Experimental study on the influence of surfactant foam properties on the slow release of gas in coal

In the process of mining coal resources, the abnormal emission of gas associated with coal may lead to serious gas overrun, and trigger problems such as gas disaster or greenhouse effect. Many studies have shown that injecting surfactant solutions into coal seam is one of the effective and important means of gas management. Surfactant mixed with gas is easy to form stable foam. However, there are few studies on the influence of foam properties on gas desorption. Therefore, this paper studied the influence of surfactant foam properties on the slow release law of gas. Two surfactants, sodium dodecyl benzene sulfonate (SDBS) and alkyl glycoside (APG0810), were selected to test the surface tension, viscosity, foaming, stability and foam morphology of solutions. The effects of surfactant foam properties on gas release was investigated using a self-developed experimental apparatus. The experimental results shown that with the increase of surfactant mass fraction, the surface tension of liquid decreased greatly at first, the foaming rate increased obviously, and the foaming stability increased gradually. When approaching the critical micelle concentration, the decrease amplitude of surface tension slowed down, and the foaming and foaming stability increased gently. At a mass fraction of 0.15%, the foaming heights of SDBS and APG0810 after air injection were 44 mm and 40 mm, respectively, and the maximum half-life of SDBS foam was 786.5 s. The slow release effect of solution foam on gas was well correlated with its foaming rate and half-life. At the same mass fraction, SDBS was generally better than APG0810 in the slow release of gas. At a mass fraction of 0.15%, the gas slow release rate of APG0810 and SDBS within 10 min were about 37.4% and 12.7%, respectively, and that of SDBS within 2 h was still about 50.84%. This study can provide a new perspective to investigate the inhibition and its mechanism of gas desorption in coal by surfactants, and also a certain theoretical support for the prevention and control of gas in mines and the green mining of coal

Experimental study on the influence of middle and low rank coal functional groups on coal wettability

Coal seam water injection can effectively inhibit gas gushing in the process of coal mining, and its inhibition effect mainly depends on the wetting characteristics of coal seam. The chemical structure of coal is one of the important factors affecting the wettability of coal. In order to study the relationship between the functional groups of medium and low rank coal and its wettability, the coal quality characteristics of typical medium and low rank coal samples were analyzed, and the parameters of different coal samples were obtained by Nicolet iN10 Fourier Transform microscopic infrared spectrometer. In this paper, the size of the contact Angle of deionized water at the solid-liquid-gas junction on the coal surface is used to characterize the wettability of coal. JC2000D contact Angle measuring instrument is used to obtain the contact Angle of different coal samples. Zeta potential can reflect wettability and ionization degree of coal surface functional groups, so as to establish the relationship between hydrophilic functional groups (hydroxyl functional groups, other oxygen-containing functional groups), contact Angle and Zeta potential of coal samples. The experimental results show that with the deepening of coal metamorphism, the strength of hydrophilic functional groups of coal samples decreases gradually, the peak height of hydrophilic functional groups of middle rank coal decreases by 0.13 compared with that of low rank coal, and the absorption peak area decreases by 58.91. The hydrophilic functional groups are negatively correlated with the contact Angle of coal samples, that is, the contact Angle decreases gradually with the increase of absorption peak intensity of hydrophilic functional groups, and the contact Angle decreases by 8.27 ° from middle rank coal samples to low rank coal samples. The relationship between hydrophilic functional groups and Zeta potential of coal samples shows a first-order exponential decay function, and the correlation coefficient is as high as 0.95. That is to say, the absolute value of Zeta potential increases gradually with the increase of absorption peak area of hydrophilic functional groups. The surface electronicity of coal samples is strong, and the hydrophilicity of coal is good. Among them, the hydroxyl functional group has a great influence on the wettability of coal, and the hydrogen bond formed by self-associating hydroxyl group is the main factor affecting the wettability of coal. Other oxygen-containing functional groups, such as carboxyl and ether bond hydrophilic functional groups, combine with water molecules under intermolecular force, showing strong vitality and improving the hydrophilicity of coal

The impact of the atmospheric turbulence-development tendency on new particle formation : a common finding on three continents

A new mechanism of new particle formation (NPF) is investigated using comprehensive measurements of aerosol physicochemical quantities and meteorological variables made in three continents, including Beijing, China; the Southern Great Plains site in the USA; and SMEAR II Station in Hyytiala, Finland. Despite the considerably different emissions of chemical species among the sites, a common relationship was found between the characteristics of NPF and the stability intensity. The stability parameter (zeta = Z/L, where Z is the height above ground and L is the Monin-Obukhov length) is found to play an important role; it drops significantly before NPF as the atmosphere becomes more unstable, which may serve as an indicator of nucleation bursts. As the atmosphere becomes unstable, the NPF duration is closely related to the tendency for turbulence development, which influences the evolution of the condensation sink. Presumably, the unstable atmosphere may dilute pre-existing particles, effectively reducing the condensation sink, especially at coarse mode to foster nucleation. This new mechanism is confirmed by model simulations using a molecular dynamic model that mimics the impact of turbulence development on nucleation by inducing and intensifying homogeneous nucleation events.Peer reviewe

Berberine Improves Glucose Metabolism in Diabetic Rats by Inhibition of Hepatic Gluconeogenesis

Berberine (BBR) is a compound originally identified in a Chinese herbal medicine Huanglian (Coptis chinensis French). It improves glucose metabolism in type 2 diabetic patients. The mechanisms involve in activation of adenosine monophosphate activated protein kinase (AMPK) and improvement of insulin sensitivity. However, it is not clear if BBR reduces blood glucose through other mechanism. In this study, we addressed this issue by examining liver response to BBR in diabetic rats, in which hyperglycemia was induced in Sprague-Dawley rats by high fat diet. We observed that BBR decreased fasting glucose significantly. Gluconeogenic genes, Phosphoenolpyruvate carboxykinase (PEPCK) and Glucose-6-phosphatase (G6Pase), were decreased in liver by BBR. Hepatic steatosis was also reduced by BBR and expression of fatty acid synthase (FAS) was inhibited in liver. Activities of transcription factors including Forkhead transcription factor O1 (FoxO1), sterol regulatory element-binding protein 1c (SREBP1) and carbohydrate responsive element-binding protein (ChREBP) were decreased. Insulin signaling pathway was not altered in the liver. In cultured hepatocytes, BBR inhibited oxygen consumption and reduced intracellular adenosine triphosphate (ATP) level. The data suggest that BBR improves fasting blood glucose by direct inhibition of gluconeogenesis in liver. This activity is not dependent on insulin action. The gluconeogenic inhibition is likely a result of mitochondria inhibition by BBR. The observation supports that BBR improves glucose metabolism through an insulin-independent pathway

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Adsorption Mechanism of Lignosulfonate at the Air/Liquid Interface

<div><p>Lignosulfonate is a type of natural polymer surfactant. Its capability to reduce the surface tension of aqueous solution depends on its adsorption configuration at the air/liquid interface. The dynamic surface tension, the air/liquid interfacial film properties of lignosulfonate at different solution concentrations, pH values and ionic strengths had been measured in the present work. The results showed that the adsorption equilibrium of lignosulfonate at the air/liquid cannot be achieved in a short period; the diffusion coefficient of lignosulfonate from the liquid to the air/liquid interface decreased with the increasing of pH value, while it increased with the increasing of ionic strength. Lignosulfonate could form soluble monomolecular film at the air/liquid interface, whereas the film was unstable. The stability of lignosulfonate monomolecular film became poor with the increasing of solution concentration, ionic strength and decreasing of pH value. Combining with our previous research results, the adsorption mechanism of lignosulfonate at the air/liquid interface was proposed.</p></div

Interactions of Bromocarbazoles with Human Serum Albumin Using Spectroscopic Methods

The 1,3,6,8-tetrabromocarbazole and 3-bromocarbazole have attracted great attention in the ecotoxicology field recently as hazardous environmental contaminants. In this study, the quenching mechanism of these two substances binding with human serum albumin (HSA) has been investigated with spectroscopic methods. Through fluorescence quenching and binding site experiments with steady-state fluorescence and UV-Vis spectra, the intrinsic fluorescence of HSA quenched by 1,3,6,8-tetrabromocarbazole and 3-bromocarbazole both in static process, are activated by binding to site II (subdomain IIIA) of the HSA. In addition, it was not only found that the conformation and secondary structure of the proteins changes, but also that their spontaneous binding processes were driven by electrostatic interactions as well as hydrophobic forces for HSA-1,3,6,8-tetrabromocarbazole, and by typical hydrophobic forces for HSA-3-bromocarbazole. The above studies are beneficial to enhance our understanding of the ecotoxicology and environmental behaviors of halogenated carbazoles

Combining appearance and structural features for human action recognition

In this paper, we propose to integrate structural information with appearance features for human action recognition. In local representations based on detected spatio-temporal interest points (STIPs), the layout of STIPs carries important cues of motion structures in video sequences, and is assumed to contain complementary information to appearance features. We aim to incorporate structures into the description of STIPs by combing with appearance features for action representation. Based on the previous work of the 3D shape context, we present an optimised version of 3D shape context to encode the layout information of STIPs. By combining the proposed optimised 3D shape context with appearance descriptors, e.g., HOG3D and 3D gradients, we provide a more informative and discriminative description of STIPs for action classification. To validate the proposed descriptor, we have conducted extensive experiments on the KTH and the UCF YouTube datasets. The results prove that the optimised 3D shape context offers complementary information to appearance features, showing its effectiveness for action representation; moreover, the proposed descriptor yields comparable results with the state-of-the-art methods