Efficient catalysts are indispensable for overcoming the sluggish reaction kinetics and high overpotentials inherent in Li-O batteries. However, the lack of precise control over catalyst structures at the atomic level and limited understanding of the underlying catalytic mechanisms pose significant challenges to advancing catalyst technology. In this study, we propose the concept of precisely controlled pre-lithiated electrocatalysts, drawing inspiration from lithium electrochemistry.
View Article and Find Full Text PDFThe molecular-level details of the formation of mixed gas hydrates remain elusive despite their significance for a variety of scientific and industrial applications. In this study, extensive molecular simulations have been performed to examine the behavior of CH/HS mixed hydrate nucleation utilizing two different simulation setups varying in compositions and temperatures. The observed behavior exhibits similar phenomenology across the various systems once differences in nucleation rates and guest uptake are accounted for.
View Article and Find Full Text PDFAeolian sediment emission from surfaces and subsequent transport are important geological processes. The Tibet Plateau experiences strong aeolian activity in areas such as the Yarlung Zangbo River basin. The dust storms have caused grounding of aircraft, highway closures, and other consequences for the region's residents.
View Article and Find Full Text PDFThe commercial use of natural methane hydrate is hampered by several open questions that remain regarding hydrate formation. Here the authors comment on past interpretations and aim to provide a roadmap for developing a predictive theory of methane hydrate nucleation.
View Article and Find Full Text PDFWind erosion has gained increasing attention as one of the most serious global ecological and environmental threats. Windbreaks are effective at decreasing wind erosion by reducing wind speed to protect crops, livestock, and farmsteads, while providing wildlife habitats. Synthetic shrubs can act as novel windbreaks; however, there is limited knowledge on how their design affects wind speed.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
June 2019
Crystallization in liquids is critical to a range of important processes occurring in physics, chemistry and life sciences. In this article, we review our efforts towards understanding the crystallization mechanisms, where we focus on theoretical modelling and molecular simulations applied to ice and gas hydrate systems. We discuss the order parameters used to characterize molecular ordering processes and how different order parameters offer different perspectives of the underlying mechanisms of crystallization.
View Article and Find Full Text PDFThe broad scientific and technological importance of crystallization has led to significant research probing and rationalizing crystal nucleation processes. Previous work has generally neglected the possibility of the molecular-level dynamics of individual crystal nuclei coupling to local structures. However, recent experimental work has conjectured that this can occur.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2018
By investigating the aqueous solution properties of several hydrate guests with molecular simulations, we find that with increasing guest concentration, the guest's hydration shell becomes more ordered and the system entropy decreases. A common critical value of the self-diffusion coefficient of different guest molecules is identified, below which hydrates will nucleate very readily.
View Article and Find Full Text PDFWe calculated methane transport through cylindrical graphite nanopores in cyclical steady-state flows using non-equilibrium molecular dynamics simulations. First, two typical gas reservoir configurations were evaluated: open (OS) and closed (CS) systems in which pores connect to the gas reservoir without/with a graphite wall parallel to the gas flow. We found that the OS configuration, which is commonly used to study nanoflows, exhibited obvious size effects.
View Article and Find Full Text PDFPhys Chem Chem Phys
July 2017
Although ice powders are widely used in gas hydrate formation experiments, the effects of ice on hydrate nucleation and what happens in the quasi-liquid layer of ice are still not well understood. Here, we used high-precision constant energy molecular dynamics simulations to study methane hydrate nucleation from vapor-liquid mixtures exposed to the basal, prismatic, and secondary prismatic planes of hexagonal ice (ice Ih). Although no significant difference is observed in hydrate nucleation processes for these different crystal planes, it is found, more interestingly, that methane hydrate can nucleate either on the ice surface heterogeneously or in the bulk solution phase homogeneously.
View Article and Find Full Text PDFThe molecular-level details of mixed hydrate nucleation remain unclear despite the broad implications of this process for a variety of scientific domains. Through analysis of mixed hydrate nucleation in a prototypical CH/HS/HO system, we demonstrate that high-level kinetic similarities between mixed hydrate systems and corresponding pure hydrate systems are not a reliable basis for estimating the composition of early stage mixed hydrate nuclei. Moreover, we show that solution compositions prior to and during nucleation are not necessarily effective proxies for the composition of early stage mixed hydrate nuclei.
View Article and Find Full Text PDFBy performing molecular dynamics simulations to form a hydrate with a methane nano-bubble in liquid water at 250 K and 50 MPa, we report how different ensembles, such as the NPT, NVT, and NVE ensembles, affect the nucleation kinetics of the methane hydrate. The nucleation trajectories are monitored using the face-saturated incomplete cage analysis (FSICA) and the mutually coordinated guest (MCG) order parameter (OP). The nucleation rate and the critical nucleus are obtained using the mean first-passage time (MFPT) method based on the FS cages and the MCG-1 OPs, respectively.
View Article and Find Full Text PDFThe results of six high-precision constant energy molecular dynamics (MD) simulations initiated from methane-water systems equilibrated at 80 MPa and 250 K indicate that methane hydrates can nucleate via multiple pathways. Five trajectories nucleate to an amorphous solid. One trajectory nucleates to a structure-I hydrate template with long-range order which spans the simulation box across periodic boundaries despite the presence of several defects.
View Article and Find Full Text PDFHuan Jing Ke Xue
February 2013
There are lots of dust deposition collection methods on dust deposition, but there is no standard field observation method. At present, researchers have studied dust deposition using different methods in this issue, but due to the different observation method and collection efficiency, the research results are incomparable. The efficiency of the standard dust deposition gauge including dry, wet, net, net and glass ball and slowing speed methods was studied in the Tengger Desert.
View Article and Find Full Text PDFObjectives: The authors investigate whether the combination of anti-CD34 antibody with DES is win-win cooperation.
Background: DES may reduce the risk of restenosis compared to bare-metal stents (BMS), but they were found to inhibit the healing process of intima.
Methods: Fifteen BMS, 17 DES, and 16 combined anti-CD34 antibody and DES were randomly implanted in the coronary arteries of 22 minipigs.
J Biomed Mater Res A
September 2011
This study is designed to make a novel cell seeding stent and to evaluate reendothelialization and anti-restenosis after the stent implantation. In comparison with cell seeding stents utilized in previous studies, Mesenchymal stem cells (MSCs) have advantages on promoting of issue repair. Thus it was employed to improve the reendothelialization effects of endovascular stent in present work.
View Article and Find Full Text PDFN-tert-Butyl-N,N'-diacylhydrazines are nonsteroidal ecdysone agonists used as environmental benign pest regulators. In this paper, two series of new N-tert-butyl-N,N'-diacylhydrazine derivatives containing 1,2,3-thiadiazole were designed and synthesized. All structures of the synthesized compounds were confirmed by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS).
View Article and Find Full Text PDFZhongguo Yi Liao Qi Xie Za Zhi
November 2005
The development of drug eluting-stents has been a breakthrough for the prevention of PCI postoperative restenosis, and the correlative researches have not yet stopped and are still the focus of the world. We review, in this article, the history of drug eluting-stents researches, analyze the research actualities and the problems existing, and forecast the developing trend in the future.
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