ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 28
·期 1
·1052-1060
·
IF 3.056
Sun Xu,Xu Li,Jiang Weina,Xuan Yan,Lu Wen,Li Zhong,Yang Shilong,Gu Zhenzhen
In the present study, a magnetic adsorbent, rhein-coated magnetic Fe 3 O 4 nanoparticle (RMNP), for Pb 2+ and Mg 2+ had been developed, and adsorption mechanism was studied via low-field NMR. RMNP was characterized by TEM, FTIR, and XRD. RMNP could adsorb and remove Pb 2+ and Mg 2+ from water and was successfully applied to remove Pb 2+ and Mg 2+ from wastewater, with satisfactory recovery rates and high adsorption capacities. The calculated maximum adsorption capacity for Mg 2+ and Pb 2+ was approximately 69.3 and 64.9 mg g −1 of RMNP, respectively, which was better than some results reported. Low-field NMR results showed that Pb 2+ or Mg 2+ enhanced the T 2 relaxation time of RMNP, which suggested that RMNP selectively coordinated with Pb 2+ or Mg 2+ and led to the aggregation of RMNP, furthermore removal of Pb 2+ or Mg 2+ from water. The standard curves for △T 2 -cation concentration exhibited good line correlation. The linear ranges were from 4.2 × 10 −6 to 2.0 × 10 −4 mol L −1 for Pb 2+ and from 5.0 × 10 −6 mol L −1 to 1.0 × 10 −4 mol L −1 for Mg 2+ , respectively. The limits of detection were 1.4 × 10 −6 mol L −1 for Pb 2+ and 2.1 × 10 −6 mol L −1 for Mg 2+ , respectively. In short, low-field NMR could clearly display the interaction between RMNP and Pb 2+ or Mg 2+ , even be used to detect Pb 2+ or Mg 2+ in suitable condition. Besides, this method could be expanded to study the interaction between other magnetic adsorbents and analytes.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FOOD SCIENCE AND TECHNOLOGY-MYSORE
·
2019
·Vol. 56
·期 2
·1027-1036
·
IF 1.85
Yang Shuang,Liu Jingsheng,Zheng Mingzhu,Zhao Chengbin,Cao Yong,Dong Yanjiao,Yaqoob Sanabil,Xiao Yu,Xu Xiuying
Cordyceps militaris ( C. militaris ) was utilized to ferment cornmeal by solid state fermentation. The main objective of this study was to investigate effect of fermentation on the dynamic state of water and microstructure distribution of water within cornmeal with Low-field nuclear magnetic resonance, as well as the effect on composition and microstructure properties. The spin–spin relaxation time (T 2 ) showed significant changes in solid-state fermented cornmeal. Principal component analysis further revealed that the variations within different fermentation stage could be discriminated by the T 2 parameters. Bulk water (T 22 ) was the main form of water present and lost in substrates. The weights of different indicators, as assessed by multiple regression analysis, demonstrated that there was a strong correlation between starch and T 2 relaxation. Scanning electron microscopy demonstrated that fermentation can cause the appearance of micropores. The longer relaxation time of T 22 during logarithmic period can be interpreted as a loosening of the structure at the starch hydrolysis, introducing more water into the structure. Thus, the differences in composition and structure of the substrate at different fermentation time produce different T 2 values.
研究领域:
食品科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2016
·
IF 3.187
Jiantao Chen,Xiangjun Gong,Chaoxi Zeng,Yonghua Wang,Guangzhao Zhang
It is known that urea can induce protein denaturation that can be inhibited by osmolytes. Yet, experimental explorations on this mechanism at the molecular level are still lacking. We have investigated the resistance of betaine to the urea-induced denaturation of lysozyme in aqueous solutions using low-field NMR. Our study demonstrates that urea molecules directly interact with lysozyme, leading to denaturation. However, betaine molecules interacting with urea more strongly than lysozyme can pull the bound urea molecules from lysozyme so that the protein is protected from denaturation. The number of urea molecules bound to a betaine molecule is given under different conditions. Proton NMR spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy reveal that the interaction between betaine and urea is through hydrogen bonding.
研究领域:
生物物理学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Foods
·
2021
·Vol. 10
·期 11
·2658
·
IF 4.35
Tao Wang,Nana She,Mengnan Wang,Bo Zhang,Jiaxing Qin,Jingyuan Dong,Guozhen Fang,Shuo Wang
The effects of storage temperature on the physicochemical properties and qualities of red brown rice were investigated in this study. The samples were vacuum-packed in nylon/polyethylene pouches and stored at 15 °C, 25 °C and 35 °C for 12 weeks. The moisture content decreased as storage time was prolonged. Rice stored at 15 °C and 25 °C had a lower falling range of water content compared to the samples stored at 35 °C. Free fatty acid values increased fastest when samples were stored at a high temperature, and the rise can be effectively delayed at low temperatures. The pH of residual cooking water and adhesiveness decreased, while the heating water absorption rate and hardness increased during storage for red and brown rice. Low-field nuclear magnetic resonance results indicate that water molecules migrated, the binding force of H protons became stronger and the bonds between molecules became closer with increased storage duration. Temperature had an obvious correlation with starch granules and protein structure, characterized by a scanning electron microscope and Fourier transform infrared spectroscopy. Low temperatures significantly retarded those changes. The results indicate that storage temperature is a vital factor affecting the physicochemical properties and qualities of red brown rice and provided reference and theoretical basis for the actual storage of red brown rice.
研究领域:
食品科学
·
农产品储藏与加工
✓ 已验证
DOI
高影响因子
LWT-FOOD SCIENCE AND TECHNOLOGY
·
2024
·
IF 6
Dan Peng,Qi Zhou,Min Su,Shaoshuai Zheng,Shuli Xie,Jun Li
Low-field nuclear magnetic resonance (LF-NMR) combined with chemometrics was used for the rapidly and nondestructively quantitative determination of carbonyl value (CV) of frying oils during frying process. The quality indices of frying oils during frying process were analyzed as well as the changes of its LF-NMR signal, followed by exploring the correlation between the quality indices of frying oils and the relaxation-characteristic indices and investigating the influences of modeling data and preprocessing methods on the modeling performance. Based on the echo decay curves data of LF-NMR and the relaxation-characteristic indices data, the prediction model of CV was established by partial least square (PLS), principal component regression (PCR), multiple linear regression (MLR), and support vector machine regression (SVR). Results showed that there was a significant correlation between CV and relaxation-characteristic indices ( p < 0.01) with both modeling data and preprocessing methods affecting the model performance. The prediction performance of non-linear SVR model was significantly superior to that of linear modeling methods (PLS, PCR, and MLR). The best prediction model of CV was built using the SVR method based on echo decay curves data. The root mean square error of prediction and coefficient of determination were 2.599 mmol/kg and 0.9873, respectively.
研究领域:
食品科学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF FOOD SCIENCE
·
2022
·Vol. 87
·期 9
·3953-3964
·
IF 3.693
Yuan Li,Cijian Li,Meiyu Chen,Zunying Liu,Mingyong Zeng,Yaqin Hu
Sous-vide cooking is a highly praised method used to cook muscle foods because of its desired effect of providing better sensory properties by maintaining texture. In this study, we further explored the effect of water on texture by revealing the mechanisms of moisture migration. Low field nuclear magnetic resonance (LF-NMR) showed that the nonflowing water in sous-vide cooking hairtail was 2.36 ± 0.33% higher than that in traditional cooking. Magnetic resonance imaging (MRI) was used to clarify the law of moisture migration induced by temperature, and the moisture migration of the sous-vide cooking hairtail was slower during the holding heating stage. The microstructure explained the change rules of the texture. The degree of change was consistent with the moisture migration level. Digitalizing analysis quantitatively verified the effect of sous-vide cooking on the hairtail microstructure. The low moisture migration rate of sous-vide cooking resulted in a less damaged microstructure of the hairtail, manifesting as a desirable texture. Practical Application LF-NMR and MRI showed that sous-vide hairtails exhibited a lower moisture migration rate. The holding heating stage only slightly changed the microstructure of the hairtail. The digitalizing analysis confirmed the moisture migration mechanisms. Heat-induced protein denaturation was closely related to the water state.
研究领域:
食品科学
·
生物物理学
✓ 已验证
DOI
高影响因子
Journal of Cleaner Production
·
2020
·
IF 7.246
Chengyong Gao,Tieling Xing,Xueni Hou,Yue Zhang,Guoqiang Chen
We report an improved printing ink of polyester fabric employed in the production process of inkjet printing . In the design of printing ink, the solubility parameters of reagent and HLB value of surfactant are used to prepare the ink. This production process does not require the pretreatment of polyester fabric to directly carry out inkjet printing. By regulating the intermolecular force relationship between the components of ink and the compactness of ink microstructure, it can improve the diffusion of ink on the surface of polyester fabric. The low-field NMR (LF-NMR) revealed the correlation between the fluidity and transverse relaxation time of main reagent solutions and ink. The test results show that there are three types of water: hydrogen-bond water, bound water and free water in main reagent solutions and ink. The LF-NMR was also used to investigate the relationship between ink viscosity and transverse relaxation time. It was observed that the transverse relaxation time (1084.4–410.3 m s, peak maximum time of T 22 ) of ink decreases with the increase of ink viscosity (2.3–11.1 mPa s). The viscosity and transverse relaxation time of ink is associated with the intermolecular force and the compactness of microstructure of ink. The formation of ink droplets was systematically observed by the ink droplet observation instrument. When the surface tension and viscosity of ink are 32.2–37.4 mN/m and 2.3–8.8 mPa s, respectively, the ink can be smoothly inkjet. With the increase of viscosity of the ink (2.3–8.8 mPa s), the sharpness of printing pattern is obviously improved, and the change rate of the line width (W) of the printing pattern is reduced from 52.6% to 4.4%. The microstructure of ink can bound the solvent of the ink, reduce the fluidity of the solvent, and improve the sharpness of the printing pattern. The test results of KES style and color fastness of the printed fabric show that the printed fabric fully meets the wearing requirements. Compared with other the soap liquid of printed fabric, the soap liquid of printed fabric RD-2B has strong UV absorption strength, the soap liquid RD-2B has a higher dye content. The characterization results of volatile organic compounds (VOC) in ink SDS R7 is 17.0 g/kg. The chemical oxygen demand (COD) values of printed fabrics RD-2B and SDS R7 are 150.0 and 102.0 mg/L, and the biochemical oxygen demand (BOD 5 ) values of printed fabrics RD-2B and SDS R7 are 130.0 and 97.7 mg/L. Compared with the common polyester fabric printing ink (ink RD-2B), the prepared ink has the characteristics of environmental protection, high production efficiency and low energy consumption, which has the potential to achieve green printing.
研究领域:
材料科学
·
纺织工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2021
·
IF 5.134
Wencheng Xia,Yuqiang Mao,Guangyuan Xie,Yaoli Peng
The filling of pores by flotation-reagent-contained water plays an important role in porous mineral flotation . This paper studied the role of sodium oleate (NaOL, a commonly used flotation reagent) solution in the in-situ wetting process of pores of porous active carbon using 1 H LF-NMR, FTIR as well as contact angle measurements. The floatability of active carbon particles wetted by NaOL solutions was evaluated by particles-bubble attachment measurements. The pore wetting percentage decreased as the NaOL concentration increased. The variation trend in pore wetting percentage by NaOL solutions was from fast to slow. Increasing the NaOL concentration contributed to achieve a lower pore wetting percentage as well as rate. The NaOL solution with a high concentration significantly improved the hydrophobicity of the sample, which further prevents the pore wetting process.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HYDROLOGY
·
2022
·
IF 6.708
Zhi Dou,Yongqiang Chen,Chao Zhuang,Zhifang Zhou,Jinguo Wang
Increasing human activities in cold regions have led to serious environmental problems due to non-aqueous phase liquids (NAPLs) contamination. However, the NAPLs redistribution driven by freeze–thaw (FT) cycles is not well understood. In this study, the redistribution of NAPLs in porous media subjected to FT cycles in a temperature range from 20 °C to −15 °C was investigated using the low-field Nuclear Magnetic Resonance (NMR) technique. The redistribution of NAPLs in the prepared samples with NAPLs saturation ranging from 13.56% to 72.05% was confirmed using the transverse spin-spin relaxation time ( T 2 ) distribution and the magnetic resonance imaging (MRI). Experimental results revealed that substantial remobilization and distribution of NAPLs occurred between the macropores ( T 2 greater than 300 ms) and the mesopores (60 ms < T 2 < 300 ms) while the NAPLs in the micropores ( T 2 < 60 ms) remained almost unchanged during 30 FT cycles. The main reason is attributed to the fact that the redistribution rate in micropores is much lower than in macropores and mesopores. Furthermore, the NAPLs content and the number of FT cycles were positively correlated for macropores while negatively correlated for mesopores. For the samples with low NAPLs saturation (e.g., S N =13.56% and 13.56%), the redistribution rate of NAPLs versus FT cycles exhibited an overall linear relationship for macropores and mesopores while a non-liner relationship for micropores. For all pore categories, the increment in S N can cause a remarkable deviation extent. The balance between capillary pressure and freezing-induced pressure was evaluated by the newly introduced dimensionless pressure ratio Δ P , which could help determine the ultimate mobilization and redistribution of NAPLs during FT cycles. Experimental tests suggested that the Δ P was much larger in macropores than in mesopores and micropores. This can explain the dramatic difference in the redistribution rate among different pore categories. This fundamental study is helpful in understanding the mobilization and redistribution mechanisms of NAPLs in cold regions.
研究领域:
环境科学
·
地球物理学
✓ 已验证
DOI
高影响因子
Soft Matter
·
2021
·Vol. 17
·期 39
·8973-8981
·
IF 3.679
Yahui Li,Junsheng Yang,Hong Cheng,Linkun Cai,Ke Ye,Zhijie Xia,Qianlei Zhang,Daoliang Wang,Wei Chen
The network structure in the amorphous domain of swollen iodine-doped poly(vinyl alcohol) (PVA) was systematically investigated by low-field (LF) NMR techniques to reveal the PVA–iodine complex formation mechanism. Three PVA–iodine complexes were obtained under different iodine concentrations (ciodine) of KI/I2 solution: (i) ciodine < 0.1 M: PVA–I3−/I5− complex only exists in the non-crystalline region, (ii) 0.1 M < ciodine < 1 M: formation of PVA–I3− complex I, and (iii) ciodine > 1 M: formation of PVA–I3− complex II. It was found that there is no intermediate-magnitude chain motion of PVA under dyeing conditions to induce the substance exchange, as evidenced by the unchanged second moment M2 (∼1.2 × 104 m s−2) at elevated temperature (<380 K). The introduction of iodine ions can affect the chain mobility of the interphase and mobile regions. With increasing ciodine, the chain dynamics become more restricted, as detected by the faster decay of the T2 relaxometry results, which further accelerates the complexation process. The residual dipolar coupling strength, Dres, obtained by the more quantitative double-quantum (DQ) NMR, increases abruptly at ciodine > 1 M. This suggests more constraints form in the amorphous network for the PVA–I3− complex II system. The constant defects fraction further reveals that the complexation prefers to happen along the tie chains. These results supply a possible formation pathway for the PVA–iodine complexes.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Geoenergy Science and Engineering
·
2025
·
IF 4.6
Heng Wang,Yuchen Xin,Yanbin Gong,Chunyu He,Pufu Xiao,Yangwen Zhu,Haiying Liao,Haiyan Zhu,Zhiwu Li,Bryan X. Medina-Rodriguez
Low-filed Nuclear Magnetic Resonance (LF-NMR) technique has been widely used to characterize rock properties and to investigate performance of CO 2 EOR. However, rare studies have been found to characterize the complex phase behavior variations in CO 2 -oil systems using the LF-NMR technique, i.e. interfacial tension reduction, viscosity reduction, oil swelling, hydrocarbon extraction and miscibility between gas-oil phases when pressure exceeds the minimum miscible pressure (MMP). This study explores the phase behavior and miscibility of CO 2 -hydrocarbon mixtures using the low-field nuclear magnetic resonance (NMR) techniques. First, the transverse relaxation time (T 2 ) of n-dodecane (C12) and n-hexadecane (C16) at different pressure and temperature conditions were measured as a baseline. Results show that the logarithm mean of T 2 (T 2lm ) has a good linear relationship with viscosity. Thereafter, T 2 distributions of CO 2 -hydrocarbon mixtures were continuously collected to investigate the evolutions of phase behavior induced by CO 2 -hydrocarbon interactions. Three stages were categorized from the T 2lm of CO 2 -hydrocarbon mixtures and pressure. As pressure increases for all cases, there is an observable rise in T 2lm values due to the viscosity reduction after CO 2 dissolution. At the subsequent higher pressures, as more CO 2 dissolves into the oil phase, the molecular mobility of oil components decreases due to increased intermolecular interactions and reduced free mean path. This effect causes a decline in T 2lm values, as the motion of oil molecules becomes more restricted. Finally, T 2lm stabilizes when miscibility is achieved, as the CO 2 -oil system transitions into a single-phase state Similar findings were observed for CO 2 -C12/C16 mixtures in glass-bead packs. In addition, interactions between CO 2 and light oil mixtures were investigated to validate the new technique. Results show that the MMP of the mixture is 8.5 MPa. As for CO 2 -oil in core plug, T 2lm increases first and stabilizes below and above the MMP, while higher pressure accelerates the stabilization process. This might be because oil close to the gaseous CO 2 becomes miscible, while for oil in the smaller pore spaces, a fully CO 2 -saturated phase exits as multi-contact miscible cannot be achieved simply through molecular diffusion. The findings in this study reveal the dynamic interactions between CO 2 and oil and provide an effective method for estimating the MMP, illustrating a significant potential application for commercial-scale CO 2 EOR and storage projects.
研究领域:
石油工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CEMENT AND CONCRETE RESEARCH
·
2025
·
IF 13.1
Jing Qiao,Chunsheng Zhou,Jingjing Feng,Miao Miao,Yanliang Ji,Linan Gu
Limestone powder (LS) with large particle sizes is widely used, but its effect on water migration behavior remains unclear. This study investigates the influence of LS and viscosity-enhancing admixtures (VEAs) on the water migration behavior and water distribution in fresh cement paste using 1 H low-field nuclear magnetic resonance (LF-NMR). Results indicate that LS increases the size of water migration channels, accelerates the water migration rate, and raises the bleeding ratio, while VEAs substantially mitigate the effects of LS. Compared to polyacrylamide, cellulose ether significantly slows down the water migration rate before 40 min, thereby reducing the bleeding ratio. Additionally, relaxation times were found to decrease during bleeding and can reflect the sedimentation process. It is confirmed that the pore structure of fresh paste exhibits fractal characteristics, with the fractal dimension closely correlating with water migration rates. The underlying mechanisms and their implications on material behavior are thoroughly analyzed and discussed.
研究领域:
材料科学
·
土木工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）