Experimental research on micro hole drilling of polycrystalline Nd:YAG

Polycrystalline Nd:YAG materials have wide applications in solid-state lasers. In this study, micro hole drilling experiments were performed on polycrystalline Nd:YAG using a polycrystalline diamond micro drill. The hole diameter, edge chipping, and hole wall surface quality were examined in detail. The results showed that the hole diameter was slightly larger than tool diameter. A diameter error of less than 5.5% was achieved. The edge chipping at the entry hole was formed by the encircled petal shape exfoliations, which were produced by the indentation and rotation movement in the drilling entry stage. Edge chipping at the exit hole was generated by an entire piece of exfoliation, which was produced by a circle of microcracks around the tool tip propagating to the bottom surface in the drilling exit stage. The edge chipping width at the entry hole was smaller than that at the exit hole. Based on different material removal modes, the hole surface morphology was classified into three types: ductile removal, coexisting ductile and brittle removal, and brittle removal. The hole surface quality mainly depended on the proportion of the brittle fracture to ductile removal surface.     

Molecular Characteristics of Amyloid Precursor Protein (APP) and Its Effects in Cancer

Amyloid precursor protein (APP) is a type 1 transmembrane glycoprotein, and its homologs amyloid precursor-like protein 1 (APLP1) and amyloid precursor-like protein 2 (APLP2) are highly conserved in mammals. APP and APLP are known to be intimately involved in the pathogenesis and progression of Alzheimer’s disease and to play important roles in neuronal homeostasis and development and neural transmission. APP and APLP are also expressed in non-neuronal tissues and are overexpressed in cancer cells. Furthermore, research indicates they are involved in several cancers. In this review, we examine the biological characteristics of APP-related family members and their roles in cancer.     

Split Enzyme-Based Biosensors for Structural Characterization of Soluble and Insoluble β-Glucans

β-Glucan is widely distributed in various plants and microorganisms and is composed of β-1,3-linked d-glucose units. It may have a branched short or long side chain of glucose units with β-1,6- or β-1,4-linkage. Numerous studies have investigated different β-glucans and revealed their bioactivities. To understand the structure-function relationship of β-glucan, we constructed a split-luciferase complementation assay for the structural analysis of long-chain β-1,6-branched β-1,3-glucan. The N- and C-terminal fragments of luciferase from deep-sea shrimp were fused to insect-derived β-1,3-glucan recognition protein and fungal endo-β-1,6-glucanase (Neg1)-derived β-1,6-glucan recognition protein, respectively. In this approach, two β-glucan recognition proteins bound to β-glucan molecules come into close proximity, resulting in the assembly of the full-length reporter enzyme and induction of transient luciferase activity, indicative of the structure of β-glucan. To test the applicability of this assay, β-glucan and two β-glucan recognition proteins were mixed, resulting in an increase in the luminescence intensity in a β-1,3-glucan with a long polymer of β-1,6-glucan in a dose-dependent manner. This simple test also allows the monitoring of real-time changes in the side chain structure and serves as a convenient method to distinguish between β-1,3-glucan and long-chain β-1,6-branched β-1,3-glucan in various soluble and insoluble β-glucans.     

Structure,mechanical and thermal properties of Y-doped CrAlN coatings

CrAlYN coatings with different Y contents (0, 5 and 12 at.%) were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure, mechanical and thermal properties of CrAlN coatings by using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis and nanoindentation. The structural transformation of single phase cubic Cr_0.42Al_0.58N and Cr_0.39Al_0.56Y_0.05N coatings to cubic–wurtzite mixed Cr_0.32Al_0.56Y_0.12N coating leads to a drop in hardness from (30.2±0.7) GPa of Cr_0.42Al_0.58N and (32.0±1.0) GPa of Cr_0.39Al_0.56Y_0.05N to (25.2±0.7) GPa of Cr_0.32Al_0.56Y_0.12N. The incorporation of 5 at.% Y retards the thermal decomposition of CrAlN, verified by the postponed precipitation of w-AlN and N-loss upon annealing. Correspondingly, Cr_0.39Al_0.56Y_0.05N coating consistently exhibits the highest hardness value during thermal annealing. Nevertheless, alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN.     

Phase composition,microstructure and thermophysical properties of the Srx(Zr0.9Y0.05Yb0.05)O1.95+x ceramics

Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=1.0, 0.9, 0.8, 0.7) ceramics were prepared by solid state reaction sintering. The sintered Sr_1.0(Zr_0.9Y_0.05Yb_0.05)O_2.95 is a single-phase solid solution while the sintered Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=0.9?0.7) are composites, and a significant grain growth inhibition is observed in the sintered Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=1.0, 0.9). Rare-earth elements distribution in the bulk materials indicates that Yb and Y preferentially substitute Zr-sites in SrZrO₃, and the highest solubility of RE₂O₃ in pure SrZrO₃ is ～0.8 mol%. The sintered Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x have high thermal expansion coefficients up to ～11.0×10^?6 K^-1 (1200°C). Sr_0.8(Zr_0.9Y_0.05Yb_0.05)O_2.75 has the lowest thermal conductivity of 1.38 W·m^-1·K^-1 at 800°C. Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=1.0, 0.9, 0.8) show no phase transition from 600 to 1400°C, whereas Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=0.9, 0.8) have excellent high-temperature phase stability over the whole investigated temperature range. Therefore, Sr_x(Zr_0.9Y_0.05Yb_0.05)O_1.95+x (x=1.0, 0.9, 0.8) are considered as promising TBCs materials that might be operated at higher temperatures compared to YSZ.     

基于云网PoP的弹性边缘网络设计思路探讨

移动边缘云是公司“云+5G”双引擎战略的最佳契合点,边缘网络是发挥移动云“大云”产品和5G网络融合优势,实现云网统筹、构建运营商“连接+计算”核心能力的关键。运营商传统接入网存在云网割裂、分段入云和组网复杂等突出问题,难以适应边缘业务敏捷交付要求。本文通过深入分析边缘云业务特征和技术架构,对标业界主流云商建设实践,研究基于云网PoP网的边缘网络建设思路,创新性提出云网一体化规划设计和建设交付流程变革,基于云网POP统一网络和业务锚点,构建Overlay和Underlay融合双层加速网络架构,探索Spine-leaf化的新型城域接入网实现L3下沉和弹性扩容等方法,实现“云+网+应用”一体化敏捷交付的边缘网络能力。     

AP2M1 Supports TGF-β Signals to Promote Collagen Expression by Inhibiting Caveolin Expression

The extracellular matrix (ECM) is important for normal development and disease states, including inflammation and fibrosis. To understand the complex regulation of ECM, we performed a suppressor screening using Caenorhabditis elegans expressing the mutant ROL-6 collagen protein. One cuticle mutant has a mutation in dpy-23 that encodes the μ2 adaptin (AP2M1) of clathrin-associated protein complex II (AP-2). The subsequent suppressor screening for dpy-23 revealed the lon-2 mutation. LON-2 functions to regulate body size through negative regulation of the tumor growth factor-beta (TGF-β) signaling pathway responsible for ECM production. RNA-seq analysis showed a dominant change in the expression of collagen genes and cuticle components. We noted an increase in the cav-1 gene encoding caveolin-1, which functions in clathrin-independent endocytosis. By knockdown of cav-1, the reduced TGF-β signal was significantly restored in the dpy-23 mutant. In conclusion, the dpy-23 mutation upregulated cav-1 expression in the hypodermis, and increased CAV-1 resulted in a decrease of TβRI. Finally, the reduction of collagen expression including rol-6 by the reduced TGF-β signal influenced the cuticle formation of the dpy-23 mutant. These findings could help us to understand the complex process of ECM regulation in organism development and disease conditions.     

Recent Advances in Design of Functional Biocompatible Hydrogels for Bone Tissue Engineering

Bone related diseases have caused serious threats to human health owing to their complexity and specificity. Fortunately, owing to the unique 3D network structure with high aqueous content and functional properties, emerging hydrogels are regarded as one of the most promising candidates for bone tissue engineering, such as repairing cartilage injury, skull defect, and arthritis. Herein, various design strategies and synthesis methods (e.g., 3D-printing technology and nanoparticle composite strategy) are introduced to prepare implanted hydrogel scaffolds with tunable mechanical strength, favorable biocompatibility, and excellent bioactivity for applying in bone regeneration. Injectable hydrogels based on biocompatible materials (e.g., collagen, hyaluronic acid, chitosan, polyethylene glycol, etc.) possess many advantages in minimally invasive surgery, including adjustable physicochemical properties, filling irregular shapes of defect sites, and on-demand release drugs or growth factors in response to different stimuli (e.g., pH, temperature, redox, enzyme, light, magnetic, etc.). In addition, drug delivery systems based on micro/nanogels are discussed, and its numerous promising designs used in the application of bone diseases (e.g., rheumatoid arthritis, osteoarthritis, cartilage defect) are also briefed in this review. Particularly, several key factors of hydrogel scaffolds (e.g., mechanical property, pore size, and release behavior of active factors) that can induce bone tissue regeneration are also summarized in this review. It is anticipated that advanced approaches and innovative ideas of bioactive hydrogels will be exploited in the clinical field and increase the life quality of patients with the bone injury.     

承插型盘扣式支撑架在地铁车辆段工程中的应用

盘扣式支撑架具有承载力强、方便安全、结实耐用等优点,被广泛应用于地铁施工。本文以广州市轨道交通十八号线万顷沙车辆段为例,对承插型盘扣式支撑架在地铁车辆段工程中的具体应用进行了详细说明,以期为同类工程提供参考。