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Lead chalcogenides have exceptional thermoelectric properties and intriguing anharmonic lattice dynamics underlying their low thermal conductivities. An ideal material for thermoelectric efficiency is the phonon glass-electron crystal, which drives research on strategies to scatter or localize phonons while minimally disrupting electronic-transport. Anharmonicity can potentially do both, even in perfect crystals, and simulations suggest that PbSe is anharmonic enough to support intrinsic localized modes that halt transport. Here, we experimentally observe high-temperature localization in PbSe using neutron scattering but find that localization is not limited to isolated modes - zero group velocity develops for a significant section of the transverse optic phonon on heating above a transition in the anharmonic dynamics. Arrest of the optic phonon propagation coincides with unusual sharpening of the longitudinal acoustic mode due to a loss of phase space for scattering. Our study shows how nonlinear physics beyond conventional anharmonic perturbations can fundamentally alter vibrational transport properties.

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Vertically aligned CNT carpets combined with inorganic semiconductors are expected good prospect in practical applications, especially in photocatalysis. If these devices are in production, a fast and non-invasive characterization method will be required. Ellipsometry is widely used in industry as an in-line monitoring tool, so in this study the applicability of ellipsometry for characterizing CNT carpets is investigated. It is shown that ellipsometric evaluation can provide information about the density and the optical properties of the nanotubes; however, the properties of the individual nanotubes (diameter, wall number) can not be taken into account during ellipsometric modeling. To overcome these limitations, numerical simulations are also presented.

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Controlling the thermal energy of lattice vibrations separately from electrons is vital to many applications including electronic devices and thermoelectric energy conversion. To remove heat without shorting electrical connections, heat must be carried in the lattice of electrical insulators. Phonons are limited to the speed of sound, which, compared to the speed of electronic processes, puts a fundamental constraint on thermal management. Here we report a supersonic channel for the propagation of lattice energy in the technologically promising piezoelectric mineral fresnoite (Ba2TiSi2O8) using neutron scattering. Lattice energy propagates 2.8-4.3 times the speed of sound in the form of phasons, which are caused by an incommensurate modulation in the flexible framework structure of fresnoite. The phasons enhance the thermal conductivity by 20% at room temperature and carry lattice-energy signals at speeds beyond the limits of phonons.

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How boundaries surrounding recrystallization grains migrate through the 3D network of dislocation boundaries in deformed crystalline materials is unknown and critical for the resulting recrystallized crystalline materials. Using X-ray Laue diffraction microscopy, we show for the first time the migration pattern of a typical recrystallization boundary through a well-characterized deformation matrix. The data provide a unique possibility to investigate effects of both boundary misorientation and plane normal on the migration, information which cannot be accessed with any other techniques. The results show that neither of these two parameters can explain the observed migration behavior. Instead we suggest that the subdivision of the deformed microstructure ahead of the boundary plays the dominant role. The present experimental observations challenge the assumptions of existing recrystallization theories, and set the stage for determination of mobilities of recrystallization boundaries.

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Relaxor ferroelectrics exemplify a class of functional materials where interplay between disorder and phase instability results in inhomogeneous nanoregions. Although known for about 30 years, there is no definitive explanation for polar nanoregions (PNRs). Here we show that ferroelectric phonon localization drives PNRs in relaxor ferroelectric PMN-30%PT using neutron scattering. At the frequency of a preexisting resonance mode, nanoregions of standing ferroelectric phonons develop with a coherence length equal to one wavelength and the PNR size. Anderson localization of ferroelectric phonons by resonance modes explains our observations and, with nonlinear slowing, the PNRs and relaxor properties. Phonon localization at additional resonances near the zone edges explains competing antiferroelectric distortions known to occur at the zone edges. Our results indicate the size and shape of PNRs that are not dictated by complex structural details, as commonly assumed, but by phonon resonance wave vectors. This discovery could guide the design of next generation relaxor ferroelectrics.

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The ability to synthesize VO2 in the form of single-crystalline nanobeams and nano- and microcrystals uncovered a number of previously unknown aspects of the metal-insulator transition (MIT) in this oxide. In particular, several reports demonstrated that the MIT can proceed through competition between two monoclinic (insulating) phases M1 and M2 and the tetragonal (metallic) R phase under influence of strain. The nature of such phase behavior has been not identified. Here we show that the competition between M1 and M2 phases is purely lattice-symmetry-driven. Within the framework of the Ginzburg-Landau formalism, both M phases correspond to different directions of the same four-component structural order parameter, and as a consequence, the M2 phase can appear under a small perturbation of the M1 structure such as doping or stress. We analyze the strain-controlled phase diagram of VO2 in the vicinity of the R-M2-M1 triple point using the Ginzburg-Landau formalism and identify and experimentally verify the pathways for strain-control of the transition. These insights open the door toward more systematic approaches to synthesis of VO2 nanostructures in desired phase states and to use of external fields in the control of the VO2 phase states. Additionally, we report observation of the triclinic T phase at the heterophase domain boundaries in strained quasi-two-dimensional VO2 nanoplatelets, and theoretically predict phases that have not been previously observed.

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This paper addresses the formation of nanostructured gallium nitride nucleation (NL) or initial layer (IL), which is necessary to obtain a smooth surface morphology and reduce defects in h-GaN layers for light-emitting diodes and lasers. From detailed X-ray and HR-TEM studies, researchers determined that this layer consists of nanostructured grains with average grain size of 25 nm, which are separated by small-angle grain boundaries (with misorientation approximately 1 degrees), known as subgrain boundaries. Thus NL is considered to be single-crystal layer with mosaicity of about 1 degrees. These nc grains are mostly faulted cubic GaN (c-GaN) and a small fraction of unfaulted c-GaN. This unfaulted Zinc-blende c-GaN, which is considered a nonequilibrium phase, often appears as embedded or occluded within the faulted c-GaN. The NL layer contained in-plane tensile strain, presumably arising from defects due to island coalescence during Volmer-Weber growth. The 10L X-ray scans showed c-GaN fraction to be over 63% and the rest h-GaN. The NL layer grows epitaxially with the (0001) sapphire substrate by domain matching epitaxy, and this epitaxial relationship is remarkably maintained when c-GaN converts into h-GaN during high-temperature growth.

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Polychromatic X-ray microdiffraction is an emerging tool for studying mesoscale structure and dynamics. Crystalline phase, orientation (texture), elastic and plastic strain can be nondestructively mapped in three dimensions with good spatial and angular resolution. Local crystallographic orientation can be determined to approximately 0.01 degree and elastic strain tensor elements can be measured with a resolution of approximately 10(-4) or better. Complete strain tensor information can be obtained by augmenting polychromatic microdiffraction with a monochromatic measurement of one Laue-reflection energy. With differential-aperture depth profiling, volumes tens to hundreds of micrometers below the surface are accessible so that three-dimensional distributions of crystalline morphology including grain boundaries, triple points, second phases and inclusions can all be mapped. Volume elements below 0.25 microm3 are routinely resolved so that the grain boundary structure of most materials can be characterized. Here the theory, instrumentation and application of polychromatic microdiffraction are described.

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A recently developed differential-aperture X-ray microscopy (DAXM) technique provides local structure and crystallographic orientation with submicron spatial resolution in three-dimensions; it further provides angular precision of approximately 0.01 degrees and local elastic strain with an accuracy of approximately 1.0 x 10(-4) using microbeams from high brilliance third generation synchrotron X-ray sources. DAXM is a powerful tool for inter- and intra-granular studies of lattice distortions and lattice rotations on mesoscopic length scales of tenths of microns to hundreds of microns that are largely above the range of traditional electron microscopy probes. Nondestructive, point-to-point, spatially resolved measurements of local lattice orientations in bulk materials provide direct information on geometrically necessary dislocation density distributions through measurements of the lattice curvature in plastically deformed materials. This paper reviews the DAXM measurement technique and discusses recent demonstrations of DAXM capabilities for measurements of microtexture, local elastic strain, and plastic deformation microstructure.

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Advanced materials and processing techniques are based largely on the generation and control of non-homogeneous microstructures, such as precipitates and grain boundaries. X-ray tomography can provide three-dimensional density and chemical distributions of such structures with submicrometre resolution; structural methods exist that give submicrometre resolution in two dimensions; and techniques are available for obtaining grain-centroid positions and grain-average strains in three dimensions. But non-destructive point-to-point three-dimensional structural probes have not hitherto been available for investigations at the critical mesoscopic length scales (tenths to hundreds of micrometres). As a result, investigations of three-dimensional mesoscale phenomena--such as grain growth, deformation, crumpling and strain-gradient effects--rely increasingly on computation and modelling without direct experimental input. Here we describe a three-dimensional X-ray microscopy technique that uses polychromatic synchrotron X-ray microbeams to probe local crystal structure, orientation and strain tensors with submicrometre spatial resolution. We demonstrate the utility of this approach with micrometre-resolution three-dimensional measurements of grain orientations and sizes in polycrystalline aluminium, and with micrometre depth-resolved measurements of elastic strain tensors in cylindrically bent silicon. This technique is applicable to single-crystal, polycrystalline, composite and functionally graded materials.

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The increasing role of vaccination in prevention of infectious diseases, the newly introduced vaccines and immunization systems are dealt with. Some recent and future alterations in the field of the basic vaccination system are discussed. Special emphasis is laid on the new vaccines and immunization methods which can be used with good results in preventing some important infectious diseases at home, as well as staying in developing countries, too.

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According to international references the publication ascertains the etiologic role of neurotoxin producing Clostridial spp., other than C. botulinum in Infant botulism. Authors report on the first Hungarian case of Infant botulism. The organism isolated -- C. barati -- is responsible only for a small proportion of published cases. Authors point out the conjunction of Infantile botulism and crib death.

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Pulsed-laser deposition was used to synthesize artificially layered high-temperature superconductors. Thin-film compounds were formed when the constraint of epitaxy was used to stabilize SrCuO(2)-BaCuO(2) superlattices in the infinite layer structure. Using this approach, two new structural families, Ba(2)Srn-1,Cun+1 O2n+2+delta and Ba(4)Srn-1 Cun+3O2n+6+delta have been synthesized; these families superconduct at temperatures as high as 70 kelvin.

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Children who had previously received Morbilli-(Mumps) Rubella (MMR) vaccine developed parotid swelling which was diagnosed as acute parotitis 7 days to 2 years following inoculation. Blood samples from each of the patients were tested for the following virological parameters: Mumps-virus, Parainfluenza-viruses (PIV) type 1., 2., 3., Respiratory Syncytial Virus (RSV), Epstein Barr Virus Capsid Antigen (EBVCA) IgM, IgA, IgG immunofluorescent test (IFT) and EBVCA IgM, IgG ELISA (HUMAN); Epstein Barr Virus Early Antigen (EBV EA) IgG IFT; Adenovirus, Influenza A, B Complement Fixation (CF) test. Some of the sera were examined for CMV IgM, IgG ELISA (Organon Teknika) and Human Parvovirus B19 IgM, IgG recombinant ELISA (Bender) too. Nine cases were interpreted as a clinical reaction of mumps vaccination. Beside the clinical reaction of mumps vaccination. Beside the clinical reaction of mumps vaccination, the etiological role of PIV-1, PIV-2, PIV-3 and PIV-1,2 was confirmed in four, three, one and one patients, respectively. The alonely etiological agent was the PIV-2 in four and PIV-2 and Epstein-Barr virus together were in one patients, respectively. The etiology was unknown in one patient. The results show the importance both of the broad spectrum precise serologic studies and of the skillful interpretation in the exact diagnosis of the acute parotitis to identify parotitis either as a consequence of the mumps vaccine or vaccine failure. The correct diagnosis of acute parotitis can influence the booster mumps vaccination practice too.

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Intestinal infections of still high importance from the hygienic-epidemiological aspects and the recent results obtained in this field have been surveyed. Recently recognized enteric pathogens (campylobacter, Yersinia, rotavirus, Clostridium difficile, etc.) as well as the newest data on the pathomechanism of intestinal infections have been discussed. These data not only have increased our knowledge of the pathology but also resulted in basic, favourable changes in therapy. Detailed information is given on specific preventive measures, currently used vaccines and the research activities in this field. Detailed description of the therapeutic methods, salt and fluid substitution and up-to-date aspects of antibiotic treatment have been given as guidelines for the everyday medical practice.

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