Thermomechanical Modeling of Material Flow and Weld Quality in the Friction Stir Welding of High-Density Polyethylene.

A thermomechanical model of the friction stir welding (FSW) of high-density polyethylene (HDPE) was developed by incorporating a Coupled Eulerian-Lagrangian (CEL) approach. A Johnson Cook (JC) material model of HDPE was developed through experimentally generated strain-rate- and temperature-dependent stress strain data. Two sets of FSW process parameters with minimum and maximum weld defects were numerically modeled. The numerically calculated temperature distribution, material flow and flash and potential defects were validated and discussed with the experimental results. Tracer particles allowed to visualize the material movement during and after the tool had traversed from the specified region of the workpiece. Both numerical models presented similar maximum temperatures on the upper surface of the workpiece, while the model with high traverse speed and slow rotational speed had narrower shoulder- and heat-affected zones than the slow traverse, high rotational speed model. This contributed to the lack of material flow, hence the development of voids and worm holes in the high traverse speed model. Flash and weld defects were observed in models for both sets of process parameters. However, slow traverse, high rotational speeds exhibited smaller and lesser weld defects than high traverse, slow rotational speeds. The numerical results based on the CEL approach and JC material model were found to be in good agreement with the experimental results.

A Study of the Friction Stir Lap Welding of AA5052 and Polypropylene.

Friction stir lap welding (FSLW) remains a pioneering technique for creating hybrid joints between AA5052 aluminium alloy and polypropylene (PP), particularly with the metal-on-top configuration. Building upon previous research, this study introduces a tapered fluted pin tool design and investigates its effectiveness in the welding process. Our results, supported by ANOVA, chemical, and microstructural analyses, reiterate that the optimal welding parameters stand at a rotational speed of 1400 RPM and a traverse speed of 20 mm/min. This combination produces a joint tensile strength of 3.8 MPa, signifying 16.54% of the weaker material's inherent strength. Microstructural evaluations revealed a unique composite of aluminium chips intermeshed with PP, strengthened further by aluminium hooks. Crucially, mechanical interlocking plays a predominant role over chemical bonding in achieving this joint strength. The study underscores the absence of significant C-O-Al bonds, hinting at the PP degradation without the thermo-oxidation process. Additionally, joint strength was found to inversely correlate with the interaction layer's thickness. The findings fortify the promise of FSLW with the novel fluted pin design for enhancing joints between AA5052 and PP, emphasising the potential of mechanical interlocking as a principal factor in achieving high-quality welds.

Visual, Non-Destructive, and Destructive Investigations of Polyethylene Pipes with Inhomogeneous Carbon Black Distribution for Assessing Degradation of Structural Integrity.

Carbon black (CB) is used in polyethylene (PE) pipes to protect against thermal and photooxidation. However, when CB is not properly dispersed in the PE matrix during processing, white regions having little or no CB concentration, known as "windows," appear within the CB/PE mixed black compound. In some cases, windows can drastically affect the structural integrity of both the pipe and butt fusion joint. In this work, PE pipes with varying amounts of windows were investigated for their characteristic window patterns, as well as quantifying the area fraction of windows (% windows). Tensile test on specimens with known % windows determined a critical limit above which the fracture strain rapidly degrades. Micro-tensile and micro-indentation results showed tear initiation at the window-black PE matrix boundary; however, they did not confirm the mechanism of tear initiation. In support of this work, a method of making thin shavings of a whole pipe cross section was developed, and the best viewing windows under cross-polarized monochromatic light were identified. In addition, a phased array ultrasonic test (PAUT) and microwave imaging (MWI) were directly applied to the pipe and confirmed the presence and patterns of the windows.

The relationship between carpal tunnel syndrome, smartphone use, and addiction: A cross-sectional study.

Objectives: This study aims to investigate the use of and addiction to smartphones in individuals with and without carpal tunnel syndrome (CTS). Patients and methods: The cross-sectional study included a total of 404 participants (286 females, 118 males; mean age: 39.7±11.6 years; range, 16 to 75 years) who applied to the Neurology Department of the Firat University Faculty of Medicine, between April 2019 and October 2019. The participants were divided into two groups: 202 patients diagnosed with CTS were included in the case group, and 202 patients and their relatives who did not have hand and wrist complaints were included in the control group. The diagnosis of CTS was made by evaluating the history, physical examination, and electromyography findings. Data were collected with participant information forms and the Smartphone Addiction Scale. Results: It was found that the risk of CTS increased 1.022 times with a one-unit increase in the SAS score and 1.292 times with a 1-h increase in daily smartphone use. Conclusion: Smartphone addiction can be considered as a potential risk factor for CTS; however, the effect of smartphone addiction on CTS severity was not examined in this study. The relationship between disease severity, smartphone use, and smartphone addiction in CTS patients requires further investigation to provide clarification on this issue.

COVID-19 anxiety and hygiene status in vocational schools of health services students in Turkey: A multicenter study.

BACKGROUND: While the coronavirus (COVID-19) pandemic creates fear and anxiety on the students' academic achievement, the risk of an infectious disease may negatively affect education by reducing the concentration ability of students. Thus, it is essential to evaluate the knowledge, behaviors, anxiety levels, and hygiene status of students. OBJECTIVE: This study aimed to investigate the knowledge, behavior change, anxiety, and hygiene status of university students about COVID-19. METHODS: The investigation was conducted with students of three vocational schools of health services located in different provinces of Turkey (n = 1055). Data collected by an online survey consisted of knowledge questions about COVID-19, items about behavior change, the hygiene behavior scale (HBS), and the Generalized Anxiety Disorder 7 (GAD-7) scale. RESULTS: The knowledge scores of women were significantly higher than the scores of men. Of the students, 59.6%showed positive hygiene behaviors, and 31.5%had anxiety. Female students' total HDC scale score was significantly lower than that of men, and the total HDC scale score of those who received hand hygiene education was significantly lower than that of participants who did not receive training, which shows a positive hygiene behavior. The total GAD-7 scale score of women was significantly higher than that of men. More than half of the students showed positive hygiene behaviors, and about a third had anxiety. CONCLUSIONS: Based on the study's results, psychological support and training should be provided to students.

Correction: Ahmad, I.A., et al. Non-Isothermal Crystallisation Kinetics of Carbon Black-Graphene-Based Multimodal-Polyethylene Nanocomposites. Nanomaterials, 2019, 9, 100.

In the published paper [¹], there was a typo error mistake in Equation (5), which was supposed to be expressed as " log Z t + n log t = log K T - m log Φ " instead of "log Zt + n log t = log KT - ml" [...].

Non-Isothermal Crystallisation Kinetics of Carbon Black- Graphene-Based Multimodal-Polyethylene Nanocomposites.

The effect of carbon black (CB) and microwave-induced plasma graphene (g) on the crystallisation kinetics of the multimodal high-density polyethylene was studied under non-isothermal conditions. The non-isothermal crystallisation behaviour of the multimodal-high-density polyethylene (HDPE), containing up to 5 wt.% graphene, was compared with that of neat multimodal-HDPE and its carbon black based nanocomposites. The results suggested that the non-isothermal crystallisation behaviour of polyethylene (PE)-g nanocomposites relied significantly on both the graphene content and the cooling rate. The addition of graphene caused a change in the mechanism of the nucleation and the crystal growth of the multimodal-HDPE, while carbon black was shown to have little effect. Combined Avrami and Ozawa equations were shown to be effective in describing the non-isothermal crystallisation behaviour of the neat multimodal-HDPE and its nanocomposites. The mean activation energy barrier (ΔE), required for the transportation of the molecular chains from the melt state to the growing crystal surface, gradually diminished as the graphene content increased, which is attributable to the nucleating agent effect of graphene platelets. On the contrary, the synergistic effect resulting from the PE-CB nanocomposite decreased the ΔE of the neat multimodal-HDPE significantly at the lowest carbon black content.

Advancing the Use of High-Performance Graphene-Based Multimodal Polymer Nanocomposite at Scale.

The production of an innovative, high-performance graphene-based polymer nanocomposite using cost-effective techniques was pursued in this study. Well-dispersed and uniformly distributed graphene platelets within a polymer matrix, with strong interfacial bonding between the platelets and the matrix, provided an optimal nanocomposite system for industrial interest. This study reports on the reinforcement of high molecular weight multimodal-high-density polyethylene reinforced by a microwave-induced plasma graphene, using melt intercalation. The tailored process included designing a suitable screw configuration, paired with coordinating extruder conditions and blending techniques. This enabled the polymer to sufficiently degrade, predominantly through thermomechanical-degradation, as well as thermo-oxidative degradation, which subsequently created a suitable medium for the graphene sheets to disperse readily and distribute evenly within the polymer matrix. Different microscopy techniques were employed to prove the effectiveness. This was then qualitatively assessed by Raman spectroscopy, X-ray diffraction, rheology, mechanical testing, density measurements, thermal expansion, and thermogravimetric analysis, confirming both the originality as well as the effectiveness of the process.

Effect of urinary incontinence and its subtypes on quality of life of women in eastern Turkey.

OBJECTIVE: To determine the bothersomeness and effect on quality of life (QOL) of different types of urinary incontinence (UI) in married women living in eastern Turkey. MATERIALS AND METHODS: A total of 1049 married women was evaluated in the present population-based, cross-sectional study. QOL was assessed using a validated form of the Turkish version of the Incontinence Impact Questionnaire Short Form. The effects of UI subtype on the overall QOL score and on the individual domain scores were determined. The relationship between several demographic characteristics such as age, weight, education level, number of pregnancies, number of live deliveries, and presence of pelvic organ prolapse and the QOL changes was examined. RESULTS: The mean age of the women was 44.62 ± 11.01 years (range 17-80). Of the women with UI, 76.2% stated that the UI had a negative effect on their QOL. Women with mixed UI and severe UI had the worst QOL scores. The QOL changes for the different domains revealed that entertainment activities were affected least, and emotional health and feelings of frustration were the 2 domains that showed the most significant deterioration. Furthermore, older and unemployed women, housewives, women living in urban areas, and women with multiple births, difficult labor, and increased weight experienced significant negative effects on their QOL. CONCLUSION: Our results have shown that, regardless of different factors, UI has significant negative effects on QOL. The presented data emphasize the importance of the high prevalence of UI in our region and its negative effects on QOL. Thus, additional policies are needed for the prevention of the negative effects of UI.

The frequency of depression and menopause-related symptoms in postmenopausal women living in a province in Eastern Turkey, and the factors that affect depressive status.

BACKGROUND: This study was designed to determine depression in women in the postmenopausal stage in Elazig city, located in Eastern Turkey, and determine the factors affecting depressive status. MATERIAL/METHODS: The sample included 546 women and of these, 519 could be contacted. A questionnaire was conducted with the women who were included in the study. This included demographic properties, which are thought to affect depression. Subjects were given the Beck Depression Inventory (BDI). RESULTS: In total, 97.7% of women reported that they experienced a problem or had complaints during menopause, while 54.9% reported that they experienced problems in their sexual lives. The mean BDI score of women was 17.01+/-8.75. The ratio of women whose total scores were higher than the breakpoint of 17 was 42.2%. Single, widowed, and divorced women had higher ratios than married women; primary school or lower education women had higher ratios than high school or lower education graduate women; the women who reported that they had problems in their sexual lives had higher ratios than the other women within the survey; the women who were subject to violence at any time during their lives had higher ratios than the women who had not experienced violence (P<.05). CONCLUSIONS: The frequency of depression symptoms in women living in Elazig is high. The information and services that the local women receive about menopause are inadequate.

Prevalence and risk factors of female urinary incontinence in eastern Turkey.

OBJECTIVES: To evaluate the prevalence of urinary incontinence (UI) and determine risk factors for its development in women living in eastern Turkey. METHODS: A cross-sectional study was conducted on 2275 women aged between 17 and 80 years. A questionnaire examining demographic characteristics, parity and pelvic organ prolapse was given. Presence and types of incontinence were examined using a validated form of the Turkish version of the urogenital distress inventory questionnaire-short form (UDI-6). RESULTS: A total of 1054 (46.3%) women reported involuntary loss of urine. Stress UI was present in 46% of women, whereas urge UI was detected in 43% of them. Mean age of patients with and without UI were 44.57 + 11.04 and 35.04 + 9.51, respectively. Age, total number of pregnancies and number of deliveries were shown to be significantly different in patients with and without any type of UI. Multiple logistic regression analysis of the factors revealed that age, total delivery number, pelvic organ prolapse and difficult labor were significantly associated with the presence of UI. CONCLUSIONS: This is the first study examining the prevalence of UI in women living in eastern Turkey. By using a validated questionnaire, several risk factors for the development of UI were determined. Pelvic organ prolapse and increased number of births were found to be two most significant ones.