Charmed hadrons from coalescence plus fragmentation in relativistic nucleus-nucleus collisions at RHIC and LHC

In a coalescence plus fragmentation approach we calculate the heavy baryon/meson ratio and the \(p_T\) spectra of charmed hadrons \(D^{0}\), \(D_{s}\) and \(\varLambda _{c}^{+}\) in a wide range of transverse momentum from low \(p_T\) up to about 10 GeV and discuss their ratios from RHIC to LHC energies without any change of the coalescence parameters. We have included the contribution from decays of heavy hadron resonances and also the one due to fragmentation of heavy quarks which do not undergo the coalescence process. The coalescence process is tuned to have all charm quarks hadronizing in the \(p_T\rightarrow 0\) limit and at finite \(p_T\) charm quarks not undergoing coalescence are hadronized by independent fragmentation. The \(p_T\) dependence of the baryon/meson ratios are found to be sensitive to the masses of coalescing quarks, in particular the \(\varLambda _{c}/D^{0}\) can reach values of about \(\mathrm 1\div 1.5 \) at \(p_T \approx \, 3\) GeV, or larger, similarly to the light baryon/meson ratio like \(p/\pi \) and \(\varLambda /K\), however a marked difference is a quite weak \(p_T\) dependence with respect to the light case, such that a larger value at intermediate \(p_T\) implies a relatively large value also for the integrated yields. A comparison with other coalescence model and with the prediction of thermal model is discussed.     

Modified Kudryashov method via new exact solutions for some conformable fractional differential equations arising in mathematical biology

In this study, the modified Kudryashov method is used to construct new exact solutions for some conformable fractional differential equations. By implementing the conformable fractional derivative and compatible fractional complex transforms, the fractional generalized reaction duffing (RD) model equation, the fractional biological population model and the fractional diffusion reaction (DR) equation with quadratic and cubic nonlinearity are discussed. As an outcome, some new exact solutions are formally established. All solutions have been verified back into its corresponding equation with the aid of maple package program. We assure that the employed method is simple and robust for the estimation of the new exact solutions, and practically capable for reducing the size of computational work for solving a various class of fractional differential equations arising in applied mathematics, mathematical physics and biology.     

Effect on ion dissociation in MWCNT-based polymer nanocomposite

Polymer nanocomposite has been proven to improve the property of polymer salt complex. Organo-modified clay and inorganic oxides are the most commonly used filler for polymer nanocomposite (PNC). However, single wall carbon nanotube (SWCNT)/multiwall carbon nanotube (MWCNT) are becoming popular filler for PNC for their high surface area and high mechanical stability. In this work, a series of PNC sample has been prepared by using polyethylene oxide (PEO)-polydimethylsiloxane (PDMS) blend as polymer matrix, an optimized salt stoichiometry of Ö/Li ~15, and surface-modified MWCNT as filler. The effect of ion-polymer and ion-MWCNT interaction in the polymer nanocomposite has been investigated by using XRD, SEM, FTIR, and electrical study. X-ray diffraction pattern confirms the dispersion of MWCNT inside the polymer chain and modifies the structural parameter of the polymer matrix. FTIR spectra indicate inclusion of MWCNT inside the polymer salt complex which changes the ion dissociation/association in the polymer host matrix. Further, the changes in structural, thermal, and electrical property of the polymer salt complex system have been studied by using SEM, DSC, and impedance analysis. Dc conductivity study shows that optimized PNC sample has conductivity of 8.04 × 10⁻⁵ S cm⁻¹. This is almost two order enhancement from pure polymer salt system (10⁻⁶ S cm⁻¹).

     

xF3(x,Q2) Structure Function and Gross-Llewellyn Smith Sum Rule with Nuclear Effect and Higher Twist Correction

We present an analysis of the xF₃(x,Q²) structure function and Gross-Llewellyn Smith(GLS) sum rule taking into account the nuclear effects and higher twist correction. This analysis is based on the results presented in[N.M. Nath, et al., Indian J. Phys. 90 (2016) 117]. The corrections due to nuclear effects predicted in several earlier analysis are incorporated to our results of xF₃(x,Q²) structure function and GLS sum rule for free nucleon, corrected upto next-next-to-leading order (NNLO) perturbative order and calculate the nuclear structure function as well as sum rule for nuclei. In addition, by means of a simple model we have extracted the higher twist contributions to the non-singlet structure function xF₃(x,Q²) and GLS sum rule in NNLO perturbative orders and then incorporated them to our results. Our NNLO results along with nuclear effect and higher twist corrections are observed to be compatible with corresponding experimental data and other phenomenological analysis.     

Ion conducting phosphate glassy materials

Fast ion conducting (FIC) phosphate glasses have become very important due to a wide range of applications in solid-state devices. We present an overview on silver based fast ion conducting phosphate glasses. Silver phosphate glasses containing chlorides of some metals viz; Li, Na, Mg, Pb and Cu [Ag₂O–P₂O₅–xMCl_y, where x = 0, 1, 5, 10 and 15 wt% and y = 1 when M = Li or Na and y = 2 when M = Mg, Pb or Cu] have been synthesized by melt quenching technique. Studies on these glassy materials characterized by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetric techniques and ion transport measurements are presented. The FT-IR studies support the formation of P–O–M linkages. The values of glass transition temperature (T_g) of the glassy materials containing lithium or sodium chloride have been found to decrease with increasing dopant concentrations indicating expansion of the glassy network. On the other hand, the T_g values increase with increasing magnesium, lead or copper chloride concentrations in silver phosphate glasses. This indicates an increase in cross–link density and enhanced chemical durability of these glassy materials. Ion transport studies suggest that the values of electrical conductivities of the metal chloride doped glassy materials are higher than those of the undoped ones and, at a particular dopant concentration, the following trend is observed.σ (–LiCl) ≥ σ (–NaCl) > σ (–MgCl₂) > σ (–PbCl₂) > σ (–CuCl₂)These results are supported by the experimental results of FT-IR spectral and thermal studies.     

QM/MM study of the interaction between zigzag SnC nanotube and small toxic gas molecules

Adsorptions of small toxic molecules such as CO, N₂, HCN, SO₂, H₂CO, and NH₃ on a single‐walled (6,0) SnC nanotube (SnCNT) are investigated using Quantum Mechanics/Molecular Mechanics (QM/MM) methodology. The calculations are carried out at the B3LYP/6‐311++G(d,p)//LANL2DZ:UFF level of theory. The high layer of the model consists of a pyrene‐type ring on the nanotube surface as the adsorption site, where one gas molecule is allowed to interact. Conversely, for the adsorption of the two molecules, a larger site like a coronene ring is used for the high layer. Adsorption energy, Gibbs free energy change, Mulliken charge transfer, and total electron‐density maps are computed in each case. The adsorption strength of the gas molecule on the SnCNT surface is also analyzed from the density of states projected to different atoms (PDOS) of the nanotube–adsorbate complexes. The adsorptions of CO and N₂ on the (6,0) SnCNT surface require to cross potential barriers, and the corresponding transition structures are identified by ONIOM‐IRC calculations. For the remaining four molecules, the processes of adsorption are predicted to be barrier‐less. The calculations for the adsorption of H₂CO on (5,0) and (7,0) SnCNT surfaces are extended to study the effect of the size of the nanotube. Results for the adsorption of a single molecule on (6,0) SnCNT using B3LYP functional are compared with those obtained from a dispersion corrected functional such as M06‐2X. © 2015 Wiley Periodicals, Inc.     

Probing solute-solvent interaction in 1-ethyl-3-methylimidazolium-based room temperature ionic liquids: A time-resolved fluorescence anisotropy study

Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA?>?ESU?>?TCB?>?TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs.

Structurally Simple Ferrocene Derivatives for Selective Cadmium Sensing

Three new ferrocene based Schiff bases 4-{[(E)-ferrocenylmethylidene] amino}benzenethiol (1b), 3-{[(E)-ferrocenylmethylidene]amino} benzenethiol (1c), 2-{[(E)-ferrocenylmethylidene]amino} benzenethiol (1d) have been synthesized to study their sensor property to various metal ions. It has been observed that 1b is highly fluorescent and its fluorescence changes in presence of metal ions. It was further observed that compound 1b is highly selective towards Cd²⁺ ion in solution.     

Dielectric relaxation of CdSe nanoparticles

Nanoparticles of cadmium selenide (CdSe) have been synthesized by soft chemical route using mercaptoethanol as a capping agent. X-ray diffraction and transmission electron microscope measurements show that the prepared sample belongs to sphalerite structure with the average particle size of 25 nm. The band gap of the material is found to be 2.1 eV. The photoluminescence (PL) emission spectra of the sample are measured at various excitation wavelengths. The PL spectra appear in the visible region, and the emission feature depends on the wavelength of the excitation. Impedance spectroscopy is applied to investigate the dielectric relaxation of the sample in a temperature range from 323 to 473 K and in a frequency range from 42 Hz to 1.1 MHz. The complex impedance plane plot has been analyzed by an equivalent circuit consisting of two serially connected R-CPE units, each containing a resistance (R) and a constant phase element (CPE). The dielectric relaxation of the sample is investigated in the electric modulus formalism. The temperature dependent relaxation times obey the Arrhenius law. The Havriliak–Negami model is used to investigate the dielectric relaxation mechanism in the sample. The frequency dependent conductivity spectra are found to obey the power law.     

Laser diode to single-mode circular core dispersion-shifted/dispersion-flattened fiber excitation via hyperbolic microlens on the fiber tip: Prediction of coupling efficiency by ABCD matrix formalism

The formulated ABCD matrix formalism is employed to prescribe analytical expression of coupling efficiency of a laser diode to single-mode circular core dispersion-shifted as well as dispersion-flattened fiber via hyperbolic microlens on the tip of the fiber. We assume that field distribution in case of both the source and the fiber is one parameter Gaussian type. For maximum excitation efficiency, it is required that the lens transmitted spot size of the source should match with the spot size of the fiber. Further, as regards the spot size of the fiber, we use Petermann II spot size in order to take care of non Gaussian nature of field of such fibers and to make the estimations more realistic thereby. The investigations are carried out for two different wavelengths 1.3 and 1.5 μm. Our simple method predicts the concerned coupling optics excellently and the necessary evaluations require little computations. This simple but accurate technique is expected to benefit the system designers who work in the field of optical technology.