Proteomic Analysis of Rat Hypothalamus Revealed the Role of Ubiquitin–Proteasome System in the Genesis of DR or DIO

Obesity has become a global epidemic, contributing to the increasing burdens of cardiovascular disease and type 2 diabetes. However, the precise molecular mechanisms of obesity remain poorly elucidated. The hypothalamus plays a major part in regulating energy homeostasis by integrating all kinds of nutritional signals. This study investigated the hypothalamus protein profile in diet-induced obese (DIO) and diet-resistant (DR) rats using two dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF–MS analysis. Twenty-two proteins were identified in the hypothalamus of DIO or DR rats. These include metabolic enzymes, antioxidant proteins, proteasome related proteins, and signaling proteins, some of which are related to AMP-activated protein kinase (AMPK) signaling or mitochondrial respiration. Among these proteins, in comparison with the normal-diet group, Ubiquitin was significantly decreased in DR rats but not changed in DIO rats, while Ubiquitin carboxyl-terminal esterase L1 (UCHL-1) was decreased in DIO rats but not changed in DR rats. The expression level of Ubiquitin and UCHL-1 were further validated using Western blot analysis. Our study reveals that Ubiquitin and UCHL-1 are obesity-related factors in the hypothalamus that may play an important role in the genesis of DR or DIO by interfering with the integrated signaling network that control energy balance and feeding

Seismic stability of coal tailings dams with spatially variable and liquefiable coal tailings using pore pressure plasticity models

Failure of tailings dams can result in significant spill, loss of human lives, and damages to the environment and infrastructure. Cyclic loadings such as earthquakes and blasting are among the main threats to the stability of tailings dams. Seismic stability analyses of tailings dams are further challenged by the uncertainty and variability of tailings properties. In this paper, the influence of input motion characteristics and spatial variability in coal tailings (CT) properties on the seismic stability of a typical upstream-construction CT dam is investigated. Among the input motion characteristics, peak ground acceleration (PGA), equivalent number of cycles (ENC), and frequency content are the focus of this study. First, the applicability of two advanced constitutive plasticity models, PM4Sand and PM4Silt, in simulating the cyclic behavior of CT is evaluated and a suitable model is selected. The undrained shear strength of CT is modeled as a spatially correlated Gaussian random field. Six input motions — one blast and five earthquakes — are selected for the dynamic analyses. The dynamic analyses are conducted in co-seismic and then post-seismic stages. The seismic stability of the CT dam with uniform properties (i.e. uniform models) is compared to the stochastic models under the selected input motions. Post-seismic analysis was found critical for the stochastic models. This study highlights the importance of stochastic modeling and the consideration of spatial variability in seismic stability analysis of CT dams

Effect of Light Biocementation on the Liquefaction Triggering and Post-Triggering Behavior of Loose Sands

Microbially induced calcite precipitation (MICP) is an environmentally conscious ground-improvement method that can enhance the engineering properties of granular soils through the precipitation of calcium carbonate (CaCO3) on soil particle surfaces and contacts. Although numerous studies have shown the ability of biocementation to improve the liquefaction resistance of loose sands, the effects of light cementation levels on undrained cyclic behaviors have remained relatively unexplored. A series of undrained monotonic and cyclic direct simple shear tests were performed to examine the effect of light biocementation (ΔVs<100 m/s and CaCO3 contents <0.9%) on the liquefaction triggering and post-triggering behavior of loose Ottawa F-65 sand subjected to varying loading magnitudes [cyclic stress ratio (CSR)=0.1 to 0.3]. Results suggest that the presence of light biocementation can significantly improve the liquefaction triggering resistance of loose sands, with log-linear increases in the number of cycles required to trigger liquefaction, which consistently correlated with cementation-induced Vs increases. Despite these remarkable pretriggering improvements, almost no improvements were observed in post-triggering strain accumulation and postcyclic reconsolidation behaviors, with Vs measurements indicating that small-strain improvements were largely erased following shearing events

Development and Evaluation of Preconditioning Protocols for Sand Specimens in Constant- Volume Cyclic Direct Simple Shear Tests

Textured platens are often used to improve the transfer of shear stresses from the platens to the soil specimen during direct simple shear (DSS) tests. However, constant-volume DSS tests when textured platens are used can be affected by inadequate engagement of the soil at the platen-soil interface, leading to large reductions in the vertical stress at the start of shearing. The application of a preconditioning sequence involving small-strain drained cycles prior to constant-volume shearing can improve engagement at the platen-soil interface, but when excessively implemented, it can also have adverse effects on the measured soil behavior (e.g., strength, stiffness). A series of constant-volume cyclic DSS tests preceded by different preconditioning sequences was performed to evaluate the effect of preconditioning on the engagement of sand specimens at the platen-soil interface and the stress-strain response of these specimens. Results showed that textured platens that are properly engaged with sand specimens can reduce slippage at the platen-soil interface. This engagement can be achieved by applying a limited number of small-strain drained cycles at a low vertical stress while still obtaining representative soil behavior during the subsequent equivalent undrained constantvolume cyclic loading. Although the preconditioning protocol presented herein is specific to the testing equipment and materials considered, similar procedures may be adopted to develop preconditioning protocols for other soils, platens, and testing devices

Axisymmetric Simulations of Cone Penetration in Biocemented Sands

With the recent advances in the biogeotechnics field and specifically microbially induced calcite precipitation (MICP), cone penetration testing (CPT) has become a valuable tool to overcome the challenges associated with intact sampling of improved soils, evaluate the spatial extent and magnitude of the applied MICP treatment, and assess the consequential improvement of engineering properties. Although the CPT cone tip resistance (qc) can effectively monitor the improvement of densified clean sands, no relationship exists to estimate cementation and strength parameters in MICP-treated sands. This paper proposes a relationship between the apparent cohesion (c) stemming from the MICP-induced cementation bonds at particle contacts and the change in tip resistance (qc) in initially loose sands. To develop a broadly useful correlation, available experimental CPT data in biocemented soils were used to guide computation simulations using a direct axisymmetric model of cone penetration in biocemented sands. The CPT numerical model uses the finite-difference method with a rezoning algorithm for large-deformation problems along with the Mohr-Coulomb constitutive model. The biocemented sand was characterized by Mohr-Coulomb strength parameters and an elastic shear modulus informed by shear-wave velocity measurements (Vs). The correlation parameters of interest were identified (c, qc, and Vs), and results of the numerical simulations were validated against available experimental data. Once validated, the numerical simulations were extended to different initial conditions, and the trends between parameters of interest were analyzed and interpreted. Results from the simulations are consistent with experimental data and show an increase in the cone tip resistance as the cementation level increases. The cementation level is modeled through apparent cohesion and the shear stiffness model parameters, which both increase as the cementation level increases. A linear relationship is proposed between the apparent cohesion and the change in cone tip resistance as a function of the confining stress

Axisymmetric Simulations of Cone Penetration in Biocemented Sands

With the recent advances in the biogeotechnics field and specifically microbially induced calcite precipitation (MICP), cone penetration testing (CPT) has become a valuable tool to overcome the challenges associated with intact sampling of improved soils, evaluate the spatial extent and magnitude of the applied MICP treatment, and assess the consequential improvement of engineering properties. Although the CPT cone tip resistance (qc role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eqcqc) can effectively monitor the improvement of densified clean sands, no relationship exists to estimate cementation and strength parameters in MICP-treated sands. This paper proposes a relationship between the apparent cohesion (c role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3ecc) stemming from the MICP-induced cementation bonds at particle contacts and the change in tip resistance Δqc role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eΔqcΔqc in initially loose sands. To develop a broadly useful correlation, available experimental CPT data in biocemented soils were used to guide computation simulations using a direct axisymmetric model of cone penetration in biocemented sands. The CPT numerical model uses the finite-difference method with a rezoning algorithm for large-deformation problems along with the Mohr-Coulomb constitutive model. The biocemented sand was characterized by Mohr-Coulomb strength parameters and an elastic shear modulus informed by shear-wave velocity measurements (Vs role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eVsVs). The correlation parameters of interest were identified (c role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3ecc, qc role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eqcqc, and Vs role= presentation style= box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eVsVs), and results of the numerical simulations were validated against available experimental data. Once validated, the numerical simulations were extended to different initial conditions, and the trends between parameters of interest were analyzed and interpreted. Results from the simulations are consistent with experimental data and show an increase in the cone tip resistance as the cementation level increases. The cementation level is modeled through apparent cohesion and the shear stiffness model parameters, which both increase as the cementation level increases. A linear relationship is proposed between the apparent cohesion and the change in cone tip resistance as a function of the confining stress

Implementation, Validation, and Application of PM4Sand Model in PLAXIS

This paper presents the implementation, validation, and application of the PM4Sand model (version 3) formulated by Boulanger and Ziotopoulou (2015) in the PLAXIS finite element code. The model can be used for modelling geotechnical earthquake engineering applications, especially in the case liquefaction is likely to occur. The PM4Sand model represents an improvement of the elasto-plastic, stress ratio controlled, bounding surface plasticity model for sands formulated by Dafalias and Manzari (2004). The two-dimensional version has been implemented in PLAXIS and compared to the original implementation by Boulanger and Ziotopoulou (2015). The original implementation has been used in explicit finite difference simulations which can be sensitive to the size of the returned stress increment, based on the chosen time step size and loading rate. Therefore, the user needs to evaluate the sensitivity of the solution with respect to the chosen time step sizes. On the contrary, in the finite element method used here, the default time step together with the sub-stepping used at the constitutive model level provide a robust solution independent of the size of the returned stress increment.Geo-engineerin