Reproductive rhythms, variation in operational sex ratio and sexual selection in crustaceans

Operational sex ratio (OSR) has long been considered an important predictor of sexual selection strength. In crustaceans, OSR is primarily dependent upon reproductive rhythms. Herein, we model different conditions of reproductive rhythms to investigate the potential link between OSR and the strength of sexual selection, focusing on sexual traits commonly found in crustacean males. OSR can vary widely over a reproductive season as a result of reproductive rhythms, which limits the accuracy of its estimation based on a small sample. Overall, OSR was still predicted to correlate positively with sexual selection strength across different reproductive rhythms, yet only when males were assumed to experience a reproductive time-out. A review of experimental and field studies focusing on the link between OSR and sexual selection strength in crustaceans generally confirms our predictions. For the few studies failing to find the predicted pattern, we discuss potential causes for that discrepancy and urge future experimental research to specifically test for the effect of male time-out on the strength of sexual selection for male mating traits. Our model provides new predictions about the link between OSR and sexual selection and revives the long-lasting debate about OSR as an accurate estimate of sexual selection strength

Surface organometallic chemistry for ALD growth of ultra-thin films of WS2 and their photo(electro)catalytic performances

SSCI-VIDE+ING+MZH:EQDInternational audienceElongated nanostructures with a high-aspect-ratio are known to strike a balance between large surface area and minimized charge recombination in energy conversion applications.1 Their surface functionalization with a thin catalytic layer can significantly enhance their performance. Atomic Layer Deposition (ALD) is an established method for achieving uniform coating of high-aspect-ratio surfaces with a conformal thin to ultra-thin film. ALD is based on the succession of two (or more) different self-limiting surface reactions. Understanding the surface chemistry during ALD growth, especially in the first cycles, is important for proper selection of suitable precursors, avoidance of undesired by-products, optimization of deposition conditions as well as film quality when ultra-thin films are targeted.1We here introduce a methodology of studying the surface chemistry of an ALD growth of WS2 via modeling the deposition reactions by molecular compounds in solution and on the surface of high-surface-area 3D-type substrates. The molecular model part of this method is inspired by Surface Organometallic Chemistry (SOMC)2, which brings a large range of spectroscopic and analytic tools to gain insight into the mechanism of ALD reactions, as recently shown by our group on ulktra thin film MoS2 growth.3 Bis(tert-butylimido)bis(dimethylamido)tungsten (VI) (BTBMW) and 1,2-ethanedithiol (EDT) served as tungsten and sulfur precursors, respectively. BTBMW was chosen as a tungsten precursor as there was a precedent in the literature (in collaboration with us) showing successful ALD growth of WS2 while coupling with H2S.4 EDT is an interesting sulfur alternative to H2S and provides a robust analytic handle for the molecular level monitoring of the reaction at each half-cycle. Replication of the surface chemistry in solution using a silica model, triphenylsilanol (Ph3SiOH), as well as on high-surface-area 3D silica powder as a model of silicon wafer5,6 adds complementary molecular precision in the ALD modeling. All results are compared and contrasted with the complement XPS and Raman studies that are conducted on wafers, silica powders and triphenylsiloxy derivatives, en route to molecular level comprehension of the very first stages of WS2 growth from W (VI) precursor.The developed ALD growth method was applied onto (semi)conducting 2D substrates like a Ti disk coated with photoactive TiO2 nanotubes. Then, the ALD-modified and pristine Ti disks were measured in photocurrent production tests.References: 1.Bachmann, J. Atomic layer deposition, a unique method for the preparation of energy conversion devices. Beilstein Journal of Nanotechnology vol. 5 245–248 (2014).2.Copéret, C. et al. Surface Organometallic and Coordination Chemistry toward Single-Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities. Chem. Rev. 116, 323–421 (2016).3.Cadot, S. et al. A novel 2-step ALD route to ultra-thin MoS2 films on SiO2 through a surface organometallic intermediate. Nanoscale 9, 538–546 (2017).4.Wu, Y. et al. A Self-Limited Atomic Layer Deposition of WS 2 Based on the Chemisorption and Reduction of Bis( t -butylimino)bis(dimethylamino) Complexes. Chem. Mater. 31, 1881–1890 (2019).5.Sneh, O. & George, S. M. Thermal Stability of Hydroxyl Groups on a Well-Defined Silica Surface. J. Phys. Chem. 99, 4639–4647 (1995).6.Nyns, L. et al. HfO2 Atomic Layer Deposition Using HfCl4/H2O: The First Reaction Cycle. ECS Trans. 16, 257–267 (2019)

Surface organometallic chemistry for ALD growth of ultra-thin films of WS2 and their photo(electro)catalytic performances

SSCI-VIDE+ING+MZH:EQDInternational audienceElongated nanostructures with a high-aspect-ratio are known to strike a balance between large surface area and minimized charge recombination in energy conversion applications.1 Their surface functionalization with a thin catalytic layer can significantly enhance their performance. Atomic Layer Deposition (ALD) is an established method for achieving uniform coating of high-aspect-ratio surfaces with a conformal thin to ultra-thin film. ALD is based on the succession of two (or more) different self-limiting surface reactions. Understanding the surface chemistry during ALD growth, especially in the first cycles, is important for proper selection of suitable precursors, avoidance of undesired by-products, optimization of deposition conditions as well as film quality when ultra-thin films are targeted.1We here introduce a methodology of studying the surface chemistry of an ALD growth of WS2 via modeling the deposition reactions by molecular compounds in solution and on the surface of high-surface-area 3D-type substrates. The molecular model part of this method is inspired by Surface Organometallic Chemistry (SOMC)2, which brings a large range of spectroscopic and analytic tools to gain insight into the mechanism of ALD reactions, as recently shown by our group on ulktra thin film MoS2 growth.3 Bis(tert-butylimido)bis(dimethylamido)tungsten (VI) (BTBMW) and 1,2-ethanedithiol (EDT) served as tungsten and sulfur precursors, respectively. BTBMW was chosen as a tungsten precursor as there was a precedent in the literature (in collaboration with us) showing successful ALD growth of WS2 while coupling with H2S.4 EDT is an interesting sulfur alternative to H2S and provides a robust analytic handle for the molecular level monitoring of the reaction at each half-cycle. Replication of the surface chemistry in solution using a silica model, triphenylsilanol (Ph3SiOH), as well as on high-surface-area 3D silica powder as a model of silicon wafer5,6 adds complementary molecular precision in the ALD modeling. All results are compared and contrasted with the complement XPS and Raman studies that are conducted on wafers, silica powders and triphenylsiloxy derivatives, en route to molecular level comprehension of the very first stages of WS2 growth from W (VI) precursor.The developed ALD growth method was applied onto (semi)conducting 2D substrates like a Ti disk coated with photoactive TiO2 nanotubes. Then, the ALD-modified and pristine Ti disks were measured in photocurrent production tests.References: 1.Bachmann, J. Atomic layer deposition, a unique method for the preparation of energy conversion devices. Beilstein Journal of Nanotechnology vol. 5 245–248 (2014).2.Copéret, C. et al. Surface Organometallic and Coordination Chemistry toward Single-Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities. Chem. Rev. 116, 323–421 (2016).3.Cadot, S. et al. A novel 2-step ALD route to ultra-thin MoS2 films on SiO2 through a surface organometallic intermediate. Nanoscale 9, 538–546 (2017).4.Wu, Y. et al. A Self-Limited Atomic Layer Deposition of WS 2 Based on the Chemisorption and Reduction of Bis( t -butylimino)bis(dimethylamino) Complexes. Chem. Mater. 31, 1881–1890 (2019).5.Sneh, O. & George, S. M. Thermal Stability of Hydroxyl Groups on a Well-Defined Silica Surface. J. Phys. Chem. 99, 4639–4647 (1995).6.Nyns, L. et al. HfO2 Atomic Layer Deposition Using HfCl4/H2O: The First Reaction Cycle. ECS Trans. 16, 257–267 (2019)

Pulsed Laser Deposition of PdCuAu Alloy Membranes for Hydrogen Absorption Study

Finding suitable binary and ternary alloys for hydrogen purification membranes remains a challenge due to the vast compositional range to be studied. In this context, we proposed a new combination of alloy fabrication (as thin film) by pulsed laser deposition (PLD) and subsequent hydrogen solubility characterization by electrochemical <i>in situ</i> X-ray diffraction (E <i>in situ</i> XRD) able to rapidly screen alloys in a broad range of compositions. In this study, we demonstrated the capabilities of this new technique on the PdCuAu system. A FCC solid solution was formed in the full explored composition range (Pd = 15–100 at. %, Cu = 0–80 at. %, Au = 0–30 at. %). Structural reorganization, relieving some strain in the lattice, was observed during the first electrochemical hydrogen–dehydrogenation cycles. Using E <i>in situ</i> XRD to study the hydrogen solubility of PdCuAu alloys, we confirmed that the Pd content in the alloy is the primary parameter driving hydrogen solubility. Replacing Cu with Au slightly enhanced the hydrogen solubility of PdCuAu

Mo(VI) dithiocarbamate with no pre-existing Mo–S–Mo core as an active lubricant additive

International audience(100 words) 1