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Bone tissue engineering shows potential for regenerating or replacing damaged bone tissues by utilizing biomaterials renowned for their biocompatibility and structural support capabilities. Among these biomaterials, polycaprolactone (PCL) and polylactic acid (PLA) have gained attention due to their biodegradability and versatile applications. However, challenges such as low degradation rates and poor mechanical properties limit their effectiveness. Dimethyl sulfone (DMSO2) has emerged as a potential additive to address these limitations, offering benefits such as reduced viscosity, increased degradation time, and enhanced surface tension. In this study, we investigate tailored composites comprising PLA, PCL, and DMSO2 to enhance mechanical properties and hydrophilicity. Through material characterization and mechanical testing, we found that the addition of DMSO2 led to improvements in the yield strength, modulus, and hydrophilicity of the composites. PCL and DMSO2 10, 20, and 30 wt% were premixed, and 20 wt% PCL + 10, 20, and 30 wt% DMSO2 were mixed with PLA. Specifically, PLA/PCL/DMSO2 composites exhibited higher yield strengths and moduli compared to pure PLA, pure PCL, and PLA/PCL composites. Moreover, the hydrophilicity of the composites increased with DMSO2 concentration, facilitating cell attachment. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of –COOH and –COH bands in PLA/PCL/DMSO2 composites, indicating chemical interactions between DMSO2 and the polymer matrix. Fractography analysis revealed enhanced interface adhesion in PLA/PCL/DMSO2 composites due to the hydrogen bonding. Overall, this study demonstrates the potential of PLA/PCL/DMSO2 composites in bone tissue engineering applications, offering improved mechanical properties and enhanced cell compatibility. The findings contribute to the advancement of biomaterials for additive manufacturing in tissue engineering and regenerative medicine. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of utilizing the finite element method (FEM)-based conductive heat transfer (CHT) analysis simulation to determine temperature gradients and solidification rates at the solid–liquid interface during laser beam oscillation welding. By comparing experimental observations with FEM-based CHT analysis, the underlying microstructural evolution and grain formation during welding were examined. FEM-based CHT enables the calculation of temperature gradients (G) and solidification rates (R), offering insights into the formation of equiaxed structures, which are crucial for suppressing hot cracking. Columnar-to-equiaxed structure transition thresholds, such as G/R and G3/R, accurately predict the emergence of fully equiaxed grain structures, validated by electron backscatter diffraction. This research provides valuable insights into temperature gradients and solidification rates in oscillation welding, guiding process design for achieving refined equiaxed structures and minimizing hot cracks. [ABSTRACT FROM AUTHOR]

This study aimed to develop an artificial neural network (ANN) model for predicting the yield strength of a weld metal composed of austenitic stainless steel and compare its performance with that of conventional multiple regression and machine learning models. The input parameters included the chemical composition of the nine effective elements (C, Si, Mn, P, S, Ni, Cr, Mo, and Cu) and the heat input per unit length. The ANN model (comprising five nodes in one hidden layer), which was constructed and trained using 60 data points, yielded an R2 value of 0.94 and a mean average percent error (MAPE) of 2.29%. During model verification, the ANN model exhibited superior prediction performance compared with the multiple regression and machine learning models, achieving an R2 value of 0.8644 and a MAPE of 3.06%. Consequently, the ANN model effectively predicted the variation in the yield strength and microstructure resulting from the thermal history and dilution during the welding of 3.5–9% Ni steels with stainless steel-based welding consumables. Furthermore, the application of the prediction model was demonstrated in the design of welding consumables and heat input for 9% Ni steel. [ABSTRACT FROM AUTHOR]

The significance of rheology in the context of bio three-dimensional (3D) printing lies in its impact on the printing behavior, which shapes material flow and the layer-by-layer stacking process. The objective of this study is to evaluate the rheological and printing behaviors of polycaprolactone (PCL) and dimethyl sulfone (DMSO2) composites. The rheological properties were examined using a rotational rheometer, employing a frequency sweep test. Simultaneously, the printing behavior was investigated using a material extrusion 3D printer, encompassing varying printing temperatures and pressures. Across the temperature range of 120–140 °C, both PCL and PCL/DMSO2 composites demonstrated liquid-like behavior, with a higher loss modulus than storage modulus. This behavior exhibited shear-thinning characteristics. The addition of DMSO2 10, 20, and 30 wt% into the PCL matrix reduced a zero-shear viscosity of 33, 46, and 74% compared to PCL, respectively. The materials exhibited extrusion velocities spanning from 0.0850 to 6.58 mm/s, with velocity being governed by the reciprocal of viscosity. A significant alteration in viscosity by temperature change directly led to a pronounced fluctuation in extrusion velocity. Extrusion velocities below 0.21 mm/s led to the production of unstable printed lines. The presence of distinct viscosities altered extrusion velocity, flow rate, and strut diameter. This phenomenon allowed the categorization of pore shape into three zones: irregular, normal, and no-pore zones. It underscored the importance of comprehending the rheological aspects of biomaterials in enhancing the overall quality of bio-scaffolds during the 3D printing process. [ABSTRACT FROM AUTHOR]

Solidification cracking, one of the most critical weld defects in laser welding of Al 6000 alloys, occurs at the final stage of solidification owing to shrinkage of the weld metal and deteriorates the joint strength and integrity. The filler metal can control the chemical composition of the weld metal, which mitigates solidification cracking. However, the chemical composition is difficult to control in autogenous laser welding. Temporal and spatial laser beam modulations have been introduced to control solidification cracking in autogenous laser welding because weld morphology is one of the factors that influences the initiation and propagation of solidification cracking. Solidification cracks generate thermal discontinuities and visual flaws on the bead surface. In this study, a high-speed infrared camera and a coaxial charge-coupled device camera with an auxiliary illumination laser (808 nm) were employed to identify solidification cracking during laser welding. Deep learning models, developed using two sensor images of a solidified bead, provided location-wise crack formation information. The multisensor-based convolutional neural network models achieved an impressive accuracy of 99.31% in predicting the crack locations. Thus, applying deep learning models expands the capability of predicting solidification cracking, including previously undetectable internal cracks. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL) has been one of the most popular biomaterials in tissue engineering due to its relatively low melting temperature, excellent thermal stability, and cost-effectiveness. However, its low cell attraction, low elastic modulus, and long-term degradation time have limited its application in a wide range of scaffold studies. Dimethyl sulfone (DMSO2) is a stable and non-hazardous organosulfur compound with low viscosity and high surface tension. PCL and DMSO2 composites may overcome the limitations of PCL as a biomaterial and tailor the properties of biocomposites. In this study, PCL and DMSO2 composites were investigated as a new bio-scaffold material to increase hydrophilicity and mechanical properties and tailor degradation properties in vitro. PCL and DMSO2 were physically mixed with 10, 20, and 30 wt% of DMSO2 to evaluate thermal, hydrophilicity, mechanical, and degradation properties of the composites. The water contact angle of the composites for hydrophilicity decreased by 15.5% compared to pure PCL. The experimental results showed that the mechanical and degradation properties of PCL and DMSO2 were better than those of pure PCL, and the properties can be tuned by regulating DMSO2 concentration in the PCL matrix. The elastic modulus of the composite with 30 wt% of DMSO2 showed 532 MPa, and its degradation time was 18 times faster than that of PCL. [ABSTRACT FROM AUTHOR]