Mingyin Yao

Detection of chromium in wastewater from refuse incineration power plant near Poyang Lake by laser induced breakdown spectroscopy

A laser induced breakdown spectroscopy (LIBS) system was developed for determination of toxic metals Cr in wastewater collected from a refuse incineration power plant near Poyang Lake. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on the surface of liquid. Experimental conditions were optimized for improving the sensitivity and repeatability of the LIBS system through a parametric dependence study in potassium bichromate (K(2)Cr(2)O(7)) aqueous solutions. Calibration curves for Cr I 425.43 and 357.87 nm lines are compared and the limit of detection is found to be 39 and 86 ppm, respectively. This calibration curve of Cr I 425.43 nm has been used for quantification of Cr in wastewater collected from a refuse incineration power plant near Poyang Lake where the concentration of Cr is found to be 97 ppm. The results between LIBS and standard analytical technique such as atomic absorption spectroscopy were compared, and the relative standard deviation was 8.5%.

Study on Image Recognition of Insect Pest of Sugarcane Cotton Aphis Based on Rough Set and Fuzzy C-means Clustering

Sugarcane cotton aphis is a common insect pest in China. Rough set and fuzzy C-means clustering were applied to identify the insect pest of sugarcane cotton aphis. Rough set was used to obtain the characteristic parameters of identify insect pest of sugarcane cotton aphis. Then, fuzzy C-means clustering was used to extract the regions of the insect pest of sugarcane cotton aphis. The experimental results showed that 17 images were segmented correctly and the accurate rate of the segmentation was 85%.

Identification of Nutrition Elements in Orange Leaves by Laser Induced Breakdown Spectroscopy

Laser induced breakdown spectroscopy (LIBS) has been used for the determination of the species and concentration of elements in industries. However, there is less research for LIBS analysis of agricultural and environmental samples. In this work, a LIBS system has been evaluated for the determination of nutrition elements in orange leaves. The experimental setup was designed by using a Nd:YAG laser operating at 1064 nm (200 mJ per pulse and 5HZ repetition rate) and an Avantes spectrometer (200-1100nm wavelength range)with ICCD detector. The species and relative contents were identified by LIBS spectra, which belonged to qualitative analysis. The quantitive analysis will be carried combining with routine analysis such as ICP-OES.

Detection of heavy metal Cd in polluted fresh leafy vegetables by laser-induced breakdown spectroscopy

In seeking a novel method with the ability of green analysis in monitoring toxic heavy metals residue in fresh leafy vegetables, laser-induced breakdown spectroscopy (LIBS) was applied to prove its capability in performing this work. The spectra of fresh vegetable samples polluted in the lab were collected by optimized LIBS experimental setup, and the reference concentrations of cadmium (Cd) from samples were obtained by conventional atomic absorption spectroscopy after wet digestion. The direct calibration employing intensity of single Cd line and Cd concentration exposed the weakness of this calibration method. Furthermore, the accuracy of linear calibration can be improved a little by triple Cd lines as characteristic variables, especially after the spectra were pretreated. However, it is not enough in predicting Cd in samples. Therefore, partial least-squares regression (PLSR) was utilized to enhance the robustness of quantitative analysis. The results of the PLSR model showed that the prediction accuracy of the Cd target can meet the requirement of determination in food safety. This investigation presented that LIBS is a promising and emerging method in analyzing toxic compositions in agricultural products, especially combined with suitable chemometrics.

Determination of heavy metal chromium in pork by laser-induced breakdown spectroscopy

Meat can be polluted by heavy metals during the feeding of livestock and processing of meat. It is necessary to monitor the concentration of toxic metals in meat. The element chromium (Cr) in pork was selected as a determination target for this work. Fresh pork was polluted in a Cr solution to create a different content level, then dried and pressed into pellets to eliminate the effect of water and improve the stability and sensitivity of laser-induced breakdown spectroscopy (LIBS). The spectra of pressed pellets were collected at optimized LIBS experimental parameters. After that, the real content of samples was obtained by atomic absorption spectroscopy. Characteristic lines Cr I 425.43, Cr I 427.48, and Cr I 428.97 were verified, and a model comparing the LIBS intensity of the line peak and the actual concentration of Cr was constructed. The results showed that the model has better predicted precision and accuracy, especially applying the line Cr I 425.43 for calibration. This work makes it obvious that LIBS has food safety potential for detecting residue of heavy metals in meat.

Analysis of Trace Elements in Leaves Using Laser-Induced Breakdown Spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) is a new way to analyze the plant ecology. The experimental used a Q-switched Nd:YAG laser to be the laser source and equipped with an eight-channel model spectrometer which’s wavelength range between 200 and 1100 nm. Studying the spectrum of the air-drying leaves and the nature leaves and detected the elements which contain Fe, Ca, Na, Mg, K, Cu, Al and Mn. Displaying the list which shows the all spectrum and elements. Refer to Fe as the benchmark, obtain the relative content of trace elements. At the same time, this technology can be employed for food safety and environment pollution evaluation. It will be the based for studying the portable LIBS instrument of detecting the pollution of heavy metal.

Application of BP Neural Network to Sugarcane Diseased Spots Classification

Red rot disease and ring spot disease are two common diseases at the seedling stage of sugarcane. According to the image characteristics of diseased spots, sugarcane diseased spots classification using BP neural network is proposed. Firstly, the feature parameter combination of mean value of color component Cr, mean value of color component V and roundness is selected as the feature parameters of the following pattern recognition by orthogonal experiment design method. Then, BP neural network with 3 input neurons, 12 hidden neurons and 1 output neuron is constructed to distinguish between red rot diseased spots and ring spot diseased spots. The experimental results show that recognition accurate rates of rough set, fuzzy K near neighbor algorithm and BP neural network are 86%, 91% and 94%, respectively. BP neural network is more suitable to distinguish between the two diseased spots than fuzzy K near neighbor algorithm and rough set.

Analysis the macronutrients in Gannan navel oranges for three kinds of sample state by laser induced breakdown spectroscopy

By detecting the nutrient elements intensity in Gannan navel oranges for analysis the difference among the three states and the reasons, the K, Ca, and Na elements have been analyzed by laser induced breakdown spectroscopy (LIBS) technique, which is made up with a Nd:YAG ns laser at 1064 nm and an eight-channel Ava-Spec spectrometer with CCD detector and optical devices. The absolute and relative intensity of characteristic spectra for K, Ca, Na were obtained that can find out that the powdery orange peel intensity is more than fresh orange peel, and lager than digestion liquid for the same analytical spectra, Also a different intensity for different analytical spectra in the same element and for a diverse element in the same condition, which is due to the moisture content, the state of matter and the compactness. It is also indicated that LIBS technique will be a rapid and effective method for quantitative analysis of nutrient elements in matter by the relative intensity or normalized intensity.

Comparison between Fertilization N, P, K and No Fertilization N, P, K in Paddy Soil by Laser Induced Breakdown Spectroscopy

By detecting the nutrient elements contents in soil for monitoring the rice growth and conditions of nutrients, a month after fertilization N, P, K and no fertilization in paddy soil have been analyzed by laser induced breakdown spectroscopy (LIBS) technique, which is using a Nd: YAG ns laser at 1064 nm and an eight-channel AvaSpec spectrometer with CCD detector. The characteristic spectra and the relative intensity of N, P, K were obtained that can find out the line intensity of fertilization smaller than no fertilization in soil for the three elements. Comparing the rice growth situations of two, it is very useful for monitoring the absorption of plant to nutrients, guiding the fertilization for soil and predicting the rice growth to detect the concentrations of essential elements by LIBS. It is also indicated that LIBS technique is a rapid and effective method for detecting and comparing the contents of nutrient elements in paddy soil.

Analysis of Cr in the Water of Poyang Lake by Laser-Induced Breakdown Spectroscopy

Based on the complexities within the natural water, heavy metal element Cr in K₂Cr₂O₇ solution and the treated water of Poyang Lake are both detected in this paper by laser-induced breakdown spectroscopy (LIBS). Compared with the K₂Cr₂O₇ solution, the better trigger frequency with less interference from other ions or impurities in the detection of PoYang Lake water is available. And the best frequency in detection of Poyang Lake water is 1Hz when taken Cr I at 425.43nm, 427.48nm and 428.97nm into consideration, while the best frequency for detecting K₂Cr₂O₇ solution is 2Hz. However, the linear regression correlation coefficients in the analysis of Cr at 425.43nm in K₂Cr₂O₇ solution and the treated water are both high under the frequency of 1Hz. It demonstrates that a better multivariate combination can be done to improve the use of LIBS in the determination of complex material for broadening the spectral detection range of target element or the detected objects.