185 research outputs found

    Understanding the Impact of Meteorological Spatiotemporal Variability on Distant Focusing Overpressure Risk

    Get PDF
    Since the 1950s, the amplification of blast energy from explosions has been understood to be a significant hazard to public safety at launch ranges. Historically, the risk assessment of the Distant Focusing Overpressure (DFO) hazard started with a single temperature and wind profile (e.g., a radiosonde launch) as input to acoustic 1-D ray tracing models. By analyzing rays propagation and performing ray tracing, population centers under high DFO risk can be identified. Although this method is useful, less is known about how the blast waves can be focused when the spatiotemporal variability of the input profiles are considered. In summary, this work aims to consider how realistic atmospheric boundary layer variability (e.g., turbulence, land-surface contrasts) may affect blast waves propagation and focusing and, as a result, DFO risk assessment results

    Development and characterization of biodegradable biorenewable polymeric nanocomposites for food packaging applications

    Get PDF
    During the last 10 decades, plastic products have dominated humans’ lives with various applications in different fields, and particularly in food packaging industry. The fact that plastics do have numerous desirable characteristics does not conceal their detrimental effect on the environment and on human health. In order to overcome these problematic issues and to contribute to sustainable development in the future, other alternatives represented in employing biorenewable biodegradable polymers are implemented for plastics production. Poly (lactic acid) (PLA) is one of the most common employed biopolymer owing to its interesting characteristics. However, PLA exhibits poor mechanical and barrier properties. Natural plasticizers and nano-reinforcement are incorporated into PLA matrix in order to overcome its brittle nature and to improve its barrier properties, particularly for the purpose of food packaging applications. This research focused on two parts: (i) improving the toughness and flexibility of PLA by investigating the effect of addition of three different plasticizers, namely, polyethylene glycol (PEG), tri n-butyl citrate (TBC), and triacetin (TA) of different concentrations using cast solution method, and (ii) PLA/TA 10%, the best investigated combination among all in terms of mechanical properties, was then chosen as the base system to further investigate the effect of incorporating four different nano-reinforcements, namely, carbon nanotubes (CNT), COOH functionalized carbon nanotubes (CNTCOOH), graphene platelets (GNP), and COOH functionalized graphene nanoplatelets (GNPCOOH) of different concentrations for fabrication of PLA nanocomposites. The physical, chemical, and barrier properties of all prepared samples were investigated through the stress-relaxation measurements, DSC, TGA, Mercury Porosimetry, biodegradability, water absorption, oxygen permeability, and water vapour transmission. GNPCOOH nanocomposites exhibited the best mechanical behaviour among all samples, while TGA analysis revealed that it had no effect on the thermal stability. Results obtained by Hg porosimetry have shown that the total porosity has tremendously decreased by incorporation of the investigated nanofillers. The biodegradation of PLA nanocomposites in natural compost was investigated and it was observed that the incorporation of nanofillers had no specific effect on biodegradation of PLA nanocomposites. Water absorption test revealed that the functionalized nanofillers showed relative increase in water absorption as compared to pristine nanofillers. Oxygen permeability test showed that lower concentrations of GNPCOOH had higher oxygen diffusion, while higher concentrations revealed a remarkable decrease in oxygen permeability. Water vapour transmission test showed that the incorporation of nanofillers has considerably decreased the rate of water vapour transmission

    The Necessity of Continuing Professional Development for EFL Teachers

    Get PDF
          The teaching profession involves renewed work in the ever-changing and rapidly changing world of knowledge and technology. Which requires teachers to maintain the highest standards of professional practice to perform well with this innovation and rapid change. This study aimed to investigate the process through which EFL teachers become capable of engaging in, sharing control of, influencing events and in situations that affect their work as teachers. The study also aimed at investigating EFL teachers perceptions of Continuing professional development and identifying the main characteristics of existing practices, besides offering some suggestions to improve EFL teachers Continuing professional development. The study adopted the descriptive analytical method. The data was collected with a questionnaire. The sample consist of (60) EFL teachers from EL-Hasaheisa Locality. The data were analyzed with (SPSS) programme. As the  result of the analysis it is found that: Effective Continuing professional development requires time and  space, support from the Ministry of Education. Successful Continuing professional development is often grounded in teacher collaboration . The Ministry of Education does not have a budget for EFL teacher Continuing professional development. This study recommends that: The Ministry of Education should establish Continuing teachers training centres. Opportunities should be provided to teachers to participate in more activities and Continuing training. Finally the process of Continuing professional development of EFL teachers should be monitored continually

    Ventilfreie Gleichrichtermikropumpen basierend auf verzweigten Strukturen

    Get PDF
    Micropumps are key components in many Microsystems such as Lab-On-a-Chip (LOC) and Micro Total Analysis Systems (µTAS). An efficient, bidirectional, and multifunctional micropump is important to enhance the overall efficiency of any microsystem with fluid flow. Developing a bidirectional micropump with pumping and mixing capabilities will advance microsysetems technology and aid in fabricating more compact microsystems. In this work, a valve-less rectification micropump based on bifurcation geometry is designed, fabricated, and tested. Three different designs were experimentally investigated. Numerical investigation based on Lattice Boltzmann Method (LBM) was employed prior to the experimental work to numerically measure the microfluidic diodicity in conventional and non-conventional geometries at low Reynolds numbers. Softlithography and optical lithography were used to fabricate the micropumps. The working fluid and actuator were chosen to be ethanol and PZT, respectively. Moreover, the effect of the fabrication material on the micropump efficiency was investigated where two micropumps were fabricated from two different materials, PDMS and SU-8, and the testing results were compared. Additionally, the concept of valve-less rectification micropump based on a dynamic rectifying geometry was tested and verified. The results confirm the feasibility of the valve-less rectification micropump based on bifurcation geometry. Since streaming flow occurs in bifurcation structures when oscillatory flow in presence, the results of this work will lay the foundations for a micrcofluidic device that can perform two functions (bidirectional pumping and Mixing), generate streaming flow at zero-mean velocity, reliable, easy to fabricate, cost effective, compatible with wide range of working fluids and materials, capable of delivering particles-laden fluids, and self priming.Mikropumpen sind Schlüsselkomponenten in vielen Mikrosystemen wie Lab-on-a-Chip und Micro Total Analysis Systemen (µTAS). Eine effiziente, bidirektionale und multifunktionale Mikropumpe ist wichtig, um die allgemeine Effizienz von Mikrosystemen mit Fluidströmungen zu verbessern. Die Entwicklung bidirektionaler Mikropumpen, die Pumpen und Mischen können, erweitert die Möglichkeiten der Mikrosystemtechnik und ermöglicht die Herstellung noch kompakterer Mikrosysteme. In dieser Arbeit wurde eine ventilfreie Gleichrichtermikropumpe basierend auf geometrischen Verzweigungen entworfen, hergestellt und getestet. Dabei wurden drei verschiedene Designs experimentell untersucht. Vor der eigentlichen Konstruktion wurden numerische Simulationen basierend auf der Lattice Boltzmann Methode durchgeführt, um die mikrofluidische Diodizität in konventionellen und nicht konventionellen Geometrien bei niedrigen Reynoldszahlen zu messen. Zur Herstellung der Mikropumpen wurden Softlithographie sowie optische Lithographie genutzt. Als Arbeitsfluid kam Ethanol und als Aktuator PZT zum Einsatz. Der Effekt des Konstruktionsmaterials auf die Mikropumpeneffizienz wurde untersucht indem zwei Mikropumpen aus zwei verschiedenen Materialien (PDMS und SU-8) hergestellt und die Testergebnisse miteinander verglichen wurden. Zusätzlich wurde das Konzept einer ventilfreien Gleichrichtermikropumpe basierend auf einer sich selbst korrigierenden Geometrie getestet und validiert. Die Ergebnisse bestätigen die Machbarkeit einer ventilfreien Gleichrichterpumpe und bilden die Grundlage für ein mikrofluidisches Gerät, dass zwei Funktionen ausführen kann (bidirektionales Pumpen und Mischen), zudem einen Fluss bei einer Null-Durchschnittsgeschwindigkeit erzeugt, zuverlässig und einfach zu fabrizieren ist und dabei kosteneffizient und kompatibel mit einer Vielzahl von Arbeitsfluiden und Materialien ist. Die Pumpe ist selbstbefüllend und es können mit ihr partikelbeladene Flüssigkeiten gepumpt werden

    Comparison between Tris-buffer and INRA-82 extenders on the quality of chilled rabbit spermatozoa

    Full text link
    [EN] The aim of the present study was to compare the effects of tris-buffer and INRA-82 extenders on the quality of cooled rabbit spermatozoa. Pooled semen samples were collected from eight New Zealand White rabbit bucks, divided into three groups and diluted 1:5 with three different semen extenders: INRA-82, tris-citrate glucose (TCG) and tris-citrate trehalose (TCT). Following dilution, the samples were stored at 5°C for up to 48 h. Sperm motility was recorded at 24, 36 and 48 h post-cooling. Furthermore, sperm viability, morphology, membrane integrity, acrosome status and DNA integrity were assessed at 24 h post-cooling. We found that progressive motility percentages were significantly higher (P<0.05) in samples diluted in INRA-82 (61.00, 53.50, 44.00% at 24, 36 and 48 h post-cooling, respectively) than those diluted in either TCG (39.25, 32.00, 19.75%) or in TCT (47.25, 40.50, 29.00%). We also reported that sperm viability, percentage of normal spermatozoa, percentage of spermatozoa with intact acrosome and DNA integrity after 24 h cooling were significantly higher (P<0.05) in INRA-82 diluted samples compared to TCG and TCT diluted ones. In summary, our results show that dilution of rabbit semen in INRA-82 improved sperm physiological parameters post-cooling compared to those diluted in TCG or TCT. Our findings also suggest that INRA-82 is a promising diluent that can be used effectively to maintain the viability of chilled rabbit semen.Fadl, A.; Ghallab, A.; Abou-Ahmed, M. (2020). Comparison between Tris-buffer and INRA-82 extenders on the quality of chilled rabbit spermatozoa. World Rabbit Science. 28(1):13-18. https://doi.org/10.4995/wrs.2020.12287OJS1318281Agarwal A., Saleh R.A., Bedaiwy M.A. 2003. Role of reactive oxygen species in the pathophysiology of human reproduction. Fertil. Steril., 79: 829-843. https://doi.org/10.1016/S0015-0282(02)04948-8Andrabi S.M.H. 2007. Fundamental principles of cryopreservation of Bos taurus and Bos indicus bull spermatozoa. Mini review. Int. J. Agric. Biol., 9: 367-369.Batellier F., Magistrini M., Fauquant J., Palmer E. 1997. Effect of milk fractions on survival of equine spermatozoa. Theriogenol., 48: 391-410. https://doi.org/10.1016/S0093-691X(97)00250-1Batellier F., Vidament M., Fauquant J., Duchamp G., Arnaud G., Yvon J.M., Magistrini M. 2001. Advances in cooled semen technology. Anim. Reprod. Sci.,68: 181-190. https://doi.org/10.1016/S0378-4320(01)00155-5Brun J.M., Theau-Clément M., Bolet G. 2002. The relationship between rabbit semen characteristics and reproductive performance after artificial insemination. Anim. Reprod. Sci., 70: 139-149. https://doi.org/10.1016/S0378-4320(01)00197-XBustamante-Filho I.C., Pederzolli C.D., Sgaravatti A.M., Gregory R.M., Dutra Filho C.S., Jobim M.I.M., Mattos R.C. 2009. Skim milk-egg yolk based semen extender compensates for nonenzymatic antioxidant activity loss during equine semen cryopreservation. Anim. Reprod., 6: 392-399.Carluccio A., Robbe D., De Amicis I., Contri A., Russo F., Paoletti M. 2004. Artificial insemination in rabbits: laboratory and field trial with three different semen extenders. World Rabbit Sci., 12: 65-79. https://doi.org/10.4995/wrs.2004.580Castellini C. 1996. Recent advances in rabbit artificial insemination. In Proc.: 6th World Rabbit Congress,9-12 July, 1996, Toulouse, France. 2: 13-28.Daniel N., Renard J.P. 2010. Artificial insemination in rabbits. Cold Spring Harb Protoc: pdb.prot5358. https://doi.org/10.1101/pdb.prot5358Di Iorio, M. 2014. Cryopreservation of rabbit semen: effectiveness of different permeable and non-permeable cryoprotectants on post-thaw sperm quality and reproductive performances. Thesis, university of Molise, Italy.Di Iorio M., Manchisi A., Rocco M., Chrenek P., Iaffaldano N. 2014. Comparison of different extenders on the preservability of rabbit semen stored at 5°C for 72 hours. It. J. Anim. Sci., 13: 710-714. https://doi.org/10.4081/ijas.2014.3444El-Kelawy H.M., Tawfeek M.I., El-Gaafary M.N., Ibrahim H. 2012. Viability and fertilizing ability of extended rabbit semen stored at 5°C. In Proc.: 10th World Rabbit Congress, 3-6 September, 2012, Sharm El-Sheikh, Egypt. 285-289.El-Sharkawy A.A., Hattab S.A., Ghanema I., El-Garhy M.N., Soliman M.K., El-Badry D.A. 2016. Effect of different semen extenders on post-thawing activity of Arabian stallion spermatozoa. AJVS., 2:178-182. https://doi.org/10.5455/ajvs.241513Evans G., Maxwell W.C. 1987. Salamons' artificial insemination of sheep and goats (No. Ed. 2). Butterworths: Sydney, Australia.Fadl A.M. 2016. Studies on some factors affecting freezability of stallion spermatozoa. M.V.Sc. Thesis, Cairo Univ.Fadl-Aya M., Ghallab A.M., Abou-Ahmed M.M. 2019. Quality assessment of cryopreserved New Zealand white rabbit spermatozoa in INRA-82 extender containing different cryoprotectants. World Rabbit Sci., 27: 77-83. https://doi.org/10.4995/wrs.2019.10892Ghallab A.M., Shahat A.M., Fadl-Aya M., Ayoub M.M., Moawad A.R. 2017. Impacts of supplementation of semen extender with antioxidants on the quality of chilled or cryopreserved Arabian stallion spermatozoa. Cryobiology, 79: 14-20. https://doi.org/10.1016/j.cryobiol.2017.10.001Ghallab A.M., Abou-Ahmed M.M., Fadl-Aya M., Shahat A.M., El-Badry D.A., Moawad, A.R. 2019. Optimization of the Protocol for Cryopreservation of Arabian Stallion Spermatozoa: Effects of Centrifugation, Semen Extenders and Cryoprotectants. Cryo Letters, 40: 129-138.Gogol P. 1999. Cryopreservation of plasma-deprived rabbit semen. Ann. Anim. Sci., 26: 85-92.Masuda H., Nanasaki S., Chiba Y. 2004. A new extender for preservation of equine spermatozoa at +5°C. J. Equine Sci., 15 : 1-5. https://doi.org/10.1294/jes.15.1Michael A.J., Alexopoulos C., Pontiki E.A., Hadjipavlou-Litina D.J., Saratsis P., Ververidis H.N., Boscos C.M. 2008. Quality and reactive oxygen species of extended canine semen after vitamin 228 C supplementation. Theriogenology, 70: 827-835. https://doi.org/10.1016/j.theriogenology.2008.05.043Mocé E., Vicente J.S. 2009. Rabbit sperm cryopreservation: a review. Anim. Reprod. Sci., 110: 1-24. https://doi.org/10.1016/j.anireprosci.2008.08.015Palmer E. 1984. Factors affecting stallion semen survival and fertility.10th Int. Cong. on Anim Reprod and A.I., June 10-14 1984, University of Illinois, USA Vol. III, pp. 3.Partyka A., Niżański W., Ochota M. 2012. Methods of assessment of cryopreserved semen. In: Katkov II (ed) Current Frontiers in Cryobiology. In Tech Open Access Publisher, Rijeka, Croatia. 547-574. https://doi.org/10.5772/33565Roca J., Martínez S., Vázquez J.M., Lucas X., Parrilla I., Martínez E.A. 2000. Viability and fertility of rabbit spermatozoa diluted in Tris-buffer extenders and stored at 15°C. Anim. Reprod. Sci., 64: 103-112. https://doi.org/10.1016/S0378-4320(00)00185-8Rosato M.P., Iaffaldano N. 2011. Effect of Chilling Temperature on the Long-Term Survival of Rabbit Spermatozoa held Either in a Tris-Based or a Jellified Extender. Reprod. Dom. Anim., 46: 301-308. https://doi.org/10.1111/j.1439-0531.2010.01667.xRosato M.P., Iaffaldano N. 2013. Cryopreservation of rabbit semen: comparing the effects of different cryoprotectants, cryoprotectant-free vitrification, and the use of albumin plus osmoprotectants on sperm survival and fertility after standard vapor freezing and vitrification. Theriogenology, 79: 508-516. https://doi.org/10.1016/j.theriogenology.2012.11.008Sariözkan S., Tuncer P.B., Bucak M.N., Ulutaş P.A. 2009. Influence of various antioxidants on microscopicoxidative stress indicators and fertilizing ability of frozenthawed bull semen. Acta. Vet. Brno., 78: 463-469. https://doi.org/10.2754/avb200978030463Storey B.T. 1997. Biochemistry of the induction and prevention of lipoperoxidative damage inhuman spermatozoa. Mol. Hum. Reprod., 3: 203-213. https://doi.org/10.1093/molehr/3.3.203Vidament M. 2005. French field results (1985-2005) on factors affecting fertility of frozen stallion semen. Anim. Reprod. Sci., 89: 115-136. https://doi.org/10.1016/j.anireprosci.2005.07.003Vidament M., Ecot P., Noue P., Bourgeois C., Magistrini M., Palmer E. 2000. Centrifugation and addition of glycerol at 22 8C instead of 4 8C improve post-thaw motility and fertility of stallion spermatozoa. Theriogenolology, 54: 907-920. https://doi.org/10.1016/S0093-691X(00)00401-5Zhu Z., Fan X., Pan Y., Lu Y., Zeng W. 2017. Trehalose improves rabbit sperm quality during cryopreservation. Cryobiology, 75: 45-51. https://doi.org/10.1016/j.cryobiol.2017.02.00

    Emotional Analysis of Emily Brontë’s Wuthering Heights

    Get PDF
    هناك القليل من الروايات الأولى التي أثارت جدلاً كبيراً مثل رواية مرتفعات ويذرنغ التي ركزت على الصور أو الأسلوب أو الترتيبات. على الرغم من الرواية التي أزعجت الفيكتوريين وأثارت غضبهم، فإن النقاد المعاصرين يتحدثون عن جودة بنية الرواية ومعاملة إميلي برونتي الديناميكية والمدربة للمشاعر. تنشأ رواية من خلال عبقرية المؤلف، والقراء على اتصال بالعالم الذي يمكن تخيله من الروايات من خلال أسلوبه. وبالتالي، من أجل فهم النصوص الخيالية، فإن دراسة اللغة وتحليلها عن كثب شرط مهم. يستخدم الفحص العاطفي كأداة تشخيصية لمعرفة أنماط النص وأهميته. يعتمد ذلك على المعلومات الواقعية التي توضح كيفية استخدام اللغة والمفردات والبناء لتحقيق توضيح للمحتوى. &nbsp;تقدم Wuthering Heights مجموعة متنوعة من الأساليب. من حيث الأناقة والعاطفة، قدمت برونتي قبل فترة طويلة من الوقت لها شكل أكثر ملاءمة لتوضيح موضوعها وأفكارها بشكل كاف. هذه المقالة، إذن، هي محاولة للعثور على ما يلفت الانتباه إلى أسلوب برونتي العاطفي.There are few first novels that have aroused much argument such as the novel of Wuthering heights which were concentrated on images, style or arrangements. In spite of the novel has annoyed and angered Victorians, contemporary critics have been talking about the quality of the novel's structure and Emily Brontë's dynamic and trained treatment of feeling. A novel arises through the author's genius, and readers in touch with the imaginable world of novels through its style. Thus, in order to understand fictional texts, studying and analyzing language closely is an important condition. Passionate examination is utilized as a diagnostic instrument to see text patterns and their importance. It depends on factual information that demonstrate how language, vocabulary, and construction are used to achieve an elucidation of the content. Wuthering Heights offers a diversification of styles. In terms of style and emotion, long before her time, Brontë gave her a more appropriate form to illustrate her subject and her thoughts adequately. This article, then, is an endeavor to find what draws attention to Bronte's emotional style

    Physiochemical Screening,GC/MS analysis and Antimicrobial Activity(vitro test) of Volatile oil from Garden Parsley(Petrocelinum satium).

    Get PDF
    بذور نبات البقدونس تعتبر من الفصيلة الخيمية , تنمو حتى 30- 100 سنتميتر في الارتفاع هدفت الدراسة لاستخلاص الزيت من بذور نبات البقدونس و التحقيق في محتوياته, دراسة الخواص الفيزيائية و كيميائية , مكونات الزيت باستخدام GC/MS و دراسة النشاط البيولوجي. الخواص الفيزيائية و الكيميائية قدرت وفقا للمعيار البريطاني, محتوى الزيت وفق الفارما كوبيا البريطانية للتقطير المائي، ومكونات الزيت عن طريق GC/MS و النشاط البيولوجي وفقا لطريقة ( NCCLS). النتائج وضحت أن نسبة الاستخلاص 5.5% , , الكثافة 0.97جم/سم3, , معامل الانكسار 1.494, درجة اللون ( الأصفر5.1, الأحمر 4.1, الأزرق7.5), رقم الحموضة 4.067ملجمKOH/جم, رقم البيروكسيد 38ملجمO2/كجم, الرقم اليودي 80.58ملجمI2 /جم و رقم التصبن 192.84جم/كجم . تم اجراء التحليل بواسطة جهاز GC-MS و وجد أن الزيت يحتوي على42 مركب , المركبات التي تحتوي على أعلى نسبة هي: Palmatic acid (hexadecanoic acid) yielded (5.84%), , Oleic acid (9, 12, -octadecadienoic acid; (Z,Z) methyl ester) (14.45%),(9-octadecenoic acid(z)-, methyl ester) (30.55%)) Apiol (21.12%), , 1, 3Benzodioxol,4-methoxy-6-(2-propenyl)(8.63%) و Alpha-pinene (4.13%) يمكن أن نختم بأن محتويات الزيت , خواصه الفيزيائية والكيميائية و ناشطة البيولوجي كانت نسبيا مشابهة للدراسات السابقة. فصل المركبات الموجودة في زيت بذرة نبات البقدونس و دراسة المكونات المفصولة , عمل فحص كيميائي نباتي للمركبات الطبيعية في الزيت و دراسة النشاطات البولوجية الاخرى للزيت الغير متضمنه في هذه الدراسة
    corecore