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The critical adsorption of semi-flexible polymer chains on attractive surfaces is studied using Monte Carlo simulations. The results reveal that the critical adsorption point of a free polymer chain is the same as that of an end-grafted one. For the end-grafted polymer, we find that the finite-size scaling relation and the maximum fluctuation of adsorbed monomers are equivalent in estimating the critical adsorption point. The effect of chain stiffness on the critical adsorption is also investigated. The surface attraction strength for the critical adsorption of semi-flexible polymer chain decreases exponentially with an increase in the chain stiffness; In other words, lower adsorption energy is needed to adsorb a stiffer polymer chain. The result is explained from the viewpoint of the free energy profile for the adsorption.

Mg-doped GaN nanowires have been synthesized by ammoniating Ga2O3 films doped with Mg under flowing ammonia atmosphere at 850° C. The Mg-doped GaN nanowires are characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM) and photo-luminescence (PL). The results demonstrate that the nanowires are single crystalline with hexagonal wurzite structure. The diameters of the nanowires are 20–30 nm and the lengths are 50–100 μm. The GaN nanowires show three emission bands with well-defined PL peak at 3.45 eV, 3.26 eV, 2.95 eV, respectively. The large distinct blueshift of the bandgap emission can be attributed to the Burstein–Moss effect. The peak at 3.26 eV represents the transition from the conduction-band edge to the acceptor level AM (acceptor Mg). The growth mechanism of crystalline GaN nanowires is discussed briefly.

Bi2Te3 thin films and GeTe/B2Te3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric (TE) measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi2Te3 thin films and GeTe/B2Te3 superlattices, respectively. High TE performances with figure-of-merit (ZT) values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi2Te3 thin films, respectively. These ZT values are higher than those of p-type Bi2Te3 alloys as reported. Relatively high ZT of the GeTe/B2Te3 superlattices at 300–380 K were 0.62–0.76. The achieved high ZT value may be attributed to the unique nano- and micro-structures of the films, which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi2Te3-based thin films can serve as high-performance materials for applications in TE devices.

We present the first phase RD the three-stage development from the beam test tube to the klystron having a high efficiency structure. Design of the beam test tube that comprises electron gun and collector is presented. First, gun simulation having a modulating anode is performed using DGUN software. The uniform beam trajectories with a beam perveance of 0.64 μA/V are simulated. We employ a Ba-dispenser cathode of radius 35 mm with 10 hole at the center and obtain a current density on cathode less than 0.45 A/cm2. The beam trajectories are also simulated over beam test tube of length about 2 m with a magnetic field of 213 Gauss. Thermal analysis of the collector is performed using the ANSIS-CFX code and hence the cooling structure is determined. Mechanical design is almost carried out and it is in manufacturing stage.

We investigate the influence of precursor molar ratio of [S2−]/[Zn2+] on particle size and photoluminescence (PL) of ZnS:Mn2+ nanocrystals. By changing the [S2−]/[Zn2+] ratio from 0.6 (Zn-rich) to 2.0 (S-rich), the particle size increases from nearly 2.7 nm to about 4.0 nm. The increase in the ratio of [S2−]/[Zn2+] causes a decrease of PL emission intensity of ZnS host while a distinct increase of Mn2+ emission. The maximum intensity for the luminescence of Mn2+ emission is observed at the ratio of [S2−]/[Zn2+]≈1.5. The possible mechanism for the results is discussed by filling of S2− vacancies and the increase of Mn2+ ions incorporated into ZnS lattices.

A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.

We present a polarization-insensitive broadband absorber which has a feature of metal-insulator-metal structures. The top metal layer consists of four-fan-rings-shaped gold. Simulations show that the absorber exhibits an absorption of nearly unity at the wavelength of 386.1 nm and a relative absorption bandwidth of 0.548, which refers to the ratio of the full absorption bandwidth over an absorption of 0.9 to the central wavelength. Meanwhile, the absorption is nearly independent of the polarized direction of the incident wave. This absorption bandwidth with insensitive polarization is widely reported to date for such metal-insulator-metal structures. Such a structure offers a way of realization of a polarization-insensitive broadband absorber ranging in ultraviolet-to-visible wavelengths.

We propose a new method to control the directed quantum transport of ultracold atoms in a one-dimensional optical lattice. In this proposal, the effective tunneling between the neighboring sites can be adjusted via coherent destruction of tunneling by tuning the phase of the external field, instead of using the driving field intensity or the frequency, thus the directed quantum transport of ultracold atoms can be coherently controlled in a much easier manner. Our proposal overcomes the major drawback of the method used by Creffield et al. [Phys. Rev. Lett. 99 (2007) 110501], and can be implemented, in principle, in any one-dimensional optical lattice. Some potential applications of the scheme are also discussed.

A novel visible light driven photocatalytic reactor with 547 pieces of Ag/AgBr-film-modified capillaries is reported and it is derived from a microstructured polymer optical fiber (MPOF) preform. The MPOF preform not only plays the role of a light-transmitting media, but it is also a Ag/AgBr supporting and waste-water pipe to supply the photocatalytic degradation of dyes solute. The photocatalytic reactor has such a large surface area for Ag/AgBr loading, which is a visible light driven photocatalyst that photodegradation efficiency is enhanced.

The lateral resolution (LR) and signal-to-noise ratio (SNR) are the essential factors in the applications of scanning probe microscopy in quantitative measurement of surface charge distribution, potential profile, and dielectric properties. We use a model system to comprise Au nanoparticles (NPs) embedded in a polystyrene (PS) matrix to study the effects of various experimental parameters, such as modulation bias voltage, tip-sample distance, and actual tip shape, on the electrostatic interactions between the tips and samples. The results show that LR and SNR decrease when the tip-sample distance increases, while SNR increases with tip modulation voltage. LR is less sensitive to tip modulation voltage, but shows complex dependence on the sample geometric structure. In combination with a numerical simulation based on the integral capacitance model, the electrostatic force interaction between tip and sample was quantitatively analyzed.

Vibrational spectra (Raman 4000-95 cm−1 and mid-IR 4000-400 cm−1) of the atacamite-structure Ni2(OH)3Cl, including a rarely reported kind of asymmetric trimetric hydrogen bond, as a member of the geometrically frustrated material series and its deuteride Ni2(OD)3Cl are, to the best of our knowledge, reported for the first time and analyzed at room temperature. Through a comparative study of four spectra according to their crystal structural parameters, we assign OH stretching modes v(OH) in a functional group region (3700-3400 cm−1) and their deformation modes δ(NiOH/D) in the correlation peak region (900-600 cm−1) with the corresponding mode frequency ratios ωv(OD)/ωv(OH)≈73% and ωδ(NiOD)/ωδ(NiOH)≈75%, and further self-consistently suggest NiO and Ni-Cl related modes in the fingerprint region (500-200 cm−1 and 200-0 cm−1, respectively) by use of the unified six-ligand NiO5Cl and NiO4Cl2 frames. This report may contribute to the spectral analysis of other hydroxyl transition-metal halides and to the understanding of the fundamental physics of their exotic magnetic geometrical frustration property from the spectral changes around the corresponding low transition temperatures.

Electron energy loss spectra of inner-shell excitations of 2p electrons of argon are measured at an incident electron energy of 2500 eV and scattering angles of 0° and 4°. The dipole-forbidden transitions of 2p−13/24p and 2p−13/25p are observed in the measured spectra and assigned based on the calculations of the Cowan code. The positions and line widths for the excitations of 2p−13/2nl and 2p−11/2nl (n ≤ 5) of argon are determined. The present results show that the line widths of the electric quadrupole transitions of 2p−13/24p[5/2 + 3/2]2 and the electric monopole one of 2p−13/24p[1/2]0 are less than those of the dipole-allowed transitions.

A mobile molecular Doppler wind lidar (DWL) based on double-edge technique is presented for wind measurement at altitudes from 10km to 40km. A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity. The lidar operates at 355 nm with a 45-cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing. In order to guarantee the wind accuracy, different forms of calibration function of detectors in different count rates response range would be especially valuable. The accuracy of wind velocity iteration is improved greatly because of application of the calibration function of linearity at the ultra low light intensity especially at altitudes from 10km to 40km. The calibration functions of nonlinearity make the transmission of edge channel 1 and edge channel 2 increase 38.9% and 27.7% at about 1 M count rates, respectively. The dynamic range of wind field measurement may also be extended because of consideration of the response function of detectors in their all possible operating range.

Half-lives of proton radioactivity are investigated with a deformed density-dependent model. The single folding potential which is dependent on deformation and orientation is employed to calculate the proton decay width through the deformed potential barrier. In addition, the spectroscopic factor is taken into account in the calculation, which is obtained in the relativistic mean field theory with NL3. The calculated results of semi-spherical nuclei are found to be in good agreement with the experimental data, and the results of well-deformed nuclei are also satisfactory. Moreover, a formula for the spherical proton emission half-life based on the Gamow quantum tunneling theory is presented.

Half-lives of the proton radioactivity for spherical proton emitters are investigated theoretically in the Wentzel-Kramers-Brillouin approximation. Microscopic proton-nucleus interaction potentials are obtained by folding the densities of the residual daughter nuclei with renormalized M3Y effective interactions. We also take the spectroscopic factor (Sp) into account in the calculation, which is evaluated in the relativistic mean field approach using the force NL3. The calculated results are found to be in good agreement with the experimental data.

Spherical organic-bonded ZnS nanocrystals with 4.0?0.2 nm in diameter are synthesized by a liquid-solid-solution method. The photoluminescence spectrum of sample ([S2?]/[Zn2+] = 1.0) shows a strong white emission with a peak at 490 nm and ~ 170 nm full widths at half maximum. By Gauss fitting, the white emission is attributed to the overlap of a blue emission and a green-yellow emission, originating from electronic transitions from internal S2? vacancies level to valence band and to the internal Zn2+ vacancy level, respectively. After sealingZnS nanocrystals onto InGaN chips, the device shows CIE coordinates of (0.29,0.30), which indicates their potential applications for white light emitting diodes.

By using a pump-probe technique, the nascent rotational and vibrational state distributions of CsH are obtained in the Cs(62D,72D) plus H2 reaction. The nascent CsH molecules are found to populate the lowest two vibrational (ν'' = 0 and 1) levels of the ground electronic state. By comparing the spectral intensities of the CsH action spectra with those of pertinent Cs atomic fluorescence excitation spectra, the relative reactivity with H2 is in an order of 62D3/2 > 62D5/2 > 72D3/2 > 72D5/2. The rotational temperatures are found to be slightly below the cell temperature. The relative fractions (fV, fR, fT) of average energy disposal are derived as (0.2,0.12,0.68), (0.2,0.12,0.68), (0.07,0.04,0.89) and (0.07,0.04,0.89) for the 62D3/2, 62D5/2, 72D3/2 and 72D5/2, respectively. The major available energy is released as translation. These results support that the reaction mechanism of Cs(62D,72D) plus H2 is primarily a collinear abstraction and not an insertion.