Energy and Foliations on Riemann Surfaces

We define the energy of foliations on Riemann surfaces. We prove that meromorphic vector fields are critical points and we compute their energies using the Green’s function. We then generalize the results to principal circle bundles over Riemann surfaces.Mathematics Subject Classification (2000): 53C12, 53C15.     

Thermal study of PN thermoelectric couple by laser induced Seebeck EMF measurement

We propose in this paper an in-depth study of a method, both experimental and theoretical, for the determination of thermoelectric properties, in single, or multi-layered thermoelectric devices. We use a modulated laser beam as a heater in order to generate a thermally induced Seebeck EMF. The laser beam, line shaped, can be focused at any location along the sample surface, allowing spatially resolved measurements. Seebeck EMF measurements, associated with a versatile modeling method based on the thermal quadrupoles, allow determining sample Seebeck EMF profile. We contemplate to apply this technique to thermal and thermoelectric properties identification.     

Rapid One-Pot Synthesis of Alkane-α,ω-Diylbisphosphonic Acids from Dihalogenoalkanes Under Microwave Irradiation

A one-pot, two-step synthesis of alkylenebisphosphonic acids from dihalogenoalkanes was performed under microwave irradiation. The reaction is very rapid and convenient for the synthesis of small samples of alkylenebisphosphonic acids.     

Antimicrobial activity and phytochemical screening of Arbutus unedo L.

In this study, antimicrobial activities of water and methanol extract, and three phenolic fractions of the roots of Arbutus unedo L. were investigated. Poor antibacterial activity against both Staphylococcus aureus and Pseudomonas aeruginosa bacteria was shown with water and methanol extract. However moderate antibacterial activity was shown by water extract and phenolic fractions against Escherichia coli and S. aureus, respectively. The phytochemical screening of roots of A. unedo revealed the presence of quinones, anthraquinones reducteurs compounds, anthocyanins, tannins and flavonoids. Quantitative analysis showed that the roots were strongly dominated by anthocyanins compounds (3.65 mg g^?1) followed by total flavonoids (0.56 mg^?1) and flavones & flavonols (0.17 mg g^?1).     

Beyond the Polysulfide Shuttle and Lithium Dendrite Formation: Addressing the Sluggish Sulfur Redox Kinetics for Practical High‐Energy Li‐S Batteries

Electrolyte modulation simultaneously suppresses polysulfide the shuttle effect and lithium dendrite formation of lithium–sulfur (Li‐S) batteries. However, the sluggish S redox kinetics, especially under high S loading and lean electrolyte operation, has been ignored, which dramatically limits the cycle life and energy density of practical Li‐S pouch cells. Herein, we demonstrate that a rational combination of selenium doping, core–shell hollow host structure, and fluorinated ether electrolytes enables ultrastable Li stripping/plating and essentially no polysulfide shuttle as well as fast redox kinetics. Thus, high areal capacity (>4 mAh cm^?2) with excellent cycle stability and Coulombic efficiency were both demonstrated in Li metal anode and thick S cathode (4.5 mg cm^?2) with a low electrolyte/sulfur ratio (10 μL mg^?1). This research further demonstrates a durable Li‐Se/S pouch cell with high specific capacity, validating the potential practical applications.     

Chlorpromazine Electro‐oxidation at BDD Electrode Modified with nZVI Nanoparticles Impregnated NiAl LDH

Nanocomposite of nanoscale zero‐valent iron (nZVI) and layered double hydroxide (LDH) was used as modifier for boron‐doped diamond electrode in determination of anti‐psychotic drug chlorpromazine (CPZ). nZVI nanoparticles were prepared by liquid phase reduction of ferric chloride with sodium borohydride on the surface of NiAl LDH matrix owing to the strong exchange and confinement efficiency of LDH. The structure, binding and surface properties of the nZVI@LDH nanocomposite were monitored using powder X‐ray diffractometry, FT‐IR spectroscopy, scanning and transmission microscopy and BET techniques. The electrochemical properties of the modified electrode were investigated by CV and EIS, performed in a phosphate buffer containing ferro/ferricyanide as redox probe. The modified electrode exhibited excellent electrochemical performance compared with unmodified electrode. As regard potential application of the nanocomposite surface to the CPZ detection, square‐wave voltammetric signals showed a good linear correlation over CPZ concentrations in a broad range from 0.1 to 8.0 μM with low detection limit of 0.005 μM. Nevertheless, these results suggest that the proposed nanocomposite modifier surface provides exceptional synergy and significant enhancement effect to the voltammetric response of CPZ and thus could be applied as highly efficient and stable platform of sensors in clinical analysis.     

Cation Additive Enabled Rechargeable LiOH-Based Lithium–Oxygen Batteries

Lithium–oxygen (Li–O₂) batteries have attracted extensive research interest due to their high energy density. Other than Li₂O₂ (a typical discharge product in Li–O₂ batteries), LiOH has proved to be electrochemically active as an alternative product. Here we report a simple strategy to achieve a reversible LiOH-based Li–O₂ battery by using a cation additive, sodium ions, to the lithium electrolyte. Without redox mediators in the cell, LiOH is detected as the sole discharge product and it charges at a low charge potential of 3.4 V. A solution-based reaction route is proposed, showing that the competing solvation environment of the catalyst and Li⁺ leads to LiOH precipitation at the cathode. It is critical to tune the cell chemistry of Li–O₂ batteries by designing a simple system to promote LiOH formation/decomposition.     

Synthesis,Characterisation and In Vitro Anticancer Activity of Hexanuclear Thiolato‐Bridged Arene Ruthenium Metalla‐Prisms

Hexanuclear thiolato‐bridged arene ruthenium metalla‐prisms of the general formula [(p‐cymene)₆Ru₆(SR)₆(tpt)₂]⁶⁺ (R=CH₂Ph, CH₂C₆H₄‐p‐tBu, CH₂CH₂Ph; tpt=2,4,6‐tris(4‐pyridyl)‐1,3,5‐triazine), obtained from the dinuclear precursors [(p‐cymene)₂Ru₂(SR)₂Cl₂], AgCF₃SO₃ and tpt, have been isolated and fully characterised as triflate salts. The metalla‐prisms are highly cytotoxic against human ovarian cancer cells, especially towards the cisplatin‐resistant cell line A2780cisR (IC₅₀ <0.25 μM ).     

A new sorbent for europium nitrate extraction: phosphonic acid grafted on polystyrene resin

A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid–solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H₂SO₄ solution and the grafted resin could be regenerated and reused.     

Removal of uranium(VI) from acetate medium using Lewatit TP 260 resin

Removal of uranium(VI) ions from acetate medium in aqueous solution was investigated using Lewatit TP260 (weakly acidic, macroporous-type ion exchange resin with chelating aminomethylphosphonic functional groups) in batch system. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The moving boundary particle diffusion model only fits the initial metal adsorption on the resin. The rate constant for the uranium sorption by Lewatit TP260 was 0.441 min⁻¹ from the first order rate equation. The total sorption capacity was found to be 58.33 mg g⁻¹ under optimum experimental conditions. Thermodynamic parameters (ΔH = 61.74 kJ/mol; ΔS = 215.3 J/mol K; ΔG = −2.856 kJ/mol) showed the adsorption of an endothermic process and spontaneous nature, respectively.