Gas-liquid separator with integrated manifold as interface for HPLC-hydride AAS of organotin compounds

Summary A gas-liquid separator is presented, which is adapted to the special conditions of metalorganic speciation analysis by HPLC-hydride AAS.     

A boundary for reaction mechanisms within the transition metals interacting with nitrogen oxides is observed in DSIMS experiments

Summary Dynamic secondary ion mass spectrometry (DSIMS) investigations have been carried out with Cr, Mn, Fe, Co, Mo, Rh, W, Re, Os and Ir under 4 mPa N₂O, NO and 3 mPa NO₂ as reactant gases. Results indicate similar behaviour in adsorption for Cr, Mn, Fe, Mo, W on the one hand and for Co, Rh, Os and Ir on the other. For the first group of metals the nitrogen oxide molecules are always totally destroyed in adsorption whereas the second group shows evidence for surface compounds such as MeNO (Me=metal) indicating only a partial dissociation in the case of N₂O and NO₂, and molecular adsorption under NO respectively. Re does not belong uniquely to either group because it reacts with N₂O and NO₂ dissociatively whereas under NO only partial dissociation is observed.Abbreviations SIMS Secondary ion mass spectrometry - SSIMS Static SIMS - AES Auger electron spectroscopy - EELS Electron energy-loss spectroscopy - LEED Low energy electron diffraction - TDS Thermal desorption spectroscopy - XPS, UPS X-ray/Ultraviolet photoelectron spectroscopy     

Secondary ion emission of selected transition metals under nitrogen oxides

The emission of various positive secondary ions has been investigated for polycrystalline targets of Ti, V, Cr, Nb, Ta, Co, Ni, Cu, Pd and Pt, which were bombarded by Ar⁺ ions under dynamic SIMS (DSIMS) conditions in the presence of the gaseous nitrogen oxides N₂O, NO and NO₂ at fixed pressure and under residual gas. Besides ions of the Me⁺ type several fragmentary ions (e.g. N⁺, O⁺, NO⁺, MeN⁺ and MeO⁺) and also cluster ions Me _x O _y ⁺ (x 2, 0 y 2) were detected. Signals of a more molecular type with respect to the reactant gas, e.g. MeNO⁺, were only found for Co, Ni, Cu, Pd and Pt. From this, one may infer that for the other targets the nitrogen oxides will exist preferentially in a dissociatively adsorbed state at the metal surface. Several aspects of secondary ion emission can be explained assuming a different degree of oxidation for the metals under the influence of reactant gas.Part of the dissertation     

Cryopreservation by encapsulation of Gentiana spp cell suspensions maintains regrowth, embryogenic competence and DNA content

A reliable technique for cryopreservation by encapsulation was developed for two suspension cultures of gentian species (Gentiana tibetica and G. cruciata) of different ages and embryogenic potential. The effect of water content, aggregate size and the subculture time on viability was determined by the 2,3,5-triphenyltetrazolium chloride (TTC) test. Regrowth of a proembryogenic mass (PEM) on agar, liquid or agar/liquid media was assayed by measuring the increase in biomass. A water content of 24-30% (fresh weight basis) after 5-6 h dehydration of encapsulated cells of gentians yielded the highest survival (68% for G. tibetica and 83% for G. cruciata) after cryopreservation. Regardless of species, aggregate size and subculture time, the lowest PEM survival was 44%. These parameters did not influence the survival of G. tibetica PEM, but the survival of G. cruciata was higher when the smaller aggregates were cryopreserved on the 5th day of culture. Agar/liquid culture caused the greatest biomass increase. Cryopreservation did not affect the characteristics of suspension cultures and their regrowth after thawing, nor the number and dynamics of somatic embryos formed. Flow cytometry showed that cryopreservation did not change the genome size of the PEMs or regenerants.     

Influence of the primary ion incidence angle on secondary ion emission in SIMS with nitric oxide as reactant gas

Summary Secondary ion emission has been investigated for Ti, V, Cr and for Co, Ni and Cu under 9 mPa of NO as reactant gas with dynamic SIMS conditions. Using pivoted targets the relative intensities of various positive secondary ions were measured for varied incidence angles of the primary Ar⁺ ions (2 keV; 32 A·cm^–2). The axis of the PI beam and the axis of the SI detector were fixed rectangular to each other. The targets could be rotated about an axis perpendicular to both the PI and the detector axis. From the directional change of the emission of the metal ions Me⁺ a geometric shift parameter P_s could be deduced which proved to be related to the relative secondary ion yield and may therefore be used for surface characterization.     

Pressure dependence of secondary ion emission from selected 3d, 4d, and 5d transition metals under N2O, NO, and NO2

The reactant gas pressure dependence of secondary ion emission from surfaces of polycrystalline Cr, Fe, Co, Mo, Rh, W, Re, and Ir under the action of N₂O, NO and NO₂ was observed by means of moderate dynamic SIMS. The mass spectra for constant reactant gas pressure indicate the existence of two different groups of transition metals showing either dissociative or partial molecular adsorption behavior. This is confirmed at least above some suitable reactant gas pressure. Besides some special details (Fe/NO; Co/NO) several of the relative secondary ion intensities vs. reactant gas pressure exhibit similar curvature as for O₂, thus indicating the NO_x gases to be modified sources of oxygen. At higher pressures molecular secondary ions with and without metal atoms come to be appreciable. Received: 28 May 1997 / Revised: 2 February 1998 / Accepted: 4 February 1998     

Efficient nanocoax‐based solar cells

The power conversion efficiency of most thin film solar cells is compromised by competing optical and electronic constraints, wherein a cell must be thick enough to collect light yet thin enough to efficiently extract current. Here, we introduce a nanoscale solar architecture inspired by a well‐known radio technology concept, the coaxial cable, that naturally resolves this “thick–thin” conundrum. Optically thick and elec‐ tronically thin amorphous silicon “nanocoax” cells are in the range of 8% efficiency, higher than any nanostructured thin film solar cell to date. Moreover, the thin nature of the cells reduces the Staebler–Wronski light‐induced degradation effect, a major problem with conventional solar cells of this type. This nanocoax represents a new platform for low cost, high efficiency solar power. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

BODIPY dimers: structure,interaction, and absorption spectrum

Structural Chemistry - The object of the present study are BODIPY molecules obtained previously by Piskorz et al. (Dyes Pigm. 178:108322, 2020) for their antimicrobial activity. Structural analysis...     

Large hexagonal arrays of aligned ZnO nanorods

Large-scale truly periodic arrays of vertically aligned zinc oxide nanorods were grown on pre-patterned and pre-annealed gold dots on a-plane sapphire substrates via the vapor–liquid–solid mechanism. Periodic arrays of triangular gold islands were first patterned on the a-plane sapphire substrates by the nanosphere self-assembly technique. Zinc has been found to be an effective interfacial modifier between gold and sapphire to form single catalytic dots from triangular islands. The successful fabrication of zinc oxide nanowires in truly periodic arrays opens up the possibility of achieving enhanced room-temperature ultraviolet lasing and photonic crystal based devices and sensors. PACS 81.07.Bc; 81.10.-h; 81.16.Nd