Search

Industry 4.0 technologies can improve not only the performance of manufacturing and assembly processes, but also the efficiency of related logistic operations can be increased. Within the frame of this article a system is shown for identifying product mixing problems using RFID technologies. Firstly, the laboratory is introduced, where the technology is used. The identification of loading unit building equipment and products is based on RFID tags. We used Excel format database file to hold the binding matrix of the products. We have developed a software that controls our industrial IF30 RFID reader. Our software performs a product mix detection test as well. The paper highlights also the future research directions.

Abstract: Benign multicystic peritoneal mesothelioma is a rare benign tumor originating from the peritoneum, affecting mostly young, fertile women. Its presentation is non-specific, thus the final diagnosis is made after the histological examination. A young female patient presented with incarcerated inguinal hernia of which an emergency surgery was performed. During the operation a cystic mass neighboring the round ligament in the canal of Nuck was removed. No inguinal hernia was found. The histological examination confirmed the diagnosis of benign multicystic mesothelioma. The patient was referred to a center performing hyperthermic intraperitoneal chemotherapy, where laparoscopic exploration was performed. The second surgery revealed no residual tumor or any other pathology. A 41-year-old male patient, 4 years before presenting at our ward, had an elective umbilical hernia repair surgery. During the operation 2 cm big cystic mass was removed from the peritoneum, and the histological examination revealed benign multicystic mesothelioma. In 2018, acute surgery was performed due to a periappendicular abscess, while during the surgery a multicystic mass situated on the distal end of the appendix was also removed. The pathological finding confirmed the recurrence of the first tumor. The radiological examination did not find any signs of residual tumor mass anywhere else. The chances of malignant transformation in cases of benign multicystic peritoneal mesothelioma are low. The suggested treatment is en bloc surgical removal of the mass, however, in these cases recurrence is still 50%. If during follow-ups the recurrence of the tumor is found, a total peritonectomy or hyperthermic intraperitoneal chemotherapy is advisable. Orv Hetil. 2019; 160(21): 839–843.

In this paper, the advantages of GaN high electron mobility transistors (HEMTs) grown on native GaN over GaN/Si or GaN/sapphire substrates are investigated and correlated with epitaxial material quality. Transmission electron microscopy plan-view and cross-sectional analyses of GaN/GaN reveal dislocation densities below ${1} \times {10}^{{6}}$ cm−2, which is at least three orders of magnitude lower than that of GaN/Si or GaN/sapphire. In the case of GaN/Si, the dislocations not only originate from the substrate/nucleation layer interface, but also the strain relief and isolation buffer stacks are main contributors to the dislocation density. GaN/GaN HEMTs show superior electrical and thermal performance and feature three orders of magnitude lower OFF-state leakage. The current collapse (also referred to as current dispersion or $R_{ \mathrm{\scriptscriptstyle ON}}$ -increase) after stress bias is less than 15% compared with 50% in the case of GaN/Si. A 2% drop of the ON-state current due to self-heating in dc operation when compared with 13% and 16% for GaN/Si and GaN/sapphire, respectively. The GaN/Si thermal performance becomes comparable to that of GaN/GaN only after substrate removal. Therefore, GaN/GaN provides high ON-state current, low OFF-state leakage current, minimal current collapse, and enhanced thermal power dissipation capability at the same time, which can directly be correlated with the absence of high dislocation density.

In this work, we investigate the formation of the inverted technology created quantum dot by a method based on droplet epitaxy. The preparation process of the so called inverted quantum dot is carried out with the filling of the nano-hole. The investigated GaAs dot is embedded in AlAs/AlxGa1 − xAs multilayer structure. Transmission electron microscopy investigation shows that the quantum structure is perfectly crystalline and fits very well to the crystal structure of the base layer. The nano-hole has a hill around its opening. Furthermore, the sides of the nano-structure consist of low Miller index facets. The filling process results formation of a hill over the nano-hole. The elemental mapping shows Al immigration into the GaAs layer. Formation of the hill after the filling process and the Al immigration are also explained in this paper. Temperature dependent photoluminescence spectra were measured in the range of room temperature and 4.7 K. The electronic structure given from photoluminescence spectroscopy is explained.

Polarization engineering is a promising approach to achieve high positive threshold voltage (Vth) in GaN-based metal-oxide-semiconductor high electron mobility transistors (MOS HEMTs). In this paper, we investigate all critical interfaces of polarization-engineered normally-off Al2O3/InGaN/AlGaN/GaN MOS HEMTs using transmission electron microscopy and X-ray photoelectron spectroscopy. Mechanisms of threshold voltage ( V TH ) instabilities are also analyzed. Devices were subjected to positive-bias stress-recovery experiments to capture the transient change in Vth. We propose a model that explains observed peculiar behavior and discuss the role of 2-dimensional hole gas (2DHG) in Al2O3/InGaN/AlGaN/GaN MOS HEMTs Vth shift.

In this work, we are dealing with a novel technology, called droplet epitaxy, which is useful technique when quantum dots are to be produced, of different shape and size in various densities. There are self-assembling methods to achieve quantum dot ensembles and their spatial ordering and positioning. Their evolution kinetic is very important to handheld the self-assembling. After the discussion of the growth mechanism, we are dealing some of self-assembled quantum dot arrangement in the view point of realization of nano-electronics.

3C-SiC have been implanted with carbon ions at 60 keV to a dose of 3x10^17 and 1x10^18 cm^-2. All of the implantation experiments were carried out at elevated temperature in the range of 900°C-1200°C to study the phases, which are formed, when excess carbon is introduced into the SiC lattice. At 1100^C and at 1200°C small diamond grains are formed; these are embedded in the SiC and form perfectly oriented crystallites of a few nm size. Diamond is formed in SiC at 900°C as well, however, at high dose rate the impinging carbon ions can destroy the nucleated diamond grains.

A hybrid metal?semiconductor nanosystem for the generation of THz radiation, based on the fabrication of GaAs quantum molecules-Ga metal nanoparticles complexes through a self assembly approach, is proposed. The role of the growth parameters, the substrate temperature, the Ga and As flux during the quantum dot molecule (QDM) fabrication and the metal nanoparticle alignment are discussed. The tuning of the relative positioning of QDMs and metal nanoparticles is obtained through the careful control of Ga droplet nucleation sites via Ga surface diffusion. The electronic structure of a typical QDM was evaluated on the base of the morphological characterizations performed by atomic force microscopy and cross sectional scanning electron microscopy, and the predicted results confirmed by micro-photoluminescence experiments, showing that the Ga metal nanoparticle-GaAs quantum molecule complexes are suitable for terahertz generation from intraband transition.

Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al2O3–Ta2O5 nanolaminate, AlxTayOz mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing.

In this study we report on the micro-, and nanostructural, morphological and electrical properties of Ti(20 nm)/Cr(120 nm)/Al(50 nm) contacts to n-GaN by electron microscopy, X-ray diffraction and I – V measurements. Tested contacts were annealed at the temperature of 400, 700 and 900 °C for 10 min in vacuum. It was found that Cr appeared in the top part of the GaN epitaxial layer at 700 °C. High resolution electron microscopy (HREM) revealed Ti 2 AlN MAX phase as well as Al 2 O 3 phase at the interface of n-GaN/Ti/Cr/Al contact at 900 °C. X-ray diffraction examinations showed that new Ti 2 AlN MAX phase formed and Cr 3 GaN as well as CrN phases developed at 900 °C. I – V characterizations exhibited that while the as-deposited and annealed Ti/Cr/Al contacts are rectifying up to 700 °C the diffusion of Cr into the epi GaN layer led to ohmic behaviour at 700 °C.

Atomic layer deposition (ALD) is a thin film deposition technique that is based on alternating and saturating surface reactions of two or more gaseous precursors. The excellent conformality of ALD thin films can be exploited for sealing defects in coatings made by other techniques. Here the corrosion protection properties of hard CrN and diamond-like carbon (DLC) coatings on low alloy steel were improved by ALD sealing with 50 nm thick layers consisting of Al2O3 and Ta2O5 nanolaminates or mixtures. In cross sectional images the ALD layers were found to follow the surface morphology of the CrN coatings uniformly. Furthermore, ALD growth into the pinholes of the CrN coating was verified. In electrochemical measurements the ALD sealing was found to decrease the current density of the CrN coated steel by over 2 orders of magnitude. The neutral salt spray (NSS) durability was also improved: on the best samples the appearance of corrosion spots was delayed from 2 to 168 h. On DLC coatings the adhesion of the ALD sealing layers was weaker, but still clear improvement in NSS durability was achieved indicating sealing of the pinholes.

The proposal and processing aspects of the prove-of-concept InGaN/GaN/AlGaN/GaN metal-oxide-semiconductor (MOS) high-electron mobility transistor with etched access regions are addressed. Full strain and decent quality of the epitaxial system comprising 4 nm In0.16Ga0.84N/3 nm GaN/5 nm Al0.27Ga0.73N are observed using a high-resolution transmission-electron microscopy and by deformation profile extractions. Large negative polarization charge in the MOS gate stack provides the HEMT normally-off operation, while free electrons are populated at access regions after etching. Consecutive passivation by 10 nm Al2O3 together with annealing at 300 °C improved the Al2O3/semiconductor interface, with the threshold voltage (V T ) reaching 1 V. Improvements of the present concept in comparison to the previous one with a gate recess were proved by showing the decreased drain leakage current and increased breakdown voltage.

Atomic layer deposited (ALD) 50nm AlxTayOz mixture coatings are grown on steel for corrosion protection. In morphological and compositional analyses the coatings are found to be uniform, conformal, well-adhered, and low in defect density. Corrosion protection properties are evaluated with polarization measurements and neutral salt spray (NSS) testing. The sealing properties of the mixtures improve with increasing aluminum oxide content, whereas the protection durability improves with increasing tantalum oxide content. In comparison to single-layer and nano-laminate ALD Al2O3 and Ta2O5 coatings, all mixtures are found to have better protective properties.

The effect of H2–Ar plasma pre-treatment prior to thermal atomic layer deposition (ALD) and plasma-enhanced atomic layer deposition (PEALD) of Al2O3 films on steel for corrosion protection was investigated. Time-of-flight secondary ion mass spectrometry and transmission electron microscopy were used to observe the changes in the interface. The electrochemical properties of the samples were studied with polarization measurements, and the coating porosities were calculated from the polarization results for easier comparison of the coatings. Prior to thermal ALD the plasma pre-treatment was observed to reduce the amount of impurities at the interface and coating porosity by 1–3 orders of magnitude. The anti-corrosion properties of the PEALD coatings could also be improved by the pre-treatment. However, exposure of the pre-treatment plasma activated steel surface to oxygen plasma species in PEALD led to facile oxide layer formation in the interface. The oxide layer formed this way was thicker than the native oxide layer and appeared to be detrimental to the protective properties of the coating. The best performance for PEALD Al2O3 coatings was achieved when, after the plasma pre-treatment, the surface was given time to regrow a thin protective interfacial oxide prior to exposure to the oxygen plasma. The different effects that thermal and plasma-enhanced ALD have on the substrate-coating interface were compared. The reactivity of the oxygen precursor was shown to have a significant influence on substrate surface in the early stages of film growth and thereafter also on the overall quality of the protective film.

The charging behaviour of MNS (metal-nitride-silicon) and MNOS (metalnitride- oxide-silicon) structures containing Si or Ge nanocrystals were studied by capacitance-voltage (C-V) and memory window measurements and by simulation. Both the width of hysteresis of C-V characteristics and the injected charge exhibited exponential dependence on the charging voltage at moderate voltage values, while at high voltages the width of hysteresis of C-V characteristics and the injected charge exhibited saturation. The memory window for reference MNS structure without nanocrystals was wider than that for reference MNOS structures. The presence of nanocrystals enhanced the charging behaviour of MNOS structures, but in MNS structures nanocrystals exhibited the opposite effect. The main conclusion is that the presence of nanocrystals or other deep levels close to the Si surface enhances the charge injection properties due to the increased tunneling probability, but nanocrystals or other deep levels located far from the Si surface in the nitride layer do not enhance, but even can degrade the charging behaviour by the capture of charge carriers.

This paper reports the direct growth by MOVPE of high-quality, crack-free III-nitrides (∼350 nm) on composite substrates comprising an ultra-thin Si (111) layer on which polycrystalline diamond (PD) has been deposited. The Si/PD substrates are designed to provide superior heat sinking performance for high power devices. The FWHM of rocking curves of the nitride films is measured to be ∼1100 arcsec from a GaN/Al0.2Ga0.8N/AlN/Si/PD multilayer structure. As expected from the low coefficient of thermal expansion of diamond, the epitaxial layers are under severe tensile stress. The Si (111) layer is shown to act as a compliant buffer layer between the III-nitride and the PD, i.e. the Si is under a compressive stress under the influence of GaN of larger thermal expansion coefficient, but the structure is mechanically stable. This technique is an obvious economic and technological advantage compared to direct growth of III-nitrides on single crystal diamond (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We investigate strain-free GaAs quantum dots (QDs) fabricated by filling of nanoholes in semiconductor surfaces. The nanoholes are created in a self-organized fashion by local droplet etching with Al droplets as etchants. High resolution transmission electron microscopy (TEM) demonstrates that the quantum dots are free of extended defects. Elemental mapping using local electron energy loss spectroscopy (EELS) shows that the walls surrounding the nanohole openings consist of AlAs. This result confirms that the walls are optically inactive.

In this work, droplet epitaxially grown GaAs quantum dots on AlGaAs surface are studied. The quantum dots are investigated in situ with RHEED and ex situ with TEM method. The TEM picture shows that the quantum dot is perfectly crystalline and fits very well to the crystal structure of the substrate. Furthermore, the side of the quantum dot shows stepped facet shape. Here, we show, how the stepped side shape forms from the droplet during crystallization. The RHEED picture shows broadened chevron-tail, which can be explained by the shape of the quantum dot.

In this work the technology and characterization of nanocrystalline diamond (NCD) films directly grown on InAlN/GaN HEMTs is presented. Optimization of GaN based HEMT process steps including metallization stacks is discussed. A fully processed InAlN/GaN HEMT structure with 7 nm barrier has been overgrown in a temperature range of 750 degrees C to 800 degrees C with a 500 nm thick nanocrystalline diamond film in a Hot Filament CVD system. First results of semi-enhancement mode of DC and RF HEMT operation are reported. The grown NCD films were characterized by SEM, TEM, and Raman spectroscopy. Although no direct thermal conductivity measurements are conducted yet; the performed experiments shows the compatibility of growing high quality NCD films, several microns thick. on InAlN/GaN HEMTs as a potential material for heat extraction purposes. (C) 2011 Elsevier B.V. All rights reserved.

We have employed plasma-enhanced and thermal atomic layer deposition (ALD) within the temperature range of 50-150°C for the deposition of ultra-thin (10-50 nm) Al 2 O 3 films on 100Cr6 steel and aluminium Al2024-T3 alloys. [Al(CH 2 ) 3 ] was used as the precursor with either an O 2 plasma or water as co-reactants. Neutral salt spray tests showed that the thicker films offered the best corrosion-resistance. Using cyclic voltametry, the 50 nm films were found to be the least porous (

In this work we have investigated the thermal oxidation of thin InAlN/GaN heterostructures in their lattice matched configuration (83% Al) in oxygen atmosphere at 800 °C. TEM cross sections revealed a partially crystalline oxide with an initial oxidation rate of 0.37 nm/minute. MOS diodes fabricated using the thermal oxide as a gate dielectric showed an exponential drop in the gate leakage which scales with the square root of oxidation time indicating diffusion limited oxidation through the InAlN barrier. The effect of oxidation on the interfacial InAlN/GaN sheet charge density (NS) is correlated with a reduction of thickness for short oxidation times (up to 4 min) and an abrupt change in the surface potential for longer oxidation times. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The factory wanted to know what state was the equipment in the refuse conveying in. On the indicated machines we have conducted vibration diagnostics. We evaluated the measurement results with the help of the software on a computer. We have detected a flaw in the bearing of the extractor. The vibration quantity was optimal at the biggest motor. All bearings were in good condition. We sent the results to the factory, and recommended modifying the setting of one strap foldings for the interest of the vibration strength. We proposed the correction of the lubri-cant on the bearings.

Unsupported and SiO2 supported GePt bimetallic catalysts were prepared by depositing Ge on to Pt underpotentially. Surface-sensitive cyclic voltammetry of Pt black indicated that Ge covered ca. 40–45% of the Pt surface, whereas XPS showed just ∼96% Pt and ∼4% Ge (normalized to Pt + Ge = 100 % ). High-resolution Ge map of GePt black obtained by Energy Filtered TEM (EFTEM) showed Ge scattered in the near-surface regions. Both catalysts were tested in hexane (nH) transformation reactions between 543 and 603 K and 60 to 480 Torr H2 pressure (with 10 Torr nH), and compared with the parent Pt catalysts. GePt/SiO2 catalyst was also tested with methylcyclopentane (MCP). Adding Ge to Pt/SiO2 lowered the activity; the opposite effect was observed with GePt black. The selectivities of saturated products on bimetallic catalysts decreased, while those of hydrogenolysis products, benzene and hexenes increased in nH transformations over supported catalyst. The reverse effects were observed over the black samples where addition of Ge prevented accumulation of adventitious carbon. Ring opening was the main reaction with MCP, together with some fragments, benzene and unsaturated hydrocarbons. Ring opening of MCP became more selective with decreasing temperature and increasing hydrogen pressure. Ge on GePt black blocked contiguous Pt sites favoring the formation of coke precursors. The different catalytic behavior of GePt/SiO2 indicated somewhat different Pt–Ge interaction(s).

This paper reports on low-pressure metalorganic vapour deposition (LP-MOCVD) growth optimisation of GaAlN/GaN heterostructures grown on SiCopSiC (silicon carbide-oxyde-polycrystalline silicon carbide) composite substrates for HEMT applications, and on the first device performances obtained with these structures. Some critical growth parameters, such as growth temperature, V/III ratio and nucleation layer at the GaN/SiC interface, have been investigated, and their impact on physical properties of these heterostructures is studied. Such optimisation of the growth conditions has led to GaAlN/GaN HEMT heterostructures which are successfully compared in terms of material quality to the standard HEMT heterostructures grown on bulk SiC substrates. Their electrical characteristics, such as sheet carrier density ( N s ), mobility ( μ ), pinch-off voltage ( V p ) or sheet resistance ( R s ), are very similar to those obtained on bulk SiC substrates and their crystallographic properties, assessed by high-resolution X-ray diffraction (HR-XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM), seem to be in good agreement with the above-mentioned electrical characteristics. First devices with 0.5 μm gate length, made on these specific composite wafers, exhibit very good microwave performances, with output power of 5 W/mm at 10 GHz, similar to those obtained on bulk SiC substrates, showing the promising capability of SiCopSiC composite substrates.

The availability of PET/CT examinations in Hungary has significantly improved in the past few years. In the three Hungarian centres approximately 10,000 examinations can be performed yearly, which are financed by the national healthcare system. The PET/CT technique using FDG has become an efficient tumour diagnostic method due to its outstanding sensitivity and specificity. Similarly to other medical imaging techniques, PET/CT is a useful and cost-beneficial diagnostic modality in the hand of those clinicians, who clearly know its advantages and limitations. In the present paper the most frequent indications of PET/CT examinations are reviewed, with special attention to cases relevant to the everyday surgical practice. The applicability of this technique is also considered.

Au and Ti/Au layers were deposited on n-GaN. The samples were annealed at 400, 700 and 900 °C for 10 min in vacuum. The contacts were rectifying up to 700 °C and the highest Schottky barrier height of 1.07 eV was obtained for an Au single layer by current–voltage measurements. A binary phase of Au2Ga was identified at the interface of the n-GaN/Ti/Au contact after annealing at 900 °C. The formation of Ti2N and TiN (twin) phases epitaxially grown on GaN was also observed in the same contact as well as some gold diffusion into the topmost region of the GaN epilayer.

Memory structures with an embedded sheet of separated Si nanocrystals were prepared by low pressure chemical vapour deposition using a Si3N4 control layer and different SiO2 or Si3N4 tunnel layers. It was obtained that Si nanocrystals improve the charging behaviour of the MNOS structures. Memory window width of 1.3 Vand 2.0 V were obtained for pulse amplitudes of ±9 V and ±10 V, 100 ms, respectively. The extrapolated memory window after 10 years is about 15% of its initial value.

Ge nanocrystals were formed by electron beam evaporation on SiO2 covered Si substrates. The size and distribution of the nanocrystals were studied by atomic force microscopy, scanning electron microscopy and cross-sectional transmission electron microscopy. Dependencies of the nanocrystal size, of the nanocrystal surface coverage, and sheet resistance obtained by van der Pauw method of the Ge layer have been found on the evaporation time. The suggested growth mechanism for the formation of nanocrystals is the Volmer-Weber type. The sheet resistance exhibited a power dependence on the nanocrystal size.

A new method to produce zinc oxide nanocrystals is presented. The method is based on the thermal decomposition of zinc alginate gels. The gels were produced in the form of beads by ionic gelation between a zinc solution and sodium alginate. The wet beads were heated at 800 and 450 °C for 24 h and the products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM) and micro-Raman spectroscopy. XRD analysis showed that all obtained samples are of wurtzite structure. TEM analysis combined with electron diffraction also showed the presence of single crystals indexed as ZnO hexagonal phase. Crystal size was determined by measuring individual crystals from SEM pictures. It was found that heating temperature and the kind of zinc agent influence the crystal size. Raman scattering revealed the existence of defects in the structure of nanoparticles whose cringing was discussed in the context of recent studies in this field.

Rh was deposited on a parent platinum black catalyst by an underpotential deposition method. Mean particle size and bulk composition of this Rh-Pt sample was determined by TEM and EDS. No individual Rh grains could be observed, but Rh was present in the near-surface regions, according to energy-filtered TEM images. The surface-sensitive cyclic voltammetry indicated 15-20% Rh on the surface. XPS, in turn, detected ∼ 2-2.5% Rh in the information depth. The Rh-Pt catalyst was tested in methylcyclopentane hydrogenative ring-opening reaction between 468 and 603 K and 8 to 64 kPa H2 pressure (with 1.3 kPa MCP). The parent Pt black as well as a Rh black catalyst was also studied for comparison. MCP produced ring opening and hydrogenolysis products. The ring-opening products (ROP) consisted of 2- and 3-methylpentane (2MP and 3MP) as well as hexane (nH). These were the main products, together with some fragments and unsaturated hydrocarbons. The amount of the latter class increased at higher temperatures. The selectivities of ROP, fragments, and benzene over Rh-Pt catalyst as a function of temperature were between the values observed on Pt and Rh. The hydrogen pressure dependence of selectivities on Rh-Pt was more similar to that observed on Pt. Four subsequent treatments with O2 and H2 up to T = 673 K were applied on the bimetallic catalyst, followed by XPS and catalytic runs, respectively. These treatments promoted structural rearrangement, with XPS detecting less Rh in the near-surface region, partly as oxidized Rh after O2 treatment. The catalytic behavior became more Pt-like on these structural and composition changes. We concluded that adding a rela- tively small amount of Rh to Pt creates bimetallic active sites with properties different from those of its components, behaving as a true bimetallic catalyst.

Rh was deposited on to a well-characterized 3.1% Pt/SiO2 (InCat-1) parent catalyst by underpotential deposition method to obtain a model Rh–Pt bimetallic catalyst. TEM and EDS was used to determine its mean particle size and bulk composition: the particles of ca. 3 nm contained ca. 60% Pt and 40% Rh. The Rh–Pt catalyst was tested in methylcyclopentane (MCP) reaction between 513 K and 603 K and 60–480 Torr H2 pressure (with 10 Torr MCP). The parent Pt/SiO2 as well as a 5% Rh/SiO2 catalyst were also studied for comparison. Four subsequent treatments with O2 and H2 up to T = 673 K were applied on the bimetallic catalyst before the catalytic runs. The overall activity showed positive hydrogen order on all samples, bimetallic Rh–Pt resulting in the lowest TOF values. Ring opening and hydrogenolysis products, as well as unsaturated hydrocarbons were formed from MCP. The selectivity of ring opening products and fragments over Rh–Pt catalyst was between the values observed on Pt and Rh, while the selectivity towards benzene formation was highest on the bimetallic sample, especially at higher temperatures. “Selective” ring opening occurred on all samples, resulting mostly in 2 and 3-methylpentane and less hexane. Different pretreatments with H2 and O2 affected slightly the dispersion values and the catalytic behavior of Rh–Pt sample. The selectivities of the Rh–Pt catalyst being between the values observed for Pt/SiO2 and Rh/SiO2 indicates that the sample studied represented a real bimetallic catalyst, resembling both components and exhibiting at the same time, new properties in addition to those, characteristic of Pt or Rh.

Low-pressure chemical vapour deposited Si 3 N 4 /nc-Si/Si 3 N 4 layers prepared on Si substrates were characterized by spectroscopic ellipsometry. Model Dielectric Function (MDF) was applied to obtain the thickness and the dielectric spectra of the middle nc-Si layer. Sensitive effect of the deposition time was obtained on the MDF parameters. A comparison is presented between the studied samples and reference materials.

Microwave and power electronics based on GaN enables the performance of systems and their safe operating area to be driven to ‘extremes’. One of the major issues that then arises is thermal management. This includes heat transfer limitations across interfaces, however also the need of incorporating novel high thermal conductivity materials such as diamond. Thermal parameters of these novel device systems and their implications on the near junction temperature in the devices are not well known. The role of interfaces between the GaN transistor and the diamond substrate, and of the diamond thermal properties themselves near this interface are discussed, and novel thermal characterization approaches, such as enabling fast determination of the thermal resistance on the wafer level, as well as of lateral diamond thermal conductivity, are presented.Copyright © 2015 by ASME

The thermal transport in polycrystalline diamond films near its nucleation region is still not well understood. Here, a steady-state technique to determine the thermal transport within the nano-crystalline diamond present at their nucleation site has been demonstrated. Taking advantage of silicon nanowires as surface temperature nano-sensors, and using Raman Thermography, the in-plane and cross-plane components of the thermal conductivity of ultra-thin diamond layers and their thermal barrier to the Si substrate were determined. Both components of the thermal conductivity of the nano-crystalline diamond were found to be well below the values of polycrystalline bulk diamond, with a cross-plane thermal conductivity larger than the in-plane thermal conductivity. Also a depth dependence of the lateral thermal conductivity through the diamond layer was determined. The results impact the design and integration of diamond for thermal management of AlGaN/GaN high power transistors and also show the usefulness of the nanowires as accurate nano-thermometers.

International audience; Al, Au, Ti/Al and Ti/Au contacts were prepared on n-GaN and annealed up to 900 °C. The structure, phase and morphology were studied by cross-sectional transmission and scanning electron microscopy as well as by X-ray diffraction (XRD), the electrical behaviour by current–voltage measurements. It was obtained that annealing resulted in interdiffusion, lateral diffusion along the surface, alloying and bowling up of the metal layers. The current–voltage characteristics of as-deposited Al and Ti/Al contacts were linear, while the Au and Ti/Au contacts exhibited rectifying behaviour. Except the Ti/Au contact which became linear, the contacts degraded during heat treatment at 900 °C. The surface of Au and Ti/Au contacts annealed at 900 °C have shown fractal-like structures revealed by scanning electron microscopy. Transmission electron microscopy and XRD investigations of the Ti/Au contact revealed that Au diffused into the n-GaN layer at 900 °C. X-ray diffraction examinations showed, that new Ti2N, Au2Ga and Ga3Ti2 interface phases formed in Ti/Au contact at 900 °C, new Ti2N phase formed in Ti/Al contact at 700 and 900 °C, as well as new AlN interface phase developed in Ti/Al contact at 900 °C.

Au-TiO(2) interface on silica support was aimed to be produced in a controlled way by use of Au hydrosol. In method A, the Au colloids were modified by hydrolysis of the water-soluble Ti(IV) bis(ammoniumlactato)dihydroxide (TALH) precursor and then adsorbed on Aerosil SiO(2) surface. In method B, Au sol was first deposited onto the SiO(2) surface and then TALH was adsorbed on it. Regular and high-resolution transmission electron microscopy (TEM and HRTEM) and energy dispersive spectrometry (EDS) analysis allowed us to conclude that, in method A, gold particles were able to retain the precursor of TiO(2) at 1.5 wt % TiO(2) loading, but at 4 wt % TiO(2) content the promoter oxide appeared over the silica surface as well. With method B, titania was detected on silica at each TiO(2) concentration. In Au-TiO(2)/SiO(2) samples, the stability of Au particles against sintering was much higher than in Au/TiO(2). The formation of an active Au-TiO(2) perimeter was proven by the greatly increased CO oxidation activity compared to that of the reference Au/SiO(2).

Unsupported Pd, Pt and PdPt bimetallic catalysts were prepared in different atomic ratios using methods of colloid chemistry. They were characterized by XPS, UPS and TEM. Four subsequent treatments with O2 and H2 up to T = 603 K were applied in the preparation chamber of the electron spectrometer and before the catalytic runs. Platinum strongly hindered the oxidation of palladium in the bimetallic samples indicating an alloying of the two components. The H2 treatment after O2 led to rather clean metals. These treatments up to 603 K decreased the Pt enrichment near to the surface found by XPS, destroying presumably the Pt islands on the surface of a Pd-rich matrix. The particle composition approached thus a homogeneous metal mixture. The catalytic behavior was tested in the hydrogenative ring opening reaction of cis- and trans-methyl-ethylcyclopropane (MECP) at 373 K. The product ratios 2-methylpentane/3-methylpentane (2MP/3MP) and 2-methylpentane/n-hexane (2MP/nH) were used to characterize the ring-opening pattern of the samples. The bimetallic catalysts revealed higher activity and completely different selectivities than the monometallic Pt and Pd. Moreover, the 2MP/3MP ratio from trans-MECP and 2MP/nH ratio from cis-MECP increased as the surface Pt enrichment decreased. PdPt catalysts were cleaner than Pd or Pt, their activity higher and selectivity closer to random C–C rupture, due, very likely, to the presence of active Pd–Pt ensembles.

Rh catalysts supported on two graphite nanofiber structures (herring-bone – GNF-H and platelet – GNF-P) have been synthesized and characterized by XPS and HRTEM. Rh was partly oxidized after storage in air but reduced to Rh by H 2 treatments at 473 K. The graphitic character of GNF-P was closer to that of highly ordered pyrolytic graphite than that of GNF-H. H 2 treatment hardly affected the properties of the graphite component. HRTEM shows the appropriate graphite structures and Rh crystallites, mainly on the surface of GNF. The catalytic properties in ring opening of methylcyclopentane (MCP) were close to each other, Rh/GNF-P with more ordered graphite structure favoring “ring opening” to C 6 alkanes. The ring opening reaction was “selective”, producing more methylpentanes than hexane. This selectivity increased at higher H 2 pressures. As reported earlier, 2-methylpentane was the main source of 6 fragments. Considerably less fragments were produced on both Rh/GNF samples than on other Rh catalysts, due, likely, to more surface H on metallic active sites supplied from hydrogen stored by the GNF supports.

Absztrakt Szerzők egy rendkívül ritkán észlelt, a vena lienalison kialakult aneurysmáról számolnak be. A 34 éves nőbeteg felső hasi panaszok miatt került kivizsgálásra, amelyek hátterében CT-angiographia a vena lienalis aneurysmáját igazolta. A fusiformis, rendkívül vékony falú, 40 mm maximális átmérőjű saccularis tágulat a pancreas hátsó falán képezett benyomatot. A műtét során a v. lienalis és a lép megtartásával tangentialis resectiót végeztek. A beteg eseménytelenül gyógyult, és az 5. posztoperatív napon panaszmentesen távozott. 3 hónappal a műtét után panaszmentesen normál máj és pancreas laboratóriumi paraméterekkel került ellenőrző vizsgálatra.

Al (150 nm)/Ti (30 nm) contacts have been successively deposited onto p-type 6H–SiC wafers. The layer structure has been annealed at 900 °C for 4 min. The annealed contacts are Ohmic. The structure of the annealed contact layers was identified as a Ti 3 SiC 2 layer on SiC and covered by an Al 3 Ti layer. Both layers and phases are formed as a result of solid phase interaction between the metallic layers and SiC, and are epitaxial to the 6H–SiC. Ti 3 SiC 2 is suggested as a new contact material to p-type SiC, which promises high temperature stable contacts due to its excellent properties.

A viable colloid chemical preparation technique provided a series of low-loaded palladium-montmorillonite catalysts with cubooctahedral Pd particles ranging in size from 1.5 to 6.2 nm in mean diameter. These catalysts were used to test the structure sensitivity of the liquid-phase hydrogenation of styrene to ethylbenzene under mild conditions. An experimental correlation was sought between the specific rate of hydrogenation and the dispersion of the metal. The fractions of high-coordination terrace sites (face atoms) and low-coordination defect sites (edge and corner atoms) were calculated as a function of the crystallite size. The good correlation between the turnover frequencies and the defect site densities suggested that hydrogenation occurs on these defect sites and that terrace sites have only minimal catalytic activity or are inactive.