New Visible Light-triggered Photocatalytic Trifluoromethylation Reactions of Carbon‐carbon Multiple Bonds and (Hetero)aromatic Compounds

Visible-light-photocatalyzed methods employed insynthetic transformations present attractive properties such asenvironmentally friendly, safety, availability and excellent functionalgroup tolerance. In this venue, research on the visible-lightphotocatalytic incorporation of the trifluoromethyl CF3 moiety intoorganic substrates, in particular, has contributed to a clear evolutionof the very field of photocatalysis. Outer-sphere electron transfersbetween photocatalysts and trifluoromethyl sources supply CF3radicals efficiently in clean and controlled ways, capable of effectingnumerous synthetic transformations and functionalization on organicsubstrates and compounds with pharmacological activity instraightforward manners. Although this particular area is constantlyevolving and reviewed, the last five years have experienced anoutburst of seminal and significant photocatalytic trifluoromethylationexamples that are leading the way and opening new syntheticavenues. Recent review articles on Ru- and Ir- based photocatalytictrifluoromethylation reactions have borne witness of this evolution.Although this account will show the new Ru- and Ir-basedphotocatalytic trifluoromethylations, Sections 2 and 3 will alsoillustrate other photocatalytic systems, such as organic dyes, organicsemiconductors and newly-developed all-organic photocatalysts. All the known and reviewed strategies for photocatalytictrifluoromethylation reactions of olefins and (hetero)aromaticcompounds will not be discussed but will be summarized in twoFigures (Figures 4 and 5), and new examples (2015-present) will bepresented and discussed.Fil: Barata Vallejo, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; ArgentinaFil: Postigo, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin

Stau relic density at the Big-Bang nucleosynthesis era consistent with the abundance of the light element nuclei in the coannihilation scenario

We calculate the relic density of stau at the beginning of the Big-Bang Nucleosynthesis (BBN) era in the coannihilation scenario of minimal supersymmetric standard model (MSSM). In this scenario, stau can be long-lived and form bound states with nuclei. We put constraints on the parameter space of MSSM by connecting the calculation of the relic density of stau to the observation of the light elements abundance, which strongly depends on the relic density of stau. Consistency between the theoretical prediction and the observational result, both of the dark matter abundance and the light elements abundance, requires the mass difference between the lighter stau and the lightest neutralino to be around 100MeV, the stau mass to be 300 -- 400 GeV, and the mixing angle of the left and right-handed staus to be $\sin\theta_{\tau} = (0.65 \textrm{--} 1)$.Comment: 9 pages, 5 figures, figure 5 correcte

Non-Abelian Medium Effects in Quark-Gluon Plasma

Based on the kinetic theory, the non-Abelian medium property of hot Quark-Gluon Plasma is investigated. The nonlinearity of the plasma comes from two aspects: The nonlinear wave-wave interaction and self-interaction of color field. The non-Abelian color permittivity is obtained by expanding the kinetic equations to third order. As an application, the nonlinear Landau damping rate and the nonlinear eigenfrequency shift are calculated in the longwave length limit.Comment: 12 pages(Revtex), no figure

Big-bang nucleosynthesis with a long-lived charged massive particle including 4^4He spallation processes

We propose helium-4 spallation processes induced by long-lived stau in supersymmetric standard models, and investigate an impact of the processes on light elements abundances. We show that, as long as the phase space of helium-4 spallation processes is open, they are more important than stau-catalyzed fusion and hence constrain the stau property.Comment: 12 pages, 4 figures, 1 table, references added, all figures correcte

Investigation of passive flow control techniques to enhance the stall characteristics of a microlight aircraft

This report investigates the enhancement of aerodynamic stall characteristics of a Skyranger microlight aircraft by the use of passive flow control techniques, namely vortex generators and turbulators. Each flow control device is designed and scaled to application conditions. Force balance measurements and surface oil flow visualisation are carried out on a half-model of the microlight to further investigate the nature of the flow on the aircraft with and without the flow control devices. The results indicate a clear advantage to the use of turbulators compared with vortex generators. Turbulators increased the maximum lift coefficient by 2.8%, delayed the onset of stall by increasing the critical angle by 17.6% and reduced the drag penalty at both lower (pre-stall) and higher angles of attack by 8% compared to vortex generators. With vortex generators applied, the results indicated a delayed stall with an increase in the critical angle by 2% and a reduced drag penalty at higher angles of attack

Real Space Imaging of Spin Polarons in Zn Doped SrCu2(BO3)2

We report on the real space profile of spin polarons in the quasi two-dimensional frustrated dimer spin system SrCu2(BO3)2 doped with 0.16% of Zn. The 11B nuclear magnetic resonance spectrum exhibits 15 additional boron sites near non-magnetic Zn impurities. With the help of exact diagonalizations of finite clusters, we have deduced from the boron spectrum the distribution of local magnetizations at the Cu sites with fine spatial resolution, providing direct evidence for an extended spin polaron. The results are confronted with those of other experiments performed on doped and undoped samples of SrCu2(BO3)2.Comment: 9 pages, 11 figures, including supplemental materials. accepted for publication in PR

Quantitative assessment of people-oriented forestry in Bangladesh: A case study in the Tangail forest division

ArticleJOURNAL OF ENVIRONMENTAL MANAGEMENT. 88(1): 83-92 (2008)journal articl

Avoiding zero probability events when computing Value at Risk contributions

This paper is concerned with the process of risk allocation for a generic multivariate model when the risk measure is chosen as the Value-at-Risk (VaR). We recast the traditional Euler contributions from an expectation conditional on an event of zero probability to a ratio involving conditional expectations whose conditioning events have stricktly positive probability. We derive an analytical form of the proposed representation of VaR contributions for various parametric models. Our numerical experiments show that the estimator using this novel representation outperforms the standard Monte Carlo estimator in terms of bias and variance. Moreover, unlike the existing estimators, the proposed estimator is free from hyperparameters