Bistability patterns and nonlinear switching with very high contrast ratio in a 1550 nm quantum dash semiconductor laser

We report on the experimental observation of optical bistability (OB) and nonlinear switching (NS) in a nanostructure laser; specifically a 1550 nm quantum dash Fabry-Perot laser subject to external optical injection and operated in reflection. Different shapes of optical bistability and nonlinear switching, anticlockwise and clockwise, with very high on-off contrast ratio (up to 180:1) between output states were experimentally measured. These results added to the potential of nanostructure lasers for enhanced performance offer promise for use in fast all-optical signal processing applications in optical networks. © 2012 American Institute of Physics

A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds

We have surveyed the N2H+ J=1-0, HC3N J=5-4, CCS J_N=4_3-3_2, NH3 (J, K) = (1, 1), (2, 2), (3, 3), and CH3OH J=7-6 lines toward the 55 massive clumps associated with infrared dark clouds by using the Nobeyama Radio Observatory 45 m telescope and the Atacama Submillimeter Telescope Experiment 10 m telescope. The N2H+, HC3N, and NH3 lines are detected toward most of the objects. On the other hand, the CCS emission is detected toward none of the objects. The [CCS]/[N2H+] ratios are found to be mostly lower than unity even in the Spitzer 24 micron dark objects. This suggests that most of the massive clumps are chemically more evolved than the low-mass starless cores. The CH3OH emission is detected toward 18 out of 55 objects. All the CH3OH-detected objects are associated with the Spitzer 24 micron sources, suggesting that star formation has already started in all the CH3OH-detected objects. The velocity widths of the CH3OH J_K=7_0-6_0 A+ and 7_{-1}-6_{-1} E lines are broader than those of N2H+ J=1-0. The CH3OH J_K=7_0-6_0 A+ and 7_{-1}-6_{-1} E lines tend to have broader linewidth in the MSX dark objects than in the others, the former being younger or less luminous than the latter. The origin of the broad emission is discussed in terms of the interaction between an outflow and an ambient cloud.Comment: Accepted to Ap

Synthesis of Two Tetrasaccharide Pentenyl Glycosides Related to the Pectic Rhamnogalacturonan I Polysaccharide

The synthesis of two protected tetrasaccharide pentenyl glycosides with diarabinan and digalactan branching related to the pectic polysaccharide rhamnogalacturonan I is reported. The strategy relies on the coupling of N-phenyl trifluoroacetimidate disaccharide donors to a common rhamnosyl acceptor. The resulting trisaccharide thioglycosides were finally coupled to an n-pentenyl galactoside acceptor to access the two protected branched tetrasaccharides

Weatherability and Leach Resistance of Wood Impregnated with Nano-Zinc Oxide

Southern pine specimens vacuum-treated with nano-zinc oxide (nano-ZnO) dispersions were evaluated for leach resistance and UV protection. Virtually, no leaching occurred in any of the nano-ZnO–treated specimens in a laboratory leach test, even at the highest retention of 13 kg/m3. However, specimens treated with high concentrations of nano-ZnO showed 58–65% chemical depletion after 12 months of outdoor exposure. Protection from UV damage after 12 months exposure is visibly obvious on both exposed and unexposed surfaces compared to untreated controls. Graying was markedly diminished, although checking occurred in all specimens. Nano-zinc oxide treatment at a concentration of 2.5% or greater provided substantial resistance to water absorption following 12 months of outdoor exposure compared to untreated and unweathered southern pine. We conclude that nano-zinc oxide can be utilized in new wood preservative formulations to impart resistance to leaching, water absorption and UV damage of wood

Investigation of the electrocatalytic reaction for the oxidation of alcohols through the formation of a metal organic framework (Mn-MIL-100)/polymer matrix on the surface of an Au electrode

An electrode composite containing a metal organic framework (Mn-MIL-100) was prepared by linkers including gold nanoparticles/polypyrrole and cysteine. The electrocatalytic application of this nanocomposite was evaluated via the oxidation of benzylic and aliphatic alcohols under open air conditions. Various active and inactive alcohol derivatives were successfully converted to the corresponding ketones with excellent yields. This advanced electrocatalyst proved to have remarkable stability over several recovery cycles from the reaction medium without significant change in its activity and selectivity and its regeneration potential. The active surface area of this electrocatalyst is very large due to its structural features, arising from the introduction of a metal organic framework (Mn-MIL-100) on a gold electrode, which provides more accessible surface sites, therefore boosting the electrocatalytic activity. The structure of the synthesized electrocatalyst has been characterized by FESEM, EDX, and AFM techniques. © 2023 The Royal Society of Chemistr

Grids of stellar models with rotation - III. Models from 0.8 to 120 Msun at a metallicity Z = 0.002

(shortened) We provide a grid of single star models covering a mass range from 0.8 to 120 Msun with an initial metallicity Z = 0.002 with and without rotation. We discuss the impact of a change in the metallicity by comparing the current tracks with models computed with exactly the same physical ingredients but with a metallicity Z = 0.014 (solar). We show that the width of the main-sequence (MS) band in the upper part of the Hertzsprung-Russell diagram (HRD), for luminosity above log(L/Lsun) > 5.5, is very sensitive to rotational mixing. Strong mixing significantly reduces the MS width. We confirm, but here for the first time on the whole mass range, that surface enrichments are stronger at low metallicity provided that comparisons are made for equivalent initial mass, rotation and evolutionary stage. We show that the enhancement factor due to a lowering of the metallicity (all other factors kept constant) increases when the initial mass decreases. Present models predict an upper luminosity for the red supergiants (RSG) of log (L/Lsun) around 5.5 at Z = 0.002 in agreement with the observed upper limit of RSG in the Small Magellanic Cloud. We show that models using shear diffusion coefficient calibrated to reproduce the surface enrichments observed for MS B-type stars at Z = 0.014 can also reproduce the stronger enrichments observed at low metallicity. In the framework of the present models, we discuss the factors governing the timescale of the first crossing of the Hertzsprung gap after the MS phase. We show that any process favouring a deep localisation of the H-burning shell (steep gradient at the border of the H-burning convective core, low CNO content) and/or the low opacity of the H-rich envelope favour a blue position in the HRD for the whole or at least a significant fraction of the core He-burning phase.Comment: 17 pages, 15 figures, 2 tables. Accepted for publication in Astronomy and Astrophysic

Macrobenthos assemblage in the shallow- water coast’s of the south Qeshm Island, with acoustic remote sensing technique

In this study the macrobenthose assemblage and their relationship with sediment texture was investigate by acoustic remote sensing. Macrobenthse in marine sediment plays an important role in ecosystem and any fluctuation in their communities will directly affect the abundance of fishery resources in the sea. Acoustic remote sensing techniques investigate the vast seabed in rather small time interval. This survey site covers approximately 233km2. Geophysics data was derived by single beam echo sounder and differential global positioning system. The sediment texture and macrobenthose identification was done with grab sampling. The most study area is shallow and covered with mud. Dominant benthic animals were Cirratulidae, Amphionomidae and Paraonidae from Polychaetes. The sediment types have no important and significant effect on distribution and richness. Thus, in all stations with monotone sediment texture, there is similar species composition. Because of monotone geological characteristic in seafloor, macrobenthose assemblage patterns are not affected by sediment texture and grain size

ICT-based solution approach for collaborative delivery of customised products

© 2016 Taylor & Francis. Growing interest on business collaboration motivates todays industries, especially small and medium enterprises (SMEs) to establish and manage dynamic and non-hierarchical business networks to respond to market opportunities with added business benefits. This business environment requires concurrent work and real-time information sharing between key business partners in order to design and develop customised products. The use of traditional communication media such as e-mail, phone and fax is not satisfactory to get real-time information and is time-consuming and most often ineffective. In such environments, an Information and Communication Technology (ICT)/Web-based technology supports real-time information sharing among networked SMEs for the collaborative design and manufacturing of customised products. This study proposes an innovative ICT platform supporting SMEs collaboration, through Web and the Internet of Things technologies, which follows the Net-Challenge conceptual approach and methodological guidelines for SMEs to form and operate virtual organisations for the collaborative development and delivery of customised products. The ICT Platform was assessed in three different industry domains, namely the textile and apparel, the footwear and the machine tools, respectively. This ICT solution promotes collaboration, with substantial advantages for SMEs including the reduction of costs and delivery time and improvement of the innovation potential