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Role of sortase in Streptococcus mutans under the effect of nicotine

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International Journal of Oral Science 2013年第4期5卷 206-211页

作者： Ming-yun li Rui-Jie Huang xue-Dong Zhou Richard L Gregory School of Dentistry Indiana University State Key Laboratory of Oral Diseases West China Hospital of StomatologySichuan University Department of Pathology and Laboratory Medicine School of MedicineIndiana University

Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen 1/11. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/ll-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased （P~〈 0.05） biofilm metabolic activity （2- to 3-fold increase） as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation （2- to 3-fold increase） as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen 1/11 was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.

关键词： dental caries metabolism nicotine sortase A Streptococcus mutans

Electrochemistry of CeCl3 in Molten liCl-KCl Eutectic

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Chemical Research in Chinese Universities 2014年第3期30卷 489-494页

作者： ZHANG Meng HAN Wei ZHANG Milin li yunna ZHU Fengyan xue yun Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Key Laboratory of Superlight Materials and Surface Technology Ministry of Education Harbin Engineering University Harbin 150001 P. R. China

The electrochemical properties of CeCl3, dissolved in liCI-KCI eutectic melt, were investigated by electrochemical techniques, such as cyclic voltammetry and square wave voltammetry on Mo electrode. It was shown that Ce（Ⅲ） is reduced to Ce（0） based on a three-step mechanism. In a temperature range of 833-923 K, the diffusion coefficient of Ce（Ⅲ） is lgDceoH）=-2.49-1704/T determined by means of the Berzins-Delahay equation with two different expressions under reversible and irreversible conditions. The apparent standard potential of a Ce（Ⅲ）/Ce（0） redox system is ECE^3＋0^＊/Ce^0 =3.551＋0.0006132T（K） vs. Cl2/Cl^-. Some thermochemical properties of CeCl3 solutions were also derived from the electrochemical measurements, such as the enthalpy, entropy, Gibbs free energies and the activity coefficients of Ce（Ⅲ）. The Gibbs free energy of a dilute solution of CeCl3 in this system was determined to be △G^0CeCl3/（kJ·mol^-1）=-1027.9＋0.178T（K） And the activity coefficients, γCeCl3 , range between （7.78-9.14）×10^-3. Furthermore, the standard rate constant of kinetic reaction was calculated to be （4.94-9.72）× 10^-3 cmZ/s and the reaction was regarded as a quasi-reversible reaction under the present experimental conditions at 833 K.

关键词： liCl-KCl eutectic melt CeCl3 Standard rate constant Standard apparent potential Activity coefficient

TLR2 and TLR4 signaling pathways are required for recombinant Brucella abortus BCSP31-induced cytokine production, functional upregulation of mouse macrophages, and the Th1 immune response in vivo and in vitro

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Cellular & Molecular Immunology 2014年第5期11卷 477-494页

作者： Jia-yun li Yuan liu Xiao-xue Gao Xiang Gao Hong Cai State Key Laboratory of Protein and Plant Gene Research College of Life Sciences Peking University Beijing China Model Animal Research Center Nanjing University Nanjing China

Brucella abortus is a zoonotic Gram-negative pathogen that causes brucelosis in ruminants and humans. Toll-like receptors （TLRs） recognize Brucella abortus and initiate antigen-presenting cell activities that affect both innate and adaptive immunity. In this study, we focused on recombinant Brucella cell-surface protein 31 （rBCSP31） to determine its effects on mouse macrophages. Our results demonstrated that rBCSP31 induced TNF-α, IL-6 and IL-12p40 production, which depended on the activation of mitogen-activated protein kinases （MAPKs） by stimulating the rapid phosphorylation of p38 and JNK and the activation of transcription factor NF-KB in macrophages. In addition, continuous exposure （〉24 h） of RAW264.7 cells to rBCSP31 significantly enhanced I FN-y-induced expression of MHC-II and the ability to present rBCSP31 peptide to CD4＋ T cells. Furthermore, we found that rBCSP31 could interact with both TLR2 and TLR4. The rBCSP31-induced cytokine production by macrophages from TLR2-/- and TLR4-/- mice was lower than that from C57BL/6 macrophages, and the activation of NF-KB and MAPKs was attenuated in macrophages from TLR2-/- and TLR4-/- mice. In addition, CD4＋ T cells from C57BL/6 mice immunized with rBCSP31 produced higher levels of IFN-y and IL-2 compared with CD4＋ T cells from TLR2-/- and TLR4-/- mice. Macrophages from immunized C57BL/6 mice produced higher levels of IL-12p40 than those from TLR2-/- and TLR4-/- mice. Furthermore, immunization with rBCSP31 provided better protection in C57BL/6 mice than in TLR2-/- and TLR4-/- mice after B. abortus 2308 challenge. These results indicate that rBCSP31 is a TLR2 and TLR4 agonist that induces cytokine production, upregulates macrophage function and induces the Thl immune response.

关键词： BCSP31 Brucella abortus cytokine macrophage Th i immune response TLR

Study of the material removal mechanism of glass-ceramics based on consecutive incremental loading in ductile-regime grinding

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Nanotechnology and Precision Engineering 2020年第2期3卷 88-95页

作者： xue li State Key Laboratory of Precision Measuring Technology&Instruments Tianjin UniversityTianjin 300072China

Glass-ceramics have many excellent properties and are widely used in various fields. During the grinding process,the workpiece surface is typically subject to material removal by grit of incremental heights, which has rarely been the focus of research. As such, it is necessary to study the material removal mechanism of glass-ceramics under consecutive incremental loading, which more closely reflects the actual grinding process. In this paper,to analyze the plastic deformation and residual stress of lithium aluminosilicate(LAS) glass-ceramics, a finite element model is established based on the Drucker–Prager yield criterion for ductile regimes. A nano-scratch test was also conducted and the test results show that both the residual depth and residual stress increase with an increase in the number of increments, and that consecutive incremental loading promotes the plastic deformation of glass-ceramics and increases the residual stress of the material in the ductile-regime process. These findings provide guidance for achieving higher dimensional accuracy in the actual grinding of glass-ceramics parts.

关键词： Grinding Glass-ceramics Scratch tests Material removal mechanism Consecutive incremental loading

2D phosphides heterostructures on titanium microfiltration membrane for enhanced ampere-level current density overall seawater splitting

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Nano Research 2025年第1期18卷 249-259页

作者： Wenjing Dai Xin Wang Yulong Ma Sisi He Ming Chen Zhaohui Yin Shuheng Tian Maolin Wang Shixiang Yu Hang Zhang Yuanzhe Wang Hong Wang Jianxin li Faming Gao Bowen Cheng yun Wang Zhen Yin Ding Ma Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization College of Chemical Engineering and Materials ScienceTianjin University of Science and TechnologyTianjin 300457China State Key Laboratory of Biobased Fiber Manufacturing Technology Tianjin University of Science and TechnologyTianjin 300457China Haian Institute of High-Tech Research Nanjing UniversityHaian 226600China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Separation Membranes and Membrane Processes Separation Membrane Science and Technology International Joint Research CentreTiangong UniversityTianjin 300387China Centre for Catalysis and Clean Energy School of Environment and ScienceGold Coast CampusGriffith UniversitySouthportQueensland 4222Australia

The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource ***,direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction(ClER).To overcome these issues,we designed a novel NiP_(2)@CoP electrocatalyst on a porous titanium microfiltration(Ti MF)*** obtained bifunctional NiP_(2)@CoP catalyst outperforms the Pt/C and IrO_(2),as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm^(-2) for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in alkaline seawater(1 M KOH+0.5 M NaCl),***,only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm^(-2) towards HER and OER in alkaline seawater,*** importantly,no ClER was observed,demonstrating its excellent selectivity to *** selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas *** promising outcomes obtained with NiP_(2)@CoP catalysts on Ti MF support,therefore,pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.

关键词： direct seawater electrolysis porous titanium microfiltration membrane phosphides heterostructures NiP_(2)@CoP electrocatalyst excellent selectivity to oxygen evolution reaction(OER)

Fabrication and magnetic properties of NiFe-ZnO nano-granular films

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Rare Metals 2013年第3期32卷 269-272页

作者： xue-yun Zhou Dong-Sheng Yao Faculty of Science Jiujiang University Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Tianjin University

Excellent soft magnetic and high frequency prop- erties were obtained successfully in the （Ni75Fe25）x（ZnO）1-x granular films fabricated on the glass substrate by RF magnetron oblique sputtering. The microstructure, mag- netic and high frequency properties were investigated systematically. High resolution transmission electron micrographs show that the film consists of fcc Ni75Fe25 particles uniformly embedded in an amorphous insulating matrix ZnO with particle size a few nanometers. The （Ni75Fe25）x（ZnO）1-x films exhibit excellent soft magnetic properties in a widex range from 0.50 to 0.80 with coer- civity not exceeding 5 × 10^-4 T, which is ascribed to the exchange coupling between magnetic particles. Especially for the sample with x = 0.64, coercivities in hard and easy axes are 5.0 ×10^-5 and 3.6 × 10^-4 T, respectively, and the electric resistivity ρ reaches 1,790 μΩ.cm. The dependence of complex permeability u = u′- ju″on frequency f shows that the real part u′ is more than 130 below 500 MHz, and the ferromagnetic resonance fre- quency fr reaches 1.32 GHz, implying the promising for high frequency application.

关键词： Soft magnetic property Nano-granular thinfilms High frequency application

Fine Root Patterning and Balanced Inorganic Phosphorus Distribution in the Soil Indicate Distinctive Adaptation of Maize Plants to Phosphorus Deficiency

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Pedosphere 2012年第6期22卷 870-877页

作者： ZHANG Yu YU Peng PENG yun-Feng li xue-Xiun CHEN Fan-Jun li Chun-Jian Key Laboratory of Plant-Soil Interactions Ministry of EducationDepartment of Plant NutritionChina Agricultural UniversityBeijing 100193(China)

Plants have diverse strategies to cope with phosphorus （P） deficiency. To better understand how maize responds to P deficiency, a field experiment with two P levels, 0 and 100 kg P205 ha-1 （P0 and P100, respectively）, was carried out as a part of a long-term Pfertilizer field trial. Plant and soil analyses showed that P-deficient maize reduced its growth rate, increased P use efficiency, and formed more thin roots with the diameter less than 0.6 mm at jointing and silking stages, compared to the plants treated with P100. Further, there were no differences in major inorganic P fractions （Ca2-P, Cas-P, Al-P, Fe-P, occluded P and Ca10-P） between the rhizospheric and bulk soils at each harvest, even when soil Olsen-P was only 1.38 mg kg-1. These results suggested that maize responded to P deficiency by reducing the internal P demand for growth and increasing P acquisition ability by favorable root morphological alteration at low carbon cost.

关键词： inorganic phosphorus fractions phosphorus starvation rhizosphere root length root morphology

Long-Term Effects of Inorganic and Organic Amendments on Organic Carbon in a Paddy Soil of the Taihu Lake Region,China

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Pedosphere 2011年第2期21卷 186-196页

作者： MA li YANG lin-Zhang XIA li-Zhong SHEN Ming-Xing YIN Shi-xue li yun-Dong Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 (China) Institute of Agricultural Sciences in Taihu Lake Region Jiangsu Academy of Agricultural Science Suzhou 215155 (China) College of Environmental Science and Engineering Yangzhou University Yangzhou 225009 (China)

A long-term experiment set up in 1980 compared the effects of applying manures and chemical fertilizers on a paddy soil in the Taihu Lake region, China. Of the fourteen randomly distributed treatments consisting of different combinations of organic manure, inorganic nitrogen （N）, phosphorus （P）, and potassium （K）, and rice straw, eight were selected for the present study in 2007. Application of organic manure plus straw significantly increased soil organic carbon （SOC） content of the topsoil （0-10 cm） compared to that of chemical fertilizers alone. The content of SOC was relatively stable in the 10-30 cm layer in the chemical fertilizer treatments and in the 20-40 cm layer in the manure treatments. The stable carbon isotope ratio （513C） ranged from -24% to -28% and increased gradually with depth. The content of SOC was significantly （P 〈 0.05） negatively correlated with 513C. In the 0-20 cm layer, the 513C value significantly decreased in the treatments of manure alone （M）, manure and chemical N and P fertilizers （MNP）, manure and chemical N, P, and K fertilizers （MNPK）, manure, rice straw, and chemical N fertilizer （MRN）, and chemical N fertilizer and rice straw （CNR）, as compared with the no-fertilizer control. In the 30-50 cm layer, however, the ratio significantly increased in all the treatments except Treatment CNR. Mineralization of organic C peaked in the first 2-4 d of incubation and gradually leveled off thereafter over the first 3 weeks, being faster in the manure treatments than the chemical fertilizer treatments. The average rate of mineralization varied from 55.36 to 75.46 mL CO2 kg-1 d-1 and that of stable mineralization from 10 to 20 mL CO2 kg-1 d-1. In eight weeks of incubation, cumulative mineralization was always higher in the manure treatments than the chemical fertilizer treatments, being the highest in Treatment MRN. Combined humus in the soil was mainly （over 50%） composed of tightly combined fraction. The loosely combined humus and its ratio o

关键词： chemical fertilizer humus mineralization organic manure stable carbon isotope ratio

Distributed H∞ filtering of nonlinear systems with random topology by an event-triggered protocol

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Science China(Information Sciences) 2021年第10期64卷 206-220页

作者： yun CHEN Mengze ZHU Renquan LU Anke xue Key Lab for IoT and Information Fusion Technology of Zhejiang Hangzhou Dianzi University School of Automation Guangdong University of Technology

Applying an event-triggered protocol, this paper proposes a distributed Hfilter design for nonlinear perturbed systems under fading measurements with random topology. Nonlinearities in this system obey the one-sided lipschitz constraint, which embraces the conventional lipschitz condition as a special *** sensor network allows random variations of the interconnection strengths between adjacent nodes, and the connection coefficient is determined as the product of a constant and a stochastic variable with a known probabilistic feature. To reduce the unnecessary data transmission and efficiently use the limited bandwidth,the transmissions are orchestrated by an event-triggered regulating strategy. A stochastic bounded real lemma is established for the resulting error dynamics. Based on the presented matrix decomposition, which removes the direct coupling between the statistical information of interconnection strengths and the filter gain, the distributed Hfilter gain can be explicitly expressed and easily solved. The usefulness of the theoretical method is demonstrated in a simulation study.

关键词： sensor network distributed $H_\infty$ filtering one-sided lipschitz condition event-triggered protocol random topology