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The accurate estimation of the subgrade resilient modulus MR is a crucial element in designing durable and resilient pavements as it quantifies the soil’s bearing capacity to withstand traffic loads without excessive deformation or failure. Conventional methods and devices that are used to estimate MR, such as the Falling Weight Deflectometer (FWD) have several limitations due to operational and security constraints when measuring at the network level. To overcome these limitations, Traffic Speed Deflectometer (TSD) has been developed, which can continuously assess the pavement bearing capacity without requiring traffic control. However, processing the massive amounts of data generated by TSD requires specialized processing techniques such as Machine Learning (ML). Therefore, the primary objective of this paper is to develop an efficient and effective model that can accurately estimate MR by combining two techniques: (TSD + ML). The study uses numerical simulations of deflection velocity slope SV under TSD as the forward model. The research employs Support Vector Machine (SVM) algorithm for ML to classify and estimate MR modulus values from a synthetic and controlled dataset. SVM model exhibits robust performance in both classification and regression analysis, whereas, 95% of the discrepancies between estimated and tested values did not exceed ±15MPa. Advanced numerical validation, sensitivity analysis and parameter estimation methods were also conducted to optimize the model’s performance. Overall, the approach proposed in this paper has the potential to make a significant impact in the field of subgrade evaluation and can facilitate the development of better road infrastructure.

Abstract The second law of thermodynamics leaves no doubt that life on planet Earth and its inherent substantial decrease in entropy is fundamentally based on mechanisms converting environmental free energy into the spatial and temporal order of metabolic processes. This argument holds for present life as much as it does for its very beginnings some 4 billion years ago. In this contribution, we try to strip down free energy conversion in extant life (known as “bioenergetics” to the biologists) to its basic principles with the aim to potentially retrodict the nature of the pre‐biotic precursor which drove life into existence. We demonstrate that these basic principles are deeply rooted in aqueous electrochemistry and strongly rely on inorganic redox compounds. The question of life's emergence, generally considered to fall into the realm of organic chemistry, should therefore rather be recognized as an electrochemical problem and its ultimate elucidation will need to strongly implicate the community of electrochemical scientists.

Arsenic is a widely distributed environmental toxin whose presence in drinking water poses a threat to >140 million people worldwide. The respiratory enzyme arsenite oxidase from various bacteria catalyses the oxidation of arsenite to arsenate and is being developed as a biosensor for arsenite. The arsenite oxidase from Rhizobium sp. str. NT-26 (a member of the Alphaproteobacteria) is a heterotetramer consisting of a large catalytic subunit (AioA), which contains a molybdenum centre and a 3Fe-4S cluster, and a small subunit (AioB) containing a Rieske 2Fe-2S cluster. Stopped-flow spectroscopy and isothermal titration calorimetry (ITC) have been used to better understand electron transfer through the redox-active centres of the enzyme, which is essential for biosensor development. Results show that oxidation of arsenite at the active site is extremely fast with a rate of >4000s-1 and reduction of the electron acceptor is rate-limiting. An AioB-F108A mutation results in increased activity with the artificial electron acceptor DCPIP and decreased activity with cytochrome c, which in the latter as demonstrated by ITC is not due to an effect on the protein-protein interaction but instead to an effect on electron transfer. These results provide further support that the AioB F108 is important in electron transfer between the Rieske subunit and cytochrome c and its absence in the arsenite oxidases from the Betaproteobacteria may explain the inability of these enzymes to use this electron acceptor.

The metabolic process of purple sulphur bacteria's anoxygenic photosynthesis has been primarily studied in Allochromatium vinosum, a member of the Chromatiaceae family. However, the metabolic processes of purple sulphur bacteria from the Ectothiorhodospiraceae and Halorhodospiraceae families remain unexplored. We have analysed the proteome of Halorhodospira halophila, a member of the Halorhodospiraceae family, which was cultivated with various sulphur compounds. This analysis allowed us to reconstruct the first comprehensive sulphur‐oxidative photosynthetic network for this family. Some members of the Ectothiorhodospiraceae family have been shown to use arsenite as a photosynthetic electron donor. Therefore, we analysed the proteome response of Halorhodospira halophila when grown under arsenite and sulphide conditions. Our analyses using ion chromatography‐inductively coupled plasma mass spectrometry showed that thioarsenates are chemically formed under these conditions. However, they are more extensively generated and converted in the presence of bacteria, suggesting a biological process. Our quantitative proteomics revealed that the SoxAXYZB system, typically dedicated to thiosulphate oxidation, is overproduced under these growth conditions. Additionally, two electron carriers, cytochrome c551/c5 and HiPIP III, are also overproduced. Electron paramagnetic resonance spectroscopy suggested that these transporters participate in the reduction of the photosynthetic Reaction Centre. These results support the idea of a chemically and biologically formed thioarsenate being oxidized by the Sox system, with cytochrome c551/c5 and HiPIP III directing electrons towards the Reaction Centre. [ABSTRACT FROM AUTHOR]

Electron bifurcation is here described as a special case of the continuum of electron transfer reactions accessible to two-electron redox compounds with redox cooperativity. We argue that electron bifurcation is foremost an electrochemical phenomenon based on (a) strongly inverted redox potentials of the individual redox transitions, (b) a high endergonicity of the first redox transition, and (c) an escapement-type mechanism rendering completion of the first electron transfer contingent on occurrence of the second one. This mechanism is proposed to govern both the traditional quinone-based and the newly discovered flavin-based versions of electron bifurcation. Conserved and variable aspects of the spatial arrangement of electron transfer partners in flavoenzymes are assayed by comparing the presently available 3D structures. A wide sample of flavoenzymes is analyzed with respect to conserved structural modules and three major structural groups are identified which serve as basic frames for the evolutionary construction of a plethora of flavin-containing redox enzymes. We argue that flavin-based and other types of electron bifurcation are of primordial importance to free energy conversion, the quintessential foundation of life, and discuss a plausible evolutionary ancestry of the mechanism.

Green routes to prepare or manufacture sustainable building materials have been attracting a lot of attention over the years targeting sustainability issues. In this investigation, for the first time, sludge from the inert mineral part of the construction and demolition waste (RA-S) is used as main raw material in the fabrication of fired bricks for building purposes. Fired bricks fabricated with different dosages of RA-S and earth material (i.e., 0%, 30%, 50%, 70% and 100% by weight) were prepared and evaluated in terms of their properties. The RA-S was characterized and the results showed that it can be classified as a clayey material and richly graded silty sand whereas brick soil can be classified as clayey sand according to the French Standards. XRD analysis revealed that the addition of the RA-S into raw earth material did not cause big changes in the final mineralogical properties of the fired bricks. The compressive strength (CS) test results indicated that the strength of the brick samples (fired at 800°C) increased with the addition of the RA-S from 30% to 70%. The CS of bricks fired at 800°C were 10.2 MPa, 13.2 MPa, and 16.7 MPa after incorporating 30%, 50% and 70% RA-S, respectively. The density of the fired brick slightly reduced with the RA-S addition. The highest strength was attained at the firing temperature of 800°C in relation to the firing temperature of 1000°C. The RA sludge can be used in combination with earth material to fabricate fired bricks, which can meet the requirements of many Standards all over the world. In the light of these results, it is possible to say that the RA-S generated from recycling inert mineral part of construction and demolition waste plant is a promising material to prepare efficient fired bricks that can be successfully employed in the real construction sector.

The second law of thermodynamics leaves no doubt that life on planet Earth and its inherent substantial decrease in entropy is fundamentally based on mechanisms converting environmental free energy into the spatial and temporal order of metabolic processes. This argument holds for present life as much as it does for its very beginnings some 4 billion years ago. In this contribution, we try to strip down free energy conversion in extant life (known as "bioenergetics" to the biologists) to its basic principles with the aim to potentially retrodict the nature of the pre‐biotic precursor which drove life into existence. We demonstrate that these basic principles are deeply rooted in aqueous electrochemistry and strongly rely on inorganic redox compounds. The question of life's emergence, generally considered to fall into the realm of organic chemistry, should therefore rather be recognized as an electrochemical problem and its ultimate elucidation will need to strongly implicate the community of electrochemical scientists. [ABSTRACT FROM AUTHOR]

The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large α subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small β subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc 1 complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc 1 complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tibs.2008.10.005 Byline: Anne-Lise Ducluzeau (1), Robert van Lis (1), Simon Duval (1), Barbara Schoepp-Cothenet (1), Michael J. Russell (2), Wolfgang Nitschke (1) Abstract: Evolutionary histories of enzymes involved in chemiosmotic energy conversion indicate that a strongly oxidizing substrate was available to the last universal common ancestor before the divergence of Bacteria and Archaea. According to palaeogeochemical evidence, O.sub.2 was not present beyond trace amounts on the early Earth. Based on recent phylogenetic, enzymatic and geochemical results, we propose that, in the earliest Archaean, nitric oxide (NO) and its derivatives nitrate and nitrite served as strongly oxidizing substrates driving the evolution of a bioenergetic pathway related to modern dissimilatory denitrification. Aerobic respiration emerged later from within this ancestral pathway via adaptation of the enzyme NO reductase to its new substrate, dioxygen. Author Affiliation: (1) Laboratoire de Bioenergetique et Ingenierie des Proteines, Centre National de la Recherche Scientifique UPR9036, IFR77, 31 chemin Joseph-Aiguier, 13402 Marseille Cedex 20, France (2) Planetary Science and Life Detection, Section 3220, MS:183-601, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA