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921.
Xiaoying He Yonglin Yu Dexiu Huang Ruikang Zhang Wen Liu Shan Jiang 《Optics Communications》2008,281(3):415-420
An analytical method is proposed for calculating reflection-spectrum envelope of interleaved sampled gratings with phase-shifts. Effects of parameters on reflection-spectrum envelope of the grating are discussed, such as two grating segment lengths, phase-shift and interleaved length. The unique optimal interleaved length can be obtained to provide the broadest flat-top reflection-spectrum envelope without ripples. Accuracy of the analytical expression is verified due to the calculated results in good agreement with the reflection spectra obtained by the piecewise uniform transform matrix method. 相似文献
922.
Supachoke Mangmool Chayaporn Limpichai Khine Kyi Han Vichai Reutrakul Natthinee Anantachoke 《Molecules (Basel, Switzerland)》2022,27(10)
Mitrephora sirikitiae Weeras., Chalermglin & R.M.K. Saunders has been reported as a rich source of lignans that contribute to biological activities and health benefits. However, cellular anti-inflammatory effects of M. sirikitiae leaves and their lignan compounds have not been fully elucidated. Therefore, this study aimed to investigate the anti-inflammatory activities of methanol extract of M. sirikitiae leaves and their lignan constituents on lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 mouse macrophage cells. Treatment of RAW 264.7 cells with the methanol extract of M. sirikitiae leaves and its isolated lignans, including (−)-phylligenin (2) and 3′,4-O-dimethylcedrusin (6) significantly decreased LPS-induced prostaglandin E2 (PGE2) and nitric oxide (NO) productions. These inhibitory effects of the extract and isolated lignans on LPS-induced upregulation of PGE2 and NO productions were derived from the suppression of cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) production, respectively. In addition, treatment with 2-(3,4-dimethoxyphenyl)-6-(3,5-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (3) and mitrephoran (5) was able to suppress LPS-induced tumor necrosis factor alpha (TNF-α) secretion and synthesis in RAW 264.7 cells. These results demonstrated that M. sirikitiae leaves and some isolated lignans exhibited potent anti-inflammatory activity through the inhibition of secretion and synthesis of PGE2, NO, and TNF-α. 相似文献
923.
Xinjun Yu Zengchao Jiang Xiaodan Xu Changyi Huang Zheyi Yao Xiao Yang Yinjun Zhang Dongsheng Wang Chun Wei Xuwei Zhuang 《Molecules (Basel, Switzerland)》2022,27(15)
Chitin, the second richest polymer in nature, is composed of the monomer N-acetylglucosamine (GlcNAc), which has numerous functions and is widely applied in the medical, food, and chemical industries. However, due to the highly crystalline configuration and low accessibility in water of the chitin resources, such as shrimp and crab shells, the chitin is difficult utilize, and the traditional chemical method causes serious environment pollution and a waste of resources. In the present study, three genes encoding chitinolytic enzymes, including the N-acetylglucosaminidase from Ostrinia furnacalis (OfHex1), endo-chitinase from Trichoderma viride (TvChi1), and multifunctional chitinase from Chitinolyticbacter meiyuanensis (CmChi1), were expressed in the Pichia pastoris system, and the positive transformants with multiple copies were isolated by the PTVA (post-transformational vector amplification) method, respectively. The three recombinants OfHex1, TvChi1, and CmChi1 were induced by methanol and purified by the chitin affinity adsorption method. The purified recombinants OfHex1 and TvChi1 were characterized, and they were further used together for degrading chitin from shrimp and crab shells to produce GlcNAc through liquid-assisted grinding (LAG) under a water-less condition. The substrate chitin concentration reached up to 300 g/L, and the highest yield of the product GlcNAc reached up to 61.3 g/L using the mechano-enzymatic method. A yield rate of up to 102.2 g GlcNAc per 1 g enzyme was obtained. 相似文献
924.
925.
《Arabian Journal of Chemistry》2023,16(6):104723
Imidacloprid and sulfoxaflor have potential damage to nontarget aquatic organisms. However, limited information has been provided on their underlying toxicity effects on Rana nigromaculata tadpoles. Thus, the acute toxicity and chronic effects of imidacloprid and sulfoxaflor on R. nigromaculata tadpoles were studied. Acute toxicity indicted that 96 h for LC50 values of imidacloprid and sulfoxaflor were 173.55 and 427.37 mg/L, respectively. In this research, we explored antioxidant enzymes, some biological indexes, hormone levels and expression of relative tadpole genes involved in thyroid hormone-dependent metaplastic development after exposure for 28 days under 1/10 and 1/100 LC50. Results showed an increase in the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in the tadpoles, and a low bioconcentration level with a bioconcentration factor (BCFs) < 1. The impact on the development of tadpoles was induced by the breakdown of hormonal levels engaged in metamorphosis. According to the real-time PCR results, imidacloprid and sulfoxaflor delayed amphibian metamorphosis by modifying mRNA expression, indicating that imidacloprid and sulfoxaflor may have an endocrine-disrupting effect on R. nigromaculata tadpoles. These findings were indicative of the toxicity of imidacloprid and sulfoxaflor to R. nigromaculata tadpoles. 相似文献
926.
本文主要结果为定理2.由此可推出一种迭代算法.此外,还讨论了连摹乘并形式,从而嘉量原理得到进一步推广. 相似文献
927.
Mingyue He Lidong Yu Xueting Li Shuang Ma Ning Gu Jianbo Jia Bingsheng Li Li Li 《Particle & Particle Systems Characterization》2023,40(1):2200143
The possible detrimental effects of nanomaterials on organisms have become a public concern because of the wide applications of nanomaterials in modern society. This study investigates the effects of silica nanoparticles (nano-SiO2) on zebrafish development. Fluorescent nano-SiO2 (FITC-nano-SiO2) is synthesized with an emission wavelength of 517 nm. Due to similar hydrodynamic size, FITC-nano-SiO2 is used to simulate the distribution of nano-SiO2 in zebrafish. Nano-SiO2 regulated col2a1a, col9a2, lect1, and her12 to delay liver development and regulated prox, wnt2bb, mypt1, and hhex caused spinal curvature. The hand2, mef2a, nkx2.5, and atp1a2a are significantly down-regulated. The whole embryo in situ hybridization revealed amhc and flk1 are also down-regulated. This suggests that nano-SiO2 affected heart and blood vessels development of zebrafish. Furthermore, it is found that cell apoptosis occurred in the heart. The proapoptotic genes (bax, bid) are upregulated, and the antiapoptotic genes (bcl-2, mcl-1b) are down-regulated. Nano-SiO2 increases the endoplasmic reticulum (ER) stress-related genes (chop, bip, perk, elF2α), indicating that the ER stress is involved in cell apoptosis. This study provides a toxicological basis for evaluating the possible hazards of nano-SiO2 to aquatic organisms. 相似文献