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1.
Sci Total Environ ; 698: 134320, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31518779

RESUMO

Soil acidification is a major environmental issue associated with intensive agricultural land use. Rapid urbanization has inevitably caused great changes in agricultural land use around urban areas. However, the effects of agricultural land-use change and soil parent material on the pH dynamics of the whole soil profile remain poorly understood. Based on a paired soil resampling campaign in the 1980s and 2010s, this study evaluated the effects of agricultural land-use change and parent materials on the pH dynamics of the soil profile across the Chengdu Plain of China. The results showed that soil pH significantly decreased by 1.20, 0.72, 0.66 and 0.68 units at the 0-20, 20-40, 40-60 and 60-100 cm soil depths, respectively. Conversions of traditional rice-wheat/rapeseed rotations to rice-vegetable rotations and afforested land significantly increased the magnitude of pH decline at the 0-60 cm soil depth. Soils formed from Q4 grey-brown alluvium and Q4 grey alluvium, which had a lower soil bulk density (BD) and higher sand content, showed a much higher magnitude of pH decline than soils formed from Q3 (Quaternary Pleistocene) old alluvium, and significant acidification of deep soils only occurred in soils formed from Q4 (Quaternary Holocene) grey-brown alluvium and Q4 grey alluvium. These results suggested that agricultural land-use change aggravated acidification in the soil profile and the soil acidification degrees were parent material-dependent; in particular, significant acidification of deep soils was more inclined to occur in soils with lower soil BD and higher sand content due to their effects on the downward movement of acids and the penetration resistance of plant roots. More attention should be given to minimizing or preventing acidification of both topsoil and deep soils aggravated by agricultural land-use change across urban agricultural areas.

2.
Molecules ; 24(9)2019 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-31067724

RESUMO

One of the most challenging issues in photocatalytic hydrogen evolution is to efficiently separate photocharge carriers. Although MoS2 loading could effectively improve the photoactivity of TiO2, a fundamental understanding of the charge transfer process between TiO2 and MoS2 is still lacking. Herein, TiO2 photocatalysts with different exposed facets were used to construct MoS2/TiO2 heterostructures. XPS, ESR, together with PL measurements evidenced the Type II electron transfer from MoS2 to {001}-TiO2. Differently, electron-rich characteristic of {101}-faceted TiO2 were beneficial for the direct Z-scheme recombination of electrons in TiO2 with holes in MoS2. This synergetic effect between facet engineering and oxygen vacancies resulted in more than one order of magnitude enhanced hydrogen evolution rate. This finding revealed the elevating mechanism of constructing high-performance MoS2/TiO2 heterojunction based on facet and defect engineering.


Assuntos
Dissulfetos/química , Transporte de Elétrons , Hidrogênio/química , Molibdênio/química , Titânio/química , Catálise , Oxigênio/química , Processos Fotoquímicos
3.
Langmuir ; 35(8): 2909-2916, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30703328

RESUMO

One of the major challenges associated with fuel cells is exploring highly efficient and low-cost electrocatalysts for the oxygen reduction reaction (ORR). Herein, the feasibility of using Ti3C2 MXene nanoparticles (NPs) to enhance the electrocatalytic activity of g-C3N4 for ORR was investigated. By varying the content of Ti3C2 NPs, a series of g-C3N4/Ti3C2 heterostructures were obtained, displaying enhanced electrocatalytic activity, including a positive shift in both onset and peak potentials toward ORR, compared to the original g-C3N4 in basic solution. We attribute the improvement to the favorable electrical conductivity of well-dispersed Ti3C2 MXene nanoparticles and also enhanced O2 adsorption due to the electronic coupling effect between g-C3N4 and Ti3C2 in the heterostructures. This work demonstrates the potential of earth-abundant MXene family materials to construct low-cost and high-performance electrocatalysts.

4.
ACS Appl Mater Interfaces ; 10(40): 34068-34076, 2018 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-30220195

RESUMO

Porous nanostructures with a yolk-shell complex interior will provide lots of virtues to construct advanced catalysts. In our work, the preparation of novel yolk-shell Au nanocrystal-loaded Co3O4 nanocages (Co3O4/Au heterostructure) from a metal-organic framework-derived composite was reported. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and so forth were used to analyze the morphology, structure, and composition of the heterostructures. Most importantly, Co3O4/Au heterostructures are a kind of low-cost, good performance catalysts for the oxygen reduction reaction to replace the noble-Pt catalysts. The high surface area of the porous structure and the excellent electron transfer properties of well-dispersed Au nanocrystals and also the electronic coupling effect between Co3O4 and Au in the composites are attributed to the good performance.

5.
Phys Chem Chem Phys ; 20(16): 11405-11411, 2018 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-29645039

RESUMO

Co-catalyst loading provides an effective way to enhance the efficiency of photocatalysts for solar hydrogen production. From a sustainability point of view, it has immense scientific and technological values to explore more efficient co-catalytic systems by using multi-cocatalysts, because of potential synergetic effects between different components. Herein, the feasibility of using Ti3C2 MXene nanoparticles and Pt nanoclusters as dual co-catalysts to enhance the photoactivity of g-C3N4 for H2 production was investigated. Due to the improved electrical conductivity and increased reactive sites for photoreduction reactions, Ti3C2 and Pt co-modified photocatalysts exhibited a high photocatalytic hydrogen production activity of 5.1 mmol h-1 g-1. Compared to g-C3N4/Ti3C2 and g-C3N4/Pt, the 3- and 5-fold increased photoactivity demonstrated great potential of Ti3C2 MXene nanoparticles to construct high-performance photocatalysts. The synergetic effects between Ti3C2 and Pt were fundamentally investigated, indicating that the specific transfer of electrons not only contributed to the inhibited recombination of charge carriers but also resulted in good stability of heterostructured photocatalysts. Our results have demonstrated an approach worthy for the design and fabrication of high-efficiency heterostructures with superior photoactivity for hydrogen energy production.

6.
Nanotechnology ; 29(10): 105401, 2018 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-29319000

RESUMO

The electrochemical oxygen reduction reaction (ORR) has received great attention due to its importance in fuel cells and metal-air batteries. Here, we present a simple approach to prepare non-noble metal catalyst-Co3O4 nanocrystals (NCs). The particle size and shape were simply controlled by different types and concentrations of metal precursor. Furthermore, different sizes and shapes of Co3O4 NCs are explored as electrocatalysts for ORR, and it has been observed that particles with a similar shape, and smaller particle size led to greater catalytic current densities because of the greater surface area. For particles with a comparable size, the shape or crystalline structure governed the activity of the electrocatalytic reactions. Most importantly, the 9 nm-Co3O4 were demonstrated to act as low-cost catalysts for the ORR with a similar performance to that of Pt catalysts.

7.
Sci Rep ; 7(1): 12296, 2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-28947830

RESUMO

Photocatalysis is a promising strategy to address the global environmental and energy challenges. However, the studies on the application of the photocatalytically degraded dye-polluted water and the multi-purpose use of one type of catalyst have remained sparse. In this report, we try to demonstrate a concept of multiple and cyclic application of materials and resources in environmentally relevant catalyst reactions. A magnetic composite catalyst prepared from exfoliated titania nanosheets, graphene, the magnetic iron oxide nanoparticles, and a polyelectrolyte enabled such a cyclic application. The composite catalyst decomposed a methylene blue-polluted water under visible light, and then the catalyst was collected and removed from the treated water using a magnet. The photocatalytically treated water was then used to prepare the electrolyte in electrochemical reductive reactions and presented superior electrochemical performance compared with the dye-polluted water. The composite catalyst was once again used as the cathode catalyst in the electrochemical reaction. Each component in the composite catalyst was indispensable in its catalytic activity, but each component played different roles in the photochemical, magnetic recycling, and electrochemical processes. We expect the report inspire the study on the multi-functional catalyst and cyclic use of the catalytically cleaned water, which should contribute for the environmental and energy remedy from a novel perspective.

8.
Bioprocess Biosyst Eng ; 40(7): 1101-1110, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28439671

RESUMO

In this study, four fusion proteins were designed, in which the N-terminal cellulose-binding module as the affinity tag was immobilized on the regenerated amorphous cellulose (RAC), and the release of the C-terminal colored proteins was detected easily and rapidly after on-resin cleavage using the free tobacco etch virus protease (TEVp) variant, or the immobilized cognate protease with a binding capacity of up to 220 mg protein per gram of RAC. The enhanced stability and repetitive use of the immobilized TEVp compensated slight loss of the catalytic efficiency toward the soluble protein substrate. On-resin cleavage and purity of the released target proteins are related to the context of the fusion tag, the incorporated linker composition, and the colored protein. Owing to low cost and high binding capacity of the RAC, the TEVp immobilized on the resin is an ideal alternative for removing fusion tag. The colored proteins are easily monitored in the on-resin process of fusion proteins, and rapid separation from RAC.


Assuntos
Endopeptidases/metabolismo , Potyvirus/enzimologia , Celulose , Ligação Proteica , Proteínas Recombinantes de Fusão
9.
Analyst ; 142(5): 780-786, 2017 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-28134946

RESUMO

In this study, highly monodispersed Cu2SnZnS4 NCs with a quasi-spherical structure were prepared to construct a sandwich-type electrochemical immunosensor for alpha-fetoprotein detection. Quaternary Cu2SnZnS4 NCs as novel biomimetic catalysts show an efficient intrinsic peroxidase-like activity for H2O2 reduction. This excellent catalytic activity is ascribed to the higher electroconductivity than those of the binary Cu2S and ternary Cu2SnS3 NCs. Moreover, ß-cyclodextrin-functionalized graphene sheets are used as substrate materials that can capture large amounts of primary antibodies due to host-guest interaction and high surface area. Under the optimized conditions, the electrochemical immunosensor exhibites a wide working range from 0.5 pg mL-1 to 10 ng mL-1 and a detection limit of 0.16 pg mL-1 at a signal-to-noise ratio of 3. Good sensitivity, reproducibility, and stability demonstrate its potential application in clinical diagnostics.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Grafite , Imunoensaio , Nanopartículas Metálicas , Anticorpos/química , Cobre , Peróxido de Hidrogênio , Limite de Detecção , Reprodutibilidade dos Testes
10.
Appl Biochem Biotechnol ; 182(2): 769-781, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27988855

RESUMO

In this study, five fusion tags affecting soluble production and cleavage activity of the tobacco etch virus (TEV) protease (TEVp) variant in Escherichia coli strains BL21 (DE3) and Rosetta™ (DE3) are investigated. Combination of the augmenting rare transfer RNAs (tRNAs) and the fused expressivity tag (N-terminal seven amino acid residues of E. coli translation initiation factor II) promotes the soluble TEVp partner expressed at relatively high level. Attachment of the maltose-binding protein (MBP) tag increases soluble expression of the protease released from the fusion protein in E. coli cells, but the incorporated TEVp recognition sequence slightly decreases expressivity of the fusion construct. Except for the green fluorescent protein, the attached expressivity tag shows less efficiency than the MBP tag in enhancing expression levels of the selected five target proteins in the Rosetta™ (DE3) cells under different induction conditions. Our results identified that high-level production of the functional target protein as the fusion partner in E. coli is combined with the intrinsic property of fusion tag, fusion protein stability, inherent folding of target protein, rare tRNA abundance, and the incorporated linker. Purified TEVp fusion constructs with the N-terminal expressivity tag, as well as the MBP partner, are the ideal alternatives for removing fusion tag.


Assuntos
Endopeptidases , Escherichia coli , Proteínas Ligantes de Maltose , Proteínas Recombinantes de Fusão , Endopeptidases/biossíntese , Endopeptidases/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Ligantes de Maltose/biossíntese , Proteínas Ligantes de Maltose/genética , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Solubilidade
11.
Langmuir ; 32(44): 11639-11645, 2016 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-27756126

RESUMO

In this article, novel types of Bi2S3-Au heterostructures are fabricated through rationally controlling the growth atmosphere. Under argon, Au nanoparticles are preferentially deposited onto the tips of Bi2S3 nanorods to form Bi2S3-Au dumbbell heterostructures. In contrast, because of the etching effect by amine, Au nanoparticles are randomly anchored onto the surface of nanorods to form Bi2S3-Au nanocorns in the presence of oxygen. Furthermore, the size of gold nanoparticles can be controlled through adjusting the concentration of reaction precursors. Bi2S3-Au dumbbells show superior activity for the photodegradation of organic pollutants and an enhanced photoresponse compared to the Bi2S3-Au nanocorns. The significantly improved photocatalytic performance of Bi2S3-Au dumbbells is ascribed to the more efficient charge separation compared to that of Bi2S3-Au nanocorns. These heterostructures composed of environmentally friendly elements are expected to be promising for applications in the field of clean energy.

12.
PLoS One ; 11(8): e0161360, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27551716

RESUMO

Measles virus (MeV) is a highly contagious virus that still causes annual epidemics in developing countries despite the availability of a safe and effective vaccine. Additionally, importation from endemic countries causes frequent outbreaks in countries where it has been eliminated. The M protein of MeV plays a key role in virus assembly and cytopathogenesis; interestingly, M is localised in nucleus, cytoplasm and membranes of infected cells. We have used transient expression of M in transfected cells and in-cell transcription assays to show that only some MeV M localizes to the nucleus, in addition to cell membranes and the cytoplasm as previously described, and can inhibit cellular transcription via binding to nuclear factors. Additionally, MeV M was able to inhibit in vitro transcription in a dose-dependent manner. Importantly, a proportion of M is also localized to nucleus of MeV infected cells at early times in infection, correlating with inhibition of cellular transcription. Our data show, for the first time, that MeV M may play a role early in infection by inhibiting host cell transcription.


Assuntos
Glicoproteínas/genética , Vírus do Sarampo/genética , Sarampo/genética , Transcrição Genética , Membrana Celular/genética , Membrana Celular/virologia , Núcleo Celular/genética , Cromatina/genética , Cromatina/metabolismo , Glicoproteínas/metabolismo , Interações Hospedeiro-Patógeno/genética , Humanos , Sarampo/virologia , Vírus do Sarampo/patogenicidade , Ligação Proteica , Fatores de Transcrição/genética , Proteínas da Matriz Viral/genética , Proteínas da Matriz Viral/metabolismo , Montagem de Vírus/genética
13.
Phys Chem Chem Phys ; 18(24): 16208-15, 2016 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-27251953

RESUMO

Moderate efficiency and the utilization of noble metal cocatalysts are the key factors that restrict the large-scale application of photocatalytic hydrogen production. To develop more efficient photocatalysts based on earth abundant elements, either a new material strategy or a fundamental understanding of the semiconductor/cocatalyst interfaces is highly desirable. In this paper, we studied the feasibility of in situ formation of defect-rich cocatalysts on graphene-based photocatalysts. A facile biomolecule-assisted strategy was used to self-assmble Cd1-xZnxS/MoS2/graphene hollow spheres. The defect-mediated cocatalyst and synergetic charge transfer around heterostructured interfaces exhibit a significant impact on the visible-light-driven photocatalytic activity of multicomponent solid solutions. With engineered interfacial defects, Cd0.8Zn0.2S/MoS2/graphene hollow spheres exhibited a 63-fold improved H2 production rate, which was even 2 and 3.8 times higher than those of CdS/MoS2/graphene hollow spheres and Cd0.8Zn0.2S/Pt. Therefore, our research provides a promising approach for the rational design of high-efficiency and low-cost photocatalysts for solar fuel production.

14.
Langmuir ; 31(38): 10555-61, 2015 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-26343896

RESUMO

A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)-Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS-Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p-n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron-hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.

15.
Methods Mol Biol ; 1221: 11-24, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25261303

RESUMO

Human rhinoviruses (HRVs) are positive-stranded RNA viruses belonging to the Enterovirus genus in the family of Picornaviridae. Identification of the specific strain in HRV disease has been difficult because the traditional serological method is insensitive, labor intensive, and cumbersome. With the fast progress in molecular biological technique, more sensitive and faster molecular methods have been developed, such as polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, and real-time RT-PCR. To improve the technique for defining the links between illnesses and specific strains of HRV, we developed RT-PCR specific for HRV as routine base. A multiplex RT-PCR that simultaneously identifies 12 respiratory viruses including HRV is also routinely used in our lab. Here we have described the specific steps of methods for identification of HRV from clinical samples, such as sample preparation, isolation of total RNA, nested-RT-PCR for HRV, Seeplex(®) RV15 ACE Detection method, gel electrophoresis, how to use the QIAxcel(®) capillary electrophoresis system, and results interpretation.


Assuntos
Infecções por Picornaviridae/diagnóstico , Infecções por Picornaviridae/virologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Rhinovirus/patogenicidade , Resfriado Comum/virologia , Eletroforese em Gel de Ágar , Humanos , Reação em Cadeia da Polimerase/métodos , Infecções Respiratórias/virologia , Rhinovirus/genética
16.
Phys Chem Chem Phys ; 16(47): 26016-23, 2014 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-25358848

RESUMO

rGO-CdS-H2W12 nanocomposite film was successfully fabricated by a layer-by-layer self-assembly method. The composite film was characterized by techniques such as UV-Vis spectra, XPS, and AFM. The composite film showed high photoelectronic response under the illumination of sunlight. Both current-voltage curves and photocurrent transient measurements demonstrated that the photocurrent response of the rGO-CdS-H2W12 composite film was enhanced five-fold compared with CdS film. This can be attributed to the photoinduced electron transfer between CdS, H2W12 and rGO, which promotes the charge separation efficiency of CdS. The introduction of GO enhanced the charge separation and transportation. More importantly, various pollutants can be treated as electron donors, and can thus be degraded and produce hydrogen at the same time, at a low bias voltage under the irradiation of solar light.

17.
Nanoscale ; 6(19): 11336-43, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25141067

RESUMO

Fuel cells and metal-air batteries will only become widely available in everyday life when the expensive platinum-based electrocatalysts used for the oxygen reduction reactions are replaced by other efficient, low-cost and stable catalysts. We report here the use of nitrogen-doped graphdiyne as a metal-free electrode with a comparable electrocatalytic activity to commercial Pt/C catalysts for the oxygen reduction reaction in alkaline fuel cells. Nitrogen-doped graphdiyne has a better stability and increased tolerance to the cross-over effect than conventional Pt/C catalysts.

18.
Emerg Infect Dis ; 20(8): 1362-5, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25061975

RESUMO

During the early stage of the avian influenza A(H7N9) epidemic in China in March 2013, a strain of the virus was identified in a 4-year-old boy with mild influenza symptoms. Phylogenetic analysis indicated that this strain, which has similarity to avian subtype H9N2 viruses, may represent a precursor of more-evolved H7N9 subtypes co-circulating among humans.


Assuntos
Subtipo H7N9 do Vírus da Influenza A/genética , Influenza Humana/epidemiologia , Influenza Humana/virologia , Sequência de Aminoácidos , Pré-Escolar , China/epidemiologia , Genoma Viral , Genótipo , Humanos , Subtipo H7N9 do Vírus da Influenza A/classificação , Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Masculino , Dados de Sequência Molecular , Neuraminidase/genética , Filogenia , Alinhamento de Sequência , Proteínas Virais/genética
19.
J Am Chem Soc ; 136(26): 9236-9, 2014 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-24946131

RESUMO

Cu2ZnSnS4, based on abundant and environmental friendly elements and with a direct band gap of 1.5 eV, is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis. We detail here the synthesis of quasi-spherical Cu2ZnSnS4 nanoparticles with unprecedented narrow size distributions. We further detail their use as seeds to produce CZTS-Au and CZTS-Pt heterostructured nanoparticles. Such heterostructured nanoparticles are shown to have excellent photocatalytic properties toward degradation of Rhodamine B and hydrogen generation by water splitting.

20.
Emerg Infect Dis ; 20(5): 850-3, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24751370

RESUMO

In spring 2013, influenza A(H7N9) virus was isolated from an apparently healthy tree sparrow in Chongming Dongping National Forest Park, Shanghai City, China. The entire gene constellation of the virus is similar to that of isolates from humans, highlighting the need to monitor influenza A(H7N9) viruses in different species.


Assuntos
Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Pardais/virologia , Animais , China/epidemiologia , Genoma Viral , Geografia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Subtipo H7N9 do Vírus da Influenza A/classificação , Subtipo H7N9 do Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Dados de Sequência Molecular , Neuraminidase/genética , Filogenia , Proteínas Virais/genética
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