Search Results (188)

Carbon dioxide (CO₂) capture using alkanolamines remains the most mature technology, yet faces challenges including solvent loss, high regeneration energy and equipment corrosion. Ionic liquids (ILs) are proposed as alternatives, but their high viscosity and production costs hinder industrial use. Thus, blending ILs with amines offers a promising approach. This work presents new experimental data for aqueous blends of 1-butyl-3-methylimidazolium hydrogen sulfate, $\left[\mathrm{B}\mathrm{m}\mathrm{i}{\mathrm{m}}^{+}\right]\left[\mathrm{H}\mathrm{S}{\mathrm{O}}_4^{-}\right],$ with 2-amino-2-methyl-1-propanol (AMP) and 3-(methylamino)propylamine (MAPA) and for choline glycine, $\left[\mathrm{C}{\mathrm{h}}^{+}\right]\left[\mathrm{G}\mathrm{l}{\mathrm{y}}^{-}\right]$, with AMP, modeled using the modified Kent–Eisenberg approach. It was shown that substituting a portion of the amine with $\left[\mathrm{B}\mathrm{m}\mathrm{i}{\mathrm{m}}^{+}\right]\left[\mathrm{H}\mathrm{S}{\mathrm{O}}_4^{-}\right]$ reduces CO₂ uptake per mole of amine due to the lower solution’s basicity, despite the added sites for physical absorption. In contrast, the replacement of an amine portion with $\left[\mathrm{C}{\mathrm{h}}^{+}\right]\left[\mathrm{G}\mathrm{l}{\mathrm{y}}^{-}\right]$ enhances both physical and chemical interactions, leading to increased CO₂ solubility per mole of amine. Finally, replacing a small portion of water with $\left[\mathrm{C}{\mathrm{h}}^{+}\right]\left[\mathrm{G}\mathrm{l}{\mathrm{y}}^{-}\right]$ does not significantly alter the bulk CO₂ solubility (moles of CO₂ per kg of solvent) but lowers the solvent’s vapor pressure. Given the non-toxic nature of $\left[\mathrm{C}{\mathrm{h}}^{+}\right]\left[\mathrm{G}\mathrm{l}{\mathrm{y}}^{-}\right]$, the resulting solvent poses no added environmental risk. Model predictions agree well with experimental data (deviations of 2.0–11.6%) and indicate low unreacted amine content at CO₂ partial pressures of 1–10 kPa for carbamate-forming amines, i.e., $\left[\mathrm{G}\mathrm{l}{\mathrm{y}}^{-}\right]$, and MAPA. Consequently, at higher CO₂ partial pressures, the solubility increases due to carbamate hydrolysis and molecular CO₂ dissolution. Full article

Metal–organic frameworks (MOFs) are materials with extremely valuable properties. The latter depend largely on the ligand used; therefore, the design of new organic linkers is a priority task today. A series of s-triazines possessing variable heteroatom-bridged identical substituents, useful ligands for the synthesis of MOFs, is obtained in good to excellent yields. The problem of obtaining free carboxyl groups without forming salts with nitrogen atoms is solved. The products are characterized by NMR spectra and single crystal XRD of selected samples. Unexpected O-triazine bond cleavage under basic hydrolysis conditions is observed. Full article

In recent years, efforts have focused on developing repairable, malleable, and recyclable thermoset materials to reduce the growing volume of polymer waste and extend the lifetime of existing polymeric materials. Specifically, associative covalent adaptable networks (CANs), also known as vitrimers, have received considerable attention. In this work, photopolymerizable vitrimers were prepared by combining crosslinkers containing β-amino esters in their structure with hydroxylated acrylate or methacrylate monomers, with the aim of reprocessing these materials through the activation of transesterification reactions. The network design and photopolymerization conditions were optimized to ensure the successful formation of the vitrimers. Tunable mechanical and thermal properties were achieved by varying their chemical composition. Furthermore, the reprocessing ability of these materials was confirmed through thermal treatments. Additionally, these vitrimers exhibited the ability to undergo hydrolysis in basic aqueous media, providing an alternative pathway for recycling. Full article

Macroalgae are often used to produce sodium alginate, but their by-products have not been fully utilized. This study aimed to optimize the extraction of bound polyphenols (BPs) from Macrocystis pyrifera (L.) residues, analyze the composition of free polyphenols (FPs) and BPs, and evaluate their antioxidant activities and ability to inhibit glycosidase activity. The optimal conditions for extracting BPs achieved by the response surface method were as follows: 50 °C, a solid–liquid ratio of 1:50, an alkaline hydrolysis time of 2.38 h, and a NaOH concentration of 8 mol/L. Polyphenol content determination results indicated that FPs had significantly higher total polyphenols (13.02 ± 0.05 μg GAE/mg) and phlorotannin (3.44 ± 0.04 μg PE/mg) than BPs (6.57 ± 0.07 μg GAE/mg and 1.32 ± 0.20 μg PE/mg). HPLC/ESI-QTOF-MS showed distinct profiles: FPs had one polyhydroxy phenol, nine flavonoids, and four additional compounds, whereas BPs had five flavonoids and four other compounds. Antioxidant activity was found to be higher in FPs than in BPs (DPPH: 3.03 vs. 1.79 μg TE/mg; FRAP: 19.40 vs. 7.43 μg TE/mg). Furthermore, FPs exhibited 4.59- and 11-fold higher inhibition capacity toward α-amylase and α-glucosidase, respectively, compared to BPs. The results provide valuable basic data for the application of macroalgae residues in the marine biological industry and reveal their potential hypoglycemic ability. Full article

The global transition toward plant-based diets has intensified the search for sustainable protein alternatives, positioning hemp-based meat analogs (HBMAs) as a promising solution due to their exceptional nutritional profile and environmental benefits. This comprehensive review critically examines hemp protein research, focusing on extraction technologies, nutritional excellence, functional innovation, and sustainable processing approaches for meat analog development. Hemp seeds contain 25–30% protein, primarily consisting of highly digestible edestin and albumin proteins that provide a complete amino acid profile comparable to soy and animal proteins. The protein exhibits superior digestibility (>88%) and generates bioactive peptides with demonstrated antioxidant, antihypertensive, and anti-inflammatory properties, offering significant health benefits beyond basic nutrition. Comparative analysis reveals that while alkaline extraction-isoelectric precipitation remains the industrial standard due to cost-effectiveness ($2.50–3.20 kg⁻¹), enzymatic extraction and ultrasound-assisted methods deliver superior functional properties despite higher costs. Hemp protein demonstrates moderate solubility and good emulsifying properties, though its gelation capacity requires optimization through enzymatic hydrolysis, high-pressure processing, or strategic blending with complementary proteins. Processing innovations, particularly high-moisture extrusion combined with protein blending strategies, enable fibrous structures closely mimicking conventional meat texture. Hemp protein can replace up to 60% of soy protein in high-moisture meat analogs, with formulations incorporating wheat gluten or chickpea protein showing superior textural attributes. Despite advantages in nutritional density, sustainability, and functional versatility, HBMAs face challenges including sensory limitations, regulatory barriers, and production scaling requirements. Hemp cultivation demonstrates 40–50% lower carbon footprint and water usage compared with conventional protein sources. Future research directions emphasize techniques and action processes, developing novel protein modification techniques, and addressing consumer acceptance through improved sensory properties for successful market adoption. Full article

This work mainly explores whether the solubility product principle has a guiding role in regulating the composition of micro-arc oxidation (MAO) coatings. The MAO process was conducted on AZ31 Mg alloy in silicate electrolyte. Varying amounts of Potassium fluoride (KF) and Ammonium fluoride (NH₄F) were separately added to the basic electrolyte to regulate the OH⁻ and F⁻ contents in the electrolyte. The microstructure, phase composition and corrosion resistance of the MAO coatings prepared in different electrolytes were analyzed. Results showed that regardless of KF content, MgO was the main component for the MAO coatings obtained in electrolytes with KF. This was because the addition of KF not only elevated the F⁻ concentration in the electrolyte but also enhanced the OH⁻ concentration as a result of F⁻ hydrolysis. Based on the solubility product constants (Ksp) of MgO and MgF₂, a relatively lower concentration of Mg²⁺ was sufficient for the formation of MgO. Hence, Mg²⁺ consistently exhibited preferential reactivity with OH⁻, leading to the formation of MgO. The findings of the study demonstrated that the presence of KF electrolyte resulted in an enhancement of conductivity and an increase in the concentration of OH⁻. Conversely, the growth rate of the coating was observed to be low, and the coating-forming phases of the coating were identified as MgO and Mg₂SiO₄, and the coating had better corrosion resistance. NH₄F electrolyte with the increase in NH₄F concentration, conductivity decreases and then increases, OH⁻ concentration decreases, the growth rate of the coating is faster, the concentration of F⁻/OH⁻ is higher, the coating-forming phase is transformed into MgF₂, and the corrosion resistance of the coating is reduced. Full article

6-monoacetylmorphine (6-MAM), a primary active metabolite of heroin that reaches the human brain, plays a crucial role in producing heroin-associated physiological and lethal effects. Therefore, 6-MAM has emerged as a key target for alleviating the adverse consequences of heroin abuse. In this study, the proposed 6-MAM hydrolase E. coli aminopeptidase N (eAPN) was recombinantly produced, and its biochemical and functional profiles were investigated. eAPN’s biochemical properties, with respect to pH, metal ions, and temperature, and catalytic functions toward peptidase substrates and 6-MAM were thoroughly examined. Extensive experiments reveal that incorporation of an N-terminal His-tag notably affects eAPN’s aminopeptidase activity. This cost-effective recombinant eAPN exhibits favorable thermostability and optimal activity at pH 7.5. Kinetic analysis toward peptidase substrates reveals that eAPN preferentially cleaves peptides following amino acid residues in the order of Ala > Arg >> Met, Gly > Leu > Pro, indicating a preference for small or basic amino acid residues as substrates. Computational and experimental studies have, for the first time, discovered that eAPN is capable of catalyzing the hydrolysis of heroin and 6-MAM, which has shed light on its functional versatility and potential applications. This work elucidates the biochemical properties of eAPN and expands its catalytic functions, thereby laying the groundwork for a deep understanding and further reengineering of eAPN to enhance its activity toward 6-MAM for heroin detoxification. Full article

The influence of the quantity of silanol in an active silicic acid solution (ASAS) on the growth rate of colloidal silica particles was investigated. The quantity of silanol in the ASAS was controlled by varying the acid concentration as a hydrolysis catalyst for tetramethoxysilane (TMOS). As expected, the particle growth rate was confirmed to be a function of the acid concentration in the water used to prepare the ASAS. In addition, when the entire process was conducted under basic conditions to obtain spherical particles, the initial basicity had a secondary influence on the particle growth rate. When a partial process was conducted under acidic conditions to obtain morphologically modified particles, the low acidity was found to have a secondary influence on the particle growth rate. Furthermore, it was clarified that the relative silica deposition rate based on acid-free ASAS could be predicted by assuming the seed particle size at the time it was determined. Thus, a production control system was established for highly purified colloidal silica using ASAS derived from TMOS. Full article

The influence of pH on silicon dioxide direct bonding is studied, unveiling its role in bonding energy enhancement. We show that the deposition of basic salt or molecules consistently increases the silicon dioxide adherence energy. The underlying mechanisms, including silica hydrolysis and catalysis of siloxane bond formation, are explored. The results offer valuable insights into optimized direct bonding processes for microelectronics and related applications. Full article

γ-amino butyric acid (GABA) is an inhibitory neurotransmitter whose deficiency has been associated with various neurological disorders. However, its low liposolubility limits its use as a supplement. Thus, multiple investigations have focused on searching for lipophilic GABA analogs that can modulate the activity of the GABA_B receptor, which could be associated with the etiology of some central nervous system disorders. The GABA analogs available on the market are Vigabatrin, Gabapentin as well as Pregabalin and Baclofen. In this work, we report on the synthesis of GABA analogs, taking the scaffold of GABA, Pregabalin, and Baclofen as a starting point. The analogs include structural features that could favor the affinity of the molecules for the GABA_B receptor, such as heterocyclic rings in the γ-position and alkyl or p-Cl-phenyl substituents (in analogy to Pregabalin and Baclofen, respectively). These analogs were synthesized by a sequence of reactions involving an N-alkylation, a 1,4-conjugated addition of dialkyl and diarylcuprates and a basic hydrolysis. Furthermore, a computational molecular docking over the GABA_B receptor was performed to evaluate the interaction of each compound in the Baclofen binding site. With this information, we evaluated our compounds as GABA_B agonists through a QSAR analysis. Finally, by means of molecular similarity analysis, and in silico ADME prediction, we support our three best compounds (8a–b, 8d) as potential GABA_B receptor agonists. Full article

In this study, we thoroughly investigated the stability of haloperidol using a comprehensive set of chromatographic and thermal analyses. Various stress conditions were examined, including exposure to oxidizing agents (such as hydrogen peroxide), dry heat, photolytic conditions, and acid and alkaline hydrolysis. Significant degradation was observed in acidic and alkaline environments, leading to the formation of degradation by-products, specifically DPA, DPB, DPC, and DPD for acidic and basic conditions. In contrast, haloperidol demonstrated robust stability under photolytic, oxidative, and dry-heat conditions. For the analysis of the drug and its degradation products, a C-18 column was employed, coupled with a mobile phase consisting of methanol and a phosphate buffer (pH = 9.8) in a 90:10 (v/v) ratio. The analytical method was rigorously validated according to ICH Q2 (R1) guidelines, ensuring its accuracy and reliability. This method exhibited excellent linearity within a concentration range of 1 to 50 µg/mL, with an R² of 0.999. Additionally, this method is applicable to commercial formulations, without the need for prior extraction. LC-MS/MS analysis revealed distinct m/z values and fragmentation spectra corresponding to the degradation products, including an impurity not documented in the European Pharmacopoeia monograph for the drug. Three additional degradation products were identified based on m/z values and base fragments. Thermal analyses, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and differential thermal analysis (DTA), provided further evidence of the active ingredient’s thermal stability, with a melting temperature of approximately 150 °C. These results collectively offer valuable insights into the degradation behavior of haloperidol, providing critical implications for its pharmaceutical quality and integrity under various environmental conditions. Full article

Basic amino acids have emerged as a pivotal area of research in efforts to decrease the sodium content in meat products, primarily due to their ability to enhance flavor, improve taste, and effectively replace sodium salts. This review synthesizes current strategies for sodium reduction in meat products and offers an overview of previous studies examining the role of basic amino acids in such applications, including their impact on sensory attributes and structural alterations. Furthermore, the implications of these strategies on product quality are examined, addressing aspects such as protein hydrolysis, oxidation, color, and textural changes, as well as potential underlying mechanisms. Additionally, future challenges and trends in the utilization of basic amino acids in processed meats are explored. Overall, basic amino acids exhibit significant potential as sodium salt substitutes, particularly at low NaCl concentrations. Their combinations with chloride salts, yeast extracts, and other salts have been explored as alternative sodium reduction strategies. However, challenges remain in their application to meat products, including high production costs, consumer acceptance, and stability during large-scale production. Future research should focus on optimizing the use of basic amino acids, enhancing their economic feasibility, and addressing technical hurdles. Full article

Freshwater fish processing produces 30–70% nutrient-rich by-products, often discarded or undervalued. Grass carp by-products, rich in protein, offer potential as raw materials for fermented seasonings. This study explores the use of these by-products—specifically, minced fish and fish skin—in soybean fermentation to evaluate their effects on the quality of the resulting seasonings. Tetragenococcus halophilus was used as a starter culture alongside food-grade protease to assess their combined impact on the safety and flavor of soy fish paste and soy fish skin paste. The findings revealed that natural fermentation resulted in higher protein hydrolysis in soy fish skin paste compared to soy fish paste. Across all fermentation conditions, amino acid nitrogen levels increased, while total volatile basic nitrogen levels decreased in both pastes, indicating improved quality. Additionally, microbial fermentation significantly reduced biogenic amine content in soy fish paste, enhancing safety. Enzymatic fermentation further enriched the flavor of both pastes by boosting key compounds such as 2-methylbutanal and ethyl acetate. Notably, enzyme-microbe co-fermentation harnessed the strengths of both methods, achieving improved safety and enhanced flavor profiles while elevating overall product quality. These findings suggest a promising way to transform freshwater fish by-products into high-value condiments, advancing sustainable food processing. Full article

This article describes the basics of chemical thermodynamics and its application to the study of plant biomass and its main components, cellulose, hemicelluloses, lignin, etc. The energy potential of various biomass types, as well as biomass-based solid, liquid, and gaseous biofuels, is determined. A method of additive contributions of combustion enthalpies of main components is proposed to calculate the combustion enthalpy of biomass samples. It is also established that the potential of thermal energy of the initial biomass is higher than the energy potential of secondary biofuels released from this biomass. The thermodynamic functions of plant biopolymers are calculated. Moreover, the thermodynamic stability of various crystalline allomorphs of cellulose and amorphous cellulose is studied. The melting enthalpies of crystallites with different types of crystalline structures are estimated. A thermochemical method for determining the degree of crystallinity of cellulose is proposed. The most important biomass components are cellulose and other polysaccharides. The thermodynamics of the enzymatic hydrolysis of polysaccharides and their conversion into glucose are described. In addition, the thermodynamic analysis of the conversion process of glucose into bioethanol is performed. Considerable attention is also paid to the thermochemistry of cellulose alkalization, etherification, and esterification. Full article

Reducing soil tillage with the application of catch-crop green mass as a mulch is a conservation practice that is used in agriculture to improve soil ecosystem functioning. Such a cultivation method enhances soil organic matter quantity and quality through the improvement of soil biological activity and nutrient availability, while reducing soil disturbance. Therefore, a three-year field experiment was conducted in the years 2017–2019 to evaluate the effect of three tillage methods (TMs) (conventional, CT; reduced, RT; and strip tillage, ST) on soil microbial and specific enzyme properties (microbial C and N content, the activity of dehydrogenases—DHA, the rate of fluorescein sodium salt hydrolysis—FDAH, CMC-cellulase—Cel and β-glucosidase—Glu) and certain basic soil properties. The study was performed in a field; it was a one-factor experiment that was carried out in a randomized block design. The soil samples were collected from the upper soil layer five times a year: in April (before the sowing of soybean), May, June, August and September (before soybean harvesting). The tillage methods or sampling dates used had no significant effect on the organic carbon and total nitrogen levels. Most of the C-related properties (the content of microbial biomass and the C-cycling enzymatic activity such as Cel and Glu) and microbial activity bioindicators (DHA activity, FDAH rate) revealed significant seasonal changes, whereby each variable was affected in a different order (e.g., the Cel activity was significantly higher in April and September than in other months—22%, while the DHA activity was significantly higher in June and August compared to other months—18%). RT significantly increased the enzymatic activity as compared to CT and ST, and the difference was between 8 and 33% (with a mean of 18%). The exception was the β-glucosidase activity as determined in 2019, which was significantly higher in the case of CT (1.02 mg pNP kg⁻¹ h⁻¹) and ST than in RT (0.705 mg pNP kg⁻¹ h⁻¹). However, the explanation for such phenomenon could not possibly be based on the available data. Our results suggested that the response of the enzyme activities toward the same factor may be due to the inherent variability in enzyme response associated with the spatial variability in soil properties as well as the properties of the enzyme itself and changes in the periodic occurrence of its substrates in the soil. Generally, the reduced tillage combined with plant residues return could be recommended for enhancing soil health and quality by improving its microbial and enzymatic features. The findings above suggest that a reduced tillage system is an important component of soil management in sustainable agriculture. Full article