A novel method for observation by unaided eyes of nitrogen ion tracks and angular distribution in a plasma focus device using 50 Hz–HV electrochemically-etched polycarbonate detectors

A novel ion detection method has been developed and studied in this paper for the first time to detect and observe tracks of nitrogen ions and their angular distribution by unaided eyes in the Amirkabir 4 kJ plasma focus device (PFD). The method is based on electrochemical etching (ECE) of nitrogen ion tracks in 1 mm thick large area polycarbonate (PC) detectors. The ECE method employed a specially designed and constructed large area ECE chamber by applying a 50 Hz–high voltage (HV) generator under optimized ECE conditions. The nitrogen ion tracks and angular distribution were efficiently (constructed for this study) amplified to a point observable by the unaided eyes. The beam profile and angular distribution of nitrogen ion tracks in the central axes of the beam and two- and three-dimensional iso-ion track density distributions showing micro-beam spots were determined. The distribution of ion track density along the central axes versus angular position shows double humps around a dip at the 0° angular positions. The method introduced in this paper proved to be quite efficient for ion beam profile and characteristic studies in PFDs with potential for ion detection studies and other relevant dosimetry applications.     

Gold nanoparticle shape effects on human serum albumin corona interface: a molecular dynamic study

Three-dimensional (3D) hierarchical rutile TiO₂ microspheres composed of nanorods with diameter of several-tens of nanometers, with different morphologies and with average size ranging from 1.3 to 1.8 μm, were successfully synthesized through a surfactant-free solvothermal route. The effects of the solvents n-hexane, chloroform, and cyclohexane on the microstructures of 3D hierarchical TiO₂ nanostructures were investigated. Results of scanning electron microscopy showed that 3D sea-urchin like hierarchical TiO₂ composed of nanorods with a diameter of ~10 nm can only be prepared in the cyclohexane-water system. The growth mechanism of 3D sea-urchin like hierarchical TiO₂ composed of numerous nanorods was further examined and found to differ from the well-known “growth → assembly” mode. The effects of surface tension and polarity of solvents on the morphology and crystal strength of 3D hierarchical TiO₂ nanostructure were also investigated. In addition, the prepared 3D sea-urchin like hierarchical TiO₂ showed highest photocatalytic activity compared with other 3D hierarchical TiO₂ nanostructures in this study and Degussa P25 for the degradation of Rhodamine B solution under UV light irradiation, which could be attributed to its special hierarchical superstructure, the increase of surface catalytic sites and its special composition units.     

Competition and interplay between σ-hole and π-hole interactions: a computational study of 1:1 and 1:2 complexes of nitryl halides (O2NX) with ammonia

Quantum calculations at the MP2/cc-pVTZ, MP2/aug-cc-pVTZ, and CCSD(T)/cc-pVTZ levels have been used to examine 1:1 and 1:2 complexes between O(2)NX (X = Cl, Br, and I) with NH(3). The interaction of the lone pair of the ammonia with the σ-hole and π-hole of O(2)NX molecules have been considered. The 1:1 complexes can easily be differentiated using the stretching frequency of the N-X bond. Thus, those complexes with σ-hole interaction show a blue shift of the N-X bond stretching whereas a red shift is observed in the complexes along the π-hole. The SAPT-DFT methodology has been used to gain insight on the source of the interaction energy. In the 1:2 complexes, the cooperative and diminutive energetic effects have been analyzed using the many-body interaction energies. The nature of the interactions has been characterized with the atoms in molecules (AIM) and natural bond orbital (NBO) methodologies. Stabilization energies of 1:1 and 1:2 complexes including the variation of the zero point vibrational energy (ΔZPVE) are in the ranges 7-26 and 14-46 kJ mol(-1), respectively.     

PT-Symmetric Talbot Effects

We show that complex PT-symmetric photonic lattices can lead to a new class of self-imaging Talbot effects. For this to occur, we find that the input field pattern has to respect specific periodicities dictated by the symmetries of the system. While at the spontaneous PT-symmetry breaking point the image revivals occur at Talbot lengths governed by the characteristics of the passive lattice, at the exact phase it depends on the gain and loss parameter, thus allowing one to control the imaging process.     

Automated Technique for Identifying Experimental Vibrational–Rotational Molecular Spectra Based on Variational Calculations

We describe a technique for automated identification of experimental vibrational–rotational molecular spectra, which is based on variational calculations. The proposed technique is used to analyze the experimental spectra of triatomic molecules H₂O and HDO. This technique significantly accelerates processing and analysis of experimental data and drastically improves accuracy and quality of the results obtained. The possibility of applying this technique for analyzing spectra of other polyatomic molecules is discussed.     

Water vapour line assignments in the 9250-26 000 cm frequency range

Line parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm⁻¹ region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm⁻¹ region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H₂¹⁶O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented.     

An Efficient Three‐Component Synthesis of Pyranoquinoline Derivatives

Pyranoquinoline derivatives have been synthesized via three‐component reaction of 4‐hydroxy‐1‐methyl‐2(1H)‐quinolinone and dialkyl acetylenedicarboxylates in the presence of nucleophiles such as alkyl isocyanides and triphenylphosphine.     

A self-dual variational approach to stochastic partial differential equations

Unlike many of their deterministic counterparts, stochastic partial differential equations are not amenable to the methods of calculus of variations à la Euler–Lagrange. In this paper, we show how self-dual variational calculus leads to variational solutions of various stochastic partial differential equations driven by monotone vector fields. We construct solutions as minima of suitable non-negative and self-dual energy functionals on Itô spaces of stochastic processes. We show how a stochastic version of Bolza's duality leads to solutions for equations with additive noise. We then use a Hamiltonian formulation to construct solutions for non-linear equations with non-additive noise such as the stochastic Navier–Stokes equations in dimension two.     

Utilization of a robust syringe-to-syringe displacement-assisted dispersive liquid-phase microextraction to the preconcentration and determination of palladium in environmental samples with the aid of experimental design

Journal of the Iranian Chemical Society - We introduce a syringe-to-syringe displacement-assisted dispersive liquid-phase microextraction to the separation and preconcentration of trace Pd(II)...