Evaluation of Oxidative Species in Gaseous and Liquid Phase Generated by Mini-Gliding Arc Discharge

Plasma Chemistry and Plasma Processing - The gliding arc discharge plasma reactors are known as a source of non-equilibrium plasma at atmospheric pressure. In the present study, generation of...     

Stereoselective Michael Addition of Carbonyl Compounds to ( E )-β-Nitrostyrene Catalysed by N -Toluensulfonyl-l -proline Amide in Ionic Liquids

N-Toluensulfonyl-l-prolin amide was tested as catalyst in the enantioselective Michael addition of carbonyl compounds to (E)-β-nitrostyrene in nine ionic liquids under different reaction conditions. The reaction rates and enantioselectivities were strongly dependent on the ionic liquids. Change of enantioselectivity was observed too and it is attributed to both the cation and the anion of ionic liquid. The best yields (up to 98%) and enantioselectivity (70% ee) of product were obtained in a basic ionic liquid [bmim]BF₄ at room temperature.     

Direct determination of celiprolol in human urine using on-line coupled ITP-CZE method with fiber-based DAD

The present work illustrated possibilities of column-coupling electrophoresis combined with DAD for the direct quantitative determination of trace drug (celiprolol, CEL) in clinical human urine samples. ITP, on-line coupled with CZE, served as an ideal injection technique (high sample load capacity, narrow and sharp drug zone). Moreover, the ITP provided an effective on-line sample pretreatment (preseparation, purification and preconcentration of the drug) producing analyte zone suitable for its direct detection and quantitation in CZE stage. Spectral DAD in comparison with single wavelength ultraviolet detection enhanced value of analytical information (i) verifying purity (i.e., spectral homogeneity) of drug zone (according to differences in spectrum profiles when compared tested and reference drug spectra) and (ii) indicating zones/peaks with spectra similar to the drug spectrum (potential structurally related metabolites). The characterization of trace analyte signals superposed on the baseline noise was more definite thanks to the application of background correction and smoothing procedure to the raw DAD spectra (producing relevant spectral response). The proposed ITP-CZE-DAD method was characterized by favorable performance parameters for CEL in urine matrices {e.g., the lower limit of quantification was 9.7 ng/mL, RSD and relative error of the determinations were lower than 3% (precision) and 1% (accuracy), respectively, analyte peak exhibited spectral homogeneity (reflecting separation selectivity), separation efficiency was 84,500 theoretical plates} and successfully applied in a trial pharmacokinetic study of CEL.     

Effect of different Fe(III) compounds on photosynthetic electron transport in spinach chloroplasts and on iron accumulation in maize plants

Synthesis and spectral characteristics of [Fe(nia)₃Cl₃] and [Fe(nia)₃(H₂O)₂](ClO₄)₃ are described. The effect of these compounds as well as of FeCl₃·6H₂O on photosynthetic electron transport in spinach chloroplasts was investigated using EPR spectroscopy. It was found that due to the interaction of these compounds with tyrosine radicals situated at the 161^st position in D₁ (Tyr_Z) and D₂ (Tyr_D) proteins located at the donor side of photosystem (PS) II, electron transport between the photosynthetic centres PS II and PS I was interrupted. In addition, the treatment with [Fe(nia)₃(H₂O)₂](ClO₄)₃ resulted in a release of Mn(II) from the oxygen evolving complex situated on the donor side of PS II. Moreover, the effect of the Fe(III) compounds studied on some production characteristics of hydroponically cultivated maize plants and on Fe accumulation in plant organs was investigated. In general, the production characteristic most inhibited by the presence of Fe(III) compounds was the leaf dry mass and [Fe(nia)₃(H₂O)₂](ClO₄)₃ was found to be the most effective compound. The highest Fe amount was accumulated in the roots, and the leaves treated with Fe(III) compounds contained more Fe than the stems. The treatment with FeCl₃·6H₂O caused the most effective translocation of Fe into the shoots. Comparing the effect of nicotinamide complexes, [Fe(nia)₃(H₂O)₂](ClO₄)₃ was found to facilitate the translocation of Fe into the shoots more effectively than [Fe(nia)₃Cl₃]. This could be connected with the different structure of these complexes. [Fe(nia)₃(H₂O)₂](ClO₄)₃ has ionic structure and, in addition, coordinated H₂O molecules can be easily substituted by other ligands. Dedicated to Professor Milan Melník on the occasion of his 70th birthday.     

Capillary electrophoresis-mass spectrometry for intact protein analysis: Pharmaceutical and biomedical applications (2018–March 2023)

Capillary electrophoresis is recognized as a valued separation technique for its high separation efficiency, low sample consumption, good economic and ecological aspects, reproducibility, and complementarity to traditional liquid chromatography techniques. Capillary electrophoresis experiments are generally performed utilizing optical detection, such as ultraviolet or fluorescence detectors. However, in order to provide structural information, capillary electrophoresis hyphenated to highly sensitive and selective mass spectrometry has been developed to overcome the limitations of optical detections. Capillary electrophoresis-mass spectrometry is increasingly popular in protein analysis, including biopharmaceutical and biomedical research. It is frequently applied for the determination of physicochemical and biochemical parameters of proteins, offers excellent performance for in-depth characterizations of biopharmaceuticals at various levels of analysis, and has been also already proven as a promising tool in biomarker discovery. In this review, we focus on the possibilities and limitations of capillary electrophoresis-mass spectrometry for protein analysis at their intact level. Various capillary electrophoresis modes and capillary electrophoresis-mass spectrometry interfaces, as well as approaches to prevent protein adsorption and to enhance sample loading capacity, are discussed and the recent (2018–March 2023) developments and applications in the field of biopharmaceutical and biomedical analysis are summarized.     

Stochastic modelling and simulation of a kidney transplant waiting list

We created a dynamic stochastic model to evaluate the performance of a kidney transplantation system. Our model is applicable in the context of a small country where the legislation requires that a kidney from a deceased donor should be used whenever available. Using a systematic design of simulation experiments, we performed a complex simulation study based on real medical data to explore the impact of factors representing different rates of deceased kidneys harvesting, the proportion of patients with a willing living donor and different allocation policies. On the basis of careful statistical analysis carried out by two different statistical methodologies, ANOVA and bootstrap, we draw some important conclusions about the effects of these factors and recommendations for the medical community. The results of the study clearly demonstrate that in addition to increasing the numbers of kidney donors, deceased as well as living, the introduction of a kidney exchange program leads to further expansion of the numbers of donations and to shortening of waiting time for transplantation. Moreover, we observed that the largest and most counter-intuitive effect on waiting time and transplantation probability was obtained by replacing the currently implemented first-come-first-transplanted allocation policy to a policy that prioritizes the most vulnerable group of patients. This change has led to shortening the waiting time of these patients by enormous 28 months on average while leaving the waiting time of other patients practically the same.

     

On max-min linear inequalities and Coalitional Resource Games with sharable resources

In a Coalitional Resource Game (CRG for brief), agents form coalitions to pool their resources in order to achieve certain goals, requiring the expenditure of these resources. A particular coalition is said to be successful, if the common resources of its members enable to achieve a set of goals that satisfies all members of the coalition. It is known that when resources are consumable it is NP-complete to decide whether a given coalition is successful. In this paper, we show a connection of CRGs with sharable resources and max-min linear systems of inequalities. This correspondence leads to polynomial algorithms for checking whether a given CRG admits a successful coalition and for several other problems whose counterparts for CRGs with consumable resources are hard. On the other hand, we prove that some problems concerning the structure of successful coalitions are hard also in the case of sharable resources.