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This work is an attempt to evaluate the effect of multi-wall carbon nanotube (MWCNT) reinforcement on the properties of non-crimp fabric (NCF) carbon fiber-reinforced polymer hybrid composite (CFRP). MWCNT NCF-CFRP plates were produced by vacuum infusion. Epoxy-MWCNT mixtures were prepared by adding a surfactant, Triton-X 100, and ethanol and mixing ultrasonically. The plates were subjected to thermal and electrical conductivity, DSC and FT-IR characterizations, and tensile testing. SEM image analyses evaluated tensile fracture surfaces. Results showed that 0.5 wt% MWCNT-reinforced nanocomposite samples exhibited better tensile properties than pure NCF-CFRP composites and other nanocomposite samples. The 1.5% MWCNT reinforced sample was the best conductor at all temperatures. The temperature increases also increase the conductivity. However, the conductivity value of 0.5% MWCNT reinforced material increased significantly at low frequencies such as 100–10,000 Hz. The heat reaction of the 0.5 wt% MWCNT nanocomposite was also a bit higher than that of 1–1.5 % wt MWCNT nanocomposites, indicating a decrease in the cure. [ABSTRACT FROM AUTHOR]

Punching is a widely used and economical manufacturing method. The forces that occurred during punching and the dimensional accuracies of the parts obtained from punching are significant in manufacturing processes. This study aimed to examine the cutting forces that occur in the punching process and the dimensional accuracy of the parts. AA 1050 and AA 1070 sheet materials were used in the experimental studies. Five punches with various cutting-edge geometries were employed in the punching processes. Punching operations were carried out at a constant clearance value and press speed. The geometries of the specimens obtained from the experimental studies were examined using stereo and shuttle-pix microscopes. In addition, the finite element method was used to study punching processes. The consistency of the finite element model was analyzed by comparing experimental and numerical studies. When the flat punch geometry was used, the cutting force was at its greatest. Using the largest angled punch geometry resulted in the lowest cutting force. It has been determined that the dimensional accuracy of the blank and the falling part is better when using the flat punch geometry compared to the other punches used. In addition, it was observed that experimental and theoretical studies are compatible with each other. It is thought that finite element software can provide time and cost savings in determining the cutting force of materials. [ABSTRACT FROM AUTHOR]

In this study, ZK60 alloy, ZK60/15 wt.% TiB2, and ZK60/15 wt.% TiB2 − 0.5 GNPs composites were prepared by hot pressing. The density, microstructure, hardness, and tribological and compression behavior of the samples were investigated. Microstructure investigations showed that TiB2 particles were generally homogeneously dispersed, but GNPs particles were agglomerated. Under 10 and 40 N loads, the best wear performance was obtained with 15 wt.% TiB2 − 0.5 GNPs and ZK60/15 wt.% TiB2 samples, respectively. Abrasion at low and delamination at high loads were observed as the dominant wear mechanism. According to the mechanical test results, the highest hardness (87.1 HV), compressive yield strength (290.1 MPa) and ultimate compressive strength (379.2 MPa) were obtained for the ZK60/15 wt.% TiB2 composite. Fracture surface investigations showed that the mechanism was cleavage fracture and the presence of crack formations on the surface. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the impact of Corona Virus Disease 19 (COVID-19) infection on pregnancy outcomes. STUDY DESIGN: This retrospective study was conducted at a tertiary university hospital between the years of October 2020-October 2021. All the pregnant women with COVID-19 diagnoses were enrolled in the study during this period. Demographic parameters, a history of Favipiravir use, COVID-19 symptoms, treatment approaches, hospitalization, intensive care unit admission, and obstetric and neonatal outcomes were recorded. RESULTS: A total of 92 patients were enrolled in the study. The mean age was 30+5 years. Forty-seven of the patients were asymptomatic (51%). The most common symptoms were respectively; fatigue (37.8%), fever (27.6%), dyspnea (22%), cough (17.8%), headache (11%), anosmia (4.4%), hyperemesis (4.4%), diarrhea (2.2%). There were 20 patients (21.7%) who were hospitalized. Eight of these women (8.6%) required intensive care unit admission due to COVID pneumonia-related acute respiratory distress syndrome. Five of the patients treated in the intensive care unit died due to respiratory failure. Two patients had a miscarriage before the 20th week. There were four stillbirths. The gestational weeks at which fetal death occurred were 24, 26, 28, and 38 weeks of gestation. There were 19 patients with a history of favipiravir use. There was not any other congenital abnormality due to Favipiravir usage. CONCLUSION: Our study showed that COVID-19 disease has similar symptoms in pregnant women to non-pregnant women, according to the literature data. However, COVID-19 infection increases the rates of pregnancy complications and maternal mortality. [ABSTRACT FROM AUTHOR]

Objective: The possibility of pregnancy increases with kidney transplantation in patients with chronic kidney disease. However, graft dysfunction, risk of fetal growth retardation, and fetal anomaly should be monitored closely. In this study, renal and obstetric outcomes were analyzed in pregnant kidney recipients who were followed in our center. Methods: We analyzed 140 reproductive-aged patients who underwent renal transplantation between January 2009 and May 2015, and clinical and laboratory data were evaluated retrospectively. Results: Twenty-four patients became pregnant (17.1%). In pregnant group, median age was significantly lower than nonpregnant group (P = .014). The median age of pregnant group at the time of transplantation was also significantly lower than non-pregnant patients (P < .001). The rate of pregnant patients was 66.7% in 18-25 year age group (P = .008). The rate of urinary tract infection in non-pregnant group was higher than pregnant group (P = .03). Live birth rates were 83.3% and 45.8% of those whose birth weight was higher than 2500 g. The increased level of daily urinary proteinuria and the time from diagnosis of renal failure to transplantation had significant effect on pregnancy (odds ratio = 13.81;95% CI: 2.06-92.45; P = .007 and odds ratio = 3.25;95% CI: 1.11-9.48; P = .031, respectively). Low serum creatinine level had significant protective effect (odds ratio = 0.001; 95% CI: 0-0.30, P = .018). The patients in 18-25 age group were 48.39 times more eligible for pregnancy compared to those in >35 age group (odds ratio = 48.39; 95% CI: 1.26-1860.72; P = .037). Rejection episodes were observed in 1 of pregnant women and 11 of non-pregnant women (P > .05). Conclusion: Pregnancy is possible in kidney transplant recipients of reproductive age. Calcineurin inhibitors and azathioprine seem to be safe. Maternal age, low-serum creatinine, and urinary proteinuria affect pregnancy. The close monitoring of renal function and fetal parameters is very important. [ABSTRACT FROM AUTHOR]

This study focused on optimization of different electrode tip types (Conical round, Flat R3, Flat R6, Flat conical) and welding current parameters to obtain the ideal tensile shear strength of resistance spot welded DP600 steel. Welding processes were carried out at 5 and 7 kA welding currents for each of the 4 different tip types. Experimental results showed that welding current is the most important variable affecting tensile shear strength. As the welding current increased, the tensile shear strength increased. It has been determined that there is a linear relationship between the nugget diameter value and the tensile shear strength. The highest tensile shear strength values were obtained with flat 3 mm radius electrode tips and the lowest with conical round tip electrodes. [ABSTRACT FROM AUTHOR]