Supplier Development Practices for Sustainability: A Multi-Stakeholder Perspective

Supplier development for sustainability is a critical element of sustainable supply chain management and requires extensive multi-stakeholder collaboration. This article establishes a conceptual four-stage framework to analyse the collaborative mechanisms of supplier development practices, and presents an exploratory, qualitative analysis to identify the major contributors of sustainable supplier development practices, such as NGOs, industrial associations, consulting firms, etc. Based on semi-structured interviews towards 63 organisations from different regions and industries, this article identifies three types of contributors: Drivers, Facilitators and Inspectors. Instead of traditional stakeholder engagement processes, these contributors actively collaborate with buying firms and suppliers to design, implement and evaluate sustainable supplier development programs. The article then provides a matrix to describe the supply chain coverage and supplier performance of supplier development practices, given the absence or positive involvement of Facilitators and Inspectors. We conclude our study by suggesting future research directions as well as discussing managerial implications

Biomimetic wet-stable fibres via wet spinning and diacid-based crosslinking of collagen triple helices

One of the limitations of electrospun collagen as bone-like fibrous structure is the potential collagen triple helix denaturation in the fibre state and the corresponding inadequate wet stability even after crosslinking. Here, we have demonstrated the feasibility of accomplishing wet-stable fibres by wet spinning and diacid-based crosslinking of collagen triple helices, whereby fibre ability to act as bone-mimicking mineralisation system has also been explored. Circular dichroism (CD) demonstrated nearly complete triple helix retention in resulting wetspun fibres, and the corresponding chemically crosslinked fibres successfully preserved their fibrous morphology following 1-week incubation in phosphate buffer solution (PBS). The presented novel diacid-based crosslinking route imparted superior tensile modulus and strength to the resulting fibres indicating that covalent functionalization of distant collagen molecules is unlikely to be accomplished by current state-of-the-art carbodiimide-based crosslinking. To mimic the constituents of natural bone extra cellular matrix (ECM), the crosslinked fibres were coated with carbonated hydroxyapatite (CHA) through biomimetic precipitation, resulting in an attractive biomaterial for guided bone regeneration (GBR), e.g. in bony defects of the maxillofacial region

Magnetism and Charge Dynamics in Iron Pnictides

In a wide variety of materials, such as copper oxides, heavy fermions, organic salts, and the recently discovered iron pnictides, superconductivity is found in close proximity to a magnetically ordered state. The character of the proximate magnetic phase is thus believed to be crucial for understanding the differences between the various families of unconventional superconductors and the mechanism of superconductivity. Unlike the AFM order in cuprates, the nature of the magnetism and of the underlying electronic state in the iron pnictide superconductors is not well understood. Neither density functional theory nor models based on atomic physics and superexchange, account for the small size of the magnetic moment. Many low energy probes such as transport, STM and ARPES measured strong anisotropy of the electronic states akin to the nematic order in a liquid crystal, but there is no consensus on its physical origin, and a three dimensional picture of electronic states and its relations to the optical conductivity in the magnetic state is lacking. Using a first principles approach, we obtained the experimentally observed magnetic moment, optical conductivity, and the anisotropy of the electronic states. The theory connects ARPES, which measures one particle electronic states, optical spectroscopy, probing the particle hole excitations of the solid and neutron scattering which measures the magnetic moment. We predict a manifestation of the anisotropy in the optical conductivity, and we show that the magnetic phase arises from the paramagnetic phase by a large gain of the Hund's rule coupling energy and a smaller loss of kinetic energy, indicating that iron pnictides represent a new class of compounds where the nature of magnetism is intermediate between the spin density wave of almost independent particles, and the antiferromagnetic state of local moments.Comment: 4+ pages with additional one-page supplementary materia

Experimental demonstration of flexible bandwidth networking with real-time impairment awareness

We demonstrate a flexible-bandwidth network testbed with a real-time, adaptive control plane that adjusts modulation format and spectrum-positioning to maintain quality of service (QoS) and high spectral efficiency. Here, low-speed supervisory channels and field-programmable gate arrays (FPGAs) enabled real-time impairment detection of high-speed flexible bandwidth channels (flexpaths). Using premeasured correlation data between the supervisory channel quality of transmission (QoT) and flexpath QoT, the control plane adapted flexpath spectral efficiency and spectral location based on link quality. Experimental demonstrations show a back-to-back link with a 360-Gb/s flexpath in which the control plane adapts to varying link optical signal to noise ratio (OSNR) by adjusting the flexpath's spectral efficiency (i.e., changing the flexpath modulation format) between binary phase-shift keying (BPSK), quaternary phase-shift keying (QPSK), and eight phase-shift keying (8PSK). This enables maintaining the data rate while using only the minimum necessary bandwidth and extending the OSNR range over which the bit error rate in the flexpath meets the quality of service (QoS) requirement (e. g. the forward error correction (FEC) limit). Further experimental demonstrations with two flexpaths show a control plane adapting to changes in OSNR on one link by changing the modulation format of the affected flexpath (220 Gb/s), and adjusting the spectral location of the other flexpath (120 Gb/s) to maintain a defragmented spectrum. (C) 2011 Optical Society of Americ

A perspective from extinct radionuclides on a Young Stellar Object: The Sun and its accretion disk

Meteorites, which are remnants of solar system formation, provide a direct glimpse into the dynamics and evolution of a young stellar object (YSO), namely our Sun. Much of our knowledge about the astrophysical context of the birth of the Sun, the chronology of planetary growth from micrometer-sized dust to terrestrial planets, and the activity of the young Sun comes from the study of extinct radionuclides such as 26Al (t1/2 = 0.717 Myr). Here we review how the signatures of extinct radionuclides (short-lived isotopes that were present when the solar system formed and that have now decayed below detection level) in planetary materials influence the current paradigm of solar system formation. Particular attention is given to tying meteorite measurements to remote astronomical observations of YSOs and modeling efforts. Some extinct radionuclides were inherited from the long-term chemical evolution of the Galaxy, others were injected into the solar system by a nearby supernova, and some were produced by particle irradiation from the T-Tauri Sun. The chronology inferred from extinct radionuclides reveals that dust agglomeration to form centimeter-sized particles in the inner part of the disk was very rapid (<50 kyr), planetesimal formation started early and spanned several million years, planetary embryos (possibly like Mars) were formed in a few million years, and terrestrial planets (like Earth) completed their growths several tens of million years after the birth of the Sun.Comment: 49 pages, 9 figures, 1 table. Uncorrected preprin

Hierarchically Assembled Type I Collagen Fibres as Biomimetic Building Blocks of Biomedical Membranes

Wet spinning is an established fibre manufacturing route to realise collagen fibres with preserved triple helix architecture and cell acceptability for applications in biomedical membranes. However, resulting fibres still need to be chemically modified post-spinning to ensure material integrity in physiological media, with inherent risks of alteration of fibre morphology and with limited opportunities to induce fibrillogenesis following collagen fixation in the crosslinked state. To overcome this challenge, we hypothesised that a photoactive type I collagen precursor bearing either single or multiple monomers could be employed to accomplish hierarchically assembled fibres with improved processability, macroscopic properties and nanoscale organisation via sequential wet spinning and UV-curing. In-house-extracted type I rat tail collagen functionalised with both 4-vinylbenzyl chloride (4VBC) and methacrylate residues generated a full hydrogel network following solubilisation in a photoactive aqueous solution and UV exposure, whereby ~85 wt.% of material was retained following 75-day hydrolytic incubation. Wide-angle X-ray diffraction confirmed the presence of typical collagen patterns, whilst an averaged compression modulus and swelling ratio of more than 290 kPa and 1500 wt.% was recorded in the UV-cured hydrogel networks. Photoactive type I collagen precursors were subsequently wet spun into fibres, displaying the typical dichroic features of collagen and regular fibre morphology. Varying tensile modulus (E = 5 ± 1 − 11 ± 4 MPa) and swelling ratio (SR = 1880 ± 200 − 3350 ± 500 wt.%) were measured following post-spinning UV curing and equilibration with phosphate-buffered saline (PBS). Most importantly, 72-h incubation of the wet spun fibres in PBS successfully induced renaturation of collagen-like fibrils, which were fixed following UV-induced network formation. The whole process proved to be well tolerated by cells, as indicated by a spread-like cell morphology following a 48-h culture of L929 mouse fibroblasts on the extracts of UV-cured fibres

Using Magentix2 in Smart-Home Environments

[EN] In this paper, we present the application of a multi-agent platform Magentix2 for the development of MAS in smart-homes. Specificallly, the use of Magentix2 (http://gti-ia.upv.es/sma/tools/magentix2/index.php) platform facilitates the management of the multiple occupancy in smart living spaces. Virtual organizations provide the possibility of defining a set of norms and roles that facilitate the regulation and control of the actions that can be carried out by the internal and external agents depending on their profile. We illustrate the applicability of our proposal with a set of scenarios. © Springer International Publishing Switzerland 2015.This work is supported by the Spanish government grants CONSOLIDER INGENIO 2010 CSD2007-00022, MINECO/FEDER TIN2012-36586-C03-01, TIN2011-27652-C03-01, and SP2014800.Valero Cubas, S.; Del Val Noguera, E.; Alemany Bordera, J.; Botti, V. (2015). Using Magentix2 in Smart-Home Environments. En 10th International Conference on Soft Computing Models in Industrial and Environmental Applications. Springer Verlag. 27-37. https://doi.org/10.1007/978-3-319-19719-7_3S2737Bajo J, Fraile JA, Pérez-Lancho B, Corchado JM (2010) The thomas architecture in home care scenarios: a case study. Expert Syst Appl 37(5):3986–3999Cetina C, Giner P, Fons J, Pelechano V (2009) Autonomic computing through reuse of variability models at runtime: The case of smart homes. Computer 42(10):37–43Cook DJ (2009) Multi-agent smart environments. J Ambient Intell Smart Environ 1(1):51–55Crandall AS, Cook DJ (2010) Using a hidden markov model for resident identification. In: 6th international conference on intelligent environments, pp 74–79. IEEECriado N, Argente E, Botti V (2013) THOMAS: an agent platform for supporting normative multi-agent systems. J Logic Comput 23(2):309–333Davidoff S, Lee MK, Zimmerman J, Dey A (2006) Socially-aware requirements for a smart home. In: Proceedings of the international symposium on intelligent, environments, pp 41–44Grupo de Tecnología Informática e Inteligencia Artificial (GTI-IA) (2015). http://www.gti-ia.upv.es/sma/tools/magentix2/archivos/Magentix2UserManualv2.1.0.pdf . Magentix2 User’s Manual v2.0Loseto G, Scioscia F, Ruta M, di Sciascio E (2012) Semantic-based smart homes: a multi-agent approach. In: 13th Workshop on objects and agents (WOA 2012), vol 892, pp 49–55Rodriguez S, Julián V, Bajo J, Carrascosa C, Botti V, Corchado JM (2011) Agent-based virtual organization architecture. Eng Appl Artif Intell 24(5):895–910Rodríguez S, Paz JFD, Villarrubia G, Zato C, Bajo J, Corchado JM (2015) Multi-agent information fusion system to manage data from a WSN in a residential home. Inf Fusion 23:43–57Such JM, Garca-Fornes A, Espinosa A, Bellver J (2012) Magentix2: a Privacy-enhancing Agent Platform. Eng Appl Artif IntellSun Q, Yu W, Kochurov N, Hao Q, Hu F (2013) A multi-agent-based intelligent sensor and actuator network design for smart house and home automation. J Sens Actuator Netw 2(3):557–588Val E, Criado N, Rebollo M, Argente E, Julian V (2009) Service-oriented framework for virtual organizations. 1:108–114Wu C-L, Liao C-F, Fu L-C (2007) Service-oriented smart-home architecture based on osgi and mobile-agent technology. IEEE Trans Syst Man Cybern Part C Appl Rev 37(2):193–205Yin J, Yang Q, Shen D, Li Z-N (2008) Activity recognition via user-trace segmentation. ACM Trans Sens Netw (TOSN) 4(4):1

Tunable magnetic exchange interactions in manganese-doped inverted core/shell ZnSe/CdSe nanocrystals

Magnetic doping of semiconductor nanostructures is actively pursued for applications in magnetic memory and spin-based electronics. Central to these efforts is a drive to control the interaction strength between carriers (electrons and holes) and the embedded magnetic atoms. In this respect, colloidal nanocrystal heterostructures provide great flexibility via growth-controlled `engineering' of electron and hole wavefunctions within individual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d exchange interaction between electron-hole excitations (excitons) and paramagnetic manganese ions using `inverted' core-shell nanocrystals composed of Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe. Magnetic circular dichroism studies reveal giant Zeeman spin splittings of the band-edge exciton that, surprisingly, are tunable in both magnitude and sign. Effective exciton g-factors are controllably tuned from -200 to +30 solely by increasing the CdSe shell thickness, demonstrating that strong quantum confinement and wavefunction engineering in heterostructured nanocrystal materials can be utilized to manipulate carrier-Mn wavefunction overlap and the sp-d exchange parameters themselves.Comment: To appear in Nature Materials; 18 pages, 4 figures + Supp. Inf

The connection between superconducting phase correlations and spin excitations in YBa2_2Cu3_3O6.6_{6.6}: A magnetic field study

One of the most striking universal properties of the high-transition-temperature (high-$T_c$) superconductors is that they are all derived from the hole-doping of their insulating antiferromagnetic (AF) parent compounds. From the outset, the intimate relationship between magnetism and superconductivity in these copper-oxides has intrigued researchers. Evidence for this link comes from neutron scattering experiments that show the unambiguous presence of short-range AF correlations (excitations) in cuprate superconductors. Even so, the role of such excitations in the pairing mechanism and superconductivity is still a subject of controversy. For YBa$_2$Cu$_3$O$_{6+x}$, where $x$ controls the hole-doping level, the most prominent feature in the magnetic excitations spectra is the ``resonance''. Here we show that for underdoped YBa$_2$Cu$_3$O$_{6.6}$, where $x$ and $T_c$ are below the optimal values, modest magnetic fields suppress the resonance significantly, much more so for fields approximately perpendicular rather than parallel to the CuO$_2$ planes. Our results indicate that the resonance measures pairing and phase coherence, suggesting that magnetism plays an important role in the superconductivity of cuprates. The persistence of a field effect above $T_c$ favors mechanisms with preformed pairs in the normal state of underdoped cuprates.Comment: 12 pages, 4 figures, Nature (in press