Utilization of waste vanadium-bearing resources in the preparation of rare-earth vanadate catalysts for semi-hydrogenation of α,β-unsaturated aldehydes

Recycling industrial solid waste not only saves resources but also eliminates environmental concerns of toxic threats. Herein, we proposed a new strategy for the utilization of petrochemical-derived carbon black waste, a waste vanadium-bearing resource (V > 30000 ppm (10 ⁻⁶)). Chemical leaching was employed to extract metallic vanadium from the waste and the leachate containing V was used as an alternative raw material for the fabrication of vanadate nanomaterials. Through the screening of various metal cations, it was found that the contaminated Na⁺ during the leaching process showed strong competitive coordination with the vanadium ions. However, by adding foreign Ce³⁺ and Y³⁺ cations, two rare-earth vanadates, viz., flower-like CeVO₄ and spherical YVO₄ nanomaterials, were successfully synthesized. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier-transform infrared, and N₂ physisorption were applied to analyze the physicochemical properties of the waste-derived nanomaterials. Importantly, we found that rare-earth vanadate catalysts exhibited good activities toward the semi-hydrogenation of α,β-unsaturated aldehydes. The conversion of cinnamaldehyde and cinnamic alcohol selectivity were even higher than those of the common CeVO₄ prepared using pure chemicals (67.2% vs. 27.7% and 88.4% vs. 53.5%). Our work provides a valuable new reference for preparing vanadate catalysts by the use of abundant vanadium-bearing waste resources.     

Meticulously tailoring phase boundary in KNN-based ceramics to enhance piezoelectricity and temperature stability

Although KNN-based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN-based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d₃₃ value in this system reaches 501 pC/N with a T_C ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well-preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric-induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN-based ceramics, which is expected to promote the practical applications in the future.     

Polydopamine‐Assisted Electrochemical Fabrication of Polypyrrole Nanofibers on Bone Implants to Improve Bioactivity

Dopamine is a molecule that facilitates biomineralization, and it is used to prepare electropolymerization‐induced polydopamine (PDA). For the first time, dopamine is used for template‐free electrochemical polymerization to form biocompatible polypyrrole (PPy) nanofiber coatings on bone implants. Dopamine monomers are electropolymerized to PDA chains affixed to biomedical titanium after the nanomicelles are tuned to self‐assemble by triggering the potential, resulting in nanofiber formation. Dopamine serves as a dopant to induce the formation of conductive PPy nanofibers and as a promoter to accelerate biomineralization, cell proliferation, and adhesion.

     

Synthesis,Structure, and Performance of Efficient Red Phosphor LiNaGe4O9:Mn4+ and Its Application in Warm WLEDs

For phosphor‐converted warm white light‐emitting diodes (WLEDs), it is essential to find highly efficient red oxide phosphors, which are better chemically stable and benign to environment and can be prepared in a much milder condition. Here, we report a red phosphor LiNaGe₄O₉:Mn⁴⁺ with a quantum yield up to 78% after systematic optimization in synthesis temperature, dopant concentration of Mn⁴⁺, and sintering time. Best performance of the phosphor can be reached when it is synthesized in a mild reaction condition, that is, at 850°C for 3 h in air. The integrated emission intensity is more than four times stronger than commercial red phosphor 3.5MgO·0.5MgF₂·GeO₂:Mn⁴⁺ (MFG:Mn⁴⁺) under a blue light excitation at 470 nm. Crystal structural analysis reveals that the high efficiency Mn⁴⁺ exhibits in the compound is mainly due to the well separation of GeO₆ groups from each other by GeO₄ tetrahedra in the neighborhood and the ideal substitution of octahedral Ge⁴⁺ site by Mn⁴⁺ in view of both size and charge matches. The high performance of the phosphor encourages us to apply the blue absorbing red phosphor to WLED, which is based on combination of a blue LED chip and YAG:Ce³⁺, and the warm perception WLED is therefore achieved with a color temperature of 3353 K.     

New Natural Pigment Fraction Isolated from Saw Palmetto: Potential for Adjuvant Therapy of Hepatocellular Carcinoma

For the first time, we discovered a small proportion of aqueous fraction from Saw Palmetto apart from the fatty acid-rich fraction exhibited pharmacological activity. Therefore, this study aims to explore the anti-tumor potential of red pigmented aqueous fraction of Saw Palmetto, NYG on human hepatocellular carcinoma and its possible targets. Subcutaneous xenograft and orthotopic implantation models of HCC were used to evaluate the tumor inhibitory effect of NYG. Human hepatocellular carcinoma (HCC) cell lines and human umbilical vein endothelial cells (HUVEC) were used as in vitro model. The mRNA expression was conducted by qPCR. Protein expression was monitored by immunoblotting and immunohistochemistry. Cell migration and blood vessel formation were determined by chamber assay and tube formation assay, respectively. Significant tumor inhibition of NYG in dose-dependent manner was observed on subcutaneous xenograft and orthotopic HCC model. NYG has no direct action on cell viability or VEGF secretion of HCC cells. However, NYG reduced in vitro migration and vessel formation activities of HUVEC cells, as well as in vivo intratumoral neovascularization. NYG attenuated extracellular signal-regulated kinases (ERK) activation in endothelial cells, which may be associated with the suppression of migration and tube formation of HUVEC. NYG suppressed tumor expansion of HCC via inhibiting neovascularization, and may be potential adjuvant treatment for HCC.     

Freestanding fiber mats of zeolitic imidazolate framework 7 via one‐step,scalable electrospinning

We demonstrated the fabrication of freestanding zeolitic imidazolate framework 7 (ZIF‐7) nanofiber (NF) mats by means of one‐step, scalable electrospinning. The formation of ZIF‐7 nanoparticles embedded in polymer fibers was unambiguously pinpointed via X‐ray diffraction, transmission electron microscopy, and adsorption studies. The NF mats exhibited excellent characteristics, with an average diameter of 245 nm, in the adsorption and desorption of carbon dioxide (CO₂); this makes them attractive candidates for gas separation and other selective filtration applications. This excellent property of the ZIF‐7 mats was explained by the gate‐opening phenomenon of ZIF‐7, which yielded a stepwise increase in the overall CO₂ uptake capacity. The mechanical strength of the NF mats was also obtained via large‐strain uniaxial tensile deformation, which enabled preliminary assessment of the mat's suitability for textiles and membranes in targeting separation and filtration applications with large‐area permeability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43788.     

Enhancing General Corrosion Resistance of Biomedical High Nitrogen Nickel-Free Stainless Steel by Nitric Acid Passivation

A systematic study of nitric acid passivation was investigated to enhance the general corrosion resistance of biomedical high-nitrogen nickel-free stainless steels(HNSs).After passivation,the corrosion rate of HNS could dramatically reduce to 1/20 of the untreated in 37℃0.9 wt% NaCl solutions.Then,the passive film on HNS was analyzed by X-ray photoelectron spectroscopy.It was found that chromium enrichment in the passive film and nitrogen enrichment in the film/metal interface contributed to the improvement in general corrosion resistance of HNS.     

Preparation of cerium doped Cu/MIL-53(Al) catalyst and its catalytic activity in CO oxidation reaction

Metal-organic framework (MOF) material MIL-53(Al) with high thermal stability was prepared by a solvothermal method, serving as a support material of cerium doped copper catalyst (Ce-Cu)/MIL-53(Al) material for CO oxidation with high catalytic activity. The catalytic performance between the (Cu-Ce)/MIL-53(Al) and the Cu/MIL-53(Al) catalytic material was compared to understand the catalytic behavior of the catalysts. The catalysts were characterized by thermogravimetric-differential scanning calorimetry (TG-DSC), N₂ adsorption- desorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The characterization results showed that MIL-53(Al) had good stability and high surface areas, the (Ce-Cu) nanoparticles on the MIL-53(Al) support was uniform. Therefore, the heterogeneous catalytic composite materials (Ce-Cu)/MIL-53(Al) catalyst exhibited much higher activity than that of the Cu/MIL- 53(Al) catalyst in CO oxidation test, with 100% conversion at 80 °C. The results reveal that (Cu-Ce)/MIL- 53(Al) is the suitable candidate for achieving low temperature and higher activity CO oxidation catalyst of MOFs.     

利用纳米TiO2微胶粒实施对云母钛珠光颜料表面修饰的研究

本文以光化学反应制备的纳米TiO2微胶粒实施对云母钛珠光颜料表面修饰,以改善其珠光效应.实验表明此种方法可使颜料的平均反射率提高5%以上,效果明显.从结构入手研究了其修饰机理;探讨实验的工艺参数、晶型转化、杂质离子等对珠光颜料光学性能的影响.     

规整填料塔的壁流量计算

推导了板波纹填料塔的壁流量计算方法 ,并探讨填料层分段高度的选择。