Isolation and structure of a new alkaloid from rauwolfia serpentina benth

A new dihydroindole alkaloid sandwicolidine has been isolated from Rauwolfia serpentina and its structure elucidated through chemical and spectroscopic studies.     

Fabrication and characterization of polyvinyl chloride/poly(styrene-co-maleic anhydride) intercalated functional nanobifiller-based composite paper

The resin infiltration technique was used for impregnation of graphene oxide (GO) and graphene oxide-functional carbon nanotube (GO-ox-CNT) with polyvinyl chloride (PVC) and poly(styrene-co-maleic anhydride) (PSMA) blend. Two series of buckypapers were prepared with GO and GO-ox-CNT content. The morphology of PVC/PSMA/GO composite paper was porous, while PVC/PSMA/GO-ox-CNT revealed exclusive morphology with GO islands and intercalated ox-CNT networks covered with PVC/PSMA. T_max of PVC/PSMA/GO-ox-CNT 0.1 was 571°C, whereas PVC/PSMA/GO 0.1 had a lower value (559°C). T_g of PVC/PSMA/GO-ox-CNT 0.1 was also higher (290°C). Cone calorimetric results showed a decrease in PHRR from 499 (blend) to 186 kW/m² with 0.3 g GO-ox-CNT.     

New dammarane and ursane-type triterpenoids from the flower of Ixora coccinea Linn.

Two new esters of dammarane triterpenoids ixorene isovalerate (1), ixorene 3′,8′-dimethyloctanoate (2) and a new ursane-type triterpenoids Ixoroid acid (3) were isolated from the methanolic extract of flowers of Ixora coccinea Linn., along with the three known constituents. The structures of compounds 1 and 3 were elucidated on the basis of extensive 1D,2D NMR studies and mass spectrometry as 17β-dammara-12,20-diene-3β-isovelarate and 3β-hydroxy-18β-urs-12ene-29β-oic acid, respectively, whereas 2 was identified as 17β-dammara-12,20-diene-3β-3′,8′-dimethyloctanoate through ¹H NMR and mass spectral data. Compounds 1, 2, 4 and 5 were evaluated for their in vitro cytotoxic activity, which exhibited weak activity against the 3T3, PC3 and HeLa cell lines with the IC₅₀ value >30 μM. Antioxidant results of 1 – 5 revealed that only compound 5 showed antioxidant activity in DPPH radical scavenging inhibition with the IC₅₀ 1.31 × 10^? 6 ± 0.005 μm mL^? 1. Both activities are the first records of these isolated compounds from the flowers of Ixora coccinea Linn.     

On the Krylov subspace methods based on tensor format for positive definite Sylvester tensor equations

This paper deals with studying some of well‐known iterative methods in their tensor forms to solve a Sylvester tensor equation. More precisely, the tensor form of the Arnoldi process and full orthogonalization method are derived by using a product between two tensors. Then tensor forms of the conjugate gradient and nested conjugate gradient algorithms are also presented. Rough estimation of the required number of operations for the tensor form of the Arnoldi process is obtained, which reveals the advantage of handling the algorithms based on tensor format over their classical forms in general. Some numerical experiments are examined, which confirm the feasibility and applicability of the proposed algorithms in practice. Copyright © 2016 John Wiley & Sons, Ltd.     

The Dynamics of Quantum Correlations in Mixed Classical Environments

We present a comparative study of the dynamics of entanglement and quantum discord in a bipartite system in the presence of mixed classical noises. In particular, the joint effects of three different types of classical noises, namely, random telegraphic noise (RTN), Ornstein–Uhlenbeck noise (OU), and static noise, are studied by combining them in two different ways. In each case, one marginal system is coupled with random telegraphic noise, and the other marginal system is coupled with either OU or static noise. We make a comparison between the behaviors of both correlations in the two setups. In the weak coupling regime, the qualitative behavior of entanglement is unaffected by switching the coupling of only one marginal system from OU to static noise, and vice versa. However, the behavior of quantum discord strongly depends on whether it is coupled with OU or static noise. On the other hand, in the strong coupling regime, the static noise is more fatal to the survival of both correlations as compared to the other two noises.     

Ultrasound-mediated efficient synthesis of dihydrothiopyrano[2,3-<Emphasis Type="Italic">b</Emphasis>]indole-3-carbonitrile derivatives

An efficient one-pot synthesis of fused dihydrothiopyrano[2,3-b]indole-3-carbonitriles has been developed through ultrasound mediated reaction by simply combining malononitrile and various aldehydes with two indoline-2(3H)-thiones. The method has the advantages of high yields, short reaction time, good functional group tolerance and green reaction conditions.     

Convenient synthesis of 10H-indolo[3,2-b]quinolines and 6H-indolo[2,3-b]quinolines by sequential chemoselective Suzuki reaction followed by double C-N coupling

A convenient and regioselective synthesis of two series of indolo[2,3-b]quinolines, namely 10H-indolo[3,2-b]quinolines and 6H-indolo[2,3-b]quinolines, has been developed. The synthesis, proceeds in moderate to high yields, involving chemoselective palladium catalyzed Suzuki reaction of 2,3-dihaloquinolines with 2-bromophenylboronic acid, followed by a double Buchwald-Hartwig C-N coupling.     

Molecular Complexes of Crown Ethers: Part 7. Effect of Surfactant on the Charge-Transfer Complex between Dibenzo-18-Crown-6 and Tetracyanoethylene

The charge transfer complexes (CTC) of dibenzo-18-crown-6 (DB 1 8C6) andtetracyanoethylene (TCNE) were studied in the presence of the surfactant TritonX-100. It was found that the stability of the CTC increases with increasingconcentration of the donor, acceptor and the surfactant. This suggests that thecharge transfer complex is encapsulated in the micelle structure. Results of theeffect of time on the complex stability are also presented.