Active Functional Groups Research Articles

Investigation on the Tea Polyphenol/Swelling Gels to Inhibit Coal Spontaneous Combustion: An Experimental Study

ABSTRACT Developing new fire-fighting material is most significant for effective prevention and control of coal spontaneous combustion. To enhance the flame-retardant performance of the gel, the tea polyphenol/swelling gels are developed using a water-soluble polymerization method. Thermogravimetric analysis, programmed temperature experiments, and Fourier-transform infrared spectroscopy are used to reveal the structural characteristics, microscopic morphology, and thermal stability of the gel. Experimental testing the tea polyphenol/swelling gels’ water absorption, water retention, and reusability as well as their inhibitory effect on coal spontaneous combustion. The results showed that the prepared tea polyphenol/swelling gels exhibited a porous three-dimensional network structure, with a maximum swelling ratio of 607.2 g/g and a salt absorption rate of 121.4 g/g. After the testing coal sample is treating by the tea polyphenol/swelling gels, its CO production rate is sharply decreased, but the corresponding ignition point temperature and flame-retardant rate are significantly increased. The activation energy in the first stage is increased by 32.2 kJ·mol−1, in the second stage by 4.0 kJ·mol−1, and in the third stage by 23.2 kJ·mol−1. Additionally, the active functional groups such as hydroxyl and methyl in the coal are also reduced by the treatment of tea polyphenol/swelling gels. Correlation analysis indicate that the inhibition effect of coal spontaneous combustion can be achieved by reducing -OH, CH3/CH2 groups, while the increasing of C = C, C- O, C- H functional groups in the coal. Moreover, the tea polyphenol/swelling gels performing the characteristics of excellent water absorption, inhibiting coal spontaneous combustion by absorbing heat, covering the coal microstructure, and inhibiting the oxidative activity of coal molecules. This study can provide theoretical guidance for the application of swelling gels in inhibiting coal spontaneous combustion.

Electrochemical oxidation of seawater using vanadium facilitated quaternary layered double hydroxides integrated with sulfur-doped carbon dots

This research introduces a novel approach to electrocatalysis for sustainable energy generation, revealing the MnCoCrV LDH@SCDs composite supported by nickel foam (NF) as a high-performance catalyst specifically designed for seawater electrolysis. Constructed by incorporating sulfur-doped carbon dots (SCDs) into MnCoCrV layered double hydroxide (LDH) and depositing them onto a nickel foam substrate, this electrocatalyst demonstrates exceptional efficiency in the oxygen evolution reaction (OER) under alkaline seawater conditions. MnCoCrV LDH@SCDs/NF attains a noteworthy current density of 10 mA/cm² with a minimal overpotential of 209.4 mV. Additionally, it demonstrates a reduced Tafel value of 81.5 mV/dec, indicating faster kinetics. The electrode maintains impressive long-term stability, sustaining efficiency for approximately 50 h at a constant current density of 10 mA/cm². The increased surface area and reduced charge transfer resistance contribute to substantial electrocatalytic performance in seawater. This performance is primarily attributed to improved conductivity, resulting from synergistic contributions from high-valence-state vanadium ions and electrochemically active functional groups in SCDs. The MnCoCrV LDH@SCDs/NF electrocatalyst stands out for its intricate features that not only promote efficient electron transfer but also effectively counteract interference from chloride anions in seawater electrolysis. This study underscores the innovative nature of MnCoCrV LDH@SCDs/NF as a pivotal development in electrocatalyst research, offering a promising avenue for harnessing renewable energy from seawater.

Crystallographic structure, antibacterial effect, and catalytic activities of fig extract mediated silver nanoparticles

Silver nanoparticles (Ag NPs) play a pivotal role in the current research landscape due to their extensive applications in engineering, biotechnology, and industry. The aim is to use fig (Ficus hispida Linn. f.) extract (FE) for eco-friendly Ag NPs synthesis, followed by detailed characterization, antibacterial testing, and investigation of bioelectricity generation. This study focuses on the crystallographic features and nanostructures of Ag NPs synthesized from FE. Locally sourced fig was boiled in deionized water, cooled, and doubly filtered. A color change in 45 mL 0.005 M AgNO3 and 5 mL FE after 40 min confirmed the bio-reduction of silver ions to Ag NPs. Acting as a reducing and capping agent, the fig extract ensures a green and sustainable process. Various analyses, including UV–vis absorption spectrophotometry (UV), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDX) and Transmission electron microscopy (TEM) were employed to characterize the synthesized nanoparticles, and Gas chromatography-mass spectrometry (GC-MS) analysis of the fig extract revealed the presence of eleven chemicals. Notably, the Ag NPs exhibited a surface plasmon resonance (SPR) band at 418 nm, confirmed by UV analysis, while FTIR and XRD results highlighted the presence of active functional groups in FE and the crystalline nature of Ag NPs respectively. With an average particle size of 44.57 nm determined by FESEM and a crystalline size of 35.87 nm determined by XRD, the nanoparticles showed strong antibacterial activities against Staphylococcus epidermidis and Escherichia coli. Most importantly, fig fruit extract has been used as the bio-electrolyte solution to generate electricity for the first time in this report. The findings of this report can be the headway of nano-biotechnology in medicinal and device applications.

A novel high reactive initiator system of vinyl‐substituted hydridopolycarbosilane (VHPCS) for lower curing temperature and higher ceramic yields

AbstractVinyl‐substituted hydridopolycarbosilane (VHPCS) is widely studied for its low viscosity, abundance of active functional groups, rapid curing, and high ceramic yield. The curing reactions mainly involve the free radical polymerization of vinyl and hydrosilylation reactions, but these reactions typically require high temperatures such as 160–250°C. The curing behavior of VHPCS‐17 with a tert‐butyl peroxybenzoate/Nickel acetylacetonate (TBPB/NIAA) system is investigated using differential scanning calorimetry and in situ Fourier transform infrared. The properties of VHPCS‐17 with different initiator systems and VHPCS with different vinyl contents (under TBPB/NIAA system) are studied using thermogravimetric analysis and x‐ray diffraction. The results demonstrate that the TBPB/NIAA system can facilitate the free radical polymerization of vinyl; moreover, this system decreases the peak temperature of the curing reaction from 251 to 141°C and increases the ceramic yield from 80.49% to 89.88%. The ceramic yield of cured VHPCS increases gradually, reaching 89.88% when the vinyl content is 17%. The grain size of β‐SiC decreases continuously with the increase in vinyl content, while the high‐temperature oxidation‐resistant properties of SiC ceramics obtained from different VHPCSs are not negatively affected.

Phytofabrication of biocompatible zinc oxide nanoparticle using Gymnema sylvestre and its potent in vitro antibacterial, antibiofilm, and cytotoxicity against human breast cancer cells (MDA-MB-231).

The increasing incidence of breast cancer and bacterial biofilm in medical devices significantly heightens global mortality and morbidity, challenging synthetic drugs. Consequently, greener-synthesized nanomaterials have emerged as a versatile alternative for various biomedical applications, offering new therapeutic avenues. This study explores the synthesis of biocompatible zinc oxide (ZnONPs) nanoparticles using Gymnema sylvestre and its antibacterial, antibiofilm, and cytotoxic properties. Characterization of ZnONPs inferred that UV-Vis spectra exhibited a sharp peak at 370nm. Fourier transform infrared spectroscopical analysis revealed the presence of active functional groups such as aldehyde, alkyne, cyclic alkene, sulfate, alkyl aryl ether, and Zn-O bonds. X-ray diffraction analysis results confirmed the crystalline nature of the nanoparticle. Scanning electron microscope analysis evidenced hexagonal morphology, and energy-dispersive X-ray analysis confirmed zinc content. High-resolution transmission electron microscope analysis showed hexagonal and rod-shaped ZnONPs with a size of 5nm. Zeta potential results affirmed the stability of nanoparticles. The ZnONPs effectively inhibited gram-positive (18-20mm) than gram-negative (12-18mm) bacterial pathogens with lower bacteriostatic and higher bactericidal values. Biofilm inhibitory property inferred ZnONPs were more effective against gram-positive (38-94%) than gram-negative bacteria (27-86%). The concentration of ZnONPs to exert 50% biofilm-inhibitory is lower against gram-positive bacteria (179.26-203.95μg/mL) than gram-negative bacteria (201.46-236.19μg/mL). Microscopic visualization inferred that at 250μg/mL, ZnONPs strongly disrupted biofilm formation, as evidenced by decreased biofilm density and altered architecture. The cytotoxicity of ZnONPs against breast cancer cells showed a dose-dependent reduction in cell viability with an IC50 value of 19.4µg/mL. AO/EB staining indicated early and late apoptotic cell death of breast cancer cells under fluorescence microscopy. The results of hemolytic activity validated the biocompatibility of the ZnONPs. Thus, the unique properties of the green-synthesized ZnONPs suggest their potential as effective drug carriers for targeted delivery in cancer therapy and the treatment of biofilm-related infections.

An Integrative Chemical Recycling Approach for Catalytic Oxidation of Epoxy Resin and in situ Separation of Degraded Products.

Although many approaches have been proposed to recycling waste epoxy resin (EP), the separation of mixed degraded products remains a challenge due to their similar structures. To address this, we present a catalytic oxidation strategy that enables mild degradation of EP and in situ separation of degraded products through supramolecular interactions. The oxidative degradation relies on FeIV=O radicals with strong oxidizing properties, which are generated from the electron transfer of FeCl2 with reaction reagents. As the FeIV=O radicals attacked the C-N bonds of EP, EP was broken into fragments rich in active functional groups. Meanwhile, the FeIV=O radicals were reduced to iron ions that can coordinate with the carboxyl groups on the fragments. As a result, the degraded products with different carboxyl content can be effortlessly separated into liquid and solid phase by coordinating with the catalyst. The success of this work lays the foundation for high-value application of degraded products and provides new design ideas for recycling waste plastics with complex compositions.

An Integrative Chemical Recycling Approach for Catalytic Oxidation of Epoxy Resin and in situ Separation of Degraded Products

AbstractAlthough many approaches have been proposed to recycling waste epoxy resin (EP), the separation of mixed degraded products remains a challenge due to their similar structures. To address this, we present a catalytic oxidation strategy that enables mild degradation of EP and in situ separation of degraded products through supramolecular interactions. The oxidative degradation relies on FeIV=O radicals with strong oxidizing properties, which are generated from the electron transfer of FeCl2 with reaction reagents. As the FeIV=O radicals attacked the C−N bonds of EP, EP was broken into fragments rich in active functional groups. Meanwhile, the FeIV=O radicals were reduced to iron ions that can coordinate with the carboxyl groups on the fragments. As a result, the degraded products with different carboxyl content can be effortlessly separated into liquid and solid phase by coordinating with the catalyst. The success of this work lays the foundation for high‐value application of degraded products and provides new design ideas for recycling waste plastics with complex compositions.

Revealing mechanism of phenol-amine reaction to form humus in compost based on high-resolution liquid chromatography mass spectrometry and spectroscopy

Humus is the stable form of carbon storage in straw compost. The phenol-amine reaction is a pathway for humus formation in straw compost. In this study, two reaction systems, GP group (pyrogallol and glycine) and GCP group (catechol, pyrogallol, and glycine), were constructed in a simulated composting environment and revealed the molecular binding mechanism of the phenol-amine reaction through spectroscopy and mass spectrometry. The results showed that phenolic self-polymerization was faster than phenol-amine reaction. Therefore, the aromatization degree of GP was 27.14 % higher than that of GCP. The phenol-amine reaction first produced fulvic acid, and then formed humus units rich in active functional group structures (i.e., phenolic hydroxyl and carboxyl groups). These units further captured small molecule compounds to form humic acid eventually. This study would provide theoretical support for exploring the humus formation process and the promotion of straw humification by adding phenol or amino acids to compost.

Mesoporous silica nanoparticles as a drug delivery mechanism.

Research in intelligent drug delivery systems within the field of biomedicine promises to enhance drug efficacy at disease sites and reduce associated side effects. Mesoporous silica nanoparticles (MSNs), characterized by their large specific surface area, appropriate pore size, and excellent biocompatibility, have garnered significant attention as one of the most effective carriers for drug delivery. The hydroxyl groups on their surface are active functional groups, facilitating easy functionalization. The installation of controllable molecular machines on the surface of mesoporous silica to construct nanovalves represents a crucial advancement in developing intelligent drug delivery systems (DDSs) and addressing the issue of premature drug release. In this review, we compile several notable and illustrative examples of MSNs and discuss their varied applications in DDSs. These applications span regulated and progressive drug release mechanisms. MSNs hold the potential to enhance drug solubility, improve drug stability, and mitigate drug toxicity, attributable to their ease of functionalization. Furthermore, intelligent hybrid nanomaterials are being developed, featuring programmable properties that react to a broad spectrum of stimuli, including light, pH, enzymes, and redox triggers, through the use of molecular and supramolecular switches.

Preparation of dopamine/L-cysteine modified PVDF composite membrane and its application in the removal of mercury ions from water

Polyvinylidene fluoride (PVDF), embodying a stabilization under thermal environment and capability to resist chemical corrosion, is widely used as a membrane-forming material. However, its inherent hydrophobicity and lack of active functional groups in the structure limit its suitability for adsorption applications. In this study, PVDF-based membranes were first prepared by the non-solvent phase inversion method, and then, polydopamine (PDA) was coated on these membranes by the oxidative self-polymerization of dopamine (DA). Then, L-cysteine (LCys) was grafted by self-assembly to obtain a highly hydrophilic PVDF composite (PVDF@PDA-LCys) membrane with excellent ability for Hg(II) ion capture. The membrane has the following characteristics: excellent hydrophilicity, with a water contact angle (WCA) that drops to 0° within 3 s, which is far superior to the 89.22° WCA of the PVDF-based membrane. Given an 10 mg·L−1 initial concentration of Hg(II), adsorption experiences 120 min, the removal efficiency reaches 95.14%. The fitted maximum adsorption capacity is 97.98 mg·g−1. Additionally, the composite membrane exhibits good acid resistance. When the solution pH is as low as 1.5, the Hg(II) ion removal efficiency is still close to 70%. The performance of the composite membrane remains stable after repeated use. This study demonstrates an environmentally friendly and practical method for preparing PVDF-based composite membranes with potential applications in wastewater treatment.

Ammonia vapour detection at room temperature via carbon quantum dots based facile system

With widespread industrial use of ammonia and its potential hazards to both human health and the environment, ensuring reliable detection has become paramount. In the present work, we report a study on a novel and highly sensitive gas sensing material, composed of carbon quantum dots (CQDs) for the detection of ammonia vapor at room temperature. The CQDs were synthesized at 200 °C using a hydrothermal single-step process. To investigate the morphology and chemical composition, CQDs were characterized by Fourier transform infrared spectroscopy, Transmission Electron Microscopy, photoluminescence, and UV–Vis spectroscopy. A thin-film of CQDs was then deposited on an ITO-coated glass substrate for the detection and quantification of ammonia vapor (NH3) by monitoring the response under ambient conditions. By corresponding change in conductance, the change in resistance of the film is investigated. The enhanced properties of sensing of the ammonia samples may be due to the combined effect of localized electronic surface states of CQDs and chemical sensitization caused by the catalytic properties of an active functional group on the CQDs surface. Notably, this sensor exhibits higher sensitivity, excellent response time, and greater stability to ammonia vapours compared to previous reports.

Experimental study on the mechanism of coal spontaneous combustion inhibition by degradation of white-rot fungus

To investigate the mechanism of inhibition of spontaneous combustion of coal by degradation of white-rot fungus, the changes of macroscopic oxidizing characteristics and microstructure of the degraded coal were investigated by the programmed temperature-raising test and the in situ Fourier-transform infrared spectroscopy experiments. The difference in gas production between the degraded coal and the blank samples indicated that the degradation inhibited the oxidation process of coal, and the intensity of the inhibition effect was different at different oxidation stages. The strongest inhibition effect was found in the accelerated oxidation stage, i.e. 80–140 °C. To further analyze the micro-mechanism of the degradation of Phanerochaete chrysosporium affecting the spontaneous combustion of coal, the relative contents of active functional groups in coal samples were compared. The results showed that the degradation affected the relative contents of hydroxyl, aliphatic hydrocarbon, and oxygenated functional groups in coal. Among them, the most significant changes of –OH and –CO- were observed at 80–140 °C. Thus, it was analyzed that Phanerochaete chrysosporium could degrade the macromolecular structure of coal by generating biological enzymes to reduce the number of oxidizable functional groups such as –OH, –CH2, –CH3, –CO-, and so on, thus reducing the risk of spontaneous combustion of coal.

Wastewater treatment from a typical multisystem hospital using chemically modified banana peels: Taguchi parametric optimization and characterization

The study aims to develop an eco-friendly solution for addressing contaminants in hospital wastewater. To achieve this, banana peel, a cost-effective and easily available agricultural waste, was chemically modified using sulfuric acid and sodium hydroxide. The hospital wastewater was analyzed using an Atomic Absorption Spectrometer to identify the presence of heavy metals. The physicochemical properties were measured and compared against the standards set by the World Health Organization (WHO). Scanning electron microscopy and Fourier-transform infrared spectroscopy were used to characterize the chemically modified banana peel. Batch adsorption was conducted with the wastewater using the prepared adsorbent. The effect of contact time, mixing rate, temperature, and adsorbent dosage was examined to know the removal efficiency of the adsorbent. The experimental design incorporates Taguchi OA design to optimize the process. The total heavy metals discovered in the wastewater were As, Cd, Fe, Cu, Ni, Cr, Pb, Mn and Zn. The percentage of Cd, Fe, Cu, Ni, Cr and Pb removed were 79.5%, 87.9%, 56.9%, 89.0%, 88.5% and 93.5%, respectively, at temperature, adsorbent dosage, mixing rate and contact time of 30 °C, 3 g, 700 rpm and 60 min, respectively. The physicochemical properties remain within the acceptable WHO range except the turbidity. At optimum point, the percentage removal of Cd, Fe, Cu, Ni, Cr, Pb and Zn were 64.3%, 80.5%, 51.4%, 82.3%, 72.4%, 86.6% and 72.1%, respectively; while, the conductivity, pH, TDS, and turbidity value were, respectively, 20.57 mS/cm, 6.8, 10.16 mg/l, and 86.31 NTU. Characterization revealed the existence of active functional groups on the adsorbent surface enhancing the hospital wastewater treatment and change in its morphological structure after the treatment was noticed. In conclusion, the modified banana peel was effective for the treatment of hospital wastewater.

Precisely adjusting the interface adhesion of carbon fiber/epoxy composites by regulating the micro-configuration of graphene oxide nanosheets on the fiber surface

Different micro-configurations of graphene oxide (GO) nanosheets on the carbon fiber (CF) surface, including the distribution and size, endow CF-GO enhanced microstructure and physiochemical characteristics of the CF/epoxy (CF/EP) composites. In order to investigate the relationship between the GO micro-configuration and the interfacial adhesion of the CF/EP, here, polyether imide (PEI)-GO heterogeneous reinforcement was grafted onto the CF surface (CF-PEI-GO) by precisely modulating the mass ratio of CFs to GO. The micro-configuration and properties of the CF-PEI-GO hybrids, together with the thickness and modulus variation of the interface layer are investigated, in order to make certain on the enhancement mechanisms of both interfacial and mechanical performances. Optimal performances of the CF-PEI-GO/EP composites are achieved with a CF/GO mass ratio of 40:1. The uniformly “upright” distribution of moderate-size GO on the CF surface induces a synergistic effect of improved mechanical interlocking, chemical bonding, high wettability, and effective interface adhesion, which are stemmed from higher surface roughness, more active functional groups, higher surface energy, and wider interface thickness with gradient descent modulus. This work presents a valid, practical strategy to precisely control the interfacial adhesion of the CF/EP composites by adjusting the micro-configuration of 2D materials on the fiber surface.

Study on the secondary oxidation behavior and microscopic characteristics of oxidized coal gangue.

Spontaneous combustion of coal gangue (CG) hills has caused varieties of secondary disasters that seriously endanger the ecological environment of the world. The emission law of index gases and their oxidation kinetics during the secondary oxidation process of CG with different ranks of oxidation were studied by using the temperature programmed device and online mass spectrometer (MS). Fourier transform infrared spectroscopy (FTIR) was used to reveal the changes of the CG internal active functional groups. The results showed that the energy required for the combustion of CG with low rank of pre-oxidation was significantly lower than that of the raw sample. However, as the oxidation rank increased, due to amounts of volatile components were released in the process of oxidation reaction, the CG in the combustion process of the emission of index gases and its oxygen consumption rate gradually reduced; the rapid oxidation stage shifted to the direction of the high temperature. In this study, the risk of spontaneous combustion of CG after oxidation at 80℃ under 3% oxygen concentration was the strongest. The results of this paper are of great guiding significance for exploring the spontaneous combustion characteristics of CG hills and their prevention by traditional covering method.

Dispersive micro-solid phase extraction (D-μSPE) of nickel on activated nanodiamonds@Bi2WO6 nanocomposite from water and food samples

This study presents an original nano-sorbent using activated nanodiamonds@Bi2WO6 to separate and enrich nickel ions from water and food samples. FTIR, XRD, FE-SEM, FE-SEM-EDX, EDS-TEAM, TGA, and BET were used to characterize the nanocomposite. It has a large surface area, active functional groups, and better reactivity. Ni(II) ions were determined as Ni(II)-PADAP chelates using UV-VIS spectroscopy. The parameters were studied and optimized, including pH (6), eluent type and volume (1 mL), ligand quantity (10 μg), sorbent dosage (20 mg), and contact time (1 min). The method has a low limit of detection (LOD) of 1.6 μg L−1, a limit of quantification (LOQ) of 5.3 μg L−1, a relative standard deviation of 4.5%, and a preconcentration factor of 10. The method was validated by applying to certified reference materials (BCR estuarine water 505 and 1573a NIST). The method was successfully applied to tap waters, industrial waste waters, and vegetables.

Polyethylene glycol diacid and jeffamine nanocomposites for high-energy supercapacitor with photoluminescence properties

Polymer dots improve ion transport and supercapacitor properties due to active functional groups on their surface. In this study, a new nanocomposite of polymer dot based on polyether amine D-230) Jeffamine (-nickel oxide (PDJA-NiO) was synthesized by a one-step method (quantum yield of 82.2 %). Also, a novel nanocomposite of polymer dot based on polyethylene glycol diacid and Jeffamine-nickel oxide (PDPJA-NiO) was synthesized in the same method and conditions to study the effect of polymers in improving the supercapacitor properties, (quantum yield of 78.84 %). The PDJA-NiO electrode and the PDPJA-NiO electrode were prepared, and the electrochemical analyses were performed. The new PDPJA-NiO specific capacitance and the new PDJA-NiO specific capacitance were obtained at about 527 F g−1 and 355 F g−1 at 1 A g−1. Also, two symmetric devices were made from the PDPJA-NiO nanocomposite (PDPJA-NiO/AC//AC/PDPJA-NiO) and the PDJA-NiO nanocomposite (PDJA-NiO/AC//AC/PDJA-NiO), that showed a specific capacitance of 123 F g−1 and 100 F g−1 at 1 A g−1, respectively. The PDPJA-NiO/AC//AC/PDPJA-NiO and the PDJA-NiO/AC//AC/PDJA-NiO supercapacitors exhibited maximum energy densities of 37.26 Wh kg−1 and 31.01 Wh kg−1. The illumination of white LED by both nanocomposites confirms the practical application of both nanocomposites.

Bacterial biota associated with the invasive insect pest Tuta absoluta (Meyrick)

Tuta absoluta (the tomato pinworm) is an invasive insect pest with a highly damaging effect on tomatoes causing between 80 and 100% yield losses if left uncontrolled. Resistance to chemical pesticides have been reported in some T. absoluta populations. Insect microbiome plays an important role in the behavior, physiology, and survivability of their host. In a bid to explore and develop an alternative control method, the associated microbiome of this insect was studied. In this study, we unraveled the bacterial biota of T. absoluta larvae and adults by sequencing and analyzing the 16S rRNA V3-V4 gene regions using Illumina NovaSeq PE250. Out of 2,092,015 amplicon sequence variants (ASVs) recovered from 30 samples (15 larvae and 15 adults), 1,268,810 and 823,205 ASVs were obtained from the larvae and adults, respectively. A total of 433 bacterial genera were shared between the adults and larval samples while 264 and 139 genera were unique to the larvae and adults, respectively. Amplicon metagenomic analyses of the sequences showed the dominance of the phylum Proteobacteria in the adult samples while Firmicutes and Proteobacteria dominated in the larval samples. Linear discriminant analysis effect size (LEfSe) comparison revealed the genera Pseudomonas, Delftia and Ralstonia to be differentially enriched in the adult samples while Enterococcus, Enterobacter, Lactococcus, Klebsiella and Wiessella were differentially abundant in the larvae. The diversity indices showed that the bacterial communities were not different between the insect samples collected from different geographical regions. However, the bacterial communities significantly differed based on the sample type between larvae and adults. A co-occurrence network of significantly correlated taxa revealed a strong interaction between the microbial communities. The functional analysis of the microbiome using FAPROTAX showed that denitrification, arsenite oxidation, methylotrophy and methanotrophy as the active functional groups of the adult and larvae microbiomes. Our results have revealed the core taxonomic, functional, and interacting microbiota of T. absoluta and these indicate that the larvae and adults harbor a similar but transitory set of bacteria. The results provide a novel insight and a basis for exploring microbiome-based biocontrol strategy for this invasive insect pest as well as the ecological significance of some of the identified microbiota is discussed.

Adsorption Potential and Mechanism of Sludge-Based Activated Carbon Modified with Fly Ash for Removal of Heavy Metals

The treatment of sludge has received a lot of attention due to its intractable status and potential resource value. In order to explore methods of sludge resource utilization and to reduce the harm of heavy metals in municipal sewage, this study analyzed the preparation method of a modified sludge adsorbent (MSA). Another common waste (fly ash) was added to raw domestic sludge (RDS) in a certain proportion and developed to have the ability to adsorb heavy metals through multiple steps such as drying, mixing, activation and carbonization. The adsorption performance of the modified sludge adsorbent (MSA) was verified by simulating wastewater containing Cu2+ and Cd2+, and the surface and structural properties were studied from a microscopic perspective with the aid of SEM and XRD. This study showed that the MSA was characterized by increased microporosity, an enlarged surface area and enhanced activity of functional groups, and the best performance for heavy metal adsorption was found when the RDS was mixed with fly ash at a ratio of 4:3 and a pH of 8. The highest removal rates for the heavy metals Cu2+ and Cd2+ were 99.6% and 99.7%, respectively. The adsorption kinetics and adsorption isotherms indicated that the adsorption behavior of the MSA was controlled by both physical and chemical adsorption, and the best fit of the Langmuir adsorption isotherm model revealed the predominance of monolayer adsorption. The present study is a meaningful exploration of the resource utilization of sludge and fly ash and can provide a cheaper and more effective material for addressing heavy metal pollution in domestic sewage.

Microstructural investigation and performance of carbon matrix composites developed through facile pitch modification route

Increasing demand of high-performance materials lead to development of composites with affordable cost and processing route. Present work involves facile chemical modification (nitric acid and melamine) route to produce carbon matrix composites exhibiting progressive performance. Modified pitches and resultant carbon matrix composites were characterized by FTIR, optical microscopy, SEM, XRD, TGA, TMA, tribological study and compression strength. Chemical treatment given to pitch imparts active functional groups which help to improve affinity between pitch particles. Additionally, to evaluate influence of high temperature treatment, composites were also heated to 1400 °C. Optical images show that microstructure of carbonized (1000 °C) and further heat-treated (1400 °C) composites contain fine isotropic grains and flow domains, attributed to the effective influence of chemical modification. SEM images and Raman spectroscopy also confirmed the similar results of arrangement of carbon layers. TGA analysis revealed that heat-treated composites with acid modified pitch have better thermal stability at 800 °C in zero air. Coefficient of thermal expansion of all composites was measured and found very low i.e. 5 to 10 ppm/°C. Chemical treatment applied to the pitch yielded improved results for tribological performance, coupled with enhanced compressive strength. Notably, up until the present, it was difficult to find reports on fabrication of carbon matrix composites from chemically modified pitch.