The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modificat...The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.展开更多
The exploration of low bandgap perovskite material to approach Shockley-Queisser limit of photovoltaic device is of great significance,but it is still challenging.During the past few years,tin–lead(Sn-Pb)mixed perovs...The exploration of low bandgap perovskite material to approach Shockley-Queisser limit of photovoltaic device is of great significance,but it is still challenging.During the past few years,tin–lead(Sn-Pb)mixed perovskites with low bandgaps have been rapidly developed,and their single junction solar cells have reached power conversion efficiency(PCE)over 21%,which also makes them ideal candidate as low bandgap sub-cell for tandem device.Nevertheless,due to the incorporation of unstable Sn^(2+),the stability issue becomes the vital problem for the further development of Sn-Pb mixed perovskite solar cells(PSCs).In this review,we are dedicated to give a full view in current understanding on the stability issue of SnPb mixed perovskites and their PSCs.We begin with the demonstration on the origin of instability of Sn-Pb mixed perovskites,including oxidation of Sn^(2+),defects,and interfacial layer induced instability.Sequentially,the up-to-date developments on the stability improvement of Sn-Pb mixed perovskites and their PSCs is systematically reviewed,including composition engineering,additive engineering,and interfacial engineering.At last,the current challenges and future perspectives on the stability study of Sn-Pb mixed PSCs are discussed,which we hope could promote the further application of Sn-Pb mixed perovskites towards commercialization.展开更多
Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize ( Zea ma...Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize ( Zea mays, cv. Katumani Composite B), may be expected to exceed those in the control (sole maize) plots. Such yields were insufficient to compensate for the area “lost” to the hedgerows. Below about 150 mm the control plots may be expected to perform better. This result was due to competition for water. Greater association of the fine roots of Cassia and maize was observed in the middle of the alleys than near the hedgerows. Photosynthetic consequences of shading were insignificant relative to other factors. In the alleys, reductions of soil temperature due to shade in the western and eastern maize rows were higher than in the middle row. Soil moisture extraction was higher in the AF than in the control plots. In the AF plots, moisture extraction was greater under the central maize rows than under those nearest the Cassia. Yield patterns followed such soil temperature and soil moisture patterns. Maize transpiration and photosynthetic rates were significantly higher in the control than in the AF plots during a below average rainy season but not during above average rainy seasons. It is concluded that alley cropping under semi arid conditions should be approached differently from the system worked on. It must at least provide strong physical protection of crops and/or soils and have a strong economic incentive to be of interest to the farmers.展开更多
Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sow...Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (CM). Sole maize (SM) and CM yields were higher in SR88 than in the long rains of 1988 (LR88) by 62% and 38%, while yields from the same treatments in LR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.展开更多
The linguistic landscape of traditional historic tourist attractions has undergone heterogeneous changes under the impact of globalization and tourism development.Guided by the linguistic landscape construction princi...The linguistic landscape of traditional historic tourist attractions has undergone heterogeneous changes under the impact of globalization and tourism development.Guided by the linguistic landscape construction principle and meaning combination analysis,taking the linguistic landscape of South Luogu Al ey in Beijing as the research object,its unique presentation and formation mechanism are analyzed and explicated in this paper.In the first part,we describe the elements of tradition and modernity presented in both private and official linguistic landscape.In the second part,we explain these characteristics,and the results show that:traditional elements dominated with each presents unique characteristics while modern elements especially English have been extensively employed than ever before,functioning as the information disseminator and prestige symbol.Finally,certain degrees of problems need to be meticulously considered so as to foster the renewal progress of the historic tourist attractions.展开更多
The English translation of modern and contemporary Chinese poetry can help“Chinese culture go abroad”,which has far-reaching influence on the culture communication.Therefore,the accurate understanding of the metapho...The English translation of modern and contemporary Chinese poetry can help“Chinese culture go abroad”,which has far-reaching influence on the culture communication.Therefore,the accurate understanding of the metaphors in poetry is extremely necessary.This paper takes Dai Wangshu’s poem“Rainy Alley”and its English translations as the research subjects,and explores the different understandings of metaphors in Chinese and Western cultures from the perspective of cognitive linguistic.This paper finds out that the translation of metaphors in poetry should always base on the“emotion”so as to accurately translate the poetry.展开更多
TOURISTS traveling to Beijing always have the Great Wall,Tiananmen Square and the Forbidden City on their must-see list.But what if you have already seen the sights?Then it’s time to explore the ancient capital’s hu...TOURISTS traveling to Beijing always have the Great Wall,Tiananmen Square and the Forbidden City on their must-see list.But what if you have already seen the sights?Then it’s time to explore the ancient capital’s hutongs.Featured this issue is Nanluoguxiang Alley,one of downtown Beijing’s best preserved hutongs.With its grey-walled courtyard homes,it offers a real taste of traditional city life. Located several kilometers north of the Forbidden City and east of Houhai Lake, Nanluoguxiang Alley is a 786-meter-long and 8-meter-wide lane.It stretches northsouth from Gulou East Street to Di’anmen East Street.展开更多
文摘The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.
基金financially supported by the National Natural Science Foundation of China(Grants 51972172,61705102,91833304 and 51802253)the Natural Science Basic Research Plan in Shaanxi Province of China(2019JM-326)+5 种基金the Joint Research Funds of Department of Science&Technology of Shaanxi Province and Northwestern Polytechnical University(No.2020GXLH-Z007)the Natural Science Foundation of Jiangsu Province for Distinguished Young Scholars,China(Grant BK20200034)the Young 1000 Talents Global Recruitment Program of ChinaJiangsu Specially Appointed Professor program“Six talent peaks”Project in Jiangsu Province,Chinathe Fundamental Research Funds for the Central Universities。
文摘The exploration of low bandgap perovskite material to approach Shockley-Queisser limit of photovoltaic device is of great significance,but it is still challenging.During the past few years,tin–lead(Sn-Pb)mixed perovskites with low bandgaps have been rapidly developed,and their single junction solar cells have reached power conversion efficiency(PCE)over 21%,which also makes them ideal candidate as low bandgap sub-cell for tandem device.Nevertheless,due to the incorporation of unstable Sn^(2+),the stability issue becomes the vital problem for the further development of Sn-Pb mixed perovskite solar cells(PSCs).In this review,we are dedicated to give a full view in current understanding on the stability issue of SnPb mixed perovskites and their PSCs.We begin with the demonstration on the origin of instability of Sn-Pb mixed perovskites,including oxidation of Sn^(2+),defects,and interfacial layer induced instability.Sequentially,the up-to-date developments on the stability improvement of Sn-Pb mixed perovskites and their PSCs is systematically reviewed,including composition engineering,additive engineering,and interfacial engineering.At last,the current challenges and future perspectives on the stability study of Sn-Pb mixed PSCs are discussed,which we hope could promote the further application of Sn-Pb mixed perovskites towards commercialization.
文摘Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize ( Zea mays, cv. Katumani Composite B), may be expected to exceed those in the control (sole maize) plots. Such yields were insufficient to compensate for the area “lost” to the hedgerows. Below about 150 mm the control plots may be expected to perform better. This result was due to competition for water. Greater association of the fine roots of Cassia and maize was observed in the middle of the alleys than near the hedgerows. Photosynthetic consequences of shading were insignificant relative to other factors. In the alleys, reductions of soil temperature due to shade in the western and eastern maize rows were higher than in the middle row. Soil moisture extraction was higher in the AF than in the control plots. In the AF plots, moisture extraction was greater under the central maize rows than under those nearest the Cassia. Yield patterns followed such soil temperature and soil moisture patterns. Maize transpiration and photosynthetic rates were significantly higher in the control than in the AF plots during a below average rainy season but not during above average rainy seasons. It is concluded that alley cropping under semi arid conditions should be approached differently from the system worked on. It must at least provide strong physical protection of crops and/or soils and have a strong economic incentive to be of interest to the farmers.
文摘Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (CM). Sole maize (SM) and CM yields were higher in SR88 than in the long rains of 1988 (LR88) by 62% and 38%, while yields from the same treatments in LR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.
基金Sponsored by Campus Culture Project of Beijing Jiaotong University:Cross-cultural Study of Campus Official English Translation from the Perspective of International Publicity (162085522)。
文摘The linguistic landscape of traditional historic tourist attractions has undergone heterogeneous changes under the impact of globalization and tourism development.Guided by the linguistic landscape construction principle and meaning combination analysis,taking the linguistic landscape of South Luogu Al ey in Beijing as the research object,its unique presentation and formation mechanism are analyzed and explicated in this paper.In the first part,we describe the elements of tradition and modernity presented in both private and official linguistic landscape.In the second part,we explain these characteristics,and the results show that:traditional elements dominated with each presents unique characteristics while modern elements especially English have been extensively employed than ever before,functioning as the information disseminator and prestige symbol.Finally,certain degrees of problems need to be meticulously considered so as to foster the renewal progress of the historic tourist attractions.
基金supported by the Fund of Key Research Projects of Humanities and Social Sciences in Colleges and Universities of Guangdong Province[2018WZDXM010]the Fund of Graduate Research Innovation program of Guangdong University of Foreign Studies[22GWCXXM-108].
文摘The English translation of modern and contemporary Chinese poetry can help“Chinese culture go abroad”,which has far-reaching influence on the culture communication.Therefore,the accurate understanding of the metaphors in poetry is extremely necessary.This paper takes Dai Wangshu’s poem“Rainy Alley”and its English translations as the research subjects,and explores the different understandings of metaphors in Chinese and Western cultures from the perspective of cognitive linguistic.This paper finds out that the translation of metaphors in poetry should always base on the“emotion”so as to accurately translate the poetry.
文摘TOURISTS traveling to Beijing always have the Great Wall,Tiananmen Square and the Forbidden City on their must-see list.But what if you have already seen the sights?Then it’s time to explore the ancient capital’s hutongs.Featured this issue is Nanluoguxiang Alley,one of downtown Beijing’s best preserved hutongs.With its grey-walled courtyard homes,it offers a real taste of traditional city life. Located several kilometers north of the Forbidden City and east of Houhai Lake, Nanluoguxiang Alley is a 786-meter-long and 8-meter-wide lane.It stretches northsouth from Gulou East Street to Di’anmen East Street.
