Self-activated persistent luminescence from Ba2Zr2Si3O12 for information storage

Till now, many doped persistent luminescence (PersL) phosphors have been investigated and found various applications in such as bioimaging, photocatalysis and information storage, but introducing PersL emitters into a proper host is mostly complex. In this research, a self-activated PersL phosphor Ba₂Zr₂Si₃O₁₂ (BZSO) is prepared by solid state reaction. By adding NH₄Cl, the self-activated PersL intensity is evidently enhanced. The trap depths and concentrations are examined by thermoluminescence spectra. Meanwhile, Bi³⁺ ions are introduced into BZSO and show wide band photoluminescence (PL) from 300 to 600 nm. Moreover, the PL of Bi³⁺ is tunable under excitation by 265-350 nm lights. Furthermore, as a proof-of-concept design, we designed a patterned quick response (QR) code based on the self-activated PersL of BZSO, and the information of “South China University of Technology (SCUT)” can be read out by the code scanning technology. Bi³⁺-doped BZSO phosphors are suggested to provide potential applications in information storage by its self-activated PersL, and to excite researchers to study the tunable PL in Bi³⁺-doped phosphor.     

New insight into the formation and oxygen barrier mechanism of carbonaceous oxide interlayer in a multicomponent carbide

Early transition metal carbides are considered to be superior candidate materials for oxidizing environments at temperatures exceeding 2000°C. Generally, the remarkable oxidation resistance is largely attributed to a carbonaceous oxide interlayer (eg, Hf–O–C, Zr–O–C, and Ta–O–C), located at the interface between the external oxide layer and internal carbide (eg, HfC, ZrC, and TaC), acting as the primary oxygen barrier. However, the oxygen barrier mechanism of the carbonaceous oxide interlayer remains unclear. Herein, through studying the oxidation behavior of a novel multicomponent carbide Hf_0.5Zr_0.3Ti_0.2C in oxidizing environments up to 2500°C, the oxygen barrier mechanism of the carbonaceous oxide was recently revealed. We found that the oxygen barrier resulted from the slow oxygen diffusion through the inner grains of Hf-Zr–Ti–O due to the presence of carbon formed at the grain boundaries because of the existence of compact external oxide layer, beneath which the Hf–Zr–Ti–O–C interlayer possesses much lower oxygen activity and temperature that allow carbon to exist stably. This as-formed carbon strongly retarded the fast diffusion of oxygen along the grain boundaries of oxides. Additionally, desirable synergisms of the designed multicomponent system, particularly, the outward short-circuit diffusion of Ti, lead to the self-healing of the external oxide layer, evidently enhancing integral protection performance against oxidizing environments.     

Synergistic effects of modified TiO2/multifunctionalized graphene oxide nanosheets as functional hybrid nanofiller in enhancing the interface compatibility of PLA/starch nanocomposites

The aim of this study is to investigate the synergistic effects of modified TiO₂/multifunctionalized graphene oxide nanosheets at different ratios on the interface compatibility between starch and poly(lactic acid) (PLA). To this end, silanylated nano-TiO₂ (MTiO₂, 1 and 2%) and alkylated maleic anhydride grafted graphene oxide (f-GO, 0.1, 0.2, and 0.4%) at different combinations are blended with the PLA-starch composites using solution blending technique. Then, the synergistic effects of MTiO₂ and f-GO on PLA/starch matrix are investigated in terms of the morphology, crystallinity, structural characterization, thermal stability, dynamic mechanical, and antiaging properties, and the related mechanisms. The Raman and Fourier transform infrared spectroscopy spectra verify the successful synthesis of the two modified nanofillers (f-GO and MTiO₂) and the formation of strong hydrogen bond within the PLA-starch nanocomposites. Due to the strong interfacial interaction and the synergistic effect from the combination of 1% MTiO₂ and 0.2% f-GO, obvious improvement was observed in PLA-starch versus other nanocomposites in terms of morphology, thermal stability, surface hydrophobicity, storage modulus, ultraviolet-shielding capacity, and aging-resistance. Furthermore, differential scanning calorimeter (DSC), isothermal crystallization kinetic, and X-ray diffraction analysis demonstrate that f-GO and the M-TiO₂ significantly synergize in enhancing the crystallization rate and crystallinity of PLA/starch matrix. These results provide novel insights for constructing high-performance nanocomposites and facilitate their applications in food packaging.     

基于Galerkin法弱形式的时间积分法

从加权残差法的角度出发,利用Galerkin法的弱形式建立了一种高精度的隐式时间积分法。在时间单元上用拉格朗日插值函数构造近似解。给出了使用线性、二次和三次插值函数构造的积分格式,它们的精度依次为二阶、四阶和六阶。求解时首先消去时间单元内部的未知量,有效地提高了计算效率。通过减缩积分,可将条件稳定的格式变为无条件稳定的格式。数值算例表明该方法的精度和效率明显高于Newmark法。     

一种具有蛋白酶活力的配合物的合成与表征

本文以氨三乙酸与乙二胺的酰胺化合反应得到的三(乙二胺酰乙基)胺(NTE)作为配体,与Zn(Ⅱ)配位得到一种新的具有蛋白酶活力的配合物Zn(NTE).(ClO4)2。采用元素分析、红外光谱及差热-热重分析手段对该配合物的组成与结构进行了表征。该配合物的蛋白酶活力为7.48U/mg,比文献报道的成功的水解酶模型物三(2-苯并咪唑亚甲基)—锌(Ⅱ)配合物的蛋白酶活力高62%。     

低温透明微粉抛光砖的变形原因及其解决方法

本文分析了窑炉控制过程中低温透明微粉抛光砖产生变形的原因并介绍了其预防措施。     

bauma China 2006——筑造商机——展会回顾

2006年11月21日,秋雨连绵的上海,第三届中国国际工程机械、建材机械、工程车辆与设备博览会在上海新国际博览中心隆重举行开幕仪式。国际工程机械万商云集,两年一次的盛会使上海滩再次聚焦全球工程机械生产商、采购商的目光。德国联邦经济技术部国务秘书Bernd Pfaffenbach先生、中国机械工业联合会执行副会长朱森第先生、德国慕尼黑国际博览集团主席兼首席执行官Manfred Wutzlhofer先生、上海市浦东新区常务副区长万大宁先生、德国机械设备制造业联合会工程机械和建材协会会长Christof Kemmann博士等出席了开幕式。德国慕尼黑国际博览集团主席兼首席执行官胡明峰先生、bauma China中方合作单位代表中国国际贸易促进委员会机械行业分会会长孙喜田先生、中国工程机械工业协会理事长韩学松先生等分别致词。他们表示,作为中国市场中工程机械、建筑与建材行业内最成功、最重要的博览会,bauma China2006在展会规模、展商数量、产品展示、展会服务等都是盛况空前的,充分体现了国际展会的特色和服务理念。     

超高压线路工频电场超限值对策的研究

针对日益增多的超高压线路引起的环境问题,研究了超高压线路工频电场超限值对策。通过对现有的和采用屏蔽措施后的地面电场强度分布、屋顶场强分布分别进行仿真计算分析和模拟试验,确定出架设屏蔽线和接地围栏两种屏蔽方案;根据屏蔽方案在现场采取屏蔽措施,在500kV线路下边相外架设1根屏蔽线,高度11m,水平距离距边相2m,试验结果表明屏蔽后场场强降低了35%。     

磁流变液的流体动力学理论

在外加磁场作用下,磁流变液从牛顿流体变成了Bingham体,超过屈服应力开始流动,其的流变性(弹性、塑性、粘性)、磁化性、导电性、传热性以及其它的机械性质和物理学性质皆发生显著的改变.研究磁流变液在外加磁场作用下,流场分布规律随磁场强度变化的动态特性,建立磁流变液的流体动力学理论,对开发和设计磁流变器械至关重要.本文运用物理学和流体力学的基本理论,结合本构方程,考虑磁场对磁流变液的流动的影响,建立了磁流变液力磁耦合的流体动力学模型,给出了描述磁流变液流动的基本方程组.     

磁流变阻尼器管道流动特性研究

磁流变阻尼器是一种应用广泛的磁流变器件,其利用磁流变液独特的磁流变效应的工作.然而,磁流变体阻尼器设计中,一般地将磁流变液作为粘性流体建立流动的力学模型,进行流动分析以及参数设计,这样设计的结果与实测出现了较大的误差.本文将磁流变体作为一种粘塑性流体,建立了描述磁流变液流动的力学场和电磁场耦合的流体动力学基本方程组,分析研究了磁流变阻尼器沿狭长管道流动的特征,为磁流变阻尼器的设计提供了可靠的理论基础.