天基跟踪层星座性能建模与仿真

随着高超声速武器技术的快速发展和实战化部署，美国有针对性地提出了建设国防太空架构跟踪层计划的设想。首先，介绍了跟踪层卫星主要设计性能参数；其次，建立了跟踪层星座覆盖性能分析模型、探测能力分析模型和跟踪性能分析模型；最后，通过仿真计算对跟踪层系统性能进行了分析，并推断了系统全星座最小卫星数量、探测灵敏度和全球目标最优跟踪精度等核心能力。分析结果对相关系统信息处理算法研究、载荷与星座方案设计具有重要参考价值。     

Effect of Gd doping on electrical transport properties of La0.8Sr0.2MnO3 polycrystalline ceramics

Gd doped La_0.8Sr_0.2MnO₃ (La_0.8-xGd_xSr_0.2MnO₃, LGSMO) ceramics were prepared by a sol-gel method. X-ray diffraction (XRD) patterns showed that all samples exhibited distorted perovskite structures, R_3c. When the Gd³⁺ content x > 0.03, the crystal structure changed to orthorhombic, Pnma. Scanning electron microscopy (SEM) images showed that the ceramics characterize high density and grain boundary connectivity, and higher Gd³⁺ doping decreased the grain size from 26.72 μm to 7.42 μm. The temperature dependence of resistivity showed a transition from a low-temperature metal to a high-temperature insulator. The resistivity increased with Gd doping content, and the metal-insulator transition temperature, T_P, increased first and then decreased, while the temperature coefficient of resistance (TCR) of the samples first decreased and then increased with Gd³⁺, and the magnetoresistance (MR) increased first and then decreased. The peak TCR at x = 0.06 was 5.18%·K^?1, and MR at 0.04 was 34.57%. The electrical transport properties of the ceramics were explained based on the double exchange (DE) interaction mechanism. The obtained material may have application prospects in magnetic devices and infrared detectors.     

Synthesis of strontium (Sr) doped hydroxyapatite (HAp) nanorods for enhanced adsorption of Cr (VI) ions from wastewater

The development of high-efficiency adsorbents for heavy metal ion removal from wastewater is highly desirable and challenging due to their synthesis complexity and low adsorption capacities. Herein, we reported the synthesis of strontium (Sr) doped hydroxyapatite (HAp) for the increased Cr (VI) adsorption. The effects of pH, temperature, and time on adsorption performances were studied. As a result, the Sr-HAp nanorods can achieve a Cr (VI) adsorption capacity of 443 mg/g, which is significantly higher than that of HAp nanorods (318 mg/g). To better understand the adsorption mechanism, the Langmuir isotherm model was established. The modeling results indicated that Langmuir monolayer chemical adsorption contributed to the efficient Cr (VI) ion removal for Sr-HAp nanorods adsorbents. The surface area and surface functional groups (O–H) contributed to the different Cr (VI) adsorption capacities between HAp and Sr-HAp.     

Fabrication of crescent-shaped ceramic microparticles based on single emulsion microfluidics

Ceramic microparticles have great potentials in various fields such as materials engineering, biotechnology, microelectromechanical systems, etc. Morphology of the microparticle performs an important role on their application. To date, it remains difficult to find an effective and controllable way for fabricating nonspherical ceramic microparticles with 3D features. This work demonstrates a method that combines UV light lithography and single emulsion opaque-droplet-templated microfluidic molding to prepare the crescent-shaped ceramic microparticles. By tailoring the intensity of UV light and flow rate of fluid, the shapes of microparticles are accordingly tuned. Therefore, varieties of crescent-shaped microparticles and their variations have been fabricated. After sintering, the crescent-shaped alumina ceramic microparticles were obtained. Benefitting from the light absorption and scattering behavior of most ceramic nanoparticles, this system can serve as a general platform to produce crescent-shaped microparticles made from different materials, and hold great potentials for applications in microrobotics, structural materials in MEMS, and biotechnology.     

Enhanced electrochemical performance of LiNi0.8Co0.1Mn0.1O2 via titanium and boron co-doping

Titanium and boron are simultaneously introduced into LiNi_0.8Co_0.1Mn_0.1O₂ to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti⁴⁺ ion replaces Li⁺ ion and reduces the cation mixing; B³⁺ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO₆] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g^-1 at 1 C and 155.5 mAh·g^-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi_0.8Co_0.1Mn_0.1O_2.     

加强自然资源领域安全生产管理措施建议研究

当前，安全生产事故频发，造成重大人员伤亡和财产损失，成为国家安全生产亟需解决的问题，按照新时期新要求，加强自然资源领域安全生产管理尤为重要。本文重点围绕自然资源领域涉及的土地资源、矿产资源、海洋资源以及测绘行业和地勘行业，通过调研及专家座谈，分析了我国自然资源领域安全生产管理的现状，存在的问题和产生的原因；结合新时期自然资源管理实际，以及地方和其他部门典型经验，从制度机制、标准化、信息化、人才培养等角度提出了加强我国自然资源领域安全生产管理的措施和建议，以供参考。     

42CrMo钢加热过程中的奥氏体晶粒尺寸演变

通过金相试验方法测定42CrMo钢在890~930 ℃下保温10~240 min后的晶粒尺寸。结果表明,42CrMo钢在加热到试验温度890~930 ℃时已经完全奥氏体化,保温过程中的晶粒生长属于正常生长;加热温度对晶粒尺寸的影响较大,保温时间对晶粒尺寸的影响较小;随保温时间的延长晶粒生长缓慢,晶粒尺寸与保温时间满足指数小于1的函数关系。基于试验数据,通过线性回归得到晶粒长大的Beck模型参数,通过非线性回归得到Sellars和Anelli模型参数,3个模型的预测精度都较好,而Anelli模型的适用性要高于Beck模型和Sellars模型,故在预测42CrMo钢的奥氏体晶粒长大规律时宜使用Anelli模型。     

Superhydrophobic aluminum alloy surface with excellent universality,corrosion resistance,and antifouling performance prepared without prepolishing

It is urgently necessary to seek more simple and effective methods to construct superhydrophobic metal surfaces to improve the corrosion resistance and antifouling performance. Herein, a facile method for fabricating superhydrophobic aluminum alloy surface is developed via boiling water treatment and stearic acid modification. It is noteworthy that no prepolishing on aluminum alloy is required and no caustic reagents and typical equipments are used during the preparation procedure. Therefore, the fabrication method is quite a simple and environment-friendly technique. Both micro- and nano-scaled binary structure forms at the resultant aluminum alloy surface while long alkyl chains are grafted onto the rough aluminum alloy surface chemically. Consequently, the resultant aluminum alloy exhibits outstanding superhydrophobicity. More importantly, the superhydrophobicity has excellent universality, diversity, stability, excellent corrosion resistance, and antifouling performance. The facile preparation, excellent superhydrophobic durability, and outstanding performance are quite in favor of the practical application.     

Optimisation of the spark plasma sintering process for high volume fraction SiCp/Al composites by orthogonal experimental design

Based on orthogonal experimental design (OED), the effects of the sintering pressure, sintering temperature and holding time on the mechanical properties of 50 vol% silicon carbide particle (SiCp)/2024Al composites prepared by spark plasma sintering (SPS) were investigated. The sintering pressure had the greatest effect on the density and bending strength of the material among these three factors, followed by sintering temperature and holding time. The optimised process conditions for producing the 50 vol% SiCp/2024Al were sintering at 550 °C for 5 min under 40 MPa, which resulted in a composite material with a density of 99.7% and good interface bonding with a comparatively high bending strength of 766.65 MPa. This work provides a promising method to produce high volume fraction composites that can meet high strength requirements.     

Synergy of Immunostimulatory Genetherapy with Immune Checkpoint Blockade Motivates Immune Response to Eliminate Cancer

Normalizing the tumor-induced immune deficiency in the immunosuppressive tumor microenvironment (TME) through increasing the efficient infiltration and activation of antitumoral immunity in TME is the core of promising immunotherapy. Herein, a Cyclo(Arg-Gly-Asp-d -Phe-Lys) (RGD) peptides-modified combinatorial immunotherapy system based on the self-assembly of the nanoparticles named RGD-DMA composed of RGD-PEG-PLA, methoxy poly(ethylene glycol)-poly(lactide) (MPEG-PLA) and 1,2-Dioleoyl-3-trimethylammonium-propane (DOTAP) is used to codeliver the immunostimulatory chemokine CCL19-encoding plasmid DNA (CCL19 pDNA) and immune checkpoint ligand PD-L1 inhibitor (BMS-1). The RGD-DMA/pCCL19-BMS-1 system not only exhibited significant inhibition of tumor progression but also induced locally high concentrations of immunostimulatory cytokines at tumor sites without causing an obviously systemic inflammatory response. The immunosuppressive TME is efficaciously reshaped by the coadministration of RGD-DMA/pCCL19 and BMS-1, as indicated by the activated T lymphocytes, increased intratumoral-infiltration of mature dendritic cells (DCs), and the repolarization of macrophages from pro-tumoral M2-phenotype toward tumoricidal M1-phenotype. The upregulated PD-L1 expression at tumor sites caused by the increased IFN-γ levels after immunostimulatory gene therapy further demonstrated the synergistic effects of BMS-1 in counteracting the inhibitory role of PD-L1 expression in antitumor immunity. Therefore, the combination of immunostimulating therapy and immune checkpoint inhibitor that synergistically target multiple immune regulatory pathways demonstrates significant potential as a novel immunotherapy approach.