The present investigation showed that the additions of Ca to the alloy AZ91 were mainly dissolved into the Mg17Al12 phase and increased its melting point and thermal stability, which would have great effects on the hi...The present investigation showed that the additions of Ca to the alloy AZ91 were mainly dissolved into the Mg17Al12 phase and increased its melting point and thermal stability, which would have great effects on the high-temperature properties of AZ91 alloy. The empirical electron theory (EET) of solid and molecules was used to calculate the valence electron structures (VES) of Mg17Al12 intermetallic compound with and without Ca addition. The results showed that Ca dissolving in Mg17Al12 phase increased the strength of bonds that control the thermal stability of Mg17Al12 phase. Additions of Ca also made the distribution of the valence electrons on the dominant bond network more uniform in the whole unit cell of Mg17Al12. The theoretical conclusions well account for the experimental results.展开更多
Based on the empirical electron theory of solids and molecules of S. H. Yu, this paper proposes (i) the calculating model of valence electron structures in L_2~'-type substitutional and interstitial complex solid ...Based on the empirical electron theory of solids and molecules of S. H. Yu, this paper proposes (i) the calculating model of valence electron structures in L_2~'-type substitutional and interstitial complex solid solutions; (ii) the bond length difference analysis (BLD) method of unknown bond length structure solid solutions; (iii) the treatment of uncertainty of BLD analysis solution.展开更多
The valence electron structure (VES) of RuB2 and OsB2 were calculated by the empirical electron theory (EET) of solids and molecules and compared with the results derived from the first-principles calculations. The di...The valence electron structure (VES) of RuB2 and OsB2 were calculated by the empirical electron theory (EET) of solids and molecules and compared with the results derived from the first-principles calculations. The distributions of covalent electrons in different bonds indicate that B-B and B-Me have remarkably covalent bonding characters. Lattice electrons cruising around Me-Me layers are found to have great influences on electronic conductivity and high temperature plasticity. The ultra-high values of elastic constant Cn in the two compounds originate from close-packed covalent bonding along the c axis. Uneven bond strengths and distributions of covalent bonds, especially for B-Afe bonds, yield significant anisotropy. Low ratios of lattice electrons to covalent electrons suggest the intrinsic embrittlement in crystals. The fact that the calculated cohesive energies well agree with experimental results demonstrates the good suitability of the EET calculations in estimating cohesive energy for transition-metal borides.展开更多
Storage modulus and loss modulus is the main performance index of visco-elastic properties.In this paper the storage modulus and loss modulus of a new diverting acid and their influencing factors were systematically i...Storage modulus and loss modulus is the main performance index of visco-elastic properties.In this paper the storage modulus and loss modulus of a new diverting acid and their influencing factors were systematically investigated.Besides,the constitutive equations of the diverting acid at different temperatures were elicited from shearing experiments,which show that the visco-elastic surfactant(VES)acid system is a non-Newtonian power law fluid at low temperature and a Newtonian fluid at high temperature.The storage modulus and loss modulus at different temperatures,pH,and VES content in the acid are critical for the design of acid stimulation for oil well,especially when the VES acid is used in this field only on trial and the basic data are in urgent needed for the design and construction of the acidification stimulation.展开更多
Surface electrical resistivity has been used as a tool in the detection of groundwater contamination. In this work, five geoelectric soundings with two at waste dumpsites have been carried out in Uyo, Southwestern Nig...Surface electrical resistivity has been used as a tool in the detection of groundwater contamination. In this work, five geoelectric soundings with two at waste dumpsites have been carried out in Uyo, Southwestern Nigeria to map the gross layered structure of the refuse as well as the extent of groundwater contamination. The geology of the area (Benin Formation) mainly consists of fine-medium-coarse grained sands. The data of five Schlumberger Vertical Electrical Soundings (VES), with a maximum of AB/2=500 m, were analyzed using Hemkler computer program. In general, there exists a common feature in the resistivity variation pattern of high-low-high-low-high in the area. The result shows a wide range of resistivity variation ranging from 2.0 to 60700 ?m. Based on the survey results, the resistivity values less than 75 ?m shows contamination due to waste at Eka street and Udo street. Also, the high resistivity value at mechanic village (60700 ?m) may be related to the waste oil deposit due to the automobile repair activities. A comparison of the resistivity values and the curve types at the dumpsites (Eka street and Udo street) and other locations show that the two dumpsites have an H curve type indicating contaminated zones, while other locations have a K curve type indicating non contaminated zones. Hydrochemical analysis of groundwater samples collected in the area was also carried out for some physico-chemical parameters. The results produced higher concentration of conductivity, total dissolved solids and chloride values for water collected at close locations to dumpsites than those far away from the dumpsites: an evidence for a quantitative assessment of groundwater contamination.展开更多
A new method of adaptable rendering for interaction in Virtual Environment(VE) through different visual acuity equations is proposed. An acuity factor equation of luminance vision is first given. Secondly, five equati...A new method of adaptable rendering for interaction in Virtual Environment(VE) through different visual acuity equations is proposed. An acuity factor equation of luminance vision is first given. Secondly, five equations which calculate the visual acuity through visual acuity factors are presented, and adaptive rendering strategy based on different visual acuity equations is given. The VE system may select one of them on the basis of the host’s load, hereby select LOD for each model which would be rendered. A coarser LOD is selected where the visual acuity is lower, and a better LOD is used where it is higher. This method is tested through experiments and the experimental results show that it is effective.展开更多
维生素E琥珀酸酯(vitamin E succinate,VES)是天然维生素E衍生物,具有抑制不同肿瘤细胞生长、增殖和选择性诱导肿瘤细胞凋亡的作用。VES能够有效的抑制乳腺癌细胞增殖作用,其作用机制主要与Fas蛋白及TGF-β1蛋白水平上调有关。VES联合...维生素E琥珀酸酯(vitamin E succinate,VES)是天然维生素E衍生物,具有抑制不同肿瘤细胞生长、增殖和选择性诱导肿瘤细胞凋亡的作用。VES能够有效的抑制乳腺癌细胞增殖作用,其作用机制主要与Fas蛋白及TGF-β1蛋白水平上调有关。VES联合化疗药物后能够使乳腺癌细胞表面的Fas表达上调,显著的抑制细胞增殖,诱导细胞凋亡。VES与他莫西酚(Tamoxifen,TAM)具有协同作用,联合用药后对乳腺癌细胞的凋亡诱导作用增强。因此,这些机制的研究发现可以评价VES的临床应用价值,对肿瘤学的发展及抗肿瘤药物的开发起着重要作用。展开更多
Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using re...Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using resistivity and hydrogeological approaches.Static water level measurements of hand dug wells were used to determine the groundwater flow direction for the area which coincides with the North East-South West joint direction.Constant rate pumping test was adopted for the research and 10 boreholes were pumped.The weathered/fractured basement range from 7.5 m to 56.7 m.The transmissivity values in the area ranged from 0.35 m^(2)/d to 3.63 m^(2)/d while the hydraulic conductivity range from 0.045 m/d to 0.18 m/d.The Vertical Electrical Soundings(VES)were carried out on the area.The geoelectric sections revealed four to five layers and the longitudinal conductance varied from 0.11Ω^(-1)to 0.37Ω^(-1).The results of the investigation characterized the groundwater potential in the study area into low and moderate while the aquifer protective capacity into weak and moderate zones.The efficacy of resistivity and pumping test data in quantifying aquifer properties has been established in this study.The findings of this study shed light on the properties of ground water and aquifer protective capacity in the area,hence assist in the effective future groundwater resources exploitation.展开更多
A geoelectric survey employing the vertical electrical sounding (VES) was carried out in parts of Onicha-Ugbo in Aniocha North Local Government Area of Delta State using Abem Terrameter SAS 300C together with SAS 2000...A geoelectric survey employing the vertical electrical sounding (VES) was carried out in parts of Onicha-Ugbo in Aniocha North Local Government Area of Delta State using Abem Terrameter SAS 300C together with SAS 2000 booster. The study was carried out with the aim of delineating the subsurface geologic sequence present in the study area, determining their geoelectrical parameters (layer thicknesses and resistivities), and delineating the structural and geomorphological features present beneath the subsurface. The results of the survey suggest that the subsurface comprises of 5 - ?6 layers and that clay and silt content varies vertically and horizontally, thus influencing the apparent resistivity of the area. The geoelectric section developed shows that the subsurface units are dominantly sandy underlying loamy sandy topsoil which is relatively dry. The depth to water table from the sites is above 150 m and suggests that groundwater exploration is encouraging.展开更多
文摘The present investigation showed that the additions of Ca to the alloy AZ91 were mainly dissolved into the Mg17Al12 phase and increased its melting point and thermal stability, which would have great effects on the high-temperature properties of AZ91 alloy. The empirical electron theory (EET) of solid and molecules was used to calculate the valence electron structures (VES) of Mg17Al12 intermetallic compound with and without Ca addition. The results showed that Ca dissolving in Mg17Al12 phase increased the strength of bonds that control the thermal stability of Mg17Al12 phase. Additions of Ca also made the distribution of the valence electrons on the dominant bond network more uniform in the whole unit cell of Mg17Al12. The theoretical conclusions well account for the experimental results.
基金Project supported by the National Natural Science Foundation of China.
文摘Based on the empirical electron theory of solids and molecules of S. H. Yu, this paper proposes (i) the calculating model of valence electron structures in L_2~'-type substitutional and interstitial complex solid solutions; (ii) the bond length difference analysis (BLD) method of unknown bond length structure solid solutions; (iii) the treatment of uncertainty of BLD analysis solution.
文摘The valence electron structure (VES) of RuB2 and OsB2 were calculated by the empirical electron theory (EET) of solids and molecules and compared with the results derived from the first-principles calculations. The distributions of covalent electrons in different bonds indicate that B-B and B-Me have remarkably covalent bonding characters. Lattice electrons cruising around Me-Me layers are found to have great influences on electronic conductivity and high temperature plasticity. The ultra-high values of elastic constant Cn in the two compounds originate from close-packed covalent bonding along the c axis. Uneven bond strengths and distributions of covalent bonds, especially for B-Afe bonds, yield significant anisotropy. Low ratios of lattice electrons to covalent electrons suggest the intrinsic embrittlement in crystals. The fact that the calculated cohesive energies well agree with experimental results demonstrates the good suitability of the EET calculations in estimating cohesive energy for transition-metal borides.
基金Supported by the Acidification for Heterogeneous Carbonate Reservoirs Program of Petro China Company Limited
文摘Storage modulus and loss modulus is the main performance index of visco-elastic properties.In this paper the storage modulus and loss modulus of a new diverting acid and their influencing factors were systematically investigated.Besides,the constitutive equations of the diverting acid at different temperatures were elicited from shearing experiments,which show that the visco-elastic surfactant(VES)acid system is a non-Newtonian power law fluid at low temperature and a Newtonian fluid at high temperature.The storage modulus and loss modulus at different temperatures,pH,and VES content in the acid are critical for the design of acid stimulation for oil well,especially when the VES acid is used in this field only on trial and the basic data are in urgent needed for the design and construction of the acidification stimulation.
文摘Surface electrical resistivity has been used as a tool in the detection of groundwater contamination. In this work, five geoelectric soundings with two at waste dumpsites have been carried out in Uyo, Southwestern Nigeria to map the gross layered structure of the refuse as well as the extent of groundwater contamination. The geology of the area (Benin Formation) mainly consists of fine-medium-coarse grained sands. The data of five Schlumberger Vertical Electrical Soundings (VES), with a maximum of AB/2=500 m, were analyzed using Hemkler computer program. In general, there exists a common feature in the resistivity variation pattern of high-low-high-low-high in the area. The result shows a wide range of resistivity variation ranging from 2.0 to 60700 ?m. Based on the survey results, the resistivity values less than 75 ?m shows contamination due to waste at Eka street and Udo street. Also, the high resistivity value at mechanic village (60700 ?m) may be related to the waste oil deposit due to the automobile repair activities. A comparison of the resistivity values and the curve types at the dumpsites (Eka street and Udo street) and other locations show that the two dumpsites have an H curve type indicating contaminated zones, while other locations have a K curve type indicating non contaminated zones. Hydrochemical analysis of groundwater samples collected in the area was also carried out for some physico-chemical parameters. The results produced higher concentration of conductivity, total dissolved solids and chloride values for water collected at close locations to dumpsites than those far away from the dumpsites: an evidence for a quantitative assessment of groundwater contamination.
文摘A new method of adaptable rendering for interaction in Virtual Environment(VE) through different visual acuity equations is proposed. An acuity factor equation of luminance vision is first given. Secondly, five equations which calculate the visual acuity through visual acuity factors are presented, and adaptive rendering strategy based on different visual acuity equations is given. The VE system may select one of them on the basis of the host’s load, hereby select LOD for each model which would be rendered. A coarser LOD is selected where the visual acuity is lower, and a better LOD is used where it is higher. This method is tested through experiments and the experimental results show that it is effective.
文摘维生素E琥珀酸酯(vitamin E succinate,VES)是天然维生素E衍生物,具有抑制不同肿瘤细胞生长、增殖和选择性诱导肿瘤细胞凋亡的作用。VES能够有效的抑制乳腺癌细胞增殖作用,其作用机制主要与Fas蛋白及TGF-β1蛋白水平上调有关。VES联合化疗药物后能够使乳腺癌细胞表面的Fas表达上调,显著的抑制细胞增殖,诱导细胞凋亡。VES与他莫西酚(Tamoxifen,TAM)具有协同作用,联合用药后对乳腺癌细胞的凋亡诱导作用增强。因此,这些机制的研究发现可以评价VES的临床应用价值,对肿瘤学的发展及抗肿瘤药物的开发起着重要作用。
基金Authors wish to acknowledge the African Water Resources Mobility Network(A WaRMN)for supporting this research through the Intra-African Academic Mobility Programme No.2019-1973/004-001,which was funded by the European Union.
文摘Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using resistivity and hydrogeological approaches.Static water level measurements of hand dug wells were used to determine the groundwater flow direction for the area which coincides with the North East-South West joint direction.Constant rate pumping test was adopted for the research and 10 boreholes were pumped.The weathered/fractured basement range from 7.5 m to 56.7 m.The transmissivity values in the area ranged from 0.35 m^(2)/d to 3.63 m^(2)/d while the hydraulic conductivity range from 0.045 m/d to 0.18 m/d.The Vertical Electrical Soundings(VES)were carried out on the area.The geoelectric sections revealed four to five layers and the longitudinal conductance varied from 0.11Ω^(-1)to 0.37Ω^(-1).The results of the investigation characterized the groundwater potential in the study area into low and moderate while the aquifer protective capacity into weak and moderate zones.The efficacy of resistivity and pumping test data in quantifying aquifer properties has been established in this study.The findings of this study shed light on the properties of ground water and aquifer protective capacity in the area,hence assist in the effective future groundwater resources exploitation.
文摘A geoelectric survey employing the vertical electrical sounding (VES) was carried out in parts of Onicha-Ugbo in Aniocha North Local Government Area of Delta State using Abem Terrameter SAS 300C together with SAS 2000 booster. The study was carried out with the aim of delineating the subsurface geologic sequence present in the study area, determining their geoelectrical parameters (layer thicknesses and resistivities), and delineating the structural and geomorphological features present beneath the subsurface. The results of the survey suggest that the subsurface comprises of 5 - ?6 layers and that clay and silt content varies vertically and horizontally, thus influencing the apparent resistivity of the area. The geoelectric section developed shows that the subsurface units are dominantly sandy underlying loamy sandy topsoil which is relatively dry. The depth to water table from the sites is above 150 m and suggests that groundwater exploration is encouraging.
