A Titanium and Tantalum Phosphate LiNaTiTa2P2O13 with An Open Framework hosting Li and Na Ions

Herein, we report a detailed structural, electric, thermal and optical analysis of a titanium and tantalum phosphate LiNaTiTa₂P₂O₁₃. The title compound is comprised of typical ReO₃-type layers constituted by corner-sharing TiO₆ and TaO₆ octahedra, bridged by PO₄ tetrahedra, and the structure is closely related to monophosphate niobium bronzes. The existence of pentagonal tunnels, hosting the Li⁺ and Na⁺ ions, endows LiNaTiTa₂P₂O₁₃ a moderate ion transportation behavior (4.67×10⁻⁴ S/cm at 823 K). In addition, the successful substitution of Nb for Ta in LiNaTiTa₂P₂O₁₃ results in the optical absorption red-shift towards visible range with a narrowing band gap, which may provide a route of isomorphic replacement to band engineering for photo-catalysis.     

Wet and Functional Adhesives from One-Step Aqueous Self-Assembly of Natural Amino Acids and Polyoxometalates

Sessile organisms have undergone long-term evolution to develop the unique ability by positioning themselves on wet solid surface through secreting adhesive proteins. The present study reveals that natural amino acid monomers can also exhibit similar adhesion capacity. This kind of biomimetic adhesives were created by the one-step aqueous assembly of basic amino acids with assistance of anionic polyoxometalates. The polyoxometalates not only serve as multivalent scaffold to initiate the supramolecular cross-linking of amino acid molecules, but also function as a redox component, bestowing the wet adhesives with electrochromic features.     

Tetrahedron

Connecting a triangle base and an apex forms a simplest polyhedron—that is, a tetrahedron. On account of their structural simplicity and stability, two common classes of tetrahedra—namely, M₄L₄ and M₄L₆ (M indicates anions or metal cations, L indicates ligands with C₃ symmetry for M₄L₄ and C₂ symmetry for M₄L₆, respectively)—can be readily constructed from (i) six straight edges through an edge‐bridged strategy or (ii) four triangle faces through a face‐capped strategy, by means of supramolecular or coordination assembly. The intrinsic cavities inside tetrahedra enable them to act as versatile hosts for encapsulating a variety of guests, which leads to a wide range of applications including molecular recognition, catalysis, sensing and so on. In this review, we intend to summarize specifically the work carried out in the realm of porous tetrahedral cages. It includes representative synthetic strategies for the preparation of tetrahedra along with a general summary on their structural features. Thereafter, we will highlight the state‐of‐the‐art progress in various functions of tetrahedra, in addition to presenting a full overview of applications wherein we aim to provide new insights into the design and preparation of new topological geometric structures and functional materials on the basis of the simplest polyhedron—tetrahedron.     

Comparative studies on electrochemical activity of graphene nanosheets and carbon nanotubes

This study compares the electrochemical activity of four kinds of carbon materials, i.e. single-walled carbon nanotubes (SWNTs), pristine graphene oxide nanosheets (GONs), chemically reduced GONs, and electrochemically reduced GONs, with potassium ferricyanide (K₃Fe(CN)₆), β-nicotinamide adenine dinucleotide (NADH) and ascorbic acid (AA) as the redox probes. Cyclic voltammetry (CV) results demonstrate that the electron transfer kinetics of the redox probes employed here at the carbon materials essentially depend on the kind of the materials, of which the redox processes of the probes at SWNTs and electrochemically reduced GONs are faster than those at the pristine and chemically reduced GONs. The different electron transfer kinetics for the redox probes at the carbon materials studied here could be possibly ascribed to the synergetic effects of the surface chemistry (e.g., C/O ratio, presence of quinone-like groups, surface charge, and surface cleanness) and conductivity of the materials. This study could be potentially useful for understanding the structure/property relationship of the carbon materials and, based on this, for screening and synthesizing advanced carbon materials for electrochemical applications.     

An improved method for analyzing chlormequat and mepiquat in source waters by solid-phase extraction and liquid chromatography-mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method for the identification and quantification of chlormequat (CQ) and mepiquat (MQ) in source waters with high sensitivity and specificity was established using WCX cartridges (150 mg/6 mL) for pre-concentration of the samples and using the CAPCELL PAK CR 1:4 (2.0 mm × 150 mm 5 μm, SCX:C18 = 1:4) column containing strong cationic exchange resins and C18 for separation. The method could solve the problem for pre-concentrating ionic compounds from water samples and avoid the MS instrument fouling problem accompanied with the use of ion-pair reagents. After the optimization of analytical conditions, quantification was achieved in the positive electrospray ionization mode using selected ion monitoring. The samples were analyzed with multi-channel mode with quantification performed at 30 V cone voltage to ascertain the sensitivity and qualitative analysis performed at 60 V cone voltage simultaneously. The method detection limits (MDLs) of CQ and MQ in source water were determined to be 14 and 22 ng L⁻¹. Finally, the method was used to quantify CQ and MQ in several source waters, which gave a level ranging from below the quantitation limit to 28 ng L⁻¹.     

Determination of telmisartan in rat tissues by in-tube solid-phase microextraction coupled to high performance liquid chromatography

A poly(methacrylic acid-ethylene glycol dimethacrylate, MAA-EGDMA) monolithic capillary was used for the direct and on-line extraction of telmisartan from Sprague-Dawley rat tissue (heart, kidney, and liver) homogenates. Under optimized conditions, the tissue homogenates were simply diluted with a mixture of phosphate buffer (pH 2)/ACN (90:8 v/v), and then injected for extraction only after centrifugation and filtration. Coupled to HPLC with fluorescence detection, the method was linear over the range of 1.25-1500 ng/g for telmisartan in heart and kidney, 12.5-15 000 ng/g in liver with correlation coefficients over 0.9992. The detection limits were found to be in the range from 0.24 to 1.8 ng/g. RSDs for intra- and inter-day ranged from 1.2 to 8.1%. The determination of telmisartan in treated rat tissues was achieved by using the proposed method.     

Study on the Formation Mechanism of Nanotube TiO2

Nanotube TiO2 is a novel kind of nanomaterials. In 1998, Kasuga et al. first found that the nanotube TiO2 can be obtained through the treatment of the powered polycrystalline TiO2 in concentrated NaOH solution1. Then, we studied its morphological structure and physicochemical properties, and the results reported elsewhere2(Fig. 1, cover of Chinese Science Bulletin). In this paper the formation mechanism of nanotube TiO2 will be discussed.     

应用复振幅滤波器实现高斯光束均匀化

激光束的光强分布为高斯分布。在激光应用的许多领域，要求光束的光强为均匀分布。本文提出了一种利用复滤波器实现高斯光束均匀化的新方法。给出了复滤波器的制作方法和实验结果。实验表明，该方法是一种能量转化率较高、容易实现、均匀化程度较为理想的高斯光束均匀化的方法。     

叶蜡石高温高压相变的荧光光谱研究

 对合成金刚石过程中，叶蜡石经高温高压淬火后的不同部位进行了研究。发现叶蜡石的两条荧光线14 428 cm^-1和14 398 cm^-1在高温和高压作用下均发生蓝移，温度压力共同作用比温度压力分别作用时两峰的蓝移明显减小。通过合成金刚石的温度、压力条件的共同作用，仅在靠近合成样品位置的叶蜡石发生了相变。本文认为造成蓝移的原因是温度压力的作用使电子能级或成键电子能级发生改变。