Styrene made from raw pyrolysis gasoline contains sulfur impurities such as 2-vinyl thiophene. We prepared three sorbents, namely, AgY, AgNO3/γ-Al2O3, and AgNO3/SiO2, to remove 2-vinyl thiophene from styrene. All three sorbents showed good desulfurization performance while AgY had the highest sulfur capacity. This was due to π-complexation, where the silver cations in AgY can bond 2-vinyl thiophene more strongly than styrene. The desulfurization capacity of AgNO3/γ-Al2O3 was better than that of AgNO3/SiO2 when taking its lower silver loading and surface area into consideration. Moreover, prewetting the sorbents was critical for desulfurization but can cause polymerization. Comparison between desulfurization of gasoline and styrene, using AgY, shows its superior sulfur adsorption capacity for desulfurization of styrene. A possible mechanism on the preferential adsorption for 2-vinyl thiophene over styrene by Ag+ is given via the comparison between thiophene and benzene.
AIM: To assess the effects of Hydroxymethylglutaryl coenzyme A reductase inhibitor simvastatin (Sim) on cardiac function, cardiomyosin heavy chain(MHC) and actin expression in rats with myocardial infarction. METHODS: The myocardial infarction (MI) models were induced by ligation of anterior descending coronary artery in Wistar rats. Twenty-four hours later, the survivals were randomly divided into 3 groups: MI group, 20 mg Sim group and 40 mg Sim group, the rats with sham ligation formed into sham group. The rats in the two Sim groups received intragastric administration of Sim 20 and 40 mg/kg·d. Respectively for 8 weeks. The rats in MI group and sham group were treated with the same quantity of solvent as placebo. After 8 weeks, the hemodynamic parameters were examined. The α- and β- MHC mRNA expressions in non-infarcted zone were detected by RT-PCR. The skelecton α-actin (Sk α-actin) expression was detected by immunohistochemistry. RESULTS: Compared with sham group, in MI group, left ventricular end-diastolic pressure (LVEDP) was increased and left ventricular systolic pressure (LVSP) was depressed significantly. Compared with MI group, LVEDP was depressed and LVSP was increased in the two Sim groups. The α-MHC mRNA expression was lower and the β- MHC mRNA expression was higher in MI group than in Sham group. Compared with MI group, the α- MHC mRNA expression was enhanced and the β- MHC mRNA expression was lessened in both Sim groups. The expression of Sk α-actin was weak in sham group and strong in MI group, and the expression decreased in both Sim groups. CONCLUSION: Simvastatin attenuates the mRNA expression of α-MHC and enhances β-MHC mRNA expression. It also decreases the Sk α-actin expression in rats after MI. It may play some roles in the restraint of cardiac hypertrophy and the improvement of myocardial remodeling.
Abstract After polymer flooding, a low-resistant dominant seepage channel forms at the bottom of the high-permeability reservoir, which is extremely disadvantageous for further enhanced oil recovery. In this study, we proposed a new method to plug the dominant seepage channel after polymer flooding, through fracturing–seepage–plugging using a solid-free plugging agent, which can achieve deeper and further regional plugging. This method involved dissolving the crosslinking agent and stabilizer in the water-based fracturing fluid (hereinafter referred to as the fracturing plugging agent) and transporting it to the target reservoir through hydraulic fractures. The fracturing plugging agent percolated into the deep part of the reservoir under the action of fracture closure pressure and gelled with the residual polymer in the formation to achieve deep regional plugging of the advantageous channel. To study the percolation law of fracturing plugging agent in the dominant channel, high-pressure displacement experiments were conducted using natural cores under different permeability and concentration conditions of the fracturing plugging agent. The results showed that the percolation rate of the fracturing plugging agent was almost linearly related to reservoir permeability. Due to the formation of micro-fractures and crosslinking reactions, the percolation rate first increased and then decreased to a stable state. After a certain period, the pores were blocked, resulting in a sharp decrease in the percolation rate and then decayed. In addition, the higher the concentration of fracturing plugging agent, the better the core plugging performance. Moreover, when the concentration of fracturing plugging agent injected into the core exceeded 3,000 mg/L, the core permeability increased, and the breakthrough pressure evidently increased three to four times. On the basis of this, rheometer tests, scanning electron microscopy (SEM) observations, and mercury intrusion tests were performed to evaluate gelation performance, shear effect, and pore retention morphology of the crosslinking system made by mixing the injected plugging agent and residual polymer in the reservoir. The results showed that the shear action could reduce the gelling property, and the concentration of fracturing plugging agent should be >3,000 mg/L to meet the requirements of gelling. Furthermore, the viscosity of the crosslinking system reached the peak value at approximately 72 h, forming a network space structure of layered superposition, thereby increasing viscosity by 40–50 times. Finally, SEM images revealed that after the fracture plugging agent was injected into the core, the micelles were mostly concentrated in the front and middle sections. The average pore radius of the core decreased by 8.620 μm, and the average porosity decreased by 54.85%.
Recent development in applications of new biomaterials and biomedical engineering enable the tissue engineering to become a promising cartilage repair technique. Here, a 3-D alginate scaffold was fabricated by a cross-linked method. Experiments were performed to investigate how the porosity and permeability of the 3-D scaffold, as well as the proliferation rate of seeded cells, were affected by the ultrasound exposure parameters. The scanning electron microscopy and fluorescence imaging were used to examine the micro-structure, porosity, and permeability of the scaffolds, and biochemical analyses were applied to assess the cell growth in the scaffold. The optimum low intensity pulsed ultrasound (LIPU) driving parameters that benefit the enhancement of scaffold porosity and cell proliferation were also explored. The results suggest that, for the scaffold exposed to LIPU, its porosity and permeability could be significantly enhanced by the increasing LIPU amplitude, which might be induced by the microstreaming shear stress generated by ultrasound-driven microbubble oscillations. The assessments of cell proliferation and collagen II expression confirmed that, with appropriately selected LIPUS driving parameters, chondrocytes growth could be effectively promoted in 3-D alginate scaffolds treated by LIPU, because of the improved scaffold porosity and permeability might benefit cell growth space and nutrition supply.
A simple, low-cost method was applied to prepare hybrid photocatalysts of copper (I) oxide/titania. Five different TiO₂ powders were used to perform the study of the effect of titania matrix on the photocatalytic and antimicrobial properties of prepared nanocomposites. The photocatalytic efficiency of such a dual heterojunction system was tested in three reaction systems: ultraviolet-visible (UV-Vis)-induced methanol dehydrogenation and oxidation of acetic acid, and 2-propanol oxidation under visible light irradiation. In all the reaction systems considered, the crucial enhancement of photocatalytic activity in relation to corresponding bare titania was observed. The reaction mechanism for a specific reaction and the influence of titania matrix were discussed. Furthermore, antimicrobial (bactericidal and fungicidal) properties of Cu₂O/TiO₂ materials were analyzed. The antimicrobial activity was found under UV, visible and solar irradiation, and even for dark conditions. The origin of antimicrobial properties with emphasis on the role of titania matrix was also discussed.
Although hydrogel-based electronic devices have received a lot of interest for good flexibility, biocompatibility, and multifunctionality over the past decades, underwater instability (especially in saline solutions) still limits their practical applications to a wide range. Herein, a class of tough, conductive, and anti-swelling double-network hydrogel is developed by combining the zwitterionic poly(acrylamide-co-(3-(1-(4-vinylbenzyl)-1H-benzo[d]imidazole-3-ium-3-yl) propane-1-sulfonate)) chemical network and water-resistant polyvinyl alcohol physical network with conducting polypyrrole. The resultant gel exhibits considerable mechanical strength (0.65 MPa), stable swelling dynamics in water and seawater, as well as excellent ionic conductivity (3.96 S/m). Furthermore, the assembled gel-based sensor shows distinct strain/temperature bi-modal detection. Moreover, by controlling the dimension of conductive networks, an all-in-one supercapacitor can be obtained, with ultra-high capacitance (299.79 mF/cm2) and power density (2.49 mW/cm2). We believe that this strategy will inspire researchers to develop more reliable underwater, self-powered multi-modal sensing devices in the future.
A Ni/PyBisulidine catalyzed asymmetric Michael addition of 3-acyloxy-2-oxindoles to nitroalkenes has been developed. Various quaternary substituted 3-acyloxy-2-oxindoles were obtained with excellent yields and diastereo- and enantioselectivities in a low-toxic green solvent, ethyl acetate, with a low catalyst loading (1 mol%). The reaction process is air and moisture tolerant. The substrate scope was also extended to α,β-disubstituted nitroalkenes and 3-hydroxy-2-oxindoles, and good results were obtained.
Understanding the mechanical properties and energy response of high‐porosity concrete under the cyclic loading and unloading is the foundation of road construction in sponge city. In this study, the concrete with the porosity of 15% was taken as the research object, and the cyclic loading and unloading tests on the high‐porosity concrete were performed under the stress amplitude of 25 MPa, 30 MPa, and 35 MPa in the elastic stage. The effects of stress amplitude and cycle number on the mechanical characteristics and damage evolution law of concrete were obtained. The experimental results show the following. (1) With the increase of cycle number, the loading and unloading elastic modulus of concrete under different stress amplitudes first increases and then decreases; the greater the stress amplitude, the faster the growth and deceleration of the loading and unloading elastic modulus. (2) With the increase of the cycle number, the peak strain and residual plastic deformation increase. (3) The greater the stress amplitude, the higher the damage of concrete; with the increasing number of cyclic loading and unloading, the damage of concrete is enhanced gradually. When the damage variable value is 1, the relationship between the cycle number and the initial stress amplitude satisfies a negative exponential function.
Solar-driven water splitting powered by photovoltaics enables efficient storage of solar energy in the form of hydrogen fuel. In this work, we demonstrate efficient solar-to-hydrogen conversion using perovskite (PVK) tandem photovoltaics and a halogen-modulated metal-organic framework (MOF) electrocatalyst. By substituting tetrafluoroterephthalate (TFBDC) for terephthalic (BDC) ligands in a nickel-based MOF, we achieve a 152 mV improvement in oxygen evolution reaction (OER) overpotential at 10 mA·cm2. Through X-ray photoelectron spectroscopy (XPS), X-ray adsorption structure (XAS) analysis, theoretical simulation, and electrochemical results, we demonstrated that the introduction of fluorine atoms enhanced the intrinsic activity of Ni sites as well as the transfer property and accessibility of the MOF. Using this electrocatalyst in a bias-free photovoltaic electrochemical (PV-EC) system with a PVK/organic tandem solar cell, we achieve 6.75% solar-to-hydrogen efficiency (ηSTH). We also paired the electrocatalyst with a PVK photovoltaic module to drive water splitting at 206.7 mA with ηSTH of 10.17%.
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