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Nanographenes are emerging as a distinctive class of functional materials for electronic and optical devices. Here, the authors develop a facile strategy to recompose helicenes into a variety of chiral nanographenes through an oxidative cyclo-rearrangement reaction.

Abstract The calculation of magnetic transition dipole moments and rotatory strengths was implemented at the zeroth‐order regular approximation (ZORA) two‐component relativistic time‐dependent density functional theory (TDDFT) level. The circular dichroism of the spin‐forbidden ligand‐field transitions of tris(ethylenediamine)cobalt(III) computed in this way agrees very well with available measurements. Phosphorescence dissymmetry factors glum and the corresponding lifetimes are evaluated for three N‐heterocyclic‐carbene‐based iridium complexes, two of which contain helicene moieties, and for two platinahelicenes. The agreement with experimental data is satisfactory. The calculations reproduce the signs and order of magnitude of glum , and the large variations of phosphorescence lifetimes among the systems. The electron spin contribution to the magnetic transition dipole moment is shown to be important in all of the computations.

Vibrational circular dichroism (VCD) spectroscopy can be useful for determining the absolute configuration of chiral molecules, as long as the signal intensities are high enough. Here, the authors establish the absolute configurations of two large chiral porphyrin cages and, notably, discover that host-guest binding enhances their VCD intensities.

This short paper describes the preparation of thin layers based on carbohelicenes, which are inherently chiral polyaromatics existing in the enantiomeric forms P and M. Specifically, [5]-, [6]- and [7]helicene were subjected to redox cycling between −1.5 and 1.5 V vs. ferrocene/ferrocenium at a scan rate of 10 V/s. This way, enantiopure layers exhibiting redox activity were formed on the surfaces of the glassy carbon and ITO electrodes under anoxic and non-aqueous conditions. The properties of the prepared polymer layers were investigated using electrochemistry with Fe/Ru redox probes, circular dischroism, AFM, impedance measurement and Raman spectroscopy. With [6]helicene, the suggested electropolymerization procedure thus represents a proof-of-concept for the preparation of chiral carbonaceous surfaces. Keywords: Carbohelicene, Hexahelicene, Voltammetry, Enantiopure, Redox active, Chiral carbon

Chiral diketopyrrolopyrrole (DPP)-helicene polymers were synthesized to develop efficient red circularly polarized (CP) light emitters. These original chiral dyes display intense electronic circular dichroism (ECD) and CP luminescence (CPL) in the far-red spectral region owing to the presence of excitonic coupling between achiral DPPs within the chiral environment of the polymeric structure. This work affords an interesting example illustrating the potential of π-conjugated helical polymers for chiral optoelectronic applications.

Abstract Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions ϕ eff above close packing (ϕ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above ϕ cp using the zero average contrast method in small-angle neutron scattering. We complement these experiments with measurements of the average interparticle distances using small-angle x-ray scattering, and a determination of the glass transition using dynamic light scattering. This allows us to unambiguously decouple interaction effects from density-dependent variations of the particle size and shape at all values of ϕ eff . We demonstrate that the microgels used in this study significantly interpenetrate and thus change their size and shape only marginally even for ϕ eff ≫ ϕ cp , a finding that may require changes in the interpretation of a number of previously published studies on the structural and dynamic properties of dense soft particle systems.

BackgroundGuanylyl cyclase, a heme‐containing α1β1 heterodimer (GC1), produces cGMP in response to Nitric oxide (NO) stimulation. The NO‐GC1‐cGMP pathway negatively regulates cardiomyocyte contractility and protects against cardiac hypertrophy–related remodeling. We recently reported that the β1 subunit of GC1 is detected at the intercalated disc with connexin 43 (Cx43). Cx43 forms gap junctions (GJs) at the intercalated disc that are responsible for electrical propagation. We sought to determine whether there is a functional association between GC1 and Cx43 and its role in cardiac homeostasis. Methods and ResultsGC1 and Cx43 immunostaining at the intercalated disc and coimmunoprecipitation from membrane fraction indicate that GC1 and Cx43 are associated. Mice lacking the α subunit of GC1 (GCα1 knockout mice) displayed a significant decrease in GJ function (dye‐spread assay) and Cx43 membrane lateralization. In a cardiac‐hypertrophic model, angiotensin II treatment disrupted the GC1‐Cx43 association and induced significant Cx43 membrane lateralization, which was exacerbated in GCα1 knockout mice. Cx43 lateralization correlated with decreased Cx43‐containing GJs at the intercalated disc, predictors of electrical dysfunction. Accordingly, an ECG revealed that angiotensin II–treated GCα1 knockout mice had impaired ventricular electrical propagation. The phosphorylation level of Cx43 at serine 365, a protein‐kinase A upregulated site involved in trafficking/assembly of GJs, was decreased in these models. ConclusionsGC1 modulates ventricular Cx43 location, hence GJ function, and partially protects from electrical dysfunction in an angiotensin II hypertrophy model. Disruption of the NO‐cGMP pathway is associated with cardiac electrical disturbance and abnormal Cx43 phosphorylation. This previously unknown NO/Cx43 signaling could be a protective mechanism against stress‐induced arrhythmia.

While there is extensive literature on the influence of both compressive and tensile strain on the domain patterns of (001) tetragonal ferroelectric thin films, little is known regarding domain engineering in (110) films. The primary reason is the absence of suitable substrates that allow the growth of epitaxial films with this orientation. However, recent works emphasized the importance of this orientation with the possibility for e.g. to achieve ultra-high ferroelectric domain density. This work reports the controlled growth of a/c domain patterns in highly tetragonal monocrystalline (110) oriented Pb(Zr0.05, Ti0.95)O3. It is demonstrated that while a/c patterns can easily be realized in the single layer film relaxed under compressive misfit strain, modulation of tensile misfit strain through the use of buffer layers allows for consistent control of domain periodicity, in which case the average domain period was tuned between 630 and 60 nm. The effects of domain density and defects on both switching behavior and piezoelectric properties in single and multilayered structures are also investigated, revealing an optimum composition of the buffer layer for improved domain compliance and piezoelectric properties.

Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use version 1.0 which describes these interactions through a generic representation of agricultural intensification mechanisms within agricultural lands. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs such as industrial fertilisers; (ii) a detailed representation of the livestock production system subdivided into an intensive and an extensive component, and (iii) a spatially explicit distribution of potential (maximal) crop yields prescribed from the Lund-Postdam-Jena global vegetation model for managed Land (LPJmL). The economic principles governing decisions about land-use and intensification are adapted from the Ricardian rent theory, assuming cost minimisation for farmers. In contrast to the other land-use models linking economy and biophysics, crops are aggregated as a representative product in calories and intensification for the representative crop is a non-linear function of chemical inputs. The model equations and parameter values are first described in details. Then, idealised scenarios exploring the impact of forest preservation policies or rising energy price on agricultural intensification are described, and their impacts on pasture and cropland areas are investigated.

An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion). Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG), within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG) and Halobacteria) within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria within Proteobacteria phylum, and also members of Bacteroidetes phylum. The second most abundant lineages were Actinobacteria and Firmicutes at the Gulf of Lion site and Chloroflexi at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: Alpha-, Gammaproteobacteria, Firmicutes and Actinobacteria. In molecular surveys, the Betaproteobacteria group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea levee. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence analyses (CCA) showed that the availability of electron acceptors and the quality of electron donors (indicated by age) strongly influenced the community structure. In contrast, within the Gulf of Lion core, characterized by a homogeneous lithological structure of upper-slope environment, most detected groups were Bacteroidetes and, to a lesser extent, Betaproteobacteria. At both site, the detection of Betaproteobacteria coincided with increased terrestrial inputs, as confirmed by the geochemical measurements (Si, Sr, Ti and Ca). In the Gulf of Lion, geochemical parameters were also found to drive microbial community composition. Taken together, our data suggest that the palaeoenvironmental history of erosion and deposition recorded in the Western Mediterranean Sea sediments has left its imprint on the sedimentological context for microbial habitability, and then indirectly on structure and composition of the microbial communities during the late Quaternary.

The complexes [Ln2(hfac)6(L)]·nC6H14 (Ln = Dy (1) n = 0, Yb (2) n = 1) with the L chiral 3,14-di-(2-pyridyl)-4,13-diaza[6]helicene ligand (hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate) have been synthesized in their racemic form and structurally and magnetically characterized. Both complexes behave as field-induced single molecule magnets in the crystalline phase. These magnetic properties were rationalized by ab initio calculations.

Numerical simulations performed to complement experimental studies of a biaxial test show that stress and strain are both structured at the mesoscopic scale. Certain features can be explained by a calculation from linear elasticity.

We present an experimental investigation of the formation of shear bands in a granular sample submitted to a biaxial test. Our principal result is the direct observation of the bifurcation at the origin of the localization process in the material. At the bifurcation, the shear band is spatially extended: we observe a breaking of symmetry without any sudden localization of the deformation in a narrow band. Our work thus allows to clearly distinguish different phenomena: bifurcation which is a ponctual event which occurs before the peak, localization which is a process that covers a range of deformation of several percents during which the peak occurs and finally stationary shear bands which are well-defined permanent structures that can be observed at the end of the localization process, after the peak.

Research on Atlantic Ocean hydrothermal vents around the Azores plateau suggests that vent fluid toxicity changes and suspended mineral particles produce composition and structure variations in hydrothermal vent communities at the depth gradient. Vents included in the study were the Rainbow, Menez Gwen and Lucky Strike vents.

Diffusive Wave Spectroscopy is used to measure very small strains of the order of 10−5 − 10−3. That method gives a new full-field measurement of the strain at the vicinity of the surface of highly scattering materials. The principle of the method is presented and application to the measurement of micro-deformations in a granular material are shown.