PMAA microgel surface-supported phase transfer catalyst as reusable microreactors for ultra-deep desulfurization

The reusable microreactors, poly(methacrylic acid) (PMAA) microgels surfacely covered with 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (AEM) and K₂{W(=O)(O₂)₂(H₂O)}₂ (W2) complexes, have been synthesized by using an ion exchange reaction between AEM located on PMAA microgels and W2 in aqueous solution. The final composite microspheres and intermediate products are characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrophotometer, and thermogravimetric analysis, respectively. The results indicated the PMAA/AEM/W2 composite microspheres with surface-wrinkling morphology and core-shell structure. The feasibility of the composite microspheres used as reusable microreactors in catalytic oxidation of dibenzothiophene (DBT) was investigated. Additionally, the effects of some factors, including the amount of the microreactors, temperature, H₂O₂/DBT molar ratio, the loaded amount of AEM, DBT concentration, and recycling times, on the catalytic oxidation were examined. The results demonstrated that the prepared composite microspheres possess high catalytic performance and reusability in the catalytic oxidation of DBT.     

Production from ilmenite of TiO2-supported catalysts for selective catalytic reduction of NO with NH3

Economic production of titanium dioxide (yield >98 %) from ilmenite has been achieved by use of a modified sulfate reduction process. A series of samples were prepared by varying the concentration of titanium dioxide nuclei (0.2, 0.3, and 0.6 %) and further impregnation with antimony and vanadia. The structural and acidic properties of the samples were comprehensively studied by X-ray diffraction (XRD), transmission electron microscopy, BJH pore size distribution, and temperature-programmed desorption of NH₃. The XRD results revealed the presence of intense peaks from anatase titanium dioxide. Enhancement of surface area was observed for second-time filtered samples, possibly because of loss of iron from the bulk. As a result, formation of additional micropores was apparent from N₂ adsorption and desorption isotherms. Among all the antimony and vanadia-doped samples, the first-time filtered sample with the low concentration of nuclei (0.2 %) had the highest catalytic activity at low temperatures, owing to its larger pore size and abundant acidic species.     

Preparation and photoelectrochemical performance of PbSe/BaTiO3/TiO2 composite film

By dipping-lifting in sol–gel solution and reducing process, the TiO₂ composite film on the glass plate was first prepared. Then, the PbSe/BaTiO₃/TiO₂ composite film was fabricated by interface reaction with BaTiO₃ and PbSe on the surface of TiO₂ composite film. The characterization results show that the uniform porous TiO₂ film is made up of the anatase crystal, and the PbSe/BaTiO₃/TiO₂ composite film is constructed by doping or depositing BaTiO₃ and PbSe nanoparticles on the surface of TiO₂ film. The photoelectrochemical measurement results indicate that the PbSe/BaTiO₃/TiO₂ composite film has an interesting photoelectrochemical conversion property.     

Excellent degradation performance of azo dye by metallic glass/titanium dioxide composite powders

The metallic glass/titanium dioxide powders (MG/TiO₂) with enhanced photocatalytic oxidation activity were synthesized, which exhibit a higher efficiency in decolorizing methylene blue solutions (MB). Compared with the pure TiO₂ and crystalline alloy/TiO₂ (CA/TiO₂) under the same circumstances, its degradation rate was 60 % and 30 % higher, respectively. Furthermore, compared with the CA/TiO₂, the MG/TiO₂ photocatalytic rate was three times faster when decolorizing MB. Considering the excellent intrinsic high-performance photocatalytic degradation under visible light irradiation, these novel powders were proven to have potential applications in water purification industry.     

Instant Visual Detection of Picogram Levels of Trinitrotoluene by Using Luminescent Metal–Organic Framework Gel‐Coated Filter Paper

There is an ongoing need for explosive detection strategies to uncover threats to human security including illegal transport and terrorist activities. The widespread military use of the explosive trinitrotoluene (TNT) for landmines poses another particular threat to human health in the form of contamination of the surrounding environment and groundwater. The detection of explosives, particularly at low picogram levels, by using a molecular sensor is seen as an important challenge. Herein, we report on the use of a fluorescent metal–organic framework hydrogel that exhibits a higher detection capability for TNT in the gel state compared with that in the solution state. A portable sensor prepared from filter paper coated by the hydrogel was able to detect TNT at the picogram level with a detection limit of 1.82 ppt (parts per trillon). Our results present a simple and new means to provide selective detection of TNT on a surface or in aqueous solution, as afforded by the unique molecular packing through the metal–organic framework structure in the gel formation and the associated photophysical properties. Furthermore, the rheological properties of the MOF‐based gel were similar to those of a typical hydrogel.     

Graphene Oxide Protected Nucleic Acid Probes for Bioanalysis and Biomedicine

Recently, the binding ability of DNA on GO and resulting nuclease resistance have attracted increasing attention, leading to new applications both in vivo and in vitro. In vivo, nucleic acids absorbed on GO can be effectively protected from enzymatic degradation and biological interference in complicated samples, making it useful for targeted delivery, gene regulation, intracellular detection and imaging with high uptake efficiencies, high intracellular stability, and very low toxicity. In vitro, the adsorption of ssDNA on GO surface and desorption of dsDNA or well‐folded ssDNA from GO surface result in the protection and deprotection of DNA from nucleic digestion, respectively, which has led to target‐triggered cyclic enzymatic amplification methods (CEAM) for amplified detection of analytes with sensitivity 2–3 orders of magnitude higher than that of 1:1 binding strategies. This Concept article explores some of the latest developments in this field.     

Investigation and Comparison of the Mechanistic Steps in the [(Cp*MCl2)2] (Cp*=C5Me5; M=Rh,Ir)‐Catalyzed Oxidative Annulation of Isoquinolones with Alkynes

The mechanism of the [(Cp*MCl₂)₂] (M=Rh, Ir)‐catalyzed oxidative annulation reaction of isoquinolones with alkynes was investigated in detail. In the first acetate‐assisted C? H‐activation process (cyclometalated step) and the subsequent mono‐alkyne insertion into the M? C bonds of the cyclometalated compounds, both Rh and Ir complexes participated well. However, the desired final products, dibenzo[a,g]quinolizin‐8‐one derivatives, were only formed in high yield when the Rh species participated in the final oxidative coupling of the C? N bond. Moreover, a Rh^I sandwich intermediate was isolated during this transformation. The iridium complexes were found to be inactive in the oxidative coupling processes. All of the relevant intermediates were fully characterized and determined by single‐crystal X‐ray diffraction analysis. Based on this mechanistic study, a Rh^III→Rh^I→Rh^III catalytic cycle was proposed for this reaction.     

Preparation and characterization of oxidized regenerated cellulose film for hemostasis and the effect of blood on its surface

Hemostatic effects of oxidized regenerated cellulose (ORC) are well-known but its mechanism has never been demonstrated clearly. Since thrombus formation is a kind of surface phenomenon, we changed the morphology of cellulose to form a kind of membrane with ionic liquid as solution, and also we prepared ORC films with nitrogen dioxide(NO₂)/carbon tetrachloride(CCl₄) oxidation system reacting for 16, 40, 64 and 88 h, respectively. FTIR and NMR spectra showed that NO₂/CCl₄ oxidation system had a high selectivity on hydroxyl group at C6 of regenerated cellulose. With the oxidation time prolonging, the carboxyl content was enhanced and the DP was reduced. The XPS results suggested that a new carboxyl bond was formed due to the increasing of oxygen content. From contact angle analysis, the wettability of blood on the ORC film surface was better than that of the regenerated cellulose film, which was beneficial for the blood to spread. SEM photographs showed that the ORC film oxidized for 40 h could adsorb and activate more platelets and erythrocytes. Hemostatic evaluation and enzyme-linked immunosorbent assay indicated that the ORC film had a dramatic hemostatic performance, and the products of platelets release reaction, activated platelets glycoprotein and activated clotting enzymes were increased simultaneously. Moreover, the possible mechanism of the hemostasis for ORC film was discussed.     

亲水性相互作用色谱-串联质谱联用法检验鱼塘水中的草甘膦

建立了亲水性相互作用色谱-串联质谱联用法检验鱼塘水中草甘膦的方法。样品经去离子水提取,C18固相萃取柱和滤膜净化后,以0.5%异丙胺-乙腈为流动相,亲水性相互作用色谱柱分离,负离子扫描和多反应监测模式质谱监测,基质匹配标准溶液外标法定量。草甘膦质量浓度在10～1000 ng/mL范围内线性良好(r≥0.9973),日内、日间精密度RSD≤10%(n=5),鱼塘水中草甘膦的回收率在90%以上。该方法不需衍生化,净化步骤简便快捷,定量准确,可满足侦查和诉讼中草甘膦的检测要求。     

改进片铸与烧结技术制备高性能钕铁硼磁体的研究

通过优化合金成分设计与改进速凝片铸技术、烧结技术,应用国内通用的工业生产烧结钕铁硼磁体的各类原材料,在工业生产线上实现了45UH高性能烧结钕铁硼磁体的批量生产。SEM观察和XRD分析结果表明:磁体具有比较高的取向度;其显微组织致密、精细而均匀,平均晶粒尺寸约为5μm。45UH烧结钕铁硼磁体的典型磁性能为Br=1.363 T,Hcb=1060 kA.m-1,Hcj=2140 kA.m-1,Hk=1625 kA.m-1,(BH)max=366.0 kJ.m-3;其Hcj/79.6 kA.m-1+(BH)max/7.96 kJ.m-3=72.8。在295～453 K温度区间,其剩磁与内禀矫顽力的温度系数分别为-0.108%.K-1和-0.486%.K-1。当L/D=0.7时,在473 K保持2 h磁体开路磁通不可逆损失为4.1%左右。批量生产的45UH烧结钕铁硼磁体,其常温磁性能优异,温度稳定性良好。