In lacustrine sediments,aragonite is a widespread mineral,whereas monohydrocalcite is a rare carbonate mineral. In the cold and high-attitude Xizang (Tibetan) Plateau,where aragonite has been commonly found in lacustr...In lacustrine sediments,aragonite is a widespread mineral,whereas monohydrocalcite is a rare carbonate mineral. In the cold and high-attitude Xizang (Tibetan) Plateau,where aragonite has been commonly found in lacustrine sediments,there is no aragonite,but low-Mg calcite,monohydrocalcite and trace dolomite. The lake receives solutes primarily from surface runoffs and remains fairly constant water chemistry for a long time. The total CaCO3 percentage in sediments could be controlled by evaporation and inflow of detrital materials. The absence of aragonite is unusual when compared to other lacustrine sediments from the Tibetan Plateau. This could be due to low Ca/Mg ratio,low salinity,low Mg and Ca concentration. Monohydrocalcite might precipitate from the lake water mediated by biological activities. Low-Mg calcite originated from minor ostracoda shell and the precipitation of lake water with biological activities.展开更多
[Objective] The study aimed to find an efficient and sustainable way to improve the degraded soil quality in the semiarid Loess Plateau. [Method] This study was done with three treatments： （1） the perennial legume ...[Objective] The study aimed to find an efficient and sustainable way to improve the degraded soil quality in the semiarid Loess Plateau. [Method] This study was done with three treatments： （1） the perennial legume species alfalfa （Medicago sativa L.） （AF） planted at a density of 22.5 kg/hm 2 ; （2） the biennial legume species sweetclover （Melilotus officinalis L.） （SF） planted at a density of 11.3 kg/hm 2 ; and （3） natural regeneration （NR）. [Result] It is found that NR helped improve deep soil water but with the lowest aboveground biomass. In contrast, AF has the lowest soil water content but with the highest aboveground biomass. Furthermore, in contrast to SF, NR and AF have a higher soil organic carbon and total nitrogen. However, there were no significant differences on soil total and available phosphorus, and soil microbial biomass among all the treatments. As the experiment lasts, AP decreased significantly in all treatments in comparison with their initial values at the beginning of the experiment in 2003. [Conclusion] NR was the best way to restore the deep soil water among all the treatments, and phosphorus fertilizer was necessary for the sustainable development of agricultural production. This research provides a valuable example of soil quality restoration in semiarid regions.展开更多
Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial ...Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial Period. The results cover the late Last Deglacial Period and the Holocene. The climate was very unstable and rather arid during the late Last Deglacial Period. The Holocene can be divided into three periods： the early Holocene （11360-8240 cal aB. P. ）, which was dry but unstable and featured rising temperatures, the mid-Holocene （8240-3200 cal aB. P. ）, which was warm and wet and the late Holocene （ since 3200 cal aBP）, which was cold and dry. Results also show a warm-wet event around 1500 cal aB. P.展开更多
Insecurity and asymmetry in all their ramifications are ideological. They are also inherently communicative processes that are largely constructed and enacted through language in various institutional discourses. In U...Insecurity and asymmetry in all their ramifications are ideological. They are also inherently communicative processes that are largely constructed and enacted through language in various institutional discourses. In Urhobo, sex proverbs copiously couch the ideological conceptualizations of the male-female biological asymmetry. Studies on Urhobo proverbs dwell largely on functional applications and documentations of the proverbs, thereby overlooking their ideological underpinnings. Therefore, in this paper, efforts are geared toward investigating and unravelling ideologies that have been habitualized in the semantic and pragmatic structures of the Urhobo sex proverbs. The intention is to throw open the patterns of relationship between the male and female participants in the society in relation to sex matters and power. Twenty-six Urhobo indigenes （six males and 20 females）, who are competent in the socioculture and language were successfully interviewed to elicit Urhobo sex proverbs. Proverbs that contain the following lexical items： penis, virgina, to make love, or to have sex are purposively selected and subjected to CDA （critical discourse analysis）. The main assumption of CDA is that language is both the site and the stake in the struggle for power and domination. Findings show that in the Urhobo sex proverbs, there is asymmetry in access to sexual relations between the male and female. Although the sex proverbs do not always refer to copulation, they are often employed as powerful instruments to dominate and instil fear in the female participant. Consequently, patriarchal discourses are further entrenched in the society展开更多
Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy.However,the homeland security hypothesis suggests that some native plants can resist invasion by pr...Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy.However,the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants.Most research has focused on allelopathic interactions between individual native and invasive plant species,with less emphasis on how allelopathy helps entire native communities resist invasions.Additionally,limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities,and their influence on invasion success.To bridge this knowledge gap,we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species,Betula fruticosa,and a community of four native herbaceous species(Sanguisorba officinalis,Gentiana manshurica,Sium suave and Deyeuxia angustifolia)in China.We assessed whether B.fruticosa and the native community differed in their competitive effects and responses,and whether these were influenced by activated carbon,which neutralizes allelochemicals in the soil.Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B.fruticosa,which indicates that the native community exerted a strong allelopathic effect on B.fruticosa.In contrast,activated carbon only marginally enhanced the suppressive effects of B.fruticosa on the native community,which indicates that allelopathy is not the primary mechanism by which B.fruticosa exerts its suppression.Overall,these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B.fruticosa.展开更多
Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontriviai scheme has attracted great interests because o~ its...Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontriviai scheme has attracted great interests because o~ its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.展开更多
A concise total synthesis of(R,R)-secoisolariciresinol was achieved in four steps, featuring a biomimetic β-β’ radical coupling of two dihydroferulic acid derivatives. The conversion of secoisolariciresinol to othe...A concise total synthesis of(R,R)-secoisolariciresinol was achieved in four steps, featuring a biomimetic β-β’ radical coupling of two dihydroferulic acid derivatives. The conversion of secoisolariciresinol to other related lignans was ongoing.展开更多
基金supported by the National Basic Research Program of China (2005CB422000)the National Natural Science Foundation of China (40801075, 40830743, 40701194, 40671023, and 40730101)
文摘In lacustrine sediments,aragonite is a widespread mineral,whereas monohydrocalcite is a rare carbonate mineral. In the cold and high-attitude Xizang (Tibetan) Plateau,where aragonite has been commonly found in lacustrine sediments,there is no aragonite,but low-Mg calcite,monohydrocalcite and trace dolomite. The lake receives solutes primarily from surface runoffs and remains fairly constant water chemistry for a long time. The total CaCO3 percentage in sediments could be controlled by evaporation and inflow of detrital materials. The absence of aragonite is unusual when compared to other lacustrine sediments from the Tibetan Plateau. This could be due to low Ca/Mg ratio,low salinity,low Mg and Ca concentration. Monohydrocalcite might precipitate from the lake water mediated by biological activities. Low-Mg calcite originated from minor ostracoda shell and the precipitation of lake water with biological activities.
基金Supported by the Special Fund for Scientific Research in the Public Interest of Ministry of Agriculture(201203030)a grant from the Department of Science and Technology of Anhui Province(1206c0805033)the Special Foundation of the President of Anhui Academy of Agricultural Sciences for Young Scholars(11B1021)~~
文摘[Objective] The study aimed to find an efficient and sustainable way to improve the degraded soil quality in the semiarid Loess Plateau. [Method] This study was done with three treatments： （1） the perennial legume species alfalfa （Medicago sativa L.） （AF） planted at a density of 22.5 kg/hm 2 ; （2） the biennial legume species sweetclover （Melilotus officinalis L.） （SF） planted at a density of 11.3 kg/hm 2 ; and （3） natural regeneration （NR）. [Result] It is found that NR helped improve deep soil water but with the lowest aboveground biomass. In contrast, AF has the lowest soil water content but with the highest aboveground biomass. Furthermore, in contrast to SF, NR and AF have a higher soil organic carbon and total nitrogen. However, there were no significant differences on soil total and available phosphorus, and soil microbial biomass among all the treatments. As the experiment lasts, AP decreased significantly in all treatments in comparison with their initial values at the beginning of the experiment in 2003. [Conclusion] NR was the best way to restore the deep soil water among all the treatments, and phosphorus fertilizer was necessary for the sustainable development of agricultural production. This research provides a valuable example of soil quality restoration in semiarid regions.
文摘Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial Period. The results cover the late Last Deglacial Period and the Holocene. The climate was very unstable and rather arid during the late Last Deglacial Period. The Holocene can be divided into three periods： the early Holocene （11360-8240 cal aB. P. ）, which was dry but unstable and featured rising temperatures, the mid-Holocene （8240-3200 cal aB. P. ）, which was warm and wet and the late Holocene （ since 3200 cal aBP）, which was cold and dry. Results also show a warm-wet event around 1500 cal aB. P.
文摘Insecurity and asymmetry in all their ramifications are ideological. They are also inherently communicative processes that are largely constructed and enacted through language in various institutional discourses. In Urhobo, sex proverbs copiously couch the ideological conceptualizations of the male-female biological asymmetry. Studies on Urhobo proverbs dwell largely on functional applications and documentations of the proverbs, thereby overlooking their ideological underpinnings. Therefore, in this paper, efforts are geared toward investigating and unravelling ideologies that have been habitualized in the semantic and pragmatic structures of the Urhobo sex proverbs. The intention is to throw open the patterns of relationship between the male and female participants in the society in relation to sex matters and power. Twenty-six Urhobo indigenes （six males and 20 females）, who are competent in the socioculture and language were successfully interviewed to elicit Urhobo sex proverbs. Proverbs that contain the following lexical items： penis, virgina, to make love, or to have sex are purposively selected and subjected to CDA （critical discourse analysis）. The main assumption of CDA is that language is both the site and the stake in the struggle for power and domination. Findings show that in the Urhobo sex proverbs, there is asymmetry in access to sexual relations between the male and female. Although the sex proverbs do not always refer to copulation, they are often employed as powerful instruments to dominate and instil fear in the female participant. Consequently, patriarchal discourses are further entrenched in the society
基金supported by the National Natural Science Foundation of China(NSFC:41901054)the Chinese Academy of Sciences(CAS-PIFI:2021VBB0004).
文摘Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy.However,the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants.Most research has focused on allelopathic interactions between individual native and invasive plant species,with less emphasis on how allelopathy helps entire native communities resist invasions.Additionally,limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities,and their influence on invasion success.To bridge this knowledge gap,we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species,Betula fruticosa,and a community of four native herbaceous species(Sanguisorba officinalis,Gentiana manshurica,Sium suave and Deyeuxia angustifolia)in China.We assessed whether B.fruticosa and the native community differed in their competitive effects and responses,and whether these were influenced by activated carbon,which neutralizes allelochemicals in the soil.Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B.fruticosa,which indicates that the native community exerted a strong allelopathic effect on B.fruticosa.In contrast,activated carbon only marginally enhanced the suppressive effects of B.fruticosa on the native community,which indicates that allelopathy is not the primary mechanism by which B.fruticosa exerts its suppression.Overall,these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B.fruticosa.
基金Supported by the National Natural Science Foundation of China under Grant No.61303039Sichuan Youth Science and Technique Foundation No.2017JQ0048+2 种基金Fundamental Research Funds for the Central Universities(Nos.2682014CX095)CSC ScholarshipEU ICT COST Crypto Action No.IC1306
文摘Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontriviai scheme has attracted great interests because o~ its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.
基金The Drug Innovation Major Project(Grant No.2018ZX09711-001-005-005)
文摘A concise total synthesis of(R,R)-secoisolariciresinol was achieved in four steps, featuring a biomimetic β-β’ radical coupling of two dihydroferulic acid derivatives. The conversion of secoisolariciresinol to other related lignans was ongoing.
