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Now showing items 81 - 96 of 148

  • Synthesis of Cyclic Carbonate Catalyzed by DBU Derived Basic Ionic Liquids

    Li, Wei   Cheng, Weiguo   Yang, Xia   Su, Qian   Dong, Lihui   Zhang, Pan   Yi, Yunan   Li, Bin   Zhang, Suojiang  

    In this work, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]-5-nonene (DBN), and imidazole (MIM)-derived bromide ionic liquids (ILs) were synthesized and used to catalyze the cycloaddition reactions of carbon dioxide (CO2) with several kinds of epoxides to form cyclic carbonates. The DBU derived bromide ionic liquid system was found to have the best catalytic activity among all the tested ILs. The influences of reaction conditions (including temperature, pressure and reaction time) on the reaction of CO2 to propylene oxide (PO) were studied to show the best conditions of 120 degrees C, 1 MPa, 2.5 h catalyzed by 2 mol% DBU-derived bromide ionic liquid, with the conversion of PO and the selectivity of propylene carbonate (PC) reaching 99% and 99%, respectively. Under the optimum reaction conditions, the ionic liquid system could be reused at least five times without decrease in selectivity and conversion. NMR spectroscopy and DFT calculations were used to reveal the hydrogen-bond interaction between ionic liquids and reagent, based on which the reaction mechanism was proposed.
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  • Increased serum ferritin levels are independently associated with carotid atherosclerosis in women

    Xu, Haiyan   Song, Yanqi   Xu, Jing   Gu, Yeqing   Zhang, Qing   Liu, Li   Meng, Ge   Wu, Hongmei   Xia, Yang   Bao, Xue   Shi, Hongbin   Su, Qian   Fang, Liyun   Yu, Fei   Yang, Huijun   Sun, Shaomei   Wang, Xing   Zhou, Ming   Jia, Qiyu   Wang, Guolin   Song, Kun   Wu, Yuntang   Sun, Zhong   Niu, Kaijun  

    Previous studies have supported the theory that there is a positive association between ferritin and carotid atherosclerosis in Western people. Diet plays an important role in determining serum ferritin concentration. Asian dietary patterns are different from Western dietary patterns, implying that there may be a difference in the association of ferritin with carotid atherosclerosis between Asian and Western people. However, few studies focus on the association between ferritin and carotid atherosclerosis among Asians. The aim of this study was to investigate how serum ferritin levels are associated with carotid atherosclerosis in an Asian adult population. A cross-sectional assessment was performed in 8302 adults in Tianjin, China. Carotid intima-media thickness (IMT) and plaques were assessed using ultrasonography, and serum ferritin was measured using the protein chip-chemiluminescence method. Multiple logistic regression analysis was used to examine the association between quartiles of serum ferritin concentration and carotid atherosclerosis. In the present study, the overall prevalence of IMT and carotid plaques in participants is 29.2 and 22.7%, respectively. In women, after adjustments for potentially confounding factors, the OR of IMT and carotid plaques by increasing serum ferritin quartiles were 1.00, 1.39 (95% CI 0.98-1.99), 1.39 (95% CI 0.99-1.97), 1.81 (95% CI 1.30-2.55) (P-for (trend)< 0.001) and 1.00, 1.24 (95% CI 0.89-1.73), 1.18 (95% CI 0.85-1.65), 1.59 (95% CI 1.15-2.20) (Pfor trend< 0.01), respectively. However, no association was found between serum ferritin and carotid atherosclerosis in men. The study demonstrated that increased serum ferritin levels are independently associated with IMT and carotid plaques in Asian women but not in Asian men.
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  • A review of loop heat pipes for aircraft anti-icing applications

    Su, Qian   Chang, Shinan   Zhao, Yuanyuan   Zheng, Haikun   Dang, Chaobin  

    Loop heat pipes (LHPs) are highly efficient two-phase heat transfer devices with the ability to transport significant amounts of heat over long distances. Owing to the increasing demand of anti-icing applications in aircraft, certain investigations regarding LHP anti-icing have been successfully conducted, which verified the anti-icing capacity and feasibility of loop heat pipe ice protection system (LHPIPS). In this work, we will conduct a deep analysis on the LHP application to aircraft anti-icing. After a brief introduction of the historical application background and application environment of the LHPIPS, a detailed description of its fundamental design will be elucidated, followed by a series of optimization strategies, including the graphene-coating integration technology, the adoption of bidisperse wicks, the introduction of nanofluids, and the use of double compensation chamber loop heat pipe (DCCLHP). We present the additional points that require further study and that could be further optimized for the development of the LHPIPS. This work contributes to a thorough understanding of the novel and promising LHPIPS, as well as guides its future designs and applications. (C) 2017 Elsevier Ltd. All rights reserved.
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  • Facile preparation of CoS2 nanoparticles embedded into polyaniline with tunable electromagnetic wave absorption performance

    Ji, Ying   Mu, Congpu   Wang, Bochong   Su, Qian   Xiang, Jianyong   Nie, Anmin   Cheng, Dachuan   Liu, Pengliang   Wen, Fusheng  

    Electromagnetic wave absorption has attracted wide attention due to electromagnetic wave pollution and radiation. The dielectric loss coating magnetic nanoparticles structure has a significant influence on electromagnetic wave absorption properties. In this manuscript, magnetic nanoparticles (CoS2) coated polyaniline (PANI) are synthesized via a facile and simple two-step strategy (a microwave assisted hydrothermal reaction followed an in-situ free radical chemical oxidative polymerization). The CoS2 nanoparticles are coated by PANI which is used as the matrix of electron conduction during converting electromagnetic energy into thermal energy. The electromagnetic wave absorption properties of PANI@CoS2 nanocomposites can be adjusted by changing the mass ratios of CoS2 and PANI. Compared with that of CoS2 nanoparticles or PANI, the electromagnetic wave absorption properties of PANI@CoS2 nanocomposites were significantly enhanced due to impedance matching and dielectric loss. When the mass ratio of PANI and CoS2 is 1:3, this nanocomposite exhibits excellent electromagnetic wave absorption. The maximum reflection loss can reach to -54.6 dB at electromagnetic wave frequency of 12.1 GHz and effective absorbing bandwidth is 4.76 GHz ranging from 9.63 to 14.39 GHz under corresponding nanocomposites thickness of 2.1 mm. Hence, PANI@CoS2 nanocomposites have potential application in electromagnetic wave absorption.
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  • Extracellular expression of a novel ss-agarase from Microbulbifer sp Q7,isolated from the gut of sea cucumber

    Su, Qian   Jin, Tianyi   Yu, Yuan   Yang, Min   Mou, Haijin   Li, Li  

    A novel endo-type ss-agarase was cloned from an agar-degrading bacterium, Microbulbifer sp. Q7 (CGMCC No. 14061), that was isolated from sea cucumber gut. The agarase-encoding gene, ID2563, consisted of 1800 bp that encoded a 599-residue protein with a signal peptide of 19 amino acids. Sequence analysis suggested that the agarase belongs to the GH16 family. The agarase was expressed in Escherichia coli with a total activity of 4.99 U/mL in fermentation medium. The extracellular enzyme activity accounted for 65.73% of the total activity, which indicated that the agarase can be extracellularly secreted using the wild-type signal peptide from Microbulbifer sp. Q7. The agarase exhibited maximal activity at approximately 40 degrees C and pH 6.0. It was stable between pH 6.0 and pH 9.0, which was a much wider range than most of the reported agarases. The agarase was sensitive to some metal ions (Cu2+, Zn2+ and Fe3+), but was resistant to urea and SDS. The agarase hydrolyzed ss-1,4-glycosidic linkages of agarose, primarily yielding neoagarotetraose and neoagarohexaose as the final products. These indicate that this recombinant agarase can be an effective tool for the preparing functional neoagaro-oligosaccharides.
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  • Hypoxia stimulates proliferation of rat neural stem/progenitor cells by regulating mir-21:an in vitro study

    Chen, Rui   Liu, Yanmei   Su, Qian   Yang, Yang   Wang, Li   Ma, Shuyun   Yan, Jiajia   Xue, Fangfang   Wang, Jianjun  

    Neural stem/progenitor cells (NSPCs) reside not only in the developing brain, but also in the adult brain within specialized microenvironments that regulate their function. In vitro and in vivo studies have revealed strong regulatory links between hypoxic/ischemic insults and activation of NSCPs. However, the underlying mechanisms of this activation remain unclear. In this study, we found that cell proliferation is promoted by hypoxia, and accompanied by increasing expression of miR-21 in cultured rat NSPCs. Moreover, qRT-PCR analysis indicated that expression of miR-21 increases in a time-dependent manner. 5-Bromo-2-deoxyUridine (BrdU) staining and flow cytometry showed that overexpression of miR-21 further promoted proliferation of NSPCs in the presence of hypoxia. Knocking down of miR-21 partially abolished the proliferative effect of hypoxia treatment on cell proliferation. Western blot demonstrated that overexpression of miR-21 enhanced expression of cyclin D1, while knock down of miR-21 suppressed cyclin D1 expression under hypoxic conditions. Furthermore, overexpression of miR-21 also increased levels of p-AKT. These results demonstrate that miR-21 plays a role in regulating the proliferation of cultured rat NSPCs undergoing hypoxia, and the activation of the PI-3-K signaling pathway might be one of the underlying mechanisms. These findings prompt a molecular study investigating potential mechanisms for stem cell treatment of cerebral ischemia.
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  • The Impact and Mechanism of Methylated Metabotropic Glutamate Receptors 1 and 5 in the Hippocampus on Depression-Like Behavior in Prenatal Stress Offspring Rats

    Lin, Tianwei   Dang, Shaokang   Su, Qian   Zhang, Huiping   Zhang, Junli   Zhang, Lin   Zhang, Xiaoxiao   Lu, Yong   Li, Hui   Zhu, Zhongliang  

    An increasing number of epidemiological investigations and animal models research suggest that prenatal stress (PS) could cause depression-like behavior in the offspring, which is sex specific. However, the underlying mechanisms remain to be elucidated. This study is to investigate the promoter methylation of metabotropic glutamate receptor 1 (mGluR1) and metabotropic Glutamate Receptor 5 (mGluR5) gene modification on PS induced depression-like behavior in offspring rats (OR). PS models were established, with or without 5-aza-2-deoxycytidine (5-azaD, decitabine) treatment. Animal behavior was assessed by the sucrose preference test (SPT), forced swimming test (FST), and open field test (OFT). The mRNA and protein expression levels of mGluR1 and mGluR5 in the hippocampus of offspring were detected with quantitative real-time PCR and Western blot analysis, respectively. The promoter methylation in the hippocampus of mGluR1 and mGluR5 OR were also analyzed. SPT showed significantly reduced sucrose preference in PS induced OR. FST showed significantly prolonged immobility time in PS induced OR. OFT showed significantly reduced central residence time in PS induced OR and no significantly influence in rearing as well as in frequency of micturition. Moreover, the mRNA, protein expression levels, and gene promoter methylation level of mGluR1 and mGluR5 in the hippocampus were significantly increased in the PS induced male OR, while no significantly influence in the PS induced female OR. Furthermore, the PS induced effects in male OR could be reversed by the microinjection of 5-azaD. In conclusion, our results showed that the promoter methylation of mGluR1 and mGluR5 gene modification is only involved in PS induced depression-like behavior in male OR in a sex-specific manner. These findings might contribute to the understanding of the disease pathogenesis and clinical treatment in future.
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  • The association between immunoglobulin concentrations and prediabetes prevalence in a large Chinese cohort

    Wang, Honglei   Song, Yanqi   Sun, Shaomei   Gao, Li   Liu, Li   Meng, Ge   Wu, Hongmei   Xia, Yang   Bao, Xue   Gu, Yeqing   Shi, Hongbin   Su, Qian   Fang, Liyun   Yang, Huijun   Wang, Xing   Zhou, Ming   Jia, Qiyu   Song, Kun   Zhang, Qing   Niu, Kaijun  

    Aims. Prediabetes has received public attention owing to the increasing prevalence worldwide. Mounting evidence has indicated that inflammation directly contributed to the etiology of glucose metabolism disorders. Although immunoglobulins play a crucial role in immune responses, little research has been done on the link between immunoglobulins and prediabetes in adults. Hence, the aim of the present study was to explore the associations between immunoglobulins levels and prevalence of prediabetes in a general adult population. Methods. A cross-sectional study was conducted among 8856 adults (mean standard deviation age: 48.4 +/- 10.7 years) in Tianjin, China. The serum immunoglobulins concentrations were measured by the immunonephelometric technique. Prediabetes was diagnosed using the following parameters in accordance with the American Diabetes Association: fasting plasma glucose, postprandial glucose and glycosylated hemoglobin. The associations between concentrations of immunoglobulins and the prevalence of prediabetes were assessed using multiple logistic regression models. Results. Overall, the prevalence of prediabetes was 37.4% (3311/8856). After controlling for confounders, compared with the lowest quintile, the odds ratios (95% confidence interval) of prediabetes for the highest quintile of immunoglobulins (immunoglobulin G, immunoglobulin E, immunoglobulin M and immunoglobulin A) were as follows: 1.06 (0.91-1.23), 1.31 (1.13-1.52), 0.86 (0.74-1.01), and 1.19 (1.03-1.38) (P for trend were 0.35, <0.0001, 0.04 and 0.02), respectively. Conclusions. Elevated immunoglobulin E and immunoglobulin A levels were independently and positively associated with prediabetes prevalence. There was also a trending association between immunoglobulin M concentrations and prediabetes prevalence. Further studies are necessary to clarify if there is a causal association of immunoglobulins in prediabetes or if they reflect early immunologic disturbances in these patients. 2017 Elsevier Inc. All rights reserved.
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  • Diastolic Blood Pressure Rises with the Exacerbation of Obstructive Sleep Apnea in Males

    Hu, Wei   Jin, Xian   Chen, Chengjun   Zhang, Peng   Li, Dandan   Su, Qian   Yin, Guizhi   Hang, Yanwen  

    ObjectiveTo characterize the association pattern between blood pressure (BP), metabolism changes, and obstructive sleep apnea (OSA) severity within male OSA patients. MethodsThe association between systolic BP (SBP), diastolic BP (DBP), glucose, lipids, apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and arousal index (ArI) was evaluated after adjustment for BMI and waist circumference/hip circumference ratio (WHR) in 1,370 male OSA patients. ResultsIn the multiple linear regression models using SBP as an independent variable, SBP did not associate with the increase of any OSA indexes. BMI and glucose positively associated with AHI, ODI, and ArI elevation. WHR was also positively associated with increasing AHI and ODI. Total cholesterol levels increased with ODI and ArI increases. Triglyceride was associated with ArI. In the multiple linear regression models using DBP as an independent variable, DBP associated universally with AHI, ODI, and ArI with stable coefficients ranging from 0.19 to 0.20. The remaining independent variables were associated with AHI, ODI, and ArI with a similar trend to the models including SBP as an independent variable. ConclusionsApnea-hypopnea, hypoxemia, and arousal changed glycometabolism, fat metabolism, and BP profoundly in a particular pattern.
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  • Experimental and numerical analyses of lightweight foamed concrete as filler for widening embankment

    Shi, Xiaona   Huang, Junjie   Su, Qian  

    In order to control the differential settlement between the existing and widened embankments, lightweight foamed concrete (LWFC) was proposed as a filler of the widened embankment to decrease its self-weight. A series of compressive strength tests, dynamic triaxial tests, dry-wet cycle tests, and water immersion tests were performed to analyze the variation of the LWFC strength with design dry density and the influence of water and adding glass fiber (GF) on the properties of the LWFC. Then two centrifugal models of the widened embankment, which was filled with the LWFC and traditional soil respectively, and their numerical models were established in this study. The results show that water adversely affects the LWFC strength. A lower density for LWFC is corresponded by greater compressive strength loss after the LWFC underwent 15 dry-wet cycles. When the LWFC with a design dry density of 300-800 kg/m(3) was immersed in dead water, the compressive strength and dynamic stress threshold ratios of the LWFC decrease quickly at first and then increases slightly with increasing soaking days. While the LWFC was immersed in live water, these parameters gradually stabilize for a design dry density of no less than 600 kg/m3 and decrease for a design dry density of less than 500 kg/m(3) with increasing soaking days. Mixing GF into the LWFC can significantly improve the compressive strength and dynamic stress threshold and reduce the influence of water. Furthermore, the use of the LWFC as a filler of the widened embankment can significantly decrease the settlement of the embankment surface, soil pressure on the foundation surface, and horizontal deformation of the foundation compared to the traditional soil used as filler for widening embankment. (C) 2020 Elsevier Ltd. All rights reserved.
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  • Urea-derived graphitic carbon nitride as an efficient heterogeneous catalyst for CO2 conversion into cyclic carbonates

    Su, Qian   Sun, Jian   Wang, Jinquan   Yang, Zifeng   Cheng, Weiguo   Zhang, Suojiang  

    In order to overcome existing solid catalysts' disadvantages of low stability and activity, urea-derived graphitic carbon nitrides (u-g-C3N4) with higher stabilities and more active centers were prepared under different temperatures (550-450 degrees C). With a decrease in preparation temperature from 550 degrees C to 480 degrees C, a u-g-C3N4 of lower crystallinity with a smaller polymerization degree was obtained and found to have a higher catalytic activity for CO2 conversion into propylene carbonate. The higher activity of the u-g-C3N4 caused by decreasing the temperature might be ascribed to the lower crystallinity and polymerization degree, which led to more edge defects, wherein the incompletely-coordinated nitrogen atoms served as the main active sites in the cycloaddition reaction. Among all the prepared catalysts, that prepared at 480 degrees C (u-g-C3N4-480) showed the highest catalytic activity for CO2 conversion and exhibited great suitability for other epoxide substrates.
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  • Models for Strength Prediction of High-Porosity Cast-In-Situ Foamed Concrete

    Zhao, Wenhui   Huang, Junjie   Su, Qian   Liu, Ting  

    A study was undertaken to develop a prediction model of compressive strength for three types of high-porosity cast-in-situ foamed concrete (cement mix, cement-fly ash mix, and cement-sand mix) with dry densities of less than 700 kg/m(3). The model is an extension of Balshin's model and takes into account the hydration ratio of the raw materials, in which the water/cement ratio was a constant for the entire construction period for a certain casting density. The results show that the measured porosity is slightly lower than the theoretical porosity due to few inaccessible pores. The compressive strength increases exponentially with the increase in the ratio of the dry density to the solid density and increases with the curing time following the composite function A(2) (In t)(B2) for all three types of foamed concrete. Based on the results that the compressive strength changes with the porosity and the curing time, a prediction model taking into account the mix constitution, curing time, and porosity is developed. A simple prediction model is put forward when no experimental data are available.
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  • Impact of COMT haplotypes on functional connectivity density and its association with the gene expression of dopamine receptors

    Tang, Jie   Li, Yanjun   Xu, Jiayuan   Qin, Wen   Su, Qian   Xu, Qiang   Liu, Bing   Jiang, Tianzi   Yu, Chunshui  

    Catechol-O-methyltransferase (COMT) affects brain connectivity via modulating the dopamine system, with an expected greater effect of haplotypes than single-nucleotide polymorphism (SNP). The action pathway from COMT to dopamine to connectivity is theoretically dependent on the gene expression of dopamine receptors. Here, we aimed to investigate the impact of COMT haplotypes on brain functional connectivity density (FCD) in hundreds of healthy young subjects, and to disclose the association between the COMT-FCD statistical map and the spatial expression of the dopamine receptor genes. We found an inverted U-shaped modulation of COMT haplotypes on FCD in the left inferior parietal lobule that is mainly connected to the frontal and parietal cortices, with APS homozygotes exhibiting greater FCD than the other five groups. However, we failed to identify any significant effect of any SNP on FCD. Utilizing gene expression data collected from Allen human brain atlas, we found the COMT-FCD statistical map was significantly associated with the expression patterns of the dopamine receptor genes. Our results suggest that COMT haplotypes have greater impact on functional connectivity than a single genetic variation and that the association between COMT and functional connectivity may be dependent on the gene expression of dopamine receptors.
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  • Habitual yoghurt consumption and depressive symptoms in a general population study of 19,596 adults.

    Yu, Bin   Zhu, Qi   Meng, Ge   Gu, Yeqing   Zhang, Qing   Liu, Li   Wu, Hongmei   Xia, Yang   Bao, Xue   Shi, Hongbin   Su, Qian   Fang, Liyun   Yu, Fei   Yang, Huijun   Sun, Shaomei   Wang, Xing   Zhou, Ming   Jia, Qiyu   Guo, Qi   Song, Kun   Steptoe, Andrew   Niu, Kaijun  

    PURPOSE: Epidemiological studies directly examining the association between habitual yoghurt consumption and mental health remain scarce. The aim of this study is to investigate the association of yoghurt consumption with depressive symptoms in adults.; METHODS: This is a cross-sectional study of 19,596 Chinese adults (mean age 41.2, standard deviation 11.8years; males, 54.3%). Depressive symptoms were assessed using the Self-Rating Depression Scale (SDS). Dietary intake was obtained through a valid food frequency questionnaire. Multiple logistic regression analysis was conducted to assess the association between yoghurt consumption and depressive symptoms. A number of potential confounders were adjusted in the model.; RESULTS: The prevalence of elevated depressive symptoms was 17.1% (SDS=E2=89=A545). The multivariable adjusted odds ratios (95% CI) of having elevated depressive symptoms by increasing levels of yoghurt consumption (1-3 times/week, 4-7 times/week, and =E2=89=A5twice/day) were 1.05 (0.96, 1.15), 1.02 (0.91, 1.15), and 2.10 (1.61, 2.73) in comparison with lowest consumption group (
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  • Numerical Analysis of Vibration Responses in High-Speed Railways considering Mud Pumping Defect

    Li, Ting   Su, Qian   Shao, Kang   Liu, Jie  

    As a newly appeared defect under slab tracks in high-speed railways, mud pumping weakens the support ability of the subgrade to slab track, bringing about deviations on the vibration responses of the vehicle, slab track, and subgrade. Therefore, this paper proposes a vehicle-slab track-subgrade coupled model based on the multibody simulation principle and the finite element theory to highlight the influences of mud pumping defect. As an external excitation to this model, random track irregularity is considered. In order to simulate the mud pumping defect, the contact between the concrete base and subgrade is described as a spring-damper system. This model is validated by field test results and other simulation results, and a very good agreement is found. The vibration responses of the vehicle, slab track, and subgrade under different mud pumping lengths and train speeds are studied firstly. The deviations of vibration responses in high-speed railways induced by mud pumping are then obtained, and the limited mud pumping length is put forward finally to provide a recommendation for maintenance works of high-speed railways in practice.
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  • Ultra-long room-temperature phosphorescent carbon dots:pH sensing and dual-channel detection of tetracyclines

    Lu, Chunsong   Su, Qian   Yang, Xiaoming  

    Currently, the synthesis and applications of room-temperature phosphorescent (RTP) materials are promising, but challenging. Herein, a kind of ultra-long phosphorescent carbon dots (P-CDs) were rapidly prepared through a facile microwave-directed method. In particular, the yellow-green phosphorescence of the P-CDs was observed for up to 9 s, and their fluorescence and phosphorescence were observed at 418 nm and 525 nm, respectively, using the same excitation at 354 nm. Moreover, the RTP intensity of the P-CDs gradually decreased with the increasing pH because of the protonation-dissociated hydrogen bonds and disturbed phosphorescence sources, whereas their fluorescence exhibited general stability over a wide pH range of 2.1-12.68. Significantly, we found that both the fluorescence and the phosphorescence of the P-CDs were quenched by the introduction of tetracyclines (TCs). Specifically, the P-CDs described herein have abundant -COOH and -OH groups on their surfaces, which facilitate the linkage of CDs with TCs, thus resulting in the occurrence of an inner filter effect process (IFE). Moreover, the P-CDs showed potential as an ideal candidate for building up dual-channel assays towards the targets.
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