The aim of this study was the evaluation of (Ca10-xAgx)(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic ...bacteria has emerged in the recent years as a major public health problem worldwide. In this paper, we report a comparison of the antimicrobial activity of low concentrations silver-doped hydroxyapatite nanoparticles. The silver-doped nanocrystalline hydroxyapatite powder was synthesized at 100°C in deionised water. The as-prepared Ag:Hap nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and FT-Raman spectroscopy. X-ray diffraction (XRD) studies demonstrate that powders obtained by coprecipitation at 100°C exhibit the apatite characteristics with good crystal structure, without any new phase or impurities found. FT-IR and FT-Raman spectroscopy revealed the presence of the various vibrational modes corresponding to phosphates and hydroxyl groups and the absence of any band characteristic to silver. The specific microbiological assays demonstrated that Ag:HAp-NPs exhibited antimicrobial features, but interacted differently with the Gram-positive, Gram-negative bacterial and fungal tested strains.
Temperature dependences of pressure-broadened half-width and pressure-induced shift coefficients along with accurate positions and intensities have been determined for transitions in the 2←0 band of ...12C16O from analyzing high-resolution and high signal-to-noise spectra recorded with two different Fourier transform spectrometers. A total of 28 spectra, 16 self-broadened and 12 air-broadened, recorded using high-purity (≥99.5% 12C-enriched) CO samples and CO diluted with dry air (research grade) at different temperatures and pressures, were analyzed simultaneously to maximize the accuracy of the retrieved parameters. The sample temperatures ranged from 150 to 298K and the total pressures varied between 5 and 700Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to adjust the rovibrational constants (G, B, D, etc.) and intensity parameters (including Herman–Wallis coefficients), rather than determining individual line positions and intensities. Self- and air-broadened Lorentz half-width coefficients, their temperature dependence exponents, self- and air-pressure-induced shift coefficients, their temperature dependences, self- and air- line mixing coefficients, their temperature dependences and speed dependence have been retrieved from the analysis. Speed-dependent line shapes with line mixing employing off-diagonal relaxation matrix element formalism were needed to minimize the fit residuals. This study presents a precise and complete set of spectral line parameters that consistently reproduce the spectrum of carbon monoxide over terrestrial atmospheric conditions.
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•A constrained multispectrum analysis of 9 spectra of CO2 was performed.•Retrieved line parameters for the 12201←03301, 11101←10002, 12201←11102 bands of CO2.•Analyzed line mixing ...effects for 12201←03301, 11101←10002, 12201←11102 Q-branches.
Pure CO2 spectra recorded at room temperature and different pressures (0.2–140Torr) have been analyzed with the help of a fitting routine that takes into account asymmetries arising in the spectral lines due to pressure induced effects such as line mixing. The fitting procedure used in this study allows one to adjust the ro-vibrational constants for the band rather than fitting for individual line parameters. These constrained parameters greatly reduce the measurement uncertainties and allow us to observe the behavior of the weak lines corresponding to high J quantum numbers. We have also calculated line mixing parameters using approximations based on exponential nature of the energy difference between ground and upper vibrational states involved in the ro-vibrational band transitions. The calculated results show good agreement when compared with the experimentally determined parameters.
Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the ...present study, the Ag:HAp and the corresponding Ag:HAp + D3 thin films (~200 nm) coating were obtained by vacuum deposition method on Ti substrate. The obtained samples were exposed to different UV irradiation times, in order to investigate the UV light action upon thin films, before considering this method for the thin film’s decontamination. The effects of UV irradiation upon Ag:Hap + D3 are presented for the first time in the literature, marking a turning point for understanding the effect of UV light on composite biomaterial thin films. The UV irradiation induced an increase in the initial stages of surface roughness of Ag:HAp thin film, correlated with the modifications of XPS and FTIR signals. The characteristics of thin films measured by AFM (RMS) analysis corroborated with XPS and FTIR investigation highlighted a process of recovery of the thin film’s properties (e.g., RMS), suggesting a possible adaptation to UV irradiation. This process has been a stage to a more complicated UVA rapid degradation process. The antifungal assays demonstrated that all the investigated samples exhibited antifungal properties. Moreover, the cytotoxicity assays revealed that the HeLa cells morphology did not show any alterations after 24 h of incubation with the Ag:HAp and Ag:HAp + D3 thin films.
Due to the importance of methane as a trace atmospheric gas and a greenhouse gas, we have carried out a precise line-shape study to obtain the CH4–CH4 and CH4–air half-width coefficients, CH4–CH4 and ...CH4–air shift coefficients and off-diagonal relaxation matrix element coefficients for methane transitions in the spectral range known as the “methane Octad”. In addition, the associated temperature dependences of these coefficients have been measured in the 4300–4500cm−1 region of the Octad. The high signal to noise ratio spectra of pure methane and of dilute mixtures of methane in dry air with high resolution have been recorded at temperatures from 148K to room temperature using the Bruker IFS 125 HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California. The analysis of spectra was done using a multispectrum non-linear least-squares curve fitting technique. Theoretical calculations have been performed and the results are compared with the previously published line positions, intensities and with the line parameters available in the GEISA and HITRAN2012 databases.
Display omitted Section of the spectra of pure methane and methane broadened by air in the spectral range of the υ3+υ4. The bottom panels show the fit residuals obtained using the Voigt and quadratic speed-dependent Voigt profiles including line mixing.
•Self- and air–half-width, pressure-shift, line mixing coefficients are reported.•The temperature dependence of CH4–CH4 and CH4–air half-width, CH4–CH4 and CH4–air shift parameters in the υ3+υ4 band of methane were presented.•The temperature dependencies of self-, air-broadened line parameters are presented.•The quadratic SDV profile including line mixing was used in the retrievals.
We report revisited experimentally retrieved and theoretically calculated He-broadened Lorentz half-width coefficients and He- pressure-shift coefficients of 45 carbon monoxide transitions in the 1←0 ...band. The spectra analyzed in this study were recorded over a range of temperatures between 79 and 296K. The He-broadened line parameters and their temperature dependences were retrieved using a multispectrum nonlinear least squares analysis program. The line shape models used in this study include Voigt, speed dependent Voigt, Rautian (to take into account confinement narrowing) and Rautian with speed dependence, all with an asymmetric component added to account for weak line mixing effects. We were unable to retrieve the temperature dependence of line mixing coefficients. A classical method was used to determine the He-narrowing parameters while quantum dynamical calculations were performed to determine He-broadening and He-pressure shifts coefficients at different temperatures. The line mixing coefficients were also derived from the exponential power gap law and the energy corrected sudden approximation. The current measurements and theoretical results are compared with other published results, where appropriate.
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•Temperature dependences of He-broadened widths and shifts in the fundamental of CO.•Theoretical calculations of He-broadened widths and shifts over a range of temperatures.•CO–He line mixing coefficients in the 1←0 band.
We report measurement results for line positions, intensities, half-width, and pressure-induced shift coefficients and line mixing coefficients for N
2
O broadened by air in the ν
3
band. The high ...signal-to-noise ratio spectra have been recorded at high resolution using the McMath–Pierce Fourier transform spectrometer formerly located at the National Solar Observatory on Kitt Peak, Ariz., USA. The spectra were analyzed using a multispectrum nonlinear least-squares curve-fitting technique employing the speed-dependent Voigt profile with a Rosenkranz (weak) line mixing component. The speed dependence parameters were calculated as suggested in the study of Kochanov (J. Quant. Spectrosc. Radiat. Transf. 189, 18 (2017). doi: 10.1016/j.jqsrt.2016.11.007 ). Several comparisons have been performed between the retrieved parameters and previously published results. For |m| ≤ 40, our results for line positions, broadening, and line mixing coefficients agree best with the results of Loos et al. (J. Quant. Spectrosc. Radiat. Transf. 151, 300 (2015). doi: 10.1016/j.jqsrt.2014.10.008 ). Also, we compared the obtained line positions and intensities with the corresponding values in HITRAN2016 and GEISA-2015 databases. No significant or systematic differences were noticed. The precision of our line positions was estimated to be 3 × 10
−5
cm
−1
. The reported line positions, intensities, and air-broadening coefficients are accurate to better than 2%. The accuracy of air-pressure-induced line shifts and line mixing coefficients is better than 5%. The line mixing coefficients and air-broadening coefficients were also calculated using the exponential power gap scaling law, and these calculated values were found to be in good agreement with the experimental results.
We report measurement results for line positions, intensities, half-width, and pressure-induced shift coefficients and line mixing coefficients for N.sub.2O broadened by air in the v.sub.3 band. The ...high signal-to-noise ratio spectra have been recorded at high resolution using the McMath-Pierce Fourier transform spectrometer formerly located at the National Solar Observatory on Kitt Peak, Ariz., USA. The spectra were analyzed using a multispectrum nonlinear least-squares curve-fitting technique employing the speed-dependent Voigt profile with a Rosenkranz (weak) line mixing component. The speed dependence parameters were calculated as suggested in the study of Kochanov (J. Quant. Spectrosc. Radiat. Transf. 189, 18 (2017). doi:10.1016/j.jqsrt.2016.11.007). Several comparisons have been performed between the retrieved parameters and previously published results. For absolute value of (m) less than or equal to 40, our results for line positions, broadening, and line mixing coefficients agree best with the results of Loos et al. (J. Quant. Spectrosc. Radiat. Transf. 151, 300 (2015). doi:10.1016/j.jqsrt.2014.10.008). Also, we compared the obtained line positions and intensities with the corresponding values in HITRAN2016 and GEISA-2015 databases. No significant or systematic differences were noticed. The precision of our line positions was estimated to be 3 x 10.sup.-5 cm.sup.-1. The reported line positions, intensities, and air-broadening coefficients are accurate to better than 2%. The accuracy of air-pressure- induced line shifts and line mixing coefficients is better than 5%. The line mixing coefficients and air-broadening coefficients were also calculated using the exponential power gap scaling law, and these calculated values were found to be in good agreement with the experimental results.
Two atmospheric trace gases, namely methane and carbon monoxide have been considered in this study. Fourier transform absorption spectra of the 2-0 band of 12C16O mixed with CO2 have been recorded at ...total pressures from 156 to 1212 hPa and at 4 different temperatures between 240 K and 283 K. CO2 pressure-induced line broadening and line shift coefficients, and the associated temperature dependence have been measured in an multi-spectrum non-linear least squares analysis using Voigt profiles with an asymmetric profile due to line mixing. The measured CO2-broadening and CO2-shift parameters were compared with theoretical values, calculated by collaborators. In addition, the CO2-broadening and shift coefficients have been calculated for individual temperatures using the Exponential Power Gap (EPG) semi-empirical method. We also discuss the retrieved line shape parameters for Methane transitions in the spectral range known as the Methane Octad. We used high resolution spectra of pure methane and of dilute mixtures of methane in dry air, recorded with high signal to noise ratio at temperatures between 148 K and room temperature using the Bruker IFS 125 HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California. Theoretical calculations for line parameters have been performed and the results are compared with the previously published values and with the line parameters available in the GEISA2015 1 and HITRAN2012 2 databases.
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