378 research outputs found

    Self-Assembly of Optical Molecules with Supramolecular Concepts

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    Fabrication of nano-sized objects is one of the most important issues in nanoscience and nanotechnology. Soft nanomaterials with flexible properties have been given much attention and can be obtained through bottom-up processing from functional molecules, where self-assembly based on supramolecular chemistry and designed assembly have become crucial processes and techniques. Among the various functional molecules, dyes have become important materials in certain areas of nanotechnology and their self-assembling behaviors have been actively researched. In this short review, we briefly introduce recent progress in self-assembly of optical molecules and dyes, based mainly on supramolecular concepts. The introduced examples are classified into four categories: self-assembly of (i) low-molecular-weight dyes and (ii) polymeric dyes and dye self-assembly (iii) in nanoscale architectures and (iv) at surfaces

    Hydrotalcite-Supported Ag/Pd Bimetallic Nanoclusters Catalyzed Oxidation and One-Pot Aldol Reaction in Water

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    A highly active hydrotalcite-supported Ag/Pd bimetallic nanocluster catalyst has been developed by a simple, easy and safe chemical reduction method. The catalyst was characterized by high-resolution transmission electron microscopy (HR-TEM), which revealed very small (3.2 ± 0.7 nm) nanoclusters with a narrow size distribution. The bimetallic Ag/Pd catalyst showed strong cooperation between Ag and Pd for the alcohol oxidation reaction. The developed catalyst provided an efficient and environmentally friendly method for alcohol oxidation and one-pot cross-aldol condensation in water. A broad scope of α,β-unsaturated ketones with good to excellent yields were obtained under very mild conditions. This catalytic system offers an easy preparation method with a simple recovery process, good activity and reusability of up to five cycles without significant loss in the catalytic activity

    Fabrication and characterization of branched carbon nanostructures

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    Carbon nanotubes (CNTs) have atomically smooth surfaces and tend not to form covalent bonds with composite matrix materials. Thus, it is the magnitude of the CNT/fiber interfacial strength that limits the amount of nanomechanical interlocking when using conventional CNTs to improve the structural behavior of composite materials through reinforcement. This arises from two wellknown, long standing problems in this research field: (a) inhomogeneous dispersion of the filler, which can lead to aggregation and (b) insufficient reinforcement arising from bonding interactions between the filler and the matrix. These dispersion and reinforcement issues could be addressed by using branched multiwalled carbon nanotubes (b-MWCNTs) as it is known that branched fibers can greatly enhance interfacial bonding and dispersability. Therefore, the use of b-MWCNTs would lead to improved mechanical performance and, in the case of conductive composites, improved electrical performance if the CNT filler was better dispersed and connected. This will provide major benefits to the existing commercial application of CNT-reinforced composites in electrostatic discharge materials (ESD): There would be also potential usage for energy conversion, e.g., in supercapacitors, solar cells and Li-ion batteries. However, the limited availability of b-MWCNTs has, to date, restricted their use in such technological applications. Herein, we report an inexpensive and simple method to fabricate large amounts of branched-MWCNTs, which opens the door to a multitude of possible applications

    Chelate stabilized metal oxides for visible light photocatalyzed water oxidations

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    Lactate-stabilized calcium manganese oxide and cobalt hydroxide nanoparticles were utilized as catalysts in visible light photocatalyzed water oxidations. Chelated bi-metallic catalysts captured decomposed cobalt based electron acceptor and gave prolonged two stage reactions. Hydroxylated Co–lactates gave high TOF and O2 yields. Chelation produced extended reactions, higher yields and reduced waste.</p

    Visible light promoted photocatalytic water oxidation:proton and electron collection: via a reversible redox dye mediator

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    A quinone analogue as reversible electron and proton collector in visible light promoted water oxidations was investigated. Reagents were incorporated into microporous silica with surface absorbed cobalt catalyst. Reversible storage molecules are an important step towards solar fuels.</p

    Intelligent Chiral Sensing Based on Supramolecular and Interfacial Concepts

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    Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized

    Optimizing energy costs in a zinc and lead mine

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    Boliden Tara Mines Ltd. consumed 184.7 GWh of electricity in 2014, equating to over 1% of the national demand of Ireland or approximately 35,000 homes. Ireland's industrial electricity prices, at an average of 13 c/KWh in 2014, are amongst the most expensive in Europe. Cost effective electricity procurement is ever more pressing for businesses to remain competitive. In parallel, the proliferation of intelligent devices has led to the industrial Internet of Things paradigm becoming mainstream. As more and more devices become equipped with network connectivity, smart metering is fast becoming a means of giving energy users access to a rich array of consumption data. These modern sensor networks have facilitated the development of applications to process, analyse, and react to continuous data streams in real-time. Subsequently, future procurement and consumption decisions can be informed by a highly detailed evaluation of energy usage. With these considerations in mind, this paper uses variable energy prices from Ireland’s Single Electricity Market, along with smart meter sensor data, to simulate the scheduling of an industrial-sized underground pump station in Tara Mines. The objective is to reduce the overall energy costs whilst still functioning within the system's operational constraints. An evaluation using real-world electricity prices and detailed sensor data for 2014 demonstrates significant savings of up to 10.72% over the year compared to the existing control systems

    Estimation of Enantiomeric Excess Based on Rapid Host–Guest Exchange

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    Chiral molecules possess enantiomers that have non-superimposable chemical structures but exhibit identical nuclear magnetic resonance (NMR) spectra. This feature prevents the use of NMR spectroscopic methods for the determination of enantiomeric excesses (ee) of chiral molecules, using simple mixtures of their enantiomers. Recently, however, it was reported that the addition of a symmetrical prochiral molecule (a reporter or host) into a solution of chiral analyte can lead to estimation of ee through interactions involving rapid exchange of the chiral analyte (guest) in the formed host–guest complex. This is due to the ee-dependent splitting of NMR resonances of the prochiral host molecule based on averaging the chemical shift non-equivalency caused by the presence of a chiral guest. The mechanism is not dependent on diastereomer formation, and 1:1 host–guest complexes can also show ee-dependent NMR peak splitting. Prochiral molecules capable of ee sensing using the NMR technique are now referred to as so-called prochiral solvating agents (pro-CSAs). pro-CSAs represent a family of reagents distinct from the commonly used NMR chiral derivatizing reagents (where chiral auxiliaries are used to derivatize enantiomers to diastereomers) or chiral solvating agents (where chiral auxiliaries interact in an asymmetric manner with analyte enantiomers). pro-CSA methods are unique since neither pro-CSA nor NMR contains chiral factors, making the technique neutral with respect to chirality. Here, we review our recent work on this matter involving several different nominally achiral receptor molecules whose unique guest binding properties and solution characteristics (especially with regard to NMR spectroscopy) allow for the estimation of ee in the corresponding chiral guests
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