JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2011
·Vol. 110
·期 3
·1437-1442
·
IF 1.752
Lan X. Z.,Pei H. R.,Yan X.,Liu W. B.
Phase behavior of dodecane–tetradecane ( n -C 12 H 26 –C 14 H 30 , n -C 12 –C 14 ) binary system in bulk and confined in SBA-15 (pore diameters 8 nm; 15.9 nm) has been investigated by differential scanning calorimetry and transmission electron microscopy. The bulk system possesses some special phases relating to the rotator phase in normal alkanes. Dodecane–tetradecane mixtures confined in SBA-15 (8 nm) are a system miscible both in solid and liquid states with a phase diagram of a smooth curve. Dodecane–tetradecane system confined in SBA-15 (15.9 nm) exhibits not only solid–liquid (s–l) in all compositions but solid–solid transition in mole fractions of tetradecane 0.1–0.6, which forms a phase diagram of “loop line” shape. Melting temperatures of n -C 12 –C 14 /SBA-15 (8 nm) are lower than those of n -C 12 –C 14 /SBA-15 (15.9 nm) in all mole fractions. The evolution of the phase diagram of n -C 12 –C 14 confined in 8 nm, 15.9 nm pore sizes of SBA-15 and in bulk, respectively, shows a dramatic effect of confinement on phase behavior of normal alkane mixtures. The s–l phase boundary lines of n -C 12 –C 14 /SBA-15 (8, 15.9 nm) are fitted as \( T_{\text{m,r}}^{x} \) being [ \( xT_{{\text{m} ,r}}^{A} + \left( {1 - x} \right)T_{\text{m,r}}^{B} - D \) ], where D is a polynomial ∑ a
i
x
i , i = 1, 2,···, n ( A = C 14 , B = C 12 ).
研究领域:
物理化学
·
材料科学
·
纳米限域效应
·
热分析
·
软物质物理
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DOI
高影响因子
Analytical Methods
·
2019
·Vol. 11
·期 28
·3590-3596
·
IF 2.378
Can Wu,Pingcui Xu,Xuping Wang,Dan Shou,Nani Wang,Yan Zhu
Porous silica beads were coated with poly(vinyl alcohol) by using an in situ coating process. This system has been developed for use as a stationary phase in normal phase high performance liquid chromatography. In the conditions, the coating efficiency was controlled by the initial concentration of poly(vinyl alcohol). The polymer coating has been characterized by scanning electron microscopy, the nitrogen adsorption/desorption method, and infrared spectra analysis. The performance of the developed stationary phase was evaluated by separation of 5 nucleosides (thymidine, thymidine, uridine, adenine, and 2′,3′-dideoxyadenosine), 2 anthraquinones (rhein and emodin) and 1 terpenoid (oleanolic acid) in 10 traditional Chinese medicines. Comparison studies showed that the poly(vinyl alcohol) coated silica stationary phase showed better separation performance than bare silica beads. The obtained limits of detection for these analytes varied from 0.02 to 0.64 mg L−1. The linear ranges were from 1 to 1000 mg L−1 with the correlation coefficient (r) from 0.9990 to 0.9999. The average recoveries were in the range of 95.60–103.12%. This preparation process did not require chemical synthesis processes and techniques. The developed column offered a simple and convenient approach to obtain normal phase liquid chromatographic columns with satisfactory separation efficiency.
研究领域:
分析化学
·
中药学
·
药物分析
·
色谱技术
·
天然产物化学
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DOI
高影响因子
MRS Advances
·
2019
·Vol. 4
·期 36
·1973-1979
·
IF 0
Cong Zhao,Shichao Zhao,Yuanfang Zhao,Fang He,Ripeng Luo,Jingzhou Li,Shixi Zhao,Guodan Wei,Feiyu Kang
Cesium lead iodide perovskite (CsPbI3) with excellent optical and electrical properties have attracted numerous academic attentions. Specifically, the black cubic phase CsPbI3 with a direct band gap of 1.74 eV has been most appropriate materials for various optoelectronic applications, especially for photovoltaic (PV), Light-Emitting Diodes (LED) and photodetector applications1. However, the preferred cubic phase of bulk CsPbI3 (α-CsPbI3) is usually only stable at high temperatures and it will undergo an immediate phase transformation to orthorhombic phase (δ-CsPbI3) after fabrication at room temperature. In this work, we have discovered a convenient CVD method to investigate the growth behavior of the cubic α-CsPbI3 film on the porous alumina substrate. The lead iodide and cesium iodide were used as the precursors for the deposition of CsPbI3. The porous alumina with high surface area and large pore volume was used as growth substrate. It was shown that the porous alumina promoted the growth of CsPbI3 film by absorbing the precursor and increasing the nucleation density. The prepared CsPbI3 film emitted strong and stable red light under ultraviolet light excitation at room temperature and ambient atmosphere. The lead iodide was absorbed on the surface of the porous alumina firstly then reacted with cesiumiodide to form the CsPbI3. The successful preparation of the CsPbI3 by the direct CVD method paves the way for its large scale growth and application in optoelectronic devices.
研究领域:
材料科学
·
纳米技术
·
光学工程
·
表面科学
·
无机化学
✓ 已验证
DOI
RSC Advances
·
2017
·Vol. 7
·期 36
·22485-22491
·
IF 3.108
Hailiang Zhao,Shanshan Tang,Qun Zhang,Lin Du
The weak intermolecular interaction between 2,2,2-trifluoroethanol (TFE) and 3-chloro-2-methyl-1-propene (CMP) has been investigated by gas phase FTIR spectroscopy and DFT calculations. CMP offers two hydrogen bond docking sites to the hydrogen bond donor: the chlorine atom (O–H⋯Cl) and the CC π electron system (O–H⋯π). DFT calculations suggest that MeOH approaches CMP in five different orientations. The structural, energetic, and spectroscopic parameters of the most stable structures in each orientation were studied, and their binding energies range from −25.5 to −19.5 kJ mol−1. The docking to the π system is at least 1 kJ mol−1 more favored than the docking to the chlorine atom. The equilibrium constant for complexation (2.3 × 10−2) was determined from the experimental and calculated intensity of the OH-stretching transition. The Gibbs free energy of formation was found to be 9.3 kJ mol−1. The nature of the non-covalent interaction was analyzed with the atoms in molecules (AIM) method.
研究领域:
物理化学
·
结构化学
·
分子光谱学
·
量子化学计算
·
分子间相互作用
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·Vol. 41
·期 4
·5498-5504
·
IF 2.605
Shizhou Pu,He Zheng,Zhenlian Chen,Meiya Li,Zhongqiang Hu,Jianbo Wang,Huamin Zou
The microstructures of Bi 0.85 Nd 0.15 FeO 3 ceramics were investigated by using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), convergent-beam electron diffraction (CBED) and X-ray energy dispersive spectrometry (EDS). The superstructure phase related to 1/4( hh 0) p and 1/4(00 l ) p diffraction spots were observed in the samples. It is found that the superstructure phase can co-exist with R 3 c phase in a single grain. The bright and dark field images accompanied with SAED patterns provided evidences of the superstructure phase dispersed into the matrix with R3c symmetry and evolution of the domain. The ferroelectric domain wall was observed according to the displacement of Fe 3+ ions respect to Bi 3+ sub-lattice in the ferroelectric R 3 c phase based on HRTEM observations. The space group Pnam of the superstructure was identified by combining SAED and CBED techniques . EDS measurement revealed that the concentration of Nd in the Pnam phase is higher than that in R 3 c phase. This might mean that the transition from R 3 c to Pnam structure is due to the inhomogeneous distribution of the Nd concentration and the weakened stereochemical activity of Bi 3+ lone electron pair, arisen from the increase in Nd content.
研究领域:
材料科学
·
凝聚态物理
·
功能陶瓷
·
电子显微学
·
铁电材料
·
多铁材料
✓ 已验证
DOI
高影响因子
Small
·
2024
·Vol. 20
·期 26
·2310387
·
IF 13
Wei Luo,Yanli Yu,Yucheng Wu,Wenbin Wang,Yimin Jiang,Wei Shen,Rongxing He,Wei Su,Ming Li
Rational design of heterostructure catalysts through phase engineering strategy plays a critical role in heightening the electrocatalytic performance of catalysts. Herein, a novel amorphous/crystalline (a/c) heterostructure (a-CoS/Ni 3 S 2 ) is manufactured by a facile hydrothermal sulfurization method. Strikingly, the interface coupling between amorphous phase (a-CoS) and crystalline phase (Ni 3 S 2 ) in a-CoS/Ni 3 S 2 is much stronger than that between crystalline phase (c-CoS) and crystalline phase (Ni 3 S 2 ) in crystalline/crystalline (c/c) heterostructure (c-CoS/Ni 3 S 2 ) as control sample, which makes the meta-stable amorphous structure more stable. Meanwhile, a-CoS/Ni 3 S 2 has more S vacancies (S v ) than c-CoS/Ni 3 S 2 because of the presence of an amorphous phase. Eventually, for the oxygen evolution reaction (OER), the a-CoS/Ni 3 S 2 exhibits a significantly lower overpotential of 192 mV at 10 mA cm −2 compared to the c-CoS/Ni 3 S 2 (242 mV). An exceptionally low cell voltage of 1.51 V is required to achieve a current density of 50 mA cm −2 for overall water splitting in the assembled cell (a-CoS/Ni 3 S 2 || Pt/C). Theoretical calculations reveal that more charges transfer from a-CoS to Ni 3 S 2 in a-CoS/Ni 3 S 2 than in c-CoS/Ni 3 S 2 , which promotes the enhancement of OER activity. This work will bring into play a fabrication strategy of a/c catalysts and the understanding of the catalytic mechanism of a/c heterostructures.
研究领域:
材料科学
·
电化学
·
催化化学
·
纳米材料
·
能源材料
✓ 已验证
DOI
高影响因子
RARE METALS
·
2023
·Vol. 42
·期 12
·3985-3992
·
IF 8.8
Yang Yang,Liang Qing-Rong,Zhu Chun-Li,Zheng Guo-Zhong,Zhang Jian,Zheng Shou-Jun,Lin Yung-Chang,Zheng De-Zhi,Zhou Jia-Dong
Van der Waals coupling with different stacking configurations can significantly affect the optical and electronic properties of ultrathin two-dimensional (2D) materials, which is an effective way to tune device performance. Herein, we report a salt-assisted chemical vapor deposition method for the synthesis of bilayer V-doped MoS 2 with 2H and 3R phases, which are demonstrated by the second harmonic generation and scanning transmission electron microscopy. Notably, the mobility of the 3R phase V-doped MoS 2 is 6.2% higher than that of the 2H phase. Through first-principles calculations, we further reveal that this particular behavior is attributed to the stronger interlayer coupling of 3R compared to the 2H stacking configuration. This research can be further generalized to other transition metal chalcogenides and will contribute to the development of electronic devices based on 2D materials in the future.
研究领域:
材料科学
·
纳米科技
·
凝聚态物理
·
二维材料
·
半导体材料
·
表面科学
·
计算材料学
✓ 已验证
DOI
高影响因子
CRYSTENGCOMM
·
2019
·Vol. 21
·期 32
·4740-4746
·
IF 3.382
Jingbo He,Bo Sun,Yong Sun,Chengxin Wang
Although more than 250 polytypes of silicon carbide (SiC) crystals have been discovered, only very limited types of nanowires can be synthesized in a controllable manner. Both experimental and theoretical investigation reveal that 3C-SiC is the most stable form, which is the primary product of nanowires synthesized via various methods in thousands of reports. Although hexagonal phases, particularly the wurtzite structure with a bandgap of 3.33 eV is promising in optoelectronic applications, the fabrication of nanowires with theses phases is still rare. Herein, in this study, by precisely regulating the atmospheric conditions, we revealed that the CH4 supply resulted in the phase-selective growth between 3C- and 2H-SiC nanowires. As the CH4 flow rate increased, it was possible to fabricate 3C-SiC, hybrid 3C-/2H-SiC and 2H-SiC nanowires in a controllable manner. The possible mechanism is demonstrated accordingly. We believe this progress benefits the structural design and optoelectronic application of SiC nanowires.
研究领域:
材料科学
·
纳米技术
·
半导体物理
·
光电材料
·
晶体生长
✓ 已验证
DOI
高影响因子
CHIRALITY
·
2012
·Vol. 24
·期 5
·391-399
·
IF 2.35
Hui Yu,Chenghua Yin,Cunyu Jia,Yu Jin,Yanxiong Ke,Xinmiao Liang
Two “click” binaphthyl chiral stationary phases were synthesized and evaluated by liquid chromatography. Their structures incorporate S-(−)-1,1'-binaphthyl moiety as the chiral selector and 1,2,3-triazole ring as the spacer. These chiral stationary phases (CSPs) allowed the efficient resolution for a wide range of racemic BINOL derivatives, particularly for nonpolar diether derivatives and 3-phenyl indolin-2-one analogs. The chromatographic data showed that the π–π interaction was crucial for enantiorecognition of these CSPs. Loss of enantioselectivity observed on CSP3 , which are lacking the triazole ring linkage, indicated that the triazole ring linkage took part in the enantioseparation process, although it was remote from the chiral selector of the CSP. The substitution of the phenyl group at 6 and 6' positions can significantly improve the separation ability of the CSP. The chiral recognition mechanism was also investigated by tracking the elution orders and studying the thermodynamic parameters. Chirality 24:391–399, 2012 . Copyright © 2012 Wiley Periodicals, Inc.
研究领域:
分析化学
·
药物化学
·
色谱学
·
手性分离
·
有机合成
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 13
·1096
·
IF 2.8
Gu Wen,Liu Bingguo,Li Shunzi,Hu Baofu,Xu Jian,Wang Jian,Du Baoli
Cu 2 SnS 3 (CTS), as a potential thermoelectric (TE) material, the electrical and thermal transport properties are heavily determined by its original phase structure and the following phase evolution upon heating. Unlike previous studies that induced CTS phase transition by doping, this study used mechanical alloying powder as the precursor and successfully prepared phase-pure cubic (c-) and monoclinic (m-) CTS samples, as well as two-phase mixed samples with different percentage composition of c-CTS and m-CTS, by simply adjusting the hot pressing temperature. Firstly, phase structures of hot-pressed specimens were determined and confirmed by XRD refinement, SEM, TEM, and Raman spectroscopy. Secondly, thermodynamic property was analysis by DSC analysis, and phase evolution was detailed by analyzing specimens quenched at various temperatures. Then, the electrical and thermal transport properties were measured up to 500 °C, and were correlated with phase evolution analyzed above. Benefiting from cationic disorder, a maximum zT of 0.42 at 500 °C was achieved in c-CTS samples hot-pressed at 575 °C. The phase evolution of CTS was comprehensively investigated by using high-quality samples. The results indicate that phase transition is the potential mechanism for the doping effect in most studies, providing some guidance for improving the performance of environmentally friendly TE sulfides.
研究领域:
材料科学
·
凝聚态物理
·
无机化学
·
能源材料
·
热电转换
✓ 已验证
DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2015
·Vol. 38
·期 21
·3774-3780
·
IF 2.737
Fuyou Du,Xian Zheng,Lin Sun,Qun Qin,Lin Guo,Guihua Ruan
A polymerized high internal phase emulsion monolith was used as a novel sorbent for solid-phase extraction coupled with high-performance liquid chromatography and fluorescence detection for the determination of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline in environmental water samples. The polymerized high internal phase emulsion monolithic column was prepared by the in situ polymerization of the continuous phase of a high internal phase emulsion containing glycidyl methacrylate, styrene, and divinylbenzene in pipette tips, and then functionalized with iminodiacetic acid. The resulting monolith exhibited highly interconnected porosity and large surface areas, making it an excellent candidate as an solid-phase extraction sorbent for the enrichment of trace tetracycline antibiotics. Several factors affecting the extraction performance of polymerized high internal phase emulsion monoliths, including the pH of sample solution, the eluting solvents, the sample loading flow rate and volume, were investigated, respectively. Under the optimized conditions, the mean recoveries of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline spiked in pond and farm wastewater samples ranged from 78.1 to 119.3% with relative standard deviation less than 15%. The detection limits (S/N = 3) of the proposed method were in the range of 51–137 pg/mL. This study demonstrated that the monolithic polymerized high internal phase emulsion would be promising solid-phase extraction sorbents in the extraction and proconcentration of trace analytes from complex samples.
研究领域:
分析化学
·
环境科学
·
药物残留检测
·
色谱技术
·
样品前处理
✓ 已验证
DOI
高影响因子
Vegetable Research
·
2024
·Vol. 4
·期 1
·
IF 0
Chenxi Ji,Sihui Guan,Chenxu Liu,Chao Yu,Zhuping Yao,Hongjian Wan,Qingjing Ye,Guozhi Zhou,Huasen Wang,Yuan Cheng
Chili pepper (Capsicum annuum L.) is highly preferred by consumers owing to its distinctive flavor. Volatile organic compounds (VOCs) significantly influences the aromatic characteristics of chili peppers, thereby impacting their overall fruit quality. The study of chili pepper aroma remains at a nascent stage, with a notable gap in the literature regarding the composition and metabolic regulation of volatile flavor compounds in fresh chili peppers. This study focuses on the pepper cultivar var 'Qujiao 5' with rich fruit aroma, using headspace solid-phase microextraction full two-dimensional gas chromatography time of flight mass spectrometry (HS-SPME-GC × GC-TOFMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) detection technology platforms to analyze the VOCs present in green ripe pepper. A total of 1,558 VOCs were successfully identified. Utilizing the HS-SPME-GC × GC-TOFMS method pinpointed 933 substances, whereas the HS-SPME-GC-MS approach detected 773 compounds. Moreover, the two methods together identified 150 substances. Through the meticulous analysis of relative odor activity values (ROAV), it was conclusively determined that Pyrazine, 2-methoxy-3-(2-methylpropyl)- and 2-Nonenal, (E)- serve as pivotal volatile flavor compounds in chili fruit. Through the analysis of sensory flavor characteristics of chili peppers, it was found that fresh chili peppers have the main aroma characteristics of fatty, green bell pepper, and green, while also possessing modified odors such as floral and sweet. This research undertook a thorough comparative analysis of two different detection methods. It also meticulously examined the compositional and sensory attributes of the pepper VOCs, providing an essential reference for subsequent studies on the development of pepper fruit flavor quality.
研究领域:
植物学
·
食品科学
·
分析化学
✓ 已验证
DOI
危险品化学品经营许可证（带存储）