Search Results (729)

This study investigates the mechanical behavior of Nylon 12 Carbon Fiber specimens manufactured through fused filament fabrication (FFF) for potential integration into light water well drilling rigs. Fifteen tensile test samples were 3D-printed on a MakerBot Method X printer in three orientations: horizontal, vertical, and lateral. Each specimen was printed with a soluble SR-30 support material, which was subsequently dissolved in an SCA 1200-HT wash station using heated alkaline solution. Following support removal, all samples underwent thermal annealing at 80 °C for 5 h in the printer’s controlled chamber to eliminate residual moisture and improve structural integrity. The annealed specimens were subjected to uniaxial tensile testing using an Instron 8875 electrohydraulic machine, with strain measured by digital image correlation (DIC) on a speckle-patterned gauge section. Key mechanical properties, including Young’s modulus, Poisson’s ratio, yield strength, and ultimate tensile strength, were determined. Finally, a finite element analysis (FEA) was performed using MSC Visual Nastran for Windows to simulate the tensile loading conditions and assess internal stress distributions for each print orientation. The combined experimental and numerical results confirm the feasibility of using additively manufactured parts in demanding engineering applications. Full article

How to rationally design composition of alloys with desired properties has always been an open and challenging question, especially for high-entropy alloy (HEA) which has huge selections of composition due to the feature of multi-principal elements. Although great efforts have been made in the past decades, such as approaches based on thermo-kinetic analysis and simulations, strategies to quick determine the optimal HEA composition remain lacking. In this study, based on the effective estimations of elastic modulus of alloys from compositions, we proposed a strategy to design intrinsically strong, ductile, and low-weight refractory HEA (RHEA) compositions. First, the Young’s moduli of three RHEAs were experimentally measured using uniaxial tensile test and impulse excitation of vibration (IEV) test. Then, the present results, combining with the data of elastic moduli of ~130 HEAs in literature, were utilized to validate the prediction of elastic moduli from compositions of HEAs. Finally, based on the property maps that containing 38,326 compositions, a novel RHEA was designed and experimentally tested, exhibiting superior strength, ductility, and low density compared to the equimolar NbMoTaVW alloy. This study provides a new strategy for developing HEAs and contributes to the development of new refractory HEAs with desired properties. Full article

In this study, AlGaN/GaN heterostructure field-effect transistors (HFETs) with an AlN cap layer and a GaN cap layer were fabricated. The devices were of different sizes. Capacitance–voltage (C-V) and current–voltage (I-V) curves were measured. Based on two-dimensional (2D) scattering theory, electron mobility corresponding to polarization Coulomb field (PCF) scattering and other primary scattering mechanisms was quantitatively determined. The influence of the AlN cap layer on PCF scattering in AlGaN/GaN HFETs was studied. It was found that the AlN cap layer suppresses the inverse piezoelectric effect (IPE) in the AlGaN barrier layer because of its greater polarization and larger Young’s modulus, thereby reducing the generation of additional polarization charge (APC) under the gate. In addition, the 2D electron gas (2DEG) density (n_2DEG) under the gate of the samples with an AlN cap layer is higher. Both factors help reduce PCF scattering intensity. Moreover, mobility analysis of samples with different gate–drain spacings (L_GD) showed that PCF scattering is less affected by L_GD variations in devices with AlN cap layers. This study offers new insights into the structural optimization of AlGaN/GaN HFETs. Full article

In the absence of standard procedures for testing 3D-printed soft polymers, an experimental protocol was proposed to assess the suitability of Flexible 80A Resin for a pediatric trachea anatomical 3D model for surgical simulation. Eighteen specimens printed via stereolithography are involved, including anatomical, cylindrical, and dog-bone shapes, to investigate the geometry effect on measured properties. Static tensile tests revealed that using standardized dog-bone specimens as a reference for the material’s Young’s modulus leads to a mean absolute percentage error (MAPE) up to 50% compared to anatomical specimens. Measurement uncertainty combined repeatability with input errors, and the ANOVA test confirmed the need for dedicated mechanical measurements when evaluating complex 3D-printed geometries. The study concludes the suitability of selected material: the average elastic modulus of anatomical specimens was 4.75 MPa, closely matching values reported for tracheal tissue in the literature, with a MAPE of only 2%. Dynamic mechanical tests showed trachea-like viscoelasticity: anatomical specimens were consistently stiffer and more dissipative than cylindrical ones. Creep tests confirmed the viscoelastic behavior simulating airway time scales. The anatomical specimens exhibit faster local relaxation, while cylindrical ones show slower long-term relaxation, both modeled by a two-element generalized Maxwell model (R² = 0.99 and 0.98). Full article

Gallium-based liquid metal is corrosive to steel alloys, forming FeGa₃ surface films which can potentially be applied as a solid lubricant to enhance wear resistance and mitigate liquid metal-induced corrosion. However, the characteristics of these films remain insufficiently explored. In this study, Ga-In-Sn alloy was ultrasonically soldered onto annealed and decarburised substrates, followed by heating in a vacuum chamber to form a 30 μm thick FeGa₃ reaction layer. The film on the annealed samples with an alpha-ferrite microstructure exhibited high porosity and a surface roughness of 1.97 Ra. In contrast, the film on the decarburised samples with a ferritic microstructure showed minimal porosity and a lower surface roughness of 1.29 Ra. Nanoindentation tests revealed Young modulus values of 231 GPa and 242 GPa and hardness values of 11.4 GPa and 12.7 GPa for the annealed and decarburised samples, respectively. The high porosity in the annealed samples is attributed to the suppression of FeGa₃ formation in regions containing chromium carbides. Shear stress for fracture, measured by microcantilever tests at the interface between the substrate and the inner matrix of the surface film, showed lower fracture shear stress in the annealed sample, attributed to the presence of larger pores within its microstructure. Full article

Herein, biobased 1:1 lignin/polylactic acid (PLA) blends are electrospun into micro- and nanofiber mats. Lignin samples originating from softwood, hardwood, and switchgrass biomass, extracted through the Kraft, Alcell, and CELF processes, respectively, and processed into soluble and insoluble fractions, are used. Functional properties of the mats varied with lignin biomass origin, isolation method, and fraction. Mat attributes are demonstrated through analysis of spinnability, thermal and mechanical behavior, chemical structure, morphology, hydrophobicity, and antioxidant activity. Samples spun with hardwood Alcell lignin fractions were brittle and rigid with the highest Young’s modulus, lowest elongation at break, and hydrophobic contact angle > 100°. Switchgrass CELF lignin (SGL)/PLA mats showed the highest tensile strength, a low Young’s modulus, and high elongation at break, as well as good spinnability with the smallest fiber diameter from all samples. Kraft lignin/PLA demonstrated similar mechanical properties to SGL/PLA, as well as the highest antioxidant activity, measurable within 5 min. Therefore, while they did not dictate spinnability, the lignin biomass origin and pretreatment method were shown to have a significant impact on fiber properties, while the use of lignin fractions was shown to tailor functional properties of fibers for specific end use, such as in flexible, hydrophobic, or antioxidant product applications. Full article

In this study, the properties of Cu(Co) alloy films were investigated to assess their utility as an alternative material for interconnections in hybrid bonding applications. Thin films of Cu(Co) were deposited using electrochemical deposition in a standard sulfate-based electrolyte. X-ray photoelectron spectroscopy (XPS) of the films revealed that an increasing current density during deposition resulted in an increase in cobalt concentration. Bright-field scanning transmission electron microscopy (STEM) coupled with energy-dispersive x-ray spectroscopy (EDS) was used to visualize the fine-grained microstructure and confirmed grain boundary segregation of cobalt in the films. X-ray diffraction with a heated stage determined that the coefficient of thermal expansion (CTE) increased linearly with increasing cobalt content, from 17.5 ppm/K for pure copper to a maximum of 27.5 ppm/K for a film containing 24 at.% Co. Nanoindentation experiments found that the mechanical properties depended non-linearly on composition, with hardness increasing from 3.5 GPa for a 0% cobalt film to a maximum of 4.5 GPa (24 at.% Co) and the Young’s modulus increasing from 118 GPa to 214 GPa, respectively. Four-point probe electrical measurements confirmed the expected linear increase in resistivity as Co content increased. Since electrical and mechanical properties have differing dependences on the film composition, an optimal alloy composition that balances an acceptable increase in resistance with improved mechanical properties could enable more reliable, low-temperature bonding solutions in advanced microelectronic devices. Full article

Organosilica films, composed of a silicon oxide network with terminal methyl groups, are widely utilized in various applications, including microelectronics. Many of these applications require high hydrophobicity and good mechanical properties, which pose a significant challenge because the Si–CH₃ groups disrupt the Si–O–Si network. This issue becomes particularly pronounced in porous films. Here, we investigate whether material properties can be tuned by simply altering the spatial arrangement of methyl groups. To achieve this, we prepared copolymer films with one or two methyl groups bonded to a silicon atom, while maintaining a constant total amount of methyl groups. The films were deposited using a sol–gel technique combined with template self-assembly. The precursor content was varied to compare films with different proportions of Si–CH₃ and Si(–CH₃)₂. Film characterization included FTIR, ellipsometric porosimetry, AFM, and WCA measurements and dielectric constant evaluations. Our findings indicate that precursors containing dimethyl groups enhance the connectivity of the Si–O–Si network, resulting in a higher Young’s modulus and smaller pore size compared to films with an equivalent amount of methyl groups. However, the lower thermal stability of dimethyl bonds limits the thermal budget of these films. Thus, the spatial arrangement of organic groups within the polymer structure can be employed to tune material properties. These results expand the understanding of organic–inorganic hybrid materials and offer novel approaches for their applications. Full article

The fuel electro-hydraulic servo valve is a core component of the aero-engine fuel control system, playing a crucial role in engine performance. Due to the operational characteristics of the aviation fuel supply and injection system, fuel is directly sprayed through the nozzle for combustion after passing through the pipeline. The working environment and medium are subject to a wide temperature range, and the medium lacks a circulating filtration process, making it difficult to effectively remove impurities. As a result, the fuel contains a high concentration of contaminant particles. Under high-temperature conditions, colloidal particles precipitated from the fuel medium collide and adhere to metallic and other contaminant particles carried by the fuel, subsequently attaching to the internal surfaces of the fuel servo valve, causing valve sticking. This study aims to establish an adhesion criterion suitable for colloidal particles in fuel systems based on a traditional particle collision model. The adhesion criterion incorporates the viscoelastic and surface energy characteristics of colloidal particles, providing a more accurate description of their deposition behavior under the conditions studied. A particle–particle and particle–wall collision test apparatus was designed, and experiments were conducted. A comparison between experimental results and theoretical calculations shows that the overall error for collisions between colloidal particles and walls is controlled within 10%, validating the feasibility of the adhesion criterion. The Young’s modulus, Poisson’s ratio, and surface free energy of the colloidal particles were measured as 688 MPa, 0.39, and 77 mJ/m², respectively. These results provide theoretical and experimental foundations for particle migration and deposition processes in fuel systems. The analytical method clarifies the key mechanism of adhesion caused by colloidal particles, providing guidance for improving the reliability, safety, and maintenance of fuel servo valves in aero-engine applications. Full article

Objectives: To investigate the correlation between intraoperative conventional ultrasound, SWE, and SMI ultrasound manifestations of glioma and the expression of immunohistochemical markers. Methods: Patients with single superficial supratentorial glioma scheduled for brain tumor resection in our neurosurgery department from October 2020 to October 2022 were prospectively included. High-grade glioma (HGG) and low-grade glioma (LGG) were classified by pathological histological grading, and the differences in conventional ultrasound, SWE Young’s modulus, and SMI intratumoral and peritumoral blood flow architecture between HGG and LGG were analyzed, and the SWE diagnostic cut-off value was calculated by the Youdon index. Logistic regression models were used to analyze the independent predictive ultrasound signs associated with the diagnosis of HGG. HGG and LGG were classified by pathological histological grading. IDH1 expression was measured by immunohistochemical methods to analyze the correlation between IDH1 expression in glioma and clinical and ultrasound characteristics. Results: Forty-eight patients with glioma admitted to our hospital from October 2020 to October 2022 were included in this study, including 30 (62.5%) with HGG and 18 (37.5%) with LGG. For conventional ultrasound, HGG was often associated with severe peritumoral edema compared with LGG (p = 0.048). The sensitivity of HGG was 88.9%, the specificity was 86.7%, and the AUC was 0.855 (95% confidence interval: 0.741–0.968, p = 0.001) using Young’s mode 13.90 kPa as the threshold. Logistic analysis showed that SWE Young’s modulus values, and peritumoral and intratumoral SMI blood flow structures, were associated with the diagnosis of HGG. Among the 48 gliomas, 22 (45.8%) were IDH1-positive and 26 (54.2%) were IDH1-negative, with no statistical difference in age between the two groups and a statistical difference in histological grading (p < 0.05). There was a statistical difference between IDH1 mutant and wild type in terms of peritumoral edema and SMI intratumoral and peritumoral tissue vascular architecture. Logistic regression models showed that intratumoral and peritumoral tissue SMI vascular architecture was a valid predictor of IDH1 positivity, with a classification accuracy of 81.3%, sensitivity of 90.9%, and specificity of 73.1%. Further group analysis of mutant Young’s modulus values in LGG were higher than wild-type Young’s modulus values (p = 0.031). Conclusions: Peritumoral and intratumoral tissue SMI vascular architecture was a valid predictor of IDH1 positivity. Based on intraoperative ultrasound multimodality images, we can preoperatively determine the expression of molecular markers of lesions, which is of clinical significance for optimizing surgical strategies and predicting prognosis. Full article

The depletion of fossil fuels and the rise of environmental concerns have increased the importance of renewable energy sources, positioning wind energy as a key alternative. Modern wind turbine blades are predominantly manufactured from composite materials due to their light weight, high strength, and resistance to corrosion. In offshore applications, approximately 95% of the composite content is glass fiber-reinforced polymer (GFRP), while the remaining 5% is carbon fiber-reinforced polymer (CFRP). GFRP is favored for its low cost and fatigue resistance, whereas CFRP offers superior strength and stiffness but is limited by high production costs. This study investigates the durability of adhesively bonded GFRP and CFRP joints under marine exposure. Seven-layer GFRP and eight-layer CFRP laminates were produced using a 90° unidirectional twill weave and prepared in accordance with ASTM D5868-01. Specimens were immersed in natural Aegean Sea water (21 °C, salinity 3.3–3.7%) for 1, 2, and 3 months. Measurements revealed that GFRP absorbed significantly more moisture (1.02%, 2.97%, 3.78%) than CFRP (0.49%, 0.76%, 0.91%). Four-point bending tests conducted according to ASTM D790 showed reductions in Young’s modulus of up to 9.45% for GFRP and 3.48% for CFRP. Scanning electron microscopy (SEM) confirmed that moisture-induced degradation was more severe in GFRP joints compared to CFRP. These findings highlight the critical role of environmental exposure in the mechanical performance of marine composite joints. Full article

Mechanical models are capable of simulating the deformation and stress distribution of oocytes under external forces, thereby providing insights into the underlying mechanisms of intracellular mechanical responses. Interactions with micromanipulation tools involve forces like compression and punction, which are effectively analyzed using principles of solid mechanics. Alternatively, fluid–structure interactions, such as shear stress at fluid junctions or pressure gradients within microchannels, are best described by a multiphase flow model. Developing the two models instead of a single comprehensive model is necessary due to the distinct nature of cell–tool interactions and cell–fluid interactions. In this study, we developed a finite element (FE) model of porcine oocytes that accounts for the viscoelastic properties of the zona pellucida (ZP) and cytoplasm for the case when the oocytes interacted with a micromanipulation tool. Atomic force microscopy (AFM) was employed to measure the Young’s modulus and creep behavior of these subcellular components that were incorporated into the FE model. When the oocyte was solely interacting with the fluids, we simulated oocyte deformation in microfluidic channels by modeling the oocyte-culture-medium system as a three-phase flow, considering the non-Newtonian behavior of the oocyte’s components. Our results show that the Young’s modulus of the ZP and cytoplasm were determined to be 7 kPa and 1.55 kPa, respectively, highlighting the differences in the mechanical properties between these subcomponents. Using the developed layered FE model, we accurately simulated oocyte deformation during their passage through a narrow-necked micropipette, with a deformation error of approximately 5.2% compared to experimental results. Using the three-phase flow model, we effectively simulated oocyte deformation in microfluidic channels under various pressures, validating the model’s efficacy through close agreement with experimental observations. This work significantly contributes to assessing oocyte quality and serves as a valuable tool for advancing cell mechanics studies. Full article

This research investigates the physical and mechanical properties of Codonopsis pilosula seedlings to provide fundamental mechanical data to address issues like high damage rates and low efficiency in mechanized transplanting. After precise physical parameter measurements, we classified the seedlings into four types: l-type, Y-type, V-type, and W-type. The l-type was the most common, accounting for a large proportion (80.95%) of the total, with a median length of approximately 270 mm, a median diameter of around 5.0 mm, and an average individual weight of about 2.83 g. Freshly harvested seedlings had an average moisture content and density within the typical range for this species. Using the Box–Behnken design method, we determined that the primary and secondary factors affecting tensile force (F_N) and tensile strength (σ) were sample diameter (D), sample length (L), and loading speed (V). Sample diameter had a significant impact: F_N increased rapidly as the diameter grew, while tensile strength (σ) decreased. The tensile strength of different regions of the seedling (i.e., head, middle, and tail) showed distinct characteristics, with relatively small deviations between theoretical and experimental values. For the whole seedling, errors in tensile force (F_N) and strength (σ) between measured and theoretical values were below 5%. The average Young’s modulus, Poisson’s ratio, and shear modulus were also calculated. These mechanical property indices thus provide crucial references for future related research. Full article

This study investigates the effect of tensile strain during high-temperature carbonization on the microstructural development and mechanical properties of polyacrylonitrile (PAN)-based carbon fibers. The wet-spun stabilized PAN precursor fibers were carbonized at 1400 °C under various tensile draw ratios (0%, 5%, 10%, and 15%), followed by stress-free graphitization at 2400 °C in an argon atmosphere for 1 h to isolate the effects of the carbonization-stage tension. Structural characterization using XRD, 2D-XRD, Raman spectroscopy, and HR-TEM revealed that moderate tensile strain (5–10%) promoted significant improvements in crystallinity, orientation, and graphene layer alignment. Notably, the fiber drawn at 10% performed the best, with a reduced interlayer spacing (d₀₀₂), increased lateral crystallite size (L_a), high orientation factor, and minimal turbostratic disorder. These structural developments translated into the best mechanical properties, including a tensile strength of ~2.44 GPa, a Young’s modulus of ~408.6 GPa, and the highest measured density (1.831 g/cm³). In contrast, excessive strain (15%) induced microstructural defects and reduced performance, underscoring the detrimental effects of overstretching. The findings highlight the critical role of draw control during carbonization in optimizing the structure–property relationships of carbon fibers, offering valuable insight for the design of high-performance fiber processing strategies. Full article

This study concerns the evaluation of adhesive and wettability energetic signatures of a model orthodontic wire exposed to commercial mouthrinses. The surface wetting properties were evaluated from the contact angle hysteresis (CAH) approach applied to dynamic contact angle data derived from the original drop on a vertical filament method. Young, advancing, receding CA apart from adhesive film pressure, surface energy, work of adhesion, etc. were chosen as interfacial interaction indicators, allowing for the optimal concentration and placement of the key component(s) accumulation to be predicted for effective antibacterial activity to eliminate plaque formation on the prosthetic materials. Surfactant compounds when adsorb at interfaces confer rheological properties to the surfaces, leading to surface relaxation, which depends on the timescale of the deformation. The surface dilatational complex modulus E, with compression elasticity E_d and viscosity E_i parts, determined in the stress–relaxation Langmuir trough measurements, exhibited the viscoelastic surface film behavior with the relaxation times (0.41–3.13 s), pointing to the vertically segregated film structure as distinct, stratified layers with the most insoluble compound on the system top (as indicated with the 2D polymer film scaling theory exponent y = 12.9–15.5). Kinetic rheology parameters could affect the wettability, adhesion, and spreading characteristics of mouthrinse liquids. Full article