摘要： Management of patients requiring temporary, mechanical hemodynamic support during high-risk percutaneous coronary intervention (PCI) or in cardiogenic shock is rapidly evolving. With the availability of the Impella 2.5, CP, 5.0, LD, and RP percutaneous mechanical circulatory support devices, there is a need for continued surveillance of outcomes. Three factors underline the importance of a registry for these populations. First, large randomized trials of hemodynamic support, involving cardiogenic shock, are challenging to conduct. Second, there is increasing interest in the use of registries to provide "real-world" experience and to allow the flexibility to evaluate individual patient uses and outcomes. Third, current, large databases have not captured the specific impact of mechanical support treatment of cardiogenic shock. The predecessor to the catheter-based ventricular assist devices registry, known as USpella, began in 2009 with paper data acquisition but beginning in 2011 transferred to electronic data capture, enrolling 3,339 patients through 2016. Throughout, registry data have been used to assess the outcomes of Impella therapy, leading to 8 publications and 4 Food and Drug Administration premarket approvals covering multiple indications and Impella devices. Going forward, the registry will continue to assess not only in-hospital outcomes but long-term follow-up to 1 year. In addition, data management will be enhanced to assess quality and clinical experiences. The registry will also provide a mechanism for postmarketing surveillance. This manuscript reviews the ongoing catheter-based ventricular assist devices registry design, management, and contributions of the registry data. The upgraded registry will provide a more robust opportunity to assess acute and late outcomes of current and future device use worldwide.

关键词： C3N   Nanosheet   Molecular dynamics   Defects   Cracks  

摘要： The purpose of this study is to investigate the mechanical properties of a new two-dimensional graphene like material, crystalline carbon nitride with the stoichiometry of C3N. The extraordinary properties of C3N make it an outstanding candidate for a wide variety of applications. In this work, the mechanical properties of C3N nanosheets have been studied not only in the defect-free form, but also with critical defects such as line cracks and notches using molecular dynamics simulations. Different crack lengths and notch diameters were considered to predict the mechanical response at different temperatures under the uniaxial tensile loading. Our simulation results show that larger cracks and notches reduce the strength of the nanosheets. Moreover, it was shown the temperature rise has a weakening effect on the tensile strength of C3N. Our study can provide useful information with respect to the thermomechanical properties of pristine and defective graphene like C3N 2D material. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Closed ecological life support system   Functional-structural plant model   Knowledge-and-data-driven model   Mass balance model   Model evaluation   And model verification  

摘要： Modeling and the prediction of material flows (plant production, CO2/O-2 concentrations, H2O) is an important but challenging task in the design and control of closed ecological life support systems (CELSS). The aim of this study was to develop a novel knowledge-and-data-driven modeling (KDDM) approach for simultaneously simulating plant production and CO2/O-2 concentrations in a closed system of plants and humans by integrating mechanistic and empirical models. The KDDM approach consists of a 'knowledge-driven (KD)' sub-model and a 'data-driven (DD)' sub-model. The KD sub-model describes hourly and up to daily plant photosynthesis, respiration and assimilation partitioning using the components of GreenLab and TomSim models. The DD sub-model describes the dynamics of CO2 production and O-2 consumption by the crew member using a piecewise linear model. The two sub-models were integrated with a mass balance model for CO2/O-2 concentrations in a closed system. The KDDM was applied with a two-person, 30-day integrated CELSS test. This model provides accurate computation of both the dry weights of different plant compartments and CO2/O-2 concentrations. The model also quantifies the underlying material flows among the crew members, plants and environment. This approach provides a computational basis for lifetime optimization of cabin design and experimental setup of CELSS (e.g., environmental control, planting schedule). With extension, this methodology can be applied to a half-closed system such as a glasshouse.

关键词： hemodynamic monitoring   mechanical circulatory support   left ventricular assist device   heart failure   pulmonary wedge pressure   heart transplantation  

摘要： Proper timing of left ventricular assist device (LVAD) implantation in advanced heart failure patients is not well established and is an area of intense interest. In addition, optimizing LVAD performance after implantation remains difficult and represents a significant clinical need. Implantable hemodynamic monitoring systems may provide physicians with the physiologic information necessary to improve the timing of LVAD implantation as well as LVAD performance when compared with current methods. The CardioMEMS Heart sensor Allows for Monitoirng of Pressures to Improve Outcomes in NYHA Class III heart failure patients (CHAMPION) Trial enrolled 550 previously hospitalized patients with New York Heart Association (NYHA) class III heart failure. All patients were implanted with a pulmonary artery (PA) pressure monitoring system and randomized to a treatment and control groups. In the treatment group, physicians used the hemodynamic information to make heart failure management decisions. This information was not available to physicians for the control group. During an average of 18 month randomized follow-up, 27 patients required LVAD implantation. At the time of PA pressure sensor implantation, patients ultimately requiring advanced therapy had higher PA pressures, lower systemic pressure, and similar cardiac output measurements. Treatment and control patients in the LVAD subgroup had similar clinical profiles at the time of enrollment. There was a trend toward a shorter length of time to LVAD implantation in the treatment group when hemodynamic information was available. After LVAD implantation, most treatment group patients continued to provide physicians with physiologic information from the hemodynamic monitoring system. As expected PA pressures declined significantly post LVAD implant in all patients, but the magnitude of decline was higher in patients with PA pressure monitoring. Implantable hemodynamic monitoring appeared to improve the timing of LVAD implantatio

关键词： Silicene   Nanoindentation   Mechanical properties   Molecular dynamics  

摘要： In the present study, molecular dynamics simulations were carried out to study the mechanical behavior and response of a single layer, rectangular, planar and pristine silicene sheet during nanoindentation process. The nanoindentation simulation on the silicene sheet was done using a spherical diamond indenter and the different force vs depth of indentation curves at different conditions of temperature, indenter radius and depth of indentation were obtained. The variation of mechanical properties like maximum force, hardness and Young's modulus were studied with respect to temperature, indenter radius and depth of indentation by varying one parameter while keeping the other two parameters constant. The deformation behavior of the silicene sheet up to failure was thoroughly studied and the mechanical properties like maximum force bearing capacity, maximum hardness and Young's modulus of the silicene sheet were calculated. The maximum force and hardness of the silicene sheet at its maximum indentation depth of 39.5 angstrom are found to be 286.3 nN and 461.2 GPa respectively. The Young's modulus of the silicene sheet is found to be 176.9 GPa which is in close agreement with the existing literature reported value of 178 GPa. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Hybrid   TENG   Self-powered multifunctional sensors  

摘要： Collecting mechanical energy in the surrounding environment to power small electronic devices is an ideal method as a green and clean power source. Based on the working mechanism and the advantages of triboelectric nanogenerator (TENG), a robust rolling friction contact-separation mode TENG (CS-TENG) has been fabricated for harvesting vertical rotation energy by utilizing the integrated cylindrical surface with the conjunction of rolling contact electrification and electrostatic induction. The output current of the CS-TENG can maintain 96% (origin: 1.72 mu A, final: 1.66 mu A) after two days continuous work a rotation speed of 300 r/min. Furthermore, an electromagnetic and triboelectric hybrid contact-separation mode nanogenerator (HCS-TENG) has been further designed by coupling magnets in the rolling cylinders with copper coils as an electromagnetic generator (EMG) in the acrylic cylinder to implement the multi-functional properties. The gear transmission structure makes the device more facile to be installed on the rotation objects. The output performances of CS-TENG and EMG under various rotation speeds were systematically studied. It shows that the CS-TENG with six units can deliver an output power of 0.15 mW/cm(2) and the 100 mu F capacitor can be charged to 6 V in less than 1 min by the hybridized nanogenerator at a rotating rate of 700 r/min. In addition, utilizing the output signal's intrinsic characteristics of CS-TENG, a self-powered rotation speed and displacement sensor using the dual cylinder structure TENG has been achieved for these rotating mobile devices that are inconvenient to get an additional power supply in the grimmest circumstances such as moon car or other celestial and tough environment detection equipment. This multifunctional TENG device reveals a significantly potential application in the grimmest circumstances as power source, self-powered electronics and sensor systems.

关键词： 运动力学   机械结构   设计应用  

摘要： 运动力学是研究物体运动规律的,通常指的是物体的运动.随着现代运动力学理论的不断延伸发展,其在很多领域已经有了比较深入的应用.基于此,在本文的研究中,主要对运动力学在机械结构设计中的应用进行论述,对运动力学的应用价值和作用进行分析,希望可以对相关机械结构设计领域对运动力学的科学运用起到一定的参考和启发作用.

关键词： Polychloroprene   Strain-induced crystallization   X-ray  

摘要： Polychloroprene rubber is often quoted as an example of strain-crystallizing elastomer;however, this fundamental property, known to impart good mechanical properties and fatigue resistance, has received much less attention in this class of compounds than natural rubber. The present paper relates systematic investigations combining mechanical and X-ray diffraction measurements. Crystallization kinetics are first investigated based on tensile impact tests. An approximately logarithmic time-dependence is found for the crystalline content and the time-constants are estimated at various temperatures. The impact of strain-induced crystallization on stress-strain curves under mechanical cycling conditions is further assessed. It is demonstrated that one main effect of strain-induced crystallization is a partial relaxation of the strain experienced by the amorphous fraction, although stress-hardening is simultaneously observed. Based on the stress-optical law, the contribution of the amorphous phase to the stress is shown to level off after crystallization onset, and stress-hardening is attributed to crystallite networking. The crystallite network rapidly disintegrates at the beginning of recovery, and the stress-optical law shows that the amorphous fraction becomes the only contributor to the stress at still non-negligible crystalline contents. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Mechanical vertical drilling tool   torsional vibration   eccentric block   gravity sensitivity   non-linear analysis  

摘要： In present, the drilling industry have to face the reality of low oil and gas prices, fully mechanical vertical drilling tool is likely to become the best choice for vertical drilling in the future. Without electric measurement and control system, the mechanical vertical drilling tool has a mechanically stable platform with gravity sensitivity. The stable platform included an eccentric block which is not only sensitive to gravity but also severely affected by torsional vibration. In this article, we reveal the dynamics of eccentric block under the effect of torsional vibration, which is the key element of the well deviation control accuracy in mechanical vertical drilling tool. The dynamic model of eccentric block is established using Lagrangian equation and Coulomb friction, and the law of dynamic characteristics under the effect of different amplitudes and period of torsional vibration is found. The results show that, with the deviation angle and eccentric torsion moment of eccentric block is increased, the resistance to torsional vibration increases. While the frequency of torsional vibration decreases, a subordinate period gradually appears after the rotation speed value of omega is less than I rad/s, the torsional vibration with large amplitude and high frequency is detrimental to the stability of the eccentric block. In addition, the largest Lyapunov exponent is estimated using the time series of simulation, the dynamics of eccentric block under the effect of torsional vibration can be switched four types, and the maximum and minimum values of largest Lyapunov exponent are 3.99 X 10(-2) and -2.98 X 10(-2), which means with the state of torsional vibration changes and the response of eccentric block would be transformed to chaos.

关键词： High entropy alloy   Mechanical alloying   Sintering   Diffusion  

摘要： This work correlates the densification behaviors of high entropy alloy powders with the alloying order. Mechanically alloyed powders (CoFeNi, CoFeNiCr, CoFeNiCrMn and CoFeNiCrMnAl alloys) were non-isothermally sintered using dilatometer. It was demonstrated that when the alloying order or the number of alloying elements were increased from 3 elements to 6 elements, sintering kinetics were changed. Materials exhibit sluggish grain growth, reducing densification rates and increasing activation energies of sintering, with increasing configurational entropy. Increasing trend of micro-hardness also indicates the better mechanical properties of such alloys. (C) 2018 Elsevier B.V. All rights reserved.