INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2024
·
IF 3.8
Ci Li,Conghui Che,Fang Li,Wei Xue,Jing Li,Xinqiang Zhao,Yanji Wang
Ce-based composite oxides were used for catalyzing the methyl N-phenyl carbamate (MPC) synthesis from aniline and dimethyl carbonate. Among them, CuO–CeO2 exhibited the best catalytic performance. Characterization results showed that the second metal (Cu, Zn, Mn, Co, and Zr) can be doped into the CeO2 lattice and led to strong interactions, modifying the content of Ce3+, oxygen vacancy, and acidity of the catalyst. Notably, Ce3+, oxygen vacancies, and weak Lewis acid sites are beneficial to MPC synthesis. Additionally, CuO–CeO2–M, prepared by mechanical mixing, exhibited better catalytic activity than CuO–CeO2–C prepared by co-precipitation. This was due to the preparation method affecting the interaction between CuO and CeO2. CuO primarily interacted with CeO2 through interfacial contact in CuO–CeO2–C, whereas the interaction in CuO–CeO2–M involves both this interfacial contact effect and the presence of solid solution structures, thereby influencing the content of Ce3+, oxygen vacancy, and acidity.
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ACS Applied Nano Materials
·
2024
·
IF 5.3
Suqiong Xu,Peng Liao,Jiawei Zhu,Wei Ling,Xianke Zhang,Jujun Yuan,Chuicai Rong,Xiaoqing Liu,Zuzhou Xiong
Herein, an efficient one-dimensional (1D) N-doped Co/C nanotube absorber was designed by a cobalt source and solvent ratio comodulation strategy. First, we explored the influences of different cobalt sources (CoCl2, Co(OAc)2, Co(NO3)2, and CoSO4) on the morphology and microwave absorption (MA) property, which showed that CoCl2 facilitated the formation of nanotubes with a relatively uniform diameter and length. Notably, the Co/C nanotubes displayed an ultrawide effective absorption bandwidth (EAB) of 6.885 GHz at 2.2 mm when the filling ratio was only 8 wt %. Then, by adjusting the solvent ratio of isopropanol (IPA) and water, Co/C showed a strong absorption of −44.51 dB with an EAB of 5.44 GHz at 2.35 mm. The outstanding MA performance is ascribed to the synergistic effect of dielectric and magnetic components, which is conducive to optimizing the impedance matching, thus broadening the EAB. In addition, the 1D nanostructure is good for constructing three-dimensional (3D) conductive networks and enhancing conductive loss. Since Co nanoparticles are wrapped in carbon nanotubes (CNTs), the confinement effect can effectively prevent the agglomeration of ferromagnetic nanoparticles, adjusting the MA performance. It is worth mentioning that the maximum Radar cross section (RCS) value of Co/C can be reduced by 28.8 dB m2. Furthermore, the RCS values are all lower than −10 dB m2 from −90 to 90° and the minimum RCS value can reach −46.8 dB m2. This work provides a strategy for designing lightweight MA absorbers with strong RL and ultrawide EAB.
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APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Jun Li,Peng Huang,Xiaoqi Cheng,Rongmin Wang,Yufeng He,Pengfei Song
Bacterial contamination in water bodies is potentially transmissible to humans, making water bodies a major pathway of bacterial transmission. However, existing hydantoin copolymer nanoparticles did not achieve the regulation of nanoparticle dispersion and particle size by adjusting the ratio of hydrogen-donors and hydrogen-acceptors. To tackle this issue, amphiphilic hydantoin copolymer nanoparticles (P(VBDH-BA-NVP)NPs) were synthesized by modulating hydrogen-donors and hydrogen-acceptors using emulsion polymerization, and amphiphilic N-halamine copolymer nanoparticles (P(ClV-BA-NVP)NPs) were subsequently prepared via chlorination treatment. Impressively, nanoparticle dispersion and particle size were modulated by adjusting the ratio of hydrogen-donors and hydrogen-acceptors. With the increase of nanoparticle dispersion and the decrease of particle size, the active chlorine content was gradually enlarged, and the antibacterial performance was progressively enhanced against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). More importantly, amphiphilic N-halamine copolymer nanoparticles with two-dimensional dispersing (2DD-P(ClV-BA-NVP)NPs) exhibited excellent antibacterial properties, which benefited from the dual coordination of direct contact killing and indirect release killing in aqueous medium. Through designing P(VBDH-BA-NVP)NPs with hydrogen bond interactions, this approach aims to achieve the constitutive relationship between the effective exposure of active sites and the antibacterial effect.
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OPTICAL ENGINEERING
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2012
·
IF 0.959
Hongyan Zhang,Xiaoyi Lv,Changwu Lv,Zhenhong Jia
Highly active and sensitive surface-enhanced Raman scattering (SERS) substrates were prepared by n -type (1 to 10 Ω⋅cm in resistivity) porous silicon (PS) substrates of Ag nanoparticles. SERS studies were carried on these substrates with R6G as a test molecule with a λ ex =785 nm laser. We optimized the fabrication procedure, which is easy and rapid, for nanostructured silver particles on the surface of PS. The maximum of SERS enhancement for R6G is observed for PS with an anodization current density of 6 mA/cm 2 and an etching time of 8 min. The detection limit for R6G absorbed on Ag-coated PS (Ag-PS) is 10 nM and SERS spectra show that the Ag-PS substrate has high SERS activity. The larger pore diameter of this new Ag-PS substrate is expected and the size of the pore diameter is about 1.2 μm, which permits better biomolecule infiltration. This new Ag-PS substrate can be applied in SERS in biochemical and biomedical fields.
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JOURNAL OF PEST SCIENCE
·
2012
·Vol. 86
·期 2
·353-360
·
IF 1.509
Shen Zhenzhong,Fan Yongxian,Li Fuge,Chen Xiaolong,Shen Yinchu
Compounds with maleimide, both natural and synthesized, have good biological activities, especially the antifungal activity. In order to investigate the antifungal activity of dimethylmaleimides, 17 N -substituted dimethylmaleimides were prepared from the reactions of 2,3-dimethyl maleic anhydride and amines using a facile synthetic method in this paper. These compounds were evaluated for antifungal activities against Sclerotinia sclerotiorum by the mycelium growth rate method. They exhibited minimum inhibitory concentrations (MICs) ranging from 0.01–50.0 μg/mL, with N -(2-benzimidazole)-3,4-dimethylmaleimide being the most active one with an MIC of 0.01 μg/mL. The structure and activity relationship on these compounds indicated that the hydrophobicity of the N -substituents is associated with their antifungal activity. Compared to current antifungals, most of N -substituted dimethylmaleimides have a perfect activity for S. sclerotiorum control and low toxicity.
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COMBUSTION AND FLAME
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2012
·
IF 3.585
Olivier Herbinet,Benoit Husson,Zeynep Serinyel,Maximilien Cord,Valérie Warth,René Fournet,Pierre-Alexandre Glaude,Baptiste Sirjean,Frédérique Battin-Leclerc,Zhandong Wang,Mingfeng Xie,Zhanjun Cheng,Fei Qi
The low-temperature oxidation of n -heptane, one of the reference species for the octane rating of gasoline, was investigated using a jet-stirred reactor and two methods of analysis: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) with direct sampling through a molecular jet. The second method allowed the identification of products, such as molecules with hydroperoxy functions, that are not stable enough to be detected using gas chromatography. Mole fractions of the reactants and reaction products were measured as a function of temperature (500–1100 K), at a residence time of 2 s, at a pressure of 800 Torr (1.06 bar) and under stoichiometric conditions. The fuel was diluted in an inert gas (fuel inlet mole fraction of 0.005). Attention was paid to the formation of reaction products involved in the low-temperature oxidation of n -heptane, such as olefins , cyclic ethers, aldehydes, ketones, species with two carbonyl groups (diones), and ketohydroperoxides. Diones and ketohydroperoxides are important intermediates in the low-temperature oxidation of n -alkanes, but their formation have rarely been reported. Significant amounts of organic acids (acetic and propanoic acids) were also observed at low temperatures. The comparison of experimental data and profiles computed using an automatically generated detailed kinetic model is satisfactory overall. A route for the formation of acetic and propanoic acids was proposed. Quantum calculations were performed to refine the consumption routes of ketohydroperoxides toward diones.
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PubMed
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JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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2012
·
IF 2.947
Xing Li,Jijuan Su,Honghong Chang,Gong Li,Yanwei Li,Wenlong Wei
A simple and efficient method has been developed which describes KOH-oriented catalytic regioselective ring-opening reactions of various N -tosylaziridines with malonates. In the presence of 20 mol% KOH, most N -tosylaziridines can smoothly react with malonates to give the corresponding products in good to excellent yields (up to 99%) and with good to excellent regioselectivity under mild experimental conditions.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2012
·
IF 2.353
Xinghong Zhang,Yang Hou,Ping Hu,Changqing Hong
This paper has systematically investigated the dispersion behavior of ZrB 2 nanopowders in n-butanol solution and the adsorption mechanism of gallic acid on ZrB 2 . Gallic acid was found to be effective as a dispersant, which could provide stabilization of ZrB 2 particles in the suspension. The stability of ZrB 2 suspension and the adsorption amount of gallic acid were increased with increasing of gallic acid content (up to 6 wt%), and the pH value did not need to be adjusted. The results of Fourier transform infrared spectroscopy (FTIR) measurement and computer simulation revealed that the adsorption of gallic acid involved the interaction of two adjacent OH groups with Zr ions on the particle surfaces and complexation, which formed mononuclear chelate through a Zr atom binding to O atoms at position 3 and 4, or binuclear chelate by two Zr atoms replacing H atoms at position 4 and 5.
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Soft Matter
·
2011
·Vol. 7
·期 14
·6451-6456
·
IF 4.457
Shengtong Sun,Peiyi Wu
Near infrared spectroscopy in combination with two-dimensional correlation spectroscopy (2Dcos) and perturbation correlation moving window (PCMW) technique is employed to illustrate the gelation microdynamic mechanism of hydrogelator N-octyl-D-gluconamide (8-GA), which can rapidly self-agglomerate into helical bilayer micellar fibers upon cooling from spherical micelles. Boltzmann fitting and PCMW easily determined the gelation temperature to be ca. 72 °C and the transition temperature range to be 70–75 °C. Moreover, band shifting and splitting phenomena can be observed for CH-related overtones, indicating the formation of much ordered and tight hydrophobic core from octyl tails. On the other hand, 2Dcos was used to discern the sequential orders during the gelation process and concluded that all the group motions have a continuous transfer from the octyl tail to the chiral carbohydrate head followed by the final immobilization of the solvent, which meanwhile, is actually a continuous dehydration process from the hydrophobic core to the outer hydrophilic chiral head. The driving force of the gelation process in microdynamics can only be the dehydration process of hydrophobic octyl chains, but with final helical superstructures being stabilized by amide-associated hydrogen bonding and the “chiral bilayer effect” of carbohydrate heads.
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高影响因子
LANGMUIR
·
2011
·
IF 4.269
Lijuan Shi,Na Li,Han Yan,Yan’an Gao,Liqiang Zheng
The aggregation behavior of three long-chain N-aryl imidazolium ionic liquids (ILs), 1-(2,4,6-trimethylphenyl)-3-alkylimidazolium bromide [Cnpim]Br (n = 10, 12, and 14), in aqueous solutions was systematically explored by surface tension, electrical conductivity, and 1H NMR. A lower critical micelle concentration (cmc) for the N-aryl imidazolium ILs is observed compared with that for 1,3-dialkylimidazolium ILs [Cnmim]Br, indicating that the incorporation of the 2,4,6-trimethylphenyl group into a headgroup favors micellization. The enhanced π−π interactions among the adjacent 2,4,6-trimethylphenyl groups weaken the steric hindrance of headgroups and thus lead to a dense arrangement of [Cnpim]Br molecules at the air−water interface. An analysis of the 1H NMR spectra revealed that the introduced 2,4,6-trimethylphenyl group may slightly bend into the hydrophobic regions upon micellization. The micelle formation process for [Cnpim]Br (n = 10, 12, and 14) was found to be enthalpy-driven in the investigated temperature range, which is attributed to the strong electrostatic self-repulsion of the headgroups and the counterions as well as the π−π interactions among headgroups. Strong, stable fluorescence properties are presented by the new N-aryl imidazolium ILs, indicating their potential application in the field of photochemistry.
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C-Journal of Carbon Research
·
2024
·Vol. 10
·期 3
·62
·
IF 3.9
Xuexin Yuan,Qiqi Zhou,Yu Chen,Hai-Jian Yang,Qingqing Jiang,Juncheng Hu,Cun-Yue Guo
In the present work, inexpensive and commercially available diethyltriamine pentaacetic acid (DTPA) was used as an initiator to catalyze the N-formylation reaction of CO2with amines via the construction of C-N bonds in the presence of xanthone as the photosensitizer and PhSiH3as the reducing agent. After a systematic study of various factors, the optimal conditions for the photocatalytic reaction were obtained: 2.5 mmol of amine, 2.5 mmol of PhSiH3, 10 mol% of DTPA, 20 mol% of xanthone, 1 mL of dimethylsulfoxide (DMSO), atmospheric pressure, and 35 W UV lamp irradiation for 48 h. Under the optimal conditions, the catalyst system afforded high performance for the N-formylation of amines (primary and secondary amines) and CO2, and the yields of the N-formylated products of dialkylamines were above 70%. Further studies exhibit that the catalytic system has a wide scope of substrate applications. For various alicyclic secondary amines, heterocyclic secondary amines, aliphatic primary amines, and aromatic primary amines, the corresponding N-formylation products can be obtained efficiently. In addition, the catalyst can be recycled by simple precipitation and filtration. After five cycles of recycling, there was no significant change in the catalytic and structural properties of DTPA. Finally, a possible reaction mechanism is proposed.
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Materials
·
2024
·Vol. 17
·期 7
·1570
·
IF 3.1
Luchao Yan,Yang Wang,Shijian Lu,Zhipeng Zhu,Lingling Xu
With the fast development of the cold chain transportation industry, the traditional refrigeration method results in significant energy consumption. To address the national call for energy saving and emission reduction, the search for a new type of energy storage material has already become a future development trend. According to the national standard GB/T28577 for the classification and basic requirements of cold chain logistics, the temperature in frozen logistics is typically below −18 °C. In this study, n-undecane with a phase change temperature of −26 °C is chosen as the core material of microcapsules. Poly(methyl methacrylate) is applied as the shell material, with n-undecane microcapsules being prepared through suspension polymerization for phase change cold storage materials (MEPCM). Using characterization techniques including SEM, DSC, FTIR, and laser particle size analysis, the effects of three types of emulsifiers (SMA, Tween-80, Tween-80/span-80 (70/30)), SMA emulsifier dosage, core–shell ratio, and emulsification rate on the thermal performance and micro-surface morphology of n-undecane/PMMA microcapsules were studied. The results indicate that when comparing SMA, Tween-80, and Tween-80/span-80 (70/30) as emulsifiers, the dodecane/PMMA microcapsules prepared with SMA emulsifier exhibit superior thermal performance and micro-surface morphology, possessing a complete core–shell structure. The optimal microstructure and the highest enthalpy of phase change, measuring 120.3 kJ/kg, are achieved when SMA is used as the emulsifier with a quantity of 7%, a core-to-wall ratio of 2.5:1, and an emulsification speed of 2000 rpm. After 200 hot and cold cycles, the enthalpy of phase change decreased by only 18.6 kJ/kg, indicating the MEPCM thermal performance and cycle life. In addition, these optimized microcapsules exhibit favorable microstructure, uniform particle size, and efficient energy storage, making them an excellent choice for the refrigeration and freezing sectors.
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