Silk fibroin as a novel coating material for controlled release of theophylline

The aim of this study was to explore potential use of the silk fibroin (SF) as an aqueous coating material for theophylline tablets. We have examined the film forming and coating properties of heat-treated fibroin, SF solution having different amounts of polyethylene glycol (PEG) and 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC) cross-linked SF. Heat-treated SF material possessed a brittle structure, which resulted in poor film forming and coating properties. The optimum PEG amount in SF solution was determined as 17% (by weight) for an acceptable film forming and zero order release profile. EDC cross-linked SF has shown a very good film forming and coating property with a potential for sustaining the drug release from coated theophylline tablets. Dissolution data for coated theophylline tablets were analyzed using Ritger and Peppas equation to describe the mechanism of drug release. Drug release from the EDC coated tablets followed zero-order kinetics. Release rate constants were found to be 0.26, 0.19, 0.16% min-1 for single-coated, double coated, and triple coated tablets, respectively. These results clearly demonstrated that silk fibroin has high utility as a novel aqueous coating material for controlled release products

5086-h32 alüminyum alaşımında kaynaklama parametrelerine sıcak çatlama hassasiyetinin mvt metodu ile belirlenmesi

Hot cracking is a serious problem that encounters during welding of aluminium-magnesium alloys. In the present study, solidification and liquation type of hot cracks in weld metal and the heat-affected zones of 5086-H32 aluminium alloy were investigated by using Modified Varestraint Test (MVT) with TIG-AC and TIG-DC welding. With determining the size, type and number of cracks, a relation was established between welding line energy and strain on the hot crack formation. This information was used to determine the hot crack safe parameter ranges. The hot cracking tendency as a function of applied parameters were discussed in the frame of temperature fields around the moving heat source. Moreover, the characteristic hot crack locations on the 5086-H32 MVT specimens were generalized. The results of the study indicated that the increase in line energy and strain increased the hot cracking tendency of the specified aluminium alloy. In the low line energy range, the main hot cracking mechanism is the solidification cracking which could be overcome by the use of a suitable filler material. At high line energy range, due to the increased amount of interdendritic liquid, the amount of solidification cracking decreases by healing mechanism. However, because of the enlarged-temperature-field around the weld zone, fraction of HAZ cracking increases. The comparison between the hot cracking tendencies in low and high line energies indicates that the low line energy ranges with low augmented strains resulted in hot crack safer parameters.Ph.D. - Doctoral Progra

Milletlerarası özel hukukta çocuğun aile içinde korunması

Çocuğun aile içinde korunması, velâyet hakkı sahibi ana ve babanın, velâyet hakkından doğan bazı haklarını, yetkilerini ve yükümlülüklerini yerine getirmemeleri, getirememeleri veya ağır şekilde ihlal ederek, kötüye kullanmaları halinde çocuğun yetkili makamlar tarafından alınacak “koruma tedbirleri” ile korunmasını ifade etmektedir. Çalışmamızın amacı, milletlerarası nitelikli çocuğun velâyet hakkına sahip ana ve babasından korunmasını gerektiren hallerde, kanunlar ihtilafı kurallarını incelemek ve milletlerarası usul hukukuna ilişkin meseleleri ele almaktır. Bu inceleme yapılırken öncelikle Türk maddi hukuku ve İsviçre hukukunda çocuğun yararı ilkesi çerçevesinde, velâyet kavramı, velâyetin kullanılması ve çocuğun korunmasına yönelik tedbirler ele alınmıştır. Takiben, milletlerarası özel hukuk alanında, velâyet ve çocuğun korunmasına yönelik tedbirlere uygulanacak hukuk ve konuya ilişkin milletlerarası usul hukuku meseleleri incelenmiştir. İncelememizi yaparken, 1961 tarihli Küçüklerin Korunmasında Makamların Yetkisine Uygulanacak Kanuna Dair Sözleşme, 1996 tarihli Velâyet Sorumluluğu ve Çocukların Korunması Hakkında Tedbirler Yönünden Yetki, Uygulanacak Hukuk, Tanıma, Tenfiz ve İşbirliğine Dair Sözleşme, 2201/2003 sayılı Evlilik ve Velâyete İlişkin Hususlarda Yargı Yetkisi, Yargı Kararlarının Tanınması ve Tenfizine Dair Konsey Tüzüğü ve 5718 sayılı Milletlerarası Özel Hukuk ve Usul Hukuku Hakkında Kanun’un ilgili maddeleri ayrıntılı olarak ele alınmıştır. -------------------- The phrase, “protection of the child in the family environment” expresses the protection measures to be taken against the child’s mother or father who has parental custody over a child. In terms of taking protection measures over the child, parents having right of custody have to violate their rights, authorities, and responsibilities arising from parental custody intentionally or unconsciously. The study aims to determine the rules of conflict of laws and to address the issues related to international procedural law in cases private international law deals with about protection of the child in his/her family. In this study, first of all, the concept of parental custody and responsibility and exercise of mentioned rights and responsibilities and protection measures for child in Turkish and Swiss substantive law in the scope of the principle of the best interest of the child, are discussed. Subsequently, in the field of private international law, the issues of conflict laws and the international procedural law on the issue of parental custody and protection of the child were examined. In our review, the Convention on the Applicability of the Authorities in the Protection of Minors in the 1961 Convention, the 1996 Custody Responsibility and the Convention on the Protection of Children, the Law Applicable, the Convention on Recognition, Enforcement and Enforcement, the Judicial Power in the Matters Regarding Marriage and Vigilance No: 2201/2003, The relevant provisions of the Law on the Recognition and Enforcement of Decisions of the Council and the Law No. 5718 on Private International Law and Procedural Law are discussed in detail

Siberkondriya ölçeği (Sibkö): Geliştirme, geçerlik ve güvenirlik çalışması

Objective: The aim of the current study is to develop culture specific, multidimensional and self-report Cyberchondria Scale (CS) which can be used to evaluate one’s emotional, cognitive and behavioral tendency to cyberchondria and to determine the psychometric properties of this scale. Method: The study was conducted with two different samples consisted of Internet users. To investigate the factor structure, the first sample was composed of 250 (49.6% women, 50.4% men) individuals aged between 18 and 65. The second sample in which confirmatory factor analysis (CFA) was conducted consisted of 360 (61.1% women, 38.3% men) individuals aged between 18 and 65. In addition to CS, Internet Addiction Scale (IAS), Brief Symptom Inventory (BSI) and Health Anxiety Inventory (HAI) were used in this study. Results: The exploratory and CFA revealed a five-factor structure called “Factors Increasing Anxiety”, “Compulsion/Hypochondria”, “Factors Decreasing Anxiety”, “Doctor-Patient Interaction”, “Dysfunctional Internet Use”. The model obtained by CFA represented acceptable goodness of fit values and other reliability and validity values were found to be satisfactory. Conclusion: CS could be evaluated as a valid and reliable scale which would be used in clinical and health psychology studies conducted in Turkey.Amaç: Bu çalışmanın amacı, bireyin siberkondriyaya ilişkin duygusal, bilişsel ve davranışsal yatkınlığını değerlendirmede kullanılabilecek kültürümüze özgü, çok faktörlü, öz bildirime dayalı bir Siberkondriya Ölçeği (SİBKÖ) geliştirmek, geliştirilen bu ölçeğin psikometrik özelliklerini belirlemektir. Yöntem: Çalışma, İnternet kullanabilen iki ayrı örneklem grubuyla yürütülmüştür. Ölçeğin faktör yapısının belirlendiği ilk örneklem grubunu, yaşları 18-65 arasında değişen 250 (%49.6’sı kadın, %50.4’ü erkek) kişi oluşturmuştur. Ölçeğin doğrulayıcı faktör analizinin (DFA) gerçekleştirildiği ikinci örneklem grubunu ise 18-65 yaş arasında 360 (%61.1’i kadın, %38.3’ü erkek) kişi oluşturmuştur. Çalışmada SİBKÖ’nün yanı sıra, İnternet Bağımlılığı Ölçeği (İBÖ), Kısa Semptom Envanteri (KSE) ve Sağlık Anksiyetesi Envanteri (SANKE) kullanılmıştır. Bulgular: Yapılan açımlayıcı ve DFA sonucunda, “Kaygıyı Artıran Faktörler”, “Kompulsiyon/Hipokondri”, “Kaygıyı Azaltan Faktörler”, “Doktor-Hasta Etkileşimi” ve “İşlevsel Olmayan İnternet Kullanımı” olarak adlandırılan beş faktörlü yapı elde edilmiştir. DFA’da elde edilen model uyum indekslerinin kabul edilebilir sınırlar içinde olduğu görülmüş; elde edilen diğer geçerlik ve güvenirlik değerleri de uygun bulunmuştur. Sonuç: SİBKÖ, Türkiye’de yürütülen klinik psikoloji ve sağlık psikolojisi alanındaki çalışmalarda kullanılabilecek, geçerli ve güvenilir nitelikte bir ölçek olarak değerlendirilebilir.Ankara Universit

pH- and electro-responsive characteristics of silk fibroin-hyaluronic acid polyelectrolyte complex membranes

pH-responsiveness of recently developed silk fibroin (SF) and hyaluronic acid (HA) polyelectrolyte complex (PEC) membranes and their potential use in electro-responsive drug release systems were investigated. PEC membranes were prepared within a narrow pH window (3.0-3.5) for a SF-HA weight ratio of 20 and they were characterized by Atomic Force Microscopy in addition to characterization studies previously reported by our group. Swelling kinetics of the membranes was studied for a pH window of 2.5-7.4 and cyclic swelling test was performed to determine the pH-responsiveness of the membranes. It was shown that membranes swelled more in alkaline conditions and responded to variations in pH of the medium. Electric-stimuli assisted drug permeation and release studies were performed with a custom-made diffusion cell under both passive condition and electric field applied in pulsatile fashion. The instantaneous flux raised as the current was applied and then declined when the current application was terminated, and this process was repeated on subsequent applications. SF-HA complex membranes were found promising for the electric-stimuli-sensitive release of a high molecular weight and charged model drug for a membrane-permeation controlled formulation.Izmir Institute of Technolog

The pathways from distress tolerance to cyberchondria: A multiple-group path model of young and middle adulthood samples

The use of the Internet for medical information elicited a recent term called "cyberchondria". This study aimed to scrutinize the mediating effects of health anxiety (HA), anxiety symptoms (AS), and Internet addiction (IA) in the pathway from distress tolerance (DT) to cyberchondria by using a bootstrapping method. In order to examine the role of age in the proposed model, multiple-group path analysis was used to evaluate differences between young and middle adulthood groups. The final sample consisted of both young adult (n = 209) and middle adult (n = 221) Internet users located in Ankara, Turkey. The results of path analyses for both age groups showed that DT is negatively associated with AS and HA; AS and HA are positively associated with IA; IA and HA are positively associated with cyberchondria. Mediation analysis for both age groups demonstrated that AS and HA significantly mediated the relationship between DT and IA; IA significantly mediated the relationships of AS and HA with cyberchondria; HA significantly mediated the relationship between DT and cyberchondria. The results of the multiple-group path analysis showed that the relationship between IA and cyberchondria is significantly stronger in middle adulthood than young adulthood. The results of the current study are consistent with the relevant literature and provide crucial contribution especially by focusing on the role of age.Ankara Universit

Alın Kaynaklı Yapısal Çeliklerdeki Kalıntı Dağılımının Konstrüksiyon Güvenliğine Etkisi

Plakalar arası alın dikişleri konstrüksiyon bağlantısı olarak başvurulan birleştirme türlerinden birisidir. Bu dikişler plaka kalınlığına, kaynak yöntemine ve ulaşılabilirliğe bağlı olarak farklı kaynak ağzı ve paso dizilimi ile kaynak yapılmaktadır. Gerçekleştirilen kaynak işlemi, kaynak dikişi boyunca geometri, ilk sıcaklık, ısı girdisi, tutma koşulları, soğuma koşulları vb faktörlere bağlı olarak bir kalıntı gerilme profili meydana getirmektedir. Bu bildiride MAG kaynağı uygulanmış çok pasolu bir plaka alın birleştirme işlemine ait kalıntı gerilme dağılımı incelenecektir. Takiben konstrüksiyon üzerinde alınması gereken önlemler ve konstrüksiyonun yüklenebilirliği üzerindeki kriterler tartışılacaktır

Effect of Residual Stresses on the Structural Safety of the Butt Welded Structural Steels

Butt welded seams are widely used in steel constructions. The welding conditions, bevel geometry and the weld sequence are decided by considering the material thickness, welding process and the accessibility. Welding operation generates a residual stress state in the joint area depending on the geometry or path of the weld, initial temperature of the material, heat input, clamping conditions, cooling conditions, phase transformations, etc. Design of a product ignoring residual stresses always involves risks for distortion or early failure in the service. In this work, the construction safety measures and the loading safety was discussed based on the surface residual stress distribution in the butt welded joints