Of 25 bacterial isolates from Vietnamese soils, two were identified asBacillus stearothermophilus and one asThermoactinomyces thalpophilus, both thermophilic, amylase-producing bacteria. Amylase activity was highest in the presence of cassava starch as carbon source and (NH4)2HPO4 as nitrogen source. The strains exhibit a high amylase productivity within the first 5 to 7 h of cultivation at 55°C. The crude enzyme had optima of pH 6.5 and 70°C.
Sanchezia nobilis Hook.F. is being paid attention and studied in a lot of different ways. The research of Abu Shuaib Rafshanjani and partners about the evaluation of the safety of Brine shrimp lethality bioassay method on n-hexane and ethylacetate segments, the results showed that both segments were safer than vincristine sulphate. 1 With antimicrobial, antifungal and insecticidal testing by diffusion on agar plates with 15 strains of Gram (+) and Gram (-) bacteria; 6 strains of fungus and insects Tribolium castaleum was not as good as comparison antibiotics. 2 Mohammad javad Paydar and co-worker have tried the antioxidant effect by Oxygen Radical Antioxidant Capacity (ORAC) method, the results were nearly equal to Quercetin and anti-cancer on methanolic segment from Sanchezia speciosa extract on MCF-7, SK-MEL-5, HUVEC giving the best results on CMF-7 cell lines, the anti-cancer effect on Hela cells from the roots of Sanchezia nobilis produced good results by MTT of Nusrat Shaheen and co-worker. 3,4 Research on the antioxidant effect of DPPH and anti-inflammatory by inhibition of albumine denaturation assay method by Bui Thanh Tung and partners gave positive results. 5 Some new claims showing that Sanchezia nobilis Hook.F. contains a number of substance groups such as flavonoids, glycosides, carbohydrates, alkaloids, steroids, phenolic, saponins and tannins. Some specific substances were isolated such as 5 matsutake alcohol compounds, in which the four compounds were first isolated from the Acathanceae family and one was the first isolated from nature, 3-O-arabarabinopyranosyl-(1-6)-β-glucopyranosyl-(1-6)-β-glucopyranosyl-1-octen-3-ol and 6 other compounds from the leaf and root methnol extract, in which 1 substance was first isolated from naturally, 9-O-β-xylopyranosyl-(1→6)-O-βglucopyranosyl-(1→6)-O-β-glucopyranosyltranscinnamyl alcohol, the 4 substances were first isolated from the Acanthaceae family and 3 substances were reported for the first time from Sanchezia by Ahmed and co-worker Bui Thanh Tung and partners also isolated 4 compounds in which 3 compounds were first isolated from Sanchezia speciosa. 6-8 In Vietnam, Sanchezia are found in many localities such as
Five compounds (1-5) were isolated from the leaves of Sanchezia nobilis collected in Nam Dinh province by chromatographic methods. These compounds were identified as: mangiferin (1), β-sitosterol (2), margaric acid (3), ursolic acid (4), oleanolic acid (5). Their structures were elucidated by spectroscopic methods, including mass spectrometry and nuclear magnetic resonance. These compounds were isolated from the leaves of Sanchezia nobilis for the first time. Screening of gastric and duodenal antiulcer effects on indomethacin induced gastric ulcer models showed that n-hexane fraction produced the highest antiulcer activity. Percentage inhibition of gastric ulceration of misoprostol was 22.86 %, while that of n-hexane fraction was 28.57 % (p < 0.05). Evaluation of gastric and duodenal antiulcer effects on acysteamine induced gastric ulcer models showed that this fraction was effective against gastric and duodenal ulcer (83.3 %), improved ulcer damage (54.17 %), significantly reduced the number of mean ulcer and ulcer index (2.00 ± 1.28) but it did not change the area of the ulcer.
Two new vernonioside K (1) and vernonioside L (2) and four known Δ 7,9(11) stigmastane-type steroidal saponins-vernonioside B2 (3), vernoniacum B (4), vernonioside B1 (5), and vernoamyoside A (6)were isolated from the leaves of Vernonia amygdalina. Their structures were determined by comprehensive spectroscopic analysis with one-dimensional nuclear magnetic resonance, twodimensional nuclear magnetic resonance, and high-resolution mass spectrometry. All isolated compounds (1-6) were evaluated to determine their inhibitory effects on α-glucosidase and xanthine oxidase. Among them, two new compounds 1 and 2 showed significant inhibition of α-glucosidase with IC 50 values of 78.56 ± 7.28 and 14.74 ± 1.57 (μM), respectively, comparable with acarbose as a positive control (127.53 ± 1.73 μM); none of these compounds inhibited xanthine oxidase activity. Compounds 1 and 2 are promising candidates for the development of antidiabetic agents from natural sources.
Active-matrix thin film transistors (TFTs) on glass substrates with a metal backplane, that are applied for flat panel displays, can be considered as a metamaterial absorber. In this study, TFT structures using doped silicon at source, drain, and channel terminals are investigated. These terminals are unchanged in size of 75 µm square and thickness of 5.3 µm. The electric conductivity is varied at the channel. The simulation results show that the structures with 500 S\m electric conductivity channels absorb incident electromagnetic waves with appropriately 100% at 758 GHz and a wide bandwidth of 20 GHz. As the electrical conductivity increases, the absorption and bandwidth are smaller at the main resonance peak. As the electrical conductivity decreases, the absorption falls at the resonance frequency, but the bandwidth is broadened. In addition, the electric field in the channel may influence the electron in the semiconductor and the electrical current between the source and drain terminals. By observing the electric field at the resonance frequency, we found that it is focused on the sides of channel terminals.
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