Insights into SusCD-mediated glycan import by a prominent gut symbiont

In Bacteroidetes, one of the dominant phyla of the mammalian gut, active uptake of large nutrients across the outer membrane is mediated by SusCD protein complexes via a “pedal bin” transport mechanism. However, many features of SusCD function in glycan uptake remain unclear, including ligand binding, the role of the SusD lid and the size limit for substrate transport. Here we characterise the β2,6 fructo-oligosaccharide (FOS) importing SusCD from Bacteroides thetaiotaomicron (Bt1762-Bt1763) to shed light on SusCD function. Co-crystal structures reveal residues involved in glycan recognition and suggest that the large binding cavity can accommodate several substrate molecules, each up to ~2.5 kDa in size, a finding supported by native mass spectrometry and isothermal titration calorimetry. Mutational studies in vivo provide functional insights into the key structural features of the SusCD apparatus and cryo-EM of the intact dimeric SusCD complex reveals several distinct states of the transporter, directly visualising the dynamics of the pedal bin transport mechanism

Model-Based Verification, Optimization, Synthesis and Performance Evaluation of Real-Time Systems

International audienceThis article aims at providing a concise and precise Travellers Guide, Phrase Book or Reference Manual to the timed automata modeling formalism introduced by Alur and Dill [8, 9]. The paper gives comprehensive definitions of timed automata, priced (or weighted) timed automata, and timed games and highlights a number of results on associated decision problems related to model checking, equivalence checking, optimal scheduling, the existence of winning strategies, and then statistical model checking

Porphyromonas gingivalis fimbrial protein Mfa5 contains a von Willebrand factor domain and an intramolecular isopeptide

The Gram negative bacterium Porphyromonas gingivalis is a secondary colonizer of the oral biofilm and is involved in the onset and progression of periodontitis. Its fimbriae, of type V, are important for attachment to other microorganisms in the biofilm and for adhesion to host cells. The fimbriae are assembled from five proteins encoded by the mfa1 operon, of which Mfa5 is one of the ancillary tip proteins. Here we report the X ray structure of the N terminal half of Mfa5, which reveals a von Willebrand factor domain and two IgG like domains. One of the IgG like domains is stabilized by an intramolecular isopeptide bond, which is the first such bond observed in a Gram negative bacterium. These features make Mfa5 structurally more related to streptococcal adhesins than to the other P. gingivalis Mfa proteins. The structure reported here indicates that horizontal gene transfer has occurred among the bacteria within the oral biofil

Anion Effect of Zinc Source on Chemically Deposited ZnS(O,OH) Films

The study on the anion effect of different Zn sources—Zn(CH3COO)2, ZnCl2, ZnI2, Zn(NO3)2 and ZnSO4—on the chemical deposition of ZnS(O,OH) films revealed that the growth rate and composition of the ZnS(O,OH) layer depend on the instability constant (pK) value of the corresponding Zn-complex Zn(L)n in the chemical bath solution. In the region of pKZn(NH3)2+>pKZn(L)n the ZnS(O,OH) film's growth rate and ZnS concentration in films increased with the increasing pK value of the used Zn salt complex up to the pK value of the Zn[NH3]2+ complex and decreased in the region where pKZn(NH3)2+<pKZn(L)n. The band gap values (around 3.6 eV in most cases) of deposited ZnS(O,OH) films did not depend on the Zn precursor's instability constant, the ZnS(O,OH) film from zinc nitrate containing bath has higher band gap energy (Eg = 3.8 eV). The maximum efficiency of CISSe and CZTSSe monograin layer solar cells was gained with ZnS(O,OH) buffer layer deposited from CBD solution containing Zn(CH3COO)2 as Zn source, which provided the highest growth rate and ZnS concentration in the ZnS(O,OH) film on glass substrates

Low temperature time resolved photoluminescence in ordered and disordered Cu2ZnSnS4 single crystals

International audienc

Comparison of CdS films deposited from chemical baths containing different doping impurities. Thin Solid Films 2005

Abstract The results obtained for CdS films chemically deposited from solutions containing different impurities known as donor type dopants for CdS (chlorine, iodine, boron and indium) are reported. CdS films were deposited onto glass and CuInSe 2 absorber substrates at 85 8C. The deposition baths were ammonia solutions containing 0.001 M Cd 2+ , 0.02 M ammonium compound and 0.002 M thiourea and CdS was deposited at pH 10.3. After deposition, the layers were heated at 200 8C for 30 min in vacuum. The results confirm that the electrical resistivity of CdS films doped with boron and chlorine was dependent on doping level. At the same time, characteristics of CuInSe 2 solar cells with differently doped CdS did not show any remarkable dependence on doping level and nature. The buried homojunction model is proposed to explain obtained results.

Filtering test models to support incremental testing

Model-based testing can be hampered by the fact that a model depicting the system as designed does not necessarily correspond to the product as it is during development. Tests generated from such a model may be impossible to execute due to unimplemented features and already known errors. This paper presents a solution in which parts of the model can be filtered out and the remainder used to generate tests for the implemented portion of the product. In this way model-based testing can be used to gradually test the implementation as it becomes available. This is particularly important in incremental testing commonly used in industry.Peer reviewe

To grind or not to grind? The influence of mechanical and thermal treatments on the Cu Zn disorder in Cu2ZnSn SxSe1 x 4 monograins

Kesterite type based thin film solar cell technologies are mainly based on polycrystalline absorber layers. A promising low cost alternative technology uses Cu2ZnSn SxSe1 x 4 CZTSSe monograins single crystals of 20 100 amp; 956;m size which are fixed in a polymer matrix to form a flexible solar cell. The Cu Zn disorder is discussed as a possible reason for band tailing causing voltage losses limiting the efficiency of CZTSSe based devices. The experimental determination of the order parameter Q which is a quantitative measure of Cu Zn disorder, requires a differentiation between the isoelectronic cations Cu and Zn2 . An in depth analysis of neutron diffraction data allows the determination of type and concentration of intrinsic point defects including a distinction between Cu and Zn. Neutron diffraction requires large sample volumes, thus monograins offer the unique possibility to correlate structural disorder in CZTSSe with device performance parameters. In this study we tackle the influence of grinding the monograins on stoichiometry deviations, the Cu Zn disorder as well as intrinsic point defects and optoelectronic properties of CZTSSe monograins. Moreover, an easy methodology based on Raman scattering spectroscopy is proposed for the assessment of Cu Zn disorder in the CZTSSe compound