A Rapid High-Performance Thin-Layer Chromatographic Method to Estimate Quercetin in Benincasa hispida (Thunb.) Cogn. Fruit Pulp

JPC – Journal of Planar Chromatography – Modern TLC - Ayurvedic medicines show great promise due to their holistic approach in the treatment of diseases. However, proper standardization...     

Polymer‐anchored mononuclear and binuclear CuII Schiff‐base complexes: Impact of heterogenization on liquid phase catalytic oxidation of a series of alkenes

Liquid phase catalytic oxidation of a number of alkenes, for example, cyclohexene, cis‐cyclooctene, styrene, 1‐methyl cyclohexene and 1‐hexene, was performed using polymer‐anchored copper (II) complexes PS‐[Cu (sal‐sch)Cl] ( 5 ), PS‐[Cu (sal‐tch)Cl] ( 6 ), PS‐[CH₂{Cu (sal‐sch)Cl}₂] ( 7 ) and PS‐[CH₂{Cu (sal‐tch)Cl}₂] ( 8 ). Neat complexes [Cu (sal‐sch)Cl] ( 1 ), [Cu (sal‐tch)Cl] ( 2 ), [CH₂{Cu (sal‐sch)Cl}₂] ( 3 ) and [CH₂{Cu (sal‐tch)Cl}₂] ( 4 ) were isolated by reacting CuCl₂·2H₂O with [Hsal‐sch] ( I ), [Hsal‐tch] ( II ), [H₂bissal‐sch] ( III ) and [H₂bissal‐tch] ( IV ), respectively, in refluxing methanol. Complexes 1–4 have been covalently anchored in Merrifield resin through the amine nitrogen of the semicarbazide or thiosemicarbazide moiety. A number of analytical, spectroscopic and thermal techniques, such as CHNS analysis, Fourier transform‐infrared, UV–Vis, PMR, ¹³C‐NMR, electron paramagnetic resonance, scanning electron microscopy, energy‐dispersive X‐ray analysis, thermogravimetric analysis, atomic force microscopy, atomic absorption spectroscopy, and electrospray ionization‐mass spectrometry, were used to analyze and establish the molecular structure of the ligands ( I )–( IV ) and complexes ( 1 )–( 8 ) in solid state as well as in solution state. Grafted complexes 5 – 8 were employed as active catalysts for the oxidation of a series of alkenes in the presence of hydrogen peroxide. Copper hydroperoxo species ([Cu^III (sal‐sch)‐O‐O‐H]), which is believed to be the active intermediate, generated during the catalytic oxidation of alkenes, are identified. It was found that supported catalysts are very economical, green and efficient in contrast to their neat complexes as well as most of the recently reported heterogeneous catalysts.     

Hollow‐Core Magnetic Colloidal Nanocrystal Clusters with Ligand‐Exchanged Surface Modification as Delivery Vehicles for Targeted and Stimuli‐Responsive Drug Release

The fabrication of hierarchical magnetic nanomaterials with well‐defined structure, high magnetic response, excellent colloidal stability, and biocompatibility is highly sought after for drug‐delivery systems. Herein, a new kind of hollow‐core magnetic colloidal nanocrystal cluster (HMCNC) with porous shell and tunable hollow chamber is synthesized by a one‐pot solvothermal process. Its novelty lies in the “tunability” of the hollow chamber and of the pore structure within the shell through controlled feeding of sodium citrate and water, respectively. Furthermore, by using the ligand‐exchange method, folate‐modified poly(acrylic acid) was immobilized on the surface of HMCNCs to create folate‐targeted HMCNCs (folate‐HMCNCs), which endowed them with excellent colloidal stability, pH sensitivity, and, more importantly, folate receptor‐targeting ability. These assemblages exhibited excellent colloidal stability in plasma solution. Doxorubicin (DOX), as a model anticancer agent, was loaded within the hollow core of these folate‐HMCNCs (folate‐HMCNCs‐DOX), and drug‐release experiments proved that the folate‐HMCNCs‐DOX demonstrated pH‐dependent release behavior. The folate‐HMCNCs‐DOX assemblages also exhibited higher potent cytotoxicity to HeLa cells than free doxorubicin. Moreover, folate‐HMCNCs‐DOX showed rapid cell uptake apart from the enhanced cytotoxicity to HeLa cells. Experimental results confirmed that the synthesized folate‐HMCNCs are smart nanovehicles as a result of their improved folate receptor‐targeting abilities and also because of their combined pH‐ and magnetic‐stimuli response for applications in drug delivery.     

A loop-by-loop defect rectification procedure for optimal synthesis of Stephenson III path generators

This paper presents a formulation of constraints for the synthesis of Stephenson III mechanism and a loop-by-loop defect-rectification procedure. The procedure divides the Stephenson III mechanism into two loops, namely, Loop I, i.e., four-bar, and Loop II, i.e., five-bar mechanisms. Then, the defects are identified using the established methodology to formulate the defect-specific constraints in the simplified form. Based on the constraints, an optimization problem is formulated to synthesize a Stephenson III mechanism for path generation. A well-established meta-heuristic algorithm is used to solve the constrained optimization problem. For demonstrating the effectiveness of the formulated constraints, two numerical examples are considered, in which Stephenson III path generator mechanisms are synthesized. It is found that the mechanisms synthesized using the proposed procedure are defect-free when constraints are imposed, which is verified using the stick-diagram.

     

Validated Method for the Simultaneous Determination of Lisinopril,Pravastatin, Atorvastatin and Rosuvastatin in API,Formulations and Human Serum by RP‐HPLC

Lisinopril is found to be useful in hypertension and statins as cholesterol lowering drug. Present work was designed for the simultaneous determination of lisinopril in presence of pravastatin, atorvastatin, and rosuvastatin using RP‐HPLC method. A Purospher star C18 (5 μm, 25×0.46 cm) column was used with mobile phase consisting of acetonitrile:water (60:40 V/V, pH 3.0) with flow rate of 1.0 mL·min^?1 and the quantitative evaluation was performed at 225 nm. The retention time of lisinopril was 2.0 min and for pravastatin, rosuvastatin and atorvastatin was found to be 3.1, 4.5 and 8.3 min respectively. Suitability of this method for the quantitative determination of the drugs was proved by validation in accordance with the requirements laid down by International Conference on Harmonization (ICH) guidelines. Application of the suggested procedures were successfully applied to the determination of these compounds in active pharmaceutical ingredient and in pharmaceutical preparations, with high percentage of recovery, good accuracy and precision.     

Pseudo-differential Operators,Cubature and Equidistribution on the 3D ball: An Approach Based on Orthonormal Basis Systems

In this paper, the distribution of points on a unit ball in ?³ is investigated. The ansatz is motivated by an approach for point grids on the unit sphere by Cui and Freeden. A formula for a generalized discrepancy is developed, which is then used to check the uniformity of point grids on a ball. The generalized discrepancy originates from an error bound for a quadrature (cubature) rule on the ball with uniform weights. In particular, we discuss the integration of functions from particular Sobolev spaces based on known orthonormal systems on the ball. This includes the introduction of a concept of pseudo-differential operators on the ball. Finally, different point grids are constructed on the ball and are compared by the discrepancy. Furthermore, numerical and graphical comparisons of the grids are presented.     

Carbon Nanosheets Synthesis in a Gliding Arc Reactor: On the Reaction Routes and Process Parameters

Non-thermal plasma is a promising technology for high purity nanomaterial synthesis in a fast, flexible and controllable process. Gliding arc discharge, as one of the most efficient non-thermal plasmas, has been widely used in gas treatment but rarely studied for the nanomaterial synthesis. In this study, a comparison study for carbon nanosheets synthesis including toluene dissociation and graphite exfoliation was investigated in a 2D gliding arc reactor at atmospheric pressure. The effects of gas flow rate, precursor concentration and power input on the structures of carbon nanosheets produced through the two synthesis routes were explored and compared. Amorphous carbon nanosheets were produced in both approaches with a few crystalline structures formation in the case of toluene dissociation. The thickness of carbon nanosheets synthesized from graphite exfoliation was less than 3 nm, which was thinner and more uniform than that from toluene dissociation. The flow rate of carrier gas has direct influence on the morphology of carbon nanomaterials in the case of toluene dissociation. Carbon spheres were also produced along with nanosheets when the flow rate decreased from 2 to 0.5 L/min. However, in the case of graphite exfoliation, only carbon nanosheets were observed regardless of the change in flow rate of the carrier gas. The generated chemical species and plasma gas temperatures were measured and estimated for the mechanism study, respectively.

     

Thermophysical and Spectroscopic Studies of Pure 1-Butyl-3-methylimidazolium Tetrafluoroborate and Its Aqueous Mixtures

Intermolecular interactions in the aqueous mixtures of the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), have been studied. The thermophysical properties: density ρ, speed of sound u, specific conductivity κ and refractive index n _D have been measured over the whole composition range at different temperatures (293.15–323.15 K) and are discussed. The results from thermophysical measurements are explained with the help of spectroscopy. In order to interpret the nature of molecular interactions occurring between [BMIM][BF₄] and water molecules, as well as to identify the moieties in which interactions are taking place, ¹H, ¹³C NMR and FT-IR spectra of the solutions have been studied. Excess molar volume V ^E, excess molar isentropic compressibility $ K_{S}^{\text{E}} $ , partial molar excess volume $ V_{i}^{\text{E}} $ , partial molar excess isentropic compressibility $ K_{S,i}^{\text{E}} $ , deviation in specific conductivity ?κ, and deviation in refractive index ?R have also been determined and analyzed to have a better understanding of the interactions taking place between the different components. Additionally, the excess ultrasonic speed u ^E and excess isentropic compressibility $ k_{S}^{\text{E}} $ , in terms of volume fractions, have been calculated and analyzed. It has been observed that temperature has a significant effect on the thermophysical properties of the studied system. Spectroscopic measurements confirm the disruption of ion-pair interactions of [BMIM][BF₄] and hydrogen-bonded network of water in the aqueous mixture of [BMIM][BF₄].     

Evaluation of radon induced lung cancer risk in occupants of the old and new dwellings of the Dera Ismail Khan City,Pakistan

In order to carry out indoor radon measurement in new and old buildings of the Dera Ismail Khan city, CR-39 based radon detectors were installed in bed rooms and sitting rooms/TV lounges in 25 (each) old and new houses and were exposed to indoor radon for 90 days. After processing, mean weighted average indoor radon concentrations in old and new houses were found to be 275 ± 33 and 86 ± 18 Bq m^?3 whereas mean annual effective doses expected to be received by the occupants were 6.86 ± 0.79 and 2.1 ± 0.43 mSv year^?1, respectively. From the measured weighted average indoor radon concentration, excess relative risk factor was calculated using the risk model of BEIR VI for the age group of 35 and 55 years. Average excess lung cancer risk was found to be 1.63 ± 0.19 and 1.35 ± 0.16 and 0.5 ± 0.10 and 0.4 ± 0.08 for old and new houses, respectively.