Conjugated compounds for molecular electronics: from synthesis to conductance studies.

This project concerns the synthesis and characterization of linear conjugated compounds, and assessment of their electrical performance. To that end, several oligo(phenylene-ethynylene)s (OPEs) were prepared and the available synthetic procedures reviewed and optimized. Monolayers of these compounds were transferred onto solid substrates by means of the Langmuir-Blodgett technique, and their physical and electrical properties evaluated by Atomic Force Microscopy (AFM) and Scanning Tunnelling Microscopy (STM). Two novel approaches to the formation of the top electrode on sandwich like metal|molecule|metal devices, based on the in-situ decomposition of gold complexes, are detailed. The synthetic methodologies appropriate for the preparation of gold ethynyl complexes Au(C≡CR)(L) (R = aryl, L= PPh3 and CNR) that are critical to the thermal and photochemical decomposition protocol are described. A convenient synthesis of bis(ethynyl) complexes trans-Ru(CCR)2(dppe)2 and unsymmetrically substituted derivatives trans-Ru(CCR1)(CCR2)(dppe)2 is described. A detailed structural and spectroelectrochemical study of the complexes, supported by TD-DFT calculations, demonstrated the relationships between the underlying electronic transitions that are responsible for the NIR absorption band shape and the relative orientations of the metal fragment and arylethynyl moieties in the oxidized species. Single molecule STM conductance studies were performed on a series of OPE and polyyne derivatives devoting special attention to the role of the molecular linker in the overall performance of the molecular junction. In that regard, a novel molecular linker CCSiMe3 was introduced and its electrical and mechanical properties benchmarked against literature known molecular anchoring groups i.e. NH2 and SH. Transistor-like behaviour was observed in preliminary electrochemical STM studies performed on complex Ru(CCC6H4CCSiMe3)2(dppe)2. Finally, the statistical treatment of the conductance (STM) and force (AFM) measurements and the Visual Basic (VBA) codes designed to analyse the large datasets collected are included

Electrically transmissive alkyne-anchored monolayers on gold

Well-ordered, tightly-packed (surface coverage 0.97 × 10−9 mol cm−2) monolayer films of 1,4-bis((4-ethynylphenyl)ethynyl)benzene (1) on gold are prepared via a simple self-assembly process, taking advantage of the ready formation of alkynyl C–Au σ-bonds. Electrochemical measurements using [Ru(NH3)6]3+, [Fe(CN)6]3−, and ferrocenylmethanol [Fe(η5-C5H4CH2OH)(η5-C5H5)] redox probes indicate that the alkynyl C–Au contacted monolayer of 1 presents a relatively low barrier for electron transfer. This contrasts with monolayer films on gold of other oligo(phenylene ethynylene) derivatives of comparable length and surface coverage, but with different contacting groups. Additionally, a low voltage transition (Vtrans = 0.51 V) from direct tunneling (rectangular barrier) to field emission (triangular barrier) is observed. This low transition voltage points to a low tunneling barrier, which is consistent with the facile electron transport observed through the C–Au contacted self-assembled monolayer of 1.P. C. and J. L. S. are grateful for financial assistance from Ministerio de Economia y Competitividad from Spain and fondos FEDER in the framework of projects MAT2016-78257-R and CTQ2015-70174-P, respectively. J. L. S. also acknowledges the funded project Hierarchical Self Assembly of Polymeric Soft Systems, “SASSYPOL”, from the 7th Framework Programme (CEE, Ref-607602). L. H., S. M., J. L. S, and P. C. acknowledge support from DGA/Fondos FEDER (construyendo Europa desde Aragón) for funding PLATON (E31_17R) and CLIP (E47_17R) research groups. R. J. N. thanks EPSRC for funding (EP/M029522/1, EP/K007785/1, EP/M014169/1 and EP/M005046/1), and P. J. L. also gratefully acknowledges support from the Australian Research Council (FT120100073; DP140100855).Peer reviewe

Towards a metallic top contact electrode in molecular electronic devices exhibiting a large surface coverage by photoreduction of silver cations

In this contribution the photoreduction of silver ions coordinated onto a Langmuir–Blodgett monolayer is presented as an effective method for the deposition of the top contact electrode in metal/monolayer/metal devices. Silver cations were incorporated from an aqueous AgNO3 sub-phase of Langmuir films of 4,4'-(1,4-phenylenebis(ethyne-2,1-diyl))dibenzoic acid upon the transference of these films onto a metallic substrate. Subsequent irradiation of the silver-ion functionalized Langmuir–Blodgett films with 254 nm light results in the photoreduction of silver cations to produce metallic silver nanoparticles, which are distributed over the organic monolayer and exhibit a surface coverage as large as 76% of the monolayer surface. Electrical properties of these metal/monolayer/metal devices were determined by recording I–V curves, which show a sigmoidal behaviour indicative of well-behaved junctions free of metallic filaments and short-circuits. The integrity of the organic monolayer upon the irradiation process and formation of the silver top-contact electrode has also been demonstrated through cyclic voltammetry experiments

CXCL6 is an important paracrine factor in the pro-angiogenic human cardiac progenitor-like cell secretome

Studies in recent years have established that the principal effects in cardiac cell therapy are associated with paracrine/autocrine factors. We combined several complementary techniques to define human cardiac progenitor cell (CPC) secretome constituted by 914 proteins/genes; 51% of these are associated with the exosomal compartment. To define the set of proteins specifically or highly differentially secreted by CPC, we compared human mesenchymal stem cells and dermal fibroblasts; the study defined a group of growth factors, cytokines and chemokines expressed at high to medium levels by CPC. Among them, IL-1, GROa (CXCL1), CXCL6 (GCP2) and IL-8 are examples whose expression was confirmed by most techniques used. ELISA showed that CXCL6 is significantly overexpressed in CPC conditioned medium (CM) (18- to 26-fold) and western blot confirmed expression of its receptors CXCR1 and CXCR2. Addition of anti-CXCL6 completely abolished migration in CPC-CM compared with anti-CXCR2, which promoted partial inhibition, and anti-CXCR1, which was inefficient. Anti-CXCL6 also significantly inhibited CPC CM angiogenic activity. In vivo evaluation also supported a relevant role for angiogenesis. Altogether, these results suggest a notable angiogenic potential in CPC-CM and identify CXCL6 as an important paracrine factor for CPC that signals mainly through CXCR2.This study was supported by funding from the European Commission (HEALTH-2009_242038) and by grants from the Spanish Ministry of Science and Innovation (SAF2012-34327 and SAF2015-70882-R to AB and BIO2012-37926 and BIO2015-67580-P to JV), the Research Program of the Comunidad Autónoma de Madrid (S2010/BMD-2420) and the Instituto de Salud Carlos III (RETICS-RD12/0019/0018 to AB and RETICS-RD12/0042/0056 to JV).S

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median $z\sim 0.03$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $z\sim 0.6$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July

Sloan Digital Sky Survey IV: mapping the Milky Way, nearby galaxies, and the distant universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median $z\sim 0.03$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $z\sim 0.6$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July