Carboxyl Functional Groups Research Articles

Cell Adhesion and Local Cytokine Control on Protein-Functionalized PNIPAM-co-AAc Hydrogel Microcarriers.

Achieving adequate cell densities remains a major challenge in establishing economic biotechnological and biomedical processes. A possible remedy is microcarrier-based cultivation in stirred-tank bioreactors (STBR), which offers a high surface-to-volume ratio, appropriate process control, and scalability. However, despite their potential, commercial microcarriers are currently limited to material systems featuring unnatural mechanical properties and low adaptability. Because matrix stiffness and ligand presentation impact phenotypical attributes, differentiation potential, and genetic stability, biotechnological processes can significantly benefit from microcarrier systems tailorable toward cell-type specific requirements. This study introduces hydrogel particles co-polymerized from poly(N-isopropylacrylamide) (PNIPAM) and acrylic acid (AAc) as a platform technology for cell expansion. The resulting microcarriers exhibit an adjustable extracellular matrix-like softness, an adaptable gel charge, and functional carboxyl groups, allowing electrostatic and covalent coupling of cell adhesive and cell fate-modulating proteins. These features enable the attachment and growth of L929 mouse fibroblast cells in static microtiter plates and dynamic STBR cultivations while also providing vital growth factors, such as interleukin-3, to myeloblast-like 32D cells over 20 days of cultivation. The study explores the effects of different educt compositions on cell-particle interactions and reveals that PNIPAM-co-AAc microcarriers can provide both covalently coupled and diffusively released cytokine to adjacentcells.

Green synthesis of fluorescent N-doped carbon quantum dots from castor seeds and their applications in cell imaging and pH sensing.

Water-soluble fluorescent N-doped carbon quantum dots (N-CQDs) were hydrothermally prepared through a green synthesis route using castor seeds as a single precursor and a hydrothermal method. Several experimental techniques have been used to characterize synthesized N-CQDs to confirm their structure and to verify their applicability in cell imaging and pH sensing. The synthesized N-CQDs were found to have are characterized by amorphous nature with a spherical shape with an average particle size of 6.57nm as revealed from XRD and TEM measurements. The FTIR results reveal the presence of carboxylic and hydroxyl functional groups on the surface of the CQDs, which was also confirmed by XPS analysis. The fluorescence characterization of the synthesized N-CQDs showed blue emission and excitation dependence with good photostability. It was found that the optimal excitation and emission wavelengths were (λEx = 360) and (λEm = 432) nm, respectively. The fluorescence quantum yield (QY) of about 9.6% at the optimum excitation wavelength 360nm. Moreover, the fluorescence intensity of N-CQDs showed good linear dependence with the pH values in ranges of 3.5 - 7.5 and 8 - 12 as well as high sensitivity for slight changes of pH values. According to these results, two fluorescent pH sensors were created based on acidic and basic media. The obtained N-CQDs have zeta potential of -21.86 mV and thus have excellent stability in water. Moreover, N-CQDs derived from the castor seeds have antimicrobial activity and exhibits low cytotoxicity to WI-13 cells with IC50 = 394.4 ± 13.8µg/mL. The results of this study demonstrated that the synthesized N-CQDs derived from castor seeds can be used as pH sensing and antimicrobial materials. On the other hand, they are also promising in applications in cell imaging, thermo-sensing and optoelectronics.

Compatibility and antimicrobial activity of silver nanoparticles synthesized using Lycopersicon esculentum peels.

Nanoparticles have gained worldwide attention as a new alternative to chemical control agents due to their special physiochemical properties. The current study focused on the environmentally friendly synthesis of silver nanoparticles (AgNPs) using Lycopersicon esculentum peel. In addition to studying the intrinsic cytotoxic effectiveness of Le-AgNPs contribute to their antibacterial, and antifungal activities and the effect of nanoparticles on the integrity of their morphological behavior. The initiative biosynthesis of L. esculentum silver nanoparticles (Le-AgNPs) was indicated by the color change of L. esculentum (Le) extract mixed with silver nitrate (AgNO3) solution from faint pink to faint brown. UV-visible spectroscopy, Dynamic light scattering (DLS), Fourier-transform infrared spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction techniques were used to characterize biosynthesized Le-AgNPs. Results of UV-visible spectroscopy recorded surface plasmon resonance at 310nm for SPR of 2.5. The DLS results showed particles of 186nm with a polydispersity index of 0.573. The FTIR spectrum indicated the existence of carboxyl, hydroxyl, phenolic, and amide functional groups. The HR-TEM analysis revealed quasi-spherical crystal particles of Le-AgNPs. Le-AgNPs had a negative zeta potential of - 68.44mV, indicating high stability. Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 8739 were the most susceptible pathogens to Le-AgNPs inhibition, with inhibition zone diameters (IZDs) of 4.0 and 0.92cm, respectively. However, Listeria monocytogenes NC 013768 and Shigella sonnei DSM 5570 were the most resistant pathogens, with IZDs of 0.92 and 0.90cm, respectively. Le-AgNPs demonstrated good inhibitory potential against pathogenic fungi, with IZDs of 3.0 and 0.92cm against Alternaria solani ATCC 62102 and Candida albicans DSM 1386, respectively. The cytotoxicity effect was observed at a half-maximal inhibitory concentration (IC50) of 200.53μg/ml on human colon NCM460D normal cells.

Construction of a Fluorescence/Phase-Change Dual-Mode Sensor Based on Carbon Dots/Poly(acrylic acid) for Highly Selective and Sensitive Detection of Ferric Ions.

Fe3+ is one of the crucial metal ions in biological systems, and its excess or deficiency in the body can trigger various diseases, posing a serious threat to human health. Moreover, improper handling or disposal of Fe3+ can lead to water pollution, thereby harming the environment. Therefore, the development of highly selective and sensitive Fe3+ detection probes is particularly urgent. In this paper, a dual-mode sensor based on sol-gel and fluorescence signal responses was developed for the visual detection of Fe3+. The visual sensing method based on the simultaneous response of Fe3+-triggered dual signals can minimize the interference from false-positive signals and enhance detection accuracy. The dual-mode sensor, denoted as PAA@CDs, was constructed by incorporating high-brightness (high fluorescence emission intensity) green-yellow carbon dots (CDs) into poly(acrylic acid) (PAA), which possesses a large number of carboxyl functional groups. Based on the interaction of Fe3+ with the surface functional groups of CDs, nonfluorescent complexes are formed, leading to nonradiative electron transfer, which induces fluorescence quenching and produces a fluorescence signal visible to the naked eye. Additionally, the interaction of Fe3+ with the carboxyl groups of PAA triggers the cross-linking of PAA, causing a sol-gel phase change signal. Consequently, the PAA@CDs exhibit a dual-response signal in Fe3+ detection. Based on the fluorescence method, the linear detection range of PAA@CDs for Fe3+ is 0.05-2.60 mM with a limit of detection (LOD) of 5.14 μM. Meanwhile, using the sol-gel method, the linear detection range is 0.02-2.20 mM, and the LOD is 42.5 μM. Furthermore, the PAA@CDs probes can be successfully applied to the detection of Fe3+ in real water samples, demonstrating their potential value in the analysis of real samples containing multiple ions.

Conversion of Carboxylic Acids to Sulfonamide Bioisosteres via Energy Transfer Photocatalysis.

More than 450 drugs containing a carboxylic acid functional group have been marketed worldwide. Herein, we report a concise and environmentally friendly organic photoinduced protocol for the interconversion of carboxylic acids into their bioisosteres. With this strategy, a variety of substrates, including alkyl, (hetero)aryl, and alkenyl acids, as well as various biologically relevant acids are successfully converted into primary sulfonamides.

Influence of flame stability on iron oxide nanoparticle growth during FSP

Flame stability during flame spray pyrolysis (FSP) remains an active topic of investigation due to its impact on synthesised particle attributes and purity. The unique feature of the burner investigated here is the ability to control flame stability over newly defined stability maps. The novelty of the current work lies in understanding the influence of these broad stability modes on nanoparticle growth during FSP and on the attributes of collected products. Several distinct flame configurations are selected for iron oxide nanoparticle synthesis, ranging from stable to highly unstable flames. The flame stability regimes are characterised by OH∗ chemiluminescence and broadband flame luminescence imaging. Stability is correlated with the coefficient of variation of flame luminescence (CV) and flame height with mean OH∗ chemiluminescence. Planar Mie scattering is then used to identify the effect of flame luminescence intermittency on spray atomisation and evaporation quality. For particle analysis, in-situ thermophoretic sampling is performed from 30 to 200 mm above the burner exit plane and analysed via transmission electron microscopy (TEM). Further ex-situ analysis is also performed on the bulk-collected product via high-resolution TEM, X-ray powder diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). It is demonstrated that flames with higher instability (CVmin ≥ 0.35) maintain increased spray heights (>26 %) and reduced flame heights (>79 %) compared to stable flames with the same precursor volume flowrate. This reduces the high-temperature particle residence time for primary particle growth and impacts subsequent agglomeration. For example, the mean diameter of gyration and primary particle diameter are found to vary by 44 % and 29 % depending on the flame regime, respectively. Ex-situ analysis also demonstrates that the dominant iron oxide phase produced is maghemite regardless of the stability regime. However, higher concentrations of organic impurities including methyl, methylene and carboxylate functional groups are found via ATR-FTIR with increased flame instability (CV).

An investigation into the performance and perikinetics of Brassica nigra meal in the treatment of real vegetable oil refinery condensate effluent.

In this study, the treatment of vegetable oil refinery plant condensate effluent (VORCE) having high total suspended solids (TSS) and chemical oxygen demand (COD) generated from acid oil unit was focused. The utilization of waste Brassica nigra meal (BNM) as protein flocculant in treating VORCE was explored. The B. nigra meal flocculant (BNMF) exhibited a crystalline nature, with the presence of amino and carboxyl functional groups, rendering it highly efficient (89.69% efficiency) in floc formation. Zeta potential and particle size (-5.6mV and 240.68 nm, respectively) indicate BNMF's effectiveness in initiating floc formation. The interactive effects of pH, dosage, settling time on COD, and TSS removal were investigated using the Box-Behnken design. At an optimal pH of 6.9 and BNMF dosage of 0.77 g/L, a maximum removal of 85.38% COD and 72.56% TSS was obtained. The perikinetic theory for the coagulation-flocculation followed a second-order rate reaction with high Kc (0.0001 L/mg min), low settling time (37.04 min), and high collision efficiency (2.703 × 1017), indicating the model's significance in achieving maximum COD and TSS removal. These findings highlight the potential use of BNMF in the treatment of VORCE, leading to circular economy by valorizing waste from mustard oil extraction and zero discharge. PRACTITIONER POINTS: Valorization of waste Brassica nigra meal (BNM) as a potent protein flocculant Optimization for vegetable oil refinery condensate effluent (VORCE) treatment was done. Interactive effects of the process parameters were analyzed using Design expert. Perikinetic theory for VORCE treatment follows second-order reaction rate with high Kc.

Lipophilic EDTA-based ligands in different diluents for the extraction of rare earths: Preliminary results with Nd(III), Dy(III) and Pr(III) in chloride and nitrate media

A separation method for the recovery of neodymium(III) from two different media, chloride and nitrate, by implementing solvent extraction technique with a novel lipophilic diamide derivative of ethylenediamine tetraacetic acid (EDTA), namely 2,2’-N,N′-didecyl-dioxo-N,N′,N″,N″’-tetraazatetratriacontane-N″,N″’-diyl diacetic acid (H2E4C10), has been investigated. Initial screening results demonstrated acceptable solubility (ca. 15 mM) of the diamide in 1,3-diisopropylbenzene (DiPB) and in a 93:7 v:v n-dodecane:n-octanol mixture (DOm) as non-polar diluents. Further investigations aiming at determining operational parameters associated with the befitted extractant systems were conducted at pH ranging from 2 to 4 in chloride and nitrate media. A pH-dependent performance of the proposed systems revealed loading capacity peaking at pH = 3 with the respective values of 1.7 and 2.0 g L−1 in nitrate and chloride media. The extraction efficiency, the distribution coefficients, and the separation factor (E%,D and SF, respectively) were determined for an equimolar mixture of neodymium and two other potential competitive lanthanides, namely dysprosium and praseodymium. The best selectivity was observed in the chloride medium at pH = 4 yielding SFNd/Pr = 1.48 and SFNd/Dy = 2.03. Neodymium-to-extractant stoichiometry was evidenced in chloroform to be 1:1 H2E:Nd at pH = 2. Thermodynamic constants related to the considered extraction equilibrium have been determined by using the Van't Hoff relation and the slope analysis method. It appeared within the selected pH-range that the mechanism of the Nd3+ transfer was strongly influenced by the nature of the diluent. This was illustrated by the enthalpy-driven transfer when Nd3+ was extracted with the H2E-4C10-Dom system (aliphatic diluent) while the transfer became entropy-driven when the extraction was performed with the H2E-4C10-DiPB system (aromatic diluent). The complexation of Nd3+ involved mainly the participation of both the amide and carboxylic functional groups. The transfer of the cation to the organic phase might occur through the formation of the Nd(HE)A2 complex (where A is either a nitrate or a chloride anion), allowing for the lowest associated standard Gibbs free energy of transfer (−28 < ΔG° < −24 kJ mol−1) regardless of the aqueous feed.

Tannic Acid Carbon Dots with Both Antimicrobial Activity and Selectivity for Fe3+ Detection

AbstractIn the field of antimicrobial nanomaterials, biomass‐derived carbon quantum dots have attracted great attention from contemporary researchers due to their unique physicochemical properties and favorable biosafety. In this study, novel carbon quantum dots (CQDs) were synthesized from tannic acid by a one‐step hydrothermal method. The polymeric CQDs have good surface functionality and hydrophilicity with a large number of hydroxyl, carboxyl and amino functional groups. Antimicrobial experiments showed that CQDs had a good inhibitory effect on Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, as well as the drug‐resistant bacterium methicillin‐resistant Staphylococcus aureus. Scanning electron microscopy showed that the morphology of S.aureus cells treated with CQDs became shrivelled and irregular, the surface of E.coli cells protruded to form irregular vesicles, and the whole became shriveled up, whereas MRSA cells appeared to be depressed in the middle, and there was a residue of adherent CQDs on the cell surface. In addition, CQDs exhibit selective fluorescence bursting behavior for ferric ions and can be used as fluorescent probes for rapid, sensitive and selective detection of Fe3+. Therefore, CQDs not only possess good bacteriostatic properties, but also serve as fluorescent sensors for the detection of Fe3+. It can be used as a potential sensing array for selective detection of iron ions and bacterial abatement from contaminated water.

High-effective, convenient and environmental-friendly MOFs-chitosan-glyoxal composite film for ceftizoxime adsorption: Behavior and mechanisms.

In this work, a novel PCN-222-chitosan-glyoxal (PCN@CSG2) composite film was constructed by loading PCN-222 in chitosan substrate, and used for ceftizoxime adsorption. The results demonstrated that the PCN@CSG not only had excellent adsorption properties for ceftizoxime, but also maintained excellent structural properties in harsh environments (strong acids and alkalis), making it have good recycling performance. Specifically, the adsorption kinetics and isotherms investigation demonstrated that the adsorption process followed the pseudo-second-order kinetic model and Freundlich isotherm model respectively, indicating that it was a multilayer process mainly controlled by chemisorption. The PCN@CSG possesses excellent absorptive capacity of 561.7 mg·g-1 and reaches equilibrium rapidly within 60 min, which is attributed to the structural advantages of PCN-222 and chitosan. The amino, carboxyl and hydroxyl functional groups of PCN-222 provide numbers of active sites and cationic chitin greatly promoted the electrostatic adsorption with negative ceftizoxime. In addition, the PCN@CSG has the advantages of renewable and environment-friendly for the biodegradation of chitosan. After five consecutive adsorption-desorption cycles, the removal rate was still higher than 90 %, confirming the excellent reusability of PCN@CSG. This work provided a great prospect for the design and application of shaped-MOFs composite materials for the removal of cephalosporins in environmental water.

Fabrication of Anatomically Equivalent Pectin-Based Multifilament Nerve Conduits.

Reuniting denuded nerve ends after a long segmental peripheral nerve defect is challenging due to delayed axonal regeneration and incomplete, nonspecific reinnervation, as conventional hollow nerve guides fail to ensure proper fascicular complementation and obstruct axonal guidance across the defects. This study focuses on fabricating multifilament conduits using a plant-derived anionic polysaccharide, pectin, where the abundant availability of carboxylate (COO-) functional groups in pectin facilitates instantaneous sol-gel transition upon interaction with divalent cations. Despite their advantages, pectin hydrogels encounter structural instability under physiological conditions. Hence, pectin is conjugated with light-sensitive methacrylate residues (49.8% methacrylation) to overcome these issues, enabling the fabrication of dual cross-linked multifilament nerve conduits through an ionic interaction-driven, template-free 3D wet writing process, followed by photo-cross-linking at 525 nm. The anatomical equivalence including peri-, epi-, and endoneurium structures of the customized multifilament conduits was confirmed through scanning electron micrographs and micro-CT analysis of rat and goat sciatic nerve tissues. Furthermore, the fabricated multifilament nerve conduits demonstrated cytocompatibility and promoted the expression of neuron-specific intermediate filament protein (NF-200) in PC12 cells and neurite outgrowth of 16.90 ± 1.82 μm on day 14. Micro-CT imaging of an anastomosed native goat sciatic nerve with an 8-filament conduit demonstrated precise fascicular complementation in an ex vivo interpositional goat model. This approach not only eliminates the need for a suture-intensive ligation process but also highlights the customizability of multifilament conduits to meet patient- and injury-specific needs.

Influence of Carboxymethyl Chitosan and Sodium Humate Composite Corrosion Inhibitor on the Corrosion Resistance of EH40 Steel in Seawater.

In this study, corrosion weight loss experiments were conducted to explore the corrosion-inhibiting properties of a composite inhibitor consisting of carboxymethyl chitosan (CMCS) and sodium humate (SH) at varying concentrations on EH40 steel in seawater. An investigation was conducted into the electrochemical behavior of EH40 steel in seawater and the mechanism of composite inhibitor consisting of carboxymethyl chitosan (CMCS) and sodium humate (SH) at varying concentrations on EH40 steel in seawater through an electrochemical test. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy and energy-dispersion spectroscopy (SEM-EDS), Fourier transform infrared absorption spectroscopy (FTIR), and contact angle measurements were performed to confirm the mechanism of CMCS and SH as well as their composite corrosion inhibitors at the interface between seawater and EH40 steel. Furthermore, density functional theory (DFT) calculation supports the experimental findings. The results show that CMCS, SH, and their composite inhibitor are a mixed type of corrosion inhibitor that mainly inhibits cathodic reactions and corrosion through the active site blocking mechanisms. Their corrosion inhibition effect increases with the increase of mass concentration, and the composite inhibitor performs better in corrosion inhibition and scale inhibition than the individual inhibitor. When the CMCS mass concentration reaches 100 mg/L and the SH mass concentration reaches 50 mg/L, the corrosion inhibition rate is 74.65%, the corrosion potential shifts by about 47.39 mV, the Rp value increases from 358.6 to 1102.4 Ω·cm2, and the Ydl value decreases from 177.31 Sn Ω-1cm-2 × 10-6 to 92.672 Sn Ω-1cm-2 × 10-6. CMCS and SH are adsorbed onto the surface of EH40 steel, forming a protective film through the complexation of carboxyl, amino, and other functional groups to inhibit corrosion and prevent the further formation of scale. In addition, synergistic coadsorption occurs between CMCS and SH, and the composite corrosion inhibitor exerts a better effect than the individual corrosion inhibitor.

Al(SO4)(OH)·5H2O Stemming from Complexation of Aluminum Sulfate with Water-Soluble Ternary Copolymer and further Stabilized by Silica Gel as Effective Admixtures for Enhanced Mortar Cementing.

A water-soluble ternary copolymer bearing carboxyl, sulfonic, and amide functional groups was synthesized using ammonium persulfate-catalyzed free radical polymerization in water, resulting in high monomer conversion. This copolymer was then complexed with aluminum sulfate, forming an admixture containing Al(SO4)(OH)·5H2O, which was subsequently combined with silica gel. Characterization revealed that the synthesized copolymer formed a large, thin membrane that covered both the aluminum compounds and the silica gel blocks. The introduction of this complex admixture, combining the copolymer and aluminum sulfate, not only reduced the setting times of the cement paste but also enhanced the mechanical strengths of the mortar compared to using aluminum sulfate alone. The complex admixture led to the formation of katoite, metajennite, and C3A (tricalcium aluminate) in the mortar, demonstrating significant linking effects, whereas pure aluminum sulfate could not completely transform C3S within 24 h. Further addition of silica gel to the complex admixture further shortened the setting times of the paste, slightly reduced compressive strength, but improved flexural strength compared to the initial complex admixture. The silicon components appeared to fill the micropores and mesopores of the mortar, accelerating cement setting and enhancing flexural strength, while slightly decreasing compressive strength. This study contributed to the development of new cementing accelerators with improved hardening properties.

Multi-Functional Silole Hole Transport Layer for Efficient and Stable Lead-Tin Perovskite and Tandem Solar Cells.

Despite high theoretical efficiencies and rapid improvements in performance, high-efficiency ≈1.2eV mixed Sn-Pb perovskite solar cells (PSCs) generally rely on poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT: PSS) as the hole transport layer (HTL); a material that is considered to be a bottleneck for long-term stability due to its acidity and hygroscopic nature. Seeking to replace PEDOT: PSS with an alternative HTL with improved atmospheric and thermal stability, herein, a silole derivative (Silole-COOH) tuned with optimal electronic properties and efficient carrier transport by incorporating a carboxyl functional group is designed, which results in an optimal band alignment for hole extraction from Sn-Pb perovskites and robust air and thermal stability. Thin films composed of the Silole-COOH exhibit superior conductivity and carrier mobility compared to PEDOT: PSS, in addition to reduced nonradiative quasi-Fermi-level splitting losses at the HTL/perovskite interface and improved quality of Sn-Pb perovskite. Replacement of PEDOT: PSS with Silole-COOH leads to 23.2%-efficient single-junction Sn-Pb PSCs, 25.8%-efficient all-perovskite tandems, and long operating stability in ambient air.

Comprehensive Investigation into the Impact of Degradation of Recycled Polyethylene and Recycled Polypropylene on the Thermo-Mechanical Characteristics and Thermal Stability of Blends.

The impact of degradation on plastics is a critical factor influencing their properties and behavior, particularly evident in polyethylene (PE) and polypropylene (PP) and their blends. However, the effect of photoaging and thermal degradation, specifically within recycled polyethylene (rPE) and recycled polypropylene (rPP), on the thermo-mechanical and thermostability aspects of these blends remains unexplored. To address this gap, a range of materials, including virgin polyethylene (vPE), recycled polyethylene (rPE), virgin polypropylene (vPP), recycled polypropylene (rPP), and their blends with different ratios, were comprehensively investigated. Through a systematic assessment encompassing variables such as melting flow index (MFI), functional groups, mechanical traits, crystallization behavior, microscopic morphology, and thermostability, it was found that thermo-oxidative degradation generated hydroxyl and carboxyl functional groups in rPE and rPP. Optimal mechanical properties were achieved with a 6:4 mass ratio of rPE to rPP, as validated by FTIR spectroscopy and microscopic morphology. By establishing the chemical model, the changes in the system with an rPE-rPP ratio of 6:4 and 8:2 were monitored by the molecular simulation method. When the rPE-rPP ratio was 6:4, the system's energy was lower, and the number of hydrogen bonds was higher, which also confirmed the above experimental results. Differential scanning calorimetry revealed an increased crystallization temperature in rPE, a reduced crystallization peak area in rPP, and a diminished crystallization capacity in rPE/rPP blends, with rPP exerting a pronounced influence. This study plays a pivotal role in enhancing recycling efficiency and reducing production costs for waste plastics, especially rPE and rPP-the primary components of plastic waste. By uncovering insights into the degradation effects and material behaviors, our research offers practical pathways for more sustainable waste management. This approach facilitates the optimal utilization of the respective performance characteristics of rPE and rPP, enabling the development of highly cost-effective rPE/rPP blend materials and promoting the efficient reuse of waste materials.

Preparation and performance characterization of waterborne epoxy resin modified asphalt emulsion for tack coat

In order to eliminate the possible drawbacks of waterborne epoxy resin (WER) generated by the phase inversion method and the chemical modification method, this study prepared WER using a novel method, i.e., epoxy resin was introduced into the molecular structure of aqueous acrylic resin; after the combination of epoxy resin and the aqueous dispersion process, the aqueous epoxy acrylic resin can be prepared. Waterborne epoxy resin modified emulsified asphalt (WEREA) was then prepared for the application of a tack coat material. Fourier Transform Infrared Spectroscopy (FTIR) test was conducted to explore the possible reactions between the compositions. A rheology test, direct tension test, pull-off bonding test, and oblique shear test were also conducted. Results indicated that in the FTIR test, a new peak around 1732 cm−1 was formed due to the reaction between the carboxyl functional group in WER and the amino group in curing agent to form an ester bond. The incorporation of WER led to an elevation in the complex modulus and a simultaneous reduction in the phase angle of WEREA. When the temperature was larger than 60 °C, the phase angle showed a decreased trend, indicating the material became less viscous due to the increased temperature, illustrating thermosetting characteristics of epoxy resin. As the content of waterborne epoxy resin (WER) increased, there was an observed decrease in the direct tensile rate, coupled with a concurrent increase in direct tensile strength. When the ratio of emulsified asphalt and WER was 1:0.6, the tensile strength of WEREA increased by 811% in contrast to the specimen without the inclusion of WER. There existed different optimal WER contents for the pull-off strength tests conducted on different substrates. For asphalt concrete substrate and steel slab substrate, the optimum ratio of emulsified asphalt to WER + curing agent was 1:0.4, and 1:0.8 was the optimum ratio for the cement concrete substrate. When the ratio between emulsified asphalt and the combination of WER along with the curing agent was 1:0.4 (WEREA-4), the oblique shear strength obtained the maximum value, which was increased by 18.7% in contrast to WEREA-0.

Effects of Ageing on Surface Properties of Biochar and Bioavailability of Heavy Metals in Soil

This study aims to explore the effects of biochar ageing on its surface properties and the bioavailability of heavy metals in soil. The biochar was subjected to chemical oxidation/dry–wet cycles (CDWs), chemical oxidation/freeze–thaw cycles (CFTs), and natural ageing (NT) to analyze changes in the elemental composition, pH, specific surface area, pore volume, and surface functional groups. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were applied to characterize the functional groups and microstructure, and the BCR sequential extraction method was employed to demonstrate the fractionation distribution of Cu, Cd, and Pb. The results showed that the CDWs and CFTs treatments significantly reduced the carbon content of the biochar (with a maximum reduction to 47.70%), increased the oxygen content (up to 49.17%), and notably increased the specific surface area and pore volume. The pH decreased significantly from 9.91 to 4.92 and 4.99 for the CDWs and the CFTs, respectively. The FTIR analysis indicated notable changes in hydroxyl and carboxyl functional groups, and the SEM revealed severe microstructural damage in biochar after the CDWs and CFTs treatments. The heavy metal fractionation analysis indicated that exchangeable Cu, Cd, and Pb significantly increased after the CDWs treatment, reaching 31.40%, 5.25%, and 6.79%, respectively. In conclusion, biochar ageing significantly affects its physicochemical properties and increases the bioavailability of heavy metals, raising concerns about its long-term remediation effectiveness.

Crystal structure of perfluorononanoic acid, C9HF17O2

The crystal structure of perfluorononanoic acid (PFNA) was solved via parallel tempering using synchrotron powder diffraction data obtained from the Brockhouse X-ray Diffraction and Scattering (BXDS) Wiggler Lower Energy (WLE) beamline at the Canadian Light Source. PFNA crystallizes in monoclinic space group P21/c (#14) with lattice parameters a = 26.172(1) Å, b = 5.6345(2) Å, c = 10.9501(4) Å, and β = 98.752(2)°. The crystal structure is composed of dimers, with pairs of PFNA molecules connected by hydrogen bonds via the carboxylic acid functional groups. The Rietveld-refined structure was compared to a density functional theory-optimized structure, and the root-mean-square Cartesian difference was larger than normally observed for correct powder structures. The powder data likely exhibited evidence of disorder which was not successfully modeled.

Structural and biological studies on beta – alanine substituted Sulfonamide derivatives: A new class of Juvenile hormone mimics as insect growth regulators

A series of naphthyl-sulfonamide juvenile hormone analogs has been synthesized through one-pot synthesis route using thionyl chloride as an activating agent for carboxylic functional group. The structures of synthesized compounds with general formula C10H7-SO2NH-(CH2)2CON-R1R2 have been confirmed by FT-IR, 1HNMR , 13CNMR , and ESI-MS techniques. The insect growth regulating property of all the synthesized compounds as juvenile hormone analogs (JHAs) has been studied against yellow fever mosquito, Aedes aegypti and tobacco cutworm, Spodoptera litura. The bioassay results demonstrate that the synthesized compounds exhibit insect growth regulating activity in comparison to standard JHAs. The IE50 and IE90 values of B4 are 0.08 and 6.62 ppm, respectively for inhibition of Aedes aegypti and the LC50 and LC90 values of B3 are 11.03 and 45.36 ppm, respectively for Spodoptera litura. Notably, the compounds B3 and B4 showed enhanced efficacy at lower concentrations. Additionally, density functional theory (DFT) technique is used to predict the chemical reactivity and toxicity of the synthesized JHAs in comparison to pyriproxyfen. Further, the DNA-binding study of synthesized JHAs has been carried out using UV–vis spectroscopy for toxicity assessment against DNA and the binding constant values in the range 102 – 103 suggest lower toxicity of all the synthesized molecules in comparison to PYR. All the synthesized JHAs show IGR action and exhibit better reactivity and reduced toxicity as compared to the commercial in use IGRs.

Prediction and investigation of water repeated absorption and release properties of superabsorbent polymers during the dry-wet cycles in different solutions

Superabsorbent polymers (SAP) with a three-dimensional cross-linked network structure are used in the concrete field due to their good water absorption and water retention properties. The changes of its repeated water absorption and release properties have an important impact on crack healing, but there is still a lack of relevant research. This study mainly uses the tea-bag method to explore the repeated water absorption and release behavior of sodium polyacrylate and polyacrylic acid-acrylamide copolymers in deionized water, cement filtrate, and saturated calcium hydroxide solution. The quantitative analysis of the change in the peak area of the water-absorbing functional group was performed by fourier transform infrared spectroscopy. The morphology and elements of SAP under different dry-wet cycles were analyzed by scanning electron microscope-energy spectrum analysis. The repeated swelling behavior of SAP was predicted using the classical models. The results showed that the repeated water absorption performance of SAP gradually decreased with the increase of the number of wet-dry cycles. The slope of the curve for the second-order equation gradually increases, and the peak area corresponding to the carboxyl functional group also gradually increases. And the rate and amount of water release gradually increase. For sodium polyacrylate, with the increase in the number of wet-dry- cycles, the increase in the content of calcium, magnesium, and aluminum elements is accompanied by a significant decrease in the content of sodium elements. In contrast, the calcium content on the surface of polyacrylic acid-acrylamide copolymer increased, but the sodium content only slightly decreased.