Ultrafast synthesis of near-infrared-emitting aqueous CdTe/CdS quantum dots with high fluorescence

The traditional aqueous route to synthesis CdTe/CdS Core/shell (c/s) quantum dots (QDs) via decomposition of Cd-thiol complexes is usually time consuming. Herein, an ultrafast and facile aqueous synthetic approach under atmospheric pressure for CdTe/CdS c/s QDs with emission from the green to the near-infrared window (535–820 nm) is reported. With purified CdTe core QDs diluted in solution of Cd-3-mercaptopropionic acid (MPA) complexes, CdTe/CdS c/s QDs with emission wavelengths at 700 and 800 nm can be obtained within 20- and 45-min refluxing under the optimized experimental conditions, respectively. This is the most rapid way to prepare CdTe/CdS c/s QDs in aqueous phase, and the obtained QDs were highly luminescent without postsynthesis treatment. The influences of various experimental factors, including Cd²⁺ concentration, MPA-to-Cd ratio, pH value, and dilution ratio on the growth rate and luminescent properties of the obtained CdTe/CdS c/s QDs, have been taken into consideration. The three processes “purification-dilution-addition” ensure the synthesis environment with high pH value and low core concentration and have a marked impact on the rapid synthesis rate and the resulting high fluorescence of CdTe/CdS c/s QDs.     

Selection of hydrogel electrolytes for flexible zinc–air batteries

Flexible zinc–air batteries attract more attention due to their high energy density, safety, environmental protection, and low cost. However, the traditional aqueous electrolyte has the disadvantages of leakage and water evaporation, which cannot meet application demand of flexible zinc–air batteries. Hydrogels possessing good conductivity and mechanical properties become a candidate as the electrolytes of flexible zinc–air batteries. In this work, advances in aspects of conductivity, mechanical toughness, environmental adaptability, and interfacial compatibility of hydrogel electrolytes for flexible zinc–air batteries are investigated. First, the additives to improve conductivity of hydrogel electrolytes are summarized. Second, the measures to enhance the mechanical properties of hydrogels are taken by way of structure optimization and composition modification. Third, the environmental adaptability of hydrogel electrolytes is listed in terms of temperature, humidity, and air composition. Fourth, the compatibility of electrolyte–electrode interface is discussed from physical properties of hydrogels. Finally, the prospect for development and application of hydrogels is put forward.     

Oxygen-vacancy-enhanced Catalytic Activity of Au@Co3O4/CeO2 Yolk-shell Nanocomposite to Electrochemically Detect Hydrogen Peroxide

Biomimetic electrochemical sensors are very promising not only due to their lower expense and longer stability than conventional enzymatic ones, but they also often suffer from simultaneously achieving high sensitivity and good selectivity. Here we present a well-defined Au@Co₃O₄/CeO₂ yolk-shell nanostructure (YSN) that is first synthesized and exploited as highly efficient electrocatalysts for hydrogen peroxide (H₂O₂) detection. The introduced CeO₂ in Co₃O₄ matrix greatly facilitates the migration of lattice oxygen, which increases the concentration of surface oxygen vacancies (O_a), remarkably enhancing the adsorption ability of H₂O₂ and promoting the decomposition of H₂O₂ for faster electron transfer than pristine Au@Co₃O₄ core-shell nanostructure (CSN). The abundant O_a of Au@Co₃O₄/CeO₂ YSN is confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The as-prepared biomimetic sensor delivers a wide dynamic range (5.0 nM to 5.4 μM), a low limit of detection (LOD) (2.74 nM), and a high sensitivity (35.67 μA μM⁻¹ cm⁻²), paving a new way to construct an ultrasensitive and selective enzyme-free biomimetic electrochemical sensor. Furthermore, the sensor is used to real-time monitor H₂O₂ released from human cervical cancer cells (HeLa) and human umbilical vein endothelial cells (HUVEC), demonstrating its great potential in practical applications.     

Sustainable Route for Synthesizing Aluminosilicate EU-1 Zeolite

Developing sustainable routes for the synthesis of zeolites is still a vital and challenging task in zeolite scientific community. One of the typical examples is sustainable synthesis of aluminosilicate EU-1 zeolite, which is not very efficient and environmental-unfriendly under hydrothermal condition due to the use of a large amount of water as solvent. Herein, we report a sustainable synthesis route for aluminosilicate EU-1 zeolite without the use of solvent for the first time. The physicochemical properties of the obtained EU-1 zeolite are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry-differential thermal analysis (TG-DTA), N₂ sorption, inductively coupled plasma (ICP) analysis, and solid nuclear magnetic resonance (NMR), which show the product has high crystallinity, uniform morphology, large BET surface area, and four-coordinated aluminum species. Moreover, the impact of synthesis conditions is investigated in detail. The sustainable synthesis of aluminosilicate EU-1 zeolite under solvent-free     

硅单粒子位移损伤多尺度模拟研究

本文结合分子动力学方法和动力学蒙特卡罗方法, 研究了单个粒子入射硅引起的位移损伤缺陷的产生和演化过程; 基于Shockley-Read-Hall理论计算了单个粒子入射引起的位移损伤缺陷导致的泄漏电流增加及其演化过程, 比较了缺陷退火因子与泄漏电流退火因子之间的差异, 并将计算结果与实验值进行了对比. 结果表明, 计算泄漏电流时, 仅考虑一种缺陷的情况下缺陷退火因子与泄漏电流退火因子相同, 考虑两种缺陷类型情况下二者在数值上有所区别, 但缺陷退火因子仍能在一定程度上反映泄漏电流的退火行为. 分子动力学模拟中采用Stillinger-Weber势函数和Tersoff势函数时缺陷退火因子和泄漏电流退火因子与实验结果一致, 基于Stillinger-Weber势函数的计算结果与实验值更为接近.     

紫外光辐照对TiO2纳米线电输运性能的影响及磁阻效应研究

采用溶胶凝胶法以及静电纺丝法, 利用热处理工艺, 成功制备出了多晶锐钛矿型TiO₂纳米线, 通过两线法在室温下测试单根TiO₂纳米线的V-I曲线来研究其电输运性能及磁阻效应. 结果表明: 在无光照环境下其V-I曲线为不过零点的直线, 零场电阻较大, 在磁场作用下电阻下降, 表现出负磁阻效应; 紫外光辐照环境下TiO₂纳米线载流子浓度增加使得电阻变小, 然而在磁场作用下电阻增大, 表现为正磁阻效应. 紫外光辐照导致的载流子浓度变化, 使得负磁阻转变为正磁阻, 我们将磁阻变化归结为d电子局域导致的负磁阻与能带劈裂导致的正磁阻两种机理相互竞争的结果.     

Detecting functional connectivity in the resting brain: a comparison between ICA and CCA

Independent component analysis (ICA) and cross-correlation analysis (CCA) are general tools for detecting resting-state functional connectivity. In this study, we jointly evaluated these two approaches based on simulated data and in vivo functional magnetic resonance imaging data acquired from 10 resting healthy subjects. The influence of the number of independent components (maps) on the results of ICA was investigated. The influence of the selection of the seeds on the results of CCA was also examined. Our results reveal that significant differences between these two approaches exist. The performance of ICA is superior as compared with that of CCA; in addition, the performance of ICA is not significantly affected by structured noise over a relatively large range. The results of ICA could be affected by the number of independent components if this number is too small, however. Converting the spatially independent maps of ICA into z maps for thresholding tends to overestimate the false-positive rate. However, the overestimation is not very severe and may be acceptable in most cases. The results of CCA are dependent on seeds location. Seeds selected based on different criteria will significantly affect connectivity maps.     

酰胺连接的共价有机骨架的制备及其在水中高效光催化性能

光催化是将太阳能转换为化学能的绿色可持续发展途径,有望解决日益严重的能源危机和环境污染问题.在光催化过程中,半导体材料作为光催化剂,负责可见光的捕获、光生载流子的生成和传输以及氧化还原反应,在整个光催化系统中起着决定性的作用.共价有机骨架材料(COFs)是一类新兴的半导体光催化剂,已被证明在可见光诱导的水分解、二氧化碳还原、有机转化反应和水中污染物降解方面具有应用前景.然而,大部分COFs是通过可逆反应构筑的,在水中及苛刻条件下的稳定性差.因此,提升基于COFs的光催化剂在水相中的光催化活性和循环稳定性仍然面临巨大挑战.本文提出了一种新策略,即通过实现多重协同效应,设计和开发2D-COFs作为在水中的高效非均相光催化剂.通过后合成策略将亚胺键连接的2D-COFs氧化,制备了两种具有丰富三嗪结构单元的以酰胺键连接的2D-COFs(命名为COF-JLU18和COF-JLU19).结果表明,COF-JLU18和COF-JLU19具有高比表面积和孔体积,其比表面积分别为1156和541 m2/g;COF-JLU19具有比相似拓扑结构的亚胺COF-JLU17更好的水蒸气吸附性能.此外,COF-JLU19表现出了极高的化学稳定性,在水中、盐酸和氢氧化钠溶液中浸泡两天,其结构和结晶性均没有发生明显变化.由此可见,酰胺键不仅可以增加材料骨架的亲水性,还能够提高COFs对水的稳定性.本文制备的酰胺键连接的COF-JLU19材料,在光降解罗丹明B水溶液(RhB)反应中可以获得高达0.69 min?1的光降解速率常数,活性明显优于其他光催化剂,如C3N4等.COF-JLU19具有较好的催化活性主要归因于以下两方面:一方面,良好的亲水性和固有孔隙率之间的协同效应可以增强COFs在水中对染料的吸附能力,使其光催化活性得到有效提升;另一方面,高的结晶度和优秀的稳定性使酰胺键连接的COFs在多相光催化中实现稳定循环利用.为了扩展COFs的应用前景,本文还制备了一种基于酰胺键连接COFs的静电纺丝膜,在以太阳光为光源的光降解罗丹明B水溶液实验中表现出较高的光催化活性和重复使用性.综上,本文提出的多重协同效应为基于COFs的高效光催化剂的设计提供了一种有效策略.     

A ratiometric near-infrared naphthalimide-based fluorescent probe with high sensitivity for detecting Fe2+ in vivo

Iron is one of the essential trace elements in the human body. It plays an important role in human biology and pathology. Deregulation of iron levels in cells is associated with disease development. In this work, we synthesized a novel near-infrared intramolecular charge transfer (ICT) based ratiometric fluorescent probe to detect Fe²⁺, by using naphthalimide and indole moieties as building blocks. Our work showed that the radiometric probe has excellent selectivity, sensitivity and rapid response. Moreover, we could successfully perform real-time monitoring of Fe²⁺ in HeLa cells and C. elegans.