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By maintaining a high shear rate, dynamic filtration (DF) provides excellent performances in controlling fouling and improving flux during filtration. Many DF devices comprising a mechanical movement generated by the rotation, osc...
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By maintaining a high shear rate, dynamic filtration (DF) provides excellent performances in controlling fouling and improving flux during filtration. Many DF devices comprising a mechanical movement generated by the rotation, oscillation and/or vibration of one element have been developed. Based on the bibliometric analysis, new applications and technologies related to DF have become the new research hotspots. Major applications were reported in food processing, water treatment and bioprocess engineering. With a precise definition of the concepts of oscillation and vibration, 55 DF modules have been classified into 15 different types according to movement and shape (filtration cell, membrane, impeller, disk...). But it appears that it remains a great challenge to complete the knowledge on the flow of fluid inside DF modules because of their complex geometries. Global, semi-local and local investigation of hydrodynamics have been detailed. They not only make it possible to estimate performances but also to help to calculate energy consumption according to operating conditions. This review presents the main characteristics of DF devices and existing applications. These empirical results are already beneficial for the selection of DF devices for a dedicated application. However, a better understanding of local and temporal variations in pressure and shear stress is still necessary to refine the choice of a device and the operating conditions. The overarching aims propose to report the main criteria that will help engineers select the DF module or identify the scientific and/or technological bottlenecks about hydrodynamics or applications.
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In this paper, a full hydrodynamic semiconductor model with a time periodic external force is concerned. First, we regularize the system under consideration and prove the existence of time periodic solutions to the linearized appr...
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In this paper, a full hydrodynamic semiconductor model with a time periodic external force is concerned. First, we regularize the system under consideration and prove the existence of time periodic solutions to the linearized approximate system by applying Tychonoff fixed point theorem combined with the energy method and the decay estimates. This idea is from the Massera-type criteria for linear periodic evolution equations. Then, the existence of a strong time periodic solution under some smallness assumptions is established by using the topological degree theory and an approximation scheme. The uniqueness of time periodic solutions is proved basing on the energy estimates. Also, the existence of the stationary solution is obtained.
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Mxra8 is a receptor for multiple arthritogenic alphaviruses that cause debilitating acct and chronic musculoskeletal disease in humans. Herein, we present a 2.2 angstrom resolution X-ray crystal structure of Mxra8 and 4 to 5 angst...
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Mxra8 is a receptor for multiple arthritogenic alphaviruses that cause debilitating acct and chronic musculoskeletal disease in humans. Herein, we present a 2.2 angstrom resolution X-ray crystal structure of Mxra8 and 4 to 5 angstrom resolution cryo-electron microscopy reconstructions of Mxra8 bound to chikungunya (CHIKV) virus-like particles and infectious virus. The Mxra8 ectodomain contains two strand-swapped Ig-like domains oriented in a unique disulfide-linked head-to-head arrangement. Mxra8 binds by wedging into a cleft created by two adjacent CHIKV E2-E1 heterodimers in one trimeric spike and engaging a neighboring spike. Two binding modes are observed with the fully mature VLP, with one Mxra8 binding with unique contacts. Only the high-affinity binding mode was observed in the complex with infectious CHIKV, as viral maturation and E3 occupancy appear to influence receptor binding-site usage. Our studies provide insight into how Mxra8 binds CHIKV and creates a path for developing alphavirus entry inhibitors.
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In this paper, we address a single-lot, lot streaming problem for a two-stage hybrid flow shop, which consists of one machine at Stage 1 and two parallel (identical) machines at Stage 2. The objective is to minimize makespan. The ...
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In this paper, we address a single-lot, lot streaming problem for a two-stage hybrid flow shop, which consists of one machine at Stage 1 and two parallel (identical) machines at Stage 2. The objective is to minimize makespan. The lot is to be split into sublots each of which is processed first on the machine at Stage 1, and then, on one of the machines at Stage 2. A sublot-attached removal time is incurred after processing each sublot at Stage 1. First, we assume the number of sublots for the lot to be known a priori and develop closed-form expressions to obtain optimal, continuous sublot sizes for this case. Then, we consider determination of an optimal number of sublots in addition to their sizes. We develop an upper bound on the number of sublots, , and use an algorithm of complexity in conjunction with the closed-form expressions for sublot sizes to obtain an optimal solution. We also address the problem of determining number of sublots and integer sublot sizes, and propose a heuristic method for its solution that relies on some key results from the continuous case of the problem. The results of our numerical experimentation reveal the efficacy of the proposed method to obtain near-optimal integer sublot sizes and makespan values that are within 2.35 % of the true optimum for the testbed of data used, each obtained within a few seconds of CPU time.
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Ammonia (NH3) and nitrates are essential for human society because of their widespread utilization for producing medicines, fibers, fertilizers, etc. In recent years, the development on nitrogen fixation under mild reaction condit...
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Ammonia (NH3) and nitrates are essential for human society because of their widespread utilization for producing medicines, fibers, fertilizers, etc. In recent years, the development on nitrogen fixation under mild reaction conditions has attracted much attention. However, the very low conversion efficiency and ambiguous catalytic mechanism remain the major hurdles for the research of nitrogen fixation. This review aims to clarify the role of chemical bond in catalytic nitrogen fixation by summarizing and analyzing the recent development of nitrogen fixation research. In detail, the atomic-scale mechanism of nitrogen fixation reaction, the various methods to improve the nitrogen fixation performance, and the computational investigation of nitrogen fixation are discussed, all from a chemical bond perspective. It is hoped that this review could trigger more profound pondering and deeper exploration in the field of catalytic nitrogen fixation.
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Shale oil and gas have been discovered in the lacustrine organic-rich Zhangjiatan Shale of the Upper Triassic Yanchang Formation, Ordos Basin, China. Core observations indicate abundant silty laminae in the producing shales. This ...
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Shale oil and gas have been discovered in the lacustrine organic-rich Zhangjiatan Shale of the Upper Triassic Yanchang Formation, Ordos Basin, China. Core observations indicate abundant silty laminae in the producing shales. This study documents the stratigraphic distribution of silty laminae and their relationship with interlaminated clay laminae. The type, structure, and characteristics of pores and mineral composition of silty laminae were observed and analyzed through thin section and scanning electron microscopy, X-ray diffraction, low-pressure CO2 and N-2 adsorption, mercury porosimetry, and helium pycnometry. Results from silty laminae are compared with those of clayey laminae. The frequency and thickness of silty laminae vary over a wide range. The thickness ranges from 0.2 to 4 mm and is 1.5 mm on average; the frequency ranges from 4 to 32 laminae/m and is 23 laminae/m on average. The thickness percentage of silty laminae in the measured segments ranges from 6% to 17%. Silty laminae consist of quartz, feldspar, mixed-layer montmorillonite, and chlorite. In comparison to clayey laminae, non-clay detrital grains are larger, quartz and feldspar are more common, and clay minerals are less abundant. Pores in silty laminae are primary interparticle, dissolutional, intercrystalline, and microfracture types. Mesopores (2-50 nm in diameter) and macropores (50 nm-1 um) are common, whereas, micropores (<2 nm) are rare; the distribution of pore diameters is multimodal. However, microscopic pores with a diameter commonly smaller than 100 nm are common in clayey laminae. Thus, pore volume and surface area of micropores in silty laminae are less than those in the adjacent clayey laminae, and vice versa for meso- and macropores. The porosity of shales increases with the proportion of silty laminae in the shales. The silty laminae provide the storage space and flow conduit for oil and gas, and they play a significant role in the migration, accumulation, occurrence, and amount of gas in the shales.
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The porosity and pore size distribution of shale within the oil window before and after solvent extraction are important for estimating the total oil content, understanding storage and migration pathways, and the location and acce...
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The porosity and pore size distribution of shale within the oil window before and after solvent extraction are important for estimating the total oil content, understanding storage and migration pathways, and the location and accessibility of hydrocarbons. However, the changes in porosity and pore size distribution of shale before and after extraction are complicated, and the mechanism is not well understood. The x-ray diffraction, Rock-Eval pyrolysis, field-emission scanning electron microscopy, and low-pressure gas adsorption were conducted to investigate the geochemistry and pore structures of extracted and nonextracted shale samples from the Yanchang Formation in the Ordos Basin, China. The extractable organic matter (EOM) in the samples includes hydrocarbons in pores and adsorbed on organic matter (OM) and minerals, and soluble porous or nonporous solid OM. The total pore volume and specific surface area (SSA) generally increased in the extracted samples. However, decreased pore volume at some pore size ranges in several extracted samples was observed, and there were differences in the incremental pore volume, SSA, and pore size distributions. The removal of liquid hydrocarbons from organic or inorganic pores, adsorbed EOM, and soluble porous or nonporous solid OM causes differences in changes in pore volume, SSA, and pore size distribution. The fractions of adsorbed EOM and soluble porous and nonporous, solid OM should be subtracted to avoid overestimating the total oil content. The inorganic pores and siltstone and sandstone laminae may play an important role in hydrocarbon storage and migration, which may be underestimated.
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In photovoltaic technologies, perovskite solar cells (PSCs) have gained significant consideration due to their attractive properties such as high absorption coefficient, long charge carrier diffusion length, easy solution processa...
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In photovoltaic technologies, perovskite solar cells (PSCs) have gained significant consideration due to their attractive properties such as high absorption coefficient, long charge carrier diffusion length, easy solution processability, and growth into one of the important classes of low-cost and easily scalable photovoltaic devices. Moreover, to further enhance the photovoltaic performance and make stable PSCs, fluorine substituted organic materials are widely employed. The first main reason is that fluorinated organic materials have higher hydrophobicity, which can effectively enhance the humidity stability of PSCs. The other reason is that fluorine substitution in organic materials is reported to be an effective way to regulate the energy level alignment, optimize perovskite film morphology, passivate the surface and boundary defects, and enhance the device performance. This review endeavours to illustrate the fluorine substitution in organic cation of perovskite precursors and their interfacial engineering through fluorinated dopants/additives. Moreover, the review covers the effect of fluorine substitution in the hole transporting layers (HTLs), electron transporting layers (ETLs), and fluorinated organic small molecules as dopant/additives into HTLs and their chemical interactions between the perovskite layer. We discussed the relationship between chemical structures, photophysical, electrochemical properties, and their photovoltaic performance in each part.
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Electric vehicles (EVs) are a promising option to reduce air pollution and shipping costs, especially in urban areas. To provide scientific guidance for the growing number of logistics companies using EVs, we investigated an elect...
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Electric vehicles (EVs) are a promising option to reduce air pollution and shipping costs, especially in urban areas. To provide scientific guidance for the growing number of logistics companies using EVs, we investigated an electric-vehicle-routing problem with simultaneous pickup and delivery that also considers non-linear charging and load-dependent discharging (EVRPSPD-NL-LD). The objective was to minimize the total number of EVs and the total working time, including travel time, charging time, waiting time, and service time. We formulated the problem as a mixed integer linear program (MILP), and small-size problems could be solved to optimality in an acceptable amount of time using the commercial solver IBM ILOG CPLEX Optimization Studio (CPLEX). In view of the fact that the problem is NP-hard, an adaptive large neighborhood search (ALNS) metaheuristic method was proposed to solve large-size problems. Meanwhile, new operators and a time priority approach were developed to provide options for different scenarios. The results of our computational investigation and sensitivity analysis showed that the proposed methods are effective and efficient for modified benchmark instances.
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This study investigates the degradation characteristics, bacterial community structure, and degradation mechanism of rice straw under different levels of nitrogen (N) application and depths of return of 1-mature-winter tillage in ...
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This study investigates the degradation characteristics, bacterial community structure, and degradation mechanism of rice straw under different levels of nitrogen (N) application and depths of return of 1-mature-winter tillage in paddy fields in a cold zone from the perspective of biodegradation by using the nylon mesh bag in situ culture method. Paludibacteraceae and Ruminococcaceae were the dominant bacteria in the degradation process, and their abundance decreased with the increasing depth of return. The activities of extracellular enzymes associated with the C-cycle (α-glucosidase, β-glucosidase, β-cellobiosidase, and β-xylosidase) were generally higher than those of other functional extracellular enzymes, and straw degradation extracellular enzyme activities generally increased in the middle and late stages (104 d). At an N application rate of 110–150 kg hm?2, the potential functionality of soil showed a quadratic trend with the increasing N application. When the full amount of straw was returned to the field, there was significant spatial heterogeneity in soil potential functionality. Our results showed that the most optimum N application rate was 140 kg hm?2, while the best soil return level (0–15 cm) was observed in the tillage layer under full rice straw return in the cold zone.
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