From the coal gasification technology, coarse slag (GFS) is derived, a byproduct containing substantial quantities of amorphous aluminosilicate minerals. GFS's low carbon content and the pozzolanic potential of its ground powder make it a useful supplementary cementitious material (SCM) in cement applications. The investigation of GFS-blended cement included detailed analyses of ion dissolution properties, initial hydration rate and process, hydration reaction mechanisms, microstructure evolution, and the development of mechanical strength in its paste and mortar forms. GFS powder's pozzolanic activity is potentially enhanced by the combination of elevated temperatures and amplified alkalinity. BRD7389 price Altering the specific surface area and content of GFS powder did not impact the reaction mechanism of cement. The hydration process was segmented into three key stages: crystal nucleation and growth (NG), phase boundary reaction (I), and diffusion reaction (D). GFS powder exhibiting a larger specific surface area might expedite the chemical kinetic processes occurring within the cement. The reaction of GFS powder and blended cement exhibited a positive correlation. The remarkable activation and subsequent improved late-stage mechanical properties of the cement were a direct outcome of utilizing a low GFS powder content (10%) and its exceptional specific surface area (463 m2/kg). Results confirm that GFS powder with a low carbon composition has practical use as a supplementary cementitious material.
Falls can severely impact the quality of life of older people, making fall detection a crucial component of their well-being, especially for those living alone and sustaining injuries. In the same vein, the detection of near falls— instances of pre-fall imbalance or stumbles—promises to proactively prevent the actual occurrence of a fall. This research focused on developing a wearable electronic textile device to detect falls and near-falls, and leveraged a machine learning algorithm to effectively interpret the resulting data. A significant goal behind this study was crafting a wearable device that individuals would find comfortable and hence, use. Electronic yarn, motion-sensing and singular in each, was employed in the design of a pair of over-socks. A trial involving thirteen participants employed the use of over-socks. Three different types of daily living activities (ADLs) were performed by the participants, along with three distinct types of falls onto the crash mat and a single instance of a near-fall. A machine learning algorithm was employed to classify the trail data, which was previously analyzed visually for discernible patterns. The over-socks, developed and paired with a bidirectional long short-term memory (Bi-LSTM) network, have demonstrated the capability to distinguish between three distinct activities of daily living (ADLs) and three distinct falls, achieving an accuracy of 857%. Furthermore, the system accurately differentiated between ADLs and falls, achieving an accuracy of 994%. Finally, the integration of stumbles (near-falls) with ADLs and falls yielded an accuracy of 942%. Moreover, the outcomes demonstrated that the motion-sensitive E-yarn is necessary solely in one over-sock.
Welded zones of newly developed 2101 lean duplex stainless steel, which had been flux-cored arc welded using an E2209T1-1 flux-cored filler metal, showed the presence of oxide inclusions. The welded metal's mechanical strength and other properties are directly correlated to the presence of these oxide inclusions. Therefore, a correlation, requiring verification, has been established between oxide inclusions and mechanical impact toughness. Accordingly, the employed research methods included scanning electron microscopy and high-resolution transmission electron microscopy to determine the correlation between oxide inclusions and the mechanical impact strength of the material. The spherical oxide inclusions, which were found to consist of a mixture of oxides, were situated near the intragranular austenite within the ferrite matrix phase, based on the investigations. The deoxidation of the filler metal/consumable electrodes led to the formation of oxide inclusions, specifically titanium- and silicon-rich amorphous oxides, MnO in a cubic configuration, and TiO2 exhibiting orthorhombic/tetragonal structures. We also discovered that oxide inclusion types did not have a substantial impact on energy absorption, and no crack formation occurred near them.
The stability of the Yangzong tunnel, especially during excavation and long-term maintenance, is strongly influenced by the instantaneous mechanical properties and creep behaviors of the surrounding dolomitic limestone, the primary rock material. Four conventional triaxial compression tests were implemented to ascertain the limestone's instantaneous mechanical behavior and failure mechanisms. Subsequently, the creep behavior of the limestone under multi-stage incremental axial loading was studied, utilizing a state-of-the-art rock mechanics testing system (MTS81504) and confining pressures of 9 MPa and 15 MPa. The following findings are evident from the results. Analyzing the relationship between axial, radial, and volumetric strain and stress, across a range of confining pressures, displays a similar trajectory for these curves. The decline in stress after peak load, however, diminishes more gradually with higher confining pressures, indicating a shift from brittle to ductile rock failure. The confining pressure has a specific impact on the degree of cracking deformation during the pre-peak stage. Moreover, the distribution of compaction and dilatancy-dominated phases in the volumetric strain-stress curves varies significantly. The fracture mode of the dolomitic limestone, being shear-dominated, is, however, contingent upon the prevailing confining pressure. Reaching the creep threshold stress within the loading stress initiates a sequential progression of primary and steady-state creep stages, a greater deviatoric stress yielding a larger creep strain. Deviatoric stress exceeding the accelerated creep threshold stress results in the emergence of tertiary creep, ultimately causing creep failure. Significantly, the threshold stresses at 15 MPa confinement are superior to the corresponding values at 9 MPa confinement. This finding underscores the tangible effect of confining pressure on the threshold values, and a stronger relationship exists between higher confinement and higher threshold values. The specimen's creep failure mode involves a sharp, shear-dominant fracture, analogous to the failure mode seen in high-pressure triaxial compression tests. A comprehensive nonlinear creep damage model, consisting of multiple elements, is developed by connecting a proposed visco-plastic model in series with a Hookean substance and a Schiffman body, thus offering a precise characterization of the entire creep progression.
The objective of this study is to synthesize MgZn/TiO2-MWCNTs composites that exhibit varying TiO2-MWCNT concentrations, accomplishing this through a combination of mechanical alloying, semi-powder metallurgy, and spark plasma sintering procedures. This project additionally involves examining the mechanical, corrosion, and antibacterial properties displayed by these composites. The MgZn/TiO2-MWCNTs composites showed superior microhardness, 79 HV, and compressive strength, 269 MPa, respectively, in comparison to the MgZn composite. Cell culture and viability experiments on the TiO2-MWCNTs nanocomposite demonstrated an increase in osteoblast proliferation and attachment, leading to better biocompatibility. BRD7389 price Following the addition of 10 wt% TiO2-1 wt% MWCNTs, the corrosion resistance of the Mg-based composite was augmented, leading to a reduction in the corrosion rate to about 21 mm/y. In vitro testing, lasting up to two weeks, demonstrated a slower degradation rate when TiO2-MWCNTs were added to a MgZn matrix alloy. Antibacterial tests on the composite revealed activity against Staphylococcus aureus, characterized by an inhibition zone of 37 mm. The MgZn/TiO2-MWCNTs composite structure holds immense promise for applications in orthopedic fracture fixation devices.
Magnesium-based alloys produced via mechanical alloying (MA) exhibit characteristics of specific porosity, a fine-grained structure, and consistent isotropic properties. Magnesium, zinc, calcium, and the precious element gold are present in biocompatible alloys, which are suitable for use in biomedical implants. The potential of Mg63Zn30Ca4Au3 as a biodegradable biomaterial is assessed in this paper, including an analysis of selected mechanical properties and structure. The article details the results of X-ray diffraction (XRD), density, scanning electron microscopy (SEM), particle size distribution, Vickers microhardness, and electrochemical properties assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic immersion testing, all stemming from an alloy produced by 13-hour mechanical synthesis and subsequently spark-plasma sintered (SPS) at 350°C and 50 MPa pressure with a 4-minute hold and heating rates of 50°C/min to 300°C and 25°C/min from 300°C to 350°C. Through the study, the compressive strength was discovered to be 216 MPa and the Young's modulus 2530 MPa. The structure's phases include MgZn2 and Mg3Au, products of mechanical synthesis, along with Mg7Zn3, a result of the sintering process. MgZn2 and Mg7Zn3 contribute to improved corrosion resistance in magnesium-based alloys, however, the double layer arising from exposure to Ringer's solution proves ineffective as a barrier; therefore, further data acquisition and optimization protocols are essential.
Numerical methods are commonly utilized to model the propagation of cracks in quasi-brittle materials, like concrete, experiencing monotonic loading. Nevertheless, a deeper investigation and subsequent interventions are crucial for a more comprehensive understanding of fracture behavior subjected to cyclical stress. BRD7389 price Numerical simulations of mixed-mode concrete crack propagation are carried out in this study using the scaled boundary finite element method (SBFEM). The cohesive crack approach, combined with the thermodynamic framework of a concrete constitutive model, forms the basis for crack propagation development. Two benchmark fracture cases are modeled under conditions of either consistent or cyclical stress.