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There is a growing interest in sodium hyaluronate for the clinical management of patients who undergo functional endoscopic sinus surgery for chronic rhinosinusitis, because of the mucosal regenerative properties of this macromolecule. However, its role in post-operative care is still debated. This study aimed to evaluate the effect of sodium hyaluronate administered via nasal irrigation with saline, in the post-operative period, after functional endoscopic sinus surgery.
A multicentric, prospective, randomised, double-blind, parallel group study was conducted on 56 consecutive patients who underwent functional endoscopic sinus surgery for chronic rhinosinusitis without polyps. Group 1 received the standard therapy of normal saline; group 2 received saline plus sodium hyaluronate.
Both objective and subjective measurements, in terms of endoscopic appearance and patient-reported satisfaction, were significantly better in group 2 compared to group 1.
Sodium hyaluronate may be a useful adjunct to nasal saline irrigation in the early post-operative period following functional endoscopic sinus surgery.
The Caltech imaging γ-ray telescope was launched by balloon from Alice Springs, NT, Australia and performed observations of the galactic center during the period 12.62 to 13.00 April 1988 UT. The first coded-aperture images of the galactic center region at energies above 30 keV show a single strong γ-ray source which is located 0.7±0.1° from the galactic nucleus and is tentatively identified as 1E1740.7-2942. If the source is at the distance of the galactic center, it is one of the most luminous objects in the galaxy at energies from 35 to 200 keV.
Hydrogen with an energy of 300 eV was implanted into single crystalline CuInSe2 samples at temperatures of 200 °C and 300 °C during implantation. We found that the hydrogen is not limited to the expected implantation depth but diffuses into the bulk of the sample. The hydrogen concentration ranges from 1019 H/cm3 in a depth of about 300 nm up to some 1021 H/cm3 next to the surface and resembles a diffusion profile. The hydrogen induced change of composition was not only at the surface, but also up to a depth of about 200 nm similar to that of the hydrogen profile. Mainly a Cu deficiency after hydrogen implantation could be observed and is explained as the passivation of VCu by hydrogen and the additional production of VCu by the induced band-bending.
We report on a novel ion beam selenization process. The reactive chalcogen component Se and a significant part of the thermal energy needed for CIGS formation is delivered directly into the growing surface by a low energy Se ion beam from a broad beam ion source. This highly controllable technique with respect to ion energy, dose and uniformity and with scale- up capabilities can be used in two ways either for selenization of metallic Cu/(In,Ga) thin film stacks or in co-deposition. In the case of co-deposition the CIGS growth temperature can be reduced to < 400°C
Besides the description of the method we present results of Se ion beam analysis and properties of CIGS thin films, produced by the novel selenization process.
Sub-lithographic copper damascene lines were fabricated to investigate
already today the physical phenomena and scaling limits of metallic
conductors in the metallization systems of chip generations which are
believed to be in production 10 years from now and later. Using standard
manufacturing processes and state-of-the-art process tools, including
standard lithography tools, narrow copper lines were fabricated at the
expense of a relaxed pitch by use of a removable spacer technique. These
copper nano interconnects were passivated and subjected to electrical
measurements. Our results show that continuous down scaling to increase
device performance will result in an unfavorable increase of the electrical
resistivity of copper in stateof-the-art metallization schemes. Electrical
measurements over a wide range of temperatures down to cryogenic
temperatures reveal the limited potential of cooling to reduce resistivity
of conductors as lateral dimensions will be shrinked down to the sub-100nm
regime. By down scaling of copper diffusion barriers in damascene trenches,
barrier functionality was demonstrated after high temperature anneals and
excessive bias-temperature stress tests for films meeting or even exceeding
end-of-roadmap thickness requirements. An analysis of the temperature
dependence of the leakage current measured at very high electric fields
applied between neighboring damascene lines suggests the conduction
mechanism in the SiO2 used as intermetal dielectric to be
Frenkel-Poole type rather than Schottky emission. Electromigration life
times of sub-100nm copper lines embedded in oxide were found to be
comparable with those obtained for similar structures fabricated with
today's feature sizes.
-Heteroepitaxial superconducting Bi,Sr2CaCu2Ox (BSCCO 2212) thin films have been formed by solid phase epitaxy from amorphous films deposited on (100) LaA1O3 single crystal substrates by organometallic chemical vapor deposition. The epitaxial structure of the film is confirmed by x-ray diffraction including θ/2θ and Φ (in plane rotation) scans. Cross-sectional high resolution transmission electron microscopy indicates that the film-substrate interface is nearly atomically abrupt. Improvements in superconducting properties of the epitaxial thin films are noted in comparison to highly textured films deposited on MgO.
The synthesis of superconducting Tl-Ba-Ca-Cu-O thin films on metal foils (Au and Ag) by metal-organic chemical vapor deposition (MOCVD) has been investigated. Ba-Ca-Cu-O-(F) films are first prepared via MOCVD using fluorinated “second generation” metal-organic precursors. After an intermediate anneal with water vapor-saturated oxygen to promote removal of F, Tl is introduced by annealing in the presence of a mixture of oxides (Tl2O3, BaO, CaO, CuO) of a specific composition. Characterization of the thin films by scanning electron microscopy, EDX, x-ray diffraction, and variable temperature magnetization measurements has been carried out. High temperature superconductor (HTS) films of Tl2Ba2Ca1Cu2O8−x on Au foil exhibit a magnetically derived Tc = 80K and a high degree of texturing with the crystallite c-axes oriented perpendicular to the substrate surface as evidenced by enhanced (000 x-ray diffraction reflections. Thin film coverage on Ag foil becomes non-contiguous during the (Tl2O3, BaO, CaO, CuO) mixture anneal.
Ba1−xSrxTiO3 thin films were deposited over the entire solid solution range by low pressure metal-organic chemical vapor deposition. The metal-organic precursors employed were titanium tetraisopropoxide and barium and strontium(hexafl uoroacetylacetonate)2·tetraglyme. The substrates used were LaAlO3 and (100) p-type Si. Ba1−xSrxTiO3 films deposited on LaAlO3 were epitaxial, while the films deposited on Si showed no texture. Auger spectroscopy indicated that single phase Ba1−xSrxTiO3 films did not contain detectable levels of fluorine contamination. The dielectric constant was found to depend upon the solid solution composition x, and values as large as 220 measured at a frequency of 1 MHz were obtained. The resistivities of the as-deposited films ranged from 103 to 108 Ω-cm. Temperature dependent resistivity measurements indicated the films were slightly oxygen deficient.
Superconducting thin films of Tl2Ba2Ca2Cu3O10−x (TL-2223) have been grown on single crystal (110) LaAlO3 using a two-step process. Ba2Ca2Cu3Ox precursor films are deposited via metal-organic chemical vapor deposition (MOCVD) in a horizontal hot walled reactor. The second generation precursors Ba(hfa)2•tet, Ca(hfa)2•tet, and Cu(hfa)2 (hfa = hexafluoroacetylacetonate, tet = tetraglyme) were used as volatile metal sources due to their superior volatility and stability. Tl was introduced into the film via a high temperature post anneal in the presence of a Tl2O3:BaO:CaO:CuO pellet (1:2:2:3 ratio). Low O2 partial pressures were used to reduce the temperature in which the TI-2223 phase forms and to improve the surface morphology associated with a liquid phase intermediate. Films are highly oriented with the c-axis perpendicular to the substrate and a-b axis epitaxy is seen from x-ray φ- scans. The best films have a resistively measured Tc of 115K and a magnetically derived Jc of 6×105 A/cm2 (77K, 0 T). Preliminary surface resistance measurements, using parallel plate techniques, give Rs = 0.35 mΩ at 5K (ω = 10 GHz).
The intercalation properties of the layered V2O5 xerogel towards conductive polymers are described. The systems intercalated with polyaniline show post-intercalative redox polymerization caused by ambient oxygen to give products with enhanced conductivity. For the first time the role of oxygen in this intercalation reaction has been unequivocally identified. We also report the synthesis and some properties of a new intercalation compound in which the guest species is poly(ethylene oxide), an insulating polymer.
The frequency dependent electrical properties of the intercalated polypyrrole/V2O5 system have been measured. This study continues the investigation into the charge transport mechanisms that have been identified in these layered polymer/inorganic composites. The polypyrrole/V2O5 material is prepared by in-situ oxidative polymerization of pyrrole in the intralamellar space of the V2O5 xerogel. This process produces a layered, two-dimensional structure in which the charge transport properties result from two parallel conduction paths: the polypyrrole chains and the V2O5 layers. Impedance spectroscopy data have been collected from free-standing film samples of the layered polypyrrole/V2O5. The experiments were conducted over the frequency range of 10 Hz to 0.5 GHz and a temperature range of 77 to 310 K. The polypyrrole/V2O5 impedance results are presented in various equivalent forms and compared to data collected from pristine V2O5·nH2O, and reduced Cs0.14V2O5·nH2O.
Thin films of the Bi-2212 and T1–2212 compounds were prepared by MOCVD deposition techniques. Resistivity versus temperature and critical current density measurements were used to characterize the electrical properties. An analysis of the data based on a proposed model determined the influence of intragranular weak links. Thin film samples in both systems with near optimum oxygen doping showed a correlation between the slope and magnitude of the resistivity in the normal state. Samples with reduced oxygen content displayed a strong increase in the intragrain boundary resistance, consistent with weak link defects. The results agree with a similar analysis of YBCO samples and support a common mechanism for the development of weak links in cuprates.
A solid state chemistry synthetic approach towards identifying new materials with potentially superior thermoelectric properties is presented. Materials with complex compositions and structures also have complex electronic structures which may give rise to high thermoelectric powers and at the same time possess low thermal conductivities. The structures and thermoelectric properties of several new promising compounds with K-Bi-Se, K-Bi-S, Ba-Bi- Te, Cs-Bi-Te, and Rb-Bi-Te are reported.
New Bi-based chalcogenide compounds have been prepared using the polychalcogenide flux technique for crystal growth. These materials exhibit characteristics of good thermoelectric materials. Single crystals of the compound CsBi4Te6 have shown conductivity as high as 2440 S/cm with a p-type thermoelectric power of ≈ +110 μV/K at room temperature. A second compound, β-K2Bi8Se13 shows lower conductivity ≈ 240 S/cm, but a larger n-type thermopower ≈ −200 μV/K. Thermal transport measurements have been performed on hot-pressed pellets of these materials and the results show comparable or lower thermal conductivities than Bi2Te3. This improvement may reflect the reduced lattice symmetry of the new chalcogenide thermoelectrics. The thermoelectric figure of merit for CsBi4Te6 reaches ZT ≈ 0.32 at 260 K and for β-K2Bi8Se13 ZT ≈ 0.32 at room temperature, indicating that these compounds are viable candidates for thermoelectric refrigeration applications.
Bi2Sr2CaCu2O8 thin films have been prepared in situ by low pressure metalorganic chemical vapor deposition using fluorinated β–diketonate precursors. The influence of the growth conditions on the oxide phase stability and impurity phase formation was examined as well as the superconducting properties of the films. Thin films deposited on LaAIO3 substrates were epitaxial as confirmed by x-ray diffraction measurements, including θ-2θ and φ scans. Four probe resistivity measurements showed the films to be superconducting with a maximum Tc0 of 90 K without post annealing. This Tc0 is among the highest reported for thin films of the BSCCO (2212) phase, and approaches reported bulk values.