Hydrogen Nuclear Magnetic Resonance Research Articles

Evaluation of Modified Asphalt Binders with Soybean Oil-Based Polymers: Preparation Temperature and Rheological Characterization

To investigate the feasibility of bio-based polymers in the modification of base asphalt binder, two soybean oil-based polymers (PAESO) were synthesized from bio-monomers with different functionalities via free radical polymerization. The characterization of both PAESOs was conducted using Hydrogen nuclear magnetic resonance and Gel Permeation Chromatography analyses, the results showed that the bio-monomer with a higher functionality exhibited a stronger tendency towards self-polymerization, resulting in the polymer with a high conversion rate (44.44 %) and a slightly lower molecular weight (14.76 kDa). The optimal mixing temperature for preparing PAESO-modified asphalt binders was determined through Molecular Dynamics (MD) simulation and Laser Scanning Confocal Microscopy. The MD simulation results indicated that PAESO-modified asphalt models had reached the most stable configurations at a mixing temperature of 160 °C, as evidenced by fewer and more homogeneous distributed small bright spots observed in fluorescence images. This suggested that the outstanding compatibility between PAESO and asphalt binders could be obtained at the optimal mixing temperature of 160 °C. Furthermore, the rheological characteristics of asphalt binders modified with PAESO were examined through Dynamic Shear Rheometer and Bending Beam Rheometer tests. The results revealed that PAESO mainly exhibited a softening effect by significantly enhancing the flexibility, stress relaxation, fatigue, and thermal cracking resistance of the base asphalt binders at intermediate and low temperatures. PAESO-L modified asphalt manifested elastic properties akin to those observed in polymer-modified asphalt within the low-frequency and high-temperature domain. Additionally, PAESO derived from monomers with a higher functionality presented notable benefits in enhancing thermal and fatigue cracking resistance than that of PAESO with a lower functionality. These findings provide valuable insights for the preparation and development of bio-polymer additives for use in asphalt materials.

Studies on the SYNTHETIC Method of 2,5-Dihydroxyterephthalaldehyde

2,5-Dihydroxyterephthalendehyde (Dha) can be used as an intermediate in organic chemistry and synthetic materials, which can participate in a variety of chemical reactions. Through these reactions, a variety of valuable compounds can be synthesized. However, the existing synthesis methods are cumbersome, difficult to operate, and have low yields. Referring to the reported Dha synthesis process, we successfully synthesized Dha using inexpensive 1,4-dimethoxybenzene with simple steps. The correct structure was proved by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (1H-NMR) hydrogen spectroscopy, and nuclear magnetic resonance (13C CP-MAS NMR) carbon spectroscopy, which provides a valuable reference for the synthesis of Dha.

Room-temperature stable Perillaldehyde—Natural cyclodextrin inclusion complexes: Preparation, characterization, thermal stability, water solubility, antioxidant activity and slow–release performance

The compound Perillaldehyde (PA) is a bioactive constituent found in natural Perilla oil, exhibiting remarkable antibacterial and antioxidant activity. However, the instability of this compound caused by the easy oxidation of its aldehyde and olefin groups imposes limitations on its extensive applications. Therefore, it is crucial to develop effective strategies for enhancing the stability of PA. This study focuses on utilizing a series of natural cyclodextrins (CDs) to synthesize inclusion complexes (ICs) with PA, aiming to improve water solubility and achieve exceptional stability at room temperature, which is essential for their potential applications in biomedicine or food industries. The hydrophobic cavity of CDs can accommodate the hexatomic ring and hydrophobic chains of PA based on the well-known size-matching effect and hydrophobic interaction, thereby forming stable ICs. Additionally, the hydrophilic outer wall of CDs imparts excellent water solubility to ICs. Phase solubility investigations demonstrate successful construction of α-CD-PA IC and β-CD-PA IC with an inclusion ratio of 1:1. Their respective stability constant (KC) are determined as 342 L/mol and 180 L/mol, indicating superior stability for α-CD-PA IC compared to β-CD-PA IC. Conversely, γ-CD with a larger cavity fails to form a stable inclusion complex with PA due to inadequate size matching. Nuclear Magnetic Resonance Hydrogen Spectroscopy (1H and 2D NMR) studies reveal that PA enters the CDs cavity (α-CD or β-CD) from its wide rim with almost the entire molecule being obliquely embedded within it. Thermogravimetry Analysis (TGA) confirm that after inclusion with CDs, PA exhibits expected stability at 25 ℃. Furthermore, CDs-PA ICs demonstrate significantly improved water solubility compared to pure PA along with enhanced antioxidant activity and slow-release performance, rendering them highly favorable for various applications.

Excess properties and intermolecular interactions of 2-methoxyethanol + ethylenediamine binary system: Density, viscosity, spectral analyses, computational chemistry, and CO2 absorption property

To examine the fundamental physicochemical properties as well as intermolecular interactions for the 2-methoxyethanol (EGME) (1) + ethylenediamine (EDA) (2) binary system, this work systemically measured the density (ρ) and viscosity (η) values of the binary system with various mole ratios at P = 100.5 kPa and T = (298.15–318.15) K with the growth gap of 5 K. The as-measured values of the pure substances were compared with literature data. Multiple semi-empirical formulas were used to fit ρ and η values, and the absolute average deviations (AAD%) were calculated. After that, the excess molar volume (VmE), partial molar volume (V¯), apparent molar volume (Vφ), viscosity deviation (Δη), excess activation of Gibbs free energy (ΔG∗E), and several thermodynamic properties of the binary system were systemically analyzed. According to analysis results, it has been proven that the interaction exists between EGME and EDA molecules. And then, excess properties were fitted to the Redlich-Kister equation using multi-parametric nonlinear regression analyses, and standard deviations (σ) were calculated. In addition, based on various characterization methods including Raman, ultraviolet (UV), and nuclear magnetic resonance hydrogen (1H NMR) spectral analyses and density functional theory (DFT) calculation results, it is demonstrated that there is intermolecular hydrogen bonds in EGME (1) + EDA (2) binary system as the form of –OH⋯NH2–, which was consistent with the existence forms of intermolecular hydrogen bonds in different alcohol-amine systems from references. Finally, CO2 absorption capacity by pure EDA, pure EGME, and the EGME (1) + EDA (2) binary system were severally determined.

Comparative Analysis of Hydrogel Adsorption/Desorption with and without Surfactants.

In this particular study, a hydrogel known as SAP-1 was synthesized through the grafting of acrylic acid-co-acrylamide onto pullulan, resulting in the creation of Pul-g-Poly (acrylic acid-co-acrylamide). Additionally, a sponge hydrogel named SAP-2 was prepared by incorporating the surfactant sodium dodecyl benzene sulfonate (SDBS) into the hydrogel through free radical solution polymerization. To gain further insight into the composition and properties of the hydrogels, various techniques, such as Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H NMR), atomic absorption spectroscopy, and field emission scanning electron microscopy (FE-SEM), were employed. Conversely, the absorption kinetics and the equilibrium capacities of the prepared hydrogels were investigated and analyzed. The outcomes of the investigation indicated that each of the synthesized hydrogels exhibited considerable efficacy as adsorbents for cadmium (II), copper (II), and nickel (II) ions. In particular, SAP-2 gel displayed a remarkable cadmium (II) ion absorption ability, with a rate of 190.72 mg/g. Following closely, SAP-1 gel demonstrated the ability to absorb cadmium (II) ions at a rate of 146.9 mg/g and copper (II) ions at a rate of 154 mg/g. Notably, SAP-2 hydrogel demonstrated the ability to repeat the adsorption-desorption cycles three times for cadmium (II) ions, resulting in absorption capacities of 190.72 mg/g, 100.43 mg/g, and 19.64 mg/g for the first, second, and third cycles, respectively. Thus, based on the abovementioned results, it can be concluded that all the synthesized hydrogels possess promising potential as suitable candidates for the adsorption and desorption of cadmium (II), copper (II), and nickel (II) ions.

Exploring the effects of the dietary fiber compound mediated by a longevity dietary pattern on antioxidation, characteristic bacterial genera, and metabolites based on fecal metabolomics

BackgroundAge-related dysbiosis of the microbiota has been linked to various negative health outcomes. This study aims to investigate the effects of a newly discovered dietary fiber compound (DFC) on aging, intestinal microbiota, and related metabolic processes. The DFC was identified through in vitro fermentation screening experiments, and its dosage and composition were determined based on a longevity dietary pattern.MethodsAged SPF C57BL/6 J mice (65 weeks old) and young mice (8 weeks old) were divided into three groups: a subgroup without dietary fiber (NDF), a low DFC dose subgroup (LDF, 10% DFC), and a high DFC dose subgroup (HDF, 20% DFC). The total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) activity, malondialdehyde (MDA) content, and glutathione peroxidase (GSH-Px) activity in liver and serum samples of the mice were measured according to the manufacturer’s protocol. The expression levels of characteristic bacterial genera and fecal metabolite concentrations in mice were determined using quantitative real-time PCR (qPCR) and nuclear magnetic resonance hydrogen spectroscopy (1H NMR). Metabolomics analysis was further conducted to identify biological functions and potential pathways related to aging.ResultsAfter an 8-weeks dietary intervention, DFC supplementation significantly attenuated age-related weight loss, organ degeneration, and oxidative stress. And promoted the growth of Lactobacillus and Bifidobacterium and inhibited the growth of Escherichia coli (E. coli) and Bacteroides (p < 0.05) in the intestinal tracts of aged mice. Metabolomic analysis identified glycolipid and amino acid metabolic pathway biomarkers associated with aging that were differentially regulated by DFC consumption. Correlation analysis between the identified microbial flora and the biomarkers revealed potential mechanistic links between altered microbial composition and metabolic activity with aging markers.ConclusionsIn conclusion, this study revealed an important mechanism by which DFC consumption impacts healthspan and longevity, shedding light on optimizing dietary fiber or developing fiber-based interventions to improve human health.

Synthesis, Characterization, and Properties of a Novel Hyperbranched Polymers with Polyacrylamide Side Chains.

A novel hyperbranched polymer with polyacrylamide side chains (HAPAM) was synthesized by aqueous solution polymerization using acrylic acid, acrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid, hydrophobic monomer of dimethyl octadecyl ammonium chloride, and the homemade skeleton monomer of modified-M2.0 as raw materials and (NH4)2S2O8-NaHSO3 as initiator. The molecular structure, functional groups, and surface morphology of HAPAM were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, and scanning electron microscopy. It was found that the performance of HAPAM solution was higher than that of ordinary polyacrylamide solution in terms of thickening ability, shearing resistance, thermal endurance, salt-resistance, resistance-coefficient and residual-resistance-coefficient, ability to reduce interfacial tension between polymer solution and crude oil, and oil-displacement-efficiency. In particular, the enhanced oil recovery of the HAPAM solution was 13.03%, and the improvement of shearing resistance and immunity to chromatographic separation were simultaneously achieved by the HAPAM solution. These results indicate that the successful synthesis of the novel HAPAM opens a promising strategy for developing new high-performance oil-displacing polymers.

Construction of a novel flavonol fluorescent probe for copper (II) ion detection and its application in actual samples

Copper is an essential trace element in the human body, and its level is directly related to many diseases. While the source of copper in human body is mainly intake from food, then the detection of copper ions (Cu2+) in food becomes crucial. Here, we synthesized a novel probe (E)-3-hydroxy-2-styryl-4H-benzo[h]chromen-4-one (NSHF) and explored the binding ability of NSHF for Cu2+ using nuclear magnetic resonance hydrogen spectroscopy (1H NMR), high-resolution mass spectrometry (HRMS), Job's plot method and density functional theory (DFT). NSHF shows the advantages of fast response time, good selectivity and high sensitivity for Cu2+. The fluorescence intensity ratio (F/F0) of NSHF shows a good linear relationship with the concentration of Cu2+ and the detection limit is 0.061 μM. NSHF was successfully applied to the detection of Cu2+ in real samples. In addition, a simple and convenient Cu2+ detection platform was constructed by combining NSHF with a smartphone and a UV lamp, which can realize the rapid detection of Cu2+. This work provides an effective tool for the real-time detection of Cu2+.

Determination of pesticide residue in soil samples by molecularly imprinted solid-phase extraction method

Abstract Porous molecularly imprinted polymer (MIP) microspheres were synthesized via iniferter-suspension polymerization method, employing lenacil (LA) as the template molecule and methacrylic acid (MAA) as the functional monomer. The host–guest complexes formed using LA and MAA were characterized by hydrogen nuclear magnetic resonance and ultraviolet–visible absorption spectroscopy. The obtained results showed that the interaction between LA and MAA mainly relied on hydrogen bonding. The surface morphologies and chemical structures of the MIPs were characterized by scanning electron microscopy. MIPs were spherical in shape with a relatively regular sphericity, rough surface structure, and numerous small holes, which significantly reduced the mass transfer resistance of the template molecules and exhibited excellent recognition performance for template molecules. In addition, soil samples were pretreated with solid-phase extraction columns molecularly imprinted with LA, and analyzed by high-performance liquid chromatography. The recoveries of LA, bromacil, and terbacil were up to 89.65%, 53.17%, and 44.63%, respectively. The developed method showed a minimum detection limit of 10–50 µg·mL−1. In view of the continuous increase of public requirements for pesticide residue detection, a versatile pretreatment method was developed that is green, rapid, simple, and can be miniaturized.

Coumarin-based fluorescent probe synthesized by one-step reaction for sensitive detection of hydrazine and its application

Abstract A coumarin-derivative fluorescent probe 3-(2-naphthyl)-7-acetoxycoumarin (TTAM) for hydrazine detection was successfully designed and synthesized. Hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry showed that the nucleophilic substitution that occurred between hydrazine and the acyl oxide group of TTAM led to the probe fluorescence intensity increasing significantly and a remarkable color change that could be distinguished by using the naked eye. The reaction could be finished in 120 s and the detection limit was only 3.1 × 10−8 M. Moreover, a simple test paper was successfully developed that could be applied for the rapid detection of hydrazine in water samples.

Preparation of the black rice starch-gallic acid complexes by ultrasound treatment: Physicochemical properties, multiscale structure, and in vitro digestibility

This study aimed to investigate the multiscale structure, physicochemical properties, and in vitro digestibility of black rice starch (BRS) and gallic acid (GA) complexes prepared using varying ultrasound powers. The findings revealed that ultrasonic treatment disrupted BRS granules while enhancing the composite degree with GA. The starch granules enlarged and aggregated into complexes with uneven surfaces. Moreover, the crystallinity of the BRS-GA complexes increased to 22.73 % and formed V6-I-type complexes through non-covalent bonds. The increased short-range ordering of the complexes and nuclear magnetic resonance hydrogen (1H NMR) further indicated that the BRS and GA molecules interacted mainly through non-covalent bonds such as hydrogen bonds. Additionally, ultrasound reduced the viscoelasticity of the complexes while minimizing the mass loss of the complexes at the same temperature. In vitro digestion results demonstrated an increase in resistant starch content up to 37.60 % for the BRS-GA complexes. Therefore, ultrasound contributes to the formation of V-typed complexes of BRS and GA, which proves the feasibility of using ultrasound alone for the preparation of starch and polyphenol complexes while providing a basis for the multiscale structure and digestibility of polyphenol and starch complexes.

Preparation of a low-temperature poly (amino acids) demulsifier and its demulsification mechanism

To improve the universality and efficiency of polymer demulsifiers at low temperatures, a unique type of biodegradable poly (ε-carbobenzyloxy-L-lysine) -block-poly (L-phenylalanine) (PZLL-b-PPA) demulsifier with stronger polarity and higher aromaticity was developed. The molecular structure and weight of PZLL-b-PPA were determined using Fourier transform infrared (FT-IR) spectroscopy, 1H nuclear magnetic resonance hydrogen spectra (NMR) and gel permeation chromatography (GPC). A bottle test was used to evaluate the demulsification performance of PZLL-b-PPA with different block ratios, structure and interfacial activity. Numerous critical variables, such as demulsifier structure and dosage, pH levels, emulsion salinity, oil content and oil type, were carefully examined. The demulsification results showed that PZLL5-b-PPA25 has excellent low-temperature demulsification capability and can effectively separate oil from water emulsions with different pH values (4.0 ∼ 11.0) and oil contents ranging from 1.0 ∼ 20.0 wt% within 2 min at room temperature. The best demulsification efficiency reached 99.98 %, with only 6.0 mg/L of residual oil in the separated water. The analysis of interfacial self-assembly behavior revealed that PZLL-b-PPA has a strong affinity for aromatic molecules and exhibits high interfacial activity. The quantum chemical calculation indicated that the main chain polyamide skeleton of PZLL-b-PPA has a stronger interaction for asphaltene, resin and naphthenic acid molecules than conventional oxygen-containing skeleton polymers. Furthermore, the microscopy analysis indicated that PZLL-b-PPA has excellent capacity for flocculation and coalescence of oil droplets in an O/W emulsion. As a result, when PZLL-b-PPA is added to the emulsion, it can quickly migrate to the oil-water interface and interact with and displace the emulsion's stabilizers (asphaltenes and resins), promoting oil droplet coalescence and separation from water at low temperature.

Characterization of a Novel TiF4 Inclusion Complex and in vitro Evaluation of Its Effect on Inhibiting Enamel Demineralization

Introduction: Titanium tetrafluoride (TiF4) is an anticariogenic agent with high remineralizing potential. However, the acidic pH of TiF4 solution can limit its clinical application. The present study aimed to prepare and characterize a new TiF4-dendrimer inclusion complex and evaluate its ability to inhibit enamel demineralization under pH cycling conditions. Methods: PEG-citrate dendrimer and TiF4-dendrimer inclusion complex were synthesized and their molecular structures were evaluated using Fourier-transform Infrared Spectroscopy (FTIR), Hydrogen Nuclear Magnetic Resonance (HNMR), and Liquid Chromatography-Mass Spectrometry (LC-MS) tests. Forty-eight enamel samples were prepared and randomly divided into four groups: distilled water (negative control), TiF4 solution (T), dendrimer solution (D), and TiF4-dendrimer solution (TD). The microhardness of the samples was measured initially. Next, the samples underwent pH cycling, were exposed to the solutions, the microhardness was measured again, and microhardness loss was calculated. EDX analysis was performed on the surface and cross-sectional segments of the samples. Results: The microhardness loss was significantly higher in control (−65.1 ± 6.0) compared to other groups. No significant difference was observed between T (−47.9 ± 5.6) and D (−41.7 ± 12.0) and also D and TD (−40.5 ± 9.4) in this regard. Microhardness loss was significantly higher in T compared to TD group. The TD samples showed similar fluoride and titanium content in both surface and subsurface regions, while the T group had higher concentrations in the surface region. Moreover, the TD solution had a higher pH of 3.4 compared to the T solution’s pH of 1.1. Conclusion: No significant difference was observed between the efficacy of TiF4-dendrimer and TiF4 solution in inhibiting demineralization while TiF4-dendrimer solution had the added advantage of having a higher pH.

Redox-responsive Nanomicelles with Intracellular Targeting and Programmable Drug Release for Targeted Tumor Therapy.

Anti-inflammatory medications, in particular aspirin, have chemopreventive and anticancer adjuvant effects on specific types of cancers, according to ongoing anti-tumor research. Additionally, efforts have been made to transform Poly(salicylic acid) (PSA) into delivery-related nanocarriers. to transport anticancer medications into nanocarriers. However, tumor cell targeting and tumor selectivity were lacking in the salicylic acid polymer-based nanocarriers, preventing them from performing to their full potential. The objective of this study is to prepare targeting and reduction-responsive poly pre-drug nanocarriers (HA-ss-PSA NPs) and to investigate the feasibility of delivering adriamycin (DOX) as nanocarriers. The structures of the polymers were confirmed by nuclear magnetic resonance hydrogen spectroscopy (1H-NMR) and infrared spectroscopy (IR); the encapsulation rate and drug loading of DOX-loaded nanoparticles were determined by HPLC; and the anti-tumor effects of the carriers were evaluated by MTT experiments and in vivo</i> experiments. The prepared nanocarriers had uniform particle size distribution. The drug release rate was up to 80% within 48 h in the tumor environment. DOX/HA-ss-PSA NPs showed significant cytostatic effects. In addition, HA-ss-PSA NPs showed significant targeting and inhibition of cell migration in cell uptake and scratch assays. In vivo</i> experiments showed that the prepared carriers had high tumor inhibition rates, good targeting effects on the liver and tumor, and significantly reduced toxicity to other tissues. The prepared HA-ss-PSA NPs could effectively inhibit the growth of HepG2 cells and tumors in vivo</i>, indicating that PSA could be used as a backbone component of a safe and reliable drug delivery system, providing a new strategy for the treatment of liver cancer.

Synthesis and performance evaluation of a novel zwitterionic quaternary copolymer for enhanced oil‐recovery application

AbstractA novel quaternary copolymer of AA/AM/AOS/C16‐DMAAC was synthesized with acrylic acid (AA), acrylamide (AM), sodium α‐alkenyl‐sulfonate (AOS), and dimethyl‐hexadecyl‐allyl‐ammonium chloride (C16‐DMAAC), using ammonium persulfate and sodium bisulfate (NH4)2S2O8‐NaHSO3) as initiators. The structure of AA/AM/AOS/C16‐DMAAC was characterized using Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. It can be found that the thickening capacity, shearing resistance, temperature‐resistance, salt‐resistance, and emulsification properties of AA/AM/AOS/C16‐DMAAC were superior to those of most widely and cost‐effective partially hydrolyzed polyacrylamide (HPAM) solution at the same concentration. Specifically, the viscosity retention rate of AA/AM/AOS/C16‐DMAAC (3000 mg/L) solution was 86%, which was better than that of HPAM solution (52%) after 30 s of mechanical shearing at 28000 r/min. In addition, the enhanced oil recovery of AA/AM/AOS/C16‐DMAAC solution was 16% at 65 °C, which was about 1.5 times higher than that of HPAM solution (11%). Significantly, successful synthesis of zwitterionic quaternary copolymer emphasizes the importance of a systematic approach to designing appropriate copolymers for enhanced oil recovery.Highlights A novel zwitterionic quaternary copolymer of AA/AM/AOS/C16‐DMAAC was successfully synthesized. The performance on thickening capacity, shearing resistance, temperature‐resistance, salt‐resistance, and emulsification properties of AA/AM/AOS/C16‐DMAAC was superior to that of the most widely used partially hydrolyzed polyacrylamide (HPAM). The enhanced oil recovery of AA/AM/AOS/C16‐DMAAC (16%) was about 1.5 times higher than that of HPAM (11%).

Synthesis and characterization of hydroxamic acid N,3-dihydroxy-2-naphthamide and its copper (II) complex per keto/enol forms and rare earth flotation

Flotation is the most common beneficiation process used for separating minerals, but for rare earth minerals (REMs), performance can suffer due to the dilute nature of the rare earth elements. Furthermore, the REMs tend to possess smaller grain sizes, making the use of traditional flotation cells difficult if total liberation is needed. Consequently, improved efficiencies are needed for extracting REMs from various sources. For these systems, hydroxamic acids are commonly used as flotation collectors. Two such hydroxamic collectors were studied in this work: salicylhydroxamic acid (SHA) and N,3-dihydroxy-2-naphthamide (H2O5). Because there is no documented synthesis route for H2O5, several synthesis approaches were examined. Furthermore, because there is no information on H2O5, important structural and characteristic data was gathered regarding its (1) preferred structural isomer as a Cu2+ complex and (2) electrostatic potential values of the possible dentate groups in different tautomeric forms, thereby allowing H2O5 to be compared to SHA, particularly regarding flotation behavior. Hydrogen nuclear magnetic resonance (H-NMR), Laser Raman Spectroscopy (LRS), and predominantly Fourier-Transform Infrared (FT-IR) spectroscopy showed that both SHA and H2O5 preferred to be keto tautomers when uncomplexed; however, once chelated to Cu2+ ions, the collectors adopted enol forms. Molecular modeling using Spartan software showed an increase in the electrostatic potential of the possible dentate groups in both molecules for the enol form. H2O5 also resulted in an increased recovery by flotation of REMs of about 23% compared to SHA at similar reagent dosages.

Synthesis and Characterization of Polyester Derived from Glycerol and Its Application as an Adhesive on Different Adherents

With the increase in the supply of glycerol and its economic devaluation, it is important to develop strategies that add value to this substance. Among the various alternatives, one application is its use as a precursor in the synthesis of new polyesters. Therefore, this work describes the condensation reaction of glycerol with valeric acid, obtaining functionalized glycerol, which was used in the polycondensation reaction with terephthalic acid. The samples were characterized by infrared spectroscopy, thermogravimetric analysis, hydrogen nuclear magnetic resonance and differential scanning calorimetry. Spectroscopic analyses confirmed the conversion of the reagents into esters and polyesters. The polyesters showed superior thermal stability than the individual components, a glass transition temperature of -3.8 °C and adhesive properties on glass, wood, paper and rigid polyvinyl chloride substrates. The adhesive capabilities of the samples were compared with those of commercial adhesives already established in the Brazilian market. Samples of polyesters synthesized through the reaction between functionalized glycerol and terephthalic acid showed adhesive behavior in the range of mechanical resistance observed in commercial adhesives, with an elastic modulus ranging from 60.9 ± 36.0 MPa to 162.1 ± 102.4 kPa, depending on the type of adhesive substrate, behaving either as an elastic and/or thermoplastic adhesive.

Sex differences in plasma metabolites in a guinea pig model of allergic asthma.

Sex seems to be a contributing factor in the pathogenesis of bronchial asthma. This study aimed to find sex-related differences in metabolome measured by hydrogen-1 nuclear magnetic resonance ((1)H NMR) spectroscopy in healthy and ovalbumin (OVA)-sensitized guinea pigs. Adult male and female animals were divided into controls and OVA-sensitized groups. OVA-sensitization was performed by OVA systemic and inhalational administration within 14 days; on day 15, animals were killed by anesthetic overdose followed by exsanguination. Blood was taken and differential white blood cell count was measured. Left lung was saline-lavaged and differential cell count in the bronchoalveolar lavage fluid (BALF) was measured. After blood centrifugation, plasma was processed for (1)H NMR analysis. Metabolomic data was evaluated by principal component analysis (PCA). Eosinophil counts elevated in the BALF confirming eosinophil-mediated inflammation in OVA-sensitized animals of both sexes. Sex differences for lactate, glucose, and citrate were found in controls, where these parameters were lower in males than in females. In OVA-sensitized males higher glucose and lower pyruvate were found compared to controls. OVA-sensitized females showed lower lactate, glucose, alanine, 3-hydroxy-butyrate, creatine, pyruvate, and succinate concentrations compared to controls. In OVA-sensitized animals, lactate concentration was lower in males. Data from females (healthy and OVA-sensitized) were generally more heterogeneous. Significant sex differences in plasma concentrations of metabolites were found in both healthy and OVA-sensitized animals suggesting that sex may influence the metabolism and may thereby contribute to different clinical picture of asthma in males and females.

Preparation and Characterization of Conductive/Self-Healing Resin Nanocomposites Based on Tetrafunctional Furan-Functionalized Aniline Trimer Modified Graphene.

The nanocomposites with reversible cross-linking covalent bonds were prepared by reacting furfurylamine (FA)-modified diglycidyl ether of bisphenol A (DGEBA) and furfuryl-functionalized aniline trimer-modified graphene (TFAT-G) with bismaleimide (BMI) via the Diels-Alder (DA) reaction. The successful synthesis of the TFAT modifier is confirmed by nuclear magnetic resonance (NMR) hydrogen spectroscopy and IR spectroscopy tests. The structure and properties of TFAT-G epoxy nanocomposites are characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), tensile, and resistivity. The results show that TFAT-G was uniformly dispersed in the resin, and 1 wt% TFAT-G composites increased to 233% for tensile strength, 63% for elongation at break, 66% for modulus, and 7.8 °C for Tg. In addition, the addition of unmodified graphene degrades the mechanical properties of the composite. Overall, the graphene/self-healing resin nanocomposites have both good self-healing function and electrical conductivity by adding 1 wt% modified graphene; this allows for the maintenance of the original 83% strength and 89% electrical conductivity after one cycle of heating repair.

Preparation and displacement performance of ternary copolymer (HAPEC)/graphene oxide composites

How to deal with high temperature and high salt reservoirs is a great challenge in the field of polymers. In this paper, a functional monomer (APEC) was homemade, copolymerized with acrylic acid and acrylamide to form a terpolymer, and solution blended with graphene oxide (GO) to prepare a terpolymer/graphene oxide composite (HAPEC/GO). The optimal ratio HAPEC/GO = 20:1 (GH20) was screened. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), and electron microscopy (SEM). The temperature sensitivity, salt resistance, rheology, and aging resistance of GH20 were found to be superior to hydrolyzed polyacrylamide (HPAM), as evaluated by the apparent viscosity of the solution. When tested under simulated water conditions of 90 °C and 1.0 × 105 mg/L total mineralization, the GH20 solution demonstrated a further improvement in recovery, reaching 16.99 % compared to water flooding alone. The final recovery was 7.49 % higher than that of HPAM. The results demonstrate that the composite prepared can be effectively utilized in reservoirs with high temperature and high salt conditions, making it a promising method for enhanced oil recovery.