Electrocatalytic Reduction of C-C π-Bonds via a Cobaltocene-Derived Concerted Proton-Electron Transfer Mediator: Fumarate Hydrogenation as a Model Study.

Reductive concerted proton-electron transfer (CPET) is poorly developed for the reduction of C-C π-bonds, including for activated alkenes that can succumb to deleterious pathways (e.g., a competing hydrogen evolution reaction or oligomerization) in a standard electrochemical reduction.

Phase-Separated Nanophotonic Structures by Inkjet Printing.

The spontaneous phase separation of two or more polymers is a thermodynamic process that can take place in both biological and synthetic materials and which results in the structuring of the matter from the micro- to the nanoscale. For photonic applications, it allows forming quasi-periodic or disordered assemblies of light scatterers at high throughput and low cost. The wet process methods currently used to fabricate phase-separated nanostructures (PSNs) limit the design possibilities, which in turn hinders the deployment of PSNs in commercialized products.

Third-Generation W(CNAr) Photoreductants (CNAr = Fused-Ring and Alkynyl-Bridged Arylisocyanides).

Homoleptic tungsten(0) arylisocyanides possess photophysical and photochemical properties that rival those of archetypal ruthenium(II) and iridium(III) polypyridine complexes. Previous studies established that extending the π-system of 2,6-diisopropylphenylisocyanide (CNDipp) by coupling aryl substituents to the isocyanide functionality results in W(CNDippAr) oligoarylisocyanide complexes with greatly enhanced metal-to-ligand charge transfer (MLCT) excited-state properties relative to those of W(CNDipp). Extending electronic modifications to delineate additional design principles for this class of photosensitizers, herein we report a series of W(CNAr) compounds with naphthalene-based fused-ring (CN-1-(2-Pr)-Naph) and CNDipp-based alkynyl-bridged (CNDippAr) arylisocyanide ligands.

Predicting Thermal Adaptation by Looking Into Populations' Genomic Past.

Molecular evolution offers an insightful theory to interpret the genomic consequences of thermal adaptation to previous events of climate change beyond range shifts. However, disentangling often mixed footprints of selective and demographic processes from those due to lineage sorting, recombination rate variation, and genomic constrains is not trivial. Therefore, here we condense current and historical population genomic tools to study thermal adaptation and outline key developments (genomic prediction, machine learning) that might assist their utilization for improving forecasts of populations' responses to thermal variation.

Embryo size regulates the timing and mechanism of pluripotent tissue morphogenesis.

Mammalian embryogenesis is a paradigm of regulative development as mouse embryos show plasticity in the regulation of cell fate, cell number, and tissue morphogenesis. However, the mechanisms behind embryo plasticity remain largely unknown. Here, we determine how mouse embryos respond to an increase in cell numbers to regulate the timing and mechanism of embryonic morphogenesis, leading to the formation of the pro-amniotic cavity.

Patterned nanofiber air filters with high optical transparency, robust mechanical strength, and effective PM capture capability.

PM, due to its small particle size, strong activity, ease of the attachment of toxic substances and long residence time in the atmosphere, has a great impact on human health and daily production. In this work, we have presented patterned nanofiber air filters with high optical transparency, robust mechanical strength and effective PM capture capability. Here, to fabricate a transparency air filter by a facile electrospinning method, we chose three kinds of patterned wire meshes with micro-structures as negative receiver substrates and directly electrospun polymer fibers onto the supporting meshes.

Design of a Graphene Nitrene Two-Dimensional Catalyst Heterostructure Providing a Well-Defined Site Accommodating One to Three Metals, with Application to CO Reduction Electrocatalysis for the Two-Metal Case.

Recently, the reduction of CO to fuels has been the subject of numerous studies, but the selectivity and activity remain inadequate. Progress has been made on single-site two-dimensional catalysts based on graphene coupled to a metal and nitrogen for the CO reduction reaction (CORR); however, the product is usually CO, and the metal-N environment remains ambiguous. We report a novel two-dimensional graphene nitrene heterostructure (grafiN) providing well-defined active sites (N) that can bind one to three metals for the CORR.

Free-Electron-Bound-Electron Resonant Interaction.

Here we present a new paradigm of free-electron-bound-electron resonant interaction. This concept is based on a recent demonstration of the optical frequency modulation of the free-electron quantum electron wave function (QEW) by an ultrafast laser beam. We assert that pulses of such QEWs correlated in their modulation phase, interact resonantly with two-level systems, inducing resonant quantum transitions when the transition energy ΔE=ℏω_{21} matches a harmonic of the modulation frequency ω_{21}=nω_{b}.

Li-diffusion at the interface between Li-metal and [Pyr][TFSI]-ionic liquid: Ab initio molecular dynamics simulations.

We previously reported comprehensive density functional theory-molecular dynamics (DFT-MD) at 400 K to determine the composition and structure of the solid electrolyte interface (SEI) between a Li anode and [Pyr][TFSI] ionic liquid. In this paper, we examined diffusion rates in both the Li-electrode region and SEI compact layer in smaller 83Li/2[TFSI] and larger 164Li/4[TFSI] systems. At 400 K, the Li-diffusion constant in the Li-region is 1.

Light Enhanced Fe-Mediated Nitrogen Fixation: Mechanistic Insights Regarding H Elimination, HER, and NH Generation.

Despite their proposed accumulation at the Fe sites of the FeMo-cofactor of MoFe-nitrogenase, the presence of hydride ligands in molecular model systems capable of the nitrogen reduction reaction (NRR) appears to diminish the catalytic N-to-NH conversion. We find that for an iron-based system bearing the trisphosphine ligand PP, a dramatic difference in yields is observed for NRR catalyzed by precatalysts with zero, one, or two hydride ligands; however, irradiating the three different catalysts with a mercury lamp results in similar yields. Although the efficacy for NRR versus the hydrogen evolution reaction (HER) is modest for this system by comparison to certain iron (and other metal) catalysts, the system provides an opportunity to study the role of hydrides in the selectivity for NRR versus HER, which is a central issue in catalyst design.

Interface Structure in Li-Metal/[Pyr][TFSI]-Ionic Liquid System from ab Initio Molecular Dynamics Simulations.

Ionic liquids (ILs) are promising materials for application in a new generation of Li batteries. They can be used as electrolyte or interlayer or incorporated into other materials. ILs have the ability to form a stable solid electrochemical interface (SEI), which plays an important role in protecting the Li-based electrode from oxidation and the electrolyte from extensive decomposition.

Cp* Noninnocence Leads to a Remarkably Weak C-H Bond via Metallocene Protonation.

Metallocenes, including their permethylated variants, are extremely important in organometallic chemistry. In particular, many are synthetically useful either as oxidants (e.g.

Fe-mediated HER vs NRR: Exploring Factors that Contribute to Selectivity in P Fe(N) (E = B, Si, C) Catalyst Model Systems.

Mitigation of the hydrogen evolution reaction (HER) is a key challenge in selective small molecule reduction catalysis. This is especially true of catalytic nitrogen (N) and carbon dioxide (CO) reduction reactions (NRR and CORR, respectively) using H/e currency. Here we explore, via DFT calculations, three iron model systems, P Fe (E = B, Si, C), known to mediate both NRR and HER, but with different selectivity depending on the identity of the auxiliary ligand.

Deciphering OPA1 mutations pathogenicity by combined analysis of human, mouse and yeast cell models.

OPA1 is the major gene responsible for Dominant Optic Atrophy (DOA) and the syndromic form DOA "plus". Over 370 OPA1 mutations have been identified so far, although their pathogenicity is not always clear. We have analyzed one novel and a set of known OPA1 mutations to investigate their impact on protein functions in primary skin fibroblasts and in two "ad hoc" generated cell systems: the MGM1/OPA1 chimera yeast model and the Opa1-/- MEFs model expressing the mutated human OPA1 isoform 1.

ENDOR Characterization of (N)Fe(μ-H)Fe(N): A Spectroscopic Model for N Binding by the Di-μ-hydrido Nitrogenase Janus Intermediate.

The biomimetic diiron complex 4-(N), featuring two terminally bound Fe-N centers bridged by two hydrides, serves as a model for two possible states along the pathway by which the enzyme nitrogenase reduces N. One is the Janus intermediate E(4H), which has accumulated 4[e-/H+], stored as two [Fe-H-Fe] bridging hydrides, and is activated to bind and reduce N through reductive elimination (RE) of the hydride ligands as H. The second is a possible RE intermediate.

Author Correction: Strong constraint on modelled global carbon uptake using solar-induced chlorophyll fluorescence data.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Fe-Mediated Nitrogen Fixation with a Metallocene Mediator: Exploring p K Effects and Demonstrating Electrocatalysis.

Substrate selectivity in reductive multielectron/proton catalysis with small molecules such as N, CO, and O is a major challenge for catalyst design, especially where the competing hydrogen evolution reaction (HER) is thermodynamically and kinetically competent. In this study, we investigate how the selectivity of a tris(phosphine)borane iron(I) catalyst, PFe, for catalyzing the nitrogen reduction reaction (NRR, N-to-NH conversion) versus HER changes as a function of acid p K. We find that there is a strong correlation between p K and NRR efficiency.

A novel preparation method for ZnO/γ-AlO nanofibers with enhanced absorbability and improved photocatalytic water-treatment performance by Ag nanoparticles.

A novel method for synthesizing ZnO/γ-Al2O3 nanofibers by electrospinning and subsequent calcination is reported. The prepared nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The ZnO/γ-Al2O3 nanofibers exhibited excellent capacity for adsorbing organics with a negative zeta potential such as methyl orange (95.

Strong constraint on modelled global carbon uptake using solar-induced chlorophyll fluorescence data.

Accurate terrestrial biosphere model (TBM) simulations of gross carbon uptake (gross primary productivity - GPP) are essential for reliable future terrestrial carbon sink projections. However, uncertainties in TBM GPP estimates remain. Newly-available satellite-derived sun-induced chlorophyll fluorescence (SIF) data offer a promising direction for addressing this issue by constraining regional-to-global scale modelled GPP.

Bioinspired phase-separated disordered nanostructures for thin photovoltaic absorbers.

The wings of the black butterfly, , are covered by micro- and nanostructured scales that harvest sunlight over a wide spectral and angular range. Considering that these properties are particularly attractive for photovoltaic applications, we analyze the contribution of these micro- and nanostructures, focusing on the structural disorder observed in the wing scales. In addition to microspectroscopy experiments, we conduct three-dimensional optical simulations of the exact scale structure.

Catalytic N-to-NH Conversion by Fe at Lower Driving Force: A Proposed Role for Metallocene-Mediated PCET.

We have recently reported on several Fe catalysts for N-to-NH conversion that operate at low temperature (-78 °C) and atmospheric pressure while relying on a very strong reductant (KC) and acid ([H(OEt)][BAr]). Here we show that our original catalyst system, PFe, achieves both significantly improved efficiency for NH formation (up to 72% for e delivery) and a comparatively high turnover number for a synthetic molecular Fe catalyst (84 equiv of NH per Fe site), when employing a significantly weaker combination of reductant (Cp*Co) and acid ([PhNH][OTf] or [PhNH][OTf]). Relative to the previously reported catalysis, freeze-quench Mössbauer spectroscopy under turnover conditions suggests a change in the rate of key elementary steps; formation of a previously characterized off-path borohydrido-hydrido resting state is also suppressed.

Generation of mature T cells from human hematopoietic stem and progenitor cells in artificial thymic organoids.

Studies of human T cell development require robust model systems that recapitulate the full span of thymopoiesis, from hematopoietic stem and progenitor cells (HSPCs) through to mature T cells. Existing in vitro models induce T cell commitment from human HSPCs; however, differentiation into mature CD3TCR-αβ single-positive CD8 or CD4 cells is limited. We describe here a serum-free, artificial thymic organoid (ATO) system that supports efficient and reproducible in vitro differentiation and positive selection of conventional human T cells from all sources of HSPCs.

Reliable Identification of Living Dopaminergic Neurons in Midbrain Cultures Using RNA Sequencing and TH-promoter-driven eGFP Expression.

In Parkinson's Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, leading to bradykinesia, rigidity, and tremor. The identification of living dopaminergic neurons in primary Ventral Mesencephalic (VM) cultures using a fluorescent marker provides an alternative way to study the selective vulnerability of these neurons without relying on the immunostaining of fixed cells. Here, we isolate, dissociate, and culture mouse VM neurons for 3 weeks.