Magnetic solid‐phase extraction based on carbon nanosphere@Fe3O4 for enantioselective determination of eight triazole fungicides in water samples

In this work, a carbon nanosphere decorated by Fe₃O₄ nanoparticles was prepared, characterized and used as the magnetic adsorbent. Eight commonly used chiral triazole fungicides, including penconazole, uniconazole, paclobutrazol, triazolone, tebuconazole, hexaconazole, triticonazole and epoxiconazole were extracted from two environmental water samples (river water and lake water) by magnetic solid‐phase extraction, followed by the enantiomeric analysis on a Chiralpark IC column coupled with a triple quadrupole mass spectrometry to evaluate their possible stereoselective degradation occurring in the water samples. The possible factors affecting the extraction performance, such as amount of used adsorbents, pH and ionic strength of water solution, types and volumes of desorption solvents were systematically investigated. Under the optimum conditions, extraction yields of eight triazole fungicides were above 80% and the concentration factors were as high as 1000. Method detection and quantification limits for the enantiomers of eight triazole fungicides were in the range of 0.56–6.95 ng/L. Satisfactory accuracy (relative recovery 77.8–93.5%), good intraday precision (RSD 4.3–9.8%) and interday precision (RSD 3.1–7.9%) were also obtained. The developed method provided the simplicity of operation, rapidity and high enrichment factor, which can be used to monitor and evaluate the behavior of the individual enantiomer of chiral triazole fungicides.     

氧化石墨烯/多壁碳纳米管负载金铂核壳纳米粒子构建一种三维新型抗坏血酸电化学传感器

该文采用涂覆的方式构建了一种用于灵敏检测抗坏血酸(AA)的电化学传感器。先将多壁碳纳米管(MWCNTs)和氧化石墨烯(GO)混合悬浮液修饰在玻碳电极(GCE)表面,修饰的GO可有效防止MWCNTs聚集,再将具有良好电催化性能的金铂核壳纳米粒子(Au@Pt NPs)修饰在GO/MWCNTs电极上,层层组装构建形成GO/MWCNTs/Au@Pt NPs/GCE三维新型抗坏血酸电化学传感器。该修饰电极在磷酸缓冲溶液中对AA显示了较宽的线性范围和极低的检出限,氧化峰电流与AA浓度在0.005～0.5μmol/L和0.5～1 000μmol/L范围内呈良好的线性关系,相关系数均为0.999,检出限(S/N=3)为4×10~(-9) mol/L,稀释人体血清样品的加标浓度为0.01、0.1、10μmol/L,回收率为90.9%～108%,相对标准偏差(RSD,n=3)为1.2%～2.8%。该修饰电极对AA具有良好的选择性,可有效排除多巴胺、尿酸、葡萄糖等生物小分子的干扰。方法简单、高效、灵敏,可用于临床实际检测。     

Radiative quantum efficiency of CdSe/ZnS core-shell colloidal solutions: Size-dependence

Thermo-optical parameters of CdSe/ZnS core-shell nanoparticles suspended in toluene were measured using a thermal lens (TL) technique. TL transient measurements were performed using the mode-mismatched dual-beam (excitation and probe) configuration. A He-Ne laser at λ_p = 632.8 nm was used as the probe beam and an Ar⁺ laser (at λ_e = 514.5 nm) was used as the excitation beam for studies as a function of both core size and concentration of CdSe/ZnS nanocrystals. The fraction thermal load (φ) and radiative quantum efficiencies (η) of the CdSe/ZnS were determined. Dependence on core size (∼2-5 nm) and concentration (∼0.01-0.62 mg/ml) was observed for both φ and η parameters.     

金纳米颗粒的有序制备及其光学特性

采用纳米球蚀刻技术在石英衬底上制备了不同高度的金纳米颗粒阵列.通过扫描电子显微镜对其表面形貌进行了观测,表明金纳米颗粒为有序分布的三棱柱结构.通过红外—紫外吸收光谱仪在190—900nm波长范围内对其光吸收特性进行了测量, 并成功观测到了金纳米颗粒表面等离子体振荡效应引起的光吸收峰,结果表明随着金纳米颗粒高度的增加,其吸收峰的位置向短波方向移动(蓝移).同时对金纳米颗粒的光吸收特性进行了基于离散偶极子近似的理论计算,并与实验结果进行了比较. 关键词： 纳米球蚀刻技术 金纳米颗粒 离散偶极子近似     

Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System

研究了钴碳核壳微球在超临界二氧化碳体系中的合成过程. 在密闭的不锈钢高压反应釜中,适量的二茂钴和干冰在350 oC下,反应12 h后合成直径大约1 μm的钴碳核壳微球。通过X射线衍射、X射线光电子谱、透射电子显微镜、傅利叶红外光谱(FT-IR)以及拉曼光谱的分析,钴碳核壳微球是由直径小于1 μm的非晶钴核和厚度约为200 nm的非晶碳壳组成. 其生长机理可能是：二茂钴在超临界二氧化碳体系中的热分解,带单电子的碳原子或基团由于磁性作用沉积在磁性的钴核上. 由于非晶碳壳的存在,钴碳核壳微球的磁饱和强度141.     

消光式核壳二聚体传感器的设计与光谱特性分析

根据ITO/Au纳米核壳二聚体粒子在生物医学领域的应用合理性,设计了一种实时检测生物液体的核壳二聚体探针消光式传感器;由偶极子理论推导出输出波长与外界环境折射率关系;利用MATLAB设计ITO/Au纳米核壳二聚体粒子结构;采用软件DDSCAT7.3结合离散偶极近似法,利用二聚体有效半径模拟计算了300~950nm可见光到红外光波段不同核壳比、二聚体间距、以及不同介质折射率的消光光谱;根据传感芯片折射率与偶极共振、耦合八级共振的响应关系得出ITO/Au二聚体的折射率灵敏特性。与传统Ag/Au核壳纳米粒子相比,ITO/Au纳米核壳二聚体结构引入了可作为传感芯片灵敏性自参考参数的耦合八级共振峰,同时ITO/Au二聚体结构的折射率灵敏度可达到419nm/RIU。这些工作及其结果对制作消光式传感器具有重要的意义。     

Porous MoO3@SiC hallow nanosphere composite as an efficient oxidative desulfurization catalyst

A novel N‐doped MoO ₃ @SiC hollow nanosphere has been synthesized through two steps. Due to the first step, N‐doped MoO₂@C nanosphere was synthesized using the hydrothermal method and in the second step, Si‐C bonds were formed through the low‐temperature magnesiothermic method and MoO ₃ @SiC hollow nanosphere was produced. The prepared nanostructures were identified by various techniques such as IR, XRD, XPS, BET/BJH, SEM/EDS, and Raman spectroscopy. Results show that converting of C to SiC increase the surface area from 17 to 241 m²/g with remarkably decrease in pore diameter. Also, molybdenum is present in the form of MoO₂ in carbon catalyst while during magnesiothermic process, it transfers to MoO₃ form in the SiC catalyst. The synthesized products were employed as catalysts in oxidative desulfurization of model fuel. The results displayed that MoO ₃ @SiC hollow nanostructure shows a superior catalytic activity (99.9%, 40 min) compared to C support (56%, 60 min). Furthermore, the recycling of MoO₂@C catalyst shows a dramatic decrease even after the first run, while, SiC support exhibit higher stability during the stronger interaction between molybdenum catalyst and SiC support.     

Carbon Sphere@Nickel sulfide core-shell nanocomposite for high performance supercapacitor application

The Carbon sphere@Nickel sulfide core-shell nanocomposites for different mole ratios of Carbon sphere (0:1; 0.5:1 and 1:1) have been synthesized by a facile low temperature water-bath method without any further calcination. XRD studies on the core-shell nanocomposites show that characteristic peaks associated with rhombohedral phase structure of nickel sulfide have been retained. TEM morphology presents the interlinked core-shell of Carbon sphere@Nickel sulfide composite with grass-leaf dexterity for better ionic diffusion. BET study confirms the formation of mesoporous structure with high surface area. The existence of elements and its electronic configuration is noted through XPS. The electrochemical studies on pristine nickel sulfide and its Carbon sphere@Nickel sulfide core-shell composites reveal that Carbon sphere@Nickel sulfide (0.5:1) exhibits high specific capacitance of 1022?F?g^?1 at a current density of 1?A?g^?1. It shows good cyclic performance even beyond 4000 consecutive charge/discharge cycles at a relatively high current density of 20?A?g^?1 with the ～83% of retention.     

In-situ preparation and electrochromic properties of TiO2/PTPA-HTAN core-shell nanocomposite film

A new star-shaped structure conjugated microporous polymers, poly (2,8,14-tri[4-diphenyl-benzene]-hexaazatrinaphthylene) (PTPA-HATN), was designed and in-situ electrochemically polymerized on the surfaces of FTO electrodes with a directional alignment TiO₂ nanorod array to obtain TiO₂/PTPA-HATN core-shell nanocomposite films. Compared with the PTPA-HATN film, the TiO₂/PTPA-HATN composite film exhibits higher optical contrast and faster response time, with contrast of 57% at 783 nm, coloring time of 3.62 s and discoloring time of 2.55 s (43%, 4.63 s and 4.77 s for PTPA-HATN film, respectively). After 400 cycles, the contrast of nanocomposite film decreased by 28%, while the PTPA-HATN film basically lost its electrochromic properties. A simple three-layer EC prototype device based on TiO₂/PTPA-HATN nanocomposite film constructed with hydrogel electrolyte clearly shows color changes at different voltages. On the one hand, the formation of core-shell porous nanostructure of TiO₂/PTPA-HATN composite film provides a larger ion doping/de-doping interface, shortening the average diffusion length of ions. On the other hand, the large indented polymer-nanorods contact interface makes it difficult for the polymer to detach from the electrode, thus significantly improving the cyclic stability of the composite film.     

单颗粒稀土纳米晶的三基色上转换发光

可调谐发光颜色的上转换荧光纳米粒子具有广阔的应用前景。本文设计并成功合成了结构紧凑的多层核-壳纳米颗粒。在不同波段激光的泵浦下,该颗粒中不同壳层分别产生红、绿、蓝3种颜色的上转换荧光。光谱测试结果表明,样品三基色发光的颜色纯度较好,并且可以实现全色域的颜色实时调节。此外,还测试了样品发光强度与泵浦功率之间的依赖关系,用于研究其中的上转换发光机理。这种在单颗粒水平上具有全色域可调发光的紧凑核-壳结构纳米晶体在多通道生物检测及成像、超高分辨率显示器件、高端防伪应用等领域显示出巨大的潜力。