Accuracy improvement on quantitative analysis of the total iron content in branded iron ores by laser-induced breakdown spectroscopy combined with double back propagation artificial neural network

The rapid and accurate quantitative analysis of total iron (TFe) content in iron ores is extremely important in global iron ores trade. Due to the matrix effect among iron ores...

Changes in gaseous concentration of alkylpyrazine analogs affect mouse avoidance behavior

The Y-maze is often used to detect subtle differences between similar odor sources; however, very little information is available about the dispersion of odor plumes in the Y-maze. Using headspace solid-phase microextraction (HS-SPME) in conjunction with a GC-MS system, we quantified alkylpyrazine analogs in the Y-maze. Rapid extraction of volatile compounds in the vapor phase enabled accurate quantitative analysis of temporal changes in the levels of gaseous alkylpyrazine analogs at several locations in the Y-maze. We conducted behavioral tests of mice in response to these volatiles and identified a positive relationship between the rate of increase in gaseous concentration and the induced avoidance rate. Our results demonstrate that the Y-maze is a simple but reliable apparatus for behavioral studies of olfaction. Our findings show that the HS-SPME fast extraction method could quantify how gaseous concentrations of alkylpyrazine analogs change over time, and that temporal increases in alkylpyrazine concentration were correlated with induction of aversive behavior in mice.

APPLICATION OF MICROCOLUMN HPLC-UV FOR RAPID QUANTITATIVE ANALYSIS OF ARBUTIN, BERGEN-IN AND GALLIC ACID IN BERGENIA CRASSIFOLIA

This work is aimed at the development of a microcolumn HPLC-UV assay for the rapid quantitative analysis of arbutin, bergenin, and gallic acid in Bergenia crassifolia. The results obtained indicate appropriate metrological parameters of the developed assay. It was found that the known methods of quantitative analysis of phenolic glycosides using SPE-spectrophotometry cannot be characterized as selective and accurate, due to the fact that the presences of the impurity compounds that do not belong to the group of phenolic glycosides negatively influenced the results. The developed assay was used for quantitative analysis of wild and commercial samples of B. crassifolia raw material. It was found that the content of arbutin, bergenin, and gallic acid in samples of B. crassifolia rhizomes collected in the Republic of Buryatia was 38.58–45.97, 66.74–139.76 and 1.22–1.65 mg/g, respectively, and for commercial batches of raw materials 20.57–41.37, 35.04–83.94 and 0.22–1.28 mg/g, respectively. It was found that the process of gradual enzymatic changes in the color of B. crassifolia leaves (green, red, black) leads to significant changes in the chemical composition. The most pronounced phenomenon is the degradation of bergenin, the presence of which is noted only in green leaves. The concentration of gallic acid is reduced in black leaves. Arbutin is characterized by an increased content in red leaves (102.02 mg/g). Additionally, a quantitative analysis of the peduncles and flowers of B. crassifolia was realized, and it was shown that they are distinguished by a high content of arbutin 48.40 and 42.15 mg/g, respectively, as well as bergenin in flowers (16.89 mg/g). The study demonstrated that the developed technique can be applied for a quick, selective, and accurate quantitative analysis of three compounds in various organs of B. crassifolia.

A Damage Constitutive Model of Rock Subjected to Freeze-Thaw Cycles Based on Lognormal Distribution

The constitutive model of rock is closely connected with the mechanical properties of rock. To achieve a more accurate quantitative analysis of the mechanical properties of rock after the action of freeze-thaw cycles, it is necessary to establish the constitutive models of rock subjected to freeze-thaw cycles from the view of rock damage. Based on the assumption of rock couple damage, this study established a statistical damage constitutive model of rock subjected to freeze-thaw cycles by combining the lognormal distribution, which is commonly used in engineering reliability analysis, and the strain strength theory. Then, the coordinates and derivative at the peak of the stress-strain curve of the rock after the action of freeze-thaw cycles were obtained through experiments to solve the statistical distribution parameters με and S of the model, whereafter, the theoretical curves by the established model were compared with the experimental curves to verify the validity of it, which shows a great agreement. Finally, the sensitivity analysis of the statistical distribution parameters was implemented. The results indicate that με reflects the strength of the rock, which shows a positive relation, and S stands for the brittleness of the rock, which shows a negative relation.

Individual separation of surface, bulk and Begrenzungs effect components in the surface electron energy spectra

We present the first theoretical recipe for the clear and individual separation of surface, bulk and Begrenzungs effect components in surface electron energy spectra. The procedure ends up with the spectral contributions originated from surface and bulk-Begrenzungs excitations by using a simple method for dealing with the mixed scatterings. As an example, the model is applied to the reflection electron energy loss spectroscopy spectrum of Si. The electron spectroscopy techniques can directly use the present calculation schema to identify the origin of the electron signals from a sample. Our model provides the possibility for the detailed and accurate quantitative analysis of REELS spectra.

Research on Effectiveness Evaluation Method of Weapon Equipment

Due to the wide application of high and new technology in weapons and equipment, modern weapons present the characteristics of complexity and systematization, and their effectiveness analysis and evaluation are paid more and more attention, which has become an arduous and urgent task in the research of weapon equipment system. Only by using scientific methods and technology to evaluate the effectiveness of various types of weapons and equipment, can we have a profound understanding of the characteristics and application value of weapons and equipment, ensure that the army can give full play to the operational potential of weapons and equipment, improve the operational efficiency, and explore the correct direction of the construction and development of weapons and equipment. Therefore, systematic research on weapon equipment effectiveness evaluation method is a necessary way for every military equipment effectiveness researcher to seek effective and accurate quantitative analysis of weapon equipment effectiveness method.

Selection of an Optimal Abrasion Wheel Type for Nano-Coating Wear Studies under Wet or Dry Abrasion Conditions

Nanocoatings have numerous potential applications in the indoor environment, such as flooring finishes with increased scratch- and wear-resistance. However, given concerns about the potential environmental and human health effects of nanomaterials, it is necessary to develop standardized methods to quantify nanomaterial release during use of these products. One key choice for mechanical wear studies is the abrasion wheel. Potential limitations of different wheels include the release of fragments from the wheel during abrasion, wearing of the wheel from the abrasion process, or not releasing a sufficient number of particles for accurate quantitative analysis. In this study, we evaluated five different wheels, including a typically used silicon oxide-based commercial wheel and four wheels fabricated at the National Institute of Standards and Technology (NIST), for their application in nanocoating abrasion studies. A rapid, nondestructive laser scanning confocal microscopy method was developed and used to identify released particles on the abraded surfaces. NIST fabricated a high performing wheel: a noncorrosive, stainless-steel abrasion wheel containing a deep cross-patch. This wheel worked well under both wet and dry conditions, did not corrode in aqueous media, did not release particles from itself, and yielded higher numbers of released particles. These results can be used to help develop a standardized protocol for surface release of particles from nanoenabled products using a commercial rotary Taber abraser.

Precision Auto-Focusing Apparatus Based on Long-Working-Distance, Wide-Spectrum Microscope

A mirror-based Schwarzschild microscope with a wide spectrum and a long working distance was investigated to perform precise assemblage of detectors. We employed a gradient square method to construct the evaluation function for realizing accurate quantitative analysis of image defocusing. By imaging a resolution target that corresponded to 228 line pairs per mm, the validity and imaging ability of the system was proven. The results of repeated focusing tests yielded a standard deviation of 0.75 μm, which indicated high performance accuracy for the focusing system. The proposed system has potential applications in industrial inspection and focusing detection.