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Emerging Contaminants in Sewage Sludge: Analysis and Their Removal by Pyrolysis
Hušek, Matěj
2024 - anglický
The study continues with flame retardants (e.g., phosphorus-based or brominated) present in sludge, which may pose a hazard to nature and human health3,4. There is a lack of information on their pyrolysis removal and occurrence in the sludge in the Czech Republic.
Klíčová slova:
sewage sludge; pyrolysis; PFAS; flame retardants
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Emerging Contaminants in Sewage Sludge: Analysis and Their Removal by Pyrolysis
The study continues with flame retardants (e.g., phosphorus-based or brominated) present in sludge, which may pose a hazard to nature and human health3,4. There is a lack of information on their ...
Cholinium Based Ionic Liquids: Influence of Water as a Co-solvent on Their Physico-chemical Properties and Preliminary Results for Dissolution of Biopolymers
Souvenir Zafindrajaona, Mahasoa-Salina
2024 - anglický
Ionic liquids (ILs) are emerging as promising alternative solvents in the field of natural substance extraction, offering significant advantages over traditional solvents. Since the last decade, we notice the increasing use of greener solvent alternatives such as Natural Deep Eutectic Solvents (NaDES) or ILs for the extraction of highly valuable compounds from natural sources such as lignocellulose. During this presentation, the influence of water on heat capacity, density, speed of sound and TGA will be discussed and the preliminary results for lignin dissolution willbe presented.
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Cholinium Based Ionic Liquids: Influence of Water as a Co-solvent on Their Physico-chemical Properties and Preliminary Results for Dissolution of Biopolymers
Ionic liquids (ILs) are emerging as promising alternative solvents in the field of natural substance extraction, offering significant advantages over traditional solvents. Since the last decade, we ...
Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Macháček, Michael; Hračov, Stanislav
2024 - anglický
Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, critical onset wind speeds, and global dynamic response of a very low-tensioned line with simulated icing observed on similar real conductors. Due to the highly nonlinear mechanical behavior of such a flexible cable, we employed the Newmark integration method combined with the iterative Newton-Raphson method. We analyzed two numerical models of the overhead line loaded by the wind: one assuming nonlinearity only in the wind load, while retaining the linearity of the mechanical system itself, and the other representing a fully nonlinear system including geometrical nonlinearity. Our analysis revealed that the determined critical wind speeds for the onset of galloping are in relatively close ranges for both models. However, numerical simulations with the fully nonlinear system indicated significantly lower amplitudes of limit cycle oscillations, especially at higher wind speeds, compared to the linear model of the line. This underscores the necessity of using fully nonlinear models during the design stage of such low-tensioned aerial conductors.
Klíčová slova:
aerial bundled conductors; wind effects; galloping; limit cycle oscillation
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, ...
Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna; Bílek, Vojtěch; Haidl, Jan; Isoz, M.; Pivokonský, Martin
2024 - anglický
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
Klíčová slova:
flocculation tank; stirring; MRF; CFD; OpenFOAM
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Flow simulations approach for flocculation tanks
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and ...
Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment
Deri, M.; Vespi, M.; Giannarelli, S.; Hromadová, Magdaléna
2024 - anglický
The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate its redox mechanism. Both compounds show similar reduction behavior in the aprotic solvent that involves one electron transfer to the nitro group. The reduction of Pretomanid is more difficult and the stability of its nitro anion radical is much lower compared to the dimetridazole molecule.
Klíčová slova:
pretomanid; dimetridazole; cyclic voltammetry; reduction mechanism
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment
The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate ...
Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study
Koláčná, Lucie; Čubiňák, M.; Tobrman, T.; Ludvík, Jiří
2024 - anglický
The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk voltammetry in N,N-dimethylformamide. Due to multiple substitutions, the resulting potential gap represents the sum of all substituent effects. Different combinations of substituents can be used to achieve the desired properties of cyclohexene-pyrene derivatives. The electrochemical data presented in this contribution facilitate further tuning of properties of these molecules and systems to achieve features required in material chemistry just by means of chemical modification.
Klíčová slova:
pyrene; cyclohexene; conjugation
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study
The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk ...
Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Donkeng Dazie, Joel; Koláčná, Lucie; Urban, Jiří; Lamač, Martin; Ludvík, Jiří
2024 - anglický
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into furfuryl amines which are important precursors namely for pharmaceutical synthesis. First, FF and HMF underwent condensation reactions with various amines which were electrochemically monitored to optimize the process. The resulting Schiff bases were identified by NMR and subsequently electrochemically reduced in basic media. The vicinal diamine (aminopinacol) was the main product besides the expected furfuryl amines. This reaction is a contribution to green synthesis because it was performed electrochemically, in water, and without any metallic catalysts.
Klíčová slova:
furfural; 5-hydroxymethylfurfural; (di)amines
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into ...
Electrochemical Properties of Newly Synthesized Selaginpulvilins
Dostálová, L.; Sokolová, Romana; Schwarzová-Pecková, K.; Rýček, L.
2024 - anglický
The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins differing in the presence of a hydroxyl group in the media of 0.1 mol L-1 tetrabutylammonium hexafluorophosphate as supporting electrolyte in anhydrous acetonitrile. Both\ncompounds provided an oxidative signal in the positive region until +2.0 V.
Klíčová slova:
oxidation; cyclic voltammetry; selaginpulvilins
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Newly Synthesized Selaginpulvilins
The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins ...
3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
Vaněčková, Eva; Sebechlebská, Táňa; Kolivoška, Viliam
2024 - anglický
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The development of printable electrically conductive composite materials brought a revolution to electrochemistry, with 3D-printed electrodes being intensively studied from the viewpoint of\nanalytical performance and stability. However, it is often reported that 3D-printed electrodes have poor charge transfer characteristics, typically due to limited exposure of the electrically conductive phase at the composite surface to the surrounding solution. In this work, we devise and apply simple electrochemical activation procedures that lead to a significant improvement of charge transfer characteristics of 3D printed electrodes.
Klíčová slova:
three-dimensional printing; electrochemistry; electrodes
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The ...
Growth and Phosphorus Dynamics During Tolypothrix tenuis Cultivation – a Cyanobacterium of Biotechnological Potential
Mušálková, Petra
2024 - anglický
Here I investigated the course of biomass growth, phosphorus uptake and changes in intracellular phosphorus content in T. tenuis in a batch cultivation. Cultivation experiment was held in multiple bubble columns during a light regime (alternating light and dark periods 16 and 8h). Thanks to this experiment I was able to obtain a growth curve of T. tenuis. The decrease of phosphorus concentration in the medium was disproportionally faster\nthan biomass growth resulting in significant oscillations of phosphorus content in the biomass, which are typical characteristics for LPU. It was also observed, that after all phosphorus was removed from the medium, the algae growth continues over time, while obviously utilizing intracellular phosphorus reserves. These findings are valuable in course of using this cyanobacterium for efficient bioremediation of eutrophic water based on phosphorus removal by targeted algae cultivation.
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Growth and Phosphorus Dynamics During Tolypothrix tenuis Cultivation – a Cyanobacterium of Biotechnological Potential
Here I investigated the course of biomass growth, phosphorus uptake and changes in intracellular phosphorus content in T. tenuis in a batch cultivation. Cultivation experiment was held in multiple ...
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