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1.
Sci Rep ; 9(1): 18734, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31822737

RESUMO

A novel cerium doped compounds Mn3Gd7-xCex(SiO4)6O1.5 with an apatite structure was found and used to achieve high-efficiency degradation of tetracycline in aqueous solution. The catalysts were characterized by XRD, XPS, EDS and other techniques. The characteristic results indicated that the catalytic activity of the compound was improved due to the introduction of Ce in the structure, because Ce3+ which was stably present in the apatite structure can serve as an active site for the reaction, and in addition, there was a high presence between Ce4+ and Ce3+ on the surface of the catalyst. The redox potential and high oxygen storage capacity were also beneficial for the catalytic reaction. The results of free radical capture indicated that both superoxide radicals and hydroxyl radicals participated in the catalytic oxidation process and played an important role in the reaction. The decomposition of tetracycline followed the pseudo second-order reaction kinetics. In addition, the catalyst exhibited long-term stability and low metal leaching during the reaction, which indicated that the novel cerium-doped apatite structure material could be a promising wastewater treatment material.

2.
Sci Rep ; 9(1): 15509, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31664113

RESUMO

What ideal w-LED phosphors always aim to do is to achieve a single phase near-sunlight emission phosphor simultaneously with both high luminescence efficiency and high thermal stability at operation temperature. And It is well known that apatite compound phosphors are one of the most promising optical materials to realize those above because of their unique structure enhanced luminescence properties and thermal stability. Here, we synthesized a co-doped single phase apatite phosphors Ca2La8(SiO4)6O2:Dy3+/Sm3+ (CLSO:Dy3+/Sm3+) for white light emission, which was provided with excellent thermal stability and of which luminescence intensity at 150 °C still was 92 percentage of that at room temperature. Moreover, X-ray diffraction technique, Fourier transform infrared spectroscopy, scanning electron microscope were employed to characterization of phase structure and morphology, and consequently pure apatite structure and gravel-like morphology of phosphors were proved. Analysis of photoluminescence spectra indicated that concentration quenching effect exist in single-doped CLSO:Dy3+ phosphors owing to dipole-dipole interaction between Dy3+ ions. It is revealed that maybe exist Dy3+ ↔ Sm3+ bilateral non-radiative energy transfer processes in Dy3+/Sm3+ co-doped CLSO system by PL spectra and decay curves. And variation of Sm3+ ion concentration can control color emission, namely CIE chromaticity coordinates and correlated color temperature, finally to achieve white light emission (0.309,0.309) with CCT 6848 K, able to be a potential candidate for commercial lighting applications.

3.
Front Chem ; 7: 437, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31259169

RESUMO

Although the electrochemical properties of porous LiMn2O4 microspheres are usually improved compared to those of irregular LiMn2O4 particles, the effects of the different synthesis conditions on the preparation of the porous LiMn2O4 microspheres are rarely discussed in detail. In the present work, porous LiMn2O4 microspheres were successfully synthesized by using molten LiOH and porous Mn2O3 spheres as a template. Multiple factors were considered in the preparation process, including reagent concentration, pH, adding mode, heating time, etc. The morphology of the MnCO3 template was crucial for the preparation of porous LiMn2O4 microspheres and it was mainly affected by the concentration of reactants and the pH value of the solution during the precipitation process. During the lithiation of Mn2O3 microspheres, the heating temperature and the ratio between Mn2O3 and lithium salt were the most significant variables in terms of control over the morphology and purity of the LiMn2O4 microspheres. Furthermore, we demonstrated that the porous LiMn2O4 microspheres presented better rate capability and cyclability compared to commercial LiMn2O4 powder as cathode materials for lithium-ion batteries (LIBs). This study not only highlights the shape-controllable synthesis of LiMn2O4 microspheres as promising cathode materials, but also provides some useful guidance for the synthesis of porous LiMn2O4 microspheres and other LIB' electrode materials.

4.
Materials (Basel) ; 12(2)2019 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-30669374

RESUMO

Gellable composite materials (GCM) were prepared from a smelting slag of copper and nickel deposits and cement, and activated using gypsum and chemical activators. The effects of material ratio, dosage of chemical activators, and gypsum on the mechanical properties of GCM were studied. Our results showed that the chemical activators of Na2SO4, Na2SiO3, NaOH, and Na2CO3 could improve the compressive strength of the GCM. Considering the market cost and ease operation, the compressive strength of the GCM could be significantly improved with 2% Na2SO4. The experiment results also showed that the compound chemical activator could improve the compressive strength of gelled material. The strength of GCM reaches 41.6 MPa when 2% gypsum and 80% of smelting slags of copper and nickel deposits were used, which met the national standards requirements of GCM. As such, it is expected that a large amount of copper and nickel mining smelting slag could be utilized for the production of cementitious materials.

5.
Front Chem ; 6: 558, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30515377

RESUMO

The Rietveld analysis of X-ray powder diffraction patterns is used widely for obtaining the structural information of clay minerals. However, the complex hydration behavior and the variability of interlayer contents are often considered difficult to be described correctly by a simple structure model. In the present work, the use of Cu-triethylenetetramine (Cu-trien)-exchanged nontronites has been proposed to simplify the interlayer structure. This method provides a potential to obtain the structural information of nontronites, for example, the layer charge density, occupancies of cis-octahedral sites, and the iron content by the Rietveld analysis from the X-ray powder diffraction patterns. The approach was demonstrated on three Cu-trien-exchanged nontronite samples. The Rietveld refinements were carried out first on the purified samples and the results showed a good peak fitting between measured and calculated patterns. The refined iron content and the occupancies of cis-octahedral sites are in general agreement with the reference data, which have been obtained from chemical and thermal analyses. The refinement of layer charge density showed lower values compared with the reference. It may be due to the assumption of temperature factor of Cu-trien in the interlayer. A raw sample with natural impurities was chosen to test the applicability of this method. The refinement pattern of the raw sample led to good agreement with the observed data. The results of the iron content and the occupancies of cis-octahedral sites showed the same tendency as purified samples. This study showed that this approach allows for obtaining some structural details of nontronites directly from X-ray powder diffraction patterns of Cu-trien-exchanged samples.

6.
Materials (Basel) ; 11(11)2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30405090

RESUMO

Nano zero-valent iron has drawn great attention for the degradation of organic dyes due to its high reactivity, large specific surface area, lightweight, and magnetism. However, the aggregation and passivation of iron nanoparticles may prohibit the wide use of it. A new composite material was prepared by loading nano zero-valent iron (nZVI) on montmorillonite (MMT) to overcome the above shortcomings and it was further used for the removal of Rhodamine 6G (Rh 6G) under microwave treatment in the present work. The effects of various parameters, including the initial concentration of Rh 6G, microwave power, and pH value were investigated. The new composite material (nZVI/MMT) showed an excellent degradation ability for removing Rh 6G, and the removal amount reached 500 mg/g within 15 min. The degradation rate reached 0.4365 min-1, significantly higher than most previous reports using other removal methods for Rh 6G.

7.
Front Chem ; 6: 463, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30356813

RESUMO

Nanoscale zero valent iron has been a widespread concern in various fields due to its large specific surface area and high reactivity. However, nanoscale zero valent iron (nZVI) is very likely to aggregate and be oxidized, which limit its wide application in industry. Most clay minerals have a large adsorption capacity of cations due to their negative charges and high specific surface areas. In the present work, nZVI was loaded onto two typical clay minerals: kaolinite and sepiolite, to inhibit its oxidation and aggregation. The composites were applied to degrade Rhodamine 6G (Rh 6G) under microwave irradiation. The effects of pH value and microwave power on degradation were studied. The results showed that the removal amount of Rh 6G by nZVI/kaolinite was 110 mg/g in 15 min, while it reached 300 mg/g by nZVI/sepiolite. The difference between these two composites was mostly determined by the structures of these two clay minerals.

8.
Front Chem ; 6: 367, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30186831

RESUMO

Hexavalent chromium species, Cr(VI), which can activate teratogenic processes, disturb DNA synthesis and induce mutagenic changes resulting in malignant tumors. The detection and quantification of Cr(VI) is very necessary. One of the rapid and simple methods for contaminant analysis is fluorescence detection using organic dye molecules. Its application is limited owing to concentration quenching due to aggregation of fluorescent molecules. In this study, we successfully intercalated 7-amino-4-methylcoumarin (AMC) into the interlayer space of montmorillonite (MMT), significantly inhibited fluorescence quenching. Due to enhanced fluorescence property, the composite was fabricated into a film with chitosan to detect Cr(VI) in water. Cr(VI) can be detected in aqueous solution by instruments excellent, ranging from 0.005 to 100 mM with a detection limit of 5 µM.

9.
Plasmid ; 98: 52-55, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-30201136

RESUMO

RNA interference (RNAi), based on hairpin RNA (hpRNA) expression, plays an important role in functional analysis of plant genes. Traditional methods for making RNAi constructs usually involve multiple time-consuming cloning steps. We have developed a Gateway-compatible binary vector for RNAi-mediated gene knockdown in plants from pCAMBIA2301 and pHANNIBAL vectors. The new plant RNAi binary vector, named pCAMBIA2301-GW-RNAi, has two inverted repeated Gateway cassettes driven by the cauliflower mosaic virus 35S (CaMV 35S) promoter. This enables site-specific recombination at two sites by one Gateway LR reaction without restriction enzymes and ligases. The pCAMBIA2301-GW-RNAi vector's effectiveness was evaluated by Agrobacterium-mediated transient co-expression assays of overexpression and silencing constructs of HvCEBiP in Nicotiana benthamiana followed by western blot analysis. Obtained results show that the developed RNAi vector successfully knocked down 35S-driven expression of HvCEBiP, as expression levels of the encoded HvCEBiP protein were significantly reduced.


Assuntos
Agrobacterium/genética , Técnicas de Silenciamento de Genes/métodos , Genes de Plantas , Vetores Genéticos , Plasmídeos/genética , Interferência de RNA , Tabaco/genética , Tabaco/microbiologia
10.
ACS Appl Mater Interfaces ; 10(35): 29467-29475, 2018 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-30091894

RESUMO

Microwave-induced catalytic degradation is considered amongst the most efficient techniques to remove antibiotic such as chlortetracycline from contaminated water. Described here is a new microwave-induced oxidation catalyst based on carbon nanotubes (CNTs) decorated uniformly with nanoparticles of Fe3O4. The combination of dielectric loss and magnetic loss of the material contributed to its stronger microwave absorption and the ability to produce more "hot spots". These hot spots promoted the oxidation of common antibiotics such as chlortetracycline, tetracycline, and oxytetracycline under microwave irradiation. Experiments with the addition of scavenger showed that hydroxy radicals (•OH) together with superoxide radicals (•O2-) contributed to the antibiotics removal as well. The final degradation products included CO2 and NO3- as confirmed by mass spectroscopy and ion chromatography analyses. The results indicated that the Fe3O4/CNTs was an efficient catalyst for microwave-induced oxidation.


Assuntos
Antibacterianos , Compostos Férricos/química , Nanopartículas Metálicas/química , Micro-Ondas , Nanotubos de Carbono , Antibacterianos/química , Catálise , Poluentes da Água/química , Purificação da Água
11.
Biotechniques ; 64(5): 219-224, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29673256

RESUMO

Yeast two-hybrid systems are powerful tools for analyzing interactions between proteins. Vector construction is an essential step in yeast two-hybrid experiments, which require bait and prey plasmids. In this study, we modified the multiple cloning site sequence of the yeast plasmid pGADT7 by site-directed mutagenesis PCR to generate the pGADT7-In vector, which resulted in an easy and rapid method for constructing yeast two-hybrid vectors using the In-Fusion cloning technique. This method has three key advantages: only one pair of primers and one round of PCR are needed to generate bait and prey plasmids for each gene, it is restriction endonuclease- and ligase-independent, and it is fast and easily performed.


Assuntos
Vetores Genéticos , Genética Reversa/métodos , Técnicas do Sistema de Duplo-Híbrido , Clonagem Molecular/métodos , Escherichia coli/genética , Mutagênese Sítio-Dirigida , Plasmídeos/genética , Reação em Cadeia da Polimerase , Leveduras/genética
12.
Front Chem ; 6: 16, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29556493

RESUMO

With a layered structure, layered double hydroxide (LDH) has potential applications in remediation of anionic contaminants, which has been a hot topic for recent years. In this study, a Cl type Mg-Al hydrotalcite (Cl-LDH) was prepared by a co-precipitation method. The adsorption process of three pharmaceuticals and personal care products (PPCPs) [tetracycline (TC), diclofenac sodium (DF), chloramphenicol (CAP)] by Cl-LDH was investigated by X-ray diffraction (XRD), Zeta potential, dynamic light scattering (DLS), BET, Fourier transform infrared (FTIR) spectroscopy, and molecular dynamics simulation. The results showed that the adsorption equilibrium of TC and DF could be reached in 120 min, and the maximum adsorption capacity of the TC and DF were 1.85 and 0.95 mmol/g, respectively. The isothermal adsorption model of TC was fitted with the Freundlich adsorption model, and the isothermal adsorption model of DF was fitted with the Langmuir adsorption model. The adsorption dynamics of TC and DF followed the pseudo-second-order model. The adsorption mechanisms of the three PPCPs into Cl-LDH were different based on the experimental results and molecular dynamics simulation. The TC adsorption on Cl-LDH was accompanied by the electrostatic interactions between the negative charge of TC and the positive charge of Cl-LDH. The uptake of DF was attributed to anion exchange and electrostatic interaction. Cl-LDH does not adsorb CAP due to no electrostatic interaction. The molecular dynamic simulation further confirmed different configurations of three selected PPCPs, which were ultimately responsible for the uptake of PPCPs on Cl-LDH.

13.
Front Chem ; 6: 624, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30619831

RESUMO

Thin and lightweight flexible lithium-ion batteries (LIBs) with high volumetric capacities are crucial for the development of flexible electronic devices. In the present work, we reported a paper-like ultrathin and flexible Si/carbon nanotube (CNT) composite anode for LIBs, which was realized by conformal electrodeposition of a thin layer of silicon on CNTs at ambient temperature. This method was quite simple and easy to scale up with low cost as compared to other deposition techniques, such as sputtering or CVD. The flexible Si/CNT composite exhibited high volumetric capacities in terms of the total volume of active material and current collector, surpassing the most previously reported Si-based flexible electrodes at various rates. In addition, the poor initial coulombic efficiency of the Si/CNT composites can be effectively improved by prelithiation treatment and a commercial red LED can be easily lighted by a full pouch cell using a Si/CNT composite as a flexible anode under flat or bent states. Therefore, the ultrathin and flexible Si/CNT composite is highly attractive as an anode material for flexible LIBs.

14.
Sci Rep ; 7(1): 15171, 2017 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-29123224

RESUMO

A novel red-emitting phosphor NaY9(SiO4)6O2:Sm3+ (NYS:Sm3+) was synthesized and the X-ray diffraction and high-resolution TEM testified that the NYS compound belongs to the apatite structure which crystallized in a hexagonal unit cell with space group P63/m. The novel phosphor boasts of such three advantageous properties as perfect compatible match with the commercial UV chips, 73.2% quantum efficiency and 90.9% thermal stability at 150 °C. Details are as follows. NYS:Sm3+ phosphor showed obvious absorption in the UV regions centered at 407 nm, which can be perfectly compatible with the commercial UV chips. The property investigations showed that NYS:Sm3+ phosphor emitted reddish emission with CIE coordination of (0.563, 0.417). The optimum quenching concentration of Sm3+ in NYS phosphor was about 10%mol, and the corresponding concentration quenching mechanism was verified to be the electric dipole-dipole interaction. Upon excitation at 407 nm, the composition-optimized NYS:0.10Sm3+ exhibited a high quantum efficiency of 73.2%, and its luminescence intensity at 150 °C decreased simply to 90.9% of the initial value at room temperature. All of the results indicated that NYS:Sm3+ is a promising candidate as a reddish-emitting UV convertible phosphor for application in white light emitting diodes (w-LEDs).

15.
Sci Rep ; 7(1): 13414, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-29042613

RESUMO

Divalent mercury ion (Hg2+) is one of the most common pollutants in water with high toxicity and significant bioaccumulation, for which sensitive and selective detection methods are highly necessary to carry out its detection and quantification. Fluorescence detection by organic dyes is a simple and rapid method in pollutant analyses and is limited because of quenching caused by aggregation dye molecules. Hydrotalcite (LDH) is one of the most excellent carrier materials. In this study, an organic dye acridine orange (AO) was successfully loaded on the LDH layers, which significantly inhibited fluorescence quenching of AO. The composite AO/LDH reaches the highest fluorescence intensity when the AO initial concentration is 5 mg/L. With its enhanced fluorescent property, the composite powder was fabricated to fluorescence test papers. The maximal fluorescence intensity was achieved with a pulp to AO/LDH ratio of 1:5 which can be used to detect Hg2+ in water by naked eyes. Hg2+ in aqueous solution can be detected by instruments in the range of 0.5 to 150 mM. The novelty of this study lies on both the development of a new type of mineral-dye composite material, as well as its practical applications for fast detection.

16.
J Hazard Mater ; 338: 428-436, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28595157

RESUMO

Manganese oxides exhibit an excellent microwave absorption performance that could increase the degradation efficiency of organic pollutants in contaminated water. Incorporation of various transition metals into manganese oxides could bring about changes in their crystal structure and improve their physicochemical performance. In this work, a better microwave absorption material was obtained by adjusting and controlling the electron spin magnetic moments of Fe-doped birnessite. The powder X-ray diffraction, inductive coupled plasma emission spectrometer, X-ray photoelectron spectroscopy, and network analyses were performed to characterize the crystal structure, chemical composition, valence and content of the elements, and the microwave absorption performance of the obtained samples. Doping Fe into birnessite resulted in little changes to their crystal structure. The narrow energy spectrum of Fe (2p) revealed that the doped Fe was in the form of Fe (III) in birnessite structure. As the content of Fe (III) increased, the content of Mn (III) decreased accordingly. Substitution of Mn (III) by Fe (III) in the birnessite crystal lattice, confirmed by combining the characterization analyses with structure refinements for each doped sample, increased the overall numbers of unpaired electrons in birnessite structure, resulting in a higher electron spin magnetic moment and better microwave response. Compared with the non-doped sample, Fe-doped birnessite improved the efficiency of tetracycline degradation, which proved that Fe-doped birnessite indeed had better response towards the microwave, and thus, could be utilized for better removal of organic pollutants under microwave irradiation.


Assuntos
Espectroscopia de Ressonância de Spin Eletrônica/métodos , Ferro/química , Micro-Ondas , Óxidos/química , Tetraciclina/química , Catálise , Cristalografia por Raios X , Estrutura Molecular , Oxirredução , Espectroscopia Fotoeletrônica , Difração de Pó
17.
Nanoscale Res Lett ; 12(1): 302, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28449547

RESUMO

In order to reduce the amount of inactive materials, such as binders and carbon additives in battery electrode, porous cobalt monoxide nanofibers were directly grown on conductive substrate as a binder/additive-free lithium-ion battery anode. This electrode exhibited very high specific discharging/charging capacities at various rates and good cycling stability. It was promising as high capacity anode materials for lithium-ion battery.

18.
Sci Rep ; 6: 37400, 2016 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-27853275

RESUMO

The frequencies of microwave absorption can be affected by the permanent electric dipole moment which could be adjusted by modifying the crystal symmetry of the microwave absorbing materials. Herein, we corroborate this strategy experimentally and computationally to the microwave absorption of manganese dioxides. Nanosized Co-doped cryptomelane (Co-Cryp) was successfully synthesized by a one-step reaction. The introduction of Co(III) induced a change of crystal symmetry from tetragonal to monlclinic, which could lead to an increase of its permanent electric dipole moment. As a result, the frequencies of maximum microwave absorption were regulated in the range of 7.4 to 13.9 GHz with a broadened bandwidths. The results suggested that microwave absorption of manganese dioxides can be tailored with Co doping to expand their potential uses for abatement of various microwave pollutions.

19.
J Colloid Interface Sci ; 479: 115-120, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27380016

RESUMO

Mn intercalated hydrotalcite was prepared using a reconstruction method. And Mn intercalation was confirmed by XRD, FTIR, and thermal analyses. The different valences of Mn were present as determined by XPS. Calcination slightly promoted the isomorphic replacement of Mn(2+) and Mn(3+) for Mg(2+) and Al(3+), especially the replacement of Mn(2+) for Mg(2+) and Al(3+), and to some extent, reduced Mn intercalation. Ultrasonic treatment significantly increased Mn intercalation in permanganate form (Mn(7+)), and promoted the replacement of Mn(2+) for Mg(2+) and Al(3+). XRF analysis showed that ultrasonic treatment decreased the unbalanced layer charge of Mn intercalated hydrotalcite, while prolonged calcination increased it. These results may provide guidance on the preparation and application of Mn intercalated hydrotalcite. Extended calcination time and ultrasonic vibration increased the interlayer spacing of hydrotalcite, as a result of reduction in layer charge. As the layer charge was not completely balanced after Mn intercalation, a certain amount of CO3(2-) was re-adsorbed into the interlayer space. Mn-hydrotalcites with different layer charges, different contents of Mn with varying valences are expected to have different performances in the process of adsorption, degradation, and catalysis.

20.
Phys Chem Chem Phys ; 18(23): 15545-54, 2016 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-27165439

RESUMO

The lutetium containing nitride apatite Lu5(SiO4)3N was prepared by a solid state reaction at high temperature for the first time. Rietveld refinement indicated that the Lu5(SiO4)3N compound has a hexagonal space group of P63/m with cell parameters a = b = 9.700 Å and c = 7.238 Å. Additionally, the results revealed that there are two distinct lutetium sites in the Lu5(SiO4)3N host lattice, i.e. a Lu(1) site with nine coordination (Wyckoff site 4f) and a Lu(2) site with seven coordination (Wyckoff site 6h). Furthermore, the ratio of the number of Lu atoms in Lu(1) and Lu(2) sites is 3 : 2. The band gap for Lu5(SiO4)3N was determined to be 4.12 eV based on the density functional theory (DFT). In the Ce(3+) doped Lu5(SiO4)3N:0.03Ce(3+) compound, the emission peak centered at 462 nm was observed with the Commission International de I'Eclairage (CIE) coordinates of (0.148, 0.184), indicating blue-emission. Remarkably, in Ce(3+) and Tb(3+) co-doped Lu4.97-y(SiO4)3N:0.03Ce(3+),yTb(3+) compounds, the color-tunability was observed with increasing Tb(3+) co-doping rate on moving from blue at Tb(3+) = 0.00 to green at Tb = 0.09, due to the energy transfer from Ce(3+) to Tb(3+) ions being matched well with the decay curve results. Under the excitation at 359 nm, the absolute quantum efficiency (QE) for Lu5(SiO4)3N:0.03Ce(3+) was determined to be 42.13%. This phosphor material could be a platform for modeling a new phosphor and application in the solid-state lighting field.

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