The Arecibo Galaxy Environment Survey: II. A HI view of the Abell cluster 1367 and its outskirts

We present 21 cm HI line observations of 5x1 square degrees centered on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with SDSS optical imaging we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wavelength are also discussed.Comment: 22 pages, 15 figures, 4 tables. Accepted for publication on MNRAS Main Journal. High resolution version of this paper can be downloaded at http://www.astro.cf.ac.uk/pub/Luca.Cortese/papers/ages_a1367.pdf . Datacubes and catalogs can be downloaded at http://www.naic.edu/~ages/public_data.htm

Scaling Relations of Dwarf Galaxies without Supernova-Driven Winds

Nearby dwarf galaxies exhibit tight correlations between their global stellar and dynamical properties, such as circular velocity, mass-to-light ratio, stellar mass, surface brightness, and metallicity. Such correlations have often been attributed to gas or metal-rich outflows driven by supernova energy feedback to the interstellar medium. We use high-resolution cosmological simulations of high-redshift galaxies with and without energy feedback, as well as analytic modeling, to investigate whether the observed correlations can arise without supernova-driven outflows. We find that the simulated dwarf galaxies exhibit correlations similar to those observed as early as z~10, regardless of whether supernova feedback is included. We also show that the correlations can be well reproduced by our analytic model that accounts for realistic gas inflow but assumes no outflows, and star formation rate obeying the Kennicutt-Schmidt law with a critical density threshold. We argue that correlations in simulated galaxies arise due to the increasingly inefficient conversion of gas into stars in low-mass dwarf galaxies rather than supernova-driven outflows. We also show that the decrease of the observed effective yield in low-mass objects, often used as an indicator of gas and metal outflows, can be reasonably reproduced in our simulations without outflows. We show that this trend can arise if a significant fraction of metals in small galaxies is spread to the outer regions of the halo outside the stellar extent via mixing. In this case the effective yield can be significantly underestimated if only metals within the stellar radius are taken into account. Measurements of gas metallicity in the outskirts of gaseous disks of dwarfs would thus provide a key test of such explanation.Comment: accepted for publication in ApJ, 19 pages, 12 figures, uses emulateapj

Quantum statistical effects in nano-oscillator arrays

We have theoretically predicted the density of states(DOS), the low temperature specific heat, and Brillouin scattering spectra of a large, free standing array of coupled nano-oscillators. We have found significant gaps in the DOS of 2D elastic systems, and predict the average DOS to be nearly independent of frequency over a broad band f < 50GHz. At low temperatures, the measurements probe the quantum statistics obeyed by rigid body modes of the array and, thus, could be used to verify the quantization of the associated energy levels. These states, in turn, involve center-of mass motion of large numbers of atoms, N > 1.e14, and therefore such observations would extend the domain in which quantum mechanics has been experimentally tested. We have found the required measurement capability to carry out this investigation to be within reach of current technology.Comment: 1 tex file, 3 figures, 1 bbl fil

Anomalous quantum chaotic behavior in nanoelectromechanical structures

It is predicted that for sufficiently strong electron-phonon coupling an anomalous quantum chaotic behavior develops in certain types of suspended electro-mechanical nanostructures, here comprised by a thin cylindrical quantum dot (billiard) on a suspended rectangular dielectric plate. The deformation potential and piezoelectric interactions are considered. As a result of the electron-phonon coupling between the two systems the spectral statistics of the electro-mechanic eigenenergies exhibit an anomalous behavior. If the center of the quantum dot is located at one of the symmetry axes of the rectangular plate, the energy level distributions correspond to the Gaussian Orthogonal Ensemble (GOE), otherwise they belong to the Gaussian Unitary Ensemble (GUE), even though the system is time-reversal invariant.Comment: 4 pages, pdf forma

Omnivorousness in sport: The importance of social capital and networks

There has been for some time a significant and growing body of research around the relationship between sport and social capital. Similarly, within sociology there has been a corpus of work that has acknowledged the emergence of the omnivore–univore relationship. Surprisingly, relatively few studies examining sport and social capital have taken the omnivore–univore framework as a basis for understanding the relationship between sport and social capital. This gap in the sociology of sport literature and knowledge is rectified by this study that takes not Putnam, Coleman or Bourdieu, but Lin’s social network approach to social capital. The implications of this article are that researchers investigating sport and social capital need to understand more about how social networks and places for sport work to create social capital and, in particular, influence participating in sporting activities. The results indicate that social networks both facilitate and constrain sports participation; whilst family and friendship networks are central in active lifestyles, those who are less active have limited networks

Helenalin-mediated Post-transcriptional Regulation of p21(Cip1) Inhibits 3T3-L1 Preadipocyte Proliferation

Abstract: We have previously shown that post-transcriptional mechanisms involving the 26S proteasome regulate the cyclin-dependent kinase inhibitors (CKIs), p21(Cip1) and p27(Kip1) during preadipocyte proliferation. Earlier studies further demonstrated that the anti-inflammatory, anticarcinogenic phytochemical, helenalin is a potent inhibitor of periodic Skp2 accumulation, an Fbox protein mediating SCF E3 ligase ubiquitylation and degradation of both CKIs during S phase progression. Data presented here demonstrate that helenalin dose-dependently induced G1 arrest of synchronously replicating 3T3-L1 preadipocytes. This effect occurred in the absence of discernable indices of cell toxicity or apoptosis under the conditions used in this study. Our results demonstrate that helenalin markedly increased p21 protein accumulation in both densityarrested and proliferating preadipocytes in a dose-dependent manner. This increase in p21 protein abundance occurred without change in mRNA transcript demonstrating that posttranscriptional mechanisms were involved. This notion was further supported by the modest accumulation of polyubiquitylated p21 following treatment with helenalin suggesting that suppression of targeted p21 proteolysis by the 26S proteasome contributed to helenalin-mediated p21 accumulation. The increase in p21 protein was compartmentalized to the nucleus where p21 is known to inhibit cell cycle progression. Finally, helenalin increased protein-protein interactions between p21 and cyclin-dependent kinase 2 (Cdk2) which may account in part for the anti-proliferative effect in 3T3-L1 preadipocytes. Article: INTRODUCTION Helenalin is a naturally occurring phytochemical extracted from the aerial portion of the flowering plant, arnica montana L. Alcohol extracts containing this sesquiterpene lactone and its derivatives have been used in herbal medicine for many years to treat haematomas, sprains, rheumatic diseases, and superficial skin inflammation. Recently, helenalin has found principal use in cellular studies as a commercially available, potent inhibitor of IκB degradation and NF-κB transcriptional activity We have previously reported that p27 is regulated during S phase progression of replicating 3T3-L1 preadipocytes by post-transcriptional mechanisms involving ubiquitylation and targeted protein degradation by the 26S proteasome MATERIALS AND METHODS Materials Dulbecco&apos;s Modified Eagle&apos;s Medium (DMEM), calf bovine serum (CS), fetal bovine serum (FBS) and Trypsin-EDTA were purchased from Invitrogen. Antibodies used for immunoblotting were purchased as follows: p21 (Oncogene), Cyclin D1, α-tubulin, cleaved caspase-3, cleaved PARP, ubiquitin (Cell Signaling), GAPDH, Cyclin A (Santa Cruz), Nucleoporin p62, Cdk2, and Cdk4 (BD Biosciences). Polyclonal p21 antibody for immunoprecipitation was purchased from Santa Cruz Biotechnology. Helenalin was purchased from Biomol. Recombinant Protein-G beads for immunoprecipitation were from Pierce. Propidium Iodide and RNase A were purchased from Sigma. Polyvinylidene fluoride (PVDF) membrane was purchased from Millipore. Enhanced chemiluminescence (ECL) reagents, secondary antibodies and Nethylmaleimide (NEM) were from Pierce. Cell Culture and Induction of Differentiation Murine 3T3-L1 preadipocytes were propagated in DMEM supplemented with 10% CS until reaching density arrest at 2 days post-confluence. Cells were subsequently induced to differentiate with DMEM containing 10% FBS supplemented with 0.5mM 3-isobutyl-1-methyxanthine, 1μM dexamethasone, and 1.7μM insulin (MDI). Throughout the study, the term &quot;post-MDI&quot; refers to the time elapsed since the addition of the differentiation cocktail to the culture medium. Additionally, the term &quot;time 0&quot; refers to density-arrested, 2 days post-confluent cells immediately before the addition of MDI to the culture medium. All experiments were repeated 3-5 times to validate results and ensure reliability. Protein isolation Cells were washed with phosphate-buffered saline (PBS) and harvested in ice cold lysis buffer containing 0.1M Tris (pH 7.4), 150mM NaCl, 10% sodium dodecyl sulfate (SDS), 1% Triton X, 0.5% NP40, 1mM EDTA, 1mM EGTA, and 10mM NEM. Phosphatase inhibitors (20mM β-glycerophosphate, 10mM sodium fluoride and 2μM sodium orthovanadate) and protease inhibitors (0.3μM aprotinin, 21μM leupeptin, 1μM pepstatin, 50μM phenanthroline, 0.5uM phenylmethylsulfonyl fluoride) were freshly added to the lysis buffer immediately before use. Lysates were sonicated and centrifuged at 13,000 × g for 10 min at 4°C. Protein content was determined by bicinchoninic acid (BCA) procedures according to manufacturer&apos;s (Pierce) instructions. Immunoblotting Equal amounts of whole cell lysate protein were separated by SDS-PAGE electrophoresis. Protein samples were mixed with loading buffer containing 0.25M Tris, (pH 6.8), 4% SDS, 10% glycerol, 0.01% bromophenol blue, and 10% dithiothreitol, then heated at 80°C for 5 min prior to electrophoresis. Proteins were transferred to PVDF (Millipore), blocked in 4% milk and probed overnight at 4°C with specified primary antibodies. Membranes were subsequently probed for 1 hr at room temperature with secondary antibodies conjugated with horseradish peroxidase and results visualized with ECL using CL-XPosure film (Pierce). RNA Isolation and Analysis Total RNA was extracted from 3T3-L1 preadipocytes using the RNeasy Mini Kit according to manufacturer&apos;s (QIAGEN) instructions. Briefly, cells were lysed and homogenized using the provided QIAshredders. Column-bound RNA was DNase-treated and eluted with RNase-free water. Total RNA (1ug) from the cells was subjected to Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) using One-Step RT-PCR kit (QIAGEN).Reactions were carried out in the presence of buffer containing dNTP&apos;s (400μM), reverse transcriptase and DNA polymerase enzyme mix, and RNase inhibitor (10U). Gene specific primers designed for p21 (forward: 5&apos;-GTCTGAGCGGCCTGAAGATT&apos;3&apos; and reverse: 5&apos;-TCCTGACCCACAGCAGAAGA-3&apos;) were used at a final concentration of 0.6μM. Quantam RNA Classic II 18S primer/ competimer was used according to manufacturer&apos;s (Ambion) instruction as an internal standard in the RT-PCR reactions at a concentration of 0.6μM. RT-PCR products were electrophoresed in 1.5% agarose in the presence of ethidium bromide and analyzed on a Kodak Digital Imager. Flow Cytometry Cell cycle progression was assessed by flow cytometry as described previously Nuclear/Cytosolic Fractionation Cells were washed with PBS and incubated with ice cold isotonic buffer containing 20mM Tris, pH7.4, 125mM NaCl, 1mM EGTA, 1mM EDTA and 1mM MgCl 2 for 6 min on ice. The buffer was supplemented with fleshly prepared 0.1% NP40, and phosphatase/protease inhibitors as described above. Following detergent solubilization, cytosolic fractions were collected from the cell monolayers and clarified by centrifugation (13,000 × g for 5 min at 4°C). Intact nuclei were subsequently collected in PBS and gently pelleted by centrifugation at 300 × g for 3 min at 4°C. Nuclear proteins were extracted in ice cold buffer containing 20mM Tris (pH 7.4), 1% Triton X, 150mM NaCl, 1mM EDTA, 1mM EGTA supplemented with protease/phosphatase inhibitors and frozen at -80°C. Nuclear fraction were subsequently thawed on ice, sonicated, passed through a 21 gauge needle to shear DNA, and clarified by centrifugation at 13,000 × g for 10 min at 4°C. Immunoflourescence Cells, cultured on glass coverslips in 35mm plates, were washed with PBS, fixed with methanol free 3% Formaldehyde (Polysicences) for 20 min, permeabilized with 0.2% Triton X for 5 min, blocked for one hr with 3% BSA, and incubated overnight with primary antibody at 4°C. Coverslips were subsequently incubated with fluorescently-labeled secondary antibody, Alexa Fluor 488 anti-mouse (Molecular Probes) for 1 hr at room temperature, washed with PBS, mounted on glass slides using Antifade mounting solution (Molecular Probes) and visualized by confocal microscopy. Immunoprecipitation/Co-immunoprecipitation Cells were lysed with ice cold immunoprecipitation buffer containing 10mM Tris, 150mM NaCl, 1% TritonX, 0.5% NP-40, 1mM EDTA, 1mM EGTA and 10mM NEM as well as protease and phosphatase inhibitors as described above. Immunoprecipitations were performed using recombinant Protein G beads per manufacturer&apos;s (Pierce) instructions. Briefly, lysate (1000μg) was incubated with the appropriate antibody for 2 hrs at 4°C, mixed with beads, and incubated for an additional 2 hrs at 4°C. Immune complexes were collected by centrifugation at 2500 × g for 3 min at 4°C, washed 6 times with PBS, resuspended in loading buffer, and heated at 70°C for 3 min. Samples were centrifuged at 2500 × g for 3 min and supernatants resolved with SDS-PAGE, transferred to PVDF membranes and immunoblotted. Recombinant beads were also incubated with whole cell lysates in the absence of antibody to rule out non-specific binding of proteins to the beads. RESULTS Helenalin dose-dependently arrest preadipocytes during G1-phase of cell cycle progression independent of apoptosis Previous reports from our laboratory and others have demonstrated that density-arrested 3T3-L1 preadipocytes synchronously re-enter the cell cycle for a limited period of proliferation that precedes and is obligatory for adipocyte development Helenalin dose-dependently enhances p21 protein accumulation It is well established that cell cycle progression through the G1/S transition requires the timely decay of both p21 and p27. We have previously reported that helenalin inhibits p27 degradation through suppression of SCF E3 ligase activity responsible for polyubiquitylation targeting p27 for proteasomal degradation Helenalin induces p21 protein accumulation post-transcriptionally during density arrest and mid-G1 phase progression To determine the global mechanism linking helenalin and p21 regulation, total cell lysates and RNA were collected for comparative immunoblotting Helenalin modestly promotes the accumulation of ubiquitylated p21 To determine if helenalin increased p21 protein accumulation through posttranscriptional mechanisms involving ubiquitylation and targeted proteasomal degradation, density-arrested were treated with and without helenalin in the presence and absence of MDI for 12 hr. Cell lysates were harvested under non-denaturing conditions, immunoprecipitated with a polyclonal p21 antibody, and immunoblotted with both ubiquitin and p21 (monoclonal) antibodies. For comparative purposes, lysates were also analyzed from density-arrested cells following 6 hr exposure to the potent, specific 26S proteasome inhibitor, epoxomicin. To enhance accumulation of ubiquitin-conjugated substrates, these studies were conducted in the presence of NEM to suppress deubiquitylating enzyme activity. As illustrated in Helenalin increases p21 protein accumulation in the nucleus Subcellular protein localization is an important aspect governing p21 protein accumulation and function. To determine if helenalin leads to increased p21 compartmentalization, density-arrested cells were treated with or without helenalin either in presence or absence of MDI. Nuclear and cytosolic fractions were harvested 12 hr post-treatment and collected cell fractions were immunoblotted for p21. To confirm efficiency of fractionation, lysates were also immunoblotted for nucleoporin and α-tubulin as markers of nuclear and cytosolic fractions, respectively. As illustrated in Helenalin enhances protein interactions between p21 and Cdk2 It is well established that nuclear accumulation of p21 inhibits cell cycle progression Figure 6: Increased interaction between p21 and Cyclin D1, Cdk2, and Cdk4 following helenalin exposure (A) Density-arrested cells stimulated with and without MDI in the absence and presence of 3μM helenalin (HLN) for 12 hr were harvested, immunoprecipitated for p21 and immunoblotted for Cyclin D1, Cdk4, Cdk2 and p21. 10% input protein was immunoblotted and designated by asterisks. Helenalin does not inhibit mid-G1 accumulation of Cyclin D1 As shown above, helenalin increased protein-protein interaction between p21 and Cdk2, completely ablated the accumulation of Cyclin A known to occur during S phase progression, and increased the proportion of cells in G1 phase of the cell cycle following MDI stimulation. Each of these observations was consistent with the working model that p21 inhibition of Cdk2 activity suppressed G1/S phase transition. To further explore this premise, density-arrested cells were stimulated with and without MDI in the presence and absence of helenalin. Lysates were harvested at 12 hr post-treatment and cell cycle proteins immunoblotted as illustrated in Figure 7: Helenalin does not inhibit accumulation of Cyclin D1 at mid-G1 Total cell lysates were harvested from density-arrested 3T3-L1 preadipocytes at 0 hr and 12 hr following exposure to MDI in the absence and presence of 3μM helenalin (HLN) for 12 hr and immunoblotted as indicated. DISCUSSION Adipocyte hyperplasia, defined as the proliferation of preadipocytes and their subsequent differentiation into mature adipocytes, contributes to the development of obesity, a chronic disease that is reaching pandemic proportions in developed and developing nations Although helenalin has been shown to have anti-tumorigenic effects in cancer cells, the mechanisms by which helenalin controls cell proliferation are yet to be determined. Our study is the first to demonstrate, in any cell type, that helenalin treatment can lead to a dramatic accumulation of p21 protein. Furthermore, data presented here support a novel mechanism whereby helenalin-induced accumulation of p21 occurs through post-transcriptional processes independent of changes in mRNA transcript categorically ruling out stress-induced p53 activation and consequential changes in p21 gene expression. Data presented here demonstrate that helenalin promotes nuclear accumulation of p21 as well as modest of polyubiquitylated p21 in a manner similar to that observed following blockade of the 26S proteasome. While the precise mechanisms remains to be determined, data presented here support the premise that helenalin-mediated suppression of proteasomal activity, either direct or indirect, contributes to the dramatic accumulation of p21 in preadipocytes. We have previously reported that helenalin blocks mRNA and protein accumulation of Skp2, an F-box protein associated with the SCF E3 ligase that functions in p27 polyubiquitylation Helenalin is commercially available as a specific inhibitor of the NF-κB signaling pathway. NF-κB is a well studied transcription factor that regulates responses to inflammatory cytokines and its aberration leads to numerous chronic diseases. Helenalin inhibits the induction of NF-κB by multiple mechanisms, including alkylation of the p65 subunit which subsequently prevents DNA binding Other potential mechanisms by which helenalin could induce post-transcriptional p21 protein accumulation might involve protein-protein interactions that either restricts p21 from the nucleus where it is degraded as well as interactions that restrict p21 from proteolytic machinery within the nucleus. Selective compartmentalization is unlikely as we also demonstrate that helenalin increased nuclear, as opposed to cytosolic, p21 accumulation. Within the nucleus, others have demonstrated that p21 interaction with proliferating cell nuclear antigen (PCNA) protects p21 from proteasome-dependent degradation and promotes its protein levels Regulation of p21 protein accumulation represents a possible mechanism linking helenalin with G1 arrest. During mid-G1, p21 facilitates the assembly of Cyclin D1/Cdk4 complexes. However, under conditions of increased nuclear p21 accumulation, D-type cyclins become saturated In summary, this study provides novel data that demonstrate how a naturally occurring phytochemical, helenalin, inhibits preadipocyte proliferation. Investigation of the mechanisms responsible for G1 arrest in 3T3-L1 preadipocytes revealed that helenalin post-transcriptionally induces p21 accumulation, at least in part, by suppressing its ubiquitin-dependent and proteasome-dependent degradation. Moreover, the enhanced nuclear abundance of p21 and increased associations between p21 and Cdk2 in response to helenalin are consistent with mechanisms that suppress preadipocyte proliferation. ACKNOWLEDGMENTS We are grateful to Howard Green (Harvard Medical School) for the murine 3T3-L1 cell line

Berry effect in acoustical polarization transport in phononic crystals

We derive the semiclassical equations of motion of a transverse acoustical wave packet propagating in a phononic crystal subject to slowly varying perturbations. The formalism gives rise to Berry effect terms in the equations of motion, manifested as the Rytov polarization rotation law and the polarization-dependent Hall effect. We show that the formalism is also applicable to the case of non-periodic inhomogeneous media, yielding explicit expressions for the Berry effect terms.Comment: To appear in JETP Let

Me against who? Male guppies adjust mating behaviour according to their rival’s presence and attractiveness

This work was supported by Portuguese National Funds through FCT (Fundação para a Ciência e a Tecnologia), within the cE3c Unit FCT funding (grant number UID/BIA/00329/2013), IO PhD grant (SFRH/BD/90686/2012) and SAMV (SFRH/BPD/66042/2009 and PTDC/BIA‐ANM/0810/14) and MB (SFRH/BPD/82259/2011) Post‐Doctoral research grants. This work was also supported by the ERC (European Research Council) AdG BioTIME (250189) to AEM.Sexual selection theory suggests that males need to constantly reappraise their mating decisions to take account of the presence and the phenotypes of their rivals. Here we examine this expectation by asking: (i) If the presence of a rival influences male mating behaviour; (ii) How important is the attractiveness of the rival (absolute attractiveness) in shaping male behaviour; and (iii) How does a male's attractiveness in comparison to his rival (relative attractiveness) influence a male's mating decisions. Using the Trinidadian guppy, a species in which female mate choice (based on males’ attractive traits) plays an important role in male mating outcomes, we recorded the frequency of courtship displays and unsolicited attempts by focal males. First, we quantified focal male mating behaviour with and without a rival. Since the probability of a successful mating is, on average, halved by the presence of a rival, we predicted that under competition the focal male would invest more in less costly mating tactic—unsolicited attempts. Second, we examined how the rival's standard length and area of orange coloration mediated focal male mating behaviour. We found that rival presence influenced how focal males responded to females in terms of both mating tactics. However, the rival attractiveness elicited changes only in male courtship display. Focal males increased courtship display rate if his rival was small or if possessed large amounts of orange, regardless of considering rival absolute or relative attractiveness. Our results show that males invest in the costlier mating tactic when there is no rival or in the presence of a smaller rival. Interestingly, they make a similar investment in the presence of an attractive orange rival. Overall, this study highlights the importance of fine‐grained male decisions in mating encounters and shows that mating tactics are differentially shaped by multiple competition risk cues.PostprintPeer reviewe

The cell adhesion molecule L1 regulates the expression of choline acetyltransferase and the development of septal cholinergic neurons

Mutations in the L1 gene cause severe brain malformations and mental retardation. We investigated the potential roles of L1 in the regulation of choline acetyltransferase (ChAT) and in the development of septal cholinergic neurons, which are known to project to the hippocampus and play key roles in cognitive functions. Using stereological approaches, we detected significantly fewer ChAT-positive cholinergic neurons in the medial septum and vertical limb of the diagonal band of Broca (MS/VDB) of 2-week-old L1-deficient mice compared to wild-type littermates (1644 ± 137 vs. 2051 ± 165, P = 0.038). ChAT protein levels in the septum were 53% lower in 2-week-old L1-deficient mice compared to wild-type littermates. ChAT activity in the septum was significantly reduced in L1-deficient mice compared to wild-type littermates at 1 (34%) and 2 (40%) weeks of age. In vitro, increasing doses of L1-Fc induced ChAT activity in septal neurons with a significant linear trend (*P = 0.0065). At 4 weeks of age in the septum and at all time points investigated in the caudate-putamen (CPu), the number of ChAT-positive neurons and the levels of ChAT activity were not statistically different between L1-deficient mice and wild-type littermates. The total number of cells positive for the neuronal nuclear antigen (NeuN) in the MS/VDB and CPu was not statistically different in L1-deficient mice compared to wild-type littermates, and comparable expression of the cell cycle marker Ki67 was observed. Our results indicate that L1 is required for the timely maturation of septal cholinergic neurons and that L1 promotes the expression and activity of ChAT in septal neurons

Elastic properties of B-C-N films grown by N2-reactive sputtering from boron carbide targets

The following article appeared in Journal of Applied Physics 114.21 (2013): 213508 and may be found at http://scitation.aip.org/content/aip/journal/jap/114/21/10.1063/1.4837655Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B4C target and N2 as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.This work has been supported by Spanish MINECO under contracts MAT2009-08786 and MAT2012-37276- C03-01 as well as by the Madrid Regional Government though contract S2009/MAT-1756