International Journal of Clinical and Biomedical Sciences

Background: Polyamide 6 (PA6) is a widely used engineering thermoplastic known for its excellent mechanical properties, thermal stability, and wear resistance. However, its semi-crystalline structure and low thermal conductivity present significant challenges during machining operations, particularly in achieving optimal surface finish. Surface roughness is a critical quality indicator that affects the functional performance, fatigue life, and aesthetic appearance of machined polymer components. Understanding the complex interactions between machining parameters and environmental conditions is essential for optimizing the turning process of PA6. Objective: This comprehensive review investigates the influence of machining parameters—cutting velocity (Vc), feed rate (FR), and depth of cut (Dc)—and machining environments—dry (D), compressed air (A), and air-water mixture (A+W)—on the surface roughness (Ra) of Polyamide 6 during turning operations. The study aims to identify the most influential parameters, quantify their percentage contributions, and determine the optimal combination for achieving minimum surface roughness. Methods: A systematic experimental approach was combined with statistical analysis using Taguchi Experiment Design (TED) and Analysis of Variance (ANOVA). Experiments were conducted on a CU-500 lathe using a carbide cutting tool (Mitsubishi CNMG 120408 UE6020) with a PCLNR 2525 M12 tool holder. PA6 samples of 40 mm diameter and 500 mm length were machined at three levels for each parameter: cutting velocity (125, 200, 250 m/min), feed rate (0.05, 0.1, 0.15 mm/rev), depth of cut (2, 4, 6 mm), and three machining environments. Surface roughness was measured using an SRT5000 roughness tester. The Taguchi L9 orthogonal array was employed to design experiments efficiently, and the signal-to-noise ratio (SNR) with "smaller-is-better" criterion was used for optimization. ANOVA quantified the percentage contribution of each parameter. Results: The experimental results demonstrate that feed rate is the most dominant factor affecting surface roughness, contributing 61% of the total effect. Machining environment contributes 15%, depth of cut 13%, and cutting velocity 11%. Lower feed rates (0.05 mm/rev) consistently produced superior surface finishes (Ra = 1.2 μm), while higher feed rates (0.15 mm/rev) resulted in rougher surfaces (Ra = 2.5 μm). The air-water mixture environment significantly improved surface quality compared to dry and compressed air conditions due to enhanced cooling and lubrication effects. Lower cutting velocities (125-200 m/min) and shallower depths of cut (2 mm) also contributed to better surface finishes by reducing cutting forces, vibration, and thermal deformation. The optimal combination for minimum surface roughness was identified as: cutting velocity of 125 m/min, feed rate of 0.05 mm/rev, depth of cut of 2 mm, and air-water mixture environment, achieving a minimum Ra of 1.2 μm. Conclusion: This comprehensive investigation establishes that feed rate is the primary control parameter for achieving high-quality surface finishes in PA6 turning operations. The air-water mixture environment provides significant improvements in surface quality through effective cooling and lubrication. The study provides manufacturers with evidence-based guidelines for selecting optimal machining parameters to enhance product quality, reduce costs, and extend tool life. The findings contribute to the broader understanding of polymer machining and offer a foundation for developing predictive models and process optimization strategies.

Background: Polyamide 6 (PA6) is a widely used engineering thermoplastic known for its excellent mechanical properties, thermal stability, and wear resistance. However, its semi-crystalline structure and low thermal conductivity present significant challenges during machining operations, particularly in achieving optimal surface finish. Surface roughness is a critical quality indicator that affects the functional performance, fatigue life, and aesthetic appearance of machined polymer components. Understanding the complex interactions between machining parameters and environmental conditions is essential for optimizing the turning process of PA6. Objective: This comprehensive review investigates the influence of machining parameters—cutting velocity (Vc), feed rate (FR), and depth of cut (Dc)—and machining environments—dry (D), compressed air (A), and air-water mixture (A+W)—on the surface roughness (Ra) of Polyamide 6 during turning operations. The study aims to identify the most influential parameters, quantify their percentage contributions, and determine the optimal combination for achieving minimum surface roughness. Methods: A systematic experimental approach was combined with statistical analysis using Taguchi Experiment Design (TED) and Analysis of Variance (ANOVA). Experiments were conducted on a CU-500 lathe using a carbide cutting tool (Mitsubishi CNMG 120408 UE6020) with a PCLNR 2525 M12 tool holder. PA6 samples of 40 mm diameter and 500 mm length were machined at three levels for each parameter: cutting velocity (125, 200, 250 m/min), feed rate (0.05, 0.1, 0.15 mm/rev), depth of cut (2, 4, 6 mm), and three machining environments. Surface roughness was measured using an SRT5000 roughness tester. The Taguchi L9 orthogonal array was employed to design experiments efficiently, and the signal-to-noise ratio (SNR) with "smaller-is-better" criterion was used for optimization. ANOVA quantified the percentage contribution of each parameter. Results: The experimental results demonstrate that feed rate is the most dominant factor affecting surface roughness, contributing 61% of the total effect. Machining environment contributes 15%, depth of cut 13%, and cutting velocity 11%. Lower feed rates (0.05 mm/rev) consistently produced superior surface finishes (Ra = 1.2 μm), while higher feed rates (0.15 mm/rev) resulted in rougher surfaces (Ra = 2.5 μm). The air-water mixture environment significantly improved surface quality compared to dry and compressed air conditions due to enhanced cooling and lubrication effects. Lower cutting velocities (125-200 m/min) and shallower depths of cut (2 mm) also contributed to better surface finishes by reducing cutting forces, vibration, and thermal deformation. The optimal combination for minimum surface roughness was identified as: cutting velocity of 125 m/min, feed rate of 0.05 mm/rev, depth of cut of 2 mm, and air-water mixture environment, achieving a minimum Ra of 1.2 μm. Conclusion: This comprehensive investigation establishes that feed rate is the primary control parameter for achieving high-quality surface finishes in PA6 turning operations. The air-water mixture environment provides significant improvements in surface quality through effective cooling and lubrication. The study provides manufacturers with evidence-based guidelines for selecting optimal machining parameters to enhance product quality, reduce costs, and extend tool life. The findings contribute to the broader understanding of polymer machining and offer a foundation for developing predictive models and process optimization strategies.

COVID-19, caused by SARS-CoV-2, affects multiple organ systems beyond the lungs, including the endocrine system. Recent studies suggest that the adrenal glands and the hypothalamic–pituitary–adrenal (HPA) axis may be disrupted during infection, leading to altered cortisol regulation. This review examines the mechanisms through which SARS-CoV-2 influences adrenal function and cortisol secretion. A systematic literature review was conducted using PubMed, Scopus, Web of Science, and Embase databases for studies published between 2020 and 2024. The review focused on research addressing adrenal gland involvement, cortisol regulation, glucocorticoid receptor function, and HPA axis alterations in COVID-19 patients. Evidence indicates that SARS-CoV-2 may directly affect adrenal tissue through ACE2 and TMPRSS2 receptors. Adrenal dysfunction may occur through several mechanisms, including viral cytopathic effects, inflammation during cytokine storm, molecular mimicry affecting ACTH, and glucocorticoid receptor resistance. These processes can lead to conditions such as adrenal insufficiency and critical illness-related corticosteroid insufficiency (CIRCI). Some recovered patients also show temporary hypocortisolism due to central HPA axis disruption. Overall, SARS-CoV-2 infection can significantly influence cortisol regulation and adrenal function. Awareness of these endocrine complications is important for clinical management and long-term monitoring of post-COVID-19 patients.

Cutaneous carcinosarcoma is a rare biphasic skin malignancy composed of both epithelial and mesenchymal cancerous components. Due to its rarity and complex morphology, it often poses diagnostic challenges and may be mistaken for more common skin tumors. This report presents the case of an 87-year-old male with a three-month history of a progressively ulcerated lesion on the left posterior scalp. Clinical examination suggested squamous cell carcinoma, and the lesion was treated with wide local excision. Histopathological analysis revealed a tumor measuring 8.2 mm in thickness with invasion into the reticular dermis and focal extension into subcutaneous tissue (pT3). Microscopic examination identified two malignant components: basal cell carcinoma and a high-grade pleomorphic spindle-cell sarcomatous component. Immunohistochemical staining showed positivity for cytokeratins, S100, p63, CD68, and vimentin, confirming the biphasic nature of the tumor and supporting the diagnosis of cutaneous carcinosarcoma arising from basal cell carcinoma. Surgical excision with margins greater than 6 mm was achieved, and the patient remains under close follow-up. This case highlights the importance of accurate histopathological and immunohistochemical evaluation in diagnosing cutaneous carcinosarcoma, as the tumor shows more aggressive behavior than conventional skin cancers and requires careful surgical management and long-term surveillance.

Cholecystectomy is a common surgical procedure used to treat gallstone disease. Since the introduction of laparoscopic cholecystectomy, minimally invasive techniques have largely replaced traditional open surgery due to improved clinical outcomes. This study reviews the comparative outcomes of laparoscopic and open cholecystectomy with a focus on quality of life, social support, and clinical recovery. A systematic literature review of studies published between 2010 and 2025 was conducted using databases including PubMed, Scopus, Web of Science, and the Cochrane Library. In addition, primary data from 96 patients who underwent cholecystectomy were analyzed using the WHOQOL-BREF quality of life questionnaire and the Multidimensional Scale of Perceived Social Support (MSPSS). Results indicate that laparoscopic cholecystectomy provides significant advantages, including reduced postoperative pain, shorter hospital stays, quicker recovery, and fewer complications compared to open surgery. Quality of life scores showed significant improvement after surgery across physical, psychological, social, and environmental domains. Social support levels also increased significantly after surgery, regardless of the surgical approach. The findings suggest that laparoscopic cholecystectomy is the preferred treatment for symptomatic gallstone disease due to its better recovery outcomes and improved patient well-being.