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The oxide/semiconductor interface state density (Dit) in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) structures with gate oxides grown by atomic layer deposition at low deposition temperature is analyzed in this work. MOS-HEMT structures with Al2O3 gate oxide were deposited at 100 and 300 °C using trimethylaluminum precursor and H2O and O3 oxidation agents. The structures were found to show negative net charge at oxide/barrier interface with density (Nint) of 1013 cm−2, which was attributed to the reduction of barrier surface donor density (NDS). Dit was determined using capacitance transient techniques, and the results were assessed by the simulations of the capacitance–voltage characteristics affected by interface traps. The results indicate a lower interface quality of the sample with Al2O3 grown using O3 agent compared to those with H2O, even though the former provided lowest gate leakage among the analyzed structures. Moreover, to uncover the NDS nature, Dit...

Blue light-emitting quantum wires are fabricated by molecular beam epitaxy of ZnCdSe/ZnSe on patterned GaAs substrates. In these structures, lateral carrier confinement is obtained by the anisotropic growth of ZnSe. Two luminescence bands are observed, due to emission from the ridge quantum wire and due to luminescence of the QW grown on the bottom of the grooves between the ridges. The exciton decay is studied by time-resolved photoluminescence experiments. At the emission band of the quantum wire, a local lifetime maximum is observed as well as a biexponential exciton decay. Both are attributed to a lifetime elongation caused by the lateral quantum confinement of the excitons within the ridge wires.

It is shown in this paper that – in contrast to the accepted belief in the literature – it is possible to determine if a minority component is located on the dodecahedral, octahedral or tetrahedral sites in a garnet single crystal. Previous literature regarded the dodecahedral sites indistinguishable form the tetrahedral sites. Our prediction about the separability is based upon dynamical Bloch-wave calculations and proved experimentally in a transmission electron microscope (TEM) on two different natural garnets (almandine and grossular). The crystallographic positions of the minority components are determined in an ALCHEMI experiment that makes use of the channeling of electrons in special directions of a single-crystal sample.

The damage generation of a 3.5 MeV 4 He + analyzing beam in 4H-SiC during Rutherford backscattering spectrometric (RBS) measurement was studied by channeling effect measurements (RBS/C). A dose rate dependence of the minimum yield ( χ min ) was found, i.e., higher damage accumulation occurs with higher dose rate. On the other hand, the dose dependence shows that in the applied dose range (⩽3 × 10 17 ions/cm 2 ) there is an effective dose region where χ min increases with dose, whereas it almost remains unchanged outside of this range. The behavior of analyzing beam induced damage was also discussed according to RBS observations.

Morphology, electron structure, and catalytic activity in CO oxidation over a Au/FeOx/SiO2/Si(100) model sample prepared by pulsed laser deposition (PLD) have been investigated by X-ray photoelectron spectroscopy (XPS), UV photoelectron spectroscopy (UPS), and transmission electron microscopy (TEM). Two types of sample were prepared denoted by PLD I and PLD II, the latter being prepared by multiple laser deposition alternatively by iron and gold. PLD I was characterized in “as prepared” oxidized and reduced states, the respective gold particle sizes being 3.8, 4.1, and 5 nm; the iron oxide support was amorphous after the first two treatments while it was partially crystallized after reduction. The activity in CO oxidation increased after oxidation of the sample, whereas it was diminished after subsequent reduction. XPS studies showed that higher activity was associated with amorphous iron oxide with Fe 2p binding energy = 711.3 eV. It was established that in developing the catalytic activity the gold shou...

1 wt% Au/Fe2O3 catalyst was prepared by a co‐precipitation method. The structure of the sample in the as prepared, oxidized and reduced states was investigated by means of X‐ray photoelectron spectroscopy (XPS), transition electron microscopy (TEM), electron diffraction (ED) and X‐ray diffraction (XRD). The structure of the samples after various treatments and their activity in the CO oxidation were compared. The results show the stability of the gold particle size during the treatments. However, after oxidation, a slight shift in the Au 4f binding energy towards lower values points to the formation of an electron‐rich state of the metallic gold particles compared to that revealed in the as prepared sample. Simultaneously, a goethite phase in the Fe2O3 support is present, which is not observed in the “as prepared” and reduced samples. In the reduced sample the presence of a crystalline maghemite‐c phase indicates a change in the support morphology. In the CO oxidation the oxidized sample shows the highest activity and it might be the result of the cooperative effect of goethite, FeO and the electron‐rich metallic gold nanoparticles. We suggest that a structural transformation occurs along the gold/support perimeter during the treatments and we propose a possible mechanism for the effect of the oxidation treatment.

Al doped zinc oxide (AZO) layers were deposited onto soda lime glass substrate by reactive magnetron sputtering. Properties of the reactive plasma were monitored. Our results show two characteristic behaviors (hysteresis and oscillation). A qualitative physical explanation for spontaneous and stable plasma oscillations is provided. Necessary conditions for the formation of the oscillation phenomena are studied as a function of oxygen mass flow and power.

The growth process of GaN layers grown by metalorganic chemical vapor deposition on sapphire is characterized by transmission electron microscopy and atomic force microscopy. The nitridation of the sapphire substrate and GaN buffer layers as well as film structure and the nature of defects are studied. Nitridation causes the formation of a 4 nm thick AlN layer on sapphire. GaN buffer layers grown at 510 °C are found to be hexagonal single crystals in their as-grown state with a mosaic structure. Annealing of the buffer layers leads to substantial smoothening of their surfaces due to the coalescence of the grains. GaN layers themselves are single crystalline, hexagonal, and epitaxial to the substrate. Layers grown on exactly oriented (0001) type substrate as well as on miscut substrate are compared. Smooth surfaces have been achieved on exactly oriented and on miscut substrates as well, but the range of the deposition parameters is wider when miscut substrates are used.

Resume Tout comme les autres maladies auto-immunes systemiques, la polyarthrite rhumatoide peut impliquer plusieurs autres organes avec des manifestations immunologiques complexes. Le purpura thrombocytopenique auto-immun cause par une reaction auto-immune contre les plaquettes est une complication hematologique rare. Chez une patiente atteinte de polyarthrite rhumatoide, un purpura thrombocytopenique auto-immun est apparu rapidement a la suite de l’abandon de la corticotherapie orale. L’atteinte de la muqueuse du caecum, du colon ascendant et de l’antre du pylore etait compliquee par le saignement d’un polype gastrique au nadir de la crise de thrombopenie. L’hemorragie a ete prise en charge par une intervention endoscopique et en deux jours la numeration plaquettaire s’est amelioree avec une corticotherapie a forte dose.

Rheumatoid arthritis, in common with other systemic autoimmune diseases, can involve several other organs presenting with complex immunological manifestations. Immune thrombocytopenic purpura caused by an autoimmune reaction against platelets is an infrequent haematological complications. A female patient with rheumatoid arthritis rapidly developed extremely severe immune thrombocytopenic purpura upon suspending oral corticosteroid therapy. Besides the involvement of the mucosa of the coecum, ascending colon and the gastric antrum, the situation was further complicated by bleeding of a gastric polyp, at the nadir of the thrombocytopenic crisis. The bleeding was managed by endoscopic intervention and platelet count recovered upon high dose corticosteroid treatment within a couple of days.

We prepared a series of nominally undoped microcrystalline silicon (μc-Si:H) films in a conventional radio frequency plasma enhanced chemical vapor deposition reactor from silane diluted with hydrogen. To investigate the transport mechanism we carried out measurements of the dark conductivity, σd, Hall mobility, μH, and thermoelectric power, S, in the temperature range 200 to 450 K. The activated temperature dependences of μH and of a quantity, Q, derived from σd and S indicate that the transport properties are determined by an inhomogeneous distribution of the charge carriers (electrons). We analyze our results in terms of two models. The first one assumes potential barriers, not at the grain boundaries but at the interfaces of the columns which are typical for μc-Si:H. In the second model inhomogeneously distributed charged centers give rise to potential fluctuations. Both models can equally well account for our experimental data.

The magnetic coupling between nanosize ferromagnetic bcc crystalline grains embedded in a residual amorphous matrix was studied by Mossbauer spectroscopy in nanocrystalline Fe - Zr - B - Cu alloys studied above the Curie temperature of the amorphous phase. It is shown that the ferromagnetic coupling is mediated via an about two atomic layer thick interface region between the nanocrystallites.

Zn 1-x Cd x Se/ZnSe quantum wells were grown by molecular beam epitaxy on GaAs substrates with a sub-micron grating along the [1 1 0]-direction. The synthesized structures were examined by means of transmission electron and scanning electron microscopy. proving that selective growth takes place. The reduced growth rate on the sidewalls of the grooves leads to a narrowing of the upper plateaux of the top ridges confining the two-dimensional layers laterally. From photoluminescence measurements of coherently grown samples, we can determine a blue shift with respect to the unpatterned reference samples. The blue shift of the grooves depends strongly on the total thickness of the ZnSe films, indicating complex strain effects in the layers.

GaN layers grown by MOCVD have been characterised by TEM. The layers are single crystalline, hexagonal and epitaxial to the substrate. Layers grown onto exactly oriented (0001) type substrate as well as onto miscut substrate are compared. In this study the defect structure of the layers is discussed placing emphasis on the frequently observed hexagonal rods surrounded by inversion domain boundaries. (orig.) 14 refs.

The Mossbauer spectra of nanocrystallized amorphous Fe-Zr based alloys are compared to those of melt-quenched microcrystalline Fe-Zr solid solution in the 4-800 K temperature and in the 0-7 T external magnetic field range. It is established for both cases that besides the well known sharp sextet of the bcc Fe phase (main line) and the broad spectrum component a satellite is also observed. Its hyperfine field shows the same temperature and external magnetic field dependence as that of the bcc structure. The results together with high precision X-ray data for the grain size and lattice parameter as a function of the nanocrystallization temperature make it possible to identify that the satellite is caused by (mainly) Zr dissolved in the bcc structure. Our results do not support the idea that the satellite structure is due to a separate interfacial phase.

The atomic and microstructure of Ni-richB2 NixAl100 − x thin fllms with nanoscale dimensions, for thickness as well as lateral grain size, and produced by evaporation onto NaCl and KCl (001) surfaces are investigated by high resolution electron microscopy. Different textures and orientation relationships with the substrate are found exhibiting grains with [001], [011] and [111] zones parallel with the film normal. Local distortions including precursor-like domains and surface shearing as well as dislocations are observed in the grains. No micromodulations as in bulk martensite precursors are visible. No martensitic transformation was observed when cooling the free standingfilms to −170 °C.

In this study an investigation is presented on LPCVD deposited and annealed Si-rich SiN x layers on Si substrates. The samples prepared by this way were characterized by capacitance–voltage, current–voltage, and memory hysteresis measurements. The electrical properties were studied as a function of annealing temperature. Systematic dependence of the flat-band voltage and the current have been obtained on the annealing conditions.

GaN layers grown onto sapphire substrates by metalorganic chemical vapour deposition were characterised by optical microscopy, transmission electron microscopy and atomic force microscopy measurements. Mirror like surfaces were obtained at certain growth conditions despite the hexagonal based pyramids found on the growth surface. The typical pyramids have a base diameter of 20–30 μm and height of about 1.5–3 μm. The GaN layers are of the wurtzite type and epitaxially oriented to the sapphire substrate. Beside the threading dislocations, hexagonal rods of GaN surrounded by inversion domain boundaries are observed. An AlN layer has been formed at the interface region during the nitridation process of sapphire.

The interface of Fe-B multilayers was studied by Mossbauer spectroscopy, X-ray diffraction and transmission electron microscopy. The interface region is amorphous and consumes 2n mfrom the iron layer. The same hyperfine field distribution is observed within the amorphous interface when the individual layer thicknesses exceed the width of the inter- face. The width of this distribution is much larger than those measured in amorphous Fe-B alloys and the excess width is attributed to concentration distribution along the interface. On the contrary, the amorphous component in samples with smaller layer thicknesses is more homogeneous as deduced from the hyperfine field distributions, and the hyperfine pa- rameters depend on the ratio of the iron and boron layer thicknesses. Solid state amorphization during the sample de- position is assumed to account for this behavior. Diffusion amorphization is also detected when low-temperature heat treatment of the large layer thickness samples is performed. Single-phase amorphous alloy is formed in both cases in a limited concentration range around 40 at% boron in agree- ment with the predictions of free-energy diagrams.

Mixtures of aluminium and other metal powders were milled in a Hosokawa AM-15F mechanofusion system in order to produce composite materials with coated or layered microstructure. These composites were then annealed or used in plasma spraying experiments. The intermetallic phases produced in the consecutive steps of the treatment were investigated by different methods.

Authors report a very rare case of splenic vein aneurysm in a 34-year-old female patient. She underwent investigation for upper abdominal pain which was not related to eating. Diagnostic workup revealed a thin wall saccular splenic vein aneurysm of 40 mm in diameter which caused an indentation of the posterior wall of the pancreas. She underwent surgery, a tangential resection was carried out preserving the continuity of the splenic vein and spleen. The patient had an uneventful postoperative course and she was discharged on the 5th postoperative day.

Mixtures of aluminium and nickel powders were milled in a Hosokawa AM-15F mechanofusion system in order to produce composite materials with coated or layered microstructure. These composites were then annealed or used in plasma spraying experiments. The intermetallic phases formed in the consecutive steps of the treatment were investigated by means of different methods: electron probe microanalysis (EPMA), transmission electron microscopy (TEM), electron diffraction (ED), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The presence of the intermetallic phases confirmed that phase forming solid state reactions start during the mechanofusion treatment. After milling the powder mixture in the Hosokawa equipment, the crystalline Al 3 Ni could be detected by TEM. A second intermetallic phase, Al 3 Ni 2 was also observed after a heat treatment at 750 K. The microanalytical capabilities of TEM are essential for these investigations. The similarities and the differences between the reactions taking place in the thin films and the thin and/or small milled particles are discussed.

Light microscopic enzyme histochemistry was employed to study the alterations of acetylcholinesterase (AChE) within lumbosacral ventral horn neurons at survival times of 1, 4, 7, 14, 28, 60, and 90 days after low thoracic spinal cord hemisection in adult rats. The intensity of histochemical staining was quantified using densitometric techniques. Virtually all ventral horn neurons of sham-operated and unoperated animals, which served as controls, displayed intense AChE staining. Hemisection of the spinal cord induced a transient ipsilateral decrease of AChE staining in most neuronal cell bodies and in the neuropil of lamina IX at all segmental levels caudal to the lesion. Quantitative analysis of representative segments revealed a reduction of AChE in the ventral horn during a postoperative (p.o.) period of 1 to 28 days followed by a phase of recovery over the next two months. AChE activity still remained slightly reduced, even at 90 days p.o. The transient decrease in AChE is a well-known metabolic response of axotomized motoneurons. However, the observed changes of AChE reactivity in intact motoneurons ipsilateral and caudal to the hemisection are presumably induced by the interruption of supraspinal descending pathways. These metabolic changes may functionally affect the whole motor unit and be involved in the disturbances of motor function following spinal cord injury.

The formation of the Ni 5 Al 3 phase in L1 0 martensite of Ni 65 Al 35 material can be delayed by using slow quenching rates after the homogenisation of the material. This is of potential interest for the use of Ni-Al as a high temperature shape memory alloy. Based on the present results indicating a strong influence of the quenching rate on the ordering sequence in this material, some difficulties in previous interpretations can be clarified.

Different twinning arrangements in Ni 5 Al 3 plates grown inside the B2 phase in Ni 62.5 Al 37.5 samples are descrubed on the basis of conventional and high resolution electron microscopy images and electron diffraction. The plate morphology is comparable with that of pure 2M martensite plates. The choice of ordered variants within a plate is dictated by the ordering coherency of the twin plane. No dislocations were observed at the primary plate-matrix interfaces. An explanation using the streaking due to aperiodic twinning is given for unexpected reflections.

The formation and growth of Ni{sub 5}Al{sub 3} precipitates found inside an annealed B2 matrix in Ni{sub 62.5}Al{sub 37.5} samples is described on the basis of conventional and high resolution electron microscopy images and electron diffraction patterns. Short anneals introduce three-pointed star shaped precipitates consisting of twin related segments with different variants of the Ni{sub 5}Al{sub 3} structure. Longer anneals result in separate plates growing from these wings and developing microtwinning in order to accommodate stress built-up at the interfaces with the surrounding matrix. Two different growth mechanisms were observed and are discussed. The lattice distortions are found to be much higher in the small precipitates than in the large microtwinned plates.

The controversial hypothesis that intraspinal sprouting by dorsal root axons promotes reinnervation of partially denervated neurons caudal to a low thoracic cord hemisection was re-investigated in rats using quantitative immunohistochemical analysis of the neural specific growth-associated protein B-50 (GAP-43) at postoperative survival times of 3, 10, 21, 42, and 90 days. The lack of increase in B-50-immunoreactivity in all segments below the hemisection at all survival times does not support the concept of intraspinal sprouting following the removal of supraspinal descending pathways.

Equiatomic composition powder mixture of pure Fe and B was mechanically alloyed in a controlled atmosphere vibration mill. Amorphous alloy phase formation was established by Mossbauer spectroscopy and by transmission electron microscopy. The variation of the average boron concentration and the homogeneity of the amorphous phase during the alloying process was followed by Mossbauer spectroscopy. At the early stage of the milling process a broad concentration distribution (from 20 to 50 at. % B) was observed. Upon further milling the average B concentration of the amorphous component was gradually enhanced and the concentration heterogeneity decreased. The B concentration of the amorphous phase could be further enhanced by heat treating the milled powder mixture. The highest boron content alloy attained in this study is Fe60B40.

Ti(40nm)/Au(120nm) contacts have been prepared on n-GaN/sapphire. The contacts were annealed from 400?C to 900?C for 10min in nitrogen, respectively. The interaction between the contact metallization and the GaN epitaxial layer (on sapphire) was investigated by electron microscopy and X-ray diffraction. It was found that for an annealing at a temperature equal or higher than 700?C, the gold diffused through Ti layer and Au-rich grains were formed under this Ti layer. Between the Au-rich grains and the n-type GaN layer a new Ti-rich thin layer was identified by XTEM. High resolution images and X-ray data showed that it is TiN0.26 that was formed at the metal/semiconductor interface. FESEM investigations showed that Ti/Au contacts annealed in nitrogen still have a very smooth surface morphology. Ti(40nm)/Au(120nm) contacts have been prepared on n-GaN/sapphire. The contacts were annealed from 400?C to 900?C for 10min in nitrogen, respectively. The interaction between the contact metallization and the GaN epitaxial layer (on sapphire) was investigated by electron microscopy and X-ray diffraction. It was found that for an annealing at a temperature equal or higher than 700?C, the gold diffused through Ti layer and Au-rich grains were formed under this Ti layer. Between the Au-rich grains and the n-type GaN layer a new Ti-rich thin layer was identified by XTEM. High resolution images and X-ray data showed that it's TiN0.26 that was formed at the metal/semiconductor interface. FESEM investigations showed that Ti/Au contacts annealed in nitrogen still have a very smooth surface morphology.

Cr/Au (40/65 nm) metal layers have been deposited by thermal evaporation onto n-GaN epitaxial layers grown by metal-organic chemical-vapour deposition (MOCVD) on a sapphire substrate. The samples have been annealed at 400, 700 and 900 °C for 10 min in vacuum. Techniques of TEM, EDS, HRTEM, FESEM, XRD and I–V characteristics have been used to characterize the micro-, and nanostructure, morphology, composition and electrical properties of the contacts before and after annealing. A binary phase of Cr 3 Ga 4 and Au 7 Ga 2 were identified at the interface of the n-GaN/Cr/Au contacts after annealing in vacuum at 700 and 900 °C. Current-voltage characterizations showed that the as-deposited and annealed Cr/Au contacts are rectifying up to 600 °C. After heat treatment in vacuum at 700 °C and 900 °C the Cr/Au contacts were linear.

Al and Sn were deposited simultaneously by applying two W evaporation sources. The structural evolution of codeposited layers was studied on amorphous (amorphous C films and oxidized Si wafers) and single-crystal (air-cleaved NaCl and mica) substrates at a temperature of 200 C and at various oxygen partial pressures. The codeposition of Sn enhances the self-surface diffusion of Al as well as the liquid-like coalescence of Al crystals, and decreases the sensitivity of structure evolution againts O 2 Sn is segregated during the growth of Al crystals and forms three-dimensional particles. In O 2 atmosphere a solid phase layer develops on the surface of growing Al crystals and the deposition proceeds by the formation of a line-grained. “cermet” like structure.

Serum creatinine, immunoreactive serum and urine β2-microglobulin, plasma and urine thromboglobulin, plasma thromboxane-B2 levels and daily protein excretion were determined in 61 insulin-treated diabetic patients, comparing the different patient groups (complication free, nephropathy without and with azotaemia) with control subjects. In the groups of diabetic patients, plasma and urine β-thromboglobulin (BTG) and plasma thromboxane-B2 levels were higher than in the controls. There was a significant positive correlation between urine BTG and β2-microglobulin in the group without complication, and between the plasma BTG and β2-microglobulin, and plasma BTG and thromboxane levels in the diabetic group with azotaemia. In contrast to some previous assumptions, the increased level of plasma BTG reflects a real platelet hyperactivation in patients with diabetic nephropathy. At the same time, urine BTG also increases. Determination of urine BTG is more simple with less possibility of methodological error.

Single-crystal hexagonal and cubic GaN thin films have been grown by radio-frequency nitrogen plasma source molecular beam epitaxy directly on vicinal (001) GaAs substrates, misoriented by 2° toward [100], without using an incident As beam during oxide desorption or the following stages of growth. Both the GaAs nitridation and GaN growth conditions were found to control the structure of the layers. Cubic layers could be grown only without nitridation and under stoichiometric N/Ga flux ratio conditions. N-rich conditions favored the growth of hexagonal layers, which exhibited significantly higher photoluminescence intensities compared to cubic ones. Hexagonal single crystalline GaN films were grown with (1012) planes and presented characteristic surface roughness striations along a 〈110〉 substrate direction. On the contrary, a stepped surface morphology was observed for cubic GaN.

Al(60 nm) and Ti(40 nm)/Al(160 nm) metal layers have been deposited by thermal evaporation onto n-GaN epitaxial layers grown by metal organic chemical vapour deposition (MOCVD) on a c-plane sapphire substrate. The samples have been annealed at 300, 400, 700 or 900 °C for 10 min in vacuum. The microstructural and electrical properties of the contacts have been investigated by electron microscopy, X-ray diffraction and by current–voltage measurements. As-deposited Al and Ti/Al contacts were rectifying with Schottky barrier heights below 0.35 eV and 0.38 eV, respectively. After heat treatment at 300 °C and 400 °C both contacts exhibited linear current–voltage characteristics. After annealing at 700 °C Al contacts became rectifying with a barrier height of 0.42 eV, while Ti/Al contacts remained nearly linear at the same temperature. The electrical characteristics and XRD analysis indicated that the upper metal in Ti/Al contact diffused in the Ti layer already during deposition. Cross-sectional transmission electron microscopy revealed that in the case of Ti/Al contacts, the continuity of the Ti layers ceased when annealing above 700 °C. X-ray diffractions showed, that a Ti 2 N interface phase formed in Ti/Al contacts at 700 and 900 °C, and an AlN interface phase developed in the same contact at 900 °C.

The transient appearance of 5'-nucleotidase, an adenosine-producing ecto-enzyme, was studied during specific stages of postnatal synaptogenesis in the rat cerebellum. For ultrastructural detection of 5'-nucleotidase activity, an enzyme-cytochemical technique was used. Between postnatal days 4 and 6, enzymatic reaction product was present in the synaptic clefts of climbing fibers containing the perisomatic spines, apical cones and emerging dendrites of Purkinje cells (CF-PC synapses). Labeled parallel fiber synapses were observed on dendritic shafts of cerebellar interneurons. At postnatal days 9 and 12, enzyme-positive parallel fiber terminals were in addition numerous on the spines of peripheral Purkinje branchlets, and gradually disappeared thereafter. Between postnatal days 8 and 15, labeling of perisomatic CF-PC contacts persisted. In contrast, climbing fiber synapses on Purkinje dendrites were only occasionally labeled. Between postnatal days 18 and 21, synaptic reaction product was restricted to mossy fibers. At the same time, association of 5'-nucleotidase with glial profiles was prominent throughout the cerebellar layers. In adult cerebellum (from 24 days onwards) all synapses were devoid of enzymatic activity. Throughout development, basket, stellate and Golgi cell synapses were devoid of enzymatic activity. We conclude that 5'-nucleotidase is present in excitatory cerebellar synapses during part of their generation period. The transient nature of this phenomenon suggests that 5'-nucleotidase may serve as a novel, cytochemical marker for a specific state of synaptic maturation, and in particular for climbing fiber plasticity. A role of 5'-nucleotidase in purinergic neuromodulation and cellular contact formation could be significant in these processes.

This work reports on the development of composite substrates, realised using the Smart Cut™ technology. A thin film of monocrystalline SiC or Si is transferred onto polycrystalline SiC. Those composite substrates can be prepared for 4” size and over as well. GaN layers are grown onto the above substrates in order to demonstrate that they can be used for the fabrication of GaN high electron mobility transistor (HEMT) devices. The epitaxial nitride layers have been grown successfully and exhibit state of the art GaN HEMTs grown on silicon in terms of crystal and electrical properties.

GaN based high electron mobility transistor structures were grown onto special composite substrates by metal-organic chemical vapor deposition. These substrates consist of a thin single crystalline SiC layer transferred onto polycrystalline SiC wafer by a technique involving ion implantation and wafer bonding. Transmission electron microscopy of these structures has proven that their epitaxial quality and defect structure is the same as of the reference samples deposited onto single crystalline bulk SiC substrate.

The full performance of GaN devices for high power applications is not exploited due to their self-heating. Possible solutions are the integration of materials with high heat conductivity i.e., single crystalline diamond and graphene layers. We report the growth of single crystalline (0001)-oriented GaN thin films on (100), (110) and (111) diamond single crystals studied by transmission electron microscopy (TEM) in cross-sections. As for graphene, we show a high quality GaN layer that was deposited on patterned graphene layers and 6H-SiC. The atomic structures of the interfaces in the heterostructure are studied using aberration-corrected scanning TEM combined with energy dispersive x-ray and electron energy-loss spectroscopy. Funding Agencies|OTKA project (Hungary) [K 108869]; European Union under the Seventh Framework Program [312483 ESTEEM2]

ZnSe/Zn0.75Cd0.25Se quantum wells have been grown on GaAs submicron gratings. In these quantum structures, we observe an optical anisotropy induced by lateral confinement. Photoluminescence (PL) energy-shifts and the PL temperature dependence indicate a moderate modulation of the two-dimensional electron gas in the quantum well.

Stromal tumors of the gastrointestinal tract are rare mesenchymal neoplasms. The majority of them are appearing in the stomach: their quite common first manifestation is bleeding. The authors report a case of polypoid gastric GIST causing severe bleeding which needed urgent surgical intervention and partial resection of the stomach. Although histological analysis of the tumor revealed low proliferation rate, the urgent operation did not result in a complete eradication of the neoplasm, thereby our patient needs further follow-up and treatment.

The CO content of hydrogen feed to proton-exchange membrane fuel cells (PEMFCs) must be kept under 1–100 ppm for their proper operation. This can be achieved by using catalysts able to selectively oxidize CO in the presence of excess hydrogen (PROX). The present study reports on the mechanism of the PROX reaction on Pt/CeO2 catalyst, using catalytic tests, in situ DRIFTS, high-pressure XPS, HRTEM, and TDS techniques. Bulk metallic, pronounced adsorbate-induced surface Pt, and a small amount of oxidized Pt sites were detected by in situ high-pressure XPS under PROX conditions. The preoxidized ceria surface was strongly reduced in pure H2 but significantly reoxidized under PROX conditions (i.e., O2 + CO in excess hydrogen) at T = 358 K . The remaining small amount of Ce3+ decreased with increasing temperature. HRTEM found well-crystallized CeO2 particles (8–10 nm) in the case of activated (pre-oxidized) sample that transformed in a large extent to an oxygen deficient ceria supercell structure after PROX reaction. Metallic Pt particles (2–3 nm) and small (0.5–0.6 nm) Pt clusters were found by HRTEM. These findings were in accordance with the variations in relative intensity of the corresponding Pt CO bands (DRIFTS). Different types of carbonate and formate species were detected (XPS and DRIFTS). Their possible role in the reaction mechanism is discussed. Resolved OH bands could not be found by DRIFTS in the PROX reaction mixture indicating significant amount of adsorbed water in a hydrogen-bonded structure. Its presence seems to suppress hydrogen oxidation while CO oxidation still takes place, as the metallic particles are covered by CO (DRIFTS). The direct contribution of surface water in a low-temperature water–gas shift-type reaction in the PROX mixture is proposed.

The aim of the PROX reaction is to reduce the CO content of hydrogen feed to proton exchange membrane fuel cells (PEMFC) by selective oxidation of CO in the presence of excess hydrogen. Both Pt and Pd on ceria are active in CO oxidation (without hydrogen) while Pd is poorly active in the presence of hydrogen. In this paper we aimed at finding the reasons of such behavior, using the same techniques for Pd/CeO2 as for Pt/CeO2 in Part I: catalytic tests, in-situ DRIFTS, high-pressure XPS, HRTEM and TDS. The reaction mechanism of CO oxidation (without hydrogen) was also examined. It does not occur via the exactly same mechanism on Pt and Pd/CeO2 catalyst. In the presence of hydrogen (PROX) at low temperature (T=350-380 K), the formation of Pd β-hydride was confirmed by high-pressure in-situ XPS. Its formation greatly suppressed the possibility of CO oxidation, because oxygen both from gas phase and support sites reacted fast with hydride H to form water, and this water desorbed from Pd easily. Nevertheless, CO adsorption was not hampered here. These entities transformed mainly to surface formate and formyl (-CHO) species instead of oxidation as observed by DRIFTS. The participation of a low-temperature water-gas-shift type reaction proposed for the platinum system [Part I] was hindered. Increasing temperature led to decomposition of the hydride phase and a parallel increase in the selectivity towards CO oxidation was observed. However, it remained still lower on Pd/CeO2 than on Pt/CeO2.

The aim of the study was to test the hypothesis that in diabetic patients without overt nephropathy there may be a correlation between the activity of natural anticoagulant proteins and glomerular dysfunction. Assays for functional activity of proteins S and C, measurements of urinary albumin excretion, lipid parameters and haemoglobin A1c were performed in 91 patients with type 1 diabetes mellitus and 85 patients with type 2. Patients with type 1 diabetes and microalbuminuria had significantly higher mean age (44.1 +/- 10.9 vs. 37.9 +/- 12.7 years; p0.05), fibrinogen level (3.75 +/- 1.0 vs. 3.21 +/- 0.8 g/l; p0.01), protein S activity (92.3 +/- 17.6 vs. 84.5 +/- 15.5%; p0.05) and higher prevalence of retinopathy (p0.01) and macrovascular disease (p0.01) than those with normoalbuminuria. Albumin excretion was significantly correlated to age (r=0.25, p0.05), fibrinogen level (r=0.39, p0.01), protein S activity (r=0.27; p0.05), total cholesterol (r=0.23; p0.05), apoprotein B (r=0.22; p0.05), retinopathy (r=0.33; p0.01) and macrovascular disease (r=0.33; p0.01). Patients with type 2 diabetes mellitus and microalbuminuria had significantly higher apoprotein B levels (1.17 +/- 0.3 vs. 1.06 +/- 1.2 mg/dl; p0.05) than those with normoalbuminuria, and apoprotein B was significantly correlated to albumin excretion (r=0.22; p0.05). In a multivariate model of type 1 diabetes mellitus with fibrinogen, protein S and C activity, cholesterol, triglycerides, haemoglobin A1c, retinopathy, and macrovascular disease as independent parameters (r=0.53; p0.003), there was significant independent correlation of fibrinogen (beta=0.28; p0.01), protein S activity (beta=0.27; p0.05) and retinopathy (beta=0.21; p0.01) with albumin excretion. We conclude that in type 1 diabetes, relative elevation of fibrinogen level and protein S activity appear in the early stages of development of diabetic nephropathy, and may be related to the pathogenesis of diabetic kidney disease.

Cubic SiC is implanted with carbon ions at 600, 900, 1100 and 1200 °C. X-ray diffraction and transmission electron microscopy revealed the influence of implantation temperature and dose rate on the formation of graphite and diamond precipitates, respectively. The high dose carbon implantation at 600 °C yields graphite already in a textured form. Spherical diamond grains, which are always epitaxial to the SiC, are found in samples implanted at 900 °C or higher. Increasing the dose rate leads to formation of graphite instead of diamond at 900 °C as well. Hence, a critical temperature for diamond evolution exists, which depends on dose rate. Size and shape of the formed diamond precipitates is not influenced by dose rate within the investigated range. Increasing the fluence results in bigger diamond nanocrystals, which are bordered by facets.