摘要：
An amperometric immunosensor based on new thiolated bionanocomposite with a high dispersion of gold nanoparticles (AuNPs) for the sensitive detection of indole-3-acetic acid (IAA) is being reported herein. Briefly, a thiolated nanocomposite was prepared via the microwave-assisted thiol-ene reaction of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) with oxidized polyaniline (PANI), which was synthesized in the presence of multiwalled carbon nanotubes (MWCNTs), yielding thiolated polyaniline (TPANI)-MWCNTs. Further, AuNPs were deposited on the TPANI-MWCNTs by microwave-assisted method to obtain a AuNPs/TPANI-MWCNTs nanocomposite. Finally, the thiolated bionanocomposite film was constructed via the specific chemical reaction between boronic acid functionalized AuNPs and the vicinal diol functionalized AuNP labeled immunoglobulin G (IgG-AuNPs). The change in the reduction peak current of Fe(CN)(6)(3-) was used to monitor the immunoreaction between IAA and antibody. The TPANI-MWCNT nanocomposites uniformly disperse AuNPs, IgG-AuNPs and anti-IAA-AuNPs, leading to the amplification of the signal of the immunosensor. Fourier transform infrared spectra (FTIR), cyclic voltammetry (CV), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-vis) and differential pulse voltammetry (DPV) were used to characterize the nanocomposite film and the stepwise modification of the immunosensor. The prepared thiolated bionanocomposite material has good biocompatibility, a highly uniform dispersion of the AuNPs with a narrow size distribution as verified by TEM, and high load/activity of the immobilized antibody proved via DPV. The fabricated IAA amperometric immunosensor not only exhibits a good linear arrange from 1.0 pg mL(-1) to 10 ng mL(-1) with the limit of detection of 0.97 pg mL(-1) (S/N = 3), but also possesses good selectivity, reproducibility and stability for the detection of IAA.
摘要：
A molecular beacons (MBs) loaded on molybdenum disulfide (MoS2) nanosheets as fluorescence probes for sensitive and versatile detection of microRNAs (miRNAs) through hybridization chain reaction (HCR) has been designed. MoS2 was used as a adsorbent to capture the MBs and a selective fluorescence quencher to reduce the background signal. In the absence of miRNAs, HCR could not be triggered due to the stability of MB probes. The probes attached to the MoS2 surface, efficiently quenching fluorescence of the G-quadruplex/Thioflavin T. However, the presence of target miRNAs triggers the HCR process to generate large amount of HCR products. Meanwhile, the HCR products of long nanowires chain with abundant G-quadruplexes could not be adsorbed on the surface of MoS2, and therefore detach from the MoS2. Consequently, Thioflavin T could be embedded in G-quadruplexes and produced strong fluorescence signal. This fluorescence emission signal could achieve detection of miRNA as low as 4.2 pM and a wide linear ranges from 0.1 to 100nM. In addition, a versatile fluorescence probe has been developed for detection of miRNA-21 by changing the miRNA-recognition domain of MB. Thus, the fluorescent probe would be a potential alternative tool for biomedical research and clinical molecular diagnostics.
关键词：
First principles;Precipitation strengthening;Solute;Vanadium alloys
摘要：
The precipitates of second phases with coherent or incoherent interfaces can interact with dislocations to act as slip obstacles that can significantly improve the mechanics properties of alloys. In this work, the first-principles calculations based on density functional theory were performed to characterize the precipitate/Vanadium interface in the vanadium alloys and uncovering how structure of precipitations and interfacial defects (vacancy or solutes) distribution influence on the effectiveness of precipitation strengthening. Based the Baker-Nutting orientation relationship, the equilibrium stable precipitate/matrix interface structure are obtained. It is found that the so-called layer buckling exists in the interfacial region. Meanwhile, considering the equilibrium interface structure, the compressive strain is taken up by the Ti-based precipitation in the interface. For V-based precipitations, on the contrary, the interfacial strain is reversed that the tensile strain is taken up by the V-based precipitations. Under the uniaxial tensile loading, the stress-strain relations of heterostructures with different kinds of precipitates MX (M = Ti, V and X = C, N) are obtained to characterize the precipitation strengthening in the Vanadium alloys. The ideal tensile strength for heterostructure is sensitive to the size of precipitation. Furthermore, it is interesting to note that Ti-based precipitations not only improve the tensile strength, but also meliorate the ductility of the V alloys, which pointing to the inference that Ti-based precipitations are more effective to strengthen the V alloys than V-based precipitations. Our findings from this study can be implemented into providing the theoretical strategy for further design of the new style alloys. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
In this paper, we introduced a bluish violet emitting phosphor Ca3Al4ZnO10:Ti (IV) (CAZO:Ti⁴⁺) synthesized by high‐temperature solid‐state reaction. Upon 265 nm excitation, a broad emission band spanned from 300 nm to 500 nm and centered at 370 nm was observed. In addition, the effects of flux and charge compensation to photoluminescence properties of CAZO:Ti⁴⁺ were systematically investigated. The results show that 103% improvement of emission intensity was achieved when 1% H3BO3 flux was introduced and 32.8% enhancement of it for 2% Ca²⁺ vacancies doped as charge compensator. Moreover, the lifetimes, band gap energy, concentration quenching mechanism as well as electron transition process of CAZO:Ti⁴⁺ were discussed. Due to the efficient broad bluish violet emitting, this phosphor may find a potential application in mercury vapor‐excited fluorescent lamp for plant growth. This article is protected by copyright. All rights reserved.
关键词：
Batteries;Green chemistry;Electrochemical energy storage;Electrode materials;Nanomaterials
摘要：
A simple strategy which combines the treatment of industrial wastewater with the preparation of electrode materials was proposed in this work. And the industrial wastewater is the only iron source for the material preparation. The preparation method in this work is facile, economical and environment-friendly which includes two simple steps of low-temperature aqueous solution and one-step calcination. Moreover two kinds of high performance Fe2O3 anode materials (alpha-/gamma-Fe2O3 nano spheres, respectively) with isomerism can be obtained by simply adjusting calcination temperatures. Both of the alpha-Fe2O3 and gamma-Fe2O3 nanospheres show good lithium storing reversibility when used as anode materials in LIBs. Furthermore the as-prepared alpha-Fe2O3 nano-electrode with lower electrochemical impedance exhibit a far better electrochemical performance (about 74.1% capacity retention (calculated based on the lithiation) from the 1st to 5th cycle) than the gamma-one (only 39.0% capacity retention from the 1st to 5th cycle). The results here provide economical yet environment-friendly strategies for developing advanced anode material demanding both high energy and long lifespan for full-cell lithium battery. (C) 2018 Elsevier Ltd. All rights reserved.
摘要：
<p style='text-indent:20px;'>In this paper, we investigate the dynamics of the following family of rational maps</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id="FE1"> \begin{document}$ \begin{equation*} f_{\lambda}(z) = \frac{z^{2n} - \lambda^{3n+1}}{z^n(z^{2n} - \lambda^{n - 1})} \end{equation*} $\end{document} </tex-math> </disp-formula></p><p style='text-indent:20px;'>with one parameter <inline-formula><tex-math id="M1">\begin{document}$ \lambda \in \mathbb{C}^* - \{\lambda: \lambda^{2n + 2} = 1\} $\end{document}</tex-math></inline-formula>, where <inline-formula><tex-math id="M2">\begin{document}$ n\geq 2 $\end{document}</tex-math></inline-formula>. This family of rational maps is viewed as a singular perturbation of the bi-critical map <inline-formula><tex-math id="M3">\begin{document}$ P_{-n}(z) = z^{-n} $\end{document}</tex-math></inline-formula> if <inline-formula><tex-math id="M4">\begin{document}$ \lambda \neq 0 $\end{document}</tex-math></inline-formula> is small. It is proved that the Julia set <inline-formula><tex-math id="M5">\begin{document}$ J(f_\lambda) $\end{document}</tex-math></inline-formula> is either a quasicircle, a Cantor set of circles, a Sierpiński carpet or a degenerate Sierpiński carpet provided the free critical orbits of <inline-formula><tex-math id="M6">\begin{document}$ f_\lambda $\end{document}</tex-math></inline-formula> are attracted by the super-attracting cycle <inline-formula><tex-math id="M7">\begin{document}$ 0\leftrightarrow\infty $\end{document}</tex-math></inline-formula>. Furthermore, we prove that there exists suitable <inline-formula><tex-math id="M8">\begin{document}$ \lambda $\end{document}</tex-math></inline-formula> such that <inline-formula><tex-math id="M9">\begin{document}$ J(f_\lambda) $\end{document}</tex-math></inline-formula> is a Cantor set of circles but the dynamics of <inline-formula><tex-math id="M10">\begin{document}$ f_{\lambda} $\end{document}</tex-math></inline-formula> on <inline-formula><tex-math id="M11">\begin{document}$ J(f_{\lambda}) $\end{document}</tex-math></inline-formula> is not topologically conjugate to that of any known rational maps with only one or two free critical orbits (including McMullen maps and the generalized McMullen maps). The connectivity of <inline-formula><tex-math id="M12">\begin{document}$ J(f_{\lambda}) $\end{document}</tex-math></inline-formula> is also proved if the free critical orbits are not attracted by the cycle <inline-formula><tex-math id="M13">\begin{document}$ 0\leftrightarrow\infty $\end{document}</tex-math></inline-formula>. Finally we give an estimate of the Hausdorff dimension of the Julia set of <inline-formula><tex-math id="M14">\begin{document}$ f_\lambda $\end{document}</tex-math></inline-formula> in some special cases.</p>
通讯机构：
[Yu, Peng; Liu, Biqiong] H;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.;Hunan Agr Univ, Grad Sch, Changsha 410128, Hunan, Peoples R China.
关键词：
Fined-grained iron ore;CaCO3;Alkali lignin;Microwave;Silicate gangue removal
摘要：
To solve the problem of processing of refractory iron oxide ore resulted from its fine-grained disseminated structure, in this paper, an improved technology was innovatively proposed, which consisted of three stages of reduction roasting-acid leaching followed by magnetic separation, and CaCO3 was introduced during roasting process. Mechanism analyses indicated that kaolinite, a major gangue in ore, can be thermally dehydrated to amorphous metakaolin during roasting process, and CaCO3 can in part react with metakaolin-converting the stable kaolinite gangue mineral into acid-soluble Ca3Al2(SiO4)(3), and subsequently Ca3Al2(SiO4)(3) was selectively removed by acid leaching process. Moreover, the presence of CaCO3 can also improve the gathering state of Fe-rich particles, which is beneficial for magnetic separation. Iron concentrate obtained via the proposed technology contained 53.73% Fe, 9.02% Mn, 7.51% Al, and 2.46% Si, with a Fe recovery ratio of 88.20%, which surely meet the iron ore quality requirement of steel and iron industry. (C) 2019 Published by Elsevier B.V.
通讯机构：
[Xiao, FH; Huang, HW] X;Xiangtan Univ, Coll Chem, Key Lab Environm Friendly Chem & Applicat, Minist Educ,Key Lab Green Organ Synth & Applicat, Xiangtan 411105, Peoples R China.
摘要：
A copper-catalyzed oxidative cyclization of oxime, arylthiol, and trifluoroacetic anhydride for the construction of trisubstituted oxazoles has been developed. This transformation combines N–O bond cleavage, C–H functionalization, and intramolecular annulation, providing a practical protocol for the introduction of a trifluoromethyl (−CF3) group at oxazole rings.
摘要：
In this work, highly N/P co-doped porous carbons (NPCs) have been synthesized by an ultra facile, self-activation green strategy, only used L-histidine and phytic acid as precursors. With the benefit of the self-activation strategy of the precursors, no extra traditional activators are needed for porous structures of NPCs. The as-prepared NPC-0.5-800 sample displays high contents and uniform heteroatom doping (N: 5.4%, P: 6.3%, O: 12.14%), high specific surface area (787 m(2)/g) and large pore volume (0.43 cm(3)/g). These characteristics enable the NPC-0.5-800 sample to exhibit a good specific capacitance of 290.2 F g(-1) and a good cycling stability (95.0%) in a three-electrode system. Furthermore, the NPC-0.5-800-based symmetric supercapacitor in 1M NaSO4 electrolyte shows a high energy density (20.8Wh kg(-1)) at the current density of 1 A g(-1). Importantly, it exhibits excellent cycling performance (97.1% of capacitance retention after 5000 cycles). The work not only provides the self-activation green method to fabricate NPCs with good electrochemical performances, but also designs materials of different N/P content and pore size distribution for further supercapacitor applications. (C) 2019 The Electrochemical Society.
