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11.
Three new steroidal glycosides named cynascyrosides A-C were isolated from the roots of Cynanchum ascyrifolium. The structures of these compounds were determined on the basis of spectroscopic and chemical evidence as cynajapogenin A 3-O-alpha-D-oleandropyranosyl-(1-->4)-beta-L-cymaropyranosyl -(1-->4)-beta-D- digitoxopyranoside; cynajapogenin A 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-cymaropyranosyl- (1-->4)-beta-L-cymaropyranosyl-(1-->4)-beta-L-cymaropyranoside+ ++; cynajapogenin A 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-cymaropyranosyl- (1-->4)-beta-D-digitoxopyranosyl-(1-->4)-beta-L-cymaropyranosid e. 相似文献
12.
Feng Zhong Chai Kiat Yeo Bu Sung Lee 《Journal of Network and Computer Applications》2012,35(1):316-327
In places where mobile users can access multiple wireless networks simultaneously, a multipath scheduling algorithm can benefit the performance of wireless networks and improve the experience of mobile users. However, existing literature shows that it may not be the case, especially for TCP flows. According to early investigations, there are mainly two reasons that result in bad performance of TCP flows in wireless networks. One is the occurrence of out-of-order packets due to different delays in multiple paths. The other is the packet loss which is resulted from the limited bandwidth of wireless networks. To better exploit multipath scheduling for TCP flows, this paper presents a new scheduling algorithm named Adaptive Load Balancing Algorithm (ALBAM) to split traffic across multiple wireless links within the ISP infrastructure. Targeting at solving the two adverse impacts on TCP flows, ALBAM develops two techniques. Firstly, ALBAM takes advantage of the bursty nature of TCP flows and performs scheduling at the flowlet granularity where the packet interval is large enough to compensate for the different path delays. Secondly, ALBAM develops a Packet Number Estimation Algorithm (PNEA) to predict the buffer usage in each path. With PNEA, ALBAM can prevent buffer overflow and schedule the TCP flow to a less congested path before it suffers packet loss. Simulations show that ALBAM can provide better performance to TCP connections than its other counterparts. 相似文献
13.
Dinesh Kalyanasundaram Shinnosuke Inoue Jong-Hoon Kim Hyun-Boo Lee Zenko Kawabata Woon-Hong Yeo Gerard A. Cangelosi Kieseok Oh Dayong Gao Kyong-Hoon Lee Jae-Hyun Chung 《Microfluidics and nanofluidics》2012,13(2):217-225
Simple, high-yield concentration of DNA is important for high-throughput genetic analysis and disease diagnosis. Glass-based microfilters are popular but the process requires centrifugation steps with cumbersome chemical processes. As an alternative, a concentration method using an electric field has been explored previously, but with limited efficiency. In this paper, electric field-induced concentration and capture of DNA are studied by using high-aspect-ratio microtips coated with a gold layer. The microtips are immersed longitudinally into a solution of 100???L containing ??-phage DNA. After DNA concentration using an electric field, the microtips are withdrawn from the solution. Under AC- and biased AC fields, DNA is concentrated by electrophoresis (EP), dielectrophoresis (DEP), and electroosmotic flow (EOF). To reduce capillary effects in the withdrawal process, the microtips are coated with positively charged poly-l-lysine (PLL). The pattern of captured DNA is analyzed by fluorescence microscopy. DEP attracts DNA molecules at the edges of microtips, where the highest gradient of electric field exists. EP attracts DNA onto the surface of microtips following the vectors of an electric field. EOF generates vortexes that deliver DNA onto microtips. Using this method, 85% of DNA is captured on the PLL-coated microtips after three sequential captures. The concentration mechanism can potentially facilitate rapid and simple preparation of DNA for downstream analysis. 相似文献
14.
15.
Natural manganese ores were selected as raw materials for the desulfurization sorbent because of economical efficiency and high reactivity on hydrogen sulfide. Initial reaction rates between H2S and desulfurization sorbent of natural manganese ores were determined in a temperature range of 400-800°C using a thermobalance reactor. All reactions were first order with respect to H2S and were expressed by the Arrhenius relation. When the sulfidation reaction was controlled by diffusion, the temperature dependence of the effective diffusivity was given by the Arrhenius equation. Activation energies and frequency factors were obtained from the product layer diffusion coefficient of various sorbents by plotting as an Arrhenius equation form. Several additives were mixed to improve the sulfidation capacity, and NiO was the best additive. 相似文献
16.
In this work mathematical models were developed to represent the kinetics of volume changes of fluid spaces associated with
infusion of Ringer’s solution. During infusion of Ringer’s solution, the human body is assumed to be characterized by the
two-fluid space model which has second volume space in addition to the first volume so that fluid exchanges between these
two spaces are possible. Various infusion types were tested to accommodate different medical situations. Volunteers were given
Ringer’s solution and the changes in blood hemoglobin were detected. From the comparison with experimental data, the two-fluid
space model was found to represent adequately the kinetics of human volume expansion during infusion of Ringer’s solution. 相似文献
17.
A model representing the wet-end section of a paper mill has been developed to characterize its dynamic behavior during the
grade change. The model is based on the mass balance relationships written for the simplified wetend white water network.
From the linearization of the dynamic model, higher-order Laplace transfer functions were obtained followed by the reduction
procedure to give simple lower-order models in the form of 1st-order or 2nd-order plus dead times. The dynamic response of the wet-end is influenced both by the white water volume and by the level
of wire retention. Effects of key manipulated variables such as the thick stock flow rate, the ash flow rate and the retention
aid flow rate on the major controlled variables were analyzed by numerical simulations. The simple dynamic model developed
in the present study can be effectively used in the operation and control.
This paper is dedicated to Professor Se Ki Moon on the occasion of his retirement from Hanyang University. 相似文献
18.
The High-Performance Computing (HPC) is an infrastructure to support various research fields. The research using HPC requires big storage for large-scale of raw data and the huge computing resources to analyze. The consolidated operations of the computing center for supporting various researches using HPC are a very effective organization. The consolidated operations are able to increase the utilization. The computing center has to be re-organized continuously in order to support the various fields of research effectively and flexibly. Re-organization to reuse the limited resources enforces the update of the information for verification of the computing resources after the re-allocation of computing resources and the re-distribution of trusted connection between computing resources. Consequently, to maintain effective research support we need automated resource re-organization environment. In this paper, we build an automated update of the trusted connection for re-organized computing resource using puppet which is automated system management platform. Finally, we provide a unified verification point and efficient environment for the re-allocation and re-organization of the integrated computing center. 相似文献
19.
Yong?Rae?Chae Yeo?Joon?Yoon Keun?Garp?RyuEmail author 《Korean Journal of Chemical Engineering》2004,21(5):999-1002
Expanded bed behavior was modeled by using the Richardson-Zaki correlation between the superficial velocity of the feed stream and the void fraction of the bed. A polydisperse material, Chelating excellose® (70-210 Μm in diameter, 1.21 g/cm3 in density), which has Ni2+ ions for the selective binding of histidine-tagged proteins, was used as the resin. A method to modify the Stokes expression to express the terminal settling velocity of the resins by introducing two empirical parameters, the effective diameter of the resins and an exponent for(ρ p -ρ)/Μ term, was developed. Combined use of the Richardson-Zaki correlation and the modified Stokes expression was successful in modeling the bed expansion by incorporating physical properties of feed streams and the resins. 相似文献
20.
Yeong-Koo Yeo Jong Ho Park See-Han Park Changman Sohn 《Korean Journal of Chemical Engineering》2005,22(3):339-344
In this work, the Model Algorithmic Control (MAC) method is applied to control the grade change operations in paper mills.
The neural network model for the grade change operations is identified first and the impulse model is extracted from the neural
network model. Results of simulations for MAC control of grade change operations are compared with plant operation data. The
major contribution of the present work is the application of MAC in the industrial plants based on the identification of neural
network models. We can confirm that the proposed MAC method exhibits faster responses and less oscillatory behavior compared
to the plant operation data in the grade change operations. 相似文献