Individually addressable recessed gold microelectrode arrays with monolayers of thio-cyclodextrin nanocavities

Four, individually addressable 30 microm diameter, e-beam deposited, gold microelectrodes recessed by 6 microm were suitably spaced on a single substrate to avoid diffusional overlap between each microelectrode. The single substrate device was functionalised with thiolated alpha-, beta-, and gamma-cyclodextrin nanocavities without spacer groups to ensure close proximity of the cavities to the electrode surface. The microelectrodes were assessed in two stages. The e-beam deposited micron sized electrodes were characterized using models for recessed and inlaid microdisk electrodes. Subsequently, each individually addressable, atomically flat, micro-patterned gold electrode with thiolated CD ensembles was treated as a nanoporous electrode assembly. Theoretical and experimental results were compared using cyclic voltammetry. Atomic force microscopy was also used to characterise the modified microelectrodes. Comparisons were made with thiolated CDs deposited on macroelectrodes. This is the first report of the behaviour of immobilized CD nanocavities ensembles on atomically flat gold microelectrodes.     

Second-sphere coordination in hexaamminecobalt(III) salt with organic sulphonate anion: Synthesis, characterisation and X-ray crystal structure of [Co(NH3)6](CH3SO3)3

Reaction of hexaamminecobalt(III) chloride with the silver salt of methanesulphonic acid in aqueous medium (1:3 molar ratio) forms hexaamminecobalt(III) methanesulphonate, [Co(NH₃)₆](CH₃SO₃)₃, in high yield. This cobalt(III) complex has been characterized by spectroscopic techniques (UV/visible, IR and NMR) and its solubility product determined. The X-ray crystal structure shows that the [Co(NH₃)₆]³⁺ cations interact at the second sphere by sharing edges with the anions, via N–H  O hydrogen bonds. The structure is related to that of [Co(NH₃)₆]Cl(CH₃SO₃)₂, but is modified to accommodate additional anions in place of Cl⁻.     

UVB-induced photodamage to phycobilisomes of Synechococcus sp. PCC 7942

The effect of UVB irradiation on the phycobilisomes (PBSs) of Synechococcus sp. PCC 7942 cells was studied. The sucrose density-gradient-isolated PBSs from in vivo UVB-treated (280–320 nm) cells showed a strong decrease in β-phycocyanin (βPC) and -phycocyanin (PC) polypeptides. In addition to a decrease in the linker polypeptides LCM 75 (linker connecting the core to the thylakoid membranes), LR 33 (linker in the rod structure), LRC 31.5 (linker connecting the rod to the core) and LRC 29. In vitro UVB treatment of gradient-isolated intact PBSs for 1 h had no effect on any of the constituent polypeptides, and only after 2 h was a degradation of LCM 75 and LR 33 and a decrease in βPC evident. Further investigation of phycobiliproteins (4 h of UVB irradiation) using polyclonal antibody directed against purified whole PBSs revealed that, in vivo, there was a gradual decline in the levels of LCM 75, LR 33, LRC 31.5, LRC 29, βPC and PC.     

Photocatalytic degradation of azo dyes using Zn-doped and undoped TiO2 nanoparticles

Undoped and Zn-doped TiO₂ nanoparticles were synthesized by the sol gel method. The dopant (Zn) was taken at 0.1, 0.2, 0.5, 0.7, and 1.0 mol%. The initial precursors were titanium tetraisopropoxide and zinc acetate. The samples were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and UV–vis diffuse reflectance. The photocatalytic activity of the prepared nanoparticles was studied by observing their role in degradation of two azo dyes, i.e., Eriochrome Black T and Methyl Red under UV–visible light. The results revealed that Zn-doped TiO₂ nanoparticles exhibited better degradation as compared to undoped TiO₂ nanoparticles. In this study, 0.7 mol% Zn-doped TiO₂ showed highest photocatalytic activity. Doping of Zn allowed better separation of electron–hole pairs which results in increased oxidation and reduction reactions.     

Volumetric and Acoustic Studies of Binary Liquid Mixtures of Dipropylene Glycol Dimethyl Ether with Methyl Acetate, Ethyl Acetate and n-Butyl Acetate in the Temperature Range T = (288.15, 293.15, 298.15, 303.15, and 308.15) K

Densities and ultrasonic speeds have been measured over the whole composition range for binary liquid mixtures of dipropylene glycol dimethyl ether, CH₃(OC₃H₆)₂OCH₃, with methyl acetate, ethyl acetate, and n-butyl acetate using an Anton Paar DSA 5000 M density and speed sound analyzer at T = (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure in order to evaluate the behavior of these binaries. From these data excess the molar volume, $ V_{m}^{\text{E}} $ , and deviation in isentropic compressibility, ?κ _S , have been calculated. These excess properties have been fitted with the Redlich–Kister type polynomial equation to get their coefficients and standard deviations which provide a base for discussing the forces operating in solutions.     

Dynamic and Equilibrium Studies on Adsorption of Cu(II) Ions onto Biopolymeric Cross-Linked Pectin and Alginate Beads

Binary biopolymeric beads of alginate and pectin were prepared and characterized by FTIR spectra. On to the surfaces of the prepared beads were performed static and dynamic adsorption studies of Cu(II) ions at fixed pH and ionic strength of the aqueous metal ion solutions. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various adsorption parameters were calculated. The influence of various experimental parameters such as effect of time, pH, temperature, solid to liquid ratio, and the presence of salts were investigated on the adsorption of copper ions.     

Flame stabilization in high pressure LOx/GH2 and GCH4 combustion

Planar laser induced fluorescence (PLIF) of OH is used to examine flame stabilization in high pressure cryogenic flames formed by injecting a central jet of low speed liquid oxygen surrounded by a high speed gaseous stream of hydrogen or methane. In the LO_x/GH₂ experiments injection conditions are transcritical as the chamber pressure is above critical but the temperature is below critical . In the LO_x/GCH₄ experiments the chamber pressure and LO_x injection temperature are below critical , . Hydrogen or methane are injected at room temperature LIF images delineate the flame edge in the injector nearfield. The two flames are stabilized in the vicinity of the liquid oxygen injector lip but the anchor point is found to lie closer to the lip in the LO_x/GH₂ case and its displacement from shot to shot is of a smaller amplitude than that corresponding to the LO_x/GCH₄ flame. Interpretation of these data is based on a previous analysis which indicates that stabilization is essentially controlled by a dimensionless group formed by comparing the lip thickness to the flame edge thickness Ψ = h_s/δ_f. It is found that Ψ slightly exceeds unity in the LO_x/GH₂ case essentially fulfilling the stability condition while Ψ < 1 in the LO_x/GCH₄ case. In this last situation the flame is thicker than the characteristic thickness h_s and it is therefore sensitive to the high speed methane stream. Anchoring is imperfect and the flame edge moves with the turbulent eddies shed from the lip. Global stabilization is achieved dynamically but the reactive layer is not well established and the large amplitude motion of the edge is a symptom of a possible lift-off. Theoretical estimates indicate that LO_x/GCH₄ flame stabilization requires a thicker lip size than the LO_x/GH₂ propellant couple.