Electrodeposition of aluminum from benzene-tetrahydrofuran-Al Cl3-Li Al H4 was studied at room temperature. Galvanostatic electrolysis was used to investigate the effect of various parameters on deposit morphology and...Electrodeposition of aluminum from benzene-tetrahydrofuran-Al Cl3-Li Al H4 was studied at room temperature. Galvanostatic electrolysis was used to investigate the effect of various parameters on deposit morphology and crystal size, including current density, temperature, molar ratio of benzene/tetrahydrofuran and stirring speed. The deposit microstructure was adjusted by changing the parameters, and the optimum operating conditions were determined. Dense, bright and adherent aluminum coatings were obtained over a wide range of current densities(10-25 m A/cm2), molar ratio of benzene and tetrahydrofuran(4:1 to 7:8) and stirring speeds(200-500 r/min). Smaller grain sizes and well-adhered deposits were obtained at lower temperatures. Aluminum-magnesium alloys could potentially be used as hydrogen storage materials. A novel method for Al-Mg deposition was proposed by using pure Mg anodes in the organic solvents system benzene-tetrahydrofuran-Al Cl3-Li Al H4. XRD shows that the aluminum-magnesium alloys are mainly Al3Mg2 and Al12Mg17.展开更多
The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Nort...The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Northern Viet Nam. Among the three climate change scenarios B 1, B2, and A2, representing low, medium, and high levels of greenhouse gas emission, respectively were set up for Viet Nam, the B2 scenario was selected for this study. Two land use scenarios （S1-2030 and $2-2050） were formulated combination with climate change in WSAT simulation. In B2 climate change scenario, mean temperature increases 0.7℃（2030） and 1.3 ℃ （2050）; annual rainfall increases 2.1% （2030） and 3.80% （2050） respect to baseline scenario. The results show that the stream discharge is likely to increase in the future during the wet season with increasing threats of sedimentation.展开更多
Sediment carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. To clarify the late Quaternary strata and carbon burial records in YeUow Riv...Sediment carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. To clarify the late Quaternary strata and carbon burial records in YeUow River delta （YRD）, detailed analysis of benthic foraminifera, total carbon （TC）, organic carbon （Corg）, sedimentary characteristics and moisture contents of sediments, was performed on core ZK3, 30.3 m in length and obtained from YRD in 2007. Eight depositional units （designated U1-U8 in ascending order） were identified. A comprehensive analysis method of historical geography and sedimentary geology was used to de- termine the precise depositional ages of the modem Yellow River delta （MYRD）, from which pre-MYRD ages were deduced. The results indicates that the maximum burial rates of TC, inorganic carbon （IC） and Corg occurred in the delta front （U5）, and the mini- mum in the shallow sea （U3）. Remarkable high sedimentation rates in the MYRD are responsible for burial efficiency of carbon, with an average rate of Corg burial reaching 2087±251 g（m2yr）-1, and that of IC reaching 13741±808g（m2yr）-1, which are much higher than those of other regions with high contents of Corg. Therefore, YRD has a significant burial efficiency for carbon sequestration.展开更多
Room-temperature ferromagnetism with a Curie temperature higher than 380 K was studied in GaN: Mn thin films grown by metal-organic chemical vapor deposition. By etching artificial microstructures on the GaN: Mn layer...Room-temperature ferromagnetism with a Curie temperature higher than 380 K was studied in GaN: Mn thin films grown by metal-organic chemical vapor deposition. By etching artificial microstructures on the GaN: Mn layer,strong magnetic responses were observed in the magnetic force microscopy (MFM) measurement,which revealed that the films were independent of dopant particles and clusters. Numerical simulation on the data of atomic force microscope (AFM) and MFM measurements covering the whole microstructure validated the formation of long range magnetic order. This result excluded a variety of controversial origins of room-temperature ferromagnetism in the GaN: Mn and gave a strong evidence of our GaN: Mn as the intrinsic diluted magnetic semiconductor (DMS). The forwarded method for accurate characterization of long range magnetic order could be applied to a wide range of DMS and diluted magnetic oxide (DMO) systems.展开更多
Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously dist...Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously distributed at the a-C/Si interface. Both types of Co2-C98/Si samples had the positive bias-voltage-dependent magnetoresistance (MR) at 300 K, and all MRs had saturated behavior. The study on the electrotransport properties indicated that the MR appeared in the diffusion current region, and the mechanism of MR was proposed to be that the applied magnetic field and local random magnetic field caused by the superparamagnetic Co particles modulate the ratio of singlet and triplet spin states, resulting in the MR effect. In addition, the very different physical and structural properties of all samples revealed that Co played a crucial role in the room-temperature positive MR of a-C:Co/Si system.展开更多
In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal anne...In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal annealing(RTA).The characterizations show that the epitaxial SiGe thin films are single-crystalline with uniform tensile strain and then become polycrystalline after the ion implantation and following RTA.The magnetization measurements indicate that the annealed thin films exhibit Mn concentration-dependent ferromagnetism up to 309 K and the X-ray magnetic circular dichroism characterizations reveal the spin and orbital magnetic moments from the substitutional Mn element.To minimize the influence of anomalous Hall effect,magneto-transport measurements at a high magnetic field up to 31 T at 300 K are performed to obtain the hole mobility,which reaches a record-high value of~1230 cm^(2)V^(-1)s^(-1),owing to the crystalline quality and tensile strain-induced energy band modulation of the samples.The first demonstration of Mn-doped SiGe thin films with roomtemperature ferromagnetism and high carrier mobility may pave the way for practical semiconductor spintronic applications.展开更多
基金Projects(51101104,51372156)supported by the National Natural Science Foundation of ChinaProject(LJQ2015074)supported by the Program for Liaoning Excellent Talents in University,China
文摘Electrodeposition of aluminum from benzene-tetrahydrofuran-Al Cl3-Li Al H4 was studied at room temperature. Galvanostatic electrolysis was used to investigate the effect of various parameters on deposit morphology and crystal size, including current density, temperature, molar ratio of benzene/tetrahydrofuran and stirring speed. The deposit microstructure was adjusted by changing the parameters, and the optimum operating conditions were determined. Dense, bright and adherent aluminum coatings were obtained over a wide range of current densities(10-25 m A/cm2), molar ratio of benzene and tetrahydrofuran(4:1 to 7:8) and stirring speeds(200-500 r/min). Smaller grain sizes and well-adhered deposits were obtained at lower temperatures. Aluminum-magnesium alloys could potentially be used as hydrogen storage materials. A novel method for Al-Mg deposition was proposed by using pure Mg anodes in the organic solvents system benzene-tetrahydrofuran-Al Cl3-Li Al H4. XRD shows that the aluminum-magnesium alloys are mainly Al3Mg2 and Al12Mg17.
文摘The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Northern Viet Nam. Among the three climate change scenarios B 1, B2, and A2, representing low, medium, and high levels of greenhouse gas emission, respectively were set up for Viet Nam, the B2 scenario was selected for this study. Two land use scenarios （S1-2030 and $2-2050） were formulated combination with climate change in WSAT simulation. In B2 climate change scenario, mean temperature increases 0.7℃（2030） and 1.3 ℃ （2050）; annual rainfall increases 2.1% （2030） and 3.80% （2050） respect to baseline scenario. The results show that the stream discharge is likely to increase in the future during the wet season with increasing threats of sedimentation.
基金funded by the National Natural Science Foundation of China (Grant Nos. 41406082, ZR2014DQ010, 40872167 and 41240022)Governmental Public Research Funds of China (Grant Nos. 201111023, 1212010611402 and GZH201200503)
文摘Sediment carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. To clarify the late Quaternary strata and carbon burial records in YeUow River delta （YRD）, detailed analysis of benthic foraminifera, total carbon （TC）, organic carbon （Corg）, sedimentary characteristics and moisture contents of sediments, was performed on core ZK3, 30.3 m in length and obtained from YRD in 2007. Eight depositional units （designated U1-U8 in ascending order） were identified. A comprehensive analysis method of historical geography and sedimentary geology was used to de- termine the precise depositional ages of the modem Yellow River delta （MYRD）, from which pre-MYRD ages were deduced. The results indicates that the maximum burial rates of TC, inorganic carbon （IC） and Corg occurred in the delta front （U5）, and the mini- mum in the shallow sea （U3）. Remarkable high sedimentation rates in the MYRD are responsible for burial efficiency of carbon, with an average rate of Corg burial reaching 2087±251 g（m2yr）-1, and that of IC reaching 13741±808g（m2yr）-1, which are much higher than those of other regions with high contents of Corg. Therefore, YRD has a significant burial efficiency for carbon sequestration.
基金supported by the National Natural Science Foundation of China (Grant Nos.60577030,60776041,60876035)the National Key Basic Research Special Foundation of China (Grant Nos.TG2007CB307004,2006CB921607)
文摘Room-temperature ferromagnetism with a Curie temperature higher than 380 K was studied in GaN: Mn thin films grown by metal-organic chemical vapor deposition. By etching artificial microstructures on the GaN: Mn layer,strong magnetic responses were observed in the magnetic force microscopy (MFM) measurement,which revealed that the films were independent of dopant particles and clusters. Numerical simulation on the data of atomic force microscope (AFM) and MFM measurements covering the whole microstructure validated the formation of long range magnetic order. This result excluded a variety of controversial origins of room-temperature ferromagnetism in the GaN: Mn and gave a strong evidence of our GaN: Mn as the intrinsic diluted magnetic semiconductor (DMS). The forwarded method for accurate characterization of long range magnetic order could be applied to a wide range of DMS and diluted magnetic oxide (DMO) systems.
基金support given by the National Natural Science Foundation of China (Grant Nos. U0734001 and 50772054)the Ministry of Science and Technology of China (Grant Nos. 2008CB617601 and 2009CB929202)
文摘Three types of a-C:Co/Si samples were fabricated using the pulsed laser deposition: Co2-C98/8i with Co dispersed in the a-C film, Co2-C98/Si with Co segregated at the interface, and a-C/Co/Si with Co continuously distributed at the a-C/Si interface. Both types of Co2-C98/Si samples had the positive bias-voltage-dependent magnetoresistance (MR) at 300 K, and all MRs had saturated behavior. The study on the electrotransport properties indicated that the MR appeared in the diffusion current region, and the mechanism of MR was proposed to be that the applied magnetic field and local random magnetic field caused by the superparamagnetic Co particles modulate the ratio of singlet and triplet spin states, resulting in the MR effect. In addition, the very different physical and structural properties of all samples revealed that Co played a crucial role in the room-temperature positive MR of a-C:Co/Si system.
基金supported by the National Key Research and Development Program of China(2017YFB0405702)the National Natural Science Foundation of China(52172272)。
文摘In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal annealing(RTA).The characterizations show that the epitaxial SiGe thin films are single-crystalline with uniform tensile strain and then become polycrystalline after the ion implantation and following RTA.The magnetization measurements indicate that the annealed thin films exhibit Mn concentration-dependent ferromagnetism up to 309 K and the X-ray magnetic circular dichroism characterizations reveal the spin and orbital magnetic moments from the substitutional Mn element.To minimize the influence of anomalous Hall effect,magneto-transport measurements at a high magnetic field up to 31 T at 300 K are performed to obtain the hole mobility,which reaches a record-high value of~1230 cm^(2)V^(-1)s^(-1),owing to the crystalline quality and tensile strain-induced energy band modulation of the samples.The first demonstration of Mn-doped SiGe thin films with roomtemperature ferromagnetism and high carrier mobility may pave the way for practical semiconductor spintronic applications.
