WorldWideScience

Sample records for attack synthetic polymers

  1. Biopolymers Versus Synthetic Polymers

    OpenAIRE

    Florentina Adriana Cziple; António J. Velez Marques

    2008-01-01

    This paper present an overview of important synthetic and natural polymers with emphasis on polymer structure, the chemistry of polymer formation. an introduction to polymer characterization. The biodegradation process can take place aerobically and anaerobically with or without the presence of light. These factors allow for biodegradation even in landfill conditions which are normally inconducive to any degradation. The sheeting used to make these packages differs...

  2. Biopolymers Versus Synthetic Polymers

    Directory of Open Access Journals (Sweden)

    Florentina Adriana Cziple

    2008-10-01

    Full Text Available This paper present an overview of important synthetic and natural polymers with emphasis on polymer structure, the chemistry of polymer formation. an introduction to polymer characterization. The biodegradation process can take place aerobically and anaerobically with or without the presence of light. These factors allow for biodegradation even in landfill conditions which are normally inconducive to any degradation. The sheeting used to make these packages differs significantly from other “degradable plastics” in the market as it does not attempt to replace the current popular materials but instead enhances them by rendering them biodegradable.

  3. Cell microencapsulation with synthetic polymers.

    Science.gov (United States)

    Olabisi, Ronke M

    2015-02-01

    The encapsulation of cells into polymeric microspheres or microcapsules has permitted the transplantation of cells into human and animal subjects without the need for immunosuppressants. Cell-based therapies use donor cells to provide sustained release of a therapeutic product, such as insulin, and have shown promise in treating a variety of diseases. Immunoisolation of these cells via microencapsulation is a hotly investigated field, and the preferred material of choice has been alginate, a natural polymer derived from seaweed due to its gelling conditions. Although many natural polymers tend to gel in conditions favorable to mammalian cell encapsulation, there remain challenges such as batch to batch variability and residual components from the original source that can lead to an immune response when implanted into a recipient. Synthetic materials have the potential to avoid these issues; however, historically they have required harsh polymerization conditions that are not favorable to mammalian cells. As research into microencapsulation grows, more investigators are exploring methods to microencapsulate cells into synthetic polymers. This review describes a variety of synthetic polymers used to microencapsulate cells. © 2014 The Authors. Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc.

  4. Polymer dynamics from synthetic polymers to proteins

    Indian Academy of Sciences (India)

    Starting from the standard model of polymer motion - the Rouse model - we briefly present some key experimental results on the mesoscopic dynamics of polymer systems. We touch the role of topological confinement as expressed in the reptation model and discuss in some more detail processes limiting the confinement.

  5. Polymer dynamics from synthetic polymers to proteins

    Indian Academy of Sciences (India)

    tures of polymer melt rheology. Large-scale protein motions on the other hand are critical for proteins to coordi- nate precise biological functions. Structural studies have documented the confor- mational flexibility in proteins accompanying their activity. Results from macro- scopic studies such as biochemical kinetics and ...

  6. Relative toxicity of pyrolysis products of some synthetic polymers

    Science.gov (United States)

    Hilado, C. J.; Slattengren, C. L.; Furst, A.; Kourtides, D. A.; Parker, J. A.

    1976-01-01

    Nineteen samples of synthetic polymers were evaluated for relative toxicity in the course of characterizing materials intended for aircraft interior applications. The generic polymers included ABS, chlorinated PVC, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryl sulfone, polyether sulfone, polybismaleimide, and polyvinyl fluoride. Test results are presented, and compared in relative rankings with similar results on cellulosic materials and other synthetic polymers. Under these test conditions, the samples of synthetic polymers were either comparable to or significantly less toxic than the samples of commercial cellulosic materials.

  7. Advances in synthetic optically active condensation polymers - A review

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available The study of optically active polymers is a very active research field, and these materials have exhibited a number of interesting properties. Much of the attention in chiral polymers results from the potential of these materials for several specialized utilizations that are chiral matrices for asymmetric synthesis, chiral stationary phases for the separation of racemic mixtures, synthetic molecular receptors and chiral liquid crystals for ferroelectric and nonlinear optical applications. Recently, highly efficient methodologies and catalysts have been developed to synthesize various kinds of optically active compounds. Some of them can be applied to chiral polymer synthesis. In a few synthetic approaches for optically active polymers, chiral monomer polymerization has essential advantages in applicability of monomer, apart from both asymmetric polymerization of achiral or prochiral monomers and enantioselective polymerization of a racemic monomer mixture. The following are the up to date successful approaches to the chiral synthetic polymers by condensation polymerization reaction of chiral monomers.

  8. Comparing the effect of bioflocculant with synthetic polymers on ...

    African Journals Online (AJOL)

    This study was aimed at introducing a novel bioflocculant to enhance anaerobic granulation in a UASB reactor for lowstrength synthetic wastewater and comparing the effect with synthetic polymers. A laboratory-scale study was undertaken to achieve this goal. Four identical UASB reactors were operated in parallel in the ...

  9. Applications of biopolymers and synthetic polymers blends: literature review

    Directory of Open Access Journals (Sweden)

    Lady Joana Rodríguez Sepúlveda

    2016-08-01

    Full Text Available Biopolymers are biodegradable commonly, fragile, hydrophilic and have low thermal resistance, which has limited its commercial application. In contrast, synthetic polymers or derived from non-renewable resources generally lower cost and limited or minimal biodegradability, have good mechanical and thermal characteristics. The blend of biopolymers and synthetic polymers provides materials with properties and reasonable costs for certain applications. This article is a literature review on the main applications recently reported for the most important blends of biopolymers and biodegradable synthetic polymers. The literature search was performed with the "Tree of Science" tool and narratively. The results showed that mixtures of aliphatic and polysaccharide polymers are the most used in engineering applications biological tissues, control drug delivery and packaging industry.

  10. High-density polymer microarrays: identifying synthetic polymers that control human embryonic stem cell growth.

    Science.gov (United States)

    Hansen, Anne; Mjoseng, Heidi K; Zhang, Rong; Kalloudis, Michail; Koutsos, Vasileios; de Sousa, Paul A; Bradley, Mark

    2014-06-01

    The fabrication of high-density polymer microarray is described, allowing the simultaneous and efficient evaluation of more than 7000 different polymers in a single-cellular-based screen. These high-density polymer arrays are applied in the search for synthetic substrates for hESCs culture. Up-scaling of the identified hit polymers enables long-term cellular cultivation and promoted successful stem-cell maintenance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Molecular weight characterisation of synthetic polymers

    CERN Document Server

    Holding, Steve R

    1995-01-01

    The report comprises a state-of-the-art overview of the subject of molecular weight characterisation, supported by an extensive, indexed bibliography. The bibliography contains over 400 references and abstracts, compiled from the Polymer Library.

  12. Controlled polymer synthesis--from biomimicry towards synthetic biology.

    Science.gov (United States)

    Pasparakis, George; Krasnogor, Natalio; Cronin, Leroy; Davis, Benjamin G; Alexander, Cameron

    2010-01-01

    The controlled assembly of synthetic polymer structures is now possible with an unprecedented range of functional groups and molecular architectures. In this critical review we consider how the ability to create artificial materials over lengthscales ranging from a few nm to several microns is generating systems that not only begin to mimic those in nature but also may lead to exciting applications in synthetic biology (139 references).

  13. Solid state NMR of biopolymers and synthetic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Jelinski, Lynn W. [Cornell Univ., Geneva, NY (United States)

    1995-12-31

    Solid state NMR has been invaluable in evaluating the structure, phase separation, and dynamics of polymers. Because polymers are generally used in the solid state, solid state NMR is especially powerful because it provides information about the materials in their native state. This review gives a general overview of solid state NMR, concentrating on solid state {sup 13} C and {sup 2} H NMR. It then focuses on two examples: the biopolymer spider silka and the engineering material polyurethane. It illustrates how solid state NMR can provide new information about synthetic and bio-polymers. (author) 11 refs., 5 figs., 3 tabs.

  14. Hydroxyapatite-reinforced polymer biocomposites for synthetic bone substitutes

    Science.gov (United States)

    Roeder, Ryan K.; Converse, Gabriel L.; Kane, Robert J.; Yue, Weimin

    2008-03-01

    Hydroxyapatite (HA)-reinforced polymer biocomposites offer a robust system to engineer synthetic bone substitutes with tailored mechanical, biological, and surgical functions. The basic design rationale has been to reinforce a tough, biocompatible polymer matrix with a bioactive HA filler. A large number of studies have investigated modifications to the biocomposite structure and composition, aimed at improving the mechanical properties, often through modified or novel processing methods. In this article, the effects of the polymer composition and molecular orientation; the HA/polymer interface; and the HA-reinforcement content, morphology, preferred orientation, and size are reviewed with respect to mechanical properties, drawing frequent comparisons between various HA-reinforced polymer composites and bone tissue.

  15. Co-pyrolysis of wood biomass and synthetic polymers mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, V.I.; Beregovtsova, N.G.; Kuznetsov, B.N.; Baryshnikov, S.V. [Institute of Chemistry and Chemical Technology SB RAS, K. Marx Str., Krasnoyarsk 660049 (Russian Federation); Cebolla, V.L. [Instituto de Carboquimica, CSIC, Zaragoza (Spain); Weber, J.V.; Collura, S.; Finqueneisel, G.; Zimny, T. [Laboratoire de Chimie et Applications, Universite de Metz, IUT, rue V. Demange, 57500 Saint Avold (France)

    2006-06-01

    The pyrolysis in a hydrogen atmosphere of pine wood and synthetic polymers (polyethylene and polypropylene) mixtures was studied in a rotating autoclave. The effects of reaction temperature, wood/polymers mixture composition and catalysts, on the mixtures conversion into liquids and gases were established and discussed. The used catalysts were pyrrhotite and haematite materials activated by mechanochemical treatment. In the co-liquefaction processes the interaction between fragments of wood and polymers thermal decomposition took place. This results in non-additive increase of the wood/polymers conversion degree by 10-15wt.% and of the yield of distillate fractions by 14-19wt.%. Iron ore materials were found catalytically active in the process of hydropyrolysis of wood/polymers mixtures. By using these catalysts a significant increase of the distillable liquids amounts (by 14-21wt.%) and a sharp decrease of olefins and cycloparaffins content (by approximately two to three times) were observed. (author)

  16. Synthetic Polymers as Gasoline Thickening Agents

    Science.gov (United States)

    1944-10-02

    gels Involved the use of asphalts , gums, factices, carbon black, and miscellaneous organic solids. When gels were obtained they were weak and had a...polymer In the F-614 gel gave a very veak, friable gel. Attempts to cross-link Vlstanex In solution vlth di- Isocyanates or vlth sulfur In the... asphalt mixture used as the fluid base of their magnesium pastes was investigated. Only Vlstanex would dissolve in this material. The use of toluene

  17. Hybrid Block Copolymers Constituted by Peptides and Synthetic Polymers: An Overview of Synthetic Approaches, Supramolecular Behavior and Potential Applications

    Directory of Open Access Journals (Sweden)

    Jordi Puiggalí

    2013-02-01

    Full Text Available Hybrid block copolymers based on peptides and synthetic polymers, displaying different types of topologies, offer new possibilities to integrate the properties and functions of biomacromolecules and synthetic polymers in a single hybrid material. This review provides a current status report of the field concerning peptide-synthetic polymer hybrids. The first section is focused on the different synthetic approaches that have been used within the last three years for the preparation of peptide-polymer hybrids having different topologies. In the last two sections, the attractive properties, displayed in solution or in the solid state, together with the potential applications of this type of macromolecules or supramolecular systems are highlighted.

  18. 21 CFR 874.3620 - Ear, nose, and throat synthetic polymer material.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ear, nose, and throat synthetic polymer material..., and throat synthetic polymer material. (a) Identification. Ear, nose, and throat synthetic polymer material is a device material that is intended to be implanted for use as a space-occupying substance in...

  19. Natural and synthetic polymers in fabric and home care applications

    Science.gov (United States)

    Paderes, Monissa; Ahirwal, Deepak; Fernández Prieto, Susana

    2017-07-01

    Polymers can be tailored to provide different benefits in Fabric & Home Care formulations depending on the monomers and modifications used, such as avoiding dye transfer inhibition in the wash, modifying the surface of tiles or increasing the viscosity and providing suspension properties to consumer products. Specifically, the rheology modification properties of synthetic and natural polymers are discussed in this chapter. The choice of a polymeric rheology modifier will depend on the formulation ingredients (charges, functional groups), the type and the amount of surfactants, the pH and the desired rheology modification. Natural polymeric rheology modifiers have been traditionally used in the food industry, being xanthan gum one of the most well-known ones. On the contrary, synthetic rheology modifiers are preferably used in paints & coats, textile printing and cleaning products.

  20. Synthetic polymers and their potential as genetic materials.

    Science.gov (United States)

    Pinheiro, Vitor B; Loakes, David; Holliger, Philipp

    2013-02-01

    DNA and RNA are the only known natural genetic materials. Systematic modification of each of their chemical building blocks (nucleobase, sugar, and phosphate) has enabled the study of the key properties that make those nucleic acids genetic materials. All three moieties contribute to replication and, significantly, all three moieties can be replaced by synthetic analogs without loss of function. Synthetic nucleic acid polymers capable of storing and propagating information not only expand the central dogma, but also highlight that DNA and RNA are not unique chemical solutions for genetic information storage. By considering replication as a question of information transfer, we propose that any polymer that can be replicated could serve as a genetic material. Copyright © 2013 WILEY Periodicals, Inc.

  1. Application of natural and synthetic polymers in a production of paper

    OpenAIRE

    Jovanović Slobodan; Krgović Milorad; Ošap Danijela

    2007-01-01

    This work gives the review of most frequently used natural and synthetic polymers in production of paper, board and cardboard. Physical and chemical interaction of natural and synthetic polymers with cellulose fibers, and thus the way these polymers influence the improvement of both production process and the paper characteristics, have been presented.

  2. Application of natural and synthetic polymers in a production of paper

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan

    2007-01-01

    Full Text Available This work gives the review of most frequently used natural and synthetic polymers in production of paper, board and cardboard. Physical and chemical interaction of natural and synthetic polymers with cellulose fibers, and thus the way these polymers influence the improvement of both production process and the paper characteristics, have been presented.

  3. The convergence of synthetic organic and polymer chemistries.

    Science.gov (United States)

    Hawker, Craig J; Wooley, Karen L

    2005-08-19

    Several recent conceptual advances, which take advantage of the design criteria and practical techniques of molecular-level control in organic chemistry, allow preparation of well-defined polymers and nanostructured materials. Two trends are clear: the realization that synthesis of complex macromolecules poses major challenges and opportunities and the expectation that such materials will exhibit distinctive properties and functions. Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins (for example, three-dimensional folded structure) and other natural materials. These macromolecules have far-reaching potential for the study of molecular-level behavior at interfaces, in thin films, and in solution, while also enabling the development of encapsulation, drug-delivery, and nanoscale-patterning technologies.

  4. The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

    Science.gov (United States)

    Suaria, Giuseppe; Avio, Carlo G.; Mineo, Annabella; Lattin, Gwendolyn L.; Magaldi, Marcello G.; Belmonte, Genuario; Moore, Charles J.; Regoli, Francesco; Aliani, Stefano

    2016-01-01

    The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea. PMID:27876837

  5. The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

    Science.gov (United States)

    Suaria, Giuseppe; Avio, Carlo G.; Mineo, Annabella; Lattin, Gwendolyn L.; Magaldi, Marcello G.; Belmonte, Genuario; Moore, Charles J.; Regoli, Francesco; Aliani, Stefano

    2016-11-01

    The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea.

  6. Characteristic and Synthetic Approach of Molecularly Imprinted Polymer

    Directory of Open Access Journals (Sweden)

    Kyung Ho Row

    2006-06-01

    Full Text Available Molecularly imprinted polymers (MIP exhibiting high selectivity and affinity tothe predetermined molecule (template are now seeing a fast growing research. However,optimization of the imprinted products is difficult due to the fact that there are manyvariables to consider, some or all of which can potentially impact upon the chemical,morphological and molecular recognition properties of the imprinted materials. This reviewpresent a summary of the principal synthetic considerations pertaining to good practice in thepolymerization aspects of molecular imprinting, and is primarily aimed at researcher familiarwith molecular imprinting methods but with little or no prior experience in polymersynthesis. The synthesis, characteristic, effect of molecular recognition and differentpreparation methods of MIP in recent few years are discussed in this review, unsolvedproblems and possible developments of MIP were also been briefly discussed.

  7. Towards XNA nanotechnology: new materials from synthetic genetic polymers.

    Science.gov (United States)

    Pinheiro, Vitor B; Holliger, Philipp

    2014-06-01

    Nucleic acids display remarkable properties beyond information storage and propagation. The well-understood base pairing rules have enabled nucleic acids to be assembled into nanostructures of ever increasing complexity. Although nanostructures can be constructed using other building blocks, including peptides and lipids, it is the capacity to evolve that sets nucleic acids apart from all other nanoscale building materials. Nonetheless, the poor chemical and biological stability of DNA and RNA constrain their applications. Recent advances in nucleic acid chemistry and polymerase engineering enable the synthesis, replication, and evolution of a range of synthetic genetic polymers (XNAs) with improved chemical and biological stability. We discuss the impact of this technology on the generation of XNA ligands, enzymes, and nanostructures with tailor-made chemistry. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Identification of Synthetic Polymers and Copolymers by Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry

    Science.gov (United States)

    Kusch, Peter

    2014-01-01

    An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In…

  9. Biocomposites of non-crosslinked natural and synthetic polymers.

    Science.gov (United States)

    Coombes, A G A; Verderio, E; Shaw, B; Li, X; Griffin, M; Downes, S

    2002-05-01

    Biocomposite films comprising a non-crosslinked, natural polymer (collagen) and a synthetic polymer, poly(epsilon-caprolactone) (PCL), have been produced by impregnation of lyophilised collagen mats with a solution of PCL in dichloromethane followed by solvent evaporation. This approach avoids the toxicity problems associated with chemical crosslinking. Distinct changes in film morphology, from continuous surface coating to open porous format, were achieved by variation of processing parameters such as collagen:PCL ratio and the weight of the starting lyophilised collagen mat. Collagenase digestion indicated that the collagen content of 1:4 and 1:8 collagen:PCL biocomposites was almost totally accessible for enzymatic digestion indicating a high degree of collagen exposure for interaction with other ECM proteins or cells contacting the biomaterial surface. Much reduced collagen exposure (around 50%) was measured for the 1:20 collagen:PCL materials. These findings were consistent with the SEM examination of collagen:PCL biocomposites which revealed a highly porous morphology for the 1:4 and 1:8 blends but virtually complete coverage of the collagen component by PCL in the 1:20 samples. Investigations of the attachment and spreading characteristics of human osteoblast (HOB) cells on PCL films and collagen:PCL materials respectively, indicated that HOB cells poorly recognised PCL but attachment and spreading were much improved on the biocomposites. The non-chemically crosslinked, collagen:PCL biocomposites described are expected to provide a useful addition to the range of biomaterials and matrix systems for tissue engineering.

  10. Synthetic polymers and methods of making and using the same

    Science.gov (United States)

    Daily, Michael D.; Grate, Jay W.; Mo, Kai-For

    2016-06-14

    Monomer embodiments that can be used to make polymers, such as homopolymers, heteropolymers, and that can be used in particular embodiments to make sequence-defined polymers are described. Also described are methods of making polymers using such monomer embodiments. Methods of using the polymers also are described.

  11. Understanding the folding process of synthetic polymers by small ...

    Indian Academy of Sciences (India)

    This two-point interaction between the folding agent and the polymer backbone leads to a folding of the polymer chain, which was readily monitored by NMR titrations. The effect of various parameters, such as structures of the folding agent and polymer, and the solvent composition, on the folding propensities of the polymer ...

  12. Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers

    Science.gov (United States)

    Hilado, C. J.; Soriano, J. A.; Kosola, K. L.

    1977-01-01

    The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.

  13. Antifouling Activity of Synthetic Alkylpyridinium Polymers Using the Barnacle Model

    Directory of Open Access Journals (Sweden)

    Veronica Piazza

    2014-04-01

    Full Text Available Polymeric alkylpyridinium salts (poly-APS isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite as a model (cyprids and II stage nauplii larvae in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC50 after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC50: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC50 of 4.83 and 1.86 mg/L.

  14. Antifouling activity of synthetic alkylpyridinium polymers using the barnacle model.

    Science.gov (United States)

    Piazza, Veronica; Dragić, Ivanka; Sepčić, Kristina; Faimali, Marco; Garaventa, Francesca; Turk, Tom; Berne, Sabina

    2014-04-02

    Polymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC₅₀) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC₅₀: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC₅₀ of 4.83 and 1.86 mg/L.

  15. Understanding the folding process of synthetic polymers by small ...

    Indian Academy of Sciences (India)

    WINTEC

    was readily monitored by NMR titrations. The effect of various parameters, such as structures of the folding agent and polymer, and the solvent composition, on the folding propensities of the polymer was studied. Keywords. Polyimides; NMR titration; foldamer; folding agent. 1. Introduction. Control of polymer conformation in ...

  16. Control of polymer-packing orientation in thin films through synthetic tailoring of backbone coplanarity

    KAUST Repository

    Chen, Mark S.

    2013-10-22

    Controlling solid-state order of π-conjugated polymers through macromolecular design is essential for achieving high electronic device performance; yet, it remains a challenge, especially with respect to polymer-packing orientation. Our work investigates the influence of backbone coplanarity on a polymer\\'s preference to pack face-on or edge-on relative to the substrate. Isoindigo-based polymers were synthesized with increasing planarity by systematically substituting thiophenes for phenyl rings in the acceptor comonomer. This increasing backbone coplanarity, supported by density functional theory (DFT) calculations of representative trimers, leads to the narrowing of polymer band gaps as characterized by ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy and cyclic voltammetry. Among the polymers studied, regiosymmetric II and TII polymers exhibited the highest hole mobilities in organic field-effect transistors (OFETs), while in organic photovoltaics (OPVs), TBII polymers that display intermediate levels of planarity provided the highest power conversion efficiencies. Upon thin-film analysis by atomic force microscropy (AFM) and grazing-incidence X-ray diffraction (GIXD), we discovered that polymer-packing orientation could be controlled by tuning polymer planarity and solubility. Highly soluble, planar polymers favor face-on orientation in thin films while the less soluble, nonplanar polymers favor an edge-on orientation. This study advances our fundamental understanding of how polymer structure influences nanostructural order and reveals a new synthetic strategy for the design of semiconducting materials with rationally engineered solid-state properties. © 2013 American Chemical Society.

  17. Biomedical inorganic polymers bioactivity and applications of natural and synthetic polymeric inorganic molecules

    CERN Document Server

    Müller, Werner E G; Schröder, Heinz C; Schroder, Heinz C

    2014-01-01

    In recent years, inorganic polymers have attracted much attention in nano-biomedicine, in particular in the area of regenerative medicine and drug delivery. This growing interest in inorganic polymers has been further accelerated by the development of new synthetic and analytical methods in the field of nanotechnology and nanochemistry. Examples for biomedical inorganic polymers that had been proven to exhibit biomedical effects and/or have been applied in preclinical or clinical trials are polysilicate / silica glass (such as naturally formed "biosilica" and synthetic "bioglass") and inorganic polyphosphate. Some members of the mentioned biomedical inorganic polymers have already been applied e.g. as "bioglass" for bone repair and bone tissue engineering, or they are used in food processing and in dental care (inorganic polyphosphates). However, there are a number of further biological and medicinal properties of these polymers, which have been elucidated in the last few years but not yet been applied for tr...

  18. Main-chain organometallic polymers: synthetic strategies, applications, and perspectives.

    Science.gov (United States)

    Williams, Kyle A; Boydston, Andrew J; Bielawski, Christopher W

    2007-05-01

    Main-chain organometallic polymers utilize transition metal-organic ligand complexes as primary components of their backbones. These hybrid materials effectively integrate the physical and electronic properties of organic polymers with the physical, electronic, optical, and catalytic properties of organometallic complexes. Combined with the rich and continuously growing array of ligands for transition metals, these materials have outstanding potential for use in a broad range of applications. This tutorial review discusses the major classes of main-chain organometallic polymers, including coordination polymers, poly(metal acetylide)s, and poly(metallocene)s. Emphasis is placed on their synthesis, characterization, physical properties, and applications, as well as ongoing challenges and limitations. These discussions are supplemented with highlights from the recent literature. The review concludes with perspectives on the current status of the field, as well as opportunities that lie just beyond its frontier.

  19. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  20. Synthetic genetic polymers capable of heredity and evolution

    DEFF Research Database (Denmark)

    Pinheiro, Vitor B; Taylor, Alexander I; Cozens, Christopher

    2012-01-01

    in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity......Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored...... for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage....

  1. Biopores/membrane proteins in synthetic polymer membranes.

    Science.gov (United States)

    Garni, Martina; Thamboo, Sagana; Schoenenberger, Cora-Ann; Palivan, Cornelia G

    2017-04-01

    Mimicking cell membranes by simple models based on the reconstitution of membrane proteins in lipid bilayers represents a straightforward approach to understand biological function of these proteins. This biomimetic strategy has been extended to synthetic membranes that have advantages in terms of chemical and mechanical stability, thus providing more robust hybrid membranes. We present here how membrane proteins and biopores have been inserted both in the membrane of nanosized and microsized compartments, and in planar membranes under various conditions. Such bio-hybrid membranes have new properties (as for example, permeability to ions/molecules), and functionality depending on the specificity of the inserted biomolecules. Interestingly, membrane proteins can be functionally inserted in synthetic membranes provided these have appropriate properties to overcome the high hydrophobic mismatch between the size of the biomolecule and the membrane thickness. Functional insertion of membrane proteins and biopores in synthetic membranes of compartments or in planar membranes is possible by an appropriate selection of the amphiphilic copolymers, and conditions of the self-assembly process. These hybrid membranes have new properties and functionality based on the specificity of the biomolecules and the nature of the synthetic membranes. Bio-hybrid membranes represent new solutions for the development of nanoreactors, artificial organelles or active surfaces/membranes that, by further gaining in complexity and functionality, will promote translational applications. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider. Copyright © 2016. Published by Elsevier B.V.

  2. Enzyme sensitive synthetic polymer micelles based on the azobenzene motif.

    Science.gov (United States)

    Rao, Jingyi; Khan, Anzar

    2013-09-25

    In this study, we investigate the potential of an artificial structural motif, azobenzene, in the preparation of enzyme sensitive polymeric nanostructures. For this purpose, an azobenzene linkage is established at the copolymer junction of an amphiphilic diblock copolymer. This polymer assembles into a micellar structure in water. Treatment with the enzyme azoreductase, in the presence of coenzyme NADPH, results in the cleavage of the azo-based copolymer junction and disruption of the micellar assembly. These results suggest that azobenezene is a useful non-natural structural motif for the preparation of enzyme responsive polymer nanoparticles. Due to the presence of azoreductase in the human intestine, such nanomaterials are anticipated to find applicability in the arena of colon-specific delivery systems.

  3. Novel polymer materials for protecting crew and structural elements of orbital station against microorganisms attack throughout long-term operation

    Science.gov (United States)

    Savelyev, Yu.; Rudenko, A.; Robota, L.; Koval, E.; Savelyeva, O.; Markovskaya, L.; Veselov, V.

    2009-01-01

    Novel polyurethanes, polyamidourethanes and polyurethane foams of stable to biocorrosion were synthesized. The polymers possess fungicidal/fungistatic and bactericidal/bacteriostatic activity. After the biological tests with using of mold fungi and yeasts, polymers totally keep their main exploitation characteristics: for most of polymers coefficients of strength and elasticity keeping are equal of 100%. Most of them possess the fungicidal properties of zero balls, according to the State Standard. Life-firmness investigation of the most aggressive extremophiles: mold fungi Penicillium and Aspergillus on the polymer surfaces showed that for some samples it made up from 3 to 10 days. Some polymers possess both anti-micotic and anti-bacterial action. Based on investigation results a special technological scheme of assured human protection against microorganisms attack in specific condition of his existence are to be elaborated.

  4. Impinging jet study of the deposition of colloidal particles on synthetic polymer (Zeonor)

    DEFF Research Database (Denmark)

    Vlček, Jakub; Lapčík, Lubomír; Cech, Jiri

    2014-01-01

    In this study, an impinging jet deposition experiments were performed on synthetic polymer (Zeonor) original and by micro-embossing modified substrates with exactly defined topology as confirmed by AFM and SEM. Deposition experiments were performed at ambient temperature and at selected flow regi...

  5. Synthetic strategies for the fluorescent labeling of epichlorohydrin-branched cyclodextrin polymers

    OpenAIRE

    Malanga, Milo; B?lint, Mih?ly; Pusk?s, Istv?n; Tuza, Kata; Sohajda, Tam?s; Jicsinszky, L?szl?; Szente, Lajos; Fenyvesi, ?va

    2014-01-01

    Summary The fluorescent tagging of cyclodextrin derivatives enlarges their spectroscopic properties thus generating chemosensors, biological tools for visualization and sophisticated photoresponsive devices. Cyclodextrin polymers, due to the cooperative interactions, exhibit additional properties compared to their monomeric counterpart. These macromolecules can be prepared either in well water-soluble form or as gels of high swelling. Two versatile synthetic strategies for introducing a fluor...

  6. Synthetic Reference Materials Based on Polymer Films for the Control of Welding Fumes Composition

    Science.gov (United States)

    Kuznetsova, O. V.; Kuznetsova, A. N.; Begunova, L. A.

    2017-04-01

    Analysis of the current hygienic situation in the welding production showed that the intensification of welding processes involves the deterioration of air quality, which negatively affects the welders health. Welders are exposed to a variety of metal fumes, including manganese that may elevate the risk for neurological diseases. The control of metals concentration in the air of the working area is difficult due to the lack of reference materials. The creation of reference materials of welding fumes composition is a challenge due to chemical characteristics of their physical properties. Synthetic samples in a form of the polymer film containing powder particles of welding fumes were create. Studies on the selection of the polymer were done. Experiments proved that the qualitative materials of synthetic welding fumes are obtained by using polyvinyl alcohol. The metals concentration in the samples was determined by X-ray fluorescence analysis. The obtained data demonstrates indirectly the uniform distribution of welding fumes powder particles on the polymer film.

  7. Biologically inspired synthetic gecko adhesive from hard polymer microfiber arrays

    Science.gov (United States)

    Lee, Jongho

    Inspiration from nature and development of nano/micro-technology suggest new types of smart adhesives. Gecko's fast wall-climbing and upside-down-walking even on contaminated surfaces inspire the development of easily attachable and easily releasable, durable, self-cleaning synthetic adhesives. Advances in nano/micro-technology enable the fabrication of gecko-like nano/micro-structures. However, producing structures that exhibit a close resemblance to those of gecko is still challenging. This thesis explores achieving the key properties of the natural gecko adhesive with relatively simple nano/micro-structures consisting of synthetic materials. Hard material, comparable to the natural gecko structures, was used, and the surface geometry was modified to achieve novel adhesion properties. Important properties of the fabricated microfiber arrays were characterized and compared with the natural gecko adhesives using a custom-made force sensor apparatus. The high-aspect-ratio of the microfiber arrays showed similar novel properties, including easiness in attachment and release, durability, self-cleaning capability, and directional dependence of adhesion/friction properties, similar to natural gecko surfaces.

  8. Characterization and degradation studies on synthetic polymers for aerospace application

    Science.gov (United States)

    Hsu, M. T. S.

    1982-01-01

    The anti-misting additive for jet fuels known as FM-9 (proprietary polymer) was characterized by elemental analysis, solubility studies and molecular weight determination. Physical properties of surface tension, viscosity, specific gravity and other physical parameters were determined. These results are compared with properties of polyisobutylene and fuels modified with the same; the misting characteristics of polyisobutylene and FM-9 in Jet A fuel are included. Characterization and degradation of phthalocyanine and its derivatives were accomplished by use of a mass spectrometer and a pyroprobe solid pyrolyzer. Metal phthalocyanine tetracarboxylic acids and phthalocyanine-tetraamine cured epoxies were studied. Epoxy/graphite composite panels were exposed to a NASA-Ames radiant panel fire simulator in the flaming and non-flaming modes; toxic gases of HCN and HZS were measured along with oxygen, Co2, Co, and organic gases.

  9. Synthetic polymers as drug-delivery vehicles in medicine.

    Science.gov (United States)

    Neuse, Eberhard W

    2008-01-01

    Cancerous diseases present a formidable health problem worldwide. While the chemotherapy of cancer, in conjunction with other treatment modalities, has reached a significant level of maturity, efficacious use of such agents is still restricted by numerous pharmacological deficiencies, such as poor water solubility, short serum circulation lifetimes, and low bioavailability resulting from lack of affinity to cancer tissue and inadequate mechanisms of cell entry. More critically still, most drugs suffer from toxic side effects and a risk of drug resistance. The class of platinum anticancer drugs, although outstandingly potent, is particularly notorious in that respect. Among the countless methods developed in recent years in an effort to overcome these deficiencies, the technology of polymer-drug conjugation stands out as a particularly advanced treatment modality. The strategy involves the bioreversible binding, conjugating, of a medicinal agent to a water-soluble macromolecular carrier. Following pharmacokinetic pathways distinctly different from those of the common, nonpolymeric drugs, the conjugate so obtained will act as a prodrug providing safe transport of the bioactive agent to and into the affected, that is, cancerous cell for its ultimate cell-killing activity. The present treatise will acquaint us with the pharmacological fundamentals of this drug delivery approach, applied here specifically to the metalorganic platinum-type drug systems and the organometallic ferrocene drug model. We will see just how this technology leads to conjugates distinctly superior in antiproliferative activity to cisplatin, a clinically used antitumor agent used here as a standard. Polymer-drug conjugation involving metal-based and other medicinal agents has unquestionably matured to a practical tool to the pharmaceutical scientist, and all indications point to an illustrious career for this nascent drug delivery approach in the fight against cancer and other human maladies.

  10. Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles

    Science.gov (United States)

    Hood, Matthew A.; Mari, Margherita; Muñoz-Espí, Rafael

    2014-01-01

    This article reviews the recent advances and challenges in the preparation of polymer/inorganic hybrid nanoparticles. We mainly focus on synthetic strategies, basing our classification on whether the inorganic and the polymer components have been formed in situ or ex situ, of the hybrid material. Accordingly, four types of strategies are identified and described, referring to recent examples: (i) ex situ formation of the components and subsequent attachment or integration, either by covalent or noncovalent bonding; (ii) in situ polymerization in the presence of ex situ formed inorganic nanoparticles; (iii) in situ precipitation of the inorganic components on or in polymer structures; and (iv) strategies in which both polymer and inorganic component are simultaneously formed in situ. PMID:28788665

  11. Synthetic Effect of Vivid Shark Skin and Polymer Additive on Drag Reduction Reinforcement

    Directory of Open Access Journals (Sweden)

    Huawei Chen

    2014-06-01

    Full Text Available Natural shark skin has a well-demonstrated drag reduction function, which is mainly owing to its microscopic structure and mucus on the body surface. In order to improve drag reduction, it is necessary to integrate microscopic drag reduction structure and drag reduction agent. In this study, two hybrid approaches to synthetically combine vivid shark skin and polymer additive, namely, long-chain grafting and controllable polymer diffusion, were proposed and attempted to mimic such hierarchical topography of shark skin without waste of polymer additive. Grafting mechanism and optimization of diffusion port were investigated to improve the efficiency of the polymer additive. Superior drag reduction effects were validated, and the combined effect was also clarified through comparison between drag reduction experiments.

  12. Biocompatible synthetic and semi-synthetic polymers - A patent preliminary analysis.

    Science.gov (United States)

    Ranganathan, Balu; Miller, Charles; Sinskey, Anthony

    2017-10-23

    Bioengineering has come of ages by setting up spare parts manufacturing units to be used in human body such as invasive implants and interventional controlled drug delivery in vivo systems. As a matter of fact patients on basis of their fiscal strength have the option of undergoing prophylactic tactical manoeuvre for longevity. In this sphere of invasive implants, biocompatible polymer implants are a state of the art cutting edge technology with outstanding innovations leading to number of very successful start-up companies with a plethora of patent portfolios. From 2000 onwards, around fifteen years on patent filings and grants for biocompatible polymers are expanding. Pair Bulk Data (PBD) portal was used to mine patent portfolios. In this patent preliminary analysis report, patents from 2000 to 2015 were evaluated using 317(c) filings, grants and classifications data for poly(vinyl alcohol) (PVA), poly(glycolic acid) (PGA), poly(hydroxyalkanoates) (PHAs) and poly(lactic acid) (PLA). Patent portfolio of Commercial giant Thepa Inc. was analysed for Cooperative Patent Classification (CPC) sections. This patent portfolio preliminary analysis embarks into patent analysis for New Product Development (NPD) for corporate R&D investment managerial decisions and on government advocacy for federal funding which is decisive for developmental advances. An in-depth patent portfolio investigation with return of investment (RoI) is in the pipeline. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  13. Perturbations of cellular membranes with synthetic polymers and ultrafast lasers

    Science.gov (United States)

    Kelly, Christopher Vaughn-Daigneau

    This dissertation examines the response of the plasma membrane to perturbations by synthetic nanoparticles and ultra-fast laser pulses. Both model membranes and living cells were examined in to characterize membrane disruption and the biological response to perturbation. These studies provide a deeper understanding of cell biology and guide the design of effective nanoparticle- or laser-based therapies, as well as warning about unintended exposure. In regards to membrane disruption by pulsed-laser irradiation, irradiation induced giant plasma membrane vesicles (GPMVs) on the surface of the living cell. This process involved the incorporation of material from the extracellular media into both the cytoplasm and the GPMV as the cell responded to the intense pressure and temperature gradients induced by irradiation and the subsequent cavitation. Further, the cell exposed phosphotidylserine to the exterior surface of the plasma membrane and GPMV and initiated caspase activity. Single particle tracking of 20 nm fluorescent beads within the GPMVs demonstrated a complex, gelatinous structure within the GPMV. In regards to nanoparticle-based perturbations, techniques such as isothermal titration calorimetry and molecular dynamics were used to investigate the relationship between nanoparticle properties and membrane disruption. Molecular dynamics simulations examined the binding of third-generation poly(amidoamine) dendrimers to phosphatidylcholine bilayers as a function on nanoparticle termination and membrane phase. A potential of mean force was calculated and demonstrated that the charged dendrimers bound to the zwitterionic phospholipids with approximately 50% more free energy release than uncharged dendrimers. Further, the difference in dendrimer binding to gel and fluid lipids was largely due to the hydrophobic interactions between the lipid tails and the non-polar dendrimer moieties. Isothermal titration calorimetry examined the heat release upon interaction between

  14. Frontiers in biomaterials the design, synthetic strategies and biocompatibility of polymer scaffolds for biomedical application

    CERN Document Server

    Cao, Shunsheng

    2014-01-01

    Frontiers in Biomaterials: The Design, Synthetic Strategies and Biocompatibility of Polymer Scaffolds for Biomedical Application, Volume 1" highlights the importance of biomaterials and their interaction with biological system. The need for the development of biomaterials as scaffold for tissue regeneration is driven by the increasing demands for materials that mimic functions of extracellular matrices of body tissues.This ebook covers the latest challenges on the biocompatibility of scaffold overtime after implantation and discusses the requirement of innovative technologies and strategies f

  15. Photoactive Hybrid Catalysts Based on Natural and Synthetic Polymers: A Comparative Overview.

    Science.gov (United States)

    Colmenares, Juan Carlos; Kuna, Ewelina

    2017-05-12

    In the present review, we would like to draw the reader's attention to the polymer-based hybrid materials used in photocatalytic processes for efficient degradation of organic pollutants in water. These inorganic-organic materials exhibit unique physicochemical properties due to the synergistic effect originating from the combination of individual elements, i.e., photosensitive metal oxides and polymeric supports. The possibility of merging the structural elements of hybrid materials allows for improving photocatalytic performance through (1) an increase in the light-harvesting ability; (2) a reduction in charge carrier recombination; and (3) prolongation of the photoelectron lifetime. Additionally, the great majority of polymer materials exhibit a high level of resistance against ultraviolet irradiation and improved corrosion resistance. Taking into account that the chemical and environmental stability of the hybrid catalyst depends, to a great extent, on the functional support, we highlight benefits and drawbacks of natural and synthetic polymer-based photocatalytic materials and pay special attention to the fact that the accessibility of synthetic polymeric materials derived from petroleum may be impeded due to decreasing amounts of crude oil. Thus, it is necessary to look for cheap and easily available raw materials like natural polymers that come from, for instance, lignocellulosic wastes or crustacean residues to meet the demand of the "plastic" market.

  16. Glycoproteins functionalized natural and synthetic polymers for prospective biomedical applications: A review.

    Science.gov (United States)

    Tabasum, Shazia; Noreen, Aqdas; Kanwal, Arooj; Zuber, Mohammad; Anjum, Muhammad Naveed; Zia, Khalid Mahmood

    2017-05-01

    Glycoproteins have multidimensional properties such as biodegradability, biocompatibility, non-toxicity, antimicrobial and adsorption properties; therefore, they have wide range of applications. They are blended with different polymers such as chitosan, carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), polycaprolactone (PCL), heparin, polystyrene fluorescent nanoparticles (PS-NPs) and carboxyl pullulan (PC) to improve their properties like thermal stability, mechanical properties, resistance to pH, chemical stability and toughness. Considering the versatile charateristics of glycoprotein based polymers, this review sheds light on synthesis and characterization of blends and composites of glycoproteins, with natural and synthetic polymers and their potential applications in biomedical field such as drug delivery system, insulin delivery, antimicrobial wound dressing uses, targeting of cancer cells, development of anticancer vaccines, development of new biopolymers, glycoproteome research, food product and detection of dengue glycoproteins. All the technical scientific issues have been addressed; highlighting the recent advancement. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. A novel view of modelling interactions between synthetic and biological polymers via docking

    Science.gov (United States)

    Tsvetkov, Vladimir B.; Serbin, Alexander V.

    2012-12-01

    Multipoint interactions between synthetic and natural polymers provide a promising platform for many topical applications, including therapeutic blockage of virus-specific targets. Docking may become a useful tool for modelling of such interactions. However, the rigid docking cannot be correctly applied to synthetic polymers with flexible chains. The application of flexible docking to these polymers as whole macromolecule ligands is also limited by too many possible conformations. We propose to solve this problem via stepwise flexible docking. Step 1 is docking of separate polymer components: (1) backbone units ( BU), multi-repeated along the chain, and (2) side groups ( SG) consisting of functionally active elements ( SG F ) and bridges ( SG B ) linking SG F with BU. At this step, probable binding sites locations and binding energies for the components are scored. Step 2 is docking of component-integrating models: [ BU] m , SG = SG F -SG B , BU-SG, BU-BU( SG) -BU, BU( SG) -[ BU] m -BU( SG), and [ BU var ( SG var )] m . Every modelling level yields new information, including how the linkage of various components influences on the ligand—target contacts positioning, orientation, and binding energy in step-by-step approximation to polymeric ligand motifs. Step 3 extrapolates the docking results to real-scale macromolecules. This approach has been demonstrated by studying the interactions between hetero-SG modified anionic polymers and the N-heptad repeat region tri-helix core of the human immunodeficiency virus type 1 ( HIV-1) envelope glycoprotein gp41, the key mediator of HIV-1 fusion during virus entry. The docking results are compared to real polymeric compounds, acting as HIV-1 entry inhibitors in vitro. This study clarifies the optimal macromolecular design for the viral fusion inhibition and drug resistance prevention.

  18. Preparation of a zeolite-modified polymer monolith for identification of synthetic colorants in lipsticks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiqi; Li, Zheng [College of Chemistry, Jilin University, Changchun 130012 (China); Niu, Qian [Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Ma, Jiutong [College of Chemistry, Jilin University, Changchun 130012 (China); Jia, Qiong, E-mail: jiaqiong@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

    2015-10-30

    Graphical abstract: Poly(methacrylic acid-ethylene dimethacrylate) monolithic column embedded with zeolites was prepared and employed for the polymer monolith microextraction of colorants combined with HPLC. - Highlights: • Zeolite, as a kind of mesoporous material, was firstly combined with PMME. • Zeolite@poly(MAA-EDMA) monolith columns were prepared for the enrichment of colorants. • Zeolite@poly(MAA-EDMA) monolith columns demonstrated relatively high extraction capacity. - Abstract: A novel zeolite-modified poly(methacrylic acid-ethylenedimethacrylate) (zeolite@poly(MAA-EDMA)) monolithic column was prepared with the in situ polymerization method and employed in polymer monolith microextraction for the separation and preconcentration of synthetic colorants combined with high performance liquid chromatography. The polymer was characterized by scanning electronmicroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermo-gravimetric analysis. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. The method was applied to the determination of synthetic colorants in lipsticks with recoveries ranged from 70.7% to 109.7%. Compared with conventional methacrylic acid-based monoliths, the developed monolith exhibited high enrichment capacity because of the introduction of zeolites into the preparation process. The extraction efficiency followed the order: zeolite@poly(MAA-EDMA) > poly(MAA-EDMA) > direct HPLC analysis.

  19. Synthetic strategies for the fluorescent labeling of epichlorohydrin-branched cyclodextrin polymers

    Directory of Open Access Journals (Sweden)

    Milo Malanga

    2014-12-01

    Full Text Available The fluorescent tagging of cyclodextrin derivatives enlarges their spectroscopic properties thus generating chemosensors, biological tools for visualization and sophisticated photoresponsive devices. Cyclodextrin polymers, due to the cooperative interactions, exhibit additional properties compared to their monomeric counterpart. These macromolecules can be prepared either in well water-soluble form or as gels of high swelling. Two versatile synthetic strategies for introducing a fluorescent tag (rhodamine, fluorescein, nitrobenzofuran or coumarin into the water-soluble epichlorohydrin branched cyclodextrin polymers were worked out and compared. The fluorescent labeling was realized in three steps: 1 building in azido moieties, 2 transforming the azido groups into amino groups and 3 coupling the proper fluorescent compound to the amino groups. The other strategy started by functionalization of the monomer prior to the branching. Either the fluorescent-labeled monomer or the intermediate azido derivative of the monomer was branched. Further tuning of the properties of the polymer was achieved via branching of the methylated cyclodextrin derivative. The key intermediates and the fluorescent final products were characterized by various spectroscopic techniques and capillary electrophoresis. The applied synthetic routes were evaluated based on the molecular weight, cyclodextrin content of the products and the efficiency of labeling.

  20. Synthetic strategies for the fluorescent labeling of epichlorohydrin-branched cyclodextrin polymers.

    Science.gov (United States)

    Malanga, Milo; Bálint, Mihály; Puskás, István; Tuza, Kata; Sohajda, Tamás; Jicsinszky, László; Szente, Lajos; Fenyvesi, Éva

    2014-01-01

    The fluorescent tagging of cyclodextrin derivatives enlarges their spectroscopic properties thus generating chemosensors, biological tools for visualization and sophisticated photoresponsive devices. Cyclodextrin polymers, due to the cooperative interactions, exhibit additional properties compared to their monomeric counterpart. These macromolecules can be prepared either in well water-soluble form or as gels of high swelling. Two versatile synthetic strategies for introducing a fluorescent tag (rhodamine, fluorescein, nitrobenzofuran or coumarin) into the water-soluble epichlorohydrin branched cyclodextrin polymers were worked out and compared. The fluorescent labeling was realized in three steps: 1) building in azido moieties, 2) transforming the azido groups into amino groups and 3) coupling the proper fluorescent compound to the amino groups. The other strategy started by functionalization of the monomer prior to the branching. Either the fluorescent-labeled monomer or the intermediate azido derivative of the monomer was branched. Further tuning of the properties of the polymer was achieved via branching of the methylated cyclodextrin derivative. The key intermediates and the fluorescent final products were characterized by various spectroscopic techniques and capillary electrophoresis. The applied synthetic routes were evaluated based on the molecular weight, cyclodextrin content of the products and the efficiency of labeling.

  1. Mineralization of Synthetic Polymer Scaffolds: A Bottom-upApproach for the Development of Artificial Bone

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jie; Viengkham, Malathong; Bertozzi, Carolyn R.

    2004-09-27

    The controlled integration of organic and inorganic components confers natural bone with superior mechanical properties. Bone biogenesis is thought to occur by templated mineralization of hard apatite crystals by an elastic protein scaffold, a process we sought to emulate with synthetic biomimetic hydrogel polymers. Crosslinked polymethacrylamide and polymethacrylate hydrogels were functionalized with mineral-binding ligands and used to template the formation of hydroxyapatite. Strong adhesion between the organic and inorganic materials was achieved for hydrogels functionalized with either carboxylate or hydroxy ligands. The mineral-nucleating potential of hydroxyl groups identified here broadens the design parameters for synthetic bone-like composites and suggests a potential role for hydroxylated collagen proteins in bone mineralization.

  2. Concentration-response data on toxicity of pyrolysis gases from six synthetic polymers

    Science.gov (United States)

    Hilado, C. J.; Huttlinger, N. V.

    1978-01-01

    Concentration-response data are presented on the toxic effects of the pyrolysis gases from six synthetic polymers on Swiss Webster male mice, using a toxicity screening test method. The polymers consisted of one sample each of polycarbonate and polystyrene, and two samples each of polyethylene and acrylonitrile-butadiene-styrene (ABS). All six samples were evaluated using the rising temperature program, and three samples were evaluated using the fixed temperature program. The pyrolysis gases from polycarbonate, polyethylene, and ABS appeared to exhibit the concentration-response relationships commonly encountered in toxicology. The polystyrene sample gave variable results; probably due to poor reproducibility of the essentially anaerobic pyrolysis. Carbon monoxide seemed to be the principal toxicant in the pyrolysis gases from polycarbonate and polyethylene, but did not appear to be the principal toxicant in the pyrolysis gases from ABS.

  3. The triazine-based porous organic polymer: Novel synthetic strategy for high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Kuen [Dept. of Chemistry, Hankuk University of Foreign Studies, Yongin (Korea, Republic of)

    2017-02-15

    A new type of microporous polymer has been successively synthesized via a simple polycondensation reaction with the 2,4-diaminotriazine moiety and dianhydride monomer. Diaminotriazine moieties in M1 especially can provide effective branching sites, resulting in high surface areas up to 1150 m{sup 2} /g. In addition, the specific pore structure of the polyimide POP in its solid state can be modified by the surface activation method. Therefore, it can be expected that the resulting material will be a promising candidate for gas storage, and with this synthetic strategy, various type of derivatives will also be optimized.

  4. Clinical efficacy and cost-effectiveness of a new synthetic polymer sheet wound dressing.

    Science.gov (United States)

    Motta, G; Dunham, L; Dye, T; Mentz, J; O'Connell-Gifford, E; Smith, E

    1999-10-01

    Stage II and III pressure ulcers present product development and product choice challenges to manufacturers and professional wound care clinicians respectively. We evaluated the clinical performance and cost of use associated with a new synthetic polymer dressing for the management of these wounds. A total of 10 home healthcare patients, each with a Stage II or III pressure ulcer, were enrolled and randomized for wound treatment using either the new polymer hydrogel wound dressing or the leading market hydrocolloid dressing. Dressings were changed on an as needed basis only. The wounds were assessed weekly and parameters recorded using the Bates-Jensen Pressure Sore Status Tool. In addition, the clinical performance of the dressing and treatment costs were evaluated. The overall healing rate for the two groups was similar. However the new polymer hydrogel dressing was found to have a more favorable overall clinical performance evaluation based largely on its more favorable support of autolytic debridement. The new polymeric dressing also had a more favorable cost of use based on the evaluation. We conclude that the new polymer dressing may be a favorable alternative to the leading market hydrocolloid dressing for the treatment of Stage II and III pressure ulcers due to a better clinical performance and the substantially lower treatment costs associated with its use.

  5. Protein cages and synthetic polymers: a fruitful symbiosis for drug delivery applications, bionanotechnology and materials science.

    Science.gov (United States)

    Rother, Martin; Nussbaumer, Martin G; Renggli, Kasper; Bruns, Nico

    2016-11-07

    Protein cages are hollow protein nanoparticles, such as viral capsids, virus-like particles, ferritin, heat-shock proteins and chaperonins. They have well-defined capsule-like structures with a monodisperse size. Their protein subunits can be modified by genetic engineering at predetermined positions, allowing for example site-selective introduction of attachment points for functional groups, catalysts or targeting ligands on their outer surface, in their interior and between subunits. Therefore, protein cages have been extensively explored as functional entities in bionanotechnology, as drug-delivery or gene-delivery vehicles, as nanoreactors or as templates for the synthesis of organic and inorganic nanomaterials. The scope of functionalities and applications of protein cages can be significantly broadened if they are combined with synthetic polymers on their surface or within their interior. For example, PEGylation reduces the immunogenicity of protein cage-based delivery systems and active targeting ligands can be attached via polymer chains to favour their accumulation in diseased tissue. Polymers within protein cages offer the possibility of increasing the loading density of drug molecules, nucleic acids, magnetic resonance imaging contrast agents or catalysts. Moreover, the interaction of protein cages and polymers can be used to modulate the size and shape of some viral capsids to generate structures that do not occur with native viruses. Another possibility is to use the interior of polymer cages as a confined reaction space for polymerization reactions such as atom transfer radical polymerization or rhodium-catalysed polymerization of phenylacetylene. The protein nanoreactors facilitate a higher degree of control over polymer synthesis. This review will summarize the hybrid structures that have been synthesized by polymerizing from protein cage-bound initiators, by conjugating polymers to protein cages, by embedding protein cages into bulk polymeric

  6. Control of protein-binding kinetics on synthetic polymer nanoparticles by tuning flexibility and inducing conformation changes of polymer chains.

    Science.gov (United States)

    Hoshino, Yu; Nakamoto, Masahiko; Miura, Yoshiko

    2012-09-19

    Although a number of procedures to create synthetic polymer nanoparticles (NPs) with an intrinsic affinity to target biomacromolecules have been published, little has been reported on strategies to control the binding kinetics of target recognition. Here, we report an enzyme-mimic strategy to control binding/dissociation rate constants of NPs, which bind proteins through multipoint interactions, by taking advantage of the temperature-responsive coil-globule phase transition of poly-N-isopropylacrylamide (PNIPAm)-based NPs. PNIPAm NPs with a "flexible" random-coil conformation had a faster binding rate than NPs with a "rigid" globule conformation; however, the dissociation rate constant remained unchanged, resulting in stronger affinity. The dissociation rate of the "flexible" NPs was decelerated by the "induced-fit"-type conformation change of polymers around the coil-globule phase transition temperature, resulting in the formation of the most stable NP-protein complexes. These results provide a guide for designing plastic antibodies with tailor-made binding kinetics and equilibrium constants.

  7. Influence of natural humic acids and synthetic phenolic polymers on fibrinolysis

    Science.gov (United States)

    Klöcking, Hans-Peter

    The influence of synthetic and natural phenolic polymers on the release of plasminogen activator was studied in an isolated, perfused, vascular preparation (pig ear). Of the tested synthetic phenolic polymers, the oxidation products of caffeic acid (KOP) and 3,4-dihydroxyphenylacetic acid (3,4-DHPOP), at a concentration of 50 µg/ml perfusate, were able to increase the plasminogen activator activity by 70%. The oxidation products of chlorogenic acid (CHOP), hydrocaffeic acid (HYKOP), pyrogallol (PYROP) and gallic acid (GALOP), at the same concentration, exerted no influence on the release of plasminogen activator. Of the naturally occurring humic acids, the influence of sodium humate was within the same order of magnitude as KOP and 3,4-DHPOP. Ammonium humate was able to increase the plasminogen activator release only at a concentration of 100 µg/ml perfusate. In rats, the t-PA activity increased after i.v. application of 10 mg/kg of KOP, Na-HS or NH4-HS.

  8. Large accumulation of micro-sized synthetic polymer particles in the sea surface microlayer.

    Science.gov (United States)

    Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Kang, Jung-Hoon; Kwon, Oh Youn; Han, Gi Myung; Shim, Won Joon

    2014-08-19

    Determining the exact abundance of microplastics on the sea surface can be susceptible to the sampling method used. The sea surface microlayer (SML) can accumulate light plastic particles, but this has not yet been sampled. The abundance of microplastics in the SML was evaluated off the southern coast of Korea. The SML sampling method was then compared to bulk surface water filtering, a hand net (50 μm mesh), and a Manta trawl net (330 μm mesh). The mean abundances were in the order of SML water > hand net > bulk water > Manta trawl net. Fourier transform infrared spectroscopy (FTIR) identified that alkyds and poly(acrylate/styrene) accounted for 81 and 11%, respectively, of the total polymer content of the SML samples. These polymers originated from paints and the fiber-reinforced plastic (FRP) matrix used on ships. Synthetic polymers from ship coatings should be considered to be a source of microplastics. Selecting a suitable sampling method is crucial for evaluating microplastic pollution.

  9. Multiple Gas-Phase Conformations of a Synthetic Linear Poly(acrylamide) Polymer Observed Using Ion Mobility-Mass Spectrometry

    Science.gov (United States)

    Haler, Jean R. N.; Far, Johann; Aqil, Abdelhafid; Claereboudt, Jan; Tomczyk, Nick; Giles, Kevin; Jérôme, Christine; De Pauw, Edwin

    2017-08-01

    Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,…). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths. A unique collision cross-section (CCS) trend is usually observed when increasing the degree of polymerization (DP) at constant charge state, allowing the deciphering of different polymer topologies. In this paper, we report multiple coexisting CCS trends when increasing the DP at constant charge state for linear poly(acrylamide) PAAm in the gas phase. This is similar to observations on peptides and proteins. Biomolecules show in addition population changes when collisionally heating the ions. In the case of synthetic PAAm, fragmentation occurred before reaching the energy for conformation conversion. These observations, which were made on two different IM-MS instruments (SYNAPT G2 HDMS and high resolution multi-pass cyclic T-Wave prototype from Waters), limit the use of ion mobility for synthetic polymer topology interpretations to polymers where unique CCS values are observed for each DP at constant charge state. [Figure not available: see fulltext.

  10. A Comparison of Degradable Synthetic Polymer Fibers for Anterior Cruciate Ligament Reconstruction

    Science.gov (United States)

    Tovar, Nick; Bourke, Sharon; Jaffe, Michael; Murthy, N. Sanjeeva; Kohn, Joachim; Gatt, Charles; Dunn, Michael G.

    2009-01-01

    We compared mechanical properties, degradation rates, and cellular compatibilities of two synthetic polymer fibers potentially useful as ACL reconstruction scaffolds: poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate)(12,10), p(DTD DD) and poly(L-lactic acid), PLLA. The yield stress of ethylene oxide (ETO) sterilized wet fibers was 150 ± 22 MPa and 87 ± 12 MPa for p(DTD DD) and PLLA, respectively, with moduli of 1.7 ± 0.1 MPa and 4.4 ± 0.43 MPa. Strength and molecular weight retention were determined after incubation under physiological conditions at varying times. After 64 weeks strength decreased to 20 and 37% of the initial sterile fiber values and MW decreased to 41% and 36% of the initial values for p(DTD DD) and PLLA, respectively. ETO sterilization had no significant effect on mechanical properties. Differences in mechanical behavior may be due to the semicrystalline nature of PLLA and the small degree of crystallinity induced by mesogenic ordering in p(DTD DD) suggested by DSC analysis. Fibroblast growth was similar on 50-fiber scaffolds of both polymers through 16 days in vitro. These data suggest that p(DTD DD) fibers, with higher strength, lower stiffness, favorable degradation rate and cellular compatibility, may be a superior alternative to PLLA fibers for development of ACL reconstruction scaffolds. PMID:19623532

  11. Adhesion between biodegradable polymers and hydroxyapatite: Relevance to synthetic bone-like materials and tissue engineering scaffolds.

    Science.gov (United States)

    Neuendorf, R E; Saiz, E; Tomsia, A P; Ritchie, R O

    2008-09-01

    Many studies are currently underway on the quest to make synthetic bone-like materials with composites of polymeric materials and hydroxyapatite (HA). In the present work, we use wetting experiments and surface tension measurements to determine the work of adhesion between biodegradable polymers and HA, with specific reference to the role of humid environments. All the polymers are found to exhibit low contact angles (polymer-HA bonds, scale directly with the results from the wetting experiments. Short-time aging (up to 30h) in a humid environment, however, has a dramatic influence on such HA/polymer interfacial strengths; specifically, water diffusion through the organic/inorganic interface and degradation of the polymer results in a marked decrease, by some 80-90%, in the bond strengths. These results cast doubt on the use of biodegradable polymers/ceramic composites for load-bearing synthetic bone-like materials, as desired optimal mechanical properties are unlikely to be met in realistic physiological environments.

  12. Infection prevention using affinity polymer-coated, synthetic meshes in a pig hernia model.

    Science.gov (United States)

    Blatnik, Jeffrey A; Thatiparti, Thimma R; Krpata, David M; Zuckerman, Sean T; Rosen, Michael J; von Recum, Horst A

    2017-11-01

    Given concern for hernia mesh infection, surgeons often use biologic mesh which may provide reduced risk of infection but at the cost of decreased repair durability. We evaluated mesh coating to provide sustained release of antibiotics to prevent prosthetic mesh infection and also allow a durable repair. Cyclodextrin-based polymer was crosslinked onto multifilament polyester mesh and loaded with vancomycin (1.75 mg/cm(2)). Pigs received modified meshes (n = 6) or normal, untreated meshes (n = 4), which were implanted into acute 10 × 5 cm ventral hernia, then directly inoculated with 10(6) colony-forming unit (CFU) of methicillin-resistant Staphylococcus aureus (MRSA). These were compared to animals receiving normal, uninfected mesh. All mesh was secured in an underlay bridge manner, and after 30 d, the abdominal wall was removed for quantitative bacterial culture and biomechanical analysis. All animals survived 30 d. All six animals with coated mesh cleared MRSA infection. The four control animals did not clear MRSA (P = 0.005). Quantitative bacterial load was higher in standard mesh versus drug-delivery mesh group (2.34 × 10(4)versus 80.9 CFU/gm). These data were log10-transformed and analyzed by Welch's t-test (P = 0.001). Minimum number of CFUs detectable by assay (300) was used instead of zero. Biomechanical analysis of controls (1.82 N/mm infected; 1.71 N/mm uninfected) showed no difference to the modified meshes (1.31 N/mm) in tissue integration (P = 0.15). We successfully prevented synthetic mesh infection in a pig model using a cyclodextrin-based polymer to locally deliver vancomycin to the hernia repair site and clearing antibiotic-resistant bacteria. Polymer coating did not impact the strength of the hernia repair. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Synthetic

    Directory of Open Access Journals (Sweden)

    Anna Maria Manferdini

    2010-06-01

    Full Text Available Traditionally materials have been associated with a series of physical properties that can be used as inputs to production and manufacturing. Recently we witnessed an interest in materials considered not only as ‘true matter’, but also as new breeds where geometry, texture, tooling and finish are able to provoke new sensations when they are applied to a substance. These artificial materials can be described as synthetic because they are the outcome of various qualities that are not necessarily true to the original matter, but they are the combination of two or more parts, whether by design or by natural processes. The aim of this paper is to investigate the potential of architectural surfaces to produce effects through the invention of new breeds of artificial matter, using micro-scale details derived from Nature as an inspiration.

  14. [The Use of Synthetic Polymers (Superdisintegrants) in Technology Tablets Containing Ethanol Dry Extract from Asparagus officinalis].

    Science.gov (United States)

    Linka, Wojciech Andrzej; Wojtaszek, Ilona; Zgoda, Marian Mikołaj; Kołodziejczyk, Michał Krzysztof

    2015-01-01

    Dry extracts are now frequently used in medicine as an alternative to synthetic drugs. In the case of tablet technology with dry plant extracts, the proper selection of disintegrants (superdisintegrants) is particularly important. Objectives. The aim of this study was to evaluate the usefulness of the polymers constituting superdisintegrants (Vivasol®, Vivastar®, Polyplasdone XL) in uncoated tablet formulation of alcoholic extracted from Asparagus officinalis. Dry the ethanol extract of Asparagus officinalis, Vivasol®, Vivastar®, Vivapur®, Kollidon VA64, Polyplasdone XL, magnesium stearate. Direct compression. Paddle method was carried out to study pharmacopoeial parameters and pharmaceutical availability. The calculation of equivalency factors: similarity [f2] and the difference [f1]. Approximation results. Tablets brownish-green, with a smooth and uniform surface, without stains, chipping and damage. The determined average weight of the tablets compiled with the standards. The test friability and crushing strength revealed that the most mechanically strong tablets contained Vivasol, Vivastar, Polyplasdone XL. These tablets also have a longer disintegration and dissolution time compared with tablets containing only Vivasol. These differences are also confirmed by the calculated f2 and f1. The addition of a mixture of Polyplasdone XL and Vivastar to Vivasol significantly increases the mechanical strength of the tablets (crushing strength, resistance to crushing). The addition of a mixture of Polyplasdone XL and Vivastar to Vivasol paradoxically increases the disintegration time of tablets (11.1 min). Single superdisintegrant breaks up the tablet more effectively than a mixture of superdisintegrants.

  15. Laccase-Mediated Grafting on Biopolymers and Synthetic Polymers: A Critical Review.

    Science.gov (United States)

    Slagman, Sjoerd; Zuilhof, Han; Franssen, Maurice C R

    2017-11-07

    Laccase-mediated grafting on lignocelluloses has gained considerable attention as an environmentally benign method to covalently modify wood, paper and cork. In recent decades this technique has also been employed to modify fibres with a polysaccharide backbone, such as cellulose or chitosan, to infer colouration, antimicrobial activity or antioxidant activity to the material. The scope of this approach has been further widened by researchers, who apply mediators or high redox potential laccases and those that modify synthetic polymers and proteins. In all cases, the methodology relies on one- or two-electron oxidation of the surface functional groups or of the graftable molecule in solution. However, similar results can very often be achieved through simple deposition, even after extensive washing. This unintended adsorption of the active substance could have an adverse effect on the durability of the applied coating. Differentiating between actual covalent binding and adsorption is therefore essential, but proves to be challenging. This review not only covers excellent research on the topic of laccase-mediated grafting over the last five to ten years, but also provides a critical comparison to highlight either the lack or presence of compelling evidence for covalent grafting. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  16. Size exclusion chromatography of synthetic polymers and biopolymers on common reversed phase and hydrophilic interaction chromatography columns.

    Science.gov (United States)

    Caltabiano, Anna M; Foley, Joe P; Barth, Howard G

    2016-03-11

    This work describes the applicability of common reversed phase and HILIC columns for size exclusion chromatography of synthetic and natural polymers. Depending on the nature of the solute and column stationary phase, a "non-retention" condition must be created with the aid of the mobile phase to achieve a unique size-based separation in isocratic mode. The various bonded phases show remarkable differences in size separations that are controlled by mobile phase conditions. Polymer-mobile phase and column-mobile phase solvation interactions determine polymer hydrodynamic volume (or solute bulkiness) and polymer-column steric interaction. Solvation interactions in turn depend on polymer, mobile phase and stationary phase polarities. Column-mobile phase solvation interactions determine the structural order of the bonded ligands that can vary from ordered (extended, aligned away from the silica substrate) to disordered (folded, pointing toward the silica substrate). Chain order increases with increased solvent penetration into the bonded phase. Increased chain order reduces pore volume, and therefore decreases the size-separation efficiency of a column. Conversely, decreased chain order increases pore volume and therefore increases the size-separation efficiency. The thermodynamic quality of the mobile phase also plays a significant role in the separation of polymers. "Poor" solvents can significantly reduce the hydrodynamic diameter of a solute and thus change their retention behavior. Medium polarity stationary phases, such as fluoro-phenyl and cyano, exhibit a unique retention behavior. With an appropriate polarity mobile phase, polar and non-polar synthetic polymers of the same molecular masses can be eluted at the same retention volumes. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Prompt response and durability of polymer ablation from synthetic fibers irradiated by thermal plasmas for arc resistant clothes

    Science.gov (United States)

    Ishida, Masahiro; Shinsei, Naoki; Tanaka, Yasunori; Uesugi, Yoshihiko; Ishijima, Tatsuo; Mio, Wataru; Hagi, Hiroyasu; Uchibori, Keita

    2013-06-01

    Interactions between thermal plasmas and synthetic fibers such as polyamide, polyester, phenol and aramid were investigated by thermal plasma irradiation technique. Understanding the above interactions is crucial to design effective flame retardant synthetic fiber clothes with arc resistance to protect a human from arc flash accidents. To investigate the interactions, an Ar inductively coupled thermal plasma (ICTP) was used instead of the arc discharge because the ICTP has high controllability and no contamination. The ICTP irradiation raises polymer ablation in case of polyamide and polyester. Two features of the polymer ablation such as prompt response and durability were fundamentally investigated from viewpoint of shielding the heat flux. It was found that polyamide fiber has both a high prompt response and a long durability.

  18. Natural-Synthetic Hybrid Polymers Developed via Electrospinning: The Effect of PET in Chitosan/Starch System

    Directory of Open Access Journals (Sweden)

    Carlos Velasco-Santos

    2011-03-01

    Full Text Available Chitosan is an amino polysaccharide found in nature, which is biodegradable, nontoxic and biocompatible. It has versatile features and can be used in a variety of applications including films, packaging, and also in medical surgery. Recently a possibility to diversify chitosan properties has emerged by combining it with synthetic materials to produce novel natural-synthetic hybrid polymers. We have studied structural and thermophysical properties of chitosan + starch + poly(ethylene terephthalate (Ch + S + PET fibers developed via electrospinning. Properties of these hybrids polymers are compared with extant chitosan containing hybrids synthesized by electrospinning. Molecular interactions and orientation in the fibers are analyzed by infrared and Raman spectroscopies respectively, morphology by scanning electron microscopy and thermophysical properties by thermogravimetric analysis and differential scanning calorimetry. Addition of PET to Ch + S systems results in improved thermal stability at elevated temperatures.

  19. Natural-Synthetic Hybrid Polymers Developed via Electrospinning: The Effect of PET in Chitosan/Starch System

    Science.gov (United States)

    Espíndola-González, Adolfo; Martínez-Hernández, Ana Laura; Fernández-Escobar, Francisco; Castaño, Victor Manuel; Brostow, Witold; Datashvili, Tea; Velasco-Santos, Carlos

    2011-01-01

    Chitosan is an amino polysaccharide found in nature, which is biodegradable, nontoxic and biocompatible. It has versatile features and can be used in a variety of applications including films, packaging, and also in medical surgery. Recently a possibility to diversify chitosan properties has emerged by combining it with synthetic materials to produce novel natural-synthetic hybrid polymers. We have studied structural and thermophysical properties of chitosan + starch + poly(ethylene terephthalate) (Ch + S + PET) fibers developed via electrospinning. Properties of these hybrids polymers are compared with extant chitosan containing hybrids synthesized by electrospinning. Molecular interactions and orientation in the fibers are analyzed by infrared and Raman spectroscopies respectively, morphology by scanning electron microscopy and thermophysical properties by thermogravimetric analysis and differential scanning calorimetry. Addition of PET to Ch + S systems results in improved thermal stability at elevated temperatures. PMID:21673930

  20. Fabrication of synthetic polymer coatings and their use in feeder-free culture of human embryonic stem cells

    OpenAIRE

    Nandivada, Himabindu; Villa-Diaz, Luis G; O'Shea, K. Sue; Smith, Gary D.; Krebsbach, Paul H.; Lahann, Joerg

    2011-01-01

    The culture of human embryonic stem (hES) cells in defined and xenogeneic-free conditions will contribute substantially to future biotechnological and medical applications. To achieve this goal, we developed the first fully defined synthetic polymer coating poly[2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide] (PMEDSAH) that sustains long-term growth of hES cells in different culture media. Here we describe a detailed protocol for the reproducible fabrication of PMEDSAH co...

  1. Activity and Safety of Synthetic Lectins Based on Benzoboroxole-Functionalized Polymers for Inhibition of HIV Entry

    Science.gov (United States)

    Mahalingam, Alamelu; Geonnotti, Anthony R.; Balzarini, Jan; Kiser, Patrick F.

    2011-01-01

    Lectins derived from plant and microbial sources constitute a vital class of entry inhibitors that target the oligomannose residues on the HIV envelope gp120. Despite their potency and specificity, success of lectin-based entry inhibitors may be impeded by issues in regards to economical production, formulation and potential mitogenicity. Therefore, there exists a gap in the HIV therapeutics pipeline that underscores the need for mass producible, synthetic, broad-spectrum, and biocomptabile inhibitors of HIV entry. Here, we present the development of a polymeric synthetic lectin, based on benzoboroxole (BzB), which exhibits weak affinity (~25 M−1) for non-reducing sugars, similar to those found on the HIV envelope. High molecular weight BzB-functionalized polymers demonstrated antiviral activity that increased with an increase in ligand density and molecular weight of the polymer construct; revealing that polyvalency improves activity. Polymers showed significant increase in activity from 25 to 75 mol% BzB functionalization with EC50 of 15 μM and 15 nM, respectively. A further increase in mole functionalization to 90% resulted in an increase of the EC50 (59 ± 5 nM), likely due to the elongated rigid structure of the polymer chain compelled by electrostatic repulsion between the boronic acid groups. An increase in molecular weight of the polymer at 50 mol% BzB functionalization showed a gradual but significant increase in antiviral activity, with the highest activity seen with the 382 kDa polymer (EC50 of 1.1 ± 0.5 nM in CEM cells and 11 ± 3 nM in TZM-bl cells). Supplementing the polymer backbone with 10 mol% sulfonic acid not only increased the aqueous solubility of the polymers by at least 50-fold, but also demonstrated a synergistic increase in anti-HIV activity (4.0 ± 1.5 nM in TZM-bl cells), possibly due to electrostatic interactions between the negatively charged polymer backbone and the positively charged V3-loop in the gp120. The benzoboroxole

  2. Inhibition of PrPSc formation by synthetic O-sulfated glycopyranosides and their polymers.

    Science.gov (United States)

    Yamaguchi, Satoko; Nishida, Yoshihiro; Sasaki, Kenji; Kambara, Mikie; Kim, Chan-Lan; Ishiguro, Naotaka; Nagatsuka, Takehiro; Uzawa, Hirotaka; Horiuchi, Motohiro

    2006-10-20

    Sulfated glycosaminoglycans (GAGs) and sulfated glycans inhibit formation of the abnormal isoform of prion protein (PrPSc) in prion-infected cells and prolong the incubation time of scrapie-infected animals. Sulfation of GAGs is not tightly regulated and possible sites of sulfation are randomly modified, which complicates elucidation of the fundamental structures of GAGs that mediate the inhibition of PrPSc formation. To address the structure-activity relationship of GAGs in the inhibition of PrPSc formation, we screened the ability of various regioselectively O-sulfated glycopyranosides to inhibit PrPSc formation in prion-infected cells. Among the glycopyranosides and their polymers examined, monomeric 4-sulfo-N-acetyl-glucosamine (4SGN), and two glycopolymers, poly-4SGN and poly-6-sulfo-N-acetyl-glucosamine (poly-6SGN), inhibited PrPSc formation with 50% effective doses below 20 microg/ml, and their inhibitory effect became more evident with consecutive treatments. Structural comparisons suggested that a combination of an N-acetyl group at C-2 and an O-sulfate group at either O-4 or O-6 on glucopyranoside might be involved in the inhibition of PrPSc formation. Furthermore, polymeric but not monomeric 6SGN inhibited PrPSc formation, suggesting the importance of a polyvalent configuration in its effect. These results indicate that the synthetic sulfated glycosides are useful not only for the analysis of structure-activity relationship of GAGs but also for the development of therapeutics for prion diseases.

  3. Engineering microbial physiology with synthetic polymers: cationic polymers induce biofilm formation in Vibrio cholerae and downregulate the expression of virulence genes.

    Science.gov (United States)

    Perez-Soto, Nicolas; Moule, Lauren; Crisan, Daniel N; Insua, Ignacio; Taylor-Smith, Leanne M; Voelz, Kerstin; Fernandez-Trillo, Francisco; Krachler, Anne Marie

    2017-08-01

    Here we report the first application of non-bactericidal synthetic polymers to modulate the physiology of a bacterial pathogen. Poly(N-[3-(dimethylamino)propyl] methacrylamide) (P1) and poly(N-(3-aminopropyl)methacrylamide) (P2), cationic polymers that bind to the surface of V. cholerae, the infectious agent causing cholera disease, can sequester the pathogen into clusters. Upon clustering, V. cholerae transitions to a sessile lifestyle, characterised by increased biofilm production and the repression of key virulence factors such as the cholera toxin (CTX). Moreover, clustering the pathogen results in the minimisation of adherence and toxicity to intestinal epithelial cells. Our results suggest that the reduction in toxicity is associated with the reduction to the number of free bacteria, but also the downregulation of toxin production. Finally we demonstrate that these polymers can reduce colonisation of zebrafish larvae upon ingestion of water contaminated with V. cholerae. Overall, our results suggest that the physiology of this pathogen can be modulated without the need to genetically manipulate the microorganism and that this modulation is an off-target effect that results from the intrinsic ability of the pathogen to sense and adapt to its environment. We believe these findings pave the way towards a better understanding of the interactions between pathogenic bacteria and polymeric materials and will underpin the development of novel antimicrobial polymers.

  4. Natural and synthetics nanomaterials: comparative study on their mechanical and thermal properties as nanofiller in polymer composite

    Science.gov (United States)

    Ghaemi, Ferial; Chuah Abdullah, Luqman; Tahir, Paridah Md

    2017-10-01

    In this research, natural nanomaterials including cellulose nanocrystal (CNC) and nanofiber cellulose (NFC) and synthetic nanomaterials such as carbon nanofiber (CNF) and carbon nanotube (CNT) with different structures, sizes and surface areas were produced and analyzed. CNC and NFC were fabricated by use of acid hydrolysing and mechanical methods, respectively and synthetics nanomaterials were produced by chemical vapor deposition method (CVD). Here, in order to evaluate the effect of these nanomaterials on the mechanical and thermal properties of the polymer, use them as nanofiller in the polymer matrix. The most important challenge in this study is to evaluate and compare these nanofibers based on the effects of their structures and compositions on the mechanical and thermal properties. The characteristics of these nanofibers such as morphology, structure, and composition and also the properties of these nanomaterials including thermal stability and mechanical strength were investigated, comprehensively. Based on the results, CNT with high thermals stability and strong structure has the best filler for using in polymer composite.

  5. [A water-soluble synthetic polymer, alpha,beta-poly(hydroxyalkyl)-DL-asparamide, and conjugating drug].

    Science.gov (United States)

    Zhang, Z; Tang, G; Chen, Q; Wang, B; Ma, M; Zhang, X

    1999-12-01

    A water-soluble polymer alpha,beta-poly (hydroxyalkyl)-DL-asparamide was synthesized by polysuccinimide(PSI) and different lengths of hydroxyalkyls, including alpha,beta-poly(hydroxyethyl)-DL-asparamide(PHEA), alpha,beta-poly(hydroxypropyl)-DL-asparamide(PHPA), and alpha,beta-poly(hydroxybutyl)-DL-asparamide(PHBA). These polymers were characterized by differential scanning calorimetry(DSC) and infrared spectrophotometry(IR). Stability and acutetoxicity of these polymers were studied. The experiment indicated that these materials were of low-toxicity and high stability. Acetylsalicylic acid, as a model drug, was conjugated into polymers; the drug loadings were 38.63%, 37.68% and 38.70% respectively. Polymer drugs were made into cylinder, and in-vivo release in rabbits was set out. It showed that the longer the spacer was linked into the polymer, the faster the drug was released.

  6. Enzymatic modification of natural and synthetic polymers using lipases and proteases

    Science.gov (United States)

    Chakraborty, Soma

    Enzymatic modification of natural/synthetic polymers [starch nanoparticles, poly (n-alkyl acrylates) and poly(vinyl formamide)] was studied. Enzymes used for catalysis were lipases and proteases. Starch nanoparticles (40nm diameter) were incorporated into AOT-coated reverse micelles. Reactions performed with the acylating agents vinyl stearate, epsilon-caprolactone and maleic anhydride in toluene in presence of Novozyme-435 at 40°C for 36h gave products with degrees of substitution of 0.8, 0.6 and 0.4 respectively. DEPT-135 NMR spectra revealed that the modification occurred regioselectively at the C-6 position of the glucose units. Infrared microspectroscopy showed that the surfactant coated starch nanoparticles diffuse into pores of Novozyme-435 beads, coming in close proximity with CALB to promote modification. The modified products retained nanoscale dimensions. Catalysis of amide bond formation between a low molar mass amine and ester side groups of poly(n-alkyl acrylates)[poly(ethyl acrylate), poly(methyl acrylate) and poly(butyl acrylate)] was also examined. The nucleophiles were mono and diamines. Among the poly(n-alkyl acrylates) and the lipases studied, poly(ethyl acrylate) was the preferred substrate and Novozyme-435 the most active lipase. Poly(ethyl acrylate) in 80% by-volume toluene was reacted with 1 equivalent per repeat unit of hexyl amine at 70°C in presence of Novozyme-435. The product contained 10.6 mol% amide groups. Attempts to increase the amidation beyond 10--11 mol% by increasing the reaction time or use of fresh enzyme were unsuccessful, showing that poly(ethylacrylate-co-10mol%hexylacrylamide) is a poor substrate for further acylation. When chiral amines ([R,S]-alpha-methyl benzylamine, [R,S]-beta-methyl phenyl amine) were used as nucleophiles, Novozyme-435 enantioselectively catalyzed amidation of poly(ethyl acrylate). Poly(vinyl formamide), P(VfAm) by acid or base-catalyzed hydrolysis leads to poly(vinylamine), P(VAm), and

  7. Magnetic molecularly imprinted polymers synthesized by surface-initiated reversible addition-fragmentation chain transfer polymerization for the enrichment and determination of synthetic estrogens in aqueous solution.

    Science.gov (United States)

    Chen, Fangfang; Zhang, Jingjing; Wang, Minjun; Kong, Jie

    2015-08-01

    Magnetic molecularly imprinted polymers have attracted significant interest because of their multifunctionality of selective recognition of target molecules and rapid magnetic response. In this contribution, magnetic molecularly imprinted polymers were synthesized via surface-initiated reversible addition addition-fragmentation chain transfer polymerization using diethylstilbestrol as the template for the enrichment of synthetic estrogens. The uniform imprinted surface layer and the magnetic property of the magnetic molecularly imprinted polymers favored a fast binding kinetics and rapid analysis of target molecules. The static and selective binding experiments demonstrated a desirable adsorption capacity and good selectivity of the magnetic molecularly imprinted polymers in comparison to magnetic non-molecularly imprinted polymers. Accordingly, a corresponding analytical method was developed in which magnetic molecularly imprinted polymers were employed as magnetic solid-phase extraction materials for the concentration and determination of four synthetic estrogens (diethylstilbestrol, hexestrol, dienestrol, and bisphenol A) in fish pond water. The recoveries of these synthetic estrogens in spiked fish pond water samples ranged from 61.2 to 99.1% with a relative standard deviation of lower than 6.3%. This study provides a versatile approach to prepare well-defined magnetic molecularly imprinted polymers sorbents for the analysis of synthetic estrogens in water solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Effect of surfactant species and electrophoretic medium composition on the electrophoretic behavior of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis.

    Science.gov (United States)

    Fukai, Nao; Kitagawa, Shinya; Ohtani, Hajime

    2017-07-01

    We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation. The order of the interaction between the polymers and the surfactants depended on both the surfactant species and the composition of the electrophoretic medium. Their investigation revealed that the separation is majorly affected by the hydrophobic interactions between the polymers and the ionic surfactants. In addition, the electrophoretic behavior of polycarbonate suggested that electrostatic interaction also affects the selectivity of the polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Synthetic polymers in the marine environment: a rapidly increasing, long-term threat.

    Science.gov (United States)

    Moore, Charles James

    2008-10-01

    Synthetic polymers, commonly known as plastics, have been entering the marine environment in quantities paralleling their level of production over the last half century. However, in the last two decades of the 20th Century, the deposition rate accelerated past the rate of production, and plastics are now one of the most common and persistent pollutants in ocean waters and beaches worldwide. Thirty years ago the prevailing attitude of the plastic industry was that "plastic litter is a very small proportion of all litter and causes no harm to the environment except as an eyesore" [Derraik, J.G.B., 2002. The pollution of the marine environment by plastic debris: a review. Mar. Pollut. Bull. 44(9), 842-852]. Between 1960 and 2000, the world production of plastic resins increased 25-fold, while recovery of the material remained below 5%. Between 1970 and 2003, plastics became the fastest growing segment of the US municipal waste stream, increasing nine-fold, and marine litter is now 60-80% plastic, reaching 90-95% in some areas. While undoubtedly still an eyesore, plastic debris today is having significant harmful effects on marine biota. Albatross, fulmars, shearwaters and petrels mistake floating plastics for food, and many individuals of these species are affected; in fact, 44% of all seabird species are known to ingest plastic. Sea turtles ingest plastic bags, fishing line and other plastics, as do 26 species of cetaceans. In all, 267 species of marine organisms worldwide are known to have been affected by plastic debris, a number that will increase as smaller organisms are assessed. The number of fish, birds, and mammals that succumb each year to derelict fishing nets and lines in which they become entangled cannot be reliably known; but estimates are in the millions. We divide marine plastic debris into two categories: macro, >5 mm and micro, plastic micro-debris by filter feeders at the base of the food web is known to occur, but has not been quantified

  10. Molecularly imprinted polymers as synthetic mimics of bioreceptors. 1. General principles of molecular imprinting

    Directory of Open Access Journals (Sweden)

    Sergeyeva T. A.

    2009-08-01

    Full Text Available The review is devoted to analysis of the publications in the area of synthesis of artificial mimics of biological receptors using the method of molecular imprinting. General principles of molecular imprinting as well as main types of polymers being used in molecular imprinting are described. The special attention is paid to the polymers-biomimics synthesized using the method of non-covalent molecular imprinting.

  11. Biodegradable Polymers

    OpenAIRE

    Isabelle Vroman; Lan Tighzert

    2013-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  12. Novel thermoresponsive assemblies of co-grafted natural and synthetic polymers for water purification.

    Science.gov (United States)

    Paneysar, Joginder Singh; Barton, Stephen; Chandra, Sudeshna; Ambre, Premlata; Coutinho, Evans

    2017-03-01

    Water contamination and its purification are a global problem. The current approach to purify water is reduction of impurities to acceptable levels. One of the ways to achieve this is by use of water-soluble polymers that extract organic and metallic contaminants, from water. This paper presents a blend of composite polymers that eliminates both the contaminants simultaneously by the principle of adsorption at lower critical solution temperature. These composite polymers have been synthesized by grafting poly(N,N-diethylacrylamide), poly(N-isopropylacrylamide) and poly(N-vinylcaprolactam) on-to the natural polymer chitosan or its derivatives, giving smart graft polymeric assemblies (GPAs). One of the graft polymers, GPA-2, exhibits excellent adsorption properties able to remove metal ions like cadmium, cobalt, copper, lead, iron and also organic impurities like chlorophenol and phthalic anhydride. Studies reveal that 6 mg/ml GPA-2 is able to effect a 100% removal of organic impurities - chlorophenol (50 ppm) and phthalic anhydride (70 ppm) - from water, while complete removal of the heavy metal ions (Cu+2, Co+2 and Cd+2) together at 30 ppm concentration has been achieved with 7.5 mg/ml GPA-2. The reduction in level of impurities along with recyclability and reproducibility in the elimination spectrum makes these assemblies promising materials in water treatment.

  13. Synthetic/Biosynthetic Phase Transfer Polymers for Pollution Minimization, Remediation, and Waste Management

    Science.gov (United States)

    1994-01-01

    polymer and model pollutant separation and recovery 7) Contribution to the interdisciplinary research and education of young scientists in biological...N&. 8. 14 NN2 Figure 1. 8trocturs of AWIDAMAB IopolyinRs interaction o rmtydoeyamnu bromide with *olyVsTyrnslOna. and dextrmn sulfate. 7he squi - too

  14. Copyrolysis of wood biomass and synthetic polymers mixtures. Part 2. Characterisation of the liquid phases

    Energy Technology Data Exchange (ETDEWEB)

    Marin, N.; Collura, S.; Weber, J.V. [Laboratoire de Chimie et Applications, Universite de Metz, IUT, rue Victor Demange, 57500 Saint Avold (France); Sharypov, V.I.; Beregovtsova, N.G.; Baryshnikov, S.V.; Kutnetzov, B.N. [Institute of Chemistry and Chemical Technology SB RAS, Academgorodok, 660049 Krasnoyarsk (Russia); Cebolla, V. [Instituto de Carboquimica, CSIC, Zaragoza (Spain)

    2002-10-01

    The copyrolysis of wood biomass-polyolefins was carried out in a rotating autoclave. At 400C, more than 50% (in mass) of final products are found in the liquid phase for a 1:1 (in mass) mixture. The obtained liquids are separated in a distillable liquids fraction and in an extracted liquids fraction. The first fraction can be fully characterised by gas chromatography/mass spectrometry. Only olefins, paraffins and some aromatics (benzene, toluene and xylene), issued from the polymers, are found in this fraction. The origin of the polymer plays the most important role in the chemical composition of this fraction. Some interactions with the solid issued from thermal degradation of the biomass are evidenced, for example by the presence of 2-alkenes with 3n carbon atoms. In the heavy liquids fraction, more than 80% (in mass) of the products are heavy olefins or paraffins. Schematically, we can explain the results of the copyrolysis experiments by: the biomass, whatever its origin, leads to solid, water and gas; polymer leads to liquid and gaseous olefins and paraffins; at a temperature lower than 400C, the biomass reacts and during the pyrolysis at 400C the formed solid evolves to act as a radical donor; assisted by radicals from biomass, polymer chain scission leads to the production of the light liquids; if the presence of biomass has an influence on the chemical composition of final products (particularly the light liquids fraction) their origin has, in general, only a limited effect.

  15. Magnetic polymer beads: Recent trends and developments in synthetic design and applications

    KAUST Repository

    Philippova, Olga

    2011-04-01

    The paper describes the synthesis, properties and applications of magnetic polymer beads. State-of-the-art, future challenges, and promising trends in this field are analyzed. New applications in oil recovery are described. © 2010 Elsevier Ltd. All rights reserved.

  16. Co-pyrolysis of wood biomass and synthetic polymers mixtures. Part 3. Characterisation of heavy products

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, V.I.; Beregovtsova, N.G.; Kuznetsov, B.N. [Institute of Chemistry and Chemical Technology SB RAS, K. Marx str., 42, Krasnoyarsk 660049 (Russian Federation); Membrado, L.; Cebolla, V.L. [Instituto de Carboquimica, CSIC, Zaragoza (Spain); Marin, N.; Weber, J.V. [Laboratoire de Chimie et Applications, Universite de Metz, IUT, rue V. Demange, 57500 Saint-Avold (France)

    2003-05-01

    The chemical composition of heavy liquids (b.p.>180C) obtained by co-pyrolysis of polyolefins/wood biomass mixtures in autoclave conditions under inert atmosphere was investigated by FTIR, {sup 1}H NMR, GC-MS, high performance TLC combined with densitometry techniques. The preliminary separation of heavy liquids into different fractions by open LC and TLC methods had been used. Some perspectives of polymer and biomass thermal conversion during co-pyrolysis process were discussed.

  17. Preparation, Characterization and Efficacy Evaluation of Synthetic Biocompatible Polymers Linking Natural Antioxidants

    Directory of Open Access Journals (Sweden)

    Nevio Picci

    2012-10-01

    Full Text Available The purpose of this work was the synthesis, characterization and efficacy evaluation of new biocompatible antioxidant polymers linking trans-ferulic acid or a-lipoic acid. In particular, ferulic or lipoic acid were introduced in the preformed polymeric backbone. The new antioxidant biopolymers were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The degree of functionalization (moles of antioxidant per gram of polymer was determined by the Gaur-Gupta method for free amino group determination and by the Folin method for the phenolic groups. Their ability to inhibit lipid peroxidation were estimated in rat liver microsomal membranes induced in vitro by tert-BOOH (tert-butyl hydroperoxide, as a source of free radicals. The DPPH (1,1-diphenyl-2-picrylhydrazyl radical-scavenging effect was also evaluated. The obtained systems, with different solubility, showed strong antioxidant and antiradical activities, suggesting potential use as packaging materials for foods, cosmetics, pharmaceuticals and personal care products. Moreover, the cytotoxicity of the synthesized polymers was also evaluated on Caco-2 cell cultures in order to verify their biocompatibility when exposed to an absorptive epithelial cell line.

  18. Porous organic polymers with anchored aldehydes: A new platform for post-synthetic amine functionalization en route for enhanced CO2 adsorption properties

    KAUST Repository

    Guillerm, Vincent

    2014-01-01

    A novel porous organic polymer has been synthesized using the molecular building block approach to deliberately encompass aldehyde functionalities amenable to post functionalization. The resultant porous framework allows a facile, one-step quantitative and post-synthetic functionalization by amines, permitting enhanced CO2 sorption properties. © 2014 The Royal Society of Chemistry.

  19. Reverse adhesion of a gecko-inspired synthetic adhesive switched by an ion-exchange polymer-metal composite actuator.

    Science.gov (United States)

    Guo, Dong-Jie; Liu, Rui; Cheng, Yu; Zhang, Hao; Zhou, Li-Ming; Fang, Shao-Ming; Elliott, Winston Howard; Tan, Wei

    2015-03-11

    Inspired by how geckos abduct, rotate, and adduct their setal foot toes to adhere to different surfaces, we have developed an artificial muscle material called ion-exchange polymer-metal composite (IPMC), which, as a synthetic adhesive, is capable of changing its adhesion properties. The synthetic adhesive was cast from a Si template through a sticky colloid precursor of poly(methylvinylsiloxane) (PMVS). The PMVS array of setal micropillars had a high density of pillars (3.8 × 10(3) pillars/mm(2)) with a mean diameter of 3 μm and a pore thickness of 10 μm. A graphene oxide monolayer containing Ag globular nanoparticles (GO/Ag NPs) with diameters of 5-30 nm was fabricated and doped in an ion-exchanging Nafion membrane to improve its carrier transfer, water-saving, and ion-exchange capabilities, which thus enhanced the electromechanical response of IPMC. After being attached to PMVS micropillars, IPMC was actuated by square wave inputs at 1.0, 1.5, or 2.0 V to bend back and forth, driving the micropillars to actively grip or release the surface. To determine the adhesion of the micropillars, the normal adsorption and desorption forces were measured as the IPMC drives the setal micropillars to grip and release, respectively. Adhesion results demonstrated that the normal adsorption forces were 5.54-, 14.20-, and 23.13-fold higher than the normal desorption forces under 1.0, 1.5, or 2.0 V, respectively. In addition, shear adhesion or friction increased by 98, 219, and 245%, respectively. Our new technique provides advanced design strategies for reversible gecko-inspired synthetic adhesives, which might be used for spiderman-like wall-climbing devices with unprecedented performance.

  20. MS/MS-Assisted Design of Sequence-Controlled Synthetic Polymers for Improved Reading of Encoded Information

    Science.gov (United States)

    Charles, Laurence; Cavallo, Gianni; Monnier, Valérie; Oswald, Laurence; Szweda, Roza; Lutz, Jean-François

    2017-06-01

    In order to improve their MS/MS sequencing, structure of sequence-controlled synthetic polymers can be optimized based on considerations regarding their fragmentation behavior in collision-induced dissociation conditions, as demonstrated here for two digitally encoded polymer families. In poly(triazole amide)s, the main dissociation route proceeded via cleavage of the amide bond in each monomer, hence allowing the chains to be safely sequenced. However, a competitive cleavage of an ether bond in a tri(ethylene glycol) spacer placed between each coding moiety complicated MS/MS spectra while not bringing new structural information. Changing the tri(ethylene glycol) spacer to an alkyl group of the same size allowed this unwanted fragmentation pathway to be avoided, hence greatly simplifying the MS/MS reading step for such undecyl-based poly(triazole amide)s. In poly(alkoxyamine phosphodiester)s, a single dissociation pathway was achieved with repeating units containing an alkoxyamine linkage, which, by very low dissociation energy, made any other chemical bonds MS/MS-silent. Structure of these polymers was further tailored to enhance the stability of those precursor ions with a negatively charged phosphate group per monomer in order to improve their MS/MS readability. Increasing the size of both the alkyl coding moiety and the nitroxide spacer allowed sufficient distance between phosphate groups for all of them to be deprotonated simultaneously. Because the charge state of product ions increased with their polymerization degree, MS/MS spectra typically exhibited groups of fragments at one or the other side of the precursor ion depending on the original α or ω end-group they contain, allowing sequence reconstruction in a straightforward manner. [Figure not available: see fulltext.

  1. Synthetic approaches towards new polymer systems by the combination of living carbocationic and anionic polymerizations

    DEFF Research Database (Denmark)

    Feldthusen, Jesper; Ivan, Bela; Muller, Axel. H.E.

    1996-01-01

    Recent efforts to obtain block copolymers by combination of living carbocationic and anionic polymerizations are presented.When tolyl-ended polyisobutylene was used as macroinitiator of anionic polymerization of methacrylate derivatives mixtures of homopolymers and block copolymers were formed due...... to incomplete lithiation of this chain end.In another approach a new functionalization method was developed by end-quenching living polyisobutylene with 1,1-diphenylethylene. After transformation of the groups into 2,2-diphenylvinyl end groups and lithiation polymers were synthesized from protected acrylate...

  2. Surface chemical immobilization of bioactive peptides on synthetic polymers for cardiac tissue engineering.

    Science.gov (United States)

    Rosellini, Elisabetta; Cristallini, Caterina; Guerra, Giulio D; Barbani, Niccoletta

    2015-01-01

    The aim of this work was the development of new synthetic polymeric systems, functionalized by surface chemical modification with bioactive peptides, for myocardial tissue engineering. Polycaprolactone and a poly(ester-ether-ester) block copolymer synthesized in our lab, polycaprolactone-poly(ethylene oxide)-polycaprolactone (PCL-PEO-PCL), were used as the substrates to be modified. Two pentapeptides, H-Gly-Arg-Gly-Asp-Ser-OH (GRGDS) from fibronectin and H-Tyr-Ile-Gly-Ser-Arg-OH (YIGSR) from laminin, were used for the functionalization. Polymeric membranes were obtained by casting from solutions and then functionalized by means of alkaline hydrolysis and subsequent coupling of the bioactive molecules through 1-(3-dimethylaminopropyl)-3-ethylcarbodimide hydrochloride/N-hydroxysuccinimide chemistry. The hydrolysis conditions, in terms of hydrolysis time, temperature, and sodium hydroxide concentration, were optimized for the two materials. The occurrence of the coupling reaction was demonstrated by infrared spectroscopy, as the presence on the functionalized materials of the absorption peaks typical of the two peptides. The peptide surface density was determined by chromatographic analysis and the distribution was studied by infrared chemical imaging. The results showed a nearly homogeneous peptide distribution, with a density above the minimum value necessary to promote cell adhesion. Preliminary in vitro cell culture studies demonstrated that the introduction of the bioactive molecules had a positive effect on improving C2C12 myoblasts growth on the synthetic materials.

  3. Co(salen catalysed oxidation of synthetic lignin-like polymer: Co(salen effects

    Directory of Open Access Journals (Sweden)

    Liu Jing

    2012-01-01

    Full Text Available In this paper, Co(salen [salen = N, N’-bis(salicylideneethylenediamine] complex was studied as oxygen activators for the catalytic oxidation of a lignin model polymer using water as the solvent, with molecular oxygen and hydrogen peroxide as the oxidants. The effect of Co(salen on oxidation was tested by spectroscopic methods (FTIR, 13C-NMR and GC-MS. The reactions catalysed by Co(salen included Cα-alcohol oxidation, Cα-Cβ side chain cleavage, demethoxylation, aromatic ring cleavage, and β-O-4 cleavage. In addition to the mechanistic information obtained, the effect of Co(salen suggests that Co(salen can be important for the catalytic oxidation, as they affect the oxidation of lignin model polymer. The reaction performed in the presence of Co(salen was more efficient than without it. The formation of aldehyde in the catalytic oxidation, as shown by GC-MS, could be identified as the mechanism of oxidative cleavage of the β-O-4 bonds.

  4. A Comprehensive Study on Fast Dispersible and Slow-Releasing Characteristic of Orange Peel Pectin in Relation to Established Synthetic Polymer.

    Science.gov (United States)

    Srivastava, Pranati; Singh, Mahendra; Bhargava, Shilpi

    2017-10-01

    In the present work, the method to extract, isolate, and characterize orange peel pectin using soxhlation, and thereafter, the use of this polymer-polymer in the formulation of fast dispersable and slow-releasing tablet has been studied. Thereafter, the evaluation and comparison of fast dispersible/slow-releasing tablets using orange peel pectin versus prepared using sodium starch glycolate (SSG) were carried out. In the present investigation, extraction methodology was employed for isolation of pectin from orange peels. Four different batches with each polymer were prepared with varying concentration of superdisintegrant and bulking agent using diclofenac sodium as model drug. Diclofenac sodium stands as easily available, cheap, and good candidate to demonstrate disintegrant property. The formulation involved wet granulation method for the preparation of tablets of each batch. The tablets were evaluated for hardness, friability, thickness, wetting time, deaggregation time, and in vitro release characteristic data. It was observed that parameters for batch O2* were comparable with that of synthetic superdisintegrant. This batch gave around 92.12% drug release in period of 90 min. The study showed that orange peel pectin could be a potential candidate for formulation of orodispersible dosage forms in competence to SSG, which is established superdisintegrant. The results led to the conclusion that the use of natural polymers in formulation of pharmaceutical dosage form can be put into practice on industrial scale meeting the similar requirements as done by synthetic polymers. The present work aims to demonstrate and establish the use of naturally derived polymer, i.e., orange peel pectin as a superdisintegrant. The extraction methodology has been discussed followed by comparative analysis with a synthetic polymer. Abbreviations used: O1-O2: Batches Containing Orange peel pectin, S1-S2: Batches containing SSG, SSG: Sodium starch glycolate, NDDS: Novel drug delivery

  5. Dynamics of Membrane Proteins within Synthetic Polymer Membranes with Large Hydrophobic Mismatch.

    Science.gov (United States)

    Itel, Fabian; Najer, Adrian; Palivan, Cornelia G; Meier, Wolfgang

    2015-06-10

    The functioning of biological membrane proteins (MPs) within synthetic block copolymer membranes is an intriguing phenomenon that is believed to offer great potential for applications in life and medical sciences and engineering. The question why biological MPs are able to function in this completely artificial environment is still unresolved by any experimental data. Here, we have analyzed the lateral diffusion properties of different sized MPs within poly(dimethylsiloxane) (PDMS)-containing amphiphilic block copolymer membranes of membrane thicknesses between 9 and 13 nm, which results in a hydrophobic mismatch between the membrane thickness and the size of the proteins of 3.3-7.1 nm (3.5-5 times). We show that the high flexibility of PDMS, which provides membrane fluidities similar to phospholipid bilayers, is the key-factor for MP incorporation.

  6. Cryogels on the basis of natural and synthetic polymers: preparation, properties and application

    Energy Technology Data Exchange (ETDEWEB)

    Lozinsky, Vladimir I [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-06-30

    This review deals with cryotropic gelation in polymeric systems, which takes place on moderate freezing, storing in a frozen state and subsequent thawing of solutions or colloidal dispersions containing monomeric or polymeric precursors. The polymer materials formed under these conditions are termed as cryogels. They are macroporous heterophase gels in which polycrystals of the frozen solvent act as porogens during gel formation. The current knowledge about the structure of moderately frozen solutions of low- and high-molecular-mass compounds is considered, the general regularities of the cryotropic gelation processes and their similarity to and differences from gelation at positive temperatures are discussed, the fields of application of cryotropic gelation techniques are described, and examples of using polymeric cryogel-based materials for solving applied problems are given. The bibliography includes 433 references.

  7. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the “one-pot” synthetic approach of single-electron-transfer living radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang, Ke [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China); Xu, Dazhuang [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Liu, Liangji [Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine, Nanchang 330006 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2016-08-15

    Graphical abstract: The PEGylated graphene oxides with high water dispersibility, good biocompatibility as well as high drug loading capability were fabricated via “one-pot” SET-LRP. - Highlights: • Surface modification of graphene oxide with polymers. • One-pot single-electron-transfer living radical polymerization. • Improving drug delivery characteristics. • The synthetic approach is rather simple, universal and effective. - Abstract: Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient “one-pot” strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as {sup 1}H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  8. Biopolymeric Mucin and Synthetic Polymer Analogs: Their Structure, Function and Role in Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Sundar P. Authimoolam

    2016-03-01

    Full Text Available Mucin networks are viscoelastic fibrillar aggregates formed through the complex self-association of biopolymeric glycoprotein chains. The networks form a lubricious, hydrated protective shield along epithelial regions within the human body. The critical role played by mucin networks in impacting the transport properties of biofunctional molecules (e.g., biogenic molecules, probes, nanoparticles, and its effect on bioavailability are well described in the literature. An alternate perspective is provided in this paper, presenting mucin’s complex network structure, and its interdependent functional characteristics in human physiology. We highlight the recent advances that were achieved through the use of mucin in diverse areas of bioengineering applications (e.g., drug delivery, biomedical devices and tissue engineering. Mucin network formation is a highly complex process, driven by wide variety of molecular interactions, and the network possess structural and chemical variations, posing a great challenge to understand mucin’s bulk behavior. Through this review, the prospective potential of polymer based analogs to serve as mucin mimic is suggested. These analog systems, apart from functioning as an artificial model, reducing the current dependency on animal models, can aid in furthering our fundamental understanding of such complex structures.

  9. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  10. Synthetic Polymers at Interfaces: Monodisperse Emulsions Multiple Emulsions and Liquid Marbles

    Science.gov (United States)

    Sun, Guanqing

    The adsorption of polymeric materials at interfaces is an energetically favorable process which is investigated in much diversified fields, such as emulsions, bubbles, foams, liquid marbles. Pickering emulsion, which is emulsion stabilized by solid particles has been investigated for over one century and preparation of Pickering emulsion with narrow size distribution is crucial for both the theoretical study of the stabilization mechanism and practical application, such as templated fabrication of colloidosomes. The precise control over the size and functionality of polymer latices allows the preparation of monodisperse Pickering emulsions with desired sizes through SPG membrane emulsification at rather rapid rate compared to microfludic production. Double or multiple emulsions have long been investigated but its rapid destabilization has always been a major obstacle in applying them into practical applications. The modern living polymerization techniques allow us to prepare polymers with designed structure of block copolymers which makes it possible to prepare ultra-stable multiple emulsions. The precise tuning of the ratio of hydrophobic part over the hydrophilic can unveil the stabilization mechanism. Liquid marble is a new type of materials of which liquid droplets are coated by dry particles. The coating of an outer layer of dry particles renders the liquid droplets non-sticky at solid surface which is useful in transportation of small amount of liquid without leakage at extreme low friction force. The property of liquid marbles relies largely on the stabilizers and the drying condition of polymeric latices is shown to have great influence on the property of liquid marbles. Firstly, an introduction to the interfacial and colloidal science with special attention to topics on emulsions, multiple emulsion and liquid marbles is given in Chapter 1. The unique features of an interface and a discussion on the definition of colloids are introduced prior to the

  11. Surface patterning with natural and synthetic polymers via an inverse electron demand Diels-Alder reaction employing microcontact chemistry.

    Science.gov (United States)

    Roling, Oliver; Mardyukov, Artur; Lamping, Sebastian; Vonhören, Benjamin; Rinnen, Stefan; Arlinghaus, Heinrich F; Studer, Armido; Ravoo, Bart Jan

    2014-10-21

    Bioorthogonal ligation methods are the focus of current research due to their versatile applications in biotechnology and materials science for post-functionalization and immobilization of biomolecules. Recently, inverse electron demand Diels-Alder (iEDDA) reactions employing 1,2,4,5-tetrazines as electron deficient dienes emerged as powerful tools in this field. We adapted iEDDA in microcontact chemistry (μCC) in order to create enhanced surface functions. μCC is a straightforward soft-lithography technique which enables fast and large area patterning with high pattern resolutions. In this work, tetrazine functionalized surfaces were reacted with carbohydrates conjugated with norbornene or cyclooctyne acting as strained electron rich dienophiles employing μCC. It was possible to create monofunctional as well as bifunctional substrates which were specifically addressable by proteins. Furthermore we structured glass supported alkene terminated self-assembled monolayers with a tetrazine conjugated atom transfer radical polymerization (ATRP) initiator enabling surface grafted polymerizations of poly(methylacrylate) brushes. The success of the surface initiated iEDDA via μCC as well as the functionalization with natural and synthetic polymers was verified via fluorescence and optical microscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR).

  12. Heart Attack

    Science.gov (United States)

    Each year almost 800,000 Americans have a heart attack. A heart attack happens when blood flow to the heart suddenly ... it's important to know the symptoms of a heart attack and call 9-1-1 if you or ...

  13. Generation of live offspring from vitrified embryos with synthetic polymers SuperCool X-1000 and SuperCool Z-1000.

    Science.gov (United States)

    Marco-Jimenez, F; Jimenez-Trigos, E; Lavara, R; Vicente, J S

    2014-01-01

    Ice growth and recrystallisation are considered important factors in determining vitrification outcomes. Synthetic polymers inhibit ice formation during cooling or warming of the vitrification process. The aim of this study was to assess the effect of adding commercially available synthetic polymers SuperCool X-1000 and SuperCool Z-1000 to vitrification media on in vivo development competence of rabbit embryos. Four hundred and thirty morphologically normal embryos recovered at 72 h of gestation were used. The vitrification media contained 20% dimethyl sulphoxide and 20% ethylene glycol, either alone or in combination with 1% of SuperCool X-1000 and 1% SuperCool. Our results show that embryos can be successfully vitrified using SuperCool X-1000 and SuperCool Z-1000 and when embryos are transferred, live offspring can be successfully produced. In conclusion, our results demonstrated that we succeeded for the first time in obtaining live offspring after vitrification of embryos using SuperCool X-1000 and SuperCool Z-1000 polymers.

  14. Co-pyrolysis of wood biomass and synthetic polymer mixtures. Part 1. Influence of experimental conditions on the evolution of solids, liquids and gases

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, V.I.; Beregovtsova, N.G.; Baryshnikov, S.V.; Kuznetsov, B.N. [Institute of Chemistry and Chemical Technology SB RAS, 42 Karl Marx Street, Academgorodok, 660049 Krasnoyarsk (Russian Federation); Marin, N.; Weber, J.V. [Laboratoire de Chimie et Applications, Universite de Metz, IUT, Rue V. Demange, 57500 Saint-Avold (France); Cebolla, V.L. [Instituto de Carboquimica, CSIC, Zaragoza (Spain)

    2002-07-01

    The thermal behaviour of wood biomass and synthetic polymer mixtures was studied in a rotating autoclave. Beech wood, pine wood, cellulose, hydrolytic lignin, medium density polyethylene, isotactic and atactic polypropylene were selected as starting materials. The effects of reaction conditions, biomass and polymers' origins on the degree of mixture conversion as well as on the yields of liquid and gaseous products were established and discussed. A preliminary thermogravimetric investigation has shown that biomass is thermally degraded at a lower temperature than the studied polyolefins. As described in the literature, independent thermal behaviors were, in all cases, observed for each component of biomass/plastic mixtures (1:1 weight ratio). Co-pyrolysis of the different types of natural and synthetic polymer mixtures in an inert atmosphere has led to high yield of light distillate fraction and benzene soluble products. The optimum temperature for biomass/plastic mixture conversion which corresponds to the maximum yield of light liquids was 400C. The origins of both biomass and plastic had significant influences on the co-pyrolysis products' distribution. In some cases non-additive effects were observed. This effect, generally, took place at biomass/plastic ratio lower then 1 (weight ratio) and resulted in high yields of distillate liquid fraction.

  15. Application of nonpolar matrices for the analysis of low molecular weight nonpolar synthetic polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    Science.gov (United States)

    Macha; Limbach; Savickas

    2000-08-01

    The application of nonpolar matrices for the analysis of low molecular weight nonpolar synthetic polymers using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is demonstrated. Anthracene, pyrene, and acenaphthene were utilized as nonpolar matrices for the analysis of polybutadiene, polyisoprene, and polystyrene samples of various average molecular weights ranging from about 700 to 5,000. The standard MALDI-MS approach for the analysis of these types of polymers involves the use of conventional acidic matrices, such as all-trans-retinoic acid, with an additional cationization reagent. The nonpolar matrices used in this study are shown to be as equally effective as the conventional matrices. The uniform mixing of the nonpolar matrices and the nonpolar analytes enhances the MALDI-MS spectral reproducibility. Silver salts were found to be the best cationization reagents for all of the cases studied. Copper salts worked well for polystyrene, poorly for polyisoprene, and not at all for polybutadiene samples. These matrices should be useful for the characterization of hydrocarbon polymers and other analytes, such as modified polymers, which may potentially be sensitive to acidic matrices.

  16. Nanoencapsulation of Aloe vera in Synthetic and Naturally Occurring Polymers by Electrohydrodynamic Processing of Interest in Food Technology and Bioactive Packaging.

    Science.gov (United States)

    Torres-Giner, Sergio; Wilkanowicz, Sabina; Melendez-Rodriguez, Beatriz; Lagaron, Jose M

    2017-06-07

    This work originally reports on the use of electrohydrodynamic processing (EHDP) to encapsulate Aloe vera (AV, Aloe barbadensis Miller) using both synthetic polymers, i.e., polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVOH), and naturally occurring polymers, i.e., barley starch (BS), whey protein concentrate (WPC), and maltodextrin. The AV leaf juice was used as the water-based solvent for EHDP, and the resultant biopolymer solution properties were evaluated to determine their effect on the process. Morphological analysis revealed that, at the optimal processing conditions, synthetic polymers mainly produced fiber-like structures, while naturally occurring polymers generated capsules. Average sizes ranged from 100 nm to above 3 μm. As a result of their different and optimal morphology and, hence, higher AV content, PVP, in the form of nanofibers, and WPC, of nanocapsules, were further selected to study the AV stability against ultraviolet (UV) light exposure. Fourier transform infrared (FTIR) spectroscopy confirmed the successful encapsulation of AV in the biopolymer matrices, presenting both encapsulants a high chemical interaction with the bioactive components. Ultraviolet-visible (UV-vis) spectroscopy showed that, while PVP nanofibers offered a poor effect on the AV degradation during UV light exposure (∼10% of stability after 5 h), WPC nanobeads delivered excellent protection (stability of >95% after 6 h). This was ascribed to positive interactions between WPC and the hydrophilic components of AV and the inherent UV-blocking and oxygen barrier properties provided by the protein. Therefore, electrospraying of food hydrocolloids interestingly appears as a novel potential nanotechnology tool toward the formulation of more stable functional foods and nutraceuticals.

  17. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants....

  18. Molecularly imprinted polymers with synthetic dummy templates for the preparation of capsaicin and dihydrocapsaicin from chili peppers.

    Science.gov (United States)

    Ma, Xiuli; Ji, Wenhua; Chen, Lingxiao; Wang, Xiao; Liu, Jianhua; Wang, Xueyong

    2015-01-01

    In this work, dummy molecularly imprinted polymers with high selectivity and affinity to capsaicin and dihydrocapsaicin are designed using N-vanillylnonanamide as a dummy template. The performance of dummy molecularly imprinted polymers and nonimprinted polymers was evaluated using adsorption isotherms, adsorption kinetics, and selective recognition capacity. Dummy molecularly imprinted polymers were found to exhibit good site accessibility, taking just 20 min to achieve adsorption equilibrium; they were also highly selective toward capsaicin and dihydrocapsaicin. We successfully used dummy molecularly imprinted polymers as a specific sorbent for selectively enriching capsaicin and dihydrocapsaicin from chili pepper samples. In a scaled-up experiment, the selective recovery of capsaicinoids was calculated to be 77.8% using solid-phase extraction. To the best of our knowledge, this is the first example of the use of N-vanillylnonanamide as a dummy template in molecularly imprinted polymers to simultaneously enrich capsaicin and dihydrocapsaicin. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Direct observation of the ultrafast electron transfer process in a polymer/fullerene blend. : Section Title: Physical Properties of Synthetic High Polymers

    NARCIS (Netherlands)

    Brabec, Ch J.; Zerza, G.; Sariciftci, N. S.; Cerullo, G.; Lanzani, G.; De Silvestri, S.; Hummelen, J. C.

    2001-01-01

    Optical studies on conjugated polymer-fullerene blends are performed with sub-10-fs temporal resoln. The photoinduced electron transfer process is directly monitored in the time domain, obtaining a forward electron transfer time const. of 45 fs. [on SciFinder(R)

  20. Solvent selection for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of synthetic polymers employing solubility parameters.

    Science.gov (United States)

    Brandt, Heike; Ehmann, Thomas; Otto, Matthias

    2010-08-30

    The principle relating to the selection of a proper matrix, cationization reagent, and solvent for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of synthetic polymers is still a topic of research. In this work we focused on the selection of a suitable MALDI solvent. Polystyrene PS7600 and poly(ethylene glycol) PEG4820 were analyzed by MALDI-TOF MS using various solvents which were selected based on the Hansen solubility parameter system. For polystyrene (PS), dithranol was used as the matrix and silver trifluoroacetate as the cationization reagent whereas, for poly(ethylene glycol) (PEG), the combination of 2,5-dihydroxybenzoic acid and sodium trifluoroacetate was used for all experiments. When employing solvents which dissolve PS and PEG, reliable MALDI mass spectra were obtained while samples in non-solvents (solvents which are not able to dissolve the polymer) failed to provide spectra. It seems that the solubility of the matrix and the cationization reagent are less important than the polymer solubility. 2010 John Wiley & Sons, Ltd.

  1. Influence of zinc chloride addition on the chemical structure of bio-oil obtained during co-pyrolysis of wood/synthetic polymer blends.

    Science.gov (United States)

    Rutkowski, Piotr

    2009-12-01

    The chemical structure of liquid products of the pinewood sawdust (W) co-pyrolysis with polystyrene (PS) and polypropylene (PP) with and without the zinc chloride as an additive was investigated. The pyrolysis process was carried out at 450 degrees C with the heating rate of 5 degrees C/min. The yield of liquid products of pyrolysis was in the range of 37-91 wt% and their form was liquid or semi-solid depending on the composition of the wood/polymer blend. The zinc chloride addition to wood/polymer blends has influenced the range of samples decomposition as well as the chemical structure of resulted bio-oils. All bio-oils from wood/polypropylene blends were two-phase (liquid and solid). Contrarily, all bio-oils obtained from biopolymer/polypropylene blends with zinc chloride added were yellow liquids. All analyses proved that the structure and the quality of bio-oil strongly depend on both the composition of the blend and the presence of ZnCl(2) as an additive. The FT-IR analyses of oils showed that oxygen-containing groups and hydrocarbons content highly depend on the composition of biomass/synthetic polymer mixture. The fractionation of bio-oils by column chromatography with four different solvents was followed by GC-MS analysis. Results confirmed the significant removal and/or transformation of oxygen-containing organic compounds due to the zinc chloride presence during pyrolysis process.

  2. Heart Attack

    Science.gov (United States)

    ... pain Fatigue Heart attack Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  3. Heart attack

    Science.gov (United States)

    ... heart attack. A stent is a small, metal mesh tube that opens up (expands) inside a coronary ... e228. PMID: 25260718 www.ncbi.nlm.nih.gov/pubmed/25260718 . Anderson JL. ST segment elevation acute myocardial ...

  4. Palladium-catalyzed alkyne polyannulation of diphenols and unactivated internal diynes: a new synthetic route to functional heterocyclic polymers

    OpenAIRE

    Zhang, Yun; Lam, Jacky W. Y.; Tang, Ben Zhong

    2016-01-01

    A new polymerization route for the preparation of functional heterocyclic polymers was developed from diphenol derivatives and unactivated internal diynes. The alkyne polyannulations of 4,4'-sulfonyldiphenol and 4,4'-(α,ω-alkylenedioxy)bis(diphenylacetylene)s or 1,2-bis[4-(2-phenylethynyl)phenyl]-1,2-diphenylethene were catalyzed by Pd2(dba)3 in the presence of bathophenanthroline, silver acetate and copper(II) acetate monohydrate in 1,4-dioxane at 130 °C, affording polymers with benzofuran m...

  5. Synthetic biocompatible polymers are an effective delivery platform that elicits potent antibody responses against HIV-1 glycopeptide immunogens

    Czech Academy of Sciences Publication Activity Database

    Francica, J.; Lynn, G.; Laga, Richard; Aussedat, B.; Meyerhoff, R.; Alam, M.; Danishefsky, S.; Haynes, B.; Seder, R.

    2016-01-01

    Roč. 32, Supplement 1 (2016), s. 221-P07.27 ISSN 0889-2229. [Conference on HIV Research for Prevention - HIV R4P. 17.10.2016-21.10.2016, Chicago] Institutional support: RVO:61389013 Keywords : biocompatible polymers * druh delivery Subject RIV: CD - Macromolecular Chemistry

  6. About Heart Attacks

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More About Heart Attacks Updated:Jan 27,2017 A heart attack is ... coronary artery damage leads to a heart attack . Heart Attack Questions and Answers What is a heart attack? ...

  7. Tuning the host-guest interactions in a phosphine coordination polymer through different types of post-synthetic modification.

    Science.gov (United States)

    Nuñez, Ana J; Chang, Maxwell S; Ibarra, Ilich A; Humphrey, Simon M

    2014-01-06

    The porous Phosphine Coordination Material, PCM-10 contains abundant free P(III) donor sites that can be subjected to a variety of post-synthetic modifications. The diverse P(III)/P(V) organic reactivity and coordination chemistry available to aryl phosphines have been exploited to decorate the pores of PCM-10, allowing for an extensive structure-function study. Polar P═O moieties, charged P(+)-CH3 phosphonium species with exchangeable coanions (I(-), F(-), BF4(-), and PF6(-)) and P-AuCl groups have been successfully post-synthetically incorporated. These modifications directly affect the strength of the resulting host-guest interactions, as demonstrated by comparative sorption studies of CO2, H2, and other gases in the solid-state. Broad tunability of the enthalpy of CO2 adsorption is observed: incorporation of BF4(-) ions inside the pores of PCM-10 results in 24% enhancement of the isosteric adsorption enthalpy of CO2 compared to the parent material, while F(-) anions induce a 36% reduction. Meanwhile, AuCl-decorated PCM-10 shows a high H2 sorption capacity of 4.72 wt % at 77 K and 1.0 bar, versus only 0.63 wt % in the unmodified material.

  8. Study on polymer fibers doped with phosphorescent Re(I) complex via electrospinning: synthetic strategy, structure, morphology and photophysical features.

    Science.gov (United States)

    Dejin, Wang; Qiang, Liu; Fei, Wang

    2014-01-01

    In the following paper, a Re(I) complex with electron-withdrawing oxadiazole group in its diamine ligand (denoted as N-N) was synthesized. Its single crystal structure analysis confirmed the successful synthesis of both ligand and complex. The central Re(I) ion localized in a traditional octahedral coordination environment. The diamine ligand 2-(pyridin-2-yl)-5-(p-tolyl)-1,3,4-oxadiazole (denoted as PPOZ) took a coplanar structure and the corresponding face-to-face π-π attraction between PPOZ ligands made the Re(I) complex molecules adjust a highly ordered arrangement which was positive to improve emissive performance. In order to repress the excited state geometric relaxation and further improve the emissive performance, the Re(I) complex was doped into a polymer host poly(vinylpyrrolidone) via electrospinning, resulting in composite fibers. The morphology of those composite fibers was analyzed by electron microscopy. The photophysical comparison between bulk sample and composite fibers indicated that the composite fibers showed emission blue shift, longer excited state lifetime and improved photostability. Further analysis suggested that the excited state geometric relaxation could be effectively repressed when the Re(I) complex molecules were immobilized in the polymer matrix, leading to above variations. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Use of xanthan and its binary blends with synthetic polymers to design controlled release formulations of buccoadhesive nystatin tablets.

    Science.gov (United States)

    Sakeer, Khalil; Al-Zein, Hind; Hassan, Issa; Martin, Gary P; Nokhodchi, Ali

    2010-01-01

    Various buccoadhesive nystatin tablets formulations containing xanthan, carbopols (934P, 971P, 974P), PVP K30 or PEG 6000 or their binary blends were prepared. The powders were compressed into tablets at a constant compression pressure. Drug release behaviour, swelling and erosion indices and strength of bioadhesion in vitro to a biological membrane were investigated. The interaction between nystatin and polymers was investigated by DSC and FT-IR. Tablets containing the different types of carbopol alone consistently showed an initial burst release of drug, whereas this was not observed for matrices containing xanthan or xanthan-carbopol. The presence of PEG in xanthan-containing formulations induced an increase in dissolution rate; however, in the absence of xanthan the amount of drug release from a PEG matrix was reduced to xanthan matrix as a result of interaction between the polymer and calcium ions. Xanthan can be used in potential mucoadhesive formulations containing nystatin to produce a controlled release of the drug and the outcomes of this work may provide a suitable strategy for matrix selection to provide more efficacious treatment alternatives for candidiasis and other disease processes for significant patient populations.

  10. Comparison of the in Vitro Uptake and Toxicity of Collagen- and Synthetic Polymer-Coated Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Oana T. Marisca

    2015-08-01

    Full Text Available We studied the physico-chemical properties (size, shape, zeta-potential, cellular internalization and toxicity of gold nanoparticles (NPs stabilized with the most abundant mammalian protein, collagen. The properties of these gold NPs were compared to the same sized gold NPs coated with synthetic poly(isobutylene-alt-maleic anhydride (PMA. Intracellular uptake and cytotoxicity were assessed in two cell lines (cervical carcinoma and lung adenocarcinoma cells by employing inductively-coupled plasma-mass spectrometry (ICP-MS analysis and a cell viability assay based on 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT, respectively. We found that the collagen-coated gold NPs exhibit lower cytotoxicity, but higher uptake levels than PMA-coated gold NPs. These results demonstrate that the surface coating of Au NPs plays a decisive role in their biocompatibility.

  11. Combined Effect of Synthetic and Natural Polymers in Preparation of Cetirizine Hydrochloride Oral Disintegrating Tablets: Optimization by Central Composite Design

    Directory of Open Access Journals (Sweden)

    Chandra Sekhar Patro

    2017-01-01

    Full Text Available Our aim was to employ experimental design to formulate and optimize cetirizine hydrochloride oral disintegrating tablets (ODTs by direct compression technique, using the mutual effect of synthetic croscarmellose sodium (CCS and natural Hibiscus rosa-sinensis mucilage (HRM as disintegrants in the formulation. Central composite design (CCD was applied to optimize the influence of three levels each of CCS (X1 and HRM (X2 concentrations (independent variables for investigated responses: disintegration time (DT (Y1, % friability (F (Y2, and % cumulative drug release (DR (Y3 (dependent variables. This face-centered second-order model’s reliability was verified by the probability and adequate precision values from the analysis of variance, while the significant factor effects influencing the studied responses were identified using multiple linear regression analysis. Perturbation and response surface plots were interpreted to evaluate the responses’ sensitivity towards the variables. During optimization, the concentrations of the processed factors were evaluated, and the resulting values were in good agreement with predicted estimates endorsing the validity. Spectral study by Fourier Transform Infrared Spectroscopy (FTIR and thermograms from Differential Scanning Calorimetry (DSC demonstrated the drug-excipients compatibility of the optimized formulation. The optimized formulation has concentrations of 9.05 mg and 16.04 mg of CCS and HRM each, respectively, and the model predicted DT of 13.271 sec, F of 0.498, and DR of 99.768%.

  12. Combined Effect of Synthetic and Natural Polymers in Preparation of Cetirizine Hydrochloride Oral Disintegrating Tablets: Optimization by Central Composite Design.

    Science.gov (United States)

    Patro, Chandra Sekhar; Sahu, Prafulla Kumar

    2017-01-01

    Our aim was to employ experimental design to formulate and optimize cetirizine hydrochloride oral disintegrating tablets (ODTs) by direct compression technique, using the mutual effect of synthetic croscarmellose sodium (CCS) and natural Hibiscus rosa-sinensis mucilage (HRM) as disintegrants in the formulation. Central composite design (CCD) was applied to optimize the influence of three levels each of CCS ( X 1 ) and HRM ( X 2 ) concentrations (independent variables) for investigated responses: disintegration time (DT) ( Y 1 ), % friability ( F ) ( Y 2 ), and % cumulative drug release (DR) ( Y 3 ) (dependent variables). This face-centered second-order model's reliability was verified by the probability and adequate precision values from the analysis of variance, while the significant factor effects influencing the studied responses were identified using multiple linear regression analysis. Perturbation and response surface plots were interpreted to evaluate the responses' sensitivity towards the variables. During optimization, the concentrations of the processed factors were evaluated, and the resulting values were in good agreement with predicted estimates endorsing the validity. Spectral study by Fourier Transform Infrared Spectroscopy (FTIR) and thermograms from Differential Scanning Calorimetry (DSC) demonstrated the drug-excipients compatibility of the optimized formulation. The optimized formulation has concentrations of 9.05 mg and 16.04 mg of CCS and HRM each, respectively, and the model predicted DT of 13.271 sec, F of 0.498, and DR of 99.768%.

  13. Experimental Study of Rheological Properties and Oil Displacement Efficiency in Oilfields for a Synthetic Hydrophobically Modified Polymer.

    Science.gov (United States)

    Liu, Pengcheng; Mu, Zhenbao; Wang, Chao; Wang, Yanling

    2017-08-18

    In a previous study, we developed a synthetic hydrophobically modified hydroxyethyl cellulose (HEC) using bromododecane (BD), which we denote as BD-HMHEC. In this work, we continually investigate the rheological properties and its oil displacement efficiency in PuTao well area in Daqing oilfields, China. Results show that BD-HMHEC solution has good viscosification, thermal-resistance, salt-tolerance, shear resistance, and acid/alkali resistance. The storage modulus (G') and the loose modulus (G") of the BD-HMHEC solutions increase significantly with increasing BD-HMHEC concentration, and the solution becomes viscoelastic at a sufficiently high BD-HMHEC concentration. The core flooding results showed BD-HMHEC flooding improves oil recovery by 7-14% in comparison with HEC flooding at concentrations of 4,000 mg/L under equivalent conditions. Moreover, BD-HMHEC flooding improves oil recovery by 7-8% after conducting water and hydrolyzed polyacrylamide (HPAM) flooding. The oil displacement mechanism of BD-HMHEC solutions is discussed based on a visual evaluation. The results indicate that BD-HMHEC flooding is a feasible means for improving oil recovery after water/HPAM flooding.

  14. Synthetic Architecture of MgO/C Nanocomposite from Hierarchical-Structured Coordination Polymer toward Enhanced CO2 Capture.

    Science.gov (United States)

    Li, Ping; Liu, Wen; Dennis, John S; Zeng, Hua Chun

    2017-03-22

    Highly efficient, durable, and earth-abundant solid sorbents are of paramount importance for practical carbon capture, storage, and utilization. Here, we report a novel and facile two-step strategy to synthesize a group of hierarchically structured porous MgO/C nanocomposites using flowerlike Mg-containing coordination polymer as a precursor. The new nanocomposites exhibit superb CO2 capture performance with sorption capacity up to 30.9 wt % (at 27 °C, 1 bar CO2), fast sorption kinetics, and long cycling life. Importantly, the achieved capacity is >14 times higher than that of commercial MgO, and favorably exceeds the highest value recorded to date for MgO-based sorbents under similar operating conditions. On the basis of the morphological and textural property analysis, together with CO2 sorption mechanism study using CO2-TPD and DRIFT techniques, the outstanding performance in CO2 uptake originates from unique features of this type of sorbent materials, which include hierarchical architecture, porous building blocks of nanosheets, high specific surface area (ca. 300 m2/g), evenly dispersed MgO nanocrystallites (ca. 3 nm) providing abundant active sites, and the in situ generated carbon matrix that acts as a stabilizer to prevent the growth and agglomeration of MgO crystallites. The nanocomposite system developed in this work shows good potential for future low-cost CO2 abatement and utilization.

  15. Osteogenic induction of human bone marrow-derived mesenchymal progenitor cells in novel synthetic polymer-hydrogel matrices.

    Science.gov (United States)

    Endres, M; Hutmacher, D W; Salgado, A J; Kaps, C; Ringe, J; Reis, R L; Sittinger, M; Brandwood, A; Schantz, J T

    2003-08-01

    The aim of this project was to investigate the in vitro osteogenic potential of human mesenchymal progenitor cells in novel matrix architectures built by means of a three-dimensional bioresorbable synthetic framework in combination with a hydrogel. Human mesenchymal progenitor cells (hMPCs) were isolated from a human bone marrow aspirate by gradient centrifugation. Before in vitro engineering of scaffold-hMPC constructs, the adipogenic and osteogenic differentiation potential was demonstrated by staining of neutral lipids and induction of bone-specific proteins, respectively. After expansion in monolayer cultures, the cells were enzymatically detached and then seeded in combination with a hydrogel into polycaprolactone (PCL) and polycaprolactone-hydroxyapatite (PCL-HA) frameworks. This scaffold design concept is characterized by novel matrix architecture, good mechanical properties, and slow degradation kinetics of the framework and a biomimetic milieu for cell delivery and proliferation. To induce osteogenic differentiation, the specimens were cultured in an osteogenic cell culture medium and were maintained in vitro for 6 weeks. Cellular distribution and viability within three-dimensional hMPC bone grafts were documented by scanning electron microscopy, cell metabolism assays, and confocal laser microscopy. Secretion of the osteogenic marker molecules type I procollagen and osteocalcin was analyzed by semiquantitative immunocytochemistry assays. Alkaline phosphatase activity was visualized by p-nitrophenyl phosphate substrate reaction. During osteogenic stimulation, hMPCs proliferated toward and onto the PCL and PCL-HA scaffold surfaces and metabolic activity increased, reaching a plateau by day 15. The temporal pattern of bone-related marker molecules produced by in vitro tissue-engineered scaffold-cell constructs revealed that hMPCs differentiated better within the biomimetic matrix architecture along the osteogenic lineage.

  16. Analytical development of the sup 252 Cf-plasma desorption mass spectroscopy for the structure analysis of biopolymers and synthetic polymers. Analytische Entwicklung der sup 252 Cf-Plasmadesorptions-Massenspektrometrie zur Strukturanalyse von Biopolymeren und synthetischen Polymeren

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, K.

    1991-01-01

    The dissertation had the following aims: A systematic, analytical development of the plasma desorption method, and applications of the plasma desorption mass spectroscopy (PDMS) in primary structure investigations of polypeptides and proteins, and for the determination of the molecular weight of synthetic polymers. For the analytical development of the PDMS, aspects of main interest were the preparation and characterization techniques, and systematic model investigations of the analytical sensitivity, reproducibility and accuray of the molecular weight determination, as well as of the mixture analysis. The objective in the second part of the dissertation was to show application potentials and limits of the PDMS within the framework of analytical tasks of a primary structure characterization of polypeptides and proteins, as well as with regard to the determination of molecular weight and molecular weight distribution of synthetic polymers. (orig.).

  17. Multi-​Dimensional Separations of Polymers

    NARCIS (Netherlands)

    Schoenmakers, P.; Aarnoutse, P.

    2014-01-01

    Synthetic polymers and comprehensive two-​dimensional liq. chromatog. (LC×LC) are a synergistic combination. LC×LC provides unique insights in mutually dependent mol. distributions. Synthetic polymers offer clear demonstrations of the value of LC×LC.

  18. Synthesis and characterization of a novel molecularly imprinted polymer for simultaneous extraction and determination of water-soluble and fat-soluble synthetic colorants in chilli products by solid phase extraction and high performance liquid chromatography.

    Science.gov (United States)

    Long, Chaoyang; Mai, Zhibin; Yang, Yingfen; Zhu, Binghui; Xu, Xiumin; Lu, Lin; Zou, Xiaoyong

    2009-11-20

    A sorbent was synthesized and investigated for molecularly imprinted solid phase extraction (MISPE). Molecularly imprinted polymers (MIP) were synthesized via precipitation polymerization procedure, where 4-vinyl pyridine (4-VP) was used as functional monomer and ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The imprinting effect of the MISPE was evaluated by elution experiments. The resulting MISPE showed high extraction selectivity to water-soluble and fat-soluble synthetic colorants. The determination of multi-residue for three kinds of water-soluble and six kinds of fat-soluble synthetic colorants in chilli products was also investigated by HPLC coupled with MISPE. The mean recoveries calculated by solvent calibration curve for water-soluble and fat-soluble synthetic colorants were from 72.1% to 95.6% for chilli spice and 72.1% to 92.3% for chilli powder. The decision limit (CCalpha) and the detection capability (CCbeta) obtained for water-soluble and fat-soluble synthetic colorants were in the range of 1.2-1.6 and 1.9-2.4 microg kg(-1) in chilli spice and chilli powder. The resulting MISPE was successfully used off-line for the determination of nine kinds of synthetic colorants in chilli products.

  19. Synthetic Versus Tissue-Engineered Implants for Joint Replacement

    Directory of Open Access Journals (Sweden)

    Duncan E. T. Shepherd

    2007-01-01

    Full Text Available Human synovial joints are remarkable as they can last for a lifetime. However, they can be affected by disease that may lead to destruction of the joint surface. The most common treatment in the advanced stages of joint disease is artificial joint replacement, where the diseased synovial joint is replaced with an artificial implant made from synthetic materials, such as metals and polymers. A new technique for repairing diseased synovial joints is tissue engineering where cells are used to grow replacement tissue. This paper explores the relative merits of synthetic and tissue-engineered implants, using joint replacement as an example. Synthetic joint replacement is a well-established procedure with the advantages of early mobilisation, pain relief and high patient satisfaction. However, synthetic implants are not natural tissues; they can cause adverse reactions to the body and there could be a mismatch in mechanical properties compared to natural tissues. Tissue-engineered implants offer great potential and have major advantages over synthetic implants as they are natural tissue, which should ensure that they are totally biocompatible, have the correct mechanical properties and integrate well with the existing tissue. However, there are still many limitations to be addressed in tissue engineering such as scaling up for production, bioreactor design, appropriate regulation and the potential for disease to attack the new tissue-engineered implant.

  20. Star Polymers.

    Science.gov (United States)

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  1. Fluorescence spectroscopy in polymer science

    NARCIS (Netherlands)

    Raja, T.N.; Brouwer, A.M.; Demchenko, A.P.

    2011-01-01

    Polymer science is an interdisciplinary field, combining chemistry, physics, and in some cases biology. Structure, morphology, and dynamical phenomena in natural and synthetic polymers can be addressed using fluorescence spectroscopy. The most attractive aspect of fluorescent reporters is that their

  2. Edible Polymers: Challenges and Opportunities

    Directory of Open Access Journals (Sweden)

    Subhas C. Shit

    2014-01-01

    Full Text Available Edible polymers have established substantial deliberation in modern eons because of their benefits comprising use as edible materials over synthetic polymers. This could contribute to the reduction of environmental contamination. Edible polymers can practically diminish the complexity and thus improve the recyclability of materials, compared to the more traditional non-environmentally friendly materials and may be able to substitute such synthetic polymers. A synthetic hydrogel polymer unlocked a new possibility for development of films, coatings, extrudable pellets, and synthetic nanopolymers, particularly designed for medical, agricultural, and industrial fields. Edible polymers offer many advantages for delivering drugs and tissue engineering. Edible polymer technology helps food industries to make their products more attractive and safe to use. Novel edible materials have been derived from many natural sources that have conventionally been regarded as discarded materials. The objective of this review is to provide a comprehensive introduction to edible polymers by providing descriptions in terms of their origin, properties, and potential uses.

  3. Solidarity under Attack

    DEFF Research Database (Denmark)

    Meret, Susi; Goffredo, Sergio

    2017-01-01

    https://www.opendemocracy.net/can-europe-make-it/susi-meret-sergio-goffredo/solidarity-under-attack......https://www.opendemocracy.net/can-europe-make-it/susi-meret-sergio-goffredo/solidarity-under-attack...

  4. Social engineering attack framework

    CSIR Research Space (South Africa)

    Mouton, F

    2014-07-01

    Full Text Available link. A social engineering attack targets this weakness by; using various manipulation techniques in order to elicit sensitive; information. The field of social engineering is still in its infancy; stages with regards to formal definitions and attack...

  5. Pericarditis - after heart attack

    Science.gov (United States)

    ... include: A previous heart attack Open heart surgery Chest trauma A heart attack that has affected the thickness of your heart muscle Symptoms Symptoms include: Anxiety Chest pain from the swollen pericardium rubbing on the ...

  6. Heart attack first aid

    Science.gov (United States)

    First aid - heart attack; First aid - cardiopulmonary arrest; First aid - cardiac arrest ... A heart attack occurs when the blood flow that carries oxygen to the heart is blocked. The heart muscle ...

  7. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an artery for a short time. The only difference between a stroke ...

  8. Composite Dos Attack Model

    Directory of Open Access Journals (Sweden)

    Simona Ramanauskaitė

    2012-04-01

    Full Text Available Preparation for potential threats is one of the most important phases ensuring system security. It allows evaluating possible losses, changes in the attack process, the effectiveness of used countermeasures, optimal system settings, etc. In cyber-attack cases, executing real experiments can be difficult for many reasons. However, mathematical or programming models can be used instead of conducting experiments in a real environment. This work proposes a composite denial of service attack model that combines bandwidth exhaustion, filtering and memory depletion models for a more real representation of similar cyber-attacks. On the basis of the introduced model, different experiments were done. They showed the main dependencies of the influence of attacker and victim’s properties on the success probability of denial of service attack. In the future, this model can be used for the denial of service attack or countermeasure optimization.

  9. Rapid identification of synthetic colorants in food samples by using indium oxide nanoparticle-functionalized porous polymer monolith coupled with HPLC-MS/MS.

    Science.gov (United States)

    Qi, Ruifang; Zhou, Xiao; Li, Xiqian; Ma, Jiutong; Lu, Chunmei; Mu, Jun; Zhang, Xuguang; Jia, Qiong

    2014-12-07

    A synthetic protocol for the preparation of an indium oxide nanoparticle-functionalized poly(methacrylic acid-glycidyl methacrylate-ethylene dimethacrylate-ethanediamine) monolithic column is reported. Various techniques, including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermal gravimetric analysis-derivative thermogravimetric analysis were employed to characterize the synthesized monolith. The modified monolithic column was coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for determining synthetic colorants in various food samples. Under optimized conditions, good linearity was obtained for all the targets with squared regression coefficients greater than 0.9982. The limits of detection (S/N = 3) for 12 synthetic colorants were in the range of 0.012-2.97 μg kg(-1). The intra-day and inter-day relative standard deviations, ranging from 2.7% to 8.5%, were within the acceptable range. The developed method was successfully applied to the determination of synthetic colorants in food samples (candy, milk, jelly, jam, canned food, juice, and carbonated drink). Target recoveries at different spiked levels ranged from 73.5% to 112.1% with relative standard deviations of less than 10.3%.

  10. Nocturnal panic attacks

    OpenAIRE

    Lopes Fabiana L.; Nardi Antonio E.; Nascimento Isabella; Valença Alexandre M.; Zin Walter A

    2002-01-01

    The panic-respiration connection has been presented with increasing evidences in the literature. We report three panic disorder patients with nocturnal panic attacks with prominent respiratory symptoms, the overlapping of the symptoms with the sleep apnea syndrome and a change of the diurnal panic attacks, from spontaneous to situational pattern. The implication of these findings and awareness to the distinct core of the nocturnal panic attacks symptoms may help to differentiate them from sle...

  11. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... stroke symptoms. Popular Topics TIA Cardiac Catheter Cholesterol Heart Attack Stent © 2018, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. ...

  12. Seven Deadliest Network Attacks

    CERN Document Server

    Prowell, Stacy; Borkin, Mike

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting networks? Then you need Seven Deadliest Network Attacks. This book pinpoints the most dangerous hacks and exploits specific to networks, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Denial of Service War Dialing Penetration "Testing" Protocol Tunneling Spanning Tree At

  13. Seven deadliest USB attacks

    CERN Document Server

    Anderson, Brian

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting USB technology? Then you need Seven Deadliest USB Attacks. This book pinpoints the most dangerous hacks and exploits specific to USB, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: USB Hacksaw USB Switchblade USB Based Virus/Malicous Code Launch USB Device Overflow RAMdum

  14. Seven Deadliest Microsoft Attacks

    CERN Document Server

    Kraus, Rob; Borkin, Mike; Alpern, Naomi

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting Microsoft products? Then you need Seven Deadliest Microsoft Attacks. This book pinpoints the most dangerous hacks and exploits specific to Microsoft applications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Windows Operating System-Password AttacksActive Directory-Escalat

  15. Heart attack - discharge

    Science.gov (United States)

    ... attack Heart bypass surgery Heart bypass surgery - minimally invasive Heart pacemaker High blood cholesterol levels High blood pressure Implantable cardioverter-defibrillator Smoking - tips on how to ...

  16. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... stroke symptoms. Popular Topics TIA Cardiac Catheter Cholesterol Heart Attack Stent © 2017, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. ...

  17. Versatile synthetic strategy for coating upconverting nanoparticles with polymer shells through localized photopolymerization by using the particles as internal light sources.

    Science.gov (United States)

    Beyazit, Selim; Ambrosini, Serena; Marchyk, Nataliya; Palo, Emilia; Kale, Vishal; Soukka, Tero; Tse Sum Bui, Bernadette; Haupt, Karsten

    2014-08-18

    We present a straightforward and generic strategy for coating upconverting nanoparticles (UCPs) with polymer shells for their protection, functionalization, conjugation, and for biocompatibility. UCPs are attracting much attention for their potential use as fluorescent labels in biological applications. However, they are hydrophobic and non-compatible with aqueous media; thus prior surface modification is essential. Our method uses the internal UV or visible light emitted from UCPs upon photoexcitation with near-infrared radiation, to locally photopolymerize a thin polymer shell around the UCPs. In this way, a large variety of monomers with different chemical functionalities can be incorporated. If required, a second layer can be added on top of the first. Our method can provide a large spectrum of surface functional groups rapidly and in one pot, hence offering a platform for the preparation of libraries of functional polymer-encapsulated UCPs for applications in bioassays, biosensing, optical imaging, and theranostics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Polymers – A New Open Access Scientific Journal on Polymer Science

    Directory of Open Access Journals (Sweden)

    Shu-Kun Lin

    2009-12-01

    Full Text Available Polymers is a new interdisciplinary, Open Access scientific journal on polymer science, published by Molecular Diversity Preservation International (MDPI. This journal welcomes manuscript submissions on polymer chemistry, macromolecular chemistry, polymer physics, polymer characterization and all related topics. Both synthetic polymers and natural polymers, including biopolymers, are considered. Manuscripts will be thoroughly peer-reviewed in a timely fashion, and papers will be published, if accepted, within 6 to 8 weeks after submission. [...

  19. Polymers in cell encapsulation from an enveloped cell perspective

    NARCIS (Netherlands)

    de Vos, Paul; Lazarjani, Hamideh Aghajani; Poncelet, Denis; Faas, Marijke M.

    2014-01-01

    In the past two decades, many polymers have been proposed for producing immunoprotective capsules. Examples include the natural polymers alginate, agarose, chitosan, cellulose, collagen, and xanthan and synthetic polymers poly(ethylene glycol), polyvinyl alcohol, polyurethane, poly(ether-sulfone),

  20. Plants under dual attack

    NARCIS (Netherlands)

    Ponzio, C.A.M.

    2016-01-01

    Though immobile, plants are members of complex environments, and are under constant threat from a wide range of attackers, which includes organisms such as insect herbivores or plant pathogens. Plants have developed sophisticated defenses against these attackers, and include chemical responses such

  1. Transient Ischemic Attack

    Medline Plus

    Full Text Available Transient Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an artery for a short time. The only ... TIA is that with TIA the blockage is transient (temporary). TIA symptoms occur rapidly and last a ...

  2. A facile strategy for fabrication of aggregation-induced emission (AIE) active fluorescent polymeric nanoparticles (FPNs) via post modification of synthetic polymers and their cell imaging.

    Science.gov (United States)

    Liu, Yanzhu; Mao, Liucheng; Liu, Xinhua; Liu, Meiying; Xu, Dazhuang; Jiang, Ruming; Deng, Fengjie; Li, Yongxiu; Zhang, Xiaoyong; Wei, Yen

    2017-10-01

    Aggregation-induced emission (AIE) active fluorescent polymeric nanoparticles (FPNs) have recently emerged as the promising nanoprobes for biological imaging for their intensive fluorescence, good photostability, desirable biocompatibility and well designability of structure and optical properties. Herein, we proposed a novel strategy for fabrication of AIE-active FPNs through the post modification of synthetic copolymers to form Schiff base. The size, morphology, optical properties and biocompatibility as well as cell uptake behavior were evaluated in detailed. To fabricate these AIE-active FPNs, poly(PEG-co-VA) copolymers were first obtained via addition-fragmentation chain transfer polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3-vinylaniline (VA) as the monomers. Then the AIE-active SA-poly(PEG-co-VA) FPNs were formed through the reaction between salicylaldehyde (SA) and VA. Results demonstrated that SA-poly(PEG-co-VA) FPNs possess bright fluorescence, superior photo-bleaching resistance, excellent biocompatibility and efficient cell uptake behavior. To the best of our knowledge, this is the first report for fabrication AIE-active FPNs through post modification of synthetic copolymers. The facile fabrication procedure and the remarkable features suggested that these AIE-active FPNs promising candidates for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Mathematical Attacks on RSA Cryptosystem

    OpenAIRE

    Imad K. Salah; Abdullah Darwish; Saleh Oqeili

    2006-01-01

    In this paper some of the most common attacks against Rivest, Shamir, and Adleman (RSA) cryptosystem are presented. We describe the integer factoring attacks, attacks on the underlying mathematical function, as well as attacks that exploit details in implementations of the algorithm. Algorithms for each type of attacks are developed and analyzed by their complexity, memory requirements and area of usage.

  4. Nocturnal panic attacks

    Directory of Open Access Journals (Sweden)

    Lopes Fabiana L.

    2002-01-01

    Full Text Available The panic-respiration connection has been presented with increasing evidences in the literature. We report three panic disorder patients with nocturnal panic attacks with prominent respiratory symptoms, the overlapping of the symptoms with the sleep apnea syndrome and a change of the diurnal panic attacks, from spontaneous to situational pattern. The implication of these findings and awareness to the distinct core of the nocturnal panic attacks symptoms may help to differentiate them from sleep disorders and the search for specific treatment.

  5. Application of Liquid-Phase Direct Fluorination: Novel Synthetic Methods for a Polyfluorinated Coating Material and a Monomer of a Perfluorinated Polymer Electrolyte Membrane

    Directory of Open Access Journals (Sweden)

    Takashi Okazoe

    2012-04-01

    Full Text Available A new polyfluorinated anti-staining coating material CF3O(CF2CF2OxCF2-CONHCH2CH2CH2Si(OCH33 has been developed by utilizing the PERFECT method, which employs a liquid-phase direct fluorination reaction with elemental fluorine as a key step. Direct fluorination of a partially-fluorinated ester, which was prepared from a non-fluorinated poly(ethylene glycol and a perfluorinated acyl fluoride, followed by methanolysis, gave the perfluorinated corresponding compound, which was led to the coating material for surface treating agents, and the methyl ester of the starting perfluorinated acyl fluoride. Application to the synthesis of a new perfluorinated bifunctional sulfonate monomer CF2=CFOCF2CF2CF2OCF(CF2SO2F2 for polymer electrolyte membranes (PEMs of fuel cells was also developed.

  6. Heart Attack Payment - State

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – state data. This data set includes state-level data for payments associated with a 30-day episode of care for heart...

  7. Heart Attack Payment - Hospital

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – provider data. This data set includes provider data for payments associated with a 30-day episode of care for heart...

  8. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an ... a short time. The only difference between a stroke and TIA is that with TIA the blockage ...

  9. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... immediately for any stroke symptoms. Popular Topics TIA Cardiac Catheter Cholesterol Heart Attack Stent © 2018, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. ...

  10. Heart Attack Payment - National

    Data.gov (United States)

    U.S. Department of Health & Human Services — Payment for heart attack patients measure – national data. This data set includes national-level data for payments associated with a 30-day episode of care for heart...

  11. Cooperating attackers in neural cryptography.

    Science.gov (United States)

    Shacham, Lanir N; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the "majority-flipping attacker," does not decay with the parameters of the model. This attacker's outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  12. Facial Dog Attack Injuries

    OpenAIRE

    Lin, Wei; Patil, Pavan Manohar

    2013-01-01

    The exposed position of the face makes it vulnerable to dog bite injuries. This fact combined with the short stature of children makes them a high-risk group for such attacks. In contrast to wounds inflicted by assaults and accidents, dog bite wounds are deep puncture type wounds compounded by the presence of pathologic bacteria from the saliva of the attacking dog. This, combined with the presence of crushed, devitalized tissue makes these wounds highly susceptible to infection. Key to succe...

  13. Launch under attack

    Energy Technology Data Exchange (ETDEWEB)

    Steinbruner, J.

    1984-01-01

    The strategy of launch under attack calls for launching nuclear weapons on warning that attacking weapons are on their way. The political pressures for adopting this strategy are symptomatic of an increasing instability in the nuclear balance. The author describes a Brookings Institute model, which indicates that the problems of decentralized control and precise timing could lead to failures in retargeting procedures. The major concern is that the strategy imposes powerful incentives for preemption as the most promising means of conducting nuclear war.

  14. The attack navigator

    DEFF Research Database (Denmark)

    Probst, Christian W.; Willemson, Jan; Pieters, Wolter

    2016-01-01

    The need to assess security and take protection decisions is at least as old as our civilisation. However, the complexity and development speed of our interconnected technical systems have surpassed our capacity to imagine and evaluate risk scenarios. This holds in particular for risks that are c......The need to assess security and take protection decisions is at least as old as our civilisation. However, the complexity and development speed of our interconnected technical systems have surpassed our capacity to imagine and evaluate risk scenarios. This holds in particular for risks...... that are caused by the strategic behaviour of adversaries. Therefore, technology-supported methods are needed to help us identify and manage these risks. In this paper, we describe the attack navigator: a graph-based approach to security risk assessment inspired by navigation systems. Based on maps of a socio......-technical system, the attack navigator identifies routes to an attacker goal. Specific attacker properties such as skill or resources can be included through attacker profiles. This enables defenders to explore attack scenarios and the effectiveness of defense alternatives under different threat conditions....

  15. [The evaluation of ketoprofen pharmaceutical availability in the presence of a dry extract from goldenrod (Solidago virgaurea L.) of synthetic polymer vehicles].

    Science.gov (United States)

    Berner-Strzelczyk, Aneta; Kołodziejska, Justyna; Piechota-Urbańska, Magdalena; Zgoda, Marian Mikołaj

    2009-01-01

    The aim of this study was to produce hydrogels for topical use and having strengthened anti-inflammatory, analgesic and antirheumatic activity. To obtain the above effect dry standardized plant extract was added to enrich a formulation containing therapeutic agent (ketoprofen) from the group of nonsteroidal anti-inflammatory drugs. Dry standardized extract from Solidago virgaurea L. of confirmed anti-inflammatory activity was selected for this purpose. The derivatives of acrylic acid polymers (Carbopol Ultrez and Carbopol 980) were used as the formulation vehicles. These vehicles were selected owing to their high applicative properties--transparency, resistance to changes of temperature, perfect tactile and esthetic qualities, no sensitizing agents, no toxicity and lack of influence on therapeutic properties of the therapeutic agent and compatibility in the pharmaceutical phase. The produced formulations were exposed to basic physicochemical tests--pH, viscosity parameters (structural viscosity, yield stress and thixotropy), pharmaceutical availability and durability after six months of storage. The effect of component plant extracts on the process of ketoprofen diffusion to acceptor fluid through a semipermeable membrane was also compared. The obtained results indicate that dry standardized extract from Solidago virgaurea L. does not affect significantly the process of ketoprofen release from the tested preparations. After six months of storage the preparations with ketoprofen demonstrate rheological stability and high pharmaceutical availability.

  16. Molecularly imprinted polymers with synthetic dummy template for simultaneously selective removal and enrichment of ginkgolic acids from Ginkgo biloba L. leaves extracts.

    Science.gov (United States)

    Ji, Wenhua; Ma, Xiuli; Xie, Hongkai; Chen, Lingxiao; Wang, Xiao; Zhao, Hengqiang; Huang, Luqi

    2014-11-14

    Dummy molecularly imprinted polymers (DMIPs) for simultaneously selective removal and enrichment of ginkgolic acids (GAs) during the processing of Ginkgo biloba leaves have been prepared. Two dummy template molecule with similar structural skeleton to GAs, 6-methoxysalicylic acid (MOSA, DT-1) and 6-hexadecyloxysalicylic acid (HOSA, DT-2), have been designed and synthesized. The performance of the DMIPs and NIPs were evaluated including selective recognition capacity, adsorption isotherm, and adsorption kinetics. The selective recognition capacity of the three GAs with four analogues on the sorbents illustrated that the DMIPs sorbents have high specificity for GAs. An efficient method based on DMIP-HOSA coupled with solid-phase extraction (SPE) was developed for simultaneously selective removal and enrichment of ginkgolic acids (GAs) during the processing of Ginkgo biloba leaves. The method showed excellent recoveries (82.5-88.7%) and precision (RSD 0.5-2.6%, n=5) for licorice extracts, Gastrodia elata extracts and pepper extracts spiked at three concentration levels each (50, 100, 200 μg mL(-1)). The results indicated that GAs and standardized Ginkgo biloba leaves extracts could be obtained simultaneously through the DMIP-SPE. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Cyber Attacks, Information Attacks, and Postmodern Warfare

    Directory of Open Access Journals (Sweden)

    Valuch Jozef

    2017-06-01

    Full Text Available The aim of this paper is to evaluate and differentiate between the phenomena of cyberwarfare and information warfare, as manifestations of what we perceive as postmodern warfare. We describe and analyse the current examples of the use the postmodern warfare and the reactions of states and international bodies to these phenomena. The subject matter of this paper is the relationship between new types of postmodern conflicts and the law of armed conflicts (law of war. Based on ICJ case law, it is clear that under current legal rules of international law of war, cyber attacks as well as information attacks (often performed in the cyberspace as well can only be perceived as “war” if executed in addition to classical kinetic warfare, which is often not the case. In most cases perceived “only” as a non-linear warfare (postmodern conflict, this practice nevertheless must be condemned as conduct contrary to the principles of international law and (possibly a crime under national laws, unless this type of conduct will be recognized by the international community as a “war” proper, in its new, postmodern sense.

  18. Synthetic Biology: Applications Come of Age

    OpenAIRE

    Khalil, Ahmad S.; Collins, James J.

    2010-01-01

    Synthetic biology is bringing together engineers and biologists to design and build novel biomolecular components, networks and pathways, and to use these constructs to rewire and reprogram organisms. These re-engineered organisms will change our lives in the coming years, leading to cheaper drugs, “green” means to fuel our cars, and targeted therapies to attack “superbugs” and diseases such as cancer. The de novo engineering of genetic circuits, biological modules, and synthetic pathways is ...

  19. Cooperating attackers in neural cryptography

    Science.gov (United States)

    Shacham, Lanir N.; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the “majority-flipping attacker,” does not decay with the parameters of the model. This attacker’s outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  20. Seven Deadliest Wireless Technologies Attacks

    CERN Document Server

    Haines, Brad

    2010-01-01

    How can an information security professional keep up with all of the hacks, attacks, and exploits? One way to find out what the worst of the worst are is to read the seven books in our Seven Deadliest Attacks Series. Not only do we let you in on the anatomy of these attacks but we also tell you how to get rid of them and how to defend against them in the future. Countermeasures are detailed so that you can fight against similar attacks as they evolve. Attacks featured in this book include:Bluetooth AttacksCredit Card, Access Card, and Passport AttacksBad Encryption

  1. The political attack ad

    Directory of Open Access Journals (Sweden)

    Palma Peña-Jiménez, Ph.D.

    2011-01-01

    Full Text Available During election campaigns the political spot has a clear objective: to win votes. This message is communicated to the electorate through television and Internet, and usually presents a negative approach, which includes a direct critical message against the opponent, rather than an exposition of proposals. This article is focused on the analysis of the campaign attack video ad purposely created to encourage the disapproval of the political opponent among voters. These ads focus on discrediting the opponent, many times, through the transmission of ad hominem messages, instead of disseminating the potential of the political party and the virtues and manifesto of its candidate. The article reviews the development of the attack ad since its first appearance, which in Spain dates back to 1996, when the famous Doberman ad was broadcast, and examines the most memorable campaign attack ads.

  2. Dendritic Polymers for Theranostics

    OpenAIRE

    Ma, Yuan; Mou, Quanbing; Wang, Dali; Zhu, Xinyuan; Yan, Deyue

    2016-01-01

    Dendritic polymers are highly branched polymers with controllable structures, which possess a large population of terminal functional groups, low solution or melt viscosity, and good solubility. Their size, degree of branching and functionality can be adjusted and controlled through the synthetic procedures. These tunable structures correspond to application-related properties, such as biodegradability, biocompatibility, stimuli-responsiveness and self-assembly ability, which are the key poin...

  3. Synthetic Astrobiology

    Science.gov (United States)

    Rothschild, Lynn J.

    2016-01-01

    Synthetic biology - the design and construction of new biological parts and systems and the redesign of existing ones for useful purposes - has the potential to transform fields from pharmaceuticals to fuels. Our lab has focused on the potential of synthetic biology to revolutionize all three major parts of astrobiology: Where do we come from? Where are we going? and Are we alone? For the first and third, synthetic biology is allowing us to answer whether the evolutionary narrative that has played out on planet earth is likely to have been unique or universal. For example, in our lab we are re-evolving the biosynthetic pathways of amino acids in order to understand potential capabilities of an early organism with a limited repertoire of amino acids and developing techniques for the recovery of metals from spent electronics on other planetary bodies. And what about the limits for life? Can we create organisms that expand the envelope for life? In the future synthetic biology will play an increasing role in human activities both on earth, in fields as diverse as human health and the industrial production of novel bio-composites. Beyond earth, we will rely increasingly on biologically-provided life support, as we have throughout our evolutionary history. In order to do this, the field will build on two of the great contributions of astrobiology: studies of the origin of life and life in extreme environments.

  4. Heart Attack Recovery FAQs

    Science.gov (United States)

    ... smolder — that can be destructive. If you think counseling would help your family deal with your heart attack more ... your lifestyle habits through exercise training, education and counseling to ... or with the help of your doctor, nurse, dietitian or other healthcare ...

  5. Fatal crocodile attack.

    Science.gov (United States)

    Chattopadhyay, Saurabh; Shee, Biplab; Sukul, Biswajit

    2013-11-01

    Attacks on human beings by various animals leading to varied types of injuries and even death in some cases are not uncommon. Crocodile attacks on humans have been reported from a number of countries across the globe. Deaths in such attacks are mostly due to mechanical injuries or drowning. Bites by the crocodiles often cause the limbs to be separated from the body. The present case refers to an incident of a fatal attack by a crocodile on a 35 years old female where only the mutilated head of the female was recovered. Multiple lacerated wounds over the face and scalp along with fracture of the cranial bones was detected on autopsy. Two distinct bite marks in the form of punched in holes were noted over the parietal and frontal bones. Injuries on the head with its traumatic amputation from the body were sufficient to cause death. However, the presence of other fatal injuries on the unrecovered body parts could not be ruled out. Copyright © 2013 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  6. Temporal Cyber Attack Detection.

    Energy Technology Data Exchange (ETDEWEB)

    Ingram, Joey Burton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Draelos, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Galiardi, Meghan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Doak, Justin E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-01

    Rigorous characterization of the performance and generalization ability of cyber defense systems is extremely difficult, making it hard to gauge uncertainty, and thus, confidence. This difficulty largely stems from a lack of labeled attack data that fully explores the potential adversarial space. Currently, performance of cyber defense systems is typically evaluated in a qualitative manner by manually inspecting the results of the system on live data and adjusting as needed. Additionally, machine learning has shown promise in deriving models that automatically learn indicators of compromise that are more robust than analyst-derived detectors. However, to generate these models, most algorithms require large amounts of labeled data (i.e., examples of attacks). Algorithms that do not require annotated data to derive models are similarly at a disadvantage, because labeled data is still necessary when evaluating performance. In this work, we explore the use of temporal generative models to learn cyber attack graph representations and automatically generate data for experimentation and evaluation. Training and evaluating cyber systems and machine learning models requires significant, annotated data, which is typically collected and labeled by hand for one-off experiments. Automatically generating such data helps derive/evaluate detection models and ensures reproducibility of results. Experimentally, we demonstrate the efficacy of generative sequence analysis techniques on learning the structure of attack graphs, based on a realistic example. These derived models can then be used to generate more data. Additionally, we provide a roadmap for future research efforts in this area.

  7. BIRD ATTACK OCULAR INJURIES.

    Science.gov (United States)

    Tabatabaei, Seyed Ali; Soleimani, Mohammad; Behrouz, Mahmoud Jabbarvand

    2017-03-29

    To report 30 patients with bird attack-related eye injuries. This study was performed among patients coming to Farabi Eye Hospital, Tehran, Iran, from 2010 to 2015 with a history of bird attack causing eye injury. The inclusion criteria were a history of bird attack by pecking causing eye injury and having treatment and follow-up record for at least 6 months after treatment. The primary eye examinations included a full ophthalmic examination including evaluation of uncorrected visual acuity and best-corrected visual acuity (BCVA), anterior segment slit lamp biomicroscopy, and photography. For all patients with penetrating injury, primary repair was undertaken. Thirty patients (10 females and 20 males) with a mean age of 23.3 ± 18.5 years entered the study. The most common zone of injury was zone 1 (P < 0.001), and lensectomy was not needed in majority of patients (P < 0.001). The most common bird causing the injury was mynah (P < 0.001). Those patients with baseline BCVA of less than 20/200 or those with endophthalmitis had statistically worse final BCVA after treatment. Patients attacked by mynah bird had significantly better pretreatment uncorrected visual acuity and BCVA. The most common bird causing the eye injury among the sample of patients from Iran was mynah, which differs with previous studies indicating the rooster attack as the most common cause of eye injury. The authors also found that the most common zone of injury was zone 1, and the presence of endophthalmitis and lower baseline BCVA were significant risk factors for worse visual outcomes.

  8. Bluetooth security attacks comparative analysis, attacks, and countermeasures

    CERN Document Server

    Haataja, Keijo; Pasanen, Sanna; Toivanen, Pekka

    2013-01-01

    This overview of Bluetooth security examines network vulnerabilities and offers a comparative analysis of recent security attacks. It also examines related countermeasures and proposes a novel attack that works against all existing Bluetooth versions.

  9. Challenges in polymer analysis by liquid chromatography

    NARCIS (Netherlands)

    Uliyanchenko, E.; van der Wal, S.; Schoenmakers, P.J.

    2012-01-01

    Synthetic polymers are very important in our daily life. Many valuable properties of polymers are determined by their molecular weight and chemical composition. Liquid chromatographic (LC) techniques are very commonly used for molecular characterisation of polymers. LC analysis of macromolecules is

  10. Polymer chemistry: Not lost in translation

    Science.gov (United States)

    O'Reilly, Rachel K.

    2013-04-01

    Strategies for making sequence-controlled polymers in the laboratory are really quite primitive in comparison with those used in nature. By combining concepts from natural systems and synthetic polymer chemistry, it has now been shown that DNA codes can be translated into non-nucleic-acid polymers with defined sequences.

  11. A new biotechnology for articular cartilage repair: subchondral implantation of a composite of interconnected porous hydroxyapatite, synthetic polymer (PLA-PEG), and bone morphogenetic protein-2 (rhBMP-2).

    Science.gov (United States)

    Tamai, Noriyuki; Myoui, Akira; Hirao, Makoto; Kaito, Takashi; Ochi, Takahiro; Tanaka, Junzo; Takaoka, Kunio; Yoshikawa, Hideki

    2005-05-01

    Articular cartilage repair remains a major obstacle in tissue engineering. We recently developed a novel tool for articular cartilage repair, consisting of a triple composite of an interconnected porous hydroxyapatite (IP-CHA), recombinant human bone morphogenetic protein-2 (rhBMP-2), and a synthetic biodegradable polymer [poly-d,l-lactic acid/polyethylene glycol (PLA-PEG)] as a carrier for rhBMP-2. In the present study, we evaluated the capacity of the triple composite to induce the regeneration of articular cartilage. Full-thickness cartilage defects were created in the trochlear groove of 52 New Zealand White rabbits. Sixteen defects were filled with the bone morphogenetic protein (BMP)/PLA-PEG/IP-CHA composite (group I), 12 with PLA-PEG/IP-CHA (group II), 12 with IP-CHA alone (group III), and 12 were left empty (group IV). The animals were killed 1, 3, and 6 weeks after surgery, and the gross appearance of the defect sites was assessed. The harvested tissues were examined radiographically and histologically. One week after implantation with the BMP/PLA-PEG/IP-CHA composite (group I), vigorous repair had occurred in the subchondral defect. It contained an agglomeration of mesenchymal cells which had migrated from the surrounding bone marrow either directly, or indirectly via the interconnecting pores of the IP-CHA scaffold. At 6 weeks, these defects were completely repaired. The regenerated cartilage manifested a hyaline-like appearance, with a mature matrix and a columnar organization of chondrocytes. The triple composite of rhBMP-2, PLA-PEG, and IP-CHA promotes the repair of full-thickness articular cartilage defects within as short a period as 3 weeks in the rabbit model. Hence, this novel cell-free implant biotechnology could mark a new development in the field of articular cartilage repair.

  12. BIOCHEMICAL DEGRADATION OF POLYMERS.

    Science.gov (United States)

    It is the object of the article to review the specific hydrolytic, redox, and electron transfer reactions involving enzymes and their mechanisms...The stability of the synthetic high polymers in the biochemical environments is much higher than that of proteins in general, but the increasing use of

  13. Life After a Heart Attack

    Science.gov (United States)

    ... been stable for a few weeks. Anxiety and Depression After a Heart Attack After a heart attack, ... 2009, this project provided six awards at five academic institutions to identify genetic connections to heart, lung, ...

  14. When women attack.

    Science.gov (United States)

    McLaughlin, Bryan; Davis, Catasha; Coppini, David; Kim, Young Mie; Knisely, Sandra; McLeod, Douglas

    2015-01-01

    The common assumption that female candidates on the campaign trail should not go on the attack, because such tactics contradict gender stereotypes, has not received consistent support. We argue that in some circumstances gender stereotypes will favor female politicians going negative. To test this proposition, this study examines how gender cues affect voter reactions to negative ads in the context of a political sex scandal, a context that should prime gender stereotypes that favor females. Using an online experiment involving a national sample of U.S. adults (N = 599), we manipulate the gender and partisan affiliation of a politician who attacks a male opponent caught in a sex scandal involving sexually suggestive texting to a female intern. Results show that in the context of a sex scandal, a female candidate going on the attack is evaluated more positively than a male. Moreover, while female participants viewed the female sponsor more favorably, sponsor gender had no effect on male participants. Partisanship also influenced candidate evaluations: the Democratic female candidate was evaluated more favorably than her Republican female counterpart.

  15. Attack Trees with Sequential Conjunction

    NARCIS (Netherlands)

    Jhawar, Ravi; Kordy, Barbara; Mauw, Sjouke; Radomirović, Sasa; Trujillo-Rasua, Rolando

    2015-01-01

    We provide the first formal foundation of SAND attack trees which are a popular extension of the well-known attack trees. The SAND at- tack tree formalism increases the expressivity of attack trees by intro- ducing the sequential conjunctive operator SAND. This operator enables the modeling of

  16. Replacement Attack: A New Zero Text Watermarking Attack

    Science.gov (United States)

    Bashardoost, Morteza; Mohd Rahim, Mohd Shafry; Saba, Tanzila; Rehman, Amjad

    2017-03-01

    The main objective of zero watermarking methods that are suggested for the authentication of textual properties is to increase the fragility of produced watermarks against tampering attacks. On the other hand, zero watermarking attacks intend to alter the contents of document without changing the watermark. In this paper, the Replacement attack is proposed, which focuses on maintaining the location of the words in the document. The proposed text watermarking attack is specifically effective on watermarking approaches that exploit words' transition in the document. The evaluation outcomes prove that tested word-based method are unable to detect the existence of replacement attack in the document. Moreover, the comparison results show that the size of Replacement attack is estimated less accurate than other common types of zero text watermarking attacks.

  17. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    Directory of Open Access Journals (Sweden)

    Yi-Hsun Wang

    2010-09-01

    Full Text Available Web applications suffer from cross-site scripting (XSS attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of generating mutated XSS attacks in a fully automatic way. Mutated XSS attack generation depends on the analysis of attack vectors and the structural learning mechanism. For the kernel of the learning mechanism, we use a Hidden Markov model (HMM as the structure of the attack vector model to capture the implicit manner of the attack vector, and this manner is benefited from the syntax meanings that are labeled by the proposed tokenizing mechanism. Bayes theorem is used to determine the number of hidden states in the model for generalizing the structure model. The paper has the contributions as following: (1 automatically learn the structure of attack vectors from practical data analysis to modeling a structure model of attack vectors, (2 mimic the manners and the elements of attack vectors to extend the ability of testing tool for identifying XSS vulnerabilities, (3 be helpful to verify the flaws of blacklist sanitization procedures of Web applications. We evaluated the proposed mechanism by Burp Intruder with a dataset collected from public XSS archives. The results show that mutated XSS attack generation can identify potential vulnerabilities.

  18. Seven Deadliest Unified Communications Attacks

    CERN Document Server

    York, Dan

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting Unified Communications technology? Then you need Seven Deadliest Unified Communication Attacks. This book pinpoints the most dangerous hacks and exploits specific to Unified Communications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks featured in this book include: UC Ecosystem Attacks Insecure Endpo

  19. Natural - synthetic - artificial!

    DEFF Research Database (Denmark)

    Nielsen, Peter E

    2010-01-01

    The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life.......The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life....

  20. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  1. Synthetic Cannabinoids.

    Science.gov (United States)

    Mills, Brooke; Yepes, Andres; Nugent, Kenneth

    2015-07-01

    Synthetic cannabinoids (SCBs), also known under the brand names of "Spice," "K2," "herbal incense," "Cloud 9," "Mojo" and many others, are becoming a large public health concern due not only to their increasing use but also to their unpredictable toxicity and abuse potential. There are many types of SCBs, each having a unique binding affinity for cannabinoid receptors. Although both Δ-tetrahydrocannabinol (THC) and SCBs stimulate the same receptors, cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2), studies have shown that SCBs are associated with higher rates of toxicity and hospital admissions than is natural cannabis. This is likely due to SCBs being direct agonists of the cannabinoid receptors, whereas THC is a partial agonist. Furthermore, the different chemical structures of SCBs found in Spice or K2 may interact in unpredictable ways to elicit previously unknown, and the commercial products may have unknown contaminants. The largest group of users is men in their 20s who participate in polydrug use. The most common reported toxicities with SCB use based on studies using Texas Poison Control records are tachycardia, agitation and irritability, drowsiness, hallucinations, delusions, hypertension, nausea, confusion, dizziness, vertigo and chest pain. Acute kidney injury has also been strongly associated with SCB use. Treatment mostly involves symptom management and supportive care. More research is needed to identify which contaminants are typically found in synthetic marijuana and to understand the interactions between different SBCs to better predict adverse health outcomes.

  2. Synthetic chromosomes.

    Science.gov (United States)

    Schindler, Daniel; Waldminghaus, Torsten

    2015-11-01

    What a living organism looks like and how it works and what are its components-all this is encoded on DNA, the genetic blueprint. Consequently, the way to change an organism is to change its genetic information. Since the first pieces of recombinant DNA have been used to transform cells in the 1970s, this approach has been enormously extended. Bigger and bigger parts of the genetic information have been exchanged or added over the years. Now we are at a point where the construction of entire chromosomes becomes a reachable goal and first examples appear. This development leads to fundamental new questions, for example, about what is possible and desirable to build or what construction rules one needs to follow when building synthetic chromosomes. Here we review the recent progress in the field, discuss current challenges and speculate on the appearance of future synthetic chromosomes. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Coupling of Active Components to Synthetic Polymers

    DEFF Research Database (Denmark)

    Overgaard, Anne Kathrine Kattenhøj

    Arbejdet har fokuseret på fremstilling af kunstig ekstracellulær matrix (ECM) til fremme af den naturlige biologiske helingsproces ved vævsgendannelse efter store vævsskader. Særlig opmærksomhed har været på kemisk kobling af dermatan sulfat (DS), en naturlig glyco-saminoglycan (GAG), med en biok...

  4. aminophenol on synthetic polymer-fibres

    African Journals Online (AJOL)

    DJFLEX

    Edward Arnold (Pub.) Ltd: London. Anna, U., Eva, B., Janka, O., Randovan, T. and Anton,. M., 2007. Dyes and pigment, 72(2): 212 – 216. Bird, C. L. and Boston, W. S., 1975. The Theory of. Coloration of Textiles. SDC: Bradford. Giles, C. H., 1974. Laboratory course in Dyeing, SDC: Bradford, 139. Kan, C. W., Chan K, Yuen, ...

  5. Integration of Natural Polymers and Synthetic Nanostructures

    Science.gov (United States)

    2014-11-20

    better than anything reported to date (Figure) are potentially useful in nanosensors, microencapsulation , and protective coatings. One-pot laminate...Sci., 2014, 39, 1934-1972. 3. I. Drachuk, M. K. Gupta, V. V. Tsukruk, Biomimetic coatings to control cellular function through cell surface...Drachuk, R. Calabrese, D. L. Kaplan, V. V. Tsukruk, Inkjet printing of silk nest arrays for cell hosting, Biomacromolecules, 2014, 15, 1428-1435. 4

  6. The Mechanisms of Biodegradation of Synthetic Polymers

    Science.gov (United States)

    1989-02-17

    following permeation chromatography . Even when the enzyme was concentrated by ultrafiltration, purified by gel permeation chromatography , and...demonstrate any cell-associated enzyme by preparing protoplasts and looking fur activity on the protoplast . The findings with Crvntococcus indicate that the...extracellularly. When subjected to gel permeation chromatography three peaks of activity were seen. We are presently evaluating these peaks to determine

  7. Metal analysis from synthetic polymer matrix

    OpenAIRE

    Myllyperkiö, Minna

    2016-01-01

    Vain tiivistelmä. Opinnäytteiden arkistokappaleet ovat luettavissa Helsingin yliopiston kirjastossa. Hae HELKA-tietokannasta (http://www.helsinki.fi/helka/index.htm). Abstract only. The paper copy of the whole thesis is available for reading room use at the Helsinki University Library. Search HELKA online catalog (http://www.helsinki.fi/helka/index.htm). Endast avhandlingens sammandrag. Pappersexemplaret av hela avhandlingen finns för läsesalsbruk i Helsingfors universitets bibliotek. S...

  8. Attacks on computer systems

    Directory of Open Access Journals (Sweden)

    Dejan V. Vuletić

    2012-01-01

    Full Text Available Computer systems are a critical component of the human society in the 21st century. Economic sector, defense, security, energy, telecommunications, industrial production, finance and other vital infrastructure depend on computer systems that operate at local, national or global scales. A particular problem is that, due to the rapid development of ICT and the unstoppable growth of its application in all spheres of the human society, their vulnerability and exposure to very serious potential dangers increase. This paper analyzes some typical attacks on computer systems.

  9. Routing of individual polymers in designed patterns

    DEFF Research Database (Denmark)

    Knudsen, Jakob Bach; Liu, Lei; Kodal, Anne Louise Bank

    2015-01-01

    Synthetic polymers are ubiquitous in the modern world, but our ability to exert control over the molecular conformation of individual polymers is very limited. In particular, although the programmable self-assembly of oligonucleotides and proteins into artificial nanostructures has been...... demonstrated, we currently lack the tools to handle other types of synthetic polymers individually and thus the ability to utilize and study their single-molecule properties. Here we show that synthetic polymer wires containing short oligonucleotides that extend from each repeat can be made to assemble...... into arbitrary routings. The wires, which can be more than 200 nm in length, are soft and bendable, and the DNA strands allow individual polymers to self-assemble into predesigned routings on both two- and three-dimensional DNA origami templates. The polymers are conjugated and potentially conducting, and could...

  10. Can You Recognize a Heart Attack? Quiz

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Can You Recognize a Heart Attack? Updated:Sep 16, ... a Heart Attack Heart Attack Symptoms in Women “Can you recognize a heart attack?” Quiz • Understand Your ...

  11. Synthetic Botany.

    Science.gov (United States)

    Boehm, Christian R; Pollak, Bernardo; Purswani, Nuri; Patron, Nicola; Haseloff, Jim

    2017-07-05

    Plants are attractive platforms for synthetic biology and metabolic engineering. Plants' modular and plastic body plans, capacity for photosynthesis, extensive secondary metabolism, and agronomic systems for large-scale production make them ideal targets for genetic reprogramming. However, efforts in this area have been constrained by slow growth, long life cycles, the requirement for specialized facilities, a paucity of efficient tools for genetic manipulation, and the complexity of multicellularity. There is a need for better experimental and theoretical frameworks to understand the way genetic networks, cellular populations, and tissue-wide physical processes interact at different scales. We highlight new approaches to the DNA-based manipulation of plants and the use of advanced quantitative imaging techniques in simple plant models such as Marchantia polymorpha. These offer the prospects of improved understanding of plant dynamics and new approaches to rational engineering of plant traits. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

  12. Synthetic wisdom.

    Science.gov (United States)

    Kitcher, Philip

    2016-11-01

    Wisdom is a special kind of virtue. It is not to be identified with any outstanding cognitive ability-like having a prodigious memory or knowing a lot. Rather it consists in seeing what is most important and most valuable, either within a particular domain or in life as a whole. In the life of a wise person, that insight should be accompanied by traits of character, enabling the person to pursue what is seen as valuable. Viewing wisdom as a capacity for synthetic understanding, I argue for the need for philosophy, even at a time when all of us have much to learn from the sciences. © 2016 New York Academy of Sciences.

  13. Synthetic Brainbows

    KAUST Repository

    Wan, Y.

    2013-06-01

    Brainbow is a genetic engineering technique that randomly colorizes cells. Biological samples processed with this technique and imaged with confocal microscopy have distinctive colors for individual cells. Complex cellular structures can then be easily visualized. However, the complexity of the Brainbow technique limits its applications. In practice, most confocal microscopy scans use different florescence staining with typically at most three distinct cellular structures. These structures are often packed and obscure each other in rendered images making analysis difficult. In this paper, we leverage a process known as GPU framebuffer feedback loops to synthesize Brainbow-like images. In addition, we incorporate ID shuffing and Monte-Carlo sampling into our technique, so that it can be applied to single-channel confocal microscopy data. The synthesized Brainbow images are presented to domain experts with positive feedback. A user survey demonstrates that our synthetic Brainbow technique improves visualizations of volume data with complex structures for biologists.

  14. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira

    2015-09-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

  15. Recent "phishing" attacks

    CERN Multimedia

    IT Department

    2009-01-01

    Over the last few weeks there has been a marked increase in the number of attacks on CERN made by cybercriminals. Typical attacks arrive in the form of e-mail messages purporting to come from the CERN Help Desk, Mail Service, or some similarly official-sounding entity and suggest that there is a problem with your account, such as it being over-quota. They then ask you to click on a link or to reply and give your password. Please don’t! Be cautious of any unexpected messages containing web links even if they appear to come from known contacts. If you happen to click on such a link and if your permission is requested to run or install software, always decline it. NEVER provide your password or other details if these are requested. These messages try to trick you into clicking on Web links which will help them to install malicious software on your computer, and anti-virus software cannot be relied on to detect all cases. In case of questions on this topic, you may contact mailto:helpdesk@cern.ch. CERN Comput...

  16. Dendritic Polymers for Theranostics.

    Science.gov (United States)

    Ma, Yuan; Mou, Quanbing; Wang, Dali; Zhu, Xinyuan; Yan, Deyue

    2016-01-01

    Dendritic polymers are highly branched polymers with controllable structures, which possess a large population of terminal functional groups, low solution or melt viscosity, and good solubility. Their size, degree of branching and functionality can be adjusted and controlled through the synthetic procedures. These tunable structures correspond to application-related properties, such as biodegradability, biocompatibility, stimuli-responsiveness and self-assembly ability, which are the key points for theranostic applications, including chemotherapeutic theranostics, biotherapeutic theranostics, phototherapeutic theranostics, radiotherapeutic theranostics and combined therapeutic theranostics. Up to now, significant progress has been made for the dendritic polymers in solving some of the fundamental and technical questions toward their theranostic applications. In this review, we briefly summarize how to control the structures of dendritic polymers, the theranostics-related properties derived from their structures and their theranostics-related applications.

  17. Polymers for Protein Conjugation

    Directory of Open Access Journals (Sweden)

    Gianfranco Pasut

    2014-01-01

    Full Text Available Polyethylene glycol (PEG at the moment is considered the leading polymer for protein conjugation in view of its unique properties, as well as to its low toxicity in humans, qualities which have been confirmed by its extensive use in clinical practice. Other polymers that are safe, biodegradable and custom-designed have, nevertheless, also been investigated as potential candidates for protein conjugation. This review will focus on natural polymers and synthetic linear polymers that have been used for protein delivery and the results associated with their use. Genetic fusion approaches for the preparation of protein-polypeptide conjugates will be also reviewed and compared with the best known chemical conjugation ones.

  18. Mechanical Properties of Polymer Concrete

    Directory of Open Access Journals (Sweden)

    Raman Bedi

    2013-01-01

    Full Text Available Polymer concrete was introduced in the late 1950s and became well known in the 1970s for its use in repair, thin overlays and floors, and precast components. Because of its properties like high compressive strength, fast curing, high specific strength, and resistance to chemical attacks polymer concrete has found application in very specialized domains. Simultaneously these materials have been used in machine construction also where the vibration damping property of polymer concrete has been exploited. This review deals with the efforts of various researchers in selection of ingredients, processing parameters, curing conditions, and their effects on the mechanical properties of the resulting material.

  19. Cyber Attacks and Combat Behavior

    Directory of Open Access Journals (Sweden)

    Carataș Maria Alina

    2017-01-01

    Full Text Available Cyber terrorism is an intangible danger, a real over the corner threat in the life of individuals,organizations, and governments and is getting harder to deal with its damages. The motivations forthe cyber-attacks are different, depending on the terrorist group, from cybercrime to hacktivism,attacks over the authorities’ servers. Organizations constantly need to find new ways ofstrengthening protection against cyber-attacks, assess their cyber readiness, expand the resiliencecapacity and adopts international security regulations.

  20. Tracing Technique for Blaster Attack

    OpenAIRE

    S., Siti Rahayu; Y., Robiah; S., Shahrin; A., Faizal M.; M, Mohd Zaki; R, Irda

    2009-01-01

    Blaster worm of 2003 is still persistent, the infection appears to have successfully transitioned to new hosts as the original systems are cleaned or shut off, suggesting that the Blaster worm, and other similar worms, will remain significant Internet threats for many years after their initial release. This paper is to propose technique on tracing the Blaster attack from various logs in different OSI layers based on fingerprint of Blaster attack on victim logs, attacker logs and IDS alert log...

  1. Attacks on RFID Identification Systems

    Directory of Open Access Journals (Sweden)

    D. M. Mikhaylov

    2010-09-01

    Full Text Available This article is about attacks on RFID systems. Currently antivirus developers are not developing systems that protect from viruses that could exist on RFID tags. Such viruses are considered as not existing because the RFID tag memory is very small. Unfortunately such viruses exist. This article is concerned to such viruses and attacks that hackers could do using such viruses. Based on this article methods to prevent RFID-viruses attacks could be developed.

  2. Cell-free biology: exploiting the interface between synthetic biology and synthetic chemistry.

    Science.gov (United States)

    Harris, D Calvin; Jewett, Michael C

    2012-10-01

    Just as synthetic organic chemistry once revolutionized the ability of chemists to build molecules (including those that did not exist in nature) following a basic set of design rules, cell-free synthetic biology is beginning to provide an improved toolbox and faster process for not only harnessing but also expanding the chemistry of life. At the interface between chemistry and biology, research in cell-free synthetic systems is proceeding in two different directions: using synthetic biology for synthetic chemistry and using synthetic chemistry to reprogram or mimic biology. In the coming years, the impact of advances inspired by these approaches will make possible the synthesis of nonbiological polymers having new backbone compositions, new chemical properties, new structures, and new functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Seven Deadliest Social Network Attacks

    CERN Document Server

    Timm, Carl

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting social networks? Then you need Seven Deadliest Social Network Attacks. This book pinpoints the most dangerous hacks and exploits specific to social networks like Facebook, Twitter, and MySpace, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Social Networking Infrastruct

  4. Seven Deadliest Web Application Attacks

    CERN Document Server

    Shema, Mike

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting web applications? Then you need Seven Deadliest Web Application Attacks. This book pinpoints the most dangerous hacks and exploits specific to web applications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. .. .. Attacks detailed in this book include: ..: ..; Cross-Site Scripting (XSS) ..; Cross-Site Request Fo

  5. Synthetic Nanovaccines Against Respiratory Pathogens (SYNARP)

    Science.gov (United States)

    2012-07-01

    develop fully synthetic vaccines against respiratory infections using novel nanotechnology platforms based on safe and degradable adjuvant polymer...polyanhydride nanospheres (BPN) carrying a polypeptide/protein antigen (Platform A); b) polymeric micelles of Pluronic block copolymer as DNA vaccine adjuvant ...subcutaneously and intranasally (10 µg dose) with and without different traditional adjuvants : monophosphoryl lipid A (MPLA) or aluminum salts (Alum) (Table 1

  6. Attacker profiling in quantitative security assessment based on attack trees

    NARCIS (Netherlands)

    Lenin, Aleksandr; Willemson, Jan; Sari, Dyan Permata

    2014-01-01

    We present the results of research of limiting adversarial budget in attack games, and, in particular, in the failure-free attack tree models presented by Buldas-Stepanenko in 2012 and improved in 2013 by Buldas and Lenin. In the previously presented models attacker’s budget was assumed to be

  7. Synthetic biology: applications come of age.

    Science.gov (United States)

    Khalil, Ahmad S; Collins, James J

    2010-05-01

    Synthetic biology is bringing together engineers and biologists to design and build novel biomolecular components, networks and pathways, and to use these constructs to rewire and reprogram organisms. These re-engineered organisms will change our lives over the coming years, leading to cheaper drugs, 'green' means to fuel our cars and targeted therapies for attacking 'superbugs' and diseases, such as cancer. The de novo engineering of genetic circuits, biological modules and synthetic pathways is beginning to address these crucial problems and is being used in related practical applications.

  8. DNA meets synthetic polymers—highly versatile hybrid materials

    NARCIS (Netherlands)

    Alemdaroglu, Fikri E.; Herrmann, Andreas

    2007-01-01

    The combination of synthetic polymers and DNA has provided biologists, chemists and materials scientists with a fascinating new hybrid material. The challenges in preparing these molecular chimeras were overcome by different synthetic strategies that rely on coupling the nucleic acid moiety and the

  9. Invisible Trojan-horse attack

    DEFF Research Database (Denmark)

    Sajeed, Shihan; Minshull, Carter; Jain, Nitin

    2017-01-01

    We demonstrate the experimental feasibility of a Trojan-horse attack that remains nearly invisible to the single-photon detectors employed in practical quantum key distribution (QKD) systems, such as Clavis2 from ID Quantique. We perform a detailed numerical comparison of the attack performance...

  10. Heart Attack Symptoms in Women

    Science.gov (United States)

    ... and Conditions and Privacy Policy Go Red For Women® presents: View our first-ever short film (opens in new window) by Elizabeth Banks and share with the women you love. Heart Attack • Home • About Heart Attacks ...

  11. [Heart-attack in pregnancy].

    Science.gov (United States)

    Výtisková, T; Suchá, D; Fučíková, Z

    To describe hear-attack on crystal meth addicted pregnant woman. Case report. Acute heart-attack during pregnancy means unexpected obstetric complication. The consequences could be fatal for the mother and the fetus. Although good delivery management and treatment could reduce morbidity and mortality to a minimum.

  12. Effect of synthetic modifiers on the rheology of coating colours

    OpenAIRE

    Laine, Jaana

    2015-01-01

    The effect of synthetic modifiers on the coating colour rheology was studied. Also the influence of the pigment system was studied. Six different polymers were studied in two pigment systems. In the solely ground calcium carbonate (GCC)-containing formulation polymers were studied with three different addition levels. GCC/clay-based formulation was tested with one polymer addition level in order to study rheology; water retention, Brookfield viscosity and Hercules high shear were measured. ...

  13. Invisible Trojan-horse attack.

    Science.gov (United States)

    Sajeed, Shihan; Minshull, Carter; Jain, Nitin; Makarov, Vadim

    2017-08-21

    We demonstrate the experimental feasibility of a Trojan-horse attack that remains nearly invisible to the single-photon detectors employed in practical quantum key distribution (QKD) systems, such as Clavis2 from ID Quantique. We perform a detailed numerical comparison of the attack performance against Scarani-Ac´ın-Ribordy-Gisin (SARG04) QKD protocol at 1924 nm versus that at 1536 nm. The attack strategy was proposed earlier but found to be unsuccessful at the latter wavelength, as reported in N. Jain et al., New J. Phys. 16, 123030 (2014). However at 1924 nm, we show experimentally that the noise response of the detectors to bright pulses is greatly reduced, and show by modeling that the same attack will succeed. The invisible nature of the attack poses a threat to the security of practical QKD if proper countermeasures are not adopted.

  14. Superposition Attacks on Cryptographic Protocols

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Funder, Jakob Løvstad; Nielsen, Jesper Buus

    2011-01-01

    string model. While our protocol is classical, it is sound against a cheating unbounded quantum prover and computational zero-knowledge even if the verifier is allowed a superposition attack. Finally, we consider multiparty computation and show that for the most general type of attack, simulation based......Attacks on classical cryptographic protocols are usually modeled by allowing an adversary to ask queries from an oracle. Security is then defined by requiring that as long as the queries satisfy some constraint, there is some problem the adversary cannot solve, such as compute a certain piece...... of information. In this paper, we introduce a fundamentally new model of quantum attacks on classical cryptographic protocols, where the adversary is allowed to ask several classical queries in quantum superposition. This is a strictly stronger attack than the standard one, and we consider the security...

  15. Biosynthetic Polymers as Functional Materials

    OpenAIRE

    Carlini, Andrea S.; Adamiak, Lisa; Gianneschi, Nathan C.

    2016-01-01

    The synthesis of functional polymers encoded with biomolecules has been an extensive area of research for decades. As such, a diverse toolbox of polymerization techniques and bioconjugation methods has been developed. The greatest impact of this work has been in biomedicine and biotechnology, where fully synthetic and naturally derived biomolecules are used cooperatively. Despite significant improvements in biocompatible and functionally diverse polymers, our success in the field is constrain...

  16. 77 FR 12508 - Schedules of Controlled Substances: Placement of Five Synthetic Cannabinoids Into Schedule I

    Science.gov (United States)

    2012-03-01

    ... of individuals exposed to synthetic cannabinoids with symptoms that include anxiety and panic attacks... addiction or dependence. 8. Whether the Substance is an Immediate Precursor of a Substance Already...

  17. Allergens might trigger migraine attacks.

    Science.gov (United States)

    Bektas, Hesna; Karabulut, Hayriye; Doganay, Beyza; Acar, Baran

    2017-03-01

    Migraine is a common primary headache disorder. The mechanisms underlying the onset of a migraine attack are not completely understood. Environmental changes and a number of other factors could induce migraine attacks. The aim of this study was to investigate the relationship between the frequency of migraine attacks and allergens. Migraine patients without aura, and healthy individuals similar in age and gender without a history of headache and allergy were prospectively included in the study. The duration of migraine, the frequency of migraine attacks, the medication history, and the symptoms during attacks were questioned. Migraine disability assessment score (MIDAS) and visual analog scale (VAS) scores were obtained. Allergen extracts including dust, fungi, insect, animal epithelium, pollens, and food allergens were applied for allergy tests. 49 migraine patients and 49 healthy individuals were enrolled in the study. There was no significant difference in terms of age and gender. The median migraine disease duration, the number of attacks in a month, and the duration of attacks were, respectively, 5.5 years (1-44), 4 (1-10) day/month, and 24 (4-72) h. The mean MIDAS grade was 2.45 ± 0.14 (1-4), and mean VAS score was 7.89 ± 0.27 (4-10). The positivity of allergy tests was 55.1 % (27/49) in the migraine group and 32.7 % (16/49) in the control group (p < 0.05). The allergy tests were positive for house dust, red birch, hazel tree, olive tree, nettle, and wheat. The frequency of migraine attacks was higher in allergy-test-positive patients than in negative ones in the migraine group (p = 0.001). The migraine patients who had frequent attacks should be examined for allergies.

  18. WILD PIG ATTACKS ON HUMANS

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, J.

    2013-04-12

    Attacks on humans by wild pigs (Sus scrofa) have been documented since ancient times. However, studies characterizing these incidents are lacking. In an effort to better understand this phenomenon, information was collected from 412 wild pig attacks on humans. Similar to studies of large predator attacks on humans, data came from a variety of sources. The various attacks compiled occurred in seven zoogeographic realms. Most attacks occurred within the species native range, and specifically in rural areas. The occurrence was highest during the winter months and daylight hours. Most happened under non-hunting circumstances and appeared to be unprovoked. Wounded animals were the chief cause of these attacks in hunting situations. The animals involved were typically solitary, male and large in size. The fate of the wild pigs involved in these attacks varied depending upon the circumstances, however, most escaped uninjured. Most human victims were adult males traveling on foot and alone. The most frequent outcome for these victims was physical contact/mauling. The severity of resulting injuries ranged from minor to fatal. Most of the mauled victims had injuries to only one part of their bodies, with legs/feet being the most frequent body part injured. Injuries were primarily in the form of lacerations and punctures. Fatalities were typically due to blood loss. In some cases, serious infections or toxemia resulted from the injuries. Other species (i.e., pets and livestock) were also accompanying some of the humans during these attacks. The fates of these animals varied from escaping uninjured to being killed. Frequency data on both non-hunting and hunting incidents of wild pig attacks on humans at the Savannah River Site, South Carolina, showed quantitatively that such incidents are rare.

  19. Shark Attack Project - Marine Attack at Towed Hydrophone Arrays

    National Research Council Canada - National Science Library

    Kalmijn, Adrianus J

    2005-01-01

    The original objective of the SIO Marine Attack project was to identify the electric and magnetic fields causing sharks to inflict serious damage upon the towed hydrophone arrays of US Navy submarines...

  20. Multiculturalism & The Charlie Hebdo Attack

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2016-01-01

    The attack on Charlie Hebdo has by many been linked to multiculturalism. But it is unclear exactly how the connection between multiculturalism and the attack should be understood and whether there indeed is such a connection. The article discusses this by distinguishing between different senses...... of multiculturalism and different ways in which one might think that there is a link between multiculturalism and the attack. On this basis the resulting claims are discussed as to whether they are in fact plausible, which many of them turn out not to be....

  1. Automated Generation of Attack Trees

    DEFF Research Database (Denmark)

    Vigo, Roberto; Nielson, Flemming; Nielson, Hanne Riis

    2014-01-01

    -prone and impracticable for large systems. Nonetheless, the automated generation of attack trees has only been explored in connection to computer networks and levering rich models, whose analysis typically leads to an exponential blow-up of the state space. We propose a static analysis approach where attack trees...... interesting quantitative problems, that can be solved through an encoding into Satisfiability Modulo Theories. The flexibility and effectiveness of the approach is demonstrated on the study of a national-scale authentication system, whose attack tree is computed thanks to a Java implementation...

  2. The Cyber-Physical Attacker

    DEFF Research Database (Denmark)

    Vigo, Roberto

    2012-01-01

    The world of Cyber-Physical Systems ranges from industrial to national interest applications. Even though these systems are pervading our everyday life, we are still far from fully understanding their security properties. Devising a suitable attacker model is a crucial element when studying...... the security properties of CPSs, as a system cannot be secured without defining the threats it is subject to. In this work an attacker scenario is presented which addresses the peculiarities of a cyber-physical adversary, and we discuss how this scenario relates to other attacker models popular in the security...

  3. Low band gap polymers for organic photovoltaics

    DEFF Research Database (Denmark)

    Bundgaard, Eva; Krebs, Frederik C

    2007-01-01

    Low band gap polymer materials and their application in organic photovoltaics (OPV) are reviewed. We detail the synthetic approaches to low band gap polymer materials starting from the early methodologies employing quinoid homopolymer structures to the current state of the art that relies...

  4. Some legal challenges posed by remote attack

    National Research Council Canada - National Science Library

    William Boothby

    2012-01-01

      Abstract Attacking from a distance is nothing new, but with the advent of certain new technologies, attacks can be undertaken in which the attacker remains very remote from the scene where force will be employed...

  5. Social Engineering Attack Detection Model: SEADMv2

    CSIR Research Space (South Africa)

    Mouton, F

    2015-10-01

    Full Text Available and is only able to cater for social engineering attacks that use bidirectional communication. Previous research discovered that social engineering attacks can be classified into three different categories, namely attacks that utilise bidirectional...

  6. Active Polymer Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2010-01-01

    Full Text Available Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a wormlike motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.

  7. Polymer Nanocomposites

    Indian Academy of Sciences (India)

    The synthesis of polymer nanocomposites is an integral aspect of polymer nanotechnology. By inserting the nano- metric inorganic compounds, the properties of polymers improve and hence this has a lot of applications depending upon the inorganic material present in the polymers. Sol- vent casting is one of the easiest ...

  8. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  9. Genetic attack on neural cryptography.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Naeh, Rivka; Kanter, Ido

    2006-03-01

    Different scaling properties for the complexity of bidirectional synchronization and unidirectional learning are essential for the security of neural cryptography. Incrementing the synaptic depth of the networks increases the synchronization time only polynomially, but the success of the geometric attack is reduced exponentially and it clearly fails in the limit of infinite synaptic depth. This method is improved by adding a genetic algorithm, which selects the fittest neural networks. The probability of a successful genetic attack is calculated for different model parameters using numerical simulations. The results show that scaling laws observed in the case of other attacks hold for the improved algorithm, too. The number of networks needed for an effective attack grows exponentially with increasing synaptic depth. In addition, finite-size effects caused by Hebbian and anti-Hebbian learning are analyzed. These learning rules converge to the random walk rule if the synaptic depth is small compared to the square root of the system size.

  10. What Causes a Heart Attack?

    Science.gov (United States)

    ... heart attack at age 36, it stopped her "dead in her tracks." Jennifer reminds us how heart disease takes too many of our moms, sisters, and friends from us every day. The more we share our stories, the faster ...

  11. What Is a Heart Attack?

    Science.gov (United States)

    ... blood pressure and excess protein in the urine. Preeclampsia is linked to an increased lifetime risk of heart disease, including CHD, heart attack, heart failure , and high blood pressure. Screening and Prevention Lowering your risk factors for coronary heart disease ...

  12. CAS, interdiction, and attack helicopters

    OpenAIRE

    Groenke, Andrew S.

    2005-01-01

    Within days of a major failed strike by attack helicopters during Operation Iraqi Freedom (OIF) analysts were questioning the value of such platforms on the modern battlefield. As OIF moved from combat to stability operations, helicopter losses from enemy action actually increased seemingly strengthening the argument of those who see the helicopter as unsuitable to some combat operations. Attack helicopter operations have diverged into two distinct categories, interdiction and close air sup...

  13. Software-based Microarchitectural Attacks

    OpenAIRE

    Gruss, Daniel

    2017-01-01

    Modern processors are highly optimized systems where every single cycle of computation time matters. Many optimizations depend on the data that is being processed. Software-based microarchitectural attacks exploit effects of these optimizations. Microarchitectural side-channel attacks leak secrets from cryptographic computations, from general purpose computations, or from the kernel. This leakage even persists across all common isolation boundaries, such as processes, containers, and virtual ...

  14. Controlled release from recombinant polymers.

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-09-28

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Controlled Release from Recombinant Polymers

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  16. Synthetic biology of microbes synthesizing polyhydroxyalkanoates (PHA

    Directory of Open Access Journals (Sweden)

    Guo-Qiang Chen

    2016-12-01

    Full Text Available Microbial polyhydroxyalkanoates (PHA have been produced as bioplastics for various purposes. Under the support of China National Basic Research 973 Project, we developed synthetic biology methods to diversify the PHA structures into homo-, random, block polymers with improved properties to better meet various application requirements. At the same time, various pathways were assembled to produce various PHA from glucose as a simple carbon source. At the end, Halomonas bacteria were reconstructed to produce PHA in changing morphology for low cost production under unsterile and continuous conditions. The synthetic biology will advance the PHA into a bio- and material industry.

  17. Polymer Directed Protein Assemblies

    Directory of Open Access Journals (Sweden)

    Patrick van Rijn

    2013-05-01

    Full Text Available Protein aggregation and protein self-assembly is an important occurrence in natural systems, and is in some form or other dictated by biopolymers. Very obvious influences of biopolymers on protein assemblies are, e.g., virus particles. Viruses are a multi-protein assembly of which the morphology is dictated by poly-nucleotides namely RNA or DNA. This “biopolymer” directs the proteins and imposes limitations on the structure like the length or diameter of the particle. Not only do these bionanoparticles use polymer-directed self-assembly, also processes like amyloid formation are in a way a result of directed protein assembly by partial unfolded/misfolded biopolymers namely, polypeptides. The combination of proteins and synthetic polymers, inspired by the natural processes, are therefore regarded as a highly promising area of research. Directed protein assembly is versatile with respect to the possible interactions which brings together the protein and polymer, e.g., electrostatic, v.d. Waals forces or covalent conjugation, and possible combinations are numerous due to the large amounts of different polymers and proteins available. The protein-polymer interacting behavior and overall morphology is envisioned to aid in clarifying protein-protein interactions and are thought to entail some interesting new functions and properties which will ultimately lead to novel bio-hybrid materials.

  18. A computer network attack taxonomy and ontology

    CSIR Research Space (South Africa)

    Van Heerden, RP

    2012-01-01

    Full Text Available of attacks, means that an attack could be mitigated accordingly. The authors extend a previous, initial taxonomy of computer network attacks which forms the basis of a proposed network attack ontology in this paper. The objective of this ontology...

  19. Analytical Characterization of Internet Security Attacks

    Science.gov (United States)

    Sellke, Sarah H.

    2010-01-01

    Internet security attacks have drawn significant attention due to their enormously adverse impact. These attacks includes Malware (Viruses, Worms, Trojan Horse), Denial of Service, Packet Sniffer, and Password Attacks. There is an increasing need to provide adequate defense mechanisms against these attacks. My thesis proposal deals with analytical…

  20. Time-dependent analysis of attacks

    NARCIS (Netherlands)

    Arnold, Florian; Hermanns, H.; Pulungan, Reza; Stoelinga, Mariëlle Ida Antoinette

    The success of a security attack crucially depends on time: the more time available to the attacker, the higher the probability of a successful attack; when given enough time, any system can be compromised. Insight in time-dependent behaviors of attacks and the evolution of the attacker’s success as

  1. RESIST SRP AGAINST WORMHOLE ATTACK

    Directory of Open Access Journals (Sweden)

    Marjan Kuchaki Rafsanjani

    2013-06-01

    Full Text Available Ad-hoc networks refer to temporary or interim networks which form for special purposes. Actually they are wireless networks with mobile nodes. These networks use no network assisting element for path routing and in these networks available nodes are responsible for path routing. Therefore when malicious nodes want to find a way to interfere with the path routing then the existence of a secure route protocol (SRP can prevent the interference. SRP protocol is one of the secure algorithms of path routing protocol but it is notresistant against wormhole attack. Wormhole attack is considered as a subtle attack in which two malicious nodes make a short connection in network's topology through private or implicit connection and represent two non neighbor nodes as neighbors and prevent the correctoperation of path routing protocol by using this method. One of the methods of preventing wormhole attack is by using packet leashes. We try to decrease the wormhole attack occurrence in this routing protocol by a kind of packet leashes called temporal leashes. We alsowill minimize problems resulting from using temporal leashes by different methods and modifications in its structure.

  2. Plant synthetic biology.

    Science.gov (United States)

    Liu, Wusheng; Stewart, C Neal

    2015-05-01

    Plant synthetic biology is an emerging field that combines engineering principles with plant biology toward the design and production of new devices. This emerging field should play an important role in future agriculture for traditional crop improvement, but also in enabling novel bioproduction in plants. In this review we discuss the design cycles of synthetic biology as well as key engineering principles, genetic parts, and computational tools that can be utilized in plant synthetic biology. Some pioneering examples are offered as a demonstration of how synthetic biology can be used to modify plants for specific purposes. These include synthetic sensors, synthetic metabolic pathways, and synthetic genomes. We also speculate about the future of synthetic biology of plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Network robustness under large-scale attacks

    CERN Document Server

    Zhou, Qing; Liu, Ruifang; Cui, Shuguang

    2014-01-01

    Network Robustness under Large-Scale Attacks provides the analysis of network robustness under attacks, with a focus on large-scale correlated physical attacks. The book begins with a thorough overview of the latest research and techniques to analyze the network responses to different types of attacks over various network topologies and connection models. It then introduces a new large-scale physical attack model coined as area attack, under which a new network robustness measure is introduced and applied to study the network responses. With this book, readers will learn the necessary tools to evaluate how a complex network responds to random and possibly correlated attacks.

  4. Hydrolysis of synthetic mixed-acid phosphatides by phospholipase A from human pancreas

    NARCIS (Netherlands)

    Deenen, L.L.M. van; Haas, Gerard H. de; Heemskerk, C.H.Th.

    1963-01-01

    An investigation was made into the action of a human pancreatic phospholipase A on various synthetic phosphatides. L-α-Phosphatidyl ethanolamines were readily hydrolysed in an aqueous system by this enzyme. Synthetic lecithins, however, were not attacked in an appreciable rate by the mammalian

  5. Polymers, Polymers, Everywhere! A Workshop for Pre-High School Teachers and Students.

    Science.gov (United States)

    Sherman, Marie

    1987-01-01

    Described is a workshop for grades 5-8 school teachers and students related to synthetic polymers. Participants become familiar with polymer theory and practice experiments they can use in class. Sources of materials used in the workshop are listed. (RH)

  6. Sulfated Polysaccharides and a Synthetic Sulfated Polymer Are Potent Inhibitors of Chlamydia trachomatis Infectivity In Vitro but Lack Protective Efficacy in an In Vivo Murine Model of Chlamydial Genital Tract Infection

    Science.gov (United States)

    Su, Hua; Caldwell, Harlan D.

    1998-01-01

    Heparin, dextran sulfate, pentosan polysulfate, and a sulfated synthetic copolymer of acrylic acid and vinyl alcohol were shown to be potent inhibitors of Chlamydia trachomatis infectivity for cultured human epithelial cells. Despite their potent antichlamydial activity in vitro, neither heparin nor dextran sulfate was effective in inhibiting the infectivity of C. trachomatis in a murine model of chlamydial infection of the female genital tract. PMID:9488423

  7. Carbon nanotube-based synthetic gecko tapes

    OpenAIRE

    Ge, Liehui; Sethi, Sunny; Ci, Lijie; Ajayan, Pulickel M.; Dhinojwala, Ali

    2007-01-01

    We have developed a synthetic gecko tape by transferring micropatterned carbon nanotube arrays onto flexible polymer tape based on the hierarchical structure found on the foot of a gecko lizard. The gecko tape can support a shear stress (36 N/cm2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micrometer-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscop...

  8. PHOTOREFRACTIVE POLYMERS

    NARCIS (Netherlands)

    Morichere, D; Malliaras, G.G; Krasnikov, V.V.; Bolink, H.J; Hadziioannou, G

    The use of polymers as photorefractive materials offers many advantages : flexibility in synthesis, doping, processing and low cost. The required functionalities responsible for photorefractivity, namely charge generation, transport, trapping and linear electrooptic effect are given in the polymer

  9. Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers; Desenvolvimento de espumas parcialmente biodegradaveis a partir de blendas de PP/HMSPP com polimeros naturais e sinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Elizabeth Carvalho Leite

    2014-07-01

    Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

  10. Polymer and polymer-hybrid nanoparticles from synthesis to biomedical applications

    CERN Document Server

    Rangelov, Stanislav

    2013-01-01

    Polymeric and hybrid nanoparticles have received increased scientific interest in terms of basic research as well as commercial applications, promising a variety of uses for nanostructures in fields including bionanotechnology and medicine. Condensing the relevant research into a comprehensive reference, Polymer and Polymer-Hybrid Nanoparticles: From Synthesis to Biomedical Applications covers an array of topics from synthetic procedures and macromolecular design to possible biomedical applications of nanoparticles and materials based on original and unique polymers. The book presents a well-r

  11. Identifying Vulnerabilities and Hardening Attack Graphs for Networked Systems

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Sudip; Vullinati, Anil K.; Halappanavar, Mahantesh; Chatterjee, Samrat

    2016-09-15

    We investigate efficient security control methods for protecting against vulnerabilities in networked systems. A large number of interdependent vulnerabilities typically exist in the computing nodes of a cyber-system; as vulnerabilities get exploited, starting from low level ones, they open up the doors to more critical vulnerabilities. These cannot be understood just by a topological analysis of the network, and we use the attack graph abstraction of Dewri et al. to study these problems. In contrast to earlier approaches based on heuristics and evolutionary algorithms, we study rigorous methods for quantifying the inherent vulnerability and hardening cost for the system. We develop algorithms with provable approximation guarantees, and evaluate them for real and synthetic attack graphs.

  12. Mitigating Higher Ed Cyber Attacks

    Science.gov (United States)

    Rogers, Gary; Ashford, Tina

    2015-01-01

    In this presentation we will discuss the many and varied cyber attacks that have recently occurred in the higher ed community. We will discuss the perpetrators, the victims, the impact and how these institutions have evolved to meet this threat. Mitigation techniques and defense strategies will be covered as will a discussion of effective security…

  13. Television Journalism During Terror Attacks

    DEFF Research Database (Denmark)

    Mogensen, Kirsten

    This article views television news coverage of ongoing terrorist attacks and their immediate aftermath as a special genre within journalism, and describes norms connected with the genre. The description is based on qualitative analyses of the coverage on the major American networks in the fi rst 24...

  14. Television journalism during terror attacks

    DEFF Research Database (Denmark)

    Mogensen, Kirsten

    2008-01-01

    This article views television news coverage of ongoing terrorist attacks and their immediate aftermath as a special genre within journalism, and describes norms connected with the genre. The description is based on qualitative analyses of the coverage on major American networks the first 24 hours...

  15. The Timing of Terrorist Attacks

    DEFF Research Database (Denmark)

    Jensen, Thomas

    2016-01-01

    I use a simple optimal stopping model to derive policy relevant insights on the timing of one-shot attacks by small autonomous terrorist units or “lone wolf” individuals. A main insight is that an increase in proactive counterterrorism measures can lead to a short term increase in the number...

  16. Sequence Programmable Peptoid Polymers for Diverse Materials Applications.

    Science.gov (United States)

    Knight, Abigail S; Zhou, Effie Y; Francis, Matthew B; Zuckermann, Ronald N

    2015-10-14

    Polymer sequence programmability is required for the diverse structures and complex properties that are achieved by native biological polymers, but efforts towards controlling the sequence of synthetic polymers are, by comparison, still in their infancy. Traditional polymers provide robust and chemically diverse materials, but synthetic control over their monomer sequences is limited. The modular and step-wise synthesis of peptoid polymers, on the other hand, allows for precise control over the monomer sequences, affording opportunities for these chains to fold into well-defined nanostructures. Hundreds of different side chains have been incorporated into peptoid polymers using efficient reaction chemistry, allowing for a seemingly infinite variety of possible synthetically accessible polymer sequences. Combinatorial discovery techniques have allowed the identification of functional polymers within large libraries of peptoids, and newly developed theoretical modeling tools specifically adapted for peptoids enable the future design of polymers with desired functions. Work towards controlling the three-dimensional structure of peptoids, from the conformation of the amide bond to the formation of protein-like tertiary structure, has and will continue to enable the construction of tunable and innovative nanomaterials that bridge the gap between natural and synthetic polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Conjugated Polymers for Energy Production

    DEFF Research Database (Denmark)

    Livi, Francesco

    This dissertation is aimed at developing materials for flexible, large area, ITO-free polymer solar cells (PSCs) fully printed under ambient conditions. A large screening of conjugated polymers, both novel and well-known materials, has been carried out in order to find suitable candidates...... for scalable PSCs fully printed under ambient conditions [Adv. Energy Mater. 2015, 5, 1402186]. PPDTBT resulted to be the conjugated polymer with the best photovoltaic performance within the 104 synthesized macromolecules. Therefore, further studies have been done on such material. The impact of side chain...... arylation (DAr) and direct arylation polymerization (DArP) have been applied to the preparation of PPDTBT, making this polymer readily available in only 4 synthetic steps and thus easily transferable to a large scale-production setup. DArP avoids organometallic species and therefore is an appealing...

  18. Supramolecular Polymers

    Science.gov (United States)

    Stupp, S. I.; Keser, M.; Huggins, K. E.; Tew, G.; Li, L. S.; Whitaker, C.

    1997-03-01

    An interesting target in polymer science is to find pathways to highly regular supramolecular units with dimensions similar to those of high molar mass linear or hyperbranched polymers. These units lack a polymeric backbone but could serve as precursors to shape invariant covalent polymers analogous to folded proteins. We are pursuing access to these polymers with designed molecules programmed to assemble into nanostructures of regular shape and dimension. We have discovered systems of miniaturized triblock copolymers that yield supramolecular polymers. These supramolecular polymers are shaped as mushroom nanostructures, and form materials with interesting surface and optical properties. Molecular modeling indicates that a balance of aggregation and hard core repulsive forces among structural units may be responsible for the formation of these supramolecular polymers.

  19. Trojan Horse Attacking Strategy on Quantum Cryptography

    Science.gov (United States)

    Zeng, Guihua

    2003-08-01

    Trojan horse attacking strategy on quantum cryptography is investigated, three aspects are involved. First, the mechanism for the Trojan horse attacking strategy on quantum cryptography as well as classic cryptography is studied. Then the fragility of the quantum cryptographic algorithm employing EPR pairs as key against the Trojan horse attacking strategy is analyzed. To prevent the Trojan horse attacking strategy, an improvement scheme which makes use of non-orthogonal entangled states is proposed, results show the improvement scheme is robust to the Trojan horse attacking strategy without reducing the security on other kinds of attacking strategies.

  20. Crony Attack: Strategic Attack’s Silver Bullet

    Science.gov (United States)

    2006-11-01

    by distributing a large amount of private goods to the selectorate—the cronies—can be termed kleptocracies . Many govern- ments do indeed resemble...where the high-private goods kleptocracy is a good model. Furthermore, while not an example of crony attack to affect policy change (as opposed to...information about those nearest to the leader. The relationships part is only the start. Kleptocracies , like orga- nized crime leaders, are clever

  1. Writing on polymer chains.

    Science.gov (United States)

    Lutz, Jean-François

    2013-11-19

    Synthetic polymer materials are currently limited by their inability to store information in their chains, unlike some well-characterized biopolymers. Nucleic acids store and transmit genetic information, and amino acids encode the complex tridimensional structures and functions within proteins. To confer similar properties on synthetic materials, researchers must develop"writing" mechanisms, facile chemical pathways that allow control over the primary structure of synthetic polymer chains. The most obvious way to control the primary structure is to connect monomer units one-by-one in a given order using iterative chemistry. Although such synthesis strategies are commonly used to produce peptides and nucleic acids, they produce limited yields and are much slower than natural polymerization mechanisms. An alternative strategy would be to use multiblock copolymers with blocks that have specified sequences. In this case, however, the basic storage element is not a single molecular unit, but a longer block composed of several repeating units. However, the synthesis of multiblock copolymers is long and tedious. Therefore, researchers will need to develop other strategies for writing information onto polymer chains. In this Account, I describe our recent progress in the development of sequence controlled polymerization methods. Although our research focuses on different strategies, we have emphasized sequence-regulation in chain-growth polymerization processes. Chain-growth polymerizations, particularly radical polymerization, are very convenient methods for synthesizing polymers. However, in most cases, such approaches do not lead to controlled monomer sequences. During the last five years, we have shown that controlled/living chain-growth polymerization mechanisms offer interesting advantages for sequence regulation. In such mechanisms, the chains form gradually over time, and therefore the primary structure can be tuned by using time-controlled monomer additions. For

  2. Modeling synthetic lethality

    OpenAIRE

    Le Meur, Nolwenn; Gentleman, Robert

    2008-01-01

    Background Synthetic lethality defines a genetic interaction where the combination of mutations in two or more genes leads to cell death. The implications of synthetic lethal screens have been discussed in the context of drug development as synthetic lethal pairs could be used to selectively kill cancer cells, but leave normal cells relatively unharmed. A challenge is to assess genome-wide experimental data and integrate the results to better understand the underlying biological processes. We...

  3. Evolvable synthetic neural system

    Science.gov (United States)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  4. Nanoscale Study of Polymer Dynamics.

    Science.gov (United States)

    Keshavarz, Masoumeh; Engelkamp, Hans; Xu, Jialiang; Braeken, Els; Otten, Matthijs B J; Uji-I, Hiroshi; Schwartz, Erik; Koepf, Matthieu; Vananroye, Anja; Vermant, Jan; Nolte, Roeland J M; De Schryver, Frans; Maan, Jan C; Hofkens, Johan; Christianen, Peter C M; Rowan, Alan E

    2016-01-26

    The thermal motion of polymer chains in a crowded environment is anisotropic and highly confined. Whereas theoretical and experimental progress has been made, typically only indirect evidence of polymer dynamics is obtained either from scattering or mechanical response. Toward a complete understanding of the complicated polymer dynamics in crowded media such as biological cells, it is of great importance to unravel the role of heterogeneity and molecular individualism. In the present work, we investigate the dynamics of synthetic polymers and the tube-like motion of individual chains using time-resolved fluorescence microscopy. A single fluorescently labeled polymer molecule is observed in a sea of unlabeled polymers, giving access to not only the dynamics of the probe chain itself but also to that of the surrounding network. We demonstrate that it is possible to extract the characteristic time constants and length scales in one experiment, providing a detailed understanding of polymer dynamics at the single chain level. The quantitative agreement with bulk rheology measurements is promising for using local probes to study heterogeneity in complex, crowded systems.

  5. Synthetic cornea: biocompatibility and optics

    Science.gov (United States)

    Parel, Jean-Marie A.; Kaminski, Stefan; Fernandez, Viviana; Alfonso, E.; Lamar, Peggy; Lacombe, Emmanuel; Duchesne, Bernard; Dubovy, Sander; Manns, Fabrice; Rol, Pascal O.

    2002-06-01

    Purpose. Experimentally find a method to provide a safe surgical technique and an inexpensive and long lasting mesoplant for the restoration of vision in patients with bilateral corneal blindness due to ocular surface and stromal diseases. Methods. Identify the least invasive and the safest surgical technique for synthetic cornea implantation. Identify the most compatible biomaterials and the optimal shape a synthetic cornea must have to last a long time when implanted in vivo. Results. Penetrating procedures were deemed too invasive, time consuming, difficult and prone to long term complications. Therefore a non-penetrating delamination technique with central trephination was developed to preserve the integrity of Descemet's membrane and the anterior segment. Even though this approach limits the number of indications, it is acceptable since the majority of patients only have opacities in the stroma. The prosthesis was designed to fit in the removed tissue plane with its skirt fitted under the delaminated stroma. To improve retention, the trephination wall was made conical with the smallest opening on the anterior surface and a hat-shaped mesoplant was made to fit. The skirt was perforated in its perimeter to allow passage of nutrients and tissues ingrowths. To simplify the fabrication procedure, the haptic and optic were made of the same polymer. The intrastromal biocompatibility of several hydrogels was found superior to current clinically used PMMA and PTFE materials. Monobloc mesoplants made of 4 different materials were implanted in rabbits and followed weekly until extrusion occurred. Some remained optically clear allowing for fundus photography. Conclusions. Hydrogel synthetic corneas can be made to survive for periods longer than 1 year. ArF excimer laser photoablation studies are needed to determine the refractive correction potential of these mesoplants. A pilot FDA clinical trial is needed to assess the mesoplant efficacy and very long-term stability.

  6. Timing Is Everything with Heart Attacks

    Science.gov (United States)

    ... and certain time periods. The study was published online recently in the American Heart Journal . Previous research has suggested that highly stressful events, such as earthquakes and World Cup soccer games, may trigger heart attacks. Stress-related heart attacks ...

  7. Stochastic Model of TCP SYN Attacks

    Directory of Open Access Journals (Sweden)

    Simona Ramanauskaitė

    2011-08-01

    Full Text Available A great proportion of essential services are moving into internet space making the threat of DoS attacks even more actual. To estimate the real risk of some kind of denial of service (DoS attack in real world is difficult, but mathematical and software models make this task easier. In this paper we overview the ways of implementing DoS attack models and offer a stochastic model of SYN flooding attack. It allows evaluating the potential threat of SYN flooding attacks, taking into account both the legitimate system flow as well as the possible attack power. At the same time we can assess the effect of such parameters as buffer capacity, open connection storage in the buffer or filte­ring efficiency on the success of different SYN flooding attacks. This model can be used for other type of memory depletion denial of service attacks.Article in Lithuanian

  8. Lifestyle Changes for Heart Attack Prevention

    Science.gov (United States)

    ... help prevent your first heart attack. Heart-Healthy Lifestyle Changes A heart-healthy lifestyle can help prevent ... to flow to the heart muscle. Heart-Healthy Lifestyle Changes Treatment for a heart attack usually includes ...

  9. Social engineering attack examples, templates and scenarios

    CSIR Research Space (South Africa)

    Mouton, Francois

    2016-06-01

    Full Text Available link. A social engineering attack targets this weakness by using various manipulation techniques to elicit sensitive information. The field of social engineering is still in its early stages with regard to formal definitions, attack frameworks...

  10. Being active after a heart attack (image)

    Science.gov (United States)

    ... best activity when you start exercising after a heart attack. Start slowly, and increase the amount of time ... best activity when you start exercising after a heart attack. Start slowly, and increase the amount of time ...

  11. Synthetic Cathinones ("Bath Salts")

    Science.gov (United States)

    ... Viral) HIV/AIDS Mental Health Military Opioid Overdose Reversal with Naloxone (Narcan, Evzio) Pain Prevention Recovery Substance ... seem real but are not increased friendliness increased sex drive panic attacks excited delirium—extreme agitation and ...

  12. [From synthetic biology to synthetic humankind].

    Science.gov (United States)

    Nouvel, Pascal

    2015-01-01

    In this paper, we propose an historical survey of the expression "synthetic biology" in order to identify its main philosophical components. The result of the analysis is then used to investigate the meaning of the notion of "synthetic man". It is shown that both notions share a common philosophical background that can be summed up by the short but meaningful assertion: "biology is technology". The analysis allows us to distinguish two notions that are often confused in transhumanist literature: the notion of synthetic man and the notion of renewed man. The consequences of this crucial distinction are discussed. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  13. Intermittent hypoendorphinaemia in migraine attack.

    Science.gov (United States)

    Baldi, E; Salmon, S; Anselmi, B; Spillantini, M G; Cappelli, G; Brocchi, A; Sicuteri, F

    1982-06-01

    Beta-endorphin (RIA method, previous chromatographic extraction) was evaluated in plasma of migraine sufferers in free periods and during attacks. Decreased levels of the endogenous opioid peptide were found in plasma sampled during the attacks but not in free periods. Even chronic headache sufferers exhibited significantly lowered levels of beta-endorphin, when compared with control subjects with a negative personal and family history of head pains. The mechanism of the hypoendorphinaemia is unknown: lowered levels of the neuropeptide, which controls nociception, vegetative functions and hedonia, could be important in a syndrome such as migraine, characterized by pain, dysautonomia and anhedonia. The impairment of monoaminergic synapses ("empty neuron" condition) constantly present in sufferers from serious headaches, could be due to the fact that opioid neuropeptides, because of a receptoral or metabolic impairment, poorly modulate the respective monoaminergic neurons, resulting in imbalance of synaptic neurotransmission.

  14. Liquid crystalline order in polymers

    CERN Document Server

    Blumstein, Alexandre

    1978-01-01

    Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

  15. Network Attack Reference Data Set

    Science.gov (United States)

    2004-12-01

    fingerprinting tools include QueSO [10] (literally translates to “what OS”) and nmap [11], however there are a number of additional tools available for...Network Attack Reference Data Set J. McKenna and J. Treurniet Defence R&D Canada √ Ottawa TECHNICAL...collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources

  16. Joint Direct Attack Munition (JDAM)

    Science.gov (United States)

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-503 Joint Direct Attack Munition (JDAM) As of FY 2017 President’s Budget Defense Acquisition...Mission and Description 6 Executive Summary 7 Threshold Breaches 8 Schedule 9 Performance 12 Track to Budget 14 Cost and Funding...15 Low Rate Initial Production 26 Foreign Military Sales 27 Nuclear Costs 29 Unit Cost 30 Cost Variance 33 Contracts 36

  17. Dual Stage SQL Injection Attacks

    OpenAIRE

    Eve, Martin Paul

    2009-01-01

    I came across quite an interesting SQL Injection scenario today. The software in which the vulnerability resides will remain anonymous until fixed, but an abstracted version of the scenario can safely be outlined below.\\ud \\ud The objective of the software is to restrict user accounts to certain IP addresses when accessing a bulletin board. This shows how this can be bypassed using a dual-stage SQL injection attack.

  18. New Multi-step Worm Attack Model

    OpenAIRE

    Robiah, Y.; Rahayu, S. Siti; Shahrin, S.; Faizal, M. A.; Zaki, M. Mohd; Marliza, R.

    2010-01-01

    The traditional worms such as Blaster, Code Red, Slammer and Sasser, are still infecting vulnerable machines on the internet. They will remain as significant threats due to their fast spreading nature on the internet. Various traditional worms attack pattern has been analyzed from various logs at different OSI layers such as victim logs, attacker logs and IDS alert log. These worms attack pattern can be abstracted to form worms' attack model which describes the process of worms' infection. Fo...

  19. Classifying network attack scenarios using an ontology

    CSIR Research Space (South Africa)

    Van Heerden, RP

    2012-03-01

    Full Text Available ). ?Spear Phishing? refers to targeted social engineering-type email attacks (Jagatic, 2007). ?Physical? refers to manual methods to gain access, for example physically removing the hard drive or breaking the access door to enter a secure server room... the size and utility of the target. The "Target" class is the physical device or entity targeted by an attack. The "Vulnerability" class describes a target vulnerability used by the attacker. The "Phase" class represents an attack model that subdivides...

  20. Terror attacks influence driving behavior in Israel

    Science.gov (United States)

    Stecklov, Guy; Goldstein, Joshua R.

    2004-01-01

    Terror attacks in Israel produce a temporary lull in light accidents followed by a 35% spike in fatal accidents on Israeli roads 3 days after the attack. Our results are based on time-series analysis of Israeli traffic flows, accidents, and terror attacks from January 2001 through June 2002. Whereas prior studies have focused on subjective reports of posttraumatic stress, our study shows a population-level behavioral response to violent terror attacks. PMID:15448203

  1. Attack Graph Construction for Security Events Analysis

    Directory of Open Access Journals (Sweden)

    Andrey Alexeevich Chechulin

    2014-09-01

    Full Text Available The paper is devoted to investigation of the attack graphs construction and analysis task for a network security evaluation and real-time security event processing. Main object of this research is the attack modeling process. The paper contains the description of attack graphs building, modifying and analysis technique as well as overview of implemented prototype for network security analysis based on attack graph approach.

  2. Distance hijacking attacks on distance bounding protocols

    OpenAIRE

    Cremers, Cas; Rasmussen, Kasper Bonne; Čapkun, Srdjan

    2011-01-01

    Distance bounding protocols are typically analyzed with respect to three types of attacks: Distance Fraud, Mafia Fraud, and Terrorist Fraud. We define a fourth main type of attacks on distance bounding protocols, called Distance Hijacking attacks. We show that many proposed distance bounding protocols are vulnerable to these attacks, and we propose solutions to make these protocols resilient to Distance Hijacking. Additionally, we generalize Distance Hijacking to Location Hijacking, to which ...

  3. Nacre-mimetics with synthetic nanoclays up to ultrahigh aspect ratios

    National Research Council Canada - National Science Library

    Das, Paramita; Malho, Jani-Markus; Rahimi, Khosrow; Schacher, Felix H; Wang, Baochun; Demco, Dan Eugen; Walther, Andreas

    2015-01-01

    .... Here we demonstrate large progress of mechanical and functional properties of self-assembled polymer/nanoclay nacre-mimetics by using synthetic nanoclays with aspect ratios covering three orders in magnitude (25-3,500...

  4. Polymer Electrolytes

    Science.gov (United States)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  5. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  6. Cyberprints: Identifying Cyber Attackers by Feature Analysis

    Science.gov (United States)

    Blakely, Benjamin A.

    2012-01-01

    The problem of attributing cyber attacks is one of increasing importance. Without a solid method of demonstrating the origin of a cyber attack, any attempts to deter would-be cyber attackers are wasted. Existing methods of attribution make unfounded assumptions about the environment in which they will operate: omniscience (the ability to gather,…

  7. Attack Tree Generation by Policy Invalidation

    DEFF Research Database (Denmark)

    Ivanova, Marieta Georgieva; Probst, Christian W.; Hansen, Rene Rydhof

    2015-01-01

    through brainstorming of experts. In this work we formalize attack tree generation including human factors; based on recent advances in system models we develop a technique to identify possible attacks analytically, including technical and human factors. Our systematic attack generation is based...

  8. Attacks and countermeasures on AES and ECC

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2013-01-01

    AES (Advanced Encryption Standard) is widely used in LTE and Wi-Fi communication systems. AES has recently been exposed to new attacks which have questioned the overall security of AES. The newest attack is a so called biclique attack, which is using the fact that the content of the state array...

  9. Automated classification of computer network attacks

    CSIR Research Space (South Africa)

    Van Heerden, R

    2013-11-01

    Full Text Available In this paper we demonstrate how an automated reasoner, HermiT, is used to classify instances of computer network based attacks in conjunction with a network attack ontology. The ontology describes different types of network attacks through classes...

  10. 47 CFR 76.1612 - Personal attack.

    Science.gov (United States)

    2010-10-01

    ... CABLE TELEVISION SERVICE Notices § 76.1612 Personal attack. (a) When, during origination cablecasting of issues of public importance, an attack is made upon the honesty, character, integrity, or like personal... 47 Telecommunication 4 2010-10-01 2010-10-01 false Personal attack. 76.1612 Section 76.1612...

  11. Direct synthesis of nanoporous carbon nitride fibers using Al-based porous coordination polymers (Al-PCPs).

    Science.gov (United States)

    Hu, Ming; Reboul, Julien; Furukawa, Shuhei; Radhakrishnan, Logudurai; Zhang, Yuanjian; Srinivasu, Pavuluri; Iwai, Hideo; Wang, Hongjing; Nemoto, Yoshihiro; Suzuki, Norihiro; Kitagawa, Susumu; Yamauchi, Yusuke

    2011-07-28

    We report a new synthetic route for preparation of nanoporous carbon nitride fibers with graphitic carbon nitride polymers, by calcination of Al-based porous coordination polymers (Al-PCPs) with dicyandiamide (DCDA) under a nitrogen atmosphere.

  12. Polímeros sintéticos biodegradáveis: matérias-primas e métodos de produção de micropartículas para uso em drug delivery e liberação controlada Biodegradable synthetic polymers: raw-materials and production methods of microparticles for drug delivery and controlled release

    Directory of Open Access Journals (Sweden)

    Patrícia Severino

    2011-01-01

    Full Text Available Micropartículas produzidas a partir de polímeros sintéticos têm sido amplamente utilizadas na área farmacêutica para encapsulação de princípios ativos. Essas micropartículas apresentam as vantagens de proteção do princípio ativo, mucoadesão e gastrorresistência, melhor biodisponibilidade e maior adesão do paciente ao tratamento. Além disso, utiliza menores quantidade de princípio ativo para obtenção do efeito terapêutico proporcionando diminuição dos efeitos adversos locais, sistêmicos e menor toxidade. Os polímeros sintéticos empregados na produção das micropartículas são classificados biodegradáveis ou não biodegradáveis, sendo os biodegradáveis mais utilizados por não necessitam ser removidos cirurgicamente após o término de sua ação. A produção das micropartículas poliméricas sintéticas para encapsulação tanto de ativos hidrofílicos quanto hidrofóbicos pode ser emulsificação por extração e/ou evaporação do solvente; coacervação; métodos mecânicos e estão revisados neste artigo evidenciando as vantagens, desvantagens e viabilidade de cada metodologia. A escolha da metodologia e do polímero sintético a serem empregados na produção desse sistema dependem da aplicação terapêutica requerida, bem como a simplicidade, reprodutibilidade e factibilidade do aumento de escala da produção.Microparticles produced from synthetic polymers have been widely used in the pharmaceutical field for encapsulation of drugs. These microparticles show several advantages such as drug protection, mucoadhesion, gastro-resistance, improved bioavailability and increased patient's compliance. In addition, it is possible to use lower amount of drug to achieve therapeutic efficiency with reduced local/systemic adverse side effects and low toxicity. Synthetic polymers used for the production of microparticles are classified as biodegradable or non-biodegradable, being the former more popular since these do

  13. Water-Soluble Metallocene-Containing Polymers.

    Science.gov (United States)

    Alkan, Arda; Wurm, Frederik R

    2016-09-01

    Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox-activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water-soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water-soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene- and ruthenocene-containing and charged cobaltocenium-containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self-assembly behavior, and other benefits of the obtained materials are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. An Integrated Laboratory Approach toward the Preparation of Conductive Poly(phenylene vinylene) Polymers

    Science.gov (United States)

    Knoerzer, Timm A.; Balaich, Gary J.; Miller, Hannah A.; Iacono, Scott T.

    2014-01-01

    Poly(phenylene vinylene) (PPV) represents an important class of conjugated, conducting polymers that have been readily exploited in the preparation of organic electronic materials. In this experiment, students prepare a PPV polymer via a facile multistep synthetic sequence with robust spectroscopic evaluation of synthetic intermediates and the…

  15. Bio-based and recycled polymers for cleaner production : an assessment of plastics and fibres

    NARCIS (Netherlands)

    Shen, L.

    2011-01-01

    Today, almost all man-made plastics and fibres are produced from synthetic polymers. Synthetic polymers, made from petroleum which took millions of years to form, have three sustainability challenges: (i) the limited fossil fuel resources, (ii) the environmental impacts caused by non-degradable

  16. A review on introduction and applications of starch and its biodegradable polymers

    OpenAIRE

    Shanta Pokhrel

    2015-01-01

    Biodegradable polymers play a very important role in plastic engineering by replacing non biodegradable, non renewable petrol based polymers. Starch is a renewable, biodegradable, low cost natural polymer with high availability. Natural polymers can be blended with synthetic polymers to improve their properties significantly. This article reviews advance in starch and starch based blends and presents their numerous potential applications. Therefore, this review helps to understand the importa...

  17. Calculating Adversarial Risk from Attack Trees: Control Strength and Probabilistic Attackers

    NARCIS (Netherlands)

    Pieters, Wolter; Davarynejad, Mohsen

    2015-01-01

    Attack trees are a well-known formalism for quantitative analysis of cyber attacks consisting of multiple steps and alternative paths. It is possible to derive properties of the overall attacks from properties of individual steps, such as cost for the attacker and probability of success. However, in

  18. Modeling synthetic lethality.

    Science.gov (United States)

    Le Meur, Nolwenn; Gentleman, Robert

    2008-01-01

    Synthetic lethality defines a genetic interaction where the combination of mutations in two or more genes leads to cell death. The implications of synthetic lethal screens have been discussed in the context of drug development as synthetic lethal pairs could be used to selectively kill cancer cells, but leave normal cells relatively unharmed. A challenge is to assess genome-wide experimental data and integrate the results to better understand the underlying biological processes. We propose statistical and computational tools that can be used to find relationships between synthetic lethality and cellular organizational units. In Saccharomyces cerevisiae, we identified multi-protein complexes and pairs of multi-protein complexes that share an unusually high number of synthetic genetic interactions. As previously predicted, we found that synthetic lethality can arise from subunits of an essential multi-protein complex or between pairs of multi-protein complexes. Finally, using multi-protein complexes allowed us to take into account the pleiotropic nature of the gene products. Modeling synthetic lethality using current estimates of the yeast interactome is an efficient approach to disentangle some of the complex molecular interactions that drive a cell. Our model in conjunction with applied statistical methods and computational methods provides new tools to better characterize synthetic genetic interactions.

  19. Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2008-01-01

    A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective is to im...

  20. Approaches in biotechnological applications of natural polymers

    OpenAIRE

    Teixeira, José A.; Luana C.B.B. Coelho; Carneiro-da-Cunha, Maria G.; Albuquerque, Priscilla B. S.

    2016-01-01

    Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates cons...

  1. Branched polymers on branched polymers

    OpenAIRE

    Durhuus, Bergfinnur; Jonsson, Thordur

    1996-01-01

    We study an ensemble of branched polymers which are embedded on other branched polymers. This is a toy model which allows us to study explicitly the reaction of a statistical system on an underlying geometrical structure, a problem of interest in the study of the interaction of matter and quantized gravity. We find a phase transition at which the embedded polymers begin to cover the basis polymers. At the phase transition point the susceptibility exponent $\\gamma$ takes the value 3/4 and the ...

  2. Conducting Polymers

    Indian Academy of Sciences (India)

    potential of the monomer would be less than that of the dimer, which would in turn be less than that of the polymer. Hence, the polymer generated by this oxidative .... glucose and galactose biosensors based on a silicon chip employing polypyrrole have in fact been developed by several companies. These types of sensors ...

  3. Conducting Polymers

    Indian Academy of Sciences (India)

    polymer backbone), exhibit semiconducting behavior. The discovery of dopingl led to a further dramatic increase in the conductivity of such conjugated polymers to values as ..... CERF's Comments on Modem Science. • If it's incomprehensible, it's mathematics. • If it doesn't make sense, it's either economics or psychology.

  4. Polymers & People

    Science.gov (United States)

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  5. Monomer design strategies to create natural product-based polymer materials.

    Science.gov (United States)

    Kristufek, Samantha L; Wacker, Kevin T; Tsao, Yi-Yun Timothy; Su, Lu; Wooley, Karen L

    2017-04-05

    Covering: 2010-Aug. 2016In an effort towards enhancing function and sustainability, natural products have become of interest in the field of polymer chemistry. This review details the blending of chemistries developed through synthetic organic chemistry and polymer chemistry. Through synthetic organic chemical transformations, such as functional group interconversion, a protection/deprotection series, or installation of a functional group, various designs towards novel, synthetic, bio-based polymer systems are described. This review covers several classifications of natural products - oils and fatty acids, terpenes, lignin, and sugar derivatives - focusing on exploring monomers prepared by one or more synthetic steps.

  6. Whispering through DDoS attack

    Directory of Open Access Journals (Sweden)

    Miralem Mehic

    2016-03-01

    Full Text Available Denial of service (DoS attack is an attempt of the attacker to disable victim's machine by depleting network or computing resources. If this attack is performed with more than one machine, it is called distributed denial of service (DDoS attack. Covert channels are those channels which are used for information transmission even though they are neither designed nor intended to transfer information at all. In this article, we investigated the possibility of using of DDoS attack for purposes of hiding data or concealing the existing covert channel. In addition, in this paper we analyzed the possibility of detection of such covert communication with the well-known statistical method. Also, we proposed the coordination mechanisms of the attack which may be used. A lot of research has been done in order to describe and prevent DDoS attacks, yet research on steganography on this field is still scarce.

  7. Network Protection Against DDoS Attacks

    Directory of Open Access Journals (Sweden)

    Petr Dzurenda

    2015-03-01

    Full Text Available The paper deals with possibilities of the network protection against Distributed Denial of Service attacks (DDoS. The basic types of DDoS attacks and their impact on the protected network are presented here. Furthermore, we present basic detection and defense techniques thanks to which it is possible to increase resistance of the protected network or device against DDoS attacks. Moreover, we tested the ability of current commercial Intrusion Prevention Systems (IPS, especially Radware DefensePro 6.10.00 product against the most common types of DDoS attacks. We create five scenarios that are varied in type and strength of the DDoS attacks. The attacks intensity was much greater than the normal intensity of the current DDoS attacks.

  8. Surface and Bulk Modification of Synthetic Textiles to Improve Dyeability

    NARCIS (Netherlands)

    Agrawal, P. (Pramod); Parvinzadeh Gashti, M.; Willoughby, J.

    2011-01-01

    Synthetic fibers, mainly polyethylene terephthalate (PET), polyamide (PA), polyacrylonitrile (PAN) and polypropylene (PP), are the most widely used polymers in the textile industry. These fibers surpass the production of natural fibers with a market share of 54.4%. The advantages of these fibers are

  9. SQL Injection Attacks and Defense

    CERN Document Server

    Clarke, Justin

    2012-01-01

    SQL Injection Attacks and Defense, First Edition: Winner of the Best Book Bejtlich Read Award "SQL injection is probably the number one problem for any server-side application, and this book unequaled in its coverage." -Richard Bejtlich, Tao Security blog SQL injection represents one of the most dangerous and well-known, yet misunderstood, security vulnerabilities on the Internet, largely because there is no central repository of information available for penetration testers, IT security consultants and practitioners, and web/software developers to turn to for help. SQL Injection Att

  10. Coronary Artery Dissection: Not Just a Heart Attack

    Science.gov (United States)

    ... Aneurysm More Coronary Artery Dissection: Not Just a Heart Attack Updated:Oct 4,2016 Sometimes a heart attack ... Disease Go Red For Women Types of aneurysms Heart Attack • Home • About Heart Attacks Acute Coronary Syndrome (ACS) ...

  11. Synthesis of a Molecularly Imprinted Polymer for Dioxin

    Directory of Open Access Journals (Sweden)

    Magda Brattoli

    2006-08-01

    Full Text Available A molecularly imprinted polymer for recognising selectively 2,3,7,8-tetrachlorodibenzodioxin (TCDD was made by a new non-covalent method employing a“dummy” template. The proposed way represents a simplification of a synthetic schemeproposed by Lübke et al.[1] for covalent imprinting. Comparison of extraction yields of thenovel polymer, a non imprinted polymer and an imprinting polymer, prepared by theoriginal procedure demonstrates the binding capacity of the proposed polymer, which is inprinciple applicable to solid phase extraction (SPE of dioxin.

  12. BioArtificial polymers

    Science.gov (United States)

    Szałata, Kamila; Gumi, Tania

    2017-07-01

    Nowadays, the polymer science has impact in practically all life areas. Countless benefits coming from the usage of materials with high mechanical and chemical resistance, variety of functionalities and potentiality of modification drive to the development of new application fields. Novel approaches of combining these synthetic substances with biomolecules lead to obtain multifunctional hybrid conjugates which merge the bioactivity of natural component with outstanding properties of artificial polymer. Over the decades, an immense progress in bioartificial composites domain allowed to reach a high level of knowledge in terms of natural-like systems engineering, leading to diverse strategies of biomolecule immobilization. Together with different available options, including covalent and noncovalent attachment, come various challenges, related mainly with maintaining the biological activity of fixed molecules. Even though the amount of applications that achieve commercial status is still not substantial, and is expanding continuously in the disciplines like "smart materials," biosensors, delivery systems, nanoreactors and many others. A huge number of remarkable developments reported in the literature present a potential of bioartificial conjugates as a fabrics with highly controllable structure and multiple functionalities, serving as a powerful nanotechnological tool. This novel approach brings closer biologists, chemists and engineers, who sharing their effort and complementing the knowledge can revolutionize the field of bioartificial polymer science.

  13. Synthesis of regioregular pentacene-containing conjugated polymers

    KAUST Repository

    Okamoto, Toshihiro

    2011-01-01

    We report the synthesis and characterization of a new class of regioregular pentacene-containing conjugated polymers via our synthetic routes reported previously. We found that our regioregular pentacene polymers showed improved ordering than their regiorandom counterpart as well as ambipolar OFET performance. © 2011 The Royal Society of Chemistry.

  14. Synthetic cathinone abuse

    Directory of Open Access Journals (Sweden)

    Capriola M

    2013-07-01

    Full Text Available Michael Capriola Thomasville Medical Center, Thomasville, NC, USA Abstract: The abuse of synthetic cathinones, widely known as bath salts, has been increasing since the mid-2000s. These substances are derivatives of the naturally occurring compound cathinone, which is the primary psychoactive component of khat. The toxicity of synthetic cathinones includes significant sympathomimetic effects, as well as psychosis, agitation, aggression, and sometimes violent and bizarre behavior. Mephedrone and methylenedioxypyrovalerone are currently the predominantly abused synthetic cathinones. Keywords: designer drugs/chemistry, street drugs/pharmacology, substance-related disorders/epidemiology, alkaloids/poisoning

  15. Shoulder injuries from attacking motion

    Science.gov (United States)

    Yanagi, Shigeru; Nishimura, Tetsu; Itoh, Masaru; Wada, Yuhei; Watanabe, Naoki

    1997-03-01

    Sports injuries have bothered professional players. Although many medical doctors try to treat injured players, to prevent sports injuries is more important. Hence, it is required to clear a kinematic mechanism of the sport injuries. A shoulder of volleyball attacker or baseball pitcher is often inured by playing motion. The injuries are mainly caused at the end of long head tendon, which is located in the upper side of scapula. Generally, a muscle and tendon have enough strength against tensile force, however, it seems that they are sometimes defeated by the lateral force. It is imagined that the effect of the lateral force has a possibility of injuring the tendon. If we find the influence of the lateral force on the injured portion, the mechanism of injuries must be cleared. In our research, volleyball attacking motion is taken by high speed video cameras. We analyze the motion as links system and obtain an acceleration of an arm and a shoulder from video image data. The generated force at a shoulder joint is calculated and resolved into the lateral and longitudinal forces. Our final goal is to discuss a possibility that the lateral force causes the injuries.

  16. Polymers for enhanced oil recovery: fundamentals and selection criteria.

    Science.gov (United States)

    Rellegadla, Sandeep; Prajapat, Ganshyam; Agrawal, Akhil

    2017-06-01

    With a rising population, the demand for energy has increased over the years. As per the projections, both fossil fuel and renewables will remain as major energy source (678 quadrillion BTU) till 2030 with fossil fuel contributing 78% of total energy consumption. Hence, attempts are continuously made to make fossil fuel production more sustainable and cheaper. From the past 40 years, polymer flooding has been carried out in marginal oil fields and have proved to be successful in many cases. The common expectation from polymer flooding is to obtain 50% ultimate recovery with 15 to 20% incremental recovery over secondary water flooding. Both naturally derived polymers like xanthan gum and synthetic polymers like partially hydrolyzed polyacrylamide (HPAM) have been used for this purpose. Earlier laboratory and field trials revealed that salinity and temperature are the major issues with the synthetic polymers that lead to polymer degradation and adsorption on the rock surface. Microbial degradation and concentration are major issues with naturally derived polymers leading to loss of viscosity and pore throat plugging. Earlier studies also revealed that polymer flooding is successful in the fields where oil viscosity is quite higher (up to 126 cp) than injection water due to improvement in mobility ratio during polymer flooding. The largest successful polymer flood was reported in China in 1990 where both synthetic and naturally derived polymers were used in nearly 20 projects. The implementation of these projects provides valuable suggestions for further improving the available processes in future. This paper examines the selection criteria of polymer, field characteristics that support polymer floods and recommendation to design a large producing polymer flooding.

  17. MKAD Synthetic Data

    Data.gov (United States)

    National Aeronautics and Space Administration — Synthetic data used to demonstrate the effectiveness of the MKAD algorithm with respect to detecting anomalies in both the continuous numerical data and binary...

  18. Models for synthetic biology

    Directory of Open Access Journals (Sweden)

    Kaznessis Yiannis N

    2007-11-01

    Full Text Available Abstract Synthetic biological engineering is emerging from biology as a distinct discipline based on quantification. The technologies propelling synthetic biology are not new, nor is the concept of designing novel biological molecules. What is new is the emphasis on system behavior. The objective is the design and construction of new biological devices and systems to deliver useful applications. Numerous synthetic gene circuits have been created in the past decade, including bistable switches, oscillators, and logic gates, and possible applications abound, including biofuels, detectors for biochemical and chemical weapons, disease diagnosis, and gene therapies. More than fifty years after the discovery of the molecular structure of DNA, molecular biology is mature enough for real quantification that is useful for biological engineering applications, similar to the revolution in modeling in chemistry in the 1950s. With the excitement that synthetic biology is generating, the engineering and biological science communities appear remarkably willing to cross disciplinary boundaries toward a common goal.

  19. Synthetic Biology-The Synthesis of Biology.

    Science.gov (United States)

    Ausländer, Simon; Ausländer, David; Fussenegger, Martin

    2017-06-01

    Synthetic biology concerns the engineering of man-made living biomachines from standardized components that can perform predefined functions in a (self-)controlled manner. Different research strategies and interdisciplinary efforts are pursued to implement engineering principles to biology. The "top-down" strategy exploits nature's incredible diversity of existing, natural parts to construct synthetic compositions of genetic, metabolic, or signaling networks with predictable and controllable properties. This mainly application-driven approach results in living factories that produce drugs, biofuels, biomaterials, and fine chemicals, and results in living pills that are based on engineered cells with the capacity to autonomously detect and treat disease states in vivo. In contrast, the "bottom-up" strategy seeks to be independent of existing living systems by designing biological systems from scratch and synthesizing artificial biological entities not found in nature. This more knowledge-driven approach investigates the reconstruction of minimal biological systems that are capable of performing basic biological phenomena, such as self-organization, self-replication, and self-sustainability. Moreover, the syntheses of artificial biological units, such as synthetic nucleotides or amino acids, and their implementation into polymers inside living cells currently set the boundaries between natural and artificial biological systems. In particular, the in vitro design, synthesis, and transfer of complete genomes into host cells point to the future of synthetic biology: the creation of designer cells with tailored desirable properties for biomedicine and biotechnology. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Synthetic Vision Systems

    Science.gov (United States)

    Prinzel, L.J.; Kramer, L.J.

    2009-01-01

    A synthetic vision system is an aircraft cockpit display technology that presents the visual environment external to the aircraft using computer-generated imagery in a manner analogous to how it would appear to the pilot if forward visibility were not restricted. The purpose of this chapter is to review the state of synthetic vision systems, and discuss selected human factors issues that should be considered when designing such displays.

  1. Hybridization with synthetic oligonucleotides

    Energy Technology Data Exchange (ETDEWEB)

    Szostak, J.W.; Stiles, J.I.; Tye, B.K.; Sherman, F.; Wu, R.

    1978-01-01

    Procedures are described for the use of synthetic oligonucleotides for Southern blot experiments and gene bank screening, and the effect of various mismatches on the efficiency of hybridization is demonstrated. The following topics are discussed: sensitivity vs. specificity, hybridization of a 12-mer to the lambda endolysin gene; hybridization of oligonucleotide probes to the E. coli lac operator; hybridization of synthetic probes to the CYC1 gene of yeast; and cloning eucaryotic genes. (HLW)

  2. DDOS ATTACK DETECTION SIMULATION AND HANDLING MECHANISM

    Directory of Open Access Journals (Sweden)

    Ahmad Sanmorino

    2013-11-01

    Full Text Available In this study we discuss how to handle DDoS attack that coming from the attacker by using detection method and handling mechanism. Detection perform by comparing number of packets and number of flow. Whereas handling mechanism perform by limiting or drop the packets that detected as a DDoS attack. The study begins with simulation on real network, which aims to get the real traffic data. Then, dump traffic data obtained from the simulation used for detection method on our prototype system called DASHM (DDoS Attack Simulation and Handling Mechanism. From the result of experiment that has been conducted, the proposed method successfully detect DDoS attack and handle the incoming packet sent by attacker.

  3. Securing internet by eliminating DDOS attacks

    Science.gov (United States)

    Niranchana, R.; Gayathri Devi, N.; Santhi, H.; Gayathri, P.

    2017-11-01

    The major threat caused to the authorised usage of Internet is Distributed Denial of Service attack. The mechanisms used to prevent the DDoS attacks are said to overcome the attack’s ability in spoofing the IP packets source addresses. By utilising Internet Protocol spoofing, the attackers cause a consequential load over the networks destination for policing attack packets. To overcome the IP Spoofing level on the Internet, We propose an Inter domain Packet Filter (IPF) architecture. The proposed scheme is not based on global routing information. The packets with reliable source addresses are not rejected, the IPF frame work works in such a manner. The spoofing capability of attackers is confined by IPF, and also the filter identifies the source of an attack packet by minimal number of candidate network.

  4. Model checking exact cost for attack scenarios

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming

    2017-01-01

    Attack trees constitute a powerful tool for modelling security threats. Many security analyses of attack trees can be seamlessly expressed as model checking of Markov Decision Processes obtained from the attack trees, thus reaping the benefits of a coherent framework and a mature tool support....... However, current model checking does not encompass the exact cost analysis of an attack, which is standard for attack trees. Our first contribution is the logic erPCTL with cost-related operators. The extended logic allows to analyse the probability of an event satisfying given cost bounds and to compute...... the exact cost of an event. Our second contribution is the model checking algorithm for erPCTL. Finally, we apply our framework to the analysis of attack trees....

  5. Polymer flooding

    Energy Technology Data Exchange (ETDEWEB)

    Littmann, W.

    1988-01-01

    This book covers all aspects of polymer flooding, an enhanced oil recovery method using water soluble polymers to increase the viscosity of flood water, for the displacement of crude oil from porous reservoir rocks. Although this method is becoming increasingly important, there is very little literature available for the engineer wishing to embark on such a project. In the past, polymer flooding was mainly the subject of research. The results of this research are spread over a vast number of single publications, making it difficult for someone who has not kept up-to-date with developments during the last 10-15 years to judge the suitability of polymer flooding to a particular field case. This book tries to fill that gap. An indispensable book for reservoir engineers, production engineers and lab. technicians within the petroleum industry.

  6. Organometallic Polymers.

    Science.gov (United States)

    Carraher, Charles E., Jr.

    1981-01-01

    Reactions utilized to incorporate a metal-containing moiety into a polymer chain (addition, condensation, and coordination) are considered, emphasizing that these reactions also apply to smaller molecules. (JN)

  7. Thiolated polymers as mucoadhesive drug delivery systems.

    Science.gov (United States)

    Duggan, Sarah; Cummins, Wayne; O' Donovan, Orla; Hughes, Helen; Owens, Eleanor

    2017-03-30

    Mucoadhesion is the process of binding a material to the mucosal layer of the body. Utilising both natural and synthetic polymers, mucoadhesive drug delivery is a method of controlled drug release which allows for intimate contact between the polymer and a target tissue. It has the potential to increase bioavailability, decrease potential side effects and offer protection to more sensitive drugs such as proteins and peptide based drugs. The thiolation of polymers has, in the last number of years, come to the fore of mucoadhesive drug delivery, markedly improving mucoadhesion due to the introduction of free thiol groups onto the polymer backbone while also offering a more cohesive polymeric matrix for the slower and more controlled release of drug. This review explores the concept of mucoadhesion and the recent advances in both the polymers and the methods of thiolation used in the synthesis of mucoadhesive drug delivery devices. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Cell Partition in Two Polymer Aqueous Phases

    Science.gov (United States)

    Harris, J. M.

    1985-01-01

    Partition of biological cells in two phase aqueous polymer systems is recognized as a powerful separation technique which is limited by gravity. The synthesis of new, selective polymer ligand conjugates to be used in affinity partition separations is of interest. The two most commonly used polymers in two phase partitioning are dextran and polyethylene glycol. A thorough review of the chemistry of these polymers was begun, particularly in the area of protein attachment. Preliminary studies indicate the importance in affinity partitioning of minimizing gravity induced randomizing forces in the phase separation process. The PEG-protein conjugates that were prepared appear to be ideally suited for achieving high quality purifications in a microgravity environment. An interesting spin-off of this synthetic work was the observation of catalytic activity for certain of our polymer derivatives.

  9. Atomic Oxygen Erosion Yield Dependence Upon Texture Development in Polymers

    Science.gov (United States)

    Banks, Bruce A.; Loftus, Ryan J.; Miller, Sharon K.

    2016-01-01

    The atomic oxygen erosion yield (volume of a polymer that is lost due to oxidation per incident atom) of polymers is typically assumed to be reasonably constant with increasing fluence. However polymers containing ash or inorganic pigments, tend to have erosion yields that decrease with fluence due to an increasing presence of protective particles on the polymer surface. This paper investigates two additional possible causes for erosion yields of polymers that are dependent upon atomic oxygen. These are the development of surface texture which can cause the erosion yield to change with fluence due to changes in the aspect ratio of the surface texture that develops and polymer specific atomic oxygen interaction parameters. The surface texture development under directed hyperthermal attack produces higher aspect ratio surface texture than isotropic thermal energy atomic oxygen attack. The fluence dependence of erosion yields is documented for low Kapton H (DuPont, Wilmington, DE) effective fluences for a variety of polymers under directed hyperthermal and isotropic thermal energy attack.

  10. Distance hijacking attacks on distance bounding protocols

    OpenAIRE

    Cremers, Cas; Rasmussen, Kasper Bonne; Čapkun, Srdjan

    2011-01-01

    Distance bounding protocols are typically analyzed with respect to three types of attacks: Distance Fraud, Mafia Fraud, and Terrorist Fraud. We define and analyze a fourth main type of attack on distance bounding protocols, called Distance Hijacking. We show that many proposed distance bounding protocols are vulnerable to this type of attack, and we propose solutions to make these protocols resilient to Distance Hijacking. We further show that verifying distance bounding protocols using exist...

  11. Snow fall and heart attacks.

    Science.gov (United States)

    Persinger, M A; Ballance, S E; Moland, M

    1993-03-01

    Total numbers of daily hospital admissions for cardiac emergencies were obtained from 3 hospitals within the Sudbury Basin in Canada for November through March for each of 4 consecutive years (1983-1986). Major diagnostic categories were also differentiated. No statistically significant correlations were found between the amount of snowfall during the day of or the days before or after admissions for the major categories of cardiac emergency. Specific analyses, conducted to reveal possible recondite associations between extreme or cumulative snowfalls and the most extreme days of cardiac emergencies, indicated a chance association. We conclude that the occurrence of heart attacks is independent of snowfall but that, when they occur, they are attributed to shoveling if there has been a recent major snow storm.

  12. Cache timing attacks on recent microarchitectures

    DEFF Research Database (Denmark)

    Andreou, Alexandres; Bogdanov, Andrey; Tischhauser, Elmar Wolfgang

    2017-01-01

    AES or similar algorithms in virtualized environments. This paper applies variants of this cache timing attack to Intel's latest generation of microprocessors. It enables a spy-process to recover cryptographic keys, interacting with the victim processes only over TCP. The threat model is a logically...... separated but CPU co-located attacker with root privileges. We report successful and practically verified applications of this attack against a wide range of microarchitectures, from a two-core Nehalem processor (i5-650) to two-core Haswell (i7-4600M) and four-core Skylake processors (i7-6700). The attack...

  13. The Synthetic Cannabinoids Phenomenon.

    Science.gov (United States)

    Karila, Laurent; Benyamina, Amine; Blecha, Lisa; Cottencin, Olivier; Billieux, Joël

    2016-01-01

    « Spice » is generally used to describe the diverse types of herbal blends that encompass synthetic cannabinoids on the market. The emergence of smokable herbal products containing synthetic cannabinoids, which mimic the effects of cannabis, appears to become increasingly popular, in the new psychoactive substances landscape. In 2014, the existence of 134 different types of synthetic cannabinoids were reported by the European Union Early Warning System. These drugs are mainly sold online as an alternative to controlled and regulated psychoactive substances. They appear to have a life cycle of about 1-2 years before being replaced by a next wave of products. Legislation controlling these designer drugs has been introduced in many countries with the objective to limit the spread of existing drugs and control potential new analogs. The majority of the synthetic cannabinoids are full agonists at the CB1 receptor and do not contain tobacco or cannabis. They are becoming increasingly popular in adolescents, students and clubbers as an abused substance. Relatively high incidence of adverse effects associated with synthetic cannabinoids use has been documented in the literature. Numerous fatalities linked with their use and abuse have been reported. In this paper, we will review the available data regarding the use and effects of synthetic cannabinoids in humans in order to highlight their impact on public health. To reach this objective, a literature search was performed on two representative databases (Pubmed, Google Scholar), the Erowid Center website (a US non-profit educational organization that provides information about psychoactive plants and chemicals), and various governmental websites. The terms used for the database search were: "synthetic cannabinoids", "spice", "new psychoactive substances", and/or "substance use disorder", and/or "adverse effects", and/or "fatalities". The search was limited to years 2005 to 2016 due to emerging scientific literature at

  14. Identification of Successive ``Unobservable'' Cyber Data Attacks in Power Systems Through Matrix Decomposition

    Science.gov (United States)

    Gao, Pengzhi; Wang, Meng; Chow, Joe H.; Ghiocel, Scott G.; Fardanesh, Bruce; Stefopoulos, George; Razanousky, Michael P.

    2016-11-01

    This paper presents a new framework of identifying a series of cyber data attacks on power system synchrophasor measurements. We focus on detecting "unobservable" cyber data attacks that cannot be detected by any existing method that purely relies on measurements received at one time instant. Leveraging the approximate low-rank property of phasor measurement unit (PMU) data, we formulate the identification problem of successive unobservable cyber attacks as a matrix decomposition problem of a low-rank matrix plus a transformed column-sparse matrix. We propose a convex-optimization-based method and provide its theoretical guarantee in the data identification. Numerical experiments on actual PMU data from the Central New York power system and synthetic data are conducted to verify the effectiveness of the proposed method.

  15. Cued Panic Attacks in Body Dysmorphic Disorder

    Science.gov (United States)

    Phillips, Katharine A.; Menard, William; Bjornsson, Andri S.

    2013-01-01

    Background Body dysmorphic disorder (BDD) is a common and often severe disorder. Clinical observations suggest that panic attacks triggered by BDD symptoms may be common. However, to our knowledge, no study has examined such panic attacks in BDD. We investigated the prevalence, clinical features, and correlates of BDD-triggered panic attacks in individuals with this disorder. Methods Panic attacks and other variables were assessed using reliable and valid measures in 76 individuals with lifetime DSM-IV BDD. Results 28.9% (95% CI, 18.5%–39.4%) of participants reported lifetime panic attacks triggered by BDD symptoms. The most common triggers of such attacks were feeling that others were looking at or scrutinizing the perceived appearance defects (61.9%), looking in the mirror at perceived defects (38.1%), and being in bright light where perceived defects would be more visible (23.8%). The most common panic attack symptoms were palpitations (86.4%), sweating (66.7%), shortness of breath (63.6%), trembling or shaking (63.6%), and fear of losing control or going crazy (63.6%). Compared to participants without such panic attacks, those with BDD-triggered panic attacks had more severe lifetime BDD, social anxiety, and depressive symptoms, as well as poorer functioning and quality of life on a number of measures. They were also less likely to be employed and more likely to have been psychiatrically hospitalized and to have had suicidal ideation due to BDD. Conclusions Panic attacks triggered by BDD-related situations appear common in individuals with this disorder. BDD-triggered panic attacks were associated with greater symptom severity and morbidity. PMID:23653076

  16. Influence of polymer additive on flow past a hydrofoil: A numerical study

    Science.gov (United States)

    Xiong, Yongliang; Peng, Sai; Yang, Dan; Duan, Juan; Wang, Limin

    2018-01-01

    Flows of dilute polymer solutions past a hydrofoil (NACA0012) are examined by direct numerical simulation to investigate the modification of the wake pattern due to the addition of polymer. The influence of polymer additive is modeled by the FENE-P model in order to simulate a non-linear modulus of elasticity and a finite extendibility of the polymer macromolecules. Simulations were carried out at a Reynolds number of 1000 with the angle of attack varying from 0° to 20°. The results show that the influence of polymer on the flow behavior of the flow past a hydrofoil exhibits different flow regimes. In general, the addition of polymer modifies the wake patterns for all angles of attack in this study. Consequently, both drag and lift forces are changed as the Weissenberg number increases while the drag of the hydrofoil is enhanced at small angles of attack and reduced at large angles of attack. As the Weissenberg number increases, two attached recirculation bubbles or two columns of shedding vortices downstream tend to be symmetric, and the polymer tends to make the flow less sensitive to the variation of the angle of attack.

  17. Generating attacks in SysML activity diagrams by detecting attack surfaces

    NARCIS (Netherlands)

    Ouchani, Samir; Lenzini, Gabriele

    In the development process of a secure system is essential to detect as early as possible the system’s vulnerable points, the so called attack surfaces, and to estimate how feasible it would be that known attacks breach through them. Even if attack surfaces can be sometimes detected automatically,

  18. Attack Trees for Practical Security Assessment: Ranking of Attack Scenarios with ADTool 2.0

    NARCIS (Netherlands)

    Gadyatskaya, Olga; Jhawar, Ravi; Kordy, P.T.; Lounis, Karim; Mauw, Sjouke; Trujillo-Rasua, Rolando

    2016-01-01

    In this tool demonstration paper we present the ADTool2.0: an open-source software tool for design, manipulation and analysis of attack trees. The tool supports ranking of attack scenarios based on quantitative attributes entered by the user; it is scriptable; and it incorporates attack trees with

  19. British used Congreve Rockets to Attack Napoleon

    Science.gov (United States)

    2004-01-01

    Sir William Congreve developed a rocket with a range of about 9,000 feet. The incendiary rocket used black powder, an iron case, and a 16-foot guide stick. In 1806, British used Congreve rockets to attack Napoleon's headquarters in France. In 1807, Congreve directed a rocket attack against Copenhagen.

  20. Playing Attack and Defense with Trusted Storage

    DEFF Research Database (Denmark)

    Gonzalez, Javier; Bonnet, Philippe; Bouganim, Luc

    2014-01-01

    provide trusted storage? This is the question we tackle in this demonstration. We describe how secure devices, equipped with a trusted execution environment, differ from general purpose devices. We illustrate with our demonstration scenario, that it is much more difficult to attack a storage service...... running on a secure device, than to attack the same service running on a general purpose device....

  1. Evaluation of Crosstalk Attacks in Access Networks

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Grobe, Klaus

    2016-01-01

    WDM-PON systems regained interest as low-cost solution for metro and access networks. We present a comparative analysis of resilience of wavelength-selective and wavelength-routed architectures against crosstalk attackers. We compare the vulnerability of these architectures against attacks...

  2. Micromechanics of high temperature hydrogen attack

    NARCIS (Netherlands)

    Schlögl, Sabine M.; Giessen, Erik van der

    1999-01-01

    Hydrogen attack is a material degradation process that occurs at elevated temperatures in hydrogen-rich environments, such as found in petro-chemical installations. Weldments in components such as reactor vessels are particularly susceptible to hydrogen attack. This paper discusses a multi-scale

  3. Drammer : Deterministic Rowhammer attacks on mobile platforms

    NARCIS (Netherlands)

    Van Der Veen, Victor; Fratantonio, Yanick; Lindorfer, Martina; Gruss, Daniel; Maurice, Clémentine; Vigna, Giovanni; Bos, Herbert; Razavi, Kaveh; Giuffrida, Cristiano

    2016-01-01

    Recent work shows that the Rowhammer hardware bug can be used to craft powerful attacks and completely subvert a system. However, existing efforts either describe probabilistic (and thus unreliable) attacks or rely on special (and often unavailable) memory management features to place victim objects

  4. Rotational Rebound Attacks on Reduced Skein

    DEFF Research Database (Denmark)

    Khovratovich, Dmitry; Nikolic, Ivica; Rechberger, Christian

    2010-01-01

    In this paper we combine a recent rotational cryptanalysis with the rebound attack, which results in the best cryptanalysis of Skein, a candidate for the SHA-3 competition. The rebound attack approach was so far only applied to AES-like constructions. For the first time, we show that this approach...

  5. Revisiting attacker model for smart vehicles

    NARCIS (Netherlands)

    Petit, Jonathan; Feiri, Michael; Kargl, Frank

    Because of the potential impact on user's life in cooperative automated safety applications, the security of Vehicle-to-X communication (V2X) is mandatory. However, the current attacker model used in literature is often too network-oriented, and it is unclear what realistic attacks could be. In this

  6. Synthesis and supramolecular assembly of biomimetic polymers

    Science.gov (United States)

    Marciel, Amanda Brittany

    A grand challenge in materials chemistry is the synthesis of macromolecules and polymers with precise shapes and architectures. Polymer microstructure and architecture strongly affect the resulting functionality of advanced materials, yet understanding the static and dynamic properties of these complex macromolecules in bulk has been difficult due to their inherit polydispersity. Single molecule studies have provided a wealth of information on linear flexible and semi-flexible polymers in dilute solutions. However, few investigations have focused on industrially relevant complex topologies (e.g., star, comb, hyperbranched polymers) in industrially relevant solution conditions (e.g., semi-dilute, concentrated). Therefore, from this perspective there is a strong need to synthesize precision complex architectures for bulk studies as well as complex architectures compatible with current single molecule techniques to study static and dynamic polymer properties. In this way, we developed a hybrid synthetic strategy to produce branched polymer architectures based on chemically modified DNA. Overall, this approach enables control of backbone length and flexibility, as well as branch grafting density and chemical identity. We utilized a two-step scheme based on enzymatic incorporation of non-natural nucleotides containing bioorthogonal dibenzocyclooctyne (DBCO) functional groups along the main polymer backbone, followed by copper-free "click" chemistry to graft synthetic polymer branches or oligonucleotide branches to the DNA backbone, thereby allowing for the synthesis of a variety of polymer architectures, including three-arm stars, H-polymers, graft block copolymers, and comb polymers for materials assembly and single molecule studies. Bulk materials properties are also affected by industrial processing conditions that alter polymer morphology. Therefore, in an alternative strategy we developed a microfluidic-based approach to assemble highly aligned synthetic

  7. Predatory behaviour in synthetic protocell communities

    Science.gov (United States)

    Qiao, Yan; Li, Mei; Booth, Richard; Mann, Stephen

    2017-02-01

    Recent progress in the chemical construction of colloidal objects comprising integrated biomimetic functions is paving the way towards rudimentary forms of artificial cell-like entities (protocells). Although several new types of protocells are currently available, the design of synthetic protocell communities and investigation of their collective behaviour has received little attention. Here we demonstrate an artificial form of predatory behaviour in a community of protease-containing coacervate microdroplets and protein-polymer microcapsules (proteinosomes) that interact via electrostatic binding. The coacervate microdroplets act as killer protocells for the obliteration of the target proteinosome population by protease-induced lysis of the protein-polymer membrane. As a consequence, the proteinosome payload (dextran, single-stranded DNA, platinum nanoparticles) is trafficked into the attached coacervate microdroplets, which are then released as functionally modified killer protocells capable of rekilling. Our results highlight opportunities for the development of interacting artificial protocell communities, and provide a strategy for inducing collective behaviour in soft matter microcompartmentalized systems and synthetic protocell consortia.

  8. Synthetic Metabolic Pathways

    DEFF Research Database (Denmark)

    This volume outlines key steps associated with the design, building, and testing of synthetic metabolic pathways for optimal cell factory performance and robustness, and illustrates how data-driven learning from these steps can be used for rational cost-effective engineering of cell factories...... topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Synthetic Metabolic Pathways: Methods and Protocols aims to ensure successful results in the further study...

  9. Synthetic guide star generation

    Science.gov (United States)

    Payne, Stephen A [Castro Valley, CA; Page, Ralph H [Castro Valley, CA; Ebbers, Christopher A [Livermore, CA; Beach, Raymond J [Livermore, CA

    2008-06-10

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  10. Automatic Classification of Attacks on IP Telephony

    Directory of Open Access Journals (Sweden)

    Jakub Safarik

    2013-01-01

    Full Text Available This article proposes an algorithm for automatic analysis of attack data in IP telephony network with a neural network. Data for the analysis is gathered from variable monitoring application running in the network. These monitoring systems are a typical part of nowadays network. Information from them is usually used after attack. It is possible to use an automatic classification of IP telephony attacks for nearly real-time classification and counter attack or mitigation of potential attacks. The classification use proposed neural network, and the article covers design of a neural network and its practical implementation. It contains also methods for neural network learning and data gathering functions from honeypot application.

  11. Use of Attack Graphs in Security Systems

    Directory of Open Access Journals (Sweden)

    Vivek Shandilya

    2014-01-01

    Full Text Available Attack graphs have been used to model the vulnerabilities of the systems and their potential exploits. The successful exploits leading to the partial/total failure of the systems are subject of keen security interest. Considerable effort has been expended in exhaustive modeling, analyses, detection, and mitigation of attacks. One prominent methodology involves constructing attack graphs of the pertinent system for analysis and response strategies. This not only gives the simplified representation of the system, but also allows prioritizing the security properties whose violations are of greater concern, for both detection and repair. We present a survey and critical study of state-of-the-art technologies in attack graph generation and use in security system. Based on our research, we identify the potential, challenges, and direction of the current research in using attack graphs.

  12. Protecting Cryptographic Memory against Tampering Attack

    DEFF Research Database (Denmark)

    Mukherjee, Pratyay

    . In practice such attacks can be executed easily, e.g. by heating the device, as substantiated by numerous works in the past decade. Tampering attacks are a class of such physical attacks where the attacker can change the memory/computation, gains additional (non-black-box) knowledge by interacting...... with the faulty device and then tries to break the security. Prior works show that generically approaching such problem is notoriously difficult. So, in this dissertation we attempt to solve an easier question, known as memory-tampering, where the attacker is allowed tamper only with the memory of the device...... but not the computation. Such weaker model can still be practically useful and moreover, may provide nice building-blocks to tackle full-fledged tampering in future. In this dissertation we study different models of memory-tampering and provide a number of solutions with different flavors. Mainly we took two different...

  13. Two Improved Multiple-Differential Collision Attacks

    Directory of Open Access Journals (Sweden)

    An Wang

    2014-01-01

    Full Text Available In CHES 2008, Bogdanov proposed multiple-differential collision attacks which could be applied to the power analysis attacks on practical cryptographic systems. However, due to the effect of countermeasures on FPGA, there are some difficulties during the collision detection, such as local high noise and the lack of sampling points. In this paper, keypoints voting test is proposed for solving these problems, which can increase the success ratio from 35% to 95% on the example of one implementation. Furthermore, we improve the ternary voting test of Bogdanov, which can improve the experiment efficiency markedly. Our experiments show that the number of power traces required in our attack is only a quarter of the requirement of traditional attack. Finally, some alternative countermeasures against our attacks are discussed.

  14. Antimocrobial Polymer

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, William F. (Utica, OH); Huang, Zhi-Heng (Walnut Creek, CA); Wright, Stacy C. (Columbus, GA)

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  15. Polymer electronics

    CERN Document Server

    Geoghegan, Mark

    2013-01-01

    Polymer electronics is the science behind many important new developments in technology, such as the flexible electronic display (e-ink) and many new developments in transistor technology. Solar cells, light-emitting diodes, and transistors are all areas where plastic electronics is likely to, or is already having, a serious impact on our daily lives. With polymer transistors and light-emitting diodes now being commercialised, there is a clear need for a pedagogic text thatdiscusses the subject in a clear and concise fashion suitable for senior undergraduate and graduate students. The content

  16. Electroassembly of smart polymer structures (role of polyelectrolytes)

    Science.gov (United States)

    Wallace, Gordon G.; Adeloju, Samuel B.; Shaw, Shannon J.

    1997-02-01

    Polymers are ubiquitous in nature, owing to their use as both structural and active components in dynamic, living systems. From a synthetic point of view man has utilized the excellent structural properties of polymers (light weight/high strength) for some decades now. However, the integration of active functional polymers into engineered systems and structures is a more recent endeavour with numerous challenges still to be overcome. Conducting electroactive polymers such as polypyrroles, polythiophenes and polyanilines are a fascinating group of functional polymers. They are electronic conductors and in addition they response to chemical or electrical stimuli in a number of ways. They are truly electrofunctional polymers. This unique combination of properties has led to the use of conducting polymers for electronic components, chemical sensors and biosensors, membranes for solution or gas separations, electromechanical actuators, electro-optical devices, biomaterials capable of controlled release of drugs or stimulation of biological processes, and for corrosion protection.

  17. Combining living anionic polymerization with branching reactions in an iterative fashion to design branched polymers.

    Science.gov (United States)

    Higashihara, Tomoya; Sugiyama, Kenji; Yoo, Hee-Soo; Hayashi, Mayumi; Hirao, Akira

    2010-06-16

    This paper reviews the precise synthesis of many-armed and multi-compositional star-branched polymers, exact graft (co)polymers, and structurally well-defined dendrimer-like star-branched polymers, which are synthetically difficult, by a commonly-featured iterative methodology combining living anionic polymerization with branched reactions to design branched polymers. The methodology basically involves only two synthetic steps; (a) preparation of a polymeric building block corresponding to each branched polymer and (b) connection of the resulting building unit to another unit. The synthetic steps were repeated in a stepwise fashion several times to successively synthesize a series of well-defined target branched polymers. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Synthetic growth reference charts

    NARCIS (Netherlands)

    Hermanussen, Michael; Stec, Karol; Aßmann, Christian; Meigen, Christof; Van Buuren, Stef|info:eu-repo/dai/nl/074806777

    2016-01-01

    Objectives: To reanalyze the between-population variance in height, weight, and body mass index (BMI), and to provide a globally applicable technique for generating synthetic growth reference charts. Methods: Using a baseline set of 196 female and 197 male growth studies published since 1831, common

  19. Synthetic Plant Defense Elicitors

    Directory of Open Access Journals (Sweden)

    Yasemin eBektas

    2015-01-01

    Full Text Available To defend themselves against invading pathogens plants utilize a complex regulatory network that coordinates extensive transcriptional and metabolic reprogramming. Although many of the key players of this immunity-associated network are known, the details of its topology and dynamics are still poorly understood. As an alternative to forward and reverse genetic studies, chemical genetics-related approaches based on bioactive small molecules have gained substantial popularity in the analysis of biological pathways and networks. Use of such molecular probes can allow researchers to access biological space that was previously inaccessible to genetic analyses due to gene redundancy or lethality of mutations. Synthetic elicitors are small drug like molecules that induce plant defense responses, but are distinct from known natural elicitors of plant immunity. While the discovery of the some synthetic elicitors had already been reported in the 1970s, recent breakthroughs in combinatorial chemical synthesis now allow for inexpensive high-throughput screens for bioactive plant defense-inducing compounds. Along with powerful reverse genetics tools and resources available for model plants and crop systems, comprehensive collections of new synthetic elicitors will likely allow plant scientists to study the intricacies of plant defense signaling pathways and networks in an unparalleled fashion. As synthetic elicitors can protect crops from diseases, without the need to be directly toxic for pathogenic organisms, they may also serve as promising alternatives to conventional biocidal pesticides, which often are harmful for the environment, farmers and consumers. Here we are discussing various types of synthetic elicitors that have been used for studies on the plant immune system, their modes-of-action as well as their application in crop protection.

  20. Polymer physics

    CERN Document Server

    Gedde, Ulf W

    1999-01-01

    This book is the result of my teaching efforts during the last ten years at the Royal Institute of Technology. The purpose is to present the subject of polymer physics for undergraduate and graduate students, to focus the fundamental aspects of the subject and to show the link between experiments and theory. The intention is not to present a compilation of the currently available literature on the subject. Very few reference citations have thus been made. Each chapter has essentially the same structure: starling with an introduction, continuing with the actual subject, summarizing the chapter in 30D-500 words, and finally presenting problems and a list of relevant references for the reader. The solutions to the problems presented in Chapters 1-12 are given in Chapter 13. The theme of the book is essentially polymer science, with the exclusion of that part dealing directly with chemical reactions. The fundamentals in polymer science, including some basic polymer chemistry, are presented as an introduction in t...

  1. Conducting Polymers

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Conducting Polymers - From a Laboratory Curiosity to the Market Place. S Ramakrishnan. Volume 16 Issue 12 December 2011 pp 1254-1265. Fulltext. Click here to view fulltext PDF. Permanent link:

  2. Polymer Microneedles

    NARCIS (Netherlands)

    Yeshurun, Yehoshua; Hefetz, Meir; Berenschot, Johan W.; de Boer, Meint J.; Altpeter, Dominique; Boom, Garrit; Boom, G.

    2003-01-01

    A method for producing microneedles. The method including disposing a first layer of a radiation sensitive polymer on to a working surface and selectively irradiating the first layer such that the first layer has at least one irradiated region and at least one non-irradiated region. The method also

  3. Protecting complex infrastructures against multiple strategic attackers

    Science.gov (United States)

    Hausken, Kjell

    2011-01-01

    Infrastructures are analysed subject to defence by a strategic defender and attack by multiple strategic attackers. A framework is developed where each agent determines how much to invest in defending versus attacking each of multiple targets. A target can have economic, human and symbolic values, which generally vary across agents. Investment expenditure functions for each agent can be linear in the investment effort, concave, convex, logistic, can increase incrementally, or can be subject to budget constraints. Contest success functions (e.g., ratio and difference forms) determine the probability of a successful attack on each target, dependent on the relative investments of the defender and attackers on each target, and on characteristics of the contest. Targets can be in parallel, in series, interlinked, interdependent or independent. The defender minimises the expected damage plus the defence expenditures. Each attacker maximises the expected damage minus the attack expenditures. The number of free choice variables equals the number of agents times the number of targets, or lower if there are budget constraints. Each agent is interested in how his investments vary across the targets, and the impact on his utilities. Alternative optimisation programmes are discussed, together with repeated games, dynamic games and incomplete information. An example is provided for illustration.

  4. Classification of cyber attacks in South Africa

    CSIR Research Space (South Africa)

    Van Heerden, R

    2016-05-01

    Full Text Available various ATM's throughout South Africa. Two criminals, Motsoane and Masoleng, were arrested in February 2012 and both sentenced to 15 years in jail [36, 37]. 3.10 2013: IOL DDoS Anonymous Africa claimed responsibility for launching a Distributed Denial... of Service (DDoS) attack on the Independent Newspaper web site iol.co.za. The attack was in response to claims that the IOL group supports Zimbabwean president Robert Mugabe. The following taunt was sent to boast about the attack: “IOL bad boys bad boys...

  5. A review on introduction and applications of starch and its biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Shanta Pokhrel

    2015-12-01

    Full Text Available Biodegradable polymers play a very important role in plastic engineering by replacing non biodegradable, non renewable petrol based polymers. Starch is a renewable, biodegradable, low cost natural polymer with high availability. Natural polymers can be blended with synthetic polymers to improve their properties significantly. This article reviews advance in starch and starch based blends and presents their numerous potential applications. Therefore, this review helps to understand the importance and characteristics of starch and its biodegradable polymers (blends by its various aspects such as structural properties and wide applications.International Journal of Environment Vol.4(4 2015: 114-125

  6. Warning Signs of Heart Attack, Stroke and Cardiac Arrest

    Science.gov (United States)

    ... Heart Attack WARNING SIGNS OF HEART ATTACK, STROKE & CARDIAC ARREST HEART ATTACK WARNING SIGNS CHEST DISCOMFORT Most heart ... to the hospital immediately. Learn more about stroke CARDIAC ARREST WARNING SIGNS SUDDEN LOSS OF RESPONSIVENESS No response ...

  7. A review of semi-synthetic biopolymer complexes: modified polysaccharide nano-carriers for enhancement of oral drug bioavailability.

    Science.gov (United States)

    Sithole, Mduduzi N; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Pillay, Viness

    2017-03-01

    Semi-synthetic biopolymer complexes (SSBCs) have potential as nano-carriers for oral drug delivery due to their exceptional properties obtained by merging the properties of synthetic (e.g. good thermal and mechanical properties) with natural polymers (e.g. biocompatibility); thus, forming a new class of biopolymer materials incorporating the best of both worlds. Despite development in drug delivery systems, oral administration of therapeutic agent is still preferred. Several nano-polymeric systems has been prepared and characterized based on both synthetic polymers and natural polymers, each with its limitations and advantages. Among natural polymers, alginate, chitosan, and hyaluronic acid (HA) have been studied broadly for the fabrication of nanoparticles systems. This review discusses a newly investigated class of polymer called SSBCs as oral drug nano-carriers. It also discusses certain significant structural and functional attributes or effects which are essential to be taken into consideration when an oral drug delivery system is developed. The review is aimed at describing complexation of few natural polymers (e.g. polysaccharides) with selected synthetic polymers or synthetic chemicals to indicate some of the factors that influence preparation, solubility, formation, and stability of these SSBCs.

  8. Detecting Pulsing Denial-of-Service Attacks with Nondeterministic Attack Intervals

    Directory of Open Access Journals (Sweden)

    Xiapu Luo

    2009-01-01

    Full Text Available This paper addresses the important problem of detecting pulsing denial of service (PDoS attacks which send a sequence of attack pulses to reduce TCP throughput. Unlike previous works which focused on a restricted form of attacks, we consider a very broad class of attacks. In particular, our attack model admits any attack interval between two adjacent pulses, whether deterministic or not. It also includes the traditional flooding-based attacks as a limiting case (i.e., zero attack interval. Our main contribution is Vanguard, a new anomaly-based detection scheme for this class of PDoS attacks. The Vanguard detection is based on three traffic anomalies induced by the attacks, and it detects them using a CUSUM algorithm. We have prototyped Vanguard and evaluated it on a testbed. The experiment results show that Vanguard is more effective than the previous methods that are based on other traffic anomalies (after a transformation using wavelet transform, Fourier transform, and autocorrelation and detection algorithms (e.g., dynamic time warping.

  9. The structural diversity of artificial genetic polymers.

    Science.gov (United States)

    Anosova, Irina; Kowal, Ewa A; Dunn, Matthew R; Chaput, John C; Van Horn, Wade D; Egli, Martin

    2016-02-18

    Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA that can store genetic information and evolve in response to external stimuli. Practitioners of synthetic genetics postulate that XNA could be used to safeguard synthetic biology organisms by storing genetic information in orthogonal chromosomes. XNA polymers are also under active investigation as a source of nuclease resistant affinity reagents (aptamers) and catalysts (xenozymes) with practical applications in disease diagnosis and treatment. In this review, we provide a structural perspective on known antiparallel duplex structures in which at least one strand of the Watson-Crick duplex is composed entirely of XNA. Currently, only a handful of XNA structures have been archived in the Protein Data Bank as compared to the more than 100 000 structures that are now available. Given the growing interest in xenobiology projects, we chose to compare the structural features of XNA polymers and discuss their potential to access new regions of nucleic acid fold space. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  10. Outdoor Air Pollution, Heart Attack and Stroke

    Science.gov (United States)

    Elevated outdoor ambient air particle pollution triggers heart attacks, strokes, and abnormal heart rhythms and worsens heart failure in individuals at high risk due to underlying medical conditions. Emergency Medical Services in communities are the first responders to these eme...

  11. The role of sleep in migraine attacks

    Directory of Open Access Journals (Sweden)

    Elaine Inamorato

    1993-11-01

    Full Text Available Migraine attacks may be precipitated by sleep deprivation or excessive sleep and sleep is also associated with relief of migraine attacks. In view of this variable relationship we studied the records of 159 consecutive outpatients of our Headache Unit. In 121 records there was reference to sleep involvement, in 55% by a single form and in 45% by more than one form. When only one form was related, relief was most common (70%. 30% of that group of patients had the migraine attack precipitated by sleep, 24% by deprivation and 6% by sleep excess. When the effects of sleep were multiple, these effects were as expected logically in 65%: «in accordance» group (e.g attack precipitated by sleep deprivation and relieved by sleep onset. In a second group, («conflicting» where the involvement was not logical, there were three different combinations of sleep involvement, possibly due to more than one pathophysiological mechanism.

  12. How Is a Heart Attack Treated?

    Science.gov (United States)

    ... heart attack at age 36, it stopped her "dead in her tracks." Jennifer reminds us how heart disease takes too many of our moms, sisters, and friends from us every day. The more we share our stories, the faster ...

  13. How Is a Heart Attack Diagnosed?

    Science.gov (United States)

    ... heart attack at age 36, it stopped her "dead in her tracks." Jennifer reminds us how heart disease takes too many of our moms, sisters, and friends from us every day. The more we share our stories, the faster ...

  14. Transient ischemic attack: definition and natural history.

    Science.gov (United States)

    Caplan, Louis R

    2006-07-01

    The standard definition of a transient ischemic attack--"a cerebral dysfunction of an ischemic nature lasting no longer than 24 hours with a tendency to recur"--was arrived at arbitrarily and is no longer tenable. Experience shows that attacks are much briefer, usually less than an hour, and many are associated with brain infarction. A newer definition, more consonant with the data, is preferred--"transient ischemic attack is a brief episode of neurological dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than an hour, and without evidence of acute infarction." Patients with transient ischemic attacks require urgent evaluation that includes brain and vascular imaging, blood tests, and often cardiac investigations. Treatment will depend on the nature of the causative cervico-cranial vascular, cardiac, and hematologic abnormalities found on investigation.

  15. Diabetes - preventing heart attack and stroke

    Science.gov (United States)

    Diabetes complications - heart; Coronary artery disease - diabetes; CAD - diabetes; Cerebrovascular disease - diabetes ... People with diabetes have a higher chance of having heart attacks and strokes. Smoking and having high blood pressure and high ...

  16. Women's Heart Disease: Heart Attack Symptoms

    Science.gov (United States)

    ... this page please turn JavaScript on. Feature: Women's Heart Disease Heart Attack Symptoms Past Issues / Winter 2014 Table ... NHLBI has uncovered some of the causes of heart diseases and conditions, as well as ways to prevent ...

  17. Marine Attack on Towed Hydrophone Arrays

    National Research Council Canada - National Science Library

    Kalmijn, Ad

    2002-01-01

    The original objective of the SIO Marine Attack project was to identify the electric and magnetic fields causing sharks to inflict serious damage upon the towed hydrophone arrays of US Navy submarines...

  18. Using agility to combat cyber attacks.

    Science.gov (United States)

    Anderson, Kerry

    2017-06-01

    Some incident response practitioners feel that they have been locked in a battle with cyber criminals since the popular adoption of the internet. Initially, organisations made great inroads in preventing and containing cyber attacks. In the last few years, however, cyber criminals have become adept at eluding defence security technologies and rapidly modifying their exploit strategies for financial or political gains. Similar to changes in military combat tactics, cyber criminals utilise distributed attack cells, real-time communications, and rapidly mutating exploits to minimise the potential for detection. Cyber criminals have changed their attack paradigm. This paper describes a new incident response paradigm aimed at combating the new model of cyber attacks with an emphasis on agility to increase the organisation's ability to respond rapidly to these new challenges.

  19. Being active after your heart attack

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000093.htm Being active after your heart attack To use the sharing ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  20. Synthetic Space Vector Modulation

    Science.gov (United States)

    2013-06-01

    controller. The VSI controller has traditionally been operated by hardwired pulse-width modulation (PWM) or the use of a programmable microprocessor ...frequency. The primary difference between SVM and synthetic SVM is the implementation strategy of software versus inexpensive hardware, respectively. A...resistors and capacitors. There are no microcontrollers or FPGAs necessary to produce Alt-Rev SVM. F. DUAL OUTPUT VARIABLE FREQUENCY OSCILLATOR After

  1. Attack by Pyemotes johnmoseri (Acari: Pyemotidae)

    Science.gov (United States)

    Tulin Askit; Ibrahim Cakmak; John Moser

    2007-01-01

    The Aegean Region of Turkey is one of the largest dried fig producers in the world. A Turkish cultivar sarilop (Ficus carica cv. Calimyrna L.) possesses good qualities for drying process, and has been grown extensively for many years in Turkey. Hypoborus ficus is the most common xylophagous insect attacking fig trees in Aydin (Aks¸it et al. 2003). This pest attacks...

  2. Panic attack history and smoking topography.

    Science.gov (United States)

    Farris, Samantha G; Brown, Lily A; Goodwin, Renee D; Zvolensky, Michael J

    2017-02-01

    Little is known about panic attacks and puffing topography, a behavioral index of the value of smoking reinforcement. This study examined smoking style during the course of smoking of a single cigarette among adult daily smokers with and without a history of panic attacks. Participants (n=124, Mage=43.9, SD=9.7; 44.4% female) were non-treatment seeking daily smokers. Lifetime panic attack history was assessed via diagnostic assessment; 28.2% (n=35) of the sample had a panic attack history. Participants smoked one cigarette during an ad libitum smoking trial. Puff volume, duration, and inter-puff interval were measured using the Clinical Research Support System (CReSS) pocket device. Regression analyses revealed that panic attack status was not associated with significant differences in average puff volume, duration, or inter-puff interval. Multi-level modeling was used to examine puffing trajectories. Puff-level data revealed that there was a significant quadratic time x panic effect for puff volume and duration. Those with a panic attack history demonstrated relatively sustained levels of both puff volume and duration over time, whereas those without a history of panic attacks demonstrated an increase followed by a decrease in volume and duration over time. These effects were not accounted for by the presence of general psychopathology. Smokers with a panic attack history demonstrate more persistent efforts to self-regulate the delivery of nicotine, and thus may be at risk for continued smoking and dependence. Tailored treatment may be needed to address unique vulnerabilities among this group. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Panic Attack History and Smoking Topography

    Science.gov (United States)

    Farris, Samantha G.; Brown, Lily A.; Goodwin, Renee D.; Zvolensky, Michael J.

    2016-01-01

    Background Little is known about panic attacks and puffing topography, a behavioral index of the value of smoking reinforcement. This study examined smoking style during the course of smoking of a single cigarette among adult daily smokers with and without a history of panic attacks. Method Participants (n = 124, Mage = 43.9, SD = 9.7; 44.4% female) were non-treatment seeking daily smokers. Lifetime panic attack history was assessed via diagnostic assessment; 28.2% (n = 35) of the sample had a panic attack history. Participants smoked one cigarette during an ad libitum smoking trial. Puff volume, duration, and inter-puff interval were measured using the Clinical Research Support System (CReSS) pocket device. Results Regression analyses revealed that panic attack status was not associated with significant differences in average puff volume, duration, or inter-puff interval. Multi-level modeling was used to examine puffing trajectories. Puff-level data revealed that there was a significant quadratic time x panic effect for puff volume and duration. Those with a panic attack history demonstrated relatively sustained levels of both puff volume and duration over time, whereas those without a history of panic attacks demonstrated an increase followed by a decrease in volume and duration over time. These effects were not accounted for by the presence of general psychopathology. Discussion Smokers with a panic attack history demonstrate more persistent efforts to self-regulate the delivery of nicotine, and thus may be at risk for continued smoking and dependence. Tailored treatment may be needed to address unique vulnerabilities among this group. PMID:28033542

  4. Cyber Security Audit and Attack Detection Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Dale

    2012-05-31

    This goal of this project was to develop cyber security audit and attack detection tools for industrial control systems (ICS). Digital Bond developed and released a tool named Bandolier that audits ICS components commonly used in the energy sector against an optimal security configuration. The Portaledge Project developed a capability for the PI Historian, the most widely used Historian in the energy sector, to aggregate security events and detect cyber attacks.

  5. Synthetic lubricants and high-performance functional fluids

    CERN Document Server

    Rudnick, Leslie R

    1999-01-01

    Offers state-of-the-art information on all the major synthetic fluids, describing established products as well as highly promising experimental fluids with commercial potential. This second edition contains chapters on polyinternalolefins, polymer esters, refrigeration lubes, polyphenyl ethers, highly refined mineral oils, automotive gear oils and industrial gear oils. The book also assesses automotive, industrial, aerospace, environmental, and commercial trends in Europe, Asia, South America, and the US.

  6. Diversity screening for novel enzymes degrading synthetic polymers

    DEFF Research Database (Denmark)

    Lezyk, Mateusz Jakub

    : waste management, production of biofuels and valueadded biochemicals. Secondly, the goal was to identify new ways in which relevant enzymatic activities may be identified. Finally, the aim was to contribute to the known diversity of biocatalysts with potential to: oxidize a number of low...... and 0.9 ± 0.01 mM of 3-fucosyllactose were achieved. In conclusion, results included in this work further substantiate that the functional mining of a metagenome can lead to the successful discovery of diverse biocatalysts. This work paves the way for efficient identification of novel enzymatic...

  7. Synthetic Polymers as Drug-Delivery Vehicles in Medicine

    OpenAIRE

    Neuse, Eberhard W.

    2008-01-01

    Cancerous diseases present a formidable health problem worldwide. While the chemotherapy of cancer, in conjunction with other treatment modalities, has reached a significant level of maturity, efficacious use of such agents is still restricted by numerous pharmacological deficiencies, such as poor water solubility, short serum circulation lifetimes, and low bioavailability resulting from lack of affinity to cancer tissue and inadequate mechanisms of cell entry. More critically still, most dru...

  8. COMPOSITES BASED ON SYNTHETIC POLYMERS AND WOOD WASTE

    Directory of Open Access Journals (Sweden)

    Lucia DUMITRESCU

    2015-12-01

    Full Text Available The paper presents the results of the research dedicated to synthesis and characterization of some new, ecological composite materials based on an acrylic copolymer, lignin derivative iron and chromium lignosulfonate and Salix wood sawdust. The FT-IR analysis put into evidence the complex interactions, by esterification and etherification reactions, between the organic functional hydroxyl groups of lignosulfonate and Salix sawdust (the fillers with the organic functional groups (carboxyl, ester from the structure of acrylic copolymer (the matrix and explain the improved properties of the new composites. The proposed new composites are in agreement with the research in the field of recycling lignocellulosic waste to obtain new ecological, environmental friendly materials.

  9. Combined Heuristic Attack Strategy on Complex Networks

    Directory of Open Access Journals (Sweden)

    Marek Šimon

    2017-01-01

    Full Text Available Usually, the existence of a complex network is considered an advantage feature and efforts are made to increase its robustness against an attack. However, there exist also harmful and/or malicious networks, from social ones like spreading hoax, corruption, phishing, extremist ideology, and terrorist support up to computer networks spreading computer viruses or DDoS attack software or even biological networks of carriers or transport centers spreading disease among the population. New attack strategy can be therefore used against malicious networks, as well as in a worst-case scenario test for robustness of a useful network. A common measure of robustness of networks is their disintegration level after removal of a fraction of nodes. This robustness can be calculated as a ratio of the number of nodes of the greatest remaining network component against the number of nodes in the original network. Our paper presents a combination of heuristics optimized for an attack on a complex network to achieve its greatest disintegration. Nodes are deleted sequentially based on a heuristic criterion. Efficiency of classical attack approaches is compared to the proposed approach on Barabási-Albert, scale-free with tunable power-law exponent, and Erdős-Rényi models of complex networks and on real-world networks. Our attack strategy results in a faster disintegration, which is counterbalanced by its slightly increased computational demands.

  10. Phthalocyanine polymers

    Science.gov (United States)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

  11. Polymer blends

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Naik, Sanjeev

    2017-08-22

    The present invention provides, among other things, extruded blends of aliphatic polycarbonates and polyolefins. In one aspect, provided blends comprise aliphatic polycarbonates such as poly(propylene carbonate) and a lesser amount of a crystalline or semicrystalline polymer. In certain embodiments, provided blends are characterized in that they exhibit unexpected improvements in their elongation properties. In another aspect, the invention provides methods of making such materials and applications of the materials in applications such as the manufacture of consumer packaging materials.

  12. An oracle-based attack on CAPTCHAs protected against oracle attacks

    OpenAIRE

    Hernández-Castro, Carlos Javier; R-Moreno, María D.; David F. Barrero; Li, Shujun

    2017-01-01

    CAPTCHAs/HIPs are security mechanisms that try to prevent automatic abuse of services. They are susceptible to learning attacks in which attackers can use them as oracles. Kwon and Cha presented recently a novel algorithm that intends to avoid such learning attacks and "detect all bots". They add uncertainties to the grading of challenges, and also use trap images designed to detect bots. The authors suggest that a major IT corporation is studying their proposal for mainstream implementation....

  13. Exploiting Hardware Vulnerabilities to Attack Embedded System Devices: a Survey of Potent Microarchitectural Attacks

    Directory of Open Access Journals (Sweden)

    Apostolos P. Fournaris

    2017-07-01

    Full Text Available Cyber-Physical system devices nowadays constitute a mixture of Information Technology (IT and Operational Technology (OT systems that are meant to operate harmonically under a security critical framework. As security IT countermeasures are gradually been installed in many embedded system nodes, thus securing them from many well-know cyber attacks there is a lurking danger that is still overlooked. Apart from the software vulnerabilities that typical malicious programs use, there are some very interesting hardware vulnerabilities that can be exploited in order to mount devastating software or hardware attacks (typically undetected by software countermeasures capable of fully compromising any embedded system device. Real-time microarchitecture attacks such as the cache side-channel attacks are such case but also the newly discovered Rowhammer fault injection attack that can be mounted even remotely to gain full access to a device DRAM (Dynamic Random Access Memory. Under the light of the above dangers that are focused on the device hardware structure, in this paper, an overview of this attack field is provided including attacks, threat directives and countermeasures. The goal of this paper is not to exhaustively overview attacks and countermeasures but rather to survey the various, possible, existing attack directions and highlight the security risks that they can pose to security critical embedded systems as well as indicate their strength on compromising the Quality of Service (QoS such systems are designed to provide.

  14. Opportunities in plant synthetic biology.

    Science.gov (United States)

    Cook, Charis; Martin, Lisa; Bastow, Ruth

    2014-05-01

    Synthetic biology is an emerging field uniting scientists from all disciplines with the aim of designing or re-designing biological processes. Initially, synthetic biology breakthroughs came from microbiology, chemistry, physics, computer science, materials science, mathematics, and engineering disciplines. A transition to multicellular systems is the next logical step for synthetic biologists and plants will provide an ideal platform for this new phase of research. This meeting report highlights some of the exciting plant synthetic biology projects, and tools and resources, presented and discussed at the 2013 GARNet workshop on plant synthetic biology.

  15. Nylon-3 polymers with selective antifungal activity.

    Science.gov (United States)

    Liu, Runhui; Chen, Xinyu; Hayouka, Zvi; Chakraborty, Saswata; Falk, Shaun P; Weisblum, Bernard; Masters, Kristyn S; Gellman, Samuel H

    2013-04-10

    Host-defense peptides inhibit bacterial growth but show little toxicity toward mammalian cells. A variety of synthetic polymers have been reported to mimic this antibacterial selectivity; however, achieving comparable selectivity for fungi is more difficult because these pathogens are eukaryotes. Here we report nylon-3 polymers based on a novel subunit that display potent antifungal activity (MIC = 3.1 μg/mL for Candida albicans ) and favorable selectivity (IC10 > 400 μg/mL for 3T3 fibroblast toxicity; HC10 > 400 μg/mL for hemolysis).

  16. Scaling Reversible Adhesion in Synthetic and Biological Systems

    Science.gov (United States)

    Bartlett, Michael; Irschick, Duncan; Crosby, Alfred

    2013-03-01

    High capacity, easy release polymer adhesives, as demonstrated by a gecko's toe, present unique opportunities for synthetic design. However, without a framework that connects biological and synthetic adhesives from basic nanoscopic features to macroscopic systems, synthetic mimics have failed to perform favorably at large length scales. Starting from an energy balance, we develop a scaling approach to understand unstable interfacial fracture over multiple length scales. The simple theory reveals that reversibly adhesive polymers do not rely upon fibrillar features but require contradicting attributes: maximum compliance normal to the substrate and minimum compliance in the loading direction. We use this counterintuitive criterion to create reversible, easy release adhesives at macroscopic sizes (100 cm2) with unprecedented force capacities on the order of 3000 N. Importantly, we achieve this without fibrillar features, supporting our predictions and emphasizing the importance of subsurface anatomy in biological adhesive systems. Our theory describes adhesive force capacity as a function of material properties and geometry and is supported by over 1000 experiments, spanning both synthetic and biological adhesives, with agreement over 14 orders of magnitude in adhesive force.

  17. Recent Advances in Glycerol Polymers: Chemistry and Biomedical Applications

    Science.gov (United States)

    Zhang, Heng

    2015-01-01

    Glycerol polymers are attracting increased attention due to the diversity of polymer compositions and architectures available. This article provides a brief chronological review on the current status of these polymers along with representative examples of their use for biomedical applications. First, we describe the underlying chemistry of glycerol, which provides access to a range of monomers for subsequent polymerizations. We then review the various synthetic methodologies to prepare glycerol-based polymers including polyethers, polycarbonates, polyesters, and so forth. Next, we describe several biomedical applications where glycerol polymers are being investigated including carriers for drug delivery, sealants or coatings for tissue repair, and agents possessing antibacterial activity. Fourth, we describe the growing market opportunity for the use of polymers in medicine. Finally we conclude and summarize the findings, as well as discuss potential opportunities for continued research efforts. PMID:25308354

  18. Recent advances in glycerol polymers: chemistry and biomedical applications.

    Science.gov (United States)

    Zhang, Heng; Grinstaff, Mark W

    2014-11-01

    Glycerol polymers are attracting increased attention due to the diversity of polymer compositions and architectures available. This article provides a brief chronological review on the current status of these polymers along with representative examples of their use for biomedical applications. First, the underlying chemistry of glycerol that provides access to a range of monomers for subsequent polymerizations is described. Then, the various synthetic methodologies to prepare glycerol-based polymers including polyethers, polycarbonates, polyesters, and so forth are reviewed. Next, several biomedical applications where glycerol polymers are being investigated including carriers for drug delivery, sealants or coatings for tissue repair, and agents possessing antibacterial activity are described. Fourth, the growing market opportunity for the use of polymers in medicine is described. Finally, the findings are concluded and summarized, as well as the potential opportunities for continued research efforts are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Multidisciplinary synthetic approach for rapid combinatorial library synthesis of triaza-fluorenes.

    Science.gov (United States)

    Hsiao, Ya-Shan; Yellol, Gorakh S; Chen, Li-Hsun; Sun, Chung-Ming

    2010-09-13

    A new multidisciplinary synthetic approach comprising polymer-support synthesis, microwave-assisted synthesis, and multicomponent condensation facilitates synthesis of triaza-fluorenes library with a set of advantages such as rapid process, simple purification, and structural diversity in one shot. Microwave-assisted multistep synthetic protocol was used to construct the benzimidazole ring on soluble polymer support using activated aryl-fluorides. The PEG anchored aryl fluoride was condensed with selective primary amines via an ipso-fluoro displacement reaction followed by reduction of nitro group. The subsequent cyclization with cyanogen bromide is used as a key step to furnish immobilized benzimidazoles. Finally multicomponent condensation of resulted polymer bound benzimidazoles with various aldehydes and 1,3-diones under microwave irradiations provides rapid access for triaza-fluorenes with high purity and excellent yields. Microwave irradiation greatly accelerates the rate of all reactions while polymer support facilitates purifications by simple precipitation technique. This strategy dramatically increases efficiency of overall multistep synthesis.

  20. Intracellular production of hydrogels and synthetic RNA granules by multivalent molecular interactions

    Science.gov (United States)

    Nakamura, Hideki; Lee, Albert A.; Afshar, Ali Sobhi; Watanabe, Shigeki; Rho, Elmer; Razavi, Shiva; Suarez, Allister; Lin, Yu-Chun; Tanigawa, Makoto; Huang, Brian; Derose, Robert; Bobb, Diana; Hong, William; Gabelli, Sandra B.; Goutsias, John; Inoue, Takanari

    2018-01-01

    Some protein components of intracellular non-membrane-bound entities, such as RNA granules, are known to form hydrogels in vitro. The physico-chemical properties and functional role of these intracellular hydrogels are difficult to study, primarily due to technical challenges in probing these materials in situ. Here, we present iPOLYMER, a strategy for a rapid induction of protein-based hydrogels inside living cells that explores the chemically inducible dimerization paradigm. Biochemical and biophysical characterizations aided by computational modelling show that the polymer network formed in the cytosol resembles a physiological hydrogel-like entity that acts as a size-dependent molecular sieve. We functionalize these polymers with RNA-binding motifs that sequester polyadenine-containing nucleotides to synthetically mimic RNA granules. These results show that iPOLYMER can be used to synthetically reconstitute the nucleation of biologically functional entities, including RNA granules in intact cells.

  1. Synthetic cannabinoids revealing adrenoleukodystrophy.

    Science.gov (United States)

    Fellner, Avi; Benninger, Felix; Djaldetti, Ruth

    2016-02-01

    We report a 41-year-old man who presented with a first generalized tonic-clonic seizure after recent consumption of a synthetic cannabinoid. MRI showed extensive bilateral, mainly frontal, white matter lesions. Blood analysis for very long chain fatty acids was compatible with adrenoleukodystrophy, and a missense mutation in the ABCD1 gene confirmed the diagnosis. We hypothesize that cannabinoid use might have contributed to metabolic decompensation with subacute worsening of the underlying condition. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. A Game Theoretic Approach to Cyber Attack Prediction

    Energy Technology Data Exchange (ETDEWEB)

    Peng Liu

    2005-11-28

    The area investigated by this project is cyber attack prediction. With a focus on correlation-based prediction, current attack prediction methodologies overlook the strategic nature of cyber attack-defense scenarios. As a result, current cyber attack prediction methodologies are very limited in predicting strategic behaviors of attackers in enforcing nontrivial cyber attacks such as DDoS attacks, and may result in low accuracy in correlation-based predictions. This project develops a game theoretic framework for cyber attack prediction, where an automatic game-theory-based attack prediction method is proposed. Being able to quantitatively predict the likelihood of (sequences of) attack actions, our attack prediction methodology can predict fine-grained strategic behaviors of attackers and may greatly improve the accuracy of correlation-based prediction. To our best knowledge, this project develops the first comprehensive framework for incentive-based modeling and inference of attack intent, objectives, and strategies; and this project develops the first method that can predict fine-grained strategic behaviors of attackers. The significance of this research and the benefit to the public can be demonstrated to certain extent by (a) the severe threat of cyber attacks to the critical infrastructures of the nation, including many infrastructures overseen by the Department of Energy, (b) the importance of cyber security to critical infrastructure protection, and (c) the importance of cyber attack prediction to achieving cyber security.

  3. Power analysis attacks revealing the secrets of smart cards

    CERN Document Server

    Mangard, Stefan; Popp, Thomas

    2008-01-01

    A comprehensive treatment of power analysis attacks and countermeasures. Based on the principle that the only way to defend against power analysis attacks is to understand them, this book explains how power analysis attacks work. It discusses simple and differential power analysis as well as advanced techniques like template attacks.

  4. Transforming Graphical System Models to Graphical Attack Models

    DEFF Research Database (Denmark)

    Ivanova, Marieta Georgieva; Probst, Christian W.; Hansen, Rene Rydhof

    2016-01-01

    approach to transforming graphical system models to graphical attack models in the form of attack trees. Based on an asset in the model, our transformations result in an attack tree that represents attacks by all possible actors in the model, after which the actor in question has obtained the asset....

  5. Fault Analysis Attacks and Its Countermeasure using Elliptic Curve Cryptography

    OpenAIRE

    M. Prabu; R. Shanmugalakshmi

    2010-01-01

    In the last decade, many researchers had published the overall analysis attacks of cryptographic devices against implementation on elliptic curve attacks. Usually such type of information is not sufficient to learn about the individual attacks. Now in this article, we indisputably concentrated on fault analysis attack and its countermeasure.

  6. Modelling Social-Technical Attacks with Timed Automata

    NARCIS (Netherlands)

    David, Nicolas; David, Alexandre; Hansen, René Rydhof; Larsen, K.G.; Legay, Axel; Olesen, Mads Chr.; Probst, Christian W.

    2015-01-01

    Attacks on a system often exploit vulnerabilities that arise from human behaviour or other human activity. Attacks of this type, so-called socio-technical attacks, cover everything from social engineering to insider attacks, and they can have a devastating impact on an unprepared organisation. In

  7. Noncombatants and liability to be attacked in wars

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2013-01-01

    attack," I mean that S has forfeited his or her right not to be attacked by armed forces. Here, "liable" is used in a normative-cum-legal sense, not descriptively as it is when one says "some colors are liable to darken in perpetual shade," and "attack" is used passively, as an equivalent of be attacked...

  8. Modeling attacking of high skills volleyball players

    Directory of Open Access Journals (Sweden)

    Vladimir Gamaliy

    2014-12-01

    Full Text Available Purpose: to determine the model indicators of technical and tactical actions in the attack highly skilled volleyball players. Material and Methods: the study used statistical data of major international competitions: Olympic Games – 2012 World Championships – 2010, World League – 2010–2014 European Championship – 2010–2014. A total of 130 analyzed games. Methods were used: analysis and generalization of scientific and methodological literature, analysis of competitive activity highly skilled volleyball players, teacher observation, modeling technical and tactical actions in attacking highly skilled volleyball players. Results: it was found that the largest volume application of technical and tactical actions in the attack belongs to the group tactics «supple movement», whose indicator is 21,3%. The smallest amount of application belongs to the group tactics «flight level» model whose indicators is 5,4%, the efficiency of 3,4%, respectively. It is found that the power service in the jump from model parameters used in 51,6% of cases, the planning targets – 21,7% and 4,4% planning to reduce. Attacks performed with the back line, on model parameters used in the amount of 20,8% efficiency –13,7%. Conclusions: we prove that the performance of technical and tactical actions in the attack can be used as model in the control system of training and competitive process highly skilled volleyball players

  9. Trace Attack against Biometric Mobile Applications

    Directory of Open Access Journals (Sweden)

    Sanaa Ghouzali

    2016-01-01

    Full Text Available With the exponential increase in the dependence on mobile devices in everyday life, there is a growing concern related to privacy and security issues in the Gulf countries; therefore, it is imperative that security threats should be analyzed in detail. Mobile devices store enormous amounts of personal and financial information, unfortunately without any security. In order to secure mobile devices against different threats, biometrics has been applied and shown to be effective. However, biometric mobile applications are also vulnerable to several types of attacks that can decrease their security. Biometric information itself is considered sensitive data; for example, fingerprints can leave traces in touched objects and facial images can be captured everywhere or accessed by the attacker if the facial image is stored in the mobile device (lost or stolen. Hence, an attacker can easily forge the identity of a legitimate user and access data on a device. In this paper, the effects of a trace attack on the sensitivity of biometric mobile applications are investigated in terms of security and user privacy. Experimental results carried out on facial and fingerprint mobile authentication applications using different databases have shown that these mobile applications are vulnerable to the proposed attack, which poses a serious threat to the overall system security and user privacy.

  10. Panic Attack during Elective Gastrointestinal Endoscopy

    Directory of Open Access Journals (Sweden)

    Charalampos Mitsonis

    2011-01-01

    Full Text Available Background. Esophagogastroduodenoscopy (EGD and colonoscopy (CS can evoke anxiety, embarrassment, and discomfort. These concerns can culminate in panic attacks, which may traumatize patients and significantly decrease their compliance to the procedure. The objective of this study was to evaluate the relationship between preendoscopic anxiety and the possibility of a panic attack during an elective gastrointestinal endoscopy (EGE. Methods. The study population comprised of 79 Greek outpatients. The examination was carried out without the use of conscious sedation. Patients' anxiety levels were assessed before the procedure using the Greek version of the Spielberger State-Trait Anxiety Inventory (STAI-Y. Results. Seventy-nine patients were enrolled: 45 EGD and 34 CS. Females had higher state and trait anxiety levels than males (48.14 ± 7.94 versus 44.17 ± 7.43, <0.05; and 43.68 ± 6.95 versus 39.86 ± 7.46, <0.05. Patients who experienced panic attack had significantly higher levels of both trait and state anxiety, compared to those who were panic-free. There was no significant relationship between panic attacks and sex or type of procedure. Conclusions. Patients who experience panic attacks during endoscopic procedures appear to have significantly higher anxiety levels before the procedure. Administering the STAI questionnaire prior to the endoscopy seems to be a useful screening method for vulnerable patients.

  11. On the anatomy of social engineering attacks : A literature-based dissection of successful attacks

    NARCIS (Netherlands)

    Bullee, Jan-Willem; Montoya, L.; Pieters, Wolter; Junger, Marianne; Hartel, Pieter H.

    2017-01-01

    The aim of this studywas to explore the extent towhich persuasion principles are used in successful social engineering attacks. Seventy-four scenarioswere extracted from 4 books on social engineering (written by social engineers) and analysed. Each scenariowas split into attack steps, containing

  12. Investigation on design and synthesis of biologically controlled polymers; Seitai seigyo kobunshi no sekkei gosei no chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-03-01

    A biologically controlled polymer synthetic process is a process to control reactions by using such biological molecules as enzymes and genes to synthesize polymers. Since the process consists of synthetic reactions controlled by such biological molecules as enzymes and genes, the process is expected to exhibit various excellent characteristics such as reaction selectivity, structural orderness, and moderateness in the reacting conditions. However, the most important characteristic is its environmental harmony. The present investigation has viewed the current status of researches and the future research problems by positioning the biologically controlled polymer synthetic process as an environmentally harmonized process. The present investigation has focused its emphasis on the following three biologically controlled synthetic processes. The first is a gene controlled protein synthetic process; the second is an enzyme controlled polymer synthetic process; and the third is a biologically controlled inorganic and organic hybrids synthetic process. Particularly, the biologically controlled polymer synthetic process is a process to synthesize polymers by utilizing biologically controlled molecules in genes. 3 refs.

  13. Cross-site scripting attacks procedure and Prevention Strategies

    Directory of Open Access Journals (Sweden)

    Wang Xijun

    2016-01-01

    Full Text Available Cross-site scripting attacks and defense has been the site of attack and defense is an important issue, this paper, the definition of cross-site scripting attacks, according to the current understanding of the chaos on the cross-site scripting, analyzes the causes and harm cross-site scripting attacks formation of attacks XXS complete process XSS attacks made a comprehensive analysis, and then for the web program includes Mobility there are cross-site scripting filter laxity given from ordinary users browse the web and web application developers two the defense cross-site scripting attacks effective strategy.

  14. Synthetic collective intelligence.

    Science.gov (United States)

    Solé, Ricard; Amor, Daniel R; Duran-Nebreda, Salva; Conde-Pueyo, Núria; Carbonell-Ballestero, Max; Montañez, Raúl

    2016-10-01

    Intelligent systems have emerged in our biosphere in different contexts and achieving different levels of complexity. The requirement of communication in a social context has been in all cases a determinant. The human brain, probably co-evolving with language, is an exceedingly successful example. Similarly, social insects complex collective decisions emerge from information exchanges between many agents. The difference is that such processing is obtained out of a limited individual cognitive power. Computational models and embodied versions using non-living systems, particularly involving robot swarms, have been used to explore the potentiality of collective intelligence. Here we suggest a novel approach to the problem grounded in the genetic engineering of unicellular systems, which can be modified in order to interact, store memories or adapt to external stimuli in collective ways. What we label as Synthetic Swarm Intelligence defines a parallel approach to the evolution of computation and swarm intelligence and allows to explore potential embodied scenarios for decision making at the microscale. Here, we consider several relevant examples of collective intelligence and their synthetic organism counterparts. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Nanotribology of charged polymer brushes

    Science.gov (United States)

    Klein, Jacob

    Polymers at surfaces, whose modern understanding may be traced back to early work by Sam Edwards1, have become a paradigm for modification of surface properties, both as steric stabilizers and as remarkable boundary lubricants2. Charged polymer brushes are of particular interest, with both technological implications and especially biological relevance where most macromolecules are charged. In the context of biolubrication, relevant in areas from dry eye syndrome to osteoarthritis, charged polymer surface phases and their complexes with other macromolecules may play a central role. The hydration lubrication paradigm, where tenaciously-held yet fluid hydration shells surrounding ions or zwitterions serve as highly-efficient friction-reducing elements, has been invoked to understand the excellent lubrication provided both by ionized3 and by zwitterionic4 brushes. In this talk we describe recent advances in our understanding of the nanotribology of such charged brush systems. We consider interactions between charged end-grafted polymers, and how one may disentangle the steric from the electrostatic surface forces5. We examine the limits of lubrication by ionized brushes, both synthetic and of biological origins, and how highly-hydrated zwitterionic chains may provide extremely effective boundary lubrication6. Finally we describe how the lubrication of articular cartilage in the major joints, a tribosystem presenting some of the greatest challenges and opportunities, may be understood in terms of a supramolecular synergy between charged surface-attached polymers and zwitterionic groups7. Work supported by European Research Council (HydrationLube), Israel Science Foundation (ISF), Petroleum Research Fund of the American Chemical Society, ISF-NSF China Joint Program.

  16. Tunable Optical Polymer Systems

    National Research Council Canada - National Science Library

    Jenekhe, S. A; Bard, Allen J; Chen, S. H; Hammond, P. T; Rothberg, L. J

    2004-01-01

    .... The synthesis and properties of new electrochromic polymers are described. Electrochromic devices incorporating conjugated polymers have been fabricated and found to be durable past 100,000 cycles...

  17. Rotational Rebound Attacks on Reduced Skein

    DEFF Research Database (Denmark)

    Khovratovich, Dmitry; Nikolić, Ivica; Rechberger, Christian

    2014-01-01

    number of rounds. We also use neutral bits and message modification methods from the practice of collision search in MD5 and SHA-1 hash functions. These methods push the rotational property through more rounds than previous analysis suggested, and eventually establish a distinguishing property......In this paper we combine two powerful methods of symmetric cryptanalysis: rotational cryptanalysis and the rebound attack. Rotational cryptanalysis was designed for the analysis of bit-oriented designs like ARX (Addition-Rotation-XOR) schemes. It has been applied to several hash functions and block...... ciphers, including the new standard SHA-3 (Keccak). The rebound attack is a start-from-the-middle approach for finding differential paths and conforming pairs in byte-oriented designs like Substitution-Permutation networks and AES. We apply our new compositional attack to the reduced version of the hash...

  18. Limb-shaking transient ischemic attack

    Directory of Open Access Journals (Sweden)

    Abhijit Das

    2013-01-01

    Full Text Available Limb shaking Transient Ischemic Attack is a rare manifestation of carotid-occlusive disease. The symptoms usually present with seizure like activity and often misdiagnosed as focal seizures. Only on careful history the important clinical clues-which may help in differentiating from seizure-are revealed: Lack of Jacksonian march or aura; precipitation by maneuvers that lead to carotid compression. We present the case of an elderly gentleman with recurrent limb shaking transient ischemic attacks that was initially diagnosed as a case of epilepsy. His symptoms responded to optimization of blood pressure. The case report highlights the importance of accurate diagnosis as the treatment of the associated carotid artery occlusion may not only abolish the attacks but also reduce the risk of future stroke.

  19. Twisted Polynomials and Forgery Attacks on GCM

    DEFF Research Database (Denmark)

    Abdelraheem, Mohamed Ahmed A. M. A.; Beelen, Peter; Bogdanov, Andrey

    2015-01-01

    nonce misuse resistance, such as POET. The algebraic structure of polynomial hashing has given rise to security concerns: At CRYPTO 2008, Handschuh and Preneel describe key recovery attacks, and at FSE 2013, Procter and Cid provide a comprehensive framework for forgery attacks. Both approaches rely...... heavily on the ability to construct forgery polynomials having disjoint sets of roots, with many roots (“weak keys”) each. Constructing such polynomials beyond naïve approaches is crucial for these attacks, but still an open problem. In this paper, we comprehensively address this issue. We propose to use...... twisted polynomials from Ore rings as forgery polynomials. We show how to construct sparse forgery polynomials with full control over the sets of roots. We also achieve complete and explicit disjoint coverage of the key space by these polynomials. We furthermore leverage this new construction...

  20. Conditional beam splitting attack on quantum key distribution

    OpenAIRE

    Calsamiglia, John; Barnett, Stephen M.; Lütkenhaus, Norbert

    2001-01-01

    We present a novel attack on quantum key distribution based on the idea of adaptive absorption [calsam01]. The conditional beam splitting attack is shown to be much more efficient than the conventional beam spitting attack, achieving a performance similar to the, powerful but currently unfeasible, photon number splitting attack. The implementation of the conditional beam splitting attack, based solely on linear optical elements, is well within reach of current technology.

  1. Discovering Collaborative Cyber Attack Patterns Using Social Network Analysis

    Science.gov (United States)

    Du, Haitao; Yang, Shanchieh Jay

    This paper investigates collaborative cyber attacks based on social network analysis. An Attack Social Graph (ASG) is defined to represent cyber attacks on the Internet. Features are extracted from ASGs to analyze collaborative patterns. We use principle component analysis to reduce the feature space, and hierarchical clustering to group attack sources that exhibit similar behavior. Experiments with real world data illustrate that our framework can effectively reduce from large dataset to clusters of attack sources exhibiting critical collaborative patterns.

  2. Viden: Attacker Identification on In-Vehicle Networks

    OpenAIRE

    Cho, Kyong-Tak; Shin, Kang

    2017-01-01

    Various defense schemes --- which determine the presence of an attack on the in-vehicle network --- have recently been proposed. However, they fail to identify which Electronic Control Unit (ECU) actually mounted the attack. Clearly, pinpointing the attacker ECU is essential for fast/efficient forensic, isolation, security patch, etc. To meet this need, we propose a novel scheme, called Viden (Voltage-based attacker identification), which can identify the attacker ECU by measuring and utilizi...

  3. Compartmentalization and Transport in Synthetic Vesicles

    Directory of Open Access Journals (Sweden)

    Christine eSchmitt

    2016-02-01

    Full Text Available Nano-scale vesicles have become a popular tool in life sciences. Besides liposomes that are generated from phospholipids of natural origin, polymersomes fabricated of synthetic block copolymers enjoy increasing popularity, as they represent more versatile membrane building blocks that can be selected based on their specific physicochemical properties, like permeability, stability or chemical reactivity.In this review, we focus on the application of simple and nested artificial vesicles in synthetic biology. First, we provide an introduction into the utilization of multi-compartmented vesosomes as compartmentalized nano-scale bioreactors. In the bottom-up development of protocells from vesicular nano-reactors, the specific exchange of pathway intermediates across compartment boundaries represents a bottleneck for future studies. To date, most compartmented bioreactors rely on unspecific exchange of substrates and products. This is either based on changes in permeability of the coblock polymer shell by physicochemical triggers or by the incorporation of unspecific porin proteins into the vesicle membrane. Since the incorporation of membrane transport proteins into simple and nested artificial vesicles offers the potential for specific exchange of substances between subcompartments, it opens new vistas in the design of protocells. Therefore we devote the main part of the review to summarize the technical advances in the use of phospholipids and block copolymers for the reconstitution of membrane proteins.

  4. From Commodity Polymers to Functional Polymers

    OpenAIRE

    Tao Xiang,; Ling-Ren Wang; Lang Ma; Zhi-Yuan Han; Rui Wang; Chong Cheng; Yi Xia; Hui Qin; Chang-Sheng Zhao

    2014-01-01

    Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outs...

  5. Survival of child after lion attack

    OpenAIRE

    Carlos F Dabdoub; Dabdoub, Carlos B.; Chavez, Mario; Molina, Felipe

    2013-01-01

    Background: Injuries to humans caused by attacks from large predators are very rare, especially in the United States, Europe, or Latin America. A few cases were reported on accidents in zoos or animal farms, being very uncommon in children. The purposes of this report include describing the case of a child who sustained an attack by a lion named ?Bang-Bang?, which resulted in injuries to the head, chest, and abdomen, as well as the subsequent neurosurgical treatment and providing a review of ...

  6. Space Synthetic Biology Project

    Science.gov (United States)

    Howard, David; Roman, Monsi; Mansell, James (Matt)

    2015-01-01

    Synthetic biology is an effort to make genetic engineering more useful by standardizing sections of genetic code. By standardizing genetic components, biological engineering will become much more similar to traditional fields of engineering, in which well-defined components and subsystems are readily available in markets. Specifications of the behavior of those components and subsystems can be used to model a system which incorporates them. Then, the behavior of the novel system can be simulated and optimized. Finally, the components and subsystems can be purchased and assembled to create the optimized system, which most often will exhibit behavior similar to that indicated by the model. The Space Synthetic Biology project began in 2012 as a multi-Center effort. The purpose of this project was to harness Synthetic Biology principals to enable NASA's missions. A central target for application was to Environmental Control & Life Support (ECLS). Engineers from NASA Marshall Space Flight Center's (MSFC's) ECLS Systems Development Branch (ES62) were brought into the project to contribute expertise in operational ECLS systems. Project lead scientists chose to pursue the development of bioelectrochemical technologies to spacecraft life support. Therefore, the ECLS element of the project became essentially an effort to develop a bioelectrochemical ECLS subsystem. Bioelectrochemical systems exploit the ability of many microorganisms to drive their metabolisms by direct or indirect utilization of electrical potential gradients. Whereas many microorganisms are capable of deriving the energy required for the processes of interest (such as carbon dioxide (CO2) fixation) from sunlight, it is believed that subsystems utilizing electrotrophs will exhibit smaller mass, volume, and power requirements than those that derive their energy from sunlight. In the first 2 years of the project, MSFC personnel conducted modeling, simulation, and conceptual design efforts to assist the

  7. Finding Hope in Synthetic Biology.

    Science.gov (United States)

    Takala, Tuija

    2017-04-01

    For some, synthetic biology represents great hope in offering possible solutions to many of the world's biggest problems, from hunger to sustainable development. Others remain fearful of the harmful uses, such as bioweapons, that synthetic biology can lend itself to, and most hold that issues of biosafety are of utmost importance. In this article, I will evaluate these points of view and conclude that although the biggest promises of synthetic biology are unlikely to become reality, and the probability of accidents is fairly substantial, synthetic biology could still be seen to benefit humanity by enhancing our ethical understanding and by offering a boost to world economy.

  8. Synthetic biology and occupational risk.

    Science.gov (United States)

    Howard, John; Murashov, Vladimir; Schulte, Paul

    2017-03-01

    Synthetic biology is an emerging interdisciplinary field of biotechnology that involves applying the principles of engineering and chemical design to biological systems. Biosafety professionals have done an excellent job in addressing research laboratory safety as synthetic biology and gene editing have emerged from the larger field of biotechnology. Despite these efforts, risks posed by synthetic biology are of increasing concern as research procedures scale up to industrial processes in the larger bioeconomy. A greater number and variety of workers will be exposed to commercial synthetic biology risks in the future, including risks to a variety of workers from the use of lentiviral vectors as gene transfer devices. There is a need to review and enhance current protection measures in the field of synthetic biology, whether in experimental laboratories where new advances are being researched, in health care settings where treatments using viral vectors as gene delivery systems are increasingly being used, or in the industrial bioeconomy. Enhanced worker protection measures should include increased injury and illness surveillance of the synthetic biology workforce; proactive risk assessment and management of synthetic biology products; research on the relative effectiveness of extrinsic and intrinsic biocontainment methods; specific safety guidance for synthetic biology industrial processes; determination of appropriate medical mitigation measures for lentiviral vector exposure incidents; and greater awareness and involvement in synthetic biology safety by the general occupational safety and health community as well as by government occupational safety and health research and regulatory agencies.

  9. Life after the synthetic cell

    DEFF Research Database (Denmark)

    Rasmussen, Steen

    2010-01-01

    Nature asked eight synthetic-biology experts about the implications for science and society of the “synthetic cell” made by the J. Craig Venter Institute (JCVI). The institute's team assembled, modified and implanted a synthesized genome into a DNA-free bacterial shell to make a self-replicating ......Nature asked eight synthetic-biology experts about the implications for science and society of the “synthetic cell” made by the J. Craig Venter Institute (JCVI). The institute's team assembled, modified and implanted a synthesized genome into a DNA-free bacterial shell to make a self...

  10. Drug delivery's quest for polymers: Where are the frontiers?

    Science.gov (United States)

    Merkle, Hans P

    2015-11-01

    Since the legendary 1964 article of Folkman and Long entitled "The use of silicone rubber as a carrier for prolonged drug therapy" the role of polymers in controlled drug delivery has come a long way. Today it is evident that polymers play a crucial if not the prime role in this field. The latest boost owes to the interest in drug delivery for the purpose of tissue engineering in regenerative medicine. The focus of this commentary is on a selection of general and personal observations that are characteristic for the current state of polymer therapeutics and carriers. It briefly highlights selected examples for the long march of synthetic polymer-drug conjugates from bench to bedside, comments on the ambivalence of selected polymers as inert excipients versus biological response modifiers, and on the yet unsolved dilemma of cationic polymers for the delivery of nucleic acid therapeutics. Further subjects are the complex design of multifunctional polymeric carriers including recent concepts towards functional supramolecular polymers, as well as observations on stimuli-sensitive polymers and the currently ongoing trend towards natural and naturally-derived biopolymers. The final topic is the discovery and early development of a novel type of biodegradable polyesters for parenteral use. Altogether, it is not the basic and applied research in polymer therapeutics and carriers, but the translational process that is the key hurdle to proceed towards an authoritative approval of new polymer therapeutics and carriers. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Transionospheric synthetic aperture imaging

    CERN Document Server

    Gilman, Mikhail; Tsynkov, Semyon

    2017-01-01

    This landmark monograph presents the most recent mathematical developments in the analysis of ionospheric distortions of SAR images and offers innovative new strategies for their mitigation. As a prerequisite to addressing these topics, the book also discusses the radar ambiguity theory as it applies to synthetic aperture imaging and the propagation of radio waves through the ionospheric plasma, including the anisotropic and turbulent cases. In addition, it covers a host of related subjects, such as the mathematical modeling of extended radar targets (as opposed to point-wise targets) and the scattering of radio waves off those targets, as well as the theoretical analysis of the start-stop approximation, which is used routinely in SAR signal processing but often without proper justification. The mathematics in this volume is clean and rigorous – no assumptions are hidden or ambiguously stated. The resulting work is truly interdisciplinary, providing both a comprehensive and thorough exposition of the field,...

  12. Variation and Synthetic Speech

    CERN Document Server

    Miller, C; Massey, N; Miller, Corey; Karaali, Orhan; Massey, Noel

    1997-01-01

    We describe the approach to linguistic variation taken by the Motorola speech synthesizer. A pan-dialectal pronunciation dictionary is described, which serves as the training data for a neural network based letter-to-sound converter. Subsequent to dictionary retrieval or letter-to-sound generation, pronunciations are submitted a neural network based postlexical module. The postlexical module has been trained on aligned dictionary pronunciations and hand-labeled narrow phonetic transcriptions. This architecture permits the learning of individual postlexical variation, and can be retrained for each speaker whose voice is being modeled for synthesis. Learning variation in this way can result in greater naturalness for the synthetic speech that is produced by the system.

  13. Evolutionary synthetic biology.

    Science.gov (United States)

    Peisajovich, Sergio G

    2012-06-15

    Signaling networks process vast amounts of environmental information to generate specific cellular responses. As cellular environments change, signaling networks adapt accordingly. Here, I will discuss how the integration of synthetic biology and directed evolution approaches is shedding light on the molecular mechanisms that guide the evolution of signaling networks. In particular, I will review studies that demonstrate how different types of mutations, from the replacement of individual amino acids to the shuffling of modular domains, lead to markedly different evolutionary trajectories and consequently to diverse network rewiring. Moreover, I will argue that intrinsic evolutionary properties of signaling proteins, such as the robustness of wild type functions, the promiscuous nature of evolutionary intermediates, and the modular decoupling between binding and catalysis, play important roles in the evolution of signaling networks. Finally, I will argue that rapid advances in our ability to synthesize DNA will radically alter how we study signaling network evolution at the genome-wide level.

  14. Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Gammelmark, Kim Løkke

    2006-01-01

    The paper describes the use of synthetic aperture (SA) imaging in medical ultrasound. SA imaging is a radical break with today's commercial systems, where the image is acquired sequentially one image line at a time. This puts a strict limit on the frame rate and the possibility of acquiring...... of SA imaging. Due to the complete data set, it is possible to have both dynamic transmit and receive focusing to improve contrast and resolution. It is also possible to improve penetration depth by employing codes during ultrasound transmission. Data sets for vector flow imaging can be acquired using...... short imaging sequences, whereby both the correct velocity magnitude and angle can be estimated. A number of examples of both phantom and in-vivo SA images will be presented measured by the experimental ultrasound scanner RASMUS to demonstrate the many benefits of SA imaging....

  15. Gas Sensors Based on Electrodeposited Polymers

    Directory of Open Access Journals (Sweden)

    Boris Lakard

    2015-07-01

    Full Text Available Electrochemically deposited polymers, also called “synthetic metals”, have emerged as potential candidates for chemical sensing due to their interesting and tunable chemical, electrical, and structural properties. In particular, most of these polymers (including polypyrrole, polyaniline, polythiophene and their derivatives can be used as the sensitive layer of conductimetric gas sensors because of their conducting properties. An important advantage of polymer-based gas sensors is their efficiency at room temperature. This characteristic is interesting since most of the commercially-available sensors, usually based on metal oxides, work at high temperatures (300–400 °C. Consequently, polymer-based gas sensors are playing a growing role in the improvement of public health and environment control because they can lead to gas sensors operating with rapid detection, high sensitivity, small size, and specificity in atmospheric conditions. In this review, the recent advances in electrodeposited polymer-based gas sensors are summarized and discussed. It is shown that the sensing characteristics of electrodeposited polymers can be improved by chemical functionalization, nanostructuration, or mixing with other functional materials to form composites or hybrid materials.

  16. New peptidomimetic polymers for antifouling surfaces.

    Science.gov (United States)

    Statz, Andrea R; Meagher, Robert J; Barron, Annelise E; Messersmith, Phillip B

    2005-06-08

    Exposure of therapeutic and diagnostic medical devices to biological fluids is often accompanied by interfacial adsorption of proteins, cells, and microorganisms. Biofouling of surfaces can lead to compromised device performance or increased cost and in some cases may be life-threatening to the patient. Although numerous antifouling polymer coatings have enjoyed short-term success in preventing protein and cell adsorption on surfaces, none have proven ideal for conferring long-term biofouling resistance. Here we describe a new biomimetic antifouling N-substituted glycine polymer (peptoid) containing a C-terminal peptide anchor derived from residues found in mussel adhesive proteins for robust attachment of the polymer onto surfaces. The methoxyethyl side chain of the peptoid portion of the polymer was chosen for its chemical resemblance to the repeat unit of the known antifouling polymer poly(ethylene glycol) (PEG), whereas the composition of the 5-mer anchoring peptide was chosen to directly mimic the DOPA- and Lys-rich sequence of a known mussel adhesive protein. Surfaces modified with this biomimetic peptide-peptoid conjugate exhibited dramatic reduction of serum protein adsorption and resistance to mammalian cell attachment for over 5 months in an in vitro assay. These new synthetic peptide based antifouling polymers may provide long-term control of surface biofouling in the physiologic, marine, and industrial environments.

  17. Canadian synthetic resins industry

    Energy Technology Data Exchange (ETDEWEB)

    Margeson, J. [Industry Canada, Ottawa, ON (Canada)

    2000-06-01

    The growth of the synthetic resin industry in Canada is described. In 1999 the industry had shipments totalling $6.3 billion and employed about 9,000 people in 105 establishments. The industry is concentrated in Alberta, Ontario and Quebec. Plants in Alberta produce commodity-grade thermoplastic resins from raw materials derived mainly from natural gas, whereas plants in Ontario and Quebec produce both thermoplastic and thermoset resins using raw materials derived from both crude oil and natural gas. Sixty-four per cent of the synthetic reins produced in Canada, worth about $4.1 billion, are exported. This is offset by imports of 68 per cent of domestic consumption, (valued at $5.0 billion) reflecting rationalization and specialization of the resin industry on a continental basis. Process and product technologies used in Canada are up-to-date and licensed from parent or other foreign chemical companies. Capital investment in the Canadian resin industry is lagging behind investment in the United States, however, this is expected to change once the impact of recent investments in the industry in Alberta is reflected in the statistics. A five to seven per cent real average annual growth in world-wide consumption is predicted over the next five years. Growth in North America is projected to be in the three to four per cent range. The Alberta-based component of the industry, being relatively new, is expected to improve its ability to compete globally in commodity thermoplastics. In contrast, the plants in Ontario and Quebec suffer from the fact that they were built prior to the Free Trade Agreement and were designed to satisfy domestic requirements. They are attempting to compensate for their lack of economics of scale by developing strategies to supply niche products. 8 figs.

  18. From Commodity Polymers to Functional Polymers

    Science.gov (United States)

    Xiang, Tao; Wang, Ling-Ren; Ma, Lang; Han, Zhi-Yuan; Wang, Rui; Cheng, Chong; Xia, Yi; Qin, Hui; Zhao, Chang-Sheng

    2014-01-01

    Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outstanding pH-sensitivity and pH-reversibility, antifouling property, antibacterial, and anticoagulant property. Our study opens a route for the functionalization of commodity polymers, which lead to important advances in polymeric materials applications. PMID:24710333

  19. A Study of Gaps in Attack Analysis

    Science.gov (United States)

    2016-10-12

    Kührer, Thomas Hupperich, Christian Rossow, and Thorsten Holz. Exit from Hell? Re- ducing the Impact of Amplification DDoS Attacks. In Proceedings of...Revisiting Network Protocols for DDoS Abuse. In 21st Annual Network and Distributed System Security Symposium, NDSS 2014, San Diego, California, USA

  20. Using an ontology for network attack planning

    CSIR Research Space (South Africa)

    Van Heerden, R

    2016-09-01

    Full Text Available -1 International Journal of Cyber Warfare and Terrorism, vol. 6(3), 65-78 Using an Ontology for Network Attack Planning Renier van Heerden1,2, Peter Chan2 , Louise Leenen2,3 Jacques Theron4 1 Nelson Mandela Metropolitan University, South Africa 2...

  1. Algebraic Side-Channel Attack on Twofish

    Directory of Open Access Journals (Sweden)

    Chujiao Ma

    2017-05-01

    Full Text Available While algebraic side-channel attack (ASCA has been successful in breaking simple cryptographic algorithms, it has never been done on larger or more complex algorithms such as Twofish. Compared to other algorithms that ASCA has been used on, Twofish is more difficult to attack due to the key-dependent S-boxes as well as the complex key scheduling. In this paper, we propose the first algebraic side-channel attack on Twofish, and examine the importance of side-channel information in getting past the key-dependent S-boxes and the complex key scheduling. The cryptographic algorithm and side-channel information are both expressed as boolean equations and a SAT solver is used to recover the key. While algebraic attack by itself is not sufficient to break the algorithm, with the help of side-channel information such as Hamming weights, we are able to correctly solve for 96 bits of the 128 bits key in under 2 hours with known plaintext/ciphertext.

  2. Cyber Attack! Crime or Act of War?

    Science.gov (United States)

    2011-04-13

    informational, or economic.54 Other legal scholars concur in this interpretation, one using the term ― agressive force‖ in lieu of ―armed force‖ but...distributed whiteboard to determine legal responses to online cyber attacks. Internet Research 16, no. 5, (October 20): 475-490. http

  3. Strengthening Crypto-1 Cipher Against Algebraic Attacks

    Directory of Open Access Journals (Sweden)

    Farah Afianti

    2015-08-01

    Full Text Available In the last few years, several studies addressed the problem of data security in Mifare Classic. One of its weaknesses is the low random number quality. This causes SAT solver attacks to have lower complexity. In order to strengthen Crypto-1 against SAT solver attacks, a modification of the feedback function with better cryptographic properties is proposed. It applies a primitive polynomial companion matrix. SAT solvers cannot directly attack the feedback shift register that uses the modified Boolean feedback function, the register has to be split into smaller groups. Experimental testing showed that the amount of memory and CPU time needed were highest when attacking the modified Crypto-1 using the modified feedback function and the original filter function. In addition, another modified Crypto-1, using the modified feedback function and a modified filter function, had the lowest percentage of revealed variables. It can be concluded that the security strength and performance of the modified Crypto-1 using the modified feedback function and the modified filter function are better than those of the original Crypto-1.

  4. Wrap-Attack Pack: Product Packaging Exercise

    Science.gov (United States)

    Lee, Seung Hwan; Hoffman, K. Douglas

    2016-01-01

    Although many marketing courses discuss traditional concepts pertaining to product strategy, concepts specifically relating to packaging are often glossed over. This exercise, "Wrap-Attack Pack," teaches students about the utilitarian and hedonic design elements of packaging. More specifically, the primary objective is to creatively…

  5. Management of an acute asthma attack.

    Science.gov (United States)

    Barnard, Amanda

    2005-07-01

    Despite a more proactive approach to asthma management, which includes an increased range of drugs, wide dissemination of guidelines, and the use of asthma action plans, an acute severe asthma attack is one of the most common emergencies a general practitioner will encounter. This article discusses the management of an acute asthma attack in the general practice setting. Assessment of severity is vital and can be ascertained quite quickly with a brief history and rapid physical examination. It is important to remember that wheeze is an unreliable indicator of the severity of attack and may be absent in severe asthma. The cornerstones of treatment are oxygen and inhaled beta 2 agonists. Beta 2 agonists can be given continuously in severe life threatening asthma. Early administration of systemic steroids is important. Patients discharged to home after treatment of an asthma attack require close follow up including beta 2 agonists for symptom control, review of medications including a consideration of a short course of oral steroids, a written asthma action plan and detailed advice about what to do in case of deterioration in the next 24 hours. They should be reviewed in 24-48 hours.

  6. Understand Your Risk of Heart Attack

    Science.gov (United States)

    ... other risk factors. Overweight and obese adults with risk factors for cardiovascular disease such as high blood pressure, high cholesterol, ... over 40, or if you have multiple risk factors, work especially closely with ... cardiovascular disease. Heart attack prevention should begin early in ...

  7. Afghanistan: Green-on-Blue Attacks

    Science.gov (United States)

    2013-05-02

    spike-insider-attacks- stress- ramadan - fasting , 24 August 2012 37 Yousafzai, Sami and Moreau, Ron, http://www.thedailybeast.com/newsweek/2012/08/26...Ramazan.” “And so the daily pressures that are on some of these [Afghan] troops, compounded by the sacrifice associated with fasting , the nature of

  8. Survival of child after lion attack

    Science.gov (United States)

    Dabdoub, Carlos F.; Dabdoub, Carlos B.; Chavez, Mario; Molina, Felipe

    2013-01-01

    Background: Injuries to humans caused by attacks from large predators are very rare, especially in the United States, Europe, or Latin America. A few cases were reported on accidents in zoos or animal farms, being very uncommon in children. The purposes of this report include describing the case of a child who sustained an attack by a lion named “Bang-Bang”, which resulted in injuries to the head, chest, and abdomen, as well as the subsequent neurosurgical treatment and providing a review of the literature. Case Description: We report the case of an 8-year-old boy who was attacked by a lion during a circus show. The patient underwent an emergent neurosurgical procedure, including parietal craniectomy, cleaning, and extensive surgical debridement of the wounds. Despite open severe head trauma with brain damage as well as thorax and abdomen trauma, the child survived, with minimal neurological sequelae. Conclusions: Human injury resulting from encounters with nondomesticated animals is increasingly rising throughout the world. This case highlights the potentially violent and aggressive nature of wild mammals held in captivity. Unusual wild animal attacks and the complex injuries that result may pose a challenge to surgeons practicing in resource-limited settings. In this sense, the best treatment in the mentioned case is the prevention of human injuries by these animals. In addition, to attend to these infrequent cases, the authors emphasize the importance of a multidisciplinary approach to achieve the best cosmetic and functional results. PMID:23869277

  9. Shark Attack! Sinking Your Teeth into Anatomy.

    Science.gov (United States)

    House, Herbert

    2002-01-01

    Presents a real life shark attack story and studies arm reattachment surgery to teach human anatomy. Discusses how knowledge of anatomy can be put to use in the real world and how the arm functions. Includes teaching notes and suggestions for classroom management. (YDS)

  10. Attack Classification Schema for Smart City WSNs

    Directory of Open Access Journals (Sweden)

    Victor Garcia-Font

    2017-04-01

    Full Text Available Urban areas around the world are populating their streets with wireless sensor networks (WSNs in order to feed incipient smart city IT systems with metropolitan data. In the future smart cities, WSN technology will have a massive presence in the streets, and the operation of municipal services will be based to a great extent on data gathered with this technology. However, from an information security point of view, WSNs can have failures and can be the target of many different types of attacks. Therefore, this raises concerns about the reliability of this technology in a smart city context. Traditionally, security measures in WSNs have been proposed to protect specific protocols in an environment with total control of a single network. This approach is not valid for smart cities, as multiple external providers deploy a plethora of WSNs with different security requirements. Hence, a new security perspective needs to be adopted to protect WSNs in smart cities. Considering security issues related to the deployment of WSNs as a main data source in smart cities, in this article, we propose an intrusion detection framework and an attack classification schema to assist smart city administrators to delimit the most plausible attacks and to point out the components and providers affected by incidents. We demonstrate the use of the classification schema providing a proof of concept based on a simulated selective forwarding attack affecting a parking and a sound WSN.

  11. Attack Classification Schema for Smart City WSNs.

    Science.gov (United States)

    Garcia-Font, Victor; Garrigues, Carles; Rifà-Pous, Helena

    2017-04-05

    Urban areas around the world are populating their streets with wireless sensor networks (WSNs) in order to feed incipient smart city IT systems with metropolitan data. In the future smart cities, WSN technology will have a massive presence in the streets, and the operation of municipal services will be based to a great extent on data gathered with this technology. However, from an information security point of view, WSNs can have failures and can be the target of many different types of attacks. Therefore, this raises concerns about the reliability of this technology in a smart city context. Traditionally, security measures in WSNs have been proposed to protect specific protocols in an environment with total control of a single network. This approach is not valid for smart cities, as multiple external providers deploy a plethora of WSNs with different security requirements. Hence, a new security perspective needs to be adopted to protect WSNs in smart cities. Considering security issues related to the deployment of WSNs as a main data source in smart cities, in this article, we propose an intrusion detection framework and an attack classification schema to assist smart city administrators to delimit the most plausible attacks and to point out the components and providers affected by incidents. We demonstrate the use of the classification schema providing a proof of concept based on a simulated selective forwarding attack affecting a parking and a sound WSN.

  12. Plant defences against herbivore and insect attack

    Science.gov (United States)

    Plants deploy a number of defences against attack by insects and other herbivores. Direct defence is conferred by plant products and structures that deter or kill the herbivores. Chemical toxins and deterrents vary widely among plant species, and some typical toxins include alkaloids, terpenoids, st...

  13. Rhode Island School Terrorist Attack Preparedness

    Science.gov (United States)

    Dube, Michael W. M.

    2012-01-01

    This study examined the state of safety and terrorist attack preparedness in Rhode Island Schools as determined by Rhode Island school leader perceptions. The study is descriptive in nature as it gathers data to describe a particular event or situation. Using a researcher generated survey based on terrorist preparedness guidelines and suggestions…

  14. Intrusion-Tolerant Replication under Attack

    Science.gov (United States)

    Kirsch, Jonathan

    2010-01-01

    Much of our critical infrastructure is controlled by large software systems whose participants are distributed across the Internet. As our dependence on these critical systems continues to grow, it becomes increasingly important that they meet strict availability and performance requirements, even in the face of malicious attacks, including those…

  15. Association between Terror Attacks and Suicide Attempts

    Science.gov (United States)

    Weizman, Tal; Yagil, Yaron; Schreiber, Shaul

    2009-01-01

    Based on Durkheim's "Control theory," we explored the association between frequency of terror attacks in Israel and the frequency of suicide attempts admitted to the Emergency Room of a major general hospital in Tel-Aviv (1999-2004). Analysis of the six-year study period as a whole revealed no significant correlation between the…

  16. An Adaptive Approach for Defending against DDoS Attacks

    Directory of Open Access Journals (Sweden)

    Muhai Li

    2010-01-01

    Full Text Available In various network attacks, the Distributed Denial-of-Service (DDoS attack is a severe threat. In order to deal with this kind of attack in time, it is necessary to establish a special type of defense system to change strategy dynamically against attacks. In this paper, we introduce an adaptive approach, which is used for defending against DDoS attacks, based on normal traffic analysis. The approach can check DDoS attacks and adaptively adjust its configurations according to the network condition and attack severity. In order to insure the common users to visit the victim server that is being attacked, we provide a nonlinear traffic control formula for the system. Our simulation test indicates that the nonlinear control approach can prevent the malicious attack packets effectively while making legitimate traffic flows arrive at the victim.

  17. Polymeric drugs: Advances in the development of pharmacologically active polymers

    Science.gov (United States)

    Li, Jing; Yu, Fei; Chen, Yi; Oupický, David

    2015-01-01

    Synthetic polymers play a critical role in pharmaceutical discovery and development. Current research and applications of pharmaceutical polymers are mainly focused on their functions as excipients and inert carriers of other pharmacologically active agents. This review article surveys recent advances in alternative pharmaceutical use of polymers as pharmacologically active agents known as polymeric drugs. Emphasis is placed on the benefits of polymeric drugs that are associated with their macromolecular character and their ability to explore biologically relevant multivalency processes. We discuss the main therapeutic uses of polymeric drugs as sequestrants, antimicrobials, antivirals, and anticancer and anti-inflammatory agents. PMID:26410809

  18. Glossary of Class Names of Polymers Based on Chemical Structure and Molecular Architecture (IUPAC Recommendations 2009

    Directory of Open Access Journals (Sweden)

    Jarm, V.

    2012-03-01

    Full Text Available This IUPAC's document classifies 111 polymer classes into three groups according to their chemical structure and molecular architecture. For each class, its name, short definition, its characteristic structural feature, an example, and relations to other polymer classes, are given. As the first classification for numerous commonly used polymers (organic, inorganic, synthetic, natural this document improves the knowledge and communication in the field.

  19. Bio- and chemocatalysis cascades as a bridge between biology and chemistry for green polymer synthesis.

    Science.gov (United States)

    Marszałek-Harych, Aleksandra; Jędrzkiewicz, Dawid; Ejfler, Jolanta

    2017-01-01

    The development and integration of bio- and chemocatalytic processes to convert renewable or biomass feedstocks into polymers is a vibrant field of research with enormous potential for environmental protection and the mitigation of global warming. Here, we review the biotechnological and chemical synthetic strategies for producing platform monomers from bio-based sources and transforming them into eco-polymers. We also discuss their advanced bio-application using the example of polylactide (PLA), the most valuable green polymer on the market.

  20. Recovery of human remains after shark attack.

    Science.gov (United States)

    Byard, Roger W; James, Ross A; Heath, Karen J

    2006-09-01

    Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim.

  1. Biodegradable Polymer Membranes Applied in Guided Bone/Tissue Regeneration: A Review

    Directory of Open Access Journals (Sweden)

    Jiaolong Wang

    2016-03-01

    Full Text Available Polymer membranes have been widely used in guided tissue regeneration (GTR and guided bone regeneration (GBR. In this review, various commercially available membranes are described. Much attention is paid to the recent development of biodegradable polymers applied in GTR and GBR, and the important issues of biodegradable polymeric membranes, including their classification, latest experimental research and clinical applications, as well as their main challenges are addressed. Herein, natural polymers, synthetic polymers and their blends are all introduced. Pure polymer membranes are biodegradable and biocompatible, but they lack special properties such as antibacterial properties, osteoconductivity, and thus polymer membranes loaded with functional materials such as antibacterial agents and growth factors show many more advantages and have also been introduced in this review. Despite there still being complaints about polymer membranes, such as their low mechanical properties, uncontrollable degradation speed and some other drawbacks, these problems will undoubtedly be conquered and biodegradable polymers will have more applications in GTR and GBR.

  2. Imaging with Synthetic Aperture Radar

    CERN Document Server

    Massonnet, Didier

    2008-01-01

    Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

  3. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  4. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  5. Analysis of Intrusion Detection and Attack Proliferation in Computer Networks

    Science.gov (United States)

    Rangan, Prahalad; Knuth, Kevin H.

    2007-11-01

    One of the popular models to describe computer worm propagation is the Susceptible-Infected (SI) model [1]. This model of worm propagation has been implemented on the simulation toolkit Network Simulator v2 (ns-2) [2]. The ns-2 toolkit has the capability to simulate networks of different topologies. The topology studied in this work, however, is that of a simple star-topology. This work introduces our initial efforts to learn the relevant quantities describing an infection given synthetic data obtained from running the ns-2 worm model. We aim to use Bayesian methods to gain a predictive understanding of how computer infections spread in real world network topologies. This understanding would greatly reinforce dissemination of targeted immunization strategies, which may prevent real-world epidemics. The data consist of reports of infection from a subset of nodes in a large network during an attack. The infection equation obtained from [1] enables us to derive a likelihood function for the infection reports. This prior information can be used in the Bayesian framework to obtain the posterior probabilities for network properties of interest, such as the rate at which nodes contact one another (also referred to as contact rate or scan rate). Our preliminary analyses indicate an effective spread rate of only 1/5th the actual scan rate used for a star-type of topology. This implies that as the population becomes saturated with infected nodes the actual spread rate will become much less than the scan rate used in the simulation.

  6. Engineering and Applications of DNA-Grafting Polymer Materials.

    Science.gov (United States)

    Peng, Lu; Wu, Cuichen; You, Mingxu; Han, Da; Chen, Yan; Fu, Ting; Ye, Mao; Tan, Weihong

    2013-05-01

    The emergence of hybrid materials combining biomacromolecules and organic polymers has received broad attention based on their potential applications in chemical, biological and materials sciences. Among different coupling strategies, the grafting of oligonucleotides to organic polymers as side chains by covalent bonds provides a novel platform whereby the properties of both oligonucleotides and polymer backbone are integrated, manipulated and optimized for various applications. In this review, we give the perspective on this specific type of DNA polymer hybrid materials , using selected examples with emphasis on bioanalysis, biomedicine and stimuli-responsive materials. It is expected the success of DNA-grafting polymers will not only impact the frabication of novel bimolecule incorporated materials, but also will influence how the properties of synthetic materials are tailored using different functional groups.

  7. Phenothiazine based polymers for energy and data storage application

    Energy Technology Data Exchange (ETDEWEB)

    Golriz, Seyed Ahmad Ali

    2013-03-15

    My work described in the current thesis is focused on the synthesis and characterization of polymers with phenothiazine pendant moieties. Phenothiazine and its derivatives are small redox units with reversible redox and optical properties. The crucial aspect about phenothiazine is the formation of stable radical cation in the oxidized state. Therefore, phenothiazine derivatives are useful as bistable molecules which can be switched between two stable redox states which in addition are accompanied by a change in color. Within the scope of this thesis, the synthetic approach to a new type of phenothiazine polymers by radical polymerization is described. In this context, phenothiazine derivatives were attached to aliphatic and aromatic backbones. Two synthetic routes were studied; one starting from a double bond monomer and the other from an amine containing monomer for post-functionalization with activated ester polymers. Both synthetic routes offer simple and effective approaches to obtain polymers with redox functionality. Polymers with phenothiazine redox functionality are promising candidates as cathode active materials due to their electron donating properties. In order to prove their applicability and examine their performance, phenothiazine polymers were implemented as electrode material in battery cells. The phenothiazine polymers possess decent charging capacities between 50 and 90 Ah/kg at charging rates 5 to 10 times faster than conventional lithium batteries. With respect to long-term charging and discharging, phenothiazine baring polymers are very robust for over more than 500 charge-discharge cycles. It appeared that the stability depends strongly on the formation and the stabilization of the radical cation which is formed by reversible oxidation of the phenothiazine moieties. Long alkyl spacers between the backbone and the phenothiazine moiety help to stabilize the radical cation species and increase the life time of the battery regarding the number of

  8. Words Mean Things: The Case for Information System Attack and Control System Attack

    Science.gov (United States)

    2008-10-31

    FINAL 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Words Mean Things: The Case for Information System Attack and Control System...Standard Form 298 (Rev. 8-98) NAVAL WAR COLLEGE Newport, R.I. WORDS MEAN THINGS: THE CASE FOR INFORMATION SYSTEM ATTACK AND... words , the DepSecDef definition acknowledges the existence of a new domain, but strongly implies the accepted definition of CNO is sufficient to

  9. Chosen-name attacks: An overlooked class of type-flaw attacks

    OpenAIRE

    Ceelen, Pieter; Mauw, Sjouke; Radomirovic, Sasa

    2008-01-01

    In the context of Dolev-Yao style analysis of security protocols, we consider the capability of an intruder to dynamically choose and assign names to agents. This capability has been overlooked in all significant protocol verification frameworks based on formal methods. We identify and classify new type-flaw attacks arising from this capability. Several examples of protocols that are vulnerable to this type of attack are given, including Lowe’s modification of KSL. The consequences for automa...

  10. Polymer nanocomposites: polymer and particle dynamics

    KAUST Repository

    Kim, Daniel

    2012-01-01

    Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has been hypothesized that these unusual properties result from fast diffusion of the nanostructures in the host polymer, which facilitates polymer chain relaxation by constraint release and other processes. In this study, the effects of addition of sterically stabilized inorganic nanoparticles to entangled cis-1,4-polyisoprene and polydimethylsiloxane on the overall rheology of nanocomposites are discussed. In addition, insights about the relaxation of the host polymer chains and transport properties of nanoparticles in entangled polymer nanocomposites are presented. The nanoparticles are found to act as effective plasticizers for their entangled linear hosts, and below a critical, chemistry and molecular-weight dependent particle volume fraction, lead to reduced viscosity, glass transition temperature, number of entanglements, and polymer relaxation time. We also find that the particle motions in the polymer host are hyperdiffusive and at the nanoparticle length scale, the polymer host acts like a simple, ideal fluid and the composites\\' viscosity rises with increasing particle concentration. © 2012 The Royal Society of Chemistry.

  11. EXPERIMENTAL STUDY OF OSTEOINTERGRATION OF SYNTHETIC MATERIAL POLYTETRAFLUOROETHYLENE IMPLANTED IN BONE

    Directory of Open Access Journals (Sweden)

    V. N. Trezubov

    2010-01-01

    Full Text Available The authors presented the results of experimental study devoted the examination of features of synthetic polymer polytetrafluoroethylene (ePTFE implanted in the bone. It was determined that ePTFE with 70% porosity has the more marked osteointegration and can be recommended for clinical use.

  12. Synthesis of a naphthalene-hydroxynaphthalene polymer model compound

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-02

    The objective of this project was the synthesis of one pound of a new naphthalene-hydroxynaphthalene polymer model compound for use in coal combustion studies. Since this compound was an unreported compound, this effort also required the development of a synthetic route to this compound (including routes to the unique and unreported intermediates leading to its synthesis).

  13. Nonlinear optical properties of rigid-rod polymers

    Science.gov (United States)

    Trimmer, Mark S.; Wang, Ying

    1992-01-01

    The purpose of this research project was to integrate enhanced third order nonlinear optical (NLO) properties, especially high x(exp (3)) (greater than 10(exp -8) esu), into Maxdem's novel conjugated rigid-rod polymers while retaining their desirable processing, mechanical, and thermal properties. This work primarily involved synthetic approaches to optimized materials.

  14. Polymers application in proton exchange membranes for fuel cells (PEMFCs)

    Science.gov (United States)

    Walkowiak-Kulikowska, Justyna; Wolska, Joanna; Koroniak, Henryk

    2017-07-01

    This review presents the most important research on alternative polymer membranes with ionic groups attached, provides examples of materials with a well-defined chemical structure that are described in the literature. Furthermore, it elaborates on the synthetic methods used for preparing PEMs, the current status of fuel cell technology and its application. It also briefly discusses the development of the PEMFC market.

  15. Potential polymer concrete heat exchanger tubes for corrosive environments

    Energy Technology Data Exchange (ETDEWEB)

    Fontana, J.J.; Reams, W.; Cheng, H.C.

    1986-11-01

    It has long been known that carbon steel exposed to some geothermal brines is aggressively attacked, and large corrosion allowances must be made in the design of piping used in such environments. In addition, scaling of the pipes reduces the flow through within a short period of time. Several high temperature polymer concretes have been developed which can be used as non-corrosive liner materials. In addition, polymer concretes with high thermal conductivities have been developed which may be used as heat exchanger tubes for geothermal brines. Studies have indicated that polymer concretes will not scale as rapidly as carbon steel does, thus making them attractive alternatives for heat exchanger tubes. Thin walled, thermally conductive polymer concrete tubes have been made that can withstand pressures >4.1 MPa at 150/sup 0/C without leaking. Continuing studies are being made to characterize these materials and evaluate them for heat exchanger applications.

  16. Flow Control of the Stingray UAV at Low Angles of Attack

    Science.gov (United States)

    Farnsworth, John; Vaccaro, John; Amitay, Michael

    2007-11-01

    The effectiveness of active flow control, via synthetic jets and steady blowing jets, on the aerodynamic performance of the Stingray UAV was investigated experimentally in a wind tunnel. Global flow measurements were conducted using a six component sting balance, static pressure, and Particle Image Velocimetry (PIV) measurements. Using active control for trimming the Stingray UAV in pitch and roll at low angles of attack has similar effects to those with conventional control effectors. The synthetic jets were able to alter the local streamlines through the formation of a quasi-steady interaction region on the suction surface of the vehicle's wing. Phase locked data were acquired to provide insight into the growth, propagation, and decay of the synthetic jet impulse and its interaction with the cross-flow. The changes induced on the moments and forces can be proportionally controlled by either changing the momentum coefficient or by driving the synthetic jets with a pulse modulation waveform. This can lead the way for future development of closed-loop control models.

  17. Synthetic Jet Actuator Performance Enhancement

    Science.gov (United States)

    Pikcilingis, Lucia; Housley, Kevin; Whalen, Ed; Amitay, Michael; Rensselaer Polytechnic Institute Collaboration; Boeing Company Collaboration

    2014-11-01

    Over the last 20 years synthetic jets have been studied as a means for aerodynamic flow control. Specifically, synthetic jets provide momentum transfer with zero-net mass flux, which has been proven to be effective for controlling flow fields. A synthetic jet is created by the periodic formation of vortex rings at its orifice due to the periodic motion of a piezoelectric disk(s). The present study seeks to optimize the performance of a synthetic jet actuator by utilizing different geometrical parameters such as disk thickness, orifice width and length, cavity height and cavity diameter, and different input parameters such as voltage and frequency. Experiments were conducted using a synthetic jet apparatus designed for various geometrical parameters utilizing a dual disk configuration. Velocity and temperature measurements were acquired at the center of the synthetic jet orifice using a temperature compensated hotwire and thermocouple probe. The disk displacement was measured at the center of the disk with a laser displacement sensor. It was shown that the synthetic jet actuators are capable of exceeding peak velocities of 200 m/s with a relatively large orifice. Data suggests that jet velocities greater than 200 m/s are attainable.

  18. Spicing things up: synthetic cannabinoids.

    Science.gov (United States)

    Spaderna, Max; Addy, Peter H; D'Souza, Deepak Cyril

    2013-08-01

    Recently, products containing synthetic cannabinoids, collectively referred to as Spice, are increasingly being used recreationally. The availability, acute subjective effects-including self-reports posted on Erowid-laboratory detection, addictive potential, and regulatory challenges of the Spice phenomenon are reviewed. Spice is sold under the guise of potpourri or incense. Unlike delta-9-tetrahydrocannabinol, the synthetic cannabinoids present in Spice are high-potency, high-efficacy, cannabinoid receptor full agonists. Since standard urine toxicology does not test for the synthetic cannabinoids in Spice, it is often used by those who want to avoid detection of drug use. These compounds have not yet been subjected to rigorous testing in humans. Acute psychoactive effects include changes in mood, anxiety, perception, thinking, memory, and attention. Adverse effects include anxiety, agitation, panic, dysphoria, psychosis, and bizarre behavior. Psychosis outcomes associated with Spice provide additional data linking cannabinoids and psychosis. Adverse events necessitating intervention by Poison Control Centers, law enforcement, emergency responders, and hospitals are increasing. Despite statutes prohibiting the manufacture, distribution, and sale of Spice products, manufacturers are replacing banned compounds with newer synthetic cannabinoids that are not banned. There is an urgent need for better research on the effects of synthetic cannabinoids to help clinicians manage adverse events and to better understand cannabinoid pharmacology in humans. The reported psychosis outcomes associated with synthetic cannabinoids contribute to the ongoing debate on the association between cannabinoids and psychosis. Finally, drug detection tests for synthetic cannabinoids need to become clinically available.

  19. Spicing thing up: Synthetic cannabinoids

    Science.gov (United States)

    Spaderna, Max; Addy, Peter H; D’Souza, Deepak Cyril

    2013-01-01

    Rationale Recently, products containing synthetic cannabinoids, collectively referred to as Spice, are increasingly being used recreationally. Objectives The availability, acute subjective effects—including self-reports posted on Erowid—laboratory detection, addictive potential, and regulatory challenges of the Spice phenomenon are reviewed. Results Spice is sold under the guise of potpourri or incense. Unlike THC, the synthetic cannabinoids present in Spice are high-potency, high-efficacy, cannabinoid-receptor full agonists. Since standard urine toxicology does not test for the synthetic cannabinoids in Spice, it is often used by those who want to avoid detection of drug use. These compounds have not yet been subjected to rigorous testing in humans. Acute psychoactive effects include changes in mood, anxiety, perception, thinking, memory, and attention. Adverse effects include anxiety, agitation, panic, dysphoria, psychosis, and bizarre behavior. Psychosis outcomes associated with Spice provide additional data linking cannabinoids and psychosis. Adverse events necessitating intervention by Poison Control Centers, law enforcement, emergency responders, and hospitals are increasing. Despite statutes prohibiting the manufacture, distribution, and sale of Spice products, manufacturers are replacing banned compounds with newer synthetic cannabinoids that are not banned. Conclusions There is an urgent need for better research on the effects of synthetic cannabinoids to help clinicians manage adverse events and to better understand cannabinoid pharmacology in humans. The reported psychosis outcomes associated with synthetic cannabinoids contribute to the ongoing debate on the association between cannabinoids and psychosis. Finally, drug-detection tests for synthetic cannabinoids need to become clinically available. PMID:23836028

  20. Diverticulitis Diet: Can Certain Foods Trigger an Attack?

    Science.gov (United States)

    ... there trigger foods I should avoid to prevent diverticulitis attacks? Answers from Katherine Zeratsky, R.D., L. ... Actually, no specific foods are known to trigger diverticulitis attacks. And no special diet has been proved ...