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Search Results: 1 - 10 of 28553 matches for " Baolin Sun "
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Alternative Sigma Factor σH Modulates Prophage Integration and Excision in Staphylococcus aureus
Liang Tao equal contributor,Xiaoqian Wu equal contributor,Baolin Sun
PLOS Pathogens , 2010, DOI: 10.1371/journal.ppat.1000888
Abstract: The prophage is one of the most important components of variable regions in bacterial genomes. Some prophages carry additional genes that may enhance the toxicity and survival ability of their host bacteria. This phenomenon is predominant in Staphylococcus aureus, a very common human pathogen. Bioinformatics analysis of several staphylococcal prophages revealed a highly conserved 40-bp untranslated region upstream of the int gene. A small transcript encoding phage integrase was identified to be initiated from the region, demonstrating that the untranslated region contained a promoter for int. No typical recognition sequence for either σA or σB was identified in the 40-bp region. Experiments both in vitro and in vivo demonstrated that σH recognized the promoter and directed transcription. Genetic deletion of sigH altered the int expression, and subsequently, the excision proportion of prophage DNAs. Phage assays further showed that sigH affected the ability of spontaneous lysis and lysogenization in S. aureus, suggesting that sigH plays a role in stabilizing the lysogenic state. These findings revealed a novel mechanism of prophage integration specifically regulated by a host-source alternative sigma factor. This mechanism suggests a co-evolution strategy of staphylococcal prophages and their host bacteria.
Performance of Network Coding Based Multipath Routing in Wireless Sensor Networks
Baolin Sun,Chao Gui,Ying Song,Ting Zhang
International Journal of Computer Science Issues , 2012,
Abstract: In recent times, there have been many advances in the field of information theory and wireless sensor network (WSN) technologies. Network coding is a new paradigm in data transport and promises to change many aspects of WSN. In this paper, we introduce an analytical framework to study the performance of network coding based multipath routing, and proposes a Network Coding based Multipath Routing algorithm, in comparison with replication based multipath routing in WSN (NCMR). It is typically proposed in order to increase the reliability of data transmission or to provide load balancing. In our simulation, we compare NCMR routing protocol with AODVM and MDSR routing protocol, in terms of the packet delivery rate, average packet delivery delay, packet loss probability and network lifetime when a packet is transmitted. The simulation results show that the NCMR routing protocol provide an accurate and efficient method of estimating and evaluating the route stability in dynamic WSNs.
Staphylococcus aureus autoinducer-2 quorum sensing decreases biofilm formation in an icaR-dependent manner
Yu Dan,Zhao Liping,Xue Ting,Sun Baolin
BMC Microbiology , 2012, DOI: 10.1186/1471-2180-12-288
Abstract: Background Staphylococcus aureus is an important pathogen that causes biofilm-associated infection in humans. Autoinducer 2 (AI-2), a quorum-sensing (QS) signal for interspecies communication, has a wide range of regulatory functions in both Gram-positive and Gram-negative bacteria, but its exact role in biofilm formation in S. aureus remains unclear. Results Here we demonstrate that mutation of the AI-2 synthase gene luxS in S. aureus RN6390B results in increased biofilm formation compared with the wild-type (WT) strain under static, flowing and anaerobic conditions and in a mouse model. Addition of the chemically synthesized AI-2 precursor in the luxS mutation strain (ΔluxS) restored the WT phenotype. Real-time RT-PCR analysis showed that AI-2 activated the transcription of icaR, a repressor of the ica operon, and subsequently a decreased level of icaA transcription, which was presumably the main reason why luxS mutation influences biofilm formation. Furthermore, we compared the roles of the agr-mediated QS system and the LuxS/AI-2 QS system in the regulation of biofilm formation using the ΔluxS strain, RN6911 and the Δagr ΔluxS strain. Our data indicate a cumulative effect of the two QS systems on the regulation of biofilm formation in S. aureus. Conclusion These findings demonstrate that AI-2 can decrease biofilm formation in S. aureus via an icaR-activation pathway. This study may provide clues for therapy in S. aureus biofilm-associated infection.
Comparative Study of the Shielding Properties of Slotted Enclosure with Inner or Outer Excitations Using FEM  [PDF]
Baolin Nie, Pingan Du
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.32B009
Abstract: Finite element method (FEM) is employed in this paper to conduct the comparative study of the shielding properties of enclosure with outer and inner excitations. Plane wave is adopted for the outer excitation case while coaxial cable is utilized to model the inner excitation source. Moreover, the resonance phenomena of slotted enclosure under different excitation are studied in detail. Finally, some conclusions with regard to the relationships and distinctions between the inner and outer excitations for the same enclosure are proposed.
Adsorption of Cd(II) from acidic aqueous solutions by tourmaline as a novel material
CuiPing Wang,BaoLin Wang,JingTing Liu,Li Yu,HongWen Sun,JiZhou Wu
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5341-6
Abstract: Batch experiments were conducted to investigate the behavior and mechanisms for the adsorption of Cd(II) from aqueous solutions by tourmaline under acidic conditions. The results indicated that the adsorption of Cd(II) significantly depend on the adsorption time, temperature, and the initial concentration of the metal ion. Furthermore, tourmaline had a very good adsorption capacity for Cd(II) in acidic, neutral and alkaline aqueous solutions. This good adsorption capacity is attributed to the observation that tourmaline can automatically adjust the pH values of acidic (except pH 2.0 and 3.0), neutral or alkaline aqueous solutions to 6.4. Specifically, the removal capacity for Cd(II) was higher at strongly acidic pH values (in contrast to industrial wastewater pH values) compared to that obtained for other types of adsorbents. Furthermore, the results obtained in this study showed good fits to the Langmuir and Freundlich adsorption isotherms. However, the Langmuir model fit better than the Freundlich model. The maximum uptake of Cd(II) by tourmaline was 31.77, 33.11 and 40.16 mg/g at pH 4.0 at 15, 25 and 35°C, respectively. Therefore, tourmaline is an effective adsorbent for the removal of Cd(II) from acidic aqueous solutions. In addition, the kinetics for the Cd(II) adsorption by tourmaline closely followed the pseudo-second-order model. The thermodynamic parameters indicated that adsorption was feasible, spontaneous, and endothermic. Furthermore, the pH variation after adsorption, gZ-potential, metal ions desorbed and released, and FT-IR analysis indicated that the physisorption and chemisorption mechanisms of tourmaline for heavy metals. These mechanisms included water that was automatically polarized by tourmaline, the ion exchange process, and electropolar adsorption. Among the mechanisms, the automatic polarization of water caused by tourmaline is a unique adsorption mechanism for tourmaline.
Multiple constraints QoS multicast routing optimization algorithm in MANET based on GA

Baolin Sun,Shangchao Pi,Chao Gui,Yue Zeng,Bing Yan,Wenxiang Wang,Qianqing Qin,

自然科学进展 , 2008,
Abstract: Usually multiple quality of service (QoS) guarantees are required in most multicast applications. This paper presents a multiple constraints algorithm for multicast traffic engineering in mobile ad hoc networks (MANET). The proposed algorithm is a new version of multiple constraints QoS multicast routing optimization algorithm in MANET based on genetic algorithm (MQMGA). The proposed MQMGA can optimize the maximum link utilization, the cost of the multicast tree, the selection of the long-life path, the average delay and the maximum end-to-end delay. Experimental result shows that the approach is efficient, has promising performance in multicast traffic engineering and for evaluating the route stability in dynamic mobile networks.
A Physical Explanation on Solar Microwave Zebra Pattern with the Current-carrying Plasma Loop Model
Baolin Tan
Physics , 2009, DOI: 10.1007/s10509-009-0193-5
Abstract: Microwave zebra pattern structure is an intriguing fine structure on the dynamic spectra of solar type IV radio burst. Up to now, there isn't a perfect physical model for the origin of the solar microwave zebra pattern. Recently, Ledenev, Yan and Fu (2006) put forward an interference mechanism to explain the features of microwave zebra patterns in solar continuum events. This model needs a structure with a multitude of discrete narrow-band sources of small size. Based on the model of current-carrying plasma loop and the theory of tearing mode instability, we proposed that the above structure does exist and may provide the main conditions for the interference mechanism. With this model, we may explain the frequency upper limit, the formation of the parallel and equidistant stripes, the superfine structure and intermediate frequency drift rate of the zebra stripes. If this explanation is valid, the zebra pattern structures can reveal some information of the motion and the inner structures of the coronal plasma loops.
Coronal Heating Driven by A Magnetic-gradient Pumping Mechanism in Solar Plasmas
Baolin Tan
Physics , 2014, DOI: 10.1088/0004-637X/795/2/140
Abstract: The solar coronal heating is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with considerable magnetic gradient from solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism and try to explain the formation of hot plasma upflows, such as the hot type II spicules and hot plasma ejections, etc. In MGP mechanism, the magnetic gradients drive the energetic particles to move upwards from the underlying solar atmosphere and form hot upflows. These upflow energetic particles deposit in corona and make it becoming very hot. Roughly estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km/s in chromosphere and about 130 km/s in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them and deposit in the corona. The deposition of energetic particles will make the corona become hot, and their escaping from the photosphere will make the underlying photosphere a bit cold. This mechanism present a natural explanation to the mystery of solar coronal heating.
A Peculiar Microwave Quasi-periodic Pulsation with Zigzag Pattern in a CME-related Flare on 2005-01-15
Baolin Tan
Physics , 2013, DOI: 10.1017/S1743921313003281
Abstract: A peculiar microwave quasi-periodic pulsation with zigzag pattern (Z-QPP) is observed first by the Chinese Solar Broadband Spectrometer in Huairou (SBRS/Huairou) at 1.10-1.34 GHz in a solar flare on 2005-01-15. The Z-QPP occurred just in the early rising phase of the flare with weakly right-handed circular polarization. Its period is only several decades millisecond. Particularly, before and after the pulsation, there are many spectral fine structures, such as zebra patterns, fibers, and millisecond spikes. The microwave Z-QPP can provide some kinematic information of the source region in the early rising phase of the flare, and the source width changes from about 1000 km to 3300 km, even if we have no imaging observations. The abundant spectral fine structures possibly reflect the dynamic features of non-thermal particles.
Multi-timescale Solar Cycles and the Possible Implications
Baolin Tan
Physics , 2010, DOI: 10.1007/s10509-010-0496-6
Abstract: Based on analysis of the annual averaged relative sunspot number (ASN) during 1700 -- 2009, 3 kinds of solar cycles are confirmed: the well-known 11-yr cycle (Schwabe cycle), 103-yr secular cycle (numbered as G1, G2, G3, and G4, respectively since 1700); and 51.5-yr Cycle. From similarities, an extrapolation of forthcoming solar cycles is made, and found that the solar cycle 24 will be a relative long and weak Schwabe cycle, which may reach to its apex around 2012-2014 in the vale between G3 and G4. Additionally, most Schwabe cycles are asymmetric with rapidly rising-phases and slowly decay-phases. The comparisons between ASN and the annual flare numbers with different GOES classes (C-class, M-class, X-class, and super-flare, here super-flare is defined as $\geq$ X10.0) and the annal averaged radio flux at frequency of 2.84 GHz indicate that solar flares have a tendency: the more powerful of the flare, the later it takes place after the onset of the Schwabe cycle, and most powerful flares take place in the decay phase of Schwabe cycle. Some discussions on the origin of solar cycles are presented.
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