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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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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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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MICROPOROUS AND MESOPOROUS MATERIALS
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2017
·
IF 3.615
Zhihong Tian,Jiajia Huang,Xin Zhang,Gonglei Shao,Qiuyun He,Shaokui Cao,Siguo Yuan
High adsorption capacity and selectivity of microprous carbon are critical for exceptional post-combustion CO 2 capture ability. Herein we report a novel strategy to prepare N-doped microprous carbon with high surface area (2363 m 2 g −1 for CPTHB-7), narrow pore size distribution and high ultramicropore ratio (<0.7 nm, 68% for CPTHB-6) via a simple chemical activation of a rigid polymer porous framework (PTHB) synthesized via polycondensation reaction of 1,3,5-THB and aniline. The as-prepared microprous carbon exhibit high CO 2 adsorption capacities of 5.6–6.3 mmol g −1 (273 K and 1 bar) and sufficient CO 2 /N 2 selectivity of 12–22 for a 0.15/0.85 CO 2 /N 2 mixture at 298 K and 1 bar (conditions of CO 2 capture application). The effect of microporosity and N content for our materials on the CO 2 adsorption performance had also been investigated. Microporous volume below critical size contributed to the adsorption capacity for CO 2 , while the N content and nitrogen species play a role in the CO 2 /N 2 selectivity.
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RSC Advances
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2017
·Vol. 7
·期 36
·22071-22078
·
IF 3.108
Cejun Hu,Guoxin Zhang,Haoyuan Li,Cong Zhang,Yingna Chang,Zheng Chang,Xiaoming Sun
Compositing graphene oxide (GO) with controllable secondary components is of great significance to achieve carbon materials with high-level physicochemical properties. In this study, thin sandwich composites of GO and N-doped carbon (GO@NdC) were fabricated through controllable deposition of polyvinyl dichloride (PVDC)-dehalogenated carbon on GO; this method exploited the high affinity between PVDC and GO. The thin deposited carbon layers on GO achieved the thicknesses ranging from 1.0 to 2.0 nm. Considering that dehalogenated carbon has been verified to be highly reactive for coupling heteroelements, an overall N content of ∼7.0 at% was obtained with the addition of melamine as a N source. Moreover, the byproducts EtOH and NaCl could tune the composites into open 3D structures in situ, efficiently preventing the thin-layered composites from re-stacking. After activation with KOH, GO@NdC further demonstrated a hierarchical pore structure and large specific surface area. Remarkably, KOH-activated GO@NdC exhibited a high specific capacitance of ∼354 F g−1 and a capacitance retention of >65% (at 10.0 A g−1). Finally, the GO@NdC symmetric supercapacitor also achieved a high specific energy of ∼11.8 W h kg−1 in an aqueous alkaline electrolyte.
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ENZYME AND MICROBIAL TECHNOLOGY
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2016
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IF 2.624
Jian Qin Zhou,Ting He,Jian Wen Wang
Microbial transglutaminase (mTG) is widely utilized in the PEGylation of pharmaceutical proteins. mTG immobilization can be achieved via covalent bonding on solid supports. However, the catalytic efficiency of mTG immobilized on solid supports was significantly reduced by mass transfer limitation. To overcome this limitation, mTG was covalently immobilized on the thermo-responsive carboxylated poly( N -isopropylacrylamide) (pNIPAM). The pNIPAM-mTG conjugate exhibited reversibly solubility in aqueous solution with a low critical solution temperature (LCST) at 39 °C, i.e., it was insoluble above 39 °C and soluble below 39 °C. The pH dependence of the pNIPAM-mTG conjugate was similar with that of the native mTG. Upon conjugation to pNIPAM, the optimal temperature of mTG shifted down from 50–55 °C to 40–45 °C, and the thermal stability of the conjugate was elevated. The easy separation of the pNIPAM-mTG conjugate with its substrate and the catalytic efficiency of the pNIPAM-mTG conjugate were demonstrated by employing the pNIPAM-mTG conjugate to cross-link bovine serum albumin (BSA) and catalyze PEGylation of therapeutic protein, cytochrome c (Cyt C), respectively. The thermo-responsive mTG is suitable to modify proteins in food processing and biomedical engineering.
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Science China-Chemistry
·
2017
·Vol. 60
·期 9
·1191-1196
·
IF 4.132
Ji Shaobo,El Mard Hicham,Smet Mario,Dehaen Wim,Xu Huaping
Macrocycles possess potential applications in supramolecular chemistry and biosystems. Thus development of new kinds of macrocycles is of significance. Herein, novel macrocycles containing Se–Se/Se–S bonds were synthesized via transformation between selenium related dynamic covalent bonds. A monomer containing two ebselen moieties was synthesized ( M1 ). The Se–N bonds in M1 were reduced by dithiothreitol, forming Se–S linked dimer ( D1 ). To realize the transformation from Se–S bonds to Se–Se bonds, guest molecules were added as template, triggering the formation of Se–Se linked dimer ( D2 ). The formation of these two new kinds of macrocycles was determined by 1 H NMR and 77 Se NMR, and the necessity of guest molecules was also confirmed. The introduction of ebselen moieties and Se–S bonds or Se–Se bonds into macrocycles may endow it with new responsiveness and bioactivities, as well as new types of host-guest chemistry.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2017
·
IF 4.9
Jirui Yang,Feng Shen,Mo Qiu,Xinhua Qi
This paper reports a nonreductive dechlorination pathway (dehydrochlorination) of lindane in the presence of N -MWCNTs (CNT-N1 and CNT N2) under environmentally relevant conditions. The enhanced catalytic dehydrochlorination at mild pH values (7.0–9.0) was mainly attributed to the Lewis base nature of nitrogen functional groups on the surface of N -MWCNTs, based on FT-IR spectra, X-ray photoelectron spectroscopy and CO 2 -TPD profile. Amine and pyridinic nitrogen species were inferred as the main basic sites that were responsible for the dehydrochlorination of lindane. The concentration of lindane was unchanged in homogenous alkaline aqueous solutions at pH 7.0 and 8.0 within 6 d, and up to 89.5% of lindane remained at pH 9.0. In sharp contrast, the reaction rate constant ( k obs ) increased from 0.024 to 0.876 d − 1 with the increasing pH from 7.0 to 9.0 when CNT-N2 catalyst was used. All lindane was transformed in the presence of CNT-N2 at pH 9.0, leading to a much greater k obs as compared to that obtained in homogenous solution (0.876 vs 0.019 d − 1 ). Even at neutral pH condition, the k obs obtained in the presence of CNT-N2 was higher than that observed in weakly alkaline solution (0.024 d − 1 at pH 7.0 vs 0.019 d − 1 at pH 9.0). γ-1,3,4,5,6-pentachlorocyclohexene and trichlorobenzene isomers were detected as the intermediate and final products, respectively. It might be inferred that amine and pyridinic nitrogen species could attack the hydrogen atom attached to the β‑carbon, and the dehydrochlorination of lindane followed a β-elimination mechanism. This study provides an alternative dechlorination way for making lindane less toxic and better biodegradable under mild conditions, which is beneficial for complete mineralization of lindane when coupled with microbial degradation.
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HIGH PERFORMANCE POLYMERS
·
2014
·
IF 1.09
Yewei Xu,Yi Sun,Yonglin Lei,Jichuan Huo,Lin Zhang
Poly(N-arylenebenzimidazole ketone ketone pyridine)s have been prepared via N–C coupling reaction that removed the N–H sites from the novel bis(benzimidazoyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and elemental analysis. All resulting polymers showed essentially amorphous patterns. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>179°C), good thermostability, and high decomposition temperatures (>401°C). These novel polymers also showed easy solubility.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2013
·
IF 3.172
Zhihua Fu,Na Zhang,Jie Liu,Tiesheng Li,Wenjian Xu,Fei Wang,Tao Wang,Zhen Zhai,Linlin Liu,Luyan Mao,Yangjie Wu
Poly (N-hydroxy methyl acrylamide)-grafted silicon, glass, and quartz surfaces were successfully prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) with methyl alcohol/water mixtures as solvents and CuCl/2,2-dipyridyl as a catalyst. The modified surfaces were characterized by water contact angle, atomic force microscope (AFM), Fluorescence spectrophotometer, Low-angle X-ray diffraction (LAXRD), and X-ray Photoelectron Spectroscopy (XPS). The results showed that the homogeneous and well hydrophilic N-hydroxymethyl acrylamide polymer brushes (NHAM-brushes), which had high hydrophilic properties and the added advantage of providing 3-D coatings with higher binding capacities, were obtained successfully. Cyclopalladated arylimine functionalized polymer brushes were also obtained by reacting HAM-brushes with N,N′-Carbonyldiimidazole (CDI) and cyclopalladated arylimine. The catalyst functionalized PHAM-brushes had good catalytic activity in heterogeneous compared to homogeneous catalyst and exhibited much improved stability and recyclability over time in Suzuki cross-coupling reaction.
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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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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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