JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2014
·Vol. 117
·期 2
·603-610
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IF 2.206
Liu Jialin,Li Jingrui,Fan Mengjin,Zhang Junying,Cheng Jue
Aromatic amine curing agent with flexible unit in backbone, 1,4-bis (4-diaminobenzene-1-oxygen) n -butane (DDBE), was synthesized, and the structure was confirmed by FT-IR and 1 H NMR. The curing kinetics of tetraglycidyl methylene dianiline (TGDDM, or AG80) using DDBE and 4,4′-bis-(diaminodiphenyl) methane (DDM) as curing agents, respectively, were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TG, respectively. The results showed that the activation energy of AG80/DDBE system was slightly higher than that of AG80/DDM system. Šesták-Berggren model can generally simulate well the reaction rates of these two systems. DMTA measurements showed that the storage modulus of cured AG80/DDBE is similar to that of cured AG80/DDM at the temperature below glass transition temperature ( T
g ) and lower than that of cured AG80/DDM at the temperature above glass transition temperature, while T
g of cured AG80/DDBE is lower than that of cured AG80/DDM. TG showed that the thermal stabilities of these two cured systems are similar.
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CHEMICAL ENGINEERING SCIENCE
·
2015
·
IF 2.337
Jun Mei,Jianyong Mao,Zhirong Chen,Shenfeng Yuan,Haoran Li,Hong Yin
The aim of this paper is to explore the reason for the catalyst-free phenomenon of synthesizing 4-hydroxy-2-butanone from formaldehyde and acetone under supercritical conditions and in high-temperature liquid-phase. Experiments were conducted in a tubular flow-type reactor at temperatures between 230 and 270 °C for residence times between 0.5 and 8 min. Under these conditions, a small amount of formic acid appeared via noncatalytic self-disproportionation of formaldehyde. The generated formic acid proved to play a role as catalyst in main reactions. A mechanism-based detailed chemical kinetics model for main reactions was suggested to assess the effect of temperature. This model applied well both under supercritical conditions and in high-temperature liquid-phase. The activation energies for forming and dehydration of 4-hydroxy-2-butanone were 97.5±3.5 kJ/mol and 120.6±5.8 kJ/mol, respectively.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2015
·
IF 3.091
Lixin Xing,Ningning Guo,Yatao Zhang,Haoqin Zhang,Jindun Liu
Silica spheres in nanoscale were prepared via sol–gel method and then sodium 4-styrene sulfonate was grafted onto the surfaces of SiO 2 (PSS-SiO 2 ) by surface-initiated atom transfer radical polymerization (SI-ATRP). Then, a negatively charged loose SiO 2 -PSS/polyethersulfone (PES) nanofiltration membrane with high flux was fabricated via phase inversion method. FT-IR and TEM results showed that SiO 2 nanoparticles were synthesized and modified successfully. GPC results further proved the “living”/controlled behavior of SI-ATRP. The morphology, hydrophilicity of the membranes were investigated by SEM, static water contact angle and water ratio. The results revealed that the surface hydrophilicity and water permeability of hybrid membranes were greatly improved after adding SiO 2 -PSS and thus may enhance fouling resistance to a certain extent. The salt permeation and separation of dye/salt mixture of the hybrid membranes were significantly superior to the pure PES membrane, and the order of permeation for different salt solutions was NaCl > MgCl 2 > MgSO 4 > Na 2 SO 4 . When the content of SiO 2 -PSS was 3.0 wt%, the hybrid membrane showed optimal performance with IEC value of 0.07 mmol/g and pure water flux of 269.5 L m −2 h −1 and the rejections for all types of salts declined to under 11%. The above results indicated that SiO 2 -PSS incorporated into PES matrix played an important role in enhancing the performance of NF membranes, which may possess a significant impact on the application in dye purification and desalination.
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ANALYTICAL CHEMISTRY
·
2015
·
IF 5.636
Lei Yu,Jun Ding,Ya-Lan Wang,Ping Liu,Yu-Qi Feng
Monitoring brassinosteroids (BRs) has been of major interest of researchers as these substances play a crucial role in a variety of phytological processes in plants. However, the determination of endogenous BRs in plant tissue is still a challenging task due to their low abundance and the complex matrix of plant tissues. In this study, a single step strategy by combining tip extraction and in situ derivatization was proposed for BR analysis. In the proposed strategy, a mixed mode sorbent (C8-SO3H) in tip was modified with 4-phenylaminomethyl-benzeneboric acid (4-PAMBA) through cation exchange and hydrophobic interactions, and then used as a boronate affinity media to selectively capture and purify BRs from plant extract through the reaction of boric acid groups of 4-PAMBA and cis-diol on BRs. The BRs-4-PAMBA derivatives formed were easily eluted from the C8-SO3H tip by nullifying the ion exchange and hydrophobic interactions using ammonia acetonitrile, followed by LC-MS/MS analysis. BR standards, isotopically labeled with d5-4-phenylaminomethyl-benzeneboric acid (4-PAMBA-d5) were introduced to improve the assay precision of LC-MS/MS. Under the optimized conditions, the overall process could be completed within 1 h, which is greatly improved in speed compared with previously reported protocols. In addition, the detection sensitivities of labeled BRs were improved by over 2000-fold compared with unlabeled BRs, thus the consumption of plant materials was reduced to 50 mg. Finally, the proposed method was applied for the investigation of BRs response in rice toward Cd stress.
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CHEMISTRY OF MATERIALS
·
2017
·
IF 9.466
Bin-Wen Liu,Min-Yi Zhang,Xiao-Ming Jiang,Shu-Fang Li,Hui-Yi Zeng,Guo-Qiang Wang,Yu-Hang Fan,Yong-Fei Su,Chunsen Li,Guo-Cong Guo,Jin-Shun Huang
Two new polar polyselenides Rb4Ge4Se12 (1) and Cs4Ge4Se12 (2) with rarely reported dimeric [Ge2Se4(μ-Se2)]4– units were synthesized. They present large second-harmonic generation (SHG) intensities of 7.5 and 6.5 times that of the benchmark AgGaS2 with type I phase-matching behavior, high laser-induced damaged thresholds, a wide transmission region and congruently melting behavior, making them excellent candidates for IR nonlinear optical (NLO) applications. The SHG functional motifs of both compounds are determined to be [Ge2Se4(μ-Se2)]4– unit by time-dependent density functional theory calculation, which further reveals that charge transfers from the lone pairs of terminal Se atoms to the five σ* orbitals of five-membered ring Ge2Se3 have a predominant contribution to the total SHG effect.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2016
·
IF 8.328
Haiping Li,Tingxia Hu,Renjie Zhang,Jianqiang Liu,Wanguo Hou
Up to now, studies on solid-state Z-scheme two-component heterojunctions have hardly referred to roles of interfacial internal electric fields (IEFs). Herein, solid-state Z-scheme Bi 2 MoO 6 /MO (M = Cu, Co 3/4 , or Ni) heterojunction photocatalysts were simply synthesized, for the first time, with enhanced photocatalytic performance toward organic degradation. Electron microscopy images reveal that the MO homogeneously distributes on surfaces of the Bi 2 MoO 6 hierarchical microspheres, and they close contact with distinct heterojunction interfaces. X-ray photoelectron spectra (XPS) suggest that the electron transfer occurs between the Bi 2 MoO 6 and MO after they contact, resulting in formation of IEFs at their interfaces. Based on band gap values and valance-band XPS and ultraviolet photoelectron spectra, energy band levels of the Bi 2 MoO 6 and MO are defined, and directions of the interfacial IEFs are determined. The IEFs play key roles for the formation of the Z-scheme Bi 2 MoO 6 /MO heterojunctions and for the photoactivity enhancement. This work provides a better insight into the formation mechanism of solid-state two-component Z-scheme heterojunctions and a significant experimental guidance for studying other similar systems.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2016
·
IF 1.835
Jianfeng Hao,Wenge Yang,Hongjie Li,Shimin Fan,Wangdan Zhao,Yonghong Hu
We focus on the solubility of 4-methylsulfonylacetophenone. A gravimetric method was taken to measure the solubility of 4-methylsulfonylacetophenone in n-hexane, ethyl acetate, methanol, ethanol, n-propyl alcohol, n-butyl alcohol, ethylene glycol, cyclohexane, isobutyl alcohol, and (ethyl acetate + n-hexane) binary solvent mixtures from 278.15 K to 328.15 K under atmospheric pressure. Its corresponding (solid + liquid) equilibrium results will provide essential support for further theoretical studies. The solubility of 4-methylsulfonylacetophenone in nine pure solvents were correlated with λh and Apelblat models, while 4-methylsulfonylacetophenone in (ethyl acetate + n-hexane) binary solvent mixtures were correlated with the Apelblat and CNIBS/R–K models. The Apelblat model was proven to be the best-fit model for correlating the solubility of both pure solvents and binary solvents mixtures from the analysis of the STATISTIC.
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FLUID PHASE EQUILIBRIA
·
2016
·
IF 1.846
Ke Bei,Chuanyong Zhang,Junliang Wang,Kai Li,Jinghui Lyu,Jia Zhao,Jie Chen,I-Ming Chou,Zhiyan Pan
The solubility of 4-chlorotoluene in subcritical water was measured using an optically transparent fused silica capillary reactor (FSCR). The total dissolution temperature of 4-chlorotoluene in subcritical water was visually determined. The dissolution uniformity of 4-chlorotoluene in subcritical water was confirmed by Raman spectroscopy. The solubility of 4-chlorotoluene linearly increased with increasing temperature in the range 262.3–293.8 °C. The dissolution mechanism of 4-chlorotoluene in subcritical water is proposed based on the Raman spectra of 4-chlorotoluene and water during the dissolution process in the FSCR.
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RSC Advances
·
2016
·Vol. 6
·期 58
·53080-53088
·
IF 3.289
Jie Liu,Zhiwei Zhao,Zhaoxia Ding,Zhendong Fang,Fuyi Cui
Magnetic Au–Fe3O4 nanocomposites with various Au weight loading were synthesized through a one step strategy. The morphology and physicochemical properties of the as-synthesized solids were characterized through various methods. After that, the catalysts were applied to activate H2O2 for the degradation of 4-chlorophenol (4-CP). The results showed that Au–Fe3O4 can catalyze oxidation of 4-CP efficiently in the presence of H2O2 at pH 5, which may be attributed to the synergistic catalysis in the nanocomposites for hydroxyl radical generation. And then, the influence of reaction parameters on the oxidation of 4-CP, including the Au weight loading of the nanocomposites, pH, catalyst dosage, H2O2 dosage and temperature, were assessed. The stabilization and reusability of the Au–Fe3O4 nanocomposites was shown to be excellent, with no leakage of Au. The hydroxyl radicals (˙OH) were the main reactive radicals released in the Au–Fe3O4/H2O2 system according to the addition of tert-butanol and the spin-trapping electron paramagnetic resonance (EPR) by means of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), while the ˙OH in the bulk solution acted in the main role for 4-CP degradation. Finally, the mechanism of H2O2 activated with Au–Fe3O4 for 4-CP degradation was proposed.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Lin Lin,Chunchao Hou,Xuehua Zhang,Yanjie Wang,Yong Chen,Tao He
Photocatalytic reduction of CO 2 into value-added chemicals is particularly attractive as it could produce renewable energy and capture greenhouse gas. Photoreduction of CO 2 can be realized over molecular and inorganic catalysts. The former usually exhibit high activity, but low stability and often inactive under visible-light irradiation; the latter has low activity, but good stability. Here we use g-C 3 N 4 nanosheets as the photosensitizer to integrate with Fe tetra(4-carboxylphenyl)porphyrin chloride (FeTCPP) molecular catalyst. Besides π-π stacking between tri- s -triazine unit and porphyrin , the carboxyl group modified Fe porphyrin is used for the first time in CO 2 photoreduction so as to form hydrogen bonding with the rich amino groups in g-C 3 N 4 nanosheets. g-C 3 N 4 /FeTCPP heterogeneous catalysts are prepared via a facile self-assembly approach, in which light harvest is separated from catalysis spatially and temporally. The obtained g-C 3 N 4 /FeTCPP heterogeneous catalysts exhibit high activity for CO 2 reduction under visible-light irradiation, with CO yield of 6.52 mmol g −1 in 6 h and selectivity up to 98%. Fluorescence data indicate that the electrons can efficiently transfer from the g-C 3 N 4 nanosheets to FeTCPP. The mechanism for CO 2 reduction over the g-C 3 N 4 /FeTCPP heterogeneous catalysts is proposed based on the results of quasi in-situ ESR and UV–vis measurements. This work may pave a facile approach for fabricating the high-efficient photocatalysts for CO 2 reduction, as well as better understanding the related mechanism.
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CELLULAR SIGNALLING
·
2024
·
IF 4.4
Wentao Hu,Menghan Wang,Guifang Sun,Limin Zhang,Hong Lu
Parkinson's disease (PD) is a gradually debilitating neurodegenerative syndrome. Here, we analyzed GSE7621 chip data obtained from the Gene Expression Omnibus (GEO) database to explore the pathogenesis of PD. Early B Cell Factor 3 (EBF3), a member of the highly evolutionarily conserved EBF-transcription factor family, is involved in neuronal development. EBF3 expression is low in the substantia nigra of patients with PD. However, whether EBF3 is implicated in dopaminergic neuron death during PD has not yet been investigated. Therefore, we aimed to reveal the potential anti-apoptotic effect and molecular mechanism of EBF3 in PD. We established a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model in vivo and a 1-methyl-4-phenylpyridine (MPP + )-induced SH-SY5Y cell model in vitro . EBF3 was downregulated in the substantia nigra of PD mice and SH-SY5Y cells treated with MPP + , and the m6A methylation modification level was low. Fat mass and obesity-associated protein (FTO) siRNA upregulated m6A methylation modification of EBF3 and extended the EBF3 mRNA half-life. Functionally, as demonstrated by the results of the open-field test, pole test and gait analysis, EBF3 overexpression ameliorated MPTP-induced behavioral disorder. Further, EBF3 overexpression suppressed neuronal apoptosis in vivo , as evidenced by decreased TUNEL + cells, and the increased activation of caspase-3 and caspase-9. Similar results were obtained in vitro , as reflected by increased cell viability, decreased LDH activity and restored mitochondrial function, collectively protecting SH-SY5Y cells from MPP + -induced apoptosis. Mechanistically, the results of luciferase reporter, ch-IP and DNA pull-down assays confirmed that, as a transcription factor, EBF3 bound to the promoter of CNTNAP4 (a protein associated with neuronal differentiation) and directly regulated CNTNAP4 transcription. Strikingly, CNTNAP4 knockdown markedly abolished the effect of EBF3 on cell apoptosis, thus aggravating PD. In conclusion, the low level of m6A methylation modification may contribute to the low expression of EBF3 during PD. Additionally, EBF3 attenuates PD by activating CNTNAP4 transcription, suggesting that EBF3 may be a novel therapeutic target in PD.
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JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Yanrong Cheng,Chunyang Liu,Xia Guo
An aqueous two-phase system (ATPS) has been considered a green separation system. How to improve the separation efficiency and selectivity of ATPS has always been a widely concerned issue. However, so far, the construction of selective ATPS still remains a challenging task. Calixarenes are the third generation of supramolecular compounds. They exhibit significant advantages in recognizing small molecules. In the present study, calixarene was used for the first time to prepare selective ATPSs, which are sulfonatocalix[4]arene (SC[4])/1-decyl (or hexyl)-3-methylimidazolium bromide ([C n mim]Br)/trisodium citrate (Na 3 C 6 H 5 O 7 ) ATPS and SC[4]/1-decyl-3-methylimidazolium bromide ([C 10 mim]Br) ATPS. Ten aromatic molecules, including theobromine, syringic acid, vanillin, vanillic acid, theophylline, cephalexin, L-tyrosine, L-phenylalanine, S-mandelic acid, and L-tryptophan, were selected as model extracts to evaluate the selectivity of these SC[4]-based ATPSs. The results showed that among these 10 extracts, the SC[4]/[C n mim]Br/Na 3 C 6 H 5 O 7 ATPS has high selectivity toward vanillin, and the SC[4]/[C 10 mim]Br ATPS has high selectivity toward L-phenylalanine. Specifically, in the SC[4]/[C n mim]Br/Na 3 C 6 H 5 O 7 ATPS, the partition coefficient of vanillin can reach 315.7, while the partition coefficients of the other 9 extracts are around 2.4–23.1 In the SC[4]/[C 10 mim]Br ATPS, the partition coefficient of L-phenylalanine is much higher than 1 (i.e., 4.38–5.55), while the partition coefficients of the other extracts are below or around 1. The 1 H NMR spectra and response surface plots based on the Box-Behnken design further demonstrate the role of [C n mim]Br-SC[4] complex in the selectivity of these ATPSs.
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