查找使用阿拉丁产品的科研文献

Effects of active species on degrading A-ring of tetracycline in the Z-scheme heterostructured core-shell La(OH)3@BaTiO3 composition

Baolai Wang,Kaili Wei,Fuming Chen,Yinzhen Wang,Guannan He,Wei Li,Junming Liu,Qinyu He

It has been found it more difficult in completely degrading A-ring of tetracycline (TC) than completely degrading B-D rings of tetracycline. Thus, it is very necessary to find an effective route to completely degrading A-ring of tetracycline. In this work, a Z-scheme heterojuncted core-shell La(OH) 3 @BaTiO 3 composite (LB) was designed and fabricated through hydrothermal method . Many characterization techniques were employed to investigate the microstructure, phases, composition, energy band structure , and the lifetime of photogenerated carriers. In the mean time, the photocatalytic properties, including the degradation of A-ring and B-D rings of TC, as well as active species during photo-degradation were investigated. It is found that the as-prepared LB has an improved lifetime of photo-produced carriers, as well as high photocatalytic properties, being attributed to the core-shell structured heterojunction La(OH) 3 @BaTiO 3 . In addition, it is also found that ·O 2 − is more effective on degrading A-ring of TC than other active species, likely owed to the PKa3 value (3.3) of A-ring in TC. This work has supplied a route to completely degrading the A-ring of TC: rationally design and prepare a Z-scheme heterojuncted composites which supply very negative conduction band bottom potential.

A self-assembly solvothermal synthesis of SiMoVn@[Cu6O(TZI)3(H2O)6]4·nH2O for the efficient selective oxidation of various alkylbenzenes

Jiabin Liu,Yuxiang Xin,Yiyang Bai,Wei She,Jing Wang,Gaungming Li

The selective oxidation of alkylbenzenes contributes greatly to the production of high-value chemicals. However, developing novel and efficient catalysts remains a great challenge. To explore new and efficient catalysts, a series of POMs of H(4+n)SiMo(12−n)VnO40 (SiMoVn, n = 1, 2 and 3) were reacted with rht-MOF-1 ([Cu6O(TZI)3(H2O)6]4·nH2O) by a one-pot self-assembly solvothermal method. As a result, three SiMoVn@rht-MOF-1 (1, n = 1; 2, n = 2 and 3, n = 3) were isolated. Single crystal analysis revealed that SiMoVn were successfully introduced in the cages of rht-MOF-1. When complex 3 was employed as a catalyst, it effectively catalyzed the selective oxidation of alkylbenzene with a conversion of 99% and selectivity of 99% under optimized reaction conditions. Recycling experiments proved that complex 3 is stable and recyclable after six cycles. In comparison with analogous catalysts, complex 3 exhibits outstanding catalytic performance. Furthermore, the kinetics and reaction mechanism were investigated and verified by EPR and XPS analysis. This approach paves a facile route to prepare POMs@MOFs for the selective oxidation of various alkylbenzenes.

Electrocatalytic Multicomponent Transformation of Aldehyde, 5-Amino-3-methyl-1-phenylpyrazole and Dimedone: An Efficient Protocol for Substituted Pyrazolo[3,4-b]quinolines

Cunwei Qian,Ying Wang,Xian Li,Changsheng Yao

Graphical A convenient, rapid and electrochemical one-pot protocol is designed for the synthesis of pyrazolo[3,4- b ]quinolines derivatives. The reaction is carried out in an undivided cell equipped with an iron cathode and a graphite anode in the presence of sodium bromide as a supporting electrolyte. Fourteen pyrazolo[3,4- b ]quinoline derivatives are obtained under a constant current of 30 mA after 0.14 F/mol of electricity passed. A convenient, rapid and electrochemical one-pot protocol was developed successfully for the preparation of pyrazolo[3,4- b ]-quinoline derivatives. The reaction is carried out in a 25 mL three neck flask equipped with graphite electrode as anode and iron electrode as cathode (electrode area of 1 cm 2 ) with sodium bromide as supporting electrolyte at room temperature in ethanol. Fourteen pyrazolo-[3,4- b ]-quinoline derivatives were synthesized by use of various aldehyde (including aryl aldehydes and aliphatic aldehydes), dimedone and 5-amino-3-methyl-1-phenylpyrazole as substrates in good yields (76–86 %) with a constant current of 30 mA after 0.14 F/mol of electricity passed. All aimed products were characterized by IR, 1 H NMR and HRMS. Notably, the presented method features ecologically sound, simple experimental procedure and good yields.

Exploring the Effects of Cyanidin-3-O-Glucoside on Type 2 Diabetes Mellitus: Insights into Gut Microbiome Modulation and Potential Antidiabetic Benefits

Xiang Ye,Wen Chen,Fu-Jie Yan,Xiao-Dong Zheng,Peng-Cheng Tu,Peng-Fei Shan

Berries and their functional components have been put forward as an alternative to pharmacological treatments of type 2 diabetes mellitus (T2DM), and more attention has been paid to the gut microbiome in the pathophysiology of T2DM. Thus, we tried to examine the metabolic impact of red bayberry-derived cyanidin-3-O-glucoside (C3G) and investigate whether the antidiabetic effects of C3G were associated with the gut microbiome. As a result, C3G administration was found to reduce blood glucose levels of diabetic db/db mice, accompanied by increased levels of glucagon-like peptide (GLP-1) and insulin. Moreover, 16S rRNA analysis showed that the dominant microbiota modulated by C3G were pivotal in the glucose metabolism. Furthermore, the modulation of C3G on metabolic activities of gut bacteria leads to an increase in intestinal levels of key metabolites, particularly short-chain fatty acids. This contribution helps in promoting the secretion of GLP-1, which in turn increases insulin release with the purpose of reducing blood glucose levels. Overall, these findings may offer new thoughts concerning C3G against metabolic disorders in T2DM.

Lithium poly-acrylic acid as a fast Li+ transport media and a highly stable aqueous binder for Li3V2(PO4)3 cathode electrodes

Anyu Su,Qiang Pang,Xin Chen,Jiajun Dong,Yingying Zhao,Ruqian Lian,Dong Zhang,Bingbing Liu,Gang Chen,Yingjin Wei

Li3V2(PO4)3 (LVP) has been highlighted as a promising cathode material for lithium ion batteries, but it suffers from poor rate capability and rapid capacity decay due to sluggish electrode kinetics and vigorous electrode/electrolyte side reactions at high voltage. In this study, an inexpensive aqueous lithium poly-acrylic acid (LiPAA) binder was developed to deftly solve the shortcomings of the LVP material by tailoring the functional groups in the binder. The good adhesion and cohesion properties of the LiPAA binder ensured a close linkage between the active LVP particles, conductive additives and current collector, which formed a stable and conductive network in the electrode. In addition, the reversible H+/Li+ exchange in LiPAA effectively assisted the transport of Li+ ions at the electrode interface, which allowed the establishment of a Li+ conductive pathway without considerable degradation of the electrolyte. Due to these advantages, the LVP electrode containing the LiPAA binder exhibited significantly improved electrochemical performance compared to the electrode that employed the traditional polyvinylidene fluoride binder. The new electrode configuration showed a large specific capacity of 107 mA h g−1 at 70C rate and a high capacity retention of 91% was obtained after 1400 cycles at 10C rate, showcasing the great potential of this aqueous binder in lithium ion batteries.

A sensitive and rapid HPLC-DAD method for the determination of 3-hydroxy-1,2-dimethyl-4-pyridone and its distribution in rats

Mengdi Chen,Xuejiao Zhang,Shuling Li,Qiongyao Zhang

Surface-modified ammonium polyphosphate with (3-aminopropyl) triethoxysilane, pentaerythritol and melamine dramatically improve flame retardancy and thermal stability of unsaturated polyester resin

Chen Zhongwei,Yu Yuan,Zhang Qingwu,Chen Zhiquan,Chen Tingting,Li Changxin,Jiang Juncheng

Ammonium polyphosphate surface-modified by silane coupling agent (3-aminopropyl) triethoxysilane (KH-550), named STAPP, incorporated with pentaerythritol and melamine to prepare intumescent flame retardant unsaturated polyester resin (UPR/IFRs). Surface groups, surface elements, thermal stability and surface morphology of STAPP were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis (TG) and scanning electron microscopy (SEM). The flame retardancy of the UPR composites was studied by limit oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test, and its thermal stability was evaluated by TG. The results showed that IFRs greatly improves flame retardancy, thermal stability and carbon formation ability of UPR. Compared with pure UPR, when the loading of IFRs was 25 mass%, the LOI was increased from 19.8 to 41.5%, the UL-94 test reached the V-0 rating from NR, peak heat release rate and total smoke production was decreased by 54.1 and 38.7%. Furthermore, the addition of IFRs delayed the product of smoke and release heat. TG results showed that 27.6 mass% chars remained in UPR/IFRs at 1073 K, showing a good char forming ability. Besides, honeycomb-type carbon layer with few cracks and holes was observed by SEM. Finally, the flame retardancy mechanism of IFRs was elaborated in detail, which was attributed to the siloxy groups and expanded carbon layer.

Trapping [PMo12O40]3− clusters into pre-synthesized ZIF-67 toward MoxCoxC particles confined in uniform carbon polyhedrons for efficient overall water splitting

Congfang Chen,Aiping Wu,Haijing Yan,Yinglu Xiao,Chungui Tian,Honggang Fu

Bi-transition metal carbides (BTMCs) are promising in catalytic fields, but the synthesis of small-sized BTMCs remains a challenge. Here, MoxCoxC (mainly below 20 nm in size) confined in uniform carbon polyhedrons (MoxCoxC@C) was synthesized based on trapping [PMo12O40]3− (PMo12) clusters into pre-synthesized, uniform ZIF-67 (PMo/ZIF-67). The opening of the windows (0.34 nm) of ZIF-67 cages through heating is essential to allow the trapping of PMo12 into the cages. This trapping route provides a new method to successfully combine POMs and MOFs that can not be effectively combined via traditional POMOF-based (simultaneous assembly) routes. It also has advantages in controlling the uniformity and components of the materials. The size matching of PMo12 (1 nm) and the cages (1.16 nm) of ZIF-67 enables effective contact of the Co and Mo sources, thus giving small-sized MoxCoxC protected by carbon via calcination. The optimized catalysts showed good performance for water splitting with a low η10 of 83 mV (295 mV) for the hydrogen (oxygen) evolution reaction, which is superior to those derived from ZIF-67 and precursors from POMOF-based routes. Our results also indicated that the HER activity is determined by the kind of BTMC, and the activity for the OER is relative to the oxygen-containing species formed during the initial OER test.

A 3-dimensional C/CeO2 hollow nanostructure framework as a peroxidase mimetic, and its application to the colorimetric determination of hydrogen peroxide

Wang Nan,Duan Jizhou,Shi Weijie,Zhai Xiaofan,Guan Fang,Yang Lihui,Hou Baorong

Various 3-dimensional C/CeO 2 hollow nanostructure frameworks (3D C/CeO 2 HNFs) were synthesized by using a polymer blowing process that is accelerated by adding a certain amount of cerium nitrate. Polyvinylpyrrolidone was used as the polymer. The resulting HNFs were characterized by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. The HNFs possess a large specific surface area, and the CeO 2 nanocrystals consist of a single phase. The HNFs display intrinsic peroxidase-like activity and can catalyze the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine in the presence of H 2 O 2 to produce a blue product. The method was applied to the quantification of H 2 O 2 with a 5.2 nM detection limit. The analytical range is from 10 nM to 1 μM. Schematic of the preparation of a 3-dimensional C/CeO 2 hollow nanostructure framework by a polyvinylpyrrolidone-blowing process accelerated by Ce(NO 3 ) 3 . They were applied to H 2 O 2 detection by catalyzing the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to the oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) to produce blue-color reaction.

Thermochemical properties of alkaline-earth metals borates of a series of MB8O11(OH)4·xH2O (M = Ca, Sr, Ba; x = 0, 3)

Jun-Feng Wang,Pan Liang

A pure barium borate of BaB 8 O 11 (OH) 4 ·3H 2 O has been synthesized and characterized by XRD, FT-IR, TGA, and chemical analysis. The molar enthalpies of solution of BaB 8 O 11 (OH) 4 ·3H 2 O in 1 mol dm −3 HCl(aq), and Ba(OH) 2 ·8H 2 O in the mixture solvent of {2.00 cm 3 of 1 mol·dm −3 HCl + H 3 BO 3 (aq)} were measured by microcalorimeter at T  = 298.15 K, respectively. With the use of previously determined enthalpy of solution of H 3 BO 3 (s) in 1 mol·dm −3 HCl(aq), and the standard molar enthalpies of formation for Ba(OH) 2 ·8H 2 O(s), H 3 BO 3 (s), and H 2 O(l), the standard molar enthalpy of formation of −(7500.6 ± 6.5) kJ·mol −1 at T  = 298.15 K was obtained based on an appropriate thermochemical cycle. Moreover, the molar enthalpy of formation of −6091.7 kJ mol −1 for [B 8 O 11 (OH) 4 ] 2− was estimated by a group contribution method, which was used to predict the Δ f H m o of a series of alkaline-earth metal borates for MB 8 O 11 (OH) 4 (M = Ca, Sr, Ba).

Effective synthesis of theaflavin-3,3′-digallate with epigallocatechin-3-O-gallate and epicatechin gallate as substrates by using immobilized pear polyphenol oxidase

Shicheng Lei,Minhao Xie,Bing Hu,Li Zhou,Yi Sun,Muhammad Saeeduddin,Hongcheng Zhang,Xiaoxiong Zeng

In the present study, pear polyphenol oxidase (PPO) was purified, immobilized and applied for the synthesis of theaflavin-3,3′-digallate (TF3). Firstly, PPO of pear ( Pyrus bretschneideri Rehd cv. Huangguan) was purified 24.36-fold in specific activity with a recovery of 6.77% by sequential use of precipitation with 70% saturated ammonium sulfate and chromatography of DEAE-Sepharose Fast Flow column. The purified pear PPO, found to be a dimer of identical subunits of molecular mass 35   kDa, was then successfully immobilized onto Fe 3 O 4 /chitosan nanoparticles via glutaraldehyde coupling reaction. Finally, TF3 was effectively synthesized by applying the immobilized PPO as biocatalyst with epicatechin gallate (ECG) and epigallocatechin-3- O -gallate (EGCG) as substrates, and the maximum yield of TF3 was 42.23% based on the amount of ECG added. In addition, the immobilized enzyme still remained 85% of its initial ability after successive usage of 8 cycles and could be stored for 30   days with less loss of activity. All the results suggest that the developed procedure is quite useful and has great potential for synthesis of TF3 and other theaflavins.

Strategy of Fusion Covalent Organic Frameworks and Molecularly Imprinted Polymers: A Surprising Effect in Recognition and Loading of Cyanidin-3-O-glucoside

Qianyu Zhao,Hua Zhang,Haitian Zhao,Jia Liu,Jingyi Liu,Zilong Chen,Bin Li,Xiaojun Liao,Joe Mac Regenstein,Jing Wang,Xin Yang

Seven magnetic covalent organic framework molecularly imprinted polymers with magnetic responsiveness, large specific surface area, and molecular recognition ability were successfully synthesized, suitable for the separation of cyanidin-3-O-glucoside from complex samples. Using a room-temperature synthesis strategy, covalent organic frameworks accompanied by imprinted sites were formed in one step on the functionalized magnetic nanoparticles with 1,6-hexanediamine. The composite materials were easy to prepare and showed high adsorption capacity (127 mg g–1) together with favorable adsorption selectivity for cyanidin-3-O-glucoside over other flavonoids and phenolic acids. Magnetic covalent organic framework molecularly imprinted polymers exhibited good stability in 10 adsorption–desorption cycles. This work established a new method of extracting and separating high-purity anthocyanins and even unstable natural compounds.