Method for Prioritizing Urban Pesticides for Monitoring

Environmental Monitoring Branch (EM) is to monitor pesticide residues in surface waters with urban runoff inputs. Recent monitoring efforts have identified urban runoff as a major contributor of pesticides to California surface waters (Ensminger et al., 2012). Pesticide use is i

Genetically engineered cell membrane-coated nanoparticles for antibacterial and immunoregulatory dual-function treatment of ligature-induced periodontitis

Purpose: In order to overcome the problem that conventional pharmacological treatments of periodontitis cannot effectively synergizing antimicrobial and immunomodulation, inspired by the critical role of toll-like receptor 4 (TLR4) in bacterial recognition and immune activation, we demonstrated a combined antibacterial-immunoregulatory strategy based on biomimetic nanoparticles.Methods: Functioned cell membranes and silk fibroin nanoparticles (SNs) loaded with minocycline hydrochloride (Mino) were used to prepare a biomimetic nanoparticle (MSNCs). SNs and MSNCs were characterized by Scanning Electron Microscope, size, zeta potential, dispersion index. At the same time, SNs were characterized by cell counting kit-8 and real-time Polymerase Chain Reaction (RT-PCR). TLR4-expressing cell membranes were characterized by RT-PCR and western blot (WB). Cell membrane coating was characterized by Transmission Electron Microscope (TEM), the Bradford staining and WB. Then, Laser confocal, flow cytometry and agar plate coating were evaluated in vitro with antibacterial effects, RT-PCR was simultaneously evaluated with immunoregulatory effects. Finally, Anti-inflammatory treatment of MSNCs was evaluated in a ligature-induced periodontitis (LIP) mouse model.Results: Successfully prepared cell membranes overexpressing TLR4 and constructed MSNCs. In vitro studies had shown that MSNCs effectively targeted bacteria via TLR4 and acted as molecular decoys to competitively neutralize lipopolysaccharide (LPS) in the microenvironment as well as inhibit inflammatory activation of macrophages. In vivo, MSNCs effectively attenuated periodontal tissue inflammation and alveolar bone loss in a LIP mouse model.Conclusion: MSNCs have good targeted antibacterial and immunoregulatory effects, and provide a new and effective strategy for the treatment of periodontitis and have good potential for application in various types of pathogenic bacterial infections

Use-Exposure Relationships of Pesticides for Aquatic Risk Assessment

Field-scale environmental models have been widely used in aquatic exposure assessments of pesticides. Those models usually require a large set of input parameters and separate simulations for each pesticide in evaluation. In this study, a simple use-exposure relationship is developed based on regression analysis of stochastic simulation results generated from the Pesticide Root-Zone Model (PRZM). The developed mathematical relationship estimates edge-of-field peak concentrations of pesticides from aerobic soil metabolism half-life (AERO), organic carbon-normalized soil sorption coefficient (KOC), and application rate (RATE). In a case study of California crop scenarios, the relationships explained 90–95% of the variances in the peak concentrations of dissolved pesticides as predicted by PRZM simulations for a 30-year period. KOC was identified as the governing parameter in determining the relative magnitudes of pesticide exposures in a given crop scenario. The results of model application also indicated that the effects of chemical fate processes such as partitioning and degradation on pesticide exposure were similar among crop scenarios, while the cross-scenario variations were mainly associated with the landscape characteristics, such as organic carbon contents and curve numbers. With a minimum set of input data, the use-exposure relationships proposed in this study could be used in screening procedures for potential water quality impacts from the off-site movement of pesticides

Promoting effect of acid treatment on Pd-Ni/SBA-15 catalyst for complete oxidation of gaseous benzene

A novel Pd-Ni/SBA-15 catalyst synthesized by co-impregnation of Pd and Ni precursors onto porous SBA-15 silica support was used for catalytic removal of gaseous benzene. Compared to original Pd/SBA-15 catalyst, the addition of Ni significantly promoted the catalytic performance. Moreover, with introducing acid treatment, the new Pd-Ni/SBA-15 catalyst showed much better catalytic activity than both Pd/SBA-15 catalyst and original Pd-Ni/SBA-15 catalyst, and the benzene could be completely oxidized into CO2 and H2O at 260 degrees C over the new catalyst at a high space velocity of 12,0000 mL/(g h). (C) 2016 Elsevier B.V. All rights reserved.</p

MnO2-nanowire@NiO-nanosheet core-shell hybrid nanostructure derived interfacial Effect for promoting catalytic oxidation activity

Nanostructure-derived interfacial effect plays a great role in enhancing catalytic activities. Herein, a MnO2 nanowires@NiO nanosheets core-shell hybrid nanostructure was successfully prepared by uniformly decorating NiO nanosheets on the one-dimensional MnO2 nanowires. The physi-chemical properties of the MnO2 and MnO2@NiO were characterized by using XRD, BET, SEM, H-2-TPR and XPS techniques. Compared to the single MnO2 nanowires, the MnO2@NiO nanocomposite with better low-temperature reducibility and more active surface oxygen species exhibited much better performance in complete oxidation of benzene, giving the temperatures for 100% benzene conversion of 320 degrees C under the conditions of 1000 ppm benzene in air and space velocity of 120,000 mL g(-1) h(-1) while the value over pure MnO2 was 380 degrees C. The novel hetero-interface constructed between MnO2 and NiO core-shell nanostructures might make a great contribution on this significantly promoting effect.</p

High reactivity and sintering resistance of CH4 oxidation over modified Pd/Al2O3

High reactivity and sintering resistance are key factors to design outstanding CH4 oxidation noble metal-based supported catalysts. Herein, we prepared and screened 0.5 wt% Pd/Al2O3 (among 0.3-3 wt% Pd loading) samples prepared by wet impregnation with very high CH4 catalytic activity. The hydrophobic modification of gamma-Al2O3 support by triethoxyoctylsilane (TEOOS) exhibits further enhanced activity for CH4 oxidation, ca. T-90 decrease from 375 degrees C to 350 degrees C with enhanced concentration of surface Pd-0 sites. Besides, after Al2O3 protection layer deposition over the 0.5 wt% Pd/Al2O3 by atomic layer deposition (ALD), distinct higher temperature stability due to reduced agglomeration was demonstrated

Mechanism of dichloromethane disproportionation over mesoporous TiO2 under low temperature

Mesoporous TiO2 was synthesized via nonhydrolytic template-mediated sol-gel route. Catalytic degradation performance upon dichloromethane over as-prepared mesoporous TiO2, pure anatase and rutile were investigated respectively. Disproportionation took place over as-made mesoporous TiO2 and pure anatase under the presence of water. The mechanism of disproportionation was studied by in situ FTIR. The interaction between chloromethoxy species and bridge coordinated methylenes was the key step of disproportionation. Formate species and methoxy groups would be formed and further turned into carbon monoxide and methyl chloride. Anatase (001) played an important role for disproportionation in that water could be dissociated into surface hydroxyl groups on such structure. As a result, the consumed hydroxyl groups would be replenished. In addition, there was another competitive oxidation route governed by free hydroxyl radicals. In this route, chloromethoxy groups would be oxidized into formate species by hydroxyl radicals transfering from the surface of TiO2. The latter route would be more favorable at higher temperature. (c) Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature 201

mechanismofdichloromethanedisproportionationovermesoporoustio2underlowtemperature

Mesoporous tio2 was synthesized via nonhydrolytic template-mediated sol-gel route. catalytic degradation performance upon dichloromethane over as-prepared mesoporous tio2, pure anatase and rutile were investigated respectively. disproportionation took place over as-made mesoporous tio2 and pure anatase under the presence of water. the mechanism of disproportionation was studied by in situ ftir. the interaction between chloromethoxy species and bridge coordinated methylenes was the key step of disproportionation. formate species and methoxy groups would be formed and further turned into carbon monoxide and methyl chloride. anatase (001) played an important role for disproportionation in that water could be dissociated into surface hydroxyl groups on such structure. as a result, the consumed hydroxyl groups would be replenished. in addition, there was another competitive oxidation route governed by free hydroxyl radicals. in this route, chloromethoxy groups would be oxidized into formate species by hydroxyl radicals transfering from the surface of tio2. the latter route would be more favorable at higher temperature. (c) higher education press and springer-verlag gmbh germany, part of springer nature 201

Properties and Mechanisms of Flavin-Dependent Monooxygenases and Their Applications in Natural Product Synthesis

Natural products are usually highly complicated organic molecules with special scaffolds, and they are an important resource in medicine. Natural products with complicated structures are produced by enzymes, and this is still a challenging research field, its mechanisms requiring detailed methods for elucidation. Flavin adenine dinucleotide (FAD)-dependent monooxygenases (FMOs) catalyze many oxidation reactions with chemo-, regio-, and stereo-selectivity, and they are involved in the synthesis of many natural products. In this review, we introduce the mechanisms for different FMOs, with the classical FAD (C4a)-hydroperoxide as the major oxidant. We also summarize the difference between FMOs and cytochrome P450 (CYP450) monooxygenases emphasizing the advantages of FMOs and their specificity for substrates. Finally, we present examples of FMO-catalyzed synthesis of natural products. Based on these explanations, this review will expand our knowledge of FMOs as powerful enzymes, as well as implementation of the FMOs as effective tools for biosynthesis

mechanismofdichloromethanedisproportionationovermesoporoustio2underlowtemperature

Mesoporous TiO2 was synthesized via nonhydrolytic template-mediated sol-gel route.Catalytic degradation performance upon dichloromethane over as-prepared mesoporous TiO2,pure anatase and rutile were investigated respectively.Disproportionation took place over as-made mesoporous TiO2 and pure anatase under the presence of water.The mechanism of disproportionation was studied by in situ FTIR.The interaction between chloromethoxy species and bridge coordinated methylenes was the key step of disproportionation.Formate species and methoxy groups would be formed and further turned into carbon monoxide and methyl chloride.Anatase(001)played an important role for disproportionation in that water could be dissociated into surface hydroxyl groups on such structure.As a result,the consumed hydroxyl groups would be replenished.In addition,there was another competitive oxidation route governed by free hydroxyl radicals.In this route,chloromethoxy groups would be oxidized into formate species by hydroxyl radicals transfering from the surface of TiO2.The latter route would be more favorable at higher temperature