Rivista e Edizione

Volume 16 (2023): Edizione 1 (January 2023)

Volume 15 (2022): Edizione 1 (January 2022)

Volume 14 (2021): Edizione 1 (January 2021)

Volume 13 (2020): Edizione 2 (October 2020)

Volume 13 (2020): Edizione 1 (April 2020)

Volume 12 (2019): Edizione 2 (October 2019)

Volume 12 (2019): Edizione 1 (April 2019)

Volume 11 (2018): Edizione 2 (October 2018)

Volume 11 (2018): Edizione 1 (April 2018)

Volume 10 (2017): Edizione 2 (December 2017)

Volume 10 (2017): Edizione 1 (April 2017)

Volume 9 (2016): Edizione 2 (October 2016)

Volume 9 (2016): Edizione 1 (April 2016)

Volume 8 (2015): Edizione 2 (October 2015)

Volume 8 (2015): Edizione 1 (April 2015)

Volume 7 (2014): Edizione 2 (October 2014)

Volume 7 (2014): Edizione 1 (April 2014)

Volume 6 (2013): Edizione 2 (October 2013)

Volume 6 (2013): Edizione 1 (April 2013)

Volume 5 (2012): Edizione 2 (October 2012)

Volume 5 (2012): Edizione 1 (April 2012)

Dettagli della rivista
Formato
Rivista
eISSN
1339-3065
Pubblicato per la prima volta
10 Dec 2012
Periodo di pubblicazione
2 volte all'anno
Lingue
Inglese

Cerca

Volume 15 (2022): Edizione 1 (January 2022)

Dettagli della rivista
Formato
Rivista
eISSN
1339-3065
Pubblicato per la prima volta
10 Dec 2012
Periodo di pubblicazione
2 volte all'anno
Lingue
Inglese

Cerca

14 Articoli
Accesso libero

Ceylon cinnamon and clove essential oils as promising free radical scavengers for skin care products

Pubblicato online: 24 Mar 2022
Pagine: 1 - 11

Astratto

Abstract

Due to adverse effects of free radicals on human skin and increasing consumer demand for natural ingredients, essential oils from basil, Ceylon cinnamon bark, clove, juniper, lavender, oregano, rosemary, tea tree, thyme, and ylang-ylang were assessed for their antiradical activity. The oils were evaluated in the concentration range of 5—0.1 mg·mL−1, in which the three reference synthetic antioxidants are most often added to mass-produced cosmetics. Among all examined samples, C. cinnamon oil at a concentration of 5 mg·mL−1 showed the strongest DPPH radical scavenging activity (0.41 mg·mL−1 IC50), followed by clove oil, BHA, α-tocopherol, and BHT (0.82, 0.84, 0.88 and 0.93 mg·mL−1 IC50), respectively. At the same concentration, the reduction power of C. cinnamon oil was higher (1.64 mg·mL−1 Trolox Eq.) than that of α-tocopherol and BHT (1.42 and 0.80 mmol·L−1 Trolox Eq., respectively) but lower than that of BHA (1.81 mmol·L–1 Trolox Eq.). Antiradical activity of the other eight essential oils was low or negligible. C. cinnamon oil and clove oil are promising antiradical agents for skin care but according to our GC-MS analysis, these oils contain 0.29 % of cinnamaldehyde, 0.03 % of linalool, 0.02 % of D-limonene, and 0.02 % of eugenol or 0.41 % of eugenol and 0.002 % of linalool, respectively, which are monitored contact allergens in cosmetics. Such a product is not be suitable for consumers allergic to these substances but for the vast majority of consumers it does not pose a risk in terms of allergic manifestations.

Parole chiave

  • bark oil
  • oil
  • free radical scavengers
  • skin care products
Accesso libero

On the energetics of radical adduct formation of OH with phenol analogs and aniline

Pubblicato online: 24 Mar 2022
Pagine: 12 - 17

Astratto

Abstract

Theoretical studies on aniline, phenol, benzenethiol, benzeneselenol, and their corresponding adducts with hydroxyl radical in possible positions on a hydrocarbon ring are presented. Bond dissociation enthalpies, related to radical scavenging of primary antioxidants, were calculated using the M06–2X/6–311+G** method. Calculated data were compared with available experimental data. Preferable homolytic bond dissociation of the presented molecules with OH through functional groups X—OH followed by the m–OH ones has been confirmed. The highest antioxidant activity among the investigated positions is predicted for benzeneselenol. Also, the formation of non-covalent van der Waals structures has been shown as important in radical scavenging.

Parole chiave

  • Bond Dissociation Enthalpy
  • DFT
  • hydroxyl radical
  • thermodynamics
Accesso libero

Binary mixtures containing imidazolium ionic liquids: properties measurement

Pubblicato online: 24 Mar 2022
Pagine: 18 - 28

Astratto

Abstract

Densities and transport properties (dynamic viscosity) of pure imidazolium ionic liquids 1-butyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium dicyanamide and their binary mixtures with water and ethanol were measured within the temperature range of 293.15—333.15 K. Obtained experimental data were used to calculate excess molar volume and viscosity deviation. For the chosen binary mixtures, variations of excess molar volume, partial molar volumes of mixture components and of the viscosity deviation with the binary mixture composition were correlated using the Redlich-Kister equation. In addition, variation of viscosity with the binary mixture composition and temperature was fitted using the Jouyban-Acree model.

Parole chiave

  • Imidazolium ionic liquids
  • density
  • dynamic viscosity
  • excess molar volume
  • viscosity deviation
  • Redlich-Kister equation
  • Jouyban-Acree equation
Accesso libero

Thermochemistry of antioxidant action of isoflavones and their deprotonated forms in aqueous solution: hydrogen or electron transfer?

Pubblicato online: 16 May 2022
Pagine: 29 - 35

Astratto

Abstract

Isoflavones possessing several weak acidic hydroxyl groups can undergo successive deprotonations in aqueous solutions. Therefore, their antioxidant properties cannot be ascribed only to the neutral forms but also to corresponding phenoxide anions. It was already confirmed that isoflavones prefer the formation of dianions in aqueous solution. For eight isoflavones and their preferred (poly)deprotonated forms, thermochemistry of hydrogen atom transfer and electron abstraction was studied in terms of corresponding reaction enthalpies, i.e., O—H bond dissociation enthalpies and ionization potentials. Our results clearly indicate that the increase in negative charge causes significant drop in ionization potential and bond dissociation enthalpy. On the other hand, proton affinities show the opposite trend. Thus, it is unfeasible to find a generally valid trend for dianions — corresponding reaction enthalpies strongly depend on the structure of isoflavone, especially on the number/positions of OH groups.

Parole chiave

  • Bond dissociation enthalpy
  • Consecutive deprotonations
  • Electron transfer
  • Phenoxide anion
Accesso libero

Pre-treatment of lignocellulosic materials by enzymatic mixture to enhance biogas production

Pubblicato online: 16 May 2022
Pagine: 36 - 43

Astratto

Abstract

The aim of this study was to evaluate the effect of an enzymatic mixture on the increase of biogas production from lignocellulosic materials as rapeseed straw, maize waste, and wheat straw. For efficient application of the enzymatic mixture, conditions of its use were optimized regarding 50 °C, pH 7 and an enzyme dose of 0.25 % w/v. Biogas potential test confirmed positive effect of the enzymatic mixture on anaerobic digestion of already thermally and alkali pre-treated lignocellulosic materials, as significantly higher biogas production was observed after the enzymatic mixture addition for all monitored substrates. Addition of the enzymatic mixture to the most used substrate at biogas plants — maize silage, had also positive effect on biogas production during the biogas potential test. This fact was not proven during long-term operations of the reactors as the values of total cumulative biogas productions for the whole monitored period from reactors for anaerobic digestion of maize silage with and without addition of enzymatic mixture did not differ significantly.

Parole chiave

  • anaerobic digestion
  • biomass
  • long-term operation
  • maize silage
  • methane
Accesso libero

Nanotextiles — materials suitable for respiratory tract protection but a source of nano- and microplastic particles in the environment

Pubblicato online: 16 May 2022
Pagine: 44 - 53

Astratto

Abstract

The paper deals with the formation of nanomaterials (nanoparticles and nanofibers) in the manufacture and use of respiratory protective equipment. It focuses mainly on processes leading to the release of nanoplastics into the workplace and the environment. Based on selected properties of materials used for the manufacture of protective equipment, their stability in the environment is revealed. The paper demonstrates the impact on the environment considering semichronic phytotoxicity of nanoplastics.

Parole chiave

  • nanofiber
  • electrospinning
  • nonwovens
  • nanoparticles
  • respirator
Accesso libero

Simultaneous detection of purine metabolites by membrane modified electrochemical sensors

Pubblicato online: 23 Aug 2022
Pagine: 54 - 60

Astratto

Abstract

Purine metabolites are important for metabolic and cellular processes. Deregulation of purinergic signaling leads to pathological accumulation of purine degradation products in extracellular fluids and indicates various diseases. In clinical diagnosis at early stages of related diseases, accurate detection of Uric acid and Xanthine is of high importance. Electrochemical methods are fast, simple, sensitive, more convenient, and cost-effective compared to other analytical methods used in purine metabolites signaling. Electrochemical sensors are able to detect more compounds simultaneously. Modification of a glassy carbon electrode sensor with external protective membranes was used in this study to avoid unwanted signal interferences from analyte matrices. Polyvinyl alcohol, Chitosan, and Nafion membranes were selected for sensor modification to compare the electro-neutral, positive and negative charged setting of the Xanthine and Uric acid detection. All three membrane modified sensors showed adequate stability in the phosphate buffer solution after 5 min of incubation and are thus suitable for simultaneous detection of purine metabolites. The best results in anodic peak current response values were observed using the Nafion membrane modified glassy carbon electrode sensor. The approach reported here can be useful for the detection of purine metabolites from various matrices at early stages of clinical diagnosis.

Parole chiave

  • electrochemistry
  • GCE
  • Chitosan
  • Nafion
  • purine metabolites
  • PVA
Accesso libero

The role of deep eutectic solvents in the production of cellulose nanomaterials from biomass

Pubblicato online: 23 Aug 2022
Pagine: 61 - 71

Astratto

Abstract

In recent years, the demand for environment-friendly products has been on an increasing trend among researchers and industry for sustainable development. Deep eutectic solvents are green solvents which, due to their properties (biodegradability, recyclability, low cost, availability, easy preparation, low toxicity, chemical and thermal stability), can be used in various fields such as polymer chemistry, which includes nanocellulose isolation and polysaccharides processing. Several studies have illustrated the effectiveness of using deep eutectic solvents instead of the conventional reaction system to produce and disperse nanomaterials. This work summarizes the use of deep eutectic solvents in the isolation of cellulosic nanomaterials from different types of biomass. Deep eutectic solvents demonstrate high effectiveness in swelling lignocellulosic biomass and producing cellulose nanomaterials. Overall, deep eutectics solvents represent an innovative and effective pretreatment process for the fractionation of raw cellulose-containing fibres to promote subsequent isolation of nanomaterials made from cellulose.

Parole chiave

  • deep eutectic solvents
  • isolation
  • nanocellulose
  • nanocrystals
  • nanofibers
  • polymers
Accesso libero

DFT studies of camptothecins cytotoxicity III: camptothecin, irinotecan and SN-38

Pubblicato online: 23 Aug 2022
Pagine: 72 - 84

Astratto

Abstract

Geometries of camptothecin, irinotecan, SN-38, and of their hypothetical Cu(II) complexes were optimized at the B3LYP/6-311G* level of theory. Their electron structure, evaluated in terms of Mulliken population analysis and Quantum Theory of Atoms-in-Molecule, was subsequently related to in vitro cytotoxicity. Electron density transfer from the relevant active sites to Cu decreases in the sequence irinotecan > SN-38 > camptothecin. The absolute values of their metal-ligand interaction energies exhibit the same trend. Discrepancy with the least relative in vitro cytotoxicity of irinotecan can be explained by differences in its pharmacokinetics.

Parole chiave

  • Copper(II) probe
  • Cu-ligand interaction energy
  • cytotoxicity estimation
  • electronic structure
Accesso libero

Detoxification and adaptation mechanisms of Trichoderma atroviride to antifungal agents

Pubblicato online: 15 Sep 2022
Pagine: 85 - 96

Astratto

Abstract

Filamentous fungi are crucial for recycling of organic material in nature. In natural habitats, they cope with many stress factors and therefore their adaptation ability to various conditions is very high. Trichoderma sp., fungi used in agriculture as biocontrol agent, are exposed to a variety of toxic molecules including pesticides and fungicides. They have to fight with toxic molecules using stress adaptation mechanisms known as the stress response. Adaptation of fungi to stress, especially to chemical stress, is not well studied in environmental fungal strains. Moreover, the adaptation process presents a risk of resistance mechanism induction to antifungal agents. Such resistant strains could be spread in the environment. This work aims to contribute to the knowledge of the adaptation process spread throughout the fungal kingdom. Transcriptional response of ABC transporters, the main detoxification efflux pumps of subfamily B and G in presence of antifungal agents, is shown. On the other hand, as azoles are the most commonly used antifungal structures in clinical practice and agriculture, changes in important fungal ergosterol biosynthesis genes as a result of their exposure to various azoles structure are highlighted.

Parole chiave

  • adaptation and tolerance mechanisms of filamentous fungi
  • detoxification
  • antifungal agents
Accesso libero

Thermodynamic characterization of acid cryolite systems

Pubblicato online: 15 Sep 2022
Pagine: 97 - 102

Astratto

Abstract

Measuring of the electromotive force in molten system is used to characterize thermodynamic properties of the system at equilibrium. Values of the electromotive force are very important for the determination of activity and standard electrode potential. Investigation of the electromotive force of Al + TiB2 and Al-Al cell was the main aim of this work leading to the characterization of acid cryolite systems. The measurements were realized using a molten aluminum electrode and the electromotive force of an electrochemical cell was investigated in electrolytes at various molar ratios (NaF/AlF3) at equilibrium. Thermodynamic properties were measured in acid cryolite melts at three different temperatures: 800 °C, 900 °C, and 1000 °C, for all experiments.

Parole chiave

  • acid cryolite melts
  • aluminum electrode
  • electromotive force
  • molar ratio
  • standard electrode potential
Accesso libero

Analytical methods for pesticide residues determination in propolis and propolis-based products

Pubblicato online: 11 Oct 2022
Pagine: 103 - 116

Astratto

Abstract

As a result of massive bee deaths in recent years, beekeeping is raising concerns about the presence of pesticides in propolis which is considered as a safe product. The paper is focused on the analysis of bee propolis and propolis-based products using various chromatographic techniques using mass spectrometry detection predominantly. An important part of the work is an overview concerning methods of sample preparation, extraction, and purification of extracts, followed by separation and detection techniques. Positive findings of contaminants and their concentrations in propolis samples and propolis products were evaluated. Sorption based techniques such as matrix solid phase dispersion and solvent-based extraction techniques are frequently applied for propolis analysis in connection with chromatographic techniques. Liquid-based extractions, such as the QuEChERS extraction technique (Quick, Easy, Cheap, Effective, Rugged, Safe), combine extraction by solvent with several ways of extract cleaning using combinations of salts and sorbents, primary secondary amine, MgSO4, NaCl, graphitized carbon, EMR-lipid, florisil, or octadecylsilane-modified silica gel. Other extraction techniques were reviewed. The most significant problem to be considered in pesticides detection is the topic of matrix effects, which have to be solved for each sample analysis with special care.

Parole chiave

  • chromatographic techniques
  • pesticide residues
  • propolis
  • QuEChERS
  • mass spectrometry
Accesso libero

Impact of molecular chain length on polarizabilities of model acenes and oligomers

Pubblicato online: 11 Oct 2022
Pagine: 117 - 122

Astratto

Abstract

A systematic quantum chemical study of model linear oligomers and their ring-fused (condensed) analogues based on six-membered and five-membered aromatic units is presented. Static electric polarizabilities were calculated for optimal geometries. The dependence of electronic and vibrational polarizability contributions on the molecular size was discussed and polymer limits were estimated. The presence of a diradical electronic structure in fused six-membered compounds significantly increases the polarizability values.

Parole chiave

  • Electric properties
  • Organic molecules
  • Diradicals
  • B3LYP
  • Polymer limits
Accesso libero

Modeling of transport properties of binary mixtures including ionic liquids based on their experimental estimation

Pubblicato online: 08 Dec 2022
Pagine: 123 - 130

Astratto

Abstract

Transport properties of selected imidazolium ionic liquids (1-ethyl-3-methylimidazolium acetate, [emim][ac], and 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [bmim][triflate]) as well as of binary mixtures of these ILs with water and ethanol were estimated experimentally. Density data were obtained within the temperature range of 293.15—333.15 K and used for the excess molar volume calculations. For the binary mixtures comprising selected ionic liquids and water/ethanol, partial molar volumes of mixture components were computed and the excess molar volume variation with the mixture composition was correlated using the Redlich-Kister equation. Dependence of viscosity on the binary mixture composition and temperature was described using the Jouyban-Acree model. These data form a base for the assessment of OPEX connected with transportation of mixtures containing these ionic liquids.

Parole chiave

  • imidazolium ionic liquids
  • density
  • dynamic viscosity
  • transportation expenses
14 Articoli
Accesso libero

Ceylon cinnamon and clove essential oils as promising free radical scavengers for skin care products

Pubblicato online: 24 Mar 2022
Pagine: 1 - 11

Astratto

Abstract

Due to adverse effects of free radicals on human skin and increasing consumer demand for natural ingredients, essential oils from basil, Ceylon cinnamon bark, clove, juniper, lavender, oregano, rosemary, tea tree, thyme, and ylang-ylang were assessed for their antiradical activity. The oils were evaluated in the concentration range of 5—0.1 mg·mL−1, in which the three reference synthetic antioxidants are most often added to mass-produced cosmetics. Among all examined samples, C. cinnamon oil at a concentration of 5 mg·mL−1 showed the strongest DPPH radical scavenging activity (0.41 mg·mL−1 IC50), followed by clove oil, BHA, α-tocopherol, and BHT (0.82, 0.84, 0.88 and 0.93 mg·mL−1 IC50), respectively. At the same concentration, the reduction power of C. cinnamon oil was higher (1.64 mg·mL−1 Trolox Eq.) than that of α-tocopherol and BHT (1.42 and 0.80 mmol·L−1 Trolox Eq., respectively) but lower than that of BHA (1.81 mmol·L–1 Trolox Eq.). Antiradical activity of the other eight essential oils was low or negligible. C. cinnamon oil and clove oil are promising antiradical agents for skin care but according to our GC-MS analysis, these oils contain 0.29 % of cinnamaldehyde, 0.03 % of linalool, 0.02 % of D-limonene, and 0.02 % of eugenol or 0.41 % of eugenol and 0.002 % of linalool, respectively, which are monitored contact allergens in cosmetics. Such a product is not be suitable for consumers allergic to these substances but for the vast majority of consumers it does not pose a risk in terms of allergic manifestations.

Parole chiave

  • bark oil
  • oil
  • free radical scavengers
  • skin care products
Accesso libero

On the energetics of radical adduct formation of OH with phenol analogs and aniline

Pubblicato online: 24 Mar 2022
Pagine: 12 - 17

Astratto

Abstract

Theoretical studies on aniline, phenol, benzenethiol, benzeneselenol, and their corresponding adducts with hydroxyl radical in possible positions on a hydrocarbon ring are presented. Bond dissociation enthalpies, related to radical scavenging of primary antioxidants, were calculated using the M06–2X/6–311+G** method. Calculated data were compared with available experimental data. Preferable homolytic bond dissociation of the presented molecules with OH through functional groups X—OH followed by the m–OH ones has been confirmed. The highest antioxidant activity among the investigated positions is predicted for benzeneselenol. Also, the formation of non-covalent van der Waals structures has been shown as important in radical scavenging.

Parole chiave

  • Bond Dissociation Enthalpy
  • DFT
  • hydroxyl radical
  • thermodynamics
Accesso libero

Binary mixtures containing imidazolium ionic liquids: properties measurement

Pubblicato online: 24 Mar 2022
Pagine: 18 - 28

Astratto

Abstract

Densities and transport properties (dynamic viscosity) of pure imidazolium ionic liquids 1-butyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium dicyanamide and their binary mixtures with water and ethanol were measured within the temperature range of 293.15—333.15 K. Obtained experimental data were used to calculate excess molar volume and viscosity deviation. For the chosen binary mixtures, variations of excess molar volume, partial molar volumes of mixture components and of the viscosity deviation with the binary mixture composition were correlated using the Redlich-Kister equation. In addition, variation of viscosity with the binary mixture composition and temperature was fitted using the Jouyban-Acree model.

Parole chiave

  • Imidazolium ionic liquids
  • density
  • dynamic viscosity
  • excess molar volume
  • viscosity deviation
  • Redlich-Kister equation
  • Jouyban-Acree equation
Accesso libero

Thermochemistry of antioxidant action of isoflavones and their deprotonated forms in aqueous solution: hydrogen or electron transfer?

Pubblicato online: 16 May 2022
Pagine: 29 - 35

Astratto

Abstract

Isoflavones possessing several weak acidic hydroxyl groups can undergo successive deprotonations in aqueous solutions. Therefore, their antioxidant properties cannot be ascribed only to the neutral forms but also to corresponding phenoxide anions. It was already confirmed that isoflavones prefer the formation of dianions in aqueous solution. For eight isoflavones and their preferred (poly)deprotonated forms, thermochemistry of hydrogen atom transfer and electron abstraction was studied in terms of corresponding reaction enthalpies, i.e., O—H bond dissociation enthalpies and ionization potentials. Our results clearly indicate that the increase in negative charge causes significant drop in ionization potential and bond dissociation enthalpy. On the other hand, proton affinities show the opposite trend. Thus, it is unfeasible to find a generally valid trend for dianions — corresponding reaction enthalpies strongly depend on the structure of isoflavone, especially on the number/positions of OH groups.

Parole chiave

  • Bond dissociation enthalpy
  • Consecutive deprotonations
  • Electron transfer
  • Phenoxide anion
Accesso libero

Pre-treatment of lignocellulosic materials by enzymatic mixture to enhance biogas production

Pubblicato online: 16 May 2022
Pagine: 36 - 43

Astratto

Abstract

The aim of this study was to evaluate the effect of an enzymatic mixture on the increase of biogas production from lignocellulosic materials as rapeseed straw, maize waste, and wheat straw. For efficient application of the enzymatic mixture, conditions of its use were optimized regarding 50 °C, pH 7 and an enzyme dose of 0.25 % w/v. Biogas potential test confirmed positive effect of the enzymatic mixture on anaerobic digestion of already thermally and alkali pre-treated lignocellulosic materials, as significantly higher biogas production was observed after the enzymatic mixture addition for all monitored substrates. Addition of the enzymatic mixture to the most used substrate at biogas plants — maize silage, had also positive effect on biogas production during the biogas potential test. This fact was not proven during long-term operations of the reactors as the values of total cumulative biogas productions for the whole monitored period from reactors for anaerobic digestion of maize silage with and without addition of enzymatic mixture did not differ significantly.

Parole chiave

  • anaerobic digestion
  • biomass
  • long-term operation
  • maize silage
  • methane
Accesso libero

Nanotextiles — materials suitable for respiratory tract protection but a source of nano- and microplastic particles in the environment

Pubblicato online: 16 May 2022
Pagine: 44 - 53

Astratto

Abstract

The paper deals with the formation of nanomaterials (nanoparticles and nanofibers) in the manufacture and use of respiratory protective equipment. It focuses mainly on processes leading to the release of nanoplastics into the workplace and the environment. Based on selected properties of materials used for the manufacture of protective equipment, their stability in the environment is revealed. The paper demonstrates the impact on the environment considering semichronic phytotoxicity of nanoplastics.

Parole chiave

  • nanofiber
  • electrospinning
  • nonwovens
  • nanoparticles
  • respirator
Accesso libero

Simultaneous detection of purine metabolites by membrane modified electrochemical sensors

Pubblicato online: 23 Aug 2022
Pagine: 54 - 60

Astratto

Abstract

Purine metabolites are important for metabolic and cellular processes. Deregulation of purinergic signaling leads to pathological accumulation of purine degradation products in extracellular fluids and indicates various diseases. In clinical diagnosis at early stages of related diseases, accurate detection of Uric acid and Xanthine is of high importance. Electrochemical methods are fast, simple, sensitive, more convenient, and cost-effective compared to other analytical methods used in purine metabolites signaling. Electrochemical sensors are able to detect more compounds simultaneously. Modification of a glassy carbon electrode sensor with external protective membranes was used in this study to avoid unwanted signal interferences from analyte matrices. Polyvinyl alcohol, Chitosan, and Nafion membranes were selected for sensor modification to compare the electro-neutral, positive and negative charged setting of the Xanthine and Uric acid detection. All three membrane modified sensors showed adequate stability in the phosphate buffer solution after 5 min of incubation and are thus suitable for simultaneous detection of purine metabolites. The best results in anodic peak current response values were observed using the Nafion membrane modified glassy carbon electrode sensor. The approach reported here can be useful for the detection of purine metabolites from various matrices at early stages of clinical diagnosis.

Parole chiave

  • electrochemistry
  • GCE
  • Chitosan
  • Nafion
  • purine metabolites
  • PVA
Accesso libero

The role of deep eutectic solvents in the production of cellulose nanomaterials from biomass

Pubblicato online: 23 Aug 2022
Pagine: 61 - 71

Astratto

Abstract

In recent years, the demand for environment-friendly products has been on an increasing trend among researchers and industry for sustainable development. Deep eutectic solvents are green solvents which, due to their properties (biodegradability, recyclability, low cost, availability, easy preparation, low toxicity, chemical and thermal stability), can be used in various fields such as polymer chemistry, which includes nanocellulose isolation and polysaccharides processing. Several studies have illustrated the effectiveness of using deep eutectic solvents instead of the conventional reaction system to produce and disperse nanomaterials. This work summarizes the use of deep eutectic solvents in the isolation of cellulosic nanomaterials from different types of biomass. Deep eutectic solvents demonstrate high effectiveness in swelling lignocellulosic biomass and producing cellulose nanomaterials. Overall, deep eutectics solvents represent an innovative and effective pretreatment process for the fractionation of raw cellulose-containing fibres to promote subsequent isolation of nanomaterials made from cellulose.

Parole chiave

  • deep eutectic solvents
  • isolation
  • nanocellulose
  • nanocrystals
  • nanofibers
  • polymers
Accesso libero

DFT studies of camptothecins cytotoxicity III: camptothecin, irinotecan and SN-38

Pubblicato online: 23 Aug 2022
Pagine: 72 - 84

Astratto

Abstract

Geometries of camptothecin, irinotecan, SN-38, and of their hypothetical Cu(II) complexes were optimized at the B3LYP/6-311G* level of theory. Their electron structure, evaluated in terms of Mulliken population analysis and Quantum Theory of Atoms-in-Molecule, was subsequently related to in vitro cytotoxicity. Electron density transfer from the relevant active sites to Cu decreases in the sequence irinotecan > SN-38 > camptothecin. The absolute values of their metal-ligand interaction energies exhibit the same trend. Discrepancy with the least relative in vitro cytotoxicity of irinotecan can be explained by differences in its pharmacokinetics.

Parole chiave

  • Copper(II) probe
  • Cu-ligand interaction energy
  • cytotoxicity estimation
  • electronic structure
Accesso libero

Detoxification and adaptation mechanisms of Trichoderma atroviride to antifungal agents

Pubblicato online: 15 Sep 2022
Pagine: 85 - 96

Astratto

Abstract

Filamentous fungi are crucial for recycling of organic material in nature. In natural habitats, they cope with many stress factors and therefore their adaptation ability to various conditions is very high. Trichoderma sp., fungi used in agriculture as biocontrol agent, are exposed to a variety of toxic molecules including pesticides and fungicides. They have to fight with toxic molecules using stress adaptation mechanisms known as the stress response. Adaptation of fungi to stress, especially to chemical stress, is not well studied in environmental fungal strains. Moreover, the adaptation process presents a risk of resistance mechanism induction to antifungal agents. Such resistant strains could be spread in the environment. This work aims to contribute to the knowledge of the adaptation process spread throughout the fungal kingdom. Transcriptional response of ABC transporters, the main detoxification efflux pumps of subfamily B and G in presence of antifungal agents, is shown. On the other hand, as azoles are the most commonly used antifungal structures in clinical practice and agriculture, changes in important fungal ergosterol biosynthesis genes as a result of their exposure to various azoles structure are highlighted.

Parole chiave

  • adaptation and tolerance mechanisms of filamentous fungi
  • detoxification
  • antifungal agents
Accesso libero

Thermodynamic characterization of acid cryolite systems

Pubblicato online: 15 Sep 2022
Pagine: 97 - 102

Astratto

Abstract

Measuring of the electromotive force in molten system is used to characterize thermodynamic properties of the system at equilibrium. Values of the electromotive force are very important for the determination of activity and standard electrode potential. Investigation of the electromotive force of Al + TiB2 and Al-Al cell was the main aim of this work leading to the characterization of acid cryolite systems. The measurements were realized using a molten aluminum electrode and the electromotive force of an electrochemical cell was investigated in electrolytes at various molar ratios (NaF/AlF3) at equilibrium. Thermodynamic properties were measured in acid cryolite melts at three different temperatures: 800 °C, 900 °C, and 1000 °C, for all experiments.

Parole chiave

  • acid cryolite melts
  • aluminum electrode
  • electromotive force
  • molar ratio
  • standard electrode potential
Accesso libero

Analytical methods for pesticide residues determination in propolis and propolis-based products

Pubblicato online: 11 Oct 2022
Pagine: 103 - 116

Astratto

Abstract

As a result of massive bee deaths in recent years, beekeeping is raising concerns about the presence of pesticides in propolis which is considered as a safe product. The paper is focused on the analysis of bee propolis and propolis-based products using various chromatographic techniques using mass spectrometry detection predominantly. An important part of the work is an overview concerning methods of sample preparation, extraction, and purification of extracts, followed by separation and detection techniques. Positive findings of contaminants and their concentrations in propolis samples and propolis products were evaluated. Sorption based techniques such as matrix solid phase dispersion and solvent-based extraction techniques are frequently applied for propolis analysis in connection with chromatographic techniques. Liquid-based extractions, such as the QuEChERS extraction technique (Quick, Easy, Cheap, Effective, Rugged, Safe), combine extraction by solvent with several ways of extract cleaning using combinations of salts and sorbents, primary secondary amine, MgSO4, NaCl, graphitized carbon, EMR-lipid, florisil, or octadecylsilane-modified silica gel. Other extraction techniques were reviewed. The most significant problem to be considered in pesticides detection is the topic of matrix effects, which have to be solved for each sample analysis with special care.

Parole chiave

  • chromatographic techniques
  • pesticide residues
  • propolis
  • QuEChERS
  • mass spectrometry
Accesso libero

Impact of molecular chain length on polarizabilities of model acenes and oligomers

Pubblicato online: 11 Oct 2022
Pagine: 117 - 122

Astratto

Abstract

A systematic quantum chemical study of model linear oligomers and their ring-fused (condensed) analogues based on six-membered and five-membered aromatic units is presented. Static electric polarizabilities were calculated for optimal geometries. The dependence of electronic and vibrational polarizability contributions on the molecular size was discussed and polymer limits were estimated. The presence of a diradical electronic structure in fused six-membered compounds significantly increases the polarizability values.

Parole chiave

  • Electric properties
  • Organic molecules
  • Diradicals
  • B3LYP
  • Polymer limits
Accesso libero

Modeling of transport properties of binary mixtures including ionic liquids based on their experimental estimation

Pubblicato online: 08 Dec 2022
Pagine: 123 - 130

Astratto

Abstract

Transport properties of selected imidazolium ionic liquids (1-ethyl-3-methylimidazolium acetate, [emim][ac], and 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [bmim][triflate]) as well as of binary mixtures of these ILs with water and ethanol were estimated experimentally. Density data were obtained within the temperature range of 293.15—333.15 K and used for the excess molar volume calculations. For the binary mixtures comprising selected ionic liquids and water/ethanol, partial molar volumes of mixture components were computed and the excess molar volume variation with the mixture composition was correlated using the Redlich-Kister equation. Dependence of viscosity on the binary mixture composition and temperature was described using the Jouyban-Acree model. These data form a base for the assessment of OPEX connected with transportation of mixtures containing these ionic liquids.

Parole chiave

  • imidazolium ionic liquids
  • density
  • dynamic viscosity
  • transportation expenses