Future perspective of nanoparticle interaction‐assisted laser desorption/ionization mass spectrometry for rapid,simple, direct and sensitive detection of microorganisms

The introduction of nanoparticles into mass spectrometric research greatly influenced the applicability of this technique into various omics. Surface‐modified or functionalized nanoparticles (NPs) have recently extended the use of mass spectrometry into microorganism research. We survey the application of unmodified NPs, for microorganism research, on the basis of our expertise in this area within the recent years in this decade. The use of unmodified NPs in mass spectrometry, especially with respect to microorganisms, is an untreaded research area, which we have ventured to probe and have been fruitful. On the basis of our experience, we provide an insight into the principle behind the use of unmodified NPs and provide guidelines to be followed to obtain significant results. We also brief the current scenario of nanoparticle interaction‐assisted laser desorption/ionization mass spectrometry (NPILDI‐MS) for rapid, simple, direct and sensitive detection of microorganisms on the basis of our past and present reports, quoting examples of successful application of this technique. Finally, we address the future of the NPILDI‐MS technique and the tools needed to reach those visions. Copyright © 2012 John Wiley & Sons, Ltd.     

[2,6‐Bis(3,5‐di­methyl­pyrazol‐1‐yl­methyl‐κN2)­pyridine‐κN]bis­(thiocyanato‐N)copper(II)

The title compound, [Cu(NCS)₂(C₁₇H₂₁N₅)], displays a distorted square‐pyramidal coordination geometry, where the basal plane is defined by the tridentate ligand and by one of the thio­cyanate ions. The apical position is occupied by the other thio­cyanate ion.     

Liquid chromatography–tandem mass spectrometric assay for aliskiren,a novel renin inhibitor in micro‐volumes of human plasma: a pharmacokinetic application in healthy South Indian male subjects

This paper describes a simple, rapid and sensitive liquid chromatography/tandem mass spectrometry assay for the determination of aliskiren in human plasma using nevirapine as an internal standard. Analyte and the internal standard were extracted from 100 μL of human plasma via liquid–liquid extraction using tert‐butyl methyl ether. The chromatographic separation was achieved on a C₁₈ column using a mixture of acetonitrile and 0.1% formic acid (90:10, v/v) as the mobile phase at a flow rate of 0.9 mL/min. The calibration curve obtained was linear (r² ≥ 0.99) over the concentration range of 0.10–1013 ng/mL. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. A run time of 2.2 min for each sample made it possible to analyze a greater number of samples in a short time, thus increasing the productivity. The proposed method was found to be applicable to clinical studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Signatures of an extended rigidity percolation in the photo-degradation behavior and the composition dependence of photo-response of Ge-Te-In glasses

Time dependent photocurrent measurements have been undertaken on bulk Ge₁₅Te_85−xIn_x (1 ? x ? 11) series of glasses. It is found that samples with x < 3 do not exhibit any photo-degradation whereas a decrease in photo-conductivity under illumination is observed in samples with x ? 3. Further, the photosensitivity of Ge₁₅Te_85−xIn_x glasses is found to reveal specific signatures at compositions x = 3 and 7. The observed composition dependent photo-degradation behavior and photo-response of these glasses have been understood on the basis of an extended rigidity percolation and its influence on network related properties.     

纳米贵金属插入的粘土用于催化选择性加氢反应

 The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hectorite) were synthesised and their catalytic activity was evaluated for the selective hydrogenation of three different α,β-unsaturated aldehydes, namely, crotonaldehyde, cinnamaldehyde, and citral, in a gas phase microreactor. The metal nano-sol was prepared by the chemical reduction of its precursor by the micellar technique in the presence of cetyl trimethyl ammonium bromide (CTAB), and the micelle stabilized metal particles were intercalated in the clay mineral by ion exchange. TEM micrographs of the catalyst particles showed that the metal particles were in the nanometre range. The average diameters of the particles were 1–25 nm. The effects of temperature, metal loading, and hydrogen flow rate on the catalytic activity and selectivity for α,β- unsaturated alcohol were studied. The results were correlated with the structural properties of the catalysts. The products formed in each reaction over the different catalysts showed that the catalysts were very active for hydrogenation, and the selectivity for the desired product, namely, α,β-unsaturated alcohol, was good. The metal catalysts intercalated in montmorillonite showed better selectivity than that in hectorite because of its higher acidity. Increased selectivity for α,β-unsaturated alcohol was observed with increased flow rate of hydrogen.     

Stability of stochastic Leipholz column with stochastic loading

Summary The Leipholz column which is having the Young modulus and mass per unit length as stochastic processes and also the distributed tangential follower load behaving stochastically is considered. The non self-adjoint differential equation and boundary conditions are considered to have random field coefficients. The standard perturbation method is employed. The non self-adjoint operators are used within the regularity domain. Full covariance structure of the free vibration eigenvalues and critical loads is derived in terms of second order properties of input random fields characterizing the system parameter fluctuations. The mean value of critical load is calculated using the averaged problem and the corresponding eigenvalue statistics are sought. Through the frequency equation a transformation is done to yield load parameter statistics. A numerical study incorporating commonly observed correlation models is reported which illustrates the full potentials of the derived expressions.

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Stabilität eines Leipholz-Stabes mit stochastischen Eigenschaften und Belastungen

Übersicht Behandelt wird der Leipholz-Stab, dessen Elastizitätsmodul, Masseverteilung und tangential folgende Streckenlast stochastisch sind. Die nicht selbstadjungierte Differentialgleichung und die Randbedingungen werden als solche mit Zufallskoeffizienten betrachtet und die übliche Störungsmethode benutzt. Im Regularitätsbereich werden die nicht selbstadjungierten Operatoren benutzt. Hergeleitet wird die vollständige Kovarianz-Struktur der Eigenwerte der freien Schwingung und kritischen Lasten als Funktionen der Eigenschaften zweiter Ordnung der zufälligen Eingangsgrößen, die die Schwankungen der Systemparameter charakterisieren. Der Mittelwert der kritischen Last wird aus dem gemittelten Problem berechnet und die zugehörige Eigenwert-Statistik wird gesucht. Über die Frequenzgleichung wird eine Transformation vorgenommen, um die Statistik des Lastparameters zu erhalten. Eine numerische Studie illustriert die Leistungsfähigkeit der hergeleiteten Ausdrücke.

     

Tetrathiomolybdate assisted epoxide ring opening with masked thiolates and selenoates: multistep reactions in one pot

Tetrathiomolybdate provides an easy access to beta-hydroxy disulfides, beta-hydroxy sulfides, and selenides from epoxides in a tandem, multistep process in one pot. This strategy has been utilized effectively in the construction of thiabicylo[3.2.2]nonane derivative 24.     

35 GHz ENDOR characterization of the "very rapid" signal of xanthine oxidase reacted with 2-hydroxy-6-methylpurine (13C8): evidence against direct Mo-C8 interaction.

Xanthine oxidase is a molybdenum-containing enzyme that catalyzes the hydroxylation of xanthine and a wide variety of other aromatic heterocycles. In the course of the reaction with xanthine and substrates such as 2-hydroxy-6-methylpurine (HMP), the enzyme gives rise to a Mo(V) EPR signal, denoted "very rapid", that arises from an authentic catalytic intermediate. The two alternative catalytic mechanisms proposed for this enzyme differ critically in whether the distance between Mo and C8 of the purine nucleus in this intermediate is short enough to admit a direct bonding interaction. To examine this distance, we have performed 13C ENDOR measurements of the "very rapid" EPR signal generated by xanthine oxidase during reaction with 13C8-HMP. The resulting (13)C8 hyperfine tensor, A = [10.2(1), 7.0(1), 6.5(1)] MHz, is discussed in the framework of a detailed consideration of factors involved in extracting metrical parameters from an anisotropic hyperfine interaction composed of contributions from multiple sources, in particular, the effect of the local contributions from spin density on (13)C8. The analysis presented here gives a Mo...C distance whose value is expected to be ca. 2.7-2.9 A in the "very rapid" intermediates formed with both xanthine and HMP, consistent with plausible bond lengths for a Mo-O-C8 fragment where C8 is a trigonal-planar aromatic carbon. The difference from earlier conclusions is explained. The data thus do not support the existence of a direct Mo-C bond in the signal-giving species. This conclusion supports a mechanism that does not involve such an interaction and which begins with base-assisted nucleophilic attack of the Mo(VI)-OH group on the C-8 of substrate, with concomitant hydride transfer to the Mo=S group to give Mo(IV)-SH; the EPR-active "very rapid" species then forms by one-electron oxidation and deprotonation to yield the EPR-detectable Mo(V)OS(OR) species. We further discuss the complexities and limitations of the semiempirical method used to arrive at these conclusions.     

Efficient and versatile catalysis for β-alkylation of secondary alcohols through hydrogen auto transfer process with newly designed ruthenium(II) complexes containing ON donor aldazine ligands

A new series of ruthenium(II) carbonyl complexes, [RuCl(CO)(EPh₃)₂(L_1-2)] (1–4) (E = P or As; H₂L₁ = salicylaldazine, H₂L₂ = 2-hydroxynaphthaldazine), have been assembled from ruthenium(II) precursors [RuHCl(CO)(EPh₃)₃] and bidentate ON donor Schiff base ligands (H₂L_1-2). Both ligands and their new ruthenium(II) complexes have been characterized by elemental analyses, spectroscopic methods (UV, IR, NMR (¹H, ¹³C, ³¹P) as well as ESI mass spectrometry. The molecular structures of H₂L₁ and 1 have been confirmed by single crystal X-ray diffraction. Based on the above studies, an octahedral coordination geometry around the metal center has been proposed for 1–4. To investigate the catalytic effectiveness of 1–4, the complexes have been used as catalysts in β-alkylation of secondary alcohols with primary alcohols and synthesis of quinolines. The effect of solvent, time, base, catalyst loading, and substituent of the ligand moiety on the reaction was studied. Notably, 1 was a more efficient catalyst toward alkylation of a wide range of alcohols and quinolines synthesis. The reusability of the catalyst was checked and the results showed up to six catalytic runs without significant loss of activity.     

Spectral studies of methyl‐p‐hydroxy benzoate: An organic nonlinear optical crystalline material

The single crystals of Methyl‐p‐Hydroxy Benzoate (MHB) were grown by solution growth technique and characterized by X‐ray diffraction (single crystal), density, melting point, UV‐Vis, FT‐IR and FT‐Raman techniques. Electron Paramagnetic Resonance (EPR) spectra of Cu²⁺: MHB were recorded and the spin Hamiltonian parameters were evaluated. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)