Alkol-su karışımlarının durulma sürelerinin zaman boyutlu NMR tekniği ile incelenmesi

Nuclear magnetic resonance (NMR) is important technique to probe the molecular dynamics of alcoholwater mixtures by measuring their spin-lattice (T1) and the spin-spin relaxation time (T2). In this work,we used two different proton NMR devices to measure relaxation times: Bruker Minispec mq-20 timedomain NMR and 42MHz Magritek Spinsolve high-resolution NMR. T1 and T2 of the ethanol-water andmethanol-water mixtures measured for changing concentrations from pure water to pure alcohol. Theresults obtained by both devices are similar with each other. The minimal values of both relaxationparameters are observed at volume fractions of ethanol-water and methanol-water mixtures 43% and44%, respectivelyNükleer manyetik rezonans (NMR), spin örgü (T1) ve spin-spin (T2) durulma zamanları ölçümleri sayesinde alkol-su karışımlarının moleküler dinamiği konusunda önemli bilgiler vermesinden dolayı önemli bir tekniktir. Bu çalışmada, durulma sürelerini ölçmek için iki farklı proton NMR cihazı kullanılmıştır: Bruker Minispec mq-20 zaman boyutlu NMR ve yüksek çözünürlüklü 42MHz’lik Magritek Spinsolve NMR. Etanol-su ve metanol-su karışımlarının T1 ve T2 değerleri, saf sudan saf alkole kadar değişen konsantrasyonlarda ölçülmüştür. Her iki cihaz tarafından elde edilen sonucun birbiriyle aynı eğilimde olduğu açıkça görülmektedir. Elde edilen etanol-su ve metanol-su karışımlarının hacimsel oranları sırasıyla 43% ve 44% olduğunda her iki tip durulma zamanlarında minimum gözlemlenmektedir

Advanced alveolar echinococcosis disease associated with Budd–Chiari syndrome

AbstractIntroductionAlveolar echinococceal disease of the liver is rare. Echinococcus multilocularis is responsible for the development of the related clinical conditions. Advanced disease may result with serious complications such as end stage liver disease and Budd–Chiari syndrome.Presentation of caseIn this presentation, a 28 years-old woman who was a case with advanced alveolar echinococcosis complicated with a Budd–Chiari syndrome and was performed successful living donor liver transplantation, has been demonstrated with clinical and radiological images.DiscussionInitially there may be no clinical evidence of the disease in humans for years. Severity and fatality are the significant characteristics of the natural history. Extension to the surrounding tissues and metastasis of the parasitic mass may be observed. Prevention is essential in disease control. Serologic assay may identify the parasite. However, early diagnosis is rare. Staging is based on radiologic imaging. Some patients with advanced disease may require surgery. Hepatic resection and liver transplantation are accepted procedures in selected patients.ConclusionThe importance of early diagnosis to prevent advanced complications such as development of Budd–Chiari syndrome and metastasis has been underlined

CLP1 Founder Mutation Links tRNA Splicing and Maturation to Cerebellar Development and Neurodegeneration

SummaryNeurodegenerative diseases can occur so early as to affect neurodevelopment. From a cohort of more than 2,000 consanguineous families with childhood neurological disease, we identified a founder mutation in four independent pedigrees in cleavage and polyadenylation factor I subunit 1 (CLP1). CLP1 is a multifunctional kinase implicated in tRNA, mRNA, and siRNA maturation. Kinase activity of the CLP1 mutant protein was defective, and the tRNA endonuclease complex (TSEN) was destabilized, resulting in impaired pre-tRNA cleavage. Germline clp1 null zebrafish showed cerebellar neurodegeneration that was rescued by wild-type, but not mutant, human CLP1 expression. Patient-derived induced neurons displayed both depletion of mature tRNAs and accumulation of unspliced pre-tRNAs. Transfection of partially processed tRNA fragments into patient cells exacerbated an oxidative stress-induced reduction in cell survival. Our data link tRNA maturation to neuronal development and neurodegeneration through defective CLP1 function in humans

Granüler magnetik filmlerde ferromagnetik rezonans (FMR) incelemeleri

ÖZETGRANÜLER MAGNETİK FİLMLERDE FERROMAGNETİK REZONANS (FMR) İNCELEMELERİNano yapıdaki manyetik malzemeleri sentezlemek için en verimli metotlardan biri farklı dielektrik içerisine metal iyonların implantasyonudur. Bu çalışmada nanogranüler metal-polimer kompozitlerinin manyetik özellikleri ferromanyetik rezonans (FMR) tekniği ile incelendi. Polimid (PI), polietilen teraftalat (PET) malzeme içerisine yüksek dozda kobalt ve demir iyonları ile implante edilen örnekler (Doç. Dr. Rustam Khaibullin -Kazan Fizik-Teknik Enstitüsü, Rusya- hazırladı) sentezlenmiştir. 40 mm kalınlığındaki PI ve PET örnekleri iyon akım yoğunluğu 4 mA/cm2 doz aralığı (0.25-1.50)´1017 iyon/cm2 enerjisi 40keV olan Co+ ve Fe+ iyonları ile implant edildi. PI için extra üç örnek sabit dozda (1.25´1017 iyon/cm2) fakat farklı akım yoğunluğunda 4, 8, 12 mA/cm2 hazırlandı. Polimid örnekleri yaklaşık ~10-6 Torr basınç altıdaki vakumda 2 saat süresince T=300 oC sıcaklığında tavlandı. Tavlanmadan önceki ve tavlandıktan sonraki PI örneklerleriyle çalışıldı. İyon implantasyonun etki parametreleri ve termal tavlamadan sonra filmlerin manyetik ve yapısal özellikleri incelendi.Yaklaşık 70 nm kalınlığındaki polimer tabakasındaki granüler kobalt ve demir formasyonunun metal implantasyon sonuçlarını TEM incelemeleri gösterdi. Polimid örneklerindeki kobalt ve demir granüllerinin ortalama enine büyüklükleri doza bağlı olarak 10-20 nm ve 25-150 nm arasında değişmektedir. Polimid örneklerinin tavlanması kobalt ve demir granüllerin birleşmesine ve onların enine boyutlarının büyümesine neden olduğu belirlenmiştir. PET filmleri için demir nanoparçacıklarının ortalama enine büyüklükleri doza bağlı olarak 5-100 nm arasında değişmekte olup nanoparçacıklarının alan yoğunluğu demir dozuyla artmaktadır.Manyetik Resonans çalışmaları Bruker EMX serisi ESR spektrometresi ile X- band (9.8 GHz) da yapıldı. Kobalt implant edilen tavlanmamış PI örnekleri için bir FMR sinyali bulunmadı. Ferromanyetik Resonans (FMR) sinyalleri kobalt için 0.50´1017 iyon/cm2, demir için 0.25´1017 iyon/cm2 den yüksek dozdaki tavlanmış PI örneklerinde gözlendi. Ferromanyetik Rezonans (FMR) sinyalleri 0.15´1017 iyon/cm2 dozu hariç demir implant edilen tavlanmamış PET örneklerinde gözlendi. Efektif mıknatıslanma değerleri oryantasyona bağlı olarak FMR den hesap edildi. FMR absorpsiyon şiddetleri spektraların numerik integrasyonu ile tahmin edildi. Bunların sonucunda doz aralığı (0.25-1.50)´1017 iyon/cm2 olan PI ve PET örnekleri için implantasyon dozuna karşı efektif mıknatıslanma ve sinyal şiddet grafikleri elde edildi. Çalışılan filmler için efektif mıknatıslanma değerlerinin sinyallerin şiddetleri ile bir uyum içerisinde olduğu gözlendi. İmplantasyon dozunun ve akımının fonksiyonu olarak sentezlenmiş kompozitlerin manyetik özellikleri, aynı zamanda tavlama işlemi sonucunda onların modifikasyonu tartışıldı. PET örnekleri için efektif mıknatıslanma ve FMR absorpsiyon şiddetinin implantasyon dozuna bağlı olduğu 1.00´1017 iyon/cm2 dozunda perkolasyon geçişi gözlendi. Aynı doz değerinde minimum DC direnç değeri elde edildi buda perkolasyon geçişi için dipolar değişimden çok değiş-tokuş (RKKY gibi) etkileşim mekanizması ile temsil edilmektedir.Haziran, 2004 Cengiz OKAYABSTRACTFERROMAGNETİC REZONANCE (FMR) İNVESTIGATIONS OF GRANULAR MAGNETİC FİLMSThe implantation of metal ions in various hosts is one of efficient methods to synthesize the nanostructured magnetic materials. In this work magnetic properties of nanogranular metal-polymer composites have been investigated by ferromagnetic resonance (FMR) technique. The samples (prepared by Assoc. Prof. Dr. Rustam Khaibullin, Kazan Physical-Technical Institute, Russia) were synthesized b? the high dose implantation of cobalt and iron ions in polyimide (PI), polyethylene terephthalate (PET) material. The 40 mm thick PI and PET foils were implanted with 40 keV Co+ and Fe+ ions in dose range of (0.25-1.50)´1017 ions/cm2 at ion current density 4 mA/cm2. Three additional samples were prepared for PI at fixed dose (1.25´1017 ions/cm2) but varied ion current densities of 4, 8, 12 mA/cm2. Polyimide samples were annealed at the temperature T = 300 oC for 2 hours in vacuum with residual pressure of about ~10-6 Torr. Both as-implanted and post-annealed PI samples were studied. Influence of the parameters of ion implantation and subsequent thermal annealing on the magnetic and structural properties of the films was investigated. TEM investigations showed that the metal implantation results in formation of cobalt and iron granules in the irradiated polymer layer with the thickness of about 70 nm. The mean lateral size of cobalt and iron granules in PI samples varies depending on dose within 10-20 nm and 25-150 nm, respectively. It was established that annealing of polyimide samples induces coalescence of the cobalt and iron granules and increase of their lateral sizes. The mean lateral size of iron nanoparticles for PET films varies within 5-100 nm depending on dose and areal density of the nanoparticles increases with the iron dose. Magnetic resonance studies were performed with ESR spectrometer of Bruker EMX series at X-band (9.5 GHz). No signals were found for non-annealed cobalt implanted PI samples. The signal of Ferromagnetic Resonance (FMR) was observed in the annealed PI samples with doses higher than 0.50´1017 ions/cm2 for cobalt and 0.25´1017 ions/cm2 for iron. Ferromagnetic Resonance (FMR) signals were observed for as-prepared Fe implanted PET foils excepting the lowest dose of 0.15´1017 ions/cm2. The values of the effective magnetization were extracted from the FMR dependencies on orientation. The FMR absorption intensities were estimated by numerical integration of the spectra. As a result, the plot of the effective magnetization and signal intensity versus implantation dose were obtained for PI and PET samples in the dose range (0.25-1.50)´1017 ions/cm2. It was observed that for the studied films the values of the effective magnetization correlate well with the signal intensities. The magnetic properties of the synthesized composites as a function of implantation dose and current, as well as their modification due to annealing treatment were discussed. The percolation transition at the implantation dose of 1.0´1017 ions/cm2 is observed in the dose dependencies of the FMR absorption intensity and the effective magnetization for PET samples. The minimum in DC resistance found at the same dose indicates that an exchange-mediated (RKKY-like) interaction rather than the dipolar one is underlying mechanism for the percolation transition.June, 2004 Cengiz OKA

Optical and magnetic properties of Ni-implanted and post-annealed ZnO thin films

Single-crystalline ZnO thin films have been grown on sapphire substrates and implanted by 40 keV Ni+ ions with a dose of 0.25-1.25x10(17) ions/cm(2). After implantation the samples have been annealed at T=1000A degrees C for 30 minutes in air. Both as-prepared and annealed nickel-implanted ZnO samples have been investigated by ferromagnetic resonance (FMR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and optical techniques. SEM studies reveal that the surface of non-implanted ZnO thin film is very smooth, while microcracks are present in the Ni-implanted ZnO samples. Annealing after implantation recovers the surface of the implanted ZnO. Energy dispersive X-ray spectroscopy shows that the Ni concentration increases with increasing the implantation dose. Optical measurements of the Ni-implanted ZnO thin films indicate that annealing results in formation of a new phase. This phase is attributed to NiO that appears due to redistribution and oxidation of the implanted Ni ions in the ZnO matrix. Magnetic measurements show that both as-implanted and annealed samples exhibit room-temperature ferromagnetism. VSM data indicate that annealing procedure results in decreasing the magnetic moment per Ni atom and higher coercivity at low temperatures. Magnetic-resonance studies reveal highly anisotropic FMR signal in the as-implanted Ni:ZnO samples starting from the dose of 0.5x10(17) ions/cm(2). We also observe a step-wise increase of the effective magnetization at the dose of 1.0x10(17) ions/cm(2), which is explained by magnetic percolation of the Ni nanoparticles. Narrow resonance signals with unusual angular dependence are observed in magnetic-resonance studies of the annealed Ni:ZnO samples, which have been related to the formation of a system of non-percolated NiO-coated Ni nanoparticles as a result of annealing in air. We did not observe experimental evidence for intrinsic ferromagnetism in the Ni-implanted ZnO thin films

Magnetic Resonance Study of Fe-Implanted TiO2 Rutile

Single-crystal (100) and (001) TiO2 rutile substrates have been implanted with 40 keV Fe+ at room temperature with high doses in the range of (0.5-1.5) x 10(17) ions/cm(2). A ferromagnetic resonance (FMR) signal has been observed for all samples with the intensity and the out-of-plane anisotropy increasing with the implantation dose. The FMR signal has been related to the formation of a percolated metal layer consisting of close-packed iron nanoparticles in the implanted region of TiO2 substrate. Electron spin resonance (ESR) signal of paramagnetic Fe3+ ions substituting Ti4+ positions in the TiO2 rutile structure has been also observed. The dependences of FMR resonance fields on the DC magnetic field orientation reveal a strong in-plane anisotropy for both (100) and (001) substrate planes. An origin of the in-plane anisotropy of FMR signal is attributed to the textured growth of the iron nanoparticles. As result of the nanoparticle growth aligned with respect to the structure of the rutile host, the in-plane magnetic anisotropy of the samples reflects the symmetry of the crystal structure of the TiO2 substrates. Crystallographic directions of the preferential growth of iron nanoparticles have been determined by computer modeling of anisotropic ESR signal of substitutional Fe3+ ions

Ferromagnetic resonance investigations of cobalt-implanted polyimides

Co+ ions of 40keV were implanted in thin polyimide foils with doses in the range of (0.25-1.50) x 10(17) ions/cm(2) at ion current densities of 4, 8 and 12muA/cm(2). The cobalt-implanted polymer foils were annealed at a temperature of 300degreesC for 2h in vacuum. Both the as-implanted and post-annealed samples were investigated by the ferromagnetic resonance (FMR) technique supplemented by transmission electron microscopy (TEM). TEM investigations showed that the implantation results in the formation of cobalt granules in the irradiated polymer layer with the thickness of about 70 nm. The mean lateral size of cobalt granules varied within 5-20 nm depending on the dose. The annealing of the implanted samples induced coalescence of the cobalt granules and increase of their lateral sizes. No FMR signals were found for the as-prepared polymer foils implanted by cobalt ions at low current density of 4 muA/cm(2). FMR signals were observed for the as-prepared samples implanted at higher ion current densities of 8 and 12 muA/cm(2) as well as for all annealed samples. The values of the effective magnetisation were extracted from the FMR spectra measured at different sample orientations in the applied magnetic field. Dose dependencies of the FMR absorption intensity and effective magnetisation were obtained for the annealed films. The magnetic properties of the synthesised cobalt-polymer composite materials and their modification due to the annealing treatment are discussed. (C) 2003 Elsevier B.V. All rights reserved