摘要：Cardiovascular diseases are the leading cause of morbidity and mortality throughout the world underlining the importance of efficient treatments including disease modeling and drug discovery by cardiac tissue ***,the predictive power of these applications is currently limited by the immature state of the ***,we developed gelatin hydrogels chemically crosslinked by genipin,a biocompatible crosslinker,as cell culture *** rat cardiomyocytes appear synchronous beatingwithin 2 days after seeding on ***,we applied the electrical stimulation as a conditioning treatment to promote the maturation of cardiomyocytes cultured on the *** results show that electrical stimulation improves the organization of sarcomeres,establishment of gap junctions,calcium-handling capacity and propagation of pacing signals,thereby,increase the beating velocity of cardiomyocytes and responsiveness to external *** above system can be applied in promoting physiological function maturation of engineered cardiac tissues,exhibiting promising applications in cardiac tissue engineering and drug screening.

摘要：The full-duplex(FD) based wireless communication devices,which are capable of concurrently transmitting and receiving signals with a single frequency band,suffer from a severe self-interference(SI) due to the large power difference between the devices' own transmission and the useful signal comes from the remote transmitters. To enable the practical FD devices to be implementable,the SI power must be sufficiently suppressed to the level of background noise power,making the received signal-to-interference-plus-noise ratio(SINR) satisfy the decoding requirement. In this paper,the design and implementation of the duplexer for facilitating SI cancellation in FD based wireless communications are investigated,with a new type of duplexer(i.e. an improved directional coupler) designed for improving the spatial suppression of the SI power. Furthermore,the practical circuit boards are designed and verified for the proposed prototype,showing that the spatial suppression capability may be up to 36 d B(i.e. much higher than that attainable in the commonly designed ferrite circulator) by using the proposed design.

摘要：To evaluate the efficiencies of different sampling methods for a rare and clustered population, we investigated the sampling effects for the two species Tamarix chinensis (Salt cedar) and Elaeagnus angustifolia (Russian olive) in western Inner Mongolia with two-stage sequential sampling, which is a new sampling method, traditional simple random sampling and two-stage sampling. Based on two-stage sequential sampling and two-stage sampling, each population was partitioned into four primary sampling units, and then two of them were randomly selected. Sampling designs were simulated based on the conditions of five secondary sampling unit areas, two criterion values, five initial secondary sampling units and two sequential secondary sampling units in 1000 repetitions. To evaluate the performance of the sampling designs for each method, the variance and relative error of the density estimates were used. The relative sampling efficiencies of the three sampling methods were compared using the same final sampling sizes. We analyzed the sampling efficiency generated by two-stage sequential sampling and found that it yielded smaller variances than those of simple random sampling and two-stage sampling in all sampling designs, and that two-stage sampling was more efficient than simple random sampling. Density estimates from the two-stage sequential sampling were very close to the true values. We also determined the optimum secondary sampling unit areas for the two species in the two-stage sequential sampling. It was best for Tamarix chinensis and Elaeagnus angustifolia when the secondary sampling unit areas were 200 and 100 m2 , respectively.

摘要：The precise design and fabrication of biomaterial scaffolds is necessary to provide a systematic study for bone tissue engineering. Biomaterial scaffolds should have sufficient stiffness and large porosity. These two goals generally contradict since larger porosity results in lower mechanical properties. To seek the microstructure of maximum stiffness with the constraint of volume fraction by topology optimization method, algorithms and programs were built to obtain 2D and 3D optimized microstructure and then they were transferred to CAD models of STL format. Ti scaffolds with 30% volume fraction were fabricated using a selective laser melting （SLM） technology. The architecture and pore shape in the metallic biomaterial scaffolds were relatively precise reproduced and the minimum mean pore size was 231μm. The accurate fabrication of intricate microstructure has verified that the SLM process is suitable for fabrication of metallic biomaterial scaffolds.

摘要：In this paper, we present a three-dimensional（3D） vacuum packaging technique at a wafer level for a radio frequency micro-electromechanical system（RF MEMS） resonator, in which low-loss silicon vias is used to transmit RF ***–Sn solder bonding is adopted to provide a vacuum encapsulation as well as electrical conductions. A RF model of the encapsulation cap is established to evaluate the parasitic effect of the packaging, which provides an effective design solution of 3D RF MEMS encapsulation. With the proposed packaging structure, the signal-to-background ratio（SBR） of 24 dB is achieved, as well as the quality factor（Q-factor） of the resonator increases from 8000 to 10400 after *** packaged resonator has a linear frequency–temperature（ f –T） characteristic in a temperature range between 0℃ and 100℃. And the package shows favorable long-term stability of the Q-factor over 200 days, which indicates that the package has excellent hermeticity. Furthermore, the average shear strength is measured to be 43.58 MPa among 10 samples.

摘要：For the surgical treatment of cardiovascular disease(CVD),there is a clear and unmet need in developing small-diameter(diameter<6 mm)vascular *** our previous work,sulfated silk fibroin(SF)was successfully fabricated as a potential candidate for preparing vascular grafts due to the great cytocompatibility and ***,vascular graft with single layer is difficult to adapt to the complex internal *** this work,polycaprolactone(PCL)and sulfated SF were used to fabricate bilayer vascular graft(BLVG)to mimic the structure of natural blood *** enhance the biological activity of BLVG,nicorandil(NIC),an FDA-approved drug with multi-bioactivity,was loaded in the BLVG to fabricate NIC-loaded *** morphology,chemical composition and mechanical properties of NIC-loaded BLVG were *** results showed that the bilayer structure of NIC-loaded BLVG endowed the graft with a biphasic drug release *** in vitro studies indicated that NIC-loaded BLVG could significantly increase the proliferation,migration and antioxidation capability of endothelial cells(ECs).Moreover,we found that the potential biological mechanism was the activation of PI3K/AKT/eNOS signaling ***,the results effectively demonstrated that NIC-loaded BLVG had a promising in vitro performance as a functional small-diameter vascular graft.

摘要：Dextran-hyaluronate （Dex-HA） based supermacroporous cryogel scaffolds for soft tissue engineering were prepared by free radical cryo-copolymerization of aqueous solutions containing the dextran methacrylate （Dex-MA） and hyaluronate methacrylate （HA-MA） at various macromonomer concentrations under the freezing condition. It was observed that the suitable total concen- tration of macromonomers for the preparation of Dex-HA cryogel scaffold with satisfied properties was 5% （w/w） at the HA-MA concentration of 1% （w/v）, which was then used to produce the test scaffold. The obtained cryogel scaffold with 5% （w/w） macromonomer solution had high water permeability （5.1 × 10 ^-2m2） and high porosity （92.4%）. The pore diameter examined by scanning electron microscopy （SEM） was in a broad range of 50-135 um with the mean pore diameter of 91 um. Furthermore, the cryogel scaffold also had good elastic nature with the elastic modulus of 17.47±1.44 kPa. The culture of 3T3-L1 preadipocyte within the scaffold was investigated and observed by SEM. Cells clustered on the pore walls and grew inside the scaffold indicating the Dex-HA cryogel scaffold could be a promising porous biomaterial for applications in tissue engineering.

摘要：为探讨薄壁高筋筒形件整体内高压成形的可行性,采用力学分析和数值模拟相结合的方法,研究了一端约束、一段自由约束特征的薄板(加强筋)失稳的力学条件。基于"板条梁"理论给出了筋板失稳欧拉力的数学表达式。结合数值模拟分析了筋板高度和内径对失稳的影响。结果表明:对于1Cr18Ni9Ti薄壁高筋筒形件胀形量为20%时其临界高厚比和径厚比分别为14和30。随着高厚比增大,成形性降低,随着径厚比增大,成形性提高。绘制了内高压成形窗口图,为薄壁高筋筒形件内高压成形规律的深入研究和内高压成形工艺设计奠定了理论基础。

摘要：The addition of a buffer layer can improve the device＇s secondary breakdown voltage, thus, improving the single event burnout （SEB） threshold voltage. In this paper, an N type linear doping buffer layer is proposed. According to quasi-stationary avalanche simulation and heavy ion beam simulation, the results show that an op- timized linear doping buffer layer is critical. As SEB is induced by heavy ions impacting, the electric field of an optimized linear doping buffer device is much lower than that with an optimized constant doping buffer layer at a given buffer layer thickness and the same biasing voltages. Secondary breakdown voltage and the parasitic bipolar turn-on current are much higher than those with the optimized constant doping buffer ~ayer. So the linear buffer layer is more advantageous to improving the device＇s SEB performance.

摘要：In this paper,we introduce a novel approach to automatically regulate receptive fields in deep image parsing *** previous work which placed much importance on obtaining better receptive fields using manually selected dilated convolutional kernels,our approach uses two affine transformation layers in the network’s backbone and operates on feature *** maps are inflated or shrunk by the new layer,thereby changing the receptive fields in the following *** use of end-to-end training,the whole framework is data-driven,without laborious manual *** proposed method is generic across datasets and different *** have conducted extensive experiments on both general image parsing tasks,and face parsing tasks as concrete examples,to demonstrate the method’s superior ability to regulate over manual designs.