Efficient and Sensitive Method for Quantitative Determination and Validation of Umbelliferone, Carvone and Myristicin in Anethum graveolens and Carum carvi Seed

An efficient HPTLC method for the analysis of umbelliferone, carvone and myristicin in Anethum graveolens and Carum carvi seed was developed. The method employed HPTLC plates precoated with silica gel 60 F₂₅₄ as the stationary phase. Methanol extracts of seeds from three different sources were used. The calibration plot for umbelliferone, carvone and myristicin were linear with the correlation coefficient of 0.997 ± 0.016, 0.999 ± 0.009 and 0.999 ± 0.013, respectively, which were indicative of good linear dependence of peak area on concentration. The method permits reliable quantification of umbelliferone, carvone and myristicin and showed good resolution and separation. The method was validated as per ICH guidelines. To study the accuracy of the method, recovery studies were performed by the method of standard addition at three different levels and the average percentage recovery was found to be 99.05% for umbelliferone, 100.28% for carvone and 99.8% for myristicin. The proposed HPTLC method for quantitative monitoring of umbelliferone, carvone and myristicin in A. graveolens and C. carvi seed can be used for routine quality testing of these extracts.     

The present and future of e-waste plastics recycling

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Controlled Release of an Antihypertensive Drug through Interpenetrating Polymer Network Hydrogel Tablets of Tamarind Seed Polysaccharide and Sodium Alginate

The application of interpenetrating polymer network (IPN) hydrogel tablets of tamarind seed polysaccharide and sodium alginate for controlled release of a water-soluble antihypertensive drug, propranolol HCl (PPL), was investigated. The IPN tablets loaded with PPL or PPL–resin complex (resinate) were prepared by a wet granulation/covalent cross-linking method. Fourier Transform Infrared Spectroscopic confirmed the cross-linking reaction and IPN formation, while X-ray Diffraction and Scanning Electron Microscopy studies confirmed the amorphous dispersion of the drug within the IPN tablets. The plain drug PPL showed complete release within 1 h, while drug release from the resinate was prolonged for 2.5 h and the IPN matrices showed drug release up to 24 h. The drug release rate from the IPN matrices was affected by polymer concentration and cross-linking time; the higher the cross-linking time, the slower was the drug release. The drug release mechanism was found to be of a non-Fickian type.     

Every transformation is disjoint from almost every non-classical exchange

A natural generalization of interval exchange maps are linear involutions, first introduced by Danthony and Nogueira (Ann Sci École Norm Sup (4) 26(6):645–664, 1993). Recurrent train tracks with a single switch which are called non-classical interval exchanges (Gadre in Ergod Theory Dyn Syst 32(06):1930–1971, 2012), form a subclass of linear involutions without flips. They are analogs of classical interval exchanges, and are first return maps for non-orientable measured foliations associated to quadratic differentials on Riemann surfaces. We show that every transformation is disjoint from almost every irreducible non-classical interval exchange. In the “Appendix”, we prove that for almost every pair of quadratic differentials with respect to the Masur–Veech measure, the vertical flows are disjoint.     

Computational study on the conformational preferences in nateglinide

Ab initio and semi‐empirical calculations were performed on the monomers, dimers and tetramers of the antidiabetic drug nateglinide to understand the conformational preferences and to explore their possible relation with polymorphism. The reported crystal structure of bis(nateglinide) hydronium chloride shows one asymmetric unit consisting of four different conformations of the drug nateglinide. The Becke, three‐parameter, Lee–Yang–Parr /6‐31+G(d,p) optimizations indicate that these conformers are energetically quite comparable and the differences disappear in gas phase. Our analysis shows that Φ (phi) torsion angle of this phenylalanine derivative is responsible for the observed differences in stability among the nateglinide conformations. Four different polymorphs of nateglinide (B, H, S and X2) were reported but the structural differences are not available. This quantum chemical study on the dimers of nateglinide helps in proposing the structures of polymorphs. As per the quantum chemical analysis, the dimer N‐44 is the structure of the stable polymorph, whereas, the dimers N‐AA, N‐CC and N‐AC are almost isoenergetic, thus proposed to be the structures of metastable state. The dimerization and tetramerization energies are estimated to be about ?9.0 and ?38.67 kcal/mol, respectively. The extra stability in tetrameric state compared with the dimeric form is attributed to additional hydrophobic and van der Waals interactions. Copyright © 2011 John Wiley & Sons, Ltd.     

Ruthenium‐Catalyzed Cascade CH Functionalization of Phenylacetophenones

Three orthogonal cascade C? H functionalization processes are described, based on ruthenium‐catalyzed C? H alkenylation. 1‐Indanones, indeno indenes, and indeno furanones were accessed through cascade pathways by using arylacetophenones as substrates under conditions of catalytic [{Ru(p‐cymene)Cl₂}₂] and stoichiometric Cu(OAc)₂. Each transformation uses C? H functionalization methods to form C? C bonds sequentially, with the indeno furanone synthesis featuring a C? O bond formation as the terminating step. This work demonstrates the power of ruthenium‐catalyzed alkenylation as a platform reaction to develop more complex transformations, with multiple C? H functionalization steps taking place in a single operation to access novel carbocyclic structures.     

Bandwidth enhancement of transformation optics-based cloak with reduced parameters

In this paper, dispersive cloak design with broad bandwidth and minimal scattering cross section is proposed by appropriately selecting a radial permeability for each shell in a discretized reduced cloak. The dispersive medium is constructed by artificially varying the inner radius of the cloak with frequency, and this variation results into unique material properties at every frequency. The variation of inner radius of the cloak with frequency is artificial since the actual physical dimension of inner radius remains invariant. The relation between bandwidth and geometrical parameters of cloak is obtained by ensuring that transformation media must satisfy the condition that group velocity must remain less than the speed of light along every direction for a finite frequency range. The proposed cloak provides \(8.9\,\%\) bandwidth with respect to the center frequency for \(50\,\%\) reduction in total scattering cross section, and at the design frequency, the minimum scattering cross section obtained is \(0.266\). The proposed dispersive cloak design is verified by numerical full-wave simulations results which also confirm good cloaking performance.     

Molecular Intercalation and Electronic Two Dimensionality in Layered Hybrid Perovskites

In layered hybrid perovskites, such as (BA)₂PbI₄ (BA=C₄H₉NH₃), electrons and holes are considered to be confined in atomically thin two dimensional (2D) Pb–I inorganic layers. These inorganic layers are electronically isolated from each other in the third dimension by the insulating organic layers. Herein we report our experimental findings that suggest the presence of electronic interaction between the inorganic layers in some parts of the single crystals. The extent of this interaction is reversibly tuned by intercalation of organic and inorganic molecules in the layered perovskite single crystals. Consequently, optical absorption and emission properties switch reversibly with intercalation. Furthermore, increasing the distance between inorganic layers by increasing the length of the organic spacer cations systematically decreases these electronic interactions. This finding that the parts of the layered hybrid perovskites are not strictly electronically 2D is critical for understanding the electronic, optical, and optoelectronic properties of these technologically important materials.     

Surface modification study of low energy electron beam irradiated polycarbonate film

The effect of low energy electron beam irradiation on polycarbonate (PC) film has been studied here. The PC film of thickness 20 μm was exposed by 10 keV electron beam with 100 nA/cm² current density. The irradiated film was characterized by mean of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and residual gas analyzer (RGA). Formation of unsaturated bonds and partial graphitization of the surface layer are measured by XPS. Results of the AFM imaging shows electron implantation induce changes in surface morphology of the polymer film. The residual gas analyzer (RGA) spectrum of PC is recorded in situ during irradiation. The results show the change in cross-linking density of the polymer at the top surface.     

Application of Particle Image Velocimetry and Reference Image Topography to jet shock cells using the hydraulic analogy

This paper examines the shock cell structure, vorticity and velocity field at the exit of an underexpanded jet nozzle using a hydraulic analogy and the Reference Image Topography technique. Understanding the flow in this region is important for the mitigation of screech, an aeroacoustic problem harmful to aircraft structures. Experiments are conducted on a water table, allowing detailed quantitative investigation of this important flow regime at a greatly reduced expense. Conventional Particle Image Velocimetry is employed to determine the velocity and vorticity fields of the nozzle exit region. Applying Reference Image Topography, the wavy water surface is reconstructed and when combined with the hydraulic analogy, provides a pressure map of the region. With this approach subtraction of surfaces is used to highlight the unsteady regions of the flow, which is not as convenient or quantitative with conventional Schlieren techniques. This allows a detailed analysis of the shock cell structures and their interaction with flow instabilities in the shear layer that are the underlying cause of jet screech.