B-> K photon photon via intermediate eta'

We examine our previous conjecture that the eta' intermediate resonance has the dominant role in the long distance contributions to B decay into two photons and a strange final state hadron. We calculate the branching ratio of the exclusive B-> K eta'-> K photon photon decay using the nonspectator mechanism for eta' production in charmless hadronic B decays. It is shown that the obtained branching ratio B^eta'(B-> K\gamma\gamma)~ 8.7 X 10^{-7} is more than twice as large as the eta_c contribution to this decay mode.Comment: 6 pages, latex, no figure

Spectator Effects in the Decay B -> K \gamma \gamma

We report the results of the first computation related to the study of the spectator effects in the rare decay mode $B\to K \gamma \gamma$ within the framework of Standard Model. It is found that the account of these effects results in the enhancement factor for the short-distance reducible contribution to the branching ratio.Comment: 5 pages, 5 figures, RevTeX

CP violation in the decay mode B→πγγB\to \pi \gamma \gamma

Within the framework of Standard Model, the exclusive decay mode $B\to \pi \gamma \gamma$ is studied. Although the usual short distance contribution is small compared to the similar $B\to K\gamma\gamma$ mode, the process offers the possibility of studying the CP violation, a feature absent in the $B \to K$ counterpart.Comment: 11 page latex file including 2 ps figures. Typos corrected, minor changes. To appear in PR

Possible large direct CP asymmetry in hadronic B+- -> \pi+- \eta' decays

We calculate the branching ratio and direct CP asymmetry in nonleptonic two body B decays B^+- ->\pi^+- \eta'. It is shown that the tree diagram and gluon fusion mechanism via penguin diagram have comparable contributions to these decays which, as a result, could provide an interesting venue for investigating CP violation. Our estimate shows that the direct CP asymmetry in the above decays could be as large as 75% which along with a branching ratio B(B^- ->\pi^- \eta')=3.4 X 10^{-6} should be accessible to experiment in the near future.Comment: 13 pages, Revtex, 4 figures (included

Dental Residents’ Knowledge and Attitude towards Stem Cells and Regenerative Dentistry

Objectives: Success of regenerative dental procedures highly depends on their acceptance by the clinicians; yet, little is known about dental residents’ attitudes regarding this new technology. The purpose of this study was to assess the knowledge and attitude of post-graduate dental students towards stem cells and regenerative dentistry as part of future dental treatments.Methods: This cross-sectional survey was conducted on 84 third-year residents of various dental specialties. The questionnaire included demographics and professional status of the respondents, questions regarding their ethical beliefs and their clinical practice.Results: Eighty-four completed questioners were returned anonymously. The majorities of the participants were female, and had practiced for ≤ 5 years. The survey showed that 76.2% of the participants had not received any continuing education or training courses on stem cells or regenerative dentistry. The majority of the participants (82.1%) believed that regenerative treatments should be included in dental practice. Of all, 76.2% had no umbilical cord or stem cell banking for themselves or a relative and 63.1% thought that dental pulp stem cell banking would be useful to regenerate dental tissues. Most of the participants (65.5%) had never performed regenerative therapy of any kind in their clinical practice and 51.2% of the participants were not sure whether regenerative procedures would be successful.Conclusion: Although more evidence on the efficacy and safety of regenerative dentistry is required, postgraduate training in this regard seems necessary

Batch studies on the removal of Ni (II) from aqueous solution by Azolla filiculoides

There are many plants which have the ability to accumulate large amounts of heavy metals and one of them is the aquatic fern, Azolla filiculoides. Toxic metals constitute a serious health risk because they accumulate in soils, water and organisms. One of the methods for removing these pollutants from water and soil is the use of plants. The aim of this study was to test the ability of A. filiculoides to adsorb Ni from polluted waters. The maximum uptake of nickel ions by the collected A. filiculoides biomass under the optimal conditions was approximately 45.32 mg/g dry Azolla. Desorption experiments indicated that EDTA was an efficient desorbent for recovery from nickel ions.Key words: Nickel, Azolla filiculoides, wastewater, biosorption

Inclusive dileptonic rare B decays with an extra generation of vector-like quarks

We investigate the leading effects of extending the Standard Model of electroweak interactions by an extra iso-singlet up- and down- type quark pair on various distributions and total branching ratio of the inclusive B-> X_s l^+ l^- (l =e,\mu) rare B decays. The presence of the extra vector-like down quark $D$ results in the non-unitarity of the extended quark mixing matrix V, which in turn leads to b-> s FCNC at the tree level proportional to (V^\dagger V)_{sb}. On the other hand, the effective penguin and box vertex functions are sensitive to the mass of the extra iso-singlet up quark m_U. The experimental upper bound on BR(B-> X_s \mu^+ \mu^-) is used to constrain the parameters of the model. It is shown that the shapes of the differential branching ratio and forward-backward asymmetry distribution are very sensitive to the value of the model parameters. We also calculate the CP aymmetry distribution of the dileptonic decay in the vector-like quark model. It is shown that, for a typical choice of the model parameters, asymmetries up to around 10% can be achieved for certain values of the dilepton invariant mass.Comment: 15 pages, 2 figure