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Quantitative Analysis of the Fatty Acid Compositions of Different Oils and Associations with Antioxidant Capacity and Oxidative Stability 被引量:1
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作者 LIU Junchen SUN Xiaoman +3 位作者 ZHANG Huirong SHAO Haofan LING Xiao LI Li 《现代食品科技》 北大核心 2025年第4期305-315,共11页
Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships w... Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils. 展开更多
关键词 gas chromatography-mass spectrometry vegetable oil fatty acid composition oxidative stability antioxidant capacity
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REMARKS ON ASYMPTOTIC EXPANSIONS OF COMPOSITIONS WITH THE ELEMENTARY FUNCTIONS
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作者 LUO Xiao-Yu SHI Yong-Guo JIANG Zhi-Jie 《数学杂志》 2025年第2期131-139,共9页
In this paper,we study asymptotic power series of the composition f(x)=h(g(x)),where g(x)=∑_(n=0)^(∞)b_(n)x^(-n),b_(n)∈R,and h is a given elementary function.The asymptotic expansions have been obtained for the com... In this paper,we study asymptotic power series of the composition f(x)=h(g(x)),where g(x)=∑_(n=0)^(∞)b_(n)x^(-n),b_(n)∈R,and h is a given elementary function.The asymptotic expansions have been obtained for the composition with an exponential or logarithmic function.Using the re-cursive method,we present the asymptotic expansions for the composition with seven trigonometric functions,respectively.As an application,the asymptotic expansions of roots of some equations are given.Computational results show that our recursive formula is more efficient than the method of Lagrange's inverse theorem. 展开更多
关键词 asymptotic expansion asymptotic power series trigonometric function composite function
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Some Notes on Inplace Identities for Compositions 被引量:3
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作者 Yuhong GUO 《Journal of Mathematical Research with Applications》 CSCD 2016年第5期515-520,共6页
In this paper we give combinatorial proofs of two recurrence relations for the special class of objects known as inplace compositions. We also obtain new identities for the numbers of inplace 1-2 compositions and pali... In this paper we give combinatorial proofs of two recurrence relations for the special class of objects known as inplace compositions. We also obtain new identities for the numbers of inplace 1-2 compositions and palindromic compositions. 展开更多
关键词 compositions 1-2 compositions palindromic compositions inplace IDENTITY combinatorial proof
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Effects of light spectra on growth and compositions of biomass,fatty acids,and pigments in three typical microalgae from different phyla
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作者 Fei KONG Jiaxing ZHANG +6 位作者 Dongzi YANG Yao ZHOU Yanrong LI Deshui CHEN Xiaojun YAN Zhaoshou RAN Jilin XU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第6期1976-1990,共15页
The growth and nutrients of photosynthetic organisms are significantly influenced by light spectra,yet this relationship is not well-understood in microalgae.Herein,we studied three microalgae species—Chaetoceros sp.... The growth and nutrients of photosynthetic organisms are significantly influenced by light spectra,yet this relationship is not well-understood in microalgae.Herein,we studied three microalgae species—Chaetoceros sp.,Isochrysis galbana,and Tetraselmis helgolandica—distinguished by their pigments.We exposed them to seven light spectra,including white(control),red,orange,green,blue,violet,and full spectrum.The results showed distinct responses in the three microalgae to varying light spectra.Optimal growth occurred under blue,violet,and white lights for Chaetoceros sp.,Ⅰ.galbana,and T.helgolandica,respectively,while orange,red,and green lights inhibited growth.Notably,green light significantly increased the protein content in all three microalgae.Carbohydrate and lipid content exhibited species-specific responses:the highest carbohydrate accumulation was achieved for Chaetoceros sp.under red light(73.27±1.45 mg/g),Ⅰ.galbana under orange light(122.89±12.28 mg/g),and T.helgolandica under blue light(43.62±2.79 mg/g).Meanwhile,the highest lipid content was obtained under violet light for Chaetoceros sp.andⅠ.galbana(250.80±7.27 and 320.23±5.75 mg/g,respectively),and under green light for T.helgolandica(255.12±31.19 mg/g).Furthermore,violet light greatly promoted the accumulation of polyunsaturated fatty acids in all three microalgae.Specific pigment compositions also responded to variations in light spectra.For instance,the diadinoxanthin content in Chaetoceros sp.increased significantly under orange light(194.77±13.78μg/g),while chlorophyll-a content inⅠ.galbana increased significantly under violet and blue lights((88.84±33.46)-(141.38±1.64)μg/g),and in T.helgolandica under red,green,and blue lights((1485.04±190.46)-(1886.60±387.42)μg/g).Additionally,Ⅰ.galbana exhibited the highest fucoxanthin,diadinoxanthin,andβ-carotene contents under white light.In conclusion,our results highlight the species-specific impact of light spectra on microalgae growth and nutrients,providing valuable guidance for flexible application of light spectra in microalgal production to enhance yields and target specific nutrients. 展开更多
关键词 MICROALGAE light spectrum GROWTH biomass composition fatty acids PIGMENT
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Exploring Nutritional Compositions,Volatile Compounds,Health Benefits,Emerging Processing Technologies,and Potential Food Products of Glutinous Rice:A Review
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作者 Maimunah Mohd ALI Norhashila HASHIM 《Rice science》 SCIE CSCD 2024年第3期251-268,共18页
Glutinous rice(Oryza sativa var.glutinosa)stands out as one of the most popular rice varieties globally,amidst thousands of rice cultivars.Its increasing popularity is attributed to its rich nutritional compositions a... Glutinous rice(Oryza sativa var.glutinosa)stands out as one of the most popular rice varieties globally,amidst thousands of rice cultivars.Its increasing popularity is attributed to its rich nutritional compositions and health benefits.This review aims to summarize the nutritional compositions,volatile compounds,and health benefits of glutinous rice.Further,in-depth studies are necessary to explore the utilization of glutinous rice in enhancing processing technologies and developing new food products.Glutinous rice has been shown to possess numerous health benefits,including antioxidant activity,bioactive compounds,anti-cancer properties,anti-inflammatory effects,anti-diabetic potential,and cholesterol-lowering effects.Besides its nutritional compositions,the major volatile compounds identified in glutinous rice could serve as a functional food for human consumption.Emerging processing technologies related to glutinous rice are elaborated to improve the latest developments for incorporating them into various food products. 展开更多
关键词 glutinous rice health benefit volatile compound nutritional composition processing technology
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Chemical Compositions of Volatile Oil from Fruiting Body of Armillaria luteo-virens 被引量:30
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作者 周劲松 熊辉岩 +2 位作者 杨春江 焦迎春 盛海彦 《Agricultural Science & Technology》 CAS 2008年第2期90-92,共3页
The chemical compositions of volatile oil from fruiting body of Armillaria luteo-virens in Qinghai Province were firstly analyzed with GC-MS and its relevant compositions were detected by calculating chromatographic p... The chemical compositions of volatile oil from fruiting body of Armillaria luteo-virens in Qinghai Province were firstly analyzed with GC-MS and its relevant compositions were detected by calculating chromatographic peak area with normalized method. 21 peaks were separated and 13 compositions were identified which were mainly unsaturated fatty acids, taking 97.1% of the total volatile oil. 展开更多
关键词 Armillaria luteo-rirens Volatile oil Chemical compositions GC-MS
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Functional evaluation for effective compositions in seed oil of Korean pine 被引量:14
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作者 王振宇 陈小强 《Journal of Forestry Research》 SCIE CAS CSCD 2004年第3期215-217,共3页
The effect of seed oil of Korean pine (Pinus koraiensis) on the rats' blood-fat and its anti-ageing function was stud-ied for appraising the efficacy of the seed oil of Korean pine. Sixty experimental rats were ra... The effect of seed oil of Korean pine (Pinus koraiensis) on the rats' blood-fat and its anti-ageing function was stud-ied for appraising the efficacy of the seed oil of Korean pine. Sixty experimental rats were randomly divided into 5 groups (half males and half females in each group) as normal control group, high fat diet control group, and three groups (Group 1 Group 2, Group 3) that were fed with feedstuff with the contents of the seed oil of 2.0g/(kgd-1), 4.0g/(kgd-1) and 8.0g/(kgd-1), respec-tively. The indexes such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and anti-oxidation capacity (AOC) were measured by Reagent Kit method. It was found that the seed oil of the Korean pine could reduce the content of triglyc-eride and improve SOD as well as GSH-PX activity in serum. These indexes of the rats in Group 2 fed with Korean pine seed oil of 4.0 g/(kgd-1) reached the significant level and those of rats in Group 3 fed with the seed oil of 8.0 g/(kgd-1) reached the extremely significant level. The results indicated the seed oil of Korean pine had function of regulating the level of blood-fat and anti-ageing. 展开更多
关键词 Korean pine seed oil Effective compositions Functional evaluation Blood-fat ANTI-AGEING
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Chemical compositions and pharmacological activities ofXanthium strumarium
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作者 Ruoming Li Yunpeng Yan +4 位作者 Xiaomeng Zhangc Yibo Wang Wenhan Wang Yao Zhao Yu Chen 《Asian Journal of Traditional Medicines》 2024年第6期342-352,共11页
Xanthium strumarium(X.strumarium)is a traditional Chinese medicine with a long history.In recent years,with the development of modern pharmacology and chemical analysis technology,research on X.strumarium has been dee... Xanthium strumarium(X.strumarium)is a traditional Chinese medicine with a long history.In recent years,with the development of modern pharmacology and chemical analysis technology,research on X.strumarium has been deepend.This paper aims to systematically summarize the chemical compositions and pharmacological effects of X.strumarium,in order to provide theoretical basis and reference for further exploration in its clinical application and drug development. 展开更多
关键词 Xanthium strumarium chemical composition pharmacological activities
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Nutritional Compositions of Maca Grown in Ebian and HPLC Fingerprints of Macaene and Macamide 被引量:2
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作者 陈建 夏陈 +1 位作者 朱永清 栢凤女 《Agricultural Science & Technology》 CAS 2016年第4期947-950,共4页
In the present study, the nutritional compositions of maca which was grown in a mountain area at an elevation of 2 200-2 800 m of Ebian County,Sichuan Province were measured, and then HPLC analysis on two representati... In the present study, the nutritional compositions of maca which was grown in a mountain area at an elevation of 2 200-2 800 m of Ebian County,Sichuan Province were measured, and then HPLC analysis on two representative active compounds(macaene and macamide) in the maca sample was performed.The results revealed that there were 24.20% total protein, 18.40% total amino acids(including 3.84% arginine), 42.80% total sugars, 1.36% fat and kinds of minerals(including 1.14% potassium) in Ebian maca. HPLC fingerprints of macaene and macamide of Ebian maca were similar to those of Peru maca. The results suggested that maca could be cultivated with good quality in some mountain areas with an altitude1 000 m lower than the origin place in Peru. 展开更多
关键词 MACA Nutritional compositions Macaene Macamide HPLC fingerprints
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Research on Nourishing Compositions of Fagopyrum tataricum 被引量:2
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作者 宋毓雪 黄凯丰 《Agricultural Science & Technology》 CAS 2010年第9期115-117,共3页
[Objective] The aim was to identify the nourishing compositions of Fagopyrum tataricum and screen high-quality buckwheat materials.[Method]A total of 10 species of buckwheat including T32,T31,T30,T14,T28,T23,T24,Jiuji... [Objective] The aim was to identify the nourishing compositions of Fagopyrum tataricum and screen high-quality buckwheat materials.[Method]A total of 10 species of buckwheat including T32,T31,T30,T14,T28,T23,T24,Jiujiang Buckwheat,Weiku 2 and WK-1 were employed as experimental materials,and the contents of the nutritional components(including total sugar,reducing sugar,starch,amylose,amylopectin and protein),flavonoids content,physical and chemical characteristics(such as expansive force,water holding capacity)of them were respectively measured.[Result]There were significant differences in contents of soluble protein,total sugar,reduced sugar,amylase and expansive force among the cultivars,but the differences in contents of total starch,amylopectin,flavonoids content and water holding capacity were not significant.[Conclusion]The starch content in seeds of buckwheat was relatively high,and amylopectin was the main composition. 展开更多
关键词 BUCKWHEAT Nourishing compositions Physical and chemical characteristics
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Inheritance of Fat and Fatty Acid Compositions in Peanut (Arachis hypogaea L.) 被引量:6
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作者 张新友 祝水金 +6 位作者 韩锁义 徐静 刘华 汤丰收 董文召 臧秀旺 张忠信 《Agricultural Science & Technology》 CAS 2011年第7期943-946,974,共5页
[Objective] The aim was to explore the inheritance of fat and fatty acid compositions in peanut.[Method] Genetic and correlation analyses were performed using a mixed genetic model of major gene plus polygene with 215... [Objective] The aim was to explore the inheritance of fat and fatty acid compositions in peanut.[Method] Genetic and correlation analyses were performed using a mixed genetic model of major gene plus polygene with 215 F9 RILs and their parents ZHENG 8903 and YUHUA No.4.[Result] The optimal genetic model of the fat content was two linked complementary major gene plus polygene inheritance model.The heritability of major genes was 22.88%.Oleic,linoleic,and palmitic acid content were controlled by two major genes and the heritability was 75.11%,75.00% and 60.95%,respectively.Stearic and arachidic acid content were controlled by two major genes plus polygenes,the heritability of major genes was 26.43% and 33.17%,respectively.O/L ratio and behenic acid content were controlled by three major genes,the heritability was 70.65% and 30.70%,respectively.[Conclusion] The result in this study was that accumulating polygenes should be emphasized in the improvement of fat content,while utilization of major genes is enhanced in improvement of oleic and linoleic acids. 展开更多
关键词 PEANUT FAT Fatty acid composition INHERITANCE
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Aerosol scattering coefficients and major chemical compositions of fine particles observed at a rural site in the central Pearl River Delta,South China 被引量:25
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作者 Xinming Wang Xiang Ding +5 位作者 Xiaoxin Fu Quanfu He Shaoyi Wang Francois Bernard Xiuying Zhao Dui Wu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第1期72-77,共6页
During November–December 2010 aerosol scattering coefficients were monitored using a single-waved (525 nm) Nephelometer at a regional monitoring station in the central Pearl River Delta region and 24-hr fine partic... During November–December 2010 aerosol scattering coefficients were monitored using a single-waved (525 nm) Nephelometer at a regional monitoring station in the central Pearl River Delta region and 24-hr fine particle (PM 2.5) samples were also collected during the period using quartz filters for the analysis of major chemical components including organic carbon (OC),elemental carbon (EC),sulfate,nitrate and ammonium.In average,these five components accounted for about 85% of PM 2.5 mass and contributed 42% (OC),19% (SO 4 2 -),12% (NO 3 -),8.4% (NH 4+) and 3.7% (EC),to PM 2.5 mass.A relatively higher mass scattering efficiency of 5.3 m 2/g was obtained for fine particles based on the linear regression between scattering coefficients and PM 2.5 mass concentrations.Chemical extinction budget based on IMPROVE approach revealed that ammonium sulfate,particulate organic matter,ammonium nitrate and EC in average contributed about 32%,28%,20% and 6% to the light extinction coefficients,respectively. 展开更多
关键词 scattering coefficients VISIBILITY fine particle (PM 2.5) chemical compositions
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Advances in Research on Triterpenoids and Volatile Compositions of Kudingcha
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作者 杨刚劲 黄艳 +2 位作者 郑金燕 赖茂祥 刘布鸣 《Agricultural Science & Technology》 CAS 2014年第6期1012-1014,共3页
Kudingcha, a commonly used traditional Chinese medicine, has multiple functions in anti-radiation, anti-aging, quickening the blood vessels, reducing blood lipid and blood pressure and so forth. Therefore, this articl... Kudingcha, a commonly used traditional Chinese medicine, has multiple functions in anti-radiation, anti-aging, quickening the blood vessels, reducing blood lipid and blood pressure and so forth. Therefore, this article reviews the origins of Kudingcha, and analyzes the major triterpenoids and volatile chemicals, with an at- tempt to provide more references for the development and utilization of Kudingcha. 展开更多
关键词 KUDINGCHA ORIGIN TRITERPENOIDS VOLATILE Chemical compositions
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Study on Main Chemical Compositions of Rice Straw in Three Different Areas of Jiangsu Province 被引量:1
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作者 宋卫东 王教领 +3 位作者 王明友 吴今姬 李尚昆 王培雨 《Agricultural Science & Technology》 CAS 2016年第2期405-408,共4页
[Objective] The research was aimed to study the main chemical composi- tions of rice straw in the three different areas of Jiangsu Province. [Method] The cellulose, hemicellulose, lignin and crude ash of rice straw co... [Objective] The research was aimed to study the main chemical composi- tions of rice straw in the three different areas of Jiangsu Province. [Method] The cellulose, hemicellulose, lignin and crude ash of rice straw collected in Huaian, Changzhou and Zhenjiang of Jiangsu Province during 2011-2013 were determined. [Result] The change trends of cellulose and hemicellulose in three arrears in differ- ent years were consistent. The cellulose content increased after falling, and hemi- cellulose content presented declining tendency. The lignin content of rice straw fist rose then declined in Huaian and Changzhou in different years, while it presented the declining tendency in Zhenjiang. The ash content of rice straw changed little and was all less than 65% in the three areas in different years. And the chemical composition of rice straw changed significantly in different years. [Conclusion] The research could provide basis for high added-value use of crop straw. 展开更多
关键词 Rice straw Different years Chemical composition Jiangsu Province
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Comparison on the Chemical Compositions in the K326 Tobacco from Different Tobacco-planting Areas of Yunnan Province 被引量:12
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作者 王岚 杨继周 +8 位作者 蒋美红 段俊杰 卢叶 敖金成 马彦清 李继飞 王涛 林楠 邓国宾 《Agricultural Science & Technology》 CAS 2012年第1期139-142,共4页
[Objective] To compare the regional differences of the conventional chemi- cal compositions in the K326 B2F tobacco from different tobacco-planting areas of Yunnan Province. [Methed] Continuous flow analyzer was used ... [Objective] To compare the regional differences of the conventional chemi- cal compositions in the K326 B2F tobacco from different tobacco-planting areas of Yunnan Province. [Methed] Continuous flow analyzer was used to detect the con- ventional chemical compositions, and SPSS 17.0 statistical package was used to conduct data statistical analysis and variance analysis. [Result] Significant differences were existed among most of the indicators for conventional chemical compositions of K326 tobacco in different areas: the differences of total sugar, reducing sugar and nicotine reached a high Significant level; potassium ion and total nitrogen differences reached a significant level, while there was no significant difference in chlorine ion. Most of the conventional chemical compositions in K326 B2F tabacco planted in Yuxi region and those planted in Qujing, Dali and Chuxiong were significantly different. The total sugar, reducing sugar and nicotine contents of tobacco planted in eastern Yunnan, central Yunnan and western Yunnan were significantly different; while the conventional chemical compositions contents in the tobacco planted in Chuxiong and Dali, which all belong to western Yunnan, showed no obvious significant difference, indicating different ecological environments in large area had a great impact on the tobacco of Yunnan Province. [Conclusion] It revealed the regional characteristics of the conventional chemical compositions in K326 flue-cured tobacco leaves from Yunnan Province, providing references for the cigarette blending and production of high-quality tobacco with characteristics. 展开更多
关键词 K326 B2F Conventional chemical compositions DIFFERENCE
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Petrogenesis and Tectonic Significance of the Xiuwacu Two-Period Magmatism in Geza Arc of Yunnan Province: Constraints from Lithogeochemistry, Zircon U-Pb Geochronology and Hf isotopic Compositions 被引量:6
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作者 LAI Anqi LI Zhe +1 位作者 LIU Xuelong LI Yang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第2期757-758,共2页
Objective The Late Cretaceous Xiuwacu ore-bearing porphyry is located in the Geza area of southern Yidun arc, SW China. In this area, the rock mass is mainly composed of three lithofacies: biotite granite porphyry, ... Objective The Late Cretaceous Xiuwacu ore-bearing porphyry is located in the Geza area of southern Yidun arc, SW China. In this area, the rock mass is mainly composed of three lithofacies: biotite granite porphyry, monzonitic granite and light alkali feldspar granite. As a part of the Yidun arc, the Geza arc has common structure and temporal- spatial evolution with the ~idun arc, which has experienced three stages of oceanic crust subduction, collision orogeny and intracontinent convergence stages. The molybdenite ores in the area are mainly hosted in monzonitic granite-porphyry and structural fracture zone, and the ore bodies are strictly controlled by faults. In recent years, great geological prospecting results have been achieved in Xiuwacu, and the deposit has reached a medium scale. However, there are few researches on the metallogenic porphyry. Based on the previous research, we determined the rock-forming and ore-forming age of the porphyry, and found that there were two stages of magmatism intrusion in Xiuwacu: Indosinian and Yanshanian. We also discussed the geochemical characteristics and source area of the rocks in the area. 展开更多
关键词 Hf Constraints from Lithogeochemistry Petrogenesis and Tectonic Significance of the Xiuwacu Two-Period Magmatism in Geza Arc of Yunnan Province Zircon U-Pb Geochronology and Hf isotopic compositions Pb
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Effects of Mg/PTFE pyrotechnic compositions on reignition characteristics of base bleed propellants and heating mechanism 被引量:4
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作者 Xiao-chun Xue Long-ze Ma Yong-gang Yu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第1期94-108,共15页
The effects of magnesium/polytetrafluoroethylene(Mg/PTFE)pyrotechnic compositions on the coupled flow field and reignition mechanism are important aspects governing the perfommance and range of base bleed projectiles(... The effects of magnesium/polytetrafluoroethylene(Mg/PTFE)pyrotechnic compositions on the coupled flow field and reignition mechanism are important aspects governing the perfommance and range of base bleed projectiles(BBPs).Owing to a decrease in pressure and temperature when the BBP leaves the muzzle,rapid depressurization occurs,which extinguishes the base bleed propellant.The Mg/PTFE py-rotechnic composition pressed in the igniter of the base bleed unit(BBU)provides additional energy to the BBU via a chemical reaction.Thus,the extinguished base bleed propellant is reignited under the effect of high-temperature combustion gas jets from the igniter.In this study,a numerical analysis is conducted to evaluate the effects of PTFE and Mg granularity as well as Mg/PTFE pyrotechnic compo-sitions.Owing to the rapid depressurization,the temperature and pressure was found to decrease fordifferent Mg/PIFE pyrotechnic compositions.However,the depressurization time increased as the PTFE granularity increased,the Mg granularity decreased,and the Mg content increased.When the pressure in the combustion chamber of the BBU decreased to the atmospheric pressure,the combustion gas jets from the igniter expand upstream(rather than downstream).However,these combustion gas jets exhibit different axial and radial expansion characteristics depending on the pyrotechnic compositions used,The results show that the reignition delay time,ta,of the base bleed propellant was 377.608,94.27,387.243,523.966,and 221.094 ms for cases A-E,respectively.Therefore,it was concluded that the Mg/PTFE pyrotechnic composition of case B was the most beneficial for the reignition of the base bleed propellant,with the earliest addition of energy and mass to the BBP. 展开更多
关键词 Thermal effect High-temperature combustion gas Mg/PTFE pyrotechnic compositions REIGNITION
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Influence of contamination on banded iron formations in the Isua supracrustal belt, West Greenland: Reevaluation of the Eoarchean seawater compositions 被引量:3
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作者 Shogo Aoki Chiho Kabashima +2 位作者 Yasuhiro Kato Takafumi Hirata Tsuyoshi Komiya 《Geoscience Frontiers》 SCIE CAS CSCD 2018年第4期1049-1072,共24页
Banded Iron Formations(BIFs) are chemical sediments, ubiquitously distributed in the Precambrian supracrustal belts; thus their trace element compositions are helpful for deciphering geochemical evolution on the Ear... Banded Iron Formations(BIFs) are chemical sediments, ubiquitously distributed in the Precambrian supracrustal belts; thus their trace element compositions are helpful for deciphering geochemical evolution on the Earth through time. However, it is necessary to elucidate factors controlling the whole-rock compositions in order to decode the ancient seawater compositions because their compositions are highly variable. We analyzed major and trace element contents of the BIFs in the 3.8-3.7 Ga Isua supracrustal belt(ISB), southern West Greenland. The BIFs are petrographically classified into four types:Black-,Gray-, Green-and White-types, respectively. The Green-type BIFs contain more amphiboles, and are significantly enriched in Co, Ni, Cu, Zn, Y, heavy rare earth element(HREE) and U contents. However,their bulk compositions are not suitable for estimate of seawater composition because the enrichment was caused by secondary mobility of metamorphic Mg, Ca and Si-rich fluid, involvement of carbonate minerals and silicate minerals of olivine and pyroxene and/or later silicification or contamination of volcanic and clastic materials. The White-type BIFs are predominant in quartz, and have lower transition element and REE contents. The Gray-type BIFs contain both quartz and magnetite. The Black-type BIFs are dominated by magnetite, and contain moderate to high transition element and REE contents. But,positive correlations of V, Ni, Zn and U contents with Zr contents suggest that involvement of detrital,volcanic and exhalative materials influences on their contents. The evidence for significant influence of the materials on the transition element contents such as Ni in the BIFs indicates the transition element contents in the Archean ocean were much lower than previously estimated. We reconstructed secular variations of V,Co, Zn and U contents of BIFs through time, which show Ni and Co contents decreased whereas V, Zn and U contents increased through time. Especially, the Ni and Co contents drastically decreased in the Mesoarchean rather than around the Great Oxidation Event. On the other hand, the V,Zn and U contents progressively increased from the Mesoarchean to the Proterozoic. Stratigraphical trends of the BIFs show increase in Y/Ho ratios and decrease in positive Eu anomaly upwards, respectively. The stratigraphic changes indicate that a ratio of hydrothermal fluid to seawater component gradually decrease through the deposition, and support the Eoarchean plate tectonics, analogous to the their stratigraphic variations of seafloor metalliferous sediments at present and in the Mesoarchean. 展开更多
关键词 Banded iron formations Eoarchean Isua supracrustal belt Bioessential elements Seawater compositions
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Age and Origin of Paleogene Granitoids from Western Yunnan Province,China:Geochemistry,SHRIMP Zircon Ages,and Hf-in-Zircon Isotopic Compositions 被引量:3
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作者 SHI Yuruo WU Zhonghai +2 位作者 Alfred KRoNER FAN Taoyuan YANG Zhenyu 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第5期1601-1615,共15页
We report geochemical data, SHRIMP zircon ages and Hf-in-zircon isotopic compositions for Cenozoic granitoids from major fault systems in the Tethyan belt in western Yunnan Province, southwestern China.Four magmatic p... We report geochemical data, SHRIMP zircon ages and Hf-in-zircon isotopic compositions for Cenozoic granitoids from major fault systems in the Tethyan belt in western Yunnan Province, southwestern China.Four magmatic pulses occurred in the Paleogene, namely at ca.57 Ma, ca.50 Ma, 45–40 Ma, and 38–34 Ma.Early magmatism of this episode(57–50 Ma) produced S-type granites whose zircons yielded εHf(t) values of-5.0 to-0.3.In contrast, late magmatism of this episode reflects heterogeneous sources.Zircons from a granite porphyry along the Ailaoshan-Red River fault system have slightly positive εHf(t) values suggesting derivation from relatively young crust and/or a juvenile source.However, zircons from a granite along the Gaoligong fault system have strongly negative εHf(t) values and suggest derivation from a Paleoproterozoic crustal source.The composition of the granitoids varies with age(from ca.57 Ma to ca.34 Ma) from peraluminous to metaluminous and also suggests a change from syn-collisional to late-orogenic tectonic setting.A new tectonic model, impacting lithospheric wedge(ILW) is shown for the origin of Paleogene granitoids in this paper. 展开更多
关键词 PALEOGENE magmatism SHRIMP zircon ages Hf-in-zircon isotopic compositions western Yunnan
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Origin of natural sulfur-metal chimney in the Tangyin hydrothermal field,Okinawa Trough:constraints from rare earth element and sulfur isotopic compositions 被引量:3
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作者 Hong Cao Zhi-lei Sun +3 位作者 Chang-ling Liu En-tao Liu Xue-jun Jiang Wei Huang 《China Geology》 2018年第2期225-235,共11页
For the first time,we present the rare earth element (REE)and sulfur isotopic composition of hydrothermal precipitates recovered from the Tangyin hydrothermal field (THF),Okinawa Trough at a water depth of 1206 m.The ... For the first time,we present the rare earth element (REE)and sulfur isotopic composition of hydrothermal precipitates recovered from the Tangyin hydrothermal field (THF),Okinawa Trough at a water depth of 1206 m.The natural sulfur samples exhibit the lowest ∑REE concentrations (∑REE= 0.65×10^-6-4.580×10^-6)followed by metal sulfides (∑REE=1.71×10^-6-11.63×10^-6).By contrast,the natural sulfur-sediment samples have maximum ∑REE concentrations (∑REE=1 1.54×10^-6-33.06×10^-6), significantly lower than those of the volcanic and sediment samples.Nevertheless,the δEu,δCe,(La/Yb)N, La/Sm,(Gd/Yb)N and normalized patterns of the natural sulfur and metal sulfide show the most similarity to the sediment.Most hydrothermal precipitate samples are characterized by enrichments of LREE (LREE/HREE=10.09-24.53)arid slightly negative Eu anomalies or no anomaly (δEu=0.48-0.99),which are different from the hydrothermal fluid from sediment-free mid-oceanic ridges and back-are basins,but identical to the sulfides from the Jade hydrothermal field.The lower temperature and more oxidizing conditions produced by the mixing between seawater and hydrothermal fluids further attenuate the leaching ability of hydrothermal fluid,inducing lower REE concentrations for natural sulfur compared with metal sulfide;meanwhile,the negative Eu anomaly is also weakened or almost absent.The sulfur isotopic compositions of the natural sulfur (δ^34S=3.20‰-5.01‰,mean 4.23 ‰)and metal sulfide samples (δ34S=0.82‰-0.89‰,mean 0.85‰)reveal that the sulfur of the chimney is sourced from magmatic degassing. 展开更多
关键词 Hydrothormal processes NATURAL SULFUR Isotopic compositions REE Tangyin field OKINAWA TROUGH China
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