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Jiang W.,Jilin University | Liu J.,Jilin University | Tao X.,Jilin University | Wang Y.,Jilin Province Product Quality Supervision Test Institute | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

To obtain the optimal essential oils extraction conditions with supercritical carbon dioxide, uniform design and the artificial neural network (back propagation, BP) were applied in extraction of ledum palustre L. Number of neuron in hide layer and some functions for learning, training and transfer were chosen through one-factor experimental design. Four factors (six levels in each factor) were considered in uniform design. Five factors (extraction time, extraction temperature, extraction pressure, particle size, kind of leaves or stems) were considered in BP network. The average error of network prediction was 0.0116. Analysis of correlation and comparison showed that the experimental values and the predicted values were not significant. The effect of each factor on extraction yield and the optimal extraction conditions were studied with this model. The highest extraction yield of essential oils from ledum palustre L. stems could reach 1.82% at 17.5°C, 375 bar for 1 h while the essential oils extraction yield of ledum palustre L. leaves was 2.65% at 15°C, 275 bar for 3 h. It may provide a new study method for the extraction of volatile oil of ledum palustre L. Source


du Y.,Changchun University of Technology | Zhang J.,Jilin Province Product Quality Supervision Test Institute | Zhou C.,Changchun University of Technology
Polymer Bulletin | Year: 2015

Waterborne polyurethanes (WPUs) derived from polytetramethylene ether glycol (PTMG), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,4-butanediol and dimethylolpropionic acid were synthesized. Hydroxyl-terminated polydimethylsiloxane (PDMS) was introduced to replace part of PTMG as soft segment. The effects of [–NCO]/[–OH] (R value) and PDMS content on structure and properties of WPU were studied using FTIR, thermal analysis, mechanical test, contacting angle testing and scan electron microscopy (SEM). The results revealed that the trend of particles fusion in WPU film decreased with the increment of R value by SEM photos. The replacement of PTMG by PDMS led to an obvious change in surface properties of films and distinct phase separation was observed by SEM photos when the PDMS content increased. This is the result when the content of PDMS was 2.0 wt% and R value is 1.2, the film exhibited excellent mechanical properties with the highest elongation at break and improved tensile strength. © 2015 Springer-Verlag Berlin Heidelberg Source


Yu W.-X.,Jilin University | Hua L.-G.,Jilin Province Product Quality Supervision Test Institute | Yu S.-S.,Jilin University | Zhao Z.-D.,Jilin University
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2010

Poly(vinylidene fluoride) (PVDF)/multiwalled carbon nanotube (MWCNT) composites were prepared by ultrasonic dispersion process. The morphology, conductivity and thermal expansion of these composites were studied. Scanning electronic microscopy observations indicate that the MWCNTs are uniformly dispersed in the PVDF matrices. There is an interaction between MWCNT and PVDF, but no chemical crosslinking is detected in the sonicated composites. The measurements of conductive properties show that the composites have a low percolation threshold and exhibit high levels of electrical conductivity. Positive temperature coefficient effect of the composite with 1.5% MWCNT loading was also investigated. Furthermore, the addition of MWCNTs into PVDF matrices significantly decreases the coefficient of thermal expansion of the composites. Source


Chai B.,Jilin University | Xiang Y.,Jilin Province Product Quality Supervision Test Institute | Ma W.,Jilin University | Yu C.,Jilin University | Kou Z.,Jilin University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Hydrodynamic coupling is used for power transmission in heavy duty drives, such as power stations, ship propulsion, band conveyers, mills, and larger transport vehicles. Their hydrodynamic principle enables a low-wear torque to convert from a drive to a load. The flow in a hydrodynamic coupling is one of the most complex problems encountered in engineering fluid mechanics. The external performance of hydrodynamic coupling is determined by its internal distribution of flow field. It is very important to make a deep research on the internal distribution of flow field for the performance improvement and structural optimization in the design of hydrodynamic coupling. Numerical simulation is a main way to study the internal flow field of hydrodynamic coupling. The results of numerical simulation that are calculated by different turbulence models are quite different. In order to obtain accurate and reliable results of numerical simulation, it is a key to choose a reasonable turbulence model. The integrated computer engineering and manufacturing (ICEM) software was used to mesh the whole flow channel model of hydrodynamic coupling by hexahedral grids, and the total mesh number was 470 944 and the number of nodes was 521 887. Numerical simulation of three-dimensional unsteady turbulent flows in hydrodynamic coupling was carried out by numerically solving the Navier-Stokes equations in a rotating coordinate system. In order to analyze the applicability of different turbulence models in the calculation of flow field in hydrodynamic coupling, 3 different turbulence models (standard k-ε model, detached eddy simulation model, large eddy simulation model) were chosen to simulate the internal flow field of square cavity hydrodynamic coupling under braking condition. The quantity and quality of mesh was consistent during the numerical simulation of different turbulence models. The velocity field and vorticity field of radial section in hydrodynamic coupling were simulated and extracted through ANSYS CFX software. In addition, the transparent prototype of hydrodynamic coupling was manufactured and used in the complex flow test experiment, the internal flow field of hydrodynamic coupling under braking condition was tested based on particle image velocimetry (PIV), the characteristics of flow images were extracted by image processing technique, and the velocity field and vorticity field of radial cross-section were calculated by image cross correlation algorithm. Then numerical simulation and PIV experimental results were compared. The PIV test results were used as the evaluation criteria, and the differences of numerical simulation results by 3 kinds of turbulence models were analyzed. Moreover, the applicability of 3 turbulence models was analyzed. The results showed that the simulation results by standard k-ε model were far different from PIV experimental results, the distribution of flow field in main flow region simulated by the large eddy simulation model was much more real than others, the simulation results could be used to explain the law of multi-scale vortex movement and the mechanism of energy dissipation in the main flow region, and the high-gradient flow field distribution of near-wall area and corner area could be captured more accurately by the detached eddy simulation model. The results of analysis will provide a basis for accurate calculation of flow field and performance prediction of hydrodynamic coupling. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved. Source


Lin Y.,Jilin University | Cui M.,Jilin University | Shi Y.,Jilin Province Product Quality Supervision Test Institute | Wang F.,Jilin University | And 2 more authors.
African Journal of Biotechnology | Year: 2011

The pathogenesis of ovarian cancer remains poorly understood. Genome-wide gene expression profiling can provide novel genetic data involved in the pathogenesis of disease. In this study, using normal ovarian surface epithelium and abnormal ovarian surface epithelium of patients with ovarian cancer as models for cDNA microarray analysis, we found that cyclooxygenase-2(COX-2) expression of patients with ovarian cancer was increased. This result was further confirmed by semi-quantitative RTPCR and Western blot. It was found that COX-2 was significantly up-regulated in ovarian cancer group in comparison with normal group on mRNA level. On protein level, COX-2 was also highly increased in ovarian cancer group. This study provides novel candidate molecules and suggests a potential local role for COX-2 as mediators of ovarian cancer and as markers of disease activity. © 2011 Academic Journals. Source

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