Bench-Top Type In Vivo EPR Spectrometer for Estimating the Renal Reducing Ability of a Rat

A main electromagnet optimized for electron paramagnetic resonance (EPR) measurements of rats by using a surface loop resonator with a loop diameter of 10?mm was designed. The fabricated main electromagnet was ca. 420?mm in diameter, ca. 240?mm in width, and ca. 60?kg in weight. When a static magnetic field of 25?mT was generated at the center of the main electromagnet, its deviation in a sphere space with a diameter of 10?mm was <0.02?mT. In this condition, the temperature elevation on the surface of the magnet was negligible for the measurement time assumed for in vivo study. Using this magnet, a bench-top type in vivo EPR spectrometer could be obtained, which made it possible to perform EPR measurements for estimating the renal reducing ability of a rat.     

Fabrication of novel layer-by-layer assembly films composed of poly(lactic acid) and polylysine through cation-dipole interactions

Novel layer-by-layer (LbL) assembly films composed of poly( L-lysine) (PLL) and poly( D-lactic acid) (PDLA) were prepared by the alternate immersion of a gold substrate into an aqueous PLL solution and an acetonitrile solution of PDLA. The formation of the LbL assembly film was confirmed by quartz crystal microbalance (QCM) analysis, atomic force microscopy observation, and attenuated total reflection Fourier transform infrared spectroscopy measurement. The driving force responsible for the LbL assembly was determined by investigating the formation behavior of the LbL assembly under various conditions. The formation of the LbL assembly was not affected either by the stereochemistry of polylysine and poly(lactic acid) or by the addition of urea, which is known to inhibit hydrogen bonding interaction between polymers, into the aqueous PLL solution. The LbL assembly was also formed by the combination of PDLA and polycations other than polylysine, such as poly(diallyldimethylammonium chloride). On the other hand, the combination of PDLA and any polyanions such as poly(styrene sulfonate sodium salt) produced little corresponding LbL assembly. The increase in positive charge on the amino nitrogen atom of PLL enhanced the LbL assembly. These results suggest that the LbL assembly film composed of PLL and PDLA was fabricated by cation-dipole interactions between the positive charge on the amino nitrogen atom of PLL and the lone pairs of the carbonyl oxygen atom of PDLA.     

Ab initio study of small acetonitrile cluster anions

Ab initio electronic structure calculations have been performed for (CH(3)CN)(2) (-) and (CH(3)CN)(3) (-) cluster anions using a diffuse basis set. We found both the dipole-bound structures and internal structures, where in the former structure an excess electron is mainly distributed on the surface of the cluster while an excess electron is internally trapped in the latter configuration. The optimized structures found for cluster anions were compared to those for neutral clusters. Potential-energy surfaces were also plotted as a function of appropriate internal coordinates in order to understand the interconversions of the optimized structures of clusters. The relative stabilities of the optimized confirmers have been discussed on the basis of the characteristics of these potential surfaces, relative energies, and electron vertical detachment energies.     

Potential-modulated fluorescence spectroscopy of the membrane potential-sensitive dye di-4-ANEPPS at the 1,2-dichloroethane/water interface

The spectrofluorometric behavior of a membrane potential-sensitive dye, 1-(3-sulfonatopropyl)-4-[β-{2-(di-N-butylamino)-6-naphthyl}vinyl]pyridinium betaine (di-4-ANEPPS), at the polarized 1,2-dichloroethane/water interface was studied by means of potential-modulated fluorescence (PMF) spectroscopy. The results, combined with those from cyclic and alternating current voltammetry, clearly suggested that the dye adsorbed at the interface underwent a reorientation with increasing the interfacial potential, giving a well-developed PMF response as well as a voltammetric response. In addition to the PMF response, another PMF response was observed by addition of dilauroyl phosphatidylcholine (DLPC). This additional response was well explained in terms of a reorientation of di-4-ANEPPS at the interface, which would be induced by the potential-dependent desorption of DLPC from the interface. Thus, the present study supported the reorientation/solvatochromic mechanism for the membrane potential-sensitive dye rather than the electrochromic mechanism.     

Effect of interfacial proteins on osteoblast-like cell adhesion to hydroxyapatite nanocrystals

A quartz crystal microbalance with dissipation (QCM-D) technique was employed to detecting the protein adsorption and subsequent osteoblast-like cell adhesion to hydroxyapatite (HAp) nanocrystals. The interfacial phenomena with the preadsorption of three proteins (albumin (BSA), fibronectin (Fn), and collagen (Col)), the subsequent adsorption of fetal bovine serum (FBS), and the adhesion of the cells were investigated. The QCM-D measured the frequency shift (Δf) and dissipation energy shift (ΔD), and the viscoelastic properties of the adlayers were evaluated using ΔD-Δf plot and Voigt-based viscoelastic model. The Col adsorption significantly showed higher Δf, ΔD, elasticity, and viscosity values as compared to the BSA and Fn adsorption, and the subsequent FBS adsorption depended on the preadsorbed proteins. The ΔD-Δf plot of the cell adhesion also showed a different behavior depending on the surfaces, and the Fn- and Col-modified surfaces showed the rapid mass and ΔD changes by forming the viscous interfacial layers with cell adhesion, indicating that the processes were affected by the cellular reaction through the extracellular matrix (ECM) proteins. The confocal laser scanning microscope images of adherent cells showed a different morphology and pseudopod on the surfaces. The cells adhered to the surfaces modified with the Fn and Col had significantly uniaxially expanded shapes and fibrous pseudopods, and those modified with the BSA had a round shape. Therefore, the different cell-protein interactions would cause the arrangement of the ECM and the cytoskeleton changes at the interfaces, and these phenomena were successfully detected by the QCM-D and Voigt-based model.     

The Surface Analysis Working Group at the Consultative Committee for Amount of Substance,Metrology in Chemistry and Biology: A successful initiative by Martin Seah

Dr Martin Seah, NPL, was the initiator, founder, and first chairman of the Surface Analysis Working Group (SAWG) at the Consultative Committee for Amount of Substance, Metrology in Chemistry and Biology (CCQM) at the Bureau International des Poids et Mesures (BIPM), the international organization established by the Metre Convention. This tribute letter summarizes his achievements during his chairmanship and his long-running impact on the successful work of the group after his retirement.     

Flow injection analysis for traces of zinc with immobilized carbonic anhydrase

A small column packed with immobilized bovine carbonic anhydrase is used for determination of traces of zinc in aqueous solution, based on the measurement of recovered esterase activity of the metal-free apoenzyme after taking up zinc from the sample solution. Conditions for the removal of zinc from the immobilized enzyme and for activity measurement are established. A linear calibration graph is obtained between 1 × 10^?8 and 4 × 10^?7 g of zinc. Then the method is successfully applied to the determination of zinc in tea, sediment and spring water.     

Synthesis of 4,10-dihydro-4,10-dioxo-1H[1]benzothiopyrano[3,2-B]pyridine and 7-oxo-7,13-dihydro[1]benzothiopyrano[2,3-b]-1,5-benzodiazepine

3-Amino-4H-1-benzothiopyran-4-one (3-aminothiochromone) was easily prepared by reaction of 3-bromo-thiochromen-4-one with sodium azide in methanol-water. Condensation of 3-aminothiochromone with diethyl ethoxymethylenemalonate and with dimethyl acetylenedicarboxylate gave intermediates, which were thermally cyclized to give 4,10-dihydro-4,10-dioxo-1H[1]benzothiopyrano[3,2-b]pyridinecarboxylates. 3-Formyl-thiochromone was condensed with o-phenylenediamine to give 7-oxo-7,13-dihydro[1]benzothiopyrano[2,3-b]-1,5-benzodiazepine.     

Cationic ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-α-L-arabinopyranose and synthesis of L-arabinofuranan

1,4-Anhydro-2,3-di-O-benzyl-α-L -arabinopyranose (=1,5-anhydro-2,3-di-O-benzyl-β-L -arabinofuranose) (ABAP) was synthesized and underwent cationic ring-opening polymerization with several kinds of Lewis acids. All the polylmers prepared by Lewis acids as catalyst were found to consist of two different structural units, α-furanosidic and β-furanosidic units, and the structure of the polymers greatly depended on the polymerization conditions. Polymerization of ABAP with antimony pentachloride catalyst at 0°C for 42 h gave a polymer with the highest α content of 93%, and that at ?20°C for 3 h gave a polymer with the lowest (25%) α content. The other catalysts such as phosphorus pentafluoride, boron trifluoride etherate, niobium pentafluoride, and tantalum pentafluoride also afforded polymers with mixed structure of α-and β-furanosides. After debenzylation of poly(ABAP), a new polysaccharide, L -arabinofuranan was obtained.     

Formation of non-racemic E- and Z-olefins based on discrimination of enantiotopic carbonyl groups in α-diketones by a chiral phosphonate reagent

A chiral HWE reagent reacted with an alternative carbonyl group of meso-α-diketones of bicyclo[2.2.1] system to give non-racemic (Z)- and (E)-olefins, respectively.