New solvents for surfactant self-assembly : molten hydrated salts and concentrated aqueous electrolyte solutions

Ankara : The Department of Chemistry and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Ph.D.) -- Bilkent University, 2013.Includes bibliographical references leaves 123-136.Lyotropic liquid crystalline (LLC) mesophases are formed by at least two components: a surfactant and a solvent. Common solvents in the surfactant self-assembly include water, organic liquids, and ionic liquids. In this work, we show that molten hydrated salts of the type [M(H2O)m](X)n (where, M is a transiton metal cation and X is a suitable anion such as NO3 - , Cl- , and ClO4 - ), which have melting points close to room temperature (RT), can organize surfactant molecules into LLC mesophases. As an example, we have focused on the [Zn(H2O)6](NO3)2-C12EO10 system (where, C12EO10 is decaethylene monododecyl ether; H3C-(CH2)11-(OCH2CH2)10-OH). A binary phase diagram was constructed between -190oC and 110oC using differential scanning calorimetry (DSC), polarized optical microscopy (POM), X-ray diffractometry (XRD), fourier transform infrared spectroscopy (FT-IR), and raman spectroscopy. The phase diagram closely resembles the phase diagram of H2O-CmEOn systems, exhibiting typical phases such as spherical cubic, hexagonal, and bicontinuous cubic. It is also observed that the phase transitions are dictated by the critical packing parameter (CPP) as the solvent concentration is changed. The mesophases are unusually stable at low temperatures, where a LLC to mesostructured solid transformation has been observed with a glass transiton at - 52oC. The mesostructured solid phase is also stable at -190oC. The confinement of the salt species in the LLC domains prevents the crystallization of the salt at low temperatures. In the second part, from the analogy between [M(H2O)m](X)n type salts and concentrated electrolyte solutions of alkali metal salts, the mixtures of concentrated aqueous solutions of some Li+ salts (LiCl, LiBr, LiI, LiNO3 and LiClO4) with C12EO10 surfactant, were investigated. The mixtures exhibited LLC mesophases in a broad range of compositions. A ternary phase diagram was constructed for the LiNO3-H2O-C12EO10 system at room temperature using XRD and POM tecniques. In the LLC mesophases formed with the Li+ salts, the water remains as hydrated under ambient conditions and open atmosphere. In addition, the effect of anions on the phase behaviour follows a Hofmeister series except for the ClO4 - ion. Ionic conductivty of the LiX-H2O-C12EO10 (where X is Cland NO3 - ) mesophases has been determined in a broad range of the salt concentrations (5 to 7 salt/surfactant mole ratio) and temperature (-13 to 100oC). The LiCl-H2OC12EO10 LLC samples have also been used as a gel-electrolyte to run a polymer electrochromic device. The mesophase shows excellent performance in this device. The investigations were further extended to include some of the Ca2+ salts, namely CaCl2 and Ca(NO3)2. The concentrated aqueous solutions of both salts with C12EO10 and water exhibited LLC mesophases similar to the molten hydrated salts and concentrated solutions of Li+ salts. In the CaCl2.xH2O-C12EO10 system, an LLC to mesocrystalline phase transformation was observed, for the first time, where the salt, water and surfactant species freezes to a mesocrystalline phase at RT. Lastly, many other salt.xH2O-surfactant LLC mesophases were investigated using the following salts: NaCl, NaBr, NaI, CH3COONa, NaSCN, NaClO4, NaNO3, KNO3, KCl, KSCN, KI, MgCl2, Mg(NO3)2 and NaOH. In addition, the LLC mesophases of concentrated H3PO4 acid and C12EO10 were also investigated. Among these compounds, H3PO4 systems exhibited air stable LLC mesophases at RT and 25% relative humdity (RH). The MgCl2 system was found to exhibit air stable LLC mesophases for a couple of hours. The NaI, KSCN and NaClO4 systems were found to be stable at low salt concentrations with little or no mesostructured order. Other salt systems were unstable and leached out salt crystals rapidly. The NaOH system is unstable because of a reaction with CO2 in the air. In summary, we have found a correlation between the deliquescent relative humidity value of the salt and its LLC mesophase formation ability under ambient conditions.Albayrak, CemalPh.D

A New Technique for Simple Renal Cyst: Cystoretroperitoneal Shunt

Purpose. To evaluate the results of patient symptoms and radiologic outcomes of cystoretroperitoneal shunt (CRS) technique in the treatment of symptomatic simple renal cysts. Patients and Methods. In a prospective study, 37 patients with a simple renal cyst were treated with ultrasound-guided percutaneous CRS-catheter. Radiological success was indicated as no recurrence of the cyst or a reduction in cyst volume by at least half. Results. CRS technique was performed successfully in 36 patients with a simple renal cyst. The mean size of all cysts decreased from 8.8 cm (range 7 to 14) to 1.7 cm (range 0 to 9; P < .001). Symptomatic success (pain relief) was achieved in 29/36 (80.5%) of patients, and radiographic success was achieved in 23/36 (63.8%) of patients, with a median follow-up of 16 months (range 6 to 24). Conclusion. Ultrasound-guided percutaneous CRS technique for simple renal cysts is fast, safe, effective, and inexpensive

Investigation of two new lyotropic liquid crystalline systems : [Zn (formula) and [Zn (formula)

Ankara : The Department of Chemistry and the Institute of Engineering and Sciences of Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 85-91.The transition metal aqua complex salts (TMS) can be dissolved in oligo (ethylene oxide) type non-ionic surfactants (CnH2n+1(CH2CH2O)mOH, denoted as CnEOm) with very high salt/surfactant ratios to form lyotropic liquid crystalline (LLC) mesophases. In this study we show that addition of charged surfactants, such as cethyltrimethylammoniumbromide (CTAB) or sodiumdodecylsulfate (SDS) results a new type of LLC in which the solubility of the salts in the LC mesophase of TMS: C12EO10 is enhanced. The LC phase of a [Zn(H2O)6](NO3)2:C12EO10 is hexagonal between 1.2 and 3.2 and cubic (liquid like) above 3.2 salt/ C12EO10 mole ratios. Addition of CTAB or SDS increases the same salt/surfactant mole ratio to 8.0-9.0, which is a record salt amount for a lyotropic liquid crystalline system. The mixed surfactant mesophases have birefringent hexagonal mesophase between 2.0 and 8.0 salt/C12EO10 mole ratios The new mixed surfactant systems can also accomodate high TMSs in the presence of excessive amounts of water (35.0 water:C12EO10 mole ratio). Both systems have similar thermal properties. Izotropisation Temperature (IT) values of the new systems go down with increasing salt and charged surfactant concentrations. The mesophases are stable at high salt concentrations in the presence of high CTAB or SDS concentration in the expense of the stability of the LLC mesophase. The IT values changes from around 80o C down to 32o C with increasing composition of the LLC mesophase. The new mesophase have 2D or 3D hexagonal structure that responds to water content of the phase. A 3D hexagonal phase transforms to 2D hexagonal phase with the evaporation of excess water in both [Zn(H2O)6](NO3)2:C12EO10-CTAB-H2O and [Zn(H2O)6](NO3)2:C12EO10-SDS-H2O systems. The new mesophases were investigated using POM (Polarised optical microscope), and a hot stage under the POM, XRD (X-ray Diffraction), FT-IR (Fourier Transform Infrared Spectroscopy) and Raman techniques. These new LLC systems are good candidates for metal containing mesostructured material synthesis due to their high salt content.Albayrak, CemalM.S

Perineal üretroplastide suprapubik sistoskopi kullanımı

Objective: Posterior urethral strictures are difficult cases to treat for urologists. Anastomotic open urethroplasty is the major surgical treatment option, and various modifications/manipulations to the procedure have been recommended in the literature. We aimed to assess the advantages of performing antegrade endoscopy through the suprapubic cystostomy tract during perineal urethroplasty. Material and methods: Thirty-six perineal urethroplasties combined with suprapubic cystoscopy were performed in 33 adult male patients between 2005 and 2011. Pre-and peri-operative records of the patients were evaluated, with a particular focus on suprapubic cystoscopy findings during urethroplasty. Results: The mean patient age was 41 years, and the mean lesion length was 2.6 cm (range 1-10 cm). Lesions were secondary to pelvic trauma in 21 patients, to a history of prostatic surgery in 8 patients, and to other miscellaneous causes in the 4 remaining patients. In 23 cases with normal bladder necks, the anastomosis was created under the guidance of antegrade cystoscopy with fluoroscopy. In 10 cases, stiff guide wires or paddles were used in addition to endoscopic light to identify the correct anastomosis site. In two procedures, fistula openings were identified during endoscopy, and fistula repair was performed along with anastomosis. In one case involving the longest lesion with involvement of the bladder neck, a combined perineal-transpubic urethroplasty was performed. The mean follow up duration was 19 (3-38) months. The overall success rate was 91%, and the re-operation rate was 9%. Conclusion: Suprapubic cystoscopy is an easy-to-perform adjunctive modality in perineal urethroplasty. This method provides the benefits of supplementary endoscopic findings and feasibility of certain maneuvers that facilitate debridement and anastomosis formation concurrent with perineal urethroplasty.Amaç: Posterior üretra darlıkları ürologlar için tedavisi zor olgular arasında yer almaktadır. Cerrahi tedavide temel seçenek olan anastomotik açık uretroplasti için literatürde çeşitli manuplasyonlar ve modifikasyonlar tanımlanmıştır. Bu çalışmada perineal uretroplasti sırasında suprapubik sistostomi traktından uygulanan antegrad endoskopinin avantajlarını değerlendirmeyi amaçladık. Gereç ve yöntemler: 2005-2011 yılları arasında toplam 36 seans suprapubik sistoskopi yardımlı perineal uretroplasti operasyonu uygulanan 33 yetişkin erkek hastanın, özellikle uretroplasti sırasındaki sistoskopik bulgular başta olmak üzere, operatif verileri incelendi. Bulgular: Hastaların ortalama yaşı 41 yıl ve lezyon uzunluğu 2,6 (1-10) cm idi. Etyolojik faktör olarak 21 hastada travma, 8 hastada prostat cerrahisi, ve 4 hastada diğer nedenler saptandı. Yirmi üç olguda mesane boynu normaldi ve antegrad sistoskopun ışığı kılavuzluğunda anastomoz gerçekleştirildi. On olguda doğru anastomoz hattını saptamak için, ilaveten, sert kılavuz tellerden ve iğnelerden yararlanıldı. İki olguda endoskopi sırasında fistül saptandı ve anastomoza ilave olarak fistül onarımı uygulandı. Mesane boynunu da kapsayacak şekilde, en uzun darlığa sahip olan 1 olguda combine perineal-transpubik onarım uygulandı. Hastaların ortalama takip süresi 19 (3-38) ay idi. Genel başarı oranı %91 ve re-operasyon oranı %9 idi. Sonuç: Suprapubik sistoskopi perineal uretroplasti sırasında yararlanılabilecek kolaylıkla uygulanabilen bir yardımcı yöntemdir. Bu yöntem perineal uretroplasti sırasında debridman ve anastomoz safhalarını kolaylaştıracak destekleyici endoskopik bulgular sağlaması ve çeşitli manevralara imkan tanıması açısından avantaj sağlar

Effect of Gr Contents on Wear Properties of Al2024/MgO/Al2O3/Gr Hybrid Composites

In the present study, hybrid metal matrix composites, Al2024/10Al2O3, Al2024/10Al2O3/3MgO, Al2024/10Al2O3/6MgO, Al2024/10Al2O3/3MgO/1.5 Gr, Al2024/10Al2O3/3MgO/3Gr, and reinforcement samples (AA 2024) produced with powder metallurgy process. AA 2024 and reinforcement powders were determined mixture rations and separately mixed during 30 minutes in a three-dimensional Turbula mixer. The mixed compositions were pressed at 300 MPa and sintered at 550°C during 1 h. After that, three materials were extruded at the same temperature. Experimental results show that hybrid metal matrix composites (HMMCs) a better wear resistance than the reinforcement samples because of higher hardness. Gr behave as a lubricant during wear process. The wear resistance of HMMCs can be optimized with controlling of the reinforcement content and type