Rapid determination of illegal additives chrysoidin and malachite green by surface-enhanced Raman scattering with silanized support based substrate

Silanized support based SERS substrate is applied to detect chrysoidin in Sprite at 0.01 mg/L and malachite green in fish pond water at 0.0001 mg/L. The SERS method is sensitive, cost-effective and convenient, which has great potential in detection of illegal additives and harmful substances.     

膜富集-可见漫反射光谱法测定池塘水和维生素B_(12)药片中痕量钴

1-(2-吡啶偶氮)-2-萘酚与钴离子生成暗绿色的络合物,反应后将其过滤到膜上,测得膜表面漫反射光谱,据此提出了膜富集-可见漫反射光谱法测定池塘水和维生素B12药片中痕量钴的方法。钴的质量浓度在0.2~3.0μg·L-1和3.0~10.0μg·L-1范围内与其吸光度呈线性关系,检出限(3s/k)为0.093μg·L-1。方法用于池塘水和维生素B12药片的分析,加标回收率在96.7%~105%之间,测定值的相对标准偏差在1.4%~2.9%之间。     

New analytical solutions for nonlinear physical models of the coupled Higgs equation and the Maccari system via rational exp <Emphasis Type="BoldItalic">(−φ(η))</Emphasis>-expansion method

In this article, a variety of solitary wave solutions are found for some nonlinear equations. In mathematical physics, we studied two complex systems, the Maccari system and the coupled Higgs field equation. We construct sufficient exact solutions for nonlinear evolution equations. To study travelling wave solutions, we used a fractional complex transform to convert the particular partial differential equation of fractional order into the corresponding partial differential equation and the rational exp (?φ(η))-expansion method is implemented to find exact solutions of nonlinear equation. We find hyperbolic, trigonometric, rational and exponential function solutions using the above equation. The results of various studies show that the suggested method is very effective and can be used as an alternative for finding exact solutions of nonlinear equations in mathematical physics. A comparative study with the other methods gives validity to the technique and shows that the method provides additional solutions. Graphical representations along with the numerical data reinforce the efficacy of the procedure used. The specified idea is very effective, pragmatic for partial differential equations of fractional order and could be protracted to other physical phenomena.     

Stagnation-point flow of couple stress fluid with melting heat transfer

Melting heat transfer in the boundary layer flow of a couple stress fluid over a stretching surface is investigated. The developed differential equations are solved for homotopic solutions. It is observed that the velocity and the boundary layer thickness are decreasing functions of the couple stress fluid parameter. However, the temperature and surface heat transfer increase when the values of the couple stress fluid parameter increase. The velocity and temperature fields increase with an increase in the melting process of the stretching sheet.     

Ultra sensitive surface‐enhanced Raman scattering detection based on monolithic column as a new type substrate

A novel ultrasensitive detection method utilizing surface‐enhanced Raman scattering (SERS) based on monolithic column was developed in the present study. Monolithic column is a kind of chromatographic stationary phase that contains highly interconnected pores and absorbs chemical components efficiently. Dropping a mixture solution containing analyte, silver colloid, and NaCl on the surface in advance, SERS signals were collected on the surface of the monolithic column. With this method, five commonly used probe molecules of Rhodamine 6G (R6G), p‐aminothiophenol, Rhodamine 123, crystal violet, thymine, and two chemicals that are used in agriculture (paraquat and flusilazole) were detected. Especially, R6G and p‐aminothiophenol can be detected at extremely low concentrations of 10^–18 and 10^–16 mol/L at milliliter level, respectively. The enhancement factor was calculated to be approximately 10¹⁴ for R6G detection. The results suggest that the monolithic column does improve the sensitivity of SERS detection dramatically and the topography of the monolithic column is essential for the enhancement. The easy operability and the significant enhancement are the greatest advantages of this method. Copyright © 2012 John Wiley & Sons, Ltd.     

Calibration transfer of near‐infrared spectra for extraction of informative components from spectra with canonical correlation analysis

A new calibration transfer method that applies canonical correlation analysis (CCA) to transfer the informative components extracted from a spectral dataset is proposed to reduce the interference of noise, background and non‐predicted properties. This method employs the partial least squares method to extract the informative components related to the predicted properties from the raw spectra and then corrects the informative components based on CCA. The performance of this algorithm was tested using three pairs of spectra batches: two pairs of corn spectra and one pair of tri‐component solvent spectra. The results showed that this method can significantly reduce prediction errors compared with CCA and piecewise direct standardization. Copyright © 2014 John Wiley & Sons, Ltd.     

Ultra-sensitive spectrophotometric determination of nickel after complexation and membrane filtration

We report on a simple, sensitive and selective method for the spectrophotometric determination of Ni²⁺ in water samples. The analyte ions were collected on a membrane filter in the form of their red complex with 1-(2-pyridylazo)-2-naphthol (PAN), and the absorption spectra of the colored membrane filters were acquired. Effects of pH value, sample volume, and amount of PAN were examined in order to optimize sensitivity. The interference by common other ions was eliminated using appropriate masking agents. The absorbance is linearly related to the concentration of Ni²⁺ in the ranges from 0.3 to 1.5 μg L^?1, and from 2 to 10 μg L^?1, respectively, the correlation coefficients (R²) being 0.9871 and 0.9954. Under the optimal conditions, the detection limit is 0.1 μg L^?1. The recoveries in case of spiked samples are between 95.0% and 101.5%, and the relative standard deviations range from 2.8% to 4.1%.

Vibrational spectroscopy of selective dental restorative materials

Recently, significant advancement has occurred in vibrational (Fourier transform infrared [FTIR] and Raman) spectroscopy associated with dental materials. FTIR and Raman spectroscopies have emerged as significant breakthrough techniques and offer exciting new possibilities in the area of dental materials. These techniques have been used to obtain chemical images of formulations and allow researchers to find out the in situ structure of materials. This review summarizes the information obtained from these two techniques and their application in dental material sciences. The presented database of vibrational spectroscopy facilitated the appropriate identification of frequently used dental materials ranging from filling, obturating, adhesive, lining/luting materials, and prosthodontics materials. Spectral peaks that are related to these materials are discussed in detail, which provided crucial data in understanding the chemical structural properties. The application of vibrational spectroscopy allowed for a quick differential identification of typical dental materials composed of organic and inorganic compounds. From our study as well as the literature reviewed, it appeared that investigators uniformly confirmed the benefits of vibrational spectroscopy concerning identification of chemical functional groups of different chemical compositions. The diagnostic and prognostic tools based on these technologies have the potential to revolutionize our concepts leading to improve materials sciences and clinical application.