Microstructural and mechanical properties of welded Ti-15-3 beta titanium alloy using gtaw with boron-modified fillers / Ahmad Lutfi Anis

Mechanical properties of titanium alloys are dictated by their microstructure, particularly the size, shape and distribution of hexagonally close-packed (hcp) α and body-centred cubic (bcc) β phases. For metastable β titanium alloys the morphology and distribution of α precipitates have largely contributed to its mechanical properties. Welded zones in gas tungsten arc welding (GTAW) of metastable β titanium alloys exhibit retained β structure with inferior mechanical properties due to coarse columnar prior β grains and lack of α precipitates in the matrix in as-welded condition. In this work refinement of prior β grains and α was achieved in GTAW welds of metastable β titanium alloy, Ti-15V-3Cr-3Al-3Sn (Ti-15-3) by current pulsing and modification of welding fillers. Autogenous pulsed current GTAW were performed at 0, 2, 4 and 6 Hz pulsing frequencies to determine optimum frequency for pulsed current welding of thin plates Ti-15-3 alloy. Welding of Ti-15-3 alloy using commercially pure α titanium (CP-Ti) alloy filler resulted in the precipitation of α phase from β phase during cooling to ambient temperature due to dilution of melted base metal with the filler metal. The GTAW welds with CP-Ti filler exhibit high hardness, higher tensile strength but lower % strain as compared to the autogenous weld owing to precipitation of α phase precipitation at β grain boundaries. Addition of 0.5 wt.% and 1.0 wt.% boron to CP-Ti fillers resulted in significantly refined fusion zone β grains in welds with CP-Ti-0.5B and CP-Ti-1.0B fillers due to growth restriction mechanism associated with partitioning of boron during solidification. X-ray diffraction (XRD) analysis of autogenous welds showed only bcc β-Ti phase while indexed peaks for the weld samples with CP-Ti filler showed the presence of very small hcp α-Ti phase along with bcc β-Ti phase. Welds with CP-Ti- 0.5B and CP-Ti-1.0B fillers showed additional orthorhombic TiB peaks. Mechanical tests show that hardness of the fusion zone and tensile strength in welds with boron-added CP-Ti fillers are higher than that in autogenous welds and welds with CP-Ti filler. Post-weld heat treatment (PWHT) of the welded samples increased α precipitation in all samples while FESEM and TEM analysis of the fusion zones showed α with higher aspect ratios in aged welds with boron-added CP-Ti fillers than autogenous weld and weld with CP-Ti filler, attributed to the additional nucleation sites provided by increase in boundary area of refined prior β grains with the addition of boron. PWHT weldments displayed higher hardness values, compared to similar regions in as-welded samples, and higher tensile strength after aging

Microstructural and mechanical properties of welded Ti-15-3 beta titanium alloy using GTAW with boron-modified fillers / Ahmad Lutfi Anis

Mechanical properties of titanium alloys are dictated by their microstructure, particularly the size, shape and distribution of hexagonally close-packed (hcp) α and body-centred cubic (bcc) β phases. For metastable β titanium alloys the morphology and distribution of α precipitates have largely contributed to its mechanical properties. Welded zones in gas tungsten arc welding (GTAW) of metastable β titanium alloys exhibit retained β structure with inferior mechanical properties due to coarse columnar prior β grains and lack of α precipitates in the matrix in as-welded condition. In this work refinement of prior β grains and α. was achieved in GTAW welds of metastable β titanium alloy, Ti-15V-3Cr-3Al-3Sn (Ti-15-3) by current pulsing and modification of welding fillers. Autogenous pulsed current GTAW were performed at 0, 2, 4 and 6 Hz pulsing frequencies to determine optimum frequency for pulsed current welding of thin plates Ti-15-3 alloy. Welding of Ti-15-3 alloy using commercially pure α titanium (CPTi) alloy filler resulted in the precipitation of α phase from β phase during cooling to ambient temperature due to dilution of melted base metal with the filler metal. The GTAW welds with CP-Ti filler exhibit high hardness, higher tensile strength but lower % strain as compared to the autogenous weld owing to precipitation of a phase precipitation at β grain boundaries. Addition of 0.5 wt.% and 1.0 wt.% boron to CP-Ti fillers resulted in significantly refined fusion zone β grains in welds with CP-Ti-0.5B and CP-Ti-1 .0B fillers due to growth restriction mechanism associated with partitioning of boron during solidification. X-ray diffraction (XRD) analysis of autogenous welds showed only bcc β-Ti phase while indexed peaks for the weld samples with CP-Ti filler showed the presence of very small hcp α-Ti phase along with bcc β-Ti phase. Welds with CP-Ti-0.5B and CP-Ti-1.0B fillers showed additional orthorhombic TiB peaks. Mechanical tests show that hardness of the fusion zone and tensile strength in welds with boron-added CP-Ti fillers are higher than that in autogenous welds and welds with CP-Ti filler. Post-weld heat treatment (PWHT) of the welded samples increased α precipitation in all samples while FESEM and TEM analysis of the fusion zones showed α with higher aspect ratios in aged welds with boron-added CP-Ti fillers than autogenous weld and weld with CP-Ti filler, attributed to the additional nucleation sites provided by increase in boundary area of refined prior β grains with the addition of boron. PWHT weldments displayed higher hardness values, compared to similar regions in as-welded samples, and higher tensile strength after aging

Effectiveness of Online Training for Rural Entrepreneurs During a Global Pandemic

The ability of rural entrepreneurs to cope with the COVID-19 pandemic greatly depends on their knowledge of Information and Communication Technology (ICT) to support online business. In this study, online surveys were conducted to assess the readiness and acceptance of rural entrepreneurs in adopting to the pandemic using the available technologies. Data collected were analyzed by descriptive and inferential statistics using ANOVA. Online training modules were designed based on their specific needs. Although participants indicated that their frequency and skills of using the electronic devices or applications had generally increased or improved after the training, the increment was not statistically significant (α=0.05). This indicated that while the participants, to some extent, benefited from the online training provided, there has not been a significant impact on them

Integrative healthcare approaches for children with special needs: a holistic study on challenges and solutions

This study delves into the intricate healthcare landscape for children with special needs, shedding light on the multifarious challenges these individuals face and evaluating the effectiveness of integrative healthcare models tailored to their unique requirements. Conducted at Sekolah Kebangsaan Pendidikan Khas Kuantan, this cross-sectional qualitative analysis involved detailed surveys with 20 teachers and engaging discussions with 24 students, aiming to unravel the complexities of providing holistic care to this vulnerable population. The investigation meticulously identifies pivotal concerns such as the prevalence of behavioral issues, particularly in autistic children, who often exhibit aggressive and self-injurious behaviors, and the struggles encountered by hearing-impaired students in communication and learning. It further explores the susceptibility of these children to frequent infections due to immune system dysfunction, exacerbated by dietary imbalances and physical inactivity. The research emphasizes the indispensable role of early detection and intervention in mitigating health risks and outlines the significance of specialized supplements, medications, and rigorous oral hygiene practices in maintaining the overall well-being of these children. Additionally, the study brings to the forefront the critical impact of socioeconomic factors on healthcare access, advocating for equitable healthcare solutions. It also highlights the transformative potential of technology, including telehealth and assistive devices, in overcoming barriers to healthcare and education. Through this analysis, the study advocates for a comprehensive, integrative care approach that encompasses medical, educational, social, and psychological services, underscoring the necessity of collaborative efforts among healthcare providers, educators, and families to significantly enhance the quality of life and well-being of children with special needs

Stoma-free survival after anastomotic leak following rectal cancer resection: worldwide cohort of 2470 patients

Background: The optimal treatment of anastomotic leak after rectal cancer resection is unclear. This worldwide cohort study aimed to provide an overview of four treatment strategies applied. Methods: Patients from 216 centres and 45 countries with anastomotic leak after rectal cancer resection between 2014 and 2018 were included. Treatment was categorized as salvage surgery, faecal diversion with passive or active (vacuum) drainage, and no primary/secondary faecal diversion. The primary outcome was 1-year stoma-free survival. In addition, passive and active drainage were compared using propensity score matching (2: 1). Results: Of 2470 evaluable patients, 388 (16.0 per cent) underwent salvage surgery, 1524 (62.0 per cent) passive drainage, 278 (11.0 per cent) active drainage, and 280 (11.0 per cent) had no faecal diversion. One-year stoma-free survival rates were 13.7, 48.3, 48.2, and 65.4 per cent respectively. Propensity score matching resulted in 556 patients with passive and 278 with active drainage. There was no statistically significant difference between these groups in 1-year stoma-free survival (OR 0.95, 95 per cent c.i. 0.66 to 1.33), with a risk difference of -1.1 (95 per cent c.i. -9.0 to 7.0) per cent. After active drainage, more patients required secondary salvage surgery (OR 2.32, 1.49 to 3.59), prolonged hospital admission (an additional 6 (95 per cent c.i. 2 to 10) days), and ICU admission (OR 1.41, 1.02 to 1.94). Mean duration of leak healing did not differ significantly (an additional 12 (-28 to 52) days). Conclusion: Primary salvage surgery or omission of faecal diversion likely correspond to the most severe and least severe leaks respectively. In patients with diverted leaks, stoma-free survival did not differ statistically between passive and active drainage, although the increased risk of secondary salvage surgery and ICU admission suggests residual confounding

Stoma-free Survival After Rectal Cancer Resection With Anastomotic Leakage: Development and Validation of a Prediction Model in a Large International Cohort.

Objective:To develop and validate a prediction model (STOMA score) for 1-year stoma-free survival in patients with rectal cancer (RC) with anastomotic leakage (AL).Background:AL after RC resection often results in a permanent stoma.Methods:This international retrospective cohort study (TENTACLE-Rectum) encompassed 216 participating centres and included patients who developed AL after RC surgery between 2014 and 2018. Clinically relevant predictors for 1-year stoma-free survival were included in uni and multivariable logistic regression models. The STOMA score was developed and internally validated in a cohort of patients operated between 2014 and 2017, with subsequent temporal validation in a 2018 cohort. The discriminative power and calibration of the models' performance were evaluated.Results:This study included 2499 patients with AL, 1954 in the development cohort and 545 in the validation cohort. Baseline characteristics were comparable. One-year stoma-free survival was 45.0% in the development cohort and 43.7% in the validation cohort. The following predictors were included in the STOMA score: sex, age, American Society of Anestesiologist classification, body mass index, clinical M-disease, neoadjuvant therapy, abdominal and transanal approach, primary defunctioning stoma, multivisceral resection, clinical setting in which AL was diagnosed, postoperative day of AL diagnosis, abdominal contamination, anastomotic defect circumference, bowel wall ischemia, anastomotic fistula, retraction, and reactivation leakage. The STOMA score showed good discrimination and calibration (c-index: 0.71, 95% CI: 0.66-0.76).Conclusions:The STOMA score consists of 18 clinically relevant factors and estimates the individual risk for 1-year stoma-free survival in patients with AL after RC surgery, which may improve patient counseling and give guidance when analyzing the efficacy of different treatment strategies in future studies