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Sample records for constitutive polymers biological

  1. Constitutive equations for an electroactive polymer

    NASA Astrophysics Data System (ADS)

    Tixier, Mireille; Pouget, Joël

    2016-07-01

    Ionic electroactive polymers can be used as sensors or actuators. For this purpose, a thin film of polyelectrolyte is saturated with a solvent and sandwiched between two platinum electrodes. The solvent causes a complete dissociation of the polymer and the release of small cations. The application of an electric field across the thickness results in the bending of the strip and vice versa. The material is modeled by a two-phase continuous medium. The solid phase, constituted by the polymer backbone inlaid with anions, is depicted as a deformable porous media. The liquid phase is composed of the free cations and the solvent (usually water). We used a coarse grain model. The conservation laws of this system have been established in a previous work. The entropy balance law and the thermodynamic relations are first written for each phase and then for the complete material using a statistical average technique and the material derivative concept. One deduces the entropy production. Identifying generalized forces and fluxes provides the constitutive equations of the whole system: the stress-strain relations which satisfy a Kelvin-Voigt model, generalized Fourier's and Darcy's laws and the Nernst-Planck equation.

  2. Constitutive Modeling of Piezoelectric Polymer Composites

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Gates, Tom (Technical Monitor)

    2003-01-01

    A new modeling approach is proposed for predicting the bulk electromechanical properties of piezoelectric composites. The proposed model offers the same level of convenience as the well-known Mori-Tanaka method. In addition, it is shown to yield predicted properties that are, in most cases, more accurate or equally as accurate as the Mori-Tanaka scheme. In particular, the proposed method is used to determine the electromechanical properties of four piezoelectric polymer composite materials as a function of inclusion volume fraction. The predicted properties are compared to those calculated using the Mori-Tanaka and finite element methods.

  3. Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

    2004-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

  4. Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

    2001-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

  5. Solid Rocket Fuel Constitutive Theory and Polymer Cure

    NASA Technical Reports Server (NTRS)

    Ream, Robert

    2006-01-01

    Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

  6. Constitutive Modeling of Nanotube-Reinforced Polymer Composites

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Gates, T. S.; Wise, K. E.; Park, C.; Siochi, E. J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube lengths, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyimide composite systems.

  7. Constitutive Modeling of Nanotube-Reinforced Polymer Composites

    NASA Technical Reports Server (NTRS)

    Odegard, G. M.; Gates, T. S.; Wise, K. E.

    2002-01-01

    In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube shapes, sizes, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/LaRC-SI (with a PmPV interface) composite systems, one with aligned SWNTs and the other with three-dimensionally randomly oriented SWNTs. The Young's modulus and shear modulus have been calculated for the two systems for various nanotube lengths and volume fractions.

  8. Constitutive equation for polymer networks with phonon fluctuations.

    PubMed

    Hansen, Rasmus; Skov, Anne Ladegaard; Hassager, Ole

    2008-01-01

    Recent research by Xing [Phys. Rev. Lett. 98, 075502 (2007)] has provided an expression for the Helmholtz free energy related to phonon fluctuations in polymer networks. We extend this result by constructing the corresponding nonlinear constitutive equation, usable for entirely general, volume conserving deformation fields. Constitutive equations for the sliplink model and the tube model are derived and the three models are examined by comparison with each other and with data from Xu and Mark [Rubber Chem. Technol. 63, 276 (1990)] and Wang and Mark [J. Polym. Sci., Part B: Polym. Phys. 30, 801 (1992)]. Elastic moduli are derived for the three models and compared with the moduli determined from the chemical stoichiometry. We conclude that the sliplink model and the phonon fluctuation model are relatively consistent with each other and with the data. The tube model seems consistent neither with the other models nor with the data.

  9. Rate dependent constitutive models for fiber reinforced polymer composites

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.

    1990-01-01

    A literature survey was conducted to assess the state-of-the-art in rate dependent constitutive models for continuous fiber reinforced polymer matrix composite (PMC) materials. Several recent models which include formulations for describing plasticity, viscoelasticity, viscoplasticity, and rate-dependent phenomenon such as creep and stress relaxation are outlined and compared. When appropriate, these comparisons include brief descriptions of the mathematical formulations, the test procedures required for generating material constants, and details of available data comparing test results to analytical predictions.

  10. Probabilistic estimation of the constitutive parameters of polymers

    NASA Astrophysics Data System (ADS)

    Foley, J. R.; Jordan, J. L.; Siviour, C. R.

    2012-08-01

    The Mulliken-Boyce constitutive model predicts the dynamic response of crystalline polymers as a function of strain rate and temperature. This paper describes the Mulliken-Boyce model-based estimation of the constitutive parameters in a Bayesian probabilistic framework. Experimental data from dynamic mechanical analysis and dynamic compression of PVC samples over a wide range of strain rates are analyzed. Both experimental uncertainty and natural variations in the material properties are simultaneously considered as independent and joint distributions; the posterior probability distributions are shown and compared with prior estimates of the material constitutive parameters. Additionally, particular statistical distributions are shown to be effective at capturing the rate and temperature dependence of internal phase transitions in DMA data.

  11. Biological activity of ionene polymers

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1973-01-01

    Ionene polymers are polyammonium salts with positive nitrogens in the backbone, resulting from the polycondensation of diamines with dihalides or from the polycondensation of halo amines. The mechanism of formation of ionene polymers of different structures and their biological activity is reviewed. The antimicrobial and antifungal properties are compared with low molecular weight ammonium salts. Ionenes were found to combine with DNA by means of ionic bonds to yield similar complexes to those obtained with polyamines (spermine and spermidine). They also combine with nerve cell receptors and exercise a more powerful and longer duration ganglionic blocking action than their monomeric analogs. The antiheparin activity of ionenes and the thromboresistance of elastomeric ionene heparin coatings is described. The enhanced biological activity of ionenes as compared with low molecular weight compounds is attributed to a cooperative effect of a large number of positive charges on the polymeric chains.

  12. Biological activity of ionene polymers

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1973-01-01

    Ionene polymers are polyammonium salts with positive nitrogens in the backbone, resulting from the polycondensation of diamines with dihalides or from the polycondensation of halo amines. The mechanism of formation of ionene polymers of different structures and their biological activity is reviewed. The antimicrobial and antifungal properties are compared with low molecular weight ammonium salts. Ionenes were found to combine with DNA by means of ionic bonds to yield similar complexes to those obtained with polyamines (spermine and spermidine). They also combine with nerve cell receptors and exercise a more powerful and longer duration ganglionic blocking action than their monomeric analogs. The antiheparin activity of ionenes and the thromboresistance of elastomeric ionene heparin coatings is described. The enhanced biological activity of ionenes as compared with low molecular weight compounds is attributed to a cooperative effect of a large number of positive charges on the polymeric chains.

  13. [Relationship between system biology and traditional Chinese constitutional medicine].

    PubMed

    Zhang, Wei-Rong; Li, Jing

    2006-11-01

    Life system and medicine are both complex systems. Recently, traditional biologists have acquired tremendous data from high-speed development of all kinds of species group. However, how to use these data to interpret the mechanisms of diseases and health has become the research target of current investigators. The booms of system biology provide new thought and research methods to tackle this problem. This paper emphasizes the relationship between system biology and traditional Chinese constitutional medicine.

  14. Polymer-induced compression of biological hydrogels

    NASA Astrophysics Data System (ADS)

    Datta, Sujit; Preska Steinberg, Asher; Ismagilov, Rustem

    Hydrogels - such as mucus, blood clots, and the extracellular matrix - provide critical functions in biological systems. However, little is known about how their structure is influenced by many of the polymeric materials they come into contact with regularly. Here, we focus on one critically important biological hydrogel: colonic mucus. While several biological processes are thought to potentially regulate the mucus hydrogel structure, the polymeric composition of the gut environment has been ignored. We use Flory-Huggins solution theory to characterize polymer-mucus interactions. We find that gut polymers, including those small enough to penetrate the mucus hydrogel, can in fact alter mucus structure, changing its equilibrium degree of swelling and forcing it to compress. The extent of compression increases with increasing polymer concentration and size. We use experiments on mice to verify these predictions with common dietary and therapeutic gut polymers. Our results provide a foundation for investigating similar, previously overlooked, polymer-induced effects in other biological hydrogels.

  15. Mechanics of biological polymer composites

    NASA Astrophysics Data System (ADS)

    Lomakin, Joseph

    2009-12-01

    displayed a darker coloration and significantly increased n of 0.0470.004, suggesting both cuticles to be less cross-linked, a finding consistent with reduced beta-alanine metabolism. Suppression of the tanning enzyme laccase2 (TcLac2) resulted in a pale cuticle with an n of 0.043+/-0.005, implicating laccases in the formation of both pigments and cross-links during sclerotization. Cuticular cross-linking was increased and n decreased with decreased expression of structural proteins, CP10 and CP20. This work establishes n as an important novel parameter for confirming metabolic pathways within load bearing tissues and for understanding structure function relationships within biological polymer composites. Additionally, Tribolium castaneum elytral indentation modulus (800+/-200 MPa) was determined by nanoindentation and a 4nm regular hexagonal pattern on the dorsal side of elytra investigated via scanning, transmission and atomic microscopy. Based on studied biological materials, the combination of rigid macromolecules immersed in a ductile matrix was found to be significant in achieving exceptional mechanical performance. Inspired by this biological design principle, the synthesis, properties and structure of Poly(ethylene glycol) diacrylate/agarose semi-interpenetrating network hydrogels were explored. The resulting novel composite materials were 9x stiffer than agarose and 5x tougher than PEGDA alone and showed good biocompatibility, suggesting promise as a scaffold material for tissue engineering constructs for cartilage regeneration.

  16. Constitutive Modeling of Nanotube/Polymer Composites with Various Nanotube Orientations

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Gates, Thomas S.

    2002-01-01

    In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT) with various orientations with respect to the bulk material coordinates. A nanotube, the local polymer adjacent to the nanotube, and the nanotube/polymer interface have been modeled as an equivalent-continuum fiber by using an equivalent-continuum modeling method. The equivalent-continuum fiber accounts for the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composite. As an example, the proposed approach is used for the constitutive modeling of a SWNT/LaRC-SI (with a PmPV interface) composite system, with aligned nanotubes, three-dimensionally randomly oriented nanotubes, and nanotubes oriented with varying degrees of axisymmetry. It is shown that the Young s modulus is highly dependent on the SWNT orientation distribution.

  17. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  18. Nanostructure Control of Biologically Inspired Polymers

    NASA Astrophysics Data System (ADS)

    Rosales, Adrianne Marie

    Biological polymers, such as polypeptides, are responsible for many of life's most sophisticated functions due to precisely evolved hierarchical structures. These protein structures are the result of monodisperse sequences of amino acids that fold into well-defined chain shapes and tertiary structures. Recently, there has been much interest in the design of such sequence-specific polymers for materials applications in fields ranging from biotechnology to separations membranes. Non-natural polymers offer the stability and robustness necessary for materials applications; however, our ability to control monomer sequence in non-natural polymers has traditionally operated on a much simpler level. In addition, the relationship between monomer sequence and self-assembly is not well understood for biological molecules, much less synthetic polymers. Thus, there is a need to explore self-assembly phase space with sequence using a model system. Polypeptoids are non-natural, sequence-specific polymers that offer the opportunity to probe the effect of sequence on self-assembly. A variety of monomer interactions have an impact on polymer properties, such as chirality, hydrophobicity, and electrostatic interactions. Thus, a necessary starting point for this project was to investigate monomer sequence effects on the bulk properties of polypeptoid homopolymers. It was found that several polypeptoids have experimentally accessible melting transitions that are dependent on the choice of side chains, and it was shown that this transition is tuned by the incorporation of "defects" or a comonomer. The polypeptoid chain shape is also controlled with the choice of monomer and monomer sequence. By using at least 50% monomers with bulky, chiral side chains, the polypeptoid backbone is sterically twisted into a helix, and as found for the first time in this work, the persistence length is increased. However, this persistence length, which is a measure of the stiffness of the polymer, is

  19. Systematic coarse graining flowing polymer melts: thermodynamically guided simulations and resulting constitutive model.

    PubMed

    Iig, Patrick

    2011-01-01

    Complex fluids, such as polymers, colloids, liquid-crystals etc., show intriguing viscoelastic properties, due to the complicated interplay between flow-induced structure formation and dynamical behavior. Starting from microscopic models of complex fluids, a systematic coarse-graining method is presented that allows us to derive closed-form and thermodynamically consistent constitutive equations for such fluids. Essential ingredients of the proposed approach are thermodynamically guided simulations within a consistent coarse-graining scheme. In addition to this new type of multiscale simulations, we reconstruct the building blocks that constitute the thermodynamically consistent coarse-grained model. We illustrate the method for low-molecular polymer melts, which are subject to different imposed flow fields like planar shear and different elongational flows. The constitutive equation for general flow conditions we obtain shows rheological behavior including shear thinning, normal stress differences, and elongational viscosities in good agreement with reference results.

  20. Biologically Inspired Technology Using Electroactive Polymers (EAP)

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2006-01-01

    Evolution allowed nature to introduce highly effective biological mechanisms that are incredible inspiration for innovation. Humans have always made efforts to imitate nature's inventions and we are increasingly making advances that it becomes significantly easier to imitate, copy, and adapt biological methods, processes and systems. This brought us to the ability to create technology that is far beyond the simple mimicking of nature. Having better tools to understand and to implement nature's principles we are now equipped like never before to be inspired by nature and to employ our tools in far superior ways. Effectively, by bio-inspiration we can have a better view and value of nature capability while studying its models to learn what can be extracted, copied or adapted. Using electroactive polymers (EAP) as artificial muscles is adding an important element to the development of biologically inspired technologies.

  1. Biologically Inspired Technology Using Electroactive Polymers (EAP)

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2006-01-01

    Evolution allowed nature to introduce highly effective biological mechanisms that are incredible inspiration for innovation. Humans have always made efforts to imitate nature's inventions and we are increasingly making advances that it becomes significantly easier to imitate, copy, and adapt biological methods, processes and systems. This brought us to the ability to create technology that is far beyond the simple mimicking of nature. Having better tools to understand and to implement nature's principles we are now equipped like never before to be inspired by nature and to employ our tools in far superior ways. Effectively, by bio-inspiration we can have a better view and value of nature capability while studying its models to learn what can be extracted, copied or adapted. Using electroactive polymers (EAP) as artificial muscles is adding an important element to the development of biologically inspired technologies.

  2. A Micromechanical Constitutive Model of Progressive Crushing in Random Carbon Fiber Polymer Matrix Composites

    SciTech Connect

    Lee, H.K.; Simunovic, S.

    1999-09-01

    A micromechanical damage constitutive model is presented to predict the overall elastoplastic behavior and damage evolution in random carbon fiber polymer matrix composites (RFPCs).To estimate the overall elastoplastic damage responses,an effective yield criterion is derived based on the ensemble-volume averaging process and first-order effects of eigenstrains due to the existence of spheroidal (prolate) fibers.The proposed effective yield criterion,to ether with the assumed overall associative plastic flow rule and hardening law, constitutes the analytical foundation for the estimation of effective elastoplastic behavior of ductile matrix composites.First,an effective elastoplastic constitutive dama e model for aligned fiber-reinforced composites is proposed.A micromechanical damage constitutive model for RFPCs is then developed.The average process over all orientations upon overning constitutive field equations and overall yield function for aligned fiber-reinforced composites i s performed to obtain the constitutive relations and effective yield function of RFPCs.The discrete numerical integration algorithms and the continuum tan ent operator are also presented to implement the proposed dama e constitutive model.The dama e constitutive model forms the basis for the pro ressive crushing in composite structures under impact loading.

  3. A constitutive theory for shape memory polymers: coupling of small and large deformation

    NASA Astrophysics Data System (ADS)

    Tan, Qiao; Liu, Liwu; Liu, Yanju; Leng, Jinsong; Yan, Xiangqiao; Wang, Haifang

    2013-04-01

    At high temperatures, SMPs share attributes like rubber and exhibit long-range reversibility. In contrast, at low temperatures they become very rigid and are susceptible to plastic, only small strains are allowable. But there relatively little literature has considered the unique small stain (rubber phase) and large stain (glass phase) coupling in SMPs when developing the constitutive modeling. In this work, we present a 3D constitutive model for shape memory polymers in both low temperature small strain regime and high temperature large strain regime. The theory is based on the work of Liu et al. [15]. Four steps of SMP's thermomechanical loadings cycle are considered in the constitutive model completely. The linear elastic and hyperelastic effects of SMP in different temperatures are also fully accounted for in the proposed model by adopt the neo-Hookean model and the Generalized Hooke's laws.

  4. Constitutional Isomers of Dendrimer-like Star Polymers: Design, Synthesis and Conformational and Structural Properties

    SciTech Connect

    Pople, John A

    2001-03-22

    The design, synthesis and solution properties of six constitutional isomers of dendrimer-like star polymers is described. Each of the polymers have comparable molecular weights ({approx} 80,000 g/mol), narrow polydispersities (< 1.19) and an identical number of branching junctures (45) and surface hydroxyl functionalities (48). The only difference in the six isomers is the placement of the branching junctures. The polymers are constructed from high molecular weight poly(e-caprolactone) with branching junctures derived from 2,2'-bis(hydroxylmethyl) propionic acid (bis-MPA) emanating from a central core. The use of various generations of dendritic initiators and dendrons coupled with the ring opening polymerization of e-caprolactones allowed a modular approach to the dendrimer-like star polymer isomers. The most pronounced effects on the physical properties/morphology and hydrodynamic volume was for those polymers in which the branching was distributed throughout the sample in a dendrimer-like fashion. The versatility of this approach has provided the possibility of understanding the relationship between architecture and physical properties. Dynamic light scattering and small angle X-ray scattering techniques were used to determine the hydrodynamic radius Rh and radius of gyration Rg respectively. The relationship between Rg and molecular weight was indicative of a compact star-like structure, and did not show advanced bias towards either the dense core or dense shell models. The radial density distribution of the isomers was therefore modeled according to a many arm star polymer, and good agreement was found with experimental measures of Rh/Rg.

  5. Constitutive Modeling and Testing of Polymer Matrix Composites Incorporating Physical Aging at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Veazie, David R.

    1998-01-01

    Advanced polymer matrix composites (PMC's) are desirable for structural materials in diverse applications such as aircraft, civil infrastructure and biomedical implants because of their improved strength-to-weight and stiffness-to-weight ratios. For example, the next generation military and commercial aircraft requires applications for high strength, low weight structural components subjected to elevated temperatures. A possible disadvantage of polymer-based composites is that the physical and mechanical properties of the matrix often change significantly over time due to the exposure of elevated temperatures and environmental factors. For design, long term exposure (i.e. aging) of PMC's must be accounted for through constitutive models in order to accurately assess the effects of aging on performance, crack initiation and remaining life. One particular aspect of this aging process, physical aging, is considered in this research.

  6. The anisotropic mechanical behaviour of electro-spun biodegradable polymer scaffolds: Experimental characterisation and constitutive formulation.

    PubMed

    Limbert, Georges; Omar, Rodaina; Krynauw, Hugo; Bezuidenhout, Deon; Franz, Thomas

    2016-01-01

    Electro-spun biodegradable polymer fibrous structures exhibit anisotropic mechanical properties dependent on the degree of fibre alignment. Degradation and mechanical anisotropy need to be captured in a constitutive formulation when computational modelling is used in the development and design optimisation of such scaffolds. Biodegradable polyester-urethane scaffolds were electro-spun and underwent uniaxial tensile testing in and transverse to the direction of predominant fibre alignment before and after in vitro degradation of up to 28 days. A microstructurally-based transversely isotropic hyperelastic continuum constitutive formulation was developed and its parameters were identified from the experimental stress-strain data of the scaffolds at various stages of degradation. During scaffold degradation, maximum stress and strain in circumferential direction decreased from 1.02 ± 0.23 MPa to 0.38 ± 0.004 MPa and from 46 ± 11 % to 12 ± 2 %, respectively. In longitudinal direction, maximum stress and strain decreased from 0.071 ± 0.016 MPa to 0.010 ± 0.007 MPa and from 69 ± 24 % to 8 ± 2 %, respectively. The constitutive parameters were identified for both directions of the non-degraded and degraded scaffold for strain range varying between 0% and 16% with coefficients of determination r(2)>0.871. The six-parameter constitutive formulation proved versatile enough to capture the varying non-linear transversely isotropic behaviour of the fibrous scaffold throughout various stages of degradation.

  7. High-temperature viscoelastic creep constitutive equations for polymer composites: Homogenization theory and experiments

    SciTech Connect

    Skontorp, A.; Wang, S.S.; Shibuya, Y.

    1994-12-31

    In this paper, a homogenization theory is developed to determine high-temperature effective viscoelastic constitutive equations for fiber-reinforced polymer composites. The homogenization theory approximates the microstructure of a fiber composite, and determine simultaneously effective macroscopic constitutive properties of the composite and the associated microscopic strain and stress in the heterogeneous material. The time-temperature dependent homogenization theory requires that the viscoelastic constituent properties of the matrix phase at elevated temperatures, the governing equations for the composites, and the boundary conditions of the problem be Laplace transformed to a conjugate problem. The homogenized effective properties in the transformed domain are determined, using a two-scale asymptotic expansion of field variables and an averaging procedure. Field solutions in the unit cell are determined from basic and first-order governing equations with the aid of a boundary integral method (BIM). Effective viscoelastic constitutive properties of the composite at elevated temperatures are determined by an inverse transformation, as are the microscopic stress and deformation in the composite. Using this method, interactions among fibers and between the fibers and the matrix can be evaluated explicitly, resulting in accurate solutions for composites with high-volume fraction of reinforcing fibers. Examples are given for the case of a carbon-fiber reinforced thermoplastic polyamide composite in an elevated temperature environment. The homogenization predictions are in good agreement with experimental data available for the composite.

  8. A simplified constitutive model for predicting shape memory polymers deformation behavior

    NASA Astrophysics Data System (ADS)

    Li, Yunxin; Guo, Siu-Siu; He, Yuhao; Liu, Zishun

    2015-12-01

    Shape memory polymers (SMPs) can keep a temporary shape after pre-deformation at a higher temperature and subsequent cooling. When they are reheated, their original shapes can be recovered. Such special characteristics of SMPs make them widely used in aerospace structures, biomedical devices, functional textiles and other devices. Increasing usefulness of SMPs motivates us to further understand their thermomechanical properties and deformation behavior, of which the development of appropriate constitutive models for SMPs is imperative. There is much work in literatures that address constitutive models of the thermo-mechanical coupling in SMPs. However, due to their complex forms, it is difficult to apply these constitutive models in the real world. In this paper, a three-element model with simple form is proposed to investigate the thermo-mechanical small strain (within 10%) behavior of polyurethane under uniaxial tension. Two different cases of heated recovery are considered: (1) unconstrained free strain recovery and (2) stress recovery under full constraint at a strain level fixed during low temperature unloading. To validate the model, simulated and predicted results are compared with Tobushi's experimental results and good agreement can be observed.

  9. Method for separating biological cells. [suspended in aqueous polymer systems

    NASA Technical Reports Server (NTRS)

    Brooks, D. E. (Inventor)

    1980-01-01

    A method for separating biological cells by suspending a mixed cell population in a two-phase polymer system is described. The polymer system consists of droplet phases with different surface potentials for which the cell populations exhibit different affinities. The system is subjected to an electrostatic field of sufficient intensity to cause migration of the droplets with an attendant separation of cells.

  10. Solitons in synthetic and biological polymers

    SciTech Connect

    Bishop, A.R.

    1983-01-01

    Solid state and statistical physics applications of soliton mathematics continue to expand rapidly. The present report describes connections between solid state (e.g. synthetic polymer) and biophysics, with strong nonlinearity playing the unifying role. Striking parallels examined include: analytical (as in the case of self-trapping mechanisms); numerical techniques; experimental implications, applications, and techniques. Conventional solid state probes are at last being devoted to biopolymers but their complexity is demanding new extremes and techniques.

  11. [Latex and synthetic polymers gloves: protective effectiveness against biological risk].

    PubMed

    Balbiani, Lara; Sossai, D

    2008-01-01

    The quick evolution of knowledge about latex and, especially, its effectiveness as protection against biological risks on one hand, and, on the other hand, as trigger of cutaneous, respiratory and sistemic allergic diseases, required a marked distinction between conditions in which latex is necessary and conditions in which latex could be substituted by syntetic polymers. The aim of this study is to verify protective effectiveness of gloves made of syntetic polymers against biological risks compared with latex gloves which until now have been considered as the best protection. Literature review. The most recent studies seem to consider neoprene gloves as the safest protection to replace latex in working activities with high biological risk exposure. The literature review marked the lack of studies exclusively focused on glove permeability towards biological agents. It seems therefore necessary to investigate this topic to validate results and to guarantee a suitable protection to workers daily exposed to biological risk.

  12. Isothermal recovery response and constitutive model of thermoset shape memory polymers

    NASA Astrophysics Data System (ADS)

    Tan, Huifeng; Zhou, Tao; Liu, Yuyan; Lan, Lan

    2012-04-01

    Deformation recovery capability is one of the important indexes to examination shape memory effect of the shape memory polymers (SMPs). And the shape memory characteristic of SMPs is closely related to different phase states and mechanical properties above and below the glass transition temperature (Tg). In this paper, we investigated the strain recovery response of a thermoset shape memory epoxy resin modified by polyurethane (PU) through uniaxial compression experiments under various isothermal conditions and strain rates and developed a "three-phase" constitutive model based on phase transition concept, which including stationary phase, active phase and frozen phase. This model established the mutual transformation relationships between frozen phase and active phase of SMPs by introducing temperature switch function, which presents the stain storage and release process of SMPs under loading and changing temperature environment. Besides, the proposed model represents the SMPs deformation process of viscous hysteresis response by employing the rheological elements description of the three phases. The numerical results agree very well with experiment results of stress-strain response curve of isothermal compression/unloading test, which validated this model can predict the finite deformation behavior of SMPs.

  13. A multi-branch finite deformation constitutive model for a shape memory polymer based syntactic foam

    NASA Astrophysics Data System (ADS)

    Gu, Jianping; Sun, Huiyu; Fang, Changqing

    2015-02-01

    A multi-branch thermoviscoelastic-themoviscoplastic finite deformation constitutive model incorporated with structural and stress relaxation is developed for a thermally activated shape memory polymer (SMP) based syntactic foam. In this paper, the total mechanical deformation of the foam is divided into the components of the SMP and the elastic glass microballoons by using the mixture rule. The nonlinear Adam-Gibbs model is used to describe the structural relaxation of the SMP as the temperature crosses the glass transition temperature (Tg). Further, a multi-branch model combined with the modified Eying model of viscous flow is used to capture the multitude of relaxation processes of the SMP. The deformation of the glass microballoons could be split into elastic and inelastic components. In addition, the phenomenological evolution rule is implemented in order to further characterize the macroscopic post-yield strain softening behaviors of the syntactic foam. A comparison between the numerical simulation and the thermomechanical experiment shows an acceptable agreement. Moreover, a parametric study is conducted to examine the predictability of the model and to provide guidance for reasonable design of the syntactic foam.

  14. Isothermal recovery response and constitutive model of thermoset shape memory polymers

    NASA Astrophysics Data System (ADS)

    Tan, Huifeng; Zhou, Tao; Liu, Yuyan; Lan, Lan

    2011-11-01

    Deformation recovery capability is one of the important indexes to examination shape memory effect of the shape memory polymers (SMPs). And the shape memory characteristic of SMPs is closely related to different phase states and mechanical properties above and below the glass transition temperature (Tg). In this paper, we investigated the strain recovery response of a thermoset shape memory epoxy resin modified by polyurethane (PU) through uniaxial compression experiments under various isothermal conditions and strain rates and developed a "three-phase" constitutive model based on phase transition concept, which including stationary phase, active phase and frozen phase. This model established the mutual transformation relationships between frozen phase and active phase of SMPs by introducing temperature switch function, which presents the stain storage and release process of SMPs under loading and changing temperature environment. Besides, the proposed model represents the SMPs deformation process of viscous hysteresis response by employing the rheological elements description of the three phases. The numerical results agree very well with experiment results of stress-strain response curve of isothermal compression/unloading test, which validated this model can predict the finite deformation behavior of SMPs.

  15. [Constitution of a bank of biological material in the French Gazel cohort: logistical and practical aspects].

    PubMed

    Zins, M; Ozguler, A; Bonenfant, S; Henny, J; Goldberg, M

    2003-02-01

    The Gazel cohort was launched in January 1989 among workers of the French national electricity and gas company to form an open and general purpose epidemiological laboratory. More than 20.000 workers (15.000 men, 5.000 women), aged from 35 to 50 volunteered to participate. One of the objectives of this cohort was the constitution of a bank of biological material aiming to collect and preserve various biological samples (serum, plasma, DNA, etc). This paper details the organisation of the bank and presents a feasability study concerning 2.000 volunteers.

  16. Mimicking biological functionality with polymers for biomedical applications

    NASA Astrophysics Data System (ADS)

    Green, Jordan J.; Elisseeff, Jennifer H.

    2016-12-01

    The vast opportunities for biomaterials design and functionality enabled by mimicking nature continue to stretch the limits of imagination. As both biological understanding and engineering capabilities develop, more sophisticated biomedical materials can be synthesized that have multifaceted chemical, biological and physical characteristics designed to achieve specific therapeutic goals. Mimicry is being used in the design of polymers for biomedical applications that are required locally in tissues, systemically throughout the body, and at the interface with tissues.

  17. Accommodating ontologies to biological reality--top-level categories of cumulative-constitutively organized material entities.

    PubMed

    Vogt, Lars; Grobe, Peter; Quast, Björn; Bartolomaeus, Thomas

    2012-01-01

    The Basic Formal Ontology (BFO) is a top-level formal foundational ontology for the biomedical domain. It has been developed with the purpose to serve as an ontologically consistent template for top-level categories of application oriented and domain reference ontologies within the Open Biological and Biomedical Ontologies Foundry (OBO). BFO is important for enabling OBO ontologies to facilitate in reliably communicating and managing data and metadata within and across biomedical databases. Following its intended single inheritance policy, BFO's three top-level categories of material entity (i.e. 'object', 'fiat object part', 'object aggregate') must be exhaustive and mutually disjoint. We have shown elsewhere that for accommodating all types of constitutively organized material entities, BFO must be extended by additional categories of material entity. Unfortunately, most biomedical material entities are cumulative-constitutively organized. We show that even the extended BFO does not exhaustively cover cumulative-constitutively organized material entities. We provide examples from biology and everyday life that demonstrate the necessity for 'portion of matter' as another material building block. This implies the necessity for further extending BFO by 'portion of matter' as well as three additional categories that possess portions of matter as aggregate components. These extensions are necessary if the basic assumption that all parts that share the same granularity level exhaustively sum to the whole should also apply to cumulative-constitutively organized material entities. By suggesting a notion of granular representation we provide a way to maintain the single inheritance principle when dealing with cumulative-constitutively organized material entities. We suggest to extend BFO to incorporate additional categories of material entity and to rearrange its top-level material entity taxonomy. With these additions and the notion of granular representation, BFO would

  18. How Discourses of Biology Textbooks Work to Constitute Subjectivity: From the Ethical to the Colonial

    NASA Astrophysics Data System (ADS)

    Bazzul, Jesse

    This thesis examines how discourses of biology textbooks can work to constitute various kinds of subjectivities. Using a Foucauldian archaeological approach to discourse analysis I examine how four Ontario secondary school biology textbooks discursively delimit what can be thought and acted upon, and in the process work to partially constitute students/teachers as sex/gendered; neocolonial; neoliberal (and a subject of work), and ethical subjects and subjectivities. This thesis engages the topic of how discourse can constitute subjectivity in science in three basic ways: First, on a theoretical level, in terms of working out an understanding of subject constitution/interpellation that would also be useful when engaging with other sociopolitical and ethical questions in science education. Secondly, in terms of an empirically based critical discourse analysis that examines how various statements within these four textbooks could set limits on what is possible for students to think and act upon in relation to themselves, science, and the world. Thirdly, this thesis represents a narrative of scholarly development that moves from an engagement of my personal experiences in science education and current science education literature towards the general politico-philosophical topic of subjectivity and biopolitics. This thesis begins with a discussion of my experiences as a science teacher, a review of relevant science education literature, and considerations of subjectivity that relate specifically ii to the specific methodological approach I employ when examining these textbooks. After this I present five chapters, each of which can be thought of as a somewhat separate analysis concerning how the discourses of these textbooks can work to constitute specific subjectivities (each involving different theoretical/methodological considerations). I conclude with a reflection/synthesis chapter and a call to see science education as a site for biopolitical struggle.

  19. Phase biaxiality in nematic liquid crystalline side-chain polymers of various chemical constitutions.

    PubMed

    Severing, Kirsten; Stibal-Fischer, Elke; Hasenhindl, Alfred; Finkelmann, Heino; Saalwächter, Kay

    2006-08-17

    In a previous deuterium NMR study conducted on a liquid crystalline (LC) polymer with laterally attached book-shaped molecules as the mesogenic moiety, we have revealed a biaxial nematic phase below the conventional uniaxial nematic phase (Phys. Rev. Lett. 2004, 92, 125501). To elucidate details of its formation, we here report on deuterium NMR experiments that have been conducted on different types of LC side-chain polymers as well as on mixtures with low-molar-mass mesogens. Different parameters that affect the formation of a biaxial nematic phase, such as the geometry of the attachment, the spacer length between the polymer backbone and the mesogenic unit, as well as the polymer dynamics, were investigated. Surprisingly, also polymers with terminally attached mesogens (end-on polymers) are capable of forming biaxial nematic phases if the flexible spacer is short and thus retains a coupling between the polymer backbone and the LC phase. Furthermore, the most important parameter for the formation of a biaxial nematic phase is the dynamics of the polymer backbone, as the addition of a small percentage of low molar mass LC to the biaxial nematic polymer from the original study served to shift both the glass transition and the appearance of detectable biaxiality in a very similar fashion. Plotting different parameters for the investigated systems as a function of T/Tg also reveals the crucial role of the dynamics of the polymer backbone and hence the glass transition.

  20. Molecularly imprinted polymers for 5-fluorouracil release in biological fluids.

    PubMed

    Puoci, Francesco; Iemma, Francesca; Cirillo, Giuseppe; Picci, Nevio; Matricardi, Pietro; Alhaiqu, Franco

    2007-04-18

    The aim of this work was to investigate the possibility of employing Molecularly Imprinted Polymers (MIPs) as a controlled release device for 5-fluorouracil (5-FU) in biological fluids, especially gastrointestinal ones, compared to Non Imprinted Polymers (NIPs). MIPs were synthesized using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. The capacity of the polymer to recognize and to bind the template selectively in both organic and aqueous media was evaluated. An in vitro release study was performed both in gastrointestinal and in plasma simulating fluids. The imprinted polymers bound much more 5-Fu than the corresponding non-imprinted ones and showed a controlled/sustained drug release, with MIPs release rate being indeed much more sustained than that obtained from NIPs. These polymers represent a potential valid system for drug delivery and this study indicates that the selective binding characteristic of molecularly imprinted polymers is promising for the preparation of novel controlled release drug dosage form.

  1. Bioinspired polymer vesicles and membranes for biological and medical applications.

    PubMed

    Palivan, Cornelia G; Goers, Roland; Najer, Adrian; Zhang, Xiaoyan; Car, Anja; Meier, Wolfgang

    2016-01-21

    Biological membranes play an essential role in living organisms by providing stable and functional compartments, preserving cell architecture, whilst supporting signalling and selective transport that are mediated by a variety of proteins embedded in the membrane. However, mimicking cell membranes - to be applied in artificial systems - is very challenging because of the vast complexity of biological structures. In this respect a highly promising strategy to designing multifunctional hybrid materials/systems is to combine biological molecules with polymer membranes or to design membranes with intrinsic stimuli-responsive properties. Here we present supramolecular polymer assemblies resulting from self-assembly of mostly amphiphilic copolymers either as 3D compartments (polymersomes, PICsomes, peptosomes), or as planar membranes (free-standing films, solid-supported membranes, membrane-mimetic brushes). In a bioinspired strategy, such synthetic assemblies decorated with biomolecules by insertion/encapsulation/attachment, serve for development of multifunctional systems. In addition, when the assemblies are stimuli-responsive, their architecture and properties change in the presence of stimuli, and release a cargo or allow "on demand" a specific in situ reaction. Relevant examples are included for an overview of bioinspired polymer compartments with nanometre sizes and membranes as candidates in applications ranging from drug delivery systems, up to artificial organelles, or active surfaces. Both the advantages of using polymer supramolecular assemblies and their present limitations are included to serve as a basis for future improvements.

  2. Conducting polymer nanostructures for biological applications

    NASA Astrophysics Data System (ADS)

    Berdichevsky, Yevgeny

    A novel polypyrrole nanowire actuator was fabricated and characterized, representing a completely new approach to the design of nanoscale mechanically active components (nanomachines). This design paradigm takes advantage of the fact that unique properties of polypyrrole allow development of mechanically active nanostructures capable of operating in aqueous salt solutions with many potential applications biology and medicine. Template synthesis technique was used to electropolymerize polypyrrole nanowires in the nanoporous alumina templates. Commercial alumina filters were used both "as is" and patterned with microbeads to reduce the open pore density, along with anodized alumina prepared as a thin film on a semiconductor substrate. The ability of the nanowires to expand and contract with applied voltage was then evaluated with scanning electron microscopy and high-resolution optical microscopy. It was confirmed that the nanowires can function as nanoactuators, which is a significant advance in developing nanomechanical structures. Polypyrrole nanoactuators are electrically controlled, rather than relying on changing the chemical composition of solution, can be easily synthesized in parallel and in high numbers without requiring e-beam lithography, and can operate in aqueous salt solutions at biologically-relevant pH. Furthermore, the speed of polypyrrole actuators depends on their size due to diffusion limitations, and nanoactuators are therefore able to operate at higher speeds that micro- or macro-sized devices. The development of these nanoactuators paves the way for mimicking the function of biological actuators such as cilia, creation of controllable membranes, small particle manipulation, cellular nanomechanical probes, and many other biomedical applications. Furthermore, the same technology and process flow used for fabrication of nanoactuators was also used to create nanosensors for detection of electrochemically oxidizable neurotransmitters such as

  3. Polypyrrole-based conducting polymers and interactions with biological tissues

    PubMed Central

    Ateh, D.D; Navsaria, H.A; Vadgama, P

    2006-01-01

    Polypyrrole (PPy) is a conjugated polymer that displays particular electronic properties including conductivity. In biomedical applications, it is usually electrochemically generated with the incorporation of any anionic species including also negatively charged biological macromolecules such as proteins and polysaccharides to give composite materials. In biomedical research, it has mainly been assessed for its role as a reporting interface in biosensors. However, there is an increasing literature on the application of PPy as a potentially electrically addressable tissue/cell support substrate. Here, we review studies that have considered such PPy based conducting polymers in direct contact with biological tissues and conclude that due to its versatile functional properties, it could contribute to a new generation of biomaterials. PMID:17015302

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

    PubMed

    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).

  5. Polymer application for separation/filtration of biological active compounds

    NASA Astrophysics Data System (ADS)

    Tylkowski, B.; Tsibranska, I.

    2017-06-01

    Membrane technology is an important part of the engineer's toolbox. This is especially true for industries that process food and other products with their primary source from nature. This review is focused on ongoing development work using membrane technologies for concentration and separation of biologically active compounds, such as polyphenols and flavonoids. We provide the readers not only with the last results achieve in this field but also, we deliver detailed information about the membrane types and polymers used for their preparation.

  6. Accommodating Ontologies to Biological Reality—Top-Level Categories of Cumulative-Constitutively Organized Material Entities

    PubMed Central

    Vogt, Lars; Grobe, Peter; Quast, Björn; Bartolomaeus, Thomas

    2012-01-01

    Background The Basic Formal Ontology (BFO) is a top-level formal foundational ontology for the biomedical domain. It has been developed with the purpose to serve as an ontologically consistent template for top-level categories of application oriented and domain reference ontologies within the Open Biological and Biomedical Ontologies Foundry (OBO). BFO is important for enabling OBO ontologies to facilitate in reliably communicating and managing data and metadata within and across biomedical databases. Following its intended single inheritance policy, BFO's three top-level categories of material entity (i.e. ‘object’, ‘fiat object part’, ‘object aggregate’) must be exhaustive and mutually disjoint. We have shown elsewhere that for accommodating all types of constitutively organized material entities, BFO must be extended by additional categories of material entity. Methodology/Principal Findings Unfortunately, most biomedical material entities are cumulative-constitutively organized. We show that even the extended BFO does not exhaustively cover cumulative-constitutively organized material entities. We provide examples from biology and everyday life that demonstrate the necessity for ‘portion of matter’ as another material building block. This implies the necessity for further extending BFO by ‘portion of matter’ as well as three additional categories that possess portions of matter as aggregate components. These extensions are necessary if the basic assumption that all parts that share the same granularity level exhaustively sum to the whole should also apply to cumulative-constitutively organized material entities. By suggesting a notion of granular representation we provide a way to maintain the single inheritance principle when dealing with cumulative-constitutively organized material entities. Conclusions/Significance We suggest to extend BFO to incorporate additional categories of material entity and to rearrange its top-level material

  7. Logarithmic rate based elasto-viscoplastic cyclic constitutive model for soft biological tissues.

    PubMed

    Zhu, Yilin; Kang, Guozheng; Yu, Chao; Poh, Leong Hien

    2016-08-01

    Based on the logarithmic rate and piecewise linearization theory, a thermodynamically consistent elasto-viscoplastic constitutive model is developed in the framework of finite deformations to describe the nonlinear time-dependent biomechanical performances of soft biological tissues, such as nonlinear anisotropic monotonic stress-strain responses, stress relaxation, creep and ratchetting. In the proposed model, the soft biological tissue is assumed as a typical composites consisting of an isotropic matrix and anisotropic fiber aggregation. Accordingly, the free energy function and stress tensor are divided into two parts related to the matrix and fiber aggregation, respectively. The nonlinear biomechanical responses of the tissues are described by the piecewise linearization theory with hypo-elastic relations of fiber aggregation. The evolution equations of viscoplasticity are formulated from the dissipation inequalities by the co-directionality hypotheses. The anisotropy is considered in the hypo-elastic relations and viscoplastic flow rules by introducing some material parameters dependent on the loading direction. Then the capability of the proposed model to describe the nonlinear time-dependent deformation of soft biological tissues is verified by comparing the predictions with the corresponding experimental results of three tissues. It is seen that the predicted monotonic stress-strain responses, stress relaxation, creep and ratchetting of soft biological tissues are in good agreement with the corresponding experimental ones. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. The effect of heat developed during high strain rate deformation on the constitutive modeling of amorphous polymers

    NASA Astrophysics Data System (ADS)

    Safari, Keivan H.; Zamani, Jamal; Guedes, Rui M.; Ferreira, Fernando J.

    2016-02-01

    An adiabatic constitutive model is proposed for large strain deformation of polycarbonate (PC) at high strain rates. When the strain rate is sufficiently high such that the heat generated does not have time to transfer to the surroundings, temperature of material rises. The high strain rate deformation behavior of polymers is significantly affected by temperature-dependent constants and thermal softening. Based on the isothermal model which first was introduced by Mulliken and Boyce et al. (Int. J. Solids Struct. 43:1331-1356, 2006), an adiabatic model is proposed to predict the yield and post-yield behavior of glassy polymers at high strain rates. When calculating the heat generated and the temperature changes during the step by step simulation of the deformation, temperature-dependent elastic constants are incorporated to the constitutive equations. Moreover, better prediction of softening phenomena is achieved by the new definition for softening parameters of the proposed model. The constitutive model has been implemented numerically into a commercial finite element code through a user material subroutine (VUMAT). The experimental results, obtained using a split Hopkinson pressure bar, are supported by dynamic mechanical thermal analysis (DMTA) and Decompose/Shift/Reconstruct (DSR) method. Comparison of adiabatic model predictions with experimental data demonstrates the ability of the model to capture the characteristic features of stress-strain curve of the material at very high strain rates.

  9. Coordination polymer gels with important environmental and biological applications.

    PubMed

    Jung, Jong Hwa; Lee, Ji Ha; Silverman, Julian R; John, George

    2013-02-07

    Coordination Polymer Gels (CPGs) constitute a subset of solid-like metal ion and bridging organic ligand structures (similar to metal-organic frameworks) that form multi-dimensional networks through a trapped solvent as a result of non-covalent interactions. While physical properties of these gels are similar to conventional high molecular weight organic polymer gels, coordination polymer gel systems are often fully reversible and can be assembled and disassembled in the presence of additional energy (heat, sonication, shaking) to give a solution of solvated gelators. Compared to gels resulting from purely organic self-assembled low molecular weight gelators, metal ions incorporated into the fibrilar networks spanning the bulk solvent can impart CPGs with added functionalities. The solid/liquid nature of the gels allows for species to migrate through the gel system and interact with metals, ligands, and the solvent. Chemosensing, catalysis, fluorescence, and drug-delivery applications are some of the many potential uses for these dynamic systems, taking advantage of the metal ion's coordination, the organic polydentate ligand's orientation and functionality, or a combination of these properties. By fine tuning these systems through metal ion and ligand selection and by directing self-assembly with external stimuli the rational synthesis of practical systems can be envisaged.

  10. Heparin-Mimicking Polymers: Synthesis and Biological Applications.

    PubMed

    Paluck, Samantha J; Nguyen, Thi H; Maynard, Heather D

    2016-11-14

    Heparin is a naturally occurring, highly sulfated polysaccharide that plays a critical role in a range of different biological processes. Therapeutically, it is mostly commonly used as an injectable solution as an anticoagulant for a variety of indications, although it has also been employed in other forms such as coatings on various biomedical devices. Due to the diverse functions of this polysaccharide in the body, including anticoagulation, tissue regeneration, anti-inflammation, and protein stabilization, and drawbacks of its use, analogous heparin-mimicking materials are also widely studied for therapeutic applications. This review focuses on one type of these materials, namely, synthetic heparin-mimicking polymers. Utilization of these polymers provides significant benefits compared to heparin, including enhancing therapeutic efficacy and reducing side effects as a result of fine-tuning heparin-binding motifs and other molecular characteristics. The major types of the various polymers are summarized, as well as their applications. Because development of a broader range of heparin-mimicking materials would further expand the impact of these polymers in the treatment of various diseases, future directions are also discussed.

  11. Heparin-Mimicking Polymers: Synthesis and Biological Applications

    PubMed Central

    2016-01-01

    Heparin is a naturally occurring, highly sulfated polysaccharide that plays a critical role in a range of different biological processes. Therapeutically, it is mostly commonly used as an injectable solution as an anticoagulant for a variety of indications, although it has also been employed in other forms such as coatings on various biomedical devices. Due to the diverse functions of this polysaccharide in the body, including anticoagulation, tissue regeneration, anti-inflammation, and protein stabilization, and drawbacks of its use, analogous heparin-mimicking materials are also widely studied for therapeutic applications. This review focuses on one type of these materials, namely, synthetic heparin-mimicking polymers. Utilization of these polymers provides significant benefits compared to heparin, including enhancing therapeutic efficacy and reducing side effects as a result of fine-tuning heparin-binding motifs and other molecular characteristics. The major types of the various polymers are summarized, as well as their applications. Because development of a broader range of heparin-mimicking materials would further expand the impact of these polymers in the treatment of various diseases, future directions are also discussed. PMID:27739666

  12. Peptidomimetic Star Polymers for Targeting Biological Ion Channels

    PubMed Central

    Chen, Rong; Lu, Derong; Xie, Zili; Feng, Jing; Jia, Zhongfan; Ho, Junming; Coote, Michelle L.; Wu, Yingliang; Monteiro, Michael J.; Chung, Shin-Ho

    2016-01-01

    Four end-functionalized star polymers that could attenuate the flow of ionic currents across biological ion channels were first de novo designed computationally, then synthesized and tested experimentally on mammalian K+ channels. The 4-arm ethylene glycol conjugate star polymers with lysine or a tripeptide attached to the end of each arm were specifically designed to mimic the action of scorpion toxins on K+ channels. Molecular dynamics simulations showed that the lysine side chain of the polymers physically occludes the pore of Kv1.3, a target for immuno-suppression therapy. Two of the compounds tested were potent inhibitors of Kv1.3. The dissociation constants of these two compounds were computed to be 0.1 μM and 0.7 μM, respectively, within 3-fold to the values derived from subsequent experiments. These results demonstrate the power of computational methods in molecular design and the potential of star polymers as a new infinitely modifiable platform for ion channel drug discovery. PMID:27007701

  13. 3D Printing Polymers with Supramolecular Functionality for Biological Applications.

    PubMed

    Pekkanen, Allison M; Mondschein, Ryan J; Williams, Christopher B; Long, Timothy E

    2017-09-11

    Supramolecular chemistry continues to experience widespread growth, as fine-tuned chemical structures lead to well-defined bulk materials. Previous literature described the roles of hydrogen bonding, ionic aggregation, guest/host interactions, and π-π stacking to tune mechanical, viscoelastic, and processing performance. The versatility of reversible interactions enables the more facile manufacturing of molded parts with tailored hierarchical structures such as tissue engineered scaffolds for biological applications. Recently, supramolecular polymers and additive manufacturing processes merged to provide parts with control of the molecular, macromolecular, and feature length scales. Additive manufacturing, or 3D printing, generates customizable constructs desirable for many applications, and the introduction of supramolecular interactions will potentially increase production speed, offer a tunable surface structure for controlling cell/scaffold interactions, and impart desired mechanical properties through reinforcing interlayer adhesion and introducing gradients or self-assembled structures. This review details the synthesis and characterization of supramolecular polymers suitable for additive manufacture and biomedical applications as well as the use of supramolecular polymers in additive manufacturing for drug delivery and complex tissue scaffold formation. The effect of supramolecular assembly and its dynamic behavior offers potential for controlling the anisotropy of the printed objects with exquisite geometrical control. The potential for supramolecular polymers to generate well-defined parts, hierarchical structures, and scaffolds with gradient properties/tuned surfaces provides an avenue for developing next-generation biomedical devices and tissue scaffolds.

  14. Solid-State Constitutive Modelling of Glassy Polymers: Coupling the Rolie-Poly Equations for Melts with Anisotropic Viscoplastic Flow

    NASA Astrophysics Data System (ADS)

    De Focatiis, Davide S. A.; Embery, John; Buckley, C. Paul

    2008-07-01

    This paper investigates the behaviour of a well-characterised monodisperse grade of entangled atactic polystyrene across a very wide temperature and strain rate range through linear and non-linear melt rheology and solid-state deformation. In an effort to construct a constitutive model for large deformations able to describe rheological response right across this wide timescale, two well-established rheological models are combined: the well known RoliePoly (RP) conformational melt model and the Oxford glass-rubber constitutive model for glassy polymers. Comparisons between experimental data and simulations from a numerical implementation of the model illustrate that the model can cope well with the range of deformations in which orientation is limited to length-scales longer than an entanglement length. One approach in which the model can be expanded to incorporate the effects of orientation on shorter length scales using anisotropic viscoplastic flow is briefly discussed.

  15. Solid-State Constitutive Modelling of Glassy Polymers: Coupling the Rolie-Poly Equations for Melts with Anisotropic Viscoplastic Flow

    SciTech Connect

    De Focatiis, Davide S. A.; Buckley, C. Paul; Embery, John

    2008-07-07

    This paper investigates the behaviour of a well-characterised monodisperse grade of entangled atactic polystyrene across a very wide temperature and strain rate range through linear and non-linear melt rheology and solid-state deformation. In an effort to construct a constitutive model for large deformations able to describe rheological response right across this wide timescale, two well-established rheological models are combined: the well known RoliePoly (RP) conformational melt model and the Oxford glass-rubber constitutive model for glassy polymers. Comparisons between experimental data and simulations from a numerical implementation of the model illustrate that the model can cope well with the range of deformations in which orientation is limited to length-scales longer than an entanglement length. One approach in which the model can be expanded to incorporate the effects of orientation on shorter length scales using anisotropic viscoplastic flow is briefly discussed.

  16. Silica passivated conjugated polymer nanoparticles for biological imaging applications

    NASA Astrophysics Data System (ADS)

    Bourke, Struan; Urbano, Laura; Olona, Antoni; Valderrama, Ferran; Dailey, Lea Ann; Green, Mark A.

    2017-02-01

    Colorectal and prostate cancers are major causes of cancer-related death, with early detection key to increased survival. However, as symptoms occur during advanced stages and current diagnostic methods have limitations, there is a need for new fluorescent probes that remain bright, are biocompatible and can be targeted. Conjugated polymer nanoparticles have shown great promise in biological imaging due to their unique optical properties. We have synthesised small, bright, photo-stable CN-PPV, nanoparticles encapsulated with poloxamer polymer and a thin silica shell. By incubating the CN-PPV silica shelled cross-linked (SSCL) nanoparticles in mammalian (HeLa) cells; we were able to show that cellular uptake occurred. Uptake was also shown by incubating the nanoparticles in RWPE-1, WPE1-NB26 and WPE1- NA22 prostate cancer cell lines. Finally, HEK cells were used to show the particles had limited cytotoxicity.

  17. Combined Mechanical and Electrical Study of Polymers of Biological Origin

    NASA Astrophysics Data System (ADS)

    Zsoldos, G.; Szoda, K.; Marossy, K.

    2017-02-01

    Thermally Simulated Depolarization Current measurement is an excellent but not widely used method for identifying relaxation processes in polymers. The DMA method is used here to analyze the mechanical changes depend on temperature in biopolymers. The two techniques take advantage of the energy changes involved in the various phase transitions of certain polymer molecules. This allows for several properties of the material to be ascertained; melting points, enthalpies of melting, crystallization temperatures, glass transition temperatures and degradation temperatures. The examined biopolymer films are made from biological materials such as proteins and polysaccharides. These materials have gained wide usage in pharmaceutical, medical and food areas. The uses of biopolymer films depend on their structure and mechanical properties. This work is based on pectin and gelatin films. The films were prepared by casting. The casting technique used aqueous solutions in each case of sample preparation. The manufacturing process of the pectin and gelatin films was a single stage solving process.

  18. Stochastic hyperelastic constitutive laws and identification procedure for soft biological tissues with intrinsic variability.

    PubMed

    Staber, B; Guilleminot, J

    2017-01-01

    In this work, we address the constitutive modeling, in a probabilistic framework, of the hyperelastic response of soft biological tissues. The aim is on the one hand to mimic the mean behavior and variability that are typically encountered in the experimental characterization of such materials, and on the other hand to derive mathematical models that are almost surely consistent with the theory of nonlinear elasticity. Towards this goal, we invoke information theory and discuss a stochastic model relying on a low-dimensional parametrization. We subsequently propose a two-step methodology allowing for the calibration of the model using standard data, such as mean and standard deviation values along a given loading path. The framework is finally applied and benchmarked on three experimental databases proposed elsewhere in the literature. It is shown that the stochastic model allows experiments to be accurately reproduced, regardless of the tissue under consideration.

  19. Low power, biologically benign NIR light triggers polymer disassembly

    PubMed Central

    Fomina, Nadezda; McFearin, Cathryn L.; Sermsakdi, Marleen; Morachis, José M.; Almutairi, Adah

    2011-01-01

    Near infrared (NIR) irradiation can penetrate up to 10 cm deep into tissues and be remotely applied with high spatial and temporal precision. Despite its potential for various medical and biological applications, there is a dearth of biomaterials that are responsive at this wavelength region. Herein we report a polymeric material that is able to disassemble in response to biologically benign levels of NIR irradiation upon two-photon absorption. The design relies on the photolysis of the multiple pendant 4-bromo7-hydroxycoumarin protecting groups to trigger a cascade of cyclization and rearrangement reactions leading to the degradation of the polymer backbone. The new material undergoes a 50% Mw loss after 25 sec of ultraviolet (UV) irradiation by single photon absorption and 21 min of NIR irradiation via two-photon absorption. Most importantly, even NIR irradiation at biologically benign laser power is sufficient to cause significant polymer disassembly. Furthermore, this material is well tolerated by cells both before and after degradation. These results demonstrate for the first time a NIR sensitive material with potential to be used for in vivo applications. PMID:22096258

  20. pH-responsive fluorescence chemical sensor constituted by conjugated polymers containing pyridine rings.

    PubMed

    Adachi, Naoya; Kaneko, Yuki; Sekiguchi, Kazuki; Sugiyama, Hiroki; Sugeno, Masafumi

    2015-12-01

    Poly(p-pyridinium phenylene ethynylene)s (PPyPE) functionalized with alternating donor-acceptor repeat units were synthesized by a Pd-catalyzed Sonogashira coupling reaction between diethynyl monomer and di-iodopyridine for use as a pH-responsive fluorescence chemical sensor. The synthesized PPyPE, containing pyridine units, was characterized by FT-IR, (1)H and (13)C NMR, UV-visible and fluorescence spectroscopies. We investigated the relationship between changes of optical properties and protonation/deprotonation of PPyPE containing pyridine units in solution. Addition of HCl decreased and red-shifted the fluorescence intensity of the conjugated polymers that contained pyridine rings; fluorescence intensity of the polymers increased upon addition of NaOH solution. The synthesized PPyPE was found to be an effective and reusable chemical sensor for pH sensing.

  1. Constitutive modeling of large inelastic deformation of amorphous polymers: Free volume and shear transformation zone dynamics

    NASA Astrophysics Data System (ADS)

    Voyiadjis, George Z.; Samadi-Dooki, Aref

    2016-06-01

    Due to the lack of the long-range order in their molecular structure, amorphous polymers possess a considerable free volume content in their inter-molecular space. During finite deformation, these free volume holes serve as the potential sites for localized permanent plastic deformation inclusions which are called shear transformation zones (STZs). While the free volume content has been experimentally shown to increase during the course of plastic straining in glassy polymers, thermal analysis of stored energy due to the deformation shows that the STZ nucleation energy decreases at large plastic strains. The evolution of the free volume, and the STZs number density and nucleation energy during the finite straining are formulated in this paper in order to investigate the uniaxial post-yield softening-hardening behavior of the glassy polymers. This study shows that the reduction of the STZ nucleation energy, which is correlated with the free volume increase, brings about the post-yield primary softening of the amorphous polymers up to the steady-state strain value; and the secondary hardening is a result of the increased number density of the STZs, which is required for large plastic strains, while their nucleation energy is stabilized beyond the steady-state strain. The evolutions of the free volume content and STZ nucleation energy are also used to demonstrate the effect of the strain rate, temperature, and thermal history of the sample on its post-yield behavior. The obtained results from the model are compared with the experimental observations on poly(methyl methacrylate) which show a satisfactory consonance.

  2. Antimicrobial potential of consolidation polymers loaded with biological copper nanoparticles.

    PubMed

    Essa, Ashraf M M; Khallaf, Mohamed K

    2016-07-11

    Biodeterioration of historic monuments and stone works by microorganisms takes place as a result of biofilm production and secretion of organic compounds that negatively affect on the stone matrix. Copper nanoparticles (CuNPs) were prepared biologically using the headspace gases generated by the bacterial culture Escherichia coli Z1. The antimicrobial activity of CuNPs was evaluated against the bacterial strains Bacillus subtilis, Micrococcus luteus, Streptomyces parvulus, Escherichia coli, Pseudomonas aeruginosa as well as some fungal strains Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Fusarium solani and Alternaria solani. Biological CuNPs demonstrated antibacterial and antifungal activities higher than those of the untreated copper sulfate. At the same time, limestone and sandstone blocks treated with consolidation polymers functionalized with CuNPs recorded apparent antimicrobial activity against E. coli, S. parvulus and B. subtilis in addition to an improvement in the physical and mechanical characters of the treated stones. Furthermore, the elemental composition of CuNPs was elucidated using electron dispersive x-ray system connected with the scanning electron microscope. Consolidation polymers impregnated with CuNPs could be used to restrain microbial deterioration in addition to the refinement of physico-mechanical behavior of the historic stones.

  3. Polymer biomaterial constructs for regenerative medicine and functional biological systems

    NASA Astrophysics Data System (ADS)

    Meng, Linghui

    The use of collagen as a biomaterial is currently undergoing a renaissance in the tissue engineering field. The excellent biocompatibility and safety due to its biological characteristics, such as biodegradability and weak antigenicity, make collagen a primary material resource in medical applications. Described herein is work towards the development of novel collagen-based matrices, with additional multi-functionality imparted through a novel in-situ crosslinking approach. The process of electrospinning has become a widely used technique for the creation of fibrous scaffolds for tissue engineering applications due to its ability to rapidly create structures composed of nano-scale polymer fibers closely resembling the architecture of the extracellular matrix (ECM). Collagen-PCL sheath-core bicomponent fibrous scaffolds were fabricated using a novel variation on traditional electrospinning, known as co-axial electrospinning. The results showed that the addition of a synthetic polymer core into collagen nanofibers remarkably increased the mechanical strength of collagen matrices spun from the benign solvent system. A novel single-step, in-situ collagen crosslink approach was developed in order to solve the problems dominating traditional collagen crosslinking methods, such as dimensional shrinking and loss of porous morphology, and to simplify the crosslinking procedure for electrospun collagen scaffolds. The excess amount of NHS present in the crosslinking mixture was found to delay the EDC/collagen coupling reaction in a controlled fashion. Fundamental investigations into the development and characterization of in-situ crosslinked collagen matrices such as fibrous scaffolds, gels and sponges, as well as their biomedical applications including cell culture substrates, wound dressings, drug delivery matrices and bone regeneration substitutes, were performed. The preliminary mice studies indicated that the in-situ crosslinked collagen matrices could be good candidates

  4. Light emitting conjugated polymers for use in biological detection platforms

    NASA Astrophysics Data System (ADS)

    Gaylord, Brent S.

    Recent interest in conjugated polymers has grown from their demonstrated utility in various "plastic" and/or "molecular" electronic applications to include organic light emitting diodes (OLED's), thin film transistors and photovoltaics. Due to their intrinsically delocalized electronic structure, these same materials show enormous potential as highly responsive optical reporters for chemical and biological interactions. Inter- and intra-chain energy migration, coupled with the formation of strong electrostatic complexes between opposite charged acceptors, allows for extraordinary modulation of their fluorescent response. When these properties are correlated with a specific biological recognition event, the result is a biosensor with optically enhanced or amplified performance. Such features are highly desirable in detection schemes where the target analyte is in limited supply, as is most often the case. Within these studies we demonstrate how variations in test media composition (i.e. surfactant, buffers, proteins, DNA, etc.) and molecular structure influence those photophysical properties of conjugated polymers related to biosensor design. To this end, both anionic polyphenylenevinylene (PPV) and cationic polyfluorene-cophenylene structures were examined. Model oligomer structures were employed throughout the study for delineating structure-property relationships, as such detailed correlation is inherently more difficult for the less defined polymeric structures (i.e. polydispersity, batch-to-batch variation, purity, etc.). Studies using light scattering and optical spectroscopy highlight the extensive aggregation of these fluorescent, amphiphilic polyelectrolytes in aqueous solution. Variations in chromophore size, charge and concentration provide interesting comparisons in quenching and/or energy transfer processes, as well as, in their interactions with biological molecules. Ultimately, this information was utilized to develop a novel platform for highly

  5. Formulation and biological evaluation of glimepiride-cyclodextrin-polymer systems.

    PubMed

    Ammar, H O; Salama, H A; Ghorab, M; Mahmoud, A A

    2006-02-17

    Glimepiride is one of the third generation sulfonylureas used for treatment of type 2 diabetes. Poor aqueous solubility and slow dissolution rate of the drug lead to irreproducible clinical response or therapeutic failure in some cases due to subtherapeutic plasma drug levels. Consequently, the rationale of this study was to improve the biological performance of this drug through enhancing its solubility and dissolution rate. Inclusion complexes of glimepiride in beta-cyclodextrin (beta-CyD), hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and sulfobutylether-beta-cyclodextrin (SBE-beta-CyD), with or without water soluble polymers were prepared by the kneading method. Binary systems were characterized by thermogravimetric analysis, IR spectroscopy and X-ray diffractometry. Phase solubility diagrams revealed increase in solubility of the drug upon cyclodextrin addition, showing A(p) type plot indicating high order complexation. All the ternary systems containing beta-CyD or HP-beta-CyD showed higher dissolution efficiency compared to the corresponding binary systems. The hypoglycemic effect of the most rapidly dissolving ternary system of glimepiride-HP-beta-CyD-PEG 4000 was evaluated after oral administration in diabetic rats by measuring blood glucose levels. The results indicated that this ternary system improves significantly the therapeutic efficacy of the drug. In conclusion, the association of water soluble polymers with glimepiride-CyD systems leads to great enhancement in dissolution rate, increased duration of action and improvement of therapeutic efficacy of the drug.

  6. The Significance of Incorporating Nanoscale Fluctuations in a Constitutive Description of Glassy Polymers

    NASA Astrophysics Data System (ADS)

    Caruthers, James

    2015-03-01

    The current picture of the glass involves dynamic heterogeneity, where nanoscopic regions of the glass have order-of-magnitude differences in local mobility that evolve with time. Dynamic heterogeneity provides a critical challenge to the traditional nonlinear continuum models, where both temporal and spatial fluctuations are averaged as a result of the continuum postulate. In order to acknowledge dynamic heterogeneity, a Stochastic Constitutive Model (SCM) has been developed to describe the nonlinear viscoelastic behavior of polymeric glasses, where (i) temporal fluctuations are explicitly included and (ii) the local mobility depends upon the local state of the material (e.g. local stress and local entropy) vs. traditional viscoelastic/viscoelastic models where macroscopic mobility depends upon the macroscopic state. The SCM is able to describe a number of nonlinear relaxation phenomena that cannot be predicted by traditional nonlinear viscoelastic/viscoplastic models, including (i) post-yield stress softening and its dependence on annealing time, (ii) the inversion of the strain dependence of nonlinear stress relaxation with the loading rate, (iii) stress memory and (iv) tertiary creep and creep-recovery. This paper will argue that incorporation of nanoscopic fluctuations is a necessary component for a description of the thermomechanical behavior of polymeric glasses. Support from NSF Grant 1363326-CMMI.

  7. Assembled core-shell nanostructures of gold nanoparticles with biocompatible polymers toward biology.

    PubMed

    Li, Dongxiang; Li, Qianru; Hao, Xiongwen; Zhang, Yaojun; Zhang, Zhupeng; Li, Chunfang

    2014-03-01

    The present review focuses on core-shell nanostructures of spherical gold nanoparticles (Au NPs) and biocompatible polymers mainly from the view points of preparation approaches, nanocomposite properties and potential applications for biology. The preparation approaches are assorted into direct-reduction, covalent "graft-to", "graft-from" approach, surface bonding and physical adsorption. Various biocompatible polymers are involved such as the thermosensitive polymers, pH-responsive polymers, antibiofouling polymers, conductive polymers and several natural polymers. The encapsulating and loading properties, cellular uptake and drug release control, as well as biorecognition, targeting and sensing potential are discussed in connection with biological systems. These polymeric gold nanocomposites will have a great potential in biotechnology and life science but also face enormous challenge in future applications.

  8. Combinatorial synthesis and screening of non-biological polymers

    DOEpatents

    Schultz, Peter G.; Xiang, Xiao-Dong; Goldwasser, Isy; Briceno, Gabriel; Sun, Xiao-Dong; Wang, Kai-An

    2006-04-25

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  9. Research Programs Constituting U.S. Participation in the International Biological Program.

    ERIC Educational Resources Information Center

    National Academy of Sciences--National Research Council, Washington, DC. Div. of Biology and Agriculture.

    The United States contribution to the International Biological Program, which aims to understand more clearly the interrelationships within ecosystems, is centered on multidisciplinary research programs investigating the biological basis of ecological productivity and human welfare. Integrated research programs have been established for the…

  10. Constitutive gene expression and specification of tissue identity in adult planarian biology

    PubMed Central

    Reddien, Peter W.

    2011-01-01

    Planarians are flatworms that constitutively maintain adult tissues through cell turnover and can regenerate entire organisms from tiny body fragments. In addition to requiring new cells (from neoblasts), these feats require mechanisms that specify tissue identity in the adult. Critical roles for Wnt and BMP signaling in regeneration and maintenance of the body axes have been uncovered, among other regulatory factors. Available data indicate that genes involved in positional identity regulation at key embryonic stages in other animals display persisting regionalized expression in adult planarians. These expression patterns suggest that a constitutively active gene expression map exists for maintenance of the planarian body. Planarians therefore present a fertile ground for identification of factors regulating regionalization of the metazoan body plan and for study of the attributes of these factors that can lead to maintenance and regeneration of adult tissues. PMID:21680047

  11. Biologic significance of constitutive and subliminal growth factor production by bone marrow stroma.

    PubMed

    Kittler, E L; McGrath, H; Temeles, D; Crittenden, R B; Kister, V K; Quesenberry, P J

    1992-06-15

    The "stromal" or adherent cells of long-term murine Dexter explant bone marrow cultures provide the best in vitro model of the bone marrow microenvironment. Colony-stimulating factor-1 (CSF-1) is produced constitutively by these cells and is easily detected, but most investigators have not found constitutive production of the other hemolymphopoietic cytokines. We have previously reported the detection of granulocyte-macrophage-CSF (GM-CSF) in murine stromal cultures and its induction by the lectin Pokeweed mitogen. The present studies analyzing stromal cytokine messenger RNA (mRNA) production by standard Northern blot analysis show constitutive production of mRNAs for CSF-1, GM-CSF, granulocyte-CSF (G-CSF), c-kit ligand (KL), and interleukin-6 (IL-6), but not IL-3, IL-4, or IL-5 by 3-week irradiated or nonirradiated murine Dexter stromal cells. Exposure of stromal cells to Pokeweed mitogen or IL-1 16 hours before RNA harvest induces the messages for GM-CSF, G-CSF, KL, and IL-6, but not IL-3, IL-4, IL-5, or CSF-1. Polymerase chain reaction amplification of cDNA made with reverse transcriptase from stromal RNA using two separate sets of IL-3-specific primers shows the presence of IL-3 message in irradiated stromal cells, which is only detectable with this more sensitive technique. The factor-dependent cell lines FDC-P1 and 32D are supported by the stromal cells without the addition of exogenous growth factors, demonstrating a cytokine activity in these cultures that is inhibited by the addition of anti-IL-3 or anti-GM-CSF antibodies. These data indicate that murine Dexter stromal cells constitutively produce CSF-1, GM-CSF, G-CSF, IL-6, KL, and IL-3. This growth factor production could explain the support of granulocyte, macrophage, and megakaryocyte production and stem cell maintenance in Dexter-type long-term murine bone marrow cultures.

  12. Nanoengineered Templated Polymer Particles: Navigating the Biological Realm.

    PubMed

    Cui, Jiwei; Richardson, Joseph J; Björnmalm, Mattias; Faria, Matthew; Caruso, Frank

    2016-06-21

    Nanoengineered materials offer tremendous promise for developing the next generation of therapeutics. We are transitioning from simple research questions, such as "can this particle eradicate cancer cells?" to more sophisticated ones like "can we design a particle to preferentially deliver cargo to a specific cancer cell type?" These developments are poised to usher in a new era of nanoengineered drug delivery systems. We primarily work with templating methods for engineering polymer particles and investigate their biological interactions. Templates are scaffolds that facilitate the formation of particles with well-controlled size, shape, structure, stiffness, stability, and surface chemistry. In the past decade, breakthroughs in engineering new templates, combined with advances in coating techniques, including layer-by-layer (LbL) assembly, surface polymerization, and metal-phenolic network (MPN) coordination chemistry, have enabled particles with specific physicochemical properties to be engineered. While materials science offers an ever-growing number of new synthesis techniques, a central challenge of therapeutic delivery has become understanding how nanoengineered materials interact with biological systems. Increased collaboration between chemists, biologists, and clinicians has resulted in a vast research output on bio-nano interactions. Our understanding of cell-particle interactions has grown considerably, but conventional in vitro experimentation provides limited information, and understanding how to bridge the in vitro/in vivo gap is a continuing challenge. As has been demonstrated in other fields, there is now a growing interest in applying computational approaches to advance this area. A considerable knowledge base is now emerging, and with it comes new and exciting opportunities that are already being capitalized on through the translation of materials into the clinic. In this Account, we outline our perspectives gained from a decade of work at the

  13. The constitutional protection of trade secrets and patents under the Biologics Price Competition and Innovation Act of 2009.

    PubMed

    Epstein, Richard A

    2011-01-01

    The Biologics Price Competition and Innovation Act of 2009 ("Biosimilars Act") is for the field of pharmaceutical products the single most important legislative development since passage of the Drug Price Competition and Patent Term Restoration Act of 1984 ("Hatch-Waxman Act"), on which portions of the Biosimilars Act are clearly patterned. Congress revised section 351 of the Public Health Service Act (PHSA) to create a pathway for FDA approval of "biosimilar" biological products. Each biosimilar applicant is required to cite in its application a "reference product" that was approved on the basis of a full application containing testing data and manufacturing information, which is owned and was submitted by another company and much of which constitutes trade secret information subject to constitutional protection. Because the Biosimilars Act authorizes biosimilar applicants to cite these previously approved applications, the implementation of the new legislative scheme raises critical issues under the Fifth Amendment of the Constitution, pursuant to which private property--trade secrets included--may not be taken for public use, without "just compensation." FDA must confront those issues as it implements the scheme set out in the Biosimilars Act. This article will discuss these issues, after providing a brief overview of the Biosimilars Act and a more detailed examination of the law of trade secrets.

  14. Constitutive expression of tdTomato protein as a cytotoxicity and proliferation marker for space radiation biology.

    PubMed

    Chishti, Arif A; Hellweg, Christine E; Berger, Thomas; Baumstark-Khan, Christa; Feles, Sebastian; Kätzel, Thorben; Reitz, Günther

    2015-01-01

    The radiation risk assessment for long-term space missions requires knowledge on the biological effectiveness of different space radiation components, e.g. heavy ions, on the interaction of radiation and other space environmental factors such as microgravity, and on the physical and biological dose distribution in the human body. Space experiments and ground-based experiments at heavy ion accelerators require fast and reliable test systems with an easy readout for different endpoints. In order to determine the effect of different radiation qualities on cellular proliferation and the biological depth dose distribution after heavy ion exposure, a stable human cell line expressing a novel fluorescent protein was established and characterized. tdTomato, a red fluorescent protein of the new generation with fast maturation and high fluorescence intensity, was selected as reporter of cell proliferation. Human embryonic kidney (HEK/293) cells were stably transfected with a plasmid encoding tdTomato under the control of the constitutively active cytomegalovirus (CMV) promoter (ptdTomato-N1). The stably transfected cell line was named HEK-ptdTomato-N1 8. This cytotoxicity biosensor was tested by ionizing radiation (X-rays and accelerated heavy ions) exposure. As biological endpoints, the proliferation kinetics and the cell density reached 100 h after irradiation reflected by constitutive expression of the tdTomato were investigated. Both were reduced dose-dependently after radiation exposure. Finally, the cell line was used for biological weighting of heavy ions of different linear energy transfer (LET) as space-relevant radiation quality. The relative biological effectiveness of accelerated heavy ions in reducing cellular proliferation peaked at an LET of 91 keV/μm. The results of this study demonstrate that the HEK-ptdTomato-N1 reporter cell line can be used as a fast and reliable biosensor system for detection of cytotoxic damage caused by ionizing radiation. Copyright

  15. Constitutive expression of tdTomato protein as a cytotoxicity and proliferation marker for space radiation biology

    NASA Astrophysics Data System (ADS)

    Chishti, Arif A.; Hellweg, Christine E.; Berger, Thomas; Baumstark-Khan, Christa; Feles, Sebastian; Kätzel, Thorben; Reitz, Günther

    2015-01-01

    The radiation risk assessment for long-term space missions requires knowledge on the biological effectiveness of different space radiation components, e.g. heavy ions, on the interaction of radiation and other space environmental factors such as microgravity, and on the physical and biological dose distribution in the human body. Space experiments and ground-based experiments at heavy ion accelerators require fast and reliable test systems with an easy readout for different endpoints. In order to determine the effect of different radiation qualities on cellular proliferation and the biological depth dose distribution after heavy ion exposure, a stable human cell line expressing a novel fluorescent protein was established and characterized. tdTomato, a red fluorescent protein of the new generation with fast maturation and high fluorescence intensity, was selected as reporter of cell proliferation. Human embryonic kidney (HEK/293) cells were stably transfected with a plasmid encoding tdTomato under the control of the constitutively active cytomegalovirus (CMV) promoter (ptdTomato-N1). The stably transfected cell line was named HEK-ptdTomato-N1 8. This cytotoxicity biosensor was tested by ionizing radiation (X-rays and accelerated heavy ions) exposure. As biological endpoints, the proliferation kinetics and the cell density reached 100 h after irradiation reflected by constitutive expression of the tdTomato were investigated. Both were reduced dose-dependently after radiation exposure. Finally, the cell line was used for biological weighting of heavy ions of different linear energy transfer (LET) as space-relevant radiation quality. The relative biological effectiveness of accelerated heavy ions in reducing cellular proliferation peaked at an LET of 91 keV/μm. The results of this study demonstrate that the HEK-ptdTomato-N1 reporter cell line can be used as a fast and reliable biosensor system for detection of cytotoxic damage caused by ionizing radiation.

  16. The biochemistry and molecular biology of xenobiotic polymer degradation by microorganisms.

    PubMed

    Kawai, Fusako

    2010-01-01

    Research on microbial degradation of xenobiotic polymers has been underway for more than 40 years. It has exploited a new field not only in applied microbiology but also in environmental microbiology, and has greatly contributed to polymer science by initiating the design of biodegradable polymers. Owing to the development of analytical tools and technology, molecular biological and biochemical advances have made it possible to prospect for degrading microorganisms in the environment and to determine the mechanisms involved in biodegradation when xenobiotic polymers are introduced into the environment and are exposed to microbial attack. In this review, the molecular biological and biochemical aspects of the microbial degradation of xenobiotic polymers are summarized, and possible applications of potent microorganisms, enzymes, and genes in environmental biotechnology are suggested.

  17. The Porosity of Autonomy: Social and Biological Constitution of the Patient in Biomedicine.

    PubMed

    Beever, Jonathan; Morar, Nicolae

    2016-01-01

    The nature and role of the patient in biomedicine comprise issues central to bioethical inquiry. Given its developmental history grounded firmly in a backlash against 20th-century cases of egregious human subjects abuse, contemporary medical bioethics has come to rely on a fundamental assumption: the unit of care (and the unit of value) is the autonomous self-directing patient. In this article we examine first the structure of the feminist social critique of autonomy. Then we show that a parallel argument can be made against relational autonomy as well, demonstrating how this second concept of autonomy fails to take sufficiently into account an array of biological determinants, particularly those from microbial biology. Finally, in light of this biological critique, we question whether or to what extent any relevant and meaningful view of autonomy can be recovered in the contemporary landscape of bioethics.

  18. Teleology and its constitutive role for biology as the science of organized systems in nature.

    PubMed

    Toepfer, Georg

    2012-03-01

    'Nothing in biology makes sense, except in the light of teleology'. This could be the first sentence in a textbook about the methodology of biology. The fundamental concepts in biology, e.g. 'organism' and 'ecosystem', are only intelligible given a teleological framework. Since early modern times, teleology has often been considered methodologically unscientific. With the acceptance of evolutionary theory, one popular strategy for accommodating teleological reasoning was to explain it by reference to selection in the past: functions were reconstructed as 'selected effects'. But the theory of evolution obviously presupposes the existence of organisms as organized and regulated, i.e. functional systems. Therefore, evolutionary theory cannot provide the foundation for teleology. The underlying reason for the central methodological role of teleology in biology is not its potential to offer particular forms of (evolutionary) explanations for the presence of parts, but rather an ontological one: organisms and other basic biological entities do not exist as physical bodies do, as amounts of matter with a definite form. Rather, they are dynamic systems in stable equilibrium; despite changes of their matter and form (in metabolism and metamorphosis) they maintain their identity. What remains constant in these kinds of systems is their 'organization', i.e. the causal pattern of interdependence of parts with certain effects of each part being relevant for the working of the system. Teleological analysis consists in the identification of these system-relevant effects and at the same time of the system as a whole. Therefore, the identity of biological systems cannot be specified without teleological reasoning. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. [Kinetic model of enhanced biological phosphorus removal with mixed acetic and propionic acids as carbon sources. (I): Model constitution].

    PubMed

    Zhang, Chao; Chen, Yin-Guang

    2013-03-01

    Based on activated sludge model No. 2 (ASM2), the anaerobic/aerobic kinetic model of phosphorus-accumulating organisms (PAO) was established with mixed short-chain fatty acids (SCFAs) as the base substance in enhanced biological phosphorus removal process. The characteristic of the PAO model was that the anaerobic metabolism rates of glycogen degradation, poly-beta-hydroxyalkanoates synthesis and polyphosphate hydrolysis were expressed by SCFAs uptake equation, and the effects of anaerobic maintenance on kinetics and stoichiometry were considered. The PAO kinetic model was composed of 3 soluble components, 4 particulate components and a pH parameter, which constituted the matrix of stoichiometric coefficients. On the basis of PAO model, the GAO kinetic model was established, which included 7 processes, and phosphorus content influenced the aerobic metabolism only.

  20. Chemical and biological properties of supramolecular polymer systems based on oligocaprolactones.

    PubMed

    Dankers, Patricia Y W; van Leeuwen, Ellen N M; van Gemert, Gaby M L; Spiering, A J H; Harmsen, Martin C; Brouwer, Linda A; Janssen, Henk M; Bosman, Anton W; van Luyn, Marja J A; Meijer, E W

    2006-11-01

    We show that materials with a diverse range of mechanical and biological properties can be obtained using a modular approach by simply mixing different ratios of oligocaprolactones that are either end-functionalized or chain-extended with quadruple hydrogen bonding ureido-pyrimidinone (UPy) moieties. The use of two UPy-synthons allows for easy synthesis of UPy-modified polymers resulting in high yields. Comparison of end-functionalized UPy-polymers with chain-extended UPy-polymers shows that these polymers behave distinctively different regarding their material and biological properties. The end-modified UPy-polymer is rather stiff and brittle due to its high crystallinity. Disks made of this material fractures after subcutaneous implantation. The material shows a low inflammatory response which is accompanied by the formation of a fibrous capsule, reflecting the inertness of the material. The chain-extended UPy-material on the contrary is practically free of crystalline domains and shows clear flexible properties. This material deforms after in-vivo implantation, accompanied with cellular infiltration. By mixing both polymers, materials with intermediate properties concerning their mechanical and biological behaviour can be obtained. Surprisingly, a 20:80 mixture of both polymers with the chain-extended UPy-polymer in excess shows flexible properties without visible deformation upon implantation for 42 days. This mixture, a blend formed by intimate mixing through UPy-UPy interaction, also shows a mild tissue response accompanied with the formation of a thin capsule. The material does not become more crystalline upon implantation. Hence, this mixture might be an ideal scaffold material for soft tissue engineering due to its flexibility and diminished fibrous tissue formation, and illustrates the strength of the modular approach.

  1. Dynamics of Polymer Molecules with Sacrificial Bond and Hidden Length Systems: Towards a Physically-Based Mesoscopic Constitutive Law

    PubMed Central

    Elbanna, Ahmed E.; Carlson, Jean M.

    2013-01-01

    We investigate the entropic force-elongation behavior of a polymer chain in the presence of the sacrificial bond and hidden length (SBHL) system observed experimentally in many biomaterials. We show that in most cases the SBHL system leads to a significant increase in toughness. However, the presence of a large number of bonds or relatively strong bonds in the SBHL system can reduce the net gain in toughness. We also incorporate the polymer model into a network of polymers with random properties (e.g., contour length, number and strength of sacrificial bonds, length of hidden loops). This allows us to derive a physically-based mesoscopic force-displacement law that governs the collective behavior. PMID:23565135

  2. Polymer science and biology: structure and dynamics at multiple scales

    PubMed Central

    2012-01-01

    I give a brief, biased survey of some recent problems in molecular and cell biology from the perspective of physical science, with a few answers, but a great many questions, challenges and opportunities. PMID:19048987

  3. Development of modified release gliclazide biological macromolecules using natural biodegradable polymers.

    PubMed

    Prajapati, Vipulkumar D; Mashru, Krupa H; Solanki, Himanshu K; Jani, Girish K

    2013-04-01

    Modified release biological macromolecules (beads) of gliclazide using sodium alginate combined with either gellan gum or pectin in different ratios were prepared by Ionotropic gelation method. Biological macromolecules were evaluated for different physico-chemical parameters. Increase in polymers proportion showed difficulty in production of biological macromolecules due to high viscosity of dispersion. As the polymer concentration increases, the swelling and entrapment efficiency of drug increased. Compared to all other batches and commercial modified release gliclazide tablet, formulated biological macromolecules of sodium alginate with pectin (2:1 ratio) and with gellan gum (6:0.75 ratio) exhibited spherical shape, biphasic in vitro release profile and initial high drug release followed by moderate release up to 12 h as matrix diffusion kinetics and Higuchi model as well as Korsmeyer model. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Multicolor Conjugated Polymer Dots for Biological Fluorescence Imaging

    PubMed Central

    Wu, Changfeng; Bull, Barbara; Szymanski, Craig; Christensen, Kenneth; McNeill, Jason

    2009-01-01

    Highly fluorescent conjugated polymer dots were developed for demanding applications such as fluorescence imaging in live cells. These nanoparticles exhibit small particle diameters, extraordinary fluorescence brightness, and excellent photostability. Single particle fluorescence imaging and kinetic studies indicate much higher emission rates (∼108 s-1) and little or no blinking of the nanoparticles as compared to typical results for single dye molecules and quantum dots. Analysis of single particle photobleaching trajectories reveals excellent photostability — as many as 109 or more photons emitted per nanoparticle prior to irreversible photobleaching. The superior figures of merit of these new fluorescent probes, together with the demonstration of cellular imaging, indicate their enormous potential for demanding fluorescence-based imaging and sensing applications such as high speed super-resolution single molecule/particle tracking and highly sensitive assays. PMID:19206410

  5. Multifunctionalized polymer microcapsules: novel tools for biological and pharmacological applications.

    PubMed

    Sukhorukov, Gleb B; Rogach, Andrey L; Garstka, Malgorzata; Springer, Sebastian; Parak, Wolfgang J; Muñoz-Javier, Almudena; Kreft, Oliver; Skirtach, Andre G; Susha, Andrei S; Ramaye, Yannic; Palankar, Raghavendra; Winterhalter, Mathias

    2007-06-01

    We describe recent developments with multifunctional nanoengineered polymer capsules. In addition to their obvious use as a delivery system, multifunctional nanocontainers find wide application in enzymatic catalysis, controlled release, and directed drug delivery in medicine. The multifunctionality is provided by the following components: 1) Luminescent semiconductor nanocrystals (quantum dots) that facilitate imaging and identification of different capsules, 2) superparamagnetic nanoparticles that allow manipulation of the capsules in a magnetic field, 3) surface coatings, which target the capsules to desired cells, 4) metallic nanoparticles in the capsule wall that act as an absorbing antenna for electromagnetic fields and provide heat for controlled release, and 5) enzymes and pharmaceutical agents that allow specific reactions. The unique advantage of multifunctional microcapsules in comparison to other systems is that they can be simultaneously loaded/functionalized with the above components, allowing for the combination of their properties in a single object.

  6. Biologically Inspired Polymer Microfibrillar Arrays for Mask Sealing

    DTIC Science & Technology

    2009-04-01

    Mask sealing Fibrillar adhesion Face masks Gecko adhesion Adhesion 16. SECURITY CLASSIFICATION OF: a. REPORT U b. ABSTRACT U c. THIS PAGE...donning practices. One promising area is biologically inspired dry adhesives. Geckos , spiders, beetles, flies, and many other climbing lizards and

  7. Mechanically switchable polymer fibers for sensing in biological conditions

    NASA Astrophysics Data System (ADS)

    McMillan, Sean; Rader, Chris; Jorfi, Mehdi; Pickrell, Gary; Foster, E. Johan

    2017-02-01

    The area of in vivo sensing using optical fibers commonly uses materials such as silica and polymethyl methacrylate, both of which possess much higher modulus than human tissue. The mechanical mismatch between materials and living tissue has been seen to cause higher levels of glial encapsulation, scarring, and inflammation, leading to failure of the implanted medical device. We present the use of a fiber made from polyvinyl alcohol (PVA) for use as an implantable sensor as it is an easy to work with functionalized polymer that undergoes a transition from rigid to soft when introduced to water. This ability to switch from stiff to soft reduces the severity of the immune response. The fabricated PVA fibers labeled with fluorescein for sensing applications showed excellent response to various stimuli while exhibiting mechanical switchability. For the dry fibers, a tensile storage modulus of 4700 MPa was measured, which fell sharply to 145 MPa upon wetting. The fibers showed excellent response to changing pH levels, producing values that were detectable in a range consistent with those seen in the literature and in proposed applications. The results show that these mechanically switchable fibers are a viable option for future sensing applications.

  8. [Distribution of biological particles in two-phase systems of water soluble polymers and salts].

    PubMed

    Kononova, O A; Gorovaia, T B; Tiutiunnikov, A V; Prokhorova, N V; Tarasevich, I V; Khramov, E N

    2000-01-01

    The paper discusses the problems of purification of Provachek's rickettsias used to prepare typhus vaccines and diagnostic kits. The currently available agents contain many admixtures of rickettsias products, more commonly yolk and chick embryo yolk sack cell detritus, which make it impossible to determine the true antigenic properties of rickettsias in the context of protection and diagnosis. By applying the well-known principle of distribution of biological particles in the two-phase systems of water soluble polymers, investigations were made to examine the distribution of rickettsias and their infected biological mass in the system: polyethylene glycol-6600, sodium-500 dextran sulfate, potassium phosphate, sodium chloride in order to prepare agents of pure rickettsias. It has been found that rickettsias are distributed in the polymer-enriched phase, their number and the degree of purity when isolated from the infected biological mass depends on the capacity of an interphase wherein tissue detritus sorption occurs.

  9. The biological response to nanometre-sized polymer particles

    PubMed Central

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L.; Ingham, Eileen; Fisher, John; Tipper, Joanne L.

    2015-01-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1–1.0 μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20 nm, 60 nm, 200 nm and 1.0 μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20 nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100 μm3 particles per cell after 12 and 24 h. The micrometre-size UHMWPE wear particles (0.1–1.0 μm) and 60 nm, 200 nm and 1.0 μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50 nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  10. Identification of Novel Activators of Constitutive Androstane Receptor from FDA-approved Drugs by Integrated Computational and Biological Approaches

    PubMed Central

    Lynch, Caitlin; Pan, Yongmei; Li, Linhao; Ferguson, Stephen S.; Xia, Menghang; Swaan, Peter W.; Wang, Hongbing

    2012-01-01

    Purpose The constitutive androstane receptor (CAR, NR1I3) is a xenobiotic sensor governing the transcription of numerous hepatic genes associated with drug metabolism and clearance. Recent evidence suggests that CAR also modulates energy homeostasis and cancer development. Thus, identification of novel human (h) CAR activators is of both clinical importance and scientific interest. Methods Docking and ligand-based structure-activity models were used for virtual screening of a database containing over 2000 FDA-approved drugs. Identified lead compounds were evaluated in cell-based reporter assays to determine hCAR activation. Potential activators were further tested in human primary hepatocytes (HPHs) for the expression of the prototypical hCAR target gene CYP2B6. Results Nineteen lead compounds with optimal modeling parameters were selected for biological evaluation. Seven of the 19 leads exhibited moderate to potent activation of hCAR. Five out of the seven compounds translocated hCAR from the cytoplasm to the nucleus of HPHs in a concentration-dependent manner. These compounds also induce the expression of CYP2B6 in HPHs with rank-order of efficacies closely resembling that of hCAR activation. Conclusion These results indicate that our strategically integrated approaches are effective in the identification of novel hCAR modulators, which may function as valuable research tools or potential therapeutic molecules. PMID:23090669

  11. Identification of novel activators of constitutive androstane receptor from FDA-approved drugs by integrated computational and biological approaches.

    PubMed

    Lynch, Caitlin; Pan, Yongmei; Li, Linhao; Ferguson, Stephen S; Xia, Menghang; Swaan, Peter W; Wang, Hongbing

    2013-02-01

    The constitutive androstane receptor (CAR, NR1I3) is a xenobiotic sensor governing the transcription of numerous hepatic genes associated with drug metabolism and clearance. Recent evidence suggests that CAR also modulates energy homeostasis and cancer development. Thus, identification of novel human (h) CAR activators is of both clinical importance and scientific interest. Docking and ligand-based structure-activity models were used for virtual screening of a database containing over 2000 FDA-approved drugs. Identified lead compounds were evaluated in cell-based reporter assays to determine hCAR activation. Potential activators were further tested in human primary hepatocytes (HPHs) for the expression of the prototypical hCAR target gene CYP2B6. Nineteen lead compounds with optimal modeling parameters were selected for biological evaluation. Seven of the 19 leads exhibited moderate to potent activation of hCAR. Five out of the seven compounds translocated hCAR from the cytoplasm to the nucleus of HPHs in a concentration-dependent manner. These compounds also induce the expression of CYP2B6 in HPHs with rank-order of efficacies closely resembling that of hCAR activation. These results indicate that our strategically integrated approaches are effective in the identification of novel hCAR modulators, which may function as valuable research tools or potential therapeutic molecules.

  12. Selective extraction of proteins and other macromolecules from biological samples using molecular imprinted polymers.

    PubMed

    Stevenson, Derek; El-Sharif, Hazim F; Reddy, Subrayal M

    2016-11-01

    The accurate determination of intact macromolecules in biological samples, such as blood, plasma, serum, urine, tissue and feces is a challenging problem. The increased interest in macromolecules both as candidate drugs and as biomarkers for diagnostic purposes means that new method development approaches are needed. This review charts developments in the use of molecularly imprinted polymers first for small-molecular-mass compounds then for proteins and other macromolecules. Examples of the development of molecularly imprinted polymers for macromolecules are highlighted. The two main application areas to date are sensors and separation science, particularly SPE. Examples include peptides and polypeptides, lysozyme, hemoglobin, ovalbumin, bovine serum albumin and viruses.

  13. Advantages of a 3-parameter reduced constitutive model for the measurement of polymers elastic modulus using tensile tests

    NASA Astrophysics Data System (ADS)

    Blaise, A.; André, S.; Delobelle, P.; Meshaka, Y.; Cunat, C.

    2016-11-01

    Exact measurements of the rheological parameters of time-dependent materials are crucial to improve our understanding of their intimate relation to the internal bulk microstructure. Concerning solid polymers and the apparently simple determination of Young's modulus in tensile tests, international standards rely on basic protocols that are known to lead to erroneous values. This paper describes an approach allowing a correct measurement of the instantaneous elastic modulus of polymers by a tensile test. It is based on the use of an appropriate reduced model to describe the behavior of the material up to great strains, together with well-established principles of parameter estimation in engineering science. These principles are objective tools that are used to determine which parameters of a model can be correctly identified according to the informational content of a given data set. The assessment of the methodology and of the measurements is accomplished by comparing the results with those obtained from two other physical experiments, probing the material response at small temporal and length scales, namely, ultrasound measurements with excitation at 5 MHz and modulated nanoindentation tests over a few nanometers of amplitude.

  14. EPR imaging of diffusional processes in biologically relevant polymers

    NASA Astrophysics Data System (ADS)

    Berliner, Lawrence J.; Fujii, Hirotada

    Diffusion processes in biological tissue are important problems for noninvasive investigation. As a model study, this work addresses the diffusion of an electrolyte buffer (Krebs) solution containing a nitroxide spin probe into a cylindrical polyacrylamide gel rod. The nitroxide spin density distribution was imaged at 1.6 GHz in gel cross sections at various time intervals for both homogeneous radial diffusion and inhomogeneous diffusion. A one-dimensional radial diffusion constant was calculated for the nitroxide spin probe, TEMPOL, of 3.7 ± 0.7 × 10 -6 cm 2/s at ambient temperature. The EPR spectrometer, using low-field flat-loop surface coils (H. Nishikawa, H. Fujii, and L. J. Berliner, J. Magn. Reson.62, 79 (1985)), showed minimal dielectric or magnetic losses in sensitity for electrolyte vs nondielectric samples.

  15. Development of a Systems Computational Model to Investigate Early Biological Events in Hepatic Activation of Constitutive Androstane Receptor (CAR) by Phenobarbital

    EPA Science Inventory

    Activation of the nuclear receptor CAR (constitutive active/androstane receptor) is implicated in the control several key biological events such as metabolic pathways. Here, we combined data from literature with information obtained from in vitro assays in the US EPA ToxCast dat...

  16. Development of a Systems Computational Model to Investigate Early Biological Events in Hepatic Activation of Constitutive Androstane Receptor (CAR) by Phenobarbital

    EPA Science Inventory

    Activation of the nuclear receptor CAR (constitutive active/androstane receptor) is implicated in the control several key biological events such as metabolic pathways. Here, we combined data from literature with information obtained from in vitro assays in the US EPA ToxCast dat...

  17. Comparing the mechanical properties of high performances polymer nanocomposites from biological sources.

    PubMed

    Dufresne, Alain

    2006-02-01

    There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose and chitin are classical examples of these reinforcing elements, which occur as whisker-like microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. Starch is another example of natural semicrystalline polymer that is produced by many plants and occurs as microscopic granules. It acts as a storage polymer in cereals and tubers. These abundant and natural polymers can be used to create high performance nanocomposites presenting outstanding properties. Aqueous suspensions of crystallites can be prepared by acid hydrolysis of the purified substrates. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. For cellulose and chitin, these monocrystals appear as rod-like nanoparticles which dimensions depend on the biological source of the substrate. In the case of starch they consist of platelet-like nanoparticles. High reinforcing capability was reported resulting from the intrinsic chemical nature of these polymers and from their hierarchical structure. During the last decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrices.

  18. A two-phase hyperelastic-viscoplastic constitutive model for semi-crystalline polymers: application to polyethylene materials with a variable range of crystal fractions.

    PubMed

    Abdul-Hameed, H; Messager, T; Ayoub, G; Zaïri, F; Naït-Abdelaziz, M; Qu, Z; Zaïri, F

    2014-09-01

    Polyethylene-based polymers as biomedical materials can contribute to a wide range of biomechanical applications. Therefore, it is important to identify, analyse, and predict with precision their mechanical behaviour. Polyethylene materials are semi-crystalline systems consisting of both amorphous and crystalline phases interacting in a rather complex manner. When the amorphous phase is in the rubbery state, the mechanical behaviour is strongly dependent on the crystal fraction, therefore leading to essentially thermoplastic or elastomeric responses. In this study, the finite deformation stress-strain response of polyethylene materials is modelled by considering these semi-crystalline polymers as two-phase heterogeneous media in order to provide insight into the role of crystalline and amorphous phases on the macro-behaviour and on the material deformation resistances, i.e. intermolecular and network resistances. A hyperelastic-viscoplastic model is developed in contemplation of representing the overall mechanical response of polyethylene materials under large deformation. An evolutionary optimization procedure based on a genetic algorithm is developed to identify the model parameters at different strain rates. The identification results show good agreement with experimental data, demonstrating the usefulness of the proposed approach: the constitutive model, with only one set of identified parameters, allows reproducing the stress-strain behaviour of polyethylene materials exhibiting a wide range of crystallinities, the crystal content becoming the only variable of the model.

  19. Optical diagnostics of biological tissue cells during their cultivation in polymers

    SciTech Connect

    Letuta, S N; Maryakhina, V S; Rakhmatullin, R R

    2011-04-30

    The specific features of long-term luminescence of exogenous molecular probes in cells of pathogenic and normal biological tissues, cultivated on a solid nutrient medium, have been investigated by laser kinetic fluorimetry. It is proposed to use the Hyamatrix biopolymer as a nutrient medium. This polymer is formed on the basis of native, chemically unmodified hyaluronic acid and contains amino acids, microelements, vitamins, and other components. The possibility of using the obtained results to develop an alternative method of fluorescent diagnostics of biological tissues is discussed. (optical technologies in biophysics and medicine)

  20. Optical diagnostics of biological tissue cells during their cultivation in polymers

    NASA Astrophysics Data System (ADS)

    Letuta, S. N.; Maryakhina, V. S.; Rakhmatullin, R. R.

    2011-04-01

    The specific features of long-term luminescence of exogenous molecular probes in cells of pathogenic and normal biological tissues, cultivated on a solid nutrient medium, have been investigated by laser kinetic fluorimetry. It is proposed to use the Hyamatrix biopolymer as a nutrient medium. This polymer is formed on the basis of native, chemically unmodified hyaluronic acid and contains amino acids, microelements, vitamins, and other components. The possibility of using the obtained results to develop an alternative method of fluorescent diagnostics of biological tissues is discussed.

  1. Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers.

    SciTech Connect

    Parrot, I. M.; Urban, Volker S; Gardner, K. H.; Forsyth, V. T.

    2005-04-01

    The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar{reg_sign} or Twaron{reg_sign}.

  2. High Temperature Extends the Range of Size Discrimination of Nonionic Polymers by a Biological Nanopore

    NASA Astrophysics Data System (ADS)

    Piguet, Fabien; Ouldali, Hadjer; Discala, Françoise; Breton, Marie-France; Behrends, Jan C.; Pelta, Juan; Oukhaled, Abdelghani

    2016-12-01

    We explore the effect of temperature on the interaction of polydisperse mixtures of nonionic poly(ethylene glycol) (PEG) polymers of different average molar masses with the biological nanopore α-hemolysin. In contrast with what has been previously observed with various nanopores and analytes, we find that, for PEGs larger than a threshold molar mass (2000 g/mol, PEG 2000), increasing temperature increases the duration of the PEG/nanopore interaction. In the case of PEG 3400 the duration increases by up to a factor of 100 when the temperature increases from 5 °C to 45 °C. Importantly, we find that increasing temperature extends the polymer size range of application of nanopore-based single-molecule mass spectrometry (Np-SMMS)-type size discrimination. Indeed, in the case of PEG 3400, discrimination of individual molecular species of different monomer number is impossible at room temperature but is achieved when the temperature is raised to 45 °C. We interpret our observations as the consequence of a decrease of PEG solubility and a collapse of PEG molecules with higher temperatures. In addition to expanding the range of application of Np-SMMS to larger nonionic polymers, our findings highlight the crucial role of the polymer solubility for the nanopore detection.

  3. High Temperature Extends the Range of Size Discrimination of Nonionic Polymers by a Biological Nanopore

    PubMed Central

    Piguet, Fabien; Ouldali, Hadjer; Discala, Françoise; Breton, Marie-France; Behrends, Jan C.; Pelta, Juan; Oukhaled, Abdelghani

    2016-01-01

    We explore the effect of temperature on the interaction of polydisperse mixtures of nonionic poly(ethylene glycol) (PEG) polymers of different average molar masses with the biological nanopore α-hemolysin. In contrast with what has been previously observed with various nanopores and analytes, we find that, for PEGs larger than a threshold molar mass (2000 g/mol, PEG 2000), increasing temperature increases the duration of the PEG/nanopore interaction. In the case of PEG 3400 the duration increases by up to a factor of 100 when the temperature increases from 5 °C to 45 °C. Importantly, we find that increasing temperature extends the polymer size range of application of nanopore-based single-molecule mass spectrometry (Np-SMMS)-type size discrimination. Indeed, in the case of PEG 3400, discrimination of individual molecular species of different monomer number is impossible at room temperature but is achieved when the temperature is raised to 45 °C. We interpret our observations as the consequence of a decrease of PEG solubility and a collapse of PEG molecules with higher temperatures. In addition to expanding the range of application of Np-SMMS to larger nonionic polymers, our findings highlight the crucial role of the polymer solubility for the nanopore detection. PMID:27924860

  4. Path-Integration Computation of the Transport Properties of Polymers Nanoparticles and Complex Biological Structures

    NASA Astrophysics Data System (ADS)

    Douglas, Jack

    2014-03-01

    finite cross-section, DNA, nanoparticles with grafted chain layers and knotted polymers. The path-integration method, which grew up from research in Karl Freed's group, is evidently a powerful tool for computing basic transport properties of complex-shaped objects and should find increasing application in polymer science, nanotechnological applications and biology.

  5. Prediction of intracellular storage polymers using quantitative image analysis in enhanced biological phosphorus removal systems.

    PubMed

    Mesquita, Daniela P; Leal, Cristiano; Cunha, Jorge R; Oehmen, Adrian; Amaral, A Luís; Reis, Maria A M; Ferreira, Eugénio C

    2013-04-03

    The present study focuses on predicting the concentration of intracellular storage polymers in enhanced biological phosphorus removal (EBPR) systems. For that purpose, quantitative image analysis techniques were developed for determining the intracellular concentrations of PHA (PHB and PHV) with Nile blue and glycogen with aniline blue staining. Partial least squares (PLS) were used to predict the standard analytical values of these polymers by the proposed methodology. Identification of the aerobic and anaerobic stages proved to be crucial for improving the assessment of PHA, PHB and PHV intracellular concentrations. Current Nile blue based methodology can be seen as a feasible starting point for further enhancement. Glycogen detection based on the developed aniline blue staining methodology combined with the image analysis data proved to be a promising technique, toward the elimination of the need for analytical off-line measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Extension of in vivo half-life of biologically active molecules by XTEN protein polymers.

    PubMed

    Podust, Vladimir N; Balan, Sibu; Sim, Bee-Cheng; Coyle, Michael P; Ernst, Ulrich; Peters, Robert T; Schellenberger, Volker

    2016-10-28

    XTEN™ is a class of unstructured hydrophilic, biodegradable protein polymers designed to increase the half-lives of therapeutic peptides and proteins. XTEN polymers and XTEN fusion proteins are typically expressed in Escherichia coli and purified by conventional protein chromatography as monodisperse polypeptides of exact length and sequence. Unstructured XTEN polypeptides have hydrodynamic volumes significantly larger than typical globular proteins of similar mass, thus imparting a bulking effect to the therapeutic payloads attached to them. Since their invention, XTEN polypeptides have been utilized to extend the half-lives of a variety of peptide- and protein-based therapeutics. Multiple clinical and preclinical studies and related drug discovery and development efforts are in progress. This review details the most current understanding of physicochemical properties and biological behavior of XTEN and XTENylated molecules. Additionally, the development path and status of several advanced drug discovery and development efforts are highlighted.

  7. The extracellular constitutive production of chitin deacetylase in Metarhizium anisopliae: possible edge to entomopathogenic fungi in the biological control of insect pests.

    PubMed

    Nahar, Pallavi; Ghormade, Vandana; Deshpande, Mukund V

    2004-02-01

    The possible contribution of extracellular constitutively produced chitin deacetylase by Metarhizium anisopliae in the process of insect pathogenesis has been evaluated. Chitin deacetylase converts chitin, a beta-1,4-linked N-acetylglucosamine polymer, into its deacetylated form chitosan, a glucosamine polymer. When grown in a yeast extract-peptone medium, M. anisopliae constitutively produced the enzymes protease, lipase, and two chitin-metabolizing enzymes, viz. chitin deacetylase (CDA) and chitosanase. Chitinase activity was induced in chitin-containing medium. Staining of 7.5% native polyacrylamide gels at pH 8.9 revealed CDA activity in three bands. SDS-PAGE showed that the apparent molecular masses of the three isoforms were 70, 37, and 26 kDa, respectively. Solubilized melanin (10microg) inhibited chitinase activity, whereas CDA was unaffected. Following germination of M. anisopliae conidia on isolated Helicoverpa armigera, cuticle revealed the presence of chitosan by staining with 3-methyl-2-benzothiazoline hydrazone. Blue patches of chitosan were observed on cuticle, indicating conversion of chitin to chitosan. Hydrolysis of chitin with constitutively produced enzymes of M. anisopliae suggested that CDA along with chitosanase contributed significantly to chitin hydrolysis. Thus, chitin deacetylase was important in initiating pathogenesis of M. anisopliae softening the insect cuticle to aid mycelial penetration. Evaluation of CDA and chitinase activities in other isolates of Metarhizium showed that those strains had low chitinase activity but high CDA activity. Chemical assays of M. anisopliae cell wall composition revealed the presence of chitosan. CDA may have a dual role in modifying the insect cuticular chitin for easy penetration as well as for altering its own cell walls for defense from insect chitinase.

  8. The use of electrochemically grown polymers on metallized electrodes to reduce electrode fouling in biological matrices.

    PubMed

    Daly, D J; O'Sullivan, C K; Guilbault, G G

    2000-02-01

    The use of electrochemically grown polymers has expanded dramatically in the last couple of years, and they are now well established as membranes for immobilizing components. The evidence here for their anti-fouling properties is good. The poly(1,3-diaminobenzene)-covered electrodes performed well in the buffer, urine, plasma and serum samples, but not so well in the blood. The Ru/Rh/Pt, Rh/Rh and the Pt-on-glassy carbon electrodes covered with poly(1,3-diaminobenzene) were the best electrodes in the blood. The Pt disc seemed to exhibit the largest irrepeatability in most of the biological matrices.

  9. Terbium-based coordination polymer nanoparticles for detection of ciprofloxacin in tablets and biological fluids.

    PubMed

    Tan, Hongliang; Zhang, Li; Ma, Chanjiao; Song, Yonghai; Xu, Fugang; Chen, Shouhui; Wang, Li

    2013-11-27

    The metal-organic coordination polymers with tunable structures and properties have been rapidly emerging as very important functional materials. In this work, we prepared terbium (Tb(3+))-based coordination polymer nanoparticles (CPNPs) by employing adenine (Ad) as bridging ligands. The CPNPs was further used as a receptor reagent for ciprofloxacin (CF) detection in aqueous solution. Addition of CF induces a typical emission of Tb(3+) due to the formation of Ad/Tb-CF complex and the sensitization of CF. The fluorescent intensity of Tb(3+) was enhanced linearly with increasing the CF concentration from 60 nM to 14 μM. The detection limit for CF in aqueous solution is 60 nM. The Ad/Tb CPNPs was successfully applied to detect CF in tablet and urine samples and showed a satisfactory result. Compared with other methods, the proposed method is advantageous because that it provides a very simple strategy for CF detection, which does not require complicated sample pretreatment processes or special reaction media. The proposed strategy could be contributed to expand the potential applications of lanthanide coordination polymers in biological and environmental fields.

  10. Polymer coatings that display specific biological signals while preventing nonspecific interactions.

    PubMed

    Ameringer, Thomas; Fransen, Peter; Bean, Penny; Johnson, Graham; Pereira, Suzanne; Evans, Richard A; Thissen, Helmut; Meagher, Laurence

    2012-02-01

    Control over cell-material surface interactions is the key to many new and improved biomedical devices. It can only be achieved if interactions that are mediated by nonspecifically adsorbed serum proteins are minimized and if cells instead respond to specific ligand molecules presented on the surface. Here, we present a simple yet effective surface modification method that allows for the covalent coupling and presentation of specific biological signals on coatings which have significantly reduced nonspecific biointerfacial interactions. To achieve this we synthesized bottle brush type copolymers consisting of poly(ethylene glycol) methyl ether methacrylate and (meth)acrylates providing activated NHS ester groups as well as different spacer lengths between the NHS groups and the polymer backbone. Copolymers containing different molar ratios of these monomers were grafted to amine functionalized polystyrene cell culture substrates, followed by the covalent immobilization of the cyclic peptides cRGDfK and cRADfK using residual NHS groups. Polymers were characterized by GPC and NMR and surface modification steps were analyzed using XPS. The cellular response was evaluated using HeLa cell attachment experiments. The results showed strong correlations between the effectiveness of the control over biointerfacial interactions and the polymer architecture. They also demonstrate that optimized fully synthetic copolymer coatings, which can be applied to a wide range of substrate materials, provide excellent control over biointerfacial interactions.

  11. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  12. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  13. Biological performance of functionalized biomedical polymers for potential applications as intraocular lens.

    PubMed

    Zheng, Zhiwen; Wang, Yingjun; Jiao, Yan; Zhai, Zhichen

    2016-08-01

    To study the biological performance of surface-modified biomedical polymer materials, a model of the functional mechanism of nonspecific adsorption resistance was constructed. Cell behavior on the surface and in vivo transplantation features of intraocular lens (IOL) materials, such as hydrophobic acrylic ester and polymethyl methacrylate (PMMA), were investigated. The results of cell adhesion and proliferation studies showed that the addition of hirudin can significantly resist epithelial cell adhesion, better than the pure amination process, and thereby inhibit excessive proliferation on the surface. Experiments on the eyes of rabbits indicated that the IOL surfaces with hirudin modification reduced the incidence of cell aggregation and inflammation. Combined with a study of protein-resistant layer construction with recombinant hirudin on the material surface, the mechanism of surface functionalization was determined. The biological performance indicated that nonspecific adsorption is greatly decreased due to the existence of amphiphilic ions or hydration layers, which lead to stability and long-term resistance to nonspecific adsorption. These results offer a theoretical basis for the use of traditional biomedical polymer materials in long-term clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1961-1967, 2016. © 2016 Wiley Periodicals, Inc.

  14. Real-Time Control of Biological Motor Activity using Graphene-polymer Hybrid Bioenergy Storage Device

    NASA Astrophysics Data System (ADS)

    Lee, Dong; Byun, Kyung-Eun; Choi, Dong; Kim, Eunji; Kim, Daesan; Seo, David; Yang, Heejun; Seo, Sunae; Hong, Seunghun; Hybrid Nanodevice Lab Team; Samsung Research Park Team

    2013-03-01

    Biological motors have been drawing an attention as a key component for highly efficient nanomechanical systems. For such applications, many researchers have tried to control the activity of motor proteins through various methods such as microfluidics or UV-active compounds. However, these methods have some limitations such as the incapability of controlling local biomotor activity and a slow response rate. Herein, we developed a graphene-polymer hybrid nanostructure-based bioenergy storage device which enables the real-time control of biomotor activity. In this strategy, graphene layers functionalized with amine groups were utilized as a transparent electrode supporting the motility of biomotors. And conducting polymer patterns doped with adenosine triphosphate (ATP) were electrically deposited on the graphene and utilized for the fast release of ATP by electrical stimuli through the graphene. Such controlled release of ATP allowed us to control the motility of actin filaments propelled by myosin biomotors in real time. This strategy should enable integrated nanodevices for the real-time control of biological motors to the nanodevices, which can be a significant stepping stone toward hybrid nanomechanical systems based on motor proteins.

  15. [Refusal of the biological proof practice and the harm of the law to effective judicial guardianship in constitutional jurisprudence].

    PubMed

    Herrán Ortiz, Ana Isabel

    2007-01-01

    The Spanish Constitution protects the free investigation of the paternity on its 39.2 the article, in which is granted that possibility. This right is not absolute, it has limits, but those limits will have to be interpreted in a restrictive way due to the principles based on it, such as the legal equality of children, and the integral protection of them. In view of this, the sentences are a very valuable element to delimit the aplication of this right, and establish its limitations.

  16. On the role of water molecules in the interface between biological systems and polymers.

    PubMed

    Tsuruta, Teiji

    2010-01-01

    aqueous medium could change in response to their chemical structure such as nature of ionic groups, the degree of branching, etc. Polysaccharides located at the utmost-outer layer of blood cells probably possess a loosened network structure to form soft biological surface where intermediate water predominates. Cellulose, on the other hand, has a common feature with PHEMA in the sense of predominance of the non-freezing water in its hydrated system. Note: The word 'biocompatibility' is used in general as the term evaluating properties of materials which do not cause adverse effect when the materials come into contact with living organisms, such as proteins, biological cells and tissues. This review paper primarily deals with 'biocompatibility' of polymer materials against various biological elements in blood flow system.

  17. Tuning the Biological Activity Profile of Antibacterial Polymers via Subunit Substitution Pattern

    PubMed Central

    2015-01-01

    Binary nylon-3 copolymers containing cationic and hydrophobic subunits can mimic the biological properties of host-defense peptides, but relationships between composition and activity are not yet well understood for these materials. Hydrophobic subunits in previously studied examples have been limited mostly to cycloalkane-derived structures, with cyclohexyl proving to be particularly promising. The present study evaluates alternative hydrophobic subunits that are isomeric or nearly isomeric with the cyclohexyl example; each has four sp3 carbons in the side chains. The results show that varying the substitution pattern of the hydrophobic subunit leads to relatively small changes in antibacterial activity but causes significant changes in hemolytic activity. We hypothesize that these differences in biological activity profile arise, at least in part, from variations among the conformational propensities of the hydrophobic subunits. The α,α,β,β-tetramethyl unit is optimal among the subunits we have examined, providing copolymers with potent antibacterial activity and excellent prokaryote vs eukaryote selectivity. Bacteria do not readily develop resistance to the new antibacterial nylon-3 copolymers. These findings suggest that variation in subunit conformational properties could be generally valuable in the development of synthetic polymers for biological applications. PMID:24601599

  18. Dynamics of intracellular polymers in enhanced biological phosphorus removal processes under different organic carbon concentrations.

    PubMed

    Xing, Lizhen; Ren, Li; Tang, Bo; Wu, Guangxue; Guan, Yuntao

    2013-01-01

    Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

  19. Dynamics of Intracellular Polymers in Enhanced Biological Phosphorus Removal Processes under Different Organic Carbon Concentrations

    PubMed Central

    Xing, Lizhen; Ren, Li; Tang, Bo; Guan, Yuntao

    2013-01-01

    Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate. PMID:24381942

  20. Enhancement in biological response of Ag-nano composite polymer membranes using plasma treatment for fabrication of efficient bio materials

    NASA Astrophysics Data System (ADS)

    Agrawal, Narendra Kumar; Sharma, Tamanna Kumari; Chauhan, Manish; Agarwal, Ravi; Vijay, Y. K.; Swami, K. C.

    2016-05-01

    Biomaterials are nonviable material used in medical devices, intended to interact with biological systems, which are becoming necessary for the development of artificial material for biological systems such as artificial skin diaphragm, valves for heart and kidney, lenses for eye etc. Polymers having novel properties like antibacterial, antimicrobial, high adhesion, blood compatibility and wettability are most suitable for synthesis of biomaterial, but all of these properties does not exist in any natural or artificial polymeric material. Nano particles and plasma treatment can offer these properties to the polymers. Hence a new nano-biomaterial has been developed by modifying the surface and chemical properties of Ag nanocomposite polymer membranes (NCPM) by Argon ion plasma treatment. These membranes were characterized using different techniques for surface and chemical modifications occurred. Bacterial adhesion and wettability were also tested for these membranes, to show direct use of this new class of nano-biomaterial for biomedical applications.

  1. Heterogeneity of intracellular polymer storage states in enhanced biological phosphorus removal (EBPR)--observation and modeling.

    PubMed

    Bucci, Vanni; Majed, Nehreen; Hellweger, Ferdi L; Gu, April Z

    2012-03-20

    A number of agent-based models (ABMs) for biological wastewater treatment processes have been developed, but their skill in predicting heterogeneity of intracellular storage states has not been tested against observations due to the lack of analytical methods for measuring single-cell intracellular properties. Further, several mechanisms can produce and maintain heterogeneity (e.g., different histories, uneven division) and their relative importance has not been explored. This article presents an ABM for the enhanced biological phosphorus removal (EBPR) treatment process that resolves heterogeneity in three intracellular polymer storage compounds (i.e., polyphosphate, polyhydroxybutyrate, and glycogen) in three functional microbial populations (i.e., polyphosphate-accumulating, glycogen-accumulating, and ordinary heterotrophic organisms). Model predicted distributions were compared to those based on single-cell estimates obtained using a Raman microscopy method for a laboratory-scale sequencing batch reactor (SBR) system. The model can reproduce many features of the observed heterogeneity. Two methods for introducing heterogeneity were evaluated. First, biological variability in individual cell behavior was simulated by randomizing model parameters (e.g., maximum acetate uptake rate) at division. This method produced the best fit to the data. An optimization algorithm was used to determine the best variability (i.e., coefficient of variance) for each parameter, which suggests large variability in acetate uptake. Second, biological variability in individual cell states was simulated by randomizing state variables (e.g., internal nutrient) at division, which was not able to maintain heterogeneity because the memory in the internal states is too short. These results demonstrate the ability of ABM to predict heterogeneity and provide insights into the factors that contribute to it. Comparison of the ABM with an equivalent population-level model illustrates the effect

  2. Micro-processing of polymers and biological materials using high repetition rate femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Ding, Li

    High repetition rate femtosecond laser micro-processing has been applied to ophthalmological hydrogel polymers and ocular tissues to create novel refractive and diffractive structures. Through the optimization of laser irradiation conditions and material properties, this technology has become feasible for future industrial applications and clinical practices. A femtosecond laser micro-processing workstation has been designed and developed. Different experimental parameters of the workstation such as laser pulse duration, focusing lens, and translational stages have been described and discussed. Diffractive gratings and three-dimensional waveguides have been fabricated and characterized in hydrogel polymers, and refractive index modifications as large as + 0.06 have been observed within the laser-irradiated region. Raman spectroscopic studies have shown that our femtosecond laser micro-processing induces significant thermal accumulation, resulting in a densification of the polymer network and increasing the localized refractive index of polymers within the laser irradiated region. Different kinds of dye chromophores have been doped in hydrogel polymers to enhance the two-photon absorption during femtosecond laser micro-processing. As the result, laser scanning speed can be greatly increased while the large refractive index modifications remain. Femtosecond laser wavelength and pulse energy as well as water and dye concentration of the hydrogels are optimized. Lightly fixed ocular tissues such as corneas and lenses have been micro-processed by focused femtosecond laser pulses, and refractive index modifications without any tissue-breakdown are observed within the stromal layer of the corneas and the cortex of the lenses. Living corneas are doped with Sodium Fluorescein to increase the two-photon absorption during the laser micro-processing, and laser scanning speed can be greatly increased while inducing large refractive index modifications. No evidence of cell death

  3. From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

    NASA Astrophysics Data System (ADS)

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

    2016-09-01

    We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

  4. From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

    PubMed Central

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

    2016-01-01

    We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices. PMID:27622466

  5. From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance.

    PubMed

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P; Triantafyllou, Michael

    2016-09-13

    We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

  6. Tandem repeat polymers of a critical region of the human interferon-beta promoter exhibit a marked constitutive activity and enhanced responsiveness to transcriptional regulators in transfected HeLa cells.

    PubMed

    Dron, M; Rebouillat, D; Tovey, M G

    1992-10-01

    Multiple copy tandem repeats polymers of an authentic 30-bp region of the human interferon-beta (IFN-beta) promoter between positions-91 to -62 relative to the cap site or the hexanucleotide GAAAGT derived from this region, both acted as strong constitutive regulatory elements in transfected HeLa cells. Such polymers were unresponsive to treatment with IFN-alpha despite their considerable homology with the IFN-responsive elements of other genes but were highly responsive to treatment of HeLa cells with IFN-gamma. Virus induction of HeLa cells transfected with polymers of the 30-bp region linked to a CAT gene increased the activity of the reporter gene 500- to 2,000-fold over baseline levels. Treatment with IFN-alpha prior to virus induction did not increase further CAT activity. Cotransfection of HeLa cells with the CAT gene under the control of a 12-element tandem repeat polymer of the human IFN-beta promoter and an expression vector for the IRF-1 transcriptional activator markedly increased CAT activity while cotransfection of HeLa cells with the IFN-beta construct together with an expression vector for the transcriptional regulator IRF-2 markedly decreased CAT activity relative to cells transfected with the IFN-beta polymer alone.

  7. Conformational assembly and biological properties of collagen mimetic peptides and their thermally responsive polymer conjugates

    NASA Astrophysics Data System (ADS)

    Krishna, Ohm Divyam

    2011-12-01

    Collagens are one of the most abundant proteins found in body tissues and organs, endowing structural integrity, mechanical strength, and multiple biological functions. Destabilized collagen inside human body leads to various degenerative diseases (ex. osteoarthritis) and ageing. This has continued to motivate the design of synthetic peptides and bio-synthetic polypeptides to closely mimic the native collagens in terms of triple helix structure and stability, potential for higher order assembly, and biological properties. However, the widespread application of de novo collagens has been limited in part by the need for hydroxylated proline in the formation of stable triple helical structures. To address this continued need, a hydroxyproline-free, thermally stable collagen-mimetic peptide (CLP-Cys) was rationally designed via the incorporation of electrostatically stabilized amino acid triplets. CLP-Cys was synthesized via solid phase peptide synthesis. The formation and stability of the triple helical structure were indicated via circular dichroism (CD) experiments and confirmed via differential scanning calorimetry (DSC) results. CLP-Cys also self-assembled into nano-rods and micro-fibrils, as evidenced via a combination of dynamic light scattering and transmission electron microscopy. Given the high thermal stability and its propensity for higher-order assembly, CLP-Cys was further functionalized at both the ends with a thermally responsive polymer, poly(diethylene glycol methyl ether methacrylate), (PDEGMEMA) to synthesize a biohybrid triblock copolymer. The CD results indicated that the triple helical form is retained, the thermal unfolding is sustained and helix to coil transition is reversible in the triblock hybrid context. The LCST of PDEGMEMA homopolymer (26 °C) is increased (to 35 °C) upon conjugation to the hydrophilic collagen peptide domain. Further, a combination of static light scattering, Cryo-SEM, TEM and confocal microscopy elucidated that the

  8. Development and testing of new biologically-based polymers as advanced biocompatible contact lenses

    SciTech Connect

    Bertozzi, Carolyn R.

    2000-06-01

    Nature has evolved complex and elegant materials well suited to fulfill a myriad of functions. Lubricants, structural scaffolds and protective sheaths can all be found in nature, and these provide a rich source of inspiration for the rational design of materials for biomedical applications. Many biological materials are based in some fashion on hydrogels, the crosslinked polymers that absorb and hold water. Biological hydrogels contribute to processes as diverse as mineral nucleation during bone growth and protection and hydration of the cell surface. The carbohydrate layer that coats all living cells, often referred to as the glycocalyx, has hydrogel-like properties that keep cell surfaces well hydrated, segregated from neighboring cells, and resistant to non-specific protein deposition. With the molecular details of cell surface carbohydrates now in hand, adaptation of these structural motifs to synthetic materials is an appealing strategy for improving biocompatibility. The goal of this collaborative project between Prof. Bertozzi's research group, the Center for Advanced Materials at Lawrence Berkeley National Laboratory and Sunsoft Corporation was the design, synthesis and characterization of novel hydrogel polymers for improved soft contact lens materials. Our efforts were motivated by the urgent need for improved materials that allow extended wear, and essential feature for those whose occupation requires the use of contact lenses rather than traditional spectacles. Our strategy was to transplant the chemical features of cell surface molecules into contact lens materials so that they more closely resemble the tissue in which they reside. Specifically, we integrated carbohydrate molecules similar to those found on cell surfaces, and sulfoxide materials inspired by the properties of the carbohydrates, into hydrogels composed of biocompatible and manufacturable substrates. The new materials were characterized with respect to surface and bulk hydrophilicity, and

  9. Polymers as directing agents for motions of chemical and biological species

    NASA Astrophysics Data System (ADS)

    Tanyeri, Nihan Yonet

    This thesis involves descriptions of solid surface modifications with various polymeric materials which were used as a guiding agent for motion of chemical and biological species. Quasi-two dimensional poly(oligoethylene glycol) acrylate polymer brush based molecular conduits have been designed with the goal of regulating and controlling the diffusive transport of molecular, e.g. organic dyes, and ionic species, e.g. AuCl4-, and Cu2+ ions, along predefined 2-D pathways. The transport of these chemical species has been examined by both fluorescence and dark field microscopy. The polymer brushes were formed through microcontact printing of an initiator, followed by surface-initiated Atom Transfer Radical Polymerization (SI-ATRP). SI-ATRP enables both 2-D patterning with a resolution of about 1 micrometer, and control over the resultant polymer brush thickness (which was varied from 10-100 nm). A hydrophilic poly(oligoethylene glycol) acrylate brushe was selected because of its potential to dissolve a wide range of hydrophilic species. The transport of fluorescent species can be directly followed. A non-lithographic fabrication method was developed for mufluidic devices used in the diffusion studies. Singular channel mufluidic device was utilized to study the directed organic dye diffusion. The AuCl4-, and Cu 2+ ion transport was studied by designing molecular devices with two mufluidic channels. We have demonstrated that the various species of interest diffuse much more rapidly along the predefined pathway than along the bare (polymer brush free) regions of the substrate, demonstrating that diffusive conduits for molecular transport can indeed be formed. The protein resistance of poly(N-isopropylacrylamide) (PNIPAM) brushes grafted from silicon wafers was investigated as a function of the chain molecular weight, grafting density, and temperature. Above the lower critical solution temperature (LCST) of 32°C, the collapse of the water swollen chains, determined by

  10. Squaraine-Based Polymer Dots with Narrow, Bright Near-Infrared Fluorescence for Biological Applications

    PubMed Central

    2015-01-01

    This article describes the design and development of squaraine-based semiconducting polymer dots (Pdots) that show large Stokes shifts and narrow-band emissions in the near-infrared (NIR) region. Fluorescent copolymers containing fluorene and squaraine units were synthesized and used as precursors for preparing the Pdots, where exciton diffusion and likely through-bond energy transfer led to highly bright and narrow-band NIR emissions. The resulting Pdots exhibit the emission full width at half-maximum of ∼36 nm, which is ∼2 times narrower than those of inorganic quantum dots in the same wavelength region (∼66 nm for Qdot705). The squaraine-based Pdots show a high fluorescence quantum yield (QY) of 0.30 and a large Stokes shift of ∼340 nm. Single-particle analysis indicates that the average per-particle brightness of the Pdots is ∼6 times higher than that of Qdot705. We demonstrate bioconjugation of the squaraine Pdots and employ the Pdot bioconjugates in flow cytometry and cellular imaging applications. Our results suggest that the narrow bandwidth, high QY, and large Stokes shift are promising for multiplexed biological detections. PMID:25494172

  11. Antioxidant, antimicrobial, cell viability and enzymatic inhibitory of antioxidant polymers as biological macromolecules.

    PubMed

    Hashemi Gahruie, Hadi; Niakousari, Mehrdad

    2017-11-01

    Polymeric antioxidants such as Catechinaldehyde Polycondensates, Catechin-acelaldehydepolycondensates, Flavonoid-grafted chitosan fibers, Ferulate hydrogel, Dextran ferulate hydrogel, Starch-quercetin conjugate, Gallic acid- and Caffeic acid-functionalized chitosan, Gallic acid - chitosan conjugate, Poly(rutin), Gallic acid grafted chitosan, Dextran-Catechin Conjugate belong to biological macromolecules. These kinds of compounds have stronger antioxidant potential and pharmacokinetic activities, as compared to similar low molecular weight preservatives. Most of these compounds sources are either antioxidants with low molecules polymerization, or polymers conjugation such as synthetic or natural preservatives. Additives are well known as being an important ingredient of food products due to their strong preservative potential. Many researchers and industries attempt to find synthesize materials with the same antioxidant potential and higher stability than the similar compounds with low molecular weight. Recently, macromolecular antioxidants have received wide attention as food additives and dietary supplements in functional foods. It seems that the main usage of these compounds is in the food packaging industry. Most of these compounds have strong antioxidant, antimicrobial, cell viability and enzymatic inhibitory properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Constitutional Conservatism

    ERIC Educational Resources Information Center

    Berkowitz, Peter

    2009-01-01

    After their dismal performance in election 2008, conservatives are taking stock. As they examine the causes that have driven them into the political wilderness and as they explore paths out, they should also take heart. After all, election 2008 shows that America's constitutional order is working as designed. Indeed, while sorting out their errors…

  13. Determination of haloperidol in biological samples using molecular imprinted polymer nanoparticles followed by HPLC-DAD detection.

    PubMed

    Ebrahimzadeh, Homeira; Dehghani, Zahra; Asgharinezhad, Ali Akbar; Shekari, Nafiseh; Molaei, Karam

    2013-09-10

    In this study an extraction procedure using molecular imprinted polymer nanoparticles for the determination of haloperidol in biological samples is proposed. The haloperidol imprinted polymer nanoparticles were synthesized successfully by precipitation polymerization in a flask containing haloperidol as a template, ethyleneglycoldimethacrylate as a crosslinking agent, methacrylic acid as a functional monomer, and 2,2'-azobisisobutyronitrile as an initiator. The leached and unleached polymer nanoparticles have been characterized by infrared spectroscopy and scanning electron microscopy. The effect of different variables such as the pH of solution, uptake and elution time, type, and the least amount of eluent for elution of haloperidol from polymer was evaluated. Extraction efficiencies more than 97% were obtained by elution of the polymer with 1.5 mL of methanol-acetic acid-trifluoroacetic acid 79.9:20:0.1. Under optimal conditions maximum adsorption capacity was obtained 153.84 mg g(-1). The detection limit of the proposed procedure was between 0.2 and 0.35 μg L(-1). Finally this method was applied to the determination of haloperidol in plasma and urine samples and satisfactory results were achieved (RSD<6.9%).

  14. Impact of HydroPolymers on the soil biological components in mediterranean drylands

    NASA Astrophysics Data System (ADS)

    Dvořáčková, Helena; Hueso González, Paloma; Záhora, Jaroslav; Mikajlo, Irina; Damián Ruiz Sinoga, Jose

    2016-04-01

    Soil degradation affects more than 52 million ha of land in counties of the European Union. This problem is particularly serious in Mediterranean areas, where the effects of anthropogenic activities (tillage on slopes, deforestation, and pasture production) add to problems caused by prolonged periods of drought and intense and irregular rainfall. Soil microbiota can be used as an indicator of the soil healthy in degraded areas. This is because soil microbiota participates in the cycle elements and in the organic matter decomposition. All this helps to the young plants establishment and in long term protect the soils against the erosion. During dry periods in the Mediterranean areas, the lack of water entering the soil matrix leads to a loss of soil microbiological activity and it turns into a lower soil production capabilities. Under these conditions, the aim of this study was to evaluate the positive effect on soil biological components produced by an hydro absorbent polymer (Terracottem). The aim of the experiment was to evaluate the impact assessment of an hydropolymer (Terracottem) on the soil biological components. An experimental flowerpot layout was established in June 2015 and 12 variants with different amount of Terracottem were applied as follow: i) 3.0 kg.m3 ; ii) 1.5 kg.m3 and; iii) 0 kg.m3. In all the variants were tested the further additives: a) 1% of glucose, b) 50 kg N.ha-1 of Mineral nitrogen, c) 1% of Glucose + 50 kg N.ha-1 of Mineral nitrogen d) control (no additive). According to natural conditions, humidity have been kept at 15% in all the variants. During four weeks, mineral nitrogen leaching and soil respiration have been measured in each flowerplot. Respiration has been quantified four times every time while moistening containers and alkaline soda lime has been used as a sorbent. The amount of CO2 increase has been measured with the sorbent. Leaching of mineral nitrogen has been quantified by ion exchange resins (IER). IER pouches have been

  15. Biodegradable Polymers

    PubMed Central

    Vroman, Isabelle; Tighzert, Lan

    2009-01-01

    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. 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.

  16. Synthesis, Characterization and Biological Studies of New Linear Thermally Stable Schiff Base Polymers with Flexible Spacers.

    PubMed

    Qureshi, Farah; Khuhawar, Muhammad Yar; Jahangir, Taj Muhammad; Channar, Abdul Hamid

    2016-01-01

    Five new linear Schiff base polymers having azomethine structures, ether linkages and extended aliphatic chain lengths with flexible spacers were synthesized by polycondensation of dialdehyde (monomer) with aliphatic and aromatic diamines. The formation yields of monomer and polymers were obtained within 75-92%. The polymers with flexible spacers of n-hexane were somewhat soluble in acetone, chloroform, THF, DMF and DMSO on heating. The monomer and polymers were characterized by melting point, elemental microanalysis, FT-IR, (1)HNMR, UV-Vis spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), fluorescence emission, scanning electron microscopy (SEM) and viscosities and thermodynamic parameters measurements of their dilute solutions. The studies supported formation of the monomer and polymers and on the basis of these studies their structures have been assigned. The synthesized polymers were tested for their antibacterial and antifungal activities.

  17. Hybrid rigid/soft and biologic/synthetic materials: polymers grafted onto cellulose microcrystals.

    PubMed

    Harrisson, Simon; Drisko, Glenna L; Malmström, Eva; Hult, Anders; Wooley, Karen L

    2011-04-11

    Rigid nanoscale polymer rods were prepared by grafting preformed amine-terminated poly(styrene) and poly(tert-butyl acrylate) onto oxidized cellulose microcrystals. Low polydispersity polymers, grown using atom transfer radical polymerization, were characterized and purified prior to cellulose attachment. Oxidation of the cellulose microcrystal led to the formation of carboxylic acids on the surface of the microcrystals. Covalent attachment of the polymers onto the cellulose microcrystals was achieved via a carbodiimide-mediated amidation reaction. The length and diameter of the polymer-cellulose composites increased upon surface modification. Typically, polymer-cellulose composites are synthesized by a grafting-from method because it can be difficult to obtain sufficient graft density using a grafting-to preparation. However, the composites reported here comprised 60-64% grafted polymer by mass. This degree of grafting-to allowed the composite to form stable suspensions in organic solvents.

  18. Cell compatible arginine containing cationic polymer: one-pot synthesis and preliminary biological assessment.

    PubMed

    Zavradashvili, Nino; Memanishvili, Tamar; Kupatadze, Nino; Baldi, Lucia; Shen, Xiao; Tugushi, David; Wandrey, Christine; Katsarava, Ramaz

    2014-01-01

    Synthetic cationic polymers are of interest as both nonviral vectors for intracellular gene delivery and antimicrobial agents. For both applications synthetic polymers containing guanidine groups are of special interest since such kind of organic compounds/polymers show a high transfection potential along with antibacterial activity. It is important that the delocalization of the positive charge of the cationic group in guanidine significantly decreases the toxicity compared to the ammonium functionality. One of the most convenient ways for incorporating guanidine groups is the synthesis of polymers composed of the amino acid arginine (Arg) via either application of Arg-based monomers or chemical modification of polymers with derivatives of Arg. It is also important to have biodegradable cationic polymers that will be cleared from the body after their function as transfection or antimicrobial agent is fulfilled. This chapter deals with a two-step/one-pot synthesis of a new biodegradable cationic polymer-poly(ethylene malamide) containing L-arginine methyl ester covalently attached to the macrochains in β-position of the malamide residue via the α-amino group. The goal cationic polymer was synthesized by in situ interaction of arginine methyl ester dihydrochloride with intermediary poly(ethylene epoxy succinimide) formed by polycondensation of di-p-nitrophenyl-trans-epoxy succinate with ethylenediamine. The cell compatibility study with Chinese hamster ovary (CHO) and insect Schneider 2 cells (S2) within the concentration range of 0.02-500 mg/mL revealed that the new polymer is not cytotoxic. It formed nanocomplexes with pDNA (120-180 nm in size) at low polymer/DNA weight ratios (WR = 5-10). A preliminarily transfection efficiency of the Arg-containing new cationic polymer was assessed using CHO, S2, H5, and Sf9 cells.

  19. Additives-biological activities of tin-containing polymers bonded to noncarbons

    SciTech Connect

    Carraher, C.; Butler, C.; Foster, V.; Pandya, B.; Sterling, D.

    1993-12-31

    Organotin-containing polymers serve as effective additives to a silicon-based sealant, latex coating and talc exhibiting inhibition to tested bacteria and fungi. These polymers are candidates for uses a paint additives, sealant and caulk additives and within talc as an epidermal treatment.

  20. Hydroxyapatite porous scaffold engineered with biological polymer hybrid coating for antibiotic Vancomycin release.

    PubMed

    Kim, Hae-Won; Knowles, Jonathan C; Kim, Hyoun-Ee

    2005-03-01

    The purpose of this study is to improve hydroxyapatite (HA) porous scaffolds via coating with biological polymer-HA hybrids for use as wound healing and tissue regeneration. Highly porous HA scaffolds, fabricated by a polyurethane foam reticulate method, were coated with hybrid coating solution, consisting of poly(epsilon-caprolactone) (PCL), HA powders, and the antibiotic Vancomycin. The PCL to HA ratio was fixed at 1.5 and the drug amounts were varied [drug/(PCL + HA) = 0.02 and 0.04]. For the purpose of comparison, bare HA scaffold without the hybrid coating layer was also loaded with Vancomycin via an immersion-adsorption method. The hybrid coating structure and morphology were observed with Fourier transformed infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The effects of the hybrid coating on the compressive mechanical properties and the in vitro drug release of the scaffolds were investigated in comparison with bare HA scaffold. The PCL-HA hybrid coating altered the scaffold pore structure slightly, resulting in thicker stems and reduced porosity. With the hybrid coating, the HA scaffold responded to an applied compressive stress more effectively without showing a brittle failure. This was attributed to the shielding and covering of the framework surface by the coating layer. The encapsulated drugs within the coated scaffold was released in a highly sustained manner as compared to the rapid release of drugs directly adsorbed on the pure HA scaffold. These findings suggest that the coated HA scaffolds expand their applicability in hard tissue regeneration and wound healing substitutes delivering bioactive molecules.

  1. Chemical and ultrastructural evidence that waxes associated with the suberin polymer constitute the major diffusion barrier to water vapor in potato tuber (Solanum tuberosum L.).

    PubMed

    Soliday, C L; Kolattukudy, P E; Davis, R W

    1979-10-01

    Combined gas chromatography-mass spectrometry showed that C21, C23, and C25 n-alkanes accumulated in the suberized layers during wound healing of cores of potato tuber tissue. Treatment (10 min) of freshly-cut tissue with trichloroacetate (TCA), an inhibitor of fatty-acid chain elongation, severely inhibited accumulation of hydrocarbons and fatty alcohols associated with the suberized layer in the wound healing tissue (maximum inhibition at 4 mM) but had very little effect on the deposition of the major aliphatic components of the suberin polymer. This preferential inhibition of wax synthesis resulted in severe inhibition of the development of diffusion resistance of the tissue to water vapor. These results strongly indicate that the waxes associated with the suberin polymer, rather than the polymer itself, consitute the major diffusion barrier formed during wound healing. Electron-microscopic examination showed that inhibition of wax synthesis by TCA disrupted the formation of the lamellar structure of suberin specifically by preventing the formation of the light bands. This evidence strongly suggests that the light bands in the suberin complex are composed of waxes.

  2. Design of a multi-dopamine-modified polymer ligand optimally suited for interfacing magnetic nanoparticles with biological systems.

    PubMed

    Wang, Wentao; Ji, Xin; Na, Hyon Bin; Safi, Malak; Smith, Alexandra; Palui, Goutam; Perez, J Manuel; Mattoussi, Hedi

    2014-06-03

    We have designed a set of multifunctional and multicoordinating polymer ligands that are optimally suited for surface functionalizing iron oxide and potentially other magnetic nanoparticles (NPs) and promoting their integration into biological systems. The amphiphilic polymers are prepared by coupling (via nucleophilic addition) several amine-terminated dopamine anchoring groups, poly(ethylene glycol) moieties, and reactive groups onto a poly(isobutylene-alt-maleic anhydride) (PIMA) chain. This design greatly benefits from the highly efficient and reagent-free one-step reaction of maleic anhydride groups with amine-containing molecules. The availability of several dopamine groups in the same ligand greatly enhances the ligand affinity, via multiple coordination, to the magnetic NPs, while the hydrophilic and reactive groups promote colloidal stability in buffer media and allow subsequent conjugation with target biomolecules. Iron oxide nanoparticles ligand exchanged with these polymer ligands have a compact hydrodynamic size and exhibit enhanced long-term colloidal stability over the pH range of 4-12 and in the presence of excess electrolytes. Nanoparticles ligated with terminally reactive polymers have been easily coupled to target dyes and tested in live cell imaging with no measurable cytotoxicity. Finally, the resulting hydrophilic nanoparticles exhibit large and size-dependent r2 relaxivity values.

  3. WILL FLUOROTELOMER ALCOHOL BASED POLYMER FORMULATIONS BIODEGRADE DURING AEROBIC BIOLOGICAL WASTEWATER TREATMENT?

    EPA Science Inventory

    The release of fluorotelomer alcohol (FTOH) based polymer formulations (PFs) to wastewater treatment plants (WWTPs) may be an important source of the perfluoroalkyl carboxylic acids (PFCAs) observed in many environmental matrices. Working with the Office of Pollution, Prevention,...

  4. Exploiting the Physicochemical Properties of Dendritic Polymers for Environmental and Biological Applications

    SciTech Connect

    Bhattacharya, Priyanka; Geitner, Nicholas K.; Sarupria, Sapna; Ke, Pu Chun

    2013-04-07

    In this Perspective we first examine the rich physicochemical properties of dendritic polymers for hosting cations, anions, and polyaromatic hydrocarbons. We then extrapolate these conceptual discussions to the use of dendritic polymers for humic acid antifouling, oil dispersion, copper sensing, and fullerenol remediation. In addition, we review the state-of-the-art of dendrimer research and elaborate on their 10 implications for water purification, environmental remediation, nanomedicine, and energy harvesting.

  5. Graphene-polymer hybrid nanostructure-based bioenergy storage device for real-time control of biological motor activity.

    PubMed

    Byun, Kyung-Eun; Choi, Dong Shin; Kim, Eunji; Seo, David H; Yang, Heejun; Seo, Sunae; Hong, Seunghun

    2011-11-22

    We report a graphene-polymer hybrid nanostructure-based bioenergy storage device to turn on and off biomotor activity in real-time. In this strategy, graphene was functionalized with amine groups and utilized as a transparent electrode supporting the motility of biomotors. Conducting polymer patterns doped with adenosine triphosphate (ATP) were fabricated on the graphene and utilized for the fast release of ATP by electrical stimuli through the graphene. The controlled release of biomotor fuel, ATP, allowed us to control the actin filament transportation propelled by the biomotor in real-time. This strategy should enable the integrated nanodevices for the real-time control of biological motors, which can be a significant stepping stone toward hybrid nanomechanical systems based on motor proteins. © 2011 American Chemical Society

  6. Biological materials: (Part A): Temperature-responsive polymers and drug delivery, and, (Part B): Polymer modification of fish scale and their nano-mechanical properties

    NASA Astrophysics Data System (ADS)

    Xiang, Xu

    This research has three parts. Two parts deal with novel nanoparticle assemblies for drug delivery, and are described in Part A, while the third part looks at properties of fish scales, an abundant and little-used waste resource, that can be modified to have value in medical and other areas. Part A describes fundamental research into the affects of block sequence of amphiphilic block copolymers prepared from on a new and versatile class of monomers, oligo(ethylene glycol) methyl ether acrylate (OEGA) and the more hydrophobic di(ethylene glycol) methyl ether methacrylate (DEGMA). Polymers from these monomers are biologically safe and give polymers with thermoresponsive properties that can be manipulated over a broader temperature range than the more researched N-isopropylacrylamide polymers. Using RAFT polymerization and different Chain Transfer Agents (CTAs) amphiphilic block copolymers were prepared to study the effect of block sequence (hydrophilic OEGA and more hydrophobic DEGMA) on their thermo-responsive properties. Pairing hydrophilic chain ends to a hydrophobic DEGMA block and hydrophobic chain ends to hydrophilic blocks ("mis-matched polarity") significantly affected thermoresponsive properties for linear and star diblock copolymers, but little affected symmetric triblock copolymers. Specifically matching polarity in diblock copolymers yielded nanoparticles with higher cloud points (CP), narrow temperature ranges for coil collapse above CP, and smaller hydrodynamic diameter than mis-matched polarity. Using this knowledge two linear OEGA/DEGMA diblock copolymers were prepared with thiol end groups and assembled into hybrid nanoparticles with a gold nanoparticle core (GNP-polymer hybrids). This design was made using the hypothesis that a hybrid polymer drug carrier with a high CP (50-60 °C) and a diblock structure could be designed with low levels of drug release below 37 °C (body temperature) allowing the drug carrier to reach a target (tumor) site with

  7. Anomalous Diffusion in Polymer Solution as Probed by Fluorescence Correlation Spectroscopy and Its Universal Importance in Biological Systems

    NASA Astrophysics Data System (ADS)

    Ushida, Kiminori

    2008-02-01

    Experimental evidence of anomalous diffusion occurring in an inhomogeneous media (hyaluronan aquous solution) was obtained by use of fluorescence correlation spectroscopy (FCS) combined with other techniques (PFG-NMR and Photochemical reactions). The diffusion coefficient was obtained as a function of diffusion time or diffusion distance. Since this polymer solution can be regarded as a model system of extracellular matrices (ECMs), intercellular communication, which takes part in ECM, is greatly influenced by this anomalous diffusion mode. Therefore universal importance of anomalous diffusion in biological activity is identified in this series of independent experiments to measure diffusion coefficients.

  8. Well-defined hydrophilic molecularly imprinted polymer microspheres for efficient molecular recognition in real biological samples by facile RAFT coupling chemistry.

    PubMed

    Zhao, Man; Chen, Xiaojing; Zhang, Hongtao; Yan, Husheng; Zhang, Huiqi

    2014-05-12

    A facile and highly efficient new approach (namely RAFT coupling chemistry) to obtain well-defined hydrophilic molecularly imprinted polymer (MIP) microspheres with excellent specific recognition ability toward small organic analytes in the real, undiluted biological samples is described. It involves the first synthesis of "living" MIP microspheres with surface-bound vinyl and dithioester groups via RAFT precipitation polymerization (RAFTPP) and their subsequent grafting of hydrophilic polymer brushes by the simple coupling reaction of hydrophilic macro-RAFT agents (i.e., hydrophilic polymers with a dithioester end group) with vinyl groups on the "living" MIP particles in the presence of a free radical initiator. The successful grafting of hydrophilic polymer brushes onto the obtained MIP particles was confirmed by SEM, FT-IR, static contact angle and water dispersion studies, elemental analyses, and template binding experiments. Well-defined MIP particles with densely grafted hydrophilic polymer brushes (∼1.8 chains/nm(2)) of desired chemical structures and molecular weights were readily obtained, which showed significantly improved surface hydrophilicity and could thus function properly in real biological media. The origin of the high grafting densities of the polymer brushes was clarified and the general applicability of the strategy was demonstrated. In particular, the well-defined characteristics of the resulting hydrophilic MIP particles allowed the first systematic study on the effects of various structural parameters of the grafted hydrophilic polymer brushes on their water-compatibility, which is of great importance for rationally designing more advanced real biological sample-compatible MIPs.

  9. Polymer Fluid Dynamics.

    ERIC Educational Resources Information Center

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  10. Polymer Fluid Dynamics.

    ERIC Educational Resources Information Center

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  11. Molecular dynamics modeling the synthetic and biological polymers interactions pre-studied via docking

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Vladimir B.; Serbin, Alexander V.

    2014-06-01

    In previous works we reported the design, synthesis and in vitro evaluations of synthetic anionic polymers modified by alicyclic pendant groups (hydrophobic anchors), as a novel class of inhibitors of the human immunodeficiency virus type 1 ( HIV-1) entry into human cells. Recently, these synthetic polymers interactions with key mediator of HIV-1 entry-fusion, the tri-helix core of the first heptad repeat regions [ HR1]3 of viral envelope protein gp41, were pre-studied via docking in terms of newly formulated algorithm for stepwise approximation from fragments of polymeric backbone and side-group models toward real polymeric chains. In the present article the docking results were verified under molecular dynamics ( MD) modeling. In contrast with limited capabilities of the docking, the MD allowed of using much more large models of the polymeric ligands, considering flexibility of both ligand and target simultaneously. Among the synthesized polymers the dinorbornen anchors containing alternating copolymers of maleic acid were selected as the most representative ligands (possessing the top anti-HIV activity in vitro in correlation with the highest binding energy in the docking). To verify the probability of binding of the polymers with the [HR1]3 in the sites defined via docking, various starting positions of polymer chains were tried. The MD simulations confirmed the main docking-predicted priority for binding sites, and possibilities for axial and belting modes of the ligands-target interactions. Some newly MD-discovered aspects of the ligand's backbone and anchor units dynamic cooperation in binding the viral target clarify mechanisms of the synthetic polymers anti-HIV activity and drug resistance prevention.

  12. Extension of in vivo half-life of biologically active peptides via chemical conjugation to XTEN protein polymer.

    PubMed

    Podust, Vladimir N; Sim, Bee-Cheng; Kothari, Dharti; Henthorn, Lana; Gu, Chen; Wang, Chia-wei; McLaughlin, Bryant; Schellenberger, Volker

    2013-11-01

    XTEN, unstructured biodegradable proteins, have been used to extend the in vivo half-life of genetically fused therapeutic proteins and peptides. To expand the applications of XTEN technology to half-life extension of other classes of molecules, XTEN protein polymers and methods for chemical XTENylation were developed. Two XTEN precursors were engineered to contain enzymatically removable purification tags. The proteins were readily expressed in bacteria and purified to homogeneity by chromatography techniques. As proof-of-principle, GLP2-2G peptide was chemically conjugated to each of the two XTEN protein polymers using maleimide-thiol chemistry. The monodisperse nature of XTEN protein polymer enabled reaction monitoring as well as the detection of peptide modifications in the conjugated state using reverse phase-high performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry. The resulting GLP2-2G-XTEN conjugates were purified by preparative RP-HPLC to homogeneity. In comparison with recombinantly fused GLP2-2G-XTEN, chemically conjugated GLP2-2G-XTEN molecules exhibited comparable in vitro activity, in vitro plasma stability and pharmacokinetics in rats. These data suggest that chemical XTENylation could effectively extend the half-life of a wide spectrum of biologically active molecules, therefore broadening its applicability.

  13. Biological and protein-binding studies of newly synthesized polymer-cobalt(III) complexes.

    PubMed

    Vignesh, G; Pradeep, I; Arunachalam, S; Vignesh, S; Arthur James, R; Arun, R; Premkumar, K

    2016-03-01

    The polymer-cobalt(III) complexes, [Co(bpy)(dien)BPEI]Cl3 · 4H2O (bpy = 2,2'-bipyridine, dien = diethylentriamine, BPEI = branched polyethyleneimine) were synthesized and characterized. The interaction of these complexes with human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under physiological conditions using various physico-chemical techniques. The results reveal that the fluorescence quenching of serum albumins by polymer-cobalt(III) complexes took place through static quenching. The binding of these complexes changed the molecular conformation of the protein considerably. The polymer-cobalt(III) complex with x = 0.365 shows antimicrobial activity against several human pathogens. This complex also induces cytotoxicity against MCF-7 through apoptotic induction. However, further studies are needed to decipher the molecular mode of action of polymer-cobalt(III) complex and for its possible utilization in anticancer therapy. Copyright © 2015 John Wiley & Sons, Ltd.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  16. Novel transducers for nano-optical biosensor chips based on biological and synthetic polymers with analyte-dependent swelling/shrinking behavior.

    PubMed

    Lepek, M; Pittner, F

    2004-01-01

    Analyte-dependent swelling/shrinking properties of ultrathin polymer layers are an appropriate means for the detection of various analytes. Optical metal nanoclusters can be used to determine the change of the layer's thickness, which is shown by a change in the color of the chip. By using different cross-linking agents and different polymers (biological or artificial as well) it was possible to design various sensitive layers showing different swelling/shrinking behaviors. Sensitivity on various analytes could be observed, since the different types of polymers employed differed in structure, functional groups, or biorecognitive properties.

  17. Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications

    PubMed Central

    Schneider, Hans-Jörg; Kato, Kazuaki; Strongin, Robert M.

    2007-01-01

    Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a selective response by automatically triggered size changes. This is illustrated with non-covalent interactions of effectors comprising of metal ions, isomeric organic compounds, including enantiomers, nucleotides, aminoacids, and peptides. Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate. This concept is particularly fruitful with effector compounds such as peptides, which only trigger size changes if, e.g. copper ions are present in the surroundings. Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer. The most promising application is the selective interaction of covalently fixed boronic acid residues with glucose, which renders itself not only for sensing, but eventually also for delivery of drugs such as insulin. The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles. Of particular interest is the sensitivity increase which can be reached by downsizing the particle volume. PMID:19606275

  18. What Is a Constitution?

    ERIC Educational Resources Information Center

    OAH Magazine of History, 1988

    1988-01-01

    Provides a lesson plan designed to help students better understand the concept of a constitution, distinguish constitutional law from statutory law, and recognize examples of constitutional government. (BSR)

  19. Biological and physicochemical properties of carbon-graphite fibre-reinforced polymers intended for implant suprastructures.

    PubMed

    Segerström, Susanna; Sandborgh-Englund, Gunilla; Ruyter, Eystein I

    2011-06-01

    The aim of this study was to determine water sorption, water solubility, dimensional change caused by water storage, residual monomers, and possible cytotoxic effects of heat-polymerized carbon-graphite fibre-reinforced composites with different fibre loadings based on methyl methacrylate/poly(methyl methacrylate) (MMA/PMMA) and the copolymer poly (vinyl chloride-co-vinyl acetate). Two different resin systems were used. Resin A contained ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (1,4-BDMA); the cross-linker in Resin B was diethylene glycol dimethacrylate (DEGDMA). The resin mixtures were reinforced with 24, 36 and 47 wt% surface-treated carbon-graphite fibres. In addition, polymer B was reinforced with 58 wt% fibres. Water sorption was equal to or below 3.34±1.18 wt%, except for the 58 wt% fibre loading of polymer B (5.27±1.22 wt%). Water solubility was below 0.36±0.015 wt%, except for polymer B with 47 and 58 wt% fibres. For all composites, the volumetric increase was below 0.01±0.005 vol%. Residual MMA monomer was equal to or below 0.68±0.05 wt% for the fibre composites. The filter diffusion test and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay demonstrated no cytotoxicity for the carbon-graphite fibre-reinforced composites, and residual cross-linking agents and vinyl chloride were not detectable by high-performance liquid chromatography (HPLC) analysis.

  20. Biomaterials-Based Electronics: Polymers and Interfaces for Biology and Medicine

    PubMed Central

    Muskovich, Meredith; Bettinger, Christopher J.

    2012-01-01

    Advanced polymeric biomaterials continue to serve as a cornerstone of new medical technologies and therapies. The vast majority of these materials, both natural and synthetic, interact with biological matter without direct electronic communication. However, biological systems have evolved to synthesize and employ naturally-derived materials for the generation and modulation of electrical potentials, voltage gradients, and ion flows. Bioelectric phenomena can be interpreted as potent signaling cues for intra- and inter-cellular communication. These cues can serve as a gateway to link synthetic devices with biological systems. This progress report will provide an update on advances in the application of electronically active biomaterials for use in organic electronics and bio-interfaces. Specific focus will be granted to the use of natural and synthetic biological materials as integral components in technologies such as thin film electronics, in vitro cell culture models, and implantable medical devices. Future perspectives and emerging challenges will also be highlighted. PMID:23184740

  1. Biomaterials-based electronics: polymers and interfaces for biology and medicine.

    PubMed

    Muskovich, Meredith; Bettinger, Christopher J

    2012-05-01

    Advanced polymeric biomaterials continue to serve as a cornerstone for new medical technologies and therapies. The vast majority of these materials, both natural and synthetic, interact with biological matter in the absence of direct electronic communication. However, biological systems have evolved to synthesize and utilize naturally-derived materials for the generation and modulation of electrical potentials, voltage gradients, and ion flows. Bioelectric phenomena can be translated into potent signaling cues for intra- and inter-cellular communication. These cues can serve as a gateway to link synthetic devices with biological systems. This progress report will provide an update on advances in the application of electronically active biomaterials for use in organic electronics and bio-interfaces. Specific focus will be granted to covering technologies where natural and synthetic biological materials serve as integral components such as thin film electronics, in vitro cell culture models, and implantable medical devices. Future perspectives and emerging challenges will also be highlighted.

  2. Development of Voltammetric Double-Polymer-Modified Electrodes for Nanomolar Ion Detection for Environmental and Biological Applications

    NASA Astrophysics Data System (ADS)

    Kim, Yushin

    Qualitative and quantitative electrochemical methods for trace ion analysis of organic and inorganic species with environmental and biological attention have been developed and reported during past decades. The development of fast and accurate electrochemical methods is critical for field applications with various blocking contaminants. Voltammetric method is attractive not only to analyze selective ion species due to its characteristic based on ion lipophilicity, but also to lower the limit of detection by combining with stripping analysis. In my PhD work, I have developed and studied a highly selective and sensitive electrochemical method that can be used to characterize fundamental transport dynamics and to develop electrochemical sensors at liquid/liquid interfaces based on electrochemically-controlled ion transfer and recognition. The understanding of the kinetic and thermodynamic properties of the voltammetric ion transfer through polymer-modified ion-selective electrodes leads to realize the highly selective and sensitive analytical method. The ultrathin polymer membrane is used to maximize a current response by complete exhaustion of preconcentrated ions. Therefore, nanomolar detection is achieved and confirmed by a thermodynamic mechanism that controls the detection limit. It was also demonstrated experimentally and theoretically that more lipophilic ionic species gives a significantly lower detection limit. The voltammetric method was expanded into inexpensive and disposable applications based on pencil lead modified with the thin polymer membrane. In the other hand, micropipet/nanopipet voltammetry as an artificial cell membrane was used to study the interface between two immiscible solutions for environmental and biomedical applications. It is very useful to get quantitative kinetic and thermodynamic information by studying numerical simulations of ion transfer and diffusion. Molecular recognition and transport of heparin and low

  3. Creating Biological Membranes on the Micron Scale: Forming Patterned Lipid Bilayers Using a Polymer Lift-Off Technique

    PubMed Central

    Orth, R. N.; Kameoka, J.; Zipfel, W. R.; Ilic, B.; Webb, W. W.; Clark, T. G.; Craighead, H. G.

    2003-01-01

    We present a new method for creating patches of fluid lipid bilayers with conjugated biotin and other compounds down to 1 μm resolution using a photolithographically patterned polymer lift-off technique. The patterns are realized as the polymer is mechanically peeled away in one contiguous piece in solution. The functionality of these surfaces is verified with binding of antibodies and avidin on these uniform micron-scale platforms. The biomaterial patches, measuring 1 μm–76 μm on edge, provide a synthetic biological substrate for biochemical analysis that is ∼100× smaller in width than commercial printing technologies. 100 nm unilamellar lipid vesicles spread to form a supported fluid lipid bilayer on oxidized silicon surface as confirmed by fluorescence photobleaching recovery. Fluorescence photobleaching recovery measurements of DiI (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiIC18(3))) stained bilayer patches yielded an average diffusion coefficient of 7.54 ± 1.25 μm2 s−1, equal to or slightly faster than typically found in DiI stained cells. This diffusion rate is ∼3× faster than previous values for bilayers on glass. This method provides a new means to form functionalized fluid lipid bilayers as micron-scale platforms to immobilize biomaterials, capture antibodies and biotinylated reagents from solution, and form antigenic stimuli for cell stimulation. PMID:14581207

  4. Preparation of 17β-estradiol surface molecularly imprinted polymers and their application to the analysis of biological samples.

    PubMed

    Zhang, Jing; Wang, Lingling; Han, Yanting

    2013-11-01

    17β-Estradiol (E2) surface molecularly imprinted polymers have been prepared using functionalized monodispersed poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads as a support. The resulting polymers were found to be uniform in size (5 μm), and the surfaces of the microspheres possessed large pore-like structures. A chromatographic experiment demonstrated that the resulting microspheres exhibited high levels of recognition and selectivity toward the target molecule. The particles were employed as a novel sorbent in a molecularly imprinted SPE protocol. A method was then developed involving the combination of the pretreatment with HPLC to determine the levels of estrogen secreted from Michigan Cancer Foundation-7 cells. The obtained results revealed that the extraction recoveries of E2 from real samples were in the range of 73.0-97.5% with RSDs of < 7.5% (n = 3). Calibration curves were established with R values > 0.9996 for concentrations in the range of 0.50-100.00 ng/mL. The LOD of this new method was 0.14 ng/mL. Compared with traditional C18 SPE agents, the particles showed high selectivity and extraction efficiency for E2 in the pretreatment process. The particles could therefore be used to determine trace estrogen in biological samples with a UV detector only.

  5. Creating biological membranes on the micron scale: forming patterned lipid bilayers using a polymer lift-off technique.

    PubMed

    Orth, R N; Kameoka, J; Zipfel, W R; Ilic, B; Webb, W W; Clark, T G; Craighead, H G

    2003-11-01

    We present a new method for creating patches of fluid lipid bilayers with conjugated biotin and other compounds down to 1 microm resolution using a photolithographically patterned polymer lift-off technique. The patterns are realized as the polymer is mechanically peeled away in one contiguous piece in solution. The functionality of these surfaces is verified with binding of antibodies and avidin on these uniform micron-scale platforms. The biomaterial patches, measuring 1 micro m-76 microm on edge, provide a synthetic biological substrate for biochemical analysis that is approximately 100x smaller in width than commercial printing technologies. 100 nm unilamellar lipid vesicles spread to form a supported fluid lipid bilayer on oxidized silicon surface as confirmed by fluorescence photobleaching recovery. Fluorescence photobleaching recovery measurements of DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiIC(18)(3))) stained bilayer patches yielded an average diffusion coefficient of 7.54 +/- 1.25 microm(2) s(-1), equal to or slightly faster than typically found in DiI stained cells. This diffusion rate is approximately 3x faster than previous values for bilayers on glass. This method provides a new means to form functionalized fluid lipid bilayers as micron-scale platforms to immobilize biomaterials, capture antibodies and biotinylated reagents from solution, and form antigenic stimuli for cell stimulation.

  6. Mind your P's and Q's: the coming of age of semiconducting polymer dots and semiconductor quantum dots in biological applications.

    PubMed

    Massey, Melissa; Wu, Miao; Conroy, Erin M; Algar, W Russ

    2015-08-01

    Semiconductor quantum dots (QDs) and semiconducting polymer nanoparticles (Pdots) are brightly emissive materials that offer many advantages for bioanalysis and bioimaging, and are complementary to revolutionary advances in fluorescence technology. Within the context of biological applications, this review compares the evolution and different stages of development of these two types of nanoparticle, and addresses current perceptions about QDs. Although neither material is a wholesale replacement for fluorescent dyes, recent trends have demonstrated that both types of nanoparticle can excel in applications that are often too demanding for fluorescent dyes alone. Examples discussed in this review include single particle tracking and imaging, multicolor imaging and multiplexed detection, biosensing, point-of-care diagnostics, in vivo imaging and drug delivery. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Comparison between polyethylene glycol and zwitterionic polymers as antifouling coatings on wearable devices for selective antigen capture from biological tissue.

    PubMed

    Robinson, Kye J; Coffey, Jacob W; Muller, David A; Young, Paul R; Kendall, Mark A F; Thurecht, Kristofer J; Grøndahl, Lisbeth; Corrie, Simon R

    2015-12-07

    Selective capture of disease-related proteins in complex biological fluids and tissues is an important aim in developing sensitive protein biosensors for in vivo applications. Microprojection arrays are biomedical devices whose mechanical and chemical properties can be tuned to allow efficient penetration of skin, coupled with highly selective biomarker capture from the complex biological environment of skin tissue. Herein, the authors describe an improved surface modification strategy to produce amine-modified polycarbonate arrays, followed by the attachment of an antifouling poly(sulfobetaine-methacrylate) (pSBMA) polymer or a linear polyethylene glycol (PEG) polymer of comparative molecular weight and hydrodynamic radius. Using a "grafting to" approach, pSBMA and linear PEG coatings yielded comparative antifouling behavior in single protein solutions, diluted plasma, or when applied to mouse flank skin penetrating into the vascularized dermal tissue. Interestingly, the density of immobilized immunoglobulin G (IgG) or bovine serum albumin protein on pSBMA surfaces was significantly higher than that on the PEG surfaces, while the nonspecific adsorption was comparable for each protein. When incubated in buffer or plasma solutions containing dengue non-structural protein 1 (NS1), anti-NS1-IgG-coated pSBMA surfaces captured significantly more NS1 in comparison to PEG-coated devices. Similarly, when wearable microprojection arrays were applied to the skin of dengue-infected mice using the same coatings, the pSBMA-coated devices showed significantly higher capture efficiency (>2-fold increase in signal) than the PEG-coated substrates, which showed comparative signal when applied to naïve mice. In conclusion, zwitterionic pSBMA polymers (of equivalent hydrodynamic radii to PEG) allowed detection of dengue NS1 disease biomarker in a preclinical model of dengue infection, showing significantly higher signal-to-noise ratio in comparison to the PEG controls. The results of

  8. Efficient synthesis of narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with excellent molecular recognition ability in a real biological sample.

    PubMed

    Zhao, Man; Zhang, Cong; Zhang, Ying; Guo, Xianzhi; Yan, Husheng; Zhang, Huiqi

    2014-02-28

    A facile and highly efficient approach to obtain narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with molecular recognition ability in a real biological sample as good as what they show in the organic solvent-based media is described for the first time.

  9. Rheological properties of a biological thermo-responsive hydrogel produced from soybean oil polymers

    USDA-ARS?s Scientific Manuscript database

    The rheological properties of a newly developed biological thermo-hydrogel made from vegetable oil were investigated. The material named HPSO-HG is a hydrolytic product of polymerized soybean oil (PSO). HPSO-HG is a thermo-responsive gel, and it exhibited viscoelastic behavior above 2% (wt.%) at roo...

  10. Rheological properties of a biological thermo-responsive hydrogel produced from soybean oil polymers

    USDA-ARS?s Scientific Manuscript database

    The rheological properties of a newly developed biological thermo-hydrogel made from vegetable oil were investigated. The material named HPSO-VI is a hydrolytic product of polymerized soybean oil (PSO). HPSO-VI exhibited viscoelastic behavior above 2% (wt. %) at room temperature and viscous fluid ...

  11. Rheological Properties of a Biological Thermo-Hydrogel Produced from Soybean Oil Polymers

    USDA-ARS?s Scientific Manuscript database

    The rheological properties of a newly developed biological thermo-hydrogel made from vegetable oil were investigated. The material named HPSO-HG is a hydrolytic product of polymerized soybean oil (PSO). HPSO-HG exhibited viscoelastic behavior above 2% (wt.%) at room temperature and viscous fluid b...

  12. Star Polymers.

    PubMed

    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.

  13. Development of a stimuli-responsive polymer nanocomposite toward biologically optimized, MEMS-based neural probes

    NASA Astrophysics Data System (ADS)

    Hess, A. E.; Capadona, J. R.; Shanmuganathan, K.; Hsu, L.; Rowan, S. J.; Weder, C.; Tyler, D. J.; Zorman, C. A.

    2011-05-01

    This paper reports the development of micromachining processes and mechanical evaluation of a stimuli-responsive, mechanically dynamic polymer nanocomposite for biomedical microsystems. This nanocomposite consists of a cellulose nanofiber network encased in a polyvinyl acetate matrix. Micromachined tensile testing structures fabricated from the nanocomposite displayed a reversible and switchable stiffness comparable to bulk samples, with a Young's modulus of 3420 MPa when dry, reducing to ~20 MPa when wet, and a stiff-to-flexible transition time of ~300 s. This mechanically dynamic behavior is particularly attractive for the development of adaptive intracortical probes that are sufficiently stiff to insert into the brain without buckling, but become highly compliant upon insertion. Along these lines, a micromachined neural probe incorporating parylene insulating/moisture barrier layers and Ti/Au electrodes was fabricated from the nanocomposite using a fabrication process designed specifically for this chemical- and temperature-sensitive material. It was found that the parylene layers only slightly increased the stiffness of the probe in the wet state in spite of its much higher Young's modulus. Furthermore, the Ti/Au electrodes exhibited impedance comparable to Au electrodes on conventional substrates. Swelling of the nanocomposite was highly anisotropic favoring the thickness dimension by a factor of 8 to 12, leading to excellent adhesion between the nanocomposite and parylene layers and no discernable deformation of the probes when deployed in deionized water.

  14. Heparin-like synthetic polymers, named RGTAs, mimic biological effects of heparin in vitro.

    PubMed

    Rouet, Vincent; Meddahi-Pellé, Anne; Miao, Hua-Quan; Vlodavsky, Israel; Caruelle, Jean-Pierre; Barritault, Denis

    2006-09-15

    A family of biopolymers engineered to protect and stabilize heparin binding growth factors (HBGFs) show remarkable properties as wound healing agents in several in vivo tissue repair models to the extend that damaged tissues would recover almost its initial aspect and properties. These polymers where named RGTA for regenerating agents and proposed to act in vivo by enhancing the bioavailability of HBGFs at the site of the injury. To provide support for this hypothesis, we studied interaction of RGTA with FGF-2, taken as the paradigm of HBGFs, and its high- and low-affinity receptors as well as its ability to inhibit heparanase activity. We show that RGTA is comparable to heparin as it favors FGF-2 binding to FGFR-1 and FGF-2 dimerization and potentiates FGF-2-induced mitogenic activity. Furthermore, we show that RGTA inhibits the release of FGF-2 from its extracellular matrix storage sites by heparanase. Our data provide new evidence to support that RGTA may act in vivo both by enhancing HBGF activity and preserving HBGF availability by protecting the matrix low affinity heparan sulfates from rapid heparanase degradation. 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

  15. Nanocomposites of iridium oxide and conducting polymers as electroactive phases in biological media.

    PubMed

    Moral-Vico, J; Sánchez-Redondo, S; Lichtenstein, M P; Suñol, C; Casañ-Pastor, N

    2014-05-01

    Much effort is currently devoted to implementing new materials in electrodes that will be used in the central nervous system, either for functional electrostimulation or for tests on nerve regeneration. Their main aim is to improve the charge capacity of the electrodes, while preventing damaging secondary reactions, such as peroxide formation, occurring while applying the electric field. Thus, hybrids may represent a new generation of materials. Two novel hybrid materials are synthesized using three known biocompatible materials tested in the neural system: polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT) and iridium oxide (IrO2). In particular, PPy-IrO2 and PEDOT-IrO2 hybrid nanocomposite materials are prepared by chemical polymerization in hydrothermal conditions, using IrO2 as oxidizing agent. The reaction yields a significant ordered new hybrid where the conducting polymer is formed around the IrO2 nanoparticles, encapsulating them. Scanning electron microscopy and backscattering techniques show the extent of the encapsulation. Both X-ray photoelectron and Fourier transform infrared spectroscopies identify the components of the phases, as well as the absence of impurities. Electrochemical properties of the final phases in powder and pellet form are evaluated by cyclic voltammetry. Biocompatibility is tested with MTT toxicity tests using primary cultures of cortical neurons grown in vitro for 6 and 9days. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Biodegradable polymers derived from amino acids.

    PubMed

    Khan, Wahid; Muthupandian, Saravanan; Farah, Shady; Kumar, Neeraj; Domb, Abraham J

    2011-12-08

    In the past three decades, the use of polymeric materials has increased dramatically for biomedical applications. Many α-amino acids derived biodegradable polymers have also been intensely developed with the main goal to obtain bio-mimicking functional biomaterials. Polymers derived from α-amino acids may offer many advantages, as these polymers: (a) can be modified further to introduce new functions such as imaging, molecular targeting and drugs can be conjugated chemically to these polymers, (b) can improve on better biological properties like cell migration, adhesion and biodegradability, (c) can improve on mechanical and thermal properties and (d) their degradation products are expected to be non-toxic and readily metabolized/excreted from the body. This manuscript focuses on biodegradable polymers derived from natural amino acids, their synthesis, biocompatibility and biomedical applications. It is observed that polymers derived from α-amino acids constitute a promising family of biodegradable materials. These provide innovative multifunctional polymers possessing amino acid side groups with biological activity and with innumerous potential applications.

  17. Molecularly imprinted polymer on a SiO2 -coated graphene oxide surface for the fast and selective dispersive solid-phase extraction of Carbamazepine from biological samples.

    PubMed

    Khalilian, Faezeh; Ahmadian, Setareh

    2016-04-01

    A surface carbamazepine-imprinted polymer was grafted and synthesized on the SiO2 /graphene oxide surface. Firstly SiO2 was coated on synthesized graphene oxide sheet using the sol-gel technique. Prior to polymerization, the vinyl group was incorporated on to the surface of SiO2 /graphene oxide to direct selective polymerization on the surface. Methacrylic acid, ethylene glycol dimethacrylate and ethanol were used as monomer, cross-linker and porogen, respectively. Nonimprinted polymer was also prepared for comparison. The properties of the molecularly imprinted polymer were characterized using field-emission scanning electron microscopy and Fourier-transform infrared spectroscopy. The surface molecularly imprinted polymer was utilized as an adsorbent of dispersive solid-phase extraction for separation and preconcentration of carbamazepine. The effects of the different parameters influencing the extraction efficiency, such as sample pH were investigated and optimized. The specificity of the molecular imprinted polymer over the nonimprinted polymer was examined in absence and presence of competitive drugs. The carbamazepine calibration curve showed linearity in the ranges 0.5-500 μg/L. The limits of detection and quantification under the optimized conditions were 0.1 and 0.3 μg/L, respectively. The within-day and between-day relative standard deviations (n = 3) were 3.6 and 4.3%, respectively. Furthermore, the relative recoveries for spiked biological samples were above 85%.

  18. Versatile method for production and controlled polymer-immobilization of biologically active recombinant proteins.

    PubMed

    Allard, Laure; Cheynet, Valérie; Oriol, Guy; Mandrand, Bernard; Delair, Thierry; Mallet, François

    2002-11-05

    The immobilization of a protein by covalent attachment to a support matrix should involve only functional groups of the protein that are not essential for its biological activity. A general strategy for obtaining recombinant proteins designed for oriented covalent grafting onto copolymers was investigated. The rationale involves the definition of seven p24-derived recombinant proteins as fused to either distant or adjacent tags comprising primary amine rich tag consisting of six contiguous lysines suitable for oriented covalent immobilization and a hexa-histidine tag suitable for metal chelate affinity purification. High-level expression, efficient affinity purification, and coupling yields onto maleic anhydride-alt-methyl vinyl ether copolymers higher than 95% were obtained for all proteins. Afterwards, an investigation of the biological features of the immobilized vs. nonimmobilized protein onto the copolymer allowed us to select one bioconjugate which was used in a diagnostic context, i.e., as a capture antigen in an ELISA format test. Sera from 107 HIV-seropositive individuals at various stages of HIV infection, including two seroconversion panels and 104 healthy HIV-seronegative controls, were tested using either RH24 or RK24H-copolymer coated onto the microtiter plate. These assays showed that the use of such a protein-copolymer bioconjugate allowed detection of lower antibody titers than the RH24 protein, illustrating the potential of applications of such doubly tagged proteins. Thus, a set of expression vectors was designed containing four different combinations of hexa-lysine and hexa-histidine tags and a multiple cloning site, allowing the production of different recombinant fusion proteins suitable for biological reactivity conservation after immobilization. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 341-348, 2002.

  19. Polymer-supported organotin reagent for prosthetic group labeling of biological macromolecules with radioiodine.

    PubMed

    Gifford, Andrew N; Kuschel, Sonja; Shea, Colleen; Fowler, Joanna S

    2011-03-16

    In this study, we investigated the use of poly-mer-bound precursor for generating a radiolabeled prosthetic group to be used for conjugate labeling of biological macromolecules. For the approach, a trialkyltin chloride in which the tin was bound to a hydrophilic PEG-based resin support via one of the alkyl groups was synthesized. This resin was then used to prepare a resin-bound trialkyltin benzoic acid, which in some cases was further derivatized on-resin by converting it to a succinimidyl ester. Exposure of the resin-bound compounds to electrophilic radioiodine (¹²⁵I) in either an aqueous or methanol solvent liberated either free radiolabeled [¹²⁵I]iodobenzoic acid or its succinimidyl ester without co-release of the resin-bound precursors. Radiochemical yield was between 35% and 75%, depending on the solvent system and precursor. As example applications for the released compounds, the amine-reactive N-succinimidyl-[¹²⁵I]iodobenzoate prosthetic group was used for conjugate radiolabeling of a peptide, tomato plant systemin, and two proteins, albumin and IgG antibody. These results demonstrate that resin-bound organotin precursors in which the compound to be labeled is tethered to the support via the tin group to be substituted can be used to produce radioiodine-labeled aromatic prosthetic groups in good specific activity without the need for HPLC purification. This solid-phase approach is potentially adaptable to kit-formulation for performing conjugate radiolabeling of biological macromolecules.

  20. Microcontact printing of novel co-polymers in combination with proteins for cell-biological applications.

    PubMed

    Csucs, Gabor; Michel, Roger; Lussi, Jost W; Textor, Marcus; Danuser, Gaudenz

    2003-05-01

    Microcontact printing (microcP) is a cost effective and simple method to create chemically micropatterned surfaces for cell biological applications. We have combined the technique with the spontaneous molecular assembly of a polycationic PEG-grafted copolymer, poly-L-lysine-g-poly(ethylene glycol) (PLL-g-PEG). PLL-g-PEG with omega-functionalized PEG chains was print-transferred onto tissue culture polystyrene (TCPS) or glass substrates, resulting in patterns with a lateral resolution down to 1 microm. Subsequently, dipping in an aqueous solution of non-functionalized PLL-g-PEG was used to backfill the non-printed regions of the surface, rendering them highly protein and thus cell resistant. In a second approach, proteins were stamped and a PLL-g-PEG backfill was applied for passivation of the bare surface regions. Printing of peptide(RGD)-functionalized PLL-g-PEG or proteins combined with a subsequent PLL-g-PEG backfill can be applied to a wide variety of substrate materials with negatively charged surfaces such as TCPS, glass and many metal oxides. We have tested the printed surfaces with human foreskin fibroblasts for cell adhesion and long-term performance and with fish epidermal keratocytes for cell motility and short-time behaviour. Both cell types reacted selectively to the surface micropatterns. Fibroblasts adhered to the printed (adhesive) regions only, where they remained attached up to at least 1 week and were even able to proliferate. Keratocyte spreading and motility were also directed by the geometry of the underlying patterns. The results prove that microcP in conjunction with the use of PLL-g-PEG and its derivatives provides a simple and robust alternative to previously reported micropatterning methods for future cell biological and biotechnological applications.

  1. Studies on aqueous two phase polymer systems useful for partitioning of biological materials

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.; Bamberger, S.

    1982-01-01

    The two phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) (PEG) are mixed above a critical concentration of a few percent provide a useful medium for the separation of biological cell subpopulations via partition between the top, PEG-rich phase and the liquid-liquid phase boundary. Interfacial tensions of such systems have been measured by the rotating drop technique and found to range between 0.1-100 micro-N/m. The tension was found to depend on the length of the tie line describing the system on a phase diagram, via a power law relationship which differed depending on the concentration of Na phosphate buffer present. The electrokinetic properties of drops of one phase suspended in the other were studied for a variety of systems. It was found that the droplet electrophoretic mobility increased monotonically with phosphate concentration and drop diameter but exhibited the opposite sign from that anticipated from phosphate partition measurements. It was possible to take advantage of these electrokinetic properties and dramatically enhance the speed of phase separation through application of relatively small electric fields.

  2. Hydrophilic polymer drug from a derivative of salicylic acid: synthesis, controlled release studies and biological behavior.

    PubMed

    Rodríguez, Gema; Gallardo, Alberto; Fernández, Mar; Rebuelta, Mercedes; Buján, Julia; Bellón, Juan María; Honduvilla, Natalio G; Escudero, Cristina; San Román, Julio

    2004-06-25

    Hydrophilic polymeric drugs bearing "Triflusal" (4-trifluoromethylsalicylic acid), a drug widely used as antithrombogenic agent (Disgren), have been prepared by free radical copolymerization of methacryloyloxyethyl [2-(acetyloxy)-4-(trifluoromethyl)] benzoate (HTRF) and N,N'-dimethylacrylamide (DMA). The reactivity ratios of both monomers have been determined by 1H NMR spectra by applying non-linear least square treatments to the copolymerization equation (terminal model), and the kinetic parameters obtained indicated that the microstructure of copolymer chains is homogeneous, with a random distribution of the active HTRF units along the copolymer chains. That means that for the copolymer system THDMA22 used in this work, HTRF units are mainly isolated in relatively long DMA sequences. Therefore, in this structure the intramolecular interactions between adjacent HTRF units are negligible. Release of Triflusal from THDMA22 has been studied in vitro using buffered solutions at pH = 2, 7.4 and 10 and 37 degrees C. The system showed an interesting pseudo-zero order release profile at pH = 7.4 during several months. It has been also evaluated the pharmacological activity and the behavior of the system in contact with biological media. In this sense, we have carried out some in vitro studies about the antiaggregant properties and biocompatibility of THDMA22. Results demonstrate that this copolymer inhibits platelet aggregation in its macromolecular form and presents a good biocompatibility with Human Osteoblastic Cells (HOS).

  3. Studies on aqueous two phase polymer systems useful for partitioning of biological materials

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.; Bamberger, S.

    1982-01-01

    The two phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) (PEG) are mixed above a critical concentration of a few percent provide a useful medium for the separation of biological cell subpopulations via partition between the top, PEG-rich phase and the liquid-liquid phase boundary. Interfacial tensions of such systems have been measured by the rotating drop technique and found to range between 0.1-100 micro-N/m. The tension was found to depend on the length of the tie line describing the system on a phase diagram, via a power law relationship which differed depending on the concentration of Na phosphate buffer present. The electrokinetic properties of drops of one phase suspended in the other were studied for a variety of systems. It was found that the droplet electrophoretic mobility increased monotonically with phosphate concentration and drop diameter but exhibited the opposite sign from that anticipated from phosphate partition measurements. It was possible to take advantage of these electrokinetic properties and dramatically enhance the speed of phase separation through application of relatively small electric fields.

  4. Biologically Derived Soft Conducting Hydrogels Using Heparin-Doped Polymer Networks

    PubMed Central

    2015-01-01

    The emergence of flexible and stretchable electronic components expands the range of applications of electronic devices. Flexible devices are ideally suited for electronic biointerfaces because of mechanically permissive structures that conform to curvilinear structures found in native tissue. Most electronic materials used in these applications exhibit elastic moduli on the order of 0.1–1 MPa. However, many electronically excitable tissues exhibit elasticities in the range of 1–10 kPa, several orders of magnitude smaller than existing components used in flexible devices. This work describes the use of biologically derived heparins as scaffold materials for fabricating networks with hybrid electronic/ionic conductivity and ultracompliant mechanical properties. Photo-cross-linkable heparin–methacrylate hydrogels serve as templates to control the microstructure and doping of in situ polymerized polyaniline structures. Macroscopic heparin-doped polyaniline hydrogel dual networks exhibit impedances as low as Z = 4.17 Ω at 1 kHz and storage moduli of G′ = 900 ± 100 Pa. The conductivity of heparin/polyaniline networks depends on the oxidation state and microstructure of secondary polyaniline networks. Furthermore, heparin/polyaniline networks support the attachment, proliferation, and differentiation of murine myoblasts without any surface treatments. Taken together, these results suggest that heparin/polyaniline hydrogel networks exhibit suitable physical properties as an electronically active biointerface material that can match the mechanical properties of soft tissues composed of excitable cells. PMID:24738911

  5. The Constitutional Amendment Process

    ERIC Educational Resources Information Center

    Chism, Kahlil

    2005-01-01

    This article discusses the constitutional amendment process. Although the process is not described in great detail, Article V of the United States Constitution allows for and provides instruction on amending the Constitution. While the amendment process currently consists of six steps, the Constitution is nevertheless quite difficult to change.…

  6. The Constitutional Amendment Process

    ERIC Educational Resources Information Center

    Chism, Kahlil

    2005-01-01

    This article discusses the constitutional amendment process. Although the process is not described in great detail, Article V of the United States Constitution allows for and provides instruction on amending the Constitution. While the amendment process currently consists of six steps, the Constitution is nevertheless quite difficult to change.…

  7. In Situ Functionalized Polymers for siRNA Delivery.

    PubMed

    Priegue, Juan M; Crisan, Daniel N; Martínez-Costas, José; Granja, Juan R; Fernandez-Trillo, Francisco; Montenegro, Javier

    2016-06-20

    A new method is reported herein for screening the biological activity of functional polymers across a consistent degree of polymerization and in situ, that is, under aqueous conditions and without purification/isolation of candidate polymers. In brief, the chemical functionality of a poly(acryloyl hydrazide) scaffold was activated under aqueous conditions using readily available aldehydes to obtain amphiphilic polymers. The transport activity of the resulting polymers can be evaluated in situ using model membranes and living cells without the need for tedious isolation and purification steps. This technology allowed the rapid identification of a supramolecular polymeric vector with excellent efficiency and reproducibility for the delivery of siRNA into human cells (HeLa-EGFP). The reported method constitutes a blueprint for the high-throughput screening and future discovery of new polymeric functional materials with important biological applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Physicochemical characterisation and biological evaluation of hydrogel-poly(epsilon-caprolactone) interpenetrating polymer networks as novel urinary biomaterials.

    PubMed

    Jones, David S; McLaughlin, David W J; McCoy, Colin P; Gorman, Sean P

    2005-05-01

    Hydrogels are frequently employed as medical device biomaterials due to their advantageous biological properties, e.g. resistance to infection and encrustation, biocompatibility; however, their poor mechanical properties generally limit the scope of application to coatings of medical devices. To address this limitation, this study described the formulation of sequential interpenetrating polymer networks (IPN) of poly(-caprolactone) (PCL) and poly(hydroxyethylmethacrylate) (p(HEMA)). IPN containing 20% w/w PCL, p(HEMA), both in the presence or absence of ethyleneglycol dimethacrylate (EGDMA 1% w/w), were prepared by free radical polymerisation. Following preparation the degradation and the mechanical and surface properties of the biomaterials and, in addition, the resistances to microbial adherence and encrustation in vitro were examined. In comparison to p(HEMA) the various IPN exhibited substantially greater tensile properties (ultimate tensile strength, % elongation, Young's modulus) that were accredited to the discrete distribution of PCL within the hydrogel network. The IPN exhibited two glass transition temperatures that were statistically similar to those of the individual components, thereby providing evidence of the immiscible nature of the two polymers. The IPN possessed higher receding contact angles and lower equilibrium water contents in comparison to p(HEMA), whereas the limited degradation of the IPN at both pH 7 and 9 was deemed suitable for clinical usage for periods of at least 4 weeks. The resistances of the various IPN to bacterial adherence and urinary encrustation were examined using in vitro models. Importantly the resistance of the IPN to encrustation was, in general, similar to that of p(HEMA) but greater than that of PCL whereas, the resistance of the IPN to bacterial adherence was frequently greater than that of p(HEMA) and PCL. Therefore, this study has shown that the mechanical properties of p(HEMA) may be substantially increased by the

  9. Ligand stimulation of ErbB4 and a constitutively-active ErbB4 mutant result in different biological responses in human pancreatic tumor cell lines

    SciTech Connect

    Mill, Christopher P.; Gettinger, Kathleen L.; Riese, David J.

    2011-02-15

    Pancreatic cancer is the fourth leading cause of cancer death in the United States. Indeed, it has been estimated that 37,000 Americans will die from this disease in 2010. Late diagnosis, chemoresistance, and radioresistance of these tumors are major reasons for poor patient outcome, spurring the search for pancreatic cancer early diagnostic and therapeutic targets. ErbB4 (HER4) is a member of the ErbB family of receptor tyrosine kinases (RTKs), a family that also includes the Epidermal Growth Factor Receptor (EGFR/ErbB1/HER1), Neu/ErbB2/HER2, and ErbB3/HER3. These RTKs play central roles in many human malignancies by regulating cell proliferation, survival, differentiation, invasiveness, motility, and apoptosis. In this report we demonstrate that human pancreatic tumor cell lines exhibit minimal ErbB4 expression; in contrast, these cell lines exhibit varied and in some cases abundant expression and basal tyrosine phosphorylation of EGFR, ErbB2, and ErbB3. Expression of a constitutively-dimerized and -active ErbB4 mutant inhibits clonogenic proliferation of CaPan-1, HPAC, MIA PaCa-2, and PANC-1 pancreatic tumor cell lines. In contrast, expression of wild-type ErbB4 in pancreatic tumor cell lines potentiates stimulation of anchorage-independent colony formation by the ErbB4 ligand Neuregulin 1{beta}. These results illustrate the multiple roles that ErbB4 may be playing in pancreatic tumorigenesis and tumor progression.

  10. Ligand Stimulation of ErbB4 and A Constitutively-Active ErbB4 Mutant Result in Different Biological Responses In Human Pancreatic Tumor Cell Lines

    PubMed Central

    Mill, Christopher P.; Gettinger, Kathleen L.; Riese, David J.

    2010-01-01

    Pancreatic cancer is the fourth leading cause of cancer death in the United States. Indeed, it has been estimated that 37,000 Americans will die from this disease in 2010. Late diagnosis, chemoresistance, and radioresistance of these tumors are major reasons for poor patient outcome, spurring the search for pancreatic cancer early diagnostic and therapeutic targets. ErbB4 (HER4) is a member of the ErbB family of receptor tyrosine kinases (RTKs), a family that also includes the Epidermal Growth Factor Receptor (EGFR/ErbB1/HER1), Neu/ErbB2/HER2, and ErbB3/HER3. These RTKs play central roles in many human malignancies by regulating cell proliferation, survival, differentiation, invasiveness, motility, and apoptosis. In this report we demonstrate that human pancreatic tumor cell lines exhibit minimal ErbB4 expression; in contrast, these cell lines exhibit varied and in some cases abundant expression and basal tyrosine phosphorylation of EGFR, ErbB2, and ErbB3. Expression of a constitutively-dimerized and -active ErbB4 mutant inhibits clonogenic proliferation of CaPan-1, HPAC, MIA PaCa-2, and PANC-1 pancreatic tumor cell lines. In contrast, expression of wild-type ErbB4 in pancreatic tumor cell lines potentiates stimulation of anchorage-independent colony formation by the ErbB4 ligand Neuregulin1β. These results illustrate the multiple roles that ErbB4 may be playing in pancreatic tumorigenesis and tumor progression. PMID:21110957

  11. Efficient one-pot synthesis of hydrophilic and fluorescent molecularly imprinted polymer nanoparticles for direct drug quantification in real biological samples.

    PubMed

    Niu, Hui; Yang, Yaqiong; Zhang, Huiqi

    2015-12-15

    Efficient one-pot synthesis of hydrophilic and fluorescent molecularly imprinted polymer (MIP) nanoparticles and their application as optical chemosensor for direct drug quantification in real, undiluted biological samples are described. The general principle was demonstrated by preparing tetracycline (Tc, a broad-spectrum antibiotic)-imprinted fluorescent polymer nanoparticles bearing hydrophilic polymer brushes via poly(2-hydroxyethyl methacrylate) (PHEMA) macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization in the presence of a fluorescent monomer. The introduction of hydrophilic PHEMA brushes and fluorescence labeling onto/into the MIP nanoparticles proved to not only significantly improve their surface hydrophilicity and lead to their obvious specific binding and high selectivity toward Tc in the undiluted bovine serum, but also impart them with strong fluorescent properties. In particular, significant fluorescence quenching was observed upon their binding with Tc in such complex biological milieu, which makes these Tc-MIP nanoparticles useful optical chemosensor with a detection limit of 0.26 μM. Furthermore, such advanced functional MIP nanoparticles-based chemosensor was also successfully utilized for the direct, sensitive, and accurate determination of Tc in another biological medium (i.e., the undiluted pig serum) with average recoveries ranging from 98% to 102%, even in the presence of several interfering drugs.

  12. Three distinct clades of cultured heterocystous cyanobacteria constitute the dominant N2-fixing members of biological soil crusts of the Colorado Plateau, USA

    USGS Publications Warehouse

    Yeager, C.M.; Kornosky, J.L.; Morgan, R.E.; Cain, E.C.; Garcia-Pichel, F.; Housman, D.C.; Belnap, J.; Kuske, C.R.

    2007-01-01

    The identity of the numerically dominant N2-fixing bacteria in biological soil crusts of the Colorado Plateau region and two outlying areas was determined using multiple approaches, to link the environmental diversity of nifH gene sequences to cultured bacterial isolates from the regions. Of the nifH sequence-types detected in soil crusts of the Colorado Plateau, 89% (421/473) were most closely related to nifH signature sequences from cyanobacteria of the order Nostocales. N2-fixing cyanobacterial strains were cultured from crusts and their morphotypes, 16S rRNA gene and nifH gene sequences were characterized. The numerically dominant diazotrophs in the Colorado Plateau crusts fell within three clades of heterocystous cyanobacteria. Two clades are well-represented by phylogenetically and morphologically coherent strains, corresponding to the descriptions of Nostoc commune and Scytonema hyalinum, which are widely recognized as important N2-fixing components of soil crusts. A third, previously-overlooked clade was represented by a phylogenetically coherent but morphologically diverse group of strains that encompass the morphogenera Tolypothrix and Spirirestis. Many of the strains in each of these groups contained at least two nifH copies that represent different clusters in the nifH environmental survey. ?? 2007 Federation of European Microbiological Societies.

  13. Surface grafting of zwitterionic polymers onto dye doped AIE-active luminescent silica nanoparticles through surface-initiated ATRP for biological imaging applications

    NASA Astrophysics Data System (ADS)

    Mao, Liucheng; Liu, Xinhua; Liu, Meiying; Huang, Long; Xu, Dazhuang; Jiang, Ruming; Huang, Qiang; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-10-01

    Aggregation-induced emission (AIE) dyes have recently been intensively explored for biological imaging applications owing to their outstanding optical feature as compared with conventional organic dyes. The AIE-active luminescent silica nanoparticles (LSNPs) are expected to combine the advantages both of silica nanoparticles and AIE-active dyes. Although the AIE-active LSNPs have been prepared previously, surface modification of these AIE-active LSNPs with functional polymers has not been reported thus far. In this work, we reported a rather facile and general strategy for preparation of polymers functionalized AIE-active LSNPs through the surface-initiated atom transfer radical polymerization (ATRP). The AIE-active LSNPs were fabricated via direct encapsulation of AIE-active dye into silica nanoparticles through a non-covalent modified Stöber method. The ATRP initiator was subsequently immobilized onto these AIE-active LSNPs through amidation reaction between 3-aminopropyl-triethoxy-silane and 2-bromoisobutyryl bromide. Finally, the zwitterionic 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) was selected as model monomer and grafted onto MSNs through ATRP. The characterization results suggested that LSNPs can be successfully modified with poly(MPC) through surface-initiated ATRP. The biological evaluation results demonstrated that the final SNPs-AIE-pMPC composites possess low cytotoxicity, desirable optical properties and great potential for biological imaging. Taken together, we demonstrated that AIE-active LSNPs can be fabricated and surface modified with functional polymers to endow novel functions and better performance for biomedical applications. More importantly, this strategy developed in this work could also be extended for fabrication of many other LSNPs polymer composites owing to the good monomer adoptability of ATRP.

  14. Building a Genetic Manipulation Tool Box for Orchid Biology: Identification of Constitutive Promoters and Application of CRISPR/Cas9 in the Orchid, Dendrobium officinale

    PubMed Central

    Kui, Ling; Chen, Haitao; Zhang, Weixiong; He, Simei; Xiong, Zijun; Zhang, Yesheng; Yan, Liang; Zhong, Chaofang; He, Fengmei; Chen, Junwen; Zeng, Peng; Zhang, Guanghui; Yang, Shengchao; Dong, Yang; Wang, Wen; Cai, Jing

    2017-01-01

    . officinale. These efficient research tools will not only help create novel D. officinale varieties, but will also facilitate the molecular genetic investigation of orchid biology. PMID:28127299

  15. Building a Genetic Manipulation Tool Box for Orchid Biology: Identification of Constitutive Promoters and Application of CRISPR/Cas9 in the Orchid, Dendrobium officinale.

    PubMed

    Kui, Ling; Chen, Haitao; Zhang, Weixiong; He, Simei; Xiong, Zijun; Zhang, Yesheng; Yan, Liang; Zhong, Chaofang; He, Fengmei; Chen, Junwen; Zeng, Peng; Zhang, Guanghui; Yang, Shengchao; Dong, Yang; Wang, Wen; Cai, Jing

    2016-01-01

    . officinale. These efficient research tools will not only help create novel D. officinale varieties, but will also facilitate the molecular genetic investigation of orchid biology.

  16. Identification of functionally relevant populations in enhanced biological phosphorus removal processes based on intracellular polymers profiles and insights into the metabolic diversity and heterogeneity.

    PubMed

    Majed, Nehreen; Chernenko, Tatyana; Diem, Max; Gu, April Z

    2012-05-01

    This study proposed and demonstrated the application of a new Raman microscopy-based method for metabolic state-based identification and quantification of functionally relevant populations, namely polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), in enhanced biological phosphorus removal (EBPR) system via simultaneous detection of multiple intracellular polymers including polyphosphate (polyP), glycogen, and polyhydroxybutyrate (PHB). The unique Raman spectrum of different combinations of intracellular polymers within a cell at a given stage of the EBPR cycle allowed for its identification as PAO, GAO, or neither. The abundance of total PAOs and GAOs determined by Raman method were consistent with those obtained with polyP staining and fluorescence in situ hybridization (FISH). Different combinations and quantities of intracellular polymer inclusions observed in single cells revealed the distribution of different sub-PAOs groups among the total PAO populations, which exhibit phenotypic and metabolic heterogeneity and diversity. These results also provided evidence for the hypothesis that different PAOs may employ different extents of combination of glycolysis and TCA cycle pathways for anaerobic reducing power and energy generation and it is possible that some PAOs may rely on TCA cycle solely without glycolysis. Sum of cellular level quantification of the internal polymers associated with different population groups showed differentiated and distributed trends of glycogen and PHB level between PAOs and GAOs, which could not be elucidated before with conventional bulk measurements of EBPR mixed cultures. © 2012 American Chemical Society

  17. β-Cyclodextrin/thermosensitive containing polymer brushes grafted onto magnetite nano-particles for extraction and determination of venlafaxine in biological and pharmaceutical samples.

    PubMed

    Ahmad Panahi, Homayon; Alaei, Haniyeh Sadat

    2014-12-10

    In this paper, a novel nano-sorbent is fabricated by the surface grafting of poly[β-CD/allylamine-co-N-isopropylacrylamide] onto modified magnetite nano-particles by 3-mercaptopropyltrimethoxysilane. The polymer grafted magnetite nano-particles was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, scanning electron microscopy, and transmission electron microscopy. The feasibility of employing this nano-sorbent for extraction of trace venlafaxine in pharmaceutical samples and human biological fluids are investigated. The effect of various parameters such as pH, reaction temperature, and contact time was evaluated. The result revealed that the best sorption of venlafaxine by the magnetite nano-sorbent occurred at 35 °C at an optimum pH of 5. The kinetics of the venlafaxine shows accessibility of active sites in the grafted polymer onto the drug. The equilibrium data of venlafaxine by grafted magnetite nano-sorbent are well represented by the Langmuir and Freundlich isotherm models. The adsorption capacity of venlafaxine is found 142.8 mg g(-1) and indicated the homogeneous sites onto polymer grafted magnetite nano-sorbent surface. Nearly 80% of venlafaxine was released in simulated intestinal fluid, pH 7.4, in 30 h and 90% in simulated gastric fluid, pH 1.2, in 1 h. The venlafaxine loaded-polymer grafted magnetite nano-particles were successfully applied for the extraction in urine and pharmaceutical samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Melons are Branched Polymers

    NASA Astrophysics Data System (ADS)

    Gurau, Razvan; Ryan, James P.

    2014-11-01

    Melonic graphs constitute the family of graphs arising at leading order in the 1/N expansion of tensor models. They were shown to lead to a continuum phase, reminiscent of branched polymers. We show here that they are in fact precisely branched polymers, that is, they possess Hausdorff dimension 2 and spectral dimension 4/3.

  19. Contesting the Constitution: The Constitutional Dialogues.

    ERIC Educational Resources Information Center

    Hilenski, Ferdinand Alexi

    This historical dramatization, prepared for presentation at the 1985 Wyoming Chatauqua, contains three dialogues, set during the administration of President Thomas Jefferson and presenting the issues surrounding the drafting and ratification of the U.S. Constitution. The dialogues are designed to be presented in three segments to permit discussion…

  20. Contesting the Constitution: The Constitutional Dialogues.

    ERIC Educational Resources Information Center

    Hilenski, Ferdinand Alexi

    This historical dramatization, prepared for presentation at the 1985 Wyoming Chatauqua, contains three dialogues, set during the administration of President Thomas Jefferson and presenting the issues surrounding the drafting and ratification of the U.S. Constitution. The dialogues are designed to be presented in three segments to permit discussion…

  1. From commodity polymers to functional polymers.

    PubMed

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

    2014-04-08

    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.

  2. From Commodity Polymers to Functional Polymers

    PubMed Central

    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

  3. Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes

    NASA Astrophysics Data System (ADS)

    Khan, Shamim Ahmad; Nishat, Nahid; Parveen, Shadma; Rasool, Raza

    2011-10-01

    A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, 1H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand.

  4. Aqueous synthesis of multidentate-polymer-capping Ag2Se quantum dots with bright photoluminescence tunable in a second near-infrared biological window.

    PubMed

    Tan, Lianjiang; Wan, Ajun; Zhao, Tingting; Huang, Ran; Li, Huili

    2014-05-14

    A new strategy for fabricating water-dispersible Ag2Se quantum dots (QDs) is presented. A multidentate polymer (MDP) was synthesized and used as a capping agent for Ag2Se QDs. The MDP-capping Ag2Se QDs were synthesized in aqueous solution at room temperature, which are highly photoluminescent in a second near-infrared (NIR-II) biological window and possess good photostability. These readily prepared NIR-II fluorescent nanoprobes have great potential for biomedical applications, especially useful for in vivo imaging.

  5. Interpreting the Constitution.

    ERIC Educational Resources Information Center

    Brennan, William J., Jr.

    1987-01-01

    Discusses constitutional interpretations relating to capital punishment and protection of human dignity. Points out the document's effectiveness in creating a new society by adapting its principles to current problems and needs. Considers two views of the Constitution that lead to controversy over the legitimacy of judicial decisions. (PS)

  6. Constitutional Issues and Iowa.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1987-01-01

    Important constitutional issues are presented in a manner appropriate for use in the classroom. Case studies and events from the history of Iowa are used to illuminate the Constitution and Bill of Rights. Freedom of expression and students' rights are discussed in "The Black Armband Case"; free exercise of religion as won by the Iowa's…

  7. The Constitution by Cell

    ERIC Educational Resources Information Center

    Greenhut, Stephanie; Jones, Megan

    2010-01-01

    On their visit to the National Archives Experience in Washington, D.C., students in Jenni Ashley and Gay Brock's U.S. history classes at the Potomac School in McLean, Virginia, participated in a pilot program called "The Constitution by Cell." Armed with their cell phones, a basic understanding of the Constitution, and a willingness to…

  8. Teaching About the Constitution.

    ERIC Educational Resources Information Center

    White, Charles S.

    1988-01-01

    Reviews "The U.S. Constitution Then and Now," a two-unit program using the integrated database and word processing capabilities of AppleWorks. For grades 7-12, the units simulate the constitutional convention and the principles of free speech and privacy. Concludes that with adequate time, the program can provide a potentially powerful…

  9. Interpreting the Constitution.

    ERIC Educational Resources Information Center

    Brennan, William J., Jr.

    1987-01-01

    Discusses constitutional interpretations relating to capital punishment and protection of human dignity. Points out the document's effectiveness in creating a new society by adapting its principles to current problems and needs. Considers two views of the Constitution that lead to controversy over the legitimacy of judicial decisions. (PS)

  10. The Constitution by Cell

    ERIC Educational Resources Information Center

    Greenhut, Stephanie; Jones, Megan

    2010-01-01

    On their visit to the National Archives Experience in Washington, D.C., students in Jenni Ashley and Gay Brock's U.S. history classes at the Potomac School in McLean, Virginia, participated in a pilot program called "The Constitution by Cell." Armed with their cell phones, a basic understanding of the Constitution, and a willingness to…

  11. Polymer brushes containing thermosensitive and functional groups grafted onto magnetic nano-particles for interaction and extraction of famotidine in biological samples.

    PubMed

    Ahmad Panahi, Homayon; Nasrollahi, Sara

    2014-12-10

    This study introduces a new method for grafting poly[N-isopropylacrylamide-co-allyl glycidyl/iminodiacetic] onto iron oxide nano-particles modified using 3-mercaptopropyltrimethoxysilane. The grafted nano-polymer was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, transmission electron microscopy and scanning electron microscopy. The parameters of pH, contact time and temperature of the grafted nano-polymer were investigated. The determination and extraction of famotidine in human biological fluids was evaluated for high accessibility to active sites on the grafted sorbent. The equilibrium adsorption data were analyzed using the Langmuir and Freundlich models. The sorption capacity of the nano-sorbent was 116 mg g(-1) at an optimum pH of 7. About 73% of famotidine was released into simulated gastric fluid by 1 h and 70% was released into simulated intestinal fluids by 30 h at 37 °C. These results show that this new magnetic grafted nano-polymer is suitable for enteric drug delivery.

  12. Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers

    PubMed Central

    2015-01-01

    Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL–1. Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes PMID:26258729

  13. Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers.

    PubMed

    Congdon, Thomas; Dean, Bethany T; Kasperczak-Wright, James; Biggs, Caroline I; Notman, Rebecca; Gibson, Matthew I

    2015-09-14

    Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL(-1). Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes.

  14. Copolymers of ethylene imine and N-(2-hydroxyethyl)-ethylene imine as tools to study effects of polymer structure on physicochemical and biological properties of DNA complexes.

    PubMed

    Fischer, Dagmar; von Harpe, Anke; Kunath, Klaus; Petersen, Holger; Li, Youxin; Kissel, Thomas

    2002-01-01

    A series of five poly[(ethylene imine)-co-N-(2-hydroxyethyl-ethylene imine)] copolymers with similar molecular weights and different degrees of branching was established to study structure-function relationship with regard to physicochemical and biological properties as gene delivery systems. Copolymers were synthesized by acid-catalyzed ring-opening copolymerization of aziridine and N-(2-hydroxyethyl)-aziridine in aqueous solution and characterized by GPC-MALLS, (1)H- and (13)C NMR, IR, potentiometric titration, and ion exchange chromatography. Complexation of DNA was determined by agarose gel electrophoresis, and complex sizes were quantitated by PCS. Cytotoxicity of the copolymers in fibroblasts was assessed by MTT-assay, LDH-assay, and hemolysis. The transfection efficiency was determined using the reporter plasmid pGL3 in 3T3 mouse fibroblasts. The copolymers obtained by solution polymerization had relatively low molecular weights of about 2000 Da, and the degree of branching increased with increasing ethylene imine ratio. The pK(a) as well as the buffer capacity increased proportional to the number of primary and secondary amines. Higher branched polymers showed stronger complexation and condensation of DNA, formed smaller polymer/DNA complexes, and induced the expression of plasmids to a higher extent than less branched polymers. In vitro cytotoxic effects and the hemolysis of erythrocytes decreased with decreased branching. Our results indicate that the basicity and degree of protonation of the polymers depending on their amount of primary and secondary amines seem to be important factors both for their transfection efficiency and for their cytotoxicity in gene transfer.

  15. Polymer monolithic capillary microextraction on-line coupled with inductively coupled plasma-mass spectrometry for the determination of trace Au and Pd in biological samples

    NASA Astrophysics Data System (ADS)

    Liu, Xiaolan; He, Man; Chen, Beibei; Hu, Bin

    2014-11-01

    A novel method based on on-line polymer monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Au and Pd in biological samples. For this purpose, poly(glycidyl methacrylate-ethylene dimethacrylate) monolith was prepared and functionalized with mercapto groups. The prepared monolith exhibited good selectivity to Au and Pd, and good resistance to strong acid with a long life span. Factors affecting the extraction efficiency of CME, such as sample acidity, sample flow rate, eluent conditions and coexisting ion interference were investigated in detail. Under the optimal conditions, the limits of detection (LODs, 3σ) were 5.9 ng L- 1 for Au and 8.3 ng L- 1 for Pd, and the relative standard deviations (RSDs, c = 50 ng L -1, n = 7) were 6.5% for Au and 1.1% for Pd, respectively. The developed method was successfully applied to the determination of Au and Pd in human urine and serum samples with the recovery in the range of 84-118% for spiked samples. The developed on-line polymer monolithic CME-ICP-MS method has the advantages of rapidity, simplicity, low sample/reagent consumption, high sensitivity and is suitable for the determination of trace Au and Pd in biological samples with limited amount available and complex matrix.

  16. A Non-Biological Method for Screening Active Components against Influenza Virus from Traditional Chinese Medicine by Coupling a LC Column with Oseltamivir Molecularly Imprinted Polymers

    PubMed Central

    Yang, Ya-Jun; Li, Jian-Yong; Liu, Xi-Wang; Zhang, Ji-Yu; Liu, Yu-Rong; Li, Bing

    2013-01-01

    To develop a non-biological method for screening active components against influenza virus from traditional Chinese medicine (TCM) extraction, a liquid chromatography (LC) column prepared with oseltamivir molecularly imprinted polymer (OSMIP) was employed with LC-mass spectrometry (LC-MS). From chloroform extracts of compound TCM liquid preparation, we observed an affinitive component m/z 249, which was identified to be matrine following analysis of phytochemical literatures, OSMIP-LC column on-line of control compounds and MS/MS off-line. The results showed that matrine had similar bioactivities with OS against avian influenza virus H9N2 in vitro for both alleviating cytopathic effect and hemagglutination inhibition and that the stereostructures of these two compounds are similar while their two-dimensional structures were different. In addition, our results suggested that the bioactivities of those affinitive compounds were correlated with their chromatographic behaviors, in which less difference of the chromatographic behaviors might have more similar bioactivities. This indicates that matrine is a potential candidate drug to prevent or cure influenza for human or animal. In conclusion, the present study showed that molecularly imprinted polymers can be used as a non-biological method for screening active components against influenza virus from TCM. PMID:24386385

  17. - and Post-Workshop Assessment of Teachers and Students Attending the Scientific Workshop ``FROM Educational to Scientific Perspectives: Sugar Polymers in Biology and Their Applications''

    NASA Astrophysics Data System (ADS)

    Ufondu, Chuck; Ali, Nawab; Stapleton, Carl; Taylor, Loria; Barker, Linda; Tarasenko, Olga

    2011-06-01

    During summer 2010, a two-week-long scientific workshop "From educational to scientific perspectives: sugar polymers in biology and their applications" was offered for high school teachers and students at the University of Arkansas at Little Rock's Department of Biology. Teacher and student participants took part in science, technology, engineering, and mathematics (STEM) activities in order to improve math and science skills. Participants were taught various laboratory techniques, computer skills, Public Medical library searches, individual research project, PowerPoint presentation preparation, and a final oral presentation. Each participant was given pre- and post-workshop questionnaires, to gage initial and acquired knowledge. From the questionnaires, it was determined that there was a significant gain in knowledge of basic scientific concepts related to sugar polymers and their applications. It was found that 100% of participants—five teachers and seven students—reported their overall STEM experience as favorable. Furthermore, participants reported that the research project, computer techniques, and PowerPoint presentations were useful. This research experience provides knowledge about basic scientific concepts and is an excellent method to bridge the gap between high school and post-secondary education for both teachers and students.

  18. Preparation and biological evaluation of synthetic and polymer-encapsulated congeners of the antitumor agent pactamycin: Insight into functional group effects and biological activity

    PubMed Central

    Sharpe, Robert J.; Malinowski, Justin T.; Sorana, Federico; Luft, J. Christopher; Bowerman, Charles J.; DeSimone, Joseph M.; Johnson, Jeffrey S.

    2015-01-01

    The synthesis and biological analysis of a number of novel congeners of the aminocyclopentitol pactamycin is described. Specific attention was paid to the preparation of derivatives at crucial synthetic branch points of the parent structure, and biological assays revealed a number of insights into the source of pactamycin’s biological activity. Additionally, the encapsulation of pactamycin and select derivatives into the PRINT© nanoparticle technology was investigated as a proof-of-concept, and evidence of bioactivity modulation through nanoparticle delivery is demonstrated. This work has provided heretofore unrealized access to a large number of novel compounds for further evaluation. PMID:25792144

  19. Constitution, 29 October 1987.

    PubMed

    1987-01-01

    This document contains provisions of chapter 2 (Rights and Duties of Citizens) of the 1987 Constitution of the Republic of Korea relating to equality of the sexes, freedom of movement, free and compulsory education, equal opportunity at work, social protection, housing, and health care. The Constitution states that all citizens are equal before the law with no discrimination in political, economic, social, or cultural life based on sex, religion, or social status. The Constitution also protects freedom of residence and mobility, the right to an equal education, free compulsory education, and working mothers (with specific protection against discrimination). The Constitution directs the state to promote the welfare and rights of women, enhance the welfare of the aged and the young, and protect those incapable of earning a living. Housing development policies will be used to ensure comfortable housing for all citizens. State protection is afforded to mothers and to the health of all citizens.

  20. A Tailor-Made Synthetic Polymer for Cell Encapsulation: Design Rationale, Synthesis, Chemical-Physics and Biological Characterizations.

    PubMed

    Gerges, Irini; Tamplenizza, Margherita; Rossi, Eleonora; Tocchio, Alessandro; Martello, Federico; Recordati, Camilla; Kumar, Deepak; Forsyth, Nicholas R; Liu, Yang; Lenardi, Cristina

    2016-06-01

    This study presents a custom-made in situ gelling polymeric precursor for cell encapsulation. Composed of poly((2-hydroxyethyl)methacrylate-co-(3-aminopropyl)methacrylamide) (P(HEMA-co-APM) mother backbone and RGD-mimicking poly(amidoamine) (PAA) moiteis, the comb-like structured polymeric precursor is tailored to gather the advantages of the two families of synthetic polymers, i.e., the good mechanical integrity of PHEMA-based polymers and the biocompatibility and biodegradability of PAAs. The role of P(HEMA-co-APM) in the regulation of the chemico-physical properties of P(HEMA-co-APM)/PAA hydrogels is thoroughly investigated. On the basis of obtained results, namely the capability of maintaining vital NIH3T3 cell line in vitro for 2 d in a 3D cell culture, the in vivo biocompatibility in murine model for 16 d, and the ability of finely tuning mechanical properties and degradation kinetics, it can be assessed that P(HEMA-co-APM)/PAAs offer a cost-effective valid alternative to the so far studied natural polymer-based systems for cell encapsulation.

  1. The nanocrystalline coordination polymer of AMT-Ag for an effective detection of ciprofloxacin hydrochloride in pharmaceutical formulation and biological fluid.

    PubMed

    Tiwari, Madhu; Kumar, Ashish; Shankar, Uma; Prakash, Rajiv

    2016-11-15

    The present report highlights a cost effective and portable AMT-Ag nanocrystalline coordination polymer (NCCP) based electrochemical sensor for an efficient sensing of biologically active drug molecule ciprofloxacin hydrochloride (CFX). The AMT-Ag NCCP, is synthesized using an easily accessible organic ligand 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) with silver nitrate. In the infinite polymer array of AMT-Ag, silver (I) centers are bridged by tecton AMT through the exocyclic thiol and amino linkage. A successful ultra‒trace detection of CFX has been achieved due to the prominent electron channeling through the pores of polymeric nano-crystallites. The efficient charge transfer arises at the interface of electrolyte and AMT-Ag nano-crystals anchored electrode through hydrophobic interaction and π-π electron coupling. The voltammogram reveals the critical redox features of CFX and provides a clear representation about the steps involved in the AMT-Ag assisted oxidation of CFX. This specific signature further applied in the voltammetric assay of CFX in pharmaceutical formulation (eye drops) and biological fluid (urine) by a significantly high sensitivity (0.002µA/µM and 0.007µA/µM) and detection limit (22nM and 60nM) respectively without any interference. Therefore, the developed AMT-Ag NCCP could serve as a highly valuable platform for the fabrication of high-performance electrochemical sensors for the detection of biologically important drug molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Preparation and evaluation of a novel molecularly imprinted polymer coating for selective extraction of indomethacin from biological samples by electrochemically controlled in-tube solid phase microextraction.

    PubMed

    Asiabi, Hamid; Yamini, Yadollah; Seidi, Shahram; Ghahramanifard, Fazel

    2016-03-24

    In the present work, an automated on-line electrochemically controlled in-tube solid-phase microextraction (EC-in-tube SPME) coupled with HPLC-UV was developed for the selective extraction and preconcentration of indomethacin as a model analyte in biological samples. Applying an electrical potential can improve the extraction efficiency and provide more convenient manipulation of different properties of the extraction system including selectivity, clean-up, rate, and efficiency. For more enhancement of the selectivity and applicability of this method, a novel molecularly imprinted polymer coated tube was prepared and applied for extraction of indomethacin. For this purpose, nanostructured copolymer coating consisting of polypyrrole doped with ethylene glycol dimethacrylate was prepared on the inner surface of a stainless-steel tube by electrochemical synthesis. The characteristics and application of the tubes were investigated. Electron microscopy provided a cross linked porous surface and the average thickness of the MIP coating was 45 μm. Compared with the non-imprinted polymer coated tubes, the special selectivity for indomethacin was discovered with the molecularly imprinted coated tube. Moreover, stable and reproducible responses were obtained without being considerably influenced by interferences commonly existing in biological samples. Under the optimal conditions, the limits of detection were in the range of 0.07-2.0 μg L(-1) in different matrices. This method showed good linearity for indomethacin in the range of 0.1-200 μg L(-1), with coefficients of determination better than 0.996. The inter- and intra-assay precisions (RSD%, n = 3) were respectively in the range of 3.5-8.4% and 2.3-7.6% at three concentration levels of 7, 70 and 150 μg L(-1). The results showed that the proposed method can be successfully applied for selective analysis of indomethacin in biological samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    PubMed

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-04

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.

  4. Supramolecular Interactions in Chemomechanical Polymers

    PubMed Central

    SCHNEIDER, HANS-JÖRG; STRONGIN, ROBERT M.

    2009-01-01

    Conspectus Molecular recognition is the basis for the operation of most biological functions; outside of nature, it has also been developed to a high degree of sophistication within the framework of supramolecular chemistry. More recently, selective noncovalent interactions—which constitute molecular recognition—are being used in intelligent new materials that transform chemical signals into actions, such as the release of drugs. The presence of supramolecular binding sites allows chemomechanical polymers to operate as sensors and actuators within a single unit without the need for any additional devices such as transducers or power supplies. A polymer can be designed so that a particular chemical substance, most often in aqueous surroundings, will trigger either a large expansion or a large contraction, depending on the mechanism. The translation of binding energy into mechanical motion can, with a suitable arrangement of the materials in tubes or on flexible films, be harnessed for unidirectional drives, flow control, the liberation of drugs, or the uptake of toxic compounds, among other applications. Miniaturization of the polymer particles allows one to enhance both the sensitivity and speed of the response, which is of particular importance in sensing. The basis for the selective response to external effector compounds, such as metal ions, amino acids, peptides, or nucleotides, is their noncovalent interaction with complementary functions covalently bound to the polymer network. With suitable polymers, selectivity between structural isomers—and even between enantiomers—as triggers can be achieved. As with supramolecular complexes in solution, the underlying interactions in polymers comprise a variety of noncovalent binding mechanisms, which are not easy to distinguish and quantify—and more so with polymers, which are not monodisperse. In this Account, we present systematic comparisons of different polymers and effector classes that allow, for the

  5. Constitution, 15 August 1982.

    PubMed

    1987-01-01

    This document reprints major provisions of the 1982 Constitution of Equatorial Guinea. The Constitution calls for protection of the family as the basic building block of society. Foreigners are afforded the same civil rights as citizens and may seek asylum but may not exercise political rights. The Constitution guarantees equality before the law and prohibits discrimination based on ethnic background, race, sex, language, religion, filiation, political or other views, social origin, economic position, or birth. Women are afforded the same rights as men regardless of their marital status. The Constitution also guarantees citizens freedom to travel nationally and internationally and to choose a place of residence. Equatoguineans are also entitled to a standard of living that insures health, nutrition, education, clothing, housing, medical care, and necessary social services. The family policy contained in the Constitution protects all types of legal marriages equally and recognizes nonattachable and inalienable family patrimony. Children are protected from the time of conception, and all inhabitants are guaranteed a basic state education which is compulsory and free. Efforts are also being made to eradicate illiteracy. Women are insured training and promotion for their integration into the active life and development of the country, and farmers are guaranteed traditional ownership of the lands they possess, although the state retains the right of eminent domain.

  6. Preconcentration and Determination of Mefenamic Acid in Pharmaceutical and Biological Fluid Samples by Polymer-grafted Silica Gel Solid-phase Extraction Following High Performance Liquid Chromatography

    PubMed Central

    Bagheri Sadeghi, Hayedeh; Panahi, Homayon Ahmad; Mahabadi, Mahsa; Moniri, Elham

    2015-01-01

    Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, anti-infammatory and antipyretic actions. It is used to relieve mild to moderate pains. Solid-phase extraction of mefenamic acid by a polymer grafted to silica gel is reported. Poly allyl glycidyl ether/iminodiacetic acid-co-N, N-dimethylacrylamide was synthesized and grafted to silica gel and was used as an adsorbent for extraction of trace mefenamic acid in pharmaceutical and biological samples. Different factors affecting the extraction method were investigated and optimum conditions were obtained. The optimum pH value for sorption of mefenamic acid was 4.0. The sorption capacity of grafted adsorbent was 7.0 mg/g. The best eluent solvent was found to be trifluoroacetic acid-acetic acid in methanol with a recovery of 99.6%. The equilibrium adsorption data of mefenamic acid by grafted silica gel was analyzed by Langmuir model. The conformation of obtained data to Langmuir isotherm model reveals the homogeneous binding sites of grafted silica gel surface. Kinetic study of the mefenamic acid sorption by grafted silica gel indicates the good accessibility of the active sites in the grafted polymer. The sorption rate of the investigated mefenamic acid on the grafted silica gel was less than 5 min. This novel synthesized adsorbent can be successfully applied for the extraction of trace mefenamic acid in human plasma, urine and pharmaceutical samples. PMID:26330865

  7. One-pot synthesis of quantum dot-labeled hydrophilic molecularly imprinted polymer nanoparticles for direct optosensing of folic acid in real, undiluted biological samples.

    PubMed

    Yang, Yaqiong; Wang, Zhengzheng; Niu, Hui; Zhang, Huiqi

    2016-12-15

    A facile and efficient one-pot approach for the synthesis of quantum dot (QD)-labeled hydrophilic molecularly imprinted polymer (MIP) nanoparticles for direct optosensing of folic acid (FA) in the undiluted bovine and porcine serums is described. Hydrophilic macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization was used to implement the molecular imprinting of FA in the presence of CdTe quantum dots (QDs). The resulting FA-imprinted polymer nanoparticles with surface-grafted hydrophilic poly(glyceryl monomethacrylate) brushes and QDs labeling not only showed outstanding specific molecular recognition toward FA in biological samples, but also exhibited good photostability, rapid binding kinetics, and obvious template binding-induced fluorescence quenching. These characteristics make them a useful fluorescent chemosensor for directly and selectively optosensing FA in the undiluted bovine and porcine serums, with its limit of detection being 0.025μM and average recoveries ranging from 98% to 102%, even in the presence of several interfering compounds. This advanced fluorescent MIP chemosensor is highly promising for rapid quantification of FA in such applications as clinical diagnostics and food analysis.

  8. Fabrication of a Selective and Sensitive Sensor Based on Molecularly Imprinted Polymer/Acetylene Black for the Determination of Azithromycin in Pharmaceuticals and Biological Samples

    PubMed Central

    Zhou, Tingting; Tao, Yun; Jin, Hua; Song, Bin; Jing, Tao; Luo, Dan; Zhou, Yusun; Zhou, Yikai; Lee, Yong-Ill; Mei, Surong

    2016-01-01

    A new selective and sensitive sensor based on molecularly imprinted polymer/acetylene black (MIP/AB) was developed for the determination of azithromycin (AZM) in pharmaceuticals and biological samples. The MIP of AZM was synthesized by precipitation polymerization. MIP and AB were then respectively introduced as selective and sensitive elements for the preparation of MIP/AB-modified carbon paste (MIP/ABP) electrode. The performance of the obtained sensor was estimated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Compared with non-molecularly imprinted polymer (NIP) electrodes, NIP/ABP electrodes, and MIP-modified carbon paste electrodes, MIP/ABP electrode exhibited excellent current response toward AZM. The prepared sensor also exhibited good selectivity for AZM in comparison with structurally similar compounds. The effect of electrode composition, extraction parameters, and electrolyte conditions on the current response of the sensor was investigated. Under the optimized conditions, the prepared sensor showed two dynamic linear ranges of 1.0 × 10−7 mol L−1 to 2.0 × 10−6 mol L−1 and 2.0 × 10−6 mol L−1 to 2.0 × 10−5 mol L−1, with a limit of detection of 1.1 × 10−8 mol L−1. These predominant properties ensured that the sensor exhibits excellent reliability for detecting AZM in pharmaceuticals and biological fluids without the assistance of any separation techniques. The results were validated by the high-performance liquid chromatography–tandem mass spectrometry method. PMID:26820753

  9. Biological preconcentrator

    DOEpatents

    Manginell, Ronald P.; Bunker, Bruce C.; Huber, Dale L.

    2008-09-09

    A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

  10. Constitutional Law--Elective.

    ERIC Educational Resources Information Center

    Gallagher, Joan; Wood, Robert J.

    The elective unit on Constitutional Law is intended for 11th and 12th grade students. The unit is designed around major course goals which are to develop those concepts whereby students recognize and understand the following three topic areas: 1) Role of the Federal Judicial Branch of Government, 2) Supreme Court Cases Involving the Three Branches…

  11. The Constitutional Heritage.

    ERIC Educational Resources Information Center

    Baxter, Maurice

    Changing political, social, economic, and intellectual conditions over the past two hundred years have demanded innovation and adjustment of legal doctrine, thus giving the United States Constitution a character which the framers of the document could not have predicted. Historically, one must not only understand developments since 1787 but also…

  12. The Constitutional Heritage.

    ERIC Educational Resources Information Center

    Baxter, Maurice

    Changing political, social, economic, and intellectual conditions over the past two hundred years have demanded innovation and adjustment of legal doctrine, thus giving the United States Constitution a character which the framers of the document could not have predicted. Historically, one must not only understand developments since 1787 but also…

  13. Crushed Salt Constitutive Model

    SciTech Connect

    Callahan, G.D.

    1999-02-01

    The constitutive model used to describe the deformation of crushed salt is presented in this report. Two mechanisms -- dislocation creep and grain boundary diffusional pressure solution -- are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Upon complete consolidation, the crushed-salt model reproduces the Multimechanism Deformation (M-D) model typically used for the Waste Isolation Pilot Plant (WIPP) host geological formation salt. New shear consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on WIPP and southeastern New Mexico salt. Nonlinear least-squares model fitting to the database produced two sets of material parameter values for the model -- one for the shear consolidation tests and one for a combination of the shear and hydrostatic consolidation tests. Using the parameter values determined from the fitted database, the constitutive model is validated against constant strain-rate tests. Shaft seal problems are analyzed to demonstrate model-predicted consolidation of the shaft seal crushed-salt component. Based on the fitting statistics, the ability of the model to predict the test data, and the ability of the model to predict load paths and test data outside of the fitted database, the model appears to capture the creep consolidation behavior of crushed salt reasonably well.

  14. Constituting children's bodily integrity.

    PubMed

    Hill, B Jessie

    2015-04-01

    Children have a constitutional right to bodily integrity. Courts do not hesitate to vindicate that right when children are abused by state actors. Moreover, in at least some cases, a child's right to bodily integrity applies within the family, giving the child the right to avoid unwanted physical intrusions regardless of the parents' wishes. Nonetheless, the scope of this right vis-à-vis the parents is unclear; the extent to which it applies beyond the narrow context of abortion and contraception has been almost entirely unexplored and untheorized. This Article is the first in the legal literature to analyze the constitutional right of minors to bodily integrity within the family by spanning traditionally disparate doctrinal categories such as abortion rights; corporal punishment; medical decisionmaking; and nontherapeutic physical interventions such as tattooing, piercing, and circumcision. However, the constitutional right of minors to bodily integrity raises complex philosophical questions concerning the proper relationship between family and state, as well as difficult doctrinal and theoretical issues concerning the ever-murky idea of state action. This Article canvasses those issues with the ultimate goal of delineating a constitutional right of bodily security and autonomy for children.

  15. Sexuality and the Constitution.

    ERIC Educational Resources Information Center

    Copelon, Rhonda

    1987-01-01

    Argues for abortion rights and protection of intimate decisions and relationships. Describes the role and position of women in eighteenth century American society as a means of exposing the fallacy of the anti-abortion movement's insistence on adherence to constitutional text. Discusses the recent attempts to overturn the Roe v. Wade ruling. (PS)

  16. Gender and the Constitution

    ERIC Educational Resources Information Center

    Ginsburg, Ruth Bader

    1975-01-01

    In discussing the constitutional aspects of the sex-role debate in the U.S. the author traces the tradition, compares the present criterion of equal protection to the equal rights argument, and analyzes the equality principle with reference to affirmative action and to childbearing and childrearing, supporting the proposed equal rights amendment.…

  17. The Constitution in Action

    ERIC Educational Resources Information Center

    Potter, Lee Ann

    2007-01-01

    In this article, the author describes the experiences middle school students on a field trip to the new Constitution in Action Learning Lab in the Boeing Learning Center at the National Archives can expect. There, middle school students take on the roles of archivists and researchers collecting and analyzing primary sources from the holdings of…

  18. Sexuality and the Constitution.

    ERIC Educational Resources Information Center

    Copelon, Rhonda

    1987-01-01

    Argues for abortion rights and protection of intimate decisions and relationships. Describes the role and position of women in eighteenth century American society as a means of exposing the fallacy of the anti-abortion movement's insistence on adherence to constitutional text. Discusses the recent attempts to overturn the Roe v. Wade ruling. (PS)

  19. South Africa's Constitutional Change.

    ERIC Educational Resources Information Center

    Getman, Thomas

    1987-01-01

    Describes the striking dichotomy of South Africa's beauty and the squalor resulting from the apartheid policies of the government. Reviews reactions of black South Africans to recent constitutional changes and details efforts to secure more sweeping reform. Includes stories of several individuals who have taken actions which oppose the system of…

  20. A new magnetic ion-imprinted polymer as a highly selective sorbent for determination of cobalt in biological and environmental samples.

    PubMed

    Khoddami, Nafiseh; Shemirani, Farzaneh

    2016-01-01

    A magnetic ion-imprinted polymer (Fe3O4@TiO2@SiO2-IIP) functionalized with -NH groups for the selective determination of Co(II) ions from environmental and biological samples is presented. This sorbent was synthesized by surface imprinting technique combined with sol-gel process using 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) as a functional ligand, tetraethyl orthosilicate as across-linking agent, and Co(II) ion as the template. The prepared magnetic ion-imprinted polymer was characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). Fe3O4@TiO2@SiO2-IIP showed higher capacity and selectivity than that of Fe3O4@TiO2@SiO2-NIP. The important parameters influencing the recovery such as pH, the volume and eluent concentration, contact time, and the amount of sorbent on extraction percentage of Fe3O4@TiO2@SiO2-IIP were studied and optimized. The linear range (LR), relative standard deviation(RSD) and limit of detection (LOD=3 S(b)/m) for flame atomic absorption spectrometric determination of Co(II) ion, after its selective extraction by the prepared IIP polymer, were evaluated as 1-130 µg L(-1), 1.22% and 0.15 µg L(-1), respectively. The maximum capacity of Fe3O4@TiO2@SiO2-IIP and Fe3O4@TiO2@SiO2-NIP is 35.21 mg g(-1) and 10.34 mg g(-1), respectively. The separation factor of Fe3O4@TiO2@SiO2-IIP for Co(II)/Pb(II), Co(II)/Ni(II), and Co(II)/Cd(II) are 41.17, 79.74, and 56.48, respectively. In addition, the spent magnetic ion-imprinted polymer can be refreshed by simply washing with an aqueous HNO3 solution, and there is no significant decrease in adsorption capacity after a test of upto seven cycles, demonstrating that the Fe3O4@ TiO2@SiO2-IIP is stable and reusable.

  1. Protein-style dynamical transition in a non-biological polymer and a non-aqueous solvent

    SciTech Connect

    Mamontov, E.; Sharma, V. K.; Borreguero, J. M.; Tyagi, M.

    2016-03-15

    Using neutron scattering and molecular dynamics simulation, techniques most often associated with protein dynamical transition studies, we have investigated the microscopic dynamics of one of the most common polymers, polystyrene, which was exposed to toluene vapor, mimicking the process of protein hydration from water vapor. Polystyrene with adsorbed toluene is an example of a solvent-solute system, which, unlike biopolymers, is anhydrous and lacks hydrogen bonding. Nevertheless, it exhibits the essential traits of the dynamical transition in biomolecules, such as a specific dependence of the microscopic dynamics of both solvent and host on the temperature and the amount of solvent adsorbed. Ultimately, we conclude that the protein dynamical transition is a manifestation of a universal solvent-solute dynamical relationship, which is not specific to either biomolecules as solute, or aqueous media as solvent, or even a particular type of interactions between solvent and solute.

  2. Protein-style dynamical transition in a non-biological polymer and a non-aqueous solvent

    DOE PAGES

    Mamontov, E.; Sharma, V. K.; Borreguero, J. M.; ...

    2016-03-15

    Using neutron scattering and molecular dynamics simulation, techniques most often associated with protein dynamical transition studies, we have investigated the microscopic dynamics of one of the most common polymers, polystyrene, which was exposed to toluene vapor, mimicking the process of protein hydration from water vapor. Polystyrene with adsorbed toluene is an example of a solvent-solute system, which, unlike biopolymers, is anhydrous and lacks hydrogen bonding. Nevertheless, it exhibits the essential traits of the dynamical transition in biomolecules, such as a specific dependence of the microscopic dynamics of both solvent and host on the temperature and the amount of solvent adsorbed.more » Ultimately, we conclude that the protein dynamical transition is a manifestation of a universal solvent-solute dynamical relationship, which is not specific to either biomolecules as solute, or aqueous media as solvent, or even a particular type of interactions between solvent and solute.« less

  3. Elucidation of molecular structures at buried polymer interfaces and biological interfaces using sum frequency generation vibrational spectroscopy

    PubMed Central

    Zhang, Chi; Myers, John; Chen, Zhan

    2013-01-01

    Sum frequency generation (SFG) vibrational spectroscopy has been developed into an important technique to study surfaces and interfaces. It can probe buried interfaces in situ and provide molecular level structural information such as the presence of various chemical moieties, quantitative molecular functional group orientation, and time dependent kinetics or dynamics at such interfaces. This paper focuses on these three most important advantages of SFG and reviews some of the recent progress in SFG studies on interfaces related to polymer materials and biomolecules. The results discussed here demonstrate that SFG can provide important molecular structural information of buried interfaces in situ and in real time, which is difficult to obtain by other surface sensitive analytical techniques. PMID:23710244

  4. Fetal pain, abortion, viability, and the Constitution.

    PubMed

    Cohen, I Glenn; Sayeed, Sadath

    2011-01-01

    In early 2010, the Nebraska state legislature passed a new abortion restricting law asserting a new, compelling state interest in preventing fetal pain. In this article, we review existing constitutional abortion doctrine and note difficulties presented by persistent legal attention to a socially derived viability construct. We then offer a substantive biological, ethical, and legal critique of the new fetal pain rationale.

  5. Polymers from biobased materials

    SciTech Connect

    Chum, H.L.

    1991-01-01

    This book reports on polymers from biobased materials which are polymers derived from renewable resources by chemical or combined chemical and mechanical methods, or produced directly in biological processes. Combinations of renewable and conventional fossil-fuel-derived plastics are also biobased materials. This assessment reviews materials from renewable resources and their properties, including major biopolymers produced by plants and selected animal sources.

  6. Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare earth elements in biological samples.

    PubMed

    Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin

    2013-07-01

    A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare earth elements were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare earth elements in biological samples with limited sample volume.

  7. Dual-emissive Polymer Dots for Rapid Detection of Fluoride in Pure Water and Biological Systems with Improved Reliability and Accuracy

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Zhang, Chuanqi; Liu, Shujuan; Liu, Yahong; Zhang, Kenneth Yin; Zhou, Xiaobo; Jiang, Jiayang; Xu, Wenjuan; Yang, Tianshe; Huang, Wei

    2015-11-01

    It is of paramount importance to develop new probes that can selectively, sensitively, accurately and rapidly detect fluoride in aqueous media and biological systems, because F- is found to be closely related to many health and environmental concerns. Herein, a dual-emissive conjugated polyelectrolyte P1 containing phosphorescent iridium(III) complex was designed and synthesized, which can form ultrasmall polymer dots (Pdots) in aqueous media. The F--responsive tert-butyldiphenylsilyl moiety was introduced into iridium(III) complex as the signaling unit for sensing F- with the quenched phosphorescence. Thus, the dual-emissive Pdots can rapidly and accurately detect F- in aqueous media and live cells as a ratiometric probe by measuring the change in the ratio of the F--sensitive red phosphorescence from iridium(III) complex to the F--insensitive blue fluorescence from polyfluorene. Moreover, the interaction of Pdots with F- also changes its emission lifetime, and the lifetime-based detection of F- in live cells has been realized through photoluminescence lifetime imaging microscopy for the first time. Both the ratiometric luminescence and lifetime imaging have been demonstrated to be resistant to external influences, such as the probe’s concentration and excitation power. This study provides a new perspective for the design of promising Pdots-based probes for biological applications.

  8. Constitution, 29 March 1987.

    PubMed

    1987-01-01

    This document contains provisions of Haiti's 1987 Constitution relating to the family; the protection of children, aliens, and refugees; and individual rights. The age of majority in Haiti is 18, and political and civil rights are attained at age 21 regardless of sex or marital status. Haitians are equal before the law but native-born Haitians who have never renounced their nationality have special advantages. Human rights are guaranteed in conformity with the Universal Declaration of the Rights of Man. Every citizen has the right to decent housing, education, food, and social security. The state is obligated to provide citizens with appropriate means to protect, maintain, and restore their health. Primary schooling is compulsory and free. Aliens in Haiti enjoy the protection offered citizens, including a limited right to own real property. Political refugees have a right to asylum. The family is considered the foundation of society and enjoys state protection regardless of whether the family is constituted within the bonds of marriage. Legal protection is afforded mothers, children, and the aged. The Constitution also calls for creation of a Family Code to ensure protection and respect for the rights of the family.

  9. Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

    NASA Astrophysics Data System (ADS)

    Furuta, T.; Maeyama, T.; Ishikawa, K. L.; Fukunishi, N.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Hayashi, S.

    2015-08-01

    In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning.

  10. Protein-Style Dynamical Transition in a Non-Biological Polymer and a Non-Aqueous Solvent.

    PubMed

    Mamontov, E; Sharma, V K; Borreguero, J M; Tyagi, M

    2016-03-31

    Temperature-dependent onset of apparent anharmonicity in the microscopic dynamics of hydrated proteins and other biomolecules has been known as protein dynamical transition for the last quarter of a century. Using neutron scattering and molecular dynamics simulation, techniques most often associated with protein dynamical transition studies, we have investigated the microscopic dynamics of one of the most common polymers, polystyrene, which was exposed to toluene vapor, mimicking the process of protein hydration from water vapor. Polystyrene with adsorbed toluene is an example of a solvent-solute system, which, unlike biopolymers, is anhydrous and lacks hydrogen bonding. Nevertheless, it exhibits the essential traits of the dynamical transition in biomolecules, such as a specific dependence of the microscopic dynamics of both solvent and host on the temperature and the amount of solvent adsorbed. We conclude that the protein dynamical transition is a manifestation of a universal solvent-solute dynamical relationship, which is not specific to either biomolecules as solute, or aqueous media as solvent, or even a particular type of interactions between solvent and solute.

  11. The Constitution in Other Lands.

    ERIC Educational Resources Information Center

    Bill of Rights in Action, 1987

    1987-01-01

    Designed for classroom teaching, this document contains articles on the new constitutions of Japan, South Korea, and the Philippine Islands which were modeled in part on the U.S. Constitution. These countries' experiences with constitutional government are examined, and whether or not the U.S. Constitution can be a suitable model for other…

  12. Thomas Jefferson and the Constitution.

    ERIC Educational Resources Information Center

    Peterson, Merrill D.

    1987-01-01

    Examines Thomas Jefferson's role in the making and interpretation of the United States Constitution. Discusses the dominant features of Jefferson's constitutional theory; the character of Jefferson's presidency; and Jefferson's ongoing concern about constitutional preservation and change. Lists important dates in the history of the constitution.…

  13. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    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.

  14. Polymer films

    DOEpatents

    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.

  15. Physical properties of immiscible polymers

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    The demixing of immiscible polymers in low gravity is discussed. Applications of knowledge gained in this research will provide a better understanding of the role of phase segregation in determining the properties of polymer blends made from immiscible polymers. Knowledge will also be gained regarding the purification of biological materials by partitioning between the two liquid phases formed by solution of the polymers polyethylene glycol and dextran in water. Testing of new apparatus for space flight, extension of affinity phase partitioning, refinement of polymer chemistry, and demixing of isopycnic polymer phases in a one gravity environment are discussed.

  16. Constitutive equations of ageing polymeric materials

    NASA Technical Reports Server (NTRS)

    Peng, S. T. J.

    1985-01-01

    The constitutive equation for the relaxation behavior of time-dependent, chemically unstable materials developed by Valanis and Peng (1983), which used the irreversible thermodynamics of internal variables in Eyring's absolute reaction theory and yielded a theoretical expression for the effect of chemical crosslink density on the relaxation rate, is presently applied to the creep behavior of a network polymer which is undergoing a scission process. In particular, two equations are derived which may for the first time show the relations between mechanical models and internal variables in the creep expressions, using a three-element model with a Maxwell element.

  17. Constitutive equations of ageing polymeric materials

    NASA Technical Reports Server (NTRS)

    Peng, S. T. J.

    1985-01-01

    The constitutive equation for the relaxation behavior of time-dependent, chemically unstable materials developed by Valanis and Peng (1983), which used the irreversible thermodynamics of internal variables in Eyring's absolute reaction theory and yielded a theoretical expression for the effect of chemical crosslink density on the relaxation rate, is presently applied to the creep behavior of a network polymer which is undergoing a scission process. In particular, two equations are derived which may for the first time show the relations between mechanical models and internal variables in the creep expressions, using a three-element model with a Maxwell element.

  18. Constitution, 30 September 1987.

    PubMed

    1987-01-01

    This document reprints provisions of Suriname's 1987 Constitution relating to freedom of movement, equality of the sexes, the right to life, the right to physical integrity, equal opportunity in employment, the family, children, maternity benefits, the right to health care, parental responsibilities, free and compulsory education, illiteracy, and housing. All citizens enjoy freedom of movement within the bounds of the law. All people within the territory may claim protection of their person and property, and discrimination is forbidden on the basis of birth, sex, race, language, religion, education, political beliefs, economic position, or other status. Torture or inhuman treatment and punishment is banned, and the right to life is protected by the law. The state guarantees the right to work, and all employees have the right to equal remuneration for equal work, safe working conditions, and sufficient rest and recreation. The family is protected, and husbands and wives are equal before the law. Children have the right to protection, and working women are entitled to paid maternity leave. The state promotes the right to good health by systematic improvements in living and working conditions and dissemination of health education. The right to education is protected by the provision of free general primary education and efforts of the state to enable all citizens to achieve the highest educational levels possible. The Constitution also calls for the institution of a plan to allow the state to create public housing.

  19. Ethics and constitutional government.

    PubMed

    Albright, James A

    2007-01-01

    The term ethics refers to a set of principles that govern acceptable, proper conduct. Attacks on the Constitution of the United States pose the most serious breach of ethics today. Our country was founded as a republic, not as a democracy. Our Founding Fathers' main concern was to protect citizens from the power of the federal government, so constitutionally, the central government has little or no authority over individual citizens except on federal property. One of the major problems today is the fact that we now have professional politicians. This is due in large part to the lure of financial gain from countless special interest groups. This would change under constitutional law because the federal budget would decrease drastically. Article 1 states that all legislative power is vested in Congress. Congress has only 18 enumerated powers, and almost half of these pertain to defense of the country. Many of our current problems are due to regulatory agencies that have become independent fiefdoms with unconstitutional legislative, as well as executive and judicial, powers. The regulatory agency most relevant to medicine, both clinical care and research, is the FDA. It is now obvious that its basic structure needs to be changed or abolished because its actions are identical to those inherent in authoritarian systems. Constructive change could come from Congress, but it would be most desirable if the Supreme Court would take the lead and reestablish the authority of the Constitution as the Supreme Law of the Land. The FDA's function could be limited to the determination of safety, but preferably its mission would be altered to that of product certification. Defenders of the current system claim that such a drastic change would be too dangerous and their prime example is thalidomide. But it is now known that the market has already solved that problem prior to the government-imposed sanctions. Realistically, market forces and their ramifications, including our legal

  20. Methods for Calculating the Absolute Entropy and free energy of biological systems based on ideas from Polymer Physics

    PubMed Central

    Meirovitch, Hagai

    2009-01-01

    The commonly used simulation techniques, Metropolis Monte Carlo (MC) and molecular dynamics (MD) are of a dynamical type which enables one to sample system configurations i correctly with the Boltzmann probability, PiB while the value of PiB is not provided directly; therefore, it is difficult to obtain the absolute entropy, S ~ -ln PiB, and the Helmholtz free energy, F. With a different simulation approach developed in polymer physics, a chain is grown step-by-step with transition probabilities (TPs), and thus their product is the value of the construction probability; therefore, the entropy is known. Because all exact simulation methods are equivalent, i.e. they lead to the same averages and fluctuations of physical properties, one can treat an MC or MD sample as if its members have rather been generated step-by-step. Thus, each configuration i of the sample can be reconstructed (from nothing) by calculating the TPs with which it could have been constructed. This idea applies also to bulk systems such as fluids or magnets. This approach has led earlier to the “local states” (LS) and the “hypothetical scanning” (HS) methods, which are approximate in nature. A recent development is the hypothetical scanning Monte Carlo (HSMC) (or molecular dynamics, HSMD) method which is based on stochastic TPs where all interactions are taken into account. In this respect HSMC(D) can be viewed as exact and the only approximation involved is due to insufficient MC(MD) sampling for calculating the TPs. The validity of HSMC has been established by applying it first to liquid argon, TIP3P water, self-avoiding walks, and polyglycine models, where the results for F were found to agree with those obtained by other methods. Subsequently, HSMD was applied to mobile loops of the enzymes porcine pancreatic α-amylase and acetylcholineesterase in explicit water, where the difference of F between the bound and free states of the loop was calculated. Currently HSMD is being extended for

  1. Methods for calculating the absolute entropy and free energy of biological systems based on ideas from polymer physics.

    PubMed

    Meirovitch, Hagai

    2010-01-01

    The commonly used simulation techniques, Metropolis Monte Carlo (MC) and molecular dynamics (MD) are of a dynamical type which enables one to sample system configurations i correctly with the Boltzmann probability, P(i)(B), while the value of P(i)(B) is not provided directly; therefore, it is difficult to obtain the absolute entropy, S approximately -ln P(i)(B), and the Helmholtz free energy, F. With a different simulation approach developed in polymer physics, a chain is grown step-by-step with transition probabilities (TPs), and thus their product is the value of the construction probability; therefore, the entropy is known. Because all exact simulation methods are equivalent, i.e. they lead to the same averages and fluctuations of physical properties, one can treat an MC or MD sample as if its members have rather been generated step-by-step. Thus, each configuration i of the sample can be reconstructed (from nothing) by calculating the TPs with which it could have been constructed. This idea applies also to bulk systems such as fluids or magnets. This approach has led earlier to the "local states" (LS) and the "hypothetical scanning" (HS) methods, which are approximate in nature. A recent development is the hypothetical scanning Monte Carlo (HSMC) (or molecular dynamics, HSMD) method which is based on stochastic TPs where all interactions are taken into account. In this respect, HSMC(D) can be viewed as exact and the only approximation involved is due to insufficient MC(MD) sampling for calculating the TPs. The validity of HSMC has been established by applying it first to liquid argon, TIP3P water, self-avoiding walks (SAW), and polyglycine models, where the results for F were found to agree with those obtained by other methods. Subsequently, HSMD was applied to mobile loops of the enzymes porcine pancreatic alpha-amylase and acetylcholinesterase in explicit water, where the difference in F between the bound and free states of the loop was calculated. Currently

  2. The roles of loosely-bound and tightly-bound extracellular polymer substances in enhanced biological phosphorus removal.

    PubMed

    Long, Xiangyu; Tang, Ran; Fang, Zhendong; Xie, Chaoxin; Li, Yongqin; Xian, Guang

    2017-09-22

    Extracellular polymeric substances (EPS) have be founded to participate in the process of enhanced biological phosphorus removal (EBPR), but the exact role of EPS in EBPR process is unclear. In this work, the roles of loosely-bound EPS (LB-EPS), tightly-bound EPS (TB-EPS) and microbial cell in EBPR were explored, taking the activated sludge from 4 lab-scale A/O-SBR reactors with different temperatures and organic substrates as objects. It was founded that the P of EBPR activated sludge was mainly stored in TB-EPS, but the P of non-EBPR activated sludge was primarily located in microbial cell. The P release and uptake of EBPR activated sludge was attributed to the combined action of TB-EPS and microbial cell. Furthermore, TB-EPS played an more important role than microbial cell in EBPR process. With the analysis of (31)P NMR spectroscopy, both polyP and orthoP were the main phosphorus species of TB-EPS in EBPR sludge, but only orthoP was the main phosphorus species of LB-EPS and microbial cell. During the anaerobic-aerobic cycle, the roles of LB-EPS, TB-EPS and microbial cell in transfer and transformation of P in EBPR sludge were obviously different. LB-EPS transported and retained orthoP, and microbial cell directly anaerobically released or aerobically absorbed orthoP. Importantly, TB-EPS not only transported and retained orthoP, but also participated in biological phosphorus accumulation. The EBPR performance of sludge was closely related with the polyp in TB-EPS, which might be synthesized and decomposed by extracellular enzyme. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Artificially Engineered Protein Polymers.

    PubMed

    Yang, Yun Jung; Holmberg, Angela L; Olsen, Bradley D

    2017-06-07

    Modern polymer science increasingly requires precise control over macromolecular structure and properties for engineering advanced materials and biomedical systems. The application of biological processes to design and synthesize artificial protein polymers offers a means for furthering macromolecular tunability, enabling polymers with dispersities of ∼1.0 and monomer-level sequence control. Taking inspiration from materials evolved in nature, scientists have created modular building blocks with simplified monomer sequences that replicate the function of natural systems. The corresponding protein engineering toolbox has enabled the systematic development of complex functional polymeric materials across areas as diverse as adhesives, responsive polymers, and medical materials. This review discusses the natural proteins that have inspired the development of key building blocks for protein polymer engineering and the function of these elements in material design. The prospects and progress for scalable commercialization of protein polymers are reviewed, discussing both technology needs and opportunities.

  4. Fast and Simple Preparation of Patterned Surfaces with Hydrophilic Polymer Brushes by Micromolding in Capillaries.

    PubMed

    Vonhören, Benjamin; Langer, Marcel; Abt, Doris; Barner-Kowollik, Christopher; Ravoo, Bart Jan

    2015-12-22

    Micropatterns of hydrophilic polymer brushes were prepared by micromolding in capillaries (MIMIC). The polymers are covalently bound to the surfaces by a rapid hetero Diels-Alder reaction, constituting the first example of polymers grafted to surfaces in a defined pattern by MIMIC. The polymers [poly(acrylic acid), poly(hydroxyethyl acrylate), and poly(tetraethylene glycol acrylate) ranging in molecular weight from 1500 to 6000 g mol(-1)] were prepared with narrow dispersities via the reversible addition-fragmentation chain transfer (RAFT) process using a highly electron deficient RAFT agent that can react with surface-anchored dienes such as cyclopentadiene. We demonstrate that the anchoring method is facile to perform and highly suitable for preparing patterned surfaces that are passivated against biological impact in well-defined areas.

  5. Constitution, 5 May 1989.

    PubMed

    1989-01-01

    This document contains provisions of Cambodia's Constitution of May 5, 1989. Article 7 gives men and women equal rights in marriage and the family, calls for monogamous marriages, and affords social protection to mothers and children. Article 8 guides parent-child relationships. The 14th article defines state property, and the 15th gives citizens full rights to own, use, and inherit land. The use of agricultural and forested land can only be changed with permission. Article 22 assigns educational responsibilities to the state, including free elementary education and a gradual expansion of higher education. Adult literacy classes are also promoted. Article 26 guarantees free medical consultations, and article 27 gives women a 90-day paid maternity leave. Breast-feeding women are also given special privileges. Article 33 guarantees the right to pay equity and to social security benefits. Article 36 grants the freedom to travel, the inviolability of homes, and privacy in correspondence of all types.

  6. Constitution, 5 October 1988.

    PubMed

    1989-01-01

    This document contains major provisions of the constitution adopted by Brazil on 5 October 1988. This constitution seeks to promote the welfare of all citizens without discrimination. The equality of all citizens is guaranteed, and the equal rights of women are specifically mentioned. Property rights are also guaranteed and defined. Female inmates are granted the right to remain with their children while breast feeding. Workers are guaranteed a minimum wage, a family allowance for dependents, maternity/paternity leave, specific incentives to protect the labor market for women, retirement benefits, free day care for preschool-age children, pay equity, and equal rights between tenured and sporadically employed workers. Agrarian reform provisions are given, including the authority to expropriate land. Social and economic policies to promote health are called for, and public health services are to be decentralized, to be integrated, and to foster community participation. Pension plan and social assistance provisions are outlined as are duties of the state in regard to education. The amount of money to be dedicated to education is set out, and a national educational plan is called for to achieve such goals as the eradication of illiteracy, the universalization of school attendance, the improvement of instruction, and the provision of vocational training. Specific measures are set out to protect and preserve the environment. Family policy deals with issues of marriage, the definition of a family, divorce, the right to family planning services, and the deterrence of domestic violence. Social protection provisions cover mothers and children, handicapped persons, and protection of minors. Finally, the customs and rights of Indians are protected, with special provisions given to protect land tenure and to protect the rights of Indians in water resource development and prospecting and mining activities.

  7. Constitutive models in LAME.

    SciTech Connect

    Hammerand, Daniel Carl; Scherzinger, William Mark

    2007-09-01

    The Library of Advanced Materials for Engineering (LAME) provides a common repository for constitutive models that can be used in computational solid mechanics codes. A number of models including both hypoelastic (rate) and hyperelastic (total strain) constitutive forms have been implemented in LAME. The structure and testing of LAME is described in Scherzinger and Hammerand ([3] and [4]). The purpose of the present report is to describe the material models which have already been implemented into LAME. The descriptions are designed to give useful information to both analysts and code developers. Thus far, 33 non-ITAR/non-CRADA protected material models have been incorporated. These include everything from the simple isotropic linear elastic models to a number of elastic-plastic models for metals to models for honeycomb, foams, potting epoxies and rubber. A complete description of each model is outside the scope of the current report. Rather, the aim here is to delineate the properties, state variables, functions, and methods for each model. However, a brief description of some of the constitutive details is provided for a number of the material models. Where appropriate, the SAND reports available for each model have been cited. Many models have state variable aliases for some or all of their state variables. These alias names can be used for outputting desired quantities. The state variable aliases available for results output have been listed in this report. However, not all models use these aliases. For those models, no state variable names are listed. Nevertheless, the number of state variables employed by each model is always given. Currently, there are four possible functions for a material model. This report lists which of these four methods are employed in each material model. As far as analysts are concerned, this information is included only for the awareness purposes. The analyst can take confidence in the fact that model has been properly implemented

  8. Polymer Electrolytes for Lithium/Sulfur Batteries

    PubMed Central

    Zhao, Yan; Zhang, Yongguang; Gosselink, Denise; Doan, The Nam Long; Sadhu, Mikhail; Cheang, Ho-Jae; Chen, Pu

    2012-01-01

    This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S) batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes. PMID:24958296

  9. This Constitution: A Bicentennial Chronicle.

    ERIC Educational Resources Information Center

    This Constitution, 1986

    1986-01-01

    Providing a link between constitutional scholars and the planners of school and public programs observing the Bicentennial of the United States Constitution, this series of the Bicentennial Chronicles features articles that provide a link between scholars of the Constitution and the people who will be planning programs for the public and for the…

  10. How Democratic Is the Constitution?

    ERIC Educational Resources Information Center

    Goldwin, Robert A., Ed.; Schambra, William A., Ed.

    Designed to help prepare the nation for a thoughtful observance of the Constitutional bicentennial, this publication contains seven essays on the topic of democracy and the Constitution. "Democracy and the Constitution" (Gordon S. Wood) looks at the popular and democratic rhetoric used to justify the federalist system in the late 1700's.…

  11. Constitution, 3 February 1987.

    PubMed

    1987-01-01

    This document contains provisions of the 1987 Constitution of the Philippines. The state policies reprinted from Article 2 note that the state recognizes the sanctity of family life and protects the life of the mother and of the unborn from conception. Women and men are afforded equality before the law. The state prioritizes education, science and technology, arts, culture, and sports and promotes comprehensive rural development and agrarian reform. Provisions reprinted from Article 13 (Social Justice and Human Rights) cover agrarian and natural resources reform, urban land reform and housing, health, and protection of women in the workforce. Sections from Article 14 (Education, Science and Technology, Arts, Culture, and Sports) set forth the state's duty to make quality education accessible to all citizens through a compulsory system of free public education, provision of incentives to deserving students, encouragement of informal education, and provision of adult education. Article 15, on the family, recognizes the family as the foundation of the nation and marriage as the foundation of the family. Spouses have the right to found a family, children have the right to appropriate care, the family has the right to a living wage and income, families or family associations have the right to participate in the planning and implementation of policies and programs that affect them, and the family has the duty to care for its elderly.

  12. Constitution, 1989. [Selected provisions].

    PubMed

    1989-01-01

    Chapter XII of the Hungarian Constitution, 1989, details the Fundamental Rights and Duties of Citizens. Everyone lawfully within the territory of Hungary has the right to liberty of movement and the freedom to choose his or her residence, except when restricted by law, including the right to leave his or her residence or county. The Republic of Hungary grants asylum to foreign citizens who were persecuted for racial, religious ethnic, linguistic, or political reasons. Men and women shall equally enjoy all civil, political, economic, social and political rights. Mothers are entitled to special care and protection before and after childbirth; women and juveniles are protected at work by special regulations. Every child has the right to special care an assistance from his or her family, the State, and society, for appropriate physical, spiritual, and moral development. Parents shall decide the kind of education their children receive. Hungary grants equal rights to all person within its territories, without regard to race, color, sex, language, religion, political, or other opinion, national, and social origin, property, birth and other status. Prejudicial discrimination shall be severely punished. Everyone has the right to work, to the free choice of employment and profession and to equal pay for equal work. Citizens have the right to social security, including social services necessary in old age, sickness, disability, widowhood, orphanhood an unemployment through no fault of their own. Hungary guarantees the right to culture for its citizens and realized this right by free and compulsory elementary education, by secondary and higher education which is accessible to all on the basis of capacity, and by the financial support of those receiving an education.

  13. Ion-exchange polymer artificial muscle and actuating system

    NASA Astrophysics Data System (ADS)

    Vial, Dominique; Tondu, Bertrand; Lopez, Pierre; Aurelle, Yves; Ricard, Alain

    1996-04-01

    Chemomechanical transformations are used to produce a mechanical force from a reversible chemical reaction in order to generate artificial muscular contraction, on the model of the biological muscle. The design and experimentation of an original artificial muscle using an ion-exchange polymer which reacts inside a soft envelope, derived from research on pneumatic artificial McKibben muscle, is presented. Then a chemomechanical actuator constituted of two artificial muscles has been conceived: first results are shown on position control in open-loop mode.

  14. Supramolecular Polymers in Aqueous Media.

    PubMed

    Krieg, Elisha; Bastings, Maartje M C; Besenius, Pol; Rybtchinski, Boris

    2016-02-24

    This review discusses one-dimensional supramolecular polymers that form in aqueous media. First, naturally occurring supramolecular polymers are described, in particular, amyloid fibrils, actin filaments, and microtubules. Their structural, thermodynamic, kinetic, and nanomechanical properties are highlighted, as well as their importance for the advancement of biologically inspired supramolecular polymer materials. Second, five classes of synthetic supramolecular polymers are described: systems based on (1) hydrogen-bond motifs, (2) large π-conjugated surfaces, (3) host-guest interactions, (4) peptides, and (5) DNA. We focus on recent studies that address key challenges in the field, providing mechanistic understanding, rational polymer design, important functionality, robustness, or unusual thermodynamic and kinetic properties.

  15. Exact and efficient calculation of Lagrange multipliers in biological polymers with constrained bond lengths and bond angles: proteins and nucleic acids as example cases.

    PubMed

    García-Risueño, Pablo; Echenique, Pablo; Alonso, J L

    2011-11-15

    To accelerate molecular dynamics simulations, it is common to impose holonomic constraints on the hardest degrees of freedom. In this way, the time step used to integrate the equations of motion can be increased, thereby allowing longer total simulation times. The imposition of such constraints results in an aditional set of N(c) equations (the equations of constraint) and unknowns (their associated Lagrange multipliers), whose solution is closely related to any algorithm implementing the constraints in Euclidean coordinates. In this work, it is shown that, due to the essentially linear structure of typical biological polymers the algebraic equations that need to be solved involve a matrix which is not only sparse, but also banded if the constraints are indexed in a skilful way. This allows the Lagrange multipliers to be obtained through a noniterative procedure, which can be considered exact up to machine precision, and which takes O(N(c)) operations, instead of the usual O(N c3) for generic molecular systems. We develop the formalism, and describe the appropriate indexing for a number of model molecules. Finally, we provide a numerical example of the technique in a series of polyalanine peptides of different lengths. Although a use of the Lagrange multipliers without any modification in the solution of the underlying ordinary differential equations yields unstable integration algorithms, the central role of these quantities makes their efficient calculation useful for the improvement of methods that correctly enforce the exact satisfaction of the constraints at each time step. We provide several examples of this.

  16. Synthesis and study of a molecularly imprinted polymer for specific solid-phase extraction of vinflunine and its metabolite from biological fluids.

    PubMed

    Lopez, Claire; Claude, Bérengère; Morin, Philippe; Pelissou, Martine; Pena, Richard; Max, Jean-Paul; Ribet, Jean-Paul

    2011-08-01

    A molecularly imprinted polymer (MIP) was synthesized in order to specifically extract vinflunine, an anticancer agent, and its metabolite (4-O-deacetylvinflunine) from bovine plasma and artificial urine by solid-phase extraction (SPE). Vinorelbine, a non-fluorinated analogue of vinflunine, was selected as a template for MIP synthesis. The selectivity of MIP versus the template (vinorelbine) and other alkaloids (catharanthine, vinblastine, vincristine, vinflunine and 4-O-deacetylvinflunine) was shown by a SPE protocol carried out with non-aqueous samples. A second protocol was developed for aqueous samples with two consecutive washing steps (AcOH-NH2 OH buffer (pH 7, I=10 mM)-MeOH mixture 95:5 v/v and ACN-AcOH mixture 99:1 v/v) and an elution step (MeOH-AcOH mixture 90:10 v/v). Thus, MIP-SPE of bovine plasma brought high recoveries, 81 and 89% for vinflunine and its metabolite, respectively. This protocol was slightly modified for artificial urine samples in order to obtain a good MIP/NIP selectivity; furthermore, elution recoveries were 73 and 81% for vinflunine and its metabolite, respectively. Repeatability was assessed in both biological matrices and RSD (%) were inferior to 4%. The MIP also showed a suitable linearity (r(2) superior to 0.99), between 0.25 and 10 μg/mL for plasma, and between 1 and 5 μg/mL for artificial urine.

  17. Sequence-controlled polymers.

    PubMed

    Lutz, Jean-François; Ouchi, Makoto; Liu, David R; Sawamoto, Mitsuo

    2013-08-09

    Sequence-controlled polymers are macromolecules in which monomer units of different chemical nature are arranged in an ordered fashion. The most prominent examples are biological and have been studied and used primarily by molecular biologists and biochemists. However, recent progress in protein- and DNA-based nanotechnologies has shown the relevance of sequence-controlled polymers to nonbiological applications, including data storage, nanoelectronics, and catalysis. In addition, synthetic polymer chemistry has provided interesting routes for preparing nonnatural sequence-controlled polymers. Although these synthetic macromolecules do not yet compare in functional scope with their natural counterparts, they open up opportunities for controlling the structure, self-assembly, and macroscopic properties of polymer materials.

  18. Essential Medicines in National Constitutions

    PubMed Central

    Toebes, Brigit; Hogerzeil, Hans

    2016-01-01

    Abstract A constitutional guarantee of access to essential medicines has been identified as an important indicator of government commitment to the progressive realization of the right to the highest attainable standard of health. The objective of this study was to evaluate provisions on access to essential medicines in national constitutions, to identify comprehensive examples of constitutional text on medicines that can be used as a model for other countries, and to evaluate the evolution of constitutional medicines-related rights since 2008. Relevant articles were selected from an inventory of constitutional texts from WHO member states. References to states’ legal obligations under international human rights law were evaluated. Twenty-two constitutions worldwide now oblige governments to protect and/or to fulfill accessibility of, availability of, and/or quality of medicines. Since 2008, state responsibilities to fulfill access to essential medicines have expanded in five constitutions, been maintained in four constitutions, and have regressed in one constitution. Government commitments to essential medicines are an important foundation of health system equity and are included increasingly in state constitutions. PMID:27781006

  19. Elasticity of semiflexible polymers.

    PubMed

    Samuel, Joseph; Sinha, Supurna

    2002-11-01

    We present a method for solving the wormlike chain model for semiflexible polymers to any desired accuracy over the entire range of polymer lengths. Our results are in excellent agreement with recent computer simulations and reproduce important qualitatively interesting features observed in simulations of polymers of intermediate lengths. We also make a number of predictions that can be tested in a variety of concrete experimental realizations. The expected level of finite size fluctuations in force-extension curves is also estimated. This study is relevant to mechanical properties of biological molecules.

  20. Inorganic and Organometallic Polymers

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, Vadapalli

    This textbook is intended to give an understanding of the basic principles that constitute the field of non-conventional polymers containing inorganic and organometalic units as the repeating units. Each chapter will be self-explanatory with a good background so that it can be easily understood at the senior undergraduate level. The principles involved in the preparation of these polymers, their characterisation and their applications will be discussed. Basic inorganic chemistry required for the understanding of each topic is presented so that the content of the chapter is readily understood.

  1. Constitutional Issues--Watergate and the Constitution. Teaching with Documents.

    ERIC Educational Resources Information Center

    National Archives and Records Administration, Washington, DC.

    When U.S. President Richard Nixon resigned in 1974 in the wake of the Watergate scandal, it was only the second time that impeachment of a president had been considered. Although the U.S. Constitution has provisions for a person removed from office to be indicted, there are no guidelines in the Constitution about a President who has resigned. The…

  2. Microgravity Polymers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    A one-day, interactive workshop considering the effects of gravity on polymer materials science was held in Cleveland, Ohio, on May 9, 1985. Selected programmatic and technical issues were reviewed to introduce the field to workshop participants. Parallel discussions were conducted in three disciplinary working groups: polymer chemistry, polymer physics, and polymer engineering. This proceedings presents summaries of the workshop discussions and conclusions.

  3. Bi-isotropic constitutive relations

    NASA Astrophysics Data System (ADS)

    Sihvola, A. H.; Lindell, I. V.

    1991-03-01

    The constitutive relations of general bi-isotropic media, requiring four material parameters, can be written in different ways to describe their electromagnetic behavior. This communication contains a two-way 'dictionary' between a proposed formulation of the constitutive relations with three other sets of relations, generalized from relations used for chiral materials.

  4. The Constitution and Citizenship Education.

    ERIC Educational Resources Information Center

    Shoemaker, Rebecca S.

    The paper takes the position that the study and understanding of the United States Constitution should be a critical part of citizenship education, especially as its Bicentennial approaches. Several factors suggest that the Constitution has become the most durable document of its kind in history, and that its teaching should be centered in both…

  5. The Constitution and American Radicalism.

    ERIC Educational Resources Information Center

    Lobel, Jules

    1987-01-01

    Discusses the history of the following movements' attitudes towards the Constitution: (1) abolition; (2) feminism; (3) trade unions; (4) socialism and communism; and (5) civil rights and anti-war. Maintains that the tensions in these movements' towards the Constitution represent basic contradictions in the document itself. (PS)

  6. Constitutional Law and Liberal Education.

    ERIC Educational Resources Information Center

    Clor, Harry

    1985-01-01

    By studying constitutional law, students learn about the relationship between democratic theory and practice, one of the main concerns of liberal education. The mind is enlarged when it must apply ethical standards and political ideas to real human problems. How a political science professor teaches constitutional law is discussed. (RM)

  7. Reordering American Constitutional Law Teaching.

    ERIC Educational Resources Information Center

    Gerber, Scott D.

    1994-01-01

    Maintains that constitutional law is the cornerstone of an undergraduate public law curriculum. Asserts that there is a welcome trend toward teaching the subject over a two-semester sequence, instead of only one. Describes course content and teaching strategies used in a college constitutional law course. (CFR)

  8. How Capitalistic Is the Constitution?

    ERIC Educational Resources Information Center

    Goldwin, Robert A., Ed.; Schambra, William A., Ed.

    Second in a three-part series designed to help prepare the nation for a thoughtful observance of the Constitutional bicentennial, this publication contains seven essays on the topic of capitalism and the Constitution. "American Democracy and the Acquisitive Spirit" (Marc F. Plattner) supports the argument that the framers of the…

  9. Constitution And Bylaws: 2004 Edition

    ERIC Educational Resources Information Center

    Distance Education and Training Council, 2004

    2004-01-01

    This document contains the constitution and bylaws of the Distance Education and Training Council. The constitution and bylaws include 13 articles. Sections include: Name; Mission and Goals; Administration of the Council; Membership; Meetings; The Commission; Terms of Office; Officers; Committees; Compensation; Dues and Assessments; Miscellaneous…

  10. The Constitution and Its Critics

    ERIC Educational Resources Information Center

    Main, Thomas J.

    2011-01-01

    In planning a freshman undergraduate curriculum with colleagues recently, the question arose as to what type of understanding educators wanted to impart to their students about the Constitution. The alleged defects of the Constitution that these books point to are wide-ranging and can be classified into various categories. Some problems--such as…

  11. [Biogeography: geography or biology?].

    PubMed

    Kafanov, A I

    2009-01-01

    General biogeography is an interdisciplinary science, which combines geographic and biological aspects constituting two distinct research fields: biological geography and geographic biology. These fields differ in the nature of their objects of study, employ different methods and represent Earth sciences and biological sciences, respectively. It is suggested therefore that the classification codes for research fields and the state professional education standard should be revised.

  12. Polymers for Drug Delivery Systems

    PubMed Central

    Liechty, William B.; Kryscio, David R.; Slaughter, Brandon V.; Peppas, Nicholas A.

    2012-01-01

    Polymers have played an integral role in the advancement of drug delivery technology by providing controlled release of therapeutic agents in constant doses over long periods, cyclic dosage, and tunable release of both hydrophilic and hydrophobic drugs. From early beginnings using off-the-shelf materials, the field has grown tremendously, driven in part by the innovations of chemical engineers. Modern advances in drug delivery are now predicated upon the rational design of polymers tailored for specific cargo and engineered to exert distinct biological functions. In this review, we highlight the fundamental drug delivery systems and their mathematical foundations and discuss the physiological barriers to drug delivery. We review the origins and applications of stimuli-responsive polymer systems and polymer therapeutics such as polymer-protein and polymer-drug conjugates. The latest developments in polymers capable of molecular recognition or directing intracellular delivery are surveyed to illustrate areas of research advancing the frontiers of drug delivery. PMID:22432577

  13. Constitutional aneuploidy and cancer predisposition†

    PubMed Central

    Ganmore, Ithamar; Smooha, Gil; Izraeli, Shai

    2009-01-01

    Constitutional aneuploidies are rare syndromes associated with multiple developmental abnormalities and the alterations in the risk for specific cancers. Acquired somatic chromosomal aneuploidies are the most common genetic aberrations in sporadic cancers. Thus studies of these rare constitutional aneuploidy syndromes are important not only for patient counseling and clinical management, but also for deciphering the mechanisms by which chromosomal aneuploidy affect cancer initiation and progression. Here we review the major constitutional aneuploidy syndromes and suggest some general mechanisms for the associated cancer predisposition. PMID:19297405

  14. Remarks on turbulent constitutive relations

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing; Lumley, John L.

    1993-01-01

    The paper demonstrates that the concept of turbulent constitutive relations can be used to construct general models for various turbulent correlations. Some of the Generalized Cayley-Hamilton formulas for relating tensor products of higher extension to tensor products of lower extension are introduced. The combination of dimensional analysis and invariant theory can lead to 'turbulent constitutive relations' (or general turbulence models) for, in principle, any turbulent correlations. As examples, the constitutive relations for Reynolds stresses and scalar fluxes are derived. The results are consistent with ones from Renormalization Group (RNG) theory and two-scale Direct-Interaction Approximation (DIA) method, but with a more general form.

  15. Polymer chemistry - an overview

    SciTech Connect

    Droske, J.P.

    1993-12-31

    As a result of their high molecular weights, which range from several thousand to well over a million, polymers (or macromolecules) exhibit unique properties. Examples of these unusual properties and explanations for them will be highlighted in this presentation. Polymers comprise a very important class of materials which can be categorized into two groups; biopolymers and synthetic polymers. Biopolymers are essential components in biological systems and some of these, such as wool and silk, have found application as important industrial materials. Building on nature`s insights, chemists have prepared a wide variety of synthetic polymers. These materials play a major role in established as well as state-of-the-art technologies. An overview of the fundamental principles of this broad field will be presented.

  16. The President and the Constitution.

    ERIC Educational Resources Information Center

    Toler, Frank

    1988-01-01

    Intended for ninth grade students, this ten day unit focuses on the constitutional powers of the President of the United States. Included are worksheets, vocabulary, writing assignments, tests, and quizzes. (JDH)

  17. Are Sanctions on Employers Constitutional?

    ERIC Educational Resources Information Center

    Gollobin, Ira

    1988-01-01

    Questions the constitutional validity of employer sanctions used to deter illegal immigration under the Immigration Reform and Control Act. Points out the anomaly of using criminal penalties to deter a civil, administrative violation. (FMW)

  18. Abnormal human sex chromosome constitutions

    SciTech Connect

    1993-12-31

    Chapter 22, discusses abnormal human sex chromosome constitution. Aneuploidy of X chromosomes with a female phenotype, sex chromosome aneuploidy with a male phenotype, and various abnormalities in X chromosome behavior are described. 31 refs., 2 figs.

  19. Constitutive modeling for isotropic materials

    NASA Technical Reports Server (NTRS)

    Lindholm, U. S.

    1984-01-01

    A state-of-the-art review of applicable constitutive models with selection of two for detailed comparison with a wide range of experimental tests was conducted. The experimental matrix contained uniaxial and biaxial tensile, creep, stress relaxation, and cyclic fatigue tests at temperatures to 1093 C and strain rates from .0000001 to .001/sec. Some nonisothermal cycles will also be run. The constitutive models will be incorporated into the MARC finite element structural analysis program with a demonstration computation made for advanced turbine blade configuration. In the code development work, particular emphasis is being placed on developing efficient integration algorithms for the highly nonlinear and stiff constitutive equations. Another area of emphasis is the appropriate and efficient methodology for determing constitutive constants from a minimum extent of experimental data.

  20. Are Sanctions on Employers Constitutional?

    ERIC Educational Resources Information Center

    Gollobin, Ira

    1988-01-01

    Questions the constitutional validity of employer sanctions used to deter illegal immigration under the Immigration Reform and Control Act. Points out the anomaly of using criminal penalties to deter a civil, administrative violation. (FMW)

  1. The Constitution's Prescription for Freedom.

    ERIC Educational Resources Information Center

    Peach, Lucinda

    1986-01-01

    Examines how the framers of the Constitution came to choose our system of government, how that system was designed to function, and how the separation of powers has served to maintain our democracy despite attempts to violate it. (JDH)

  2. The Constitution's Prescription for Freedom.

    ERIC Educational Resources Information Center

    Peach, Lucinda

    1986-01-01

    Examines how the framers of the Constitution came to choose our system of government, how that system was designed to function, and how the separation of powers has served to maintain our democracy despite attempts to violate it. (JDH)

  3. Constitutive modeling for isotropic materials

    NASA Technical Reports Server (NTRS)

    Ramaswamy, V. G.; Vanstone, R. H.; Dame, L. T.; Laflen, J. H.

    1984-01-01

    The unified constitutive theories for application to typical isotropic cast nickel base supperalloys used for air-cooled turbine blades were evaluated. The specific modeling aspects evaluated were: uniaxial, monotonic, cyclic, creep, relaxation, multiaxial, notch, and thermomechanical behavior. Further development of the constitutive theories to model thermal history effects, refinement of the material test procedures, evaluation of coating effects, and verification of the models in an alternate material will be accomplished in a follow-on for this base program.

  4. Kenya Promulgates a New Constitution

    DTIC Science & Technology

    2011-03-10

    issues of governance , rights and individual freedoms. Subsequently a process to write a new constitution started in 2003. It was all inclusive and...all inclusive and participatory in decision-making. The process for reviewing the constitution was reactivated in earnest and delegates drawn from...changes in the separation of powers between the three arms of government , major matters of citizenship , the Bill of Rights, the devolution of government

  5. Molecular dynamics modeling the synthetic and biological polymers interactions pre-studied via docking: anchors modified polyanions interference with the HIV-1 fusion mediator.

    PubMed

    Tsvetkov, Vladimir B; Serbin, Alexander V

    2014-06-01

    In previous works we reported the design, synthesis and in vitro evaluations of synthetic anionic polymers modified by alicyclic pendant groups (hydrophobic anchors), as a novel class of inhibitors of the human immunodeficiency virus type 1 (HIV-1) entry into human cells. Recently, these synthetic polymers interactions with key mediator of HIV-1 entry-fusion, the tri-helix core of the first heptad repeat regions [HR1]3 of viral envelope protein gp41, were pre-studied via docking in terms of newly formulated algorithm for stepwise approximation from fragments of polymeric backbone and side-group models toward real polymeric chains. In the present article the docking results were verified under molecular dynamics (MD) modeling. In contrast with limited capabilities of the docking, the MD allowed of using much more large models of the polymeric ligands, considering flexibility of both ligand and target simultaneously. Among the synthesized polymers the dinorbornen anchors containing alternating copolymers of maleic acid were selected as the most representative ligands (possessing the top anti-HIV activity in vitro in correlation with the highest binding energy in the docking). To verify the probability of binding of the polymers with the [HR1]3 in the sites defined via docking, various starting positions of polymer chains were tried. The MD simulations confirmed the main docking-predicted priority for binding sites, and possibilities for axial and belting modes of the ligands-target interactions. Some newly MD-discovered aspects of the ligand's backbone and anchor units dynamic cooperation in binding the viral target clarify mechanisms of the synthetic polymers anti-HIV activity and drug resistance prevention.

  6. Constitutive characterization of vocal fold viscoelasticity based on a modified Arruda-Boyce eight-chain model

    NASA Astrophysics Data System (ADS)

    Chan, Roger W.

    2003-10-01

    Previous studies have shown that vocal fold tissues exhibit nonlinear viscoelastic behavior under different loading conditions. Hysteresis and strain rate dependence of stress-strain curves have been observed for vocal fold ligament and muscle tissues when subjected to sinusoidal tensile loading. Nonlinear viscoelastic response and tissue failure have also been described for vocal fold mucosa subjected to constant strain-rate tests under large-strain shear. These findings cannot be adequately described by the traditional constitutive formulations of linear and quasilinear viscoelasticity. This study attempts to characterize some nonlinear behavior of vocal fold tissues under tensile loading based on a modified version of the Arruda-Boyce (Bergström-Boyce) hyperelastic model for polymers, which has been shown to adequately predict the rate-dependent behavior of some elastomers and biological tissues. Results indicated that the model was only capable of describing the relatively linear portion of the nonlinear stress-strain curves of the vocal fold muscle (at strain smaller than 20%), while failing to predict the exponential increase of stress at higher strain. However, the model was capable of predicting the dependence of stress on strain rate reasonably well. This finding was consistent with the model's assumptions on the constitutive behavior of the two constituent polymer networks.

  7. Micromechanical model for isolated polymer-colloid clusters under tension

    NASA Astrophysics Data System (ADS)

    Dargazany, Roozbeh; Lin, Jiaqi; Khalili, Leila; Itskov, Mikhail; Chen, Hsieh; Alexander-Katz, Alfredo

    2016-10-01

    Binary polymer-colloid (PC) composites form the majority of biological load-bearing materials. Due to the abundance of the polymer and particles, and their simple aggregation process, PC clusters are used broadly by nature to create biomaterials with a variety of functions. However, our understanding of the mechanical features of the clusters and their load transfer mechanism is limited. Our main focus in this paper is the elastic behavior of close-packed PC clusters formed in the presence of polymer linkers. Therefore, a micromechanical model is proposed to predict the constitutive behavior of isolated polymer-colloid clusters under tension. The mechanical response of a cluster is considered to be governed by a backbone chain, which is the stress path that transfers most of the applied load. The developed model can reproduce the mean behavior of the clusters and is not dependent on their local geometry. The model utilizes four geometrical parameters for defining six shape descriptor functions which can affect the geometrical change of the clusters in the course of deformation. The predictions of the model are benchmarked against an extensive set of simulations by coarse-grained-Brownian dynamics, where clusters with different shapes and sizes were considered. The model exhibits good agreement with these simulations, which, besides its relative simplicity, makes the model an excellent add-on module for implementation into multiscale models of nanocomposites.

  8. Polymers at membranes

    NASA Astrophysics Data System (ADS)

    Breidenich, Markus

    2000-11-01

    The surface of biological cells consists of a lipid membrane and a large amount of various proteins and polymers, which are embedded in the membrane or attached to it. We investigate how membranes are influenced by polymers, which are anchored to the membrane by one end. The entropic pressure exerted by the polymer induces a curvature, which bends the membrane away from the polymer. The resulting membrane shape profile is a cone in the vicinity of the anchor segment and a catenoid far away from it. The perturbative calculations are confirmed by Monte-Carlo simulations. An additional attractive interaction between polymer and membrane reduces the entropically induced curvature. In the limit of strong adsorption, the polymer is localized directly on the membrane surface and does not induce any pressure, i.e. the membrane curvature vanishes. If the polymer is not anchored directly on the membrane surface, but in a non-vanishing anchoring distance, the membrane bends towards the polymer for strong adsorption. In the last part of the thesis, we study membranes under the influence of non-anchored polymers in solution. In the limit of pure steric interactions between the membrane and free polymers, the membrane curves towards the polymers (in contrast to the case of anchored polymers). In the limit of strong adsorption the membrane bends away from the polymers. Die Oberfläche biologischer Zellen besteht aus einer Lipidmembran und einer Vielzahl von Proteinen und Polymeren, die in die Membran eingebaut sind. Die Beeinflussung der Membran durch Polymere, die mit einem Ende an der Membran verankert sind, wird im Rahmen dieser Arbeit anhand eines vereinfachten biomimetischen Systems studiert. Der entropische Druck, den das Polymer durch Stöße auf die Membran ausübt, führt dazu, dass sich die Membran vom Polymer weg krümmt. Die resultierende Membranform ist ein Kegel in der Nähe des Ankers und ein Katenoid in grossem Abstand vom Ankerpunkt. Monte Carlo-Simulationen best

  9. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

  10. A phenomenological constitutive model for low density polyurethane foams

    SciTech Connect

    Neilsen, M.K.; Morgan, H.S.; Krieg, R.D.

    1987-04-01

    Results from a series of hydrostatic and triaxial compression tests which were performed on polyurethane foams are presented in this report. These tests indicate that the volumetric and deviatoric parts of the foam behavior are strongly coupled. This coupling behavior could not be captured with any of several commonly used plasticity models. Thus, a new constitutive model was developed. This new model was based on a decomposition of the foam response into two parts: (1) response of the polymer skeleton, and (2) response of the air inside the cells. The air contribution was completely volumetric. The new constitutive model was implemented in two finite element codes, SANCHO and PRONTO. Results from a series of analyses completed with these codes indicated that the new constitutive model captured all of the foam behaviors that had been observed in the experiments. Finally, a typical dynamic problem was analyzed using the new constitutive model and other constitutive models to demonstrate differences between the models. Results from this series of analyses indicated that the new constitutive model generated displacement and acceleration predictions that were between predictions obtained using the other models. This result was expected. 9 refs., 45 figs., 4 tabs.

  11. Constitutive modeling for isotropic materials

    NASA Technical Reports Server (NTRS)

    Lindholm, Ulric S.

    1985-01-01

    The objective is to develop a unified constitutive model for finite element structural analysis of turbine engine hot-section components. This effort constitutes a different approach for non-linear finite-element computer codes which have heretofore been based on classical inelastic methods. The unified constitutive theory to be developed will avoid the simplifying assumptions of classical theory and should more accurately represent the behavior of superalloy materials under cyclic loading conditions and high temperature environments. During the first two years of the program, extensive experimental correlations were made with two representative unified models. The experiments were both uniaxial and biaxial at temperatures up to 1093 C (2000 F). In addition, the unified models were adopted to the MARC finite element code and used for stress analysis of notched bar and turbine blade geometries.

  12. High-temperature constitutive modeling

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.; Ellis, J. R.

    1984-01-01

    Thermomechanical service conditions for high-temperature levels, thermal transients, and mechanical loads severe enough to cause measurable inelastic deformation are studied. Structural analysis in support of the design of high-temperature components depends strongly on accurate mathematical representations of the nonlinear, hereditary, inelastic behavior of structural alloys at high temperature, particularly in the relatively small strain range. Progress is discussed in the following areas: multiaxial experimentation to provide a basis for high-temperature multiaxial constitutive relationships; nonisothermal testing and theoretical development toward a complete thermomechanically path dependent formulation of viscoplasticity; and development of viscoplastic constitutive model accounting for initial anisotropy.

  13. Polymer therapeutics: concepts and applications.

    PubMed

    Haag, Rainer; Kratz, Felix

    2006-02-13

    Polymer therapeutics encompass polymer-protein conjugates, drug-polymer conjugates, and supramolecular drug-delivery systems. Numerous polymer-protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer-protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low-molecular-weight anticancer drugs to high-molecular-weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N-(2-hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug-delivery systems based on well-defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core-shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug-delivery systems.

  14. A Venture in Constitutional Law.

    ERIC Educational Resources Information Center

    Cole, W. Graham; Dillon, Dorothy H.

    1980-01-01

    Senior high girls and boys from two single-sex schools undertook a study of a Supreme Court case that provided insight not only into constitutional law and history but also into how men and women can work together and relate in other ways than dating. (DS)

  15. Take Advantage of Constitution Day

    ERIC Educational Resources Information Center

    McCune, Bonnie F.

    2008-01-01

    The announcement of the mandate for Constitution and Citizenship Day shortly before September, 2005, probably led to groans of dismay. Not another "must-do" for teachers and schools already stressed by federal and state requirements for standardized tests, increasingly rigid curricula, and scrutiny from the public and officials. But the…

  16. The Constitution and Academic Freedom.

    ERIC Educational Resources Information Center

    Gilbertson, Eric R.

    During the past 150 years U.S. courts have demonstrated a special protectiveness toward academics and academic institutions. Academic freedom was not a concern when the U.S. Constitution and the First Amendment were drafted and is not mentioned in the "Federalist Papers." However, decisions by a series of Supreme Court justices led to…

  17. The Geography behind the Constitution.

    ERIC Educational Resources Information Center

    Salter, Christopher L.; Hobbs, Gail L.

    1988-01-01

    Examines some of the geographical elements that influenced the creation of the U.S. Constitution, such as sectionalism, the Piedmont, and the Atlantic Coastal Plain. Focusing on aspects of geography that underlie the thinking, writing, and ratification of the document, the authors explore geography as environment, image-maker, and explicit…

  18. Take Advantage of Constitution Day

    ERIC Educational Resources Information Center

    McCune, Bonnie F.

    2008-01-01

    The announcement of the mandate for Constitution and Citizenship Day shortly before September, 2005, probably led to groans of dismay. Not another "must-do" for teachers and schools already stressed by federal and state requirements for standardized tests, increasingly rigid curricula, and scrutiny from the public and officials. But the…

  19. Simulations of Polymer Translocation

    NASA Astrophysics Data System (ADS)

    Vocks, H.

    2008-07-01

    Transport of molecules across membranes is an essential mechanism for life processes. These molecules are often long, and the pores in the membranes are too narrow for the molecules to pass through as a single unit. In such circumstances, the molecules have to squeeze -- i.e., translocate -- themselves through the pores. DNA, RNA and proteins are such naturally occuring long molecules in a variety of biological processes. Understandably, the process of translocation has been an active topic of current research: not only because it is a cornerstone of many biological processes, but also due to its relevance for practical applications. Translocation is a complicated process in living organisms -- the presence of chaperone molecules, pH, chemical potential gradients, and assisting molecular motors strongly influence its dynamics. Consequently, the translocation process has been empirically studied in great variety in biological literature. Study of translocation as a biophysical process is more recent. Herein, the polymer is simplified to a sequentially connected string of N monomers as it passes through a narrow pore on a membrane. The quantities of interest are the typical time scale for the polymer to leave a confining cell (the ``escape of a polymer from a vesicle'' time scale), and the typical time scale the polymer spends in the pore (the ``dwell'' time scale) as a function of N and other parameters like membrane thickness, membrane adsorption, electrochemical potential gradient, etc. Our research is focused on computer simulations of translocation. Since our main interest is in the scaling properties, we use a highly simplified description of the translocation process. The polymer is described as a self-avoiding walk on a lattice, and its dynamics consists of single-monomer jumps from one lattice site to another neighboring one. Since we have a very efficient program to simulate such polymer dynamics, which we decribe in Chapter 2, we can perform long

  20. Synthetic Polymers from Readily Available Monosaccharides

    NASA Astrophysics Data System (ADS)

    Galbis, J. A.; García-Martín, M. G.

    The low degradability of petroleum-based polymers and the massive use of these materials constitute a serious problem because of the environmental pollution that they can cause. Thus, sustained efforts have been extensively devoted to produce new polymers based on natural renewing resources and with higher degradability. Of the different natural sources, carbohydrates stand out as highly convenient raw materials because they are inexpensive, readily available, and provide great stereochemical diversity. New polymers, analogous to the more accredited technical polymers, but based on chiral monomers, have been synthesized from natural and available sugars. This chapter describes the potential of sugar-based monomers as precursors to a wide variety of macromolecular materials.

  1. Polymer adsorption

    NASA Astrophysics Data System (ADS)

    Joanny, Jean-Francois

    2008-03-01

    The aim of this talk is to review Pierre-Gilles deGennes' work on polymer adsorption and the impact that it has now in our understanding of this problem. We will first present the self-consistent mean-field theory and its applications to adsorption and depletion. De Gennes most important contribution is probably the derivation of the self-similar power law density profile for adsorbed polymer layers that we will present next, emphasizing the differences between the tail sections and the loop sections of the adsorbed polymers. We will then discuss the kinetics of polymer adsorption and the penetration of a new polymer chain in an adsobed layer that DeGennes described very elegantly in analogy with a quantum tunneling problem. Finally, we will discuss the role of polymer adsorption for colloid stabilization.

  2. [Women, gender, and the Constitution].

    PubMed

    1993-12-01

    Although all the constitutions of Latin America directly or indirectly acknowledge the juridical equality of the sexes, these patriarchal societies continue to maintain institutional power in male hands and to neutralize legal actions favoring women. International instruments such as the Convention on Elimination of All Forms of Discrimination Against Women, approved by the UN in 1979, have given a firmer basis to policies and actions to improve the status of women. Obstacles to full equality of Latin American women are rooted in economic and sociopolitical factors, but lack of true political will also plays a significant role. A number of new laws in the past several years as well as the new Constitution have improved the legal position of Colombian women. The new Constitution recognizes fundamental rights that may be claimed directly before a judge, and social, economic, and collective rights requiring legislative development. Article 43 of the new Constitution states that women will not be subjected to any form of discrimination. Another norm states that women will enjoy special assistance and protection before and after childbirth, in recognition of the social functions of maternity. Article 43 also states that women who are heads of households will receive special assistance, but the corresponding regulations have not yet been promulgated. The mechanism of tutelage has become an important recourse that has been used in several cases in which fundamental rights of women have been violated or threatened because of their sex. The order of tutelage has been used in cases of adolescents expelled from school for pregnancy and of abused wives, as well as to force recognition of the social and economic contributions of housework.

  3. Biomimetic polymers responsive to a biological signaling molecule: nitric oxide triggered reversible self-assembly of single macromolecular chains into nanoparticles.

    PubMed

    Hu, Jinming; Whittaker, Michael R; Duong, Hien; Li, Yang; Boyer, Cyrille; Davis, Thomas P

    2014-07-21

    Novel nitric oxide (NO) responsive monomers (NAPMA and APUEMA) containing o-phenylenediamine functional groups have been polymerized to form NO-responsive macromolecular chains as truly biomimetic polymers. Upon exposure to NO--a ubiquitous cellular signaling molecule--the NAPMA- and APUEMA-labeled thermoresponsive copolymers exhibited substantial changes in solubility, clearly characterized by tuneable LCST behavior, thereby inducing self-assembly into nanoparticulate structures. Moreover, the NO-triggered self-assembly process in combination with environmentally sensitive fluorescence dyes could be employed to detect and image endogenous NO.

  4. Constitutive modelling of composite biopolymer networks.

    PubMed

    Fallqvist, B; Kroon, M

    2016-04-21

    The mechanical behaviour of biopolymer networks is to a large extent determined at a microstructural level where the characteristics of individual filaments and the interactions between them determine the response at a macroscopic level. Phenomena such as viscoelasticity and strain-hardening followed by strain-softening are observed experimentally in these networks, often due to microstructural changes (such as filament sliding, rupture and cross-link debonding). Further, composite structures can also be formed with vastly different mechanical properties as compared to the individual networks. In this present paper, we present a constitutive model presented in a continuum framework aimed at capturing these effects. Special care is taken to formulate thermodynamically consistent evolution laws for dissipative effects. This model, incorporating possible anisotropic network properties, is based on a strain energy function, split into an isochoric and a volumetric part. Generalisation to three dimensions is performed by numerical integration over the unit sphere. Model predictions indicate that the constitutive model is well able to predict the elastic and viscoelastic response of biological networks, and to an extent also composite structures.

  5. A constitutive model of nanocomposite hydrogels with nanoparticle crosslinkers

    NASA Astrophysics Data System (ADS)

    Wang, Qiming; Gao, Zheming

    2016-09-01

    Nanocomposite hydrogels with only nanoparticle crosslinkers exhibit extraordinarily higher stretchability and toughness than the conventional organically crosslinked hydrogels, thus showing great potential in the applications of artificial muscles and cartilages. Despite their potential, the microscopic mechanics details underlying their mechanical performance have remained largely elusive. Here, we develop a constitutive model of the nanoparticle hydrogels to elucidate the microscopic mechanics behaviors, including the microarchitecture and evolution of the nanoparticle crosslinked polymer chains during the mechanical deformation. The constitutive model enables us to understand the Mullins effect of the nanocomposite hydrogels, and the effects of nanoparticle concentrations and sizes on their cyclic stress-strain behaviors. The theory is quantitatively validated by the tensile tests on a nanocomposite hydrogel with nanosilica crosslinkers. The theory can also be extended to explain the mechanical behaviors of existing hydrogels with nanoclay crosslinkers, and the necking instability of the composite hydrogels with both nanoparticle crosslinkers and organic crosslinkers. We expect that this constitutive model can be further exploited to reveal mechanics behaviors of novel particle-polymer chain interactions, and to design unprecedented hydrogels with both high stretchability and toughness.

  6. Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    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.

  7. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    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.

  8. Constitutive modeling for isotropic materials

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.

    1988-01-01

    The third and fourth years of a 4-year research program, part of the NASA HOST Program, are described. The program goals were: (1) to develop and validate unified constitutive models for isotropic materials, and (2) to demonstrate their usefulness for structural analysis of hot section components of gas turbine engines. The unified models selected for development and evaluation were those of Bodner-Partom and of Walker. The unified approach for elastic-viscoplastic constitutive equations is a viable method for representing and predicting material response characteristics in the range where strain rate and temperature dependent inelastic deformations are experienced. This conclusion is reached by extensive comparison of model calculations against the experimental results of a test program of two high temperature Ni-base alloys, B1900+Hf and Mar-M247, over a wide temperature range for a variety of deformation and thermal histories including uniaxial, multiaxial, and thermomechanical loading paths. The applicability of the Bodner-Partom and the Walker models for structural applications has been demonstrated by implementing these models into the MARC finite element code and by performing a number of analyses including thermomechanical histories on components of hot sections of gas turbine engines and benchmark notch tensile specimens. The results of the 4-year program have been published in four annual reports. The results of the base program are summarized in this report. The tasks covered include: (1) development of material test procedures, (2) thermal history effects, and (3) verification of the constitutive model for an alternative material.

  9. Macromolecular recognition: Recognition of polymer side chains by cyclodextrin

    NASA Astrophysics Data System (ADS)

    Hashidzume, Akihito; Harada, Akira

    2015-12-01

    The interaction of cyclodextrins (CD) with water soluble polymers possessing guest residues has been investigated as model systems in biological molecular recognition. The selectivity of interaction of CD with polymer-carrying guest residues is controlled by polymer chains, i.e., the steric effect of polymer main chain, the conformational effect of polymer main chain, and multi-site interaction. Macroscopic assemblies have been also realized based on molecular recognition using polyacrylamide-based gels possessing CD and guest residues.

  10. A new restricted access molecularly imprinted polymer capped with albumin for direct extraction of drugs from biological matrices: the case of chlorpromazine in human plasma.

    PubMed

    de Oliveira Isac Moraes, Gabriel; da Silva, Larissa Meirelles Rodrigues; dos Santos-Neto, Alvaro José; Florenzano, Fábio Herbst; Figueiredo, Eduardo Costa

    2013-09-01

    A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA) was developed, characterized, and used for direct analysis of chlorpromazine in human plasma samples. The RAMIP-BSA was synthesized using chlorpromazine, methacrylic acid, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Glycerol dimethacrylate and hydroxy methyl methacrylate were used to promote a hydrophilic surface (high density of hydroxyl groups). Afterward, the polymer was coated with BSA using glutaraldehyde as cross-linker, resulting in a protein chemical shield around it. The material was able to eliminate ca. 99% of protein when a 44-mg mL(-1) BSA aqueous solution was passed through it. The RAMIP-BSA was packed in a column and used for direct analysis of chlorpromazine in human plasma samples in an online column switching high-performance liquid chromatography system. The analytical calibration curve was prepared in a pool of human plasma samples with chlorpromazine concentrations ranging from 30 to 350 μg L(-1). The correlation coefficient obtained was 0.995 and the limit of quantification was 30 μg L(-1). Intra-day and inter-day precision and accuracy presented variation coefficients and relative errors lower than 15% and within -15 and 15%, respectively. The sample throughput was 3 h(-1) (sample preparation and chromatographic analysis steps) and the same RAMIP-BSA column was efficiently used for about 90 cycles.

  11. The Constitution: Perspectives on Contemporary American Democracy.

    ERIC Educational Resources Information Center

    Close Up Foundation, Arlington, VA.

    Four articles expressing the views of nine prominent United States citizens about the Constitution provide a context for reflecting on the meaning of the Constitution in present-day America. In "Why Has the Constitution Endured So Long?" Don Edwards, chairman of the House Civil and Constitutional Rights Subcommittee, discusses why the…

  12. 32 CFR 536.42 - Constitutional torts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Constitutional torts. 536.42 Section 536.42... AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable under...

  13. Constitution-Writing in Central Europe.

    ERIC Educational Resources Information Center

    Troy, Daniel E.

    1990-01-01

    Remarks on experiences as a participant at a conference on constitution-writing that linked Czech and Slovak constitution writers with U.S. lawyers. Argues cultural traditions must be respected when advising how to write constitutions. Examines challenges facing Czech and Slovak constitution writers, including structuring the government; the…

  14. Polymers & People

    ERIC Educational Resources Information Center

    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…

  15. Polymers & People

    ERIC Educational Resources Information Center

    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…

  16. What constitutes a community placement?

    PubMed

    Temple, Jenny

    When developing pre-registration adult nursing programmes, education providers in both educational institutions and clinical areas must decide what is a community nursing placement and how much time students should spend there. This article considers definitions of what constitutes "community" in terms of clinical placements for student nurses. It suggests what might realistically be termed community nursing and home nursing and explains how these can enrich student nurses' experiences. The practice requirements for other pre-registration nursing fields, such as child, mental health and learning disabilities, have not been considered here, although some of the discussion would be relevant to these areas.

  17. A novel one-dimensional manganese(II) coordination polymer containing both dicyanamide and pyrazinamide ligands: Synthesis, spectroscopic investigations, X-ray studies and evaluation of biological activities

    NASA Astrophysics Data System (ADS)

    Tabrizi, Leila; Chiniforoshan, Hossein; McArdle, Patrick

    2015-03-01

    A novel 1D coordination polymer {[Mn(μ1,5-dca)2(PZA)2](PZA)2}n, 1, has been synthesized and characterized by single crystal X-ray crystallography. The coordination mode of dicyanamide (dca) and pyrazinamide (PZA) ligands was inferred by IR spectroscopy. The compound 1 was evaluated for in vitro antimycobacterial and antitumor activities. It demonstrated better in vitro activity against Mycobacterium tuberculosis than pyrazinamide and its MIC value was determined. Complex 1 was also screened for its in vitro antitumor activity towards LM3 and LP07 murine cancer cell lines. In addition, the antibacterial activity of complex 1 has been tested against Gram(+) and Gram(-) bacteria and it has shown promising broad range anti-bacterial activity.

  18. A novel solid fluorescence method for the fast determination of quercetin in biological samples based on the quercetin-Al(III) complex imprinted polymer

    NASA Astrophysics Data System (ADS)

    Hu, Yufei; Feng, Ting; Li, Gongke

    2014-01-01

    In this work, a novel solid fluorescence method was proposed and applied to the fast determination of quercetin in urine and onion skin samples by using metal coordination imprinted polymer membrane, which was regarded as a recognition element. The quercetin-Al(III) imprinted polymer was immobilized in the microporous polypropylene fiber membrane via consecutive in situ polymerization. The CIP membrane had the porous, loose and layer upon layer structure. The CIP membrane was characterized by electron microscope photographs, infrared spectra, thermogravimetric analysis and solvent-resistant investigation. The extraction conditions including extraction solvent, extraction time, desorption solvent were optimized. Compared with MIP and NIP membrane, CIP membrane had been proved to be peculiar selective for quercetin even in presence of the structurally similar compounds such as kaempferol, rutin, naringenin and alpinetin. The CIP membrane was characteristic of high selectivity, stable and sensitive response to quercetin in polar environment. Under the optimum condition, there was a linear relationship between the state fluorescent response and the concentration of quercetin. The linear calibration range was over 0.02 mg L-1-0.80 mg L-1 with a detection limit of 5 μg L-1. The method was characteristic of flexible and good repeatability with relative standard deviation (RSD) of 4.1%. The proposed method was also successfully applied for the determination of quercetin in urine and onion skin samples without complicated pretreatment. The recoveries were 84.0-112.4% and RSDs varied from 1.5% to 6.8%. The results obtained by the proposed method agreed well with those obtained by HPLC method.

  19. Backward-mode multiwavelength photoacoustic scanner using a planar Fabry-Perot polymer film ultrasound sensor for high-resolution three-dimensional imaging of biological tissues.

    PubMed

    Zhang, Edward; Laufer, Jan; Beard, Paul

    2008-02-01

    A multiwavelength backward-mode planar photoacoustic scanner for 3D imaging of soft tissues to depths of several millimeters with a spatial resolution in the tens to hundreds of micrometers range is described. The system comprises a tunable optical parametric oscillator laser system that provides nanosecond laser pulses between 600 and 1200 nm for generating the photoacoustic signals and an optical ultrasound mapping system based upon a Fabry-Perot polymer film sensor for detecting them. The system enables photoacoustic signals to be mapped in 2D over a 50 mm diameter aperture in steps of 10 microm with an optically defined element size of 64 microm. Two sensors were used, one with a 22 microm thick polymer film spacer and the other with a 38 mum thick spacer providing -3 dB acoustic bandwidths of 39 and 22 MHz, respectively. The measured noise equivalent pressure of the 38 microm sensor was 0.21 kPa over a 20 MHz measurement bandwidth. The instrument line-spread function (LSF) was measured as a function of position and the minimum lateral and vertical LSFs found to be 38 and 15 microm, respectively. To demonstrate the ability of the system to provide high-resolution 3D images, a range of absorbing objects were imaged. Among these was a blood vessel phantom that comprised a network of blood filled tubes of diameters ranging from 62 to 300 microm immersed in an optically scattering liquid. In addition, to demonstrate the applicability of the system to spectroscopic imaging, a phantom comprising tubes filled with dyes of different spectral characteristics was imaged at a range of wavelengths. It is considered that this type of instrument may provide a practicable alternative to piezoelectric-based photoacoustic systems for high-resolution structural and functional imaging of the skin microvasculature and other superficial structures.

  20. Effects of Cholesterol Incorporation on the Physicochemical, Colloidal, and Biological Characteristics of pH-sensitive AB2 Miktoarm Polymer-Based Polymersomes

    PubMed Central

    Yin, Haiqing; Kang, Han Chang; Huh, Kang Moo; Bae, You Han

    2014-01-01

    In our previous study, a histidine-based AB2 miktoarm polymer, methoxy poly(ethylene glycol)-b-poly(l-histidine)2 (mPEG-b-(PolyHis)2), was designed to construct pH-sensitive polymersomes that transform in acidic pH; the polymer self-assembles into a structure that mimics phospholipids. In this study, the polymersomes further imitated liposomes due to the incorporation of cholesterol (CL). The hydrodynamic radii of the polymersomes increased with increasing CL wt% (e.g., 70 nm for 0 wt% vs. 91 nm for 1 wt%), resulting in an increased capacity for encapsulating hydrophilic drugs (e.g., 0.92 µL/mg for 0 wt% vs. 1.42 µL/mg for 1 wt%). The CL incorporation enhanced the colloidal stability of the polymersomes in the presence of serum protein and retarded their payload release. However, CL-incorporating polymersomes still demonstrated accelerated release of a hydrophilic dye (e.g., 5(6)-carboxyfluorescein (CF)) below pH 6.8 without losing their desirable pH sensitivity. CF-loaded CL-incorporating polymersomes showed better cellular internalization than the hydrophilic CF, whereas doxorubicin (DOX)-loaded CL-incorporating polymersomes presented similar or somewhat lower anti-tumor effects than free hydrophobic DOX. The findings suggest that CL-incorporating mPEG-b-(PolyHis)2-based polymersomes may have potential for intracellular drug delivery of chemical drugs due to their improved colloidal stability, lower drug loss during circulation, acidic pH-induced drug release, and endosomal disruption. PMID:24463148

  1. Mesoscale constitutive modeling of non-crystallizing filled elastomers

    NASA Astrophysics Data System (ADS)

    Harish, Ajay B.; Wriggers, Peter; Jungk, Juliane; Hojdis, Nils; Recker, Carla

    2016-04-01

    Elastomers are exceptional materials owing to their ability to undergo large deformations before failure. However, due to their very low stiffness, they are not always suitable for industrial applications. Addition of filler particles provides reinforcing effects and thus enhances the material properties that render them more versatile for applications like tyres etc. However, deformation behavior of filled polymers is accompanied by several nonlinear effects like Mullins and Payne effect. To this day, the physical and chemical changes resulting in such nonlinear effect remain an active area of research. In this work, we develop a heterogeneous (or multiphase) constitutive model at the mesoscale explicitly considering filler particle aggregates, elastomeric matrix and their mechanical interaction through an approximate interface layer. The developed constitutive model is used to demonstrate cluster breakage, also, as one of the possible sources for Mullins effect observed in non-crystallizing filled elastomers.

  2. Constitutive modeling for isotropic materials

    NASA Technical Reports Server (NTRS)

    Lindholm, Ulric S.; Chan, Kwai S.

    1986-01-01

    The objective of the program is to evaluate and develop existing constitutive models for use in finite-element structural analysis of turbine engine hot section components. The class of constitutive equation studied is considered unified in that all inelastic deformation including plasticity, creep, and stress relaxation are treated in a single term rather than a classical separation of plasticity (time independent) and creep (time dependent) behavior. The unified theories employed also do not utilize the classical yield surface or plastic potential concept. The models are constructed from an appropriate flow law, a scalar kinetic relation between strain rate, temperature and stress, and evolutionary equations for internal variables describing strain or work hardening, both isotropic and directional (kinematic). This and other studies have shown that the unified approach is particularly suited for determining the cyclic behavior of superalloy type blade and vane materials and is entirely compatible with three-dimensional inelastic finite-element formulations. The behavior was examined of a second nickel-base alloy, MAR-M247, and compared it with the Bodner-Partom model, further examined procedures for determining the material-specific constants in the models, and exercised the MARC code for a turbine blade under simulated flight spectrum loading. Results are summarized.

  3. Sasang Constitutional Medicine as a Holistic Tailored Medicine

    PubMed Central

    Pham, Duong Duc

    2009-01-01

    Sasang constitutional medicine (SCM) is a unique traditional Korean therapeutic alternative form of medicine. Based on the Yin and Yang theory and on Confucianism, humans are classified into four constitutions. These differ in terms of (i) sensitivity to certain groups of herbs and medicines, (ii) equilibrium among internal organic functions, (iii) physical features and (iv) psychological characteristics. We propose that two main axes in the physiopathology of SCM (food intake/waste discharge and consuming/storing Qi and body fluids) are equivalent to the process of internal–external exchange and catabolism/anabolism in modern physiology, respectively. We then used this hypothesis to discuss the physiological and pathological principles of SCM. Constitution-based medicine is based on the theory that some medicinal herbs and remedies are only appropriate for certain constitutions and can cause adverse effects in others. The constitutional approach of SCM share the same vision as tailored medicine; an individualized therapy that can minimize the risk of adverse reaction while increasing the efficacy and an individualized self-regulation that can help prevent specific susceptible chronic disease and live healthily. There is still a long way to this goal for both SCM and tailored medicine, but we may benefit from systems approaches such as systems biology. We suggest that constitutional perspective of SCM and our hypothesis of two main processes may provide a novel insight for further studies. PMID:19745007

  4. Unborn children as constitutional persons.

    PubMed

    Roden, Gregory J

    2010-01-01

    In Roe v. Wade, the state of Texas argued that "the fetus is a 'person' within the language and meaning of the Fourteenth Amendment." To which Justice Harry Blackmun responded, "If this suggestion of personhood is established, the appellant's case, of course, collapses, for the fetus' right to life would then be guaranteed specifically by the Amendment." However, Justice Blackmun then came to the conclusion "that the word 'person,' as used in the Fourteenth Amendment, does not include the unborn." In this article, it is argued that unborn children are indeed "persons" within the language and meaning of the Fourteenth and Fifth Amendments. As there is no constitutional text explicitly holding unborn children to be, or not to be, "persons," this argument will be based on the "historical understanding and practice, the structure of the Constitution, and thejurisprudence of [the Supreme] Court." Specifically, it is argued that the Constitution does not confer upon the federal government a specifically enumerated power to grant or deny "personhood" under the Fourteenth Amendment. Rather, the power to recognize or deny unborn children as the holders of rights and duties has been historically exercised by the states. The Roe opinion and other Supreme Court cases implicitly recognize this function of state sovereignty. The states did exercise this power and held unborn children to be persons under the property, tort, and criminal law of the several states at the time Roe was decided. As an effect of the unanimity of the states in holding unborn children to be persons under criminal, tort, and property law, the text of the Equal Protection Clause of the Fourteenth Amendment compels federal protection of unborn persons. Furthermore, to the extent Justice Blackmun examined the substantive law in these disciplines, his findings are clearly erroneous and as a whole amount to judicial error. Moreover, as a matter of procedure, according to the due process standards recognized in

  5. A Self-Assembled Aggregate Composed of a Fatty Acid Membrane and the Building Blocks of Biological Polymers Provides a First Step in the Emergence of Protocells

    PubMed Central

    Black, Roy A.; Blosser, Matthew C.

    2016-01-01

    We propose that the first step in the origin of cellular life on Earth was the self-assembly of fatty acids with the building blocks of RNA and protein, resulting in a stable aggregate. This scheme provides explanations for the selection and concentration of the prebiotic components of cells; the stabilization and growth of early membranes; the catalysis of biopolymer synthesis; and the co-localization of membranes, RNA and protein. In this article, we review the evidence and rationale for the formation of the proposed aggregate: (i) the well-established phenomenon of self-assembly of fatty acids to form vesicles; (ii) our published evidence that nucleobases and sugars bind to and stabilize such vesicles; and (iii) the reasons why amino acids likely do so as well. We then explain how the conformational constraints and altered chemical environment due to binding of the components to the membrane could facilitate the formation of nucleosides, oligonucleotides and peptides. We conclude by discussing how the resulting oligomers, even if short and random, could have increased vesicle stability and growth more than their building blocks did, and how competition among these vesicles could have led to longer polymers with complex functions. PMID:27529283

  6. Validation of weak biological effects by round robin experiments: cytotoxicity/biocompatibility of SiO2 and polymer nanoparticles in HepG2 cells.

    PubMed

    Landgraf, Lisa; Nordmeyer, Daniel; Schmiel, Peter; Gao, Qi; Ritz, Sandra; S Gebauer, Julia; Graß, Stefan; Diabaté, Silvia; Treuel, Lennart; Graf, Christina; Rühl, Eckart; Landfester, Katharina; Mailänder, Volker; Weiss, Carsten; Zellner, Reinhard; Hilger, Ingrid

    2017-06-28

    All over the world, different types of nanomaterials with a diversified spectrum of applications are designed and developed, especially in the field of nanomedicine. The great variety of nanoparticles (NPs), in vitro test systems and cell lines led to a vast amount of publications with conflicting data. To identify the decisive principles of these variabilities, we conducted an intercomparison study of collaborating laboratories within the German DFG Priority Program SPP1313, using well-defined experimental parameters and well-characterized NPs. The participants analyzed the in vitro biocompatibility of silica and polymer NPs on human hepatoma HepG2 cells. Nanoparticle mediated effects on cell metabolism, internalization, and inflammation were measured. All laboratories showed that both nanoparticle formulations were internalized and had a low cytotoxicity profile. Interestingly, small variations in nanoparticle preparation, cell handling and the type of culture slide influenced the nanoparticle stability and the outcomes of cell assays. The round robin test demonstrated the importance of the use of clearly defined and characterized NPs and parameters for reproducible results across laboratories. Comparative analyses of in vitro screening methods performed in multiple laboratories are absolutely essential to establish robust standard operation procedure as a prerequisite for sound hazard assessment of nanomaterials.

  7. Monolithic molecular imprinted polymer fiber for recognition and solid phase microextraction of ephedrine and pseudoephedrine in biological samples prior to capillary electrophoresis analysis.

    PubMed

    Deng, Dong-Li; Zhang, Ji-You; Chen, Chen; Hou, Xiao-Ling; Su, Ying-Ying; Wu, Lan

    2012-01-06

    A novel capillary electrophoresis (CE) method coupled with monolithic molecular imprinted polymer (MIP) fiber based solid phase microextraction (SPME) was developed for selective and sensitive determination of ephedrine (E) and pseudoephedrine (PE). With in situ polymerization in a silica capillary mold and E as template, the MIP fibers could be produced in batch reproducibly and each fiber was available for 50 extraction cycles without significant decrease in extraction ability. Using the MIP fiber under optimized extraction conditions, CE detection limits of E and PE were greatly lowered from 0.20 to 0.00096 μg/mL and 0.12 to 0.0011 μg/mL, respectively. Analysis of urine and serum samples by the MIP-SPME-CE method was also performed, with results indicating that E and PE could be selectively extracted. The recoveries and relative standard deviations (RSDs) for sample analysis were found in the range of 91-104% and 3.8-9.1%, respectively.

  8. Polymer flooding

    SciTech Connect

    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.

  9. Semiconducting polymers

    NASA Astrophysics Data System (ADS)

    Hermann, A. M.

    A review is presented of the electrical properties of those polymers whose conductivities occupy the middle ground between polymeric insulators and polymeric superconductors. Attention is confined to polymers in which conduction occurs through electronic, rather than ionic, transport. Four classes of semiconductors are discussed: (1) highly-conjugated polymers, including those formed by pyrolysis; (2) polymeric charge-transfer complexes and radical-ion salts; (3) organometallic polymeric semiconductors; and (4) composite polymer systems containing carbon or other highly conducting media. The possible applications discussed include cathodes in solid-state metal/halogen primary batteries, cathodes in lithium/poly-p-phenylene or polyacetylene secondary batteries, conductive coatings and epoxies, and chemical sensing agents. Other applications are Peltier cooling devices, pressure transducers, photovoltaic devices, infrared radiation detectors, and switches and resistors.

  10. Organometallic Polymers.

    ERIC Educational Resources Information Center

    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)

  11. Polymers All Around You!

    ERIC Educational Resources Information Center

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers…

  12. Polymers All Around You!

    ERIC Educational Resources Information Center

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers…

  13. New constitutionalism and the social reproduction of caring institutions.

    PubMed

    Gill, Stephen; Bakker, Isabella

    2006-01-01

    This essay analyzes neo-liberal economic agreements and legal and political frameworks or what has been called the "new constitutionalism," a governance framework that empowers market forces to reshape economic and social development worldwide. The article highlights some consequences of new constitutionalism for caring institutions specifically, and for what feminists call social reproduction more generally: the biological reproduction of the species; the reproduction of labor power; and the reproduction of social institutions and processes associated with the creation and maintenance of communities. New constitutional governance frameworks fundamentally reshape conditions under which the care of human beings takes place. Caring institutions once governed by enabling professions geared to universal care are now determined increasingly by market values and private forces, and driven directly by the profit motive. This is one of the reasons why neo-liberalism is increasingly contested in both the North and the global South.

  14. On the Constitutive Response Characterization for Composite Materials Via Data-Driven Design Optimization

    Treesearch

    John G. Michopoulos; John G. Hermanson; Athanasios lliopoulos; Samuel Lambrakos; Tomonari Furukawa

    2011-01-01

    In the present paper we focus on demonstrating the use of design optimization for the constitutive characterization of anisotropic material systems such as polymer matrix composites, with or without damage. All approaches are based on the availability of experimental data originating from mechatronic material testing systems that can expose specimens to...

  15. 17 CFR 200.54 - Constitutional obligations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... ORGANIZATION; CONDUCT AND ETHICS; AND INFORMATION AND REQUESTS Canons of Ethics § 200.54 Constitutional... Constitution. Insofar as the enactments of the Congress impose executive duties upon the members, they must...

  16. Native Communities and the Peruvian Constitutional Assembly

    ERIC Educational Resources Information Center

    American Indian Journal, 1978

    1978-01-01

    A loosely knit coalition of over 25 native groups, the Peruvian Amazon Peoples has prepared a statement directed at the Peruvian Constitutional Assembly for purposes of Native input into the preparation of a revised national constitution. (JC)

  17. Written Constitution or None: Which Works Better?

    ERIC Educational Resources Information Center

    Cowen, Zelman

    1987-01-01

    Explores the differences between the U.S. Constitution and British constitutional law. Specifically examines the concept of the U.S. Bill of Rights in relation to the United Kingdom common law doctrine of parliamentary sovereignty. (BSR)

  18. An effective polymer cross-linking strategy to obtain stable dispersions of upconverting NaYF4 nanoparticles in buffers and biological growth media for biolabeling applications.

    PubMed

    Jiang, Guicheng; Pichaandi, Jothirmayanantham; Johnson, Noah J J; Burke, Robert D; van Veggel, Frank C J M

    2012-02-14

    Ligands on the nanoparticle surface provide steric stabilization, resulting in good dispersion stability. However, because of their highly dynamic nature, they can be replaced irreversibly in buffers and biological medium, leading to poor colloidal stability. To overcome this, we report a simple and effective cross-linking methodology to transfer oleate-stabilized upconverting NaYF(4) core/shell nanoparticles (UCNPs) from hydrophobic to aqueous phase, with long-term dispersion stability in buffers and biological medium. Amphiphilic poly(maleic anhydride-alt-1-octadecene) (PMAO) modified with and without poly(ethylene glycol) (PEG) was used to intercalate with the surface oleates, enabling the transfer of the UCNPs to water. The PMAO units on the phase transferred UCNPs were then successfully cross-linked using bis(hexamethylene)triamine (BHMT). The primary advantage of cross-linking of PMAO by BHMT is that it improves the stability of the UCNPs in water, physiological saline buffers, and biological growth media and in a wide range of pH values when compared to un-cross-linked PMAO. The cross-linked PMAO-BHMT coated UCNPs were found to be stable in water for more than 2 months and in physiological saline buffers for weeks, substantiating the effectiveness of cross-linking in providing high dispersion stability. The PMAO-BHMT cross-linked UCNPs were extensively characterized using various techniques providing supporting evidence for the cross-linking process. These UCNPs were found to be stable in serum supplemented growth medium (37 °C) for more than 2 days. Utilizing this, we demonstrate the uptake of cross-linked UCNPs by LNCaP cells (human prostate cancer cell line), showing their utility as biolabels.

  19. Constitutive Behavior and Finite Element Analysis of FRP Composite and Concrete Members

    PubMed Central

    Ann, Ki Yong; Cho, Chang-Geun

    2013-01-01

    The present study concerns compressive and flexural constitutive models incorporated into an isoparametric beam finite element scheme for fiber reinforced polymer (FRP) and concrete composites, using their multi-axial constitutive behavior. The constitutive behavior of concrete was treated in triaxial stress states as an orthotropic hypoelasticity-based formulation to determine the confinement effect of concrete from a three-dimensional failure surface in triaxial stress states. The constitutive behavior of the FRP composite was formulated from the two-dimensional classical lamination theory. To predict the flexural behavior of circular cross-section with FRP sheet and concrete composite, a layered discretization of cross-sections was incorporated into nonlinear isoparametric beam finite elements. The predicted constitutive behavior was validated by a comparison to available experimental results in the compressive and flexural beam loading test. PMID:28788312

  20. Constitutive Behavior and Finite Element Analysis of FRP Composite and Concrete Members.

    PubMed

    Ann, Ki Yong; Cho, Chang-Geun

    2013-09-10

    The present study concerns compressive and flexural constitutive models incorporated into an isoparametric beam finite element scheme for fiber reinforced polymer (FRP) and concrete composites, using their multi-axial constitutive behavior. The constitutive behavior of concrete was treated in triaxial stress states as an orthotropic hypoelasticity-based formulation to determine the confinement effect of concrete from a three-dimensional failure surface in triaxial stress states. The constitutive behavior of the FRP composite was formulated from the two-dimensional classical lamination theory. To predict the flexural behavior of circular cross-section with FRP sheet and concrete composite, a layered discretization of cross-sections was incorporated into nonlinear isoparametric beam finite elements. The predicted constitutive behavior was validated by a comparison to available experimental results in the compressive and flexural beam loading test.

  1. How Does the Constitution Secure Rights?

    ERIC Educational Resources Information Center

    Goldwin, Robert A., Ed.; Schambra, William A., Ed.

    Third in a series designed to help prepare the nation for a thoughtful observance of the Constitutional bicentennial, this publication presents six essays addressing the issue of human rights and the Constitution. "How the Constitution Protects Our Rights: A Look at the Seminal Years" (Robert A. Rutland) focuses on James Madison's role…

  2. Theoretical Issues of the Constitutional Regulation Mechanism

    ERIC Educational Resources Information Center

    Zhussupova, Guldaray B.; Zhailyaubayev, Rassul T.; Ukin, Symbat K.; Shunayeva, Sylu M.; Nurmagambetov, Rachit G.

    2016-01-01

    The purpose of this research is to define the concept of "constitutional regulation mechanism." The definition of the concept of "constitutional regulation mechanism" will give jurists and legislators a theoretical framework for developing legal sciences, such as the constitutional law and the theory of state and law. The…

  3. American Focus on World Constitutions. Teacher's Guide.

    ERIC Educational Resources Information Center

    Holmes, Stanley T., III

    This curriculum project was designed to familiarize high school students with their own constitutional roots while gaining a better understanding of governmental systems developed by other nations. The project uses the U.S. Constitution as a baseline for analyzing the constitutions of other nations, and is intended to supplement courses in such…

  4. 32 CFR 536.42 - Constitutional torts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable under... partially payable as a state tort. For example, a Fifth Amendment taking may be payable in an altered...

  5. Antithetical Ethics: Kenneth Burke and the Constitution.

    ERIC Educational Resources Information Center

    Anderson, Virginia

    1995-01-01

    Shows how the textuality of the United States Constitution, the most venerable of classic democratic icons, might be exploited to nurture postmodern ethics. Shows how Kenneth Burke's reading of the Constitution accords with and augments the postmodern theories of J.-F. Lyotard and S. Jarratt. Discusses a postmodern Constitution and the…

  6. State Constitutional Law: Teaching and Scholarship.

    ERIC Educational Resources Information Center

    Williams, Robert F.

    1991-01-01

    State constitutional law is an emerging area for legal education, partly because of state supreme court decisions relying on state rather than federal constitutional law. Studying state constitutional law highlights similarities and diversity of legal and governmental systems. Interest in establishment of curricula and materials in state law is…

  7. 32 CFR 536.42 - Constitutional torts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable under... partially payable as a state tort. For example, a Fifth Amendment taking may be payable in an altered...

  8. 32 CFR 536.42 - Constitutional torts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable under... partially payable as a state tort. For example, a Fifth Amendment taking may be payable in an altered...

  9. 32 CFR 536.42 - Constitutional torts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable under... partially payable as a state tort. For example, a Fifth Amendment taking may be payable in an altered...

  10. 29 CFR 452.18 - Constitutional officers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are not...

  11. 29 CFR 452.18 - Constitutional officers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are not...

  12. 29 CFR 452.18 - Constitutional officers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are not...

  13. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    PubMed

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  14. Constitutive model for porous materials

    SciTech Connect

    Weston, A.M.; Lee, E.L.

    1982-01-01

    A simple pressure versus porosity compaction model is developed to calculate the response of granular porous bed materials to shock impact. The model provides a scheme for calculating compaction behavior when relatively limited material data are available. While the model was developed to study porous explosives and propellants, it has been applied to a much wider range of materials. The early development of porous material models, such as that of Hermann, required empirical dynamic compaction data. Erkman and Edwards successfully applied the early theory to unreacted porous high explosives using a Gruneisen equation of state without yield behavior and without trapped gas in the pores. Butcher included viscoelastic rate dependance in pore collapse. The theoretical treatment of Carroll and Holt is centered on the collapse of a circular pore and includes radial inertia terms and a complex set of stress, strain and strain rate constitutive parameters. Unfortunately data required for these parameters are generally not available. The model described here is also centered on the collapse of a circular pore, but utilizes a simpler elastic-plastic static equilibrium pore collapse mechanism without strain rate dependence, or radial inertia terms. It does include trapped gas inside the pore, a solid material flow stress that creates both a yield point and a variation in solid material pressure with radius. The solid is described by a Mie-Gruneisen type EOS. Comparisons show that this model will accurately estimate major mechanical features which have been observed in compaction experiments.

  15. More Than Just a Polymer

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Triton atomic Oxygen Resistant polymers TOR(TM), were developed by Chelmsford, Massachusetts-based Triton Systems, Inc., through a Small Business Innovation Research (SBIR) contract from NASA's Langley Research Center. The new family of polymers comes from a Langley-developed polymer technology, which marks a new class of aerospace materials that resist the extreme effects of low Earth orbit (LEO). When applied to spacecraft surfaces, TOR polymers protect against erosion caused by the atomic oxygen and radiation present in space. Other polymers, such as Teflon(R) and Kapton(R), are subject to degradation from atomic oxygen and ultraviolet radiation, but TOR polymers use atomic oxygen to their advantage. A long-lasting protective barrier means major savings in the cost of spacecraft maintenance and the time spent performing repairs. While the obvious application of this material lies with the aerospace industry, an underlying benefit is found in the field of electronics. TOR polymers can be made electrically conductive, and then utilized in the creation of sensors that react to the presence of chemical and biological agents by exhibiting a detectable change in electrical conductivity. These sensors have applications in the defense, medical, and industrial sectors.

  16. Multifunctional and biologically active matrices from multicomponent polymeric solutions

    NASA Technical Reports Server (NTRS)

    Kiick, Kristi L. (Inventor); Yamaguchi, Nori (Inventor); Rabolt, John (Inventor); Casper, Cheryl (Inventor)

    2012-01-01

    A functionalized electrospun matrix for the controlled-release of biologically active agents, such as growth factors, is presented. The functionalized matrix comprises a matrix polymer, a compatibilizing polymer and a biomolecule or other small functioning molecule. In certain aspects the electrospun polymer fibers comprise at least one biologically active molecule functionalized with low molecular weight heparin.

  17. Constitutive Equation for Anisotropic Rock

    NASA Astrophysics Data System (ADS)

    Cazacu, O.

    2006-12-01

    In many rocks, due to the existence of well-defined fabric elements such as bedding, layering, foliation or lamination planes, or due to the existence of linear structures, anisotropy can be important. The symmetries most frequently encountered are: transverse isotropy and orthotropy. By adopting both theoretical and experimental approaches, many authors have investigated the effect of the presence within the rock of pronounced anisotropic feature on the mechanical behavior in the elastic regime and on strength properties. Fewer attempts however have been made to capture the anisotropy of rocks in the plastic range. In this paper an elastic/viscoplastic non-associated constitutive equation for an initially transversely isotropic material is presented. The model captures the observed dependency of the elastic moduli on the stress state. The limit of the elastic domain is given by an yield function whose expression is a priori unknown and is determined from data. The basic assumption adopted is that the type of anisotropy of the rock does not change during the deformation process. The anisotropy is thus described by a fourth order tensor invariant with respect to any transformation belonging to the symmetry group of the material. This tensor is assumed to be constant: it does not depend on time nor on deformation; A is involved in the expression of the flow rule, of the yield function, and of the failure criterion in the form of a transformed stress tensor. The components of the anisotropic tensor A are determined from the compressive strengths in conjunction with an anisotropic short- term failure The irreversibility is supposed to be due to transient creep, the irreversible stress work per unit volume being considered as hardening parameter. The adequacy of the model is demonstrated by applying it to a stratified sedimentary rock, Tournemire shale.

  18. Polymer inflation

    NASA Astrophysics Data System (ADS)

    Hassan, Syed Moeez; Husain, Viqar; Seahra, Sanjeev S.

    2015-03-01

    We consider the semiclassical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a Gaussian coherent state. For quadratic potentials, the semiclassical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by an epoch of slow-roll inflation. We compute polymer corrections to the slow-roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckian initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  19. Antimocrobial Polymer

    DOEpatents

    McDonald, William F.; Huang, Zhi-Heng; Wright, Stacy C.

    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.

  20. Antimicrobial Polymer

    DOEpatents

    McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2004-09-28

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric 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 metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example 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).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

  1. Hybrid polymer-lipid films as platforms for directed membrane protein insertion.

    PubMed

    Kowal, Justyna; Wu, Dalin; Mikhalevich, Viktoria; Palivan, Cornelia G; Meier, Wolfgang

    2015-05-05

    Hybrids composed of amphiphilic block copolymers and lipids constitute a new generation of biological membrane-inspired materials. Hybrid membranes resulting from self-assembly of lipids and polymers represent adjustable models for interactions between artificial and natural membranes, which are of key importance, e.g., when developing systems for drug delivery. By combining poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) amphiphilic copolymers (PDMS-b-PMOXA) with various phospholipids, we obtained hybrid films with modulated properties and topology, based on phase separation, and the formation of distinct domains. By understanding the factors driving the phase separation in these hybrid lipid-polymer films, we were able to use them as platforms for directed insertion of membrane proteins. Tuning the composition of the polymer-lipids mixtures favored successful insertion of membrane proteins with desired topological distributions (in polymer or/and lipid regions). Controlled insertion and location of membrane proteins in hybrid films make these hybrids ideal candidates for numerous applications where specific spatial functionality is required.

  2. 78 FR 39721 - Constitution Pipeline Company, LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-02

    ... Energy Regulatory Commission Constitution Pipeline Company, LLC; Notice of Application Take notice that on June 13, 2013, Constitution Pipeline Company, LLC (Constitution), having its principal place of...\\ Constitution further requests that the Commission grant Constitution a blanket certificate authorizing...

  3. Solubility properties in polymers and biological media. 7. An analysis of toxicant properties that influence inhibition of bioluminescence in photobacterium phosphoreum (the Microtox test)

    SciTech Connect

    Kamlet, M.J.; Doherty, R.M.; Veith, G.D.; Taft, R.W.; Abraham, M.H.

    1986-07-01

    Inhibition of bioluminescence in Photobacterium phosphoreum (the Microtox test) has been proposed as a cost-effective prescreening procedure to eliminate the relatively more innocuous chemicals from testing programs for toxicities of organic chemicals to fish. The biological response, as a function of toxicant properties, is given by log EC/sub 50/ (in ..mu..molL) = 7.61 - 4.11 anti V100 - 1.54 ..pi..* + 3.94..beta.. - 1.51..cap alpha../sub m/ n = 38, r = 0.987, SD = 0.28 where anti V is the solute molar volume and ..pi..*, ..beta.., and ..cap alpha../sub m/ are the solvatochromic parameters that measure dipolaritypolarizability, hydrogen-bond acceptor basicity, and hydrogen-bond donor acidity of the solute (toxicant). The above equation applies to compounds that act by a nonreactive toxicity mechanism, and it is suggested that for certain compounds, which are outliers relative to the above equation, reactive toxicity properties mask the effects of the nonreactive mechanism. The above equation is compared with a correlation of log EC/sub 50/ with octanolwater partition coefficients. 25 references, 2 figures, 2 tables.

  4. Polymer micelle assisted transport and delivery of model hydrophilic components inside a biological lipid vesicle: a coarse-grain simulation study.

    PubMed

    Srinivas, Goundla; Mohan, Ram V; Kelkar, Ajit D

    2013-10-10

    Understanding drug transportation and delivery mechanism from a molecular viewpoint is essential to find better treatment pathways. Despite the fact that many significant drugs such as anticancer doxorubicin and mitoxantrone are predominantly hydrophilic, an efficient methodology to deliver hydrophilic drug components is not well established. Here we explore this problem by studying "patchy" polymeric micelle assisted hydrophilic component transportation across a lipid membrane and delivery inside a biological lipid vesicle. Using the MARTINI force field as the basis, we study the interaction of polymeric micelle with DPPC lipid vesicles in detail. In order to facilitate hydrophilic drug transportation study, a primitive CG model for hydrophilic drug component is used. Extensive simulations carried out over hundreds of nanoseconds demonstrate successful encapsulation, transportation of hydrophilic components by patchy polymeric micelles. Results show the polymeric micelle releases a significant portion of hydrophilic contents inside the lipid vesicle. The present simulation study also reveals a possible mechanism for efficient hydrophilic component transportation and delivery. Insights from this study could potentially help the experimental community to design better delivery vehicles, especially for hydrophilic drug molecules.

  5. State Constitutionalism: Completing the Interdisciplinary Study of Constitutional Law and Political Theory.

    ERIC Educational Resources Information Center

    Williams, Robert F.

    1993-01-01

    Argues that a complete and accurate understanding of constitutional history and constitutional law requires the study of state constitutions. Maintains that state constitutions contain a coherent political theory that is, in important respects, at variance with the concept of federalism. (CFR)

  6. Constitutional and Non-Constitutional Governments...Similarities and Differences throughout History. Resource Packet.

    ERIC Educational Resources Information Center

    Pallasch, Brian Thomas

    This civic education resource packet is designed to provide teachers, community leaders, and other civic educators with an understanding of the differences between constitutional and non-constitutional governments. Six papers discussing the topic are included: "The Differences bewteen Constitutional and Non-Constitutional Governments" (John…

  7. 75 FR 57835 - Constitution Day and Citizenship Day, Constitution Week, 2010

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-22

    ... Proclamation 8562--Constitution Day and Citizenship Day, Constitution Week, 2010 Proclamation 8563--National POW/MIA Recognition Day, 2010 #0; #0; #0; Presidential Documents #0; #0; #0;#0;Federal Register / Vol... President ] Proclamation 8562 of September 16, 2010 Constitution Day and Citizenship Day, Constitution...

  8. 78 FR 57777 - Constitution Day and Citizenship Day, Constitution Week, 2013

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... September 19, 2013 Part IV The President Proclamation 9019--Constitution Day and Citizenship Day, Constitution Week, 2013 Proclamation 9020--Honoring the Victims of the Tragedy at the Washington Navy Yard #0... September 16, 2013 Constitution Day and Citizenship Day, Constitution Week, 2013 By the President of...

  9. 77 FR 57981 - Constitution Day and Citizenship Day, Constitution Week, 2012

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-18

    ... September 18, 2012 Part VI The President Proclamation 8862--Constitution Day and Citizenship Day, Constitution Week, 2012 #0; #0; #0; Presidential Documents #0; #0; #0;#0;Federal Register / Vol. 77 , No. 181... ] Proclamation 8862 of September 13, 2012 Constitution Day and Citizenship Day, Constitution Week, 2012 By the...

  10. Mechanistic Constitutive Models for Rubber Elasticity and Viscoelasticity

    SciTech Connect

    Puso, M

    2003-01-21

    Physically based models which describe the finite strain behavior of vulcanized rubber are developed. Constitutive laws for elasticity and viscoelasticity are derived by integrating over orientation space the forces due to each individual polymer chain. A novel scheme is presented which effectively approximates these integrals in terms of strain and strain invariants. In addition, the details involving the implementation of such models into a quasi-static large strain finite element formulation are provided. In order to account for the finite extensibility of a molecular chain, Langevin statistics is used to model the chain response. The classical statistical model of rubber assumes that polymer chains interact only at the chemical crosslinks. It is shown that such model when fitted for uniaxial tension data cannot fit compression or equibiaxial data. A model which incorporates the entanglement interactions of surrounding chains, in addition to the finite extensibility of the chains, is shown to give better predictions than the classical model. The technique used for approximating the orientation space integral was applied to both the classical and entanglement models. A viscoelasticity model based on the force equilibration process as described by Doi and Edwards is developed. An assumed form for the transient force in the chain is postulated. The resulting stress tensor is composed of an elastic and a viscoelastic portion with the elastic stress given by the proposed entanglement model. In order to improve the simulation of experimental data, it was found necessary to include the effect of unattached or dangling polymer chains in the viscoelasticity model. The viscoelastic effect of such chains is the manifestation of a disengagement process. This disengagement model for unattached polymer chains motivated an empirical model which was very successful in simulating the experimental results considered.

  11. Molecularly imprinted polymers for biomedical and biotechnological applications

    NASA Astrophysics Data System (ADS)

    Dmitrienko, E. V.; Pyshnaya, I. A.; Martyanov, O. N.; Pyshnyi, D. V.

    2016-05-01

    This survey covers main advances in the preparation and application of molecularly imprinted polymers which are capable of specific recognition of biologically active compounds. The principles underlying the production of highly efficient and template-specific molecularly imprinted polymers are discussed. The focus is on the imprinting of highly structured macromolecular and supramolecular templates. The existing and potential applications of molecularly imprinted polymers in various fields of chemistry and molecular biology are considered. The bibliography includes 261 references.

  12. Electrochemical Sensors Based on Organic Conjugated Polymers

    PubMed Central

    Rahman, Md. Aminur; Kumar, Pankaj; Park, Deog-Su; Shim, Yoon-Bo

    2008-01-01

    Organic conjugated polymers (conducting polymers) have emerged as potential candidates for electrochemical sensors. Due to their straightforward preparation methods, unique properties, and stability in air, conducting polymers have been applied to energy storage, electrochemical devices, memory devices, chemical sensors, and electrocatalysts. Conducting polymers are also known to be compatible with biological molecules in a neutral aqueous solution. Thus, these are extensively used in the fabrication of accurate, fast, and inexpensive devices, such as biosensors and chemical sensors in the medical diagnostic laboratories. Conducting polymer-based electrochemical sensors and biosensors play an important role in the improvement of public health and environment because rapid detection, high sensitivity, small size, and specificity are achievable for environmental monitoring and clinical diagnostics. In this review, we summarized the recent advances in conducting polymer-based electrochemical sensors, which covers chemical sensors (potentiometric, voltammetric, amperometric) and biosensors (enzyme based biosensors, immunosensors, DNA sensors). PMID:27879698

  13. Polymer solutions

    DOEpatents

    Krawczyk, Gerhard Erich; Miller, Kevin Michael

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  14. Antimicrobial polymers.

    PubMed

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed.

  15. Constitutive receptor systems for drug discovery.

    PubMed

    Chen, G; Jayawickreme, C; Way, J; Armour, S; Queen, K; Watson, C; Ignar, D; Chen, W J; Kenakin, T

    1999-12-01

    This paper discusses the use of constitutively active G-protein-coupled receptor systems for drug discovery. Specifically, the ternary complex model is used to define the two major theoretical advantages of constitutive receptor screening-namely, the ability to detect antagonists as well as agonists directly and the fact that constitutive systems are more sensitive to agonists. In experimental studies, transient transfection of Chinese hamster ovary cyclic AMP response element (CRE) luciferase reporter cells with cDNA for human parathyroid hormone receptor, glucagon receptor, and glucagon-like peptide (GLP-1) receptor showed cDNA concentration-dependent constitutive activity with parathyroid hormone (PTH-1) and glucagon. In contrast, no constitutive activity was observed for GLP-1 receptor, yet responses to GLP-1 indicated that receptor expression had taken place. In another functional system, Xenopus laevi melanophores transfected with cDNA for human calcitonin receptor showed constitutive activity. Nine ligands for the calcitonin receptor either increased or decreased constitutive activity in this assay. The sensitivity of the system to human calcitonin increased with increasing constitutive activity. These data indicate that, for those receptors which naturally produce constitutive activity, screening in this mode could be advantageous over other methods.

  16. Testing of constitutive models in LAME.

    SciTech Connect

    Hammerand, Daniel Carl; Scherzinger, William Mark

    2007-09-01

    Constitutive models for computational solid mechanics codes are in LAME--the Library of Advanced Materials for Engineering. These models describe complex material behavior and are used in our finite deformation solid mechanics codes. To ensure the correct implementation of these models, regression tests have been created for constitutive models in LAME. A selection of these tests is documented here. Constitutive models are an important part of any solid mechanics code. If an analysis code is meant to provide accurate results, the constitutive models that describe the material behavior need to be implemented correctly. Ensuring the correct implementation of constitutive models is the goal of a testing procedure that is used with the Library of Advanced Materials for Engineering (LAME) (see [1] and [2]). A test suite for constitutive models can serve three purposes. First, the test problems provide the constitutive model developer a means to test the model implementation. This is an activity that is always done by any responsible constitutive model developer. Retaining the test problem in a repository where the problem can be run periodically is an excellent means of ensuring that the model continues to behave correctly. A second purpose of a test suite for constitutive models is that it gives application code developers confidence that the constitutive models work correctly. This is extremely important since any analyst that uses an application code for an engineering analysis will associate a constitutive model in LAME with the application code, not LAME. Therefore, ensuring the correct implementation of constitutive models is essential for application code teams. A third purpose of a constitutive model test suite is that it provides analysts with example problems that they can look at to understand the behavior of a specific model. Since the choice of a constitutive model, and the properties that are used in that model, have an enormous effect on the results of an

  17. Depletion-induced forces and crowding in polymer-nanoparticle mixtures: Role of polymer shape fluctuations and penetrability

    NASA Astrophysics Data System (ADS)

    Lim, Wei Kang; Denton, Alan R.

    2016-01-01

    Depletion forces and macromolecular crowding govern the structure and function of biopolymers in biological cells and the properties of polymer nanocomposite materials. To isolate and analyze the influence of polymer shape fluctuations and penetrability on depletion-induced interactions and crowding by nanoparticles, we model polymers as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor of an ideal random walk. Within this model, we apply Monte Carlo simulation methods to compute the depletion-induced potential of mean force between hard nanospheres and crowding-induced shape distributions of polymers in the protein limit, in which polymer coils can be easily penetrated by smaller nanospheres. By comparing depletion potentials from simulations of ellipsoidal and spherical polymer models with predictions of polymer field theory and free-volume theory, we show that polymer depletion-induced interactions and crowding depend sensitively on polymer shapes and penetrability, with important implications for bulk thermodynamic phase behavior.

  18. Depletion-induced forces and crowding in polymer-nanoparticle mixtures: Role of polymer shape fluctuations and penetrability.

    PubMed

    Lim, Wei Kang; Denton, Alan R

    2016-01-14

    Depletion forces and macromolecular crowding govern the structure and function of biopolymers in biological cells and the properties of polymer nanocomposite materials. To isolate and analyze the influence of polymer shape fluctuations and penetrability on depletion-induced interactions and crowding by nanoparticles, we model polymers as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor of an ideal random walk. Within this model, we apply Monte Carlo simulation methods to compute the depletion-induced potential of mean force between hard nanospheres and crowding-induced shape distributions of polymers in the protein limit, in which polymer coils can be easily penetrated by smaller nanospheres. By comparing depletion potentials from simulations of ellipsoidal and spherical polymer models with predictions of polymer field theory and free-volume theory, we show that polymer depletion-induced interactions and crowding depend sensitively on polymer shapes and penetrability, with important implications for bulk thermodynamic phase behavior.

  19. BioArtificial polymers

    NASA Astrophysics Data System (ADS)

    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.

  20. ESIPT and FRET probes for monitoring nanoparticle polymer coating stability.

    PubMed

    Azcárate, Julio C; Díaz, Sebastián A; Fauerbach, Jonathan A; Gillanders, Florencia; Rubert, Aldo A; Jares-Erijman, Elizabeth A; Jovin, Thomas M; Fonticelli, Mariano H

    2017-06-29

    Coating strategies of inorganic nanoparticles (NPs) can provide properties unavailable to the NP core alone, such as targeting, specific sensing, and increased biocompatibility. Non-covalent amphiphilic NP capping polymers function via hydrophobic interactions with surface ligands and are extensively used to transfer NPs to aqueous media. For applications of coated NPs as actuators (sensors, markers, or for drug delivery) in a complex environment, such as biological systems, it is important to achieve a deep understanding of the factors affecting coating stability and behavior. We have designed a system that tests the coating stability of amphiphilic polymers through a simple fluorescent readout using either polarity sensing ESIPT (excited state intramolecular proton transfer) dyes or NP FRET (Förster resonance energy transfer). The stability of the coating was determined in response to changes in polarity, pH and ionic strength in the medium. Using the ESIPT system we observed linear changes in signal up to ∼20-25% v/v of co-solvent addition, constituting a break point. Based on such data, we propose a model for coating instability and the important adjustable parameters, such as the electrical charge distribution. FRET data provided confirmatory evidence for the model. The ESIPT dyes and FRET based methods represent new, simple tools for testing NP coating stability in complex environments.

  1. From Confederation to Constitution: 1781-1789.

    ERIC Educational Resources Information Center

    Urofsky, Melvin I.; Cox, Nancy

    Students should achieve a higher level of understanding and appreciation of the evolving nature of the U.S. Constitution and its relevance to contemporary societal issues by studying historical documents from the period of time between the Articles of Confederation and the Constitution. This document begins with a history of that period and of the…

  2. The Constitution at 200: Celebration Amidst Controversy.

    ERIC Educational Resources Information Center

    Collins, Sheila D.

    1987-01-01

    Current debates about the Constitution fall into the three following categories: (1) reappraisals of consitutional origins; (2) disagreements on hermeneutical principles used in contemporary applications; and (3) discussions of contemporary events whose consequences for law and political stability could not have been foreseen by the Constitution's…

  3. From Confederation to Constitution: 1781-1789.

    ERIC Educational Resources Information Center

    Urofsky, Melvin I.; Cox, Nancy

    Students should achieve a higher level of understanding and appreciation of the evolving nature of the U.S. Constitution and its relevance to contemporary societal issues by studying historical documents from the period of time between the Articles of Confederation and the Constitution. This document begins with a history of that period and of the…

  4. The Constitution at 200: Celebration Amidst Controversy.

    ERIC Educational Resources Information Center

    Collins, Sheila D.

    1987-01-01

    Current debates about the Constitution fall into the three following categories: (1) reappraisals of consitutional origins; (2) disagreements on hermeneutical principles used in contemporary applications; and (3) discussions of contemporary events whose consequences for law and political stability could not have been foreseen by the Constitution's…

  5. Women and the Constitution. Curriculum Unit.

    ERIC Educational Resources Information Center

    MacGregor, Molly Murphy

    The purpose of this curriculum unit is to give students a better understanding of the history of the relationship between women and constitutional issues. The study of women and the United States Constitution is an important reminder of the complexity of a democracy. In the United States, even today, the ideology of freedom and justice is often…

  6. 29 CFR 452.18 - Constitutional officers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... performs no executive functions and whose duties are confined to promoting the interests of members in... officer position by the union's constitution, or the holder of the position performs executive functions... constitution, are not members of any executive board or similar governing body, and do not perform...

  7. 29 CFR 452.18 - Constitutional officers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... performs no executive functions and whose duties are confined to promoting the interests of members in... officer position by the union's constitution, or the holder of the position performs executive functions... constitution, are not members of any executive board or similar governing body, and do not perform...

  8. The United States and the Indian Constitution.

    ERIC Educational Resources Information Center

    Weil, Jonathan S.

    India, a huge land with the second largest population in the world, socially and economically poor, and culturally and linguistically diverse, became the largest democracy in the world on November 26, 1949 with the adoption of the Indian Constitution. The goals of that constitution are: (1) the achievement of national unity and stability; (2) the…

  9. The Educational Significance of Canada's Constitution.

    ERIC Educational Resources Information Center

    Wells, Allen R.

    1985-01-01

    Traces the historical relationship of Canada's educational system to its constitution. Concludes that the significance of the patriation of Canada's constitution for education includes strengthening a drive for bilingual education, promoting equality of opportunity, and continuing education as a provincial concern while unifying, nationally, the…

  10. Resources for Teaching about the Constitution.

    ERIC Educational Resources Information Center

    Cohen, Cheryl B.

    1987-01-01

    Describes eight resources for teaching about the United States Constitution available from ERIC. Described are instructional materials for junior and senior high school students on such topics as (1) the role of the U.S. Supreme Court, (2) freedom of the press, (3) the history of the United States Constitution, and (4) problems of the…

  11. Politics, Economics, and Religion in the Constitution.

    ERIC Educational Resources Information Center

    Stevens, Richard G.

    1986-01-01

    Explains the relationship between politics, economics, and religion through the philosophies of Smith, Hobbes, and Locke. Maintains that the unamended Constitution is a reconciliation of politics, religion, and economics. Defends this claim by examining property rights and the Constitution's regard to means in pursuance of freedom and justice.…

  12. The Five Great Ideas of Our Constitution.

    ERIC Educational Resources Information Center

    Starr, Isidore

    1987-01-01

    Identifies five great ideas of the U.S. Constitution as power, liberty, justice, equality, and property. The first of two installments, article focuses on how ideas of power and liberty are presented in the Constitution. It also discusses how people may exercise power through voting and public protest and liberty through their First Amendment…

  13. The Meaning of Religion: A Constitutional Perspective.

    ERIC Educational Resources Information Center

    Lilly, Edward R.

    The problems of formulating a legal definition of religion as used in the U.S. Constitution may be traced through the Supreme Court's interpretation of the word. According to the U.S. Constitution, religious tests cannot be required for any office or public trust under the central government. The Bill of Rights states that the national government…

  14. Public and Constitutional Support for Character Education.

    ERIC Educational Resources Information Center

    Vessels, Gordon G.; Boyd, Stephen M.

    1996-01-01

    Character education thrives on an informed understanding of constitutional principles and an inclusive commitment-building process. U.S. Supreme Court opinions that clarify public school students' free speech rights have established values education as a constitutionally acceptable practice. Challenges might lie in possible violations of the First…

  15. World Studies through a Comparative Constitutional Prism.

    ERIC Educational Resources Information Center

    Robinson, Donald

    1992-01-01

    Emphasizes the importance of understanding the development of democracy around the world by comparative study of constitutions. Uses the development of the Japanese constitution after World War II as a case study. Describes the work of the team appointed by General Douglas MacArthur and the significance of the clause guaranteeing equal rights for…

  16. The Constitution in the Twentieth Century.

    ERIC Educational Resources Information Center

    Murphy, Paul L.

    1987-01-01

    Investigates the development of the United States Constitution in the twentieth century up to and including the Burger Court. Contends that interpreting the Constitution is an important issue of our times. Consequently argues that we should teach students about the development of this document. (RKM)

  17. Advanced Polymer

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In the mid-1980's, Langley developed a polyimide sulfone, combining desirable properties of two classes of polymers. Composites and other products made from polyimide sulfone can be used with solvents and corrosive fluids, are light weight, low cost and can be easily fabricated for a wide range of industrial uses. High Technology Systems, Inc. obtained a license for the polymer and was awarded a Small Business Innovation Research (SBIR) contract for development in a powder form. Although its principal use is as a matrix resin for composites, the material can also be used as a high temperature structural adhesive for aircraft structures and as a coating for protection from heat and radiation for electronic components.

  18. Constitutive modeling of inelastic anisotropic material response

    NASA Technical Reports Server (NTRS)

    Stouffer, D. C.

    1984-01-01

    A constitutive equation was developed to predict the inelastic thermomechanical response of single crystal turbine blades. These equations are essential for developing accurate finite element models of hot section components and contribute significantly to the understanding and prediction of crack initiation and propagation. The method used was limited to unified state variable constitutive equations. Two approaches to developing an anisotropic constitutive equation were reviewed. One approach was to apply the Stouffer-Bodner representation for deformation induced anisotropy to materials with an initial anisotropy such as single crystals. The second approach was to determine the global inelastic strain rate from the contribution of the slip in each of the possible crystallographic slip systems. A three dimensional finite element is being developed with a variable constitutive equation link that can be used for constitutive equation development and to predict the response of an experiment using the actual specimen geometry and loading conditions.

  19. Phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    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.

  20. Theoretical Polymers.

    DTIC Science & Technology

    1976-10-07

    for the correlation length of 3/4, while 0.72 is observed. Then followed several talks on the expansion coefficient a, the virial coefficients and...calculation of the virial coefficient and c~2. These quantities can be considered merely a testing ground for the use of this method to polymer...the second viria]. coefficient , A2, to be zero and the intrinsic viscosity dependent on~VW for polystyrene mole-cular weights between 33,000 and one

  1. Polymer blends

    DOEpatents

    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.

  2. Fabrication of ciprofloxacin molecular imprinted polymer coating on a stainless steel wire as a selective solid-phase microextraction fiber for sensitive determination of fluoroquinolones in biological fluids and tablet formulation using HPLC-UV detection.

    PubMed

    Mirzajani, Roya; Kardani, Fatemeh

    2016-04-15

    A molecularly imprinted polymer (MIP) fiber on stainless steel wire using ciprofloxacin template with a mild template removal condition was synthetized and evaluated for fiber solid phase microextraction (SPME) of fluoroquinolones (FQs) from biological fluids and pharmaceutical samples, followed by high performance liquid chromatography analysis with UV detection (HPLC-UV). The developed MIP fiber exhibited high selectivity for the analytes in complex matrices. The coating of the fibers were inspected using fourier transform infrared spectrophotometry, thermogaravimetric analysis, energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The fiber shows high thermal stability (up to 300°C), good reproducibility and long lifetime. The composite coating did not swell in organic solvents nor did it strip off from the substrate. It was also highly stable and extremely adherent to the surface of the stainless steel fiber. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some FQs. The effective parameters influencing the microextraction efficiency such as pH, extraction time, desorption condition, and stirring rate were investigated. Under optimized conditions, the limits of detection of the four FQs ranged from 0.023-0.033 μg L(-1) (S/N=5) and the calibration graphs were linear in the concentration range from 0.1-40 μg L(-1), the inter-day and intraday relative standard deviations (RSD) for various FQs at three different concentration level (n=5) using a single fiber were 1.1-4.4% and the fiber to fiber RSD% (n=5) was 4.3-6.7% at 5 μg L(-1) of each anlyetes. The method was successfully applied for quantification of FQs in real samples including serum, plasma and tablet formulation with the recoveries between 97 to 102%.

  3. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  4. Constitutive model for fiber-reinforced materials with deformable matrices.

    PubMed

    Planas, J; Guinea, G V; Elices, M

    2007-10-01

    A great number of biological structures are composed of fibers (elastin, collagen, etc.) dispersed on an aqueous matrix in such a complex way that a detailed mechanical analysis based on microconstituents is, for practical purposes, out of reach. Consequently, the preferred approach to the mechanical behavior of these materials is based on setting up of constitutive equations that homogenize the behavior while capturing their main microstructural features. This work presents a simple macroscopic model for fiber-reinforced materials with deformable matrices, especially suited to many biological structural tissues. The constitutive equation is derived by imposing equivalence between the virtual works of both the fiber-reinforced and the equivalent continuum media, showing that it is independent of the control volume used for such equivalence. The model is particularized to incompressible materials, and an extension to orthotropic biological fibers is shown. Numerical simulations of uniaxial tests on silk fibers demonstrate the model's ability to capture the progressive alignment of the microconstituents under large deformations.

  5. 3 CFR 8862 - Proclamation 8862 of September 13, 2012. Constitution Day and Citizenship Day, Constitution Week...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Constitution has guided our progress from 13 to 50 United States that stretch from sea to shining sea. It has... reach. As we mark this 225th anniversary of the signing of our Constitution, we also recognize the...

  6. Synthetic Biology - The Synthesis of Biology.

    PubMed

    Ausländer, Simon; Ausländer, David; Fussenegger, Martin

    2016-12-11

    Synthetic biology envisages the engineering of man-made living biomachines from standardized components that can perform pre-defined 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 signalling 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 and the application of efficient genome-wide intervention techniques point to the future of synthetic biology: the creation of living designer cells with tailored desirable properties for biomedicine and biotechnology.

  7. PREFACE: Polymers and Complex Matter

    NASA Astrophysics Data System (ADS)

    von Ferber, Christian

    2005-05-01

    This special issue, in honour of Lothar Schäfer on the occasion of his 60th birthday, focuses on polymers and complex matter and covers a broad range of topics both in terms of subject matter and methods applied. This reflects the wide and open minded interests of the honoree. Lothar Schäfer began his career in Heidelberg working on theoretical nuclear physics with H A Weidenmüller. Following a stay at the CEN Saclay in 1974, he turned to the field of critical phenomena. He made fundamental contributions to the subject of disordered systems, in particular on Goldstone modes with F J Wegner and on Anderson localization with A U Pruisken. With T A Witten he formulated a truly field theoretic description of general polymer solutions. Polymers in solution and the renormalization group approach to their experimentally accessible properties have, since 1980 in Hannover and 1983 in Essen, been his primary field of research summarized in his book Excluded Volume Effects in Polymer Solutions as Explained by the Renormalization Group covering `all you ought to know' on the subject. This work is complemented by analytical studies of polymer dynamics. The subjects contained in this special issue encompass soft matter and its rheology, polymers in confinement and their role in short- and long-range colloidal interactions: discussing lenses, dumbbells, rods and dendrimers. Special topics are short chains, directed molecules and gas permeation through polymers. Applications of polymer theory to biological systems include the interactions between DNA molecules and between DNA and proteins and the polymerization of the actin skeleton. Work on random matrix theory, functional renormalization and ageing is devoted to the implications of disorder. Finally, more general aspects of the field theory of polymers and complex matter are discussed, like the Hubbard-Stratonovich transformation, renormalization of polymer field theory, exact renormalization group equations, percolation and

  8. Constitutive Modeling and Numerical Simulation of Frp Confined Concrete Specimens

    NASA Astrophysics Data System (ADS)

    Smitha, Gopinath; Ramachandramurthy, Avadhanam; Nagesh, Ranganatha Iyer; Shahulhameed, Eduvammal Kunhimoideen

    2014-09-01

    Fiber-reinforced polymer (FRP) composites are generally used for the seismic retrofit of concrete members to enhance their strength and ductility. In the present work, the confining effect of Carbon Fiber-Reinforced Polymer (CFRP) composite layers has been investigated by numerical simulation. The numerical simulation has been carried out using nonlinear finite element analysis (FEA) to predict the response behaviour of CFRP-wrapped concrete cylinders. The nonlinear behaviour of concrete in compression and the linear elastic behaviour of CFRP has been modeled using an appropriate constitutive relationship. A cohesive model has been developed for modeling the interface between the concrete and CFRP. The interaction and damage failure criteria between the concrete to the cohesive element and the cohesive element to the CFRP has also been accounted for in the modeling. The response behaviour of the wrapped concrete specimen has been compared with the proposed interface model and with a perfectly bonded condition. The results obtained from the present study showed good agreement with the experimental load-displacement response and the failure pattern in the literature. Further, a sensitivity analysis has been carried out to study the effect of the number of layers of CFRP on the concrete specimens. It has been observed that wrapping with two layers was found to be the optimum, beyond which the response becomes flexible but with a higher load-carrying capacity

  9. Electrospinning of Bioinspired Polymer Scaffolds.

    PubMed

    Araujo, Jose V; Carvalho, Pedro P; Best, Serena M

    2015-01-01

    Electrospinning is a technique used in the production of polymer nanofibre meshes. The use of biodegradable and biocompatible polymers to produce nanofibres that closely mimic the extracellular matrix (ECM) of different tissues has opened a wide range of possibilities for the application of electrospinning in Tissue Engineering. It is believed that nano-features (such as voids and surface cues) present in nanofibre mesh scaffolds, combined with the chemical composition of the fibres, can stimulate cell attachment, growth and differentiation. Despite the widespread use of electrospun nanofibres in tissue engineering, the present chapter will focus on the advances made in the utilisation of these materials in bone, cartilage and tooth related applications. Several aspects will be taken into consideration, namely the choice of polymers, the surface modification of the nanofibres in order to achieve mineralisation, and also the biological application of such materials.

  10. Closing in on the constitution of consciousness

    PubMed Central

    Miller, Steven M.

    2014-01-01

    The science of consciousness is a nascent and thriving field of research that is founded on identifying the minimally sufficient neural correlates of consciousness. However, I have argued that it is the neural constitution of consciousness that science seeks to understand and that there are no evident strategies for distinguishing the correlates and constitution of (phenomenal) consciousness. Here I review this correlation/constitution distinction problem and challenge the existing foundations of consciousness science. I present the main analyses from a longer paper in press on this issue, focusing on recording, inhibition, stimulation, and combined inhibition/stimulation strategies, including proposal of the Jenga analogy to illustrate why identifying the minimally sufficient neural correlates of consciousness should not be considered the ultimate target of consciousness science. Thereafter I suggest that while combined inhibition and stimulation strategies might identify some constitutive neural activities—indeed minimally sufficient constitutive neural activities—such strategies fail to identify the whole neural constitution of consciousness and thus the correlation/constitution distinction problem is not fully solved. Various clarifications, potential objections and related scientific and philosophical issues are also discussed and I conclude by proposing new foundational claims for consciousness science. PMID:25452738

  11. 3 CFR 8562 - Proclamation 8562 of September 16, 2010. Constitution Day and Citizenship Day, Constitution Week...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., Constitution Week, 2010By the President of the United States of America A Proclamation The summer of 1787 was a... Convention in Philadelphia established a Constitution for the United States of America, signing the finished... taking a solemn oath to “support and defend the Constitution and laws of the United States of...

  12. 3 CFR 8714 - Proclamation 8714 of September 16, 2011. Constitution Day and Citizenship Day, Constitution Week...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., Constitution Week, 2011By the President of the United States of America A Proclamation In the summer of 1787... months of fierce debate and hard-fought compromise, the delegates signed the Constitution of the United States. For more than two centuries, the Constitution has presided as the supreme law of the...

  13. 3 CFR 9019 - Proclamation 9019 of September 16, 2013. Constitution Day and Citizenship Day, Constitution Week...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., Constitution Week, 2013By the President of the United States of America A Proclamation In May of 1787... each year as “Constitution Week.” NOW, THEREFORE, I, BARACK OBAMA, President of the United States of... through September 23, 2013, as Constitution Week. I encourage Federal, State, and local officials, as...

  14. Electrocaloric effect in ferroelectric polymers

    NASA Astrophysics Data System (ADS)

    Lu, S. G.; Rozic, B.; Zhang, Q. M.; Kutnjak, Z.; Pirc, R.

    2012-06-01

    The electrocaloric effect (ECE) of poly (vinyledene fluoride-trifluoroethylene) (P(VDF-TrFE)) 55/45 mol% copolymers was directly measured, which confirms the results deduced from Maxwell relation. The adiabatic temperature change Δ T under a given electric field peaks at the ferroelectric-paraelectric (FE-PE) transition. Away from it, ECE becomes small. Δ T versus applied electric field can be described well by a modified Belov-Goryaga equation. The ECE in ferroelectric polymers, especially near FE-PE transition where larger ECE is observed, are analyzed under different boundary conditions employing phenomenological theory and constitutive equations. The secondary pyroelectricity is found to play a significant role which enhances ECE in ferroelectric polymers.

  15. [The right to health. Constitutional dimensions].

    PubMed

    Pestalozza, C

    2007-09-01

    A fundamental "right to health" is expressly guaranteed by the constitutions of several Bundesländer, but unknown to the German Federal Constitution. Instead the Federal Constitutional Court has - especially on the basis of related human rights - developed the obligation of the State to protect everybody's life and physical integrity, which in some respects comes near to a "right to health". The State's autonomy in financial matters, the scarcity of its financial resources and the individual's natural responsibility for his own health though advise against exaggerated hopes set in a "right to health".

  16. Small-molecule modulators of the constitutive androstane receptor

    PubMed Central

    Cherian, Milu T.; Chai, Sergio C.; Chen, Taosheng

    2015-01-01

    Introduction The constitutive androstane receptor (CAR) induces drug-metabolizing enzymes for xenobiotic metabolism. Areas covered This review covers recent advances in elucidating the biological functions of CAR and its modulation by a growing number of agonists and inhibitors. Expert opinion Extrapolation of animal CAR function to that of humans should be carefully scrutinized, particularly when rodents are used in evaluating the metabolic profile and carcinogenic properties of clinical drugs and environmental chemicals. Continuous efforts are needed to discover novel CAR inhibitors, with extensive understanding of their inhibitory mechanism, species selectivity, and discriminating power against other xenobiotic sensors. PMID:25979168

  17. What Would Constitute Evidence for Life on Icy Moons?

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Hoehler, T. M.

    2017-01-01

    For the first time since Viking, NASA is considering missions that would include life detection as a primary objective, making it critical to develop and evaluate a diverse set of strategies for seeking evidence of life. The central question is: what should be the target of our search that, if found, would constitute a near-certain evidence for life? Since life on icy moons might be quite different from terrestrial life, we should concentrate on features of biological systems that are considered universal and are unlikely to emerge through abiotic means.

  18. Functionalized synthetic biodegradable polymer scaffolds for tissue engineering.

    PubMed

    Liu, Xiaohua; Holzwarth, Jeremy M; Ma, Peter X

    2012-07-01

    Scaffolds (artificial ECMs) play a pivotal role in the process of regenerating tissues in 3D. Biodegradable synthetic polymers are the most widely used scaffolding materials. However, synthetic polymers usually lack the biological cues found in the natural extracellular matrix. Significant efforts have been made to synthesize biodegradable polymers with functional groups that are used to couple bioactive agents. Presenting bioactive agents on scaffolding surfaces is the most efficient way to elicit desired cell/material interactions. This paper reviews recent advancements in the development of functionalized biodegradable polymer scaffolds for tissue engineering, emphasizing the syntheses of functional biodegradable polymers, and surface modification of polymeric scaffolds.

  19. Polymers influencing transportability profile of drug

    PubMed Central

    Gaikwad, Vinod L.; Bhatia, Manish S.

    2013-01-01

    Drug release from various polymers is generally governed by the type of polymer/s incorporated in the formulation and mechanism of drug release from polymer/s. A single polymer may show one or more mechanisms of drug release out of which one mechanism is majorly followed for drug release. Some of the common mechanisms of drug release from polymers were, diffusion, swelling, matrix release, leaching of drug, etc. Mechanism or rate of drug release from a polymer or a combination of polymers can be predicted by using different computational methods or models. These models were capable of predicting drug release from its dosage form in advance without actual formulation and testing of drug release from dosage form. Quantitative structure–property relationship (QSPR) is an important tool used in the prediction of various physicochemical properties of actives as well as inactives. Since last several decades QSPR has been applied in new drug development for reducing the total number of drugs to be synthesized, as it involves a selection of the most desirable compound of interest. This technique was also applied in predicting in vivo performance of drug/s for various parameters. QSPR serves as a predictive tool to correlate structural descriptors of molecules with biological as well as physicochemical properties. Several researchers have contributed at different extents in this area to modify various properties of pharmaceuticals. The present review is focused on a study of different polymers that influence the transportability profiles of drugs along with the application of QSPR either to study different properties of polymers that regulate drug release or in predicting drug transportability from different polymer systems used in formulations. PMID:24227951

  20. Recent progress and prospects in Sasang constitutional medicine: a traditional type of physiome-based treatment.

    PubMed

    Kim, Jong Yeol; Noble, Denis

    2014-09-01

    The history of the constitution perspective in medical care dates back thousands of years and extends from the East to the West. Among the various forms of constitutional medicine, Sasang constitutional medicine (SCM) is a holistic, tailored medical approach that is based on a well-structured theoretical system that includes physiopathological disciplines. Scientific evidence has demonstrated that SCM typology has a constitution-specific basis in anthropometrics, physiological characteristics, disease vulnerability, and genetic origins. Furthermore, the recent rise of systems biology, which requires whole body modeling, uses a state-of-the-art approach in interpreting the holistic spirit of Oriental medicine. This article aims to provide an overview of the recent achievements in SCM research and to discuss how the concept of balance in SCM may contribute to the development of large scale modeling in systems biology.

  1. Biologically Inspired Polymer Micro-Patterned Adhesives

    DTIC Science & Technology

    2008-11-01

    SEM image showing smooth adhesion pad at end of tibia in aphid Megoura viciae 12 2. Droplets left on glass slide from tarsal footprint of beetle...or they can be just a smooth pad as in cockroaches, aphids , and ants (see Figure 1b).3 •*,««, -«" Figure 1a. Scanning electron microscope (SEM...image showing smooth adhesion pad (p) at end of tibia in aphid Megoura viciae. [ta = tarsus, ti = tibia. Scale bar = 20 microns (adapted from Lees

  2. Damage induced constitutive response of a thermoplastic related to composites and adhesive bonding

    NASA Technical Reports Server (NTRS)

    Parvin, M.; Knauss, W. G.

    1990-01-01

    The volume-averaged constitutive behavior of a polymer sustaining void growth under dilational deformation is addressed. Polyvinylacetate is deformed between two aluminum beams in a double cantilever geometry and the deformations, recorded with the aid of optical interferometry, are used to deduce the stress-strain behavior of the material as it passes from small strain behavior, through the voiding process, to near-failure under exclusion of rate-sensitivity considerations.

  3. Conjugated Polymers Atypically Prepared in Water

    PubMed Central

    Invernale, Michael A.; Pendergraph, Samuel A.; Yavuz, Mustafa S.; Ombaba, Matthew; Sotzing, Gregory A.

    2010-01-01

    Processability remains a fundamental issue for the implementation of conducting polymer technology. A simple synthetic route towards processable precursors to conducting polymers (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties. PMID:20959869

  4. Cell Partition in Two Polymer Aqueous Phases

    NASA Technical Reports Server (NTRS)

    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.

  5. Cell Partition in Two Polymer Aqueous Phases

    NASA Technical Reports Server (NTRS)

    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.

  6. Chiral Polymers.

    DTIC Science & Technology

    1984-10-01

    TITLE (mid Subttlo) 񓂬-JS. TYPE OF REPORT & PERIOD COVERED CHIRAL POLYMERS /~O~~ R E~NNE 7. AUTHOR(e) 11. CONTRACT OR GRANT NUNSIER(e) J. K. Stille...acrylamide monomer containing a chiral 1,3-dioxane unit as well as both racemic and ( R )-6.-methyl ene-vi-methyl -7-butyrol actone were synthesi zed...or ( R )-propylene oxide (10)6. The key step in this synthesis is the palladium catalyzed carbonylation of 4-bromopent-4-en-2-ol. Thus, either racemic or

  7. Constitutively Active Rhodopsin and Retinal Disease

    PubMed Central

    Park, Paul Shin-Hyun

    2014-01-01

    Rhodopsin is the light receptor in rod photoreceptor cells of the retina that initiates scotopic vision. In the dark, rhodopsin is bound to the chromophore 11-cis retinal, which locks the receptor in an inactive state. The maintenance of an inactive rhodopsin in the dark is critical for rod photoreceptor cells to remain highly sensitive. Perturbations by mutation or absence of 11-cis retinal can cause rhodopsin to become constitutively active, which leads to the desensitization of photoreceptor cells and, in some instances, retinal degeneration. Constitutive activity can arise in rhodopsin by various mechanisms and can cause a variety of inherited retinal diseases including Leber congenital amaurosis, congenital night blindness, and retinitis pigmentosa. In this review, the molecular and structural properties of different constitutively active forms of rhodopsin are overviewed and the possibility that constitutive activity can arise from different active-state conformations is discussed. PMID:24931191

  8. The Constitution and the Black Experiences

    ERIC Educational Resources Information Center

    Miles, E. W.

    1973-01-01

    A review of the constitutional promises to black people, early congressional efforts to fulfill these promises, early court cases construing the Fourteenth Amendment and the impact of these decisions along with their subsequent overruling. (Author/JB)

  9. Capturing the Essence of the Constitution.

    ERIC Educational Resources Information Center

    McMorrow, Catherine

    1987-01-01

    Offers three sample lesson plans for elementary grades designed to demonstrate the religious values inherent in the United States Constitution. Each lesson plan focuses on one amendment and includes a discussion of class activities. (DMM)

  10. Symbolic derivation of potential based constitutive equations

    NASA Astrophysics Data System (ADS)

    Arnold, S. M.; Tan, H. Q.

    1990-05-01

    Structural alloys used in high temperature applications exhibit complex thermomechanical behavior that is inherently time dependent and hereditary, as the current behavior depends not only on current conditions but on the thermomechanical history. Derivation of mathematical expressions (constitutive equations) which describe this high temperature material behavior can be quite time consuming, involved, and error-prone, thus intelligent application of symbolic systems to facilitate this tedious processes can be of significant benefit. Here a computerized package, running under MACSYMA, capable of efficiently deriving potential based constitutive models, in analytical form (involving tensors, partial differentiation, invariants, and the like) is presented. Special purpose utility algorithms are designed and implemented to perform partial differentiation (chain rule), tensor manipulation, case distinction and simplification. Four constitutive theories reported in the literature are utilized to verify implementation accuracy. It is expected that this symbolic package can and will provide a significant incentive to the development of new constitutive theories.

  11. 7 CFR 718.201 - Farm constitution.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...; (ii) Counties do not touch because of a correction line adjustment; or (iii) The land is within 20... increase amount of program benefits received; (2) The farm was not properly constituted the previous time...

  12. 7 CFR 718.201 - Farm constitution.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...; (ii) Counties do not touch because of a correction line adjustment; or (iii) The land is within 20... increase amount of program benefits received; (2) The farm was not properly constituted the previous time...

  13. 7 CFR 718.201 - Farm constitution.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...; (ii) Counties do not touch because of a correction line adjustment; or (iii) The land is within 20... increase amount of program benefits received; (2) The farm was not properly constituted the previous time...

  14. Dynamic constitutional frameworks for DNA biomimetic recognition.

    PubMed

    Catana, Romina; Barboiu, Mihail; Moleavin, Ioana; Clima, Lilia; Rotaru, Alexandru; Ursu, Elena-Laura; Pinteala, Mariana

    2015-02-07

    Linear and cross-linked dynamic constitutional frameworks generated from reversibly interacting linear PEG/core constituents and cationic sites shed light on the dominant coiling versus linear DNA binding behaviours, closer to the histone DNA binding wrapping mechanism.

  15. Smart Polymers with Special Wettability.

    PubMed

    Chang, Baisong; Zhang, Bei; Sun, Taolei

    2017-01-01

    Surface wettability plays a key role in addressing issues ranging from basic life activities to our daily life, and thus being able to control it is an attractive goal. Learning from nature, both of its structure and function, brings us much inspiration in designing smart polymers to tackle this major challenge. Life functions particularly depend on biomolecular recognition-induced interfacial properties from the aqueous phase onto either "soft" cell and tissue or "hard" inorganic bone and tooth surfaces. The driving force is noncovalent weak interactions rather than strong covalent combinations. An overview is provided of the weak interactions that perform vital actions in mediating biological processes, which serve as a basis for elaborating multi-component polymers with special wettabilities. The role of smart polymers from molecular recognitions to macroscopic properties are highlighted. The rationale is that highly selective weak interactions are capable of creating a dynamic synergetic communication in the building components of polymers. Biomolecules could selectively induce conformational transitions of polymer chains, and then drive a switching of physicochemical properties, e.g., roughness, stiffness and compositions, which are an integrated embodiment of macroscopic surface wettabilities.

  16. A Numerical Homogenization Scheme for Glass Particle-Toughened Polymers Under Dynamic Loading

    NASA Astrophysics Data System (ADS)

    Karamnejad, Amin; Ahmed, Awais; Sluys, Lambertus Johannes

    A numerical homogenization scheme is presented to model glass particle-toughened polymer materials under dynamic loading. A constitutive law is developed for the polymer material and validated by comparing the results to experimental test data. A similar constitutive law as that of the polymer material with unknown material parameters is assumed for the glass particle-toughened polymer. A homogenization scheme is used to determine the unknown material parameters from the boundary value problem (BVP) of a representative volume element. Unlike the standard computational homogenization scheme, the proposed numerical homogenization scheme can be used after localization occurs in the material. The proposed multiscale model is then verified against direct numerical simulation.

  17. Constitutive Parameter Measurement Using Double Ridge Waveguide

    DTIC Science & Technology

    2013-03-01

    CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Nathan J. Lehman, Captain, USAF AFIT-ENG-13-M-30 DEPARTMENT OF THE AIR FORCE...copyright protection in the United States. AFIT-ENG-13-M-30 CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Presented to the Faculty...PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE Nathan J. Lehman, B.S.E.E. Captain, USAF Approved: Michael Havrilla, PhD (Chairman) Maj Milo Hyde, PhD

  18. Molecular Mechanisms of Failure in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Gersappe, Dilip

    2002-07-01

    Molecular dynamics simulations of polymers reinforced with nanoscopic filler particles reveal the mechanisms by which nanofillers improve the toughness of the material. We find that the mobility of the nanofiller particle, rather than its surface area, controls its ability to dissipate energy. Our results show similarities between the toughening mechanisms observed in polymer nanocomposites and those postulated for biological structural materials such as spider silk and abalone adhesive.

  19. Programmed Switching of Single Polymer Conformation on DNA Origami.

    PubMed

    Krissanaprasit, Abhichart; Madsen, Mikael; Knudsen, Jakob Bach; Gudnason, Daniel; Surareungchai, Werasak; Birkedal, Victoria; Gothelf, Kurt Vesterager

    2016-02-23

    DNA nanotechnology offers precise geometrical control of the positioning of materials, and it is increasingly also being used in the development of nanomechanical devices. Here we describe the development of a nanomechanical device that allows switching of the position of a single-molecule conjugated polymer. The polymer is functionalized with short single-stranded (ss) DNA strands that extend from the backbone of the polymer and serve as handles. The DNA polymer conjugate can be aligned on DNA origami in three well-defined geometries (straight line, left-turned, and right-turned pattern) by DNA hybridization directed by single-stranded guiding strands and ssDNA tracks extending from the origami surface and polymer handle. We demonstrate switching of a conjugated organic polymer conformation between left- and right-turned conformations of the polymer on DNA origami based on toehold-mediated strand displacement. The switching is observed by atomic force microscopy and by Förster resonance energy transfer between the polymer and two different organic dyes positioned in close proximity to the respective patterns. Using this method, the polymer conformation can be switched six times successively. This controlled nanomechanical switching of conjugated organic polymer conformation demonstrates unique control of the shape of a single polymer molecule, and it may constitute a new component for the development of reconfigurable nanophotonic and nanoelectronic devices.

  20. South African court rejects country's new constitution.

    PubMed

    1996-09-20

    Fundamental principles designed to ensure that South Africa's new constitution upholds a wide range of individual rights and freedoms and establishes a responsive government with a balanced separation of powers, including recognition of the role of traditional tribal leadership, were adopted into the current interim constitution shortly before the 1994 free elections which brought Nelson Mandela and the African National Congress to power. In a judgement issued on September 6, 1996, South Africa's Constitutional Court rejected the country's new draft constitution, arguing that it failed to meet the standards of nine of the 34 principles established at the Kempton Park negotiations. The Constitutional Assembly is comprised of a joint meeting of the National Assembly and Senate. One of the court's major objections to the constitution concerned the proposed structure of rule, which was seen to give inadequate power to South Africa's nine provinces as compared with the national government. However, the bill of rights was almost entirely upheld. The bill would create a favorable environment for legalized abortion and guarantee a universal right of access to health care, including reproductive health services

  1. Interpretations of Polymer-Polymer Miscibility.

    ERIC Educational Resources Information Center

    Olabisi, Olagoke

    1981-01-01

    Discusses various aspects of polymeric mixtures, mixtures of structurally different homopolymers, copolymers, terpolymers, and the like. Defines concepts of polymer-polymer miscibility from practical and theoretical viewpoints, and ways of predicting such miscibility. (JN)

  2. Unexpected power-law stress relaxation of entangled ring polymers

    PubMed Central

    KAPNISTOS, M.; LANG, M.; PYCKHOUT-HINTZEN, W.; RICHTER, D.; CHO, D.; CHANG, T.

    2016-01-01

    After many years of intense research, most aspects of the motion of entangled polymers have been understood. Long linear and branched polymers have a characteristic entanglement plateau and their stress relaxes by chain reptation or branch retraction, respectively. In both mechanisms, the presence of chain ends is essential. But how do entangled polymers without ends relax their stress? Using properly purified high-molar-mass ring polymers, we demonstrate that these materials exhibit self-similar dynamics, yielding a power-law stress relaxation. However, trace amounts of linear chains at a concentration almost two decades below their overlap cause an enhanced mechanical response. An entanglement plateau is recovered at higher concentrations of linear chains. These results constitute an important step towards solving an outstanding problem of polymer science and are useful for manipulating properties of materials ranging from DNA to polycarbonate. They also provide possible directions for tuning the rheology of entangled polymers. PMID:18953345

  3. Confinement enhances dispersion in nanoparticle-polymer blend films.

    PubMed

    Chandran, Sivasurender; Begam, Nafisa; Padmanabhan, Venkat; Basu, J K

    2014-05-08

    Polymer nanocomposites constitute an important class of materials whose properties depend on the state of dispersion of the nanoparticles in the polymer matrix. Here we report the first observations of confinement-induced enhancement of dispersion in nanoparticle-polymer blend films. Systematic variation in the dispersion of nanoparticles with confinement for various compositions and matrix polymer chain dimensions has been observed. For fixed composition, strong reduction in glass transition temperature, Tg, is observed with decreasing blend-film thickness. The enhanced dispersion occurs without altering the polymer-particle interactions and seems to be driven by enhanced matrix-chain orientation propensity and a tendency to minimize the density gradients within the matrix. This implies the existence of two different mechanisms in polymer nanocomposites, which determines their state of dispersion and glass transition.

  4. Thin Polymer Films Containing Carbon Nanostructures

    NASA Astrophysics Data System (ADS)

    Paszkiewicz, S.; Piesowicz, E.; Irska, I.; Roslaniec, Z.; Szymczyk, A.; Pawelec, I.

    2016-05-01

    Within the framework of the presented paper, the research experiments were conducted on the preparation and characterization of polymer thin films containing carbon nanotubes, graphene derivatives and hybrid systems of both CNTs/graphene derivatives, in which condensation polymers constituted the matrix. The use of in situ synthesis allowed to obtain nanocomposites with a high degree of homogeneity, which is a key issue for further industrial applications, while the analysis of the physical properties of the obtained materials showed effect of the addition of carbon nanotubes and graphene derivatives on their structure, barrier properties and thermal and electrical conductivity.

  5. [Gene polymorphism and physical constitution theory: starting point of exploring syndromes of lung cancer].

    PubMed

    Su, Wan; Xu, Zhen-ye

    2010-01-01

    Physical constitution theory is an important part of traditional Chinese medicine theory. Physical constitution is associated with the incidence, development and prognosis of diseases. Gene polymorphism is a result of the interaction between internal and external environments during the human evolution, and it is the reason for differences in biological characteristics and disease susceptibility of individuals. Current status of the research on physical constitution theory, lung cancer syndromes and gene polymorphism are summarized in this paper. Exploring lung cancer syndromes from the point of view of gene polymorphism may reveal the scientific connotation of lung cancer syndromes, and provide new evidence and method for diagnosis of lung cancer.

  6. Direct characterization of polymer encapsulated CdSe/CdS/ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Zorn, Gilad; Dave, Shivang R.; Weidner, Tobias; Gao, Xiaohu; Castner, David G.

    2016-06-01

    Surface engineering advances of semiconductor quantum dots (QDs) have enabled their application to molecular labeling, disease diagnostics and tumor imaging. For biological applications, hydrophobic core/shell QDs are transferred into aqueous solutions through the incorporation of water-solubility imparting moieties, typically achieved via direct exchange of the native surface passivating ligands or indirectly through the adsorption of polymers. Although polymeric encapsulation has gained wide acceptance, there are few reports addressing the characterization of the adsorbed polymers and existing theoretical analyses are typically based on simple geometric models. In this work, we experimentally characterize and quantify water-soluble QDs prepared by adsorption of amphiphilic poly(maleic anhydride-alt-1-tetradecene) (PMAT, MW ~ 9000) onto commercially available CdSe/CdS/ZnS (CdSe/CdS/ZnS-PMAT). Using X-ray photoelectron spectroscopy (XPS) we determined that ~ 15 PMAT molecules are adsorbed onto each QD and sum frequency generation (SFG) vibrational spectra were utilized to investigate the mechanism of interaction between PMAT molecules and the QD surface. Importantly, when employed together, these techniques constitute a platform with which to investigate any polymer-nanoparticle complex in general.

  7. Computational Systems Chemical Biology

    PubMed Central

    Oprea, Tudor I.; May, Elebeoba E.; Leitão, Andrei; Tropsha, Alexander

    2013-01-01

    There is a critical need for improving the level of chemistry awareness in systems biology. The data and information related to modulation of genes and proteins by small molecules continue to accumulate at the same time as simulation tools in systems biology and whole body physiologically-based pharmacokinetics (PBPK) continue to evolve. We called this emerging area at the interface between chemical biology and systems biology systems chemical biology, SCB (Oprea et al., 2007). The overarching goal of computational SCB is to develop tools for integrated chemical-biological data acquisition, filtering and processing, by taking into account relevant information related to interactions between proteins and small molecules, possible metabolic transformations of small molecules, as well as associated information related to genes, networks, small molecules and, where applicable, mutants and variants of those proteins. There is yet an unmet need to develop an integrated in silico pharmacology / systems biology continuum that embeds drug-target-clinical outcome (DTCO) triplets, a capability that is vital to the future of chemical biology, pharmacology and systems biology. Through the development of the SCB approach, scientists will be able to start addressing, in an integrated simulation environment, questions that make the best use of our ever-growing chemical and biological data repositories at the system-wide level. This chapter reviews some of the major research concepts and describes key components that constitute the emerging area of computational systems chemical biology. PMID:20838980

  8. Computational systems chemical biology.

    PubMed

    Oprea, Tudor I; May, Elebeoba E; Leitão, Andrei; Tropsha, Alexander

    2011-01-01

    There is a critical need for improving the level of chemistry awareness in systems biology. The data and information related to modulation of genes and proteins by small molecules continue to accumulate at the same time as simulation tools in systems biology and whole body physiologically based pharmacokinetics (PBPK) continue to evolve. We called this emerging area at the interface between chemical biology and systems biology systems chemical biology (SCB) (Nat Chem Biol 3: 447-450, 2007).The overarching goal of computational SCB is to develop tools for integrated chemical-biological data acquisition, filtering and processing, by taking into account relevant information related to interactions between proteins and small molecules, possible metabolic transformations of small molecules, as well as associated information related to genes, networks, small molecules, and, where applicable, mutants and variants of those proteins. There is yet an unmet need to develop an integrated in silico pharmacology/systems biology continuum that embeds drug-target-clinical outcome (DTCO) triplets, a capability that is vital to the future of chemical biology, pharmacology, and systems biology. Through the development of the SCB approach, scientists will be able to start addressing, in an integrated simulation environment, questions that make the best use of our ever-growing chemical and biological data repositories at the system-wide level. This chapter reviews some of the major research concepts and describes key components that constitute the emerging area of computational systems chemical biology.

  9. Helix control in polymers

    PubMed Central

    Totsingan, Filbert; Jain, Vipul; Green, Mark M.

    2012-01-01

    The helix is a critical conformation exhibited by biological macromolecules and plays a key role in fundamental biological processes. Biological helical polymers exist in a single helical sense arising from the chiral effect of their primary units—for example, DNA and proteins adopt predominantly a right-handed helix conformation in response to the asymmetric conformational propensity of D-sugars and L-amino acids, respectively. In using these homochiral systems, nature blocks our observations of some fascinating aspects of the cooperativity in helical systems, although when useful for a specific purpose, “wrong” enantiomers may be incorporated in specific places. In synthetic helical systems, on the contrary, incorporation of non-racemic chirality is an additional burden, and the findings discussed in this review show that this burden may be considerably alleviated by taking advantage of the amplification of chirality, in which small chiral influences lead to large consequences. Peptide nucleic acid (PNA), which is a non-chiral synthetic DNA mimic, shows a cooperative response to a small chiral effect induced by a chiral amino acid, which is limited, however, due to the highly flexible nature of this oligomeric chimera. The lack of internal stereochemical bias is an important factor which makes PNA an ideal system to understand some cooperative features that are not directly accessible from DNA. PMID:22772039

  10. Hopping Diffusion of Nanoparticles in Polymer Matrices

    PubMed Central

    2016-01-01

    We propose a hopping mechanism for diffusion of large nonsticky nanoparticles subjected to topological constraints in both unentangled and entangled polymer solids (networks and gels) and entangled polymer liquids (melts and solutions). Probe particles with size larger than the mesh size ax of unentangled polymer networks or tube diameter ae of entangled polymer liquids are trapped by the network or entanglement cells. At long time scales, however, these particles can diffuse by overcoming free energy barrier between neighboring confinement cells. The terminal particle diffusion coefficient dominated by this hopping diffusion is appreciable for particles with size moderately larger than the network mesh size ax or tube diameter ae. Much larger particles in polymer solids will be permanently trapped by local network cells, whereas they can still move in polymer liquids by waiting for entanglement cells to rearrange on the relaxation time scales of these liquids. Hopping diffusion in entangled polymer liquids and networks has a weaker dependence on particle size than that in unentangled networks as entanglements can slide along chains under polymer deformation. The proposed novel hopping model enables understanding the motion of large nanoparticles in polymeric nanocomposites and the transport of nano drug carriers in complex biological gels such as mucus. PMID:25691803

  11. A constitutive theory of reacting electrolyte mixtures

    NASA Astrophysics Data System (ADS)

    Costa Reis, Martina; Wang, Yongqi; Bono Maurizio Sacchi Bassi, Adalberto

    2013-11-01

    A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).

  12. Constitutive apical membrane recycling in Aplysia enterocytes.

    PubMed

    Keeton, Robert Aaron; Runge, Steven William; Moran, William Michael

    2004-11-01

    In Aplysia californica enterocytes, alanine-stimulated Na+ absorption increases both apical membrane exocytosis and fractional capacitance (fCa; a measure of relative apical membrane surface area). These increases are thought to reduce membrane tension during periods of nutrient absorption that cause the enterocytes to swell osmotically. In the absence of alanine, exocytosis and fCa are constant. These findings imply equal rates of constitutive endocytosis and exocytosis and constitutive recycling of the apical plasma membrane. Thus, the purpose of this study was to confirm and determine the relative extent of constitutive apical membrane recycling in Aplysia enterocytes. Biotinylated lectins are commonly used to label plasma membranes and to investigate plasma membrane recycling. Of fourteen biotinylated lectins tested, biotinylated wheat germ agglutinin (bWGA) bound preferentially to the enterocytes apical surface. Therefore, we used bWGA, avidin D (which binds tightly to biotin), and the UV fluorophore 7-amino-4-methylcoumarin-3-acetic acid (AMCA)-conjugated avidin D to assess the extent of constitutive apical membrane recycling. A temperature-dependent (20 vs. 4 degrees C) experimental protocol employed the use of two tissues from each of five snails and resulted in a approximately 60% difference in apical surface fluorescence intensity. Because the extent of membrane recycling is proportional to the difference in surface fluorescence intensity, this difference reveals a relatively high rate of constitutive apical membrane recycling in Aplysia enterocytes.

  13. Health care law versus constitutional law.

    PubMed

    Hall, Mark A

    2013-04-01

    National Federation of Independent Business v. Sebelius, the Supreme Court's ruling on the Patient Protection and Affordable Care Act, is a landmark decision - both for constitutional law and for health care law and policy. Others will study its implications for constitutional limits on a range of federal powers beyond health care. This article considers to what extent the decision is also about health care law, properly conceived. Under one view, health care law is the subdiscipline that inquires how courts and government actors take account of the special features of medicine that make legal or policy issues especially problematic - rather than regarding health care delivery and finance more generically, like most any other economic or social enterprise. Viewed this way, the opinions from the Court's conservative justices are mainly about general constitutional law principles. In contrast, Justice Ruth Bader Ginsburg's dissenting opinion for the four more liberal justices is just as much about health care law as it is about constitutional law. Her opinion gives detailed attention to the unique features of health care finance and delivery in order to inform her analysis of constitutional precedents and principles. Thus, the Court's multiple opinions give a vivid depiction of the compelling contrasts between communal versus individualistic conceptions of caring for those in need, and between health care and health insurance as ordinary commodities versus ones that merit special economic, social, and legal status.

  14. Clickable Antifouling Polymer Brushes for Polymer Pen Lithography.

    PubMed

    Bog, Uwe; de Los Santos Pereira, Andres; Mueller, Summer L; Havenridge, Shana; Parrillo, Viviana; Bruns, Michael; Holmes, Andrea E; Rodriguez-Emmenegger, Cesar; Fuchs, Harald; Hirtz, Michael

    2017-03-23

    Protein-repellent reactive surfaces that promote localized specific binding are highly desirable for applications in the biomedical field. Nonspecific adhesion will compromise the function of bioactive surfaces, leading to ambiguous results of binding assays and negating the binding specificity of patterned cell-adhesive motives. Localized specific binding is often achieved by attaching a linker to the surface, and the other side of the linker is used to bind specifically to a desired functional agent, as e.g. proteins, antibodies, and fluorophores, depending on the function required by the application. We present a protein-repellent polymer brush enabling highly specific covalent surface immobilization of biorecognition elements by strain-promoted alkyne-azide cycloaddition click chemistry for selective protein adhesion. The protein-repellent polymer brush is functionalized by highly localized molecular binding sites in the low micrometer range using polymer pen lithography (PPL). Because of the massive parallelization of writing pens, the tunable PPL printed patterns can span over square centimeter areas. The selective binding of the protein streptavidin to these surface sites is demonstrated while the remaining polymer brush surface is resisting nonspecific adsorption without any prior blocking by bovine serum albumin (BSA). In contrast to the widely used BSA blocking, the reactive polymer brushes are able to significantly reduce nonspecific protein adsorption, which is the cause of biofouling. This was achieved for solutions of single proteins as well as complex biological fluids. The remarkable fouling resistance of the polymer brushes has the potential to improve the multiplexing capabilities of protein probes and therefore impact biomedical research and applications.

  15. Rate Dependent Deformation and Strength Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1999-01-01

    A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic strain. Additionally, modifications to the polymer constitutive model are discussed in which pressure dependence is incorporated into the equations in order to improve the calculation of constituent and composite shear stresses. The Hashin failure criterion is implemented into the analysis method to allow for the calculation of ply level failure stresses. The deformation response and failure stresses for two representative uniaxial polymer matrix composites, IM7/977-2 and AS4-PEEK, are predicted for varying strain rates and fiber orientations. The predicted results compare favorably to experimentally obtained values.

  16. Nanotribology of charged polymer brushes

    NASA Astrophysics Data System (ADS)

    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.

  17. The regularity theory of mechanistic constitution and a methodology for constitutive inference.

    PubMed

    Harbecke, Jens

    2015-12-01

    This paper discusses a Boolean method for establishing constitutive regularity statements which, according to the regularity theory of mechanistic constitution, form the core of any mechanistic explanation in neuroscience. After presenting the regularity definition for the constitution relation, the paper develops a set of inference rules allowing one to establish constitutive hypotheses in light of certain kinds of empirical evidence. The general methodology consisting of these rules is characterized as having formed the basis of many successful explanatory projects in neuroscience. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Constitutive model development for isotropic materials

    NASA Technical Reports Server (NTRS)

    Kaufman, A.

    1982-01-01

    The objective is to develop a unified constitutive model for finite-element structural analysis of turbine engine hot section components. This effort constitutes a different approach for nonlinear finite-element computer codes which were heretofore based on classical inelastic methods. A unified constitutive theory will avoid the simplifying assumptions of classical theory and should more accurately represent the behavior of superalloy materials under cyclic loading conditions and high temperature environments. Model development will be directed toward isotropic, cast nickel-base alloys used for aircooled turbine blades and vanes. The contractor will select a base material for model development and an alternate material for verification purposes from a list of three alloys specified by NASA. The candidate alloys represent a cross-section of turbine blade and vane materials of interest to both large and small size engine manufacturers. Material stock for the base and alternate materials will be supplied to the Contractor by the government.

  19. A survey of unified constitutive theories

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.; Walker, K. P.

    1985-01-01

    The state of the art of time temperature dependent elastic viscoplastic constitutive theories which are based on the unified approach werre assessed. This class of constitutive theories is characterized by the use of kinetic equations and internal variables with appropriate evolutionary equations for treating all aspects of inelastic deformation including plasticity, creep, and stress relaxation. More than 10 such unified theories which are shown to satisfy the uniqueness and stability criteria imposed by Drucker's postulate and Ponter's inequalities are identified. The theories are compared for the types of flow law, kinetic equation, evolutionary equation of the internal variables, and treatment of temperature dependence. The similarities and differences of these theories are outlined in terms of mathematical formulations and illustrated by comparisons of theoretical calculations with experimental results which include monotonic stress-strain curves, cyclic hysteresis loops, creep and stress relaxation rates, and thermomechanical loops. Numerical methods used for integrating these stiff time temperature dependent constitutive equations are reviewed.

  20. Composites comprising biologically-synthesized nanomaterials

    DOEpatents

    Curran, Seamus; Dias, Sampath; Blau, Werner; Wang, Jun; Oremland, Ronald S; Baesman, Shaun

    2013-04-30

    The present disclosure describes composite materials containing a polymer material and a nanoscale material dispersed in the polymer material. The nanoscale materials may be biologically synthesized, such as tellurium nanorods synthesized by Bacillus selenitireducens. Composite materials of the present disclosure may have optical limiting properties and find use in optical limiting devices.

  1. Shape memory polymers

    DOEpatents

    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.

  2. Shape memory polymers

    DOEpatents

    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.

  3. Molecular karyotyping in human constitutional cytogenetics.

    PubMed

    Sanlaville, Damien; Lapierre, Jean-Michel; Turleau, Catherine; Coquin, Aurélie; Borck, Guntram; Colleaux, Laurence; Vekemans, Michel; Romana, Serge Pierrick

    2005-01-01

    Using array CGH it is possible to detect very small genetic imbalances anywhere in the genome. Its usefulness has been well documented in cancer and more recently in constitutional disorders. In particular it has been used to detect interstitial and subtelomeric submicroscopic imbalances, to characterize their size at the molecular level and to define the breakpoints of chromosomal translocation. Here, we review the various applications of array CGH in constitutional cytogenetics. This technology remains expensive and the existence of numerous sequence polymorphisms makes its interpretation difficult. The challenge today is to transfer this technology in the clinical setting.

  4. Thermoelastic constitutive equations for chemically hardening materials

    NASA Technical Reports Server (NTRS)

    Shaffer, B. W.; Levitsky, M.

    1974-01-01

    Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

  5. Constitutional aspects of economic law enforcement

    SciTech Connect

    Tundermann, D.W.

    1980-01-01

    Economic remedies for violations of environmental standards provide a better administrative approach than civil penalties based on more traditional discretionary criteria. Economic penalties are not subject to the constitutional requirements that limit the procedures for criminal penalties. Economic penalties also provide a constitutionally permissible way of accruing liability during litigation. These penalties are large enough to eliminate the benefits of delayed compliance and unnecessary litigation; however, they do not alter the rights of judicial review. Agencies can determine economic penalties with more objectivity and accuracy than under traditional penalty schemes.

  6. Biologically inspired toys using artificial muscles

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.

    2001-01-01

    Recent developments in electroactive polymers, so-called artificial muscles, could one day be used to make bionics possible. Meanwhile, as this technology evolves novel mechanisms are expected to emerge that are biologically inspired.

  7. Biologically inspired toys using artificial muscles

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.

    2001-01-01

    Recent developments in electroactive polymers, so-called artificial muscles, could one day be used to make bionics possible. Meanwhile, as this technology evolves novel mechanisms are expected to emerge that are biologically inspired.

  8. Synthetic strategies for the generation of molecularly imprinted organic polymers.

    PubMed

    Mayes, A G; Whitcombe, M J

    2005-12-06

    Molecular imprinting is a method of inducing molecular recognition properties in synthetic polymers in response to the presence of a template species during formation of the three-dimensional structure of the polymer. The molecularly imprinted polymers (MIPs) prepared in this way have been termed "plastic antibodies" and combine the robustness of the polymer scaffold with binding properties more readily associated with biological receptors. Smart polymers of this type may find applications in drug delivery, controlled release and monitoring of drug and metabolite concentrations. In this review the main synthetic strategies used in the preparation of imprinted organic polymers are described in terms of the chemical principles used in the templating step. These are illustrated with examples taken from the literature and are classified as covalent, semi-covalent, non-covalent, metal-mediated and non-polar. Finally strategies for the selection of monomers, optimisation and modification of the properties of imprinted polymers are reviewed.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Thermoelectric Polymers and their Elastic Aerogels.

    PubMed

    Khan, Zia Ullah; Edberg, Jesper; Hamedi, Mahiar Max; Gabrielsson, Roger; Granberg, Hjalmar; Wågberg, Lars; Engquist, Isak; Berggren, Magnus; Crispin, Xavier

    2016-06-01

    Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin.

  11. Optically responsive supramolecular polymer glasses

    NASA Astrophysics Data System (ADS)

    Balkenende, Diederik W. R.; Monnier, Christophe A.; Fiore, Gina L.; Weder, Christoph

    2016-03-01

    The reversible and dynamic nature of non-covalent interactions between the constituting building blocks renders many supramolecular polymers stimuli-responsive. This was previously exploited to create thermally and optically healable polymers, but it proved challenging to achieve high stiffness and good healability. Here we present a glass-forming supramolecular material that is based on a trifunctional low-molecular-weight monomer ((UPyU)3TMP). Carrying three ureido-4-pyrimidinone (UPy) groups, (UPyU)3TMP forms a dynamic supramolecular polymer network, whose properties are governed by its cross-linked architecture and the large content of the binding motif. This design promotes the formation of a disordered glass, which, in spite of the low molecular weight of the building block, displays typical polymeric behaviour. The material exhibits a high stiffness and offers excellent coating and adhesive properties. On account of reversible dissociation and the formation of a low-viscosity liquid upon irradiation with ultraviolet light, rapid optical healing as well as (de)bonding on demand is possible.

  12. Optically responsive supramolecular polymer glasses

    PubMed Central

    Balkenende, Diederik W. R.; Monnier, Christophe A.; Fiore, Gina L.; Weder, Christoph

    2016-01-01

    The reversible and dynamic nature of non-covalent interactions between the constituting building blocks renders many supramolecular polymers stimuli-responsive. This was previously exploited to create thermally and optically healable polymers, but it proved challenging to achieve high stiffness and good healability. Here we present a glass-forming supramolecular material that is based on a trifunctional low-molecular-weight monomer ((UPyU)3TMP). Carrying three ureido-4-pyrimidinone (UPy) groups, (UPyU)3TMP forms a dynamic supramolecular polymer network, whose properties are governed by its cross-linked architecture and the large content of the binding motif. This design promotes the formation of a disordered glass, which, in spite of the low molecular weight of the building block, displays typical polymeric behaviour. The material exhibits a high stiffness and offers excellent coating and adhesive properties. On account of reversible dissociation and the formation of a low-viscosity liquid upon irradiation with ultraviolet light, rapid optical healing as well as (de)bonding on demand is possible. PMID:26983805

  13. Materials comprising polydienes and hydrophilic polymers and related methods

    DOEpatents

    Mays, Jimmy W [Knoxville, TN; Deng, Suxiang [Knoxville, TN; Mauritz, Kenneth A [Hattiesburg, MS; Hassan, Mohammad K [Hattiesburg, MS; Gido, Samuel P [Hadley, MA

    2011-11-22

    Materials prepared from polydienes, such as poly(cyclohexadiene), and hydrophilic polymers, such as poly(alkylene oxide), are described. Methods of making the materials and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization are also provided. The materials can be crosslinked and sulfonated, and can include copolymers and polymer blends.

  14. Reasons for using polymer blends in the electrospinning process

    NASA Astrophysics Data System (ADS)

    Martinova, Lenka; Lubasova, Daniela

    2012-11-01

    Polymer blends can be very effective for the processing of nanofibers, especially for the novel electrospinning process of Nanospider™ (Jirsak et al., 2005, www.nanospider.cz), offering the realistic potential for industrial production of nanofiber sheets. Polymer blending is designed to generate materials with optimized chemical, structural, mechanical, morphological and biological properties.

  15. Multifunctional and biologically active matrices from multicomponent polymeric solutions

    NASA Technical Reports Server (NTRS)

    Kiick, Kristi L. (Inventor); Yamaguchi, Nori (Inventor)

    2010-01-01

    The present invention relates to a biologically active functionalized electrospun matrix to permit immobilization and long-term delivery of biologically active agents. In particular the invention relates to a functionalized polymer matrix comprising a matrix polymer, a compatibilizing polymer and a biomolecule or other small functioning molecule. In certain aspects the electrospun polymer fibers comprise at least one biologically active molecule functionalized with low molecular weight heparin. Examples of active molecules that may be used with the multicomponent polymer of the invention include, for example, a drug, a biopolymer, for example a growth factor, a protein, a peptide, a nucleotide, a polysaccharide, a biological macromolecule or the like. The invention is further directed to the formation of functionalized crosslinked matrices, such as hydrogels, that include at least one functionalized compatibilizing polymer capable of assembly.

  16. Chemical and Biological Kinetics

    NASA Astrophysics Data System (ADS)

    Emanuel', N. M.

    1981-10-01

    Examples of the application of the methods and ideas of chemical kinetics in various branches of chemistry and biology are considered and the results of studies on the kinetics and mechanisms of autoxidation and inhibited and catalysed oxidation of organic substances in the liquid phase are surveyed. Problems of the kinetics of the ageing of polymers and the principles of their stabilisation are discussed and certain trends in biological kinetics (kinetics of tumour growth, kinetic criteria of the effectiveness of chemotherapy, problems of gerontology, etc.) are considered. The bibliography includes 281 references.

  17. 3 CFR 8418 - Proclamation 8418 of September 16, 2009. Constitution Day and Citizenship Day, Constitution Week...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., that we are each endowed with certain unalienable rights. As the beneficiaries of these rights, all... Constitution and teach younger generations about its contents and history. By fulfilling civic duties, engaging... can better our country and breathe life into the freedoms established in the Constitution. The right...

  18. Constitutive laws, tensorial invariance and chocolate cake

    NASA Astrophysics Data System (ADS)

    Rundle, John B.; Passman, S. L.

    1982-04-01

    Although constitutive modeling is a well-established branch of mathematics which has found wide industrial application, geophysicists often do not take full advantage of its known results. We present a synopsis of the theory of constitutive modeling, couched in terms of the ‘simple material’, which has been extensively studied and is complex enough to include most of the correct models proposed to describe the behavior of geological materials. Critical in the development of the theory are various invariance requirements, the principal ones being coordinate invariance, peer group invariance (isotropy), and frame-indifference. Each places distinet restrictions on constitutive equations. A noncomprehensive list of properly invariant and commonly used constitutive equations is given. To exemplify use of the equations, we consider two problems in detail: steady extension, which models the commonly performed constant strain rate triaxial test, and simple shearing. We note that each test is so restricted kinematically that only the most trivial aspects of material behavior are manifested in these tests, no matter how complex the material. Furthermore, the results of one test do not generally determine the results of the other.

  19. The Constitution: Burkeian, Brandeisian and Borkian Perspectives.

    ERIC Educational Resources Information Center

    Ewbank, Henry L.

    1996-01-01

    Argues that Kenneth Burke's rhetorical theory is exemplified in the statements of Justice Louis Brandeis, whose concept of "the living law" explores the contemporary scene as ground for judicial review. Contends that Robert Bork's search for "neutral principles" in Constitutional words ignores the symbolic and dialectical…

  20. School Choice and State Constitutions' Religion Clauses

    ERIC Educational Resources Information Center

    Komer, Richard D.

    2009-01-01

    After the U.S. Supreme Court's decision in "Zelman v. Simmons-Harris," only state religion clauses represent a potential constitutional bar to the inclusion of religious options in properly designed school choice programs. The two most significant are compelled support clauses and Blaine Amendments. Both are frequently misinterpreted by state…