Shear Induced Fiber Alignment and Acoustic Nanoparticle Micropatterning during Stereolithography

The stereolithograpy method, which consists of a light source to polymerize the liquid photocurable resin, can produce structures with complex shapes. Most of the produced structures are unreinforced neat pieces. The addition of reinforcement, such as fibers and particles are regularly utilized to improve mechanical properties and electrical conductivity of the printed parts. Added fibers might be chosen as short or continuous fibers and the properties of the reinforced composite materials can be significantly improved by aligning the fibers in preferred directions. The first aim of this dissertation is to enhance the tensile and flexural strengths of the 3d printed composites by using shear induced alignment of short fibers. The second aim is to print parts with conductive embedded microstructures by utilizing acoustic patterning of conductive particles. Both aims are utilized during the stereolithography process.A lateral oscillation mechanism, which is inspired by large amplitude oscillatory shear test, was designed to generate shear flow. The alignment method, which combines the lateral oscillation mechanism with 3d printed wall patterns, is developed to utilized shear flow to align the fibers in the patterned wall direction. Shear rate amplitude, fiber concentration, and patterned wall angle were considered as parameters during this study.The stereolithography device incorporated with oscillation mechanism was utilized to produce short fiber reinforced ceramic composites and short nanofiber reinforced polymer composites. Nickel coated short carbon fibers, alumina and silica short fibers were used to reinforce the ceramic matrix with different fiber contents. The printed walls were demonstrated to align the short fibers parallel to the wall which was different from the oscillation direction up to 45°. The flexural strength of the ceramic matrix was improved with the addition and alignment of the short fibers. The alumina nanofibers were used as reinforcement in the photocurable polymer resin. The alumina nanofibers were treated with a silane coupling agent to improve interfacial bond between alumina fibers and polymer resin matrix. The aligned specimen demonstrated improvement in tensile strength with increasing nanowire content and their alignment.A hexagon shaped acoustic tweezer was incorporated into the stereolithography device to pattern conductive micro- and nanoparticles. This new approach for particle microstructuring via acoustic aligning during the stereolithography was used to produce embedded conductive microstructures in 3d printed parts. The acoustic tweezer was used to pattern the conductive particles into horizontal, 60°, and 120° parallel striped lines. The influence of the particle percentage content onto the electrical resistivity and thickness of the patterned lines were also investigated for different materials such as copper, magnetite, and carbon fiber. The copper patterns show less resistance to electrical currents compare to magnetite and carbon nanofiber patterns. Additionally, the influence of the particle concentration to the height of the pattern was studied and the data was utilized to achieve conductivity along z-axis. Later, this approach was used to fabricate examples of embedded conductive complex 3D microstructures

The impact of psychological empowerment dimensions on job performance and mediating role of organizational commitment: An empirical study

Bu çalışmada iş performansına olumlu etkileri olduğu düşünülen psikolojik güçlendirme ve örgütsel bağlılık kavramları ele alınmıştır. TRB-2 Bölgesinde (Van, Hakkâri, Bitlis, Muş) kamuda eğitim sektöründe çalışanların katılımıyla (n=437) yapılan analizler neticesinde psikolojik güçlendirme boyutlarının (anlam, yetkinlik, etki, özerklik) iş performansını pozitif yönlü ve anlamlı olarak etkilediği tespit edilmiştir. Ayrıca örgütsel bağlılığın iş performansını pozitif yönlü ve anlamlı olarak etkilediği görülmüştür. Örgütsel bağlılığın, psikolojik güçlendirmenin alt boyutlarıyla iş performansı arasındaki ilişkide aracılık rolü oynadığı belirlenmiştir.In this study, the psychological empowerment and the organizational commitment concepts, known to be influential on job performance, are scrutinized. The data are collected from educational public employees (n=437) in TRB-2 region (Van, Hakkâri, Bitlis, Muş) of Turkey. It is found that the dimensions of psychological empowerment (meaning, competency, impact and autonomy) significantly and positively affect job performance and affective organizational commitment has a significant and positive impact on job performance while normative and continuance organizational commitment do not have. A significant and positive partial mediating role of organizational commitment on the association between psychological empowerment and job performance is revealed

Investigation of Attitudes of University Students towards Turkish Language Course and Distance Education

Turkish language course in Turkish higher education is compulsory for all programs. Being taught for two semesters, this course has started to be given in many universities through distance education in recent years. This new situation brings about the problem as to whether there is a relationship between attitude towards distance education and attitude towards Turkish language lesson. It was aimed in this study to examine and compare the attitudes of university students who take Turkish Language courses through distance education towards this course and distance education system in terms of various variables. In this descriptive research, a survey model was used to obtain data. The study group consists of the 181 freshmen attending a state university located in the south of Turkey and taking Turkish language lessons in the 2018-2019 academic year. Data were collected with attitude scales whose validity and reliability was tested. Difference tests between means were performed in data analysis. It was concluded in the study that the attitude of undergraduate freshman students towards Turkish Language course and distance education is above average, but not very high. It can also be foreseen according to findings of this study that university students' attitudes towards Turkish language course will improve as their attitudes towards distance education increase

Effects Of Different Irrigation Regimes On Water Use And Vegetative Growth Parameters Of Almond Trees

Farklı sulama suyu uygulamalarının badem ağaçlarının su kullanımı ve vegetatif gelişme parametrelerine etkilerinin araştırıldığı çalışma, 2014 ve 2015 yıllarında Tekirdağ koşullarında yürütülmüştür. Araştırmada, A sınıfı buharlaşma kabından ölçülen buharlaşma değerlerinin %50, 75 ve 100’ ünün uygulandığı üç farklı sulama suyu uygulaması gerçekleştirilmiştir. Araştırma sonucunda, deneme konularında ölçüm periyodu boyunca ölçülen bitki su tüketimi değerleri uygulanan sulama suyu miktarlarına bağlı olarak 2014 yılında 256.45 ile 299.72 mm, 2015 yılında ise 325.82 ile 396.76 mm arasında değişmiştir. Uygulanan sulama suyu miktarı arttıkça ölçülen bitki su tüketimi değerleri artmıştır. Araştırmada ayrıca farklı sulama suyu uygulamalarının badem ağaçlarının vegetatif gelişme parametrelerine olan etkisi de irdelenmiştir. Bu değerlere göre hazırlanan varyans analiz sonuçlarında, uygulanan sulama suyu miktarlarının badem ağaçlarının vegetatif gelişme parametrelerini istatistiksel olarak etkilemediği sonucuna varılmıştır.The experiment was conducted during the growing season of 2014 and 2015 to evaluatethe water use and vegetative growth parameters of almond trees under different irrigation water levels. The three different irrigation water levels applied based on the ratio of Class A pan evaporation as 50, 75 and 100% were created in the research. As a result of this study, the seasonal evapotranspiration in the treatments during the measurement period varied from 256.45 and 299.72 mm in 2014 and from 325.82 and 396.76 mm in 2015 depending on the irrigation water applied. The measured evapotranspiration increased with increasing amout of water. The effect of the vegetative growth parameters of almond trees was also examined under the different irrigation levels. According to statistical analyses, the different irrigation levels did not affect the almond trees vegetative growth parameters, statistically

An overview of the existing and future state of the art advancement of hybrid energy systems based on PV-solar and wind

Increasing solar and wind power use in existing power systems could create significant technical issues, especially for grids with poor connectivity or stand-alone systems needing more adequate storage capacity. This is due to the unpredictable and intermittent nature of solar and wind power. The intermittent nature of solar and wind resources can be reduced by integrating them optimally, making the entire system more reliable and cost-effective to operate. The advantages and disadvantages of hybrid wind and solar energy integration systems are discussed in this research. The impact of voltage and frequency oscillations and harmonics is amplified in weak grids, affecting both grid-connected and stand-alone systems. This may be fixed by ensuring that hybrid systems are well designed, equipped with cutting-edge quick reaction control capabilities, and optimized. This review offers an overview of existing advances in PV-solar and wind-based hybrid energy systems while exploring potential future developments. Further, this review also provides an overview of the primary studies published on optimum design considerations for compactness, topologies for power electronics, and control. As the global energy environment shifts toward sustainability and resilience, this review helps researchers, policymakers, and industry stakeholders understand, adapt, and enhance PV-solar-wind hybrid energy systems

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030