Efficient Solid/Liquid Phase-Transfer Catalytic Diazo Transfer Synthesis

A simple and efficient solid/liquid phase-transfer catalytic diazo transfer reaction for the synthesis of diazocarbonyl, diazophosphonyl, and diazophosphinyl compounds is reported.     

Dibromomethane as One‐Carbon Source in Organic Synthesis: Formal Total Synthesis of (±)‐Nephrosteranic Acid

A diastereoselective formal total synthesis of (±)‐nephrosteranic acid (10) is described. The key step is to introduce the α‐methylene group by the ozonolysis of monosubstituted alkenes followed by reaction with a preheated mixture of CH₂Br₂–Et₂NH. The α‐methyl group of compound 10 was formed from the reduction of the corresponding α‐methylene precursor.     

Discriminant analysis of prion sequences for prediction of susceptibility

Prion diseases, including ovine scrapie, bovine spongiform encephalopathy (BSE), human kuru and Creutzfeldt–Jakob disease (CJD), originate from a conformational change of the normal cellular prion protein (PrP^C) into abnormal protease-resistant prion protein (PrP^Sc). There is concern regarding these prion diseases because of the possibility of their zoonotic infections across species. Mutations and polymorphisms of prion sequences may influence prion-disease susceptibility through the modified expression and conformation of proteins. Rapid determination of susceptibility based on prion-sequence polymorphism information without complex structural and molecular biological analyses may be possible. Information regarding the effects of mutations and polymorphisms on prion-disease susceptibility was collected based on previous studies to classify the susceptibilities of sequences, whereas the BLOSUM62 scoring matrix and the position-specific scoring matrix were utilised to determine the distance of target sequences. The k-nearest neighbour analysis was validated with cross-validation methods. The results indicated that the number of polymorphisms did not influence prion-disease susceptibility, and three and four k-objects showed the best accuracy in identifying the susceptible group. Although sequences with negative polymorphisms showed relatively high accuracy for determination, polymorphisms may still not be an appropriate factor for estimating variation in susceptibility. Discriminant analysis of prion sequences with scoring matrices was attempted as a possible means of determining susceptibility to prion diseases. Further research is required to improve the utility of this method.     

Size tuned electrophoretic pyrazoline nanoparticles prepared through dispersion-polymerization

Highly monodispersed electrophoretic particles of size ranging from 550 to 160 nm could be prepared through dispersion-polymerization of methyl methacrylate and ethylene glycol dimethacrylate in presence of pyrazoline nanoparticles in a methanol-water mixture. The size of the fabricated electrophoretic particles could be controlled by adjusting the concentration of surfactant. Stearic acid, used as surfactant during the polymerization process also acts as charge controlling additive to control the electrophoric mobility of the particles. Maximum electrophoric mobility (-7.513×10(-5) cm(2)/Vs) was obtained for the 400 nm electrophoretic particles prepared with 1.5 wt.% of stearic acid surfactant. The electrophoric display cells prepared with our electrophoretic particles reveal good current voltage characteristics and color change under applied bias voltage.     

The synthesis and spectral properties of a stimuli-responsive D–π–A charge transfer dye based on indole donor and 2-cyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran acceptor moieties

A particular chromogenic and fluorophoric dye chemosensor was designed and synthesized, which was based on the stimuli-responsive D–π–A charge transfer system. Indole moiety as a donor unit and furan moiety as an acceptor unit were used. This prepared dye sensor showed the selective fluoride ion sensing effects in UV–vis absorption and fluorescence emission properties. Clear absorption changes and highly selective fluorescence quenching effects with fluoride ion were determined. Experimental data and images were collected and supported to provide a better understanding of this particular dye sensor.     

Gauged Lifshitz scalar field theories in two dimensions

We present two-dimensional gauged Lifshitz scalar field theories by considering the duality relation between the source current and the Noether current. Requiring the duality partially, we obtain a gauged model which recovers the bosonized Schwinger model for the IR limit. For the exact duality, however, the source current is not conserved, which means that the resulting theory is anomalous, so that the number of degrees of freedom is increased. The second model is consistently formulated by adding the Wess–Zumino type action to maintain the gauge invariance.     

Magnetic ordering in the frustrated system FeSc2S4

The sample of FeSc₂S₄ was prepared by solid reaction method. The crystallographic structure and the magnetic properties of the fabricated compound were investigated by X-ray, and superconducting quantum interference device (SQUID) magnetometer and Mössbauer spectroscopy. The polycrystalline FeSc₂S₄ confirmed the normal cubic spinel structure (space group Fd3m). The lattice constants a₀ and anion parameter u are 10.519 Å and 0.255, respectively. The Mössbauer spectroscopy has been studied for the FeSc₂S₄ at various temperatures, ranging from 4.2 K to room temperature. The spectra consist of two doublets at 4.2 K while a single line at room temperature. It is noticeable that the Mössbauer spectra of two doublet patterns with large electric quadrupole splitting (ΔE_Q) remain over the Néel temperature. Those are interpreted as a result of large electric quadrupole interaction compared to magnetic dipole interaction. The magnetic susceptibility measurements were performed with a SQUID magnetometer for temperatures 2<T<320 K, in external fields up to 5 kOe. Magnetic behavior shows antiferromagnetic behavior and the magnetic superexchange interactions between the Fe ions are weakly antiferromagnetic. The paramagnetic susceptibilities follow Curie–Weiss (CW) law with CW temperature Θ_CW=−100 K, and frustration parameter f=−Θ_CW/T_N is of the order of 1000. We conclude that two sublattices are coupled antiferromagnetically, leading to strong frustration effects.     

Entropy of the FRW cosmology based on the brick wall method

The brick wall method in calculations of the entropy of black holes can be applied to the FRW cosmology in order to study the statistical entropy. An appropriate cutoff satisfying the covariant entropy bound can be chosen so that the entropy has a definite bound. Among the entropy for each of cosmological eras, the vacuum energy-dominated era turns out to give the maximal entropy which is in fact compatible with assumptions from the brick wall method.     

Fluorescence Properties of Dibenzofluorescein in Aqueous Solution

The deprotonation of dibenzofluorescein (DBFL), a long wavelength fluorescence probe, results in the simultaneous occurrence of neutral form, monoanion and dianion under physiological conditions. The fluorescence properties of the former two cannot be measured directly because they are always coexistent with some other species. By measuring the fluorescence under various pHs we computed the fluorescence parameters for each species involved in the prototropic equilibria of DBFL, including each species’ emission spectrum, excitation spectrum, emission and excitation maximum, fluorescence quantum yield and lifetime. It was found that the monoanion is the most fluorescent chromospheres (Φ _f = 0.66, compared to Φ _f = 0.25 for dianion, 0.18 for cation and 0.0 for the neutral form). Together with the computed pK _as, we are able to suggest that the monoanion plays a major role under physiological conditions when DBFL is used as a fluorescence probe, contrary to the assumption in literature.     

Decay rate ratios of \varUpsilon (5S)\to B{\bar{B}} reactions

We calculate the decay rate ratios for OZI allowed decays of ?(5S) to two B mesons by using the decay amplitudes which incorporate the wave function of the ?(5S) state. We obtain the result that the branching ratio of the ?(5S) decay to $B_{s}^{*}{\bar{B}}_{s}^{*}$ is much larger than the branching ratio to $B_{s}{\bar{B}}_{s}^{*}$ or ${\bar{B}}_{s}B_{s}^{*}$ , in good agreement with the recent experimental results of CLEO and BELLE. This agreement with the experimental results is made possible since the nodes of the ?(5S) radial wave function induce the nodes of the decay amplitude. We find that the results for the ?(5S) decays to $B_{u}^{(*)}{\bar{B}}_{u}^{(*)}$ or $B_{d}^{(*)}{\bar{B}}_{d}^{(*)}$ pairs are sensitive to the parameter values used for the potential between heavy quarks.