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Determination of optimum cure condition of the polymer modified mortars and investigation of mechanical properties under freeze-thaw effects
No full textYÖK Tez No: 361085Son yıllarda polimer teknolojisinde meydana gelen gelişmeler ile polimerlerin çimento harçlarında katkı malzemesi olarak kullanımı yaygın hale gelmiştir. Polimer katkılar, betonun fiziksel ve mekanik özelliklerini iyileştirmektedirler. Ayrıca polimer katkılar harçların donma-çözülme direnci, asit direnci, sülfat direnci gibi dayanıklılık özelliklerini de attırarak daha uzun ömürlü bir beton elde edilmesini sağlamaktadır. Ancak polimer malzemenin polimerleşebilmesi için kuru ortama, betonun ise hidratasyonu için suya ihtiyaç duyması bu kompozitler için önemli bir sorunu teşkil etmektedir. Bu bağlamda; çalışma temel olarak iki kısımdan oluşmaktadır. Birinci kısmında farklı koşullarda kür edilen polimerle iyileştirilmiş harçların mekanik ve fiziksel özellikleri incelenerek en uygun kür ortamı belirlenmiştir. Bunun için 3 farklı polimer (SBR (Stiren Butadien Rubber), PSBR (Polycarboxylate-Stiren Butadien Rubber), SAC (Stiren Acrylik Co-Polymer)) çimento harçlarına 5 farklı oranda (%0, %5, %10, %15, %20) katılarak numuneler hazırlanmıştır. Daha sonra hazırlanan numuneler, 3 farklı kür (1. Kür: dışarıda sulama, 2. Kür: 16 saat suda 8 saat dışarıda, 3. Kür: 1 gün suda bir gün dışarıda) koşulunda 28 gün boyunca kür edildikten sonra mekanik özelliklerinin değişimi gözlemlenmiştir. İkinci kısmında ise birinci kısımda belirlenen kür koşulu ile kür edilen numunelerin donma-çözülmeye karşı dirençleri gözlemlenmiştir. Buna yönelik olarak donma-çözülme deneyleri, mevcut 3 farklı polimer malzeme, çimento hamurlarına 5 farklı oranda (%0, %5, %10, %15, %20) katılarak gerçekleştirilmiştir. Daha sonra bu numuneler 28 gün boyunca birinci kısımda belirlenen kür koşulu ile kür edildikten sonra 3 farklı donma-çözülme döngüsüne (0, 100, 200) tabi tutulmuştur. Donma-çözülme döngülerinin sonunda numunelerin mekanik özelliklerinin değişimi gözlemlenmiştir. Ayrıca polimerle iyileştirilmiş harçların fiziksel özelliklerinin değişimini gözlemlemek için petrografik özellikleri, su emme, su işleme derinliği ve birim kütleleri de incelenmiştir Çalışmadan elde edilen en önemli bulgular özetlenecek olunursa; öncelikle fiziksel özellikler dikkate alındığında, yapılan su emme ve su işleme derinliği deneylerinde, polimer katkıların numunelerin su emme oranını önemli oranda düşürdüğü ve su işleme derinliğini de yüksek oranda azalttığı tespit edilmiştir. Kür özelliklerinin incelendiği birinci aşamada elde edilen sonuçlar doğrultusunda polimerle iyileştirilmiş harçların taze halde su ile teması arttıkça mekanik özelliklerinin düştüğü belirlenmiştir. Bu sonuç doğrultusunda en uygun kür koşulu su ile temasın en az olduğu 1. Kür Koşulu olarak belirlenmiştir. Genel olarak, kullanılan polimer türlerinden SBR ve PSBR, harçların özellikleri üzerinde olumlu bir etki gösterirken, SAC ise tüm şartlar altında olumsuz sonuçlar göstermiştir. Polimerle iyileştirmenin harçların basınç dayanımını bir miktar düşürdüğü, ancak özellikle eğilme ve donma-çözülme direncine olumlu katkılar sağladığı görülmüştür. 200 donma-çözülme döngüsü sonunda %15 SBR ve %20 PSBR katkılı numunelerin eğilme dayanımları katkısız numunelere göre %45-50 oranında daha yüksek çıkarak oldukça olumlu sonuçlar elde edilmiştir.Recent years, polymers have widely used as additive materials in cement mortars thanks to developments in polymer technology. Polymer additives increase the physical and mechanical properties of the concrete. In addition, polymer additives contribute concrete for durability by increasing resistance of concrete against such as freeze-thaw cycles, acid attack and sulphate attacks. However, due to the fact that polymers needs dry condition for its polymerization and concrete needs wet condition for its hydration occurs important problem for these composites. This study was constituted from two main parts. In the first part of the study, optimum cure conditions of polymer modified cement mortars are determinated by increasing mechanical and physical properties of specimens cured under different condition. For this, 3 different polymer additives (SBR (Stiren Butadien Rubber), PSBR (Polycarboxylate-Stiren Butadien Rubber), SAC (Stiren Acrylik Co-Polymer)) are added to mortars in five different ratios (0% (reference), 5%, 10%, 15% and 20%) by cement mass. Then, these polymers are cured under 3 different conditions (1. Cure condition: Watering twice a day, 2. Cure condition: 16 hours in the water - 8 hours out, 3. Cure condition: One day in the water - one day out) during 28 days, and the mechanical properties of mortars is investigated. In the second part of the study, the mortars are cured under the cure condition ascertained in first section during 28 days and freeze-thaw resistance is investigated. The mortars are prepared with 3 different polymers (SBR, PSBR and SAC) in 5 different ratios (0%, 5%, 10%, 15% and 20%) for freeze-thaw tests. Then, these mortars are cure with ascertained cure condition during 28 days and the mortars are exposed 3 different freeze-thaw cycles (0, 100 and 200). The end of freeze-thaw cycles, mechanical properties of mortars is investigated. Besides, water absorption, depth of penetration of water under pressure, specific mass and petrographic properties of mortars are investigated for observing changes in physical properties of polymer modified mortars The most important results found from the study are summarized; when considering the physical properties, polymer additives were reducing water absorption and depth of penetration of water under pressure of mortars dramatically. In the first part of the study, it is investigated that mechanical properties of polymer modified mortars decreased while increasing its water curing. According to this result, the optimum cure condition is determined as 1. Cure Condition. As a result, SBR and PSBR show positive effects on properties of mortars, on the other hand, SAC shows negative effect for all conditions. Polymer modification decreases a little the compressive strength of the mortar, however increases the flexural strength and freeze-thaw resistance of the mortars importantly. After 200 freeze-thaw cycles, mortars with 15% SBR and mortars with 20% PSBR show about 45-50% increase in flexural strength according to control samples
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
The investigation of the effect of country-specific pine honey and chestnut honey on the development of pharmaceutical form and wound healing in cream style
No full textApiterapi, arı ürünlerinin, bazı hastalıkların tedavisinde tamamlayıcı olarak kullanılmasıdır. Bu doktora çalışmasında, ülkemize özgü çam balı ve kestane balı içeren krem formülasyonlarınin geliştirilmesi ve bu formulasyonların açık yaralar üzerine iyileştirici etkilerinin belirlenmesi amaçlanmaktadır. Çalışmada, herhangi bir uygulama yapılmayan kontrol grubu (A), sadece krem taşıt maddesi uygulanan grup (B), Çam Balı kremi uygulanan grup (C) ve Kestane balı kremi uygulanan grup (D) olmak üzere 4 farklı denek grubu ile çalışılmıştır. İlk aşamada, her grupta (n=14) yer alan sıçanların sırt kısmına 10 mm çapında punch aparatı ile tam kat yara oluşturulmuştur. Oluşturulan yaraların yüzey alanını kapatacak şekilde hergün krem uygulaması yapılmıştır. Farklı gruplarda yer alan sıçanların yarısının deri örnekleri yara oluşumunu takip eden ilk 7. günde alınırken geri kalan yarısının deri örnekleri 14. günde alınarak çalışmanın sıçan uygulaması kısmı tamamlanmıştır. Alınan bu deri örneklerine; histopatoloji, hidroksiprolin ve yara iyileşme alanının belirlenmesi analizleri uygulanmıştır. Histopatolojik değerlendirme sonucuna göre, kronik yangının, kestane balı kremi uygulanan grupta kontrol grubuna göre önemli derecede azaldığı tespit edilmiştir (p<0,05). Buna ek olarak, granülasyon doku ve granülasyon dokusu/fibroblast olgunlaşması'nın da kestane balı kremi uygulanan ve 14. gün alınan deri örneklerinde, kontrol grubuna göre önemli derecede azaldığı belirlenmiştir (p<0,05). Kestane balı kremi uygulanan grubun 7.günde alınan deri örnekleri neovaskülarizasyon değerlerinin, kontrol grubu neovaskülarizasyon değerlerine göre daha düşük değerlerde olduğu gözlenmiştir (p<0,05). Ayrıca, hidroksiprolin düzeyleri çalışma grupları yönüyle değerlendirildiğinde B ve D grupları arasındaki farklılık istatistiksel açıdan önemli bulunmuştur (p<0.05). Sonuçlar bütün halinde ele alındığında, kestane balı içeren kremin yara iyileşmesi üzerine katkısının olumlu yönde olduğu belirtilmiştir. Bu çalışmadan elde edilen sonuçlar temel alınarak, ileriye dönük olarak farklı bal çeşitleri, farklı hayvan modelleriyle, doz çeşitliliği sağlayarak yeni bilimsel çalışmalar planlanabilir. Anahtar kelime: Apiterapi, çam balı, kestane balı, sıçan, yara iyileşmesiApitherapy is the supplementary usage of apicultural products during treatment of some diseases. The goal of this PhD study is, development of a cream formulation containing national honeydew and chestnut honeys and estimation of their open scar healing effects. The main four study groups (n=14) of the project are: control (A)-no treatment, only cream basic ingredients containing cream applied (B), honeydew honey cream applied (C) and chestnut honey cream applied. At first, all the analyze rats were 10mm full layer wounded from their back by punch ınstrument. Cream is applied to cover the surface area of the wounds formed every day. The derma samples from the each analyze group and rat were taken at the 7th and 14th following the creation of the scars by dividing the groups equally to two. All of the derma samples were analyzed for histopathology, hydroxyproline and healing area of the scars. According to histopathology results, chronic burnt decreased significantly in the scars treated by honeydew containing creams compared to control group (p<0,05). Additionally, it was observed that granulation tissues, granulation tissue-fibroblast maturity was also decreased significantly in the 14th day sampled dermas compared to control, respectively (p<0,05). Also, Neovascularization values of chestnut honey cream applied group were lower in the 7th day sampled dermas compared to control (p<0,05). On the top of this, there were statistical difference observed between study groups B and D in the means of hydroxyproline levels (p<0,05). Overall, the results shows that, there is a clear evidence that chestnut honey has a positive effect over scar healing. I believe that the results obtained in this study will be used as basis for many other high quality studies by application of different dosages, honeys, animal models etc. Key words: Aphyteraphy, chestnut honey, honeydew honey, rat, wound healin
Investigation of the effects of Pine and Chestnut Honey on wound healing
No full textThis study aimed to investigate the effect of creams containing pine and chestnut honey on wound healing in rats. The animals were divided into the following four groups: a control group (A), a group treated with only basic cream ingredients (B), a group treated with pine honey cream (C), and a group treated with chestnut honey cream (D). Full-thickness skin wounds were created on the back of each rat (14 per group) with a 10-mm diameter punch instrument. In each group, skin samples were taken from seven rats on day 7 and from the remaining seven rats on day 14. The effects of the creams on wound healing were assessed by histopathological examination and hydroxyproline assays. The histopathological examination showed that chronic inflammation significantly decreased in group D compared to the control group (P<0.05). Furthermore, the levels of granulation tissue and granulation tissue/fibroblast maturation in skin samples taken on day 14 were also significantly lower in group D compared to the control group (P<0.05). It was observed that the neovascularization values of skin samples taken on day 7 were lower in group D than in the control group (P<0.05). Also, the difference in hydroxyproline levels between groups B and D was statistically significant (P<0.05). The results showed that the cream containing chestnut honey had a positive effect on wound healing.Trdizi
What has been done in the fight against Varroa destructor: from the past to the present
No full textBees are the major pollinators in natural ecosystems and in the agricultural production of several crops used for human consumption. However, they are exposed to multiple stressors that are causing a serious decline in their population. We highlight a major one among them, the Varroa destructor mite (Varroa) that causes severe impacts on the health of honey bee colonies, transmitting a variety of viruses that can affect the survival ability of individual bees and entire colonies. Diagnosis and mite control methods have been intensively studied in recent decades, with many studies in different areas of knowledge having been conducted. This overview summarizes these studies with a focus on colony defense systems, biological characteristics of the parasite Varroa, diagnostic methods used to establish the infestation level of colonies, and currently used control methods.Trdizi
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