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An isothermal compressible single-phase fluid flow through a non-homogeneous granular body composed of densely packed overlapping spheres imitating rock under high pressure was numerically studied using two different approaches. The first approach called the full 3D CFD model used the finite volume method (FVM) to solve the Reynolds-averaged Navier–Stokes equations using Reynolds stress model (BSL) in the continuous domain between the granulates. The model was verified, based on experimental and numerical results from the literature. The second approach was a simplified coupled DEM-CFD model based on a fluid flow network. The main aim of the work was to develop a validation procedure for simplified coupled DEM-CFD models due to the lack of experimental data for fluid flow characteristics in densely packed granules under extremely high-pressure conditions. First, a series of numerical simulations were performed for the fluid domain with the full 3D CFD model. The results of those simulations were next used to validate the 2D numerical results of the simplified coupled DEM-CFD model with respect to velocities, pressures, densities and flow rates. Almost the same pressure and density distributions and mass flow rates were obtained in both approaches. However, the fluid velocity was different due to the different fluid volumes in both fluid domains. The current simulation results constitute a reliable benchmark for validating other coupled 2D/3D DEM-CFD models that use a fluid flow network approach. [ABSTRACT FROM AUTHOR]

The lack of animal models for some human diseases precludes our understanding of disease mechanisms and our ability to test prospective therapies in vivo. Generation of kidney organoids from Tuberous Sclerosis Complex (TSC) patient-derived-hiPSCs allows us to recapitulate a rare kidney tumor called angiomyolipoma (AML). Organoids derived from TSC2−/− hiPSCs but not from isogenic TSC2+/− or TSC2+/+ hiPSCs share a common transcriptional signature and a myomelanocytic cell phenotype with kidney AMLs, and develop epithelial cysts, replicating two major TSC-associated kidney lesions driven by genetic mechanisms that cannot be consistently recapitulated with transgenic mice. Transplantation of multiple TSC2−/− renal organoids into the kidneys of immunodeficient rats allows us to model AML in vivo for the study of tumor mechanisms, and to test the efficacy of rapamycin-loaded nanoparticles as an approach to rapidly ablate AMLs. Collectively, our experimental approaches represent an innovative and scalable tissue-bioengineering strategy for modeling rare kidney disease in vivo. The lack of animal models for some human diseases precludes our understanding of disease mechanisms and our ability to test new therapies in vivo. Here the authors present a tissue bioengineering strategy for the study of a rare kidney tumor called angiomyolipoma, in vitro and in vivo, using patient-derived hiPSCs. [ABSTRACT FROM AUTHOR]

We study the CR-hypersurfaces of a conformal Kenmotsu space form with a ξ-parallel normal Jacobi operator. We also present an illustrative example of a three-dimensional conformal Kenmotsu manifold that is not Kenmotsu. [ABSTRACT FROM AUTHOR]

New chloroantimonite glasses were obtained in the SbO - PbCl -AgCl ternary system. Their thermal, optical, and mechanical properties are studied. The concentration of silver chloride increases at the expense of antimony oxide accordingtothe following composition rules: (80- x)SbO -20PbCl - xAgCl and (70- x)SbO -30PbCl - xAgCl. Depending on the AgCl content, Vickers microhardness varied between 110 MPa and 140 MPa. The elastic moduli were measured by ultrasonic velocity. The optical transmission range extended from 400 nm in the visible spectrum to 7 μm in the infrared spectrum. The refractive index was close to 2. The glass transition temperature measured by the DSC ranged from 250 to 290°C. It is shown that the glass transition temperature decreases as AgCl substitutes for SbO and a more stable system was with 20% PbCl in the (80- x)SbO -20PbCl - xAgCl. [ABSTRACT FROM AUTHOR]

The evolution of strength of silica optical fibers aged in cetyltrimethylammonium chloride solution (CTAC) is investigated. The mechanical behavior of silica-coated and naked fibers is studied in contact with CTAC solutions of different concentrations. The results of our analyses prove that the immersion in CTAC drastically decreases the strength of fibers, especially near the critical micelle concentration (CMC). Beyond the CMC, a small increase in the fiber strength is detected and discussed. Based on the analysis of the aged surface morphology of the fibers obtained from scanning electron microscopy, the extent of damage to the fiber core and polymer coatings is obtained. [ABSTRACT FROM AUTHOR]

For automotive applications, the mechanical behaviour of the contact area under vibration is one of the key factors for connector reliability. Such vibrations on the bulk contact device are typically in the range of 10-2,000 Hz and result in displacements of only a few microns at the contact interface. In the present study, a bench test has been developed to control motions down to 1 $$\upmu $$m. The objective is to determine the minimum amplitude for fretting-corrosion degradation based on the evolution of contact resistance and to study the effects of the material, the contact force, the coating, for these low displacement amplitudes. To obtain the limit of the appearance of fretting, a sub-micrometer incrementing displacement amplitude methodology was applied on a high stiffness bench test including a double piezoelectric actuator. It was found that the fretting degradation starts to occur from 2 to 6 $$\upmu $$m when the contact force is from 0.5 to 2.5 N with a tin-coated terminal. Moreover, pure copper, tin and nickel have similar amplitude fretting limits while noble metals confirm the absence of fretting up to 10 $$\upmu $$m amplitude and for a large number of operations (10 $$^{6 }$$ cycles). Best fitting of the obtained minimum fretting amplitude data to the Mindlin equation is discussed and improved by a correction factor. [ABSTRACT FROM AUTHOR]

GVHD remains the most significant complication of hematopoietic SCT, despite advances in HLA matching and the identification of risk various factors. To account for the variation in the incidence and severity of this disease, many genetic association studies have been performed in order to explore the role of immunoregulatory gene polymorphisms. These genes include those that encode cytokines, chemokines, and costimulatory molecules. Polymorphisms in other classes of genes such as those involved in drug metabolism, protein folding, and DNA replication have also been studied. In this review, we address the current knowledge of the role of genetic polymorphisms in GVHD. We also discuss the potential pitfalls inherent in genetic association testing and alternative strategies to address these problems. [ABSTRACT FROM AUTHOR]

The increased optical fiber development for a variety of physical and chemical measurements using smart structures and sensors leads to investigate the mechanical and chemical reliability of standard commercial acrylate polymer coated fibers. Multimode optical fiber was subjected to aggressive chemical reagents in gaseous and liquid phase, such as acetylene, ammonia, dimethyl-sulfoxide for different durations after prior vacuum exposure. Tensile testing results were treated using Weibull statistic. A comparison of mean failure strengths of aged fibers for similar exposure duration has revealed the highest sensitivity to acetylene and dimethyl-sulfoxide reagents. Based on analysis of aged fiber surface morphology obtained from Scanning Electron Microscopy, we can deduce the damage extent and the consequence on the structure of the fiber in contact with these harsh environments. [ABSTRACT FROM AUTHOR]

Besides signal transmission for telecommunications, fibers are used in an increasing number of devices. A number of applications relate to devices exposed to severe wet environment (hot water, chemical attacks...). It is the case for the sensors used in nuclear plants, high energy physics or plasmas devices. However, reliability issues must be addressed for optical fiber sensors operating under severe conditions such as harsh chemical solutions. The purpose of this work is to study the mechanical behavior and aging of fibers exposed to hot water action, to hydrofluoric acid vapours (HF) and to tetramethoxysilane (TMOS) for different durations. Dynamic fatigue tests were implemented using a two-point bending testing device or tensile test set-up. Standard fibers tested immediately after exposure show a broader distribution of fiber strength accompanied by the drastic decrease of the failure stress. In some particular cases, the gain compared to as received fibers can be positive. Polymer reacts with different wet environments, which induces viscosity changes. This is consistent with SEM observations. [ABSTRACT FROM AUTHOR]

Patients with coronavirus disease 2019 (COVID-19) are reported to have a greater prevalence of hyperglycaemia. Cytokine release as a consequence of severe acute respiratory syndrome coronavirus 2 infection may precipitate the onset of metabolic alterations by affecting glucose homeostasis. Here we describe abnormalities in glycometabolic control, insulin resistance and beta cell function in patients with COVID-19 without any pre-existing history or diagnosis of diabetes, and document glycaemic abnormalities in recovered patients 2 months after onset of disease. In a cohort of 551 patients hospitalized for COVID-19 in Italy, we found that 46% of patients were hyperglycaemic, whereas 27% were normoglycaemic. Using clinical assays and continuous glucose monitoring in a subset of patients, we detected altered glycometabolic control, with insulin resistance and an abnormal cytokine profile, even in normoglycaemic patients. Glycaemic abnormalities can be detected for at least 2 months in patients who recovered from COVID-19. Our data demonstrate that COVID-19 is associated with aberrant glycometabolic control, which can persist even after recovery, suggesting that further investigation of metabolic abnormalities in the context of long COVID is warranted.