Improving the Surface Integrity of 316L Steel in the Context of Bioimplant Applications

Comparison of pre- and post-implantation of Indonesian-made plates in fracture patients: Functional, radiological, biomechanical and chemical analyses

Bone implants are important in the recovery of fractures and degenerative diseases. Although many implants have been marketed, study on Indonesian-made plates is still limited. The aim of this study was to assess the patients' functional and radiological improvements and biomechanical and chemical changes of Indonesian-made plates used in long bone fractures. retrospective study was conducted at Semen Gresik Hospital, Gresik, Indonesia. This study included adult patients with long bone fractures who had surgeries with Indonesian plates. Functional improvement (assessed using disabilities of arm, shoulder, and hand (DASH) or lower extremity functional scale (LEFS)) and radiological data (assessed using radiographic union score (RUS)) were assessed in week 4 and month 6, 12, and 15 after surgery. Biomechanical changes (hardness and roughness test) and chemical analysis were assessed after 15 months of use. The normality of the data was tested with Shapiro-Wilk while data analysis was conducted using paired Student t-test or Friedman test as appropriate with type of data. Our data indicated that the DASH and LEFS functional scores had significant improvement over the follow-ups indicating functional recovery. RUS scores also improved over time, indicating a good healing process. Hardness tests on post-surgery implants showed a decrease in hardness of 7.3% and an increase of 3.3% in roughness. Chemical analysis showed a reduction in chemical levels in the implant of 7.8%, indicating durability and minimal toxicity. This study highlights that Indonesian implants have been proven safe to use in fractures. Further examinations with a larger sample and a longer duration of monitoring are recommended for stronger validity.

SliceChip: a benchtop fluidic platform for organotypic culture and serial assessment of human and rodent pancreatic slices

Enzymatically isolated pancreatic islets are the most commonly used ex vivo testbeds for diabetes research. Recently, precision-cut living slices of human pancreas are emerging as an exciting alternative because they maintain the complex architecture of the endocrine and exocrine tissues, and do not suffer from the mechanical and chemical stress of enzymatic isolation. We report a fluidic pancreatic SliceChip platform with dynamic environmental controls that generates a warm, oxygenated, and bubble-free fluidic pathway across singular immobilized slices with continuous deliver of fresh media and the ability to perform repeat serial perfusion assessments. A degasser ensures the system remains bubble-free while systemic pressurization with compressed oxygen ensures slice medium remains adequately oxygenated. Computational modeling of perfusion and oxygen dynamics within SliceChip guide the system's physiomimetic culture conditions. Maintenance of the physiological glucose dependent insulin secretion profile across repeat perfusion assessments of individual pancreatic slices kept under physiological oxygen levels demonstrated the culture capacity of our platform. Fluorescent images acquired every 4 hours of transgenic murine pancreatic slices were reliably stable and recoverable over a 5 day period due to the inclusion of a 3D-printed bioinert metallic anchor that maintained slice position within the SliceChip. Our slice on a chip platform has the potential to expand the useability of human pancreatic slices for diabetes pathogenesis and the development of new therapeutic approaches, while also enabling organotypic culture and assessment of other tissue slices such as brain and patient tumors.

Optimization Milling Force and Surface Roughness of Ti-6Al-4V Based on Ultrasonic-Assisted Milling (UAM): An Experimental Study

This study aimed to develop a longitudinal ultrasonic-assisted milling system to investigate the machinability of titanium (Ti) Alloy Ti-6Al-4V (TC4). Aiming at reduced milling force and enhanced surface quality, ultrasonic-assisted milling was investigated taking into account the following processing parameters: spindle speed (cutting rate) n, feed per tooth fz, milling depth ap, and ultrasonic amplitude A. A comparison was made with conventional milling. The results of univariate tests demonstrated that the ultrasonic amplitude had the most significant impact on the milling force along the z-axis, resulting in a reduction of 15.48% compared with conventional milling. The range analysis results of multivariate tests demonstrated that ap and fz were the dominant factors influencing the cutting force. The minimum reduction in the milling force in ultrasonic-assisted milling along the x-, y-, and z-axes was 11.77%, 15.52%, and 17.66%, respectively, compared with that in conventional milling. The ultrasonic-assisted milling led to reduced surface roughness and enhanced surface quality; the maximum surface roughness in ultrasonic-assisted milling was 25.93%, 36.36% and 26.32% in terms of n, fz, and ap, respectively. In longitudinal ultrasonic-assisted milling, the periodic "separation-contact" was accompanied by microimpacts, resulting in even smaller intermittent periodic cutting forces. Hence, regular fish scale machining mesh was observed on the processed surface, and the workpiece surface exhibited high cleanness and smoothness. The reasonable configuration of ultrasonic-assisted milling parameters can effectively improve the milling force and surface quality of Ti alloys and accumulate reference data for the subsequent machining process research.

Comparison of Tool Wear, Surface Roughness, Cutting Forces, Tool Tip Temperature, and Chip Shape during Sustainable Turning of Bearing Steel

In this study, a comparison of measured cutting parameters is discussed while machining AISI 52100 low-alloy hardened steel under two different sustainable cutting environments, those in which a dry and minimum quantity lubrication (MQL) medium are used. A two-level full factorial design method has been utilized to specify the effect of different experimental inputs on the turning trials. Experiments were carried out to investigate the effects of three basic defining parameters of turning operation which are namely cutting speed, cutting depth, feed rate effects and also the effects of the cutting environment. The trials were repeated for the combination of different cutting input parameters. The scanning electron microscopy imaging method was used to characterize the tool wear phenomenon. The macro-morphology of chips was analyzed to define the influence of cutting conditions. The optimum cutting condition for high-strength AISI 52100 bearing steel was obtained using the MQL medium. The results were evaluated with graphical representations and they indicated the superiority of the pulverized oil particles on tribological performance of the cutting process with application of the MQL system.