Selective adsorption of Pb (II) and Cu (II) on mercapto-functionalized aerogels: Experiments, DFT studies and LCA analysis

Mercapto-functionalized aerogels (MA-X) were fabricated using γ-mercaptopropyltrimethoxysilane (MPTMS) as a modification reagent to eliminate Pb (II) and Cu (II) ions from wastewater. Mercapto-functionalized aerogel (MA2) with the MPTMS/TEOS molar ratio of 0.5 exhibited the maximum adsorption amounts of 163.99 mg/g for Pb (II) and 172.41 mg/g for Cu (II) in single ion system, respectively. In binary ion system, selective adsorption experiments revealed that the equilibrium adsorption capacity for Cu (II) (161.29 mg/g) was significantly greater than Pb (II) (90.42 mg/g), and the selectivity factor α showed greater selectivity for Cu (II), demonstrating that Cu (II) was more readily adsorbed on MA2. The results showed that adsorption was consistent with pseudo- second order model and Langmuir model. Thermodynamic results demonstrated that adsorption phenomenon was an exothermic reaction that occurred spontaneously. XPS analysis and density functional theory (DFT) simulations showed that the main mechanism for the adsorption of Pb (II) and Cu (II) on MA2 was through coordination chelation of the –SH groups with Pb (II) and Cu (II). DFT calculations showed a lower adsorption energy (Eads) of Cu (II) ( 2.72 eV) with respect to Pb (II) ( 0.80 eV), indicating that Cu (II) was more stably adsorbed on MA2 and more difficult to exchange by Pb (II). In order to determine the environmental impact of the MA2 preparation process, a life cycle assessment (LCA) was conducted and contribution of each material to MA2 production was analyzed. Finally, a strategy that is environmentally friendly and effective has been pro-posed in order to facilitate MA-X adsorbents production and to improve their application for the treatment of heavy metal polluted wastewater

Schiff base functionalized silica aerogels for enhanced removal of Pb (II) and Cu (II): Performances, DFT calculations and LCA analysis

Schiff base silica aerogels (SCA-X) were synthesized using amino-containing organosilanes and salicylic aldehyde as functional monomers with ethyl orthosilicate hydrolysis condensation as carrier. The influence of SCA-X on the adsorption of Pb (II) and Cu (II) under different adsorption conditions was evaluated, including the effect of solution pH, isotherm, kinetics, thermodynamics and adsorption mechanism. The batch adsorption experiments showed that SCA2 had the optimum adsorption capacity for Pb (II) (357.1 mg/g) and Cu (II) (243.9 mg/g), leading to adsorption equilibrium within 120 min and 360 min, respectively. After six adsorption–desorption cycles, SCA2 still possessed satisfactory adsorption for Pb (II) and Cu (II), demonstrating the reusability of the SCA2 adsorbent material. Kinetic studies indicated that the adsorption process could be described by a pseudo- second-order kinetic model, adsorption isotherms were in accordance with the Langmuir model, indicative of monomolecular layer adsorption. Thermodynamics evaluation revealed the nature of the adsorption process was an endothermic spontaneous process. XPS analysis combined with DFT calculations confirmed that the inter- action mechanism between SCA2 and Pb (II) occurred through the coordination between the nitrogen atom donor in the Schiff base and the oxygen atom donor in the benzene ring, while the interaction between SCA2 and Cu (II) occurred mainly through the coordination between the nitrogen atom in the Schiff base and Cu (II). Life Cycle Assessment (LCA) was introduced to analyze the environmental impact of the SCA2 fabrication process and eco-friendly approaches were provided, which eventually provided theoretical evidence for the application of as-prepared material in the handling of heavy metal effluents

Hyers-Ulam-Rassias Stability of Some Additive Fuzzy Set-Valued Functional Equations with the Fixed Point Alternative

Let Y be a real separable Banach space and let CY,d∞ be the subspace of all normal fuzzy convex and upper semicontinuous fuzzy sets of Y equipped with the supremum metric d∞. In this paper, we introduce several types of additive fuzzy set-valued functional equations in CY,d∞. Using the fixed point technique, we discuss the Hyers-Ulam-Rassias stability of three types additive fuzzy set-valued functional equations, that is, the generalized Cauchy type, the Jensen type, and the Cauchy-Jensen type additive fuzzy set-valued functional equations. Our results can be regarded as important extensions of stability results corresponding to single-valued functional equations and set-valued functional equations, respectively

Video Question Answering: Datasets, Algorithms and Challenges

Video Question Answering (VideoQA) aims to answer natural language questions according to the given videos. It has earned increasing attention with recent research trends in joint vision and language understanding. Yet, compared with ImageQA, VideoQA is largely underexplored and progresses slowly. Although different algorithms have continually been proposed and shown success on different VideoQA datasets, we find that there lacks a meaningful survey to categorize them, which seriously impedes its advancements. This paper thus provides a clear taxonomy and comprehensive analyses to VideoQA, focusing on the datasets, algorithms, and unique challenges. We then point out the research trend of studying beyond factoid QA to inference QA towards the cognition of video contents, Finally, we conclude some promising directions for future exploration.Comment: Accepted by EMNLP 202

Adsorption–desorption behavior of malachite green by potassium permanganate pre-oxidation polyvinyl chloride microplastics

Microplastics (MPs) and the typical hydrophilic organic pollutant Malachite green (MG) are frequently detected in sewage treatment plants. Potassium permanganate (KMnO4) pre-oxidation is an economical and effective technology in wastewater treatment. It is important to study the surface physicochemical characteristics of MPs and understand their fate in wastewater treatment plants after pre-oxidation. In this study, Polyvinyl chloride (PVC) MPs were treated by single and composite KMnO4 pre-oxidation with different pH values. After the pre-oxidation treatment, the appearance of Osingle bondMn spectra and surface nanoparticles indicated the oxides (MnO2) were produced on the MPs surface. Moreover, the adhesion of MnO2 is helpful to improve the hydrophilicity and adsorption capacity of MG. The adsorption capacity of pristine PVC for MG was 2.6 mg/g. But the adsorption capacity increased to 7.0 mg/g for single oxidation and 140.7 mg/g for composite oxidation, respectively. The desorption experiment results indicate the pre-oxidation process could reduce the release efficiency of MG from the PVC MPs due to the better binding of surface MnO2 nanoparticles to MG. However, the total desorption capacity is still high. which illustrates that there is a high potential risk of MG which can transfer from the surface of the PVC MPs to the gastrointestinal fluids.publishedVersio

Transformation of \u3ci\u3eFusarium verticillioides\u3c/i\u3e with a polyketide gene cluster isolated from a fungal endophyte activates the biosynthesis of fusaric acid

A large number of bioactive natural products have been isolated from plant endophytic fungi. However, molecular mechanisms for the biosynthesis of these metabolites have lagged behind because genetic and biochemical studies are difficult to perform within many of the endophytes. In this work, we describe our attempt to express a putative mycoepoxydiene (MED) biosynthetic gene cluster in Fusarium verticillioides, which has a well-developed genetic system for the study fungal polyketide biosynthesis. MED was isolated from Phomopsis sp. A123, a fungal endophyte of the mangrove plant, Kandelia candel. It has several unusual structural features and interesting biological activities. Integration of this Phomopsis gene cluster into the F. verticillioides genome led to the biosynthesis of multiple metabolites. The most highly activated metabolite was isolated and its structure was shown by 1D- and 2D-NMR to be fusaric acid, which is a mycotoxin in Fusarium species and is implicated in fungal pathogenesis. Although fusaric acid was isolated more than 70 years ago, its biosynthetic mechanism remains unclear. These transformants produced 30–35 mg fusaric acid per 100 ml culture. The high level production of fusaric acid will greatly facilitate the genetic and biochemical study of its biosynthetic mechanism. Although we have not detected MED or its analogs from the heterologous host, this work represents the first attempt to express a fungal endophytic gene cluster in a Fusarium species

Characterization of the mitochondrial genome of Analcellicampa xanthosoma gen. et sp. nov. (Hymenoptera: Tenthredinidae)

A new genus with a new species of the tribe Hoplocampini of Hoplocampinae was described from China: Analcellicampa xanthosoma Wei & Niu, gen. et sp. nov. Hoplocampa danfengensis G. Xiao 1994 was designated as the type species of the new genus. The characters of Analcellicampa danfengensis (G. Xiao) comb. nov. were briefly discussed. A key to the tribes and known genera of Hoplocampinae was provided. The nearly complete mitochondrial genome of A. xanthosoma was characterized as having a length of 15,512 bp and containing 37 genes (22 tRNAs, 13 protein-coding genes (PCGs), and 2 rRNAs). The gene order of this new specimen was the same as that in the inferred insect ancestral mitochondrial genome. All PCGs were initiated by ATN codons and ended with TAA or T stop codons. All tRNAs had a typical cloverleaf secondary structure, except for trnS1. Remarkably, the helices H991 of rrnS and H47 of rrnL were redundant, while helix H563 of rrnL was highly conserved. A phylogeny based on previously reported symphytan mitochondrial genomes showed that A. xanthosoma is a sister group to Monocellicampa pruni, with high support values. We suggest that A. xanthosoma and M. pruni belong to the tribe Hoplocampini of Hoplocampinae

Desorption of sulfamethoxazole from polyamide 6 microplastics: Environmental factors, simulated gastrointestinal fluids, and desorption mechanisms

Microplastics (MPs) can enrich pollutants after being released into the environment, and the contaminants-loaded MPs are usually ingested by organisms, resulting in a potential dual biotoxic effect. In this paper, the adsorption behavior of Sulfamethoxazole (SMX) on Polyamide 6 (PA6) MPs was systematically investigated and simulated by the kinetic and isotherm models. The effect of environmental conditions (pH, salinity) on the adsorption process was studied, and the desorption behavior of SMX-loaded PA6 MPs was focused on simulating the seawater, ultrapure water, gastric and intestinal fluids. We found that lower pH and solubilization of SMX by gastrointestinal components (bovine serum albumin (BSA), sodium taurocholate (NaT), and pepsin) can reduce the electrostatic interaction between the surface charge of PA6 MPs and SMX. The result will lead to an increase in the desorption capacity of SMX-loaded PA6 MPs in gastrointestinal fluids and therefore will provide a reasonable mechanism for the desorption of SMX-loaded PA6 MPs in the gastrointestinal fluids. This study will provide a theoretical reference for studying the desorption behavior of SMX-loaded PA6 MPs under gastrointestinal conditions.publishedVersio

High-efficiency removal of Pb (II) and Cu (II) by amidoxime functionalized silica aerogels: Preparation, adsorption mechanisms and environmental impacts analysis

In this work, a novel adsorbent was evaluated for eliminating heavy metal ions from water. The cyano-functionalized silica aerogels (ANSA-X) were fabricated by functionalizing silica aerogel with 2-cyanoethyltrie-thoxysilane, and then further by the reaction with hydroxylamine hydrochloride to obtain amidoxime-functionalized silica aerogels (AOSA-X) with a large specific surface area. The FTIR and NMR analysis indicated that cyano was successfully transformed into amidoxime groups. Adsorption experiments showed the adsorption performed well with the Langmuir isotherm, and AOSA3 exhibited the optimum adsorption property with 598.05 mg/g for Pb (II) and 534.10 mg/g for Cu (II). The thermodynamic results indicated that spontaneous endothermic process was the nature of the adsorption. The adsorption rate of AOSA3 was above 86% after five successive adsorption–desorption cycles. XPS analysis and DFT calculations demonstrated that the N and O atoms participated in the chelating adsorption of Pb (II) and Cu (II), and the N atom on the amidoxime groups played a dominant role. Life Cycle Analysis (LCA) evaluated the environmental effect of the preparation of 1 kg AOSA3 adsorbent, identified the environmental factors with high environmental impact, proposed alternative solutions, proved the feasibility of preparing a novel high-efficiency amidoxime-based adsorbent, and provided a guideline for the sustainable mass production of AOSA3 adsorbent. In conclusion, AOSA3 demonstrated to have promising application perspectives in heavy metal effluent treatment

Identification and Characterization of the Anti-Methicillin-Resistant \u3ci\u3eStaphylococcus aureus\u3c/i\u3e WAP-8294A2 Biosynthetic Gene Cluster from \u3ci\u3eLysobacter enzymogenes\u3c/i\u3e OH11

Lysobactor enzymogenes strain OH11 is an emerging biological control agent of fungal and bacterial diseases. We recently completed its genome sequence and found it contains a large number of gene clusters putatively responsible for the biosynthesis of nonribosomal peptides and polyketides, including the previously identified antifungal dihydromaltophilin (HSAF). One of the gene clusters contains two huge open reading frames, together encoding 12 modules of nonribosomal peptide synthetases (NRPS). Gene disruption of one of the NRPS led to the disappearance of a metabolite produced in the wild type and the elimination of its antibacterial activity. The metabolite and antibacterial activity were also affected by the disruption of some of the flanking genes. We subsequently isolated this metabolite and subjected it to spectroscopic analysis. The mass spectrometry and nuclear magnetic resonance data showed that its chemical structure is identical to WAP-8294A2, a cyclic lipodepsipeptide with potent antimethicillin-resistant Staphylococcus aureus (MRSA) activity and currently in phase I/II clinical trials. The WAP- 8294A2 biosynthetic genes had not been described previously. So far, the Gram-positive Streptomyces have been the primary source of anti-infectives. Lysobacter are Gram-negative soil/water bacteria that are genetically amendable and have not been well exploited. The WAP-8294A2 synthetase represents one of the largest NRPS complexes, consisting of 45 functional domains. The identification of these genes sets the foundation for the study of the WAP-8294A2 biosynthetic mechanism and opens the door for producing new anti-MRSA antibiotics through biosynthetic engineering in this new source of Lysobacter