查找使用阿拉丁产品的科研文献

Synthesis and antifouling performance of tadpole-shaped poly(N-hydroxyethylacrylamide) coatings

Yanping Cao,Shengjie Liu,Zhaoqiang Wu,Hong Chen

Linear poly(N-hydroxyethylacrylamide) (PHEAA) is regarded as one of the most promising antifouling materials because of its excellent antifouling properties and good hemocompatibility. However, the antifouling performance of topological PHEAAs remains largely unknown. Herein, the preparation of antifouling surfaces based on a tadpole-shaped PHEAA coating is reported for the first time, and how the tadpole-shaped PHEAA architecture affects antifouling performance is investigated. It is shown that the tadpole-shaped PHEAA-modified surfaces exhibit better antifouling performance than linear copolymer precursor-modified surfaces with identical molar masses and chemical compositions. This may be primarily attributed to the presence of cyclic PHEAA head chain segments in the tadpole-shaped PHEAA copolymer, and the absence of interchain entanglements can facilitate the formation of smoother and densely packed grafts, which result in better antifouling properties.

Mussel-inspired synthesis of magnetic N-Halamine nanoparticles for antibacterial recycling

Danxia Chai,Wenxin Liu,Xiufeng Hao,Heyuan Wang,Haixiao Wang,Yujiao Hao,Yue Gao,Huihui Qu,Lifang Wang,Alideertu Dong,Ge Gao

Antibacterial N -halamine coatings are successful in avoiding and eliminating bacterial infections caused by bacterial contamination and biofilms on the surfaces. However, the N -halamine coatings remain a long-standing challenge faced by our healthcare system. Herein we reported a new mussel-inspired surface modification strategy to achieve N -halamine copolymer coatings with adhesive effects. The phenolic hydroxyl groups from N -halamine copolymers are used for ligand exchange with oleic acid on the magnetic Fe 3 O 4 nanoparticles for binding the N -halamine copolymer onto the surface of the nanoparticles. The as-synthesized N -halamine coatings endow the magnetic Fe 3 O 4 nanoparticles antibacterial activity toward both Gram-negative bacteria ( Escherichia coli ) and Gram-positive bacteria ( Staphylococcus aureus ). Since the super-paramagnetism of Fe 3 O 4 in core, the N -halamine coatings are separable magnetically and remain high inactivating efficiency toward bacteria even after five cycles. We believe that, with the advantage of mussel-inspired strategy, the N -halamine coatings should have great potential for use in antibacterial and biomedical fields.

Point defect engineering and machinability in n-type Mg3Sb2-based materials

Juan Li,Shuai Zhang,Fei Jia,Shuqi Zheng,Xiaolei Shi,Daqiang Jiang,Siyu Wang,Guiwu Lu,Liming Wu,Zhi-Gang Chen

Approaching practical thermoelectric devices require high-performance and machinable thermoelectric materials . However, the currently available materials are usually brittle. In this work, Nd-doped Mg 3 Sb 2 -based compounds exhibit not only excellent thermoelectric performance but also superior machinability . Mg 3.2 Nd 0.03 Sb 1.5 Bi 0.5 exhibits a high power factor of 20.6 μW cm −1  K −2 at 725 K and a peak zT of 1.8, which mainly originates from the increased n of ~8 × 10 19  cm −3 by Nd/Mg substitutional defects. Defect calculations predict that other rare earth elements (Sm, Gd, Tb, Dy and Ho) have the same effect as Nd on Mg 3 Sb 2 and the predicted highest achievable electron concentrations at 700 K are ~10 20  cm −3 . The measured hardness, Young's modulus and fracture toughness of Mg 3.2 Nd 0.03 Sb 1.5 Bi 0.5 are 1.1 GPa, 49.8 GPa and 1.4 MPa m 1/2 , respectively. In addition, the sample can be easily machined into the dog-bone shape with external thread at both ends, indicating the excellent machinability of Mg 3 Sb 2 -based materials. This work suggests a bright future of Mg 3 Sb 2 -based thermoelectric materials for practical applications and device fabrication .

Visible-light-mediated Synthesis of Bromo-containing Azaspirotrienediones from N-phenylpropynamides

Yuan Chen,Fo-Yun Lu,Rui-Xue Li,Zhi Guan,Yan-Hong He

Graphical A visible light-mediated reaction of N -phenylpropynamide with diethyl 2,2-dibromomalonate has been developed for the synthesis of bromo-substituted azaspirotrienedione. This method avoids the use of transition metals, peroxides and other substances that are harmful to the environment. Through radical addition/ipso-cyclization/oxidation cascade reaction, C−Br, C−C and C=O bonds can be formed in one pot. Various substituents of N -arylpropynamide are well tolerated and yield of the target product is up to 95%. A visible-light-mediated reaction of N -phenylpropynamides with diethyl 2,2-dibromomalonate for the synthesis of bromo-substituted azaspirotrienediones has been developed. This method allows the formation of C−Br, C−C and C=O bonds in one pot via a cascade radical addition/ipso-cyclization/oxidation process. A possible radical mechanism involving single electron transfer and energy transfer processes is proposed based on control experiments, cyclic voltammetry determination and Stern-Volmer quenching experiments.

Effect of N-terminal modification on the antimicrobial activity of nisin

Xuejian Yu,Naiyan Lu,Jiyue Wang,Zhe Chen,Chen Chen,Joe Mac Regenstein,Peng Zhou

Nisin, the only antimicrobial peptide that has GRAS (generally considered as safe) status from both WHO and FDA, has the potential to become an important natural antibiotic as bacteria become more resistant to traditional antibiotics. Many studies have focused on how modification of nisin affects antimicrobial activity. In this study, nisin and chitosan were crosslinked using genipin to modify the N-terminal of nisin. The antimicrobial experiments were carried out on Staphylococcus aureus ATCC 6538. The results showed that nisin still retained antimicrobial activity after modification. When the crosslinking ratio of nisin to chitosan increased to 200: 1, MIC decreased from 48 μg/ml to 40 μg/ml. Less chitosan increased local number density and antimicrobial activity of nisin. When the local number density was high, adjacent peptides could cooperatively penetrate into the lipid membrane. The results of this study may help to better understand the antimicrobial mechanism and provide suggestions for the further modification of nisin.

Zeolitic imidazolate framework derived Fe-N/C for efficient microwave absorbers

Jiahao Yu,Jieyi Yu,Tongpan Ying,Xianguo Liu,Xuefeng Zhang,Dandan Han

Three main strategies for designing efficient microwave absorber includes the intrinsic dielectric/magnetic properties, the novel structure and the single atom doping. The Fe-N/C nanocomposites integrate the advantages of above three strategies into one system. In this work, the method for preparing Fe-N/C nanocomposite by calcining the FePc@ZIF-8 precursor under a flowing N 2 gas is described. Fe-N/C nanocomposites, displaying respectable dodecahedron-like morphology, have the merits of strong absorption ability, wide effective absorption bandwidth, thin thickness, and excellent microwave absorption efficiency, which are attributed to the synergistic effect of good electromagnetic loss capacity and proper impedance matching originating from intrinsic dielectric/magnetic properties, the novel structure and the single atoms (Fe and N) doping. Fe-N/C-24 composite delivers an optimal reflection loss of −30.98 dB, an effective absorption bandwidth of 5.04 GHz, the microwave absorption capacity of 87.61 dB GHz the absorption efficiency of 51.53 dB GHz/mm at 1.7 mm.

Acetone dissolution to prepare N-doped hierarchical porous carbon for supercapacitor

Chang Ma,Lei Liu,Fang Zhang,Yue Zhang,Senlin Hou,Aibing Chen

The hierarchical porous carbon (HPC) materials have rich porous structure , high specific surface area and reasonable porosity for a wide range of applications in many fields, such as catalysis, adsorption, and energy storage, etc. Although some synthetic strategies have been developed, efficient preparing HPC materials remains challenging. In this work, we propose a method to prepare N-doped hierarchical porous carbon (NHPC) by acetone dissolution following co-assembly process. 1-Alkyl-3-methyl imidazole bromide ([C 18 Mim]Br), tetraethyl orthosilicate (TEOS) and resorcinol-formaldehyde were co-assembled to form a pleated sheet composite material, where [C 18 Mim]Br induced formation of the sheet structure and also led to nitrogen doping in the carbon skeleton. TEOS created a mesoporous structure and increased specific surface area, while acetone dissolved the oligomer of the resin, creating a macroporous structure, but destroying the morphology of the sheet. At an appropriate amount of acetone, the resulting NHPC exhibits the hierarchical porous structure, high specific surface area and N-doping characteristics. When used as a supercapacitor material, NHPC exhibits the specific capacitance is as high as 241 F g −1 at 1 A g −1 . Furthermore, the symmetric supercapacitor manufactured with NHPC has a power density of 4.1 kW kg −1 , an energy density of 2.56 Wh kg −1 , and demonstrates excellent cycle stability of up to 92.82%, exhibiting the potential as good supercapacitor materials.

Gut microbiota dependent trimethylamine N-oxide aggravates angiotensin II–induced hypertension

Shan Jiang,Yongjie Shui,Yu Cui,Chun Tang,Xiaohua Wang,Xingyu Qiu,Weipeng Hu,Lingyan Fei,Yun Li,Suping Zhang,Liang Zhao,Nan Xu,Fang Dong,Xiaoqiu Ren,Ruisheng Liu,Pontus B. Persson,Andreas Patzak,En Yin Lai,Qichun Wei,Zhihua Zheng

Gut microbiota produce Trimethylamine N-oxide (TMAO) by metabolizing dietary phosphatidylcholine, choline, l -carnitine and betaine. TMAO is implicated in the pathogenesis of chronic kidney disease (CKD), diabetes, obesity and atherosclerosis. We test, whether TMAO augments angiotensin II (Ang II)-induced vasoconstriction and hence promotes Ang II-induced hypertension. Plasma TMAO levels were indeed elevated in hypertensive patients, thus the potential pathways by which TMAO mediates these effects were explored. Ang II (400 ng/kg −1 min −1 ) was chronically infused for 14 days via osmotic minipumps in C57Bl/6 mice. TMAO (1%) or antibiotics were given via drinking water. Vasoconstriction of renal afferent arterioles and mesenteric arteries were assessed by microperfusion and wire myograph, respectively. In Ang II-induced hypertensive mice, TMAO elevated systolic blood pressure and caused vasoconstriction, which was alleviated by antibiotics. TMAO enhanced the Ang II-induced acute pressor responses (12.2 ± 1.9 versus 20.6 ± 1.4 mmHg; P < 0.05) and vasoconstriction (32.3 ± 2.6 versus 55.9 ± 7.0%, P < 0.001). Ang II-induced intracellular Ca 2+ release in afferent arterioles (147 ± 7 versus 234 ± 26%; P < 0.001 ) and mouse vascular smooth muscle cells (VSMC, 123 ± 3 versus 157 ± 9%; P < 0.001 ) increased by TMAO treatment. Preincubation of VSMC with TMAO activated the PERK/ROS/CaMKII/PLCβ3 pathway. Pharmacological inhibition of PERK, ROS, CaMKII and PLCβ3 impaired the effect of TMAO on Ca 2+ release. Thus, TMAO facilitates Ang II-induced vasoconstriction, thereby promoting Ang II-induced hypertension, which involves the PERK/ROS/CaMKII/PLCβ3 axis.

N-Doped Porous Carbon Supported Au Nanoparticles for Benzyl Alcohol Oxidation

Mao Donglei,Jia Mingmin,Qiu Jianhao,Zhang Xiong-Fei,Yao Jianfeng

Abstract N-doped porous carbon (NPC) was produced through a simple and efficient method using biomass-derived pine sawdust as the carbon source, NH 4 Cl as nitrogen source and NaHCO 3 as the activator. Both NPC and porous carbon (PC, prepared without nitrogen-doping) were used as support for Au nanoparticles to catalytic oxidation of benzyl alcohol. As expected, Au/NPC performs a substantially enhanced catalytic activity for benzyl alcohol oxidation in comparison with that of Au/PC (conversion of benzyl alcohol is 98.9% for Au/NPC and 51.4% for Au/PC under the same condition). The better catalytic performance of Au/NPC should be due to the introduction of N atoms into PC support, which not only adsorbs the benzyl alcohol molecules more easily, but also makes the Au nanoparticles smaller and more dispersed. Our experimental results also show that mild temperature (60 °C) is more beneficial for the reaction, O 2 atmosphere is a necessity for benzyl alcohol oxidation and Au/NPC can also be used to catalyze oxidation of other aromatic alcohols. Graphic Abstract

Anion exchange membranes with dense N-spirocyclic cations as side-chain

Fang Hua Liu,Qian Yang,Xue Lang Gao,Hong Yue Wu,Qiu Gen Zhang,Ai Mei Zhu,Qing Lin Liu

To prepare anion exchange membranes (AEMs) with high performances, we tethered the as-synthesized oligomers with dense N-spirocyclic cations (NS) as the side-chain to poly(ether sulfone) (PES). The steric hindrance of spirocyclic structure and electron-donating effect of alkyl spacers significantly enhance the stability of cations in harsh alkaline and high hydration conditions. Correspondingly, the ionic exchange capacity (IEC) of PES–NS–10% only decreased by 13.8% and the conductivity remained 84.3% after being immersed in harsh environment (80 °C, 2 M NaOH) for 864 h. In addition, the high density of N-spirocyclic cations in the side-chain benefits the formation of clear microphase separation , as confirmed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The highest conductivity of 95.5 mS cm -1 was achieved by PES–NS–10% at 80 °C while the corresponding swelling ratio was only 7.69%. Furthermore, the single cell assembled with PES–NS–10% showed a peak power density of 110.1 mW cm -2 at 300 mA cm -2 . Durability test of the single cell based on PES–NS–10% under 100 mA cm -2 also demonstrates that the as-prepared AEMs with NS have potential application for fuel cells.

Nanoparticles Assembled CdIn2O4 Spheres with High Sensing Properties towards n-Butanol

Weiping Liu,Ximing Zhang,Zhaofeng Wang,Ruijian Wang,Chen Chen,Chengjun Dong

Cd/In-glycerate spheres are synthesized through a simple solvothermal method. After thermal treatment, these Cd/In-glycerates can be converted into CdIn2O4spheres. Many characterization methods were performed to reveal the microstructure and morphology of the CdIn2O4. It was found that pure CdIn2O4phase was obtained for the Cd/In starting materials at ratios of 1:1.6. The CdIn2O4spheres are composed by a large number of nanoparticles subunits. The CdIn2O4sphere-based sensor exhibited a low detection limit (1 ppm), high response (81.20 to 500 ppm n-butanol), fast response (4 s) and recovery (10 s) time, good selectivity, excellent repeatability, and stability at 280 °C. Our findings highlight the possibility to develop a novel gas sensor based on CdIn2O4for application in n-butanol detection with high performance.Keywords:gas sensor;n-butnaol;CdIn2O4;spheres;solvothermal method

Synthesis, surface and interface tension of N-lauroyl-L-Valine sodium

Cong Luo,Bo Yang,Jian Yang,Yawen Zhou,Changyao Liu,Baocai Xu