Добірка наукової літератури з теми "MNM3D"

Humic acid-coated goethite nanoparticles (HA-GoeNPs) have been recently proposed as an effective reagent for the in situ nanoremediation of contaminated aquifers. However, the effective dosage of these particles has been studied only at laboratory scale to date. This study investigates the possibility of using HA-GoeNPs in remediation of real field sites by mimicking the injection and transport of HA-GoeNPs under realistic conditions. To this purpose, a three-dimensional (3D) transport experiment was conducted in a large-scale container representing a heterogeneous unconfined aquifer. Monitoring data, including particle size distribution, total iron (Fetot) content and turbidity measurements, revealed a good subsurface mobility of the HA-GoeNP suspension, especially within the higher permeability zones. A radius of influence of 2 m was achieved, proving that HA-GoeNPs delivery is feasible for aquifer restoration. A flow and transport model of the container was built using the numerical code Micro and Nanoparticle transport Model in 3D geometries (MNM3D) to predict the particle behavior during the experiment. The agreement between modeling and experimental results validated the capability of the model to reproduce the HA-GoeNP transport in a 3D heterogeneous aquifer. Such result confirms MNM3D as a valuable tool to support the design of field-scale applications of goethite-based nanoremediation.

The aim of this study was to explore the differences in metabolites related to rice quality formation under different nitrogen (N) fertilizers and planting densities. In this study, Yangnongxiang 28 was used as the experimental material with the following conditions: high nitrogen and low density (HNLD; high nitrogen: 360 kg·hm−2, low density: the row spacing of rice plants was 16 cm × 30 cm), medium nitrogen and medium density (MNMD; medium nitrogen: 270 kg·hm−2, medium density: the row spacing of rice plants was 13 cm × 30 cm), and low nitrogen and high density (LNHD; low nitrogen: 270 kg·hm−2, high density: the row spacing of rice plants was 10 cm × 30 cm). The rice quality indexes, including the processing quality, amylose content, and taste value, were compared under different treatments, and we analyzed their relationship with the metabolites. The results show that the milled rice rate of HNLD was 13.85% and was 1.89% higher than that of LNHD and MNMD, respectively. The head milled rice rate of HNLD was 32.45% and 6.39% higher than that of LNHD and MNMD, respectively. The milled rice rate and head milled rice rate of HNLD and MNMD were significantly higher than those of LNHD. This study identified 22 differential metabolites (DMs) in HNLD and LNHD, 38 DMs in HNLD and MNMD, and 23 DMs in LNHD and MNMD. Most of the identified differential metabolites were lipid metabolites, which were mainly enriched in the lipid metabolic pathways and amino acid metabolic pathways. The correlation analysis showed that the lipid metabolite physapubescin was significantly negatively correlated with the taste value. The lipid metabolites 2-undecen-1-ol, lucidenic acid F, and 8-deoxy-11,13-dihydroxygrosheimin were significantly positively correlated with the taste value. Lipids may be important substances that lead to differences in taste under different nitrogen fertilizer and density treatments.

Resistivityvs. temperature and valence band spectra of (La_0.6Pr_0.4)_0.65Ca_0.35MnO₃nanoparticles have been shown in figures. This figure clearly shows the hybridization of Mn3d(t_2g) and O2p states.

This study was aimed at investigating the effect of the bone compositions on the fracture toughness of bovine cortical bone. A series of the SENB bovine cortical bone specimens were tested to assess the fracture toughness. Dual energy X-ray absorptiometry (DEXA) was applied to determine the mineral content of each bovine cortical specimen and hence the porosity and bone mineral fraction were measured. Current results indicate that the mean value fracture toughness is 9.37 MNm3/2. Moreover, the fracture toughness was found to be significantly correlated with the apparent wet bone density and porosity of bone structure. No apparent correlations are found among clinical BMD and mechanical properties, implying that the BMD is an invalid indicator of the bone properties. Additionally, the tested data were fitted to the relationship, based on power law model, that the fracture toughness increase as a power (1.526) of increasing volume fraction and as a power of increasing bone mineral fraction (0.8195). These data indicate that small changes in the amount or density of compact bone tissue exert a more pronounced influence on fracture property.

Cheese whey (CW) and hemp hurds (HH) represent typically overabundant biowastes of food and agricultural production, and their circular management is crucial to improve both sustainability and profitability of the agri-food chain. By combining experimental biochemical methane potential (BMP) tests and literature data, the techno-economic aspects of a possible future bioenergy valorization of CW and HH through anaerobic digestion (AD) and co- digestion (coAD) were analyzed. Along the 42-days, BMP assays, CW, and HH alone rendered BMP values of 446 ± 66 and 242 ± 13 mL CH4·g VS−1, respectively. The application of coAD with CW and HH at a 70:30 ratio allowed to enhance the biomethane production by 10.7%, as compared to the corresponding calculated value. In terms of economic profitability, the valorization of HH as biomethane in a dual-purpose hemp cultivation could potentially enable net profits of up to 3929 €·ha−1, which could rise to 6124 €·ha−1 in case of coAD with CW. Finally, by projecting the biomethane potential from current and future available CW and HH residues in the national context of Italy, a total biomethane yield of up to 296 MNm3·y−1 could be attained, offering interesting perspectives for the sustainability of key sectors such as transportation.

ABSTRACTElectronic structure of Mn/ZnO system has been investigated by synchrotron radiation photoemission. Manganese vacuum deposition was done at room temperature onto a ZnO(0001) single crystal for coverage ΘMn < 4 ML. Photoemission spectra taken near Mn3p-Mn3d absorption edge after each deposition step show resonant enhancement of Mn3d states within 10 eV of the Fermi level. The experimentally deduced partial Mn3d density of states for Θ > 1.2 ML shows at least three features: a major Mn3d structure at 3.8–4.5 eV below the Fermi energy, a valence structure at lower binding energy (1–3 eV) and a broad satellite in the 5.5 – 9 eV range. The branching ratio of satellite/main structure increases with deposition from 0.33 for 0.4 ML to 0.65 for 4 ML. After annealing up to 500 C the satellite/main ratio decreases to 0.43 indicating a high degree of hybridization between the Mn3d states and valence band of ZnO. After annealing no manganese cap layer was found at the crystal surface as was confirmed by the lack of metallic Fermi edge in photoemission spectra and by scanning Auger spectroscopy experiment. The photoemission Mn3p core level spectra taken after annealing consist of two components separated by about 4eV. It is evidence that at least two manganese states are observed in the Mn-ZnO interface region.

The understanding of fate and transport of nanoparticles (NPs) in groundwater has become a significant environmental issue in the last decades. NPs can be found in groundwater as natural colloids or anthropogenic NPs released from industrial processes. Moreover, engineered NPs can be injected on purpose into the subsurface for the remediation of contaminated aquifers. The aim of this work is to develop tools and methods to assess, optimize and predict the NP transport at field scale. The modelling tools MNMs and MNM3D were developed to deal with NP transport at the different scales. MNMs was developed for the quantitative analysis of laboratory-scale column tests and preliminary design of pilot injections in 1D radial geometries. MNMs is embedded in a user-friendly graphical interface to be easily applied by final users. MNM3D is a full 3D model for the simulation of NP transport at the field-scale. MNM3D represents the most important innovation of this study, extending for the first time the ionic strength and velocity dependent transport of NPs to 3D geometries and complex scenarios. MNM3D is currently being implemented in the Visual Modflow interface to make it easily available to practitioners and to promote its diffusion in the remediation field. MNM3D was successfully applied for the interpretation of column transport tests of ferrihydrite NPs under transients of ionic strength and for the simulation of the injection of Carbo-Iron® NPs in a 2D large scale experiment. The good results obtained suggest that MNM3D may be a useful tool to simulate the long term fate of NPs in fieldscale conditions and to support the design of a nanoremediation, thus promoting the definitive establishment of this technology. Experimental tests were carried out to study the transport of humic acids-coated goethite NPs under transient geochemical conditions and to optimize their delivery into the subsurface. NP stability and mobility were found to be strongly dependent on the dose of calcium in the suspension. The concentration of the slurry was the key parameter controlling the NP delivery: high concentrations provide additional stability and mobility to the slurry. This result was surprisingly in contrast to the common practice of keeping low the concentration to reduce the NP aggregation phenomena. These findings were also used to develop an injection strategy to control the delivery of goethite NPs in sand columns. A reactive zone can be created in the desired portion of the column by tuning the NP deposition in space and time. If up-scaled, this method can be used to control the delivery of NPs in field applications, improving the effectiveness of the remediation and allowing a more rational use of the slurry, with a consequent reduction of the overall costs of the technology. This protocol is part of a more general patent application about methods for a controlled deposition and immobilization of colloids in porous media. Finally, an integrated experimental-modelling approach was presented to foresee the NP behavior at the field scale by characterizing the NP transport at the laboratory scale. Targeted laboratory experiments are performed to identify the main driving forces influencing the NP mobility and to derive site specific transport parameters by modelling interpretation of the results with MNMs. The results are then up-scaled to foresee the NP transport at larger scales using MNM3D. The approach allows to get a reliable estimation of several operative parameters (e.g. NP distribution, radius of influence, number of wells, etc.) and to easily span a wide range of conditions requiring only a limited number of laboratory and pilot tests. In this work, the combined experimental and modelling approach was applied to the design of an iron oxide-based nanoremediation and for the prediction of the long term fate of graphene oxides NPs. This work was co-founded by the European research projects NanoRem (FP7, G.A. 309517) and Reground (H2020, G.A. 641768).