David Seus  Florin A. Radu  Christian Rohde 《Numerical Methods for Partial Differential Equations》2023,39(1):622-656

The viscous flow of two immiscible fluids in a porous medium on the Darcy scale is governed by a system of nonlinear parabolic equations. If infinite mobility of one phase can be assumed (e.g., in soil layers in contact with the atmosphere) the system can be substituted by the scalar Richards model. Thus, the porous medium domain may be partitioned into disjoint subdomains where either the full two-phase or the simplified Richards model dynamics are valid. Extending the previously considered one-model situations we suggest coupling conditions for this hybrid model approach. Based on an Euler implicit discretization, a linear iterative (L-type) domain decomposition scheme is proposed, and proved to be convergent. The theoretical findings are verified by a comparative numerical study that in particular confirms the efficiency of the hybrid ansatz as compared to full two-phase model computations.  相似文献   

    

Nedić Vasiljević  Bojana  Jovanović  Aleksandar Z.  Mentus  Slavko V.  Skorodumova  Natalia V.  Pašti  Igor A. 《Journal of Solid State Electrochemistry》2023,27(7):1877-1887

Journal of Solid State Electrochemistry - The growing energy crisis put an emphasis on the development of novel efficient energy conversion and storage systems. Here we show that surface...  相似文献   

    

Dr. Uvinduni I. Premadasa  Dr. Vera Bocharova  Audrey R. Miles  Diana Stamberga  Stella Belony  Dr. Vyacheslav S. Bryantsev  Adnan Elgattar  Prof. Yi Liao  Dr. Joshua T. Damron  Dr. Michelle K. Kidder  Dr. Benjamin Doughty  Dr. Radu Custelcean  Dr. Ying-Zhong Ma 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304957

One of the grand challenges underlying current direct air capture (DAC) technologies relates to the intensive energy cost for sorbent regeneration and CO₂ release, making the massive scale (GtCO₂/year) deployment required to have a positive impact on climate change economically unfeasible. This challenge underscores the critical need to develop new DAC processes with substantially reduced regeneration energies. Here, we report a photochemically-driven approach for CO₂ release by exploiting the unique properties of an indazole metastable-state photoacid (mPAH). Our measurements on simulated and amino acid-based DAC systems revealed the potential of mPAH to be used for CO₂ release cycles by regulating pH changes and associated isomers driven by light. Upon irradiating with moderate intensity light, a ≈55 % and ≈68 % to ≈78 % conversion of total inorganic carbon to CO₂ was found for the simulated and amino acid-based DAC systems, respectively. Our results confirm the feasibility of on-demand CO₂ release under ambient conditions using light instead of heat, thereby providing an energy efficient pathway for the regeneration of DAC sorbents.  相似文献   

    

Barbu Cristian Braun  Corneliu Nicolae Drug&#x;  Ionel erban  Diana Cotoros  Necula Radu 《Macromolecular Symposia》2020,389(1)

The paper presents a series of aspects regarding the main biotribological phenomena occurring in the synovial joints. Although a great deal of research is carried out around the world about the biotribological processes in the human body's synovial joints, due to their complexity, they are not yet been fully understood and cannot establish a unique model of lubrication mechanism in these joints. The problem is complicated by the fact that in reality the cartilage is neither homogeneous nor isotropic and undergoes a large deformation during loading. According to several researchers, implantation and expulsion of synovial fluid in cartilage is not a simple phenomenon, although the boosted or weeping type of lubrication suggests this. The self‐generating lubrication mechanism postulated by Mow et al. (1987) takes into account the biphasic nature of cartilage and is based on the load‐dividing factor between the solid phase and the liquid. In recent years, studies have also been carried out to explore possible links between synovial joint lubrication mechanisms and degeneration processes. Tribological modeling is based on a number of parameters, such as: lubricant film thickness (or synovial fluid), maximum physiological load, articular cartilage surface roughness, friction coefficient, surface roughness, and lubrication regime.  相似文献   

    

Cristiana Radulescu  Radu Lucian Olteanu  Claudia Stihi  Monica Florescu  Raluca Maria Stirbescu  Sorina Geanina Stanescu  Cristina Mihaela Nicolescu  Marius Bumbac 《Journal of Chemometrics》2020,34(6):e3234

In this study, the chemical composition of Juglandis semen extracts obtained by different extraction solvents and methods were determined by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The multivariate analyses, principal component analysis and hierarchical cluster analysis of the FTIR and Raman spectral datasets, were performed to determine the differences in the chemical composition according to the solvent (e.g., mixture of water with alcohol, glycerole, and propylene glycol) and the extraction method (i.e., ultrasound-assisted extraction, rapid pressurized extraction, and subcritical fluid extraction). The obtained results reveal that the J. semen extracts with water-alcohol solvent have equivalent chemical composition. A well-defined differentiation based on extraction method could not be highlighted. Based on FTIR data compilation, it can be observed that a first classification can be made based on the solvent, acidic or basic, used for extraction methods (except subcritical fluid extraction - SFE, clustering is clearly assigned by the solvent). Multivariate analysis on FTIR and Raman spectral data was able to differentiate SFE extract as a unique cluster, which means HFC134a solvent allowed a specific extraction (from organic constituents' point of view) due to the selected conditions of extraction method.  相似文献   

    

Fahrettin Sarcan  Sam Orchard  Balati Kuerbanjiang  Aleksandar Skeparovski  Vlado K. Lazarov  Ayse Erol 《固体物理学:研究快报》2020,14(8)

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Adriana Cecilia Csakvari  Cristian Moisa  Dana G. Radu  Leonard M. Olariu  Andreea I. Lupitu  Anca Ofelia Panda  Georgeta Pop  Dorina Chambre  Vlad Socoliuc  Lucian Copolovici  Dana Maria Copolovici 《Molecules (Basel, Switzerland)》2021,26(13)

Cannabis sativa L. (hemp) is a plant used in the textile industry and green building material industry, as well as for the phytoremediation of soil, medical treatments, and supplementary food products. The synergistic effect of terpenes, flavonoids, and cannabinoids in hemp extracts may mediate the biogenic synthesis of metal nanoparticles. In this study, the chemical composition of aqueous leaf extracts of three varieties of Romanian hemp (two monoecious, and one dioecious) have been determined by Fourier-Transformed Infrared spectroscopy (FT-IR), high-performance liquid chromatography, and mass spectrometry (UHPLC-DAD-MS). Then, their capability to mediate the green synthesis of silver nanoparticles (AgNPs) and their pottential antibacterial applications were evaluated. The average antioxidant capacity of the extracts had 18.4 ± 3.9% inhibition determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) and 78.2 ± 4.1% determined by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS™) assays. The total polyphenolic content of the extracts was 1642 ± 32 mg gallic acid equivalent (GAE) L⁻¹. After this, these extracts were reacted with an aqueous solution of AgNO₃ resulting in AgNPs, which were characterized by UV−VIS spectroscopy, FT-IR, scanning electron microscopy (SEM-EDX), and dynamic light scattering (DLS). The results demonstrated obtaining spherical, stable AgNPs with a diameter of less than 69 nm and an absorbance peak at 435 nm. The mixture of extracts and AgNPs showed a superior antioxidant capacity of 2.3 ± 0.4% inhibition determined by the DPPH^• assay, 88.5 ± 0.9% inhibition as determined by the ABTS^•+ assay, and a good antibacterial activity against several human pathogens: Escherichia coli, Klebsiella pneumoniae, Pseudomonas fluorescens, and Staphylococcus aureus.  相似文献   

    

Sara Nasiri Sovari  Isabelle Kolly  Kevin Schindler  Youri Cortat  Shing-Chi Liu  Aurelien Crochet  Aleksandar Pavic  Fabio Zobi 《Molecules (Basel, Switzerland)》2021,26(17)

The reaction of rhenium α-diimine (N-N) tricarbonyl complexes with nitrosonium tetrafluoroborate yields the corresponding dicarbonyl-nitrosyl [Re(CO)₂(NO)(N-N)X]⁺ species (where X = halide). The complexes, accessible in a single step in good yield, are structurally nearly identical higher charge congeners of the tricarbonyl molecules. Substitution chemistry aimed at the realization of equivalent dicationic species (intended for applications as potential antimicrobial agents), revealed that the reactivity of metal ion in [Re(CO)₂(NO)(N-N)X]⁺ is that of a hard Re acid, probably due to the stronger π-acceptor properties of NO⁺ as compared to those of CO. The metal ion thus shows great affinity for π-basic ligands, which are consequently difficult to replace by, e.g., σ-donor or weak π-acids like pyridine. Attempts of direct nitrosylation of α-diimine fac-[Re(CO)₃]⁺ complexes bearing π-basic OR-type ligands gave the [Re(CO)₂(NO)(N-N)(BF₄)][BF₄] salt as the only product in good yield, featuring a stable Re-FBF₃ bond. The solid state crystal structure of nearly all molecules presented could be elucidated. A fundamental consequence of the chemistry of [Re(CO)₂(NO)(N-N)X]⁺ complexes, it that the same can be photo-activated towards CO release and represent an entirely new class of photoCORMs.  相似文献   

    

Tapan Behl  Tanuj Upadhyay  Sukhbir Singh  Sridevi Chigurupati  Amal M. Alsubayiel  Vasudevan Mani  Celia Vargas-De-La-Cruz  Diana Uivarosan  Cristiana Bustea  Cristian Sava  Manuela Stoicescu  Andrei-Flavius Radu  Simona Gabriela Bungau 《Molecules (Basel, Switzerland)》2021,26(21)

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Aleksandar Radivojac  Oskar Bera  Zoran Zekovi&#x;  Nemanja Tesli&#x;   ivan Mrkonji&#x;  Danijela Bursa&#x; Kova evi&#x;  Predrag Putnik  Branimir Pavli&#x; 《Molecules (Basel, Switzerland)》2021,26(10)

Consumers are becoming more mindful of their well-being. Increasing awareness of the many beneficial properties of peppermint essential oil (EO) has significantly increased product sales in recent years. Hydrodistillation (HD), a proven conventional method, and a possible alternative in the form of microwave-assisted hydrodistillation (MWHD) have been used to isolate peppermint EO. Standard Soxhlet and alternatively supercritical fluid (SFE), microwave-assisted, and ultrasound-assisted extraction separated the lipid extracts. The distillations employed various power settings, and the EO yield varied from 0.15 to 0.80%. The estimated environmental impact in terms of electricity consumption and CO₂ emissions suggested that MWHD is an energy efficient way to reduce CO₂ emissions. Different extraction methods and solvent properties affected the lipid extract yield, which ranged from 2.55 to 5.36%. According to the corresponding values of statistical parameters, empiric mathematical models were successfully applied to model the kinetics of MWHD and SFE processes.  相似文献