748 research outputs found

    Effect of abiotic elicitor methyl jasmonate on production of rutin in callus cultures of Abutilon hirtum L.

    Get PDF
    A significant therapeutic plant from the Malvaceae family is Abutilon hirtum (L.). It is frequently used in traditional medicine to treat a variety of illnesses. Rutin is a flavonoid molecule with commercial value that has anticancer, nutritional, and anti-ageing properties. This research project was carried out to evaluate the effect of abiotic elicitor Methyl Jasmonate (MeJA) at concentrations 0.0, 0.01, 0.02, 0.03 mmol.L-1 on accumulation of rutin by callus cultures  of  Abutilon hirtum L. after 30 days of growth on  Murashige and Skoog (MS) medium to which 2000 µg.L-1 2,4-Dichlorophenoxy acetic acid (2,4-D) + 500 µg.L-1 Kinetin (Kin) were added. The results showed that the best callus stems cultivated on MS growth medium fortified with 2000 µg.L-1 2,4-D + 500 µg.L-1 Kin, recorded the highest fresh weight of 2.887 g after four weeks. This induced callus was characterized by its friable texture. The data of rutin detection in cultures of callus obtained from stems explant of A. hirtum L., using High-Performance Liquid Chromatography (HPLC) indicated the presence of rutin in these cultures by comparison with the rutin standard samples containing a precisely known concentration of a substance for use in quantitative analysis.. Treatment with 0.03 mmol.L-1 of Methyl Jasmonate gave the best rutin amount of 5.606 mg.g-1 was much higher than the control treatment of 1.569 mg.g-1. These data clearly indicated that callus cultures are a potential continuous and constant source of rutin, as a secondary metabolite, and as an alternative to field plants

    Fabrication and characterization of porous Si and embedded porous Si for photonics application / Rihana Yusuf and Alhan Farhanah Abd Rahim

    Get PDF
    The development of nanoelectronics demands the implementation of new materials that should be Si-compatible but with enhanced electric and photonic properties for further device scaling. Si/Ge can be considered as a useful and promising material for this purpose. However in photonics, Si and Ge suffer from their poor optical properties and cannot compete with the direct bandgap semiconductors^, g GaAs). Si/SiGe nanostructures need to offer new solutions for improving the optical efficiency of the materials. Ge nanostructures have attracted world-wide attention due to their interesting quantum effects both in electronics and photonics application[l]. A variety of techniques have been employed to grow such structures, the most popular one is self-assembled growth nanometer islands in highly strained system using sophisticated Molecular Beam Epitaxy (MBE) or Low Pressure Chemical Vapor Deposition(LPCVD) techniques[2-5]. However these techniques require sophisticated machine and the cost is very high. In addition, the discovery of room temperature photoluminescence in porous silicon (PS)[6], presents a great interest in optoelectronic studies of this material. Covering or filling the pore network of a PS layer to produce a silicon nanocomposite is a promising process for new potential optoelectronics applications. Hence, there is a need to find a cost effective technique to grow a quality Ge nanostructures for photonics application. In this work, an effective and low cost method of thermal evaporation is used to fabricate the Ge nanostructure while low cost porous silicon will be utilized as the patterned substrate for the Ge nanostructure inclusion. Although there is still lack of commercially valuable Si-based active photonic devices, efficient light sources and detectors based on Si/SiGe would be a breakthrough that will open possibilities for the new systemon- a-chip to incorporate photonic devices with Si nanoelectronics. Si and Ge -based photodetectors are probably the most attractive candidate for this purpose due to possibility of integration into the logic IC chips.Hence, it is therefore of high interest to study the structural and optical characteristics of Ge nanostructure embedded inside porous silicon for effective light emission and detection

    Tp-e/QT ratio and QT dispersion with respect to blood pressure dipping pattern in prehypertension

    Get PDF
    Introduction Tp-e/QT, the ratio of the interval between the peak and the end of T wave to the QT interval, is a novel index of arrhythmogenesis. We investigate Tp-e/QT and QT dispersion (QTd) in prehypertensive and normotensive patients with different patterns of nocturnal blood pressure dipping. Patients and methods Forty-seven prehypertensive and 37 normotensive adult patients were included. Ambulatory blood pressure monitoring recording was performed and patients were considered to be dipper if nocturnal blood pressure fall was at least 10%; nondipper if it was 0-10%; and reverse-dipper if less than 0%. Tp-e, QT intervals were assessed by 12-lead ECG and Tp-e/QT was calculated using these measurements. QTd is defined as the difference between the maximum and the minimum QT interval of the 12 leads. Results Tp-e/QT was 0.22+/- 0.02 and 0.16+/- 0.01 in prehypertensives and normotensives, respectively (P< 0.001), whereas cQTd was 36.1+/- 6.8 and 27.2+/- 5.2 ms (P< 0.001). Tp-e and Tp-e/QT were the lowest in the dippers and the highest in the reverse-dippers in the prehypertensive group (Tp-e/QT dipper: 0.21+/- 0.01; nondipper: 0.24+/- 0.02; reverse-dipper: 0.25+/- 0.01; for dipper-nondipper, and dipper-reverse-dipper P< 0.05). However, in the normotensive group, dipping status had no effect on Tp-e/QT. There were no significant differences between dippers, nondippers, and reverse-dippers in terms of cQTd both in prehypertensives and in normotensives. There were no associations between left ventricular mass index and Tp-e, Tp-e/QT, and cQTd in both groups. Conclusion Tp-e, Tp-e/QT, and cQTd are increased in prehypertensives compared with normotensives. Tp-e and Tp-e/QT are associated with the dipping status in prehypertensives. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved

    Dağıtım transformatörlerinin metasezgisel algoritmalarla tasarım optimizasyonu

    Get PDF
    06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Dünyadaki pek çok ekonomi, yüksek verimli transformatörlerin kullanımını zorunlu kılan veya teşvik eden enerji verimliliği yönetmelikleri veya teşvik programları kabul etmiştir. Öte yandan, transformatör verimliliğindeki artışlar, transformatör ağırlık ve boyutunda bazen % 50 hatta daha fazla bir artışı gerektirmektedir. Transformatör endüstrisi bu nedenle gerçekten en iyi tasarımları geliştirme uğraşısı ile karşı karşıyadır. Transformatör tasarım optimizasyonu (TDO) problemi, karmaşık ve süreksiz amaç fonksiyonlu ve kısıtlı karma-tamsayılı bir doğrusal olmayan programlama problemidir. TDO'nun amacı, ulusal ve/veya ulusal standartlar ve müşteri şartnameleri uyarıca, mevcut malzemeleri ekonomik olarak kullanarak daha düşük boyut, ağırlık ve maliyet ve daha yüksek işletme performansı elde etmek üzere transformatörün tüm bileşenlerinin niteliklerinin detaylı olarak hesaplanmasıdır. Bu çalışmada TDO probleminin çözümü için beş modern metasezgisel optimizasyon algoritması uygulamasının ayrıntılı karşılaştırmalı analizi üç test vakası üzerinde gösterilmiş ve iki algoritma önerilmiştir önerilen bu algoritmaların, rassal özelliklerine rağmen, garanti edilmiş küresel yakınsama özelliklerine sahip oldukları doğrulanmıştır. Algoritmaların karşılaştırılması için pragmatik bir kıyaslama yöntemi geliştirilmiştir. Literatürde sunulan TDO yöntemleri nadiren üretimde doğrudan uygulanabilir çözümler üretir. tasarım mühendisinin genellikle teorik çözümü pratik olarak uygulanabilir bir hale dönüştürmek için ek çaba harcaması gerekir. Bu problem bu çalışmada ele alınmış ve piyasada mevcut veya üretime uygun boyutlara sahip çözümler üreten bir ayrık transformatör tasarım optimizasyon yöntemi önerilmiştir Ayrıca, amaç fonksiyonu ve kısıt hesaplamalarını azaltmak için basit bir yöntem önerilmiştir. Yöntem, önbellekleme tekniği kullanılarak arama işlemi sırasında yinelenen tasarım vektörleri için hesaplamaların atlanması esasına dayanmaktadır. Performans testleri, teorik TDO için Rekabetçi-Uyarlamalı Diferansiyel Gelişim ve Guguk Kuşu Arama, Pratik TDO için de Guguk Kuşu Arama ve Çiçek Tozlaşma algoritmaları kullanıldığında küresel optimum ve ona çok yakın sonuçlar elde edildiğini göstermiştir.Many economies in the world have adopted energy-efficiency requirements or incentive programs mandating or promoting the use of energy-efficient transformers. On the other hand, increases in transformer efficiency are subject to increases in transformer weight and size, sometimes as much as 50% or even more. The transformer manufacturing industry is therefore faced with the challenge to develop truly optimum designs. Transformer design optimization (TDO) is a mixed-integer nonlinear programming problem having complex and discontinuous objective function and constraints, with the objective of detailed calculation of the characteristics of a transformer based on national and/or international standards and transformer user and two algorithms are proposed, for which it has been verified that they possess guaranteed global convergence properties in spite of their inherent stochastic nature. A pragmatic benchmarking scheme is used for comparison of the algorithms. Transformer design optimization methods presented in the literature rarely yield solutions directly applicable in productionrequirements, using available materials and manufacturing processes, to minimize manufacturing cost or total owning cost, while maximizing operating performance. Detailed comparative analysis of the application of five modern metaheuristic optimization algorithms for the solution of TDO problem are carried out in this study, demonstrated on three test cases the design engineer usually needs to convert the theoretical solution to a practical one. This problem is addressed in this study, and a discrete transformer design optimization method is proposed which yields solutions with commercially available or productionally feasible dimensions Furthermore, a simple method is proposed to reduce the number of objective function and constraint calculations. The method is based on skipping calculations for design vectors recurring during the search process, by the use of caching technique Performance tests showed that global or near-global optimum solutions can be obtained with b6e6rl and CS for TDO, and CS and FPA algorithms for DTDO

    Development of an empirical formula for estimation of bioretention outflow rate

    Get PDF
    Urbanization of a watershed affects both surface water and groundwater resources. When impervious area increases, the excess runoff and volume of water collected at the downstream end of the watershed also increases, due to the decrease in groundwater recharge, depression storage, infiltration and evapotranspiration. Low-impact development (LID) methods have been developed in order to diminish adverse effects of excess stormwater runoff. Bioretention is one of the LID types which is used to prevent flooding by decreasing runoff volume and peak flow rate, and to manage storm-water by improving water quality. In this study, an empirical formula is derived to predict the peak outflow out of a bioretention column as a function of the ponding depth on bioretention, hydraulic conductivity, porosity, suction head, initial moisture content and height of the soil mixture used in the bioretention column. Coefficients of the empirical formula are determined by using metaheuristic algorithms. For analyses, the experimental data obtained from rainfall-watershed-bioretention (RWB) system are used. The reliability of the empirical formula is evaluated by calculating the absolute per cent error between the peak value of the measured outflow and the calculated outflow of the bioretention columns. The results show that the performance of the empirical formula is satisfactory.Keywords: bioretention, low impact development (LID), excess runoff, stormwater management, empirical formul

    Teachers’ perception on the implementation of Know-Want to Know-Learned (KWL) strategy in teaching reading comprehension: A case study at Al-Ihsan Islamic Boarding School Baleendah Bandung

    Get PDF
    In the evolving education landscape, grasping how teachers’ perception and use effective methods like the Know-Want to Know-Learned (KWL) strategy is crucial. This study addresses this need by exploring how teachers perceive and apply the KWL strategy, known for its engaging and productive learning outcomes. By understanding teachers' perception, the research fills a gap and provides valuable insights to help educators adapt teaching methods to diverse learning needs and goals. This research delves into teachers' perception of the implementation of the KWL strategy in teaching reading comprehension. The study addresses two key research questions: 1) What are teachers' perceptions regarding the KWL strategy's implementation in teaching reading comprehension? 2) What procedures do teachers follow when implementing the KWL strategy in teaching reading comprehension? The study employs a descriptive approach along with qualitative research methods encompassing interviews, observations, questionnaires, and documentation to collect data from two English teachers at Al-Ihsan Islamic Boarding School in Bandung. The research method allows for a comprehensive exploration of the teachers' practices and perceptions regarding the KWL strategy's implementation. The findings shed light on the commendable effectiveness of the KWL strategy in elevating student engagement, nurturing curiosity, and facilitating structured learning. The study highlights that students become more actively involved in their learning process through the KWL strategy. Moreover, it underscores the adaptability of the KWL strategy through innovative techniques that incorporate multimedia elements and real-world connections. This adaptability ensures its relevance across diverse teaching scenarios and enhances its impact on student learning outcomes. In conclusion, the research underscores the practical viability and versatility of the KWL strategy in the context of English language teaching. The strategy's ability to foster engagement, curiosity, and structured learning. As a recommendation, teachers across various contexts are encouraged to explore and integrate the KWL strategy as a means to enrich student learning experiences and encourage active participation in the learning process
    corecore