Designing lanthanide-doped nanocrystals with both up- and down-conversion luminescence for anti-counterfeiting

The widespread forgery in all kinds of paper documents and certificates has become a real threat to society. Traditional fluorescent anti-counterfeiting materials generally exhibit unicolor display and suffer greatly from substitution, thus leading to a poor anti-counterfeiting effect. In this work, unseen but significant enhanced blue down-conversion emission from oleic acid-stabilized lanthanide-doped fluoride nanocrystals is first present and the mechanism is proposed and validated. This not only endows these nanocrystals with dual-mode fluorescence, but also offers a simplified synthesis approach for dual-mode fluorescent nanocrystals involving no further complicated assembly or coating procedures, unlike the traditional methods. Furthermore, by changing the host/dopant combination or the content of dopant, these nanocrystals can exhibit simultaneously multicolor up-conversion emission under excitation at near-infrared light and unalterable blue down-conversion emission under ultraviolet light. A preliminary investigation of their anti-counterfeiting performance has been made, and the results indicate that this color tuning capability and high concealment makes these nanocrystals behave in a similar way to chameleons and can provide a strengthened and more reliable anti-counterfeiting effect.     

Large scale and environmentally friendly preparation of micro-submicron spherical silica and their surface effect in resin materials

Amorphous micro-submicron spherical silica powders with different particle sizes and surface properties were prepared by turbulent flow cycle method and characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MASS), X-ray diffraction (XRD), particle size distribution (PSD), specific surface area (SSA) analysis and scanning electron microscopy (SEM). The effects of particle size and surface property of different spherical silica on the fluidity of resin materials were conducted. The result showed that the spherical silica with the characterization of D₅₀ = 2.5 μm and the ratio of experimental specific surface area and calculated specific surface area is 2.38, played a better role in the flow ability of epoxy materials. So it may be a better choice for the preparation of epoxy materials used in IC packaging area and other high-tech fields.     

钛酸盐功能陶瓷的研究进展

钛酸盐陶瓷具有优良的电学、光学、化学特性,尤其在电学方面,表现出介电性、压电性、铁电性和热释电效应等,被广泛用于电子、能源、环保行业。笔者介绍了钛酸盐陶瓷的结构、制备技术、典型化合物及其在电学方面的应用。     

媒体信息技术在中小学体育教学中的运用

随着我国教育体制改革的不断进步,各大中小学在各个学科的教学过程中也取得了重要的成就。中小学阶段作为整个人生教育的初级阶段,对学生的今后成长和发展具有重要的影响。伴随着媒体信息技术的发展为我国中小学的教学提供了多种多样的教学工具。体育课程的开设对中小学生的体质塑造和发展发挥了重要的作用。因此,笔者在文中针对我国中小学阶段体育教学中存在的问题进行了简单地阐述,并对媒体信息技术在教学中的优势以及应用进行了详细地探讨,希望为我国中小学体育教学提供一定的指导意义和借鉴意义。     

物联网在国土资源管理中的研究与应用

随着信息技术的不断发展,物联网逐渐成为各行各业实现智慧管理的重要手段之一.以物联网概念以及国土资源管理的内容为基础,深入分析了物联网技术在国土资源管理领域的应用方法和重要内容,给出了智慧国土信息决策平台的总体设计思路、体系架构和建设内容,旨在为智慧国土的发展提供方向,提升国土资源科学化管理水平与监管效能.     

A new Pb(Lu1/2Nb1/2)O3–PbZrO3–PbTiO3 ternary solid solution with morphotropic region and high Curie temperature

A ceramic ternary system of (1?x?y)Pb(Lu_1/2Nb_1/2)O₃–xPbZrO₃–yPbTiO₃ (PLuN–PZ–PT) has been prepared by two-step synthetic process and characterized by X-ray powder diffraction and electric measurements. A morphotropic phase boundary (MPB) region has been delimited in the ternary system at room temperature. With the PLuN content increasing, the morphotropic phase boundary region becomes broad as well as the dielectric peak. The best comprehensive piezoelectric properties were achieved at MPB composition 0.42PLuN–0.1PZ–0.48PT, with the piezoelectric coefficients d₃₃, the Curie temperature T_c, the planar electromechanical coupling factor K_p, and the remnant polarizations P_r being 367 pC/N, 360 °С, 68% and 35 μС/cm², respectively. The results indicate that the PLuN–PZ–PT ternary ferroelectric material may be a promising candidate for high-power electromechanical transducers that can operate in a large temperature range.     

回流比对前置BAF系统除氮和除DEHP的影响

前置反硝化生物活性滤池(BAF)工艺是目前污水脱氮的常用工艺,但该工艺去除邻苯二甲酸二(2-乙基己基)酯(DEHP)的研究未见报道。为此,利用实验室小试装置,对前置反硝化BAF工艺去除DEHP的性能进行了评价并重点研究了硝酸盐回流比的影响。结果表明,系统进水DEHP为100μg/L左右时,该工艺的DEHP平均去除率在55%左右。其中,前置反硝化BAF的DEHP平均去除率在30%左右,硝化BAF的DEHP平均去除率在20%左右。兼氧条件更有利于DEHP的去除。硝酸盐回流比从100%改变为300%后,整个工艺对DEHP的去除率变化不大,但总氮的去除率变化较大。这说明DEHP降解菌和硝化、反硝化细菌对环境的要求不同,生态位也可能不同。综合考虑DEHP和总氮的去除,该套系统的最佳体积回流比为200%。     

Chemical Compatibility between Boron Oxides and Electrolyte and Cathode Materials of Solid Oxide Fuel Cells

Boron is a key component in glass and glass–ceramic sealants for planar solid oxide fuel cells (SOFCs). In this paper, the chemical compatibility between boron and commonly used electrolyte and cathode materials of SOFCs such as Y_0.16Zr_0.84O₂ (YSZ), Gd_0.1Ce_0.9O₂ (GDC), La_0.8Sr_0.2MnO₃ (LSM), La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF), SrCo_0.2Fe_0.8O₃ (SCF), and (Ba,Sr)(Co,Fe)O₃ (BSCF) are studied. The oxide couples with 43 wt.% H₃BO₃ (equivalent to 30 wt.% B₂O₃) were heat‐treated at 600–800 °C in air for 20 h. XRD analysis shows that the selected electrolyte and electrode materials are not chemically compatible with boron at temperatures above 600 °C. YSZ and GDC react with boron, forming YBO₃ and GdBO₃, respectively. In the case of LSM, LSCF, and BSCF powders, the chemical reaction with boron causes the disintegration and decomposition of the perovskite structures. Boron shows a higher reactivity with La₂O₃ as compared with SrO. On the other hand, the chemical reaction is substantially reduced between volatile boron species and dense electrolyte pellets, but porous electrolyte scaffolds are more susceptible by boron attack as compared to dense electrolyte pellets. The present study suggests that the direct contact between the volatile boron species and electrolyte and cathode materials should be avoided to minimize the detrimental damage of the boron poisoning on the stability and durability of SOFCs.     

激光烧蚀R-T不稳定性研究中的双模式CH平面调制靶制备

为研究同一次激光驱动下初始扰动幅值不同时瑞利-泰勒（Rayleigh-Taylor,R-T）不稳定性非线性演化的差别,采用单点金刚石车削技术,以太空铝合金为材料加工了两侧具有不同扰动幅度的模板。然后利用旋转涂覆工艺将模板表面的扰动图形转移至CH薄膜表面,制得了双模式CH平面调制靶。通过QC-5000型光学显微镜、alpha-step 500型台阶仪、NT1100型白光干涉仪等对铝合金模板及CH平面调制靶的周期、振幅等参数进行测量。结果表明：模板和CH平面调制靶的两侧均具有不同的扰动图形;两侧扰动的波长相同,均为54 μm左右,但振幅不同,分别为4.8 μm和1.9 μm;两侧扰动的平衡位置在同一水平面,调制图形的各项参数与设计值基本一致,模板表面的扰动图形成功地转移到了CH薄膜表面,获得了满足R-T不稳定性实验需求的双模CH平面调制靶。     

试论金矿文化的创新发展

联系金矿实际,分析了金矿文化的产生、目前存在问题及创新发展的意义,提出了以人为本、讲求实效、突出特色、追求卓越、系统运作等举措,对金矿文化的创新发展具有较好的借鉴和参考指导价值。