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Functional block copolymer nanoparticles: toward the next generation of delivery vehicles

POLYMER CHEMISTRY 2012年第6期3卷 1618-1628页

作者： Robb, Maxwell J. Connal, Luke A. Lee, Bongjae F. Lynd, Nathaniel A. Hawker, Craig J. Univ Calif Santa Barbara Dept Mat Dept Chem & Biochem Santa Barbara CA 93106 USA King Fahd Univ Petr & Minerals Dhahran 31261 Saudi Arabia Univ Calif Santa Barbara Mat Res Lab Santa Barbara CA 93106 USA

The self-assembly of functional block copolymers (BCPs) into dispersed nanoparticles is a powerful technique for the preparation of novel delivery vehicles with precise control of morphology and architecture. Well-defined BCPs containing an alkyne-functional, biodegradable polylactide (PLA) block were synthesized and conjugated with azide-functional coumarin dyes via copper catalyzed azide alkyne cycloaddition 'click' chemistry. Self-assembled nanoparticles with internal nanophase-separated morphologies could then be accessed by carefully controlling the composition of the BCPs and release of the covalently attached model payload was shown to occur under physiological conditions via the degradation of the PLA scaffold. These results demonstrate the potential of self-assembled nanoparticles as modular delivery vehicles with multiple functionalities, nanostructures, and compartmentalized internal morphology.

关键词： Copolymers CONTROLLED MORPHOLOGY Delivery wagons Nanoparticles Click Chemistry programmable logic arrays accuracy control block copolymers functional block

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Phospholipase A₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp temperata

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APPLIED AND ENVIRONMENTAL MICROBIOLOGY 2012年第11期78卷 3816-3823页

作者： Seo, Samyeol Lee, Sunghong Hong, Yongpyo Kim, Yonggyun Andong Natl Univ Dept Bioresource Sci Andong South Korea Andong Natl Univ Dept Appl Chem Andong South Korea

The entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata suppress insect immune responses by inhibiting the catalytic activity of phospholipase A(2) (PLA(2)), which results in preventing biosynthesis of immune-mediating eicosanoids. This study identified PLA(2) inhibitors derived from culture broths of these two bacteria. Both X. nematophila and P. temperata subsp. temperata culture broths possessed significant PLA(2)-inhibitory activities. Fractionation of these bacterial metabolites in the culture broths using organic solvent and subsequent chromatography purified seven potent PLA(2) inhibitors, three of which (benzylideneacetone [BZA], proline-tyrosine [PY], and acetylated phenylalanine-glycine-valine [FGV]) were reported in a previous study. Four other compounds (indole, oxindole, cis-cyclo-PY, and p-hydroxyphenyl propionic acid) were identified and shown to significantly inhibit PLA(2). X. nematophila culture broth contained these seven compounds, while P. temperata subsp. temperata culture broth contained three compounds (BZA, acetylated FGV, and cis-cyclo-PY). BZA was detected in the largest amount among these PLA(2) compounds in both bacterial culture broths. All seven bacterial metabolites also showed significant inhibitory activities against immune responses, such as phenoloxidase activity and hemocytic nodulation;BZA was the most potent. Finally, this study characterized these seven compounds for their insecticidal activities against the diamondback moth, Plutella xylostella. Even though these compounds showed relatively low toxicities to larvae, they significantly enhanced the pathogenicity of Bacillus thuringiensis. This study reports bacterial-origin PLA(2) inhibitors, which would be applicable for developing novel insecticides.

关键词： Photorhabdus temperata entomopathogenic bacterium Immune Response Xenorhabdus nematophila programmable logic arrays broths compounds Immunity Phospholipases A

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Synthesis and water sorption of standard and end-capped polylactides: the effect of morphology

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POLYMER CHEMISTRY 2012年第3期3卷 718-726页

作者： Koo, Donghun Du, An Palmese, Giuseppe R. Cairncross, Richard A. Drexel Univ Dept Chem & Biol Engn Philadelphia PA 19104 USA

This paper investigates the relationship between morphology and water sorption in polylactide (PLA) films. Standard PLAs and palmityl initiated end-capped PLAs were synthesized with various terminating end groups such as hydroxyl, acetoxy, and palmitoyl end groups. Results from wide angle X-ray scattering and atomic force microscopy were correlated with different sorption phenomena, suggesting that crystallization and microphase separation between amorphous PLA and hydrophobic end-group-rich domains reduced water sorption in PLA. The morphological changes were affected by end-group composition, molecular weight and stereoisomerism.

关键词： programmable logic arrays synthesis END-CAPPING WIDE ANGLE X-RAY SCATTERING Polylactides stereoisomerism Microphase separation Pellicular Water

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Stereocomplex-nanocomposite formation of polylactide/fluorinated-clay with superior thermal property using supercritical fluid

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MACROMOLECULAR RESEARCH 2012年第6期20卷 545-548页

作者： Purnama, Purba Lim, Soon Ho Jung, Youngmee Kim, Soo Hyun Korea Inst Sci & Technol Biomat Res Ctr Seoul 136791 South Korea Univ Sci & Technol Taejon 305333 South Korea Korea Inst Sci & Technol Polymer Hybrid Res Ctr Seoul 136791 South Korea

Polylactides (PLA) is a well-known green polymer because of their sustainability, biocompatibility and biodegradabil-ity. They have been used in various applications. But, for specific applications, homopolymer polylactide (PLA) has limitations because of thermal and mechanical properties. As we knew, stereocomplexation and nanocomposites are the choices to enhance the properties of PLA. Stereocomplexation of PLA with different configuration can enhance the thermal properties of polylactide by generated stereocomplex polylactide (s-PLA). This macromolecule has increasing the melting point about ～50 °C higher than its homopolymer. In other hand, the addition of inorganic material into polymer generated a nano-scale dispersion of filler (inorganic material) in the polymer matrix, so-called *** exhibits superior physical mechanical properties.

关键词： Homopolymers programmable logic arrays supercritical fluids melting point Polylactides inorganic materials Mechanical properties Thermal properties

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Micromagnetic Investigation of the S-State Reconfigurable logic Element

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IEEE TRANSACTIONS ON MAGNETICS 2012年第7期48卷 2103-2111页

作者： Hu, L. Hesjedal, T. Univ Waterloo Dept Elect & Comp Engn Magnet Mat Lab Waterloo ON N2L 3G1 Canada RIM Waterloo ON N2L 3W8 Canada Univ Oxford Clarendon Lab Oxford OX1 3PU England

Magnetic nanostructures are promising for nonvolatile data storage applications, as well as for reconfigurable logic devices. The derived magnetic logic concepts are commonly relying on the magnetostatic coupling of small ensembles or larger chains and networks of nanostructures. Recently, we presented a simple single-layer logic element based on an S-shaped geometry. This reconfigurable device can be integrated with magnetoresistive elements and is relatively simple to fabricate. We present a detailed micromagnetic analysis of the geometrical parameter space in which the logic element performs reliably. The influence of imperfections on the device characteristics, that is, sidewall roughness and roundedness of the edges, is investigated. Special attention is paid to obtain configurations with symmetric input field values.

关键词： Magnetic devices magnetic domains magnetic switching micromagnetics programmable logic arrays

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Hardware Implementation of Droop Control for Isolated AC Microgrids

Hardware Implementation of Droop Control for Isolated AC Mic...

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IEEE Electrical Power and Energy Conference (EPEC)

作者： Guzman, Cristina Cardenas, Alben Agbossou, Kodjo Univ Quebec Trois Rivieres Hydrogen Res Inst Trois Rivieres PQ G9A 5H7 Canada

ISBN: (纸本)9781467320801;9781467320818

Lately the integration of Distributed generation systems privileging renewable sources for offshore regions is growing to view a reduction of air pollutant emissions. Due to the intermittency of Renewable Energy Sources (RES) it must be necessary to develop a quality advanced control of the involved power interfaces to warrant the frequency and voltage required by ac off-shore loads taking into account the absence of grid connection. The droops control is a well known control strategy used for load sharing using local information of the inverters active and reactive powers. This paper presents the experimental validation of droop control strategy, using ADAptive LInear NEuron (ADALINE) signal decomposition technique for the VSI synchronization, and within a realistic scenario representing an autonomous microgrid. The advantages of the real-time operation and parallel multi task operation have been exploited using the FPGA devices, which have been employed for the hardware implementation of each VSI (Voltage Source Inverter) control. Simulation, co-simulation and experimental results are provided to verify the validity of the proposed implementation.

关键词： Distributed power generation Droops control FPGA hardware programming power measurement programmable logic arrays artificial neural networks

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First Demonstration of logic Mapping on Nonvolatile programmable Cell Using Complementary Atom Switch

First Demonstration of Logic Mapping on Nonvolatile Programm...

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IEEE International Electron Devices Meeting (IEDM)

作者： Miyamura, M. Tada, M. Sakamoto, T. Banno, N. Okamoto, K. Iguchi, N. Hada, H. Low Power Elect Assoc & Project LEAP Tsukuba Ibaraki 3058569 Japan

ISBN: (纸本)9781467348706;9781467348720

Reconfigurable nonvolatile programmable logic using complementary atom switch (CAS) is successfully demonstrated on a 65-nm-node test chip. Various logics are realized by synthesizing RTL codes and mapping the configurations into CAS-based programmable cell array. Each cell includes the two 4-input LUTs, 19x16 crossbar switch, and 368-b CAS. The CAS integrated over CMOS reduces the cell area by 78% compared to a conventional SRAM-based design.

关键词： CMOS logic circuits programmable logic arrays switches table lookup

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The Effect of Device Parameter Variations on programmable Majority logic arrays

The Effect of Device Parameter Variations on Programmable Ma...

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IEEE Conference on Nanotechnology

作者： Harika Manem Kiran Dadhirao Garrett S. Rose Department of Electrical and Computer Engineering Polytechnic University Brooklyn NY USA

ISBN: (纸本)9781424421039

Molecular scale electronics has become an attractive alternative and even extension to existing microscale technologies as they migrate to the nanoscale. With recent research in the field of molecular and nano electronics, devices such as switches and resonant tunneling diodes (RTD) have been developed which exhibit properties such as rectification, hysteresis and negative differential resistance (NDR). These devices have been utilized to realize circuits that can implement both memory and logic structures. This work revolves around the robustness of these nanoscale devices when employed in nanoelectronic programmable majority logic arrays (PMLA), programmable logic circuits based on majority logic resulting from NDR. We also show the results of corner analysis of the circuit's performance under parameter variations, and describe the behavior requirements of the aforementioned molecular devices, especially those of molecular switches, for the system to function efficiently.

关键词： Nanoscale devices Switches programmable logic arrays Junctions Integrated circuit modeling logic arrays Heating

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Plasminogen Binding Proteins and Plasmin Generation on the Surface of Leptospira spp.: The Contribution to the Bacteria-Host Interactions

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JOURNAL OF BIOMEDICINE AND BIOTECHNOLOGY 2012年第unknown期2012卷 758513-758513页

作者： Vieira, Monica L. Atzingen, Marina V. Oliveira, Rosane Mendes, Renata S. Domingos, Renan F. Vasconcellos, Silvio A. Nascimento, Ana L. T. O. Inst Butantan Ctr Biotecnol BR-05503900 Sao Paulo Brazil Univ Sao Paulo Inst Ciencias Biomed Interunidades Biotecnol BR-05508900 Sao Paulo Brazil Univ Sao Paulo Fac Med Vet & Zootecnia Lab Zoonoses Bacterianas VPS BR-05508270 Sao Paulo Brazil

Leptospirosis is considered a neglected infectious disease of human and veterinary concern. Although extensive investigations on host-pathogen interactions have been pursued by several research groups, mechanisms of infection, invasion and persistence of pathogenic Leptospira spp. remain to be elucidated. We have reported the ability of leptospires to bind human plasminogen (PLG) and to generate enzimatically active plasmin (PLA) on the bacteria surface. PLA-coated Leptospira can degrade immobilized ECM molecules, an activity with implications in host tissue penetration. Moreover, we have identified and characterized several proteins that may act as PLG-binding receptors, each of them competent to generate active plasmin. The PLA activity associated to the outer surface of Leptospira could hamper the host immune attack by conferring the bacteria some benefit during infection. The PLA-coated leptospires obstruct complement C3b and IgG depositions on the bacterial surface, most probably through degradation. The decrease of leptospiral opsonizationmight be an important aspect of the immune evasion strategy. We believe that the presence of PLA on the leptospiral surface may (i) facilitate host tissue penetration, (ii) help the bacteria to evade the immune system and, as a consequence, (iii) permit Leptospira to reach secondary sites of infection.

关键词： Fibrinolysin Leptospiroses Complement C3b Plasminogen programmable logic arrays Infection by site bacteria Leptospira outer surface Immune Evasion Host-Pathogen Interactions

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Development of microfabricated phononic crystal resonators based on two-dimensional silicon slab

Development of microfabricated phononic crystal resonators b...

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IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS)

作者： Nan Wang Fu-Li Hsiao Moorthi Palaniapan Chengkuo Lee Department of Electrical and Computer Engineering National University of Singapore Singapore

This paper shows the design, fabrication and characterization of novel micromechanical resonators with Bloch-mode resonance by creating defects on a two-dimensional (2-D) silicon phononic crystal (PnC) slab. The PnC slab was made by etching a square array of cylindrical air holes in a 10 μm thick free-standing silicon plate, while the defects are created by replacing periodically arranged three rows of air holes with one row of air holes at the centre of the PnC region. The radius of the central air holes (r') is also varied to study the effect of r' on the performance of the PnC resonators. Piezoelectric aluminium nitride (AlN) film is employed as the inter-digital transducers (IDT) to transmit and detect acoustic waves, thus making the whole microfabrication process CMOS-compatible. We also fabricate a pure PnC structure with a stopband of 140 MHz

关键词： Resonant frequency Crystals Ultrasonic variables measurement Solids Nanoelectromechanical systems Cavity resonators programmable logic arrays

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