期刊文献+
共找到34篇文章
< 1 2 >
每页显示 20 50 100
基于混合冷剂离心压缩机控制系统难点分析
1
作者 肖正 《广州化工》 CAS 2014年第12期172-174,共3页
混合冷剂压缩机是整个工艺流程的关键设备,压缩机能否正常达到工况直接决定产品的品质及运行的能耗。针对低浓度含氧煤层气深冷液化混合冷剂制冷单元能安全有效的提供冷源,本文着重介绍离心压缩机组工作原理、工艺流程、控制系统配置及... 混合冷剂压缩机是整个工艺流程的关键设备,压缩机能否正常达到工况直接决定产品的品质及运行的能耗。针对低浓度含氧煤层气深冷液化混合冷剂制冷单元能安全有效的提供冷源,本文着重介绍离心压缩机组工作原理、工艺流程、控制系统配置及组成,并对机组的定气量/气压、防喘振控制方案及控制难点进行详细阐述。 展开更多
关键词 混合冷剂 离心压缩机 定气量 气压 防喘振 控制系统
下载PDF
Turbulence regime near the forest floor of a mixed broad leaved/Korean pine forest in Changbai Mountains 被引量:5
2
作者 张军辉 丁之慧 +2 位作者 韩士杰 邹春静 周玉梅 《Journal of Forestry Research》 SCIE CAS CSCD 2002年第2期119-122,164,共4页
The measurement and observation for this study were carried out by using a three-dimensional (u, v, w) Sonic anemometer (IAP-SA 485), at Forest Ecosystem Opened Research Station of Changbai Mountains (12828扙 and 4224... The measurement and observation for this study were carried out by using a three-dimensional (u, v, w) Sonic anemometer (IAP-SA 485), at Forest Ecosystem Opened Research Station of Changbai Mountains (12828扙 and 4224?N, Jilin Province, P. R. China) in August 2001. The basic characteristics of turbulence, such as turbulence intensity, atmospheric stability, time scales, and convection state, near the forest floor were analyzed. It is concluded that the airflow near forest floor is characterized by high intermittence and asymmetry, and the active and upward movement takes the leading position. Near forest floor, the vertical turbulence is retained and its time scale and length scale are much less than that of u, v components. The eddy near forest floor shows a flat structure and look like a ’Disk’. Buoyancy plays a leading role in the generation and maintenance of local turbulence 展开更多
关键词 Forest floor Velocity statistics Atmospheric stability Convection states
下载PDF
INSTABILITY OF THE TELECONNECTION OF SUMMER RAINFALLS BETWEEN NORTH CHINA AND INDIA 被引量:2
3
作者 黄建斌 王绍武 《Journal of Tropical Meteorology》 SCIE 2007年第1期1-7,共7页
Summer rainfall variations in North China closely relate to that in India. It seems that an alternation of signs of“+, -, +” exists in the geographical pattern of the correlation in summer rainfall from North Chin... Summer rainfall variations in North China closely relate to that in India. It seems that an alternation of signs of“+, -, +” exists in the geographical pattern of the correlation in summer rainfall from North China to India through the Tibetan Plateau. However, it appears that the teleconnection of summer rainfall variations between North China and India is unstable. Over 1945 - 1974, the correlation coefficient (hereafter as CC) is as large as 0.7. In contrast, the CC is about -0.3 over 1827-1856. Further studies, based on observations starting from 1813, showed that the correlation is strong when summer rainfalls in both North China and India are large, and vice versa. In order to find what induce the change of the teleconnection, variations of summer rainfall in both North China and India, mean sea surface temperature (SST) in the eastern equatorial Pacific and the frequency of ENSO events were examined in relation to the change of the teleconnection. The result showed that the teleconnection appears weak when the mean SST is high and the frequency ofLa Nifia events is low; the teleconnection is strong when the mean SST is low and the frequency ofLa Nina events is high. At last, it is notable that La Nifia happens in only 3 years during the recent 30 years from 1976 to 2005 and the teleconnection becomes weak too. 展开更多
关键词 North China INDIA summer rainfall TELECONNECTION INSTABILITY
下载PDF
Quantitative assessment of flight safety under atmospheric icing conditions 被引量:3
4
作者 Zhou Li Xu Haojun +1 位作者 Su Chen Lin Min 《High Technology Letters》 EI CAS 2012年第1期90-95,共6页
A quantitative assessment method is proposed to sense the specific effects of atmospheric icing conditions on flight safety. A six degree-of-freedom computational flight dynamics model is used to study the effects of ... A quantitative assessment method is proposed to sense the specific effects of atmospheric icing conditions on flight safety. A six degree-of-freedom computational flight dynamics model is used to study the effects of ice accretion on aircraft dynamics, and a pilot model is also involved. In order to investigate icing severity under different icing conditions, support vector regression is applied in establishing relationship between aircraft icing parameter and weather conditions. Considering the characteristics of aircraft icing accidents, a risk probability assessment model optimized by the particle swarm method is developed to measure the safety level. In particular, angle of attack is chosen as a critical parameter in this method. Results presented in the paper for a series of simulation show that this method captures the basic effects of atmospheric icing conditions on flight safety, which may provide an important theoretical reference for icing accidents avoidance. 展开更多
关键词 atmospheric icing conditions flight safety quantitative assessment risk probability supportvector regression particle swarm optimization
下载PDF
Orientation and Motion of Water Molecules at Air/Water Interface 被引量:2
5
作者 Wei Gan Dan Wu +2 位作者 Zhen Zhang Yuan Guo Hong-fei Wang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2006年第1期20-24,共5页
Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation (SFG) vibrational peak of the free O-H stretching band... Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation (SFG) vibrational peak of the free O-H stretching band at 3700 cm^-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interracial water molecule is tilted around 33°from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interracial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orient, ational motion of a liquid interface by Wei et al. (Phys. Rev. Lett. 86, 4799, (2001)) using single SFG experimental configuration. 展开更多
关键词 Air/water interface Water molecules Orientation and motion
下载PDF
Approach to increasing the quality of pressure-relieved gas drained from protected coal seam using surface borehole and its industrial application 被引量:14
6
作者 Yingke Liu Fubao Zhou +1 位作者 Jianlong Wang Jun Liu 《International Journal of Coal Science & Technology》 EI 2015年第1期46-51,共6页
During mining of lower protective coal seam, a surface borehole can efficiently extract not only the pressure-relieved gas from the protected layer, but also the gas from the mining layer gob. If the distance between ... During mining of lower protective coal seam, a surface borehole can efficiently extract not only the pressure-relieved gas from the protected layer, but also the gas from the mining layer gob. If the distance between the borehole and gob is too large, the quantity of gas drained from the protected layer decreases substantially. To solve this problem, a mathematical model for extracting pressure-relieved gas from a protected coal seam using a surface borehole was established, based on the radial gas flow theory and law of conservation of energy. The key factors influencing the quantity of gas and the drainage flow network using a surface borehole were presented. The results show that the quantity of pressure-relieved gas drained from the protected layer can be significantly increased by increasing the flow resistance of the borehole bottom. Application of this method in the Wulan Coal Mine of the Shenhua Group significantly increased the flow of pure gas and the gas concentration (by factors of 1.8 and 2.0, respectively), thus demonstrating the remarkable effects of this method. 展开更多
关键词 Surface borehole Gas drainage Borehole bottom resistance Pressure-relieved gas
下载PDF
Determination of protection range of mining upper protective layers and its numerical simulation 被引量:1
7
作者 SONG Zhi-min GAO Xin-chun TIAN Kun-yun 《Journal of Coal Science & Engineering(China)》 2012年第4期368-373,共6页
Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward (including ... Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward (including the protection of working face layout and development direction), that is, gas flow observation analysis on the spot and gas content contrast method. The protection region was determined by gas flow observation analysis, gas content contrast, and computer numerical simulation combined with engineering practice. In the process of gas content test, the fixed sampling method "big hole drill reaming, small orifice drill rod connected with core tube" was employed. The results show that the determined protection region is in accordance with the actual site situation. The fixed sampling method ensures the accuracy of gas measurement of gas content. 展开更多
关键词 protective layer protection region numerical simulation fixed point sampling
下载PDF
Calorimetric Determination of Enthalpy of Formation of Natural Gas Hydrates 被引量:2
8
作者 高军 Kenneth N.Marsh 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2003年第3期276-279,共4页
This paper reports the measurements of enthalpies of natural gas hydrates in typical natural gas mixture containing methane, ethane, propane and iso-butane at pressure in the vicinity of 2000 kPa (300 psi) and 6900 kP... This paper reports the measurements of enthalpies of natural gas hydrates in typical natural gas mixture containing methane, ethane, propane and iso-butane at pressure in the vicinity of 2000 kPa (300 psi) and 6900 kPa(1000psi). The measurements were made in a multi-cell differential scanning calorimeter using modified high pressure cells. The enthalpy of water and the enthalpy of dissociation of the gas hydrate were determined from the calorimeter response during slow temperature scanning at constant pressure. The amount of gas released from the dissociation of hydrate was determined from the pumped volume of the high pressure pump. The occupation ratio (mole ratio) of the water to gas and the enthalpy of hydrate formation are subject to uncertainty of 1.5%.The results show that the enthalpy of hydrate formation and the occupation ratio are essentially independent of pressure. 展开更多
关键词 enthalpy of formation calorimetric determination natural gas hydrate
下载PDF
Improved Formula for Estimating Added Resistance of Ships in Engineering Applications 被引量:2
9
作者 Shukui Liu Baoguo Shang +1 位作者 Apostolos Papanikolaou Victor Bolbot 《Journal of Marine Science and Application》 CSCD 2016年第4期442-451,共10页
The authors previously introduced a semi-empirical formula that enabled fast estimation of the added resistance of ships in head waves, and in this study the formula is further refined for easy use in engineering appl... The authors previously introduced a semi-empirical formula that enabled fast estimation of the added resistance of ships in head waves, and in this study the formula is further refined for easy use in engineering applications. It includes an alternative ship draft correction coefficient, which better accounts for the wave pressure decay with ship’s draft. In addition, it only uses the speed and main characteristics of the ship and wave environment as input, and has been simplified to the extent that it can be readily processed using a pocket calculator. Extensive validations are conducted for different ship types at low to moderate speeds in various typical irregular sea conditions, and encouraging results are obtained. This relevant and topical research lies within the framework of the recent IMO MEPC.232(65) (2013) EEDI guidelines for estimating the minimum powering of ships in adverse weather conditions, which specify for the use of simple methods in current Level 2 assessment within engineering applications.Keywords: added resistance, minimum power, IMO regulation, EEDI regulation, weather coefficient, semi-empirical formulas, ships, head waves 展开更多
关键词 added resistance minimum power IMO regulation EEDI regulation weather coefficient semi-empirical formulas SHIPS head waves
下载PDF
^(13)C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations 被引量:1
10
作者 Anna Kasicka-Jonderko Anna Nita +2 位作者 Krzysztof Jonderko Magdalena Kamińska Barbara Bońska-Fajfrowska 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第45期4979-4986,共8页
AIM: To find the most reproducible quantitative parameter of a standard 13C-methacetin breath test (13C-MBT). METHODS: Twenty healthy volunteers (10 female, 10 male) underwent the 13C-MBT after intake of 75 mg 13C-met... AIM: To find the most reproducible quantitative parameter of a standard 13C-methacetin breath test (13C-MBT). METHODS: Twenty healthy volunteers (10 female, 10 male) underwent the 13C-MBT after intake of 75 mg 13C-methacetin p.o. on three occasions. Short-and medium-term reproducibility was assessed with paired examinations taken at an interval of 2 and 18 d (medians), respectively. RESULTS: The reproducibility of the 1-h cumulative 13C recovery (AUC0-60), characterized by a coefficient of variation of 10%, appeared to be considerably better than the reproducibility of the maximum momentary 13C recovery or the time of reaching it. Remarkably, as opposed to the short gap between consecutive examinations, the capacity of the liver to handle 13C-methacetin increased slightly but statistically significantly when a repeat dose was administered after two to three weeks.Regarding the AUC0-60, the magnitude of this fixed bias amounted to 7.5%. Neither the time gap between the repeat examinations nor the gender of the subjects affected the 13C-MBT reproducibility. CONCLUSION: 13C-MBT is most reproducibly quantified by the cumulative 13C recovery, but the exactitude thereof may be modestly affected by persistent stimulation of CYP1A2 on repeat examinations. 展开更多
关键词 13C-Methacetin Breath test Isotope application in medicine Liver REPRODUCIBILITY
下载PDF
Dynamic determination reserves of the underground gas storage
11
作者 谭羽非 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2004年第5期516-518,共3页
One of the key problems in the use of underground gas storage is frequent leakage. It can lead to the actual gas storage amount being less than that accounted for. Combining numerical simulation and parameter auto fit... One of the key problems in the use of underground gas storage is frequent leakage. It can lead to the actual gas storage amount being less than that accounted for. Combining numerical simulation and parameter auto fit, this paper ascertains the dynamic variation of the pressure in the storage reservoir, adjusts the actual injecting and producing gas to fit the accounted pressure with the tested pressure, obtains the gas leakage of the storage, and then determines the difference between accounted amount and leakage amount. The result is the actual reserves of the storage. The simulation result shows that the method presented can provide a theoretic foundation for estimating the leakage amount, thereby ensuring the actual reserves, searching the leakage route, and reducing leakage by adjusting the storage method. 展开更多
关键词 underground gas storage RESERVES fraction step solution numerical simulation parameter auto fit leakage problem
下载PDF
Time Series of Combustion Characteristics and Particulate Emission during Combustion of Thai Lignite in a Fixed Bed
12
作者 N. Mantananont S. Garivait S. Patumsawad 《Journal of Environmental Science and Engineering》 2011年第8期971-979,共9页
The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air (SA:TA) in a fixed bed combustor have been investigated in real-time. The results hav... The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air (SA:TA) in a fixed bed combustor have been investigated in real-time. The results have shown that particle formation is governed by competing reaction between the formation of the nucleated sized-particles (Dp 〈 0.1μm) and the coagulated particle (Dp 0.1-1 μm). Temperature and burning rate are the highest priority factors to control the emission of particulate. Furthermore, the co-firing of coal/rice husks at 60:40% mass fraction with 10%SA:TA could be the alternative options to further reduction of particulate and to be recommended. 展开更多
关键词 Combustion characteristics PARTICULATE Thai lignite COMBUSTION fixed bed.
下载PDF
Study on the concentrated SF_6 quantitative intelligent ultrasonic detection system 被引量:1
13
作者 朱昌平 Bian Mangxi +2 位作者 Shan Minglei Yin Dongmei Yu Hongzhen 《High Technology Letters》 EI CAS 2010年第4期378-382,共5页
In order to realize on-line quantitative detection on SF6 and effective control of nlnning state of SF6 high voltage power supply system, a concentrated SF6 quantitative ultrasonic on-line deteetion system has been de... In order to realize on-line quantitative detection on SF6 and effective control of nlnning state of SF6 high voltage power supply system, a concentrated SF6 quantitative ultrasonic on-line deteetion system has been developed based on the actual demand of electric power system consumers. There are four major characteristics in this system. Firstly, the gas of maximum 64 detection points is transferred through the specific air path to the detection devices to he detected and analyzed, thereby the electrical lines and the complicated installation of the collectors can be avoided; secondly, the differential technique is used to shield the influence of environmental factors, which effectively improves the accuracy of the acoustic detection; thirdly, the SF6 coneentration is determined by the speed and phase in the ultrasonic wave trans- mission process, therefore there is no secondary pollution for the purely physical means; finally, the ma- ture embedded technique is applied in this system to improve its intelligence and stability. 展开更多
关键词 ultrasonic detection concentrated SF6 embedded technique
下载PDF
Stable Isotopes in Precipitation and Atmospheric Moisture of Pailugou Catchment in Northwestern China′s Qilian Mountains 被引量:4
14
作者 FENG Fang FENG Qi +2 位作者 LIU Xiande WU Jinkui LIU Wei 《Chinese Geographical Science》 SCIE CSCD 2017年第1期97-109,共13页
Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δ^(18)O o... Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δ^(18)O of precipitation in continuous event-based samples at three stations of Pailugou Catchment from November 2012 to December 2013. The δ^(18)O and δD values ranged from-32.32‰ to +3.23‰ and from-254.46‰ to +12.11‰, respectively. Results show that the δ^(18)O displayed a distinct seasonal variation, with enriched values occurring in summer and relatively depleted values in winter, respectively. There was a statistically significant positive correlation between the δ^(18)O and δD values and local surface air temperature at all the three stations. The nearest Global Network of Isotopes in Precipitation(GNIP) station(Zhangye), compared to the Meteoric Water Lines for this study, showed the obvious local evaporation effects with lower intercept and slope. Additionally, d-excess(δD- 8δ^(18)O) parameter in precipitation exhibited an anti-phase seasonal variability with the δ^(18)O. The 96-h back trajectories for each precipitation event using Hybrid Single Particle Lagrangian Integrated Trajectory(HYSPLIT) model indicated a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter. 展开更多
关键词 meteoric precipitation δ^18O and δD d-excess moisture source Pailugou Catchment
下载PDF
Sensitivity of the Number of Snow Cover Days to Surface Air Temperature over the Qinghai-Tibetan Plateau 被引量:1
15
作者 Lijuan Ma Dahe Qin +2 位作者 Lingen Bian Cunde Xiao Yong Luo 《Advances in Climate Change Research》 SCIE 2010年第2期76-83,共8页
Based on the number of snow cover days (NSCDs) and homogenized surface air temperature data for the period 1951-2004, this study performs the quantitative analysis on the sensitivity of NSCDs to surface air temperat... Based on the number of snow cover days (NSCDs) and homogenized surface air temperature data for the period 1951-2004, this study performs the quantitative analysis on the sensitivity of NSCDs to surface air temperature over the Qinghai-Tibetan Plateau (QTP). Results show that both the extreme sensitivity and sensitivity under current climate are higher in the edge than in the central area of the QTP. There exists a strong negative correlation between station's elevation and critical temperature, at which the sensitivity reaches extremum. The negative correlation between the elevation and the extreme sensitivity is not as strong as the former one. Currently, the climatological temperatures in quite a few stations do not reach the critical stage. The sensitivity at these stations will become greater under the current background of climate warming, which means NSCDs will be more sensitive to surface air temperature. 展开更多
关键词 snow cover sensitivity Qinghai-Tibetan Plateau surface air temperature
下载PDF
Methane adsorption-induced coal swelling measured with an optical method 被引量:3
16
作者 Tang Shuheng Wan Yi +2 位作者 Duan Lijiang Xia Zhaohui Zhang Songhang 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2015年第6期949-953,共5页
In order to quantify the effect of matrix shrinkage on reservoir permeability during coalbed methane production, coal samples from Huozhou, Changzhi and Jincheng areas in Shanxi province (classified as high-volatile ... In order to quantify the effect of matrix shrinkage on reservoir permeability during coalbed methane production, coal samples from Huozhou, Changzhi and Jincheng areas in Shanxi province (classified as high-volatile bituminous coal, low-volatile bituminous coal and anthracite, respectively) were collected, and adsorption-induced coal swelling in methane were determined by an optical method at 40 ℃ and pressure up to 12 MPa. All three coals showed similar behavior-that swelling increased as a function of pressure up to about 10 MPa but thereafter no further increase in swelling was observed. Swelling in the direction perpendicular to the bedding plane is greater than that parallel to the bedding plane, and the differences are about 7.77-8.33%. The maximum volumetric swelling ranges from 2.73% to 3.21 %-increasing with increasing coal rank. The swelling data can be described by a modified DR model. In addition, swelling increases with the amount of adsorption. However, the increase shows a relatively slower stage followed by a relatively faster stage instead of a linear increase. Based on the assumption that sorption-induced swelling/shrinkage of coal in methane is reversible, the permeability increases induced by coal shrinkage during methane desorption was analyzed, and the results indicate that the permeability change is larger for higher rank coal in the same unit of pressure depletion. 展开更多
关键词 CoalAdsorptionMethaneSwellingPermeability
下载PDF
Recent Advances in Flame Tomography 被引量:5
17
作者 闫勇 邱天 +3 位作者 卢钢 M.M.Hossain G.Gilabert 刘石 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第2期389-399,共11页
To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed ... To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed combustion.Flame characteristics under such combustion conditions are expected to be different from those in normal air fired combustion processes.Quantified flame characteristics such as temperature distribution,oscillation frequency,and ignition volume play an important part in the optimized design and operation of the environmentally friendly power generation systems.However,it is challenging to obtain such flame characteristics particularly through a three-dimensional and non-intrusive means.Various tomography methods have been proposed to visualize and characterize flames,including passive optical tomography,laser based tomography,and electrical tomography.This paper identifies the challenges in flame tomography and reviews existing techniques for the quantitative characterization of flames.Future trends in flame tomography for industrial applications are discussed. 展开更多
关键词 power generation fossil fuel BIOMASS COMBUSTION FLAME tomography.imaging
下载PDF
Cave Environmental Changes: The Possibilities of Assessment
18
作者 Elena Trofimova 《Journal of Environmental Science and Engineering(B)》 2013年第11期640-642,共3页
The aim of this research is to apply a new approach to assess cave environmental changes--CDI (cave disturbance index), based on the five main categories: geomorphology, hydrology, atmosphere, biology and culture. ... The aim of this research is to apply a new approach to assess cave environmental changes--CDI (cave disturbance index), based on the five main categories: geomorphology, hydrology, atmosphere, biology and culture. The indicators of every category are considered in detail. The quantitative estimation of total CDI is proposed. 展开更多
关键词 Cave environmental changes ASSESSMENT CDI.
下载PDF
Storm in the Air: The Battle Over the 1992 Cable Act
19
作者 Samuel B. Hoff 《History Research》 2016年第3期121-133,共13页
Utilizing primary documents available at the George Bush Presidential Library, this study evaluates the veto record of President Bush using a case study as well as quantitative methods. The case study reviews the back... Utilizing primary documents available at the George Bush Presidential Library, this study evaluates the veto record of President Bush using a case study as well as quantitative methods. The case study reviews the background and fate of the only veto overridden during his term in office. It finds that the Bush White House had tried on several previous occasions to scrap the legislation, only to have it be reintroduced in each succeeding Congress. By 1992, when George Bush was running for reelection and in trouble politically, his team was unable to stave off defeat. The article likewise assesses the success of the Bush administration in its employment of the veto and compares the veto record of President Bush to previous and subsequent chief executives. 展开更多
关键词 VETO override PRESIDENT CONGRESS cable regulation 1992 Cable Act
下载PDF
Conformation and Orientation of Phospholipid Molecule in Pure Phospholipid Monolayer During Compressing
20
作者 XUE Weilan WANG Dan ZENG Zuoxiang GAO Xuechao 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第2期177-184,共8页
On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) in pure phospholipid rnono... On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) in pure phospholipid rnonolayer at the air/water interface during compression are derived. The optimized conformations of phospholipids at absolute freedom state are simulated by Gaussian 98 software. Based on following assumptions: (1) the conformation energy change is mainly caused by the rotation of one special bond; (2) the atoms of glycerol near the water surface are active; (3) the rotation is motivated by hydrogen-bond action; (4) the rotation of bond is inertial, one simplified track of conformational change is suggested and the conformations of DPPC and DPPG at different states are determined by the plots of conformation energy change vs. dihedral angle. The thickness of the simulated phospholipid monolayer is consistent with published experimental result. According to molecular areas at different states, the molecular orientations in the compressing process are also developed. 展开更多
关键词 DIPALMITOYLPHOSPHATIDYLCHOLINE dipalmitoylphosphatidylglycerol phospholipid monolayer CONFORMATION ORIENTATION
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部