New design of a radio-frequency plasma torch

A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a radio-frequency (rf) plasma torch. The method employed here is based on Boulos' model with the exception of the boundary conditions for the electric and magnetic field equations. Calculations have been made for the confirmation of a new sample injection method, which is capable of completely evaporating refractory materials at high feeding rates without interfering with the stability of the plasma. In the newly designed torch, the reagent is radially injected into the hottest part of the plasma through quartz capillary tubes set symmetrically between an inductor coil. Experimental investigations have also been performed for verifying the proper function of the design. These results provide evidence that our radial injection method developed here is more effective in practical processing than the conventional axial injection methods.     

Fundamental aspects of electrospray droplet impact/SIMS

A new ionization method, electrospray droplet impact ionization (EDI), has been developed for matrix-free secondary-ion mass spectrometry (SIMS). The charged droplets formed by electrospraying 1 M acetic acid aqueous solution are sampled through an orifice with a diameter of 400 microm into the first vacuum chamber, transported into a quadrupole ion guide, and accelerated by 10 kV after exiting the ion guide. The droplets impact on a dry solid sample (no matrix used) deposited on a stainless steel substrate. The secondary ions formed by the impact are transported to a second quadrupole ion guide and mass-analyzed by an orthogonal time-of-flight mass spectrometer (TOF-MS). Ten pmol of gramicidin S could be detected with the presence of as much as 10 nmol of NaCl. The ion signal for arginine disappeared with decrease in the substrate temperature below 150 K owing to the formation of ice film over the sample surface. While 10 fmol of gramicidin S could be detected for 30 min, the ionization/desorption efficiency for EDI becomes smaller with an increase in the molecular weight (MW) of a biological sample. The largest protein samples detected to date are cytochrome c and lysozyme. The high sensitivity for EDI is due to the fact that samples only a few monolayers thick are subject to desorption/ionization by EDI, with little fragmentation. A coherent phonon excitation may be the main mechanism for the desorption/ionization of the solid sample.     

Mass migration on a polymer surface caused by photoinduced molecular rotation

We demonstrated the formation of a photoinduced surface relief grating using thin films comprising a photochromic molecular motor, 9-(2-phenyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene. Results show that mass migration occurred by patterned light irradiation prepared from interfered laser beams and a photomask.     

Carbon Dioxide: A Peagent for the Protection of Nucleophilic Centres and the Simultaneous Activation to Electrophilic Attack-Part Xii. One-Pot Conversion of 3-Methylindole into 2-Formyl-3-Methylindole

3-Methylindole is converted via treatment of intermediate lithium 2-lithio-3-methylindole-l-carboxylate with dimethylformamide or methyl formate, as formylating agent, into 2-formyl-3-methylindole in 54% overall yield in a one-pot procedure.     

Synthesis of glycosylcurcuminoids

Condensation of glycosylated arylaldehyde with acetylacetone-B(2)O(3) complex gave a corresponding diglycosylcurcuminoid, and a similar reaction using a mixture of arylaldehyde and glycosylarylaldehyde gave an unsymmetrical monoglycosylcurcuminoid, both as boron-complexes. The boron was removed from the complexes by heating in methanol, thus achieving the synthesis of di- and mono-glycosylcurcuminoids.     

Organocatalytic direct asymmetric aldol reactions in water

We have developed direct asymmetric cross-aldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These results reveal an effective design strategy for the development of aqueous organocatalytic systems.     

Alkynyl derivatives of gold complexes containing C6H3-5-Me-2-EPh2 (E = P, As) ligands

[Au₂Cl₂{μ-2,2′-Ph₂As(5,5′-Me₂C₆H₃C₆H₃)AsPh₂}] reacts with phenylacetylene or ethynylferrocene to give the corresponding digold(I) bis(alkynyl) derivatives [Au₂(CCR)₂{μ-2,2′-Ph₂As(5,5′-Me₂C₆H₃C₆H₃)AsPh₂}] [R = Ph (4), Fc (5)]. In contrast, products resulting from the reaction with 1,3- or 1,4-diethynylbenzene (deb) depend markedly on the dichlorodigold(I) complex to ligand ratio. When an excess of alkyne is used, the expected bis(alkynyl) complexes [Au₂X₂{μ-2,2′-Ph₂As(5,5′-Me₂C₆H₃C₆H₃)AsPh₂}] [X = 1,3-deb (6), 1,4-deb (7)] are obtained, but when using a 1:1 molar ratio poorly soluble, presumably polymeric, species are formed. Attempts to prepare a digold(II) bis(alkynyl) derivative by treatment of [Au₂Cl₂(μ-C₆H₃-5-Me-2-PPh₂)₂] with ethynylferrocene in the presence of NaOMe gives a mixture of species, the recrystallization of which yielded a crystal of [{2-(FcCC)-4-MeC₆H₃PPh₂}Au(CCFc)] (1). The reaction of [Au₂Cl₂(μ-C₆H₃-5-Me-2-AsPh₂)₂] with phenylacetylene, 1,3- or 1,4-deb gives a mixture of unidentified products.     

Effective UV photolytic decomposition of organic compounds with a low-pressure mercury lamp as pretreatment for voltammetric analysis of trace metals

The effectivity of UV irradiation with low and high pressure mercury (L-Hg and H-Hg) lamps on the decomposition of organic compounds in aqueous solutions, as pretreatment for the voltammetric determination of trace metals, is compared. The photolytic decomposition with the L-Hg lamp was much faster than with the H-Hg lamp. The higher efficiency of the L-Hg lamp is caused by its greater light intensity at short wavelengths. Interferences of organic compounds on the voltammetric determination of nickel and indium were eliminated successfully by 90 min irradiation with the L-Hg lamp. Humic acid and organic interference with the voltammetric determination of nickel in natural river water were successfully eliminated. The decomposition using the L-Hg lamp can be carried out without added oxidizing reagents and at room temperature, thus eliminating loss of water samples by evaporation at higher temperature.     

Circularly polarized luminescence of rhodamine B in a supramolecular chiral medium formed by a vortex flow

Sucked into the vortex: Hydrogels with embedded Rhodamine?B dye showed stir-induced circularly polarized luminescence (CPL; see picture), the sense of which can be controlled by switching the stir direction from clockwise (CW) to counterclockwise (CCW) with slow cooling from the sol to gel states. The chiral alignment of the dye was erased by heating the sample above the gel-sol transition temperature.