Confined Acoustic Phonon in CdS1-xSex Nanoparticles in Borosilicate Glass

We calculate low-frequency Raman scattering from the confined acoustic phonon modes of CdS1-xSex nanoparticles embedded in borosilicate glass. The calculation of the Raman scattering by acoustic phonons in nanoparticles has been performed by using third-order perturbation theory. The deformation potential approximation is used to describe the electronphonon interaction. The Raman-Brillouin electronic density and the electron-phonon interaction are found to increases with decreasing size of nanoparticle. A good agreement between the calculated and reported low-frequency Raman spectra is found.Comment: 13 pages, 3 figures. Journal of Nanoscience and Nanotechnology (In Press

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

Measurement of the Higgs boson production rate in association with top quarks in final states with electrons, muons, and hadronically decaying tau leptons at s√=13TeV

The rate for Higgs (H) bosons production in association with either one (tH) or two (tt¯H) top quarks is measured in final states containing multiple electrons, muons, or tau leptons decaying to hadrons and a neutrino, using proton–proton collisions recorded at a center-of-mass energy of 13TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 137fb−1. The analysis is aimed at events that contain H→WW, H→ττ, or H→ZZ decays and each of the top quark(s) decays either to lepton+jets or all-jet channels. Sensitivity to signal is maximized by including ten signatures in the analysis, depending on the lepton multiplicity. The separation among tH, tt¯H, and the backgrounds is enhanced through machine-learning techniques and matrix-element methods. The measured production rates for the tt¯H and tH signals correspond to 0.92±0.19(stat)+0.17−0.13(syst) and 5.7±2.7(stat)±3.0(syst) of their respective standard model (SM) expectations. The corresponding observed (expected) significance amounts to 4.7 (5.2) standard deviations for tt¯H, and to 1.4 (0.3) for tH production. Assuming that the Higgs boson coupling to the tau lepton is equal in strength to its expectation in the SM, the coupling yt of the Higgs boson to the top quark divided by its SM expectation, κt=yt/ySMt, is constrained to be within −0.9<κt<−0.7 or 0.7<κt<1.1, at 95% confidence level. This result is the most sensitive measurement of the tt¯H production rate to date.SCOAP

Synthesis and characterization of flame retardant jute-g-poly (2-ethyl hexylacrylate)/montmorillonite composites

303-310Chemically modified jute fiber (Tossa variety) has been grafted onto 2-ethyl hexylacrylate (2-EHA) to prepare copolymer using <i style="mso-bidi-font-style: normal">in situ developed transition metal complex initiating system; CuSO4/glycine/potassium monopersulfate (KMPS). Then its composites have been prepared by incorporating montmorillonite (MMT) clay. The samples have been characterized by Fourier Transform-Infrared (FTIR) spectroscopy and surface morphology by Scanning Electron Microscopy (SEM). The thermal behavior and tensile strength of the samples have been studied. The fire retardant properties are studied using oxygen consumption cone calorimeter. The biodegradability of the composites has been tested to see if it is ecofriendly by nature and viable for better commercialization

Synthesis of polyacrylonitrile (PAN) catalyzed by Ni(II)/glycine chelate complex through emulsion polymerization initiated by monopersulphate

259-263A radical polymer of acrylonitrile (AN) was prepared using a non-conventional complex initiating system Ni(II)/Glycine/KHSO5 in the absence of an added emulsifier. The polymerization reaction was also carried out in the presence of various divalent transition metal salts, certain amino acids and their chelate complexes in atmospheric oxygen. The metal salts and amino acids with free amino and carboxyl groups have a retarding effect on the polymerization reaction, while their chelate complexes have catalytic effect. From among the data, NiCl2/glycine chelate complex was chosen for detailed kinetic study of acrylonitrile polymerization. The stirring of solution produces dispersion of the insoluble monomer in the continuous phase. The rate of polymerization (Rp) was studied for varying concentration of monomer, initiator, glycine, NiCl2 and solvents over a temperature range of 40-70°C. The polymers were characterized by molecular weight determination by GPC and viscosity methods. The overall activation energy was computed to be 5.35 kcal mol-1. From kinetic and spectrophotometric study, the mechanism of KHSO5 decomposition by Ni(II)/glycine complex and initiation of polymerization was suggested

Synthesis of a biodegradable polyacrylonitrile/sodium silicate nanocomposite fire retardant

139-144Polyacrylonitrile (PAN)/Sodium silicate (SS) nanocomposite was synthesized via non-conventional emulsifier free emulsion method using an in situ developed transition metal complex Cu(II)/EDTA taking potassium monopersulfate (KMPS) as initiator, with a novel motive of converting hydrophobic homopolymer PAN into hydrophilic nanocomposite by the inclusion of SS to the homopolymer. The formation of the PAN/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nano scale structure. X-ray diffraction (XRD) was carried out suggesting that the silicate layers were exfoliated or intercalated during the polymerization process. An increase in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA). The combustion behaviour has been evaluated using oxygen consumption cone calorimeter and the nanocomposite exhibited good fire retardancy. The PAN/SS nanocomposite was found to be biodegradable as tested by sludge water and further confirmed by scanning electron microscopy (SEM)

Synthesis of PAN nanoparticles via nonconventional microemulsion technique using Co(II)/EDTA in situ complex

119-125Synthesis of polyacrylonitrile nanoparticles was carried out under the catalytic effect of in situ developed Co(II)/EDTA complex with ammonium persulphate as initiator, in the absence of added emulsifier. The microemulsion polymerization was studied at varying concentrations of initiator, monomer, complex and solvent over a temperature range of 30-70ºC. The overall activation energy (Ea, 49.79 kJ/mol), energy of dissociation of initiator (Ed, 82.68 kJ/mol), number of micelles (0.163 x 1018) and the viscosity average molecular weight of the polymer were computed. The distribution of particle sizes was determined by transmission electron microscopy (TEM). It was found that the oil-in-water polymerization was stabilized by the presence of the CoCl₂/EDTA in situ complex reducing the particle size into nano order. The average diameters of PAN nano particles, obtained by TEM, were in the range of 50-150 nm at maximum conversion. The experimental particle size was mainly dependent on the concentration of complex and temperature

Synthesis and kinetics of ‘crumpled’ PMMA latex by non-conventionally initiated emulsion polymerization

341-346The aqueous emulsifier-free emulsion polymerization of methyl methacrylate (MMA) was studied under the catalytic effect of a prepared complex, [Cu(NH3)4]SO4, with various initiators like potassium peroxodisulphate (KPS), potassium monopersulphate (KMPS) and ammonium persulphate (APS). The apparent activation energies Ea were found to be 36.52 (KMPS), 40.47 (KPS) and 31.9 kJ/mol (APS). The activation energies of initiator decomposition Ed were found to be, 31.04, 38.93 and 21.79 kJ/mol for KMPS, KPS and APS, respectively. The emulsion polymer (PMMA) latex was characterized through the determination of the size and morphology by scanning electron microscopy (SEM), FTIR spectroscopy, the average molecular weight by GPC and viscosity methods. The surface of the polymer latex was found to be somewhat ‘crumpled’. From the kinetic results, the rates of polymerization, Rp, at 50°C were determined