Highly efficient removal of U(VI) in aqueous solutions by tea waste-derived biochar-supported iron-manganese oxide composite

Journal of Radioanalytical and Nuclear Chemistry - Uranium-containing wastewater poses a major threat to human health because of its toxicity and radioactivity. To address this issue, tea...     

Microporous regenerated cellulose-based macrogels for covalent immobilization of enzymes

Cellulose - In this study, regenerated cellulose-based macrogels with abundant carboxyl groups and interconnected microporous structures were synthesized from cellulose fibers (CFs)/cellulose...     

Polyaniline/oxidation etching graphitic carbon nitride composites for U(VI) removal from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - Polyaniline/oxidation etching g-C3N4 composites (PANI/OCN) were synthesized through an oxidative polymerization method and applied to remove...     

Recent advances in catalytic automotive emission control: Passive NO storage at low temperatures

In the practical applications, a high portion of the NO_x is emitted without purification in the cold start period of engine because the selective catalytic reduction (SCR) or NO_x storage and reduction (NSR) catalysts are not warmed up. Passive NO_x absorbers (PNA) were proposed earlier to store the NO_x at low temperatures and release the stored NO_x during warm-up period when the SCR and NSR catalysts downstream are functional, while this concept just attracted great interests recently to meet the extra stringent requirement of governmental emissions regulations. A plant of PNA catalysts, showing different NO adsorption/release characteristics, was disclosed. This review summarizes the recent progress in the development of PNA catalysts. The characteristics of NO adsorption/release on precious metal (i.e., Pt, Pd) loading Al₂O₃ support catalysts, CeO₂ support catalysts, and zeolite support catalysts are summarized and compared.     

Unusual Through-Space Interactions between Oxygen Atoms that Mediate Inverse Morphochromism of an AIE Luminogen

We have studied the photophysics of tetrafurylethene, an aggregation-induced emission luminogen with exceptionally short intramolecular O−O distances of 2.80 Å and a significant red-shifted morphochromism (27 nm) when going from the aggregate to the crystal. The short O−O distances, which are substantially smaller than the sum of the van der Waals radii (3.04 Å), are due to the fact that the oxygen atoms act as an electronic bridge connecting the furan rings on opposite ends of the central double bond, giving rise to a circular delocalization of the π-electron density across the rings. In the excited state the O−O distance is further reduced to 2.70 Å; the increased O−O interaction causes a narrowing of the HOMO–LUMO gap, resulting in the red morphochromism of the emission. Our results show the structural origin of the red-shifted emission lies in close O−O contacts, paving the way for understanding the clusteroluminescence of oxygen-rich non-conjugated systems that emit visible light.     

Nanosheets of Ni-SAPO-34 Molecular Sieve for Selective Oxidation of Cyclohexanone to Adipic Acid

Nanosheets of nickel doped SAPO-34 molecular sieves in thickness of ∼10 nm (denoted as NS−Ni-SAPO-34) has been successfully prepared through a morphology-reserved method of synthesis. A special aluminum phosphate in two-dimensional layered structure is used as precursor and converts to crystallized SAPO-34 molecular sieve, in nanosheet morphology reserved from the aluminum phosphate precursor, under hydrothermal conditions with tetraethyl orthosilicate and templates of mixed amines added. It is found that adequate amount of nickel, ∼5 wt %, added to the synthetic system is a key factor for the morphology-reserved synthesis. By characterization, the nickel is proved to be doped in the framework of the molecular sieve, which more likely helps to balance the high surface energy of nanosheet products. The NS−Ni-SAPO-34 shows excellent catalytic performance for oxidation of cyclohexanone to adipic acid by gaseous oxygen.     

封闭渔场收入优化的捕捞规划模型

运用定量的手段,对封闭渔场可获最大净收入现值的捕捞规划问题进行了分析,建立了制定捕捞规划的理论模型,并给出了模型中参数的具体计算方法。     

缺陷与催化

催化技术在现代工业生产和日常生活中发挥着举足轻重的作用,开发高效的催化剂是催化领域重要的研究方向。近些年来,许多研究发现催化剂的缺陷对其催化活性有着重要的影响,同时各种各样的缺陷催化剂也被开发出来。尽管如此,缺陷与催化活性之间的关系仍有待厘清。本文围绕这一主题,分别介绍了固体缺陷化学的基础、催化剂中缺陷的类型、表征、可控构筑以及在催化中的作用和动态变化,最后进行总结和展望。希望通过本文阐明催化剂缺陷化学研究的起源与发展,强调缺陷对催化的重要性,为今后高效催化剂的进一步开发与机理研究提供指导。