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Transport property prediction of fatty acid methyl esters (FAMEs) is essential to its utilisation as biodiesel and biolubricant which can work under high-pressure conditions. Equilibrium molecular simulation is performed to study the viscosity, diffusivity, density and molecular structure dynamics at conditions up to 300 MPa. Among the transport properties, convergence of the viscosity needs a sufficiently large number of independent replications of the simulation. The system size effect on diffusion coefficient should be taken into consideration in fitting the Stokes-Einstein relation. The capability of three different force fields on predicting transport properties is evaluated in terms of the united-atom molecular model and all-atom molecular model. The solidification of FAMEs under high pressure occurs with parallel molecular alignment. The spatial inhomogeneity results in the breakdown of Stokes-Einstein relation. A hybrid effective hydrodynamic radius is established on the linear relation between experimental viscosity and diffusion coefficient in molecular simulation. This provides a predictive method to estimate viscosity from molecular diffusion coefficient over a broad range of conditions provided that Stokes-Einstein relation applies. Peer Reviewed

A simple, efficient and general approach for all-visible-light switching of photochromic diarylethenes is developed through triplet sensitization from CdS nanocrystals, which has high potential for all-visible-light activated optoelectronics.

Conventionally, high-pressure water-based fluids have been injected for hydraulic stimulation of unconventional petroleum resources such as tight gas reservoirs. Apart from improving productivity, water-based frac-fluids have caused environmental and technical issues. As a result, much of the interest has shifted towards alternative frac-fluids. In this regard, n-heptane, as an alternative frac-fluid, is proposed. It necessitates the development of a multi-phase and multi-component (MM) numerical simulator for hydraulic fracturing. Therefore fracture, MM fluid flow, and proppant transport models are implemented in a thermo-hydro-mechanical (THM) coupled FLAC3D-TMVOCMP framework. After verification, the model is applied to a real field case study for optimization of wellbore x in a tight gas reservoir using n-heptane as the frac-fluid. Sensitivity analysis is carried out to investigate the effect of important parameters, such as fluid viscosity, injection rate, reservoir permeability etc., on fracture geometry with the proposed fluid. The quicker fracture closure and flowback of n-heptane compared to water-based fluid is advantageous for better proppant placement, especially in the upper half of the fracture and the early start of natural gas production in tight reservoirs. Finally, fracture designs with a minimum dimensionless conductivity of 30 are proposed.

Abstract Recent controversy regarding the existence of massive ( log ( M * / M ⊙ ) ≳ 11 ) galaxies at z > 6 poses a challenge for galaxy formation theories. Hence, it is of critical importance to understand the effects of SED fitting methods on stellar mass estimates of Epoch of Reionization galaxies. In this work, we perform a case study on the AGN host galaxy candidate COS-87259, with spectroscopic redshift z spec = 6.853, that is claimed to have an extremely high stellar mass of log ( M * / M ⊙ ) ∼ 11.2 . We test a suite of different SED fitting algorithms and stellar population models on our independently measured photometry in 17 broad bands for this source. Between five different code setups, the stellar mass estimates for COS-87259 span log ( M * / M ⊙ ) = 10.24 –11.00, while the reduced χ 2 values of the fits are all close to unity within Δ χ ν 2 = 1.2 , such that the quality of the SED fits is basically indistinguishable. Only when we adopt a nonparametric star formation history model within Prospector do we retrieve a stellar mass exceeding log ( M * / M ⊙ ) = 11 . Although the derived stellar masses change when using previously reported photometry for this source, the nonparametric SED-fitting method always yields the highest values. As these models are becoming increasingly popular for James Webb Space Telescope high-redshift science, we stress the absolute importance of testing various SED fitting routines particularly on apparently very massive galaxies at such high redshifts.

The Nepalese Mustang District is subject to profound environmental change. In recent decades, rising temperatures have been apparent, accompanied by increasing precipitation variability and a reduction in glacier extent. In a semi-arid climate, this reduces water availability and threatens irrigation-based subsidence agriculture. In addition, the region is experiencing rapid socio-economic change due to a new road connecting the former periphery to new markets downstream. This enables a higher market orientation for agricultural products and improved accessibility for tourists. In recent decades, these changes have triggered severe transformations in the local land-use systems and settlements, which are investigated in this study. Detailed on-site re-mappings of the settlements of Marpha and Kagbeni were performed based on historical maps from the early 1990s. Additionally, land-use patterns and functionality of buildings in the district capital of Jomsom and in the settlement Ranipauwa/Muktinath were mapped. For all settlements, a profound increase in cash crop (apple) cultivation can be observed since the 1990s. Recently, new cultivation practices such as intercropping have been extensively introduced as an adaptation strategy to climate extremes. Demand for different crops from the new markets downstream is causing a significant decline in local, well-established cultivation of traditional crops such as buckwheat. This corroborates with an increasing demand for freshwater for the enhanced vegetable cultivation used for inter-cropping. Simultaneously, the freshwater demands from the tourism sector are steadily increasing. In a region where water quality is deteriorating and springs are already drying up due to climate change, this will probably lead to further challenges regarding the allocation of water in the future.

The accessibility of pores to methane has been investigated in Devonian New Albany Shale Formation early-mature (Ro = 0.50%) to post-mature (Ro = 1.40%) samples. A Marcellus Shale Formation sample was included to expand the maturation range to Ro 2.50%. These are organic matter-rich rocks with total organic carbon (TOC) values of 3.4 to 14.4% and porosity values of 2.19 to 6.88%. Contrast matching small-angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) techniques were used to generate porosity-related data before and after pressure cycling under hydrostatic (in a vacuum and at 500 bar of deuterated methane) and uniaxial stress (0 to ca. 350 bar) conditions. Our results showed that the accessible porosity was small for the samples studied, ranging from zero to 2.9%. No correlation between the accessible porosity and TOC or mineralogical composition was revealed, and the most likely explanation for porosity variation was related to the thermal transformation of organic matter and hydrocarbon generation. Pressure caused improvements in accessible porosity for most samples, except the oil window sample (Ro = 0.84%). Our data show that densification of methane occurs in nanopores, generally starting at diameters smaller than 20 nm, and that the distribution of methane density is affected by pressure cycling.

Agriculture has radically changed the global nitrogen (N) cycle and is heavily dependent on synthetic N-fertiliser. However, the N-use efficiency of synthetic fertilisers is often only 50% with N-losses from crop systems polluting the biosphere, hydrosphere and atmosphere. To address the large carbon and energy footprint of N-fertiliser synthesis and curb N-pollution, new technologies are required to deliver enhanced energy efficiency, decarbonisation and a circular nutrient economy. Algae fertilisers (AF) are an alternative to synthetic N-fertiliser (SF). Here microalgae were used as biofertiliser for spinach production. AF production was evaluated using life-cycle analyses. Over 4 weeks, AF released 63.5% of N as bioavailable ammonium and nitrate, and 25% of phosphorous (P) as phosphate to the growth substrate; SF released 100% N and 20% P. To maximise crop N-use and minimise N-leaching, we explored AF and SF dose-response-curves with spinach in glasshouse conditions. AF-grown spinach produced 36% less biomass than SF-grown plants due to AF's slower and linear N-release; SF exhibited 5-times higher N-leaching than AF. Optimised AF:SF blends yielded greater synchrony between N-release and crop-uptake, boosting crop yields and minimising N-loss. Additional benefits of AF included greener leaves, lower leaf nitrate concentration, and higher microbial diversity and water holding capacity of the growth substrate. An integrated techno-economic and life-cycle-analysis of scaled-up microalgae systems (+/- wastewater) normalised to the application dose showed that replacing the most effective SF-dose with AF lowered the annual carbon footprint of fertiliser production from 3.644 kg CO2 m-2 (C-producing) to -6.039 kg CO2 m-2 (C-assimilation). N-loss from growth substrate was lowered by 54%. Embodied energy for AF:SF blends could be reduced by 29% when cultivating microalgae on wastewater. Conclusions: (i) microalgae offer a sustainable alternative to synthetic N-fertiliser for spinach production and potentially other crop systems, (ii) microalgae biofertilisers support the circular-nutrient-economy and several UN-Sustainable-Development-Goals.

The influence of the Na content and incorporation procedure into Cu2ZnGe(S,Se)4 (CZGSSe) thin films and solar cells is investigated. The effects of the presence/absence of Se during the deposition of a 15 nm thick NaF layer before and/or after the Cu2ZnGeSe4 (CZGSe) co-evaporation, are compared. Both the Na content, and Na-supply method significantly influence the incorporation of S into the CZGSe lattice and its distribution in the absorber. A [S]/([S] + [Se])-gradient throughout the CZGSSe layers is observed for all the samples and correlated with effects induced by the Na incorporation procedure. For instance, the evaporation of Se together with NaF leads to an increased S concentration in the surface-region of the CZGSSe layer and a modified surface morphology. CZGSSe-based solar cells with band gap energies of about 2 eV are obtained, regardless of the NaF addition method used, while the absence of the NaF layer reduces the S incorporation and the Eg. However, the evaporation of Se together with NaF results in higher Eg and open circuit voltage VOC, probably related to a higher S accumulation near the surface, demonstrating the importance of the [S]/([S] + [Se]) distribution. CZGSSe-based photovoltaic devices with efficiency of 3.2 % and Eg of 2 eV are obtained This work was supported by Spanish Ministry of Science, Innovation and Universities Project (WINCOST: ENE2016-80788-C5-2-R), CELL2-WIN: PID2019-104372RB-C32) and European Project INFINITE-CELL (H2020-MSCA-RISE-2017-777968). The authors acknowledge the service from the MiNa Laboratory at IMN-CSIC, and funding from CM (project S2018/ NMT-4291 TEC2SPACE), MINECO (project CSIC13-4E-1794) and European Union (FEDER, FSE)