Lactone Groups Research Articles

Carbon monoxide+ammonia coupling denitration at low temperatures over manganese–cerium/activated carbon catalysts

To identify the mechanism of the low-temperature CO + NH3 coupling selective catalytic reduction (SCR) denitration process, a series of Mn–Ce/activated carbon catalysts differing in the Ce content were prepared and characterized via SEM, EDS, XRD, XPS, FTIR and evaluated in the CO + NH3 coupling SCR denitration. The results show that the denitrification rates of Mn-Ce/AC catalysts are in the order of 7Mn-3Ce/AC > 7Mn-5Ce/AC > 7Mn-1Ce/AC at a temperature range of 150 °C–300 °C and an oxygen content of 9%. A moderate Ce content provides a smooth catalyst surface with a homogeneous distribution of metal particles and pores, resulting in the optimization of the physical and chemical performance of the Mn-based catalyst. As a result, more active oxygen species and lattice defects are formed, which promoted the dispersion of active components on the catalyst surface, increased the adsorption sites of CO and NH3, and provided more active sites for denitration reaction. Mn4+ and Ce3+ both increased to varying degrees, and oxygen-containing functional groups carboxyl and lactone groups increased, which promoted the synergistic reaction between MnCe, enhancing the NO adsorption and conversion rate. At 150 °C–250 °C, the CO + NH3 coupling denitration is mainly governed by physical adsorption, whereas chemical adsorption is the predominant mechanism at 250 °C–300 °C. The denitration process includes four stages: reaction gas adsorption, adsorption molecular dissociation, catalytic denitration of metal active components and product desorption.

Directional regulation and mechanism analysis of the surface properties of hydrothermal carbon by circulating liquid in the hydrothermal carbonization procedure

The complexity of the chemistry behind the hydrothermal conversion is enormous. Components interact with their own physical and chemical structure, making it harsh to understand the conversion as a whole. Herein, the six-water recirculation and loading nano SiO2 experiment in a one-pot hydrothermal carbonization procedure was designed to elucidate the mechanism of regulating the functional groups and microporous structure of the hydrochar surface. The hydrochar prepared by the second circulating liquid and loading nano-SiO2 (HBC-R2/Si) was equipped most enriched functional groups (carboxyl = 11.48 μmol/g, phenolic hydroxyl = 52.98 μmol/g, lactone groups = 46.52 μmol/g) and suitable pore size (1.90 nm–1.93 nm) as a sorbent riched in hemicellulose. The sorption kinetics (equilibrium reached ≈ 480 min) are approximately evenly fitted by the pseudo-second-order, Weber and Morris, and Elovich models, indicating that membranes and particles diffusion, pore diffusion, and surface sorption coexisted in the sorption of methylene blue (MB) on the hydrochar materials. Simultaneously, all hydrochar materials achieved over 25% MB removal within 90 min (liquid membrane diffusion) and over 40% for HBC-R2 and HBC-R2/Si, suggesting that liquid membrane diffusion is the predominant rate-limiting step. Pearson's correlation analysis and Mantel's analysis announced that the cation exchange capacity (CEC), pore size, and carboxyl groups on the hemicellulose affect the sorption capacity by limiting the pore diffusion procedure. However, the CEC and the phenolic hydroxyl groups on the cellulose and hemicellulose affect the sorption rate by limiting membrane diffusion. Three consecutive sorption/desorption cycles confirmed the high stability and reusability of HBC-R2/Si composites.

Mesomorphic property and gelation ability of rod-shaped compounds having a coumarin skeleton

ABSTRACTRod-shaped liquid crystal materials with a lactone group at the terminal position of the molecule were designed, synthesised and their mesomorphic properties in bulk state and gelation ability in several organic solvents were examined. The effects of perfluoroalkyl chain and chemical structure on liquid crystal property and gelation ability were investigated. These compounds showed smectic A phase in bulk state and gelation ability in polar organic solvents. It was found that the presence of perfluoroalkyl chain and the direction of orientation of the esters had a great effect on these properties.

Efficient adsorption of ammonia on activated carbon from hydrochar of pomelo peel at room temperature: Role of chemical components in feedstock

Activated carbon derived from the organic solid waste is a promising material for ammonia removal. The components in the feedstock would affect the performance of activated carbon, but the detailed effect mechanism remains unknown. To reveal the correlations between the components of the feedstock and different ammonia adsorption styles of activated carbon, this study used pomelo peel to prepare ZnCl2-loaded activated carbon for ammonia adsorption via hydrothermal carbonization and KOH activation, focusing on the effect of the chemical components (cellulose, xylan, pectin, and lignin) on the physicochemical properties and adsorption performance of activated carbon. For raw activated carbon in moist conditions, ammonia was mainly adsorbed in the form of Lewis/Brønsted acid-base (37.8 mg/g), followed by the ZnCl2 coordination compound and organic amine forms (22.3 mg/g). Lignin-added activated carbon had the highest adsorption capacity, 91.2 mg/g in moist conditions, followed by cellulose-added and xylan-added activated carbon. The presence of lignin was beneficial for the formation of the phenolic group of activated carbon (increased by 111.3%), which promoted ammonia adsorption in the form of Lewis acid-base, especially in dry condition. Cellulose and xylan enhanced the formation of carboxylic (i.e., increased by 53.0% for cellulose) and lactonic groups (i.e., increased by 73.4% for cellulose) of activated carbon, leading to an increase of ammonia adsorption in the form of Brønsted acid-base and organic amines in moist conditions. The results illustrated the detailed effect of the chemical components in the feedstock on the ammonia adsorption styles, which could guide the selection of appropriate materials to prepare activated carbon for highly efficient ammonia adsorption under various situation.

Key properties identification of biochar material in anaerobic digestion of sewage sludge for enhancement of methane production

Owing to the intricate physicochemical characteristics of biochar material, a comprehensive understanding of their effects and mechanisms involved in anaerobic digestion still needs to be explored. In this study, the methane yield of sludge hydrolysate was inhibited by 13.3% after the addition of granular activated carbon (GAC), which was due to the predominance of non-selective adsorption by GAC. Whereas the shortened lag phase time (38.2%), the improved methane production rate (16.6%), and the increased methane yield (7.6%) were achieved after the algal biochar (ABC) addition. The methanogenic improvements by ABC were attributed to its redox capacity other than pH buffering capacity. Quantitative results showed that the content of phenolic and lactonic groups were 4.8 and 2.3 times higher than that of GAC, respectively, which endowed ABC with a stronger redox capacity, especially electron-donating capacity. Surface oxygen-containing functional groups like phenolic and lactonic groups of biochar material should be valued for the improvement of anaerobic digestion. The findings of this study provided a comprehensive insight into the connection between mechanisms and related biochar properties during the anaerobic digestion of sewage sludge, which also provided an important clue to selecting, even harnessing desirable biochar material for a given biotechnological process.

Functional surface homogenization of nanobiochar with cation exchanger for improved removal performance of methylene blue and lead pollutants

Biochar materials are good examples of sustainable adsorbents with appreciable recent interests and applications in water treatment. The disadvantage of using unmodified pristine biochars in water treatment is mainly related to the inhomogeneous distribution of various surface functional groups. Therefore, the current study is designed to functionalize and homogenize the surface of a selected nanobiochar with a cation exchanger using hydrothermal and solvothermal microwave irradiation. The adsorption behavior of immobilized Amberlite cation exchanger onto Cynara scolymus nanobiochar (ACE@CSNB) was compared versus the pristine Cynara scolymus nanobiochar (CSNB). ACE@CSNB was categorized as a typical mesoporous material (mean pore size = 2.238 nm) and the FT-IR spectra confirmed surface modification via two characteristic peaks at 1140–1250 cm−1 and 1030–1070 cm−1 for R-SO3− with S = O. The TPD–MS analysis of CSNB and ACE@CSNB referred to the presence of carboxyl, lactonic, and acid anhydride groups as well as phenolic moieties. The adsorption behavior of methylene blue dye and lead ions by ACE@CSNB was found much higher than those concluded by CSNB providing maximum adsorptive capacity values owing to the played clear role by Amberlite cation exchanger. Moreover, ACE@CSNB was efficiently regenerated and confirmed MB and Pb(II) removal with 92.26% and 1000 µmol g−1, respectively Finally, the removal efficiency values from three water matrices by ACE@CSNB biochar were characterized as 91.74–98.19% and 96.27–99.14% for Pb(II) and MB, respectively to refer to the validity and applicability of the investigated ACE@CSNB biochar for treatment of these two pollutants from real water samples with excellent efficiency.Graphical

Optimal schemes for the use of anthelmintics at gastrointestinal strongylatosis of young cattle

The purpose of the research is to study the rational terms for the use of anthelmintics in case of gastrointestinal strongylatoses of young cattle in Nonchernozem zone of the Russian Federation.Materials and methods. The timing of the onset of re-isolation of nematode eggs with feces of cattle after the use of some anthelmintics was determined on 50 black-motley calves weighing 117–130 kg, spontaneously infected with gastrointestinal strongylates. The optimal schemes for the use of anthelmintics in case of gastrointestinal strongylatosis of young cattle were studied on 109 calves of the first year of grazing in the pasture period of 2010. After numbering, the animals were weighed and divided into experimental and control groups. Each group was divided into two subgroups of 15–17 heads. Animals of all groups from May 3 to October 10, 2018 were grazed together in one herd on a pasture where cattle infected with strongylates had previously grazed. Levamisole from the group of imidothiazoles, Alben from the group of benzimidazoles and Aversect-2 from the group of macrocyclic lactones were tested. The drugs were used in therapeutic doses: levamisole at a dose of 7.5 mg/kg by AS intramuscularly, Alben at a dose of 7.5 mg/kg with concentrated feed, and Aversect-2 at a dose of 0.2 mg/kg subcutaneously once. Levamisole was administered to the animals of the first group on the 6th, 10th and 14th weeks of grazing, and to the animals of the second group - on the 6th and 10th weeks of grazing. Alben was used on young cattle of the third group on the 6th, 11th and 16th weeks, and on the animals of the fourth group - on the 6th and 11th weeks of grazing. Aversect-2 was administered to cattle of the fifth group at the 6th, 13th and 20th weeks of grazing, and to the animals of the sixth group – at the 6th and 13th weeks. Animals of the 7th group did not receive the drug and served as control. Fecal samples were taken from animals of all groups on a monthly basis and investigated by a quantitative method in order to detect eggs of gastrointestinal strongylate. The results obtained were statistically processed using the computer program Microsoft Excel.Results and discussion. Tests of drugs for gastrointestinal strongylatoses of young cattle showed different persistence of anthelmintic action. After deworming the animals, single eggs of strongylate in their faeces were again detected 4 weeks after the administration of Levamisole, 5 weeks after the administration of Alben, and 7 weeks after the administration of Aversect-2. The most rational scheme for deworming young cattle with gastrointestinal strongylatoses is the use of Aversect-2 on the 6th and 19th weeks of grazing.

Incidence and Hematological Changes in Dogs Infected with Dirofilaria immitis in Thailand

Dirofilaria immitis is responsible for heartworm disease in dogs. Clinical signs are non-specific, ranging from asymptomatic to severe symptoms. The most common symptoms include coughing, emaciation, dyspnoea, and sudden loss of consciousness. Therefore, diagnosing heartworm infection in dogs requires a combination of methods, such as hematology and serology. This study was conducted on dogs with clinical signs, including anorexia, coughing, panting, and hind legs weakness, that was referred accidentally to a pet clinic in Thonburi district, Bangkok Province, Thailand, during 2020-2022. The examination was performed using a rapid enzyme immunoassay test and a thin blood smear. The total number of dogs admitted to a pet clinic during that period was 980. The result indicated infection of 21 (12 male and 9 female) dogs with heartworm (2.14%). The mean age of dogs was 5.62 ± 2.48 years. All infected dogs were classified under an open husbandry system that did not consistently use heartworm prevention products such as the macrocyclic lactone group. In the groups that received topical ectoparasites products, 10 dogs were detected with heartworm infection. The hematological changes in the infected dogs consisted of leucocytosis and increased levels of ALT, BUN, and creatinine. The study results can guide owners in choosing products that can prevent heartworm. Anti-mosquito nets should be deployed in areas where pets live, and always keep the environment clean.

Investigating the Effects of Nitric Acid Treatments on the Properties of Recycled Carbon Fiber.

In this study, the chemical state change of recycled carbon fiber (rCF) surfaces and the mechanism of the oxygen functional groups according to nitric acid treatment at various times and temperatures were investigated to upcycle the carbon fiber recovered from used carbon composite. When treated with nitric acid at 25 °C, the carbon fiber surface demonstrated the same tensile properties as untreated carbon fiber (CF) for up to 5 h, and the oxygen functional group and polar surface energy of C-O (hydroxyl group) and C=O (carbonyl group) increased slightly compared to the untreated CF up to 5 h. On the other hand, at 100 °C, the tensile properties slightly decreased compared to untreated CF up to 5 h, and the amount of C-O and C=O decreased and the amount of O=C-O (lactone group) started to increase until 1 h. After 1 h, the amount of C-O and C=O decreased significantly, and the amount of O=C-O increased rapidly. At 5 h, the amount of oxygen functional groups increased by 92%, and the polar surface energy increased by 200% compared to desized CF. It was determined that the interfacial bonding force increased the most because the oxygen functional group, O=C-O, increased greatly at 100 °C and 5 h.

Ru-MnOx Interaction for Efficient Hydrodeoxygenation of Levulinic Acid and Its Derivatives.

Metal-oxide interaction was widely observed in supported metal catalysts, playing a significant role in tuning the catalytic performance. Here, we reported that the interaction of Ru and MnOx was able to facilitate the hydrodeoxygenation of levulinic acid (LA) to 2-butanol with a high turnover frequency (1.99 × 106 h-1), turnover number (4411), and yield (98.8%). Moreover, this catalyst was capable of removing the hydroxymethyl group of lactones and diol with high yields of products. The high activity of the Ru-MnOx catalyst was due to the strong Ru-MnOx interaction, which facilitated reduction of Ru oxide to Ru0 and Mn oxide to Mn2+. The increased fractions of Ru0 and Mn2+ provided metal and Lewis acid sites, respectively, and therefore facilitated LA hydrodeoxygenation. A linear correlation between the hydrodeoxygenation activity of the Ru-MnOx catalyst and [Mn2+]ln([Ru0]) was observed.

The Synthesis of Urolithins and their Derivatives and the Modes of Antitumor Action.

Urolithins are microbial metabolites derived from berries and pomegranate fruits, which display anti-inflammatory, anti-oxidative, and anti-aging activities. There are eight natural urolithins (urolithin A-E, M5, M6 and M7), which have been isolated by now. Structurally, urolithins are phenolic compounds and belong to 6H-dibenzo [b,d] pyran-6-one. They have drawn considerable attention because of their vast range of biological activities and health benefits. Recent studies also suggest that they possess anti-SARS-CoV-2 and anticancer effects. In this article, the recent advances in the synthesis of urolithins and their derivatives from 2015 to 2021 are reviewed. To improve or overcome the solubility and metabolism stability issues, the modifications of urolithins are mainly centered on the hydroxy group and lactone group, and some compounds have been found to display promising results and the potential for further study. The possible modes of antitumor action of urolithin are also discussed. Several signaling pathways, including PI3K-Akt, Wnt/β-catenin pathways, and multiple receptors (aryl hydrocarbon receptor, estrogen and androgen receptors) and enzymes (tyrosinase and lactate dehydrogenase) are involved in the antitumor activity of urolithins.

MACHINE LEARNING-BASED VIRTUAL SCREENING, MOLECULAR DOCKING, DRUG-LIKENESS, PHARMACOKINETICS AND TOXICITY ANALYSES TO IDENTIFY NEW NATURAL INHIBITORS OF THE GLYCOPROTEIN SPIKE (S1) OF SARS-CoV-2

To identify natural bioactive compounds (NBCs) as potential inhibitors of spike (S1) by means of in silico assays. NBCs with previously proven biological in vitro activity were obtained from the ZINC database and analyzed through virtual screening and molecular docking to identify those with higher affinity to the spike protein. Eight machine learning models were used to validate the results: Principal Component Analysis (PCA), Artificial Neural Network (ANN), Support Vector Machine (SVM), k-Nearest Neighbors (KNN), Partial Least Squares-Discriminant Analysis (PLS-DA), Gradient Boosted Tree Discriminant Analysis (XGBoostDA), Soft Independent Modelling of Class Analogies (SIMCA) and Logistic Regression Discriminate Analysis (LREG). Selected NBCs were submitted to drug-likeness prediction using Lipinski’s and Veber’s rule of five. A prediction of pharmacokinetic parameters and toxicity was also performed (ADMET). Antivirals currently used for COVID-19 (remdesivir and molnupiravir) were used as a comparator. A total of 170,906 compounds were analyzed. Of these, 34 showed greater affinity with the S1 (affinity energy < -7 kcal mol-1). Most of these compounds belonged to the class of coumarins (benzopyrones), presenting a benzene ring fused to a lactone (group of heterosides). The PLS-DA model was able to reproduce the results of the virtual screening and molecular docking (accuracy of 97.0%). Of the 34 compounds, only NBC5 (feselol), NBC14, NBC15 and NBC27 had better results in ADMET predictions. These had similar binding affinity to S1 when compared to remdesivir and molnupirvir. Feselol and three other NBCs were the most promising candidates for treating COVID-19. In vitro and in vivo studies are needed to confirm these findings.

Occurrence, distribution and environmental risk of 19 anthelmintic drugs in river water and sediment from the Jinjiang River, China.

This study explored the occurrence and distribution of 19 anthelmintic drugs (ADs) including the benzimidazole group, salicylanilide group, imidazothiazole group, tetrahydropyrimidine group, diphenylsulfide group, macrocyclic lactone group and hexahydropyrazine group in river water and sediment of the Jinjiang River in Sichuan, China, during summer and winter seasons. All targets were detected in river water (up to 74.64 ng L-1) and sediment (up to 1701 ng g-1) samples. The predominant ADs were benzimidazoles regardless of seasons and matrices, accounting for 43-82% of the total anthelmintic abundance. Obvious seasonal variation of AD concentrations in the two matrices was observed, which could be attributed to the seasonality of human and veterinary uses of ADs. Evident spatial variation (urban and rural areas) of ADs in winter was indicative of the influence of anthropogenic activities on the environmental concentration of ADs. Though benzimidazoles accumulated in the water and sediment with the highest concentration among all the ADs, macrocyclic lactones were of the highest risk to non-target organisms through ecological risk assessment, with an RQEcotox value up to 2713. This work contributes to comprehensively assessing the contamination level, ecological level and transmission characteristics of ADs in the environment.

Novel surface carbon–oxygen-groups grafted TiO2 for selective catalytic reduction of NOx by NH3 at low temperature

Activated coke (AC) with has excellent low-temperature NH3-SCR denitration performance due to its abundant surface-active functional groups including carbon species, while it is easy to burn during industrial application. Herein, a novel surface carbon–oxygen-groups grafted TiO2 was constructed by calcining the solid mixture of polyethylene glycol (PEG) and TiO2. The prepared 0.4PEG/0.6Ti catalyst shows good NH3-SCR denitration activity, and its NOx conversion was up to 80 % above 210 °C, while the pure AC exhibited poor activity. Characterization results suggest that the superior catalytic activity of 0.4PEG/0.6Ti catalyst is mainly attributed to the formation of lactone and carboxyl groups, which can promote the adsorption and activation of NO and NH3 species. Furthermore, NH3 as the reactant can also inhibit the decomposition of carbonyl groups due to over-oxidation, thus 0.4PEG/0.6Ti catalyst has good long-term stability. The reaction mechanism study reveals that the NH3-SCR reactions over catalysts follow the E-R and L-H mechanisms. Finally, the desulfurization-regeneration-denitration test (imitated activated coke simultaneous desulfurization and denitrification process) was carried out, and the results confirm that the prepared PEG/Ti catalyst could be regenerated for denitration after desulfurization. We expect that this work can provide some guidance for the design of low-temperature denitration catalysts.

Total Synthesis and Anti-inflammatory Activity of Stemoamide-Type Alkaloids Including Totally Substituted Butenolides and Pyrroles

AbstractTotally substituted butenolide including two tetrasubstituted olefins is a distinct structural motif seen in Stemona alkaloids, but efficient methods for its synthesis are not well developed. As an ongoing program aimed at the collective total synthesis of the stemoamide group, we report a stereodivergent method to give either (E)- or (Z)-totally substituted butenolide from the same intermediate. While AgOTf­-mediated elimination via an E1-type mechanism results in the formation of the kinetic (Z)-tetrasubstituted olefin, subsequent TfOH-mediated isomerization gives the thermodynamic (E)-tetrasubstituted olefin. The pyrrole ring is another important structure found in Stemona alkaloids. The direct oxidation of pyrrolidine rings with MnO2 and careful purification gives the pyrrole groups without isomerization of the stereocenter in the lactone group. These two methods enabled us to synthesize a series of stemoamide-type alkaloids including tricyclic, tetracyclic, and pentacyclic frameworks. The anti-inflammatory activities by inhibition of iNOS expression in macrophage cell line RAW264.7 indicate that the most potent anti-inflammatory compounds without cytotoxicity are protostemonines, which consist of pentacyclic frameworks including the totally substituted butenolide.

Synthesis and antimitotic evaluation of Schiff bases derivatives based on 2-amino-combretastatin

Combretastatins A, B, and D are a group of stilbenes, dihydrostilbenes, phenanthrenes, and macrocyclic lactones that may be found in the bark of the Combretum caffrum tree. Preclinical studies have shown that the lead chemical, combretastatin A-4, is highly cytotoxic and inhibits tubulin polymerisation by interacting with the microtubule's colchicine binding site. The anti-cancer activity of a new series of Schiff bases derived from 2-amino-combretastatin as analogues of combretastatin A-4 (CA-4) was investigated. The structures of the synthesised derivatives were proved using 1 H and 13 C NMR, I.R. spectroscopy and elemental analysis. As tubulin polymerisation inhibitors, several drugs demonstrated excellent anti-proliferative activity. IC 50 values for compounds 8a, 8d, 8c and 8i were 1.6, 1.9, 1.9 and 1.3 µM, respectively. In addition, prepared Schiff bases exhibited anti-proliferative action in several human cell lines derived from various organs, namely, HT-29, MCF-7, and A-549, as well as the non-tumor cell line HEK-273. The Schiff bases substituent at the 2-position of ring A in the combretastatin chemical skeleton may play a significant role in the bioactivity of this group of drugs.

ВПЛИВ НЕКОВАЛЕНТНОЇ МОДИФІКАЦІЇ ВУГЛЕЦЕВИХ НАНОТРУБОК ЗА ДОПОМОГОЮ ПОЛІЕТИЛЕНГЛІКОЛЮ НА ЇХ РОЗПОДІЛ У ПОЛІМЕРНІЙ МАТРИЦІ

In polymer nanocomposites filled with carbon nanotubes, it is very difficult to ensure uniform distribution of nanotubes in the polymer matrix, as well as the stability of this dispersion over time. Therefore, in such systems, over time, due to the strong van der Waals forces of attraction between individual nanotubes, aggregation of filler particles takes place. It leads to a transition from the nano to the micro level of their structural organization. This transition significantly affects the complex of functional properties of polymer nanocomposites filled with carbon nanotubes (CNTs). Therefore, the development of new approaches to the stabilization of nanoparticles in order to prevent their aggregation to create nanocomposite materials with improved functional characteristics is an actual task. The work is devoted to the study of the influence of non-covalent modification of carbon nanotubes on the degree of their distribution in the polymer matrix of polyethylene glycol. The peculiarities of CNT distribution of two types were studied: unmodified and non-covalently modified nanotubes. It was found that unmodified CNTs contained hydroxyl, carboxyl and lactone groups on the surface. The presence of these groups on the surface of CNTs allowed for their noncovalent modification. The analysis of microscopic images revealed that the modified CNTs are more evenly distributed in the polymer matrix than the unmodified nanotubes, which can be explained by the different nature of the interaction between the polymer matrix and the CNT. It is shown that for systems containing modified CNTs, a higher value of fractal dimension is observed, which indicates the formation of more fluffy aggregates with CNTs, while unmodified CNTs tend to form denser aggregates. Modification of CNTs with PEG is a promising method to increase the degree of distribution of nanotubes in the polymer matrix, which will significantly improve the properties of such nanocomposite materials.

MilR3, a unique SARP family pleiotropic regulator in Streptomyces bingchenggensis

Streptomyces bingchenggensis is the main industrial producer of milbemycins, which are a group of 16-membered macrocylic lactones with excellent insecticidal activities. In the past several decades, scientists have made great efforts to solve its low productivity. However, a lack of understanding of the regulatory network of milbemycin biosynthesis limited the development of high-producing strains using a regulatory rewiring strategy. SARPs (Streptomyces Antibiotic Regulatory Proteins) family regulators are widely distributed and play key roles in regulating antibiotics production in actinobacteria. In this paper, MilR3 (encoded by sbi_06842) has been screened out for significantly affecting milbemycin production from all the 19 putative SARP family regulators in S. bingchenggensis with the DNase-deactivated Cpf1-based integrative CRISPRi system. Interestingly, milR3 is about 7Mb away from milbemycin biosynthetic gene cluster and adjacent to a putative type II PKS (the core minimal PKS encoding genes are sbi_06843, sbi_06844, sbi_06845 and sbi_06846) gene cluster, which was proved to be responsible for producing a yellow pigment. The quantitative real-time PCR analysis proved that MilR3 positively affected the transcription of specific genes within milbemycin BGC and those from the type II PKS gene cluster. Unlike previous "small" SARP family regulators that played pathway-specific roles, MilR3 was probably a unique SARP family regulator and played a pleotropic role. MilR3 was an upper level regulator in the MilR3-MilR regulatory cascade. This study first illustrated the co-regulatory role of this unique SARP regulator. This greatly enriches our understanding of SARPs and lay a solid foundation for milbemycin yield enhancement in the near future.

Sustainable alternative for removing pesticides in water: Nanomodified activated carbon produced from yeast residue biomass

The systemic insecticide thiamethoxam (TMX) has been frequently used with the need to intensify agricultural activities and food production. Given the pollution concern, biosorption emerges as an efficient and low-cost treatment. Thus, this work proposes to use the environmentally friendly activated carbon magnetic nanocomposite (YAC-NP) produced with yeast residues from the sugar-alcohol industry for the sorption of TMX in water. YAC-NP and its precursors (NP and YAC) were characterized by X-ray (XRD) and Fourier Transform Infrared (FTIR) spectroscopies to investigate their morphology and interaction with TMX. The Boehm titration informed the predominance of acidic character to YAC by the presence of carboxylic, lactone, and phenolic groups. The YAC-NP pH at the point of zero charge (pHPZC) was 6.05, and the best conditions for TMX sorption by YAC-NP occurred at the 2–7 pH range and 30 min of contact time. Sorption tests were performed using batch procedures at increasing concentrations of TMX (5–100 mg/L) and 1 g/L adsorbent dose. The experimental adsorption capacities (Qexp) for YAC, NP, and YAC-NP were 31.52 ± 1.69, 2.42 ± 0.54, and 12.50 ± 0.33 mg/g, respectively. TMX contents were determined by Ultraviolet–visible Spectroscopy (UV/Vis). The pseudo-2nd-order kinetic equation best fit the experimental data (r2 = 0.9996). Among the eight isotherm models applied to the experimental data, Hill, D-R, Temkin, Toth, and R–P were the models that best described the sorption process. YAC-NP reusability in TMX removal was assessed, and a decrease from 71.87 to 0.69% was observed after 10 adsorption cycles.

Interfacial mechanism of the synergy of biochar adsorption and catalytic ozone micro-nano-bubbles for the removal of 2,4-dichlorophenoxyacetic acid in water

A high-efficiency catalytic ozonation system consisting of NaOH-pretreated rice straw biochar (OHBC) and ozone micro-nano-bubbles (O3-MNBs) was developed to remove 2,4-dichlorophenoxyacetic acid (2,4-D) in water, and the interfacial mechanism was further studied in detail. The removal rate of 2,4-D was improved by 47.0% through the synergy of adsorption and catalytic ozonation in the O3-MNBs/OHBC system (89.0%) compared with the O3-MNBs alone system (42.0%), and the ozone utilization rate was increased from 0.43 mg/mg to 0.66 mg/mg. High performance for 2,4-D removal from water with diverse matrix factors could also be obtained. The many hydroxyl groups (OH) (1.25 mmol/g) on the surface of the OHBC were more powerful than the carboxyl and lactone groups (COOH and COOR) at catalyzing ozone to produce OH according to XPS and Boehm titration results. The theoretical calculations based on density functional theory (DFT) showed that ozone molecules were more readily adsorbed on the surface OH groups due to the relatively high negative adsorption energy (–0.31 eV), and they further extended the two OO bond length from 1.277 Å to 1.303 Å and 1.311 Å, thus promoting its decomposition. The degradation mechanism of 2,4-D included dechlorination, electrophilic substitution, and OH substitution, and the degraded water showed relatively low toxicity.