bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Characterization of Iron in Human Spleen
Authors: Kopani Martin , Miglierini Marcel , Lancok Adriana , Jurecka Stanislav , Dekan Julius , Melnik Milan , Sisovsky Vladimir , Mikula Milan , Manka Jan , Skratek Martin , Danihel Ludovit , Jakubovsky Jan 
Published: February 2009

ABSTRACTIron is essential element for fundamental cell functions, catalyst for chemical reaction. Iron can be found in human body mainly in the form of ferritin - 5Fe2O3.9H2O.57Fe Mössbauer spectrometry, X4ray powder diffraction, (XRD), X4ray fluorescence (XRF), scanning and transmission electron microscopy (TEM) were carried out for investigation of iron oxide particles in human spleens with diagnosis of hemosiderosis, hereditary spherocytosis, and reference sample.Room temperature Mössbauer spectra of all investigated samples exhibit doublet4like features identified as Fe(III) predominantly in ferrihydrite and haem environments within the tissue. Low temperature Mössbauer effect measurements at 77 K revealed, however, no changes in the magnetic ordering of the investigated samples. A contribution of ferromagnetically split sextets is clearly seen for all investigated samples measured at 5K. Their occurrence indicates that part of the sample is magnetically ordered, i.e. below the blocking temperature of a superparamagnetic behaviour. The ratio of relative contents of doublet to sextet components suggests differences in the size of ferritin cores in the investigated samples. The hemosiderosis sample exhibits the largest ferritin core which, in turn, stores the highest amount of Fe and thus triggers this disease.Additional structural characterization is obtained from powder XRD and XRF measurements. XRF results show presence of different chemical elements such as iron, sulphur, phosporus, chlorine, zinc, chromium, and bromine. TEM investigation reveals iron accumulation in macrophages of the human spleen. The size of the particles is around 5 μm.The amount of chemical elements and pH in surrounding environments can influence iron oxidation status and may cause transformation of biogenic to abiogenic (toxic) character of ferritin.
Detection Limits of Captured Protein on the BioCD
Authors: Barden Chad , Zhao Ming , Wang Xuefeng , Nolte David D. 
Published: February 2009

Abstract
The BioCD is a spinning biochip that uses quadrature laser interferometry to detect captured protein on the disc surface. We describe the detection limits of protein binding on this optical biosensor. The fundamental metrology limit is 1 picometer for a single 100-micron diameter spot. Under assay conditions for prostate specific antigen, we can detect 25 pg/ml at 10 assays per disc.
Effects of Device Architecture on the Performance of Organic Thin Film Transistors
Authors: Zhou Xiaojing , Mutkins Karyn E. , Elkington Daniel , Sirois Kathleen , Belcher Warwick , Dastoor Paul Christopher 
Published: February 2009

AbstractThe impact of device dimension and architecture on the device performance of an all–solution fabrication organic thin film transistor (OTFT) has been investigated. The saturation drain current is inversely proportional to the channel length, indicating that a characteristic of field–effect like transistor has been obtained. In contrast, the drain current is independent of the thickness of polyvinylphenol (PVP) dielectric layer and a large leakage current is observed at the gate electrode indicating that the device also shows electrochemical transistor characteristics. Although separate conductance measurements of a single poly(3–hexylthiophene) (P3HT) layer and a P3HT/PVP layer reveal that the conductance is proportional to the thickness of the layer, the maximum achieved drain current in the fabricated OTFT is inversely proportional to the P3HT thickness. Using this data, an interface of P3HT/PVP or a maximum P3HT thickness for a working transistor of approximately 160 ± 16 nm can be extracted. The mechanism of operation of these devices is discussed.
Resonant Fatigue Testing of Cantilever Specimens Prepared from Thin Films
Authors: Kwak Kwangsik , Otsu Masaaki , Takashima Kazuki 
Published: February 2009

AbstractFatigue properties of thin film materials are extremely important to design durable and reliable microelectromechanical systems (MEMS) devices. However, it is rather difficult to apply conventional fatigue testing method of bulk materials to thin films. Therefore, a fatigue testing method fitted to thin film materials is required. In this investigation, we have developed a fatigue testing method that uses a resonance of cantilever type specimen prepared from thin films. Cantilever beam specimens with dimensions of 1(W) × 3(L) × 0.01(t) mm3 were prepared from Ni-P amorphous alloy thin films and gold foils. In addition, cantilever beam specimens with dimension of 3(L) × 0.3(W) × 0.005(t) mm3 were also prepared from single crystalline silicon thin films. These specimens were fixed to a holder that is connected to an golddio speaker used as an actuator, and were resonated in bending mode. In order to check the validity of this testing method, Young's moduli of these specimens were measured from resonant frequencies. The average Young's modulus of Ni-P was 108 GPa and that of gold foil specimen was 63 GPa, and these values were comparable with those measured by other techniques. This indicates that the resonance occurred theoretically-predicted manner and this testing method is valid for measuring the fatigue properties of thin films. Resonant fatigue tests were carried out for these specimens by changing amplitude range of resonance, and S-N curves were successfully obtained.
Thermal Bubble Nucleation in Nanochannels: Simulations and Strategies for Nanobubble Nucleation and Sensing
Authors: Sridhar Manoj , Xu Dongyan , Hmelo Anthony B. , Li Deyu , Feldman Leonard C. 
Published: February 2009

AbstractProgress in the state of the art of nanofabrication now allows devices that may enable the experimental sensing of bubble nucleation in nanochannels, and the direct measurement of the bubble nucleation rate in nanoconfined water and other fluids. In this paper we report on two aspects in achieving this goal: 1) new molecular dynamics simulations of nanobubble formation in nanoconfined argon and water model systems and 2) an ultrasensitive nanofluidic device architecture potentially able to detect individual nanobubble nucleation events.
Functionalized Magnetic Nanoparticles for Selective Targeting of Cells
Authors: Tremel Wolfgang , Shukoor Mohammed Ibrahim , Natalio Filipe , Tahir Muhammad Nawaz , Wiens Matthias , Schladt Thomas , Barz Matthias , Theato Patrick , Schröder Heinz Christoph , Müller Werner 
Published: February 2009

ABSTRACTMnO nanoparticles were conjugated to single stranded DNA (ssDNA), Cytosin-phosphatidyl-Guanosin oligonucleotide (CpG ODN) to detect and activate Toll-like (TLR9) receptors in cells and to follow nanoparticle cellular trafficking by different means of imaging while at the same time serving as a drug carrier system. By virtue of their magnetic properties these nanoparticles may serve as vehicles for the transport of target molecules into cells, while the fluorescent target ligand allows optical detection simultaneously.x
Influence of carbon nanotube grafting on chemo-electrical properties of Conductive Polymer nanoComposites
Authors: Castro Mickaël , Lu Jianbo , Kumar Bijandra , Bruzaud Stéphane , Feller Jean-François 
Published: February 2009

ABSTRACTNew unique abilities towards solvents' vapor of electrically Conductive Polymer nanoComposites (CPCs) have made it a subject, holding the attention of research groups. The direct conversion from chemical information into an electrical signal can take advantage of existing low power microelectronics and sensing technology such as detection of toxic vapor; environmental monitoring in chemical industry and quality control in food processing, beverage and perfume industry. Conductive Polymer nanoComposite (CPC) is a heterogeneous system consisting of insulated polymer matrices and conductive nanofillers. In this paper we have investigated a new route for CNT grafting via ring opening polymerization of e-caprolactone. The influence of this treatment on chemo-electrical properties of the so-called CPC based sensor was investigated in this work.
Multifunctional Elastomer Nanocomposites based on EPDM and Carbon Nanotubes
Authors: Ciselli Paola , Lu Lan , Busfield James JC , Peijs Ton 
Published: February 2009

ABSTRACTElastomeric composites based on Ethylene-Propylene-Diene-Monomer (EPDM) filled with multi-wall carbon nanotubes (MWNTs) have been prepared, showing improved mechanical properties as compared to the pure EPDM matrix. The results have been discussed using the Guth model. The main focus of the study was on the electrical behavior of the nanocomposites, in view of possible sensor applications. A linear relation has been found between conductivity and deformations up to 10% strain, which means that such materials could be used for applications such as strain or pressure sensors. Cyclic experiments were conducted to establish whether the linear relation was reversible, which is an important requirement for sensor materials.
Direct-Write Fabrication of Polymer Nanocomposite Fibers
Authors: Berry Scott M. , Pabba Santosh , Cambron Scott D. , Cohn Robert W. , Keynton Robert S. 
Published: February 2009

ABSTRACTThe unique properties of carbon-nanotube (CNT)-doped polymers have generated several promising applications including gas sensors, high-strength/light-weight materials, and electromagnetic interference shielding. The ability to process CNT-doped materials into complex architectures may enable further advancement of these devices. We have developed a direct-write technique for processing CNT-doped poly(methyl methacrylate) (PMMA) into 3D arrays of precisely-positioned fibers with micro- and sub-microscale diameters. In this method, a programmable micromanipulator-controlled syringe was loaded with solvated CNT/PMMA and utilized to draw an array of freely-suspended solution filaments on a substrate in a “connect-the-dots” fashion. As the filaments are drawn, they are thinned by surface tension-driven necking as they dry and form solid fibers. The degree of thinning can be controlled by varying the viscosity of the solution, which acts to resist the necking while the volatile solvent evaporates and solidification occurs. Multiple fibers were drawn to investigate the effects of several factors on fiber diameter and process yield. These variables included fiber length (4, 8, and 18 mm), fiber drawing velocity (5 and 20 mm/s), polymer concentration in solution (22 and 24% by wt.), and CNT concentration in solution (0, 0.5, 1, and 1.5% by wt.), with the latter two of these variables strongly influencing solution viscosity. Measurement of the fibers via scanning electron microscopy (SEM) revealed several trends: Fiber diameter was not influenced by CNT concentration, but increased with increasing PMMA concentration (P<0.001), increasing drawing rate (P<0.01), and decreasing fiber length (P<0.001), with fiber diameter ranging from 538 nm to >100 μm. Furthermore, fiber yield exceeded 75% for all tested solutions except for the lowest viscosity CNT-doped solution (24% PMMA/0.5% CNT, η=50.1 Pa*s), which experienced capillary breakup prior to solidification. The conductivities of direct-write PMMA/CNT fibers ranged from <10-7to 0.15 S/m, with shorter fibers having higher conductivities (P<10.005). Also, fibers drawn from solutions with 1.0% CNTs had higher conductivities that those drawn from solutions with 0.5% or 1.5% CNTs (P<0.01). This nonlinear trend was further investigated by cleaving fibers in liquid nitrogen and imaging their cross-sections with an SEM. This analysis illustrated that the CNTs, which were functionalized to remain dispersed in the solvent, tended to randomly aggregate within the polymer-fiber matrix, particularly for fibers drawn from solutions containing 1.5% CNTs. In conclusion, CNT/PMMA fibers were successfully drawn with the direct-write technique and CNT doping had no significant influence on fiber diameter or yield compared with fibers drawn from PMMA homopolymer. However, the CNTs were found to strongly aggregate when drawn from solutions loaded at high concentrations (1.5%), thereby hindering electrical transport.
Matrix Formation Leading to Catalyst Free Growth of GaN Nanowires
Authors: Halpern Joshua B. , Harris Gary L. , He Maoqi , Zhou Piezhen , Cheek Christina E. 
Published: February 2009

ABSTRACTCatalyst-free vapor-solid GaN nanowire growth occurs when ammonia flows over Ga first forming a GaN matrix, the top layer of which is composed of hexagonal platelets. Multiphase nanowire growth occurs at nanoscale nucleation sites on the GaN platelets. Lower layers of the matrix are Ga rich, upper ones are stoichiometrically GaN. Gallium for later stages of growth is sourced from the decomposition of GaN particles and Ga rich GaN. Growth temperature exerts a strong influence on nucleation site formation. Scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) was used to characterize the matrix.
Effect of Metal - Silicon Nanowire Contacts on the Performance of Accumulation Metal Oxide Semiconductor Field Effect Transistor
Authors: Garg Pranav , Hong Yi , Iqbal Md. Mash-Hud , Fonash Stephen J. 
Published: February 2009

ABSTRACTRecently, we have experimentally demonstrated a very simply structured unipolar accumulation-type metal oxide semiconductor field effect transistor (AMOSFET) using grow-in-place silicon nanowires. The AMOSFET consists of a single doping type nanowire, metal source and drain contacts which are separated by a partially gated region. Despite its simple configuration, it is capable of high performance thereby offering the potential of a low manufacturing-cost transistor. Since the quality of the metal/semiconductor ohmic source and drain contacts impacts AMOSFET performance, we repot here on initial exploration of contact variations and of the impact of thermal process history. With process optimization, current on/off ratios of 106 and subthreshold swings of 70 mV/dec have been achieved with these simple devices
Growth and Characterization of p-n Junction Core-Shell GaAs Nanowires on Carbon Nanotube Composite Films
Authors: Mohseni Parsian , Lawson Gregor , Adronov Alex , LaPierre Ray 
Published: February 2009

ABSTRACTThin films composed of poly(ethylene imine)-functionalized single-walled carbon nanotubes (CNTs) were formed through a vacuum filtration process and decorated with Au nanoparticles, roughly 40 nm in diameter. The Au nanoparticles, on the surface of the CNT fabric, accommodated the growth of GaAs nanowires (NWs), according to the vapour-liquid-solid (VLS) mechanism, in a gas-source molecular beam epitaxy (GS-MBE) system. Structural analysis indicated that the nanowires, up to 2.5 μm in length, were not preferentially oriented at specific angles with respect to the substrate surface. The NWs grew in the energetically favored [0001] direction of the wurtzite lattice while stacking faults, characterized as zincblende insertions, were observed along their lengths. Micro-photoluminescence spectroscopy demonstrated bulk-type optical behaviour. Current-voltage behaviour of the core-shell pn-junction heterostructured NWs exhibited asymmetric rectification. Thus, the potential for the incorporation of such hybrid NW/CNT architectures into an emerging class of flexible opto-electronic devices is demonstrated.
Silver nanowires: synthesis, characterization and optical properties
Authors: Barnakov Yuri A. , Li Heng , Zhu Guohua , Mayy Mohammed , Robinson Erik J. , Bonner Carl , Noginov Mikhail A. 
Published: February 2009

ABSTRACTWe describe electrochemical synthesis of a bulk metamaterial, consisting of silver nanowires in Porous Anodic Alumina membrane and its characterization. We have found that the quality of the synthesized metamaterial depends on the metal used as a working electrode at the optimal conditions of the electroplating process. The dissolution of the thin layer of working electrode is occurred during the electrochemical reaction. It suggests an important role of interfacial phenomena taking place between the working electrode and the sample holder.
The Strength of Gold Nanowires and Nanoporous Gold
Authors: Dou Rui , Derby Brian 
Published: February 2009

ABSTRACTWe have measured the yield strength of gold nanowires with diameters in the range from 30 to 70 nm fabricated by electro-deposition into porous alumina templates. All nanowire sizes showed yield strengths much greater than polycrystalline gold with the 30 nm specimens having a yield strength of 1.4 GPa. We found no significant work hardening at plastic strains up to 30%. The strength of the nanowires as a function of wire diameter follows the same trend as has been found for the compression strength of larger gold pillars reported in the literature. TEM observations of deformed wires are consistent with mechanisms of dislocation induced deformation. The strength of nanoporous gold nanowires measured by uniaxial compression test is also reported here. Although two different mechanisms are thought to operate in gold nanowires and nanoporous gold respectively, their strengths show very similar dependence on wire or ligament diameter. However the nanoporous material shows significant strain hardening.
Modifying the Pore Size of Resorcinol Formaldehyde Aerogels for Fabrication of Hollow Spheres for Direct Drive ICF Experiments
Authors: Paguio Reny , Federick Chris A. , Ilavsky Jan , Hund Jared F. , Nikroo Abbas , Thi Mary A. 
Published: February 2009

AbstractThis work investigates an alternative way to modify the pore size of a 100 mg/cc resorcinol formaldehyde (R/F) aerogel without any significant change to the aerogel target density. This was successfully accomplished by an addition of hydrophilic polymer additive [Poly Vinyl Alcohol (PVA) or Poly Acrylic Acid (PAA)] to the R/F precursor solution which acts as an impurity in the reaction. The polymer can modify the cross linking or aggregation of the primary particles which can change the structure formation of the aerogel, thus changing the pore size. This paper will discuss this process modification and the fabrication of hollow, large pore R/F aerogel spheres that are used for direct drive inertial confinement fusion (ICF) cryogenic ice layering experiments at the University of Rochester Laboratory for Laser Energetics (LLE). The aerogels were characterized using scanning electron microscopy (SEM), nitrogen gas adsorption, and ultra small angle x-ray scattering (USAXS).
Neutron Studies of the Iron-based Family of High Tc Magnetic Superconductors
Authors: Lynn Jeffrey W. 
Published: February 2009

AbstractWe briefly review recent neutron scattering investigations carried out at the NIST Center for Neutron Research on the crystal structures, magnetic structures, and spin dynamics of the iron-based ROFe(As,P) (R=La, Ce, Pr, Nd), and (Ba,Sr,Ca)Fe2As2 systems. All the undoped materials exhibit universal behavior, where a tetragonal-to-orthorhombic structural transition occurs between ˜100−220 K, below which the systems become antiferromagnets. The magnetic structure within the a-b plane consists of chains of parallel Fe spins that are coupled antiferromagnetically in the orthogonal direction, with an ordered moment typically less than one Bohr magneton. Hence these are itinerant electron magnets, with a spin structure that is consistent with Fermi-surface nesting and a spin wave bandwidth ˜200 meV. The rare-earth moments order antiferromagnetically at low T like ‘conventional’ magnetic-superconductors. With doping, the structural and magnetic transitions are suppressed in favor of superconductivity, with superconducting transition temperatures up to 56 K, while the Ce crystal field linewidths are affected when superconductivity sets in. The application of pressure in CaFe2As2 transforms the system from a magnetically ordered orthorhombic material to a ‘collapsed’ non-magnetic tetragonal system which is superconducting at lower T when anisotropic pressure is applied. Fe1+xTe shows a transition from a monoclinic to orthorhombic low T structure with increasing x, and a crossover from commensurate to incommensurate magnetic order. Se doping suppresses the magnetic order, while incommensurate magnetic scattering is observed in the superconducting regime.
Synthesis of layered double hydroxides in W/O micro-emulsion: Influence of method of preparation on the physico-chemical and adsorption characteristics
Authors: Mandal Sujata , Deshpande Aniruddha S. , Harle Arti S. , Mayadevi S. 
Published: February 2009

ABSTRACTZn/Al layered double hydroxide was synthesized in micro-emulsion system with the oil phase comprising of cyclohexane + TX100 (surfactant) + n-hexanol (co-surfactant). Aqueous NaOH solution was used as the precipitating agent. The XRD pattern showed Zincite as the primary and hydrotalcite as the secondary phase. The d003 diffraction peak corresponded to interlayer hydroxide ion. There was no interlayer NO3- ion. The synthesized LDH showed much higher BET surface area (116.3 m2/g) than similar LDH synthesized by conventional co-precipitation technique (4.2 m2/g). Well defined flaky nano-crystals having an average dimension of 5-20 nm were observed by HRTEM.
Structural Transformation and Mechanical Properties of Cold Sprayed Nickel Coatings after Annealing
Authors: Zou Yu , Rezaeian Ahmad , Szpunar Jerzy , Irissou Eric , Yue Stephen 
Published: February 2009

ABSTRACTCold spray is a relatively new coating technology in which coatings can be produced by powdered particles under large plastic deformation without significant heating. In this paper, nickel coatings were fabricated by cold spray process followed by heat treatment in inert gas. Structural transformation of both as-sprayed and annealed coatings was investigated by Electron Backscattering Diffraction (EBSD) in a FEG-SEM. The results show that after cold spraying sub-micron grains and subgrains with high crystal strain appear in the particle bond interface, but not shown in the center of particles. Microstructure was transformed to be uniform and stresses were released after annealing in 400°C for one hour. And ductility and formability were significantly improved due to recovery and recrystallization. Continuous recrystallization after large strain deformation could occur after cold spraying followed by annealing.
Mercury concentrations in Southern Beaufort Sea polar bears: Variation based on stable isotopes of carbon and nitrogen
Authors: Cardona-Marek Tamara , Knott Katrina K. , Meyer Benjamin E. , O'Hara Todd M. 
Published: February 2009

Abstract
Total Hg concentration was measured in hair and whole blood of 52 adult Southern Beaufort Sea polar bears (Ursus maritimus) captured in the spring of 2005. Stable isotopic signatures (i.e., 13C/12C, δ13C; 15N/14N, δ15N) in hair and two blood compartments (packed blood cells/clot and serum) were determined to assess the variation of Hg concentrations among polar bears in relation to their feeding ecology and other biological factors. Concentrations of Hg in hair and blood (2.2–23.9 μg/g dry wt and 0.007–0.213 μg/g wet wt, respectively) were within the range of values previously reported for polar bears in Canada and East Greenland. Mercury concentration in hair from females was higher than that in hair from males, and concentration was related to interactions between δ13C, δ15N, and longitude of capture location. Mercury concentrations in hair were inversely correlated to δ13C in hair and blood, suggesting that polar bears with greater total Hg concentrations fed more on pelagic prey, such as ringed seals or beluga whale, than on benthic prey. Variability in Hg concentrations in polar bear hair and blood may be the result of intraspecific or regional variation in prey selection rather than strictly trophic level interactions.