Strong Attraction of Caffeine to the Mercurous Dumbbell in the Salt [Hg2(Caf)2](ClO4)2(H2O)2

Colourless single crystals of the caffeine adduct of mercurous perchlorate dihydrate, [Hg₂(Caf)₂](ClO₄)₂(H₂O)₂, were grown from aqueous solutions of mercurous perchlorate and caffeine by isothermal evaporation at ambient temperature. The crystal structure (monoclinic, P2₁/n, Z = 4, a = 1628.0(2), b = 780.4(1), c = 2229.6(3) pm, β = 99.84(1)°, R₁(all data) = 0.0894) contains [trans‐Caf‐Hg‐Hg‐Caf]²⁺ cations with a Hg‐Hg distance of 250.88(6) pm, Hg‐N (bond) distances of 214.4(6) and 215.1(6) pm and Hg‐Hg‐N angles of 176.9(2) and 165.1(2)°, respectively. These cations are attached via weak Hg‐O contacts to dimers which are further arranged to leave large channels into which one crystal water molecule is included. The second water molecule and the two perchlorate anions are weakly attracted to one Hg atom.     

Chlorination reaction behavior of Zircaloy-4 hulls: experimental and theoretical approaches

Chlorination reaction behavior of Zircaloy-4 (Zry-4) cladding hulls was demonstrated by using a quartz reactor system. By reacting at 380 °C for 3 h, mass of the Zry-4 hulls decreased by 65.8 wt% with Cl₂ utilization of 87.1 mol%. Composition of collected product was analyzed and it was revealed that concentration of Zr was higher than 99.97 wt%. The purity of Zr in the experimental result was higher than expectation when considering Sn (1.31 wt%) and Fe (0.25 wt%) contents which can produce gaseous SnCl₄ and FeCl₃ at the experimental condition. Theoretical calculations were performed to clarify the high purity of Zr by using the HSC code. The simulation results revealed that formation of ZrCl₄ is more preferred than SnCl₄, FeCl₃, and CrCl₃. The preference of chloride formation was confirmed by the theoretical calculation, and it was suggested that the major constituents of Zry-4 might react with Cl₂ to produce chlorides in an order of ZrCl₄ > CrCl₃ > SnCl₄ > FeCl₃. It was also suggested that continuous removal of ZrCl₄ and sufficient supply of Zr source during the chlorination reaction might have contributed to the high purity of Zr.     

Preparation of a reference material “Creatinine in Human Urine”

Two batches of a reference material “Creatinine in Human Urine” have been prepared with creatinine concentrations at the physiological level, and used in interlaboratory comparisons in which up to 26 laboratories participated employing up to 4 independent methods. The 95% confidence intervals obtained for the certified creatinine concentrations are better than the “acceptable ranges” of commercially control samples available for clinical laboratories, the certified values being traceable to mean values of the commercial control samples. Thus, a suitable reference material has been prepared for the quality assurance of environmental and occupational health studies in which the concentration of a pollutant or its metabolites in human urine has to be related to the creatinine concentration.     

Fingerprints of Phalaenopsis Tissues in Growth and Spike Induction Periods—A Solid‐state 13C NMR Approach

Solid‐state Nuclear Magnetic Resonance (ss‐NMR) ¹³C single‐pulse excitation spectroscopy in combination with the magic‐angle spinning (MAS) technique was applied to a series of Phalaenopsis tissues, including the leaf, sheath, stem, and root, at different growth and spiking periods. Compared with{¹H}/¹³C cross‐polarization MAS spectra, the ¹³C single‐pulse excitation MAS spectra displayed very distinct spectral patterns, recognizable as fingerprints of the tissues studied. ¹Here, we demonstrate that solid‐state ¹³C single‐pulse excitation NMR spectroscopy provides a direct and robust analytical tool for studying the various tissues of Phalaenopsis in different growth and spiking induction periods.     

Photoinduced superoxide radical anion and singlet oxygen generation in the presence of novel selenadiazoloquinolones (an EPR Study)

Novel 7‐substituted 6‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐h]quinoline ( SeQ(1–6) ) and 8‐substituted 9‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐f ]quinoline derivatives ( SeQN(1–5) ) with R₇, R₈ = H, COOC₂H₅, COOCH₃, COOH, COCH₃ or CN were synthesized and their spectral characteristics were obtained by UV/Vis spectroscopy. Ultraviolet A photoexcitation of the selenadiazoloquinolones in dimethylsulfoxide or acetonitrile resulted in the formation of paramagnetic species coupled with molecular oxygen activation generating the superoxide radical anion or singlet oxygen, evidenced by electron paramagnetic resonance spectroscopy. The cytotoxic/photocytotoxic impact of selenadiazoloquinolones on murine and human cancer cell lines was demonstrated using the derivative SeQ5 (with R₇ = COCH₃).     

Tetrachlorosilane Catalyzed Dithioacetalization

Tetrachlorosilane was found to be a mild as well as selective catalyst for dithioacetalization of the carbonyl compounds.     

Anhydrous Deprotection of Dimethyl Acetals with Acetyl Chloride/ZnCl2

Dimethyl acetals are converted to the corresponding aldehyde in THF with acetyl chloride/zinc chloride in the presence of dimethyl sulfide     

Removal of acidic dyestuffs in aqueous solution by nanofiltration

Separation of acidic dyestuffs, including Acid red 4, Acid orange 10, and Acid red 27, from aqueous solution by nanofiltration (NF) was shown to be a feasible process to accomplish an effective removal over a broad operational range. For most experiments conducted in this study, dyestuff rejections of greater than 98% were achieved. The permeate flux for experiments conducted with various dyestuffs was increased with increasing operating pressure and solution temperature. The permeability was increased and the rejection of dyestuffs was slightly decreased with increasing cross-flow velocity of solution. The effect of solution pH on the rejection of dyestuff was elucidated by the electrostatic characteristics between the species of dyestuff and the membrane surface. Maximum permeability was obtained for experiments operated in aqueous solution of pH 5, which was close to the isoelectric point of the membrane.