Application of proton induced X-ray emission to the qualitative and quantitative analysis of iodine in biological samples

Particle-induced X-ray emission (PIXE) was applied to evaluate the loss of volatile elements such as iodine in biological samples. The analytical quality of the method is comparable or better than spectrophotometry, which is currently believed to be the most reliable for iodine determination. The temperature dependence of volatility loss of trace iodine was characteristic, and the feature was divided into three temperature regions. The first one, ranging from room temperature to 200 °C, showed only a slight loss below 20% on drying; the second stage, between 200 °C and 350 °C, where carbonizing processes became prominent, showed a remarkable loss up to 50%; the last one, beyond 350 °C, was accompanied by a considerable loss of iodine (more than 80%) with ashing. Even in the analysis using low temperature ashing with oxygen plasma, the loss of iodine observed was considerable (nearly 80%). The significance of these findings by PIXE in trace analysis is noted to improve analytical quality of volatile elements, such as iodine in biological, medical and also environmental fields.     

Photo-induced dimerization of 1-naphthoxide anion: Electron transfer mechanism

Irradiation of sodium 1-naphthoxide in MeOH gave selectively 1,4-dihydro-4',8-dihydroxy-1,1'-binaphthyl 2. A similar reaction in PhH afforded the regioisomer 5, along with 6, Structural proof is presented for these hitherto unknown dimers. The reaction is completely quenched in the presence of naphthalene, a good electron scavenger. This new type of photodimerization was proved to be initiated by intermolecular electron-transfer from the excited 1-naphthoxide anion to the ground state one to give the oxidation-reduction dimers.     

Mechanism of external heavy-atom enhancement of the radiative transition rate from the π,π* triplet state

The effect of external heavy-atom perturbation is examined for each of the three spin subcomponents of the π,π^* triplet state. It is shown that the radiative decay rate from the subcomponent whose spin wavefunction is within the molecular plane is most effectively enhanced. The main perturbing singlet state is the charge-transfer state arising from the excitation of an electron from a π orbital of the molecule to the σ^* orbital of the perturber.     

Chemical behaviour of helium muonide just after muon catalyzed fusion

Chemical behaviour of a helium muonide atom /He^o/ can be understood on the analogy of its hydrogen homologues, muonium /Mu/, deuterium /D^o/ and tritium /T^o/. In muon catalyzed fusion /CF/, a small fraction of negative muon in the fusion cycle sticks to helium to give proton-like He⁺ which easily picks up one electron forming He^o. The energy of He⁺ at birth is about 3.5 MeV being in a similar situation to the case of a hot tritium atom produced by /n, p/ or /n, / reaction. The reaction cross section and rate of He^o reactions are estimated.     

Metal-ion-assisted hydrolysis of dipeptides involving a serine residue in a neutral aqueous solution

Dipeptides having a serine residue at the C-terminus, X-Ser, where X is an appropriate amino acid residue, were efficiently hydrolyzed in the presence of ZnCl2 at pH 7.0. The rapid hydrolysis of X-Ser is due to an autocatalysis of the hydroxy group in the serine residue, and is found to be accelerated by a metal ion, in particular by ZnCl2. Roles of the metal ion in the hydrolysis of peptides involving a serine residue, in relation to the recently reported protein cleavages, are discussed.     

Radical Copolymerization of Vinylidene Chloride with 3(2-Methyl)-6-methylpyridazinone in Several Solvents

The radical copolymerization of vinylidene chloride (Vc, M₁) with 3(2-methyl)-6-methylpyridazinone (I, M₂) was carried out in benzene, ethanol, phenol, and acetic acid at 60 and 80°C. The monomer reactivity ratios were found to vary with the reaction conditions. The linear correlationships were obtained by plotting the values of log r₁ against those of ^V C[dbnd]O and ^V C[dbnd]C of monomers determined in the solvents.     

Sharp Morawetz estimates

We prove sharp Morawetz estimates — global in time with a singular weight in the spatial variables — for the linear wave, Klein-Gordon, and Schrödinger equations, for which we can characterise the maximisers. We also prove refined inequalities with respect to the angular integrability.     

Formal (4+1) Cycloaddition and Enantioselective Michael–Henry Cascade Reactions To Synthesize Spiro[4,5]decanes and Spirooxindole Polycycles

Spiro[4,5]decanes and polycyclic compounds bearing spiro[4,5]decane systems are important biofunctional molecules. Described are diastereoselective formal (4+1) cycloaddition reactions to afford oxindole-functionalized spiro[4,5]decanes and organocatalytic enantioselective Michael–Henry cascade reactions of the (4+1) cycloaddition products to generate spirooxindole polycyclic derivatives bearing the spiro[4,5]decane system. Spiro[4,5]decanes bearing oxindoles containing three stereogenic centers and spirooxindole polycycles having seven stereogenic centers, including two all-carbon chiral quaternary centers and one tetrasubstituted chiral carbon center, were obtained with high diastereo- and enantioselectivities.     

Applications of Clifford’s Geometric Algebra

We survey the development of Clifford’s geometric algebra and some of its engineering applications during the last 15 years. Several recently developed applications and their merits are discussed in some detail. We thus hope to clearly demonstrate the benefit of developing problem solutions in a unified framework for algebra and geometry with the widest possible scope: from quantum computing and electromagnetism to satellite navigation, from neural computing to camera geometry, image processing, robotics and beyond.