bluuebunny/crossref_metadata_2025 huggingface dataset:
SUPERCONDUCTIVITY ENHANCEMENTS IN SMALL METALLIC GRAINS
Authors: ZHENG RENRONG , CHEN ZHI QIAN , ZHU SHUN QUAN
Published: August 2005

The reasons for superconductivity enhancement in small metallic grains including hundreds of thousand electrons are investigated by solving the generalized gap equation based on BCS mean field theory. The analysis suggests that the superconductivity enhancement in small metallic grains are the results caused by the pairing correlation and the level statistics in the Gaussian orthogonal ensemble (GOE) and the Gaussian unitary ensemble (GUE).
ANALYSIS OF GaAs/AlAs SUPERLATTICE STRUCTURE BY X-RAY DOUBLE-CRYSTAL DIFFRACTION
Authors: LI L. , ZHONG J. C. , LI M. , WANG X. H. , LIU G. J.
Published: August 2005

The high quality GaAs/AlAs superlattice structures are characterized by X-ray double-crystal diffraction. The structure parameters of the superlattice are obtained from the rocking curve. The first and second satellite peaks appear around the main 0th-order peak. The FWHMs of 0th-order peak and GaAs substrate are quite close, showing much higher integrity of the crystal lattice. The superlattice structure period D, GaAs thick-ness LB and AlAs thickness LZ can be calculated according to the measured angular distance between the diffraction peaks. The experimental results show that the measured values are the same as the designed results. They are useful for improving the quality of superlattice.
THICKNESS DEPENDENCE OF MORPHOLOGY IN La2/3Ca1/3MnO3 THIN FILMS
Authors: ZHANG Y. M. , WU X. S. , JIANG S. S. , TAN W. S. , GAO J.
Published: August 2005

La2/3Ca1/3MnO3 (LCMO) thin films with the thickness from 4 nm to 50 nm were fabricated by the off-axis magnetron sputtering technique. Single crystal (001) SrTiO3 (STO), (0001) sapphire (ALO), and (001) yttrium-stabilized ZrO2 (YSZ) were used as substrates. The surface morphology of thin films was characterized by atomic force microscope (AFM). The surface morphology of the thin films depends on the thickness. Thin films on STO substrates with the thickness less than 20 nm show a wave-like morphology, which indicates a two-dimension growth mode. With the thickness increases, some cracks and grains appear on the surface, which indicates the release of the lattice strain due to the lattice mismatch between the substrate and the films. The morphology became smoother with the thickness more than 30 nm, which indicates the full relaxation in strain for the film. The surface roughness and the average grain size increase with the thickness. The morphology for LCMO grows on ALO and YSZ show a rougher surface than that on STO. The rough surface morphology may indicate the wide metallic-to-insulating transition in transport properties.
CLUSTERING PHENOMENON BY RANDOM TWO-BODY INTERACTIONS AND THE Jmax PAIRING INTERACTION
Authors: ZHAO YU-MIN , ARIMA AKITO
Published: August 2005

In this talk we first explain the context of a topic called "regularities for many-body systems in the presence of random two-body interactions". Then we discuss the robustness of the α clustering phenomenon in the presence of random two-body interactions. Last, we discuss a clustering picture of fermions in a single-j shell with the J max pairing interaction.
MANY-BODY INTERACTIONS AMONG HELIUM ATOMS AND EQUATION OF STATE OF DENSE HELIUM AT HIGH DENSITIES AND TEMPERATURES
Authors: LIU FUSHENG , TIAN CHUNLING , CAI LINGCANG , JING FUQIAN
Published: August 2005

Based on ab initio self-consistent-field technique and atomic cluster method, the various many-body interactions among atoms in dense helium have been computed. By this way, the static high pressure measurements are perfectly explained. A new simple formula for calculation the total energy is proposed by directly combining the two-body potential with the atomic potential. Over a large volume and temperature range of 7.5~1.74 cm3/mol and 2000~21000K, the equation of state (EOS) of helium is given.
SPIN CLUSTER AS A QUBIT: ROBUST AGAINST DISSIPATION OF THERMAL RADIATION FIELDS
Authors: SU XIAO-FEI , WANG SHUN-JIN
Published: August 2005

A spin cluster of 3 spin 1/2 particles has been studied as a qubit system. A time dependent magnetic field is applied to control the time evolution of the cluster. The lowest energy level of the cluster has the total spin 1/2 separated far away from the excited states and can be used as a qubit register. The universal 1-qubit logic gate can be constructed from the time evolution operator of the non-autonomous many-body system, and the 6 basic 1-qubit gates can be realized by adjusting the applied time dependent magnetic field. As a many-body system, this qubit system is expected to be robust against the dissipation effect of the thermal radiation fields from the environment.
THRESHOLD KINETIC ENERGY FOR GOLD X-RAY EMISSION INDUCED BY HIGHLY CHARGED IONS
Authors: ZHAO Y. T. , XIAO G. Q. , ZHANG X. A. , YANG Z. H. , ZHANG Y. P. , CHEN X. M. , ZHANG H. Q. , CUI Y. , SHAO J. X. , XU X. , LI F. L.
Published: August 2005

The X-rays induced in the interaction of highly charged Argon ions with gold surface were investigated. We had altered the projectile kinetic energy from 150keV to about 400keV. The results show that, there is a threshold projectile kinetic energy for this excitation. Combining the colliding theory of classic electrodynamics with the concept of quantized orbits, we crudely give this threshold kinetic energy.
SONOCHEMICAL SYNTHESIS AND MICROSTRUCTURE CHARACTERIZATION OF Fe3O4 AND ZnFe2O4 NANOCRYSTALLINES
Authors: ZHU JIANMIN , HUANG SHISONG , MA GUOBIN , MING NAIBEN
Published: August 2005

By means of sonochemical method, Fe 3 O 4 and ZnFe 2 O 4 nanocrystallines can be synthesized from FeCl 2/ urea and ZnCl 2/ FeCl 2/ urea in water. The products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) as well as selected area electron diffraction (SAED). Special attention was paid to the microstructure of the nanocrystallines using high-resolution transmission electron microscopy (HREM). Probable mechanisms for the sonochemical formation of Fe 3 O 4 and ZnFe 2 O 4 nanocrystallines are discussed.
SYNTHESIS AND CHARACTERIZATION OF FERROELECTRIC NANOCRYSTAL POWDERS OF SrBi2Ta2O9 BY A POLYMERIZABLE COMPLEX METHOD
Authors: CHENG JIN-BO , LI AI-DONG , SHAO QI-YUE , TANG YUE-FENG , WU DI
Published: August 2005

Ferroelectric nanocrystal powders of SrBi2Ta2O9 (SBT) have been first prepared by a polymerizable complex (PC) route. The bismuth powder, strontium carbonate, and water-soluble tantalum oxalate solution were used as starting materials. Thermal analyses (TGA and DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and conventional BET method were explored to characterize the structure, morphology, and specific surface area of PC-derived SBT powders calcined at 500-850 °C. As control samples, SBT powders were also fabricated by metalorganic decomposition (MOD) method. The XRD and TEM results indicate that high pure and well crystalline powders can be obtained at 650 °C with a average size of 50 nm. The PC-derived powder has much larger surface area than MOD-derived powder. The BET value of PC and MOD powder at 750 °C for 2h is 6.7 and 1.5m2/g, respectively. The specific surface area of powder prepared by conventional solid-state reaction is quite low, typically less than 1.5m2/g. Therefore, the feasibility of the polymerizable complex route is demonstrated in the powder synthesis of SBT with large surface area.
MAGNETIC AND ELECTRONIC TRANSPORT PROPERTIES OF NANOSTRUCTURED La0.67Ca0.33MnO3 FILMS
Authors: LI P. G. , CHEN C. P. , ZHANG Y. , FU X. L. , CHEN L. M. , LI L. H. , TANG W. H.
Published: August 2005

Nanostructured colossal magnetoresistive (CMR) films of La 0.67 Ca 0.33 MnO 3 (LCMO) were deposited by using pulsed electron deposition technique on anodized aluminum oxide membranes with pores of 50 nm in diameter. The magnetic and electronic transport properties were measured on Quantum Design physics properties measurement system (PPMS) and magnetic properties measurement system (MPMS). The resistance peak temperature ( T P ) is about 165 K and the Curie temperature ( T C ) is about 260 K. Large magnetoresistance was observed near T P in these nanostructured LCMO films. Linear I-V curves at different temperatures indicate no electronic tunneling effect. The large difference between T P and T C suggests that the nature of the resistance peak is different from that of bulk samples. The physics in these nanostructured films should be interesting to explore the mechanism of CMR effect.
INFLUENCE OF BIQUADRATIC INTERACTION IN THE NANO-SCALED FIBONACCI MAGNETIC MULTILAYERS
Authors: CAI H. L. , JIANG S. S. , SHENG W. T. , YANG L. , DU J.
Published: August 2005

The magnetization of the magnetic multilayers with Fibonacci sequence was studied theoretically. By considering the Zeeman, magnetic anisotropy, bilinear and biquadratic exchange energies in the multiplayer system, the angles of the magnetization between all magnetic layers were calculated numerically by minimizing the magnetic energy. The magnetization curves and hysteresis loops were obtained. By considering the different strengths of biquadratic interaction between the magnetic layers some novel phenomena appears. The magnetization in magnetic sub-layers may rotates reversibly or irreversibly by magnetic field.
EXCHANGE BIAS AND ANGULAR DEPENDENCE IN Co/Co3O4 BILAYERS
Authors: WANG YA-XIN , YOU BIAO , TIAN WEI , WANG YI-XING , SUN LIANG , LU MU , LI QI
Published: August 2005

Co/Co 3 O 4 bilayers were fabricated by magnetron sputtering with Co and Co 3 O 4 targets. The exchange bias effect was observed at 80K, which was much higher than the N• el temperature of Co 3 O 4 (about 40K). X-ray photoelectron spectroscopy results showed that CoO was formed near the Co/Co 3 O 4 interface, probably due to diffusion of oxygen atoms. The angular dependence of exchange coupling in Co/Co 3 O 4 bilayers could not be satisfied with simple cosine function, and the position of the maximum of exchange bias departed from the FM easy axis. The mechanism including rotatable anisotropy and movement of domain wall in AF was used to explain the experiment results.
A NEW GRIDLESS ION OPTICS FOR HIGH RESOLUTION TIME-OF-FLIGHT MASS SPECTROMETER
Authors: BHOWMICK A. , CARVALHO W. C. J. , KORGAONKAR A. V. , YAKHMI J. V. , SAHNI V. C.
Published: August 2005

Wire meshes commonly used as transmission grids in ion optical configurations has certain unavoidable disadvantages. Apart from the loss in transmission, there are small angle deflections while the ions are passing close to the wires. This is important for high resolution time-of-flight mass spectrometry as this effect impairs both the dynamic range and the resolution. The amount of deflection from various commercially available grids are determined from simulation calculations on representative wire grids. Gridless designs of ion optics are becoming more popular in recent times for sophisticated and sensitive measurements. Here we report such a device for time of flight mass spectrometer that also assists in perpendicular ionization. This ion optics together with a gridless ion reflector gives a high time resolution of more than 40000.
EFFECT OF ANNEALING TEMPERATURE OF CERIUM OXIDE NANOPARTICLES STUDIED BY SMALL-ANGLE X-RAY SCATTERING
Authors: JU X. , RONG L. X. , ZHANG J. , DONG B. Z.
Published: August 2005

The evolution of microstructure of cerium oxide nanoparticles prepared in a sol-gel process was investigated by small-angle X-ray scattering (SAXS) measurements, in which the range of annealing temperature was from 298 K to 973 K in air. It was found that their scattering intensities increased dramatically and was proportional to h-a as the temperature went up to 873 K. Meanwhile, the average radius of gyration Rg, increased. This suggested that these cerium oxide nanoparticles have self-similar structure behavior or mass fractal structure. When the temperature was higher than 873 K, the feature of the SAXS spectra became identical to that of the sactterers with surface fractal structure rather than the mass fractal structure.
DEPOSITION AND CHARACTERIZATION OF SEVERAL-LAYER Pb CLUSTER FILMS
Authors: SONG FENGQI , LI ZHENLIN , HONG JIANMING , ZHANG LU , HAN MIN
Published: August 2005

The surface morphology of low-energy deposited Pb cluster films was characterized by TEM observation. The free clusters before arrival on the substrates were considered as liquid droplets and a cooling time was assumed to interpret the final morphology by DDA (deposition-diffusion-aggregation) model. The island radius is related to the cluster beam flux, effective diffusion radius and the cooling time. There appeared a viscous net instead of neck-connections and islands when several layers were deposited. After as-prepared samples were exposed to air, an oxide coating, i.e. a core/shell structure, was formed and it could prevent the Pb core from full oxidation.
THERMAL DYNAMICS OF Te CLUSTER FILM AT ANNEALING PROCESSES
Authors: HONG KUNQUAN , MA LI , CHEN PINGPING , SHEN WEIFENG , WANG GUANGHOU
Published: August 2005

We report a novel experimental finding of Te cluster films with fractal structure formed at annealing process and the Monte-Carlo simulation of this process. Te cluster films were prepared by using inert gas condensation method and annealed the sample in situ at 523K under TEM. The fractal patterns were formed because of evaporation when the substrate temperature increased. The simulation results indicate that the morphology of the nanofilm is not changed at first, but with increasing temperature some cavities appear due to evaporation. With further increasing temperature, those cavities are enlarged, then networks, fractal patterns and islands are formed subsequently. The turning point of temperature, at which the system has the fastest evaporating rate, is also obtained. It is predicated that the nanostructural films with special pattern and novel property can be achieved by annealing the cluster film in a controlled manner.
THE INFLUENCE OF STRUCTURE IMPERFECTION ON THE GLASS-TRANSITION BEHAVIOR IN C60 FILMS
Authors: WU JIAN , GUI MIN , BAO PENG , FENG DUAN , YANG SENZU
Published: August 2005

Two batches of C 60 films were grown at different growth rate, using a vacuum deposition technique. X-ray diffraction patterns indicate both films have preferential (111) orientation. We measured their dielectric constant and loss factor from 80K to room temperature, and observed distinct broad and asymmetric loss peaks, attributed to orientational glass transition. The apparent activation energy was determined as 344.4 and 304.8 meV for film A and B respectively, larger than the value 280 meV in bulk C 60. Ngai's correlated-state model is used to simulate relaxation spectrum, and the real activation energies were calculated, which agree with the reported activation value in bulk C 60 very well. We propose that the structure imperfection have contributed additional dipole correlation interactions, which make the relaxation behavior of our C 60 films deviate from that of bulk C 60.
THERMODYNAMICAL PROPERTIES OF SODIUM MICROCLUSTERS
Authors: ZHANG F. S. , WANG F.
Published: August 2005

Isomerization, pseudo-rotation and phase transition in sodium microclusters Nan are investigated for several sizes ( n =4, 8, and 20) using distance dependent tight-binding molecular dynamics simulations with a particular attention to Na4.
ORTHORHOMBIC-TO-TETRAGONAL PHASE TRANSITION IN 6.8-nmPbTiO3 NANOPARTICLES
Authors: DENG Y. , ZHANG M. S. , WANG J. L. , GU Q. R.
Published: August 2005

Crystalline 6.8-nm PbTiO 3 (PT) nanoparticles were prepared through a modified solgel method. The samples showed high homogeneity and in orthorhombic phase. We examined the structural and phonon characteristics in PT nanoparticles with various grain sizes, finding that the orthorhombic phase begins to emerge at room temperature when particle size reduces to 11 nm. In the 6.8-nm PT nanoparticles, an orthorhombic-to-tetragonal phase transition at 190°C was detected by recording the Raman spectra as a function of temperature. The thermal properties of PT nanocrystals were also studied, demonstrating that the orthorhombic-to-tetragonal phase transition in the 6.8-nm PT nanoparticles is a second-order phase transition with continuous change in lattice parameter.
COMPARISON OF INTERFACE AND STRUCTURE IN NiO-PINNING SPIN VALVES
Authors: SUN L. , DU J. , CHEN Z. R. , REN Y. , ZHANG A. M. , SHENG W. T. , ZHANG W. , YOU B. , LU M. , HU A. , ZHOU S. M.
Published: August 2005

Top and bottom NiO -pinning spin valves, e.g. Ta/NiO/Co/Cu/Co/Ta and Ta/Co/Cu/Co/NiO/Ta multilayers, were investigated extensively. At the same thickness of the Cu layer, the GMR ratio for the bottom one is about 30% larger than that for the top one, which is unambiguously due to the roughness effect at the NiO/Co interface. The roughness of NiO/Co interface of the top NiO -pinning spin valve is much larger than that of the bottom one, which may be due to the deposition sequence. On the other hand, although the preferred orientation of the top NiO -pinning spin valve is more prominent than that of the bottom one, it seems not favorable to the specular reflection effect.
THERMAL EVAPORATION SYNTHESIS OF ZnO MICROSHELLS
Authors: XING Y. J. , YU D. P. , XI Z. H. , XUE Z. Q.
Published: August 2005

We demonstrate the synthesis of zinc oxide microshells by thermal evaporation of ZnO and Zn powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) observations reveal that the products are ZnO microshells with hollow cores, of which the wall thickness is about several hundred nanometers. The possible growth process is discussed.
ROOM TEMPERATURE SELF-ASSEMBLY GROWTH OF COBALT NANOWIRES UNDER MAGNETIC FIELDS
Authors: JIA YAOSHUN , CHEN QIANWANG , WU MINGZAI
Published: August 2005

Polycrystalline cobalt nanowires, with average diameter of 80 nm and length about 10 μm, were synthesized in the hydrazine hydrate solution at room temperature under magnetic fields. A seed-mediated growth approach was applied. Magnetic fields induced the growth of nanowires via aligned self-assembly of cobalt nanocrystallites. Magnetic measurements showed that the saturation magnetization (Ms) of the cobalt nanowires synthesized under magnetic field was five times larger than that of the samples prepared without magnetic fields; while the coercivity (Hc) of the sample prepared under magnetic fields was half of that of the sample synthesized without magnetic fields. The reasons for the magnetism changes were discussed.
PREPARATION AND MICROSTRUCTURE CHARACTERIZATION OF BORON NITRIDE NANOCRYSTALS FROM AQUEOUS SOLUTIONS
Authors: ZHAN JIE , HAO XIAOPENG , JIANG MINHUA , WEN SHULIN
Published: August 2005

Boron nitride nanocrystals have been prepared in a hydrothermal route. The crystalline phases have been identified as cubic boron nitride (cBN) and orthorhombic (oBN) by XRD and FTIR. Further evidences for the formation of cBN have been obtained from microanalysis and composition identification by HRTEM, SAED and EDS.
SELF-ASSEMBLY OF SILVER NANOCLUSTERS ON TRIBLOCK COPOLYMER TEMPLATES
Authors: SHI ZHONG-TAO , HAN MIN , ZHAO SHI-FENG , ZHANG LU , LI XUE-FEI , WAN JIAN-GUO , WANG GUANG-HOU
Published: August 2005

Poly (styrene-b-butadiene-b-styrene) (SBS) triblock copolymer templates have been prepared by solvent-induced order-disorder phase transition method. Silver nanoclusters have been deposited onto the SBS copolymer templates by low energy clusters beam deposition (LECBD) method. The microstructures of the template and cluster deposits have been characterized by AFM with tapping-mode. It is shown that the triblock copolymers are self-assembled to form an in-plane cylinder ordered microstructure. In the case of low coverage (<50%), silver nanaoclusters deposited on the template tend to aggregate along with the pattern of the template and coalesce into larger nanoparticles. Optical absorption spectra reveal that the surface plasmon resonance (SPR) of silver nanoclusters deposited on the template occurs at 545nm, being a red shift of ~75nm compared to that silver nanoclusters deposited on the fused quartz substrate.
BAND LIKE ELECTRONIC STRUCTURES IN SQUARE HOLLOW QUANTUM DOTS BY 3D-MHFKS CALCULATION
Authors: TAKIZAWA TOKIHIRO , OKADA HOSHIHITO , MATSUSE TAKEHIRO
Published: August 2005

To find novel aspects of the electronic structures in quantum dots (QD) from a view point of spatial broken symmetry, 3-dimensional-mesh Hartree-Fock-Kohn-Sham (3D-MHFKS) calculations1 are applied to the interacting electron system of electron number N in a symmetry broken hollow QD. For the case of a square hollow quantum dot confined in square hard wall (HW) potential (SSHQD), the magnetic ( B ) field dependence of the obtained single particle energy levels and chemical potentials in B-N diagram are shown to have a band like electronic structures over the wide B -field range up to 20T. To clarify the origin of the band like electronic structures in SSHQD, 3D-MHFKS calculations are also applied for the mixed symmetry QD's with a circular hollow in square HW potential (SCHQD) and with a square hollow in circular HW potential (CSHQD).
STRUCTURAL AND OPTICAL CHARACTERIZATION OF ZnO SINGLE CRYSTALLINE NANOBAMBOOS
Authors: MIAO LEI , TANEMURA SAKAE , HAYASHI YASUHIKO , TANEMURA MASAKI , WANG RONGPING , TOH SHOICHI , KANEKO KANEKO
Published: August 2005

ZnO nanobamboos and nanowires with diameters of 10–30 nm and lengths of 2–4 μm have been prepared by laser ablation in vacuum with precisely controlled pressure, growth and post-annealing temperature. XRD results show the annealed sample is hexagonal ZnO . Low-magnified TEM observation reveals the annealed sample includes ZnO nanobamboos and nanowires. High resolution TEM image and electron diffraction pattern confirm that the structure of ZnO nanobamboo is regular stacking of Zn and O layers with high crystal quality. The growth direction is determined as along [001] direction (c axis). TEM observations confirm that the formation of bamboo-shape ZnO is due to the stacking fault and cleavage. The bundle of those stacking faults seems to be the origin of the black contrast at the nodes. The uniformity of chemical composition for the nanobamboos is identified by EDS profiles. A strong-narrow UV band centred at 390 nm and a weak-broad green band centred at 515 nm are observed at room temperature in the PL spectrum recorded from the annealed ZnO nanobamboos and nanowires.
PREPARATION OF SnO2 NANOWIRES SYNTHESIZED BY VAPOR-SOLID MODE AND ITS GROWTH MECHANISM
Authors: ZHENG CHANGLIN , WAN JIANGUO , CHENG YAO , GU DONGHUA , ZHAN YONGJIE
Published: August 2005

Single crystal SnO2 nanowires with diameters of 20 ~ 100nm have fabricated by the reaction of vapor SnO with the oxygen. Vapor-Solid (VS) mechanism is applied to explain to the growth process. Scan electron microscopy (SEM), Transmission electron microscopy (TEM), Selected area diffraction (SAED) and High resolution transmission electron microscopy (HRTEM) studies show that the SnO2 nanowires grow along [100] or [010] orientation, which is not in agreement with the symmetry of SnO2 crystal structure. We prove that the low vapor saturation is the key growth condition of the SnO2 nanowires which prevents the two dimensional nucleation on the side faces and causes one dimensional large aspect ratio.
STRONG LUMINESCING CdSe NANOPARTICLES BY SURFACE MODIFICATION WITH CADMIUM (II) HYDROUS OXIDE
Authors: ZHOU XINGPING , KOBAYASHI YOSHIO , OHUCHI NORIAKI , TAKETA MOTOHIRO , KASUYA ATSUO
Published: August 2005

CdSe nanoparticles were prepared by simply mixing Na 2 SSeO 3 solution with CdSO 4 solution under [ Cd 2+]/[ Se 2-] ( Cd/Se ) ratio of 1.2 at room temperature. The nanoparticles had an average size of 2.3 nm and showed fairly strong photoluminescence (PL) with a peak at 539 nm. Deposition of cadmium (II) hydrous oxide on the CdSe nanoparticles increased photoluminescence quantum yield from 3.1 to 34.8%, in comparison to Rhodamine 6G aqueous solution. Both of the CdSe nanoparticles and the cadmium (II) hydrous oxide deposited on CdSe nanoparticles were characterized as of cubic structure from XRD data and the electron diffraction (ED) patterns. Also, the reason for the photoluminescence enhancement was simply elucidated.
GROWTH MECHANISM OF COILED CARBON WHISKERS
Authors: GUO DINGHE , GUO ZHANGBO , FAN XIANGJUN
Published: August 2005

The growth mechanism of coiled carbon whiskers was thoroughly studied. The carbon whiskers were prepared by chemical vapor deposition (CVD) at high temperature (500-650 °C) using acetylene as the carbon source and metal powder as the catalyst. The results show that the shape, diameter and pitch of the coiled carbon whiskers are dependent on the particle size of metal powder: when the sizes of metal powder particles are in the range of tens of microns, carbon whiskers have twisted string shape with diameters between 130 nm and 180 nm and a pitch of 100 to 350 nm. When the diameters of metal powder particles are about several hundred microns, tube shape of carbon whiskers with diameters between 280nm and 350 nm and a pitch between 150nm and 180nm are obtained. The range of temperature for the preparation of coiled carbon whiskers by the CVD method follows Quasi-VLS theory.
NUMERICAL CALCULATIONS OF AC RESPONSE IN AHARONOV-BOHM RINGS
Authors: HE SHUN , JIN GUOJUN , ZHAO XUEAN , MA YUQIANG
Published: August 2005

We present a detailed theoretical investigation on the transport properties of the one dimensional quantum rings. The Aharonov-Bohm effects under the low-voltage and low-frequency perturbation have been carefully studied. Scattering matrix method is adopted to obtain the ac response at external perturbation. The results show that the dc and ac parts of the conductance are dependent on the incident electron energy, magnetic field strength, and the coupling parameter. Some impressive characteristics of the emittance have also been discussed.
ELECTRON TRANSPORT IN MULTIPLY CONNECTED AHARONOV-BOHM RINGS
Authors: CUI WANYIN , JIN GUOJUN
Published: August 2005

We investigate the transmission coefficient and persistent current of periodically arranged Aharonov-Bohm rings coupled to external leads. A general theory of quantum waveguide based on the transfer matrix method is developed and is used to study one-dimensional periodic ring structures. A precise expression for the transmission coefficient is derived. The results show that in the contacted ring case the conduction band electrons give rise to periodically arranged persistent currents in the structure, while the band gap electrons can cause giant persistent currents in the first few loops. We also observe isolated transmission peaks in the periodically arranged rings connected via leads.
IONIZATION OFNa2BY HIGHLY CHARGED PARTICLES
Authors: WEI B. R. , ZHANG F. S. , CHENG W. , YAN S. W. , XIE B. S.
Published: August 2005

Based on the time dependent of local density approximation method, the processes of excitation of sodium clusters by swift highly charged C6+, C4+, C2+, and C+are studied. The time dependent probabilities of escaped electrons are obtained and the ionization probabilities of the Na2are deduced. One finds that, the cluster is strongly ionized by C6+, and there is only a weak ionization by C+.
PROJECTILE ENERGY LOSS IN ION-C60 COLLISIONS
Authors: CHEN L. , WEI B. , BREDY R. , BERNARD J. , MARTIN S.
Published: August 2005

In highly charged ion Xe q+ ( q =8, 15, 20, 25, 30) on C 60 collisions ( v = 0.19 a.u. ), the energy loss of projectiles in frontal collisions has been measured by analyzing the kinetic energy of scattered ions. Using singly charged projectiles He +, the measurement of the ejected electron number provides information on the electronic energy deposition during the fontal collision on the C 60 target.
DNA CURVATURE OF (CCTG)n · (CAGG)n AND (ATTCT)n · (AGAAT)n REPEATS SEQUENCES
Authors: CAI Lu
Published: August 2005

A statistical mechanical model was used to calculate the curvature of the 5 chemically synthesized DNAs which contain repeats sequences ( CCTG )n · ( CAGG )n and ( ATTCT )n · ( AGAAT )n associated with human diseases. 8% polyacrylamide gel analyses were also performed for these 5 DNAs. The results indicate the curvature of the sequences CCTG/bend and ATTCT/bend are larger than that of the sequences CCTG/straight and ATTCT/straight. The curvature of straight/bend is larger than that of CCTG/straight and ATTCT/straight, and smaller than that of CCTG/bend and ATTCT/bend. There exists good consistent between theoretical prediction and experimental data.
THEORETICAL STUDY ON SURVIVING FRACTION FOR V79 CELLS IRRADIATED BY 40KeV/μm DEUTERON ION: A CASE OF CLUSTERING DAMAGES
Authors: MA YUN-ZHI , ZHOU HONG-YU , ZHUO YI-ZHONG
Published: August 2005

A model based on the concept of clustering damages has been proposed to relate dose absorbed by cell population to the initial biological damages. The key input is the size distribution of ionization clusters formed by ionizing radiation in 3nm diameter sphere (nucleotide) and 10nm diameter sphere (nucleosome) calculated by detailed Monte Carlo simulation code. The clustering damage based model also includes particular bio-geometrical information of cell at different cell cycle point. Some experimental and empirical data were used to transform the ionization cluster size distribution into lethal and potentially lethal cross sections (cell-1Gy-1), which are just the input of Lethal and Potentially Lethal (LPL) model. The model enables us to calculate the average number of fatal lesions at long time after irradiation and then surviving probability at different dose level and dose rate for specific kind of radiation characterized by cluster size distribution. To test the model, the surviving curves of V79 cell line at G1 phase and S phase irradiated by 40keV/μm deuteron ion were calculated and acceptable results were obtained.
Hepatic insulin gene therapy prevents deterioration of vascular function and improves adipocytokine profile in STZ-diabetic rats
Authors: Thulé Peter M. , Campbell Adam G. , Kleinhenz Dean J. , Olson Darin E. , Boutwell Joshua J. , Sutliff Roy L. , Hart C. Michael
Published: August 2005

Hepatic insulin gene therapy (HIGT) ameliorates hyperglycemia in diabetic rodents, suggesting that similar approaches may eventually provide a means to improve treatment of diabetes mellitus. However, whether the metabolic and hormonal changes produced by HIGT benefit vascular function remains unclear. The impact of HIGT on endothelium-dependent vasodilation, nitrosyl-hemoglobin content (NO-Hb), and insulin sensitivity were studied using aortic ring preparations, electron spin resonance spectroscopy (ESR), homeostasis assessment of insulin resistance (HOMA-IR) calculations, and insulin tolerance testing (ITT). Data were correlated with selected hormone and adipocytokine concentrations. Rats made diabetic with streptozotocin were treated with subcutaneous insulin pellets dosed to sustain body weights and hyperglycemia or with HIGT; nondiabetic rats served as controls. Hyperglycemic rats demonstrated impaired endothelium-dependent vasodilation, reduced levels of NO-Hb, and diminished insulin, leptin, and adiponectin concentrations compared with controls. In contrast, HIGT treatment significantly reduced blood sugars and sustained both endothelium-mediated vasodilation and NO-Hb at control levels. HOMA-IR calculations and ITT indicated enhanced insulin sensitivity among HIGT-treated rats. HIGT partially restored suppressed leptin levels in hyperglycemic rats and increased adiponectin concentrations to supranormal levels, consistent with indicators of insulin sensitivity. Our findings indicate that the metabolic milieu produced by HIGT is sufficient to preserve vascular function in diabetic rodents. These data suggest that improved glycemia, induction of a beneficial adipocytokine profile, and enhanced insulin sensitivity combine to preserve endothelium-dependent vascular function in HIGT-treated diabetic rats. Consequently, HIGT may represent a novel and efficacious approach to reduce diabetes-associated vascular dysfunction.
Adhesion Molecule Expression in Fibroblasts
Authors: Chen Kui , Chen Jiawei , Liu Yong , Xie Jin , Li Dayuan , Sawamura Tatsuya , Hermonat Paul L. , Mehta Jawahar L.
Published: August 2005

The endothelial lectinlike, oxidatively (ox-) modified LDL receptor LOX-1 is a critical player in the pathogenesis of atherosclerosis and myocardial ischemia. Ox-LDL binding of LOX-1 results in the expression of various adhesion molecules, which attract monocytes to endothelial cells, an initial step in atherogenesis. We wished to examine the role of the ox-LDL/LOX-1 signaling pathway in fibroblasts, which naturally express low levels of LOX-1. Rat cardiac fibroblasts were transfected with either cytomegalovirus (CMV)-LOX-1
wt
(amino acids [aa] 1 to 273) or CMV-LOX-1
1-261
(an ox-LDL–binding negative mutant, aa 1 to 261) plasmid. Western blots showed that LOX-1 protein expression was increased significantly in cells transfected with CMV-LOX-1
wt
or CMV-LOX-1
1-261
plasmid (
P
<0.01 vs control). Fibroblasts transfected with CMV-LOX-1
wt
showed ox-LDL binding, whereas fibroblasts without transfection and those transfected with CMV-LOX-1
1-261
did not bind ox-LDL. Compared with untransfected cells, ox-LDL treatment (50 μg/mL, 24 hours) markedly induced the expression of the leukocyte adhesion molecules intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM)-1 as well as matrix metalloproteinase (MMP)-1 in cells transfected with CMV-LOX-1
wt
(
P
<0.05) but not in cells transfected with CMV-LOX-1
1-261
. Concurrently, ox-LDL treatment enhanced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) (
P
<0.05 vs control) in CMV-LOX-1
wt
–transfected cells. These data suggest that in cardiac fibroblasts, ox-LDL binds to LOX-1 and activates p38 MAPK, followed by the expression of ICAM-1, VCAM-1, and MMP-1. Thus, fibroblasts transform into an endothelial phenotype on transfection with CMV-LOX-1
wt
and subsequent exposure to ox-LDL. This study provides a useful model system (plasmid-transfected fibroblasts) to study the molecular biology of LOX-1.
Impaired Ca
2+
Signaling Attenuates P2X Receptor–Mediated Vasoconstriction of Afferent Arterioles in Angiotensin II Hypertension
Authors: Zhao Xueying , Cook Anthony K. , Field Mary , Edwards Brentan , Zhang Shali , Zhang Zhanying , Pollock Jennifer S. , Imig John D. , Inscho Edward W.
Published: August 2005

This study tested the hypothesis that afferent arteriolar responses to purinoceptor activation are attenuated, and Ca
2+
signaling mechanisms are responsible for the blunted preglomerular vascular reactivity in angiotensin II (Ang II) hypertension. Experiments determined the effects of ATP, the P2X
1
agonist β,γ–methylene ATP or the P2Y agonist UTP on arteriolar diameter using the juxtamedullary nephron technique and on renal myocyte intracellular Ca
2+
concentration ([Ca
2+
]
i
) using single cell fluorescence microscopy. Six or 13 days of Ang II infusion significantly attenuated the vasoconstrictor responses to ATP and β,γ–methylene ATP (
P
<0.05). During exposure to ATP (1, 10, and 100 μmol/L), afferent diameter declined by 17±2%, 29±3%, and 30±2% in normal control rats and 8±3%, 7±3%, and 22±3% in kidneys of Ang II–infused rats (13 days). Renal myocyte intracellular calcium responses to ATP or β,γ–methylene ATP were also decreased in Ang II hypertensive rats. In myocytes of control rats, peak increases in [Ca
2+
]
i
averaged 107±21, 170±38, and 478±79 nmol/L at ATP concentrations of 1, 10, and 100 μmol/L, respectively. Ang II infusion for 13 days decreased the peak responses to ATP (1, 10, and 100 μmol/L) to 65±13, 102±20, and 367±73 nmol/L, respectively. The peak increases in [Ca
2+
]
i
in response to β,γ–methylene ATP were also reduced in Ang II hypertensive rats. However, angiotensin hypertension did not change the UTP-mediated vasoconstrictor responses or the myocyte calcium responses to UTP. These results indicate that the impaired autoregulatory response observed in Ang II–dependent hypertension can be attributed to impairment of P2X
1
receptor–mediated signal transduction.
Cardiovascular Morbidity and Mortality in Hypertensive Patients With Lower Versus Higher Risk
Authors: Franklin Stanley S. , Wachtell Kristian , Papademetriou Vasilios , Olsen Michael H. , Devereux Richard B. , Fyhrquist Frej , Ibsen Hans , Kjeldsen Sverre E. , Dahlöf Björn
Published: August 2005

We hypothesized that losartan was superior to atenolol in reducing cardiovascular events in a lower-risk group (LRG) versus a higher-risk group (HRG) of patients in a Losartan Intervention For Endpoint reduction (LIFE) substudy, independently of blood pressure (BP) reduction. In a post hoc analysis, we designated 4282 patients as LRG on the basis of: (1) no previous cardiovascular disease (coronary, cerebral, peripheral vascular disease); (2) no diabetes; (3) no isolated systolic hypertension; and (4) inclusion of the lowest 3 quartiles of electrocardiographically documented left ventricular hypertrophy. The HRG consisted of 4911 remaining patients who did not qualify for the LRG. In the LRG, losartan was superior to atenolol in reducing stroke: hazard ratio (HR), 0.72 (95% confidence interval [CI], 0.53 to 0.98); new-onset diabetes (HR, 0.74 [95% CI, 0.58 to 0.93]; and new-onset atrial fibrillation: HR, 0.69 (95% CI, 0.51 to 0.92), all
P
<0.05 but not composite end points or cardiovascular mortality (both
P
=NS). In the HRG, losartan was superior to atenolol in reducing composite end points: HR, 0.82 (95% CI, 0.71 to 0.94),
P
<0.01; cardiovascular mortality: HR, 0.77 (95% CI, 0.62 to 0.95),
P
<0.05; stroke: HR, 0.75 (95% CI, 0.61 to 0.92),
P
<0.01; new-onset diabetes: HR, 0.76 (95% CI, 0.60 to 0.96),
P
<0.05; and new-onset atrial fibrillation: HR, 0.71 (95% CI, 0.58 to 88),
P
<0.05. Test for interaction of treatment with LRG versus HRG was not significant for composite end point, stroke, or atrial fibrillation, but was for cardiovascular mortality (
P
=0.018). Achieved systolic BP reduction favored losartan over atenolol by −1.8 mm Hg in LRG (
P
=NS) and −0.7 mm Hg (
P
=0.001) in HRG, but no significant differences occurred in diastolic or mean BP in either group. In conclusion, losartan compared with atenolol reduces the risk of stroke, new-onset diabetes, and new-onset atrial fibrillation in the LRG and the HRG.
A Noninferiority Comparison of Valsartan/Hydrochlorothiazide Combination Versus Amlodipine in Black Hypertensives
Authors: Weir Matthew R. , Ferdinand Keith C. , Flack John M. , Jamerson Kenneth A. , Daley William , Zelenkofske Steven
Published: August 2005

The objective of the study was to demonstrate that reduction in mean 24-hour diastolic blood pressure with 160 mg valsartan and 12.5 mg hydrochlorothiazide was not inferior to 10 mg amlodipine in hypertensive blacks. A total of 482 blacks with stage 1 and stage 2 hypertension (mean seated blood pressure 140 to 180/90 to 110 mm Hg) were enrolled in a double-blind, randomized, prospective study. After a placebo run-in period, patients were randomized to 160 mg valsartan or 5 mg amlodipine for 2 weeks, then force-titrated to 160 mg valsartan and 12.5 mg hydrochlorothiazide or 10 mg amlodipine for an additional 10 weeks. Blood pressure was assessed by 24-hour ambulatory blood pressure monitoring. Other assessments included quality of life, peripheral edema, and safety. Noninferiority of valsartan/hydrochlorothiazide to amlodipine was demonstrated by comparable reductions in mean 24-hour diastolic blood pressure with both treatments (−10.2±8.6 mm Hg versus −9.1±8.3 mm Hg, respectively;
P
<0.001 for noninferiority), as well as in mean 24-hour systolic blood pressure (−15.9±12.1 mm Hg versus −14.5±12.2 mm Hg;
P
<0.001 for noninferiority). The proportion of patients reporting adverse events and the incidence of most events were similar in both treatment groups, although more patients treated with amlodipine reported peripheral edema (5.8% versus 1.7%;
P
=0.03) and joint swelling (2.9% versus 0%;
P
=0.008) compared with valsartan/hydrochlorothiazide. We conclude that a starting dose of valsartan/hydrochlorothiazide (160/12.5 mg) is as effective as high-dose amlodipine (10 mg) in reducing blood pressure in blacks with stage 1 and stage 2 hypertension, and valsartan/hydrochlorothiazide is better tolerated.
Decreased Expression of Maxi-K
+
Channel β
1
-Subunit and Altered Vasoregulation in Hypoxia
Authors: Navarro-Antolín Javier , Levitsky Konstantin L. , Calderón Eva , Ordóñez Antonio , López-Barneo José
Published: August 2005

Background—

Hypertension, a major cause of cardiovascular morbidity and mortality, can result from chronic hypoxia; however, the pathogenesis of this disorder is unknown. We hypothesized that downregulation of the maxi-K
+
channel β
1
-subunit by hypoxia decreases the ability of these channels to hyperpolarize arterial smooth muscle cells, thus favoring vasoconstriction and hypertension.

Methods and Results—

Lowering O
2
tension produced a decrease of maxi-K
+
β
1
-subunit mRNA levels in rat (aortic and basilar) and human (mammary) arterial myocytes. This was paralleled by a reduction of the β
1
-subunit protein level as determined by immunocytochemistry and flow cytometry. Exposure to hypoxia also produced a decrease of open probability, mean open time, and sensitivity to the xenoestrogen tamoxifen of single maxi-K
+
channels recorded from patch-clamped dispersed myocytes. The number of channels per patch and the single-channel conductance were not altered. The vasorelaxing force of maxi-K
+
channels was diminished in rat and human arterial rings exposed to low oxygen tension.

Conclusions—

These results indicate that a decrease of the maxi-K
+
channel β
1
-subunit expression in arterial myocytes is a key factor in the vasomotor alterations induced by hypoxia.
Clinical Features and Outcomes of Childhood Hypertrophic Cardiomyopathy
Authors: Nugent Alan W. , Daubeney Piers E.F. , Chondros Patty , Carlin John B. , Colan Steven D. , Cheung Michael , Davis Andrew M. , Chow C.W. , Weintraub Robert G.
Published: August 2005

Background—

Population-based studies have provided insight into the natural history of adult hypertrophic cardiomyopathy, but comparable information for affected children is lacking.

Methods and Results—

All Australian children who presented with primary cardiomyopathy at 0 to 10 years of age between January 1, 1987, and December 31, 1996, were enrolled in a longitudinal cohort study. A single cardiologist reviewed serial cardiac investigations on each subject. A total of 80 subjects with hypertrophic cardiomyopathy were identified. An underlying syndromal, genetic, or metabolic condition was identified in 46 subjects (57.5%). There were no cases of sudden death at presentation. Left ventricular outflow tract obstruction was present in 32 subjects (40%); right ventricular outflow obstruction was present in 10 (12.5%). Freedom from death or transplantation was 83% (95% CI, 73 to 90) 5 years after presentation and 76% (95% CI, 62 to 86) 10 years after presentation. By proportional-hazards regression analysis, risk factors for death or transplantation included concentric left ventricular hypertrophy, age at presentation <1 year, lower initial fractional shortening Z score, and increasing left ventricular posterior wall thickness relative to body surface area. At the latest follow-up, 54 of 65 surviving subjects had no symptoms, and 46 were receiving no regular medication.

Conclusions—

Syndromal, genetic, and metabolic causes predominate in children with hypertrophic cardiomyopathy. Ventricular outflow tract obstruction is common. The clinical status of long-term survivors is good. This population-based study identifies children with hypertrophic cardiomyopathy who are at risk of adverse events.
Interruptions of Chest Compressions During Emergency Medical Systems Resuscitation
Authors: Valenzuela Terence D. , Kern Karl B. , Clark Lani L. , Berg Robert A. , Berg Marc D. , Berg David D. , Hilwig Ronald W. , Otto Charles W. , Newburn Daniel , Ewy Gordon A.
Published: August 2005

Background—

Survival after nontraumatic out-of-hospital (OOH) cardiac arrest in Tucson, Arizona, has been flat at 6% (121/2177) for the decade 1992 to 2001. We hypothesized that interruptions of chest compressions occur commonly and for substantial periods during treatment of OOH cardiac arrest and could be contributing to the lack of improvement in resuscitation outcome.

Methods and Results—

Sixty-one adult OOH cardiac arrest patients treated by automated external defibrillator (AED)–equipped Tucson Fire Department first responders from November 2001 through November 2002 were retrospectively reviewed. Reviews were performed according to the code arrest record and verified with the AED printout. Validation of the methodology for determining the performance of chest compressions was done post hoc. The median time from “9-1-1” call receipt to arrival at the patient’s side was 6 minutes, 27 seconds (interquartile range [IQR, 25% to 75%], 5 minutes, 24 seconds, to 7 minutes, 34 seconds). An additional 54 seconds (IQR, 38 to 74 seconds) was noted between arrival and the first defibrillation attempt. Initial defibrillation shocks never restored a perfusing rhythm (0/21). Chest compressions were performed only 43% of the time during the resuscitation effort. Although attempting to follow the 2000 guidelines for cardiopulmonary resuscitation, chest compressions were delayed or interrupted repeatedly throughout the resuscitation effort. Survival to hospital discharge was 7%, not different from that of our historical control (4/61 versus 121/2177;
P
=0.74).

Conclusions—

Frequent interruption of chest compressions results in no circulatory support during more than half of resuscitation efforts. Such interruptions could be a major contributing factor to the continued poor outcome seen with OOH cardiac arrest.
Exploratory Data Analysis of the Multilevel Anthropogenic Zinc Cycle
Authors: Graedel T.E. , Bertram Marlen , Reck Barbara
Published: August 2005

A comprehensive multilevel contemporary cycle for stocks and flows of zinc is analyzed by the tools of exploratory data analysis. The analysis is performed at three discrete organizational levels—country (53 countries and 1 country group that together comprise essentially all anthropogenic stocks and flows of zinc), world region (9 world regions), and the planet as a whole. The results demonstrate the following: (1) Exploratory data analysis provides valuable and otherwise unobtainable information about material flows, especially those across multiple spatial levels. (2) All distributions of countrylevel zinc stock and flow data are highly skewed, a few countries having large magnitudes, many having small magnitudes. Rates of fabrication of zinc‐containing products for the countries are poorly correlated with rates of extraction, reflecting the fact that many countries that extract zinc do not fabricate products from zinc to any significant degree, and vice versa. (4) Virtually all countries are adding zinc to stock in the use phase (in galvanizing applications, zinc castings, etc.). These rates of addition are highly correlated with rates of zinc entering use in all regions, and are higher in regions under vigorous development. (5) With weak confidence, the rate of zinc landfilling by countries appears to be highly correlated with the rate of discard. (6) The statistical distributions of regional‐level zinc cycle parameters are approximately log normal. (7) The extremes of normalized statistical distributions of zinc flow values are broader at lower spatial levels (country versus region, for example), but regional interquartile ranges for zinc entering use and zinc discards are higher at regional level then at country level.