Heterogeneous reaction of SO2 on TiO2 particles

The heterogeneous reaction of SO₂ on TiO₂ particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The influences of the oxygen concentration, relative humidity (RH), and ultraviolet (UV) light illumination (λ ≈ 365 nm) intensity on the reaction were investigated. The main product of the heterogeneous reaction of SO₂ on TiO₂ particles was sulfate with UV illumination and sulfite without it. The production of sulfate was promoted significantly with UV illumination or water, and there was a synergistic effect when both were present. In the dry system without UV, the heterogeneous reaction of SO₂ on TiO₂ particles was found to be second-order for SO₂ and the initial uptake coefficient, γ_BET, was determined to be 1.94 × 10^?6. With UV and RH = 40%, the reaction order was first-order and the initial uptake coefficient was 1.35 × 10^?5.     

Phosphorous,nitrogen, and molybdenum ternary co-doped TiO2: preparation and photocatalytic activities under visible light

P, N, and Mo ternary co-doped nano TiO₂ photocatalysts ((P, N, Mo)-TiO₂) were prepared by a single step sol–gel method, which show much enhanced photocatalytic activities over Mo-TiO₂, (P, N)-TiO₂, un-doped TiO₂ and Degussa P25 under visible light irradiation. The degradation rate of 0.72Mo–P-TiO₂ is as high as 65.3%, which is about 6.7 times of that of Degussa P25. Possible reasons for the improvement of photocatalytic activities were analyzed.     

Traveling wave magnetophoresis for high resolution chip based separations

A new mode of magnetophoresis is described that is capable of separating micron-sized superparamagnetic beads from complex mixtures with high sensitivity to their size and magnetic moment. This separation technique employs a translating periodic potential energy landscape to transport magnetic beads horizontally across a substrate. The potential energy landscape is created by superimposing an external, rotating magnetic field on top of the local fixed magnetic field distribution near a periodic arrangement of micro-magnets. At low driving frequencies of the external field rotation, the beads become locked into the potential energy landscape and move at the same velocity as the traveling magnetic field wave. At frequencies above a critical threshold, defined by the bead's hydrodynamic drag and magnetic moment, the motion of a specific population of magnetic beads becomes uncoupled from the potential energy landscape and its magnetophoretic mobility is dramatically reduced. By exploiting this frequency dependence, highly efficient separation of magnetic beads has been achieved, based on fractional differences in bead diameter and/or their specific attachment to two microorganisms, i.e., B. globigii and S. cerevisiae.     

Silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes giving approach to chalcones

A silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes is reported. The method, with a wide range of substrate tolerance and mild operational conditions, can produce various chalcone derivatives in moderate to high yields from easily available starting materials.     

A novel silica-based column packing for reversed-phase HPLC of basic compounds

Summary A novel bonded phase for reversed-phase HPLC was synthesized in two steps. Octylamine was first reacted with β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (β-ECTS) and then the intermediate product was coupled onto porous silica. The prepared packing was characterized by elemental analysis, solid-state¹³C NMR and Fourier transform infrared (FT-IR). Chromatographic evaluations were carried out by using a mixture of organic compounds including acidic, basic and neutral analytes and methanol-water as binary mobile phase. The results showed that the stationary phase has excellent chromatographic properties and is resistant to hydrolysis between pH=2≈8. It can be used efficiently for the separation of basic compounds.     

Pyridinic nitrogen enriched porous carbon derived from bimetal organic frameworks for high capacity zinc ion hybrid capacitors with remarkable rate capability

Aqueous zinc ion hybrid capacitors(ZIHCs)hold great potential for large-scale energy storage applications owing to their high safety and low cost,but suffer from low capacity and energy density.Herein,pyridinic nitrogen enriched porous carbon(nPC)was successfully synthesized via the growth,subsequent annealing and acid etching of bimetal organic frameworks for high capacity and safe ZIHCs with exceptional rate capability.Benefiting from the mesopores for easy ion diffusion,high electrical conductivity enabled by in-situ grown carbon nanotubes matrix and residual metal Co nanoparticles for fast electron transfer,sufficient micropores and high N content(8.9 at%)with dominated pyridinic N(54%)for enhanced zinc ion storage,the resulting nPC cathodes for ZIHCs achieved high capacities of 302 and137 m Ah g^-1 at 1 and 18 A g^-1,outperforming most reported carbon based cathodes.Theoretical results further disclosed that pyridinic N possessed larger binding energy of-4.99 eV to chemically coordinate with Zn2+than other N species.Moreover,quasi-solid-state ZIHCs with gelatin based gel electrolytes exhibited high energy density of 157.6 Wh kg^-1 at 0.69 kW kg^-1,high safety and mechanical flexibility to withstand mechanical deformation and drilling.This strategy of developing pyridinic nitrogen enriched porous carbon will pave a new avenue to construct safe ZIHCs with high energy densities.     

Viable but nonculturable cells used in biosensor fabrication for long-term storage stability

In this paper, we first reported the viable but nonculturable (VBNC) cells used for fabricating biosensor. The organic-inorganic hybrid material composed of silica and the grafting copolymer of poly(vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)) was used to immobilize microbial cells for biosensor fabrication. The VBNC cells were formed after the hybrid material dried, showing the cell walls were sacrificed. With the intracellular enzymes as core and the “sacrificed” cell walls as shell, the present VBNC cells maybe considered as a core/shell structure. The extracellular material worked as the scaffold for core/shell structure. The core/shell structure and the scaffold structure were demonstrated by single-cell level image analysis using confocal laser scanning microscopy (CLSM). The electrochemical method was adopted for further examining the enzyme activity of VBNC cells. The VBNC cells did not need nutrient treatment and other physicochemical factors for cell growth, which is a significant contribution for storing biosensor. A glucose-glutamic acid biosensor fabricated by the VBNC cells exhibited long-term storage stability for 100 days.     

Effects of the receptors bearing phenol group and copper(II) on the anion recognition and their analytical application

Two novel artificial receptors based on diamide and bearing phenol group and copper(II) have been synthesized. Their anion-binding properties are evaluated for F⁻, Cl⁻, Br⁻, I⁻, AcO⁻, H₂PO₄⁻ and OH⁻ by UV-vis and ¹H NMR titration experiments to further elucidate the impact of phenol group and copper(II) on the chemistry of anion-recognition. Results indicate that the interacted model of fluoride anion with receptor 1 is different from other anions and the ¹H NMR signals of receptor 2 occur changes after the addition of fluoride anion. This may be related with the small radius and strong electronegative property of fluoride. The receptors should have many chemical and analytical applications and the sensing principle should be widely applicable to the sensing of other receptors.     

A novel intramolecular reversible reaction between the hydroxyl group and isobutenylene chain in a cyclophane-type macrocycle

A novel Hg²⁺ ion induced reversible ring contraction was achieved employing the intramolecular reaction of isobutylene with an aromatic hydroxyl group of cyclophane; reversibility of the reaction was facilitated by excess addition of NaBH₄ which also resulted in complexation. The ring contraction and expansion was monitored by UV-VIS absorption, and by fluorescence and ¹H NMR spectra. Switchable fluorescence behavior (on—off—on) was observed when the ring-size was tuned from a 19-membered ring to an 18-membered and vice versa. This fine tuning has the potential to be applied in the construction of new supramolecular devices.     

Phenanthroline complexes bearing diamide-anion recognition sites

The synthesis and anion binding properties of new ruthenium(II) and cobalt(II) phenanthroline complexes, containing two amide subunits are described. Evidence for anion binding in dimethyl sulfoxide (DMSO) solution was obtained from u.v.–vis titration experiments. Results indicated that these receptors showed strong affinity for F⁻ and AcO⁻, and showed weak affinity for OH⁻ and H₂PO ₄ ⁻ , and showed no affinity for Cl⁻, Br⁻, I⁻. These receptors interacted with various anions examined through hydrogen-bond formation.