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In the present study, the influence of disperse systems on Raman scattering was investigated. How an increasing particle concentration weakens the quantitative signal of the Raman spectrum is shown. Furthermore, the change in the position of the optimal measurement point in the fluid was considered in detail. Additional transmission measurements can be used to derive a simple and robust correction method that allows the actual concentration of the continuous phase to be determined with a standard deviation of 2.6%. [ABSTRACT FROM AUTHOR]

Background. Molecular structures combining a phosphorus-containing counterpart and non-polar radicals are employed in design of pro-drugs as structural and functional groups necessary for transportation of drugs through cellular barriers. It is assumed that the carrier itself does not exhibit biological activity. However, the “organic phosphate – alkyl radical” complex may possess its own metabolic and pharmacological properties even in the absence of a drug moiety.The aim. To study the effect of fluorinated alkyl phosphates on the growth of bacterial test cultures in an agar medium and to identify conjugated metabolic markers using UV/visible spectroscopy.Materials and methods. The effect of six organyl phosphates on the growth of five types of bacteria under aerobic conditions was evaluated by the method of wells in an agar medium. For solutions containing cell metabolites of Pseudomonas aeruginosa, the absorption spectra were recorded at 250–280 nm. The principal component analysis (PCA) was used for multivariate comparative analysis of the spectra. Results. The studied organyl phosphates bearing the ethyl and propyl radicals are potential temporary carriers of the drug moiety, since they are capable of penetrating through cellular barriers. However, the fluorinated compounds exhibit bactericidal properties, the degree of which depends on the arrangement of fluorine atoms in the radical. The most active compounds are those exhaustively halogenated at the terminal carbon atom of the ethyl radical (-СН2-СF3), while non-fluorinated organyl phosphate is the least active. UV/visible spectra of P. aeruginosa cultivation products, according to PCA data, contain patterns reflecting the metabolic effects mediated by these structural features of the radicals.Conclusion. In terms of practical application of the studied compounds, the activity of a proantibiotic based on organyl phosphate with a non-fluorinated ethyl(propyl) radical will be determined only by the specificity of the drug moiety. Exactly the same molecule, but exhaustively fluorinated at the terminal carbon atom of the alkyl radical, is likely to be characterized by lower specificity and higher activity under the additive (or synergistic) action of metabolically active groups.

Spectroscopic data, depending on an experimentally controllable variable, contains a wealth of information for researchers. However, complex spectra with overlapping peaks and multiple transitions complicate its straightforward interpretation and often the full contained information cannot be extracted. Here, the Spectram toolbox for MATLAB® and GNU Octave is described which was developed to analyse such data by a method based on singular value decomposition (SVD) and transition model coupled recombination. The method employs user-defined transition models, which depend on the control variable and are often known, or empirical descriptions of the transitions, which often can be guessed, to deconvolute such data. The outcome are the spectral components associated to the transitions and the model parameters. Both can be directly interpreted in terms of their physical meaning. Spectram can be applied to any desired spectroscopic technique and gives full freedom in the choice of the applied models, making it highly reusable. Funding statement: Funding by the European Union’s Horizon 2020 research and innovation program under a Marie Skłodowska-Curie Grant (Agreement No. 705857) is acknowledged.

Cellulose utilization at its full potential often requires its dissolution which is challenging. Aqueous NaOH is the solvent of choice due to the rapid, non-toxic, low cost and environmentally friendly dissolution process. However, there are several limitations, such as the required low temperature and cellulose´s moderately low degree of polymerization and concentration. Moreover, there is a tendency for gelation of semidilute solutions with time and temperature. The addition of ZnO aids cellulose dissolution and hinders self-aggregation in the NaOH solution; however, the exact role of ZnO has remained as an open question. In this work, we studied cellulose dissolution in the aqueous NaOH–ZnO system as well as the reactivity of the dissolved cellulose by oxidation with 4-AcNH-TEMPO+ (TEMPO+). Based on Raman spectroscopic studies and the TEMPO+-reactivities, we propose a new structure for cellulose dissolved in aqueous NaOH–ZnO. [ABSTRACT FROM AUTHOR]

To form many bulk chemicals, gaseous substances must be mixed and reacted with a continuous liquid phase. In this research work, we systematically investigate to what extent the formation of a side product in a fast competing consecutive reaction can be influenced by the time scales of mixing. For this purpose, a Taylor bubble experiment is used, in which the time scales of mixing can be varied systematically and reproducibly. It is shown, that the mixing in the wake of a bubble is of great importance for the formation of by‐products. [ABSTRACT FROM AUTHOR]

Spectroscopic data, depending on an experimentally controllable variable, contains a wealth of information for researchers. However, complex spectra with overlapping peaks and multiple transitions complicate its straightforward interpretation and often the full contained information cannot be extracted. Here, the Spectram toolbox for MATLAB® and GNU Octave is described which was developed to analyse such data by a method based on singular value decomposition (SVD) and transition model coupled recombination. The method employs user-defined transition models, which depend on the control variable and are often known, or empirical descriptions of the transitions, which often can be guessed, to deconvolute such data. The outcome are the spectral components associated to the transitions and the model parameters. Both can be directly interpreted in terms of their physical meaning. Spectram can be applied to any desired spectroscopic technique and gives full freedom in the choice of the applied models, making it highly reusable. [ABSTRACT FROM AUTHOR]

The combustion process of stoichiometric aluminium/copper(II)oxide thermite was experimentally investigated in an optical bomb under inert atmosphere (N2) and ambient pressure. The reaction zone was monitored with UV/VIS emission spectroscopy and a colour high‐speed camera. The emission spectra were analysed by modelling of the background radiation and the characteristic emission of all molecular emitters in the reaction of Al/CuO. Based on this, the particles′ surface and gas phase temperature, the emissivity and the radiation of energy was determined by a non‐linear least squares fit between experimental and modelled spectra. This work presents the first modelling of the diatomic band system of Cu2 and CuO. The results obtained can help to understand the underlying processes in thermite combustion and the influence of radiation processes in modelling the combustion of thermite mixtures. [ABSTRACT FROM AUTHOR]

Non-covalent interactions of metallo compounds with DNA range from the simple, unspecific electrostatic binding of a positively charged metal complex to the sequence-selective recognition of DNA binding sites due to shape, size, symmetry and hydrogen bonding complementarity of a rationally designed system. Metal complexes that recognize and target specific DNA sequences or particular structures are of considerable interest as therapeutics, diagnostics or structural probes. To gain molecular level insight into DNA–metal complex interactions, binding studies are carried out in cell-free systems using isolated DNA or short oligonucleotides. For this, a powerful toolbox of complementary spectroscopic and biophysical techniques is available. This review focuses on the most frequently applied spectroscopic methods; UV/Vis, CD, LD, fluorescence emission and NMR spectroscopy and is aimed at giving the reader an overview of the qualitative and/or quantitative information that can be obtained. After a short introduction into DNA structures and non-covalent metal complex–DNA interactions, each spectroscopic method will be discussed. In the last section a few selected studies will be described as illustrative examples for the potential of the various spectroscopic methods.

The content of ferulic acid in sugar beet pulp was determined by reverse phase high-pressure liquid chromatography (HPLC) and UV/VIS-spectroscopy. The acid extracts of pectin carrying feruloyl groups were prepared for analysis. To release ferulic acid from pectin the hydrolysis in alkaline medium (pH = 12.5) was performed. Both non-hydrolysed and hydrolysed extracts were measured by UV/VIS-spectroscopy after pH adjustment to the value of 10. The absorbance maximum was observed at 372 nm (ester of ferulic acid) for non-hydrolysed extracts and at 345 nm (sodium ferulate) for hydrolysed extracts. The HPLC estimation of ferulic acid was made in hydrolysed extracts only. The content of ferulic acid in sugar beet pulp was in the range of 0.3-0.9% (m/m). The data obtained by application of the particular methods to one set of samples were statistically compared. The results of all methods were in good agreement with each other\

Abstract: Poly(acrylamide) [poly(AAm)] and poly(N-isopropyl-acrylamide) [poly(NIPAAm)] based gel films containing Au nanoparticles (d =14±2.5nm) were synthesized. Monomers and cross-linker were added to a gold nanodispersion, and after the addition of the initiator, polymer films were prepared on the surface of an interdigital microelectrode by photopolymerization. In the course of the syntheses the gold concentration of the films was constant (10.8μg/cm2) and the volume fraction of Au nanoparticles (ϕ Au) in the polymer gel films varied in the range of 0.58–85.3%. Poly(AAm)-based films swell when the temperature increases: due to a temperature shift of 15°C the Au plasmon absorption maximum at λ =∼532nm was shifted towards shorter wavelengths by 16.6nm (blue shift) through the swelling of the polymer gel film. In the case of poly(NIPAAm) the temperature-induced shrinking resulted in a red shift, namely the maximum was shifted by 18.07nm by a temperature shift of 15°C. In the case of both composites, the electric conductivity of the samples was shown to increase with increasing Au particle concentration. In the case of the poly(AAm)-based composite containing ϕ Au =0.85 gold the resistance of the film spread on the surface of the electrode was 0.16MΩ at 25°C and 0.66MΩ at 50°C, i.e. the conductivity of the sample decreased with increasing temperature. The opposite effect is observed in the case of the poly(NIPAAm)-based composite: as temperature is raised, the resistance of the composite abruptly drops at the point of collapse of the NIPAAm gel (it is 0.28MΩ at 32°C and only 0.021MΩ at 35°C). This thermosensitive effect was detectable only at sufficiently high Au contents (ϕ Au =0.85) in both gels. [Copyright &y& Elsevier]

The use of UV/VIS-spectroscopy for water quality measurements is based on the solution of the correlation between the surrogate parameter absorbance and the resulting equivalence parameters. The coherence of absorbance and equivalence parameters (CODtot, CODsol, TSS) is solved in this paper with different regression methods. The correlation of absorbance and concentrations are analysed based on linear regression methods, model tree regressions, multivariate regression methods and support vector machines using sequential minimal optimisation algorithm. For this purpose the regression methods are calibrated on three 24hours measurement campaigns of a combined sewer measurement station situated in the combined sewer overflow chamber in Graz (Austria). The online measurement station has been conveying data for more than 2⅛ years up to now. Finally, the load calculation based on the different regression methods and its comparison demonstrate that an apparently complex model does not inevitably lead to accurate concentration values due to possible model overfitting. Hence, the paper points out the possibilities and the drawbacks of spectroscopy measuring in sewers and the arising concentration values. [ABSTRACT FROM AUTHOR]

The absorbance in the 190–500 nm range of oxidized lignin-free xylan isolated from unbleached and ozone-bleached hardwood kraft pulps as well as monocarboxyl cellulose in NaOH solution was examined by UV/VIS-spectroscopy and SEC employing multi-wave UV-detection. The first derivative of UV-spectra has been shown to be more useful to investigate the chromophore composition. The chromophore composition of oxypolysaccharides was as follows: carboxyl and carbonyl groups absorbing at 200–220 and 270–290 nm, respectively, heteroaromatics of furan- and pyron-type absorbing additionally at 230–250 and 290–320 nm as well as conjugated heteroaromatics absorbing above 300 nm with maximums at 350–370 and 430–450 nm due to the charge-transfer complexes. Problems regarding the attribution of absorbance to lignin- and heteroaromatics-derived chromophores are discussed. Conjugated heteroaromatic compounds, non-uniformly distributed over MWD, are supposed to be the source for the gel-fraction and contributors to the colour of oxidized polysaccharides. [Copyright &y& Elsevier]

The caa 3 -oxidase from Thermus thermophilus has been studied with a combined electrochemical, UV/VIS and Fourier-transform infrared (FT-IR) spectroscopic approach. In this oxidase the electron donor, cytochrome c , is covalently bound to subunit II of the cytochrome c oxidase. Oxidative electrochemical redox titrations in the visible spectral range yielded a midpoint potential of -0.01 ± 0.01 V (vs. Ag/AgCl/3m KCl, 0.218 V vs. SHE′) for the heme c . This potential differs for about 50 mV from the midpoint potential of isolated cytochrome c , indicating the possible shifts of the cytochrome c potential when bound to cytochrome c oxidase. For the signals where the hemes a and a 3 contribute, three potentials, = -0.075 V ± 0.01 V, E m2 = 0.04 V ± 0.01 V and E m3 = 0.17 V ± 0.02 V (0.133, 0.248 and 0.378 V vs. SHE′, respectively) could be obtained. Potential titrations after addition of the inhibitor cyanide yielded a midpoint potential of -0.22 V ± 0.01 V for heme a 3 -CN– and of E m2 = 0.00 V ± 0.02 V and E m3 = 0.17 V ± 0.02 V for heme a (-0.012 V, 0.208 V and 0.378 V vs. SHE′, respectively). The three phases of the potential-dependent development of the difference signals can be attributed to the cooperativity between the hemes a , a 3 and the CuB center, showing typical behavior for cytochrome c oxidases. A stronger cooperativity of CuB is discussed to reflect the modulation of the enzyme to the different key residues involved in proton pumping. We thus studied the FT-IR spectroscopic properties of this enzyme to identify alternative protonatable sites. The vibrational modes of a protonated aspartic or glutamic acid at 1714 cm-1 concomitant with the reduced form of the protein can be identified, a mode which is not present for other cytochrome c oxidases.... [ABSTRACT FROM AUTHOR]

A series of new hybrid peralkylated-amine-guanidine ligands based on a 1,3-propanediamine backbone and their Cu-O 2 chemistry is reported. The copper(I) complexes react readily with O 2 at low temperatures in aprotic solvents with weakly coordinating anions to form exclusively bis(μ-oxo) dicopper species ( O ). Variation of the substituents on each side of the hybrid bidentate ligand highlights that less sterically demanding amine and guanidine substituents increase not only the thermal stability of the formed O cores but enhance inner-sphere phenolate hydroxylation pathways. TD-DFT analysis on selected guanidine-amine O species suggest that the additional visible feature observed is a guanidine π*→ Cu 2 O 2 LMCT, which appears along with the classic oxo-ζ u *→Cu(III) and π ζ *→ Cu(III) LMCT transitions.