The semi-solid slurry of an A356 Al alloy, which was grain-fined by yttrium, was manufactured by low temperature pouring, The effects of grain-refining on the morphology and the grain size of the primary α phase in t...The semi-solid slurry of an A356 Al alloy, which was grain-fined by yttrium, was manufactured by low temperature pouring, The effects of grain-refining on the morphology and the grain size of the primary α phase in the semi-solid A356 Al alloy were researched. The results indicate that the semi-solid A356 AI alloy with particle-like and rosette-like primary α-Al can be prepared by low temperature pouring from a liquid grain-refined A356 alloy. The grain size and particle morphology of primary α-Al in the A356 Al alloy are markedly improved by the addition of 0.5 wt,% Y. The fining mechanism of Y on the morphology and grain size of the primary α-Al in the semi-solid A356 Al alloy was delved.展开更多
Exquisitely preserved three-dimensional soft- bodied fossils and typical Orsten-type preservation have been found from the strata of Middle and Late Cambrian in western Hunan, China. A preliminary description is provi...Exquisitely preserved three-dimensional soft- bodied fossils and typical Orsten-type preservation have been found from the strata of Middle and Late Cambrian in western Hunan, China. A preliminary description is provided for Hesslandona sp. (Phosphatocopida, Crustacea, Arthro-poda) and Skara sp. (Skaracarida, Crustaceam, Arthropoda). The scientific significance of Orsten-type preservation and prospects for future work on these fossils from Hunan are outlined.展开更多
An Al_2O_(3f)/Al-4.5Cu composite was made by squeeze casting. The solutesegregation in the composite at different cooling rates was studied. The results indicate that theprimary crystal of Al-4.5Cu alloy nucleates and...An Al_2O_(3f)/Al-4.5Cu composite was made by squeeze casting. The solutesegregation in the composite at different cooling rates was studied. The results indicate that theprimary crystal of Al-4.5Cu alloy nucleates and grows in the interstice between fibers. The fibersurface cannot serve as site for the heterogeneous nucleation of a primary dendrite. There exists anincreasing Cu concentration gradient from the center of the interstice between fibers to theinterface or the grain boundaries. There are the eutectic phases around the fibers. The solutesegregation in the matrix increases with the cooling rate rising. The amount of eutectic phasesfollowed by imbalance crystalline can be numerically calculated with Clyne-Kurz formula.展开更多
Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopor...Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), N_2 adsorption/desorption experiments, powder X-ray diffraction(PXRD), and thermogravimetric analysis(TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at p H 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO_3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).展开更多
In this paper, the adsorption-desorption variations of trivalent La, Ce, Y and mixed rare earths are discussed. The curves of pH-rare earth element adsorption were very well fitted to the equation: InD =a+b pH. The se...In this paper, the adsorption-desorption variations of trivalent La, Ce, Y and mixed rare earths are discussed. The curves of pH-rare earth element adsorption were very well fitted to the equation: InD =a+b pH. The selectivity of RE (rare earth element) ions by the samples decreased in the following order: Ce> RE> La> Y, but the sequences were: La> Ce> Y on kaolinite and Y> La on amorphous iron oxide. Since the trivalent RE ions existed in the form of RE(OH)2+ in the solutions from pH < 5.45 to 7.0, the ratio of H+ displaced to RE3+ adsorbed in micromole was proposed to be about 2. The specific adsorption mechanism for RE was proposed to be that the RE ions complexed with oxide surface and the ion-surface complex of Ce3+ promoted oxidization on Mn hydroxide.展开更多
A method determining di-and tri-valeht cobalt extracted from soils with EDTA·2HOAc·NH4OAc solution (pH 4.65) was developed based on the difference of the stability constants of Co(II)EDTA and Co(III)EDTA. An...A method determining di-and tri-valeht cobalt extracted from soils with EDTA·2HOAc·NH4OAc solution (pH 4.65) was developed based on the difference of the stability constants of Co(II)EDTA and Co(III)EDTA. Analytical results indicated that soil cobalt existed in both two oxidation states, i. e. , di-and tri-valent cobalt. Extractable di-valent cobalt in 60 soil samples collected from various soils in China ranged from 0.02 ppm to 3.54 ppm, with the mean of 0.62 ppm, and extractable tri-valent cobalt from 0.04 ppm to 27.65 ppm, with the mean of 2.93 ppm.展开更多
Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures ...Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures up to 200 deg C increase with an addition of Nd.Generally, the most significant improvement in the tensile properties is attained at 100 deg C. Thepresence of Mg12Nd is proved by X-ray diffraction. Microstructural observations reveal that theaddition of Nd can lead to the dispersion-strengthening. Due to the presence of Mg12Nd, the slidingof grain boundaries is restrained and the strength of the alloy is enhanced. It can be seen from thetensile fractographs that the fracture surfaces exhibit the mixed fracture characteristics, andless brittle fracture is observed with increasing the temperature. Quasi-cleavage fracture isthought as the main fracture mode. TEM observations expose the formation of dislocation network,slip lines and dislocation pile-ups.展开更多
The Frequency-Coded Pulse (FCP) signal has good performance of range and Doppler resolution. This paper first gives the mathematical expression of the ambiguity function for FCP signals, and then presents a coding rul...The Frequency-Coded Pulse (FCP) signal has good performance of range and Doppler resolution. This paper first gives the mathematical expression of the ambiguity function for FCP signals, and then presents a coding rule for optimizing FCP signal. The genetic algorithm is presented to solve this kind of problem for optimizing codes. Finally, an example for optimizing calculation is illustrated and the optimized frequency coding results are given with the code length N=64 and N=128 respectively.展开更多
Based on 2-dimensional vertically governing equations of salt water intrusion at estuaries, a method is obtained, which can predict quantitatively current velocity and salinity distribution along depth when the intrus...Based on 2-dimensional vertically governing equations of salt water intrusion at estuaries, a method is obtained, which can predict quantitatively current velocity and salinity distribution along depth when the intrusion occurs. The volume-controlling method proposed by Patanker and Spalding is used to form the computational pattern and the Power- Law Scheme is used as the diversion pattern of the diffusion term. The comparison between the computational results and the measured ones gives a satisfactory agreement.展开更多
The operational performance of a full scale subsurface flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD 5/COD mean ratio of 0 33 at Shatian, Shenzhen City was studied. ...The operational performance of a full scale subsurface flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD 5/COD mean ratio of 0 33 at Shatian, Shenzhen City was studied. The constructed wetland system consists of screens, sump, pumping station, and primary settling basin, facultative pond, first stage wetland and secondary stage wetland. The designed treatment capacity is 5000 m 3/d, and the actual influent flow is in the range of <2000 to >10000 m 3/d. Under normal operational conditions, the final effluent quality well met the National Integrated Wastewater Discharge Standard(GB 8978\_1996), with the following parameters(mean values): COD 33 90 mg/L, BOD 5 7.65 mg/L, TSS 7.92 mg/L, TN 9.11 mg/L and TP 0 56 mg/L. Seven species of plants were selected to grow in the wetland: Reed, Sweetcane flower Silvergrass, Great Bulrush, Powdery Thalia and Canna of three colours. The growing season is a whole year round. The seasonal discrepancy could be observed and the plants growing in the wetland are vulnerable to lower temperature in winter. The recycling of the effluent in the first stage of the wetland system is an effective measure to improve the performance of the wetland system. The insufficient DO value in the wetland system not only had significant effect on pollutants removal in the wetland, but also was unfavourable to plant growth. The recycling of effluent to the inlet of wetland system and artificial pond to increase DO value of influent to the wetland is key to operate the subsurface constructed wetland steadily and effectively.展开更多
背景与目的:对于肝门部胆管癌(HCCA)而言,R0切除率仍然很低。目前对术前评估、术前胆道引流、门静脉栓塞、手术切除范围、手术方式、血管切除、淋巴结清扫、化疗等问题仍有很多争议。R0切除被认为是HCCA患者获取长期生存的最重要的治疗...背景与目的:对于肝门部胆管癌(HCCA)而言,R0切除率仍然很低。目前对术前评估、术前胆道引流、门静脉栓塞、手术切除范围、手术方式、血管切除、淋巴结清扫、化疗等问题仍有很多争议。R0切除被认为是HCCA患者获取长期生存的最重要的治疗手段。笔者总结HCCA的治疗体会,并分析不同术式的有效性及近远期疗效。方法:回顾性分析2015年1月—2020年1月行手术治疗的44例HCCA患者的临床资料。结果:44例患者中,Bismuth-Corlette分型I型5例,II型7例,IIIa型8例,IIIb型13例,IV型11例;29例行半肝/扩大半肝+全尾叶切除(联合半肝切除),13例行肝门部/围肝门区+全尾叶切除(围肝门切除),术中包括门静脉部分切除修补2例,门静脉切除重建2例,肝动脉切除重建2例,另2例因肿瘤转移无法切除行T管引流。全组均完成手术,无手术死亡。术后病理结果显示,镜下切缘阴性(R0)切除37例(联合半肝切除组26例,围肝门切除组11例),镜下切缘阳性(R1)切除5例(半肝切除2例、围肝门切除3例)。临床指标分析结果显示,联合半肝切除组的手术时间(240.4 min vs.358.1 min)、术中出血量(705.5 mL vs.809.9 mL)明显少于围肝门切除组,肿瘤标本切缘阳性率(6.9%vs.23.1%)明显低于围肝门切除组(均P<0.05);生存分析结果显示,联合半肝切除组术后与无复发生存期及1年累积生存率明显优于围肝门切除组(均P<0.05)。结论:根治性R0切除是HCCA患者可能获得治愈的唯一方法,与围肝门切除术比较,联合半肝、尾状叶切除的大范围肝切除术,能提高R0切除率,改善无复发生存期及1年生存率。术前精确评估、合理的围手术期治疗、选择个体化的手术方案可提高HCCA的疗效。展开更多
基金the Natural Science Foundation of Jiangxi Province, China (No. 0650047)
文摘The semi-solid slurry of an A356 Al alloy, which was grain-fined by yttrium, was manufactured by low temperature pouring, The effects of grain-refining on the morphology and the grain size of the primary α phase in the semi-solid A356 Al alloy were researched. The results indicate that the semi-solid A356 AI alloy with particle-like and rosette-like primary α-Al can be prepared by low temperature pouring from a liquid grain-refined A356 alloy. The grain size and particle morphology of primary α-Al in the A356 Al alloy are markedly improved by the addition of 0.5 wt,% Y. The fining mechanism of Y on the morphology and grain size of the primary α-Al in the semi-solid A356 Al alloy was delved.
基金supported by the National Natural Science Foundation of China(Grant Nos.40372001 and 40072007 to DXP)Laboratory of Paleobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences(Grant No.023106 to XPD)+2 种基金funded by the Research Fund for Doctoral Program of High Education(Grant No.2000000127 to XPD)the Funding of Peking University(to XPD),the Royal Society(to XPD and PCJD),the international cooperation program of NSFC(to PCJD and XPD)the Natural Environment Research Council(Grant Nos.NER/M/S/2002/00069 and NE/C511256/1 to PCJD).
文摘Exquisitely preserved three-dimensional soft- bodied fossils and typical Orsten-type preservation have been found from the strata of Middle and Late Cambrian in western Hunan, China. A preliminary description is provided for Hesslandona sp. (Phosphatocopida, Crustacea, Arthro-poda) and Skara sp. (Skaracarida, Crustaceam, Arthropoda). The scientific significance of Orsten-type preservation and prospects for future work on these fossils from Hunan are outlined.
文摘An Al_2O_(3f)/Al-4.5Cu composite was made by squeeze casting. The solutesegregation in the composite at different cooling rates was studied. The results indicate that theprimary crystal of Al-4.5Cu alloy nucleates and grows in the interstice between fibers. The fibersurface cannot serve as site for the heterogeneous nucleation of a primary dendrite. There exists anincreasing Cu concentration gradient from the center of the interstice between fibers to theinterface or the grain boundaries. There are the eutectic phases around the fibers. The solutesegregation in the matrix increases with the cooling rate rising. The amount of eutectic phasesfollowed by imbalance crystalline can be numerically calculated with Clyne-Kurz formula.
基金supported by the National Natural Science Foundation of China (11275219, 11275090, U1432103)the “Strategic Priority Research program” of the Chinese Academy of Sciences (XDA030104)+1 种基金the State Key Laboratory of NBC Protection for Civilian (SKLNB201412)the Scientific Research Fund of Hunan Provincial Education Department (12A116)
文摘Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), N_2 adsorption/desorption experiments, powder X-ray diffraction(PXRD), and thermogravimetric analysis(TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at p H 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO_3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).
文摘In this paper, the adsorption-desorption variations of trivalent La, Ce, Y and mixed rare earths are discussed. The curves of pH-rare earth element adsorption were very well fitted to the equation: InD =a+b pH. The selectivity of RE (rare earth element) ions by the samples decreased in the following order: Ce> RE> La> Y, but the sequences were: La> Ce> Y on kaolinite and Y> La on amorphous iron oxide. Since the trivalent RE ions existed in the form of RE(OH)2+ in the solutions from pH < 5.45 to 7.0, the ratio of H+ displaced to RE3+ adsorbed in micromole was proposed to be about 2. The specific adsorption mechanism for RE was proposed to be that the RE ions complexed with oxide surface and the ion-surface complex of Ce3+ promoted oxidization on Mn hydroxide.
文摘A method determining di-and tri-valeht cobalt extracted from soils with EDTA·2HOAc·NH4OAc solution (pH 4.65) was developed based on the difference of the stability constants of Co(II)EDTA and Co(III)EDTA. Analytical results indicated that soil cobalt existed in both two oxidation states, i. e. , di-and tri-valent cobalt. Extractable di-valent cobalt in 60 soil samples collected from various soils in China ranged from 0.02 ppm to 3.54 ppm, with the mean of 0.62 ppm, and extractable tri-valent cobalt from 0.04 ppm to 27.65 ppm, with the mean of 2.93 ppm.
基金This project is supported by Provincial Natural Science Foundation of Liaoning (No.002015)
文摘Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures up to 200 deg C increase with an addition of Nd.Generally, the most significant improvement in the tensile properties is attained at 100 deg C. Thepresence of Mg12Nd is proved by X-ray diffraction. Microstructural observations reveal that theaddition of Nd can lead to the dispersion-strengthening. Due to the presence of Mg12Nd, the slidingof grain boundaries is restrained and the strength of the alloy is enhanced. It can be seen from thetensile fractographs that the fracture surfaces exhibit the mixed fracture characteristics, andless brittle fracture is observed with increasing the temperature. Quasi-cleavage fracture isthought as the main fracture mode. TEM observations expose the formation of dislocation network,slip lines and dislocation pile-ups.
文摘The Frequency-Coded Pulse (FCP) signal has good performance of range and Doppler resolution. This paper first gives the mathematical expression of the ambiguity function for FCP signals, and then presents a coding rule for optimizing FCP signal. The genetic algorithm is presented to solve this kind of problem for optimizing codes. Finally, an example for optimizing calculation is illustrated and the optimized frequency coding results are given with the code length N=64 and N=128 respectively.
文摘Based on 2-dimensional vertically governing equations of salt water intrusion at estuaries, a method is obtained, which can predict quantitatively current velocity and salinity distribution along depth when the intrusion occurs. The volume-controlling method proposed by Patanker and Spalding is used to form the computational pattern and the Power- Law Scheme is used as the diversion pattern of the diffusion term. The comparison between the computational results and the measured ones gives a satisfactory agreement.
文摘The operational performance of a full scale subsurface flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD 5/COD mean ratio of 0 33 at Shatian, Shenzhen City was studied. The constructed wetland system consists of screens, sump, pumping station, and primary settling basin, facultative pond, first stage wetland and secondary stage wetland. The designed treatment capacity is 5000 m 3/d, and the actual influent flow is in the range of <2000 to >10000 m 3/d. Under normal operational conditions, the final effluent quality well met the National Integrated Wastewater Discharge Standard(GB 8978\_1996), with the following parameters(mean values): COD 33 90 mg/L, BOD 5 7.65 mg/L, TSS 7.92 mg/L, TN 9.11 mg/L and TP 0 56 mg/L. Seven species of plants were selected to grow in the wetland: Reed, Sweetcane flower Silvergrass, Great Bulrush, Powdery Thalia and Canna of three colours. The growing season is a whole year round. The seasonal discrepancy could be observed and the plants growing in the wetland are vulnerable to lower temperature in winter. The recycling of the effluent in the first stage of the wetland system is an effective measure to improve the performance of the wetland system. The insufficient DO value in the wetland system not only had significant effect on pollutants removal in the wetland, but also was unfavourable to plant growth. The recycling of effluent to the inlet of wetland system and artificial pond to increase DO value of influent to the wetland is key to operate the subsurface constructed wetland steadily and effectively.
文摘背景与目的:对于肝门部胆管癌(HCCA)而言,R0切除率仍然很低。目前对术前评估、术前胆道引流、门静脉栓塞、手术切除范围、手术方式、血管切除、淋巴结清扫、化疗等问题仍有很多争议。R0切除被认为是HCCA患者获取长期生存的最重要的治疗手段。笔者总结HCCA的治疗体会,并分析不同术式的有效性及近远期疗效。方法:回顾性分析2015年1月—2020年1月行手术治疗的44例HCCA患者的临床资料。结果:44例患者中,Bismuth-Corlette分型I型5例,II型7例,IIIa型8例,IIIb型13例,IV型11例;29例行半肝/扩大半肝+全尾叶切除(联合半肝切除),13例行肝门部/围肝门区+全尾叶切除(围肝门切除),术中包括门静脉部分切除修补2例,门静脉切除重建2例,肝动脉切除重建2例,另2例因肿瘤转移无法切除行T管引流。全组均完成手术,无手术死亡。术后病理结果显示,镜下切缘阴性(R0)切除37例(联合半肝切除组26例,围肝门切除组11例),镜下切缘阳性(R1)切除5例(半肝切除2例、围肝门切除3例)。临床指标分析结果显示,联合半肝切除组的手术时间(240.4 min vs.358.1 min)、术中出血量(705.5 mL vs.809.9 mL)明显少于围肝门切除组,肿瘤标本切缘阳性率(6.9%vs.23.1%)明显低于围肝门切除组(均P<0.05);生存分析结果显示,联合半肝切除组术后与无复发生存期及1年累积生存率明显优于围肝门切除组(均P<0.05)。结论:根治性R0切除是HCCA患者可能获得治愈的唯一方法,与围肝门切除术比较,联合半肝、尾状叶切除的大范围肝切除术,能提高R0切除率,改善无复发生存期及1年生存率。术前精确评估、合理的围手术期治疗、选择个体化的手术方案可提高HCCA的疗效。
