Nanophotonic structures with optical surface modes for tunable spin current generation.

We propose a novel type of photonic-crystal (PC)-based nanostructures for efficient and tunable optically-induced spin current generation via the spin Seebeck and inverse spin Hall effects. It has been experimentally demonstrated that optical surface modes localized at the PC surface covered by ferromagnetic layer and materials with giant spin-orbit coupling (SOC) notably increase the efficiency of the optically-induced spin current generation, and provides its tunability by modifying the light wavelength or angle of incidence. Up to 100% of the incident light power can be transferred to heat within the SOC layer and, therefore, to the spin current. Importantly, the high efficiency becomes accessible even for ultra-thin SOC layers. Moreover, the surface patterning of the PC-based spintronic nanostructure allows for the local generation of spin currents at the pattern scales rather than the diameter of the laser beam.

Enhanced Magneto-Optic Properties in Sputtered Bi- Containing Ferrite Garnet Thin Films Fabricated Using Oxygen Plasma Treatment and Metal Oxide Protective Layers.

Magneto-optic (MO) imaging and sensing are at present the most developed practical applications of thin-film MO garnet materials. However, in order to improve sensitivity for a range of established and forward-looking applications, the technology and component-related advances are still necessary. These improvements are expected to originate from new material system development. We propose a set of technological modifications for the RF-magnetron sputtering deposition and crystallization annealing of magneto-optic bismuth-substituted iron-garnet films and investigate the improved material properties. Results show that standard crystallization annealing for the as-deposited ultrathin (sputtered 10 nm thick, amorphous phase) films resulted in more than a factor of two loss in the magneto-optical activity of the films in the visible spectral region, compared to the liquid-phase grown epitaxial films. Results also show that an additional 10 nm-thick metal-oxide (Bi2O3) protective layer above the amorphous film results in ~2.7 times increase in the magneto-optical quality of crystallized iron-garnet films. On the other hand, the effects of post-deposition oxygen (O2) plasma treatment on the magneto-optical (MO) properties of Bismuth substituted iron garnet thin film materials are investigated. Results show that in the visible part of the electromagnetic spectrum (at 532 nm), the O2 treated (up to 3 min) garnet films retain higher specific Faraday rotation and figures of merit compared to non-treated garnet films.

Quality analysis, miceller behavior, and environmental impact of some laundry detergents available in Bangladesh.

The cleansing efficiencies of laundry detergents depend on composition and variation of ingredients such as surfactants, phosphate, and co-builders. Among these ingredients, surfactants and phosphate are considered as hazardous materials. Knowledge on compositions and micellar behavior is very useful for understanding their cleansing efficiencies and environmental impact. With this view, composition, critical micelle concentration, and dissolved oxygen level in aqueous solution of some laundry detergents available in Bangladesh such as keya, Wheel Power White, Tibet, Surf Excel, and Chaka were determined. Surfactant and phosphate were found to be maximum in Surf Excel and Wheel Power White, respectively, while both of the ingredients were found to be minimum in Tibet. The critical micelle concentration decreased with increasing surfactant content. The amount of laundry detergents required for efficient cleansing was found to be minimum for Surf Excel and maximum for Chaka; however, cleansing cost was the highest for Surf Excel and the lowest for Tibet. The maximum amount of surfactants and phosphate was discharged by Surf Excel and Wheel Power White, respectively, while discharges of both of the ingredients were minimum for Tibet. The maximum decrease of dissolved oxygen level was caused by Surf Excel and the minimum by Tibet. Therefore, it can be concluded that Tibet is cost-effective and environment friendly, whereas Surf Excel and Wheel Power White are expensive and pose a threat to water environment.

Plasmon-mediated magneto-optical transparency.

Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.

Surprising production of a new urdamycin derivative by S. fradiae Delta urdQ/R.

A strain (S. fradiae Delta urdQ/R) with mutations in urdQ and urdR encoding a dTDP-hexose-3,4-dehydratase and a dTDP-hexose-4-ketoreductase, respectively, produces a new urdamycin analogue (urdamycin X) with changes in the polyketide structure. The structure of urdamycin X has been elucidated by NMR spectroscopy. Urdamycin X was not detectable, even in small amounts, in either S. fradiae Delta urdQ, in S. fradiae DeltaurdR or in S. fradiae A0, a mutant lacking all glycosyltransferase genes. Complementation of S. fradiae Delta urdQ/R restored urdamycin A production indicating that the mutations did not cause any polar effect.

Five new peltogynoids from underground parts of Iris bungei: a Mongolian medicinal plant.

Five new peltogynoids, irisoids A-E (1-5), have been isolated from the underground parts of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods and were found to be 1,8,10-trihydroxy-9-methoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (1), 1,8-dihydroxy-9,10-dimethoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (2), 1,10-dihydroxy-8,9-dimethoxy-[1]benzopyrano-13,2-c][2]-benzopyran-7(5H)-one (3), 1,8-dihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (4), and 1,8,11-trihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (5). The structure of irisoid B (2) was established unambiguously by X-ray diffraction study.

Four new flavones and a new isoflavone from Iris bungei.

Four new irisflavones A-D (1-4) and irilin D (5) have been isolated from the underground parts of Iris bungei along with known isoflavones, irilins A-B (6-7) and tlatancuayin (8). The structures of the new compounds were determined using NMR and mass spectroscopic methods and were found to be 2',5,7-trihydroxy-3,6-dimethoxyflavone (1), 2',5-dihydroxy-3,6,7-trimethoxyflavone (2), 2',5,6'-trihydroxy-3,6,7-trimethoxyflavone (3), 3,3',5-trihydroxy-2',7-dimethoxyflavone (4), and 3',4',5,7-tetrahydroxy-6-methoxyisoflavone (5). The structures of irisflavones 1, 3, and 4 were confirmed by single-crystal X-ray diffraction studies.

New antioxidant and antimicrobial ellagic acid derivatives from Pteleopsis hylodendron.

Bioassay-guided isolation of two new compounds, 3,4-methylenedioxy-3'-O-methyl-4'-O-glucoside ellagic acid (1) and the pteleoellagic acid derivative (2), from the stem bark of Pteleopsis hylodendron is reported along with 3,4-methylenedioxy-3'-O-methyl ellagic acid (3), 3,3'-di-O-methyl ellagic acid (4) and 3,3',4'-tri-O-methyl ellagic acid (5), which were obtained for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic studies. Compounds 1 and 4 were found to have significant antioxidant activity, while compounds 1-4 showed antibacterial activity against different pathogenic bacteria.

Quinolizidine alkaloids from Sophora alopecuroides.

A new matrine-type alkaloid, 7alpha-hydroxysophoramine (1), was isolated from the aerial parts of Sophora alopecuroides together with eight known alkaloids, 12beta-hydroxysophocarpine (2), sophoramine (3), 14beta-hydroxymatrine, matrine, sophoridine, sophocarpine, adenocarpine, and baptifoline. The structures of compounds 1-3 were confirmed through single-crystal X-ray diffraction analysis.

Quinolizidine Alkaloids from Sophora alopecuroides.

A new matrine-type alkaloid, 7α-hydroxysophoramine (1), was isolated from the aerial parts of Sophora alopecuroides together with eight known alkaloids, 12ß-hydroxysophocarpine (2), sophoramine (3), 14ß-hydroxymatrine, matrine, sophoridine, sophocarpine, adenocarpine, and baptifoline. The structures of compounds 1-3 were confirmed through single-crystal X-ray diffraction analysis.

Characterization of the hypoglycemic effects of Trigonella foenum graecum seed.

The whole powder of Trigonella foenum graecum seeds and its extracts were tested for their hypoglycemic effect on normal and diabetic model rats. The powder, its methanol extract, and the residue remaining after methanol extraction had significant hypoglycemic effects when fed simultaneously with glucose. The water extract of the methanol extractive-free residue of the seed powder showed significant hypoglycemic activity at different prandial states. The Soluble Dietary Fibre (SDF) fraction showed no effect on the fasting blood glucose levels of nondiabetic or NIDDM model rats. However, when fed simultaneously with glucose, it showed a significant hypoglycemic effect (p < 0.05) in NIDDM model rats. Chemical analysis showed that the major constituent of the SDF is a galactomannan. The results confirm the involvement of SDF in the hypoglycemic effect of T. foenum graecum seeds. However, compound(s) other than SDF is (are) also involved in the hypoglycemic activity.

Hypoglycemic effects of three plants from eastern Himalayan belt.

Rhizome of Costus speciosus, tuber of Nephrolepsis tuberosa, and bulb of Stephania hernandifolia, used by the local people and traditional healers in the Eastern Himalayan belt, were studied for their effects on serum glucose levels in nondiabetic and diabetic rat models at different prandial states. The results showed that in nondiabetic rat C speciosus and N tuberosa had no significant effect in the fasting or postprandial state when freeze-dried juices were fed simultaneously with glucose. However, when fed 30 min before the glucose load both C speciosus (p < 0.05) and N tuberosa (p < 0.003) showed hypoglycemic effect. To the contrary, S hernandifolia increased the serum glucose levels of nondiabetic rats in all the series of experiments (p < 0.05 or p < 0.01). In NIDDM model rats N tuberosa opposed the rise in serum glucose level when it was fed 30 min before the glucose load (p < 0.02), whereas S hernandifolia had a tendency to raise the serum glucose level. In IDDM model rats, none of these three freeze-dried juice showed any effect in the fasting state. However, C speciosus showed significant hypoglycemic effect (p < 0.002) when the juice was fed with simultaneous glucose load. In marked contrast to the findings with nondiabetic and NIDDM model rats S hernandifolia showed significant hypoglycemic effect (p < 0.05-0.006) in both the stages (fed simultaneously with, and 30 min before the glucose load) of prandial states of the IDDM model rats. The results indicated that these three plants have interesting possibilities as a source of oral hypoglycemic agents.

Studies on hypoglycemic effects of fruit pulp, seed, and whole plant of Momordica charantia on normal and diabetic model rats.

Extracts of Momordica charantia fruit pulp, seed, and whole plant were tested for their hypoglycemic effects on normal and diabetic rat models. The results show that during the oral glucose tolerance test the peak blood glucose values in rats are obtained much earlier (15-45 min) than in human subjects (around 60 min). Pulp juice of M. charantia lowered fasting blood glucose levels in normal rats (p < 0.05 at 120 min); the effect was more pronounced with the saponin-free methanol extract of the pulp juice (p < 0.05 at 60 min and p < 0.01 at 120 min). The pulp juice also had a significant hypoglycemic effect in the glucose-fed normal rats when the extract was fed 45 minutes before the oral glucose load [percentage increments over basal value (M +/- SE): 85 +/- 10 in the control group vs. 54 +/- 7 in the pulp juice group, p < 0.01]. In the IDDM model rats the pulp juice had no significant effect on blood glucose levels either in fasting or postprandial states. In the NIDDM model rats the saponin-free methanol extract of juice produced a significant hypoglycemic effect both in fasting (p < 0.05 at 120 min) and in postprandial states (sum of percentage increments over basal value: 140 +/- 26 in the control vs. 71 +/- 7 in the pulp juice group, p < 0.05). Methanol extracts of seed and of whole plant, and saponin-free methanol extract of whole plant produced no hypoglycemic effects in normal or IDDM model rats either in fasting or in postprandial states.(ABSTRACT TRUNCATED AT 250 WORDS)