作者机构:
[Zhang, Youyu; Wu, Tengteng; Ma, Zhangyan; Liu, Meiling; Hou, Wenli; Yao, Shouzhuo] Hunan Normal Univ, Coll Chem & Chem Engn, Minist Educ, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.;[Liu, Xiaoying] Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
通讯机构:
[Liu, Meiling; Liu, Xiaoying] H;Hunan Normal Univ, Coll Chem & Chem Engn, Minist Educ, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
关键词:
*3,3,5,5-Tetramethylbenzidine;*Colorimetric assay;*Enzyme mimic;*Inhibition;*Nanocubes;*Peroxidase mimetic;*Prussian White
摘要:
Colorimetric methods are described for the determination of ascorbic acid (AA) and alkaline phosphatase (ALP). Both assays are based on the inhibition of the peroxidase (POx)-like activity of Prussian Blue nanocubes (PB NCs) capped with citric acid. They catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to produce a blue color with an absorption maximum at 652 nm. On addition of AA, the PB NCs are reduced to Prussian White (PW) which does not act as a POx mimic. This results in a decreased rate of the formation of the blue coloration whose intensity decreases with increasing concentration of AA. The assay allows AA to be quantified with a 35 nM detection limit (at 3sigma/m). The hydrolysis of AA phosphate by ALP leads to the formation of AA which can be quantified by the above method. Based on this, the activity of ALP can be determined by measurement of the intensity of the blue coloration thus formed. The method can be used to determine the activity of ALP with a detection limit as low as 0.23 U.L(-1). Graphical abstract Schematic presentation of a method for colorimetric determination of ALP activity. AA obtained by ALP-catalyzed hydrolysis of ascorbic acid phosphate (AAP) inhibits the intrinsic peroxidase-like activity of PB NCs by reducing Prussian Blue nanocrystals (PB NCs) to form inactive Prussian White (PW).
通讯机构:
[Yang, Luo] X;Xiangtan Univ, Key Lab Green Organ Synth & Applicat Hunan Prov, Key Lab Environmentally Friendly Chem & Applicat, Coll Chem,Minist Educ, Xiangtan 411105, Hunan, Peoples R China.
摘要:
A convenient Cu-promoted three-component decarbonylative alkylative arylation of terminal alkynes with aliphatic aldehydes and arenes is developed to provide chain elongated tri-substituted olefins with good chemo-, regio- and stereo-selectivities, and is applied to the radical-type decarbonylative coupling of sugar analogs. Readily available aliphatic aldehydes are readily decarbonylated into 1˙, 2˙ and 3˙ alkyl radicals for the construction of a C(sp3)–C(sp2) bond via radical addition, followed by HAS-arylation to form the C(sp2)–C(sp2) bond.
关键词:
Cobalt oxide;Hexagonal prisms;Pure phase;Anode;Lithium ion battery
摘要:
In this research, we use a modified sol-gel method to obtain a pure phase new hexagonal CoO on reduced graphene oxide by leading of polar solvent. In the electrochemical test, the CoO/rGO composite shows a remarkable performance of capacity as an anode of a lithium ion battery. The electrochemistry performance shows that the capacity of the composite can remain at 1300 mAh/g in 100 cycles without damping. The pure phase of CoO and its hexagonal morphology have been characterized by XRD, SEM and TEM. (C) 2018 Elsevier B.V. All rights reserved.
摘要:
An efficient synthetic route to chiral allylic amines has been developed by nickel/(S,S)-Ph-BPE complex catalyzed chemoselective asymmetric hydrogenation of alpha,beta-unsaturated ketoimines. Varieties of alpha,beta-unsaturated ketoimines have been well tolerated in this transformation to give chiral allylic amines with high yields and excellent ee values (up to 99% yield, up to 99% ee). A gram-scale reaction with 0.2 mol % catalyst loading has also been achieved.
通讯机构:
[Deng, GJ; Huang, HW] X;Xiangtan Univ, Minist Educ, Key Lab Environmentally Friendly Chem & Applicat, Coll Chem,Key Lab Green Organ Synth & Applicat Hu, Xiangtan 411105, Peoples R China.
摘要:
A three-component cascade bis-heteroannulation reaction is described that provides access to a variety of benzo[4,5]thieno[3,2-c]isoquinoline and thieno[3,2-c]isoquinoline compounds from easily available methylketoximes, o-halobenzaldehydes, and elemental sulfur. Mechanistic studies reveal a two-step process involving a sequential copper and sulfur catalysis relay.
关键词:
integral equations;Lane-Emden system;conformal invariance;positive solutions;existence
摘要:
This paper is devoted to studying the existence of positive solutions for the following integral system \(\left\{ {\begin{array}{*{20}{c}} {u\left( x \right) = \int_{{\mathbb{R}^n}} {{{\left| {x - y} \right|}^\lambda }{v^{ - q}}\left( y \right)dy,} } \\ {v\left( x \right) = \int_{{\mathbb{R}^n}} {{{\left| {x - y} \right|}^\lambda }{u^{ - p}}\left( y \right)dy,} } \end{array}} \right.p,q > 0,\lambda \in \left( {0,\infty } \right),n \geqslant 1\). It is shown that if (u, v) is a pair of positive Lebesgue measurable solutions of this integral system, then \(\frac{1}{{p - 1}} + \frac{1}{{q - 1}} = \frac{\lambda }{n}\), which is different from the well-known case of the Lane-Emden system and its natural extension, the Hardy-Littlewood-Sobolev type integral equations.
摘要:
A DNA-templated copper nanoparticle (CuNP) probe has been developed for the determination of the human immunodeficiency virus oligonucleotide (HIV-DNA). The function of the probe relies on affinity binding-induced DNA hybridization associated with the use of double G-quadruplexes. Double-stranded DNA (dsDNA) with poly(AT-TA) bases was used as a template for synthesis of dsDNA-CuNPs. These have weak fluorescence. In the next step, two G-rich sequences that are linked to both sides of the ds-DNA are locked by HIV complementary DNA (cDNA). If HIV-DNA is introduced, it will hybridize with cDNA, thereby transforming the two G-rich sequences into G-quadruplexes. This enhances the fluorescence of the adjacent dsDNA-CuNPs. Fluorescence increases linearly in the 1 to 200 and 250-1000 nM HIV-DNA concentration range, and the detection limit is 13 pM. This enzyme-free fluorometric assay is time-saving, easily operated, and therefore has large potential in biosensing because it may be extended to various other DNA targets. Graphic abstract Double-strand DNA-templated copper nanoparticles (DNA-CuNPs) have weak fluorescence. When Human Immunodeficiency Virus oligonucleotide (HIV-DNA) is added, it completely hybridized with HIV complementary DNA (cDNA). As a result, the two exposed G-rich sequences are transformed into G-quadruplexes, and an apparent increase in the fluorescence intensity can be observed. (AA: ascorbic acid).
摘要:
We present an atomistic simulation study on the compositional arrangements throughout Cu-Pt icosahedra, with a specific focus on the effects of inherent strain on general segregation trends. The coexistence of radial and site-selective segregation patterns is found in bimetallic nanoparticles for a broad range of sizes and compositions, consistent with prior analytical and atomistic models. Through a thorough comparison between the composition patterns and strain-related patterns, it is suggested that the presence of gradient and site-selective segregation is natural to largely relieve the inherent strain by preferential segregation of big atoms at tensile sites and vice versa, as previously hypothesized in the literature. Analogous to the case of single crystal particles, Cu-rich surface and damped oscillations can also be found in the outer shells of icosahedra, which are dominated by the lowering of both the surface energy and the chemical energy. The thermodynamic stability of segregated icosahedra is similar to segregated cuboctahedra but higher than disordered bulk alloys, validating prior thinking that element segregation driven by strain relief can extend the stability range of multiply-twinned nanoparticles. Our work sheds new light on understanding strain-induced segregation in multiply-twinned nanosystems that have elements with large lattice mismatch and strong alloying ability.
期刊:
Journal of Physical Chemistry Letters,2019年10(20):6219-6226 ISSN:1948-7185
通讯作者:
Tang, Jianfeng;Prezhdo, Oleg V.
作者机构:
[Tang, Jianfeng; Li, Wei] Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.;[Vasenko, Andrey S.] Natl Res Univ Higher Sch Econ, Moscow 101000, Russia.;[Prezhdo, Oleg V.] Univ Southern Calif, Dept Chem, Los Angeles, CA 90089 USA.
通讯机构:
[Tang, Jianfeng] H;[Prezhdo, Oleg V.] U;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.;Univ Southern Calif, Dept Chem, Los Angeles, CA 90089 USA.
摘要:
Lead halide perovskites constitute a very promising class of materials for a broad range of solar and optoelectronic applications. Perovskites exhibit many unusual properties, and recent experiments demonstrate an unusual temperature dependence of charge carrier lifetimes. Focusing on the all-inorganic CsPbBr3, and using a combination of ab initio nonadiabatic molecular dynamics and time-domain density functional theory, we demonstrate that the unconventional behavior arises because of a highly anharmonic nature of atomic motions in perovskites. As temperature increases, perovskite structure undergoes a notable deformation, reflected in tilting of octahedral units, and experiences large-scale anharmonic movements away from the equilibrium geometry. As a result, the electronic energy gap increases, and phonon-induced loss of coherence within the electronic subsystem accelerates. These two factors slow down nonradiative electron-hole recombination, which constitutes the main limitation on efficiencies of perovskite solar, optical, and electronic devices. The increase of charge carrier lifetimes with temperature is particularly beneficial in applications, because materials heat up, for instance, from sunlight during solar energy harvesting. The behavior of the all-inorganic halide perovskite investigated here is different from that of hybrid organic-inorganic perovskites, which exhibit additional disorder associated with reorientations of the asymmetric organic cations. The reported simulations generate an in-depth understanding of the unusual properties of inorganic perovskites, relevant for photocatalytic, photovoltaic, electronic, and optical applications.
期刊:
New Journal of Chemistry,2019年43(15):6010-6020 ISSN:1144-0546
通讯作者:
Zhou, Wen;Zhou, Li
作者机构:
[Fu, Kaishuo; Yuan, Sisi; Zhou, Wen; Huang, Weiping; Li, MaoLin] Guangzhou Univ Chinese Med, Sch Pharmaceut Sci, Waihuan Rd, Guangzhou 510006, Guangdong, Peoples R China.;[Jiang, Zhilin] Puer Univ, Puer, Yunan, Peoples R China.;[Shi, Yonghui] Sun Yat Sen Univ, Sun Yat Sen Mem Hosp, Dept Pharm, Guangzhou 510120, Guangdong, Peoples R China.;[Chen, YongJun] Guangzhou Univ Chinese Med, South China Res Ctr Acupuncture & Moxibust, Med Coll Acu Moxi & Rehabil, Waihuan Rd, Guangzhou 510006, Guangdong, Peoples R China.;[Zhou, Li] Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
通讯机构:
[Zhou, Wen] G;[Zhou, Li] H;Guangzhou Univ Chinese Med, Sch Pharmaceut Sci, Waihuan Rd, Guangzhou 510006, Guangdong, Peoples R China.;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
摘要:
The tumor-seeking role of bleomycin (BLM) disaccharide has been demonstrated to serve as a promising tool for cancer diagnosis and a potential ligand for targeted therapy. However, these practical applications are often hampered by the lack of BLM disaccharide. Herein, an efficient multi-gram synthesis of peracetylated BLM disaccharide 20 is achieved by a TMSOTF-mediated glycosidation coupling manner in 43.6% overall yield in terms of benzyl galactoside. The critical innovation of the synthetic strategy is that inexpensive benzyl galactoside was first adopted to prepare an l-gulose subunit 3 as a glycosyl acceptor, with a much shorter route in 73.0% yield, and a 3-O-carbamoyl-mannose donor 4 was achieved in 47.2% yield by lowering the amount of dibutyltin oxide, and merging aminolysis and selective deacetylation into a one-pot reaction. Next, the incorporation of BLM disaccharide into 10-hydroxycamptothecin (10-HCPT), a non-specific model compound, to form conjugate 1 could significantly improve the antitumor activity and display obvious selectivity toward cancerous and normal cells in comparison with 10-HCPT. Moreover, BLM disaccharide itself was non-cytotoxic, clearly indicating the importance and potential of BLM disaccharide in solving the targeted antitumor therapy of cytotoxic drugs.
摘要:
Herein, we have revealed elemental sulfur- and iodine reagent-mediated indole C3 arylations using cyclohexanones as the arylating reagent. This protocol provides an efficient gram-scalable access to 3-arylindole and benzo[4,5]thieno[2,3-b]indole motifs with a broad range of compatible functionalities.