Characterization of a solid state battery based on polyblend of (PVP+PVA+KBrO3) electrolyte

A potassium ion conducting polyblend electrolyte based on polyvinyl pyrrolidone (PVP) + polyvinyl alcohol (PVA) complexed with KBrO₃ was prepared using solution-cast technique. The electrical conductivity and transference number measurements were performed to characterize the polyblend electrolyte for battery applications. These measurements have shown that the electrolyte is a mixed (ionic + electronic) conductor, the charge transport being mainly ionic (t_ion=0.97). Using the electrolyte, electrochemical cells with configurations K / (PVP+PVA+KBrO₃)/(I₂), K / (PVP+PVA+KBrO₃)/(I₂+C) and K/(PVP+PVA+KBrO₃) / (I₂+C+electrolyte) were fabricated and their discharge characteristics studied. The cell with configuration K / (PVP+PVA+KBrO₃) / (I₂+C+electrolyte) exhibited better discharge characteristics than the other configurations. The other cell parameters like open circuit voltage (OCV), short circuit current (SCC) etc. were evaluated and are reported. Paper presented at the 2nd International Conference of Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Computing Influential Nodes Using the Nearest Neighborhood Trust Value and PageRank in Complex Networks

Computing influential nodes gets a lot of attention from many researchers for information spreading in complex networks. It has vast applications, such as viral marketing, social leader creation, rumor control, and opinion monitoring. The information-spreading ability of influential nodes is greater compared with other nodes in the network. Several researchers proposed centrality measures to compute the influential nodes in a complex network, such as degree, betweenness, closeness, semi-local centralities, and PageRank. These centrality methods are defined based on the local and/or global information of nodes in the network. However, due to their high time complexity, centrality measures based on the global information of nodes have become unsuitable for large-scale networks. Very few centrality measures exist that are based on the attributes between nodes and the structure of the network. We propose the nearest neighborhood trust PageRank (NTPR) based on the structural attributes of neighbors and nearest neighbors of nodes. We define the measure based on the degree ratio, the similarity between nodes, the trust values of neighbors, and the nearest neighbors. We computed the influential nodes in various real-world networks using the proposed centrality method. We found the maximum influence by using influential nodes with SIR and independent cascade methods. We also compare the maximum influence of our centrality measure with the existing basic centrality measures.     

Structure Activity Relationship Studies around DB18, a Potent and Selective Inhibitor of CLK Kinases

Three series of our lead CLK1 inhibitor DB18 have been designed, synthetized and tested against CLKs and DYRK1A kinases. Their cytotoxicity was subsequently measured on seven representative cancer cell lines. Guided by docking experiments, we focused on the less constrained part of the scaffold, and showed that drastically different substituents can be tolerated here. This work ended with the discovery of another promising derivative 12g, with IC₅₀ = 0.004 µM in the inhibition of HsCLK1 and IC₅₀ = 3.94 µM for the inhibition of HsDYRK1A. The SAR results are discussed in the light of extensive molecular modeling analyses. Finally, a kinome scan (463 human kinases) confirmed the outstanding selectivity of our lead compound DB18, suggesting that this scaffold is of prominent interest for selective CLK inhibitors. Altogether, these results pave the way for the development of inhibitors with novel selectivities in this family of kinases.     

Microwave- and Ultrasound-Assisted Extraction of Cannabinoids and Terpenes from Cannabis Using Response Surface Methodology

Limited studies have explored different extraction techniques that improve cannabis extraction with scale-up potential. Ultrasound-assisted and microwave-assisted extraction were evaluated to maximize the yield and concentration of cannabinoids and terpenes. A central composite rotatable design was used to optimize independent factors (sample-to-solvent ratio, extraction time, extraction temperature, and duty cycle). The optimal conditions for ultrasound- and microwave-assisted extraction were the sample-to-solvent ratios of 1:15 and 1:14.4, respectively, for 30 min at 60 °C. Ultrasound-assisted extraction yielded 14.4% and 14.2% more oil and terpenes, respectively, compared with microwave-assisted extracts. Ultrasound-assisted extraction increased cannabinoid concentration from 13.2–39.2%. Considering reference ground samples, tetrahydrocannabinolic acid increased from 17.9 (g 100 g dry matter⁻¹) to 28.5 and 20 with extraction efficiencies of 159.2% and 111.4% for ultrasound-assisted and microwave-assisted extraction, respectively. Principal component analyses indicate that the first two principal components accounted for 96.6% of the total variance (PC1 = 93.2% and PC2 = 3.4%) for ultrasound-assisted extraction and 92.4% of the total variance (PC1 = 85.4% and PC2 = 7%) for microwave-assisted extraction. Sample-to-solvent ratios significantly (p < 0.05) influenced the secondary metabolite profiles and yields for ultrasound-assisted extracts, but not microwave-assisted extracts.     

Cold Ethanol Extraction of Cannabinoids and Terpenes from Cannabis Using Response Surface Methodology: Optimization and Comparative Study

Efficient cannabis biomass extraction can increase yield while reducing costs and minimizing waste. Cold ethanol extraction was evaluated to maximize yield and concentrations of cannabinoids and terpenes at different temperatures. Central composite rotatable design was used to optimize two independent factors: sample-to-solvent ratio (1:2.9 to 1:17.1) and extraction time (5.7 min–34.1 min). With response surface methodology, predicted optimal conditions at different extraction temperatures were a cannabis-to-ethanol ratio of 1:15 and a 10 min extraction time. With these conditions, yields (g 100 g dry matter⁻¹) were 18.2, 19.7, and 18.5 for −20 °C, −40 °C and room temperature, respectively. Compared to the reference ground sample, tetrahydrocannabinolic acid changed from 17.9 (g 100 g dry matter⁻¹) to 15, 17.5, and 18.3 with an extraction efficiency of 83.6%, 97.7%, 102.1% for −20 °C, −40 °C, and room temperature, respectively. Terpene content decreased by 54.1% and 32.2% for extraction at −20 °C and room temperature, respectively, compared to extraction at −40 °C. Principal component analysis showed that principal component 1 and principal component 2 account for 88% and 7.31% of total variance, respectively, although no significant differences in cold ethanol extraction at different temperatures were observed.     

Stereoselective formal synthesis of aspergillide A

The stereoselective formal synthesis of aspergillide A (1), a cytotoxic 14-membered macrolide, is disclosed. The key intermediate, a trisubstituted tetrahydropyran core is prepared by SmI₂-induced intramolecular reductive cyclization as well as by using sequential α-aminooxylation, Horner-Wadsworth-Emmons olefination, and followed by Oxa-Michael cyclization. Other notable transformations in the synthesis include the use of Jacobsen’s hydrolytic kinetic resolution, esterification, ring-closing metathesis (RCM), and cross-metathesis (CM) reactions.     

Cellulose-SO3H: an efficient and biodegradable solid acid for the synthesis of quinazolin-4(1H)-ones

The condensation of 2-aminobenzamide with aldehydes or ketones has been achieved using cellulosesulfonic acid under mild reaction conditions to furnish 2,3-dihydroquinazolin-4(1H)-ones in good yields with a high selectivity. The use of biodegradable solid acid catalyst, cellulosesulfonic acid makes this method quite simple, more convenient, and practical. This catalyst was also found to be very active for the synthesis of hydroxyalkylquinazolin-4-ones from cyclic enol ethers.     

Molecular adducts between a few phenolic donors and pi-acceptors in solid-state

Electron donor-acceptor molecular complexes of a few phenolic donors with some quinonoid and tetracyanoethylene acceptors have been prepared by two different methods, i.e., by simple grinding of the respective component pair in the solid-state and in solution. Both the methods yielded identical dark colored 1:1 stoichiometric complexes. Spectral studies revealed that the complexes are ionic in nature. The g values obtained in ESR spectral studies for all these molecular adducts vary between 2.000 and 2.022, confirming the free radical nature of the adducts. The electronic absorption spectral studies proved that the donor-acceptor complexes formed initially, exhibit new electronic transitions at longer wavelengths, are less stable and disassociate readily into ionic type of adducts. The absorption maximum at longer wavelengths, i.e. >or=550 nm, are assigned to the charge transfer complexes, while the new transition at around 410 +/- 5 nm is attributed to the anion radical of the adducts. The ease of complexation not only depends on the ionization potential and electron affinities of the phenolic donors and the acceptors but is also structure sensitive. Complexation is confirmed by the shift in IR absorption of the phenolic hydroxyl group and the carbonyl group of quinone acceptors and the cyano group of tetracyanoethylene. Proton magnetic resonance studies indicate an interaction between the phenolic donors and acceptors on basis of the altered chemical shifts. Further, IR and NMR studies show that the stability of the adducts is governed not only by the charge transfer interaction but also by hydrogen bonding.     

Asymmetric aldol reactions in poly(ethylene glycol) catalyzed by l-proline

A rapid l-proline catalyzed direct aldol reaction between various aldehydes and acetone was achieved using PEG as the solvent with comparable enantioselectivities and yields to those obtained in other solvents. Recycling the catalyst and solvent (PEG) was possible 10 times without loss of activity.     

A novel intramolecular Ugi 3CC for the synthesis of N-alkyl-3-oxo-2-aryl-1,2,3,4-tetrahydropyrazino[1,2-a]indole-1-carboxamides

An intramolecular Ugi reaction of 2-(2-formyl-1H-indol-1-yl)acetic acid with aryl amines and isocyanides has been developed to produce a novel class of N-alkyl-3-oxo-2-aryl-1,2,3,4-tetrahydropyrazino[1,2-a]indole-1-carboxamides in good yields. This is the first report on intramolecular Ugi three component reaction of 2-(2-formyl-1H-indol-1-yl)acetic acid, aryl amine, and isonitrile.