The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI...The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI inducer, and therefore the lack of production of small molecules of Acyl homoserine lactone (AHL). Previous studies had shown that it does not harbor the inducer of the regulatory molecule (AHL). Nevertheless, it is able to regulate these same functions (biofilm, violacein) via AHLs. This could mean the presence of specific receptors for these induction molecules, belonging to the LuxR family. The aim of this study was to test these hypotheses using molecular analysis. Genome sequencing of the P. ulvae TC14 strain was carried out by Molecular Research LP (MR DNA), using the Illumina Hiseq 2500 method. The results revealed the presence of 2,293,242 base pairs, i.e. 100% of the genomic volume. The number of coding gene sequences was 1983, and the Guanine + Cytosine (G+C) percentage of the base number was 41.55%, revealing stability in the sequenced genome. In order to verify the identity of the sequenced genome, a phylogenetic analysis based on RNA16S was carried out. This analysis resulted in 93% homology with the previously sequenced and characterized species Pseudoalteromonas tunicata, showing that it belongs to the genus Pseudoalteromonas. To these comparative results should be added those derived from genome analysis based on nucleotide percentage using the tools available at https://img.jgi.doe.gov/. The results showed that Pseudoalteromonas tunicata D2 has the highest percentage nucleotide identity (ANI) (75.7913%), followed by Pseudoalteromonas flavipulchra NCIMB2033 (72.2736%) and Pseudoalteromonas phenolica KCTC 12086 (71.6685%). Next, the search for the various genes involved in QS was carried out using sequence comparisons via the BLAST method. For LuxI, sequence templates from the genomes of Vibrio, Chromobacterium, Shewanella or even other Pseudoalteromonas species were screened against the TC14 genome. This yielded no conclusive results synonymous with the non-presence of LuxI in TC14 as assumed by previous research. The search for LuxR, on the other hand, gave rise to the presence of eight presumptive sequences. Molecular characterization of the presumptive LuxR sequences was carried out to assess their gene expression. This characterization showed expression of these LuxR homologous sequences in a range from o.11 to 5.33 picograms (pg). Even if these sequences were not analyzed in depth, the retro-transcription technique nevertheless showed a minimum of activity, which could enable us to distinguish them from inactive sequences. The next step was to compare the LuxRs found in TC14 with the so-called Solo LuxRs, which act autonomously. This study shows that P. ulvae TC14 is a bacterium with a particular LuxR-based communication system.展开更多
In interdigitated back contact(IBC)solar cells,the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation.The result shows that the variation of the metal coverage ratio(MCR)will affect both th...In interdigitated back contact(IBC)solar cells,the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation.The result shows that the variation of the metal coverage ratio(MCR)will affect both the surface passivation and the electrode-contact properties for the p-type emitter in IBC solar cells.We find that when R_(c) ranges from 0.08 to 0.16Ω·cm^(2),the MCR is optimized with a value of 25%and 33%,resulting in a highest energy-conversion efficiency.The dependences of both Voc and fill factor on MCR are simulated in order to explore the mechanism of the IBC solar cells.展开更多
Based on the Joukowsky transformation and Theodorsen method, a novel parametric function （shape function） for wind turbine airfoils has been developed. The airfoil design space and shape control equations also have ...Based on the Joukowsky transformation and Theodorsen method, a novel parametric function （shape function） for wind turbine airfoils has been developed. The airfoil design space and shape control equations also have been studied. Results of the analysis of a typical wind turbine airfoil are shown to illustrate the evaluation process and to demonstrate the rate of convergence of the geometric characteristics. The coordinates and aerodynamic performance of approximate airfoils is rapidly close to the baseline airfoil corresponding to increasing orders of polynomial. Comparison of the RFOIL prediction and experimental results for the baseline airfoil generally show good agreement. A universal method for three-dimensional blade integration-＂ Shape function/Distribution function＂ is presented. By changing the parameters of shape function and distribution functions, a three dimensional blade can be designed and then transformed into the physical space in which the actual geometry is defined. Application of this method to a wind turbine blade is presented and the differences of power performance between the represented blade and original one are less than 0. 5%. This method is particularly simple and convenient for bodies of streamline forms.展开更多
文摘The communication system known as quorum sensing (QS) in gram-negative bacteria regulates biofilm formation and many other functions. The particularity of Pseudoalteromonas ulvae TC14 seems to be the absence of a LuxI inducer, and therefore the lack of production of small molecules of Acyl homoserine lactone (AHL). Previous studies had shown that it does not harbor the inducer of the regulatory molecule (AHL). Nevertheless, it is able to regulate these same functions (biofilm, violacein) via AHLs. This could mean the presence of specific receptors for these induction molecules, belonging to the LuxR family. The aim of this study was to test these hypotheses using molecular analysis. Genome sequencing of the P. ulvae TC14 strain was carried out by Molecular Research LP (MR DNA), using the Illumina Hiseq 2500 method. The results revealed the presence of 2,293,242 base pairs, i.e. 100% of the genomic volume. The number of coding gene sequences was 1983, and the Guanine + Cytosine (G+C) percentage of the base number was 41.55%, revealing stability in the sequenced genome. In order to verify the identity of the sequenced genome, a phylogenetic analysis based on RNA16S was carried out. This analysis resulted in 93% homology with the previously sequenced and characterized species Pseudoalteromonas tunicata, showing that it belongs to the genus Pseudoalteromonas. To these comparative results should be added those derived from genome analysis based on nucleotide percentage using the tools available at https://img.jgi.doe.gov/. The results showed that Pseudoalteromonas tunicata D2 has the highest percentage nucleotide identity (ANI) (75.7913%), followed by Pseudoalteromonas flavipulchra NCIMB2033 (72.2736%) and Pseudoalteromonas phenolica KCTC 12086 (71.6685%). Next, the search for the various genes involved in QS was carried out using sequence comparisons via the BLAST method. For LuxI, sequence templates from the genomes of Vibrio, Chromobacterium, Shewanella or even other Pseudoalteromonas species were screened against the TC14 genome. This yielded no conclusive results synonymous with the non-presence of LuxI in TC14 as assumed by previous research. The search for LuxR, on the other hand, gave rise to the presence of eight presumptive sequences. Molecular characterization of the presumptive LuxR sequences was carried out to assess their gene expression. This characterization showed expression of these LuxR homologous sequences in a range from o.11 to 5.33 picograms (pg). Even if these sequences were not analyzed in depth, the retro-transcription technique nevertheless showed a minimum of activity, which could enable us to distinguish them from inactive sequences. The next step was to compare the LuxRs found in TC14 with the so-called Solo LuxRs, which act autonomously. This study shows that P. ulvae TC14 is a bacterium with a particular LuxR-based communication system.
文摘In interdigitated back contact(IBC)solar cells,the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation.The result shows that the variation of the metal coverage ratio(MCR)will affect both the surface passivation and the electrode-contact properties for the p-type emitter in IBC solar cells.We find that when R_(c) ranges from 0.08 to 0.16Ω·cm^(2),the MCR is optimized with a value of 25%and 33%,resulting in a highest energy-conversion efficiency.The dependences of both Voc and fill factor on MCR are simulated in order to explore the mechanism of the IBC solar cells.
基金Supported by the National Natural Science Foundation of China （ No. 50775227 ） and the Natural Science Foundation of Chongqing （ No. CSTC, 2008BC3029）.
文摘Based on the Joukowsky transformation and Theodorsen method, a novel parametric function （shape function） for wind turbine airfoils has been developed. The airfoil design space and shape control equations also have been studied. Results of the analysis of a typical wind turbine airfoil are shown to illustrate the evaluation process and to demonstrate the rate of convergence of the geometric characteristics. The coordinates and aerodynamic performance of approximate airfoils is rapidly close to the baseline airfoil corresponding to increasing orders of polynomial. Comparison of the RFOIL prediction and experimental results for the baseline airfoil generally show good agreement. A universal method for three-dimensional blade integration-＂ Shape function/Distribution function＂ is presented. By changing the parameters of shape function and distribution functions, a three dimensional blade can be designed and then transformed into the physical space in which the actual geometry is defined. Application of this method to a wind turbine blade is presented and the differences of power performance between the represented blade and original one are less than 0. 5%. This method is particularly simple and convenient for bodies of streamline forms.
