Electrochromic Detection of Latent Fingermarks on Metal Surface Using 1,1′-Dibenzyl-4,4′-bipyridinium Dichloride

The electrochromic detection of latent fingermarks on polished or unpolished, flat or curved metal surfaces is described using electrochromic material, 1,1’-dibenzyl-4,4’-bipyridinium dichloride. The surface area covered by fingermarks acts as an insulating mask, causing 1,1’-dibenzyl-4,4’-bipyridinium dichloride to change color and produce inversed images of the fingermark. By changing the applied potential, the optical properties of 1,1’-dibenzyl-4,4’-bipyridinium dichloride can be continuously and reversibly adjusted to optimize the visual contrast of fingermarks, so as to realize the detection of latent fingermarks on stainless steel surface. It is demonstrated that the fabricated electrochromic devices can detect the fingermarks on these types of surfaces within twenty seconds at −1.0∼−2.0 V. This work can qualify as a tangible improvement in fingermark detection of the natural fingermarks on the never-cleaned (more than 3 years) and curved surfaces of daily-used container, e. g. cup, and the handle of cleaning tool, mop.     

Preparation of Fe−Co−LDH/MXene modified electrode for sensitive determination of arsenic (III) in aquatic system

3-dimensional (3D) Fe−Co−LDH/MXene composite was synthesized by in-situ synthesis and assembly of Fe−Co−LDH rod around MXene under hydrothermal condition. Due to the unique 3D configuration and good conductivity, the obtained Fe−Co−LDH/MXene modified glassy carbon electrode (Fe−Co−LDH/MXene/GCE) showed excellent electrochemical activity for As(III) detection. Via square-wave anodic stripping voltammetry, the response current on Fe−Co−LDH/MXene/GCE had good linear relationship with As(III) concentrations (1∼1000 ppt) with superior sensitivity (0.22 μA ppt⁻¹ cm⁻²) and low detection limit (0.9 ppt). The mechanism of As(III) adsorption was demonstrated. The electrode showed excellent anti-interference ability. Real water sample analysis demonstrated the Fe−Co−LDH/MXene/GCE was deployable in aqua-system.     

Synthesis and characterization of new homologue multinary selenides,M2Sb5Bi5Se17 (M = Sn,Pb)

New quaternary selenides M₂Sb₅Bi₅Se₁₇ (M = Sn, Pb) were synthesized using solid-state sintering reactions that crystallize in the monoclinic system with C2/m (No. 12) space group with lattice parameters a = 27.914(7) Å, b = 4.0804(11) Å, c = 15.512(4) Å, and β = 114.881(9)° for M = Sn, and a = 27.987(3) Å, b = 4.1062(5) Å, c = 15.6372(19) Å, and β = 115.318(3)° for M = Pb, respectively. The crystal structure is related to a homologous series [A⁺²_2x−4B⁺³₄ Se⁻²_2x−2][B⁺³_2y−2Se⁻²_3y−3] with (x, y) = (3, 4) that contains building units of two-dimensional slabs of NaCl¹¹¹-type [Sb₂Bi₄Se₁₁] separated by 1D ribbons NaCl¹⁰⁰-type [Pb₂Sb₃BiSe₆]. The NaCl¹¹¹ unit contains edge-shared octahedra filled with Sb³⁺ and Bi³⁺ cations, which are parallel and overlapped to form a step-layer 2D network stacking alone [001]. The NaCl¹⁰⁰ type ribbons containing Pb²⁺ and Sb³⁺ in square or trigonal pyramidal environments with the general formula [M₆Se₆] filled in the space between 2D layers of NaCl¹¹¹ units. The conductivity measurement revealed semiconducting property with band gaps of ~0.1 eV. Pb₂Sb₅Bi₅Se₁₇ exhibits low thermal conductivity 3,000 μW cm⁻¹ K⁻¹ in a temperature range of 300–480 K.     

SAPO－5，－11和－34分子筛模板剂的脱除及其结构的热致变化

用水热法合成了ＳＡＰＯ－５,－１１和－３４硅磷酸铝类分子筛。并对经不同温度焙烧处理的样品进行表征,结果表明：分子筛中模块剂的热分解过程与其结构和孔大小有较大的关系。在ＳＡＰＯ－５和ＳＡＰＯ－３４分子筛中,外部联接的Ｔ－Ｏ－Ｔ键的反对称伸缩振动峰（１２４０ｃｍ~（－１）－１０３８ｃｍ~（－１））和其对称伸缩振动（７３４ｃｍ~（－１）－６００ｃｍ~（－１））及双环的变形振动（６００－５００ｃｍ~（－１））的吸收峰对样品的结晶度比较敏感。但在ＳＡＰＯ－１１中,分子筛骨架中Ｔ－Ｏ－Ｔ反对称伸缩振动（１２２５ｃｍ~（－１）和１０３８ｃｍ~（－１））随结晶度的下降而基本保持不变,但内四面体（ＴＯ_４）的对称伸缩振动,反对称伸缩振动峰及Ｔ－Ｏ弯曲振动峰随样品焙烧温度的升高而减弱并分裂。红外吸收带向低频方向移动。ＳＥＭ－ＥＤＡＸ结果表明：随样品焙烧温度的升高,结晶度下降,分子筛晶形变得不规则,晶面越来越粗糙,但结晶度的下降并非由于其中ＰＯ_４四面体的热分解所引起,而是由外部联结的Ｔ－Ｏ－Ｔ键的断裂,双环被破坏及骨架元素间的重排所引起。     

α-松油烯-马来酸酐加成物的气相色谱分析

气相色谱法直接测定α－松油佛－马来酸酐加成物，不但免去了容量滴定法测定时必先分离共存马来酸酐的繁琐手续，而且方法简便、快速，能满足合成过程中跟踪分析的需要。