The Effect of Dark Matter on Solar System and Perihelion Precession of Earth Planet

This paper visualizes effect of dark matter on solar system and especially perihelion precession of Earth planet. The relation between the rate of perihelion shift of Earth planet and dark matter are obtained.     

Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Solid phase preconcentration of iron as methylthymol blue complex on naphthalene-tetraoctylammonium bromide adsorbent with subsequent flame atomic absorption determination

A sensitive and selective preconcentration method for the determination of trace amounts of iron by atomic absorption spectrometry has been developed. Iron forms a complex with methylthymol blue at pH=3. This complex is retained by naphthalene tetraoctylammonium bromide adsorbent in a column with a height of about 2 cm. The adsorbed metal complex is then eluted from the column with nitric acid and its iron content is determined by flame atomic absorption spectrometry (FAAS). The effect of different variables such as pH, reagent concentration, flow rate and interfering ions on the recovery of the analyte was investigated. The calibration graph was linear in the range 25-350 ng ml⁻¹ of iron in the initial solution with r=0.9994. The limit of detection based on 3S_b criterion was 12 ng ml⁻¹ and the relative standard deviation for eight replicate measurements of 150 and 300 ng ml⁻¹ of iron was 3.1 and 1.8%, respectively. This procedure was successfully applied to the determination of iron in tap and sewage water samples.     

Effects of synthesis methods of vanadium oxide nanotubes on the inter layer distances

Vanadium oxide nanotubes were synthesized via two methods: (1) Adding a template to vanadium oxide gels, (2) Grinding mixture of a template and vanadium oxide by using a ball mill. Influence of preparation method on structure of vanadium oxide nanotubes has been investigated. Vanadium oxide nanotubes has been characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) techniques.     

The effects of rate of expansion and injection of water droplets on the entropy generation of nucleating steam flow in a Laval nozzle

The entropy generation due to irreversible heat transfer between vapor and liquid phases in a nucleating steam flow in a Laval nozzle is studied. To calculate the entropy generation due to self-condensation in transonic steam flow, a thermodynamic model is presented. The calculations of nucleating steam flow and the predictions of entropy generation rely on one-dimensional two-phase model. This model shows that the most of the thermodynamic losses take place during the nucleation phenomena. The effect of rate of expansion on the exergy losses is considered by decreasing the divergent angle of nozzle. Also micro-sized pure water droplets is injected theoretically to supercooled steam right after the nozzle throat at the onset of divergent section and the effects of injected droplets on thermodynamic losses and nucleation phenomena are investigated. The results indicate that decreasing the divergent angle and also injection of droplets diminishes the pressure rise in transonic steam flow and decreases the thermal entropy generation due to nucleation.     

Quantum dynamics in a time-dependent cylindrical trap

Solutions to the Schrödinger equation are examined for a particle inside a cylindrical trap of a circular time-dependent cross-section. Analytical expressions for energy and momentum expectation values are derived with respect to the exact solutions; and the adiabatic and sudden change of the boundary are discussed. The density profile as a function of time in a given observation point, resembles the diffraction-in-time pattern observed in a suddenly released particle but with an enhanced fringe visibility. Numerical computations are presented for both contracting and expanding boxes.     

NBO,NMR Analysis,and Hybrid DFT Study of Structural and Configurational Properties of Di-tert-butyl-, bis(trimethysilyl)-, Bis(trimethgermyl)-, and Bis(trimethylstannyl)- cyclopenta-1,3-dienes

Abstract

The alkyl 1,2-shift in di-tert-butylcyclopenta-1,3-diene (1) and the metallotropic 1,2-shifts in bis(trimethylsilyl)cyclopenta-1,3-diene (2), bis(trimethylgermyl)cyclopenta-1,3-diene (3), and bis(trimethylstannyl)cyclopenta-1,3-diene (4) have been investigated by means of natural bond orbital (NBO), nuclear magnetic resonance (NMR) analysis, and hybrid density functional theory based methods. The B3LYP/DZVP results showed that the M(CH₃)₃ group [M = C (1), Si (2), Ge (3), and Sn (4)] migration barrier heights around cyclopentadienyl rings decrease from di-tert-butylcyclopenta-1,3-diene to its stannane derivative. Also, based on the results obtained, the stabilities of the 5,5-isomers in comparison to the 1,5- and 2,5-isomers increase from di-tert-butylcyclopenta-1,3-diene to its stannane derivative. The results suggest that in these compounds the metallotropic shifts are controlled by the stabilization energies associated with σ→π* electron delocalizations and the increase of the σ_C5-M→π*_C1-C2 electron delocalizations facilitates the M(CH₃)₃ group migrations around cyclopentadienyl rings. Based on the aromatic stabilization energy (ASE) values calculated, the aromaticity increases from the 5,5-isomers of di-tert-butylcyclopenta-1,3-diene to its stannane derivative but the variation of the nucleus-independent chemical shift, NICS(0) and NICS(1), values calculated are not in accordance with the ASE values calculated and the σ_C5-M→π*_C1-C2

electron delocalizations. The correlations between the sigmatropic shift barrier heights, σ→π* electron delocalizations, ASE, and NICS values were investigated.

GRAPHICAL ABSTRACT     

Investigation of the Kerr effect and third-order susceptibility constants in a nematic liquid crystal

In this paper, the static Kerr effect was investigated for the W-1680 at temperatures above the nematic-isotropic transition temperature and compared with 9CHBT. We experimentally measured the electro-optical Kerr constant and the pre-transitional behavior. The Kerr law has been confirmed and the variation of the inverse Kerr constant, with a temperature above the smectic-isotropic transition temperatures, were determined. The linear dependence of (T − T*)^− 1 on the Kerr constant is found to be in good agreement with the predications of the Landau-De Gennes model. Additionally, the temperature dependence of third order susceptibility has been studied. This value for these samples will reduce when the temperature increases.     

Rheological and transport properties of sulfonated polyacrylamide hydrogels for water shutoff in porous media

In this research, an optimal hydrogel, based on sulfonated polyacrylamide, was synthesized by statistical design of experiments using central composite method. This new hydrogel composed of sulfonated polyacrylamide (AN125VLM) and chromium triacetate as copolymer and crosslinker, respectively. The bottle and rheological tests were conducted to investigate the gelation time, thermal stability, gel strength and also ultimate elastic modulus, complex modulus, and yield stress. It was found that copolymer concentration had the main effect in both rheological and transport properties of hydrogels. The sample prepared at optimum condition, i.e. copolymer concentration of 26,340 ppm and crosslinker/copolymer ratio of 0.12, had an ultimate elastic modulus of 29.9 kPa, yield stress of 800 Pa, and complex modulus of 32 kPa. A coreflooding test through fracture was carried out to examine the optimum gel performance in a porous media. A value of 483 for the residual resistance factor ratio of water to oil confirmed the high ability of the hydrogel in reducing the relative permeability of water to oil in fractured media. Copyright © 2014 John Wiley & Sons, Ltd.     

Silica-based ionic liquid coating for 96-blade system for extraction of aminoacids from complex matrixes

1-Vinyl-3-octadecylimidazolium bromide ionic liquid [C₁₈VIm]Br was prepared and used for the modification of mercaptopropyl-functionalized silica (Si-MPS) through surface radical chain-transfer addition. The synthesized octadecylimidazolium-modified silica (SiImC₁₈) was characterized by thermogravimetric analysis (TGA), infrared spectroscopy (IR), ¹³C NMR and ²⁹Si NMR spectroscopy and used as an extraction phase for the automated 96-blade solid phase microextraction (SPME) system with thin-film geometry using polyacrylonitrile (PAN) glue. The new proposed extraction phase was applied for extraction of aminoacids from grape pulp, and LC–MS–MS method was developed for separation of model compounds. Extraction efficiency, reusability, linearity, limit of detection, limit of quantitation and matrix effect were evaluated. The whole process of sample preparation for the proposed method requires 270 min for 96 samples simultaneously (60 min preconditioning, 90 min extraction, 60 min desorption and 60 min for carryover step) using 96-blade SPME system.