ENERGY & FUELS
·
2017
·
IF 3.091
Moxia Li,Helei Liu,Xiao Luo,Paitoon Tontiwachwuthikul,Zhiwu Liang
In this work, three promising tertiary amines—1-(2-hydroxyethyl)piperidine (1-(2-HE)PP), 3-(diethylamino)-1,2-propanediol (DEA-1,2-PD), and N-(2-hydroxyethyl)pyrolidine (1-(2-HE)PRLD)—were experimentally studied and the results presented in terms of pKa, the protonation calibration curves, and ion speciation plots. The pKa of these amines were determined in the temperature range of 294–320 K. The protonation calibration curves for the three amines were also developed based on 13C NMR detection. In addition, ion (amine, amineH+, HCO3–, and CO32–) speciation plots for the three tertiary amines were developed at the temperature of 298 K, at the amine concentration of 1.0 M, over the CO2 loading ranges of 0–0.897 mol CO2/mol amine for 1-(2-HE)PP, 0–0.915 mol CO2/mol amine for DEA-1,2-PD, and 0–0.927 mol CO2/mol amine for 1-(2-HE)PRLD by using the pH method, the 13C NMR method, and the pH + 13C NMR method. By comparing the ion (amine, amineH+, HCO3–, and CO32–) concentrations of the three tertiary amines obtained from these three methods, it can be concluded that each of these three methods could be used to develop the ion speciation plots of amine–CO2–H2O systems, but there are some significant differences between them.
研究领域:
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Food Measurement and Characterization
·
2021
·Vol. 15
·期 3
·2716-2726
·
IF 2.431
Qian Junqing,Zhao Changyan,Zhu Hanxiao,Tong Jun,Zhao Xiaohua,Yang Haiyan,Guo Hui
Walnut oil is endowed with a variety of physiological functions due to abundant natural compounds, and the effect of unsaturated fatty acids is crucial. In order to accurately and conveniently detect the fatty acids components and content in walnut oil, a quantitative method was developed to detect fatty acids content based on the 1 H-NMR and 13 C-NMR techniques. In addition, HPLC combined with MS was used to conduct qualitative analysis. HPLC method with an evaporative light-scattering detector was for the quantitative analysis and the fatty acids content was compared with the content from NMR. The result showed that there was no significant difference between 1 H-NMR, 13 C-NMR and HPLC (P > 0.05) and indicated that the NMR has the potential to be applied as a routine method for the analysis of fatty acids content in walnut oil.
研究领域:
分析化学
·
食品科学
·
营养学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2018
·
IF 4.513
Kemeng Shi,Christian Marcus Pedersen,Zhaohui Guo,Yanqiu Li,Hongyan Zheng,Yan Qiao,Tuoping Hu,Yingxiong Wang
The tautomer distributions of d ‑fructose, a popular model compound for biorefinery , in various lower alcohols and DMSO‑ d 6 (ROHs/DMSO‑ d 6 ) mixtures at 298 K were investigated by quantitative 13 C NMR. The tautomer distributions of d ‑fructose in ethanol/DMSO‑ d 6 and methanol/DMSO‑ d 6 with different volume ratios of alcohols to DMSO‑ d 6 were also examined. For these normal alcohols (methanol, ethanol, n ‑propanol and n ‑butanol)/DMSO‑ d 6 , the tautomer distribution of d ‑fructose in methanol/DMSO‑ d 6 exhibited the shortest equilibration time (46 h) and the lowest concentration of β‑furanose (39.0%) at equilibrium. The fraction of fructofuranose (α‑furanose and β‑furanose) at equilibrium and time needed to reach equilibrium in branched chain alcohols/DMSO‑ d 6 obey the following order: 2‑propanol/DMSO‑ d 6 (62.2%, 320 h) > tert ‑butanol/DMSO‑ d 6 (61.6%, 307 h) > 2‑butanol/DMSO‑ d 6 (60.6%, 216 h) > isobutanol/DMSO‑ d 6 (57.8%, 134 h). For the diols/DMSO‑ d 6 , the time for the tautomer distribution of d ‑fructose to reach the equilibrium was found to be: 1,4‑butanediol/DMSO‑ d 6 (113 h) > 1,2‑propanediol/DMSO‑ d 6 (38 h) > ethylene glycol/DMSO‑ d 6 (36 h). For ethanol/DMSO‑ d 6 and methanol/DMSO‑ d 6 with respectively different volume ratios, the experimental results showed that the high concentration of ethanol or methanol increases the conversion rate of tautomers.
研究领域:
生物化学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2018
·
IF 3.024
Yuning Meng,Xindian Wang,Feng Zhang,Zhibing Zhang,Youting Wu
Dual amino functionalized ionic liquid tetramethylammonium lysinate ([N1111][Lys]) was synthesized and mixed with 2-[2-(dimethylamino)ethoxy]ethanol (DMEE) to obtain a series of nonwater absorbents for CO2 capture. The density and viscosity of the IL hybrids were measured. Using dual-vessel absorption system, CO2 absorption capacity and rate were investigated over a wide range of IL mass fractions (5–100%) to evaluate the influence of DMEE content, and 20% was chosen for further studies including influences of temperature and regeneration performances. Mass transfer coefficients with constant absorption area were calculated from apparent absorption rate constant. Fourier transform infrared (FT-IR) and 13C NMR spectra were applied to indicate the absorption process and mechanism. This new nonwater mixed system was proved to have high absorption capacities and prominent regeneration efficiency under mild conditions (80 °C).
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Food Analytical Methods
·
2019
·Vol. 12
·期 4
·991-997
·
IF 2.413
Li Yunyan,Mao Wenping,Liu Chaoyang,Zhang Xu,Wang Junfeng
We propose a J -selective quantitative distortionless enhancement by polarization transfer ( J -selective QDEPT) 13 C NMR method with enhanced sensitivity for accurate determination of the fatty acid compositions of edible oils. The J -selective QDEPT protocol is developed by targeted optimization of the known Q-DEPT + experiment. Based on the one-bond C-H J -coupling constants ( 1 J CH ) which can be measured with the heteronuclear two-dimensional J -resolved 13 C NMR spectrum, it is possible to optimize the polarization transfer delay Δ and the reading pulse angle ⊖ , thus enabling the QDEPT experiment further enhancing 13 C resonance signals which have narrow 1 J CH ranges over the traditional untargeted Q-DEPT. For edible oil applications, it is demonstrated that this procedure brings a 2.2 enhancement factor against 1.3 of the traditional untargeted Q-DEPT compared to the standard inverse-gated 13 C experiment, even with a shorter relaxation delay for the two QDEPT experiments. Another advantage of J -selective QDEPT is that a smaller number of quantitative scans are needed to reach a uniform enhancement for different CH n ( n = 1, 2, 3) groups. These features of the J -selective QDEPT are particularly attractive for batch analysis in the food industry.
研究领域:
食品科学
·
分析化学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Dongfang Zhao,Shoulong Dong,Liju Bai,Dongyang Li,Helei Liu
The concentration profiles of all chemicals obtained in the Amine-CO 2 -H 2 O system based on the Vapor-liquid equilibrium (VLE) plots are essential for the analysis and understanding of the kinetics. This work aims at obtaining accurate and reliable VLE plots of 3DMA1P via both experimental and mathematical methods. VLE plots are essential for understanding the reaction process and mechanism of carbon dioxide absorption into amine solutions. The experiments were conducted over a concentration range of 1 ∼ 2 mol/L, temperature of 298 K, and CO 2 partial pressure of 15 kPa. Regarding the experimental method, 13 C NMR detection was performed to generate concentrations of Amine and AmineH + based on the protonation calibration equation. The results showed that the 13 C NMR method had little difference between the results of mass conservation calculation and charge conservation calculation under different CO 2 loading. Among the mathematical methods, the results obtained by the pH method involving charge conservation were quite different from those calculated by mass conservation, while the D-M model method strictly following the theoretical system satisfied both the mass and charge conservation. The distribution curves of the concentration of each species obtained by the three methods were compared. It was found that 13 C NMR and D-M model method could secure closer and more accurate results than the pH method. In conclusion, both the 13 C NMR method and the D-M model method plots are useful for obtaining accurate and reliable VLE plots for the 3DMA1P-CO 2 -H 2 O system, as well as for other monoamine and mixed amine systems.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2026
·Vol. 40
·期 33
·18014-18027
·
IF 6
Wang Chong,Xia Runtian,Cai Xinheng,Zhang Zhihua,Wang Wei,Zhang Qundan
To
support the optimization and screening of catalysts for the
residue hydrodesulfurization (HDS) process, it is essential to conduct
in-depth characterization of sulfur-containing compounds (SCCs) in
the residue. In this study, a combination of 13 C-methylation
derivatization and 13 C nuclear magnetic resonance (NMR)
spectroscopy was employed to investigate the structural details of
sulfur-containing compounds in residual oil on the basis of diverse
model compounds. The results showed that the chemical shift of the 13 C-methyl group attached to the sulfur atom in the internal-type
thiophenic aromatic compounds (such as dibenzothiophene) is greater
than 35 ppm, while the chemical shift of the 13 C-methyl
group attached to the sulfur atom in the thiophenes, terminal-type
thiophenic aromatic compounds (such as naphthothiophene), and those
with alkyl substituents is 29–35 ppm. When the 13 C-methyl is substituted on the carbon atom in the terminal thiophene
ring, its chemical shift is within the range of 10–15 ppm.
In addition, the chemical shift range of 15–29 ppm is observed
and attributed to the 13 C-methyl and alkyl groups substituted
on the aromatic ring in both the internal-type and terminal-type thiophenic
aromatic compounds. These rules were further applied to the characterization
of the residue oil and its hydrodesulfurization product. The analytical
results indicate that the molecular structure of refractory sulfur
compounds in the deep hydrotreated residue is dominated by the sterically
hindered internal-type thiophenes with long alkyl side chains. The
established method can be used for the characterization of isomers
of sulfur-containing compounds in the residue and other petroleum
products, thereby providing reference information for subsequent hydrodesulfurization
and hydrogenation research.
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Yongyan Pei,Mengqi Zhang,Xiaoying Wu,Hua Cao
Seaweed polysaccharides exhibit skin-protective properties, yet species-specific structural determinants of their functionalities remain unexplored. Here, polysaccharides from Sargassum, Ulva and Laminaria digitata were extracted via response surface methodology (RSM)-optimized protocols, quantified by HPLC (monosaccharide composition, sulfate content) and characterized by Fourier transform infrared spectroscopy (FTIR), 13 C nuclear magnetic resonance ( 13 C NMR) and gel permeation chromatography (GPC). Functional validation across cell (RAW264.7 macrophages, HaCat and chorioallantoic membrane assays), ex vivo (antioxidant capacity, UV absorption, hygroscopicity) and in vivo models (rat auricle edema, skin irritation) confirms both efficacy and safety for cosmeceutical use. Sargassum contains a dominant 599.87-kDa fucoidan with diagnostic NMR signals at δ15.05 ppm (C6-CH₃ of L-fucose) and δ100.25–101.87 ppm (anomeric C1), alongside FTIR bands for sulfate (1250 cm −1 ), fucose-specific C–O–S bending (840 cm −1 ) and hydration-associated O H bending (1650 cm −1 ), correlating with its antioxidant activity (62.67 ± 5.22 % hemolysis inhibition). Ulva comprises a 22.21-kDa ulvan exhibiting NMR peaks at δ107.05 ppm (C1 of α-L-rhamnose-3-sulfate) and δ16.86 ppm (C6-CH₃ of rhamnose), plus FTIR signatures of sulfate (1240 cm −1 ), broad O H stretching (3400 cm −1 ) and rhamnose C H deformation (890 cm −1 ), enabling hygroscopic hydrogel formation and UV shielding (61.31 ± 0.78 %). Laminaria digitata features a 180.29-kDa alginate with NMR signals at δ176.89 ppm (carboxyl carbon) and δ102.78–103.54 ppm (anomeric carbons of mannuronic and guluronic acid residues), and FTIR bands for carboxyl (1720 cm −1 ) and bound water (1640 cm −1 ), driving moisturization (64.81 ± 10.01 %) and hyaluronidase inhibition (27.26 ± 2.03 %) . All polysaccharides demonstrated zero irritation and excellent biocompatibility, thus supporting species-specific cosmetic applications: Sargassum for antioxidant-focused formulations, Ulva for UV-protective products and Laminaria digitata for hydration and anti-inflammatory-oriented cosmeceuticals.
研究领域:
海洋生物化学
·
化妆品科学
·
天然产物化学
·
光谱分析
·
多糖表征
·
功能生物材料
✓ 已验证
DOI
PubMed
高影响因子
FUEL
·
2022
·
IF 8.035
Peng Liu,Yuanyuan Zhang,Tieying Pan,Dexiang Zhang,Lishi Chen,Changrong Sun
Coal conversion to material or chemical by pyrolysis is the main methods for achieving carbon neutrality. To predict correct pyrolysis behavior, accurately quantifying carbon structural types of complex coal discussed in this study is significative. Carbon structural types in coal based on 13 C NMR Cp/MAS TOSS spectra were accurately quantified by coupling standard curve and peak-fitting method to reduce nuclear overhauser effect (NOE). The H/C atomic ratio and aromaticity is used to verify the accuracy of this method. The pyrolysis behavior was predicted by pyrolysis Gas Chromatography-Mass Spectrometer (Py-GC-MS), thermogravimetric analysis (TG), and fix-bed slow pyrolysis according to correction carbon structure. The results show that the H/C atomic ratio calculated by correction carbon structure is agreed with that from ultimate analysis, as well as aromaticity. Their correction relative deviations are below 10%, farther lower than experimental value, increasing with the increment of C daf %. The correction carbon structure evolution during pyrolysis is coincided with general conclusion and Py-GC-MS analysis. The mono-aromatics and phenolics are evaluated by correction carbon structure. It is significantly fundamental study for carbon material to chemicals from micro-angle. These results are also a guide for accurate calculation and simulations of quantum chemistry.
研究领域:
能源科学
·
材料化学
✓ 已验证
产品关联
DOI
高影响因子
BIOTECHNOLOGY LETTERS
·
2017
·Vol. 39
·期 8
·1229-1235
·
IF 1.73
Wang Qianqian,Xu Yixiang,Xu Jiaqi,Wang Xudong,Shen Chen,Zhang Yan,Liu Xiufeng,Yu Boyang,Zhang Jian
Objectives To characterize glycosyltransferases from Bacillus subtilis ATCC 6633 and investigate their substrate specificity towards plant polyphenols. Results Among the cloned and expressed six UDP-glycosyltransferases (BsGT1-6), BsGT-1 showed activity with a wide range of polyphenols: morin, quercetin, alizarin, rehin, curcumin and aloe emodin. The gene of BsGT-1 has an ORF of 1206 bp encoding 402 amino acids. The recombinant enzyme was purified to homogeneity by Ni–NTA affinity chromatograph, and its biochemical characteristics were identified by HPLC–UV/MS, 1 H-NMR and 13 C-NMR. BsGT-1 has an MW of approx. 46 kDa as indicated by SDS-PAGE; its activity was optimal at 40 °C and pH 8.5. The Km value of BsGT-1 towards morin was 110 μM. Conclusions BsGT-1 from B. subtilis was cloned. It had high catalytic capabilities towards polyphenols which would make it feasible for the structural modification of polyphenols.
研究领域:
生物化学
·
分子生物学
·
酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2024
·
IF 6.5
Longyu Wang,Haibo Jin,Zhichang Liu,Suohe Yang,Guangxiang He,Haiyan Liu,Xianghai Meng,Chunming Xu
The formation mechanism and pathway of HMF from fructose dehydration were investigated using in-line FTIR monitoring and in-situ 13 C NMR in this study. The results of the infrared absorption spectrum obtained at different time intervals during the reaction process showed significant inconsistencies with the acyclic pathway. However, the in-situ NMR analysis revealed the direct observation of two intermediates, fructose furan and (4R-5R)-4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-formaldehyde, providing direct evidence to support the cyclic carbocation pathway. This study also included theoretical analysis of the intermediates involved in the key steps of various reaction pathways using density functional theory (DFT) calculations. The key steps in the cyclic pathway were found to have lower activation energy compared to the acyclic pathway, while exhibiting significant differences in electronegativity at the reaction sites. The computational results not only reveal but also provide support for the rationality of the cyclic formation mechanism. The response surface methodology (RSM) was utilized to optimize the preparation process of HMF through fructose dehydration. It enabled determination of the significance order for each factor (reaction temperature > reaction time > mass percentage of water in the solvent) and identification of the optimal process conditions (reaction time of 3.5 h, reaction temperature of 143.5 °C, mass percentage of water in the solvent of 5.0 %, and maximum yield of 5-HMF reaching 82.4 %).
研究领域:
化学工程
·
分析化学
·
计算化学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 46
·6745-6754
·
IF 5.582
Zhi-Hao Zhang,Shan-Qing Peng,Shumeng Chi,Hanyuan Chen,Lei Fan,Yan Liu,Xiaohua Ma,Mu-Hua Huang
Porous organic polymers (POPs) are a class of promising materials for overcoming environmental and energy issues worldwide. However, their amorphous nature makes structural characterization in the solid state very challenging. In addition, developing facile synthesis methods and applications for POPs with novel structures remain urgent issues requiring improvement. In this work, novel porous organic polymers (named BIT-POPs) with isolated trans-alkene linkages were synthesized via cross-linking bis-norbornene via ring opening metathesis polymerization (ROMP) in an extremely mild and fast manner. Spectral editing approaches, such as 13C-CPMAS, 13C-CPPI, and 13C-CPNQS, relating to solid-state NMR were used to distinguish the overlapping NMR signals of insoluble BIT-POPs, and two-dimensional 1H–13C HETCOR spectra were used. Also, BIT-POP-5 was added to a polysulfone matrix as a porous filler to form a mixed-matrix membrane, which showed a 126% increase in CO2 permeability during gas separation.
研究领域:
材料科学
·
环境科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）