Sm3+掺杂的SnNb2O6粉体的光谱特性

采用熔盐法制备了Sm³⁺掺杂的SnNb₂O₆粉体, 利用X射线粉末衍射、扫描电子显微镜对其物相和形貌进行了表征, 用激发、发射光谱和荧光寿命对样品的发光性能进行了研究.结果表明:所得样品为单斜晶系的SnNb₂O₆, 在407 nm的激发下, 有较强的橙红色发射, 最强峰位于599 nm, 属于Sm³⁺的⁴G_5/2→⁶H_7/2跃迁.     

基于CuInS2/ZnS核壳结构量子点的高光效暖白光LED

采用逐步热注射法合成了用于白光LED的CuInS₂/ZnS(CIS/ZnS)核壳结构量子点.通过调整Cu/In的比率, 在CuInS₂(CIS)量子点的基础上, 合成了发射波长在570~650 nm之间可调的CIS/ZnS量子点.与CIS量子点的低量子产率相比, 具有核壳结构的CIS/ZnS量子点的量子产率达到了78%.通过在黄光荧光粉YAG :Ce³⁺表面旋涂CIS/ZnS量子点的方式制备了暖白光LED器件.在工作电流为10 mA时, 暖白光LED的发光效率达到了244.58 lm/W.由于CIS/ZnS量子点的加入, 所制备的白光LED器件的显色指数达到86.7且发光颜色向暖色调发生了转移, 相应的色坐标为(0.340 6, 0.369 0).     

催化剂的性质对超临界乙醇条件下热解木质素液化的影响

研究了在超临界乙醇中、氢气存在下,一系列金属-酸双功能催化剂的酸性、孔径大小、负载的金属对热解木质素加氢裂解过程的影响．制备并采用N₂等温吸附和BET比表面、X射线衍射、NH₃-程序升温脱附技术对催化剂进行表征．实验结果表明催化剂酸性增强可促进热解木质素的缩聚反应,从而产生大量的焦炭和水,导致其液化效率降低．微孔催化剂比介孔催化剂孔径小,与强酸共同作用会导致热解木质素裂解生成更多的小分子气体．在催化剂上负载金属Ru可有效地抑制热解木质素的缩聚反应,促进其裂解液化．     

Keggin‐Type Polyoxometalate‐Based Metal–Organic Networks for Photocatalytic Dye Degradation

The reaction of Keggin‐type polyoxometalate (POM) units, transition‐metal (TM) ions, and a rigid bis(imidazole) ligand (1,4‐bis(1‐imidazolyl)benzene (bimb)) in a hydrothermal environment led to the isolation of four new POM‐based metal–organic networks, [H₂L][CuL][SiW₁₂O₄₀]?2 H₂O ( 1 ), [H₂L]₂[Co(H₂O)₃L][SiW₁₁CoO₃₉]?6 H₂O ( 2 ), KH[CuL]₂[SiW₁₁CoO₃₉(H₂O)]?2 H₂O ( 3 ), and [CuL]₄[GeW₁₂O₄₀]?H₂O ( 4 ; L=bimb). All four compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compounds 1 and 3 are new 3D networks with 1D channels. Compounds 2 and 4 contain 2D networks, which further stack into 3D supramolecular networks. The contributions of pH value, the negative charge of the POM, and the TM coordination modes to the construction of 3D networks were elucidated by comparing the synthetic conditions and structures of compounds 1 – 4 . The photocatalytic properties of compounds 1 – 4 were investigated using methylene blue (MB) degradation under UV light. All compounds showed good catalytic activity and structural stability. The possible catalytic mechanism was discussed on the basis of active‐species trapping experiments. The different photocatalytic activities of compounds 1 – 4 were explained by comparison of the band gaps of different POM species and different packing modes of POM units in these hybrid compounds.     

Vertical vibrations of elastic foundation resting on saturated half-space

This paper is mainly concerned with the dynamic response of an elastic foun- dation of finite height bounded to the surface of a saturated half-space.The foundation is subjected to time-harmonic vertical loadings.First,the transform solutions for the governing equations of the saturated media are obtained.Then,based on the assumption that the contact between the foundation and the half-space is fully relaxed and the half- space is completely pervious or impervious,this dynamic mixed boundary-value problem can lead to dual integral equations,which can be further reduced to the Fredholm integral equations of the second kind and solved by numerical procedures.In the numerical exam- ples,the dynamic compliances,displacements and pore pressure are developed for a wide range of frequencies and material/geometrical properties of the saturated soil-foundation system.In most of the cases,the dynamic behavior of an elastic foundation resting on the saturated media significantly differs from that of a rigid disc on the saturated half-space. The solutions obtained can be used to study a variety of wave propagation problems and dynamic soil-structure interactions.     

A Proximal-Type Method for Convex Vector Optimization Problem in Banach Spaces

In this paper, we consider a convex vector optimization problem of finding weak Pareto optimal solutions from a uniformly convex and uniformly smooth Banach space to a real Banach space, with respect to the partial order induced by a closed, convex, and pointed cone with a nonempty interior. We introduce a vector-valued proximal-type method based on the Lyapunov functional, carry out convergent analysis on this method, and prove that any sequence generated by the method weakly converges to a weak Pareto optimal solution of the vector optimization problem under some mild conditions. Our results improve and generalize some known results.     

关于指数、Neuman-Sándor和二次平均的一个精确双向不等式

本文证明了双向不等式αI(a; b)+(1-α )Q(a; b) < M(a; b) < βI(a; b)+(1-β)Q(a; b) 对所有不相等的正实数a和b成立当且仅当α≥1/2 和β≤[e(√2log(1+√2)-1)]/[(√2e-2) log(1+√2)]=0:4121…,其中I(a; b), M(a; b)和Q(a; b)分别表示a和b的指数平均、Neuman-Sándor平均和二次平均.     

电解液阴极大气辉光放电原子发射光谱检测水硬度

在自制的电解液阴极大气辉光放电原子发射谱(ELCAD-AES)装置上,研究了钙镁标准溶液的特征发射光谱,定量检测了Mg和Ca的含量,两元素的检出限分别为0.2mg/L和0.8mg/L。通过准确性和加标回收实验,以及与乙二胺四乙酸二钠盐络合滴定(EDTA滴定)法测量结果的比较,证明了ELCAD-AES方法测量水硬度的可靠性。测定了沸腾前后的自来水和地下水,以及湖水中Mg和Ca的含量,获得了这些水样的硬度。所建立的ELCAD-AES方法可用于水体硬度或金属元素的快速在线监测。     

TiO_2纳米多孔薄膜漏模光波导共振传感器研究小分子的光谱灵敏度

在玻璃基片上溅射约50nm厚的金膜,在掺有P123聚合物的TiO2胶体溶液中浸渍提拉基片,经高温热处理后获得厚度约为210nm的TiO2纳米多孔薄膜。以此双层膜为漏模光波导芯片,并结合卤钨灯光源、CCD光谱仪、棱镜耦合器以及流动测试槽构建了基于Kretschmann结构的光谱测量式漏模光波导共振传感器。以非吸附型蔗糖水溶液为折射率液体,测试了传感器的折射率灵敏度。结果表明,在给定溶液折射率范围(1.3330～1.3557)内,漏模光波导共振波长随着折射率的升高而线形增大。以离子型表面活性剂和溴百里酚蓝为小分子吸附质,考察了传感器对小分子吸附的响应特性。结果表明,与只有一层金膜的SPR传感器相比,多孔薄膜漏模传感器对小分子吸附质的灵敏度大幅提高,这由于小分子在TiO2多孔薄膜导波层内的大量吸附。     

Crystallization process of lanthanum-substituted bismuth titanate synthesized by a facile sol–gel method

We present a facile sol–gel route to synthesize lanthanum-substituted bismuth titanate (BLT). The chemical reactions and crystallization process of this method using the initial materials of bismuth subnitrate [4BiNO₃(OH)₂·BiO(OH)], lanthanum nitrate [La(NO₃)₃·6H₂O] and tetrabutyl titanate [Ti(C₄H₉O)₄] were investigated by thermogravimetric and differential thermal analysis, IR spectroscopy, gas chromatography/mass spectrometry, Raman spectroscopy and XRD. The evaporation of the dissolved CO₂ in the amorphous BLT matrix is associated with the crystallization of BLT. The BLT gel is pure BLT perovskite when calcination temperature is higher than 500 °C. The grain size of the obtained nanoparticles ranges from 15 to 82 nm. The Arrhenius curve is obtained from the representation of the reduced sizes with respect to the calcination temperature. The activation energy of grain growth in BLT nanoparticles is 0.36 eV, which shows a rapidly growth process in the temperature range of 500–850 °C.