THE GROWTH OF STRAINED THIN FILMS OF GADOLINIUM

The growth of strained thin films of gadolinium has been investigated with low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) and compared to the film growth of unstrained gadolinium. Strained thin films of gadolinium are distinct from the unstrained films by a substrate induced preferential domain growth direction, which is also reflected in the electronic structure

Effects of thermal annealing on the morphology of the AlxGa(1x)N films

Cataloged from PDF version of article.Effects of thermal annealing on the morphology of the AlxGa(1-x)N films with two different high Al-contents (x=0.43 and 0.52) have been investigated by atomic force microscopy (AFM). The annealing treatments were performed in a nitrogen (N-2) gas ambient as short-time (4 min) and long-time (30 min). Firstly, the films were annealed as short-time in the range of 800-950 degrees C in steps of 50-100 degrees C. The surface root-mean-square (rms) roughness of the films reduced with increasing temperature at short-time annealing (up to 900 degrees C), while their surface morphologies were not changed. At the same time, the degradation appeared on the surface of the film with lower Al-content after 950 degrees C. Secondly, the Al0.43Ga0.57N film was annealed as long-time in the range of 1000-1200 degrees C in steps of 50 degrees C. The surface morphology and rms roughness of the film with increasing temperature up to 1150 degrees C did not significantly change. Above those temperatures, the surface morphology changed from step-flow to grain-like and the rms roughness significantly increased. (C) 2009 Elsevier Ltd. All rights reserved

L-MYC gene polymorphism and risk of thyroid cancer

L-myc gene polymorphism is a representative genetic trait responsible for an individual’s susceptibility to several cancers. However, there have been no reports concerning the association between thyroid cancer and L-myc gene polymorphism. Aim: To analyze the distribution of L-myc gene polymorphism in Turkish patients with thyroid disorders and thyroid cancers. Methods: We used a molecular genotyping method, polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). We studied 138 patients of whom 47 had multinodular goiter, 13 had follicular cancer and 69 had papillar cancer, in comparison with control group of 109 healthy individuals. Results: No significant difference in the distribution of genotypes was observed between thyroid patients and controls. Carrying SS or LS genotype revealed a 1.96-fold (95% CI 0.573–6.706) risk for the occurrence of follicular cancer when compared with controls, and 3.11-fold (95% CI 0.952–10.216), when compared with multinodular goiter patients (p = 0.04). Conclusion: We suggest that L-myc genotype profiling together with other susceptibility factors, may be useful in the screening for thyroid nodular malignancy.Для ряда опухолей человека показана корреляция между риском развития опухоли и определенным вариантом гена L-MYC. Данные о наличии такой связи при раке щитовидной железы к настоящему времени отсутствуют. Цель: проанализировать распределение полиморфных типов гена L-MYC в популяции больных с доброкачественными и злокачественными поражениями щитовидной железы, включая рак щитовидной железы, в Турции. Методы: для анализа полиморфизма гена L-MYC использован метод молекулярного генотипирования, в частности, метод определения полиморфизма длины рестрикционных фрагментов, основанный на полимеразной цепной реакции (PCR-RFLP). Определение проводили в лейкоцитах 138 больных, в том числе 48 больных с узловым зобом, 13 больных фолликулярным раком щитовидной железы и 69 больных папиллярным раком. Контрольную группу составляли 109 здоровых лиц. Результаты: статистически достоверных различий в распределении исследуемых генотипов у больных с патологией щитовидной железы и здоровых лиц не выявили. Показано, что относительный риск фолликулярного рака щитовидной железы у больных-носителей генотипа SS или LS составляет 1,96 по сравнению со здоровыми лицами (при 95% доверительном интервале от 0,573 до 6,706) и 3,11 по сравнению с больными с узловым зобом (при 95% доверительном интервале от 0,952 до 10,216) (р = 0,04). Выводы: по нашему предположению, определение профиля полиморфизма гена L-MYC с учетом других факторов, определяющих предрасположенность к развитию опухолей, может быть полезным при скрининге озлокачествления узелковых образований щитовидной железы

Surface studies of magnetic thin films

Despite the resonances of the various multiplet components the dichroism signal retains a uniform spectral shape. The well-resolved multiplet structures have been obtained in 5p photoemission of Tb using circularly polarised light. This multiplet structure is caused by the interaction between the core level photohole and those partially filled subshell, i.e. as result of the unpaired 4f and 5p electrons. In 4f levels of Tb(0001) films, the well-resolved surface component of the Tb sup 8 S sub 7 sub / sub 2 has been observed a separation of magnetic circular dichroism in the angular dependence effect for the surface layer and for the bulk. Depending on the preparation procedure, new iron superstructures on W(110) substrate have been observed. The photographs of the LEED images provide information about the ordered arrangement of atoms on the surface and the distances between the spots. These LEED patterns are also an evidence of crystal structure of iron films. The sharpness of the spots gives insight on how well ordered the surface atoms are arranged. The magnetic phenomena of 25 ML Fe(110) films on W(110) substrate using magnetic circular dichroism in the angular dependence technique shows maximum asymmetry, 12%. This is the highest value compared to the previous results. Experimental results show that an effect of the magnetic circular dichroism in the angular dependence strongly depends on the magnetisation direction. It is found that the ideal magnetisation direction for circularly polarised radiation is the [110 ] direction. Reflectance anisotropy spectroscopy was for the first time applied to a clean W(110) substrate, Fe(110) films on W(110) and oxidation of the W(110) surface in real time. The simulated reflectance anisotropy based on Fresnel model provides an evidence of anisotropy behaviour of cubic W(110) surface. This study provides a new approach of analysing the surface states of cubic metals. It has been observed that RAS signal increases for thick films of Fe on W(110) compared to the thin films at around photon energy of 3 eV. This anisotropic behaviour decreases with increasing annealing temperature of the films. The surface sensitivity of reflectance anisotropy spectroscopy has been exploited when applied to a cubic single crystal to study the surface electronic structure of W(110) and the resulting chemisorption-induced changes upon exposure to oxygen. As a result of spin-resolved photoemission from 60 monolayers thick Gd(0001) films grown on W(110), the spin polarisation of the secondary electrons provides information on electron-hole excitations which produce the majority of low-energy secondary electrons. The observed direct and exchange electron-hole scattering of 4f primary electrons indicates that there are contributions to the secondary electrons from both the 4f levels and the valence band. Spin-resolved spectra of the same thickness of Gd 4f peaks show a polarisation of 35+-2%, with no significant variation across the peaks. The secondary electron polarisation, 16.5+-1.0%, is lower than that of the 4f's. The resonant behaviour of the 4f satellite peaks of Gd(0001) films grown on W(110) substrate has been studied with magnetic linear dichroism in angular dependence. The greatest intensities occurred for photon energies around the photoadsorption peak immediately before the main resonance. It is found no effect on the 4f satellite photoemission peaks as no dichroism is seen. A photoabsorption constant final state photoemission shows clear differences at the main resonance when it compares to magnetic circular dichroism results. This study also provides information of the maximum magnetic linear dichroism in angular dependence effect which can be seen for certain photon energies. The magnetic linear dichroism in angular distribution behaviour of the Gd 5p peaks through the giant resonance has also been studied

The effects of gamma noise on quality improvement

Taguchi's robust parameter design is an experimental procedure based on reducing the system variability that noise factors cause. The results, obtained under unrealistic assumptions about noise, may mislead practitioners when it comes to improving quality in robust design. For example, many hydrological data and the multi-path fading of a signal in wireless communication systems are positively skewed and cannot be modeled by any normal distribution. This manuscript focuses on the case where noise factor follows gamma distribution and investigates its true effects on the following: the response, the choice of an estimator in modeling, and the estimation of optimum factor settings. Then, a new density function is proposed for a given response under the gamma effect. A design of simulated experiments with gamma noise is conducted and two related examples are presented to illustrate the findings. © 2018, © 2018 Taylor & Francis Group, LLC

Buckling assessment of cylindrical steel tanks with top stiffening ring under wind loading

A stiffening ring is commonly used at the top of the tank wall to increase its strength against external pressure instability. Traditional design treatments generally consider cylindrical storage tanks under uniform external pressure for sizing of the top ring. However, cylindrical steel tanks under non-uniform wind loading have rather different and complex buckling behaviour from those of tanks subjected to uniform external wind loading. In this study, the buckling resistance of the cylindrical steel storage tanks with top stiffening ring under wind loading is investigated using finite element analyses. The changes in the buckling capacity are studied in light of the proposed stiffness ratio for a particular harmonic of wind loading. The results revealed that the changes in the buckling capacity are closely related to the shell-top ring stiffness ratio. Furthermore, a generalized solution that shows buckling pressure ratio (q(cr,w)/q(cr,D)) is then developed

Structural domain growth of strained gadolinium on Mo(112)

The growth mode of domains of the hexagonal lattice of strained gadolinium deposited on Mo(112) has been investigated with low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The molybdenum substrate corrugations and the expansive strain within the gadolinium films dominate the growth of the thin Gd films, which is characterized by a preferential domain growth direction of the hexagonal Gd crystal structure, unlike the more uniform, epitaxial growth of ‘unstrained’ gadolinium, grown on W(110)