A model of large-scale proteome evolution

The next step in the understanding of the genome organization, after the determination of complete sequences, involves proteomics. The proteome includes the whole set of protein-protein interactions, and two recent independent studies have shown that its topology displays a number of surprising features shared by other complex networks, both natural and artificial. In order to understand the origins of this topology and its evolutionary implications, we present a simple model of proteome evolution that is able to reproduce many of the observed statistical regularities reported from the analysis of the yeast proteome. Our results suggest that the observed patterns can be explained by a process of gene duplication and diversification that would evolve proteome networks under a selection pressure, favoring robustness against failure of its individual components

CO2 laser beam welding of AM60 magnesium-based alloy

The authors are grateful to FONDERIE MESSIER HONSEL group that provided the as-cast magnesium alloy workpieces. The authors would like also to acknowledge the technical support of Dr. Moraru of the LSIS Laboratory-Arts et Métiers ParisTech-Aix En Provence-France.Magnesium alloys have a 33% lower density than aluminum alloys, whereas they exhibit the same mechanical characteristics. Their application increases in many economic sectors, in particular, in aeronautic and automotive industries. Nevertheless, their assembly with welding techniques still remains to be developed. In this paper, we present a CO2 laser welding investigation of AM60 magnesium-based alloy. Welding parameters range is determinate for the joining of 3 mm thickness sheets. The effects of process parameters including beam power, welding speed, focusing position, and shielding gas flow are studied. Experimental results show that the main parameters that determine the weld quality are the laser beam power, the welding speed, and the shielding gas flow. The focal point position has a minor effect on weld quality, however, it has an influence on melting zone width. For optimized welding parameters, metallurgical observations show that after laser welding of AM60 alloy dendritic microstructure is observed on melting zone after high solidification rate. A small heat affected zone is also detected. Finally, hardness tests indicate that microhardness of the weld is higher than that of base metal

Co-design of aircraft vertical tail and control laws using distributed electric propulsion

International audienceDistributed Electric Propulsion is investigated as a way to increase directional control of aircraft and reduce the vertical tail surface area. A co-design approach is presented where a H ∞ control method is used to both synthesize longitudinal/lateral control law gains and allocation module while sizing the vertical tail surface area and the propeller actuator bandwidth. The variation of the vertical tail surface area is captured throughout a collection of linearized aircraft systems representing different sizes of the vertical tail reassembled in a Linear Fractional Representation. This approach allows a reduction of 60% of the vertical tail surface area while maintaining desired dynamic behaviors with low actuator bandwidth

Towards an Aircraft with Reduced Lateral Static Stability Using Differential Thrust

International audienceIn the context of aircraft drag reduction, we study the possibility of reducing the area ofthe vertical tail using Distributed Electric Propulsion (DEP) while maintaining lateral stabilitywith active Differential Thrust (DT). Distributed Electric Propulsion is usually thought of asa mean to increase aerodynamic efficiency by exploiting the benefic effects of accelerating airaround key parts of the aircraft. However, it can also be seen as a collection of actuationdevices generating additional moments through Differential Thrust. When the engines aredistributed along the lateral axis, the aircraft designer may take advantage of the increase ofcontrol authority on yaw to reduce the static stability or the control authority provided bythe Vertical Tail (VT). This in turn would allow a reduction of vertical tail surface area. Inorder to explore and assess this idea, we suggest a framework to compare flight qualities ofa traditional configuration versus a configuration using Distributed Electric Propulsion andDifferential Thrust. The framework provides information on the flight envelop and stability ofthe aircraft by computing a map of the equilibriums. Thanks to a global approach, it allows tostudy any aircraft or DEP configurations in any flight phase. In addition, a key feature of theframework is the inclusion of the VeDSC[1] method to compute analytically the contribution ofthe vertical tail to lateral stability. It allows to study effects of a 30% reduction of VT surfacearea. Here are presented the first results and potential of using differential thrust to reducethe area of the vertical tail and the reasons for us to continue developing this framework

Semi-continuous mono-digestion of OFMSW and Co-digestion of OFMSW with beech sawdust: Assessment of the maximum operational total solid content

In this study, mono-digestion of the organic fraction of municipal solid waste (OFMSW) and co-digestion of OFMSW with beech sawdust, simulating green waste, were used to investigate the maximum operational total solid (TS) content in semi-continuous high-solids anaerobic digestion (HS-AD). To alleviate substrate overloading in HS-AD, the effluent mass was relatively reduced compared to the influent mass, extending the mass retention time. To this aim, the reactor mass was daily evaluated, permitting to assess the reactor content removal by biogas production. During mono-digestion of OFMSW, the NH3 inhibition and the rapid TS removal prevented to maintain HS-AD conditions (i.e. TS ≥ 10%), without exacerbating the risk of reactor acidification. In contrast, the inclusion of sawdust in OFMSW permitted to operate HS-AD up to 30% TS, before acidification occurred. Therefore, including a lignocellulosic substrate in OFMSW can prevent acidification and stabilize HS-AD at very high TS contents (i.e. 20-30%)

High-solids anaerobic digestion requires a trade-off between total solids, inoculum-to-substrate ratio and ammonia inhibition

Increasing total solids in anaerobic digestion can reduce the methane yield by highly complex bio-physical–chemical mechanisms. Therefore, understanding those mechanisms and their main drivers becomes crucial to optimize this waste treatment biotechnology. In this study, seven batch experiments were conducted to investigate the effects of increasing the initial total solids in high-solids anaerobic digestion of the organic fraction of municipal solid waste. With inoculum-to-substrate ratio = 1.5 g VS/g VS and maximum total solids ≤ 19.6%, mono-digestion of the organic fraction of municipal solid waste showed a methane yield = 174–236 NmL CH4/ g VS. With inoculum-to-substrate ratio ≤ 1.0 g VS/g VS and maximum total solids ≥ 24.0%, mono-digestion experiments acidified. Co-digestion of the organic fraction of municipal solid waste and beech sawdust permitted to reduce the inoculum-to-substrate ratio to 0.16 g VS/g VS while increasing total solids up to 30.2%, though achieving a lower methane yield (117–156 NmL CH4/ g VS). At each inoculum-to-substrate ratio, higher total solids corresponded to higher ammonia and volatile fatty acid accumulation. Thus, a 40% lower methane yield for mono-digestion was observed at a NH3 concentration ≥ 2.3 g N–NH3/kg reactor content and total solids = 15.0%. Meanwhile, co-digestion lowered the nitrogen content, being the risk of acidification exacerbated only at total solids ≥ 20.0%. Therefore, the biodegradability of the substrate, as well as the operational total solids and inoculum-to-substrate ratio, are closely interrelated parameters determining the success of methanogenesis, but also the risk of ammonia inhibition in high-solids anaerobic digestion

Polymorphism genotyping based on loop-mediated isothermal amplification and smartphone detection

[EN] The genotyping of a single-nucleotide polymorphism (SNP) is addressed through methods based on loop-mediated isothermal amplification (LAMP) combined with user-friendly optical read-outs to cover the current demand for point-of-care DNA biomarker detection. The modification of primer design and reaction composition improved the assay selectivity yielding allele-specific results and reducing false-positive frequency. Furthermore, the reduced cost, ease of use and effectiveness of calorimetric detection (solution and hybridisation chip formats) were availed for the image capture by a smartphone, reching high sensitivity. In order to evaluate their discriminating capacities, LAMP-based methods were applied to human samples to genotype a SNP biomarker (rs1954787) located in the GRIK4 gene and related to the treatment response to anti-depressants drugs. Sensitive (limit of detection: 100 genomic DNA copies), reproducible ( < 15% error), fast (around 70 min) and low-cost assays were accomplished. Patient subgroups were correctly discriminated, agreeing with reference sequencing techniques. The achieved analytical performances using the developed amplification-detection principles confirmed the approach potential for point-of-care optical DNA testing.The authors acknowledge the financial support received from the Generalitat Valenciana (Project GVA-PROMETEOII/2014/040 and GRISOLIA/2014/024 Ph.D. grant) and from the Spanish Ministry of Economy and Competitiveness (MINECO CTQ2013-45875-R Project).Yamanaka, E.; Tortajada-Genaro, LA.; Pastor Navarro, N.; Maquieira Catala, A. (2018). Polymorphism genotyping based on loop-mediated isothermal amplification and smartphone detection. Biosensors and Bioelectronics. 109:177-183. https://doi.org/10.1016/j.bios.2018.03.008S17718310

FESDIA (v1.0): exploring temporal variations of sediment biogeochemistry under the influence of flood events using numerical modelling

Episodic events of flood deposit in coastal environments are characterized by deposition of large quantities of sediment containing reactive organic matter within short periods of time. While steady-state modelling is common in sediment biogeochemical modelling, the inclusion of these events in current early diagenesis models has yet to be demonstrated. We adapted an existing model of early diagenetic processes to include the ability to mimic an immediate organic carbon deposition. The new model version (FESDIA) written in Fortran and R programming language was able to reproduce the basic trends from field sediment porewater data affected by the November 2008 flood event in the Rhône River prodelta. Simulation experiments on two end-member scenarios of sediment characteristics dictated by field observation (1–high thickness deposit, with low TOC (total organic carbon) and 2–low thickness, with high TOC), reveal contrasting evolutions of post-depositional profiles. A first-order approximation of the differences between subsequent profiles was used to characterize the timing of recovery (i.e. relaxation time) from this alteration. Our results indicate a longer relaxation time of approximately 4 months for SO42- and 5 months for DIC (dissolved inorganic carbon) in the first scenario, and less than 3 months for the second scenario which agreed with timescale observed in the field. A sensitivity analysis across a spectrum of these end-member cases for the organic carbon content (described as the enrichment factor α) and for sediment thickness indicates that the relaxation time for oxygen, sulfate, and DIC decreases with increasing organic enrichment for a sediment deposition that is less than 5 cm. However, for larger deposits (&gt;14 cm), the relaxation time for oxygen, sulfate, and DIC increases with α. This can be related to the depth-dependent availability of oxidant and the diffusion of species. This study emphasizes the significance of these sediment characteristics in determining the sediment's short-term response in the presence of an episodic event. Furthermore, the model described here provides a useful tool to better understand the magnitude and dynamics of flooding event on biogeochemical reactions on the seafloor.</p

Reduction of Vertical Tail Using Differential Thrust: Influence on Flight Control and Certification

International audienceThe flight control characteristics and certification compliance of a Distributed Electric Propulsion (DEP) aircraft using differential thrust is studied through exploration of flight envelops. Identification of critical flight phases specific to the use of propulsion systems as actuators for flight control is performed. In particular the influence of engine failures on the flight envelop and means of mitigation are given. It is concluded that an aircraft using differential thrust has a most advantageous flight envelop at the point of neutral directional static stability allowing a reduction of 45% of the vertical tail surface area. Additionally, the directional control could be entirely provided by differential thrust, eliminating the need for a rudder. Study of this type of aircraft showed specific failure modes that differ from the actual certification prescriptions. New more relevant definitions and parameters are proposed as basis to demonstrate compliance with high level certification objectives