Citric Acid Research Articles

Assessment of Wine Quality, Traceability and Detection of Grapes Wine, Detection of Harmful Substances in Alcohol and Liquor Composition Analysis

Abstract: Wine production is the result of the interaction between various strains and grapes, and its good quality is also affected by many factors. Aureobasidium, Cladosporium, Candida, Filobasidium, Hanseniaspora, Hannaella, Saccharomyces, Wickerhamomyce, Alternaria, Starmerella, Acetobacter, Papiliotrema, Bradyrhizobium, Leuconostoclia, Gluconobacter, Comamonas, and Massilia, are significantly correlated with changes of physiological properties and volatile compounds. Phenolic compounds, shortened as phenolics, are a vital parameter to the quality of wine, and wine phenolics include two main families: non-flavonoids, which consist of hydroxybenzoic acids (HBAs), hydroxycinnamic acids (HCAs), and stilbenes, and flavonoids, comprising flavonols, flavan-3-ols, and anthocyanins. Wine quality is determined by either sensory tests or physicochemical tests, and the latter analyse the wine’s chemical parameters such as sugar, pH, and alcohol level. The most important constituents found in wine are Terpenes; Aldehydes, Pyrazines, Esters, Ketones and diketones, Mercaptans, and Lactones. In wine quality analysis, the most chief variables are volatile acidity, alcohol, sulphates, citric acid, density, total sulfur dioxide, chlorides, pH, fixed acidity, free sulfur dioxide, and residual sugar. Some classifiers utilized for wine quality prediction in machine learning are: k-Nearest Neighbor (KNN), Random Forest, Decision Tree, Support Vector Machines, Linear Regression, Stochastic Gradient Descent, Artificial Neural Networks (ANN), and Naive Bayes. This article is aimed to review wine quality parameters, detection and traceability of wine, and detection of harmful substances in alcohol and liquor composition analysis.

Citric Acid: A Nexus Between Cellular Mechanisms and Biomaterial Innovations.

Citrate-based biodegradable polymers have emerged as a distinctive biomaterial platform with tremendous potential for diverse medical applications. By harnessing their versatile chemistry, these polymers exhibit a wide range of material and bioactive properties, enabling them to regulate cell metabolism and stem cell differentiation through energy metabolism, metabonegenesis, angiogenesis, and immunomodulation. Moreover, the recent US Food and Drug Administration (FDA) clearance of the biodegradable poly(octamethylene citrate) (POC)/hydroxyapatite-based orthopedic fixation devices represents a translational research milestone for biomaterial science. POC joins a short list of biodegradable synthetic polymers that have ever been authorized by the FDA for use in humans. The clinical success of POC has sparked enthusiasm and accelerated the development of next-generation citrate-based biomaterials. This review presents a comprehensive, forward-thinking discussion on the pivotal role of citrate chemistry and metabolism in various tissue regeneration and on the development of functional citrate-based metabotissugenic biomaterials for regenerative engineering applications.

Differential analysis of aqueous humor metabolomics between presenile cataract and senile cataract

Objective: To explore the differences in metabolites and metabolic pathways in the aqueous humor between patients with presenile cataracts and senile cataracts. Methods: This metabolomic study was conducted at Tianjin Medical University Eye Hospital from August 2020 to September 2022. Eight patients with presenile cataracts (8 eyes) and 8 patients with senile cataracts (9 eyes) were included. Data were collected, including age, gender, preoperative uncorrected visual acuity, intraocular pressure, lens dysfunction index, and axial length. Aqueous humor and anterior capsule tissue samples were obtained during cataract surgery. Metabolites in the aqueous humor were detected using Liquid Chromatography-Mass Spectrometry in a non-targeted approach. The principal component analysis, differential analysis, clustering analysis, and correlation analysis were performed to identify differentially expressed metabolites. These metabolites were ranked based on the fold change (FC). The receiver operating characteristic (ROC) curve analysis and metabolic enrichment analysis were used to identify differential pathways and potential biomarkers for presenile cataracts. Immunohistochemistry was conducted on anterior capsule tissues, and pyruvate levels were measured by colorimetry to validate metabolomic results. Results: Patients with presenile cataracts included 7 males and 1 female, with a mean age of (37.50±4.90) years. Patients with senile cataracts were 7 males and 1 female, with a mean age of (73.44±5.22) years. Except for age, there were no significant differences in baseline data (P>0.05). A total of 347 differential metabolites were identified, 10 of which were potential biomarkers for presenile cataract according to the ROC curve analysis (all P<0.05), including propoxycaine (log2FC=7.26), 2-methyl-2, 3, 4, 5-tetrahydro-1, 5-benzodiazepine-4-ketone (log2FC=6.35), l-pyroglutamic acid (log2FC=-1.72), leanly-proline (log2FC=-0.77), and choline (log2FC=-0.56) in the positive ion mode, and N-phenylacetyl glutamine (log2FC=-1.84), pyruvate (log2FC=1.07), ascorbic acid (log2FC=0.92), pseudouracil nucleoside (log2FC=-0.68), and palmitic acid (log2FC=-0.51) in the negative ion mode. The metabolic enrichment analysis identified 72 differential pathways (32 cationic and 40 anionic), with significant differences in glutathione metabolism, cysteine and methionine metabolism, glycolysis or gluconeogenesis, pyruvate metabolism, and the citric acid cycle (P<0.05). The experimental validation showed reduced lactate dehydrogenase and increased pyruvate levels in patients with presenile cataracts (P<0.05). Conclusions: Pyruvate and nine other metabolites may serve as potential biomarkers for presenile cataracts. Pathways involving glutathione metabolism, cysteine and methionine metabolism, glycolysis or gluconeogenesis, pyruvate metabolism, and the citric acid cycle are notably dysregulated in patients with presenile cataracts.

One‐Pot Synthesis of Orange Emissive Carbon Dots Specific for Staining of Mitochondria in both Cancer and Non‐Cancer Cells

AbstractMitochondria are recognized as essential organelles that form a dynamic network responsible for energy production, calcium homeostasis, and cell signalling for cell metabolism. Dysfunction in mitochondria results in many diseases, such as Alzheimer's, Muscular dystrophy, Diabetes, and Parkinson's. As a result, it is of great significance to directly visualize mitochondria inside cellular environment for therapeutic target. Carbon dots (CDs) are one of the probes with low toxicity and high biocompatibility that have been utilized for mitochondrial visualization. However, till date, CDs are synthesized using multi‐step synthesis and most of them emit in the blue to green region thus limiting their application in bioimaging. Herein, we synthesized orange emissive mitochondria‐specific CDs via a one‐pot method using 3‐(carboxypropyl) triphenylphosphonium bromide (TPP) and citric acid as precursors. Synthesized CDs have excellent photoluminescence properties to stain and image mitochondria in different cancerous and non‐cancerous mammalian cells.

Comparative Analysis of Nickel Adsorption by Natural Sisal Fiber and Treated with Citric Acid

Introduction: Removing nickel from wastewater is complex and costly, requiring research into alternatives with technical and economic solutions. An alternative would be the use of plant biomass. In the Northeast region of Brazil, one of these alternatives, with a large cultivation area, is sisal (Agave Sisaliana), which may have greater yields for this purpose through surface chemical treatment with citric acid, which inserts carboxylic groups into the structure of the plant fiber. Thus, the objective was to analyze the ability to remove nickel in solution by sisal fibers. Methodology: For this purpose, part of the sisal fibers was cut into 0.5 cm, washed and dried; initially treated with NaOH (0.1 mol/L); washed with distilled water and treated with citric acid (1.2 mol/L). The fibers were identified by FTIR; XRD; XRF and SEM. Adsorption tests were carried out with nickel solution for the parameters: kinetics, balance, influence of pH and adsorbent mass. Results: The XRF analysis demonstrated a greater presence of NiO adhered to the treated fiber (55.74%); FTIR confirmed the presence of non-ionized carbonyl in the region from 1700 to 1750 cm-1; the adsorption kinetic test demonstrated greater effectiveness of the treated fiber &gt; 80%; an ideal adsorbent mass was observed to be 0.1g; the ideal pH for removal was 5.0 while the equilibrium test has the best Languimuir isotherm, the uncontrolled fiber obtained R2 = 0.9810 and the controlled fiber R2 = 0.9643. Conclusion: Therefore, it was observed that the treatment of sisal fiber with citric acid increases the removal efficiency of nickel ion in aqueous solution, presenting itself as a low-cost and widely available material.

Facile Green Synthesis of Zingerone Based Tissue‐Like Biodegradable Polyester with Shape‐Memory Features for Regenerative Medicine

AbstractThe abundance of plants as a renewable bioresource has captured the significant attention of researchers, driving them to explore new biodegradable polymeric materials. However, there are still many biobased materials with untapped potential, offering opportunities to synthesize novel biodegradable polymers with multifunctional properties. This work provides a unique solvent and catalyst‐free melt polycondensation process to prepare a series of polyesters using zingerol (Zing‐OH), a reduced form of zingerone, as a primary component for the first time. Briefly, Zing‐OH (a ginger‐based component) is employed in conjunction with a variety of renewable resources, such as citric acid (CA), sebacic acid (SA), and xylitol (Xy), to synthesize multifunctional soft tissue‐like ZCSX polyesters. Fourier‐transform infrared (FTIR) and 1H‐nuclear magnetic resonance (NMR) spectroscopy are used to validate the synthesis of the polyesters, while thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM) are employed to investigate their physicochemical properties. Moreover, the synthesized polyester's thermal, mechanical, and biodegradation properties can be fine‐tuned by simply varying the Zing‐OH feed ratio. The mechanical properties of the synthesized polymer resemble various human tissues, including the liver, uterus, bladder, breast, and temporal and nasal cartilage. This suggests that the synthesized polyesters can potentially be useful in tissue engineering applications. Furthermore, the polyester demonstrated exceptional recovery responses and good shape memory behavior at ambient body temperature. Additionally, as observed from Alamar blue, live/dead assays, and time‐dependent in vitro wound images, the synthesized polyester demonstrated antibacterial activity, good in vitro cytocompatibility, cell proliferation, and wound healing capabilities against mouse fibroblast cells (NIH/3T3). The developed biocompatible polyester also exhibits excellent hemocompatibility for human blood, indicating its potential use in the field of regenerative medicine.

Combination of Bacillus tequilensis with difenoconazole to control pear black spot and the related synergistic mechanism.

Pear black spot (PBS) is caused by Alternaria alternata and causes severe damage worldwide. It is particularly important to screen for synergistic fungicide combinations to address issues associated with the low efficacy of biocontrol agents, high dosage requirements and poor sustained effectiveness of chemical fungicides. In vitro and in vivo studies were performed to determine the efficacy of a treatment for this important disease. Additionally, transcriptomic and metabolomic analyses were performed to determine the main molecular and biochemical mechanisms involved in the interaction. Bacillus tequilensis 2_2a has a significant synergistic effect with difenoconazole, causing hyphal entanglement and spore lysis and inhibiting the formation of PBS lesions in vitro. In the field, the control effect of the combination was greater than 95%. The pathways associated with the synergistic effect on the mycelia of A. alternata were divided into two main types: one included glycolysis, oxidative phosphorylation, and MAPK signal transduction, while the other included glycolysis, the TCA cycle, coenzyme A biosynthesis, sterol synthesis, and fatty acid degradation. Both types of pathways jointly affect the cell cycle. The main functions of the key genes and metabolites that have been verified as being affected are glucose synthesis and oxidative respiration, as well as citric acid synthesis, acetyl-CoA synthesis, and sterol synthesis. Both functions involve intracellular pyridine nucleotide metabolism and adenine nucleotide transformation. This study helps to reveal the synergistic mechanisms underlying the combined efficacy of biological and chemical agents, providing a scientific basis for field applications.

DarA-the central processing unit for the integration of osmotic with potassium and amino acid homeostasis in Bacillus subtilis.

Cyclic di-adenosine monophosphate (c-di-AMP) is a second messenger involved in diverse metabolic processes including osmolyte uptake, cell wall homeostasis, as well as antibiotic and heat resistance. This study investigates the role of the c-di-AMP receptor protein DarA in the osmotic stress response in Bacillus subtilis. Through a series of experiments, we demonstrate that DarA plays a central role in the cellular response to osmotic fluctuations. Our findings show that DarA becomes essential under extreme potassium limitation as well as upon salt stress, highlighting its significance in mediating osmotic stress adaptation. Suppressor screens with darA mutants reveal compensatory mechanisms involving the accumulation of osmoprotectants, particularly potassium and citrulline. Mutations affecting various metabolic pathways, including the citric acid cycle as well as glutamate and arginine biosynthesis, indicate a complex interplay between the osmotic stress response and metabolic regulation. In addition, the growth defects of the darA mutant during potassium starvation and salt stress in a strain lacking the high-affinity potassium uptake systems KimA and KtrAB can be rescued by increased affinity of the remaining potassium channel KtrCD or by increased expression of ktrD, thus resulting in increased potassium uptake. Finally, the darA mutant can respond to salt stress by the increased expression of MleN , which can export sodium ions.IMPORTANCEEnvironmental bacteria are exposed to rapidly changing osmotic conditions making an effective adaptation to these changes crucial for the survival of the cells. In Gram-positive bacteria, the second messenger cyclic di-AMP plays a key role in this adaptation by controlling (i) the influx of physiologically compatible organic osmolytes and (ii) the biosynthesis of such osmolytes. In several bacteria, cyclic di-adenosine monophosphate (c-di-AMP) can bind to a signal transduction protein, called DarA, in Bacillus subtilis. So far, no function for DarA has been discovered in any organism. We have identified osmotically challenging conditions that make DarA essential and have identified suppressor mutations that help the bacteria to adapt to those conditions. Our results indicate that DarA is a central component in the integration of osmotic stress with the synthesis of compatible amino acid osmolytes and with the homeostasis of potassium, the first response to osmotic stress.

Biomarkers of the main nutritional components in purple rice during five successive grain filling stages

Differences in main nutritional components in relation to biomarkers of metabolites in purple rice grains at different fillings stages have not been determined previously. This study measured the contents of amino acids, several nutritional indicators, and mineral elements in purple rice grains at five stages following the filling stage. The results revealed that the amino acid, ascorbic acid, total sugar, carotenoid, vitamin B9, cyanidin-3-O-glucoside, peonidin 3-glucoside and seven minerals were highest in the final stage of grain filling. Citric acid, L-isoleucine, trigonelline, and L-glutamate are key metabolites in the metabolic pathway and exhibit strong correlations with various nutritional indicators. Hence, this research preliminarily suggested that trigonelline, L-isoleucine, L-glutamate, and citric acid could be potential biomarkers of nutritional components in purple rice grains during various postfilling stages.

The effect of washing for the shelf-life parameters of spinach (Spinacia oleracea L.)

Spinach is a very popular green leafy vegetable because of its versatile usage and beneficial for the health. However, spinach may contain several pathogen bacteria: Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Citrobacter spp., Shigella spp. and Listeria monocytogenes, which can cause several serious health problems. This study investigates the effects of washing with citric acid for the shelf-life parameters of spinach in comparison to the effect of washing with water and control. Washing of spinach with 0.5% citric acid solution decreased the elasticity of the spinach leaves, as well as the chlorophyll content. On the other hand, the total plate count, as well as the yeast and mold count could be decreased with this treatment, but difference was not detectable at the forth storage day. The fecal indicator E. coli did not change, indicating washing was not effective in this case. Further optimisation of treatment and storage conditions may decrease microbial risk of fresh spinach consumption without decreasing its sensory quality.

A Comparative Analysis of the Interaction between Donepezil and Albumin with and Without a ZnO/Chitosan Quantum Dot Nanocomposite

AbstractIn this study, a nanocomposite of zinc oxide (ZnO) nanoparticles and chitosan‐based carbon quantum dots (ZnO/chQDs) in the presence of bovine serum albumin (BSA) as a promising drug carrier candidate was synthesized and characterized. For this purpose, chitosan and citric acid were used for the synthesis of chQDs and donepezil (DNP) was selected as a model drug. The BSA binding properties of DNP were analyzed by FT‐IR and UV‐Vis techniques, electrochemical methods and molecular docking in the absence and presence of ZnO/chQDs. The thermodynamic parameters and binding constants of DNP with BSA were also evaluated by these methods. The changes in the structural properties of BSA in the presence of DNP, ZnO/chQDs and ZnO/chQDs‐DNP were monitored by ATR‐FTIR spectroscopy. Cyclic and differential pulse voltammetric techniques and electrochemical impedance spectroscopy were applied to investigate the interactions, using methylene blue in electrolyte solution as redox probe, and its redox behaviour was observed to explore the interactions. Molecular docking was carried out on the interaction of DNP with BSA in the absence and presence of the synthesized ZnO/chQDs, and the results were compared with those of the experimental observations. The experimental results were confirmed by molecular docking studies.

Process optimization for the removal of sodium diclofenac from water using a green polymeric membrane

New polymeric membranes for water treatment have been regularly developed and reported by the scientific community; however, process optimization based on the application purpose is necessary to achieve the best performance. In this work, a previously developed “green” polymeric membrane was employed to investigate the influence of process parameters on the removal of sodium diclofenac (DCF) from water. The “green” classification relies on the membrane components (poly(vinyl alcohol) – PVA, citric acid, glycerol, and green synthesized silver nanoparticles) and the mild conditions for its preparation. The parameters studied were the compaction and operational pressure (1.0 – 5.0 bar), feed temperature (10 – 25 °C), DCF concentration (0.002 – 0.010 g L−1), and feed pH (4.0 – 10.0). The results showed a positive influence of pressure on DCF removal (from 54 % to 75 %, within a range of 1.0–5.0 bar) due to the PVA structure densification, as well as the temperature (from 61 % to 82 %, within a range of 10–25 °C) because of the increased water affinity. The DCF concentration influenced the absorption of DCF into the membrane, reaching the maximum of 73 % of DCF removal at 0.007 – 0.010 g L−1. The feed pH determined the mechanism of removal but had a minor influence on the final performance (from 73 % of DCF removal at acidic pH to 77 % at alkaline conditions). The optimized conditions of 5 bar, 25 °C, 0.008 g L−1 DCF, and pH ∼5.75 promoted a permeability of 0.024 L m−2 h−1 bar−1 with 80 % DCF removal. This performance is comparable to that observed for commercial nanofiltration membranes but offers the advantage of a membrane fabricated and operated using a sustainable approach.

Tuning the composition of CuO/Cu2O composite powders via solution combustion method for supercapacitor application

In this work, the solution combustion synthesis method was implemented as a facile and in-situ procedure to adjust the composition of CuO/Cu2O composite by controlling the amounts of citric acid as fuel. Furthermore, the role of the Cu2O phase on the electrochemical properties was evaluated by preparation the single-phase CuO powders through calcination the CuO/Cu2O composite powders. The structural and microstructural results have shown that the synergic effects of Cu2O and CuO increased the electrochemical performance, including specific capacitance of 842 Fg−1 at 1 Ag−1 and high rate capability of 88 % by increasing the current density to 5 Ag−1. Furthermore, the CuO/Cu2O//activated carbon capacitor exhibited high electrochemical performance, such as an energy density of 27 Wh kg−1 at a power density of 1500 W kg−1 and outstanding cycling stability with 82 % capacitive retention for 2000 charge/discharge cycles, indicating a great potential for the practical application of CuO/Cu2O composite powders.

Relações entre variáveis do maracujá amarelo e roxo

ABSTRACT Brazil is the world’s largest producer of passion fruit, with the species Passiflora edulis Sims (yellow and purple passion fruit) being the most popular commercially. Due to the great economic importance of this culture, seeking high productivity, phytotechnical quality, and maintenance of existing germplasms, among others, it is necessary to carry out studies of the most diverse types of this culture. In this crop, the use of multivariate techniques has increasingly driven studies on genetic differences between passion fruit species. Therefore, this research aimed to identify the variables that deserve greater emphasis in experiments with two commercial species of Passiflora: Passiflora edulis Sims f. edulis (purple passion fruit) and Passiflora edulis Sims (yellow passion fruit), verifying if the species differ from each other. For this purpose, principal component analysis, multivariate analysis of variance (MANOVA), and Hotelling’s T2 test were performed. The principal component analysis proved to be effective, allowing the removal of five variables for yellow passion fruit and six variables for purple passion fruit and yellow passion fruit present contrasting differences between them, being the explanatory variables for the purple passion fruit the external and internal color and for the yellow passion fruit length, diameter, and citric acid.

Carbon-dot/attapulgite composite sonocatalytic towards efficient indigo-containing wastewater degradation based on the cavitation mechanism

Catalytic degradation is an effective method to treat indigo carmine (IC) in wastewater, while high-performance catalyst materials need to be explored. Herein, a facile “spot-heating” synthesis method was employed, whereby the carbon dots (CDs) sonosensitizer was loaded onto the surface of attapulgite (ATP) with ultrasonic cavitation effect, resulting in a composite sonosensitizer ec-CDs/ATP (where ec-CDs represent CDs prepared from ethanol (e) and citric acid (c)). ATP served as a good carrier promotes uniform dispersion of CDs. Benefiting from the large specific surface area, more active sites on the surface of ec-CDs/ATP were exposed, which promotes efficient degradation performance for IC, with a 20 % improvement in performance compared to the reported pure CDs or composite CDs photocatalysts (Bi2O3/dots, Cl-dots). The selective deactivation reactions and relative characterizations further verify that the catalytic process is compatible with the sonocatalytic mechanism originating from the fracture of surface oxygen-containing groups. Importantly, ec-CDs/ATP with a small mass of CDs loading achieves the same catalytic performance as a large mass of pure CDs. This research innovatively presents a simple synthesis method of a composite CDs sonosensitizer and explores its mechanism of degradation, thus pointing the way to the design of multifunctional sonocatalysts for the degradation of IC in wastewater.

Investigation of the luminescence mechanism of multi-color nitrogen-doped carbon quantum dots and their application in the detection of Fe3+

This study reports the successful preparation of nitrogen-doped carbon quantum dots (N-CQDs) with a quantum yield of 15 % utilizing the hydrothermal method. Citric acid was employed as the carbon source, while 1,3-Diamino-2-propanol was utilized as the dopant. It was discovered that the emission of synthesized N-CQDs was dependent on concentration and excitation. By altering the N-CQDs concentration, the fluorescence emission peak was shifted from 453 to 574 nm, causing the emission to transition from blue to orange. The presence of multiple fluorescence emission centers within N-CQDs was confirmed through two-dimensional fluorescence matrix scanning. As the concentration of N-CQDs increased, the distance between these centers decreased, ultimately leading to aggregation. The energy or electrons were transferred as a result of the surface functional groups' interaction, which ultimately causes the fluorescence emission peak to shift to the red. Furthermore, an increase in concentration results in the formation of larger aggregates and larger sp2 carbon domains, ultimately resulting in longer wavelengths. Because of the convenience of use, high sensitivity, and rapid response of the fluorescent probe detection approach, multi-color N-CQDs with tunable concentration were used for the identification of Fe3+, with a 10–200 μM linear detection range and limits of detection (LOD) of 0.56 μM.

The role of Cu doped Ba0.5Sr0.5Fe0.95Zr0.05O3-δ: Local structure distortion, conductivity, and magnetization

The composition Ba0.5Sr0.5Fe1-xCuxZr0.05O3-δ (BSFCZ-x, x = 0–0.20) was successfully synthesized by the sol-gel self-combustion method using citric acid as fuel combustion. Structure, local structure, electrical, and magnetic properties are investigated. The X-ray diffraction revealed the oxides exhibit a cubic structure (Pm3 m), and the lattice parameter increases with x. The X-ray absorption data are analyzed to determine the oxidation state of B site metal transition Fe and Cu through edge-energy E0 evaluation. Fe performs the oxidation states Fe3+ and Fe4+, similarly to Cu2+ and Cu3+. Furthermore, the pre-edge was analyzed to determine the spin state configuration of the 3d subshell. The local lattice distortion was evaluated through EXAFS, resulting in a distorted FeO6 octahedron elongated to the z-axis, inducing the Jahn-Teller effect. The nonstoichiometric δ-value (3-δ) measurement leads to oxygen vacancy VO⦁⦁ defect. The electrical conductivity of semiconducting behavior increases significantly after Cu is dissolved in BSFZ up to 60 S/cm at 500 °C, from initially 5 S/cm. Furthermore, the magnetic properties show a slight magnetic saturation Ms for BSFZ related to the low spin state configuration of Fe 3d subshell, then significantly increased on BSFCZ samples due to Cu provoking spin state dragged partly to high spin state configuration.

Modification and characterization of a novel and fluorine-free cellulose nanofiber with hydrophobic and oleophobic properties

In this study, a brand-new, easy, and environmentally friendly approach for chemically functionalizing 2,2,6,6-tetramethylpiperidinyloxyl radical (TEMPO)-oxidized cellulose nanofiber (TOCNF) to produce modified cellulose nanofiber (octadecylamine-citric acid-CNF) was proposed. Effects of octadecylamine (ODA)/TOCNF mass ratio on the chemical structure, morphology, surface hydrophobicity and oleophobicity were studied. According to Fourier transform infrared spectroscopy (FTIR) analysis, ODA was successfully grafted onto the TOCNF by simple citric acid (CA) esterification and amidation reactions. Scanning electron microscopy (SEM) showed that a new rough structure was formed on the ODA-CA-CNF surface. The water contact angle (WCA) and the castor oil contact angle (OCA) of the ODA-CA-CNF reached 139.6° and 130.6°, respectively. The high-grafting-amount ODA-CA-CNF was sprayed onto paper, and the OCA reached 118.4°, which indicated good oil-resistance performance. The low-grafting-amount ODA-CNF was applied in a pH-responsive indicator film, exhibiting a colour change in response to the pH level, which can be applied in smart food packaging. The ODA-CA-CNF with excellent water/oil-resistance properties and fluorine-free properties can replace petrochemical materials and can be used in the fields of fluorine-free oil-proof paper.

Đánh giá khả năng ức chế ăn mòn đồng M-1 và nhôm AK-7 của benzotriazol trong dung dịch axit xitric 5%

This paper presents the research results on the corrosion inhibition effect of benzotriazole on copper M-1 and aluminum AK-7 in 5% citric acid solution. Electrochemical test resultsshow that benzotriazole as a good corrosion inhibitors for copper M-1 and aluminum AK-7. The optimal protective concentration of benzotriazole in this condition is 0.5%, at which the protective effect for copper M-1 and aluminum AK-7 is 75.43% and 69.56% respectively. After 2 hours of corrosion test in glassware at 88±2°C by mass loss method with a concentration of 0.5% benzotriazole, the protective effect for copper M-1 and aluminum AK-7 reaches 69.1% and 65.4% respectively.

Evolutionary ecology of denitrifying methanotrophic NC10 bacteria in the deep-sea biosphere.

The NC10 phylum links anaerobic methane oxidation to nitrite denitrification through a unique O2-producing intra-aerobic methanotrophic pathway. Although numerous amplicon-based studies revealed the distribution of this phylum, comprehensive genomic insights and niche characterization in deep-sea environments were still largely unknown. In this study, we extensively surveyed the NC10 bacteria across diverse deep-sea environments, including waters, sediments, cold seeps, biofilms, rocky substrates, and subseafloor aquifers. We then reconstructed and analysed 38 metagenome-assembled genomes (MAGs), and revealed the extensive distribution of NC10 bacteria and their intense selective pressure in these harsh environments. Isotopic analyses combined with gene expression profiling confirmed that active nitrite-dependent anaerobic methane oxidation (n-DAMO) occurs within deep-sea sediments. In addition, the identification of the Wood-Ljungdahl (WL) and 3-hydroxypropionate/4-hydroxybutyrat (3HB/4HP) pathways in these MAGs suggests their capability for carbon fixation as chemoautotrophs in these deep-sea environments. Indeed, we found that for their survival in the oligotrophic deep-sea biosphere, NC10 bacteria encode two branches of the WL pathway, utilizing acetyl-CoA from the carbonyl branch for citric acid cycle-based energy production and methane from the methyl branch for n-DAMO. The observed low ratios of non-synonymous substitutions to synonymous substitutions (pN/pS) in n-DAMO-related genes across these habitats suggest a pronounced purifying selection that is critical for the survival of NC10 bacteria in oligotrophic deep-sea environments. These findings not only advance our understanding of the evolutionary adaptations of NC10 bacteria but also underscore the intricate coupling between the carbon and nitrogen cycles within deep-sea ecosystems, driven by this bacterial phylum.