Mesoscopic sponge-like topology engineered onto polypropylene promotes retention of bound protein:

The interaction between biopolymers and plastic surfaces defines an area of much interest. In this study, the oxidative activation, surface engineering and protein binding ability of polypropylene derivatives were examined. Figure 1 shows the superimposed carbonyl regions of an ATR-FTIR spectrum of polypropylene, whose surface was subjected to a timecourse oxidation. Oxidation yields increased gradually, affording a maximum signal after 18h. Three distinct carbonyl types were noted. On the basis of spectral data & established reaction chemistries, the oxidation products appeared to be limited to alcohol, ketone, carboxylic acid and potentially ester groups (Pavia et al., 1979). The SEM micrographs of figure 2 showed no significant changes of topology over the first 8h of reaction. In comparison, minor changes had developed by 10h, in the form of sparsely distributed mesoscale bulges. A brief period of dramatic change occurred thereafter, as evidenced by the sponge-like mesoscale topology at 12h. The transformation was noteworthy in that it reflected the release of material stresses, which had accumulated during reaction. When the brevity of this dramatic change was assessed against the continual accumulation of oxidation products, the underlying mechanism pointed to an oxidative phase separation (Hellan, 1984). Further oxidation (14h) did not alter the appearance. Several oxidized surfaces were treated with hydrolyzed aminopropyltriethoxysilane, yielding an aminated surface. Of these, some surfaces were reacted further with ninhydrin, yielding the corresponding aldehyde surface. Interactions between protein and each surface were assessed by the extent to which a trace-labeled fluorescent albumin derivative could be loaded and retained following several washings. A negative control surface, i.e., native polypropylene, did not retain fluorescence after the washings. In contrast, the oxidized, aminated and aldehyde-bearing surfaces retained substantial fluorescence. A related experiment was conducted using mesoscopically flat surfaces to ascertain if the sponge-like topology alone had promoted protein retention. This time, the protein-loaded aminated surfaces lost all fluorescence after the washings. In contrast, oxidized and aldehyde-pendant surfaces still retained fluorescence, presumably by forming imine bonds with protein. Thus, the contribution of a sponge-like topology proved sufficient, yet vital, to achieve retention in the absence of any covalent bonding. Zeolite-related work by Takahashi et al. (2001) gave a physical basis to rationalize protein retention along a sponge-like topology. In this model (Figure 3), surface structures are depicted to be on the order of protein size. Direct entry of protein to the base of a crevice (A) is portrayed as difficult. Instead, protein is envisaged to adsorb at the tips, where wettability is highest (B) and to migrate to the base (C). The better shape complementarity of the base is presumed to stabilize protein-surface interactions, imparting irreversibility to the process in comparison to a flat surface (i.e., scenarios D vs. E). The findings implied that the routine use of reaction-induced phase transformations could aid in the development of alternative mesoscale topologies with refined binding traits. Such chemical approaches should therefore complement established methods based on lithography, self-organization and solvent casting

Dinamik çığ tehlike değerlendirmesi için bayes ağlarının cbs'ye entegrasyonu: ukva perspektifi

Natural hazard assessments are core to risk definition and early warning systems and play a fundamental role in the prevention of major damages. Traditional hazard identification methods are static. For this reason, new information and conditions cannot be easily included in the pre-defined hazard assessments. The Bayesian Networks can be used effectively for dynamic hazard identification. In this study, a methodology based on the Bayesian Networks model is presented for dynamic avalanche hazard assessment, in which changed and renewed data can be included in the system. In the proposed methodology, the integration of the Bayesian Networks and Geographical Information Systems (GIS) is modeled in the National Spatial Data Infrastructure (NSDI) perspective. In this structure, it is possible to combine and analyze the data obtained from different sources and factors for avalanche hazard can be dynamically updated with real-time updated data and temporal hazard mapping can be produced. The proposed methodology provides a generic structure and has an attribute making it applicable for dynamic mapping studies for other disastersDoğal afetlerle ilgili çalışmalarda tehlike değerlendirmesi, risk tanımlama ve erken uyarı sistemlerinin temelidir ve büyük kayıpların engellenmesinde önemli bir rol oynamaktadır. Klasik tehlike tanımlama yöntemleri statiktir. Bu nedenle, yeni bilgi ve koşullar önceden tanımlanmış tehlike değerlendirmelerine kolayca dahil edilemez. Bayes Ağları, dinamik tehlike tanımlaması için etkin bir şekilde kullanılabilir. Bu çalışmada, değişen ve yenilenen verilerin sisteme dahil edilebildiği dinamik çığ tehlike değerlendirmesi için Bayes Ağlarına dayanan bir yaklaşım sunulmuştur. Önerilen metodolojide, Bayes Ağlarının ve Coğrafi Bilgi Sistemlerinin (CBS) entegrasyonu, Ulusal Konumsal Veri Altyapısı (UKVA) perspektifinde modellenmiştir. Bu yapıda, farklı kaynaklardan elde edilen verilerin birleştirilmesi ve analiz edilmesi mümkün olup, çığ tehlikesi için etken faktörler gerçek zamanlı güncel verilerle dinamik olarak güncellenerek zamansal tehlike haritaları üretilebilir. Önerilen metodoloji genel bir yapı sunmaktadır ve diğer afetlere yönelik dinamik harita üretimi çalışmaları için uyarlanabilir niteliktedir

Investigation The Effect Of Film Forming Amines On The Corrosion Inhibition Of Carbon Steel

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2011Bu çalışmada, kararlı durum akım-gerilim eğrileri ve elektrokimyasal impedans ölçümleri kullanılarak, karbon çeliğin korozyonunu önlemede farklı formülasyonlara sahip poliaminlerin etkileri incelenmiştir. 5 ve 11 arasında değişen pH değerleri arasında, korozyon inhibitörü olarak kullanılan farklı yapıdaki poliaminlerin varlığında ve inhibitörler olmadan korozif ortam olarak seçilen deniz suyu, dekarbonize su ve deiyonize suyunda pH değerine bağlı korozyon önleme etkileri incelenmiştir. Aynı zamanda, pH değeri 8 değerinde sabit tutularak, 3 farklı korozif ortamda 6 farklı inhibitörün korozyon önleme performansları tespit edilmiştir. Böylece değişen inhibitör yapısının farklı su kalitelerindeki etkinlikleri saptanmıştır. İlave olarak, dekarbonize sudan pH 8 değerinde elektrokimyasal impedans spektroskopisi ile elde edilen veriler ile inhibitörlerin korozyon önleme mekanizmalarını tespit etmek amacıyla adsropsiyon izotermleri oluşturulmuştur. Taramalı Elektron Mikroskobu (SEM) ile inhibitör kullanılmadığı ve inhibitör kullanıldığı durumlardaki karbon çelik malzemenin yüzeyi, yüksek enerjili elektronlarla yüzeyin taranması incelenmiştir. Deneyler sırasında, potansiyodinamik polarizasyon eğrileri ve elektrokimyasal impedans spektroskopisinin kullanıldığı elektrokimyasal ölçümler 3 elektrotlu hücrelerde gerçekleştirilmiştir. Çalışma sırasında ayrıca EIS dataları eşlenik elektrik devre modelleri oluşturularak da analiz edilmiştir. Oluşturulan devre elemanları genellikle yaygın olarak kullanılan direnç, kapasitör ve indüktör gibi elektrik devre elemanlarıdır. Elde edilen bütün veriler ile yapı / özellik ilişkine bağlı olarak en uygun korozyon inhibitörün tespiti amaçlanmıştır.In this study, the behavior of the carbon steel, in presence of different inhibitive formulations based of film forming amines of different structures, by steady-state current-voltage curves and electrochemical impedance spectroscopy measurements was studied. Sea, decarbonised and deionised water qualities were examined in absence of and with inhibitors at varying pH values from 5 to 11 in order to to observe the pH dependency of the inhibitors at corrosion inhibition. Also, at the same pH value (pH 8), 6 different inhibitors were examined at 3 different water quality in order to obtain the relationship between the inhibitor structure and inhibitor efficiency, additionally by the effect of different corrosive media. Moreover, adsorption isotherm plots were observed by using EIS data at decarbonised water at pH=8 in order to understand the corrosion inhibition mechanism. Also, surface structure of some correded carbon steel electrodes were examined by the scanning electron microscope (SEM). The electrochemical impedance spectroscopy (EIS) is one of the most effective and reliable method to extract information about electrochemical characteristics of the electrochemical system. Electrochemical measurements, including potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) were performed in a three-electrode cell. During the work, EIS data is also analyzed by fitting it to an equivalent electrical circuit model. Most of the circuit elements in the model are common electrical elements such as resistors, capacitors, and inductors. From the data obtained, it is intended to develop structure/property relations in order to find optimal corrosion inhibitors.Yüksek LisansM.Sc

Selected methods of surface engineering applied to materials science

Two approaches were developed to surface-functionalize commercially available injection molded isotactic polypropylene tubes: Non-reactive method: A novel technique, in which organosiloxane films were fabricated and anchored on low-surface-energy polymer without invoking chemical pretreatment of the surface, was developed to surface-functionalize injection molded polypropylene tubes. In envisaging a non-reactive approach, polypropylene tubes were incubated in solutions that encouraged inter-molecular chain separation of surfacepositioned polymeric chains and entry of small, monomeric silane precursors into the sub-layers. During precursor activation, the reaction conditions encouraged activated silane species potentially in and above the plastic matrix to crosslink, in principle affording a thin coating whose bulk was partially submerged and entangled within the plastic matrix. The binary network afforded, for example, polyaminopropylsiloxane entangled within polypropylene, described a system in which two interconnected polymers shared no formal covalent bonds but nevertheless were inseparable. Reactive method: In surface-engineering of injection-molded polypropylene tubes by oxidative activation, native, mesoscopically flat tubes were oxidized using aqueous ammonium peroxydisulfate. When evaluated in the context of the conditions employed for oxidation, FTIR-ATR spectral analysis indicated that the activated plastics predominantly bore carboxyl, ketone and possibly hydroxyl groups as major surface products and an approximate uniform increase of matrix-bound oxidation products up to 16 hours reaction time. Scanning electron microscopy analyses showed insignificant changes of mesoscale topology up to 8 hours reaction time, sparsely distributed bulges of approximate 400nm diameter developed by 12 hours reaction time, and a sudden and marked transformation thereafter to give the sponge-like mesoscale topology. The main mechanisms envisaged to rationalize the topology included organized pitting of the surface, oxidation-mediated phase separation, or a combination of the two. While degradative loss of polymer chains clearly pointed to the former mechanism, it by itself could not rationalize the topology, as pitting would have been anticipated gradually in time. In fact, the dramatic change of topology, which suddenly developed late in the oxidation process, could only be consistent with a phase separation. This deduction was corroborated in conducting the parallel experiment with gradually oxidized melt-blown fibers. Mesopatterning induced by oxidation described an alternative to current methods based on lithography, self-organization and solvent casting

The evaluation of color stability of monolithic zirconia after storage in different beverages

Amaç: Bu çalışmanın amacı, günlük hayatta sıklıkla tüketilen farklı içeceklerin monolitik zirkonyanın renk stabilitesine etkisini değerlendirmektir. Materyal ve Metod: Disk şeklinde (10x1.2 mm) 40 adet monolitik zirkonya örnek hazırlandıktan sonra çay, kahve, kola ve suda bekletilmek üzere dört alt gruba (n=10) ayrıldı ve 37°C’de 24 saat, 7 gün, 15 gün ve 1 ay süreyle bekletildi. İçeceklerde bekletilmeden önce ve her bekletme süresinin sonunda renk ölçümleri spektrofotometre kullanılarak CIE-Lab sistemi ile yapıldı. Veriler ANOVA ve Duncan testi ile değerlendirildi. Bulgular: İçecek türünün zirkonya örneklerinin renk stabilitesine etkisinin önemli olduğu belirlendi (p <0.001; F: 32.908). Farklı içeceklerde bekletilen örneklerin ΔE değerleri incelendiğinde; en az renk değişiminin 24 saat çayda bekletilen örneklerde, en fazla renk değişiminin 30 gün kahvede bekletilen örneklerde olduğu tespit edildi. Tartışma: Monolitik zirkonyumun renk stabilitesi klinisyenler için önemli bir göstergedir. Test edilen materyallerle tedavi edilen hastalar renk değişimi konusunda uyarılmalıdır.Aim: The purpose of this study was to evaluate the color stability of monolithic zirconia upon exposure to different beverages which were highly consumed in daily life. Materials and methods: After the preparation of 40 monolithic zirconia samples in disc form (10×1.2 mm), they were divided into four subgroups (n=10). The samples in each group immersed in tea, coffee, cola and water at 37°C for 24 hours, 7 days, 15 days and 1 month. Color measurements were performed with the CIE-Lab system using by using spectrophotometer before and after each immersion period in beverages. The data were evaluated by ANOVA and Duncan tests. Results: It was determined that beverage type had significant effect on color stability of zirconia samples (p<0.001; F: 32.908). When examined the ΔE values for samples stored in different beverages, minimum color change were detected in the samples of tea left for 24 hours and maximum color change were detected in the samples of coffee left for 30 days. Conclusions: Color stability of monolithic zirconia is an important indicator for clinicians. The patients which had been treated with the tested materials must be warned about this discolaration

Experimental Investigation of the Hyperfine Structure of Tm I with Fourier Transform Spectroscopy Part B: in the NIR wavelength range from 700 nm to 2250 nm

In this study, we investigated the hyperfine structure of 43 spectral lines of atomic thulium. We analyzed Fourier-transform spectra in the wavelength range from 700 nm to 2250 nm, which corresponds to the wavenumber range from 14300 cm-1 to 4440 cm-1, respectively. The excited thulium atoms were generated in a hollow-cathode lamp. As a result of this investigation, the magnetic-dipole hyperfine constant A of 17 fine structure levels have been determined experimentally, 14 of them for the first time. The magnetic-dipole hyperfine constant values of the three remaining levels, reported in the literature, differed significantly from the results of our determination.Comment: 12 pages, 6 gigure

Discovery of a small molecule that selectively destabilizes Cryptochrome 1 and enhances life span in p53 knockout mice

Cryptochromes are negative transcriptional regulators of the circadian clock in mammals. It is not clear how reducing the level of endogenous CRY1 in mammals will affect circadian rhythm and the relation of such a decrease with apoptosis. Here, we discovered a molecule (M47) that destabilizes Cryptochrome 1 (CRY1) both in vitro and in vivo. The M47 selectively enhanced the degradation rate of CRY1 by increasing its ubiquitination and resulted in increasing the circadian period length of U2OS Bmal1-dLuc cells. In addition, subcellular fractionation studies from mice liver indicated that M47 increased degradation of the CRY1 in the nucleus. Furthermore, M47-mediated CRY1 reduction enhanced oxaliplatin-induced apoptosis in Ras-transformed p53 null fibroblast cells. Systemic repetitive administration of M47 increased the median lifespan of p53−/− mice by ~25%. Collectively our data suggest that M47 is a promising molecule to treat forms of cancer depending on the p53 mutation

Elderly and aged asthma have different characteristics: results of a multicenter study

Background/aim: Characteristics of asthma in the elderly population is not well-known. The aim of the present study was to evaluate asthma in the elderly population, to compare disease characteristics between patients diagnosed <60 (aged asthma) and ≥60 (elderly asthma) years of age. Materials and methods: The study was a prospective, multicenter, cross-sectional type. A questionnaire was filled out to patients 60 years of age and over, that have been followed for asthma for at least 3 months. Asthma Control Test (ACT), eight-item Morisky Medication Adherence Scale (MMAS-8) was filled out, inhaler device technique was assessed. Results: A total of 399 patients were included from 17 tertiary care centers across the country. Mean age was 67.11 years and 331 (83%) were female. The age at asthma diagnosis was ≥60 in 146 (36.6%) patients. Patients diagnosed ≥60 years were older (p < 0.001), had higher education level (p < 0.001), more commonly had first-degree relative with asthma (p = 0.038), asthma related comorbidities (p = 0.009) and accompanying rhinitis/rhinosinusitis (p = 0.005), had better asthma control (p = 0.001), were using less controller medications (p = 0.014). Inhaler technique was correct in 37% of the patients with no difference in between the groups. Treatment compliance was better in elderly asthma patients (p < 0.001). In the multivariate logistic regression analysis, having well-controlled asthma (odds ratio = 1.61, CI = 1.04-2.51), and high medication adherence rate (odds ratio = 2.43, CI = 1.48-4.0) were associated with being in the elderly asthma group. Conclusion: The characteristics of asthma are different among patients aged 60 years and over which seems to be related to onset age of asthma. In our cohort, the elderly asthma patients had higher education level, and treatment adherence and asthma control was better. Patients diagnosed ≥60 years of age did not have more severe disease