JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2018
·
IF 3.468
Xiqing Wang,Miaojun Xu,Zhiyong Zhang,Yang Leng,Bin Li
A novel N -alkoxyamine containing compound 2,4,6-tri-(1-cyclohexyloxy-4-imino-2,2,6,6-tetramethylpiperidine)-1,3,5-triazine defined as T-TEMPOC was synthesized. Its chemical structure was well characterized and confirmed. The synthesized T-TEMPOC was incorporated into polypropylene (PP) to preparing flame retardant PP film (NOR-PP film). The NOR-PP film with the thickness of 0.2 mm successfully passed UL-94 VTM-0 rating during vertical burning test and its limiting oxygen index value reached 27.3% when 2.0 wt% T-TEMPOC was incorporated, and the heat release rate and total heat release were decreased obviously. The incorporation of T-TEMPOC inhibited the initial thermal degradation of PP on heating and then enhanced the thermal stability of PP film. The NOR-PP film maintained excellent mechanical performance with the introduction of T-TEMPOC. T-TEMPOC could decompose and generate nitroxyl radical, which confirmed by pyrolysis gas chromatography mass spectra measurement. The nitroxyl radical could quench the active free radicals to block the radical chain reaction during combustion, thus suppressed and even extinguished the flame. Moreover, nitroxyl radical was regenerated under the existing of the peroxide. The cyclic process of nitroxyl radical quenching active free radicals and self-regeneration were constructed, which was critical for improving the flame retardant efficiency for PP film. The results might have a promising prospect for flame retardant polymer film.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
Inorganic and Nano-Metal Chemistry
·
2021
·
IF 1.716
Jiahua Guo,Yuqi Zhang,Shouwen Jin,Xiaoyun Ye,Kaikai Hu,Weiqiang Xu,Daqi Wang
Eight organic-inorganic hybrid salts [(HL1)(SbCl4)] (1) (L1 = N,N-dimethylbenzylamine), [(HL2)2(ZnCl4)] (2) (L2 = 4-chlorobenzylamine), [(HL2)(L2)(CuCl3)(H2O)2] (3), [(HL3)2(Sb2OCl6)] (4) (L3 = quinoline), [(HL4)4(Bi2Cl10)] (5) (L4 = 2-methylquinoline), [(HL5)(SbCl4)] (6) (L5 = 5,7-dimethyl-1,8-naphthyridine-2-amine), [(H2L6)(SbCl5)] (7) (L6 = 3,6-bis(imidazol-1-yl)pyridazine) and [(H2L7)2(CuBr4)2] · 7H2O (8) (L7 = di(2-benzimidazol-1-ylethyl)ether) were prepared and characterized by IR, XRD, EA and TG analysis. XRD analysis told that all of the complexes were 3 D net built from non-covalent bonds from the cations and the halometallates. The aryl rings of the cations in all of the compounds are essentially planar. The H2O also had crucial role in structure extension in 3 and 8. Extensive intermolecular interactions have been used in the self-assembly of diverse motifs, ranging from strong N-H···X (X = Br, Cl), N-H···O, N-H···N, O-H···O, O-H···Br H-bonds to weak CH2···O, CH3-Cl/CH2-Cl/CH-Cl, Cl-Cl, O-Br, CH3-π, CH2-π, Cl-π and π-π associations. The arrangements of the anions and cations in the solid are ruled not only by the size and symmetry of the cations, but also by the non-covalent bonds in the crystal structures.
研究领域:
无机化学
·
材料科学
✓ 已验证
DOI
高影响因子
ChemSusChem
·
2019
·Vol. 12
·期 4
·858-865
·
IF 7.804
Xinxin Li,Qingshan Zhao,Xiang Feng,Lei Pan,Zhuangzhuang Wu,Xiaocui Wu,Tianwen Ma,Jialiang Liu,Yuanyuan Pan,Yan Song,Mingbo Wu
Graphical Nitrogen-doped graphene nanoshells supporting palladium nanoparticles (Pd/N-GNS) have been developed as a superior catalyst for the N -allylation reaction. Experimental results and DFT calculations reveal strong metal–support interactions between the pyridinic N and palladium species, which significantly boost the catalytic efficiency and stability of the catalyst. In this study, nitrogen-doped graphene nanoshells (N-GNS) were developed to support palladium nanoparticles (Pd/N-GNS) as an efficient and recyclable catalyst for the N -allylation reaction. N-GNS was synthesized through a facile hard-template method by using petroleum asphalt, followed by nitrogen doping by thermal annealing with urea, the contents and species of which could be altered by the calcination temperature. Palladium nanoparticles (Pd NPs) with an average diameter of 3.3 nm were homogeneously deposited onto the N-GNS support through a mild solvent-growth approach. The Pd/N-GNS exhibited a superior activity towards the N -allylation reaction, 6-fold higher than that of the pristine graphene nanoshells supporting the palladium catalyst. The Pd/N-GNS could be recycled several times without activity deterioration and metal leaching. The catalytic activity showed a linear correlation relationship with the pyridinic N content. Experimental and theoretical studies reveal strong metal–support interactions between the pyridinic N and palladium species, which can downsize the Pd NPs, modulate the electronic properties, and promote the adsorption of reactant, thereby significantly boosting the catalytic efficiency and stability for the N -allylation process. The present work could help unravel the roles of nitrogen-doped carbon supports and provides a feasible strategy to rationally design superior palladium catalysts for chemical transformations.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Siqi Wang,Zhi Yang,Yuejun Sun,Yu Xiao,Li-Dong Zhao
PbTe-based thermoelectric materials are considered to be a medium-temperature thermoelectric candidates and the high-performance n -type PbTe is urgently to be developed to match its p -type counterpart on account of practical application. Herein, we firstly optimized the carrier density of n -type PbTe through Sb doping, and obtained a maximum ZT value of ∼1.0. Then, based on the optimized carrier density, we introduced ternary compounds AgSb(Se, Te) 2 to suppress the lattice thermal conductivity . Minimum lattice thermal conductivity of n -type PbTe was reduced as low as ∼0.53 W m −1 K −1 and ∼0.62 Wm −1 K −1 through introducing AgSbSe 2 and AgSbTe 2 , respectively. Combining the maintained electrical properties with suppressed thermal conductivity , maximum ZT values ∼1.2 and ∼1.3 were obtained in PbTe+2%AgSbSe 2 and PbTe+2%AgSbTe 2 , respectively. This work provides an effective strategy of synergistically balancing charge and phonon transports in n -type PbTe with ternary AgSb(Se, Te) 2 compounds.
研究领域:
材料科学
·
热电转换
·
凝聚态物理
·
半导体物理
·
功能材料
·
能量转换材料
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 20
·6285-6293
·
IF 6.177
Jie Lian,Qiang Bai,Jinyu Zhao,Xiaomin Wang
It is a grand challenge to develop non-noble metal-based oxygen reduction (ORR) catalysts with relatively high activity and stability for proton exchange membrane fuel cells (PEMFCs). Herein, zeolitic imidazolate framework (ZIF) precursors were grown in situ on graphene oxide (GO), and Co-N-RGO catalysts with good stability were successfully prepared. Density functional theory (DFT) calculation results show that Zn and Co are mixed and alternated to form a Zn-Co-ZIF structure instead of forming ZIF-8 or ZIF-67, separately. Such a combination promoted the uniform distribution of Co atoms in the N-doped carbon frameworks during subsequent heat treatment. By means of accurate adjustment of the molar ratio of Co/Zn species in the Zn-Co-ZIF precursors, the hierarchical porous structure connected with uniformly dispersed Co–Nx sites was established after thermal activation, and the utilization rate of active sites was improved. The RGO in catalysts, connecting each derivative carbon particle, formed a connected network and reduced the ohmic impedance of the catalyst layer. This strategy avoided the traditional tedious steps of additional acid-leaching and second heat treatments. What's more, the ORR performance of the Co-N-RGO samples was evaluated. The catalyst exhibited a positive half-wave potential (0.75 V vs. RHE), high limiting diffusion current density, and positive stability at 0.5 M H2SO4. Meanwhile, the H2/O2 fuel cell test result displayed a relatively high ORR activity with a peak power density of 334 mW cm−2.
研究领域:
能源材料
·
电化学
·
纳米材料
·
催化化学
·
燃料电池技术
✓ 已验证
DOI
高影响因子
IRANIAN POLYMER JOURNAL
·
2023
·Vol. 32
·期 9
·1189-1197
·
IF 3.1
Luo Yanrong,Lu Chunlan,Zhang Xiaolin,Zhan Shiping
With the widespread use of hydrogels, injectable hydrogels for the human body require higher safety and non-toxicity. The most important is the choice of cross-linking agent to be green. In this study, acylated chitosan macromolecular crosslinkers (MCS) were prepared by maleic acid (MA) and chitosan (CS). Its structure was confirmed by FTIR and 1 H NMR and its degree of acylation was also determined. Then, a series of polymeric network hydrogels were investigated. The cross-linked copolymer poly( N -isopropyacrylamide-maleic acid copolymer)/acylated chitosan P(NIPAM- co -MA)/MCS is a series of thermosensitive hydrogels formed by free radical polymerization of NIPAM and MA with MCS as cross-linking agent. The apparent morphology, thermosensitive transition point, and hydrophilicity were investigated. The results show that the hydrogel has a homogeneous pore structure inside. The optimal low critical solution temperature (LCST) was 36.66 ℃. In addition, with the increase of maleic acid content, the water contact angle of the hydrogel is smaller, that is, the hydrophilic effect is better. The results indicate that the P(NIPAM- co -MA)/MCS hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application. This study can provide a certain research basis and relevant theoretical basis for clinical practice. Graphical abstract
研究领域:
高分子科学
·
材料科学
·
生物医学工程
·
药物制剂技术
✓ 已验证
DOI
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Li Jiang,Yiqian Yang,Lin Huang,Yan Zhou,Junwei An,Yuchun Zheng,Yiwei Chen,Yanhong Liu,Jianhui Huang,Ee Lui Ang,Suwen Zhao,Huimin Zhao,Rongzhen Liao,Yifeng Wei,Yan Zhang
The various isomers of hydroxyproline (HP) are widely distributed in nature, serving as key components of structural proteins, while their quaternized betaine derivatives function as osmoprotectants in many organisms. Aerobic bacteria degrade HPs through a variety of well-studied mechanisms. Recent studies show that certain anaerobic bacteria degrade HPs through distinct mechanisms, involving the O2-sensitive glycyl radical enzymes (GREs) t4L-HP dehydratase (HypD) and t4D-HP C–N lyase (HplG). Here, we report the discovery of two more GREs, N-methyl c4L-HP dehydratase (HpyG) and N-methyl c4D-HP dehydratase (HpzG), which catalyze radical-mediated dehydration of the two N-methyl-c4HP enantiomers, while also displaying significant activities toward their unmethylated substrates. Both GREs are associated with homologues of pyrroline-5-carboxylate reductase, which catalyze reduction of their products N-methyl-pyrroline-5-carboxylate to form N-methyl-proline. Crystal structures of HpyG and HpzG in complex with their substrates revealed active site architectures distinct from that of HypD and provided insights into the mechanism of enantioselective radical-mediated dehydration. Our research further expands the repertoire of diverse chemical mechanisms involved in the bacterial metabolism of highly prevalent HP isomers and derivatives in the anaerobic biosphere.
研究领域:
生物化学
·
微生物学
·
酶学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
·
2016
·Vol. 54
·期 12
·1145-1151
·
IF 3.318
Yating Gao,Jinxian Yang,Haiyan Fan,Yanwei Ding,Xiaodong Ye
The effect of different functional groups of methylated urea on the phase transition of poly( N -isopropylacrylamide) (PNIPAM) aqueous solutions has been studied by a high-sensitivity differential scanning calorimetry. The results reveal that with the addition of osmolytes with N H groups, the enthalpy change increases with the number of DSC cycles, presumably due to the gradual formation of hydrogen bonds with dehydrated CO groups of PNIPAM at high temperature. Moreover, with the addition of tetramethylurea (TMU) without hydrogen bond donor groups, the enthalpy change of PNIPAM solution remains unchanged with the number of DSC cycles and decreases with the TMU concentration, suggesting that the van der Waals interactions between TMU and isopropyl groups of PNIPAM and the weakening of hydrophobic interactions between isopropyl groups play a dominant role in the effect of TMU on the phase transition of PNIPAM. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 1145–1151
研究领域:
高分子化学
·
物理化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Erbing Hua,Shu Jin,Xiaorong Wang,Shuang Ni,Gang Liu,Xiaoxiang Xu
In this work, novel 2D type-II p-n heterojunctions La 2 Ti 2 O 7 /In 2 S 3 have been fabricated. The heterojunctions exhibit much improved photocatalytic activity over individual moieties and their physical mixtures in which 18-fold increment in hydrogen production has been achieved under visible light illumination (λ ≥ 400 nm). Their superior activities stem from intimate face-to-face contact between La 2 Ti 2 O 7 and In 2 S 3 in the heterojunctions which guarantee facile charge interchange. Photoelectrochemical analysis suggests that efficient charge separations occur at the interfaces of the heterojunctions and contributes to a prolonged charge lifetime as well as the much enhanced photocatalytic activities. Such a simple strategy by fabricating ultrathin type-II p-n heterojunctions also warrant promising applications in other areas such as optoelectronics, sensors etc. whereby efficient charge separations are needed.
研究领域:
材料化学
·
光催化
·
纳米材料
·
能源科学
·
半导体物理
·
环境催化
·
可持续能源
✓ 已验证
DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2022
·Vol. 45
·期 11
·1847-1855
·
IF 3.614
Ben Chen,Haibo You,Liqun Fang,Tingting Lin,Ping Xu,Chu Chu,Shengqiang Tong
Analytical enantioseparations of five N-alkyl drugs, fluoxetine hydrochloride, labetalol, venlafaxine hydrochloride, trans -paroxol, and atropine sulfate, were investigated by reverse phase high-performance liquid chromatography with sulfobutylether-β-cyclodextrin as chiral mobile phase additive. Effects of various factors such as composition of mobile phase, concentration of cyclodextrins, and column temperature on retention and enantioselectivity were studied. Apparent formation constant between methanol, acetonitrile, and sulfobutylether-β-cyclodextrin were determined to be 2.90 × 10 −3 and 1.00 × 10 −4 L mmol −1 under 25°C using UV-spectrophotometry. Van't Hoff plots were used to investigate thermodynamic parameters for enantiomers–stationary phase interaction and formation of inclusion complex. Two retention models were employed individually for evaluation of inclusion complexation between five racemates and sulfobutylether-β-cyclodextrin. The second model with complex adsorption was more accord with the retention behavior of fluoxetine hydrochloride, labetalol, and venlafaxine hydrochloride enantiomers, while the first model was more consistent with the retention behaviors of trans -paroxol and atropine sulfate. In the selected mobile phase, stoichiometric ratio for both of inclusion complex was found to be 1:1.
研究领域:
药学
·
分析化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 50
·40437-40443
·
IF 3.84
Lin Wang,Xiaomei Zhao,Yan Zhang,Wenqi Zhang,Tianrui Ren,Zhihong Chen,Feng Wang,Haifeng Yang
An intelligent PNIPAAm/AgNP composite film was fabricated by the simple assembly of silver nanoparticles on the surface of photo-polymerized PNIPAAm film via electrostatic interaction. Surface enhanced Raman scattering study and finite-difference time-domain simulation demonstrated that the local electric field intensity and the SERS intensity of this resultant composite film can be easily tuned by changing the interparticle distance triggered by temperature or solvent variations. The composite film showed a high stability in a polar organic solvent and concentrated saline solution. The smart composite film might find applications as a SERS sensor for temperature/solvent variation detection as well as a versatile SERS substrate for the detection of analyte in sea water and organic solvent.
研究领域:
材料科学
·
纳米技术
·
分析化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2021
·
IF 6.165
Tao Yang,Yukun Sun,Xianyang Meng,Jiangtao Wu,J. Ilja Siepmann
This work reports new experimental data for the density and viscosity of n -decane + CO 2 binary mixtures. A simultaneous density and viscosity measurement apparatus was redesigned using a vibrating–wire viscometer coupled with a vibrating–tube densimeter. The measurements for the pure component ( n -decane) and three different binary mixtures ( n -decane + CO 2 ), with mole fractions of n -decane of (0.4026, 0.2225, 0.1262), were carried out at temperatures ranging from (303.15 to 373.15) K and pressures up to 80 MPa. The expanded relative uncertainties ( k = 2, level of confidence = 0.95) were estimated to be 0.2% for density and 3.0% for viscosity over the entire measurement range, respectively. Densities were correlated as a function of temperature and pressure through a modified Tait–type equation with an average absolute percentage deviation less than 0.05%. To model the viscosity of the binary mixtures as a function of temperature, density, and composition, the extended hard–sphere method combined with simple quadratic mixing rules were used to describe our experimental data. Good agreement is found between experiments and correlations, which attests to the predictive capabilities of semi–empirical equations. In addition, Monte Carlo simulations in the isobaric-isothermal ensemble with the Transferable Potential for Phase Equilibria–United Atom (TraPPE–UA) force field were carried out to characterize the microscopic structure of the studied systems.
研究领域:
化学工程
·
流体力学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）