Influence of Fe-doping on the microstructure and electromagnetic performance of manganese oxides

A simple wet chemical method was used to synthesize Fe-doped MnO₂ composites with iron amount ranging from 0 to 90 M percent. X-ray diffraction, electron probe micro-analyzer, scanning electron microscopy and vector network analyzer were employed to investigate the effect of iron doping on the microstructure and electromagnetic performance of the as-synthesized samples. Results indicate that relative small content of Fe-doping cannot change the α-MnO₂ structure but can promote the formation of hollow-structural morphology. The as-obtained products are transformed into a novel compound (Fe_0.67Mn_0.33)OOH with the increase of Fe-doping to 30 mol%. The possible formation mechanism was proposed in detail. Compared with the pure MnO₂, the Fe-doped samples exhibit decreased dielectric loss but increased magnetic loss with increasing the iron content below 20 mol% while relatively poor electromagnetic properties with the iron content above 30 mol%.     

低温燃烧法制备Mn-CeO_x催化剂及其NH_3-SCR脱硝性能

通过低温燃烧法(LCS)制备了不同金属硝酸盐与柠檬酸物质的量比的系列Mn-CeO_x(LCS)锰铈催化剂,将其与共沉淀法(CP)制备的Mn-CeO_x(CP)锰铈催化剂相对比,结合XRD、XPS、FESEM和H2-TPR等技术表征,对其NH_3-SCR脱硝催化性能进行了研究。结果表明,金属硝酸盐与柠檬酸的物质的量比是影响Mn-CeO_x(LCS)催化剂脱硝性能的重要因素。虽然两种催化剂中的锰氧化物组分均为无定型,但相较于Mn-CeO_x(CP),Mn-CeO_x(LCS)表面具有较高的锰含量与Oα/(Oα+Oβ)比,其脱硝催化性能也较高;同时,Mn-CeO_x(LCS)锰铈催化剂上有更多的多级孔,有利于气体在催化剂上的吸附和反应。硝酸盐与柠檬酸物质的量比为36∶22的Mn-CeO_x(LCS)锰铈催化剂在80-180℃下脱硝率可达75%-100%;即使通入SO2,180℃下的脱硝率仍可稳定于74%。     

Nickel(II) Schiff base complex supported on nano‐titanium dioxide: A novel straightforward route for preparation of supported Schiff base complexes applying 2,4‐toluenediisocyanate

For the first time, a novel, straightforward and inexpensive route for immobilization of metals in Schiff base complex form is reported applying 2,4‐toluenediisocyanate as a precursor of primary amine group. A nickel(II) Schiff base complex supported on nano‐TiO₂ was designed and synthesized as an effective heterogeneous nanocatalyst for organic reactions, and well characterized using various techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray analysis and thermogravimetric analysis. The catalytic efficiency of the complex was evaluated in selective oxidation of sulfide to sulfoxide by hydrogen peroxide as an oxidant under solvent‐free conditions at room temperature, which successfully resulted in high yield and high conversion of products. Effective factors including solvent type, oxidant and catalyst amount were also optimized. The catalyst shows outstanding reusability and could be impressively recovered for six consecutive cycles without significant change of its catalytic efficiency.     

Extraction Properties of Oligodentate Carbamoylmethylphosphine Oxides and β-Aminophosphine Oxides Toward Lanthanides and Rhenium(VII)

Abstract

The extraction properties of a series of carbamoylmethylphosphine oxides and β-aminophosphine oxides with lanthanide metal ions is presented. Tris[bis(2-diphenyl- phosphorylethyl)-aminoethyl]amine is shown to be highly effective for extraction of Re(VII).     

Diffuse scattering of modulated structures and quasicrystals

The method of Fourier transforms is applied to the calculation of sharp (coherent) and diffuse (incoherent) scattering of modulated structures and quasicrystals. It is shown that the fundamental difference between both may best be described by introducing different distribution functions of atoms, before applying modulations of the structure.     

Liquid-Repellent Metal Oxide Photocatalysts

Metal oxide photocatalysts (MOPCs) decompose organic molecules under illumination. However, the application of MOPCs in industry and research is currently limited by their intrinsic hydrophilicity because MOPCs can be wetted by most liquids. To achieve liquid repellency, the surface needs to possess a low surface energy, but most organic molecules with low surface energy are degraded by photocatalytic activity. Herein, current methods to achieve liquid repellency on MOPCs, while preventing degradation of hydrophobic coatings, are reviewed. Classically, composite materials containing MOPCs and hydrophobic organic compounds possess good liquid repellency. However, composites normally form irregular coatings and are hard to prepare on surfaces such as those that are mesoporous or nanostructured. In addition, the adhesion of composites to substrates is often weak, resulting in delamination. Recent studies have shown that the direct grafting reaction of polydimethylsiloxane (PDMS) from silicone oil (methyl-terminated PDMS) under illumination results in a stable polymer brush. This easy and simple grafting method allows us to create stable liquid-repellent surfaces on MOPCs of various types, structures, and sizes. In particular, super-liquid-repellent drops with an underlying air layer can be created on PDMS-grafted nano-/microstructured MOPCs. Potential applications of surfaces combining liquid repellency and photocatalytic activity are also discussed; thus offering new ways of using MOPCs in a wider range of applications.     

Nucleation of Hematite: A Nonclassical Mechanism

Hematite (α-Fe₂O₃) is thermodynamically stable under ambient conditions, of vast geological importance, and widely used in applications, for example, as corrosion protection and as a pigment. It forms at elevated temperatures, whereas room-temperature reactions typically yield metastable akaganéite or ferrihydrite. The mechanistic key changes underlying this observation were explored in the present study. The entropic contribution to the prenucleation hydrolysis reaction categorically implies the presence of prenucleation clusters (PNCs) as fundamental precursors. The formation of hematite is then due to a change in the reaction mechanism above approximately 50 °C, whereby the reaction limitation towards oxolation in phase-separated clusters is overcome. A model that rationalizes the occurrence of hematite, akaganéite, and ferrihydrite based on the chemistry of olation PNCs is proposed. Supersaturation and the temperature dependence of olation and oxolation rates from monomeric precursors are irrelevant in this nonclassical mechanism.     

Engineering Multifunctional Gold Decorated Dendritic Mesoporous Silica/Tantalum Oxide Nanoparticles for Intraperitoneal Tumor‐Specific Delivery

Nonspecific high‐energy radiation for treatment of metastatic ovarian cancer is limited by damage to healthy organs, which can be mitigated by the use of radiosensitizers and image‐guided radiotherapy. Gold (Au) and tantalum oxide (TaO_x) nanoparticles (NPs), by virtue of their high atomic numbers, find utility in the design of bimetallic NP systems capable of high‐contrast computed tomography (CT) imaging as well as a potential radiosensitizing effect. These two radio‐dense metals are integrated into dendritic mesoporous silica NPs (dMSNs) with radial porous channels for high surface‐area loading of therapeutic agents. This approach results in stable, monodispersed dMSNs with a uniform distribution of Au on the surface and TaO_x in the core that exhibits CT attenuation up to seven times greater than iodine or monometallic dMSNs without either TaO_x or Au. Tumor targeting is assessed in a metastatic ovarian cancer mouse model. Ex vivo micro‐CT imaging of collected tumors shows that these NPs not only accumulate at tumor sites but also penetrate inside tumor tissues. This study demonstrates that after intraperitoneal administration, rationally designed bimetallic NPs can simultaneously serve as targeted contrast agents for imaging tumors and to enhance radiation therapy in metastatic ovarian cancer.     

Fullerene compounds with general formulae C60Ox (x = 1–3): Isomerism,stability and polarizability

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