查找使用阿拉丁产品的科研文献

An in-source stretched membrane inlet for on-line analysis of VOCs in water with single photon ionization TOFMS

Keyong Hou,Fanglong Li,Wendong Chen,Ping Chen,Yuanyuan Xie,Wuduo Zhao,Lei Hua,Kemei Pei,Haiyang Li

An in-source, stretched, hollow fiber membrane (HFM) inlet has been developed to improve the sensitivity of on-line time-of-flight mass spectrometry (TOFMS) with a vacuum ultraviolet (VUV) lamp based single photon ionization (SPI) source for the direct analysis of liquid samples. A 2-cm HFM was stretched to 8 cm in length, and placed in the ion source and directly under the VUV lamp window with a distance of 15 mm. Compared with the conventional flow-through configuration under the same experimental conditions, the signal intensities of selected volatile organic compounds (VOCs) of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), benzene, toluene and p-xylene were increased over 5-fold in magnitude, and the response time was shortened to one-third. The limits of detection (LOD) of MTBE, ETBE, benzene, toluene and p-xylene ranged from 0.25 to 1.3 μg L−1 with a measurement time of 60 s, and three orders of linear range were obtained with correlation coefficients of 0.9972–0.9992. The present results suggest that the in-source stretched HFM is a simple and effective way to increase the sensitivity and shorten response time of the membrane inlet, and we believe that it will also be beneficial to other types of on-line mass spectrometer for the on-line analysis of VOCs in water with a VUV lamp based SPI ion source.

Nanostructured lipid carriers enhance the bioavailability and brain cancer inhibitory efficacy of curcumin both in vitro and in vivo

Yuhui Chen,Lizhen Pan,Ming Jiang,Dong Li,Lingjing Jin

Gold nanorods as a theranostic platform for in vitro and in vivo imaging and photothermal therapy of inflammatory macrophages

Jinbao Qin,Zhiyou Peng,Bo Li,Kaichuang Ye,Yuxin Zhang,Fukang Yuan,Xinrui Yang,Lijia Huang,Junqing Hu,Xinwu Lu

Inflammatory macrophages play pivotal roles in the development of atherosclerosis. Theranostics, a promising approach for local imaging and photothermal therapy of inflammatory macrophages, has drawn increasing attention in biomedical research. In this study, gold nanorods (Au NRs) were synthesized, and their in vitro photothermal effects on the macrophage cell line (Ana-1 cells) under 808 nm near infrared reflection (NIR) were investigated by the CCK8 assay, calcein AM/PI staining, flow cytometry, transmission electron microscopy (TEM), silver staining and in vitro micro-computed tomography (CT) imaging. These Au NRs were then applied to an apolipoprotein E knockout (Apo E) mouse model to evaluate their effects on in vivo CT imaging and their effectiveness as for the subsequent photothermal therapy of macrophages in femoral artery restenosis under 808 nm laser irradiation. In vitro photothermal ablation treatment using Au NRs exhibited a significant cell-killing efficacy of macrophages, even at relatively low concentrations of Au NRs and low NIR powers. In addition, the in vivo results demonstrated that the Au NRs are effective for in vivo imaging and photothermal therapy of inflammatory macrophages in femoral artery restenosis. This study shows that Au nanorods are a promising theranostic platform for the diagnosis and photothermal therapy of inflammation-associated diseases.

Enhancement of Catalytic Activity in Epoxide Hydration by Increasing the Concentration of Cobalt(III)/Salen in Porous Polymer Catalysts

Zhifeng Dai,Qi Sun,Fang Chen,Shuxiang Pan,Liang Wang,Xiangju Meng,Jixue Li,Feng-Shou Xiao

Graphical Rational design : A porous organic polymer with a very high salen concentration is rationally synthesized from the self-polymerization of a salen-based monomer. After the loading of Co 3+ , the heterogeneous catalyst shows even better properties than the homogeneous version in the catalytic hydration of epoxides because of the enrichment of activated reactants. The rational design of catalytic materials from the reaction characteristics is expected to be a useful strategy to create highly efficient catalysts. Herein, according to a well-established reaction pathway of epoxide hydration catalyzed a dual-molecular system of Co 3+ /salen in which a high concentration of active sites is favorable to enhance the activity, we provide an alternative way to prepare a highly efficient heterogeneous catalyst with a high concentration of Co 3+ /salen from the polymerization of vinyl-functionalized salen monomers followed by the loading of Co 3+ species (Co 3+ /POL-salen). Co 3+ /POL-salen has a hierarchical porosity and an extraordinary hydrothermal stability. Importantly, catalytic tests in epoxide hydration demonstrate that Co 3+ /POL-salen affords excellent high activities, which are even better than those of the homogeneous version. This phenomenon is related to the very high concentration of Co 3+ /salen in the catalyst. In addition, this catalyst can be recycled readily because of its excellent hydrothermal stability.

Magnetic lanthanide oxide catalysts: An application and comparison in the heterogeneous catalytic ozonation of diethyl phthalate in aqueous solution

Junliang Wang,Yuanyang Lou,Chao Xu,Shuang Song,Weiping Liu

Catalytic oxidation with nano magnetic catalysts has the advantages of easy recovery, good stability and high activity. In this study, three nano magnetic lanthanide catalysts with a core–shell structure of Ce/SiO 2 @Fe 3 O 4 , La/SiO 2 @Fe 3 O 4 and Pr/SiO 2 @Fe 3 O 4 were prepared and characterized by Brunauer–Emmet–Teller, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectrum and vibrating sample magnetometer analysis. All catalysts have Fe 3 O 4 nanoparticles as cores, SiO 2 as the mid-layer, and CeO 2 , La 2 O 3, or Pr 6 O 11 as the outer layer, and have a good magnetic property. The catalyst activities followed the descending order of Pr/SiO 2 @Fe 3 O 4   >   La/SiO 2 @Fe 3 O 4   >   Ce/SiO 2 @Fe 3 O 4 upon the degradation of diethyl phthalate (DEP), and the catalytic ozonation process followed an OH reaction mechanism. The removal rate of DEP was small effected because of the presence of Cl − , and addition of sodium carbonate had no obviously influence. The initial mineralization rate had a positive relation with the hydroxyl groups and pH value at the zero charge point (pH pzc ) of the catalysts, but had no significant relation with the surface area of the catalysts. The catalysts were relatively effective and stable after 3 repeated uses, and the leaching out concentrations of Ce, La and Pr were 1.33   mg/L, 0.138   mg/L and 0.115   mg/L after a 90   min reaction.

Understanding the thermosensitivity of POEGA-based star polymers: LCST-type transition in water vs. UCST-type transition in ethanol

Lei Hou,Qijing Chen,Zesheng An,Peiyi Wu

The lower critical solution temperature (LCST) transition in water and the upper critical solution temperature (UCST) transition in ethanol of poly(oligo(ethylene glycol) acrylate) (POEGA)-based core cross-linked star (CCS) polymers have been investigated and compared by employing turbidity, dynamic light scattering (DLS), 1H NMR and FTIR measurements. Macroscopic phase transitions in water and in ethanol were observed to occur when passing through the transition temperature, as revealed by DLS and turbidity measurements. Analysis by IR indicated that the interactions between the polymer chains and solvent molecules in water are stronger than those in ethanol such that the CCS polymer arm chains in water adopt more extended conformations. Moreover, hydrophobic interaction among the aliphatic groups plays a predominant role in the LCST-type transition in water whereas weak solvation of the polymer chains results in the UCST-type transition in ethanol. Additionally, the LCST-type transition in water was observed to be much more abrupt and complete than the UCST-type transition in ethanol, as suggested by 1H NMR and IR at the molecular level. Finally, an abnormal “forced hydration” phenomenon was observed during the LCST transition upon heating. This study provides a detailed understanding of the subtle distinctions between the thermal transitions of CCS polymers in two commonly used solvents, which may be useful to guide future materials design for a wide range of applications.

A thin shell and “sunny shape” molecular imprinted fluorescence sensor in selective detection of trace level pesticides in river

Hongji Li,Xiao Wei,Yeqing Xu,Kai Lu,Yufeng Zhang,Yongsheng Yan,Chunxiang Li

This investigation presented a novel strategy for the preparation of hybrid structure silica/ZnO/molecularly imprinted polymers (SiO 2 /ZnO/MIPs) to fluorescence recognization and detection of the pyrethroids. Firstly, carboxylated SiO 2 nanoparticles (Si-NPs) and amino-functionalized ZnO quantum dots (QDs) were linked together by the function of amination under the assistance of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxy-5-pyrrolidinedione (NHS). Next, the “sunny shape” molecular imprinted polymers (MIPs) layers were anchored on the surface of SiO 2 /ZnO QDs by the technique of atom transfer radical polymerization (ATRP) and surface molecular imprinting. The resulting nanoparticles were characterized by TEM , FT-IR, fluorescence spectra and the adsorptive properties were detected by the UV–vis spectrophotometer. Through the results, the strategy shortened the preparation time and presented more rapid and sensitive detection performance than the traditional methods. The fluorescence detection results demonstrated this material owned special recognition property to the templates, which contributed that the fluorescence intensity decreased linearly with the variation of pyrethroids in the concentration range 1.0–80 μmol L −1 under the optimized conditions and the detection limit was 0.13 μmol L −1 . Moreover, the successful applications in practical samples indicated that the synthesis method in this investigation provided a novel way to the pyrethroids detection in river.

Role of Ethylene in the Biosynthetic Pathway of Related-aroma Volatiles Derived from Fatty Acids in Oriental Sweet Melon

Yan Li,Hongyan Qi,Yazhong Jin,Xiaobin Tian,Linlin Sui,Yan Qiu

The catabolism of fatty acid (FA) is regarded as a key pathway of aroma volatile compounds in oriental sweet melon (Cucumis melo var. makuwa). In our research, two cultivars of oriental sweet melon, Caihong7 and Tianbao, were employed to illuminate which step of the biosynthetic pathway of aroma compounds could be regulated by ethylene (ETH). The role of ETH in determining the profiles of straight-chain aroma volatile compounds, levels of FA as aroma precursors, activities of aroma-related enzymes derived from FA pathway, and expression patterns of key enzymes were investigated. Overall, exogenous application of ETH increased the production rates of endogenous ETH and levels of FA. Compared with control, the level of straight-chain esters, especially the acetate, hexanoate, and hexyl esters, was significantly increased by ETH, whereas the content of alcohol and aldehyde reduced. In addition, the metabolism of free FA included linoleic acid (LA), linolenic acid (LeA), and oleic acid (OA) appeared to be ETH-dependent. The activities of lipoxygenase (LOX), alcohol dehydrogenase (ADH), and alcohol acetyltransferase (AAT) as well as the expression patterns of Cm-ADH1, Cm-ADH2, Cm-AAT1, and Cm-AAT4 were positively regulated by ETH. In contrast, hydroperoxide lyase (HPL) and Cm-AAT2 and Cm-AAT3 seemed to be independent of ETH modulation. These results suggested that the dissimilation of FA included LA, LeA, and OA into the acetate, hexanoate, and hexyl esters mainly through ETH regulating the LOX pathway by enhancing the expression of particular members of aroma-related key enzyme gene families as well as the activities of dehydrogenation and esterification.

Aspartic acid racemization in dentin of the third molar for age estimation of the Chaoshan population in South China

Shisheng Chen,Yanyi Lv,Dian Wang,Xiaojun Yu

Aspartic acid racemization in teeth has been increasingly used to estimate chronological age with a considerably high accuracy in forensic practice. The Chaoshan population in South China is relatively isolated in geography, and has specific lifestyle and dietary inhibits. It is still unknown whether this method is suitable for this population. The aim of this study was to analyze the relationship between chronological age and the d / l aspartic acid ratio in dentin in the third molar tooth of the Chaoshan population. Fifty-eight non-carious third molar teeth (31 mandibles and 27 maxillae), from 58 living individuals of known age (24 males and 34 females), were retrieved. Dentin was extracted from these teeth. The d - and l -aspartic acids in dentins were separated and detected by high performance liquid chromatography (HPLC). Linear regression was performed between the d / l aspartic acid ratio of dentins and chronological age. Results showed that the correlation coefficient (r) was 0.969, and the mean absolute error (MAE) was 2.19 years, its standard deviation (SD) was ±1.53 years, indicating excellent correlation. There was no significant difference in racemization rates of dentin between sexes ( P   =   0.113, F   =   2.6), or between mandibles and maxillae ( P   =   0.964, F   =   0.000). Results indicate that the ratio of the d and l forms of aspartic acid of dentins, in the third molar, is closely correlated with chronological age, special lifestyle do no obviously affect the accuracy of the age estimations by aspartic acid racemization of the dentin in the third molar and that aspartic acid racemization in the third molar dentin can be used as an accurate method to estimate chronological age in the Chaoshan population in South China.

Rapid detection of five anesthetics in tilapias by in vivo solid phase microextraction coupling with gas chromatography-mass spectrometry

Shuyao Huang,Jianqiao Xu,Jiayi Wu,Haojia Hong,Guosheng Chen,Ruifen Jiang,Fang Zhu,Yuan Liu,Gangfeng Ouyang

The concentration of five rapidly metabolized anesthetics in living tilapias was determined in this study, by the presented method coupling in vivo solid phase microextraction (SPME) to gas chromatography-mass spectrometry (GC-MS), which was the first time that in vivo sampling method was adapted in detecting the anesthetic residue in the living aquatic product. The analytical performance of the developed method was evaluated in homogenized tilapia dorsal muscle, and the results demonstrated that the present method possessed low detection limits 1.7–9.4   ng   g −1 ), wide linear ranges (10 or 30–5000   ng   g −1 ), and satisfactory reproducibility (relative standard deviations no more than 8.1% and 10.8% for inter-fiber and intra-fiber assays, respectively). Standard curves were established in homogenized tilapia dorsal muscle for calibrating in vivo SPME in living tilapias. And the concentrations determined by in vivo SPME were close to those determined by the liquid extraction. By using the present method, one anesthetic residue was detected above the detection limit in tilapias from the local markets. Comparing to traditional methods, the present one exhibited superior time-efficiency and cost performance, as the extraction time was only ten minutes, which was short to successfully avoid the possible loss of analytes caused by elimination and sample storage. In addition, owing to the time-efficiency of the present method, the elimination of the anesthetics in tilapias was traced successfully in the laboratory.

Growth under elevated air temperature alters secondary metabolites in Robinia pseudoacacia L. seedlings in Cd- and Pb-contaminated soils

Y.H. Zhao,X. Jia,W.K. Wang,T. Liu,S.P. Huang,M.Y. Yang

Plant secondary metabolites play a pivotal role in growth regulation, antioxidant activity, pigment development, and other processes. As the global climate changes, increasing atmospheric temperatures and contamination of soil by heavy metals co-occur in natural ecosystems, which alters the pH of rhizosphere soil and influences the bioavailability and mobility of metals. Elevated temperatures in combination with heavy metals are expected to affect plant secondary metabolites, but this issue has not been extensively examined. Here, we investigated secondary metabolites in Robinia pseudoacacia seedlings exposed to elevated temperatures using a passive warming device in combination with Cd- and Pb-contaminated soils. Heavy metals significantly stimulated the accumulation of saponins, phenolic compounds , and flavonoids in leaves and stems; alkaloid compounds increased in leaves and decreased in stems, and condensed tannins fluctuated. Elevated temperatures, alone and in combination with Cd and Pb, caused increases in secondary metabolites in the plant tissues. Phenolic compounds showed the greatest changes among the secondary metabolites and significant interactive effects of temperature and metals were observed. These results suggest that slightly elevated temperature could enhance protective and defense mechanisms of Robinia pseudoacacia seedlings exposed to heavy metals by stimulating the production of secondary metabolites.

Multiple resistance to ACCase and ALS-inhibiting herbicides in Beckmannia syzigachne (Steud.) Fernald without mutations in the target enzymes

Wei Li,Lele Zhang,Ning Zhao,Wenlei Guo,Weitang Liu,Lingxu Li,Jinxin Wang

ABSTRACT American slough grass ( Beckmannia syzigachne (Steud.( Fernald) is a worldwide weed and is widely distributed in rice-wheat rotations in China. Fenoxaprop- P -ethyl and mesosulfuron-methyl are two major herbicides used to control B. syzigachne . Resistance has evolved in B. syzigachne under continuous selective pressure from herbicides. This study aimed to establish the cross-resistance pattern of a resistant population and explore the potential non-target-site based resistance mechanisms of B. syzigachne . Sequencing of target enzyme genes (acetyl coenzyme A carboxylase (ACCase( and acetolactate synthase (ALS() revealed that there were no resistance-endowing amino acid substitutions in the resistant B. syzigachne population (R F1 ) compared with the sensitive population (S F1 ), and obtained the purified materials. Furthermore, piperonyl butoxide (PBO) and malathion showed synergistic effects with fenoxaprop- P -ethyl and mesosulfuron-methyl respectively in R F1 . Therefore, we speculate that the resistance observed in B. syzigachne was related with metabolic, mostly involving the cytochrome P450 enzymes. Cross resistance patterns showed that the purified resistant B. syzigachne produce high resistance to fenoxaprop- P -ethyl and pyroxsulam; intermediate resistance to flucarbazone-sodium; low resistance to quizalofop- P -ethyl, clodinafop-propargyl, sethoxydim and mesosulfuron-methyl; sensitive to clethodim pinoxaden and isoproturon. Key words:  Herbicide resistance; metabolic resistance; P450 inhibitors; target enzymes sequencing.