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Feature extraction is an important part for coal and gangue recognition, which has direct impact on accuracy of recognition. However, the existing feature extraction methods for coal and gangue are not ideal, and so a feature extraction method with multi-fractal is proposed based on energy field normalization for target recognition of coal and gangue in this paper. In the method, the concept of target energy field is established based on 3D grey surface, and the normalized target energy is calculated by using pixels. Then, after analysis of the feature extraction process, a feature extraction algorithm with multi-fractal is proposed based on energy field, in which 3D grey surface is divided by different grid forms, and the pixels in grid are counted to obtain the probability density distribution matrix of pixels. The results of multiple feature extraction is observed visually from probability density distribution, spatial feature distribution, and multi-fractal spectrum to illustrate the measurability of the method for target textures, which is the quantitative attribute of feature extraction. In the experiment, this method is used to quantitatively measure grey texture, and the effectiveness of measured features in coal and gangue recognition is compared with other methods. The experiment results show that the method can achieve effective quantitative measurement for coal and gangue texture, and the recognition accuracy is higher than other methods. [ABSTRACT FROM AUTHOR]

This study demonstrates a method to quantitatively measure the oleophobicities of food packaging paper via using a tracer‐assisted headspace gas chromatography by adding a 40‐μL droplet of toluene‐doped oil onto a sample surface, wherein toluene behaves as volatile tracer. After 20 s, the sample was turned vertically to remove the oil and placed in a headspace vial. The amount of toluene in the residual oil adhered to the sample surface was quantified using headspace gas chromatography under full‐evaporation conditions. The results exhibit satisfactory precision (RSDs < 2.5%) and provide quantitative information on oleophobicity. The proposed method is simple, efficient and suitable for batch sample testing. [ABSTRACT FROM AUTHOR]

The present work reports on a method for the determination of hydrophobic degree of paper packaging material by tracer-assisted headspace gas chromatography. The method was based on adding 40 μL of methanol-water drop on the paper surface for 20 s. After removing the excess water by turning the sample vertically, the sample is placed in a vial and the amount of residual tracer attached on the material surface was accurately quantified by full evaporation headspace gas chromatography. The results show that the present method has a good precision (less than 4.1 %). The present method is simple and accurate and it can be an efficient tool for testing the hydrophobic degree of paper packaging material in batch. [ABSTRACT FROM AUTHOR]

Abstract: We report a simple and automated headspace gas chromatographic technique for the determination of the softening point of rosin. A lumpy solid of rosin is added into a headspace vial, then an automated stepwise temperature ramping and headspace sampling was performed at each temperature stage and gas chromatography measurement. By plotting the gas chromatography signal for an impurity in rosin versus the temperature, a transition point (corresponding to the rosin softening point) was determined. The results show that the present method has a good precision (<0.76%), and good accuracy (the relative differences compared to the ring and ball method was <4.0%). The present method is simple, accurate, and automated. It is practical and suitable for testing the softening of rosin and derivatives in mills. [ABSTRACT FROM AUTHOR]

Two new chromones, fistulachromones A and B ( 1 and 2), together with three known chromones ( 3- 5), were isolated from the twigs of Cassia fistula. Their structures were determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1 and 2 were tested for their anti-tobacco mosaic virus (anti-TMV) activities. Compounds 1 and 2 showed high anti-TMV activities with inhibition rates of 27.5 and 30.8%, respectively. These rates are close to that of positive control. [ABSTRACT FROM AUTHOR]

Two new prenylated isocoumarins, versicolols C and D ( 1 and 2), together with three known isocoumarins ( 3- 5), were isolated from the fermentation products of the endophytic fungus Aspergillus versicolor. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. The anti-tobacco mosaic virus (anti-TMV) activities of compounds 1 and 2 were evaluated. The results revealed that compounds 1 and 2 showed moderate anti-TMV activity with inhibition rates of 22.4 and 24.6%, respectively. [ABSTRACT FROM AUTHOR]

Phytochemical investigations on the ethanol extract of the twigs of Garcinia tetralata resulted in the isolation of three new biphenyls, tetralatabiphenyls A–C (1–3), along with three known biphenyl derivatives (4–6). Structural elucidations of 1–3 were performed by spectroscopic methods such as 1D and 2D NMR spectra, in addition to high-resolution mass spectra. Compounds 1–6 were also evaluated for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compound 3 showed high anti-TMV activity with inhibition rate of 31.1%. Compounds 1, 2, and 4–6 also showed modest anti-TMV activities with inhibition rates in the range of 18.9–24.5%, respectively. [ABSTRACT FROM AUTHOR]

We present a passively Q-switched Yb:KGW laser based on a transmission-type saturable absorber of topological insulator: Bi2Se3. The saturable absorber is prepared on a 0.17-mm glass substrate and can translate intra-cavity for best performance nearly without influence on the laser mode. At a maximum pump power of 13.7 W, the central wavelength, pulse duration, repetition rate, and pulse energy of Q-switched pulse are 1043 nm, 1.5 μs, 175.4 kHz, 6.39 μJ, respectively. The maximum output power is 1.12 W. To our knowledge, this is the highest average output power from passively Q-switched lasers with topological insulator saturable absorbers. [ABSTRACT FROM AUTHOR]

We demonstrate the first use of single layer graphene for compressing self-Q-switching pulses in semiconductor disk lasers. The gain region of the semiconductor disk laser used InGaAs quantum wells with a central wavelength of 1030 nm. Due to self saturable absorption of the quantum wells, the disk laser emitted at the self-Q-switching state with a pulse width of 13 μs. By introducing the single layer graphene as a saturable absorber into the V-shaped laser cavity, the pulse width of the self-pulse was compressed to 2 μs with a lower pump power of 300 mW. As the pump power was increased, multiple pulses with the pulse width of 1.8 μs appeared. The compression factor was about 7.2. [ABSTRACT FROM AUTHOR]