LCPOM: Precise Reconstruction of Polarized Optical Microscopy Images of Liquid Crystals

When viewed with a cross-polarized optical microscope (POM), liquid crystals display interference colors and complex patterns that depend on the material's microscopic orientation. That orientation can be manipulated by application of external fields, which provides the basis for applications in optical display and sensing technologies. The color patterns themselves have a high information content. Traditionally, however, calculations of the optical appearance of liquid crystals have been performed by assuming that a single-wavelength light source is employed, and reported in a monochromatic scale. In this work, the original Jones matrix method is extended to calculate the colored images that arise when a liquid crystal is exposed to a multi-wavelength source. By accounting for the material properties, the visible light spectrum and the CIE color matching functions, we demonstrate that the proposed approach produces colored POM images that are in quantitative agreement with experimental data. Results are presented for a variety of systems, including radial, bipolar, and cholesteric droplets, where results of simulations are compared to experimental microscopy images. The effects of droplet size, topological defect structure, and droplet orientation are examined systematically. The technique introduced here generates images that can be directly compared to experiments, thereby facilitating machine learning efforts aimed at interpreting LC microscopy images, and paving the way for the inverse design of materials capable of producing specific internal microstructures in response to external stimuli.Comment: 12 pages, 5 figures (main text). 6 pages, 6 figures (appendices

Reversible Non-Volatile Electronic Switching in a Near Room Temperature van der Waals Ferromagnet

The ability to reversibly toggle between two distinct states in a non-volatile method is important for information storage applications. Such devices have been realized for phase-change materials, which utilizes local heating methods to toggle between a crystalline and an amorphous state with distinct electrical properties. To expand such kind of switching between two topologically distinct phases requires non-volatile switching between two crystalline phases with distinct symmetries. Here we report the observation of reversible and non-volatile switching between two stable and closely-related crystal structures with remarkably distinct electronic structures in the near room temperature van der Waals ferromagnet Fe$_{5-\delta}$GeTe$_2$. From a combination of characterization techniques we show that the switching is enabled by the ordering and disordering of an Fe site vacancy that results in distinct crystalline symmetries of the two phases that can be controlled by a thermal annealing and quenching method. Furthermore, from symmetry analysis as well as first principle calculations, we provide understanding of the key distinction in the observed electronic structures of the two phases: topological nodal lines compatible with the preserved global inversion symmetry in the site-disordered phase, and flat bands resulting from quantum destructive interference on a bipartite crystaline lattice formed by the presence of the site order as well as the lifting of the topological degeneracy due to the broken inversion symmetry in the site-ordered phase. Our work not only reveals a rich variety of quantum phases emergent in the metallic van der Waals ferromagnets due to the presence of site ordering, but also demonstrates the potential of these highly tunable two-dimensional magnets for memory and spintronics applications

Credit Risk Diffusion in Supply Chain Finance: A Complex Networks Perspective

The diffusion of credit risk in a supply chain finance network can cause serious consequences. Using the “1 + M + N„ complex network model with BA scale-free characteristics, this paper studies the credit risk diffusion in a supply chain finance network, where the credit risk diffusion process is simulated by the SIS epidemic model. We examine the impacts of various key factors, including the general financing ratio, cure time, network structure, and network scale on the credit risk diffusion process. It is found that credit risk diffusion rarely occurs in a network with a low average degree. When the average degree of the network increases, the occurrence of the credit risk diffusion becomes more frequent. Besides, the degree of the initially infected nodes with credit risk does not affect the density of the infected nodes in the steady state, while a higher degree of the cure nodes helps restrain the diffusion of credit risk in the supply chain finance network. Finally, the simulation result based on the supply chain finance network with a core node indicates that the diffusion of the credit risk diffusion in sparse supply chain finance networks with low average degrees is unstable. The results provide better understandings on the credit risk diffusion in supply chain finance networks

Development of a model for the optimization of the main factors influencing a 162kW wheeled tractor driver’s whole body vibration

The vibration tests were carried out using a 162kW wheeled tractor to evaluate the Whole-body vibration while the tractor working in the field, driving on concrete road and in-parking state. The tractor ride comfort was analyzed using the joint weighted acceleration of seat surface vibration from 1 to 80 Hz as the evaluation indicator, according to ISO2631 standard suggestions. During field work, the combined acceleration of the driver’s whole body vibration is 1.39, and the subjective feeling is extremely uncomfortable. Based on the multi-body dynamics analysis software, a tractor dynamics simulation model including the seat, cab mounts, chassis, tyre and road coupling system was established. By changing the model parameters, the influence of the tractor driver’s whole body vibration under the condition of the artificial test track was further analyzed. The analysis shows that the factors that have a greater impact on the driver’s whole body vibration when driving on the artificial runway are the vertical stiffness of the tyre, the vertical stiffness of the seat suspension, and the damping coefficient of the tyre

Solvation effect of [BMIM]Cl/AlCl3 ionic liquid electrolyte

Four kinds of solvents, methylene chloride (CH2Cl2), toluene (TOL), ethyl acetate (EtoAc), and dimethyl carbonate (DMC), were added into the 1-butyl-3-methylimidazolium chloroaluminate ionic liquid ([BMIM]Cl/AlCl3 IL) to improve the property of the IL-based electrolyte for aluminum (Al) electrolysis. Solvation effects of these solvents on the physical properties, electrochemical properties, and electroactive ion of the [BMIM]Cl/AlCl3 IL-based electrolyte were investigated. It was found that the viscosity of the IL electrolyte decreased after adding CH2Cl2 or TOL, and the conductivity increased while the change of the conductivity and the viscosity moved in the opposite direction with the addition of EtoAc or DMC. The UV-Vis spectra showed that the electroactive Al ion continued existence after adding CH2Cl2 or TOL, but there was solvation effect between TOL and BMIM+. On the other hand, both EtoAc and DMC had solvation effects with electroactive Al ion and BMIM+. The results illustrated that solvation effect was the key effect on the reduction of Al on the cathode, and further influenced the morphology of the Al deposits. In addition, the concentration polarization reduced and the efficiency of electrolysis improved after adding CH2Cl2 or TOL. Furthermore, bright Al coatings were obtained finally by adding CH2Cl2 into [BMIM]Cl/AlCl3 IL electrolyte (when the mole ratio of CH2Cl2 is around 66.7 similar to 75%)

Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy

Optimization of the depressurization pathways plays a crucial role in avoiding potential geohazards while increasing hydrate production efficiency. In this study, methane hydrate was formed in a flexible plastic vessel and then gas production processes were conducted at constant confining pressure and constant confining temperature. The CMG-STARS simulator was applied to match the experimental gas production behavior and to derive the hydrate intrinsic dissociation constant. Secondly, fluid production behavior, pressure-temperature (P‐T) responses, and hydrate saturation evolution behaviors under different depressurization pathways were analyzed. The results show that integrated gas-water ratio (IGWR) decreases linearly with the increase in depressurizing magnitude in each step, while it rises logarithmically with the increase in the number of steps. Under the same initial average hydrate saturation and the same total pressure-drop magnitude, a slow and multistage depressurization strategy would help to increase the IGWR and avoid severe temperature drop. The pore pressure rebounds logarithmically once the gas production is suspended, and would decrease to the regular level instantaneously once the shut-in operation is ended. We speculate that the shut-in operation could barely affect the IGWR and formation P‐T response in the long-term level

The Beneficial Effects of Two Polysaccharide Fractions from <i>Sargassum fusiform</i> against Diabetes Mellitus Accompanied by Dyslipidemia in Rats and Their Underlying Mechanisms

The current study aimed to assess the anti-diabetic effects and potential mechanisms of two Sargassum fusiform polysaccharide fractions (SFPs, named SFP-1 and SFP-2). The carbohydrate-loading experiment revealed that SFP-2 could control postprandial hyperglycemia by inhibiting the activity of digestive enzymes in rats. The analysis of diabetic symptoms and serum profiles indicated that SFPs could mitigate diabetes accompanied by dyslipidemia, and SFP-2 showed better regulatory effects on body weight, food intake and the levels of total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C) and free fatty acid (FFA) in diabetic rats. Intestinal bacterial analysis showed that SFP treatment could reshape the gut flora of diabetic rats, and SFP-2 possessed a greater regulatory effect on the growth of Lactobacillus and Blautia than SFP-1. RT-qPCR analysis revealed that SFPs could regulate the genes involved in the absorption and utilization of blood glucose, hepatic glucose production and lipid metabolism, and the effects of SFP-2 on the relative expressions of Protein kinase B (Akt), Glucose-6-phosphatase (G-6-Pase), Glucose transporter 2 (GLUT2), AMP-activated protein kinase-α (AMPKα), Peroxisome proliferator-activated receptor γ (PPARγ) and Cholesterol 7-alpha hydroxylase (CYP7A1) were greater than SFP-1. All above results indicated that SFPs could be exploited as functional foods or pharmaceutical supplements for the treatment of diabetes and its complications

Asiatic Acid Attenuates Myocardial Ischemia/Reperfusion Injury via Akt/GSK-3β/HIF-1α Signaling in Rat H9c2 Cardiomyocytes

Myocardial ischemic/reperfusion injury results from severe impairment of coronary blood supply and leads to irreversible cell death, with limited therapeutic possibilities. Asiatic acid is a pentacyclic triterpenoid derived from the tropical medicinal plant Centella asiatica and serves a variety of bioactivities. In this study, we determined the effect of asiatic acid on myocardial ischemia/reperfusion injury and investigated the underlying mechanisms, using an in vitro rat H9c2 cardiomyocytes model of oxygen-glucose deprivation/reoxygenation (OGD/R) injury. Results showed that pre-treatment with asiatic acid significantly augmented cell viability and prevented lactate dehydrogenase (LDH) release in a concentration-dependent manner after OGD/R exposure. Asiatic acid at 10 μM effectively inhibited apoptotic cell death, suppressed the activities of caspase-3 and caspase-9, and reversed Bax/Bcl-2 ratio in hypoxic H9c2 cells. In addition, asiatic acid improved mitochondrial function, as evidenced by reduced reactive oxygen species (ROS) accumulation, enhanced mitochondrial membrane potential and decreased intracellular calcium concentration. Using Western blot assay, we found that asiatic acid promoted the phosphorylation of Akt and subsequent inactivation of glycogen synthase kinase-3β (GSK-3β), and induced the expression of hypoxia-inducible factor 1α (HIF-1α) after OGD/R. The cardioprotective effects of asiatic acid were attenuated by the Akt or HIF-1α inhibitor. Taken together, these data suggested that asiatic acid exerted protective effects against OGD/R-induced apoptosis in cardiomyocytes, at least partly via the Akt/GSK-3β/HIF-1α pathway