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The synthesis of germanium nanoparticles has been carried out, thanks to the design of novel aminoiminate germanium(ii) precursors: (ATI)GeZ (with Z = OMe, NPh2, and ATI = N,N′-diisopropyl-aminotroponiminate) and (Am)2Ge (Am = N,N′-bis(trimethylsilyl)phenyl amidinate). These complexes were fully characterized by spectroscopic techniques as well as single crystal X-ray diffraction. The thermolysis of both complexes yielded NPs which display similar features that are a Ge/GeO2 core/shell structure with a mean diameter close to 5 nm with a narrow size distribution (＜15%). Whereas the high temperatures (＞300 °C) classically reported in the literature for the preparation of germanium-based NPs were necessary for thermolysis of the complexes (ATI)GeZ, the use of amidinate-based precursors allows the preparation at an unprecedented low temperature (160 °C) for the thermolytic route. As suggested by a mechanistic study, the lower reactivity of (ATI)GeZ (for which the concomitant use of high temperature and acidic reagent is required) was explained in terms of lower ring strain compared to the case of (Am)2Ge. [ABSTRACT FROM AUTHOR]

Based on a synthesis strategy of silica nanoparticles (NPs) in non-alcoholic medium, a straightforward protocol leading to strawberry-like SiO2@M nanomaterials (M = Pt, Pd) has been developed. Pd and Pt NPs were immobilised onto surface modified silica NPs, by in situ decomposition of organometallic precursors, Pd2(dba)3 and Pt(dba)2 (dba = dibenzylideneacetone). The surface of silica was functionalised by aminopropyltriethoxysilane (APTES) or 2-(diphenylphosphino)ethyltriethoxysilane (PhPETES). The co-grafting of propyltriethoxysilane (PTES) and APTES was investigated to avoid the classical interfering cohydrolysis and polycondensation reactions which can lead to agglomeration phenomena between the silica NPs. It appeared that a APTES/PTES ratio of 1/3 insured a dense and homogeneous deposition of the metallic NPs onto silica. Depending on the ligand, the diameter of the metallic NPs varies from 3.6 to 6.0 nm for Pd and from 1.5 to 3.1 nm for Pt NPs. The metal loading is adjustable, at least up to 6.91 wt%, as exemplified with Pd. Preliminary catalytic tests of the SiO2@Pd nanomaterial are also presented. [ABSTRACT FROM AUTHOR]

We present here the latest results from experimental studies aiming at measuring the Mass Absorption Coefficient (MAC) of interstellar silicate dust analogues at low temperatures in the far infrared and submillimetre domains which are necessary for the analysis of astronomical data. These results show that above 100µm, the MAC of amorphous silicate nano-grains has a complex dependence with the grain temperature and with the wavelength. This has to be considered when interpreting astronomical observations to avoid errors on the derived parameters such as the dust mass and its physical and chemical properties. [ABSTRACT FROM AUTHOR]

This work features an alternative approach to the well-documented preparation of silica nanoparticles in protic media. We present here the one-pot synthesis of silica nanoparticles of adjustable size (between 18 and 174 nm), prepared and stabilized in organic nonalcoholic solvents. This novel route is based on hydrolysis and condensation of tetraethoxysilane, using water as reactant and different primary amines (butylamine, octylamine, dodecylamine, hexadecylamine) as catalysts in tetrahydrofuran or dimethoxyethane. The growth rate can be finely adjusted, and the first stages of the formation are observed by transmission electronic microscopy, revealing a silicated network in which the silica particles are formed and then released in solution. The amine plays not only a catalyst role but is also implied, as well as the solvent, in the stabilization process and the size control of the particles. A detailed NMR study demonstrates a core−shell structure in which the silica core is surrounded by a layer of alkylammonium ions together with solvent. [ABSTRACT FROM AUTHOR]

Decomposition of the organometallic precursor [Zn(C6H11)2] in wet anisole leads to the formation of monodisperse spherical Zn particles of 6 nm mean diameter. High resolution electron microscopy (HRTEM) indicates the crystalline nature of these particles and photoelectron studies (XPS) are consistent with the presence of both zinc and zinc oxide. In the presence of polyvinylpyrolidone (PVP), the decomposition leads to well dispersed nanoparticles for which HRTEM studies evidenced the presence of hexagonal zinc (0) surrounded by a thin layer of hexagonal zinc oxide of wurtzite type. The thermal oxidation of these zinc nanoparticles yields well-crystallized nanoparticles of ZnO without coalescence or size change. An X-ray diffraction pattern shows that the powder consists of pure hexagonal wurtzite-type phase. [Copyright &y& Elsevier]

The 2014 French Society for Rheumatology (Société Française de Rheumatologie, SFR) recommendations about the management of rheumatoid arthritis (RA) have been updated by a task force composed of 12 expert rheumatologists, 2 patient self-help group representatives, and an occupational therapist. The material used by the task force included recent EULAR recommendations, a systematic literature review, and expert opinion. Four general principles and 15 recommendations were developed. The general principles emphasize the need for shared decision-making between the rheumatologist and the patient and for a global management program including both pharmacological and non-pharmacological treatments. The recommendations deal with the diagnostic strategy for RA, treatment targets, management organization, drug selection based on the treatment line and prognostic factors, management of remissions, and global patient management. Disease-modifying anti-rheumatic drug (DMARD) therapy should be started as early as possible. Validated composite scores should be determined at regular intervals to assess disease activity - according to the tight disease control concept - to achieve the treatment target, i.e., a remission. Methotrexate is the recommended first-line DMARD. The treatment should be optimized when methotrexate is poorly tolerated or inadequately effective. While waiting for conventional synthetic DMARDs to take effect, glucocorticoid therapy can be used, for a brief period to keep the cumulative dose low. When a sustained remission without structural progression is achieved in a patient who is not taking glucocorticoid therapy, targeted therapy de-escalation according to tight disease control principles should be considered. Patients should be periodically screened for comorbidities and their risk factors, which should be evaluated and treated. [ABSTRACT FROM AUTHOR]

Résumé Les précédentes recommandations de 2014 ont été actualisées par un groupe de travail constitué de 12 experts rhumatologues, deux représentants des associations de patients et un professionnel de santé. Le groupe de travail s'est appuyé sur les recommandations de l'EULAR récemment publiées, sur une analyse systématique de la littérature et sur l'avis des experts. Quatre principes généraux et 15 recommandations ont été émis. Les principes généraux mettent en avant l'importance d'une décision partagée entre le rhumatologue et le patient et la nécessité d'une prise en charge globale de la polyarthrite rhumatoïde (PR), sur le plan médicamenteux et non-médicamenteux. Les recommandations concernent l'approche diagnostique de la PR, les objectifs du traitement, l'organisation de la prise en charge, les traitements médicamenteux à utiliser en fonction de la ligne de traitement et des facteurs pronostiques, la gestion de la rémission et la prise en charge globale des patients. Le traitement de fond (disease-modifying antirheumatic drug [DMARD]) doit être initié le plus précocement possible. L'évaluation de l'activité de la maladie par des scores composites validés doit être régulière (contrôle serré) pour atteindre l'objectif thérapeutique (la rémission). Le méthotrexate (MTX) est recommandé en première intention. En cas d'intolérance ou de réponse insuffisante au MTX, le traitement doit être optimisé. En attendant que les DMARDs synthétiques conventionnels soient efficaces, une corticothérapie peut être proposée sur une courte durée afin de garder une dose cumulée faible. En cas de rémission persistante, sans progression structurale, sans corticoïdes, une décroissance progressive des thérapeutiques ciblées respectant les principes du contrôle serré doit être envisagée. Un dépistage et une évaluation périodique des comorbidités, de leurs facteurs de risque et de leur prise en charge doivent être réalisés. [ABSTRACT FROM AUTHOR]

The synthesis of iron germanide nanoparticles at the nanoscale is a challenging task. Here, we describe the preparation of nanocrystals of the hexagonal Fe1.67Ge phase via the thermolysis of single source precursors [{iPrNC(tBu)NiPr}RGe]Fe(CO)4 (where R = Cl, N(SiMe3)2) under mild conditions (200 °C). These bimetallic precursors and the corresponding germylenes [{iPrNC(tBu)NiPr}RGe] were fully characterized by spectroscopic techniques as well as single crystal X-ray diffraction. While the structural features of the molecular species were shown to be almost identical, the results of the thermolysis were highly dependent on the nature of R. When R = Cl, multimodal size distributions and non-controlled phases were obtained. In contrast, the thermolysis of [{iPrNC(tBu)NiPr}{N(SiMe3)2}Ge]Fe(CO)4 yielded pure ferromagnetic Fe1.67Ge nanoparticles with a mean diameter close to 6 nm and a narrow size distribution (＜12%). These results were rationalized in terms of Ge–substituent bond energy thanks to a computational study. [ABSTRACT FROM AUTHOR]

Context. The submillimeter spectral domain has been extensively explored by the Herschel and Planck satellites and is now reachable from the ground with ALMA. A wealth of data, revealing cold dust thermal emission, is available for astronomical environments ranging from interstellar clouds, cold clumps, circumstellar envelops, and protoplanetary disks. The interpretation of these observations relies on the understanding and modeling of cold dust emission and on the knowledge of the dust optical properties. Aims. The aim of this work is to provide astronomers with a set of spectroscopic data of realistic interstellar dust analogues that can be used to interpret the observations. It pursues the experimental effort aimed at characterizing the spectroscopic properties of interstellar dust analogues at low temperature in the mid-infrared (MIR) to millimeter spectral domain. Compared to previous studies, it extends the range of studied dust analogues in terms of composition and of structure of the material. Methods. Glassy silicates of mean composition (1-x)MgO - xSiO2 with x = 0.35 (close to forsterite, Mg2SiO4), 0.50 (close to enstatite, MgSiO3) and 0.40 (close to Mg1.5SiO3.5 or MgSiO3:Mg2SiO4 = 50:50) were synthesized. The mass absorption coefficient (MAC) of the samples was measured in the spectral domain 30-1000 µm for grain temperature in the range 300-10 K and at room temperature in the 5-40 µm domain. Results. We find that the MAC of all samples varies with the grains temperature and that its spectral shape cannot be approximated by a single power law in λβ. In the FIR/submm, and above 30 K, the MAC value at a given wavelength increases with the temperature as thermally activated absorption processes appear. The studied materials exhibit different and complex behaviors at long wavelengths (λ = 200 to 700 µm depending on the samples). These behaviors are attributed to the amorphous nature of dust and to the amount and nature of the defects within this amorphous structure. We do not observe MAC variations in the 10-30 K range. Above 20 µm, the measured MAC are much higher than the MAC calculated from interstellar silicate dust models indicating that the analogues measured in this study are more emissive than the silicates in cosmic dust models. Conclusions. The underestimated value of the MAC deduced from cosmic dust models in the FIR/submm has important astrophysical implications because masses are overestimated by the models. Moreover, constraints on elemental abundance of heavy elements in cosmic dust models are relaxed. [ABSTRACT FROM AUTHOR]

The formation of complex nanostructures combining quantum dots (QDs) and metallic nanoparticles (NPs) opens new perspectives to study and control energy transfer between them, provided that all the phenomena (reabsorption, screening and quenching effect) potentially affecting the photoluminescence (PL) of QDs could be identified and differentiated. First, dilution effect is studied on Cd 3 P 2 QDs and Cd 3 P 2 @ZnS core-shell QDs solutions. The full width at half maximum, the intensity and the emission wavelength are concentration-dependent, while the decay time of PL remains constant in the conditions of measurement. These effects are shown to be fully consistent with the so-called Inner Filter Effect. The addition of Pt NPs to the QD solution causes a clear decrease of the PL intensity which could be attributed to a screening of the emission of QDs by Pt NPs instead of a possible quenching due to an interaction between the two kinds of particles. Potential bias and experimental pitfalls are highlighted to avoid misleading PL interpretations. • The behaviour of photoluminescence emission peak is commonly used. • But experimental pitfalls can lead to misleading photoluminescence interpretation. • Reabsoprtion or screening phenomena can be misleading. • A systematic study of the Cd 3 P 2 and Cd 3 P 2 @ZnS core-shell quantum dots is performed. • Determination of the conditions of work to get reliable PL measurements is crucial. [ABSTRACT FROM AUTHOR]

The facet-dependent surface chemistry of nanocrystals (NCs) provides fundamental insights into chemical reactivities, which are critical for obtaining precise control over the NC surface. In this study, by obtaining InP NCs with well-defined {111} and {110}/{-1-1-1} facets (tetrahedrons and tetrapods, respectively) capped with chloride-oleylamine ligands, the previously underinvestigated facet-dependent surface chemistry of III-V materials is explored. Solid-state and solution NMR analyses show that InP tetrahedrons, with their smaller surface heterogeneity (single facet composition and lesser edge/vertex contribution) and stronger Lewis acidity, exhibit narrow 31 P and 115 In resonances as well as deshielded 13 C signals of α-carbon adjacent to the NH 2 group of oleylamine. As a result, InP tetrahedra exhibit strong ligand binding and a notable presence of less-mobile oleylamine ligands on the surface, leading to the blocking of access to external species. This is also consistent with the minimal blue shift of the first excitonic peak in absorption spectra and the strong resistance to photoassisted surface oxidation of InP tetrahedrons. Our findings, supported by solid-state/solution NMR, FT-IR, and XPS analyses, highlight the significance of facet-dependent reactivities to surface ligands and, thus, atmospheric moieties, enhancing the potential of III-V NCs in various optoelectronic applications.

II-V semiconductor nanocrystals such as Cd 3 P 2 and Zn 3 P 2 have enormous potential as materials in next-generation optoelectronic devices requiring active optical properties across the visible and infrared range. To date, this potential has been unfulfilled due to their inherent instability with respect to air and moisture. Core-shell system Cd 3 P 2 /Zn 3 P 2 is synthesized and studied from structural (morphology, crystallinity, shell diameter), chemical (composition of core, shell, and ligand sphere), and optical perspectives (absorbance, emission-steady state and time resolved, quantum yield, and air stability). The improvements achieved by coating with Zn 3 P 2 are likely due to its identical crystal structure to Cd 3 P 2 (tetragonal), highlighting the key role crystallographic concerns play in creating cutting edge core-shell NCs.

Photoluminescent color conversion by quantum dots (QDs) makes possible the formation of spectrum-on-demand light sources by combining blue LEDs with the light generated by a specific blend of QDs. Such applications, however, require a near-unity photoluminescence quantum efficiency since self-absorption magnifies disproportionally the impact of photon losses on the overall conversion efficiency. Here, we present a synthesis protocol for forming InP-based QDs with +90% quantum efficiency across the full visible spectrum from blue/cyan to red. The central features of our approach are as follows: (1) the formation of InP core QDs through one-batch-one-size reactions based on aminophosphine as the phosphorus precursor, (2) the introduction of a core/shell/shell InP/Zn(Se,S)/ZnS structure, and (3) the use of specific interfacial treatments, most notably the saturation of the ZnSe surface with zinc acetate prior to ZnS shell growth. Moreover, we adapted the composition of the Zn(Se,S) inner shell to attain the intended emission color while minimizing line broadening induced by the InP/ZnS lattice mismatch. The protocol is established by analysis of the QD composition and structure using multiple techniques, including solid-state nuclear magnetic resonance spectroscopy and Raman spectroscopy, and verified for reproducibility by having different researchers execute the same protocol. The realization of full-spectrum, +90% quantum efficiency will strongly facilitate research into light-matter interaction in general and luminescent color conversion in particular through InP-based QDs.