Condensed Matter Physics

EuCARD-2 is a project partly supported by FP7-European Commission aiming at exploring accelerator magnet technology for 20 T dipole operating field. The EuCARD-2 collaboration is liaising with similar programs for high field magnets in the USA and Japan. EuCARD-2 focuses, through the workpackage 10 "Future magnets," on the development of a 10 kA-class superconducting, high current density cable suitable for accelerator magnets, for a 5 T stand-alone dipole of 40 mm bore and about 1 m length. After standalone testing, the magnet will possibly be inserted in a large bore background dipole, to be tested at a peak field up to 18 T. This paper starts by reporting on a few of the highlight simulations that demonstrate the progress made in predicting: dynamic current distribution and influence on field quality, complex quench propagation between tapes, and minimum quench energy in the multitape cable. The multiphysics output importantly helps predicting quench signals and guides the development of the novel early detection systems. Knowing current position within individual tapes of each cable we present stress distribution throughout the coils. We report on the development of the mechanical component and assembly processes selected for Feather-M2 the 5 T EuCARD2 magnet. We describe the CERN variable temperature flowing helium cold gas test system. We describe the parallel integration of the FPGA early quench detection system, using pickup

A previously synthesized hyperbranched poly(butylene adipate) (HPBA) polymer was compared with a commercial dendritic polyol (HPOH) as a toughening agent for a commercial one-part epoxy resin. Both modifiers were added in weight percentages of 1, 3, 5, and 10%. The modified epoxies were characterized using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), melt rheological tests, and linear elastic fracture mechanics. Blend morphology and matrix-modifier interactions were evaluated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. The toughness-improvement effect was achieved without substantial impairment of thermomechanical properties or degradation of the thermal stability of the epoxy resin. A meaningful decrease in viscosity was achieved with both modifiers, contributing to an easier infusion processability. No evidence of new chemical linking was found although phase separation was observed by SEM, leading to the conclusion that only interfacial linkage occurs between modifiers and epoxy chains. SEM analysis also clearly shows the fracture mode changing from brittle to ductile by addition of modifiers, which was more evident for blends of HPBA.

The local surface chemistry of a low-Ni austenitic stainless steel AISI type 304 used for tensile testing in hydrogen atmosphere is characterized by secondary ion mass spectrometry (SIMS). A chemical map on cylindrical austenitic stainless steel samples can be obtained even after a tensile test. In an effort to obtain the proper chemical element distribution on the samples, the influence of contamination and sample orientation is discussed. An iron oxide on top of a chromium oxide layer is present and Si segregation at grain boundaries is detected. Oxides are judged to reduce the initial hydrogen attack but to be of minor importance for crack propagation during the embrittlement process.

The influence of some impurity ions on the increase/decrease in the resistance against irradiation of metal oxides with X-rays and electrons (low-dense excitation) or $2 GeV Au 198 and U 238 ions providing a superhigh density of electronic excitations along cylindrical tracks (LET > 30 keV nm À1 ) has been investigated for fcc MgO single crystals with close ion masses or Lu 3 Al 5 O 12 and Gd 2 SiO 5 with large unit cells and heavy cations. The radiation effects have been studied using the methods of low-temperature vacuum ultraviolet spectroscopy (up to 40 eV), cathodoluminescence and thermoactivation spectroscopy. The step-by-step annealing of the radiation-induced absorption, scattering, and luminescence has been performed at the heating of irradiated crystals up to $70% of a melting point. Possible experimental manifestations of the temperature-stable nanosize 3D defects created, according to theoretical predictions, via rearrangement of many host ions at the collapse of discrete solitons (breathers) are detected in Lu 3 Al 5 O 12 and Gd 2 SiO 5 crystals irradiated with swift heavy ions (fluence of 10 12 ions cm À2 ).

Fermilab is developing and investigating different high-field magnet designs for present and future accelerators. The magnet R&D program was focused on the 10-12 T accelerator magnets based on Nb 3 Sn superconductor and explored both basic magnet technologies for brittle superconductors-wind-and-react and react-and-wind. Magnet design studies in support of LHC upgrades and VLHC are being performed. A series of 1-m long single-bore models of cos-theta Nb 3 Sn dipoles based on wind-andreact technique was fabricated and tested. Three 1-m long flat racetracks and the common coil dipole model, based on a singlelayer coil and wide reacted Nb 3 Sn cable, have also been fabricated and tested. Extensive theoretical studies of magnetic instabilities in Nb3Sn strands, cable and magnet were performed which led to successful 10 T dipole model. This paper presents the details of the Fermilab's high field accelerator magnet program, reports its status and major results, and formulates the program next steps.

Now physicists at MIT have come up with a blueprint for a device they believe would be able to convert ambient terahertz waves into a direct current, a form of electricity that powers many household electronics. [35] A pair of researchers, one with the Langevin Institute, the other a company called Greenerwave, both in France, has developed a way to use ordinary Wi-Fi signals to perform analog, wave-based computations. [34] A scientist involved in expanding quantum communication to a network of users, is continuing his work at the University of Bristol. [33] In recent years, nanofabricated mechanical oscillators have emerged as a promising platform for quantum information applications. [32] Quantum communication, which ensures absolute data security, is one of the most advanced branches of the "second quantum revolution". [31] Researchers at the University of Bristol's Quantum Engineering Technology Labs have demonstrated a new type of silicon chip that can help building and testing quantum computers and could find their way into your mobile phone to secure information. [30] Theoretical physicists propose to use negative interference to control heat flow in quantum devices. [29] Particle physicists are studying ways to harness the power of the quantum realm to further their research. [28] A fundamental barrier to scaling quantum computing machines is "qubit interference." In new research published in Science Advances, engineers and physicists from Rigetti Computing describe a breakthrough that can expand the size of practical quantum processors by reducing interference. [26] The search and manipulation of novel properties emerging from the quantum nature of matter could lead to next-generation electronics and quantum computers. [25]

Materials with the olivine LixMPO4 structure form an important new class of materials for rechargeable Li batteries. There is significant interest in their electronic properties because of the importance of electronic conductivity in batteries for high rate applications. The density of states of LixMPO4 (x = 0, 1 and M = Fe, Mn) has been determined with the ab initio GGA+U method, appropriate for these correlated electron systems. Computed results are compared with the optical gap of LiFePO4, as measured using UV-Vis-NIR diffuse reflectance spectroscopy. The results obtained from experiment (3.8-4.0 eV) and GGA+U computations (3.7 eV) are in very good agreement. However, standard GGA, without the same level of treatment of electron correlation, is shown to make large errors in predicting the electronic structure. It is argued that olivines are likely to be polaronic conductors with extrinsically determined carrier levels and that their electronic conductivity is therefore not simply related to the band gap.

Optical extinction spectra calculated via multisphere T-matrices for nanoparticles with different concentrations of metals and different architectures (core-shell, inverse core-shell, or alloy) are considered. A method is proposed for determination of architecture of nanoparticles (core-shell or alloy) from only data on the position of plasmon resonance and composition of components. The use of an optical spectrum fitting technique to the spectra of monodisperse noninteracting bimetallic nanoparticles with a predetermined structure appeared to be effective for the determination of the internal structure of nanoparticles, except large nanoparticles with a radius of more than 60 nm containing less than ∼25% silver atoms.

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In this review article we discuss the recent progress in studying ballistic transport for charge carriers in graphene through highly inhomogeneous magnetic field known as magnetic barrier in combination with gate voltage induced electrostatic potential. Starting with cases for a single or double magnetic barrier we also review the progress in understanding electron transport through the superlattices created out of such electromagnetic potential barriers and discuss the possibility of experimental realization of such systems. The emphasis is particularly on the analogy of such transport with propagation of light wave through medium with alternating dielectric constant. In that direction we discuss electron analogue of optical phenomena like Fabry–Perot resonances, negative refraction, Goos–Hänchen effect, beam collimation in such systems and explain how such analogy is going to be useful for device generation. The resulting modification of band structure of Dirac fermions, the emerg...

Iodine adlayers formed on Au(lll) in aqueous KI solution have been studied by ex situ Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and in situ scanning tunneling microscopy (STM). The LEED patterns are described as c(p X vr3R -30 °) where p decreases continuously with increasing emersion potential. By in situ STM, a series of rotated hexagonal structures was observed at positive potentials in addition to the c(p x v~R -30 °) structures. This rotated hexagonal adlattice was also compressed with increasing electrode potential. These results in general confirm the phenomenon of electrocompression of the iodine adlayer on Au(lll) observed by in situ surface X-ray scattering.

We report ballistic magnetoresistance (BMR) values in magnetic nanocontacts for Ni, Co, and Fe. The samples range from atomic nanocontacts (smaller than 1nm cross-section) to stable electrodeposited nanocontacts (up to 30nm cross-section). The experiments are done at room temperature and up to 4kOe applied field. We obtain values of stable BMR up to 700%. By manipulating the resistance and the

The band gap of Cd1-xMgxTe can be easily tuned from 1.48 to 3.5 eV (x = 0 to 1), and hence this material is a potential candidate for developing the wide band gap top cell in tandem solar cells. In this paper, we present an all-sputtered Cd1-xMgxTe/CdS top cell developed on commercial SnO2:F-coated (Tec-7) glass substrates with sheet resistance of

With such a general model, one cannot obtain numerical results, but one can obtain general results which appear to correspond to some of the peculiar properties of liquid helium. Eq. (1) is not the exact Hamiltonian; it can be derived from the Hamil- tonian of a system of ...

We estimate the numerical contribution of the interaction between like defects in glasses for the linewidth (tf Ti') obtained in acoustical experiments. This interaction gives origin to a diffusion process with a very large diffusion constant (D = lO-~cm2 sec'). The thermal conductivity due to this diffusion process is calculated. Its temperature dependence is also obtained.

Vibrational dynamics of binary titanium borides is studied from first-principles. Polarized and unpolarized Raman spectra of TiB, TiB2, and Ti3B4 are reported along with the experimental spectra of commercial powder and bulk TiB2 containing less than 1 wt.% of impurity phases. The X-ray diffraction spectroscopy, applied for phase composition examination of both bulk and powder materials, identifies only the TiB2 phase. The simulated Raman spectra together with literature data support interpretation and refinement of experimental spectra which reveal components arising from titanium dioxide (TiO2) and amorphous boron carbide (B4C) impurity phases as well as graphitic carbon. These contaminations are the by-products of synthesis, consolidation, and sintering aids employed to fabricate powder and bulk titanium diboride.

The correlated metal UCoGe is a weak itinerant ferromagnet with a Curie temperature T C = 3 K and a superconductor with a transition temperature T s = 0.6 K. We review its basic thermal, magnetic  on the macro and microscopic scale  and transport properties, as well as the response to high pressure. The data unambiguously show that superconductivity and ferromagnetism coexist below T s = 0.6 K and are carried by the same 5f electrons. We present evidence that UCoGe is a p-wave superconductor and argue that superconductivity is mediated by critical ferromagnetic spin fluctuations.

Coprecipitated ferrite nanoparticles were coated with carbon using a hydrothermal method. From transmission electron microscope pictures, we could see that the coated iron oxide nanoparticles were spherical in shape with an average diameter of 90 nm. The strong bonding of carbon on the nanoparticle surfaces was checked by noting the C = O and C = C vibrations in Fourier transform infrared spectra. The spin-lattice relaxation process [T 1 ] and spin-spin relaxation process [T 2 ] relaxivities of hydrogen protons in the aqueous solution of coated nanoparticles were determined to be 1.139 (mM•s)-1 and 1.115 (mM•s)-1 , respectively. These results showed that the carboncoated iron oxide nanoparticles are applicable as both T 1 and T 2 contrast agents in magnetic resonance imaging.

YbBa 2 Cu 3 O 7−x (YbBCO) thick films were grown on buffered, cube-textured Nickel tapes by sol-gel dip-coating method. Yb-123 films were prepared using solutions of Yb, Ba, and Cu organometallic compounds. A solution-based Gd 2 O 3 buffer layer was deposited by dipcoating process with excellent texture and uniformity. The texture development and surface morphology of the buffer-layer films were examined by X-ray diffraction, pole figures, and ESEM analysis. Microstructure and characterization of Yb-123 films were done by ESEM, EDS, and XRD analysis. T c and J c were conducted by four-wire measurement method

The oxidation of (Pb,Ge)Te crystal surfaces at ambient temperature and humidity was studied by means of XPS in a time range from minutes to months. Vacuum-cleaved crystal was used for the experiment. It was found that Ge in a PbTe lattice occupies two different positions. At one of them, donor behaviour is revealed and the concentration of donor atoms increases at temperatures lower than those of the cubic-rhombohedral phase transition. It was found that oxidation takes place even after a few minutes of air exposure. Germanium atoms oxidize entirely to oxidation state +4, this being followed by slow oxidation of tellurium atoms from oxidation state −2 to +4. After a long air exposure, significant surface enrichment in Pb was observed.

Silicon thin films grown near the boundary between the amorphous/microcrystalline growth offer superior properties for industrial applications. Series of silicon samples, in which crossing of this transition region was achieved by changing a single technological parameter (dilution of silane in hydrogen, deposition temperature, sample thickness) were used to test our model of transport, connecting the macroscopically observed transport properties and the crystallinity, hydrogen content, grain size and grain boundaries. Microscopic study by AFM led to the formulation of the geometrical model of growth of mixed phase Si. The demand for research of microcrystalline or polycrystalline silicon prepared at low substrate temperatures is stimulated by the use of cheap plastic substrates. In addition to a direct deposition an alternative technology, such as metal-induced crystallization supported by the electric field is discussed. Possible future application of thin silicon films, for example in a "nanolithography", is also shown. *

The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt complex has been confirmed by XRD analysis. The DSC thermograms show two Tg's for PVAc–PMMA blend. A decrease in Tg with the LiClO4 content reveals the increase of segmental motion. Conductance spectra results are found to obey the Jonscher's power law and the maximum dc conductivity value is found to be 1.76 × 10− 3 S cm− 1 at 303 K for the blend polymer complex with 20 wt.% LiClO4, which is suitable for the Li rechargeable batteries. The conductivity–temperature plots are found to follow an Arrhenius nature. The dc conductivity is found to increase with increase of salt concentration in the blend polymer complexes.

We report some time-resolved luminescence measurements on the conjugated polymer, MEH-PPV, that show a marked dependence on the intensity of the excitation light. At low laser powers the excited state lifetime is longer than has been reported previously and is consistent with emission from an interchain excitation that has low oscillator strength and hence a long natural radiative lifetime. We rationalise these data with a simple scheme that summarises the excited state kinetics in this and other conjugated, electroluminescent polymers.

Guiding 3-keV Ne 7+ ions through nanocapillaries in insulating polyethylene terephthalate was investigated as function of the capillary diameter. Highly parallel capillaries with a density of 4 × 10 6 cm −2 and diameters of 100, 150, 200, 300, and 400 nm were utilized. The characteristic charges governing the charge evolution of the total ion yield were found to be independent of the capillary diameter. However, certain dynamic properties were found to change significantly with this diameter: The transmission profiles of the 100 nm capillaries are broad and structureless, whereas those for 300 nm are composed of three peaks and the mean angle oscillates with deposited charge. At equilibrium the total ion yield was studied as a function of the tilt angle. The results were used to evaluate guiding angles, which were found to be almost constant near 5.5 • with varying capillary diameter similarly as the characteristic charge governing the charge evolution. The width of the transmission profiles are found to decrease from 3.3 • to 1.7 • with increasing capillary diameter from 100 to 400 nm. Model considerations were applied to interpret the results.

Gold nanoparticles protected by a binary mixture of thiolate molecules have a ligand shell that can spontaneously separate into nanoscale domains. Complex morphologies arise in such ligand shells, including striped, patchy, and Janus domains. Characterization of these morphologies remains a challenge. Scanning tunneling microscopy (STM) imaging has been one of the key approaches to determine these structures, yet the imaging of nanoparticles' surfaces faces difficulty stemming from steep surface curvature, complex molecular structures, and the possibility of imaging artifacts in the same size range. Images obtained to date have lacked molecular resolution, and only domains have been resolved. There is a clear need for images that resolve the molecular arrangement that leads to domain formation on the ligand shell of these particles. Herein we report an advance in the STM imaging of gold nanoparticles, revealing some of the molecules that constitute the domains in striped and Janus gold nanoparticles. We analyze the images to determine molecular arrangements on parts of the particles, highlight molecular "defects" present in the ligand shell, show persistence of the features across subsequent images, and observe the transition from quasimolecular to domain resolution. The ability to resolve single molecules in the ligand shell of nanoparticles could lead to a more comprehensive understanding of the role of the ligand structure in determining the properties of mixed-monolayer-protected gold nanoparticles.

We report pressure and temperature dependent electrical resistivity measurements in the Ce 2 Rh 1Àx Ir x In 8 alloys. Our results revealed two phases with zero resistance. One of these phases is induced by pressure, occurring for a range of compositions situated near the Rhrich extreme, consistent with the behavior observed for the pure Ce 2 RhIn 8 compound. The second transition occurs for intermediate concentrations ðx$0:520:7Þ, and in sharp contrast with the first transition, is progressively eliminated by the application of pressure. We compare the findings in the Ce 2 Rh 1Àx Ir x In 8 alloys to its related CeRh 1Àx Ir x In 5 , discussing how the occurrence of the superconducting phases may become unfavorable for the bi-layer alloys due to higher dimensionality and stronger disorder. r

Heterocyclic ligands are common sensitizers for the lanthanide ions emission upon UV irradiation. Of particular interest are Tb(III) and Eu(III) ions in combination with acyclic, macrocyclic and macropolycylic ligands incorporating heterobiaryls, such as 2,29-bipyridyl, 1,10-phenanthroline, 1,19-biquinoline, 3,39-biisoquinoline, and their derivatives. Much more powerful sensitizers are the same systems bearing N-oxide functions, furthermore their complexes are more stable than the parent heterocycles. Such luminescent materials are the basis for time-resolved fluoroimmunoassays displaying very high sensitivity, and serve as materials for advanced medical diagnostics. In this short review, a brief presentation will focus on state-of-the-art photochemistry and photophysics of the lanthanide complexes of heterocyclic and N-oxide-incorporating heterocyclic systems.

The preparation and characterization of Langmulr-Blodgett (LB) films of mesoporphyrin IX dimethylester indium chloride are reported. The utility of complementary experimental techniques such as electron diffraction, polarized visible spectroscopy and cyclic voltammetry in yielding information about molecular orientatton and interactions is highlighted. Our results are consistent w~th verhcal packing of the porphyrin ring on the aqueous subphase and transfer of the material in a similar orientation onto a number of different substrates. From polarized UV-visible spectroscopic measurements an average tilt angle 0 between molecular planes and substrate of 64 ° _+ 15 ° is calculated. An area per molecule on the subphase and m the LB films of 0.55 nm 2 ts obtained from pressure-area curves and coulometrtc measurements respectively. A high degree of crystallimty in the layers is apparent from selected area electron diffraction patterns and the films degrade rapidly on exposure to the electron beam. There is considerable interaction between molecules m the films and this leads to peak broadening in both visible absorption spectra and cyclic voltammograms. An underpotential of 700 mV for the reduction of the porphyrin is consistent with surface potential measurements reported earlier.

Fluids in porous media are commonly studied with analytical or simulation methods, usually assuming that the host medium is rigid. By evaluating the substrate’s response (relaxation) to the presence of the fluid we assess the error inherent in that assumption. One application is a determination of the ground state of 3He in slit and cylindrical pores. With the relaxation, there results a much stronger cohesion than would be found for a rigid host. Similar increased binding effects of relaxation are found for classical fluids confined within slit pores or nanotube bundles.

It is well known that the existing calculations for helium scattering by solid surfaces, made on the first-order distorted-wave Born approximation, within the one-phonon approximation, disagree qualitatively with experiment at low energies and temperatures. Generally, the calculations give sticking probabilities which are too low and which have the wrong trend with incident energy: further, the calculations are incorrect in the limit of zero incident energy. We investigate whether those calculations may be modified in order to correct them and to help them agree better with experiment. The modifications we make are, essentially, the introduction of reflection coefficients and the consideration of surface excitations (modes) different from those considered before.

The chemical bonding and geometric structure of acetylene adsorbed on Cu(1 1 0) is analyzed using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) in combination with density functional theory (DFT) total energy geometry optimizations and spectral calculations. XPS reveals two different adsorbed species at liquid nitrogen temperature. The molecular alignment is deduced from angle-resolved XAS, revealing that in one site the molecules are aligned with the C-C axis along the [0 0 1] direction and in the other site with an average angle of 35°to the Cu rows. The position of the shape resonance is used to deduce a C-C bond length of 1.35 Å , which is close to the values obtained from the DFT geometry optimizations. XES reveals strong r-p mixing and new occupied states close to the Fermi level, originating from the out-of-plane p* orbital, which becomes occupied upon adsorption in agreement with the Dewar-Chatt-Duncanson model of the bonding.

In this work, we use the geometric theory of defects to investigate a continuous distribution of screw dislocations. We analyze the dynamics of a quantum particle in the presence of a density of screw dislocations. We obtain the energy levels and eigenfunctions for the particle in this background. We demonstrate that this quantum dynamics is similar to the dynamics of a charged particle in the presence of an external magnetic field. In addition, we introduce an external magnetic field and perform the calculations of the eigenfunctions and eigenvalues for the particle in this case.

We report the effect of average A-site cation radius on the structural, magnetic and electrical properties of electron doped manganite La 0.7 Ce 0.3 MnO 3 thin films. A site cation radius hr A i is varied systematically by partially replacing La C3 ions by smaller Y C3 ions in the parent compound. The carrier doping, i.e. the fraction of tetravalent Ce atoms at the A-site was kept at 30%. A series of La 0.7Kx Y x Ce 0.3 MnO 3 (xZ0, 0.05, 0.1, 0.15 and 0.25) thin films were prepared under identical conditions by using pulsed laser deposition technique. Metal-insulator transition temperature (T p ) and the ferromagnetic Curie temperature (T c ) are found to be decreasing significantly with increasing yttrium concentration, i.e. decreasing hr A i. The resistivity (r) at T p increases by one order of magnitude when the yttrium concentration is increased from xZ0 to 0.25, while magnetization decreases with decreasing hr A i. Magnetoresistance as measured under field of 1 T is significant near T c . Structural analysis reveals the films are having single phase and c-axis lattice parameter decreasing linearly as hr A i decreases. There is no marked difference in surface morphology of samples with different yttrium concentration. From EDX the Y:Ce:Mn ratio were consistent within 5% of the nominal composition. q

Polycrystalline samples of FeSe 1-x Te x (x = 0.00, 0.25, 0.50, 0.75 and 1.00) were synthesized by solid-state reaction to study the effects of substituting Se with Te in the system. The magnetization properties of the resulting compounds were investigated and the crystallographic structures of the samples analyzed through X-ray diffraction. Mössbauer spectroscopy was used to determine the ionic state of the Fe ions and the hyperfine fields. The magnetic susceptibility curves of the samples with x = 0.25, 0.50 and 0.75 show superconducting behavior. The lattice parameters and the cell volume increase monotonically with increasing Te concentration and the Mössbauer spectra reveal the absence of internal magnetic hyperfine fields.

The two-dimensional hybrid organic-inorganic materials Zn 2 -Cr and Zn 2 -Al-LDHs (Layered Double Hydroxides) containing 4-(1H-pyrrol-1yl)benzoate anions as the interlayer anions were synthesized by the co-precipitation method at constant pH followed by subsequent hydrothermal treatment for 72 h. The materials were characterized by PXRD, 13 C CP-MAS NMR, ESR, TGA, and TEM. The basal spacing found by the X-ray diffraction technique is coincident with the formation of bilayers of the intercalated anions. Solid-state 13 C NMR and ESR data strongly suggest the partial in situ polymerization of the 4-(1H-pyrrol-1yl)benzoate anions during coprecipitation. q

The microstructure simulation of spinodal decomposition was carried out in the aged Cu-70 and 90 at.% Ni alloys, based on a solution of the non-linear Cahn-Hilliard partial differential equation by the finite difference method. The calculated concentration profiles were compared with the experimental ones determined by atom-probe field ion microscope analyses of the solution treated and aged Cu-70 at.% Ni alloy samples. Both the numerically simulated and experimental results showed a good agreement for the concentration profiles and microstructure evolution in the aged Cu-Ni alloys. A very slow growth kinetics of phase decomposition was observed to occur in this type of alloy. The morphology of decomposed phases consists of an irregular shape with no preferential alignment in any crystallographic direction. The wavelength of composition modulation was determined numerically to be about 2 nm and it remained constant after aging at 573 K for times as long as 8889 h. No phase decomposition was observed to occur for the numerical simulation of aging at temperatures lower than 523 K for a time as long as 1 year.

A photosensitizer is defined as a chemical entity, which upon absorption of light induces a chemical or physical alteration of another chemical entity. Some photosensitizers are utilized therapeutically such as in photodynamic therapy (PDT) and for diagnosis of cancer (fluorescence diagnosis, FD). PDT is approved for several cancer indications and FD has recently been approved for diagnosis of bladder cancer. The photosensitizers used are in most cases based on the porphyrin structure. These photosensitizers generally accumulate in cancer tissues to a higher extent than in the surrounding tissues and their fluorescing properties may be utilized for cancer detection. The photosensitizers may be chemically synthesized or induced endogenously by an intermediate in heme synthesis, 5-aminolevulinic acid (5-ALA) or 5-ALA esters. The therapeutic effect is based on the formation of reactive oxygen species (ROS) upon activation of the photosensitizer by light. Singlet oxygen is assumed to be the most important ROS for the therapeutic outcome. The fluorescing properties of the photosenisitizers can be used to evaluate their intracellular localization and treatment effects. Some photosensitizers localize intracellularly in endocytic vesicles and upon light exposure induce a release of the contents of these vesicles, including externally added macromolecules, into the cytosol. This is the basis for a novel method for macromolecule activation, named photochemical internalization (PCI). PCI has been shown to potentiate the biological activity of a large variety of macromolecules and other molecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins, immunotoxins, gene-encoding plasmids, adenovirus, peptide-nucleic acids and the chemotherapeutic drug bleomycin. The background and present status of PDT, FD and PCI are reviewed.

This work comprises calculations using the Frenkel±Kontorova and doublechain models, which led to new results explaining the experimental diffraction pattern of K-hollandite. The use of a deformable host chain and a Lennard-Jones-like interchain interaction gives the best results. From these calculations, it can also be concluded that the guest as well as the host are deformed and that the system is pinned. The inclusion of Debye±Waller factors as ®tting parameters is also discussed, with the conclusion they should not be used in the case of the double-chain model.

Calcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO), thin films have been fabricated by Metal Organic Chemical Vapor Deposition (MOCVD) on LaAlO 3 (100) single crystal substrates. Depositions have been carried out from a molten mixture consisting of the Ca(hfa) 2 •tetraglyme, Ti(tmhd) 2 (O-iPr) 2 , and Cu(tmhd) 2 [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione; O-iPr = iso-propoxide] precursors. Post-deposition annealing treatments have been performed at 1100°C for long time (24 h) as well as by rapid thermal annealing (RTA) processes. Since structural and chemical properties of CCTO ceramics greatly affect the resulting dielectric properties, accurate structural, morphological and compositional characterizations of the annealed samples have been performed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). Oriented films have been obtained after both long time annealings and RTA processes, while different morphologies have been observed: ∼ 600 nm wide rounded grains and very large (∼5 μm) squared grains, respectively.

The propagation of guided optical modes and surface acoustic waves in GaN layers grown on sapphire by MOCVD technique is experimentally studied. The effective refractive indices of guided optical modes are measured using the prism coupling technique, and the thickness and refractive indices of the layer are evaluated. The surface acoustic wave velocities are measured by acoustooptic diffraction technique, revealing a strong acoustic dispersion. The evaluation of GaN layer thickness from the SAW measurements is demonstrated.

We present results of sound propagation measurements and neutron scattering experiments on one and the same sample of the heavy fermion substance UPt 3. From these experiments we deduce a B-T phase diagram of the small-moment spin density wave region in this compound for magnetic field Bile.

A preparation process for YBalCu,O, (afterhere YBCO) superconducting ceramics is presented, in which partial substitution of the copper oxide component by metallic copper is used. The results of an investigation for improving the critical current in YBCO superconductors are also presented. These results show that the YBCO superconductors can be successfully prepared by using the partial metallic copper substitution process. The sintered superconducting ceramics all contain the same pure single phase. The critical current J , of these samples is linearly dependent on the substituted metallic copper content up to 50 wt%. For samples substituted with about 50 wtoh of the copper content J , is improved by a factor of about 1.5, i.e. J , > 300 A/cm2. The experimental values of J , measured at a temperature of 77 K and zero field show that J , is limited by the intergrain tunneling weak-link effect. The linear dependence of J , on the normal state tunneling resistance is in good agreement with the Ambegaokar-Baratoff theory. The energy gap of YBCO superconductors is estimated based on the Ambegaokar-Baratoff theory to be as high as 24 = 7.84kT.

This paper reports on the preparation of titanium (IV) oxide films via the improved atmospheric pressure barrier torch discharge (BTD) deposition. This approach is a modification of the atmospheric pressure glow discharges (APGDs) ranking among plasma enhanced chemical vapor deposition (PECVD) techniques. These methods are based on plasma-chemical reactions of the precursors' vapors occurring in the active plasma environment. The layers are produced in terms of heterogeneous recombination reactions of the high active species on the supporting surface. The major treated topic comprises the influence of the used support on the physical properties of the layers. A set of three different supports was used including quartz slides (nonconducting, dielectric), silicon discs (semi-conducting) and polished Ni sheets (conducting). Crystallographic structure, surface roughness, surface wettability and the film thickness were assessed and used as a set of physical properties to be discussed and compared for each of the films and mutually. In parallel the qualitative analysis of the emission spectra of the barrier torch discharge during the deposition process was also presented. Different conductive connection of plasma stream with the substrate crucially influences the temperature of this substrate. It has a direct effect mainly on the crystallinity and morphology of the films and also on the plasma parameters. This knowledge might be used as a tool for the optimization of deposition conditions. Photocatalytic functionality of the layers was quantified in a simple test based on the photocatalytic oxidation of Rhodamine B (C 28 H 31 ClN 2 O 3 ) under UV radiation.