Neutral pH Research Articles

Accelerated manganese(II) removal by in situ mine drainage treatment system without organic substrate amendment: Metagenomic insights into chemolithoautotrophic manganese oxidation via extracellular electron transfer

Mine drainage waters often contain elevated concentrations of toxic metals and can be a source of environmental pollution. Manganese (Mn)-oxidizing bacteria (MnOB), which can oxidize soluble Mn(II) to insoluble Mn(III, IV) under neutral pH conditions, are expected to be a promising biological agent in passive mine drainage remediation. However, the diversity, functionality and applicability of MnOB for mine drainage treatment remain mostly unknown. Given that many mine environments are poor in organic substances, it is necessary to elucidate the functions of MnOB communities that contribute to metal removal without supplementation with extra organic matter. Here, we constructed in situ continuous-flow bioreactors for treating mine drainage containing approximately 20 mg L−1 Mn(II) and 6 mg L−1 zinc (Zn) (II) and operated these bioreactors without amended organic matter. The removal of Mn(II) and Zn(II) ions reached more than 98 % at a hydraulic retention time of 0.5 days. The X-ray diffraction pattern of Mn oxides deposited on the surface of limestone carriers indicated woodruffite-like mineral accumulation in the reactors. Several heterotrophic MnOB were isolated from the bioreactor, and metagenomic analysis revealed a predominance of diverse lineages of heterotrophs, including Elusimicrobiota, which harbored MoxA-like multicopper oxidase genes. Furthermore, the metagenomic analysis also suggested the involvement of gammaproteobacterial species that possessed putative genes for extracellular electron uptake and CO2 fixation. Our findings offer the first insights into the potential for chemolithoautotrophic Mn(II) oxidation processes via electron transfer from Mn(II/III) and application of chemolithoautotrophic and heterotrophic MnOB in mine drainage remediation without supplying organic materials.

Coupling of porosity and diffusive transport in highly reactive systems: Open issues of reactive transport modelling

Mineral precipitation at interfaces between contrasting materials and porewaters decreases the local porosity and consequently reduces transport across the interface. The near-field of waste repositories usually contains reactive interfaces, and the long-term evolution of diffusive transport away from the waste across the near-field is of special interest in this context. Diffusion as well as further mineral reactions significantly slow down when complete porosity clogging is approached, such that any further development is difficult to detect in experiments. But ongoing diffusion, even if very limited, might be significant for relevant times of up to 1 million years. If clogging occurs in clay materials, experimental studies report a much stronger decrease in anion diffusion compared to that of cations or neutral species. Continuum-scale reactive transport codes can predict experimentally observed clogging, but rely on specific implementations based on conceptual assumptions. Typically, the codes calculate porewater-mineral reactions only within a single cell, and they neglect the physical contact of the clogging mineral in one cell with the porewater in an adjacent cell (no inter-cell reactions considered). This can lead to unrealistic model predictions if porosity approaches zero. For instance, neutral pH porewater is permitted to be in contact with clogging cement hydrates in the adjacent cell, and the implied dissolution of the high-pH minerals is not considered anymore. Thus, intrinsically reactive minerals can be converted erroneously into inert, relict phases by such models. We present a new approach that mimics inter-cell reactions. In doing so, clogging is substantially delayed, and no real steady state with the boundary conditions can be attained, in contrast to conventional approaches. Furthermore, we use a dual-porosity reactive transport approach that takes into account the electrostatic effects of charged clay surfaces on diffusion and precipitation, and apply it to concrete-clay interaction. No complete clogging of the pore space occurs, and the predictions well fit experimental data. Modelling studies that predict the separation of a reactive system into two domains by localised full porosity clogging, followed by separate internal equilibration of the domains, are widespread in the literature. This prediction is interpreted as a conceptual artefact of continuum-scale modelling, which should be avoided by allowing for reactions of completely clogged cells with adjacent porewater. For clays, the dual-porosity model may be a viable option in this respect.

Improvement of the photo-Fenton performance at near neutral pH by the addition of tannic acid from tea leaves waste as a complexing agent in the Pb(II) photo-oxidation

<p>IIntroducing tannic acid from tea leaves waste as a complexing agent of Fe(III) into photo-Fenton process to prevent Fe(OH)3 precipitation at pH 7, and further to increase photo-Fenton activity in the near neutral pH for Pb(II) photo-oxidation is systematically addressed. The photo-Fenton process for Pb(II) photo-oxidation involving Fe2+ and H2O2 solutions as well as UV light was conducted by batch technique, both in the absence and present of tannic acid. Furthermore, the optimization of tannic acid concentration, solution pH, and reaction time were also conducted. The research results assign that the addition of tannic acid in the photo-Fenton process for photo-oxidation of Pb(II) is able to considerably enhance the effectiveness at pH 6-8 (near neutral pH). The activity of the tannic acid from tea leaves waste is comparable to the that of the commercial tannic acid. The best condition of Pb(II) photo-oxidation having 10 mg.L-1 in 50 mL of the solution can be reached by using Fe2+ as high 10 mmol.L-1, H2O2 100 mmol.L-1, with the addition of tannic acid as much as 30 mg.L-1 at pH 7 and 60 min of the time that gave about 85% of the photo-oxidation effectiveness. It is also indicated that the Pb(II) photo-oxidation has resulted in the harmless PbO2 solid . Hence, it is obviously assigned that the priceless tea waste could significantly contribute in the improvement of the photo-Fenton performance to prevent environmental pollution.</p>

Black Titanium Oxide/Activated TaS2 Flakes Photoelectrode for Plasmon Assisted Hydrogen Evolution at Neutral pH at High Current Density.

A heterojunction photo-electrode(s) consisting of porous black titanium oxide (bTiO2) and electrochemically self-activated TaS2 flakes is proposed and utilized for hydrogen evolution reaction (HER). The self-activated TaS2 flakes provide abundant catalytic sites for HER and the porous bTiO2, prepared by electrochemical anodization and subsequent reduction serves as an efficient light absorber, providing electrons for HER. Additionally, Au nanostructures are introduced between bTiO2 and TaS2 to facilitate the charge transfer and plasmon-triggering ability of the structure created. After structure optimization, high HER catalytic activity at acidic pH and excellent HER activity at neutral pH are achieved at high current densities. In particular, with the utilization of bTiO2@TaS2 photoelectrode (neutral electrolyte, sunlight illumination) current densities of 250 and 500mA cm-2 are achieved at overpotentials of 433, and 689mV, respectively, both exceeding the "benchmark" Pt. The addition of gold nanostructures further reduces the overpotential to 360 and 543mV at 250 and 500mA cm-2, respectively. The stability of the prepared electrodes is investigated and found to be satisfying within 24 h of performance at high current densities. The proposed system offers an excellent potential alternative to Pt for the development of green hydrogen production on an industrial scale.

Peracetic acid activation by natural magnetite for bisphenol A degradation: Performance and degradation mechanism

Advanced oxidation processes based on activated peracetic acid (PAA) have been widely used in water treatment. In this study, magnetite was first employed in PAA activation for Bisphenol A (BPA) degradation. The results showed that the magnetic/PAA system degraded 94.6 % BPA in 60 min at neutral pH (pH = 6.7), exhibiting a higher rate constant (kobs = 0.051 min−1) than PAA or magnetite alone. X-ray photoelectron spectroscopy (XPS) results proved that ≡Fe(II) and surface hydroxyl group (OOH) were the dominant active sites, which promoted the electron transfer between magnetite, PAA, and BPA. According to the scavenging experiments and electron paramagnetic resonance (EPR) spectrum, the main reactive oxygen species responsible for BPA degradation include organic radicals (CH3COOO), Hydroxyl radical (OH) and singlet oxygen (1O2). The BPA degradation pathway was determined by LC-MS analysis, and the toxicity of the intermediates was evaluated by ECOSAR and wheat seed growth inhibition experiment. In addition, the magnetite/PAA system presented a good adaptability under a wide initial pH range, demonstrating efficient degradation even in the presence of complex matrices such as Cl−, NO3− or humic acid in water bodies while HCO3− and H2PO4− inhibited BPA degradation. This study not only reveals the mechanism of magnetite activating PAA but also provides a new idea for applying magnetite in PAA-based AOPs to remove micropollutants in wastewater.

Defluorination of monofluorinated alkane by Rhodococcus sp. NJF-7 isolated from soil

Microbial degradation of fluorinated compounds raised significant attention because of their widespread distribution and potential environmental impacts. Here, we report a bacterial isolate, Rhodococcus sp. NJF-7 capable of defluorinating monofluorinated medium-chain length alkanes. This isolate consumed 2.29 ± 0.13 mmol L− 1 of 1-fluorodecane (FD) during a 52 h incubation period, resulting in a significant release of inorganic fluoride amounting to 2.16 ± 0.03 mmol L− 1. The defluorination process was strongly affected by the initial FD concentration and pH conditions, with lower pH increasing fluoride toxicity to bacterial cells and inhibiting enzymatic defluorination activity. Stoichiometric conversion of FD to fluoride was observed at neutral pH with resting cells, while defluorination was significantly lower at reduced pH (6.5). The discovery of the metabolites decanoic acid and methyl decanoate suggests that the initial attack by monooxygenases may be responsible for the biological defluorination of FD. The findings here provide new insights into microbial defluorination processes, specifically aiding in understanding the environmental fate of organic semi-fluorinated alkane chemicals.

Gastroesophageal reflux disease as a risk factor of dental hard tissues erosions

Gastroesophageal reflux disease (GERD) is a common chronic disease leading to a spontaneous and regular retrograde flow of gastric and/or duodenal contents into the esophagus. Reflux of the gastric contents into the oral cavity refers to the extraesophageal presentation of the disease, which, in the absence of timely treatment, can result in erosion of dental hard tissue (EDHT) through repeated exposure of the dental tissue to acidic contents. EDHT are non-carious lesions of the dental hard tissues (mainly enamel, and in some cases dentin), induced by a chemical reaction involving acids, which results in demineralization processes. The incidence rates of EDHT in adult patients with GERD are 32.5–51.5%. The EDHT in GERD develops in stages. Initially, the gradual degradation of tooth pelicula happens when it gradually becomes decayed by repeated acidic attacks. The loss of the pelicula results in direct contact of hydrochloric acid refluxate with the enamel surface and initiation of its demineralization at pH < 5.5 with dissolution of hydroxyapatite crystals. Given the high prevalence of GERD in the population, it seems important to update an integrated approach to the treatment of such patients, which involves pharmacotherapy provided by the gastroenterologist, as well as prevention and minimally invasive treatment of presentations in the oral cavity by the dentist. Patients with EDHT due to GERD need to maintain individual oral hygiene (use mouth washes with a neutral pH level, avoid abrasive toothpastes), use remineralization therapy at home applying remogels (Tooth Mousse), and also be observed by a dentist as part of the follow-up care. Minimally invasive treatment by the dentist involves restorations using composite tooth filling materials and ceramic veneers. It is reasonable to empirically use proton pump inhibitors twice a day for 3 months for the direct treatment of GERD in patients with EDHT.

A Novel Dimeric Short Peptide Derived from α-Defensin-Related Rattusin with Improved Antimicrobial and DNA-Binding Activities.

Rattusin, an α-defensin-related antimicrobial peptide isolated from the small intestine of rats, has been previously characterized through NMR spectroscopy to elucidate its three-dimensional structure, revealing a C2 homodimeric scaffold stabilized by five disulfide bonds. This study aimed to identify the functional region of rattusin by designing and synthesizing various short analogs, subsequently leading to the development of novel peptide-based antibiotics. The analogs, designated as F1, F2, F3, and F4, were constructed based on the three-dimensional configuration of rattusin, among which F2 is the shortest peptide and exhibited superior antimicrobial efficacy compared to the wild-type peptide. The central cysteine residue of F2 prompted an investigation into its potential to form a dimer at neutral pH, which is critical for its antimicrobial function. This activity was abolished upon the substitution of the cysteine residue with serine, indicating the necessity of dimerization for antimicrobial action. Further, we synthesized β-hairpin-like analogs, both parallel and antiparallel, based on the dimeric structure of F2, which maintained comparable antimicrobial potency. In contrast to rattusin, which acts by disrupting bacterial membranes, the F2 dimer binds directly to DNA, as evidenced by fluorescence assays and DNA retardation experiments. Importantly, F2 exhibited negligible cytotoxicity up to 515 μg/mL, assessed via hemolysis and MTT assays, underscoring its potential as a lead compound for novel peptide-based antibiotic development.

PH-responsive chitosan hollow microspheres pro-flavor based on interfacial Schiff-base bonding for controlled release of cinnamaldehyde

The strong volatility and instability of cinnamaldehyde (CA) limits its application in food and flavor industry. Combining physical encapsulation techniques and chemical bonding methods is a novel strategy to overcome this challenge. Herein, a cinnamaldehyde-chitosan hollow microsphere pro-flavor (CHMP) was developed through interfacial Schiff-base bonding reaction with an average size of 220∼800 nm. Hydrophilic macromolecules of glycol chitosan (GC) are fixed at the oil/water interface via numerous hydrophobic small molecules of CA, forming the CHMP with a positively charged surface and lipophilic cavity. Thus, physical and chemical double-barrier CA delivery system was fabricated in which CA molecules were chemically linked to GC and at the same time embedded in the particles’ core. This structure endows CHMP excellent stability and pH-responsive release abilities. After 48 d of open storage at room temperature, the retention rate of CA in CHMP powder was above 85%. CA release from CHMP exhibited a sustained release rate at neutral pH and a fast release under acidic condition. CHMP also retained excellent sensory profile and exhibited durable antibacterial performance against both Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Therefore, rather than most of the traditional methods, this CHMP may open a new path for CA controlled release, widening their applications with multifunctionalities.

Interaction of the Polymeric Layer Derived from 3-(4-Trifluoromethyl)-phenyl)-thiophene with Synthetic Stimulants on the Phase Boundary

Modification of an electrode surface with a selective layer leads to amplification of the electrochemical signal. A film derived from electrochemically oxidized 3-(4-trifluoromethyl)-phenyl)-thiophene deposited on a graphite electrode (ThPhCF3/G) was used to estimate the affinity for synthetic stimulants (2-aminoindane, buphedrone, naphyrone) using a combination of square wave voltammetry and electrochemical impedance spectroscopy. The modified surface was characterized using Raman spectroscopy, which confirmed that the presence of the –PhCF3 group is important for the recognition of synthetic stimulants. The determined values of the adsorption constants (Kads) showed the significance of charge–transfer and/or hydrogen bond interactions between—PhCF3 groups in the polymeric film and the analyte of interest: buphedrone (9.79 × 105) < naphyrone (1.57 × 106) < 2-AI (1.87 × 106). Compared to electrodes modified with nanomaterial, PThPhCF3/G-electrodes showed the highest sensitivity in concentration range of 1–11 μmol L−1 at neutral pH and a possibility of detection of 0.43–0.56 μg mL−1 (sr = 0.05–0.12). The analytical performance of ThPhCF3/G promises good perspectives for the detection of synthetic stimulants in forensic samples without prior pretreatment.

Protocatechuic acid enhanced the selective degradation of sulfonamide antibiotics in Fe(III)/peracetic acid process under actually neutral pH conditions

The practical application of the Fe-catalyzed peracetic acid (PAA) processes is seriously restricted due to the need for narrow pH working range and poor anti-interference capacity. This study demonstrates that protocatechuic acid (PCA), a natural and eco-environmental phenolic acid, significantly enhanced the removal of sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions (6.0–8.0) by complexing Fe(III). With sulfamethoxazole (SMX) as the model contaminant, the pseudo-first-order rate constant of SMX elimination in PCA/Fe(III)/PAA process was 63.5 times higher than that in Fe(III)/PAA process at pH 7.0, surpassing most of the previously reported strategies-enhanced Fe-catalyzed PAA processes (i.e., picolinic acid and hydroxylamine etc.). Excluding the primary contribution of reactive species commonly found in Fe-catalyzed PAA processes (e.g., •OH, R-O•, Fe(IV)/Fe(V) and 1O2) to SMX removal, the Fe(III)-peroxy complex intermediate (CH3C(O)OO-Fe(III)-PCA) was proposed as the primary reactive species in PCA/Fe(III)/PAA process. DFT theoretical calculations indicate that CH3C(O)OO-Fe(III)-PCA exhibited stronger oxidation potential than CH3C(O)OO-Fe(III), thereby enhancing SMX removal. Four potential removal pathways of SMX were proposed and the toxicity of reaction solution decreased with the removal of SMX. Furthermore, PCA/Fe(III)/PAA process exhibited strong anti-interference capacity to common natural anions (HCO3−, Cl−and NO3−) and humic acid. More importantly, the PCA/Fe(III)/PAA process demonstrated high efficiency for SMX elimination in actual samples, even at a trace Fe(III) dosage (i.e., 5 μM). Overall, this study provided a highly-efficient and eco-environmental strategy to remove sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions and to strengthen its anti-interference capacity, underscoring its potential application in water treatment.

Intramolecular Disulfide Bridges in Voltage-Dependent Anion Channel 2 (VDAC2) Protein from Rattus norvegicus Revealed by High-Resolution Mass Spectrometry.

Voltage-Dependent Anion Channel isoforms (VDAC1, VDAC2, and VDAC3) are relevant components of the outer mitochondrial membrane (OMM) and play a crucial role in regulation of metabolism and in survival pathways. As major players in the regulation of cellular metabolism and apoptosis, VDACs can be considered at the crossroads between two broad families of pathologies, namely, cancer and neurodegeneration, the former being associated with elevated glycolytic rate and suppression of apoptosis in cancer cells, the latter characterized by mitochondrial dysfunction and increased cell death. Recently, we reported the characterization of the oxidation pattern of methionine and cysteines in rat and human VDACs showing that each cysteine in these proteins is present with a preferred oxidation state, ranging from the reduced to the trioxidized form, and such an oxidation state is remarkably conserved between rat and human VDACs. However, the presence and localization of disulfide bonds in VDACs, a key point for their structural characterization, have so far remained undetermined. Herein we have investigated by nanoUHPLC/High-Resolution nanoESI-MS/MS the position of intramolecular disulfide bonds in rat VDAC2 (rVDAC2), a protein that contains 11 cysteines. To this purpose, extraction, purification, and enzymatic digestions were carried out at slightly acidic or neutral pH in order to minimize disulfide bond interchange. The presence of six disulfide bridges was unequivocally determined, including a disulfide bridge linking the two adjacent cysteines 4 and 5, a disulfide bridge linking cysteines 9 and 14, and the alternative disulfide bridges between cysteines 48, 77, and 104. A disulfide bond, which is very resistant to reduction, between cysteines 134 and 139 was also detected. In addition to the previous findings, these results significantly extend the characterization of the oxidation state of cysteines in rVDAC2 and show that it is highly complex and presents unusual features. Data are available via ProteomeXchange with the identifier PXD044041.

Heparin-Functionalized Bioactive Glass to Harvest Endogenous Growth Factors for Pulp Regeneration.

Pulp and periapical diseases can lead to the cessation of tooth development, resulting in compromised tooth structure and functions. Despite numerous efforts to induce pulp regeneration, effective strategies are still lacking. Growth factors (GFs) hold considerable promise in pulp regeneration due to their diverse cellular regulatory properties. However, the limited half-lives and susceptibility to degradation of exogenous GFs necessitate the administration of supra-physiological doses, leading to undesirable side effects. In this research, a heparin-functionalized bioactive glass (CaO-P2O5-SiO2-Heparin, abbreviated as PSC-Heparin) with strong bioactivity and a stable neutral pH is developed as a promising candidate to addressing challenges in pulp regeneration. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis reveal the successful synthesis of PSC-Heparin. Scanning electron microscopy and X-ray diffraction show the hydroxyapatite formation can be observed on the surface of PSC-Heparin after soaking in simulated body fluid for 12 h. PSC-Heparin is capable of harvesting various endogenous GFs and sustainably releasing them over an extended duration by the enzyme-linked immunosorbent assay. Cytological experiments show that developed PSC-Heparin can facilitate the adhesion, migration, proliferation, and odontogenic differentiation of stem cells from apical papillae. Notably, the histological analysis of subcutaneous implantation in nude mice demonstrates PSC-Heparin is capable of promoting the odontoblast-like layers and pulp-dentin complex formation without the addition of exogenous GFs, which is vital for clinical applications. This work highlights an effective strategy of harvesting endogenous GFs and avoiding the involvement of exogenous GFs to achieve pulp-dentin complex regeneration, which may open a new horizon for regenerative endodontic therapy.

Comparison of dry (air classification) and wet fractionated pea protein on protein molecular structure and gelling properties

AbstractDry fractionation is an environmentally friendly and cost‐effective method to separate protein fractions. While most research has focused on the structure and functional properties of pea protein isolates (PPI), the information on dry fractionated pea protein (DFPP) is limited. This study compared DFPP (protein content (PC): 50.7%, insoluble fiber: 17%), to PPI (PC: 80.1%, insoluble fiber: 8.33%), in terms of the protein structure, solubility, and heat‐induced gelation. SDS‐Page, size‐exclusive chromatographic, and Fourier‐transform infrared spectrophotometer analysis indicated that DFPP contained the major protein components in pea, and their native structures were well maintained. Whereas for PPI, some proteins were lost during wet extraction, and partial protein unfolding and aggregation were observed. At neutral pH, DFPP showed significantly higher solubility (44.64 ± 0.55%) than PPI (12.09 ± 1.42%). Interestingly, DFPP showed good gelling capacity as reflected by lower gelling concentration and higher gel mechanical strength and elasticity compared to those made from PPI. The DFPP gels were twice higher in mechanical strength (7.71 ± 0.21 kPa) than that prepared from PPI at pH 7. Strong gels were also obtained for DFPP at pH 5. The gel morphology revealed phase separation between protein and polysaccharides by heating, with stick‐shaped fiber (10–25 μm) dispersed in the continuous protein networks. Eventually, the polysaccharides including fiber and starch helped strengthen the gel network by acting as fillers. This knowledge will help to expand the applications of DFPP as a gelling ingredient in food formulations, but also allow industry to benefit from the dietary fiber co‐exist in the protein to develop healthier food products using a holistic approach.

Nano Biochar: Properties, Preparation, Key Features and its Impact on Soil and Crop Ecosystem

Nano biochar, a carbon-rich material, is increasingly recognized for its pivotal role in sustainable agriculture and environmental management. It is produced through the pyrolysis of biomass under controlled conditions, converting organic matter into a stable form of carbon. This process effectively sequesters carbon and mitigates greenhouse gas emissions while yielding a valuable soil amendment. In agriculture, biochar offers multifaceted benefits. Its porous structure enhances soil fertility and water retention, fostering optimal conditions for plant growth. By serving as a reservoir for nutrients, biochar promotes their slow release, reducing the risk of leaching and nutrient runoff. Moreover, its neutral pH and high organic carbon content contribute to soil health and microbial activity. Some key features of nano biochar are enhancing surface area and porosity, improved soil fertility, nutrient retention and recycling, slow-release fertilizer, enhanced microbial population, carbon sequestration etc. Furthermore, biochar aids in waste management by utilizing agricultural residues as feedstock. However, despite its promising advantages, biochar application requires careful consideration. Variations in feedstock and production methods can influence its efficacy and environmental impact. Moreover, its long-term effects on soil health and crop productivity warrant further research and field trials. It presents a sustainable solution for enhancing agricultural productivity, mitigating climate change, and managing organic waste. However, its optimal utilization necessitates comprehensive understanding, integrated management practices, and ongoing scientific inquiry.

Unraveling the determinants of antibiotic resistance evolution in farmland under fertilizations

Organic fertilization is a major driver potentiating soil antibiotic resistance in farmland. However, it remains unclear how bacterial antibiotic resistance evolves in fertilized soils and even spreads to crops. Compared with no fertilizer and commercial fertilizer treatments, organic fertilizers markedly increased the abundance of soil antibiotic resistance genes (ARGs) but the relatively weaker transfer of resistance genes from soil to crops. The introduction of organic fertilizers enriches the soil with nutrients, driving indigenous microorganisms towards a K-strategy. The pH, EC, and nutrients as key drivers influenced the ARGs abundance. The neutral (pH 7.2), low salt (TDS 1.4 %) and mesotrophic (carbon content 3.54 g/L) habitats similar to the soil environment conditioned by organic fertilizers. These environmental conditions clearly prolonged the persistence of resistant plasmids, and facilitated their dissemination to massive conjugators soil microbiome but not to plant endophytes. This suggested that organic fertilizers inhibited the spread of ARGs to crops. Moreover, the composition of conjugators showed differential selection of resistant plasmids by endophytes under these conditions. This study sheds light on the evolution and dissemination of antibiotic resistance in farmlands and can aid in the development of antimicrobial resistance control strategies in agriculture.

Efficient Nimesulide degradation via chlorination and sun-simulated radiation: Kinetic insights, reactive species formation, and application to real wastewater

Hypochlorite mediated oxidation had been established as an efficient process for degrading organic pollutants in water. In this research work, it was evaluated the synergistic potential of solar light irradiation combined with hypochlorite on a emerging contaminant model such as Nimesulide (NIM), a nonsteroidal anti-inflammatory drug. These experiments shown that at pH 3.0, where only hypochlorous acid (HOCl) prevails, the degradation constant of NIM exhibited an increase from 2.50 × 10−4 s−1 (under dark conditions) to 1.53 × 10−3 s−1 (sun-simulated radiation), signifying an approximately six-fold acceleration in degradation. Moreover, under approximately neutral pH value (7.5) wherein both HOCl and hypochlorite ion (ClO−) coexist, the enhancement observed was approximately twofold, in particular a mineralization up to 32 % was observed. This investigation also included quenching experiments conducted at varying pH levels, shedding light on the role of specific reactive species and their contributions to the degradation mechanism. The impact of synergistic effect between solar-simulated irradiation and hypochlorite systems on NIM degradation showcases a remarkable kinetic enhancement, particularly evident at lower pH values. The degradation byproducts have been identified via high resolution HPLC-MS and the main ion formed during the reaction have been monitored by IC-MS. Experiments in real sewage treatment plant waters using sun radiation revealed the promising potential and efficiency of this alternative method, despite a comparatively lower degradation rates when compared with UV lamp application. This approach offers a sustainable and economically advantageous solution for wastewater treatment.

High-efficiency removal of diclofenac sodium (DS) drug using chitosan-grafted-poly(acrylic acid-co-N-isopropylacrylamide)/kaolin clay hydrogel composite

ABSTRACT The current study mainly deals with the adsorptive removal of the diclofenac sodium (DS) drug from aqueous solution by the use of the kaolin-CS-g-poly(AA-co-NIPAM) composite. The synthesised composite was characterised by Fourier Transform infrared (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Transmission electron microscopy (TEM), energy dispersive X-Ray spectroscopy (EDS), atomic force microscopy (AFM), swelling % ratio and point of zero charge ( p H PZC ). The pHpzc of the composite was determined to be 4. The maximum adsorption capacity of 18.51 mg/g observed at the optimised conditions, including 0.1 g of kaolin clay dose, at neutral pH using composite dose of 0.06 g for 90 min. The optimum drug concentration was 500 mg/l for temperature of 30°C. Effect of the ionic strength on the adsorption capacity of the composite and its mechanism for DS drug removal has also been investigated. The process of drug adsorption on the prepared composite was chemical and data fits well to the pseudo second order and Langmuir model. Overall, the process was spontaneous and endothermic in nature.

Short-Lived Active Prorenin: Precursor of So-Called Native Prorenin.

The enzymatic activity of the aspartic protease, renin, is critical for its function in blood pressure regulation and sodium homeostasis. Incubation of so-called native prorenin at low pH leads to its activation. After binding to transition-state mimicking renin inhibitors at neutral pH, prorenin attains the active conformation, as indicated by immunosorbent assay using monoclonal antibodies specific for epitopes of the prosegment or the renin body. A comparison of immunosorbent assay with enzyme-kinetic assay revealed the intermediary steps of prorenin auto-activation/inactivation. The kinetically identified intermediary steps of activation/inactivation correspond with the published crystal structures of free renin, free prorenin, and renin in complex with inhibitors. Both renin and activated prorenin exist in 2 forms, α and β. The α form is active, and the α/β quantity ratio is 2.5. The kidney produces renin and prorenin, while the ovarium, placenta, and eye produce inactive prorenin. The production of renin by these organs has never been demonstrated. We propose that the so-called native prorenin in extracellular fluid, including the circulation, is derived, at least partly, from short-lived active prorenin. Its potential paracrine function is discussed.

Global comparison shows that soil bacterial communities in extreme pH soils are more structured by deterministic processes

A major aim of microbial ecology is the search for basic ‘rules’ that dominate variation in microbial communities. An earlier comparison of several soil successional series showed that pH explained variation in the relative importance of stochastic versus deterministic processes in bacterial communities. In neutral pH soils, bacterial communities were more strongly influenced by stochastic processes than in low or high pH soils. Here, we took a broad level approach to attempt a more definitive answer of whether soil pH dominates bacterial community structuring using the global database of 237 samples. The beta-NTI showed that at both a global and continental scale, samples with low pH were dominated by deterministic processes, while in samples at around neutral pH, stochastic processes dominated. At high pH, stochasticity dominated on the global scale, but on several continents, the beta-NTI showed determinism predominating. Overall, it appears that bacterial community structuring is strongly and predictably affected by pH, with the most consistent difference observed between determinism at low pH and stochasticity at neutral pH. There is a need for hypothesis testing to explain why this trend exists. It is possible that at low pH, there is a greater selection for consortia to exploit resources, which leads to more predictable, deterministic combinations of species co-occurring. Additionally, the high energy demands for homeostasis and the constraints from the lack of available nutrient resources may impose greater niche-based competition, resulting in more deterministic community structuring at low pH.