Chemo-bio catalysis using carbon supports: application in H2-driven cofactor recycling

Heterogeneous biocatalytic hydrogenation is an attractive strategy for clean, enantioselective C X reduction. This approach relies on enzymes powered by H₂-driven NADH recycling. Commercially available carbon-supported metal (metal/C) catalysts are investigated here for direct H₂-driven NAD⁺ reduction. Selected metal/C catalysts are then used for H₂ oxidation with electrons transferred via the conductive carbon support material to an adsorbed enzyme for NAD⁺ reduction. These chemo-bio catalysts show improved activity and selectivity for generating bioactive NADH under ambient reaction conditions compared to metal/C catalysts. The metal/C catalysts and carbon support materials (all activated carbon or carbon black) are characterised to probe which properties potentially influence catalyst activity. The optimised chemo-bio catalysts are then used to supply NADH to an alcohol dehydrogenase for enantioselective (>99% ee) ketone reductions, leading to high cofactor turnover numbers and Pd and NAD⁺ reductase activities of 441 h⁻¹ and 2347 h⁻¹, respectively. This method demonstrates a new way of combining chemo- and biocatalysis on carbon supports, highlighted here for selective hydrogenation reactions.

Heterogeneous chemo-bio catalytic hydrogenation is an attractive strategy for clean, enantioselective C X reduction.     

Irradiance fluctuations of partially coherent super Lorentz Gaussian beams

By using the semi-analytic approach introduced earlier, we formulate and subsequently evaluate the irradiance fluctuations of partially coherent super Lorentz Gaussian beams for orders of 10 and 11. Within the range of examined source and propagation conditions, our calculations show that there will be less fluctuations at short propagation distances as the Lorentzian property is increased. But the reverse will be applicable, if the longer propagation distances are considered. The use of focusing will cause reductions, particularly for beams with increased Lorentzian property.     

An electrochemical chiral sensor based on electrochemically modified electrode for the enantioselective discrimination of D-/L-tryptophan

Journal of Solid State Electrochemistry - Chirality is a universal characteristic of natural systems and discrimination of enantiomers of a chiral molecule plays a major role particularly in...     

Laser array beam propagation through liver tissue

Laser array beam propagating through mouse liver tissue is investigated. The turbulence power spectrum of the liver tissue is employed in the extended Huygens–Fresnel method to obtain an optical intensity profile and beam broadening at the observation point in biological liver tissue. Variations of the beam profile and the beam broadening are simulated based on the number of beamlets, source size, wavelength and the ring radius of the array. A biological tissue, illuminated by the laser array beam, exhibits different beam profiles and beam spot radius variations when the number of beamlets, source size, wavelength and the ring radius of the laser array beam are varied. Examining these variations observed in the propagated optical beam and comparing them with the test cases, abnormalities such as cancer and tumor in a biological liver tissue can be diagnosed.     

Thermodynamic and transport properties of (1,2-ethanediol + 1-nonanol) at temperatures from (298.15 to 313.15) K

Densities and kinematic viscosities have been measured for (1,2-ethanediol + 1-nonanol) over the temperature range from (298.15 to 313.15) K. The speeds of sound in those mixtures within the temperature range from (293.15 to 313.15) K have been measured as well. Using the measurement results, the molar volumes, isentropic compressibility coefficients, molar isentropic compressibilities, and the corresponding excess and deviation values (excess molar volumes, excess isentropic compressibility coefficients, excess molar isentropic compressibilities, differently defined deviations of the speed of sound, and dynamic viscosity deviations) were calculated. The excess Gibbs free energies estimated by the use of the UNIQUAC model are also reported. The excess molar volumes and Gibbs free energies are positive, whereas the compressibility excesses are s-shaped. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of variations of the structure of the system caused by the participation of two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding. The effect of temperature is discussed. The predictive abilities of the McAllister equation for viscosities of the mixtures under test have also been examined.     

Effect of indium incorporation on the optical properties of spray pyrolyzed Cd0.22Zn0.78S thin films

In this study, effect of indium incorporation on the optical properties is investigated for the spray pyrolyzed onto glass substrates at 275°C substrate temperature undoped and indium doped Cd_0.22Zn_0.78S thin films. The average optical transmittance of all the films was over 77% in the wavelength range between 450 and 800 nm. The optical band gap energies of the thin films have been investigated by the measurement of the optical absorbance as a function of wavelength. The optical absorption studies reveal that the transitions are direct band gaps of 3.02 and 3.05 eV for undoped and doped indium Cd_0.22Zn_0.78S thin films, respectively. The Urbach tail parameter and optical constants such as refractive index, extinction coefficient, and dielectric constants were calculated for these films. The dispersion parameters such as single-oscillator energy and dispersive energy were discussed in terms oft he single-oscillator Wemple—DiDomenico model.     

Evaluation of a tungsten coil atomization-laser-induced fluorescence detection approach for trace elemental analysis

The analytical utility of a tungsten (W)-coil atomization-laser-induced fluorescence (LIF) approach has been evaluated for trace level measurements of elemental chromium (Cr), arsenic (As), selenium (Se), antimony (Sb), lead (Pb), tin (Sn), copper (Cu), thallium (Tl), indium (In), cadmium (Cd), zinc (Zn) and mercury (Hg). Measurements of As, Cr, In, Se, Sb, Pb, Tl, and Sn were performed by laser-induced fluorescence using a single dye laser operating near 460 nm whose output was converted by frequency doubling and stimulated Raman scattering to wavelengths ranging from 196 to 286 nm for atomic excitation. Absolute limits of detection (LODs) of 1, 0.3, 0.3, 0.2, 1, 6, 1, 0.2 and 0.8 pg and concentration LODs of 100, 30, 30, 20, 100, 600, 100, 20, and 80 pg/mL were achieved for As, Se, Sb, Sn, In, Cu, Cr, Pb and Tl, respectively. Determinations of Hg, Pb, Zn and Cd were performed using two-color excitation approaches and resulted in absolute LODs of 2, 30, 5 and 0.6 pg, respectively, and concentration LODs of 200, 3000, 500 and 60 pg/mL, respectively. The sensitivities achieved by the W-coil LIF approaches compare well with those reported by W-coil atomic absorption spectrometry, graphite furnace atomic absorption spectrometry, and graphite furnace electrothermal atomization-LIF approaches. The accuracy of the approach was verified through the analysis of a multielement reference solution containing Sb, Pb and Tl which each had certified performance acceptance limits of 19.6-20.4 μg/mL. The determined concentrations were 20.05 ± 2.60, 20.70 ± 2.27 and 20.60 ± 2.46 μg/mL, for Sb, Pb and Tl, respectively. The results demonstrate that W-coil LIF provides good analytical performance for trace analyses due to its high sensitivity, linearity, and capability to measure multiple elements using a single tunable laser and suggest that the development of portable W-coil LIF instrumentation using compact, solid-state lasers is feasible.     

Ilwensisaponins A,B, C,and D: Triterpene Saponins from Scrophularia ilwensis

From the aerial parts of Scrophularia ilwensis, four new triterpene saponins, ilwensisaponins A–D ( 1 – 4 ) were isolated. The structures of the compounds were elucidated using chemical and spectral data as 13β, 28-epoxy-3-β-{{[β-D -glucopyranosyl-(1→2)]-[α-L -rhamnopyranosyl-(1→4)-β-D -glucopyranosyl-(1→3)]-β-D -fucopyranosyl}-oxy} olean-11-en-23-ol ( 1 ), 3-β-{{[β-D -glucopyranosyl-(1→2)]-[α-L -rhamnopyranosyl-(1→4)-β-D -glucopyranosyl-(1→3)]-β-D -fucopyranosyl}oxy}olena-11, 13(18)-diene-23, 28-diol ( 2 ), 3-β-{{[β-D -glucopyranosyl-(1→2)]-[α-L -rhamnopyranosyl-(1→4)-β-D glucopyranosyl-(1→3)]-β-D fucopyranosyl}oxy}-11α-methoxyolean- 12-ene-23, 28-diol (3) , and 3-β-{{[β-D -glucopyransoyl-(1→2)]-[α-L -rhamnopyranosyl-(1→4)-β-D -glucopyranosyl-(1→3)]-β-D -fucopyranosyl}oxy}olean-12-ene-11α,23,28-triol (4) .