Comprehensive characterization of shale gas seepage in nanoscale organic-rich shales

Unlike conventional gas reservoirs, the shale gas resources are widely distributed in organic-rich shale formations with most pore sizes down to nanoscale. Such nanoscale confinement has invalidated the conventional gas transport mechanisms which are characterized by the Navier-Stokes equations. A common practice in shale reservoir simulation, which arbitrarily increases intrinsic matrix permeability to match the production data, has been proven inefficient and unreliable. This research work aims to bridge the gap in scientific understanding of the shale gas transport across the hierarchical structures of organic-rich matrix by developing different analytical and numerical models which incorporate various mechanisms in shale formations. More specifically, this work explores the qualitative and quantitative influences of the rarefaction effect, real gas effect, multilayer adsorption, surface diffusion, nano-confinement effect, and pore-structure heterogeneity on the shale gas flow. First, a new unified gas transport model is developed by modifying Bravo’s model to describe the rarefaction which is commonly in presence in nanopores. Particularly, a straight capillary tube is characterized by a conceptual layered model consisting of a viscous flow zone, a Knudsen diffusion zone, and a surface diffusion zone. To specify the contributions of the viscous flow and the Knudsen diffusion, the virtual boundary between the viscous flow and Knudsen diffusion zones is firstly determined based on Kennard’s analytical kinetics approach. Then, the model considers the real gas effect, multilayer adsorption and nano-confinement effect to quantify the density oscillation and phase behavior in confined nanopores. Meanwhile, the apparent permeability (AP) model is analytically derived and numerically simulated at core-scale. In addition, the field scale production rate is numerically calculated by coupling the nanoscale mechanisms. Furthermore, the pore-structure heterogeneity impact on production rate is studied by the fuzzy statistical method in which the Monte Carlo simulation is implemented for the sensitivity analyses of the structural parameters in the fractal model. The proposed analytical model has been successfully validated against molecular dynamic simulation and experimental flux results for five types of gases (i.e., methane, nitrogen, helium, argon, and oxygen) with the assistance of optimization methods. One of the advantages of the new unified gas transport model is its great flexibility which is capable to cover the full flow regimes. It is found that the increase of real gas viscosity can reduce the total molar flux in the inorganic pores up to 66.0%. In addition, it is observed that the pore confinement effect is of importance when the pore size is smaller than 50 nm. The apparent permeability is found to increase greatly as the adsorption layer number increases, implying that the application of Langmuir model in existing gas transport models may substantially underestimate it. Given organic nanopores, the contribution of surface diffusion is tangible when the pore size is below 150 nm and the Knudsen diffusion is negligible under high pressures. Compared with the flow mechanisms in the nanopores, it is found that the fractal dimension of the tortuosity has the largest impact on the production rate than the pore size and the fractal dimension of pore size distribution. In addition, the fuzzy statistical method can quantify the confidence interval within which the satisfactory flow rate results can be acquired. The fuzzy statistical method enables more flexibility to predict the realistic production profile with significant data fluctuations

Kinetic Compensation Effect in Logistic Distributed Activation Energy Model for Lignocellulosic Biomass Pyrolysis

The kinetic compensation effect in the logistic distributed activation energy model (DAEM) for lignocellulosic biomass pyrolysis was investigated. The sum of square error (SSE) surface tool was used to analyze two theoretically simulated logistic DAEM processes for cellulose and xylan pyrolysis. The logistic DAEM coupled with the pattern search method for parameter estimation was used to analyze the experimental data of cellulose pyrolysis. The results showed that many parameter sets of the logistic DAEM could fit the data at different heating rates very well for both simulated and experimental processes, and a perfect linear relationship between the logarithm of the frequency factor and the mean value of the activation energy distribution was found. The parameters of the logistic DAEM can be estimated by coupling the optimization method and isoconversional kinetic methods. The results would be helpful for chemical kinetic analysis using DAEM

Prevalence of internet addiction disorder in Chinese university students: A comprehensive meta-analysis of observational studies

Background and aims: Internet addiction disorder (IAD) is common in university students. A number of studies have examined the prevalence of IAD in Chinese university students, but the results have been inconsistent. This is a meta-analysis of the prevalence of IAD and its associated factors in Chinese university students. Methods: Both English (PubMed, PsycINFO, and Embase) and Chinese (Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from their inception until January 16, 2017. Results: Altogether 70 studies covering 122,454 university students were included in the meta-analysis. Using the random-effects model, the pooled overall prevalence of IAD was 11.3% (95% CI: 10.1%–12.5%). When using the 8-item Young Diagnostic Questionnaire, the 10-item modified Young Diagnostic Questionnaire, the 20-item Internet Addiction Test, and the 26-item Chen Internet Addiction Scale, the pooled prevalence of IAD was 8.4% (95% CI: 6.7%–10.4%), 9.3% (95% CI: 7.6%–11.4%), 11.2% (95% CI: 8.8%–14.3%), and 14.0% (95% CI: 10.6%–18.4%), respectively. Subgroup analyses revealed that the pooled prevalence of IAD was significantly associated with the measurement instrument (Q = 9.41, p = .024). Male gender, higher grade, and urban abode were also significantly associated with IAD. The prevalence of IAD was also higher in eastern and central of China than in its northern and western regions (10.7% vs. 8.1%, Q = 4.90, p = .027). Conclusions: IAD is common among Chinese university students. Appropriate strategies for the prevention and treatment of IAD in this population need greater attention

Metagenomic Characterization and Volatile Compounds Determination in Rumen from Saanen Goat Kids Fed Olive Leaves

Simple Summary The aim of this study was to characterize the rumen microbiota of Saanen goat kids fed olive leaves through a high-throughput approach based on 16S rRNA gene sequencing; furthermore, the parallel characterization of rumen volatile profile by solid-phase microextraction coupled with gas chromatography-mass spectrometry has been performed. Twenty goat kids were randomly assigned to two groups. The first group received a basal diet, while in the second one the diet was supplemented with olive leaves. The results showed the dietary supplementation to be able to affect the microbial community in the rumen. Significant differences were specifically observed between the two groups at genera and even family levels characterized by a higher abundance of cellulolytic bacteria in the rumen of goat kids fed olive leaves. In addition, the analysis of volatile compounds at the rumen level has allowed us to highlight differences in relation to the diet and the presence, in the rumen of goat kids fed olive leaves, of compounds indicative of health status. The accumulation and disposal of by-products deriving from the agro-food industry represents a problem both from an economic and environmental point of view. The use of these matrices in zootechnical nutrition could represent a feasible solution. The aim of the study was to examine the effect of a diet containing olive leaves (OL), a by-product of the olive industry, on the ruminal microbial community of Saanen goat kids and on volatile organic compounds (VOCs) produced during the digestion. Twenty goat kids were randomly divided into two groups of ten goat kids each. The control group (CTR) was fed with a standard diet, while the experimental group (OL+) received a custom-formulated diet containing 10 % OL on a dry matter (DM) basis. After 30 days of trial, genomic DNA was extracted from the rumen liquor and prepared for 16S rRNA-gene sequencing to characterize the rumen microbiota; furthermore, rumen VOCs were also characterized by solid-phase microextraction coupled with gas chromatography-mass spectrometry. The Shannon's alpha index was not significantly different between the two groups, on the contrary, Bray-Curtis (p < 0.01) and Jaccard (p < 0.01) distances evidenced that feed affected microbial community. Eleven genera were influenced by OL supplementation, with a significant increase (p < 0.05) in Paludibacter, Fibrobacter, Sphaerochaeta Christensenella, Rikenella, Oligosphaera, Candidatus Endomicrobium, Anaerovorax, and Atopobium was observed, while the percentages of Bacteroides and Selenomonas were reduced (p < 0.05). Differences were also observed between the two groups at the family level (p < 0.004). Fibrobacteriaceae, Christensenellaceae, Coriobacteriaceae, Oligosphaeraceae, Candidatus Endomicrobium, and Planctomycetaceae were significantly higher (p < 0.05) in goat kids fed OL diet compared to CTR, while the levels of other identified families, Succinivibrionaceae and Bifidobacteriaceae, were opposite (p < 0.05). Finally, results showed that the main phyla in both groups were Bacteroidetes and Firmicutes; however, no significant differences in the relative abundance of any phyla were observed between the two groups. In addition to what has been reported, the analysis of VOCs at the rumen level showed the ability of the OL integration to induce an increase in hexanoic acid and a parallel decrease in decanal. Furthermore, only in OL+ samples there was the accumulation of alpha-terpineol to which a wide range of interesting biological properties is attributed.The presence of VOCs associated with health status suggests a favorable role of OL in preserving and improving animal welfare

A scoping review of burden of disease studies estimating disability-adjusted life years due to Taenia solium

Background Taenia solium is the most significant global foodborne parasite and the leading cause of preventable human epilepsy in low and middle-income countries in the form of neurocysticercosis. Objectives This scoping review aimed to examine the methodology of peer-reviewed studies that estimate the burden of T. solium using disability-adjusted life years. Eligibility criteria Studies must have calculated disability-adjusted life years relating to T. solium. Charting methods The review process was managed by a single reviewer using Rayyan. Published data relating to disease models, data sources, disability-adjusted life years, sensitivity, uncertainty, missing data, and key limitations were collected. Results 15 studies were included for review, with seven global and eight national or sub-national estimates. Studies primarily employed attributional disease models that relied on measuring the occurrence of epilepsy before applying an attributable fraction to estimate the occurrence of neurocysticercosis-associated epilepsy. This method relies heavily on the extrapolation of observational studies across populations and time periods; however, it is currently required due to the difficulties in diagnosing neurocysticercosis. Studies discussed that a lack of data was a key limitation and their results likely underestimate the true burden of T. solium. Methods to calculate disability-adjusted life years varied across studies with differences in approaches to time discounting, age weighting, years of life lost, and years of life lived with disability. Such differences limit the ability to compare estimates between studies. Conclusions This review illustrates the complexities associated with T. solium burden of disease studies and highlights the potential need for a burden of disease reporting framework. The burden of T. solium is likely underestimated due to the challenges in diagnosing neurocysticercosis and a lack of available data. Advancement in diagnostics, further observational studies, and new approaches to parameterising disease models are required if estimates are to improve

Effect of acupuncture and auricular acupressure on smoking cessation:Protocol of a systematic review and Bayesian network meta-analysis

BACKGROUND: Tobacco epidemic remains a major challenge to public health, with >7 million deaths attributable to tobacco smoking p.a. Quitting smoking is a proven way of reducing the harm of smoking. Nicotine replacement therapy (NRT), auricular acupressure and acupuncture are used for quit smoking, but it remains to be explored which is relatively more effective. Furthermore, a Bayesian network meta-analysis will be applied to determine the relative effects and/or safety of different smoking cessation treatments. METHODS/DESIGN: A literature search for randomized controlled trials (RCTs) will be performed in five electronic databases from inception to December 2019, including PubMed, the Cochrane library, EMBASE, Web of Science, and Chinese Biomedical Database (SinoMed). Cochrane Collaboration quality assessment tool will be used for the risk of bias assessment. A Bayesian network meta-analysis will be performed using WinBUGS 1.4.3, and Stata 14 will be applied to draw the network diagram, while RevMan 5.3.5 will be used to produce funnel plot for assessing the risk of publication bias. Recommended rating, development and grade methodology will also be utilized to assess the quality of evidence. RESULTS: We will evaluate the effect of different smoking cessation treatments (e.g., acupuncture, auricular acupressure, and NRT) by directly traditional meta-analysis and indirectly Bayesian network meta-analysis. CONCLUSION: Our study will provide smokers with the available evidence on the efficacy and safety of quitting regimens