Effect of Structure on Petrophysical Properties of Porous Media

The objective of this project is to relate the microscopic structure of porous media to macroscopic properties, such as porosity, permeability, dispersion coefficient, and chemical reactivity. In the first part of this study, fluid flow in porous media is simulated by a lattice gas automaton model. The fluid velocity profiles and pressure drops around obstacles of known-shape are calculated. Heterogeneous permeability fields at a macroscopic and megascopic length scale are created by distributing scatterers within the fluid flow field. These scatterers act as obstacles to flow. The loss in momentum of the fluid is directly related to the permeability of the lattice gas model. It is shown that by varying the probability of occurrence of solid nodes, the permeability of the porous medium can be changed over several orders of magnitude. To simulate fluid flow in heterogeneous permeability fields, isotropic, anisotropic, random, and correlated permeability fields are generated. The lattice gas model developed here is used to obtain the effective permeability as well as the local fluid flow field. The method presented here can be used to simulate fluid flow in arbitrarily complex, heterogeneous porous media. The lattice gas automaton model is also applied to the problem of simulating dispersion and mixing in heterogeneous porous media. We demonstrate here that tracer concentration profiles and longitudinal dispersion coefficients can be computed for heterogeneous porous media It is shown that some basic petrographic measurements such as pore perimeter, pore size, and grain surface area can be made from thin sections that can be used to obtain an order of magnitude estimate of flow properties, such as permeability. The reactivity of rock with acid in an acidizing process depends on the geometrical arrangement of various minerals with respect to each other. A model is developed where the minerals are located in accordance with thin section images. Since the rate of reaction of each mineral is known, an erosion process is used to obtain the reactivity of the rock as a function of time. It is shown that this model provides substantially different results than a simple model that is based only on the mineral abundance in the rock matrix. This result can have a significant impact on currently used acidizing simulators.Petroleum and Geosystems Engineerin

Glutathione Modified Gold Nanoparticles for Sensitive Colorimetric Detection of Pb2+ Ions in Rainwater Polluted by Leaking Perovskite Solar Cells

In the past few years, the advent of lead halide perovskite solar cells (PSCs) has revolutionized the prospects of the third- generation photovoltaics and the reported power conversion efficiency (PCE) has been updated to 22%. Nevertheless, two main challenges, including the poisonous content of Pb and the vexing instability toward water, still lie between the lab-based PSCs technology and large scale commercialization. With this background, we first evaluated Pb2+ concentration from the rainwater samples polluted by three types of markets promising PSCs with inductively coupled plasma mass spectrometry measurements (ICP-MS) as a case study. The influence of possible conditions (pH value and exposure time) on the contents of Pb2+ from the three PSCs was systematically compared and discussed. Furthermore, an optimized glutathione functionalized gold nanoparticles (GSH-AuNPs) colorimetric sensing assay was used to determine Pb2+ leaking from PSCs for the first time. The Pb2+-induced aggregation of sensing assay could be monitored via both naked eye and UV-vis spectroscopy with a detection limit of 15 and 13 nM, which are all lower than the maximum level in drinking water permitted by WHO. The quantitative detection results were compared and in good agreement with that of ICP-MS. The results indicate that the content of Pb2+ from three PSCs are in the same order of magnitude under various conditions. By the use of the prepared GSH-AuNPs self-assembled sensing assay, the fast and on-site detection of Pb2+ from PSCs can be realized

Preparation of Activated Carbons from Waste External Thermal-Insulating Phenolic Foam Boards

Activated carbons (ACs) were prepared by steam physical activation or KOH chemical activation with the waste external thermal-insulating phenolic foam board as the raw material. The Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific area, pore-size distribution and iodine value were used to characterize the properties of ACs. AC-1(with the method of KOH chemical activation) has the iodine value of 2300mg/g, BET specific area of 1293 m2g-1, average pore-size of 2.4 nm, and mainly composed of micropore and relatively small mesopore. AC-2(with the method of steam physical activation) has the iodine value of 1665mg/g. Compared with AC-2, AC-1 had a pore-size distribution with more evenly and relative concentrated, it’s belonging to the high microporosity materials. Actually, chemical activation had more significant influence on destruction of the pore wall than physical activation

Genomic Features and Molecular Function of a Novel Stress-Tolerant Bacillus halotolerans Strain Isolated from an Extreme Environment

Simple Summary: The Qinghai–Tibet Plateau is known as the “third pole of the world”. Due to the extreme geographical location, Qinghai–Tibet Plateau has unique ecosystems characterized by oxygen deficiency, low temperature, high salinity and alkalinity. We carried out the current study to explore the excellent extremophilic Bacillus strains via potential stress resistance as well as biocontrol properties in the Qinghai–Tibet Plateau. We found a Bacillus halotolerans strain with a promising ability to withstand harsh environments and which also exhibits an optimistic biocontrol activity against plant pathogens. We revealed the whole genome sequencing and its taxonomic position and elucidated its molecular functions that were responsible for enhancing stress tolerance as well as suppressing plant pathogens at the genetic level. Lastly, we identified this strain harbored the specific genes associated with stresses resistance, biocontrol function, and can be used as a biological agent in the agriculture field.Due to its topographical position and climatic conditions, the Qinghai–Tibet Plateau possesses abundant microorganism resources. The extremophilic strain KKD1 isolated from Hoh Xil possesses strong stress tolerance, enabling it to propagate under high salinity (13%) and alkalinity (pH 10.0) conditions. In addition, KKD1 exhibits promising biocontrol activity against plant pathogens. To further explore these traits at the genomic level, we performed whole-genome sequencing and analysis. The taxonomic identification according to the average nucleotide identity based on BLAST revealed that KKD1 belongs to Bacillus halotolerans. Genetic screening of KKD1 revealed that its stress resistance mechanism depends on osmotic equilibrium, membrane transportation, and the regulation of ion balance under salt and alkaline stress. The expression of genes involved in these pathways was analyzed using real-time quantitative PCR. The presence of different gene clusters encoding antimicrobial secondary metabolites indicated the various pathways by which KKD1 suppresses phytopathogenic growth. Moreover, the lipopeptides surfactin and fengycin were identified as being significant antifungal components of KKD1. Through comparative genomics analysis, we noticed that KKD1 harbored specific genes involved in stress resistance and biocontrol, thus providing a new perspective on the genomic features of the extremophilic Bacillus species.Peer Reviewe

Engagement of vimentin intermediate filaments in hypotonic stress

International audienceIntermediate filaments (IFs) play a key role in the control of cell structure and morphology, cell mechano-responses, migration, proliferation, and apoptosis. However, the mechanisms regulating IFs organization in motile adhesive cells under certain physical/pathological conditions remain to be fully understood. In this study, we found hypo-osmotic-induced stress results in a dramatic but reversible rearrangement of the IF network. Vimentin and nestin IFs are partially depolymerized as they are redistributed throughout the cell cytoplasm after hypo-osmotic shock. This spreading of the IFs requires an intact microtubule network and the motor protein associated transportation. Both nocodazole treatment and depletion of kinesin-1 (KIF5B) block the hypo-osmotic shock-induced rearrangement of IFs showing that the dynamic behavior of IFs largely depends on microtubules and kinesin-dependent transport. Moreover, we show that cell survival rates are dramatically decreased in response to hypo-osmotic shock, which was more severe by vimentin IFs depletion, indicating its contribution to osmotic endurance. Collectively, these results reveal a critical role of vimentin IFs under hypotonic stress and provide evidence that IFs are important for the defense mechanisms during the osmotic challenge. K E Y W O R D S cytoplasmic redistribution, hypo-osmosis, intermediate filaments, osmotic stress, vimenti

Highly Stretchable and Transparent Ionic Conductor with Novel Hydrophobicity and Extreme-Temperature Tolerance

Highly stretchable and transparent ionic conducting materials have enabled new concepts of electronic devices denoted as iontronics, with a distinguishable working mechanism and performances from the conventional electronics. However, the existing ionic conducting materials can hardly bear the humidity and temperature change of our daily life, which has greatly hindered the development and real-world application of iontronics. Herein, we design an ion gel possessing unique traits of hydrophobicity, humidity insensitivity, wide working temperature range (exceeding 100°C, and the range covered our daily life temperature), high conductivity (10-3~10-5 S/cm), extensive stretchability, and high transparency, which is among the best-performing ionic conductors ever developed for flexible iontronics. Several ion gel-based iontronics have been demonstrated, including large-deformation sensors, electroluminescent devices, and ionic cables, which can serve for a long time under harsh conditions. The designed material opens new potential for the real-world application progress of iontronics