Bi-large neutrino mixings by radiative magnification

Starting with the unification hypothesis of mixings of quarks and leptons and small quark-like mixings at the see-saw scale, we find that two large mixings for ν_e —νx03BC; andv _μ—v _τ at the weak scale are obtained as a result of renormalization group evolution and radiative magnification if the three neutrinos are quasi degenerate in masses and possess the same CP parity. We also find thatU _e3 remains small and well within the CHOOZ-Palo Verde bound since the correspondingV _ub for CKM mixing is very small. Several testable pedictions are pointed out.     

A mild deprotection strategy for allyl-protecting groups and its implications in sequence specific dendrimer synthesis

A mild deprotection strategy for allyl ethers under basic conditions in the presence of a palladium catalyst is described. Under these conditions, aryl allyl ethers can be cleaved selectively in the presence of alkyl allyl ethers. These conditions are also effective in the deprotection of allyloxycarbonyl groups. The utility of the current methodology in sequence specific dendrimer synthesis is demonstrated.     

Reaction of ethyl bromoacetate with substituted naphthoate ions

Rate constants for the reaction of ethyl bromoacetate with three series of substituted naphthoate ions have been measured in an acetone-water mixture (90% v/v). Using σ _p values rate constants at 30^o correlate well with the Hammett equation yielding ρ=−0.54, −0.19 and −0.25 for (4,1−), (6,1−) and (6,2−) series, respectively. Comparison of these ρ values with those of the reaction of phenacyl bromide reveals the failure of the reactivity-selectivity principle RSP in these reactions. Failure of RSP has been explained in terms of isoselective temperature.     

Influence of Hydrogen Bond on Thermal and Phase Transitions of Binary Complex Liquid Crystals

A novel supramolecular liquid crystal (LC) is synthesized from the binary complex of 4-decyloxy benzoic acid and cholesteryl acetate. Fourier transform infrared (FTIR) spectroscopic study confirms the formation of intermolecular hydrogen bond between the mesogens. Various mesophases and corresponding textural changes in the complex are observed by comparing with its constituents through polarizing optical microscopic (POM) studies. The thermal stability factor of smectic phase for present complex is calculated. An interesting observation of present work is that investigation of extended thermal span of mesomorphic phases, decreased enthalpy, a nematic phase with a high clearing point and a low melting point. This is due to an arrangement of molecular reorientations and the development of new associations by hydrogen bonding. Optical tilt angle for smectic C phase is determined and the same is fitted to a power law.     

Rh2(OAc)4 catalyzed substrate selective [4+2]/[2+2] cycloaddition of acylketenes: a highly chemo- and regioselective synthesis of spiro(oxindolyl)oxazinones and β-lactams

A rhodium(II) catalyzed [4+2]/[2+2] cycloaddition reaction of N-protected isatin-3-arylimine with acylketene derived from α-diazocarbonyl compounds has been achieved for the first time for the preparation of a novel class of spiro(oxindolyl)oxazinone and spiro(oxindolyl)-β-lactam derivatives.     

Radiative decays,photoproduction and total cross section of theψ particles

It is pointed out that the coupling characterizing theψ-γ vertex must change substantially between the limits,ψ on mass-shell which occurs inψ→e ⁺ e ⁻ and photon on mass-shell which is relevant in radiative decays likeψ→ππγ, ψ→ηγ and photoproduction ofψ. This has the consequence that the value ofψN total cross section must be larger than what is inferred from the use of naive vector dominance in photoproduction.     

Validity of the equivalent-photon approximation for the production of massive spin-1 particles

We point out that the equivalent-photon approximation (EPA) for processes with massive spin-1 particles in the final state would have validity in a more restricted kinematic domain than for processes where it is commonly applied, viz., those with spin-1/2 or spin-0 particles in the final state. We obtain the criterion for the validity ofEPA for the two-photon production of a pair of charged, massive, point-like spin-1 particlesV ^±, each of massM and with a standard magnetic moment (κ=1). In a process in which one of the photons is real and the other virtual with four-momentumq, the condition for the validity ofEPA is |q ²|≪M ², in addition to the usual condition |q ²|≪W ²,W being theV ⁺ V ⁻ invariant mass. In a process in which both photons are virtual (with four-momentaq andq′), our condition is |q ²||q′²|W ⁴ ≪ 16M ⁸, in addition to |q ²| ≪M ², |q′²| ≪M ² and |q ²| ≪W ², |q′²| ≪W ². Even when these extra conditions permitting the use ofEPA are not fulfilled, convenient approximate expressions may still be obtained assuming merely |q ²| ≪W ² and |q′²| ≪W ². We also discuss how the extra conditions are altered when the vector bosons are incorporated in a spontaneously broken gauge theory. Examples ofW boson production in Weinberg-Salam model are considered for which the condition |q ²||q′²|W ⁴ ≪ 16M ⁸ is shown to be removed.     

Studies on electron transfer reactions: reduction of heteropoly 10-tungstodivanadophosphate by <Emphasis Type="SmallCaps">l</Emphasis>-cysteine in aqueous acid medium

l-cysteine undergoes facile electron transfer with heteropoly 10-tungstodivanadophosphate, [ \textPV^\textV \textV^\textV \textW _{1 0} \textO _{4 0} ]^{5 -} , \left[ {{\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} } \right]^{5 - } , at ambient temperature in aqueous acid medium. The stoichiometric ratio of [cysteine]/[oxidant] is 2.0. The products of the reaction are cystine and two electron-reduced heteropoly blue, [PV^IVV^IVW₁₀O₄₀]⁷⁻. The rates of the electron transfer reaction were measured spectrophotometrically in acetate–acetic acid buffers at 25 °C. The orders of the reaction with respect to both [cysteine] and [oxidant] are unity, and the reaction exhibits simple second-order kinetics at constant pH. The pH-rate profile indicates the participation of deprotonated cysteine in the reaction. The reaction proceeds through an outer-sphere mechanism. For the dianion ⁻SCH₂CH(NH₃ ⁺)COO⁻, the rate constant for the cross electron transfer reaction is 96 M⁻¹s⁻¹ at 25 °C. The self-exchange rate constant for the ^- \textSCH₂ \textCH( \textNH₃ ⁺ )\textCOO ^- \mathord