Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172196
N. Babaeva, A. Mnatsakanyan, G. Naidis
Microwave discharges initiated at field intensities lower than threshold value for gas breakdown tend to propagate towards the source of electromagnetic radiation. The authors review the existing experimental data and the models of discharge propagation. The role of different mechanisms of propagation in various experimental conditions is discussed. Results of numerical modeling of discharge propagation in inert and molecular gases are presented. The model presented gives an approach to the description of the plane front propagation of nonequilibrium stimulated microwave discharge in inert and molecular gases.<>
{"title":"Breakdown and discharge propagation in microwave fields in inert and molecular gases","authors":"N. Babaeva, A. Mnatsakanyan, G. Naidis","doi":"10.1109/ICPADM.1991.172196","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172196","url":null,"abstract":"Microwave discharges initiated at field intensities lower than threshold value for gas breakdown tend to propagate towards the source of electromagnetic radiation. The authors review the existing experimental data and the models of discharge propagation. The role of different mechanisms of propagation in various experimental conditions is discussed. Results of numerical modeling of discharge propagation in inert and molecular gases are presented. The model presented gives an approach to the description of the plane front propagation of nonequilibrium stimulated microwave discharge in inert and molecular gases.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"60 1","pages":"832-835 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82953915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172280
N. Alame, G. Melik
An investigation of the external axial voltage and gradient distribution along the porcelain shells of metal oxide arresters was conducted. Various service conditions such as on ground or elevated installation, proximity to energized apparatus or large earthed objects, and their influence on the voltage and gradient distribution were studied. It was found that if an EHV arrester designed for on ground installation is erected on a tall slender pedestal, then the voltage gradient along its bottom section is greatly increased. If such an arrester is operating in a polluted environment the increase in voltage gradient in one location may cause external surface arcing and excessive voltage stresses on zinc-oxide blocks in that part of the arrester. Such a situation can be effectively improved by fitting a bottom grading ring, the shape of which can be determined through a modeling procedure. Both computer modeling and experimental techniques were used in the analysis and close agreement between the theoretical and experimental results was obtained. An innovative, fast, and simple method of measurement was developed and extensively tested on 500 kV surge arresters.<>
{"title":"Axial voltage and gradient distribution of metal oxide surge arresters","authors":"N. Alame, G. Melik","doi":"10.1109/ICPADM.1991.172280","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172280","url":null,"abstract":"An investigation of the external axial voltage and gradient distribution along the porcelain shells of metal oxide arresters was conducted. Various service conditions such as on ground or elevated installation, proximity to energized apparatus or large earthed objects, and their influence on the voltage and gradient distribution were studied. It was found that if an EHV arrester designed for on ground installation is erected on a tall slender pedestal, then the voltage gradient along its bottom section is greatly increased. If such an arrester is operating in a polluted environment the increase in voltage gradient in one location may cause external surface arcing and excessive voltage stresses on zinc-oxide blocks in that part of the arrester. Such a situation can be effectively improved by fitting a bottom grading ring, the shape of which can be determined through a modeling procedure. Both computer modeling and experimental techniques were used in the analysis and close agreement between the theoretical and experimental results was obtained. An innovative, fast, and simple method of measurement was developed and extensively tested on 500 kV surge arresters.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"24 1","pages":"1149-1151 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91177578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172239
Chang Xianmin, Wang Yougong, Liu Liqin, Song Lin
The authors report the thermal shrinkage test results on R-type polypropylene (PP) film exposed to atmosphere (non-impregnation) and immersed in dielectric liquid (impregnation). The results show that the sizes of machine and cross directions of PP film decrease with increasing temperature in two cases, and the thickness increases, but the starting temperatures bringing about the changes of the sizes are different. The results also show that the change of the thickness may be divided into three regions and is related to the change of the sizes of the machine and cross directions. The starting temperature bringing about the cross direction shrinkage is an important transition point in the change course of the thickness and an important index for selecting the technology temperature of PP film in a power capacitor.<>
{"title":"Research on drying and impregnating temperatures of PP film by the change of the sizes in thermal shrinkage test","authors":"Chang Xianmin, Wang Yougong, Liu Liqin, Song Lin","doi":"10.1109/ICPADM.1991.172239","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172239","url":null,"abstract":"The authors report the thermal shrinkage test results on R-type polypropylene (PP) film exposed to atmosphere (non-impregnation) and immersed in dielectric liquid (impregnation). The results show that the sizes of machine and cross directions of PP film decrease with increasing temperature in two cases, and the thickness increases, but the starting temperatures bringing about the changes of the sizes are different. The results also show that the change of the thickness may be divided into three regions and is related to the change of the sizes of the machine and cross directions. The starting temperature bringing about the cross direction shrinkage is an important transition point in the change course of the thickness and an important index for selecting the technology temperature of PP film in a power capacitor.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"43 1","pages":"992-994 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90270380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172246
K. Ohishi, T. Hirai, Y. Tanaka, Y. Ohki
The mechanism of electrical conduction in PEEK (polyether-ether-ketone) was studied from the results of DC conduction and thermal pulse current (TPC) measurements. The DC conduction current in PEEK films was measured at various electric fields at room temperature. From the results of electric-field dependence, it is thought that the conduction mechanism in PEEK is due to hopping. The TPC spectra, which were obtained under short-circuit conditions after the application of various voltages, show the existence of heterospace charges near the two electrodes. The TPC spectra increase with an increase in the electric field applied. From these results, it is thought that the electrical conduction in PEEK is due to carrier hopping. The carriers reached near the counterelectrode are not easily neutralized and begin to form heterocharges.<>
{"title":"High field properties of polyether-ether-ketone","authors":"K. Ohishi, T. Hirai, Y. Tanaka, Y. Ohki","doi":"10.1109/ICPADM.1991.172246","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172246","url":null,"abstract":"The mechanism of electrical conduction in PEEK (polyether-ether-ketone) was studied from the results of DC conduction and thermal pulse current (TPC) measurements. The DC conduction current in PEEK films was measured at various electric fields at room temperature. From the results of electric-field dependence, it is thought that the conduction mechanism in PEEK is due to hopping. The TPC spectra, which were obtained under short-circuit conditions after the application of various voltages, show the existence of heterospace charges near the two electrodes. The TPC spectra increase with an increase in the electric field applied. From these results, it is thought that the electrical conduction in PEEK is due to carrier hopping. The carriers reached near the counterelectrode are not easily neutralized and begin to form heterocharges.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"22 1","pages":"1018-1020 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85094927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172015
S. Maeta, H. Suzuki, F. Yoshida
Important concepts in the promotion of TSC (thermally stimulated current) research are described, and the distribution law of carrier-trap states is reported. The concept of organization is established upon the basis of the concept of the 'fundamental element'. The concept utilized to organize the fundament elements originally, the concept used to stabilize the organized elements, and the concept of 'purification' are key in the evaluation of the exact TSC parameters. They make possible the perfect autoseparation of the composite TSC curve into single curves. Moreover, the concept of purification is an indispensable method for determining sufficient figures for discussing the main subject. The method established from the concept of 'purity' by which one can calculate the TSC curve without any ambiguities supports these perfect autoseparation processes. Upon the 'organized ground' established by these concepts, the distribution law of carrier-trap states in organic materials is revealed and discussed.<>
{"title":"The electrical conduction processes in organic materials considered by a new concept of the thermally stimulated current","authors":"S. Maeta, H. Suzuki, F. Yoshida","doi":"10.1109/ICPADM.1991.172015","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172015","url":null,"abstract":"Important concepts in the promotion of TSC (thermally stimulated current) research are described, and the distribution law of carrier-trap states is reported. The concept of organization is established upon the basis of the concept of the 'fundamental element'. The concept utilized to organize the fundament elements originally, the concept used to stabilize the organized elements, and the concept of 'purification' are key in the evaluation of the exact TSC parameters. They make possible the perfect autoseparation of the composite TSC curve into single curves. Moreover, the concept of purification is an indispensable method for determining sufficient figures for discussing the main subject. The method established from the concept of 'purity' by which one can calculate the TSC curve without any ambiguities supports these perfect autoseparation processes. Upon the 'organized ground' established by these concepts, the distribution law of carrier-trap states in organic materials is revealed and discussed.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"11 1","pages":"97-100 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85165105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172161
K. Kurahashi, K. Asari, K. Yatsuka, M. Watanabe, K. Kishi, H. Inoue
Since dielectric breakdown failures have sometimes occurred in XLPE (cross-linked polyethylene) cable facilities, the development of a failure prediction method is strongly desirable so that such failures during power transmission can be prevented in advance. As a result of failure analysis of 77 kV class XLPE cables, it has been found that most of such dielectric breakdowns in power transmission lines have occurred in the accessories, caused by defective execution. The authors have succeeded in developing a method to detect partial discharge occurring before the accessories generate such dielectric breakdown. They describe this method, and report on a study to apply it to failure prediction technology. The authors constructed a line incorporating various types of accessories and evaluated the possibility of detecting such partial discharges to determine the practical feasibility of the proposed method. As a result, it was ascertained that one can detect a partial discharge in the case of every accessory investigated in the present study.<>
{"title":"Development of failure prediction method for accessories of XLPE cable lines","authors":"K. Kurahashi, K. Asari, K. Yatsuka, M. Watanabe, K. Kishi, H. Inoue","doi":"10.1109/ICPADM.1991.172161","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172161","url":null,"abstract":"Since dielectric breakdown failures have sometimes occurred in XLPE (cross-linked polyethylene) cable facilities, the development of a failure prediction method is strongly desirable so that such failures during power transmission can be prevented in advance. As a result of failure analysis of 77 kV class XLPE cables, it has been found that most of such dielectric breakdowns in power transmission lines have occurred in the accessories, caused by defective execution. The authors have succeeded in developing a method to detect partial discharge occurring before the accessories generate such dielectric breakdown. They describe this method, and report on a study to apply it to failure prediction technology. The authors constructed a line incorporating various types of accessories and evaluated the possibility of detecting such partial discharges to determine the practical feasibility of the proposed method. As a result, it was ascertained that one can detect a partial discharge in the case of every accessory investigated in the present study.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"72 1","pages":"699-702 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84496142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172040
T. Kawashima, T. Maki, T. Takahashi, K. Maeda
Water-tree-retardant XLPE was evaluated using two types of polyethylene: a polymer-blend XLPE containing blends of ethylene copolymer having a polar group, and VLDPE (very low density polyethylene), which is a novel grade of polyethylene. While the polymer blend XLPE permitted cable extrusion under the same conditions as in the case of conventional XLPE because its base material is conventional XLPE, the VLDPE was so difficult to extrude that the extruding conditions had to be modified. The water-tree acceleration test (10 kV, 1 kHz, conductor and inside of jacket poured with water, 90 degrees C heat cycle) using the cable samples (insulation thickness of 3 mm) demonstrated a water-tree retardant effect in favor of the polymer blend XLPE, that is, about 1/30 of the water-tree (bow-tie tree) generation and 1/2 of the maximum length of the water tree as compared with conventional XLPE. Furthermore, the test revealed no generation of bow-tie trees in the VLDPE, demonstrating an almost complete water-tree retardant effect.<>
{"title":"Study on water treeing retardant XLPE insulations","authors":"T. Kawashima, T. Maki, T. Takahashi, K. Maeda","doi":"10.1109/ICPADM.1991.172040","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172040","url":null,"abstract":"Water-tree-retardant XLPE was evaluated using two types of polyethylene: a polymer-blend XLPE containing blends of ethylene copolymer having a polar group, and VLDPE (very low density polyethylene), which is a novel grade of polyethylene. While the polymer blend XLPE permitted cable extrusion under the same conditions as in the case of conventional XLPE because its base material is conventional XLPE, the VLDPE was so difficult to extrude that the extruding conditions had to be modified. The water-tree acceleration test (10 kV, 1 kHz, conductor and inside of jacket poured with water, 90 degrees C heat cycle) using the cable samples (insulation thickness of 3 mm) demonstrated a water-tree retardant effect in favor of the polymer blend XLPE, that is, about 1/30 of the water-tree (bow-tie tree) generation and 1/2 of the maximum length of the water tree as compared with conventional XLPE. Furthermore, the test revealed no generation of bow-tie trees in the VLDPE, demonstrating an almost complete water-tree retardant effect.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"10 1","pages":"222-225 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84529976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172138
M. Nawata, H. Kawamura, I. Ishino, M. Ieda
Electrical- and water-treeing breakdown phenomena were investigated on polyethylene copolymerized with various monomers. The resistance to electrical treeing in copolymerized specimens was evaluated according to the tree-inception voltages. The AC-tree-inception voltage decreased with increase in halogen atom content in the monomers. The resistance to water treeing in copolymerized specimens was evaluated according to the growth of water trees that arose from the tip of a needle-like water electrode. The growth of water treeing decreased with increase in halogen atom content in the monomers. Halogen atoms which were copolymerized in polyethylene improved the AC-electric-tree resistance and the water-tree resistance.<>
{"title":"Effect of copolymerization on electrical and water trees of polyethylene","authors":"M. Nawata, H. Kawamura, I. Ishino, M. Ieda","doi":"10.1109/ICPADM.1991.172138","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172138","url":null,"abstract":"Electrical- and water-treeing breakdown phenomena were investigated on polyethylene copolymerized with various monomers. The resistance to electrical treeing in copolymerized specimens was evaluated according to the tree-inception voltages. The AC-tree-inception voltage decreased with increase in halogen atom content in the monomers. The resistance to water treeing in copolymerized specimens was evaluated according to the growth of water trees that arose from the tip of a needle-like water electrode. The growth of water treeing decreased with increase in halogen atom content in the monomers. Halogen atoms which were copolymerized in polyethylene improved the AC-electric-tree resistance and the water-tree resistance.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"60 1","pages":"143-146 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83416246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172054
J. Sletbak
The author outlines the mechanical damage theory and the electrochemical theory of water treeing. A selection of experimental results is then reviewed, mainly based on work done in the author's laboratory to examine the validity of the mechanical damage theory. It is noted that, even though no single experiment can prove or disprove this theory, many experiments have led to results which are in agreement with it. This is particularly true for the initiation of water trees. It is possible that chemical or electrochemical reactions play a more important role in the growth phase, mainly because of their influence on the hydrophobicity and the mechanical properties of the material.<>
{"title":"The mechanical damage theory of water treeing-a status report","authors":"J. Sletbak","doi":"10.1109/ICPADM.1991.172054","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172054","url":null,"abstract":"The author outlines the mechanical damage theory and the electrochemical theory of water treeing. A selection of experimental results is then reviewed, mainly based on work done in the author's laboratory to examine the validity of the mechanical damage theory. It is noted that, even though no single experiment can prove or disprove this theory, many experiments have led to results which are in agreement with it. This is particularly true for the initiation of water trees. It is possible that chemical or electrochemical reactions play a more important role in the growth phase, mainly because of their influence on the hydrophobicity and the mechanical properties of the material.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"47 1","pages":"208-213 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87000704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172076
K. Tsuruta, H. Ebara
A gas temperature decay model has been developed assuming that the recovering hot gas is a spherical lump and its temperature is uniform throughout the recovery. The calculation of the temperature decay by this model consists of the calculation of the time constants of the decay process of the recovering hot gas as a function of the size of the spherical gas lump and gas temperature. Calculated temperature decay characteristics almost agree with those obtained from experimental voltage-recovery characteristics.<>
{"title":"A model of gas temperature decay after arc extinction of small air gaps","authors":"K. Tsuruta, H. Ebara","doi":"10.1109/ICPADM.1991.172076","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172076","url":null,"abstract":"A gas temperature decay model has been developed assuming that the recovering hot gas is a spherical lump and its temperature is uniform throughout the recovery. The calculation of the temperature decay by this model consists of the calculation of the time constants of the decay process of the recovering hot gas as a function of the size of the spherical gas lump and gas temperature. Calculated temperature decay characteristics almost agree with those obtained from experimental voltage-recovery characteristics.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"11 1","pages":"377-380 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88294064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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