High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for ...High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for studying delicate phase transitions caused by complex interactions in Mott insulators.With time-resolved transient reflectivity measurements,we identified the new phases in the spin–orbit Mott insulator Sr_(3)Ir_(2)O_7 at 300 K that was previously unidentified using conventional approaches such as x-ray diffraction.Significant pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity?R/R reveal the changes of electronic structure caused by lattice distortions,and reflect the critical phenomena of phase transitions.Our findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators.展开更多
Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical he...Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.展开更多
The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalys...The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalysts was proposed.The process included alkali (NaOH) hydrothermal treatment,sulfuric acid washing,and calcination.Anatase TiO_(2) in spent SCR catalyst was reconstructed by forming Na_(2)Ti_(2)O_(4)(OH)_(2) nanosheet during NaOH hydrothermal treatment and H_(2)Ti_(2)O_(4)(OH)_(2) during sulfuric acid washing.Anatase TiO_(2) was recovered by decomposing H_(2)Ti_(2)O_(4)(OH)_(2) during calcination.The surface pore properties of the recovered anatase TiO_(2) were adequately improved,and its specific surface area (SSA) and pore volume (PV) were 85 m^(2)·g^(-1)and 0.40 cm^(3)·g^(-1),respectively.The elements affecting catalytic abilities(arsenic and sodium) were also removed.The SCR catalyst was resynthesized using the recovered TiO_(2) as raw material,and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst.This study realized the sustainable recycling of anatase TiO_(2) from spent SCR catalyst.展开更多
Mesoporous activated carbons were prepared from direct coal liquefaction residue(CLR)by KOH activation method,and the experiments were carried out to investigate the effects of KOH/CLR ratio,solvent for mixing the CLR...Mesoporous activated carbons were prepared from direct coal liquefaction residue(CLR)by KOH activation method,and the experiments were carried out to investigate the effects of KOH/CLR ratio,solvent for mixing the CLR and KOH,and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition(CMD).The results showed that optimal KOH/CLR ratio of 2:1; solvent with higher solubility to KOH or the CLR,and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD.The resultant mesoporous carbons show higher and more stable activity than microporous carbons. Additionally,the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.展开更多
Objective: Extranodal involvement represents a peculiar presentation of diffuse large B-cell lymphoma(DLBCL). Previous studies have suggested that older patients are more prone to extranodal involvement. This study re...Objective: Extranodal involvement represents a peculiar presentation of diffuse large B-cell lymphoma(DLBCL). Previous studies have suggested that older patients are more prone to extranodal involvement. This study retrospectively addressed the distribution, prognostic value and treatment options of extranodal involvement in young patients with DLBCL.Methods: A total of 329 patients were enrolled according to the inclusion requirements. The effects of gender,extranodal involvement, age-adjusted international prognostic index(aa IPI), rituximab infusion and radiotherapy on patient outcomes were evaluated.Results: Among these patients, 59% presented extranodal involvement in 16 anatomic sites. More than one instance was linked to many poorer clinical characteristics and poorer survival compared with either nodal disease or one instance. In patients with one extranodal lesion, multivariate analysis revealed that the site of extranodal involvement, but not the aa IPI or rituximab infusion, was independently related to the outcome, and radiotherapy had a negative influence on survival.Conclusions: Extranodal involvement is common in younger patients and exhibits a ubiquitous distribution.The site of extranodal involvement is of strong prognostic significance. Radiotherapy for extranodal lesions does not improve patient outcomes.展开更多
As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves...As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study,the volume of fluid(VOF), mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier–Stokes/large eddy simulation(RANS/LES) turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian+RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF+LES method best matches the experimental measurement, while the mixture+LES method predicts the inception point of the air entrainment more accurately.展开更多
[Objectives]The paper was to understand the species and pathogenicity of the pathogen causing potato early blight in winter.[Methods]The occurrence of potato early blight was investigated in 5 winter potato growing ar...[Objectives]The paper was to understand the species and pathogenicity of the pathogen causing potato early blight in winter.[Methods]The occurrence of potato early blight was investigated in 5 winter potato growing areas in Yunnan Province.The disease samples were collected from two locations(Zhutang Village and Zhanai Village,Pu'er City)where the occurrence of early blight was severe.The pathogen was isolated and purified in laboratory and identified by morphological characteristics and phylogenetic analysis of ITS gene sequence.And it was further verified via re-inoculation by Koch's rules.The growth characteristics and pathogenicity of isolates in different seasons were analyzed with 4 strains of Alternaria isolated in spring(EYZ,EYAX,TA1 and TAC)as controls.[Results]Early blight occurred in varying degrees in the 5 winter potato growing areas,and the incidence of early blight was up to 100%in some plots in Lancang County,Pu'er City.A total of 35 strains of Alternaria were isolated from plots with high incidence,which were divided into two types according to colony morphology.The first type was round colonies with smooth edges and gray white fronts,and the second type was round colonies with rough edges and gray black fronts.Three strains LC1,LC2,LC3 of the first type and two strains ZT3 and ZT8 of the second type were selected and identified as Alternaria alternata through morphological and molecular identification.Re-inoculation test further confirmed that the pathogen was A.alternata.Meantime,it was found that the growth rate of colonies isolated in winter was relatively slow,and there was no significant difference between the pathogenicity of LC1 and TA1,but the pathogenicity of strains isolated in winter was generally higher than that isolated in spring.[Conclusions]It is confirmed that the pathogen causing potato early blight in winter is A.alternata in Yunnan Province.The results will lay a foundation for the research of pathogenesis,occurrence regularity and disease control of A.alternata in winter potato.展开更多
Noble metal nanoparticles are attractive catalytic materials on account of their novel optical,electrical and magnetic properties compared with bulk solids.Nanosized alloys attract considerable attentions due to the i...Noble metal nanoparticles are attractive catalytic materials on account of their novel optical,electrical and magnetic properties compared with bulk solids.Nanosized alloys attract considerable attentions due to the increasing demands,and outstanding chemical and physical properties via cooperative interactions for high performance catalysts.In this research,carbon-supported展开更多
目的研究“一步法”与序贯“二步法”腹腔镜手术治疗胆囊结石合并胆总管结石患者的整体疗效及术后并发症对比。方法纳入2020年5月至2022年5月期间收治的103例胆囊结石合并胆总管结石患者,根据治疗方法将其分为一步法组(n=48)与二步法组(...目的研究“一步法”与序贯“二步法”腹腔镜手术治疗胆囊结石合并胆总管结石患者的整体疗效及术后并发症对比。方法纳入2020年5月至2022年5月期间收治的103例胆囊结石合并胆总管结石患者,根据治疗方法将其分为一步法组(n=48)与二步法组(n=55),一步法组实施腹腔镜胆总管探查术(LCBDE)联合腹腔镜胆囊切除术(LC)治疗;二步法组实施内镜逆行胰胆管造影(ERCP)与内镜十二指肠乳头括约肌切开取石术(EST)联合LC治疗。将所有患者数据进行倾向性匹配评分(卡钳值为0.02)排除基线资料混杂因素影响,两组各获得46例基线资料可比的患者。数据采用SSPS 24.0软件分析,计数资料以[例(%)]表示,采用χ^(2)检验;计量资料以x±s表示,采用配对t检验或者LSD-t检验。P<0.05表示差异有统计学意义。结果两组患者手术期间一次性结石清除率(93.5% vs. 91.3%)、中转开腹率(0.0% vs. 2.2%)、结石残留率(6.5% vs. 8.7%)比及胃肠道功能比较,差异均无统计学意义(P>0.05),两组患者术后胃肠道功能改善用时比较差异无统计学意义(P>0.05);一步法组镇静剂使用率及住院时间均显著低于二步法组(P<0.05);两组患者手术期间并发症发生率(8.7% vs. 10.9%),差异无统计学意义(P>0.05)。结论LCBDE联合LC治疗胆囊结石合并胆总管结石,术后恢复更快,适用于年轻患者或结石较大患者,但对于老年患者或重度梗阻性黄疽患者,则可以采选ERCP/EST+LC治疗,因此临床应根据患者实际情况选择合适的微创治疗方案。展开更多
The present study investigated the influence of high temperature oxidation and reduction pretreatments on the leaching rate of Panzhihua ilmenite.The as-pretreated ilmenite was leached with 20%HCl at 105℃.The leachin...The present study investigated the influence of high temperature oxidation and reduction pretreatments on the leaching rate of Panzhihua ilmenite.The as-pretreated ilmenite was leached with 20%HCl at 105℃.The leaching process was controlled by the phases and microstructures that evolved during the pretreatment processes.The leaching kinetics of pure hematite,ilmenite and pseudobrookite were characterized to clarify the phase effect on the iron-leaching rate;the rate of iron leaching occurs in the following order in the HCl solution:hematite(ferric iron) > ilmenite(ferrous iron)>>pseudobrookite(ferric iron).Therefore,the often-cited notion that ferrous iron dissolves faster in HCl solutions than ferric iron when explaining the pretreatment effects is inaccurate.Moreover,the oxidation pretreatment(at 600-1000℃ for 4 h)cannot destroy the dense structure of the Panzhihua ilmenite.Therefore,the influence exerted by the oxidation on the leaching process is primarily determined by the phase change;oxidation at 600 and 700℃slightly increased the rate of iron leaching because the ilmenite was transformed into hematite,while the oxidation at 900-1000℃ significantly reduced the rate of iron leaching because a pseudobrookite phase formed.The reduction effect was subsequently investigated;the as-oxidized ilmenite was reduced under H_2 at 750℃ for 30 min.The reduction significantly accelerated the rate of subsequent iron leaching such that nearly all of the iron had dissolved after leaching for 2h in 20%HCl at 105℃.This enhanced iron-leaching rate is mainly attributed to the cracks and holes that formed during the reduction process.展开更多
The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance th...The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance the capacity of communication. However, the lack of a compact, efficient, and integrated OAM(de)multiplexer prevents it from being widely applied. By attaching vortex gratings onto the facets of a few-mode fiber, we demonstrate an integrated fiber-based OAM(de)multiplexer. A vortex grating fabricated on the fiber facet enables the direct multiplexing of OAM states at one port and the demultiplexing of OAM states at the other port. The measured bit error rate of the carrier signal after propagating through a 5-km few-mode fiber confirms the validity and effectiveness of the proposed approach. The scheme offers advantages in future high-capacity OAM communication based on optical fiber.展开更多
Measurements of peroxyacetyl nitrate(PAN) were made at a Beijing urban site each August from2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3(2005) to 11.7 ...Measurements of peroxyacetyl nitrate(PAN) were made at a Beijing urban site each August from2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3(2005) to 11.7 μg/m3(2007); however, it decreased rapidly in 2008(4.1 μg/m3).Generally, the variation over the 5 years showed a rise in the first part of the study period,followed by a decline. We considered two categories of local and regional air masses in this study, which revealed that the PAN concentration in Beijing was affected mainly by southeastern air masses. The August PAN variation was influenced predominantly by local air masses in 2005,but by 2009 regional air masses had become more important. This study showed the level and variation of PAN in the month of August in 5 consecutive years for the first time, and proved that control measures are useful in decreasing photochemical pollution; hence, these measures are probably feasible for other megacities too. Furthermore, this method of analyzing regional and local impacts might be useful for other studies as well.展开更多
1-Chloro-1,1-difluoroethane(HCFC-142b)was both ozone depleting substance under restriction of the Montreal Protocol on Substances that Deplete the Ozone Layer(Montreal Protocol)and potent greenhouse gas with high GWP....1-Chloro-1,1-difluoroethane(HCFC-142b)was both ozone depleting substance under restriction of the Montreal Protocol on Substances that Deplete the Ozone Layer(Montreal Protocol)and potent greenhouse gas with high GWP.Controlling its emissions in China will contribute to both mitigating climate change and protecting ozone.A national emission inventory of HCFC-142b for China during 2000–2012 was established and projected to2050 based on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the Montreal Protocol,showing that(i)in contrast to the downward trend revealed by existing researches,HCFC-142b emissions kept increasing from 0.1 kt/y in 2000 to the peak of 14.4 kt/y in2012,making China a crucial contributor to global HCFC-142b emissions and(ii)for future emission projections,a continuous increase from 14.9 kt/y in 2013 to 97.2 kt/y in2050 was anticipated under the business-as-usual(BAU)scenarios,while a reduction of about 90%of the projected BAU emissions would be obtained by fulfilling the Montreal Protocol,namely an accumulative mitigation of 1578kt HCFC-142b from 2013 to 2050,equal to 103 kt ODP and 3504 Tg CO2emissions.Emissions from each province in 2012 were also estimated to identify key emission areas.Among the 31 mainland provinces in China(Hong Kong,Macao,and Taiwan were not included),Jiangsu,Zhejiang,Shandong,and Guangdong had the highest emission ratesin 2012(2.06,1.85,1.52,and 1.04 kt/y,respectively);Zhejiang,Jiangsu,and Shanghai exhibit the strongest emission strength(0.83,0.59,and 0.54 t/km2,respectively),much higher than the average national level of 0.33t/km2.展开更多
Striking effects are expected in solid-solution alloying,which offers enormous possibilities for various applications,especially in industrial catalysis.However,phase diagrams have revealed that a wide range of metall...Striking effects are expected in solid-solution alloying,which offers enormous possibilities for various applications,especially in industrial catalysis.However,phase diagrams have revealed that a wide range of metallic elements are immiscible with each other even above their melting points.Achieving such unknown alloying between different immiscible metallic elements is highly desirable but challenging.Here,for the first time,by using an innovative solid ligand-assisted approach,we achieve the solid-solution alloying between the bulk-immiscible Au and Rh in plenty of clean,ultrafine(∼1.6 nm)and highly dispersed nanoclusters.The solid-solution alloying of immiscible Au and Rh significantly enhances their catalytic performance toward the hydrogen evolution from formic acid in contrast to the monometallic Au and Rh nanoclusters.Moreover,the resultant binary solid-solution nanoclusters are stable without any segregation during catalytic reactions.The approach demonstrated here for homogeneously mixing the immiscible metals at the atomic scale will benefit the creation of advanced alloys and their catalytic applications in future.展开更多
Peroxyacyl nitrates(PANs) are important secondary pollutants in ground-level atmosphere.Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during speci...Peroxyacyl nitrates(PANs) are important secondary pollutants in ground-level atmosphere.Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during specific pollution events. In this study, four models based on the back-propagation(BP) artificial neural network(ANN) and multiple linear regression(MLR) methods were used to predict the hourly average PAN concentrations at Peking University, Beijing, in 2014. The model inputs were atmospheric pollutant data and meteorological parameters. Model 3 using a BP-ANN based on the original variables achieved the best prediction results among the four models, with a correlation coefficient(R) of 0.7089, mean bias error of -0.0043 ppb, mean absolute error of 0.4836?ppb, root mean squared error of 0.5320?ppb, and Willmott's index of agreement of 0.8214. Based on a comparison of the performance indices of the MLR and BP-ANN models, we concluded that the BP-ANN model was able to capture the highly non-linear relationships between PAN concentration and the conventional atmospheric pollutant and meteorological parameters,providing more accurate results than the traditional MLR models did, with a markedly higher goodness of R. The selected meteorological and atmospheric pollutant parameters described a sufficient amount of PAN variation, and thus provided satisfactory prediction results. More specifically, the BP-ANN model performed very well for capturing the variation pattern when PAN concentrations were low. The findings of this study address some of the existing knowledge gaps in this research field and provide a theoretical basis for future regional air pollution control.展开更多
基金The project supported by the National Key Research and Development Program of China(Grant No.2018YFA0305703)Science Challenge Project(Grant No.TZ2016001)the National Natural Science Foundation of China(Grant Nos.U1930401 and 11874075)。
文摘High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for studying delicate phase transitions caused by complex interactions in Mott insulators.With time-resolved transient reflectivity measurements,we identified the new phases in the spin–orbit Mott insulator Sr_(3)Ir_(2)O_7 at 300 K that was previously unidentified using conventional approaches such as x-ray diffraction.Significant pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity?R/R reveal the changes of electronic structure caused by lattice distortions,and reflect the critical phenomena of phase transitions.Our findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators.
基金finally supported by the National Natural Science Foundation of China(52174390,U1810205)Innovation Academy for Green Manufacture of the Chinese Academy of Sciences China(IAGM2022D04)Strategic Priority Research Program of the Chinese Academy of Sciences China(XDA21040601)。
文摘Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.
基金supported by the National Natural Science Foundation of China (52274411)the National Natural Science Foundation of China (51904287)the Innovation Academy for Green Manufacture,Chinese Academy of Sciences (IAGM2022D11)。
文摘The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste.A novel process to recover anatase titanium dioxide (TiO_(2)) from spent SCR catalysts was proposed.The process included alkali (NaOH) hydrothermal treatment,sulfuric acid washing,and calcination.Anatase TiO_(2) in spent SCR catalyst was reconstructed by forming Na_(2)Ti_(2)O_(4)(OH)_(2) nanosheet during NaOH hydrothermal treatment and H_(2)Ti_(2)O_(4)(OH)_(2) during sulfuric acid washing.Anatase TiO_(2) was recovered by decomposing H_(2)Ti_(2)O_(4)(OH)_(2) during calcination.The surface pore properties of the recovered anatase TiO_(2) were adequately improved,and its specific surface area (SSA) and pore volume (PV) were 85 m^(2)·g^(-1)and 0.40 cm^(3)·g^(-1),respectively.The elements affecting catalytic abilities(arsenic and sodium) were also removed.The SCR catalyst was resynthesized using the recovered TiO_(2) as raw material,and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst.This study realized the sustainable recycling of anatase TiO_(2) from spent SCR catalyst.
基金supported by the National Natural Science Foundation of China(No.20906009)the Key Program Project of Joint Fund of Coal Research by NSFC and Shenhua Group(No.51134014)+2 种基金the Fundamental Research Funds for the Central Universities(No.DUT12JN05)the National Basic Research Program of China(973Program)the Ministry of Science and Technology,China(No.2011CB201301)
文摘Mesoporous activated carbons were prepared from direct coal liquefaction residue(CLR)by KOH activation method,and the experiments were carried out to investigate the effects of KOH/CLR ratio,solvent for mixing the CLR and KOH,and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition(CMD).The results showed that optimal KOH/CLR ratio of 2:1; solvent with higher solubility to KOH or the CLR,and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD.The resultant mesoporous carbons show higher and more stable activity than microporous carbons. Additionally,the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.
基金supported by the National Nature Science Foundation of China (No. 81071938, 81470365)
文摘Objective: Extranodal involvement represents a peculiar presentation of diffuse large B-cell lymphoma(DLBCL). Previous studies have suggested that older patients are more prone to extranodal involvement. This study retrospectively addressed the distribution, prognostic value and treatment options of extranodal involvement in young patients with DLBCL.Methods: A total of 329 patients were enrolled according to the inclusion requirements. The effects of gender,extranodal involvement, age-adjusted international prognostic index(aa IPI), rituximab infusion and radiotherapy on patient outcomes were evaluated.Results: Among these patients, 59% presented extranodal involvement in 16 anatomic sites. More than one instance was linked to many poorer clinical characteristics and poorer survival compared with either nodal disease or one instance. In patients with one extranodal lesion, multivariate analysis revealed that the site of extranodal involvement, but not the aa IPI or rituximab infusion, was independently related to the outcome, and radiotherapy had a negative influence on survival.Conclusions: Extranodal involvement is common in younger patients and exhibits a ubiquitous distribution.The site of extranodal involvement is of strong prognostic significance. Radiotherapy for extranodal lesions does not improve patient outcomes.
基金supported by the Guangdong Special Research Fund of Public Welfare and Capacity Building(2015A020216008)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)
文摘As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study,the volume of fluid(VOF), mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier–Stokes/large eddy simulation(RANS/LES) turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian+RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF+LES method best matches the experimental measurement, while the mixture+LES method predicts the inception point of the air entrainment more accurately.
基金Major Science and Technology Special Plan of Yunnan Department of Science and Technology(202102AE090018)Key Research and Development Program of Hainan Province(ZDYF2021XDNY291).
文摘[Objectives]The paper was to understand the species and pathogenicity of the pathogen causing potato early blight in winter.[Methods]The occurrence of potato early blight was investigated in 5 winter potato growing areas in Yunnan Province.The disease samples were collected from two locations(Zhutang Village and Zhanai Village,Pu'er City)where the occurrence of early blight was severe.The pathogen was isolated and purified in laboratory and identified by morphological characteristics and phylogenetic analysis of ITS gene sequence.And it was further verified via re-inoculation by Koch's rules.The growth characteristics and pathogenicity of isolates in different seasons were analyzed with 4 strains of Alternaria isolated in spring(EYZ,EYAX,TA1 and TAC)as controls.[Results]Early blight occurred in varying degrees in the 5 winter potato growing areas,and the incidence of early blight was up to 100%in some plots in Lancang County,Pu'er City.A total of 35 strains of Alternaria were isolated from plots with high incidence,which were divided into two types according to colony morphology.The first type was round colonies with smooth edges and gray white fronts,and the second type was round colonies with rough edges and gray black fronts.Three strains LC1,LC2,LC3 of the first type and two strains ZT3 and ZT8 of the second type were selected and identified as Alternaria alternata through morphological and molecular identification.Re-inoculation test further confirmed that the pathogen was A.alternata.Meantime,it was found that the growth rate of colonies isolated in winter was relatively slow,and there was no significant difference between the pathogenicity of LC1 and TA1,but the pathogenicity of strains isolated in winter was generally higher than that isolated in spring.[Conclusions]It is confirmed that the pathogen causing potato early blight in winter is A.alternata in Yunnan Province.The results will lay a foundation for the research of pathogenesis,occurrence regularity and disease control of A.alternata in winter potato.
文摘Noble metal nanoparticles are attractive catalytic materials on account of their novel optical,electrical and magnetic properties compared with bulk solids.Nanosized alloys attract considerable attentions due to the increasing demands,and outstanding chemical and physical properties via cooperative interactions for high performance catalysts.In this research,carbon-supported
文摘目的研究“一步法”与序贯“二步法”腹腔镜手术治疗胆囊结石合并胆总管结石患者的整体疗效及术后并发症对比。方法纳入2020年5月至2022年5月期间收治的103例胆囊结石合并胆总管结石患者,根据治疗方法将其分为一步法组(n=48)与二步法组(n=55),一步法组实施腹腔镜胆总管探查术(LCBDE)联合腹腔镜胆囊切除术(LC)治疗;二步法组实施内镜逆行胰胆管造影(ERCP)与内镜十二指肠乳头括约肌切开取石术(EST)联合LC治疗。将所有患者数据进行倾向性匹配评分(卡钳值为0.02)排除基线资料混杂因素影响,两组各获得46例基线资料可比的患者。数据采用SSPS 24.0软件分析,计数资料以[例(%)]表示,采用χ^(2)检验;计量资料以x±s表示,采用配对t检验或者LSD-t检验。P<0.05表示差异有统计学意义。结果两组患者手术期间一次性结石清除率(93.5% vs. 91.3%)、中转开腹率(0.0% vs. 2.2%)、结石残留率(6.5% vs. 8.7%)比及胃肠道功能比较,差异均无统计学意义(P>0.05),两组患者术后胃肠道功能改善用时比较差异无统计学意义(P>0.05);一步法组镇静剂使用率及住院时间均显著低于二步法组(P<0.05);两组患者手术期间并发症发生率(8.7% vs. 10.9%),差异无统计学意义(P>0.05)。结论LCBDE联合LC治疗胆囊结石合并胆总管结石,术后恢复更快,适用于年轻患者或结石较大患者,但对于老年患者或重度梗阻性黄疽患者,则可以采选ERCP/EST+LC治疗,因此临床应根据患者实际情况选择合适的微创治疗方案。
基金financial support from the National Basic Research Program of China(grant No. 2013CB632603)the Chinese Academy of Sciences(project No.KGCX2-EW215)
文摘The present study investigated the influence of high temperature oxidation and reduction pretreatments on the leaching rate of Panzhihua ilmenite.The as-pretreated ilmenite was leached with 20%HCl at 105℃.The leaching process was controlled by the phases and microstructures that evolved during the pretreatment processes.The leaching kinetics of pure hematite,ilmenite and pseudobrookite were characterized to clarify the phase effect on the iron-leaching rate;the rate of iron leaching occurs in the following order in the HCl solution:hematite(ferric iron) > ilmenite(ferrous iron)>>pseudobrookite(ferric iron).Therefore,the often-cited notion that ferrous iron dissolves faster in HCl solutions than ferric iron when explaining the pretreatment effects is inaccurate.Moreover,the oxidation pretreatment(at 600-1000℃ for 4 h)cannot destroy the dense structure of the Panzhihua ilmenite.Therefore,the influence exerted by the oxidation on the leaching process is primarily determined by the phase change;oxidation at 600 and 700℃slightly increased the rate of iron leaching because the ilmenite was transformed into hematite,while the oxidation at 900-1000℃ significantly reduced the rate of iron leaching because a pseudobrookite phase formed.The reduction effect was subsequently investigated;the as-oxidized ilmenite was reduced under H_2 at 750℃ for 30 min.The reduction significantly accelerated the rate of subsequent iron leaching such that nearly all of the iron had dissolved after leaching for 2h in 20%HCl at 105℃.This enhanced iron-leaching rate is mainly attributed to the cracks and holes that formed during the reduction process.
基金National Natural Science Foundation of China(NSFC)(U1701661,61427819,61525502,61435006,11604218,61601199,61775085,61405121)Science and Technology Innovation Commission of Shenzhen(KQCS2015032416183980,KQJSCX20160226193555889,KQTD2015071016560101,KQTD2017033011044403,ZDSYS201703031605029)+2 种基金Leading Talents of Guangdong Province(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2017A030313351)National Key Basic Research Program of China(973)(2015CB352004)
文摘The quickly increasing data transfer load requires an urgent revolution in current optical communication. Orbital angular momentum(OAM) multiplexing is a potential candidate with its ability to considerably enhance the capacity of communication. However, the lack of a compact, efficient, and integrated OAM(de)multiplexer prevents it from being widely applied. By attaching vortex gratings onto the facets of a few-mode fiber, we demonstrate an integrated fiber-based OAM(de)multiplexer. A vortex grating fabricated on the fiber facet enables the direct multiplexing of OAM states at one port and the demultiplexing of OAM states at the other port. The measured bit error rate of the carrier signal after propagating through a 5-km few-mode fiber confirms the validity and effectiveness of the proposed approach. The scheme offers advantages in future high-capacity OAM communication based on optical fiber.
基金supported by the Beijing Council of Science and Technology (Nos. HB200504-6, HB200504-2)the Natural Science Fund Project of the Beijing Municipal Government (No. 8072014)+1 种基金the National High Technology Development Plan (863 Project) of China (No. 2006AA06A301)supported by the special fund provided by the State Key Joint Laboratory of Environmental Simulation and Pollution Control (14Y04ESPCP), Peking University
文摘Measurements of peroxyacetyl nitrate(PAN) were made at a Beijing urban site each August from2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3(2005) to 11.7 μg/m3(2007); however, it decreased rapidly in 2008(4.1 μg/m3).Generally, the variation over the 5 years showed a rise in the first part of the study period,followed by a decline. We considered two categories of local and regional air masses in this study, which revealed that the PAN concentration in Beijing was affected mainly by southeastern air masses. The August PAN variation was influenced predominantly by local air masses in 2005,but by 2009 regional air masses had become more important. This study showed the level and variation of PAN in the month of August in 5 consecutive years for the first time, and proved that control measures are useful in decreasing photochemical pollution; hence, these measures are probably feasible for other megacities too. Furthermore, this method of analyzing regional and local impacts might be useful for other studies as well.
基金supported by the State KeyLaboratory Program of China(09Z02ESPCP)
文摘1-Chloro-1,1-difluoroethane(HCFC-142b)was both ozone depleting substance under restriction of the Montreal Protocol on Substances that Deplete the Ozone Layer(Montreal Protocol)and potent greenhouse gas with high GWP.Controlling its emissions in China will contribute to both mitigating climate change and protecting ozone.A national emission inventory of HCFC-142b for China during 2000–2012 was established and projected to2050 based on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the Montreal Protocol,showing that(i)in contrast to the downward trend revealed by existing researches,HCFC-142b emissions kept increasing from 0.1 kt/y in 2000 to the peak of 14.4 kt/y in2012,making China a crucial contributor to global HCFC-142b emissions and(ii)for future emission projections,a continuous increase from 14.9 kt/y in 2013 to 97.2 kt/y in2050 was anticipated under the business-as-usual(BAU)scenarios,while a reduction of about 90%of the projected BAU emissions would be obtained by fulfilling the Montreal Protocol,namely an accumulative mitigation of 1578kt HCFC-142b from 2013 to 2050,equal to 103 kt ODP and 3504 Tg CO2emissions.Emissions from each province in 2012 were also estimated to identify key emission areas.Among the 31 mainland provinces in China(Hong Kong,Macao,and Taiwan were not included),Jiangsu,Zhejiang,Shandong,and Guangdong had the highest emission ratesin 2012(2.06,1.85,1.52,and 1.04 kt/y,respectively);Zhejiang,Jiangsu,and Shanghai exhibit the strongest emission strength(0.83,0.59,and 0.54 t/km2,respectively),much higher than the average national level of 0.33t/km2.
文摘Striking effects are expected in solid-solution alloying,which offers enormous possibilities for various applications,especially in industrial catalysis.However,phase diagrams have revealed that a wide range of metallic elements are immiscible with each other even above their melting points.Achieving such unknown alloying between different immiscible metallic elements is highly desirable but challenging.Here,for the first time,by using an innovative solid ligand-assisted approach,we achieve the solid-solution alloying between the bulk-immiscible Au and Rh in plenty of clean,ultrafine(∼1.6 nm)and highly dispersed nanoclusters.The solid-solution alloying of immiscible Au and Rh significantly enhances their catalytic performance toward the hydrogen evolution from formic acid in contrast to the monometallic Au and Rh nanoclusters.Moreover,the resultant binary solid-solution nanoclusters are stable without any segregation during catalytic reactions.The approach demonstrated here for homogeneously mixing the immiscible metals at the atomic scale will benefit the creation of advanced alloys and their catalytic applications in future.
基金supported by the "State Key R&D Program" of China.(Nos.2017YFC0212400,2016YFC0202200)
文摘Peroxyacyl nitrates(PANs) are important secondary pollutants in ground-level atmosphere.Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during specific pollution events. In this study, four models based on the back-propagation(BP) artificial neural network(ANN) and multiple linear regression(MLR) methods were used to predict the hourly average PAN concentrations at Peking University, Beijing, in 2014. The model inputs were atmospheric pollutant data and meteorological parameters. Model 3 using a BP-ANN based on the original variables achieved the best prediction results among the four models, with a correlation coefficient(R) of 0.7089, mean bias error of -0.0043 ppb, mean absolute error of 0.4836?ppb, root mean squared error of 0.5320?ppb, and Willmott's index of agreement of 0.8214. Based on a comparison of the performance indices of the MLR and BP-ANN models, we concluded that the BP-ANN model was able to capture the highly non-linear relationships between PAN concentration and the conventional atmospheric pollutant and meteorological parameters,providing more accurate results than the traditional MLR models did, with a markedly higher goodness of R. The selected meteorological and atmospheric pollutant parameters described a sufficient amount of PAN variation, and thus provided satisfactory prediction results. More specifically, the BP-ANN model performed very well for capturing the variation pattern when PAN concentrations were low. The findings of this study address some of the existing knowledge gaps in this research field and provide a theoretical basis for future regional air pollution control.
