Wyniki wyszukiwania - BazTech

1

Development and validation of a high-performance size-exclusion chromatography method for polymer determination in cefmetazole sodium for injection

Zhong J., Chen Y. C., Liu X. Y.

Acta Chromatographica

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2017

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Vol. 29, no. 2

193--205

EN

This study aims to develop and validate a high-performance size-exclusion chromatography (HPSEC) method to determine the amount of polymer in cefmetazole sodium for injection and to compare this method with gel chromatography. A Zenix SEC-150 column was used with the mobile phase of phosphate buffer solution (pH 7.0; 0.01 M)—acetonitrile (90:10 v/v) at a flow rate of 0.8 mL min−1 and a detection wavelength of 240 nm. The polymer was quantified by an external standard method with self-control, and the amount was expressed by the percentage of cefmetazole. The HPSEC method was validated for specificity, linearity, and precision. The chromatographic conditions, chromatographic performances, sensitivity, linearity, and precision of the developed HPSEC method and gel chromatography were compared, and both methods were subsequently used to determine the amount of polymer from seven batches of samples. The HPSEC method was fully validated. The time of isocratic elution for sample assay was less than 14 min. The results of comparison indicate that the developed HPSEC method was superior to gel chromatography. The Student t test results also showed significant difference in the amount of polymer from the samples obtained by the two methods. Thus, the HPSEC method with two obvious advantages, the superior sensitivity and a shorter analysis time, is more suitable for determination of polymer amount in cefmetazole sodium for injection to control the quality of the product.

2

Impact of local property variations of reactor coolant on cladding temperature distribution in supercritical water reactors

Zhong J., Antal S. P., Podowski M. Z.

Journal of Power Technologies

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2014

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Vol. 94, nr 5

51--60

EN

Fluids at supercritical pressures are considered to be very promising as coolants for Generation IV reactor systems, including the supercritical water cooled reactor (SCWR), the CO2-cooled reactor (SCCO2R) and the Brayton cycle as a secondary system in sodium-cooled fast reactors. The operating conditions of such reactors allow for a significant thermodynamic efficiency increase of the respective power plants. On the other hand, several unresolved issues must still be addressed in order to develop a viable design of supercritical fluid nuclear systems. Examples include: in-core heat transfer in SCWRs, heat exchangers in the S-CO2 Brayton cycle, and flows in complex geometries of SCO2 compressors. It has been shown before that the understanding of the effect of fluid property variations on turbulence is a major factor in our ability to predict the combined fluid mechanics and heat convection in systems and components using supercritical fluids. The objective of this paper is to present the results of analysis on the effect of local multidimensional flow and heat transfer phenomena on the temperature distribution inside future SCWRs. Two proposed SCWR designs have been considered: a single-pass and a two-pass coolant flow configurations through the reactor core. It should be noted that a preliminary documentation of the results of the current work has been included in the materials of the NURETH-15 conference.

3

Improving the stability of discretization zeros with the Taylor method using a generalization of the fractional-order hold

Zeng C., Liang S., Zhang Y., Zhong J., Su Y.

International Journal of Applied Mathematics and Computer Science

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2014

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Vol. 24, no. 4

745--757

EN

Remarkable improvements in the stability properties of discrete system zeros may be achieved by using a new design of the fractional-order hold (FROH) circuit. This paper first analyzes asymptotic behaviors of the limiting zeros, as the sampling period T tends to zero, of the sampled-data models on the basis of the normal form representation for continuous-time systems with a new hold proposed. Further, we also give the approximate expression of limiting zeros of the resulting sampled-data system as power series with respect to a sampling period up to the third order term when the relative degree of the continuous-time system is equal to three, and the corresponding stability of the discretization zeros is discussed for fast sampling rates. Of particular interest are the stability conditions of sampling zeros in the case of a new FROH even though the relative degree of a continuous-time system is greater than two, whereas the conventional FROH fails to do so. An insightful interpretation of the obtained sampled-data model can be made in terms of minimal intersample ripple by design, where multirate sampled systems have a poor intersample behavior. Our results provide a more accurate approximation for asymptotic zeros, and certain known results on asymptotic behavior of limiting zeros are shown to be particular cases of the ideas presented here.

4

An Integrated SVM and Fuzzy AHP Approach for Selecting Third Party Logistics Providers

Chen J., Zhong J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 9b

5-8

EN

The selection of third party logistics (3PL) providers is an important issue for enterprises to outsource their logistics business. In this paper, a new integrated model is put forward for selecting 3PL providers based on support vector machine (SVM) and fuzzy analytic hierarchy process (FAHP). In the first stage, the support vector machine (SVM) is used to classify the primary 3PL provider samples into four types which are excellent, good, medium and bad respectively. Then we can obtain the excellent samples which are the candidates for the second stage selection. In the second stage, the FAHP is used to evaluate the selected excellent samples in the first stage, so we can obtain the sorting results for the excellent samples and the optimal samples. The results of the case study show that the model is reasonable and effective and it can provide an important reference for enterprises to select 3PL providers.

PL

W artykule przedstawiono nowy zintegrowany model umożliwiający przyśpieszenie selekcji dostawcy 3PL (third party logistics). Model wykorzystuje metodę SVM (suport vector machine) i FAHP (fuzzy analytic hierarchy proces).

5

Oscillation criteria for a class of third-order nonlinear neutral differential equations

Zhong J., Ouyang Z., Zou S.

Journal of Applied Analysis

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2011

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Vol. 17, nr 2

155-163

EN

A class of third-order nonlinear neutral differential equation (r(t)(y"(t)) α)' + q(t) f(x(σ (t))) = 0 is investigated in this paper, where y(t) = x(t) + p(t)x(?(t)), and ? > 0 is any quotient of odd integers. Using a new method, we obtain some sufficient conditions for the oscillation of the above equation, and some known oscillation criteria be extended. An example is inserted to illustrate the result.