•Three types of hybrid nanofluids, composite, Janus and dual nanofluid, have been studied by MD.•The highest TC of composite nanofluids in mono-particle system is attributed to Brownian motion.•Why a ...moderate DOL has a larger TC is discussed.•Enhanced reliability of TC results is achieved from the multi-particle systems including >32 nanoparticles.
More and more applications of hybrid nanofluids are emerging in various fields such as energy engineering, chemical engineering, and automotive engineering. However, the existing literature only employs the term "synergistic effect" to explain the improvement of thermal conductivity of hybrid nanofluids. In order to elucidate the underlying reasons behind the improvement in thermal conductivity of hybrid nanofluids compared to that of conventional ones (mono nanofluids), molecular dynamics simulations were conducted to examine three types of hybrid nanofluids, including Ag-Cu nanocomposites, Au-Cu Janus nanoparticles, and Ag-Cu binary nanoparticles. The results suggest that hybrid nanofluids including Ag-Cu nanocomposites, Au-Cu Janus nanoparticles, and Ag-Cu binary nanoparticles improve the thermal conductivity of 2 vol% nanofluid by 34.3 %, 12.1 %, and 10.4 %, respectively, compared to Cu monofluid. The improvement in thermal conductivity for hybrid nanofluids containing nanocomposites in single-particle systems can be attributed primarily to the stronger Brownian motion, while the improvement in thermal conductivity for hybrid nanofluids containing Au-Cu Janus nanoparticles and Ag-Cu binary nanoparticles is due to the looser aggregation morphology in multi-particle systems. This observation allows us to appreciate the significance of aggregation morphology as a crucial mechanism when considering interactions between nanoparticles. It provides a theoretical basis for the preparation of high-performance nanofluids as heat transfer media.
Coal and carbonaceous shale samples were taken from the Late Oligocene Bobov Dol Basin, SW Bulgaria. Seams Ia, I, IIa+b, III, IV and V from the coal-bearing Bobov Dol Fm. were sampled to provide ...insights into the peat forming vegetation and depositional environment based on detailed organic petrological and geochemical study.
The petrographic composition indicates that both coals and carbonaceous shales contain predominantly terrestrial organic matter with abundant huminite macerals and locally enriched liptinite macerals. Inertinite is rare or absent. Good tissue preservation in seams I, IV and V indicates deposition under wet sedimentary environment, whereas predominance of detrohuminite and lower Tissue Preservation Index (TPI) in seams Ia, IIa+b and III are linked to enhanced humification of the plant remains due to changes in the hydrological regime. The low percent of inertinite and the overall high Gelification Index (GI), however, argue for peat formation under wetter climatic settings, whereas low to moderate ash yields of coal samples indicate organic matter deposition in oligo- to mesotrophic topogenous mires. Reconstructed evolution of the environmental settings during peat formation denotes differences which might be caused by changes in the hydrological regime and tectonic activity.
The biomarker composition shows prevalence of gymnosperm-derived sesqui- and diterpenoids, followed by lower concentration of n-alkanes (apart from the carbonaceous shale samples from seam Ia), whereas angiosperm-derived non-hopanoid triterpenoids, acyclic isoprenoids, steroids and hopanoids, are generally present in minor amounts. Diterpenoid composition indicates dominant contribution from Cupressaceae and Pinaceae conifers. Minor amounts of predominantly lupane-type non-hopanoid triterpenoids denote limited development of angiosperm vegetation, presumably mostly related to Betulaceae family. Relative abundance of mid-chain (n-C21–25) n-alkanes, associated with elevated proxy ratio (Paq) furthermore, suggest possible contribution from aquatic macrophytes to peat formation. Very low hopane concentrations and low/moderate ββ/(ββ + αβ) hopane ratios imply minor aerobic bacterial activity under mild acidic conditions. The presence of inorganic carbon suggests that environmental acidity might be controlled by the occasional input of neutral to slightly alkaline ground waters. Moderate sulfur contents and the occurrence of hopenes denote anaerobic bacterial activity after organic matter burial.
Low maturity of the organic matter and limited hydrocarbon generation potential is indicated by the low huminite reflectance, hopane (C31 22S/(22S + 22R)) and sterane (αααC29 20S/(20S + 20R)) isomerization ratios, as well as Rock-Eval parameters, Tmax and Production Index (PI).
Display omitted
•Organic petrology and geochemistry of Oligocene Bobov Dol sub-bituminous coal, Bulgaria.•Biomarkers denote major input from gymnosperm vegetation with contribution from angiosperms and mesophytic plants.•Peat deposition processed within oligo- to mesotrophic topogenous mires.•Ash yields, tissue preservation and gelification are considered to reflect changes in hydrological regime.•Huminite reflectance and geochemical proxies denote low organic matter maturity.
In traditional in situ polymerization preparation for solid‐state electrolytes, initiators are directly added to the liquid precursor. In this article, a novel cellulose paper‐based composite ...separator is fabricated, which employs alumina as the inorganic reinforcing material and is loaded with polymerization initiator aluminum trifluoromethanesulfonate. Based upon this, a separator‐induced in situ directional polymerization technique is demonstrated, and the extra addition of initiators into liquid precursors is no longer required. The polymerization starts from the surface and interior of the separator and extends outward with the gradually dissolving of initiators into the precursor. Compared with its traditional counterpart, the separator‐induced poly(1,3‐dioxolane) electrolyte shows improved interfacial contact as well as appropriately mitigated polymerization rate, which are conducive to practical applications. Electrochemical measurement results show that the prepared poly(1,3‐dioxolane) solid electrolyte possesses an oxidation potential up to 4.4 V and a high Li+ transference number of 0.72. After 1000 cycles at 2 C rate (340 mA g−1), the assembled Li||LiFePO4 solid battery possesses a 106.8 mAh g−1 discharge capacity retention and 83.5% capacity retention ratio, with high average Coulombic efficiency of 99.5% achieved. Our work may provide new ideas for the design and application of in situ polymerization technique for solid electrolytes and solid batteries.
A separator‐induced in situ directional polymerization technique for the preparation of solid polymer electrolyte is demonstrated, and the extra addition of initiators into liquid precursors is no longer needed. The interfacial contact is further improved compared with the traditional method, and meanwhile mitigated polymerization rate is obtained.
Display omitted
•By division of labor, strains N5 and B9 greatly improved phenol degradation.•Expression of key genes involved in phenol degradation was changed in co-culture.•The strains in the ...co-culture regulated the expression of genes by reciprocities.•Synergistic regulation of gene expression promoted phenol degradation in co-culture.
The aim of this work is to study the synergistic effect of Stenotrophomonas sp. N5 and Advenella sp. B9 co-culture (COC) on enhancement of phenol biodegradation. These two strains utilizing phenol as sole carbon and energy source were isolated from phenol-containing coking wastewater. The results of biodegradation experiment showed the COC of N5 and B9 has stronger capability to degrade phenol than either of mono-culture (MOC). Growth kinetics studies indicated inhibitory effect of phenol on COC was reduced by the interaction of N5 and B9 in COC. The RNA-Seq results demonstrated that phenol biodegradation was enhanced by metabolic division of labor (DOL) in COC based on the expression of key genes for phenol degradation. GO enrichment analysis of differentially expressed genes (DEGs) indicated DEGs between COC and MOC degradation systems are mainly concentrated in the synthesis of cell components, microbial growth and metabolism, and catalytic activity. The expression of 3 transcriptional factors (LysR, Two-component system response regulator, and TetR families) which can regulate degradation of aromatic compounds, was identified beneficial to phenol degradation.
The nanoparticle aggregation is a crucial factor for the thermal conductivity of nanofluids based on previous researches. Molecular dynamics simulations for the nanofluids involving 4–32 Janus ...nanoparticles (termed as Janus nanofluid) were conducted. The thermal conductivity of the Janus nanofluid was found to be larger than that of the ordinary nanofluid, approximately 0.3707 W/m.K for Janus, compared to 0.3521 W/m.K for Au and 0.3303 W/m.K for Cu nanofluid. Further analysis shows that the aggregation morphology in the Janus nanofluid is different from that in the ordinary one. For the better evaluation of the aggregation morphology, a term named degree of looseness was introduced to replace fractal dimension. The relationship between thermal conductivity and degree of looseness shows that the thermal conductivity of the Janus nanofluid first rises and then decreases with the degree of looseness. When 18 nanoparticles are included in the simulated system, the maximum thermal conductivity is 0.3249 W/m.K for a moderate degree of looseness of 10.841 at 4 vol%. Finally, the underlying mechanism why the Janus nanofluid has a larger thermal conductivity than the ordinary one is discussed. This can provide a useful reference for preparing Janus nanofluids with larger thermal conductivity and understanding the underlying mechanisms.
Display omitted
•The TC of the Janus nanofluid is much larger than that of the ordinary one.•The DoL is a suitable metric to evaluate the TC of nanofluids in the hybrid morphology.•The coexistence of clusters and individual primary nanoparticles is responsible for the greater TC.•The greatest TC of the Janus nanofluid appears at a moderate DoL.•A comprehensive discussion of the mechanisms responsible for higher TC is presented.
•Long-term mechanical properties of BS including the duration of load (DOL) and creep effects were investigated.•The DOL effect of BS was more severe than that of other structural wooden ...materials.•The time-dependent constitutive models of DOL and creep effects for BS were developed.
Bamboo scrimber (BS), a main bamboo composite, has wide application prospects in green buildings. As a viscoelastic biomass material, long-term mechanical properties are the key indicators for its safe lifetime service. In this study, both short-term and long-term tension tests parallel to grain of BS were conducted. The long-term mechanical properties of BS including the duration of load (DOL) and creep effects were investigated from the macro and micro levels. Results indicated that the DOL effect of BS was more severe than other structural wooden materials, but its relative creep strain was smaller. From microlevel characterization, the DOL effect was strongly correlated with its microfracture morphology and bamboo fiber damage, while the creep effect was related to the decomposition of hemicellulose. Finally, time-dependent constitutive models were developed and provided good prediction for the DOL factor and creep strain of BS under different load durations. This study was beneficial for the long-term safe application of BS as a new structural material.
Conventional engineered wood and bamboo materials commonly require organic adhesives for adequate bonding. As an alternative solution in bio-based composites, a novel bamboo-based composite prepared ...with a magnesium-based inorganic adhesive was proposed herein, which is named as “inorganic-bonded bamboo composite” and abbreviated as InorgBam. This study investigates the duration of load (DOL) effect on InorgBam beams under long-term flexural load. The percentile matching method was used to obtain the short-term strengths matched to the long-term specimens, and the strength reduction of the long-term specimens was obtained. The DOL result were calibrated using the DOL empirical formulas and DOL damage models, including Gerhards, Foschi and Yao, and Nielsen models. The impact of the selected cumulative probability functions of short-term strength on the DOL analysis has also been discussed. Results illustrated that the strength reduction in the InorgBam was less than the prediction of Madison curve. The value of DOL coefficient determined with Foschi and Yao model was closest to that derived from the empirical fitted formula. The DOL effect of the InorgBam beams was significantly smaller than that of conventional engineered wood beams, which is beneficial for determining the design strength value of InorgBam material.
•An InorgBam composed of magnesium-based inorganic adhesive and bamboo was proposed.•The duration of load (DOL) effect of InorgBam under flexural loading was investigated.•Empirical formulas and DOL models were calibrated to evaluate DOL effect of InorgBam.•DOL coefficient of InorgBam was compared to structural woods.
•NDT methods are useful in the process of historical facilities’ condition assessment.•Wooden structures should be analyzed in terms of rheology and joints degradation.•DOL effect should be ...considered during wooden structures assessment.•In long wooden elements, the material parameters vary along the element's length.•In carpentry joint structures, support parameters should be determined iteratively.
Deformation of wooden roof structures is the effect of strength parameters reduction caused by biological corrosion, passage of time, looseness in joints and assembly inaccuracies. It is a significant problem, especially in buildings built several hundred years ago. Over many years of operation, historical structures are exposed to various loads, not only from their own weight or from external environmental influences (wind, snow). There are also accidental loads such as fires or warfare. Repairs and reconstructions, carried out as a result of accidental damages, are also important for the building structure. Renovation processes often influence on changes in the static scheme of the originally constructed structural system. Rheological phenomena of structural elements and joints have a significant impact on the redistribution of internal forces.
In the paper the thorough condition evaluation of the historical church building is presented. The evaluation is performed with the use of non-destructive testing (NDT) methods. The analyzed church building was built in 1579–1601. Throughout its history, it was rebuilt after a fire when the structure of the roof and ceiling above the main nave was reconstructed. Then the roof covering was changed from heavy ceramic tiles to light sheet metal covering, and finally the sheet metal was replaced with metal roof tiles. In the meantime, the roof structure suffered damage resulting from the war, and a part of the roof structure had to be replaced. The current condition of the roof truss was analyzed using finite element method (FEM) software. The influence of the condition of carpentry joints on the deformation of the roof truss was analyzed. The duration of load (DOL) effect on the deformation of structural elements, as well as the influence of biological corrosion and uneven distribution of wood strength parameters in individual structural elements were considered. Based on the presented detailed analysis of the condition of the historic wooden structure using NDT methods, suggestions regarding the general applicable area in historic structures were formulated.
Secondary minerals could be effective scavengers of toxic arsenic (As) and thallium (Tl). In environments polluted by mining, these elements are abundant both in acid rock/mine drainage scenarios, as ...well as in carbonate-buffered environments. In this study we have investigated the behavior of As and Tl during weathering in mine waste dumps and an associated technosol sample from the Crven Dol locality (Allchar Tl–As–Sb–Au deposit, North Macedonia) contaminated with up to 142 g kg−1 of As and 18 g kg−1 of Tl, making it an As- and Tl-extreme environment. We identified As and Tl reservoirs and discuss their difference from those observed in other naturally As- and Tl-rich environments. The pore waters show high concentrations of As (up to 196 mg L−1) and Tl (up to 660 μg L−1). Mild extractions mobilized up to 46% of the total Tl and 11% of the total As, indicating that a large amount of these toxic elements is weakly bound and can be easily mobilized into the environment. Apart from the recognition of Tl storage in several secondary phases (mainly as Tl(I) in members of the pharmacosiderite and jarosite groups, as well as Mn oxides, but also as very minor Tl(III) in other secondary phases), this study also provides the first evidence of Tl uptake by previously unknown thallium arsenate phases (with Tl:As ratios ∼ 2 and 4), detected in carbonate-buffered (near-neutral pH) As- and Tl-rich technosols and waste dumps. These results indicate the need for further studies on Tl speciation in extremely As- and Tl-rich environments.
Display omitted
•We study Tl and As retention in secondary minerals.•Pronounced Tl-concentrations: up to 18 g kg−1.•Tl is precipitated mostly as novel thallium arsenates and as dorallcharite.•Significant amount of As and Tl is bound weakly to solids.•Large quantity of As and Tl can be easily mobilized into the pore water and biota.
PDF