Generation of paramagnetic hybrid inorganic/organic thin films

There is a growing interest in developing advanced materials for thin film applications in biology, electronics, photonics and engineering. We report the development of hybrid inorganic/organic thin films containing nickel, iron and cobalt paramagnetic materials. By etching the resist in oxygen plasma after processing, most of the organic component of the resist was removed. The elemental chemical composition of the films was confirmed by energy dispersive X‐ray spectroscopy. This process can potentially lead to patterning paramagnetic thin films containing paramagnetic materials by following standard photolithography protocols, obviating the need for a wet or vacuum metal deposition. Copyright © 2010 John Wiley & Sons, Ltd.     

Supercharacters,symmetric functions in noncommuting variables,and related Hopf algebras

We identify two seemingly disparate structures: supercharacters, a useful way of doing Fourier analysis on the group of unipotent uppertriangular matrices with coefficients in a finite field, and the ring of symmetric functions in noncommuting variables. Each is a Hopf algebra and the two are isomorphic as such. This allows developments in each to be transferred. The identification suggests a rich class of examples for the emerging field of combinatorial Hopf algebras.     

Horseradish peroxidase-loaded nanospheres attached to hollow gold nanoparticles as signal enhancers in an ultrasensitive immunoassay for alpha-fetoprotein

We report on a novel electrochemical signal amplification strategy for use in immunoassays. The highly responsive immunoelectrode was constructed in the following way: (1) The surface of a gold electrode was covered with a layer single-walled carbon nanotubes dispersed in chitosane functionalized with L-cysteine; (2) Gold nanoparticles containing protein A and anti-alpha-fetoprotein (anti-AFP) were then covalently attached to the surface via the thiol groups of the chitosane. The electrode is then exposed to the analyte (AFP) which then is bound by the antibody. In the next step, a gold-conjugated secondary antibody is added that was prepared in the following way: (1) Horseradish peroxidase was crosslinked and the resulting spheres were coated with hollow gold nanoparticles (hollow Au-NPs) to give nanospheres of ~100 nm in diameter. (2) These were the coated with thionine and, in a last step, with secondary antibody. The use of these materials has several attractive features: The HRP-NPs functionalized with hollow Au-NPs possess a large surface area that can load the large amount of secondary antibody. Thionine (Thi) is highly redox active and improves the intensity of the signal. Carbon nanotubes were used because they possess an excellent electron transfer rate and large surface area. Following incubation of the modified electrode (a) with a sample containing AFP, (b) then with the secondary antibody, and (c) with washing buffer, the electrode is placed in a solution containing H₂O₂. The HRP in the smart secondary antibody causes the catalytic decomposition of H₂O₂ and the results in an electrical current that is linearly related to the concentration of AFP in the 0.025 to 5.0 ng mL^?1 concentration range. The detection limit for AFP is as low as 8.3 pg mL^?1. We believe that this novel kind of immunoassay represents a promising tool for use in sensitive clinical assays.

全光纤平顶3×3光学梳状滤波器的改进

为改善全光纤3×3光学梳状滤波器(Interleaver)的输出特性,详细推导了其输出表达式,通过分析和优化,提出了新的结构参数。计算结果表明:相对于以往的全光纤3×3光学梳状滤波器而言,利用优化后的结构参数设计的全光纤3×3光学梳状滤波器,不仅降低了器件的制作难度,而且在串扰特性、信道隔离度、阻带抑制、通带平顶度以及过渡带滚降等特性方面得到了明显改善,信道间功率旁瓣降低了约16 d B。最后进行了实验研究,实验所得结果与理论结果相吻合。     

Sensitivity limitation by polarization and birefraction in IORG

Integrated optical resonance gyroscope (IORG), with the ring resonator fabricated by micro-techniques, has the advantage of miniaturization, integration, and low cost. Theoretical calculation shows its potential ability in getting high sensitivity. However, the current IORG sensitivity is restricted by optical parasitical noises aggravated by involving high coherent laser source. Polarization fluctuation is one of the dominant noise sources in waveguide resonator. The effect on polarization noise in IORG by three main parameters: state of polarization of the input light, polarization-maintaining quality of the waveguide, and temperature fluctuation of the peripheral environment, has been theoretically analyzed and experimentally tested. An improved layout, with a Planar Lightwave Circuit (PLC) acting as both modulator and polarizer, is presented to suppress the polarization noise in IORG. The results show that the bias instability of IORG caused by polarization noise is greatly reduced from 1.57°/s to 0.005°/s.     

In situ bioinspired synthesis of silver chloride nanocrystals on silk fibroin fibers

Silver chloride (AgCl) nanocrystals were formed and grown on silk fibroin fibers (SFFs) by a room-temperature process. Practically, the degummed SFFs were immersed into silver nitrate solution and sodium chloride solution in turn. The amino acids on the SFF surface were negatively charged in alkaline impregnant, providing locations to immobilize silver ions and form silver chloride seeds. AgCl nanocrystals can further grow into cubic AgCl nanocrystals with an edge of about 100 nm. The morphologies of the AgCl nanocrystals were mostly influenced by the concentration of sodium chloride solution and the special configurations of the SFFs. The target AgCl/SFF nanocomposites constructed by AgCl nanocrystals and substrate SFFs could be used as photocatalysts in water splitting and antibacterial agents. This work provides an important example in the introduction of natural biofibers to the synthesis of functional hybrid nanocomposites by a green and mild technique.     

The assignment of Co-C bond stretching vibrational frequency of CH3Co(DH)2H2O in IR and Raman spectra

Abstract

In order to aid assignment of Co-C bond stretching vibrational frequency of CH₃Co(DH)₂H₂O (DH=dimethylgIyoximato monanion) in IR and Raman spectra, its isotopic substitution CD₃Co(DH)₂H₂O has been synthesized and normal coordinate analyses on the two complex have been made. The bands were assigned in terms of potential energy distribution. The results provide definitive band assignment of the Co-C bond and Co-N bond stretching modes which are coupling at 511 cm^?1.     

A Novel Electrochemical Sensor Based on Reduced Graphene Oxide–TiO2 Nanocomposites with High Selectivity for the Determination of Hydroxychloroquine

Russian Journal of Electrochemistry - A simply sensitive sensor based on a reduced graphene oxide–TiO2 nanocomposite modified glassy carbon electrode (RGO–TiO2/GCE) was developed for...     

高效液相色谱-串联质谱法测定蜂蜜中的阿莫西林残留量

建立了高效液相色谱-串联质谱测定蜂蜜中阿莫西林残留的方法。样品用磷酸氢二钾溶液提取,经固相萃取柱进行净化提取后,以C18柱为分离柱,甲醇和0.1%(v/v)甲酸水溶液为流动相,用串联质谱仪检测,选择1个母离子和2个子离子进行选择反应监测,选择信号最强的子离子进行定量测定。该方法采用外标法定量,在2.0～100.0 μg/L范围内,阿莫西林的峰面积与其质量浓度呈良好的线性关系(r2＞0.99),方法的检出限和定量限分别为2.0 μg/kg和5.0 μg/kg,回收率范围为74.2%～81.7%,日内精密度范围为2.8%～7.8%,日间精密度范围为9.1%～11.3%。该方法简便快捷,可以用于蜂蜜中阿莫西林残留量的测定。     

Porous redox-active Cu2O-SiO2 nanostructured film: Preparation, characterization and application for a label-free amperometric ferritin immunosensor

A novel Cu₂O-SiO₂ nanostructured particle was synthesized by a solution-phase method and was adopted for construction of a label-free amperometric immunosensor. The porous Cu₂O-SiO₂ nanoparticles had good redox electrochemical activity, large surface-to-volume ratio, film-forming ability and high stability. The physical morphology and structure of Cu₂O-SiO₂ nanoparticles were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The chemical component of Cu₂O-SiO₂ was confirmed by X-ray photoelectron spectroscopy (XPS) and auger electron spectra (AES). The electrode modification process was probed by cyclic voltammetry (CV) and the performance of the immunosensor was studied by differential pulse voltammetry (DPV) measurements. To improve the analytical characteristics of the immunosensor, the experimental conditions were optimized. The immunosensor exhibited a good response to ferritin in ranges from 1.0 to 5.0 and 5.0 to 120.0 ng mL⁻¹ with a detection limit of 0.4 ng mL⁻¹. The fabricated immunosensor could make a low-cost, sensitive, quantitative detection of ferritin, and would have a potential application in clinical immunoassays.