A 70% increase in mass was observed in the graphene sample after undergoing the carbonization process. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and adsorption-desorption techniques were used to characterize the properties of the B-carbon nanomaterial. A boron-doped graphene layer's addition to the existing structure resulted in an increase of the graphene layer thickness from 2-4 to 3-8 monolayers. This was accompanied by a decline in specific surface area from 1300 to 800 m²/g. The boron content of the B-carbon nanomaterial, quantified using different physical methods, was approximately 4 percent by weight.
A prevailing approach to lower-limb prosthetic design and manufacturing is the workshop method of iterative testing, utilizing expensive, non-recyclable composite materials. This results in a time-intensive process, significant material waste, and ultimately, high-cost prostheses. Thus, we explored the option of utilizing fused deposition modeling 3D printing with inexpensive bio-based and biodegradable Polylactic Acid (PLA) material for creating and manufacturing prosthetic sockets. By applying a recently developed generic transtibial numeric model, the safety and stability of the proposed 3D-printed PLA socket were assessed, considering donning boundary conditions and newly developed realistic gait phases of heel strike and forefoot loading, as specified in ISO 10328. The material properties of the 3D-printed PLA were established via uniaxial tensile and compression tests performed on transverse and longitudinal samples. The 3D-printed PLA and the traditional polystyrene check and definitive composite socket were subjected to numerical simulations, encompassing all boundary conditions. Analysis of the results revealed that the 3D-printed PLA socket endured von-Mises stresses of 54 MPa and 108 MPa during, respectively, heel strike and push-off gait phases. Correspondingly, the maximum distortions in the 3D-printed PLA socket at 074 mm and 266 mm, respectively during heel strike and push-off, were similar to the check socket's distortions of 067 mm and 252 mm, respectively, thereby providing the same stability for amputees. Pacritinib Our findings suggest the suitability of an inexpensive, biodegradable, and bio-based PLA material for creating lower-limb prosthetics, presenting a cost-effective and eco-friendly approach.
Textile waste is built up over a series of steps, starting with the preparation of the raw materials and extending through to the use of the textiles. The production of woolen yarn is a factor in the overall amount of textile waste. Woolen yarn production generates waste products at various points, including the mixing, carding, roving, and spinning processes. This waste finds its way to landfills or cogeneration plants for disposal. However, recycling textile waste to produce novel products is a common occurrence. This study investigates the application of woollen yarn manufacturing waste in the fabrication of acoustic boards. Waste material from various yarn production processes was accumulated throughout the stages leading up to spinning. This waste's unsuitability for further yarn production stemmed from the parameters in place. The study, carried out during the woollen yarn production process, involved a comprehensive analysis of waste composition, encompassing fibrous and non-fibrous materials, the composition of impurities, and the physical and chemical characteristics of the fibres. Pacritinib Further investigation confirmed that nearly three quarters of the waste can be employed for crafting acoustic boards. Four series of boards, exhibiting distinct density and thickness properties, were fabricated utilizing waste products stemming from the production of woolen yarns. Semi-finished boards, a product of carding technology in a nonwoven line, were formed from individual combed fibers. These semi-finished products then underwent thermal treatment. The sound reduction coefficients were calculated using the sound absorption coefficients determined for the manufactured boards, across the range of frequencies from 125 Hz to 2000 Hz. A study revealed that acoustic properties of softboards crafted from recycled woollen yarn closely resemble those of traditional boards and sustainable soundproofing materials. For a board density of 40 kg per cubic meter, the sound absorption coefficient displayed a spectrum from 0.4 to 0.9, and the noise reduction coefficient reached 0.65.
Given the increasing importance of engineered surfaces enabling remarkable phase change heat transfer in thermal management applications, the fundamental understanding of the intrinsic effects of rough structures and surface wettability on bubble dynamics warrants further exploration. Employing a modified molecular dynamics simulation, this work investigated bubble nucleation on rough nanostructured substrates having diverse liquid-solid interactions in the context of nanoscale boiling. Quantitatively analyzing bubble dynamics under a variety of energy coefficients was the focus of this study on the initial nucleate boiling stage. Observations indicate that a reduction in contact angle is accompanied by a rise in nucleation rate. This phenomenon stems from the enhanced thermal energy absorption by the liquid at these lower contact angles, in contrast to situations with inferior wetting properties. Initial embryos can be facilitated by nanogrooves, which in turn result from the substrate's rough morphology, thereby improving the efficiency of thermal energy transfer. The formation of bubble nuclei on differing wetting substrates is explicated via calculated and adopted atomic energies. Future surface design strategies for state-of-the-art thermal management systems, including surface wettability and nanoscale surface patterns, are anticipated to be informed by the simulation outcomes.
Functional graphene oxide (f-GO) nanosheets were synthesized in this investigation for the purpose of improving the NO2 resistance of room-temperature-vulcanized (RTV) silicone rubber. A nitrogen dioxide (NO2) accelerated aging experiment, simulating the aging of nitrogen oxide produced by corona discharge on a silicone rubber composite coating, was devised, and electrochemical impedance spectroscopy (EIS) was employed to assess the penetration of conductive media into the silicone rubber. Pacritinib Exposure to 115 mg/L NO2 for 24 hours, with an optimal filler content of 0.3 wt.%, yielded a composite silicone rubber sample with an impedance modulus of 18 x 10^7 cm^2. This is an order of magnitude greater than that of pure RTV. Increased filler content correspondingly diminishes the coating's porosity. At a nanosheet concentration of 0.3 weight percent, the porosity of the composite silicone rubber reaches a minimum of 0.97 x 10⁻⁴%, a figure one-quarter of the pure RTV coating's porosity. This highlights the material's remarkable resistance to NO₂ aging.
Heritage building structures are frequently a source of unique value and integral part of a nation's cultural heritage in numerous situations. Engineering practice mandates visual assessment as part of the monitoring regime for historic structures. This article investigates the present condition of the concrete in the prominent former German Reformed Gymnasium, located on Tadeusz Kosciuszki Avenue within Odz. The paper documents a visual evaluation of the building's structural components, pinpointing the impact of technical wear. A historical evaluation encompassed the building's state of preservation, the structural system's description, and the assessment of the floor-slab concrete's condition. The eastern and southern facades of the building were found to be in satisfactory condition, but the western facade, including the area surrounding the courtyard, required extensive restoration efforts. Concrete samples extracted from individual ceilings were also subjected to testing procedures. The concrete cores were examined for characteristics including compressive strength, water absorption, density, porosity, and carbonation depth. The analysis of concrete, utilizing X-ray diffraction, revealed details of corrosion processes, specifically the degree of carbonization and the phase composition. Concrete produced more than a century ago displayed high quality, as indicated by the results.
Seismic performance testing was undertaken on eight 1/35-scale models of prefabricated circular hollow piers. Socket and slot connections and polyvinyl alcohol (PVA) fiber reinforcement within the pier body were key components of the tested specimens. Among the test variables in the main test were the axial compression ratio, the quality classification of the pier concrete, the shear-span ratio, and the reinforcement ratio of the stirrups. A study on the seismic behavior of prefabricated circular hollow piers encompassed an examination of failure modes, hysteresis patterns, load-bearing characteristics, ductility indices, and energy dissipation capabilities. The test results, combined with the subsequent analysis, showed that each specimen failed due to flexural shear. Increasing the axial compression and stirrup ratios intensified concrete spalling at the base; however, PVA fibers lessened this degradation. Specimen bearing capacity may be augmented by increasing axial compression ratio and stirrup ratio, concurrent with reducing shear span ratio, within a specific range. Nevertheless, an overly high axial compression ratio can readily reduce the ductility exhibited by the specimens. Variations in the stirrup and shear-span ratios, prompted by height changes, contribute to a rise in the specimen's capacity for energy dissipation. This study introduced a shear capacity model for the plastic hinge region of prefabricated circular hollow piers, and the predictive power of different shear capacity models was compared against test data.