Yield Point Research Articles

Seismic Performance Research on a Graded-Yielding Metal Brace with Self-Centering Functions

With the aim of achieving a graded-protection braced frame structure and minimizing the excessive residual deformation of traditional metal dampers under intense seismic action, a graded-yield-type metal self-centering brace (SC-GYMB) is proposed. The brace is composed of X-shaped and U-shaped steel plates with different yield point displacements, which jointly dissipate energy. Additionally, it employs a composite disc spring as a self-centering element to provide restoring force for the brace. The brace’s basic structure and working mechanism are described, and the theoretical model for its restoring force is derived. The ABAQUS finite element software (ABAQUS 2021) is utilized to investigate the hysteretic performance of the SC-GYMB under low-cycle reciprocating load, while thoroughly discussing the influence of various model parameters on its key mechanical behavior. The results demonstrate a strong agreement between the theoretical restoring force model and the numerical simulation results. The hysteretic curves of the braces exhibit a distinct “flag” characteristic, indicating excellent energy dissipation capacity and self-centering performance. Moreover, these curves display a hierarchical yield behavior that satisfies the seismic performance requirements for different intensity earthquakes. The deformation mechanism of X-shaped steel sheets transitions from bending deformation during the initial loading stage to tensile deformation in the subsequent loading stage. Increasing the initial pre-compression force of the combined disc spring enhances the restoration performance of the brace. Augmenting the thickness of X-shaped or U-shaped steel sheets modifies the displacement and load at both the first and second yield points, thereby enhancing energy dissipation capacity and bearing capacity of the brace; however, it also leads to increased residual deformation.

Impact of high-intensity ultrasound on interfacial protein adsorption of non-dairy whipping cream: Whipping properties and foam stabilization model

In this paper, the competitive adsorption and practical application characteristics of ultrasound treatment on the oil-water interface in non-dairy whipping cream were explored. The results showed that ultrasound treatment promoted the competitive adsorption of casein, resulting in an increase of interfacial protein loading in the system by 4.82 mg/m2 and a decrease in oil droplet size by 0.20 μm. In addition, due to the increase of interfacial protein in the system, the partial coalescence of the fat globule of systems decreased, which led to a rapid collapse of the foam after 2 days of storage. Ultrasound weakened the strength of the gel network inside emulsions, which weakened the anti-deformation ability of emulsions. Although the LVR of the ultrasonically treated samples narrowed after churning, the G′ value increased. In addition, the stress yield point of the foams shifted to higher strains as the ultrasonic power increased, implying better resistance to deformation.

Multiaxial characterisation and nonlinear thermoviscoelastic isotropic and orthotropic constitutive models of ETFE membranes

Ethylene-tetra-fluoroethylene (ETFE) is a stiff and ductile polymer widely employed in cladding elements for roofs and façades, formed in pneumatic cushions or tensioned foils. The material’s high thermoviscoelastic effects require a comprehensive time and temperature-dependent multiaxial characterisation and accurate constitutive model to foster the design of lightweight ETFE tensioned construction and their standards. A multiaxial experimental campaign is performed to assess the material response in a wide range of temperatures, from −20°C to 60°C, strain rates, from 0.01%/s to 1%/s, and mechanical loading conditions typical of ETFE buildings. Uniaxial and biaxial bulge tests on circular and elliptical samples are carried out to assess constant strain rates, pressure rates and temperatures, unloading, cyclic, creep and relaxation conditions until the material yield point. Two nonlinear thermoviscoelastic plane stress constitutive models, one isotropic and one orthotropic, are developed using the Eyring stress shift factor to capture material nonlinearities, in the framework of the Boltzmann and the time–temperature superposition principles. A freezing of the Eyring shift factor during unloading has been introduced to represent ETFE relaxation and cyclic conditions. The numerical implementation of the consecutive models within finite element software is made available open source and has enabled the their validation on independently acquired data. The results show high accuracy between measurements and predictions from both isotropic and orthotropic formulations, thus paving the way for their use in structural design to capture highly nonlinear time and thermal effects, such as multiaxial prestress loss after installation or creep caused by variable loads.

Comparative Study of Core Material's Stiffness on Sandwich Panel with Composite Face Sheets beyond the Yield Point

The study aims to explore the performance of sandwich panels exceeding the yield point stiffness of the core material. Sandwich panels have gained growing attention among designers owing to their excellent corrosion properties, and lightweight, and speedy installation process. They have been applied in numerous industrial sectors, including aerospace, architectural, marine, and transportation. Typically, sandwich panels are composed of a single central core sandwiched by a pair of outer face sheets, where the core is normally developed using softer materials compared to the face sheets. Given that past studies have primarily focused on sandwich panels in the elastic range, this present study explored the performance of sandwich panels exceeding the yield point stiffness of the core material. The univariate search optimization method was utilized to assess the elastic modulus ratio of the core (typically foam) to the face sheet (composite material). The load was elevated in a quasi-static order until the face sheets reached their yield point. Subsequently, the panel was simulated using the finite element analysis commercial package ANSYS APDL, with simply supported boundary conditions used on all sides of the panel. The proposed model was verified by comparing the numerical and experimental data from recent literature. Based on the results, the panel's increased load-carrying capacity corresponded as the core material stiffness exceeded its yield limit. Moreover, the transmission of load to the face sheets increased as the core stiffness decreased. In summary, stiffer core materials caused the sandwich panel to behave more as isotopic face sheets. Thus, the face sheets yielded ahead of the core material.

Uniqueness of glasses prepared via x-ray induced yielding

The yield point marks the beginning of plastic deformation for a solid subjected to sufficient stress, but it can alternatively be reached by x-ray irradiation. We characterize this latter route in terms of thermodynamics, structure and dynamics for a series of GeSe3chalcogenide glasses with different amount of disorder. We show that a sufficiently long irradiation at room temperature results in a stationary and unique yielding state, independent of the initial state of the glass. The glass at yield is more disordered and has higher enthalpy than the annealed glass, but its properties are not extreme: they rather match those of a glass instantaneously quenched from a temperature 20% higher than the glass-transition temperature. This is a well-known, key temperature for glass-forming liquids which marks the location of a dynamical transition, and it is remarkable that different glasses upon irradiation head all there.

Preparation and Evaluation of a Novel Branched Polymer as Thickener for Calcium Chloride-Based Drilling and Completion Fluids

Preparation and Evaluation of a Novel Branched Polymer as Thickener for Calcium Chloride-Based Drilling and Completion Fluids

Dysphagia-oriented non-Newtonian flow analysis of mayonnaise on different timescales using large amplitude oscillatory shear (LAOS) models

Dysphagia is a condition that particularly affects the elderly, making dietary modification an essential treatment strategy. This involves using various thickened foodstuffs, which must be evaluated using unified, rheological, colloidal, and tribological techniques/standards. During swallowing, food bolus undergoes rapid, nonlinear, large deformations across a wide range of timescales. However, the ideal rheological profile for safe swallowing is still not known, and the study of foods under large deformation is inadequate. This work aimed to employ large-amplitude oscillatory shear (LAOS) analysis to describe the behavior of thicker foods under different timescales. Mayonnaise, a representative with complex rheological behaviors, is considered a suitable model for studying dysphagia-oriented foods. The study used multiple LAOS analysis models, including algebraic stress bifurcation to determine yield points, the Kamani–Donley–Rogers recovery rheology model to identify recoverable and unrecoverable components, and a data-driven constitutive model for precise LAOS behavior prediction. Other methods used included Fourier transform rheology, Lissajous curve, stress decomposition, strain-stiffening and shear-thickening ratios, dissipation ratio, and the sequence of physical processes. Importantly, it was observed that as the testing frequency increased, the apparent nonlinearity trajectories of mayonnaise collapsed inward with slight rotations. The timescale of deformation can strongly or weakly influence the intensity and type of non-Newtonian flows observed depending on the LAOS behaviors at different frequencies. This study enhanced the development and evaluation of dysphagia-oriented products at different timescales from a rheological perspective, which may bring new insight into the on-demand management of dysphagia and motivate innovative ideas in diet design and processing.

Evaluating eggshells as sustainable weighting agents in water-based drilling muds: A novel approach for enhanced efficiency and environmental consciousness

This study investigates the utilization of eggshells, a renewable material, as a weighting additive in water-based drilling muds with different exploring concentrations. The primary objectives were to assess the impact of eggshells on the rheological properties of drilling muds and to determine the optimal concentration of eggshells for achieving desired density and stability, drawing comparisons with calcium carbonate (CaCO3). Both eggshell powder (ESP) and CaCO3 effectively increase mud weight to the target density of 8.75 ppg at 30 g. Notably, ESP exhibits favorable rheological properties at 20 g, maintaining low plastic viscosity 2.7, consistent yield points 1.1, and gel strength comparable to CaCO3. Conversely, CaCO3 shows signs of potential deterioration at 30 g indicated by increased viscosity to 3.5 and decreased yield point to 0.5. ESP demonstrates superior filtration performance, displaying a progressive increase in cake thickness with increasing weight 1.32 mm to 3.12 mm compared to the slower cake build-up of CaCO3 0.92 mm to 2.9 mm. Both additives slightly elevate mud pH, potentially enhancing overall stability.

Experimental study of magnetorheological fluids under large periodic deformations

Abstract Magnetorheological (MR) fluids are smart materials whose properties can be controlled by a magnetic field. They are used in a variety of applications with tailored operating parameters, facilitating broad and relatively straightforward implementation and control of the functional properties of these systems.

The aim of the study was to determine the variation in shear stress of MR fluids under varying shear deformation directions and different magnetic field induction levels. The experiments were carried out with the use of three commercially available fluids: MRF-122EG, MRF-132DG, and MRF-140CG, which primarily differ in the volumetric fraction of ferromagnetic particles. These fluids are designed for use in mechanical energy dissipation devices clutches, and brakes are characterized by high stability and a broad controllability range.

The experiments were performed using a rotational rheometer with a parallel plate measuring system to examine shear stress variability during both the deformation and rest phases. The study applied relatively large deformations, exceeding the linear viscoelastic range and the deformation corresponding to the yield point.

The test results revealed variations in the shear stress values across successive loading cycles, as well as fluctuations during the rest phase. It was also found that, depending on magnetic field induction level (i.e., the level of fluid magnetization), the rest period could result in either a decrease (relaxation) or an increase (hardening) in shear stress values. These findings have practical significance, particularly for MR fluid devices operating in shear mode.

Performance Evaluation of Delonix regia Sawdust as Cement Retarder in Oil and Gas Well

Sawdust, a byproduct of wood exploitation and processing, poses environmental pollution risks if not managed appropriately. Its substantial carbon footprint can lead to pollution, habitat disruption, and fire hazards. However, repurposing sawdust as a chemical additive in cement slurry within the oil and gas industry offers an environmentally friendly solution. This practice aligns with sustainability goals, enhances cement slurry properties, promotes wellbore stability, and replaces more hazardous additives, thereby reducing environmental impact. This study is aimed at the production of a retarder (sodium lignin) from sawdust waste obtained from the Delonix regia species, and examining its effect on the thickening time/consistency, compressive strength, and rheological properties on the slurry of a Class G cement At a Bottom Hole Circulating Temperature (BHCT) of 90°C, thickening time tests conducted on the slurry samples revealed that as the concentration of the locally synthesized retarder increases, the thickening time of the concrete also increases, with minimal effect on compressive strength. The optimal thickening time result of 6 hours and 13 minutes was achieved with 0.5% Sodium Lignin (Retarder from Delonix regia sawdust) replacing a portion of the cement. At a bottomhole static temperature (BHST) of 100°C, increasing the concentration of the formulated sample led to higher Plastic Viscosities (PV) and yield points in the slurries. The findings indicate that slurries formulated with sodium lignin maintain viscosities within recommended values, making them suitable for pumping.

Electro‐Chemo‐Mechanical Domain to Enable Less Hysteretic Fast‐Charging

AbstractA new avenue by transforming the conventional electrochemical domain into an electro‐chemo‐mechanical domain is proposed to achieve less hysteretic fast‐charging based on the three pictures: i) electro‐chemo‐mechanics, ii) phase transition kinetics, and iii) ionic kinetics. Each concept is demonstrated leading to the electrochemical improvement using data‐driven computation and experimental analyses, and its novel framework is generalized based on alkali‐ion chalcogenide models. The mechanical strain lowers and delays the electrochemical yield point, which gives rise to extending the elastic region and enhancing the phase and ionic kinetics. This is experimentally verified with less hysteresis upon (dis)charging for all models. Implementing the electro‐chemo‐mechanical domain is central in alkali‐ion chalcogenide batteries and broadens its application in other rechargeable batteries, ultimately playing a critical role in providing practical fast‐charging solutions.

Effect of temperature on transport index of fish oil-based drilling mud in high pressure high temperature well: a hybrid model approach

Diesel Oil-based drilling mud used in the oil and gas industry causes severe environmental and public health issues due to its high toxicity, especially in high-pressure, high-temperature (HPHT) wells. Therefore, easily biodegradable synthetic oil-based mud with high drilling performance is essential. Fish oil is a bio-oil known for its non-toxicity, high lubricity, thermal stability, and biodegradability. Effective hole cleaning is crucial for drilling performance and is ensured by the rheological properties of drilling mud. While rheological parameter prediction can be performed using an artificial neural network (ANN) based model, such models often fail to provide accurate predictions for unseen data. In contrast, empirical models are more robust and facilitate generalization. This study aims at assessment of the suitability of invert emulsion fish oil-based drilling mud (IEFOBDM) in HPHT wells through evaluation of hole cleaning performance (HCP) using a hybrid approach that combines an ANN with nonlinear regression (NLR) for temperatures ranging from 40 °C to 80 °C.Firstly, an ANN model was developed considering mud weight, temperature, and shear rate. Secondly, the NLR model was used in the prediction of rheological parameters, namely, Yield point (YP) and Plastic viscosity (PV), based on the predicted shear stress from the ANN model. Finally, the performance metrics of the ANN-NLR rheological model were evaluated using the root mean square error (RMSE) and correlation coefficient (R2) and comparison made with the Single ANN rheological model. The results showed the outperformance of ANN-NLR model over the ANN model for rheological parameter prediction, with R2 values of (0.99) for YP and (1) for PV. The predicted PV and YP values were then used for evaluation of transport index (TI) for HCP analysis. The effect of temperature on TI analysis showed this with increase in temperature, TI also increased, indicating the proposed mud providing good HCP under HPHT conditions.

Effect of thread direction on rotational stability in lag-screw fixation of sacroiliac luxation: An ex vivo cadaveric study in small-breed dogs.

To assess the effect of screw thread direction on rotational resistance in canine sacroiliac (SI) luxation models using left- and right-handed screws. Controlled laboratory study. Twenty-four adult canine pelves with proximal femora were examined. Four groups (n = 6 each) were established: right-handed screw/right SI luxation (RhRSI), right-handed screw/left SI luxation (RhLSI), left-handed screw/left SI luxation (LhLSI), and left-handed screw/right SI luxation (LhRSI). Under fluoroscopy, 2.4 mm cortical screws were placed into the SI joint in a lag fashion. An acute failure test measured force and torque at yield and peak points, with the ilium and femur positioned at a 108° angle and displacement at 0.099 cm/s. Torque (N cm) was calculated from force (N) and the moment arm (cm). Differences in median torque were found at yield and peak points. RhRSI gave 50.08 N cm versus 16.01 N cm for RhLSI (p < .01), and LhLSI showed 39.42 N cm versus 19.93 N cm for LhRSI (p < .03). At peak, RhRSI recorded 67.55 N cm compared to 28.14 N cm for RhLSI (p < .01), and LhLSI reached 51.79 N cm versus 28.28 N cm for LhRSI (p < .05). All samples failed by rotation without screw breakage or fractures. Right-handed screws provided greater rotational resistance in right-sided luxation, and left-handed screws in left-sided luxation, which demonstrated that screw thread direction influenced fixation stability in SI luxation. The findings suggest that selecting screw thread direction can enhance biomechanical stability in SI luxation repair, improving surgical outcomes for affected dogs.

Analytical investigation on the rotational behavior of dovetail mortise–tenon joints between beams and columns in traditional Chinese timber frames

We theoretically analyzed the rotational behavior of beam–column dovetail joints in traditional Chinese timber frames in this study. An analytical model of dovetail joints at both the column head and body was designed by clarifying the moment generation mechanism and effect of rotational embedment yielding in timber perpendicular to the grain on the rotational behavior of joints. An asynchronous manifestation of rotational embedment deformation across the column surface, tenon cheeks, and upper and lower surfaces of the tenon head was analyzed, and the corresponding characteristic yield points and consequent reduction in rotational stiffness were derived in the model. The Inayama embedment theory was used to clarify the effect of rotational embedment with varying end lengths on the movement of the joint rotation center and asymmetric moment generated in different rotation directions of the column head joint. The precision of the analytical model was validated through a comparative analysis by involving nine sets of experimental data, for estimating the initial stiffness, post-yield stiffness, and identified yield points. The implications of the parameters, including the initial gap between the tenon and mortise, geometric dimensions of the dovetail tenon, and friction coefficient, were also discussed. Controlling the ratio of the initial gap and tenon height within 0.01 to ensure a certain rotational resistance of dovetail beam–column joints within the collapse limits of traditional timber frames is recommended considering the significant effect of the initial gap on the initial sliding angle and moment reduction.

Research on the Connection Technology of Assembled Monolithic Residential Wallboard

In this paper, a novel technique for connecting residential shear walls to floor slabs is investigated. Shear wall structures with two different connection methods were established and numerically analyzed using ABAQUS (2024) finite element software. The two structures were connected by sleeve grouted connections (hereinafter referred to as the original structure) and profile + bolted connections (hereinafter referred to as the new structure). Numerical analyses yielded a positive maximum load for the new structure 1.41 times that of the original structure and a negative maximum load 1.12 times that of the original structure. The ratio of the ultimate tensile strength (load value corresponding to the peak point) to the yield strength (load value corresponding to the yield point) of the two structures (strength-to-yield ratio) was in the range of 1.15–1.27. The original structure was 2.62 times more ductile in the negative direction and 2.24 times more ductile in the positive direction than the new structure. The stiffness degradation of the new structure was greater in the later stages of loading, and that of the original structure was greater in the early stages of loading. The original structure had 1.08 times the energy-consuming capacity of the new structure. The cost of labor and materials for the original structure was approximately 1.50 times the cost of the new structure. The results of the data analysis showed that, compared to the original structure, the new structure had comparable performance in terms of strength-to-flexure ratio, ductility, stiffness degradation, and energy dissipation capacity. However, the new structure was more advantageous in terms of load-bearing capacity and required lower construction costs than the original structure. Therefore, the connection nodes designed in this paper are of great significance for engineering practice.

Double Low‐Yield‐Point Steel Corrugated Plates as an Innovative Damper to Improve the Behavior of CBF Braces

ABSTRACTIn this paper, an innovative damper made of low yield point (LYP) steel compound of double corrugated plate and flange plates to form an I‐shaped damper was considered parametrically and numerically. This damper pertain to easy fabrication and replacement after a severe earthquake. The proposed damper is expected to yield while elements outside the damper remain elastic. Consequently, it acts as a ductile fuse that was confirmed in this study. Results indicated that changing the damper from conventional steel to LYP steel improves the damper's performance. Because dampers with the same exhibited different responses, classification of the damper response based on the is not approritae. Of course, considering the fact that it has shear behavior with can be used in the initial design, but it is an incomplete criterion. Also, for dampers with , the ultimate strength is increased related to the from 2.64 to 4.50 times whereas for and is reached 1.35 to 3.84 times and 1.34 to 3.80 times, respectively. It confirms that on the , the most effective on the ultimate strength is obtained by changing the A36 steel to LYP steel. It should be noted that by increasing the by two to four times, the energy dissipation is enhanced 1.44 to 5.64 times for LYP dampers and 1.15 to 2.02 times for A36 dampers.

Experimental investigation of biopolymers influences on rheology and filtration properties of water-based drilling fluids

Pipe-stuck, filtrate volume, and formation damage during the drilling operation are directly related to the poor performance of drilling fluids. Hence, considerable attention is required to improve the filtration and rheological properties of drilling fluids and achieve industrial and environmental qualification standards. This study experimentally investigates the impact of Pectin and Astragalus gum biopolymers on the filtration and rheological properties of the water-based drilling fluid (WBDF). It also compares the results with the base drilling fluid and those obtained by adding commercial xanthan gum to WBDF. Fourier Transform Infrared Spectroscopy, thermogravimetric analysis, Zeta potential, and Scanning Electron Microscopy are applied to characterize these additives. The viscosity, filtrate volume, gel strength, and yield point of these biopolymer-added WBDFs were experimentally measured and compared. Various rheological models have been examined to correlate the experimental data shear stress versus shear rate profiles. Also, the filtration characteristics of WBDF were analyzed at high-temperature and high-pressure conditions using the filter press. The results showed that biopolymer additives considerably improve WBDF performance. The fluid formulations with Pectin presented more advantages over the other two biopolymers regarding fluid cake formation and rheological properties. The WBDF containing xanthan gum, Pectin, and Astragalus gum decreases filtrate volume by 42.9 %, 55.7 %, and 48.6 %, and increases plastic viscosity by 34.4 %, 46.9 %, and 40.6 %, respectively. Also, 56.5 %, 73.9 %, and 78.3 % increases in the yield point of WBDFs were obtained by adding xanthan gum, Pectin, and Astragalus gum to WBDF, respectively. Generally, the viscosity and yield point were more stable for biopolymer additive drilling fluids at high temperatures. In addition, the results showed that adding Pectin would cause less formation damage. The experimental results show that the optimum concentration of xanthan gum, Pectin, and Astragalus gum is 1.4, 1, and 1.05 wt.%, respectively.

Real-Time Monitoring and Control System Enhances Drilling-Fluid Management

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 216322, “Next-Generation Drilling-Fluid Management: Real-Time Monitoring and Autonomous Control,” by Zhicai Zhang, Rached M. Rached, SPE, and Yunbo Xun, Sinopec, et al. The paper has not been peer reviewed. _ Accurate measurement and control of drilling-fluid properties are crucial for safe and successful drilling operations. Traditional manual methods are slow and require significant manpower, underscoring the need for real-time monitoring. This paper highlights a new online system for monitoring drilling fluids, enabling intelligent control of drilling-fluid performance. The online monitoring system improves drilling-industry safety and success by measuring properties of drilling fluids in an accurate, timely, and automated matter. Introduction The primary objectives of this project are to develop an innovative online system for monitoring drilling fluids with a focus on facilitating intelligent control of drilling-fluid performance. The system aims at measuring 10 key parameters continuously, including apparent viscosity, plastic viscosity, yield point, density, pH, and ion concentrations. By incorporating online, real-time, continuous monitoring capabilities, the system offers several advantages, including improved data quality and frequency, reduced on-site labor requirements, and a corresponding decrease in associated health and safety hazards. System Description Overview of the Online Drilling-Fluid-Monitoring System. The online drilling-fluid-monitoring system is available in four distinct configurations: land modular, land skid-mounted, offshore cabin, and indoor small modular, providing customization options to meet specific space requirements. The system is designed to measure 10 crucial parameters essential for drilling operations. These include rheology factors, density, pH, sulfur ion content, and chloride ion content. Density and rheology measurements are performed at a 1-Hz sampling rate, offering near-continuous monitoring. The system is capable of operating within an ambient temperature range from –35 to 50°C, and the testing temperature can be adjusted between 4 and 80°C. Enabled by real-time data transmission, the system allows for the online, real-time monitoring of drilling-fluid properties. The system has proven its utility extensively, with more than 30 sets having been deployed successfully across more than 200 wells. Ideally, the monitoring system is positioned near the circulation tank to enable efficient fluid transfer (Fig. 1a). When space near the circulation tank is limited, an alternative placement can be on the opposite side of the blowout-prevention pipeline (Fig. 1b). However, this alternative may lead to a slight delay in data because of extended circulation times.

Altered post-fracture systemic bone loss in a mouse model of osteocyte dysfunction.

Femur fracture leads to loss of bone at uninjured skeletal sites, which may increase risk of subsequent fracture. Osteocytes, the most abundant bone cells, can directly resorb bone matrix and regulate osteoclast and osteoblast activity, but their role in systemic bone loss after fracture remains poorly understood. In this study we used a transgenic (TG+) mouse model that overexpresses human B-cell lymphoma 2 (BCL-2) in osteoblasts and osteocytes. This causes enhanced osteoblast proliferation, followed by disruption in lacunar-canalicular connectivity and massive osteocyte death by 10wk of age. We hypothesized that reduced viable osteocyte density would decrease the magnitude of systemic bone loss after femur fracture, reduce perilacunar remodeling, and alter callus formation. Bone remodeling was assessed using serum biomarkers of bone formation and resorption at 5d post-fracture. We used micro-computed tomography, high resolution x-ray microscopy, mechanical testing, and Raman spectroscopy to quantify the magnitude of systemic bone loss, as well as changes in osteocyte lacunar volume, bone strength, and bone composition 2wk post-fracture. Fracture was associated with a reduction in circulating markers of bone resorption in non-transgenic (TG-) animals. TG+ mice exhibited high bone mass in the limbs, greater cortical elastic modulus and reduced post-yield displacement. After fracture, TG+ mice lost less trabecular bone than TG- mice, but conversely TG+ mice exhibited trends toward a lower yield point and reduced femoral cortical thickness after fracture, though these were not statistically significant. Lacunar density was greater in TG+ mice, but fracture did not alter lacunar volume in TG+ or TG- mice. These findings suggest that osteocytes potentially play a significant role in the post-traumatic systemic response to fracture, though the effects differ between trabecular and cortical bone.

Przygotowanie i poprawa właściwości reologicznych naturalnego bentonitu przy użyciu węglanu sodu i karboksymetylocelulozy sodu

Drilling fluids play a critical role in the exploration and production of oil and gas. Among the various types of drilling fluids, water-based mud has attracted significant attention due to its sustainability and low cost compared to synthetic mud. In Kenya, there is an increasing demand for sustainable drilling fluid compounds, such as bentonite, which is readily available in some parts of the country, for example, Isinya and Amboseli. The main drawback for the beneficiation of Kenyan bentonite include low concentration of smectite, high levels of iron contaminant, and inconsistent composition. Hence, there is a need to enhance local bentonite to improve its performance for effective drilling applications. In this work, we incorporated sodium carbonate (Na2CO3) and carboxymethyl cellulose (CMC) as additives to improve the properties of the raw bentonite. The rheological characteristics of both pristine and activated bentonite were investigated using the Rheolab QC rheometer. The findings revealed that the yield point of the Isinya and Amboseli samples increased as a function of the levels of activation reagents (Na2CO3 and CMC). It was noted that more than 1.25w% of Na2CO3 was required to bring the yield stress closer to the required 15 Pa for drilling application. Additionally, the Isinya bentonite (IS3) provided adequate rheological characteristics for drilling muds after compounding with 2.5w% CMC additive. These results demonstrate the feasibility of using the local bentonite in Kenya for drilling applications. In the future, we will explore the potential of using other additives to further enhance the properties of local bentonite for geothermal power production, with the goal of lowering electricity generation cost and supporting ongoing efforts to provide reliable and affordable energy, as proposed in Kenya Vision 2030 project.