BackgroundWith the increase in revision total hip arthroplasty (THA) cases, understanding its causes is essential for a surgeons' clinical decision-making. Studies have reported on revision THA epidemiology in developed countries; however, its epidemiology in China remains unclear. We reviewed revision THA causes in a tertiary center in China. Methods We retrospectively identified 1,353 revision THAs at our institution from January 1999 to December 2018 (20 years). The causes for revision THA were compared among patients who were grouped based on the time of revision surgery, age at revision, and number of revisions, using the Student's t -test. Results Aseptic loosening (826 hips, 61.0%) and infection (151 hips, 11.2%) were the most common reasons for revision THA. Compared with the number of cases from January 1999 to December 2008, the number of cases from January 2009 to December 2018 increased 2.4-fold; the proportion of revisions due to aseptic loosening, periprosthetic fracture, instability, and osteolysis increased, and infection rate decreased. The infection rate was higher among patients aged over 60 years, whereas the incidence rate of aseptic loosening, periprosthetic fracture, and instability was higher among those aged 60 years or less. Infections (52.8%) were more common than aseptic loosening (37.4%) in second or subsequent revisions. Conclusion Aseptic loosening and infection remain the most common causes of revision THAs at our center. Although the proportion of infections has decreased in the recent decade, a national database is necessary for a more comprehensive understanding of the causes of revision THAs in China. This work provides an understanding and comparison of the causes of revision THA in an orthopedic center among the Chinese population. This may reveal a potential change in revision THAs causes in the future, reminding surgeons to find a proper way to treat them.

Linezolid (LZD) is one of the first commercially available synthetic oxazolidinone antibiotics and is widely used for the treatment of multidrug-resistant Gram-positive bacterial infection. LZD was found to have five polymorphic forms. The most stable and commercialized polymorphs are known as forms II and IV. Trace content of form II in LZD form IV will cause to transition LZD form IV to II rapidly. Powder X-ray diffraction (PXRD) methods were evaluated for the determination of the polymorphic content of the drug substance and drug product. The estimated limit of detection values of the single peak method for LZD polymorph form II in drug substance and tablet formulation were 0.4 and 0.6%, respectively, while the limit of detection value of Rietveld Refinement (full-profile fitting) evaluated LZD polymorph form II in drug substance was 0.2%. The results clearly show that levels <1 wt.% (in active pharmaceutical ingredients) and 2 wt.% (in tablets) LZD form II in form IV can be detected and quantified by PXRD. Validation of the analytical method proved that the method is repeatable, sensitive, and accurate.

Vortioxetine, C18H22N2S, (1), systematic name 1-{2-[(2,4-dimethylphenyl)sulfanyl]phenyl}piperazine, a new drug used to treat patients with major depressive disorder, has been crystallized as the free base and its methanol monosolvate, C18H22N2S·CH3OH, (2). In both structures, the vortioxetine molecules have similar conformations: in (1), the dihedral angle between the aromatic rings is 80.04 (16)° and in (2) it is 84.94 (13)°. The C—S—C bond angle in (1) is 102.76 (14)° and the corresponding angle in (2) is 103.41 (11)°. The piperazine ring adopts a chair conformation with the exocyclic N—C bond in a pseudo-equatorial orientation in both structures. No directional interactions beyond normal van der Waals contacts could be identified in the crystal of (1), whereas in (2), the vortioxetine and methanol molecules are linked by N—H...O and O—H...N hydrogen bonds, generating [001] chains.

In the title compound, [systematic name: 9-fluoro-2,3-dihydro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-7H-pyrido[1,2,3-ij][1,2,4]benzoxadiazine-6-carboxylic acid], C17H19FN4O4, the carbonyl and carboxyl groups are coplanar with the quinoline ring, making a dihedral angle of 2.39 (2)°. The piperazine ring adopts a chair conformation and the oxadiazinane ring displays an envelope conformation with the CH2group at the flap displaced by 0.650 (2) Å from the plane through the other five atoms. The molecular structure exhibits anS(6) ring motif, owing to an intramolecular O—H...O hydrogen bond. In the crystal, weak C—H...F hydrogen bonds link molecules into layers parallel to theabplane.

Convective heat transfer of supercritical CO2 cooled in a vertical circular tube has been numerically investigated by using the computational fluid mechanics code FLUENT. The objectives of this paper are to predict the heat transfer coefficient and to study the supercritical convective heat transfer of CO2 under uniform heat flux. Simulation starts with four cases, including a physical model, mathematical model, mesh independency, and solution method. Based on the mesh size of 80 x 500 in the radial and axial directions with near-wall resolution of less than 1, the low Reynolds number turbulence model proposed by Lam and Bremhorst (LB) model is adopted to investigate the heat flux effect, buoyancy effect on flow direction, and buoyancy effect on fluid flow. The results show that the LB low-Reynolds-number turbulence model agrees well with the experimental data. Buoyancy effect significantly affects the fluid flow and heat transfer characteristics in turbulent flow, which enhances heat transfer in upward flow, and impairs it in downward flow.

对负荷从平均值、不确定性和历史极大值3个方面进行描述;建立可以同时考虑这3个方面的混合整型非线性(MINLP)集成规划模型.针对具体算例,利用灵敏度分析方法对负荷3个方面进行分析,分别考察其对三联供系统各设备最优容量及经济性的影响.研究结果表明:燃气轮机容量主要取决于平均负荷,供热设备容量之和等于热负荷历史极大值,供冷设备容量之和等于冷负荷历史极大值,最大购电量对历史极大值灵敏,废热换热器对负荷不确定性灵敏,系统年总费用节省率主要取决于平均负荷.

This paper analyzes the work principle,mathematical model and main parameters for the two-phase flow cooling system driven by mechanical pump.Temperature distribution,resistance and flow mass of main components in the active two-phase cooling system driven by mechanical pump are experimen-tally studied.Heat transfer of the system is calculated and analyzed.The study results indicate that: when the temperature wave of the condensation boundary approaches 30 ℃,the difference between inlet and outlet temperatures can be kept less than 0.3 ℃ and the temperature change with time is less than 0.4 ℃,along the 10 m evaporation section.Analysis indicates that the two-phase flow cooling system driven by mechanical pump is of well isothermal characteristics and stable heat transfer.Calculation and analysis also indicate that this system can realize larger heat transfer with smaller energy consumption,which improves the work capa-bility of the active heat control system.

Against the surge problem of the jet fan influenced by the piston wind in channels,an anti-surge equipment is introduced.The flow fields of the jet fan both with and without anti-surge equipment is simulated via the software of Fluent.A comparison is also carried out between two flow fields.The results of the simulation show that the anti-surge equipment can improve the flow field of the jet fan substantially.So this anti-surge equipment can prevent the surge of the jet fan effectively.

Building cooling heating & power (BCHP) system has advantages of energy saving and environment protection. Accurate feasibility evaluation and rational match between energy supply and energy demands are necessary for the realization of advantages of BCHP system. The influence of energy demands on the optimal facility scheme and feasibility of BCHP system needs especially to be studied. Mixed-integer nonlinear programming model is established with integrated optimization of facility scheme and operation strategy of BCHP system. A series of energy demands with different heat-electricity ratio and cooling-electricity ratio are achieved based on the energy demands of a hotel. Sensitivity analysis about energy demands ratios is carried out in this paper to study their influence on optimal capacity of facilities and feasibility indices. And the reason of the results is analyzed. Indices of feasibility evaluation include annual cost, annual cost saving rate and annual natural gas saving rate. It is shown in result that energy demands of different type have different weight in optimal capacities. Optimal capacities of facilities should be designed with consideration of all three kinds of energy demands. Different feasibility evaluation are achieved with different indices. The BCHP system is preferable for buildings with high heat demand.

The two-phase mechanical pumped cooling loop(MPCL)by using CO_2 as the working fluid is a promising thermal control system which is just like a heat pipe to realize heat extraction from ener-electrical equipment by phase change efficiently.A brief review of system design and work principle was presented and a proposed experimental system was described.In order to apply CO_2 as a high quality work fluid,tests are performed to clearly comprehend its capability and to characterize the operation in different conditions.Special attention is paid to the system dynamic working characteristics under different conditions such as variation heat load and mass flow process.According to the experimental findings,the transient liquid transfer between the main loop and accumulator is analyzed to explain the temperature or pressure fluctuation in the accumulator and evaporator.It is concluded that the work fluid flowing into or out of the accumulator causes the absolute pressure and the temperature fluctuate in the accumulator,and the evaporator temperature would change as the following.At last,some characters were analyzed,it is demonstrated that a CO_2 MPCL presents a good performance and has more stable and robust characteristics for the special operation than the system by using other work fluid.

In the title compound, C9H14O3, the cyclohexenone ring has an envelope conformation; the flap atom (with the hydroxymethyl groups attached) is displaced by 0.582 (4) Å from the plane of the other five ring atoms. The crystal structure contains an intermolecular O—H...O hydrogen-bonded ring.

The title compound, C(21)H(18)O(3)S, is the E isomer, the ester -oxy link being trans to one of the phenyl groups. The planes of the phenyl substituents at the vinyl C atoms form a dihedral angle of 66.32 (7)° with each other. The vinyl group shows noticeable non-planarity, the C(Ph)-C=C-C(Ph) torsion angle being 8.4 (3)°.

The paper proposes two alternative approaches for the design of a dynamic model for an Organic Rankine Cycle (ORC) to be used for the design of control and diagnostics systems. The model has been developed in Modelica language and simulated with Dymola. The two modeling approaches, based on moving boundary and discretization techniques, are compared in terms of accuracy, complexity and simulation speed. Compared to experimental data simulations evidence that while both models have good accuracy. And the moving boundary model is faster, therefore more suitable for control design applications.

The second stage alpha magnetic spectrometer AM2-02 is the first large magnetic spectrometer that will be lunched to the space,the cryogenic ground support equipment(CGSE) is used to cool down the AMS02 magnet and fill superfluid helium into the magnetic Dewar of AMS-02.The design,manufacture and test of CGSE will be designed,manufactured,tested in China.The simulator will also be manufactured to test the CGSE.In this paper,the scheme, structure feature and function of the simulator is introduced,the strength calculation is verified.

The startup of a two-phase cooling system is a complex transient phenomenon, especially for the mechanically pumped two-phase cooling loop (MPCL), which is a promising thermal control method for extracting heat from large electronic equipments efficiently. In this paper, the system design and work principle as well as the test setup of an MPCL are presented and the startup processes of the MPCL are studied. The experiments on the startup processes under variety of conditions were carried out. Special attention has been paid to the startups of the system in different evaporative temperature, various mass flow or heating load and some abnormal startup prehistory. The transient flow exchange between the main loop and accumulator was observed and discussed according to different startup sections, which have been identified as pre-condition, pump startup and heat load startup. During the startup processes, the system presents a good stability and each part of the system performs a reasonable temperature wave, except some superheat phenomena in the evaporator. The superheat is mainly related to evaporative temperature and the initial liquid distribution in the evaporator. In general, the lower the evaporative temperature is, the higher superheat occurs. In conclusion, the startup processes in different situations may cause some liquid superheats and evaporator temperature overshoots, but they will not affect much on the steady state operation of the MPCL.

Factors that influence the performance of metal wire-mesh filters are summarized in this paper to give some recommendations for the better operation of the filter. Based on analyzing the mechanism of filtration, some parameters which affect the filtration efficiency, pressure drop or residual pressure drop, such as structure of the mesh, cycle index, filtration velocity, fluid concentration and temperature, compressibility of filter cake, maximum permission pressure drop and backflowing pressure, are discussed. It is found that these factors are affected by one another and should be considered simultaneously to get desired performance for the filter.

在以二氧化碳为工质的新型空间两相流冷却系统-机械泵驱动两相流冷却系统的实验过程中发现,在热量加载的同时在蒸发器出口将有过热现象产生.进一步的实验研究得出结论当启动过程蒸发温度越低,蒸发器出口的过热度也就越大,同时从过热状态变为两相状态所产生的压力脉冲也越大.通过经典核化理论的角度分析指出该现象的产生主要和工质的物性有关,又统计物理学和动力学成核理论方面分析指出随着蒸发温度的升高,核态沸腾产生气泡的直径变小,所以需要更少的热量就能推动从过热的亚稳态到更加稳定的两相状态的转变.

The system performance analysis and optimization of an organic Rankine cycle (ORC) system using HFC-245fa (1,1,1,3,3-pentafluoropropane) as working fluid driven by exhaust heat is presented. The thermodynamic performances of an ORC system under disturbances have been analyzed. The results show: maximizing the usage of exhaust heat as much as possible is a good way to improve system output net power and efficiency; the degree of sub-cooling at the condenser outlet should be small (0.5–0.6K); when the ambient temperature is too high, the system output net power and efficiency will deteriorate with the departure from nominal state possibly exceeding 30%. According to the running environment, choosing a proper nominal state is a good idea for improving the system output net power and efficiency.

With finite element analysis software ANSYS, simulates the flow field and the temperature field inside the heat passage of glass curtain wall applying natural ventilation and mechanical ventilation for the ward building in Shanghai First People’s Hospital, and finds that natural ventilation effect can not be realized and that applying mechanical ventilation can achieve good ventilation effect and save energy. For improving natural ventilation effect, proposes setting an inner glass at a distance of about 0.8 m from the external wall, and simulation results show that air outlet velocity can reach about 2.3 m/s and heat can be effectively removed from curtain wall. Simulates the velocity and temperature fields inside glass curtain walls with various widths of curtain wall and heights of air inlet and outlet under the condition of the same boundary and curtain wall height as the above model, considers the curtain wall width of 1.4 m and the air inlet and outlet height of about 0.35 m optimal design dimensions.