Background Hypertension is a serious condition that is spread worldwide and may lead to severe complications such as heart attack, stroke, hypertensive retinopathy, and renal failure. Although some genetic and environmental risk factors are known to play a role in the etiology of hypertension, like most of the other multi-factorial diseases, its etiology is yet to be fully elucidated. Our study aimed to investigate the effects of methylenetetrahydrofolate reductase ( MTHFR ) C677T (rs1801133) and A1298C (rs1801131), factor V Leiden ( FVL ) G1691A (rs6025), and prothrombin ( PT ) G20210A (rs1799963) genetic polymorphisms on the development risk of essential hypertension and level of blood pressure in hypertensive patients. Results The frequency of the homozygous polymorphic TT genotype for the MTHFR C677T polymorphism was significantly higher in male hypertensive patients than in the male control group (27% vs 6.3%, p = 0.028). The rate of the variant T allele for the MTHFR C677T polymorphism was also significantly higher in male hypertensive patients compared to male healthy controls (51.4% vs 21.9%, p = 0.0004). There was no difference among hypertensive patients and healthy controls regarding the frequencies of MTHFR A1298C, FVL G1691A and PT G20210A polymorphisms. In addition, we found no difference between genotype groups regarding systolic and diastolic blood pressure levels in hypertensive patients. Conclusions Homozygous polymorphic TT genotype and variant T allele for the MTHFR C677T polymorphism may be considered as a risk factor for the development of essential hypertension in the Turkish male population.
Background Oxidative stress is a contributing factor in the etiopathogenesis of major depressive disorder (MDD). Pediatric studies regarding MDD-oxidative stress relationship are insufficient. In this study, we aimed to compare oxidative stress parameters of pediatric MDD patients with those of the control group and to examine factors affecting these parameters. Results Total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), malondialdehyde (MDA) and superoxide dismutase (SOD) activities of 42 patients with MDD and 38 healthy controls were evaluated. Children depression inventory (CDI) was applied to all participants. In the MDD group, serum levels of TOS, OSI and MDA were higher, while TAS and SOD levels were lower ( p < 0.001). When all participants were examined, oxidative stress increased as the CDI score increased, but in the MDD group, SOD increased as the CDI score increased. Increase in body mass index (BMI) percentile increased the oxidative stress in the MDD group. When factors affecting the presence of MDD were analyzed by binary logistic regression analysis, a one-unit increase in SOD decreased depression by 0.190 times. Conclusions This study showed that oxidative stress increases in children and adolescents with MDD, and the increase in the severity of depression further increases oxidative stress, but when the depression becomes very severe, level of SOD increases compensatorily. It has been observed that high BMI in MDD patients creates an additional burden on oxidative stress. The role of oxidative stress in the etiopathogenesis of MDD in children and adolescents should be evaluated more comprehensively.
This work has been accomplished for synthesizing biodiesel from crude oil extracted from Papaver somniferum L. seeds. The oil content of the seeds was detected to be at 43.51 ± 1.58 % which is higher than most of the feedstock used in biodiesel production. The obtained oil was exposed to the transesterification process under demanded reaction conditions as an L9 (9–runs) orthogonal attempt guessed by the Taguchi method. In conclusion, the highest yield of the produced biodiesel was found at the following optimized reaction conditions: molar ratio for methanol to oil of 9:1, NaOH concentration of 0.75 wt%, reaction temperature of 60 °C, and reaction time of 60 min. The exploration of the prominent reaction factors was acquired thanks to the Taguchi technique and the substantial parameters were found to be as follows: catalyst concentration, molar ratio for methanol to oil, reaction temperature, and reaction time with the contribution factors of 47.18 %, 30.04 %, 16.87 %, and 5.91 %, respectively. The statistical analysis carried out based on the ANOVA demonstrated that the monitored yield (88.97 %) were in good consonance with the estimated yield (89.93 %). In addition, the physicochemical characteristics of produced biodiesel was within the limits given in the global biodiesel standards. It can be concluded that Papaver somniferum L. seed oil can be recommended as a novel and important feedstock for biodiesel production in the close future studies as well as industrial applications when the obstructions will remove for the harvesting of this plant.
This study aimed to develop novel nano fibers loaded with lavender essential oil (LEO) for food packaging via centrifugal spinning technique. LEO was extracted from dried lavender flowers by hydrodistillation. The dominant two of the 16 components of the extract identified by GS-MS were linalool (34.37 %) and linalyl acetate (28.82 %). PVP nanofiber mats loaded with three different concentrations of LEO were fabricated with centrifugal spinning and subsequently crosslinked. Nanofibers were characterized in encapsulation efficiency, morphological, mechanical, chemical, thermal, hydrophobicity and bioactivity aspects. The in-vitro antioxidant effect of nanofiber mats, which increased with the loaded LEO concentration, were determined by DPPH and ABTS methods. This effect was also consistent with the in-situ assessment where nanofibers were applied to minced lamb meat. Moreover, LEO-loaded PVP centrifugal spun positively affected the shelf life by suppressing the growth of aerobic mesophilic bacteria, psychotropic bacteria and, yeast molds that cause spoilage in meat.
In this study, the impacts of ZnCl2 and CdCl2 treatments on the structural and optical properties of ZnS/CdS bilayers and on the parameters of CdTe solar cells with ZnS/CdS junction partners were investigated. CdS and ZnS thin films were grown by chemical bath deposition. In the as deposited ZnS/CdS sample, hexagonal CdS and Zn(S,O) phases were formed. After the application of CdCl2 treatment to the sample, ZnO and CdZnS alloys also appeared. In the ZnCl2 treated bilayer, it was observed that the crystal structure of the CdZnS alloy changed from hexagonal to cubic phase. While similar grain structure was observed in the as deposited and the ZnCl2 treated samples; it was seen that CdCl2 treatment significantly affected the grain form and size. CdCl2 treatment resulted in a large increase of Cd-ratio and a more balanced increase Zn-ratio in ZnCl2 treatment. It was determined that ZnCl2 and CdCl2 treatments caused a decrease in the transmittance of the samples. PL spectroscopy revealed the presence of many structural defects such as interstitial zinc, sulfur vacancies, surface states, cadmium vacancies in all bilayer samples. Solar cells with ZnS/CdS, ZnS/CdS (CdCl2-treated) and ZnS/CdS (ZnCl2-treated) junction partners achieved efficiencies of 4.56%, 5.64% and 5.20%, respectively. Solar cell parameters showed that ZnCl2 treatment increased the FF value, while CdCl2 treatment improved the Voc value. An efficiency of 6.01% was obtained from the ZnS/CdS (CdCl2-treated)/CdTe/CdCl2 cell produced by obtaining the highest efficiency with the ZnS/CdS/CdCl2 junction partner. This cell revealed that applying CdCl2 treatment on CdTe significantly increased Voc and Jsc while deteriorating FF.
Background The effect of posterior tibial slope on the maximum contact pressure and wear volume of polyethylene (PE) insert were not given special attention. The effects of flexion angle, Anterior-Posterior (AP) Translation, and Tibial slope on the max contact pressure and wear of PE insert of TKR were investigated under loadings which were obtained in cadaver experiments by using Archard’s wear law. This study uses not only loads obtained from cadaver experiments but also dynamic flexion starting from 0 to 90 degrees. Method Wear on knee implant PE insert was investigated using a 2.5 size 3 dimensional (3D) cruciate sacrificing total knee replacement model and Finite Element Method (FEM) under loadings and AP Translation data ranging from 0 to 90 flexion angles validated by cadaver experiments. Two types of analyses were done to measure the wear effect on knee implant PE insert. The first set of analyses included the flexion angles dynamically changing with the knee rotating from 0 to 90 angles according to the femur axis and the transient analyses for loadings changing with a certain angle and duration. Results It is seen that the contact pressure on the PE insert decreases as the cycle increases for both Flexion and Flexion+AP Translation. It is clear that as the cycle increases, the wear obtained for both cases increases. The loadings acting on the PE insert cannot create sufficient pressure due to the AP Translation effect at low speeds and have an effect to reduce the wear, while the effect increases with the wear as the cycle increases, and the AP Translation now contributes to the wear at high speeds. It is seen that as the posterior tibial slope angle increases, the maximum contact pressure values slightly decrease for the same cycle. Conclusions This study indicated that AP Translation, which changes direction during flexion, had a significant effect on both contact pressure and wear. Unlike previous similar studies, it was seen that the amount of wear continues to increase as the cycle increases. This situation strengthens the argument that loading and AP Translation values that change with flexion shape the wear effects on PE Insert.
In this paper, in the effective mass approximation, we have investigated the effects of the impurity position, external electric field, and the structure sizes on the linear, third-order nonlinear, and total intersubband optical absorption coefficients and oscillator strength of a spherical multilayer quantum dot. In addition, we have examined the variation of the maximum of the total absorption coefficient and the resonance energy versus the core radius, shell thickness, well width, and the applied electric field. The initial and final states’ wave functions and their associated eigenvalues have been determined by solving the Schrödinger equation of the system using the two-dimensional finite difference method. It is found that the existence of an impurity, as well as its position and the applied electric field has a considerable influence on the optical absorption coefficients and oscillator strength. Furthermore, our results show that the structure sizes (core radius, shell thickness, well width) have a considerable effect on the maximum of the total absorption coefficient and the resonance energy.
Despite being ignored in the modern agricultural approach, wild vegetables have an important use in Turkey and contribute to a balanced diet and food security at the household levels. This study focused on the nutritional content of wild chicory (Cichorium intybus L.) that is widely consumed as a vegetable by people living in rural areas in Turkey. The nutritional value and bioactive compounds and antioxidant contents in twenty-one wild chicory populations from Turkey were investigated by analyzing the leaf. The collected chicory seeds were sown in pots and grown in greenhouse conditions. 40 days after sowing, crude protein, mineral matters (Ca, Mg, P, K, Mn, Cu, Fe, Zn) and antioxidant contents were determined. Significant differences were noted among to chicory populations regarding all the investigated parameters. Crude protein content among the population was between 20.45 and 27.89% and averaged 23.65%. Averaged mineral contents over the populations were ordered as follows: K > Ca > Mg > P > Fe > Mn > Cu. The variation was between 15.3 and 25.8 mgGAE/g extract for total phenolic and between 1.43 and 2.55 µgQE for total flavonoid content. Overall results showed that chicory can contribute to a healthier diet and food security by diversification of food sources. In addition, the geographical origin of the population was important in the traits examined, which can shed light on the selection of genotypes for breeders.
Aim: The aim of this study was to determine the health problems experienced by young adults after the COVID-19 vaccine. Method: This study is a quantitative and descriptive study and was completed with 590 undergraduate students studying at a state university in Central Anatolia in the spring semester of the 2021-2022 academic year. The data were collected by the researcher through a one-to-one interview with the students and a questionnaire prepared in line with the literature. Number, percentage and chi-square tests were used in the analysis of the data. Results: A total of 81.4% of the students participating in the study had the BioNTech-Pfizer vaccine. A total of 67.3% of them had two doses of COVID-19 vaccine, 35.9% of the vaccinated students experienced some health problems in the days following the vaccination, and the most common health problems were fatigue, a cough, sleep disturbance, psychological discomfort, a heart ache feeling and sweating. Most of the post-vaccine health problems lasted for 2 days, 3.7% of the participants were diagnosed with hypertension, 2.7% were diagnosed with diabetes mellitus and 10.52% of the female participants went to the doctor due to menstrual irregularity and received treatment. It was determined that 12.2% of the vaccinated students gained weight after vaccination and 63.89% of those who gained weight attributed this to increased appetite, 9.2% continued to have a cough and 9.2% used herbal products. Conclusion: It was determined that one out of every three young adults experienced a health problem after the COVID-19 vaccine. It is recommended that studies be conducted in different sample groups.
It has become increasingly popular in recent years to create improved functionalized nanomaterials in an effort to enhance their physicochemical, catalytic, and biological capabilities. In this study, eco-friendly, especially water dispersible bio-nanocomposites containing metal ferrite, MFe 2 O 4 (M: Cu, Ni, Cd, Mn and Co) nanoparticle were synthesized low-cost method from hemp biomass and characterized by ATR-FTIR, XRD, SEM, TEM (STEM), EDX, VSM, Uv-Vis and TG/DTG analyses. The variation of their ionic conductivity with temperature and concentration and also their catalytic effects against cationic dyes such as methylene blue (MB), crystal violet (CrV) and malachite green oxalate (MGO) were investigated. XRD patterns and FTIR spectra of the AHB-MFe 2 O 4 , especially the stretching of Fe-O and M-O, showed the formation of metal ferrite bio-nanocomposites. Also, interaction between the biomass and metal ferrite nanoparticles was obviously seen from XRD patterns and FTIR spectra of the AHB-MFe 2 O 4 . It was determined that AHB-MFe 2 O 4 bio-nanocomposites have high thermal stability, high ionic conductivity and negative surface charge. Moreover, they exhibited high catalytic performance against cationic dyes such as MB, CrV and MGO.
A new design of a triple band perfect metamaterial absorber based on Pythagorean fractal geometry is proposed and analyzed for terahertz sensing applications. The proposed design showed an enhanced sensing performance and achieved three intensive peaks at 33.93, 36.27, and 38.39 THz, corresponding to the absorptivity of 98.5%, 99.3%, and 99.6%, respectively. Due to the symmetrical nature of the recommended design, the structure exhibited the characteristics of inde-pendency on the incident wave angles. Furthermore, a parametric study was performed to show the effects of the change in substrate type, resonator material, and substrate thickness on the absorption spectrum. At a fixed analyte thickness (0.5 μm), the resonance frequency of the design was found to be sensitive to the refractive index of the surrounding medium. The proposed design presented three ultra-sensitive responses of 1730, 1590, and 2050 GHz/RIU with the figure of merit (FoM) of 3.20, 1.54, and 4.28, respectively, when the refractive index was changed from 1.0 to 1.4. Additionally, the metamaterial sensor showed a sensitivity of 1230, 2270, and 1580 GHz/μm at the three resonance frequencies, respectively, when it was utilized for the detection of thickness variation at a fixed analyte refractive index (RI) of 1.4. As long as the RI of the biomedical samples is between 1.3 and 1.4, the proposed sensor can be used for biomedical applications.
This study investigated the effect of melatonin (MEL) application on pepper plants grown in calcareous environments at different growth stages. High pH negatively affects mineral nutrient uptake. The possible effects of exogenous MEL application on mineral nutrient uptake were investigated in pepper plants exposed to pH stress. In the experiment, the Miray pepper cultivar seedlings were used, and 0 and 5 μM MEL were applied to the seedlings at the stage of 4 full leaves. Two days after application, seedlings were planted in 5‑liter pots to which 0, 1, and 4% agricultural lime (CaCO3) were added to the 1:1 (w:w) peat: perlite mixture. Leaf and root samples were taken twice, 30 days (flowering stage) and 90 days (fruiting stage) after transplanting the seedlings from plants planted in MEL treated and added lime medium. In these samples, there are vegetative growth criteria (plant height, leaf area, fresh and dry weight), some biochemical properties (total phenolic, proline, malondialdehyde, chlorophyll, and anthocyanin), and some biochemical properties (total phenolic, some mineral matter contents) were studied. In general, the negative effects of lime application on vegetative growth were mitigated by applying MEL. It was determined that plant height increased with MEL application and ranged from 42.89 cm (1 Ca‑5 MEL) to 25.11 cm (4 Ca‑0 MEL) at the flowering stage. The leaf area increased from 467.60 cm2/plant (4 Ca‑0 MEL) to 1098.23 cm2/plant (1Ca‑5 MEL). The application of MEL decreased the proline and malondialdehyde (MDA) contents, while the chlorophyll and anthocyanin contents increased. Examining the applications in terms of mineral matter uptake in general, the P, K, Ca, Mg, Cu, and Mn contents in leaves increased during flowering. The P, K, Mg, Cu, and Fe contents in roots increased with the 1% Ca and MEL applications. According to the test results, applying MEL in calcareous environments positively affects plant growth by regulating plant growth, improving biochemical properties, and regulating the uptake of mineral nutrients.
Forest fires are highly destructive phenomena in both ecological and economic terms. Therefore, it is significant to develop measures to detect and mitigate them. In this study, the forest fire risk map of the Milas district of Turkey was studied using geographical information systems and remote sensing methods. In the first part of the study, the forest fire risk map of the area was developed via a weighted overlay technique with analysis of stand characteristics, topographic features, distance from intermittent streams and built-up environment. According to the resulting forest fire risk map, extremely low-, low-, medium-, high- and extremely high-risk classes covered 0%, 0.5%, 65%, 30% and 0.5% of the forested areas in Milas district of Turkey, respectively. In the second part, the location of a major forest fire, which took place in 2007 in the study area, was determined using the normalized difference vegetation index, the normalized burn ratio, and the burn area index. When compared with the forest fire risk map, it was revealed that 45% of the burned areas in 2007 fell into the high-risk class, while 51% of it was from the extremely high-risk zones. Moreover, the forest risk map was compared with eleven forest fire cases between 2013 and 2019. The results show that eight of these fires took place in high-risk territories. According to these results, it was concluded that the created risk map coincides with the fire incidents.
Background: During the coronavirus disease (COVID-19) pandemic, if it is considered that educated manpower is the most valuable resource of countries, it can be thought that various policies should be developed both at the macro- and micro-levels to minimize the loss of healthcare employees. Objective: This study aims to determine the effects of the corporate policies for COVID-19 on the work stress and anxiety of healthcare employees. Method: The sample of the study consists of 136 of 265 healthcare employees in Sakarya Provincial Health Directorate Emergency Health Services in Turkey. The average age of the participants was 34.43 years old; the average duration of professional experience was 12.12 years. Approximately 61% of the participants are male and 51% have a bachelor's degree or higher level. A questionnaire form was used in the study as the data collection tool consisting of socio-demographic characteristics, institutional policies on COVID-19, work stress, and the Status Anxiety Scale. Process Macro Model 4, descriptive statistics and correlation analysis were used for the data analysis. Results: According to the results of the study, the corporate policies for COVID-19 perception of participants was above average (3.30±0.82) while work stress (2.99±0.88) and anxiety (2.65±0.56) were below average. The corporate policies for COVID-19 perception of participants reduced their work stress (β= - 0.430) and anxiety (β= - 0.361). Additionally, anxiety played a mediating role in the effect of the corporate policies for COVID-19 perception on work stress, and it further raised the impact of corporate policies for COVID-19 perception on the work stress reduction (β= - 0.169). Conclusions: During the COVID-19 pandemic, health managers should determine and control the anxiety and stress levels of the health employees on their staff and take a number of steps to reduce their anxiety and stress.
The greatest weakness of concrete as a construction material is its brittleness and low fracture energy absorption capacity until failure occurs. In order to improve concrete strength and durability, silica fume SF is introduced into the mixture, which at the same time leads to an increase in the brittleness of concrete. To improve the ductility and toughness of concrete, short steel fibers have been incorporated into concrete. Steel fibers and silica fume are jointly preferred for concrete design in order to obtain concrete with high strength and ductility. It is well-known that silica fume content and fiber properties, such as aspect ratio and volume ratio, directly affect the properties of SFRCs. The mixture design of steel-fiber-reinforced concrete (SFRC) with SF addition is a very important issue in terms of economy and performance. In this study, an experimental design was used to study the toughness and splitting tensile strength of SFRC with the response surface method (RSM). The models established by the RSM were used to optimize the design of SFRC in terms of the usage of optimal silica fume content, and optimal steel fiber volume and aspect ratio. Optimum silica fume content and fiber volume ratio values were determined using the D-optimal design method so that the steel fiber volume ratio was at the minimum and the bending toughness and splitting tensile strength were at the maximum. The amount of silica fume used as a cement replacement, aspect ratio, and volume fraction of steel fiber were chosen as independent variables in the experiment. Experimentally obtained mechanical properties of SFRC such as compression, bending, splitting, modulus of elasticity, toughness, and the toughness index were the dependent variables. A good correlation was observed between the dependent and independent variables included in the model. As a result of the optimization, optimum steel fiber volume was determined as 0.70% and silica fume content was determined as 15% for both aspect ratios.
This study aims to determine whether exposure to non-ionizing radiofrequency fields could induce an adaptive response (AR) in adult mice and to reveal potential molecular mechanisms triggered by RF-induced AR. The study was performed on 24 adult male Swiss-Albino mice. The average mass of the mice was 37 g. Four groups of adult mice, each consisting of 6, were formed. The radiofrequency group (R) and the adaptive response group (RB) were exposed to 900 MHz of global system for mobile communications (GSM) signal at 0.339 W/kg (1 g average specific absorption rate) 4 h/day for 7 days, while the control group (C) and the bleomycin group (B) were not exposed. 20 minutes after the last radiofrequency field (RF) exposure, the mice in the B and RB groups were injected intraperitoneal (ip) bleomycin (BLM), 37.5 mg/kg. All the animals were sacrificed 30 minutes after the BLM injection. Oxidative damage and antioxidant mechanism were subsequently investigated in the blood samples. Changes in the expression of the genes involved in DNA repair were detected in the liver tissue. TUNEL method was used to determine the apoptosis developed by DNA fragmentation in the liver tissue. The RB group, which produced an adaptive response, was compared with the control group. According to the results, the increase of reactive oxygen species (ROS) in the RB group may have played an important role in triggering the adaptive response and producing the required minimum stress level. Furthermore, tumor suppressor 53(p53), oxo guanine DNA glycosylase (OGG-1) levels responsible for DNA repair mechanism genes expression were increased in conjunction with the increase in ROS. The change in the poly (ADP-ribose) polymerase 1 (PARP-1) and glutathione peroxidase 1 (GPx-1) gene expression were not statistically significant. The antioxidant enzyme levels of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (TAC) were decreased in the group with adaptive response. According to the data obtained from terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis, apoptosis was decreased in the RB group due to the decrease in cell death, which might have resulted from an increase in gene expression responsible for DNA repair mechanisms. The results of our study show that exposure to RF radiation may create a protective reaction against the bleomycin. The minimal oxidative stress due to the RF exposure leads to an adaptive response in the genes that play a role in the DNA repair mechanism and enzymes, enabling the survival of the cell.
The first purpose of this systematic review is to describe how empirical studies on the applications of the 5E instructional model are distributed according to certain variables. The second purpose is to determine how the 5E model has shown a trend in empirical studies in the transition from inquiry-based teaching to STEM education over the years within the scope of learning outcomes of the 5E model. A total of 74 empirical articles out of the 201 obtained from the initial search with the keyword ‘5E model’ in the Web of Science (WoS) and Education Resources Information Center (ERIC) databases were subjected to descriptive and content analysis. The outstanding conclusion from the synthesis of these empirical studies in which the 5E model was implemented is that the 5E model, which has had a broad impact for a long time, focused on its effects on sublevel thinking levels of Bloom's taxonomy (knowledge, understand), and its effects on higher-order thinking levels, which have a crucial place in science education, are overshadowed. Based on these results, a ‘skill-based STEM instructional model’ with an activity set prepared by the model has been proposed in this study concerning 21-st century skills based on the 5E model.
Testing, one of the methods to combat the COVID-19 outbreak, is highly recommended in all countries. Empirical studies on how testing relates to the control of new cases will help highlight the importance of testing in efforts to combat the epidemic. Therefore, this study aims to investigate the relationship between COVID-19 testing and COVID-19 cases. We use panel autoregressive distributed lag analysis to test the effect of COVID-19 test number on the COVID-19 new cases. The data of the study cover the period from March 19, 2020, to May 01, 2020, for 14 OECD countries. Data were obtained from the https://ourworldindata.org/coronavirus website. According to the results, this study shows that increasing the COVID-19 test number will help to reduce new COVID-19 cases. On the other hand, increase in the test number per thousand will probably not contribute to reducing new COVID-19 cases, because countries do not already test by random selection, and even if they do, it will not contribute to detection and isolating of the new cases without identifying risky groups.
Ethical violations can cause wasteful use of resources, unfair advantage for some scientists over others, and setting a bad example to the scientific community and young scientists. Awareness of these violations helps to prevent moral contamination of the academic community. A web-based survey with 30 items was sent to all residents and academic staff worked at different faculties in our university to evaluate the participants' thoughts and knowledge about academic publication ethics. There were 48 female and 53 male respondents. 44.6% of the participants had never taken ethics courses. 57.4% of the participants think that the ethics course should be given throughout life. The responses to “when ethical course should be given?” was significantly different between males and females, but not according to academic titles and age ranges. Except residents, all participants had complete information about the predatory journals, books and congresses. 29% of the participants were not aware of ghost authorship and 20% were misinformed. The participants did not have sufficient knowledge and awareness about plagiarism, except for some sub-titles. Although lack of awareness is mostly evident among non-academicians, both academicians and non-academicians need to be educated and trained about plagiarism.
The effect of tool rotation speed and welding speed on the microstructural and mechanical properties of AA 7075‐T651 welded plates produced using friction stir welding is the research subject of this study. A basin‐shaped stir zone characterized all friction stir welded joints’ microstructures. The fracture location following the tensile test was found to be outside the stir zone for each welded joint. All welded joints were subjected to a 90° root bending test. The tests were terminated before each welded joint could reach the 90° bend angle in the stir zone. The stir zone of each welded joint was characterized by the fine and equiaxed grains with the effect of dynamic recrystallization. In addition, intermetallic particles were also detected to occur in the weld joint. Among the nine welded joints, the welded joint with the highest ultimate tensile strength of 382 MPa was produced with a tool rotation speed of 400 min−1 and a welding speed of 80 mm min−1. The highest welding efficiency of 71 % was obtained with the welding process parameters of 400 min−1 tool rotational speed and 80 mm min−1 welding speed. Increasing tool rotation speed caused the grain size to be coarser. In this study, AA 7075 aluminum alloy plates were joined using friction stir welding with pentagonal profiled pin. Tool rotation and welding speeds were evaluated to be effective on the microstructural and mechanical properties of AA 7075 friction stir welded plates. A coarser grain size in stir zone led to a lower ultimate tensile strength.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.