Numerical modeling of fluid flow, heat, and mass transfer for similar and dissimilar laser welding of Ti-6Al-4V and Inconel 718

AbstractMost of the researches published on the numerical modeling of laser welding are looking at similar welding, mainly due to the difficulty of simulating the mixing phenomenon that occurs in dissimilar welding. Furthermore, numerical modeling of dissimilar laser welding of titanium and nickel alloys has been rarely reported in the literature. In this study, a 3D finite volume numerical model is proposed to simulate fluid flow, heat, and mass transfer for similar and dissimilar laser welding of Ti-6Al-4V and Inconel 718. The laser source was simulated by volumetric heat distribution, which considers the effects of keyhole and heat transfer on the workpiece. The heat source parameters were calibrated through preliminary experiments, by comparing the simulated and experimental weld pool shapes and dimensions. The model was used to simulate both homogenous and dissimilar laser weldings of Ti-6Al-4V and Inconel 718, and a systematic comparison was carried out through a number of selected experiments. The effects of three distinct levels of laser power (1.25 kW, 1.5 kW, 2.5 kW) on temperature distribution and velocity field in the welds pool were analyzed. Results highlighted the effects of Marangoni forces in the weld pool formation. Furthermore, in order to analyze the mass transfer phenomenon in dissimilar welding, species transfer equations were considered, demonstrating the important role played by the mass mixture in the weld pool formation. Finally, a high level of agreement between simulations and experiments—in terms of weld pool shape and dimensions—was observed in all cases analyzed. This proves the ability of the proposed numerical model to properly simulate both the similar and dissimilar welding of Ti-6Al-4V and Inconel 718 alloys

Success Rate and Complications of Internal Jugular Vein Catheterization With and Without Ultrasonography Guide

Background: Central venous catheterization (CVC) is an important procedure in emergency departments (EDs). Despite existence of ultrasonography (US) devices in every ED, CVC is done using anatomical landmarks in many EDs in Iran. Objectives: This study aimed to compare the traditional landmark method vs. US-guided method of CVC placement in terms of complications and success rate. Patients and Methods: In this randomized controlled trial, patients who were candidate for internal jugular vein catheterization, and referred to Baqiyatallah Hospital ED were randomly allocated into US-guided CVC and anatomical landmarks guided CVC groups. Central vein access time, number of attempts, success rate, and complications in each group were evaluated. Mann-Whitney U, chi-square and Fisher exact tests along with Pearson and Spearman correlation coefficients were used to analyze the data. Results: Out of 100 patients, 56 were male and 44 were female. No significant differences were found between the US-guided and traditional landmark methods of CVC insertion in terms of age, gender, BMI, and site of catheter insertion. The mean access time was significantly lower in the US-guided group (37.12 ± 17.33 s vs. 63.42 ± 35.19 s, P < 0.001). The mean number of attempts was also significantly lower in the US-guided group (1.12 ± 0.3 vs. 1.58 ± 0.64 times, P < 0.001). Eighty-eight percent of patients in the US-guided group were catheterized in the first attempt, while 50% of patients in the traditional landmark group were catheterized in the second or more attempts (P < 0.001). The success rate was 100% in the US-guided group, while it was 88% in the landmark group (P = 0.013). Moreover, the rate of complications was significantly lower in the US-guided group (4% vs. 24%, P = 0.004). Conclusions: The US-guided method for CVC placement was superior to the traditional landmark method in terms of access time, number of attempts, success rate, and fewer complications

Exosomal microRNAs in breast cancer and their potential in diagnosis, prognosis and treatment prediction

The significance of exosomal microRNAs (EmiRs) in breast cancer (BC) diagnosis has been widely addressed over the past decades. However, little information is still available regarding these reliable biomarkers’ impacts on BC early diagnosis, prognosis, and treatment outcome predictions, but their great potential in spotting BC early and their predictive essence in BC prognosis and treatment results are promising against this common cancer. The present review focuses on the most recent findings and advancements of EmiRs applications in BC early diagnosis and treatment prediction and identifies current helpful EmiRs that are widely used in this regard

Experimental data of cathodes manufactured in a convective dryer at the pilot-plant scale, and charge and discharge capacities of half-coin lithium-ion cells.

Megtec Systems pilot-plant scale continuous convective coater. The data was generated as part of an experimental design involving the following coating-drying process variables and ranges: comma bar gap, 80-140 µm; web speed, 0.5-1.5 m/min; coating ratio, 110-150%; drying temperature, 85-110 °C and drying air speed, 5-15 m/s. The manufacturing data include pre-calendered coating thickness, mass loading dry and wet, pre-calendered porosity, spatial autocorrelation and join counting (SAJC) -score for carbon and for fluorine, cell thickness, coating weight and porosity of 15 different electrode coatings and 45 half-coin cells. The electrochemical data was obtained at 25 °C in a Maccor 4000 series battery cycler and consists of charge and discharge capacities at C/20, C/5, C/2, 1C, 2C, 5C and 10C C-rates. Discharge gravimetric and volumetric capacities, rate performance (at 5C:0.2C) and first cycle loss data is also reported. Details of the experimental design and a comprehensive analysis of the data can be found in the co-submitted manuscript (Román-Ramírez et al., 2021). Additional collected data not used in Román-Ramírez et al. (2021) is reported in the present manuscript and include visual observations of coating defects, rheological properties of the electrode slurries (solid content, viscosity, coating shear rate and viscosity at coating shear rate), room temperature and room humidity during the coatings and first cycle loss of the coin cells. Raw and analyzed data is made available. The reported data can be used to extend the analysis reported in Román-Ramírez et al. (2021), and for the comparison of relevant data obtained at different manufacturing scales. [Abstract copyright: © 2021 The Author(s). Published by Elsevier Inc.

Understanding the effect of coating-drying operating variables on electrode physical and electrochemical properties of lithium-ion batteries

The effect of coating and drying process variables (comma bar gap, web speed, coating ratio, drying temperature and drying air speed) on NMC622 cathode physical properties (thickness, mass loading and porosity) and electrochemical properties (gravimetric capacity, volumetric capacity and rate performance) is studied by a design of experiments approach. Electrochemical performance is assessed on half coin cells at C-rates from C/20 up to 10C. The statistical analysis of the data reveals that the cathode physical properties are mainly affected by comma bar gap and coating ratio. The electrochemical properties also show high correlations between comma bar gap and coating ratio for some C-rates. As a second evaluation, the relationship between the cathode half-cell physical characteristics with the electrochemical performance is studied through multiple linear regression analysis. A correlation mainly between coating weight and the electrochemical properties is found. Empirical linear models representing the relationship between the output and input variables are provided, showing correlation coefficients ( ) as high as 0.99

Computerized dietary assessments compare well with interviewer administered diet histories for patients with type 2 diabetes mellitus in the primary healthcare setting

Using a context-based case-control trial, 41 adults with type 2 diabetes mellitus were randomized into four groups to complete dietary assessments (computerized or interviewer administered) at 0, 2 and 8 weeks and food records at 0 and 2 weeks. Repeatability of reported energy, total fat, saturated, polyunsaturated and monounsaturated fatty acids between the computerized and interviewer administered methods were assessed using repeated measures ANOVA. Paired t-tests and Pearson\u27s correlations determined relative validity of the assessments

Hyperspectral imager with folded metasurface optics

Hyperspectral imaging is a key characterization technique used in various areas of science and technology. Almost all implementations of hyperspectral imagers rely on bulky optics including spectral filters and moving or tunable elements. Here, we propose and demonstrate a line-scanning folded metasurface hyperspectral imager (HSI) that is fabricated in a single lithographic step on a 1 mm thick glass substrate. The HSI is composed of four metasurfaces, three reflective and one transmissive, that are designed to collectively disperse and focus light of different wavelengths and incident angles on a focal plane parallel to the glass substrate. With a total volume of 8.5 mm^3, the HSI has spectral and angular resolutions of ∼1.5 nm and 0.075°, over the 750–850 nm and −15° to +15° degree ranges, respectively. Being compact, light weight, and easy to fabricate and integrate with image sensors and electronics, the metasurface HSI opens up new opportunities for utilizing hyperspectral imaging where strict volume and weight constraints exist. In addition, the demonstrated HSI exemplifies the utilization of metasurfaces as high-performance diffractive optical elements for implementation of advanced optical systems

Effect of aquatic therapy on motor skill and executive function in children with Autism Spectrum Disorder

Research has demonstrated the positive effects of different types of physical activity, especially aquatic therapy for children with autism spectrum disorder (ASD). As such, this study aimed to examine the effect of a response-oriented approach using aquatic exercise for children with ASD on motor skills and executive function. In this quasi-experimental design, 40 children aged 7–10 years were randomly assigned to one of two groups: a response-oriented aquatic exercise (ROA) group (n=20) or a control (CON) group (n=20). The Bruininks-Oseretsky Test of Motor Proficiency second edition – Short Form (BOTMP-2) and the Wisconsin Card Sorting Test (WCST) were used to assess motor skill and executive function, respectively. Significant (p≤0.05) differences were found between the ROA and CON groups in receiving (F=38.94, p=0.001) and throwing (F=33.05, p=0.001), static balance (F=44.89, p=0.002), dynamic balance (F=48.51, p=0.010), correct responses (F=3.60, p=0.010), conceptual responses (F=0.34, p=0.010) and perseverative errors (F=1.57, p=0.040). Aquatic exercise was found to be an effective intervention for children with ASD in that it decreases motor deficits and improves executive function. This study provides families, teachers and other specialists with exercise optionality that may be exciting and motivational to children with ASD due to its response-oriented approach