Generalized model for time periodic electroosmotic flows with overlapping electrical double layers

In this article, an analytical model is devised for analyzing time periodic electroosmotic flows through nanochannels within the continuum regime, without presuming the validity of the Boltzmann distribution of ionic charges. The charge density distributions are obtained from the conservation considerations of the individual ionic species and other thermochemical constraints and are subsequently utilized to derive the potential distribution within the electrical double layer (EDL). This, coupled with the Navier-Stokes equation, yields a closed-form expression of the time-dependent velocity field that is valid under overlapped EDL conditions. This expression is first validated in asymptotic limits of thin EDLs, for which closed form expressions have been benchmarked in the literature. Further analyses are carried out to bring out the influences of the frequency of the electrical field on the electroosmotic flow features in the presence of overlapped EDLs.     

Analytical screening of polyadipates and other plasticisers in poly(vinyl chloride) gasket seals and in fatty food by gas chromatography-mass spectrometry

Fourteen poly(vinyl chloride) (PVC) gasket seals and 15 samples of pesto, tomatoes sauces, olive oil and olives in oil were analysed for the additives and plasticisers. The systematic screening of the representative samples revealed that epoxidised soybean oil (ESBO) was the principal plasticiser in eight gaskets and the concentrations of the substance ranged from 15% to 42%. Diisodecyl phthalate (DIDP) as main plasticiser was revealed in three samples and the amount ranged from 37 to 41%. Polyadipate was added in four samples at 16-46%. The concentration of ESBO exceeded 60 mg kg(-1) in three food samples with extreme at 281.9 mg kg(-1) and average 61.3 mg kg(-1). Di-(2-ethylhexyl) phthalate (DEHP) was detected in six food samples and it ranged from 2.5 to 8.7 mg kg(-1). The concentration of DEHP exceeded SML (3 mg kg(-1)) in five cases. The concentration of total polyadipate (PA) was 16.3 mg kg(-1) in average. All eight positive food samples for total PA showed the concentrations below SML (30 mg kg(-1)), which are specified for the fraction of polyadipates lower than 1000 Da. The migration rate of polyadipate in the food ranged from 1 to 7%. At such low transfer rate the polyadipates could be promising plasticisers for PVC gasket seals used in food industry.     

Cannabinoids,Phenolics, Terpenes and Alkaloids of Cannabis

Cannabis sativa is one of the oldest medicinal plants in the world. It was introduced into western medicine during the early 19th century. It contains a complex mixture of secondary metabolites, including cannabinoids and non-cannabinoid-type constituents. More than 500 compounds have been reported from C. sativa, of which 125 cannabinoids have been isolated and/or identified as cannabinoids. Cannabinoids are C₂₁ terpeno-phenolic compounds specific to Cannabis. The non-cannabinoid constituents include: non-cannabinoid phenols, flavonoids, terpenes, alkaloids and others. This review discusses the chemistry of the cannabinoids and major non-cannabinoid constituents (terpenes, non-cannabinoid phenolics, and alkaloids) with special emphasis on their chemical structures, methods of isolation, and identification.     

Investigation of quark distributions in a family of pentaquarks using the Thomas-Fermi quark model

Using the Thomas-Fermi quark model,a collective,spherically symmetric density of states is created to represent a gas of interacting fermions with various degeneracies at zero temperature.Over a family of pentaquarks,uudcc,color interaction probabilities were obtained after averaging over all the possible configurations.Three different functions are developed for light,charm,and anti-charm quarks and are assumed to be linearly related by some proportionality constants.Interesting patterns of quark distributions are observed while analyzing the quark function consistency conditions for such constants.     

Analytical Quality by Design (AQbD)-oriented RP-UFLC method for quantification of lansoprazole with superior method robustness

A reversed-phase ultrafast liquid chromatography method was developed for quantification of lansoprazole in pharmaceutical dosage form using analytical quality by design approach. Systematic planning and experimentation using design of experiment approach were used for method development and optimization studies. A central composite design was used for optimizing the chromatography, by choosing organic phase proportion and flow rate as the critical method variables for evaluating their effect on critical analytical attributes like resolution, plate number, and tailing factor. The optimal chromatography was accomplished on a C-18 column (250?×?4.6?mm, 5?µm) using methanol:water (70:30, v/v) as mobile phase at a flow rate of 1.0?mL/min. Photo diode array (PDA) detection was performed at 284?nm. Caffeine was used as the internal standard. Method validation studies revealed that the calibration curve was linear over 1.0–300?µg/mL. The method was found accurate with average recovery between 98.99 and 102.87%. The percent relative standard deviation values obtained for precision were as per ICH guideline and within the acceptance limits (<2%). Results of system suitability indicated superior method robustness. In a nutshell, the method was found to be highly suitable for its applicability in the determination of lansoprazole in bulk and tablet dosage form.     

Applications of Monte-Carlo simulation and chemometric techniques for development of bioanalytical liquid chromatography method for estimation of rosuvastatin calcium

In the present work, we investigated the development of a bioanalytical HPLC method of rosuvastatin (RSV) calcium as per the Quality by Design (QbD)-based systematic chemometric tools. At first, the method objectives were framed and critical analytical attributes (CAAs) were chosen. Risk assessment and factor screening was performed using Hybrid Risk Matrix and Plackett–Burman design for identifying vital factors influencing the critical method parameters (CMPs). Monte-Carlo simulation analysis was conducted which confirmed excellent process robustness (Ppk >1.33) for the studied ranges of CMPs. Furthermore, systematic method development was carried out using custom experimental design, where mobile phase ratio, pH, and injection volume were taken as CMPs at three levels. The obtained trials were evaluated for peak area, retention time, theoretical plates, and peak tailing as CAAs. Mathematical response surface modeling was carried out and optimal chromatographic solution was identified using response optimizer plots. Method transfer was made to bioanalytical scale for estimation of the analyte in rat plasma samples. Extensive method validation was performed as per the ICH Q2 guideline, which indicated validation parameters within the acceptable limits. Overall, the studies construed successful development of QbD compliant HPLC method of rosuvastatin with potential utility bioanalytical testing.     

Microwave synthesis of mono- and bis-tetrazolato complexes via 1,3-dipolar cycloaddition of organonitriles with platinum(II)-bound azides

[2 + 3] Cycloaddition reactions of the diazidoplatinum(II) complexes cis-[Pt(N3)2(PPh3)2] 1 and cis-[Pt(N3)2(2,2'-bipy)] 4 with organonitriles NCR 2 give the bis(tetrazolato) complexes trans-[Pt(N4CR)2(PPh3)2] 3 [R = Me (3a), Et (3b), Pr (3c), Ph (3d), 4-ClC6H4 (3e)] and cis-[Pt(N4CR)2(2,2'-bipy)] 5 [R = Me (5a), Et (5b), Pr (5c), Ph (5d)]. The reaction of cis-[Pt(N3)2(PPh3)2] I with propionitrile also affords, apart from 3b, the unexpected mixed cyano-tetrazolato complex trans-[Pt(CN)(5-ethyltetrazolato)(PPh3)2] 3b' which is derived from the reaction of the bis(tetrazolato) 3b with propionitrile, with concomitant formation of 5-ethyl-1H-tetrazole, via a suggested unusual oxidative addition of the nitrile to PtII. All these reactions are greatly accelerated by microwave irradiation and this method also shows a higher selectivity in the case of the reaction of propionitrile with 1, leading only to the formation of 3b. All the complexes obtained were characterized by IR, 1H, 13C and 31P[1H] (for complexes 3) NMR spectroscopies, FAB-MS and elemental analyses. Complexes 3b', 3d, 3e and 5d were also characterized by X-ray structural analyses.     

Microwave‐Assisted Tandem Transformation on an Ionic‐Liquid Support: Efficient Synthesis of Pyrrolo/Pyridobenzimidazolones and Isoindolinone‐Fused Benzimidazoles

A tandem transformation that involves the formation of three bonds and two heterocyclic rings in a one‐pot fashion through amino‐alkylation of an ionic‐liquid‐immobilized diamine with keto acids followed by successive double intramolecular cyclizations to afford a tricyclic framework has been explored. This tandem cyclization has been utilized to develop a rapid and efficient method to synthesize various pyrrolo[1,2‐a]benzimidazolones and pyrido[1,2‐a]benzimidazolones on an ionic‐liquid support by using focused microwave irradiation. The application of this tandem cyclization was further extended to the aromatic keto acids to provide isoindolinone‐fused benzimidazoles, a structurally heterogeneous library with skeletal diversity. The outcome of the cascade reaction was confirmed by the X‐ray crystallographic study of the product directly attached to the ionic‐liquid support. Use of the ionic liquid as a soluble support facilitates purification by simple precipitation along with advantages like high loading capacity, homogeneous reaction conditions, and monitoring of the reaction progress by regular conventional spectroscopic methods, whereas application of microwave irradiation greatly accelerates the rate of the reactions.     

Thiourea dioxide (TUD): a robust organocatalyst for oxidation of sulfides to sulfoxides with TBHP under mild reaction conditions

Thiourea dioxide (TUD) has been reported for the first time as a highly efficient and selective organocatalyst for the oxidation of sulfides to sulfoxides in high to excellent yields by using tert-butylhydroperoxide as oxidant under mild reaction conditions.     

Anomalous mixing behaviour in rotationally actuated microfluidic devices

We analyse the characteristics of two-fluid mixing in T-shaped microchannels on rotating platforms (Lab-on-a-Compact-Disk framework). Three regimes of mixing were identified based on the distinct flow behaviour in each of these regimes. A diffusion-based mixing regime was obtained for low rotation speeds. A Coriolis force based mixing regime was observed for intermediate rotation speeds, which introduced some nontrivial aspects in the mixing behaviour, which was explained through scaling analysis. At very high rotational speeds, rapid mixing close to the junction was achieved by exploiting flow instabilities (instability based mixing). A good agreement between the theoretical calculations and the experimental observations was obtained.