bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetite-PLGA Microparticles for Oral Delivery of Insulin
Authors: Cheng Jianjun , H. Yim Christopher , Teply Benjamin A. , Ho Dennis , Farokhzad Omid C. , Langer Robert S. 
Published: June 2019

AbstractMagnetic responsive particles were designed for use in oral delivery of insulin. Magnetite nanoparticles (12 nm average size) were synthesized and co-encapsulated with insulin into poly(lactide-co-glycolide) (PLGA) microparticles (4.6 ± 2.2 μm average particle size) through the double-emulsion method. The spherical structures of resulting microparticles were well maintained at magnetite content 5 wt % or less. Mice were gavaged with 125I-insulin-magnetitePLGA microparticles and a circumferential trans-abdominal magnetic field was applied forty minutes after administration to retard the transit of the microparticles in the intestinal tract. As control, mice were similarly dosed without the subsequent trans-abdominal magnetic field. Mice were sacrificed, and the intestinal radioactivity was 101% and 145% higher in treated mice versus the control at 6 h and 12 h, respectively. A single administration of 50 unit/kg Humulin Rmagnetite-PLGA microparticles to the fasted mice resulted in 66% reduction of blood glucose level in the presence of external magnetic field at 12 h, compared to 27% reduction in the absence of magnetic field.
Ferromagnetic Mn-Doped GaN Nanowires for Nanospintronics
Authors: Han Doo Suk , Na Chan Woong , Jang Woo Sung , Bae Seung Yong , Park Jeunghee 
Published: June 2019

AbstractWe report Mn-doped GaN nanowires exhibiting ferromagnetism even at room temperature. The growth of single-crystalline wurtzite structured GaN nanowires doped homogeneously with about 5 atomic % Mn was achieved by chemical vapor deposition using the reaction of Ga/GaN/MnCl2 with NH3. The ferromagnetic hysteresis at 5 and 300 K and the temperature-dependent magnetization curves suggest the Curie temperature around 300 K. Negative magnetoresistance of individual nanowires was observed at the temperatures below 100 K.
Formation of 2-D and 3-D Arrays of Colloidal Co Magnetic Nanoparticles
Authors: Chushkin Y. , Chitu L. , Luby S. , Majkova E. , Satka A. , Holy V. , Ivan J. , Giersig M. , Hilgendorff M. , Metzger T. H. , Konovalov O. 
Published: June 2019

AbstractOrdering of Co nanoparticles (∼11 nm in diameter) into 2-D and 3-D arrays on Si/Si3N4 substrates in external magnetic field and without field is reported. Arrays of particles were studied by TEM, SEM and GISAXS. The GISAXS measurements were performed at the wavelengths 0.155 nm and 0.336 nm and the spectra were simulated using distorted wave Born approximation approach. From results it follows that 2-D ordered monolayers of particles are composed of hexagonal close-packed mosaic blocks. 3-D arrays – rods are formed along magnetic field direction, being parallel or perpendicular to the substrate surface, when the colloid was more concentrated. Distribution of particles in rods was analyzed only by GISAXS and it was described by close packing of hard spheres. Their effective diameter was 14.7 nm.
Self Assembled Iron Nanowires: Morphology, Electrical and Magnetic Properties
Authors: Huelser T.P. , Wiggers H. , Knipping J. , Roth P. , Lorke A. 
Published: June 2019

AbstractWe report on the self-assembled formation of iron nanowires from iron nanoparticles. Nanosized iron particles with a diameter of about 35 nm are synthesized by thermal decomposition of iron pentacarbonyl Fe(CO)5 in a hot wall reactor. This particle size is chosen to produce single domain ferromagnetic particles. As a result, the particles are attracted by magnetic forces, leading to iron nanowires of up to 300 μm in length. HRTEM and EELS investigations give detailed morphological, structural and chemical information. They reveal a big metallic iron core surrounded by an iron oxide shell with a thickness of 3-4 nm, originating from self limiting surface oxidation under ambient conditions. For electrical characterization, single iron wires are thermophoretically sampled on interdigital contacts. Impedance spectroscopy on single nanowires indicates both, capacitive and ohmic contributions to the overall conductivity. Magnetic properties are investigated with SQUID magnetometry. Magnetization measurements reveal a saturation magnetization of 160 emu/g at 5 K, which is more than 70% of the iron bulk value.
Formation and Characterization of Magnetic Multilayer Ni/Cu Nanowires
Authors: Liu R. S. , Chang S. C. , Hu S. F. , Huang C. Y. 
Published: June 2019

AbstractHighly ordered composite nanowires with multilayer of Ni/Cu, have been fabricated by pulsed electrodeposition into nanoporous alumina membrane. The diameter of wires can be easily controlled by pore size of alumina, ranging from 30 to 100 nm. The applied potential and the duration of each potential square pulse determine the thickness of the metal layers. The nanowires have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer (VSM) measurements. From the result of MFM analysis, the magnetic multilayer nanowires indicate unique magnetic property. The MFM images indicate that every ferromagnetic layer separated by Cu layer was present as single isolated domain like magnet. This technique has potential for use in the measurement and application of magnetic nanodevices.
Self Seeded ZnO Nanowire Growth by Ultrasonic Spray Assisted Chemical Vapour Deposition
Authors: Wei M. , Zhi D. , MacManus-Driscoll J. L. 
Published: June 2019

AbstractZnO, which exhibits a direct bandgap of 3.37 eV at room temperature with a large exciton binding energy of 60 meV,is of considerable technological importance because of its potential use in short-wavelength devices, such as ultraviolet (UV) light-emitting diodes and laser diodes. The fabrication and application of 1-D ZnO nanostructures has attracted considerable interest in recent years. In this work, we produced single crystal nanowires of zinc oxide using a novel self-seeded growth using ultrasonic spray assisted chemical vapour deposition, in which a nanocrystalline seed layer was first deposited onto a glass substrate and the nanowires subsequently grown using a different precursor concentration and substrate temperature. The diameter of the nanowires is in the range of 20-80 nm and the length of the wires is as long as 10 μm. The single crystal nature of the nanowires was revealed by high resolution transmission electron microscopy. The formation of liquid droplets due to the reducing atmosphere and the higher temperature during the nanowire growth was found to be the key step of the ZnO nanowire formation.
Synthesis of Metal Carbides Using Biological Templates
Authors: Shin Yongsoon , Li Xiaohong S. , Samuels William D. , Wang Yong , Pederson Larry R. , Exarhos Greg J. 
Published: June 2019

AbstractNanocrystalline metal carbides (MC: M=Si, Ti) have been prepared using cellulose network mineralized with silica and titania by carbothermal reduction at high temperature in Ar. Hierarchical biological structures indigenous to the cellulose precursor were completely replicated after the reaction. Cubic phase MC composites show relative low oxygen content 0.24 wt% and a high lattice parameter of 4.327Å in TiC. The particle sizes of the MC composites are 200-700nm for SiC and 10-50nm for TiC, and high BET surface area, up to 150m2/g.
Combined UHV and Liquid Phase (CULP) Processing of Self-assembled Nanostructures
Authors: Ogun Samil E. , Tung Raymond T. 
Published: June 2019

AbstractThe fabrication and structures of nanometer sized metal and semiconductor dots by a new “combined UHV and liquid-phase processing” (CULP) method are investigated. Ultrahigh vacuum deposition of monolayers of material, buffered and co-adsorbed along with chemically-inert working gas molecules, and subsequent pressurization in situ with high purity helium, led to self-assembly of metal and semiconductor nanoparticles in the liquid phase. The density and size distribution of nanoparticles were found to depend on processing parameters including the substrate surface condition and the dilution of the co-adsorbed film. These results are discussed in terms of surface and interface energies and kinetics.
Improved Crystallinity of Zinc Sulfide Nanoparticles in Aqueous Environment
Authors: Goswami Navendu , Sen P. 
Published: June 2019

AbstractZinc sulfide nanoparticles, prepared employing a non-equilibrium route, are investigated for surface related effects. Water has been shown to induce a structural transformation in nanoparticles prepared this way, which is not related to their particle size. Employing Fourier transform infrared spectroscopy and x-ray powder diffraction, we show here the importance of S-H interaction in the buildup to the final ZnS structure of these nanoparticles. These particles hold promise as water sensors.
AFM Analysis Of Nano-Copper Surface Morphology
Authors: Lohmus Rynno , Hussainova Irina , Kommel Lembit , Siimon Hele 
Published: June 2019

AbstractSurface morphology and features of pure copper heavily deformed by equal channel angular pressing were studied by means of an atomic force microscope (AFM) and scanning electron microscope (SEM) techniques. Surface characterization helps to develop a better understanding of microstructure evolution of materials subjected to any kind of mechanical loading and thermal treatment. The main objectives of this study are to exploit the capabilities of AFM to accurately perform an analysis of the surface features of nano-structured copper subjected to plastic deformation and heat treatment; and examination of the mechanical characteristics influenced by material's microstructure. It is shown that the AFM technique can be extremely useful for the investigations of a surface topography of materials.
Unusual fracture behavior of nanoporous polymeric thin-films
Authors: Kearney Andrew V. , Dauskardt Reinhold H. , Mohler Carol E. , Mills Michael E. 
Published: June 2019

AbstractWe present surprising evidence that the fracture resistance of porous forms of poly(arylene) ether (PAE) films exhibit increasing fracture resistance with increasing porosity. Such behavior is in stark contrast to the fracture toughness of porous solids, which typically decrease markedly with increasing porosity. A fracture mechanics based model is presented to rationalize the increase in fracture toughness of the voided polymer film and explain the behavior in terms of the pore size and volume fraction. It is shown that a certain dependence of pore size and volume fraction is required to increase rather than decrease the fracture resistance. The research has implications for the optimum void size and volume fraction needed to enhance the fracture resistance of porous ductile polymer films.
Development of Evaluation Method for Delamination Strength Between Micro-Sized Materials in MEMS Devices
Authors: Ishiyama Chiemi , Hata Junichi , Koyama Satoru , Sone Masato , Higo Yakichi 
Published: June 2019

AbstractEvaluation method for delamination strength of micro-sized materials has been developed using by FEM and measurement of load-displacement curve of micro-sized specimen. This evaluation method is applied to micro-sized cylindrical SU-8 specimens on Si substrate. The maximum shear stress between SU-8 and Si was analyzed with FEM. Fracture load required to delaminate the two materials was examined using a mechanical testing machine for micro-sized materials, which have been developed in our group. The delamination strength was determined from the maximum shear stress and the fracture load.
Size Effect in the Plasticity of Multiscale Nanofilamentary Cu/Nb Composite Wires During in-situ Tensile Tests Under Neutron Beam
Authors: Vidal Vanessa , Thilly Ludovic , Van Petegem Steven , Stuhr Uwe , Lecouturier Florence , Renault Pierre-Olivier , Van Swygenhoven Helena 
Published: June 2019

AbstractCopper-based high strength nanofilamentary wires reinforced by bcc nanofilaments (Nb or Ta) are prepared by severe plastic deformation for the winding of high pulsed magnets. In-situ tensile tests under neutron beam were performed on a Cu/Nb nanocomposite composed of a multiscale Cu matrix embedding 554 Nb filaments with a diameter of 267 nm and spacing of 45 nm. The evolution of elastic strains for individual lattice plane in each phase and peak profiles in the copper matrix versus applied stress evidenced the co-deformation behavior with different elastic-plastic regimes and load sharing: the Cu matrix exhibits size effect in the finest channels while the Nb nanowhiskers remain elastic up to the macroscopic failure, with a strong load transfer from the copper matrix onto zones that are still in the elastic regime. Taking into account results from residual lattice strains also determined by neutron diffraction, the yield stress in the finest Cu channels is in agreement with calculations based on a single dislocation regime.
Modeling Ductile/Brittle Behavior in Polymeric Microlaminates: Effect of Volume Fraction
Authors: Sharma Rajdeep , Boyce Mary C. , Socrate Simona 
Published: June 2019

AbstractIn this work we present a micromechanical model for two-phase ductile/brittle laminates that captures the macroscopic behavior, as well as the underlying micro-mechanisms of deformation and failure, in particular the synergy between the inelastic deformation mechanisms of crazing and shear yielding. The finite element implementation of our model considers a three-dimensional representative volume element (RVE), and incorporates continuum-based physics-inspired descriptions of shear yielding and crazing, along with failure criteria for the ductile and brittle layers. The interface between the ductile and brittle layers is assumed to be perfectly bonded. The model successfully explains the volume fraction effect on the micro and macromechanics of ductile/brittle microlaminates subjected to uniaxial tension.
An Investigation of the Influence of Interface Chemical Structure on Fiber/Matrix Adhesion
Authors: Raghavan Dharmaraj 
Published: June 2019

AbstractThe primary objective of the study is to investigate the impact of chemical structure at the interface on the interface strength of fiber/matrix composite. A solvent based method was used to deposit trichlorosilane on E-glass fiber surfaces followed by in situ modification of the deposited layer to prepare pure and mixed amine undecyl self assembled monolayer (SAM). The extent of fiber/matrix adhesion was determined by performing single fiber fragmentation test (SFFT). The SFFT data indicate that ≈ 85 % of fiber breaks obtained for epoxy composite occurs at a much lower mass fraction of amine coverage for SAM while a similar number of fiber breaks occur at a much higher mass fraction of amine coverage for aqueous solution deposited coupling agent system.
Flexural Stiffness Domains for Bi-material Multilayered Systems [Abstract + Supplemental Data]
Authors: Pasini Damiano 
Published: June 2019

AbstractThe development of different concepts for a two-materials system consisting of symmetric and asymmetric layers has been demonstrated. Flexural stiffness domains governed by flexural modulus, density, and layer geometry have been visualized on efficiency maps. It is demonstrated that although a bi-material system can evolve in several symmetric and asymmetric multilayers, the flexural properties of all the possible configurations fall into a region. This is bounded by two curves describing three symmetric layers sandwiches.The characterization of the flexural properties is based on a method recently introduced to model the mass-efficiency of monolithic structures [1]. The scheme is based on shape parameters, called Shape Transformers, which govern the geometric properties of the planar shape of a cross-section. These factors can classify shapes into families and classes with respect to the cross-section figure, and regardless size. Such a model is applied here to a bi-material laminate composite to take into account position and arrangement of layers. It can be used at the meso- as well as micro scale to predict the flexural stiffness of design alternatives for a multilayers bi-material.The rationale of the method hinges on the decoupling of material, shape and size, such that the design variables can be optimized separately. This feature is exploited to develop properties charts. When families and classes of shapes are visualised, domains of properties emerge with respect to the Shape classification. The domains are bounded by optimization paths, which identify the rules of mixture of a shape concept.In a case study, the efficiency of monolithic shaped beams is compared to that of bi-material multilayers composites for different constraints applied to the cross-section size. The maps offer ways to exploit the potential of both material and cross-section geometry, especially for concept design. The maps ease the visual ranking, widen the spectrum of choices, and enable the contrast of design alternatives, in a glance.
Polymer Assessment for Magnetic Shape Memory Alloy Composites
Authors: Underhill Royale S , Keddy Gregory A , Farrell Shannon P 
Published: June 2019

AbstractOur surrounding environment is teeming with useful energy, waiting to be harnessed (i.e., solar, wind, tidal, etc.). If this energy can be exploited at the point where it is required, then the need to carry additional power sources can be reduced. In recent years, magnetic shape memory alloys (MSMA) have demonstrated an ability to convert mechanical energy to magnetic energy. Such conversions have lead to the investigation of these alloys for energy harvesting applications.There are a number of issues to address when forming a MSMA/polymer composite. The polymer must be stiff enough to transmit the induced strain through the entire matrix, yet soft enough not to exceed the MSMA blocking stress. Also, the polymer must not dampen any force applied before it can be transmitted to the MSMA particles.Ten polymers have been investigated for MSMA/polymer composites. The work presented here will describe progress in nickel-manganese-gallium (Ni-Mn-Ga)/polymer composite fabrication and characterization. Special attention will be given to polymer selection, optimizing particle dispersion and MSMA/polymer interfacial interactions.
Exploring simulation methods for self-healing oxide films
Authors: Lazic Ivan , Thijsse Barend 
Published: June 2019

AbstractNew methods for modeling oxide film growth using MD (molecular dynamics) simulations are explored in order to study the atomic mechanism of the self-healing oxidation phenomenon in metal/oxide systems. A modified MEAM (modified embedded atom method) potential is proposed and extended by a variable charge ionic potential model from the literature, for which the PPPM (particle-particle-particle-mesh) was used as Coulomb solver. In this work the first results are reported. The ionic potential model is tested in combination with the PPPM solver. The results are excellent.
Brittle-Ductile Transition in Heterogeneous Metallic Materials [PowerPoint Submission]
Authors: Noronha Silvester John , Ghoniem Nasr M 
Published: June 2019

AbstractWe present a model for the brittle - ductile transition in heterogenous metallic materials based on two dimensional discrete dislocation simulations of crack-tip plasticity. The sum of elastic fields of the crack and the emitted dislocations defines an elasto-plastic crack field. Effects of crack-tip blunting of the macrocrack are included in the simulations. The plastic zone characteristics are found to be in agreement with continuum models, with the added advantage that the hardening behavior comes out naturally in our model. The present model is composed of a macrocrack with microcracks ahead of its tip. These microcracks represent potential fracture sites at internal inhomogenities, such as brittle precipitates. Dislocations that are emitted from the crack-tip account for plasticity. When the tensile stress at the microcrack situated along the crack plane attains a critical value over a distance fracture is assumed to take place. The brittle-ductile transition curve is obtained by determining the fracture toughness at various temperatures. Factors that contribute to the sharp upturn in fracture toughness with temperature are found to be: the decrease in tensile stress ahead of the crack tip due to increase in blunting, and the increase in dislocation mobility. The inherent scatter in fracture toughness measurements are studied by using a size distribution for microcracks, distributed on the crack plane of the macrocrack. The scatter in fracture toughness measurements is found to be an effect of the size distribution of microcracks rather than their spatial distribution on the matrix ahead of the crack plane. When compared, the obtained results are in agreement with the existing experimental data.
Single-Crystals of a New Carbon Nitride Phase with all-sp3 Carbon
Authors: Kroll Peter , Horvath-Bordon Elizabetha , Riedel Ralf , McMillan Paul F , Aken Peter van , Miehe Gerhard , Hoppe Peter , Boehler Reinhard 
Published: June 2019

AbstractWe prepared a carbon nitride compound by treating the molecular precursor C2N4H4 in a laser-heated diamond-anvil-cell (LH-DAC) at pressures exceeding 27 GPa and temperatures above 1700°C. After quenching we recovered single crystals of the new material with diameters of about 1 μm. Using several experimental characterization techniques in conjunction with computational methods we determined composition, hybridization of constituting atoms, and the crystal structure. The new carbon nitride imide, C2N2(NH), adopts a defect-wurtzite structure and is isotypic to Si2N2(NH).
Probing of Structure Factor of Water to 57 GPa and 1500 K
Authors: Goncharov Alexander F. , Sanloup Chrystele , Goldman Nir , Crowhurst Jonathan C. , Fried Lawrence E. , Guignot Nicola , Mezouar Mohamed , Meng Yue 
Published: June 2019

AbstractThe x-ray structure factor of water has been measured along the melting line to 57 GPa and 1500 K using focused monochromatic synchrotron radiation and laser heated diamond anvil cell. The oxygen radial distribution function, g(r) is determined from these data. We have also calculated g(r) using ab initio methods and find a good agreement with the experiment. Based of the similarity of the measured and calculated structure factors determined density of water under extreme conditions unattainable previously.
Pressure-Induced Distortive Phase Transition in Chromite-Spinel at 29 GPa
Authors: Shu Jinfu , Mao Wendy L. , Hemley Russell J , Mao Hokwang 
Published: June 2019

AbstractA natural chromite single crystal was compressed in a helium pressure medium to just above 35 GPa at ambient temperature and studied with energy-dispersive x-ray diffraction. The volume compression of the cubic, spinel-type structure was fit to a third-order Birch-Murnaghan equation of state with parameters a0= 8.338(4) Å, V0 = 579.6(9) Å3, K0 =179(10) GPa, and K' = 3.9(9) up to 29 GPa. A distortive phase transition was discovered at higher pressures to a CaAl2O4-type orthorhombic structure, with two cubic unit-cell axes increasing and the third decreasing with increasing pressure. The transition can be fit to a Landau-type strain-order formulism with approximately 5% volume decrease from the cubic phase at 35 GPa. The transition may be triggered by electronic or magnetic transitions in the 3d elements Fe and Cr cations.