MACROMOLECULES
·
2011
·
IF 4.838
Yanwu Zhou,Junpo He,Changxi Li,Linxiang Hong,Yuliang Yang
The thermal decomposition of different classes of RAFT/MADIX agents, namely dithioesters, trithiocarbonates, xanthates, and dithiocarbamates, were investigated through heating in solution. It was found that the decomposition behavior is complicated interplay of the effects of stabilizing Z-group and leaving R-group. The mechanism of the decomposition is mainly through three pathways, i.e., β-elimination, α-elimination, and homolysis of dithiocarbamate (particularly for universal RAFT agent). The most important pathway is the β-elimination of thiocarbonylthio compounds possessing β-hydrogen, leading to the formation unsaturated species. For the leaving group containing solely α-hydrogen, such as benzyl, α-elimination takes place, resulting in the formation of (E)-stilbene through a carbene intermediate. Homolysis occurs specifically in the case of a universal RAFT agent, in which a thiocarbonyl radical and an alkylthio radical are generated, finally forming thiolactone through a radical process. The stabilities of the RAFT/MADIX agents are investigated by measuring the apparent kinetics and activation energy of the thermal decomposition reactions. Both Z-group and R-group influence the stability of the agents through electronic and steric effects. Lone pair electron donating heteroatoms of Z-group show a remarkable stabilizing effect while electron withdrawing substituents, either in Z- or R-group, tends to destabilize the agent. In addition, bulkier or more β-hydrogens result in faster decomposition rate or lower decomposition temperature. Thus, the stability of the RAFT/MAIDX agents decreases in the order where R is (with identical Z = phenyl) −CH2Ph (5) > −PS (PS-RAFT 15) > −C(Me)HPh (2) > −C(Me)2C(═O)OC2H5 (7) > −C(Me)2Ph(1) > −PMMA (PMMA-RAFT 16) > −C(Me)2CN (6). For those possessing identical leaving group such as 1-phenylethyl, the stability decreases in the order of O-ethyl (11) > –N(CH2CH3)2 (13) > –SCH(CH3)Ph (8) > −Ph (2) > −CH2Ph (4) > −PhNO2 (3). These results consort with the chain transfer acitivities measured by the CSIRO group and agree well with the ab initio theoretical results by Coote. In addition, the difference between thermal stabilities of the universal RAFT agents at neutral and protonated states has also been demonstrated.
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS
·
2023
·
IF 4.9
Jiuheng Ruan,Chao Liu,Haoyuan Song,Ting Zhong,Peng Quan,Liang Fang
Skin pharmacokinetics (SPK) of permeation enhancers can answer the question of why enhancement effects different at the kinetic level. Herein, SPK of permeation enhancers were classified into two categories, namely, lateral elimination (elimination to surrounding stratum corneum (SC)) and longitudinal elimination (elimination to deep epidermal (EP)). They were evaluated with a specific parameter for permeation enhancers, diffusion ratio ( DR SC-EP ), according to results of tissue-distribution test, molecular dynamic (MD) simulation, and confocal laser scanning microscopy (CLSM). The linear relationship between k e-enahcer and Δ C max-drug ( R 2 = 0.92), MRT enhancer and Δ T max-drug ( R 2 = 0.97), AUC t - enhancer and Δ AUC t-drug ( R 2 = 0.90) suggesting that SPK of permeation enhancers precisely controlled dynamic process of drug permeation in vivo . The molecular mechanisms of the dynamic effect of SPK process on drug transdermal behaviors were characterized by modulated-temperature differential scanning calorimetry (MTDSC), dielectric spectroscopy , small-angle X-ray scattering (SAXS), solid-state NMR. Permeation enhancers with high molecular weight ( M.W. ) and high polar surface area ( P.S.A. ) had good compatibility and strong interaction strength with SC, leading their lateral-elimination behavior, causing their low DR SC-EP and resulting in low k e-enhancer , long MRT enhancer , and large AUC t-enhancer . Consequently, skin barrier can be rapidly opened fast and to a great extent. In summary, compared with SPK of permeation enhancers with longitudinal elimination, SPK of permeation enhancers with lateral elimination can enable more sustainable and greater drug permeation. The information about SPK of permeation enhancers offered a criterion to estimate its permeation-enhancement effect on the drug and its subsequent application in transdermal formulations.
研究领域:
药理学
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生物医学工程
·
药物递送系统
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FOOD CHEMISTRY
·
2019
·
IF 5.399
Jiaojiao Yin,Li Wang,Yuanyuan Chen,Dianfu Zhang,Abeer M. Hegazy,Xuezhen Zhang
In this study, bighead carp ( Aristichthys nobilis ) were exposed to waterborne Cr 6+ of 0.01, 0.1, 1 and 5 mg/L for 14 days and subsequently transferred to clean water for another 14 days. The Cr 6+ contents in some edible parts, such as dorsal muscle, ventral muscle and head were detected. The Cr 6+ concentrations in the three parts were in the order of: head > ventral muscle > dorsal muscle with significant increase during exposure period and remarkable decrease when kept at clean water during depuration stage. The head contained higher fat than that of muscle and the Cr 6+ levels of these parts showed significantly positive correlation with fat content, however, the Cr 6+ contents in the separated fat were extremely low. The Cr 6+ levels determined in tissues can tell a real story rather than the correlation coefficient. Fish head poses a higher potential health risk than muscle due to heavy metals pollution.
研究领域:
环境科学
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Zhuang Ma,Jie Li,Yayun Bai,Yufei Zhang,Haonan Sun,Xinge Zhang
A broad spectrum of microbial persistent infections is associated with bacterial biofilm which is difficult to be eliminated. In the clinic, diagnosis of biofilm-associated infections is heavily dependent on culturing methods which are difficult to identify pathogenic bacterial infection in vivo . Here, a facile bioreponsive nanoplatform consisting of spiropyran and galactose was developed for selectively imaging and eliminating the biofilm in situ. The nanoplatform could specially bind to bacteria through carbohydrate-protein interaction and rapidly respond to bacterial infection-microenvironment, finally imaging and eliminating biofilm. Importantly, the bioinspired nanoplatform is highly selective towards bacterial cells rather than mammalian cells with low toxicity against A549 cells. Collectively, this multifunctional nanoplatform as an imaging and dispersing biofilm agent provides promising insights for the development of the new treatment of biofilm-associated infections.
研究领域:
微生物学
·
医学影像学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Tingwei Wang,Hanpeng Liu,Sam Toan,Zhao Sun,Zhiqiang Sun
Deoxygenation-based biomass gasification provides a feasible solution for the effective utilization of biomass and value-added syngas production. However, the behavior of bio-oil formation during the pyrolysis stage and the characteristics of tar abatement at the gasification stage with applied deoxidizer still require exploration. Thus, this study investigates the effects of different deoxidizer/biomass (D/B) mass ratios, pyrolysis-gasification temperatures, and water-injection velocities on the composition and yield of bio-oil and tar-elimination law. The techniques of 2D HSQC nuclear magnetic resonance, attenuated total reflectance, gel permeation chromatography, and gas chromatography-mass spectrometer are used to investigate the formation behavior and evolution law of the bio-oil produced. The results indicate that the addition of the deoxidizer not only improves the quality and yield of syngas but promotes the deoxygenation of oxygen-containing bio-oil by donating electrons. Specifically, the phenolic compounds decreased by 12.4% under D/B = 0.3 as compared with D/B = 0. The results also confirm the promoting effect of tar elimination via reforming and cracking by Fe and CaO, respectively: Tar production during the gasification stage decreased by 54% under D/B = 0.3, as compared with non-deoxygenation. This study demonstrates the superiority of iron-calcium-based deoxidizer in bio-oil deoxygenation and tar elimination, which will promote the development of deoxygenation-based bio-oil and syngas poly-generation.
研究领域:
能源与燃料
·
环境科学
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2025
·
IF 2.9
Shuyan Liu,Xiuyu Du,Kuan Ji,Lili Lv,Yu Zhou
Ionic liquids (ILs) are highly effective entrainers for extractive distillation of azeotropes, owing to their unique physicochemical properties. However, the intrinsic molecular mechanisms underlying the role of ILs in azeotropic separation process remain insufficiently understood. To investigate the intrinsic causes of the azeotropy elimination by ILs, the study focused on the v(O−D) region of the ethanol employing both experimental and theoretical methods to investigate the microstructural properties of the ethyl propionate (EP)−ethanol azeotrope before and after separation by the 1-hexyl-3-methylimidazole acetate (HMIMOAc). The key findings are as follows: (1) The interaction between HMIMOAc and ethanol issignificantly stronger than that between EP and ethanol. (2) The interaction between [OAc]− in HMIMOAc and ethanol plays a critical role in eliminating the azeotropy. (3) Ethanol self-aggregates, EP−ethanol interaction complexes, and HMIMOAc−ethanol interaction complexes, were identified andcharacterized using excess spectroscopy and quantum chemical calculations.
研究领域:
化学工程
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物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chemical Science
·
2018
·Vol. 9
·期 14
·3426-3437
·
IF 9.063
Xinyu Li,Zhi-Jian Zhao,Liang Zeng,Jiubing Zhao,Hao Tian,Sai Chen,Kang Li,Sier Sang,Jinlong Gong
La2O3 exhibits good performance for various catalytic applications, such as oxidative coupling of methane (OCM) and dry reforming of methane (DRM), during which coke formation may lead to the deactivation of catalysts. Typically, the reaction between CO2 adsorbed on La2O3 and coke is the rate-determining step of the coke elimination process. This paper describes the influence of Ce addition on the CO2 adsorption and activation over La2O3. Combined with in situ and ex situ characterization and density functional theory (DFT) calculation, we show that Ce addition promotes the formation of bidentate carbonate on La2O3via tuning CO2 adsorption energy. In addition, Ce addition adjusts the ratio of bidentate/monodentate carbonate, and affects the ratio of hexagonal/monoclinic La2O2CO3 on the binary oxides. DRM is used as a probe reaction to examine the coke elimination performance of Ce–La binary oxide. It is found that when the Ce/La ratio reaches the optimal value (0.15), Ce–La binary oxide has the highest CO2 adsorption energy and predominantly promotes the formation of bidentate carbonate, and hence possesses the highest basicity above 700 °C and finally exhibits the best coke elimination performance.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
Minerals
·
2021
·Vol. 11
·期 6
·599
·
IF 2.644
Yanping Niu,Ya Li,Haoran Sun,Chuanyao Sun,Wanzhong Yin,Hongfeng Xu
Ferric ions produced during grinding influence the flotation separation between kyanite and quartz adversely. In this study, citric acid was used as a regulator to eliminate the effect of ferric ions on the separation of kyanite from quartz with sodium oleate (NaOL) as a collector. The microflotation test results indicated that the quartz was selectively activated by FeCl3and maintained significant quartz recovery. However, the citric acid could selectively eliminate the effect of ferric ions on the quartz and minimally influenced the kyanite. Contact angle tests demonstrated that FeCl3significantly increased the interaction between NaOL and quartz, resulting in the high hydrophobicity of quartz, and the addition of citric acid made the quartz surface hydrophilic again but slightly influenced the kyanite. Fourier-transform infrared spectroscopy showed that FeCl3facilitated NaOL adsorption onto the quartz surface, and the addition of citric acid eliminated the activation of FeCl3on the quartz, resulting in the nonadsorption of NaOL onto the quartz surface. However, the FeCl3and citric acid exhibited a negligible effect on NaOL adsorption onto the kyanite surface. X-ray photoelectron spectroscopy analysis indicated that the citric acid eliminated FeCl3activation on the quartz.Keywords:kyanite;quartz;citric acid;ferric ion;selective elimination
研究领域:
矿物学
·
浮选化学
✓ 已验证
产品关联
DOI
高影响因子
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2022
·
IF 7.129
Shengliang Zhao,Xuandi Lai,Feiyan Liu,Liqiong Chen
Hexavalent chromium (Cr(VI)) determination is of great importance to the public health because of its extensive sources and high toxicity. However, interference from non-target ions and complex matrix remains challenges for Cr(VI) detection. In this work, we constructed a novel sensing system for high selectivity detection of Cr(VI), which is composed of strong emitting carbon dots (CE-CDs) and a specific masking agent. The detection conditions, anti-interference capability and the sensing and masking mechanisms of CE-CDs-based sensing method were systematically investigated. The results revealed that the optimal detection conditions included pH 4–10, reaction time 180 s and CE-CDs concentration 18 mg/L. Under optimal conditions, the linear range of the method was up to 500 µm, and the detection limit was as low as 23 nM. In addition, the interference of Hg(II) can be accurately eliminated by using DMPS, an effective masking agent. During the sensing process, inner filter effect and ion-molecular interaction between Cr(VI) and CE-CDs accounted for the fluorescence quenching mechanism, while the efficient masking was attributed to the strong coordination interaction between Hg(II) and DMPS. Most notably, this method had broad applicability, even for the trace detection of Cr(VI) in colored leather with complex matrix. These findings indicate that this approach is expected to open up new avenues for Cr(VI) detection.
研究领域:
环境科学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Analytical Methods
·
2017
·Vol. 9
·期 30
·4471-4475
·
IF 1.9
L. F. Tian,D. S. Zou,Y. C. Dai,L. L. Wang,W. Gao
Quantification of chromium in V–Cr–Ti ternary alloys, used as candidate structural materials for fusion reactors, is essential in view of its significant effect on the properties of these vanadium-based alloys. Various methods have already been used for the determination of chromium in common alloys, but most of these methods are based on complicated and expensive instruments or suffer from the serious matrix interference of vanadium. In this study, a simple, rapid and accurate spectrophotometric method was developed for the determination of chromium in V–Cr–Ti alloys without any prior separation and chromogenic agent. The alloy samples were dissolved in diluted sulphuric acid and concentrated nitric acid, and chromium was oxidized with persulphate in the presence of Ag(I) ions as a catalyst. After alkalization of the solution with sodium hydrate, greenish-yellow coloured chromate (CrO42−) ions were formed in the alkaline solution and had a maximum absorption peak at 374 nm. Beer's law was obeyed in the range of 0.15–12.0 μg mL−1 Cr(VI) at 374 nm and the molar absorptivity was 4.8 × 103 L mol−1 cm−1. All the variables were studied in order to optimize the analytical conditions. Vanadium and titanium seriously interfered with the determination of Cr(VI) and their interference can be eliminated by addition of ammonium tartrate. The proposed method is simple, fast, accurate and of low cost, and has been satisfactorily used for the determination of chromium in V–Cr–Ti alloys. The results are in good agreement with data given by inductively coupled plasma optical emission spectrometry (ICP-OES) and the relative standard deviation is found to be lower than 0.4%.
研究领域:
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Jiamin Zhou,Shengduo Xu,Yi Shuai,Qiang Sun,Huangshui Ma,Chao Wang,Haijuan Wu,Shanshan Tan,Zegao Wang,Lei Yang
Broadband photodetectors that can decipher the wavelength (λ) and intensity (I) of an unknown incident light are urgently demanded. Photothermoelectric (PTE) detectors can achieve ultrabroadband photodetection surpassing the bandgap limitation; however, their practical application is severely hampered by the lack of deciphering strategy. In this work, we report a variable elimination method to decipher λ and I of the incident lights based on an integrated Ag2Se film-based PTE detector. Nanostructured Ag2Se films with controlled thickness are synthesized using an ion sputtering of Ag and a room-temperature selenization method and then assembled into a detector. Under identical illumination, Ag2Se films of different thicknesses produce varying output photothermal voltages, influenced by factors including λ. By establishing a direct relationship between the photothermal voltage and the absorption of Ag2Se films of varied thickness, we successfully eliminate variables independent of λ, thus determining λ. Subsequently, I is determined by the calibrated responsivity relationship using obtained λ. Our PTE detector achieves a broadband spectrum from 400 to 950 nm and high accuracy, with deviations as low as ∼2.63 and ∼0.53% for deciphered λ and I, respectively. This method allows for self-powered broadband decipherable photodetection without a complex device architecture or computational assistance, which could boost the research enthusiasm and promote the commercialization of PTE broadband detectors.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Bing Li,Weiquan Li,Qian Zuo,Weizhao Yin,Ping Li,Jinhua Wu
A weak electric field (WEF, 2 mA cm −2 ) was employed to promote Fe(III)/Fe(II) cycle on goethite-impregnated activated carbon (FeOOH@AC) filled in a continuous-flow column for enhanced Cr(VI) elimination from water. Surficial analysis and Cr species distribution showed that α-FeOOH of 0.2–1 μm was successfully synthesized and evenly loaded onto AC. Electron transfer from WEF to α-FeOOH was facilitated with AC as electron shuttles, thereby boosting Fe(III) reduction in the α-FeOOH. The generated Fe(II) reduced Cr(VI) and the resultant Cr(III) subsequently precipitated with OH − and Fe(III) to form Cr(OH) 3 and (Cr χ Fe 1-χ )(OH) 3 . Therefore, the WEF-FeOOH@AC column exhibited a much lower Cr(VI) migration rate of 0.0018 cm PV −1 in comparison with 0.0037 cm PV −1 of the FeOOH@AC column, equal to 104 % higher Cr(VI) elimination capacity and 90 % longer column service life-span. Additionally, under different Cr(VI) loadings by varying either seepage velocities or influent Cr(VI) concentrations, the WEF-FeOOH@AC column maintained 1.0–1.5 folds higher Cr(VI) elimination and 0.9–1.4 folds longer longevity than those of the FeOOH@AC column owing to the interaction between FeOOH@AC and WEF. Our research demonstrated that WEF-FeOOH@AC was a potential method to promote Cr(VI) elimination from water and offer an effective strategy to facilitate Fe(III)/Fe(II) cycle in iron oxides .
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）