behavior in 3D, and the development of bioartificial tissue equivalents for regenerative and reparative therapies. The adhesivity of collagen is modulated by covalently grafting peptides (such as RGD) or proteins (such as albumin) to soluble collagen molecules with 1- ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC), a hetero-bifunctional coupling agent. EDC activates the carboxylic group of collagen and forms an amine bond with the grafting molecule. The grafted collagen self-assembles into a fibrillar gel at physiological temperature and pH with no measurable changes in rheological properties compared to controls. A solution of peptide-grafted collagen is then mixed in microfluidic networks with unaltered collagen to form controlled gradients or other patterns of the two solutions, which immobilize upon self-assembly. Separately or in the same network, the mechanical properties of the collagen gel can be altered regionally by the microfluidic delivery a solution of a cell-tolerated crosslinking agent. We use genipin, which has the unique property of generating crosslinks that autofluoresce. The intensity of the fluorescence correlates with the degree of crosslinking (and thus the mechanical properties) enabling us to monitor and measure changes in mechanical properties dynamically and non-invasively. Lastly, though it requires constant delivery or recirculation, the same networks can be used to impose gradients of soluble factors, such as growth factors and cytokines. Thus, we have developed a platform to examine the response of cells to simultaneous chemotactic, haptotactic, and durotactic gradients in a 3D environment. We are employing this technology to examine the response of neural cells to gradients of biomaterial properties to optimize cues for spinal cord regeneration.
Ultrafast Orientational Dynamics of Nanoconfined Benzene
Authors: Zhu Xiang , Farrer Richard , Fourkas John 
Published: April 2011

AbstractOptical Kerr effect spectroscopy has been used to study the orientational dynamics of benzene and benzene-d6 confined in nanoporous sol-gel glasses. Orientational diffusion was found to be inhibited considerably in confinement due to the strong wetting of benzene on silica. The orientational dynamics of benzene-d6 were found to be affected less than those of benzene, which is in agreement with the somewhat larger contact angle of benzene-d6 on silica. Comparison of our results to Raman data for confined benzene-d6 suggests that this liquid is considerably more organized at the pore surfaces than in the bulk.
Non-lithographic Nanofabrication Using Porous Alumina Membranes
Authors: Ram K. Bhargavan , Tian L. , Wu Z , Menon Latika 
Published: April 2011

ABSTRACTWe describe a fabrication method to prepare highly ordered Si nanopore arrays. A nanoporous alumina template of thickness ∼1μm is prepared by means of anodization of an aluminum film. The template has a highly ordered hexagonal array of pores of diameter ∼50nm. The template is detached from the aluminum layer and placed on a Si substrate. The nanoporous pattern is transferred onto silicon substrate by means of a dry plasma etch process. This produces an array of nanopores in silicon with a diameter of ∼50nm and depth of ∼300nm. We have used such an array to prepare Fe nanopillars inside the pores by means of thermal evaporation. Magnetization versus applied magnetic field measurements for the Fe nanoarrays, demonstrate large perpendicular anisotropy typical of high aspect ratio magnetic nanopillars. The value of coercivity is about 500Oe in the perpendicular direction and 40Oe in the parallel direction.
Nanoscale characterization of Pd/TiO2 catalysts and Ag/TiO2 catalysts by electron holography
Authors: Ichikawa Satoshi , Akita Tomoki , Okazaki Kazuyuki , Tanaka Koji , Kohyama Masanori 
Published: April 2011

ABSTRACTCatalytic properties of noble metal catalysts are often caused by their nanostructures and the interaction between nano particles and oxides supports. We examine the mean inner potential of Pd particles in Pd/TiO2 catalyst and Ag particles in Ag/TiO2 catalysts using electron holography and HRTEM. And we compare the results of the Pd/TiO2 and Ag/TiO2 systems with our previous results of the Au/TiO2 and Pt/TiO2 systems. In the case of the Pd/TiO2 catalysts, when the size of Pd particle is smaller than 5nm, the mean inner potential of Pd changes to be higher than the calculated value of the mean inner potential which is thought to be higher than the experimental values of bulk Pd by 3-5V. The mean inner potential of Pd becomes to increase gradually as the size of the Pd particle decreases. The rate of the increment in the mean inner potential of Pd is lower than that of Au/TiO2 catalysts and Pt/TiO2 catalysts. On the other hand, in the case of Ag/TiO2 catalysts, the mean inner potential of Ag does not increase though the size of the Ag particle decreases to under 2nm.
A superlattice approach to the synthesis of ferroelectric Strontium Bismuth Tantalate thin films using liquid-injection-MOCVD
Authors: Potter Richard , Awad Ahmed , Chalker Paul R. , Wang Peng , Jones Anthony C. , Noakes Timothy C.Q. , Bailey Paul 
Published: April 2011

AbstractThe synthesis of SrBi2Ta2O9 (SBT) thin films has been investigated using a superlattice approach. Thin films were deposited on silicon by independent injection of each source to produce Bi2O3/SrTa2O6 superlattices. The effects of post-deposition annealing have been investigated using high-resolution TEM and medium energy ion scattering (MEIS) to depth profile the superlattices. X-ray diffraction has also been used to characterize the conversion of the superlattices from distinct layers of Bi2O3 and SrTa2O6 into a polycrystalline layer of strontium bismuth tantalate.
Growth of Ferroelectric PbZrxTi1-xO3 (PZT) Thin Films by Liquid-Delivery Metalorganic Chemical Vapor Deposition
Authors: Matichyn Serhiy , Lisker Marco , Burte Edmund P. 
Published: April 2011

AbstractIn this study lead zirkonat titanate (PZT) thin films were deposited using direct liquid injection metal organic chemical vapor deposition (DLI-MOCVD).The chemical states and the stoichiometry of PZT-films were characterized using X-ray photoelectron spectroscopy (XPS). The crystal structure of the films was investigated by X-ray diffraction (XRD).The surface composition of the films was Pb : Zr : Ti = 1.05 : 0.52 : 0.48, which indicates that the deposited films had a stoichiometric PZT composition. 130 nm thick PZT films deposited on Ir showed <110> preferred orientation.The main role for formation of the perovsktive PZT films plays the content of the lead in the deposited films. Lead deficiency causes the formation of the pyrochlore phase with poor electrical properties. In films with a significant excess of lead a second PbO phase appeared that can be observed even with naked eyes. Negligible excess of lead can be reduced by post-deposition annealing at 500-600 °C.The Ir/PZT/Ir capacitor showed large values of the remanent polarisation of about 60μC/cm2 at an applied voltage of 3 V. So high value of the remanent polarisation can be induced by structural stress in the films. After ten switch impulses the values of the remanent polarisation have significantly decreased. This is probably due to a relaxation of crystal cells.