What can the SEDs of first hydrostatic core candidates reveal about their nature?

The first hydrostatic core (FHSC) is the first stable object to form in simulations of star formation. This stage has yet to be observed definitively, although several candidate FHSCs have been reported. We have produced synthetic spectral energy distributions (SEDs) from 3D hydrodynamical simulations of pre-stellar cores undergoing gravitational collapse for a variety of initial conditions. Variations in the initial rotation rate, radius and mass lead to differences in the location of the SED peak and far-infrared flux. Secondly, we attempt to fit the SEDs of five FHSC candidates from the literature and five newly identified FHSC candidates located in the Serpens South molecular cloud with simulated SEDs. The most promising FHSC candidates are fitted by a limited number of model SEDs with consistent properties, which suggests the SED can be useful for placing constraints on the age and rotation rate of the source. The sources we consider most likely to be in FHSC phase are B1-bN, CB17-MMS, Aqu-MM1 and Serpens South candidate K242. We were unable to fit SerpS-MM22, Per-Bolo 58 and Chamaeleon-MMS1 with reasonable parameters, which indicates that they are likely to be more evolved.Comment: 26 pages, 28 figures. Accepted for publication in MNRA

Thermally triggerable, anchoring block copolymers for use in aqueous inkjet printing

Towards the goal of shifting from toxic organic solvents to aqueous-based formulations in commercial inkjet printing, a series of well-defined poly[(2-hydroxyethyl acrylate-stat-N-hydroxymethyl acrylamide)-block-propyl methacrylate], P[(HEA-st-HMAA)-b-PMA], amphiphilic block copolymers with varying degrees of polymerization and comonomer compositions were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Optimized RAFT polymerization conditions were found to allow larger batch synthesis (>20 g scale) without compromise over molecular design control (molecular mass, hydrophobic/hydrophilic balance, dispersity, etc.). The copolymers were subsequently investigated for their crosslinking and adhesive properties, as well as jetting performance, to determine their suitability for use in aqueous ink formulations. Crosslinking was found to occur much faster for copolymers containing more of the crosslinkable HMAA monomer units and at higher molecular masses, allowing control over the required post-deposition processing time. The amphiphilic block copolymers synthesized herein demonstrate enhanced adhesive properties compared to a selection of commercial inks whilst also achieving high print quality and performance for use in aqueous continuous inkjet (CIJ) printing, which is a key step towards greener processes in the packaging industries, where printing onto hydrophobic substrates is needed

The science case for the Planet Formation Imager (PFI)

archiveprefix: arXiv primaryclass: astro-ph.IM eid: 914611 adsurl: http://adsabs.harvard.edu/abs/2014SPIE.9146E..11K adsnote: Provided by the SAO/NASA Astrophysics Data SystemAmong the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work has already been, and is still being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project (PFI; http://www.planetformationimager.org) has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planethosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI. For this purpose, we briefly review our knowledge about the planet-formation process and discuss recent observational results that have been obtained on the class of transition disks. Spectro-photometric and multi-wavelength interferometric studies of these systems revealed the presence of extended gaps and complex density inhomogeneities that might be triggered by orbiting planets. We present detailed 3-D radiation-hydrodynamic simulations of disks with single and multiple embedded planets, from which we compute synthetic images at near-infrared, mid-infrared, far-infrared, and sub-millimeter wavelengths, enabling a direct comparison of the signatures that are detectable with PFI and complementary facilities such as ALMA. From these simulations, we derive some preliminary specifications that will guide the array design and technology roadmap of the facility

Cell–substrate interactions lead to internalization and localization of layered MoS₂ nanosheets

Using an ultrathin film substrate, the first internalization of MoS2 nanosheets through mechanotransduction is demonstrated. The usual method of dispersing nanomaterials in the media limits interactions to random, serendipitous surface contact, and the nanoparticles must be dispersible in media. A substrate approach means that cells directly engage with the nanomaterial, sensing and adhering through sustained interaction and actively internalizing the nanomaterial. This activates previously unobserved cell–substrate mechanotransduction mechanisms and receptor-mediated uptake pathways. Moreover, a wide variety of nonsoluble nanomaterials can be used, improving control over the amount of material exposed to a cell through tunable deposition density. Volumetric Raman mapping demonstrates localization of material to the endoplasmic reticulum, a historically hard-to-target region. The nanosheets do not cause cytotoxicity, are transferred to daughter cells, and have applicability across multiple cell lines. The innate fluorescence or Raman signal of the nanosheet can be utilized for live cell imaging, and targeted accumulation within specific cellular organelles offers potential for photothermal treatments or drug delivery vectors. This substrate-mediated approach provides a step change to studying nanomaterial–cellular interactions, taking advantage of the broad palette of available two-dimensional (2D) materials and making use of mechanosensing to stimulate tunable responses, with potential for therapies and diagnostics

Imaging the disc rim and a moving close-in companion candidate in the pre-transitional disc of V1247 Orionis

Context. V1247 Orionis harbours a pre-transitional disc with a partially cleared gap. Earlier interferometric and polarimetric observations revealed strong asymmetries both in the gap region and in the outer disc. The presence of a companion was inferred to explain these asymmetric structures and the ongoing disc clearing.We acknowledge support from an ERC Starting Grant (Grant Agreement No. 639889), STFC Rutherford Fellowship (ST/J004030/1), STFC Rutherford Grant (ST/K003445/1), Marie Sklodowska-Curie CIG grant (Ref. 618910) and Philip Leverhulme Prize (PLP-2013-110). We additionally acknowledge support from NASA KPDA grants (JPL-1452321, 1474717, 1485953, 1496788)

Langmuir films of layered nanomaterials: edge interactions and cell culture applications

The application of nanomaterials in technology is limited by challenges in their processing into macroscopic structures with reliable and scalable methods. Herein, it is demonstrated that using scalable fabrication methods such as liquid-phase exfoliation it is possible to produce dispersions of a wide variety of layered nanomaterials, including the first demonstration of boron nitride, with controllable and standardised size and thickness scaling. These can be used as-produced for Langmuir deposition, to create single layer films with tuneable density. Of particular importance, we show that the difference in edge chemistry of these materials dictates the film formation process, and therefore can be used to provide a generic fabrication methodology that is demonstrated for various layered nanomaterials, including graphene, boron nitride and transition metal dichalcogenides. We show that this leads to controllable cancer cell growth on graphene substrates with different edge densities but comparable surface coverage, which can be produced on a statistically relevant cell study amount. This opens up pathways for the generic fabrication of a range of layered nanomaterial films for various applications, towards a commercially viable film fabrication technology

Tuneable synthetic reduced graphene oxide scaffolds elicit high levels of three-dimensional glioblastoma interconnectivity in vitro

Three-dimensional tissue scaffolds have utilised nanomaterials to great effect over the last decade. In particular, scaffold design has evolved to consider mechanical structure, morphology, chemistry, electrical properties, and of course biocompatibility - all vital to the performance of the scaffold and how successful they are in developing cell cultures. We have developed an entirely synthetic and tuneable three-dimensional scaffold of reduced graphene oxide (rGO) that shows good biocompatibility, and favourable mechanical properties as well as reasonable electrical conductivity. Importantly, the synthesis is scaleable and suitable for producing scaffolds of any desired geometry and size, and we observe a high level of biocompatibility and cell proliferation for multiple cell lines. In particular, one of the most devastating forms of malignant brain cancer, glioblastoma (GBM), grows especially well on our rGO scaffold in vitro, and without the addition of response-specific growth factors. We have observed that our scaffold elicits spontaneous formation of a high degree of intercellular connections across the GBM culture. This phenomenon is not well documented in vitro and nothing similar has been observed in synthetic scaffolds without the use of response-specific growth factors - which risk obscuring any potential phenotypic behaviour of the cells. The use of scaffolds like ours, which are not subject to the limitations of existing two-dimensional substrate technologies, provide an excellent system for further investigation into the mechanisms behind the rapid proliferation and success of cancers like GBM. These synthetic scaffolds can advance our understanding of these malignancies in the pursuit of improved theranostics against them

Allelic heterogeneity and more detailed analyses of known loci explain additional phenotypic variation and reveal complex patterns of association

The identification of multiple signals at individual loci could explain additional phenotypic variance (‘missing heritability’) of common traits, and help identify causal genes. We examined gene expression levels as a model trait because of the large number of strong genetic effects acting in cis. Using expression profiles from 613 individuals, we performed genome-wide single nucleotide polymorphism (SNP) analyses to identify cis-expression quantitative trait loci (eQTLs), and conditional analysis to identify second signals. We examined patterns of association when accounting for multiple SNPs at a locus and when including additional SNPs from the 1000 Genomes Project. We identified 1298 cis-eQTLs at an approximate false discovery rate 0.01, of which 118 (9%) showed evidence of a second independent signal. For this subset of 118 traits, accounting for two signals resulted in an average 31% increase in phenotypic variance explained (Wilcoxon P< 0.0001). The association of SNPs with cis gene expression could increase, stay similar or decrease in significance when accounting for linkage disequilibrium with second signals at the same locus. Pairs of SNPs increasing in significance tended to have gene expression increasing alleles on opposite haplotypes, whereas pairs of SNPs decreasing in significance tended to have gene expression increasing alleles on the same haplotypes. Adding data from the 1000 Genomes Project showed that apparently independent signals could be potentially explained by a single association signal. Our results show that accounting for multiple variants at a locus will increase the variance explained in a substantial fraction of loci, but that allelic heterogeneity will be difficult to define without resequencing loci and functional work