With the aid of soil column test models,the transport rules of fluorine contaminants in unsaturated stratified soils are discussed. Curves of F-concentrations at different times and sites in the unsaturated stratified...With the aid of soil column test models,the transport rules of fluorine contaminants in unsaturated stratified soils are discussed. Curves of F-concentrations at different times and sites in the unsaturated stratified soil were ob-tained under conditions of continuous injection of fluoride contaminants and water. Based on the analysis of the actual observation data,the values between computed results and observed data were compared. It is shown that the chemical properties of fluorine ions are active. The migration process of fluorine ions in soils is complex. Because of the effect of adsorption and desorption,the curve of the fluorine ion breakthrough curve is not symmetric. Its concentration peak value at each measuring point gradually decays. The tail of the breakthrough curve is long and the process of leaching and purifying using water requires considerable time. Along with the release of OHˉ in the process of fluorine absorp-tion,the pH value of the soil solution changed from neutral to alkalinity during the test process. The first part of the breakthrough curve fitted better than the second part. The main reason is that fluorine does not always exist in the form of fluorinions in groundwater. Given the long test time,fluorinions possibly react with other ions in the soil solution to form complex water-soluble fluorine compounds. Only the retardation factor and source-sink term have been considered in our numerical model,which may leads to errors of computed values. But as a whole the migration rules of fluorine ions are basically correct,which indicates that the established numerical model can be used to simulate the transport rules of fluorine contaminants in unsaturated stratified soils.展开更多
The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils,the gas phase and solid phase are relatively insulated,so the average resistivity of soils can ...The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils,the gas phase and solid phase are relatively insulated,so the average resistivity of soils can be calculated from the resistivity of the liquid phase. On this basis,the two-part model of resistivity changing with the water saturation of the expansive soil can be deduced. A 2-D resistance grid model is established based on simulating the resistance of ver-tically developed fissures. Variation in measured resistance of vertically developed fissures at different positions can be calculated from this model. Fissure development can be inversely determined from the variation in the measured resis-tance. Finally,the model is verified by an indoor resistivity test for remolded soil samples,indicating that the test result agrees well with that of the model established.展开更多
Background Disrupted white matter(WM)microstructure has been commonly identified in youth at clinical high risk(CHR)for psychosis.Several lines of evidence suggest that fatty acids,especially unsaturated fatty acids(U...Background Disrupted white matter(WM)microstructure has been commonly identified in youth at clinical high risk(CHR)for psychosis.Several lines of evidence suggest that fatty acids,especially unsaturated fatty acids(UFAs),might play a crucial role in the WM pathology of early onset psychosis.However,evidence linking UFA and WM microstructure in CHR is quite sparse.Aims We investigated the relationship between the plasma UFA level and WM microstructure in CHR participants and healthy controls(HC).Methods Plasma fatty acids were assessed and diffusion tensor imaging(DTI)data were performed with tract-based spatial statistics(TBSS)analysis for 66 individuals at CHR for psychosis and 70 HC.Results Both the global and regional diffusion measures showed significant between-group differences,with decreased fractional anisotropy(FA)but increased mean diffusivity(MD)and radial diffusivity(RD)found in the CHR group compared with the HC group.On top of that,we found that in the HC group,plasma arachidic acid showed obvious trend-level associations with higher global FA,lower global MD and lower global RD,which regionally spread over the corpus callosum,right anterior and superior corona radiata,bilateral anterior and posterior limb of the internal capsule,and bilateral superior longitudinal fasciculus.However,there were no associations between global WM measures and any UFA in the CHR group.Conversely,we even found negative associations between arachidic acid levels and regional FA values in the right superior longitudinal fasciculus and right retrolenticular part of the internal capsule in the CHR group.Conclusions Compared with the HC group,CHR subjects exhibited a different pattern of association between WM microstructure and plasma UFA,with a neuroprotective effect found in the HC group but not in the CHR group.Such discrepancy could be due to the excessively upregulated UFAs accumulated in the plasma of the CHR group,highlighting the role of balanced plasma-membrane fatty acids homeostasis in WM development.展开更多
The stability of unsaturated soil slope has been the hot point recently. Especially, the seeping rainfall makes losing stability of unsaturated soil slope, and causes enormous loss to the producation and safety of oth...The stability of unsaturated soil slope has been the hot point recently. Especially, the seeping rainfall makes losing stability of unsaturated soil slope, and causes enormous loss to the producation and safety of other people. The seeping rainfall makes volumetric water content of unsaturated soil slope changing, and the volumetric water content has directly relationship with matric suction. And matric suction also has directly relationship with the stability of unsaturated soil slope. So the change of matric suction influence the stability changing, that is, safety coefficient has decided relationship with volumetric water content. The profile of dangerous volumetric water content curves of unsaturated soil slope has been obtained. If a volumetric water content curve of some unsaturated soil slope belongs to one of these dongerous curves, the unsaturated soil slope could be in danger. So this is called DVWCCP(dangerous volumetric water content curves profile). By monitoring the volumetric water content curves can obtain the stability information of some soil slope to serve producing and safety.展开更多
The 7th international conference on unsaturated soils（3rd–5th August 2018）is organised by the Hong Kong University of Science and Technology and supported by：TC106 Unsaturated Soils of ISSMGE;Hong Kong Geotechnica...The 7th international conference on unsaturated soils（3rd–5th August 2018）is organised by the Hong Kong University of Science and Technology and supported by：TC106 Unsaturated Soils of ISSMGE;Hong Kong Geotechnical Society;Geotechnical Division of Hong Kong Institution of Engineers;展开更多
In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies...In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies in the next generation WLAN communication standards.However,the performance of the existing media access control(MAC)degrades significantly under unsaturated services.Therefore,this paper proposes a multi-user parallel contention channel MAC(MU-MAC)based on unsaturated services,which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On this basis,MU-MAC is enhanced for the spatial clustering group(SCG)formation protocol and support for the unsaturated service characteristics.Further,the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally,and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72%and 104.15%,respectively.展开更多
This paper proposes an analysis model of frame aggregation in error-free channel with unsaturated traffic and fixed aggregation size. Integrated with model of channel access, calculation of MAC (Media Access Control) ...This paper proposes an analysis model of frame aggregation in error-free channel with unsaturated traffic and fixed aggregation size. Integrated with model of channel access, calculation of MAC (Media Access Control) average service time and queue model of frame aggregation, our model can get the stable result with a recursive algorithm, and it further derive the throughput and latency of frame aggregation in steady state. As the impact of traffic, frame length, collision probability, buffer size, aggregation size and interactive effects are taken into consideration, the effect of every parameter could be evaluated and the major factor which degrades the performance of frame aggregation can be determined in different situation with this model. By the simulation and numerical analysis, this model confirmed its accuracy. The proposed model can be used in the design, optimization and deployment of WLAN (Wireless Local Area Network) and WMN (Wireless Mesh Network) widely.展开更多
Scheduling schemes assign limited resources to appropriate users,which are critical for wireless network performance.Most current schemes have been designed based on saturated traffic,i.e.,assuming users in networks a...Scheduling schemes assign limited resources to appropriate users,which are critical for wireless network performance.Most current schemes have been designed based on saturated traffic,i.e.,assuming users in networks always have data to transmit.However,the user buffer may sometimes be empty in actual network.Therefore,these algorithms will allocate resources to users having no data to transmit,which results in resource waste.In view of this,we propose new scheduling schemes for onehop and two-hop link scenario with unsaturated traffic.Furthermore,this paper analyzes their key network performance indicators,including the average queue length,average throughput,average delay and outage probability.The two scheduling algorithms avoid scheduling the links whose buffers are empty and thus improve the network resource utilization.For the one-hop link scenario,network provides differentiated services via adjusting the scheduling probabilities of the destination nodes(DNs)with different priorities.Among the DNs with same priority,the node with higher data arrival rate has larger scheduling probability.For the two-hop link scenario,we prioritize the scheduling of relay-to-destination(R-D)link and dynamically adjust the transmission probability of source-to-relay(S-R)link,according to the length of remaining buffer.The experiment results show the effectiveness and advantage of the proposed algorithms.展开更多
Leaching is widely applied in the exploitation of depleted ores. In order to discover the law of leachant movement in the leaching process and calculating volumes and time intervals of spraying leachant,experiments an...Leaching is widely applied in the exploitation of depleted ores. In order to discover the law of leachant movement in the leaching process and calculating volumes and time intervals of spraying leachant,experiments and numerical simulation with the TOUGH2/EOS3 module were carried out in order to find out the principle of water movement in unsaturated copper ore. The results show that water volume increases at the same location over time,that copper ore tends to become saturated and that liquid velocity decreases at the same time as the distance from top in-creases. On the other hand,a comparison and analysis of our experimental and simulated results indicate that the EOS3 module could accurately simulate the water movement in an unsaturated state.展开更多
The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, fo...The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, four treatment schemes were tried. Na 2CO 3 could reduce conspicuously the permeability of the saturated clay, but could not limit the permeability rise in the alternate wetting and drying process. NaOH had a similar effect to Na 2CO 3. NaCl could not only decrease the saturated hydraulic conductivity, but could also effectively contain the permeability rise caused by evaporation. CH 3COONa had a similar effect to NaCl. The mechanism of Na 2CO 3, NaOH, NaCl and CH 3COONa decreasing the saturated hydraulic conductivity of the clay is that Na + transformed Ca montmorillonites in the original clay into Na montmorillonites and the transformation reduces the sizes of effective pores and the effective porosity of the clay.展开更多
OBJECTIVE To investigate three features of dietary cooking oil intake,namely,the consumption,cooking style,and composition of fatty acids in relation to several cardiometabolic measurements in an elderly Chinese popul...OBJECTIVE To investigate three features of dietary cooking oil intake,namely,the consumption,cooking style,and composition of fatty acids in relation to several cardiometabolic measurements in an elderly Chinese population.METHODS The elderly(≥65 years)participants for this study were recruited from two community health centers in the urban area of Shanghai.A questionnaire was administered to collect information on dietary oil consumption(low,medium and high)and cooking styles(fry or stir-fry vs.others)and the composition of fatty acids(poly-unsaturated vs.mono-unsaturated).The cardiometabolic measurements included anthropometry,blood pressure,fasting plasma glucose and serum lipids.RESULTS The 1186 study participants had a mean age of 70.9±5.4 years.The mean dietary oil consumption was 35.0 g/d,being low(<25 g/d),medium(25-49 g/d)and high(≥50 g/d)in 485,467 and 234 participants,respectively.The proportion of the fry or stir-fry cooking style and oils rich in mono-unsaturated fatty acids was 30.4%and 27.4%,respectively.Both before and after adjustment for sex,age,current smoking and alcohol intake,dietary oil consumption was significantly(P≤0.02)and positively associated with the prevalence of treated hypertension and fasting plasma glucose concentration.With similar adjustments as above and additional adjustment for dietary oil consumption,the fry or stir-fry cooking style was significantly(P≤0.048)and positively associated with body mass index,but inversely with systolic and diastolic blood pressure and serum low-density lipoprotein cholesterol,and the dietary intake of oils rich in mono-unsaturated fat acids was significantly(P≤0.02)and positively associated with diastolic blood pressure,serum triglycerides,total cholesterol and low-density lipoprotein cholesterol,and the prevalence of hypertriglyceridemia and hypercholesterolemia.CONCLUSIONS This study showed that both the consumption and composition of fatty acids of the dietary oils mattered with regard to several cardiometabolic measurements in an elderly Chinese population.展开更多
Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-ter...Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-term stability remains challenging.This work reports the oxygen plasma inducing strategy to construct the abundant grain boundaries of Bi/BiO_x on ultrathin two-dimensional Bi nanosheets.The oxygen plasma-treated Bi nanosheet(OP-Bi)exhibits over 90%Faradaic efficiency(FE)for formate at a wide potential range from-0.5 to-1.1 V,and maintains a great stability catalytic performance without significant decay over 30 h in flow cell.Moreover,membrane electrode assembly(MEA)device with OPBi as catalyst sustains the robust current density of 100 mA cm^(-2)over 50 h,maintaining a formate FE above 90%.In addition,rechargeable Zn-CO_(2)battery presents the peak power density of1.22 mW cm^(-2)with OP-Bi as bifunctional catalyst.The mechanism experiments demonstrate that the high-density grain boundaries of OP-Bi provide more exposed active sites,faster electron transfer capacity,and the stronger intrinsic activity of Bi atoms.In situ spectroscopy and theo retical calculations further elucidate that the unsaturated Bi coordination atoms between the grain boundaries can effectively activate CO_(2)molecules through elongating the C-O bond,and reducing the formation energy barrier of the key intermediate(^(*)OCOH),thereby enhancing the catalytic performance of eCO_(2)RR to formate product.展开更多
In order to compare the differences between variations of phosphate ore flotation collectors prepared by hogwash oils, JZQ-F collectors were prepared by the hydrolysis method using four types of hogwash oils from diff...In order to compare the differences between variations of phosphate ore flotation collectors prepared by hogwash oils, JZQ-F collectors were prepared by the hydrolysis method using four types of hogwash oils from different regions in China. The components of the hogwash oils were determined using Fourier transform infrared spectroscopy(FIIR) spectra analysis, while the components of the JZQ-F were determined through gas chromatography–mass spectrometry(GC–MS). The flotation effects of the JZQ-F collectors were investigated by flotation experiments and the adsorption characteristics were determined through the quartz crystal microbalance(QCM-D). Results show that the JZQ-F collector from the Ordos area has 27.43% unsaturated fatty acids. JZQ-F collectors from Beijing, Qingdao, and Dongguan areas contain over 62% of unsaturated fatty acids, which can acquire phosphorous concentrates with a the grade of P_2O_5 above 31.96% and the recovery higher than 91.52%. These three collectors have a larger adsorption capacity, faster adsorption rate, and stronger adsorption structure on apatite surface, which contributed to a good adsorption performance and a favorable flotation effect.展开更多
The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of cat...The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of catalysts, particularly a high content of coordinatively unsaturated Al3+sites(penta-coordinated Al3+,denoted as Al3+penta) could lead to a remarkably improved dehydrogenation activity of the catalyst. The bulk characterization reveals that the sufficient amount of Al3+pentain Al2O3 benefit the dispersion of Pt and Ga2O3 on the Al2O3 support. At the same time, TPR results reveal that the presence of Pt facilitates the reduction of Ga2O3, likely due to the hydrogen spillover between the well dispersed Pt and Ga2O3,which consequently enhances the synergistic function between Pt and Ga2O3 in the dehydrogenation of propane. Recyclability tests demonstrate that the dehydrogenation activity stabilizes after three cycles over the Pt/Ga/Al2O3 catalyst.展开更多
New definition of virtual molecular-group components about CH and CH2 is proposed in the paper.The new reaction,hydrogenation of CH to CH2(HDCH),can be used to represent the change of C and H in RHT.By using the lumpi...New definition of virtual molecular-group components about CH and CH2 is proposed in the paper.The new reaction,hydrogenation of CH to CH2(HDCH),can be used to represent the change of C and H in RHT.By using the lumping approach,the kinetic models about HDCH,HDS,HDN,HDCCR,HDM,HDNi and HDV reactions were established.They are key components of the new kinetic model for RHT based on reaction sections.During the construction of kinetic model,goodness-to-fit(R^2)between test data and model data was set as the target value,and the model parameters were calculated accurately.In verification test,the predicted content of H,S,N,CCR,M,Ni and V can match well with the test data.展开更多
In this study, Raney-Ni/Al_2O_3 catalysts were prepared from precursors which were calcined in different atmosphere(argon and air) and leached for different time. XRD, SEM, H_2-TPR and BET techniques were introduced t...In this study, Raney-Ni/Al_2O_3 catalysts were prepared from precursors which were calcined in different atmosphere(argon and air) and leached for different time. XRD, SEM, H_2-TPR and BET techniques were introduced to characterize the catalysts, and hydrogenation of unsaturated hydrocarbons, including vinyltoluene, dicyclopentadiene and indene, was used as probe reaction to evaluate the catalytic hydrogenation performance of the catalysts. The results demonstrated that the calcination atmosphere had noticeable effects on the compressive strength and hydrogenation performance of Raney-Ni/Al_2O_3. The catalyst calcined in argon exhibited better compressive strength and catalytic performance than the one calcined in air. The compressive strength and activity stability of catalyst were also determined by the leaching time. A too longer leaching time was not conducive to improving the compressive strength and catalytic performance of catalysts. When the precursor calcined in argon was treated in a 15%(by wt.) sodium hydroxide solution at 343 K for 5 h, a catalyst with higher compressive strength(at 26.10 N/mm) was obtained and the conversion of vinyltoluene, dicyclopentadiene(DCPD), and indene could amount to more than 87.5%, 99% and even 100%, respectively, under the reaction conditions covering a temperature of 493 K, a hydrogen pressure of 2.0 MPa, a LSHV of 3.0 h^(-1), and a hydrogen/oil ratio of 200:1.展开更多
Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-ind...Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-index faceted iron oxide(Fe_(2)O_(3))nanocrystals anchored on reduced graphene oxide are developed as highly efficient bifunctional electrocatalysts,effectively improving the electrochemical performance of Li-S batteries.The theoretical and experimental results all indicate that high-index Fe_(2)O_(3)crystal facets with abundant unsaturated coordinated Fe sites not only have strong adsorption capacity to anchor polysulfides but also have high catalytic activity to facilitate the redox transformation of polysulfides and reduce the decomposition energy barrier of Li_(2)S.The Li-S batteries with these bifunctional electrocatalysts exhibit high initial capacity of 1521 mAh g^(-1)at 0.1 C and excellent cycling performance with a low capacity fading of 0.025%per cycle during 1600 cycles at 2 C.Even with a high sulfur loading of 9.41 mg cm^(-2),a remarkable areal capacity of 7.61 mAh cm^(-2)was maintained after 85 cycles.This work provides a new strategy to improve the catalytic activity of nanocrystals through the crystal facet engineering,deepening the comprehending of facet-dependent activity of catalysts in Li-S chemistry,affording a novel perspective for the design of advanced sulfur electrodes.展开更多
Catalytic hydrogenation of furfural to furfuryl alcohol is an important upgrading process for valorization of biomass-derived furanyl platform molecules.However,selective hydrogenation of a,b-unsaturated aldehydes lik...Catalytic hydrogenation of furfural to furfuryl alcohol is an important upgrading process for valorization of biomass-derived furanyl platform molecules.However,selective hydrogenation of a,b-unsaturated aldehydes like furfural to the corresponding alcohols at ambient pressure remains challenging in sustainable chemistry.Till date heterogeneous Au hydrogenation catalyst has been scarcely reported for this reaction due to the low reactivity of Au for H_(2)dissociation.In this work,we showed that Au nanoparticles(loading:0.2 wt%)with a mean size of about 3 nm supported on Cu-doped Al_(2)O_(3)can efficiently hydrogenate furfural to furfuryl alcohol in liquid phase at ambient pressure.We demonstrated that doping a small amount of Cu(2 mol%)to g-Al_(2)O_(3)may modify the Lewis acidity-basicity of Al_(2)O_(3)and simultaneously induce the presence of sufficient Cu^(+) species on surface,which facilitated the hydrogen transfer from i-PrOH to furfural.Moreover,we observed an enhanced reactivity of Au toward molecular H_(2)via cooperation with the Lewis acidic-basic Cu_(2)O-Al_(2)O_(3)support.Hence,100%yield to furfuryl alcohol with a productivity of 0.98 g_(FA),h^(-1),g^(-1)_(cat.)at 120C and 0.1 MPa H_(2)can be obtained.The prepared Au/Cu-Al_(2)O_(3)catalyst was found reusable and was effective to the concentrated furfural solution,as well as several typical unsaturated aldehydes.展开更多
The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characte...The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characteristic curve(SWCC), shrinkage curve, and hydraulic conductivity. The last parameter was determined similar to the Instantaneous Profile Method using evaporation tests. Results indicated that the clay slurry had an air entry value(AEV) of 1000 kPa and a residual suction of 5000 kPa that occurred at the plastic limit and the shrinkage limit, respectively. The discrepancy between theoretical and measured shrinkage limit was due to the gradual increase in clay particle contact. Unlike soils, the saturated hydraulic conductivity varied by two orders of magnitude(4×10 ~10 m/s at 20 kPa to 3 x 10 ~12 m/s at AEV). The unsaturated k further decreased to 10 ~14 m/s at 6 x 10~4 kPa beyond which vapor flow took place.展开更多
The main canal of the Middle Route Project of South-to-North Water Transfer totals more than 1 240 km in length. In Henan Province and Hebei Province, there will be a section of more than 120 km passing through an exp...The main canal of the Middle Route Project of South-to-North Water Transfer totals more than 1 240 km in length. In Henan Province and Hebei Province, there will be a section of more than 120 km passing through an expansive soils area. Expansive soils is a special kind of tenacious clay, which swells when meeting with water and shrinks when losing water. With complicated mechanical properties, it changes with the variation of water content. As a result, expansive soils become the key object of study on unsaturated soils mechanics for the project. From the status of study on unsaturated soils at home and abroad, this paper covers an analysis on stability analysis method of expansive soils slope, determination of expansive soils strength, rational design of canal slope ratio and support, and forecast of landslide for the Middle Route Project of South-to-North Water Transfer.展开更多
基金Project 50239010 supported by the National Natural Science Foundation of China
文摘With the aid of soil column test models,the transport rules of fluorine contaminants in unsaturated stratified soils are discussed. Curves of F-concentrations at different times and sites in the unsaturated stratified soil were ob-tained under conditions of continuous injection of fluoride contaminants and water. Based on the analysis of the actual observation data,the values between computed results and observed data were compared. It is shown that the chemical properties of fluorine ions are active. The migration process of fluorine ions in soils is complex. Because of the effect of adsorption and desorption,the curve of the fluorine ion breakthrough curve is not symmetric. Its concentration peak value at each measuring point gradually decays. The tail of the breakthrough curve is long and the process of leaching and purifying using water requires considerable time. Along with the release of OHˉ in the process of fluorine absorp-tion,the pH value of the soil solution changed from neutral to alkalinity during the test process. The first part of the breakthrough curve fitted better than the second part. The main reason is that fluorine does not always exist in the form of fluorinions in groundwater. Given the long test time,fluorinions possibly react with other ions in the soil solution to form complex water-soluble fluorine compounds. Only the retardation factor and source-sink term have been considered in our numerical model,which may leads to errors of computed values. But as a whole the migration rules of fluorine ions are basically correct,which indicates that the established numerical model can be used to simulate the transport rules of fluorine contaminants in unsaturated stratified soils.
基金Project 50579017 supported by the National Natural Science Foundation of China
文摘The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils,the gas phase and solid phase are relatively insulated,so the average resistivity of soils can be calculated from the resistivity of the liquid phase. On this basis,the two-part model of resistivity changing with the water saturation of the expansive soil can be deduced. A 2-D resistance grid model is established based on simulating the resistance of ver-tically developed fissures. Variation in measured resistance of vertically developed fissures at different positions can be calculated from this model. Fissure development can be inversely determined from the variation in the measured resis-tance. Finally,the model is verified by an indoor resistivity test for remolded soil samples,indicating that the test result agrees well with that of the model established.
基金This research was supported by National Natural Science Foundation of China grants(81971251,81671329,81871050,82171497,82101582,82001406)Clinical Research Center at Shanghai Mental Health Center grants(CRC2018ZD01,CRC2018ZD04,CRC2018YB01,CRC2019ZD02)+6 种基金Clinical Research Center at Shanghai Jiao Tong University School of Medicine(DLY201817,20190102)Shanghai Science and Technology Committee Foundations(19411950800,16ZR1430500,19411969100,19410710800,21ZR1481500,20ZR1448600,21S31903100,19ZR14451)Shanghai Clinical Research Center for Mental Health(19MC1911100)Project of the Key Discipline Construction,Shanghai 3-Year Public Health Action Plan(GWV-10.1-XK18)Shanghai Municipal Science and Technology Major Project(2018SHZDZX01,2018SHZDZX05)and ZJ LabFoundation of Shanghai Mental Health Center(2020-FX-02)Excellent Talents Training Project of Shanghai Municipal Commission of Health(GWV-10.2-YQ44).
文摘Background Disrupted white matter(WM)microstructure has been commonly identified in youth at clinical high risk(CHR)for psychosis.Several lines of evidence suggest that fatty acids,especially unsaturated fatty acids(UFAs),might play a crucial role in the WM pathology of early onset psychosis.However,evidence linking UFA and WM microstructure in CHR is quite sparse.Aims We investigated the relationship between the plasma UFA level and WM microstructure in CHR participants and healthy controls(HC).Methods Plasma fatty acids were assessed and diffusion tensor imaging(DTI)data were performed with tract-based spatial statistics(TBSS)analysis for 66 individuals at CHR for psychosis and 70 HC.Results Both the global and regional diffusion measures showed significant between-group differences,with decreased fractional anisotropy(FA)but increased mean diffusivity(MD)and radial diffusivity(RD)found in the CHR group compared with the HC group.On top of that,we found that in the HC group,plasma arachidic acid showed obvious trend-level associations with higher global FA,lower global MD and lower global RD,which regionally spread over the corpus callosum,right anterior and superior corona radiata,bilateral anterior and posterior limb of the internal capsule,and bilateral superior longitudinal fasciculus.However,there were no associations between global WM measures and any UFA in the CHR group.Conversely,we even found negative associations between arachidic acid levels and regional FA values in the right superior longitudinal fasciculus and right retrolenticular part of the internal capsule in the CHR group.Conclusions Compared with the HC group,CHR subjects exhibited a different pattern of association between WM microstructure and plasma UFA,with a neuroprotective effect found in the HC group but not in the CHR group.Such discrepancy could be due to the excessively upregulated UFAs accumulated in the plasma of the CHR group,highlighting the role of balanced plasma-membrane fatty acids homeostasis in WM development.
文摘The stability of unsaturated soil slope has been the hot point recently. Especially, the seeping rainfall makes losing stability of unsaturated soil slope, and causes enormous loss to the producation and safety of other people. The seeping rainfall makes volumetric water content of unsaturated soil slope changing, and the volumetric water content has directly relationship with matric suction. And matric suction also has directly relationship with the stability of unsaturated soil slope. So the change of matric suction influence the stability changing, that is, safety coefficient has decided relationship with volumetric water content. The profile of dangerous volumetric water content curves of unsaturated soil slope has been obtained. If a volumetric water content curve of some unsaturated soil slope belongs to one of these dongerous curves, the unsaturated soil slope could be in danger. So this is called DVWCCP(dangerous volumetric water content curves profile). By monitoring the volumetric water content curves can obtain the stability information of some soil slope to serve producing and safety.
文摘The 7th international conference on unsaturated soils（3rd–5th August 2018）is organised by the Hong Kong University of Science and Technology and supported by：TC106 Unsaturated Soils of ISSMGE;Hong Kong Geotechnical Society;Geotechnical Division of Hong Kong Institution of Engineers;
基金supported by the 13th Five-Year National Key Research and Development Plan of China (2016YFD0300609)the Outstanding Science and Technology Innovation Talents Program of Henan province (184200510008)+4 种基金Modern Agricultural Technology System Project of Henan Province (S2010-01G04)the National Key Research and Development Program of China (2017YFD0301105)the National Natural Science Foundations of CHINA (Grant No. 61501373, No. 61771390, No. 61771392, No. 61871322, and No. 61271279)the Henan Province Key Scientific and Technological Project (182102110291 and 222102110234)Natural Science Foundation of Henan Province (232300420186)
文摘In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies in the next generation WLAN communication standards.However,the performance of the existing media access control(MAC)degrades significantly under unsaturated services.Therefore,this paper proposes a multi-user parallel contention channel MAC(MU-MAC)based on unsaturated services,which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On this basis,MU-MAC is enhanced for the spatial clustering group(SCG)formation protocol and support for the unsaturated service characteristics.Further,the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally,and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72%and 104.15%,respectively.
基金supported by National Natural Science Foundation of China under Grant No.60772085, 61071108Sino-Finland Joint Project under Grant No.2010DFB10570China Fundamental Research Funds for the Central Universities under Grant No.SWJTU 09ZT14
文摘This paper proposes an analysis model of frame aggregation in error-free channel with unsaturated traffic and fixed aggregation size. Integrated with model of channel access, calculation of MAC (Media Access Control) average service time and queue model of frame aggregation, our model can get the stable result with a recursive algorithm, and it further derive the throughput and latency of frame aggregation in steady state. As the impact of traffic, frame length, collision probability, buffer size, aggregation size and interactive effects are taken into consideration, the effect of every parameter could be evaluated and the major factor which degrades the performance of frame aggregation can be determined in different situation with this model. By the simulation and numerical analysis, this model confirmed its accuracy. The proposed model can be used in the design, optimization and deployment of WLAN (Wireless Local Area Network) and WMN (Wireless Mesh Network) widely.
基金This work was supported in part by the Natural Science Foundation of China under Grant 61725103,Grant 91638202,Grant 61801361 and Grant U19B2025,and was supported by“the Fundamental Research Funds for the Central Universities”.
文摘Scheduling schemes assign limited resources to appropriate users,which are critical for wireless network performance.Most current schemes have been designed based on saturated traffic,i.e.,assuming users in networks always have data to transmit.However,the user buffer may sometimes be empty in actual network.Therefore,these algorithms will allocate resources to users having no data to transmit,which results in resource waste.In view of this,we propose new scheduling schemes for onehop and two-hop link scenario with unsaturated traffic.Furthermore,this paper analyzes their key network performance indicators,including the average queue length,average throughput,average delay and outage probability.The two scheduling algorithms avoid scheduling the links whose buffers are empty and thus improve the network resource utilization.For the one-hop link scenario,network provides differentiated services via adjusting the scheduling probabilities of the destination nodes(DNs)with different priorities.Among the DNs with same priority,the node with higher data arrival rate has larger scheduling probability.For the two-hop link scenario,we prioritize the scheduling of relay-to-destination(R-D)link and dynamically adjust the transmission probability of source-to-relay(S-R)link,according to the length of remaining buffer.The experiment results show the effectiveness and advantage of the proposed algorithms.
文摘Leaching is widely applied in the exploitation of depleted ores. In order to discover the law of leachant movement in the leaching process and calculating volumes and time intervals of spraying leachant,experiments and numerical simulation with the TOUGH2/EOS3 module were carried out in order to find out the principle of water movement in unsaturated copper ore. The results show that water volume increases at the same location over time,that copper ore tends to become saturated and that liquid velocity decreases at the same time as the distance from top in-creases. On the other hand,a comparison and analysis of our experimental and simulated results indicate that the EOS3 module could accurately simulate the water movement in an unsaturated state.
文摘The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, four treatment schemes were tried. Na 2CO 3 could reduce conspicuously the permeability of the saturated clay, but could not limit the permeability rise in the alternate wetting and drying process. NaOH had a similar effect to Na 2CO 3. NaCl could not only decrease the saturated hydraulic conductivity, but could also effectively contain the permeability rise caused by evaporation. CH 3COONa had a similar effect to NaCl. The mechanism of Na 2CO 3, NaOH, NaCl and CH 3COONa decreasing the saturated hydraulic conductivity of the clay is that Na + transformed Ca montmorillonites in the original clay into Na montmorillonites and the transformation reduces the sizes of effective pores and the effective porosity of the clay.
基金supported by the National Natural Science Foundation of China (No.82070432 & No.82070435 & No.82270469 & No.82370426)the Ministry of Science and Technology, Beijing, China (2018YFC1704902 & 2022YFC3601302)+3 种基金the Shanghai Commissions of Science and Technology and Health (a special grant for “leading academics”) (No.19DZ2340200)the Three-year Action Program of Shanghai Municipality for Strengthening the Construction of Public Health System Big Data and Artificial Intelligence Application, Shanghai, China (GWV10.1-XK05)research grants from A&D, Bayer, Omron, Salubris, and Shyndeclecture fees from A& D, Novartis, Omron, Servier, Salubris and Shyndec
文摘OBJECTIVE To investigate three features of dietary cooking oil intake,namely,the consumption,cooking style,and composition of fatty acids in relation to several cardiometabolic measurements in an elderly Chinese population.METHODS The elderly(≥65 years)participants for this study were recruited from two community health centers in the urban area of Shanghai.A questionnaire was administered to collect information on dietary oil consumption(low,medium and high)and cooking styles(fry or stir-fry vs.others)and the composition of fatty acids(poly-unsaturated vs.mono-unsaturated).The cardiometabolic measurements included anthropometry,blood pressure,fasting plasma glucose and serum lipids.RESULTS The 1186 study participants had a mean age of 70.9±5.4 years.The mean dietary oil consumption was 35.0 g/d,being low(<25 g/d),medium(25-49 g/d)and high(≥50 g/d)in 485,467 and 234 participants,respectively.The proportion of the fry or stir-fry cooking style and oils rich in mono-unsaturated fatty acids was 30.4%and 27.4%,respectively.Both before and after adjustment for sex,age,current smoking and alcohol intake,dietary oil consumption was significantly(P≤0.02)and positively associated with the prevalence of treated hypertension and fasting plasma glucose concentration.With similar adjustments as above and additional adjustment for dietary oil consumption,the fry or stir-fry cooking style was significantly(P≤0.048)and positively associated with body mass index,but inversely with systolic and diastolic blood pressure and serum low-density lipoprotein cholesterol,and the dietary intake of oils rich in mono-unsaturated fat acids was significantly(P≤0.02)and positively associated with diastolic blood pressure,serum triglycerides,total cholesterol and low-density lipoprotein cholesterol,and the prevalence of hypertriglyceridemia and hypercholesterolemia.CONCLUSIONS This study showed that both the consumption and composition of fatty acids of the dietary oils mattered with regard to several cardiometabolic measurements in an elderly Chinese population.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2024SHFZ074,ZDYF2024SHFZ072,ZDYF2022SHFZ299)the National Natural Science Foundation of China(22109035,22202053,52164028,52274297,22309037)+4 种基金the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,21125,23035)the collaborative Innovation Center of Marine Science and Technology,Hainan University(XTCX2022HYC04,XTCX2022HYC05)the Innovative Research Projects for Graduate Students of Hainan Province(Qhyb2022-89,Qhyb2022-87,Qhys2022-174)the Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.23JK0439)the specific research fund of The Innovation Platform for Academicians of Hainan Province(YSPTZX202315)。
文摘Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-term stability remains challenging.This work reports the oxygen plasma inducing strategy to construct the abundant grain boundaries of Bi/BiO_x on ultrathin two-dimensional Bi nanosheets.The oxygen plasma-treated Bi nanosheet(OP-Bi)exhibits over 90%Faradaic efficiency(FE)for formate at a wide potential range from-0.5 to-1.1 V,and maintains a great stability catalytic performance without significant decay over 30 h in flow cell.Moreover,membrane electrode assembly(MEA)device with OPBi as catalyst sustains the robust current density of 100 mA cm^(-2)over 50 h,maintaining a formate FE above 90%.In addition,rechargeable Zn-CO_(2)battery presents the peak power density of1.22 mW cm^(-2)with OP-Bi as bifunctional catalyst.The mechanism experiments demonstrate that the high-density grain boundaries of OP-Bi provide more exposed active sites,faster electron transfer capacity,and the stronger intrinsic activity of Bi atoms.In situ spectroscopy and theo retical calculations further elucidate that the unsaturated Bi coordination atoms between the grain boundaries can effectively activate CO_(2)molecules through elongating the C-O bond,and reducing the formation energy barrier of the key intermediate(^(*)OCOH),thereby enhancing the catalytic performance of eCO_(2)RR to formate product.
文摘In order to compare the differences between variations of phosphate ore flotation collectors prepared by hogwash oils, JZQ-F collectors were prepared by the hydrolysis method using four types of hogwash oils from different regions in China. The components of the hogwash oils were determined using Fourier transform infrared spectroscopy(FIIR) spectra analysis, while the components of the JZQ-F were determined through gas chromatography–mass spectrometry(GC–MS). The flotation effects of the JZQ-F collectors were investigated by flotation experiments and the adsorption characteristics were determined through the quartz crystal microbalance(QCM-D). Results show that the JZQ-F collector from the Ordos area has 27.43% unsaturated fatty acids. JZQ-F collectors from Beijing, Qingdao, and Dongguan areas contain over 62% of unsaturated fatty acids, which can acquire phosphorous concentrates with a the grade of P_2O_5 above 31.96% and the recovery higher than 91.52%. These three collectors have a larger adsorption capacity, faster adsorption rate, and stronger adsorption structure on apatite surface, which contributed to a good adsorption performance and a favorable flotation effect.
基金the National Natural Science Foundation of China(No.21676195)the China Postdoctoral Science Foundation(2016M601347)。
文摘The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of catalysts, particularly a high content of coordinatively unsaturated Al3+sites(penta-coordinated Al3+,denoted as Al3+penta) could lead to a remarkably improved dehydrogenation activity of the catalyst. The bulk characterization reveals that the sufficient amount of Al3+pentain Al2O3 benefit the dispersion of Pt and Ga2O3 on the Al2O3 support. At the same time, TPR results reveal that the presence of Pt facilitates the reduction of Ga2O3, likely due to the hydrogen spillover between the well dispersed Pt and Ga2O3,which consequently enhances the synergistic function between Pt and Ga2O3 in the dehydrogenation of propane. Recyclability tests demonstrate that the dehydrogenation activity stabilizes after three cycles over the Pt/Ga/Al2O3 catalyst.
基金financially supported by the SINOPEC Research Program(Grant KL20009 and 118015-2)。
文摘New definition of virtual molecular-group components about CH and CH2 is proposed in the paper.The new reaction,hydrogenation of CH to CH2(HDCH),can be used to represent the change of C and H in RHT.By using the lumping approach,the kinetic models about HDCH,HDS,HDN,HDCCR,HDM,HDNi and HDV reactions were established.They are key components of the new kinetic model for RHT based on reaction sections.During the construction of kinetic model,goodness-to-fit(R^2)between test data and model data was set as the target value,and the model parameters were calculated accurately.In verification test,the predicted content of H,S,N,CCR,M,Ni and V can match well with the test data.
基金the Beijing Municipal Commission of Education for funding (PXM2013-014222)
文摘In this study, Raney-Ni/Al_2O_3 catalysts were prepared from precursors which were calcined in different atmosphere(argon and air) and leached for different time. XRD, SEM, H_2-TPR and BET techniques were introduced to characterize the catalysts, and hydrogenation of unsaturated hydrocarbons, including vinyltoluene, dicyclopentadiene and indene, was used as probe reaction to evaluate the catalytic hydrogenation performance of the catalysts. The results demonstrated that the calcination atmosphere had noticeable effects on the compressive strength and hydrogenation performance of Raney-Ni/Al_2O_3. The catalyst calcined in argon exhibited better compressive strength and catalytic performance than the one calcined in air. The compressive strength and activity stability of catalyst were also determined by the leaching time. A too longer leaching time was not conducive to improving the compressive strength and catalytic performance of catalysts. When the precursor calcined in argon was treated in a 15%(by wt.) sodium hydroxide solution at 343 K for 5 h, a catalyst with higher compressive strength(at 26.10 N/mm) was obtained and the conversion of vinyltoluene, dicyclopentadiene(DCPD), and indene could amount to more than 87.5%, 99% and even 100%, respectively, under the reaction conditions covering a temperature of 493 K, a hydrogen pressure of 2.0 MPa, a LSHV of 3.0 h^(-1), and a hydrogen/oil ratio of 200:1.
基金This work was supported by the National Natural Science Foundation of China(No.22078078)the Natural Science Foundation of Heilongjiang Province(No.LH2020B008)the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.2019DX13).
文摘Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-index faceted iron oxide(Fe_(2)O_(3))nanocrystals anchored on reduced graphene oxide are developed as highly efficient bifunctional electrocatalysts,effectively improving the electrochemical performance of Li-S batteries.The theoretical and experimental results all indicate that high-index Fe_(2)O_(3)crystal facets with abundant unsaturated coordinated Fe sites not only have strong adsorption capacity to anchor polysulfides but also have high catalytic activity to facilitate the redox transformation of polysulfides and reduce the decomposition energy barrier of Li_(2)S.The Li-S batteries with these bifunctional electrocatalysts exhibit high initial capacity of 1521 mAh g^(-1)at 0.1 C and excellent cycling performance with a low capacity fading of 0.025%per cycle during 1600 cycles at 2 C.Even with a high sulfur loading of 9.41 mg cm^(-2),a remarkable areal capacity of 7.61 mAh cm^(-2)was maintained after 85 cycles.This work provides a new strategy to improve the catalytic activity of nanocrystals through the crystal facet engineering,deepening the comprehending of facet-dependent activity of catalysts in Li-S chemistry,affording a novel perspective for the design of advanced sulfur electrodes.
基金supported by National Natural Science Foundation of China(21603187,21763031,22062025)National Special Funds of China(C176220100063)Program for Excellent Young Talents of Yunnan University,Yunnan Fundamental Research Projects(202001AW070012)。
文摘Catalytic hydrogenation of furfural to furfuryl alcohol is an important upgrading process for valorization of biomass-derived furanyl platform molecules.However,selective hydrogenation of a,b-unsaturated aldehydes like furfural to the corresponding alcohols at ambient pressure remains challenging in sustainable chemistry.Till date heterogeneous Au hydrogenation catalyst has been scarcely reported for this reaction due to the low reactivity of Au for H_(2)dissociation.In this work,we showed that Au nanoparticles(loading:0.2 wt%)with a mean size of about 3 nm supported on Cu-doped Al_(2)O_(3)can efficiently hydrogenate furfural to furfuryl alcohol in liquid phase at ambient pressure.We demonstrated that doping a small amount of Cu(2 mol%)to g-Al_(2)O_(3)may modify the Lewis acidity-basicity of Al_(2)O_(3)and simultaneously induce the presence of sufficient Cu^(+) species on surface,which facilitated the hydrogen transfer from i-PrOH to furfural.Moreover,we observed an enhanced reactivity of Au toward molecular H_(2)via cooperation with the Lewis acidic-basic Cu_(2)O-Al_(2)O_(3)support.Hence,100%yield to furfuryl alcohol with a productivity of 0.98 g_(FA),h^(-1),g^(-1)_(cat.)at 120C and 0.1 MPa H_(2)can be obtained.The prepared Au/Cu-Al_(2)O_(3)catalyst was found reusable and was effective to the concentrated furfural solution,as well as several typical unsaturated aldehydes.
基金the Natural Sciences and Engineering Research Council of Canada for providing financial assistance
文摘The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characteristic curve(SWCC), shrinkage curve, and hydraulic conductivity. The last parameter was determined similar to the Instantaneous Profile Method using evaporation tests. Results indicated that the clay slurry had an air entry value(AEV) of 1000 kPa and a residual suction of 5000 kPa that occurred at the plastic limit and the shrinkage limit, respectively. The discrepancy between theoretical and measured shrinkage limit was due to the gradual increase in clay particle contact. Unlike soils, the saturated hydraulic conductivity varied by two orders of magnitude(4×10 ~10 m/s at 20 kPa to 3 x 10 ~12 m/s at AEV). The unsaturated k further decreased to 10 ~14 m/s at 6 x 10~4 kPa beyond which vapor flow took place.
文摘The main canal of the Middle Route Project of South-to-North Water Transfer totals more than 1 240 km in length. In Henan Province and Hebei Province, there will be a section of more than 120 km passing through an expansive soils area. Expansive soils is a special kind of tenacious clay, which swells when meeting with water and shrinks when losing water. With complicated mechanical properties, it changes with the variation of water content. As a result, expansive soils become the key object of study on unsaturated soils mechanics for the project. From the status of study on unsaturated soils at home and abroad, this paper covers an analysis on stability analysis method of expansive soils slope, determination of expansive soils strength, rational design of canal slope ratio and support, and forecast of landslide for the Middle Route Project of South-to-North Water Transfer.
