Third order harmonics generation in multilayer nanoshells

Third order harmonics generation has been investigated for multilayer nanoshell structure. Numerical calculations show that the nonlinear susceptibility of this structure depends on the parameters such as size and kind of structure, relaxation time and pump photon energy. The intensity and position of third order nonlinear susceptibility peaks depend on shell thicknesses; smaller thicknesses have peak susceptibility at shorter wavelength.     

Catalytic oxidation of benzene at low temperature over novel combination of metal oxide based catalysts: CuO,MnO2, NiO with Ce0.75Zr0.25O2 as support

Mesoporous Ce_0.75Zr_0.25O₂ solid solution powders were successfully synthesized by a co-precipitation method. A combination of 10 wt% copper oxide, manganese oxide, and nickel oxide was added to the Ce_0.75Zr_0.25O₂ support by impregnation method and calcined in the air with a flow rate of 2 ml s^?1 at 400 °C for 4 h. All catalysts were characterized using Hydrogen Temperature Programmed Reduction (H₂-TPR), X-ray Diffraction (XRD), and Brunauer-Emmet-Teller (BET) isotherm methods to find the interaction between metals, the crystallinity of the catalyst, surface area and pore volume of the catalyst, respectively. The 3.3% CuO-3.3% MnO₂-3.3% NiO/Ce_0.75Zr_0.25O₂ catalyst showed higher catalytic activity for benzene oxidation with benzene conversion of 90% at 250 °C and weight hourly space velocity (72,000 mL g^?1 h^?1) when compared to one metal oxide only. This finding presents a high activity and low-cost catalysts for removing a very lean concentration of benzene containing in the industrial flue gas at low temperatures.     

Experimental evaluation of the pressure and temperature dependence of ion-induced nucleation

An experimental system for the study of ion-induced nucleation in a SO(2)/H(2)O/N(2) gas mixture was developed, employing a soft x-ray at different pressure and temperature levels. The difficulties associated with these experiments included the changes in physical properties of the gas mixture when temperature and pressure were varied. Changes in the relative humidity (RH) as a function of pressure and temperature also had a significant effect on the different behaviors of the mobility distributions of particles. In order to accomplish reliable measurement and minimize uncertainties, an integrated on-line control system was utilized. As the pressure decreased in a range of 500-980 hPa, the peak concentration of both ions and nanometer-sized particles decreased, which suggests that higher pressure tended to enhance the growth of particles nucleated by ion-induced nucleation. Moreover, the modal diameters of the measured particle size distributions showed a systematic shift to larger sizes with increasing pressure. However, in the temperature range of 5-20 °C, temperature increases had no significant effects on the mobility distribution of particles. The effects of residence time, RH (7%-70%), and SO(2) concentration (0.08-6.7 ppm) on ion-induced nucleation were also systematically investigated. The results show that the nucleation and growth were significantly dependent on the residence time, RH, and SO(2) concentration, which is in agreement with both a previous model and previous observations. This research will be inevitable for a better understanding of the role of ions in an atmospheric nucleation mechanism.     

Decoy states and two way quantum key distribution schemes

We study the possible application of the decoy state method on a basic two way quantum key distribution (QKD) scheme to extend its distance. Noting the obvious advantage of such a QKD scheme in allowing for single as well as double photon contributions, we derive relevant lower bounds on the corresponding gains in a practical decoy state implementation using two intensities for decoy states. We work with two different approaches in this vein and compare these with an ideal infinite decoy state case as well as the simulation of the original.     

Influential DMUs and outlier detection in data envelopment analysis with an application to health care

This paper explains some drawbacks on previous approaches for detecting influential observations in deterministic nonparametric data envelopment analysis models as developed by Yang et al. (Annals of Operations Research 173:89–103, 2010). For example efficiency scores and relative entropies obtained in this model are unimportant to outlier detection and the empirical distribution of all estimated relative entropies is not a Monte-Carlo approximation. In this paper we developed a new method to detect whether a specific DMU is truly influential and a statistical test has been applied to determine the significance level. An application for measuring efficiency of hospitals is used to show the superiority of this method that leads to significant advancements in outlier detection.     

Valence band studies of the formation of ultrathin pure silicon nitride films on Si(1 0 0)

The growth of ultrathin films of Si₃N₄ directly on Si surfaces is studied with valence band photoemission. The information from these studies about the growth mechanism and the changes of the electronic structure is enhanced by the use of various photon energies with synchrotron radiation. The silicon nitride films are grown isothermally on the Si(1 0 0) and Si(1 1 1) surfaces by reactions with atomic N. The atomic nitrogen is produced by using a remote, microwave excited nitrogen plasma. The growth under these conditions was earlier shown to be self limiting. The details in the valence band spectra are identified and resolved with numerical methods, and followed systematically during the growth. Thus the identification of Si surface states, Si-nitride interface states and bulk nitride states becomes possible. The previously obtained separation between amorphous and crystalline growth occurring around 500 °C is further supported in the present studies.     

Quantum key distribution in terms of the Greenberger-Horne-Zeilinger state: Multi-key generation

In this paper, we develop, a quantum key distribution protocol based on the Greenberger-Horne-Zeilinger states (GHZs). The particles are exchanged among the users in blocks through two steps. In this protocol, for three-particle GHZs three keys can be simultaneously generated. The advantage of this is that the users can select the most suitable key for communication. The protocol can be generalized to N users to provide N keys. The protocol has two levels for checking the eavesdroppers. Moreover, we discuss the security of the protocol against different attacks.     

Independent attacks in imperfect settings: A case for a two-way quantum key distribution scheme

We review the study on a two-way quantum key distribution protocol given imperfect settings through a simple analysis of a toy model and show that it can outperform a BB84 setup. We provide the sufficient condition for this as a ratio of optimal intensities for the protocols.     

Theoretical study of hybrid TEA–CO2 lasers

Temporal and spatial analysis of dynamics of hybrid transversely excited atmospheric pressure (TEA)–CO₂ lasers is studied using two different models with four and eight energy levels. These models are used for simulation of the laser and computing the output energy. Effects of several parameters such as input energies and gas mixture concentrations (especially presence of CO molecules) are also studied.     

Computational insights into octyl-D-xyloside isomers towards understanding the liquid crystalline structure: physico-chemical features

We applied density functional theory to study octyl-D-xyloside isomers in order to explain the features responsible for the liquid crystal mesophases. Compared to a glucoside, the xylose headgroup has a proton instead of the hydroxymethyl group on C5. Thus, a xyloside has a reduced headgroup volume that renders it less hydrophilic. Our results have shown that the xylose headgroup may adopt stable pyranose and furanose conformations, which may lead to different effective headgroup hydrophilicities. These features are probably responsible for forming two non-equivalent inverse micelles, which are self-assembled into a cubic discontinuous phase with a space group of Fd3m commonly found for xylosides. While different factors are responsible for controlling the relative stability of each isomer, the role of intramolecular hydrogen bonding was highlighted for the investigated single molecule. The polarisable continuum model was used to take into account the solvent effect in order to understand the molecular behaviour in very polar systems. Results from calculations carried out in gas phase were used for comparative purposes. The molecular electrostatic potential calculations for these xylolipids demonstrate sugar amphoterism, which is implicated in the heterogeneity nature of lipid self-assembly.