Search Results (57)

The aim of this paper was to evaluate the effect of two different matrices (e.g., starch base flour vs. protein base flour) on the ability of near-infrared (NIR) spectroscopy to classify binary mixtures of chickpea (protein), corn and tapioca (starch) flours. Binary mixtures were made by mixing different proportions of chickpea plus corn, chickpea plus tapioca, and corn plus tapioca flour. Spectra were collected using NIR spectroscopy and the data analyzed using techniques such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed an effect of the matrix on the PLS-DA classification results, in both classification rates and PLS loadings. The different combinations of flours/mixtures showed changes in absorbance values around 4752 cm⁻¹ that are associated with starch and protein. Nevertheless, the use of NIR spectroscopic might provide a valuable initial screening and identification of the potential contamination of flours along the supply and value chains, enabling more costly methods to be used more productively on suspect samples. Full article

Cuticular hydrocarbon (CHC) profiling shows promise as a chemotaxonomic tool for identifying and discriminating between closely related insect species. However, there have been limited studies using CHC profiling to differentiate between weevil species (Coleoptera: Curculionidae). This proof-of-concept study investigated the use of CHC and volatile profiling to discriminate between five weevil species from three genera in the Gonipterini tribe. A total of 56 CHCs and 41 other volatile compounds were found across the five species, with 83 of the compounds being identified through their mass fragmentation patterns. The number of CHCs from each species ranged from 20 to 43, while the proportion of CHCs unique to each species varied between 0% and 19%. The most abundant CHCs were nonacosane, 7-methylheptacosane, heptacosane, and hexacosane. Principal component analysis of the centred log-ratio transformed data revealed broad differences in CHC profiles between the two Oxyops species, with Bryachus squamicollis demonstrating the greatest divergence from the other Gonipterini species. The results suggest that CHC analysis could be used to support established taxonomic methods, including morphological features and genetic sequencing results. Full article

In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe₃O₄@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe₃O₄@G-F was successfully prepared by grafting fluorinated polyether onto Fe₃O₄ and graphene-oxide composites. Fe₃O₄@G-F was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Taking the self-made crude-oil emulsion as the experimental object, the demulsification mechanism of the demulsifier and the influence of external factors, such as the temperature and pH value, on the demulsification performance of the demulsifier are discussed. The results show that the demulsification efficiency of the Fe₃O₄@G-F emulsion can reach 91.38% within 30 min at a demulsifier dosage of 750 mg/L, pH of 6, and a demulsification temperature of 60 °C. In neutral and acidic environments, the demulsification rate of the demulsifier is more than 90%. In addition, Fe₃O₄@G-F has been proven to have good magnetic effects. Under the action of an external magnetic field, Fe₃O₄@G-F can be recycled and reused in a two-phase system four times, and the demulsification efficiency is higher than 70%. This magnetic nanoparticle demulsifier has broad application prospects for various industrial and environmental processes in an energy-saving manner. Full article

Living systems, whether healthy or diseased, must obey the laws of chemistry. The purpose of this review is to identify the interpretive limits of cellular biochemistry using, largely, the tools of physical chemistry. We illustrate this approach using two major concepts in cancer: carcinogenicity and cancer recurrences. Cells optimize the chemical performance of enzymes and pathways during cancer recurrences. Biology has been primarily concerned with the analysis of high affinity interactions, such as ligand–receptor interactions. Collective weak interactions (such as van der Waals forces) are also important in determining biosystem behaviors, although they are infrequently considered in biology. For example, activity coefficients determine the effective concentrations of biomolecules. The in vivo performance of enzymes also depends upon intracellular conditions such as high protein concentrations and multiple regulatory factors. Phase separations within membranes (two dimensions) and nucleoli (three dimensions) are a fundamental regulatory factor within cells, as phase separations can alter reactant concentrations, local dielectric constants, and other factors. Enzyme agglomeration also affects the performance of biochemical pathways. Although there are many examples of these phenomena, we focus on the key steps of cancer: carcinogenicity and the biochemical mechanism of cancer recurrences. We conjecture that oxidative damage to histones contributes to carcinogenicity, which is followed by nucleolar phase separations and subsequent DNA damage that, in turn, contributes to the redistribution of enzymes mediating metabolic changes in recurrent breast cancer. Full article

By investigating the hydrophobic properties and functional components including ethyl caproate (EC), caproic acid (CA), isoamyl acetate (IA), isoamyl alcohol (IAA), isovaleraldehyde (IVA), and procyanidin B2 (PB2) in beverages, one can incorporate them with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipids to create cell-sized lipid vesicles. The aim of this study was to explore the correlation between the concentration of flavors or functional compounds and the size of the lipid vesicles. It was observed that EC, CA, IA, and IAA decreased the size of lipid vesicles. In contrast, IVA and PB2 increased their size. To comprehend this correlation, both the chemical structure of these compounds in relation to DOPC membranes and the fluidity of the membranes were considered. The size of the lipid vesicles was influenced by the molecular interactions between the compounds and DOPC. Those were caused by, in particular, the balance between hydrophobicity and hydrophilicity. Compounds with higher hydrophobicity tended to decrease the size of the lipid vesicles, whereas compounds with greater hydrophilicity had the opposite effect, leading to an increase in size. These findings suggest that the size of lipid vesicles can serve as a potential indicator for rapidly evaluating the concentration of these components in beverages. Full article

A promising carrier for the development of polymer systems with controlled release of biologically active compounds is the aminopolysaccharide chitosan. In the present work, we studied the possibility of using chitosan films as a matrix for the N⁶-benzyladenine (BA), which is the natural cytokinin widely used in tissue culture. The aim of this work was to develop biopolymer carriers containing phytohormones cytokinins that provide its controlled release. As a result of the work, a number of biopolymer carriers containing BA were obtained, and the kinetics of moisture absorption of the resulting complexes and the kinetics of their release of cytokinins were studied. It has been shown that the use of a polymer carrier based on chitosan is a convenient matrix for achieving a prolonged biological effect from cytokinins. The obtained results will make it possible to purposefully design materials with an optimal delivery rate of cytokinins for a biological object. Full article

Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP-bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 °C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products. Full article

The CO₂ reduction by solar means has been discussed as an alternative to emission abatement, a fundamental topic for sustainable, carbon-free production in the future. However, the choice of efficient systems, starting with the catalysts, is still a critical issue, especially due to the poor activity of available options. Polyoxometalates have been extensively studied as promising photocatalysts due to their semiconducting properties. Nevertheless, the synthetic conditions of polyoxoniobate are stringent due to the low reaction activity of Nb species, the lack of soluble precursors, and the narrow pH range. Unlike the literature, in the present study, we report a simple polyoxoniobate synthesis method. This synthesis method has some remarkable features, such as low processing time and temperature and good activity and selectivity in the CO₂ photoreduction process. The results revealed an outstanding efficiency for the CO₂ reduction reaction with a high selectivity of CO₂ to CO conversion (92.5%). Furthermore, C2 compounds (e.g., acetate) were produced in the liquid phase of the reaction system. Our findings are significant for indicating the potential of polyoxoniobate for CO₂ photoreduction, which opens a way to control competitive reactions with synthesis, leading to higher selectivity. Full article

The processes of the sublimation and thermal decomposition of the 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (EMImPF₆) were studied by a complex approach including Knudsen effusion mass spectrometry, IR and NMR spectroscopy, and quantum chemical calculations. It was established that the vapor over the liquid phase primarily consists of decomposition products under equilibrium conditions. Otherwise, the neutral ion pairs are the only vapor components under Langmuir conditions. To identify the nature of the decomposition products, an experiment on the distillation of the ionic liquid was performed and the collected distillate was analyzed. It was revealed by the IR and NMR spectroscopy that EMImPF₆ decomposes to substituted imidazole-2-ylidene (C₆N₂H₁₀PF₅) and HF. The measured vapor pressure of C₆N₂H₁₀PF₅ reveals a very low activity of the decomposition products (<10⁻⁴) in the liquid phase. The absence of a significant accumulation of decomposition products in the condensed phase makes it possible to determine the enthalpy of sublimation of the ionic liquid assuming its unchanged activity. The thermodynamics of the EMImPF₆ sublimation was studied by Knudsen effusion mass spectrometry. The formation enthalpy of EMImPF₆ in the ideal gas state was found from a combination of the sublimation enthalpy and formation enthalpy of the ionic liquid in the condensed state. The obtained value is in good agreement with those calculated by quantum chemical methods. Full article

Residual solvents in pharmaceutical excipients, active pharmaceutical ingredients (APIs), and finished products are usually analyzed using gas chromatography (GC)-based techniques according to a pharmacopeial monograph, such as the United States Pharmacopeia’s (USP) chapter <467>. GC analyses are often slow, which limits sample throughput. Selected ion flow tube mass spectrometry (SIFT-MS) removes the rate-limiting chromatographic separation step, potentially offering faster sample analyses. This approach was demonstrated recently with the publication of an alternative SIFT-MS procedure which was successfully validated against the performance criteria in USP chapter <1467>. The present study expands upon the previous work by conducting a head-to-head comparison of GC-flame ionization detection (GC-FID) and SIFT-MS procedures. The results obtained in this cross-platform study demonstrated similar performance for the GC-FID and SIFT-MS procedures for linearity (R² > 0.94 and 0.97, respectively) and repeatability (<17%RSD and <10%RSD). For accuracy and recovery, acceptance criteria (within 20%) were achieved for most compounds across the two drug products (SIFT-MS suffered fewer failures, possibly due to shorter wait times prior to analysis). Additionally, SIFT-MS analyzed samples over 11-fold faster than GC-FID, increasing daily sample throughput and reducing the time taken to determine the result. This study therefore suggests that residual solvent analysis using SIFT-MS may support workflow improvements for pharmaceutical manufacturers. Full article

The awareness of the origin of meat that people consume is rapidly increasing today and with that increases the demand for fast and accurate methods for its distinction. In this work, we present for the first time the application of Raman spectroscopy using a portable spectrometer for the classification of pork. Breeding conditions were distinguished from spectral differences of adipose tissues. The pork samples were obtained from Dutch vendors, from supermarkets with quality marks of 1 and 3 stars, and from a local butcher shop. In total, 60 fat samples were examined using a fiber-optic-coupled Raman spectrometer. Recorded spectra were preprocessed before being subjected to multivariate statistical analysis. An initial data exploration using Principal Component Analysis (PCA) revealed a separation of adipose tissue samples between the lower supermarket quality grade and the samples from the local butcher. Moreover, predictive modeling using Partial Least Squares Discriminant Analysis (PLS-DA) resulted in 96.67% classification accuracy for all three sources, demonstrating the suitability of the presented method for intraspecies meat classification and the potential on-site use. Full article

Novel SF₅-bearing maleimide and acrylamide derivatives were synthesised as potential [¹⁸F]radio-prosthetic groups for radiolabelling peptides and proteins. The efficacy of selected prosthetic groups was first assessed through bioconjugation with protected model amino acid derivatives. These reactions were investigated on an analytical scale via LC-MS across a pH range to quantitatively evaluate this prosthetic group’s reactivity and stability. Model bioconjugate reactions were then replicated using analogous para-substituted derivatives to determine the influence of the electronic effects of -SF_5. Finally, the SF₅-bearing prosthetic groups were utilised for bioconjugation with cancer-targeting c-RGD peptides. N-aryl maleimides reacted extremely efficiently with the model amino acid N-acetyl-L-cysteine. The subsequent conjugates were obtained as regio-isomeric mixtures of the corresponding thio-succinamic acids in yields of 80–96%. Monitoring the bioconjugate reaction by LC-MS revealed that ring hydrolysis of the intermediate SF₅–thio-succinimide conjugate occurred instantaneously, an advantageous quality in minimising undesirable thiol exchange reactions with non-targeted cysteine residues. In contrast, N-aryl acrylamides demonstrated poor solubility in semi-aqueous media (<1 mM). In turn, synthetic-scale model bioconjugations with N_α-acetyl-L-lysine were performed in methanol, affording the corresponding acrylamide conjugates in modest to high yield (58–89%). Including electron-deficient, fluorinated prosthetic groups for bioconjugation will broaden their applicability within the fields of ¹⁹F-MRI and PET imaging. Full article

The study of the surface thermodynamic properties of solid materials is primordial for the determination of the dispersive surface energy, polar enthalpy of adsorption and Lewis’s acid base properties of solid particles. The inverse gas chromatography technique (IGC) at infinite dilution is the best surface technique for the determination of the surface physicochemical properties of materials. (1) Background: This paper was devoted to studying the surface properties of solid materials, such as alumina, titania and silica particles, using the IGC technique. (2) Methods: Different methods and molecular models, such as the spherical, cylindrical, Van der Waals, Redlich–Kwong, Kiselev and geometric models, were used to determine the London dispersive surface energy of solid surfaces. The Hamieh model was also used and highlighted the thermal effect on the surface area of solvents. (3) Results: The variations of the dispersive surface energy and the free energy of adsorption were determined for solid particles as a function of the temperature, as well as their Lewis’s acid base constants. Alumina surfaces were proved to exhibit a strong Lewis amphoteric character three times more basic than acidic, titanium dioxide more strongly basic than acidic and silica surface exhibited the stronger acidity. (4) Conclusions: The new methodology, based on the Hamieh model, gave the more accurate results of the physicochemical properties of the particle surfaces. Full article

Among bryophytes, the Plagiochila genus represents a large group of leafy liverworts with over 500 species. Plagiochilins A to X are sesquiterpenoids isolated from Plagiochila species. The lead compound plagiochilin A (Plg-A), endowed with anticancer and antiparasitic properties, has been characterized as a potent mitosis inhibitor, acting selectively at the late stage of cytokinesis termed abscission. The compound perturbs the dynamics of microtubules, blocking cell cycle progression and triggering the death of malignant cells. Based on the compound’s mechanism of action and by analogy with other natural products bearing a dihydro-pyrone moiety, we postulated that Plg-A could bind to the pironetin site of α-tubulin. A molecular docking analysis was performed to compare the bindings of all 24 plagiochilins to α-tubulin and to establish structure–binding relationships. The identification of Plg-E and Plg-G as the best binders in the series highlighted the importance of the C13-OH or C=O group for α-tubulin recognition. This observation led to the testing of the natural-product ester plagiochilin A-15-yl n-octanoate and the corresponding alcohol (Plg-OH), both identified as robust α-tubulin binders. The study provides a rationale to potentially explain the mechanism of action of Plg-A and to guide the design of new derivatives. Full article

Fruits undergo numerous chemical, physical, and microbiological changes during storage that shorten their postharvest life, reducing shelf-life and boosting food loss. Food quality and safety are seriously threatened by postharvest infections, one of the factors behind postharvest deterioration and mycotoxin contamination in fruits. The control of postharvest deterioration is a big concern because there are few management methods available. Several attempts have been undertaken to prevent the microbial degradation of fresh food at the postharvest stage without using synthetic fungicides, which are dangerous for the environment and people’s health. A good substitute for synthetic fungicides among them is the use of natural plant compounds, such as essential oils included or not included in the edible coatings. This review’s aim was to collect information from the scientific literature on the biological activity of essential oil, with or without edible coatings, against pathogens that cause the postharvest spoilage of many fruit belonging to Rosaceae family in order to develop appropriate substitute tactics for synthetic fungicides in the treatment of postharvest fruit diseases. Advances and obstacles surrounding emerging methods that may be useful for enhancing the effectiveness and dependability of essential oils were evaluated. Full article