In order to analyze and compare the differences in pore structures between shale gas and shale oil formations, a few samples from the Longmaxi and Bakken Formations were collected and studied using X-ray diffraction, LECO TOC measurement, gas adsorption and field-emission scanning electron microscope. The results show that samples from the Bakken Formation have a higher TOC than those from the Longmaxi Formation. The Longmaxi Formation has higher micropore volume and larger micropore surface area and exhibited a smaller average distribution of microsize pores compared to the Bakken Formation. Both formations have similar meso-macropore volume. The Longmaxi Formation has a much larger meso-macropore surface area, which is corresponding to a smaller average meso-macropore size. CO2 adsorption data processing shows that the pore size of the majority of the micropores in the samples from the Longmaxi Formation is less than 1 nm, while the pore size of the most of the micropores in the samples from the Bakken Formation is larger than 1 nm. Both formations have the same number of pore clusters in the 2–20 nm range, but the Bakken Formation has two additional pore size groups with mean pore size diameters larger than 20 nm. Multifractal analysis of pore size distribution curves that was derived from gas adsorption indicates that the samples from the Longmaxi Formation have more significant micropore heterogeneity and less meso-macropore heterogeneity. Abundant micropores as well as meso-macropores exist in the organic matter in the Longmaxi Formation, while the organic matter of the Bakken Formation hosts mainly micropores.
In this paper, two new nanoscale-extended attractive (alpha) functions in Soave and exponential types are developed for the first time, which are applied and evaluated for the calculations of the thermodynamic and phase properties of confined fluids coupled with a modified equation of state (EOS). Moreover, a novel method is proposed and verified to determine the nanoscale acentric factors. The behaviour of several important parameters, i.e., minimum reduced temperature, nanoscale acentric factor, alpha function and its first and second derivatives, are specifically analyzed at different temperatures and pore radii. The newly-developed alpha functions are validated to accurately calculate the thermodynamic and phase properties in bulk phase (rp = 1000 nm) and nanopores. The minimum reduced temperature from the Soave alpha function occurs at the acentric factor of ω = −0.295211 while the exponential function is monotonically related to the temperatures without any minimum conditions. Moreover, the acentric factors and intermolecular attractivities are found to be increased with the pore radius reductions at most temperatures, wherein they remain constant or slightly increase by reducing the pore radius at rp ≥ 50 nm while become quickly increased at rp < 50 nm. It should be noted that the alpha functions are decreased with the pore radius reduction at the critical temperature (Tr = 1). The intermolecular attractivities are found to be stronger for the heavier or high carbon number components. Furthermore, the first and second derivatives of the Soave and exponential alpha functions to the temperatures are continuous at T ≤ 4000 K. Overall, the two original (Soave and exponential) and two nanoscale-extended alpha functions are proven to be accurate for the thermodynamic and phase calculations in bulk phase and nanopores.
Evidence suggesting an association between ozone exposure and stroke risk remains inconsistent; variations in the distributions of susceptibilities of the study populations may explain some of it. We examined the hypothesis in a general Chinese population. During 2013–2015, 1356 first-ever stroke events were selected from a large representative sample, the China National Stroke Screening Survey (CNSSS) database; daily maximal 8-hour ozone concentrations were obtained from spatiotemporally interpolated estimates of in-situ observations over China. We conducted a time-stratified case-crossover design to assess associations between stroke risk and ambient ozone exposure. Next, potential effect modifiers were identified using interaction analyses. Final, a well-established approach was applied to estimate individual-level susceptibility (i.e., the individual-specific effect given a certain combination of multiple effect-modifiers) and its probability distribution among all the CNSSS participants (n = 1,292,010). With adjustments for temperature, relative humidity and ambient fine particulate matter exposure, a 10-μg/m3 increment in mean ozone levels 2–3 day prior to symptom onset was associated with a 3.0% change in stroke risk (95% confidence interval: −1.2%, 7.3%). This association was statistically significantly enhanced by male gender, rural residence and low vegetable and fruit consumption. The subgroup results suggested that a fraction of the population might be considerably affected by ozone, regardless of the insignificant association in average level. The analysis of susceptibility distribution further indicated that the ozone-stroke association was statistically significantly positive in 14% of the general population. Susceptibility to ozone-related stroke significantly varied among Chinese adults. Characterizing individual-level susceptibility reveals the complexity underlying the weak average effect of ozone, and supports to plan subpopulation-specific interventions to mitigate the stroke risk.
Mutations in hepatitis B virus (HBV) surface promoter II (SPII) have not been well studied in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients. We aimed to investigate SPII mutations in such patients and their biological and clinical impacts. Direct sequencing was used to detect SPII mutations in 106 HBeAg-positive treatment-naïve CHB patients with genotype C (82.1% (87/106) was C2) HBV infection. Results showed that mutation frequency in transcription factor (TF) unbinding region was significantly higher than that in TF binding region of SPII (C1: 3.4% vs. 1.3%; C2: 2.6% vs. 1.3%; p < 0.0001). Luciferase assay revealed distinct promoter activities among SPII mutants; especially SPII of G120A mutant had a 15-fold higher activity than that of wild-type (p < 0.001). In vitro experiments in HepG2 cells showed that G82A, A115C and G120A mutants increased the hepatitis B surface antigen (HBsAg) levels, while C18T had an opposite effect. G82A, A115C and G120A mutants boosted the intracellular HBV total RNA level. G120A mutation resulted in an increased HBV DNA level in vitro, consistent with the serological results in patients. Thus, novel SPII mutations would affect promoter activity, HBsAg, HBV DNA and HBV total RNA levels, suggesting their potential biological and clinical significances.
Keywords: C genotype; HBeAg-positive; HBsAg; hepatitis B virus; mutation; surface promoter.
With the development of droplet microfluidic technology, there are some problems in the current generation of droplets using microchannels, such as high cost, and difficulty in controlling the size of droplets and the generation frequency. This paper applies numerical simulation method to study T-junction microchannels. Studies have shown that the pressure difference in the T-junction microchannel and the viscous shear force of the continuous phase act as a driving force in the droplet formation process. The effective droplet diameter decreases as the Ca increases, and the generation frequency increases as Ca increases. Based on the level-set method, three T-junction microchannels with step structure at different positions are designed to study the problem of generating monodisperse high-throughput microdroplets. This paper achieves flexible control of droplet generation using three different designs. In the three designs, when the step position is in the middle, the generated droplet diameter is the smallest and the frequency is the fastest. Therefore, studies have shown that the step structure in the middle is the optimal solution for generating monodisperse high-throughput microdroplets.
In this paper, a three-dimensional numerical simulation of the merged droplet formation (MDF) in the double T-junction microchannel was performed to investigate the effects of the flow rate of the continuous phase, continuous viscosity and the interfacial tension on the pressure by the level-set method. We divide the droplet formation process into three stages, namely filling, blocking and breakup. We define the time to generate a droplet as the droplet generation period. The characteristic length L/W (L is the length of the droplet, and W is the width of the main channel) decreases as the capillary number increases. The pressure (P-A) at a special position at the junction of the two phases occurs periodically during the droplet formation process, which directly and precisely reflects the mechanism of the MDF in the microchannel. Therefore, we define the time during the pressure fluctuates periodically as the pressure fluctuation period. New insights into the pressure during the MDF in the squeezing time are reported. The results show that the pressure fluctuation period and pressure drop period are the same as the droplet generation period. When the continuous flow rate and viscosity increase, the peak and valley values of P-A and the pressure drop increase, and the time of the pressure cycle decreases. However, when the interfacial tension increases, the peak and theperiod increase and the valley decreases. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
This paper investigates whether household beliefs on the determinants of success affect their stock market participation decisions. Using national survey data from China, I show that Chinese households believe that personal effort is the most influential factor in people’s success, followed by family social connections, aptitude, and luck. Moreover, households that believe more in effort are less likely to participate in the stock market, while those who place more emphasis on family social connections are more likely to participate. The negative (positive) effects of effort (family social connections) are more profound for agricultural (workplace-affiliated) households. Further, I offer belief mechanisms to explain the heterogeneity of stock market participation for different occupations.
Since the concentration of target molecules contained in most reagents in analytical chemistry experiments is lower than the minimum concentration required for subsequent detection, it is necessary for sample enrichment. Electrokinetic trapping that utilizes the principle of ion concentration polarization to achieve biomacromolecular enrichment is the most efficient. In this paper, based on the Poisson-Nernst-Plank equation, a novel design of nanochannel structure in a micro-nanofluidic preconcentrator for electrokinetic ion enrichment is carried out by numerical simulation. The results show that the enrichment process can be divided into three stages: enrichment generation, enrichment promotion and enrichment breakdown when the applied voltage is increased. Importantly, by comparing the six different structure nanochannels (straight line type, square wave type, rectangular type, circle type, zigzag type and multi-wave type), we found that the enrichment ratio produced by the rectangular nanochannel is the highest of the six nanochannels, which is 20.7 times. Rectangular nanochannel requires the lowest applied voltage to achieve the highest enrichment ratio. This work provides a novel design method and theoretical basis for the design of detection equipment in ultra-low concentration molecular detection tasks.
D-amino acid (DAA) an environmentally friendly biofilm inhibitor, has low efficiency for membrane biofouling control due to its instability. To address this challenge, a novel nanocomposite was prepared with DAA adhering to polydopamine (PDA)-coated halloysite nanotube (HNTs) through the interactions of H-bonding and π-π stacking between PDA and DAA. Membrane modified with such nanocomposite was fabricated via blending phase inversion, and the nanocomposite was uniformly distributed in the modified membrane matrix. In comparison with the pristine membrane, the addition of nanocomposites resulted in robust mechanical property for modified membrane with the ultimate stress and strain increased by 23.97% and 35.62%, respectively. Moreover, an excellent tradeoff between water flux (2.5 folds of pristine membrane) and selectivity was achieved, probably due to the improved membrane hydrophilicity. Meanwhile, bovine serum protein (BSA) static adsorption as well as dynamic filtration experiments exhibited excellent antifouling ability of the modified membrane. Most importantly, a superior anti-biofouling stability over a 10-day period was obtained for the membrane modified with nanocomposite, indicating that the activity of DAA to mitigate biofouling was effectively maintained. This study developed a novel and promising strategy for membrane biofouling mitigation.
Unbounded potentials are always utilized to strictly confine quantum dynamics and generate bound or stationary states due to the existence of quantum tunneling. However, the existed accurate Wigner solvers are often designed for either localized potentials or those of the polynomial type. This paper attempts to solve the time-dependent Wigner equation in the presence of a general class of unbounded potentials by exploiting two equivalent forms of the pseudo-differential operator: integral form and series form (i.e., the Moyal expansion). The unbounded parts at infinities are approximated or modeled by polynomials and then a remaining localized potential dominates the central area. The fact that the Moyal expansion reduces to a finite series for polynomial potentials is fully utilized. In order to accurately resolve both the pseudo-differential operator and the linear differential operator, a spectral collocation scheme for the phase space and an explicit fourth-order Runge-Kutta time discretization are adopted. We are able to prove that the resulting full discrete spectral scheme conserves both mass and energy. Several typical quantum systems are simulated with a high accuracy and reliable estimation of macroscopically measurable quantities is thus obtained.
The coastal area of the East China Sea has experienced rapid urbanization and industrialization in China since 1980s, resulting in severe pollution of its environments. Antibiotic resistance genes (ARGs) are regarded as a kind of emerging pollutant with potential high risk. The sediment samples were collected from Hangzhou Bay (HB), Xiangshan Bay (XB), and Taizhou Bay (TB) to investigate the spatial occurrence and distribution of 27 ARGs and class I integron–integrase gene (intI1) in the coastal area of the East China Sea. The PCR results showed the frequent presence of 11 ARGs and intI1 in the sediments of the three bays. The qPCR results further showed that sulfonamide resistance was the most prevalent ARG type and antibiotic target replacement and protection were the most important resistance mechanisms in the sediments. Regarding the subtype of ARGs, sulI, tetW, and dfrA13 were the most abundant ARGs, in which sulI was higher in TB (based on both the absolute and relative abundances) and dfrA13 was higher in HB (based on the relative abundances). The network analysis revealed that intI1 had significant correlations with tetC, sulI, sulII, and blaPSE-1. Oil was the key connected factor, which had positive connections with sulI, sulII, and blaPSE-1. In addition, the joint effect of heavy metals and nutrients & organic pollutants might be crucial for the fate of ARGs in the coastal sediments.