Mg/K2S2O8‐promoted direct carboxylation of saturated hydrocarbons with CO

Saturated hydrocarbons react with carbon monoxide in the presence of magnesium powder and potassium peroxodisulfate in trifluoroacetic acid (TFA) to afford the corresponding carboxylic acids as major products and alkyl trifluoroacetates as minor products in high yields. The use of equimolar amounts of magnesium (5 mmol) and K₂S₂O₈(5 mmol) is best for this reaction. Cyclohexane is carboxylated most effectively at 80 °C for 30 h using 50 atm CO, 3 ml of TFA and 1 mmol of cyclohexane, giving 80% conversion (95% conversion yield) based on cyclohexane. The reactivity of various saturated hydrocarbons has been determined by competitive reactions of equimolar amounts of cyclohexane (5 mmol) and another hydrocarbon (5 mmol). The order of decreasing reactivity obtained is cycloheptane > cyclohexane > cyclopentane > n‐propane > methane. Copyright ­© 1999 John Wiley & Sons, Ltd.     

An extended class of minimax generalized Bayes estimators of regression coefficients

We derive minimax generalized Bayes estimators of regression coefficients in the general linear model with spherically symmetric errors under invariant quadratic loss for the case of unknown scale. The class of estimators generalizes the class considered in Maruyama and Strawderman [Y. Maruyama, W.E. Strawderman, A new class of generalized Bayes minimax ridge regression estimators, Ann. Statist., 33 (2005) 1753–1770] to include non-monotone shrinkage functions.     

Analysis on heat stress-induced hyperphosphorylation of stathmin at serine 37 in Jurkat cells by means of two-dimensional gel electrophoresis and tandem mass spectrometry

Two-dimensional gel electrophoresis (2-DE) and tandem mass spectrometry were successfully used for determination of a phosphorylation site of stathmin induced by heat stress to Jurkat cells of a human T lymphoblastic cell line. The cells were incubated for 30 min at 41 degrees C up to 45 degrees C in a serum free 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffered culture medium. The intracellular soluble proteins were separated by 2-DE, and some of the proteins increased their abundance by heat stress. Those proteins were identified to be calmodulin, protein kinase C substrate, thymosin beta-4 and F-actin capping protein beta-subunit by peptide mass fingerprinting (PMF) with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). On the contrary, protein phosphatase 2C gamma-isoform, nucleophosmin, translationally controlled tumor protein, Rho GDP-dissociation inhibitor-1, eukaryotic translation initiation factors 5A and 3A subunit 2, ubiquitin-like protein SMT 3B and chloride intracellular channel protein-1 were decreased their abundance. A protein spot of M(r) 18,000 and pI 5.9 was markedly increased at temperatures higher than 43 degrees C at which the cells were led to apoptosis. The spot was identified to be stathmin of a signal relay protein which has a function of sequestering microtubule. MALDI-quadrupole ion trap (QIT)-TOF-MS/MS and immunoblotting with a monoclonal antibody specific for a phosphorylation site of stathmin showed that the spot was a phosphorylated stathmin at serine 37 (Ser 37). The phosphorylation was suppressed by treatment of cells with olomoucine of an inhibitor specific for cyclin dependent kinase (Cdk-1). These results strongly suggest that heat stress activates Cdk-1 which phosphorylates Ser 37 on the stathmin molecule. The phosphorylation may cause the functional loss of stathmin for dynamic microtubule assembly and leads Jurkat cells to cell cycle arrest and apoptosis.     

Application of high‐resolution ESI and MALDI mass spectrometry to metabolite profiling of small interfering RNA duplex

We investigated the application of a high‐resolution Orbitrap mass spectrometer equipped with an electrospray ionization (ESI) source and a matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometer to the metabolite profiling of a model small interfering RNA (siRNA) duplex TSR#34 and compared their functions and capabilities. TSR#34 duplex was incubated in human serum in vitro, and the duplex and its metabolites were then purified by ion exchange chromatography in order to remove the biological matrices. The fraction containing the siRNA duplex and its metabolites was collected and desalted and then subjected to high‐performance liquid chromatography (HPLC) equipped with a reversed phase column. The siRNA and its metabolites were separated into single strands by elevated chromatographic temperature and analyzed using the ESI‐Orbitrap or the MALDI‐TOF mass spectrometer. Using this method, the 5' and/or 3' truncated metabolites of each strand were detected in the human serum samples. The ESI‐Orbitrap mass spectrometer enabled differentiation between two possible RNA‐based sequences, a monoisotopic molecular mass difference which was less than 2 Da, with an intrinsic mass resolving power. In‐source decay (ISD) analysis using a MALDI‐TOF mass spectrometer allowed the sequencing of the RNA metabolite with characteristic fragment ions, using 2,4‐dihydroxyacetophenone (2,4‐DHAP) as a matrix. The ESI‐Orbitrap mass spectrometer provided the highest mass accuracy and the benefit of on‐line coupling with HPLC for metabolite profiling. Meanwhile, the MALDI‐TOF mass spectrometer, in combination with 2,4‐DHAP, has the potential for the sequencing of RNA by ISD analysis. The combined use of these methods will be beneficial to characterize the metabolites of therapeutic siRNA compounds. Copyright © 2012 John Wiley & Sons, Ltd.     

Redetermination of bis{[(2‐hydroxy­phenyl­methyl)­bis(2‐pyridyl­methyl)­aminato]copper(II)} diperchlorate

The structure of the title compound, [Cu₂(C₁₉H₁₈N₃O)₂](ClO₄)₂, was reported with insufficient accuracy because of a twinning problem by Adams, Bailey, Campbell, Fenton & He [J. Chem. Soc. DaltonTrans. (1996), pp. 2233–2237]. The dinuclear phenolate‐bridged Cu^II complex has an inversion centre.     

Chloro­[N′,N′‐diethyl‐N,N‐bis(2‐pyri­dyl­methyl)­ethyl­enedi­amine‐κ4N]copper(II) perchlorate

The title mononuclear copper(II) complex, [CuCl(C₁₈H₂₆N₄)]ClO₄, shows a square‐pyramidal coordination with the diethyl­amino N atom at the apical position. Large anisotropies in the displacement parameters of the non‐H atoms of the ligand seem to be due to rotational disorder of the ClO₄^? anion.     

Strictly Transparent Wavelength Conversion Using Multi-Wavelength Signal Generation

We succeeded in strictly transparent wavelength conversion by means of channel selection from multi-wavelength signals generated by sinusoidal modulation of input signal. Modulation-format-independent and bit-rate-independent wavelength conversion is achieved with small power penalty.     

Vibrational amplitude profile of molecular vibrational modes for vibrational mode assignment

Ultrashort pulse lasers with 6- and 20-fs durations were utilized for phthalocyanine thin film sample to induce several vibrational modes and vibration amplitude spectra were determined by multi-wavelength measurement technique. From the spectra we could identify the electronic states, which couple to two vibrational modes with frequencies of 670 and 750 cm⁻¹. It was shown that the vibrational amplitude profile obtained by the method can be used for providing information for the assignment of the vibrational mode.     

Dependence of chiral recognition on the degree of substitution of cellulose benzoate

A series of cellulose benzoates with different degrees of substitution (DS) were prepared by aminolysis under homogeneous conditions. Using them as a stationary phase, the dependence of the chromatographic chiral recognition of cellulose benzoate (CB) on its DS was studied under normal phase conditions. For most enantiomeric pairs, chiral recognition decreased along with the decrease in DS. However, some enantiomeric pairs were resolved only by CBs carrying unsubstituted hydroxyl groups. Many of the compounds were quite strongly retained by cellulose benzoate with a DS of 2.8. A study of the retention behaviors of simple achiral compounds led us to the conclusion that the change in the retention behaviors by introducing free hydroxyl groups into tribenzoate is not caused by hydrogen bonding including the hydroxyl groups, but by a specific unidentified change.