Synthesis of thiol-capped gold nanoparticle with a flow system using organosilane as a reducing agent

Synthesis of thiol-capped gold nanoparticle is carried out by mixing of a THF solution of HAuCl₄·4H₂O and ⁿC₁₂H₂₅SH with a THF solution of triethylsilane in a flow system that consists of polytetrafluoroethylene tubing. The effect of residence time and reaction temperature on the particle size is examined.     

Selective monobenzoylation of 1,2- and 1,3-diols catalyzed by Me2SnCl2 in water (organic solvent free) under mild conditions

We have developed an efficient method for selective monobenzoylation of 1,2- and 1,3-diols in water catalyzed by Me(2)SnCl(2). Treatment of 1,2- and 1,3-diols with benzoyl chlorides, DMT-MM, and potassium carbonate in the presence of a catalytic amount of Me(2)SnCl(2) and DMAP in water at room temperature gave monobenzoates in up to 97% yield.     

An economical approach for peptide synthesis via regioselective C–N bond cleavage of lactams

An economical, solvent-free, and metal-free method for peptide synthesis via C–N bond cleavage using lactams has been developed. The method not only eliminates the need for condensation agents and their auxiliaries, which are essential for conventional peptide synthesis, but also exhibits high atom economy. The reaction is versatile because it can tolerate side chains bearing a range of functional groups, affording up to >99% yields of the corresponding peptides without racemisation or polymerisation. Moreover, the developed strategy enables peptide segment coupling, providing access to a hexapeptide that occurs as a repeat sequence in spider silk proteins.

An economical, solvent-free, and metal-free method for peptide synthesis via C–N bond cleavage using lactams has been developed.     

Synthesis and Aromaticity of Benzene-Fused Doubly N-Confused Porphyrins

A bicyclo[2.2.2]octadiene(BCOD)-fused bis(dipyrromethane) derivative was reacted with methylal in the presence of trifluoroacetic acid followed by oxidation with chloranil to give a doubly N-confused phlorin derivative, which did not undergo the retro-Diels–Alder reaction extruding an ethylene molecule on heating. In contrast, a 7-tert-butoxybicyclo[2.2.1]heptadiene(7-BuOBCHD)-fused bis(dipyrromethane) yielded benzene-ring-fused doubly N-confused porphyrins by following similar reaction sequences.     

Synthesis of novel 3-(α-arylhydrazono-1,3,4-oxadiazol-2-ylmethyl)-2-oxo-1,2-dihydroquinoxalines and their characteristic tautomerism between the hydrazone imine and diazenyl enamine forms

The reactions of 3-(α-arylhydrazono)hydrazinocarbonylmethyl-2-oxo-1,2-dihydroquinoxalines 1a,b with triethyl orthoesters resulted in the intramolecular cyclization to give the 3-(α-arylhydrazono-1,3,4-oxadiazol-2-ylmethyl)-2-oxo-1,2-dihydroquinoxalines 4a–d , but not the 1,2,4,5-tetrazepinylquinoxalines 5a–d . The cyclization mode into the 1,3,4-oxadiazole ring was confirmed by the alternate syntheses of 4a,c from the reactions of 3-(1,3,4-oxadiazol-2-ylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxalines 6a,b with o-chlorophenyl diazonium salts, respectively. Moreover, 4a–d exhibited an interesting tautomerism between the hydrazone imine form A and diazenyl enamine form B.     

Aggregating pattern dynamics in a chemotaxis model including growth

A population model including diffusion, chemotaxis and growth is studied. Assuming that the diffusion rate and the chemotactic rate are both very small compared with the growth rate, we derive a new equation to describe the time-evolution of the aggregating region of biological individuals and show the conditions for the existence and stability of radially symmetric equilibrium solutions of the equation, which indicate the aggregation of individuals.     

An affine scaling method with an infeasible starting point: Convergence analysis under nondegeneracy assumption

In this paper, we propose an infeasible-interior-point algorithm for linear programning based on the affine scaling algorithm by Dikin. The search direction of the algorithm is composed of two directions, one for satisfying feasibility and the other for aiming at optimality. Both directions are affine scaling directions of certain linear programming problems. Global convergence of the algorithm is proved under a reasonable nondegeneracy assumption. A summary of analogous global convergence results without any nondegeneracy assumption obtained in [17] is also given.     

Thermoosmosis of various electrolyte solutions through anion-exchange membranes

Thermoosmosis through anion-exchange membranes was measured for 10^-3 to 2 mol/kg of aqueous KCl, LiCl, and NH₄Cl and for 10^-3 to 3 x 10^-1 mol/kg of aqueous KIO₃ and K₂SO₄. For all electrolytes used the direction of thermoosmosis was from the cold side to the hot side over the whole range of concentrations. For KCl and LiCl the experimental results were analyzed with an extension of a previously published theory, using additional data for transport numbers of ions in membranes and for electroosmosis. The agreement between theory and experiment is satisfactory. The absolute value of thermoosmosis for KIO₃ is larger than that for other electrolytes because the pore volume fraction of the membrane for KIO₃ is larger than that for the other electrolytes.     

核磁共振碳谱的研究:烷烃分子的化学位移δ与原子距边矢量μ

系统研究了核磁共振碳谱及其化学位移规律性。并提出了一种新的分子图论参数：原子距离－边数矢量（μ矢量），并发现它与烷烃的１３－ＣＮＭＲ有良好的相关性。