Recent studies have shown that deep learning(DL)models can skillfully forecast El Niño–Southern Oscillation(ENSO)events more than 1.5 years in advance.However,concerns regarding the reliability of predictions ma...Recent studies have shown that deep learning(DL)models can skillfully forecast El Niño–Southern Oscillation(ENSO)events more than 1.5 years in advance.However,concerns regarding the reliability of predictions made by DL methods persist,including potential overfitting issues and lack of interpretability.Here,we propose ResoNet,a DL model that combines CNN(convolutional neural network)and transformer architectures.This hybrid architecture enables our model to adequately capture local sea surface temperature anomalies as well as long-range inter-basin interactions across oceans.We show that ResoNet can robustly predict ENSO at lead times of 19 months,thus outperforming existing approaches in terms of the forecast horizon.According to an explainability method applied to ResoNet predictions of El Niño and La Niña from 1-to 18-month leads,we find that it predicts the Niño-3.4 index based on multiple physically reasonable mechanisms,such as the recharge oscillator concept,seasonal footprint mechanism,and Indian Ocean capacitor effect.Moreover,we demonstrate for the first time that the asymmetry between El Niño and La Niña development can be captured by ResoNet.Our results could help to alleviate skepticism about applying DL models for ENSO prediction and encourage more attempts to discover and predict climate phenomena using AI methods.展开更多
Amyotrophic lateral sclerosis(ALS) is a devastating motoneuron disease,in which lower motoneurons lose control of skeletal muscles.Degeneration of neuromuscular junctions(NMJs) occurs at the initial stage of ALS.Dipep...Amyotrophic lateral sclerosis(ALS) is a devastating motoneuron disease,in which lower motoneurons lose control of skeletal muscles.Degeneration of neuromuscular junctions(NMJs) occurs at the initial stage of ALS.Dipeptide repeat proteins(DPRs) from G4C2repeat-associated non-ATG(RAN) translation are known to cause C9orf72-associated ALS(C9-ALS).However,DPR inclusion burdens are weakly correlated with neurodegenerative areas in C9-ALS patients,indicating that DPRs may exert cell non-autonomous effects,in addition to the known intracellular pathological mechanisms.Here,we report that poly-GA,the most abundant form of DPR in C9-ALS,is released from cells.Local administration of poly-GA proteins in peripheral synaptic regions causes muscle weakness and impaired neuromuscular transmission in vivo.The NMJ structure cannot be maintained,as evidenced by the fragmentation of postsynaptic acetylcholine receptor(AChR) clusters and distortion of presynaptic nerve terminals.Mechanistic study demonstrated that extracellular poly-GA sequesters soluble Agrin ligands and inhibits Agrin-MuSK signaling.Our findings provide a novel cell non-autonomous mechanism by which poly-GA impairs NMJs in C9-ALS.Thus,targeting NMJs could be an early therapeutic intervention for C9-ALS.展开更多
Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properti...Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properties. Apart from van-der-Waals heterostructures,herein, we report a novel nanocomposite with the structure of Pt–Ru bimetallic nanoparticles covalently-bonded onto multi-walled carbon nanotubes (MWCNTs)(Pt–Ru@MWCNT), which have been successfully fabricated via a facile and green synthesis method. It is demonstrated that the Pt–Ru@MWCNT nanocomposite possesses much enhanced electrocatalytic activity with the electrochemical active surface area(ECSA) of 110.4 m^(2)·g^(-1)for Pt towards MOR, which is 2.67 and 4.0 times higher than those of 20wt%commercial Pt@C and Pt-based nanocomposite prepared by other method, due to the improved electron-transfer properties originated from M–O–C covalent bonds. This work provides us a new strategy for the structural design of highly-efficient electrocatalysts in boosting MOR performance.展开更多
AIM: To evaluate the reliability and accuracy of threedimensional(3D) reconstruction for liver resection in patients with hepatic alveolar echinococcosis(HAE).METHODS: One-hundred and six consecutive patients with HAE...AIM: To evaluate the reliability and accuracy of threedimensional(3D) reconstruction for liver resection in patients with hepatic alveolar echinococcosis(HAE).METHODS: One-hundred and six consecutive patients with HAE underwent hepatectomy at our hospital between May 2011 and January 2015. Fifty-nine patients underwent preoperative 3D reconstruction and "virtual" 3D liver resection before surgery(Group A). Another 47 patients used conventional imaging methods for preoperative assessment(Group B). Outcomes of hepatectomy were compared between the two groups.RESULTS: There was no significant difference in preoperative data between the two groups. Compared with patients in Group B, those in Group A had a significantly shorter operation time(227.1 ± 51.4 vs 304.6 ± 88.1 min; P < 0.05), less intraoperative blood loss(308.1 ± 135.4 vs 458.1 ± 175.4 m L; P < 0.05), and lower requirement for intraoperative blood transfusion(186.4 ± 169.6 vs 289.4 ± 199.2 m L; P < 0.05). Estimated resection liver volumes in bothgroups had good correlation with actual graft weight(Group A: r = 0.978; Group B: r = 0.960). There was a significant higher serum level of albumin in Group A(26.3 ± 5.9 vs 22.6 ± 4.3 g/L, P < 0.05). Other postoperative laboratory parameters(serum levels of aminotransferase and bilirubin; prothrombin time) and duration of postoperative hospital stay were similar. Sixteen complications occurred in Group A and 19 in Group B. All patients were followed for 3-46(mean, 17.3) mo. There was no recurrence of lesions in Group A, but two recurrences in Group B. There were three deaths: two from cerebrovascular accident, and one from car accident.CONCLUSION: 3D reconstruction provides comprehensive and precise anatomical information for the liver. It also improves the chance of success and reduces the risk of hepatectomy in HAE.展开更多
The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combi...The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.展开更多
Hepatocellular carcinoma(HCC)is one of the deadliest cancers due to its complexities,reoccurrence after surgical resection,metastasis and heterogeneity.In addition to sorafenib and lenvatinib for the treatment of HCC ...Hepatocellular carcinoma(HCC)is one of the deadliest cancers due to its complexities,reoccurrence after surgical resection,metastasis and heterogeneity.In addition to sorafenib and lenvatinib for the treatment of HCC approved by FDA,various strategies including transarterial chemoembolization,radiotherapy,locoregional therapy and chemotherapy have been investigated in clinics.Recently,cancer nanotechnology has got great attention for the treatment of various cancers including HCC.Both passive and active targetings are progressing at a steady rate.Herein,we describe the lessons learned from pathogenesis of HCC and the understanding of targeted and non-targeted nanoparticles used for the delivery of small molecules,monoclonal antibodies,miRNAs and peptides.Exploring current efficacy is to enhance tumor cell response of chemotherapy.It highlights the opportunities and challenges faced by nanotechnologies in contemporary hepatocellular carcinoma therapy,where personalized medicine is increasingly becoming the mainstay.Overall objective of this review is to enhance our understanding in the design and development of nanotechnology for treatment of HCC.展开更多
This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz...This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.展开更多
This study examines spatial and temporal changes in 16 extreme temperature indices at 37 weather stations in Xinjiang and their associations with changes in climate means during 1961-2008. Linear regression analyses r...This study examines spatial and temporal changes in 16 extreme temperature indices at 37 weather stations in Xinjiang and their associations with changes in climate means during 1961-2008. Linear regression analyses reveal that significant increas- ing trends in temperature were observed over Xinjiang, with the rate of 0.13 ~C/decade, 0.24 ~C/decade, and 0.52 ~C/decade for annual mean temperature, annual maximum, and minimum temperature, respectively. Annual fi＇equency of cool nights （days） has decreased by -2.45 days/decade （-0.86 days/decade）, whereas the frequency of warm nights （days） has increased by 4.85 days/decade （1.62 days/decade）. Seasonally, the frequencies of summer warm nights and days are changing more rap- idly than the corresponding frequencies for cool nights and days. However, normalization of the extreme and mean series shows that the rate of changes in extreme temperature events are generally less than those of mean temperatures, except for winter cold nights which are changing as rapidly as the winter mean minimum temperatures. These results indicate that there have been seasonally and diurnally asymmetric changes in extreme temperature events relative to recent increases in tempera- ture means in Xinjiang.展开更多
A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative...A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative gravity points.Processing of the absolute data,pre-processing of the relative data and gravity network adjustment model are briefly described.Based a constrained weighted least squares,the combined adjustment of absolute and relative gravity measurements results in the gravity values with a precision of about±4.1μGal.展开更多
The heat exchanger network(HEN)in a syngas-to-methanol process was designed and optimized based on pinch technology under stable operating conditions to balance the energy consumption and economic gain.In actual indus...The heat exchanger network(HEN)in a syngas-to-methanol process was designed and optimized based on pinch technology under stable operating conditions to balance the energy consumption and economic gain.In actual industrial processes,fluctuations in production inevitably affect the stable operation of HENs.A flexibility analysis of the HEN was carried out to minimize such disturbances using the downstream paths method.The results show that two-third of the downstream paths cannot meet flexibility requirements,indicating that the HEN does not have enough flexibility to accommodate the disturbances in actual production.A flexible HEN was then designed with the method of dividing and subsequent merging of streams,which led to 13.89%and 20.82%reductions in energy consumption and total cost,respectively.Owing to the sufficient area margin and additional alternative heat exchangers,the flexible HEN was able to resist interference and maintain production stability and safety,with the total cost increasing by just 4.08%.展开更多
CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of Ce...CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.展开更多
The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulatio...The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulation.At present,such characteristic parameters are mainly obtained by empirical methods,which typically result in relatively large errors.By analyzing experimentally polymer adsorption,permeability decline,inaccessible pore volume,viscosity-concentration relationship,and rheology,in this study,a conversion equation is provided to convert the experimental data into the parameters needed for the numerical simulation.Some examples are provided to demonstrate the reliability of the proposed approach.展开更多
A male-specific SCAR DNA marker was developed using a RAPD DNA marker specific for male plants of Salacca zalacca var. zalacca （salak palm）. The marker is 1579 bp long and has a GC content of 38.5 %. Its sequence co...A male-specific SCAR DNA marker was developed using a RAPD DNA marker specific for male plants of Salacca zalacca var. zalacca （salak palm）. The marker is 1579 bp long and has a GC content of 38.5 %. Its sequence contains 1 or 2 open reading frames, indicating the marker is probably a coding region. No highly similar sequences were found in a search of the GenBank database. Sexes were identified using the SCAR DNA marker for three kinds of seedlings grouped by the number of seeds per fruit （1, 2 or 3）. The sex ratio of female to male did not differ significantly from 1：1 for the three kinds of seedlings, implying that the number of seeds per fruit is not a reliable index to identify the sex of a seedling.展开更多
Automated chromosome classification has been an important pattern recognition problem for decades. In order to im-prove the performance of automated chromosome classification, artificial intelligence and machine learn...Automated chromosome classification has been an important pattern recognition problem for decades. In order to im-prove the performance of automated chromosome classification, artificial intelligence and machine learning methods have been widely used in the computer-assisted chromosome detection and classification systems. This paper is focused on these algorithms, especially on artificial neural network (ANN) and wavelet transform algorithms. The principle and the realization of these algorithms are analyzed. Results of these algorithms are compared and discussed.展开更多
Chromosome segmentation is the most important step in the automatic chromosome analysis system. Since in almost every metaphase image partial touching and overlapping of chromosomes are a common phenomenon, how to sep...Chromosome segmentation is the most important step in the automatic chromosome analysis system. Since in almost every metaphase image partial touching and overlapping of chromosomes are a common phenomenon, how to separate these chromosomes correctly is a difficult yet vital problem. A number of attempts have been made to deal with this problem. This paper is focused on these attempts. Some algorithms are investigated. The principle and the realization of these algorithms are analyzed. Results of these algorithms are compared and discussed.展开更多
基金supported by the Shanghai Artificial Intelligence Laboratory and National Natural Science Foundation of China(Grant No.42088101 and 42030605).
文摘Recent studies have shown that deep learning(DL)models can skillfully forecast El Niño–Southern Oscillation(ENSO)events more than 1.5 years in advance.However,concerns regarding the reliability of predictions made by DL methods persist,including potential overfitting issues and lack of interpretability.Here,we propose ResoNet,a DL model that combines CNN(convolutional neural network)and transformer architectures.This hybrid architecture enables our model to adequately capture local sea surface temperature anomalies as well as long-range inter-basin interactions across oceans.We show that ResoNet can robustly predict ENSO at lead times of 19 months,thus outperforming existing approaches in terms of the forecast horizon.According to an explainability method applied to ResoNet predictions of El Niño and La Niña from 1-to 18-month leads,we find that it predicts the Niño-3.4 index based on multiple physically reasonable mechanisms,such as the recharge oscillator concept,seasonal footprint mechanism,and Indian Ocean capacitor effect.Moreover,we demonstrate for the first time that the asymmetry between El Niño and La Niña development can be captured by ResoNet.Our results could help to alleviate skepticism about applying DL models for ENSO prediction and encourage more attempts to discover and predict climate phenomena using AI methods.
基金supported by the National Key Research and Development Program of China (2022YFF1000500 to K.Z. and2021YFA1101100 to C.S.)Zhejiang Provincial Natural Science Foundation(LZ22C110002 to C.S.)National Natural Science Foundation of China(32271031 to K.Z. and 82230038, 31871203, and 32071032 to C.S.)。
文摘Amyotrophic lateral sclerosis(ALS) is a devastating motoneuron disease,in which lower motoneurons lose control of skeletal muscles.Degeneration of neuromuscular junctions(NMJs) occurs at the initial stage of ALS.Dipeptide repeat proteins(DPRs) from G4C2repeat-associated non-ATG(RAN) translation are known to cause C9orf72-associated ALS(C9-ALS).However,DPR inclusion burdens are weakly correlated with neurodegenerative areas in C9-ALS patients,indicating that DPRs may exert cell non-autonomous effects,in addition to the known intracellular pathological mechanisms.Here,we report that poly-GA,the most abundant form of DPR in C9-ALS,is released from cells.Local administration of poly-GA proteins in peripheral synaptic regions causes muscle weakness and impaired neuromuscular transmission in vivo.The NMJ structure cannot be maintained,as evidenced by the fragmentation of postsynaptic acetylcholine receptor(AChR) clusters and distortion of presynaptic nerve terminals.Mechanistic study demonstrated that extracellular poly-GA sequesters soluble Agrin ligands and inhibits Agrin-MuSK signaling.Our findings provide a novel cell non-autonomous mechanism by which poly-GA impairs NMJs in C9-ALS.Thus,targeting NMJs could be an early therapeutic intervention for C9-ALS.
基金supported by the National Key Research and Development Program of China[grant number 2020YFA0608000]the National Natural Science Foundation of China[grant number 42030605].
基金the support from Shanghai QingZhen Test Technology Co.,Ltd.,China (No.880772)Dalian Jin Dian Biotechnology Co.,Ltd.,China (No.880988)+5 种基金Anhui Chromatographic Instrument Co.,Ltd.,China (No.880511)the Key Project of Anhui Provincial Department of Education,China (No.2023AH051634)the Innovative Research Team of Undergraduates,China (Nos.S202110879087 and S202210879085)the Research Funds of Anhui Science and Technology University,China (No.FZ220179)the Foundation of Anhui Science and Technology University,China (No.HCWD202001)the Science and Technology Planning Project of Bengbu City,China (No.2022gx10)。
文摘Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properties. Apart from van-der-Waals heterostructures,herein, we report a novel nanocomposite with the structure of Pt–Ru bimetallic nanoparticles covalently-bonded onto multi-walled carbon nanotubes (MWCNTs)(Pt–Ru@MWCNT), which have been successfully fabricated via a facile and green synthesis method. It is demonstrated that the Pt–Ru@MWCNT nanocomposite possesses much enhanced electrocatalytic activity with the electrochemical active surface area(ECSA) of 110.4 m^(2)·g^(-1)for Pt towards MOR, which is 2.67 and 4.0 times higher than those of 20wt%commercial Pt@C and Pt-based nanocomposite prepared by other method, due to the improved electron-transfer properties originated from M–O–C covalent bonds. This work provides us a new strategy for the structural design of highly-efficient electrocatalysts in boosting MOR performance.
基金Supported by National Natural Science Foundation of China,No.81160201 and No.U1303222
文摘AIM: To evaluate the reliability and accuracy of threedimensional(3D) reconstruction for liver resection in patients with hepatic alveolar echinococcosis(HAE).METHODS: One-hundred and six consecutive patients with HAE underwent hepatectomy at our hospital between May 2011 and January 2015. Fifty-nine patients underwent preoperative 3D reconstruction and "virtual" 3D liver resection before surgery(Group A). Another 47 patients used conventional imaging methods for preoperative assessment(Group B). Outcomes of hepatectomy were compared between the two groups.RESULTS: There was no significant difference in preoperative data between the two groups. Compared with patients in Group B, those in Group A had a significantly shorter operation time(227.1 ± 51.4 vs 304.6 ± 88.1 min; P < 0.05), less intraoperative blood loss(308.1 ± 135.4 vs 458.1 ± 175.4 m L; P < 0.05), and lower requirement for intraoperative blood transfusion(186.4 ± 169.6 vs 289.4 ± 199.2 m L; P < 0.05). Estimated resection liver volumes in bothgroups had good correlation with actual graft weight(Group A: r = 0.978; Group B: r = 0.960). There was a significant higher serum level of albumin in Group A(26.3 ± 5.9 vs 22.6 ± 4.3 g/L, P < 0.05). Other postoperative laboratory parameters(serum levels of aminotransferase and bilirubin; prothrombin time) and duration of postoperative hospital stay were similar. Sixteen complications occurred in Group A and 19 in Group B. All patients were followed for 3-46(mean, 17.3) mo. There was no recurrence of lesions in Group A, but two recurrences in Group B. There were three deaths: two from cerebrovascular accident, and one from car accident.CONCLUSION: 3D reconstruction provides comprehensive and precise anatomical information for the liver. It also improves the chance of success and reduces the risk of hepatectomy in HAE.
基金Supported by the Fundamental Research Funds for the Central Universities(2017XKQY066)
文摘The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.
基金supported by the National Natural Science Foun-dation of China(Grants 81571799,81773193,81771929 and 81773642)
文摘Hepatocellular carcinoma(HCC)is one of the deadliest cancers due to its complexities,reoccurrence after surgical resection,metastasis and heterogeneity.In addition to sorafenib and lenvatinib for the treatment of HCC approved by FDA,various strategies including transarterial chemoembolization,radiotherapy,locoregional therapy and chemotherapy have been investigated in clinics.Recently,cancer nanotechnology has got great attention for the treatment of various cancers including HCC.Both passive and active targetings are progressing at a steady rate.Herein,we describe the lessons learned from pathogenesis of HCC and the understanding of targeted and non-targeted nanoparticles used for the delivery of small molecules,monoclonal antibodies,miRNAs and peptides.Exploring current efficacy is to enhance tumor cell response of chemotherapy.It highlights the opportunities and challenges faced by nanotechnologies in contemporary hepatocellular carcinoma therapy,where personalized medicine is increasingly becoming the mainstay.Overall objective of this review is to enhance our understanding in the design and development of nanotechnology for treatment of HCC.
基金The authors gratefully acknowledge the financial support provided by the 12th Five-Year Plan of National Science and Technology Support (Grant 2012BAA04B02)the National Natural Science Foundation of China (No.21406261).
文摘This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.
基金funded by a special scientific research project (GYHY200706008) in the public welfare industry (meteorology)the "Western Light" Project (RCPY200902) of the Chinese Academy of Sciencesthe National Natural Science Foundation(41171066) of Xinjiang Institute of Ecology and Geography
文摘This study examines spatial and temporal changes in 16 extreme temperature indices at 37 weather stations in Xinjiang and their associations with changes in climate means during 1961-2008. Linear regression analyses reveal that significant increas- ing trends in temperature were observed over Xinjiang, with the rate of 0.13 ~C/decade, 0.24 ~C/decade, and 0.52 ~C/decade for annual mean temperature, annual maximum, and minimum temperature, respectively. Annual fi＇equency of cool nights （days） has decreased by -2.45 days/decade （-0.86 days/decade）, whereas the frequency of warm nights （days） has increased by 4.85 days/decade （1.62 days/decade）. Seasonally, the frequencies of summer warm nights and days are changing more rap- idly than the corresponding frequencies for cool nights and days. However, normalization of the extreme and mean series shows that the rate of changes in extreme temperature events are generally less than those of mean temperatures, except for winter cold nights which are changing as rapidly as the winter mean minimum temperatures. These results indicate that there have been seasonally and diurnally asymmetric changes in extreme temperature events relative to recent increases in tempera- ture means in Xinjiang.
文摘A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative gravity points.Processing of the absolute data,pre-processing of the relative data and gravity network adjustment model are briefly described.Based a constrained weighted least squares,the combined adjustment of absolute and relative gravity measurements results in the gravity values with a precision of about±4.1μGal.
基金This work is financially supported by"the Fundamental Research Funds for the Central Universities"(2020XJHH01)the Yueqi Distinguished Scholar Project of China University of Mining and Technology(Beijing)(2020JCB02).
文摘The heat exchanger network(HEN)in a syngas-to-methanol process was designed and optimized based on pinch technology under stable operating conditions to balance the energy consumption and economic gain.In actual industrial processes,fluctuations in production inevitably affect the stable operation of HENs.A flexibility analysis of the HEN was carried out to minimize such disturbances using the downstream paths method.The results show that two-third of the downstream paths cannot meet flexibility requirements,indicating that the HEN does not have enough flexibility to accommodate the disturbances in actual production.A flexible HEN was then designed with the method of dividing and subsequent merging of streams,which led to 13.89%and 20.82%reductions in energy consumption and total cost,respectively.Owing to the sufficient area margin and additional alternative heat exchangers,the flexible HEN was able to resist interference and maintain production stability and safety,with the total cost increasing by just 4.08%.
基金Supported by the National Natural Science Foundation of China(51204179,51204182,51674256)The Natural Science Foundation of Jiangsu Province,China(BK20141242)
文摘CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.
基金supported by Hubei Provincial Natural Science Foundation of China(Grant No.2020CFB377)the National Natural Science Foundation of China(Grant No.52104020).
文摘The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulation.At present,such characteristic parameters are mainly obtained by empirical methods,which typically result in relatively large errors.By analyzing experimentally polymer adsorption,permeability decline,inaccessible pore volume,viscosity-concentration relationship,and rheology,in this study,a conversion equation is provided to convert the experimental data into the parameters needed for the numerical simulation.Some examples are provided to demonstrate the reliability of the proposed approach.
基金supported by the State Administration of Forestry of China(Grant Numbers 201204307-03,2007-4-11,and 2012-LY-052)the Research Institute of Tropical Forestry,Chinese Academy of Forestry(Grant Number RITFKYYW2010-02)
文摘A male-specific SCAR DNA marker was developed using a RAPD DNA marker specific for male plants of Salacca zalacca var. zalacca （salak palm）. The marker is 1579 bp long and has a GC content of 38.5 %. Its sequence contains 1 or 2 open reading frames, indicating the marker is probably a coding region. No highly similar sequences were found in a search of the GenBank database. Sexes were identified using the SCAR DNA marker for three kinds of seedlings grouped by the number of seeds per fruit （1, 2 or 3）. The sex ratio of female to male did not differ significantly from 1：1 for the three kinds of seedlings, implying that the number of seeds per fruit is not a reliable index to identify the sex of a seedling.
文摘Automated chromosome classification has been an important pattern recognition problem for decades. In order to im-prove the performance of automated chromosome classification, artificial intelligence and machine learning methods have been widely used in the computer-assisted chromosome detection and classification systems. This paper is focused on these algorithms, especially on artificial neural network (ANN) and wavelet transform algorithms. The principle and the realization of these algorithms are analyzed. Results of these algorithms are compared and discussed.
文摘Chromosome segmentation is the most important step in the automatic chromosome analysis system. Since in almost every metaphase image partial touching and overlapping of chromosomes are a common phenomenon, how to separate these chromosomes correctly is a difficult yet vital problem. A number of attempts have been made to deal with this problem. This paper is focused on these attempts. Some algorithms are investigated. The principle and the realization of these algorithms are analyzed. Results of these algorithms are compared and discussed.
