Remarkable nanosize effect of zirconia in Au/ZrO2 catalyst for CO oxidation

Nanosize effect of ZrO2 in Au/ZrO2 catalyst was studied by deposition-precipitation of Au nanoparticles in similar sizes (4-5 nm) on ZrO2 nanoparticles of varying sizes. The catalysts were characterized with XRD, TEM, XPS, and nitrogen adsorption to understand the effect of ZrO2 particle size on the catalytic nanostructures. Nanocomposite Au/ZrO2 catalysts consisting of comparably sized Au-metal (4-5 nm) and ZrO2 (5-15 nm) nanoparticles are found advantageous over those containing similarly sized Au-metal but larger ZrO2 (40-200 nm) particles for CO oxidation. This finding may have important implications on the designed preparation of advanced nanostructured catalysts and other chemical materials.     

载紫杉醇星型M-PLA-TPGS纳米颗粒的合成及其用于前列腺癌治疗药物载体的研究

合成了一种甘露醇引发的星型共聚物甘露醇-聚乳酸-聚乙三醇1000维生素E琥珀酸酯(M-PLATPGS).利用纳米沉淀法制备载紫杉醇M-PLA-TPGS纳米颗粒.纳米颗粒近似球形,粒径分布较窄.对载药纳米颗粒进行粒径、表面电荷、载药量、包封率和体外药物释放的表征,结果表明,体外药物释放呈双相释放模型,M-PLA-TPGS纳米颗粒在前列腺癌PC-3细胞中的摄取水平要高于PLGA和PLA-TPGS纳米颗粒.载紫杉醇M-PLA-TPGS纳米颗粒对于前列腺癌细胞的的毒性显著高于载紫杉醇PLA-TPGS纳米颗粒和商业制剂Taxol,证明星型M-PLA-TPGS聚合物作为纳米药物载体优于线性PLGA和PLA-TPGS聚合物.     

A Diazido Mannose Analogue as a Chemoenzymatic Synthon for Synthesizing Di‐N‐acetyllegionaminic Acid‐Containing Glycosides

A chemoenzymatic synthon was designed to expand the scope of the chemoenzymatic synthesis of carbohydrates. The synthon was enzymatically converted into carbohydrate analogues, which were readily derivatized chemically to produce the desired targets. The strategy is demonstrated for the synthesis of glycosides containing 7,9‐di‐N‐acetyllegionaminic acid (Leg5,7Ac₂), a bacterial nonulosonic acid (NulO) analogue of sialic acid. A versatile library of α2‐3/6‐linked Leg5,7Ac₂‐glycosides was built by using chemically synthesized 2,4‐diazido‐2,4,6‐trideoxymannose as a chemoenzymatic synthon for highly efficient one‐pot multienzyme (OPME) sialylation followed by downstream chemical conversion of the azido groups into acetamido groups. The syntheses required 10 steps from commercially available d ‐fucose and had an overall yield of 34–52 %, thus representing a significant improvement over previous methods. Free Leg5,7Ac₂ monosaccharide was also synthesized by a sialic acid aldolase‐catalyzed reaction.     

Photocatalytic Hydrogen Production Coupled with Selective Benzylamine Oxidation over MOF Composites

Photocatalytic water splitting requires separation of the mixed H₂ and O₂ products and is often hampered by the sluggish O₂‐producing half reaction. An approach is now reported to address these issues by coupling the H₂‐producing half reaction with value‐added benzylamine oxidation reaction using metal–organic framework (MOF) composites. Upon MOF photoexcitation, the electrons rapidly reduce the protons to generate H₂ and the holes promote considerable benzylamine oxidation to N‐benzylbenzaldimine with high selectivity. Further experimental characterizations and theoretical calculation reveal that the highly conjugated s‐triazine strut in the MOF structure is crucial to the efficient charge separation and excellent photocatalytic activity.     

A Multi‐signal Fluorescent Probe with Multiple Binding Sites for Simultaneous Sensing of Cysteine,Homocysteine, and Glutathione

A novel fluorescent probe was developed by integrating chlorinated coumarin and benzothiazolylacetonitrile and exploited for simultaneous detection of cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). Featuring four binding sites and different reaction mechanisms for different biothiols, this probe exhibited rapid fluorescence turn‐on for distinguishing Cys, Hcy, and GSH with 108‐, 128‐, 30‐fold fluorescence increases at 457, 559, 529 nm, respectively, across different excitation wavelengths. Furthermore, the probe was successfully applied to the fluorescence imaging of endogenous Cys and GSH and exogenous Cys, Hcy, and GSH in living cells.     

Selective Hydrogenation of CO2 to Ethanol over Cobalt Catalysts

Methods for the hydrogenation of CO₂ into valuable chemicals are in great demand but their development is still challenging. Herein, we report the selective hydrogenation of CO₂ into ethanol over non‐noble cobalt catalysts (CoAlO_x), presenting a significant advance for the conversion of CO₂ into ethanol as the major product. By adjusting the composition of the catalysts through the use of different prereduction temperatures, the efficiency of CO₂ to ethanol hydrogenation was optimized; the catalyst reduced at 600 ° gave an ethanol selectivity of 92.1 % at 140 °C with an ethanol time yield of 0.444 mmol g^?1 h^?1. Operando FT‐IR spectroscopy revealed that the high ethanol selectivity over the CoAlO_x catalyst might be due to the formation of acetate from formate by insertion of *CH_x, a key intermediate in the production of ethanol by CO₂ hydrogenation.     

Eosin Y as a Direct Hydrogen‐Atom Transfer Photocatalyst for the Functionalization of C−H Bonds

Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom transfer catalyst for C?H activation. Using the alkylation of C?H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C?H bonds in a green and sustainable manner.     

From Metal–Organic Frameworks to Single‐Atom Fe Implanted N‐doped Porous Carbons: Efficient Oxygen Reduction in Both Alkaline and Acidic Media

It remains highly desired but a great challenge to achieve atomically dispersed metals in high loadings for efficient catalysis. Now porphyrinic metal–organic frameworks (MOFs) have been synthesized based on a novel mixed‐ligand strategy to afford high‐content (1.76 wt %) single‐atom (SA) iron‐implanted N‐doped porous carbon (Fe_SA‐N‐C) via pyrolysis. Thanks to the single‐atom Fe sites, hierarchical pores, oriented mesochannels and high conductivity, the optimized Fe_SA‐N‐C exhibits excellent oxygen reduction activity and stability, surpassing almost all non‐noble‐metal catalysts and state‐of‐the‐art Pt/C, in both alkaline and more challenging acidic media. More far‐reaching, this MOF‐based mixed‐ligand strategy opens a novel avenue to the precise fabrication of efficient single‐atom catalysts.     

Stress‐Transfer‐Induced In Situ Formation of Ultrathin Nickel Phosphide Nanosheets for Efficient Hydrogen Evolution

Ultrathin two‐dimensional (2D) nanostructures have attracted increasing research interest for energy storage and conversion. However, tackling the key problem of lattice mismatch inducing the instability of ulreathin nanostructures during phase transformations is still a critical challenge. Herein, we describe a facile and scalable strategy for the growth of ultrathin nickel phosphide (Ni₂P) nanosheets (NSs) with exposed (001) facets. We show that single‐layer functionalized graphene with residual oxygen‐containing groups and a large lateral size contributes to reducing the lattice strain during phosphorization. The resulting nanostructure exhibits remarkable hydrogen evolution activity and good stability under alkaline conditions.     

生物修复技术在重金属污染治理中的应用

随着工业的发展，重金属对环境的污染越来越引起人们的关注。生物修复技术以其投资少、效率高、可以原位修复低浓度有害污染物的特性而在环境污染治理中发挥了巨大的作用，自上世纪80年代产生以来，得到了越来越广泛的应用。本文简要介绍了几种生物修复技术在污染治理中的应用，以期进一步推动重金属污染的治理和修复工作。