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1.
ACS Appl Mater Interfaces ; 13(33): 39066-39075, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34387079

RESUMO

A controlled release formulation based on silica microcapsules is an ideal selection to improve both the effective utilization and duration of pesticides to decrease ecological damage. Herein, a simple and green method for preparing double-shelled microcapsules was developed using a newly prepared quaternary ammonium ionic liquid (IL) as the functional additive to entrap avermectin (Ave) in mesoporous silica nanospheres (MSNs) and tannic acid-Cu (TA-Cu) complex as the sealing agent to form the core-shell structure (Ave-IL@MSN@TA-Cu). The obtained microcapsules with an average size of 538 nm had pH-responsive release property and good stability in soil. The half-life of microcapsules (34.66 days) was 3 times that of Ave emulsifiable concentrate (EC) (11.55 days) in a test soil, which illustrated that microcapsules could protect Ave from rapid degradation by microorganisms by releasing TA, copper, and quaternary ammonium in the soil. Ave-IL@MSN@TA-Cu microcapsules had better nematicidal activity and antibacterial activity than Ave EC due to the synergistic effect of Ave, IL, and copper incorporated in the microcapsules. Pot experiments showed that the control efficacy of microcapsules was 87.10% against Meloidogyne incognita, which is better than that of Ave EC (41.94%) at the concentration of 1.0 mg/plant by the root-irrigation method after 60 days of treatment owing to the extended duration of Ave in microcapsules. The simple and green method for the preparation of double-shelled microcapsules based on natural quaternary ammonium IL would have tremendous potential for the extensive development of controlled release pesticide formulations.


Assuntos
Cápsulas/química , Preparações de Ação Retardada/química , Controle de Pragas/métodos , Praguicidas/química , Dióxido de Silício/química , Tylenchoidea/efeitos dos fármacos , Animais , Complexos de Coordenação/química , Cobre/química , Preparações de Ação Retardada/farmacologia , Composição de Medicamentos , Liberação Controlada de Fármacos , Química Verde , Concentração de Íons de Hidrogênio , Líquidos Iônicos/química , Ivermectina/análogos & derivados , Ivermectina/química , Ivermectina/farmacologia , Praguicidas/farmacologia , Porosidade , Compostos de Amônio Quaternário/química , Solubilidade , Taninos/química , Fatores de Tempo
2.
Sci Total Environ ; 798: 149167, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34375261

RESUMO

Single biomass feedstock approach may not meet the requirements for developing biochar with desired characteristics for use as soil amendment. In this study, biochars were prepared by co-pyrolysis of nutrients-rich Enteromorpha prolifera and lignocellulose-rich corn straw (CPECs) at different mass ratios (3:7, 1:1, and 7:3). CPECs presented higher water-soluble N/P contents than corn straw biochar, and exhibited larger surface area, low Na content, and slower nutrient release rate than Enteromorpha prolifera biochar. The modification in physicochemical and properties of CPECs enhanced its potential application as a soil amendment. A pot experiment showed that CPECs derived from co-pyrolysis of appropriate ratios of Enteromorpha prolifera and corn straw (1:1, 7:3) significantly increased the biomass of cherry tomato plant by 64.05%, 40.03% and 81.88%, 55.25%, when compared with corn straw biochar and Enteromorpha prolifera biochar, respectively. The positive effects of CPECs were primarily attributed to improved soil properties (e.g., water holding capacity, soil organic matter, pH, soil nutrients content) and increased total N/P uptake by plants. The results of this work provided potentials of developing "designer" biochars to meet the multiple soil requirements by co-pyrolysis.


Assuntos
Solo , Zea mays , Carvão Vegetal , Pirólise
3.
Sci Total Environ ; 616-617: 427-434, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29127796

RESUMO

Climate warming is expected to increasingly influence boreal peatlands and alter their greenhouse gases emissions. However, the effects of warming on N2O fluxes and the N2O budgets were ignored in boreal peatlands. Therefore, in a boreal peatland of permafrost zone in Northeast China, a simulated warming experiment was conducted to investigate the effects of warming on N2O fluxes in Betula. Fruticosa community (B. Fruticosa) and Ledum. palustre community (L. palustre) during the growing seasons from 2013 to 2015. Results showed that warming treatment increased air temperature at 1.5m aboveground and soil temperature at 5cm depth by 0.6°C and 2°C, respectively. The average seasonal N2O fluxes ranged from 6.62 to 9.34µgm-2h-1 in the warming plot and ranged from 0.41 to 4.55µgm-2h-1 in the control plots. Warming treatment increased N2O fluxes by 147% and transformed the boreal peatlands from a N2O sink to a source. The primary driving factors for N2O fluxes were soil temperature and active layer depth, whereas soil moisture showed a weak correlation with N2O fluxes. The results indicated that warming promoted N2O fluxes by increasing soil temperature and active layer depth in a boreal peatland of permafrost zone in Northeast China. Moreover, elevated N2O fluxes persisted in this region will potentially drive a noncarbon feedback to ongoing climate change.

4.
Immunity ; 47(5): 903-912.e4, 2017 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-29126797

RESUMO

Alveolar macrophages (AMs) derive from fetal liver monocytes, which colonize the lung during embryonic development and give rise to fully mature AMs perinatally. AM differentiation requires granulocyte macrophage colony-stimulating factor (GM-CSF), but whether additional factors are involved in AM regulation is not known. Here we report that AMs, in contrast to most other tissue macrophages, were also dependent on transforming growth factor-ß receptor (TGF-ßR) signaling. Conditional deletion of TGF-ßR in mice at different time points halted the development and differentiation of AMs. In adult mice, TGF-ß was also critical for AM homeostasis. The source of TGF-ß was AMs themselves, indicative of an autocrine loop that promotes AM self-maintenance. Mechanistically, TGF-ßR signaling resulted in upregulation of PPAR-γ, a signature transcription factor essential for the development of AMs. These findings reveal an additional layer of complexity regarding the guidance cues, which govern the genesis, maturation, and survival of AMs.


Assuntos
Homeostase , Macrófagos Alveolares/fisiologia , Fator de Crescimento Transformador beta/fisiologia , Animais , Diferenciação Celular , Desenvolvimento Embrionário , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Fatores de Crescimento Transformadores beta/fisiologia , Transdução de Sinais/fisiologia , Transcriptoma
6.
Nat Immunol ; 17(12): 1397-1406, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27776109

RESUMO

Microglia are the resident macrophages of the central nervous system (CNS). Gene expression profiling has identified Sall1, which encodes a transcriptional regulator, as a microglial signature gene. We found that Sall1 was expressed by microglia but not by other members of the mononuclear phagocyte system or by other CNS-resident cells. Using Sall1 for microglia-specific gene targeting, we found that the cytokine receptor CSF1R was involved in the maintenance of adult microglia and that the receptor for the cytokine TGF-ß suppressed activation of microglia. We then used the microglia-specific expression of Sall1 to inducibly inactivate the murine Sall1 locus in vivo, which resulted in the conversion of microglia from resting tissue macrophages into inflammatory phagocytes, leading to altered neurogenesis and disturbed tissue homeostasis. Collectively, our results show that transcriptional regulation by Sall1 maintains microglial identity and physiological properties in the CNS and allows microglia-specific manipulation in vivo.


Assuntos
Microglia/fisiologia , Fagócitos/imunologia , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Fatores de Transcrição/metabolismo , Animais , Células Cultivadas , Perfilação da Expressão Gênica , Inativação Gênica , Homeostase/genética , Mediadores da Inflamação/metabolismo , Ativação de Macrófagos/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurogênese/genética , Fatores de Transcrição/genética , Transcriptoma , Fator de Crescimento Transformador beta/metabolismo
7.
PLoS One ; 11(8): e0160612, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27501148

RESUMO

Global management of wetlands to suppress greenhouse gas (GHG) emissions, facilitate carbon (C) sequestration, and reduce atmospheric CO2 concentrations while simultaneously promoting agricultural gains is paramount. However, studies that relate variability in CO2 and CH4 emissions at large spatial scales are limited. We investigated three-year emissions of soil CO2 and CH4 from the primary wetland types of the Liaohe Delta, China, by focusing on a total wetland area of 3287 km2. One percent is Suaeda salsa, 24% is Phragmites australis, and 75% is rice. While S. salsa wetlands are under somewhat natural tidal influence, P. australis and rice are managed hydrologically for paper and food, respectively. Total C emissions from CO2 and CH4 from these wetland soils were 2.9 Tg C/year, ranging from 2.5 to 3.3 Tg C/year depending on the year assessed. Primary emissions were from CO2 (~98%). Photosynthetic uptake of CO2 would mitigate most of the soil CO2 emissions, but CH4 emissions would persist. Overall, CH4 fluxes were high when soil temperatures were >18°C and pore water salinity <18 PSU. CH4 emissions from rice habitat alone in the Liaohe Delta represent 0.2% of CH4 carbon emissions globally from rice. With such a large area and interannual sensitivity in soil GHG fluxes, management practices in the Delta and similar wetlands around the world have the potential not only to influence local C budgeting, but also to influence global biogeochemical cycling.


Assuntos
Dióxido de Carbono/análise , Metano/análise , Solo/química , Áreas Alagadas , Carbono/análise , China , Monitoramento Ambiental/métodos , Estações do Ano
8.
J Am Chem Soc ; 132(13): 4876-86, 2010 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-20222662

RESUMO

Variable pressure and temperature conductivity measurements on the bisthiaselenazolyl radical dimer [1a](2) have established the presence of a weakly metallic state over the pressure range 5-9 GPa. To explore the origin of this metallization we have examined the crystal and molecular structure of [1a](2) as a function of pressure. At ambient pressure the dimer consists of two radicals linked by a hypervalent 4-center 6-electron S...Se-Se...S sigma-bond into an essentially coplanar arrangement. The dimers are packed in cross-braced slipped pi-stack arrays running along the x-direction of the monoclinic (space group P2(1)/c) unit cell. Pressurization to 4 GPa induces little change in the molecular structure of [1a](2) or in the slipped pi-stack crystal architecture. Near 5 GPa, however, stress on the dimer leads to buckling of the two halves of the molecule and a contraction in the metrics of the S...Se-Se...S unit. These structural changes can be understood in terms of an electronic configurational switch from a 4-center 6-electron sigma-bonded dimer to a more conventional pi-bonded arrangement. At the same time the slipped pi-stack arrays undergo a concertina-like compression, and the crystal structure experiences highly anisotropic changes in cell dimensions. DFT calculations on the molecular electronic structure of the dimer indicate a marked decrease in the HOMO-LUMO gap as the dimer buckles. Related solid-state calculations indicate a rapid closure of the valence/conduction band gap in the same pressure region and the formation of a quasi-metallic state. Metallization of [1a](2) thus arises as much from intramolecular changes, which give rise to a collapse of the HOMO-LUMO gap and near coalescence of the valence and conduction bands, as from increased intermolecular interactions, which cause widening and overlap of the band edges.


Assuntos
Compostos Organometálicos/química , Selênio/química , Simulação por Computador , Dimerização , Condutividade Elétrica , Radicais Livres/química , Modelos Químicos , Pressão , Compostos de Sulfidrila/química , Temperatura
9.
Inorg Chem ; 48(20): 9874-82, 2009 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-19764707

RESUMO

Reduction of the N-methylated bis-1,2,3-thiaselenazolylium salts [2a,b,c][OTf] (with R(1) = Me and R(2) = H (2a), F (2b), Me (2c)) affords the corresponding bis-1,2,3-thiaselenazolyl radicals 2a,b,c. The radicals crystallize as centrosymmetric Se-Se sigma-bonded dimers [2a,b,c](2), in which an intramolecular Se-S bond of the radical is cleaved and replaced by an intermolecular Se-Se bond. The crystal structures of the three dimers are isomorphous, all belonging to the monoclinic space group P2(1)/c, and consist of interpenetrating, cross-braced, slipped pi-stack arrays laced together by numerous short intermolecular Se-N' and Se-S' contacts. In the solid state the dimers are diamagnetic, and behave as small band gap semiconductors with a room temperature conductivity sigma(RT) near 10(-6) S cm(-1). Application of pressure leads to a dramatic increase in conductivity for all three compounds. At 5 GPa the value of sigma(RT) ranges from near 10(-1) S cm(-1) for [2c](2) to 1 S cm(-1) for [2b](2) and 10(1) S cm(-1) for [2a](2). Comparison of the three crystal structures suggests that the compressibility of [2a](2), and hence the response of its conductivity to pressure, is superior to that of [2b,c](2).

10.
J Am Chem Soc ; 131(20): 7112-25, 2009 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-19413327

RESUMO

The synthesis and solid-state characterization of the resonance-stabilized heterocyclic thia/selenazyl radicals 1a-4a is described. While all the radicals crystallize in undimerized slipped pi-stacked arrays, the four crystal structures do not constitute an isomorphous set; crystals of 1a and 3a belong to the orthorhombic space group P2(1)2(1)2(1), while those of 2a and 4a belong to the monoclinic space group P2(1)/n. The origin of the structural dichotomy can be traced back to the packing of the radicals in the P2(1)/n structure, which maximizes intermolecular Se-Se' contacts. There are marked differences in the transport properties of the two groups. Variable temperature conductivity measurements reveal high, but activated, conductivity for the monoclinic pair (2a/4a), with sigma(298 K) > 10(-3) S cm(-1). The application of physical pressure increases the conductivity of both compounds, with sigma(298 K) at 5 GPa reaching 0.5 S cm(-1) for 2a and 2 S cm(-1) for 4a. Variable-temperature magnetic susceptibility measurements indicate strong antiferromagnetic (AFM) coupling for the monoclinic pair 2a and 4a, the behavior of which has been modeled in terms of a molecular-field modified 1D Heisenberg chain of AFM coupled S = 1/2 centers. Extended Huckel theory band structure calculations and density functional theory first principles methods have been used to develop a qualitative understanding of the conductive and magnetic properties of radicals of the type 1-4 as a function of the degree and direction of slippage of the radical pi-stacks.

11.
J Am Chem Soc ; 129(25): 7903-14, 2007 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-17542584

RESUMO

A general synthetic route to the resonance-stabilized pyrazine-bridged bisdithiazolyl framework, involving the reductive deprotection of 2,6-diaminopyrazine-bisthiocyanate and cyclization with thionyl chloride, has been developed. An N-methyl bisdithiazolyl radical, 4-methyl-4H-bis[1,2,3]dithiazolo[4,5-b:5',4'-e]pyrazin-3-yl, has been prepared and characterized in solution by electron paramagnetic resonance spectroscopy and cyclic voltammetry. Its crystal structure has been determined at several temperatures. At 295 K, the structure belongs to the space group Cmca and consists of evenly spaced radicals pi-stacked in an alternating ABABAB fashion along the x-direction. At 123 K, the space group symmetry is lowered by loss of C-centering to Pccn, so that the radicals are no longer evenly spaced along the pi-stack. At 88 K, a further lowering of space group symmetry to P21/c is observed. Extended Hückel Theory band structure calculations indicate a progressive opening of a band gap at the Fermi level in the low-temperature structures. Magnetic susceptibility measurements over the range 4-300 K reveal essentially diamagnetic behavior below 120 K. Variable-temperature single-crystal conductivity (sigma) measurements indicate that the conductivity is activated, even at room temperature, with a room-temperature value sigma RT=0.001 S cm-1 and a thermal activation energy Eact=0.19 eV. Under an applied pressure of 5 GPa, sigma RT is increased by 3 orders of magnitude, but the conductivity remains activated, with Eact being lowered to 0.11 eV at 5.5 GPa.

12.
J Am Chem Soc ; 127(51): 18159-70, 2005 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-16366569

RESUMO

A synthetic sequence to salts of N-alkylated pyridine-bridged 1,2,3-thiaselenazolo-1,2,3-thiaselenazolylium cations [2]+ (R1 = Me, Et; R2 = H) is described. The corresponding radicals 2 (R1 = Me, Et; R2 = H) can be generated from the cations by chemical or electrochemical reduction. Crystals of the two radicals are isostructural and consist of interpenetrating pi-stacked arrays of closed-shell Se-Se sigma-bonded dimers [2]2 laced together with numerous short intermolecular Se- - -Se, Se- - -S, and Se- - -N contacts. Variable-temperature magnetic, conductivity, and near-infrared optical measurements indicate that the bulk materials behave as small band gap semiconductors with room-temperature conductivities sigma(RT) near 10(-6) S cm(-1) and thermal activation energies Ea of 0.32 eV (R1 = Me) and 0.36 eV (R1 = Et). LMTO band structure calculations on both compounds are consistent with this interpretation. The application of external pressure leads to dramatic increases in conductivity; at 4 GPa sigma(RT) reaches a value near 10(-1) S cm(-1) for R1 = Me and 10(-2) S/cm for R1 = Et. The conductivity remains activated for both compounds, but for R1 = Me the activation energy Ea is reduced to near 0.03 eV at 5 GPa, suggestive of a weakly metallic state.

13.
Chem Commun (Camb) ; (46): 5745-7, 2005 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-16307132

RESUMO

The first example of an undimerized pi-stacked bis-1,2,3-thiaselenazolyl radical displays improved bandwidth and conductivity relative to an isostructural bis-1,2,3-dithiazolyl.

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