Fluorescence dynamics of bovine serum albumin (BSA) conjugated CdZnS nanocrystallites

We report on the production of composite semiconductor CdZnS nanoparticles by adopting an inverse micellar route, using bis (2-ethylhexyl) sulfosuccinate (aerosol-AOT) as surfactant and with a degree of hydration w0=[ H2O]:[AOT]=8.9. Prior to bioconjugation (conjugation with bovine serum albumin (BSA)), the hydrophobic surface of the nanocrystals were made hydrophilic with thiol treatment (reacting with mercapto acetic acid). We compare photophysical nature of as prepared, thio-stabilized and bioconjugated CdZnS nanoparticles using absorption/emission spectroscopy and ultrafast photoluminescence decay measurements. The change-over from nonzero anisotropy (untreated) to zero anisotropy (bioconjugated) is assigned to the depolarized emission due to the surface reconstruction owing to BSA adsorption into the surface vacancies. Exploration of the dynamics of photophysical features would be promising for biomolecular sensing, labeling, and imaging applications

Morpho-physiological and Molecular Variability in Salt Tolerant and Susceptible Popular Cultivars and their Derivatives at Seedling Stage and Potential Parental Combinations in Breeding for Salt Tolerance in Rice

Saltol, a major QTL for salt exclusion, was derived from ‘Pokkali’, a salt-tolerant rice cultivar. Apart from Pokkali, many genotypes with wide variation for salinity tolerance offer ample scope for identifying new genes or QTLs underlying various tolerance mechanisms. Such genes could be aggregated into high-yielding backgrounds to reinforce a breeding programme. To identify potential donors for salt tolerance and prospective parental combinations for developing high-yielding salt-tolerant cultivars, ten genotypes were subjected to salt stress and evaluated for morpho-physiological traits and marker-allele polymorphism in the Saltol-QTL region. Although the salt-susceptible high-yielding varieties clustered together in a 3-D plot, principal component analysis showed marked spatial isolation among the tolerant genotypes. Unlike Pokkali and its derivative FL496, Rahspunjar maintained a higher level of K+ despite high Na+ influx in shoots. The wider genetic distances observed at both phenotypic and genotypic levels suggest the possibility of getting transgressive segregants among the offspring of crosses between Rahspunjar and Gayatri or Swarna Sub1. Similarly, SR 26B, which coped with the stress by diluting the Na+ load by maintaining a higher growth rate, differed from Pokkali or Nona Bokra: these two coped with the stress by regulating the transmission of Na+ from roots to photosynthetically active sites. The F2:3 population derived from Savitri × SR 26B showed wide morpho-physiological diversity for salt tolerance. SR 26B was the most distant genotype from Pokkali in the Saltol QTL region and was salt tolerant despite the absence of Pokkali alleles in this region

Characteristics of Iron Ore Slime from Kiriburu, India

The mineralogical, size and chemical characteristics of slime vary from discharge point to the distal part of the Tailing pond of Kiriburu iron ore mines. They can be grouped as three end members of slime composition- (i) coarse grained dense martite microplaty hematite type, (ii) coarse to medium grained goethite and clay dominated martite hematite type, (iii) fine grained hematite-goethite-clay type, occurring systematically away from the discharge point. Any slime will have a bulk composition intermediate to these three end members. The study has significance in the planning for exploitation of slime

Possibility of extracting the weak phase γ\gamma from Λb→ΛD0\Lambda_b \to \Lambda D^0 decays

We explore the possibility of extracting the weak phase $\gamma$ from pure tree decays $\Lambda_b \to \Lambda (D^0, \bar{D^0}, D^0_{CP})$ in a model independent way. The CP violating weak phase $\gamma$ can be determined cleanly, without any hadronic uncertainties, as these decay modes are free from the penguin pollutions. Furthermore, neither tagging nor time dependent studies are required to extract the angle $\gamma$ with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in Phys. Rev.

Effect of FCNC mediated Z boson on lepton flavor violating decays

We study the three body lepton flavor violating (LFV) decays $\mu^- \to e^- e^+ e^-$, $\tau^- \to l_i^- l_j^+ l_j^-$ and the semileptonic decay $\tau \to \mu \phi$ in the flavor changing neutral current (FCNC) mediated $Z$ boson model. We also calculate the branching ratios for LFV leptonic B decays, $B_{d,s} \to \mu e$, $B_{d,s} \to \tau e$, $B_{d,s} \to \tau \mu$ and the conversion of muon to electron in Ti nucleus. The new physics parameter space is constrained by using the experimental limits on $\mu^- \to e^- e^+ e^-$ and $\tau^- \to \mu^- \mu^+ \mu^-$. We find that the branching ratios for $\tau \to eee$ and $\tau \to \mu \phi$ processes could be as large as $\sim {\cal O}(10^{-8})$ and ${\rm Br}B_{d,s} \to \tau \mu, \tau e) \sim {\cal O}(10^{-10})$. For other LFV B decays the branching ratios are found to be too small to be observed in the near future.Comment: 15 pages, 8 figures, typos corrected, one more section added, version to appear in EPJ

Determination of the angle γ\gamma from nonleptonic Bc→DsD0B_c \to D_s D^0 decays

We note that the two body nonleptonic pure tree decays $B_c^\pm \to D_s^\pm D^0(\bar D^0)$ and the corresponding vector-vector modes $B_c^\pm \to D_s^{* \pm} D^{*0}(\bar D^{* 0})$ are well suited to extract the weak phase $\gamma$ of the unitarity triangle. The CP violating phase $\gamma$ can be determined cleanly as these decay modes are free from the penguin pollutions.Comment: 12 pages, LaTeX, 2 references added, Minor changes in the text, to appear in Phys. Rev.

Search for Higgs bosons of the Universal Extra Dimensions at the Large Hadron Collider

The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed.Comment: 25 pages, 9 figures and 1 tabl

Constraints on Astro-unparticle Physics from SN 1987A

SN 1987A observations have been used to place constraints on the interactions between standard model particles and unparticles. In this study we calculate the energy loss from the supernovae core through scalar, pseudo scalar, vector, pseudo vector unparticle emission from nuclear bremsstrahlung for degenerate nuclear matter interacting through one pion exchange. In order to examine the constraints on $d_{\cal U}=1$ we considered the emission of scalar, pseudo scalar, vector, pseudo vector and tensor through the pair annihilation process $e^+e^-\to {\cal U} \gamma$. In addition we have re-examined other pair annihilation processes. The most stringent bounds on the dimensionless coupling constants for $d_{\cal U} =1$ and $\Lambda_{\cal U}= m_Z$ are obtained from nuclear bremsstrahlung process for the pseudo scalar and pseudo-vector couplings $\bigl|\lambda^{\cal P}_{0,1}\bigr|\leq 4\times 10^{-11}$ and for tensor interaction, the best limit on dimensionless coupling is obtained from $e^+ e^-\to {\cal U} \gamma$ and we get $\bigl|\lambda^{\cal T}\bigr| \leq 6\times 10^{-6}$.Comment: 12 pages, 2 postscript figure

Bounds on Heavy-to-Heavy Mesonic Form Factors

We provide upper and lower bounds on the form factors for B -> D, D^* by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to leading order in Lambda_QCD/m_Q and alpha_s. The O(alpha_s^2 beta_0) corrections to the bounds at zero recoil are also presented. We compare our bounds with some of the form factor models used in the literature. All the models we investigated failed to fall within the bounds for the combination of form factors (omega^2 - 1)/(4 omega)|omega h_{A2}+h_{A3}|^2.Comment: 27 pages, 10 figure