The performance of the immobilized lysozyme and the native lysozyme on enhancing the excess sludge dewaterability was investigated.The results indicated that the specific resistance to filtration(SRF)decreased by 62.8...The performance of the immobilized lysozyme and the native lysozyme on enhancing the excess sludge dewaterability was investigated.The results indicated that the specific resistance to filtration(SRF)decreased by 62.8%for native lysozyme and 53.6%for immobilized lysozyme at the enzyme dosage of 9 mg/g(dry sludge).Correlation analysis was carried out to explore the role of different extracellular polymeric substance(EPS)fractions on excess sludge dewaterability.The results illustrated that the SRF negatively correlated with protein,polysaccharide from soluble EPS(S-EPS)and loosely bound EPS(LB-EPS)and positively correlated with that from tightly bound EPS(TB-EPS).Three-dimensional excitation emission matrix(3D-EEM)fluorescence analysis combined with the scanning electron microscope(SEM)images,revealed that sludge floc structure and microbial cells were destroyed by enzymatic treatment,and that the enzymatic hydrolysis could help to improve the transformation of hydrophilic groups from TB-EPS and the performance of the excess sludge dewatering process.The assessment of hydrolysis using the immobilized enzyme provided a new insight for the safe disposal of the sludge.展开更多
The formation and growth behavior of intermetallic compound(IMC) layers after introducing an electroless Ni-W-P metallization into the Sn-3.0Ag-0.5Cu(SAC305) solder joint during soldering and aging were investigated. ...The formation and growth behavior of intermetallic compound(IMC) layers after introducing an electroless Ni-W-P metallization into the Sn-3.0Ag-0.5Cu(SAC305) solder joint during soldering and aging were investigated. The soldering was performed at 250 ℃ for 10 min, followed by air cooling and aging treatment at 150 ℃ up to 15 days. The results show that the scallop-like Cu_6Sn_5 IMC layer and planar-like Cu_3Sn formed between solder and Cu substrate during soldering and aging. The Ni_3P and(Ni,Cu)_3Sn_4 compounds were formed between electroless Ni-W-P layer and solder, and Cu substrate was not damaged and kept a smooth interface. When the isothermal aging treatment was applied, the total thickness of IMCs which formed at the SAC305/Cu and SAC305/Ni-W-P/Cu interface increased with increasing aging time. Kirkendall voids emerged at the Cu_3Sn and the Ni_3P layers, but the voids emerged at the Ni_3P layer in the form of crack. The amount of Kirkendall voids increased and the crack elongated with increasing aging time. The Cu_6Sn_5 and(Ni,Cu)_3Sn_4grains grew by merging adjacent grains. In the process of growth, the growing interfacial compounds filled the free space, and new columnar dendrite grain of(Ni,Cu)_3Sn_4 constantly generated during aging treatment. After 15 days aging, the Ni-W-P barrier layer was still remained, which indicated that the Ni-W-P layer can be a good barrier layer between the solder alloys and Cu substrate.展开更多
1勘查新发现金矿床地理分布特征据不完全统计(S&P Global Market Intelligence,2024),21世纪以来,全球勘查新发现了167个大型金矿床,其中,有40个分布在非洲(图1),占全球勘查新发现大型金矿床总数量的23.95%,是全球勘查新发现大型金...1勘查新发现金矿床地理分布特征据不完全统计(S&P Global Market Intelligence,2024),21世纪以来,全球勘查新发现了167个大型金矿床,其中,有40个分布在非洲(图1),占全球勘查新发现大型金矿床总数量的23.95%,是全球勘查新发现大型金矿床数量第二多的大洲,仅次于南美洲。从国家分布看,21世纪以来,非洲勘查新发现的40个大型金矿床主要分布在布基纳法索、加纳、科特迪瓦、马里、塞内加尔、几内亚、利比里亚、刚果(金)、纳米比亚、坦桑尼亚、南非、埃塞俄比亚、埃及、苏丹等14国家;其中,布基纳法索是新发现大型金矿床数量最多的国家,有9个;其次为科特迪瓦,有5个;再次为加纳和刚果(金),均有4个;其余10个国家新发现的大型金矿床数量均在3个及以下(表1)。展开更多
The effects of aging time and temperature on the formation and growth behavior of interfacial intermetallic compound(IMC) of Sn-16 Sb/Cu(wt%) solder joints prepared by using dip soldering were investigated. The result...The effects of aging time and temperature on the formation and growth behavior of interfacial intermetallic compound(IMC) of Sn-16 Sb/Cu(wt%) solder joints prepared by using dip soldering were investigated. The results show that the major IMCs between Sn-16 Sb solder and Cu substrate after thermal aging are Cu3 Sn and Cu6 Sn5. The thickness of the interfacial IMC in Sn-16 Sb/Cu is linearly against the square root of aging time, which indicates that the growth of IMC is mainly controlled by diffusion between Cu and Sn atoms. By using linear regression method, the growth rate constants of interfacial IMC layers are 1.254×10^-18, 8.821×10^-18 and 1.22×10^-17 m^2 s^-1 for Sn-16 Sb/Cu joints aged at 120, 150 and 170 ℃, respectively. Besides, the activation energy of the interfacial IMC growth was also calculated to be 68.27 kJ/mol. The IMC grain diameters after aging treatment increase with the increasing aging time, with i e, d = 0.492 t0.106, d = 0.543 t0.143 and d = 0.290 t0.263 for aging temperatures of 120, 150 and 170 ℃, respectively. Besides, by using nanoindentation, the softening of Sn-16 Sb solder was found during aging treatment. Moreover, the U-shape evolution of the values in hardness and Young’s moduli was found in this work.展开更多
The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate...The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate proxy because lithium is a typical lithophile element that is readily adsorbed by clay minerals during weathering and pedogenesis,and thus stratigraphic variations in[Li]leachatecan reflect these processes.We investigated the[Li]leachatevalues of two loess-paleosols profiles(the Luochuan and Weinan sections),on a north-south climatic gradient on the Chinese Loess Plateau.Independent paleoclimate information was provided by measurements of magnetic susceptibility,grain size,Rb/Sr ratios,and clay mineral content.During the last glacial-interglacial period,[Li]leachateincreased from 0.39 to 1.97μg/g at Luochuan and from 0.67 to 2.45μg/g at Weinan,mainly due to increasing pedogenesis.Based on these results we developed a conceptual model to explain the variations in[Li]leachate,Li^(+)within loess layers is mainly derived from dust input and the decomposition of primary minerals,influenced by the East Asian winter monsoon,while in paleosol layers Li is mainly derived from clay mineral adsorption during pedogenic processes,influenced by the East Asian summer monsoon.展开更多
基金“Textile Light”Application Basic Research in China(No.J201503)National Natural Science Foundation of China(No.U1660107)Graduate Innovation Fund of Donghua University,China(No.16D311304)
文摘The performance of the immobilized lysozyme and the native lysozyme on enhancing the excess sludge dewaterability was investigated.The results indicated that the specific resistance to filtration(SRF)decreased by 62.8%for native lysozyme and 53.6%for immobilized lysozyme at the enzyme dosage of 9 mg/g(dry sludge).Correlation analysis was carried out to explore the role of different extracellular polymeric substance(EPS)fractions on excess sludge dewaterability.The results illustrated that the SRF negatively correlated with protein,polysaccharide from soluble EPS(S-EPS)and loosely bound EPS(LB-EPS)and positively correlated with that from tightly bound EPS(TB-EPS).Three-dimensional excitation emission matrix(3D-EEM)fluorescence analysis combined with the scanning electron microscope(SEM)images,revealed that sludge floc structure and microbial cells were destroyed by enzymatic treatment,and that the enzymatic hydrolysis could help to improve the transformation of hydrophilic groups from TB-EPS and the performance of the excess sludge dewatering process.The assessment of hydrolysis using the immobilized enzyme provided a new insight for the safe disposal of the sludge.
基金Funded by National Natural Science Foundation of China(Nos.51465039,51665038)Natural Science Foundation of Jiangxi Province(Nos.20151BAB206041,20161BAB206122)the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201508)
文摘The formation and growth behavior of intermetallic compound(IMC) layers after introducing an electroless Ni-W-P metallization into the Sn-3.0Ag-0.5Cu(SAC305) solder joint during soldering and aging were investigated. The soldering was performed at 250 ℃ for 10 min, followed by air cooling and aging treatment at 150 ℃ up to 15 days. The results show that the scallop-like Cu_6Sn_5 IMC layer and planar-like Cu_3Sn formed between solder and Cu substrate during soldering and aging. The Ni_3P and(Ni,Cu)_3Sn_4 compounds were formed between electroless Ni-W-P layer and solder, and Cu substrate was not damaged and kept a smooth interface. When the isothermal aging treatment was applied, the total thickness of IMCs which formed at the SAC305/Cu and SAC305/Ni-W-P/Cu interface increased with increasing aging time. Kirkendall voids emerged at the Cu_3Sn and the Ni_3P layers, but the voids emerged at the Ni_3P layer in the form of crack. The amount of Kirkendall voids increased and the crack elongated with increasing aging time. The Cu_6Sn_5 and(Ni,Cu)_3Sn_4grains grew by merging adjacent grains. In the process of growth, the growing interfacial compounds filled the free space, and new columnar dendrite grain of(Ni,Cu)_3Sn_4 constantly generated during aging treatment. After 15 days aging, the Ni-W-P barrier layer was still remained, which indicated that the Ni-W-P layer can be a good barrier layer between the solder alloys and Cu substrate.
文摘1勘查新发现金矿床地理分布特征据不完全统计(S&P Global Market Intelligence,2024),21世纪以来,全球勘查新发现了167个大型金矿床,其中,有40个分布在非洲(图1),占全球勘查新发现大型金矿床总数量的23.95%,是全球勘查新发现大型金矿床数量第二多的大洲,仅次于南美洲。从国家分布看,21世纪以来,非洲勘查新发现的40个大型金矿床主要分布在布基纳法索、加纳、科特迪瓦、马里、塞内加尔、几内亚、利比里亚、刚果(金)、纳米比亚、坦桑尼亚、南非、埃塞俄比亚、埃及、苏丹等14国家;其中,布基纳法索是新发现大型金矿床数量最多的国家,有9个;其次为科特迪瓦,有5个;再次为加纳和刚果(金),均有4个;其余10个国家新发现的大型金矿床数量均在3个及以下(表1)。
基金Funded by the National Natural Science Foundation of China(Nos.51465039,51665038,51765040)Natural Science Foundation of Jiangxi Province(Nos.20161BAB206122 and 20171ACB21011)
文摘The effects of aging time and temperature on the formation and growth behavior of interfacial intermetallic compound(IMC) of Sn-16 Sb/Cu(wt%) solder joints prepared by using dip soldering were investigated. The results show that the major IMCs between Sn-16 Sb solder and Cu substrate after thermal aging are Cu3 Sn and Cu6 Sn5. The thickness of the interfacial IMC in Sn-16 Sb/Cu is linearly against the square root of aging time, which indicates that the growth of IMC is mainly controlled by diffusion between Cu and Sn atoms. By using linear regression method, the growth rate constants of interfacial IMC layers are 1.254×10^-18, 8.821×10^-18 and 1.22×10^-17 m^2 s^-1 for Sn-16 Sb/Cu joints aged at 120, 150 and 170 ℃, respectively. Besides, the activation energy of the interfacial IMC growth was also calculated to be 68.27 kJ/mol. The IMC grain diameters after aging treatment increase with the increasing aging time, with i e, d = 0.492 t0.106, d = 0.543 t0.143 and d = 0.290 t0.263 for aging temperatures of 120, 150 and 170 ℃, respectively. Besides, by using nanoindentation, the softening of Sn-16 Sb solder was found during aging treatment. Moreover, the U-shape evolution of the values in hardness and Young’s moduli was found in this work.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42272221,41930863)the Fundamental Research Funds for the Central Universities(Grant No.300102272901)+1 种基金the Foundation of the State Key Laboratory of Loess and Quaternary Geology(Institute of Earth and Environment,CAS)(SKLLQG1905,SKLLQGPY2006)the Second Tibet Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0704,2019QZKK0101)。
文摘The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate proxy because lithium is a typical lithophile element that is readily adsorbed by clay minerals during weathering and pedogenesis,and thus stratigraphic variations in[Li]leachatecan reflect these processes.We investigated the[Li]leachatevalues of two loess-paleosols profiles(the Luochuan and Weinan sections),on a north-south climatic gradient on the Chinese Loess Plateau.Independent paleoclimate information was provided by measurements of magnetic susceptibility,grain size,Rb/Sr ratios,and clay mineral content.During the last glacial-interglacial period,[Li]leachateincreased from 0.39 to 1.97μg/g at Luochuan and from 0.67 to 2.45μg/g at Weinan,mainly due to increasing pedogenesis.Based on these results we developed a conceptual model to explain the variations in[Li]leachate,Li^(+)within loess layers is mainly derived from dust input and the decomposition of primary minerals,influenced by the East Asian winter monsoon,while in paleosol layers Li is mainly derived from clay mineral adsorption during pedogenic processes,influenced by the East Asian summer monsoon.
