This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11-year solar cycle. It is ...based on attribution analysis using multiple nonlinear techniques (support vector regression, neural networks) besides the multiple linear regression approach. The analysis was applied to several current reanalysis data sets for the 1979-2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how these types of data resolve especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the tropical stratosphere were found to be in qualitative agreement with previous attribution studies, although the agreement with observational results was incomplete, especially for JRA-55. The analysis also pointed to the solar signal in the ozone data sets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. The results obtained by linear regression were confirmed by the nonlinear approach through all data sets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. The seasonal evolution of the solar response was also discussed in terms of dynamical causalities in the winter hemispheres. The hypothetical mechanism of a weaker Brewer-Dobson circulation at solar maxima was reviewed together with a discussion of polar vortex behaviour.
•UNCD and DLC films were modified by UV/O3 treatments, O2 or NH3-containing plasmas.•Surface composition, wettability and surface energy change upon modifications.•Higher efficiency of UNCD ...modifications was observed.•Cell attachment and growth were influenced by the surface termination and roughness.
Diamond and diamond-like carbon (DLC) films possess a set of excellent physical and chemical properties which together with a high biocompatibility make them attractive candidates for a number of medical and biotechnological applications. In the current work thin ultrananocrystalline diamond (UNCD) and DLC films were comparatively investigated with respect to cell attachment and proliferation after different surface modifications. The UNCD films were prepared by microwave plasma enhanced chemical vapor deposition, the DLC films by pulsed laser deposition (PLD). The films were comprehensively characterized with respect to their basic properties, e.g. crystallinity, morphology, chemical bonding nature, etc. Afterwards the UNCD and DLC films were modified applying O2 or NH3/N2 plasmas and UV/O3 treatments to alter their surface termination. The surface composition of as-grown and modified samples was studied by X-ray photoelectron spectroscopy (XPS). Furthermore the films were characterized by contact angle measurements with water, formamide, 1-decanol and diiodomethane; from the results obtained the surface energy with its dispersive and polar components was calculated. The adhesion and proliferation of MG63 osteosarcoma cells on the different UNCD and DLC samples were assessed by measurement of the cell attachment efficiency and MTT assays. The determined cell densities were compared and correlated with the surface properties of as-deposited and modified UNCD and DLC films.
In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in ...erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10-30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4-6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20-25%. A similar decrease was found in the case of O3 . The plume parameterization suppressed the ship induced ozone production by 15-30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.
This study presents an interactive coupling system of the regional climate model RegCM3 and the chemistry transport model CAMx, called RegCMCAMx. This system provides an advancement from offline ...coupling methods already in use. In RegCMCAMx, the radiative effects of tropospheric ozone, sulfates and black and organic carbon were considered. A series of annual sensitivity simulations were carried out for the year 2005 over a European domain, where ozone and/or aerosols were interactively coupled (taking their radiative feedbacks into account). The simulated concentrations of ozone, nitrogen dioxide, sulfur dioxide, sulfate and carbonaceous aerosol were validated against surface measurements. The coupling was evaluated by simulating 2 m temperature as well. The model satisfactorily reproduced near-surface ozone, especially in summer, and made reasonable predictions for monthly sulfate aerosol concentrations. Deficiencies were identified in simulating nitrogen (underprediction), sulfur oxides (overprediction) and carbonaceous aerosols (underprediction). The performance of the coupling system compared to non-coupled data was analyzed, and significant improvement of the model was found in terms of reproducing 2 m temperature, mainly for interactively coupled ozone. The short-term climate response of interactively coupled chemistry/aerosol was analyzed for the first time by this coupling model as well. The seasonally averaged temperature perturbation caused by coupled ozone/aerosols ranged from −1.5 to +1.5°C, not only near the surface but also at higher altitudes. Despite expectations, the surface radiative forcing due to aerosols did not correlate with the induced temperature changes, reflecting the complexity of the processes when ozone and/or aerosols perturb the overall dynamics of the atmosphere. The limitations of the newly established coupling system and the potential for future development are discussed.
Biological, physical and mechanical properties of silver-doped layers of titanium alloy Ti6Al4V and 316L steel prepared by pulsed laser deposition were studied. Metallic silver-doped coatings could ...be a new route for antibacterial protection in medicine. Thin films of silver and silver-doped materials were synthesized using KrF excimer laser deposition. The materials were ablated from two targets, which were composed either from titanium alloy with silver segments or from steel with silver segments. The concentration of silver ranged from 1.54 at% to 4.32 at% for steel and from 3.04 at% to 13.05 at% for titanium alloy. The layer properties such as silver content, structure, adhesion, surface wettability, and antibacterial efficacy (evaluated by Escherichia coli and Bacillus subtilis bacteria) were measured. Film adhesion was studied using scratch test. The antibacterial efficacy changed with silver doping up to 99.9 %. Our investigation was focused on minimum Ag concentration needed to reach high antibacterial efficiency, high film adhesion, and hardness.
Silver doped diamond-like carbon layers were deposited by dual pulsed laser deposition using two KrF excimer lasers. The concentration of Ag, determined by XPS and WDS, moved from zero to ~10at%. We ...found that the sp2/sp3 ratio, film roughness and the number of droplets (SEM and AFM) increased with increasing silver concentration. The sp3 content measurement (XPS) was influenced by ion cluster surface sputtering and varied from 71.0% (undoped DLC) to 36.2% (for 9.3at% Ag). Transmission was measured on the scale from 200nm to 1100nm, and decreased with increasing silver content. An increase of Ag content has an effect on the decrease of the storage modulus (E′) and the indentation hardness (HIT). The highest values HIT=51.9GPa and E′=270.6GPa were measured on a sample with 0at% Ag. The lowest values HIT=26.0GPa and E′=180.2GPa were measured on a sample of 9.3at% Ag. Film adhesion was studied using the scratch test and was up to 20.8N for the highest Ag concentration. The contact angle (CA) measurements for water showed that the CA of Ag-DLC films was higher (78°-98°) that of DLC film (77°). The surface free energy of DLC and of Ag-DLC was about 40mJ·m−2. Antibacterial properties were studied using gram positive and gram negative bacteria. The antibacterial effects increased with the Ag concentration and were ~99.9% after 24h for the layers with the highest silver content (9.3at%). Our results demonstrate that the Ag-doped DLC films are potentially useful biomaterials having both good mechanical properties and antimicrobial characteristics.
Unique manufacturing technique dual pulsed laser deposition was applied on hydrogen-free diamond-like carbon doped by Ag including topological, physical and antibacterial characterization.
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•DLC and silver doped DLC layers were prepared by dual pulsed laser deposition.•Growing concentration of Ag increases bactericidal properties of Ag-DLC coatings.•Coatings hardness and storage modulus decrease in presence of silver content.•Adhesion of layers to metal substrates increased with silver content.•The resulting coatings are expected to improve biomedical implant performance.
Global spatial distribution of oscillations in the period bands linked to the quasi-biennial oscillation (QBO) and to the 11-year sunspot cycle (SSC) was investigated using the pseudo-2D wavelet ...transform. The results were obtained for the ERA-40, NCEP-DOE 2, NCEP/NCAR, and Twentieth Century Reanalysis V2 datasets. Those included time series of air temperature and zonal and meridional wind velocities were examined for all reanalyzed series from 1,000 up to 10 hPa. Most of the datasets covered the second half of the twentieth century. The results are generally in agreement with other related studies, and they point to the presence of the QBO in the tropical stratosphere along with the regions of induced changes in residual circulation, temperature, or ozone amount across extratropics. The SSC imprint is located mainly over similar locations showing that the cycles’ signals are mutually affected there.
Diamond-like carbon (DLC) and titanium-doped DLC thin films were prepared by unique hybrid system consisting of pulsed laser deposition, ion source (bombardment) and magnetron sputtering. The ...influence of deposition parameters (ion energies, deposition pressures and magnetron power) on composition and physical properties was studied. Composition and
sp
3
/
sp
2
ratio were determined by XPS.
sp
3
/
sp
2
ratio was in the range from 1.4 to 2.2 for undoped DLC and from 3.4 to 4.8 for Ti-DLC. AFM showed that the layers were smooth, but with small amounts of random droplets. The measurements of the contact angle and determination of surface free energy were made for water, diiodomethane and ethylene glycol. Hardness and reduced Young’s modulus varied from 20 to 31 GPa and from 182 to 276 GPa, respectively. Film adhesion was determined by scratch test;
L
C3
reached 23 N for DLC and 27 N for TiDLC. Optimization of
sp
3
/
sp
2
ratio, hardness and adhesion to biomedical alloys will advance the DLC coatings usability in the field of implantology.
In the presented paper, we describe an analysis of spatial patterns of the approximate 8 years cycle identified in the NCEP/NCAR and ERA-40 reanalyzed temperature series. The temperature series are ...examined by the pseudo-2D wavelet transform (p2D-WT) at 17 geopotential levels, ranging from 1000 hPa to 10 hPa. The results differ significantly for the NCEP/NCAR and for the ERA-40 temperature series. For the NCEP/NCAR dataset, oscillation of about 8 years is distinct over large areas at almost every analyzed level. At lower heights, the regions with significant presence of the periodicity are less compact and pronounced than at higher geopotential levels. The occurrence of the analyzed period is generally strongest in the equatorial and tropical areas. For the ERA-40 dataset, the approximate 8 years cycle is detected in substantially fewer grid points and the spatial patterns generally do not conform to the analysis of NCEP/NCAR series. These results indicate that a frequency analysis of the reanalysis datasets should only be interpreted after careful discussion and that the reliability (in the sense of frequency characteristics) of the reanalyzed temperature series still needs to be studied.
Hydroxyapatite layers with silver doping from 0.06at.% to 14at.% were prepared by laser deposition. The films' physical properties such as morphology, composition, crystallinity, Young's modulus and ...microhardness were measured. Films were amorphous or polycrystalline in dependence on deposition temperature (from RT to 600°C). Antibacterial properties were tested using Escherichia coli and Bacillus subtilis cells. The antibacterial efficacy changed with silver doping from 4% to 100%. Cytotoxicity was studied by a direct contact test. Depending on doping and crystallinity the films were either non-toxic or mildly toxic.
► Silver doped hydroxyapatite layers synthetized by laser deposition ► Study of antibacterial properties (Gram positive and Gram negative bacteria) ► From cytotoxicity tests it follows that doped amorphous HA layers are mildly toxic.
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