The electrospun nanofibers membranes (ENMs) have gained great attention due to their superior performance. However, the low mechanical strength of ENMs, such as the rigidity and low strength, limits their applications in many aspects which need adequate strength, such as water filtration. This work investigates the impact of electrospinning parameters on the properties of ENMs fabricated from polyacrylonitrile (PAN) solved in N, N-Dimethylformamide (DMF). The studied electrospinning parameters were polymer concentration, solution flow rate, collector rotating speed, and the distance between the needle and collector. The fabricated ENMs were characterized using scanning electron microscopy (SEM) to understand the surface morphology and estimate the average fiber sizes. The membrane porosity percentage was measured using the dry-wet weight method. Also, a dynamic mechanical analyzer was used to determine the mechanical strength properties (tensile strength and Young's modulus) (DMA). The obtained results revealed that the polymer concentration and flow rate mainly affect the porosity and fiber size in ENMs. Increasing the polymer concentration improves the strength and flexibility, while the flow rate did not show a clear effect on the mechanical strength of ENMs. Both fibers collecting speed and spinning distance did not clearly impact the membrane morphology. ENMs flexibility significantly increased with increasing the collector speed and decreasing the spinning distance. Strong and flexible ENMs with small fibers can be fabricated using 10% PAN/DMF at a flow rate of 1 mL/h, collector speed of 140 rpm, and spinning distance of 13 cm.
Anger is one of the problems of scientific importance that psychologists and education scientists are interested in, especially societies and educational environments, because if a child’s anger continues to develop into violence, then it becomes an unusual behavior, and an indication of the child's lack of adaptation to his family and his environment (Moses, 2013: 4) &n
... Show MoreThe study of Terracotta in Mesopotamia is one of the important
technical topics that gave us valuable information ،whether from a
technical or cultural point of view
تصنيع الطابوق الحراري الثقيل من خامات محلية
Etude de I' espace dans un extrait de Les sequestres d' Altona de Jean
اتخذت الهند موقفاً محايداً من الحرب الروسية الأوكرانية، لما له من أبعاد سياسية واقتصادية وعسكرية مع أطراف الصراع في الحرب، وقناعتها بعدم قدرتها على التأثير فيها. فهي تربطها علاقات استراتيجية تاريخية مع روسيا، الداعمة لها سياسياً في مجلس الأمن والوسيط ضد خصومها الصين وباكستان. لذلك الهند مقتنعة بأن أوكرانيا تُعدّ مجالاً للنفوذ الروسي الذي عمل حلف شمال الأطلسي على التوسع به رغم التحذيرات الروسية. لذا أيقنت ا
... Show MoreThe research deals with a modern concept in its applications and the studies it deals with, as the concept of urban densification is one of the most recent sustainable development strategies for cities.
Studies looking at the relationship between condensation and viability show mixed results. This study sheds light on how the built environment of dense urban areas affects the perceived quality of life of the population. How to enhance acceptance of dense life is an important question to investigate.
Adopting the concept of urban densification in city planning policies to be more sustainable and livable is of great importance by achieving efficient use of urban land and limiting urban sprawl, as well as reducing the
... Show Moreمن نحن ؟ التحديات التي تواجه الهوية الامريكية
الحمدُ للهِ رب العالمين ، والصلاة والسلام على نبيه الأمين محمد r وعلى آله الطيبين الطاهرين ، وأصحابه الغر الميامين:
تعد الصورة السمعية مفهوما بيانيا نجده في البلاغة العربية واضحاً مؤثرا، مؤديا دورا جوهريا في إيصال الفكرة التي يروم الأديب إيصالها إلى المتلقي ولا تبدو السمعية واضحة إلاّ إذا نظر إليها في حالة أدبيه تهز كيان الشاعر  
... Show MoreThis study aims at recognizing Pesticides and how the process of pesticides biodegradation by microbiology took place, and the effect of environmental condition on this process. And how the research uncovered the efficiency of microbiology in the biodegradation process of pesticides, as the perfect temperature for the biodegradation process is 40 °C and humidity effect on pesticides efficiency, when high humidity reduces pesticide efficiency and the perfect acidity to increase bacteria efficiency is 7, for the incubation period, it was found during the previous studies that the best incubation period is 5-7 days, in this period the bacteria imprint on pesticides and increase biodegradation of it.
The rabid development in life and technology arouse the anxiety, stress, and fear of people. Accordingly the maladjustment and deceived conceptions appear in their behaviors which influence their selves and others.
These changes and development in society influence the university students' life, personality, thoughts and behavior. An exceeding in anxiety and fear has negative effect on everyday life activities and. negative effect on both mind and body.
The problem of the study is centered around cognitive conception anxiety of the university students.
The university students have their special importance in society and nation development, therefore many studies search in their personality and the effect of anxiety on them to fi