Porous agarose/Gd-hydroxyapatite composite bone fillers with promoted osteogenesis and antibacterial activity

Artificial bone fillers are essentially required for repairing bone defects, and developing the fillers with synergistic biocompatibility and anti-bacterial activity persists as one of the critical challenges. In this work, a new agarose/gadolinium-doped hydroxyapatite filler with three-dimensional porous structures was fabricated. For the composite filler, agarose provides three-dimensional skeleton and endows porosity, workability, and high specific surface area, hydroxyapatite (HA) offers the biocompatibility, and the rare earth element gadolinium (Gd) acts as the antibacterial agent. X-ray photoelectron spectroscopy detection showed the doping of Gd in HA lattice with the formation of Gd-HA interstitial solid solution. Attenuated total reflection Fourier transform infrared spectroscopy imaging suggested chemical interactions between agarose and Gd-HA, and the physical structure of agarose was tuned by the Gd-doped HA. Cytotoxicity testing and alizarin red staining experiments using mouse pro-osteoblasts (MC3T3-E1) revealed remarkable bioactivity and osteogenic properties of the composite fillers, and proliferation and growth rates of the cells increased in proportion to Gd content in the composites. Antibacterial testing using the gram-positive bacteria S. aureus and the gram-negative bacteria E. coli indicated promising antibacterial properties of the fillers. Meanwhile, the antibacterial properties of composite filles were enhanced with the increase of Gd content. The antibacterial fillers with porous structure and excellent physicomechanical properties show inspiring potential for bone defect repair.     

Remarkably enhanced energy storage properties of lead-free Ba0.53Sr0.47TiO3 thin films capacitors by optimizing bottom electrode thickness

The lead-free Ba_0.53Sr_0.47TiO₃ (BST) thin films buffered with La_0.67Sr_0.33MnO₃ (LSMO) bottom electrode of different thicknesses were fabricated by pulsed laser deposition method on a (001) SrTiO₃ substrate. It was found that the roughness of electrode decreases and substrate stress relaxes gradually with the increase of LSMO thickness, which is beneficial for weakening local high electric field and achieving higher E_b. Therefore, the recoverable energy density (W_rec) of BST films can be greatly improved up to 67.3 %, that is, from 30.6 J/cm³ for the LSMO thickness of 30 nm up to 51.2 J/cm³ for the LSMO thickness of 140 nm after optimizing the LSMO thickness. Furthermore, the thin film capacitor with a 140 nm LSMO bottom electrode shows an outstanding thermal stability from 20 °C to 160 °C and superior fatigue resistance after 10⁸ electrical cycles with only a slightly decrease of W_rec below 1.6 % and 3.7 %, respectively. Our work demonstrates that optimizing bottom electrodes thickness is a promising way for enhancing energy storage properties of thin-film capacitors.     

Evolution mechanism of the microstructure and mechanical properties of plasma-sprayed yttria-stabilized hafnia thermal barrier coating at 1400 °C

Yttria stabilized hafnia (Hf_0.84Y_0.16O_1.92, YSH16) coatings were sprayed by atmospheric plasma spraying (APS). The effects of thermal aging at 1400 °C on the microstructures, mechanical properties and thermal conductivity of the coatings were studied. The results show that the as-sprayed coating was composed of the cubic phase, and the nano-sized monoclinic (M) phase was precipitated in the annealed coating. The presence of M phase effectively constrained the sintering of the coating due to its superior sintering-resistance. The Young's modulus kept at a nearly same level of ~78 GPa even after annealing, and the coating annealed for 6 h yielded a maximum value of hardness but revealed a declining tendency in the Vicker's hardness with prolonged sintering time. The thermal conductivity increased from 0.8-0.95 W m^-1 K^-1 at as-sprayed state to 1.6 W m^-1 K^-1 after annealing at 1400 °C for 96 h. The dual-phase coating is promising to serve at temperatures above 1400 °C due to its excellent thermal stability and mechanical properties.     

复杂采空区充填开采对地面建筑的影响研究

矿山地下开采引起的围岩应力变化及地表变形影响着地面建筑物的安全。采用ABAQUS有限元软件对金属矿山充填开采引起的岩体变形及地表移动规律进行了研究。以矿山实际开采现状及实测数据为基础，建立了具有复杂空间结构的三维地层模型，利用子程序SIGINI编程施加地应力，采用修正Mohr-Coulomb模型模拟岩体，计算得出：由于围岩力学强度较高，开采引起顶板下沉量相对较小，充填对于控制底鼓具有一定抑制作用；预留矿柱主要承受较大竖向压应力，矿柱尺寸越小压缩量越大；地表充填站位于采空区边缘位置，水平及竖向位移相对较小，地表变形主要集中在采空区中部位置。研究成果可为矿山安全开采提供依据，为地面监测点的选择提供参考。     

某高校既有建筑室内人员相关VOCs目标污染物的实测分析

为研究高校既有建筑室内人群散发对室内VOCs的影响，对高校不同人群样本的教室及会议室两类典型人群密集房间，共82个人群样本对象进行了VOCs采样分析，得到不同实际场景下的人员相关的VOCs浓度水平，并对其潜在的影响因素进行分析。结果表明，共确认了29种与室内人员相关的高检出率且较高浓度值的物质，包括芳香族化合物9种，烷烯烃类9种，酮类和醛类8种，醇酯类以及卤化物3种，并得到主要VOCs物质的浓度水平和I/O比。对影响因素的统计分析表明，室内人员密度、季节和房间类型对不同VOCs物质存在显著性影响，其中季节性因素对目标VOCs污染物影响最为广泛，其次是房间类型与室内人员密度。该研究可为进一步了解人员密集室内VOCs污染现状及控制策略提供一定的科学参考。     

A novel utilized method of tar derived from biomass gasification for fabricating binder-free all-solid-state hybrid supercapacitors

As an industrial pollutant, tar derived from biomass gasification is used as the precursor for fabricating a novel carbon-metal hydroxides composite electrode. A slurry (the mixture of tar, KOH and melamine) is daubed uniformly onto the nickel foam, which is directly carbonized to form NPC@LDH electrode material. This electrode is further coated with NiCo-LDH nanosheets using an electrodeposition method to form NF@NPC@LDH. The newly made NF@NPC@LDH electrode exhibits a high specific capacity of 9.6 F cm⁻² at a current density of 2 mA cm⁻² and good rate performance (55.3% retention). Furthermore, a hybrid NF@NPC@LDH//NF@PC all-solid-state supercapacitor is fabricated, and the device exhibits high energy density of 1.28 mWh cm⁻³ at a power density of 8.04 mW cm⁻³, low resistance and good cycling stability.     

规则RA码在混合信道上的高斯估计

将高斯估计方法运用到规则重复累积（RA）码在具有加性白色高斯噪声和删除干扰的混合信道上的性能分析中．导出了RA码在该信道上概率密度进化的递归等式和误码率的解析表达式。仿真结果验证了解析结果的正确性。因此解析结果可以直接用来预测RA码在混合信道上的性能。     

Analysis of three-dimensional proximity effect in electron-beam lithography

In most of the proximity effect correction schemes, a two-dimensional model of proximity effect is employed by ignoring or averaging the variation of exposure along the depth dimension in the resist. However, as the feature size continues to decrease, the relative variation becomes significant so that it may need to be taken into account in proximity effect correction. In this study, the three-dimensional (3-D) proximity effect is analyzed in detail through computer simulation as a first step toward developing a 3-D proximity effect correction scheme. Effects of the parameters such as beam energy, resist thickness, feature size, developing threshold, etc., on the 3-D spatial distribution of exposure in the resist, in particular, depth-dependent proximity effect, are considered in the analysis. Results from the extensive simulation are presented in this paper.     

STUDY OF MECHANISM OF RQ EMBRITTLEMENT OF Fe_(73.5)Cu_1-Nb_3Si_(13.5)B_9 NANOCRYSTALLINE SOFT MAGNETIC ALLOY

Rapidly quenching embrittlement (RQE) sometimes appears in Fe73.5Cu1Nb3Si13.5B9 nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism of RQE has been elucidated in the recent works of current authors. It was believed that RQE is due to the structural relaxation but not related to a-Fe(Si) crystallization. In this paper, the high resolution TEM (HRTEM) method and image digital processing were applied to analyze the HRTEM images of two FINEMET rapidly quenched ribbons with different thicknesses in detail. In the thinner ductile sample, the ordering domains with the size of about 3nm are observed. In the thicker RQE sample, the metastable nanocrystalline domains with the size of 18nm are observed along with the structural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regions extend when RQE induced