Chirality-asymmetry force between ɑ-quartz and copper block

The chirality-asymmetry macroscopic force mediated by light pseudoscalar particles between α -quartz and some achiral matter is studied. If this force between achiral source mass and α -quartz with some chirality is attractive, it will become repulsive when the chirality of the α -quartz crystal is changed. According to the tested limits of the coupling constant g_s g_p /\hbar c< 1.5× 10^-24 at the Compton wavelength λ = 10^-3 m, the force (F) between a 0.08× 0.08× 0.002 m³ block of α -quartz and a 0.08× 0.08× 0.01 m³ copper block with a separation being 0.5× 10^-3 \mbox{m} in between, is estimated from the published data at less than 4.64× 10^-24 N, i.e. F < 4.64× 10^-24 N.     

Search for fractional-charge particles in meteoritic material

We have used an automated Millikan oil drop method to search for free fractional-charge particles in a sample containing in total 3.9 mg of pulverized Allende meteorite suspended in 259 mg of mineral oil. The average diameter of the drops was 26.5 microm with the charge on about 42 500 000 drops being measured. This search was motivated by the speculation that isolatable, fractional-charge particles produced in the early Universe and present in our Solar System are more likely to be accumulated in asteroids than on Earth's surface. No evidence for fractional-charge particles was found. With 95% confidence, the concentration of particles with fractional-charge more than 0.25 e (e being the magnitude of the electron charge) from the nearest integer charge is less than 1.3 x 10(-21) particles per nucleon in the meteoritic material and less than 1.9 x 10(-23) particles per nucleon in the mineral oil.     

Solid solubility in isolated nanometer-sized alloy particles in the Sn-Pb system

The finite size effect on both the solid solubility and the thermal expansion coefficient in nanometer-sized lead particles was examined by in-situ transmission electron microscopy. The solid solubility of tin in approximately 12-nm-sized particles of lead at room temperature was evaluated be higher than 30 atomic percent, which is almost ten times higher than that in the corresponding bulk lead. The thermal expansion coefficient of lead increased from 29×10^-6 K^-1 for bulk to 38×10^-6 K^-1 when the size of particles decreased from ∞ (bulk) to 16 nanometers. The increment of the thermal expansion coefficient with decreasing size of particles suggests the reduction of the cohesive energy and therefore the reduction of the elastic modulus with decreasing size of particles. It is then considered that the suppression of the strain energy in the solid solution may be responsible for the enhanced solid solubility in nanometer-sized alloy particles.     

Thermal hysteresis of a simulated Al<Subscript>2</Subscript>O<Subscript>3</Subscript> system

Thermal hysteresis in a simulated Al₂O₃ system has been investigated using a Molecular Dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials. The system was cooled down from 7000 K to 0 K and heated up from 0 K to 7000 K by the same cooling/heating rate of 1.7178×10¹⁴ K/s. The temperature dependence of the system density upon cooling and heating shows thermal hysteresis. The differences between structure and dynamics of the models obtained by cooling (MOBC) and heating (MOBH) at three different temperatures of 2100 K, 3500 K and 5600 K have been detected. Calculations show that the differences in the dynamics of the systems are more pronounced than those in the structure. Furthermore, dynamical heterogeneities in MOBC and MOBH at the temperature of 2100 K have been studied through a non-Gaussian parameter and comparison of partial radial distribution functions (PRDFs) for the 10% most mobile or immobile particles with their corresponding mean ones. Cluster size distributions of the 10% most mobile or immobile particles in MOBC and MOBH at the temperature of 2100 K have been obtained. Calculations show that differences in dynamical heterogeneities are pronounced.     

Neutral atom frequency reference in the deep ultraviolet with fractional uncertainty = 5.7×10(-15)

We present an assessment of the (6s2) (1)S0 ? (6s6p)(3)P0 clock transition frequency in 199Hg with an uncertainty reduction of nearly 3 orders of magnitude and demonstrate an atomic quality factor Q of ～10(14). The 199Hg atoms are confined in a vertical lattice trap with light at the newly determined magic wavelength of 362.5697±0.0011 nm and at a lattice depth of 20E(R). The atoms are loaded from a single-stage magneto-optical trap with cooling light at 253.7 nm. The high Q factor is obtained with an 80 ms Rabi pulse at 265.6 nm. We find the frequency of the clock transition to be 1,128,575,290,808,162.0±6.4(syst)±0.3(stat) Hz (i.e., with fractional uncertainty=5.7×10(-15)). Neither an atom number nor second order Zeeman dependence has yet been detected. Only three laser wavelengths are used for the cooling, lattice trapping, probing, and detection.     

What are the relative roles of heating and cooling in generating solar wind temperature anisotropies?

Temperature anisotropy in the solar wind results from a combination of mechanisms of anisotropic heating (e.g., cyclotron-resonant heating and dissipation of kinetic Alfvén waves) and cooling (e.g., Chew-Goldberger-Low double-adiabatic expansion). In contrast, anisotropy-driven instabilities such as the cyclotron, mirror, and firehose instabilities limit the allowable departure of the plasma from isotropy. This study used data from the Faraday cups on the Wind spacecraft to examine scalar temperature and temperature components of protons. Plasma unstable to the mirror or firehose instability was found to be about 3-4 times hotter than stable plasma. Since anisotropy-driven instabilities are not understood to heat the plasma, these results suggest that heating processes are more effective than cooling processes at creating and maintaining proton temperature anisotropy in the solar wind.     

Numerical study of penetration and distribution of charged particles in the magnetosphere during southward IMF case

The energetic charged particles penetration in the plasmasphere are carried out using the updated version of 3D Stanford PIC code. We considered slow and fast wind streams to know the penetration of the energetic charged particles (electrons and ions) having different velocities into four regions i.e. cusp, plasmasphere, sunward, and tailward sides. It is observed that the ion penetrations are higher than electrons for solar slow wind streams in the plasmasphere, while it is reverse for the solar fast streams. Also, the results show that the percentage of penetration of the energetic charged particles (both electrons and ions) are the same into the cusp and subsolar point reconnection region. It is different for the higher speed of fast streams; so that the penetrated electrons reached about 10–20 times than penetrated ions. The results show that for the tailward reconnection region, the penetration of ions is 2–3 times higher than the penetration of electrons, but it is the same for the case of higher solar fast speed.     

Non-equilibrium cation distribution and enhanced spin disorder in hollow CoFe2O4 nanoparticles

We present magnetic properties of hollow and solid CoFe(2)O(4) nanoparticles that were obtained by annealing of Co(33)Fe(67)/CoFe(2)O(4) (core/shell) nanoparticles. Hollow nanoparticles were polycrystalline whereas the solid nanoparticles were mostly single crystal. Electronic structure studies were performed by photoemission which revealed that particles with hollow morphology have a higher degree of inversion compared to solid nanoparticles and the bulk counterpart. Electronic structure and the magnetic measurements show that particles have uncompensated spins. Quantitative comparison of saturation magnetization (M(S )), assuming bulk Néel type spin structure with cationic distribution, calculated from quantitative XPS analysis, is presented. The thickness of uncompensated spins is calculated to be significantly large for particles with hollow morphology compared to solid nanoparticles. Both morphologies show a lack of saturation up to 7 T. Moreover magnetic irreversibility exists up to 7 T of cooling fields for the entire temperature range (10-300 K). These effects are due to the large bulk anisotropy constant of CoFe(2)O(4) which is the highest among the cubic spinel ferrites. The effect of the uncompensated spins for hollow nanoparticles was investigated by cooling the sample in large fields of up to 9 T. The magnitude of horizontal shift resulting from the unidirectional anisotropy was more than three times larger than that of solid nanoparticles. As an indication signature of uncompensated spin structure, 11% vertical shift for hollow nanoparticles is observed, whereas solid nanoparticles do not show a similar shift. Deconvolution of the hysteresis response recorded at 300 K reveals the presence of a significant paramagnetic component for particles with hollow morphology which further confirms enhanced spin disorder.     

A simulation study of microstructure evolution during solidification process of liquid metal Ni

A molecular dynamics simulation study has been performed for the microstructure evolution in a liquid metal Ni system during crystallization process at two cooling rates by adopting the embedded atom method (EAM) model potential. The bond-type index method of Honeycutt--Andersen (HA) and a new cluster-type index method (CTIM-2) have been used to detect and analyse the microstructures in this system. It is demonstrated that the cooling rate plays a critical role in the microstructure evolution: below the crystallization temperature $T_{\rm c}$, the effects of cooling rate are very remarkable and can be fully displayed. At different cooling rates of $2.0\times10^{13}$\,K\,$\cdot$\,s$^{-1}$ and $1.0\times10^{12}$\,K\,$\cdot$\,s$^{-1}$, two different kinds of crystal structures are obtained in the system. The first one is the coexistence of the hcp (expressed by (12 0 0 0 6 6) in CTIM-2) and the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 and 1422 bond-types, and the hcp basic cluster becomes the dominant one with decreasing temperature, the second one is mainly the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 bond-type, and their crystallization temperatures $T_{\rm c}$ would be 1073 and 1173\,K, respectively.     

π-介子星裂探测器

负π介子和许多其他粒子不同,它们在介质中停止处有效地产生星裂,从而释放出大量的能量。我们利用了这种现象来选择性地探测负π介子。星裂探测器是个计数管望远镜。它由二个符合闪烁计数管组成。其中第一管是普通的闪烁计数管,它记录透过粒子的效率是100％。第二管的工作电压放得较低,使之只记录负π介子在晶体中引起星裂而生的大的光脉冲;它记录透过粒子的效率极低。第二管用能谱分析性能好的光电倍加管,由高稳定的电源来供应。用星裂探测器可以迅速测量负π介子的射程和能量。例如对强度为10³/秒的负π介子束,测量能量只需15分钟。这种探测器记录粒子时有选择性。它只记录星裂,而不记录其他停止的带电粒子(例如负μ介子),实验证明参看图7。我们所用的星裂探测器,对负π介子的灵敏度,比对负μ介子的灵敏度至少要大20倍。     

包括自旋轨道耦合能和作为动量函数的位能在内的汤、费模型及其在原子核中的应用

本文对于近似球对称的系统将汤、费模型推广以包括自旋轨道耦合能和作为动量和位置的函数的位能这两个因素在内。在原子核的情况下,推广的汤、费模型可以作为将布卢克勒关于核物质的理论推广到有限大原子核的一个近似的方法。本文对费米积分方程也作了相应的推广,根据推广后的费米积分方程所解出的质子的密度分布和由高能电子与原子核的散射实验所得的结果相符合。     

Measurement of the electron electric dipole moment using YbF molecules

The most sensitive measurements of the electron electric dipole moment d(e) have previously been made using heavy atoms. Heavy polar molecules offer a greater sensitivity to d(e) because the interaction energy to be measured is typically 10(3) times larger than in a heavy atom. We have used YbF to make the first measurement of this kind. Together, the large interaction energy and the strong tensor polarizability of the molecule make our experiment essentially free of the systematic errors that currently limit d(e) measurements in atoms. Our first result d(e) = (-0.2+/-3.2)x10(-26)e cm is less sensitive than the best atom measurement but is limited only by counting statistics and demonstrates the power of the method.     

Cooling antiprotons in an ion trap

The measurement of the inertial mass of the antiproton and proposed antihydrogen formation experiments require antiprotons stored in ion traps, cooled to very low (4K) temperatures. Techniques to cool the trapped antiprotons from energies around 1 keV are discussed. Coupling to an external circuit produces cooling times of order 10³ s, which may be reduced somewhat with negative feedback. Adiabatic reduction of the trapping potential produces significant cooling when the particle energies are substantially less than the well depth. Most promising is cooling via energy-transferring collisions to a cooled cloud of electrons simultaneously trapped with the antiprotons. Electron cooling times are of order 1 s, and strongly depend on electron number and density.     

The use of ultrasonic standing waves to enhance optical particle sizing equipment

Fluid dynamics modelling augmented with routines to simulate acoustic forces on aerosol particles has been used to investigate the potential of combining ultrasonic standing wave fields with optical particle analysis equipment. Simulations of particle dynamics in airstreams incorporating acoustic forces predict that particles in the 1-10 microns diameter range may be effectively focused to the velocity nodes of the standing wave field. Particles move to the velocity nodes within tens of milliseconds for acoustic frequencies of 10-100 kHz and at an acoustic energy density of 100 Jm-3. Larger particles are predicted to move to the velocity antinodes within similar times; however, there is a crossover region at approximately 15-20 microns particle diameter where longer times are predicted due to the competing forces driving particles to the vibration node and antinode. With sufficient transverse flow velocities the models predict that disturbances due to acoustic streaming can be overcome and a useful degree of focusing achieved for the aerosol particles. Results from a model demonstrating sampling and acoustic focusing of 3-9 microns aerosol particles to a 200 microns wide analysis area are presented.     

Spin polarization effect for molecule Ta2

Density functional theory （DFT） （B3p86） has been used to optimize the structure of the molecule Ta2. The result shows that the ground state of molecule Ta2 is a 7-multiple state and its electronic configuration is ^7∑u^＋, which shows the spin polarization effect for molecule Ta2 of transition metal elements for the first time. Meanwhile, spin pollution has not been found because the wavefunction of the ground state does not mix with those of higher states. So, the fact that the ground state of molecule Ta2 is a 7-multiple state indicates a spin polarization effect of molecule Ta2 of the transition metal elements, i.e. there exist 6 parallel spin electrons and the non-conjugated electrons are greatest in number. These electrons occupy different space orbitals so that the energy of molecule Ta2 is minimized. It can be concluded that the effect of parallel spin of the molecule Ta2 is larger than the effect of the conjugated molecule, which is obviously related to the effect of d-electron delocalization. In addition, the Murrell-Sorbie potential functions with parameters for the ground state ^7∑u^＋ and other states of the molecule Ta2 are derived. The dissociation energy De, equilibrium bond length Re and vibration frequency we for the ground state of molecule Ta2 are 4.5513eV, 0.2433nm and 173.06cm^-1, respectively. Its force constants f2, f3 and f4 are 1.5965×10^2aJ.nm^-2, -6.4722×10^3aJ·nm^-3 and 29.4851×10^4aJ·nm^-4, respectively. Other spectroscopic data we xe, Be and αe for the ground state of Ta2 are 0.2078cm^-1, 0.0315 cm^-1 and 0.7858×10^-4 cm^-1, respectively.     

Spin polarization effect for Os2 molecule

Density functional Theory （DFT） （B3p86） of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is ^9∑^＋g, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state ^9∑^＋g and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm^-1. Its force constants f2, f3, and f4 are 3.1032×10^2aJ·nm^-2, -14.3425×10^3aJ·nm^-3 and 50.5792×10^4aJ·nm^-4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωexe, Be and ae are 0.4277cm^- 1, 0.0307cm^- 1 and 0.6491 × 10^-4cm^-1 respectively.     

Electron state density and electron diffusion coefficient in energy space in nonideal nonequilibrium plasmas

We suggest a model for a hydrogenic low-temperature nonequilibrium nonideal plasma that allows the kinetic parameters of the plasma to be calculated by the method of molecular dynamics by taking into account the interparticle interaction. The charges interact according to Coulomb’s law; for unlike charges, the interaction is assumed to be equal to a constant at a distance smaller than several Bohr radii. For a system of particles, we solve the classical equations of motion under periodic boundary conditions. The initial conditions are specified in such a way that the electrons have a positive total energy. We consider the temperatures 1-50 K and densities n = 10⁹?10¹⁰ cm^?3 produced in an experiment through laser cooling and resonant excitation. We calculate the electron state density as a function of the plasma coupling parameter and the electron diffusion coefficient in energy space for highly excited (Rydberg) electron states close to the boundary of the discrete and continuum spectra.     

Au-BaTiO3复合薄膜的脉冲激光沉积制备及其非线性光学效应

利用脉冲激光沉积技术制备了掺杂金纳米颗粒的钛酸钡复合薄膜Au-BaTiO3,用高分辨透射电镜和X射线光电子能谱对薄膜进行了表征。从透射电镜照片可以看出,制备的样品中金颗粒大小约为2~3 nm,呈球形,均匀分布在载体介质中。X射线光电子能谱给出了Ba3d、Ti2p和Au4f电子芯能级结合能,结果表明载体介质是以BaTiO3的形式存在,而Au以金属的状态掺杂其中。330~800 nm范围的线性吸收谱表明样品中Au颗粒的共振吸收峰在500 nm附近。用单光束纵向扫描方法测量了样品的三阶非线性光学效应,使用的光源为调Q的YAG激光器,波长为532 nm,脉宽为10 ns,得到的非线性折射率和非线性吸收系数分别为-2.42×10-6esu和2.22×10-6m/W,表明了Au-BaTiO3复合薄膜有较大的非线性光学响应。     

Shell structure and pairing for interacting fermions in a trap

The shell structures for weakly interacting fermions in harmonic oscillator traps at zero temperature undergo several transitions depending on the number of particles in the trap and their interaction strength. Calculations of the one and two-particle spectra give the pairing gaps, and the many particle state is constructed by the seniority scheme. For sufficiently few particles, N less than or similar to 10(4), the pairing field exceeds the mean-field splitting of single particle levels at the Fermi surface and the greater number of almost degenerate states due to the SU(3) symmetry in the harmonic oscillator shell lead to supergaps. Deformation and rotation are also discussed.     

Ash cenosphere fragmentation during pulverised pyrite combustion: Importance of cooling

This paper as the first time in the field reports the direct experimental evidence for demonstrating the important role of cooling in ash cenosphere fragmentation using a simple but unique combustion system. The combustion system used pulverised pyrite (38–45 µm) for combustion in drop-tube furnace under designed conditions (gas temperature: 1000 °C; residence time: 1.2 s), which produced dominantly ash cenosphere particles or fragments. The combustion products were quenched under various cooling conditions (represented by nominal cooling rates of 6400–11,800 °C/s) for sampling. The results show that increasing cooling rate from 6400 to 11,800 °C/s substantially intensifies ash cenosphere fragmentation. Such enhanced ash cenosphere fragmentation leads to a significant shift in the particle size distribution of ash collected in the cyclone (>10 µm) to much smaller sizes. It also produces considerably more particulate matter (PM) with aerodynamic sizes less than 10 µm (i.e., PM₁₀) that consists of dominantly PM with aerodynamic sizes between 1 and 10 µm (i.e., PM_1–10) and some PM with aerodynamic sizes less than 1 µm (i.e., PM₁). It is further noted that the PM₁ is mainly PM with aerodynamic sizes between 0.1 and 1 µm (i.e., PM_0.1–1) and to a considerably lesser extent PM with aerodynamic sizes less than 0.1 µm (i.e., PM_0.1). Chemical analyses further show that both ash and PM samples contain only Fe₂O₃, indicating that complete consumption of sulphur and full oxidation of iron have been achieved during pulverised pyrite combustion under the conditions.