Search

Doppler radio tracking data from Tianwen-1, China’s first Mars mission, could contribute to a better estimate of the gravity field of Phobos. In this study, we show that a determination up to degree and order 3 is feasible by considering five additional flybys of Phobos by the Tianwen-1 spacecraft, in addition to the previous flybys already done by the Mars Express spacecraft, and probably degree and order 5 is within reach. Three cases of mass repartition are considered: (i) a homogeneous case, (ii) a core-dominated Phobos, and (iii) a mantle-dominated Phobos. The case of a mantle-dominated Phobos is the easiest to detect, followed by a homogeneous Phobos, and finally by a core-dominated Phobos. We also discuss implications about the modelling of the internal structure of Phobos.

In view of the problems of low solar energy utilization efficiency, drying efficiency to be improved and sludge adhesion in the process of solar drying sludge, the research was carried out on the heat collection effect of solar collectors, sludge drying characteristics and sludge drying process, as well as the influence of sludge drying process parameters on the sludge drying rate such as hot air temperature, solar radiation intensity and air substitution,. on the self-built industrial simulation test bench. The results show that: the maximum temperature difference between the inside and the outdoor environment of the solar collectors is 36°C, when the outdoor environment temperature of the developed solar collectors is 13-26°C; the optimum process parameters of sludge drying rate under the experimental conditions that the moisture content of wet sludge is 82.7%, are as follows: the temperature of hot air is 43°C, the maximum solar radiation intensity (about 12:00), the optimal flow rate of air is controlled at 1.2m/s, the thickness of the material layer is 3cm, the large contact between air and materials improves the problem of sludge adhesion. All which provide a theoretical basis for the implementation on the industrialization of solar drying sludge.

In industrial processing, a centrifugal pump is mostly used reversely as the micro-hydraulic turbine for its lower cost. In some application situation, the working fluid will contain a part of gas which will reduce the efficiency, stability, and the power output of the machine. Due to the lower efficiency and stability of the pump as turbine (PAT) working with liquid flow, the working characteristic will deteriorate furtherly when the working fluid contains gas. Therefore, a micro-hydraulic turbine based on Francis turbine model is designed and proposed to except to obtain good performance under two-phase flow working condition. In this study, the three-dimensional transient two-phase flow model which adapts the k-ω model as turbulence model and Eulerian-Eulerian model as two-phase flow model with the commercial code ANSYS-CFX was established and solved to study the two-phase flow characteristics of the micro-hydraulic turbine with fixed guide vane openings under different gas volume fraction (GVF). The numerical simulation results show that the power, efficiency and torque of the turbine decrease with GVF. Due to the expansion of the gas in working fluid, the velocity of fluid increases with the gas, which leads to the bigger lower pressure area near the exit of the impeller. The vortex at the back of the blade is also intensified when the gas fraction increase. When the GVF is larger than 10%, the gas distribution is inhomogeneous, and most of them gather at the back side of the blade near the exit of the impeller where the GVF can reach 90%. The efficiency of the micro-hydraulic turbine is about 60% when the GVF is 20%, which needs to be improved in the future.

To investigate the liver pathological characteristics and the clearance rate of hepatitis B surface antigen (HBsAg) with antiviral treatment for 1 to 7 years old children with heptitis B e antigen(HBeAg)-negative chronic hepatitis B.A total of 49 cases with HBeAg-negative chronic hepatitis B were treated with interferon (IFN) or IFN treatment for 6 months added with lamivudine, and were followed up for at least 6 months.Retrospective analysis was performed on the liver pathological characteristics, the efficacy of antivirus treatment and its influencing factors of the HBsAg clearance rate in the cases from June 2006 to December 2013 in the 302 Hospital of People's Liberation Army.The χ(2) test was used to compare the rates.(1)The median age of cases was 3 years old(1-7 years old), 38 children were male(78%). Cases in the age group 1-2,2 -3,3 -4,4-5,5-6 and6-7 were 7, 8, 14, 6, 6 and 8 respectively. HBsAg was 100% positive in mother of the cases. (2)There were 7 children whose pre-treatment alanine aminotransferase (ALT) were ≤80 U/L and pre-treatment ALT200 U/L in 25 children. There were 24 children whose pre-treatment HBVDNA ≥1×10(7) U/ml. Genetype analysis was detected in 43 children, 3 children were B genotype, 38 were C genotype, 2 were B and C genotype. (3)Liver biopsy was performed in all children. The degree of liver inflammation ≥2 was seen in 48 (98%) children.Severe liver fibrosis and cirrhosis were found in 21(43%) children. (4)In the age group 1-2,2-3,3-4,4-5,5-6 and6-7 years old , the clearance of HBsAg was 5, 6, 2, 1, 0 and 0 respectively. The HBsAg clearance rate between 1-3 years old group and 3-7 years old group has significant difference ((73%(11/15) vs. 9%(3/34), χ(2)=18.180, P=0.000). (5)The clearance of HBsAg in male group was 11, but 3 in female group.It showed no significant difference between two groups (χ(2)=0.073, P=0.787). (6) The clearance rate of HBsAg were 0, 24%(4/17) and 40%(10/25) in the groups of pre-treatment ALT ≤80 U/L, 80ALT≤200 U/L and ALT200 U/L, respectively. There were no significant difference between the groups of ALT≤200 U/L and ALT200 U/L(χ(2)=2.223, P=0.136). In the groups with pre-treatment HBV DNA1×10(7)U/ml and HBV DNA≥1×10(7)U/ml, the clearance rate of HBsAg was 28%(7/25) and 29%(7/24). There were no significant elifference between two groups(χ(2)=0.008, P=0.928). (7)The clearance rate of HBsAg was 33%(7/21) in children with severe liver fibrosis and cirrhosis, while 25%(7/28) in children who had no severe liver fibrosis and cirrhosis.There were no significant difference between two groups(χ(2)=0.408, P=0.523).There are obvious liver injuries and severe liver fibrosis in 1-7 years old children with HBeAg-negative chronic hepatitis B. The HBsAg clearance rate in the children with antiviral treatment correlated with age, among those who received antiviral treatment before 3 years old, the HBsAg clearance rate is relatively higher.

Using first-principles calculation we investigated the structural, electronic and elastic properties of paramagnetic CaFeAs2. Our results indicated that the density of states (DOS) was dominated predominantly by Fe-3[Formula: see text] states at Fermi levels, and stronger hybridization exists between As1 and As1 atoms. Three hole pockets are formed at [Formula: see text] and Z points, and two electronic pockets are formed at A and E points. The Dirac cone-like bands appear near B and D points. For the first time we calculated the elastic properties and found that CaFeAs2 is a mechanically stable and moderately hard material, it has elastic anisotropy and brittleness, which agrees well with the bonding picture and the calculation of Debye temperature ([Formula: see text]).

Mechanical and electronic properties of Cu2Sb-type compounds MFeAs (M = Cu, Li, and Na) have been studied by the first-principles calculations. The main trends in structure parameters, mechanical parameters, electronic bands, and densities of states (DOS) for MFeAs are analyzed according to the variable cation M sites. Our results show that the lattice constants increase, while the bulk modulus, shear modulus, and Young's modulus decrease with the increasing radii of M sites in the sequence CuFeAs → LiFeAs → NaFeAs. Mulliken overlap population indicates that different M atoms in MFeAs (M = Cu, Li, and Na) would influence the bond nature of Fe-As, which may induce the superconductivity. The disappearance of the hole-pockets affects the superconductivity in CuFeAs. Although the value of the DOSs N(EF) at the Fermi level grows with decreasing radii of M sites, it is not the only factor influencing the superconductivity. Due to the repulsive interaction between Cu-3d and Fe-3d states in CuFeAs phase, it would...