bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compositional analysis of mixed–cation‐anion III–V semiconductor interfaces using phase retrieval high‐resolution transmission electron microscopy
Authors: MAHALINGAM K. , EYINK K.G. , BROWN G.J. , DORSEY D.L. , KISIELOWSKI C.F. , THUST A. 
Published: May 2008

SummaryEmploying exit‐plane wave function (EPWF) reconstruction in high‐resolution transmission electron microscopy (HRTEM), we have developed an approach to atomic scale compositional analysis of III‐V semiconductor interfaces, especially suitable for analyzing quaternary heterostructures with intermixing in both cation and anion sub‐lattices. Specifically, we use the focal‐series reconstruction technique, which retrieves the complex‐valued EPWF from a thru‐focus series of HRTEM images. A study of interfaces in Al0.4Ga0.6As–GaAs and In0.25Ga0.75Sb–InAs heterostructures using focal‐series reconstruction shows that change in chemical composition along individual atomic columns across an interface is discernible in the phase image of the reconstructed EPWF. To extract the interface composition profiles along the cation and anion sub‐lattices, quantitative analysis of the phase image is performed using factorial analysis of correspondence. This enabled independent quantification of changes in the In–Ga and As–Sb contents across ultra‐thin interfacial regions (approximately 0.6 nm wide) with true atomic resolution, in the In0.25Ga0.75Sb–InAs heterostructure. The validity of the method is demonstrated by analyzing simulated HRTEM images of an InAs–GaSb–InAs model structure with abrupt and graded interfaces. Our approach is general, permitting atomic‐level compositional analysis of heterostructures with two species per sub‐lattice, hitherto unfeasible with existing HRTEM methods.
Nanoparticle shape and configuration analysis by transmission electron tomography
Authors: AHRENKIEL S.P. , YU P.R. , MURPHY J.E. , NEDELJKOVIĆ J.M. , DONOHOE B.S. 
Published: May 2008

SummaryTomographic reconstruction by transmission electron microscopy is used to reveal three‐dimensional nanoparticle shapes and the stacking configurations of nanoparticle ensembles. Reconstructions are generated from bright‐field image tilt series, with a sample tilt range up to ± 70°, using single or dual tilt axes. We demonstrate the feasibility of this technique for the analysis of nanomaterials, using appropriate acquisition conditions. Tomography reveals both cubic and hexagonal close‐packing configurations in multi‐layered arrays of size‐selected In nanospheres. By tomography and phase‐contrast lattice imaging, we relate the three‐dimensional shape of PbSe octahedral nanoparticles to the underlying crystal structure. We also confirm simple‐cubic packing in multi‐layers of PbSe nanocubes and see evidence that the particle shapes have cubic symmetry. The shapes of TiO2 nanorod bundles are shown by tomographic reconstruction to resemble flattened ellipsoids.
Immuno‐EM using colloidal metal nanoparticles and electron spectroscopic imaging for co‐localization at high spatial resolution
Authors: BLEHER R. , KANDELA I. , MEYER D.A. , ALBRECHT R.M. 
Published: May 2008

SummaryMultiple‐labelling immuno‐EM is a powerful tool for localizing and co‐localizing different antigens simultaneously in cells and tissues at high spatial resolution. Commonly used labels for this purpose are differently sized gold spheres. A comparison of results obtained with differently sized markers is often difficult, because the diameters of markers influence labelling efficiency. In the current study, we investigate a method for high‐resolution multiple‐labelling immuno‐EM, using equally sized colloidal markers made of different metals. Energy filtering transmission electron microscopy is used to differentiate particles based on elemental composition. The labels consist of colloidal gold, palladium and platinum‐core gold‐shell particles of approximately 6 nm in diameter, which are conjugated to different primary antibodies. Applicability of the electron spectroscopic imaging, methodology is demonstrated by labelling of actin, α‐actinin and myosin on ultra‐thin cryosections of skeletal muscle tissue.
Modelling a ceramic foam using locally adaptable morphology
Authors: LAUTENSACK C. , GIERTZSCH M. , GODEHARDT M. , SCHLADITZ K. 
Published: May 2008

SummaryIn this paper, a ceramic open foam is modelled using a two‐step procedure. First, a random Laguerre tessellation is fitted to the edge system of the polyurethane foam forming the core of the ceramic foam. In a second phase, a model of the ceramic foam is obtained using dilations with balls of locally varying size. The model fitting is based on geometric characteristics of both polyurethane and ceramic foam estimated from reconstructed tomographic images of these structures.
Application of EBSD to the analysis of interface planes: evolution over the last two decades
Authors: RANDLE V. 
Published: May 2008

SummaryOver the last two decades, several methods, of increasing sophistication, have evolved to measure boundary plane orientation by electron backscatter diffraction. Originally, metallographic sectioning was used to obtain the location of the boundary plane. The most recently designed approach allows the relative frequency distribution of boundary misorientation and boundary plane types to be obtained, for very large sample populations, by a stereological method. In this review, the progress in measuring boundary planes by electron backscatter diffraction is charted. Each technique is described in chronological order, illustrated by a series of examples, all relating to boundary plane reorientation.
Texture evolution in grain‐oriented electrical steel during hot band annealing and cold rolling
Authors: SHIN S. M. , BIROSCA S. , CHANG S. K. , DE COOMAN B. C. 
Published: May 2008

SummaryThe optimization of magnetic and physical properties of electrical steel is imperative for many engineering applications. The key factors to improve magnetic properties are the steel composition as well as control of the crystallographic orientation and microstructure of the steel during processing. However, this requires careful control of processing at all stages of production. Under certain conditions of deformation and annealing, electrical steel can be produced to have favourable texture components. For grain‐oriented (GO) electrical steels that are used in most transformer cores, a pronounced {110}〈001〉 Goss texture plays a vital role to achieve low power losses and high permeability. Essentially, Goss texture develops during secondary re‐crystallization in GO electrical steels; however, the mechanism of the abnormal Goss grain growth is still disputed in the literature. In the current study, the influence of the annealing conditions on the development of annealing, cold rolling and re‐crystallization textures of hot‐rolled GO electrical steel were investigated in detail following each processing step. Furthermore, the orientation data from electron backscatter diffraction were used to evaluate the orientation‐dependent stored energy of deformed grains after hot rolling. In the light of new findings in the present study, annealing and deformation texture development mechanisms were critically reviewed.
Oxide formation and alloying elements enrichment on TRIP steel surface during inter‐critical annealing
Authors: GONG Y. F. , BIROSCA S. , KIM H. S. , DE COOMAN B. C. 
Published: May 2008

SummaryThe gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub‐surface of sheet steels. The alloying element enrichments and the oxide morphology on transformation‐induced plasticity steel surfaces are strongly influenced by the dew point of the furnace atmosphere and annealing temperature. The formation of a thin oxide film and enrichment of the alloying elements during annealing may result in surface defects on galvanized sheet products. The present contribution reports on the use of microanalysis techniques such as electron backscatter diffraction, glow discharge optical emission spectroscopy and electron probe micro‐analysis for the detailed surface analysis of inter‐critically annealed transformation‐induced plasticity steel such as oxide phase determination, microstructure and microtexture evolutions.
Using EBSD and TEM‐Kikuchi patterns to study local crystallography at the domain boundaries of lead zirconate titanate
Authors: FAROOQ M. U. , VILLAURRUTIA R. , MACLAREN I. , KUNGL H. , HOFFMANN M. J. , FUNDENBERGER J.‐J. , BOUZY E. 
Published: May 2008

SummaryReliable EBSD mapping of 90° domains in a tetragonal ferroelectric perovskite has been achieved for the first time, together with reliable automated orientation determination from TEM‐Kikuchi patterns. This has been used to determine misorientation angles at 90° domain boundaries and thus local c/a ratios. The sources of orientation noise/error and their effects on the misorientation angle data have been thoroughly analyzed and it is found that this gives a cosine distribution of misorientation angles about the mean with a characteristic width related to the width of the orientation noise distribution. In most cases, a good agreement is found between local c/a ratios and global measurements by X‐ray diffraction, but some clear discrepancies have also been found suggesting that real local variations are present, perhaps as a consequence of compositional inhomogeneities.
On the orientations of abnormally grown grains in nanocrystalline Ni and Ni–Fe
Authors: KLEMENT U. , Da SILVA M. , SKROTZKI W. 
Published: May 2008

SummaryThe scanning electron microscopy–based electron backscatter diffraction technique has been used to determine grain orientations of abnormally grown grains upon annealing in nanocrystalline Ni and Ni–20 at.% Fe electrodeposits. The results show that in nanocrystalline Ni and Ni–Fe, the first grown grains that can be detected are 〈411〉 oriented with respect to the normal direction (〈411〉//ND). Upon annealing, further grain growth occurs and the dominant orientation of the abnormally growing grains changes from 〈411〉//ND to 〈111〉//ND. Twinning is found to be the mechanism responsible for the orientation change and is for the first time described in connection with abnormal grain growth in nanocrystalline materials. This means that well‐known models for the formation of annealing twins (initially introduced in connection with recrystallization) also seem to apply in nanocrystalline materials.
Recrystallization phenomena in an IF steel observed by in situ EBSD experiments
Authors: NAKAMICHI H. , HUMPHREYS F. J. , BROUGH I. 
Published: May 2008

Summary In situ electron backscatter diffraction microstructural analysis of recrystallizing interstitial free steels deformed to strains of 0.75 and 1.6 has been carried out in a FEG‐SEM. The experimental procedures are discussed, and it is shown that there is no degradation of the electron backscatter diffraction patterns at temperatures up to 800°C. Analysis of the surface and interior microstructures of annealed samples shows only minor difference, which suggests that in situ annealing experiments are of value. In addition, it is shown that in situ measurements allow a detailed comparison between the same areas before and after annealing, thereby providing information about the recrystallization mechanisms. Sequential recrystallization phenomena, such as initiation and growth of new grains, are observed at temperatures over 740°C, and depending on the deformation histories, different recrystallization behaviour is observed. It is found that {111}〈123〉 recrystallized grains are preferentially formed in the highly deformed material, whereas no strong recrystallization texture is formed in the lower strained material.
Three‐dimensional EBSD study on the relationship between triple junctions and columnar grains in electrodeposited Co–Ni films
Authors: BASTOS A. , ZAEFFERER S. , RAABE D. 
Published: May 2008

SummaryElectrodeposited nanocrystalline materials are expected to have a homogeneous grain size and a narrow grain size distribution. In Co–Ni electrodeposited films, however, under certain conditions an undesired columnar grain structure is formed. Fully automated three‐dimensional (3D) orientation microscopy, consisting of a combination of precise material removal by focussed ion beam and subsequent electron backscatter diffraction (EBSD) analysis, was applied to fully characterize the grain boundaries of these columnar grains in order to gain further understanding on their formation mechanisms. Two‐dimensional orientation microscopy on these films indicated that the development of columnar grains could be related to the formation of low‐energy triple junctions. 3D EBSD allowed us to verify this suggestion and to determine the boundary planes of these triples. The triplets are formed by grain boundaries of different quality, a coherent twin on the {} plane, an incoherent twin and a large‐angle grain boundary. These three boundaries are related to each other by a rotation about the 〈〉 direction. A second particularity of the columnar grains is the occurrence of characteristic orientation gradients created by regular defects in the grain. Transmission electron microscopy was applied to investigate the character of the defects. For this purpose, a sample was prepared with the focussed ion beam from the last slice of the 3D EBSD investigation. From the TEM and 3D EBSD observations, a growth mechanism of the columnar grains is proposed.
EBSD as a tool to identify and quantify bainite and ferrite in low‐alloyed Al‐TRIP steels
Authors: ZAEFFERER S. , ROMANO P. , FRIEDEL F. 
Published: May 2008

SummaryBainite is thought to play an important role for the chemical and mechanical stabilization of metastable austenite in low‐alloyed TRIP steels. Therefore, in order to understand and improve the material properties, it is important to locate and quantify the bainitic phase. To this aim, electron backscatter diffraction–based orientation microscopy has been employed. The main difficulty herewith is to distinguish bainitic ferrite from ferrite because both have bcc crystal structure. The most important difference between them is the occurrence of transformation induced geometrically necessary dislocations in the bainitic phase. To determine the areas with larger geometrically necessary dislocation density, the following orientation microscopy maps were explored: pattern quality maps, grain reference orientation deviation maps and kernel average misorientation maps. We show that only the latter allow a reliable separation of the bainitic and ferritic phase. The kernel average misorientation threshold value that separates both constituents is determined by an algorithm that searches for the smoothness of the boundaries between them.
Spherical EBSD
Authors: DAY A.P. 
Published: May 2008

SummarySpheres, or more usually spherical surfaces, are important in electron backscatter diffraction. Both electron backscatter patterns (EBSPs) and pole figure texture data are more accurately represented on the spherical surface, S2; and unit quaternions, which are the optimal method for orientation calculations, exist on the surface of the hypersphere, S3.This paper is split into two distinct parts. The first shows a little of the history of the EBSP technique, including the use of spheres to assemble a spherical Kikuchi map (SKM) and as calibration artefacts. The second part relates new developments in the analysis of EBSPs on the surface of a sphere, a new spherical Hough transform and ideas for fully automatic,ab initioanalysis of unknown phases using collections of EBSPs assembled as spherical Kikuchi maps.
A 3D Hough transform for indexing EBSD and Kossel patterns
Authors: MAURICE C. , FORTUNIER R. 
Published: May 2008

SummaryA three‐dimensional Hough transform is designed for the detection of conic curves (hyperbolae and ellipses) formed by the gnomonic projection of diffraction Kossel cones. This new procedure is applied to a high‐angular‐accuracy analysis of electron backscatter diffraction (EBSD) patterns and to a fully automatic indexing of X‐ray Kossel patterns in the SEM. The high‐accuracy analysis of EBSD patterns allows for the determination of local elastic strains, without any reference pattern, and with a spatial resolution of a few tens of nanometres. An accuracy of 2 × 10−4 is achieved on geometrically calculated diagrams. This paper presents also the first fully automatic indexing of Kossel patterns. This automatic indexing procedure can be applied to local texture analysis, as well as to local elastic strain measurements. Although the spatial resolution of Kossel is about 1 μm, the accuracy of strain measurement is in this case much higher than that presently obtained on EBSD.
Infectious complications in living‐donor liver transplant recipients: a 9‐year single‐center experience
Authors: Kim Y.J. , Kim S.I. , Wie S.H. , Kim Y.R. , Hur J.A. , Choi J.Y. , Yoon S.K. , Moon I.S. , Kim D.G. , Lee M.D. , Kang M.W. 
Published: May 2008

Background. Infectious complications following living‐donor liver transplantation (LDLT) remain a major cause of morbidity and mortality. We analyzed the frequency and type of infectious complications according to the post‐transplantation period, and their risk factors with regard to morbidity and mortality.Methods. We retrospectively analyzed 208 subjects who had undergone LDLT during a 9‐year period.Results. The rate of infection was 1.69 per patient during the study period. The predominant infections were intra‐abdominal infections (37.6%), primary bacteremia (17.4%), and pneumonia (14.5%). Within the first post‐transplant month, 140 (39.9%) infections were detected, and catheter‐related coagulase‐negative staphylococci (44) were the most common infectious agents. During the 2–6‐month post‐transplant period, 109 infectious episodes occurred (31.1%), and Enterococcus sp. (n=16) related to biliary infection was the most frequent isolate. After the sixth month, 96 infectious episodes (29%) occurred, and biliary tract‐related Escherichia coli (n=19) was the major causative organism. The overall mortality was 24.5% (51/208); 1‐year survival rate was 88% (196/208). Post‐transplant infection‐related mortality was 52.9% (27/51). Biliary tract complications, such as biliary stenosis or leakage, significantly increased the mortality (P=0.01); however, reoperation (retransplantation or resurgery for biliary tract obstruction/leakage or to control bleeding) significantly reduced the mortality (P=0.01).Conclusions. Our data showed that early catheter removal would mainly aid in reducing infectious complications in the 1‐month post‐transplantation period. Aggressive management, including reoperation, would lower the mortality in the LDLT recipients.
SEVOFLURANE POST‐CONDITIONING PROTECTS AGAINST MYOCARDIAL REPERFUSION INJURY BY ACTIVATION OF PHOSPHATIDYLINOSITOL‐3‐KINASE SIGNAL TRANSDUCTION
Authors: Li Heng , Wang Jun‐Ke , Zeng Yin‐Ming , Yang Cheng‐Xiang , Chen Hong‐Tao , Wen Xian‐Jie , Shui Chun‐Ling , Liang Hua 
Published: May 2008

SUMMARY

The mechanisms underlying myocardial protection by sevoflurane post‐conditioning are unclear. In the present study, we tested two hypotheses: (i) that sevoflurane post‐conditioning produces cardioprotection via a phosphatidylinositol‐3‐kinase (PI3‐K)‐dependent pathway; and (ii) combining sevoflurane and ischaemic post‐conditioning offers an additional benefit against reperfusion injury.
Rat isolated perfused hearts were exposed to 25 min ischaemia followed by 90 min reperfusion. Sevoflurane post‐conditioning was induced by administration of sevoflurane (3.0 vol%) for 15 min from the onset of reperfusion. In some groups, 15 µmol/L LY294002, a selective PI3‐K inhibitor, was coadministrated with sevoflurane. Other groups of hearts were exposed to ischaemic post‐conditioning or combined sevoflurane plus ischaemic post‐conditioning in the presence and absence of LY294002. After 15 min reperfusion, phosphorylation of Akt and glycogen synthase kinase 3β (GSK3β) was determined by Western blot analysis. Infarct size was determined by 2,3,5‐triphenyltetrazolium chloride staining and subsarcolemmal mitochondrial lesions were assessed by electron microscopy after 90 min reperfusion.
Sevoflurane post‐conditioning significantly decreased infarct size compared with control hearts (31 ± 2 vs 42 ± 3%, respectively; P < 0.05), diminished mitochondrial lesions and increased phosphorylation of Akt and GSK3β, as did ischaemic post‐conditioning. However, combined sevoflurane plus ischaemic post‐conditioning did not further improve the cardiaoprotective effects compared with either intervention alone. Sevoflurane‐mediated cardioprotection was abolished or inhibited by 15 µmol/L LY294002.
In conclusion, sevoflurane acts during early reperfusion after ischaemia to salvage the myocardium by activating PI3‐K. The combination of sevoflurane plus ischaemic post‐conditioning does not offer any additional benefit over either intervention alone.
ILLUMINATING THE STRUCTURE AND FUNCTION OF CYS‐LOOP RECEPTORS
Authors: Pless Stephan A , Lynch Joseph W 
Published: May 2008

SUMMARY

Cys‐loop receptors are an important class of ligand‐gated ion channels. They mediate fast synaptic neurotransmission, are implicated in various ‘channelopathies’ and are important pharmacological targets. Recent progress in X‐ray crystallography and electron microscopy has provided a considerable insight into the structure of Cys‐loop receptors. However, data from these experiments only provide ‘snapshots’ of the proteins under investigation. They cannot provide information about the various conformations the protein adopts during transition from the closed to the open and desensitized states.
Voltage‐clamp fluorometry helps overcome this problem by simultaneously monitoring movements at the channel gate (through changes in current) and conformational rearrangements in a domain of interest (through changes in fluorescence) in real time. Thus, the technique can provide information on both transitional and steady state conformations and serves as a real time correlate of the channel structure and its function.
Voltage‐clamp fluorometry experiments on Cys‐loop receptors have yielded a large body of data concerning the mechanisms by which agonists, antagonists and modulators act on these receptors. They have shed new light on the conformational mobility of both the ligand‐binding and the transmembrane domain of Cys‐loop receptors.