High-performance supercapacitors based on an ionic liquid-derived nanofibrillated mesoporous carbon

This article reports the superior specific capacitance, energy, and power density of a nanofibrillated mesoporous carbon derived from an ionic liquid source (IFMC). It was concluded that high specific capacitance and good electrical conductivity were originated from contribution of nitrogen content of IFMC, also the interesting nanofibrillated structure. A specific capacitance of 235 F g^?1 at a high discharge current of 5 A g^?1 was estimated for IFMC-based electrode which is higher than the most reported capacitance for carbon materials. An excellent performance of the nanofibrillated mesoporous carbon along with proper concentration of nitrogen constituent in the carbonaceous framework is indicative for important effects of tuning the carbon nanostructure for energy storage applications.     

Application of a thiourea‐containing task‐specific ionic liquid for the solid‐phase extraction cleanup of lead ions from red lipstick,pine leaves,and water samples

Here, task‐specific ionic liquid solid‐phase extraction is proposed for the first time. In this approach, a thiourea‐functionalized ionic liquid is immobilized on the solid sorbent, multiwalled carbon nanotubes. These modified nanotubes packed into a solid‐phase extraction column are used for the selective extraction and preconcentration of ultra‐trace amounts of lead(II) from aqueous samples prior to electrothermal atomic absorption spectroscopy determination. The thiourea functional groups act as chelating agents for lead ions retaining them and so, give the selectivity to the sorbent. Elution of the retained ions can be performed using an acidic thiourea solution. The effects of experimental parameters including pH of the aqueous solution, type and amount of eluent, and the flow rates of sample and eluent solutions on the separation efficiency are investigated. The linear dependence of absorbance of lead on its concentration in the initial solution is in the range of 0.5–40.0 ng/mL with the detection limit of 0.13 ng/mL (3s_b/m, n = 10). The proposed method is applicable to the analysis of red lipstick, pine leaves, and water samples for their lead contents.     

LC-MS/MS method for the simultaneous quantification of artesunate and its metabolites dihydroartemisinin and dihydroartemisinin glucuronide in human plasma

Artesunate (AS), a hemisuccinate derivative of artemisinin, is readily soluble in water and can easily be used in formulations for parenteral treatment of severe malaria. AS is rapidly hydrolyzed to the active metabolite dihydroartemisinin (DHA) and primarily eliminated by biliary excretion after glucuronidation. To investigate systematically the AS metabolism and pharmacokinetics, a novel liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of AS and its metabolites DHA and DHA glucuronide (DHAG) in human plasma samples was developed. Compared to previous methods, our method includes for the first time the quantification of the glucuronide metabolite using a newly synthesized stable isotope-labeled analogue as internal standard. Sample preparation was performed with only 50 μL plasma by high-throughput solid-phase extraction in the 96-well plate format. Separation of the analytes was achieved on a Poroshell 120 EC-C₁₈ column (50*2.1 mm, 2.7 μm, Agilent Technologies, Waldbronn, Germany). The method was validated according to FDA guidelines. Calibration curves were linear over the entire range from 1 to 2,500 nM (0.4–961.1 ng/mL), 165 to 16,500 nM (46.9–4,691.8 ng/mL), and 4 to 10,000 nM (1.8–4,604.7 ng/mL) for AS, DHA, and DHAG, respectively. Intra- and interbatch accuracy, determined as a deviation between nominal and measured values, ranged from ?5.7 to 3.5 % and from 2.7 to 5.8 %, respectively. The assay variability ranged from 1.5 to 10.9 % for intra- and interbatch approaches. All analytes showed extraction recoveries above 85 %. The method was successfully applied to plasma samples from patients under AS treatment.

Numerical Methods for the Pricing of Swing Options: A Stochastic Control Approach

In the natural gas market, many derivative contracts have a large degree of flexibility. These are known as Swing or Take-Or-Pay options. They allow their owner to purchase gas daily, at a fixed price and according to a volume of their choice. Daily, monthly and/or annual constraints on the purchased volume are usually incorporated. Thus, the valuation of such contracts is related to a stochastic control problem, which we solve in this paper using new numerical methods. Firstly, we extend the Longstaff–Schwarz methodology (originally used for Bermuda options) to our case. Secondly, we propose two efficient parameterizations of the gas consumption, one is based on neural networks and the other on finite elements. It allows us to derive a local optimal consumption law using a stochastic gradient ascent. Numerical experiments illustrate the efficiency of these approaches. Furthermore, we show that the optimal purchase is of bang-bang type.      

Kinetics of the esterification of palmitic acid with isobutyl alcohol

Kinetics of the sulfuric acid catalyzed esterification of palmitic acid with isobutyl alcohol has been studied and reviewed critically. A theoretical rate equation is derived by the following reaction mechanism: (1) The reaction of sulfuric acid and isobutyl alcohol produces isobutyl sulfuric acid which acts as a catalyst; (2) Palmitic acid is protonated by the catalyst to form the reaction intermediate; and (3) The esterification proceeds reversibly. The experimental results are consistent with this rate equation.     

Antiviral phytochemicals identification from Azadirachta indica leaves against HCV NS3 protease: an in silico approach

Hepatitis C virus (HCV) is a major health problem across the world affecting the people of all age groups. It is the main cause of hepatitis and at chronic stage causes liver cirrhosis and hepatocellular carcinoma. Various therapeutics are made against HCV but still there is a need to find out potential therapeutics to combat the virus. The goal of this study is to identify the phytochemicals of Azadirachta indica leaves having antiviral activity against HCV NS3 protease through molecular docking and simulation approach. Results show that the compound 3-Deacetyl-3-cinnamoyl-azadirachtin possesses good binding properties with HCV NS3/4A protease. It can be concluded from this study that Deacetyl-3-cinnamoyl-azadirachtin may serve as a potential inhibitor against NS3/4A protease.     

Synthesis and antioxidant activity study of carbothioamide and their corresponding thiazole derivatives

A novel series of 5-(p-(prop-2-ynyloxy)phenyl)-3-aryl-4,5-dihydropyrazole-1-carbothioamides 2a-f and functionalized 2-(3-(aryl)-5-(4-(prop-2-ynyloxy)phenyl)-4,5-dihydropyrazol-1-yl)-4-(3-arylsydnone-4-yl)thiazoles 4a-l were synthesized. The newly synthesized compounds were elucidated by analytical and spectral analysis. From the single-crystal X-ray diffraction method, it was observed that 2d crystallizes in a monoclinic crystal system with P21/n space group. The compounds 2d crystallized with cell parameters a = 15.0614 (19) Å, b = 6.0805 (7) Å, c = 20.903 (7) Å, α = 114.136 (6)^o, β = 110.709 (14) ^o, γ = 96.553 (5) ^o, V = 1790.6 (4) ų, Z = 4. From the Hirshfeld surface computational method, the major intercontacts present in these molecules are H…H (31.6%), C…H (18.2%) and S…H (12.2%), respectively. The newly synthesized compounds were tested for their ability to bleach 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical using DPPH scavenging assay. Among the synthesized compounds carbothioamide compounds 2c (90.7%) and 2b (89.8%) exhibited good DPPH scavenging activity compared to the rest of the compounds. Most of the synthesized carbothioamide molecules ( 2a-f ) found to be potent compared to the thiazole derivatives ( 4a-l ).     

Pharmaceutical physical form characterisation with fast (>200 °C min<Superscript>−1</Superscript>) DSC heating rates

Differential scanning calorimetry (DSC) has many applications during preformulation screening of new drug candidates, but definitive assignment of peaks to specific events in the sample is difficult without supplementary data from other techniques. To some extent these problems can be overcome by running multiple experiments at different heating rates. Typically 2 and 20 °C min⁻¹ are indicated. However, modern instruments are capable of achieving much faster heating rates (up to 750 °C commercially); with this extended range comes a new capacity for investigating the physical form of materials. Here, the use of fast DSC heating rates for materials characterisation is explored, focussing on determination of melting temperatures, glass formation and polymorph screening.     

Computation of the Delta in Multidimensional Jump-Diffusion Setting with Applications to Stochastic Volatility Models

We study the robustness of options prices to model variation in a multidimensional jump-diffusion framework. In particular, we consider price dynamics in which small variations are modeled either by a Poisson random measure with infinite activity or by a Brownian motion. We consider both European and Exotic options and we study their deltas using two approaches: the Malliavin method and the Fourier method. We prove robustness of the deltas to model variation. We apply these results to the study of stochastic volatility models for the underlying and the corresponding options.     

Commuting Values of Generalized Derivations on Multilinear Polynomials

Let K be a commutative ring with unity, R a prime K-algebra of characteristic different from 2, U the right Utumi quotient ring of R, f(x ₁,…, x _n ) a noncentral multilinear polynomial over K, and G a nonzero generalized derivation of R. Denote f(R) the set of all evaluations of the polynomial f(x ₁,…, x _n ) in R. If [G(u)u, G(v)v] = 0, for any u, v ∈ f(R), we prove that there exists c ∈ U such that G(x) = cx, for all x ∈ R and one of the following holds: 1. f(x ₁,…, x _n )² is central valued on R;

2. R satisfies s ₄, the standard identity of degree 4.