Evaluation of urban river landscape design rationality based on AHP

Directory of Open Access Journals (Sweden)

Qiao Lifang

2008-12-01

Full Text Available An evaluation model for the rationality of the landscape design of urban rivers was established with the analytic hierarchy process (AHP method so as to provide a foundation for updating the landscape design of urban rivers. The evaluation system was divided into four layers, including the target layer, the comprehensive layer, the element layer, and the index layer. Each layer was made of different indices. The evaluation standards for each index were also given in this paper. This evaluation model was proved tenable through its application to the landscape design rationality evaluation of the Weihe River in Xinxiang City of Henan Province. The results show that the water quality, space, activity, facility, community, width of vegetation, sense of beauty and water content are among the most influential factors and should be considered the main basis for evaluating the rationality of the landscape design of urban rivers.

Intrinsically Microporous Polymer Membranes for High Performance Gas Separation

KAUST Repository

Swaidan, Raja

2014-01-01

This dissertation addresses the rational design of intrinsically microporous solutionprocessable polyimides and ladder polymers for highly permeable and highly selective gas transport in cornerstone applications of membrane-based gas separation

Machine learning in the rational design of antimicrobial peptides.

Science.gov (United States)

Rondón-Villarreal, Paola; Sierra, Daniel A; Torres, Rodrigo

2014-01-01

One of the most important public health issues is the microbial and bacterial resistance to conventional antibiotics by pathogen microorganisms. In recent years, many researches have been focused on the development of new antibiotics. Among these, antimicrobial peptides (AMPs) have raised as a promising alternative to combat antibioticresistant microorganisms. For this reason, many theoretical efforts have been done in the development of new computational tools for the rational design of both better and effective AMPs. In this review, we present an overview of the rational design of AMPs using machine learning techniques and new research fields.

Rational Design of an Ultrasensitive Quorum-Sensing Switch.

Science.gov (United States)

Zeng, Weiqian; Du, Pei; Lou, Qiuli; Wu, Lili; Zhang, Haoqian M; Lou, Chunbo; Wang, Hongli; Ouyang, Qi

2017-08-18

One of the purposes of synthetic biology is to develop rational methods that accelerate the design of genetic circuits, saving time and effort spent on experiments and providing reliably predictable circuit performance. We applied a reverse engineering approach to design an ultrasensitive transcriptional quorum-sensing switch. We want to explore how systems biology can guide synthetic biology in the choice of specific DNA sequences and their regulatory relations to achieve a targeted function. The workflow comprises network enumeration that achieves the target function robustly, experimental restriction of the obtained candidate networks, global parameter optimization via mathematical analysis, selection and engineering of parts based on these calculations, and finally, circuit construction based on the principles of standardization and modularization. The performance of realized quorum-sensing switches was in good qualitative agreement with the computational predictions. This study provides practical principles for the rational design of genetic circuits with targeted functions.

Development of a model for the rational design of molecular imprinted polymer: Computational approach for combined molecular dynamics/quantum mechanics calculations

International Nuclear Information System (INIS)

Dong Cunku; Li Xin; Guo Zechong; Qi Jingyao

2009-01-01

A new rational approach for the preparation of molecularly imprinted polymer (MIP) based on the combination of molecular dynamics (MD) simulations and quantum mechanics (QM) calculations is described in this work. Before performing molecular modeling, a virtual library of functional monomers was created containing forty frequently used monomers. The MD simulations were first conducted to screen the top three monomers from virtual library in each porogen-acetonitrile, chloroform and carbon tetrachloride. QM simulations were then performed with an aim to select the optimum monomer and progen solvent in which the QM simulations were carried out; the monomers giving the highest binding energies were chosen as the candidate to prepare MIP in its corresponding solvent. The acetochlor, a widely used herbicide, was chosen as the target analyte. According to the theoretical calculation results, the MIP with acetochlor as template was prepared by emulsion polymerization method using N,N-methylene bisacrylamide (MBAAM) as functional monomer and divinylbenzene (DVB) as cross-linker in chloroform. The synthesized MIP was then tested by equilibrium-adsorption method, and the MIP demonstrated high removal efficiency to the acetochlor. Mulliken charge distribution and 1 H NMR spectroscopy of the synthesized MIP provided insight on the nature of recognition during the imprinting process probing the governing interactions for selective binding site formation at a molecular level. We think the computer simulation method first proposed in this paper is a novel and reliable method for the design and synthesis of MIP.

From bricolage to BioBricks™: Synthetic biology and rational design.

Science.gov (United States)

Lewens, Tim

2013-12-01

Synthetic biology is often described as a project that applies rational design methods to the organic world. Although humans have influenced organic lineages in many ways, it is nonetheless reasonable to place synthetic biology towards one end of a continuum between purely 'blind' processes of organic modification at one extreme, and wholly rational, design-led processes at the other. An example from evolutionary electronics illustrates some of the constraints imposed by the rational design methodology itself. These constraints reinforce the limitations of the synthetic biology ideal, limitations that are often freely acknowledged by synthetic biology's own practitioners. The synthetic biology methodology reflects a series of constraints imposed on finite human designers who wish, as far as is practicable, to communicate with each other and to intervene in nature in reasonably targeted and well-understood ways. This is better understood as indicative of an underlying awareness of human limitations, rather than as expressive of an objectionable impulse to mastery over nature. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hybrid Polymer-Network Hydrogels with Tunable Mechanical Response

Directory of Open Access Journals (Sweden)

Sebastian Czarnecki

2016-03-01

Full Text Available Hybrid polymer-network gels built by both physical and covalent polymer crosslinking combine the advantages of both these crosslinking types: they exhibit high mechanical strength along with excellent fracture toughness and extensibility. If these materials are extensively deformed, their physical crosslinks can break such that strain energy is dissipated and irreversible fracturing is restricted to high strain only. This mechanism of energy dissipation is determined by the kinetics and thermodynamics of the physical crosslinking contribution. In this paper, we present a poly(ethylene glycol (PEG based material toolkit to control these contributions in a rational and custom fashion. We form well-defined covalent polymer-network gels with regularly distributed additional supramolecular mechanical fuse links, whose strength of connectivity can be tuned without affecting the primary polymer-network composition. This is possible because the supramolecular fuse links are based on terpyridine–metal complexation, such that the mere choice of the fuse-linking metal ion adjusts their kinetics and thermodynamics of complexation–decomplexation, which directly affects the mechanical properties of the hybrid gels. We use oscillatory shear rheology to demonstrate this rational control and enhancement of the mechanical properties of the hybrid gels. In addition, static light scattering reveals their highly regular and well-defined polymer-network structures. As a result of both, the present approach provides an easy and reliable concept for preparing hybrid polymer-network gels with rationally designed properties.

Design of 2-D rational digital filters

International Nuclear Information System (INIS)

Harris, D.B

1981-01-01

A novel 2-D rational filter design technique is presented which makes use of a reflection coefficient function (RCF) representation for the filter transfer function. The design problem is formulated in the frequency domain. A least-square error criterion is used though the usual error measure is augmented with barrier functions. These act to restrict the domain of approximation to the set of stable filters. Construction of suitable barrier functions is facilitated by the RCF characterization

Polymer deformation and filling modes during microembossing

Science.gov (United States)

Rowland, Harry D.; King, William P.

2004-12-01

This work investigates the initial stages of polymer deformation during hot embossing micro-manufacturing at processing temperatures near the glass transition temperature (Tg) of polymer films having sufficient thickness such that polymer flow is not supply limited. Several stages of polymer flow can be observed by employing stamp geometries of various widths and varying imprint conditions of time and temperature to modulate polymer viscosity. Experiments investigate conditions affecting cavity filling phenomena, including apparent polymer viscosity. Stamps with periodic ridges of height and width 4 µm and periodicity 30, 50 and 100 µm emboss trenches into polymethyl methacrylate films at Tg - 10 °C time, temperature and load are correlated with replicated polymer shape, height and imprinted area. Polymer replicates are measured by atomic force microscopy and inspected by scanning electron microscopy. Cavity size and the temperature dependence of polymer viscosity significantly influence the nature of polymer deformation in hot embossing micro-manufacturing and must be accounted for in rational process design.

Polymers designed for laser ablation-influence of photochemical properties

International Nuclear Information System (INIS)

Lippert, T.; Dickinson, J.T.; Hauer, M.; Kopitkovas, G.; Langford, S.C.; Masuhara, H.; Nuyken, O.; Robert, J.; Salmio, H.; Tada, T.; Tomita, K.; Wokaun, A.

2002-01-01

The ablation characteristics of various polymers were studied at low and high fluences. The polymers can be divided into three groups, i.e. polymers containing triazene and ester groups, the same polymers without the triazene group, and polyimide as reference polymer. At high fluences similar ablation parameters, i.e. etch rates and effective absorption coefficients, were obtained for all polymers. The main difference is the absence of carbon deposits for the designed polymers. At low fluences (at 308 nm) very pronounced differences are detected. The polymers containing the photochemically most active group (triazene) exhibit the lowest threshold of ablation (as low as 25 mJ cm -2 ) and the highest etch rates (up to 3 μm/pulse), followed by the designed polyesters and then polyimide. The laser-induced decomposition of the designed polymers was studied by nanosecond-interferometry. Only the triazene-polymer reveals etching without any sign of surface swelling, which is observed for all other polymers. The etching of the triazene-polymer starts and ends with the laser pulse, clearly indicating photochemical etching. The triazene-polymer was also studied by time-of-flight mass spectrometry (TOF-MS). The intensities of the ablation fragments show pronounced differences between irradiation at the absorption band of the triazene group (308 nm) and irradiation at a shorter wavelength (248 nm)

Computer-aided polymer design using group contribution plus property models

DEFF Research Database (Denmark)

Satyanarayana, Kavitha Chelakara; Abildskov, Jens; Gani, Rafiqul

2009-01-01

. Polymer repeat unit property prediction models are required to calculate the properties of the generated repeat units. A systematic framework incorporating recently developed group contribution plus (GC(+)) models and an extended CAMD technique to include design of polymer repeat units is highlighted...... in this paper. The advantage of a GC(+) model in CAMD applications is that a very large number of polymer structures can be considered even though some of the group parameters may not be available. A number of case studies involving different polymer design problems have been solved through the developed......The preliminary step for polymer product design is to identify the basic repeat unit structure of the polymer that matches the target properties. Computer-aided molecular design (CAMD) approaches can be applied for generating the polymer repeat unit structures that match the required constraints...

Refolding of proteins from inclusion bodies: rational design and recipes.

Science.gov (United States)

Basu, Anindya; Li, Xiang; Leong, Susanna Su Jan

2011-10-01

The need to develop protein biomanufacturing platforms that can deliver proteins quickly and cost-effectively is ever more pressing. The rapid rate at which genomes can now be sequenced demands efficient protein production platforms for gene function identification. There is a continued need for the biotech industry to deliver new and more effective protein-based drugs to address new diseases. Bacterial production platforms have the advantage of high expression yields, but insoluble expression of many proteins necessitates the development of diverse and optimised refolding-based processes. Strategies employed to eliminate insoluble expression are reviewed, where it is concluded that inclusion bodies are difficult to eliminate for various reasons. Rational design of refolding systems and recipes are therefore needed to expedite production of recombinant proteins. This review article discusses efforts towards rational design of refolding systems and recipes, which can be guided by the development of refolding screening platforms that yield both qualitative and quantitative information on the progression of a given refolding process. The new opportunities presented by light scattering technologies for developing rational protein refolding buffer systems which in turn can be used to develop new process designs armed with better monitoring and controlling functionalities are discussed. The coupling of dynamic and static light scattering methodologies for incorporation into future bioprocess designs to ensure delivery of high-quality refolded proteins at faster rates is also discussed.

Ionic Liquids in Polymer Design: From Energy to Health

Science.gov (United States)

2016-10-19

of Papers published in non peer- reviewed journals: Final Report: Ionic Liquids in Polymer Design: From Energy to Health Report Title ACS Symposium...SECURITY CLASSIFICATION OF: ACS Symposium: Ionic Liquids in Polymer Design: From Energy to Health at Fall 2015 ACS Meeting in Boston, MA The...combination of ionic liquids and polymers has emerged as an active field of exploration in polymer science, where new materials have be realized for

Standby Gasoline Rationing Plan. Contingency gasoline rationing regulations

Energy Technology Data Exchange (ETDEWEB)

1979-02-01

The Economic Regulatory Administration issues final rules with respect to standby gasoline rationing. The plan is designed for and would be used only in the event of a severe gasoline shortage. The plan provides that eligibility for ration allotments will be primarily on the basis of motor vehicle registrations. DOE will mail government ration checks to the parties named in a national vehicle registration file to be maintained by DOE. Ration recipients may cash these checks for ration coupons at various designated coupon issuance points. Retail outlets and other suppliers will be required to redeem the ration coupons received in exchange for gasoline sold. Supplemental gas will be given to high-priority activities. A ration banking system will be established with two separate and distinct of ration accounts: retail outlets and other suppliers will open redemption accounts for the deposit of redeemed ration rights; and individuals or firms may open ration rights accounts, which will operate in much the same manner as monetary checking accounts. A white market will be permitted for the sale of transfer of ration rights. A percentage of the total ration rights to be issued will be reserved for distribution to the states as a State Ration Reserve, to be used by the states primarily for the relief of hardship. A National Ration Reserave will also be established. All sections of the Standby Gasoline Rationing Regulations are analyzed. (MCW)

Understanding Toughness in Bioinspired Cellulose Nanofibril/Polymer Nanocomposites.

Science.gov (United States)

Benítez, Alejandro J; Lossada, Francisco; Zhu, Baolei; Rudolph, Tobias; Walther, Andreas

2016-07-11

Cellulose nanofibrils (CNFs) are considered next generation, renewable reinforcements for sustainable, high-performance bioinspired nanocomposites uniting high stiffness, strength and toughness. However, the challenges associated with making well-defined CNF/polymer nanopaper hybrid structures with well-controlled polymer properties have so far hampered to deduce a quantitative picture of the mechanical properties space and deformation mechanisms, and limits the ability to tune and control the mechanical properties by rational design criteria. Here, we discuss detailed insights on how the thermo-mechanical properties of tailor-made copolymers govern the tensile properties in bioinspired CNF/polymer settings, hence at high fractions of reinforcements and under nanoconfinement conditions for the polymers. To this end, we synthesize a series of fully water-soluble and nonionic copolymers, whose glass transition temperatures (Tg) are varied from -60 to 130 °C. We demonstrate that well-defined polymer-coated core/shell nanofibrils form at intermediate stages and that well-defined nanopaper structures with tunable nanostructure arise. The systematic correlation between the thermal transitions in the (co)polymers, as well as its fraction, on the mechanical properties and deformation mechanisms of the nanocomposites is underscored by tensile tests, SEM imaging of fracture surfaces and dynamic mechanical analysis. An optimum toughness is obtained for copolymers with a Tg close to the testing temperature, where the soft phase possesses the best combination of high molecular mobility and cohesive strength. New deformation modes are activated for the toughest compositions. Our study establishes quantitative structure/property relationships in CNF/(co)polymer nanopapers and opens the design space for future, rational molecular engineering using reversible supramolecular bonds or covalent cross-linking.

Molecular and macro-scale analysis of enzyme-crosslinked silk hydrogels for rational biomaterial design.

Science.gov (United States)

McGill, Meghan; Coburn, Jeannine M; Partlow, Benjamin P; Mu, Xuan; Kaplan, David L

2017-11-01

Silk fibroin-based hydrogels have exciting applications in tissue engineering and therapeutic molecule delivery; however, their utility is dependent on their diffusive properties. The present study describes a molecular and macro-scale investigation of enzymatically-crosslinked silk fibroin hydrogels, and demonstrates that these systems have tunable crosslink density and diffusivity. We developed a liquid chromatography tandem mass spectroscopy (LC-MS/MS) method to assess the quantity and order of covalent tyrosine crosslinks in the hydrogels. This analysis revealed between 28 and 56% conversion of tyrosine to dityrosine, which was dependent on the silk concentration and reactant concentration. The crosslink density was then correlated with storage modulus, revealing that both crosslinking and protein concentration influenced the mechanical properties of the hydrogels. The diffusive properties of the bulk material were studied by fluorescence recovery after photobleaching (FRAP), which revealed a non-linear relationship between silk concentration and diffusivity. As a result of this work, a model for synthesizing hydrogels with known crosslink densities and diffusive properties has been established, enabling the rational design of silk hydrogels for biomedical applications. Hydrogels from naturally-derived silk polymers offer versitile opportunities in the biomedical field, however, their design has largely been an empirical process. We present a fundamental study of the crosslink density, storage modulus, and diffusion behavior of enzymatically-crosslinked silk hydrogels to better inform scaffold design. These studies revealed unexpected non-linear trends in the crosslink density and diffusivity of silk hydrogels with respect to protein concentration and crosslink reagent concentration. This work demonstrates the tunable diffusivity and crosslinking in silk fibroin hydrogels, and enables the rational design of biomaterials. Further, the characterization methods

Design of nanocarriers for nanoscale drug delivery to enhance cancer treatment using hybrid polymer and lipid building blocks.

Science.gov (United States)

Zhang, Rui Xue; Ahmed, Taksim; Li, Lily Yi; Li, Jason; Abbasi, Azhar Z; Wu, Xiao Yu

2017-01-26

Polymer-lipid hybrid nanoparticles (PLN) are an emerging nanocarrier platform made from building blocks of polymers and lipids. PLN integrate the advantages of biomimetic lipid-based nanoparticles (i.e. solid lipid nanoparticles and liposomes) and biocompatible polymeric nanoparticles. PLN are constructed from diverse polymers and lipids and their numerous combinations, which imparts PLN with great versatility for delivering drugs of various properties to their nanoscale targets. PLN can be classified into two types based on their hybrid nanoscopic structure and assembly methods: Type-I monolithic matrix and Type-II core-shell systems. This article reviews the history of PLN development, types of PLN, lipid and polymer candidates, fabrication methods, and unique properties of PLN. The applications of PLN in delivery of therapeutic or imaging agents alone or in combination for cancer treatment are summarized and illustrated with examples. Important considerations for the rational design of PLN for advanced nanoscale drug delivery are discussed, including selection of excipients, synthesis processes governing formulation parameters, optimization of nanoparticle properties, improvement of particle surface functionality to overcome macroscopic, microscopic and cellular biological barriers. Future directions and potential clinical translation of PLN are also suggested.

RECENT ADVANCES TOWARDS THE RATIONAL DESIGN OF PEPTIDE DRUGS

OpenAIRE

YEŞİLADA, Akgül; ÖZKANLI, Fügen

2004-01-01

In this review, after a short introduction to definition and physiological roles of regulatory peptides, problems faced during the development of peptide drugs, studies directed to solve these problems and rational design of peptide drugs with special emphesis on peptidomimetics are mentioned

Time-Domain Ab Initio Analysis of Excitation Dynamics in a Quantum Dot/Polymer Hybrid: Atomistic Description Rationalizes Experiment.

Science.gov (United States)

Long, Run; Prezhdo, Oleg V

2015-07-08

Hybrid organic/inorganic polymer/quantum dot (QD) solar cells are an attractive alternative to the traditional cells. The original, simple models postulate that one-dimensional polymers have continuous energy levels, while zero-dimensional QDs exhibit atom-like electronic structure. A realistic, atomistic viewpoint provides an alternative description. Electronic states in polymers are molecule-like: finite in size and discrete in energy. QDs are composed of many atoms and have high, bulk-like densities of states. We employ ab initio time-domain simulation to model the experimentally observed ultrafast photoinduced dynamics in a QD/polymer hybrid and show that an atomistic description is essential for understanding the time-resolved experimental data. Both electron and hole transfers across the interface exhibit subpicosecond time scales. The interfacial processes are fast due to strong electronic donor-acceptor, as evidenced by the densities of the photoexcited states which are delocalized between the donor and the acceptor. The nonadiabatic charge-phonon coupling is also strong, especially in the polymer, resulting in rapid energy losses. The electron transfer from the polymer is notably faster than the hole transfer from the QD, due to a significantly higher density of acceptor states. The stronger molecule-like electronic and charge-phonon coupling in the polymer rationalizes why the electron-hole recombination inside the polymer is several orders of magnitude faster than in the QD. As a result, experiments exhibit multiple transfer times for the long-lived hole inside the QD, ranging from subpicoseconds to nanoseconds. In contrast, transfer of the short-lived electron inside the polymer does not occur beyond the first picosecond. The energy lost by the hole on its transit into the polymer is accommodated by polymer's high-frequency vibrations. The energy lost by the electron injected into the QD is accommodated primarily by much lower-frequency collective and

A rational approach for ω-transaminase-catalyzed process design

DEFF Research Database (Denmark)

T. Gundersen, Maria; Lloyd, Richard; Tufvesson, Pär

Herein we describe a novel rational approach to the design of a ω-transaminase process such that it will fulfill criteria necessary for industrial use. By first determining the fundamental properties of the reaction system, it is possible to suggest appropriate process strategies that may be used...

Second-Order Nonlinear Optical Dendrimers and Dendronized Hyperbranched Polymers.

Science.gov (United States)

Tang, Runli; Li, Zhen

2017-01-01

Second-order nonlinear optical (NLO) dendrimers with a special topological structure were regarded as the most promising candidates for practical applications in the field of optoelectronic materials. Dendronized hyperbranched polymers (DHPs), a new type of polymers with dendritic structures, proposed and named by us recently, demonstrated interesting properties and some advantages over other polymers. Some of our work concerning these two types of polymers are presented herein, especially focusing on the design idea and structure-property relationship. To enhance their comprehensive NLO performance, dendrimers were designed and synthesized by adjusting their isolation mode, increasing the number of the dendritic generation, modifying their topological structure, introducing isolation chromophores, and utilizing the Ar-Ar F self-assembly effect. To make full use of the advantages of both the structural integrity of dendrimers and the convenient one-pot synthesis of hyperbranched polymers, DHPs were explored by utilizing low-generation dendrons as big monomers to construct hyperbranched polymers. These selected works could provide valuable information to deeply understand the relationship between the structure and properties of functional polymers with dendritic structures, but not only limited to the NLO ones, and might contribute much to the further development of functional polymers with rational design. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intrinsic immunogenicity of rapidly-degradable polymers evolves during degradation.

Science.gov (United States)

Andorko, James I; Hess, Krystina L; Pineault, Kevin G; Jewell, Christopher M

2016-03-01

Recent studies reveal many biomaterial vaccine carriers are able to activate immunostimulatory pathways, even in the absence of other immune signals. How the changing properties of polymers during biodegradation impact this intrinsic immunogenicity is not well studied, yet this information could contribute to rational design of degradable vaccine carriers that help direct immune response. We use degradable poly(beta-amino esters) (PBAEs) to explore intrinsic immunogenicity as a function of the degree of polymer degradation and polymer form (e.g., soluble, particles). PBAE particles condensed by electrostatic interaction to mimic a common vaccine approach strongly activate dendritic cells, drive antigen presentation, and enhance T cell proliferation in the presence of antigen. Polymer molecular weight strongly influences these effects, with maximum stimulation at short degradation times--corresponding to high molecular weight--and waning levels as degradation continues. In contrast, free polymer is immunologically inert. In mice, PBAE particles increase the numbers and activation state of cells in lymph nodes. Mechanistic studies reveal that this evolving immunogenicity occurs as the physicochemical properties and concentration of particles change during polymer degradation. This work confirms the immunological profile of degradable, synthetic polymers can evolve over time and creates an opportunity to leverage this feature in new vaccines. Degradable polymers are increasingly important in vaccination, but how the inherent immunogenicity of polymers changes during degradation is poorly understood. Using common rapidly-degradable vaccine carriers, we show that the activation of immune cells--even in the absence of other adjuvants--depends on polymer form (e.g., free, particulate) and the extent of degradation. These changing characteristics alter the physicochemical properties (e.g., charge, size, molecular weight) of polymer particles, driving changes in

Design rationalization and the logic of design: a case study

DEFF Research Database (Denmark)

Galle, Per

1996-01-01

various ‘sources of credibility’ of premises, items of general background knowledge, and several (abductive and deductive) patterns of inference which suggest a possible ‘logic of design’. Rationalization of decisions is defined, and many decisions are found not to be fully rationalized, despite...... the apparent rationality of the reasoning....

Experimental Polymer Mechanochemistry and its Interpretational Frameworks.

Science.gov (United States)

Akbulatov, Sergey; Boulatov, Roman

2017-06-02

Polymer mechanochemistry is an emerging field at the interface of chemistry, materials science, physics and engineering. It aims at understanding and exploiting unique reactivities of polymer chains confined to highly non-equilibrium stretched geometries by interactions with their surroundings. Macromolecular chains or their segments become stretched in bulk polymers under mechanical loads or when polymer solutions are sonicated or flow rapidly through abrupt contractions. An increasing amount of empirical data suggests that mechanochemical phenomena are widespread wherever polymers are used. In the past decade, empirical mechanochemistry has progressed enormously, from studying fragmentations of commodity polymers by simple backbone homolysis to demonstrations of self-strengthening and stress-reporting materials and mechanochemical cascades using purposefully designed monomers. This progress has not yet been matched by the development of conceptual frameworks within which to rationalize, systematize and generalize empirical mechanochemical observations. As a result, mechanistic and/or quantitative understanding of mechanochemical phenomena remains, with few exceptions, tentative. In this review we aim at systematizing reported macroscopic manifestations of polymer mechanochemistry, and critically assessing the interpretational framework that underlies their molecular rationalizations from a physical chemist's perspective. We propose a hierarchy of mechanochemical phenomena which may guide the development of multiscale models of mechanochemical reactivity to match the breadth and utility of the Eyring equation of chemical kinetics. We discuss the limitations of the approaches to quantifying and validating mechanochemical reactivity, with particular focus on sonicated polymer solutions, in order to identify outstanding questions that need to be solved for polymer mechanochemistry to become a rigorous, quantitative field. We conclude by proposing 7 problems whose

Rational Design of Cancer-Targeted Benzoselenadiazole by RGD Peptide Functionalization for Cancer Theranostics.

Science.gov (United States)

Yang, Liye; Li, Wenying; Huang, Yanyu; Zhou, Yangliang; Chen, Tianfeng

2015-09-01

A cancer-targeted conjugate of the selenadiazole derivative BSeC (benzo[1,2,5] selenadiazole-5-carboxylic acid) with RGD peptide as targeting molecule and PEI (polyethylenimine) as a linker is rationally designed and synthesized in the present study. The results show that RGD-PEI-BSeC forms nanoparticles in aqueous solution with a core-shell nanostructure and high stability under physiological conditions. This rational design effectively enhances the selective cellular uptake and cellular retention of BSeC in human glioma cells, and increases its selectivity between cancer and normal cells. The nanoparticles enter the cells through receptor-mediated endocytosis via clathrin-mediated and nystatin-dependent lipid raft-mediated pathways. Internalized nanoparticles trigger glioma cell apoptosis by activation of ROS-mediated p53 phosphorylation. Therefore, this study provides a strategy for the rational design of selenium-containing cancer-targeted theranostics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A tailored biocatalyst achieved by the rational anchoring of imidazole groups on a natural polymer: furnishing a potential artificial nuclease by sustainable materials engineering.

Science.gov (United States)

Ferreira, José G L; Grein-Iankovski, Aline; Oliveira, Marco A S; Simas-Tosin, Fernanda F; Riegel-Vidotti, Izabel C; Orth, Elisa S

2015-04-11

Foreseeing the development of artificial enzymes by sustainable materials engineering, we rationally anchored reactive imidazole groups on gum arabic, a natural biocompatible polymer. The tailored biocatalyst GAIMZ demonstrated catalytic activity (>10(5)-fold) in dephosphorylation reactions with recyclable features and was effective in cleaving plasmid DNA, comprising a potential artificial nuclease.

Highly efficient polymer solar cells with printed photoactive layer: rational process transfer from spin-coating

KAUST Repository

Zhao, Kui

2016-09-05

Scalable and continuous roll-to-roll manufacturing is at the heart of the promise of low-cost and high throughput manufacturing of solution-processed photovoltaics. Yet, to date the vast majority of champion organic solar cells reported in the literature rely on spin-coating of the photoactive bulk heterojunction (BHJ) layer, with the performance of printed solar cells lagging behind in most instances. Here, we investigate the performance gap between polymer solar cells prepared by spin-coating and blade-coating the BHJ layer for the important class of modern polymers exhibiting no long range crystalline order. We find that thickness parity does not always yield performance parity even when using identical formulations. Significant differences in the drying kinetics between the processes are found to be responsible for BHJ nanomorphology differences. We propose an approach which benchmarks the film drying kinetics and associated BHJ nanomorphology development against those of the champion laboratory devices prepared by spin-coating the BHJ layer by adjusting the process temperature. If the optimization requires the solution concentration to be changed, then it is crucial to maintain the additive-to-solute volume ratio. Emulating the drying kinetics of spin-coating is also shown to help achieve morphological and performance parities. We put this approach to the test and demonstrate printed PTB7:PC71BM polymer solar cells with efficiency of 9% and 6.5% PCEs on glass and flexible PET substrates, respectively. We further demonstrate performance parity for two other popular donor polymer systems exhibiting rigid backbones and absence of a long range crystalline order, achieving a PCE of 9.7%, the highest efficiency reported to date for a blade coated organic solar cell. The rational process transfer illustrated in this study should help the broader and successful adoption of scalable printing methods for these material systems.

Structure-based, rational design of T cell receptors

Directory of Open Access Journals (Sweden)

Vincent eZoete

2013-09-01

Full Text Available Adoptive cell transfer using engineered T cells is emerging as a promising treatment for metastatic melanoma. Such an approach allows one to introduce TCR modifications that, while maintaining the specificity for the targeted antigen, can enhance the binding and kinetic parameters for the interaction pMHC. Using the well-characterized 2C TCR/SIYR/H-2K(b structure as a model system, we demonstrated that a binding free energy decomposition based on the MM-GBSA approach provides a detailed and reliable description of the TCR/pMHC interactions at the structural and thermodynamic levels. Starting from this result, we developed a new structure-based approach, to rationally design new TCR sequences, and applied it to the BC1 TCR targeting the HLA-A2 restricted NY-ESO-1157-165 cancer-testis epitope. 54% of the designed sequence replacements exhibited improved pMHC-binding as compared to the native TCR, with up to 150 fold increase in affinity, while preserving specificity. Genetically-engineered CD8+ T cells expressing these modified TCRs showed an improved functional activity compared to those expressing BC1 TCR. We measured maximum levels of activities for TCRs within the upper limit of natural affinity. Beyond the affinity threshold at KD < 1 μM we observed an attenuation in cellular function. We have also developed a homology modeling-based approach, TCRep 3D, to obtain accurate structural models of any TCR-pMHC complexes. We have complemented the approach with a simplified rigid method to predict the TCR orientation over pMHC. These methods potentially extend the use of our TCR engineering method to entire TCR repertoires for which no X-ray structure is available. We have also performed a steered molecular dynamics study of the unbinding of the TCR-pMHC complex to get a better understanding of how TCRs interact with pMHCs. This entire rational TCR design pipeline is now being used to produce rationally optimized TCRs for adoptive cell therapies of

Consequences of chirality on the dynamics of a water-soluble supramolecular polymer.

Science.gov (United States)

Baker, Matthew B; Albertazzi, Lorenzo; Voets, Ilja K; Leenders, Christianus M A; Palmans, Anja R A; Pavan, Giovanni M; Meijer, E W

2015-02-20

The rational design of supramolecular polymers in water is imperative for their widespread use, but the design principles for these systems are not well understood. Herein, we employ a multi-scale (spatial and temporal) approach to differentiate two analogous water-soluble supramolecular polymers: one with and one without a stereogenic methyl. Initially aiming simply to understand the molecular behaviour of these systems in water, we find that while the fibres may look identical, the introduction of homochirality imparts a higher level of internal order to the supramolecular polymer. Although this increased order does not seem to affect the basic dimensions of the supramolecular fibres, the equilibrium dynamics of the polymers differ by almost an order of magnitude. This report represents the first observation of a structure/property relationship with regard to equilibrium dynamics in water-soluble supramolecular polymers.

Consequences of chirality on the dynamics of a water-soluble supramolecular polymer

Science.gov (United States)

Baker, Matthew B.; Albertazzi, Lorenzo; Voets, Ilja K.; Leenders, Christianus M. A.; Palmans, Anja R. A.; Pavan, Giovanni M.; Meijer, E. W.

2015-02-01

The rational design of supramolecular polymers in water is imperative for their widespread use, but the design principles for these systems are not well understood. Herein, we employ a multi-scale (spatial and temporal) approach to differentiate two analogous water-soluble supramolecular polymers: one with and one without a stereogenic methyl. Initially aiming simply to understand the molecular behaviour of these systems in water, we find that while the fibres may look identical, the introduction of homochirality imparts a higher level of internal order to the supramolecular polymer. Although this increased order does not seem to affect the basic dimensions of the supramolecular fibres, the equilibrium dynamics of the polymers differ by almost an order of magnitude. This report represents the first observation of a structure/property relationship with regard to equilibrium dynamics in water-soluble supramolecular polymers.

Rationalization of design and construction of buildings for nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Satoh, Shunsaku; Mitsumatsu, Kazuo

1987-02-01

This article presents various rationalization methods introduced in the past few years for design and construction of BWR nuclear power plant buildings. When the site for a nuclear power plant has been decided, investigation is made on various aspects of possible earthquakes, based on which anti-earthquake design for the plant site is established. The next step is to examine the displacements and stresses that may occur to various parts of the bulding from a postulated earthquake. This is normally called the earthquake response analysis and consists of calculating the behaviors of the buildings using large computers. A seismic controlled structure system has recently proposed, aiming to reduce the displacements and stresses of the building itself by controlling the flexibility of the installed seismic apparatus against the input of external loads. Lately, high strength concrete and high strength reinforcing steel bars (rebars) are being considered for practical application. If advanced computers and related accessories are utilized to the maximum, it will lead not only to efficiency in the design work but to the possibility of optimized design. For rational construction, a combined scaffolding and temporary support has been devised to reduce the time and volume of required temporary work. What have been developed for rationalization of construction work also include robots for heavy weight rebar fabrication, horizontal reed blind type rebars, portable concrete distributor, all weather environment facilities, and construction materials conveyance system. (Nogami, K.).

Rationalization of design and construction of buildings for nuclear power plants

International Nuclear Information System (INIS)

Satoh, Shunsaku; Mitsumatsu, Kazuo

1987-01-01

This article presents various rationalization methods introduced in the past few years for design and construction of BWR nuclear power plant buildings. When the site for a nuclear power plant has been decided, investigation is made on various aspects of possible earthquakes, based on which anti-earthquake design for the plant site is established. The next step is to examine the displacements and stresses that may occur to various parts of the bulding from a postulated earthquake. This is normally called the earthquake response analysis and consists of calculating the behaviors of the buildings using large computers. A seismic controlled structure system has recently proposed, aiming to reduce the displacements and stresses of the building itself by controlling the flexibility of the installed seismic apparatus against the input of external loads. Lately, high strength concrete and high strength reinforcing steel bars (rebars) are being considered for practical application. If advanced computers and related accessories are utilized to the maximum, it will lead not only to efficiency in the design work but to the possibility of optimized design. For rational construction, a combined scaffolding and temporary support has been devised to reduce the time and volume of required temporary work. What have been developed for rationalization of construction work also include robots for heavy weight rebar fabrication, horizontal reed blind type rebars, portable concrete distributor, all weather environment facilities, and construction materials conveyance system. (Nogami, K.)

On rationally supported surfaces

DEFF Research Database (Denmark)

Gravesen, Jens; Juttler, B.; Sir, Z.

2008-01-01

We analyze the class of surfaces which are equipped with rational support functions. Any rational support function can be decomposed into a symmetric (even) and an antisymmetric (odd) part. We analyze certain geometric properties of surfaces with odd and even rational support functions....... In particular it is shown that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors, which were discussed by Sampoli et al. (Sampoli, M.L., Peternell, M., Juttler, B., 2006. Rational surfaces with linear normals and their convolutions...... with rational surfaces. Comput. Aided Geom. Design 23, 179-192). As shown recently, this class of surfaces includes non-developable quadratic triangular Bezier surface patches (Lavicka, M., Bastl, B., 2007. Rational hypersurfaces with rational convolutions. Comput. Aided Geom. Design 24, 410426; Peternell, M...

Rational assembly of nanoparticle superlattices with designed lattice symmetries

Science.gov (United States)

Gang, Oleg; Lu, Fang; Tagawa, Miho

2017-09-05

A method for lattice design via multivalent linkers (LDML) is disclosed that introduces a rationally designed symmetry of connections between particles in order to achieve control over the morphology of their assembly. The method affords the inclusion of different programmable interactions within one linker that allow an assembly of different types of particles. The designed symmetry of connections is preferably provided utilizing DNA encoding. The linkers may include fabricated "patchy" particles, DNA scaffold constructs and Y-shaped DNA linkers, anisotropic particles, which are preferably functionalized with DNA, multimeric protein-DNA complexes, and particles with finite numbers of DNA linkers.

Rational design of soft mechanical metamaterials : Independent tailoring of elastic properties with randomness

NARCIS (Netherlands)

Mirzaali Mazandarani, M.J.; Hedayati, R.; Vena, P; Vergani, L.; Strano, M.; Zadpoor, A.A.

2017-01-01

The elastic properties of mechanical metamaterials are direct functions of their topological designs. Rational design approaches based on computational models could, therefore, be used to devise topological designs that result in the desired properties. It is of particular importance to

Molecular Design and Functional Control of Novel Self-Oscillating Polymers

Directory of Open Access Journals (Sweden)

Ryo Yoshida

2010-02-01

Full Text Available If we could realize an autonomous polymer system driven under biological conditions by a tailor-made molecular design, human beings could create unprecedented biomimetic functions and materials such as heartbeats, autonomous peristaltic pumps, etc. In order to achieve this objective, we have investigated the molecular design of such a polymer system. As a result, we were the first to demonstrate a self-oscillating polymer system driven in a solution where only malonic acid existed, which could convert the chemical energy of the Belousov-Zhabotinsky (BZ reaction into a change in the conformation of the polymer chain. To cause the self-oscillation in solution, we have attempted to construct a built-in system where the required BZ system substrates other than the organic acid are incorporated into the polymer itself. That is, the novel polymer chain incorporated the metal catalyst of the BZ reaction, a pH-control site and an oxidant supply site at the same time. As a result of introducing the pH control and oxidant supply sites into the conventional-type self-oscillating polymer chain, the novel polymer chain caused aggregation-disaggregation self-oscillations in the solution. We clarified that the period of the self-oscillation of the novel self-oscillating polymer chain was proportional to the concentration of the malonic acid. Therefore, the concentration of the malonic acid can be determined by measuring the period of the novel self-oscillating polymer solution. In this review, we introduce the detailed molecular design of the novel self-oscillating polymer chain and its self-oscillating behavior. Moreover, we report an autonomous self-oscillating polymer gel actuator that causes a bending-stretching motion under the constant conditions.

Natural Gas Purification Using a Porous Coordination Polymer with Water and Chemical Stability

NARCIS (Netherlands)

Duan, J.; Jin, W.; Krishna, R.

2015-01-01

Porous coordination polymers (PCPs), constructed by bridging the metals or clusters and organic linkers, can provide a functional pore environment for gas storage and separation. But the rational design for identifying PCPs with high efficiency and low energy cost remains a challenge. Here, we

Development of the computer-aided process planning (CAPP system for polymer injection molds manufacturing

Directory of Open Access Journals (Sweden)

J. Tepić

2011-10-01

Full Text Available Beginning of production and selling of polymer products largely depends on mold manufacturing. The costs of mold manufacturing have significant share in the final price of a product. The best way to improve and rationalize polymer injection molds production process is by doing mold design automation and manufacturing process planning automation. This paper reviews development of a dedicated process planning system for manufacturing of the mold for injection molding, which integrates computer-aided design (CAD, computer-aided process planning (CAPP and computer-aided manufacturing (CAM technologies.

Theoretical studies of optics and charge transport in organic conducting oligomers and polymers: Rational design of improved transparent and conducting polymers

Science.gov (United States)

Hutchison, Geoffrey Rogers

Theoretical studies on a variety of oligo- and polyheterocycles elucidate their optical and charge transport properties, suggesting new, improved transparent conductive polymers. First-principles calculations provide accurate methodologies for predicting both optical band gaps of neutral and cationic oligomers and intrinsic charge transfer rates. Multidimensional analysis reveals important motifs in chemical tailorability of oligoheterocycle optical and charge transport properties. The results suggest new directions for design of novel materials. Using both finite oligomer and infinite polymer calculations, the optical band gaps in polyheterocycles follow a modified particle-in-a-box formalism, scaling approximately as 1/N (where N is the number of monomer units) in short chains, saturating for long chains. Calculations demonstrate that band structure changes upon heteroatom substitution, (e.g., from polythiophene to polypyrrole) derive from heteroatom electron affinity. Further investigation of chemical variability in substituted oligoheterocycles using multidimensional statistics reveals the interplay between heteroatom and substituent in correlations between structure and redox/optical properties of neutral and cationic species. A linear correlation between band gaps of neutral and cationic species upon oxidation of conjugated oligomers, shows redshifts of optical absorption for most species and blueshifts for small band gap species. Interstrand charge-transport studies focus on two contributors to hopping-style charge transfer rates: internal reorganization energy and the electronic coupling matrix element. Statistical analysis of chemical variability of reorganization energies in oligoheterocycles proves the importance of reorganization energy in determining intrinsic charge transfer rates (e.g., charge mobility in unsubstituted oligothiophenes). Computed bandwidths across several oligothiophene crystal packing motifs show similar electron and hole bandwidths

Unravelling ``off-target'' effects of redox-active polymers and polymer multilayered capsules in prostate cancer cells

Science.gov (United States)

Beretta, Giovanni L.; Folini, Marco; Cavalieri, Francesca; Yan, Yan; Fresch, Enrico; Kaliappan, Subramanian; Hasenöhrl, Christoph; Richardson, Joseph J.; Tinelli, Stella; Fery, Andreas; Caruso, Frank; Zaffaroni, Nadia

2015-03-01

Redox-active polymers and carriers are oxidizing nanoagents that can potentially trigger intracellular off-target effects. In the present study, we investigated the occurrence of off-target effects in prostate cancer cells following exposure to redox-active polymer and thin multilayer capsules with different chemical properties. We show that, depending on the intracellular antioxidant capacity, thiol-functionalized poly(methacrylic acid), PMASH triggers cell defense responses/perturbations that result in off-target effects (i.e., induction of autophagy and down-regulation of survivin). Importantly, the conversion of the carboxyl groups of PMASH into the neutral amides of poly(hydroxypropylmetacrylamide) (pHPMASH) nullified the off-target effects and cytotoxicity in tested cell lines. This suggests that the simultaneous action of carboxyl and disulfide groups in PMASH polymer or capsules may play a role in mediating the intracellular off-target effects. Our work provides evidence that the rational design of redox-active carriers for therapeutic-related application should be guided by a careful investigation on potential disturbance of the cellular machineries related to the carrier association.Redox-active polymers and carriers are oxidizing nanoagents that can potentially trigger intracellular off-target effects. In the present study, we investigated the occurrence of off-target effects in prostate cancer cells following exposure to redox-active polymer and thin multilayer capsules with different chemical properties. We show that, depending on the intracellular antioxidant capacity, thiol-functionalized poly(methacrylic acid), PMASH triggers cell defense responses/perturbations that result in off-target effects (i.e., induction of autophagy and down-regulation of survivin). Importantly, the conversion of the carboxyl groups of PMASH into the neutral amides of poly(hydroxypropylmetacrylamide) (pHPMASH) nullified the off-target effects and cytotoxicity in tested cell

Does decision documentation help junior designers rationalize their decisions? A comparative multiple-case study

NARCIS (Netherlands)

Heesch, U. van; Avgeriou, P.; Tang, A.

Software architecture design is challenging, especially for junior software designers. Lacking practice and experience, junior designers need process support in order to make rational architecture decisions. In this paper, we present the results of a comparative multiple-case study conducted to find

Functional polymers as therapeutic agents: concept to market place.

Science.gov (United States)

Dhal, Pradeep K; Polomoscanik, Steven C; Avila, Louis Z; Holmes-Farley, S Randall; Miller, Robert J

2009-11-12

Biologically active synthetic polymers have received considerable scientific interest and attention in recent years for their potential as promising novel therapeutic agents to treat human diseases. Although a significant amount of research has been carried out involving polymer-linked drugs as targeted and sustained release drug delivery systems and prodrugs, examples on bioactive polymers that exhibit intrinsic therapeutic properties are relatively less. Several appealing characteristics of synthetic polymers including high molecular weight, molecular architecture, and controlled polydispersity can all be utilized to discover a new generation of therapies. For example, high molecular weight bioactive polymers can be restricted to gastrointestinal tract, where they can selectively recognize, bind, and remove target disease causing substances from the body. The appealing features of GI tract restriction and stability in biological environment render these polymeric drugs to be devoid of systemic toxicity that are generally associated with small molecule systemic drugs. The present article highlights recent developments in the rational design and synthesis of appropriate functional polymers that have resulted in a number of promising polymer based therapies and biomaterials, including some marketed products.

Fundamental understanding and rational design of high energy structural microbatteries

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuxing; Li, Qiuyan; Cartmell, Samuel; Li, Huidong; Mendoza, Sarah; Zhang, Ji-Guang; Deng, Zhiqun Daniel; Xiao, Jie

2018-01-01

Microbatteries play a critical role in determining the lifetime of downsized sensors, wearable devices and medical applications, etc. More often, structural batteries are required from the perspective of aesthetics and space utilization, which is however rarely explored. Herein, we discuss the fundamental issues associated with the rational design of practically usable high energy microbatteries. The tubular shape of the cell further allows the flexible integration of microelectronics. A functioning acoustic micro-transmitter continuously powered by this tubular battery has been successfully demonstrated. Multiple design features adopted to accommodate large mechanical stress during the rolling process are discussed providing new insights in designing the structural microbatteries for emerging technologies.

Peptides Displayed as High Density Brush Polymers Resist Proteolysis and Retain Bioactivity

Science.gov (United States)

2015-01-01

We describe a strategy for rendering peptides resistant to proteolysis by formulating them as high-density brush polymers. The utility of this approach is demonstrated by polymerizing well-established cell-penetrating peptides (CPPs) and showing that the resulting polymers are not only resistant to proteolysis but also maintain their ability to enter cells. The scope of this design concept is explored by studying the proteolytic resistance of brush polymers composed of peptides that are substrates for either thrombin or a metalloprotease. Finally, we demonstrate that the proteolytic susceptibility of peptide brush polymers can be tuned by adjusting the density of the polymer brush and offer in silico models to rationalize this finding. We contend that this strategy offers a plausible method of preparing peptides for in vivo use, where rapid digestion by proteases has traditionally restricted their utility. PMID:25314576

Random polyfluorene co -polymers designed for a better optical ...

African Journals Online (AJOL)

Two alternating polyfluorenes (APFO15-F8BT and APFO3-F8BT) with full absorption of the visible region of the electromagnetic radiation were designed and synthesized for bulk-heterojunction solar cell devices. The optical and electrochemical properties of the two polymers were studied. The two polymers exhibited strong ...

Supramolecular Architectures and Mimics of Complex Natural Folds Derived from Rationally Designed alpha-Helical Protein Structures

Science.gov (United States)

Tavenor, Nathan Albert

Protein-based supramolecular polymers (SMPs) are a class of biomaterials which draw inspiration from and expand upon the many examples of complex protein quaternary structures observed in nature: collagen, microtubules, viral capsids, etc. Designing synthetic supramolecular protein scaffolds both increases our understanding of natural superstructures and allows for the creation of novel materials. Similar to small-molecule SMPs, protein-based SMPs form due to self-assembly driven by intermolecular interactions between monomers, and monomer structure determines the properties of the overall material. Using protein-based monomers takes advantage of the self-assembly and highly specific molecular recognition properties encodable in polypeptide sequences to rationally design SMP architectures. The central hypothesis underlying our work is that alpha-helical coiled coils, a well-studied protein quaternary folding motif, are well-suited to SMP design through the addition of synthetic linkers at solvent-exposed sites. Through small changes in the structures of the cross-links and/or peptide sequence, we have been able to control both the nanoscale organization and the macroscopic properties of the SMPs. Changes to the linker and hydrophobic core of the peptide can be used to control polymer rigidity, stability, and dimensionality. The gaps in knowledge that this thesis sought to fill on this project were 1) the relationship between the molecular structure of the cross-linked polypeptides and the macroscopic properties of the SMPs and 2) a means of creating materials exhibiting multi-dimensional net or framework topologies. Separate from the above efforts on supramolecular architectures was work on improving backbone modification strategies for an alpha-helix in the context of a complex protein tertiary fold. Earlier work in our lab had successfully incorporated unnatural building blocks into every major secondary structure (beta-sheet, alpha-helix, loops and beta

Rational Multiparty Computation

OpenAIRE

Wallrabenstein, John Ross

2014-01-01

The field of rational cryptography considers the design of cryptographic protocols in the presence of rational agents seeking to maximize local utility functions. This departs from the standard secure multiparty computation setting, where players are assumed to be either honest or malicious. ^ We detail the construction of both a two-party and a multiparty game theoretic framework for constructing rational cryptographic protocols. Our framework specifies the utility function assumptions neces...

Designing institutions for climate change: Why rational design involves technology

Energy Technology Data Exchange (ETDEWEB)

Coninck, H. de [Energy Research Centre of the Netherlands, Petten (Netherlands)

2008-09-30

This paper aims to explore how to augment the institutional solutions offered by current political theory for addressing the unprecedented problem of climate change. Although steering directly at emission reductions in an international treaty has benefits in terms of cost-effectiveness, the paper arrives at the conclusion that considerations around technological development should be drawn into the treaty equation in order to generate sufficient reciprocity to have a politically feasible international regime. It then argues that the benefits of technology agreements for climate change mitigation may be larger than commonly assumed, as they - if properly designed - could lead to real emission reductions and provide more flexibility to reach agreement in post-2012 negotiations than proposals modelled exclusively on the Kyoto Protocol or other types of absolute emission targets. Based on rational design of international institutions for environmental governance, and attempting to take into account considerations of technological dynamics and the 'sociotechnical system', contours of a possible environmentally effective and politically feasible international climate change agreements are sketched.

Fundamental understanding and rational design of high energy structural microbatteries

International Nuclear Information System (INIS)

Wang, Yuxing; Li, Qiuyan; Cartmell, Samuel; Li, Huidong; Mendoza, Sarah

2017-01-01

We present that microbatteries play a critical role in determining the lifetime of downsized sensors, wearable devices, medical applications, and animal acoustic telemetry transmitters among others. More often, structural batteries are required from the perspective of aesthetics and space utilization, which is however rarely explored. Herein, we discuss the fundamental issues associated with the rational design of practically usable high energy microbatteries. The tubular shape of the cell further allows the flexible integration of microelectronics. A functioning acoustic micro-transmitter continuously powered by this tubular battery has been successfully demonstrated. Finally, multiple design features adopted to accommodate large mechanical stress during the rolling process are discussed providing new insights in designing the structural microbatteries for emerging technologies.

Multi-Step Usage of in Vivo Models During Rational Drug Design and Discovery

Directory of Open Access Journals (Sweden)

Charles H. Williams

2011-04-01

Full Text Available In this article we propose a systematic development method for rational drug design while reviewing paradigms in industry, emerging techniques and technologies in the field. Although the process of drug development today has been accelerated by emergence of computational methodologies, it is a herculean challenge requiring exorbitant resources; and often fails to yield clinically viable results. The current paradigm of target based drug design is often misguided and tends to yield compounds that have poor absorption, distribution, metabolism, and excretion, toxicology (ADMET properties. Therefore, an in vivo organism based approach allowing for a multidisciplinary inquiry into potent and selective molecules is an excellent place to begin rational drug design. We will review how organisms like the zebrafish and Caenorhabditis elegans can not only be starting points, but can be used at various steps of the drug development process from target identification to pre-clinical trial models. This systems biology based approach paired with the power of computational biology; genetics and developmental biology provide a methodological framework to avoid the pitfalls of traditional target based drug design.

Rational Design of Semiconductor Nanostructures for Functional Subcellular Interfaces.

Science.gov (United States)

Parameswaran, Ramya; Tian, Bozhi

2018-05-15

One of the fundamental questions guiding research in the biological sciences is how cellular systems process complex physical and environmental cues and communicate with each other across multiple length scales. Importantly, aberrant signal processing in these systems can lead to diseases that can have devastating impacts on human lives. Biophysical studies in the past several decades have demonstrated that cells can respond to not only biochemical cues but also mechanical and electrical ones. Thus, the development of new materials that can both sense and modulate all of these pathways is necessary. Semiconducting nanostructures are an emerging class of discovery platforms and tools that can push the limits of our ability to modulate and sense biological behaviors for both fundamental research and clinical applications. These materials are of particular interest for interfacing with cellular systems due to their matched dimension with subcellular components (e.g., cytoskeletal filaments), and easily tunable properties in the electrical, optical and mechanical regimes. Rational design via traditional or new approaches, such as nanocasting and mesoscale chemical lithography, can allow us to control micro- and nanoscale features in nanowires to achieve new biointerfaces. Both processes endogenous to the target cell and properties of the material surface dictate the character of these interfaces. In this Account, we focus on (1) approaches for the rational design of semiconducting nanowires that exhibit unique structures for biointerfaces, (2) recent fundamental discoveries that yield robust biointerfaces at the subcellular level, (3) intracellular electrical and mechanical sensing, and (4) modulation of cellular behaviors through material topography and remote physical stimuli. In the first section, we discuss new approaches for the synthetic control of micro- and nanoscale features of these materials. In the second section, we focus on achieving biointerfaces with

Rational design for enhancing inflammation-responsive in vivo chemiluminescence via nanophotonic energy relay to near-infrared AIE-active conjugated polymer.

Science.gov (United States)

Seo, Young Hun; Singh, Ajay; Cho, Hong-Jun; Kim, Youngsun; Heo, Jeongyun; Lim, Chang-Keun; Park, Soo Young; Jang, Woo-Dong; Kim, Sehoon

2016-04-01

H2O2-specific peroxalate chemiluminescence is recognized as a potential signal for sensitive in vivo imaging of inflammation but the effect of underlying peroxalate-emitter energetics on its efficiency has rarely been understood. Here we report a simple nanophotonic way of boosting near-infrared chemiluminescence with no need of complicated structural design and synthesis of an energetically favored emitter. The signal enhancement was attained from the construction of a nanoparticle imaging probe (∼26 nm in size) by dense nanointegration of multiple molecules possessing unique photonic features, i.e., i) a peroxalate as a chemical fuel generating electronic excitation energy in response to inflammatory H2O2, ii) a low-bandgap conjugated polymer as a bright near-infrared emitter showing aggregation-induced emission (AIE), and iii) an energy gap-bridging photonic molecule that relays the chemically generated excitation energy to the emitter for its efficient excitation. From static and kinetic spectroscopic studies, a green-emissive BODIPY dye has proven to be an efficient relay molecule to bridge the energy gap between the AIE polymer and the chemically generated excited intermediate of H2O2-reacted peroxalates. The energy-relayed nanointegration of AIE polymer and peroxalate in water showed a 50-times boosted sensing signal compared to their dissolved mixture in THF. Besides the high H2O2 detectability down to 10(-9) M, the boosted chemiluminescence presented a fairly high tissue penetration depth (>12 mm) in an ex vivo condition, which enabled deep imaging of inflammatory H2O2 in a hair-covered mouse model of peritonitis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rational design and application of responsive α-helical peptide hydrogels

Science.gov (United States)

Banwell, Eleanor F.; Abelardo, Edgardo S.; Adams, Dave J.; Birchall, Martin A.; Corrigan, Adam; Donald, Athene M.; Kirkland, Mark; Serpell, Louise C.; Butler, Michael F.; Woolfson, Derek N.

2009-01-01

Biocompatible hydrogels have a wide variety of potential applications in biotechnology and medicine, such as the controlled delivery and release of cells, cosmetics and drugs; and as supports for cell growth and tissue engineering1. Rational peptide design and engineering are emerging as promising new routes to such functional biomaterials2-4. Here we present the first examples of rationally designed and fully characterized self-assembling hydrogels based on standard linear peptides with purely α-helical structures, which we call hydrogelating self-assembling fibres (hSAFs). These form spanning networks of α-helical fibrils that interact to give self-supporting physical hydrogels of >99% water content. The peptide sequences can be engineered to alter the underlying mechanism of gelation and, consequently, the hydrogel properties. Interestingly, for example, those with hydrogen-bonded networks melt upon heating, whereas those formed via hydrophobic interactions strengthen when warmed. The hSAFs are dual-peptide systems that only gel on mixing, which gives tight control over assembly5. These properties raise possibilities for using the hSAFs as substrates in cell culture. We have tested this in comparison with the widely used Matrigel substrate, and demonstrate that, like Matrigel, hSAFs support both growth and differentiation of rat adrenal pheochromocytoma cells for sustained periods in culture. PMID:19543314

Geology and Design: Formal and Rational Connections

Science.gov (United States)

Eriksson, S. C.; Brewer, J.

2016-12-01

Geological forms and the manmade environment have always been inextricably linked. From the time that Upper Paleolithic man created drawings in the Lascaux Caves in the southwest of France, geology has provided a critical and dramatic spoil for human creativity. This inspiration has manifested itself in many different ways, and the history of architecture is rife with examples of geologically derived buildings. During the early 20th Century, German Expressionist art and architecture was heavily influenced by the natural and often translucent quality of minerals. Architects like Bruno Taut drew and built crystalline forms that would go on to inspire the more restrained Bauhaus movement. Even within the context of Contemporary architecture, geology has been a fertile source for inspiration. Architectural practices across the globe leverage the rationality and grounding found in geology to inform a process that is otherwise dominated by computer-driven parametric design. The connection between advanced design technology and the beautifully realized geo natural forms insures that geology will be a relevant source of architectural inspiration well into the 21st century. The sometimes hidden relationship of geology to the various sub-disciplines of Design such as Architecture, Interiors, Landscape Architecture, and Historic Preservation is explored in relation to curriculum and the practice of design. Topics such as materials, form, history, the cultural and physical landscape, natural hazards, and global design enrich and inform curriculum across the college. Commonly, these help define place-based education.

Structured morphological modeling as a framework for rational strain design of Streptomyces species

NARCIS (Netherlands)

Celler, K.; Picioreanu, C.; Van Loosdrecht, M.C.M.; Van Wezel, G.P.

2012-01-01

Successful application of a computational model for rational design of industrial Streptomyces exploitation requires a better understanding of the relationship between morphology—dictated by microbial growth, branching, fragmentation and adhesion—and product formation. Here we review the

Nucleic acids for the rational design of reaction circuits.

Science.gov (United States)

Padirac, Adrien; Fujii, Teruo; Rondelez, Yannick

2013-08-01

Nucleic acid-based circuits are rationally designed in vitro assemblies that can perform complex preencoded programs. They can be used to mimic in silico computations. Recent works emphasized the modularity and robustness of these circuits, which allow their scaling-up. Another new development has led to dynamic, time-responsive systems that can display emergent behaviors like oscillations. These are closely related to biological architectures and provide an in vitro model of in vivo information processing. Nucleic acid circuits have already been used to handle various processes for technological or biotechnological purposes. Future applications of these chemical smart systems will benefit from the rapidly growing ability to design, construct, and model nucleic acid circuits of increasing size. Copyright © 2012 Elsevier Ltd. All rights reserved.

Design of molecular imprinted polymers compatible with aqueous environment.

Science.gov (United States)

Piletska, Elena V; Guerreiro, Antonio R; Romero-Guerra, Maria; Chianella, Iva; Turner, Anthony P F; Piletsky, Sergey A

2008-01-21

The main problem of poor water compatibility of molecularly imprinted polymers (MIPs) was addressed in examples describing design of synthetic receptors with high affinity for drugs of abuse. An extensive potentiometric titration of 10 popular functional monomers and corresponding imprinted and blank polymers was conducted in order to evaluate the subtleties of functional groups ionisation under aqueous conditions. It was found that polymers prepared using 2-trifluoromethacrylic acid (TFMAA) in combination with toluene as porogen possess superior properties which make them suitable for effective template recognition in water. The potential impact of phase separation during polymerisation on formation of high quality imprints has been discussed. Three drugs of abuse such as cocaine, deoxyephedrine and methadone were used as template models in polymer preparation for the practical validation of obtained results. The polymer testing showed that synthesized molecularly imprinted polymers have high affinity and selectivity for corresponding templates in aqueous environment, with imprinting factors of 2.6 for cocaine and 1.4 for methadone and deoxyephedrine. Corresponding blank polymers were unable to differentiate between analytes, suggesting that imprinting phenomenon was responsible for the recognition properties.

Computational Design of Molecularly Imprinted Polymers

Science.gov (United States)

Subrahmanyam, Sreenath; Piletsky, Sergey A.

Artificial receptors have been in use for several decades as sensor elements, in affinity separation, and as models for investigation of molecular recognition. Although there have been numerous publications on the use of molecular modeling in characterization of their affinity and selectivity, very few attempts have been made on the application of molecular modeling in computational design of synthetic receptors. This chapter discusses recent successes in the use of computational design for the development of one particular branch of synthetic receptors - molecularly imprinted polymers.

Rational use of water in trickle irrigation design.

Science.gov (United States)

Saad, J. C. C.; da Silva Junior, H. M.

2012-04-01

In trickle irrigation systems, the design is based on the pre-established emission uniformity (EU) which is the combined result of the equipment characteristics and its hydraulic configuration. However, this desired value of the EU may not be confirmed by the final project (in field conditions) and neither by the yield uniformity. However, the most important is to assure yield uniformity with rational use of water. The hypotheses of this research were: a) the EU of a trickle irrigation system at field conditions is equal to the emission uniformity pre-established in the design; b) EU has always the lowest value when compared with other indicators of uniformity; c) the discharge variation coefficient is not equal to production variation coefficient in the operational unit; d) the productivity variation coefficient is more dependent on water depth applied than the EU. This study aimed to evaluate the relationships among EU used in the irrigation system design, water depth applied and the final yield uniformity. The uniformity indicators evaluated were: EU, distribution uniformity (UD) and the index proposed by Barragan & Wu (2005). They were compared estimating the performance of a trickle irrigation system applied in a citrus orchard with dimensions of 400m x 600m. The design of the irrigation system was optimized by a Linear Programming model. The tree rows were leveled in the larger direction and the spacing adopted in the orchard was 7m x 4m. The manifold line was always operating on a slope condition. The sensitivity analysis involved different slopes, 0, 3, 6, 9 and 12%, and different values of emission uniformity, 60, 70, 75, 80, 85, 90 and 94%. The citrus yield uniformity was evaluated by the variation coefficient. The emission uniformity (EU) after design differed from the EU pre-established, more sharply in the initial values lower than 90%. Comparing the uniformity indexes, the EU always generated lower values when compared with the UD and with the index

Rational drug design paradigms: the odyssey for designing better drugs.

Science.gov (United States)

Kellici, Tahsin; Ntountaniotis, Dimitrios; Vrontaki, Eleni; Liapakis, George; Moutevelis-Minakakis, Panagiota; Kokotos, George; Hadjikakou, Sotiris; Tzakos, Andreas G; Afantitis, Antreas; Melagraki, Georgia; Bryant, Sharon; Langer, Thierry; Di Marzo, Vincenzo; Mavromoustakos, Thomas

2015-01-01

Due to the time and effort requirements for the development of a new drug, and the high attrition rates associated with this developmental process, there is an intense effort by academic and industrial researchers to find novel ways for more effective drug development schemes. The first step in the discovery process of a new drug is the identification of the lead compound. The modern research tendency is to avoid the synthesis of new molecules based on chemical intuition, which is time and cost consuming, and instead to apply in silico rational drug design. This approach reduces the consumables and human personnel involved in the initial steps of the drug design. In this review real examples from our research activity aiming to discover new leads will be given for various dire warnings diseases. There is no recipe to follow for discovering new leads. The strategy to be followed depends on the knowledge of the studied system and the experience of the researchers. The described examples constitute successful and unsuccessful efforts and reflect the reality which medicinal chemists have to face in drug design and development. The drug stability is also discussed in both organic molecules and metallotherapeutics. This is an important issue in drug discovery as drug metabolism in the body can lead to various toxic and undesired molecules.

Technique on rationalization of using electricity and cases

International Nuclear Information System (INIS)

1988-04-01

This book deals with rationalization of using electric and cases. It is divided into four parts. The first part introduces necessity and of progression rationalization of using electric. The second part describes the technique on rationalization of using electric with management of electric energy. The third part depicts domestic cases of rationalization on using of electric such as substation and motor. The last part also introduces foreign cases of rationalization on using of electric with measure of generator circuit, design of motor, design of lighting and design of other equipment.

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

KAUST Repository

Chen, Mark S.

2013-10-22

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

Designing components using smartMOVE electroactive polymer technology

Science.gov (United States)

Rosenthal, Marcus; Weaber, Chris; Polyakov, Ilya; Zarrabi, Al; Gise, Peter

2008-03-01

Designing components using SmartMOVE TM electroactive polymer technology requires an understanding of the basic operation principles and the necessary design tools for integration into actuator, sensor and energy generation applications. Artificial Muscle, Inc. is collaborating with OEMs to develop customized solutions for their applications using smartMOVE. SmartMOVE is an advanced and elegant way to obtain almost any kind of movement using dielectric elastomer electroactive polymers. Integration of this technology offers the unique capability to create highly precise and customized motion for devices and systems that require actuation. Applications of SmartMOVE include linear actuators for medical, consumer and industrial applications, such as pumps, valves, optical or haptic devices. This paper will present design guidelines for selecting a smartMOVE actuator design to match the stroke, force, power, size, speed, environmental and reliability requirements for a range of applications. Power supply and controller design and selection will also be introduced. An overview of some of the most versatile configuration options will be presented with performance comparisons. A case example will include the selection, optimization, and performance overview of a smartMOVE actuator for the cell phone camera auto-focus and proportional valve applications.

Molecular Design of Antifouling Polymer Brushes Using Sequence-Specific Peptoids.

Science.gov (United States)

Lau, King Hang Aaron; Sileika, Tadas S; Park, Sung Hyun; Sousa, Ana Maria Leal; Burch, Patrick; Szleifer, Igal; Messersmith, Phillip B

2015-01-07

Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevent non-specific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N-substituted glycine) "peptoids" are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platform for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with a different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs were found to give rise to distinct but subtle differences in properties. The results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.

Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

Science.gov (United States)

Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

2016-06-01

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Alkali/Surfactant/ Polymer Process: Effects of Slug Size, Core Length and a Chase Polymer Le procédé alkali/surfactant/polymère : effets de la taille du bouchon, de la longueur de la carotte et d'un polymère de déplacement

Directory of Open Access Journals (Sweden)

Green K. A.

2006-11-01

Full Text Available An experimental study was conducted to examine the effects of slug size, core length, and a chase polymer on the effectiveness of the alkali/surfactant/polymer (A/S/P process in recovering waterflood residual oil. Core flood experiments were conducted with unfired linear Berea sandstone cores. The tertiary oil recovery, oil cut, pressure drop, and chemical propagation were measured for each flood. Tertiary oil recovery significantly increased with the slug size up to 0. 5 of a pore volume. Increasing the slug size further resulted in a smaller incremental increase in oil recovery. A slight increase in tertiary oil recovery was obtained when small size A/S/P slugs were followed with achase polymer having a viscosity higher than the slug. The lack of oil recovery with small A/S/P slugs was due to the consumption and dilution of the injected chemicals, especially the synthetic surfactant, due to adsorption and dispersion. Increasing the core length by a factor of 4. 5 (from 9 to 40. 6 cm had no significant effect on tertiary oil recovery. Chemical propagation was found to be a function of core length (i. e. , core Peclet number and the size of the chase polymer slug. Increasing core length and employing a chase polymer maintained the integrity of the A/S/P slug by decreasing the effect of dispersion and minimizing the influence of viscous fingering at the tail of the A/S/P slug. Une étude expérimentale a été effectuée pour examiner les effets de la taille du bouchon, de la longueur de la carotte et de l'emploi d'un polymère de déplacement sur l'efficacité du procédé A/S/P (alkali/surfactant/polymère dans la récupération d'huile résiduelle par injection d'eau. Les expériences d'injection ont été faites avec des carottes rectilignes en grès de Berea vert. La récupération tertiaire du pétrole, la présence d'eau, la perte de charge et la propagation chimique ont été mesurées pour chaque injection. La récupération tertiaire du

Rational design of the exchange-spring permanent magnet.

Science.gov (United States)

Jiang, J S; Bader, S D

2014-02-12

The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

Rational design of the exchange-spring permanent magnet

International Nuclear Information System (INIS)

Jiang, J S; Bader, S D

2014-01-01

The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH) max , while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH) max . The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication. (paper)

Does decision documentation help junior designers rationalize their decisions? A comparative multiple-case study

OpenAIRE

Heesch, U. van; Avgeriou, P.; Tang, A.

2013-01-01

Software architecture design is challenging, especially for junior software designers. Lacking practice and experience, junior designers need process support in order to make rational architecture decisions. In this paper, we present the results of a comparative multiple-case study conducted to find out if decision viewpoints from van Heesch et al. (2012, in press) can provide such a support. The case study was conducted with four teams of software engineering students working in industrial s...

Principles underlying rational design of live attenuated influenza vaccines

Science.gov (United States)

Jang, Yo Han

2012-01-01

Despite recent innovative advances in molecular virology and the developments of vaccines, influenza virus remains a serious burden for human health. Vaccination has been considered a primary countermeasure for prevention of influenza infection. Live attenuated influenza vaccines (LAIVs) are particularly attracting attention as an effective strategy due to several advantages over inactivated vaccines. Cold-adaptation, as a classical means for attenuating viral virulence, has been successfully used for generating safe and effective donor strains of LAIVs against seasonal epidemics and occasional pandemics. Recently, the advent of reverse genetics technique expedited a variety of rational strategies to broaden the pool of LAIVs. Considering the breadth of antigenic diversity of influenza virus, the pool of LAIVs is likely to equip us with better options for controlling influenza pandemics. With a brief reflection on classical attenuating strategies used at the initial stage of development of LAIVs, especially on the principles underlying the development of cold-adapted LAIVs, we further discuss and outline other attenuation strategies especially with respect to the rationales for attenuation, and their practicality for mass production. Finally, we propose important considerations for a rational vaccine design, which will provide us with practical guidelines for improving the safety and effectiveness of LAIVs. PMID:23596576

Standby Gasoline Rationing Plan

Energy Technology Data Exchange (ETDEWEB)

None

1980-06-01

The final rules adopted by the President for a Standby Gasoline Rationing Plan are presented. The plan provides that eligibility for ration allotments will be determined primarily on the basis of motor vehicle registrations, taking into account historical differences in the use of gasoline among states. The regulations also provide authority for supplemental allotments to firms so that their allotment will equal a specified percentage of gasoline use during a base period. Priority classifications, i.e., agriculture, defense, etc., are established to assure adequate gasoline supplies for designated essential services. Ration rights must be provided by end-users to their suppliers for each gallon sold. DOE will regulate the distribution of gasoline at the wholesale level according to the transfer by suppliers of redeemed ration rights and the gasoline allocation regulations. Ration rights are transferable. A ration banking system is created to facilitate transfers of ration rights. Each state will be provided with a reserve of ration rights to provide for hardship needs and to alleviate inequities. (DC)

Rationally designed synthetic protein hydrogels with predictable mechanical properties.

Science.gov (United States)

Wu, Junhua; Li, Pengfei; Dong, Chenling; Jiang, Heting; Bin Xue; Gao, Xiang; Qin, Meng; Wang, Wei; Bin Chen; Cao, Yi

2018-02-12

Designing synthetic protein hydrogels with tailored mechanical properties similar to naturally occurring tissues is an eternal pursuit in tissue engineering and stem cell and cancer research. However, it remains challenging to correlate the mechanical properties of protein hydrogels with the nanomechanics of individual building blocks. Here we use single-molecule force spectroscopy, protein engineering and theoretical modeling to prove that the mechanical properties of protein hydrogels are predictable based on the mechanical hierarchy of the cross-linkers and the load-bearing modules at the molecular level. These findings provide a framework for rationally designing protein hydrogels with independently tunable elasticity, extensibility, toughness and self-healing. Using this principle, we demonstrate the engineering of self-healable muscle-mimicking hydrogels that can significantly dissipate energy through protein unfolding. We expect that this principle can be generalized for the construction of protein hydrogels with customized mechanical properties for biomedical applications.

Design of Polymer Wavelength Splitter 1310 nm/1550 nm Based on Multimode Interferences

Directory of Open Access Journals (Sweden)

V. Prajzler

2010-12-01

Full Text Available We report about design of 1x2 1310/1550 nm optical wavelength division multiplexer based on polymer waveguides. The polymer splitter was designed by using RSoft software based on beam propagation method. Epoxy novolak resin polymer was used as core waveguides layer, silicon substrate with silica layer was used as buffer layer and polymethylmethacrylate was used as protection cover layer. The simulation shows that the output energy for the fundamental mode is 67.1 % for 1310 nm and 67.8 % for 1550 nm wavelength.

Solution-processable ambipolar diketopyrrolopyrrole-selenophene polymer with unprecedentedly high hole and electron mobilities.

Science.gov (United States)

Lee, Junghoon; Han, A-Reum; Kim, Jonggi; Kim, Yiho; Oh, Joon Hak; Yang, Changduk

2012-12-26

There is a fast-growing demand for polymer-based ambipolar thin-film transistors (TFTs), in which both n-type and p-type transistor operations are realized in a single layer, while maintaining simplicity in processing. Research progress toward this end is essentially fueled by molecular engineering of the conjugated backbones of the polymers and the development of process architectures for device fabrication, which has recently led to hole and electron mobilities of more than 1.0 cm(2) V(-1) s(-1). However, ambipolar polymers with even higher performance are still required. By taking into account both the conjugated backbone and side chains of the polymer component, we have developed a dithienyl-diketopyrrolopyrrole (TDPP) and selenophene containing polymer with hybrid siloxane-solubilizing groups (PTDPPSe-Si). A synergistic combination of rational polymer backbone design, side-chain dynamics, and solution processing affords an enormous boost in ambipolar TFT performance, resulting in unprecedentedly high hole and electron mobilities of 3.97 and 2.20 cm(2) V(-1) s(-1), respectively.

  A rationally designed tyrosine hydroxylase DNA vaccine induces specific antineuroblastoma immunity

DEFF Research Database (Denmark)

Huebener, Nicole; Fest, Stefan; Strandsby, Anne Bystrup

2008-01-01

Therapeutic vaccination against tumor antigens without induction of autoimmunity remains a major challenge in cancer immunotherapy. Here, we show for the first time effective therapeutic vaccination followed by suppression of established spontaneous neuroblastoma metastases using a tyrosine...... show effective therapeutic vaccination against neuroblastoma with a novel rationally designed TH minigene vaccine without induction of autoimmunity providing an important baseline for future clinical application of this strategy....

Rational Design of High-Performance Wide-Bandgap (≈2 eV) Polymer Semiconductors as Electron Donors in Organic Photovoltaics Exhibiting High Open Circuit Voltages (≈1 V).

Science.gov (United States)

Chochos, Christos L; Katsouras, Athanasios; Gasparini, Nicola; Koulogiannis, Chrysanthos; Ameri, Tayebeh; Brabec, Christoph J; Avgeropoulos, Apostolos

2017-01-01

Systematic optimization of the chemical structure of wide-bandgap (≈2.0 eV) "donor-acceptor" copolymers consisting of indacenodithiophene or indacenodithieno[3,2-b]thiophene as the electron-rich unit and thieno[3,4-c]pyrrole-4,6-dione as the electron-deficient moiety in terms of alkyl side chain engineering and distance of the electron-rich and electron-deficient monomers within the repeat unit of the polymer chain results in high-performance electron donor materials for organic photovoltaics. Specifically, preliminary results demonstrate extremely high open circuit voltages (V oc s) of ≈1.0 V, reasonable short circuit current density (J sc ) of around 11 mA cm -2 , and moderate fill factors resulting in efficiencies close to 6%. All the devices are fabricated in an inverted architecture with the photoactive layer processed by doctor blade equipment, showing the compatibility with roll-to-roll large-scale manufacturing processes. From the correlation of the chemical structure-optoelectronic properties-photovoltaic performance, a rational guide toward further optimization of the chemical structure in this family of copolymers, has been achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Residualization Rates of Near Infrared Dyes for the Rational Design of Molecular Imaging Agents

Science.gov (United States)

Cilliers, Cornelius; Liao, Jianshan; Atangcho, Lydia; Thurber, Greg M.

2016-01-01

Purpose Near infrared (NIR) fluorescence imaging is widely used for tracking antibodies and biomolecules in vivo. Clinical and preclinical applications include intraoperative imaging, tracking therapeutics, and fluorescent labeling as a surrogate for subsequent radiolabeling. Despite their extensive use, one of the fundamental properties of NIR dyes, the residualization rate within cells following internalization, has not been systematically studied. This rate is required for the rational design of probes and proper interpretation of in vivo results. Procedures In this brief report, we measure the cellular residualization rate of eight commonly used dyes encompassing three core structures (cyanine, BODIPY, and oxazine/thiazine/carbopyronin). Results We identify residualizing (half-life > 24 hrs) and non-residualizing dyes (half-life < 24 hrs) in both the far red (~650-680 nm) and near infrared (~740-800 nm) regions. Conclusions This data will allow researchers to independently and rationally select the wavelength and residualizing nature of dyes for molecular imaging agent design. PMID:25869081

Residualization Rates of Near-Infrared Dyes for the Rational Design of Molecular Imaging Agents.

Science.gov (United States)

Cilliers, Cornelius; Liao, Jianshan; Atangcho, Lydia; Thurber, Greg M

2015-12-01

Near-infrared (NIR) fluorescence imaging is widely used for tracking antibodies and biomolecules in vivo. Clinical and preclinical applications include intraoperative imaging, tracking therapeutics, and fluorescent labeling as a surrogate for subsequent radiolabeling. Despite their extensive use, one of the fundamental properties of NIR dyes, the residualization rate within cells following internalization, has not been systematically studied. This rate is required for the rational design of probes and proper interpretation of in vivo results. In this brief report, we measure the cellular residualization rate of eight commonly used dyes encompassing three core structures (cyanine, boron-dipyrromethene (BODIPY), and oxazine/thiazine/carbopyronin). We identify residualizing (half-life >24 h) and non-residualizing (half-life <24 h) dyes in both the far-red (~650-680 nm) and near-infrared (~740-800 nm) regions. This data will allow researchers to independently and rationally select the wavelength and residualizing nature of dyes for molecular imaging agent design.

Design for Additive Bio-Manufacturing: From Patient-Specific Medical Devices to Rationally Designed Meta-Biomaterials.

Science.gov (United States)

Zadpoor, Amir A

2017-07-25

Recent advances in additive manufacturing (AM) techniques in terms of accuracy, reliability, the range of processable materials, and commercial availability have made them promising candidates for production of functional parts including those used in the biomedical industry. The complexity-for-free feature offered by AM means that very complex designs become feasible to manufacture, while batch-size-indifference enables fabrication of fully patient-specific medical devices. Design for AM (DfAM) approaches aim to fully utilize those features for development of medical devices with substantially enhanced performance and biomaterials with unprecedented combinations of favorable properties that originate from complex geometrical designs at the micro-scale. This paper reviews the most important approaches in DfAM particularly those applicable to additive bio-manufacturing including image-based design pipelines, parametric and non-parametric designs, metamaterials, rational and computationally enabled design, topology optimization, and bio-inspired design. Areas with limited research have been identified and suggestions have been made for future research. The paper concludes with a brief discussion on the practical aspects of DfAM and the potential of combining AM with subtractive and formative manufacturing processes in so-called hybrid manufacturing processes.

Design for Additive Bio-Manufacturing: From Patient-Specific Medical Devices to Rationally Designed Meta-Biomaterials

Directory of Open Access Journals (Sweden)

Amir A. Zadpoor

2017-07-01

Full Text Available Recent advances in additive manufacturing (AM techniques in terms of accuracy, reliability, the range of processable materials, and commercial availability have made them promising candidates for production of functional parts including those used in the biomedical industry. The complexity-for-free feature offered by AM means that very complex designs become feasible to manufacture, while batch-size-indifference enables fabrication of fully patient-specific medical devices. Design for AM (DfAM approaches aim to fully utilize those features for development of medical devices with substantially enhanced performance and biomaterials with unprecedented combinations of favorable properties that originate from complex geometrical designs at the micro-scale. This paper reviews the most important approaches in DfAM particularly those applicable to additive bio-manufacturing including image-based design pipelines, parametric and non-parametric designs, metamaterials, rational and computationally enabled design, topology optimization, and bio-inspired design. Areas with limited research have been identified and suggestions have been made for future research. The paper concludes with a brief discussion on the practical aspects of DfAM and the potential of combining AM with subtractive and formative manufacturing processes in so-called hybrid manufacturing processes.

One-pot synthesis of water soluble iron nanoparticles using rationally-designed peptides and ligand release.

Science.gov (United States)

Papst, Stefanie; Cheong, Soshan; Banholzer, Moritz J; Brimble, Margaret A; Williams, David E; Tilley, Richard D

2013-05-18

Herein we report the rational design of new phosphopeptides for control of nucleation, growth and aggregation of water-soluble, superparamagnetic iron-iron oxide core-shell nanoparticles. The use of the designed peptides enables a one-pot synthesis that avoids utilizing unstable or toxic iron precursors, organic solvents, and the need for exchange of capping agent after synthesis of the NPs.

Diketopyrrolopyrrole Polymers for Organic Solar Cells.

Science.gov (United States)

Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2016-01-19

Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with

Design and development of polyamine polymer for harvesting microalgae for biofuels production

International Nuclear Information System (INIS)

Gupta, S.K.; Kumar, M.; Guldhe, A.; Ansari, F.A.; Rawat, I.; Kanney, K.; Bux, F.

2014-01-01

Highlights: • A low cost, high molecular weight cationic polymer was designed and developed for microalgal harvesting. • The polyamine polymer showed high flocculation efficiency for Scenedesmus sp. in comparison with chitosan and alum. • Such polymers could be preferred over other flocculants for microalgal harvesting for low value products such as biodiesel. • The polymer has not shown any deteriorating effect on lipid recovery and FAME profile of Scenedesmus sp. • Polyamine flocculant could be a cost effective option for harvesting of microalgal biomass for sustainable energy production. - Abstract: Research findings of the past few decades on the cultivation of microalgae for biodiesel production from laboratory to pilot scale microalgal cultivation have translated into empirical hope of developing an eco-friendly biofuel from algae. As far as economic sustainability is concerned, harvesting of microalgae is one of the most energy extensive processes and thus a major challenge, being faced by this industry. In our study, we designed and developed a quaternary ammonium salt based cationic polymer and evaluated its effectiveness for freshwater microalgae harvesting. An epichlorohydrin-n,n-diisopropylamine-dimethylamine polymer with high viscosity (1040 cps) was synthesized. The flocculation performance of this polyamine polymer was evaluated in terms of biomass recovery efficiency of microalgae (Scenedesmus sp.), its effect on lipid yield and composition. The results revealed that due to high molecular weight, the biomass recovery efficiency of the polymer was achieved >90% at a very small dose of 8 mg/L whereas similar biomass recovery efficiency of chitosan and alum were achieved at 80 and 250 mg/L respectively. The presence of functional quaternary amine and hydroxyl groups played an important role in electric charge neutralization of microalgal cells, hence the improved microalgal flocculation performance in comparison to the natural flocculants but

Development of a Preventive HIV Vaccine Requires Solving Inverse Problems Which Is Unattainable by Rational Vaccine Design

Directory of Open Access Journals (Sweden)

Marc H. V. Van Regenmortel

2018-01-01

Full Text Available Hypotheses and theories are essential constituents of the scientific method. Many vaccinologists are unaware that the problems they try to solve are mostly inverse problems that consist in imagining what could bring about a desired outcome. An inverse problem starts with the result and tries to guess what are the multiple causes that could have produced it. Compared to the usual direct scientific problems that start with the causes and derive or calculate the results using deductive reasoning and known mechanisms, solving an inverse problem uses a less reliable inductive approach and requires the development of a theoretical model that may have different solutions or none at all. Unsuccessful attempts to solve inverse problems in HIV vaccinology by reductionist methods, systems biology and structure-based reverse vaccinology are described. The popular strategy known as rational vaccine design is unable to solve the multiple inverse problems faced by HIV vaccine developers. The term “rational” is derived from “rational drug design” which uses the 3D structure of a biological target for designing molecules that will selectively bind to it and inhibit its biological activity. In vaccine design, however, the word “rational” simply means that the investigator is concentrating on parts of the system for which molecular information is available. The economist and Nobel laureate Herbert Simon introduced the concept of “bounded rationality” to explain why the complexity of the world economic system makes it impossible, for instance, to predict an event like the financial crash of 2007–2008. Humans always operate under unavoidable constraints such as insufficient information, a limited capacity to process huge amounts of data and a limited amount of time available to reach a decision. Such limitations always prevent us from achieving the complete understanding and optimization of a complex system that would be needed to achieve a truly

Rational modular design of metabolic network for efficient production of plant polyphenol pinosylvin.

Science.gov (United States)

Wu, Junjun; Zhang, Xia; Zhu, Yingjie; Tan, Qinyu; He, Jiacheng; Dong, Mingsheng

2017-05-03

Efficient biosynthesis of the plant polyphenol pinosylvin, which has numerous applications in nutraceuticals and pharmaceuticals, is necessary to make biological production economically viable. To this end, an efficient Escherichia coli platform for pinosylvin production was developed via a rational modular design approach. Initially, different candidate pathway enzymes were screened to construct de novo pinosylvin pathway directly from D-glucose. A comparative analysis of pathway intermediate pools identified that this initial construct led to the intermediate cinnamic acid accumulation. The pinosylvin synthetic pathway was then divided into two new modules separated at cinnamic acid. Combinatorial optimization of transcriptional and translational levels of these two modules resulted in a 16-fold increase in pinosylvin titer. To further improve the concentration of the limiting precursor malonyl-CoA, the malonyl-CoA synthesis module based on clustered regularly interspaced short palindromic repeats interference was assembled and optimized with other two modules. The final pinosylvin titer was improved to 281 mg/L, which was the highest pinosylvin titer even directly from D-glucose without any additional precursor supplementation. The rational modular design approach described here could bolster our capabilities in synthetic biology for value-added chemical production.

Cofactor specificity switch in Shikimate dehydrogenase by rational design and consensus engineering.

Science.gov (United States)

García-Guevara, Fernando; Bravo, Iris; Martínez-Anaya, Claudia; Segovia, Lorenzo

2017-08-01

Consensus engineering has been used to design more stable variants using the most frequent amino acid at each site of a multiple sequence alignment; sometimes consensus engineering modifies function, but efforts have mainly been focused on studying stability. Here we constructed a consensus Rossmann domain for the Shikimate dehydrogenase enzyme; separately we decided to switch the cofactor specificity through rational design in the Escherichia coli Shikimate dehydrogenase enzyme and then analyzed the effect of consensus mutations on top of our design. We found that consensus mutations closest to the 2' adenine moiety increased the activity in our design. Consensus engineering has been shown to result in more stable proteins and our findings suggest it could also be used as a complementary tool for increasing or modifying enzyme activity during design. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Rational Emotive Education

Science.gov (United States)

Knaus, William

1977-01-01

Rational Emotive Education--an outgrowth of theories developed by Albert Ellis--is a teaching design of mental health concepts and problem-solving activities designed to help students to approach and cope with their problems through experiential learning, via a structured, thematic sequence of emotive education lessons. (MJB)

Full factorial design analysis of carbon nanotube polymer-cement composites

Directory of Open Access Journals (Sweden)

Fábio de Paiva Cota

2012-08-01

Full Text Available The work described in this paper is related to the effect of adding carbon nanotubes (CNT on the mechanical properties of polymer-cement composites. A full factorial design has been performed on 160 samples to identify the contribution provided by the following factors: polymeric phase addition, CNT weight addition and water/cement ratio. The response parameters of the full factorial design were the bulk density, apparent porosity, compressive strength and elastic modulus of the polymer-cement-based nanocomposites. All the factors considered in this analysis affected significantly the bulk density and apparent porosity of the composites. The compressive strength and elastic modulus were affected primarily by the cross-interactions between polymeric phase and CNT additions, and the water/cement ratio with polymeric phase factors.

Design and Modeling of Symmetric Three Branch Polymer Planar Optical Power Dividers

Directory of Open Access Journals (Sweden)

V. Prajzler

2013-04-01

Full Text Available Two types of polymer-based three-branch symmetric planar optical power dividers (splitters were designed, multimode interference (MMI splitter and triangular shape-spacing splitter. By means of modeling the real structures were simulated as made of Epoxy Novolak Resin on silicon substrate, with silica buffer layer and polymethylmethacrylate as protection cover layer. The design of polymer waveguide structure was done by Beam Propagation Method. After comparing properties of both types of the splitters we have demonstrated that our new polymer based triangular shaped splitter can work simultaneously in broader spectrum, the only condition would be that the waveguides are single-mode guiding. It practically means that, what concerns communication wavelengths, it can on principle simultaneously operate at two mainly used wavelengths, 1310 and 1550 nm.

Star polymer-based unimolecular micelles and their application in bio-imaging and diagnosis.

Science.gov (United States)

Jin, Xin; Sun, Pei; Tong, Gangsheng; Zhu, Xinyuan

2018-02-03

As a novel kind of polymer with covalently linked core-shell structure, star polymers behave in nanostructure in aqueous medium at all concentration range, as unimolecular micelles at high dilution condition and multi-micelle aggregates in other situations. The unique morphologies endow star polymers with excellent stability and functions, making them a promising platform for bio-application. A variety of functions including imaging and therapeutics can be achieved through rational structure design of star polymers, and the existence of plentiful end-groups on shell offers the opportunity for further modification. In the last decades, star polymers have become an attracting platform on fabrication of novel nano-systems for bio-imaging and diagnosis. Focusing on the specific topology and physicochemical properties of star polymers, we have reviewed recent development of star polymer-based unimolecular micelles and their bio-application in imaging and diagnosis. The main content of this review summarizes the synthesis of integrated architecture of star polymers and their self-assembly behavior in aqueous medium, focusing especially on the recent advances on their bio-imaging application and diagnosis use. Finally, we conclude with remarks and give some outlooks for further exploration in this field. Copyright © 2018 Elsevier Ltd. All rights reserved.

25th anniversary article: CVD polymers: a new paradigm for surface modification and device fabrication.

Science.gov (United States)

Coclite, Anna Maria; Howden, Rachel M; Borrelli, David C; Petruczok, Christy D; Yang, Rong; Yagüe, Jose Luis; Ugur, Asli; Chen, Nan; Lee, Sunghwan; Jo, Won Jun; Liu, Andong; Wang, Xiaoxue; Gleason, Karen K

2013-10-11

Well-adhered, conformal, thin (polymers can be achieved on virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. In CVD polymerization, the monomer(s) are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, and thickness control. Initiated-CVD shows successful results in terms of rationally designed micro- and nanoengineered materials to control molecular interactions at material surfaces. The success of oxidative-CVD is mainly demonstrated for the deposition of organic conducting and semiconducting polymers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring the role of peptides in polymer-based gene delivery.

Science.gov (United States)

Sun, Yanping; Yang, Zhen; Wang, Chunxi; Yang, Tianzhi; Cai, Cuifang; Zhao, Xiaoyun; Yang, Li; Ding, Pingtian

2017-09-15

Polymers are widely studied as non-viral gene vectors because of their strong DNA binding ability, capacity to carry large payload, flexibility of chemical modifications, low immunogenicity, and facile processes for manufacturing. However, high cytotoxicity and low transfection efficiency substantially restrict their application in clinical trials. Incorporating functional peptides is a promising approach to address these issues. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we systematically summarize the role of peptides in polymer-based gene delivery, and elaborate how to rationally design polymer-peptide based gene delivery vectors. Polymers are widely studied as non-viral gene vectors, but suffer from high cytotoxicity and low transfection efficiency. Incorporating short, bioactive peptides into polymer-based gene delivery systems can address this issue. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we highlight the peptides' roles in polymer-based gene delivery, and elaborate how to utilize various functional peptides to enhance the transfection efficiency of polymers. The optimized peptide-polymer vectors should be able to alter their structures and functions according to biological microenvironments and utilize inherent intracellular pathways of cells, and consequently overcome the barriers during gene delivery to enhance transfection efficiency. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rational design of capillary-driven flows for paper-based microfluidics.

Science.gov (United States)

Elizalde, Emanuel; Urteaga, Raúl; Berli, Claudio L A

2015-05-21

The design of paper-based assays that integrate passive pumping requires a precise programming of the fluid transport, which has to be encoded in the geometrical shape of the substrate. This requirement becomes critical in multiple-step processes, where fluid handling must be accurate and reproducible for each operation. The present work theoretically investigates the capillary imbibition in paper-like substrates to better understand fluid transport in terms of the macroscopic geometry of the flow domain. A fluid dynamic model was derived for homogeneous porous substrates with arbitrary cross-sectional shapes, which allows one to determine the cross-sectional profile required for a prescribed fluid velocity or mass transport rate. An extension of the model to slit microchannels is also demonstrated. Calculations were validated by experiments with prototypes fabricated in our lab. The proposed method constitutes a valuable tool for the rational design of paper-based assays.

Fundamental molecular design for precise control of thermoresponsiveness of organic polymers by using ternary systems.

Science.gov (United States)

Amemori, Shogo; Kokado, Kenta; Sada, Kazuki

2012-05-23

The de novo design of thermosensitive polymers in solution has been achieved by using the addition of small organic molecules (or "effectors"). Hydrogen bonding as an attractive polymer-polymer or polymer-effector interaction substantially dominates the responsivity, causing facile switching between LCST-type and UCST-type phase transitions, control of the transition temperature, and further coincidence of the two transitions. Small molecules having a high affinity for the polymer induce UCST-type phase behavior, whereas those having a low affinity for the polymer showed LCST-type phase behavior.

Considerations for the rational design of a Chlamydia vaccine.

Science.gov (United States)

Liang, Steven; Bulir, David; Kaushic, Charu; Mahony, James

2017-04-03

Chlamydia trachomatis is the leading cause of preventable blindness and the most common bacterial sexually transmitted infection. Remarkable progress in vaccine research over the past six decades has led to the advancement of novel C. trachomatis vaccine candidates into clinical trials. However, many questions regarding the role of specific cellular populations and molecular mechanisms in protective immunity against human C. trachomatis genital tract infections remain unanswered. Biomarkers of vaccine induced protective immunity are elusive in humans, while a cautionary message on the translatability of data obtained from current animal models has emanated from vaccine research and development efforts against other important human pathogens. In this commentary, we highlight recent advances in Chlamydia vaccine development and discuss their implications in the context of a rational approach to the design of a human C. trachomatis vaccine.

Development of rational design technique for frame steel structure combining seismic resistance and economic performance

International Nuclear Information System (INIS)

Kato, Motoki; Morishita, Kunihiro; Shimono, Masaki; Chuman, Yasuharu; Okafuji, Takashi; Monaka, Toshiaki

2015-01-01

Anti-seismic designs have been applied to plant support steel frames for years. Today, a rational structure that further improves seismic resistance and ensures economic performance is required in response to an increase of seismic load on the assumption of predicted future massive earthquakes. For satisfying this requirement, a steel frame design method that combines a steel frame weight minimizing method, which enables economic design through simultaneous minimization of multiple steel frame materials, and a seismic response control design technology that improves seismic resistance has been established. Its application in the design of real structures has been promoted. This paper gives an overview of this design technology and presents design examples to which this design technology is applied. (author)

Low Band Gap Polymers for Roll-to-Roll Coated Organic Photovoltaics – Design, Synthesis and Characterization

DEFF Research Database (Denmark)

Bundgaard, Eva; Hagemann, Ole; Jørgensen, Mikkel

2011-01-01

In this paper we present the design and synthesis of 25 new low band gap polymers. The polymers were characterized by UV-vis spectroscopy which showed optical band gaps of 2.0–0.9 eV. The polymers which were soluble enough were applied in organic photovoltaics, both small area devices with a spin...... coated active layer and in large area modules where all layers including the active layer were either roll-to-roll coated or printed. These experiments showed that the design of polymers compatible with roll-toroll coating is not straightforward and that there are various issues such as donor...

Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

Science.gov (United States)

Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

2016-09-01

Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

Hydrophobic polymers for orodispersible films: a quality by design approach.

Science.gov (United States)

Borges, Ana Filipa; Silva, Branca M A; Silva, Cláudia; Coelho, Jorge F J; Simões, Sérgio

2016-10-01

To develop orodispersible films (ODF) based on hydrophobic polymers with higher stability to ordinary environmental humidity conditions without compromising their fast disintegration time. A quality by design approach was applied to screen three different formulations each one based on a different hydrophobic polymer: polyvinyl acetate, methacrylate-based copolymer and shellac. The screening formulations were characterized regarding their mechanical properties, residual water content, disintegration time and appearance, in order to find a suitable ODF formulation according to established critical quality attributes. The selected critical process parameters for the selection of appropriate ODF formulations were the percentage of the different excipients and the plasticizer type. Three hydrophobic-based matrices with fast disintegration were developed. These were generically composed by a hydrophobic polymer, a stabilizer, a disintegrant and a plasticizer. It verified that the common components within the three different formulations behave differently depending on the system/chemical environment that they were included. It was shown that it is possible to develop oral films based on hydrophobic polymers with fast disintegration time, good texture and appearance, breaking a paradigm of the ODF research field.

Design, synthesis and photovoltaic properties of a series of new acceptor-pended conjugated polymers

Institute of Scientific and Technical Information of China (English)

Zhihong; Wu; Yongxiang; Zhu; Wei; Li; Yunping; Huang; Junwu; Chen; Chunhui; Duan; Fei; Huang; Yong; Cao

2016-01-01

A series of novel acceptor-pended conjugated polymers featuring a newly developed carbazole-derived unit are designed and synthesized. The relationships between chemical structure and optoelectronic properties of the polymers are systematically investigated.The control of UV-Vis absorption spectra and energy levels in resulting polymers are achieved by introducing suitable pended acceptor units. The photovoltaic properties of the resulting polymers are evaluated by blending the polymers with(6,6)-phenyl-C71-butyric acid methyl ester. The resulting solar cells exhibit moderate performances with high open-circuit voltage. Charge transport properties and morphology were investigated to understand the performance of corresponding solar cells.

Application of Absorption Modeling in Rational Design of Drug Product Under Quality-by-Design Paradigm.

Science.gov (United States)

Kesisoglou, Filippos; Mitra, Amitava

2015-09-01

Physiologically based absorption models can be an important tool in understanding product performance and hence implementation of Quality by Design (QbD) in drug product development. In this report, we show several case studies to demonstrate the potential application of absorption modeling in rational design of drug product under the QbD paradigm. The examples include application of absorption modeling—(1) prior to first-in-human studies to guide development of a formulation with minimal sensitivity to higher gastric pH and hence reduced interaction when co-administered with PPIs and/or H2RAs, (2) design of a controlled release formulation with optimal release rate to meet trough plasma concentrations and enable QD dosing, (3) understanding the impact of API particle size distribution on tablet bioavailability and guide formulation design in late-stage development, (4) assess impact of API phase change on product performance to guide specification setting, and (5) investigate the effect of dissolution rate changes on formulation bioperformance and enable appropriate specification setting. These case studies are meant to highlight the utility of physiologically based absorption modeling in gaining a thorough understanding of the product performance and the critical factors impacting performance to drive design of a robust drug product that would deliver the optimal benefit to the patients.

Materials selection in micromechanical design: an application of the Ashby approach

OpenAIRE

Srikar, V.T.; Spearing, S.M.

2003-01-01

The set of materials available to microsystems designers is rapidly expanding. Techniques now exist to introduce and integrate a large number of metals, alloys, ceramics, glasses, polymers, and elastomers into microsystems, motivating the need for a rational approach for materials selection in microsystems design. As a step toward such an approach, we focus on the initial stages of materials selection for micromechanical structures with minimum feature sizes greater than 1 /spl mu/m. The vari...

Rational design of hierarchical ZnO@Carbon nanoflower for high performance lithium ion battery anodes

Science.gov (United States)

liu, Huichao; Shi, Ludi; Li, Dongzhi; Yu, Jiali; Zhang, Han-Ming; Ullah, Shahid; Yang, Bo; Li, Cuihua; Zhu, Caizhen; Xu, Jian

2018-05-01

The rational structure design and strong interfacial bonding are crucially desired for high performance zinc oxide (ZnO)/carbon composite electrodes. In this context, micro-nano secondary structure design and strong dopamine coating strategies are adopted for the fabrication of flower-like ZnO/carbon (ZnO@C nanoflowers) composite electrodes. The results show the ZnO@C nanoflowers (2-6 μm) are assembled by hierarchical ZnO nanosheets (∼27 nm) and continuous carbon framework. The micro-nano secondary architecture can facilitate the penetration of electrolyte, shorten lithium ions diffusion length, and hinder the aggregation of the nanosheets. Moreover, the strong chemical interaction between ZnO and coating carbon layer via C-Zn bond improves structure stability as well as the electronic conductivity. As a synergistic result, when evaluated as lithium ion batteries (LIBs) anode, the ZnO@C nanoflower electrodes show high reversible capacity of ca. 1200 mA h g-1 at 0.1 A g-1 after 80 cycles. As well as good long-cycling stability (638 and 420 mA h g-1 at 1 and 5 A g-1 after 500 cycles, respectively) and excellent rate capability. Therefore, this rational design of ZnO@C nanoflowers electrode is a promising anode for high-performance LIBs.

Effect of Chain Conformation on the Single-Molecule Melting Force in Polymer Single Crystals: Steered Molecular Dynamics Simulations Study.

Science.gov (United States)

Feng, Wei; Wang, Zhigang; Zhang, Wenke

2017-02-28

Understanding the relationship between polymer chain conformation as well as the chain composition within the single crystal and the mechanical properties of the corresponding single polymer chain will facilitate the rational design of high performance polymer materials. Here three model systems of polymer single crystals, namely poly(ethylene oxide) (PEO), polyethylene (PE), and nylon-66 (PA66) have been chosen to study the effects of chain conformation, helical (PEO) versus planar zigzag conformation (PE, PA66), and chain composition (PE versus PA66) on the mechanical properties of a single polymer chain. To do that, steered molecular dynamics simulations were performed on those polymer single crystals by pulling individual polymer chains out of the crystals. Our results show that the patterns of force-extension curve as well as the chain moving mode are closely related to the conformation of the polymer chain in the single crystal. In addition, hydrogen bonds can enhance greatly the force required to stretch the polymer chain out of the single crystal. The dynamic breaking and reformation of multivalent hydrogen bonds have been observed for the first time in PA66 at the single molecule level.

Emerging synthetic strategies for core cross-linked star (CCS) polymers and applications as interfacial stabilizers: bridging linear polymers and nanoparticles.

Science.gov (United States)

Chen, Qijing; Cao, Xueteng; Xu, Yuanyuan; An, Zesheng

2013-10-01

Core cross-linked star (CCS) polymers become increasingly important in polymer science and are evaluated in many value-added applications. However, limitations exist to varied degrees for different synthetic methods. It is clear that improvement in synthetic efficiency is fundamental in driving this field moving even further. Here, the most recent advances are highlighted in synthetic strategies, including cross-linking with cross-linkers of low solubility, polymerization-induced self-assembly in aqueous-based heterogeneous media, and cross-linking via dynamic covalent bonds. The understanding of CCS polymers is also further refined to advocate their role as an intermediate between linear polymers and polymeric nanoparticles, and their use as interfacial stabilizers is rationalized within this context. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rational design of functional and tunable oscillating enzymatic networks

Science.gov (United States)

Semenov, Sergey N.; Wong, Albert S. Y.; van der Made, R. Martijn; Postma, Sjoerd G. J.; Groen, Joost; van Roekel, Hendrik W. H.; de Greef, Tom F. A.; Huck, Wilhelm T. S.

2015-02-01

Life is sustained by complex systems operating far from equilibrium and consisting of a multitude of enzymatic reaction networks. The operating principles of biology's regulatory networks are known, but the in vitro assembly of out-of-equilibrium enzymatic reaction networks has proved challenging, limiting the development of synthetic systems showing autonomous behaviour. Here, we present a strategy for the rational design of programmable functional reaction networks that exhibit dynamic behaviour. We demonstrate that a network built around autoactivation and delayed negative feedback of the enzyme trypsin is capable of producing sustained oscillating concentrations of active trypsin for over 65 h. Other functions, such as amplification, analog-to-digital conversion and periodic control over equilibrium systems, are obtained by linking multiple network modules in microfluidic flow reactors. The methodology developed here provides a general framework to construct dissipative, tunable and robust (bio)chemical reaction networks.

Collapsed polymer-directed synthesis of multicomponent coaxial-like nanostructures

KAUST Repository

Huang, Zhiqi

2016-07-19

Multicomponent colloidal nanostructures (MCNs) exhibit intriguing topologically dependent chemical and physical properties. However, there remain significant challenges in the synthesis of MCNs with high-order complexity. Here we show the development of a general yet scalable approach for the rational design and synthesis of MCNs with unique coaxial-like construction. The site-preferential growth in this synthesis relies on the selective protection of seed nanoparticle surfaces with locally defined domains of collapsed polymers. By using this approach, we produce a gallery of coaxial-like MCNs comprising a shaped Au core surrounded by a tubular metal or metal oxide shell. This synthesis is robust and not prone to variations in kinetic factors of the synthetic process. The essential role of collapsed polymers in achieving anisotropic growth makes our approach fundamentally distinct from others. We further demonstrate that this coaxial-like construction can lead to excellent photocatalytic performance over conventional core–shell-type MCNs.

Collapsed polymer-directed synthesis of multicomponent coaxial-like nanostructures

KAUST Repository

Huang, Zhiqi; Liu, Yijing; Zhang, Qian; Chang, Xiaoxia; Li, Ang; Deng, Lin; Yi, Chenglin; Yang, Yang; Khashab, Niveen M.; Gong, Jinlong; Nie, Zhihong

2016-01-01

Multicomponent colloidal nanostructures (MCNs) exhibit intriguing topologically dependent chemical and physical properties. However, there remain significant challenges in the synthesis of MCNs with high-order complexity. Here we show the development of a general yet scalable approach for the rational design and synthesis of MCNs with unique coaxial-like construction. The site-preferential growth in this synthesis relies on the selective protection of seed nanoparticle surfaces with locally defined domains of collapsed polymers. By using this approach, we produce a gallery of coaxial-like MCNs comprising a shaped Au core surrounded by a tubular metal or metal oxide shell. This synthesis is robust and not prone to variations in kinetic factors of the synthetic process. The essential role of collapsed polymers in achieving anisotropic growth makes our approach fundamentally distinct from others. We further demonstrate that this coaxial-like construction can lead to excellent photocatalytic performance over conventional core–shell-type MCNs.

Testing the rationality assumption using a design difference in the TV game show 'Jeopardy'

OpenAIRE

Sjögren Lindquist, Gabriella; Säve-Söderbergh, Jenny

2006-01-01

Abstract This paper empirically investigates the rationality assumption commonly applied in economic modeling by exploiting a design difference in the game-show Jeopardy between the US and Sweden. In particular we address the assumption of individuals’ capabilities to process complex mathematical problems to find optimal strategies. The vital difference is that US contestants are given explicit information before they act, while Swedish contestants individually need to calculate the same info...

Intrinsically Microporous Polymer Membranes for High Performance Gas Separation

KAUST Repository

Swaidan, Raja

2014-11-01

This dissertation addresses the rational design of intrinsically microporous solutionprocessable polyimides and ladder polymers for highly permeable and highly selective gas transport in cornerstone applications of membrane-based gas separation – that is, air enrichment, hydrogen recovery and natural gas sweetening. By virtue of rigid and contorted chains that pack inefficiently in the solid state, polymers of intrinsic microporosity (PIMs) have the potential to unite the solution-processability, mechanical flexibility and organic tunability of commercially relevant polymers with the microporosity characteristics of porous crystalline materials. The performance enhancements of PIMs over conventional low-free-volume polymers have been primarily permeability-driven, compromising the selectivity essential to commercial viability. An approach to unite high permeability with high selectivity for performance transcending the state-of-the-art in air and hydrogen separations was demonstrated via a fused-ring integration of a three-dimensional, shape persistent triptycene moiety optimally substituted with short, branched isopropyl chains at the 9,10-bridgeheads into a highly inflexible backbone. The resulting polymers exhibited selectivities (i.e., O2/N2, H2/N2, H2/CH4) similar to or higher than commercial materials matched with permeabilities up to three hundred times higher. However, the intra-chain rigidity central to such conventional PIM-design principles was not a singular solution to suppression of CO2-induced plasticization in CO2/CH4 mixedgas separations. Plasticization diminishes the sieving capacity of the membrane, resulting in costly hydrocarbon losses that have significantly limited the commercialization of new polymers. Unexpectedly, the most permeable and selective PIMs designed for air and hydrogen separations strongly plasticized in 50:50 CO2/CH4 mixtures, enduring up to three-fold increases in mixed-gas CH4 permeability by 30 bar and strong drops in

Virus-Like Particle Engineering: From Rational Design to Versatile Applications.

Science.gov (United States)

Ding, Xuanwei; Liu, Dong; Booth, George; Gao, Wei; Lu, Yuan

2018-05-01

As mimicking natural virus structures, virus-like particles (VLPs) have evolved to become a widely accepted technology used for humans which are safe, highly efficacious, and profitable. Several remarkable advantages have been achieved to revolutionize the molecule delivery for diverse applications in nanotechnology, biotechnology, and medicine. Here, the rational structure design, manufacturing process, functionalization strategy, and emerging applications of VLPs is reviewed. The situation and challenges in the VLP engineering, the key development orientation, and future applications have been discussed. To develop a good VLP design concept, the virus/VLP-host interactions need to be examined and the screening methods of the VLP stabilization factors need to be established. The functionalization toolbox can be expanded to fabricate smart, robust, and multifunctional VLPs. Novel robust VLP manufacturing platforms are required to deliver vaccines in resource-poor regions with a significant reduction in the production time and cost. The future applications of VLPs are always driven by the development of emerging technologies and new requirements of modern life. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Routing of individual polymers in designed patterns

DEFF Research Database (Denmark)

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

2015-01-01

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

Rationality of limited rationality : some aggregate implications

OpenAIRE

Uri M. Possen; Mikko Puhakka

1994-01-01

In this paper we let economic agents choose whether to become fully rational or stay boundedly rational. Boundedly rational agents are less sophisticated in their information processing abilities. It is costly to acquire information needed to become fully rational, and thus not all agents are willing to incur those costs. We then explore the aggregate effects of endogenizing the decision whether the agent should or should not become fully rational in handling information. Since fully and boun...

Effect of polymer type on characteristics of buccal tablets using factorial design

Directory of Open Access Journals (Sweden)

O. Esim

2018-01-01

Full Text Available A two factor three level factorial design was used to investigate the effects of carbopol and cationic hydrophilic polymers which have a common use in buccal drug formulations. Statistical models with interaction terms were derived to evaluate influence of carbopol (X1 and chitosan (X2 on tablet disintegration (Y1 and dissolution (Y2, mechanical properties (Y3, swelling (Y4. Tablet disintegration studies were carried out using two different pH environments within buccal region pH limits and also two different commonly used dissolution methods for buccal tablets were also investigated to compare the effect of polymer type on dissolution. Polymer type and ratio affect the characteristics of the buccal tablets due to their different physicochemical behavior at buccal pH. Also significant variances between dissolution profiles for buccal tablets, using either USP Paddle or flow through cell methods were found. These results indicate that both polymer type and ratio as well as combination of them effects the drug behavior in different ways. Keywords: Buccal tablet, Hydrophilic matrix, Effect of polymer, Carbopol, Chitosan

Routing of individual polymers in designed patterns

Science.gov (United States)

Knudsen, Jakob Bach; Liu, Lei; Bank Kodal, Anne Louise; Madsen, Mikael; Li, Qiang; Song, Jie; Woehrstein, Johannes B.; Wickham, Shelley F. J.; Strauss, Maximilian T.; Schueder, Florian; Vinther, Jesper; Krissanaprasit, Abhichart; Gudnason, Daniel; Smith, Anton Allen Abbotsford; Ogaki, Ryosuke; Zelikin, Alexander N.; Besenbacher, Flemming; Birkedal, Victoria; Yin, Peng; Shih, William M.; Jungmann, Ralf; Dong, Mingdong; Gothelf, Kurt V.

2015-10-01

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

Design Principles in Polymer-Fullerene BHJ Solar Cells: PBDTTPD as a Case Study

KAUST Repository

Beaujuge, Pierre

2015-06-29

Among Organic Electronics, solution-processable π-conjugated polymers are proving particularly promising in bulk-heterojunction (BHJ) solar cells with fullerene acceptors such as PCBM.[1] In recent years, great headway has been made in the development of efficient polymer donors across the community, with published power conversion efficiencies (PCE) >8% in single cells and >10% in tandems. In most reports, these systems involve elaborate repeat unit and side chain patterns, and deviating from those patterns induces substantial drops in device PCE. While the range of polymer design parameters that impact BHJ solar cell performance remains a matter of some debate, our recent developments indicate that the combination of side-chain substituents appended to the main chain critically impacts polymer performance. For example, in poly(benzo[1,2-b:4,5-b’]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD), side-chain substituents of various size and branching impart distinct molecular packing distances (i.e., π–π stacking and lamellar spacing), varying degrees of nanostructural order in thin films, and preferential backbone orientation relative to the device substrate.[2-5] While these structural variations seem to correlate with BHJ solar cell performance, with power conversion efficiencies ranging from 4% to 8.5%,[2,3] we believe that other contributing parameters – such as the local conformations between the polymer and the fullerene, and the domain distribution/composition across the BHJ (i.e., pure/mixed phases) – should also be taken into account.[6,7] Other discrete modifications of PBDTTPD’s molecular structure affect polymer performance in BHJ solar cells with PCBM, and our recent developments emphasize how systematic structure-property relationship studies impact the design of efficient polymer donors for BHJ solar cell applications.[8-10] It is important to further our understanding of these effects as we look to continue improving BHJ solar

Rationalization with ruled surfaces in architecture

DEFF Research Database (Denmark)

Steenstrup, Kasper Hornbak

This thesis addresses the problems of rationalizing and segmenting large scale 3D models, and how to handle difficult production constraints in this area. The design choices when constructing large scale architecture are influenced by the budget. Therefore I strive to minimize the amount of time...... and material needed for production. This makes advanced free form architecture viable for low cost projects, allowing the architects to realize their designs. By pre-cutting building blocks using hot wire robots, the amount of milling necessary can be reduced drastically. I do this by rationalizing...

GREEN: A program package for docking studies in rational drug design

Science.gov (United States)

Tomioka, Nobuo; Itai, Akiko

1994-08-01

A program package, GREEN, has been developed that enables docking studies between ligand molecules and a protein molecule. Based on the structure of the protein molecule, the physical and chemical environment of the ligand-binding site is expressed as three-dimensional grid-point data. The grid-point data are used for the real-time evaluation of the protein-ligand interaction energy, as well as for the graphical representation of the binding-site environment. The interactive docking operation is facilitated by various built-in functions, such as energy minimization, energy contribution analysis and logging of the manipulation trajectory. Interactive modeling functions are incorporated for designing new ligand molecules while considering the binding-site environment and the protein-ligand interaction. As an example of the application of GREEN, a docking study is presented on the complex between trypsin and a synthetic trypsin inhibitor. The program package will be useful for rational drug design, based on the 3D structure of the target protein.

Rational Design Approach for Enhancing Higher-Mode Response of a Microcantilever in Vibro-Impacting Mode

Directory of Open Access Journals (Sweden)

Ieva Migliniene

2017-12-01

Full Text Available This paper proposes an approach for designing an efficient vibration energy harvester based on a vibro-impacting piezoelectric microcantilever with a geometric shape that has been rationally modified in accordance with results of dynamic optimization. The design goal is to increase the amplitudes of higher-order vibration modes induced during the vibro-impact response of the piezoelectric transducer, thereby providing a means to improve the energy conversion efficiency and power output. A rational configuration of the energy harvester is proposed and it is demonstrated that the new design retains essential modal characteristics of the optimal microcantilever structures, further providing the added benefit of less costly fabrication. The effects of structural dynamics associated with advantageous exploitation of higher vibration modes are analyzed experimentally by means of laser vibrometry as well as numerically via transient simulations of microcantilever response to random excitation. Electrical characterization results indicate that the proposed harvester outperforms its conventional counterpart (based on the microcantilever of the constant cross-section in terms of generated electrical output. Reported results may serve for the development of impact-type micropower generators with harvesting performance that is enhanced by virtue of self-excitation of large intensity higher-order mode responses when the piezoelectric transducer is subjected to relatively low-frequency excitation with strongly variable vibration magnitudes.

Rationalization and Design of the Complementarity Determining Region Sequences in an Antibody-Antigen Recognition Interface

Science.gov (United States)

Chen, Ing-Chien; Lee, Yu-Ching; Chen, Jun-Bo; Tsai, Keng-Chang; Chen, Ching-Tai; Chang, Jeng-Yih; Yang, Ei-Wen; Hsu, Po-Chiang; Jian, Jhih-Wei; Hsu, Hung-Ju; Chang, Hung-Ju; Hsu, Wen-Lian; Huang, Kai-Fa; Ma, Alex Che; Yang, An-Suei

2012-01-01

Protein-protein interactions are critical determinants in biological systems. Engineered proteins binding to specific areas on protein surfaces could lead to therapeutics or diagnostics for treating diseases in humans. But designing epitope-specific protein-protein interactions with computational atomistic interaction free energy remains a difficult challenge. Here we show that, with the antibody-VEGF (vascular endothelial growth factor) interaction as a model system, the experimentally observed amino acid preferences in the antibody-antigen interface can be rationalized with 3-dimensional distributions of interacting atoms derived from the database of protein structures. Machine learning models established on the rationalization can be generalized to design amino acid preferences in antibody-antigen interfaces, for which the experimental validations are tractable with current high throughput synthetic antibody display technologies. Leave-one-out cross validation on the benchmark system yielded the accuracy, precision, recall (sensitivity) and specificity of the overall binary predictions to be 0.69, 0.45, 0.63, and 0.71 respectively, and the overall Matthews correlation coefficient of the 20 amino acid types in the 24 interface CDR positions was 0.312. The structure-based computational antibody design methodology was further tested with other antibodies binding to VEGF. The results indicate that the methodology could provide alternatives to the current antibody technologies based on animal immune systems in engineering therapeutic and diagnostic antibodies against predetermined antigen epitopes. PMID:22457753

Gleaning Insights from Fecal Microbiota Transplantation and Probiotic Studies for the Rational Design of Combination Microbial Therapies

Science.gov (United States)

Hudson, Lauren E.; Anderson, Sarah E.; Corbett, Anita H.

2016-01-01

SUMMARY Beneficial microorganisms hold promise for the treatment of numerous gastrointestinal diseases. The transfer of whole microbiota via fecal transplantation has already been shown to ameliorate the severity of diseases such as Clostridium difficile infection, inflammatory bowel disease, and others. However, the exact mechanisms of fecal microbiota transplant efficacy and the particular strains conferring this benefit are still unclear. Rationally designed combinations of microbial preparations may enable more efficient and effective treatment approaches tailored to particular diseases. Here we use an infectious disease, C. difficile infection, and an inflammatory disorder, the inflammatory bowel disease ulcerative colitis, as examples to facilitate the discussion of how microbial therapy might be rationally designed for specific gastrointestinal diseases. Fecal microbiota transplantation has already shown some efficacy in the treatment of both these disorders; detailed comparisons of studies evaluating commensal and probiotic organisms in the context of these disparate gastrointestinal diseases may shed light on potential protective mechanisms and elucidate how future microbial therapies can be tailored to particular diseases. PMID:27856521

DNA-inspired hierarchical polymer design: electrostatics and hydrogen bonding in concert.

Science.gov (United States)

Hemp, Sean T; Long, Timothy E

2012-01-01

Nucleic acids and proteins, two of nature's biopolymers, assemble into complex structures to achieve desired biological functions and inspire the design of synthetic macromolecules containing a wide variety of noncovalent interactions including electrostatics and hydrogen bonding. Researchers have incorporated DNA nucleobases into a wide variety of synthetic monomers/polymers achieving stimuli-responsive materials, supramolecular assemblies, and well-controlled macromolecules. Recently, scientists utilized both electrostatics and complementary hydrogen bonding to orthogonally functionalize a polymer backbone through supramolecular assembly. Diverse macromolecules with noncovalent interactions will create materials with properties necessary for biomedical applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and Application of Nanogel-Based Polymer Networks

Science.gov (United States)

Dailing, Eric Alan

Crosslinked polymer networks have wide application in biomaterials, from soft hydrogel scaffolds for cell culture and tissue engineering to glassy, high modulus dental restoratives. Composite materials formed with nanogels as a means for tuning network structure on the nanoscale have been reported, but no investigation into nanogels as the primary network component has been explored to this point. This thesis was dedicated to studying network formation from the direct polymerization of nanogels and investigating applications for these unique materials. Covalently crosslinked polymer networks were synthesized from polymerizable nanogels without the use of reactive small monomers or oligomers. Network properties were controlled by the chemical and physical properties of the nanogel, allowing for materials to be designed from nanostructured macromolecular precursors. Nanogels were synthesized from a thermally initiated solution free radical polymerization of a monomethacrylate, a dimethacrylate, and a thiol-based chain transfer agent. Monomers with a range of hydrophilic and hydrophobic character were copolymerized, and polymerizable groups were introduced through an alcohol-isocyanate click reaction. Nanogels were dispersible in water up to 75 wt%, including nanogels that contained a relatively high fraction of a conventionally water-insoluble component. Nanogels with molecular weights that ranged from 10's to 100's of kDa and hydrodynamic radii between 4 and 10 nm were obtained. Macroscopic crosslinked polymer networks were synthesized from the photopolymerization of methacrylate-functionalized nanogels in inert solvent, which was typically water. The nanogel composition and internal branching density affected both covalent and non-covalent interparticle interactions, which dictated the final mechanical properties of the networks. Nanogels with progressively disparate hydrophilic and hydrophobic character were synthesized to explore the potential for creating

The rational development of molecularly imprinted polymer-based sensors for protein detection.

Science.gov (United States)

Whitcombe, Michael J; Chianella, Iva; Larcombe, Lee; Piletsky, Sergey A; Noble, James; Porter, Robert; Horgan, Adrian

2011-03-01

The detection of specific proteins as biomarkers of disease, health status, environmental monitoring, food quality, control of fermenters and civil defence purposes means that biosensors for these targets will become increasingly more important. Among the technologies used for building specific recognition properties, molecularly imprinted polymers (MIPs) are attracting much attention. In this critical review we describe many methods used for imprinting recognition for protein targets in polymers and their incorporation with a number of transducer platforms with the aim of identifying the most promising approaches for the preparation of MIP-based protein sensors (277 references).

A rationally designed photo-chemo core-shell nanomedicine for inhibiting the migration of metastatic breast cancer cells followed by photodynamic killing.

Science.gov (United States)

Malarvizhi, Giridharan Loghanathan; Chandran, Parwathy; Retnakumari, Archana Payickattu; Ramachandran, Ranjith; Gupta, Neha; Nair, Shantikumar; Koyakutty, Manzoor

2014-04-01

A multifunctional core-shell nanomedicine capable of inhibiting the migratory capacity of metastatic cancer cells followed by imparting cytotoxic stress by photodynamic action is reported. Based on in silico design, we have developed a core-shell nanomedicine comprising of ~80nm size poly(lactic-co-glycolic acid) (PLGA) nano-core encapsulating photosensitizer, m-tetra(hydroxyphenyl)chlorin (mTHPC), and ~20nm size albumin nano-shell encapsulating tyrosine kinase inhibitor, Dasatinib, which impair cancer migration. This system was prepared by a sequential process involving electrospray of polymer core and coacervation of protein shell. Cell studies using metastatic breast cancer cells demonstrated disruption of Src kinase involved in the cancer migration by albumin-dasatinib nano-shell and generation of photoactivated oxidative stress by mTHPC-PLGA nano-core. This unique combinatorial photo-chemo nanotherapy resulted synergistic cytotoxicity in ~99% of the motility-impaired metastatic cells. This approach of blocking cancer migration followed by photodynamic killing using rationally designed nanomedicine is a promising new strategy against cancer metastasis. A multifunctional core-shell nanomedicine capable of inhibiting metastatic cancer cell migration, in addition to inducing photodynamic effects, is described in this paper. The authors document cytotoxicity in approximately 99% of the studied metastatic breast cancer cells. Similar approaches would be a very welcome addition to the treatment protocols of advanced metastatic breast cancer and other types of neoplasms. Copyright © 2014 Elsevier Inc. All rights reserved.

Design Concept of Dialyzer Biomaterials: How to Find Biocompatible Polymers Based on the Biointerfacial Water Structure.

Science.gov (United States)

Tanaka, Masaru

2017-01-01

Although various types of materials have been used widely in dialyzers, most biomaterials lack the desired functional properties to interface with blood and have not been engineered for optimum performance. Therefore, there is increasing demand to develop novel materials to address such problems in the dialysis arena. Numerous parameters of polymeric biomaterials can affect biocompatibility in a controlled manner. The mechanisms responsible for the biocompatibility of polymers at the molecular level have not been clearly demonstrated, although many theoretical and experimental efforts have been made to try and understand them. Moreover, water interactions have been recognized as fundamental for the blood response to contact with polymers. We have proposed the 'intermediate water' concept and hypothesized that intermediate water, which prevents the proteins and blood cells from directly contacting the polymer surface, or nonfreezing water on the polymer surface, plays an important role in the biocompatibility of polymers. This chapter provides an overview of the recent experimental progress of biocompatible polymers measured by thermal, spectroscopic, and surface force techniques. Additionally, it highlights recent developments in the use of biocompatible polymeric biomaterials for dialyzers and provides an overview of the progress made in the design of multifunctional biomedical polymers by controlling the biointerfacial water structure through precision polymer synthesis. Key Messages: Intermediate water was found only in hydrated biopolymers (proteins, polysaccharides, and nucleic acids, DNA and RNA) and hydrated biocompatible synthetic polymers. Intermediate water could be one of the main screening factors for the design of appropriate dialyzer materials. © 2017 S. Karger AG, Basel.

Improving specific activity and thermostability of Escherichia coli phytase by structure-based rational design.

Science.gov (United States)

Wu, Tzu-Hui; Chen, Chun-Chi; Cheng, Ya-Shan; Ko, Tzu-Ping; Lin, Cheng-Yen; Lai, Hui-Lin; Huang, Ting-Yung; Liu, Je-Ruei; Guo, Rey-Ting

2014-04-10

Escherichia coli phytase (EcAppA) which hydrolyzes phytate has been widely applied in the feed industry, but the need to improve the enzyme activity and thermostability remains. Here, we conduct rational design with two strategies to enhance the EcAppA performance. First, residues near the substrate binding pocket of EcAppA were modified according to the consensus sequence of two highly active Citrobacter phytases. One out of the eleven mutants, V89T, exhibited 17.5% increase in catalytic activity, which might be a result of stabilized protein folding. Second, the EcAppA glycosylation pattern was modified in accordance with the Citrobacter phytases. An N-glycosylation motif near the substrate binding site was disrupted to remove spatial hindrance for phytate entry and product departure. The de-glycosylated mutants showed 9.6% increase in specific activity. On the other hand, the EcAppA mutants that adopt N-glycosylation motifs from CbAppA showed improved thermostability that three mutants carrying single N-glycosylation motif exhibited 5.6-9.5% residual activity after treatment at 80°C (1.8% for wild type). Furthermore, the mutant carrying all three glycosylation motifs exhibited 27% residual activity. In conclusion, a successful rational design was performed to obtain several useful EcAppA mutants with better properties for further applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical engineering in the electronics industry: progress towards the rational design of organic semiconductor heterojunctions

KAUST Repository

Clancy, Paulette

2012-05-01

We review the current status of heterojunction design for combinations of organic semiconductor materials, given its central role in affecting the device performance for electronic devices and solar cell applications. We provide an emphasis on recent progress towards the rational design of heterojunctions that may lead to higher performance of charge separation and mobility. We also play particular attention to the role played by computational approaches and its potential to help define the best choice of materials for solar cell development in the future. We report the current status of the field with respect to such goals. © 2012 Elsevier Ltd.

Chemical engineering in the electronics industry: progress towards the rational design of organic semiconductor heterojunctions

KAUST Repository

Clancy, Paulette

2012-01-01

We review the current status of heterojunction design for combinations of organic semiconductor materials, given its central role in affecting the device performance for electronic devices and solar cell applications. We provide an emphasis on recent progress towards the rational design of heterojunctions that may lead to higher performance of charge separation and mobility. We also play particular attention to the role played by computational approaches and its potential to help define the best choice of materials for solar cell development in the future. We report the current status of the field with respect to such goals. © 2012 Elsevier Ltd.

Theory and simulation of DNA-coated colloids: a guide for rational design.

Science.gov (United States)

Angioletti-Uberti, Stefano; Mognetti, Bortolo M; Frenkel, Daan

2016-03-07

By exploiting the exquisite selectivity of DNA hybridization, DNA-coated colloids (DNACCs) can be made to self-assemble in a wide variety of structures. The beauty of this system stems largely from its exceptional versatility and from the fact that a proper choice of the grafted DNA sequences yields fine control over the colloidal interactions. Theory and simulations have an important role to play in the optimal design of self assembling DNACCs. At present, the powerful model-based design tools are not widely used, because the theoretical literature is fragmented and the connection between different theories is often not evident. In this Perspective, we aim to discuss the similarities and differences between the different models that have been described in the literature, their underlying assumptions, their strengths and their weaknesses. Using the tools described in the present Review, it should be possible to move towards a more rational design of novel self-assembling structures of DNACCs and, more generally, of systems where ligand-receptor are used to control interactions.

Rational In Silico Design of an Organic Semiconductor with Improved Electron Mobility.

Science.gov (United States)

Friederich, Pascal; Gómez, Verónica; Sprau, Christian; Meded, Velimir; Strunk, Timo; Jenne, Michael; Magri, Andrea; Symalla, Franz; Colsmann, Alexander; Ruben, Mario; Wenzel, Wolfgang

2017-11-01

Organic semiconductors find a wide range of applications, such as in organic light emitting diodes, organic solar cells, and organic field effect transistors. One of their most striking disadvantages in comparison to crystalline inorganic semiconductors is their low charge-carrier mobility, which manifests itself in major device constraints such as limited photoactive layer thicknesses. Trial-and-error attempts to increase charge-carrier mobility are impeded by the complex interplay of the molecular and electronic structure of the material with its morphology. Here, the viability of a multiscale simulation approach to rationally design materials with improved electron mobility is demonstrated. Starting from one of the most widely used electron conducting materials (Alq 3 ), novel organic semiconductors with tailored electronic properties are designed for which an improvement of the electron mobility by three orders of magnitude is predicted and experimentally confirmed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Curious Case of Fluorination of Conjugated Polymers for Solar Cells.

Science.gov (United States)

Zhang, Qianqian; Kelly, Mary Allison; Bauer, Nicole; You, Wei

2017-09-19

Organic solar cells (OSCs) have been a rising star in the field of renewable energy since the introduction of the bulk heterojunction (BHJ) in 1992. Recent advances have pushed the efficiencies of OSCs to over 13%, an impressive accomplishment via collaborative efforts in rational materials design and synthesis, careful device engineering, and fundamental understanding of device physics. Throughout these endeavors, several design principles for the conjugated donor polymers used in such solar cells have emerged, including optimizing the conjugated backbone with judicious selection of building blocks, side-chain engineering, and substituents. Among all of the substituents, fluorine is probably the most popular one; improved device characteristics with fluorination have frequently been reported for a wide range of conjugated polymers, in particular, donor-acceptor (D-A)-type polymers. Herein we examine the effect of fluorination on the device performance of solar cells as a function of the position of fluorination (on the acceptor unit or on the donor unit), aiming to outline a clear understanding of the benefits of this curious substituent. As fluorination of the acceptor unit is the most adopted strategy for D-A polymers, we first discuss the effect of fluorination of the acceptor units, highlighting the five most widely utilized acceptor units. While improved device efficiency has been widely observed with fluorinated acceptor units, the underlying reasons vary from case to case and highly depend on the chemical structure of the polymer. Second, the effect of fluorination of the donor unit is addressed. Here we focus on four donor units that have been most studied with fluorination. While device-performance-enhancing effects by fluorination of the donor units have also been observed, it is less clear that fluorine will always benefit the efficiency of the OSC, as there are several cases where the efficiency drops, in particular with "over-fluorination", i.e., when

Design of a Discrete Tracking Controller for a Magnetic Levitation System: A Nonlinear Rational Model Approach

Directory of Open Access Journals (Sweden)

Fernando Gómez-Salas

2015-01-01

Full Text Available This work proposes a discrete-time nonlinear rational approximate model for the unstable magnetic levitation system. Based on this model and as an application of the input-output linearization technique, a discrete-time tracking control design will be derived using the corresponding classical state space representation of the model. A simulation example illustrates the efficiency of the proposed methodology.

Rational design of a bi-layered reduced graphene oxide film on polystyrene foam for solar-driven interfacial water evaporation

KAUST Repository

Shi, Le; Wang, Yuchao; Zhang, Lianbin; Wang, Peng

2016-01-01

Solar-driven water evaporation has been emerging as a highly efficient way for utilizing solar energy for clean water production and wastewater treatment. Here we rationally designed and fabricated a bi-layered photothermal membrane with a porous

Rational Design, Synthesis and Pharmacological Evaluation of the (2R)- and (2S)-Stereoisomers of 3-(2-Carboxypyrrolidinyl)-2-methyl Acetic Acid as Ligands for the Ionotropic Glutamate Receptors

DEFF Research Database (Denmark)

Rasmussen, Julie; Storgaard, Morten; Pickering, Darryl S

2011-01-01

In this paper we describe the rational design, synthesis and pharmacological evaluation of two new stereoisomeric (S)-glutamate (Glu) analogues. The rational design was based on hybrid structures of the natural product kainic acid, a synthetic analogue CPAA and the high-affinity Glu analogue SYM...

Rational design of stealthy hyperuniform two-phase media with tunable order

Science.gov (United States)

DiStasio, Robert A.; Zhang, Ge; Stillinger, Frank H.; Torquato, Salvatore

2018-02-01

Disordered stealthy hyperuniform materials are exotic amorphous states of matter that have attracted recent attention because of their novel structural characteristics (hidden order at large length scales) and physical properties, including desirable photonic and transport properties. It is therefore useful to devise algorithms that enable one to design a wide class of such amorphous configurations at will. In this paper, we present several algorithms enabling the systematic identification and generation of discrete (digitized) stealthy hyperuniform patterns with a tunable degree of order, paving the way towards the rational design of disordered materials endowed with novel thermodynamic and physical properties. To quantify the degree of order or disorder of the stealthy systems, we utilize the discrete version of the τ order metric, which accounts for the underlying spatial correlations that exist across all relevant length scales in a given digitized two-phase (or, equivalently, a two-spin state) system of interest. Our results impinge on a myriad of fields, ranging from physics, materials science and engineering, visual perception, and information theory to modern data science.

Design and synthesis of a novel cationic thiolated polymer.

Science.gov (United States)

Rahmat, Deni; Sakloetsakun, Duangkamon; Shahnaz, Gul; Perera, Glen; Kaindl, Reinhard; Bernkop-Schnürch, Andreas

2011-06-15

The purpose of this study was to design and characterize a novel cationic thiolated polymer. In this regard a hydroxyethylcellulose-cysteamine conjugate (HEC-cysteamine) was synthesized. Oxidative ring opening with periodate and reductive amination with cysteamine were performed in order to immobilize free thiol groups to HEC. The resulting HEC-cysteamine displayed 2035 ± 162 μmol immobilized free thiol groups and 185 ± 64 μmol disulfide bonds per gram of polymer being soluble in both acidic and basic conditions. Unlike the unmodified HEC, in case of HEC-cysteamine, a three-fold increase in the viscosity was observed when equal volumes of the polymer were mixed with mucin solution. Tablets based on HEC-cysteamine remained attached on freshly excised porcine mucosa for 8 0h and displayed increased disintegration time of 2h. Swelling behavior of HEC-cysteamine tablets in 0.1M phosphate buffer pH 6.8 indicated swelling ratio of 19 within 8h. In contrast, tablets comprising unmodified HEC detached from the mucosa within few seconds and immediately disintegrated. In addition, they did not exhibit swelling behavior. The transport of rhodamine 123 across freshly excised rat intestine enhanced by a value of approximately 1.6-fold (p-value = 0.0024) in the presence of 0.5% (m/v) HEC-cysteamine as compared to buffer control. Result from cytotoxicity test of HEC-cysteamine applied to Caco-2 cells in concentration of 0.5% (m/v) revealed 82.4 ± 4.60% cell viability. According to these results, HEC-cysteamine seems to be a promising polymer for various pharmaceutical applications especially for intestinal drug delivery. Copyright © 2011. Published by Elsevier B.V.

Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

Energy Technology Data Exchange (ETDEWEB)

Farrington, Keith [School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Magner, Edmond [Materials and Surface Science Institute, Chemical and Environmental Sciences Department, University of Limerick, Limerick (Ireland); Regan, Fiona [School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland)]. E-mail: fiona.regan@dcu.ie

2006-04-27

A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound-caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform.

Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

International Nuclear Information System (INIS)

Farrington, Keith; Magner, Edmond; Regan, Fiona

2006-01-01

A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound-caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform

Computational molecular modeling and structural rationalization for the design of a drug-loaded PLLA/PVA biopolymeric membrane

International Nuclear Information System (INIS)

Sibeko, B; Pillay, V; Choonara, Y E; Khan, R A; Danckwerts, M P; Modi, G; Iyuke, S E; Naidoo, D

2009-01-01

The purpose of this study was to design, characterize and assess the influence of triethanolamine (TEA) on the physicomechanical properties and release of methotrexate (MTX) from a composite biopolymeric membrane. Conjugated poly(L-lactic acid) (PLLA) and poly(vinyl alcohol) (PVA) membranes were prepared by immersion precipitation with and without the addition of TEA. Drug entrapment efficiency (DEE) and release studies were performed in phosphate buffered saline (pH 7.4, 37 deg. C). Scanning electron microscopy elucidated the membrane surface morphology. Computational and structural molecular modeling rationalized the potential mechanisms of membrane formation and MTX release. Bi-axial force-distance (F-D) extensibility profiles were generated to determine the membrane toughness, elasticity and fracturability. Membranes were significantly toughened by the addition of TEA as a discrete rubbery phase within the co-polymer matrix. MTX-TEA-PLLA-PVA membranes were tougher (F = 89 N) and more extensible (D = 8.79 mm) compared to MTX-PLLA-PVA (F = 35 N, D = 3.7 mm) membranes as a greater force of extension and fracture distance were required (N = 10). DEE values were relatively high (>80%, N = 5) for both formulations. Photomicrographs revealed distinct crystalline layered morphologies with macro-pores. MTX was released by tri-phasic kinetics with a lower fractional release of MTX from MTX-TEA-PLLA-PVA membranes compared to MTX-PLLA-PVA. TEA provided a synergistic approach to improving the membrane physicomechanical properties and modulation of MTX release. The composite biopolymeric membrane may therefore be suitable for the novel delivery of MTX in the treatment of chronic primary central nervous system lymphoma.

Crystals of Human Serum Albumin for Use in Genetic Engineering and Rational Drug Design

Science.gov (United States)

Carter, Daniel C. (Inventor)

1994-01-01

This invention pertains to crystals of serum albumin and processes for growing them. The purpose of the invention is to provide crystals of serum albumin which can be studied to determine binding sites for drugs. Form 2 crystals grow in the monoclinic space P2(sub 1), and possesses the following unit cell constraints: a = 58.9 +/- 7, b = 88.3 +/- 7, c = 60.7 +/- 7, Beta = 101.0 +/- 2 degrees. One advantage of the invention is that it will allow rational drug design

Understanding and Design of Polymer Device Interfaces

Energy Technology Data Exchange (ETDEWEB)

Kahn, Antoine [Princeton Univ., NJ (United States)

2015-10-26

The research performed under grant DE-FG02-04ER46165 between May 2008 and April 2011 focused on the understanding and control of interfaces of organic semiconductors in general, and polymer interfaces more specifically. This work was a joined effort by three experimentalists and a theoretician. Emphasis was placed on the determination of the electronic structure of these interfaces, i.e. the relative energy position of molecular levels across these interfaces. From these electronic structures depend the injection, extraction and transport of charge carriers into, from and across, respectively, all (opto)electronic devices made of these semiconductors. A significant fraction of our work focused on ways to modify and optimize interfaces, for example via chemical doping of the semiconductors to reduce interface energy barriers or via deposition of ultra-thin work function-reducing polymer or self-assembled monolayers of dipolar molecules. Another significant fraction of our work was devoted to exploring alternate and unconventional interface formation methods, in particular the soft-contact lamination of both metal contacts and polymer overlayers on top of polymer films. These methods allowed us to better understand the impact of hot metal atom evaporation on a soft organic surface, as well as the key mechanisms that control the energetics of polymer/polymer heterojunctions. Finally, a significant fraction of the research was directed to understanding the electronic structure of buried polymer heterojunctions, in particular within donor/acceptor blends of interest in organic photovoltaic applications. The work supported by this grant resulted in 17 publications in some of the best peer-reviewed journals of the field, as well as numerous presentations at US and international conferences.

Rationalization: A Bibliography.

Science.gov (United States)

Pedrini, D. T.; Pedrini, Bonnie C.

Rationalization was studied by Sigmund Freud and was specifically labeled by Ernest Jones. Rationalization ought to be differentiated from rational, rationality, logical analysis, etc. On the one hand, rationalization is considered a defense mechanism, on the other hand, rationality is not. Haan has done much work with self-report inventories and…

Fluid Effects in Polymers and Polymeric Composites

CERN Document Server

Weitsman, Y Jack

2012-01-01

Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While...

Public policy, rationality and reason

Directory of Open Access Journals (Sweden)

Rodolfo Canto Sáenz

2015-07-01

Full Text Available This work suggests the incorporation of practical reason in the design, implementation and evaluation of public policies, alongside instrumental rationality. It takes two proposals that today point in this direction: Rawls distinction between reasonable (practical reason and rational (instrumental reason and what this author calls the CI Procedure (categorical imperative procedure and Habermas model of deliberative democracy. The main conclusion is that the analysis of public policies can not be limited to rather narrow limits of science, but requires the contribution of political and moral philosophy.

Rational Design and Synthesis of Efficient Sunscreens To Boost the Solar Protection Factor.

Science.gov (United States)

Losantos, Raúl; Funes-Ardoiz, Ignacio; Aguilera, José; Herrera-Ceballos, Enrique; García-Iriepa, Cristina; Campos, Pedro J; Sampedro, Diego

2017-03-01

Skin cancer incidence has been increasing in the last decades, but most of the commercial formulations used as sunscreens are designed to protect only against solar erythema. Many of the active components present in sunscreens show critical weaknesses, such as low stability and toxicity. Thus, the development of more efficient components is an urgent health necessity and an attractive industrial target. We have rationally designed core moieties with increased photoprotective capacities and a new energy dissipation mechanism. Using these scaffolds, we have synthesized a series of compounds with tunable properties suitable for their use in sunscreens, and enhanced properties in terms of stability, light energy dissipation, and toxicity. Moreover, some representative compounds were included in final sunscreen formulations and a relevant solar protection factor boost was measured. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Designer ligands: The search for metal ion selectivity

Directory of Open Access Journals (Sweden)

Perry T. Kaye

2011-03-01

Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

Rational Decision Making as Performative Praxis: Explaining Rationality's Éternel Retour

OpenAIRE

Cabantous, L.; Gond, J-P.

2011-01-01

Organizational theorists built their knowledge of decision making through a progressive critique of rational choice theory. Their positioning towards rationality, however, is at odds with the observation of rationality persistence in organizational life. This paper addresses this paradox. It proposes a new perspective on rationality that allows the theorizing of the production of rational decisions by organizations. To account for rationality's éternel retour, we approach rational decision ma...

Rational Design of a Green-Light-Mediated Unimolecular Platform for Fast Switchable Acidic Sensing.

Science.gov (United States)

Zhou, Yunyun; Zou, Qi; Qiu, Jing; Wang, Linjun; Zhu, Liangliang

2018-02-01

A controllable sensing ability strongly connects to complex and precise events in diagnosis and treatment. However, imposing visible light into the molecular-scale mediation of sensing processes is restricted by the lack of structural relevance. To address this critical challenge, we present the rational design, synthesis, and in vitro studies of a novel cyanostyryl-modified azulene system for green-light-mediated fast switchable acidic sensing. The advantageous features of the design include a highly efficient green-light-driven Z/E-isomerization (a quantum yield up to 61.3%) for fast erasing chromatic and luminescent expressions and a superior compatibility with control of ratiometric protonation. Significantly, these merits of the design enable the development of a microfluidic system to perform a green-light-mediated reusable sensing function toward a gastric acid analyte in a miniaturized platform. The results may provide new insights for building future integrated green materials.

Molecular Design, Structures, and Activity of Antimicrobial Peptide-Mimetic Polymers

Science.gov (United States)

Takahashi, Haruko; Palermo, Edmund F.; Yasuhara, Kazuma; Caputo, Gregory A.

2014-01-01

There is an urgent need for new antibiotics which are effective against drug-resistant bacteria without contributing to resistance development. We have designed and developed antimicrobial copolymers with cationic amphiphilic structures based on the mimicry of naturally occurring antimicrobial peptides. These copolymers exhibit potent antimicrobial activity against a broad spectrum of bacteria including methicillin-resistant Staphylococcus aureus with no adverse hemolytic activity. Notably, these polymers also did not result in any measurable resistance development in E. coli. The peptide-mimetic design principle offers significant flexibility and diversity in the creation of new antimicrobial materials and their potential biomedical applications. PMID:23832766

Morphology control in polymer blend fibers—a high throughput computing approach

Science.gov (United States)

Sesha Sarath Pokuri, Balaji; Ganapathysubramanian, Baskar

2016-08-01

Fibers made from polymer blends have conventionally enjoyed wide use, particularly in textiles. This wide applicability is primarily aided by the ease of manufacturing such fibers. More recently, the ability to tailor the internal morphology of polymer blend fibers by carefully designing processing conditions has enabled such fibers to be used in technologically relevant applications. Some examples include anisotropic insulating properties for heat and anisotropic wicking of moisture, coaxial morphologies for optical applications as well as fibers with high internal surface area for filtration and catalysis applications. However, identifying the appropriate processing conditions from the large space of possibilities using conventional trial-and-error approaches is a tedious and resource-intensive process. Here, we illustrate a high throughput computational approach to rapidly explore and characterize how processing conditions (specifically blend ratio and evaporation rates) affect the internal morphology of polymer blends during solvent based fabrication. We focus on a PS: PMMA system and identify two distinct classes of morphologies formed due to variations in the processing conditions. We subsequently map the processing conditions to the morphology class, thus constructing a ‘phase diagram’ that enables rapid identification of processing parameters for specific morphology class. We finally demonstrate the potential for time dependent processing conditions to get desired features of the morphology. This opens up the possibility of rational stage-wise design of processing pathways for tailored fiber morphology using high throughput computing.

Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

Science.gov (United States)

Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

2009-01-01

The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.

Photoinduced charge and energy transfer in dye-doped conjugated polymers

International Nuclear Information System (INIS)

Veldman, Dirk; Bastiaansen, Jolanda J.A.M.; Langeveld-Voss, Bea M.W.; Sweelssen, Joergen; Koetse, Marc M.; Meskers, Stefan C.J.; Janssen, Rene A.J.

2006-01-01

Conjugated polymer-molecular dye blends of MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]) and PF1CVTP (poly[9,9-dioctylfluorene-2,7-diyl-alt-2,5-bis(2-thienyl-1-cyanovinyl) -1-(3',7= '-dimethyloctyloxy)-4-methoxybenzene-5'',5''-diyl]) with three dipyrrometheneboron difluoride (bodipy) dyes were studied by (time-resolved) fluorescence and photoinduced absorption spectroscopy to determine quantitatively the relation between the electronic HOMO and LUMO levels and the occurrence of energy or charge transfer after optical excitation. We find that for MDMO-PPV photoinduced charge transfer to the dyes occurs, while photoexcitation of PF1CVTP exclusively results in energy transfer. The differences can be rationalized by assuming that the energy of the charge separated state is 0.33-0.45 eV higher than the energy determined from oxidation and reduction potentials of donor and acceptor, respectively. This provides an important design rule to identify appropriate materials for polymer solar cells that can have a high open-circuit voltage

Rational design of carbon and TiO2 assembly materials: covered or strewn, which is better for photocatalysis?

Science.gov (United States)

Cui, Guan-wei; Wang, Wei-liang; Ma, Ming-yue; Zhang, Ming; Xia, Xin-yuan; Han, Feng-yun; Shi, Xi-feng; Zhao, Ying-qiang; Dong, Yu-bin; Tang, Bo

2013-07-21

The rational design of carbonaceous hybrid nanostructures is very important for obtaining high photoactivity. TiO2 particles strewn with an optimal quantity of carbon nanodots have a much higher photoactivity than that of TiO2 covered with a carbon layer, showing the importance of carbon morphology in the photocatalysis of carbonaceous hybrid nanostructures.

Design of water-soluble, thiol-reactive polymers of controlled molecular weight: a novel multivalent scaffold

Science.gov (United States)

Carrillo, Alvaro; Gujraty, Kunal V.; Rai, Prakash R.; Kane, Ravi S.

2005-07-01

Multivalent molecules, i.e. scaffolds presenting multiple copies of a suitable ligand, constitute an emerging class of nanoscale therapeutics. We present a novel approach for the design of multivalent ligands, which allows the biofunctionalization of polymers with proteins or peptides in a controlled orientation. It consists of the synthesis of water-soluble, activated polymer scaffolds of controlled molecular weight, which can be biofunctionalized with various thiolated ligands in aqueous media under mild conditions. These polymers were synthesized by ring-opening metathesis polymerization (ROMP) and further modified to make them water-soluble. The incorporation of chloride groups activated the polymers to react with thiol-containing peptides or proteins, and the formation of multivalent ligands in aqueous media was demonstrated. This strategy represents a convenient route for synthesizing multivalent ligands of controlled dimensions and valency.

Laccase engineering: from rational design to directed evolution.

Science.gov (United States)

Mate, Diana M; Alcalde, Miguel

2015-01-01

Laccases are multicopper oxidoreductases considered by many in the biotechonology field as the ultimate "green catalysts". This is mainly due to their broad substrate specificity and relative autonomy (they use molecular oxygen from air as an electron acceptor and they only produce water as by-product), making them suitable for a wide array of applications: biofuel production, bioremediation, organic synthesis, pulp biobleaching, textiles, the beverage and food industries, biosensor and biofuel cell development. Since the beginning of the 21st century, specific features of bacterial and fungal laccases have been exhaustively adapted in order to reach the industrial demands for high catalytic activity and stability in conjunction with reduced production cost. Among the goals established for laccase engineering, heterologous functional expression, improved activity and thermostability, tolerance to non-natural media (organic solvents, ionic liquids, physiological fluids) and resistance to different types of inhibitors are all challenges that have been met, while obtaining a more comprehensive understanding of laccase structure-function relationships. In this review we examine the most significant advances in this exciting research area in which rational, semi-rational and directed evolution approaches have been employed to ultimately convert laccases into high value-added biocatalysts. Copyright © 2014 Elsevier Inc. All rights reserved.

Matrix Organization and Merit Factor Evaluation as a Method to Address the Challenge of Finding a Polymer Material for Roll Coated Polymer Solar Cells

DEFF Research Database (Denmark)

Bundgaard, Eva; Livi, Francesco; Hagemann, Ole

2015-01-01

The results presented demonstrate how the screening of 104 light-absorbing low band gap polymers for suitability in roll coated polymer solar cells can be accomplished through rational synthesis according to a matrix where 8 donor and 13 acceptor units are organized in rows and columns. Synthesis...... silver comb back electrode structure. The matrix organization enables fast identification of active layer materials according to a weighted merit factor that includes more than simply the power conversion efficiency and is used as a method to identify the lead candidates. Based on several characteristics...

Molecular Design for Preparation of Hexagonal-Ordered Porous Films Based on Side-chain Type Liquid-Crystalline Star Polymer.

Science.gov (United States)

Naka, Yumiko; Takayama, Hiromu; Koyama, Teruhisa; Le, Khoa V; Sasaki, Takeo

2018-05-02

Fabrication of regularly porous films by the breath-figure method has attracted much attention. The simple, low-cost technique uses the condensation of water droplets to produce these structures, but the phenomenon itself is complex, requiring control over many interacting parameters that change throughout the process. Developing a unified understanding for the molecular design of polymers to prepare ordered porous films is challenging, but required for further advancements. In this article, the effects of the chemical structure of polymers in the breath-figure technique were systematically explored using side-chain type liquid-crystalline (LC) star polymers. The formation of porous films was affected by the structure of the polymers. Although the entire film surface of poly(11-[4-(4-cyanobiphenyl)oxy]undecyl methacrylate) (P11CB) had a hexagonal ordered porous structure over a certain Mn value, regularly arranged holes did not easily form in poly(methyl methacrylate) (PMMA), even though the main chain of PMMA is similar to that of P11CB. Comparing P11CB and poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11B) (P11CB without cyano groups) showed that the local polar groups in hydrophobic polymers promoted the formation of ordered porous films. No holes formed in poly(4-cyanobiphenyl methacrylate) (P0CB) (P11CB without alkyl spacers) films due to its hydrophilicity. The introduction of alkyl chains in P0CB allowed the preparation of honeycomb-structured films by increasing the internal tension. However, alkyl chains in the side chain alone did not result in a porous structure, as in the case of poly(11-[(1,1'-biphenyl)-4-yloxy]undecyl methacrylate) (P11). Aromatic rings are also required to increase the Tg and improve film formability. In the present study, suitable molecular designs of polymers were found, specifically hydrophobic polymers with local polar groups, to form a regularly porous structure. Development of clear guidelines for the molecular

Design of polymer networks by variation of precursor structure and crosslinking regime

Czech Academy of Sciences Publication Activity Database

Dušek, Karel; Dušková, Miroslava; Huybrecht, J.

2003-01-01

Roč. 44, č. 1 (2003), s. 62-63 ISSN 0032-3934. [ACS National Meeting "Crosslinking Materials and Processes"/254./. New Orleans, 23.03.2003-27.03.2003] R&D Projects: GA AV ČR KSK4050111 Keywords : polymer networks * designed precursor * crosslinking Subject RIV: CD - Macromolecular Chemistry

Rationality in Society

NARCIS (Netherlands)

Flache, Andreas; Dijkstra, Jacob; Wright, James D.

2015-01-01

Contemporary theories of rational behavior in human society augment the orthodox model of rationality both by adding various forms of bounded rationality and relaxing the assumptions of self-interest and materialistic preferences. This entry discusses how these extensions of the theory of rational

Computational approaches in the design of synthetic receptors – A review

Energy Technology Data Exchange (ETDEWEB)

Cowen, Todd, E-mail: tc203@le.ac.uk; Karim, Kal; Piletsky, Sergey

2016-09-14

The rational design of molecularly imprinted polymers (MIPs) has been a major contributor to their reputation as “plastic antibodies” – high affinity robust synthetic receptors which can be optimally designed, and produced for a much reduced cost than their biological equivalents. Computational design has become a routine procedure in the production of MIPs, and has led to major advances in functional monomer screening, selection of cross-linker and solvent, optimisation of monomer(s)-template ratio and selectivity analysis. In this review the various computational methods will be discussed with reference to all the published relevant literature since the end of 2013, with each article described by the target molecule, the computational approach applied (whether molecular mechanics/molecular dynamics, semi-empirical quantum mechanics, ab initio quantum mechanics (Hartree-Fock, Møller–Plesset, etc.) or DFT) and the purpose for which they were used. Detailed analysis is given to novel techniques including analysis of polymer binding sites, the use of novel screening programs and simulations of MIP polymerisation reaction. The further advances in molecular modelling and computational design of synthetic receptors in particular will have serious impact on the future of nanotechnology and biotechnology, permitting the further translation of MIPs into the realms of analytics and medical technology. - Highlights: • A review of computational modelling in the design of molecularly imprinted polymers. • Target analytes and method of analysis for the vast majority of recent articles. • Explanations are given of all the popular and emerging techniques used in design. • Highlighted examples of sophisticated analysis of imprinted polymer systems.

Computational approaches in the design of synthetic receptors – A review

International Nuclear Information System (INIS)

Cowen, Todd; Karim, Kal; Piletsky, Sergey

2016-01-01

The rational design of molecularly imprinted polymers (MIPs) has been a major contributor to their reputation as “plastic antibodies” – high affinity robust synthetic receptors which can be optimally designed, and produced for a much reduced cost than their biological equivalents. Computational design has become a routine procedure in the production of MIPs, and has led to major advances in functional monomer screening, selection of cross-linker and solvent, optimisation of monomer(s)-template ratio and selectivity analysis. In this review the various computational methods will be discussed with reference to all the published relevant literature since the end of 2013, with each article described by the target molecule, the computational approach applied (whether molecular mechanics/molecular dynamics, semi-empirical quantum mechanics, ab initio quantum mechanics (Hartree-Fock, Møller–Plesset, etc.) or DFT) and the purpose for which they were used. Detailed analysis is given to novel techniques including analysis of polymer binding sites, the use of novel screening programs and simulations of MIP polymerisation reaction. The further advances in molecular modelling and computational design of synthetic receptors in particular will have serious impact on the future of nanotechnology and biotechnology, permitting the further translation of MIPs into the realms of analytics and medical technology. - Highlights: • A review of computational modelling in the design of molecularly imprinted polymers. • Target analytes and method of analysis for the vast majority of recent articles. • Explanations are given of all the popular and emerging techniques used in design. • Highlighted examples of sophisticated analysis of imprinted polymer systems.

A Rational Approach to Rational Suicide.

Science.gov (United States)

Richman, Joseph

1992-01-01

Describes suicide as reaction to internal and external sources of stress and the impact of life events. Notes that, in the elderly, these situations are prevalent in many who are not suicidal. Contends that much more is written about rational suicide than its alternative (rational nonsuicide). Reviews reasons for this and suggests rational…

Rational design of competitive electrocatalysts for the oxygen reduction reaction in hydrogen fuel cells

Science.gov (United States)

Stolbov, Sergey; Alcántara Ortigoza, Marisol

2012-02-01

The large-scale application of one of the most promising clean and renewable sources of energy, hydrogen fuel cells, still awaits efficient and cost-effective electrocatalysts for the oxygen reduction reaction (ORR) occurring on the cathode. We demonstrate that truly rational design renders electrocatalysts possessing both qualities. By unifying the knowledge on surface morphology, composition, electronic structure and reactivity, we solve that sandwich-like structures are an excellent choice for optimization. Their constituting species couple synergistically yielding reaction-environment stability, cost-effectiveness and tunable reactivity. This cooperative-action concept enabled us to predict two advantageous ORR electrocatalysts. Density functional theory calculations of the reaction free-energy diagrams confirm that these materials are more active toward ORR than the so far best Pt-based catalysts. Our designing concept advances also a general approach for engineering materials in heterogeneous catalysis.

Control of charge carrier dynamics in disordered conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Hertel, Dirk [Physical Chemistry, University of Cologne, Luxemburgerstr. 116, 50939 Cologne, Germany, (Germany)

2011-07-01

We developed a new method to probe charge carrier mobility on ultrafast time scale. It is based on electric field induced second harmonic generation. The method is applied to prototypical amorphous conjugated polymers of the polyphenylene- and polyfluorene-type. Typically the carrier mobility in these organic polymers decreases with time in a power law fashion from about 1 cm{sup 2}Vs{sup -1} at 1 ps to its stationary value of about 10{sup -6} cm{sup 2}Vs{sup -1} in hundreds of ns. The dynamics of the mobility is discussed. It is shown, that in nanoscale devices the macroscopic mobility is not adequate to describe charge transport. We study the influence of disorder, morphology and temperature on ultrafast transport. At early times the transport is dominated by tunneling and disorder plays already an essential role. Comparison of transient photocurrents with Monte-Carlo simulation reveals that on-chain transport has to be invoked to rationalize our results. The hopping rates for intrachain transport are much larger compared with interchain transport. The results give access to essential transport properties for the development of advanced theoretical models and may help to design improved solar cells.

Geometric Rationalization for Freeform Architecture

KAUST Repository

Jiang, Caigui

2016-06-20

The emergence of freeform architecture provides interesting geometric challenges with regards to the design and manufacturing of large-scale structures. To design these architectural structures, we have to consider two types of constraints. First, aesthetic constraints are important because the buildings have to be visually impressive. Sec- ond, functional constraints are important for the performance of a building and its e cient construction. This thesis contributes to the area of architectural geometry. Specifically, we are interested in the geometric rationalization of freeform architec- ture with the goal of combining aesthetic and functional constraints and construction requirements. Aesthetic requirements typically come from designers and architects. To obtain visually pleasing structures, they favor smoothness of the building shape, but also smoothness of the visible patterns on the surface. Functional requirements typically come from the engineers involved in the construction process. For exam- ple, covering freeform structures using planar panels is much cheaper than using non-planar ones. Further, constructed buildings have to be stable and should not collapse. In this thesis, we explore the geometric rationalization of freeform archi- tecture using four specific example problems inspired by real life applications. We achieve our results by developing optimization algorithms and a theoretical study of the underlying geometrical structure of the problems. The four example problems are the following: (1) The design of shading and lighting systems which are torsion-free structures with planar beams based on quad meshes. They satisfy the functionality requirements of preventing light from going inside a building as shad- ing systems or reflecting light into a building as lighting systems. (2) The Design of freeform honeycomb structures that are constructed based on hex-dominant meshes with a planar beam mounted along each edge. The beams intersect without

Understanding the origins of metal-organic framework/polymer compatibility.

Science.gov (United States)

Semino, R; Moreton, J C; Ramsahye, N A; Cohen, S M; Maurin, G

2018-01-14

The microscopic interfacial structures for a series of metal-organic framework/polymer composites consisting of the Zr-based UiO-66 coupled with different polymers are systematically explored by applying a computational methodology that integrates density functional theory calculations and force field-based molecular dynamics simulations. These predictions are correlated with experimental findings to unravel the structure-compatibility relationship of the MOF/polymer pairs. The relative contributions of the intermolecular MOF/polymer interactions and the flexibility/rigidity of the polymer with respect to the microscopic structure of the interface are rationalized, and their impact on the compatibility of the two components in the resulting composite is discussed. The most compatible pairs among those investigated involve more flexible polymers, i.e. polyvinylidene fluoride (PVDF) and polyethylene glycol (PEG). These polymers exhibit an enhanced contact surface, due to a better adaptation of their configuration to the MOF surface. In these cases, the irregularities at the MOF surface are filled by the polymer, and even some penetration of the terminal groups of the polymer into the pores of the MOF can be observed. As a result, the affinity between the MOF and the polymer is very high; however, the pores of the MOF may be sterically blocked due to the strong MOF/polymer interactions, as evidenced by UiO-66/PEG composites. In contrast, composites involving polymers that exhibit higher rigidity, such as the polymer of intrinsic microporosity-1 (PIM-1) or polystyrene (PS), present interfacial microvoids that contribute to a decrease in the contact surface between the two components, thus reducing the MOF/polymer affinity.

Molecular designing of novel ternary copolymers of donor-acceptor polymers using genetic algorithm

International Nuclear Information System (INIS)

Arora, Vinita; Bakhshi, A.K.

2010-01-01

Graphical abstract: Alternate arrangement of donor acceptor moieties in the carbon backbone chain of an organic conjugated polymer is capable of inducing charge transfer and affects the electronic properties of the copolymer. Genetic algorithm along with simple NFC (negative factor counting) and IIM (inverse iteration method) has been used to optimize the properties of novel ternary copolymers based on polypyrrole PPy, polythiophene PTh and polyfuran PFu (as donor moieties) and containing >C=O and >C=CF 2 bridging units as acceptor moieties. - Abstract: An efficient designing route to novel ternary copolymers consisting of polypyrrole (PPy), polythiophene (PTh) and polyfuran (PFu) is developed with the help of genetic algorithm. Using the band structure results obtained from ab initio crystal orbital (CO) calculations, the electronic structures and conduction properties of real ternary copolymers based on donor acceptor type polymers are investigated. The electron rich heterocyclic rings in the backbone chain of the copolymer are joined together by electron withdrawing groups Y, carbonyl group (>C=O) and difluoromethylene group (>C=CF 2 ) in an attempt to design the conducting polymer with lowest band gap. A comparative study of various electronic properties is presented. The effects of substitution on the behaviour and properties of the copolymers as well as on the density of states (DOS) are discussed. Band gap decreases as a result of substitution on the polymer backbone chain due to decrease in ionization potential and increase in electron affinity values. This is expected to enhance the intrinsic conductivity of the resulting copolymer. Use of alternate donor acceptor moieties within the repeat units should maximize the extended π conjugation.

Molecular designing of novel ternary copolymers of donor-acceptor polymers using genetic algorithm

Energy Technology Data Exchange (ETDEWEB)

Arora, Vinita [Department of Chemistry, University of Delhi, Delhi 110 007 (India); Bakhshi, A.K., E-mail: akbakhshi2000@yahoo.com [Department of Chemistry, University of Delhi, Delhi 110 007 (India)

2010-08-03

Graphical abstract: Alternate arrangement of donor acceptor moieties in the carbon backbone chain of an organic conjugated polymer is capable of inducing charge transfer and affects the electronic properties of the copolymer. Genetic algorithm along with simple NFC (negative factor counting) and IIM (inverse iteration method) has been used to optimize the properties of novel ternary copolymers based on polypyrrole PPy, polythiophene PTh and polyfuran PFu (as donor moieties) and containing >C=O and >C=CF{sub 2} bridging units as acceptor moieties. - Abstract: An efficient designing route to novel ternary copolymers consisting of polypyrrole (PPy), polythiophene (PTh) and polyfuran (PFu) is developed with the help of genetic algorithm. Using the band structure results obtained from ab initio crystal orbital (CO) calculations, the electronic structures and conduction properties of real ternary copolymers based on donor acceptor type polymers are investigated. The electron rich heterocyclic rings in the backbone chain of the copolymer are joined together by electron withdrawing groups Y, carbonyl group (>C=O) and difluoromethylene group (>C=CF{sub 2}) in an attempt to design the conducting polymer with lowest band gap. A comparative study of various electronic properties is presented. The effects of substitution on the behaviour and properties of the copolymers as well as on the density of states (DOS) are discussed. Band gap decreases as a result of substitution on the polymer backbone chain due to decrease in ionization potential and increase in electron affinity values. This is expected to enhance the intrinsic conductivity of the resulting copolymer. Use of alternate donor acceptor moieties within the repeat units should maximize the extended {pi} conjugation.

A rationally designed composite of alternating strata of Si nanoparticles and graphene: a high-performance lithium-ion battery anode.

Science.gov (United States)

Sun, Fu; Huang, Kai; Qi, Xiang; Gao, Tian; Liu, Yuping; Zou, Xianghua; Wei, Xiaolin; Zhong, Jianxin

2013-09-21

We have successfully fabricated a free-standing Si-re-G (reduced graphene) alternating stratum structure composite through a repeated process of filtering liquid exfoliated graphene oxide and uniformly dispersed Si solution, followed by the reduction of graphene oxide. The as-prepared free-standing flexible alternating stratum structure composite was directly evaluated as the anode for rechargeable lithium half-cells without adding any polymer binder, conductive additives or using current collectors. The half cells based on this new alternating structure composite exhibit an unexpected capacity of 1500 mA h g(-1) after 100 cycles at 1.35 A g(-1). Our rationally proposed strategy has incorporated the long cycle life of carbon and the high lithium-storage capacity of Si into one entity using the feasible and scalable vacuum filtration technique, rendering this new protocol as a readily applicable means of addressing the practical application challenges associated with the next generation of rechargeable lithium-ion batteries.

Guidelines for Rational Cancer Therapeutics

Directory of Open Access Journals (Sweden)

Byunghee Yoo

2017-12-01

Full Text Available Traditionally, cancer therapy has relied on surgery, radiation therapy, and chemotherapy. In recent years, these interventions have become increasingly replaced or complemented by more targeted approaches that are informed by a deeper understanding of the underlying biology. Still, the implementation of fully rational patient-specific drug design appears to be years away. Here, we present a vision of rational drug design for cancer that is defined by two major components: modularity and image guidance. We suggest that modularity can be achieved by combining a nanocarrier and an oligonucleotide component into the therapeutic. Image guidance can be incorporated into the nanocarrier component by labeling with a specific imaging reporter, such as a radionuclide or contrast agent for magnetic resonance imaging. While limited by the need for additional technological advancement in the areas of cancer biology, nanotechnology, and imaging, this vision for the future of cancer therapy can be used as a guide to future research endeavors.

Rational design of DNA sequences for nanotechnology, microarrays and molecular computers using Eulerian graphs.

Science.gov (United States)

Pancoska, Petr; Moravek, Zdenek; Moll, Ute M

2004-01-01

Nucleic acids are molecules of choice for both established and emerging nanoscale technologies. These technologies benefit from large functional densities of 'DNA processing elements' that can be readily manufactured. To achieve the desired functionality, polynucleotide sequences are currently designed by a process that involves tedious and laborious filtering of potential candidates against a series of requirements and parameters. Here, we present a complete novel methodology for the rapid rational design of large sets of DNA sequences. This method allows for the direct implementation of very complex and detailed requirements for the generated sequences, thus avoiding 'brute force' filtering. At the same time, these sequences have narrow distributions of melting temperatures. The molecular part of the design process can be done without computer assistance, using an efficient 'human engineering' approach by drawing a single blueprint graph that represents all generated sequences. Moreover, the method eliminates the necessity for extensive thermodynamic calculations. Melting temperature can be calculated only once (or not at all). In addition, the isostability of the sequences is independent of the selection of a particular set of thermodynamic parameters. Applications are presented for DNA sequence designs for microarrays, universal microarray zip sequences and electron transfer experiments.

Passive control of quorum sensing: prevention of Pseudomonas aeruginosa biofilm formation by imprinted polymers.

Science.gov (United States)

Piletska, Elena V; Stavroulakis, Georgios; Larcombe, Lee D; Whitcombe, Michael J; Sharma, Anant; Primrose, Sandy; Robinson, Gary K; Piletsky, Sergey A

2011-04-11

Here we present the first molecular imprinted polymer (MIP) that is able to attenuate the biofilm formation of the opportunistic human pathogen Pseudomonas aeruginosa through specific sequestration of its signal molecule N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C(12)-AHL). The MIP was rationally designed using computational modeling, and its capacity and specificity and that of a corresponding blank polymer toward signal molecule of P. aeruginosa (3-oxo-C(12)-AHL) and its analogue were tested. The biofilm formation in the presence of polymers and without polymers was studied using scanning confocal laser microscopy. Staining with crystal violet dye was used for the quantification of the biofilm formation. A significant reduction of the biofilm growth was observed in the presence of MIP (>80%), which was superior to that of the resin prepared without template, which showed a reduction of 40% in comparison with biofilm, which was grown without polymer addition. It was shown that 3-oxo-C(12)-AHL-specific MIP prevented the development of quorum-sensing-controlled phenotypes (in this case, biofilm formation) from being up-regulated. The developed MIP could be considered as a new tool for the elimination of life-threatening infections in a multitude of practical applications; it could, for example, be grafted on the surface of medical devices such as catheters and lenses, be a component of paints, or be used as a wound adsorbent.

The Effect of Covalently-Attached ATRP-Synthesized Polymers on Membrane Stability and Cytoprotection in Human Erythrocytes.

Science.gov (United States)

Clafshenkel, William P; Murata, Hironobu; Andersen, Jill; Creeger, Yehuda; Koepsel, Richard R; Russell, Alan J

2016-01-01

Erythrocytes have been described as advantageous drug delivery vehicles. In order to ensure an adequate circulation half-life, erythrocytes may benefit from protective enhancements that maintain membrane integrity and neutralize oxidative damage of membrane proteins that otherwise facilitate their premature clearance from circulation. Surface modification of erythrocytes using rationally designed polymers, synthesized via atom-transfer radical polymerization (ATRP), may further expand the field of membrane-engineered red blood cells. This study describes the fate of ATRP-synthesized polymers that were covalently attached to human erythrocytes as well as the effect of membrane engineering on cell stability under physiological and oxidative conditions in vitro. The biocompatible, membrane-reactive polymers were homogenously retained on the periphery of modified erythrocytes for at least 24 hours. Membrane engineering stabilized the erythrocyte membrane and effectively neutralized oxidative species, even in the absence of free-radical scavenger-containing polymers. The targeted functionalization of Band 3 protein by NHS-pDMAA-Cy3 polymers stabilized its monomeric form preventing aggregation in the presence of the crosslinking reagent, bis(sulfosuccinimidyl)suberate (BS3). A free radical scavenging polymer, NHS-pDMAA-TEMPO˙, provided additional protection of surface modified erythrocytes in an in vitro model of oxidative stress. Preserving or augmenting cytoprotective mechanisms that extend circulation half-life is an important consideration for the use of red blood cells for drug delivery in various pathologies, as they are likely to encounter areas of imbalanced oxidative stress as they circuit the vascular system.

The Effect of Covalently-Attached ATRP-Synthesized Polymers on Membrane Stability and Cytoprotection in Human Erythrocytes.

Directory of Open Access Journals (Sweden)

William P Clafshenkel

Full Text Available Erythrocytes have been described as advantageous drug delivery vehicles. In order to ensure an adequate circulation half-life, erythrocytes may benefit from protective enhancements that maintain membrane integrity and neutralize oxidative damage of membrane proteins that otherwise facilitate their premature clearance from circulation. Surface modification of erythrocytes using rationally designed polymers, synthesized via atom-transfer radical polymerization (ATRP, may further expand the field of membrane-engineered red blood cells. This study describes the fate of ATRP-synthesized polymers that were covalently attached to human erythrocytes as well as the effect of membrane engineering on cell stability under physiological and oxidative conditions in vitro. The biocompatible, membrane-reactive polymers were homogenously retained on the periphery of modified erythrocytes for at least 24 hours. Membrane engineering stabilized the erythrocyte membrane and effectively neutralized oxidative species, even in the absence of free-radical scavenger-containing polymers. The targeted functionalization of Band 3 protein by NHS-pDMAA-Cy3 polymers stabilized its monomeric form preventing aggregation in the presence of the crosslinking reagent, bis(sulfosuccinimidylsuberate (BS3. A free radical scavenging polymer, NHS-pDMAA-TEMPO˙, provided additional protection of surface modified erythrocytes in an in vitro model of oxidative stress. Preserving or augmenting cytoprotective mechanisms that extend circulation half-life is an important consideration for the use of red blood cells for drug delivery in various pathologies, as they are likely to encounter areas of imbalanced oxidative stress as they circuit the vascular system.

A rational and economical seismic design of beam columns in steel frames

International Nuclear Information System (INIS)

Gupta, A.K.; Fang, S.-J.; Chu, S.-L.

1977-01-01

In the present study, a new rational procedure is used in which simultaneous variation in various response quantities is predicted. For designing the beam column section according to the AISC Manual of Steel Construction, one has to know the values of the axial force, the moment about x and y axes at the two ends, and the maximum moments about x, y axes near the center of the beam column, which altogether constitutes seven response quantities of interest for each beam column element. Normally, seven equivalent modes will be required to represent the response. However, by designing the two end sections and the intermediate section independently one can consider three equivalent modes for each section, thus simplifying the problem a great deal. An existing computer program is used for the implementation of the proposed method. Results for typical example problems have been presented. It is shown that savings up to 42% in the steel cross-sectional area can be obtained depending upon combination of various forces and moments. The propposed method is 'exact' within the existing assumptions of the SRSS (square root of the sum of the squares) or the double sum method

Rational design of botulinum neurotoxin A1 mutants with improved oxidative stability.

Science.gov (United States)

López de la Paz, Manuela; Scheps, Daniel; Jurk, Marcel; Hofmann, Fred; Frevert, Jürgen

2018-06-01

Botulinum neurotoxins (BoNTs) are the most potent toxic proteins to mankind known but applied in low doses trigger a localized muscle paralysis that is beneficial for the therapy of several neurological disorders and aesthetic treatment. The paralytic effect is generated by the enzymatic activity of the light chain (LC) that cleaves specifically one of the SNARE proteins responsible for neurotransmitter exocytosis. The activity of the LC in a BoNT-containing therapeutic can be compromised by denaturing agents present during manufacturing and/or in the cell. Stabilization of the LC by reducing vulnerability towards denaturants would thus be advantageous for the development of BoNT-based therapeutics. In this work, we focused on increasing the stability of LC of BoNT/A1 (LC/A1) towards oxidative stress. We tackled this task by rational design of mutations at cysteine and methionine LC/A1 sites. Designed mutants showed improved oxidative stability in vitro and equipotency to wildtype toxin in vivo. Our results suggest that suitable modification of the catalytic domain can lead to more stable BoNTs without impairing their therapeutic efficacy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Model-based rational feedback controller design for closed-loop deep brain stimulation of Parkinson's disease

Science.gov (United States)

Gorzelic, P.; Schiff, S. J.; Sinha, A.

2013-04-01

Objective. To explore the use of classical feedback control methods to achieve an improved deep brain stimulation (DBS) algorithm for application to Parkinson's disease (PD). Approach. A computational model of PD dynamics was employed to develop model-based rational feedback controller design. The restoration of thalamocortical relay capabilities to patients suffering from PD is formulated as a feedback control problem with the DBS waveform serving as the control input. Two high-level control strategies are tested: one that is driven by an online estimate of thalamic reliability, and another that acts to eliminate substantial decreases in the inhibition from the globus pallidus interna (GPi) to the thalamus. Control laws inspired by traditional proportional-integral-derivative (PID) methodology are prescribed for each strategy and simulated on this computational model of the basal ganglia network. Main Results. For control based upon thalamic reliability, a strategy of frequency proportional control with proportional bias delivered the optimal control achieved for a given energy expenditure. In comparison, control based upon synaptic inhibitory output from the GPi performed very well in comparison with those of reliability-based control, with considerable further reduction in energy expenditure relative to that of open-loop DBS. The best controller performance was amplitude proportional with derivative control and integral bias, which is full PID control. We demonstrated how optimizing the three components of PID control is feasible in this setting, although the complexity of these optimization functions argues for adaptive methods in implementation. Significance. Our findings point to the potential value of model-based rational design of feedback controllers for Parkinson's disease.

Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

Science.gov (United States)

Li, Qi; Liu, Feihua; Yang, Tiannan; Gadinski, Matthew R.; Zhang, Guangzu; Chen, Long-Qing; Wang, Qing

2016-01-01

The demand for a new generation of high-temperature dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite-based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high-temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single-layer configuration, the rationally designed sandwich-structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge–discharge efficiency at elevated temperatures. At 150 °C and 200 MV m−1, an operating condition toward electric vehicle applications, the sandwich-structured polymer nanocomposites outperform the state-of-the-art polymer-based dielectrics in terms of energy density, power density, charge–discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present. PMID:27551101

Rational design of peptide affinity ligands for the purification of therapeutic enzymes.

Science.gov (United States)

Trasatti, John P; Woo, James; Ladiwala, Asif; Cramer, Steven; Karande, Pankaj

2018-04-25

Non-mAb biologics represent a growing class of therapeutics under clinical development. Although affinity chromatography is a potentially attractive approach for purification, the development of platform technologies, such as Protein A for mAbs, has been challenging due to the inherent chemical and structural diversity of these molecules. Here, we present our studies on the rapid development of peptide affinity ligands for the purification of biologics using a prototypical enzyme therapeutic in clinical use. Employing a suite of de novo rational and combinatorial design strategies we designed and screened a library of peptides on microarray platforms for their ability to bind to the target with high affinity and selectivity in cell culture fluid. Lead peptides were evaluated on resin in batch conditions and compared with a commercially available resin to evaluate their efficacy. Two lead candidates identified from microarray studies provided high binding capacity to the target while demonstrating high selectivity against culture contaminants and product variants compared to a commercial resin system. These findings provide a proof-of-concept for developing affinity peptide-based bioseparations processes for a target biologic. Peptide affinity ligand design and screening approaches presented in this work can also be easily translated to other biologics of interest. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018. © 2018 American Institute of Chemical Engineers.

Adsorptive detoxification of fermentation inhibitors in acid pretreated liquor using functionalized polymer designed by molecular simulation.

Science.gov (United States)

Devendra, Leena P; Pandey, Ashok

2017-11-01

Acid pretreatment is the most common method employed in the lignocellulosic biorefinery leading to the separation of pentose and hexose sugar. The liquor obtained after pretreatment (acid pretreatment liquor or APL) needs to be detoxified prior to fermentation. The aim of this study was to design functional groups on a polymer matrix which are selective in their interaction to inhibitors with little or no specificity to sugars. Molecular modeling was used as a tool to design a suitable adsorbent for selective adsorption of inhibitors from a complex mixture of APL. Phenyl glycine-p-sulfonic acid loaded on chloromethylated polystyrene polymer was designed as an adsorbent for selective interaction with inhibitors. Experimental verification of the selectivity was successfully achieved. The current study provides insights on the adsorptive separation processes at the molecular level by design of specific adsorbent which can be tailor made for the better selectivity of the desired component.

Bioinformatics and multiepitope DNA immunization to design rational snake antivenom.

Directory of Open Access Journals (Sweden)

Simon C Wagstaff

2006-06-01

Full Text Available Snake venom is a potentially lethal and complex mixture of hundreds of functionally diverse proteins that are difficult to purify and hence difficult to characterize. These difficulties have inhibited the development of toxin-targeted therapy, and conventional antivenom is still generated from the sera of horses or sheep immunized with whole venom. Although life-saving, antivenoms contain an immunoglobulin pool of unknown antigen specificity and known redundancy, which necessitates the delivery of large volumes of heterologous immunoglobulin to the envenomed victim, thus increasing the risk of anaphylactoid and serum sickness adverse effects. Here we exploit recent molecular sequence analysis and DNA immunization tools to design more rational toxin-targeted antivenom.We developed a novel bioinformatic strategy that identified sequences encoding immunogenic and structurally significant epitopes from an expressed sequence tag database of a venom gland cDNA library of Echis ocellatus, the most medically important viper in Africa. Focusing upon snake venom metalloproteinases (SVMPs that are responsible for the severe and frequently lethal hemorrhage in envenomed victims, we identified seven epitopes that we predicted would be represented in all isomers of this multimeric toxin and that we engineered into a single synthetic multiepitope DNA immunogen (epitope string. We compared the specificity and toxin-neutralizing efficacy of antiserum raised against the string to antisera raised against a single SVMP toxin (or domains or antiserum raised by conventional (whole venom immunization protocols. The SVMP string antiserum, as predicted in silico, contained antibody specificities to numerous SVMPs in E. ocellatus venom and venoms of several other African vipers. More significantly, the antiserum cross-specifically neutralized hemorrhage induced by E. ocellatus and Cerastes cerastes cerastes venoms.These data provide valuable sequence and structure

Artificially Engineered Protein Polymers.

Science.gov (United States)

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.

Biomolecule-functionalized polymer brushes.

Science.gov (United States)

Jiang, Hui; Xu, Fu-Jian

2013-04-21

Functional polymer brushes have been utilized extensively for the immobilization of biomolecules, which is of crucial importance for the development of biosensors and biotechnology. Recent progress in polymerization methods, in particular surface-initiated atom transfer radical polymerization (ATRP), has provided a unique means for the design and synthesis of new biomolecule-functionalized polymer brushes. This current review summarizes such recent research activities. The different preparation strategies for biomolecule immobilization through polymer brush spacers are described in detail. The functional groups of the polymer brushes used for biomolecule immobilization include epoxide, carboxylic acid, hydroxyl, aldehyde, and amine groups. The recent research activities indicate that functional polymer brushes become versatile and powerful spacers for immobilization of various biomolecules to maximize their functionalities. This review also demonstrates that surface-initiated ATRP is used more frequently than other polymerization methods in the designs of new biomolecule-functionalized polymer brushes.

Identification and design of novel polymer-based mechanical transducers: A nano-structural model for thin film indentation

Energy Technology Data Exchange (ETDEWEB)

Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J., E-mail: dsirbuly@ucsd.edu [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States)

2014-09-14

Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.

Identification and design of novel polymer-based mechanical transducers: A nano-structural model for thin film indentation

International Nuclear Information System (INIS)

Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J.

2014-01-01

Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.

Polymer based tunneling sensor

Science.gov (United States)

Cui, Tianhong (Inventor); Wang, Jing (Inventor); Zhao, Yongjun (Inventor)

2006-01-01

A process for fabricating a polymer based circuit by the following steps. A mold of a design is formed through a lithography process. The design is transferred to a polymer substrate through a hot embossing process. A metal layer is then deposited over at least part of said design and at least one electrical lead is connected to said metal layer.

Pragmatics & rationality.

OpenAIRE

Allott, N. E.

2007-01-01

This thesis is about the reconciliation of realistic views of rationality with inferential-intentional theories of communication. Grice (1957 1975) argued that working out what a speaker meant by an utterance is a matter of inferring the speaker's intentions on the presumption that she is acting rationally. This is abductive inference: inference to the best explanation for the utterance. Thus an utterance both rationalises and causes the interpretation the hearer constructs. Human rationality...

Tailoring the mechanical properties by molecular integration of flexible and stiff polymer networks.

Science.gov (United States)

Wan, Haixiao; Shen, Jianxiang; Gao, Naishen; Liu, Jun; Gao, Yangyang; Zhang, Liqun

2018-03-28

Designing a multiple-network structure at the molecular level to tailor the mechanical properties of polymeric materials is of great scientific and technological importance. Through the coarse-grained molecular dynamics simulation, we successfully construct an interpenetrating polymer network (IPN) composed of a flexible polymer network and a stiff polymer network. First, we find that there is an optimal chain stiffness for a single network (SN) to achieve the best stress-strain behavior. Then we turn to study the mechanical behaviors of IPNs. The result shows that the stress-strain behaviors of the IPNs appreciably exceed the sum of that of the corresponding single flexible and stiff network, which highlights the advantage of the IPN structure. By systematically varying the stiffness of the stiff polymer network of the IPNs, optimal stiffness also exists to achieve the best performance. We attribute this to a much larger contribution of the non-bonded interaction energy. Last, the effect of the component concentration ratio is probed. With the increase of the concentration of the flexible network, the stress-strain behavior of the IPNs is gradually enhanced, while an optimized concentration (around 60% molar ration) of the stiff network occurs, which could result from the dominant role of the enthalpy rather than the entropy. In general, our work is expected to provide some guidelines to better tailor the mechanical properties of the IPNs made of a flexible network and a stiff network, by manipulating the stiffness of the stiff polymer network and the component concentration ratio.

Experiments towards establishing of design rules for R2R-UV-NIL with polymer working shims

Science.gov (United States)

Nees, Dieter; Ruttloff, Stephan; Palfinger, Ursula; Stadlober, Barbara

2016-03-01

Roll-to-Roll-UV-nanoimprint lithography (R2R-UV-NIL) enables high resolution large area patterning of flexible substrates and is therefore of increasing industrial interest. We have set up a custom-made R2R-UV-NIL pilot machine which is able to convert 10 inch wide web with velocities of up to 30 m/min. In addition, we have developed self-replicable UV-curable resins with tunable surface energy and Young's modulus for UV-imprint material as well as for polymer working stamp/shim manufacturing. Now we have designed test patterns for the evaluation of the impact of structure shape, critical dimension, pitch, depth, side wall angle and orientation relative to the web movement onto the imprint fidelity and working shim life time. We have used female (recessed structures) silicon masters of that design with critical dimensions between CD = 200 nm and 1600 nm, and structure depths of d = 500 nm and 1000 nm - all with vertical as well as inclined side walls. These entire master patterns have been transferred onto single male (protruding structures) R2R polymer working shims. The polymer working shims have been used for R2R-UV-NIL runs of several hundred meters and the imprint fidelity and process stability of the various test patterns have been compared. This study is intended as a first step towards establishing of design rules and developing of nanoimprint proximity correction strategies for industrial R2R-UV-NIL processes using polymer working shims.

Peptide/protein-polymer conjugates: synthetic strategies and design concepts.

Science.gov (United States)

Gauthier, Marc A; Klok, Harm-Anton

2008-06-21

This feature article provides a compilation of tools available for preparing well-defined peptide/protein-polymer conjugates, which are defined as hybrid constructs combining (i) a defined number of peptide/protein segments with uniform chain lengths and defined monomer sequences (primary structure) with (ii) a defined number of synthetic polymer chains. The first section describes methods for post-translational, or direct, introduction of chemoselective handles onto natural or synthetic peptides/proteins. Addressed topics include the residue- and/or site-specific modification of peptides/proteins at Arg, Asp, Cys, Gln, Glu, Gly, His, Lys, Met, Phe, Ser, Thr, Trp, Tyr and Val residues and methods for producing peptides/proteins containing non-canonical amino acids by peptide synthesis and protein engineering. In the second section, methods for introducing chemoselective groups onto the side-chain or chain-end of synthetic polymers produced by radical, anionic, cationic, metathesis and ring-opening polymerization are described. The final section discusses convergent and divergent strategies for covalently assembling polymers and peptides/proteins. An overview of the use of chemoselective reactions such as Heck, Sonogashira and Suzuki coupling, Diels-Alder cycloaddition, Click chemistry, Staudinger ligation, Michael's addition, reductive alkylation and oxime/hydrazone chemistry for the convergent synthesis of peptide/protein-polymer conjugates is given. Divergent approaches for preparing peptide/protein-polymer conjugates which are discussed include peptide synthesis from synthetic polymer supports, polymerization from peptide/protein macroinitiators or chain transfer agents and the polymerization of peptide side-chain monomers.

Baseline rationing

DEFF Research Database (Denmark)

Hougaard, Jens Leth; Moreno-Ternero, Juan D.; Østerdal, Lars Peter Raahave

The standard problem of adjudicating conflicting claims describes a situation in which a given amount of a divisible good has to be allocated among agents who hold claims against it exceeding the available amount. This paper considers more general rationing problems in which, in addition to claims...... to international protocols for the reduction of greenhouse emissions, or water distribution in drought periods. We define a family of allocation methods for such general rationing problems - called baseline rationing rules - and provide an axiomatic characterization for it. Any baseline rationing rule within...... the family is associated with a standard rule and we show that if the latter obeys some properties reflecting principles of impartiality, priority and solidarity, the former obeys them too....

Predictive modelling-based design and experiments for synthesis and spinning of bioinspired silk fibres

Science.gov (United States)

Gronau, Greta; Jacobsen, Matthew M.; Huang, Wenwen; Rizzo, Daniel J.; Li, David; Staii, Cristian; Pugno, Nicola M.; Wong, Joyce Y.; Kaplan, David L.; Buehler, Markus J.

2016-01-01

Scalable computational modelling tools are required to guide the rational design of complex hierarchical materials with predictable functions. Here, we utilize mesoscopic modelling, integrated with genetic block copolymer synthesis and bioinspired spinning process, to demonstrate de novo materials design that incorporates chemistry, processing and material characterization. We find that intermediate hydrophobic/hydrophilic block ratios observed in natural spider silks and longer chain lengths lead to outstanding silk fibre formation. This design by nature is based on the optimal combination of protein solubility, self-assembled aggregate size and polymer network topology. The original homogeneous network structure becomes heterogeneous after spinning, enhancing the anisotropic network connectivity along the shear flow direction. Extending beyond the classical polymer theory, with insights from the percolation network model, we illustrate the direct proportionality between network conductance and fibre Young's modulus. This integrated approach provides a general path towards de novo functional network materials with enhanced mechanical properties and beyond (optical, electrical or thermal) as we have experimentally verified. PMID:26017575

Predictive modelling-based design and experiments for synthesis and spinning of bioinspired silk fibres.

Science.gov (United States)

Lin, Shangchao; Ryu, Seunghwa; Tokareva, Olena; Gronau, Greta; Jacobsen, Matthew M; Huang, Wenwen; Rizzo, Daniel J; Li, David; Staii, Cristian; Pugno, Nicola M; Wong, Joyce Y; Kaplan, David L; Buehler, Markus J

2015-05-28

Scalable computational modelling tools are required to guide the rational design of complex hierarchical materials with predictable functions. Here, we utilize mesoscopic modelling, integrated with genetic block copolymer synthesis and bioinspired spinning process, to demonstrate de novo materials design that incorporates chemistry, processing and material characterization. We find that intermediate hydrophobic/hydrophilic block ratios observed in natural spider silks and longer chain lengths lead to outstanding silk fibre formation. This design by nature is based on the optimal combination of protein solubility, self-assembled aggregate size and polymer network topology. The original homogeneous network structure becomes heterogeneous after spinning, enhancing the anisotropic network connectivity along the shear flow direction. Extending beyond the classical polymer theory, with insights from the percolation network model, we illustrate the direct proportionality between network conductance and fibre Young's modulus. This integrated approach provides a general path towards de novo functional network materials with enhanced mechanical properties and beyond (optical, electrical or thermal) as we have experimentally verified.

Rationing with baselines

DEFF Research Database (Denmark)

Hougaard, Jens Leth; Moreno-Ternero, Juan D.; Østerdal, Lars Peter Raahave

2013-01-01

We introduce a new operator for general rationing problems in which, besides conflicting claims, individual baselines play an important role in the rationing process. The operator builds onto ideas of composition, which are not only frequent in rationing, but also in related problems...... such as bargaining, choice, and queuing. We characterize the operator and show how it preserves some standard axioms in the literature on rationing. We also relate it to recent contributions in such literature....

Protein engineering of Bacillus acidopullulyticus pullulanase for enhanced thermostability using in silico data driven rational design methods.

Science.gov (United States)

Chen, Ana; Li, Yamei; Nie, Jianqi; McNeil, Brian; Jeffrey, Laura; Yang, Yankun; Bai, Zhonghu

2015-10-01

Thermostability has been considered as a requirement in the starch processing industry to maintain high catalytic activity of pullulanase under high temperatures. Four data driven rational design methods (B-FITTER, proline theory, PoPMuSiC-2.1, and sequence consensus approach) were adopted to identify the key residue potential links with thermostability, and 39 residues of Bacillus acidopullulyticus pullulanase were chosen as mutagenesis targets. Single mutagenesis followed by combined mutagenesis resulted in the best mutant E518I-S662R-Q706P, which exhibited an 11-fold half-life improvement at 60 °C and a 9.5 °C increase in Tm. The optimum temperature of the mutant increased from 60 to 65 °C. Fluorescence spectroscopy results demonstrated that the tertiary structure of the mutant enzyme was more compact than that of the wild-type (WT) enzyme. Structural change analysis revealed that the increase in thermostability was most probably caused by a combination of lower stability free-energy and higher hydrophobicity of E518I, more hydrogen bonds of S662R, and higher rigidity of Q706P compared with the WT. The findings demonstrated the effectiveness of combined data-driven rational design approaches in engineering an industrial enzyme to improve thermostability. Copyright © 2015 Elsevier Inc. All rights reserved.

Rational design of metal-organic electronic devices: A computational perspective

Science.gov (United States)

Chilukuri, Bhaskar

engineers to choose the appropriate metal electrodes considering the chemical interactions at the interface. Additionally, the calculations performed on the interfaces provided valuable insight into binding energies, charge redistribution, change in the energy levels, dipole formation, etc., which are important parameters to consider while fabricating an electronic device. The research described in this dissertation highlights the application of unique computational modeling methods at different levels of theory to guide the experimental chemists and device engineers toward a rational design of transition metal based electronic devices with low cost and high performance.

Rational design and optimization of downstream processes of virus particles for biopharmaceutical applications: current advances.

Science.gov (United States)

Vicente, Tiago; Mota, José P B; Peixoto, Cristina; Alves, Paula M; Carrondo, Manuel J T

2011-01-01

The advent of advanced therapies in the pharmaceutical industry has moved the spotlight into virus-like particles and viral vectors produced in cell culture holding great promise in a myriad of clinical targets, including cancer prophylaxis and treatment. Even though a couple of cases have reached the clinic, these products have yet to overcome a number of biological and technological challenges before broad utilization. Concerning the manufacturing processes, there is significant research focusing on the optimization of current cell culture systems and, more recently, on developing scalable downstream processes to generate material for pre-clinical and clinical trials. We review the current options for downstream processing of these complex biopharmaceuticals and underline current advances on knowledge-based toolboxes proposed for rational optimization of their processing. Rational tools developed to increase the yet scarce knowledge on the purification processes of complex biologicals are discussed as alternative to empirical, "black-boxed" based strategies classically used for process development. Innovative methodologies based on surface plasmon resonance, dynamic light scattering, scale-down high-throughput screening and mathematical modeling for supporting ion-exchange chromatography show great potential for a more efficient and cost-effective process design, optimization and equipment prototyping. Copyright © 2011 Elsevier Inc. All rights reserved.

Solid polymer fuel cell stationary power generation design studies

Energy Technology Data Exchange (ETDEWEB)

Pyke, S.H.; Wood, A.; Williams, G.J.; Kearney, P.

2000-07-01

This report summarises the results of a study investigating potential markets for solid polymer fuel cells (SPFC) stationary power generating systems and evaluating design options for grid connected and stand-alone systems. The specification of potential application for SPFC systems, initial modelling and economic analysis of twelve candidate SPFC applications, and the ranking and evaluation of candidate applications are examined. Details are given of performance modelling and economic analysis of four preferred SPFC systems (domestic, commercial, light industrial, and transportable generation), and comparison of SPFC with competing technologies. The economics of SPFC and conventional technologies for commercial applications are compared and market opportunities and potential barriers to commercialisation are identified.

Evolutionary and Comparative Genomics to Drive Rational Drug Design, with Particular Focus on Neuropeptide Seven-Transmembrane Receptors.

Science.gov (United States)

Furlong, Michael; Seong, Jae Young

2017-01-01

Seven transmembrane receptors (7TMRs), also known as G protein-coupled receptors, are popular targets of drug development, particularly 7TMR systems that are activated by peptide ligands. Although many pharmaceutical drugs have been discovered via conventional bulk analysis techniques the increasing availability of structural and evolutionary data are facilitating change to rational, targeted drug design. This article discusses the appeal of neuropeptide-7TMR systems as drug targets and provides an overview of concepts in the evolution of vertebrate genomes and gene families. Subsequently, methods that use evolutionary concepts and comparative analysis techniques to aid in gene discovery, gene function identification, and novel drug design are provided along with case study examples.

Rational design of hypoallergens applied to the major cat allergen Fel d 1.

Science.gov (United States)

Saarne, T; Kaiser, L; Grönlund, H; Rasool, O; Gafvelin, G; van Hage-Hamsten, M

2005-05-01

Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients.

Personal Autonomy and Rational Suicide.

Science.gov (United States)

Webber, May A.; Shulman, Ernest

That certain suicides (which can be designated as rational) ought not to be interfered with is closely tied to the notion of the "right to autonomy." Specifically it is because the individual in question has this right that interference is prohibited. A proper understanding of the right to autonomy, while essential to understanding why…

Polymer-Based Surfaces Designed to Reduce Biofilm Formation: From Antimicrobial Polymers to Strategies for Long-Term Applications.

Science.gov (United States)

Riga, Esther K; Vöhringer, Maria; Widyaya, Vania Tanda; Lienkamp, Karen

2017-10-01

Contact-active antimicrobial polymer surfaces bear cationic charges and kill or deactivate bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). The exact mechanism of this interaction is still under debate. While cationic antimicrobial polymer surfaces can be very useful for short-term applications, they lose their activity once they are contaminated by a sufficiently thick layer of adhering biomolecules or bacterial cell debris. This layer shields incoming bacteria from the antimicrobially active cationic surface moieties. Besides discussing antimicrobial surfaces, this feature article focuses on recent strategies that were developed to overcome the contamination problem. This includes bifunctional materials with simultaneously presented antimicrobial and protein-repellent moieties; polymer surfaces that can be switched from an antimicrobial, cell-attractive to a cell-repellent state; polymer surfaces that can be regenerated by enzyme action; degradable antimicrobial polymers; and antimicrobial polymer surfaces with removable top layers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards Rational Design Method for Strengthening of Concrete Structures by External Bonding

Directory of Open Access Journals (Sweden)

Furuuchi H.

2012-01-01

Full Text Available Many infrastructures need to be repaired or strengthened due to various reasons, such as unexpected deterioration and changes in performance requirement. This paper presents the following recent achievements by the authors’ group on design method for flexural strengthening of concrete structures by external bonding; (i fracture characteristics of interface between substrate concrete and cementitious overlay, (ii crack spacing of flexural strengthened beams, which affects debonding strength, (iii strengths of intermediate crack (IC debonding and end peeling, (iv strength of concrete cover separation, and (v effectiveness of strengthening by external bonding. A unified approach for flexural strengthening by steel plate, fiber reinforced polymer lami¬nate and cementitious overlay, for both intermediate crack (IC debonding, including end peeling, and concrete cover separation is pre¬sented with consideration of crack spacing in the streng¬thened members. Appropriate interfacial rough¬¬¬ness to achieve efficient interface bond property is clari¬fied and the concept of effectiveness of strengthen¬ing is proposed for better strengthening design.

Design, fabrication and performance tests for a polymer-based flexible flat heat pipe

International Nuclear Information System (INIS)

Hsieh, Shou-Shing; Yang, Ya-Ru

2013-01-01

Highlights: ► Fabrication of a polymer-based flexible flat heat pipe. ► Bending angle of 15° will lead to a better thermal performance of the system. ► Powers higher than 12.67 W can be transferred/delivered. - Abstract: In this paper, we report on the novel design, fabrication and performance tests for a polymer-based flexible flat heat pipe (FHP) with a bending angle in the range of 15–90°. Each heat pipe is 4 mm thick, 20 mm wide and 80 mm long, with two layers of No. 250 copper mesh as the wicking material. A copper/silicone rubber hybrid structure is designed and fabricated to achieve the flexibility of the heat pipe. Thermal characteristics are measured and studied for de-ionized water under different working conditions. Experimental results reveal that a bending angle of 15° on the vertical plane has a better thermal performance than those of heat pipes with/without bending. In addition, a higher power of 12.67 W can be transferred/delivered

Inaugurating Rationalization: Three Field Studies Find Increased Rationalization When Anticipated Realities Become Current.

Science.gov (United States)

Laurin, Kristin

2018-04-01

People will often rationalize the status quo, reconstruing it in an exaggeratedly positive light. They will even rationalize the status quo they anticipate, emphasizing the upsides and minimizing the downsides of sociopolitical realities they expect to take effect. Drawing on recent findings on the psychological triggers of rationalization, I present results from three field studies, one of which was preregistered, testing the hypothesis that an anticipated reality becoming current triggers an observable boost in people's rationalizations. San Franciscans rationalized a ban on plastic water bottles, Ontarians rationalized a targeted smoking ban, and Americans rationalized the presidency of Donald Trump, more in the days immediately after these realities became current compared with the days immediately before. Additional findings show evidence for a mechanism underlying these behaviors and rule out alternative accounts. These findings carry implications for scholarship on rationalization, for understanding protest behavior, and for policymakers.

Realization theory for rational systems: Minimal rational realizations

NARCIS (Netherlands)

J. Nemcová (Jana); J.H. van Schuppen (Jan)

2010-01-01

htmlabstractThe study of realizations of response maps is a topic of control and system theory. Realization theory is used in system identification and control synthesis. A minimal rational realization of a given response map p is a rational realization of p such that the dimension of its state

The Boundedly Rational User Equilibrium : A parametric analysis with application to the Network Design Problem

NARCIS (Netherlands)

Eikenbroek, Oskar Adriaan Louis; Still, Georg J.; van Berkum, E.C.; Kern, Walter

In this paper, we study a static traffic assignment that accounts for the boundedly rational route choice behavior of travelers. This assignment induces uncertainties to the ex-ante evaluation of a policy measure: the boundedly rational assignment is non-unique and the indifference band is an

Elaborating and Making Rational Decisions in Designing Process Operations of a Group of Holes

Directory of Open Access Journals (Sweden)

A. I. Solov'ev

2015-01-01

Full Text Available To manufacture engineering products are used expensive multi-purpose CNC machines with five operated coordinates, allowing a single setup of the work-piece to process a group of holes in the housing part from all sides.Because of the haphazard arrangement of a large number of holes available in the space it is difficult to ensure the effective use of these machines.Onsite operational research, conducted on six CNC GS-500 models, involved actual observations and time measurements during 15 working shifts, processing of observation results, and calculations of equipment performance parameters such as machine utilization rate, arrangement and changeover time loss, and real output. Time loss (downtime because of arrangement amounted 44.52%, while that of due to changeover was 20.1% of the total downtime value. These downtimes hide irrational design solutions concerning the engineering process and a large number of changeovers for a new operation to process a group of the specified work-pieces.It is found that to reduce the changeover downtimes it is necessary to increase, first of all, the average number of single tool travels per one setup in generalized characteristics of a group of the work-pieces. That means to increase a changeover concentration of processing within a single operation, as well as to choose rational values for machining a batch of the work-pieces. Under study conditions, it is, at least. 20-50 pieces.To implement a development of the principle of increasing concentration of the processing changeovers it is advised to apply the developed mathematical models, algorithms, and programs that can be used, as modules or their parts, in computer-aided design (CAD systems. This allows a 3-5 times reduction in time to find the rational option of the work-piece position on the machine work surface when developing a process technology, a review and an analysis of more than the usual number of such possible options. It also improves the

The Effect of Soy Sauce Waste in Ration on Performance of Mojosari Duck

Directory of Open Access Journals (Sweden)

G. A. A. Larasati

2017-06-01

Full Text Available The purpose of study was to determined the effect of soy sauce waste in ration in the ration on the performance of Mojosari duck. The materials used were 240 of Mojosari which are 20 weeks olds with average body weight 1,385.0 ± 130.85 grams (CV = 9.44%. Feed ingredients used were, rice bran, soybean meal, yellow corn, fish meal, pollard and premix. The design that used was Completely Randomized Design (CRD with 4 treatments and 6 replications.The treatment applied soy sauce waste at level 5, 7,5 and 10%. The parameters observed were consumption, egg production, feed conversion. The data were analyzed by analysis of variance with F test. The results showed that soy sauce waste did not effected on performance (consumption of ration, egg production, ration conversion of Mojosari duck. The conclusion of this research is soy sauce waste be used as feed stuff of Mojosari duck ration until level 10%.

Many faces of rationality: Implications of the great rationality debate for clinical decision‐making

Science.gov (United States)

Elqayam, Shira

2017-01-01

Abstract Given that more than 30% of healthcare costs are wasted on inappropriate care, suboptimal care is increasingly connected to the quality of medical decisions. It has been argued that personal decisions are the leading cause of death, and 80% of healthcare expenditures result from physicians' decisions. Therefore, improving healthcare necessitates improving medical decisions, ie, making decisions (more) rational. Drawing on writings from The Great Rationality Debate from the fields of philosophy, economics, and psychology, we identify core ingredients of rationality commonly encountered across various theoretical models. Rationality is typically classified under umbrella of normative (addressing the question how people “should” or “ought to” make their decisions) and descriptive theories of decision‐making (which portray how people actually make their decisions). Normative theories of rational thought of relevance to medicine include epistemic theories that direct practice of evidence‐based medicine and expected utility theory, which provides the basis for widely used clinical decision analyses. Descriptive theories of rationality of direct relevance to medical decision‐making include bounded rationality, argumentative theory of reasoning, adaptive rationality, dual processing model of rationality, regret‐based rationality, pragmatic/substantive rationality, and meta‐rationality. For the first time, we provide a review of wide range of theories and models of rationality. We showed that what is “rational” behaviour under one rationality theory may be irrational under the other theory. We also showed that context is of paramount importance to rationality and that no one model of rationality can possibly fit all contexts. We suggest that in context‐poor situations, such as policy decision‐making, normative theories based on expected utility informed by best research evidence may provide the optimal approach to medical decision�

Rational design, synthesis, and pharmacological evaluation of 2-azanorbornane-3-exo,5-endo-dicarboxylic acid

DEFF Research Database (Denmark)

Bunch, Lennart; Liljefors, Tommy; Greenwood, Jeremy R

2003-01-01

conformationally restricted (S)-glutamic acid (Glu) analogue intended as a mimic of the folded Glu conformation. The synthesis of 1 was completed in its racemic form in eight steps from commercially available starting materials. As a key step, the first facially selective hydroboration of a 5-methylidene[2......The design and synthesis of conformationally restricted analogues of alpha-amino acids is an often used strategy in medicinal chemistry research. Here we present the rational design, synthesis, and pharmacological evaluation of 2-azanorbornane-3-exo,5-endo-dicarboxylic acid (1), a novel...... studies on native 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) (IC(50) > 300 microM, [(3)H]AMPA) or kainic acid (IC(50) > 160 microM, [(3)H]kainic acid) receptors nor in binding studies on the cloned iGluR5,6 subtypes (IC(50) > 300 microM, [(3)H]kainic acid)....

Rational design of single-molecule magnets: a supramolecular approach.

Science.gov (United States)

Glaser, Thorsten

2011-01-07

Since the discovery that Mn(12)OAc acts as a single-molecule magnet (SMM), an increasing number of transition metal complexes have been demonstrated to behave as SMMs. The signature of a SMM is a slow relaxation of the magnetization at low temperatures accompanied by a magnetic hysteresis. The origin of SMM behaviour is the existence of an appreciable thermal barrier U for spin-reversal called magnetic anisotropy barrier which is related to the combination of a large total spin ground state (S(t)) and an easy-axis magnetic anisotropy. The extensive research on Mn(12)OAc and other SMMs has established more prerequisites for a rational development of new SMMs besides the high-spin ground state and the magnetic anisotropy: the symmetry should be at least C(3) to minimize the quantum tunneling of the magnetization through the anisotropy barrier but lower than cubic to avoid the cancellation of the local anisotropies upon projection onto the spin ground state. Based on these prerequisites, we have designed the ligand triplesalen which combines the phloroglucinol bridging unit for high spin ground states by the spin-polarization mechanism with a salen-like ligand environment for single-site magnetic anisotropies by a strong tetragonal ligand field. The C(3) symmetric, trinuclear complexes of the triplesalen ligand (talen(t-Bu(2)))(6-) exhibit a strong ligand folding resulting in an overall bowl-shaped molecular structure. This ligand folding preorganizes the axial coordination sites of the metal salen subunits for the complementary binding of three facial nitrogen atoms of a hexacyanometallate unit. This leads to a high driving force for the formation of heptanuclear complexes [M(t)(6)M(c)](n+) by the assembly of three molecular building blocks. Attractive van der Waals interactions of the tert-butyl phenyl units of two triplesalen trinuclear building blocks increase the driving force. In this respect, we have been able to synthesize the isostructural series [Mn(III)(6

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

Science.gov (United States)

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.

A functional monomer is not enough: principal component analysis of the influence of template complexation in pre-polymerization mixtures on imprinted polymer recognition and morphology.

Science.gov (United States)

Golker, Kerstin; Karlsson, Björn C G; Rosengren, Annika M; Nicholls, Ian A

2014-11-10

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

Many faces of rationality: Implications of the great rationality debate for clinical decision-making.

Science.gov (United States)

Djulbegovic, Benjamin; Elqayam, Shira

2017-10-01

Given that more than 30% of healthcare costs are wasted on inappropriate care, suboptimal care is increasingly connected to the quality of medical decisions. It has been argued that personal decisions are the leading cause of death, and 80% of healthcare expenditures result from physicians' decisions. Therefore, improving healthcare necessitates improving medical decisions, ie, making decisions (more) rational. Drawing on writings from The Great Rationality Debate from the fields of philosophy, economics, and psychology, we identify core ingredients of rationality commonly encountered across various theoretical models. Rationality is typically classified under umbrella of normative (addressing the question how people "should" or "ought to" make their decisions) and descriptive theories of decision-making (which portray how people actually make their decisions). Normative theories of rational thought of relevance to medicine include epistemic theories that direct practice of evidence-based medicine and expected utility theory, which provides the basis for widely used clinical decision analyses. Descriptive theories of rationality of direct relevance to medical decision-making include bounded rationality, argumentative theory of reasoning, adaptive rationality, dual processing model of rationality, regret-based rationality, pragmatic/substantive rationality, and meta-rationality. For the first time, we provide a review of wide range of theories and models of rationality. We showed that what is "rational" behaviour under one rationality theory may be irrational under the other theory. We also showed that context is of paramount importance to rationality and that no one model of rationality can possibly fit all contexts. We suggest that in context-poor situations, such as policy decision-making, normative theories based on expected utility informed by best research evidence may provide the optimal approach to medical decision-making, whereas in the context

Some Key Features to Consider When Studying Acrylamide-Based Polymers for Chemical Enhanced Oil Recovery Quelques caractéristiques clés à considérer lors de l’étude des polymères à base d’acrylamide en vue de leur utilisation pour la récupération assistée chimique du pétrole

Directory of Open Access Journals (Sweden)

Thomas A.

2013-02-01

Full Text Available Among Chemical Enhanced Oil Recovery (CEOR methods, polymer flooding is a straightforward technique with a long commercial history and proven results. It consists in injecting polymer-augmented water into a subterranean formation in order to improve, thanks to the viscosity increase, the sweep efficiency in the reservoir and provides a mobility control between water and the hydrocarbons. However, implementing successfully a polymer flood in the field requires specific know-how to avoid polymer degradation and associated viscosity loss. The first stage begins with the selection of the right polymer for the reservoir, depending on the water quality, temperature, permeability and presence of contaminants such as iron, hydrogen sulfide and oxygen. Several laboratory tests have to be performed to ensure the long term stability of the product as well as core flooding experiments to check parameters such as injectivity and propagation through the porous medium. The next step is the design and selection of equipment for the dissolution and the injection of the polymer solution into the reservoir. Surface facilities are paramount for the quality of the injected solution: the goal is to allow a good hydration, maturation and transport of the solution while avoiding any type of degradation that can occur either chemically (oxygen ingress or mechanically (chokes, centrifugal pumps. Another aspect that can be assessed is the degradation of the back -produced polymer. Several studies have shown that there is no influence of the polymer on the separation of crude and water; the polymer being water-soluble. However, when the viscosity of the produced water is above 4 mPa.s, a treatment may be operated before the water treatment process to avoid any difficulty in the surface facilities and an optimum efficiency. Parmi les méthodes chimiques de récupération assistée du pétrole, l’injection de polymère est une technique simple, connue de longue date et qui

Cascade use indicators for selected biopolymers: Are we aiming for the right solutions in the design for recycling of bio-based polymers?

Science.gov (United States)

Hildebrandt, Jakob; Bezama, Alberto; Thrän, Daniela

2017-04-01

When surveying the trends and criteria for the design for recycling (DfR) of bio-based polymers, priorities appear to lie in energy recovery at the end of the product life of durable products, such as bio-based thermosets. Non-durable products made of thermoplastic polymers exhibit good properties for material recycling. The latter commonly enjoy growing material recycling quotas in countries that enforce a landfill ban. Quantitative and qualitative indicators are needed for characterizing progress in the development towards more recycling friendly bio-based polymers. This would enable the deficits in recycling bio-based plastics to be tracked and improved. The aim of this paper is to analyse the trends in the DfR of bio-based polymers and the constraints posed by the recycling infrastructure on plastic polymers from a systems perspective. This analysis produces recommendations on how life cycle assessment indicators can be introduced into the dialogue between designers and recyclers in order to promote DfR principles to enhance the cascading use of bio-based polymers within the bioeconomy, and to meet circular economy goals.

Cascade use indicators for selected biopolymers: Are we aiming for the right solutions in the design for recycling of bio-based polymers?

Science.gov (United States)

Hildebrandt, Jakob; Bezama, Alberto; Thrän, Daniela

2017-01-01

When surveying the trends and criteria for the design for recycling (DfR) of bio-based polymers, priorities appear to lie in energy recovery at the end of the product life of durable products, such as bio-based thermosets. Non-durable products made of thermoplastic polymers exhibit good properties for material recycling. The latter commonly enjoy growing material recycling quotas in countries that enforce a landfill ban. Quantitative and qualitative indicators are needed for characterizing progress in the development towards more recycling friendly bio-based polymers. This would enable the deficits in recycling bio-based plastics to be tracked and improved. The aim of this paper is to analyse the trends in the DfR of bio-based polymers and the constraints posed by the recycling infrastructure on plastic polymers from a systems perspective. This analysis produces recommendations on how life cycle assessment indicators can be introduced into the dialogue between designers and recyclers in order to promote DfR principles to enhance the cascading use of bio-based polymers within the bioeconomy, and to meet circular economy goals. PMID:28097922

Rationally designed polyimides for high-energy density capacitor applications.

Science.gov (United States)

Ma, Rui; Baldwin, Aaron F; Wang, Chenchen; Offenbach, Ido; Cakmak, Mukerrem; Ramprasad, Rampi; Sotzing, Gregory A

2014-07-09

Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.

Rationality and drug use: an experimental approach.

Science.gov (United States)

Blondel, Serge; Lohéac, Youenn; Rinaudo, Stéphane

2007-05-01

In rational addiction theory, higher discount rates encourage drug use. We test this hypothesis in the general framework of rationality and behaviour under risk. We do so using an experimental design with real monetary incentives. The decisions of 34 drug addicts are compared with those of a control group. The decisions of drug users (DU) are not any less consistent with standard theories of behaviour over time and under risk. Further, there is no difference in the estimated discount rate between drug users and the control group, but the former do appear to be more risk-seeking.

Polymer and polymer-hybrid nanoparticles from synthesis to biomedical applications

CERN Document Server

Rangelov, Stanislav

2013-01-01

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

Adolescent rationality.

Science.gov (United States)

Moshman, David

2013-01-01

Adolescents are commonly seen as irrational, a position supported to varying degrees by many developmentalists, who often appeal to recent research on adolescent brains. Careful review of relevant evidence, however, shows that (1) adults are less rational than is generally assumed, (2) adolescents (and adults) are categorically different from children with respect to the attainment of advanced levels of rationality and psychological functioning, and (3) adolescents and adults do not differ categorically from each other with respect to any rational competencies, irrational tendencies, brain structures, or neurological functioning. Development often continues in adolescence and beyond but categorical claims about adolescents as distinct from adults cannot be justified. A review of U.S. Supreme Court decisions concerning intellectual freedom, reproductive freedom, and criminal responsibility shows ongoing ambivalence and confusion about the rationality of adolescents. Developmental theory and research suggest that adolescents should be conceptualized as young adults, not immature brains, with important implications for their roles, rights, and responsibilities.

New approach to design of ceramic/polymer material compounds

International Nuclear Information System (INIS)

Todt, A; Nestler, D; Trautmann, M; Wagner, G

2016-01-01

The damage tolerance of carbon fibre-reinforced ceramic-matrix composite materials depends on their porosity and can be rather significant. Complex structures are difficult to produce. The integration of simple geometric structures of ceramic-matrix composite materials in complex polymer-based hybrid structures is a possible approach of realising those structures. These hybrid material compounds, produced in a cost-efficient way, combine the different advantages of the individual components in one hybrid material compound. In addition the individual parts can be designed to fit a specific application and the resulting forces. All these different advantages result in a significant reduction of not only the production costs and the production time, but also opens up new areas of application, such as the large-scale production of wear-resistant and chemically inert, energy dampening components for reactors or in areas of medicine. The low wettability of the ceramic component however is a disadvantage of this approach. During the course of this contribution, different C/C composite materials with a specific porosity were produced, while adjusting the resin/hardening agent-ratio, as well as the processing parameters. After the production, different penetration tests were conducted with a polymer component. The final part of the article is comprised of the microstructural analysis and the explanation of the mechanical relationships. (paper)

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

International Nuclear Information System (INIS)

Pople, John A.

2001-01-01

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 ( and lt; 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

Design Principles in Polymer-Fullerene BHJ Solar Cells: PBDTTPD as a Case Study

KAUST Repository

Beaujuge, Pierre

2015-01-01

For example, in poly(benzo[1,2-b:4,5-b’]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD), side-chain substituents of various size and branching impart distinct molecular packing distances (i.e., π–π stacking and lamellar spacing), varying degrees of nanostructural order in thin films, and preferential backbone orientation relative to the device substrate.[2-5] While these structural variations seem to correlate with BHJ solar cell performance, with power conversion efficiencies ranging from 4% to 8.5%,[2,3] we believe that other contributing parameters – such as the local conformations between the polymer and the fullerene, and the domain distribution/composition across the BHJ (i.e., pure/mixed phases) – should also be taken into account.[6,7] Other discrete modifications of PBDTTPD’s molecular structure affect polymer performance in BHJ solar cells with PCBM, and our recent developments emphasize how systematic structure-property relationship studies impact the design of efficient polymer donors for BHJ solar cell applications.[8-10] It is important to further our understanding of these effects as we look to continue improving BHJ solar cell efficiencies.

Love and rationality: on some possible rational effects of love

Directory of Open Access Journals (Sweden)

Gustavo Ortiz-Millán

Full Text Available In this paper I defend the idea that rather than disrupting rationality, as the common-sense conception has done it, love may actually help us to develop rational ways of thinking and acting. I make the case for romantic or erotic love, since this is the kind of love that is more frequently associated with irrationality in acting and thinking. I argue that this kind of love may make us develop epistemic and practical forms of rationality. Based on an analysis of its characteristic action tendencies, I argue that love may help us to develop an instrumental form of rationality in determining the best means to achieve the object of love. It may also narrow down the number of practical considerations that may help us to achieve our goals. Finally, love may generate rational ways of belief-formation by framing the parameters taken into account in perception and attention, and by bringing into light only a small portion of the epistemic information available. Love may make us perceive reality more acutely.

Rational design of highly potent HIV-1 fusion inhibitory proteins: Implication for developing antiviral therapeutics

International Nuclear Information System (INIS)

Ni Ling; Gao, George F.; Tien Po

2005-01-01

Recombinant protein containing one heptad-repeat 1 (HR1) segment and one HR2 segment of the HIV-1 gp41 (HR1-HR2) has been shown to fold into thermally stable six-helix bundle, representing the fusogenic core of gp41. In this study, we have used the fusogenic core as a scaffold to design HIV-1 fusion inhibitory proteins by linking another HR1 to the C terminus of HR1-HR2 (HR121) or additional HR2 to the N terminus of HR1-HR2 (HR212). Both recombinant proteins could be abundantly and solubly expressed and easily purified, exhibiting high stability and potent inhibitory activity on HIV-1 fusion with IC 50 values of 16.2 ± 2.8 and 2.8 ± 0.63 nM, respectively. These suggest that these rationally designed proteins can be further developed as novel anti-HIV-1 therapeutics

Towards Designing Environmentally Stable Conjugated Polymers with very Small Band-Gaps

International Nuclear Information System (INIS)

Hong, Sung Y.; Kim, Sung C.

2003-01-01

We have investigated substituent effect on the stabilization energies, and nucleus-independent chemical shifts of pentafulvalenes and on the electronic structures of the corresponding polypentafulvalenes to design environmentally stable semiconductive or conductive polymers. Geometrical optimizations of the molecules were carried out at the density functional level of theory with B3LYP hybrid functional and 6-311+G(d) basis set. Stabilization energies were estimated using isodesmic and homodesmotic reactions. As a criterion of aromaticity nucleus-independent chemical shifts of the molecules were computed using GIAO approach. For the polymers the geometrical parameters were optimized through AM1 band calculations and the electronic structures were obtained through modified extended Huckel band calculations. It is found that strong electronwithdrawing substituents increase isodesmic and homodesmotic stabilization energies of pentafulvalene, though it does not increase the aromaticity. Nitro-substituted pentafulvalene is estimated to have stabilization energy as much as azulene. However, substitution either with electron-donating groups or with electronwithdrawing groups does not significantly affect the electronic structures of polypentafulvalene and poly (vinylenedioxypentafulvalene)

CONTRIBUTIONS TO RATIONAL APPROXIMATION,

Science.gov (United States)

Some of the key results of linear Chebyshev approximation theory are extended to generalized rational functions. Prominent among these is Haar’s...linear theorem which yields necessary and sufficient conditions for uniqueness. Some new results in the classic field of rational function Chebyshev...Furthermore a Weierstrass type theorem is proven for rational Chebyshev approximation. A characterization theorem for rational trigonometric Chebyshev approximation in terms of sign alternation is developed. (Author)

Controlling photophysical properties of ultrasmall conjugated polymer nanoparticles through polymer chain packing

KAUST Repository

Piwonski, Hubert Marek

2017-05-16

Applications of conjugated polymer nanoparticles (Pdots) for imaging and sensing depend on their size, fluorescence brightness and intraparticle energy transfer. The molecular design of conjugated polymers (CPs) has been the main focus of the development of Pdots. Here we demonstrate that proper control of the physical interactions between the chains is as critical as the molecular design. The unique design of twisted CPs and fine-tuning of the reprecipitation conditions allow us to fabricate ultrasmall (3.0–4.5 nm) Pdots with excellent photostability. Extensive photophysical and structural characterization reveals the essential role played by the packing of the polymer chains in the particles in the intraparticle spatial alignment of the emitting sites, which regulate the fluorescence brightness and the intraparticle energy migration efficiency. Our findings enhance understanding of the relationship between chain interactions and the photophysical properties of CP nanomaterials, providing a framework for designing and fabricating functional Pdots for imaging applications.

Rational points, rational curves, and entire holomorphic curves on projective varieties

CERN Document Server

Gasbarri, Carlo; Roth, Mike; Tschinkel, Yuri

2015-01-01

This volume contains papers from the Short Thematic Program on Rational Points, Rational Curves, and Entire Holomorphic Curves and Algebraic Varieties, held from June 3-28, 2013, at the Centre de Recherches Mathématiques, Université de Montréal, Québec, Canada. The program was dedicated to the study of subtle interconnections between geometric and arithmetic properties of higher-dimensional algebraic varieties. The main areas of the program were, among others, proving density of rational points in Zariski or analytic topology on special varieties, understanding global geometric properties of rationally connected varieties, as well as connections between geometry and algebraic dynamics exploring new geometric techniques in Diophantine approximation.

Flame spraying of polymers

International Nuclear Information System (INIS)

Varacalle, D.J. Jr.; Zeek, D.P.; Couch, K.W.; Benson, D.M.; Kirk, S.M.

1997-01-01

Statistical design-of-experiment studies of the thermal spraying of polymer powders are presented. Studies of the subsonic combustion (i.e., Flame) process were conducted in order to determine the quality and economics of polyester and urethane coatings. Thermally sprayed polymer coatings are of interest to several industries for anticorrosion applications, including the chemical, automotive, and aircraft industries. In this study, the coating design has been optimized for a site-specific application using Taguchi-type fractional-factorial experiments. Optimized coating designs are presented for the two powder systems. A substantial range of thermal processing conditions and their effect on the resultant polymer coatings is presented. The coatings were characterized by optical metallography, hardness testing, tensile testing, and compositional analysis. Characterization of the coatings yielded the thickness, bond strength, Knoop microhardness, roughness, deposition efficiency, and porosity. Confirmation testing was accomplished to verify the coating designs

New Incremental Actuators based on Electro-active Polymer: Conceptual, Control, and Driver Design Considerations

DEFF Research Database (Denmark)

Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

2016-01-01

This paper presents an overview of the widely usedconventional linear actuator technologies and existing electroactivepolymer based linear and rotary actuators. It also providesthe conceptual, control and driver design considerations for anew dielectric electro-active polymer (DEAP) based...

Application of 3D-QSAR in the rational design of receptor ligands and enzyme inhibitors.

Science.gov (United States)

Mor, Marco; Rivara, Silvia; Lodola, Alessio; Lorenzi, Simone; Bordi, Fabrizio; Plazzi, Pier Vincenzo; Spadoni, Gilberto; Bedini, Annalida; Duranti, Andrea; Tontini, Andrea; Tarzia, Giorgio

2005-11-01

Quantitative structure-activity relationships (QSARs) are frequently employed in medicinal chemistry projects, both to rationalize structure-activity relationships (SAR) for known series of compounds and to help in the design of innovative structures endowed with desired pharmacological actions. As a difference from the so-called structure-based drug design tools, they do not require the knowledge of the biological target structure, but are based on the comparison of drug structural features, thus being defined ligand-based drug design tools. In the 3D-QSAR approach, structural descriptors are calculated from molecular models of the ligands, as interaction fields within a three-dimensional (3D) lattice of points surrounding the ligand structure. These descriptors are collected in a large X matrix, which is submitted to multivariate analysis to look for correlations with biological activity. Like for other QSARs, the reliability and usefulness of the correlation models depends on the validity of the assumptions and on the quality of the data. A careful selection of compounds and pharmacological data can improve the application of 3D-QSAR analysis in drug design. Some examples of the application of CoMFA and CoMSIA approaches to the SAR study and design of receptor or enzyme ligands is described, pointing the attention to the fields of melatonin receptor ligands and FAAH inhibitors.

Computational smart polymer design based on elastin protein mutability.

Science.gov (United States)

Tarakanova, Anna; Huang, Wenwen; Weiss, Anthony S; Kaplan, David L; Buehler, Markus J

2017-05-01

Soluble elastin-like peptides (ELPs) can be engineered into a range of physical forms, from hydrogels and scaffolds to fibers and artificial tissues, finding numerous applications in medicine and engineering as "smart polymers". Elastin-like peptides are attractive candidates as a platform for novel biomaterial design because they exhibit a highly tunable response spectrum, with reversible phase transition capabilities. Here, we report the design of the first virtual library of elastin-like protein models using methods for enhanced sampling to study the effect of peptide chemistry, chain length, and salt concentration on the structural transitions of ELPs, exposing associated molecular mechanisms. We describe the behavior of the local molecular structure under increasing temperatures and the effect of peptide interactions with nearest hydration shell water molecules on peptide mobility and propensity to exhibit structural transitions. Shifts in the magnitude of structural transitions at the single-molecule scale are explained from the perspective of peptide-ion-water interactions in a library of four unique elastin-like peptide systems. Predictions of structural transitions are subsequently validated in experiment. This library is a valuable resource for recombinant protein design and synthesis as it elucidates mechanisms at the single-molecule level, paving a feedback path between simulation and experiment for smart material designs, with applications in biomedicine and diagnostic devices. Copyright © 2017. Published by Elsevier Ltd.

Study of Hydrophobic and Ionizable Hydrophilic Copolymers at Polymer/Solid and Polymer/Liquid Interfaces

Energy Technology Data Exchange (ETDEWEB)

Perahia, Dvora

2011-11-01

Joint experimental-computational efforts were set to characterize the interfacial effects on the structure and dynamics of polymers consisting of highly rigid hydrophilic-ionizable and hydrophobic sub-units within one polymeric chain casted into thin films of several molecular dimensions. Focusing on the ultra thin film region we separate out the interfacial effects from bulk characteristics. Specifically, the study sought to: identify the parameters that control the formation of a stable polymer-solid interface. The study consists of two components, experimental investigations and computational efforts. The experimental component was designed to derive empirical trends that can be used to correlate the set of coupled polymer molecular parameters with the interfacial characteristics of these polymers, and their response to presence of solvents. The computational study was designed to provide molecular insight into the ensemble averages provided by the experimental efforts on multiple length scales from molecular dimensions, to the nanometer lengths to a macroscopic understanding of solvent interactions with structured polymers. With the ultimate goal of correlating molecular parameters to structure, dynamics and properties of ionic polymers, the first stage of the research began with the study of two systems, one which allowed tailoring the flexibility of the backbone without the presence of ionic groups, but with a potential to sulfonate groups at a later stage, and a polymer whose backbone is rigid and the density of the ionic group can be varied. The combined experimental and computational studies significantly extended the understanding of polymers at interfaces from model systems to polydispersed copolymers with blocks of varying nature and complexity. This new insight directly affects the design of polymers for sustainable energy applications from batteries and fuel cells to solar energy.

In silico design of porous polymer networks: high-throughput screening for methane storage materials.

Science.gov (United States)

Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

2014-04-02

Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

Computational approaches in the design of synthetic receptors - A review.

Science.gov (United States)

Cowen, Todd; Karim, Kal; Piletsky, Sergey

2016-09-14

The rational design of molecularly imprinted polymers (MIPs) has been a major contributor to their reputation as "plastic antibodies" - high affinity robust synthetic receptors which can be optimally designed, and produced for a much reduced cost than their biological equivalents. Computational design has become a routine procedure in the production of MIPs, and has led to major advances in functional monomer screening, selection of cross-linker and solvent, optimisation of monomer(s)-template ratio and selectivity analysis. In this review the various computational methods will be discussed with reference to all the published relevant literature since the end of 2013, with each article described by the target molecule, the computational approach applied (whether molecular mechanics/molecular dynamics, semi-empirical quantum mechanics, ab initio quantum mechanics (Hartree-Fock, Møller-Plesset, etc.) or DFT) and the purpose for which they were used. Detailed analysis is given to novel techniques including analysis of polymer binding sites, the use of novel screening programs and simulations of MIP polymerisation reaction. The further advances in molecular modelling and computational design of synthetic receptors in particular will have serious impact on the future of nanotechnology and biotechnology, permitting the further translation of MIPs into the realms of analytics and medical technology. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental Optimization In Polymer BLEND Composite Preparation Based On Mix Level of Taguchi Robust Design

International Nuclear Information System (INIS)

Abdul Aziz Mohamed; Jaafar Abdullah; Dahlan Mohd; Rozaidi Rasid; Megat Harun AlRashid Megat Ahmad; Mahathir Mohamad; Mohd Hamzah Harun

2012-01-01

L 18 orthogonal array in mix level of Taguchi robust design method was carried out to optimize experimental conditions for the preparation of polymer blend composite. Tensile strength and neutron absorption of the composite were the properties of interest. Filler size, filler loading, ball mixing time and dispersion agent concentration were selected as parameters or factors which are expected to affect the composite properties. As a result of Taguchi analysis, filler loading was the most influencing parameter on the tensile strength and neutron absorption. The least influencing was ball-mixing time. The optimal conditions were determined by using mix-level Taguchi robust design method and a polymer composite with tensile strength of 6.33 MPa was successfully prepared. The composite was found to fully absorb thermal neutron flux of 1.04 x 10 5 n/ cm 2 / s with only 2 mm in thickness. In addition, the filler was also characterized by scanning electron microscopy (SEM) and elemental analysis (EDX). (Author)

Self-assembly and glass-formation in a lattice model of telechelic polymer melts: Influence of stiffness of the sticky bonds

Energy Technology Data Exchange (ETDEWEB)

Xu, Wen-Sheng, E-mail: wsxu@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Freed, Karl F., E-mail: freed@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Department of Chemistry, The University of Chicago, Chicago, Illinois 60637 (United States)

2016-06-07

Telechelic polymers are chain macromolecules that may self-assemble through the association of their two mono-functional end groups (called “stickers”). A deep understanding of the relation between microscopic molecular details and the macroscopic physical properties of telechelic polymers is important in guiding the rational design of telechelic polymer materials with desired properties. The lattice cluster theory (LCT) for strongly interacting, self-assembling telechelic polymers provides a theoretical tool that enables establishing the connections between important microscopic molecular details of self-assembling polymers and their bulk thermodynamics. The original LCT for self-assembly of telechelic polymers considers a model of fully flexible linear chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)], while our recent work introduces a significant improvement to the LCT by including a description of chain semiflexibility for the bonds within each individual telechelic chain [W.-S. Xu and K. F. Freed, J. Chem. Phys. 143, 024901 (2015)], but the physically associative (or called “sticky”) bonds between the ends of the telechelics are left as fully flexible. Motivated by the ubiquitous presence of steric constraints on the association of real telechelic polymers that impart an additional degree of bond stiffness (or rigidity), the present paper further extends the LCT to permit the sticky bonds to be semiflexible but to have a stiffness differing from that within each telechelic chain. An analytical expression for the Helmholtz free energy is provided for this model of linear telechelic polymer melts, and illustrative calculations demonstrate the significant influence of the stiffness of the sticky bonds on the self-assembly and thermodynamics of telechelic polymers. A brief discussion is also provided for the impact of self-assembly on glass-formation by combining the LCT description for this extended model of telechelic polymers with

Self-assembly and glass-formation in a lattice model of telechelic polymer melts: Influence of stiffness of the sticky bonds

International Nuclear Information System (INIS)

Xu, Wen-Sheng; Freed, Karl F.

2016-01-01

Telechelic polymers are chain macromolecules that may self-assemble through the association of their two mono-functional end groups (called “stickers”). A deep understanding of the relation between microscopic molecular details and the macroscopic physical properties of telechelic polymers is important in guiding the rational design of telechelic polymer materials with desired properties. The lattice cluster theory (LCT) for strongly interacting, self-assembling telechelic polymers provides a theoretical tool that enables establishing the connections between important microscopic molecular details of self-assembling polymers and their bulk thermodynamics. The original LCT for self-assembly of telechelic polymers considers a model of fully flexible linear chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)], while our recent work introduces a significant improvement to the LCT by including a description of chain semiflexibility for the bonds within each individual telechelic chain [W.-S. Xu and K. F. Freed, J. Chem. Phys. 143, 024901 (2015)], but the physically associative (or called “sticky”) bonds between the ends of the telechelics are left as fully flexible. Motivated by the ubiquitous presence of steric constraints on the association of real telechelic polymers that impart an additional degree of bond stiffness (or rigidity), the present paper further extends the LCT to permit the sticky bonds to be semiflexible but to have a stiffness differing from that within each telechelic chain. An analytical expression for the Helmholtz free energy is provided for this model of linear telechelic polymer melts, and illustrative calculations demonstrate the significant influence of the stiffness of the sticky bonds on the self-assembly and thermodynamics of telechelic polymers. A brief discussion is also provided for the impact of self-assembly on glass-formation by combining the LCT description for this extended model of telechelic polymers with

Irrational Rationality of Terrorism

Directory of Open Access Journals (Sweden)

Robert Nalbandov

2013-12-01

Full Text Available The present article deals with the ontological problem of applying the rational choice frameworks to the study of terrorism. It testing the application of the rational choice to the “old” (before the end of the Cold War and the “new” (after the end of the Cold War terrorisms. It starts with analyzing the fundamentals of rationality and applies it at two levels: the individual (actors and group (collective via two outlooks: tactical (short-term and strategic (long-term. The main argument of the article is that while the “old” terrorism can be explained by the rational choice theory its “new” version represents a substantial departure from rationality.

Appendix to rationally designing of machine tools for example of universal lathe

Directory of Open Access Journals (Sweden)

Pejović Branko B.

2015-01-01

Full Text Available In this paper, for the universal machine tool for turning and function of the thrust of the cutting speed for blasting area efficiency and stability of the tool and sectional filings. These dependencies were used to determine the main characteristics of the optimal and maximum operating power equipment. Based on this, an analysis of the increase in operating power equipment typical cases in order to adapt to the new needs of exploitation properties and improve productivity. Using the previous analysis, it was determined the best solution in terms of the rational design of machines, by ensuring the simultaneous use of the main features on the basis of increase in speed with the use of tools and higher stability. In order to better display problems, an analysis of the appropriate diagrams P-V and V-D. On a typical example of the manufacturing practice at the end of the work, we demonstrate improvement of exploitation characteristics of a universal machine through appropriate calculations in terms of new needs adjustment feature, where it is expected that the reconstruction of the smallest machines.

Biomimetic materials and design: biointerfacial strategies, tissue engineering, and targeted drug delivery

National Research Council Canada - National Science Library

Dillow, Angela K; Lowman, Anthony M

2002-01-01

... significant immune responses or toxicity issues- became the focus of the rational decision for materials to be used within the body. Biodegradable polymers also became (and still are) a focus of much research in the area of biomaterials science. Using biodegradable materials, the goal is to produce polymers with appropriate mechanical properties that de...

Lying for Strategic Advantage: Rational and Boundedly Rational Misrepresentation of Intentions

OpenAIRE

Crawford, Vincent P.

2001-01-01

Starting from Hendricks and McAfee's (2000) example of the Allies' decision to feint at Calais and attack at Normandy on D-Day, this paper models misrepresentation of intentions to competitors or enemies. Allowing for the possibility of bounded strategic rationality and rational players' responses to it yields a sensible account of lying via costless, noiseless messages. In many cases the model has generically unique pure-strategy sequential equilibria, in which rational players exploit bound...

Rational design of nanoparticles towards targeting antigen-presenting cells and improved T cell priming.

Science.gov (United States)

Zupančič, Eva; Curato, Caterina; Paisana, Maria; Rodrigues, Catarina; Porat, Ziv; Viana, Ana S; Afonso, Carlos A M; Pinto, João; Gaspar, Rogério; Moreira, João N; Satchi-Fainaro, Ronit; Jung, Steffen; Florindo, Helena F

2017-07-28

Vaccination is a promising strategy to trigger and boost immune responses against cancer or infectious disease. We have designed, synthesized and characterized aliphatic-polyester (poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) to investigate how the nature of protein association (adsorbed versus entrapped) and polymer/surfactant concentrations impact on the generation and modulation of antigen-specific immune responses. The ability of the NP formulations to target dendritic cells (DC), be internalized and activate the T cells was characterized and optimized in vitro and in vivo using markers of DC activation and co-stimulatory molecules. Ovalbumin (OVA) was used as a model antigen in combination with the engraftment of CD4 + and CD8 + T cells, carrying a transgenic OVA-responding T cell receptor (TCR), to trace and characterize the activation of antigen-specific CD4 + and CD8 + lymph node T cells upon NP vaccination. Accordingly, the phenotype and frequency of immune cell stimulation induced by the NP loaded with OVA, isolated or in combination with synthetic unmethylated cytosine-phosphate-guanine (CpG) oligodeoxynucleotide (ODN) motifs, were characterized. DC-NP interactions increased with incubation time, presenting internalization values between 50 and 60% and 30-40%, in vitro and in vivo, respectively. Interestingly, animal immunization with antigen-adsorbed NP up-regulated major histocompatibility complex (MHC) class II (MHCII), while NP entrapping the antigen up-regulated MHCI, suggesting a more efficient cross-presentation. On the other hand, rather surprisingly, the surfactant used in the NP formulation had a major impact on the activation of antigen presenting cells (APC). In fact, DC collected from lymph nodes of animals immunized with NP prepared using poly(vinil alcohol) (PVA), as a surfactant, expressed significantly higher levels of CD86, MHCI and MHCII. In addition, those NP prepared with PVA and co-entrapping OVA and the toll

Towards a rational design of commercial maltodextrins : a mechanistic approach

NARCIS (Netherlands)

Marchal, L.M.

1999-01-01

Industrially produced starch is used for various applications mainly in the food, paper and textile industries. A considerable quantity of this starch is modified (chemically, physically, or enzymatically) before use. The most important modifications are polymer degradation, oxidation,

Inorganic polymers and materials. Final report

Energy Technology Data Exchange (ETDEWEB)

Sneddon, Larry G.

2001-01-01

This DOE-sponsored project was focused on the design, synthesis, characterization, and applications of new types of boron and silicon polymers with a goal of attaining processable precursors to advanced ceramic materials of technological importance. This work demonstrated a viable design strategy for the systematic formation of polymeric precursors to ceramics based on the controlled functionalization of preformed polymers with pendant groups of suitable compositions and crosslinking properties. Both the new dipentylamine-polyborazylene and pinacolborane-hydridopolysilazane polymers, unlike the parent polyborazylene and other polyborosilazanes, are stable as melts and can be easily spun into polymer fibers. Subsequent pyrolyses of these polymer fibers then provide excellent routes to BN and SiNCB ceramic fibers. The ease of synthesis of both polymer systems suggests new hybrid polymers with a range of substituents appended to polyborazylene or polysilazane backbones, as well as other types of preceramic polymers, should now be readily achieved, thereby allowing even greater control over polymer and ceramic properties. This control should now enable the systematic tailoring of the polymers and derived ceramics for use in different technological applications. Other major recent achievements include the development of new types of metal-catalyzed methods needed for the polymerization and modification of inorganic monomers and polymers, and the modification studies of polyvinylsiloxane and related polymers with substituents that enable the formation of single source precursors to high-strength, sintered SiC ceramics.

A Functional Monomer Is Not Enough: Principal Component Analysis of the Influence of Template Complexation in Pre-Polymerization Mixtures on Imprinted Polymer Recognition and Morphology

Directory of Open Access Journals (Sweden)

Kerstin Golker

2014-11-01

Full Text Available In this report, principal component analysis (PCA has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA-crosslinked polymers had either methacrylic acid (MAA or methyl methacrylate (MMA as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

Recovery of Waterflood Residual Oil Using Alkali, Surfactant and Polymer Slugs in Radial Cores Récupération d'huile résiduelle par injection d'eau améliorée de produits alcalins, de tensio-actifs et de polymères dans des carottes radiales

Directory of Open Access Journals (Sweden)

Nasr-El-Din H. A.

2006-11-01

Full Text Available An experimental study has been conducted to examine mobilization and recovery of waterflood residual oil in radial cores. Alkali, surfactant, and polymer slugs of various compositions, sizes and sequences were tested. Core flood experiments were conducted with unfired radial Berea sandstone disks at a flow rate of 8 cm3/h. David Lloydminster crude oil (total acid number of 0. 45 mg KOH/g oil was used. The results of the present work showed that the composition and sequence of the injected chemical slug play an important role in mobilization and recovery of residual oil. For slugs lacking either mobility control, or low interfacial tension, no oil bank was formed and tertiary oil recovery was less than 20% Sor. A significant oil bank and tertiary oil recovery up to 70 % Sor were obtained with slugs having mobility control and low interfacial tension. However, maximum oil cut, incre-mental oil recovery and surfactant propagation were found to be functions of the alkali content in the slug. The incremental oil recovery, oil cut and slug injectivity greatly improved as the alkali concentration (sodium carbonate in the combined slug was increased. A slight delay in surfactant breakthrough and a significantly slower rate of surfactant propagation were observed at higher sodium carbonate concentrations. Une étude expérimentale ayant pour but d'examiner la mobilisation et la récupération assistée d'huile résiduelle, à la suite d'un déplacement par l'eau en milieu poreux, a été conduite. Des bouchons de produit alcalin, de surfactant et de polymère, ayant des compositions, grosseurs et séquences d'injection variées, furent essayés. Les déplacements en milieu poreux furent conduits en utilisant des carottes de grès berea (non traités à haute température et un débit de 8,0 cm3/h. Pour ce faire, on utilisa de l'huile de David Lloydminster (ayant un nombre acide de 0,45 mg KOH/g d'huile. Les résultats de ce travail ont démontré que la

Polymer materials basic research needs for energy applications

Energy Technology Data Exchange (ETDEWEB)

Macknight, W.J.; Baer, E.; Nelson, R.D. (eds.)

1978-08-01

The larger field covered in the workshop consists of (1) synthesis and characterization, (2) physical chemistry, (3) physics, and (4) engineering. Polymeric materials are properly regarded as new materials in their own right, not as replacements for existing materials. As such they need to be studied to understand the properties which are unique to them by virtue of their particular molecular structures. Technological applications will rationally follow from such studies. It is the objective of this report to point out basic research needs in polymer materials related to energy. The development of sophisticated instrumentation makes the task of molecular characterization possible on a level hitherto unattainable. Many of these instruments because of their size and complexity must of necessity be located at the DOE National Laboratories. The importance of personnel trained in the polymer field located at these facilities is emphasized. In the past there has been relatively little concerted polymer research within the energy community. This report attempts to describe the present situation and point out some needs and future research directions. (GHT)

Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors

KAUST Repository

Nielsen, Christian B.

2016-07-22

The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous envi-ronment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially availa-ble conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, elec-trochromic properties, operational voltage and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT based devices, and show stability under aqueous oper-ation without the need for formulation additives and cross-linkers.

Mussel-inspired Fluoro-Polydopamine Functionalization of Titanium Dioxide Nanowires for Polymer Nanocomposites with Significantly Enhanced Energy Storage Capability

Science.gov (United States)

Wang, Guanyao; Huang, Xingyi; Jiang, Pingkai

2017-01-01

High-dielectric-constant polymer nanocomposites are demonstrated to show great promise as energy storage materials. However, the large electrical mismatch and incompatibility between nanofillers and polymer matrix usually give rise to significantly reduced breakdown strength and weak energy storage capability. Therefore, rational selection and elaborate functionalization of nanofillers to optimize the performance of polymer nanocomposites are vital. Herein, inspired by adhesive proteins in mussels, a facile modification by fluoro-polydopamine is employed to reinforce the compatibility of TiO2 nanowires in the fluoropolymer matrix. The loading of 2.5 vol % f-DOPA@TiO2 NWs leads to an ultrahigh discharged energy density of 11.48 J cm−3 at 530 MV m−1, more than three times of commercial biaxial-oriented polypropylene (BOPP, 3.56 J cm−3 at 600 MV m−1). A gratifying high energy density of 9.12 J cm−3 has also been obtained with nanofiller loading as high as 15 vol % at 360 MV m−1, which is nearly double to that of pure P(VDF-HFP) (4.76 J cm−3 at 360 MV m−1). This splendid energy storage capability seems to rival or exceed most of previously reported nano-TiO2 based nanocomposites. The methods presented here provide deep insights into the design of polymer nanocomposites for energy storage applications. PMID:28225047

Mussel-inspired Fluoro-Polydopamine Functionalization of Titanium Dioxide Nanowires for Polymer Nanocomposites with Significantly Enhanced Energy Storage Capability

Science.gov (United States)

Wang, Guanyao; Huang, Xingyi; Jiang, Pingkai

2017-02-01

High-dielectric-constant polymer nanocomposites are demonstrated to show great promise as energy storage materials. However, the large electrical mismatch and incompatibility between nanofillers and polymer matrix usually give rise to significantly reduced breakdown strength and weak energy storage capability. Therefore, rational selection and elaborate functionalization of nanofillers to optimize the performance of polymer nanocomposites are vital. Herein, inspired by adhesive proteins in mussels, a facile modification by fluoro-polydopamine is employed to reinforce the compatibility of TiO2 nanowires in the fluoropolymer matrix. The loading of 2.5 vol % f-DOPA@TiO2 NWs leads to an ultrahigh discharged energy density of 11.48 J cm-3 at 530 MV m-1, more than three times of commercial biaxial-oriented polypropylene (BOPP, 3.56 J cm-3 at 600 MV m-1). A gratifying high energy density of 9.12 J cm-3 has also been obtained with nanofiller loading as high as 15 vol % at 360 MV m-1, which is nearly double to that of pure P(VDF-HFP) (4.76 J cm-3 at 360 MV m-1). This splendid energy storage capability seems to rival or exceed most of previously reported nano-TiO2 based nanocomposites. The methods presented here provide deep insights into the design of polymer nanocomposites for energy storage applications.

Nanoparticles Stabilize Thin Polymer Films: A Fundamental Study to Understand the Phenomenon

Energy Technology Data Exchange (ETDEWEB)

Michael E. Mackay

2009-03-04

A new understanding of thermodynamics at the nanoscale resulted in a recently discovered first order phase transition that nanoparticles in a polymer film will all segregate to the supporting substrate. This is an unusual phase transition that was predicted using a modeling technique developed at Sandia National Laboratories and required the equivalent of many computational years on one computer. This project is a collaboration between Prof. Michael Mackay's group and Dr. Amalie Frischknecht (Sandia National Laboratories) where experimental observation and theoretical rationalization and prediction are brought together. Other discoveries were that this phase transition could be avoided by changing the nanoparticle properties yielding control of the assembly process at the nanoscale. In fact, the nanoparticles could be made to assemble to the supporting substrate, to the air interface or not assemble at all within a thin polymer film of order 100 nm in thickness. However, when the assembly process is present it is so robust that it is possible to make rough liquid films at the nanoscale due to nanoparticles assembling around three-dimensional objects. From this knowledge we are able to design and manufacture new coatings with particular emphasis on polymer-based solar cells. Careful control of the morphology at the nanoscale is expected to provide more efficient devices since the physics of these systems is dictated at this length scale and assembly of nanoparticles to various interfaces is critical to operation.

Determinants of Actor Rationality

DEFF Research Database (Denmark)

Ellegaard, Chris

Industrial companies must exercise influence on their suppliers (or supplier actors). Actor rationality is a central theme connected to this management task. In this article, relevant literature is studied with the purpose of shedding light on determinants of actor rationality. Two buyer-supplier...... relations are investigated in a multiple case study, leading to the proposal of various additional factors that determine and shape actor rationality. Moreover a conceptual model of rationality determinants in the buyer-supplier relation is proposed, a model that may help supply managers analyse...

Two Concepts of Rationality

Directory of Open Access Journals (Sweden)

Danny Frederick

2010-02-01

Full Text Available The dominant tradition in Western philosophy sees rationality as dictating. Thus rationality may require that we believe the best explanation and simple conceptual truths and that we infer in accordance with evident rules of inference. I argue that, given what we know about the growth of knowledge, this authoritarian concept of rationality leads to absurdities and should be abandoned. I then outline a libertarian concept of rationality, derived from Popper, which eschews the dictates and which sees a rational agent as one who questions, criticises, conjectures and experiments. I argue that, while the libertarian approach escapes the absurdities of the authoritarian, it requires two significant developments and an important clarification to be made fully consistent with itself.

Rationality and institutions : an inquiry into the normative implications of rational choice theory

OpenAIRE

Engelen, Bart

2007-01-01

I aim to analyze in this dissertation what a desirable basic institutional structure looks like from the perspective of rationality. While the main topic is thus normative in nature, I start by clarifying in the first part what the notion of rationality exactly entails. I do so by focusing explicitly on the economic conception of rationality, according to which a rational individual is motivated to serve his self-interest on the basis of cost-benefit calculations. Such a Homo Economicus is ch...

Rational Behavior Training: A Seven Lesson Sequence for Teaching Rational Behavior Skills to Students with Social and Emotional Disabilities.

Science.gov (United States)

Patton, Patricia Lucey

This seven lesson curriculum sequence is designed to help teachers teach principles of Rational Behavior Training (RBT) which targets thinking behaviors, feeling behaviors, and behavioral responses to the environment. The program is appropriate for students with social and emotional disabilities and also develops reading, writing, spelling,…

Novel salicylazo polymers for colon drug delivery: dissolving polymers by means of bacterial degradation.

Science.gov (United States)

Saphier, Sigal; Karton, Yishai

2010-02-01

Novel azo polymers were prepared for colonic drug delivery with a release mechanism based on structural features of azo derivatives designed for rapid bacterial degradation leading to soluble polymers. Two Salicylazo derivatives were prepared and conjugated as side chains at different ratios to methacrylic acid-methyl methacrylate copolymers (Eudragits). The azo compounds were designed to have a hydrophilic and a hydrophobic part on opposite sides of the azo bond. Upon reduction of the azo bonds, the hydrophobic part is released, resulting in a more water soluble polymer. The solubility of the polymeric films was studied relative to Eudragit S known to dissolve toward the end of the small intestine. One of the two azo derivatives prepared gave rise to polymers, which showed reduced solubility relative to Eudragit S. These polymers were subjected to reduction tests in anaerobic rat cecal suspensions by following the release of the hydrophobic product. Reduction rate was found to be rapid, comparable to that of Sulfasalazine. Studies on the azopolymeric films in anaerobic rat cecal suspensions, showed that these polymers dissolve faster than in sterilized suspensions. Solid dosage forms may be coated with these polymers to provide an efficient delivery system to the colon with a rapid release mechanism. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association.

Design and analysis of dual-resonant filters in visible and infra-red region based on polymer LPWG

Science.gov (United States)

Sharma, Mukesh; Kushwaha, Aniruddha Singh; Pal, Suchandan

2013-01-01

Long-period waveguide gratings (LPWGs), by using a SU-8 polymer-based channel waveguide along with NOA61 optical epoxy coated upper- and lower-cladding, are designed and theoretical analyzed. Grating period of ~ 68μm is considered with optimized grating tooth-heights, so that the transmission spectra of the gratings show strong rejection bands both at visible (450 - 460 nm) and infrared (1530 - 1540 nm) wavelength regions. Phase-matching graphs are studied in order to observe the change in resonance wavelength of the grating with the variation of waveguide parameters. LPWG-based band pass filter are also designed and analyzed by considering the same set of polymer materials. Further, temperature sensitivity of these LPWGs is analyzed theoretically. These types of waveguide gratingbased filters can widely be used for visible and infrared wavelength sensing applications.

Rationing medical education.

African Journals Online (AJOL)

This paper discussed the pros and cons of the application of rationing to medical education and the different ... Different types of rationing exist in healthcare professional education. ... state-of-the-art resources, technology and tutors con-.

Cellobiose dehydrogenase entrapped within specifically designed Os-complex modified electrodeposition polymers as potential anodes for biofuel cells

International Nuclear Information System (INIS)

Shao, Minling; Guschin, Dmitrii A.; Kawah, Zahma; Beyl, Yvonne; Stoica, Leonard; Ludwig, Roland; Schuhmann, Wolfgang; Chen, Xingxing

2014-01-01

Electron-transfer pathways between cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH) and the related flavodehydrogenase domain (FAD-MtCDH) and electrodes were evaluated using specifically designed Os-complex modified electrodeposition paints (EDPs). The properties of the Os-complex modified EDPs were varied by variation of the monomer composition, the coordination sphere of the polymer-bound Os-complexes, and the length and flexibility of the spacer chain between Os complex and polymer backbone. The MtCDH-to-EDP weight ratio, the pH value, as well as the operational temperature have been optimized

The new designs of diamond drill bits for composite polymers tooling

Directory of Open Access Journals (Sweden)

Ruslan Yu. Melentiev

2015-12-01

Full Text Available The author explores the drilling operation of some new engineering materials such as carbon fiber reinforced plastics (CFRP and other polymers that have an anisotropic structure, high-strength and elastic properties combined with low heat endurance. Such combination of properties makes impossible the simple transfer of the existing technologies for classic materials working to considered new class. At the same time, the existing tools cannot assure the specified quality of tooled products at the current productivity and tool life. Aim: The aim of this research is to increase the process efficiency of diamond drilling in composite polymers by developing the new designs of diamond drill bits. Materials and Methods: One of the most promising directions to solve this problem is the diamond coated abrasive type tool. This paper addresses and classifies the existing types of diamond drill bits according to their application and operation. The literature data analysis of known disadvantages during drilling operation, the quality of surface and joining face was performed. Results: The experimental researches of the author prove the negative meaning of the already known but kept out fact – the drill core blocking. The most important factors and structural features affecting the CFRP drilling process are revealed. The accounting of these factors allowed creating the set of unique designs of diamond drill bits for different purposes. The presented patented models has different allowance distribution schemes and cutting forces, thus satisfy the mechanical requirements of quality, productivity, tool life and hole geometry in the tooling of the specified material class.

Rational preparation of dibenzothiophene-imprinted polymers by surface imprinting technique combined with atom transfer radical polymerization

International Nuclear Information System (INIS)

Yang, Wenming; Liu, Lukuan; Zhou, Zhiping; Liu, Hong; Xie, Binze; Xu, Wanzhen

2013-01-01

A computational simulation method is introduced to simulate the dibenzothiophene-monomer pre-assembly system of molecular imprinted polymers. The interaction type and intensity between dibenzothiophene and monomer are discussed from the binding energy and spatial position distribution. The simulation and analysis results indicate that the amount of the function monomer is not the more the better in preparing molecular imprinted polymers. Based on the above results, a novel dibenzothiophene-imprinted polymers with the favorable specific adsorption effect was prepared by surface imprinting technique combined with atom transfer radical polymerization. This combined technologies are used for preparing a desulfurization adsorbent for the first time. Various measures were selected to characterize the structure and morphology of the prepared adsorbent. The characterization results show that the adsorbent has suitable features for further adsorption process. A series of static adsorption experiments were conducted to analyze its adsorption performance. The adsorption process follows Elovich model by the kinetic analysis and Sips equation by the isothermal analysis. The approach we described will provide another opportunity in the deep desulfurization field.

Brush-Like Polymers: New Design Platforms for Soft, Dry Materials with Unique Property Relations

Science.gov (United States)

Daniel, William Francis McKemie, Jr.

Elastomers represent a unique class of engineering materials due to their light weight, low cost, and desirable combination of softness (105 -107 Pa) and large extensibilities (up to 1000%). Despite these advantages, there exist applications that require many times softer modulus, greater extensibility, and stronger strain hardening for the purpose of mimicking the mechanical properties of systems such as biological tissues. Until recently, only liquid-filled gels were suitable materials for such applications, including soft robotics and implants. A considerable amount of work has been done to create gels with superior properties, but despite unique strengths they also suffer from unique weaknesses. This class of material displays fundamental limitations in the form of heterogeneous structures, solvent loss and phase transitions at extreme temperatures, and loss of liquid fraction upon high deformations. In gels the solvent fraction also introduces a large solvent/polymer interaction parameter which must be carefully considered when designing the final mechanical properties. These energetic considerations further exaggerate the capacity for inconstant mechanical properties caused by fluctuations of the solvent fraction. In order to overcome these weaknesses, a new platform for single component materials with low modulus (Standard networks have one major control factor outside of chemistry, the network stand length. Brush-like architectures are created from long strands with regularly grafted side chains creating three characteristic length scales which may be independently manipulated. In collaboration with M. Rubinstein, we have utilized bottlebrush polymer architectures (a densely grafted brush-like polymer) to experimentally verify theoretical predictions of disentangled bottlebrush melts. By attaching well-defined side chains onto long polymer backbones, individual polymer strands are separated in space (similar to dilution with solvent) accompanied by a

Designing Polymer Blends Through Modeling and Simulation

National Research Council Canada - National Science Library

Balazs, Anna

2001-01-01

...) of clay sheets in polymer melts. In addition, we determined how the coupling between phase separation and wetting interactions in polymeric composites effects the structural evolution and phase behavior of the material...

Rationality problem for algebraic tori

CERN Document Server

Hoshi, Akinari

2017-01-01

The authors give the complete stably rational classification of algebraic tori of dimensions 4 and 5 over a field k. In particular, the stably rational classification of norm one tori whose Chevalley modules are of rank 4 and 5 is given. The authors show that there exist exactly 487 (resp. 7, resp. 216) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension 4, and there exist exactly 3051 (resp. 25, resp. 3003) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension 5. The authors make a procedure to compute a flabby resolution of a G-lattice effectively by using the computer algebra system GAP. Some algorithms may determine whether the flabby class of a G-lattice is invertible (resp. zero) or not. Using the algorithms, the suthors determine all the flabby and coflabby G-lattices of rank up to 6 and verify that they are stably permutation. The authors also show that the Krull-Schmidt theorem for G-...

Influence of relaxation processes in polymers on energy transfer by triplet levels

International Nuclear Information System (INIS)

Ibraev, N.Kh.; Zhunusbekov, A.M.

1996-01-01

Temperature influence on triplet-triplet (T-T) energy transfer between molecules of eosin and 3,4-benzopyrene is studied. Polyvenylbuteryl films have been used in capacity of polymer matrix. Calculation has being carried out on spectral-kinetic unit. It is revealed, that 3,4-benzopyrene triplets have been formed in polymer matrix after end of T-T energy transfer. These triplets join in a reaction of mixed triplet-triplet annihilation with non-blow out triplets of eosin and its sensitize slowed fluorescence (SF) of donor. This explains non-exponent character of eosin's dumping kinetics. Non-linear dependence of SF output ration to eosin phosphorescence output under presence of 3,4-benzopyrene molecules in film indicates on process of mixed annihilation. Fractal character of SF donor and acceptor has been evidenced about microscopical distribution of phosphor in polymer. 13 refs., 5 figs

Rational Approximations to Rational Models: Alternative Algorithms for Category Learning

Science.gov (United States)

Sanborn, Adam N.; Griffiths, Thomas L.; Navarro, Daniel J.

2010-01-01

Rational models of cognition typically consider the abstract computational problems posed by the environment, assuming that people are capable of optimally solving those problems. This differs from more traditional formal models of cognition, which focus on the psychological processes responsible for behavior. A basic challenge for rational models…

Adsorption of rationally designed "surf-tides" to a liquid-crystal interface.

Science.gov (United States)

Badami, Joseph V; Bernstein, Chaim; Maldarelli, Charles; Tu, Raymond S

2015-09-07

The interfacial adsorption of proteins in surfactant laden systems occurs both in nature and industrial processing, yet much of the fundamental behavior behind these systems is still not well understood. We report the development of a system that monitors optical transitions of a liquid-crystalline/aqueous interface to examine the dynamics of adsorption of two rationally designed model peptide molecules. The two molecules synthesized in this study were both designed to become surface-active upon folding and contain the same net charge of +3, but one of the peptides, K-2.5, has its three charges separated by 2.5 amino acids as compared to K-6.0, which has its three charges separated by 6 amino acids. Our study examines the roles that surfactant adsorption, peptide charge distribution and secondary structure have on the relative adsorption dynamics of these two models peptides onto a fluid/fluid interface. Using the optical detection of molecular adsorption and image analysis of these events, we obtain quantitative information about the dynamics as a function of the charge spacing and initial peptide concentration. We show that both peptides initially follow a diffusion-limited adsorption model onto the interface. Additionally, our results suggest that the K-6.0 peptides demonstrate enhanced adsorption kinetics, where the enhanced rates are a consequence of the well-folded adsorbed state and spatial distribution on the surface. These findings provide further insights into the role that charge spacing has on secondary structure and subsequently the dynamics of adsorption, while developing a versatile system capable of extracting quantitative information from a simple inexpensive optical system.

Understanding of the self- and co-assembly behavior of recombinant protein polymers : from design to implementation

NARCIS (Netherlands)

Golinska, M.D.

2014-01-01

A key part of the growing field of biomedical sciences deals with the development of new, controlled and biocompatible biomaterials. In this thesis we present results on the design, production, purification and characterization of stimuli responsive protein polymers that could ultimately be used

METHODOLOGICAL ASPECTS OF RATIONAL DESIGN FORMATION OF INFRASTRUCTURE OF AGRARIAN SECTOR OF UKRAINE

Directory of Open Access Journals (Sweden)

Ivan Korchynskyy

2016-11-01

Full Text Available Methodological aspects of formation of rational design of infrastructure of agrarian sector of Ukraine on the basis of the institutional approach and laws of architectonics are examined. It is shown that the agrarian sector of Ukraine is a complex socio-economic system, the formation and development of which is in the process of market transformation what is caused by institutional influences. In general the process of relations institutionalization imply their formalization and standardization, in other case the subject of public life could not predict the actions of other entities associated with him and ensure their cooperation. One of the specific characteristic of human society is formed institutional system that regulates behaviour. In the article the factors of influence on the conduct of being in charge subjects are considered in the conditions of development of market economy. The special attention is spared the institutional factors of the economy growing. Methodology. The meaning of “agricultural field” and “infrastructure” and their mutual consistency is classified. As the scientific method, the institutional approach of principles of architectonics has been used, which allowed to justify the creation of a rational approach to the design of infrastructure in agrarian sector as a whole on the basis, relation and interdependence of its elements, based on the fundamental laws of architectonics (law of equilibrium, law of the golden mean structuring. The article demonstrates a necessary of the choice of a theory of institutionalism as the main methodological basis for the study of the process of innovation development of economic system of Ukraine. It is determined that the inefficient activities of institutions in Ukraine are the main cause of the low level of innovation, which has a negative impact on the development of the economy as a whole. Results. Research points on new aspects of infrastructure as a part of the entire

Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

International Nuclear Information System (INIS)

Rahbar, Mona; Gray, Bonnie L; Shannon, Lesley

2016-01-01

We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min −1 for pressures up to 9.65 kPa in microfluidic channels 200 μ m wide and 200 μ m deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min −1 with larger microfluidic channels of up to 1 mm wide and 500 μ m deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices. (paper)

Rational design of protamine nanocapsules as antigen delivery carriers.

Science.gov (United States)

González-Aramundiz, José Vicente; Presas, Elena; Dalmau-Mena, Inmaculada; Martínez-Pulgarín, Susana; Alonso, Covadonga; Escribano, José M; Alonso, María J; Csaba, Noemi Stefánia

2017-01-10

Current challenges in global immunization indicate the demand for new delivery strategies, which could be applied to the development of new vaccines against emerging diseases, as well as to improve safety and efficacy of currently existing vaccine formulations. Here, we report a novel antigen nanocarrier consisting of an oily core and a protamine shell, further stabilized with pegylated surfactants. These nanocarriers, named protamine nanocapsules, were rationally designed to promote the intracellular delivery of antigens to immunocompetent cells and to trigger an efficient and long-lasting immune response. Protamine nanocapsules have nanometric size, positive zeta potential and high association capacity for H1N1 influenza hemagglutinin, a protein that was used here as a model antigen. The new formulation shows an attractive stability profile both, as an aqueous suspension or a freeze-dried powder formulation. In vitro studies showed that protamine nanocapsules were efficiently internalized by macrophages without eliciting significant toxicity. In vivo studies indicate that antigen-loaded nanocapsules trigger immune responses comparable to those achieved with alum, even when using significantly lower antigen doses, thus indicating their adjuvant properties. These promising in vivo data, alongside with their versatility for the loading of different antigens and oily immunomodulators and their excellent stability profile, make these nanocapsules a promising platform for the delivery of antigens. Protamine sulphate (PubChem SID: 7849283), Sodium Cholate (PubChem CID: 23668194), Miglyol (PubChem CID: 53471835), α tocopherol (PubChem CID: 14985), Tween® 20(PubChem CID: 443314), Tween® 80(PubChem CID: 5281955), TPGS (PubChem CID: 71406). Copyright © 2016 Elsevier B.V. All rights reserved.

Rationally Designed TLR4 Ligands for Vaccine Adjuvant Discovery

Directory of Open Access Journals (Sweden)

Kelsey A. Gregg

2017-05-01

Full Text Available Adjuvant properties of bacterial cell wall components like MPLA (monophosphoryl lipid A are well described and have gained FDA approval for use in vaccines such as Cervarix. MPLA is the product of chemically modified lipooligosaccharide (LOS, altered to diminish toxic proinflammatory effects while retaining adequate immunogenicity. Despite the virtually unlimited number of potential sources among bacterial strains, the number of useable compounds within this promising class of adjuvants are few. We have developed bacterial enzymatic combinatorial chemistry (BECC as a method to generate rationally designed, functionally diverse lipid A. BECC removes endogenous or introduces exogenous lipid A-modifying enzymes to bacteria, effectively reprogramming the lipid A biosynthetic pathway. In this study, BECC is applied within an avirulent strain of Yersinia pestis to develop structurally distinct LOS molecules that elicit differential Toll-like receptor 4 (TLR4 activation. Using reporter cell lines that measure NF-κB activation, BECC-derived molecules were screened for the ability to induce a lower proinflammatory response than Escherichia coli LOS. Their structures exhibit varied, dose-dependent, TLR4-driven NF-κB activation with both human and mouse TLR4 complexes. Additional cytokine secretion screening identified molecules that induce levels of tumor necrosis factor alpha (TNF-α and interleukin-8 (IL-8 comparable to the levels induced by phosphorylated hexa-acyl disaccharide (PHAD. The lead candidates demonstrated potent immunostimulation in mouse splenocytes, human primary blood mononuclear cells (PBMCs, and human monocyte-derived dendritic cells (DCs. This newly described system allows directed programming of lipid A synthesis and has the potential to generate a diverse array of TLR4 agonist candidates.

High performance all polymer solar cells fabricated via non-halogenated solvents (Presentation Recording)

Science.gov (United States)

Zhou, Yan; Bao, Zhenan

2015-10-01

The performance of organic solar cells consisting of a donor/acceptor bulk heterojunction (BHJ) has rapidly improved over the past few years.1. Major efforts have been focused on developing a variety of donor materials to gain access to different regions of the solar spectrum as well as to improve carrier transport properties.2 On the other hand, the most utilized acceptors are still restricted to the fullerene family, which includes PC61BM, PC71BM and ICBA.2b, 3 All-polymer solar cells, consisting of polymers for both the donor and acceptor, gained significantly increased interests recently, because of their ease of solution processing, potentially low cost, versatility in molecular design, and their potential for good chemical and morphological stability due to entanglement of polymers. Unlike small molecular fullerene acceptors, polymer acceptors can benefit from the high mobility of intra-chain charge transport and exciton generation by both donor and acceptor. Despite extensive efforts on all-polymer solar cells in the past decade, the fundamental understanding of all-polymer solar cells is still in its inceptive stage regarding both the materials chemistry and structure physics.4 Thus, rational design rules must be utilized to enable fundamental materials understanding of the all polymer solar cells. We report high performance all-polymer solar cells employing polymeric donors based on isoindigo and acceptor based on perylenedicarboximide. The phase separation domain length scale correlates well with the JSC and is found to be highly sensitive to the aromatic co-monomer structures used in the crystalline donor polymers. With the PS polymer side chain engineering, the phase separation domain length scale decreased by more than 45%. The PCE and JSC of the devices increased accordingly by more than 20%. A JSC as high as 10.0 mA cm-2 is obtained with the donor-acceptor pair despite of a low LUMO-LUMO energy offset of less than 0.1 eV. All the factors such as

Rational design of organic electro-optic materials

CERN Document Server

Dalton, L R

2003-01-01

Quantum mechanical calculations are used to optimize the molecular first hyperpolarizability of organic chromophores and statistical mechanical calculations are used to optimize the translation of molecular hyperpolarizability to macroscopic electro-optic activity (to values of greater than 100 pm V sup - sup 1 at telecommunications wavelengths). Macroscopic material architectures are implemented exploiting new concepts in nanoscale architectural engineering. Multi-chromophore-containing dendrimers and dendronized polymers not only permit optimization of electro-optic activity but also of auxiliary properties including optical loss (both absorption and scattering), thermal and photochemical stability and processability. New reactive ion etching and photolithographic techniques permit the fabrication of three-dimensional optical circuitry and the integration of that circuitry with semiconductor very-large-scale integration electronics and silica fibre optics. Electro-optic devices have been fabricated exploiti...

Laser micromachining of chemically altered polymers

Energy Technology Data Exchange (ETDEWEB)

Lippert, T.

1998-08-01

During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposals, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emissino lines, e.g. 351, 308 and 248 nm lines of excimer lasers. The authors show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are no redeposited ablation products or surface modifications of the polymer after ablation.

Polymer architecture and drug delivery.

Science.gov (United States)

Qiu, Li Yan; Bae, You Han

2006-01-01

Polymers occupy a major portion of materials used for controlled release formulations and drug-targeting systems because this class of materials presents seemingly endless diversity in topology and chemistry. This is a crucial advantage over other classes of materials to meet the ever-increasing requirements of new designs of drug delivery formulations. The polymer architecture (topology) describes the shape of a single polymer molecule. Every natural, seminatural, and synthetic polymer falls into one of categorized architectures: linear, graft, branched, cross-linked, block, star-shaped, and dendron/dendrimer topology. Although this topic spans a truly broad area in polymer science, this review introduces polymer architectures along with brief synthetic approaches for pharmaceutical scientists who are not familiar with polymer science, summarizes the characteristic properties of each architecture useful for drug delivery applications, and covers recent advances in drug delivery relevant to polymer architecture.

Optimal public rationing and price response.

Science.gov (United States)

Grassi, Simona; Ma, Ching-To Albert

2011-12-01

We study optimal public health care rationing and private sector price responses. Consumers differ in their wealth and illness severity (defined as treatment cost). Due to a limited budget, some consumers must be rationed. Rationed consumers may purchase from a monopolistic private market. We consider two information regimes. In the first, the public supplier rations consumers according to their wealth information (means testing). In equilibrium, the public supplier must ration both rich and poor consumers. Rationing some poor consumers implements price reduction in the private market. In the second information regime, the public supplier rations consumers according to consumers' wealth and cost information. In equilibrium, consumers are allocated the good if and only if their costs are below a threshold (cost effectiveness). Rationing based on cost results in higher equilibrium consumer surplus than rationing based on wealth. Copyright © 2011 Elsevier B.V. All rights reserved.

Approaches for Making High Performance Polymer Materials from Commodity Polymers

Institute of Scientific and Technical Information of China (English)

Xu Xi

2004-01-01

blending it with small amount of degraded PVC, fulfilling the idea of plasticizing PVC by itself.Through co-milling of PS and TiO2 with the pan-mill designed by our Lab, the co-milled PS/TiO2 is easier to process and has higher impact strength than that of the blended PS/TiO2.3. Stress induced reactions and irradiation processing technique were utilized for making polymer nanomaterials. PMMA microlatex, polyamiline nanoparticles, PBA/SiO2 nano-composite latex,ultra-fine PA6 filled PP blend, ultra-fine waste tire rubber (WTR) filled PP and Fe/PP nanocomposite were successfully prepared.4. The superstructure and properties of polymer might be improved through hydrogen bonding.Intermacromolecular complexation is a physical way to control the supermolecular structure of polymers at the molecular level and may be treated as a molecular design at higher structure level.A series of high performance polymer materials: PC/EAA complex, P(MMA-MAA)/PEO-LiClO4 complex, P(AN-AM-AA)/PVA complex, UV-irradiated PET/PVA complex and UV-irradiated HDPE/PA6 complex were prepared through hydrogen bonding.

Reduction of Polymer Adsorption on Reservoir Rocks Réduction de l'adsorption des polymères sur les roches réservoirs

Directory of Open Access Journals (Sweden)

Chauveteau G.

2006-11-01

Full Text Available The adsorption properties of polyacrylamides and xanthans on mineral surfaces carrying silanol and aluminol groups such as sand and kaolinite are described. The influence of the main parameters such as the nature of adsorption sites, surface charge, chemical structure and conformation of polymer and interactions of mono- and divalent ions with polymer and mineral surface has been investigated and interpreted. Some operating parameters in polymer flooding such as pH and salinity of injected solution, the nature of the polymer and its degree of ionicity were found to be determining factors from the adsorption level. The results give key elements for reducing adsorption by a proper choice of polymer nature and ionicity and of injection conditions. Les propriétés d'adsorption des polyacrylamides et des xanthanes sur des surfaces minérales portant des groupements silanols et aluminols comme le sable et la kaolinite ont été examinées. L'influence de différents paramètres est analysée : nature des sites d'adsorption, charge de surface, structure chimique et conformation du polymère, interactions des ions mono et divalents avec la surface. Il apparaît que le pH et la salinité de la solution injectée, la nature du polymère et, en particulier son degré d'ionicité, qui sont les paramètres opérationnels lors d'une injection de polymère destinée à augmenter le taux de récupération du pétrole, sont déterminants en ce qui concerne les niveaux d'adsorption. On en déduit les principaux moyens pour réduire l'adsorption dans un cas d'application donné.

White Polymer Light-Emitting Diodes Based on Exciplex Electroluminescence from Polymer Blends and a Single Polymer.

Science.gov (United States)

Liang, Junfei; Zhao, Sen; Jiang, Xiao-Fang; Guo, Ting; Yip, Hin-Lap; Ying, Lei; Huang, Fei; Yang, Wei; Cao, Yong

2016-03-09

In this Article, we designed and synthesized a series of polyfluorene derivatives, which consist of the electron-rich 4,4'-(9-alkyl-carbazole-3,6-diyl)bis(N,N-diphenylaniline) (TPA-Cz) in the side chain and the electron-deficient dibenzothiophene-5,5-dioxide (SO) unit in the main chain. The resulting copolymer PF-T25 that did not comprise the SO unit exhibited blue light-emission with the Commission Internationale de L'Eclairage coordinates of (0.16, 0.10). However, by physically blending PF-T25 with a blue light-emitting SO-based oligomer, a novel low-energy emission correlated to exciplex emerged due to the appropriate energy level alignment of TPA-Cz and the SO-based oligomers, which showed extended exciton lifetime as confirmed by time-resolved photoluminescent spectroscopy. The low-energy emission was also identified in copolymers consisting of SO unit in the main chain, which can effectively compensate for the high-energy emission to produce binary white light-emission. Polymer light-emitting diodes based on the exciplex-type single greenish-white polymer exhibit the peak luminous efficiency of 2.34 cd A(-1) and the maximum brightness of 12 410 cd m(-2), with Commission Internationale de L'Eclairage color coordinates (0.27, 0.39). The device based on such polymer showed much better electroluminescent stability than those based on blending films. These observations indicated that developing a single polymer with the generated exciplex emission can be a novel and effective molecular design strategy toward highly stable and efficient white polymer light-emitting diodes.

Exploring rationality in schizophrenia

DEFF Research Database (Denmark)

Revsbech, Rasmus; Mortensen, Erik Lykke; Owen, Gareth

2015-01-01

Background Empirical studies of rationality (syllogisms) in patients with schizophrenia have obtained different results. One study found that patients reason more logically if the syllogism is presented through an unusual content. Aims To explore syllogism-based rationality in schizophrenia. Meth...... differences became non-significant. Conclusions When taking intelligence and neuropsychological performance into account, patients with schizophrenia and controls perform similarly on syllogism tests of rationality.......Background Empirical studies of rationality (syllogisms) in patients with schizophrenia have obtained different results. One study found that patients reason more logically if the syllogism is presented through an unusual content. Aims To explore syllogism-based rationality in schizophrenia. Method...... Thirty-eight first-admitted patients with schizophrenia and 38 healthy controls solved 29 syllogisms that varied in presentation content (ordinary v. unusual) and validity (valid v. invalid). Statistical tests were made of unadjusted and adjusted group differences in models adjusting for intelligence...

Respect for rational autonomy.

Science.gov (United States)

Walker, Rebecca L

2009-12-01

The standard notion of autonomy in medical ethics does not require that autonomous choices not be irrational. The paper gives three examples of seemingly irrational patient choices and discusses how a rational autonomy analysis differs from the standard view. It then considers whether a switch to the rational autonomy view would lead to overriding more patient decisions but concludes that this should not be the case. Rather, a determination of whether individual patient decisions are autonomous is much less relevant than usually considered in determining whether health care providers must abide by these decisions. Furthermore, respect for rational autonomy entails strong positive requirements of respect for the autonomy of the person as a rational decision maker. The rationality view of autonomy is conceptually stronger than the standard view, allows for a more nuanced understanding of the practical moral calculus involved in respecting patient autonomy, and promotes positive respect for patient autonomy.

Influence of the Location of Attractive Polymer-Pore Interactions on Translocation Dynamics.

Science.gov (United States)

Ghosh, Bappa; Chaudhury, Srabanti

2018-01-11

We probe the influence of polymer-pore interactions on the translocation dynamics using Langevin dynamics simulations. We investigate the effect of the strength and location of the polymer-pore interaction using nanopores that are partially charged either at the entry or the exit or on both sides of the pore. We study the change in the translocation time as a function of the strength of the polymer-pore interaction for a given chain length and under the effect of an externally applied field. Under a moderate driving force and a chain length longer than the length of the pore, the translocation time shows a nonmonotonic increase with an increase in the attractive interaction. Also, an interaction on the cis side of the pore can increase the translocation probability. In the presence of an external field and a strong attractive force, the translocation time for shorter chains is independent of the polymer-pore interaction at the entry side of the pore, whereas an interaction on the trans side dominates the translocation process. Our simulation results are rationalized by a qualitative analysis of the free energy landscape for polymer translocation.

Embodying rationality

OpenAIRE

Mastrogiorgio, Antonio; Petracca, Enrico

2016-01-01

The current notions of bounded rationality in economics share distinctive features with Simon’s original notion, which still influences the theoretical and experimental research in the fields of choice, judgment, decision making, problem solving, and social cognition. All these notions of bounded rationality are in fact equally rooted in the information-processing approach to human cognition, expressing the view that reasoning is disembodied and that it can be reduced to the processing of abs...

Suicide: rationality and responsibility for life.

Science.gov (United States)

Ho, Angela Onkay

2014-03-01

Death by suicide is widely held as an undesirable outcome. Most Western countries place emphasis on patient autonomy, a concept of controversy in relation to suicide. This paper explores the tensions between patients' rights and many societies' overarching desire to prevent suicide, while clarifying the relations between mental disorders, mental capacity, and rational suicide. A literature search was conducted using search terms of suicide and ethics in the PubMed and LexisNexis Academic databases. Article titles and abstracts were reviewed and deemed relevant if the paper addressed topics of rational suicide, patient autonomy or rights, or responsibility for life. Further articles were found from reference lists and by suggestion from preliminary reviewers of this paper. Suicidal behaviour in a person cannot be reliably predicted, yet various associations and organizations have developed standards of care for managing patients exhibiting suicidal behaviour. The responsibility for preventing suicide tends to be placed on the treating clinician. In cases where a person is capable of making treatment decisions--uninfluenced by any mental disorder--there is growing interest in the concept of rational suicide. There is much debate about whether suicide can ever be rational. Designating suicide as an undesirable event that should never occur raises the debate of who is responsible for one's life and runs the risk of erroneously attributing blame for suicide. While upholding patient rights of autonomy in psychiatric care is laudable, cases of suicidality warrant a delicate consideration of clinical judgment, duty of care, and legal obligations.

Current collector design for closed-plenum polymer electrolyte membrane fuel cells

Science.gov (United States)

Daniels, F. A.; Attingre, C.; Kucernak, A. R.; Brett, D. J. L.

2014-03-01

This work presents a non-isothermal, single-phase, three-dimensional model of the effects of current collector geometry in a 5 cm2 closed-plenum polymer electrolyte membrane (PEM) fuel cell constructed using printed circuit boards (PCBs). Two geometries were considered in this study: parallel slot and circular hole designs. A computational fluid dynamics (CFD) package was used to account for species, momentum, charge and membrane water distribution within the cell for each design. The model shows that the cell can reach high current densities in the range of 0.8 A cm-2-1.2 A cm-2 at 0.45 V for both designs. The results indicate that the transport phenomena are significantly governed by the flow field plate design. A sensitivity analysis on the channel opening ratio shows that the parallel slot design with a 50% opening ratio shows the most promising performance due to better species, heat and charge distribution. Modelling and experimental analysis confirm that flooding inhibits performance, but the risk can be minimised by reducing the relative humidity of the cathode feed to 50%. Moreover, overheating is a potential problem due to the insulating effect of the PCB base layer and as such strategies should be implemented to combat its adverse effects.

Capital Requirements and Credit Rationing

OpenAIRE

Itai Agur

2010-01-01

This paper analyzes the trade-off between financial stability and credit rationing that arises when increasing capital requirements. It extends the Stiglitz-Weiss model of credit rationing to allow for bank default. Bank capital structure then matters for lending incentives. With default and rationing endogenous, optimal capital requirements can be analyzed. Introducing bank financiers, the paper also shows that uninsured funding raises the sensitivity of rationing to capital requirements. In...

Rationally designed, heterologous S. cerevisiae transcripts expose novel expression determinants

Science.gov (United States)

Ben-Yehezkel, Tuval; Atar, Shimshi; Zur, Hadas; Diament, Alon; Goz, Eli; Marx, Tzipy; Cohen, Rafael; Dana, Alexandra; Feldman, Anna; Shapiro, Ehud; Tuller, Tamir

2015-01-01

Deducing generic causal relations between RNA transcript features and protein expression profiles from endogenous gene expression data remains a major unsolved problem in biology. The analysis of gene expression from heterologous genes contributes significantly to solving this problem, but has been heavily biased toward the study of the effect of 5′ transcript regions and to prokaryotes. Here, we employ a synthetic biology driven approach that systematically differentiates the effect of different regions of the transcript on gene expression up to 240 nucleotides into the ORF. This enabled us to discover new causal effects between features in previously unexplored regions of transcripts, and gene expression in natural regimes. We rationally designed, constructed, and analyzed 383 gene variants of the viral HRSVgp04 gene ORF, with multiple synonymous mutations at key positions along the transcript in the eukaryote S. cerevisiae. Our results show that a few silent mutations at the 5′UTR can have a dramatic effect of up to 15 fold change on protein levels, and that even synonymous mutations in positions more than 120 nucleotides downstream from the ORF 5′end can modulate protein levels up to 160%–300%. We demonstrate that the correlation between protein levels and folding energy increases with the significance of the level of selection of the latter in endogenous genes, reinforcing the notion that selection for folding strength in different parts of the ORF is related to translation regulation. Our measured protein abundance correlates notably(correlation up to r = 0.62 (p=0.0013)) with mean relative codon decoding times, based on ribosomal densities (Ribo-Seq) in endogenous genes, supporting the conjecture that translation elongation and adaptation to the tRNA pool can modify protein levels in a causal/direct manner. This report provides an improved understanding of transcript evolution, design principles of gene expression regulation, and suggests simple

Polymer-Cement Composites Containing Waste Perlite Powder

Directory of Open Access Journals (Sweden)

Paweł Łukowski

2016-10-01

Full Text Available Polymer-cement composites (PCCs are materials in which the polymer and mineral binder create an interpenetrating network and co-operate, significantly improving the performance of the material. On the other hand, the need for the utilization of waste materials is a demand of sustainable construction. Various mineral powders, such as fly ash or blast-furnace slag, are successfully used for the production of cement and concrete. This paper deals with the use of perlite powder, which is a burdensome waste from the process of thermal expansion of the raw perlite, as a component of PCCs. The results of the testing of the mechanical properties of the composite and some microscopic observations are presented, indicating that there is a possibility to rationally and efficiently utilize waste perlite powder as a component of the PCC. This would lead to creating a new type of building material that successfully meets the requirements of sustainable construction.

Optical polymers for laser medical applications

Science.gov (United States)

Sultanova, Nina G.; Kasarova, Stefka N.; Nikolov, Ivan D.

2016-01-01

In medicine, optical polymers are used not only in ophthalmology but in many laser surgical, diagnostic and therapeutic systems. The application in lens design is determined by their refractive and dispersive properties in the considered spectral region. We have used different measuring techniques to obtain precise refractometric data in the visible and near-infrared spectral regions. Dispersive, thermal and other important optical characteristics of polymers have been studied. Design of a plastic achromatic objective, used in a surgical stereo-microscope at 1064 nm laser wavelength, is accomplished. Geometrical and wavefront aberrations are calculated. Another example of application of polymers is the designed all-mirror apochromatic micro-lens, intended for superluminescent diode fiber coupling in medical systems.

[Rationalization and rationing at the bedside. A normative and empirical status quo analysis].

Science.gov (United States)

Strech, D

2014-02-01

The topic of bedside rationing is increasingly discussed in Germany. Further need for clarification exists for the question how bedside rationing (e.g., in the area of overcare) can be justified despite coexistent inefficiencies. This paper outlines and analyses the relationship of waste avoidance and rationing from an ethical perspective. Empirical findings regarding the status quo of bedside rationing and rationalization are presented. These normative and empirical explorations will then be further specified regarding opportunities for future physician-driven activities to tackle overuse. The self-government partners in Germany should communicate more explicitly within their communities and to the public how and with which benchmarks they aim to reduce inefficient health care (overuse) in an appropriate manner. Physician-driven activities such as the "Choosing Wisely®" initiative in the USA could provide a first step to raise the awareness for overuse among physicians as well as in the public.

Molecular structure, vibrational spectra and quantum chemical MP2/DFT studies toward the rational design of hydroxyurea imprinted polymer

Science.gov (United States)

Prasad, Bhim Bali; Rai, Garima

2013-03-01

In this study, both experimental and theoretical vibrational spectra of template (hydroxyurea, HU), monomer (N-(4,6-bisacryloyl amino-[1,3,5] triazine-2-yl-)-acryl amide, TAT), and HU-TAT complexes were compared and these were respectively found to be in good agreement. Binding energies of HU, when complexed with different monomers, were computed using second order Moller Plesset theory (MP2) at 6-311++G(d,p) level both in the gas as well as solution phases. HU is an antineoplastic agent extensively being used in the treatment of polycythaemia Vera and thrombocythemia. It is also used to reduce the frequency of painful attacks in sickle cell anemia. It has antiretroviral property in disease like AIDS. All spectral characterizations were made using Density Functional Theory (DFT) at B3LYP employing 6-31+g(2d, 2p) basis set. The theoretical values for 13C and 1H NMR chemical shifts were found to be in accordance with the corresponding experimental values. Of all different monomers studied for the synthesis of molecularly imprinted polymer (MIP) systems, the monomer TAT (2 mol) was typically found to have a best binding score requisite for complexation with HU (1 mol) at the ground state.

Core/shell PLGA microspheres with controllable in vivo release profile via rational core phase design.

Science.gov (United States)

Yu, Meiling; Yao, Qing; Zhang, Yan; Chen, Huilin; He, Haibing; Zhang, Yu; Yin, Tian; Tang, Xing; Xu, Hui

2018-02-27

the microspheres prepared by various methods were mainly controlled by either the porosity inside the microspheres or the degradation of materials, which could, therefore, lead to different release behaviours. This results indicated great potential of the PLGA microsphere formulation as an injectable depot for controllable in vivo release profile via rational core phase design. Core/shell microspheres fabricated by modified double emulsification-solvent evaporation methods, with various inner phases, to obtain high loading drugs system, as well as appropriate release behaviours. Accordingly, control in vivo release profile via rational core phase design.

Ultralow Friction with Hydrophilic Polymer Brushes in Water as Segregated from Silicone Matrix

DEFF Research Database (Denmark)

Røn, Troels; Javakhishvili, Irakli; Hvilsted, Søren

2015-01-01

Lubrication is essential to minimize damage to underlying material and ensure low energy dissipation in biological and man-made mechanical sys- tems. Surface grafting of hydrophilic polymer brushes is a powerful means to render materials that are slippery in aqueous environments. However, presently......, as the hydrophilic polymer brushes are generated from an internal source of the material, excellent grafting stability and restoring capabilities are revealed even under harsh tribostress. The film can easily be applied to elastomers, metals, and ceramic substrates by spin- or drip-coating. Obtained sliding fric......- tion coefficients ( μ ) are 0.001–0.05 for soft contacts depending on substrate, load, counter surface, pH, and salinity. Between the two types of hydrophilic polymer chains, PAA shows far superior lubricity compared to PEG, which is rationalized by the larger reduction of total free energy...

Rational BRDF.

Science.gov (United States)

Pacanowski, Romain; Salazar Celis, Oliver; Schlick, Christophe; Granier, Xavier; Poulin, Pierre; Cuyt, Annie

2012-11-01

Over the last two decades, much effort has been devoted to accurately measuring Bidirectional Reflectance Distribution Functions (BRDFs) of real-world materials and to use efficiently the resulting data for rendering. Because of their large size, it is difficult to use directly measured BRDFs for real-time applications, and fitting the most sophisticated analytical BRDF models is still a complex task. In this paper, we introduce Rational BRDF, a general-purpose and efficient representation for arbitrary BRDFs, based on Rational Functions (RFs). Using an adapted parametrization, we demonstrate how Rational BRDFs offer 1) a more compact and efficient representation using low-degree RFs, 2) an accurate fitting of measured materials with guaranteed control of the residual error, and 3) efficient importance sampling by applying the same fitting process to determine the inverse of the Cumulative Distribution Function (CDF) generated from the BRDF for use in Monte-Carlo rendering.

Surface Termination of M1 Phase and Rational Design of Propane Ammoxidation Catalysts

Energy Technology Data Exchange (ETDEWEB)

Guliants, Vadim [Univ. of Cincinnati, OH (United States)

2015-02-16

This final report describes major accomplishments in this research project which has demonstrated that the M1 phase is the only crystalline phase required for propane ammoxidation to acrylonitrile and that a surface monolayer terminating the ab planes of the M1 phase is responsible for their activity and selectivity in this reaction. Fundamental studies of the topmost surface chemistry and mechanism of propane ammoxidation over the Mo-V-(Te,Sb)-(Nb,Ta)-O M1 and M2 phases resulted in the development of quantitative understanding of the surface molecular structure – reactivity relationships for this unique catalytic system. These oxides possess unique catalytic properties among mixed metal oxides, because they selectively catalyze three alkane transformation reactions, namely propane ammoxidation to acrylonitrile, propane oxidation to acrylic acid and ethane oxidative dehydrogenation, all of considerable economic significance. Therefore, the larger goal of this research was to expand this catalysis to other alkanes of commercial interest, and more broadly, demonstrate successful approaches to rational design of improved catalysts that can be applied to other selective (amm)oxidation processes.

Is It Rational to Assume that Infants Imitate Rationally? A Theoretical Analysis and Critique

Science.gov (United States)

Paulus, Markus

2012-01-01

It has been suggested that preverbal infants evaluate the efficiency of others' actions (by applying a "principle of rational action") and that they imitate others' actions rationally. The present contribution presents a conceptual analysis of the claim that preverbal infants imitate rationally. It shows that this ability rests on at least three…

Adapting Rational Unified Process (RUP) approach in designing a secure e-Tendering model

Science.gov (United States)

Mohd, Haslina; Robie, Muhammad Afdhal Muhammad; Baharom, Fauziah; Darus, Norida Muhd; Saip, Mohamed Ali; Yasin, Azman

2016-08-01

e-Tendering is an electronic processing of the tender document via internet and allow tenderer to publish, communicate, access, receive and submit all tender related information and documentation via internet. This study aims to design the e-Tendering system using Rational Unified Process approach. RUP provides a disciplined approach on how to assign tasks and responsibilities within the software development process. RUP has four phases that can assist researchers to adjust the requirements of various projects with different scope, problem and the size of projects. RUP is characterized as a use case driven, architecture centered, iterative and incremental process model. However the scope of this study only focusing on Inception and Elaboration phases as step to develop the model and perform only three of nine workflows (business modeling, requirements, analysis and design). RUP has a strong focus on documents and the activities in the inception and elaboration phases mainly concern the creation of diagrams and writing of textual descriptions. The UML notation and the software program, Star UML are used to support the design of e-Tendering. The e-Tendering design based on the RUP approach can contribute to e-Tendering developers and researchers in e-Tendering domain. In addition, this study also shows that the RUP is one of the best system development methodology that can be used as one of the research methodology in Software Engineering domain related to secured design of any observed application. This methodology has been tested in various studies in certain domains, such as in Simulation-based Decision Support, Security Requirement Engineering, Business Modeling and Secure System Requirement, and so forth. As a conclusion, these studies showed that the RUP one of a good research methodology that can be adapted in any Software Engineering (SE) research domain that required a few artifacts to be generated such as use case modeling, misuse case modeling, activity

Designing and Implementing the Intranet for ZhuHai State-Kai Polymer and New Materials Co.,Ltd

OpenAIRE

Chen, Si; Jiang, Min

2010-01-01

This Thesis was commissioned by Zhuhai State-Kai Polymer and New Materials company, which is a chemical and pharmacy SME in China. The Thesis aimed to design and implement the Intranet with the characteristics of the case company on the basis of the identified requirements. The designed Intranet innovates in a computerized system to replace the current manual system used in its business life. The questionnaire approach was used to gather the information and requirements both from the view...

Bounded Rationality and Budgeting

OpenAIRE

Ibrahim, Mukdad

2016-01-01

This article discusses the theory of bounded rationality which had been introduced by Herbert Simon in the 1950s. Simon introduced the notion of bounded rationality stating that while decision-makers strive for rationality, they are limited by the effect of the environment, their information process capacity and by the constraints on their information storage and retrieval capabilities. Moreover, this article tries to specifically blend this notion into budgeting, using the foundations of inc...

Biomimetics: From Bioinformatics to Rational Design of Dendrimers as Gene Carriers

Science.gov (United States)

Araya-Durán, Ingrid; Varas-Concha, Ignacio; Almonacid, Daniel Eduardo; González-Nilo, Fernando Danilo

2015-01-01

Biomimetics, or the use of principles of Nature for developing new materials, is a paradigm that could help Nanomedicine tremendously. One of the current challenges in Nanomedicine is the rational design of new efficient and safer gene carriers. Poly(amidoamine) (PAMAM) dendrimers are a well-known class of nanoparticles, extensively used as non-viral nucleic acid carriers, due to their positively charged end-groups. Yet, there are still several aspects that can be improved for their successful application in in vitro and in vivo systems, including their affinity for nucleic acids as well as lowering their cytotoxicity. In the search of new functional groups that could be used as new dendrimer-reactive groups, we followed a biomimetic approach to determine the amino acids with highest prevalence in protein-DNA interactions. Then we introduced them individually as terminal groups of dendrimers, generating a new class of nanoparticles. Molecular dynamics studies of two systems: PAMAM-Arg and PAMAM-Lys were also performed in order to describe the formation of complexes with DNA. Results confirmed that the introduction of amino acids as terminal groups in a dendrimer increases their affinity for DNA and the interactions in the complexes were characterized at atomic level. We end up by briefly discussing additional modifications that can be made to PAMAM dendrimers to turned them into promising new gene carriers. PMID:26382062

Random polyfluorene co-polymers designed for a better optical absorption coverage of the visible region of the electromagnetic spectrum

Directory of Open Access Journals (Sweden)

D. A. Gedefaw

2014-01-01

Full Text Available Two alternating polyfluorenes (APFO15-F8BT and APFO3-F8BT with full absorption of the visible region of the electromagnetic radiation were designed and synthesized for bulk-heterojunction solar cell devices. The optical and electrochemical properties of the two polymers were studied. The two polymers exhibited strong absorption in the visible region with no significant valley over the visible region extending up to 650 nm. Deep HOMO and ideally situated LUMO energy levels were the characteristics of the two polymers as revealed from the square wave voltammogram study: desired properties for extracting high open circuit voltage and for a facile charge transfer to the acceptor component in devices to take place, respectively. Photovoltaic devices were fabricated by blending the two polymers with PCBM[70] and up to ~2% power conversion efficiency were obtained. DOI: http://dx.doi.org/10.4314/bcse.v28i1.14

Rational valuations

Directory of Open Access Journals (Sweden)

Georg Spielthenner

2007-01-01

Full Text Available Valuations are ubiquitous. We may be for or against genetically modified food; we find some politicians irresponsible; we prefer Beethoven to rock ‘n’ roll or vice versa; some enjoy bird-watching while others find it boring; and we may think that we have to tighten up on green-house gas emissions. Valuing is pervasive and often we are not even aware that we are valuing. However, many of ourvaluations are ill grounded and rationally defective. They are frequently based on misinformation, sloppy thinking, prejudice, and are biased in many ways as psychological research shows. For this reason there is widespread agreement among phi-losophers that we need an account of substantive valuational rationality, both for the theory of practical reasoning and for ethics as well. My main objectin this paper is to outline such an account and to present a principle that allows a non-technical rational criticism of valuations

Rational emotions.

Science.gov (United States)

Meshulam, Meir; Winter, Eyal; Ben-Shakhar, Gershon; Aharon, Itzhak

2012-01-01

We present here the concept of rational emotions: Emotions may be directly controlled and utilized in a conscious, analytic fashion, enabling an individual to size up a situation, to determine that a certain "mental state" is strategically advantageous and adjust accordingly. Building on the growing body of literature recognizing the vital role of emotions in determining decisions, we explore the complementary role of rational choice in choosing emotional states. Participants played the role of "recipient" in the dictator game, in which an anonymous "dictator" decides how to split an amount of money between himself and the recipient. A subset of recipients was given a monetary incentive to be angry at low-split offers. That subset demonstrated increased physiological arousal at low offers relative to high offers as well as more anger than other participants. These results provide a fresh outlook on human decision-making and contribute to the continuing effort to build more complete models of rational behavior.

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications.

Science.gov (United States)

Viswanathan, Vinila N; Rao, Arun D; Pandey, Upendra K; Kesavan, Arul Varman; Ramamurthy, Praveen C

2017-01-01

A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1 , exhibited a highest occupied molecular orbital (HOMO) energy level at -5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2 , were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices. Moreover, a decrease in the torsion angle between the units was also observed for the fluorinated polymer P2 due to the enhanced electrostatic interaction between the fluorine substituents and sulfur atoms, leading to a high hole mobility. The use of a fused π-bridge in polymer P3 for the enhancement of the planarity as compared to the P1 backbone was also studied. This enhanced planarity led to the highest observed mobility among the reported three polymers as well as to an improvement in the device efficiency by more than 40% for P3 .

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

Science.gov (United States)

Viswanathan, Vinila N; Rao, Arun D; Pandey, Upendra K; Kesavan, Arul Varman

2017-01-01

A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1, exhibited a highest occupied molecular orbital (HOMO) energy level at −5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2, were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices. Moreover, a decrease in the torsion angle between the units was also observed for the fluorinated polymer P2 due to the enhanced electrostatic interaction between the fluorine substituents and sulfur atoms, leading to a high hole mobility. The use of a fused π-bridge in polymer P3 for the enhancement of the planarity as compared to the P1 backbone was also studied. This enhanced planarity led to the highest observed mobility among the reported three polymers as well as to an improvement in the device efficiency by more than 40% for P3. PMID:28546844

Models for Rational Number Bases

Science.gov (United States)

Pedersen, Jean J.; Armbruster, Frank O.

1975-01-01

This article extends number bases to negative integers, then to positive rationals and finally to negative rationals. Methods and rules for operations in positive and negative rational bases greater than one or less than negative one are summarized in tables. Sample problems are explained and illustrated. (KM)

Rational Design of Disulfide Bonds Increases Thermostability of a Mesophilic 1,3-1,4-β-Glucanase from Bacillus terquilensis.

Directory of Open Access Journals (Sweden)

Chengtuo Niu

Full Text Available 1,3-1,4-β-glucanase is an important biocatalyst in brewing industry and animal feed industry, while its low thermostability often reduces its application performance. In this study, the thermostability of a mesophilic β-glucanase from Bacillus terquilensis was enhanced by rational design and engineering of disulfide bonds in the protein structure. Protein spatial configuration was analyzed to pre-exclude the residues pairs which negatively conflicted with the protein structure and ensure the contact of catalytic center. The changes in protein overall and local flexibility among the wild-type enzyme and the designated mutants were predicted to select the potential disulfide bonds for enhancement of thermostability. Two residue pairs (N31C-T187C and P102C-N125C were chosen as engineering targets and both of them were proved to significantly enhance the protein thermostability. After combinational mutagenesis, the double mutant N31C-T187C/P102C-N125C showed a 48.3% increase in half-life value at 60°C and a 4.1°C rise in melting temperature (Tm compared to wild-type enzyme. The catalytic property of N31C-T187C/P102C-N125C mutant was similar to that of wild-type enzyme. Interestingly, the optimal pH of double mutant was shifted from pH6.5 to pH6.0, which could also increase its industrial application. By comparison with mutants with single-Cys substitutions, the introduction of disulfide bonds and the induced new hydrogen bonds were proved to result in both local and overall rigidification and should be responsible for the improved thermostability. Therefore, the introduction of disulfide bonds for thermostability improvement could be rationally and highly-effectively designed by combination with spatial configuration analysis and molecular dynamics simulation.

Rheology of Supramolecular Polymers

DEFF Research Database (Denmark)

Shabbir, Aamir

Supramolecular polymers are a broad class of materials that include all polymerscapable of associating via secondary interactions. These materials represent an emerging class of systems with superior versatility compared to classical polymers with applications in food stuff, coatings, cost...... efficient processes or biomedical areas. Design and development of supramolecular polymers using ionic, hydrogen bonding or transition metal complexes with tailored properties requires deep understanding of dynamics both in linear and non-linear deformations. While linear rheology is important to understand...... the dynamics under equilibrium conditions, extensional rheology is relevant during the processing or in the usage of polymers utilizing supramolecular associations for example, acrylic based pressure sensitive adhesives are subjected to extensional deformations during the peeling where strain hardening...

Polymers for Protein Conjugation

Directory of Open Access Journals (Sweden)

Gianfranco Pasut

2014-01-01

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

Rational design of modular circuits for gene transcription: A test of the bottom-up approach

Directory of Open Access Journals (Sweden)

Giordano Emanuele

2010-11-01

Full Text Available Abstract Background Most of synthetic circuits developed so far have been designed by an ad hoc approach, using a small number of components (i.e. LacI, TetR and a trial and error strategy. We are at the point where an increasing number of modular, inter-changeable and well-characterized components is needed to expand the construction of synthetic devices and to allow a rational approach to the design. Results We used interchangeable modular biological parts to create a set of novel synthetic devices for controlling gene transcription, and we developed a mathematical model of the modular circuits. Model parameters were identified by experimental measurements from a subset of modular combinations. The model revealed an unexpected feature of the lactose repressor system, i.e. a residual binding affinity for the operator site by induced lactose repressor molecules. Once this residual affinity was taken into account, the model properly reproduced the experimental data from the training set. The parameters identified in the training set allowed the prediction of the behavior of networks not included in the identification procedure. Conclusions This study provides new quantitative evidences that the use of independent and well-characterized biological parts and mathematical modeling, what is called a bottom-up approach to the construction of gene networks, can allow the design of new and different devices re-using the same modular parts.

Are security analysts rational? a literature review

OpenAIRE

Peixinho, Rúben; Coelho, Luís; Taffler, Richard J.

2005-01-01

Rational choice theory and bounded rationality constitute the basis for the discussion in several areas regarding human rationality. In finance, this discussion has been made between traditional finance and behavioural finance approach, which have different perspectives concerning market agents’ rationality. This paper reviews several studies addressing rationality among security analysts. The analysis shows that analysts’systematic optimism seems to be inconsistent with rationality....

Recent Advances in Wide-Bandgap Photovoltaic Polymers.

Science.gov (United States)

Cai, Yunhao; Huo, Lijun; Sun, Yanming

2017-06-01

The past decade has witnessed significant advances in the field of organic solar cells (OSCs). Ongoing improvements in the power conversion efficiency of OSCs have been achieved, which were mainly attributed to the design and synthesis of novel conjugated polymers with different architectures and functional moieties. Among various conjugated polymers, the development of wide-bandgap (WBG) polymers has received less attention than that of low-bandgap and medium-bandgap polymers. Here, we briefly summarize recent advances in WBG polymers and their applications in organic photovoltaic (PV) devices, such as tandem, ternary, and non-fullerene solar cells. Addtionally, we also dissuss the application of high open-circuit voltage tandem solar cells in PV-driven electrochemical water dissociation. We mainly focus on the molecular design strategies, the structure-property correlations, and the photovoltaic performance of these WBG polymers. Finally, we extract empirical regularities and provide invigorating perspectives on the future development of WBG photovoltaic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Designing N-halamine based antibacterial surface on polymers: Fabrication, characterization, and biocidal functions

Energy Technology Data Exchange (ETDEWEB)

Chen Yong, E-mail: ychen168@126.com [Department of Applied Chemistry, College of Chemical and Environmental Engineering, Shandong University of Science and Technology, 579 Qianwangang Rd., Huangdao Zone, Qingdao 266510 (China); Han Qiuxia [Department of Biological Engineering, College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China)

2011-05-01

We demonstrate a valuable method to generate reactive groups on inert polymer surfaces and bond antibacterial agents for biocidal ability. Polystyrene (PS) surfaces were functionalized by spin coating of sub-monolayer and monolayer films of poly(styrene-b-tert-butyl acrylate) (PS-PtBA) block copolymer from solutions in toluene. PS-PtBA self-assembled to a bilayer structure on PS that contains a surface layer of the PtBA blocks ordering at the air-polymer interface and a bottom layer of the PS blocks entangling with the PS substrate. The thickness of PtBA layer could be linearly controlled by the concentration of the spin coating solution and a 2.5 nm saturated monolayer coverage of PtBA was achieved at 0.35% (w/w). Carboxyl groups were generated by exposing the tert-butyl ester groups of PtBA on saturated surface to trifluoroacetic acid (TFA) to bond tert-butylamine via amide bonds that were further chlorinated to N-halamine with NaOCl solution. The density of N-halamine on the chlorinated surface was calculated to be 1.05 x 10{sup -5} mol/m{sup 2} by iodimetric/thiosulfate titration. Presented data showed the N-halamine surface provided powerful antibacterial activities against Staphylococcus aureus and Escherichia coli. Over 50% of the chlorine lost after UVA irradiation could be regained upon rechlorination. This design concept can be virtually applied to any inert polymer by choosing appropriate block copolymers and antibacterial agents to attain desirable biocidal activity.

Future product design

DEFF Research Database (Denmark)

Andreasen, Mogens Myrup

1997-01-01

This paper (in form of overheads) formulate new challenges and possibilities for engineering design, utilizing rationalization effect from modularisation, re-use and transparaency.......This paper (in form of overheads) formulate new challenges and possibilities for engineering design, utilizing rationalization effect from modularisation, re-use and transparaency....

International PolyScene-workshop on polymer electronics. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-07-01

Topics of this proceedings are: RFID: tagging the opportunities and threats for polymer electronics; polymeric semiconductor development for thin film transistors; hole and electron transport in semiconducting polymers for organic electronics; a circuit based strategy for the development of polymer TFTS; towards a technology for all-polymer electronics; electrically doped organic semiconductors: physics and device applications; organic solar cells and photodetectors; organic solar cells: trends, challenges and positioning in the field of thin-film solar cell technologies; technical production of plastic solar cells: an overview; optical and ESR studies on polymer/fullerene composites for solar cells; targets for OTFT development for active matrix displays; reflective electroactive display (READ) technology and opportunities in printed devices; OFETs, OLEDs, OLDs: organic devices for future polytronic systems; design of active polymer materials and their application in electronic devices; blue emitting ALQ3 for full color organic displays; technologies for the reel-to-reel production of flexible polytronic systems; new developments in polyester films for flexible electronics; printed conductive polymer structures; non-lithographic patterning of polymer transistors; laser structuring- a method for polymer and metal patterning; direct printing of polymer transistor circuits; molecular design of interphases - the key for the development of reliable polymer based products; wafer level packaging - encapsulation of micro structures.

Rationally reduced libraries for combinatorial pathway optimization minimizing experimental effort.

Science.gov (United States)

Jeschek, Markus; Gerngross, Daniel; Panke, Sven

2016-03-31

Rational flux design in metabolic engineering approaches remains difficult since important pathway information is frequently not available. Therefore empirical methods are applied that randomly change absolute and relative pathway enzyme levels and subsequently screen for variants with improved performance. However, screening is often limited on the analytical side, generating a strong incentive to construct small but smart libraries. Here we introduce RedLibs (Reduced Libraries), an algorithm that allows for the rational design of smart combinatorial libraries for pathway optimization thereby minimizing the use of experimental resources. We demonstrate the utility of RedLibs for the design of ribosome-binding site libraries by in silico and in vivo screening with fluorescent proteins and perform a simple two-step optimization of the product selectivity in the branched multistep pathway for violacein biosynthesis, indicating a general applicability for the algorithm and the proposed heuristics. We expect that RedLibs will substantially simplify the refactoring of synthetic metabolic pathways.

``Smart'' Surfaces of Polymer Brushes

Science.gov (United States)

Wang, Qiang; Meng, Dong

2009-03-01

``Smart'' surfaces, also known as stimuli-responsive surfaces, can change their properties (e.g., wettability, adhesion, friction, elasticity, and biocompatibility) in response to external stimuli (e.g., temperature, pressure, light, solvent selectivity, ionic strength, type of salt, pH, applied electric field, etc.). In this work, we use numerical self-consistent field calculations to study in detail the structure and stimuli- responses of various polymer brushes, including (1) the thermo- response of PNIPAM brushes in water, (2) solvent-response of uncharged diblock copolymer brushes, and (3) the stimuli- response of charged two-component polymer brushes (including both the binary A/B brushes and diblock copolymer A-B brushes) to ionic strength, pH, and applied electric field. Among the many design parameters (e.g., chain lengths, grafting densities, A-B incompatibility, degree of ionization of charged polymers, etc.) we identify those that strongly affect the surface switchability. Such knowledge is useful to the experimental design of these smart polymer brushes for their applications.

Empirical evidence for resource-rational anchoring and adjustment.

Science.gov (United States)

Lieder, Falk; Griffiths, Thomas L; M Huys, Quentin J; Goodman, Noah D

2018-04-01

People's estimates of numerical quantities are systematically biased towards their initial guess. This anchoring bias is usually interpreted as sign of human irrationality, but it has recently been suggested that the anchoring bias instead results from people's rational use of their finite time and limited cognitive resources. If this were true, then adjustment should decrease with the relative cost of time. To test this hypothesis, we designed a new numerical estimation paradigm that controls people's knowledge and varies the cost of time and error independently while allowing people to invest as much or as little time and effort into refining their estimate as they wish. Two experiments confirmed the prediction that adjustment decreases with time cost but increases with error cost regardless of whether the anchor was self-generated or provided. These results support the hypothesis that people rationally adapt their number of adjustments to achieve a near-optimal speed-accuracy tradeoff. This suggests that the anchoring bias might be a signature of the rational use of finite time and limited cognitive resources rather than a sign of human irrationality.

Limited rationality and strategic interaction

DEFF Research Database (Denmark)

Fehr, Ernst; Tyran, Jean-Robert

2008-01-01

Much evidence suggests that people are heterogeneous with regard to their abilities to make rational, forward-looking decisions. This raises the question as to when the rational types are decisive for aggregate outcomes and when the boundedly rational types shape aggregate results. We examine...... this question in the context of a long-standing and important economic problem: the adjustment of nominal prices after an anticipated monetary shock. Our experiments suggest that two types of bounded rationality-money illusion and anchoring-are important behavioral forces behind nominal inertia. However......, depending on the strategic environment, bounded rationality has vastly different effects on aggregate price adjustment. If agents' actions are strategic substitutes, adjustment to the new equilibrium is extremely quick, whereas under strategic complementarity, adjustment is both very slow and associated...

Control of Polymer Glass Formation Behaviour Using Molecular Diluents and Dynamic Interfaces

Science.gov (United States)

Mangalara, Jayachandra Hari

The end use application of polymeric materials is mainly determined by their viscosity, thermal stability and processability. These properties are primarily determined by the segmental relaxation time (taualpha) of the polymer and its glass state modulus, which determines its glassy mechanical response. Developing design principles to obtain rational control over these properties would enable fabrication of new polymers or polymer blends with improved thermal stability, enhanced processability and better mechanical robustness of the material. Introduction of diluents and nanostructuring of the material serve as invaluable tools for altering polymers' glass transition and associated dynamic and mechanical properties. Besides providing guidelines for technologically important improvements in processability, glassy mechanical properties, and transport behavior, diluent effects and behavior of nanostructured materials can provide insights into the fundamental physics of the glass transition, for example, by elucidating the interrelation between high- and low-frequency structural relaxation processes. It has been previously suggested that there exists a similarity between how diluents and interfaces impact the glass formation behavior of the polymer, raising the possibility that the effects of these two polymer modifications may be separate manifestations of a common set of physics in glass forming polymers. Here we address several interrelated questions in the understanding of glass formation in polymer/diluent blends and nanostructured polymers. First, what is the relationship between a diluent's molecular structure and its impact on a polymer's glass formation behavior? How does this compare to the effect of interfaces? Second, how does the introduction of diluents impact the role of interfaces in modifying polymer glass formation? Third, how does the introduction of interfaces impact metrology of the polymer glass transition? Finally, we address a major open

Interpolation of rational matrix functions

CERN Document Server

Ball, Joseph A; Rodman, Leiba

1990-01-01

This book aims to present the theory of interpolation for rational matrix functions as a recently matured independent mathematical subject with its own problems, methods and applications. The authors decided to start working on this book during the regional CBMS conference in Lincoln, Nebraska organized by F. Gilfeather and D. Larson. The principal lecturer, J. William Helton, presented ten lectures on operator and systems theory and the interplay between them. The conference was very stimulating and helped us to decide that the time was ripe for a book on interpolation for matrix valued functions (both rational and non-rational). When the work started and the first partial draft of the book was ready it became clear that the topic is vast and that the rational case by itself with its applications is already enough material for an interesting book. In the process of writing the book, methods for the rational case were developed and refined. As a result we are now able to present the rational case as an indepe...

Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters.

Science.gov (United States)

Li, Shu; Tian, Yiwei; Jones, David S; Andrews, Gavin P

2016-02-01

The aim of this article was to construct a T-ϕ phase diagram for a model drug (FD) and amorphous polymer (Eudragit® EPO) and to use this information to understand the impact of how temperature-composition coordinates influenced the final properties of the extrudate. Defining process boundaries and understanding drug solubility in polymeric carriers is of utmost importance and will help in the successful manufacture of new delivery platforms for BCS class II drugs. Physically mixed felodipine (FD)-Eudragit(®) EPO (EPO) binary mixtures with pre-determined weight fractions were analysed using DSC to measure the endset of melting and glass transition temperature. Extrudates of 10 wt% FD-EPO were processed using temperatures (110°C, 126°C, 140°C and 150°C) selected from the temperature-composition (T-ϕ) phase diagrams and processing screw speed of 20, 100 and 200rpm. Extrudates were characterised using powder X-ray diffraction (PXRD), optical, polarised light and Raman microscopy. To ensure formation of a binary amorphous drug dispersion (ADD) at a specific composition, HME processing temperatures should at least be equal to, or exceed, the corresponding temperature value on the liquid-solid curve in a F-H T-ϕ phase diagram. If extruded between the spinodal and liquid-solid curve, the lack of thermodynamic forces to attain complete drug amorphisation may be compensated for through the use of an increased screw speed. Constructing F-H T-ϕ phase diagrams are valuable not only in the understanding drug-polymer miscibility behaviour but also in rationalising the selection of important processing parameters for HME to ensure miscibility of drug and polymer.

The Design of Polymer Planar Optical Triplexer with MMI Filter and Directional Coupler

Directory of Open Access Journals (Sweden)

V. Jerabek

2013-12-01

Full Text Available Optical bidirectional WDM transceiver is a key component of the Passive Optical Network of the Fiber to the Home topology. Essential parts of such transceivers are filters that combine multiplexing and demultiplexing function of optical signal (triplexing filters. In this paper we report about a design of a new planar optical multi-wavelength selective system triplexing filter, which combines a multimode interference filter with directional coupler based on the epoxy polymer SU-8 on Si/SiO2 substrate. The optical triplexing filter was designed using the Beam Propagation Method. The aim of this project was to optimize the triplexing filter optical parameters and to minimize the planar optical wavelength selective system dimensions. The multimode interference filter was used for separation of downstream optical signal in designed optoelectronic integrated WDM transceiver. The directional coupler was used for adding of upstream optical signal.

Rational design of anatase TiO2 architecture with hierarchical nanotubes and hollow microspheres for high-performance dye-sensitized solar cells

Science.gov (United States)

Gu, Jiuwang; Khan, Javid; Chai, Zhisheng; Yuan, Yufei; Yu, Xiang; Liu, Pengyi; Wu, Mingmei; Mai, Wenjie

2016-01-01

Large surface area, sufficient light-harvesting and superior electron transport property are the major factors for an ideal photoanode of dye-sensitized solar cells (DSSCs), which requires rational design of the nanoarchitectures and smart integration of state-of-the-art technologies. In this work, a 3D anatase TiO2 architecture consisting of vertically aligned 1D hierarchical TiO2 nanotubes (NTs) with ultra-dense branches (HTNTs, bottom layer) and 0D hollow TiO2 microspheres with rough surface (HTS, top layer) is first successfully constructed on transparent conductive fluorine-doped tin oxide glass through a series of facile processes. When used as photoanodes, the DSSCs achieve a very large short-current density of 19.46 mA cm-2 and a high overall power conversion efficiency of 8.38%. The remarkable photovoltaic performance is predominantly ascribed to the enhanced charge transport capacity of the NTs (function as the electron highway), the large surface area of the branches (act as the electron branch lines), the pronounced light harvesting efficiency of the HTS (serve as the light scattering centers), and the engineered intimate interfaces between all of them (minimize the recombination effect). Our work demonstrates a possibility of fabricating superior photoanodes for high-performance DSSCs by rational design of nanoarchitectures and smart integration of multi-functional components.

Decision-Making: Are Plants More Rational than Animals?

Science.gov (United States)

Schmid, Bernhard

2016-07-25

A new study presents a novel experimental design and allows a test of risk sensitivity in plants. Faced with a choice between constant and variable resource supply, they make a rational decision for the option that maximizes fitness, a fact rarely observed in animals. Copyright © 2016 Elsevier Ltd. All rights reserved.

History of Economic Rationalities

DEFF Research Database (Denmark)

This book concentrates upon how economic rationalities have been embedded into particular historical practices, cultures, and moral systems. Through multiple case-studies, situated in different historical contexts of the modern West, the book shows that the development of economic rationalities...... takes place in the meeting with other regimes of thought, values, and moral discourses. The book offers new and refreshing insights, ranging from the development of early economic thinking to economic aspects and concepts in the works of classical thinkers such as Thomas Hobbes, John Locke and Karl Marx......, to the role of economic reasoning in contemporary policies of art and health care. With economic rationalities as the read thread, the reader is offered a unique chance of historical self-awareness and recollection of how economic rationality became the powerful ideological and moral force that it is today....

Effects of forage ensiling and ration fermentation on total mixed ration pH, ruminal fermentation and performance of growing Holstein-Zebu cross steers.

Science.gov (United States)

Meenongyai, Watcharawit; Pattarajinda, Virote; Stelzleni, Alexander M; Sethakul, Jutarat; Duangjinda, Monchai

2017-09-01

Our objective was to determine the effect of forage ensiling and ration fermentation on total mixed ration pH, ruminal fermentation and animal performance. Thirty Holstein-Zebu cross steers were allotted to feeding treatments for 188 days in a randomized complete block design including: fresh grass-total mixed ration (GTMR; pH 4.7), grass silage-TMR (STMR; pH 4.0) and fermented-TMR (FTMR; pH 3.5). Average daily gain for STMR was greatest during the first 3 months period; however, that for FTMR tended to be greater than GTMR during the second 3 months period (P ruminal NH 3 -N content than STMR. Total volatile fatty acids post-feeding was greatest for GTMR (P Ruminal proportions of acetic and butyric acids were greater for FTMR than GTMR (P ruminal pH. STMR and FTMRs can be used to maintain performance of growing crossbred Holstein steers. © 2017 Japanese Society of Animal Science.

Polymer Basics: Classroom Activities Manipulating Paper Clips to Introduce the Structures and Properties of Polymers

Science.gov (United States)

Umar, Yunusa

2014-01-01

A simple and effective hands-on classroom activity designed to illustrate basic polymer concepts is presented. In this activity, students build primary structures of homopolymers and different arrangements of monomers in copolymer using paper clips as monomers. The activity supports formation of a basic understanding of polymer structures,…

Synthesis of Acenaphthyl and Phenanthrene Based Fused-Aromatic Thienopyrazine Co-Polymers for Photovoltaic and Thin Film Transistor Applications

KAUST Repository

Mondal, Rajib

2009-08-11

Dithiophene and fluorene co-polymers containing fused aromatic thieno[3,4-b]pyrazine moieties were synthesized for organic thin film transistor (OTFT) and organic photovoltaic (OPV) applications. Suzuki and Stille polycondensation reactions were used for the polymerization. The band gap (Eg) of the polymers was tuned in the range of 1.15-1.6 eV to match the solar spectrum. Density functional theory calculations were carried out to rationalize the low band gaps. These polymers showed field effect mobility (μ) as high as 0.2 cm2/(V.s) with an on/off ratio as high as 106 in OTFT devices. Interestingly, one polymer in this class also showed ambipolar charge transport. Power conversion efficiency (PCE) up to 1.3% was achieved in bulk heterojunction solar cells, indicating that these materials are promising for OPV applications. © 2009 American Chemical Society.

Solution-processed parallel tandem polymer solar cells using silver nanowires as intermediate electrode.

Science.gov (United States)

Guo, Fei; Kubis, Peter; Li, Ning; Przybilla, Thomas; Matt, Gebhard; Stubhan, Tobias; Ameri, Tayebeh; Butz, Benjamin; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2014-12-23

Tandem architecture is the most relevant concept to overcome the efficiency limit of single-junction photovoltaic solar cells. Series-connected tandem polymer solar cells (PSCs) have advanced rapidly during the past decade. In contrast, the development of parallel-connected tandem cells is lagging far behind due to the big challenge in establishing an efficient interlayer with high transparency and high in-plane conductivity. Here, we report all-solution fabrication of parallel tandem PSCs using silver nanowires as intermediate charge collecting electrode. Through a rational interface design, a robust interlayer is established, enabling the efficient extraction and transport of electrons from subcells. The resulting parallel tandem cells exhibit high fill factors of ∼60% and enhanced current densities which are identical to the sum of the current densities of the subcells. These results suggest that solution-processed parallel tandem configuration provides an alternative avenue toward high performance photovoltaic devices.

Polymer-Polymer Förster Resonance Energy Transfer Significantly Boosts the Power Conversion Efficiency of Bulk-Heterojunction Solar Cells.

Science.gov (United States)

Gupta, Vinay; Bharti, Vishal; Kumar, Mahesh; Chand, Suresh; Heeger, Alan J

2015-08-01

Optically resonant donor polymers can exploit a wider range of the solar spectrum effectively without a complicated tandem design in an organic solar cell. Ultrafast Förster resonance energy transfer (FRET) in a polymer-polymer system that significantly improves the power conversion efficiency in bulk heterojunction polymer solar cells from 6.8% to 8.9% is demonstrated, thus paving the way to achieving 15% efficient solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Psychology and the Rationality of Emotion.

Science.gov (United States)

Clore, Gerald L

2011-04-01

Questions addressed by recent psychological research on emotion include questions about how thought shapes emotion and how emotion, in turn, shapes thought. Research on emotion and cognition paints a somewhat different picture than that seen in traditional discussions of passion and reason. This article reviews several aspects of this research, concentrating specifically on three views of rationality: Rationality as Process, Rationality as Product, and Rationality as Outcome.

Psychology and the Rationality of Emotion*

OpenAIRE

Clore, Gerald L.

2011-01-01

Questions addressed by recent psychological research on emotion include questions about how thought shapes emotion and how emotion, in turn, shapes thought. Research on emotion and cognition paints a somewhat different picture than that seen in traditional discussions of passion and reason. This article reviews several aspects of this research, concentrating specifically on three views of rationality: Rationality as Process, Rationality as Product, and Rationality as Outcome.

Optimization of cardiovascular stent against restenosis: factorial design-based statistical analysis of polymer coating conditions.

Directory of Open Access Journals (Sweden)

Gayathri Acharya

Full Text Available The objective of this study was to optimize the physicodynamic conditions of polymeric system as a coating substrate for drug eluting stents against restenosis. As Nitric Oxide (NO has multifunctional activities, such as regulating blood flow and pressure, and influencing thrombus formation, a continuous and spatiotemporal delivery of NO loaded in the polymer based nanoparticles could be a viable option to reduce and prevent restenosis. To identify the most suitable carrier for S-Nitrosoglutathione (GSNO, a NO prodrug, stents were coated with various polymers, such as poly (lactic-co-glycolic acid (PLGA, polyethylene glycol (PEG and polycaprolactone (PCL, using solvent evaporation technique. Full factorial design was used to evaluate the effects of the formulation variables in polymer-based stent coatings on the GSNO release rate and weight loss rate. The least square regression model was used for data analysis in the optimization process. The polymer-coated stents were further assessed with Differential scanning calorimetry (DSC, Fourier transform infrared spectroscopy analysis (FTIR, Scanning electron microscopy (SEM images and platelet adhesion studies. Stents coated with PCL matrix displayed more sustained and controlled drug release profiles than those coated with PLGA and PEG. Stents coated with PCL matrix showed the least platelet adhesion rate. Subsequently, stents coated with PCL matrix were subjected to the further optimization processes for improvement of surface morphology and enhancement of the drug release duration. The results of this study demonstrated that PCL matrix containing GSNO is a promising system for stent surface coating against restenosis.

Design thinking between rationalism and romanticism

DEFF Research Database (Denmark)

Engholm, Ida; Goldschmidt Salamon, Karen-Lisa

2017-01-01

This article presents a longue durée history of modern design thought, with particular focus on recurrent ideological frictions. Drawing on design history, design anthropology and cultural studies, the authors present an overview of more than 200 years of developments in European and North Americ...

Study of equivalent retention among different polymer-solvent systems in thermal field-flow fractionation

International Nuclear Information System (INIS)

Kim, Won Suk; Park, Young Hun; Lee, Dai Woon; Moon, Myeong Hee; Yu, Euy Kyung

1998-01-01

An equivalent retention has been experimentally observed in thermal field-flow fractionation (ThFF) for different polymer-solvent systems. It is shown that iso-retention between two sets of polymer-solvent systems can be obtained by adjusting the temperature difference (ΔT) according to the difference in the ration of ordinary diffusion coefficient to thermal diffusion coefficient. This method uses a compensation of field strength (ΔT) in ThFFF at a fixed condition of cold wall temperature. It is applied for the calculation of molecular weight of polymers based on a calibration run of different standards obtained at an adjusted ΔT. The polymer standards used in this study are polystyrene (PS), polymethylmethacrylate (PMMA), and polytetrahydrofuran (PTHF). Three carrier solvents, tetrahydrofuran (THF), methylethylketone (MEK) and ethylacetate (ETAc) were employed. Though the accuracy in the calculation of molecular weight is dependent on the difference in the slope of log λ vs. log M which is related to Mark-Houwink constant a, it shows reasonable agreement within about 6% of relative error in molecular weight calculation for the polymer-solvent systems having similar a value

Moral Credentialing and the Rationalization of Misconduct

Science.gov (United States)

Brown, Ryan P.; Tamborski, Michael; Wang, Xiaoqian; Barnes, Collin D.; Mumford, Michael D.; Connelly, Shane; Devenport, Lynn D.

2010-01-01

Recent studies lead to the paradoxical conclusion that the act of affirming one’s egalitarian or pro-social values and virtues might subsequently facilitate prejudiced or self-serving behavior, an effect previously referred to as “moral credentialing.” The present study extends this paradox to the domain of academic misconduct and investigates the hypothesis that such an effect might be limited by the extent to which misbehavior is rationalizable. Using a paradigm designed to investigate deliberative and rationalized forms of cheating (von Hippel, Lakin, & Shakarchi, 2005), we found that when participants had credentialed themselves (versus a non-close acquaintance) via a set of hypothetical moral dilemmas, they were more likely to cheat on a subsequent math task, but only if cheating was highly rationalizable. When cheating was difficult to rationalize, moral credentialing had almost no impact on cheating. PMID:21503267

Diketopyrrolopyrrole polymers for organic solar cells

NARCIS (Netherlands)

Li, Wei Wei; Hendriks, K.H.; Wienk, M.M.; Janssen, R.A.J.

2016-01-01

Conspectus Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a

Engineering of budesonide-loaded lipid-polymer hybrid nanoparticles using a quality-by-design approach.

Science.gov (United States)

Leng, Donglei; Thanki, Kaushik; Fattal, Elias; Foged, Camilla; Yang, Mingshi

2017-08-25

Chronic obstructive pulmonary disease (COPD) is a complex disease, characterized by persistent airflow limitation and chronic inflammation. The purpose of this study was to design lipid-polymer hybrid nanoparticles (LPNs) loaded with the corticosteroid, budesonide, which could potentially be combined with small interfering RNA (siRNA) for COPD management. Here, we prepared LPNs based on the biodegradable polymer poly(dl-lactic-co-glycolic acid) (PLGA) and the cationic lipid dioleyltrimethylammonium propane (DOTAP) using a double emulsion solvent evaporation method. A quality-by-design (QbD) approach was adopted to define the optimal formulation parameters. The quality target product profile (QTPP) of the LPNs was identified based on risk assessment. Two critical formulation parameters (CFPs) were identified, including the theoretical budesonide loading and the theoretical DOTAP loading. The CFPs were linked to critical quality attributes (CQAs), which included the intensity-based hydrodynamic particle diameter (z-average), the polydispersity index (PDI), the zeta-potential, the budesonide encapsulation efficiency, the actual budesonide loading and the DOTAP encapsulation efficiency. A response surface methodology (RSM) was applied for the experimental design to evaluate the influence of the CFPs on the CQAs, and to identify the optimal operation space (OOS). All nanoparticle dispersions displayed monodisperse size distributions (PDIPLGA increases when increasing the initial amount of budesonide. The OOS was modeled by applying the QTPP. The OOS had a budesonide encapsulation efficiency higher than 30%, a budesonide loading above 15μg budesonide/mg PLGA, a zeta-potential higher than 35mV and a DOTAP encapsulation efficiency above 50%. This study shows the importance of systematic formulation design for understanding the effect of formulation parameters on the characteristics of LPNs, eventually resulting in the identification of an OOS. Copyright © 2017 Elsevier B

Testing bounded rationality against full rationality in job changing behavior

OpenAIRE

Contini, Bruno; Morini, Matteo

2007-01-01

In this paper we question the hypothesis of full rationality in the context of job changing behaviour, via simple econometric explorations on microdata drawn from WHIP (Worker Histories Italian Panel). Workers' performance is compared at the end of a three-year time window that starts when choices are expressed, under the accepted notion that the main driving forces of job change are future real wages and expected job quality. Bounded rationality suggests that individuals will search for new ...

Testing Bounded Rationality Against Full Rationality in Job Changing Behavior

OpenAIRE

Bruno Contini

2008-01-01

In this paper I question the hypothesis of full rationality in the context of job changing behaviour, via simple econometric explorations on microdata drawn from WHIP (Worker Histories Italian Panel). Workers’ performance is compared at the end of a three-year time window that starts when choices are expressed, under the accepted notion that the main driving forces of job change are future real wages and expected job quality. Bounded rationality suggests that individuals will search for new o...

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery Seuil de dégradation mécanique de solutions de polymères utilisés en récupération assistée des hydrocarbures

Directory of Open Access Journals (Sweden)

Dupas A.

2013-02-01

Full Text Available Water soluble polymers such as polyacrylamide are used in polymer flooding, which is an advanced technique of Enhanced Oil Recovery (EOR. It aims at improving crude oil displacement in reservoir by pushing it with a viscous injected fluid. Polymer flood is challenged by mechanical degradation of long macromolecules during intense flows. Many studies reported that above a critical extensional rate hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · , polymer chains can break and lose their rheological properties. The molecular weight (M dependence of hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · for dilute solutions in laminar flows was shown to follow a power law: hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ε c · ≈ Mw–k. An experimental study has been performed to investigate the onset of mechanical degradation in both laminar and turbulent flows and for both dilute and semi dilute polyethylene oxide aqueous solutions. It reveals that the exponent k strongly depends on the concentration and flow regimes and also on solvent quality. Results show that mechanical degradation mainly affects long chains, that it is favoured at high concentrations, under poor solvent conditions. They also evidence that the extensional viscosity at low strain rates decreases to the same extent as shear viscosities due to mechanical degradation. However, the decrease of the extensional viscous properties at high strain rates is much more pronounced. Les polymères hydrosolubles comme les polyacrylamides peuvent être utilisés en récupération assistée des hydrocarbures (Enhanced Oil Recovery (EOR par injection de polymère. Cette technique vise à augmenter la production de brut en le poussant du réservoir vers un puits producteur à l’aide d’une solution de polymère suffisamment visqueuse. Les polymères utilisés à cet effet ont des masses moléculaires supérieures à 106 g/mol, ce qui les rend sensibles à la dégradation. En raison

Enhanced Oil Recovery by a Horizontal Well Located Inside a Polymer Flood Pilot Récupération assistée des hydrocarbures par forage horizontal à l'intérieur d'un pilote d'injection de polymère

Directory of Open Access Journals (Sweden)

Foxonet F.

2006-11-01

configuration à 7 points inversée comportait un injecteur central entouré de 6 puits producteurs situés à 400 m de distance. On a procédé à l'injection d'une solution de polymère (de 1977 à 1983, puis d'eau. La section horizontale du puits CR 163 H est située à l'extrémité nord du pilote, à 350 m de l'injecteur, et suit à peu près la courbe du banc prévu. Son indice de productivité atteint près de 7 fois la moyenne des puits verticaux voisins. La coupe aqueuse a brusquement diminué en mars 1988, jusqu'en octobre 1988, puis s'est établie au même niveau que dans les puits environnants. Ce fait est manifestement dû au banc d'hydrocarbures créé par l'injection de polymère, qui fait du puits CR 163 H un outil efficace pour ce que l'on pourrait appeler Récupération géométriquement assistée des hydrocarbures .

Rational design of multifunctional devices based on molybdenum disulfide and graphene hybrid nanostructures

Energy Technology Data Exchange (ETDEWEB)

Lim, Yi Rang; Lee, Young Bum; Kim, Seong Ku; Kim, Seong Jun [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong, Post Office Box 107, Daejeon 305-600 (Korea, Republic of); Kim, Yooseok; Jeon, Cheolho [Nano-Surface Research Group, Korea Basic Science Institute, Daejeon, 302-333 (Korea, Republic of); Song, Wooseok, E-mail: wssong@krict.re.kr [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong, Post Office Box 107, Daejeon 305-600 (Korea, Republic of); Myung, Sung; Lee, Sun Sook; An, Ki-Seok [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong, Post Office Box 107, Daejeon 305-600 (Korea, Republic of); Lim, Jongsun, E-mail: jslim@krict.re.kr [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong, Post Office Box 107, Daejeon 305-600 (Korea, Republic of)

2017-01-15

Highlights: • We fabricated MoS{sub 2}-graphene hybrid thin films for multifunctional applications. • Large-area, uniform multilayer MoS{sub 2} was synthesized on TCVD-grown graphene. • The mobility and photocurrent of the hybrid devices were improved significantly. - Abstract: We rationally designed a new type of hybrid materials, molybdenum disulfide (MoS{sub 2}) synthesized by Mo pre-deposition followed by subsequent sulfurization process directly on thermal chemical vapor deposition (TCVD)-grown graphene, for applications in a multifunctional device. The synthesis of stoichiometric and uniform multilayer MoS{sub 2} and high-crystalline monolayer graphene was evaluated by X-ray photoelectron spectroscopy and Raman spectroscopy. To examine the electrical transport and photoelectrical properties of MoS{sub 2}-graphene hybrid films, field effect transistors (FETs) and visible-light photodetectors based on MoS{sub 2}-graphene were both fabricated. As a result, the extracted mobility for MoS{sub 2}-graphene hybrid FETs was two times higher than that of MoS{sub 2} FETs. In addition, the MoS{sub 2}-graphene photodetectors revealed a significant photocurrent with abrupt switching behavior under periodic illumination.

Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Polymers as Prototypical Semiconductors for High-Performance Field-Effect Transistors.

Science.gov (United States)

Li, Mengmeng; An, Cunbin; Pisula, Wojciech; Müllen, Klaus

2018-05-15

Donor-acceptor (D-A) conjugated polymers are of great interest as organic semiconductors, because they offer a rational tailoring of the electronic properties by modification of the donor and acceptor units. Nowadays, D-A polymers exhibit field-effect mobilities on the order of 10 -2 -10 0 cm 2 V -1 s -1 , while several examples showed a mobility over 10 cm 2 V -1 s -1 . The development of cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers one decade ago represents an important step toward high-performance organic semiconductors for field-effect transistors. The significant rise in field-effect mobility of CDT-BTZ in comparison to the existing D-A polymers at that time opened the door to a new research field with a large number of novel D-A systems. From this point, the device performance of CDT-BTZ was gradually improved by a systematic optimization of the synthesis and polymer structure as well as by an efficient solution processing into long-range ordered thin films. The key aspect was a comprehensive understanding of the relation between polymer structure and solid-state organization. Due to their fundamental role for the field of D-A polymers in general, this Account will for the first time explicitly focus on prototypical CDT-BTZ polymers, while other reviews provide an excellent general overview on D-A polymers. The first part of this Account discusses strategies for improving the charge carrier transport, focusing on chemical aspects. Improved synthesis as an essential stage toward high purity, and high molecular weight is a prerequisite for molecular order. The modification of substituents is a further crucial feature to tune the CDT-BTZ packing and self-assembly. Linear alkyl side chains facilitate intermolecular π-stacking interactions, while branched ones increase solubility and alter the polymer packing. Additional control over the supramolecular organization of CDT-BTZ polymers is introduced by alkenyl substituents via their cis

Psychology and the Rationality of Emotion*

Science.gov (United States)

Clore, Gerald L.

2014-01-01

Questions addressed by recent psychological research on emotion include questions about how thought shapes emotion and how emotion, in turn, shapes thought. Research on emotion and cognition paints a somewhat different picture than that seen in traditional discussions of passion and reason. This article reviews several aspects of this research, concentrating specifically on three views of rationality: Rationality as Process, Rationality as Product, and Rationality as Outcome. PMID:25125770

The political economy of rationing health care in England and the US: the 'accidental logics' of political settlements.

Science.gov (United States)

Bevan, Gwyn; Brown, Lawrence D

2014-07-01

This article considers how the 'accidental logics' of political settlements for the English National Health Service (NHS) and the Medicare and Medicaid programmes in the United States have resulted in different institutional arrangements and different implicit social contracts for rationing, which we define to be the denial of health care that is beneficial but is deemed to be too costly. This article argues that rationing is designed into the English NHS and designed out of US Medicare; and compares rationing for the elderly in the United States and in England for acute care, care at the end of life, and chronic care.

DISTRIBUTED RC NETWORKS WITH RATIONAL TRANSFER FUNCTIONS,

Science.gov (United States)

A distributed RC circuit analogous to a continuously tapped transmission line can be made to have a rational short-circuit transfer admittance and...one rational shortcircuit driving-point admittance. A subcircuit of the same structure has a rational open circuit transfer impedance and one rational ...open circuit driving-point impedance. Hence, rational transfer functions may be obtained while considering either generator impedance or load

Rational Design of in Vivo Tau Tangle-Selective Near-Infrared Fluorophores: Expanding the BODIPY Universe.

Science.gov (United States)

Verwilst, Peter; Kim, Hye-Ri; Seo, Jinho; Sohn, Nak-Won; Cha, Seung-Yun; Kim, Yeongmin; Maeng, Sungho; Shin, Jung-Won; Kwak, Jong Hwan; Kang, Chulhun; Kim, Jong Seung

2017-09-27

The elucidation of the cause of Alzheimer's disease remains one of the greatest questions in neurodegenerative research. The lack of highly reliable low-cost sensors to study the structural changes in key proteins during the progression of the disease is a contributing factor to this lack of insight. In the current work, we describe the rational design and synthesis of two fluorescent BODIPY-based probes, named Tau 1 and Tau 2. The probes were evaluated on the molecular surface formed by a fibril of the PHF6 ( 306 VQIVYK 311 ) tau fragment using molecular docking studies to provide a potential molecular model to rationalize the selectivity of the new probes as compared to a homologous Aβ-selective probe. The probes were synthesized in a few steps from commercially available starting products and could thus prove to be highly cost-effective. We demonstrated the excellent photophysical properties of the dyes, such as a large Stokes shift and emission in the near-infrared window of the electromagnetic spectrum. The probes demonstrated a high selectivity for self-assembled microtubule-associated protein tau (Tau protein), in both solution and cell-based experiments. Moreover, the administration to an acute murine model of tauopathy clearly revealed the staining of self-assembled hyperphosphorylated tau protein in pathologically relevant hippocampal brain regions. Tau 1 demonstrated efficient blood-brain barrier penetrability and demonstrated a clear selectivity for tau tangles over Aβ plaques, as well as the capacity for in vivo imaging in a transgenic mouse model. The current work could open up avenues for the cost-effective monitoring of the tau protein aggregation state in animal models as well as tissue staining. Furthermore, these fluorophores could serve as the basis for the development of clinically relevant sensors, for example based on PET imaging.

A polymer driveshaft for use in orbital and rotational atherectomy

Science.gov (United States)

Grothe, Preston Lee

Driveshafts used in atherectomy medical devices are often comprised of coiled or braided metal wires. These constructions are designed to tolerate delivery through tortuous vessels and can endure high speed rotation used during activation of the atherectomy treatment. This research investigated polymer driveshaft designs, which were comprised of polymer inner and outer layers, and coiled or braided stainless steel wires. The polymer driveshaft materials included polyimide, nylon 12, and polytetrafluoroethylene (PTFE). Mechanical testing of polymer driveshafts was conducted to determine material response in bending, tension, compression, and torsion. The polymer driveshaft test results were then compared with current coiled metal wire driveshaft constructions. The investigation identified polymer driveshaft options that could feasibly work in an atherectomy application.

Morphology design of microporous organic polymers and their potential applications: an overview

Institute of Scientific and Technical Information of China (English)

Qingyin Li; Shumaila Razzaque; Shangbin Jin; Bien Tan

2017-01-01

Microporous organic polymers (MOPs) have attracted considerable research interest because of their well-defined porosity,high surface area,lightweight nature,and tunable surface chemistry.The morphology of MOPs are demonstrated to play a significant role in various applications although limited examples manifesting the importance of the MOP morphology in numerous applications have been reported.This review summarizes the recent progress in the design of MOPs using different techniques,including hard and soft template and direct synthesis methods.In addition,their applications,which possibly attribute to their shape,are discussed.Furthermore,the advantages and disadvantages of different methods are discussed,as well as their development and future challenges.

Final Report: Rational Design of Wide Band Gap Buffer Layers for High-Efficiency Thin-Film Photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Lordi, Vincenzo [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-09-30

The main objective of this project is to enable rational design of wide band gap buffer layer materials for CIGS thin-film PV by building understanding of the correlation of atomic-scale defects in the buffer layer and at the buffer/absorber interface with device electrical properties. Optimized wide band gap buffers are needed to reduce efficiency loss from parasitic absorption in the buffer. The approach uses first-principles materials simulations coupled with nanoscale analytical electron microscopy as well as device electrical characterization. Materials and devices are produced by an industrial partner in a manufacturing line to maximize relevance, with the goal of enabling R&D of new buffer layer compositions or deposition processes to push device efficiencies above 21%. Cadmium sulfide (CdS) is the reference material for analysis, as the prototypical high-performing buffer material.

Rational design of single-ion magnets and spin qubits based on mononuclear lanthanoid complexes.

Science.gov (United States)

Baldoví, José J; Cardona-Serra, Salvador; Clemente-Juan, Juan M; Coronado, Eugenio; Gaita-Ariño, Alejandro; Palii, Andrew

2012-11-19

Here we develop a general approach to calculating the energy spectrum and the wave functions of the low-lying magnetic levels of a lanthanoid ion submitted to the crystal field created by the surrounding ligands. This model allows us to propose general criteria for the rational design of new mononuclear lanthanoid complexes behaving as single-molecule magnets (SMMs) or acting as robust spin qubits. Three typical environments exhibited by these metal complexes are considered, namely, (a) square antiprism, (b) triangular dodecahedron, and (c) trigonal prism. The developed model is used to explain the properties of some representative examples showing these geometries. Key questions in this area, such as the chemical tailoring of the superparamagnetic energy barrier, tunneling gap, or spin relaxation time, are discussed. Finally, in order to take into account delocalization and/or covalent effects of the ligands, this point-charge model is complemented with ab initio calculations, which provide accurate information on the charge distribution around the metal, allowing for an explanation of the SMM behavior displayed by some sandwich-type organometallic compounds.

Production and Energy Partition of Lactating Dairy Goats Fed Rations Containing Date Fruit Waste

Directory of Open Access Journals (Sweden)

E. Yuniarti

2016-04-01

Full Text Available Dates fruit waste (DFW is a by-product of dates juice industry that contains high energy. So, it is suitable for an energy source in dairy goat ration. This study was conducted to observe the effect of DFW utilization in the ration on energy partition and productivity of lactating dairy goats. The experimental design was randomized block design using 9 primiparous lactating dairy goats. There were three types of ration as treatments used in this study, i.e. R0= 35% forage + 65% concentrate, R1= 35% forage + 55% concentrate + 10% DFW, and R2= 35% forage + 45% concentrate + 20% DFW. Data were analyzed using ANOVA and polynomial orthogonal test. The evaluated variables were dry matter intake (DMI, energy partition including energy intake, digestible and metabolizable energy, fecal and urine energy, energy in methane gas, and energy in milk, milk production and quality. The results showed that the linear decreased of DMI, energy intake, digestible energy, metabolizable energy, and urine energy with the increased of DFW level in the rations. The use of 10% DFW (R1 showed the lowest energy loss through feces and methane gas of all treatments about 1089.57 kcal/head/d and 2.36 kcal/head/d, respectively. The use of DFW did not affect energy retention in milk. The utilization of DFW in ration did not significantly prevent the decline of milk production and milk quality. It can be concluded that DFW can be used as an alternative feed for the lactating dairy goat up to 10% in the ration.

Rational design and validation of an anti-protein kinase C active-state specific antibody based on conformational changes.

Science.gov (United States)

Pena, Darlene Aparecida; Andrade, Victor Piana de; Silva, Gabriela Ávila Fernandes; Neves, José Ivanildo; Oliveira, Paulo Sergio Lopes de; Alves, Maria Julia Manso; Devi, Lakshmi A; Schechtman, Deborah

2016-02-25

Protein kinase C (PKC) plays a regulatory role in key pathways in cancer. However, since phosphorylation is a step for classical PKC (cPKC) maturation and does not correlate with activation, there is a lack of tools to detect active PKC in tissue samples. Here, a structure-based rational approach was used to select a peptide to generate an antibody that distinguishes active from inactive cPKC. A peptide conserved in all cPKCs, C2Cat, was chosen since modeling studies based on a crystal structure of PKCβ showed that it is localized at the interface between the C2 and catalytic domains of cPKCs in an inactive kinase. Anti-C2Cat recognizes active cPKCs at least two-fold better than inactive kinase in ELISA and immunoprecipitation assays, and detects the temporal dynamics of cPKC activation upon receptor or phorbol stimulation. Furthermore, the antibody is able to detect active PKC in human tissue. Higher levels of active cPKC were observed in the more aggressive triple negative breast cancer tumors as compared to the less aggressive estrogen receptor positive tumors. Thus, this antibody represents a reliable, hitherto unavailable and a valuable tool to study PKC activation in cells and tissues. Similar structure-based rational design strategies can be broadly applied to obtain active-state specific antibodies for other signal transduction molecules.

Max Weber's Types of Rationality: Cornerstones for the Analysis of Rationalization Processes in History.

Science.gov (United States)

Kalberg, Stephen

1980-01-01

Explores rationality in Max Weber's works and identifies four types of rationality which play major roles in his writing--practical, theoretical, substantive, and formal. Implications for society and education are discussed. (DB)

Naphthalene Diimide Based n-Type Conjugated Polymers as Efficient Cathode Interfacial Materials for Polymer and Perovskite Solar Cells.

Science.gov (United States)

Jia, Tao; Sun, Chen; Xu, Rongguo; Chen, Zhiming; Yin, Qingwu; Jin, Yaocheng; Yip, Hin-Lap; Huang, Fei; Cao, Yong

2017-10-18

A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure-performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.

The concept of rational suicide.

Science.gov (United States)

Mayo, D J

1986-05-01

Suicide has been condemned in our culture in one way or another since Augustine offered theological arguments against it in the sixth century. More recently, theological condemnation has given way to the view that suicidal behavior must always be symptomatic of emotional disturbance and mental illness. However, suicide has not always been viewed so negatively. In other times and cultures, it has been held that circumstances might befall a person in which suicide would be a perfectly rational course of action, in the same sense that any other course of action could be rational: that it could be sensible, i.e., defensible by good reasons, or that it could be in keeping with the agent's fundamental interests. Indiscriminate use of modern life-sustaining technologies has renewed interest in the possibility of rational suicide. Today proponents of rational suicide tend to equate the rationality of suicide with the competence of the decision to commit suicide.

Experiential versus rational training: a comparison of student attitudes toward homosexuality.

Science.gov (United States)

Guth, Lorraine J; Lopez, David F; Rojas, Julio; Clements, Kimberly D; Tyler, J Michael

2004-01-01

Based on Epstein's (1994a) cognitive-experiential self-theory, two new training interventions were designed to teach students about gay, lesbian and bisexual issues. The efficacy of these theoretically based interventions was assessed in a short-term (7-week, three occasion) longitudinal study. Fifty undergraduate psychology students were randomly assigned to one of three treatment groups: Rational Training, Experiential Training, or Control Group. A residualized change score procedure was used to analyze change in levels of sexual prejudice and affect across the three types of measurement (pre-test, post-test, and follow-up). A 3 (Rational Training, Experiential Training, Control Group) x 2 (Low Sexual Prejudice, High Sexual Prejudice) MANOVA revealed that after the training, participants in the Experiential Group (affective training) had more accepting attitudes toward homosexuality compared to the Control Group. In addition, participants in the Experiential Group experienced more positive affect compared to the Rational and Control Groups and experienced more negative affect compared to the Rational Group. Findings are discussed and suggestions for future research are provided.

Rational Ligand Design for U(VI) and Pu(IV)

International Nuclear Information System (INIS)

Szigethy, Geza

2009-01-01

Nuclear power is an attractive alternative to hydrocarbon-based energy production at a time when moving away from carbon-producing processes is widely accepted as a significant developmental need. Hence, the radioactive actinide power sources for this industry are necessarily becoming more widespread, which is accompanied by the increased risk of exposure to both biological and environmental systems. This, in turn, requires the development of technology designed to remove such radioactive threats efficiently and selectively from contaminated material, whether that be contained nuclear waste streams or the human body. Raymond and coworkers (University of California, Berkeley) have for decades investigated the interaction of biologically-inspired, hard Lewis-base ligands with high-valent, early-actinide cations. It has been established that such ligands bind strongly to the hard Lewis-acidic early actinides, and many poly-bidentate ligands have been developed and shown to be effective chelators of actinide contaminants in vivo. Work reported herein explores the effect of ligand geometry on the linear U(IV) dioxo dication (uranyl, UO 2 2+ ). The goal is to utilize rational ligand design to develop ligands that exhibit shape selectivity towards linear dioxo cations and provides thermodynamically favorable binding interactions. The uranyl complexes with a series of tetradentate 3-hydroxy-pyridin-2-one (3,2-HOPO) ligands were studied in both the crystalline state as well as in solution. Despite significant geometric differences, the uranyl affinities of these ligands vary only slightly but are better than DTPA, the only FDA-approved chelation therapy for actinide contamination. The terepthalamide (TAM) moiety was combined into tris-beidentate ligands with 1,2- and 3,2-HOPO moieties were combined into hexadentate ligands whose structural preferences and solution thermodynamics were measured with the uranyl cation. In addition to achieving coordinative saturation, these

Rational Ligand Design for U(VI) and Pu(IV)

Energy Technology Data Exchange (ETDEWEB)

Szigethy, Geza [Univ. of California, Berkeley, CA (United States)

2009-08-12

Nuclear power is an attractive alternative to hydrocarbon-based energy production at a time when moving away from carbon-producing processes is widely accepted as a significant developmental need. Hence, the radioactive actinide power sources for this industry are necessarily becoming more widespread, which is accompanied by the increased risk of exposure to both biological and environmental systems. This, in turn, requires the development of technology designed to remove such radioactive threats efficiently and selectively from contaminated material, whether that be contained nuclear waste streams or the human body. Raymond and coworkers (University of California, Berkeley) have for decades investigated the interaction of biologically-inspired, hard Lewis-base ligands with high-valent, early-actinide cations. It has been established that such ligands bind strongly to the hard Lewis-acidic early actinides, and many poly-bidentate ligands have been developed and shown to be effective chelators of actinide contaminants in vivo. Work reported herein explores the effect of ligand geometry on the linear U(IV) dioxo dication (uranyl, UO₂ ²⁺). The goal is to utilize rational ligand design to develop ligands that exhibit shape selectivity towards linear dioxo cations and provides thermodynamically favorable binding interactions. The uranyl complexes with a series of tetradentate 3-hydroxy-pyridin-2-one (3,2-HOPO) ligands were studied in both the crystalline state as well as in solution. Despite significant geometric differences, the uranyl affinities of these ligands vary only slightly but are better than DTPA, the only FDA-approved chelation therapy for actinide contamination. The terepthalamide (TAM) moiety was combined into tris-beidentate ligands with 1,2- and 3,2-HOPO moieties were combined into hexadentate ligands whose structural preferences and solution thermodynamics were measured with the uranyl cation. In addition to achieving coordinative

RATGRAPH: Computer Graphing of Rational Functions.

Science.gov (United States)

Minch, Bradley A.

1987-01-01

Presents an easy-to-use Applesoft BASIC program that graphs rational functions and any asymptotes that the functions might have. Discusses the nature of rational functions, graphing them manually, employing a computer to graph rational functions, and describes how the program works. (TW)

Rational design and evaluation of HBsAg polymeric nanoparticles as antigen delivery carriers.

Science.gov (United States)

Dewangan, Hitesh Kumar; Pandey, Tarun; Maurya, Lakshmi; Singh, Sanjay

2018-05-01

The present work is focused on the development and evaluation of single dose sustained-release Hepatitis B surface antigen (HBsAg) loaded nanovaccine for Hepatitis B. The conventional treatment suffers from repeated administration and hence requires a booster dose. Therefore, polymeric nanovaccine of HBsAg was developed by double emulsion solvent evaporation technique, utilizing central composite design for formulation optimization. The effects of independent variables (like polymer amount, stabilizer concentration, aqueous/organic phase ratio and homogenizer speed) were also studied on critical quality attributes like particle size and entrapment efficiency. Nanovaccine was characterized in terms of physicochemical parameters, release, internalization and in vivo immunological evaluation in BALB/c mice after administration by different routes such as oral, sub-cutaneous, nasal and intramuscular. The designed nanovaccine demonstrated nanometric size with smooth surface, negative zeta potential, maximum entrapment, sustained release and better internalization in macrophage and MRC-5 cell line. The immune-stimulating activity of nanovaccine administered by different routes was evaluated by measuring anti-HBsAg titre like specific immunoglobulin IgG and IgA response and cytokine level (interleukin-2, interferon-Y) measurement. The results indicated that the nanovaccine administered by intramuscular route produced better humoral as well as cellular responses and potential carriers for antigen delivery at single dose administration via intramuscular route. Copyright © 2018 Elsevier B.V. All rights reserved.

F-theory and all things rational: surveying U(1) symmetries with rational sections

International Nuclear Information System (INIS)

Lawrie, Craig; Schäfer-Nameki, Sakura; Wong, Jin-Mann

2015-01-01

We study elliptic fibrations for F-theory compactifications realizing 4d and 6d supersymmetric gauge theories with abelian gauge factors. In the fibration these U(1) symmetries are realized in terms of additional rational section. We obtain a universal characterization of all the possible U(1) charges of matter fields by determining the corresponding codimension two fibers with rational sections. In view of modelling supersymmetric Grand Unified Theories, one of the main examples that we analyze are U(1) symmetries for SU(5) gauge theories with 5̄ and 10 matter. We use a combination of constraints on the normal bundle of rational curves in Calabi-Yau three- and four-folds, as well as the splitting of rational curves in the fibers in codimension two, to determine the possible configurations of smooth rational sections. This analysis straightforwardly generalizes to multiple U(1)s. We study the flops of such fibers, as well as some of the Yukawa couplings in codimension three. Furthermore, we carry out a universal study of the U(1)-charged GUT singlets, including their KK-charges, and determine all realizations of singlet fibers. By giving vacuum expectation values to these singlets, we propose a systematic way to analyze the Higgsing of U(1)s to discrete gauge symmetries in F-theory.

"Leaky" Rationality: How Research on Behavioral Decision Making Challenges Normative Standards of Rationality.

Science.gov (United States)

Keys, Daniel J; Schwartz, Barry

2007-06-01

For more than 30 years, decision-making research has documented that people often violate various principles of rationality, some of which are so fundamental that theorists of rationality rarely bother to state them. We take these characteristics of decision making as a given but argue that it is problematic to conclude that they typically represent departures from rationality. The very psychological processes that lead to "irrational" decisions (e.g., framing, mental accounting) continue to exert their influence when one experiences the results of the decisions. That is, psychological processes that affect decisions may be said also to "leak" into one's experience. The implication is that formal principles of rationality do not provide a good enough normative standard against which to assess decision making. Instead, what is needed is a substantive theory of rationality-one that takes subjective experience seriously, considers both direct and indirect consequences of particular decisions, considers how particular decisions fit into life as a whole, and considers the effects of decisions on others. Formal principles may play a role as approximations of the substantive theory that can be used by theorists and decision makers in cases in which the formal principles can capture most of the relevant considerations and leakage into experience is negligible. © 2007 Association for Psychological Science.

Popper, Rationality and the Possibility of Social Science

Directory of Open Access Journals (Sweden)

Danny Frederick

2013-02-01

Full Text Available Social science employs teleological explanations which depend upon the rationality principle, according to which people exhibit instrumental rationality. Popper points out that people also exhibit critical rationality, the tendency to stand back from, and to question or criticise, their views. I explain how our critical rationality impugns the explanatory value of the rationality principle and thereby threatens the very possibility of social science. I discuss the relationship between instrumental and critical rationality and show how we can reconcile our critical rationality with the possibility of social science if we invoke Popper’s conception of limited rationality and his indeterminism.

Entangled Polymer Melts in Extensional Flow

DEFF Research Database (Denmark)

Hengeller, Ludovica

Many commercial materials derived from synthetic polymers exhibit a complex response under different processing operations such as fiber formation, injection moulding,film blowing, film casting or coatings. They can be processed both in the solid or in the melted state. Often they may contain two...... or more different polymers in addition to additives, fillers or solvents in order to modify the properties of the final product. Usually, it is also desired to improve the processability. For example the supplement of a high molecular weight component improves the stability in elongational flows....... Understanding the behaviour of polymer melts and solutions in complex non-linearflows is crucial for the design of polymeric materials and polymer processes. Through rheological characterization, in shear and extensional flow, of model polymer systems,i.e. narrow molar mass distribution polymer melts...

Ethics of rationing of nursing care.

Science.gov (United States)

Rooddehghan, Zahra; Yekta, Zohreh Parsa; Nasrabadi, Alireza N

2016-09-21

Rationing of various needed services, for example, nursing care, is inevitable due to unlimited needs and limited resources. Rationing of nursing care is considered an ethical issue since it requires judgment about potential conflicts between personal and professional values. The present research sought to explore aspects of rationing nursing care in Iran. This study applied qualitative content analysis, a method to explore people's perceptions of everyday life phenomena and interpret the subjective content of text data. Data collection was performed through in-depth, unstructured, face-to-face interviews with open-ended questions. The study population included Iranian nurses of all nursing positions, from clinical nurses to nurse managers. Purposive sampling was employed to select 15 female and 3 male nurses (11 clinical nurses, 3 supervisors, 1 matron, 1 nurse, and 2 members of the Nursing Council) working in hospitals of three cities in Iran. The study protocol was approved by Tehran University of Medical Sciences (91D1302870). Written informed consent was also obtained from all participants. According to the participants, rationing of nursing care consisted of two categories, that is, causes of rationing and consequences of rationing. The first category comprised three subcategories, namely, patient needs and demands, routinism, and VIP patients. The three subcategories forming the second category were missed nursing care, patient dissatisfaction, and nurses' feeling of guilt. Levels at which healthcare practices are rationed and clarity of the rationing are important structural considerations in the development of an equal, appropriate, and ethical healthcare system. Moreover, the procedure of rationing is critical as it not only influences people's lives but also reflects the values that dominate in the society. Therefore, in order to minimize the negative consequences of rationing of nursing care, further studies on the ethical dimensions of this phenomenon

Shape memory polymer cellular solid design for medical applications

International Nuclear Information System (INIS)

De Nardo, L; Bertoldi, S; Tanzi, M C; Farè, S; Haugen, H J

2011-01-01

Shape memory polymers (SMPs) are an emerging class of active materials whose response can be easily tailored via modifications of the molecular parameters and optimization of the transformation processes. In this work, we originally demonstrated that a correct coupling of polymer transformation processes (co-extrusion with chemical blowing agents, salt co-extrusion/particulate leaching, solvent casting/particulate leaching) and SMPs allows one to obtain porous structures with a broad spectrum of morphological properties resulting in tunable thermo-mechanical and shape recovery properties. Such a wide range of properties could fulfil the specifications of medical applications in which the use of SMP-based foams can be envisaged

Casebook on rationalization of power use

International Nuclear Information System (INIS)

1986-06-01

This book introduces the cases on rationalization of power use, which is divided into four parts. The first part refers the goal of rational use of energy and the result. The second part deals with the excellent cases on rationalization of domestic power use, which list the name of the company, hotel and factory according to the field such as building, textile and food. The third part contains the outstanding cases on rationalization of foreign power use, which were listed by the specific way to reduce electricity use each section. The fourth part is comprised of two chapters, which deals with the cases of domestic technical data and foreign technical data for rational use of energy.

Chemical Markup, XML and the World-Wide Web. 8. Polymer Markup Language.

Science.gov (United States)

Adams, Nico; Winter, Jerry; Murray-Rust, Peter; Rzepa, Henry S

2008-11-01

Polymers are among the most important classes of materials but are only inadequately supported by modern informatics. The paper discusses the reasons why polymer informatics is considerably more challenging than small molecule informatics and develops a vision for the computer-aided design of polymers, based on modern semantic web technologies. The paper then discusses the development of Polymer Markup Language (PML). PML is an extensible language, designed to support the (structural) representation of polymers and polymer-related information. PML closely interoperates with Chemical Markup Language (CML) and overcomes a number of the previously identified challenges.

Rational Design of a New Trypanosoma rangeli Trans-Sialidase for Efficient Sialylation of Glycans

DEFF Research Database (Denmark)

Jers, Carsten; Michalak, Malwina; Larsen, Dorte Møller

2014-01-01

This paper reports rational engineering of Trypanosoma rangeli sialidase to develop an effective enzyme for a potentially important type of reactivity: production of sialylated prebiotic glycans. The Trypanosoma cruzi trans-sialidase and the homologous T. rangeli sialidase has previously been use...

From rational creatures to the rational Creator: ancient and patristic analogies of the “fine-tuning” argument

Directory of Open Access Journals (Sweden)

Alexey Fokin

2017-12-01

Full Text Available In this article the author deals with the proofs of the existence of God, based on the fact of the presence of rational beings in the world. These proofs can be found in Greek and Roman Classical philosophy and early Patristics, and can be viewed as an analogue of the modern “fine-tuning argument”. The author considers the origins and development of this argument in the Greek and Roman philosophy: in Socrates, Plato, Cicero, Sextus Empiricus, and especially the Stoics, who gave to the argument a logical form, based on the relationship between “the parts and the whole”: if the world as a whole produces and contains rational beings as its parts, it should also be rational or contain a rational principle that generates all its parts and governs them, just as human soul governs human body. The correction of this argument was proposed by Sextus Empiricus, who introduced the concept of "spermatic logoi", or rational principles, to explain the generation of the rational beings by the world, so that if the world contains the spermatic logoi of rational and living beings, then the world as a whole is also rational. The author also investigates the reception of the argument based on the existence of rational beings in the world in Latin Patristics: in Minucius Felix, Tertullian and especially Lactantius, in whom this argument has reached the climax of its development. At the same time it was shown, that the ancient argument has undergone a transformation from the postulation of the rationality of the world as a whole or its equation with God himself to a genuine proof of the existence of the one God who is the Creator both of the world and human beings, superior to the both as the all-powerful and transcendent Mind.

Thermodynamic dissection of the binding energetics of proline-rich peptides to the Abl-SH3 domain: implications for rational ligand design.

Science.gov (United States)

Palencia, Andrés; Cobos, Eva S; Mateo, Pedro L; Martínez, Jose C; Luque, Irene

2004-02-13

The inhibition of the interactions between SH3 domains and their targets is emerging as a promising therapeutic strategy. To date, rational design of potent ligands for these domains has been hindered by the lack of understanding of the origins of the binding energy. We present here a complete thermodynamic analysis of the binding energetics of the p41 proline-rich decapeptide (APSYSPPPPP) to the SH3 domain of the c-Abl oncogene. Isothermal titration calorimetry experiments have revealed a thermodynamic signature for this interaction (very favourable enthalpic contributions opposed by an unfavourable binding entropy) inconsistent with the highly hydrophobic nature of the p41 ligand and the Abl-SH3 binding site. Our structural and thermodynamic analyses have led us to the conclusion, having once ruled out any possible ionization events or conformational changes coupled to the association, that the establishment of a complex hydrogen-bond network mediated by water molecules buried at the binding interface is responsible for the observed thermodynamic behaviour. The origin of the binding energetics for proline-rich ligands to the Abl-SH3 domain is further investigated by a comparative calorimetric analysis of a set of p41-related ligands. The striking effects upon the enthalpic and entropic contributions provoked by conservative substitutions at solvent-exposed positions in the ligand confirm the complexity of the interaction. The implications of these results for rational ligand design are discussed.

Filament stretching rheometry of polymer melts

DEFF Research Database (Denmark)

Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

2005-01-01

The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

Rationing medical education | Walsh | African Health Sciences

African Journals Online (AJOL)

Even though some stakeholders in medical education might be taken aback at the prospect of rationing, the truth is that rationing has always occurred in one form or another in medical education and in healthcare more broadly. Different types of rationing exist in healthcare professional education. For example rationing may ...

A Thieno[2,3-b]pyridine-Flanked Diketopyrrolopyrrole Polymer as an n-Type Polymer Semiconductor for All-Polymer Solar Cells and Organic Field-Effect Transistors

KAUST Repository

Chen, Hung-Yang

2017-12-28

A novel fused heterocycle-flanked diketopyrrolopyrrole (DPP) monomer, thieno[2,3-b]pyridine diketopyrrolopyrrole (TPDPP), was designed and synthesized. When copolymerized with 3,4-difluorothiophene using Stille coupling polymerization, the new polymer pTPDPP-TF possesses a highly planar conjugated polymer backbone due to the fused thieno[2,3-b]pyridine flanking unit that effectively alleviates the steric hindrance with both the central DPP core and the 3,4-difluorothiophene repeat unit. This new polymer exhibits a high electron affinity (EA) of −4.1 eV and was successfully utilized as an n-type polymer semiconductor for applications in organic field-effect transistors (OFETs) and all polymer solar cells. A promising n-type charge carrier mobility of 0.1 cm2 V–1 s–1 was obtained in bottom-contact, top-gate OFETs, and a power conversion efficiency (PCE) of 2.72% with a high open-circuit voltage (VOC) of 1.04 V was achieved for all polymer solar cells using PTB7-Th as the polymer donor.

A Thieno[2,3-b]pyridine-Flanked Diketopyrrolopyrrole Polymer as an n-Type Polymer Semiconductor for All-Polymer Solar Cells and Organic Field-Effect Transistors

KAUST Repository

Chen, Hung-Yang; Nikolka, Mark; Wadsworth, Andrew; Yue, Wan; Onwubiko, Ada; Xiao, Mingfei; White, Andrew J. P.; Baran, Derya; Sirringhaus, Henning; McCulloch, Iain

2017-01-01

A novel fused heterocycle-flanked diketopyrrolopyrrole (DPP) monomer, thieno[2,3-b]pyridine diketopyrrolopyrrole (TPDPP), was designed and synthesized. When copolymerized with 3,4-difluorothiophene using Stille coupling polymerization, the new polymer pTPDPP-TF possesses a highly planar conjugated polymer backbone due to the fused thieno[2,3-b]pyridine flanking unit that effectively alleviates the steric hindrance with both the central DPP core and the 3,4-difluorothiophene repeat unit. This new polymer exhibits a high electron affinity (EA) of −4.1 eV and was successfully utilized as an n-type polymer semiconductor for applications in organic field-effect transistors (OFETs) and all polymer solar cells. A promising n-type charge carrier mobility of 0.1 cm2 V–1 s–1 was obtained in bottom-contact, top-gate OFETs, and a power conversion efficiency (PCE) of 2.72% with a high open-circuit voltage (VOC) of 1.04 V was achieved for all polymer solar cells using PTB7-Th as the polymer donor.

Biomimetic oligosaccharide and peptide surfactant polymers designed for cardiovascular biomaterials

Science.gov (United States)

Ruegsegger, Mark Andrew

A common problem associated with cardiovascular devices is surface induced thrombosis initiated by the rapid, non-specific adsorption of plasma proteins onto the biomaterial surface. Control of the initial protein adsorption is crucial to achieve the desired longevity of the implanted biomaterial. The cell membrane glycocalyx acts as a non-thrombogenic interface through passive (dense oligosaccharide structures) and active (ligand/receptor interactions) mechanisms. This thesis is designed to investigate biomimicry of the cell glycocalyx to minimize non-specific protein adsorption and promote specific ligand/receptor interactions. Biomimetic macromolecules were designed through the molecular-scale engineering of polymer surfactants, utilizing a poly(vinyl amine) (PVAm) backbone to which hydrophilic (dextran, maltose, peptide) and hydrophobic alkyl (hexanoyl or hexanal) chains are simultaneously attached. The structure was controlled through the molar feed ratio of hydrophobic-to-hydrophilic groups, which also provided control of the solution and surface-active properties. To mimic passive properties, a series of oligomaltose surfactants were synthesized with increasing saccharide length (n = 2, 7, 15 where n is number of glucose units) to investigate the effect of coating height on protein adsorption. The surfactants were characterized by infra red (IR) and nuclear magnetic resonance (NMR) spectroscopies for structural properties and atomic force microscopy (AFM) and contact angle goniometry for surface activity. Protein adsorption under dynamic flow (5 dyn/cm2) was reduced by 85%--95% over the bare hydrophobic substrate; platelet adhesion dropped by ˜80% compared to glass. Peptide ligands were incorporated into the oligosaccharide surfactant to promote functional activity of the passive coating. The surfactants were synthesized to contain 0%, 25%, 50%, 75%, and 100% peptide ligand density and were stable on hydrophobic surfaces. The peptide surface density was

Rationality and antiemotionality as a risk factor for cancer: concept differentiation.

Science.gov (United States)

van der Ploeg, H M; Kleijn, W C; Mook, J; van Donge, M; Pieters, A M; Leer, J W

1989-01-01

Control and repression of emotions may be coping styles or personality characteristics found more often in patients with cancer than in other patients and healthy subjects. Previous research indicated a possible relationship between high scores on a 'rationality and antiemotionality' scale and cancer. In the two studies reported, the psychometric properties of this scale and the meaning of the concept as a personality variable related to the control of emotions were investigated. It was found that the internal consistency of the scale could be improved by re-designing it into a personality inventory. Factor analysis repeatedly yielded more than one factor, indicating the complexity of the concept. 'Rationality and antiemotionality' seems related to the control, suppression or repression of anger. Our findings tentatively support the view that rationality and antiemotionality may be an important distinctive personality characteristic in patients with cancer.

Semi-crystalline photovoltaic polymers with siloxane-terminated hybrid side-chains

Institute of Scientific and Technical Information of China (English)

Yuxiang Li; Seyeong Song; Song Yi Park; Jin Young Kim; Han Young Woo

2017-01-01

Three types of semi-cry stalline photovoltaic polymers were synthesized by incorporating a siloxane-terminated organic/inorganic hybrid side-chain and changing the number of fluorine substituents.A branch point away from a polymer main backbone in the siloxane-containing side-chains and the intra-and/or interchain noncovalent coulombic interactions enhance a chain planarity and facile interchain organization.The resulting polymers formed strongly agglomerated films with high roughness,suggesting strong intermolecular interactions.The optical band gap of ca.1.7 eV was measured for all polymers with a pronounced shoulder peak due to tight π-π stacking.With increasing the fluorine substituents,the frontier energy levels decreased and preferential face-on orientation was observed.The siloxane-terminated side-chains and fluorine substitution promoted the intermolecular packing,showing well resolved lamellar scatterings up to（300） for this series of polymers in the grazing incidence wide angle X-ray scattering measurements.The PPsiDTBT,PPsiDTFBT and PPsiDT2 FBT devices showed a power conversion efficiency of 3.16%,4.40%and 5.65%,respectively,by blending with PC71BM.Langevin-type bimolecular charge recombination was similar for three polymeric solar cells.The main loss in the photocurrent generation for PPsiDTBT:PC71BM was interpreted to originate from the trap assisted charge recombination by measuring light-intensity dependent short-circuit current density(JSC) and open-circuit voltage(VOc).Our results provide a new insight into the rational selection of solubilizing substituents for optimizing crystalline interchain packing with appropriate miscibility with PC71 BM for further optimizing polymer solar cells.

Semi-crystalline photovoltaic polymers with siloxane-terminated hybrid side-chains

Institute of Scientific and Technical Information of China (English)

Yuxiang Li; Seyeong Song; Song Yi Park; Jin Young Kim; Han Young Woo

2017-01-01

Three types of semi-crystalline photovoltaic polymers were synthesized by incorporating a siloxane-terminated organic/inorganic hybrid side-chain and changing the number of fluorine substituents.A branch point away from a polymer main backbone in the siloxane-containing side-chains and the intra-and/or interchain noncovalent coulombic interactions enhance a chain planarity and facile interchain organization.The resulting polymers formed strongly agglomerated films with high roughness,suggesting strong intermolecular interactions.The optical band gap of ca.1.7 eV was measured for all polymers with a pronounced shoulder peak due to tight π-π stacking.With increasing the fluorine substituents,the frontier energy levels decreased and preferential face-on orientation was observed.The siloxane-terminated side-chains and fluorine substitution promoted the intermolecular packing,showing well resolved lamellar scatterings up to (300) for this series of polymers in the grazing incidence wide angle X-ray scattering measurements.The PPsiDTBT,PPsiDTFBT and PPsiDT2FBT devices showed a power conversion efficiency of 3.16％,4.40％ and 5.65％,respectively,by blending with PC71BM.Langevin-type bimolecular charge recombination was similar for three polymeric solar cells.The main loss in the photocurrent generation for PPsiDTBT:PC71BM was interpreted to originate from the trap assisted charge recombination by measuring light-intensity dependent short-circuit current density (Jsc) and open-circuit voltage (Voc).Our results provide a new insight into the rational selection of solubilizing substituents for optimizing crystalline interchain packing with appropriate miscibility with PC71BM for further optimizing polymer solar cells.

Effects of Rational-Emotive Therapy, Rational Role Reversal, and Rational-Emotive Imagery on the Emotional Adjustment of Community Mental Health Center Patients.

Science.gov (United States)

Lipsky, Marc J.; And Others

1980-01-01

Results showed that rational-emotive therapy (RET), with the addition of rational role reversal, produced significantly better results than did relaxation training and support or no contact. This was the first study to demonstrate the efficacy of RET with multisymptomatic applicants to a community mental health center. (Author/BEF)

Argumentation, rationality, and psychology of reasoning

Directory of Open Access Journals (Sweden)

David Godden

2015-05-01

Full Text Available This paper explicates an account of argumentative rationality by articulating the common, basic idea of its nature, and then identifying a collection of assumptions inherent in it. Argumentative rationality is then contrasted with dual-process theories of reasoning and rationality prevalent in the psychology of reasoning. It is argued that argumentative rationality properly corresponds only with system-2 reasoning in dual-process theories. This result challenges the prescriptive force of argumentative norms derives if they derive at all from their descriptive accuracy of our cognitive capacities. In response, I propose an activity-based account of reasoning which retains the assumptions of argumentative rationality while recontextualizing the relationship between reasoning as a justificatory activity and the psychological states and processes underlying that activity.

Multifunctional Polymer/Inorganic Nanocomposites

National Research Council Canada - National Science Library

Manias, E

2003-01-01

... in multifunctional nanocomposite materials. Understanding the structure/property relations in polymer/clay nanocomposites is of great importance in designing materials with desired sets of properties...

Rational Thinking in School-Based Practice

Science.gov (United States)

Clark, Mary Kristen; Flynn, Perry

2011-01-01

Purpose: We reflect on Alan Kamhi's (2011) prologue on balancing certainty and uncertainty as it pertains to school-based practice. Method: In schools, rational thinking depends on effective team processes, much like professional learning communities. We consider the conditions that are required for rational thinking and how rational team dialogue…

Milk Production, Physiological Condition and Performance of Etawa Crossbreed Goats Feed by Ration Supplemented with Mangosteen Peel Flour

Science.gov (United States)

Dzarnisa; Rachmadi, D.; Azhar, A.; Fakhrur Riza, R.; Hidayati, A.

2018-02-01

Study on the effect of the addition of mangosteen (Garcinia mangostana L.) peel flour on physiological condition and performance of Etawa crossbreed goats was done. This was to grant the use of mangosteen peel flour that rich of antioxidants and has variety good benefits for health as feed additive for cattle. This study used a Complete Randomized Block Design consisting of 4 treatment groups and 4 replications each. Subjects were 16 female Etawa crossbreed goats randomly designed into treatments group based on lactation periods. Subjects were feed with traditional rations (control, A), traditional rations and 2.5% mangosteen peel flour (B), tradition rations and 5% mangosteen peel flour (C), and traditional rations and 7,5 % mangosteen peel flour (D). Data on performance (milk production) and physiological condition (respiratory frequency, rectal temperature, and heart rate) obtained were analyzed using analysis of variance (ANOVA). The results showed that the addition of mangosteen peel flour as food additive in the rations resulted in variations in the milk production, physiological condition (rectal temperature, heart rate and respiration frequency) and performances (daily weigh gain, food consumption, ration conversion and breast volume) of Etawa crossbreed goats, but significant effect was only observed in the respiration frequency. The addition of 2.5% mangosteen peel flour in the ration caused the best, expected effects on milk production physiological condition and performance of Etawa crossbreed goats.

Design, preparation, and application of ordered porous polymer materials

International Nuclear Information System (INIS)

Liu, Qingquan; Tang, Zhe; Ou, Baoli; Liu, Lihua; Zhou, Zhihua; Shen, Shaohua; Duan, Yinxiang

2014-01-01

Ordered porous polymer (OPP) materials have extensively application prospects in the field of separation and purification, biomembrane, solid supports for sensors catalysts, scaffolds for tissue engineering, photonic band gap materials owing to ordered pore arrays, uniform and tunable pore size, high specific surface area, great adsorption capacity, and light weight. The present paper reviewed the preparation techniques of OPP materials like breath figures, hard template, and soft template. Finally, the applications of OPP materials in the field of separation, sensors, and biomedicine are introduced, respectively. - Highlights: • Breath figures involve polymer casting under moist ambience. • Hard template employs monodisperse colloidal spheres as a template. • Soft template utilizes the etched block in copolymers as template

Ventilation, good indoor air quality and rational use of energy

DEFF Research Database (Denmark)

Clausen, Geo; Fernandes, E. D. O.; DeGids, W.

2003-01-01

The aim of this report is to provide information and advice to policy and decission makers, researchers, architects, designers, and manufacturers on strategies for achieving a good balance between good indoor air quality (IAQ) and the rational use of Energy in buildings, available guidelines...

Updated Army Cook Staffing Model to Reflect Workloads Generated by Current Field Feeding Operations, Group Rations, and Kitchens

National Research Council Canada - National Science Library

Kirejczyk, Harry J

2006-01-01

...: the Unitized Group Ration-A (UGR-A) and the Unitized Group Ration-Heat/Serve (UGR-H/S). These fieldings were designed to increase the frequency and quality of group hot meals and reduce the cook workloads generated by field feeding operations...

Rationality in Machiavelli and in Kant

Directory of Open Access Journals (Sweden)

Vadim Chaly

2016-11-01

Full Text Available The paper contains interpretation and comparative analysis of Machiavelli’s and Kant’s conceptions on rationality as two prime examples of “realist” and “idealist” modes of agency. Kantian model of rationality is viewed as an augmentation of the Machiavellian one, not an opposition to it. To elaborate the point, Robert Aumann’s model of act-rationality and rulerationality is applied to the two philosophical models. Kantian practical reason is interpreted as an addition to Aumann’s instrumental rationality, providing rules for rules, or “rule-rule-rationality”.

Towards a Rational Kingdom in Africa: Knowledge, Critical Rationality and Development in a Twenty-First Century African Cultural Context

Directory of Open Access Journals (Sweden)

Lawrence Ogbo Ugwuanyi

2018-03-01

Full Text Available This paper seeks to locate the kind of knowledge that is relevant for African development in the twenty-first century African cultural context and to propose the paradigm for achieving such knowledge. To do this, it advances the view that the concept of twenty-first century in an African context must be located with the colonial and post-colonial challenges of the African world and applied to serve the African demand. Anchored on this position, the paper outlines and critiques the wrong assumption on which modern state project was anchored in post-colonial Africa and its development dividend to suggest that this is an outcome of a wrong knowledge design that is foundational to the state project and which the project did not address. It proposes a shift in the knowledge paradigm in Africa and suggests critical self-consciousness as a more desirable knowledge design for Africa. It applies the term ‘rational kingdom’ (defined as a community of reason marked by critical conceptual self-awareness driven by innovation and constructivism to suggest this paradigm. ‘Innovation’ is meant as the application of reason with an enlarged capacity to anticipate and address problems with fresh options and ‘constructivism’ is meant as the disposition to sustain innovation by advancing an alternative but more reliable worldview that can meet the exigencies of modernity in an African cultural context. The paper then proceeds to outline the nature of the rational kingdom and its anticipated gains and outcomes. It applies the method of inductive reasoning to advance its position. To do this it invokes selected but crucial areas of African life to locate how the developmental demands of these aspects of life suggest a critical turn in African rationality.

Effects of polymer-nanoparticle interactions on the viscosity of unentangled polymers under extreme nanoconfinement during capillary rise infiltration.

Science.gov (United States)

Hor, Jyo Lyn; Wang, Haonan; Fakhraai, Zahra; Lee, Daeyeon

2018-03-28

We explore the effect of confinement and polymer-nanoparticle interactions on the viscosity of unentangled polymers undergoing capillary rise infiltration (CaRI) in dense packings of nanoparticles. In CaRI, a polymer is thermally induced to wick into the dense packings of nanoparticles, leading to the formation of polymer-infiltrated nanoparticle films, a new class of thin film nanocomposites with extremely high concentrations of nanoparticles. To understand the effect of this extreme nanoconfinement, as well as polymer-nanoparticle interactions on the polymer viscosity in CaRI films, we use two polymers that are known to have very different interactions with SiO2 nanoparticles. Using in situ spectroscopic ellipsometry, we monitor the polymer infiltration process, from which we infer the polymer viscosity based on the Lucas-Washburn model. Our results suggest that physical confinement increases the viscosity by approximately two orders of magnitude. Furthermore, confinement also increases the glass transition temperature of both polymers. Thus, under extreme nanoconfinement, the physical confinement has a more significant impact than the polymer-nanoparticle interactions on the viscosity of unentangled polymers, measured through infiltration dynamics, as well as the glass transition temperature. These findings will provide fundamental frameworks for designing processes to enable the fabrication of CaRI nanocomposite films with a wide range of nanoparticles and polymers.

Using artificial intelligence methods to design new conducting polymers

Directory of Open Access Journals (Sweden)

Ronaldo Giro

2003-12-01

Full Text Available In the last years the possibility of creating new conducting polymers exploring the concept of copolymerization (different structural monomeric units has attracted much attention from experimental and theoretical points of view. Due to the rich carbon reactivity an almost infinite number of new structures is possible and the procedure of trial and error has been the rule. In this work we have used a methodology able of generating new structures with pre-specified properties. It combines the use of negative factor counting (NFC technique with artificial intelligence methods (genetic algorithms - GAs. We present the results for a case study for poly(phenylenesulfide phenyleneamine (PPSA, a copolymer formed by combination of homopolymers: polyaniline (PANI and polyphenylenesulfide (PPS. The methodology was successfully applied to the problem of obtaining binary up to quinternary disordered polymeric alloys with a pre-specific gap value or exhibiting metallic properties. It is completely general and can be in principle adapted to the design of new classes of materials with pre-specified properties.

Effective Entrepreneurial Choice: The Role of Rationality and Non-Rationality in Three Entrepreneurs Success Stories

OpenAIRE

Chong, Anne Michele, Siang Yoon

2007-01-01

Good entrepreneurship is important for economic growth and productivity in any modern economy. The purpose of this dissertation is to research how good entrepreneurial decisions are made. In theory, optimal or rational decision making means choosing the best alternative in response to the problem. However, in reality, people do not act rationally because they often cannot make rational choices. The reason is that people do not have enough brain power, time or resources to process the compl...

Applications of Polymers as Pharmaceutical Excipients in Solid Oral Dosage Forms.

Science.gov (United States)

Debotton, Nir; Dahan, Arik

2017-01-01

Over the last few decades, polymers have been extensively used as pharmaceutical excipients in drug delivery systems. Pharmaceutical polymers evolved from being simply used as gelatin shells comprising capsule to offering great formulation advantages including enabling controlled/slow release and specific targeting of drugs to the site(s) of action (the "magic bullets" concept), hence hold a significant clinical promise. Oral administration of solid dosage forms (e.g., tablets and capsules) is the most common and convenient route of drug administration. When formulating challenging molecules into solid oral dosage forms, polymeric pharmaceutical excipients permit masking undesired physicochemical properties of drugs and consequently, altering their pharmacokinetic profiles to improve the therapeutic effect. As a result, the number of synthetic and natural polymers available commercially as pharmaceutical excipients has increased dramatically, offering potential solutions to various difficulties. For instance, the different polymers may allow increased solubility, swellability, viscosity, biodegradability, advanced coatings, pH dependency, mucodhesion, and inhibition of crystallization. The aim of this article is to provide a wide angle prospect of the different uses of pharmaceutical polymers in solid oral dosage forms. The various types of polymeric excipients are presented, and their distinctive role in oral drug delivery is emphasized. The comprehensive know-how provided in this article may allow scientists to use these polymeric excipients rationally, to fully exploit their different features and potential influence on drug delivery, with the overall aim of making better drug products. © 2016 Wiley Periodicals, Inc.

Rationalization and Design of Enhanced Photoinduced Cycloreversion in Photochromic Dimethyldihydropyrenes by Theoretical Calculations.

Science.gov (United States)

Boggio-Pasqua, Martial; Garavelli, Marco

2015-06-11

This study presents a computational investigation of the initial step of the dimethyldihydropyrene (DHP) to cyclophanediene (CPD) photoinduced ring-opening reaction using time-dependent density functional theory (TD-DFT). In particular, the photochemical path corresponding to the formation of the CPD precursor (CPD*) on the zwitterionic state is scrutinized. The TD-DFT approach was first validated on the parent compound against accurate ab initio calculations. It confirms that CPD* formation is efficiently quenched in this system by an easily accessible S2/S1 conical intersection located in the vicinity of the CPD* minimum and leading to a locally excited state minimum responsible for DHP luminescence. Increased ring-opening quantum yields were observed in benzo[e]-fused-DHP (DHP-1), isobutenyl-DHP (DHP-2), and naphthoyl-DHP (DHP-3). The calculations show that CPD* formation is much more favorable in these systems, either due to an inversion of electronic states in DHP-1, suppressing the formation of the locally excited state, or due to efficient stabilization of CPD* on the S1 potential energy surface in DHP-2 and DHP-3. Both effects can be combined in a rationally designed benzo[e]-fused-naphthoyl-DHP (DHP-4) for which we anticipate an unprecedented efficiency.

Induced helical backbone conformations of self-organizable dendronized polymers.

Science.gov (United States)

Rudick, Jonathan G; Percec, Virgil

2008-12-01

information to rationalize function as retrostructural analysis. Retrostructural analysis validates our hypothesis that the self-assembling dendrons induce a helical backbone conformation in cylindrical self-organizable dendronized polymers. This helical conformation mediates unprecedented functions. Self-organizable dendronized polymers have emerged as powerful building blocks for nanoscience by virtue of their dimensions and ability to self-organize. Discrete cylindrical and spherical structures with well-defined dimensions can be visualized and manipulated individually. More importantly, they provide a robust framework for elucidating functions available only at the nanoscale. This Account will highlight structures and functions generated from self-organizable dendronized polymers that enable integration of the nanoworld with its macroscopic universe. Emphasis is placed on those structures and functions derived from the induced helical backbone conformation of cylindrical self-organizable dendronized polymers.

Changing fields of rationality - a policy for change?

Energy Technology Data Exchange (ETDEWEB)

Strumse, Einar; Westskog, Hege; Winther, Tanja

2010-07-01

Work objective: To analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. Methodology: In this paper we develop a conceptual model for understanding individuals' energy consumption. We synthesize insights from anthropology, social psychology and economics grasping perspectives from behaviour to practice and from the Bourdieu's fields to rationality thinking in economics. We use this insight to analyze strategies for change. Abstract: In this paper we analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. The model focuses on four main categories for understanding individual consumption: a. Material constraints b. Values and identity c. Norms d. Ability These are the main influencing factors of the individual's consumption level, but in interaction with the corresponding group and the societal levels for the same factors. The model can be illustrated. One combination of factors on all levels constitutes a field of rationality. We claim that an important strategy for changing energy consumption towards sustainability is changing the field of rationality of the individual. Changing of rationality fields would from our point of view initiate reflection which is an important condition for changed behavior. One example of changing of fields is information measures that relates energy consumption to the 'citizen' field rather than the 'consumer' field. Hence, according to our conceptual framework - how policy should be framed (information measures for instance ) would be an important knowledge area for design of effective policy measures. (Author)

AIE Polymers: Synthesis, Properties, and Biological Applications.

Science.gov (United States)

Zhan, Ruoyu; Pan, Yutong; Manghnani, Purnima Naresh; Liu, Bin

2017-05-01

Aggregation-caused quenching (ACQ) is a general phenomenon that is faced by traditional fluorescent polymers. Aggregation-induced emission (AIE) is exactly opposite to ACQ. AIE molecules are almost nonemissive in their molecularly dissolved state, but they can be induced to show high fluorescence in the aggregated or solid state. Incorporation of AIE phenomenon into polymer design has yielded various polymers with AIE characteristics. In this review, the recent progress of AIE polymers for biological applications is summarized. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discrete Choice and Rational Inattention

DEFF Research Database (Denmark)

Fosgerau, Mogens; Melo, Emerson; de Palma, André

2017-01-01

This paper establishes a general equivalence between discrete choice and rational inattention models. Matejka and McKay (2015, AER) showed that when information costs are modelled using the Shannon entropy, the result- ing choice probabilities in the rational inattention model take the multinomial...... logit form. We show that when information costs are modelled using a class of generalized entropies, then the choice probabilities in any rational inattention model are observationally equivalent to some additive random utility discrete choice model and vice versa. This equivalence arises from convex...

Rational top and its classical r-matrix

International Nuclear Information System (INIS)

Aminov, G; Arthamonov, S; Smirnov, A; Zotov, A

2014-01-01

We construct a rational integrable system (the rational top) on a co-adjoint orbit of SL N Lie group. It is described by the Lax operator with spectral parameter and classical non-dynamical skew-symmetric r-matrix. In the case of the orbit of minimal dimension the model is gauge equivalent to the rational Calogero–Moser (CM) system. To obtain the results we represent the Lax operator of the CM model in two different factorized forms—without spectral parameter (related to the spinless case) and another one with the spectral parameter. The latter gives rise to the rational top while the first one is related to generalized Cremmer–Gervais r-matrices. The gauge transformation relating the rational top and CM model provides the classical rational version of the IRF-Vertex correspondence. From the geometrical point of view it describes the modification of SL(N,C)-bundles over degenerated elliptic curve. In view of the Symplectic Hecke Correspondence the rational top is related to the rational spin CM model. Possible applications and generalizations of the suggested construction are discussed. In particular, the obtained r-matrix defines a class of KZB equations. (paper)

Fiber sources for complete calf starter rations.

Science.gov (United States)

Murdock, F R; Wallenius, R W

1980-11-01

Complete calf starter rations containing either 1) alfalfa hay, 2) cottonseed hulls, or 3) alfalfa-beet pulp as sources of fiber were fed to Holstein heifer calves at two locations on a limited milk program from 3 days to 12 wk of age. Rations were isonitrogenous and similar in content of crude fiber and acid detergent fiber. Although growth and development were normal on all rations, calves fed the cottonseed hull ration consumed more starter and gained more body weight than calves fed the other sources of fiber. The similarity of feed efficiencies, rumen pH, and molar ratios of volatile fatty acids between rations indicated no appreciable differences in rumen development or function. The growth response of calves fed the cottonseed hull ration appeared to be a result of better ration acceptability for which no reason was evident. Calves raised at Puyallup gained more body weight than calves at Pullman, and these gains were made more efficiently. These location effects may be related to seasonal differences and greater demands for production of body heat. Although the incidence of scours was less for calves fed alfalfa hay starter, the incidence and severity of bloat were higher for that ration.

New Incremental Actuators based on Electro-active Polymer: Conceptual, Control, and Driver Design Considerations. 

OpenAIRE

Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe; Andersen, Michael A. E.; Sarban, Rahimullah

2016-01-01

This paper presents an overview of the widely usedconventional linear actuator technologies and existing electroactivepolymer based linear and rotary actuators. It also providesthe conceptual, control and driver design considerations for anew dielectric electro-active polymer (DEAP) based incrementalactuator. The DEAP incremental actuator consists of threeindependent DEAP actuators with a unique cylindrical designthat potentially simplifies mass production and scalabilitycompared to existing ...

Multiscale design and life-cycle based sustainability assessment of polymer nanocomposite coatings

Science.gov (United States)

Uttarwar, Rohan G.

In recent years, nanocoatings with exceptionally improved and new performance properties have found numerous applications in the automotive, aerospace, ship-making, chemical, electronics, steel, construction, and many other industries. Especially the formulations providing multiple functionalities to cured paint films are believed to dominate the coatings market in the near future. It has shifted the focus of research towards building sustainable coating recipes which can deliver multiple functionalities through applied films. The challenge to this exciting area of research arrives from the insufficient knowledge about structure-property correlations of nanocoating materials and their design complexity. Experimental efforts have been successful in developing certain types of nanopaints exhibiting improved properties. However, multifunctional nanopaint design optimality is extremely difficult to address if not impossible solely through experiments. In addition to this, the environmental implications and societal risks associated with this growing field of nanotechnology raise several questions related to its sustainable development. This research focuses on the study of a multiscale sustainable nanocoating design which can have the application from novel function envisioning and idea refinement point of view, to knowledge discovery and design solution derivation, and further to performance testing in industrial applications. The nanocoating design is studied using computational simulations of nano- to macro- scale models and sustainability assessment study over the life-cycle. Computational simulations aim at integrating top-down, goals/means, inductive systems engineering and bottom-up, cause and effect, deductive systems engineering approaches for material development. The in-silico paint resin system is a water-dispersible acrylic polymer with hydrophilic nanoparticles incorporated into it. The nano-scale atomistic and micro-scale coarse-grained (CG) level

Multifunctional Nanotube Polymer Nanocomposites for Aerospace Applications: Adhesion between SWCNT and Polymer Matrix

Science.gov (United States)

Park, Cheol; Wise, Kristopher E.; Kang, Jin Ho; Kim, Jae-Woo; Sauti, Godfrey; Lowther, Sharon E.; Lillehei, Peter T.; Smith, Michael W.; Siochi, Emilie J.; Harrison, Joycelyn S.;

Lessons from Learning to Have Rational Expectations

OpenAIRE

Lindh, Thomas

1989-01-01

This paper reviews a growing literature investigating how economic agents may learn rational expectations. Fully rational learning requires implausible initial information assumptions, therefore some form of bounded rationality has come into focus. Such learning models often converge to rational expectations equilibria within certain bounds. Convergence analysis has been much simplified by methods from adaptive control theory. Learning stability as a correspondence principle show some promise...

Recoding aminoacyl-tRNA synthetases for synthetic biology by rational protein-RNA engineering.

Science.gov (United States)

Hadd, Andrew; Perona, John J

2014-12-19

We have taken a rational approach to redesigning the amino acid binding and aminoacyl-tRNA pairing specificities of bacterial glutaminyl-tRNA synthetase. The four-stage engineering incorporates generalizable design principles and improves the pairing efficiency of noncognate glutamate with tRNA(Gln) by over 10(5)-fold compared to the wild-type enzyme. Better optimized designs of the protein-RNA complex include substantial reengineering of the globular core region of the tRNA, demonstrating a role for specific tRNA nucleotides in specifying the identity of the genetically encoded amino acid. Principles emerging from this engineering effort open new prospects for combining rational and genetic selection approaches to design novel aminoacyl-tRNA synthetases that ligate noncanonical amino acids onto tRNAs. This will facilitate reconstruction of the cellular translation apparatus for applications in synthetic biology.

Injection molded polymer optics in the 21st Century

Science.gov (United States)

Beich, William S.

2005-08-01

Precision polymer optics, manufactured by injection molding techniques, has been a key enabling technology for several decades now. The technology, which can be thought of as a subset of the wider field of precision optics manufacturing, was pioneered in the United States by companies such as Eastman Kodak, US Precision Lens, and Polaroid. In addition to suppliers in the U.S. there are several companies worldwide that design and manufacture precision polymer optics, for example Philips High Tech Plastics in Europe and Fujinon in Japan. Designers who are considering using polymer optics need a fundamental understanding of exactly how the optics are created. This paper will survey the technology and processes that are employed in the successful implementation of a polymer optic solution from a manufacturer's perspective. Special emphasis will be paid to the unique relationship between the molds and the optics that they produce. We will discuss the key elements of production: molding resins, molds and molding equipment, and metrology. Finally we will offer a case study to illustrate just how the optics designer carries a design concept through to production. The underlying theme throughout the discussion of polymer optics is the need for the design team to work closely with an experienced polymer optics manufacturer with a solid track record of success in molded optics. As will be seen shortly, the complex interaction between thermoplastics, molds, and molding machines dictates the need for working closely with a supplier who has the critical knowledge needed to manage all aspects of the program.

Starlings uphold principles of economic rationality for delay and probability of reward.

Science.gov (United States)

Monteiro, Tiago; Vasconcelos, Marco; Kacelnik, Alex

2013-04-07

Rationality principles are the bedrock of normative theories of decision-making in biology and microeconomics, but whereas in microeconomics, consistent choice underlies the notion of utility; in biology, the assumption of consistent selective pressures justifies modelling decision mechanisms as if they were designed to maximize fitness. In either case, violations of consistency contradict expectations and attract theoretical interest. Reported violations of rationality in non-humans include intransitivity (i.e. circular preferences) and lack of independence of irrelevant alternatives (changes in relative preference between options when embedded in different choice sets), but the extent to which these observations truly represent breaches of rationality is debatable. We tested both principles with starlings (Sturnus vulgaris), training subjects either with five options differing in food delay (exp. 1) or with six options differing in reward probability (exp. 2), before letting them choose repeatedly one option out of several binary and trinary sets of options. The starlings conformed to economic rationality on both tests, showing strong stochastic transitivity and no violation of the independence principle. These results endorse the rational choice and optimality approaches used in behavioural ecology, and highlight the need for functional and mechanistic enquiring when apparent violations of such principles are observed.

Novel silicone-based polymer containing active methylene designed for the removal of indoor formaldehyde

Energy Technology Data Exchange (ETDEWEB)

Niu, Song, E-mail: niusong84@163.com; Yan, Hongxia, E-mail: hongxiayan@nwpu.edu.cn

2015-04-28

Highlights: • A novel silicone-based polymer with active methylene was explored. • Surface tension of liquid paints could be lowered using the polymer. • The polymer was easy to migrate toward the air-coating interface. • Free HCHO could effectively be removed using the polymer. • A lights on HCHO reduction without complicated preparation procedure was shielded. - Abstract: Indoor air pollution is caused inevitably due to complicated home decoration, in which formaldehyde is one of the most typical pollutants. It will be a convenient, economical and effective strategy to remove indoor formaldehyde if imparting a feature of formaldehyde removal to decorative coatings. We have successfully explored a novel silicone-based polymer containing active methylene used as a formaldehyde absorbent in coatings via a straightforward transesterification process using inexpensive and easily available chemicals. The polymer has been characterized by {sup 13}C NMR, FTIR, GC and GPC. Formaldehyde removal capacity of the coating films containing different contents of the polymer has been investigated. The results indicated that coatings incorporating 4 wt% of the polymer could make the coating films exhibit significant improvement on formaldehyde removal including purificatory performance (>85%) and durability of purificatory effect (>60%), compared to those consisting of absorbents without any silicon, and improve yellowing resistance performance, while other properties, such as gloss, adhesion, pencil hardness, flexibility and impact resistance, were kept almost unaffected. The chemical absorption process of the silicone-based polymer filled in interior decorative coatings is demonstrated as a promising technology to purify indoor formaldehyde and thus can reduce the harm to individuals.

Strategy selection as rational metareasoning.

Science.gov (United States)

Lieder, Falk; Griffiths, Thomas L

2017-11-01

Many contemporary accounts of human reasoning assume that the mind is equipped with multiple heuristics that could be deployed to perform a given task. This raises the question of how the mind determines when to use which heuristic. To answer this question, we developed a rational model of strategy selection, based on the theory of rational metareasoning developed in the artificial intelligence literature. According to our model people learn to efficiently choose the strategy with the best cost-benefit tradeoff by learning a predictive model of each strategy's performance. We found that our model can provide a unifying explanation for classic findings from domains ranging from decision-making to arithmetic by capturing the variability of people's strategy choices, their dependence on task and context, and their development over time. Systematic model comparisons supported our theory, and 4 new experiments confirmed its distinctive predictions. Our findings suggest that people gradually learn to make increasingly more rational use of fallible heuristics. This perspective reconciles the 2 poles of the debate about human rationality by integrating heuristics and biases with learning and rationality. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Fabrication and characterization of shape memory polymers at small-scales

Science.gov (United States)

Wornyo, Edem

The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory polymers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) Design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) Utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) Utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) Study spin coating conditions on thin film quality with designed experiments. (iv) Apply neural networks and genetic algorithms to optimize these systems.

Asymmetric diketopyrrolopyrrole conjugated polymers for field-effect transistors and polymer solar cells processed from a non-chlorinated solvent

NARCIS (Netherlands)

Ji, Y.; Xiao, C.; Wang, Q.; Zhang, J.; Li, C.; Wu, Y.; Wei, Z.; Zhan, X.; Hu, W.; Wang, Z.; Janssen, R.A.J.; Li, W.W.

2016-01-01

Newly designed asymmetric diketopyrrolopyrrole conjugated polymers with two different aromatic substituents possess a hole mobility of 12.5 cm2 V−1 s−1 in field-effect transistors and a power conversion efficiency of 6.5% in polymer solar cells, when solution processed from a nonchlorinated

Should informed consent be based on rational beliefs?

Science.gov (United States)

Savulescu, J; Momeyer, R W

1997-10-01

Our aim is to expand the regulative ideal governing consent. We argue that consent should not only be informed but also based on rational beliefs. We argue that holding true beliefs promotes autonomy. Information is important insofar as it helps a person to hold the relevant true beliefs. But in order to hold the relevant true beliefs, competent people must also think rationally. Insofar as information is important, rational deliberation is important. Just as physicians should aim to provide relevant information regarding the medical procedures prior to patients consenting to have those procedures, they should also assist patients to think more rationally. We distinguish between rational choice/action and rational belief. While autonomous choice need not necessarily be rational, it should be based on rational belief. The implication for the doctrine of informed consent and the practice of medicine is that, if physicians are to respect patient autonomy and help patients to choose and act more rationally, not only must they provide information, but they should care more about the theoretical rationality of their patients. They should not abandon their patients to irrationality. They should help their patients to deliberate more effectively and to care more about thinking rationally. We illustrate these arguments in the context of Jehovah's Witnesses refusing life-saving blood transfusions. Insofar as Jehovah's Witnesses should be informed of the consequences of their actions, they should also deliberate rationally about these consequences.

Evaluation and rational design of guide RNAs for efficient CRISPR/Cas9-mediated mutagenesis in Ciona.

Science.gov (United States)

Gandhi, Shashank; Haeussler, Maximilian; Razy-Krajka, Florian; Christiaen, Lionel; Stolfi, Alberto

2017-05-01

The CRISPR/Cas9 system has emerged as an important tool for various genome engineering applications. A current obstacle to high throughput applications of CRISPR/Cas9 is the imprecise prediction of highly active single guide RNAs (sgRNAs). We previously implemented the CRISPR/Cas9 system to induce tissue-specific mutations in the tunicate Ciona. In the present study, we designed and tested 83 single guide RNA (sgRNA) vectors targeting 23 genes expressed in the cardiopharyngeal progenitors and surrounding tissues of Ciona embryo. Using high-throughput sequencing of mutagenized alleles, we identified guide sequences that correlate with sgRNA mutagenesis activity and used this information for the rational design of all possible sgRNAs targeting the Ciona transcriptome. We also describe a one-step cloning-free protocol for the assembly of sgRNA expression cassettes. These cassettes can be directly electroporated as unpurified PCR products into Ciona embryos for sgRNA expression in vivo, resulting in high frequency of CRISPR/Cas9-mediated mutagenesis in somatic cells of electroporated embryos. We found a strong correlation between the frequency of an Ebf loss-of-function phenotype and the mutagenesis efficacies of individual Ebf-targeting sgRNAs tested using this method. We anticipate that our approach can be scaled up to systematically design and deliver highly efficient sgRNAs for the tissue-specific investigation of gene functions in Ciona. Copyright © 2017 Elsevier Inc. All rights reserved.