Decomposition of soil organic matter(SOM) is of importance for CO_2 exchange between soil and atmosphere and soil temperature and moisture are considered as two important factors controlling SOM decomposition. In this...Decomposition of soil organic matter(SOM) is of importance for CO_2 exchange between soil and atmosphere and soil temperature and moisture are considered as two important factors controlling SOM decomposition. In this study, soil samples were collected at 5 elevations ranging from 753 to 2 357 m on the Changbai Mountains in Northeast China, and incubated under different temperatures(5, 10, 15, 20, 25, and 30?C) and soil moisture levels(30%, 60%, and 90% of saturated soil moisture) to investigate the effects of both on SOM decomposition and its temperature sensitivity at different elevations. The results showed that incubation temperature(F = 1 425.10, P < 0.001), soil moisture(F = 1 327.65, P < 0.001), and elevation(F = 1 937.54, P < 0.001) all had significant influences on the decomposition rate of SOM. The significant effect of the interaction of incubation temperature and soil moisture on the SOM decomposition rate was observed at all the 5 sampling elevations(P < 0.001). A two-factor model that used temperature and moisture as variables fitted the SOM decomposition rate well(P < 0.001) and could explain 80%–93% of the variation of SOM decomposition rate at the 5 elevations. Temperature sensitivity of SOM decomposition, expressed as the change of SOM decomposition rate in response to a 10?C increase in temperature(Q_(10)), was significantly different among the different elevations(P < 0.01), but no apparent trend with elevation was discernible. In addition, soil moisture and incubation temperature both had great impacts on the Q_(10) value(P < 0.01), which increased significantly with increasing soil moisture or incubation temperature. Furthermore, the SOM decomposition rate was significantly related to soil total Gram-positive bacteria(R^2= 0.33, P < 0.01) and total Gram-negative bacteria(R^2= 0.58, P < 0.001). These findings highlight the importance of soil moisture to SOM decomposition and its Q_(10) value,which needs to be emphasized under warming climate scenarios.展开更多
The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics(~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic...The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics(~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic rocks from the Lichi volcanics, which are exposed in the Ranga valley, along the Kimin-Yazali road section in the Eastern Himalayan Region, Northeast India. The trachytes occur in close association with sandstones of the Gondwana Group of rocks and are characterised based on field, petrographical, and geochemical investigations.These fine-grained trachytes are composed of alkali feldspar, biotite, plagioclase, sodic-amphibole, apatite, illmenite, and titanite. The REE profiles of the evolved trachytic rocks(higher SiO_(2)content) display fractionated trends. The fractionation of accessory mineral phases, like apatite and titanite, was possibly responsible for the strongly fractionated REE patterns of the evolved samples.The trachytic rocks demonstrate high apatite saturation temperatures of 988 ± 14 ℃(1σ, n = 8). The Aluminium Saturation Index(< 1.1) and binary discrimination diagrams of these peralkaline trachytes define their affinity with A-type granitoids. Elemental ratios like Y/Nb, Nb/U,and Ce/Pb signify that the Lichi trachytes are differentiated products of mantle-derived ocean island basalts. Trace elemental discrimination diagrams Th/Yb versus Nb/Yb, Y versus Nb, and Y + Nb versus Rb reflect a within-plate tectonic regime for the trachytes. From the results presented in this work, we infer that the development of rifting events during the breakup of eastern Gondwana due to the onset of Kerguelen plume activity further led to underplating of basic magma in lower crustal levels. These parental basaltic magmas underwent fractionation processes forming differentiated trachyandesites and trachytes.Taking into consideration the similarities recorded between the Lichi volcanics and Abor volcanics, this study supports the idea that Kerguelen plume activities resulted in the emplacement of these volcanics in the Eastern Himalayas.展开更多
In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size...In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size and layer numbers of graphene sheets increase with the arc current.Distributions of temperature, velocity, and mass fraction of carbon are obtained through numerical simulations. A high current corresponds to a high saturation temperature, evaporation rate, and mass density of carbon clusters. When the carbon vapor is saturated, the saturation temperatures are 3274.9, 3313.9, and 3363.6 K, and the mass densities are 6.4×1022,8.42×1022, and 1.23×1023 m-3 under currents of 150, 200, and 250 A, respectively. A hydrogen-induced marginal growth model is used to explain the growth mechanism. Under a high current, the condensation coefficient and van der Waals force increase owing to the higher saturation temperature and mass density of carbon clusters, which is consistent with experimental results.展开更多
Saturated vapor pressure, critical evaporation temperature and evaporation loss rate of Fe-Ga alloy were calculated under different conditions of Ga and Fe contents with activity coefficients. The relationship between...Saturated vapor pressure, critical evaporation temperature and evaporation loss rate of Fe-Ga alloy were calculated under different conditions of Ga and Fe contents with activity coefficients. The relationship between the change of Ga content and melting time was determined. The results demonstrated that saturated vapor pressure of Ga was higher than that of Fe under the same conditions. The difference value of critical evaporation temperature of Ga with and without Ar was nearly 800 K. The critical evaporation temperature of Fe was higher than that of Ga under vacuum, indicating that Ga was more volatile than Fe. At 1800 K, the evaporation rate of Ga was 84 times higher than that of Fe in the melt of Fe81Ga19 alloy. Under this condition, the change of Ga content and smelting time kept a linear relationship. The higher the temperature was, the faster the Ga content decreased, which was consistent with theoretical calculations.展开更多
An attempt has been made to investigate the role of vertical wind shear, convective instability and the thermodynamic parameter ( θ es -θ e ) below the first lifting condensation level (FLCL) in the occurrenc...An attempt has been made to investigate the role of vertical wind shear, convective instability and the thermodynamic parameter ( θ es -θ e ) below the first lifting condensation level (FLCL) in the occurrence of instantaneous premonsoon thunderstorm over Agartala (AGT) and Ranchi (RNC) at 12 GMT. Radiosonde data of 1988 have been utilized here. The study has however been confined to 1000 hPa-500 hPa range at most. Here the convectively unstable layers with positive vertical wind shear upto 500 hPa have been termed as ‘Favourable Layers’ (FL) and the level at which an initially stable layer turns out to be convectively unstable for the first time has been termed as ‘Transition Level’ (TL). It is observed that the changes in vertical wind shear are positive at TL at the time of occurrence of thunderstorm (TS) and the corresponding change is negative on fair-weather situation. Moreover, the 90% confidence interval for ( θ es -θ e ) reveals that for AGT the upper layer thermodynamic characteristic is important at the time of occurrence of TS whereas for RNC, the value of ( θ es -θ e ) at the surface is much more effective.展开更多
The gelation properties of polyol acetal derivatives including 2,4-（3,4-dichlorobenzylidene）-D-sorbitol（DCBS）, 1,3：2,4-di（3,4-dichlorobenzylidene）-D-sorbitol（DDCBS） and 1,3：2,5：4,6-tris（3,4-dichlorobenzyli...The gelation properties of polyol acetal derivatives including 2,4-（3,4-dichlorobenzylidene）-D-sorbitol（DCBS）, 1,3：2,4-di（3,4-dichlorobenzylidene）-D-sorbitol（DDCBS） and 1,3：2,5：4,6-tris（3,4-dichlorobenzylidene）-D-mannitol（TDCBM） in 35 single solvents and 39 binary solvent mixtures have been studied. FTIR and XRD results suggest that the self-assembly patterns of the gelator will not change in either the single solvent component or the corresponding solvent mixtures, but the critical gelation concentration（CGC）will be influenced. The results of SEM and rheology showed that the formation of true gels at saturated concentrations. Improving the heating temperature may promote the dissolving of gelators which are even insoluble at the temperature of the solvent boiling point and change the gelation behaviors. FloryHuggins parameter（x） was used to predict the gelation behavior of DCBS in the mixed solvents, and it is shown that the x values for the mixed solvents that can be gelled by DCBS are either greater or smaller than those for the selected good solvents.展开更多
基金supported by the National Natural Science Foundation of China(No.31290221)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05050601)the Program for “Kezhen” Distinguished Talents in the Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences(No.2013RC102)
文摘Decomposition of soil organic matter(SOM) is of importance for CO_2 exchange between soil and atmosphere and soil temperature and moisture are considered as two important factors controlling SOM decomposition. In this study, soil samples were collected at 5 elevations ranging from 753 to 2 357 m on the Changbai Mountains in Northeast China, and incubated under different temperatures(5, 10, 15, 20, 25, and 30?C) and soil moisture levels(30%, 60%, and 90% of saturated soil moisture) to investigate the effects of both on SOM decomposition and its temperature sensitivity at different elevations. The results showed that incubation temperature(F = 1 425.10, P < 0.001), soil moisture(F = 1 327.65, P < 0.001), and elevation(F = 1 937.54, P < 0.001) all had significant influences on the decomposition rate of SOM. The significant effect of the interaction of incubation temperature and soil moisture on the SOM decomposition rate was observed at all the 5 sampling elevations(P < 0.001). A two-factor model that used temperature and moisture as variables fitted the SOM decomposition rate well(P < 0.001) and could explain 80%–93% of the variation of SOM decomposition rate at the 5 elevations. Temperature sensitivity of SOM decomposition, expressed as the change of SOM decomposition rate in response to a 10?C increase in temperature(Q_(10)), was significantly different among the different elevations(P < 0.01), but no apparent trend with elevation was discernible. In addition, soil moisture and incubation temperature both had great impacts on the Q_(10) value(P < 0.01), which increased significantly with increasing soil moisture or incubation temperature. Furthermore, the SOM decomposition rate was significantly related to soil total Gram-positive bacteria(R^2= 0.33, P < 0.01) and total Gram-negative bacteria(R^2= 0.58, P < 0.001). These findings highlight the importance of soil moisture to SOM decomposition and its Q_(10) value,which needs to be emphasized under warming climate scenarios.
基金the DST-SERB grant vide Project No. CRG/2020/002635the CSIR-JRF fellowship No. 09/1236(11154)/2021-EMR-Ithe DST-INSPIRE fellowship No. IF210186。
文摘The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics(~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic rocks from the Lichi volcanics, which are exposed in the Ranga valley, along the Kimin-Yazali road section in the Eastern Himalayan Region, Northeast India. The trachytes occur in close association with sandstones of the Gondwana Group of rocks and are characterised based on field, petrographical, and geochemical investigations.These fine-grained trachytes are composed of alkali feldspar, biotite, plagioclase, sodic-amphibole, apatite, illmenite, and titanite. The REE profiles of the evolved trachytic rocks(higher SiO_(2)content) display fractionated trends. The fractionation of accessory mineral phases, like apatite and titanite, was possibly responsible for the strongly fractionated REE patterns of the evolved samples.The trachytic rocks demonstrate high apatite saturation temperatures of 988 ± 14 ℃(1σ, n = 8). The Aluminium Saturation Index(< 1.1) and binary discrimination diagrams of these peralkaline trachytes define their affinity with A-type granitoids. Elemental ratios like Y/Nb, Nb/U,and Ce/Pb signify that the Lichi trachytes are differentiated products of mantle-derived ocean island basalts. Trace elemental discrimination diagrams Th/Yb versus Nb/Yb, Y versus Nb, and Y + Nb versus Rb reflect a within-plate tectonic regime for the trachytes. From the results presented in this work, we infer that the development of rifting events during the breakup of eastern Gondwana due to the onset of Kerguelen plume activity further led to underplating of basic magma in lower crustal levels. These parental basaltic magmas underwent fractionation processes forming differentiated trachyandesites and trachytes.Taking into consideration the similarities recorded between the Lichi volcanics and Abor volcanics, this study supports the idea that Kerguelen plume activities resulted in the emplacement of these volcanics in the Eastern Himalayas.
基金supported by National Natural Science Foundation of China (No. 11765010)the National Key Research and Development Program of China (No. 2019YFC1907900)+2 种基金the Applied Basic Research Programs of Yunnan Provincial Science and Technology Department (No. 202001AW070004)the Freely Exploring Fund for Academicians in Yunnan Province (No. 2018HA006)the Key Laboratory of Resource Chemistry, Ministry of Education (No. KLRCME2001)
文摘In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size and layer numbers of graphene sheets increase with the arc current.Distributions of temperature, velocity, and mass fraction of carbon are obtained through numerical simulations. A high current corresponds to a high saturation temperature, evaporation rate, and mass density of carbon clusters. When the carbon vapor is saturated, the saturation temperatures are 3274.9, 3313.9, and 3363.6 K, and the mass densities are 6.4×1022,8.42×1022, and 1.23×1023 m-3 under currents of 150, 200, and 250 A, respectively. A hydrogen-induced marginal growth model is used to explain the growth mechanism. Under a high current, the condensation coefficient and van der Waals force increase owing to the higher saturation temperature and mass density of carbon clusters, which is consistent with experimental results.
基金Item Sponsored by National Natural Science Foundation of China(51161019)Project of Department of Science and Technology of Jiangxi Province of China(20133BBE50011)Project of Department of Science & Technology of Jiangxi Province of China(20141BDH80025)
文摘Saturated vapor pressure, critical evaporation temperature and evaporation loss rate of Fe-Ga alloy were calculated under different conditions of Ga and Fe contents with activity coefficients. The relationship between the change of Ga content and melting time was determined. The results demonstrated that saturated vapor pressure of Ga was higher than that of Fe under the same conditions. The difference value of critical evaporation temperature of Ga with and without Ar was nearly 800 K. The critical evaporation temperature of Fe was higher than that of Ga under vacuum, indicating that Ga was more volatile than Fe. At 1800 K, the evaporation rate of Ga was 84 times higher than that of Fe in the melt of Fe81Ga19 alloy. Under this condition, the change of Ga content and smelting time kept a linear relationship. The higher the temperature was, the faster the Ga content decreased, which was consistent with theoretical calculations.
文摘An attempt has been made to investigate the role of vertical wind shear, convective instability and the thermodynamic parameter ( θ es -θ e ) below the first lifting condensation level (FLCL) in the occurrence of instantaneous premonsoon thunderstorm over Agartala (AGT) and Ranchi (RNC) at 12 GMT. Radiosonde data of 1988 have been utilized here. The study has however been confined to 1000 hPa-500 hPa range at most. Here the convectively unstable layers with positive vertical wind shear upto 500 hPa have been termed as ‘Favourable Layers’ (FL) and the level at which an initially stable layer turns out to be convectively unstable for the first time has been termed as ‘Transition Level’ (TL). It is observed that the changes in vertical wind shear are positive at TL at the time of occurrence of thunderstorm (TS) and the corresponding change is negative on fair-weather situation. Moreover, the 90% confidence interval for ( θ es -θ e ) reveals that for AGT the upper layer thermodynamic characteristic is important at the time of occurrence of TS whereas for RNC, the value of ( θ es -θ e ) at the surface is much more effective.
基金the financial support of the National Natural Science Foundation of China(No. 21476164)Tianjin Science and Technology Innovation Platform Program(No. 14TXGCCX00017)
文摘The gelation properties of polyol acetal derivatives including 2,4-（3,4-dichlorobenzylidene）-D-sorbitol（DCBS）, 1,3：2,4-di（3,4-dichlorobenzylidene）-D-sorbitol（DDCBS） and 1,3：2,5：4,6-tris（3,4-dichlorobenzylidene）-D-mannitol（TDCBM） in 35 single solvents and 39 binary solvent mixtures have been studied. FTIR and XRD results suggest that the self-assembly patterns of the gelator will not change in either the single solvent component or the corresponding solvent mixtures, but the critical gelation concentration（CGC）will be influenced. The results of SEM and rheology showed that the formation of true gels at saturated concentrations. Improving the heating temperature may promote the dissolving of gelators which are even insoluble at the temperature of the solvent boiling point and change the gelation behaviors. FloryHuggins parameter（x） was used to predict the gelation behavior of DCBS in the mixed solvents, and it is shown that the x values for the mixed solvents that can be gelled by DCBS are either greater or smaller than those for the selected good solvents.
