1,720,961 research outputs found
Farklı Nanopartiküller Kullanılarak Bakteri Tayinine Yönelik Gradient Yöntemi Geliştirilmesi
No full textNowadays, development of label-free, easy handling, cost-effective and fast responsive analysis methods have gained great importance. In this study, it was aimed to develop an easy handling and cost-effective nanoparticle based density gradient method intended for the pathogenic bacteria detection. To this end, unbound bacteria, bacteria captured nanoparticles and unbound nanoparticle-antibody conjugates after immunological interaction were collected depending on their density and size through the sucrose density gradient. A simple and low-cost optical system was used to measure optic density variation of the phases, and the data was processed graphically on the computer with MatLab software.
Gold nanoparticles, magnetic nanoparticles, semiconductor quantum dots and CNP, which are commonly used nanoparticles in bioassays, were utilized in the preliminary studies of density gradient centrifugation to understand the formation and shift of bacteria-particle bands in detail. Utilizing the principle of rate-zonal centrifugation was found eligible for the investigation of nanoparticle and bacteria-nanoparticle phases. The gradient parameters affecting the bacteria-particle band formation such as volume of particle solution, effect of single phase and two phase gradient, concentrations and volumes of sucrose solutions, effect of buffer solutions were investigated respectively. TEM and UV-Vis spectroscopy were used for the characterization of the nanoparticles. Fluorescence spectroscopy was used for characterization of quantum dots and FTIR-ATR was used for surface characterization of CNP. In solid media, single colonies were counted from the samples taken from gradient bands, and bacterial binding efficiencies were calculated for particle-specific and non-target interactions.
It was seen that the migration distance of quantum dot bands and dispersion of carbon sphere phases displayed differences with respect to the change in bacteria amount in the sucrose gradient. This system was calibrated with CNPs to be prepared for real sample analysis. The detection and quantification of Escherichia coli in skimmed milk were examined by the developed method. The limit of determination and limit of quantitation was determined as 8 and 28 cfu/ml, respectively. The selectivity of the method has been proven with Enterobacter aerogenes studies.
As a result, it was demostrated that rapid and sensitive bacteriological diagnosis can be performed with an easy set-up using a centrifuge and a mobile phone camera, which are easily found in almost every laboratory. The developed method that based on bacteria-NP phases for the pathogenic bacteria detection has also provided an innovative approach to centrifugation studies in the literature. In addition to this, due to cost-effective, easy handling, and having shortest response time by reducing the steps of the process; this method has become an alternative to the analysis methods in the literature.Günümüzde etiketsiz, kolay uygulanabilen, düşük maliyetli ve kısa sürede sonuç veren analiz yöntemlerinin geliştirilmesi büyük önem kazanmıştır. Bu çalışmada patojenik bakteri tayinine yönelik olarak, kolay uygulanabilir ve düşük maliyetli olan nanopartikül temelli yoğunluk gradient yönteminin geliştirilmesi amaçlanmıştır. Bu amaçla, immünolojik etkileşim sonrası bağlanmayan bakteriler, bakteri yakalayan nanopartiküller ve bakteriye bağlanmadan kalan nanopartikül-antibadi çiftleri yoğunluklarına ve boyutlarına bağlı olarak yoğunluk gradienti içerisinde farklı fazlarda toplanmıştır. Fazların optik yoğunluk değişimlerin takibi için basit ve düşük maliyetli bir optik düzenek kullanılmış, veriler MatLab yazılımı ile grafiksel olarak bilgisayarda işlenmiştir.
Biyoanaliz yöntemlerinde sıklıkla kullanılan nanopartiküllerden; altın nanopartiküller, manyetik nanopartiküller, kuantum noktalar ve karbon nanokürelerin kullanımıyla sükroz gradientinde bakteri-partikül bandı oluşumu ve bant değişimlerinin detaylı olarak anlaşılması için ön çalışmalar yapılmıştır. Nanopartikül ve bakteri-nanopartikül fazlarının incelenmesi için bölgesel santrifüj prensibinin kullanılması uygun bulunmuştur. Partikül hacmi, tek faz ve iki faz gradient etkisi, çözelti konsantrasyonları ve hacmi, tampon çözeltinin etkisi gibi band oluşumunu etkileyen gradient parametreleri ayrı ayrı incelenmiştir. Nanopartiküllerin karakterizasyonu için TEM ve UV-Vis spektroskopisi kullanılmıştır. Ayrıca kuantum noktaların karakterizasyonu için floresans spektroskopisi, karbon nanokürelerin yüzey karakterizasyonu için FTIR-ATR kullanılmıştır. Gradientteki bantlardan çekilen örneklerden katı besiyerinde koloni sayımı yapılmış, partiküllerin hedefe özgü olan ve olmayan etkileşimlerde bakteri bağlama verimlilikleri hesaplanmıştır.
Hedefe özgü olmayan etkileşimlerde bakteri miktarına bağlı olarak, kuantum nokta bantlarının göç mesafeleri ve CNP bantlarının alt sınır değerlerinin değişimi takip edilmiştir. Hedefe özgü etkileşimlerde ise bakteri-NP fazlarının ortalama optik yoğunluk değerinde bakteri miktarıyla orantılı değişim görülmüştür. Sistem CNPler ile kalibre edildikten sonra gerçek örneklerde analiz için hazır hale gelmiştir. Geliştirilen yöntem ile sütte Escherichia coli tayini yapılmıştır. Yöntemin tespit limiti ve tayin limiti sırasıyla 8 ve 28 kob/ml olarak belirlenmiştir. Enterobacter aerogenes çalışmalarıyla yönteminin seçiciliği ispatlanmıştır.
Sonuç olarak, hemen her laboratuvarda kolaylıkla bulunan santrifüj cihazı ve cep telefonu kamerası kullanılarak basit bir düzenekle, hızlı ve hassas bakteri teşhisi yapılabileceği gösterilmiştir. Patojenik bakteri teşhisi için bakteri-NP faz takibine dayanan bu yöntem literatürdeki santrifüj çalışmalarına da yenilikçi bir yaklaşım getirmiştir. Geliştirilen bu yöntem; düşük maliyetli oluşu, kolay uygulanabilnmesi, işlem basamaklarını azaltarak kısa sürede sonuç verebilmesi nedeniyle literatürdeki yöntemlere alternatif oluşturmuştur
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Effects of Electrospinning Setup and Process Parameters on Nanofiber Morphology Intended for the Modification of Quartz Crystal Microbalance Surfaces
No full textTo improve the performance of mass sensitive biosensors, the surface of a piezoelectric quartz crystal transducer, is expanded by employing electrospun nanofibers to its surface. This work describes the effect of vertical - horizontal electrospinning setups and electrospinning parameters on fiber morphology. The research objective was to obtain finer and non-beaded fiber morphologies, via controllable and repeatable process parameters, for further applications of QCM surfaces in high performance DNA-, Aptamer-, Immuno-sensor applications
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
