Influences of gallium substitution on the phase stability,mechanical strength and cellular response of β-tricalcium phosphate bioceramics

β-tricalcium phosphate (β-TCP), a well-accepted synthetic bone grafting biomaterial, is confronted with limitations of poor phase stability and lacking the capacity to mediate the biological functions. In the current study, gallium (Ga) was substituted for calcium in the β-TCP, and the influences of Ga substitution on the phase stability, compressive strength and cellular response of β-TCP bioceramics were investigated. The results indicated that substitution of at least 2.5 mol% Ga for calcium prevented the β-TCP from transforming into α-TCP at 1250 °C. The β-TCP bioceramics substituted with 2.5 mol% Ga attained the highest compressive strength. The β-TCP bioceramics substituted with 2.5 and 5 mol% Ga showed good cytocompatibility, and suppressed in vitro osteoclastic activity as well as osteoblastic differentiation. Considering the favorable mechanical strength and the inhibitory effect on the osteoclastic activity, the β-TCP bioceramics substituted with 2.5 mol% Ga are promising for treating the bone defect in the pathological state of excessively rapid bone resorption.     

Preparation of biphasic hydroxyapatite/ β-tricalcium phosphate foam using the replication technique

Biphasic hydroxyapatite/β-tricalcium phosphate foams were prepared using the replication technique starting from a precipitated hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂: HAP) powder, and sodium glycerophosphate (GP). The effect of the grinding time, solid loading, dispersant amount, and etching, replication, and sintering processes were investigated. The SEM, OEM and FTIR analyses proved that the surface of the polyurethane template must be treated with NaOH solution to make it more hydrophilic prior to the coating process. With a solid loading of 40 wt-%, the slurries prepared from the precipitated hydroxyapatite presented a shear thinning behavior, which was useful for the coating process. The SEM analysis of the foams showed that the optimum number of coating layers to obtain foam with an identical structure with the template was limited to three. The use of GP and the optimized preparation parameters helped to decrease the consolidation temperature of the ceramic foams to 1000 °C. The XRD and FTIR analyses of the prepared foams showed that the thermal treatment of the GP and the HAP mixture led to a partial decomposition of the HAP to tricalcium phosphate. The fitting of the XRD patterns and the obtained lattice parameters proved that the decomposition was accompanied by the insertion of sodium from GP toward the lattice of tricalcium phosphate and the formation of Na-β-tricalcium. The results of the SEM analysis, the pore size distribution and the mechanical strength showed that the presence of the Na-β-tricalcium reduced the pore size distribution from 500-2700 to 100–1700 μm, decreased slightly the total porosity from 80 vol-% to 70 vol-%; and improved the mechanical strength of the obtained foam from 1.56 MPa to 2.60 MPa.     

Visible emission and energy transfer in Tb3+/Dy3+ co-doped phosphate glasses

In this work, we systematically study the spectroscopic properties of Tb³⁺/Dy³⁺ co-doped phosphate glasses in the visible spectral region and explore the sensitization role of Dy³⁺ in the enhancement of visible fluorescence of Tb³⁺ ions. Judd-Ofelt parameters Ω₂ and Ω₄/Ω₆ of the phosphate glass as host for Tb³⁺ are calculated as 21.60 × 10^-20 cm² and 0.73, respectively, based on the measured spectral absorption. Multiple energy transfer (ET) routes from Dy³⁺ to Tb³⁺ and their efficiencies are characterized, and the enhanced fluorescence properties of Tb³⁺ are investigated, including the emission spectral strength and the spontaneous emission lifetime as functions of Dy³⁺ doping concentration. The efficient nonradiative ET processes between Dy³⁺ and Tb³⁺ allow a moderate concentration level of Tb³⁺ to achieve favorably stronger spectral absorption at blue and ultraviolet wavelengths. Tb³⁺/Dy³⁺ co-doped phosphate glass shows promising potential for phosphors and lasing operation at visible wavelengths.     

不同粒径改性粉煤灰对磷酸根吸附性能的影响

废水排放过量的磷导致水体污染日益严重,将粉煤灰通过化学改性制备成了水化硅酸钙吸附剂,研究了改性吸附剂对磷酸根的吸附效果。利用XRD, SEM及BET比表面积等手段对粒度分级前后的吸附剂进行表征,研究不同粒级吸附剂对磷酸根的吸附性能,并考察其吸附机理。结果表明,不同粒级的吸附剂其化学成分出现了明显的偏析现象,孔隙结构也差异显著。相比其他粒径下的吸附剂颗粒,颗粒粒径在50?75 μm时,吸附剂中钙和硅含量较多,铝、铁和镁含量较低,水化硅酸钙组分含量最高,且伴有含铝的托贝莫来石晶体出现,钙离子的增加使其可以与更多的磷酸根结合形成沉淀。同时此粒径下具有较高的比表面积及孔隙度,疏松多孔的结构为钙离子提供更多活性位点。当使用粒径在50?75 μm的吸附剂吸附磷酸根时,磷的饱和吸附量可达到17.1 mg/g,比未分级的吸附剂高19.58%。     

The Modification of Chrome Tanned Leather by Polyethylene Glycol-Linked Gemini Fatty Alcohol Phosphate

A series of polyethylene glycol-linked Gemini fatty alcohol phosphate surfactants (GFAP) were prepared with long chain n-alkanol (C = 8, 12, 16, 18), polyethylene glycol (PEG-200, PEG-400, PEG-600, PEG-800, PEG-1000) and phosphorus oxychloride (POCl₃). The structure of the prepared surfactants was characterized by Fourier transform infrared spectrometer (FT-IR). The surfactants were employed for the modification of chrome-tanned leather. The morphological changes of chrome-tanned leather and modified chrome-tanned leather were observed by scanning electron microscopy (SEM). The relationship between the alkyl chain length and molecular weight of the PEG and the hydrophobicity, softness, mechanical strength of modified chrome-tanned leather was also discussed. The experimental results showed that the mechanical strength and softness of modified chrome-tanned leather were enhanced with an increase of alkyl chain length, while the hydrophobicity, mechanical strength and softness were decreased with an increase of molecular weight of the PEG. The hydrophobicity, mechanical strength and softness of modified chrome-tanned leather were optimized for an alkyl chain length of 16. Therefore, 16–200 Gemini phosphate surfactants with an alkyl chain length of 16 and a PEG molecular weight of 200 have a good comprehensive modification effect on Chrome-tanned leather, the tensile strength, tear strength and softness of modified chrome-tanned leather are 57.07 N mm⁻², 79.49 N mm⁻¹, 9.73 mm, respectively.     

采场围岩变形与破坏监测技术研究进展及展望

深部煤炭资源开发面临更多复杂、多变、高难的开采地质问题,采场围岩形态结构是矿井安全生产的重要评价指标之一,开展采场围岩变形与破坏测是判别矿井隐蔽致灾地质问题的重要技术保障。在煤炭工业快速发展的近20余年时间里,围岩体形变监测技术取得了长足的进步,基于矿山采场围岩体变形与破坏的影响因素,按照监测形式对监测技术进行了划分,归纳了当前用于矿山采场围岩变形与破坏监测的钻孔测试技术、地球物理探测技术、光纤监测技术及其他测量技术及其特点,结合煤层顶底板、巷道两帮空间监测的工程应用实例,介绍了不同监测技术的主要进展、优缺点以及适用性,讨论了探测技术的革新趋势和未来矿井安全生产中采场围岩变形与破坏监测技术的发展方向。同时,也认识到现有监测技术虽然已取得显著的监测效果,但是仍不能够满足矿井现代化、智能化生产需要。对于监测技术的进步而言,既需要技术装备的不断优化,更是要跨学科、跨专业科学技术理论的完善与更新。在当前地学大数据、云计算、人工智能新一轮科技创新基础上,今后采场围岩变形与破坏的监测技术必然向多元化、多参数、智慧化、全程监控的方向发展,监测方式也将不断地向可视化、动态化的监测预警模式过渡,融合监测技术发挥多参数的作用将越来越重要。     

高应力区沿空留巷围岩现状监测研究与分析

陈四楼矿计划实施沿空留巷的2802运输巷,断层较多,直接顶厚度较大,巷道矿压显现较为明显。针对顶板下沉、两帮外鼓、顶板淋水较大、巷道顶板受压破碎、金属网锈蚀严重、压脱锚杆较多、两帮位移较大等现象,提出在高应力区采用矿压监测的方法,通过对巷道变形现状进行的监测分析,对巷道破坏变形程度有了清晰的认识,对造成巷道破坏变形原因和影响因素有了详细的分析,根据注浆加固可改善围岩结构,提高围岩承载能力及锚杆、锚索锚固性能,是一种较为有效的围岩控制措施,确定了需要采用注浆加固的方式对进行巷道围岩破坏变形治理,并根据现场实际情况对注浆材料的性能提出了要求。     

深埋巷道围岩变形及支护技术研究

随着煤炭开采逐渐向深部转移,巷道围岩变形越来越严重。分析了深埋巷道围岩变形及支护技术,对研究巷道进行了三轴抗拉试验,得到煤和岩石力学参数,采用结构梁和弹性力学分析了巷道围岩变形,为模型分析提供了理论基础,然后采用FLAC^3D数值模拟软件,分析了巷道变形位移,与现场实测相比,数值模拟能够较好地模拟煤矿巷道实际变形情况。研究能够为巷道参数设计提供借鉴。     

深部软岩巷道围岩变形特征及数值模拟分析

针对深部煤矿开采条件下软岩巷道围岩出现持续流变时间长、变形大、地压高、巷道难以维护等特点,首先分析了深部软岩巷道变形特征,采用FLAC^3D数值模拟软件,分析了不同埋深条件下巷道围岩垂直应力分布、水平应力分布以及巷道围岩塑性区扩展规律。研究得出,深部软岩巷道的围岩岩块呈松散破碎形态,相互翻转和滑移,岩体的模量和强度低;随着巷道埋深的逐渐增加,巷道围岩应力集中系数逐渐减小,巷道垂直、水平应力峰值逐渐变大,塑性破坏范围扩展速率逐渐增加。研究为深部软岩巷道支护提供理论基础。     

三软煤层沿空留巷矿压显现规律研究

为探究沿空留巷矿压显现规律及支护对策,以河南西部典型三软煤层为研究对象,构建了数值分析模型,模拟了工作面前方和后方一定范围内巷道围岩变形和应力变化规律,得到了工作面后方围岩受采动影响大、范围广,顶板下沉现象明显。基于现场实测,得到了顶板下沉量、底板鼓起量、充填体的变形、实煤体变形等随采动影响的变化规律,监测了锚杆的轴向受载情况。研究发现,巷旁膏体充填与巷道内高强锚杆+W型钢带构成的支护体系,较好地解决了三软煤层回采巷道围岩控制问题,为类似开采条件下沿空留巷的实施提供了理论和实践依据。