Ordinary Mode Instability in a Cairns Distributed Electron Plasma

Employing the linearized Vlasov-Maxwell equations, a generalized dispersion relation for the ordinary mode is derived by employing the Cairns distribution function. The instability of the mode and its threshold condition is investigated. It is found that the temperature anisotropy χ = T_∥/T_⊥ 1 required to excite the instability varies with density values whereas the growth rate is dependent on various parameters like non-thermality Λ, equilibrium number density n_0 and temperature anisotropy. It is found that with the increase in the values of any of the parameters Λ, n_0 and χ, the growth rate is enhanced and the k-domain is enlarged. The results are applicable for space plasma environments like solar wind.     

Novel N-aryl and N-heteroaryl sulfamide synthesis via palladium cross coupling

A novel and efficient synthesis of N-aryl and N-heteroaryl sulfamides via an intermolecular palladium-catalyzed coupling process has been developed. The reactions proceeded with good to excellent yields and were tolerant of a wide range of functional groups. [reaction: see text]     

Synthesis of new chiral 2,2'-bipyridine ligands and their application in copper-catalyzed asymmetric allylic oxidation and cyclopropanation

A series of modular bipyridine-type ligands 1 and 3-9 has been synthesized via a de novo construction of the pyridine nucleus. The chiral moieties of these ligands originate from the isoprenoid chiral pool, namely, beta-pinene (10 --> 1), 3-carene (14 --> 3 and 5), 2-carene (28 --> 4), alpha-pinene (43 --> 6-8), and dehydropregnenolone acetate (48 --> 9), respectively. Copper(I) complexes, derived from these ligands and (TfO)(2)Cu (1 mol %) upon an in situ reduction with phenylhydrazine, exhibit good enantioselectivity (up to 82% ee) and unusually high reaction rate (typicaly 30 min at room temperature) in allylic oxidation of cyclic olefins (52 --> 53). Copper-catalyzed cyclopropanation proceeded with < or =76% enantioselectivity and approximately 3:1 to 99:1 trans/cis-diastereoselectivity (54 --> 55 + 56). The level of the asymmetric induction is discussed in terms of the ligand architecture that controls the stereochemical environment of the coordinated metal.     

Heat capacity,electrical and thermal conductivity of silicene

We investigate the electronic heat capacity, electrical and thermal conductivity ofmonolayer planar and buckled silicon sheets (silicene) through tight binding approximationand Kubo-Greenwood formula. Applying and increasing dopant atoms to the system leads toopening a gap in the band structures and density of states that causes to decrease(increase) the heat capacity before (after) the Schottky anomaly. The electrical andelectronic thermal conductivity of doped silicene reduces with increasing impuritystrength.     

New Lewis-basic N-oxides as chiral organocatalysts in asymmetric allylation of aldehydes

Allylation of aromatic and heteroaromatic aldehydes 1a-k with allyltrichlorosilane 2 can be catalyzed by the new heterobidentate, terpene-derived bipyridine N-monoxides 4, 6a,b, and 8-11 (相似文献   

A chemiluminescence sensor for the determination of hydrogen peroxide

A chemiluminescence one-shot sensor for hydrogen peroxide is described. It is prepared by immobilization of cobalt chloride and sodium lauryl sulphate in hydroxyethyl cellulose matrix cast on a microscope cover glass. Luminol, sodium phosphate and the sample are mixed before use and applied on the membrane by a micropipette. The calibration graph is linear in the range 20-1600 μg/L, and the detection limit of the method (3σ) is 9 μg/L. A relative standard deviation of 4.5% was obtained for 100 μg/L H₂O₂ (n = 11). The sensor has been applied successfully to the determination of hydrogen peroxide in rainwater.     

Investigation of Olea ferruginea Roylebark extracts for potential in vitroantidiabetic and anticancer effects

This study was conducted to investigate the physicochemical, phytochemical, in vitro antidiabetic and anticancer potential of Olea ferruginea R bark. After extraction using Soxhlet, in vitro antidiabetic and cytotoxic activity on human hepatocellular carcinoma (HepG2) cells was assessed by nonenzymatic glycosylation of hemoglobin assay, alpha-amylase inhibition assay, glucose uptake by yeast cells, and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay, respectively, and gene expression via real-time polymerase chain reaction. Primary and secondary metabolites were present in the extractants; polyphenols (35.61 ± 0.03) and flavonoids (64.33 ± 0.35 ) in the chloroform; and polysaccharides in the ethanol (268.75 ± 0.34), and glycosaponins (78.01 ± 0.07) in the methanol. The chloroform extract exhibited maximum antidiabetic potential, showing inhibition of nonenzymatic glycosylation of hemoglobin (65%), and alpha-amylase inhibition (32%) with maximum percent glucose uptake by the ethanol extract (78%). Only the ethanol extract had dose-dependent cytotoxic potential against the HepG2 cells. After 24-h exposure to the ethanol-extract, the expression of protein kinase B (Akt) remained unchanged, while the expression of B-cell lymphoma 2 (BCL2) and BCL2 associated X (BAX) changed significantly. After 48-h exposure, the expression of Akt decreased significantly, while that of BCL2 and BAX increased significantly. Olea ferruginea R bark possessed in vitro antidiabetic potential and anticancer/cytotoxic effects, attributable to the decline in the prosurvival signals of the Akt signaling pathway.     

Urease-Dextran complexes with enhanced enzymatic activity and stability

In this study, the urease-dextran non-covalent complexes in various molar ratios were synthesized and compared to the free enzyme in terms of pH, temperature, thermal and storage stabilities. Especially, the complex with a molar ratio of n_U/n_DA = 40/1 showed highest thermal stability and had ca. 1.4-fold at 25°C and 2.5-fold at 80°C higher activity than the free enzyme. The complex showed a high catalytic activity in organic solvent. In addition, the thermal and storage stabilities of urease were improved greatly as dextran complex, which has advantages for usage in practice.     

Rocket (Eruca vesicaria (L.) Cav.) vs. Copper: The Dose Makes the Poison?

The effects of copper addition, from various adsorbents, on the accumulation ability and glucosinolate content of cultivated rocket were studied. Different adsorbents (zeolite NaX, egg shells, substrate, fly ash) were treated with copper(II) solution with an adsorption efficiency of 98.36, 96.67, 51.82 and 39.13%, respectively. The lowest copper content and the highest total glucosinolate content (44.37 μg/g DW and 4269.31 µg/g DW, respectively) were detected in the rocket grown in the substrate with the addition of a substrate spiked with copper(II) ions. Rocket grown in the fly ash-substrate mixture showed an increase in copper content (84.98 μg/g DW) and the lowest total glucosinolate content (2545.71 µg/g DW). On the other hand, when using the egg shells-substrate mixture, the rocket copper content increased (113.34 μg/g DW) along with the total GSLs content (3780.03 µg/g DW), indicating the influence of an adsorbent type in addition to the copper uptake. The highest copper content of 498.56 μg/g DW was detected in the rocket watered with copper(II) solution with a notable decrease in the glucosinolate content, i.e., 2699.29 µg/g DW. According to these results rocket can be considered as a copper accumulator plant.