镍铁水滑石及其衍生混合氧化物的制备和表征

采用共沉淀法合成了Ni/Fe摩尔比为1、2、3、6和10的NiFe水滑石。热重-差热结果显示NiFe水滑石的分解有二个过程，分别对应于200℃和300℃的吸热峰。经400℃焙烧后，NiFe水滑石转变为具有较高表面积的NiFeO混合氧化物(约100 m²/g)，其XRD结果仅显示NiO的衍射峰；经800℃焙烧后，NiFeO仍有15 m²/g左右的表面积。穆斯堡尔谱测定表明NiFeO混合氧化物较Fe₂O₃易还原。     

Modified drug release system based on Sulindac and layered double hydroxide: An in vivo Raman investigation

In this study, the capability of a Layered Double Hydroxide (LDH) to promote the modified-release of Sulindac (Sul), a non-steroid anti-inflammatory drug, was followed by Raman spectroscopy through in vitro and in vivo assays. The drug and the LDH-Sul system were pressed into pellets and their dissolution under controlled conditions was monitored in vitro for 80 h. For the in vivo assays, LDH-drug and LDH-Cl (with chloride in the interlayer space) pellets were implanted between the external and internal oblique muscles of Wistar rats. The pellets were removed after 7, 21, 28 and 35 days from implantation and up to 21 days there was an increase in the amount of intercalated carbonate ions as followed over time by Raman microscopy. The carbonate ions are from the extracellular fluid (conjunctive tissue) and replace the chloride ions between the LDH layers. The same kind of ion exchange was observed for LDH-Sulindac: ca. 50% of the drug was released in vivo after 21 days, whereas in vitro the same amount of drug was delivered within 24 h. The release kinetics was much slower in the in vivo assay due to a significantly smaller hydrodynamic interaction inside the muscle.     

γ‐Fe2O3@Cu3Al‐LDH‐TUD as a new Amphoteric,Highly Efficient and Recyclable Heterogeneous Catalyst for the Solvent‐free Synthesis of Dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens

Thiourea dioxide was immobilized on γ‐Fe₂O₃@Cu₃Al‐LDH magnetic nanoparticles to prepare the γ‐Fe₂O₃@Cu₃Al‐LDH‐TUD MNPs. The structure and properties of these magnetic nanoparticles were established by FT‐IR, EDX, SEM, XRD, and hystogram of particle size analytical methods. The results obtained from these analytical methods confirmed the successful immobilization of the thiourea dioxide onto the magnetic support. The synthesized magnetic nanoparticles (MNPs) exhibited high catalytic activity in one‐pot three‐component reactions under mild and solvent‐free conditions for the synthesis of diverse ranges of dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens. All the reactions proceeded smoothly to furnish the respective products in excellent yields. Simple isolation of the products, avoidance of harmful organic solvents, versatility of the catalyst and its easy magnetic separation and reusability with no significant loss of activity are the main advantages of the present method.     

Oxido‐peroxido W(VI)‐histidine–MgAl‐layered double hydroxide composite as an efficient catalyst in sulfide oxidation

Oxido‐peroxido W(VI)‐histidine–MgAl‐layered double hydroxide composite was prepared by using MgAl‐layered double hydroxide as a host and oxido‐peroxido W(VI)‐histidine complex as a guest. The composite was characterized by XRD, IR, EDX,SEM and TEM techniques. This composite is tested for catalytic selective sulfoxidation reactions using hydrogen peroxide as oxidant showing good to moderate conversion along with high selectivity.     

红外光谱技术在纳米NiFe2O4制备过程中的应用

采用溶胶-凝胶法制备NiFe2O4纳米粉末,并经不同温度热处理.测定了制备过程中各阶段的红外吸收光谱和不同温度处理样品的红外漫反射光谱.结果表明,红外吸收光谱较好地反映了溶胶-凝胶法制备NiFe2O4纳米粉末过程中结构的变化,为确定热处理温度提供了实验依据,彻底消除有机物,热处理需在400℃以上;红外漫反射谱可以较好地反映粉末的尺寸效应和形态效应,粉末粒径越小,漫反射函数(K-M)值越大;当粒径达到一定尺寸时,红外漫反射的尺寸效应消失.     

Ta,Ta/Cu缓冲层对NiFe/Fe Mn双层膜交换偏置场的影响

采用磁控溅射方法制备了分别以Ta和Ta/Cu作为缓冲层的一系列NiFe/FeMn双层膜.实验发现,以Ta为缓冲层的NiFe/FeMn双层膜的交换偏置场比以Ta/Cu为缓冲层的NiFe/FeMn双层膜的交换偏置场大.测量了这两种双层膜的织构、表面粗糙度和表面成分.结果表明,以Ta/Cu为缓冲层时,Cu在NiFe层的上表面偏聚是造成NiFe/FeMn双层膜交换偏置场降低的重要原因. 关键词： NiFe/FeMn 交换偏置场 织构 表面粗糙度     

Novel NiFe/Si/Au magnetic nanocatalyst: Biogenic synthesis,efficient and reusable catalyst with enhanced visible light photocatalytic degradation and antibacterial activity

The aim of this paper is to biosynthesize NiFe₂O₄/SiO₂/Au (NiFe/Si/Au) magnetic nanocatalyst using the sonochemical method. This is the first study to synthesize this compound using this method. To obtain optimum morphology and size of products, the synthesis was performed in the presence of polyvinylpyrrolidone, maltose, glucose, and fructose as capping agents and Crataegus pentagyna leaf extract and NaBH₄ as reducing agents. Vibrating-sample magnetometer, field-emission scanning electron microscopy, Fourier-transform infrared, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and differential reflectance spectroscopy techniques were performed to confirm the preparation of magnetic products. The as-synthesized magnetic samples were used to enhance the photocatalytic degradation and antibacterial activity. The NiFe/Si/Au nanocatalysts exhibited an excellent photocatalytic activity by degradation of rhodamine b, methylene blue, and erythrosine as organic contaminants under ultraviolet and visible light irradiation. The degradation curves illustrate that the degradation of anionic dyes is more than that of cationic dyes. In addition, antibacterial activity of as-prepared nanocatalyst against seven bacterial species was investigated. Because of their antibacterial effects, as-synthesized products show a high antibacterial activity against various bacteria. Consequently, the NiFe/Si/Au nanocatalysts with high antibacterial activity and excellent potential photocatalyst activity can be used in environmental and medical sciences for wastewater treatment.     

Nickel ferrite spinel as catalyst precursor in the dry reforming of methane:Synthesis,characterization and catalytic properties

Dry reforming of methane by CO2 using nickel ferrite as precursor of catalysts was investigated.Nickel ferrite crystalline particles were prepared by coprecipitation of nitrates with NaOH or ammonia followed by calcination,or by hydrothermal synthesis without calcination step.The textural and structural properties were determined by a number of analysis methods,including X-ray diffraction (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS),among which X-ray diffraction (XRD) was at room and variable temperatures.All synthesized oxides showed the presence of micro or nanoparticles of NiFe2O4 inverse spinel,but Fe2O3 (hematite) was also present when ammonia was used for coprecipitation.The reducibility by hydrogen was studied by temperature-programmed reduction (TPR) and in situ XRD,which showed the influence of the preparation method.The surface area (BET),particle size (Rietveld refinement),as well as surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied according to the synthesis method.The catalytic reactivity was investigated using isopropanol decomposition to determine the acid/base properties.The catalytic performance of methane reforming with CO2 was measured with and without the pre-treatment of catalysts under H2 in 650-800 C range.The catalytic conversions of methane and CO2 were quite low but they increased when the catalysts were pre-reduced.A significant contribution of reverse water gas shift reaction accounted for the low values of H2 /CO ratio.No coking was observed as shown by the reoxidation step performed after the catalytic reactions.The possible formation of nickel-iron alloy observed during the study of reducibility by hydrogen was invoked to account for the catalytic behavior.     

甘氨酸存在条件下水热合成可层离双氢氧化物

在甘氨酸存在条件下,经混合金属盐溶液在pH为10．0时共沉淀后的水热反应,可成功合成甘氨酸插层的镁铝双氢氧化物(Gly-LDHHTT)．产物以XRD、IR、TEM／SEM、TG／DTA等技术进行表征．结果表明,120℃水热合成10 h的产物晶型完善,沿a和c方向的晶粒尺寸最大,产物热稳定性好．TEM观察晶粒呈明显的六边形,SEM形貌呈现边缘略有卷曲的团聚薄片．通过进一步探讨甘氨酸插层镁铝双氢氧化物层离的机制后,获得了在室温下实现水热合成产物快速层离的方法,为层离-吸附法成功运用于双氢氧化物／聚合物纳米复合材料制备体系中提供重要的实验基础．