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Search Results: 1 - 10 of 80897 matches for " Songqin Liu "
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A Novel Hydrogen Peroxide Sensor via the Direct Electrochemistry of Horseradish Peroxidase Immobilized on Colloidal Gold Modified Screen-printed Electrode
Xiaoxing Xu,Songqin Liu,Huangxian Ju
Sensors , 2003, DOI: 10.3390/s30900350
Abstract: The direct electrochemistry of horseradish peroxidase (HRP) immobilized on a colloidal gold modified screen-printed carbon electrode (HRP-Au-SPCE) and its application as a disposable sensor were studied. The immobilized HRP displayed a couple of stable and well-defined redox peaks with a formal potential of –0.338 V (vs. SCE) and a heterogeneous electron transfer rate constant of (0.75±0.04) s-1 in 0.1 M pH 7.0 PBS. It showed a highly thermal stability, fast amperometric response and an electrocatalytic activity to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator. The biosensor exhibited high sensitivity, good reproducibility, and long-term stability for the determination of H2O2 with a linear range from 0.8 μM to 1.0 mM and a detection limit of 0. 4 μM at 3σ. The variation coefficients are 2.7 % and 2.3 % for over 10 successive assays at the H2O2 concentrations of 8.0 and 20 μM, respectively. The K M app for H2O2 sensor was determined to be 1.3 mM.
Applications of Nanomaterials in Electrochemical Enzyme Biosensors
Huihui Li,Songqin Liu,Zhihui Dai,Jianchun Bao,Xiaodi Yang
Sensors , 2009, DOI: 10.3390/s91108547
Abstract: A biosensor is defined as a kind of analytical device incorporating a biological material, a biologically derived material or a biomimic intimately associated with or integrated within a physicochemical transducer or transducing microsystem. Electrochemical biosensors incorporating enzymes with nanomaterials, which combine the recognition and catalytic properties of enzymes with the electronic properties of various nanomaterials, are new materials with synergistic properties originating from the components of the hybrid composites. Therefore, these systems have excellent prospects for interfacing biological recognition events through electronic signal transduction so as to design a new generation of bioelectronic devices with high sensitivity and stability. In this review, we describe approaches that involve nanomaterials in direct electrochemistry of redox proteins, especially our work on biosensor design immobilizing glucose oxidase (GOD), horseradish peroxidase (HRP), cytochrome P450 (CYP2B6), hemoglobin (Hb), glutamate dehydrogenase (GDH) and lactate dehydrogenase (LDH). The topics of the present review are the different functions of nanomaterials based on modification of electrode materials, as well as applications of electrochemical enzyme biosensors.
Tyrosine phosphorylation of the N-Methyl-D-Aspartate receptor 2B subunit in spinal cord contributes to remifentanil-induced postoperative hyperalgesia: the preventive effect of ketamine
Xiaoping Gu, Xiaoli Wu, Yue Liu, Songqin Cui, Zhengliang Ma
Molecular Pain , 2009, DOI: 10.1186/1744-8069-5-76
Abstract: Intraoperative infusion of remifentanil (0.04 mg/kg, subcutaneous) significantly enhanced mechanical allodynia and thermal hyperalgesia induced by the plantar incision during the postoperative period (each lasting between 2 h and 48 h), which was attenuated by pretreatment with ketamine (10 mg/kg, subcutaneous). Correlated with the pain behavior changes, immunocytochemical and western blotting experiments in our study revealed that there was a marked increase in NR2B phosphorylation at Tyr1472 in the superficial dorsal horn after intraoperative infusion of remifentanil, which was attenuated by pretreatment with ketamine.This study provides direct evidence that tyrosine phosphorylation of the NR2B at Tyr1472 in spinal dosal horn contributes to postoperative hyperalgesia induced by remifentanil and supports the potential therapeutic value of ketamine for improving postoperative hyperalgesia induced by remifentanil.Numerous experimental and clinical studies have convincingly demonstrated that brief opioid exposure can enhance pain sensitivity that presents as opioid-induced hyperalgesia (OIH) [1]. OIH seem to develop more rapidly and more frequently with the administration of the potent, short-acting opioids such as remifentanil than with longer-acting opioids [2]. Clinically, a relative large dose of intraoperative remifentanil has been shown to trigger postoperative secondary hyperalgesia and to require higher doses of morphine for adequate analgesia [3]. In a healthy human volunteers study, the authors found that a skin area with pre-existing mechanical hyperalgesia was significantly enlarged after a 60- to 90-min remifentanil intravenous infusion [4]. Despite extensive studies in this domain, the possible mechanisms underlying this phenomenon are still unclear.It is suggested that spinal N-methyl-D-aspartate receptors (NMDARs) dependent central sensitization, a state that dorsal horn excitability is increased and its response to sensory input is facilitated, may be
Internal Calibration F?rster Resonance Energy Transfer Assay: A Real-Time Approach for Determining Protease Kinetics
Ling Jiang,Yan Liu,Yang Song,Amanda N. Saavedra,Songqin Pan,Wensheng Xiang,Jiayu Liao
Sensors , 2013, DOI: 10.3390/s130404553
Abstract: F?rster resonance energy transfer (FRET) technology has been widely used in biological and biomedical research. This powerful tool can elucidate protein interactions in either a dynamic or steady state. We recently developed a series of FRET-based technologies to determine protein interaction dissociation constant and for use in high-throughput screening assays of SUMOylation. SUMO (small ubiquitin-like modifier) is conjugated to substrates through an enzymatic cascade. This important posttranslational protein modification is critical for multiple biological processes. Sentrin/SUMO-specific proteases (SENPs) act as endopeptidases to process the pre-SUMO or as isopeptidases to deconjugate SUMO from its substrate. Here, we describe a novel quantitative FRET-based protease assay for determining the kinetics of SENP1. Our strategy is based on the quantitative analysis and differentiation of fluorescent emission signals at the FRET acceptor emission wavelengths. Those fluorescent emission signals consist of three components: the FRET signal and the fluorescent emissions of donor (CyPet) and acceptor (YPet). Unlike our previous method in which donor and acceptor direct emissions were excluded by standard curves, the three fluorescent emissions were determined quantitatively during the SENP digestion process from onesample. New mathematical algorithms were developed to determine digested substrate concentrations directly from the FRET signal and donor/acceptor direct emissions. The kinetic parameters, kcat, KM, and catalytic efficiency ( kcat/KM) of SENP1 catalytic domain for pre-SUMO1/2/3 were derived. Importantly, the general principles of this new quantitative methodology of FRET-based protease kinetic determinations can be applied to other proteases in a robust and systems biology approach.
AMP makes native snake muscle fructose-1, 6-bisphosphatase to an alkaline enzyme
Fukun Zhao,Songqin Xu,Lilin Du,Genjun Xu
Science China Life Sciences , 2000, DOI: 10.1007/BF02881711
Abstract: A substance in the crude preparation of NADP+ has been found, which activates snake muscle fructose-1,6-bisphosphatase at pH 9.2 and inhibits the enzyme at pH 7.5. After isolation and extensive characterization, the substance has been determined to be AMP. The activation depends on the concentrations of Mg2+ and could be observed only at concentrations above 1 mmol/L. In the presence of AMP, snake muscle fructose-1,6-bisphosphatase resembles an alkaline enzyme. Kinetic studies indicate that AMP and Mg2+ competitively regulate the activity of the enzyme. AMP releases the inhibition of Mg2+ at high concentration at alkaline pH. It has been reported that fructose-1,6-bisphosphatase with a pH optimum in the alkaline region is caused by limited proteolysis. AMP is also able to make fructose-1,6-bisphosphatase to be an alkaline enzyme. This finding indicates that proteolysis may not be the only reason for shift of the optimum pH of fructose-1,6-bisphosphatase to alkaline side and it may imply some significance in physiological regulation.
The Evolution of Political Ecology and Literary Style in the Late Chin Dynasty
金代后期政治生态与文学风格的演变

Shen Songqin,Long Xiaosong,
沈松勤
,龙小松

浙江大学学报(人文社会科学版) , 2009,
Abstract: In the late Chin Dynasty, the literary style changed largely: the flowery in the Ming-ch'ang and Ch'eng-an periods evolved to be the archaic, elegant in the Chen-You period. This has something to do with the political ecology then, which involved the intellectuals' reflection on the politics of the late period of Emperor Chang-tsung, the Mongolia's invasion, the decline of Chin Dynasty, the interference of the powerful ministers in the state affairs, the yearning of Emperor Hsuan-tsung and Emperor Ai-tsung for resurgence and so on .Because of the difference in their scholarship and self-cultivation as well as life experiences, the literati who tried to promote literary innovation were divided into two entirely different groups. One that stressed self-cultivation, and advocated learning from the ancients and initiating neutral beauty; the other that believed in natural gift and advocated expressing one's inner being and pursuing eccentric and archaic style.
AMP makes native snake muscle fructose-1,6-bisphosphatase to an alkaline enzyme
ZHAO Fukun,XU Songqin,DU Lilin,XU Genjun,
赵辅昆
,徐松琴,杜立林,许根俊

中国科学C辑(英文版) , 2000,
Abstract: A substance in the crude preparation of NADP has been found, which activates snake muscle fructose-1,6-bisphosphatase at pH 9.2 and inhibits the enzyme at pH 7.5. After isolation and extensive characterization, the substance has been determined to be AMP. The activation depends on the concentrations of Mg2 and could be observed only at concentrations above 1 mmol/L. In the presence of AMP, snake muscle fructose-1,6-bisphosphatase resembles an alkaline enzyme. Kinetic studies indicate that AMP and Mg2 competitively regulate the activity of the enzyme. AMP releases the inhibition of Mg2 at high concentration at alkaline pH. It has been reported that fructose-1,6-bisphosphatase with a pH optimum in the alkaline region is caused by limited proteolysis. AMP is also able to make fructose-1,6-bisphosphatase to be an alkaline enzyme. This finding indicates that proteolysis may not be the only reason for shift of the optimum pH of fructose-1,6-bisphosphatase to alkaline side and it may imply some significance in physiological regulation.
The Model of Mobile Knowledge Services System in the Management of Complex Cluster Project  [PDF]
Yong Liu, Bingxin Liu
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.31006
Abstract: Cluster projects are projects of large-scale or with huge investment, such as Beijing 2008 Olympic Games and Shanghai 2010 Expo. A lot of on-site management works are involved in the process of cluster project management, especially the treatment of sudden accidents which would produce plenty of knowledge and experience. As cluster project on-site management spots change frequently, knowledge produced by mobile workers in the process of on-site management is hard to be saved into the knowledge repository on time. It may cause a knowledge distortion or even missing. On the other hand, in the process of cluster project management, a lot of knowledge is required by on-site workers to deal with on-site activities. However, due to lack of effective mechanisms for knowledge communion, they often face the risk of making wrong decisions. To solve the problems of knowledge management and acquisition in the process of cluster project on-site management, this paper presents a system model for mobile knowledge service.
The Collusion Deterrence with Prisoner’s Dilemma  [PDF]
Aidong Liu, Jinfang Liu
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.34053
Abstract: I tried to present a new method to prevent collusion through employing two auditors at the same time and inspiring them provide true report by exploiting their prisoner’s dilemma. But I found this method cannot be put into practice because of the high cost. So I analyzed whether sending the second auditor in a probability, a low cost method, can deter the audit collusion. I find sending the second auditor in a probability, enforcing the rigidly lawful punishment and perfecting the reward mechanism can prevent audit collusion. I also find the auditor’s ethical constraint do good to prevent collusion and the charger of state assets management can play the same role as the real owner of the state-owned enterprise in deterring collusion. This finding provides theory support for the government to implement the publicly audit bidding and random double auditing system on state-owned enterprise. The supervision of PCAOB on auditors is also the operation of this theory.
Using Insulation in China’s Buildings: Potential for Significant Energy Savings and Carbon Emission Reductions  [PDF]
Guoliang Liu, Hans Liu
Low Carbon Economy (LCE) , 2011, DOI: 10.4236/lce.2011.24027
Abstract: Most old residential and commercial buildings in China are not insulated or not to new standards. This is true even in regions with very cold winters or regions with very hot summers. The insulation in new buildings is very poor relative to North American standards. However, insulating the exterior walls, attic roofs, and foundation walls to new standards of buildings in China would reduce the need for heating and air conditioning, and thus would save roughly 200 million tons of coal each year. This in turn would lead to a reduction in CO2 emissions of about 510 million tons per year, which is equal to about 8.4% of China’s total carbon emissions in 2006. The use of insulation in buildings will help homeowners save money, help China save energy and help the environment all at the same time. Insulation will provide a continued payback to the homeowner, not only in dollars and cents, but also by providing a more enjoyable and comfortable living environment for many years.
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