Neutron diffraction study of mechanically alloyed and <i>in situ</i> annealed Al₇₅Mo₂₅ powders

The mechanical treatment of a Al75Mo25 mixture of pure elemental powders in a high-energy mixer mill induces partial solid state reactivity and solid solution formation. This is suggested by a quantitative phase evaluation and by the changes of Al lattice parameter carried out with Rietveld analysis of diffraction patterns collected after extended time of processing (4, 8, 16, 32, 57, and 78 h). The small angle neutron scattering experiments showed that diffusion processes are the rate-controlling step for these solid state reactions. The formation of metastable phases is confirmed by in situ neutron diffraction annealing experiments on selected as-milled powders. In the specimen mechanically alloyed for 4 h, Al12Mo phase is formed at 590 °C (below the aluminum melting point). Soon after this temperature, the remaining Al is consumed to form the Al8Mo3 phase. In the alloy mechanically treated for 32 h, the Al12Mo phase appears after annealing at 430 °C, while the Al8Mo3 phase is found at 493 °C. After the disappearance of Al12Mo phase (500 °C), the solid state reaction proceeds to form a new tetragonal Al3Mo phase, not reported in the equilibrium phase diagram. In the specimen mechanically treated for 57 h, the total formation of Al8Mo3 is recorded at 430 °C. Conversely, in the powder ball milled for 78 h, the Al8Mo3 phase appears at 390 °C and coexists with tetragonal Al3Mo

Characterization of nanoporous lanthanide-doped gadolinium gallium garnet powders obtained by propellant synthesis

In the present work we study the nanocrystalline powders of lanthanide-doped Gd3Ga5O12 (GGG, gadolinium gallium garnet) prepared using propellant synthesis. A series of GGG samples containing a number of different trivalent lanthanide ions (Tm, Er, Ho, Eu, Sm, Nd, and Pr) in different quantities (1%, 5%, 10%) were produced. Samples were characterized by X-ray diffraction (pre- and post calcination) for phase identification and line-broadening analysis, and by electron microscopy (SEM and TEM) for morphological and nanostructural investigation. Thermal behavior of the powder was investigated by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The samples have a polycrystalline porous structure. Elemental microanalysis made by energy dispersive X-ray spectroscopy (EDX) detector attached to TEM and XRD unit-cell determinations confirmed that the lanthanides ions entered the structure of GGG. Crystallites have a high degree of disorder

Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant Stabilized Pd Nanoparticles

We report a facile, inexpensive and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable times. The aqueous Pd nanoparticles solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes and -ketones leading to complete conversion to the deoxygenated products even in the absence of strong Brønsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semi-hydrogenation of alkynes leading to alkenes and in the efficient hydro-dechlorination of aromatic substrates. In all cases the micellar media were crucial to stabilize the metal nanoparticles, to dissolve substrates, to steer product selectivity and to enable recycling. What is interesting is also that a benchmark catalyst like Pd/C can be often surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions

Copper Indium Sulfide Quantum Dots as Nanomanometers: Influence of Size and Composition

Mechanical forces control the function of organisms and mediate theinteraction between biological systems and their environments. Knowledge ofthese forces will increase the understanding of biological processes and cansupport the development of novel diagnostic and therapeutic procedures.Although techniques like atomic force microscopy and droplet insertionmethod allow measuring forces over a broad range of values, they are invasiveand lack versatility. A promising way to overcome these hurdles isluminescent nanomanometry. Quantum dots (QDs) specifically have opticalproperties that depend on their size because of the quantum confinement,which makes them responsive to applied forces. Yet, a fine understanding ofhow fundamental parameters affect the response to applied stress is requiredbefore a QD family can be credibly proposed as luminescentnanomanometers. Here, a thorough study is conducted on how size andstoichiometry affect the nanomanometry performance of CuInS2QDs. Thestudied QDs feature pressure-dependent photoluminescence in thered/near-infrared range, which can enable the measurement of mechanicalforces in the range of physiological relevance in a remote and minimallyinvasive way. It is shown that tuning size and stoichiometry cansimultaneously enhance the CuInS2QDs’ brightness and response to appliedpressure, thus providing guidelines for better luminescent nanomanometers

Triphasic liquid systems: generation and segregation of catalyticallyactive Pd nanoparticles in an ammonium-based catalyst-philic phase

A triphasic liquid system fabricated from isooctane, aqueous base, and trioctylmethylammonium chloride/decanol promoted the formation of Pd-nanoparticles in the size range of 2–4 nm which remained immobilised in the onium phase, catalysed organic reactions, and could be recycled

Etest® versus broth microdilution for ceftaroline MIC determination with Staphylococcus aureus: results from PREMIUM, a European multicentre study

Objectives: To compare the concordance of ceftaroline MIC values 24 by reference broth microdilution (BMD) and Etest (BioMérieux, France) for MSSA and MRSA isolates, respectively, in isolates from PREMIUM (D372SL00001), a European multi-centre study.  Methods: Ceftaroline MICs were determined by reference BMD and by Etest for 1,242 MSSA and MRSA from adult patients with community-acquired pneumonia or complicated skin and soft tissue infections collected between February and May 2012; tests were performed across six European laboratories. Selected isolates with ceftaroline resistance in broth (MIC >1 mg/L) were retested in three central laboratories to confirm their behaviour.  Results: Overall concordance between BMD and Etest was good, with >97% essential agreement and >95% categorical agreement. Nevertheless, 12 of the 26 MRSA isolates found resistant by BMD scored as susceptible by Etest, with MICs ≤1 mg/L, thus counting as very major errors, whereas only five of 380 MRSA found ceftaroline susceptible in BMD were mis-categorised as resistant by Etest. Twenty-one of the 26 isolates with MICs of 2 mg/L by BMD were then re-tested twice by each of three central laboratories: BMD MICs of 2 mg/L were consistently found for 19 of the 21 isolates. Among 147 Etest results for these 21 isolates (original plus six repeats per isolate) 112 were >1 mg/L.  Conclusions: BMD and Etest have good overall agreement for ceftaroline against Staphylococcus aureus; nevertheless, reliable Etest-based discrimination of the minority of ceftaroline-resistant (MIC 2 mg/L) MRSA is extremely challenging, requiring careful reading of strips, ideally with duplicate testing

Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands