On the Development of Smart Framework for Printability Maps in Additive Manufacturing of AISI 316L Stainless Steel.

In this work, we propose a methodology to develop printability maps for the laser powder bed fusion of AISI 316L stainless steel. Regions in the process space associated with different defect types, including lack of fusion, balling, and keyhole formation, have been considered as a melt pool geometry function, determined using a finite element method model containing temperature-dependent thermophysical properties. Experiments were performed to validate the printability maps, showing a reliable correlation between experiments and simulations. The validated simulation model was then applied to collect the data by varying laser scanning speed, laser power, powder layer thickness, and powder bed preheating temperature. Following this, the collected data were used to train and test the adaptive neuro-fuzzy interference system (ANFIS)-based machine learning model. The validated ANFIS model was used to develop printability maps by correlating the melt pool characteristics to the defect types. The smart printability maps produced by the proposed methodology can be used to identify the processing window to attain defects-free components, thus attaining dense parts.

Rare homozygous cilia gene variants identified in consanguineous congenital heart disease patients.

Congenital heart defects (CHD) appear in almost one percent of live births. Asian countries have the highest birth prevalence of CHD in the world. Recessive genotypes may represent a CHD risk factor in Asian populations with a high degree of consanguineous marriages. Genetic analysis of consanguineous families may represent a relatively unexplored source for investigating CHD etiology. To obtain insight into the contribution of recessive genotypes in CHD we analysed a cohort of forty-nine Pakistani CHD probands, originating from consanguineous unions. The majority (82%) of patient's malformations were septal defects. We identified protein altering, rare homozygous variants (RHVs) in the patient's coding genome by whole exome sequencing. The patients had a median of seven damaging RHVs each, and our analysis revealed a total of 758 RHVs in 693 different genes. By prioritizing these genes based on variant severity, loss-of-function intolerance and specific expression in the developing heart, we identified a set of 23 candidate disease genes. These candidate genes were significantly enriched for genes known to cause heart defects in recessive mouse models (P < 2.4e-06). In addition, we found a significant enrichment of cilia genes in both the initial set of 693 genes (P < 5.4e-04) and the 23 candidate disease genes (P < 5.2e-04). Functional investigation of ADCY6 in cell- and zebrafish-models verified its role in heart development. Our results confirm a significant role for cilia genes in recessive forms of CHD and suggest important functions of cilia genes in cardiac septation.

Hesitancy Towards COVID-19 Vaccine Among Students of Medical and Allied Health Sciences in Khyber Pakhtunkhwa.

Objective: To measure COVID-19 vaccine hesitancy and its associated factors among medical and allied health sciences students of Khyber Pakhtunkhwa. Methodology: This cross-sectional survey was conducted online using Google survey platform in March 2021. Study population comprised of medical and allied health sciences students studying in medical/allied health sciences academic institutes in Khyber Pakhtunkhwa. The web-based online link was provided to around 800 students to fill in the questionnaire via email, WhatsApp and/or social media network. Response rate was around 50%. The main outcome variable was vaccine hesitancy. Factors associated with vaccine hesitancy were explored by bivariate and multivariate regression analysis. Results: Out of 398 medical and allied health sciences students, there were 193 (48.5%) males and 205 (51.5%) females with mean age was 22.6± 2.8 years. The vaccine hesitancy rate was found to be 52.8%. A significant relationship between vaccine hesitancy and gender was observed. Other factors including lack of adequate knowledge about vaccines (p < 0.001), Chinese origin of vaccines (p < 0.001), lack of knowledge that vaccination can reduce the chances of acquiring infection (p < 0.001), fear of potential side effects (p < 0.001) and hidden agenda behind free forceful vaccination (p = 0.045), were found to be main barriers or reasons responsible for COVID-19 vaccine hesitancy among medical and allied health sciences students. Conclusion: Important associated barriers with COVID-19 vaccine hesitancy included gender, lack of information, fear of side effects, lack of trust in imported and Chinese vaccines, and perception of hidden agenda behind COVID-19 vaccination.

A histopathological and epidemiological study of urothelial carcinoma at a tertiary care centre in Peshawar, Pakistan.

Bladder cancer is the ninth leading cause of death worldwide and 14th leading cause of death in Pakistan. The objective of this study was to determine the frequency of urothelial carcinoma in various age groups, its gender distribution, and grades. A total of 131 cases of urothelial carcinoma, received at Department of Pathology, Peshawar Medical College, Peshawar, between January 2017 to December 2022, were included in the study; of them 107 (81.6%) were males while 24 (18.3%) were females with a mean age of 62±13 years. The most common histological subtype was papillary urothelial carcinoma in 117(89.3%) cases, followed by Squamous and Glandular in 5(3.8%) cases. Majority of the urothelial carcinoma with high grade showed a statistically significant relation with muscle invasion 38 (50.66%). Males were four times more likely to have urothelial carcinoma while older age groups were more likely to have high grade urothelial carcinoma.

Immunohistochemical Expression of Epidermal Growth Factor Receptor (EGFR) in Oral Squamous Cell Carcinoma and Oral Potentially Malignant Disorders.

BACKGROUND: Increased epidermal growth factor receptor (EGFR) expression has been implicated in several tumors and is associated with increased tumor advancement as well as a potential drug target. The objective of the study was to compare the immunohistochemical expression of EGFR in oral squamous cell carcinoma (OSCC) with oral potentially malignant disorders (OPMDs) and their demographic and pathologic parameters. METHODS: This study was a comparative cross-sectional analytical study. It was conducted at the Department of Pathology, Peshawar Medical College, Riphah International University, Islamabad, Pakistan, from March 2021 to February 2022. The sample size was calculated through G Power. Thirty-eight cases of oral squamous cell carcinoma and 38 cases of oral potentially malignant disorders (OPMDs) were included in the study. Statistical analysis was performed using the Statistical Package for Social Sciences version 20.0. χ 2 tests and Fisher exact tests were applied to compare categorical variables. RESULTS: Mean age of OSCC was 61.6±13.9, with age range from 26 to 90 years. The male-to-female ratio for OSCC was 2.16:1. Buccal mucosa was the most common site involved (34.2%). The most common histologic type was well-differentiated OSCC (71.05%) followed by poorly differentiated (16%) and moderately differentiated (13.15%). The mean age of OPMDs cases was 59.16 ± 10.81 with a male-to-female ratio of 1:1.2. Buccal mucosa was the common site (55.3%), followed by the tongue (18.4%). The OPMDs with dysplasia were 55.2%, and without dysplasia were 44.8%. A total of 55.7% of cases of OSCC showed positive EGFR expression as compared with 36.9% OPMDs cases. A higher number of low-grade OSCC cases showed increased EGFR positivity (59.3%) as compared with high grade (45.45%). EGFR positivity in OPMD cases without dysplasia was 41.2% as compared with cases with dysplasia (33.3%). The EGFR expression in OPMD cases was higher in the ≤50 age group ( P =0.001) and in females ( P =0.032), which was statistically significant. CONCLUSIONS: EGFR expression by Immunohistochemistry may not be a helpful prognostic marker to determine the risk of OPMDs progressing to higher grades of dysplasia or invasive cancer. However, further studies relating this tumor marker to stage, lymph node metastasis, hematogenous metastasis, survival outcomes, and treatment response may give useful information regarding the utility of this marker.

Corrigendum: Additive manufacturing of Al2O3 ceramics with MgO/SiC contents by laser powder bed fusion process.

[This corrects the article DOI: 10.3389/fchem.2023.1034473.].

Correction: Vat photopolymerization-based 3D printing of polymer nanocomposites: current trends and applications.

[This corrects the article DOI: 10.1039/D2RA06522C.].

Anti-nucleocapsid IgG antibodies in SARS-CoV-2 recovered health care workers: One year follow-up study.

Objective: The objective of this study was to evaluate the magnitude and durability of the anti-nucleocapsid-IgG antibody titer in healthcare workers previously infected with SARS-CoV-2 for a period of 12 months.Methods: This study examined blood samples for SARS-CoV-2-specific IgG collected periodically from 120 healthcare workers previously infected with SARS-CoV-2 (confirmed by RT-PCR) and followed longitudinally up to 12 months from their enrolment into the study.Results: The median anti-N-IgG antibody level identified at 3 months was 23.7 CO-index (IQR: 9.13-50.27) and increased to 32.9 CO-index (IQR: 11.8-84.4) at 6 months. At 9 months, the median anti-N-IgG antibody level started to wane in the subsequent time and was dropped to 14 CO-index (IQR: 3.4-37.6) and declined further to 9.8 CO-index at 12 months (IQR: 2.8-9.8). When classified by age groups, the only statistically significant difference in anti-N-IgG between the two age groups (≤30 years and >30 years) was identified at 12 month time point (median difference 8.06, p = 0.035). Spearman correlation coefficient was negatively associated between anti-N-IgG and time interval (r = -0.255, p = 0.000) but was not statistically significant with age of a patient (p > 0.05).Conclusions: In conclusion, SARS-CoV-2 antibody levels started declining after 6 months but remained detectable in the majority of patients up to 12 months.

Comparison of Changes in Speciality Choices and Future Career Plans between Public and Private Medical Students Over Five Years of Medical Studies.

This study aimed to compare medical students' satisfaction with their choice of the medical field in their fifth year to their first year of MBBS and to compare speciality choices and career plans between public and private medical students. It was an online survey conducted from December 2020 to April 2021. Two consecutive classes of final-year medical students from five medical schools (2 public and 3 private) were included. They were asked about their satisfaction with the medical profession, intentions to practice abroad, intended speciality, and career plans in the final year and the first year of medical school via a 24-item semi-structured pre-piloted questionnaire. Of 468 responses (34.41% response rate), 331 (70.7%) were females. There was a significant change (p = 0.002) in the intention of students to practice abroad, however, no significant change (p=0.11) in their satisfaction with the medical profession was observed. Key Words: Career choices, Medical students, Medical schools, Personal satisfaction, Pakistan.

Additive manufacturing of Al2O3 ceramics with MgO/SiC contents by laser powder bed fusion process.

Laser powder bed fusion is a laser-based additive manufacturing technique that uses a high-energy laser beam to interact directly with powder feedstock. LPBF of oxide ceramics is highly desirable for aerospace, biomedical and high-tech industries. However, the LPBF of ceramics remains a challenging area to address. In this work, a new slurry-based approach for LPBF of ceramic was studied, which has some significant advantages compared to indirect selective laser sintering of ceramic powders. LPBF of Al2O3 was fabricated at different MgO loads up to 80 wt%. Several specimens on different laser powers (70 W-120 W) were printed. The addition of magnesia influenced the microstructure of the alumina ceramic significantly. The findings show that when the laser power is high and the magnesia load is low, the surface quality of the printing parts improves. It is feasible to produce slurry ceramic parts without binders through LPBF. Furthermore, the effects of SiC and MgO loads on the microstructure and surface morphology of alumina are compared and analysed.

Vat photopolymerization-based 3D printing of polymer nanocomposites: current trends and applications.

The synthesis and manufacturing of polymer nanocomposites have garnered interest in recent research and development because of their superiority compared to traditionally employed industrial materials. Specifically, polymer nanocomposites offer higher strength, stronger resistance to corrosion or erosion, adaptable production techniques, and lower costs. The vat photopolymerization (VPP) process is a group of additive manufacturing (AM) techniques that provide the benefit of relatively low cost, maximum flexibility, high accuracy, and complexity of the printed parts. In the past few years, there has been a rapid increase in the understanding of VPP-based processes, such as high-resolution AM methods to print intricate polymer parts. The synergistic integration of nanocomposites and VPP-based 3D printing processes has opened a gateway to the future and is soon expected to surpass traditional manufacturing techniques. This review aims to provide a theoretical background and the engineering capabilities of VPP with a focus on the polymerization of nanocomposite polymer resins. Specifically, the configuration, classification, and factors affecting VPP are summarized in detail. Furthermore, different challenges in the preparation of polymer nanocomposites are discussed together with their pre- and post-processing, where several constraints and limitations that hinder their printability and photo curability are critically discussed. The main focus is the applications of printed polymer nanocomposites and the enhancement in their properties such as mechanical, biomedical, thermal, electrical, and magnetic properties. Recent literature, mainly in the past three years, is critically discussed and the main contributing results in terms of applications are summarized in the form of tables. The goal of this work is to provide researchers with a comprehensive and updated understanding of the underlying difficulties and potential benefits of VPP-based 3D printing of polymer nanocomposites. It will also help readers to systematically reveal the research problems, gaps, challenges, and promising future directions related to polymer nanocomposites and VPP processes.

Gene expression and transcriptional regulation driven by transcription factors involved in congenital heart defects.

BACKGROUND: Congenital heart disease (CHD) is one of the most important birth defects caused by more than one mutated gene. Mutations in the genes could cause different types of congenital heart defects including atrial septal defect (ASD), tetralogy of Fallot (TOF), and ventricular septal defect (VSD). OBJECTIVES: Cardiac transcription factors are key players for heart development and are actively involved in controlling stress regulation of the heart. Transcription factors are sequence-specific DNA binding proteins that control the process of transcription and work in a synergistic manner. We aim to characterize core cardiac transcription factors including NKX2-5, TBX, SRF, GATA4, and MEF2, which encode homeobox and MADS domain and play a crucial role in heart development. METHODS: In this study, we have explored the important transcription factors involved in cardiac development and genes controlling the expression and regulation process by using the bioinformatics approach. RESULTS: We have predicted the orthologs and homologs based on their evolutionary history, conserved protein domains, functional sites, and 3D structures for better understanding and presentation of factors responsible for causing CHD. Results showed the importance of these transcription factors for normal heart functioning and development. CONCLUSION: Understanding the molecular pathways and genetic basis of CHD will help to open a new door for the treatment of patients with cardiac defects.

Black soldier fly, Hermetia illucens as a potential innovative and environmentally friendly tool for organic waste management: A mini-review.

The application of black soldier fly (BSF), Hermetia illucens based technology to process organic wastes presents a practical option for organic waste management by producing feed materials (protein, fat), biodiesel, chitin and biofertilizer. Therefore, BSF organic wastes recycling is a sustainable and cost-effective process that promotes resource recovery, and generates valuable products, thereby creating new economic opportunities for the industrial sector and entrepreneurs. Specifically, we discussed the significance of BSF larvae (BSFL) in the recycling of biowaste. Despite the fact that BSFL may consume a variety of wastes materials, whereas, certain lignocellulosic wastes, such as dairy manure, are deficient in nutrients, which might slow BSFL development. The nutritional value of larval feeding substrates may be improved by mixing in nutrient-rich substrates like chicken manure or soybean curd residue, for instance. Similarly, microbial fermentation may be used to digest lignocellulosic waste, releasing nutrients that are needed for the BSFL. In this mini-review, a thorough discussion has been conducted on the various waste biodegraded by the BSFL, their co-digestion and microbial fermentation of BSFL substrate, as well as the prospective applications and safety of the possible by-products that may be generated at the completion of the treatment process. Furthermore, this study examines the present gaps and challenges on the direction to the efficient application of BSF for waste management and the commercialization of its by-products.

Incidence of SARS-CoV-2 re-infection in anti-nucleocapsid IgG-positive healthcare workers: a prospective cohort study.

BACKGROUND : Since the pandemic of SARS-CoV-2 began, our understanding of the pathogenesis and immune responses to this virus has continued to evolve. It has been shown that this infection produces natural detectable immune responses in many cases. However, the duration and durability of immunity and its effect on the severity of the illness are still under investigation. Moreover, the protective effects of antibodies against new SARS-CoV-2 variants still remain unclear. OBJECTIVES: To assess the incidence and associated demographic features of SARS-CoV-2 infection in anti-nucleocapsid IgG-positive and anti-nucleocapsid IgG-negative healthcare workers. MATERIAL AND METHODS: This prospective longitudinal cohort study was conducted in Peshawar Medical College group of hospitals of Prime Foundation. Anti-nucleocapsid IgG sero-positive and anti-nucleocapsid IgG sero-negative healthcare workers were followed for a period of 6 months (from 1 Aug 2020 to 31 Jan 2021), and the incidence of SARS-CoV-2 was confirmed by RT-PCR. RESULTS: A total number of 555 cohorts were followed for a period of 6 months; of them 365 (65.7%) were anti-nucleocapsid-negative (group A) and 190 (34.3%) were anti-nucleocapsid-positive (group B) healthcare workers. The mean age of the study cohort was 33.85 ± 9.80 (anti-N (-), 34.2 ± 10.58; anti-N ( +), 33.5 ± 9.50). The median antibody level in anti-nucleocapsid-positive HCWs was 15.95 (IQR: 5.24-53.4). Male gender was the majority in both groups (group A, 246 (67%), group B, 143 (48%)) with statistically significant difference (P < 0.05). Majority of the HCWs were blood group B in both groups (34% each). None of the 190 anti-nucleocapsid-positive HCWs developed subsequent SARS-CoV-2 re-infection, while 17% (n = 65) HCWs developed infection in anti-nucleocapsid-negative group during the 6-month follow-up period. CONCLUSION: In conclusion, none of the anti-nucleocapsid-positive HCWs developed SARS-CoV-2 re-infection in this study, and the presence of IgG anti-nucleocapsid antibodies substantially reduce the risk of re-infection for a period of 6 months.

Printability for additive manufacturing with machine learning: Hybrid intelligent Gaussian process surrogate-based neural network model for Co-Cr alloy.

AM has revolutionized the manufacturing industry, involving several operating parameters that may affect the properties of the final manufactured part. In AM, LPBF has proved its reliability in producing dense components; however, process development for every material necessitates extensive testing. Even the tiniest change can negate all the data for the same material. It is vital to have a P-P correlation that can train itself following a change in powder or machine to achieve defects-free parts and optimal properties. These goals cannot be met alone by multi-physics. One of the ways to address this issue is to apply ML, but it requires a huge data set for training and testing purposes. A framework has been developed for Co-Cr S-S curves to resolve this issue. Twenty-two experimental S-S curves have been generated to produce YS, TS, and EL data points. In combination with DNN, these data points have been applied to the validated and tested GPS-surrogate model to develop a smart processing window to achieve desired YS, TS, and EL. LP, LSS, HD, and PLT have been selected during the whole framework as inputs, while YS, TS, and EL have been classified as outputs. The output of the smart window was verified experimentally. It is found that the highest YS (1110.91 MPa) is attained using LP = 180 W, LSS = 600 mm/s and HD = 70 µm, while least YS (645.05 MPa) is identified using LP = 160 W, LSS = 900 mm/s and HD = 70 µm. For TS, the maximum (165.91 MPa) and minimum (689.73 MPa) values have been achieved using LP = 180 W, LSS = 900 mm/s and HD = 70 µm, and LP = 180 W, LSS = 1000 mm/s and HD = 70 µm, respectively. In the case of EL, LP = 180 W, LSS = 700 mm/s and HD = 70 µm, and LP = 180 W, LSS = 600 mm/s and HD = 70 µm, resulted 23.04% and 0.789% EL, respectively. Using CC, LP and HD did not significantly affect the TS, YS, and EL, while a negative relationship has been found for LSS with TS, YS, and EL. The smart processing window showed that the YS and TS could be achieved at low-high LP and low LSS at the cost of EL. This study provides a technique for framework development in the case of P-P relation based on the provided inputs and the corresponding outputs, leading toward process smartification.

A systematic analysis of worldwide disasters, epidemics and pandemics associated mortality of 210 countries for 15 years (2001-2015).

In recent years, the unprecedented death tolls resulting from epidemics and natural disasters made everyone interested, from the general public to country heads, to know about the mortality rates. The coronavirus issue is the most recent example all over the media, and everyone is talking about corona-induced mortality. The study aimed to estimate the disaster-induced mortality rates at the global level for two hundred and ten countries for fifteen years (2001-2015). Using a retrospective study design, we extracted datasets from two data sources, EM-DAT and UNFPA, in October 2019. The cut-off time for the data download was midnight Central European Time, October 17, 2019. The most noticeable finding in this study is that, against the common prevailing notion, both developed and developing countries equally carry the brunt of disaster-induced mortality. This study proposes empirical confirmation of the direction and magnitude of any year-over-year correlation of disaster and mortality rates. Furthermore, the analysis of the trend in mortality rate over the past fifteen years concludes it is not linear. However, there are huge variations across the years and the countries. The study is of paramount importance to initiate a debate amongst the concerned policymakers and stakeholders to regularly monitor the disaster-induced mortality rates. So that effective interventions can be devised to decrease the mortality rates.

Identifying higher risk subgroups of health care workers for priority vaccination against COVID-19.

Background: Health care workers (HCWs) are exposed to high risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection due to close contact with infected patients in hospital. The objective of this study was to estimate the seroprevalence and to identify the exposure risk of various subgroups among HCWs to prioritize them for early vaccination. Methods: This was a multicentre cross-sectional study conducted between 15 and 29 June 2020. A total of 987 HCWs were recruited randomly from two major tertiary-care hospitals of Peshawar city, Pakistan. The HCWs included doctors, nurses, paramedics and hospital support staff. The US Food and Drug Administration (FDA)-approved kit was used for the detection of SARS-CoV-2 antibodies. Results: Overall, 310 (31.4%) HCWs were seropositive for SARS-CoV-2 antibodies (95% confidence interval, CI: 28.5-34.4). Seroprevalence was higher in males (33.5%) and in age group 51-60 years (40.9%). Seropositivity increased with increasing age from 8.3% in age group ⩽20 to 40.9% in 51-60 years of age group (p < 0.05). The highest seroprevalence was identified in paramedical staff (42·5%, 95% CI: 36.6-48.6) followed by nursing staff (38·8%, 95% CI: 32.1-45.7). In logistic regression, being a male HCW led to higher risk of seropositivity (odds ratio, OR: 1.50, 95% CI: 1·06-2.13. p < 0.05) compared with female staff members. The odds of seropositivity was higher in nurses (OR: 3·47, 95% CI: 1.99-6.05. p < 0.01), paramedical staff (OR: 3·19, 95% CI: 1.93-5.28. p < 0.01) and hospital support staff (OR: 2·47, 95% CI: 1.29-4.7. p < 0.01) compared with consultants. Conclusion: Overall, our results concluded that nursing and paramedical staff are at higher risk and should be vaccinated on priority.

Advances in Laser Additive Manufacturing of Cobalt-Chromium Alloy Multi-Layer Mesoscopic Analytical Modelling with Experimental Correlations: From Micro-Dendrite Grains to Bulk Objects.

This study presents two analytical models for the laser powder bed fusion (LPBF) process. To begin, the single layer's dimensions were measured using principal operating conditions, including laser power, laser scanning speed, powder layer thickness, and hatch distance. The single-layer printing dimensions were transformed into multi-layer printing using the hatch distance. The thermal history of the printed layers was used as an input to the Johnson-Mehl-Avrami-Kolmogorov model to estimate the average dendrite grain size. LPBF experiments were conducted for a Cobalt-chromium (Co-Cr) alloy to validate the developed model. The average dendrite grain size was estimated using a scanning electron microscope (SEM) combined with "Image J" software. The Vickers hardness test was performed to correlate the average dendrite grain size and operating conditions. A 10-15% mean absolute deviation was presented between experiments and simulation results. In all samples, a Co-based γ-FCC structure was identified. An inverse correlation was established between the laser power and smaller average dendrite grain, while a direct relationship has been determined between laser scanning speed and average dendrite grain size. A similar trend was identified between hatch distance and average dendrite grain size. A direct link has been determined between the average dendrite grain size and hardness value. Furthermore, a direct relationship has connected the laser volume energy density and hardness value. This study will help experimentalists to design operating conditions based on the required grain size and corresponding mechanical characteristics.

Influence of Silicon Carbide on Direct Powder Bed Selective Laser Process (Sintering/Melting) of Alumina.

The powder bed selective laser process (sintering/melting) has revolutionised many industries, including aerospace and biomedicine. However, PBSLP of ceramic remains a formidable challenge. Here, we present a unique slurry-based approach for fabricating high-strength ceramic components instead of traditional PBSLP. A special PBSLP platform capable of 1000 °C pre-heating was designed for this purpose. In this paper, PBSLP of Al2O3 was accomplished at different SiC loads up to 20 wt%. Several specimens on different laser powers (120 W to 225 W) were printed. When the SiC content was 10 wt% or more, the chemical interaction made it difficult to process. Severe melt pool disturbances led to poor sintering and melting. The structural analysis revealed that the micro-structure was significantly affected by the weight fraction of SiC. Interestingly, when the content was less than 2 wt%, it showed significant improvement in the microstructure during PBSLP and no effects of LPS or chemical interaction. Particularly, a crack pinning effect could be clearly seen at 0.5 wt%.

Laser Melting Deposition Additive Manufacturing of Ti6Al4V Biomedical Alloy: Mesoscopic In-Situ Flow Field Mapping via Computational Fluid Dynamics and Analytical Modelling with Empirical Testing.

Laser melting deposition (LMD) has recently gained attention from the industrial sectors due to producing near-net-shape parts and repairing worn-out components. However, LMD remained unexplored concerning the melt pool dynamics and fluid flow analysis. In this study, computational fluid dynamics (CFD) and analytical models have been developed. The concepts of the volume of fluid and discrete element modeling were used for computational fluid dynamics (CFD) simulations. Furthermore, a simplified mathematical model was devised for single-layer deposition with a laser beam attenuation ratio inherent to the LMD process. Both models were validated with the experimental results of Ti6Al4V alloy single track depositions on Ti6Al4V substrate. A close correlation has been found between experiments and modelling with a few deviations. In addition, a mechanism for tracking the melt flow and involved forces was devised. It was simulated that the LMD involves conduction-mode melt flow only due to the coaxial addition of powder particles. In front of the laser beam, the melt pool showed a clockwise vortex, while at the back of the laser spot location, it adopted an anti-clockwise vortex. During printing, a few partially melted particles tried to enter into the molten pool, causing splashing within the melt material. The melting regime, mushy area (solid + liquid mixture) and solidified region were determined after layer deposition. This research gives an in-depth insight into the melt flow dynamics in the context of LMD printing.