Fatigue assessment of 17-4 PH stainless steel notched specimens made by direct metal laser sintering

Direct metal laser sintering (DMLS) offers economical production of customized components with complex geometries in a shorter design-to-manufacture cycle. Similar to other additive manufacturing (AM) techniques, this method is used for the production of complex geometries that include various kinds of notch geometries. The basic understanding of the fatigue behavior of the notched specimens produced with AM techniques, however, must be substantially improved before the unique features of this rapidly developing technology can be used in critical load bearing applications. The axial and torsional fatigue behavior of severely notched components made of additively manufactured 17-4 PH stainless steel was studied in the present paper. The experimental fatigue tests were performed under axial- and torsional-loading conditions. Cylindrical specimens with notch tip radius of 0.1 mm were employed to evaluate the fatigue behavior of the specimens under different loading conditions

Investigation of Dracocephalum extract based on bulk and nanometer size as green corrosion inhibitor for mild steel in different corrosive media

Abstract In recent years, green corrosion inhibitors derived from natural plant resources have garnered much interest. In the present work, at first, we investigated the corrosion behavior of mild steel (st-37) in the presence, and absence of Dracocephalum extract based on bulk size as a corrosion inhibitor in two widely used acidic environments (0.5 M H2SO4, and 1.0 M HCl), at room temperature. Then, we used Dracocephalum extract based on nanometer size to reduce the optimal concentration of inhibitor, increase the corrosion resistant, and efficiency. Dracocephalum extract does not contain heavy metals or other toxic compounds, and also good characteristics such as low cost, eco-friendly, and widespread availability, make it suitable nature candidate as an environmentally safe green inhibitor. The anticorrosive behavior was assessed using electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP). In all of the studies, the inhibitory efficiency (IE%) increased as the extract dose was increased. But by using nano extract, in addition to maintaining high efficiency, the amount of inhibitor was reduced significantly. The highest IE% is 94% at the best dose of nano extract (75 ppm), but the highest IE% is 89% at the best dose of the bulk extract (200 ppm) in H2SO4 solution. Also, for the HCl solution, the highest IE% is 88% at the best dose of nano extract (100 ppm), but the highest IE% is 90% at the best dose of the bulk extract (400 ppm), by polarization method. The PP results suggest that this compound has an effect on both anodic, and cathodic processes, and that it adsorbs on mild steel surface according to the Langmuir adsorption isotherm. Optical microscopy, scanning electron microscopy (SEM) analysis, and a solid UV–Visible reflection spectrum were used to investigate the alloys' surface morphology

Phylogenetic relationships of Scomberomorus commerson using sequence analysis of the mtDNA D-loop region in the Persian Gulf, Oman Sea and Arabian Sea

Abstract Narrow-barred Spanish mackerel, Scomberomorus commerson, is an epipelagic and migratory species of family Scombridae which have a significant role in terms of ecology and fishery. 100 samples were collected from the Persian Gulf, Oman Sea and Arabian Sea. Part of their dorsal fins was snipped and transferred to micro-tubes containing ethanol; then, DNAs were extracted and HRM-Real Time PCR was performed to designate representative specimens for sequencing. Phylogenetic relationships of S. commerson from Persian Gulf, Oman Sea and Arabian Sea were investigated using sequence data of mitochondrial DNA D-loop region. None clustered Neighbor Joining tree indicated the proximity amid S. commerson in four sites. As numbers demonstrated in sequence analyses of mitochondrial DNA D-Loop region a sublimely high degree of genetic similarity among S. commerson from the Persian Gulf and Oman Sea were perceived, thereafter, having one stock structure of S. commerson in four regions were proved, and this approximation can be merely justified by their migration process along the coasts of Oman Sea and Persian Gulf. Therefore, the assessment of distribution patterns of 20 haplotypes in the constructed phylogenetic tree using mtDNA D-Loop sequences ascertained that no significant clustering according to the sampling sites was concluded

The effect of exercise on concentration of some serum biochemical parameters in Arabian horses

Evaluation of parameters like serum biochemical changes following intense physical activity can provide data which may help in predicting the athletic capacity of horses in racing conditions. In the present study, serum concentration of some biochemical factors was determined before and after intense physical activity in nine, 4-10 years old Arabian horses. The blood samples were collected at 1 h before (T0), just after (T1(, 3 hours (T2) and 24 hours (T3) after running with maximum speed in a 1250-meter course. Measurement of serum values of total protein, albumin, BUN, creatinine and glucose and also serum activity of creatine phosphokinase and lactate dehydrogenase enzymes were done by routine laboratory methods. Data were analyzed statistically with one-way repeated measures ANOVA and Tukey's test. The results showed that all of the measured parameters, except BUN were significantly increased after running. It seems that hemoconcentration caused by severe sweating and stress induced by racing conditions, are the reasons for these changes

Design and evaluation of an educational mobile program for liver transplant patients

Abstract Background Liver transplantation, the last treatment for advanced liver failure, necessitates patient education due to its wide range of complications and subsequent disabilities. The present study was development-applied research and aimed to design a mobile-based educational program to provide liver transplant patients with critical health information. Methods In the first phase of the study, the crucial educational components were collected from the literature and organized in the form of a questionnaire using library studies and available global guidelines. The validity and reliability of this researcher-made questionnaire were confirmed by a panel of experts (n = 15), including gastroenterologists and liver specialists working in the Motahari liver clinic and AbuAli Sina Hospital in Shiraz. The application was designed followed by analyzing the data gathered from the first phase. To evaluate the mobile phone program’s usability, to evaluate the application, 30 liver transplant patients were randomly selected. Results Most educational components covered in the questionnaire were deemed necessary by experts in the first phase. As a result, the educational contents were classified under 10 categories. The application had a good level of usability since the participants’ satisfaction score was 8.1 (out of 9 points). Conclusions Due to the increase in liver transplantation and the use of mobile phones, applications increase the patient’s role in their health, and their awareness. It also leads to a better interaction and follow-up of the patient, the treatment staff of the medical centers

Design and Evaluation of a Mobile Phone-based Recommender System for Patients with Cardiac Arrhythmia

Introduction: Cardiovascular disease is one of the main causes of death worldwide. One of the important factors is readmission due to the lack of training. Considering the widespread use of mobile phones, this study aimed to design a recommender system for patients with cardiac arrhythmia. Method: This is an applied-developmental study that was conducted in a quantitative (descriptive) method and in 2 stages. First, the recommended educational parameters and application requirements of the software were determined based on literature review. Then, the obtained contents were provided to 16 cardiologists working in Shahid Rajaei and Hazrat Rasool Akram Hospitals in Tehran. To evaluate the usability, the application was given to 50 patients with cardiac arrhythmia and was checked with the quiz questionnaire version 5.5. Results: In the recommendations section, experts deemed all items except "Omega-3 consumption" necessary. In the usability evaluation section, the items "Identifying the nearest emergency center, sending the patient’s geographic location to the doctor, finding the nearest medical center, and the possibility of changing color, and calculating BMI" were not confirmed. The usability evaluation of the application with an average score of 7.98±0.62 indicates a good level. Conclusion: The mobile-based recommender application can cause the patients to play a greater role in their treatment and acquire skills in the field of training after hospital discharge and lead to a reduction in re-hospitalization and cost

Vitamin D status as a predictor for liver transplant outcomes

Abstract It is well known that vitamin D plays a pivotal role in immune system modulation; however, its role in liver transplantation (LT) has not yet been well elucidated. This study aimed to assess the association between vitamin D status and LT outcomes. This retrospective cohort study was conducted on 335 registered cirrhotic patients with end-stage liver disease (ESLD) who underwent LT during 2019–2021 and had measurement of serum vitamin D before LT. The association of vitamin D levels before LT with the odds of acute cellular rejection (ACR) and risk mortality was assessed by applying logistic and cox regression, respectively. The mean MELD-Na and serum level of vitamin D were 20.39 ± 9.36 and 21.52 ± 15.28 ng/ml, respectively. In the final adjusted model, there was a significant association between vitamin D deficiency in the pre-transplant period and odds of ACR (odds ratio [OR] 2.69; 95% confidence interval [CI] 1.50–4.68). Although in the crude model, vitamin D deficiency in the pre-transplant period was significantly associated with an increased risk of mortality after two years of follow-up (Hazard ratio (HR) = 2.64, 95% CI 1.42–4.33), after adjustment for potential confounders, the association of vitamin D status and mortality became non-significant (HR = 1.46, 95% CI 0.71–3.00). The present study provides evidence that pre-transplant serum vitamin D levels may be a predictor for ACR in patients with cirrhosis undergoing LT