Simultaneous analysis of six inorganic anions in urine by double-suppress ion-exchange chromatography

This study is aimed to establish a simple, rapid, and accurate ion chromatography approach for the simultaneous detection of six inorganic anions in urine. Various performance parameters affecting the determination of anions were optimized, including the selection of sample protein precipitation agent, eluent, and flow rate. The final eluent was 3.6 mmol/L sodium carbonate and 12% isopropanol with a flow rate of 0.6 mL/min. Acetonitrile was used for pretreatment to precipitate proteins, and the volume ratio of urine to acetonitrile was 1:4. The correlation coefficient of the target anion calibration curve ranged from 0.9973 to 0.9999. The limit of detection ranged from 1.50 to 12.0 μg/L, and the method detection limit ranged from 15.0 to 120 μg/L. The standard recovery rate for low, medium, and high concentrations ranged from 90 to 110%. The inter-day and intra-day relative standard deviations were <5%. The method has high accuracy and good reproducibility and is suitable for the separation and determination of anions in urine.     

Kinetically rate-determining step modulation by metal—support interactions for CO oxidation on Pt/CeO2

Science China Chemistry - Rational design and performance promotion are eternal topics and ultimate goals in catalyst preparation. In contrast, trial—and—error is still the common...     

CuS nanodots-loaded biohybrid magnetic helical microrobots with enhanced photothermal performance

Magnetic helical microrobots swimming at low Reynolds numbers have attracted much interest because of their great potentials for biomedical applications. However, to endow them with sophisticated function integration toward targeted disease treatment still remains a major challenge. Here, we proposed a novel strategy of using Spirulina scaffolds to fabricate biohybrid magnetic helical microrobot (BMHM) with enhanced photothermal performance to fight against cancer cells and pathogenic bacteria. For the first time, CuS nanodots were densely and uniformly loaded intracellularly inside Spirulina cells after permeabilization, and Fe₃O₄ nanoparticles were subsequently deposited on the cell walls for magnetization. The BMHMs could be actuated forward at a high velocity and flexibly steered under rotating magnetic fields. Rapid and great photothermal temperature raise with robust cycling stability was achieved under 808 nm near-infrared laser irradiation. The BMHMs showed good biocompatibility with minor toxicity to HeLa cancer cells and Escherichia coli bacteria. Moreover, significant photothermal performance was further verified via a series of experiments for anticancer therapy and bacteria killing. Because of the remarkable features and facile cost-effective fabrication, the BMHMs demonstrated great potentials as an integrated microrobot platform for future anticancer and antibacteria applications.     

Interaction of Hydrogen with Ceria: Hydroxylation,Reduction, and Hydride Formation on the Surface and in the Bulk

The study reports the first attempt to address the interplay between surface and bulk in hydride formation in ceria (CeO₂) by combining experiment, using surface sensitive and bulk sensitive spectroscopic techniques on the two sample systems, i.e., CeO₂(111) thin films and CeO₂ powders, and theoretical calculations of CeO₂(111) surfaces with oxygen vacancies (O_v) at the surface and in the bulk. We show that, on a stoichiometric CeO₂(111) surface, H₂ dissociates and forms surface hydroxyls (OH). On the pre-reduced CeO_2−x samples, both films and powders, hydroxyls and hydrides (Ce−H) are formed on the surface as well as in the bulk, accompanied by the Ce³⁺ ↔ Ce⁴⁺ redox reaction. As the O_v concentration increases, hydroxyl is destabilized and hydride becomes more stable. Surface hydroxyl is more stable than bulk hydroxyl, whereas bulk hydride is more stable than surface hydride. The surface hydride formation is the kinetically favorable process at relatively low temperatures, and the resulting surface hydride may diffuse into the bulk region and be stabilized therein. At higher temperatures, surface hydroxyls can react to produce water and create additional oxygen vacancies, increasing its concentration, which controls the H₂/CeO₂ interaction. The results demonstrate a large diversity of reaction pathways, which have to be taken into account for better understanding of reactivity of ceria-based catalysts in a hydrogen-rich atmosphere.     

多相催化过硫酸盐工艺处理水环境中有机污染物的非自由基过程

20世纪80年代至今,水处理技术中的高级氧化过程(AOP)已被广泛研究及应用。然而水体中的有机污染物仍因种类繁多和降解难易不同困扰着研究者们,因此对于AOP的机理过程需要更深入的分析认识,以利于技术的进一步发展及应用。AOP中的过硫酸盐氧化工艺近年来得到大量关注,其自由基机理的关键活性物种是·OH 和·SO₄^-。非自由基机理分为¹O₂氧化和PS直接氧化(也称电子转移),某些体系中高价态金属也直接或间接地参与氧化过程。但非自由基过程的发生机理及优势特点仍存在争议。本文综述了基于多相催化过硫酸盐高级氧化过程处理水中有机污染物的最新研究,阐述反应机理及其分析手段,并指出当前研究可能存在的问题。对于过硫酸盐高级氧化工艺中非自由基过程的未来研究方向及应用前景提出展望。     

石榴石固体电解质Li3BO3界面改性研究

石榴石固体电解质由于其高的离子电导率,对锂金属稳定等优点成为了下一代高性能锂电池的重要研究方向之一。但锂金属负极界面浸润性与锂枝晶问题限制了其应用。本文通过简单的液相沉积结合高温烧结的方法,在石榴石固体电解质片表面构建了一层稳定的硼酸三锂(Li₃BO₃)修饰层。研究表明,Li₃BO₃修饰层可以有效改善石榴石固体电解质与锂金属负极界面接触,促进锂的均匀沉积/溶出,从而抑制锂枝晶生长,提高界面稳定性。Li₃BO₃修饰后石榴石电解质片与锂金属之间紧密结合,Li/石榴石界面阻抗由修饰前的1780 Ω·cm²降低至58 Ω·cm²。得益于界面接触的改善,Li₃BO₃修饰后的LLZTO电解质组装的对称电池可以在0.1 m·cm^-2的电流密度下稳定工作超过700 h。而未修饰的对称电池在0.05 mA·cm^-2的电流密度下短时间工作即出现微短路现象。     

Six-step synthesis of Leonurine and toxicity study on zebrafish

Leonurine (1), an important ingredient in leonurus sibiricus L., can be used for some gynecological disease. We have developed a concise and efficient synthetic route of Leonurine, which can be optimized for mass production. Commercially available compound 6 and 2,3-dihydrofuran (7) were used as starting materials. And the toxicity study on zebrafish shows that Leonurine would promote the hatching of zebrafish embryos at low concentration and result in acute death or chronic lethal toxicity at high concentration.     

Absorption,transportation and distribution of imidacloprid in maize

The neonicotinoid imidacloprid is a very important insecticide in maize cultivation in China. A laboratory experiment was conducted to investigate its absorption, transportation and distribution in maize plants. Plants were exposed to an aqueous solution of imidacloprid at five concentrations (10, 20, 50, 100 and 200 μg/mL). The residues of imidacloprid in different plant parts were determined by using a quick and effective method of high-performance liquid chromatography. Results showed that the average recoveries ranged from 85.16% to 102.23%, with relative standard deviations of 1.82–4.40% at three different spiking levels in each different matrix. The half-lives of imidacloprid in hydroponic maize water were from 5.33 to 11.55 days. The concentrations in roots, stems and leaves were from 5.61 to 7.48, 1.03 to 4.03 and 0 to 30.57 μg/mL after 6 h–7 days exposed in 10 μg/mL imidacloprid aqueous solutions, respectively. Our study showed that imidacloprid was strongly absorbed by roots and mainly accumulated in leaves. Quantity ratio and bioconcentration factors (BCFs) were also used to estimate the distribution and accumulation in maize. The values of quantity ratios were the highest in the leaves while lowest in the root after 7 days treatments, with the ranking of leaves > stem > root. The BCFs were 0.63–1.66, 0.52–0.92 and 3.20–6.78 in root, stem and leaves, respectively. These results demonstrated that the exposed time and imidacloprid application concentrations were also the main factors influencing the absorption. This study enhances our understandings of the uptake and distribution of imidacloprid in maize plants.     

Mechanistic study of Ce-modified MnO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/TiO<Subscript>2</Subscript> catalysts with high NH<Subscript>3</Subscript>-SCR performance and SO<Subscript>2</Subscript> resistance at low temperatures

A series of Ce–MnO _x /TiO₂ catalysts were prepared using a novel sol–gel template method and investigated for low-temperature selective catalytic reduction (SCR) of NO with NH₃ at temperatures ranging from 353 to 473 K. The 0.07Ce–MnO _x /TiO₂ catalyst showed the highest activity and best resistance to SO₂ poisoning. The structure and properties of the catalysts were characterized using X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), thermogravimetry (TG)–differential scanning calorimetry (DSC)–mass spectroscopy (MS), high-resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) measurements, H₂-temperature-programmed reduction (TPR), and NH₃-temperature-programmed desorption (TPD). The superior catalytic activity of the 0.07Ce–MnO _x /TiO₂ catalyst was probably due to a change in the active components, an increase in surface active oxygen and surface acid sites, and lower crystallinity and larger surface area with Ce doping. Furthermore, the reduction ability also became stronger. The SO₂ poisoning resistance of the 0.07Ce–MnO _x /TiO₂ catalyst improved because doping with Ce can effectively decrease the formation of ammonium salt on the catalyst surface and the sulfation of MnO _x . In situ diffuse-reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments indicated that addition of Ce could promote adsorption of NH₃ and inhibit generation of some nitryl species. The SCR reactions over the catalysts mainly followed the Eley–Rideal mechanism accompanied with a partial Langmuir–Hinshelwood mechanism.     

含季鏻阳离子的[Mo6O19]2-多酸化合物的合成、结构及光催化性能研究

通过使用季鏻盐与钼酸铵在常温条件下合成了含季鏻阳离子的(n-PentylPh₃P)₂[Mo₆O₁₉]多酸化合物,并通过X-射线单晶衍射、红外光谱、紫外光谱、热重分析和电化学对其进行了表征。产物中的季鏻配体上的氢原子通过与多酸阴离子端基氧原子形成氢键而构筑了一维链状结构,并且季鏻配体上的苯环与相邻季鏻配体上的苯环通过π-π作用形成三维层状结构。此外,对该多酸化合物的光催化降解亚甲基蓝的性能进行了研究。