To reduce data dimensionality and obtain an overview of the metabolite profile, a principal component analy- sis (PCA) was performed using data sets of individual samples obtained by the CE-TOFMS analysis. The PCA revealed that the two-dimensional plots of principal component 1 (PC1) and PC2 segregate the data cluster along the carbon sources (Fig. 2). The plots of PC1 axis for S. stipitis cultivated with glucose, xylose, and Glc- NAc was clearly separated and the plots of PC2 axis for the yeast cultivated with xylose was also separated from the other two groups. The proportion of variance, which shows how much of the original data is retained by each principal component, of PC1 and PC2 were 53.7% and 25.2%, respectively. Metabolites contributing to PC1 and 2 were then extracted based on their factor loading scores (Table 2 and Additional file 1: Table S1). Interest- ingly, 13 of the top 20 metabolites contributed to PC1 were nitrogen-containing compounds and include not only intermediates of the GlcNAc metabolic pathway but also amino acids, purines, and pyrimidines. In addition, phosphate, lactate, and citrate also highly contribute to PC1. Alternatively, pentose phosphate pathway compo- nents and uracil nucleotides (UMP, UDP, and UTP) were included in the metabolites contributing to PC2.
Since all nucleobases could be oxidized and/or reduced at polarized electrode surface, an alternative to all above mentioned methods for purines and pyrimidines is electrochemical detection. This method has some advantages over instrumental methods such as low cost, fast response, simplicity of construction and small dimensions of the devices, small testing sample volume and the most important – high sensitivity. Therefore, intensive efforts to apply different electrode materials for detection of nucleobases and DNA oxidation were undertaken. DNA oxidation results in DNA damage occurring as guanine oxidation peak. It is due to the fact that guanine is the most electrochemically active nitrogenous base.
sorption cross-sections differ by almost an order of mag- nitude in this region (Brion et al., 1998; Bogumil et al., 2003; Voigt et al., 2001). The low concentrations asso- ciated with short-lived species also result in weak absorp- tion. Bromine monoxide, BrO, exemplifies this case: al- though the absorption cross-section of BrO is large (about 1.5 × 10 −17 cm 2 molecule −1 at 338.5 nm) (Fleischmann et al., 2004), the tropospheric mixing ratio is typically only a few ppt (Honninger and Platt, 2002; Peters et al., 2005; Wag- ner et al., 2007; Mahajan et al., 2009). At a high atmospheric concentration of 10 pptv, the maximum absorption of BrO would be only about 4 × 10 −9 cm −1 , making it extremely difficult to measure. Even in the laboratory, low concen- trations of BrO are inevitable owing to its fast self-reaction (Fleischmann et al., 2004). Lastly, low gas concentrations are found also for substances with low vapour pressures; as a result, the ultraviolet spectra of many low volatility organic species of atmospheric interest have yet to be determined. This includes the large group of compounds with carbonyl or nitro functional groups, for which the n → π transition occurs in the near-ultraviolet.
The accuracy and precision of trace gas concentrations re- trieved from FTIR spectra depend on the stability of the light source during the measurement (Beer, 1992; Notholt et al., 1997) since intensity fluctuations can distort the fractional line depth in FTIR spectra (Keppel-Aleks et al., 2007). This distortion of the fractional line depth is due to an additional apodisation which results from the variable source intensity and distorts the instrumental line shape (ILS). Variations in the source brightness caused e.g. by clouds decrease the ac- curacy and precision, but cannot always be avoided. Thus, one aim of the NDACC and TCCON networks is to reduce the impact of source brightness fluctuations (SBFs) on FTIR spectra by applying a correction to the spectra following the measurements.
from conifer family plants of different genera. To achieve the goal, it is advisable to use coniferous trees, preferring growth conditions with different illumination. Spruce trees usually prefer shaded areas, pines grow in lighter areas, silver fir and cypress trees grow in areas with medium light. Research can be performed on the following plan: 1) select several species of spruce, fir, pine and cypress for comparison, 2) to conduct spectrophotometry of extracts from the leaves of these trees, 3) to determine the numerical indicators of the absorptionspectra of the extracts, 4) to compare the obtained numerical indicators and 5) to conclude on the priorities of absorption activity among conifers.
Our Swift monitoring program triggered two joint XMM-Newton, NuSTAR and HST observations on 11 and 21 December 2016 tar- geting NGC 3783, as its soft X-ray continuum was heavily obscured. Consequently, emission features, including the O vii radiative recombination continuum, stand out above the diminished continuum. We focus on the photoionized emission features in the De- cember 2016 RGS spectra, and compare them to the time-averaged RGS spectrum obtained in 2000–2001 when the continuum was unobscured. A two-phase photoionized plasma is required to account for the narrow emission features. These narrow emission features are weakly varying between 2000–2001 and December 2016. We also find a statistically significant broad emission component in the time-averaged RGS spectrum in 2000–2001. This broad emission component is significantly weaker in December 2016, suggesting that the obscurer is farther away than the X-ray broad-line region. In addition, by analyzing the archival high-resolution X-ray spectra, we find that nine photoionized absorption components with different ionization parameters and kinematics are required for the warm absorber in X-rays.
equivalent width to their value for 5063 Å, but for the 5156 Å fea- ture their result is approximately 50 per cent of that measured here (54 mÅ compared to 93 mÅ). Furthermore, they do not observe the line at 5193 Å, which we have detected, possibly due to the use of higher S/N spectra in the present paper. This was tested by degrad- ing theoretical spectra, calculated using the appropriate atmospheric parameters (from Gies & Lambert 1992) and Fe abundance for the line (taken from this work), indicating that the feature may have been unclear due to noise. Gies & Lambert considered two dif- ferent temperature estimates (17 390 and 14 860 K) and associated abundances. They state that their data are insufficient to distinguish between these temperatures. However, both temperature estimates are consistent with that found here (16 600 K). Proffitt & Quigley (2001) also investigated HD 51309, using IUE short wavelength prime (SWP) spectra to obtain an LTE abundance. Their value is much lower than the abundance derived by Gies & Lambert (1992) or that found here. As for HD 126341, this difference is believed to be due to the use of UV spectra rather than optical data, as their ef- fective temperature (16 570 K) and surface gravity (2.60 dex) agree well with our estimates.
All chemicals used in the synthesis of amides (1–12) were commercial products (Merck). The melting temperatures of synthesized compounds were determined on a Büchi 510 melting tempera- ture apparatus and, therefore, the values reported here are uncorrected. IR spectra were recorded in the range of 4000–400 cm –1 using the KBr pill on a
at the inner periphery of torus (n = 1-3). The schematic diagram is shown in Fig. 3. The emission is absorbed at the overlapping region, and emission decreases. The com- bination between the absorption at the HFS plasma of 3rd harmonic and the emission at the LFS plasma of 2nd har- monic results in the deep dip and the peak at 320 GHz.
The influence of the polarity of the solvent and hydrogen bonding on the electronic absorptionspectra of some previously synthesized substituted 1,2,4-triazoline-3-thiones was studied. The electronic absorptionspectra of inves- tigated compounds were recorded in the region from 190 nm to 360 nm in eight protic (water, ethylene glycol, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and tert-butanol) and five aprotic (acetonitrile, chloroform, dimethylsulfoxide, dimethylformamide and dioxane) solvents. Their absorption maxima appeared in the region be- tween 250 nm and 260 nm as a result of the electron transitions in the 1,2,4-triazoline-3-thione ring. Using the method of linear solvation energy relationships (LSER), the effects of solvent polarity and hydrogen bonding on the electronic absorptionspectra were interpreted. The results have shown that the influence of the aprotic solvents is more significant compared to that of the protic solvents.
Here, we present a novel analytical methodology for removing the contribution of thin overlayers (with thickness smaller than the information depth) from partial electron yield (PEY) NEXAFS spectra of two-layered systems (constituted by a substrate covered by an overlayer) to give the photo-absorption NEXAFS spectrum of the substrate. This method relies on the subtraction of the characteristic NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system of interest once the thickness of both overlayers is determined by XPS. Compared to the Òdouble normalizationÓ method occasionally used in the literature to correct for the signal from carbon contamination 37
system and pendant ring system are almost perpendicular to each other [dihedral angles = 75.57 (7) and 70.26 (10) , respectively]. In the extended structures, weak N—H O, C—H O and C—H interactions influence the centrosymmetric crystal packing. Density functional theory calculations were carried out using a 6–311 G++(d,p) basis set and the calculated structures are in good agreement with the crystal structures. The compounds were also characterized by UV–Vis absorption spectroscopy and the smallest (HOMO– LUMO) energy gaps of 2.89 and 2.54 eV indicate the enhanced non-linear responses (intermolecular charge transfers) of these systems.