Application of high valent iron stabilized by a biomimetic carboxylato-containing ligand for aqueous contaminant removal

The utilization of non-heme iron oxo complexes holds promise of a new generation of contaminant remediation technologies. These biomimetic complexes are efficient and comprised of common elements in the environment, however, limited mechanistic understanding of the activation of and substrate oxidation by these complexes is available. Fetpena (tpena = N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate), one of a suite of biomimetic complexes that are available, has been found capable of catalyzing the oxidation of organic contaminants by hydrogen peroxide (H2O2), presumably via formation of the readily accessible [FeIV(O)(tpena)]+ complex and hydroxyl radical (HO•). The work presented in this thesis focuses on the activation of hydrogen peroxide by Fetpena in aqueous solution as well as its use in substrate oxidation. Fetpena solution has been prepared by dissolution of [FeIII2O(Htpena)2](ClO4)4 with at least partial hydrolysis of the μ-oxo-bridged diiron complex into mononuclear Fetpena species and subsequent (de)protonation of the [FeIII(OH)(Htpena)]2+/[FeIII(OH)(tpena)]+ species. The speciation of Fetpena is important due to the structural flexibility of tpena ligand with a detailed speciation model of Fetpena species developed using spectroscopic titration method. Both [FeIV(O)(tpena)]+ and HO• are produced during the reaction of Fetpena and H2O2, upon the lysis of the Fe hydroperoxo species with the production of these oxidants evaluated using a phthalhydrazide chemiluminescence method to distinguish between FeIV and HO•. Results of these studies reveal that the generation of oxidants was accelerated at higher H2O2 concentrations and lower solution pH. The generated reactive oxidants can oxidize a wide range of organic substrates with particular studies of the oxidation of rhodamine B and formic acid described in this thesis. The oxidation ability was found to relate to the protonation state of the ligand with the mechanistic implications explored by investigation of substrate decay and H2O2 consumption. The employment of biomimetic iron complexes has invoked great interest in water treatment with previous attention given by other investigators to the use of iron complexes with tetraamido macrocyclic ligands (FeTAML). The performance of Fetpena/H2O2 has been compared to the extensively investigated FeTAML/H2O2 catalytic system with respect to oxidation of a commercial dye (Rhodamine B) in order to evaluate their relative benefits. FeTAML was found to provide optimal oxidation performance under strongly alkaline conditions and relatively low Fe concentrations while Fetpena provided the highest rate of oxidation at acidic to neutral conditions with the reactivity increasing upon increase in Fetpena concentration. Rationalisation of the differing behaviour of Fetpena and FeTAML is presented

Whole-Genome Sequencing Of Mesorhizobium huakuii 7653R Provides Molecular Insights into Host Specificity and Symbiosis Island Dynamics

Background Evidence based on genomic sequences is urgently needed to confirm the phylogenetic relationship between Mesorhizobium strain MAFF303099 and M. huakuii. To define underlying causes for the rather striking difference in host specificity between M. huakuii strain 7653R and MAFF303099, several probable determinants also require comparison at the genomic level. An improved understanding of mobile genetic elements that can be integrated into the main chromosomes of Mesorhizobium to form genomic islands would enrich our knowledge of how genome dynamics may contribute to Mesorhizobium evolution in general. Results In this study, we sequenced the complete genome of 7653R and compared it with five other Mesorhizobium genomes. Genomes of 7653R and MAFF303099 were found to share a large set of orthologs and, most importantly, a conserved chromosomal backbone and even larger perfectly conserved synteny blocks. We also identified candidate molecular differences responsible for the different host specificities of these two strains. Finally, we reconstructed an ancestral Mesorhizobium genomic island that has evolved into diverse forms in different Mesorhizobium species. Conclusions Our ortholog and synteny analyses firmly establish MAFF303099 as a strain of M. huakuii. Differences in nodulation factors and secretion systems T3SS, T4SS, and T6SS may be responsible for the unique host specificities of 7653R and MAFF303099 strains. The plasmids of 7653R may have arisen by excision of the original genomic island from the 7653R chromosome

Wetting and deposition characteristics of air-assisted spray droplet on large broad-leaved crop canopy

Precision and efficient pesticide spraying is an important part of precision agriculture, banana is a large broad-leaved plant, with pests and diseases, has a high demand for spraying and pest control. The purpose of this study was to clarify the wettability of different pesticides on the banana leaf surface, and the effects of nozzle type and working parameters on the deposition distribution performance under air-assisted spray conditions. The wettability test results of different pesticides on banana leaf surfaces showed that the wettability of the adaxial side was always stronger than that of the abaxial side, the smaller the surface tension of the droplets, the better the wettability on the surface. The spray experiment was carried out on the previously developed air-assisted sprayer with the latest developed intelligent variable spray control system. Three types of nozzles were used to spray with different combinations of working parameters. The deposition distribution performance on the banana leaf surface was obtained by image processing using a self-compiled program. The experimental results show that the nozzle type, wind speed, and spray pressure have significant effects on the deposition distribution performance. Through the study of the interaction and coupling effect of nozzle type and working parameters on the spray droplet deposition distribution on both sides of banana leaves, the results show that under the conditions of hollow cone nozzle, 0.5Mpa spray pressure and 3-5 m/s wind speed, the spray coverage and droplet density are in the optimal state. This is mainly due to the low spray pressure and/or wind speed is not enough to make the banana leaves vibrate and improve the performance of pesticide deposition. excessive spray pressure and/or wind speed will cause large deformation of banana leaves and make them airfoil stable, which reduces the surface deposition performance. It is of great significance for promoting sustainable and intelligent phytoprotection

Enhanced Direct Electron Transfer Mediated Contaminant Degradation by Fe(IV) Using a Carbon Black-Supported Fe(III)-TAML Suspension Electrode System

Iron complexes of tetra-amido macrocyclic ligands (Fe-TAML) are recognized to be effective catalysts for the degradation of a wide range of organic contaminants in homogeneous conditions with the high valent Fe(IV) and Fe(V) species generated on activation of the Fe-TAML complex by hydrogen peroxide (H2O2) recognized to be powerful oxidants. Electrochemical activation of Fe-TAML would appear an attractive alternative to H2O2 activation, especially if the Fe-TAML complex could be attached to the anode, as this would enable formation of high valent iron species at the anode and, importantly, retention of the valuable Fe-TAML complex within the reaction system. In this work, we affix Fe-TAML to the surface of carbon black particles and apply this “suspension anode” process to oxidize selected target compounds via generation of high valent iron species. We show that the overpotential for Fe(IV) formation is 0.17 V lower than the potential required to generate Fe(IV) electrochemically in homogeneous solution and also show that the stability of the Fe(IV) species is enhanced considerably compared to the homogeneous Fe-TAML case. Application of the carbon black-supported Fe-TAML suspension anode reactor to degradation of oxalate and hydroquinone with an initial pH value of 3 resulted in oxidation rate constants that were up to three times higher than could be achieved by anodic oxidation in the absence of Fe-TAML and at energy consumptions per order of removal substantially lower than could be achieved by alternate technologies

Epigallocatechin Gallate Protects against MNNG-Induced Precancerous Lesions of Gastric Carcinoma in Rats via PI3K/Akt/mTOR Pathway

Objective. To evaluate the therapeutic effect of epigallocatechin gallate (EGCG) on precancerous lesions of gastric carcinoma (PLGC) and to determine whether EGCG protects against PLGC by regulating PI3K/Akt/mTOR pathway. Methods. Twenty-four male Wistar rats were randomly divided into 3 groups: normal control group (NC), PLGC model group (MC), and group of PLGC rats treated with EGCG (MC + EGCG). 1-Methyl-3-nitro-1-nitrosoguanidine (MNNG) and sodium salicylate were combined and used to establish the PLGC rat animal model. The therapeutic effect of EGCG on PLGC was evaluated by body weight and pathological lesions of gastric mucosa in PLGC rats. Quantitative polymerase chain reaction (qPCR) was applied to measure the mRNA expressions of PI3K, Akt, and mTOR. The protein expressions of cleaved caspase-3, PTEN, PI3K, p-PI3K, Akt, p-Akt, p-mTOR, and mTOR were determined by automated western immunoblotting. Results. The body weight decreased in PLGC rats while EGCG significantly increased body weight. The gastric mucosa of PLGC rats exhibited the pathological lesions of atrophy, intestinal metaplasia, and atypical hyperplasia while EGCG could ameliorate the pathological lesions. EGCG could upregulate the expressions of cleaved caspase-3 and PTEN and reduce the expressions of PI3K, Akt, and mTOR. Conclusions. EGCG ameliorated pathological lesions of PLGC and exerted the effect of apoptosis promotion in PLGC rats. The apoptotic pathway triggered by EGCG may be related to inhibition of PI3K/Akt/mTOR pathway. It provided a theoretical basis for the PLGC treatment and gastric cancer prevention

Comparing the clinical efficacy of three surgical methods for cesarean scar pregnancy

Abstract Background We aimed to compare the clinical efficacy of three surgical methods in the treatment of various types of cesarean scar pregnancy (CSP). Methods Herein, 314 cases of CSP were treated in the department of Obstetrics and Gynecology of the First Affiliated Hospital of Gannan Medical University between June 2017 and June 2020. The patients were divided into three groups based on the treatment received: group A (n = 146; curettage by pituitrin combined with ultrasonic monitoring and hysteroscopy-guided surgery), group B [n = 90; curettage after methotrexate (MTX) injection into the local gestational sac], and group C (n = 78; laparoscopic, transvaginal, and transabdominal cesarean scar resection). These groups were divided into three subgroups (type I, type II, and type III) according to the CSP type of the patients. Results The intraoperative blood loss, length of hospital stay, hospitalization cost, menstrual recovery time, and serum β-HCG normalization time were lower in groups A than in groups B or C with type I, II and III CSP (P < 0.05). Operative efficiency and Successful second pregnancy rate were higher in groups A than in groups B or C with type I and II CSP (P < 0.05). But in type III CSP, the complications were more serious in group A than group C. Conclusions Curettage by pituitrin combined with ultrasonic monitoring and hysteroscopy-guided surgery is an effective and relatively safe treatment for patients with type I and II CSP. Laparoscopic surgery is more suitable for type III CSP

The degradation of inosine and guanosine by DM9218.

<p>(a) Control: inosine and guanosine solution without inoculation of bacteria (270 µL of the inosine and guanosine solution was incubated at 37°C for 60 min, after that 30 µL HClO₄ was added, 20 µL of the mixture was analyzed by HPLC). (b) DM9218 living cells were incubated with inosine and guanosine solution for 60 min. (c) Cell-free extracts of DM9218 were incubated with inosine and guanosine solution for 60 min. (d) Cell-free extracts of DM9218 were incubated with inosine and guanosine solution for 120 min. See details in methods.</p