Reaction Kinetics Mechanisms and Catalysis
·
2021
·Vol. 133
·期 1
·371-382
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IF 2.081
Song Wenjing,Song Mengxue,Jiang Xingmao,Yi Xiaodong,Lai Weikun
Hydrolytic cleavage of C–O bond was systematically studied in acidic/alkaline aqueous solution. For phenethoxybenzene (PEB) hydrolysis, 2-phenylethanol and phenol were formed as main products in AlCl 3 solutions, whereas styrene was preferred with Na 2 CO 3 . After a quantitative evaluation of the kinetics of elementary steps, it was concluded that both AlCl 3 and Na 2 CO 3 promoted protons assisted C–O bond scission in H 2 O, whereas alkaline enhanced the dehydration of produced 2-phenylethanol. Kinetic and isotope labeling experiments demonstrated that the hydrolytic rates of PEB were first order with respect to substrate concentrations, hydrolytic cleavage of C–O bond was rate-determining step. The study shed light on the promotional effects and hydrolytic mechanism over acid/base-catalyzed lignin depolymerization in water. Graphic abstract
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FOOD CHEMISTRY
·
2021
·
IF 7.514
Zhaohua Huang,Baozhong Guo,Chong Deng,Can Tang,Chengmei Liu,Xiuting Hu
W/O/W emulsions were easily prepared by oleogelation of the oil phase using rice bran wax (RBX) and their microstructure, stability, rheology and protection of proanthocyanidins and β-carotene were investigated. Formation of the W/O/W emulsion was confirmed using confocal laser scanning microscopy and staining of the inner aqueous phase by tartrazine . The average particle size and viscosity of the emulsion increased as the RBX concentration increased. Moreover, RBX increased the stability of the emulsion and the emulsion was the most stable when the RBX concentration was 8.0% or 10.0%. On the other hand, the W/O/W emulsions were used to simultaneously encapsulate proanthocyanidins and β-carotene. Specifically, proanthocyanidins and β-carotene in RBX-containing emulsions were more stable and had higher bioaccessibility than in the emulsion without RBX. Besides, both their chemical stability and bioaccessibility reached the maximum value when the RBX concentration was 8.0% or 10.0%. In summary, the optimal RBX concentration was 8.0%.
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POLYMER
·
2021
·
IF 4.43
Xiaotao Wang,Yebin Yang,Chuang Liu,Huiling Guo,Zhuofan Chen,Junyong Xia,Yonggui Liao,Chak-Yin Tang,Wing-Cheung Law
A near infrared (NIR) and pH dual-responsive nanocomposite, composed of a lanthanide-doped upconversion nanoparticle (UCNP) core and a transformable poly- o -nitrobenzyl shell, was prepared by the distillation precipitation polymerization and template method. The poly- o -nitrobenzyl shell can undergo hydrophobic-hydrophilic transformation upon an irradiation of 980 nm, rendering the capability of NIR-activated drug release. The anticancer drug , doxorubicin (DOX), can be loaded into these nanocomposites with a loading efficiency of 7.23 wt%. Furthermore, pH responsiveness caused by the hydrogen bond and charge interactions between DOX and nanocapsules can trigger the release of drugs at low pH. Under visible light irradiation and neutral (pH 7.4) conditions, the cumulative release of DOX was only 8.35% after 300 min, while it reached 59.5% under the synergistic effect of NIR irradiation and acidic conditions. The Baker-Lonsdale model was used to describe the drug release kinetics of this system, and the diffusion coefficient (3 DC s / r 0 2 C 0 ) and R 2 under different conditions were determined to be 4.15 × 10 −6 and 0.98 (pH 7.4 and visible light), 2.64 × 10 −5 and 0.99 (NIR light), 3.26 × 10 −5 and 0.97 (pH 4.5 and visible light), 2.59 × 10 −4 and 0.99 (pH 4.5 and NIR light), respectively. This controlled release feature makes the nanocomposite a promising therapeutic agent for treating diseases.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2020
·
IF 2.369
Xuemei Zhang,Xiaojie Yang,Jie Jian,Chungui Jian,Jie He,Hongwei Wang,Wangxin Kong,Guangjin Shangguan,Meifang Xia
Liquid–liquid equilibrium (LLE) data of the ternary system 2-methyl-2-butanol + water + o-xylene were determined at 303.2, 313.2, and 323.2 K under 101.3 kPa. The extraction capacity of o-xylene is expressed by selectivity, which is more than 118 and decreases with the increase of temperature. The quality of the experimental LLE data is verified by calculation of the overall mass balance and alignment between the conjugated phases and overall compositions. The experimental LLE data were regressed by the NRTL and UNIQUAC models, and the binary interaction parameters were obtained. And the root-mean-square deviations (RMSDs) are less than 1.02%.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Lei Wang,Yujie Li,Dong Xiang,Weimin Zhang,Xinpeng Bai
Lutein is a hydrophobic carotenoid with diverse bioactivities. For encapsulating the molecule in a novel method, we prepared two emulsions from xanthan and propylene glycol alginate at the ratios of 3:7 and 4:6. The instability index and particle size of the emulsions were determined using a stability analyzer and laser particle size analyzer. The influence of crystallization on the emulsions was observed under a polarizing microscope. The effects of centrifugal force and storage on the lutein emulsions were analyzed by measuring the changes in absorbance. The results showed that the emulsion fabricated by xanthan and propylene glycol alginate at the ratio of 4:6 was highly stable, and crystals were dispersed when xanthan and propylene glycol alginate existed. These results revealed that the hydrophobicity and absorption kinetics of emulsifiers would determine the stability of emulsion when the viscosity of emulsifiers reached a certain value, and the stability of emulsions would affect the stability of lutein in the emulsions.
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Catalysis Science & Technology
·
2020
·Vol. 10
·期 15
·5298-5305
·
IF 5.721
Xuanxuan Yang,Yu Guo,Yongbing Lou,Jinxi Chen
Rational design of highly efficient photocatalysts based on molybdenum cocatalysts is prospective to achieve hydrogen evolution under visible light. Herein, Mn0.5Cd0.5S nanoparticles decorated with O-doped MoS2 nanosheets (denoted as O-MoS2/Mn0.5Cd0.5S) were successfully synthesized. The incorporation of O atoms, which could trigger defects and enlarge the interlayer distance of MoS2, was achieved by a simple hydrothermal method. The performances of O-MoS2/Mn0.5Cd0.5S composites for catalyzing hydrogen evolution are rapidly enhanced with increasing contents of O-MoS2. The resultant 12 wt% O-MoS2/Mn0.5Cd0.5S composite exhibits superior stability and a satisfactory hydrogen production rate up to 84.32 mmol g−1 h−1 and the apparent quantum efficiency at 420 nm is 46.92%, which is 3.18 times higher than that of Mn0.5Cd0.5S nanoparticles. To the best of our understanding, such an exceptional activity of 12 wt% O-MoS2/Mn0.5Cd0.5S prepared in this work for hydrogen evolution is one of the highest among all reported Mn–Cd–S-based catalysts. The markedly strengthened activity is attributed to the improved light absorption and effective separation of photoinduced carriers between O-MoS2 nanosheets and Mn0.5Cd0.5S nanoparticles. This work indicates that O-MoS2 is a potential cocatalyst for the rational construction of efficient photocatalysts.
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Nuclear Materials and Energy
·
2020
·
IF 2.213
Xinyi Yang,Liangliang Song,Bo Chang,Qi Yang,Xiaodong Mao,Qunying Huang
The low solubility of gadolinium (Gd) limits its application in iron-based neutron shielding alloys. In this study, a high content of Gd up to 7.87 wt.% was added into 316L stainless steel by mechanical alloying (MA) of Gd 2 O 3 with 316L powder. Neutronics calculation results showed that the shielding efficiency of 0.2 mm thick 7.87 wt.% Gd-316L alloy was equivalent to that of 33 mm thick 316L for thermal neutrons. Microstructure analysis indicated that Gd-Si-O particles with an average size of 12.5 nm were uniformly dispersed in the matrix. It revealed that Gd 2 O 3 dissolved into the 316L matrix during MA and re-precipitated at around 780 °C as Gd 2 SiO 5 by XRD and TG-DSC. This study provides a novel Gd-containing alloy designed to achieve integration of structural alloys with good neutron shielding function for future application.
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TALANTA
·
2020
·
IF 5.339
Xue Han,Zhen Meng,Lian Xia,Fengli Qu,Rong-Mei Kong
This study demonstrates a novel and convenient ratiometric fluorescent method for the detection of alkaline phosphatase (ALP) activity. Amino-functionalized mesoporous silica nanoparticle-gold nanoclusters (MSN-AuNCs) nanocomposites were integrated with o-phenylenediamine (OPD) to form a ratiometric fluorescence nanoplatform. The presence of ALP induced the generation of quinoxaline (QX) derivative which called 3-(dihydroxyethyl)furo[3,4-b]quinoxaline-1-one (DFQ) with strong fluorescence emission at 450 nm, while the orange-red fluorescence of MSN-AuNCs at 580 nm was slightly quenched. Meanwhile, an obvious fluorescence color change from orange-red to purple and finally to blue can be observed by naked eyes with the increasing of ALP concentration. Therefore, employing the fluorescence emission of DFQ at 450 nm as the reporter signal and the fluorescence emission of MSN-AuNCs at 580 nm as a reference signal, a sensitive ratiometric detection method for ALP was developed. Quantitative detection of ALP activity in the linear range from 0.2 to 80 U/L with a detection limit of 0.1 U/L can be realized in this way, which endows the assay with high sensitivity enough for practical detection of ALP in human serum samples.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2020
·Vol. 24
·期 3
·633-640
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IF 2.646
Liu Bingqian,Shi Weiping,Yang Yani,Cai Jie
In this paper, a simple and feasible immunoassay protocol with signal amplification for sensitive determination of alpha fetoprotein (AFP, used as a model) by using new enzyme-induced Fenton reaction (EIFR) accompanying the oxidation of o-phenylenediamine (OPD) system. We discovered that glucose oxidase (GOx) has the ability to stimulate in situ Fenton reaction coupling the oxidation of OPD. GOx-catalyze of glucose results in the formation of hydrogen peroxide (H 2 O 2 ). It can catalytically oxidize Fe 2+ to Fe 3+ , meanwhile producing hydroxyl radicals (•OH). The latter effectively initiated the catalytic oxidation of o-phenylenediamine (OPD) to 2,2-aminoazobenzene (DAP), resulting in the production of an electrochemical signal. On the basis of EIFR-OPD system, a new immunoassay protocol with GOx/anti-pAb 2 -conjugated gold nanoparticle (Ab 2 -AuNP-GOx) detection antibody can be designed for the detection of target AFP on capture antibody–functionalized transparent 96-well polystyrene microplate, monitored by recording the current peak of the generated DAP. The electrochemical current shows to be positively correlated with the concentration of target AFP. Under optimal conditions, the proposed assay exhibited good electrochemical responses for detecting target AFP in the range of 1.0 pg mL − 1 to 100 ng mL −1 with a detection limit (LOD) of 0.5 pg mL −1 (0.5 ppt) estimated at the 3 S blank level. Additionally, the precision, reproducibility, specificity, and method accuracy were also investigated with acceptable results. Importantly, the EIFR-OPD system can be further extended for the determination of other protein or biomarkers by controlling the specific recognition system (antibody or aptamer).
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CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Qun Liu,Yan Li,Xiaodeng Yang,Shu Xing,Congde Qiao,Shoujuan Wang,Chunlin Xu,Tianduo Li
Chitosan has attracted much attention in drug delivery, however, carboxymethyl chitosan (CMC)-based self-aggregated nanocarriers are seldom reported. In this paper, two kinds of CMC-based pH-responsive amphiphilic chitosan derivatives, N -2-hydroxylpropyl-3-butyl ether- O -carboxymethyl chitosan (HBCC) and N -2-hydroxylpropyl-3-(2-ethylhexyl glycidyl ether)- O -carboxymethyl chitosan (H2ECC), have been synthesized by the homogeneous reaction. The molecular structures were characterized by FTIR, 1 H NMR and 13 C NMR. The optimum reaction condition was obtained based on the data of 1 H NMR spectrum: reaction time of 4 h, reaction temperature of 80 °C and n e p o x y n - N H 2 of 3/1, respectively. The XRD patterns showed the crystallinity of HBCC and H2ECC decreased due to the introduction of hydrophobic segments. The thermostability of HBCC and H2ECC was improved for the formation of heat-resistant stereo-complexed structures. The intermolecular hydrophobic interaction hindered the intermolecular mobility by increasing glass transition temperature of ca. 10 °C. Both HBCC and H2ECC have very low critical aggregation concentrations (HBCC: 0.66–1.56 g/L, H2ECC: 0.57–1.07 g/L) and moderate aggregate particle size, which is advantageous for utilization as a drug carrier. The curcumin loaded HBCC and H2ECC aggregates showed nontoxicity, meanwhile, HBCC and H2ECC showed good antibacterial activity against Staphylococcus aureus and Escherichia coli . As a result of these two favorable properties, HBCC and H2ECC could be used as curcumin nanocarriers as well as antibacterial agents.
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JOURNAL OF MOLECULAR LIQUIDS
·
2020
·
IF 5.065
Ye Gao,Teng Zhang,Changyou Yu,Peiyi Li,Ningning Tian,Songgu Wu
The crystal structure of 1,3-Di-o-tolylguanidine (DOTG) were investigated, as well as the thermodynamic properties about the solid-liquid phase equilibrium. The intermolecular interactions examined by Hirshfeld surface analysis demonstrate that the N-H···N and C-H···C interactions are dominant in the solid-state structure of DOTG. The solubility of DOTG in thirteen pure solvents (ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol , 2-butanol, 1-pentanol, propyl acetate , isopropyl acetate, acetone, butanone , acetonitrile , 1,4-dioxane) was measured by a gravimetric method from 283.15 K to 323.15 K at atmospheric pressure. According to the experimental results, the solubility of DOTG in all solvents increase with the increase of temperature. The determined solubility data were correlated using the Apelblat equation, λh equation, van't Hoff equation and the NRTL model. Additionally, the effects of solvent properties on the solubility of DOTG were discussed in terms of solvent polarity, hydrogen bond and cohesive energy density . Furthermore, the mixing thermodynamic properties of DOTG were studied in selected solvents based on the NRTL model, showing that the process of DOTG dissolving is spontaneous and entropy-driving.
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Environmental Technology & Innovation
·
2020
·
IF 3.356
Chao Zhu,Zarak Mahmood,Abdul Saboor Arshad,Jia Liu,Hongrui Ma
Wastewater treatment has become a major global issue due of undegradable pollutants. As toxic water pollutants , namely o-toluidine and p-toluidine are difficult to treat, this study uses the silicon rubber technology to treat them. A pair of modules having single tabular nonporous silicon rubber tube and HCl stripping solution were set up to extract o-toluidine and p-toluidine from high-saline wastewater. Reaction quotient ( Q C ) was calculated after every 12 h intervals to evaluate the equilibrium reaction. The effect of concentration, pH, temperature, ionic strength, and flow rate on the permeability (P) and removal efficiency ( η ) were investigated to illustrate the process parameters and mechanisms of recovery of both elements from wastewater. The results showed that the recovery efficiency was more than 96% with concentration of 2–10g/L. When pH of the extraction solution was 2 or less, the pollutant permeability efficiency was nearly 95%. Moreover, when the salting strength was over 10%, the recovery efficiency increased quickly to some extent. Permeability, which mainly influenced by membrane resistance and desorption rate, initially increased and then decreased when the water flow increased from 2 and 20 mL/min. Aging of silicon rubber tube was also studied with respect to salinity , temperature, and acidity. Acidity and temperature was found to have a significant effect on the tube, permeability increased with an increase in aging, and aging had a minor effect on the elastic properties of the silicon rubber tube. Absorption and diffusion of water in silicon rubber tubes decreased when salinity increased more than 10%, which increased separation of p-toluidine and water. Due to this, there is no need of desalination before membrane extraction in treatment of p-toluidine wastewater with high saline. Thus, this study demonstrates that membrane extraction is a highly energy-efficient process for the effective recovery of o-toluidine and p-toluidine from wastewater with high salinity.
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