Abstract Four ionic Ni(II) complexes containing the [Ni(H im ) 6 ] 2+ (H im = imidazole) complex cation were prepared: [Ni(H im ) 6 ](CO 3 )·5H 2 O ( 1 ), [Ni(H im ) 6 ]( ac ) 2 ·H 2 O ( 2 , ac = acetate), [Ni(H im ) 6 ](NO 3 ) 2 ( 3 ), and [Ni(H im ) 6 ]SiF 6 ( 4 ); complexes 2 and 4 are new. The prepared complexes were characterized chemically and spectroscopically. Results of X-ray single crystal studies have shown that all four complexes exhibit ionic crystal structures comprising [Ni(H im ) 6 ] 2+ complex cations, the respective anion(s), and in case of 1 and 2 , additional solvate water molecules. Ni(II) central atoms in all complexes 1 — 4 are hexa-coordinated by six N-atoms originating from monodentate H im ligands. While in 1 and 4 the NiN 6 chromophore is quite a regular octahedron with only one independent Ni—N bond, as imposed by local symmetry, in 2 and 3 the octahedra are slightly deformed. On the other hand, significant differences were observed in the orientation of H im rings within the respective coordination polyhedra.
Two novel potent perfluorophenylhydrazone derivatives, 1-((5-nitrothiophen-2-yl)methylene)-2-(per- fluorophenyl)hydrazine, (I), and 1-((5-nitrofuran-2-yl)methylene)-2-(perfluorophenyl) hydrazine, (II), are introduced, with suggested improvement by further design. Their multitarget structures and features have been combined to create potential AD therapeutics. Crystals (I) and (II) are molecules with two rings and a hydrazone part at the centre of the molecule. They were synthesised and characterised using elemental and spectroscopic (1H-NMR) analyses and their crystal structures were determined using the single-crystal X-ray diffraction method. The structures crystallise in the monoclinic space group with Z = 2 and Z = 4 molecules per unit cell. Compound (I) crystallises as a dimer in the non-centrosymmetric space group, while compound (II) crystallises as a racemate in the centrosymmetric space group. The "absolute configuration and conformation for bond values" were not derived from anomalous dispersion (rmad). The crystal structures reveal diverse non-covalent interactions such as intra- and inter-hydrogen bonding, pi-ring - pi-ring, C-H - pi-ring interactions. The expected stereochemistry of hydrazone atoms C7, N2, and N1 was confirmed for compounds (I) and (II). Both molecules possess a "boat conformation" resembling a 6-membered ring. Results of the single crystal studies were reproduced using the Hirshfeld surface analysis, Gaussian software, and QTAIM contour mapping.
Four ionic Ni(II) complexes containing the [Ni(Him)6]2+ (Him = imidazole) complex cation were prepared: [Ni(Him)6](CO3)& centerdot;5H2O (1), [Ni(Him)6](ac)2 & centerdot;H2O (2, ac = acetate), [Ni(Him)6](NO3)2 (3), and [Ni(Him)6]SiF6 (4); complexes 2 and 4 are new. The prepared complexes were characterized chemically and spectroscopically. Results of X-ray single crystal studies have shown that all four complexes exhibit ionic crystal structures comprising [Ni(Him)6]2+ complex cations, the respective anion(s), and in case of 1 and 2, additional solvate water molecules. Ni(II) central atoms in all complexes 1-4 are hexa-coordinated by six N-atoms originating from monodentate Him ligands. While in 1 and 4 the NiN6 chromophore is quite a regular octahedron with only one independent Ni-N bond, as imposed by local symmetry, in 2 and 3 the octahedra are slightly deformed. On the other hand, significant differences were observed in the orientation of Him rings within the respective coordination polyhedra.
Aflatoxin M 1 (AFM 1 ), which is a hydroxylated metabolite of aflatoxin B 1 , can be irreversibly bound to casein micelles and thus, its higher content is measured in cheese than in the original milk. The present study describes validation of a reliable and rapid method for AFM 1 content determination in cheese applied to 36 kinds of cheese sold in Slovakia during the spring of 2024. The method consisted of three basic steps: extraction of AFM 1 from cheese, purification of extracts using immunoaffinity columns, and determination of AFM 1 content by high performance liquid chromatography with fluorescence detection. Suitability of the method was proved by the limits of detection and quantification equal to 2.0 and 6.0 ng/kg, respectively, which is in accordance with the limits set by European legislation for analytical procedures for AFM 1 determination in milk. Accuracy of the method was determined using a recovery test, spiking cheese with AFM 1 , and varied between 87.8 and 100.5 %. Precision was confirmed by low relative standard deviations, 0.3—7.9 %, and Hor- Rat values (0.01—0.32) of the results obtained on different days. Experiments showed the AFM 1 content in all cheese to be below the limit of quantification, which indirectly confirmed the absence of AFM 1 in milk as raw material. However, AFM 1 contamination of milk is expected to increase due to global warming in future; therefore, AFM 1 contamination should be an essential part of current food safety issues.
Catalytic styrene Ph-CH=CH2 oxidation is assumed to be a simple reaction procedure; however, its details require further systematic research. Using quantum-chemical treatment, relevant intermediates have been investigated in various charge and spin states of alternative reaction pathways of styrene oxidation by hydroperoxyl using the [CuL]- catalyst, where H2L = trans-2,9-dibutyl-7,14-dimethyl-5,12-di(4-methoxyphenyl)-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione. Within reaction pathway A, the neutral hydroperoxyl radical is bonded to Cu to form 2[CuL(OOH)]-. Subsequent addition of neutral styrene results in the formation of 2{[CuL(OH)](Ph-CH2-CHO)}-. Reaction pathway B starts with the initial non-radical formation of the pi-complex 1[CuL(Ph-CH=CH2)]- which is problematic due to its endothermic character. Subsequent addition of a hydroperoxyl radical leads to 2{CuL[Ph-CH(OOH)-CH2]}- and its oxidation leads to the separation of Ph-CH(OOH)-CH2. The exothermic reaction path A is preferred over the endothermic reaction path B.
From the system [Ni(o-van-en) ] - DyBr3, a novel tetranuclear complex [Ni(o-van-en) Dy(H2O)2(OH)]2Br46H2O (1) was isolated; H2(o-van-en) was synthesized by 2/1 condensation of o-vanillin and ethylenediamine. Single crystals (SC) of 1, upon standing in methanol/isopropanol mother liquor, underwent a SC-SC transformation and yielded a new solvatomorph [Ni(o-van-en)Dy(H2O)2(OH)]2Br4MeOH iPrOHH2O (2). Both complexes, 1 and 2, were characterized by elemental analysis, infrared spectroscopy, and single crystal X-ray analysis. Crystal structures of both 1 and 2 are ionic. Within the bicompartmental unit {Ni(o-van-en)Dy(H2O)2(m-OH)}, the square coordinated Ni(II) atom occupies the smaller cavity (donor set is cis-N2O2) while the octacoordinated Dy(III) atom (donor set is O8) is placed in the larger cavity. The two [Ni(o-van-en)Dy(H2O)2(m-OH)] units are linked by a pair of m-OH bridging ligands. The unit cell content is completed by bromide anions and water (1) or methanol, isopropanol, and water solvate molecules (2).
This study aimed to quantify the weight loss of coffee cream (10 % fat) packaged in 10 g and 5 g polystyrene (PS) tubes over 316 days. A total of 13,760 weight measurements were performed across four production batches. Significant linear dependence between the absolute weight of coffee cream and time was observed, with negative slopes of -0.009 g/d and -0.007 g/d, and R-2 values of 0.990 and 0.996 for 10 g and 5 g tubes, respectively. Considering the surface area of the PS tube without its aluminium lid, water vapour transmission rates were calculated as 3.34 +/- 0.08 g/m(2)d for 10 g tubes and 2.56 +/- 0.07 g/m(2)d for 5 g tubes. Time required to decrease the weight of the cream by 10 % was 137.0 +/- 3.0 days for 10 g fillings and 84.0 +/- 1.9 days for 5 g fillings. Conversely, a loss of 1 g occurred over 110.7 +/- 2.4 days and 144 +/- 3.3 days in 10 g and 5 g tubes, respectively. These findings provide producers with an estimate of the excess amount of coffee cream needed to maintain the declared value in PS packaging material, depending on the intended shelf life.
Geometry of neutral [Hn{Co(mu 2-CO)(PMe3)2}3] complexes, n = 0 -> 4, in three lowest spin states was optimized at the B3LYP/6-311G* level of theory with GD3 dispersion correction. The most stable quartet spin state was found for [{Co(mu 2-CO)(PMe3)2}3] whereas the doublet or triplet spin states are the most stable in the remaining complexes. Hydrogenation of [{Co(mu 2-CO)(PMe3)2}3] to the complexes with mu 3-H bridges is more advantageous at lower temperatures. Trigonal symmetry is preserved only in [(mu 3-H){Co(mu 2-CO)(PMe3)2}3]. Neutral H2 units in [(H2){Co(mu 2-CO)(PMe3)2}3], [(H2)(mu 3-H){Co(mu 2-CO)(PMe3)2}3], and [(H2)2{Co(mu 2-CO)(PMe3)2}3] are only physisorbed and show vanishing spin density. Spin density is concentrated dominantly at positively charged Co atoms and only the vanishing spin density is located at the negatively charged mu 3-H atoms. There are no Co-Co bonds and the Co3 triangles are held together only by mu 2-CO and mu 3-H bridges.
This work focuses on the influence of solid-state fermentation on the polyphenols and flavonoids conent in fruit pomace of apple, aronia, and sea buckthorn. A comparison was made during a seven-day fermentation of pomace with A. niger and with autochthonous microflora, showing that this method has no significance for aronia and sea buckthorn pomace. Autochthonous microflora had a more favorable effect on the content of polyphenols and flavonoids than A. niger. However, in the case of apple pomace, the content of total polyphenols increased up to 1425 mg GAE/100 g DW on the seventh day of fermentation with A. niger , representing a 7.3-fold increase compared to the initial value of 195 mg GAE/100 g DW. Our results therefore present an attractive way of agro-waste utilization and the subsequent implementation of these isolates in other types of industry.
Aggregation of proteins naturally occurs during different stages of cultivation and downstream processes and is often associated with quality reduction in the final product. Therefore, determining the presence of aggregates is important. In this study, a fluorescence-based analytical method using the dye Nile red was developed for antibody aggregates quantification. The fluorescence assay demonstrated selectivity and sensitivity towards hydrophobic surfaces of aggregates within reliable quantification range of 0.0165—1.65 g/L. Validation confirmed high reproducibility, with intra-assay and inter-assay coefficients of variation within acceptable limits. The dye was stable in commonly used buffer systems and in the presence of salts. Comparative analysis of SEC and fluorescence methods indicated that fluorescence detection remains sensitive to aggregation beyond SEC’s detection threshold. Thermal stability studies revealed that polyclonal antibodies have higher resistance to thermal stress than monoclonal antibodies, which suggests that structural variability plays an important role in thermal stability. Additionally, antibody aggregation was shown to be pH-dependent, with increased aggregation at both low and high pH levels. Polyclonal antibodies were stable at pH 5—6. In more acidic conditions, soluble aggregates were formed, while at neutral and basic pH, aggregation was accompanied by the formation of insoluble particles. The effect of salts on aggregation was variable, with NaCl promoting aggregation at high concentrations, NaSCN facilitating dissociation of aggregates, and Na 2 SO 4 inducing precipitation. Guanidine HCl exhibited a stabilizing effect, preventing aggregation over time.
Microbial growth responses of probiotic Lacticaseibacillus rhamnosus GG with well-documented health effects were studied in an oat-based milk alternative in the biokinetic temperature range of 8 to 44 °C. The applied Baranyi model (with a fixed parameter value h 0 = 0.407) fitted the growth data well, as shown by the goodness of fit measures ( R 2 = 0.995; RMSE = 0.153) for the total experimental data set (n = 245). Using the initial inoculations of 2.7 ±0.1 log CFU.ml −1 , the maximal population density (MPD) of 8.3 ±0.4 log CFU. ml −1 was reached in stationary phase in the temperature range from 12 to 37 °C. Slightly lower MPDs were recorded at higher temperatures, 40 and 44 °C, while an increase in only 1 log was reached at 8 °C. Thus, the MPD 3.7 log CFU.ml −1 was only estimated. Based on the experiments, the highest specific growth rate ( μ max ) of 0.800 −1 and the shortest lag phase ( λ ) of 0.51 h were observed at 40 °C. The Ratkowsky modified square root model (mSQRT) was used in the secondary modelling for μ max values and the cardinal parameters minimum and maximum temperature were determined: T min = 4.2 °C; T max = 47.8 °C. As drinks of plant origin are produced in large volumes, the production of their fermented varieties is expected to appear in a short time. This is why providing parameters on kinetic behaviour of L. rhamnosus GG is essential for industrial process design and further scale up of fermented dairy-free matrice with probiotic potential.
Aflatoxin M 1 (AFM 1 ), which is a hydroxylated metabolite of aflatoxin B 1 , can be irreversibly bound to casein micelles and thus, its higher content is measured in cheese than in the original milk. The present study describes validation of a reliable and rapid method for AFM 1 content determination in cheese applied to 36 kinds of cheese sold in Slovakia during the spring of 2024. The method consisted of three basic steps: extraction of AFM 1 from cheese, purification of extracts using immunoaffinity columns, and determination of AFM 1 content by high performance liquid chromatography with fluorescence detection. Suitability of the method was proved by the limits of detection and quantification equal to 2.0 and 6.0 ng/kg, respectively, which is in accordance with the limits set by European legislation for analytical procedures for AFM 1 determination in milk. Accuracy of the method was determined using a recovery test, spiking cheese with AFM 1 , and varied between 87.8 and 100.5 %. Precision was confirmed by low relative standard deviations, 0.3—7.9 %, and Hor- Rat values (0.01—0.32) of the results obtained on different days. Experiments showed the AFM 1 content in all cheese to be below the limit of quantification, which indirectly confirmed the absence of AFM 1 in milk as raw material. However, AFM 1 contamination of milk is expected to increase due to global warming in future; therefore, AFM 1 contamination should be an essential part of current food safety issues.
The logarithm of octanol-water partition coefficient (log P ) is estimated by means of six parametric methods (iLOGP, XLOGP3, WLOGP, MLOGP, SILICOS-IT, OBLogP) and six quantum mechanics (QM) based models. QM models comprise DFT functional choice (B3LYP, M06-X, PBE0, including the xTB parametrization variant), implicit solvent model choice (IEFPCM, SMD, or ALPB), and basis set quality in DFT calculations (6-31G* and 6-311++G**). Several statistics are evaluated to compare Clog P estimates to experimentally measured dataset of 36 molecules picked from Meylan and Howard J. Pharm. Sci. 84 (1995) 83—92. ChemmineR cluster analysis has been performed to confirm structural diversity of molecules in the employed molecular dataset. XLOGP3 performance is the best among all the methods used, while SMD based DFT models showed a clearly competitive results with the remaining parametric methods irrespective of DFT functional or basis set quality.
This work provides a systematic theoretical study on gas-phase bond dissociation enthalpies for homolytic C-H bond cleavage in linear and branched alkanes. Quantum chemical calculations were performed using the density functional theory (DFT) and ab initio composite (G4(MP2), G4) methods. In case of DFT calculations, the M06-2X and B3LYP functionals combined with 6-311++G**, aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ basis sets were covered. In linear molecules, the best agreement with experiment was observed for B3LYP/aug-cc-pVQZ. In both composite approaches, as the number of C atoms increases, the BDE values are affected by the systematic error of the method. For example, G4 BDE of terminal -CH3 group of hexane is 422.6 kJmol-1 while for undecane it is 415.5 kJmol-1. On the contrary, the composite methods are in better agreement with experiments compared to the DFT approaches for simple branched hydrocarbons.
In this work, theoretical and experimental study of monoethanolamides (MEAD) and diethanolamides (DEAD) is presented. The aim was to investigate the thermodynamics of addition reactions used in the synthesis of MEAD and DEAD. The reactions have exothermic character and alkyl elongation affects the reaction enthalpy of DEAD production reactions. In the experimental part, the prepared MEAD and DEAD samples were preliminary tested as a potential additive in diesel fuel. The research focused on measuring three key properties: i.e., foaming, lubricity, and cetane number. The results suggest that MEAD is a suitable additive for diesel fuel.
Adsorption of copper atom on benzene surface has been studied at the ab initio MP2 and CCSD(T) theory levels. CCSD(T)/CBS binding energies of the copper atom adsorbed on hollow, top, and bridge positions are 16.77, 19.27 and 21.08 kJ/mol, respectively. Adsorption at the bridge position represents the most stable structure of the Cu-benzene complex with charge transfer from benzene to the copper atom playing a key role.
Anilines and their derivatives are used in industrial production of dyes, pharmaceuticals, plastics, and synthetic antioxidants. Abstraction of electron and formation of a cation radical represent a significant step in the reactivity of this group of substances. The aim of this study was to theoretically investigate the effect of a substituent on the oxidative electrochemical potential of 64 species of aniline derivatives. Quantum-chemical calculations were performed using the composite G4 method. The obtained linear dependences for reaction Gibbs free energies were correlated with the Hammett constants and available experimental values.
Soya beans, a vital source of protein, oil, and dietary fibre, are cultivated extensively, with a growing demand since 1950. However, the extensive use of pesticides in soya bean cultivation poses potential risks to human health and the environment, especially given the lack of strict regulations for maximum residue levels in soya-based products within the European Union. This study provides a comprehensive overview of isolation and determination methods of pesticide residues from soya products, emphasising the challenges posed by the high-fat content of soya beans. Various chromatographic techniques coupled with mass spectrometry are discussed for their efficacy in pesticide residues analysis. The manuscript also reviews sample preparation techniques, with a focus on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method, and its modifications to enhance extraction and purification efficiency. Additionally, the study explores the application of liquid-liquid extraction and solid-phase extraction in the analysis of soya oil and beverages and innovative methods, such as dispersive liquid-liquid microextraction and matrix solid-phase dispersion, for comprehensive pesticide residue analysis. This review highlights the importance of multiresidue analytical methods in ensuring the safety of soya products thereby supporting regulatory compliance and public health protection.
As people spend many hours looking at digital screens, the negative effects of artificial blue light are becoming more apparent. While most research has focused on its effects on eyes, less is known about the effects of blue light on the skin, where similar photoreceptors are located. Unlike the sunscreens against UVB and UVA radiation, there is no standard method for determining skin protection against blue light. The lipophilic complex Carotolino, a system combining carrot root extract, carrot seed oil, and beta-carotene, was chosen as a model substance for this research. Spectrophotometric investigation demonstrated the ability of Carotolino to absorb radiation in the blue light region (400-500 nm). After a 60-minute LED@450 nm exposure, corresponding to the maximum wavelength of radiation from the displays of common smartphones, only small changes (1.4 %) in the optical spectra were observed. The spectra showed sufficient photostability of Carotolino and its stabilizing effect on the photolabile Ubiquinone. In the 415-455 nm wavelength range associated with oxidative stress, Carotolino (0.4 % wt.) reduced blue light by similar to 97.0 %. EPR spin trapping showed that blue light with a maximum wavelength of 450 nm causes significant formation of reactive free radicals, which can be partially eliminated by the application of Carotolino. The results confirmed the suitability of both methods to evaluate the effectiveness of substances to reduce physical impact of incident light on the skin. Further methods are needed to investigate biological protection of skin against blue light by promising substances.
The geometry of trans-HN=NH, cis-HN=NH and N=NH2 containing no, one or two 15N labeled atoms was optimized. The corresponding infrared vibrations were evaluated using a linear scaling factor. For each of these compounds at least one vibration can be found, which enables to distinguish between heteroisotopic 14N=15N and homoisotopic 14N=14N or 15N=15N species. Independent of the 15N labeling, only trans-conformation should be found in the reaction mixture under equilibrium conditions.
