Establishment of a quality system for nuclear analytical laboratories

Comprehensive Quality Control (QC) and Quality Assurance (QA) Program is stated on the quality policy, organization, methods and records for nuclear analytical laboratories which are necessary for improvement of productivity, to upgrade the performance, credibility and reputation. The proper and complete identification of quality elements for management and technical requirements are being written in Quality Manual as well as analytical and organizational procedures and working instructions according to ISO 17025 standard. Technical ability of gamma, X-ray and a/b laboratories in the Center has been checked by participation in proficiency test, critical technical variables, and quality results. Performance of quality system has been controlled by external audit inspection, progress reports and service to clients. The present study is a framework of the model project of IAEA, coded RER/2/004, which has resulted self-sustainable accreditation from the national body, TURKAK. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Novel pH/Light‐Triggered Surface for DNA Adsorption and Release

A simple strategy for the immobilization of Cy3‐labeled single strand DNA (Cy3‐ssDNA) on a Si(001) surface and its release under control of both light and pH stimuli is presented. In order to prepare a dual pH/light‐triggered surface, positively chargeable azobenzene molecules are self‐assembled on the Si(001) surface. The surface wettability of this substrate can be changed under influence of both light and pH conditions. The substrates can be positively charged under mildly acidic conditions. The pH‐sensitive behavior of the film allows binding of Cy3‐ssDNA on the functionalized Si(001) surface through e?ective electrostatic interactions with the negatively charged polynucleotide backbone. Moreover, irradiation of the film with UVA light induces trans–cis isomerization of the azobenzene units on the surface. As a result, the binding a?nity for DNA decreases due to the changing surface hydrophilicity. In order to understand and control the reversible photoswitchable mechanism of this surface, water contact angles are measured after UVA and visible light irradiation. The release of DNA from a dual pH/light‐sensitive sample is performed using fluorescence microscopy. The results show that irradiation of the film with UVA light induces trans–cis isomerization of the photoresponsive azobenzene units; this leads to significant changes in the surface hydrophilicity and reduces the binding affinity for DNA.     

Poly(p‐phenylene methylene)‐based block copolymers by mechanistic transformation

The synthesis of poly(p‐phenylene methylene) (PPM)‐based block copolymers such as poly(p‐phenylene methylene)‐b‐poly(ε‐caprolactone) and poly(p‐phenylene methylene)‐b‐polytetrahydrofuran by mechanistic transformation was described. First, precursor PPM was synthesized by acid‐catalyzed polymerization of tribenzylborate at 16 °C. Then, this polymer was used as macroinitiators in either ring‐opening polymerization of ε‐caprolactone or cationic ring‐opening polymerization of tetrahydrofuran to yield respective block copolymers. The structures of the prepolymer and block copolymers were characterized by GPC and ¹H NMR investigations. The composition of block copolymers as determined by ¹H NMR and TGA analysis was found to be in very good agreement. The thermal behavior and surface morphology of the copolymers were also investigated, respectively, by differential scanning calorimetry and atomic force microscopy measurements, and the contribution of the major soft segment has been observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Inclusion complexes of ketoconazole with beta-cyclodextrin: physicochemical characterization and in vitro dissolution behaviour of its vaginal suppositories

Ketoconazole (KZ) is an imidazole antifungal agent which is administered topically and also orally. KZ is practically insoluble in water. Vaginal candidiasis is a common condition and up to 75% of all women have at least one episode of this infection during their lifetime. The aim of study was to prepare KZ/β-cyclodextrin (β-CD) complex to improve the physicochemical properties of KZ and to investigate the possibility of preparing vaginal suppositories with the complexes. A linear increase in KZ solubility as a function of β-CD concentration was verified using the phase-solubility diagram. The resulting diagram was classified as A_L-type, is generally related to the formation of a soluble complex. Complexes were prepared in a 1:1 molar ratio by different methods, namely freeze-drying, spray-drying, co-evaporation and kneading. Characterization of the complexes prepared was performed by practical yield %, aqueous solubility, active agent amount analyses, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffractometry (PXRD) and ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. Characterization studies provided additional evidences of complexation. The paddle method defined in USP31 was used in in vitro dissolution experiments on the prepared vaginal suppositories. It was found that solubility enhancement by preparing KZ/β-CD complexes depends on the type of the preparation method. Dissolution of KZ from complexes was found to be faster than the active agent and the commercial suppositories. This result may be attributed to the interactions between β-CD and active agent, high energetic amorphous state and decrease in the interfacial tension between insoluble active agent and dissolution media.     

Preparation of a new Cu(II)-imprinted polymer and its application for the determination of trace copper in water samples by flame atomic absorption spectrometry

A new Cu(II)-imprinted polymer has been prepared for selective solid-phase extraction of Cu(II) prior to its determination by flame atomic absorption spectrometry. Two functional monomers, 4-(methacryloylamino)benzamide and 4-vinylpyridine, formed a complex with Cu(II) ion through coordination interactions. The self-assembled Cu(II)-monomer complex was copolymerised via bulk polymerisation method in the presence of ethyleneglycoldimethacrylate cross-linker. In order to remove Cu(II) ions, the resulting polymer was washed with 1.0 M HNO₃ and then with water until obtaining a neutral pH. The ion imprinted polymer was characterised by Fourier transform infrared. The experimental conditions were optimised for solid-phase extraction of Cu(II) using a column of ion-imprinted polymer (IIP). Quantitative retention was achieved between pH 5.0 and 7.0, whereas the maximum recovery for the non-imprinted polymer (NIP) was about 74% at pH 7.0. The IIP showed higher selectivity to Cu(II) in comparison to the NIP. The IIP also exhibited excellent selectivity for Cu(II) in the presence of other metal ions. The relative standard deviation and limit of detection (3s) of the method were 1.6% and 1.8 µg L^?1, respectively. The method was verified by analysis of two certified reference materials (CWW-TM-D and SRM 3280) and then applied to the determination of Cu(II) in seawater and lake water samples and haemodialysis concentrates.     

Measurement of absolute intensity of 1001 keV gamma-ray of 234mPa

The sorption behavior of ²³⁵U fission fission products ⁹⁹Mo and ¹³²Te was studied through batch and dynamic experiments when they were dissolved in 1 to 7M HNO₃ solutions. It was found that ⁹⁹Mo is always totally adsorbed on hydrated SnO₂, while ¹³²Te is rather weakly adsorbed, therefore they can be separated from each other although ¹³²Te in the solution still remains contaminated with other radionuclides as well as ⁹⁹Mo does in the solid.