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Zinc is often regarded as an alternative to magnesium p-type dopants in gallium nitride. However, besides many theoretical predictions, at present, there are poor data on experimentally revealed p-type conductivity and evaluation of Zn activation energy by means of electrical transport measurements. In this paper, ammonothermal crystallization of bulk GaN:Zn monocrystals is reported. Despite a high doping level of Zn (up to 2 × 1020 cm−3), p-type conductivity with hole concentration as low as of 4 × 1015 cm−3 at room temperature and mobility about 3 cm2/V s was observed. A deep nature of the Zn acceptor was proved, as the ionization energy can exceed 260 meV. In addition, conduction in the impurity band appeared at temperatures as high as room temperature. [ABSTRACT FROM AUTHOR]

• Crystallization of GaN:Si,C was carried out to examine the role of C in n-type GaN crystals. • Intentional incorporation of high concentrations of Si and C is possible. • Raman spectroscopy shows low-frequency modes in co-doped crystals, suggesting SiC precipitates. • YL peak's position and intensity vary with dopant specifics, hinting at Si-C complexes or V Ga. In this work co-doping with silicon and carbon in gallium nitride grown by halide vapor phase epitaxy was performed. Native seeds of high structural quality with bowing radii of (0 0 0 1) crystallographic planes higher than 15 m and threading dislocation density on the order of 5 × 104 cm−3 were used. The crystallized material was examined in terms of structural, optical, and electrical properties. For this purpose different characterization methods: X-ray diffraction, Raman spectroscopy, low-temperature photoluminescence, and Hall measurements, were applied. The physical properties of samples doped only with silicon and co-doped with carbon were analyzed and compared. However, during the crystallization process, due to high amount of Si and C, clusters of silicon carbide were unintentionally formed. The formation of these SiC clusters had an impact on the properties of the GaN crystals that were being studied. The research provides an initial insight into the complex studies of co-doping gallium nitride crystals. The results of this paper give us groundwork for more in-depth exploration of this topic. [ABSTRACT FROM AUTHOR]

Background/Objectives. Cooccurrence of atopic dermatitis (AD) and psoriasis (PS) is not common. However, both diseases are still of interest because of their comprehensive and diverse mechanisms. This study aimed to present the clinical and immunological profiles of patients with concomitant AD and PS and compare them with those of patients with only one of the diseases. Methods. In this observational study, 38 children with concomitant AD and PS with a mean age of 6.5 ± 3.2 yrs were compared with 41 similar patients with AD only (5.3 ± 5.1 yrs) and 28 patients with PS only (6.4 ± 4.3 yrs). All patients underwent dermatological examinations, including determination of SCORAD and PASI scores. TNF-α, IFN-γ, IL-2, IL-4, IL-5, IL-6, IL-8, IL-12, IL-17, IL-18, IL-22, I:-33, and TARC/CCL17 were measured by ELISA according to the manufacturer's instructions. Results. Patients with concomitant AD and PS were frequently boys and overweight and had skin lesions equally distributed throughout the body. Children with concomitant AD and PS were more likely to report a family history of atopic disease than children with only AD or PS, and those with AD were more likely to report a family history of atopic disease than those with PS. Significant differences were observed in the concentration of IL-17 between patients with AD and PS and those with only AD or PS: 9.1 ± 3.7 pg/ml vs. 4.8 ± 2.9 pg/ml; and 9.1 ± 3.7 pg/ml vs. 5.2 ± 3.9 pg/ml, respectively (PD vs. AD, p = 0.01 ; PD vs. PS, p = 0.03). Conclusions. AD and PS can coexist. The role of T helper 17 cells may be more essential than believed. [ABSTRACT FROM AUTHOR]

Electrical properties of carbon-doped halide vapor phase epitaxy-GaN are presented and discussed. Crystals of the highest structural quality and with different carbon concentrations are investigated. Resistivity and Hall measurements as a function of temperature are analyzed in detail. It is found that the concentration of free holes systematically decreases with the increase of carbon concentration. Such behavior results from the fact that the compensation of the carbon acceptor level increases with the carbon concentration. It is accepted that carbon is amphoteric impurity in GaN, creating an acceptor as well as a donor state, which leads to self-compensation. The analysis of existing electron paramagnetic resonance results is extremely important. It enabled us to determine the compensation ratio as a function of carbon concentration. A combination of electron paramagnetic resonance, secondary ion mass spectrometry, and Hall data allowed us to conclude that the acceptor level (CN) exhibits rather significant temperature shift equal to 0.35 meV/K. [ABSTRACT FROM AUTHOR]

• Effectiveness of boron-bearing phases for the retardation of BYF cements. • Impact of boron on hydration kinetics. • Improvement of fresh and hardened mortar properties by retarder dosage optimisation. • Depletion of boron from solution. • Boron binding in hydrated cement matrix. This study investigates the effects of soluble boron-bearing compounds such as borax on the hydration and performance of belite ye'elimite ferrite cements (BYF). Boron effectively retards the hydration of BYF, independently of the type of borate used. The addition results in the higher initial spread, the slower decrease of the workability and increase of the compressive strength of mortar, when compared to the non-retarded systems. Tested boron-bearing phases dissolves fast, providing high initial concentration of boron in solution, depending on the initial boron content in mix. The concentration of boron decreases rapidly during the first 5 min of hydration, e.g. during the mortar mixing, independently whether the boron source was dissolved in the mixing water or added during the cement grinding. The boron concentration continues to steadily decrease afterwards. The dissolution of hydraulic reactive aluminate phases such as ye'elimite is slowed down or fully inhibited as long as boron concentration is relatively high. The initial rapid depletion of boron occurs simultaneously with the precipitation of an amorphous phase. Hence, we assume that boron is mainly adsorbed onto the surface of the amorphous phase. Contrary, the slower second period of the depletion of boron from solution can be more clearly linked to the formation of ettringite and monosulfate. [ABSTRACT FROM AUTHOR]

Abstract Recent progress in ammonothermal technology of bulk GaN growth in basic environment is presented and discussed in this paper. This method enables growth of two-inch in diameter crystals of outstanding structural properties, with radius of curvature above tens of meters and low threading dislocation density of the order of 5 × 104 cm−2. Crystals with different types of conductivity, n-type with free electron concentration up to 1019 cm−3, p-type with free hole concentration of 1016 cm−3, and semi-insulating with resistivity exceeding 1011 Ω cm, can be obtained. Ammonothermal GaN of various electrical properties is described in terms of point defects present in the material. Potential applications of high-quality GaN substrates are also briefly shown. [ABSTRACT FROM AUTHOR]

Four types of binders, based on the three different clinkers are investigated. These binders are of similar bulk chemical composition but contain different aluminate and silicate phases, which dissolve at different rates. The differences in reaction kinetics result in different phases assemblage at early ages. The phase assemblages tend to converge at later ages. Ettringite, AFm phases, C-S-H and strätlingite are the main hydrates. Their kinetics of formation and quantities depend on the dissolution rate of the anhydrous material. The differences in hydrates assemblage impact on the microstructures. Systems with ettringite or other crystalline hydrates as main hydration products at early ages, result in a coarser porosity. A refinement of the porosity is found in all the investigated samples with the ongoing formation of amorphous hydrates. Two mechanisms responsible for reduced hydration kinetics at later ages are identified: high Al concentration in the pore solution and dense microstructure. [ABSTRACT FROM AUTHOR]

Ferromagnetic behavior of GaN doped with Mn (Ga[sub 1-z]Mn[sub z]N) grown by the ammonothermal and chemical transport methods is discussed in terms of a second phase (ferromagnetic one) produced during the growth process. The reference manganese nitride samples grown by the same method as (Ga,Mn)N reveal room-temperature ferromagnetic behavior, depending on the growth details. Different Mn[sub x]N[sub y] phases are suggested to be responsible for ferromagnetic behavior of (Ga,Mn)N. [ABSTRACT FROM AUTHOR]

This paper reports measurements of the electrical resistances of bulk and milled amorphous lithium silicate (15Li 2 O-85SiO 2 ) under uniaxial load at 200 °C. With imposed load up to 700 MPa, the resistance of the melt-quenched glass increases from 1.56 to 1.95 MΩ cm. This change is reversible, namely after releasing the load the initial electrical resistance is recovered. Milled and compacted glass consists of the bulk and particle contacts resistances. Both of them increase when the external compression up to 200 MPa. For the bulk element, when compression is released, the initial resistance is recovered, whereas the resistance changes within the particles contacts are irreversible. [ABSTRACT FROM AUTHOR]

Results of gallium nitride crystallization by ammonothermal method are presented. GaN crystals grown earlier by a HVPE method on an ammonothermal GaN substrate and an MOCVD-GaN/sapphire template were used as seeds. Structural and optical properties of the obtained materials are studied and compared. Large radius of curvature (>100 m) and low dislocation density (7×10 4 cm −2 ) can be reproduced in the ammonothermal method using an HVPE-GaN seed grown before on ammonothermal GaN. This proves that the use of HVPE-GaN grown on ammonothermal seeds allows to reproduce high crystallinity in a subsequent ammonothermal growth. It also demonstrates that a much more effective multiplication process of high quality GaN can be launched using a combination of the ammonothermal and HVPE methods. [ABSTRACT FROM AUTHOR]

In answer to open questions (posed in [12]) we prove that an effect algebra has a Hilbert space effect-representation iff E possesses an ordering set of states. These are, up to isomorphism, all intervals and all their sub-effect algebras in the set of all positive linear operators on any Hilbert space. Nevertheless, there are effect algebras E, elements of which are linear operators in a Hilbert space, but E does not have such a representation. [Copyright &y& Elsevier]

Abstract: Polymer-derived carbon-rich SiOC ceramics were studied in view of its application as anode material for lithium ion batteries. The samples were prepared at 1100 and 1300°C by direct precursor pyrolysis or by a UV-radiation supported crosslinking applied before the thermal treatment. By means of various characterization techniques (Raman spectroscopy, X-ray diffraction, and elemental analysis) we found out that the UV-crosslinking procedure preceding the thermal treatment significantly influences the amount as well as the structural and electrochemical properties of the resulting carbon phase. The strong impact of those properties on the lithium insertion capacity and high current capability was analysed. The crosslinked sample prepared at 1100°C revealed a stable reversible capacity of more than 650mAhg−1 for lower currents and more than 80mAhg−1 when a charge/discharge current of 4000mAg−1 is used. The extended cycling with high current does not lead to sample damage and the initial capacity is recovered when lower currents are applied after the high current charging/discharging procedure. We attribute these excellent properties of the crosslinked sample prepared at 1100°C to the particular disorder of the carbon phase portioned in situ from the SiOC matrix under these conditions. [Copyright &y& Elsevier]

Abstract: Two polymer-derived SiOC ceramics with different amount of carbon were synthesized either as dense or porous SiOC powders. The dense materials were produced up to a maximum temperature of 1400°C and show a phase separated nanostructure consisting of SiO2-rich clusters, nanocrystalline SiC and nanocrystalline carbon phase. The corresponding porous materials were obtained by etching the silica phase of the dense SiOC with 20% HF solution. The electrochemical properties of the dense and porous SiOC ceramics in terms of lithium insertion/extraction were studied. Accordingly, the SiOC materials show a first lithium insertion capacity between 380 and 648mAhg−1 followed by significantly lower extraction capacities between 102 and 272mAhg−1. We consider the free carbon phase present in the ceramic as the major lithium intercalating agent. The porous samples show a stable electrochemical behavior up to 30 cycles while for the dense materials the efficiency drops to almost zero after 10 cycles. [Copyright &y& Elsevier]

In this paper we review the developments of producing non-polar (i.e. m-plane and a-plane) and semi-polar (i.e. (20.1)-plane) wafers by ammonothermal method. The growth method and polishing results are described. We succeeded in producing 26 mm × 26 mm non- and semi-polar wafers. These wafers possess outstanding structural and optical properties, with threading dislocation density of the order of 104 cm-3. Detailed studies of homoepitaxial layers, as well as AlGaN heterostructures are also presented, showing the potential of studied ammonothermal substrates in the fabrication of optoelectronic devices. [ABSTRACT FROM AUTHOR]

We show that the set of all positive linear operators densely defined in an infinite-dimensional complex Hilbert space can be equipped with partial sum of operators making it a generalized effect algebra. This sum coincides with the usual sum of two operators whenever it exists. Moreover, blocks of this generalized effect algebra are proper sub-generalized effect algebras. All intervals in this generalized effect algebra become effect algebras which are Archimedean, convex, interval effect algebras, for which the set of vector states is order determining. Further, these interval operator effect algebras possess faithful states. [ABSTRACT FROM AUTHOR]

Abstract: We report on a new composite material in view of its application as a negative electrode in lithium-ion batteries. A commercial preceramic polysilazane mixed with graphite in 1:1 weight ratio was transformed into a SiCN/graphite composite material through a pyrolytic polymer-to-ceramic conversion at three different temperatures, namely 950°C, 1100°C and 1300°C. By means of Raman spectroscopy we found successive ordering of carbon clusters into nano-crystalline graphitic regions with increasing pyrolysis temperature. The reversible capacity of about 350mAhg−1 was measured with constant current charging/discharging for the composite prepared at 1300°C. For comparison pure graphite and pure polysilazane-derived SiCN ceramic were examined as reference materials. During fast charging and discharging the composite material demonstrates enhanced capacity and stability. Charging and discharging in half an hour lead to about 200 and 10mAhg−1, for the composite annealed at 1300°C and pure graphite, respectively. A clear dependence between the final material capacity and pyrolysis temperature is found and discussed with respect to possible application in batteries, i.e. practical discharging potential limit. The best results in terms of capacity recovered under 1V and high rate capability were also obtained for samples synthesized at 1300°C. [Copyright &y& Elsevier]

Protection against BHV-5 disease induced by inactivated BHV-1 or BHV-5 based vaccines was analysed. Two groups of calves were subcutaneously immunized with an inactivated BHV-I or BHV-5 based vaccine. A third group was not vaccinated and used as control. In the post-vaccination period, we studied the humoral and cellular immune response resulting similar to both groups. The efficacy of the vaccines was tested alter intranasal challenge of the calves with a virulent Argentinean BHV-5 isolate (A-663). All control animals developed neurological signs associated with BHV-5 infection and high levels of virus shedding. Calves immunized with the BHV-1 and BHV-5 inactivated vaccines were protected against BHV-5 disease. Our study provides evidence that strongly support the existence of cross-protection between BHV-1 and BHV-5 in calves. Even though this has already been suggested by previous works, this is the first time an exhaustive study of the immune response is performed and typical clinical BHV-5 meningoencephalitis signs are reproduced in an experimental BHV-5 challenge trial. [ABSTRACT FROM AUTHOR]

Abstract: Polymer derived carbon-rich SiOC ceramics are prepared from polysiloxane precursors through a pyrolysis process at 1000°C using pure argon and argon/hydrogen mixture as pyrolysis atmosphere. The precursor is synthesized from a linear (Si–H)-containing polysiloxane cross-linked with divinylbenzene using hydrosilylation reaction in the presence of a platinum catalyst. Pyrolysis in Ar/H2 mixtures, compared to the treatment under pure Ar, results into a decrease of the concentration of C dangling bonds as revealed by electron spin resonance (ESR) measurements. The amount of free carbon phase is 10wt.% lower in the sample pyrolysed in a Ar/H2 mixture, while the ratio of hydrogen to free carbon remains constant for both, in Ar and in Ar/H2 pyrolysed samples. The sample prepared under Ar/H2 mixture shows an excellent cycling stability with an increase in the specific capacity of about 150mAhg−1 compared to its analogues pyrolysed in pure argon atmosphere. [Copyright &y& Elsevier]

In this work, a novel type of supplementary cementitious material (SCM), produced by the calcination of aluminosilicate such as clays and micas in the presence of dolomite, is investigated. The thermal activation was assessed at different calcination temperatures. The activity of the produced SCM was tested in combination with Portland cement in paste and mortar. The compressive strength results demonstrate that the novel SCM out-performs all tested state of the art references. The cause for the improved reactivity is associated with the formation of poorly crystalline, reactive calcium and magnesium-rich phases such as free lime, periclase, melilite, dicalcium silicate, calcium aluminates and ferrites during the calcination. The hydration study of the different composite cements demonstrates that the presence of the novel SCM results in a higher quantity of portlandite formed, the stabilisation of ettringite over monosulfate and the formation of strätlingite together with hemicarboaluminate. [ABSTRACT FROM AUTHOR]

The magnetization of Ga[sub 1-x]Mn[sub x]N (x<0.1) crystals was measured as a function of the magnetic field and temperature. Paramagnetic behavior typical of spin S=5/2 expected for Mn[sup 2+] (d[sup 5]) magnetic centers was observed in the temperature range of 2 K

Ammonothermal GaN samples with the concentration of free electrons of 1018 and 1019 cm−3 were annealed in a wide range of temperatures (Tann = 300–1400 °C) under atmospheric N2 pressure and under ultra-high N2 pressure conditions to avoid the GaN decomposition. Photoluminescence (PL) studies reveal the YL2 band with a maximum at 2.3 eV before annealing and two new PL bands after annealing at Tann > 600 °C: the OL3 band with a maximum at 2.1 eV and the RL4 band with a maximum at 1.6–1.7 eV. The ammonothermal GaN samples have high concentrations of complexes containing gallium vacancy (VGa), hydrogen, and oxygen. The first-principles calculations suggest that the VGa-3Hi complex is the origin of the YL2 band, while the VGa-3ON complex is responsible for the RL4 band. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) from GaN substrates fabricated by the ammonothermal growth method was studied in a wide range of temperatures and excitation intensities, both with steady-state and time-resolved PL techniques. Three defect-related PL bands were detected: the ultraviolet luminescence band with the zero-phonon line at 3.27 eV, the Zn-related BL1 band with a maximum at 2.9 eV, and the yellow luminescence band (labeled YL2) with a maximum at 2.3 eV. The YL2 band belongs to an unknown defect and is different from the CN-related YL1 band. Its maximum blueshifts by 0.06 eV with increasing excitation intensity and redshifts by more than 0.1 eV with a time delay after a laser pulse. The YL2 band is preliminarily attributed to a defect complex containing the gallium vacancy. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Treatment with azathioprine and cyclic methylprednisolone has little or no effect on bioactivity in anti-interferon beta antibody-positive patients with multiple sclerosis," by M. Ravnborg and colleagues.

In this work, we present an easy and environmentally friendly approach to stabilize nanostructured, porous crystalline (Si tc ) and amorphous (Si sa ) silicon synthesized via magnesiothermic reduction. As matrix, fructose-derived carbon, polymer-derived SiOC ceramic or both, carbon and SiOC, are used. By means of X-ray diffraction and Raman spectroscopy it is found that the crystallinity of Si tc as well as the amorphous character of Si sa is preserved in the final composites. Embedding of crystalline silicon into carbon leads to high initial capacities of ~ 600–650 mAh·g − 1 , but only the matrix consisting of carbon and SiOC results in a stable cycling behaviour over 50 cycles with a final capacity of 575 mAh·g − 1 . All composites derived from amorphous Si sa show a stable cycling behaviour; the highest, stable capacity of ~ 500 mAh·g − 1 is observed when silicon is covered with carbon and SiOC. [ABSTRACT FROM AUTHOR]

Bovine herpes virus type 5 (BHV-5) is the causal agent of fatal meningoencephalitis in calves. Frequent outbreaks have been reported in Argentina, Brazil, Australia, United States and sporadically in other countries. Because of the close genetic and antigenic relationship between BHV-1 and BHV-5, prior vaccination against BHV-1 may protect against encephalitis caused by BHV-5. In this work we evaluate the efficacy of inactivated vaccines formulated with BHV-1 or BHV-5 for protection against BHV-5 virus infection. For this proposal we immunized 2 groups of 6 months old calves, 4 animals with BHV-1 wild type (wt) vaccine and 5 animals with BHV-5 vaccine, both inactivated and through subcutaneous route. One group of 7 animals was used as unvaccinated controls. Twenty-one days post vaccination (dpv) the animals were revaccinated and 41 dpv the three groups were intranasally challenged with BHV-5 (663 strain, Argentinean isolated, 107DICT50/ml). Clinical observations and rectal temperature were recorded daily for 24 days post challenge (dpch). Nasal swabs were taken from each animal to monitor virus excretion after virus inoculation. Control animals developed severe sero-mucous nasal discharge, conjunctivitis and neurological signs after challenge. Virus excretion was detected between days 2 and 15 pch and peak on day 9 pch (4.23 DICT50/ml). Both groups of vaccinated animals were protected against challenge since 5 of 9 calves did not present virus shedding in the studied period and 4 of 9 calves excreted lower virus titers compared with the mock-vaccinated animals (2.33-3.33 DICT50/ml). Three of nine animals presented slight neurological signs. No temperature differences were observed in any animal after virus inoculation. Our study suggests a cross protection between BHV-1 and BHV-5 since animals vaccinated against BHV-1 were protected from BHV-5 infection, although it would be necessary a confirmation of these results with a large number of animals. [ABSTRACT FROM AUTHOR]

Porous carbon-rich SiOC ceramic aerogels have been synthesized from a linear polysiloxane cross-linked with divinylbenzene (DVB) via hydrosilylation reaction in presence of a Pt catalyst and acetone as a solvent. The obtained wet gels are aged in solvent followed by drying under supercritical conditions using liquid carbon dioxide. The resulting pre-ceramic aerogels are subjected to pyrolysis at 1000 °C under controlled argon atmosphere to form the desired SiOC aerogel. The synthesized SiOC ceramics contain 43 wt% of free carbon, which is segregated within amorphous SiOC matrix. The high BET surface area up to 230 m 2 g −1 of preceramic aerogels is only slightly diminished to 180 m 2 g −1 after pyrolysis at 1000 °C. The electrochemical characterization reveals a high specific capacity of more than 600 mAh g −1 at a charging rate of C (360 mA g −1 ) along with a good cycling stability. At a rate of 10C (3600 mA g −1 ) the specific capacities as high as 200 mAh g −1 are recovered. The excellent properties of the materials are discussed with respect to their structural features. The porous nature of the carbon rich ceramics allows for fast ionic transport and helps to accommodate the structural changes which in turn allow a stable performance during repeated lithiation/delithiation. [ABSTRACT FROM AUTHOR]

Polymer derived silicon oxycarbide (SiOC) ceramics are investigated as potential anodes for lithium ion batteries. Different SiOC ceramics are prepared by pyrolysis (1000°C and 1400°C under controlled argon atmosphere) of polysiloxanes ceramic precursors. Preceramic polymers are synthesized using the sol–gel method. Phenyltriethoxysilane (PhTES) and methyltriethoxysilane (MTES) have been used as starting precursors and mixed with different ratios in order to tailor the chemical composition and the structure of the final product. The obtained SiOC ceramics are amorphous with various content of free carbon phase (from approx. 25 to 40wt.%). The presence of disordered carbons in the ceramic structure is confirmed by the appearance of a well pronounced D band at 1330cm−1 in the Raman spectra. Additionally, 29Si MAS-NMR spectra show the presence, in the structure of the materials pyrolysed at 1000°C, of mixed bond tetrahedra such as: Si O3C, Si O2C2, Si OC3 and Si O4 units. Pyrolysis at an elevated temperature (1400°C) promotes the phase separation into oxygen rich (SiO4) and carbon rich (SiC4) units with consumption of mixed bonds. Carbon rich SiOC samples exhibit significant reversible capacity and enhanced cycling stability (up to 600mAhg−1 measured at a slow current rate of C/20 after 140cycles of continuous charging–discharging with increasing current density). However, the high irreversible capacity of the first few cycles remains an issue to be solved. [ABSTRACT FROM AUTHOR]

For any dense linear subspace D of a complex Hilbert space we introduce and study a D-weak operator topology τ D on the set of all positive linear operators with domain D. For instance, we show that every is τ D -limit of a nondecreasing sequence of bounded operators from. Let τ w denote the weak operator topology on the set of all bounded linear operators and let denote the set of all positive bounded linear operators. For the corresponding relative topologies we show that and the converse inclusion need not hold. Some topological properties of the operator generalized effect algebra and its intervals (all of which are effect algebras) are also studied. [Copyright &y& Elsevier]

Ultrathin (8 and 16 Å) epitaxial Co films were grown on Au(0 0 1)-hex substrates. The films were characterized in situ by LEED, STM and the directional Auger electron spectroscopy (DAES) and ex situ by magnetooptic Kerr effect. From LEED and DAES data it was found that a distorted bcc-Co phase can be stabilized on Au(0 0 1)-hex at least up to 10 ML. The easy axis of magnetization for the bcc-Co films coated with Au lies in-plane along a 〈1 0 0〉 direction. [Copyright &y& Elsevier]

We studied the structural and optical properties of state-of-the-art non-polar bulk GaN grown by the ammonothermal method. The investigated samples have an extremely low dislocation density (DD) of less than 5 × 104 cm-2, which results in very narrow high-resolution x-ray rocking curves. The a and c lattice parameters of these stress-free GaN samples were precisely determined by using an x-ray diffraction technique based on the modified Bond method. The obtained values are compared to the lattice parameters of free-standing GaN from different methods and sources. The observed differences are discussed in terms of free-electron concentrations, point defects, and DD. Micro Raman spectroscopy revealed a very narrow phonon linewidth and negligible built-in strain in accordance with the high-resolution x-ray diffraction data. The optical transitions were investigated by cathodoluminescence measurements. The analysis of the experimental data clearly demonstrates the excellent crystalline perfection of ammonothermal GaN material and its potential for fabrication of non-polar substrates for homoepitaxial growth of GaN based device structures. [ABSTRACT FROM AUTHOR]

We report on the in-plane magnetic anisotropy and temperature dependence of the exchange bias in epitaxial CoO(111)/Fe(110) bilayers. The Fe thickness induced in-plane spin reorientation transition and the existence of the exchange bias below the blocking temperature ≈ 27 K is documented in CoO(111)/Fe(110) system. For dFe = 80 Å, we find that the hysteresis loop shift-field, HEB, reaches the value ≈ 250 Oe at 184 K. A true interplay between antiferromagnetic CoO and ferromagnetic Fe layers is described. [ABSTRACT FROM AUTHOR]

Within this work, monodisperse porous silicon nanospheres have been derived from monodisperse silica nanospheres via two different magnesiothermic reduction routes, namely (i) magnesiothermic reduction using a two-chamber set-up, and (ii) magnesiothermic reduction using NaCl as heat scavenger. Both methods allow a size- and shape-preserving preparation of mesoporous silicon. Crystalline silicon with a particle size of 56 nm and a specific surface area of 198 m 2 g − 1 and amorphous silicon with a particle size of 35 nm and a specific surface area of 623 m 2 g − 1 are synthesized using the two chamber and salt assisted routes, respectively. TEM micrographs confirm enhanced porous character of silicon from NaCl assisted route. An unstable electrochemical performance of the crystalline silicon is found, whereas the amorphous Si presents a stable electrochemical behavior. [ABSTRACT FROM AUTHOR]

Study on the sources of stress in HVPE-GaN layer crystallized on 1-in. ammonothermally grown GaN seed is presented in this paper. Characterization by means of X-ray diffraction and transmission electron microscopy is performed. HVPE-GaN samples of high quality and those with visible quality deterioration are investigated on c-plane and m-plane cross-sections. Special attention is paid to HVPE material growing in semi-polar and non-polar directions on the edges of the seed and the growing layer. It is shown that this material generates significant stress leading to a structural deterioration of HVPE-GaN growing in the c -direction. [ABSTRACT FROM AUTHOR]

Introduction: Interferon-β (IFNβ) is the first-line treatment for relapsing-remitting multiple sclerosis. Myxovirus resistance protein A (MxA) is considered to be an IFNß bioactivity marker. Responsiveness to the IFNß treatment may be reduced by neutralizing antibodies (NAbs). Material and methods: We investigated the presence of NAbs and mRNA MxA expression in a group of patients who had started IFNß treatment. mRNA MxA was measured with real-time PCR every three months. MxA induction was performed in patients in whom continuous decline was detected. NAbs were determined using the cytopathic effect method every six months. Patients were regularly observed clinically and with MRI. Results: 119 patients were included, 99 completed the observation period of 24 months. NAbs positivity was observed in 17 patients, mostly in month 12 and 18. NAbs positivity was permanent in ten patients (10%). Nabs titre of 20-100 TRU/ml was associated with a decline in MxA levels under the cut-off in 85% of cases, and in all patients when Nabs titre exceeded 100 TRU/ml. Permanent MxA decline was seen in 19 patients - in all 10 patients with permanent NAbs positivity, in three patients with transitional NAbs positivity and in six patients without NAbs. The MxA induction was insuffi cient in all permanent NAbs positive patients and in two patients with isolated MxA decrease and without NAbs. MxA decrease preceded NAbs positivity in 40% of cases. Conclusion: MxA becomes the main laboratory marker of IFNβ efficacy as it can indicate patients at risk of IFNβ efficacy loss, even in situations when patients produce NAbs. MxA induction is necessary to verify IFNβ efficacy. [ABSTRACT FROM AUTHOR]

A letter to the editor is response to an article the comparison of SAPs 2 and SAPS 3 in anaesthesiology, published in a previous issue of the journal is presented.

Purpose The aim of the study was to quantify low and high order Zernike aberrations in children and youths as well as to investigate influence of fogging and cycloplegia on the refraction and aberrations measurement. Methods KR‐1W Topcon aberrometer was used to measure aberrations in refractometer and aberrometer mode. Children were examined three times. First examination in whole group was performed after fogging stimulus used once ‐ in first of three continuous measurements, second after fogging stimulus performed for each measurement and third after pharmacological cycloplegia with 1% Tropicamid. Second and third measurements were performed in selected group of children. Totally 556 schoolchildren and 74 young sportsmen aged from 6‐to‐18 years were investigated. Average age was 13.87, SD 2.29 in large group and 11.33 years, SD 2.7 in smaller group. Results We found significant differences in spherical refraction measured after pharmacological cycloplegia compared to that after fogging. Refraction after cycloplegia was more hyperopic. There were higher differences in high hyperopic children. There were no differences between fogging and cycloplegic measurements in myopes higher then ‐2.00 D.. Aberrometry has given more myopic results then refractometry. Cylinder values were almost the same. Keratometer readings were the same in all measurements conditions. We found similar levels of high order aberrations in myopic, emmetropic and hyperopic children. There was no noticeable symmetry in high order aberrations between right and left eye. Conclusion Both methods of low order aberrations measurement are similar. Optical parameters of cornea do not depend on the cycloplegic status. Low order Zernike aberrations strictly correspond to the refraction error. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study was to determine the quality of vision, refraction, and aberrations in a group of children and adolescens in selected schools of the city Siemianowice Slaskie (Southern Poland). Methods Visual quality was evaluated as visual acuity measured with two methods: OPTEC® Vision Tester and FrACT computer programme as well as contrast threshold for 30 arc min size optotypes. Refraction was determined with Topcon KR‐1W aberrometer which enables its measuring with "refractor" method or its calculation from low‐order Zernike aberrations. Results Totally 556 children aged from 8‐to‐17 years (average age 13.87, standard deviation 2.29), were investigated. Visual acuity varied within great range, but average value remained almost constant on the level slightly better that V = 5/5 (ca. ‐0.06 logMAR) in the group whithout vision problems. In the group of children with detected refraction errors (wearing glasses) average visual acuity decreased by 0.1 log units in every 5 years.There was high correlation between contrast threshold and visual acuity. We noticed an increase in the average spherical error in the amount of –0.5 D in the time interval of about 5 years. Conclusion Both methods testing visual acuity investigated by the authors are comparable and may be used as screening for children. The FrACT test for screening visual acuity and contrast is a method that would be appropriate to be used in children and teenagers in view of its similarity to computer games and its short time duration. The distribution of visual defects is comparable to that found in other screening tests on the Polish and European populations. [ABSTRACT FROM AUTHOR]

The nanocrystallization kinetics of Fe9oZr7B3 is investigated by in situ nuclear forward scattering of synchrotron radiation upon isothermal annealing. The nucleation and growth processes are accessed separately for the nanograins, their interfaces, and the residual amorphous matrix by monitoring the time evolution of the corresponding hyperfine parameters. This approach discloses the structural transformations taking place in this class of technologically important materials. [ABSTRACT FROM AUTHOR]

Series of Fe3O4/MgO(001) and Fe3O4/Fe/MgO(001) films (single- and bi-layer films, respectively) with a total layer thickness in the range of 20÷150 nm were investigated by the Rutherford backscattering spectrometry (2 MeV He+ ion beam), by the Rutherford backscattering spectrometry channeling experiments (1.5 MeV He+ ion beam). Depending on the layer thickness of each layer and the film geometry, a single Fe peak and/or a double-anomaly feature was revealed in the Rutherford backscattering spectra. For all films no magnesium presence in the surface layer was observed. For both single- and bi-layer films with a total layer thickness less than 60 nm only one minimum was observed in the channeling curves, while a double minimum was revealed for the bi-layer films with a larger thickness. X-ray reflectometry measurements have revealed that the film density is the same as that of the bulk one. [ABSTRACT FROM AUTHOR]

No abstract available Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: In this work results of extensive characterization of homoepitaxial layers grown on truly bulk ammonothermal gallium nitride (GaN) substrates are presented. The 2-μm-thick layers were deposited using metalorganic chemical vapor deposition. The photoluminescence (PL) and reflectance results show very intensive, perfectly resolved excitonic structure in range of band-edge emission of gallium nitride. This structure consists of both lines related to free excitons emission and very narrow lines (full-width at half-maximum (FWHM) value of the order of 0.3meV) related with excitons bound to neutral acceptor and different neutral donors. In high excitation condition the biexciton emission was observed. The luminescence is uniform in the whole sample surface range. High PL homogeneity corresponds with structural and microscopic measurements performed on these layers. It proves that ammonothermal GaN substrates with perfect crystalline properties enable to grow excellent quality, strain-free homoepitaxial layers. [Copyright &y& Elsevier]