Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
home > search

Now showing items 49 - 64 of 148

  • Prediction of tire-pavement noise of porous asphalt mixture based on mixture surface texture level and distributions

    Chen, De   Ling, Cheng   Wang, Tingting   Su, Qian   Ye, Anjun  

    An accurate tire-pavement noise prediction model is highly needed by transportation agencies and pavement designers during the porous asphalt mixture design to reduce the tire-pavement noise which has been recognized as a dominant contributor to the overall traffic noise. In this paper, the surface texture level and distributions of porous asphalt mixture are acquired by a recently developed program named as 2-Dimensional Image Texture Analysis Method (2D-ITAM). The acoustic absorption coefficient of porous asphalt mixture is calculated using a proposed sound absorption model based on the micro-structure of porous asphalt mixture. Also, a prediction model correlating the tire-pavement noise level with macro texture and short wavelength of mega-texture of pavement is established using a multivariate non-linear regression analysis. This prediction model is validated through laboratory experiment demonstrating its effectiveness of predicting the tire-pavement noise level. The model is anticipated to serve as an improved tool which could be considered by practitioners in an optimized porous asphalt mixture design incorporating the evaluation of noise produced by asphalt pavement. (C) 2018 Elsevier Ltd. All rights reserved.
    Download Collect
  • Ionic liquids tailored and confined by one-step assembly with mesoporous silica for boosting the catalytic conversion of CO2 into cyclic carbonates

    Su, Qian   Qi, Yaqiong   Yao, Xiaoqian   Cheng, Weiguo   Dong, Li   Chen, Songsong   Zhang, Suojiang  

    On the basis of economic and energy-saving criteria, the minimum effective dose of ionic liquids (ILs) for the catalytic conversion of CO2 into cyclic carbonates was first explored by confinement. With one-step assembly of mesoporous silica (mSiO(2)) by using a fixed amount of silicon source with varying amounts of ILs as templates, certain amounts of 1-ethyl-3-methyl imidazolium bromides (EmimBr) were tailored and confined in mSiO(2). The confined ILs (EmimBr@mSiO(2)) retained the advantages of homo- and heterogeneous catalysts, exhibiting higher performance than bulk EmimBr under identical reaction conditions. Amongst all the prepared materials, EmimBr@mSiO(2) with the lowest amount of EmimBr (6.9 wt%) exhibited the biggest improvement in catalytic activity, achieving a TOF of 112.6 h(-1) which is almost 1.7 times the bulk phase with good recyclability. The boosted catalytic activity could be attributed to the larger proportion of mesopores, the better dispersity of EmimBr (Si/Br =3D 25) and the synergistic effect from more exposed silanol groups (Si-OH/Br =3D 8) in the structure. The good recyclability was then explained by the XPS analysis and density functional theory (DFT) calculation, which confirmed that the compressing effect from Si-OH could enhance the cation and anion interaction to stabilize ILs in the space more firmly when less ILs were confined.
    Download Collect
  • Micro-Embossing Formability of a Superlight Dual-Phase Mg-Li Alloy Processed by High-Pressure Torsion

    Xu, Jie   Su, Qian   Wang, Chenxi   Wang, Xinwei   Shan, Debin   Guo, Bin   Langdon, Terence G.  

    Micro-embossing tests are performed on a coarse-grained (CG) and an ultrafine-grained (UFG) dual-phase Mg-Li alloy processed by high-pressure torsion (HPT) using different widths of the female die at ambient temperature under a force of 9 kN. The surface topography, rib profiles, and microstructures of the cross-sections are measured by scanning electron microscopy, confocal scanning laser microscopy, and optical microscopy, respectively. The interactive effects of the cavity widths of the female die and dual phases on the formability of micro-embossing are analyzed. Numerical simulations are performed to study the effects of the dual-phases on the filling behavior of the CG and UFG alloys. The results show that a UFG Mg-Li alloy reduces the adverse effects of dual phases on the formability of micro-embossing. Micro-channel arrays with channel widths ranging from 50 to 200 mu m are fabricated with good geometrical accuracy using a UFG dual-phase alloy at ambient temperature, thereby establishing the excellent potential for using UFG dual-phase Mg-Li alloys processed by HPT for applications in micro-forming.
    Download Collect
  • Combined effect of pegylated interferon alpha with adefovir on renal function in Chinese patients with chronic hepatitis B.

    Su, Qian   Liu, Yanyan   Li, Jiabin  

    BACKGROUND: Long-term safety of treatment with hepatitis B virus (HBV) polymerase inhibitors is a concern. Adefovir dipivoxil (ADV) and/or interferon alfa (IFN-alpha) therapies have previously been associated with impairment of renal function. Limited data are available on the safety of combination therapy with nucleos (t)ide analogues (NAs) and IFN-alpha. The aim of this analysis was to assess the renal function during combined therapy with pegylated interferon alpha-2b (PEG-IFN-alpha-2b) and ADV versus PEG-IFN-alpha-2b alone in patients with chronic hepatitis B (CHB).; METHODS: We performed a multicenter, prospective, open-label, randomized-controlled trial of renal function data to investigate the efficacy of 48 weeks of therapy with PEG-IFN-alpha-2b and ADV versus PEG-IFN-alpha-2b alone in 102 patients with CHB in Anhui, China. Glomerular filtration rates (GFRs) were calculated by Cockcroft-Gault (CG), abbreviated Modification of Diet in Renal Disease (MDRD) study, and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, and were tested by repeated-measures 1-way analysis of variance within groups. A linear mixed effects model for repeated measures was also used to evaluate the association between baseline information and estimated glomerular filtration rate (eGFR) changes overtime in all enrolled patients. The model considered the baseline age, sex, HBV DNA, aminotransferase, treatment group, time, and group-by-time interaction as fixed effects and incorporated random effects for individual subjects.; RESULTS: After 48 weeks of therapy and further 24 weeks of follow-up, the eGFR decreased both in patients given PEG-IFN-alpha-2b single therapy and combined therapy. Age, HBV DNA, and combined therapy were significant negative predictive factors for eGFR changes.; CONCLUSION: The incidence of renal adverse events in both groups was low, and the combination therapy may have delayed, but reversible renal impairment.=20
    Download Collect
  • Effects of suffosion-induced contact variation on dynamic responses of saturated roadbed considering hydro-mechanical coupling under high-speed train loading

    Liu, Kaiwen   Su, Qian   Yue, Fei   Liu, Bao   Qiu, Ruizhe   Liu, Ting  

    Recent experience of high-speed railway in operation has indicated that the hydro-mechanical coupling effect under dynamic loads from high-speed train may lead to excessive pumping of fine particles in saturated roadbed surface layer. This can result in large variations of contact condition between track and subgrade structure layers while study on this issue remains scare. Based on the theory of fluid dynamics in porous medium and the vehicle-track-subgrade coupling vibration theory, a numerical model is established to evaluate the dynamic responses of saturated roadbed surface resulting from the contact condition variation under the high-speed train load considering the hydro-mechanical coupling effects. A concept of three contact types (fully continuous contact, vibration contact and contact loss) is proposed and three contact shape forms (rectangular, cosine and elliptical shapes) simplified for describing contact damaged zones are compared in terms of dynamic responses (stress, pore water pressure, seepage velocity) evaluated. Also, time-frequency analysis is performed to investigate the influence of contact variation on dynamic responses of roadbed surface in aforementioned contact types. Results show that this progressive development of contact damage can pose extra great stress and pore-water pressures in roadbed and a critical length of contact loss zone is suggested.
    Download Collect
  • Prediction of asphalt mixture surface texture level and its distributions using mixture design parameters (vol 20,pg 557,2017)

    Chen, De   Han, Sen   Ling, Cheng   Su, Qian  

    Download Collect
  • The overall computer/mobile devices usage time is related to newly diagnosed non-alcoholic fatty liver disease:a population-based study

    Meng, Ge   Liu, Fangfang   Fang, Liyun   Li, Chunlei   Zhang, Qing   Liu, Li   Wu, Hongmei   Du, Huanmin   Shi, Hongbin   Xia, Yang   Guo, Xiaoyan   Liu, Xing   Bao, Xue   Su, Qian   Gu, Yeqing   Yu, Fei   Yang, Huijun   Yu, Bin   Sun, Shaomei   Wang, Xing   Zhou, Ming   Jia, Qiyu   Guo, Qi   Chen, Xin   Song, Kun   Wang, Guolin   Huang, Guowei  

    Background: The computer/mobile devices usage time (CMD-UT) is closely related to a sedentary lifestyle, which is an important risk factor for non-alcoholic fatty liver disease (NAFLD). But their direct relationship remains unclear.Aims: We aimed to examine the relationship between CMD-UT and newly diagnosed non-alcoholic fatty liver disease (NAFLD) in Chinese adults.Methods: This cross-sectional study was conducted on 7516 adults in Tianjin, China. The CMD-UT was collected via a questionnaire included five categories. NAFLD [with normal or elevated alanine transaminase (ALT) levels] was diagnosed by at least twice liver ultrasonography examinations and serum ALT concentrations (>41U/L in males and>33U/L in females).Results: The prevalence of overall NAFLD, NAFLD with normal or elevated ALT levels was 18.2, 14.2, and 4.0%, respectively. After adjustments for potential confounding factors, the odds ratios (95% confidence interval) of having overall NAFLD by increasing CMD-UT levels were 1.00 for<1h/d, 1.58 (1.22-2.05) for 1-3h/d, 1.58 (1.18-2.11) for 3-5h/d, 1.65 (1.21-2.27) for 5-10h/d, and 1.99 (1.29-3.05) for 10h/d (P-trend for CMD-UT levels =3D 0.02), respectively. Similar relations were observed with the use of NAFLD with normal or elevated ALT levels.Conclusions: The present study is the first to find that CMD-UT levels are independently associated with NAFLD.Key MessagesThe computer/mobile devices usage time levels are independently associated with the prevalence of non-alcoholic fatty liver disease.
    Download Collect
  • Involvement of prolactin in newborn infant irritability following maternal perinatal anxiety symptoms.

    Zhang, Huiping   Shao, Shuya   Su, Qian   Yao, Dan   Sun, Hongli   Ding, Ding   Dang, Shaokang   Wang, Shan   Zhu, Zhongliang   Li, Hui  

    BACKGROUND: Newborn irritability could be an unique and special status and/or adverse neurobehavioral outcomes which was independent of serious disease. To determine whether maternal perinatal anxiety symptoms was associated with newborn irritability, and whether the alteration of serum prolactin in newborns were involved in newborn irritability.; METHODS: 205 pregnant women were recruited: normal group (n=E2=80=AF=3D=E2=80=AF100), and anxiety group (n=E2=80=AF=3D=E2=80=AF105), which was randomly divided to Newborn Behavioral Observations (NBO)+anxiety group(n=E2=80=AF=3D=E2=80=AF65) and control+anxiety group(n=E2=80=AF=3D=E2=80=AF40). Newborn Irritability was assessed by Neonatal Behavioral Assessment Scale(NBAS). Serum prolactin, cortisol and 5-HT in mothers and infants were measured.; RESULTS: 1. The scores of irritability items in the newborns of anxiety group were higher than that of the normal group (p=E2=80=AF<=E2=80=AF0.05). 2. Lower serum PRL, 5-HT and higher serum cortisol were found in the newborns of anxiety group compared with that of the control group both postpartum 2d and 15 (p=E2=80=AF<=E2=80=AF0.05). 3. The level of serum PRL in newborn infants were significantly and negatively correlated to the scores of irritability items (p=E2=80=AF<=E2=80=AF0.05). 4. After 7 rounds of NBO interventions, the anxiety scores of mothers and the scores of irritability items of newborns in the NBO intervention group were all lower than those of the control group (p=E2=80=AF<=E2=80=AF0.05) .; LIMITATIONS: In future experiments, we should explore the effect of PRL in the breast milk on newborn infant serum PRL.; CONCLUSIONS: Prolactin could be a potential mediator in newborn irritability following maternal perinatal anxiety symptoms. Copyright =C2=A9 2018. Published by Elsevier B.V.
    Download Collect
  • Transcriptome Analysis of FEN1 Knockdown HEK293T Cell Strain Reveals Alteration in Nucleic Acid Metabolism,Virus Infection,Cell Morphogenesis and Cancer Development

    Liu, Song-Bai   Qiu, Xiu-Qin   Guo, Wei-Qiang   Li, Jin-Li   Su, Qian   Du, Jia-Hui   Hu, He-Juan   Wang, Xiao-Xiao   Song, Yao-Hua   Lou, Xiao   Xu, Xiang-Bin  

    Aim and Objective: Flap endonuclease-1 (FEN1 ) plays a central role in DNA replication and DNA damage repair process. In mammals, FEN1 functional sites variation is related to cancer and chronic inflammation, and supports the role of FEN1 as a tumor suppressor. However, FEN1 is overexpressed in multiple types of cancer cells and is associated with drug resistance, supporting its role as an oncogene. knee, it is vital to explore the multi-functions of FEN1 in normal cell metabolic process. This study was undertaken to examine how the gene expression profile changes when FEN1 is downregulated in 293T cells. Materials and Methods: Using the RNA sequencing and real-time PCR approaches, the transcript expression profile of FEN1 knockdown HEK293T cells have been detected for the next step evaluation, analyzation, and validation. Results: Our results confirmed that FEN1 is important for cell viability. We showed that when FEN1 downregulation led to the interruption of nucleic acids related metabolisms, cell cycle related metabolisms are significantly interrupted. FEN1 may also participate in non-coding RNA processing, ribosome RNA processing, transfer RNA processing, ribosome biogenesis, virus infection and cell morphogenesis. Conclusion: These findings provide insight into how FEN1 nuclease might regulate a wide variety of biological processes, and laid the foundation for understanding the role of other RAD2 family nucleases in cell growth and metabolism.
    Download Collect
  • Measurement of Oil-Water Two-Phase Flow Phase Fraction With Ultrasound Attenuation

    Su, Qian   Tan, Chao   Dong, Feng  

    Phase fraction of oil-water two-phase flow is important to the process control and optimization. In this paper, a prediction model based on the mechanism of ultrasound attenuations in oil-water mixture is presented to estimate the phase fraction. This model consists of physical parameters of the two-phase flow and ultrasound frequency, by incorporating the scattering and attenuation of ultrasound in different flow patterns of the oil-water two-phase flow. The nonlinear relationship between ultrasound attenuation coefficient and phase fraction is corrected. An array of 16 ultrasonic transducers with 1-MHz center frequency and 20-Vpp sine acoustic signal is presented to implement this method, and a measuring system was designed and tested on a multiphase flow loop with actual flow experiments. The proposed prediction model showed a good agreement with the online phase fraction calibration in the flow experiments. The average error is 2.3% in water continuous flow, while in 2.8% in oil continuous flow. These findings and the mechanism prediction model provide basic foundations for the phase fraction estimation of oil-water two-phase flow by using the ultrasound attenuation technique.
    Download Collect
  • Corrosion behavior of T2 copper in 3.5% sodium chloride solution treated by rotating electromagnetic field

    Zhang, Peng   Zhu, Qiang   Su, Qian   Guo, Bin   Cheng, Shu-kang  

    Copper is susceptible to producing corrosion problems in corrosive environments, which leads to serious safety problems. Thus, investigating the corrosion behavior of copper is of great significance. The effects of rotating electromagnetic field on corrosion behavior of T2 copper in 3.5% sodium chloride solution with electrochemical measurements were investigated. The results showed that rotating electromagnetic field changed properties of 3.5% sodium chloride solution by increasing the values of temperature and pH and decreasing the values of conductivity and dissolved oxygen. The rotating electromagnetic field improved the corrosion resistance of T2 copper. The corrosion products of T2 copper in treated 3.5% sodium chloride solution were composed of Cu2O and CuCl. The low corrosion rate of T2 copper was resulted from the decrease of dissolved oxygen in 3.5% sodium chloride solution treated by rotating electromagnetic field.
    Download Collect
  • Study on the Heat of Hydration and Strength Development of Cast-In-Situ Foamed Concrete

    Zhao, Wenhui   Su, Qian   Han, Feng   Wang, Wubin  

    This study aims to investigate the relationship between the heat of hydration and the strength development of cast-in-situ foamed concrete. First, indoor model tests are conducted to determine the effects of the casting density and the fly ash content on the hydration heat of foamed concrete in semiadiabatic conditions. Second, compression tests are carried out to evaluate the development of the compressive strength with the curing time under standard curing conditions and temperature matched curing conditions. Third, the hydration heat development of the foamed concrete is tested in four projects. The results showed that the peak temperature, the maximum temperature change rate, and the maximum temperature difference increased with the increase in the casting density at different positions in the foamed concrete. For the same casting density of the foamed concrete, the peak temperature, the maximum temperature change rate, and the maximum temperature difference decreased with the increase in the fly ash content. For the foamed concrete without the admixture, the early strength was significantly higher under temperature matched curing conditions than under standard curing conditions, but the temperature matched curing conditions had a clear inhibitory effect on the strength of the foamed concrete. The strengths during the early stage and the later stage were both improved under temperature matched curing conditions after adding the fly ash, and the greater the fly ash content, the larger the effect. The maximum temperature increments were higher in the indoor model test than in the field tests for the same casting density. Reasonable cooling measures and the addition of fly ash decreased the maximum temperature increments and increased the corresponding casting times.
    Download Collect
  • iOS Data Recovery Using Low-Level NAND Images

    Qiu, Wei-dong   Su, Qian   Liu, Bo-zhong   Li, Yan  

    To recover erased data from iOS devices, specialists first decrypt passwords, then extract data images directly from low-level NAND storage and analyze the redundancy caused by its file translation layer (FTL) behavior.
    Download Collect
  • Expression of neurogranin in hippocampus of rat offspring exposed to restraint stress and pulsed magnetic fields.

    Li, Qinghong   Cheng, Daxin   Chen, Rui   Cai, Qing   Jia, Ning   Su, Qian   Zhang, Huiping   Zhu, Zhongliang   Zeng, Junan   Li, Hui  

    Stressor acting upon the organism during pregnancy can produce distinct and long lasting effects on the offspring. However, the essential mechanism remains unclear. Neurogranin (Ng) is a postsynaptic brain-specific protein involved in the regulation of calcium signaling and neuronal plasticity. Our purpose was to investigate whether Ng plays a regulating role in the effects of prenatal restraint stress (PS) and prenatal pulsed magnetic fields (PMFs) on the hippocampus of rat offspring. Sprague Dawley female rats at gestational days 14-20 were given restraint stress or pulsed magnetic fields. The male and female offspring rats were sacrificed at the age of 1 month. The expression of Ng in the offspring hippocampus was determined using immunohistochemistry and western blotting. The results showed that PS induces a significantly inhibitory effect on the expression of Ng, especially in female offspring. The 0.11 T of prenatal PMFs could increase the expression of Ng in offspring hippocampus. There was no significant difference between female and male offspring in PMFs group. The prenatal restraint stress-induced decrease in Ng expression in offspring hippocampus might be associated with the deficit in spatial learning and memory reported previously. The 0.11 T of prenatal PMFs induced a significant stimulatory effect on protein expression of Ng. It was believed that PMFs stress might enhance the synaptic growth and remodeling. Copyright =C2=A9 2014 Elsevier B.V. All rights reserved.
    Download Collect
  • Field investigation and full-scale model testing of mud pumping and its effect on the dynamic properties of the slab track-subgrade interface

    Huang, Junjie   Su, Qian   Wang, Wei   Pham Duc Phong   Liu, Kaiwen  

    Passenger comfort and safety are the most important aspects in the operation of high-speed railways. Mud pumping is a typical problem that occurs in the slab track and the subgrade interface, which influences passenger comfort and safety. In this paper, various field investigations and a full-scale model of the slab track and the subgrade are presented. The external and internal characteristics of mud pumping in the slab track-subgrade interface and the influence of mud pumping on the dynamic properties of the slab track-subgrade are analyzed. The results show that mud pumping only occurs at the expansion joints in the concrete base of the slab track structure. This happens due to the infiltration of rainwater into the subgrade bed through the cracks in the expansion joints. When the upper layer of the subgrade is kept saturated in the full-scale model, mud pumping is found to occur after 3.0 x 10(4) loading cycles. The vibration ratio of the subgrade surface to the concrete base gradually increases with continued cyclic loading. In addition, the cumulative settlement of the subgrade increased continuously. After 2.0 x 10(6) loading cycles, it was found that a large volume of slurry composed of water and fine particles was squeezed out of the subgrade bed, and mud pumping occurred on the surface of the subgrade bed leading to the formation of a mud layer between the concrete base and the subgrade bed, causing a loss of contact between the subgrade bed and the concrete base. This reduces the ability of the subgrade bed to support the slab track structure.
    Download Collect
  • Transesterification of Isosorbide with Dimethyl Carbonate Catalyzed by Task-Specific Ionic Liquids

    Qian, Wei   Tan, Xin   Su, Qian   Cheng, Weiguo   Xu, Fei   Dong, Li   Zhang, Suojiang  

    Green synthesis of high-molecular-weight isosorbide-based polycarbonate (PIC) with excellent properties is a tremendous challenge and is profoundly influenced by the precursor. Herein, an ecofriendly catalyst was employed to obtain the more reactive PIC precursor dicarboxymethyl isosorbide (DC) with 99.0 % selectivity through the transesterification reaction of isosorbide with dimethyl carbonate. This is the indispensable stage of a one-pot green synthesis of PIC, playing a critical role in giving an insight into the polymerization mechanism of polymer synthesis through the melt transesterification reaction. To this end, a series of 4-substituted phenolate ionic liquids (ILs) were developed as a new type of high-efficiency catalyst for this reaction. These homogeneous ILs exhibited outstanding catalytic performances. The DC selectivity increased gradually with decreasing IL basicity; among the ILs studied, trihexyl(tetradecyl)phosphonium 4-iodophenolate ([P-66614][4-I-Phen]) showed the highest catalytic activity. Additionally, according to the experimental results and DFT calculations, a plausible nucleophilic activation mechanism was proposed, which confirmed that the reaction is activated through the formation of H-bonds and electrostatic interactions with the IL catalyst. This strategy of tunable basicity and structure of anions in ILs affords an opportunity to develop other ILs for the transesterification reaction, thereby conveniently providing a variety of polymers through a green synthetic pathway.
    Download Collect
1 2 3 4 5 6 7 8 9 10

Contact

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

Submit Feedback