Stable Hybrid System Research Articles

Novel hybrid xerogel with CaF2: Tb3+ nanoparticles covalently embedded into silicon-oxygen network through sol-gel process

In this work, Tb3+ doped CaF2 (CaF2: Tb3+) nanoparticles were synthesized with the silylant agent synthesized from meta-aminobenzoic acid and 3-isocyanatopropyltriethoxysilane as the surface modifier. The as-synthesized nanoparticles were covalently bonded to the silicon-oxygen network through a sol-gel process with tetraethyl orthosilicate (TEOS) as the precursor, resulting in the chemically bonded hybrid xerogel. The chemical doping makes the nanoparticles evenly dispersed in the stable hybrid system. The combined techniques SEM and EDX have confirmed the hybrid xerogel formed Si–O–Si network structure and the nanoparticles were successfully embedded into the Si–O–Si network. The efficient energy transfers from silylant agent to Tb3+ ions were observed in both the nanoparticles and hybrid xerogel, showing an obvious characteristic emission of Tb3+ ions. Both decay curves of nanoparticles and the hybrid xerogel were fitted as a double exponential decay, and the hybrid xerogel exhibited longer luminescent lifetime.

Azaporphyrins Embedded on Carbon-Based Nanomaterials for Potential Use in Electrochemical Sensing-A Review.

Phthalocyanines and porphyrazines as macrocyclic aza-analogues of well-known porphyrins were deposited on diverse carbon-based nanomaterials and investigated as sensing devices. The extended π-conjugated electron system of these macrocycles influences their ability to create stable hybrid systems with graphene or carbon nanotubes commonly based on π–π stacking interactions. During a 15-year period, the electrodes modified by deposition of these systems have been applied for the determination of diverse analytes, such as food pollutants, heavy metals, catecholamines, thiols, glucose, peroxides, some active pharmaceutical ingredients, and poisonous gases. These procedures have also taken place, on occasion, in the presence of various polymers, ionic liquids, and other moieties. In the review, studies are presented that were performed for sensing purposes, involving azaporphyrins embedded on graphene, graphene oxide or carbon nanotubes (both single and multi-walled ones). Moreover, possible methods of electrode fabrication, limits of detection of each analyte, as well as examples of macrocyclic compounds applied as sensing materials, are critically discussed.

Development of MADB of P‐I controller using LMI technique in a renewable energy based AGC system and study its application in a deregulated environment including energy storage device

AbstractIn recent decades, inclusion of renewable resources is considered as one of the most promising options for the long run uninterrupted power supply without depending on conventional resources. Thus, the renewable energy generation will get more attention and massive growing, so that the goal of 40% share of electricity in the worldwide energy portfolio in 2050 would be realized. But during replacement of renewable energy by conventional energy, engineers are facing a lot of problem due to solar generation, wind generation change their characteristic rapidly with weather condition, which may cause large synchronizing imbalance between different units and generate large system delay or communication delay in large interconnected grid. In this article, the authors propose linear matrix inequalities techniques to developed margin of allowable delay for delay dependent stable hybrid system. Initially, to judge the efficacy of proposed chaotic atomic search optimization (CASO) algorithm over other evolutionary algorithms with PID controller, a thermal‐hydro gas system is considered. The second part of this article is motivated by the fact that proposed CASO algorithm with P‐I controller is superior in contrast to bacterial foraging algorithm technique. In addition to this, some energy storage devices such as fuel cell, aqua electrolyzer, and ultra‐capacitor are used to achieve a better dynamic response within specified delay margin. Moreover, to study the impact of communication delays (delay margin) due to the loss of synchronism between solar‐wind (for their unpredicted environmental features) and thermal unit (nonlinearities like generation rate constraints, boiler dynamics, and governor with the dead band) are considered in thermal unit and the simulation results verify with the effectiveness of the proposed approach on providing a balance between the delay margin and the damping performances is evaluated under deregulated environment. The simulation results help to make an inter‐relation between the delay margin and the controller gain (P‐I) which help the system operator in designing controllers gain for stable operation of the proposed hybrid system.

Block Copolymer Nanosystems Encapsulating Magnetic Nanoparticles and Drug.

The goal of this study was to investigate the solution behavior of nanosystems composed of self-assembling amphiphilic diblock copolymers, poly(ethylene oxide-b-phenyl oxazoline) and poly(isoprene-b-ethylene oxide) (PEO-b-PPhOx and PI-b-PEO), with encapsulated iron oxide nanoparticles (γ-Fe₂O₃). The hybrid nanosystems were tested in aqueous solution, under physiological conditions and in mixtures with serum proteins. Light scattering methods were used to probe changes in size and mass of the formed aggregates in different solution conditions and as a function of storage time. The developed stable hybrid systems with encapsulated magnetic nanoparticles were able to entrap the anti-inflammatory drug, indomethacin. This work demonstrates versatile nanosystems with metal oxide characteristics for bio-imaging and the potential for drug delivery in aqueous media.

Strategies to address the conservation threats posed by hybridization and genetic introgression

Hybridization poses a complex problem for biodiversity conservation but there has been little discussion of strategies and guidelines designed to address it from a management perspective. In this article I review management approaches aimed at addressing hybridization while highlighting outstanding needs. Despite real-world efforts to manage systems in which hybridization is a concern, there has been little effort to develop broadly applicable guidelines or best management practices. Management programs would be enhanced by the characterization of the patterns and processes of hybridization in nature and integrating those into planning and policy. Doing so facilitates the development of holistic strategies that balance the importance of hybridization in many biological systems while addressing situations in which human-facilitated gene flow causes concern. The shift from reactive management to emphasizing measures designed to prevent hybridization from becoming a threat has been a positive development. Examples include assessing the genetic characteristics of populations used in translocation programs. Overlooked, however, has been the management of stable hybrid systems in which the goal is not necessarily preventing intermixing but protecting stabilizing mechanisms through policy and land use management. When hybridization emerges as a legitimate threat, activities such as culling, spatial isolation, targeted harvest, and de-introgression can protect threatened genomic units. Further experimentation of these techniques and collaboration among scientists and managers will provide lessons for establishing general guidelines for the conservation community. I hope this review stimulates discussion about approaches useful for addressing hybridization and promotes further development of new techniques and frameworks.

Selective Wrapping and Supramolecular Structures of Polyfluorene–Carbon Nanotube Hybrids

We report on the photophysical properties of single-walled carbon nanotube (SWNT) suspensions in toluene solutions of poly[9,9-dioctylfluorenyl-2,7-diyl](PFO). Steady-state and time-resolved photoluminescence spectroscopy in the near-infrared and visible spectral regions are used to study the interaction of the dispersed SWNTs with the wrapped polymer. Molecular dynamics simulations of the PFO-SWNT hybrids in toluene were carried out to evaluate the energetics of different wrapping geometries. The simulated fluorescence spectra in the visible region were obtained by the quantum chemical ZINDO-CI method, using a sampling of structures obtained from the dynamics trajectories. The tested schemes consider polymer chains aligned along the nanotube axis, where chirality has a minimal effect, or forming helical structures, where a preference for high chiral angles is evidenced. Moreover, toluene affects the polymer structure favoring the helical conformation. Simulations show that the most stable hybrid system is the PFO-wrapped (8,6) nanotube, in agreement with the experimentally observed selectivity.

마이크로그리드에서 하이브리드 시스템의 Feeder Flow Mode 운영을 위한 제어 알고리즘

Active power control scheme for distributed generation in microgrid consists of feeder flow control and unit power control. Feeder flow control is more useful than the unit power control for demand-side management, because microgrid can be treated as a dispatchable load at the point of common coupling(PCC). This paper presents detailed descriptions of the feeder flow control scheme for the hybrid system in microgrid. It is divided into three parts, namely, the setting of feeder flow reference range for stable hybrid system operation, feeder flow control algorithm depending on load change in microgrid and hysteresis control. Simulation results using the PSCAD/EMTDC are presented to validate the inverter control method for a feeder flow control mode. As a result, the feeder flow control algorithm for the hybrid system in microgrid is efficient for supplying continuously active power to customers without interruption.

Chemically bonded metallic (Eu, Tb, Zn) hybrid materials through sulfide linkage: Molecular construction, physical characterization and photophysical properties

In this paper, a kind of aromatic carboxylic acid of sulfhydryl group (2-mercaptonicotinic acid) is modified with four silane crosslinking reagents (3-methacryloyloxypropyltrimethoxysilane (S 1), 3-glycidoxypropyltrimethoxysilane (S 2), 3-aminopropyltrimethoxysilane (S 3), and 3-(triethoxysilyl)propylisocyanate (S 4)) to achieve four new kinds of functionalized molecular bridge (P i ( i = 1–4)). Subsequently, four molecular bridges and lanthanides (europium and terbium) or zinc ions have been assembled via chemical bonds through a sol–gel (cohydrolysis and copolycondensation) process with inorganic precursor (tetraethoxysilane, TEOS), resulting in four novel series of chemically bonded hybrid materials which named as Ln (Zn)–M i ( i = 1–4). The coordinated bonding makes metal ions evenly dispersed in a stable hybrid system. The intramolecular energy transfer process between lanthanide ions and the molecular bridges take place within these molecular-based hybrids and especially the luminescent quantum efficiency of them are determined, suggesting that the hybrid material systems derived from different molecular bridges present different luminescence efficiencies.

Interaction of Iron Tetrasulfophthalocyanine with TiO2 Nanoparticles by XPS

Mesoporous iron tetrasulfophthalocyanine/TiO2 nanoparticles were prepared by a one-pot hydrolytic process starting from modified titanium alkoxide. The material has been characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction powder (XDR), transmission electronic microscopy (TEM), nitrogen absorption-desorption isotherm (BET), diffuse reflectance UV-visible spectrocopy and x-ray photoelectron spectroscopy (XPS). It contains anatase as the main crystalline phase (85%) along with brookite. Average crystallites size gave around 10 and 12 nm, for anatase and brookite, respectively. Diffuse reflectance UV-visible spectroscopy confirmed the presence of intact iron tetrasulfophtahlocyanine (FePcS), predominantly in dimeric form. The chemical interaction of the FePcS with the TiO2 nanoparticles was studied by using FTIR and XPS techniques which indicated that FePcS is covalently bonded onto TiO2 nanoparticles, leading to a stable hybrid system. Careful attention to binding energies of O 1s and S 2p elements in the nanohybrid material and in FePcS complex helps to shed light on this point.

Supramolecular Assembly of Hexagonal Mesostructured Germanium Sulfide and Selenide Nanocomposites Incorporating the Biologically Relevant Fe(4)S(4) Cluster Financial support from the National Science Foundation (CHE 99-03706, Chemistry Research Group) is gratefully acknowledged. Part of this work was carried out using the facilities of the Center for Electron Optics of Michigan State University.

Stable hybrid systems are generated by the reaction of adamantane [Ge4Q10]4− (Q=S, Se) clusters with substitutionally labile [Fe4S4Cl4]2− clusters templated by cationic surfactant molecules. The resulting novel hexagonal mesophases have parallel pore tunnels (see schematic representation) with separations of ≈35 Å, which may find applications in shape-selective electro- and photocatalysis, artificial photosynthesis, and biosensors.