FMR Study of Co/Ti Bilayer Thin Films

. We focused on the interaction between two ferromagnetic cobalt layers through a non-magnetic titanium layer. The magnetic properties of the structure were characterized by ferromagnetic resonance technique (FMR). The data were collected as a function of non-magnetic titanium layer thickness. Co/Ti multilayer (Ti (50 {\AA})/Co(45 {\AA})/Ti(2-40 {\AA})/Co(40 {\AA})/Ti(100 {\AA}))films were grown onto naturally oxidized p-type single crystal Si (100) substrate at UHV condition with magnetron sputtering system at room temperature. The thickness of Ti spacer layer ranges from 2 to 40 {\AA} with 2 {\AA} steps. We did not observe usual optic and acoustic modes; instead we had two broad overlapped peaks for the films ranged from 6 {\AA} to 40 {\AA}. One interesting result was the high anisotropic resonance field values for these films. Exchange coupling between ferromagnetic layers causes shift on resonance field values but these shifts in our samples were much larger than expected. This large anisotropic behavior is not clear at the moment. Our theoretical model was not able to determine a value for the exchange coupling parameter. One reason can be the close thickness values for Co sublayers. The other reason can be the Ti non-magnetic layer. If titanium did not grow layer by layer on cobalt, the cobalt ferromagnetic layers may behave as a single layer. As a result one cannot observe exchange interaction between ferromagnetic layers through non-magnetic spacer.Comment: 6 pages, 5 figure

Discrete Cutting Force Model for 5-Axis Milling with Arbitrary Engagement and Feed Direction

5-axis machining operations bring new challenges for predicting cutting forces. Complex tool workpiece engagements and tool orientations make it difficult to adapt 3-axis process models for 5-axis operations. A new model is developed to predict cutting forces with arbitrary tool/workpiece engagement and tool feed direction. A discretization approach is used, in which the tool is composed of multiple cutting elements. Each element is processed to determine its effect on cutting forces, and global forces are determined by combining the elemental effects. Cutting tests are conducted to verify force predictions, where the tool/workpiece engagement is provided through a geometric software application

Homozygosity at variant MLH1 can lead to secondary mutation in NF1, neurofibromatosis type I and early onset leukemia

Cataloged from PDF version of article.Heterozygous germ-line variants of DNA mismatch repair (MMR) genes predispose individuals to hereditary non-polyposis colorectal cancer. Several independent reports have shown that individuals constitutionally homozygous for MMR allelic variants develop early onset hematological malignancies often associated to features of neurofibromatosis type 1 (NF1) syndrome. The genetic mechanism of NF1 associated to MMR gene deficiency is not fully known. We report here that a child with this form of NF1 displays a heterozygous NF1 gene mutation (c.3721C > T), in addition to a homozygous MLH1 gene mutation (c.676C > T) leading to a truncated MLH1 protein (p.R226X). The parents did not display NF1 features nor the NF1 mutation. This new NF1 gene mutation is recurrent and predicts a truncated neurofibromin (p.R1241X) lacking its GTPase activating function, as well as all C-terminally located functional domains. Our findings suggest that NF1 disease observed in individuals homozygous for deleterious MMR variants may be due to a concomitant NF1 gene mutation. The presence of both homozygous MLH1 and heterozygous NF1 mutation in the child studied here also provides a mechanistic explanation for early onset malignancies that are observed in affected individuals. It also provides a model for cooperation between genetic alterations in human carcinogenesis. © 2007 Elsevier B.V. All rights reserved

The central dogma of biological homochirality: How does chiral information propagate in a prebiotic network?

Biological systems are homochiral, raising the question of how a racemic mixture of prebiotically synthesized biomolecules could attain a homochiral state at the network level. Based on our recent results, we aim to address a related question of how chiral information might have flowed in a prebiotic network. Utilizing the crystallization properties of the central RNA precursor known as ribose-aminooxazoline (RAO), we showed that its homochiral crystals can be obtained from its fully racemic solution on a magnetic mineral surface, due to the chiral-induced spin selectivity (CISS) effect. Moreover, we uncovered a mechanism facilitated by the CISS effect through which chiral molecules, like RAO, can uniformly magnetize such surfaces in a variety of planetary environments in a persistent manner. All this is very tantalizing, because recent experiments with tRNA analogs demonstrate high stereoselectivity in the attachment of L-amino acids to D-ribonucleotides, enabling the transfer of homochirality from RNA to peptides. Therefore the biological homochirality problem may be reduced to ensuring that a single common RNA precursor (e.g. RAO) can be made homochiral. The emergence of homochirality at RAO then allows for the chiral information to propagate through RNA, then to peptides, and ultimately, through enantioselective catalysis, to metabolites. This directionality of the chiral information flow parallels that of the central dogma of molecular biology--the unidirectional transfer of genetic information from nucleic acids to proteins.Comment: 8 pages, 4 figure

Application-Specific Heterogeneous Network-on-Chip Design

Cataloged from PDF version of article.As a result of increasing communication demands, application-specific and scalable Network-on-Chips (NoCs) have emerged to connect processing cores and subsystems in Multiprocessor System-on-Chips. A challenge in application-specific NoC design is to find the right balance among different tradeoffs, such as communication latency, power consumption and chip area. We propose a novel approach that generates latency-aware heterogeneous NoC topology. Experimental results show that our approach improves the total communication latency up to 27% with modest power consumption. © 2013 The Author 2013. Published by Oxford University Press on behalf of The British Computer Society

Photoelectron Diffraction Determination of the Structure of Ultrathin Vanadium Films on Cu(001)

X-ray photoelectron diffraction (XPD) and low-energy electron diffraction (LEED) have been used to study the structural properties of V thin films on Cu(001). For room-temperature growth, submonolayer coverages result in (1x1) LEED patterns that evolve to exhibit very diffuse (2x1) structure at approximately 1 monolayer coverage. We do not observe any V forward-focusing enhancements for V films that exhibit either the (1x1) or (2x1) structure, suggesting that these structures are limited to the first 1-2 vanadium layers. At coverages above 1 monolayer, the V films display complex LEED patterns characteristic of four bcc(110) domains. This structure persists to V coverages as high as 100 ML, and the LEED and XPD angular scans suggest that V in these films retain the bulk V lattice constant. These results have important ramifications for predictions of magnetic order in vanadium thin films that typically assume pseudomorphic growth

Work holding assessment of an UV adhesive and fixture design method

Adhesive work holding can be used to minimize clamping distortion and provide greater access to a work piece during machining. This paper proposes shear and tensile strength criteria to evaluate the work holding strength of adhesive grippers and definition of a strength safety coefficient of adhesive grippers. It also demonstrates a case study of work holding design with an UV adhesive for a grinding process based on a strength criteria explained in the paper. A test rig has been designed and manufactured to assess the capability of an adhesive work holding material. Tests include measurement of strength and repeatability of adhesion under different film thicknesses, curing times and pre-cleaning methods. The test shows the strength repeatability is less than ± 20%, which is good enough for many work holding applications. A shear-tensile combined strength can be evaluated by the strength sphere in a fixture design of a specific part geometry for production by the combined safety coefficient. Following the test rig assessment, a fixture has been designed with 3 grippers to demonstrate the adhesive for a grinding process with a simple part geometry. The method has a high potential for application in industry, and is not limited to the given part geometry and machining method. The grinding test shows that the adhesive work holding is strong enough for the application and that similar results can be expected for milling and turning with a good gripper arrangement

Heterogeneous network-on-chip design through evolutionary computing

This article explores the use of biologically inspired evolutionary computational techniques for designing and optimising heterogeneous network-on-chip (NoC) architectures, where the nodes of the NoC-based chip multiprocessor exhibit different properties such as performance, energy, temperature, area and communication bandwidth. Focusing primarily on array-dominated applications and heterogeneous execution environments, the proposed approach tries to optimise the distribution of the nodes for a given NoC area under the constraints present in the environment. This article is the first one, to our knowledge, that explores the possibility of employing evolutionary computational techniques for optimally placing the heterogeneous nodes in an NoC. We also compare our approach with an optimal integer linear programming (ILP) approach using a commercial ILP tool. The results collected so far are very encouraging and indicate that the proposed approach generates close results to the ILP-based approach with minimal execution latencies. © 2010 Taylor & Francis

Metalorganic chemical vapor deposition growth and thermal stability of the AllNN/GaN high electron mobility transistor structure

Cataloged from PDF version of article.The AlxIn1-xN barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al0.83In0.17 N barrier exhibits a sheet electron density of 2.0 x 10(13) cm(-2) with a high electron mobility of 1540 cm(2) V-1 s(-1). AnAl(0.83)In(0.17)N barrier HEMT device with 1 mu m gate length provides a current density of 1.0 A mm(-1) at V-GS = 0 V and an extrinsic transconductance of 242 mS mm(-1), which are remarkably improved compared to that of a conventional Al0.3Ga0.7N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 degrees C have been applied to Al0.83In0.17N and Al0.3Ga0.7N barrier heterostructures. As expected, the electrical properties of an Al0.83In0.17N barrier HEMT structure showed less stability than that of an Al0.3Ga0.7N barrier HEMT to the thermal annealing. The structural properties of Al0.83In0.17N/GaN also showed more evidence for decomposition than that of the Al0.3Ga0.7N/GaN structure after 800 degrees C post-annealing

A case of pulmonary aspergillosis in white storks

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗAspergillosis is a fungal infection affecting respiratory system both in mammals and avian species. It is more commonly encountered in birds, in comparison with its mammalian counterpart. Mostly isolated strains are Aspergillus fumigatus (95%) and Aspergillus flavus (5%). Affected lungs and air sacs reveal miliary to gross lesions like gray-yellowish or white-grayish granulomatous foci surrounded by white halos indicative of inflammatory infiltration. Five storks found dead in the rural areas near Istanbul were submitted to our faculty between years 2008 and 2014. Two of them were thought to be younger than 1-year-old and the other three were older than one year of age. Necropsies were performed right after their submissions. Aspergillosis lesions were observed in the lungs and thoracic air sacs of the first four storks. In addition to these changes the lesions were detected at the aortic bifurcation and on the testicular and renal capsule of the fifth stork. Histopathology revealed encapsulated granulomas with foci of caseous necrosis at the center surrounded by numerous macrophages, heterophil leukocytes, lymphocytes and foreign body giant cells in all the storks. Following the gross, histopathological and mycological examinations the agents were detected as Aspergillus fumigatus. Although, the number of reported deaths due to Aspergillosis is not high in storks, we believe that these birds are quite susceptible to the disease and stress factors such as migration increases the risk of pathogenicity. This report was designed as a contribution to literature since there is only one reported case available with respect to aspergillosis associated death in storks and stress factors such as migration may also predispose storks to the disease