Evolution of the spectral index after inflation

In this article we investigate the time evolution of the adiabatic(curvature) and isocurvature (entropy) spectral indices after end of inflation for all cosmological scales and two different initial conditions. For this purpose,we first extract an explicit equation for the time evolution of the comoving curvature perturbation (which may be known as the generalized Mukhanov-Sasaki equation). It shall be manifested that the evolution of adibatic spectral index severely depends on the intial conditions and just for the super-Hubble scales and adiabatic initial conditions is constat as be expected.Moreover,it shall be clear that the adiabatic spectral index after recombination approach to a constant value for the isocurvature perturbations.Finally,we re-investgate the Sachs-Wolfe effect and show that the fudge factor 1/3 in the adiabatic ordinary Sachs-Wolfe formula must be replaced by 0.4.Comment: 18 pages,4figure

On the perturbation theory in spatially closed background

In this article,we investigate some features of the perturbation theory in spatially closed universe. We will show that the perturbative field equations in a spatially closed universe always have two independent adiabatic solutions provided that the wavelengths of perturbation modes are very longer than the Hubble horizon. It will be revealed that these adiabatic solutions do not depend on the curvature directly. We also propound a new interpretation for the curvature perturbation in terms of the unperturbed geometry.Comment: 25 pages,no figures,accepted for publiction in EPJ

Curvature and topology dependency of the cosmological spectra

In this article we investigate dependency of the adiabatic and entropy spectral indices of the cosmological perturbations on the geometry and topology of the background universe. Our discussion includes the post-inflationary universe i.e. radiation-dust mixture era. For this purpose, we first extract an explicit equation describing evolution of the comoving curvature perturbation in the FLRW universe with arbitrary spatial sectional curvature. We may percept when $K\neq 0$, curvature scale would be as significant as the perturbations scales to recognize the behavior of the spectral indices. We also focus on the entropy perturbation in order to extract behavior of the isocurvature spectral index in terms of the curvature index and time. Our analysis shows that spectra of curvature and entropy perturbations in sub-horizon scales could be function of topology. Moreover, an accurate analysis makes clear that time-average of isocurvature index in case $K=0$ is about zero,so that imprint of entropy perturbation in time duration may be negligible. We also consider evolution of the cosmological indices for super-curvature modes in the case $K=-1$. In the most results dependency to curvature, initial conditions and scale modes are thoroughly vivid.Comment: 9 pages,12 figure

DOES SUPPLIER’S WILLINGNESS TO CUSTOMIZE INFLUENCE THE BUYER’S RETENTION?

Since the last decade, customer retention has become the central topic in the management and marketing decisions in many companies.  A 5% increase in customer retention can lead to 25-95 % increase in profits. A retained customer is the loyal one to the companies due to the attachment and commitment. This loyal customer will, recommend other customers to purchase and repurchase the companies’ products and services. How we can enhance customer retention? This is one of the main challenges for most of professionals, which requires a lot of investigations. Therefore, the antecedents of customer retention required enough attention. This study explores literatures on antecedents of customer retention in Business-to-Business relationship. Based on the thorough literatures done, a theoretical framework is proposed and some possible recommendations are put forward for future researches. Keywords: Customer retention; Supplier’s willingness to customize; Supplier-buye

International Medical Tourists’ Behavioral Intention: An Empirical Study in Malaysia

A few studies have examined the effect of hospital service quality, hospital accreditation, destination image on patient satisfaction and patient loyalty in a tourism context. The purpose of this study is to evaluate the effect of medical patients’ behavioural intention in Malaysia. A total of 360 questionnaire were distributed and quantitative techniques were used to test the hypotheses within the structural equation modelling (SEM) using SmartPLS software. Our statistical results support the positive effect of hospital service quality, destination image and patient satisfaction on patient loyalty. Hospital accreditation didn’t have positive impact on patient loyalty. The research contribution, implication, and limitation are discussed. Keywords: hospital service quality, destination image, hospital accreditation, patient satisfaction, patients’ loyalty

Many-body effects in van der Waals-Casimir interaction between graphene layers

Van der Waals-Casimir dispersion interactions between two apposed graphene layers, a graphene layer and a substrate, and in a multilamellar graphene system are analyzed within the framework of the Lifshitz theory. This formulation hinges on a known form of the dielectric response function of an undoped or doped graphene sheet, assumed to be of a random phase approximation form. In the geometry of two apposed layers the separation dependence of the van der Waals-Casimir interaction for both types of graphene sheets is determined and compared with some well known limiting cases. In a multilamellar array the many-body effects are quantified and shown to increase the magnitude of the van der Waals-Casimir interactions.Comment: 13 pages, 13 figure

Novel magnetic nanoparticles with ionic liquid tags as a reusable catalyst in the synthesis of polyhydroquinolines

In this study, we have introduced {Fe3O4@SiO2@(CH2)3Im}C(NO2)3 as a novel and heterogeneous reusable catalyst for the four component preparation of polyhydroquinoline derivatives under mild and eco-friendly reaction conditions. The structural confirmation of the novel heterogeneous reusable promoter was fully made using FT-IR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS) elemental mapping analysis, high resolution transmission electron microscopy (HRTEM), thermogravimetry (TG), derivative thermal gravimetric (DTG), differential thermal (DTA) and vibrating sample magnetometer (VSM) analyses. The nanomagnetic heterogeneous catalyst was successfully applied for the synthesis of polyhydroquinoline derivatives via a four component condensation of a good range of aryl aldehydes, dimedone, ethyl acetoacetate or methyl acetoacetate as a β-ketoester, and ammonium acetate as a nitrogen source under solvent free conditions. Moreover, experimental evidence has demonstrated that {Fe3O4@SiO2@(CH2)3Im}C(NO2)3 could act as a recoverable nanomagnetic and reusable catalyst without any considerable drop in the yield and the reaction time for at least eight times.We thank the Bu-Ali Sina University, the Iran National Science Foundation (INSF) (Allameh Tabataba'i's Award, Grant Number BN093), the University of Alicante (VIGROB-173), and the Spanish Ministerio de Economía y Competitividad (CTQ2015-66624-P) for financial support to our research groups

Synthesis and application of a novel nanomagnetic catalyst with Cl[DABCO-NO2]C(NO2)3 tags in the preparation of pyrazolo[3,4-b]pyridines via anomeric based oxidation

A novel nanomagnetic catalyst with Cl[DABCO-NO2]C(NO2)3 tags was designed, synthesized and fully characterized by several techniques such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, elemental mapping analysis, thermogravimetric analysis, derivative thermal gravimetric, powder X-ray diffraction patterns, field scanning electron microscopy, high resolution transmission electron microscopy, physical adsorption and desorption of N2 isotherms (BET) and vibrating sample magnetometer. The synthesized nanomagnetic particles were used as an efficient and recyclable catalyst for the one-pot three component condensation reaction of 3-methyl-1-phenyl-1H-pyrazol-5-amine or 3-methyl-1H-pyrazol-5-amine, aryl aldehydes and malononitrile for the synthesis of pyrazolo[3,4-b]-pyridine derivatives under neat conditions.We thank Bu-Ali Sina University, Iran National Science Foundation (INSF) (Grant Number: 95831207), National Elites Foundation, University of Alicante (VIGROB-173, UAUSTI16-03), and the Spanish Ministerio de Economía y Competitividad (CTQ2015-66624-P) for financial support to our research groups

Design, synthesis, and application of 1H-imidazol-3-ium trinitromethanide {[HIMI]C(NO2)3} as a recyclable nanostructured ionic liquid (NIL) catalyst for the synthesis of imidazo[1,2-a]pyrimidine-3-carbonitriles

In this study, 1H-imidazol-3-ium trinitromethanide (1) {[HIMI]C(NO2)3} as a green and recyclable catalyst based on nanostructure ionic liquid (NIL) was designed, synthesized, fully characterized by various analysis techniques, and applied as catalyst for the synthesis of 4-amino-1,2-dihydrobenzo[4,5]imidazo[1,2-a]pyrimidine-3-carbonitrile derivatives via one-pot three-component condensation reaction. The reaction tolerates a wide range of electron-donating and electron-withdrawing substituents on aldehydes with malononitrile and 2-aminobenzimidazole at 50 °C under neat conditions. The described reaction is compatible with the green chemistry disciplines and their main advantages are short reaction time, high yields, simplicity of product isolation, and clean reaction profile. Additionally, the NIL catalyst (1) {[HIMI]C(NO2)3} can be readily recovered in the reaction vessel using a mixture of EtOAc/H2O (1:1) and reused for four consecutive runs without a significant loss in catalytic activity. The present study can open up a new and promising insight in the course of rational design, synthesis and applications of nanostructured task-specific ionic liquids (NTSILs) for numerous green purposes.We thank Bu-Ali Sina University, Iran National Science Foundation (INSF) (Grant number: 940124), National Elites Foundation, University of Alicante (VIGROB-173), and the Spanish Ministerio de Economía y Competitividad (CTQ2015-66624-P) for financial support to our research groups