449 research outputs found

    Triterpenoid saponins from Cortex Albiziae

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    Cortex Albiziae, the dried stem bark of a leguminous plant, Albizia julibrissin Durazz, was specified in Chinese Pharmacopoeia (1995 edit.) as a traditional Chinese medicine to be used.to relieve melancholia and uneasiness of body and mind, to invigorate the circulation of blood and subside a swelling. In a course of our quality assessment of traditional Chinese medicines, the n-BuOH soluble part of 95% EtOH extracts from the stem barks of Albizia julibrissin was subjected to a series of solvent treatment and chromatographic separations, including Rp-HPLC methods, giving rise to 28 pentacyclic triterpenoid saponins. Based on chemical methods and spectroscopic evidences, the structures of saponins were identified, which included six pairs of diastereoisomers, five pairs of position isomers, and 26 of them were new compounds. All the saponins are trisdesmosidic saponins, which are composed of an acacic acid moiety, 7-9 monosaccharide moieties, 1-2 monoterpenic acid moieties, and exhibited their molecular ion peaks around m/z 2000. Their carbon-13 signals and most of proton signals were assigned based on 1D and 2D NMR experiments. The proton and carbon signals of several known saponins were revised and reassigned. The spectroscopic properties related to these saponins were analyzed and summarized. The cytotoxic activity and other activities of these saponins and their analogues were discussed also.この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されまし

    Temperature Matrix-Based Data Placement Optimization in Edge Computing Environment

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    The scale of data shows an explosive growth trend, with wide use of cloud storage. However, there are challenges such as network latency and energy consumption. The emergence of edge computing brings data close to the edge of the network, making it a good supplement to cloud computing. The spatiotemporal characteristics of data have been largely ignored in studies of data placement and storage optimization. To this end, a temperature matrix-based data placement method using an improved Hungarian algorithm (TEMPLIH) is proposed in this work. A temperature matrix is used to reflect the influence of data characteristics on its placement. A data replica matrix selection algorithm based on temperature matrix (RSA-TM) is proposed to meet latency requirements. Then, an improved Hungarian algorithm based on replica matrix (IHA-RM) is proposed, which satisfies the balance among the multiple goals of latency, cost, and load balancing. Compared with other data placement strategies, experiments show that the proposed method can effectively reduce the cost of data placement while meeting user access latency requirements and maintaining a reasonable load balance between edge servers. Further improvement is discussed and the idea of regional value is proposed

    Effect of Different Drying Methods on Physicochemical Properties and Antioxidant Activities of Postharvest Okra Pods

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    Effects of hot-air drying (HD) and microwave drying (MD) methods on the physicochemical properties and antioxidant activities of postharvest okra was investigated. The weight loss rate and the contents of vitamin C, chlorophyll a, protein, soluble pectin as well as antioxidant activities of okra pods were determined. The results showed that HD and MD methods had significant influences on the physicochemical properties and antioxidant activities. The weight loss rate of okra treated by HD method was 87.45%, and it was 75.04% treated by MD. Both of them presented lower contents of chlorophyll a with a ranges of 0.33 ± 0.01 mg/g and 0.23 ± 0.02 mg/g. The protein contents of the HD was 16.38 ± 0.49%, and 9.16 ± 0.11% for MD method. The soluble pectin contents were 29.1 ± 0.76 mg/g and 28.26 ± 0.57 mg/g for HD and MD methods, respectively. It indicated that the nutrients in okra pods are susceptible to thermal processing, and the high temperature will significantly reduce the nutritional value. The specific conditions for different thermal processes should be studied and optimization

    Research on improving development effect of high-saturated reservoir in the late stage of water-flooding

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    High-saturated reservoir is characterized by high saturation pressure and high gas-oil ratio. The effects of water flooding are easily influenced by the formation pressure and GOR, especially at the late stage. This article presents the relationship between the reasonable pressure maintenance level and GOR as well as water cut based on the actual characteristics of high-saturated reservoir. Then, the reservoir numerical simulation method is used to analyse the influence of pressure recovery rate and water cut rise under different injection-production ratios and injection-production methods. Research results show that the pressure maintenance level of high-saturated reservoir is larger than normal reservoirs. Bigger injection-production ratio results in not only faster pressure recovery rate but also higher water cut. Cyclic injection and production method under the maximum injection rate and liquid extraction amount can enhance oil recovery rate and control water cut rise at the same time, which plays a significant role in improving the development effect of water-flooding in high-saturated reservoirs at the late stage

    Manipulation of host immune defenses by effector proteins delivered from multiple secretion systems of Salmonella and its application in vaccine research

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    Salmonella is an important zoonotic bacterial species and hazardous for the health of human beings and livestock globally. Depending on the host, Salmonella can cause diseases ranging from gastroenteritis to life-threatening systemic infection. In this review, we discuss the effector proteins used by Salmonella to evade or manipulate four different levels of host immune defenses: commensal flora, intestinal epithelial-mucosal barrier, innate and adaptive immunity. At present, Salmonella has evolved a variety of strategies against host defense mechanisms, among which various effector proteins delivered by the secretory systems play a key role. During its passage through the digestive system, Salmonella has to face the intact intestinal epithelial barrier as well as competition with commensal flora. After invasion of host cells, Salmonella manipulates inflammatory pathways, ubiquitination and autophagy processes with the help of effector proteins. Finally, Salmonella evades the adaptive immune system by interfering the migration of dendritic cells and interacting with T and B lymphocytes. In conclusion, Salmonella can manipulate multiple aspects of host defense to promote its replication in the host
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