The high efficient eco-agricultural zone in Eco-economic Region of Poyang Lake was divided into three different areas. 12 indicators including per capita cultivated land,forest coverage,comprehensive utilization rate ...The high efficient eco-agricultural zone in Eco-economic Region of Poyang Lake was divided into three different areas. 12 indicators including per capita cultivated land,forest coverage,comprehensive utilization rate of straw,the ratio of the effective irrigation area to the arable land,amount of pesticide usage per unit area of arable land,the output value ratio of planting industry,the output value ratio of forestry and fruit industry,the output value ratio of stock farming,the output value ratio of fishery,the proportion of sown area of crop,proportion of sown area of oil plants and the proportion of sown area of vegetable were screened to construct the indicator system of regionalization of high efficient eco-agriculture. The average index values of the high efficient eco-agricultural regionalization of three regions were obtained,the development direction of the efficient eco-agriculture construction of three areas were analyzed according to the natural resources characteristics f eco-agricultural and requirements of high efficient eco-agricultural development of the regions.展开更多
To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine...To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array(CGA) was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan(YS) lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction(68.89%) during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.展开更多
Establishment of a highly efficient regeneration system for the mature embryo of wheat will provide a convenient tool for wheat tissue culture and transformation, thereby facilitating the transformation of foreign gen...Establishment of a highly efficient regeneration system for the mature embryo of wheat will provide a convenient tool for wheat tissue culture and transformation, thereby facilitating the transformation of foreign genes into wheat. By using the mature embryos derived from 20 different wheat lines including Shi 4185, Yumai 66, Lunxuan 987, CB037, Yangmai 6, Xinchun 9, Bobwhite, Han 6172, Zheng 9023, Jimai 20, Ningchun 4, and Jing 411, the effects of some factors including inoculation methods, initiating culture media, organic additives, antioxidants, and auxins on the regeneration from the explants were evaluated. The results indicated that the scraping embryo culture was better than the whole embryo culture, the Aa medium was better than the SD2 medium and dicamba was better than 2,4-D in increasing the regeneration frequency. An Adi medium was established in this study by adding silver nitrate, cysteine, ascorbic acid, dicamba, glutamine into the Aa medium at the concentration of 4,40, 100, 2, and 5 mg L^-1, respectively. By using the Adi medium and the scraping technique, the regeneration frequencies of the mature embryos of CB037, Lunxuan 987, Hart 6172, Yangmai 6, Bobwhite, Zheng 9023, Shi 4 185, and Jimai 20 became 85.6, 60,1, 46.0, 42.1,42.0, 34.0, 33.0, and 32.0%, respectively, which were about 5-8 times higher than that obtained from the conventional culture mediums and techniques. This novel regeneration system could be helpful in wheat transformation.展开更多
Content-based 3D model retrieval is of great help to facilitate the reuse of existing designs and to inspire designers during conceptual design. However, there is still a gap to apply it in industry due to the low tim...Content-based 3D model retrieval is of great help to facilitate the reuse of existing designs and to inspire designers during conceptual design. However, there is still a gap to apply it in industry due to the low time efficiency. This paper presents two new methods with high efficiency to build a Content-based 3D model retrieval system. First, an improvement is made on the "Shape Distribution (D2)" algorithm, and a new algorithm named "Quick D2" is proposed. Four sample 3D mechanical models are used in an experiment to compare the time cost of the two algorithms. The result indicates that the time cost of Quick D2 is much lower than that of D2, while the descriptors extracted by the two algorithms are almost the same. Second, an expandable 3D model repository index method with high performance, namely, RBK index, is presented. On the basis of RBK index, the search space is pruned effectively during the search process, leading to a speed up of the whole system. The factors that influence the values of the key parameters of RBK index are discussed and an experimental method to find the optimal values of the key parameters is given. Finally, "3D Searcher", a content-based 3D model retrieval system is developed. By using the methods proposed, the time cost for the system to respond one query online is reduced by 75% on average. The system has been implemented in a manufacturing enterprise, and practical query examples during a case of the automobile rear axle design are also shown. The research method presented shows a new research perspective and can effectively improve the content-based 3D model retrieval efficiency.展开更多
An easily stackable multi-layer quasi-zero-stiffness(ML-QZS)meta-structure is proposed to achieve highly efficient vibration isolation performance at low frequency.First,the distributed shape optimization method is us...An easily stackable multi-layer quasi-zero-stiffness(ML-QZS)meta-structure is proposed to achieve highly efficient vibration isolation performance at low frequency.First,the distributed shape optimization method is used to design the unit cel,i.e.,the single-layer QZS(SL-QZS)meta-structure.Second,the stiffness feature of the unit cell is investigated and verified through static experiments.Third,the unit cells are stacked one by one along the direction of vibration isolation,and thus the ML-QZS meta-structure is constructed.Fourth,the dynamic modeling of the ML-QZS vibration isolation metastructure is conducted,and the dynamic responses are obtained from the equations of motion,and verified by finite element(FE)simulations.Finally,a prototype of the ML-QZS vibration isolation meta-structure is fabricated by additive manufacturing,and the vibration isolation performance is evaluated experimentally.The results show that the vibration isolation performance substantially enhances when the number of unit cells increases.More importantly,the ML-QZS meta-structure can be easily extended in the direction of vibration isolation when the unit cells are properly stacked.Hence,the ML-FQZS vibration isolation meta-structure should be a fascinating solution for highly efficient vibration isolation performance at low frequency.展开更多
Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,lim...Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.展开更多
Experimental methods,including mercury pressure,nuclear magnetic resonance(NMR)and core(wateroil)displacement,are used to examine the effects of high-multiple water injection(i.e.water injection with high injected por...Experimental methods,including mercury pressure,nuclear magnetic resonance(NMR)and core(wateroil)displacement,are used to examine the effects of high-multiple water injection(i.e.water injection with high injected pore volume)on rock properties,pore structure and oil displacement efficiency of an oilfield in the western South China Sea.The results show an increase in the permeability of rocks along with particle migration,an increase in the pore volume and the average pore throat radius,and enhanced heterogeneity after high-multiple water injection.Compared with normal water injection methods,a high-multiple water injection is more effective in improving the oil displacement efficiency.The degree of recovery increases faster in the early stage due to the expansion of the swept area,and the transition from oil-wet to water-wet.The degree of recovery increases less in the late stage due to various factors,including the enhancement of heterogeneity in the rocks.Considering both the economic aspect and the production limit of water flooding,it is recommended to adopt other technologies to further enhance oil recovery after 300 PV water injection.展开更多
The deferred correction(DeC)is an iterative procedure,characterized by increasing the accuracy at each iteration,which can be used to design numerical methods for systems of ODEs.The main advantage of such framework i...The deferred correction(DeC)is an iterative procedure,characterized by increasing the accuracy at each iteration,which can be used to design numerical methods for systems of ODEs.The main advantage of such framework is the automatic way of getting arbitrarily high order methods,which can be put in the Runge-Kutta(RK)form.The drawback is the larger computational cost with respect to the most used RK methods.To reduce such cost,in an explicit setting,we propose an efcient modifcation:we introduce interpolation processes between the DeC iterations,decreasing the computational cost associated to the low order ones.We provide the Butcher tableaux of the new modifed methods and we study their stability,showing that in some cases the computational advantage does not afect the stability.The fexibility of the novel modifcation allows nontrivial applications to PDEs and construction of adaptive methods.The good performances of the introduced methods are broadly tested on several benchmarks both in ODE and PDE contexts.展开更多
Based on reserve abundance,large gas fields in China can be divided into two types:type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,domina...Based on reserve abundance,large gas fields in China can be divided into two types:type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,dominated by stratigraphic and lithologic gas reservoirs.The formation of these two types of large gas fields is related to the highly efficient accumulation of natural gas.The accumulation of high abundance gas fields is dependent on the rapid maturation of the source kitchen and huge residual pressure difference between the gas source kitchen and reservoir,which is the strong driving force for natural gas migration to traps.Whereas the accumulation of low abundance gas fields is more complicated,involving both volume flow charge during the burial stage and diffusion flow charge during the uplift stage,which results in large area accumulation and preservation of natural gas in low porosity and low permeability reservoirs.This conclusion should assist gas exploration in different geological settings.展开更多
Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the ...Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage(VOC) and power conversion efficiency(PCE). Lithium chloride(Li Cl) was added into the tin oxide(SnO_(2)) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer(ETL)/perovskite interface.Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and V_(OC) of 1.92 V, which is the highest PCE and VOCin N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.展开更多
A cyclometalated greenish-yellow emitter 2,3-diphenylimidazo[1,2-a]pyridine iridium(Ill) complex is successfully synthesized and used to fabricate phosphorescent organic light-emitting diodes. The optimized device e...A cyclometalated greenish-yellow emitter 2,3-diphenylimidazo[1,2-a]pyridine iridium(Ill) complex is successfully synthesized and used to fabricate phosphorescent organic light-emitting diodes. The optimized device exhibits a greenish-yellow emission with the peak at 523nm and a strong shoulder at 557nm, corresponding to Commission Internationale de l'Eclairage coordinates of (0.38, 0.68). The full width at half maximum of the device is 93 nm, which is broader than the fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] based reference device of 78 nm. Meanwhile, a maximum current efficiency of 62.6 cd/A (47.51m/W) is obtained. This result is higher than a maximum current efficiency of 54.8 cd/A (431m/W) of the Ir(ppy)a based device. The results indicate that this new iridium complex may have potential applications in fabricating high color rendering index white organic light emitting diodes.展开更多
The bottleneck of strontium compounds preparing from celestite is the promotion of Sr/S isolation efficiency.Low energy consumption and zero release method for isolating Sr/S in preparing Sr(OH)2 process from celestit...The bottleneck of strontium compounds preparing from celestite is the promotion of Sr/S isolation efficiency.Low energy consumption and zero release method for isolating Sr/S in preparing Sr(OH)2 process from celestite in mild condition was described.Sr element remained in precipitation with formation of Sr(OH)2,while S element entered into leachate with formation of Na2SO4.The effects of initial concentration of NaOH,conversion temperature,liquid-to-solid(L/S)ratio and conversion time on Sr/S ratio of samples for celestite conversion were systematically investigated by experiments.The results demonstrated that the efficiency of Sr/S isolation increased with the initial concentration of NaOH,L/S ratio and conversion time,and decreased with conversion temperature.The maximum conversion ratio of Sr(OH)2 was 93.88%under the optimum condition,whose Sr/S ratio of sample could reach to 41.16.It illustrated that better isolation efficiency of celestite could be achieved in alkaline treatment.The results of SEM-EDS analyses demonstrated that the conversion reaction was a dissolution-precipitation process.展开更多
Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9...Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus(SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif(PAM) that the canonical Streptococcus pyogenes Cas9(SpCas9) or its variants(e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor(SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.展开更多
A distinctive method is proposed by simply utilizing ultrasonic technique in Ti02 electrode fabrication in order to improve the optoelectronic performance of dye-sensitized solar cells (DSSCs). Dye molecules are at ...A distinctive method is proposed by simply utilizing ultrasonic technique in Ti02 electrode fabrication in order to improve the optoelectronic performance of dye-sensitized solar cells (DSSCs). Dye molecules are at random and single molecular state in the ultrasonic field and the ultrasonic wave favors the diffusion and adsorption processes of dye molecules. As a result, the introduction of ultrasonic technique at room temperature leads to faster and more well-distributed dye adsorption on TiO2 as well as higher cell efficiency than regular deposition, thus the fabrication time is markedly reduced. It is found that the device based on 40 kHz ultrasonic (within 1 h) with N719 exhibits a Voc of 789 mV, Jsc of 14.94 mA]cm2 and fill factor (FF) of 69.3, yielding power conversion efficiency (PCE) of 8.16%, which is higher than device regularly dyed for 12 h (PCE = 8.06%). In addition, the DSSC devices obtain the best efficiency (PCE = 8.68%) when the ultrasonic deposition time increases to 2.5 h. The DSSCs fabricated via ultrasonic technique presents more dye loading, larger photocurrent, less charge recombination and higher photovoltage. The charge extraction and electron impedance spectroscopy (EIS) were performed to understand the influence of ultrasonic technique on the electron recombination and performance of DSSCs.展开更多
A highly efficient and convenient procedure for the enantioselective synthesis of (S)-Rivastigmine, a cholinergic agent for the treatment of mild to moderate dementia of the Alzheimer’s type and dementia due to Parki...A highly efficient and convenient procedure for the enantioselective synthesis of (S)-Rivastigmine, a cholinergic agent for the treatment of mild to moderate dementia of the Alzheimer’s type and dementia due to Parkinson’s disease, is accomplished by the treatment of versatile, readily accessible (S)-(-)-2-methyl-2-propanesulfinamide with 3-hydroxyacetophenone. This protocol provides high yield and excellent enantiomeric excess in short step synthesis.展开更多
Interfacial layer has a significant impact on the achievement of highly efficient organic–inorganic hybrid perovskite solar cells(PSCs). Here, we introduced a nano-ZnMgO(magnesium doped ZnO, abbreviated as ZnMgO) as ...Interfacial layer has a significant impact on the achievement of highly efficient organic–inorganic hybrid perovskite solar cells(PSCs). Here, we introduced a nano-ZnMgO(magnesium doped ZnO, abbreviated as ZnMgO) as interfacial layer between [6, 6]-Phenyl C_(61) butyric acid methyl ester(PC_(61) BM) layer and Al electrode to replace LiF or ZnO interlayer and enhance device performance. The device efficiency has been improved from 11.43% to 15.61% and the hysteresis was decreased dramatically. Such huge enhancement of power convert efficiency(PCE) can be attributed to the low dark current density, enhancement of electron-selective contact, and low energy barrier at the PC_(61) BM/Al interface. We suggest that this simple nano-scale interlayer can provide an efficient charge transport and extraction for highly efficient PSCs.展开更多
Li-rich Mn-based oxides(LRMOs)hold great promise as next-generation cathode materials for high-energy Li-ion batteries because of their low cost and high capacity.Nevertheless,the practical application of LRMOs is imp...Li-rich Mn-based oxides(LRMOs)hold great promise as next-generation cathode materials for high-energy Li-ion batteries because of their low cost and high capacity.Nevertheless,the practical application of LRMOs is impeded by their low initial Coulombic efficiency and rapid voltage decay.Herein,a V-doped layered-spinel coherent layer is constructed on the surface of a Co-free LRMO through a simple treatment with NH_(4)VO_(3).The layered-spinel coherent layer with 3D ion channels enhanced Li+diffusion efficiency,mitigates surface-inter-face reactions and suppresses irreversible oxygen release.Notably,V-doping significantly reduces the Bader charge of oxygen atoms,thereby impeding excessive oxidation of oxygen ions and further enhancing the stability of O-redox.The modified LRMO exhibites a remarkable initial Coulombic efficiency of 91.6%,signifi-cantly surpassing that of the original LRMO(74.4%).Furthermore,the treated sample showes an impressive capacity retention rate of 91.9%after 200 cycles,accompanied by a voltage decay of merely 0.47 mV per cycle.The proposed treatment approach is straightforward and significantly improves the initial Coulombic efficiency,voltage stability,and capacity stability of LRMO cathode materials,thus holding considerable promise for the development of high-energy Li-ion batteries.展开更多
Based on the current problems in carrot production,Laixi City of Shandong Province adopted 5 m large arch shed double-layer plastic film to cultivate " Three Red" carrot,selected varieties suitable for expor...Based on the current problems in carrot production,Laixi City of Shandong Province adopted 5 m large arch shed double-layer plastic film to cultivate " Three Red" carrot,selected varieties suitable for export,ridging double-row mechanical drilling,integrated water and fertilizer management,carrot residue composting and returning to field,and finally realized safe and high efficient production of facility carrot industrialization.展开更多
On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from s...On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from secondary resources of low-grade metals by adding iron oxide as the trapping agent, reducing agent, additive, mixing uniformly and grinding, pelletizing, reduction, grinding and separation, and selectively acid leaching iron has been put forward in this paper. The experiments of reduction, grinding and separation, and selectively acid leaching iron were carried out mainly. Under the decided experiment parameters and conditions, iron generated during the reduction can trap precious metals during reduction, high active alloy powders were obtained from the reduced products by grinding and separation, the concentration of precious metals was obtained by acid leaching high active alloy powders. The better enrichment effect was obtained by adopting the technical route of processing. Other low grade noble metal materials and enrichment ratio of precious metals from the materials to acid products was high through acid leaching. This process has the advantages of simple process, environmental-friendly, strong adaptability of raw materials, high concentration ratio, which was regarded as a kind of the general efficient enrichment technology of low grade precious metal materials.展开更多
文摘The high efficient eco-agricultural zone in Eco-economic Region of Poyang Lake was divided into three different areas. 12 indicators including per capita cultivated land,forest coverage,comprehensive utilization rate of straw,the ratio of the effective irrigation area to the arable land,amount of pesticide usage per unit area of arable land,the output value ratio of planting industry,the output value ratio of forestry and fruit industry,the output value ratio of stock farming,the output value ratio of fishery,the proportion of sown area of crop,proportion of sown area of oil plants and the proportion of sown area of vegetable were screened to construct the indicator system of regionalization of high efficient eco-agriculture. The average index values of the high efficient eco-agricultural regionalization of three regions were obtained,the development direction of the efficient eco-agriculture construction of three areas were analyzed according to the natural resources characteristics f eco-agricultural and requirements of high efficient eco-agricultural development of the regions.
基金Project(50774102)supported by the National Natural Science Foundation of ChinaProject(2004CB619204)supported by the National Basic Research Program of China
文摘To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array(CGA) was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan(YS) lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction(68.89%) during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.
基金funded by the National Natural Science Foundation of China (30971776)the National Transgenic Organism Research Program of China(2008ZX08010-004)
文摘Establishment of a highly efficient regeneration system for the mature embryo of wheat will provide a convenient tool for wheat tissue culture and transformation, thereby facilitating the transformation of foreign genes into wheat. By using the mature embryos derived from 20 different wheat lines including Shi 4185, Yumai 66, Lunxuan 987, CB037, Yangmai 6, Xinchun 9, Bobwhite, Han 6172, Zheng 9023, Jimai 20, Ningchun 4, and Jing 411, the effects of some factors including inoculation methods, initiating culture media, organic additives, antioxidants, and auxins on the regeneration from the explants were evaluated. The results indicated that the scraping embryo culture was better than the whole embryo culture, the Aa medium was better than the SD2 medium and dicamba was better than 2,4-D in increasing the regeneration frequency. An Adi medium was established in this study by adding silver nitrate, cysteine, ascorbic acid, dicamba, glutamine into the Aa medium at the concentration of 4,40, 100, 2, and 5 mg L^-1, respectively. By using the Adi medium and the scraping technique, the regeneration frequencies of the mature embryos of CB037, Lunxuan 987, Hart 6172, Yangmai 6, Bobwhite, Zheng 9023, Shi 4 185, and Jimai 20 became 85.6, 60,1, 46.0, 42.1,42.0, 34.0, 33.0, and 32.0%, respectively, which were about 5-8 times higher than that obtained from the conventional culture mediums and techniques. This novel regeneration system could be helpful in wheat transformation.
基金supported by National Natural Science Foundation of China(Grant No. 51175287)National Science and Technology Major Project(Grant No. 2011ZX02403)
文摘Content-based 3D model retrieval is of great help to facilitate the reuse of existing designs and to inspire designers during conceptual design. However, there is still a gap to apply it in industry due to the low time efficiency. This paper presents two new methods with high efficiency to build a Content-based 3D model retrieval system. First, an improvement is made on the "Shape Distribution (D2)" algorithm, and a new algorithm named "Quick D2" is proposed. Four sample 3D mechanical models are used in an experiment to compare the time cost of the two algorithms. The result indicates that the time cost of Quick D2 is much lower than that of D2, while the descriptors extracted by the two algorithms are almost the same. Second, an expandable 3D model repository index method with high performance, namely, RBK index, is presented. On the basis of RBK index, the search space is pruned effectively during the search process, leading to a speed up of the whole system. The factors that influence the values of the key parameters of RBK index are discussed and an experimental method to find the optimal values of the key parameters is given. Finally, "3D Searcher", a content-based 3D model retrieval system is developed. By using the methods proposed, the time cost for the system to respond one query online is reduced by 75% on average. The system has been implemented in a manufacturing enterprise, and practical query examples during a case of the automobile rear axle design are also shown. The research method presented shows a new research perspective and can effectively improve the content-based 3D model retrieval efficiency.
基金supported by the National Natural Science Foundation of China(Nos.12122206 and 12272129)the Natural Science Foundation of Hunan Province of China(No.2024JJ4004)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24A020006)。
文摘An easily stackable multi-layer quasi-zero-stiffness(ML-QZS)meta-structure is proposed to achieve highly efficient vibration isolation performance at low frequency.First,the distributed shape optimization method is used to design the unit cel,i.e.,the single-layer QZS(SL-QZS)meta-structure.Second,the stiffness feature of the unit cell is investigated and verified through static experiments.Third,the unit cells are stacked one by one along the direction of vibration isolation,and thus the ML-QZS meta-structure is constructed.Fourth,the dynamic modeling of the ML-QZS vibration isolation metastructure is conducted,and the dynamic responses are obtained from the equations of motion,and verified by finite element(FE)simulations.Finally,a prototype of the ML-QZS vibration isolation meta-structure is fabricated by additive manufacturing,and the vibration isolation performance is evaluated experimentally.The results show that the vibration isolation performance substantially enhances when the number of unit cells increases.More importantly,the ML-QZS meta-structure can be easily extended in the direction of vibration isolation when the unit cells are properly stacked.Hence,the ML-FQZS vibration isolation meta-structure should be a fascinating solution for highly efficient vibration isolation performance at low frequency.
基金support provided by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(HZQB-KCZYB-2020030)the Research Grants Council of Hong Kong(Project No:AoE/M-402/20.)+1 种基金the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050248)the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.
文摘Experimental methods,including mercury pressure,nuclear magnetic resonance(NMR)and core(wateroil)displacement,are used to examine the effects of high-multiple water injection(i.e.water injection with high injected pore volume)on rock properties,pore structure and oil displacement efficiency of an oilfield in the western South China Sea.The results show an increase in the permeability of rocks along with particle migration,an increase in the pore volume and the average pore throat radius,and enhanced heterogeneity after high-multiple water injection.Compared with normal water injection methods,a high-multiple water injection is more effective in improving the oil displacement efficiency.The degree of recovery increases faster in the early stage due to the expansion of the swept area,and the transition from oil-wet to water-wet.The degree of recovery increases less in the late stage due to various factors,including the enhancement of heterogeneity in the rocks.Considering both the economic aspect and the production limit of water flooding,it is recommended to adopt other technologies to further enhance oil recovery after 300 PV water injection.
文摘The deferred correction(DeC)is an iterative procedure,characterized by increasing the accuracy at each iteration,which can be used to design numerical methods for systems of ODEs.The main advantage of such framework is the automatic way of getting arbitrarily high order methods,which can be put in the Runge-Kutta(RK)form.The drawback is the larger computational cost with respect to the most used RK methods.To reduce such cost,in an explicit setting,we propose an efcient modifcation:we introduce interpolation processes between the DeC iterations,decreasing the computational cost associated to the low order ones.We provide the Butcher tableaux of the new modifed methods and we study their stability,showing that in some cases the computational advantage does not afect the stability.The fexibility of the novel modifcation allows nontrivial applications to PDEs and construction of adaptive methods.The good performances of the introduced methods are broadly tested on several benchmarks both in ODE and PDE contexts.
基金sponsored by the National Key Basic Research Program of China(2007CB2095)
文摘Based on reserve abundance,large gas fields in China can be divided into two types:type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,dominated by stratigraphic and lithologic gas reservoirs.The formation of these two types of large gas fields is related to the highly efficient accumulation of natural gas.The accumulation of high abundance gas fields is dependent on the rapid maturation of the source kitchen and huge residual pressure difference between the gas source kitchen and reservoir,which is the strong driving force for natural gas migration to traps.Whereas the accumulation of low abundance gas fields is more complicated,involving both volume flow charge during the burial stage and diffusion flow charge during the uplift stage,which results in large area accumulation and preservation of natural gas in low porosity and low permeability reservoirs.This conclusion should assist gas exploration in different geological settings.
基金supported by the National Key Research and Development Program of China (Grant No.2018YFB1500103)the National Natural Science Foundation of China (Grant No.61674084)+4 种基金the Overseas Expertise Introduction Project for Discipline Innovation of Higher Education of China (Grant No.B16027)the Tianjin Science and Technology Project (Grant No.18ZXJMTG00220)the Fundamental Research Funds for the Central Universities of Nankai University (Grant Nos.63191736,ZB19500204)the Natural Science Foundation of Tianjin (Grant No.20JCQNJC02070)the China Postdoctoral Science Foundation (Grant No.2020T130317)。
文摘Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage(VOC) and power conversion efficiency(PCE). Lithium chloride(Li Cl) was added into the tin oxide(SnO_(2)) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer(ETL)/perovskite interface.Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and V_(OC) of 1.92 V, which is the highest PCE and VOCin N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.
文摘A cyclometalated greenish-yellow emitter 2,3-diphenylimidazo[1,2-a]pyridine iridium(Ill) complex is successfully synthesized and used to fabricate phosphorescent organic light-emitting diodes. The optimized device exhibits a greenish-yellow emission with the peak at 523nm and a strong shoulder at 557nm, corresponding to Commission Internationale de l'Eclairage coordinates of (0.38, 0.68). The full width at half maximum of the device is 93 nm, which is broader than the fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] based reference device of 78 nm. Meanwhile, a maximum current efficiency of 62.6 cd/A (47.51m/W) is obtained. This result is higher than a maximum current efficiency of 54.8 cd/A (431m/W) of the Ir(ppy)a based device. The results indicate that this new iridium complex may have potential applications in fabricating high color rendering index white organic light emitting diodes.
基金Project(2015-GX-108A)supported by Qinghai Provincial Science and Technology Support Program,China
文摘The bottleneck of strontium compounds preparing from celestite is the promotion of Sr/S isolation efficiency.Low energy consumption and zero release method for isolating Sr/S in preparing Sr(OH)2 process from celestite in mild condition was described.Sr element remained in precipitation with formation of Sr(OH)2,while S element entered into leachate with formation of Na2SO4.The effects of initial concentration of NaOH,conversion temperature,liquid-to-solid(L/S)ratio and conversion time on Sr/S ratio of samples for celestite conversion were systematically investigated by experiments.The results demonstrated that the efficiency of Sr/S isolation increased with the initial concentration of NaOH,L/S ratio and conversion time,and decreased with conversion temperature.The maximum conversion ratio of Sr(OH)2 was 93.88%under the optimum condition,whose Sr/S ratio of sample could reach to 41.16.It illustrated that better isolation efficiency of celestite could be achieved in alkaline treatment.The results of SEM-EDS analyses demonstrated that the conversion reaction was a dissolution-precipitation process.
基金supported by the Beijing Scholars Program[BSP041]。
文摘Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus(SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif(PAM) that the canonical Streptococcus pyogenes Cas9(SpCas9) or its variants(e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor(SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.
基金supported by the Science Fund for Creative Research Groups(21421004)the National Basic Research 973 Program(2013CB733700)NSFC/China(21172073,21372082,21572062 and 91233207)
文摘A distinctive method is proposed by simply utilizing ultrasonic technique in Ti02 electrode fabrication in order to improve the optoelectronic performance of dye-sensitized solar cells (DSSCs). Dye molecules are at random and single molecular state in the ultrasonic field and the ultrasonic wave favors the diffusion and adsorption processes of dye molecules. As a result, the introduction of ultrasonic technique at room temperature leads to faster and more well-distributed dye adsorption on TiO2 as well as higher cell efficiency than regular deposition, thus the fabrication time is markedly reduced. It is found that the device based on 40 kHz ultrasonic (within 1 h) with N719 exhibits a Voc of 789 mV, Jsc of 14.94 mA]cm2 and fill factor (FF) of 69.3, yielding power conversion efficiency (PCE) of 8.16%, which is higher than device regularly dyed for 12 h (PCE = 8.06%). In addition, the DSSC devices obtain the best efficiency (PCE = 8.68%) when the ultrasonic deposition time increases to 2.5 h. The DSSCs fabricated via ultrasonic technique presents more dye loading, larger photocurrent, less charge recombination and higher photovoltage. The charge extraction and electron impedance spectroscopy (EIS) were performed to understand the influence of ultrasonic technique on the electron recombination and performance of DSSCs.
文摘A highly efficient and convenient procedure for the enantioselective synthesis of (S)-Rivastigmine, a cholinergic agent for the treatment of mild to moderate dementia of the Alzheimer’s type and dementia due to Parkinson’s disease, is accomplished by the treatment of versatile, readily accessible (S)-(-)-2-methyl-2-propanesulfinamide with 3-hydroxyacetophenone. This protocol provides high yield and excellent enantiomeric excess in short step synthesis.
基金financially supported by the National Basic Research Program of China, Fundamental Studies of Perovskite Solar Cells (Grant 2015CB932200)the Natural Science Foundation of China (Grants 51602149 and 61705102)+4 种基金Natural Science Foundation of Jiangsu Province, China(Grants BK20161011 and BK20161010)Young 1000 Talents Global Recruitment Program of ChinaJiangsu Specially-Appointed Professor program"Six talent peaks" Project in Jiangsu Province, ChinaStartup from Nanjing Tech University
文摘Interfacial layer has a significant impact on the achievement of highly efficient organic–inorganic hybrid perovskite solar cells(PSCs). Here, we introduced a nano-ZnMgO(magnesium doped ZnO, abbreviated as ZnMgO) as interfacial layer between [6, 6]-Phenyl C_(61) butyric acid methyl ester(PC_(61) BM) layer and Al electrode to replace LiF or ZnO interlayer and enhance device performance. The device efficiency has been improved from 11.43% to 15.61% and the hysteresis was decreased dramatically. Such huge enhancement of power convert efficiency(PCE) can be attributed to the low dark current density, enhancement of electron-selective contact, and low energy barrier at the PC_(61) BM/Al interface. We suggest that this simple nano-scale interlayer can provide an efficient charge transport and extraction for highly efficient PSCs.
基金Natural Science Research(Department of Education)Project of Higher Education Institutions in Guangdong Province(Grant No.2018KQNCX063)Applied Basic Research Fund of Guangdong Province(Grant No.2024B1515020071)+1 种基金National Natural Science Foundation of China(Grant Nos.52371217 and 52150410411)Guangdong Provincial Science and Technology Plan Project(Grant No.2023A0505020009)。
文摘Li-rich Mn-based oxides(LRMOs)hold great promise as next-generation cathode materials for high-energy Li-ion batteries because of their low cost and high capacity.Nevertheless,the practical application of LRMOs is impeded by their low initial Coulombic efficiency and rapid voltage decay.Herein,a V-doped layered-spinel coherent layer is constructed on the surface of a Co-free LRMO through a simple treatment with NH_(4)VO_(3).The layered-spinel coherent layer with 3D ion channels enhanced Li+diffusion efficiency,mitigates surface-inter-face reactions and suppresses irreversible oxygen release.Notably,V-doping significantly reduces the Bader charge of oxygen atoms,thereby impeding excessive oxidation of oxygen ions and further enhancing the stability of O-redox.The modified LRMO exhibites a remarkable initial Coulombic efficiency of 91.6%,signifi-cantly surpassing that of the original LRMO(74.4%).Furthermore,the treated sample showes an impressive capacity retention rate of 91.9%after 200 cycles,accompanied by a voltage decay of merely 0.47 mV per cycle.The proposed treatment approach is straightforward and significantly improves the initial Coulombic efficiency,voltage stability,and capacity stability of LRMO cathode materials,thus holding considerable promise for the development of high-energy Li-ion batteries.
文摘Based on the current problems in carrot production,Laixi City of Shandong Province adopted 5 m large arch shed double-layer plastic film to cultivate " Three Red" carrot,selected varieties suitable for export,ridging double-row mechanical drilling,integrated water and fertilizer management,carrot residue composting and returning to field,and finally realized safe and high efficient production of facility carrot industrialization.
基金The National Basic Research Program( 973 Plan) of China(2012CB724201)
文摘On the basis of reviewing the progress in the high efficient enrichment from secondary resources of low grade precious metals at home and abroad, a process route of the high efficient enrichment precious metals from secondary resources of low-grade metals by adding iron oxide as the trapping agent, reducing agent, additive, mixing uniformly and grinding, pelletizing, reduction, grinding and separation, and selectively acid leaching iron has been put forward in this paper. The experiments of reduction, grinding and separation, and selectively acid leaching iron were carried out mainly. Under the decided experiment parameters and conditions, iron generated during the reduction can trap precious metals during reduction, high active alloy powders were obtained from the reduced products by grinding and separation, the concentration of precious metals was obtained by acid leaching high active alloy powders. The better enrichment effect was obtained by adopting the technical route of processing. Other low grade noble metal materials and enrichment ratio of precious metals from the materials to acid products was high through acid leaching. This process has the advantages of simple process, environmental-friendly, strong adaptability of raw materials, high concentration ratio, which was regarded as a kind of the general efficient enrichment technology of low grade precious metal materials.