Multicore Structures Research Articles

Mode-resolved gain analysis and lasing in multi-supermode multi-core fiber laser.

Multi-core fibers (MCFs) with coupled-cores are attractive large-mode area (LMA) specialty fiber designs that support the propagation of a few transverse modes often called supermodes (SMs). Compared to other LMA fibers, the uniqueness of MCF arises from the higher degrees of design space offered by a multitude of core-array geometries, resulting in extended flexibility to tailor SM properties. To date, the use of MCF as gain media has focused on lasers that operate in only one selected SM, typically the lowest order in-phase SM, which considerably limited the potential of these multi-core structures. Here, we expand the potential of MCF lasers by investigating multi-SM amplification and lasing schemes. Amplifier and laser systems using a 7 coupled-cores Yb-doped MCF as gain medium were successfully designed and assembled. Individual SM could be decomposed using the correlation filter technique mode analysis and the modal amplification factors (γi) were recorded. With access to amplification characteristics of individual transverse modes, a monolithic MCF laser was demonstrated that operates simultaneously on the two SMs carrying the highest optical gain.

Facile preparation of PLGA microspheres with diverse internal structures by modified double‐emulsion method for controlled release

Poly(l‐lactide‐co‐glycolide) (PLGA) microspheres with diverse internal structures and different release behaviors were prepared via a modified double‐emulsion method by introduction of heparin or carboxymethyl chitosan in the inner aqueous phase and calcium chloride in the outer aqueous phase, respectively. The main factors affecting the microsphere morphology were systematically studied, including compositions in the inner aqueous phase, the oily phase, and the outer aqueous phase. The transmission electron microscope images demonstrated that the microspheres are featured with single core, hollow, and multicore structures when their sizes were less than 200 nm, in the range of 200–700 nm, and greater than 700 nm, respectively. In comparison with hollow PLGA microspheres, the PLGA microspheres with heparin and carboxymethyl chitosan in the inner aqueous phase also showed multicore and single core structures, respectively, and exhibited higher loading efficiencies and slower release rates by using bovine serum albumin as a model for bioactive substances. It was concluded that this study provided a facile method to prepare microspheres with single core, multicore, or hollow feature, and the tunability of the different internal structures and related release profiles enables these systems cater to specific requirements for potential applications in controlled biomolecule delivery for tissue regeneration. POLYM. ENG. SCI., 55:896–906, 2015. © 2014 Society of Plastics Engineers

Enhancing the accuracy of automatic eddy detection and the capability of recognizing the multi-core structures from maps of sea level anomaly

Abstract. Automated methods are important for automatically detecting mesoscale eddies in large volumes of altimeter data. While many algorithms have been proposed in the past, this paper presents a new method, called hybrid detection (HD), to enhance the eddy detection accuracy and the capability of recognizing eddy multi-core structures from maps of sea level anomaly (SLA). The HD method has integrated the criteria of the Okubo–Weiss (OW) method and the sea surface height-based (SSH-based) method, two commonly used eddy detection algorithms. Evaluation of the detection accuracy shows that the successful detection rate of HD is ~ 96.6% and the excessive detection rate is ~ 14.2%, which outperforms the OW and those methods using SLA extrema to identify eddies. The capability of recognizing multi-core structures and its significance in tracking eddy splitting or merging events have been illustrated by comparing with the detection results of different algorithms and observations in previous literature.

Cooperative Organization in Iron Oxide Multi-Core Nanoparticles Potentiates Their Efficiency as Heating Mediators and MRI Contrast Agents

In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T(1) and T(2) contrast effect. Multi-core nanoparticles composed of maghemite cores were synthesized through a polyol approach, and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles to multi-core magnetically cooperative 30 nm nanoparticles. Three-dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving a superparamagnetic-like behavior of the multi-core structures and potentiating thermal losses. Exchange coupling in the multi-core nanoparticles modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long-term MRI detection of tumor cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and nontoxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core nanoparticles can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.

Determination of Structural Building Blocks in Heavy Petroleum Systems by Collision-Induced Dissociation Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Collision-induced dissociation Fourier Transform ion cyclotron resonance mass spectrometry (CID-FTICR MS) was developed to determine structural building blocks in heavy petroleum systems. Model compounds with both single core and multicore configurations were synthesized to study the fragmentation pattern and response factors in the CID reactions. Dealkylation is found to be the most prevalent reaction pathway in the CID. Single core molecules exhibit primarily molecular weight reduction with no change in the total unsaturation of the molecule (or Z-number as in chemical formula C(c)H(2c+Z)N(n)S(s)O(o)VNi). On the other hand, molecules containing more than one aromatic core will decompose into the constituting single cores and consequently exhibit both molecular weight reduction and change in Z-numbers. Biaryl linkage, C(1) linkage, and aromatic sulfide linkage cannot be broken down by CID with lab collision energy up to 50 eV while C(2)+ alkyl linkages can be easily broken. Naphthenic ring-openings were observed in CID, leading to formation of olefinic structures. Heavy petroleum systems, such as vacuum resid (VR) fractions, were characterized by the CID technology. Both single-core and multicore structures were found in VR. The latter is more prevalent in higher aromatic ring classes.

Organization of poly(2-ethyl-2-oxazoline)-block-poly(2-phenyl-2-oxazoline) copolymers in water solution

Diblock copolymers were prepared from 2-ethyl-2-oxazoline and 2-phenyl-2-oxazoline via living cationic polymerization using sequential addition of the monomers. Copolymer assemblies in aqueous solutions and on surface were studied with respect to changes in the hydrophilic-hydrophobic balance induced by increasing the length of the hydrophobic poly(2-phenyl-2-oxazoline) segment while the hydrophilic poly(2-ethyl-2-oxazoline) chain was kept constant with an average of 60 monomer units. The copolymer with a short segment of four 2-phenyl-2-oxazoline units assembled into highly hydrated aggregates that decreased twice in size after drying. Their structure was destroyed and network morphologies were formed upon spin-coating. The increase of the length of the hydrophobic segment resulted in aggregates that dissociated to micelle-sized particles when subjected to mechanical shear by spin-coating or filtering. These observations imply that the aggregates are multi-core structures originating from the assembly of primarily formed micelles. The copolymer self-assembly was evidenced by a combination of techniques: DLS, SLS, AFM and SEM.

Algorithms for Optimally Arranging Multicore Memory Structures

As more processing cores are added to embedded systems processors, the relationships between cores and memories have more influence on the energy consumption of the processor. In this paper, we conduct fundamental research to explore the effects of memory sharing on energy in a multicore processor. We study the Memory Arrangement (MA) Problem. We prove that the general case of MA is NP-complete. We present an optimal algorithm for solving linear MA and optimal and heuristic algorithms for solving rectangular MA. On average, we can produce arrangements that consume 49% less energy than an all shared memory arrangement and 14% less energy than an all private memory arrangement for randomly generated instances. For DSP benchmarks, we can produce arrangements that, on average, consume 20&% less energy than an all shared memory arrangement and 27% less energy than an all private memory arrangement.

The Biggest Need: a New Model of Computation

The development of HPC systems capable of exascale performance will demand innovations in hardware architecture and system software as well as programming models and methods. The combination of a vast increase in scale of such systems combined with the emergence of heterogeneous multicore structures is forcing future systems to be organized and operate on principles very different from the conventional practices of the last two decades. The biggest need for achieving exascale computing is the development of a new model of computation that will provide the new paradigm exploiting the opportunities and addressing the challenges of the emerging technologies and advanced architectures that together will comprise future exascale systems. This brief paper discusses the need for a new model of computation and the properties such a model should embody.

Multi-core structure of the Kuroshio in the East China Sea from long-term transect observations

Long-term hydrographic temperature and salinity transect data in the East China Sea from June 1955 to November 2001 are analyzed in order to examine the geostrophic velocity and the structure of the Kuroshio current. The structure of the Kuroshio Current is divided into three basic forms, a single-core structure, a double-core structure and a multi-core structure; the appearance percentage of the three forms are 53.1%, 31.4%, and 15.4%, respectively. The analysis suggests that multi-core structures have significant seasonal and interannual variabilities that are not fully understood but may relate to variations in transport and associated flow instabilities. The Kuroshio's spatial character is also analyzed in detail by applying a simplified model of motion instability into this multi-core structure of the East China Sea Kuroshio. The theoretical results are found to be consistent with the observations, suggesting that the instability of the Kuroshio in the East China Sea may bring forth the formation of the observed multi-core structure.

Multi-core cable-like TiO2 nanofibrous membranes for dye-sensitized solar cells

Multi-core cable-like TiO2 nanofibres were fabricated by calcination of composite polyvinyl acetate (PVAc)/titaniananofibres with a hot pressing pre-treatment. This resultant novel fibre structure was composedof sheaths of 200 nm in diameter and 25 nm in wall thickness, and cores filled with 24 nm thickTiO2 fibrils. The formation of multi-core cable-like structures of fibres isconsidered to be due to the enhanced phase separation of PVAc-rich andTiO2-richphases during the hot pressing process. The BET results showed that the specific surface area of pressedTiO2 membranes was much higher than that of unpressedTiO2 membranes. In this study, the novel multi-core cable-likeTiO2 fibrous membranes were used as electrode materials for dye-sensitized solar cells (DSSCs).It was observed that the photocurrent and conversion efficiency of the electrodes increasedconcurrently with increasing applied pressure and average membrane thickness in the range of1–9 µm. The maximum short circuit photocurrent and energy conversion efficiency were16.09 mA cm−2 and 5.77% when the membrane had an average thickness of9.21 µm and 8 MPa applied pressure.

Fabrication of multi-core structures in an optical fiber using plasma self-channeling

Fabrication of multi-core structures in an optical multimode fiber was first demonstrated by the scanning of plasma self-channeling excited by a femtosecond (110 fs) laser (lambdap=790 nm).

Type III glycogenosis with multicore structures

A case of an infantile type III glycogenosis (Forbes disease), confirmed by morphologic and biochemical studies, had light-microscopic, histochemical, and electron-microscopic evidence of multicore structures and type 1 fiber predominance with hypotrophy. This association is discussed with relation to the unusual clinical findings. The authors conclude that two distinct disease entities--Forbes disease and multicore myopathy--may coexist.