[Development of selective determination methods for quinones with fluorescence and chemiluminescence detection and their application to environmental and biological samples].

PubMed

Kishikawa, Naoya

2010-10-01

Quinones are compounds that have various characteristics such as a biological electron transporter, an industrial product and a harmful environmental pollutant. Therefore, an effective determination method for quinones is required in many fields. This review describes the development of sensitive and selective determination methods for quinones based on some detection principles and their application to analyses in environmental, pharmaceutical and biological samples. Firstly, a fluorescence method was developed based on fluorogenic derivatization of quinones and applied to environmental analysis. Secondly, a luminol chemiluminescence method was developed based on generation of reactive oxygen species through the redox cycle of quinone and applied to pharmaceutical analysis. Thirdly, a photo-induced chemiluminescence method was developed based on formation of reactive oxygen species and fluorophore or chemiluminescence enhancer by the photoreaction of quinones and applied to biological and environmental analyses.

Swarm robotics and minimalism

NASA Astrophysics Data System (ADS)

Sharkey, Amanda J. C.

2007-09-01

Swarm Robotics (SR) is closely related to Swarm Intelligence, and both were initially inspired by studies of social insects. Their guiding principles are based on their biological inspiration and take the form of an emphasis on decentralized local control and communication. Earlier studies went a step further in emphasizing the use of simple reactive robots that only communicate indirectly through the environment. More recently SR studies have moved beyond these constraints to explore the use of non-reactive robots that communicate directly, and that can learn and represent their environment. There is no clear agreement in the literature about how far such extensions of the original principles could go. Should there be any limitations on the individual abilities of the robots used in SR studies? Should knowledge of the capabilities of social insects lead to constraints on the capabilities of individual robots in SR studies? There is a lack of explicit discussion of such questions, and researchers have adopted a variety of constraints for a variety of reasons. A simple taxonomy of swarm robotics is presented here with the aim of addressing and clarifying these questions. The taxonomy distinguishes subareas of SR based on the emphases and justifications for minimalism and individual simplicity.

Structure, reactivity, and electronic properties of V-doped Co clusters

NASA Astrophysics Data System (ADS)

Datta, Soumendu; Kabir, Mukul; Saha-Dasgupta, Tanusri; Mookerjee, Abhijit

2009-08-01

Structures and physicochemical properties of V-doped Co13 clusters have been studied in detail using density-functional-theory-based first-principles method. We have found anomalous variation in stability of the doped clusters with increasing V concentration, which has been nicely demonstrated in terms of energetics and electronic properties of the clusters. Our study explains the nonmonotonic variation in reactivity of Co13-mVm clusters toward H2 molecules as reported experimentally [Nonose , J. Phys. Chem. 94, 2744 (1990)]. Moreover, it provides useful insight into the cluster geometry and chemically active sites on the cluster surface, which can help to design better catalytic processes.

Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

PubMed

Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

2016-01-21

The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

A Model to Couple Flow, Thermal and Reactive Chemical Transport, and Geo-mechanics in Variably Saturated Media

NASA Astrophysics Data System (ADS)

Yeh, G. T.; Tsai, C. H.

2015-12-01

This paper presents the development of a THMC (thermal-hydrology-mechanics-chemistry) process model in variably saturated media. The governing equations for variably saturated flow and reactive chemical transport are obtained based on the mass conservation principle of species transport supplemented with Darcy's law, constraint of species concentration, equation of states, and constitutive law of K-S-P (Conductivity-Degree of Saturation-Capillary Pressure). The thermal transport equation is obtained based on the conservation of energy. The geo-mechanic displacement is obtained based on the assumption of equilibrium. Conventionally, these equations have been implicitly coupled via the calculations of secondary variables based on primary variables. The mechanisms of coupling have not been obvious. In this paper, governing equations are explicitly coupled for all primary variables. The coupling is accomplished via the storage coefficients, transporting velocities, and conduction-dispersion-diffusion coefficient tensor; one set each for every primary variable. With this new system of equations, the coupling mechanisms become clear. Physical interpretations of every term in the coupled equations will be discussed. Examples will be employed to demonstrate the intuition and superiority of these explicit coupling approaches. Keywords: Variably Saturated Flow, Thermal Transport, Geo-mechanics, Reactive Transport.

[Application of photodynamic therapy in dentistry – literature review].

PubMed

Oruba, Zuzanna; Chomyszyn-Gajewska, Maria

Photodynamic therapy (PDT) is based on the principle that the target cells are destroyed by means of toxic reactive oxygen species generated upon the interaction of a photosensitizer, light and oxygen. This method is nowadays widely applied in various branches of medicine, mainly in oncology and dermatology. It is also applied in dentistry in the treatment of oral potentially malignant disorders (like lichen planus or leukoplakia) and infectious conditions (periodontitis, herpetic cheilitis, root canal disinfection). The application of the photodynamic therapy in the abovementioned indications is worth attention, as the method is noninvasive, painless, and the results of the published studies seem promising. The present article aims at presenting the principle of the photodynamic therapy and, based on the literature, the possibilities and results of its application in dentistry.

Surface Reactivity of Li2MnO3: First-Principles and Experimental Study.

PubMed

Quesne-Turin, Ambroise; Flahaut, Delphine; Croguennec, Laurence; Vallverdu, Germain; Allouche, Joachim; Charles-Blin, Youn; Chotard, Jean-Noël; Ménétrier, Michel; Baraille, Isabelle

2017-12-20

This article deals with the surface reactivity of (001)-oriented Li 2 MnO 3 crystals investigated from a multitechnique approach combining material synthesis, X-ray photoemission spectroscopy (XPS), scanning electron microscopy, Auger electron spectroscopy, and first-principles calculations. Li 2 MnO 3 is considered as a model compound suitable to go further in the understanding of the role of tetravalent manganese atoms in the surface reactivity of layered lithium oxides. The knowledge of the surface properties of such materials is essential to understand the mechanisms involved in parasitic phenomena responsible for early aging or poor storage performances of lithium-ion batteries. The surface reactivity was probed through the adsorption of SO 2 gas molecules on large Li 2 MnO 3 crystals to be able to focus the XPS beam on the top of the (001) surface. A chemical mapping and XPS characterization of the material before and after SO 2 adsorption show in particular that the adsorption is homogeneous at the micro- and nanoscale and involves Mn reduction, whereas first-principles calculations on a slab model of the surface allow us to conclude that the most energetically favorable species formed is a sulfate with charge transfer implying reduction of Mn.

Metascalable molecular dynamics simulation of nano-mechano-chemistry

NASA Astrophysics Data System (ADS)

Shimojo, F.; Kalia, R. K.; Nakano, A.; Nomura, K.; Vashishta, P.

2008-07-01

We have developed a metascalable (or 'design once, scale on new architectures') parallel application-development framework for first-principles based simulations of nano-mechano-chemical processes on emerging petaflops architectures based on spatiotemporal data locality principles. The framework consists of (1) an embedded divide-and-conquer (EDC) algorithmic framework based on spatial locality to design linear-scaling algorithms, (2) a space-time-ensemble parallel (STEP) approach based on temporal locality to predict long-time dynamics, and (3) a tunable hierarchical cellular decomposition (HCD) parallelization framework to map these scalable algorithms onto hardware. The EDC-STEP-HCD framework exposes and expresses maximal concurrency and data locality, thereby achieving parallel efficiency as high as 0.99 for 1.59-billion-atom reactive force field molecular dynamics (MD) and 17.7-million-atom (1.56 trillion electronic degrees of freedom) quantum mechanical (QM) MD in the framework of the density functional theory (DFT) on adaptive multigrids, in addition to 201-billion-atom nonreactive MD, on 196 608 IBM BlueGene/L processors. We have also used the framework for automated execution of adaptive hybrid DFT/MD simulation on a grid of six supercomputers in the US and Japan, in which the number of processors changed dynamically on demand and tasks were migrated according to unexpected faults. The paper presents the application of the framework to the study of nanoenergetic materials: (1) combustion of an Al/Fe2O3 thermite and (2) shock initiation and reactive nanojets at a void in an energetic crystal.

GOBF-ARMA based model predictive control for an ideal reactive distillation column.

PubMed

Seban, Lalu; Kirubakaran, V; Roy, B K; Radhakrishnan, T K

2015-11-01

This paper discusses the control of an ideal reactive distillation column (RDC) using model predictive control (MPC) based on a combination of deterministic generalized orthonormal basis filter (GOBF) and stochastic autoregressive moving average (ARMA) models. Reactive distillation (RD) integrates reaction and distillation in a single process resulting in process and energy integration promoting green chemistry principles. Improved selectivity of products, increased conversion, better utilization and control of reaction heat, scope for difficult separations and the avoidance of azeotropes are some of the advantages that reactive distillation offers over conventional technique of distillation column after reactor. The introduction of an in situ separation in the reaction zone leads to complex interactions between vapor-liquid equilibrium, mass transfer rates, diffusion and chemical kinetics. RD with its high order and nonlinear dynamics, and multiple steady states is a good candidate for testing and verification of new control schemes. Here a combination of GOBF-ARMA models is used to catch and represent the dynamics of the RDC. This GOBF-ARMA model is then used to design an MPC scheme for the control of product purity of RDC under different operating constraints and conditions. The performance of proposed modeling and control using GOBF-ARMA based MPC is simulated and analyzed. The proposed controller is found to perform satisfactorily for reference tracking and disturbance rejection in RDC. Copyright © 2015 Elsevier Inc. All rights reserved.

Distributed Patterns of Reactivation Predict Vividness of Recollection.

PubMed

St-Laurent, Marie; Abdi, Hervé; Buchsbaum, Bradley R

2015-10-01

According to the principle of reactivation, memory retrieval evokes patterns of brain activity that resemble those instantiated when an event was first experienced. Intuitively, one would expect neural reactivation to contribute to recollection (i.e., the vivid impression of reliving past events), but evidence of a direct relationship between the subjective quality of recollection and multiregional reactivation of item-specific neural patterns is lacking. The current study assessed this relationship using fMRI to measure brain activity as participants viewed and mentally replayed a set of short videos. We used multivoxel pattern analysis to train a classifier to identify individual videos based on brain activity evoked during perception and tested how accurately the classifier could distinguish among videos during mental replay. Classification accuracy correlated positively with memory vividness, indicating that the specificity of multivariate brain patterns observed during memory retrieval was related to the subjective quality of a memory. In addition, we identified a set of brain regions whose univariate activity during retrieval predicted both memory vividness and the strength of the classifier's prediction irrespective of the particular video that was retrieved. Our results establish distributed patterns of neural reactivation as a valid and objective marker of the quality of recollection.

Startle Potentiation to Uncertain Threat as a Psychophysiological Indicator of Fear-based Psychopathology: An Examination across Multiple Internalizing Disorders

PubMed Central

Gorka, Stephanie M.; Lieberman, Lynne; Shankman, Stewart A.; Phan, K. Luan

2016-01-01

Heightened reactivity to uncertain threat (U-threat) is an important individual difference factor that may characterize fear-based internalizing psychopathologies (IPs) and distinguish them from distress/misery IPs. To date, however, the majority of existing research examining reactivity to U-threat has been within individuals with panic disorder and major depressive disorder (MDD) and no prior study has directly tested this hypothesis across multiple IPs. The current study therefore explored whether heightened reactivity to U-threat is a psychophysiological indicator of fear-based psychopathology across five groups: current 1) social anxiety disorder (SAD), 2) specific phobia (SP), 3) generalized anxiety disorder (GAD), 4) MDD, and 5) individuals with no history of psychopathology (controls). All 160 adults completed a well-validated threat-of-shock task designed to probe responses to predictable (P-) and U-threat. Startle eyeblink potentiation was recorded as an index of aversive arousal. Results indicated that individuals with SAD and SP evidenced greater startle potentiation to U-threat, but not P-threat, relative to individuals with GAD, MDD and controls (who did not differ). The current findings, along with the prior panic disorder and MDD literature, suggest that heightened reactivity to U-threat is a psychophysiological indicator of fear-based disorders and could represent a neurobiological organizing principle for internalizing psychopathology. The findings also suggest that individuals with fear disorders generally display a hypersensitivity to uncertain aversive events, which could contribute to their psychopathology. PMID:27868423

Morphology and Surface Reactivity Relationship in the Li1+xMn2-xO4 Spinel with x = 0.05 and 0.10: A Combined First-Principle and Experimental Study.

PubMed

Quesne-Turin, Ambroise; Vallverdu, Germain; Flahaut, Delphine; Allouche, Joachim; Croguennec, Laurence; Ménétrier, Michel; Baraille, Isabelle

2017-12-27

This article focuses on the surface reactivity of two spinel samples with different stoichiometries and crystal morphologies, namely Li 1+x Mn 2-x O 4 with x = 0.05 and 0.10. LiMn 2 O 4 compounds are good candidates as positive electrode of high-power lithium-ion batteries for portable devices. The samples were investigated using both experimental and theoretical approaches. On the experimental point of view, they were characterized in depth from X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) analyses. Then, the reactivity was investigated through the adsorption of (SO 2 ) gaseous probes, in controlled conditions, followed by XPS characterization. First-principle calculations were conducted simultaneously to investigate the electronic properties and the reactivity of relevant surfaces of an ideal LiMn 2 O 4 material. The results allow us to conclude that the reactivity of the samples is dominated by an acido-basic reactivity and the formation of sulfite species. Nonetheless, on the x = 0.05 sample, both sulfite and sulfate species are obtained, the later, in lesser extent, corresponding to a redox reactivity. Combining experimental and theoretical results, this redox reactivity could be associated with the presence of a larger quantity of Mn 4+ cations on the last surface layers of the material linked to a specific surface orientation.

Improving Pharmacy Students' Understanding and Long-term Retention of Acid-Base Chemistry

PubMed Central

2007-01-01

Despite repeated exposure to the principles underlying the behavior of organic acids and bases in aqueous solution, some pharmacy students remain confused about the topic of acid-base chemistry. Since a majority of organic drug molecules have acid-base character, the ability to predict their reactivity and the extent to which they will ionize in a given medium is paramount to students' understanding of essentially all aspects of drug action in vivo and in vitro. This manuscript presents a medicinal chemistry lesson in the fundamentals of acid-base chemistry that many pharmacy students have found enlightening and clarifying PMID:19503706

Using Paraquat to Generate Anion Free Radicals and Hydrogen Peroxide in "In Vitro": Antioxidant Effect of Vitamin E--A Procedure to Teach Theoretical and Experimental Principles of Reactive Oxygen Species Biochemistry

ERIC Educational Resources Information Center

Jimenez-Del-Rio, Marlene; Suarez-Cedeno, Gerson; Velez-Pardo, Carlos

2010-01-01

The theoretical basis of reactive oxygen species and their impact on health issues are relatively easy to understand by biomedical students. The detection of reactive oxygen species requires expensive equipment, the procedures are time consuming and costly, and the results are hard to interpret. Moreover, cause-and-effect relationships in the…

HIV-1 Vaccines Based on Antibody Identification, B Cell Ontogeny, and Epitope Structure.

PubMed

Kwong, Peter D; Mascola, John R

2018-05-15

HIV-1 vaccine development has been stymied by an inability to induce broadly reactive neutralizing antibodies to the envelope (Env) trimer, the sole viral antigen on the virion surface. Antibodies isolated from HIV-1-infected donors, however, have been shown to recognize all major exposed regions of the prefusion-closed Env trimer, and an emerging understanding of the immunological and structural characteristics of these antibodies and the epitopes they recognize is enabling new approaches to vaccine design. Antibody lineage-based design creates immunogens that activate the naive ancestor-B cell of a target antibody lineage and that mature intermediate-B cells toward effective neutralization, with proof of principle achieved with select HIV-1-neutralizing antibody lineages in human-gene knock-in mouse models. Epitope-based vaccine design involves the engineering of sites of Env vulnerability as defined by the recognition of broadly neutralizing antibodies, with cross-reactive neutralizing antibodies elicited in animal models. Both epitope-based and antibody lineage-based HIV-1 vaccine approaches are being readied for human clinical trials. Published by Elsevier Inc.

Startle potentiation to uncertain threat as a psychophysiological indicator of fear-based psychopathology: An examination across multiple internalizing disorders.

PubMed

Gorka, Stephanie M; Lieberman, Lynne; Shankman, Stewart A; Phan, K Luan

2017-01-01

Heightened reactivity to uncertain threat (U-threat) is an important individual difference factor that may characterize fear-based internalizing psychopathologies (IPs) and distinguish them from distress/misery IPs. To date, however, the majority of existing research examining reactivity to U-threat has been within individuals with panic disorder and major depressive disorder (MDD) and no prior study has directly tested this hypothesis across multiple IPs. The current study therefore explored whether heightened reactivity to U-threat is a psychophysiological indicator of fear-based psychopathology across 5 groups: current (a) social anxiety disorder (SAD); (b) specific phobia (SP); (c) generalized anxiety disorder (GAD); (d) MDD; and (c) individuals with no history of psychopathology (controls). All 160 adults completed a well-validated threat-of-shock task designed to probe responses to predictable (P-) and U-threat. Startle eyeblink potentiation was recorded as an index of aversive arousal. Results indicated that individuals with SAD and SP evidenced greater startle potentiation to U-threat, but not P-threat, relative to individuals with GAD, MDD, and controls (who did not differ). The current findings, along with the prior panic disorder and MDD literature, suggest that heightened reactivity to U-threat is a psychophysiological indicator of fear-based disorders and could represent a neurobiological organizing principle for internalizing psychopathology. The findings also suggest that individuals with fear disorders generally display a hypersensitivity to uncertain aversive events, which could contribute to their psychopathology. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Predictive sufficiency and the use of stored internal state

NASA Technical Reports Server (NTRS)

Musliner, David J.; Durfee, Edmund H.; Shin, Kang G.

1994-01-01

In all embedded computing systems, some delay exists between sensing and acting. By choosing an action based on sensed data, a system is essentially predicting that there will be no significant changes in the world during this delay. However, the dynamic and uncertain nature of the real world can make these predictions incorrect, and thus, a system may execute inappropriate actions. Making systems more reactive by decreasing the gap between sensing and action leaves less time for predictions to err, but still provides no principled assurance that they will be correct. Using the concept of predictive sufficiency described in this paper, a system can prove that its predictions are valid, and that it will never execute inappropriate actions. In the context of our CIRCA system, we also show how predictive sufficiency allows a system to guarantee worst-case response times to changes in its environment. Using predictive sufficiency, CIRCA is able to build real-time reactive control plans which provide a sound basis for performance guarantees that are unavailable with other reactive systems.

Compartmental and Data-Based Modeling of Cerebral Hemodynamics: Linear Analysis.

PubMed

Henley, B C; Shin, D C; Zhang, R; Marmarelis, V Z

Compartmental and data-based modeling of cerebral hemodynamics are alternative approaches that utilize distinct model forms and have been employed in the quantitative study of cerebral hemodynamics. This paper examines the relation between a compartmental equivalent-circuit and a data-based input-output model of dynamic cerebral autoregulation (DCA) and CO2-vasomotor reactivity (DVR). The compartmental model is constructed as an equivalent-circuit utilizing putative first principles and previously proposed hypothesis-based models. The linear input-output dynamics of this compartmental model are compared with data-based estimates of the DCA-DVR process. This comparative study indicates that there are some qualitative similarities between the two-input compartmental model and experimental results.

General Semantics in the Labor Room.

ERIC Educational Resources Information Center

Keller, Jo

This paper provides a review of some basic general semantic principles and then applies them to the area of prenatal classes and labor room practices. It first presents an overview of the principle that language is not a neutral factor in human perceptions but an active, reactive force. Next, it looks at the relationship between language and…

A generalized operational formula based on total electronic densities to obtain 3D pictures of the dual descriptor to reveal nucleophilic and electrophilic sites accurately on closed-shell molecules.

PubMed

Martínez-Araya, Jorge I

2016-09-30

By means of the conceptual density functional theory, the so-called dual descriptor (DD) has been adapted to be used in any closed-shell molecule that presents degeneracy in its frontier molecular orbitals. The latter is of paramount importance because a correct description of local reactivity will allow to predict the most favorable sites on a molecule to undergo nucleophilic or electrophilic attacks; on the contrary, an incomplete description of local reactivity might have serio us consequences, particularly for those experimental chemists that have the need of getting an insight about reactivity of chemical reagents before using them in synthesis to obtain a new compound. In the present work, the old approach based only on electronic densities of frontier molecular orbitals is replaced by the most accurate procedure that implies the use of total electronic densities thus keeping consistency with the essential principle of the DFT in which the electronic density is the fundamental variable and not the molecular orbitals. As a result of the present work, the DD will be able to properly describe local reactivities only in terms of total electronic densities. To test the proposed operational formula, 12 very common molecules were selected as the original definition of the DD was not able to describe their local reactivities properly. The ethylene molecule was additionally used to test the capability of the proposed operational formula to reveal a correct local reactivity even in absence of degeneracy in frontier molecular orbitals. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Chemical reactivity parameters (HSAB) applied to magma evolution and ore formation

NASA Astrophysics Data System (ADS)

Vigneresse, Jean-Louis

2012-11-01

Magmas are commonly described through the usual content of 10 major oxides. This requires a complex dimensional plot. Concepts of hard-soft acid-base (HSAB) interactions allow estimating chemical reactivity of elements, such as electronegativity, i.e. the chemical potential changed of sign, hardness and electrophilicity. For complex system, those values result from equalization methods, i.e. the equalization of the respective chemical potentials, or from ab-initio computations through density functional theory (DFT). They help to characterize silicate magmas by a single value describing their reactivity. Principles of minimum electrophilicity (mEP), maximum hardness (MHP) and minimum polarizability (mPP) indicate trends towards regions of higher stability. Those parameters are plotted within a fitness landscape diagram, highlighting toward which principle reactions trend. Major oxides, main minerals and magmas determine the respective fields in which evolve natural rocks. Three poles are identified, represented by silica and alkalis, whereas oxidation forms the third trend. Mantle-derived rocks show a large variation in electrophilicity compared to hardness. They present all characters of a closed chemical system, being simply described by the free Gibbs energy. Conversely, rocks contaminated within the continental crust show a large variation in hardness between a silica pole and an alkaline, defining two separate trends. The trends show the character of an open chemical system, requiring a Grand Potential description (i.e. taking into account the difference in chemical potential). The terms open and closed systems refer to thermodynamical description, implying contamination for the crust and recycling for the mantle. The specific role of alkalis contrasts with other cations, pointing to their behavior in modifying silicate polymer structures. A second application deals with the reactivity of the melt and its fluid phase. It leads to a better understanding on the mechanisms that control sequestration and transport of metals within the different phases during igneous activity. Based on high gas/melt partitioning for metals and similar reactivity, the gaseous phase is more attractive for metals than silicate melts. The presence of halogens in the fluid phase tends to reinforce hardness, making the fluid phase attractive for hard metals such as Sn or W. Conversely, the presence of S decreases hardness of the fluid phase that becomes attractive for soft metals such as Au, Ag and Cu.

A new optical method for a fast and simple detection of ephedrine

NASA Astrophysics Data System (ADS)

Varriale, Antonio; Staiano, Maria; Strianese, Maria; Marzullo, Vincenzo; Ruggiero, Giuseppe; Secchi, Alberto; Dispenza, Massimiliano; Fiorello, Anna Maria; D'Auria, Sabato

2011-11-01

In this work we describe the synthesis of a new ephedrine derivative with a carbon linker featuring an amino reactive group, and its conjugation to the glutamine binding protein (GlnBP) from E. coli as a carrier protein for the production of polyclonal antibodies in rabbits against ephedrine. Proof-of-principle results that an efficient SPR-based indirect competitive immunoassay for the detection and quantification of ephedrine are presented. The detection limit of this assay was found to be about 33ng/ml.

Proton transfer from water to ketyl radical anion: Assessment of critical size of hydrated cluster and free energy barrier in solution from first principles simulations

NASA Astrophysics Data System (ADS)

Biswas, Sohag; Dasgupta, Teesta; Mallik, Bhabani S.

2016-09-01

We present the reactivity of an organic intermediate by studying the proton transfer process from water to ketyl radical anion using gas phase electronic structure calculations and the metadynamics method based first principles molecular dynamics (FPMD) simulations. Our results indicate that during the micro solvation of anion by water molecules systematically, the presence of minimum three water molecules in the gas phase cluster is sufficient to observe the proton transfer event. The analysis of trajectories obtained from initial FPMD simulation of an aqueous solution of the anion does not show any evident of complete transfer of the proton from water. The cooperativity of water molecules and the relatively weak anion-water interaction in liquid state prohibit the full release of the proton. Using biasing potential through first principles metadynamics simulations, we report the observation of proton transfer reaction from water to ketyl radical anion with a barrier height of 16.0 kJ/mol.

Conformer-specific hydrogen atom tunnelling in trifluoromethylhydroxycarbene

NASA Astrophysics Data System (ADS)

Mardyukov, Artur; Quanz, Henrik; Schreiner, Peter R.

2017-01-01

Conformational control of organic reactions is at the heart of the biomolecular sciences. To achieve a particular reactivity, one of many conformers may be selected, for instance, by a (bio)catalyst, as the geometrically most suited and appropriately reactive species. The equilibration of energetically close-lying conformers is typically assumed to be facile and less energetically taxing than the reaction under consideration itself: this is termed the 'Curtin-Hammett principle'. Here, we show that the trans conformer of trifluoromethylhydroxycarbene preferentially rearranges through a facile quantum-mechanical hydrogen tunnelling pathway, while its cis conformer is entirely unreactive. Hence, this presents the first example of a conformer-specific hydrogen tunnelling reaction. The Curtin-Hammett principle is not applicable, due to the high barrier between the two conformers.

Electrostatically Levitated Ring-Shaped Rotational-Gyro/Accelerometer

NASA Astrophysics Data System (ADS)

Murakoshi, Takao; Endo, Yasuo; Fukatsu, Keisuke; Nakamura, Sigeru; Esashi, Masayoshi

2003-04-01

This paper reports an electrostatically levitated inertia measurement system which is based on the principle of a rotational gyro. The device has several advantages: the levitation of the rotor in a vacuum eliminates mechanical friction resulting in high sensitivity; the position control for the levitation allows accelerations to be sensed in the tri-axis; and the fabrication of the device by a micromachining technique has the cost advantages afforded by miniaturization. Latest measurements yield a noise floor of the gyro and that of the accelerometer as low as 0.15 deg/h1/2 and 30 μG/Hz1/2, respectively. This performance is achieved by a new sensor design. To further improve of the previous device, a ring-shaped structure is designed and fabricated by deep reactive ion etching using inductively coupled plasma. The rotor levitation is performed with capacitive detection and electrostatic actuation. Multiaxis closed-loop control is realized by differential capacitance sensing and frequency multiplying. The rotation of the micro gyro is based on the principle of a planar variable capacitance motor.

Social cognitive theory, metacognition, and simulation learning in nursing education.

PubMed

Burke, Helen; Mancuso, Lorraine

2012-10-01

Simulation learning encompasses simple, introductory scenarios requiring response to patients' needs during basic hygienic care and during situations demanding complex decision making. Simulation integrates principles of social cognitive theory (SCT) into an interactive approach to learning that encompasses the core principles of intentionality, forethought, self-reactiveness, and self-reflectiveness. Effective simulation requires an environment conducive to learning and introduces activities that foster symbolic coding operations and mastery of new skills; debriefing builds self-efficacy and supports self-regulation of behavior. Tailoring the level of difficulty to students' mastery level supports successful outcomes and motivation to set higher standards. Mindful selection of simulation complexity and structure matches course learning objectives and supports progressive development of metacognition. Theory-based facilitation of simulated learning optimizes efficacy of this learning method to foster maturation of cognitive processes of SCT, metacognition, and self-directedness. Examples of metacognition that are supported through mindful, theory-based implementation of simulation learning are provided. Copyright 2012, SLACK Incorporated.

Comparative analysis of the designs and implementation of vehicles based on reactive propulsion proposed during the nineteenth and beginning of the twentieth centuries

NASA Technical Reports Server (NTRS)

Sokolskiy, V. N.

1977-01-01

Examination of the presently known historical scientific literature related to the problem of reactive flight indicates that considerable attention had already been given to the idea of reactive propulsion in the nineteenth century; about thirty designs for reaction flying vehicles were proposed during this period. However, the authors of a majority of the designs limited themselves only to a presentation of a diagram of the engine or an account of the principle of its operation, giving neither plans for its structural development nor precise calculations of the amount of energy required for accomplishing reaction flight. None of these authors considered the reaction flying vehicle as an object of variable mass, their choice of energy sources was extremely random, and the theory of the flight of reaction flying vehicles remained completely undeveloped. Early rocket designs of Nezhdanovsky, Ganswindt, Goddard, Tsiolkovsky, and others are examined and the evolution of liquid-propellant rocket engines, solid-propellant rocket engines, and jet aircraft engines is reviewed.

Oxygen plasma etching of graphene: A first-principles dynamical inspection of the reaction mechanisms and related activation barriers

NASA Astrophysics Data System (ADS)

Koizumi, Kenichi; Boero, Mauro; Shigeta, Yasuteru; Oshiyama, Atsushi; Dept. of Applied Physics Team; Institute of Physics and Chemistry of Strasbourg (IPCMS) Collaboration; Department Of Materials Engineering Science Collaboration

2013-03-01

Oxygen plasma etching is a crucial step in the fabrication of electronic circuits and has recently received a renovated interest in view of the realization of carbon-based nanodevices. In an attempt at unraveling the atomic-scale details and to provide guidelines for the control of the etching processes mechanisms, we inspected the possible reaction pathways via reactive first principles simulations. These processes involve breaking and formation of several chemical bonds and are characterized by different free-energy barriers. Free-energy sampling techniques (metadynamics and blue moon), used to enhance the standard Car-Parrinello molecular dynamics, provide us a detailed microscopic picture of the etching of graphene surfaces and a comprehensive scenario of the activation barriers involved in the various steps. MEXT, Japan - contract N. 22104005

Relative reactivity of amino acids with chlorine in mixtures.

PubMed

Na, Chongzheng; Olson, Terese M

2007-05-01

The relative reactivity of chlorine with amino acids is an important determinant of the resulting chlorination products in systems where chlorine is the limiting reagent, for example, in the human gastrointestinal tract after consumption of chlorine-containing water, or during food preparation with chlorinated water. Since few direct determinations of the initial reactivity of chlorine with amino acids have been made, 17 amino acids were compared in this study using competitive kinetic principles. The experimental results showed that (1) most amino acids have similar initial reactivities at neutral pH; (2) amino acids with thiol groups such as methionine and cysteine are exceptionally reactive and produce sulfoxides; (3) amino acids without thiol groups primarily undergo monochlorination of the amino nitrogen; and (4) glycine and proline are the least reactive. Dichlorination was estimated to occur with approximately 26% of the amino acid groups when the total amino acid: chlorine concentrations were equal.

Concept and numerical simulations of a reactive anti-fragment armour layer

NASA Astrophysics Data System (ADS)

Hušek, Martin; Kala, Jiří; Král, Petr; Hokeš, Filip

2017-07-01

The contribution describes the concept and numerical simulation of a ballistic protective layer which is able to actively resist projectiles or smaller colliding fragments flying at high speed. The principle of the layer was designed on the basis of the action/reaction system of reactive armour which is used for the protection of armoured vehicles. As the designed ballistic layer consists of steel plates simultaneously combined with explosive material - primary explosive and secondary explosive - the technique of coupling the Finite Element Method with Smoothed Particle Hydrodynamics was used for the simulations. Certain standard situations which the ballistic layer should resist were simulated. The contribution describes the principles for the successful execution of numerical simulations, their results, and an evaluation of the functionality of the ballistic layer.

Biological Chemistry and Functionality of Protein Sulfenic Acids and Related Thiol Modifications

PubMed Central

Devarie-Baez, Nelmi O.; Silva Lopez, Elsa I.; Furdui, Cristina M.

2016-01-01

Selective modification of proteins at cysteine residues by reactive oxygen, nitrogen or sulfur species formed under physiological and pathological states is emerging as a critical regulator of protein activity impacting cellular function. This review focuses primarily on protein sulfenylation (-SOH), a metastable reversible modification connecting reduced cysteine thiols to many products of cysteine oxidation. An overview is first provided on the chemistry principles underlining synthesis, stability and reactivity of sulfenic acids in model compounds and proteins, followed by a brief description of analytical methods currently employed to characterize these oxidative species. The following chapters present a selection of redox-regulated proteins for which the -SOH formation was experimentally confirmed and linked to protein function. These chapters are organized based on the participation of these proteins in the regulation of signaling, metabolism and epigenetics. The last chapter discusses the therapeutic implications of altered redox microenvironment and protein oxidation in disease. PMID:26340608

Degradation of Alkali-Based Photocathodes from Exposure to Residual Gases: A First-Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Gaoxue; Pandey, Ravindra; Moody, Nathan A.

Photocathodes are a key component in the production of electron beams in systems such as X-ray free-electron lasers and X-ray energy-recovery linacs. Alkali-based materials display high quantum efficiency (QE), however, their QE undergoes degradation faster than metal photocathodes even in the high vacuum conditions where they operate. The high reactivity of alkali-based surfaces points to surface reactions with residual gases as one of the most important factors for the degradation of QE. In order to advance the understanding on the degradation of the QE, we investigated the surface reactivity of common residual gas molecules (e.g., O 2, CO 2, CO,more » H 2O, N 2, and H 2) on one of the best-known alkali-based photocathode materials, cesium antimonide (Cs 3Sb), using first-principles calculations based on density functional theory. Furthermore, the reaction sites, adsorption energy, and effect in the local electronic structure upon reaction of these molecules on (001), (110), and (111) surfaces of Cs 3Sb were computed and analyzed. The adsorption energy of these molecules on Cs3Sb follows the trend of O 2 (-4.5 eV) > CO 2 (-1.9 eV) > H 2O (-1.0 eV) > CO (-0.8 eV) > N 2 (-0.3 eV) ≈ H 2 (-0.2 eV), which agrees with experimental data on the effect of these gases on the degradation of QE. The interaction strength is determined by the charge transfer from the surfaces to the molecules. The adsorption and dissociation of O containing molecules modify the surface chemistry such as the composition, structure, charge distribution, surface dipole, and work function of Cs 3Sb, resulting in the degradation of QE with exposure to O 2, CO 2, H 2O, and CO.« less

Degradation of Alkali-Based Photocathodes from Exposure to Residual Gases: A First-Principles Study

DOE PAGES

Wang, Gaoxue; Pandey, Ravindra; Moody, Nathan A.; ...

2017-03-31

Photocathodes are a key component in the production of electron beams in systems such as X-ray free-electron lasers and X-ray energy-recovery linacs. Alkali-based materials display high quantum efficiency (QE), however, their QE undergoes degradation faster than metal photocathodes even in the high vacuum conditions where they operate. The high reactivity of alkali-based surfaces points to surface reactions with residual gases as one of the most important factors for the degradation of QE. In order to advance the understanding on the degradation of the QE, we investigated the surface reactivity of common residual gas molecules (e.g., O 2, CO 2, CO,more » H 2O, N 2, and H 2) on one of the best-known alkali-based photocathode materials, cesium antimonide (Cs 3Sb), using first-principles calculations based on density functional theory. Furthermore, the reaction sites, adsorption energy, and effect in the local electronic structure upon reaction of these molecules on (001), (110), and (111) surfaces of Cs 3Sb were computed and analyzed. The adsorption energy of these molecules on Cs3Sb follows the trend of O 2 (-4.5 eV) > CO 2 (-1.9 eV) > H 2O (-1.0 eV) > CO (-0.8 eV) > N 2 (-0.3 eV) ≈ H 2 (-0.2 eV), which agrees with experimental data on the effect of these gases on the degradation of QE. The interaction strength is determined by the charge transfer from the surfaces to the molecules. The adsorption and dissociation of O containing molecules modify the surface chemistry such as the composition, structure, charge distribution, surface dipole, and work function of Cs 3Sb, resulting in the degradation of QE with exposure to O 2, CO 2, H 2O, and CO.« less

SU-E-T-191: First Principle Calculation of Quantum Yield in Photodynamic Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abolfath, R; Guo, F; Chen, Z

Purpose: We present a first-principle method to calculate the spin transfer efficiency in oxygen induced by any photon fields especially in MeV energy range. The optical pumping is mediated through photosensitizers, e.g., porphyrin and/or ensemble of quantum dots. Methods: Under normal conditions, oxygen molecules are in the relatively non-reactive triplet state. In the presence of certain photosensitizer compounds such as porphyrins, electromagnetic radiation of specific wavelengths can excite oxygen to highly reactive singlet state. With selective uptake of photosensitizers by certain malignant cells, photon irradiation of phosensitized tumors can lead to selective killing of cancer cells. This is the basismore » of photodynamic therapy (PDT). Despite several attempts, PDT has not been clinically successful except in limited superficial cancers. Many parameters such as photon energy, conjugation with quantum dots etc. can be potentially combined with PDT in order to extend the role of PDT in cancer management. The key quantity for this optimization is the spin transfer efficiency in oxygen by any photon field. The first principle calculation model presented here, is an attempt to fill this need. We employ stochastic density matrix description of the quantum jumps and the rate equation methods in quantum optics based on Markov/Poisson processes and calculate time evolution of the population of the optically pumped singlet oxygen. Results: The results demonstrate the feasibility of our model in showing the dependence of the optical yield in generating spin-singlet oxygen on the experimental conditions. The adjustable variables can be tuned to maximize the population of the singlet oxygen hence the efficacy of the photodynamic therapy. Conclusion: The present model can be employed to fit and analyze the experimental data and possibly to assist researchers in optimizing the experimental conditions in photodynamic therapy.« less

Mirrored continuum and molecular scale simulations of the ignition of gamma phase RDX

NASA Astrophysics Data System (ADS)

Stewart, D. Scott; Chaudhuri, Santanu; Joshi, Kaushik; Lee, Kiabek

2015-06-01

We consider the ignition of a high-pressure gamma-phase of an explosive crystal of RDX which forms during overdriven shock initiation. Molecular dynamics (MD), with first-principles based or reactive force field based molecular potentials, provides a description of the chemistry as an extremely complex reaction network. The results of the molecular simulation is analyzed by sorting molecular product fragments into high and low molecular groups, to represent identifiable components that can be interpreted by a continuum model. A continuum model based on a Gibbs formulation, that has a single temperature and stress state for the mixture is used to represent the same RDX material and its chemistry. Each component in the continuum model has a corresponding Gibbs continuum potential, that are in turn inferred from molecular MD informed equation of state libraries such as CHEETAH, or are directly simulated by Monte Carlo MD simulations. Information about transport, kinetic rates and diffusion are derived from the MD simulation and the growth of a reactive hot spot in the RDX is studied with both simulations that mirror the other results to provide an essential, continuum/atomistic link. Supported by N000014-12-1-0555, subaward-36561937 (ONR).

The interaction of a gold atom with carbon nanohorn and carbon nanotube tips and their complexes with a CO molecule: A first principle calculation

NASA Astrophysics Data System (ADS)

Khongpracha, P.; Probst, M.; Limtrakul, J.

2008-07-01

The interactions of a gold atom with: (a) a single-wall carbon nanohorn (SWNH) conic tip; (b) with a single-wall carbon nanotube (SWNT) tip; and (c) their complexes with a CO molecule were studied using first-principle calculations based on density functional theory. The analysis of the pyramidalization angle (θp) as well as the π-orbital misalignment angles indicate that there should be many reactive carbon sites on the tips of SWNH and SWNT. It was found that SWNH provides reactive sites that can more selectively interact with the target atom. We identified five sites on both the SWNT tip and the nanohorn where attachment of a gold atom leads to a stable complex. This metal is found to be bi-coordinated with the tip of SWNH, while it is mono-coordinated with the SWNT tip. The largest interaction energies are -10.75 kcal/mol and -16.17 kcal/mol, respectively. The CO probe molecule binds to Au on the Au/SWNH or Au/SWNT tips with interaction energies of -22.34 and -18.29 kcal/mol, respectively. The main contributions of the interaction with both carbon nanostructures stems from σ-donation and π-backbonding. The results suggest that SWNHs could be one of the promising candidates for the development of high-specifity nanosensors.

Modifying Memory for a Museum Tour in Older Adults: Reactivation-Related Updating that Enhances and Distorts Memory is Reduced in Aging

PubMed Central

St Jacques, Peggy L.; Montgomery, Daniel; Schacter, Daniel L.

2015-01-01

Memory reactivation, the activation of a latent memory trace when we are reminded of a past experience, strengthens memory but can also contribute to distortions if new information present during reactivation is integrated with existing memory. In a previous study in young adults we found that the quality of memory reactivation, manipulated using the principle of encoding specificity and indexed by recollection ratings, modulated subsequent true and false memories for events experienced during a museum tour. Here, we examined age-related changes in the quality of memory reactivation on subsequent memory. Young and older adults reactivated memories for museum stops immediately followed by the presentation of a novel lure photo from an alternate tour version (i.e., reactivation plus new information). There was an increase in subsequent true memories for reactivated targets and for subsequent false memories for lures that followed reactivated targets, when compared to baseline target and lure photos. However, the influence of reactivation on subsequent memories was reduced in older adults. These data reveal that aging alters reactivation-related updating processes that allow memories to be strengthened and updated with new information-consequently reducing memory distortions in older compared to young adults. PMID:24993055

Modifying memory for a museum tour in older adults: Reactivation-related updating that enhances and distorts memory is reduced in ageing.

PubMed

St Jacques, Peggy L; Montgomery, Daniel; Schacter, Daniel L

2015-01-01

Memory reactivation, the activation of a latent memory trace when we are reminded of a past experience, strengthens memory but can also contribute to distortions if new information present during reactivation is integrated with existing memory. In a previous study in young adults we found that the quality of memory reactivation, manipulated using the principle of encoding specificity and indexed by recollection ratings, modulated subsequent true and false memories for events experienced during a museum tour. Here in this study, we examined age-related changes in the quality of memory reactivation on subsequent memory. Memories of museum stops in young and older adults were reactivated and then immediately followed by the presentation of a novel lure photo from an alternate tour version (i.e., reactivation plus new information). There was an increase in subsequent true memories for reactivated targets and for subsequent false memories for lures that followed reactivated targets, when compared to baseline target and lure photos. However, the influence of reactivation on subsequent memories was reduced in older adults. These data reveal that ageing alters reactivation-related updating processes that allow memories to be strengthened and updated with new information, consequently reducing memory distortions in older adults compared to young adults.

Decline in Cue-Provoked Craving During Cue Exposure Therapy for Smoking Cessation

PubMed Central

Unrod, Marina; Drobes, David J.; Stasiewicz, Paul R.; Ditre, Joseph W.; Heckman, Bryan; Miller, Ralph R.; Sutton, Steven K.

2014-01-01

Introduction: Based on the principles of Pavlovian learning and extinction, cue exposure therapy (CET) involves repeated exposure to substance-associated cues to extinguish conditioned cravings and reduce the likelihood of relapse. The efficacy of CET is predicated on successful extinction, yet the process of extinction in CET trials has rarely been demonstrated. This study explored the extinction process using a cue-reactivity paradigm in smokers undergoing multiple CET sessions as part of a comprehensive smoking cessation treatment. Methods: The sample comprised 76 moderately dependent, treatment-seeking smokers who completed at least 4 CET sessions and 6 counseling sessions. The CET and counseling sessions were scheduled twice weekly, and participants began using transdermal nicotine replacement therapy on their quit day, which occurred prior to initiation of CET. Each CET session consisted of presentation of 140 images on a computer screen, with self-reported craving as the primary measure of cue reactivity. Results: Mixed-model analyses revealed a progressive decline in cue-provoked craving both within and across 6 sessions of CET. Moderator analyses showed that the decline in craving was greatest among those who displayed initial cue reactivity. Conclusions: These data are consistent with the premise that CET can produce extinction of laboratory-based cue-provoked smoking cravings and highlight important individual differences that may influence extinction. Implications for conducting cue exposure research and interventions are discussed. PMID:24078760

Reactive Molecular Dynamics Simulations to Understand Mechanical Response of Thaumasite under Temperature and Strain Rate Effects.

PubMed

Hajilar, Shahin; Shafei, Behrouz; Cheng, Tao; Jaramillo-Botero, Andres

2017-06-22

Understanding the structural, thermal, and mechanical properties of thaumasite is of great interest to the cement industry, mainly because it is the phase responsible for the aging and deterioration of civil infrastructures made of cementitious materials attacked by external sources of sulfate. Despite the importance, effects of temperature and strain rate on the mechanical response of thaumasite had remained unexplored prior to the current study, in which the mechanical properties of thaumasite are fully characterized using the reactive molecular dynamics (RMD) method. With employing a first-principles based reactive force field, the RMD simulations enable the description of bond dissociation and formation under realistic conditions. From the stress-strain curves of thaumasite generated in the x, y, and z directions, the tensile strength, Young's modulus, and fracture strain are determined for the three orthogonal directions. During the course of each simulation, the chemical bonds undergoing tensile deformations are monitored to reveal the bonds responsible for the mechanical strength of thaumasite. The temperature increase is found to accelerate the bond breaking rate and consequently the degradation of mechanical properties of thaumasite, while the strain rate only leads to a slight enhancement of them for the ranges considered in this study.

Reactive documentation system

NASA Astrophysics Data System (ADS)

Boehnlein, Thomas R.; Kramb, Victoria

2018-04-01

Proper formal documentation of computer acquired NDE experimental data generated during research is critical to the longevity and usefulness of the data. Without documentation describing how and why the data was acquired, NDE research teams lose capability such as their ability to generate new information from previously collected data or provide adequate information so that their work can be replicated by others seeking to validate their research. Despite the critical nature of this issue, NDE data is still being generated in research labs without appropriate documentation. By generating documentation in series with data, equal priority is given to both activities during the research process. One way to achieve this is to use a reactive documentation system (RDS). RDS prompts an operator to document the data as it is generated rather than relying on the operator to decide when and what to document. This paper discusses how such a system can be implemented in a dynamic environment made up of in-house and third party NDE data acquisition systems without creating additional burden on the operator. The reactive documentation approach presented here is agnostic enough that the principles can be applied to any operator controlled, computer based, data acquisition system.

First Principles Based Reactive Atomistic Simulations to Understand the Effects of Molecular Hypervelocity Impact on Cassini's Ion and Neutral Mass Spectrometer

NASA Technical Reports Server (NTRS)

Jaramillo-Botero, A.; Cheng, M-J; Cvicek, V.; Beegle, Luther W.; Hodyss, R.; Goddard, W. A., III

2011-01-01

We report here on the predicted impact of species such as ice-water, CO2, CH4, and NH3, on oxidized titanium, as well as HC species on diamond surfaces. These simulations provide the dynamics of product distributions during and after a hypervelocity impact event, ionization fractions, and dissociation probabilities for the various species of interest as a function of impact velocity (energy). We are using these results to determine the relevance of the fragmentation process to Cassini INMS results, and to quantify its effects on the observed spectra.

Changes of rat plasma total low molecular weight antioxidant level after tabun exposure and consequent treatment by acetylcholinesterase reactivators.

PubMed

Pohanka, Miroslav; Karasova, Jana Zdarova; Musilek, Kamil; Kuca, Kamil; Jung, Young-Sik; Kassa, Jiri

2011-02-01

These experiments were performed on a rat model. The rats were divided into eight groups and consequently exposed to either a saline solution (control), atropine or a combination of atropine and tabun. The reactivation efficacy of the oximes was estimated on the rats exposed to tabun, atropine and a reactivator of AChE. The oximes HI-6, obidoxime, trimedoxime, K203 and KR-22836 were used as representative compounds of commonly available and new AChE reactivators. Besides the positive effect of the administered reactivators on blood AChE activity, the sizable modulation of low molecular weight antioxidant (LMWA) levels was also determined. The LMWA levels in the the animals treated with the oxime reactivators were decreased in comparison with the animals treated by atropine alone. It was found that the levels of LMWA returned to the level found in the control animals when either trimedoxime, K203 or KR-22836 were administered. The principle of oxime reactivator function and a novel insight into AChE activity regulation and oxidative stress is discussed.

Principles of using Cold Atmospheric Plasma Stimulated Media for Cancer Treatment

PubMed Central

Yan, Dayun; Talbot, Annie; Nourmohammadi, Niki; Cheng, Xiaoqian; Canady, Jerome; Sherman, Jonathan; Keidar, Michael

2015-01-01

To date, the significant anti-cancer capacity of cold atmospheric plasma (CAP) on dozens of cancer cell lines has been demonstrated in vitro and in mice models. Conventionally, CAP was directly applied to irradiate cancer cells or tumor tissue. Over past three years, the CAP irradiated media was also found to kill cancer cells as effectively as the direct CAP treatment. As a novel strategy, using the CAP stimulated (CAPs) media has become a promising anti-cancer tool. In this study, we demonstrated several principles to optimize the anti-cancer capacity of the CAPs media on glioblastoma cells and breast cancer cells. Specifically, using larger wells on a multi-well plate, smaller gaps between the plasma source and the media, and smaller media volume enabled us to obtain a stronger anti-cancer CAPs media composition without increasing the treatment time. Furthermore, cysteine was the main target of effective reactive species in the CAPs media. Glioblastoma cells were more resistant to the CAPs media than breast cancer cells. Glioblastoma cells consumed the effective reactive species faster than breast cancer cells did. In contrast to nitric oxide, hydrogen peroxide was more likely to be the effective reactive species. PMID:26677750

Lithography-based fabrication of nanopore arrays in freestanding SiN and graphene membranes

NASA Astrophysics Data System (ADS)

Verschueren, Daniel V.; Yang, Wayne; Dekker, Cees

2018-04-01

We report a simple and scalable technique for the fabrication of nanopore arrays on freestanding SiN and graphene membranes based on electron-beam lithography and reactive ion etching. By controlling the dose of the single-shot electron-beam exposure, circular nanopores of any size down to 16 nm in diameter can be fabricated in both materials at high accuracy and precision. We demonstrate the sensing capabilities of these nanopores by translocating dsDNA through pores fabricated using this method, and find signal-to-noise characteristics on par with transmission-electron-microscope-drilled nanopores. This versatile lithography-based approach allows for the high-throughput manufacturing of nanopores and can in principle be used on any substrate, in particular membranes made out of transferable two-dimensional materials.

The Time-Temperature-Transformation (TTT) Diagram as a Basis for Relating the Formation and Properties of Reactive Coatings.

DTIC Science & Technology

1988-01-01

technique for characterizing reactive coatings. ’C. 2 INTRODUCTION This review of reserch in the author’s laboratory, which is set into a general context...obtained from the temperature depen- dence of the time to reach a specified viscosity approach the true activation energy for the chemical reactions...rate can be deduced in principle from the differences between the experimentally measured and the computed gelation and vitrification curves. The S

Comparative reactivity of mismatched and unpaired bases in relation to their type and surroundings. Chemical cleavage of DNA mismatches in mutation detection analysis.

PubMed

Yakubovskaya, Marianna G; Belyakova, Anna A; Gasanova, Viktoria K; Belitsky, Gennady A; Dolinnaya, Nina G

2010-07-01

Systematic study of chemical reactivity of non-Watson-Crick base pairs depending on their type and microenvironment was performed on a model system that represents two sets of synthetic DNA duplexes with all types of mismatched and unmatched bases flanked by T.A or G.C pairs. Using comparative cleavage pattern analysis, we identified the main and additional target bases and performed quantitative study of the time course and efficacy of DNA modification caused by potassium permanganate or hydroxylamine. Potassium permanganate in combination with tetraethylammonium chloride was shown to induce DNA cleavage at all mismatched or bulged T residues, as well as at thymines of neighboring canonical pairs. Other mispaired (bulged) bases and thymine residues located on the second position from the mismatch site were not the targets for KMnO(4) attack. In contrast, hydroxylamine cleaved only heteroduplexes containing mismatched or unmatched C residues, and did not modify adjacent cytosines. However when G.C pairs flank bulged C residue, neighboring cytosines are also attacked by hydroxylamine due to defect migration. Chemical reactivity of target bases was shown to correlate strongly with the local disturbance of DNA double helix at mismatch or bulge site. With our model system, we were able to prove the absence of false-negative and false-positive results. Portion of heteroduplex reliably revealed in a mixture with corresponding homoduplex consists of 5% for bulge bases and "open" non-canonical pairs, and 10% for wobble base pairs giving minimal violations in DNA structure. This study provides a complete understanding of the principles of mutation detection methodology based on chemical cleavage of mismatches and clarifies the advantages and limitations of this approach in various biological and conformational studies of DNA. Copyright 2010 Elsevier Masson SAS. All rights reserved.

An Analytical Model for Assessing Stability of Pre-Existing Faults in Caprock Caused by Fluid Injection and Extraction in a Reservoir

NASA Astrophysics Data System (ADS)

Wang, Lei; Bai, Bing; Li, Xiaochun; Liu, Mingze; Wu, Haiqing; Hu, Shaobin

2016-07-01

Induced seismicity and fault reactivation associated with fluid injection and depletion were reported in hydrocarbon, geothermal, and waste fluid injection fields worldwide. Here, we establish an analytical model to assess fault reactivation surrounding a reservoir during fluid injection and extraction that considers the stress concentrations at the fault tips and the effects of fault length. In this model, induced stress analysis in a full-space under the plane strain condition is implemented based on Eshelby's theory of inclusions in terms of a homogeneous, isotropic, and poroelastic medium. The stress intensity factor concept in linear elastic fracture mechanics is adopted as an instability criterion for pre-existing faults in surrounding rocks. To characterize the fault reactivation caused by fluid injection and extraction, we define a new index, the "fault reactivation factor" η, which can be interpreted as an index of fault stability in response to fluid pressure changes per unit within a reservoir resulting from injection or extraction. The critical fluid pressure change within a reservoir is also determined by the superposition principle using the in situ stress surrounding a fault. Our parameter sensitivity analyses show that the fault reactivation tendency is strongly sensitive to fault location, fault length, fault dip angle, and Poisson's ratio of the surrounding rock. Our case study demonstrates that the proposed model focuses on the mechanical behavior of the whole fault, unlike the conventional methodologies. The proposed method can be applied to engineering cases related to injection and depletion within a reservoir owing to its efficient computational codes implementation.

Cold Plasma Technology-principles and applications

USDA-ARS?s Scientific Manuscript database

Contamination of fresh and fresh-cut fruits and vegetables by foodborne pathogens has prompted research into novel interventions. Cold plasma is a nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes. This flexible sanitizing method uses ele...

The Rosiwal Principle and the regolithic distributions of solar-wind elements

NASA Technical Reports Server (NTRS)

Criswell, D. R.

1975-01-01

In situ accumulation of solar elements is studied for the purpose of determining the extent of applicability of the Rosiwal Principle. The Rosiwal Principle states that the grain exposure area is proportional to the fraction of the unit volume occupied by the grains, and the test involves measurement of the relative concentrations of inert gases and reactive elements across sets of lunar fines samples for which mean grain size, sorting, and minimum radius of surface correlation are known. In some cases, the quantity of an element implanted into the lunar fines from the solar wind is found to be surface correlated, and the implications of this relationship are considered. According to the Rosiwal Principle, coarse soils should retain less inert gas than fine soil. The Principle can also be applied to species volatized or sputtered from the lunar surface and redeposited locally.

Steepest-entropy-ascent quantum thermodynamic modeling of the relaxation process of isolated chemically reactive systems using density of states and the concept of hypoequilibrium state

NASA Astrophysics Data System (ADS)

Li, Guanchen; von Spakovsky, Michael R.

2016-01-01

This paper presents a study of the nonequilibrium relaxation process of chemically reactive systems using steepest-entropy-ascent quantum thermodynamics (SEAQT). The trajectory of the chemical reaction, i.e., the accessible intermediate states, is predicted and discussed. The prediction is made using a thermodynamic-ensemble approach, which does not require detailed information about the particle mechanics involved (e.g., the collision of particles). Instead, modeling the kinetics and dynamics of the relaxation process is based on the principle of steepest-entropy ascent (SEA) or maximum-entropy production, which suggests a constrained gradient dynamics in state space. The SEAQT framework is based on general definitions for energy and entropy and at least theoretically enables the prediction of the nonequilibrium relaxation of system state at all temporal and spatial scales. However, to make this not just theoretically but computationally possible, the concept of density of states is introduced to simplify the application of the relaxation model, which in effect extends the application of the SEAQT framework even to infinite energy eigenlevel systems. The energy eigenstructure of the reactive system considered here consists of an extremely large number of such levels (on the order of 10130) and yields to the quasicontinuous assumption. The principle of SEA results in a unique trajectory of system thermodynamic state evolution in Hilbert space in the nonequilibrium realm, even far from equilibrium. To describe this trajectory, the concepts of subsystem hypoequilibrium state and temperature are introduced and used to characterize each system-level, nonequilibrium state. This definition of temperature is fundamental rather than phenomenological and is a generalization of the temperature defined at stable equilibrium. In addition, to deal with the large number of energy eigenlevels, the equation of motion is formulated on the basis of the density of states and a set of associated degeneracies. Their significance for the nonequilibrium evolution of system state is discussed. For the application presented, the numerical method used is described and is based on the density of states, which is specifically developed to solve the SEAQT equation of motion. Results for different kinds of initial nonequilibrium conditions, i.e., those for gamma and Maxwellian distributions, are studied. The advantage of the concept of hypoequilibrium state in studying nonequilibrium trajectories is discussed.

Evidence to Support a Contribution of Polyreactive Antibodies to HLA Serum Reactivity.

PubMed

Gao, Baoshan; Rong, Chunshu; Porcheray, Fabrice; Moore, Carolina; Girouard, Timothy C; Saidman, Susan L; Wong, Waichi; Fu, Yaowen; Zorn, Emmanuel

2016-01-01

Assessing the serum reactivity to HLA is essential for the evaluation of transplant candidates and the follow-up of allograft recipients. In this study, we look for evidence at the clonal level that polyreactive antibodies cross-reactive to apoptotic cells and multiple autoantigens can also react to HLA and contribute to the overall serum reactivity. We immortalized B cell clones from the blood of 2 kidney transplant recipients and characterized their reactivity to self-antigens, apoptotic cells as well as native, denatured, and cryptic HLA determinants using enzyme-linked immunosorbent assay (ELISA), immunofluorescence, flow cytometry and Luminex assays. We also assessed the reactivity of 300 pretransplant serum specimens to HLA and apoptotic cells. We report here 4 distinct B cell clones cross-reactive to self and HLA class I. All 4 clones reacted to numerous HLA class I alleles but did not appear to target canonical "shared" epitopes. In parallel experiments, we observed a strong correlation between IgG reactivity to HLA and apoptotic cells in pretransplant serum samples collected from 300 kidney transplant recipients. Further analysis revealed that samples with higher reactivity to apoptotic cells displayed significantly higher class I percent panel-reactive antibodies compared to samples with low reactivity to apoptotic cells. We provide here (1) proof of principle at the clonal level that human polyreactive antibodies can cross-react to HLA, multiple self-antigens and apoptotic cells and (2) supportive evidence that polyreactive antibodies contribute to overall HLA reactivity in the serum of patients awaiting kidney transplant.

Conformational, vibrational and DFT studies of a newly synthesized arylpiperazine-based drug and evaluation of its reactivity towards the human GABA receptor

NASA Astrophysics Data System (ADS)

Onawole, A. T.; Al-Ahmadi, A. F.; Mary, Y. S.; Panicker, C. Y.; Ullah, N.; Armaković, S.; Armaković, S. J.; Van Alsenoy, C.; Al-Saadi, A. A.

2017-11-01

This study reports a computational assessment of important biochemical properties and vibrational assignments for the synthesized 1-(4-(3-methoxy-4-nitrophenyl)piperazin-1-yl)ethanone (MNPE). MNPE is related to the commonly used arylpiperazine-based drugs that exhibit a wide range of pharmacological activities. The characterization of MNPE is based on the readily sighted 1363 cm-1 infrared band (associated with piperazine ring stretching), 1308 cm-1 Raman line (associated with the phenyl ring breathing), 1242 cm-1 Raman line and 1092 cm-1 infrared band (both associated with Csbnd N stretching) as key modes in its vibrational spectra. First principle calculations revealed that MNPE could exist in sixteen different plausible conformations, which were used as basis to understand the possible molecular docking mechanism of the molecule as an agonist in the human GABAA receptor. The best binding scenarios showed the presence of intramolecular hydrogen bonding in MNPE and was comparable with the most stable configuration. It was further evaluated for its reactivity properties by utilizing the concepts of Average Local Ionization Energies (ALIE) and Fukui functions. The autoxidation and hydrolysis degradation likelihood of MNPE estimated from the computed bond dissociation energies and radial distribution functions predicted that MNPE is to be readily biodegradable in aqueous solutions.

Mutation analysis of the fusion domain region of St. Louis encephalitis virus envelope protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trainor, Nicole B.; Crill, Wayne D.; Roberson, Jill A.

2007-04-10

The immune response to flavivirus infections produces both species-specific and flavivirus cross-reactive antibodies. The presence of cross-reactive antibodies complicates serodiagnosis of flavivirus infections, especially secondary infections caused by a heterologous virus. A successful public health response to the growing global threat posed by flaviviruses necessitates the development of virus-specific diagnostic antigens. The flavivirus envelope (E) glycoprotein is the principle antigen stimulating protective immunity during infection. Using recombinant St. Louis encephalitis virus-like particles (VLPs), we have identified amino acid residues involved in flavivirus cross-reactive epitope determinants. Most significant among the residues studied are three highly conserved amino acids in the fusionmore » peptide: Gly104, Gly106, and Leu107. Substitutions of these residues dramatically influenced VLP secretion and cross-reactive monoclonal antibody reactivity. These results provide critical insight into the antigenic structure of the flaviviral E protein and toward development of species-specific diagnostic antigens that should improve both flavivirus diagnosis and estimates of disease burden.« less

Interplay of water and reactive elements in oxidation of alumina-forming alloys.

PubMed

Mortazavi, N; Geers, C; Esmaily, M; Babic, V; Sattari, M; Lindgren, K; Malmberg, P; Jönsson, B; Halvarsson, M; Svensson, J E; Panas, I; Johansson, L G

2018-06-11

High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable 'messy' nano-structured alumina layer to form. We propose that reactive-element-decorated, hydroxylated interfaces between alumina nanograins enable water to access an inner cathode in the bottom of the scale, at odds with the established scale growth scenario. As evidence, hydride-nanodomains and reactive element/hydrogen (deuterium) co-variation are observed in the alumina scale. The defect-rich alumina subsequently recrystallizes to form a protective scale. First-principles modelling is also performed to validate the RE effect. Our findings open up promising avenues in oxidation research and suggest ways to improve alloy properties.

Microstructure and wear resistance of Al2O3-M7C3/Fe composite coatings produced by laser controlled reactive synthesis

NASA Astrophysics Data System (ADS)

Tan, Hui; Luo, Zhen; Li, Yang; Yan, Fuyu; Duan, Rui

2015-05-01

Based on the principle of thermite reaction of Al and Fe2O3 powders, the Al2O3 ceramic reinforced Fe-based composite coatings were fabricated on a steel substrate by laser controlled reactive synthesis and cladding. The effects of different additions of thermite reactants on the phase transition, microstructure evolution, microhardness and wear resistance of the composite coatings were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers microhardness and block-on-ring wear test, respectively. The results show that Al2O3 ceramic and M7C3 carbide are in situ synthesized via the laser controlled reactive synthesis. The Al2O3 ceramic and M7C3 carbides prefer to distribute along the γ-Fe phase boundary continuously, which separates the γ-Fe matrix and is beneficial to the grain refinement. With the increase of thermite reactants, the amount of Al2O3 ceramic and M7C3 carbide in the composite coatings increases gradually. Moreover the cladding layer changes from dendritic structure to columnar structure and martensite structure in the heat affected zone becomes coarse. The increased thermite reactants improve the microhardness and wear resistance of the in situ composite coatings obviously and enhance the hardness of the heat affected zone, which should be ascribed to the grain refinement, ceramic and carbide precipitation and solid solution strengthening.

Method and apparatus for measuring the state of charge in a battery based on volume of battery components

DOEpatents

Rouhani, S. Zia

1996-10-22

The state of charge of electrochemical batteries of different kinds is determined by measuring the incremental change in the total volume of the reactive masses in the battery. The invention is based on the principle that all electrochemical batteries, either primary or secondary (rechargeable), produce electricity through a chemical reaction with at least one electrode, and the chemical reactions produce certain changes in the composition and density of the electrode. The reactive masses of the electrodes, the electrolyte, and any separator or spacers are usually contained inside a battery casing of a certain volume. As the battery is used, or recharged, the specific volume of at least one of the electrode masses will change and, since the masses of the materials do not change considerably, the total volume occupied by at least one of the electrodes will change. These volume changes may be measured in many different ways and related to the state of charge in the battery. In one embodiment, the volume change can be measured by monitoring the small changes in one of the principal dimensions of the battery casing as it expands or shrinks to accommodate the combined volumes of its components.

Active cleaning technique device

NASA Technical Reports Server (NTRS)

Shannon, R. L.; Gillette, R. B.

1973-01-01

The objective of this program was to develop a laboratory demonstration model of an active cleaning technique (ACT) device. The principle of this device is based primarily on the technique for removing contaminants from optical surfaces. This active cleaning technique involves exposing contaminated surfaces to a plasma containing atomic oxygen or combinations of other reactive gases. The ACT device laboratory demonstration model incorporates, in addition to plasma cleaning, the means to operate the device as an ion source for sputtering experiments. The overall ACT device includes a plasma generation tube, an ion accelerator, a gas supply system, a RF power supply and a high voltage dc power supply.

The Antitumor Effect of Singlet Oxygen.

PubMed

Bauer, Georg

2016-11-01

Tumor cells are protected against intercellular apoptosis-inducing signaling through expression of membrane-associated catalase and superoxide dismutase. Exogenous singlet oxygen derived from activated photosensitizers or from cold atmospheric plasma causes local inactivation of protective catalase which is followed by the generation of secondary extracellular singlet oxygen. This process is specific for tumor cells and is driven by a complex interaction between H 2 O 2 and peroxynitrite. Secondary singlet oxygen has the potential for autoamplification of its generation, resulting in optimal inactivation of protective catalase and reactivation of intercellular apoptosis-inducing signaling. An increase in the endogenous NO concentration also causes inactivation of catalase and autoamplificatory generation of secondary singlet oxygen. This principle is essential for the antitumor activity of secondary plant products, such as cyanidins and other inhibitors of NO dioxygenase. It seems that the action of the established chemotherapeutic taxol and the recently established antitumor effect of certain azoles are based on the same principles. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

A STUDY OF THE INDIGOGENIC PRINCIPLE AND IN VITRO MACROPHAGE DIFFERENTIATION

DTIC Science & Technology

and beta- glucuronidase activities. Moreover, there was a progressive increase in the densities of enzyme reactive centers. Indigo reaction product was...not observed over nuclei; lipid droplets and cell background were free from spurious precipitations. Both galactosidase and glucuronidase were

Progress report on the k{sub infinity} measurements of HTGR type lattices with the oscillation technique at zero reactivity; Rapport d'advancement sur les mesures de K {sub infinite} des reseaux du type HTGR avec la technique de l'oscillateur a'reactivite' nulle (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1971-01-15

The principles of measuring k {sub infinity} for a HTGR lattice using the oscillation technique with zero reactivity were already presented at the ''9th reactor physics meeting of countries participating in the Dragon project''. A brief summary of the essential characteristics of the experiment is followed by a status report on present work.

Light-sensitive Lipid-based Nanoparticles for Drug Delivery: Design Principles and Future Considerations for Biological Applications

PubMed Central

Yavlovich, Amichai; Smith, Brandon; Gupta, Kshitij; Blumenthal, Robert; Puri, Anu

2011-01-01

Radiation-based therapies aided by nanoparticles have been developed since decades, and can be primarily categorized into two main platforms. First, delivery of payload of photo-reactive drugs (photosensitizers) using the conventional nanoparticles, and second, design and development of photo-triggerable nanoparticles (primarily liposomes) to attain light-assisted on-demand drug delivery. The main focus of this review is to provide an update of the history, current status and future applications of photo-triggerable lipid-based nanoparticles (light-sensitive liposomes). We will begin with a brief overview on the applications of liposomes for delivery of photosensitizers, including the choice of photosensitizers for photodynamic therapy, as well as the currently available light sources (lasers) used for these applications. The main segment of this review will encompass the details on the strategies to develop photo-triggerable designer liposomes for their drug delivery function. The principles underlying the assembly of photoreactive lipids into nanoparticles (liposomes) and photo-triggering mechanisms will be presented. We will also discuss factors that limit the applications of these liposomes for in vivo triggered drug delivery and emerging concepts that may lead to the biologically viable photo-activation strategies. We will conclude with our view point on the future perspectives of light-sensitive liposomes in the clinic. PMID:20939770

Development of a glucose sensor employing quick and easy modification method with mediator for altering electron acceptor preference.

PubMed

Hatada, Mika; Loew, Noya; Inose-Takahashi, Yuka; Okuda-Shimazaki, Junko; Tsugawa, Wakako; Mulchandani, Ashok; Sode, Koji

2018-06-01

Enzyme based electrochemical biosensors are divided into three generations according to their type of electron transfer from the cofactors of the enzymes to the electrodes. Although the 3rd generation sensors using direct electron transfer (DET) type enzymes are ideal, the number of enzyme types which possess DET ability is limited. In this study, we report of a glucose sensor using mediator-modified glucose dehydrogenase (GDH), that was fabricated by a new quick-and-easy method using the pre-functionalized amine reactive phenazine ethosulfate (arPES). Thus mediator-modified GDH obtained the ability to transfer electrons to bulky electron acceptors as well as electrodes. The concentration of glucose was successfully measured using electrodes with immobilized PES-modified GDH, without addition of external electron mediators. Therefore, continuous monitoring systems can be developed based on this "2.5th generation" electron transfer principle utilizing quasi-DET. Furthermore, we successfully modified two other diagnostically relevant enzymes, glucoside 3-dehydrogenase and lactate oxidase, with PES. Therefore, various kinds of diagnostic enzymes can achieve quasi-DET ability simply by modification with arPES, suggesting that continuous monitoring systems based on the 2.5th generation principle can be developed for various target molecules. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced carbon monoxide sensing properties of TiO2 with exposed (0 0 1) facet: A combined first-principle and experimental study

NASA Astrophysics Data System (ADS)

Zhang, Yuxuan; Zeng, Wen; Ye, Hong; Li, Yanqiong

2018-06-01

In the present study, crystal-facet-dependent gas sensing performance was thoroughly investigated and sensing mechanism of TiO2 was elaborated in depth. Anatase TiO2 nano-polyhedron with highly reactive (0 0 1) facet was successfully synthesized via a one-pot hydrothermal method using fluoride as facet stabilizer and was utilized for fabrication of carbon monoxide gas sensors, followed by characterization of microstructure, phase-purity and gas-sensing properties. Chemiresistive properties of (0 0 1)-dominated gas sensor exhibit superior response to CO with a maximum response of 27.9 at 300 ppm in optimum working temperature as 350 °C. Particularly, first-principle calculation was carried out to expound the sensing mechanism, which shows that CO adsorption on (0 0 1) facet is more stable and favorable than that on normally exposed (1 0 1) facet, corroborating the reactive nature of (0 0 1) facet.

Insights into geometries, stabilities, electronic structures, reactivity descriptors, and magnetic properties of bimetallic Nim Cun-m (m = 1, 2; n = 3-13) clusters: Comparison with pure copper clusters.

PubMed

Singh, Raman K; Iwasa, Takeshi; Taketsugu, Tetsuya

2018-05-25

A long-range corrected density functional theory (LC-DFT) was applied to study the geometric structures, relative stabilities, electronic structures, reactivity descriptors and magnetic properties of the bimetallic NiCu n -1 and Ni 2 Cu n -2 (n = 3-13) clusters, obtained by doping one or two Ni atoms to the lowest energy structures of Cu n , followed by geometry optimizations. The optimized geometries revealed that the lowest energy structures of the NiCu n -1 and Ni 2 Cu n -2 clusters favor the Ni atom(s) situated at the most highly coordinated position of the host copper clusters. The averaged binding energy, the fragmentation energies and the second-order energy differences signified that the Ni doped clusters can continue to gain an energy during the growth process. The electronic structures revealed that the highest occupied molecular orbital and the lowest unoccupied molecular orbital energies of the LC-DFT are reliable and can be used to predict the vertical ionization potential and the vertical electron affinity of the systems. The reactivity descriptors such as the chemical potential, chemical hardness and electrophilic power, and the reactivity principle such as the minimum polarizability principle are operative for characterizing and rationalizing the electronic structures of these clusters. Moreover, doping of Ni atoms into the copper clusters carry most of the total spin magnetic moment. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Evidence to support a contribution of polyreactive antibodies to HLA serum reactivity

PubMed Central

Gao, Baoshan; Rong, Chunshu; Porcheray, Fabrice; Moore, Carolina; Girouard, Timothy C.; Saidman, Susan L.; Wong, Waichi; Fu, Yaowen; Zorn, Emmanuel

2015-01-01

Background Assessing the serum reactivity to HLA is essential for the evaluation of transplant candidates and the follow-up of allograft recipients. In this study, we look for evidence at the clonal level that polyreactive antibodies cross-reactive to apoptotic cells and multiple autoantigens can also react to HLA and contribute to the overall serum reactivity. Methods We immortalized B cell clones from the blood of two kidney transplant recipients and characterized their reactivity to self-antigens, apoptotic cells as well as native, denatured and cryptic HLA determinants using ELISA, immunofluorescence, flow cytometry and Luminex assays. We also assessed the reactivity of 300 pre-transplant serum specimens to HLA and apoptotic cells. Results We report here 4 distinct B cell clones cross-reactive to self and HLA class I. All 4 clones reacted to numerous HLA class I alleles but did not appear to target canonical “shared” epitopes. In parallel experiments, we observed a strong correlation between IgG reactivity to HLA and apoptotic cells in pre-transplant serum samples collected from 300 kidney transplant recipients. Further analysis revealed that samples with higher reactivity to apoptotic cells displayed significantly higher class I percent PRA compared to samples with low reactivity to apoptotic cells. Conclusions We provide here 1) proof of principle at the clonal level that human polyreactive antibodies can cross-react to HLA, multiple self-antigens and apoptotic cells and 2) supportive evidence that polyreactive antibodies contribute to overall HLA reactivity in the serum of patients awaiting kidney transplant. PMID:26285015

A transaction assessment method for allocation of transmission services

NASA Astrophysics Data System (ADS)

Banunarayanan, Venkatasubramaniam

The purpose of this research is to develop transaction assessment methods for allocating transmission services that are provided by an area/utility to power transactions. Transmission services are the services needed to deliver, or provide the capacity to deliver, real and reactive power from one or more supply points to one or more delivery points. As the number of transactions increase rapidly in the emerging deregulated environment, accurate quantification of the transmission services an area/utility provides to accommodate a transaction is becoming important, because then appropriate pricing schemes can be developed to compensate for the parties that provide these services. The Allocation methods developed are based on the "Fair Resource Allocation Principle" and they determine for each transaction the following: the flowpath of the transaction (both real and reactive power components), generator reactive power support from each area/utility, real power loss support from each area/utility. Further, allocation methods for distributing the cost of relieving congestion on transmission lines caused by transactions are also developed. The main feature of the proposed methods is representation of actual usage of the transmission services by the transactions. The proposed method is tested extensively on a variety of systems. The allocation methods developed in this thesis for allocation of transmission services to transactions is not only useful in studying the impact of transactions on a transmission system in a multi-transaction case, but they are indeed necessary to meet the criteria set forth by FERC with regard to pricing based on actual usage. The "consistency" of the proposed allocation methods has also been investigated and tested.

Adsorption of CO and O2 molecules on Li metal adsorbed graphene: Search for graphene based gas sensors

NASA Astrophysics Data System (ADS)

Kaur, Gagandeep; Gupta, Shuchi; Sachdeva, Ritika; Dharamvir, Keya

2018-05-01

Adsorption of small gas molecules (such as CO and O2) on pristine graphene (PG) and Li-adsorbed graphene (PG-Li) have been investigated using first principles methods within density functional theory (DFT). We also notice that PG-Li has a higher chemical reactivity towards the gas molecules as compared to PG and these molecules have higher adsorption energy on this surface. Moreover, the strong interactions between PG-Li and the adsorbed molecules (as compared to PG and gas molecules) induce dramatic changes to the electronic properties of PG adsorbed with Li and make PG-Li a promising candidate as sensing material for CO and O2 gases.

A Closer Examination of the Structured Written Disclosure Procedure.

ERIC Educational Resources Information Center

Sloan, Denise M.; Marx, Brian P.

2004-01-01

The current study examined psychological and physical health outcomes of the written disclosure paradigm and the hypothesis that the principles of therapeutic exposure account for the beneficial effects of the paradigm. Participants were randomly assigned to either a written disclosure condition or a control condition. Reactivity to the writing…

Caging and Photoactivation in Single-Molecule Förster Resonance Energy Transfer Experiments

PubMed Central

2017-01-01

Caged organic fluorophores are established tools for localization-based super-resolution imaging. Their use relies on reversible deactivation of standard organic fluorophores by chemical reduction or commercially available caged dyes with ON switching of the fluorescent signal by ultraviolet (UV) light. Here, we establish caging of cyanine fluorophores and caged rhodamine dyes, i.e., chemical deactivation of fluorescence, for single-molecule Förster resonance energy transfer (smFRET) experiments with freely diffusing molecules. They allow temporal separation and sorting of multiple intramolecular donor–acceptor pairs during solution-based smFRET. We use this “caged FRET” methodology for the study of complex biochemical species such as multisubunit proteins or nucleic acids containing more than two fluorescent labels. Proof-of-principle experiments and a characterization of the uncaging process in the confocal volume are presented. These reveal that chemical caging and UV reactivation allow temporal uncoupling of convoluted fluorescence signals from, e.g., multiple spectrally similar donor or acceptor molecules on nucleic acids. We also use caging without UV reactivation to remove unwanted overlabeled species in experiments with the homotrimeric membrane transporter BetP. We finally outline further possible applications of the caged FRET methodology, such as the study of weak biochemical interactions, which are otherwise impossible with diffusion-based smFRET techniques because of the required low concentrations of fluorescently labeled biomolecules. PMID:28362086

Mars surface chemistry investigated with the MOx probe: A 1-kg optical microsensor-based chemical analysis instrument

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ricco, A.J.; Butler, M.A.; Grunthaner, F.J.

The authors have designed and built the prototype of an instrument that will use fiber optic micromirror-based chemical sensors to investigate the surprising reactivity of martian soil reported by several Viking Lander Experiments in the mid 1970s. The MOx (Mars Oxidant Experiment) Instrument, which will probe the reactivity of the near-surface martian atmosphere as well as soil, utilizes an array of chemically sensitive thin films including metals, organometallics, and organic dyes to produce a pattern of reflectivity changes characteristic of the species interacting with these sensing layers. The 850-g system includes LED light sources, optical fiber light guides, silicon micromachinedmore » fixtures, a line-array CCD detector, control-and-measurement electronics, microprocessor, memory, interface, batteries, and housing. This instrument monitors real-time reflectivities from an array of {approximately}200 separate micromirrors. The unmanned Russian Mars 96 mission is slated to carry the MOx Instrument along with experiments from several other nations. The principles of the chemically sensitive micromirror upon which this instrument is based will be described and preliminary data for reactions of micromirrors with oxidant materials believed to be similar to those on Mars will be presented. The general design of the instrument, including Si micromachined components, as well as the range of coatings and the rationale for their selection, will be discussed as well.« less

Design principles for electrolytes and interfaces for stable lithium-metal batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tikekar, Mukul D.; Choudhury, Snehashis; Tu, Zhengyuan

2016-09-08

The future of electrochemical energy storage hinges on the advancement of science and technology that enables rechargeable batteries that utilize reactive metals as anodes. With specific capacity more than ten times that of the LiC6 anode used in present-day lithium-ion batteries, cells based on Li-metal anodes are of particular interest. Effective strategies for stabilizing the anode in such cells are now understood to be a requirement for progress on exceptional storage technologies, including Li–S and Li–O2 batteries. Multiple challenges—parasitic reactions of Li-metal with liquid electrolytes, unstable and dendritic electrodeposition, and dendrite-induced short circuits—derailed early efforts to commercialize such lithium-metal batteries.more » Here we consider approaches for rationally designing electrolytes and Li-metal/electrolyte interfaces for stable, dendrite-free operation of lithium-metal batteries. On the basis of fundamental understanding of the failure modes of reactive metal anodes, we discuss the key variables that govern the stability of electrodeposition at the Li anode and propose a universal framework for designing stable electrolytes and interfaces for lithium-metal batteries.« less

Design principles for electrolytes and interfaces for stable lithium-metal batteries

NASA Astrophysics Data System (ADS)

Tikekar, Mukul D.; Choudhury, Snehashis; Tu, Zhengyuan; Archer, Lynden A.

2016-09-01

The future of electrochemical energy storage hinges on the advancement of science and technology that enables rechargeable batteries that utilize reactive metals as anodes. With specific capacity more than ten times that of the LiC6 anode used in present-day lithium-ion batteries, cells based on Li-metal anodes are of particular interest. Effective strategies for stabilizing the anode in such cells are now understood to be a requirement for progress on exceptional storage technologies, including Li-S and Li-O2 batteries. Multiple challenges—parasitic reactions of Li-metal with liquid electrolytes, unstable and dendritic electrodeposition, and dendrite-induced short circuits—derailed early efforts to commercialize such lithium-metal batteries. Here we consider approaches for rationally designing electrolytes and Li-metal/electrolyte interfaces for stable, dendrite-free operation of lithium-metal batteries. On the basis of fundamental understanding of the failure modes of reactive metal anodes, we discuss the key variables that govern the stability of electrodeposition at the Li anode and propose a universal framework for designing stable electrolytes and interfaces for lithium-metal batteries.

Comparative Analysis of Serum (Anti)oxidative Status Parameters in Healthy Persons

PubMed Central

Jansen, Eugène HJM; Ruskovska, Tatjana

2013-01-01

Five antioxidant and two oxidative stress assays were applied to serum samples of 43 healthy males. The antioxidant tests showed different inter-assay correlations. A very good correlation of 0.807 was observed between the ferric reducing ability of plasma (FRAP) and total antioxidant status (TAS) assay and also a fair correlation of 0.501 between the biological antioxidant potential (BAP) and TAS assay. There was no statistically significant correlation between the BAP and FRAP assay. The anti-oxidant assays have a high correlation with uric acid, especially the TAS (0.922) and FRAP assay (0.869). The BAP assay has a much lower and no statistically significant correlation with uric acid (0.302), which makes BAP more suitable for the antioxidant status. The total thiol assay showed no statistically significant correlation with uric acid (0.114). The total thiol assay, which is based on a completely different principle, showed a good and statistically significant correlation with the BAP assay (0.510) and also to the TAS assay, but to a lower and not significant extent (0.279) and not with the FRAP assay (−0.008). The oxy-adsorbent test (OXY) assay has no correlation with any of the other assays tested. The oxidative stress assays, reactive oxygen metabolites (ROM) and total oxidant status (TOS), based on a different principle, do not show a statistically significant correlation with the serum samples in this study. Both assays showed a negative, but not significant, correlation with the antioxidant assays. In conclusion, the ROM, TOS, BAP and TTP assays are based on different principles and will have an additional value when a combination of these assays will be applied in large-scale population studies. PMID:23507749

Scaling laws and reduced-order models for mixing and reactive-transport in heterogeneous anisotropic porous media

NASA Astrophysics Data System (ADS)

Mudunuru, M. K.; Karra, S.; Nakshatrala, K. B.

2016-12-01

Fundamental to enhancement and control of the macroscopic spreading, mixing, and dilution of solute plumes in porous media structures is the topology of flow field and underlying heterogeneity and anisotropy contrast of porous media. Traditionally, in literature, the main focus was limited to the shearing effects of flow field (i.e., flow has zero helical density, meaning that flow is always perpendicular to vorticity vector) on scalar mixing [2]. However, the combined effect of anisotropy of the porous media and the helical structure (or chaotic nature) of the flow field on the species reactive-transport and mixing has been rarely studied. Recently, it has been experimentally shown that there is an irrefutable evidence that chaotic advection and helical flows are inherent in porous media flows [1,2]. In this poster presentation, we present a non-intrusive physics-based model-order reduction framework to quantify the effects of species mixing in-terms of reduced-order models (ROMs) and scaling laws. The ROM framework is constructed based on the recent advancements in non-negative formulations for reactive-transport in heterogeneous anisotropic porous media [3] and non-intrusive ROM methods [4]. The objective is to generate computationally efficient and accurate ROMs for species mixing for different values of input data and reactive-transport model parameters. This is achieved by using multiple ROMs, which is a way to determine the robustness of the proposed framework. Sensitivity analysis is performed to identify the important parameters. Representative numerical examples from reactive-transport are presented to illustrate the importance of the proposed ROMs to accurately describe mixing process in porous media. [1] Lester, Metcalfe, and Trefry, "Is chaotic advection inherent to porous media flow?," PRL, 2013. [2] Ye, Chiogna, Cirpka, Grathwohl, and Rolle, "Experimental evidence of helical flow in porous media," PRL, 2015. [3] Mudunuru, and Nakshatrala, "On enforcing maximum principles and achieving element-wise species balance for advection-diffusion-reaction equations under the finite element method," JCP, 2016. [4] Quarteroni, Manzoni, and Negri. "Reduced Basis Methods for Partial Differential Equations: An Introduction," Springer, 2016.

Surface chemistry of copper metal and copper oxide atomic layer deposition from copper(ii) acetylacetonate: a combined first-principles and reactive molecular dynamics study.

PubMed

Hu, Xiao; Schuster, Jörg; Schulz, Stefan E; Gessner, Thomas

2015-10-28

Atomistic mechanisms for the atomic layer deposition using the Cu(acac)2 (acac = acetylacetonate) precursor are studied using first-principles calculations and reactive molecular dynamics simulations. The results show that Cu(acac)2 chemisorbs on the hollow site of the Cu(110) surface and decomposes easily into a Cu atom and the acac-ligands. A sequential dissociation and reduction of the Cu precursor [Cu(acac)2 → Cu(acac) → Cu] are observed. Further decomposition of the acac-ligand is unfavorable on the Cu surface. Thus additional adsorption of the precursors may be blocked by adsorbed ligands. Molecular hydrogen is found to be nonreactive towards Cu(acac)2 on Cu(110), whereas individual H atoms easily lead to bond breaking in the Cu precursor upon impact, and thus release the surface ligands into the gas-phase. On the other hand, water reacts with Cu(acac)2 on a Cu2O substrate through a ligand-exchange reaction, which produces gaseous H(acac) and surface OH species. Combustion reactions with the main by-products CO2 and H2O are observed during the reaction between Cu(acac)2 and ozone on the CuO surface. The reactivity of different co-reactants toward Cu(acac)2 follows the order H > O3 > H2O.

The development of the super-biodiesel production continuously from Sunan pecan oil through the process of reactive distillation

NASA Astrophysics Data System (ADS)

Yohana, Eflita; Yulianto, Moh. Endy; Ikhsan, Diyono; Nanta, Aditya Marga; Puspitasari, Ristiyanti

2016-06-01

In general, a vegetable oil-based biodiesel production commercially operates a batch process with high investments and operational costs. Thus, it is necessary to develop super-biodiesel production from sunan pecan oil continuously through the process of reactive distillation. There are four advantages of the reactive distillation process for the biodiesel production, as follows: (i) it incorporates the process of transesterification reaction, and product separation of residual reactants become one stage of the process, so it saves the investment and operation costs, (ii) it reduces the need for raw materials because the methanol needed corresponds to the stoichiometry, so it also reduces the operation costs, (iii) the holdup time in the column is relatively short (5±0,5 minutes) compared to the batch process (1-2 hours), so it will reduce the operational production costs, and (iv) it is able to shift the reaction equilibrium, because the products and reactants that do not react are instantly separated (based on Le Chatelier's principles) so the conversion will be increased. However, the very crucial problem is determining the design tools and process conditions in order to maximize the conversion of the transesterification reaction in both phases. Thus, the purpose of this research was to design a continuous reactive distillation process by using a recycled condensate to increase the productivity of the super-biodiesel from sunan pecan oil. The research was carried out in three stages including (i) designing and fabricating the reactive distillation equipment, (ii) testing the tool performance and the optimization of the biodiesel production, and (iii) biodiesel testing on the diesel engine. These three stages were needed in designing and scaling-up the process tools and the process operation commercially. The reactive distillation process tools were designed and manufactured with reference to the design system tower by Kitzer, et.al. (2008). The manufactured reactive distillation consisted of packing distillation columns equipped with a reboiler and condenser, with the prototype made of stainless steel material equipped with sigh glass. The filling column expands the contact of liquid-vapor phase so that the two reactants between methanol and oil would be converted into methyl ester and glycerol. The initial results of the study indicated that the relatively good condition is reached at the peak temperature and the base of the column of 62°C and 71°C with NaOH 2% of methanol weight as the catalyst at the feed ratio of methanol and the sunan pecan oil 4:1. The result of the performance test of the diesel engine indicated that the efficiency of the biodiesel fuel was achieved relatively good at 1.7% with 2500 rpm engine speed.

Facet-dependent photocatalytic properties of TiO(2) -based composites for energy conversion and environmental remediation.

PubMed

Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman

2014-03-01

Titanium dioxide (TiO2 ) is one of the most widely investigated metal oxides because of its extraordinary surface, electronic, and photocatalytic properties. However, the large band gap of TiO2 and the considerable recombination of photogenerated electron-hole pairs limit its photocatalytic efficiency. Therefore, research attention is being increasingly directed towards engineering the surface structure of TiO2 on the atomic level (namely morphological control of {001} facets on the micro- and nanoscale) to fine-tune its physicochemical properties; this could ultimately lead to the optimization of selectivity and reactivity. This Review encompasses the fundamental principles to enhance the photocatalytic activity by using highly reactive {001}-faceted TiO2 -based composites. The current progress of such composites, with particular emphasis on the photodegradation of pollutants and photocatalytic water splitting for hydrogen generation, is also discussed. The progresses made are thoroughly examined for achieving remarkable photocatalytic performances, with additional insights with regard to charge transfer. Finally, a summary and some perspectives on the challenges and new research directions for future exploitation in this emerging frontier are provided, which hopefully would allow for harnessing the outstanding structural and electronic properties of {001} facets for various energy- and environmental-related applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal decomposition of condensed-phase nitromethane from molecular dynamics from ReaxFF reactive dynamics.

PubMed

Han, Si-ping; van Duin, Adri C T; Goddard, William A; Strachan, Alejandro

2011-05-26

We studied the thermal decomposition and subsequent reaction of the energetic material nitromethane (CH(3)NO(2)) using molecular dynamics with ReaxFF, a first principles-based reactive force field. We characterize the chemistry of liquid and solid nitromethane at high temperatures (2000-3000 K) and density 1.97 g/cm(3) for times up to 200 ps. At T = 3000 K the first reaction in the decomposition of nitromethane is an intermolecular proton transfer leading to CH(3)NOOH and CH(2)NO(2). For lower temperatures (T = 2500 and 2000 K) the first reaction during decomposition is often an isomerization reaction involving the scission of the C-N bond the formation of a C-O bond to form methyl nitrate (CH(3)ONO). Also at very early times we observe intramolecular proton transfer events. The main product of these reactions is H(2)O which starts forming following those initiation steps. The appearance of H(2)O marks the beginning of the exothermic chemistry. Recent quantum-mechanics-based molecular dynamics simulations on the chemical reactions and time scales for decomposition of a crystalline sample heated to T = 3000 K for a few picoseconds are in excellent agreement with our results, providing an important, direct validation of ReaxFF.

Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Robert C.; Szecsody, James; Rigali, Mark J.

We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests tomore » study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.« less

Direct optical sensors: principles and selected applications.

PubMed

Gauglitz, Guenter

2005-01-01

In the field of bio and chemosensors a large number of detection principles has been published within the last decade. These detection principles are based either on the observation of fluorescence-labelled systems or on direct optical detection in the heterogeneous phase. Direct optical detection can be measured by remission (absorption of reflected radiation, opt(r)odes), by measuring micro-refractivity, or measuring interference. In the last case either Mach-Zehnder interferometers or measurement of changes in the physical thickness of the layer (measuring micro-reflectivity) caused, e.g., by swelling effects in polymers (due to interaction with analytes) or in bioassays (due to affinity reactions) also play an important role. Here, an overview of methods of microrefractometric and microreflectometric principles is given and benefits and drawbacks of the various approaches are demonstrated using samples from the chemo and biosensor field. The quality of sensors does not just depend on transduction principles but on the total sensor system defined by this transduction, the sensitive layer, data acquisition electronics, and evaluation software. The intention of this article is, therefore, to demonstrate the essentials of the interaction of these parts within the system, and the focus is on optical sensing using planar transducers, because fibre optical sensors have been reviewed in this journal only recently. Lack of selectivity of chemosensors can be compensated either by the use of sensor arrays or by evaluating time-resolved measurements of analyte/sensitive layer interaction. In both cases chemometrics enables the quantification of analyte mixtures. These data-processing methods have also been successfully applied to antibody/antigen interactions even using cross-reactive antibodies. Because miniaturisation and parallelisation are essential approaches in recent years, some aspects and current trends, especially for bio-applications, will be discussed. Miniaturisation is especially well covered in the literature.

Reduction of Cross-Reactive Carbohydrate Determinants in Plant Foodstuff: Elucidation of Clinical Relevance and Implications for Allergy Diagnosis

PubMed Central

Brehler, Randolf; von Schaewen, Antje

2011-01-01

Background A longstanding debate in allergy is whether or not specific immunoglobulin-E antibodies (sIgE), recognizing cross-reactive carbohydrate determinants (CCD), are able to elicit clinical symptoms. In pollen and food allergy, ≥20% of patients display in-vitro CCD reactivity based on presence of α1,3-fucose and/or β1,2-xylose residues on N-glycans of plant (xylose/fucose) and insect (fucose) glycoproteins. Because the allergenicity of tomato glycoallergen Lyc e 2 was ascribed to N-glycan chains alone, this study aimed at evaluating clinical relevance of CCD-reduced foodstuff in patients with carbohydrate-specific IgE (CCD-sIgE). Methodology/Principal Findings Tomato and/or potato plants with stable reduction of Lyc e 2 (tomato) or CCD formation in general were obtained via RNA interference, and gene-silencing was confirmed by immunoblot analyses. Two different CCD-positive patient groups were compared: one with tomato and/or potato food allergy and another with hymenoptera-venom allergy (the latter to distinguish between CCD- and peptide-specific reactions in the food-allergic group). Non-allergic and CCD-negative food-allergic patients served as controls for immunoblot, basophil activation, and ImmunoCAP analyses. Basophil activation tests (BAT) revealed that Lyc e 2 is no key player among other tomato (glyco)allergens. CCD-positive patients showed decreased (re)activity with CCD-reduced foodstuff, most obvious in the hymenoptera venom-allergic but less in the food-allergic group, suggesting that in-vivo reactivity is primarily based on peptide- and not CCD-sIgE. Peptide epitopes remained unaffected in CCD-reduced plants, because CCD-negative patient sera showed reactivity similar to wild-type. In-house-made ImmunoCAPs, applied to investigate feasibility in routine diagnosis, confirmed BAT results at the sIgE level. Conclusions/Significance CCD-positive hymenoptera venom-allergic patients (control group) showed basophil activation despite no allergic symptoms towards tomato and potato. Therefore, this proof-of-principle study demonstrates feasibility of CCD-reduced foodstuff to minimize ‘false-positive results’ in routine serum tests. Despite confirming low clinical relevance of CCD antibodies, we identified one patient with ambiguous in-vitro results, indicating need for further component-resolved diagnosis. PMID:21423762

Force-induced chemical reactions on the metal centre in a single metalloprotein molecule.

PubMed

Zheng, Peng; Arantes, Guilherme M; Field, Martin J; Li, Hongbin

2015-06-25

Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.

Force-induced chemical reactions on the metal centre in a single metalloprotein molecule

PubMed Central

Zheng, Peng; Arantes, Guilherme M.; Field, Martin J.; Li, Hongbin

2015-01-01

Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions. PMID:26108369

An improved AVC strategy applied in distributed wind power system

NASA Astrophysics Data System (ADS)

Zhao, Y. N.; Liu, Q. H.; Song, S. Y.; Mao, W.

2016-08-01

Traditional AVC strategy is mainly used in wind farm and only concerns about grid connection point, which is not suitable for distributed wind power system. Therefore, this paper comes up with an improved AVC strategy applied in distributed wind power system. The strategy takes all nodes of distribution network into consideration and chooses the node having the most serious voltage deviation as control point to calculate the reactive power reference. In addition, distribution principles can be divided into two conditions: when wind generators access to network on single node, the reactive power reference is distributed according to reactive power capacity; when wind generators access to network on multi-node, the reference is distributed according to sensitivity. Simulation results show the correctness and reliability of the strategy. Compared with traditional control strategy, the strategy described in this paper can make full use of generators reactive power output ability according to the distribution network voltage condition and improve the distribution network voltage level effectively.

Platinum adlayered ruthenium nanoparticles, method for preparing, and uses thereof

DOEpatents

Tong, YuYe; Du, Bingchen

2015-08-11

A superior, industrially scalable one-pot ethylene glycol-based wet chemistry method to prepare platinum-adlayered ruthenium nanoparticles has been developed that offers an exquisite control of the platinum packing density of the adlayers and effectively prevents sintering of the nanoparticles during the deposition process. The wet chemistry based method for the controlled deposition of submonolayer platinum is advantageous in terms of processing and maximizing the use of platinum and can, in principle, be scaled up straightforwardly to an industrial level. The reactivity of the Pt(31)-Ru sample was about 150% higher than that of the industrial benchmark PtRu (1:1) alloy sample but with 3.5 times less platinum loading. Using the Pt(31)-Ru nanoparticles would lower the electrode material cost compared to using the industrial benchmark alloy nanoparticles for direct methanol fuel cell applications.

Effect of capillary forces on the nonstationary fall of a drop in an infinite fluid

NASA Astrophysics Data System (ADS)

Antanovskii, L. K.

1991-12-01

An explicit solution is presented for the linear problem concerning the motion of a drop in an infinite fluid in the presence of any number of surfactants (chemical reactions are not considered in the first approximation). It is shown that the behavior of the system considered is consistent with the Le Chatelier principle. The reactivity of the capillary forces is directly related to the fundamental principles of thermodynamics, which makes it possible to write equations of surfactant thermodiffusion in symmetric form and obtain a relatively simple solution to the linearized problem.

Relations among several nuclear and electronic density functional reactivity indexes

NASA Astrophysics Data System (ADS)

Torrent-Sucarrat, Miquel; Luis, Josep M.; Duran, Miquel; Toro-Labbé, Alejandro; Solà, Miquel

2003-11-01

An expansion of the energy functional in terms of the total number of electrons and the normal coordinates within the canonical ensemble is presented. A comparison of this expansion with the expansion of the energy in terms of the total number of electrons and the external potential leads to new relations among common density functional reactivity descriptors. The formulas obtained provide explicit links between important quantities related to the chemical reactivity of a system. In particular, the relation between the nuclear and the electronic Fukui functions is recovered. The connection between the derivatives of the electronic energy and the nuclear repulsion energy with respect to the external potential offers a proof for the "Quantum Chemical le Chatelier Principle." Finally, the nuclear linear response function is defined and the relation of this function with the electronic linear response function is given.

Building scientific confidence in metabolic similarity in read-across through the use of in vitro, in silico and analytical data

EPA Science Inventory

The underlying principle of read-across is that the biological activity of a chemical is inherent in its molecular structure. Analogues are typically identified by structural similarity then evaluated on the basis of their bioavailability, reactivity and metabolic similarity. Whi...

Selective Moral Disengagement in the Exercise of Moral Agency.

ERIC Educational Resources Information Center

Bandura, Albert

2002-01-01

Addresses the issue of selective moral disengagement in the exercise of moral agency. Argues that moral functioning is governed by self-reactive selfhood rather than by dispassionate abstract reasoning. Concludes that the massive threats to human welfare stem mainly from deliberate acts of principle rather than from unrestrained acts of impulse.…

20180312 - Building scientific confidence in metabolic similarity in read-across through the use of in vitro, in silico and analytical data (SOT)

EPA Science Inventory

The underlying principle of read-across is that the biological activity of a chemical is inherent in its molecular structure. Analogues are typically identified by structural similarity then evaluated on the basis of their bioavailability, reactivity and metabolic similarity. Whi...

Principles in redox signaling: from chemistry to functional significance.

PubMed

Bindoli, Alberto; Rigobello, Maria Pia

2013-05-01

Reactive oxygen and nitrogen species are currently considered not only harmful byproducts of aerobic respiration but also critical mediators of redox signaling. The molecules and the chemical principles sustaining the network of cellular redox regulated processes are described. Special emphasis is placed on hydrogen peroxide (H(2)O(2)), now considered as acting as a second messenger, and on sulfhydryl groups, which are the direct targets of the oxidant signal. Cysteine residues of some proteins, therefore, act as sensors of redox conditions and are oxidized in a reversible reaction. In particular, the formation of sulfenic acid and disulfide, the initial steps of thiol oxidation, are described in detail. The many cell pathways involved in reactive oxygen species formation are reported. Central to redox signaling processes are the glutathione and thioredoxin systems controlling H(2)O(2) levels and, hence, the thiol/disulfide balance. Lastly, some of the most important redox-regulated processes involving specific enzymes and organelles are described. The redox signaling area of research is rapidly expanding, and future work will examine new pathways and clarify their importance in cellular pathophysiology.

Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols.

PubMed

Nacsa, Eric D; MacMillan, David W C

2018-03-07

Nature routinely engages alcohols as leaving groups, as DNA biosynthesis relies on the removal of water from ribonucleoside diphosphates by a radical-mediated "spin-center shift" (SCS) mechanism. Alcohols, however, remain underused as alkylating agents in synthetic chemistry due to their low reactivity in two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide evidence for SCS as a key elementary step, identify the origins of competing reactions, and enable improvements in chemoselectivity by rational photocatalyst design.

Dehydration and dehydroxylation of C-S-H phases synthesized on silicon wafers

NASA Astrophysics Data System (ADS)

Giraudo, Nicolas; Bergdolt, Samuel; Laye, Fabrice; Krolla, Peter; Lahann, Joerg; Thissen, Peter

2018-03-01

In this work, the synthesis of specific ultrathin Calcium-Silicate-Hydrate (C-S-H) phases on silicon wafers and their transformation into C-S phases is achieved. Specific mineral phases are identified, and the synthesis is successful controlled. Samples are investigated by means of Fourier Transform Infrared (FTIR) spectroscopy and X-ray Diffraction (XRD) and the results are analyzed based on first-principles calculations. When C-S-H phases are transformed into C-S phases, only a few reflexes are detected on XRD, and the coherent scattering domains decrease with the increment of the temperature and time of exposure. This behavior is explained by the Ca/Si changes, which are identified by changes in the FTIR spectra. A thermodynamic analysis is performed with the help of first-principles calculations to underline the influence of the calcium-to-silicon (Ca/Si) ratio in the process of dehydroxylation. To increase the Ca/Si ratio water is partially substituted by methanol at the synthesis. This is observed in the FTIR spectra and is confirmed by lower temperatures of dehydroxylation. The catalytic nature of calcium towards the dehydroxylation is confirmed. The core of this work lies in the preparation of a model, which perfection makes possible to model reactivity, stability and mechanical properties using first-principles calculations, and is the starting point for the synthesis of many others.

Adsorption, hydrogenation and dehydrogenation of C2H on a CoCu bimetallic layer

NASA Astrophysics Data System (ADS)

Wu, Donghai; Yuan, Jinyun; Yang, Baocheng; Chen, Houyang

2018-05-01

In this paper, adsorption, hydrogenation and dehydrogenation of C2H on a single atomic layer of bimetallic CoCu were investigated using first-principles calculations. The CoCu bimetallic layer is formed by Cu replacement of partial Co atoms on the top layer of a Co(111) surface. Our adsorption and reaction results showed those sites, which have stronger adsorption energy of C2H, possess higher reactivity. The bimetallic layer possesses higher reactivity than either of the pure monometallic layer. A mechanism of higher reactivity of the bimetallic layer is proposed and identified, i.e. in the bimetallic catalyst, the catalytic performance of one component is promoted by the second component, and in our work, the catalytic performance of Co atoms in the bimetallic layer are improved by introducing Cu atoms, lowing the activation barrier of the reaction of C2H. The bimetallic layer could tune adsorption and reaction of C2H by modulating the ratio of Co and Cu. Results of adsorption energies and adsorption configurations reveal that C2H prefers to be adsorbed in parallel on both the pure Co metallic and CoCu bimetallic layers, and Co atoms in subsurface which support the metallic or bimetallic layer have little effect on C2H adsorption. For hydrogenation reactions, the products greatly depend on the concentration and initial positions of hydrogen atoms, and the C2H hydrogenation forming acetylene is more favorable than forming vinylidene in both thermodynamics and kinetics. This study would provide fundamental guidance for hydrocarbon reactions on Co-based and/or Cu-based bimetallic surface chemistry and for development of new bimetallic catalysts.

Dendritic cell immunotherapy followed by cART interruption during HIV-1 infection induces plasma protein markers of cellular immunity and neutrophil recruitment

PubMed Central

Cooper, Jason D.; Tomasik, Jakub; Bahn, Sabine; Aerts, Joeri L.; Osterhaus, Albert D. M. E.; Gruters, Rob A.; Andeweg, Arno C.

2018-01-01

Objectives To characterize the host response to dendritic cell-based immunotherapy and subsequent combined antiretroviral therapy (cART) interruption in HIV-1-infected individuals at the plasma protein level. Design An autologous dendritic cell (DC) therapeutic vaccine was administered to HIV-infected individuals, stable on cART. The effect of vaccination was evaluated at the plasma protein level during the period preceding cART interruption, during analytical therapy interruption and at viral reactivation. Healthy controls and post-exposure prophylactically treated healthy individuals were included as controls. Methods Plasma marker (‘analyte’) levels including cytokines, chemokines, growth factors, and hormones were measured in trial participants and control plasma samples using a multiplex immunoassay. Analyte levels were analysed using principle component analysis, cluster analysis and limma. Blood neutrophil counts were analysed using linear regression. Results Plasma analyte levels of HIV-infected individuals are markedly different from those of healthy controls and HIV-negative individuals receiving post-exposure prophylaxis. Viral reactivation following cART interruption also affects multiple analytes, but cART interruption itself only has only a minor effect. We find that Thyroxine-Binding Globulin (TBG) levels and late-stage neutrophil numbers correlate with the time off cART after DC vaccination. Furthermore, analysis shows that cART alters several regulators of blood glucose levels, including C-peptide, chromogranin-A and leptin. HIV reactivation is associated with the upregulation of CXCR3 ligands. Conclusions Chronic HIV infection leads to a change in multiple plasma analyte levels, as does virus reactivation after cART interruption. Furthermore, we find evidence for the involvement of TBG and neutrophils in the response to DC-vaccination in the setting of HIV-infection. PMID:29389978

Dendritic cell immunotherapy followed by cART interruption during HIV-1 infection induces plasma protein markers of cellular immunity and neutrophil recruitment.

PubMed

van den Ham, Henk-Jan; Cooper, Jason D; Tomasik, Jakub; Bahn, Sabine; Aerts, Joeri L; Osterhaus, Albert D M E; Gruters, Rob A; Andeweg, Arno C

2018-01-01

To characterize the host response to dendritic cell-based immunotherapy and subsequent combined antiretroviral therapy (cART) interruption in HIV-1-infected individuals at the plasma protein level. An autologous dendritic cell (DC) therapeutic vaccine was administered to HIV-infected individuals, stable on cART. The effect of vaccination was evaluated at the plasma protein level during the period preceding cART interruption, during analytical therapy interruption and at viral reactivation. Healthy controls and post-exposure prophylactically treated healthy individuals were included as controls. Plasma marker ('analyte') levels including cytokines, chemokines, growth factors, and hormones were measured in trial participants and control plasma samples using a multiplex immunoassay. Analyte levels were analysed using principle component analysis, cluster analysis and limma. Blood neutrophil counts were analysed using linear regression. Plasma analyte levels of HIV-infected individuals are markedly different from those of healthy controls and HIV-negative individuals receiving post-exposure prophylaxis. Viral reactivation following cART interruption also affects multiple analytes, but cART interruption itself only has only a minor effect. We find that Thyroxine-Binding Globulin (TBG) levels and late-stage neutrophil numbers correlate with the time off cART after DC vaccination. Furthermore, analysis shows that cART alters several regulators of blood glucose levels, including C-peptide, chromogranin-A and leptin. HIV reactivation is associated with the upregulation of CXCR3 ligands. Chronic HIV infection leads to a change in multiple plasma analyte levels, as does virus reactivation after cART interruption. Furthermore, we find evidence for the involvement of TBG and neutrophils in the response to DC-vaccination in the setting of HIV-infection.

Reactivity-based drug discovery using vitamin B(6)-derived pharmacophores.

PubMed

Wondrak, Georg T

2008-05-01

Endogenous reactive intermediates including photoexcited states of tissue chromophores, reactive oxygen species (ROS), reactive carbonyl species (RCS), transition metal ions, and Schiff bases have been implicated in the initiation and progression of diverse human pathologies including tumorigenesis, atherosclerosis, diabetes, and neurodegenerative disease. In contrast to structure-based approaches that target macromolecules by selective ligands, reactivity-based drug discovery uses chemical reagents as therapeutics that target reactive chemical species involved in human pathology. Reactivity-based design of prototype agents that effectively antagonize, modulate, and potentially even reverse the chemistry underlying tissue damage from oxidative and carbonyl stress therefore holds great promise in delivering significant therapeutic benefit. Apart from its established role as an essential cofactor for numerous enzymes, a large body of evidence suggests that B(6)-vitamers contain reactive pharmacophores that mediate therapeutically useful non-vitamin drug actions as potent antioxidants, metal chelators, carbonyl scavengers, Schiff base forming agents, and photosensitizers. Based on the fascinating chemical versatility of B(6)-derived pharmacophores, B(6)-vitamers are therefore promising lead compounds for reactivity-based drug design.

Structural stability and electronic properties of an octagonal allotrope of two dimensional boron nitride.

PubMed

Takahashi, Lauren; Takahashi, Keisuke

2017-03-27

An octagonal allotrope of two dimensional boron nitride is explored through first principles calculations. Calculations show that two dimensional octagonal boron nitride can be formed with a binding energy comparable to two dimensional hexagonal boron nitride. In addition, two dimensional octagonal boron nitride is found to have a band gap smaller than two dimensional hexagonal boron nitride, suggesting the possibility of semiconductive attributes. Two dimensional octagonal boron nitride also has the ability to layer through physisorption. Defects present within two dimensional octagonal boron nitride also lead toward the introduction of a magnetic moment through the absence of boron atoms. The presence of defects is also found to render both hexagonal and octagonal boron nitrides reactive against hydrogen, where greater reactivity is seen in the presence of nitrogen. Thus, two dimensional octagonal boron nitride is confirmed with potential to tailor properties and reactivity through lattice shape and purposeful introduction of defects.

Comparisons between mammalian and artificial olfaction based on arrays of carbon black-polymer composite vapor detectors.

PubMed

Lewis, Nathan S

2004-09-01

Arrays of broadly cross-reactive vapor sensors provide a man-made implementation of an olfactory system, in which an analyte elicits a response from many receptors and each receptor responds to a variety of analytes. Pattern recognition methods are then used to detect analytes based on the collective response of the sensor array. With the use of this architecture, arrays of chemically sensitive resistors made from composites of conductors and insulating organic polymers have been shown to robustly classify, identify, and quantify a diverse collection of organic vapors, even though no individual sensor responds selectively to a particular analyte. The properties and functioning of these arrays are inspired by advances in the understanding of biological olfaction, and in turn, evaluation of the performance of the man-made array provides suggestions regarding some of the fundamental odor detection principles of the mammalian olfactory system.

An Efficient Glycoblotting-Based Analysis of Oxidized Lipids in Liposomes and a Lipoprotein.

PubMed

Furukawa, Takayuki; Hinou, Hiroshi; Takeda, Seiji; Chiba, Hitoshi; Nishimura, Shin-Ichiro; Hui, Shu-Ping

2017-10-05

Although widely occurring lipid oxidation, which is triggered by reactive oxygen species (ROS), produces a variety of oxidized lipids, practical methods to efficiently analyze oxidized lipids remain elusive. Herein, it is shown that the glycoblotting platform can be used to analyze oxidized lipids. Analysis is based on the principle that lipid aldehydes, one of the oxidized lipid species, can be captured selectively, enriched, and detected. Moreover, 3-methyl-1-p-tolyltriazene (MTT) methylates phosphoric and carboxylic acids, and this MTT-mediated methylation is, in combination with conventional tandem mass spectrometry (MS/MS) analysis, an effective method for the structural analysis of oxidized lipids. By using three classes of standards, liposomes, and a lipoprotein, it is demonstrated that glycoblotting represents a powerful approach for focused lipidomics, even in complex macromolecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prediction of mass transfer coefficients in non-Newtonian fermentation media using first-principles methods.

PubMed

Radl, Stefan; Khinast, Johannes G

2007-08-01

Bubble flows in non-Newtonian fluids were analyzed using first-principles methods with the aim to compute and predict mass transfer coefficients in such fermentation media. The method we used is a Direct Numerical Simulation (DNS) of the reactive multiphase flow with deformable boundaries and interfaces. With this method, we are able for the first time to calculate mass transfer coefficients in non-Newtonian liquids of different rheologies without any experimental data. In the current article, shear-thinning fluids are considered. However, the results provide the basis for further investigations, such as the study of viscoelastic fluids. (c) 2007 Wiley Periodicals, Inc.

Operationally Simple Synthesis of N,N-Diethyl-3-Methylbenzamide (DEET) Using COMU as a Coupling Reagent

ERIC Educational Resources Information Center

Withey, Jonathan M.; Bajic, Andrea

2015-01-01

A novel procedure is described where students use COMU [(1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate], as a nonhazardous partner, in the one-pot coupling of a carboxylic acid and amine producing N,N-diethyl-3-methylbenzamide (DEET). Fundamental principles of carbonyl reactivity are understood,…

A New Higher Education Curriculum in Organic Chemistry: What Questions Should Be Asked?

ERIC Educational Resources Information Center

Lafarge, David L.; Morge, Ludovic M.; Méheut, Martine M.

2014-01-01

Organic chemistry is often considered to be a difficult subject to teach and to learn, particularly as students prefer to resort to memorization alone rather than reasoning using models from chemical reactivity. Existing studies have led us to suggest principles for redefining the curriculum, ranging from its overall structure to the tasks given…

CTLs directed against HER2 specifically cross-react with HER3 and HER4.

PubMed

Conrad, Heinke; Gebhard, Kerstin; Krönig, Holger; Neudorfer, Julia; Busch, Dirk H; Peschel, Christian; Bernhard, Helga

2008-06-15

The human epidermal growth factor receptor 2 (HER2) has been targeted as a breast cancer-associated Ag by T cell-based immunotherapeutical strategies such as cancer vaccines and adoptive T cell transfer. The prerequisite for a successful T cell-based therapy is the induction of T cells capable of recognizing the HER2-expressing tumor cells. In this study, we generated human cytotoxic T cell clones directed against the HER2(369-377) epitope known to be naturally presented with HLA-A*0201. Those HER2-reactive CTLs, which were also tumor lytic, exhibited a similar lysis pattern dividing the targets in lysable and nonlysable tumor cells. Several HER2-expressing tumor cells became susceptible to CTL-mediated lysis after IFN-gamma treatment and, in parallel, up-regulated molecules of the Ag-presenting machinery, indicating that the tumor itself also contributes to the success of CTL-mediated killing. Some of the HER2(369-377)-reactive T cells specifically cross-reacted with the corresponding peptides derived from the family members HER3 and/or HER4 due to a high sequence homology. The epitopes HER3(356-364) and HER4(361-369) were endogenously processed and contributed to the susceptibility of cell lysis by HER cross-reacting CTLs. The principle of "double" or "triple targeting" the HER Ags by cross-reacting T cells will impact the further development of T cell-based therapies.

Reactive Distillation and Air Stripping Processes for Water Recycling and Trace Contaminant Control

NASA Technical Reports Server (NTRS)

Boul, Peter J.; Lange, Kevin E.; Conger, Bruce; Anderson, Molly

2009-01-01

Reactive distillation designs are considered to reduce the presence of volatile organic compounds in the purified water. Reactive distillation integrates a reactor with a distillation column. A review of the literature in this field has revealed a variety of functional reactive columns in industry. Wastewater may be purified by a combination of a reactor and a distiller (e.g., the EWRS or VPCAR concepts) or, in principle, through a design which integrates the reactor with the distiller. A review of the literature in reactive distillation has identified some different designs in such combinations of reactor and distiller. An evaluation of reactive distillation and reactive air stripping is presented with regards to the reduction of volatile organic compounds in the contaminated water and air. Among the methods presented, an architecture is presented for the evaluation of the simultaneous oxidation of organics in air and water. These and other designs are presented in light of potential improvements in power consumptions and air and water purities for architectures which include catalytic activity integrated into the water processor. In particular, catalytic oxidation of organics may be useful as a tool to remove contaminants that more traditional distillation and/or air stripping columns may not remove. A review of the current leading edge at the commercial level and at the research frontier in catalytically active materials is presented. Themes and directions from the engineering developments in catalyst design are presented conceptually in light of developments in the nanoscale chemistry of a variety of catalyst materials.

Unlocking Ft: Modeling thermodynamic controls and isotope fractionation factors in nutrient limited environments

NASA Astrophysics Data System (ADS)

Druhan, J. L.; Giannetta, M.; Sanford, R. A.

2017-12-01

In recent years, reactive transport principles have expanded from early applications, largely based in contaminant hydrology, to a wide range of biologically mediated redox environments including marine sedimentary diagenesis, terrestrial metal ore deposits, soils, and critical zone weathering profiles. A common observation across this diversity of systems is that they often function under energetically limited conditions in comparison to those typical of contaminated aquifers subject to engineered remediation techniques. As a result, the kinetic rate expressions traditionally employed within reactive transport frameworks to simulate microbially mediated redox transformations have required modification. This was recognized in a series of seminal papers by Jin and Bethke (2005, 2007) in which the authors expanded upon a Monod rate law to include a thermodynamic potential factor `Ft' which exerts a limitation on the overall rate based on the thermodynamic driving force of the electron transfer reaction. This new rate expression is now commonly implemented within many of the major reactive transport software packages, though appropriate application has yet to be thoroughly demonstrated. Notably, the characteristically large partitioning of stable isotopes during microbially mediated reactions, which is extensively utilized to identify and quantify these redox transformations, has yet to be simulated under conditions in which the Ft term may be expected to exert a significant mass dependent influence. Here, we develop a series of simplified simulations for the microbially mediated reduction of sulfate based on the datasets reported by Jin and Bethke, and apply appropriate mass-bias within the Ft term to consider the extent to which the resulting isotopic fractionation is consistent with that observed in energetically limited systems. We show that the Ft term can exert a significant influence on the observed fractionation factor under common environmental conditions, resulting in model behavior which is, in effect, a microbial redox analog to the variable observed fractionation factor resulting from a transition state theory rate law as derived by DePaolo (2011).

Understanding Combustion of H2/O2 Gases inside Nanobubbles Generated by Water Electrolysis Using Reactive Molecular Dynamic Simulations.

PubMed

Jain, S; Qiao, L

2018-06-21

This work explored the mechanism of spontaneous combustion of hydrogen-oxygen mixtures inside nanobubbles (which were generated by water electrolysis) using reactive molecular dynamic simulations based on the first-principles derived reactive force field ReaxFF. The effects of surface-assisted dissociation of H 2 and O 2 gases that produced H and O radicals were examined. Additionally, the ignition outcome and species evolution as a function of the initial system pressure (or bubble size) were studied. A significant amount of hydrogen peroxide (H 2 O 2 ), 6-140 times water (H 2 O), was observed in the combustion products. This was attributed to the low-temperature (∼300 K) and high-pressure (2-80 atm) conditions at which the chemical reactions were taking place. In addition, the rate of consumption of H 2 and O 2 molecules was found to increase with an increase in added H and O radical concentrations and initial system pressure. The rate at which heat was being lost from the combustion chamber (nanobubbles) was also compared to the rate at which heat was being released from the chemical reactions. Only a slight rise in the reaction temperature was observed (∼68 K), signifying that, at such small scales, heat losses dominate. The resulting chemistry was quite different from macroscopic combustion, which usually takes place at a much higher temperatures of above 1000 K.

Development of an evidence-based protocol for care of pilonidal sinus wounds healing by secondary intent using a modified reactive Delphi procedure. Part one: the literature review*.

PubMed

Harris, Connie L; Holloway, Samantha

2012-04-01

This article is in two parts. The overall aim of this section was to review the literature in relation to pilonidal sinus wounds (PSW) healing by secondary intent for a Master's of Science in Wound Healing and Tissue Repair thesis. The purpose of the literature review was to determine if an evidence-based guideline or consensus document existed for the care of these wounds, and if not, to determine the topics from which to develop items for the first round of a modified reactive Delphi questionnaire. Part two will describe the iterative process, the analysis and the results. The review found no best practice guidelines concerning PSW, and only one clinical pathway. Seventeen areas of interest were identified that may contribute to optimal healing conditions or to delayed healing. These included microbiology of infected PSW, signs and symptoms of localised or deeper (spreading) chronic wound infection, swab for c&s, role of topical antiseptics or antimicrobials, systemic antibiotics, local wound interventions, optimal positioning, wound cleansing, principles of moist wound healing/dressing selection, topical negative pressure (TNP) therapy, peri-wound skin decontamination and depilation, pain control, physical activities, optimal nutrition and patient education. © 2011 The Authors. © 2011 Blackwell Publishing Ltd and Medicalhelplines.com Inc.

Optimization of power systems with voltage security constraints

NASA Astrophysics Data System (ADS)

Rosehart, William Daniel

As open access market principles are applied to power systems, significant changes in their operation and control are occurring. In the new marketplace, power systems are operating under higher loading conditions as market influences demand greater attention to operating cost versus stability margins. Since stability continues to be a basic requirement in the operation of any power system, new tools are being considered to analyze the effect of stability on the operating cost of the system, so that system stability can be incorporated into the costs of operating the system. In this thesis, new optimal power flow (OPF) formulations are proposed based on multi-objective methodologies to optimize active and reactive power dispatch while maximizing voltage security in power systems. The effects of minimizing operating costs, minimizing reactive power generation and/or maximizing voltage stability margins are analyzed. Results obtained using the proposed Voltage Stability Constrained OPF formulations are compared and analyzed to suggest possible ways of costing voltage security in power systems. When considering voltage stability margins the importance of system modeling becomes critical, since it has been demonstrated, based on bifurcation analysis, that modeling can have a significant effect of the behavior of power systems, especially at high loading levels. Therefore, this thesis also examines the effects of detailed generator models and several exponential load models. Furthermore, because of its influence on voltage stability, a Static Var Compensator model is also incorporated into the optimization problems.

Extending atomistic scale chemistry to mesoscale model of condensed-phase deflagration

NASA Astrophysics Data System (ADS)

Joshi, Kaushik; Chaudhuri, Santanu

2017-01-01

Predictive simulations connecting chemistry that follow the shock or thermal initiation of energetic materials to subsequent deflagration or detonation events is currently outside the realm of possibilities. Molecular dynamics and first-principles based dynamics have made progress in understanding reactions in picosecond to nanosecond time scale. Results from thermal ignition of different phases of RDX show a complex reaction network and emergence of a deterministic behavior for critical temperature before ignition and hot spot growth rates. The kinetics observed is dependent on the hot spot temperature, system size and thermal conductivity. For cases where ignition is observed, the incubation period is dominated by intermolecular and intramolecular hydrogen transfer reactions. The gradual temperature and pressure increase in the incubation period is accompanied by accumulation of heavier polyradicals. The challenge of connecting such chemistry in mesoscale simulations remain in reducing the complexity of chemistry. The hot spot growth kinetics in RDX grains and interfaces is an important challenge for reactive simulations aiming to fill in the gaps in our knowledge in the nanoseconds to microseconds time scale. The results discussed indicate that the mesoscale chemistry may include large polyradical molecules in dense reactive mix reaching an instability point at certain temperatures and pressures.

Grotthuss Transport of Iodide in EMIM/I3 Ionic Crystal.

PubMed

McDaniel, Jesse G; Yethiraj, Arun

2018-01-11

Highly ionic environments can mediate unusual chemical reactions that would otherwise be considered impossible based on chemical intuition. For example, the formation of a chemical bond between two iodide anions to form a divalent polyiodide anion is seemingly prohibited due to Coulombic repulsion. Using ab initio molecular dynamics simulations, we show that in the 1-ethyl-3-methylimidazolium (EMIM)/I 3 ionic crystal, the reactive formation of divalent and even trivalent polyiodide anions occurs with extremely small energetic barriers, due to the electrostatic field of the ionic lattice. A practical consequence of this anomalous reactivity is that iodide anions are efficiently transported within the crystal through a "Grotthuss-exchange" mechanism involving bond-breaking and forming events. We characterize two distinct transport pathways, involving both I 4 2- and I 7 3- intermediates, with fast transport of iodide resulting from the release of an I - anion on the opposite side of the intermediate species from the initial bond formation. The ordered cation arrangement in the crystal provides the necessary electrostatic screening for close approach of anions, suggesting a new counterintuitive approach to obtain high ionic conductivity. This new design principle could be used to develop better solid-state electrolytes for batteries, fuel cells, and supercapacitors.

Flash chemistry: flow microreactor synthesis based on high-resolution reaction time control.

PubMed

Yoshida, Jun-ichi

2010-10-01

This article addresses a fascinating aspect of flash chemistry, high-resolution reaction-time control by virtue of a flow microreactor system, and its applications. The length of time that the solution remains inside the reactor is called the residence time. The residence time between the addition of a reagent and that of a quenching agent or the next reagent in a flow microreactor is the reaction time, and the reaction time can be greatly reduced by adjusting the length of a reaction channel in a flow microreactor. This feature is quite effective for conducting reactions involving short-lived reactive intermediates. A reactive species can be generated and transferred to another location to be used in the next reaction before it decomposes by adjusting the residence time in the millisecond to second timescale. The principle of such high-resolution reaction-time control, which can be achieved only by flow microreactors, and its applications to synthetic reactions including Swern-Moffatt-type oxidation, as well as the generation and reactions of aryllithium compounds bearing electrophilic substituents, such as alkoxycarbonyl groups, are presented. Integration of such reactions using integrated flow microreactor systems is also demonstrated. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Investigation of Gasochromic Rhodium Complexes Towards Their Reactivity to CO and Integration into an Optical Gas Sensor for Fire Gas Detection.

PubMed

Pannek, Carolin; Tarantik, Karina R; Schmitt, Katrin; Wöllenstein, Jürgen

2018-06-21

The detection of the toxic gas carbon monoxide (CO) in the low ppm range is required in different applications. We present a study of the reactivity of different gasochromic rhodium complexes towards the toxic gas carbon monoxide (CO). Therefore, variations of binuclear rhodium complexes with different ligands were prepared. They were characterized by FTIR spectroscopy, ¹H NMR spectroscopy, and differential scanning calorimetry. All complexes are spectroscopically distinguishable and temperature stable up to at least 187 °C. The gasochromic behavior of all different compounds was tested. Therefore, the compounds were dissolved in toluene and exposed to 100 ppm CO for 10 min to investigate their gas sensitivity and reaction velocity. The changes in the transmission spectra were recorded by UV/vis spectroscopy. Furthermore, a significant influence of the solvent to the color dyes’ gasochromic reaction and behavior was observed. After characterization, one complex was transferred as sensing element into an optical gas sensor. Two different measurement principles (reflection- and waveguide-based) were built up and tested towards their capability as gasochromic CO sensors. Finally, different gas-dependent measurements were carried out.

Murburn Concept: A Molecular Explanation for Hormetic and Idiosyncratic Dose Responses.

PubMed

Parashar, Abhinav; Gideon, Daniel Andrew; Manoj, Kelath Murali

2018-01-01

Recently, electron transfers and catalyses in a bevy of redox reactions mediated by hemeproteins were explained by murburn concept. The term "murburn" is abstracted from " mur ed burn ing " or " m ild u n r estricted burn ing " and connotes a novel " m olecule- u nbound ion- r adical " interaction paradigm. Quite unlike the genetic regulations and protein-level affinity-based controls that govern order and specificity/selectivity in conventional treatments, murburn concept is based on stochastic/thermodynamic regulatory principles. The novel insight necessitates a "reactivity outside the active-site" perspective, because select redox enzymatic activity is obligatorily mediated via diffusible radical/species. Herein, reactions employing key hemeproteins (as exemplified by CYP2E1) establish direct experimental connection between "additive-influenced redox catalysis" and "unusual dose responses" in reductionist and physiological milieu. Thus, direct and conclusive molecular-level experimental evidence is presented, supporting the mechanistic relevance of murburn concept in "maverick" concentration-based effects brought about by additives. Therefore, murburn concept could potentially explain several physiological hormetic and idiosyncratic dose responses.

Super-oxidation of silicon nanoclusters: magnetism and reactive oxygen species at the surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepeshkin, Sergey; Baturin, Vladimir; Tikhonov, Evgeny

2016-01-01

Oxidation of silicon nanoclusters depending on the temperature and oxygen pressure is explored from first principles using the evolutionary algorithm, and structural and thermodynamic analysis. From our calculations of 90 SinOm clusters we found that under normal conditions oxidation does not stop at the stoichiometric SiO2 composition, as it does in bulk silicon, but goes further placing extra oxygen atoms on the cluster surface. These extra atoms are responsible for light emission, relevant to reactive oxygen species and many of them are magnetic. We argue that the super-oxidation effect is size-independent and discuss its relevance to nanotechnology and miscellaneous applications,more » including biomedical ones.« less

Reactive Monte Carlo sampling with an ab initio potential

NASA Astrophysics Data System (ADS)

Leiding, Jeff; Coe, Joshua D.

2016-05-01

We present the first application of reactive Monte Carlo in a first-principles context. The algorithm samples in a modified NVT ensemble in which the volume, temperature, and total number of atoms of a given type are held fixed, but molecular composition is allowed to evolve through stochastic variation of chemical connectivity. We discuss general features of the method, as well as techniques needed to enhance the efficiency of Boltzmann sampling. Finally, we compare the results of simulation of NH3 to those of ab initio molecular dynamics (AIMD). We find that there are regions of state space for which RxMC sampling is much more efficient than AIMD due to the "rare-event" character of chemical reactions.

Bismuth vanadate-based semiconductor photocatalysts: a short critical review on the efficiency and the mechanism of photodegradation of organic pollutants.

PubMed

Monfort, Olivier; Plesch, Gustav

2018-06-02

The number of publications on photocatalytic bismuth vanadate-based materials is constantly increasing. Indeed, bismuth vanadate is gaining stronger interest in the photochemical community since it is a solar-driven photocatalyst. However, the efficiency of BiVO 4 -based photocatalyst under sunlight is questionable: in most of the studies investigating the photodegradation of organic pollutants, only few works identify the by-products and evaluate the real efficiency of BiVO 4 -based materials. This short review aims to (i) present briefly the principles of photocatalysis and define the photocatalytic efficiency and (ii) discuss the formation of reactive species involved in the photocatalytic degradation process of pollutants and thus the corresponding photodegradation mechanism could be determined. All these points are developed in a comprehensive discussion by focusing especially on pure, doped, and composite BiVO 4 . Therefore, this review exhibits a critical overview on different BiVO 4 -based photocatalytic systems with their real efficiency. This is a necessary knowledge for potential implementation of BiVO 4 materials in environmental applications at larger scale than laboratory conditions.

A theory for bioinorganic chemical reactivity of oxometal complexes and analogous oxidants: the exchange and orbital-selection rules.

PubMed

Usharani, Dandamudi; Janardanan, Deepa; Li, Chunsen; Shaik, Sason

2013-02-19

Over the past decades metalloenzymes and their synthetic models have emerged as an area of increasing research interest. The metalloenzymes and their synthetic models oxidize organic molecules using oxometal complexes (OMCs), especially oxoiron(IV)-based ones. Theoretical studies have helped researchers to characterize the active species and to resolve mechanistic issues. This activity has generated massive amounts of data on the relationship between the reactivity of OMCs and the transition metal's identity, oxidation state, ligand sphere, and spin state. Theoretical studies have also produced information on transition state (TS) structures, reaction intermediates, barriers, and rate-equilibrium relationships. For example, the experimental-theoretical interplay has revealed that nonheme enzymes carry out H-abstraction from strong C-H bonds using high-spin (S = 2) oxoiron(IV) species with four unpaired electrons on the iron center. However, other reagents with higher spin states and more unpaired electrons on the metal are not as reactive. Still other reagents carry out these transformations using lower spin states with fewer unpaired electrons on the metal. The TS structures for these reactions exhibit structural selectivity depending on the reactive spin states. The barriers and thermodynamic driving forces of the reactions also depend on the spin state. H-Abstraction is preferred over the thermodynamically more favorable concerted insertion into C-H bonds. Currently, there is no unified theoretical framework that explains the totality of these fascinating trends. This Account aims to unify this rich chemistry and understand the role of unpaired electrons on chemical reactivity. We show that during an oxidative step the d-orbital block of the transition metal is enriched by one electron through proton-coupled electron transfer (PCET). That single electron elicits variable exchange interactions on the metal, which in turn depend critically on the number of unpaired electrons on the metal center. Thus, we introduce the exchange-enhanced reactivity (EER) principle, which predicts the preferred spin state during oxidation reactions, the dependence of the barrier on the number of unpaired electrons in the TS, and the dependence of the deformation energy of the reactants on the spin state. We complement EER with orbital-selection rules, which predict the structure of the preferred TS and provide a handy theory of bioinorganic oxidative reactions. These rules show how EER provides a Hund's Rule for chemical reactivity: EER controls the reactivity landscape for a great variety of transition-metal complexes and substrates. Among many reactivity patterns explained, EER rationalizes the abundance of high-spin oxoiron(IV) complexes in enzymes that carry out bond activation of the strongest bonds. The concepts used in this Account might also be applicable in other areas such as in f-block chemistry and excited-state reactivity of 4d and 5d OMCs.

Generic reactive transport codes as flexible tools to integrate soil organic matter degradation models with water, transport and geochemistry in soils

NASA Astrophysics Data System (ADS)

Jacques, Diederik; Gérard, Fréderic; Mayer, Uli; Simunek, Jirka; Leterme, Bertrand

2016-04-01

A large number of organic matter degradation, CO2 transport and dissolved organic matter models have been developed during the last decades. However, organic matter degradation models are in many cases strictly hard-coded in terms of organic pools, degradation kinetics and dependency on environmental variables. The scientific input of the model user is typically limited to the adjustment of input parameters. In addition, the coupling with geochemical soil processes including aqueous speciation, pH-dependent sorption and colloid-facilitated transport are not incorporated in many of these models, strongly limiting the scope of their application. Furthermore, the most comprehensive organic matter degradation models are combined with simplified representations of flow and transport processes in the soil system. We illustrate the capability of generic reactive transport codes to overcome these shortcomings. The formulations of reactive transport codes include a physics-based continuum representation of flow and transport processes, while biogeochemical reactions can be described as equilibrium processes constrained by thermodynamic principles and/or kinetic reaction networks. The flexibility of these type of codes allows for straight-forward extension of reaction networks, permits the inclusion of new model components (e.g.: organic matter pools, rate equations, parameter dependency on environmental conditions) and in such a way facilitates an application-tailored implementation of organic matter degradation models and related processes. A numerical benchmark involving two reactive transport codes (HPx and MIN3P) demonstrates how the process-based simulation of transient variably saturated water flow (Richards equation), solute transport (advection-dispersion equation), heat transfer and diffusion in the gas phase can be combined with a flexible implementation of a soil organic matter degradation model. The benchmark includes the production of leachable organic matter and inorganic carbon in the aqueous and gaseous phases, as well as different decomposition functions with first-order, linear dependence or nonlinear dependence on a biomass pool. In addition, we show how processes such as local bioturbation (bio-diffusion) can be included implicitly through a Fickian formulation of transport of soil organic matter. Coupling soil organic matter models with generic and flexible reactive transport codes offers a valuable tool to enhance insights into coupled physico-chemical processes at different scales within the scope of C-biogeochemical cycles, possibly linked with other chemical elements such as plant nutrients and pollutants.

CO2 Capture and Conversion on Rutile TiO2(110) in the Water Environment: Insight by First-Principles Calculations.

PubMed

Yin, Wen-Jin; Krack, Matthias; Wen, Bo; Ma, Shang-Yi; Liu, Li-Min

2015-07-02

The conversion of CO2 by the virtue of sunlight has the great potential to produce useful fuels or valuable chemicals while decreasing CO2 emission from the traditional fossil fuels. Here, we use the first-principles calculations combined with the periodic continuum solvation model (PCSM) to explore the adsorption and reactivity of CO2 on rutile TiO2(110) in the water environment. The results exhibit that both adsorption structures and reactivity of CO2 are greatly affected by water coadsorption on rutile TiO2(110). In particular, the solvation effect can change the most stable adsorption configuration of CO2 and H2O on rutile TiO2(110). In addition, the detailed conversion mechanism of CO2 reduction is further explored in the water environment. The results reveal that the solvation effect cannot only greatly decrease the energy barrier of CO2 reduction but also affect the selectivity of the reaction processes. These results presented here show the importance of the aqueous solution, which should be helpful to understand the detailed reaction processes of photocatalysts.

Addressing global uncertainty and sensitivity in first-principles based microkinetic models by an adaptive sparse grid approach

NASA Astrophysics Data System (ADS)

Döpking, Sandra; Plaisance, Craig P.; Strobusch, Daniel; Reuter, Karsten; Scheurer, Christoph; Matera, Sebastian

2018-01-01

In the last decade, first-principles-based microkinetic modeling has been developed into an important tool for a mechanistic understanding of heterogeneous catalysis. A commonly known, but hitherto barely analyzed issue in this kind of modeling is the presence of sizable errors from the use of approximate Density Functional Theory (DFT). We here address the propagation of these errors to the catalytic turnover frequency (TOF) by global sensitivity and uncertainty analysis. Both analyses require the numerical quadrature of high-dimensional integrals. To achieve this efficiently, we utilize and extend an adaptive sparse grid approach and exploit the confinement of the strongly non-linear behavior of the TOF to local regions of the parameter space. We demonstrate the methodology on a model of the oxygen evolution reaction at the Co3O4 (110)-A surface, using a maximum entropy error model that imposes nothing but reasonable bounds on the errors. For this setting, the DFT errors lead to an absolute uncertainty of several orders of magnitude in the TOF. We nevertheless find that it is still possible to draw conclusions from such uncertain models about the atomistic aspects controlling the reactivity. A comparison with derivative-based local sensitivity analysis instead reveals that this more established approach provides incomplete information. Since the adaptive sparse grids allow for the evaluation of the integrals with only a modest number of function evaluations, this approach opens the way for a global sensitivity analysis of more complex models, for instance, models based on kinetic Monte Carlo simulations.

Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first-principles calculations.

PubMed

Andrés, Juan; Gracia, Lourdes; Gouveia, Amanda Fernandes; Ferrer, Mateus Meneghetti; Longo, Elson

2015-10-09

Morphology is a key property of materials. Owing to their precise structure and morphology, crystals and nanocrystals provide excellent model systems for joint experimental and theoretical investigations into surface-related properties. Faceted polyhedral crystals and nanocrystals expose well-defined crystallographic planes depending on the synthesis method, which allow for thoughtful investigations into structure-reactivity relationships under practical conditions. This feature article introduces recent work, based on the combined use of experimental findings and first-principles calculations, to provide deeper knowledge of the electronic, structural, and energetic properties controlling the morphology and the transformation mechanisms of different metals and metal oxides: Ag, anatase TiO2, BaZrO3, and α-Ag2WO4. According to the Wulff theorem, the equilibrium shapes of these systems are obtained from the values of their respective surface energies. These investigations are useful to gain further understanding of how to achieve morphological control of complex three-dimensional crystals by tuning the ratio of the surface energy values of the different facets. This strategy allows the prediction of possible morphologies for a crystal and/or nanocrystal by controlling the relative values of surface energies.

The principle of homologous groups in regulatory affairs of allergen products--a proposal.

PubMed

Lorenz, A R; Lüttkopf, D; May, S; Scheurer, S; Vieths, S

2009-01-01

Among other legal regulations, the Note for Guidance on Allergen Products CPMP/BWP/243/96 released by the European Medicines Agency provides regulatory instructions regarding the quality of allergen extracts for diagnostic or therapeutic purposes. The current revision of this guideline intends to transform the so-called 'principle of taxonomic families' to the 'principle of homologous groups'. According to this concept, the data of one allergen extract demonstrating stability, efficacy and safety can, to a limited extent, be extrapolated to other allergen extracts belonging to the same homologous groups. The present work proposes the formation of homologous groups for pollen species and animal-derived materials on the basis of similar biochemical composition and homology/cross-reactivity of allergens or allergen sources. Some tree pollen species could be assigned to three different homologous groups, some weed pollen species to one homologous group and numerous grass pollen species to one homologous group on condition that data rely on single defined representative species. A homologous group for mites is limited to the Dermatophagoides species and the grouping of vertebrate-derived materials such as dander could be possible under restrictions. The criteria for the formation of the proposed homologous groups are illustrated in detail to provide an opportunity for extending existing homologous groups by further species in case of new insights in allergens and cross-reactivity of allergen sources. In this way, the concept of homologous groups could serve as a dynamic tool in the regulation of allergen products. (c) 2008 S. Karger AG, Basel.

Rationally engineered flavin-dependent oxidase reveals steric control of dioxygen reduction.

PubMed

Zafred, Domen; Steiner, Barbara; Teufelberger, Andrea R; Hromic, Altijana; Karplus, P Andrew; Schofield, Christopher J; Wallner, Silvia; Macheroux, Peter

2015-08-01

The ability of flavoenzymes to reduce dioxygen varies greatly, and is controlled by the protein environment, which may cause either a rapid reaction (oxidases) or a sluggish reaction (dehydrogenases). Previously, a 'gatekeeper' amino acid residue was identified that controls the reactivity to dioxygen in proteins from the vanillyl alcohol oxidase superfamily of flavoenzymes. We have identified an alternative gatekeeper residue that similarly controls dioxygen reactivity in the grass pollen allergen Phl p 4, a member of this superfamily that has glucose dehydrogenase activity and the highest redox potential measured in a flavoenzyme. A substitution at the alternative gatekeeper site (I153V) transformed the enzyme into an efficient oxidase by increasing dioxygen reactivity by a factor of 60,000. An inverse exchange (V169I) in the structurally related berberine bridge enzyme (BBE) decreased its dioxygen reactivity by a factor of 500. Structural and biochemical characterization of these and additional variants showed that our model enzymes possess a cavity that binds an anion and resembles the 'oxyanion hole' in the proximity of the flavin ring. We showed also that steric control of access to this site is the most important parameter affecting dioxygen reactivity in BBE-like enzymes. Analysis of flavin-dependent oxidases from other superfamilies revealed similar structural features, suggesting that dioxygen reactivity may be governed by a common mechanistic principle. Structural data are available in PDB database under the accession numbers 4PVE, 4PVH, 4PVJ, 4PVK, 4PWB, 4PWC and 4PZF. © 2015 FEBS.

Enhancing Tumor Drug Delivery by Laser-Activated Vascular Barrier Disruption

DTIC Science & Technology

2006-12-01

increased, which leads to normal tissue toxicity . This delivery problem not only limits the clinical application of existing chemotherapeutics, but also...principles and uses photochemical reactions to generate biological effectors, such as reactive oxygen species (ROS), which cause oxidative damage to...liposomes, mi- celles, and biodegradable nanoparticles , or conju- gated with hydrophilic polymers.6 It is likely that although some level of

Linking Fearfulness and Coping Styles in Fish

PubMed Central

Martins, Catarina I. M.; Silva, Patricia I. M.; Conceição, Luis E. C.; Costas, Benjamin; Höglund, Erik; Øverli, Øyvind; Schrama, Johan W.

2011-01-01

Consistent individual differences in cognitive appraisal and emotional reactivity, including fearfulness, are important personality traits in humans, non-human mammals, and birds. Comparative studies on teleost fishes support the existence of coping styles and behavioral syndromes also in poikilothermic animals. The functionalist approach to emotions hold that emotions have evolved to ensure appropriate behavioral responses to dangerous or rewarding stimuli. Little information is however available on how evolutionary widespread these putative links between personality and the expression of emotional or affective states such as fear are. Here we disclose that individual variation in coping style predicts fear responses in Nile tilapia Oreochromis niloticus, using the principle of avoidance learning. Fish previously screened for coping style were given the possibility to escape a signalled aversive stimulus. Fearful individuals showed a range of typically reactive traits such as slow recovery of feed intake in a novel environment, neophobia, and high post-stress cortisol levels. Hence, emotional reactivity and appraisal would appear to be an essential component of animal personality in species distributed throughout the vertebrate subphylum. PMID:22140511

Characterization of Impact Initiation of Aluminum-Based Intermetallic-Forming Reactive Materials

DTIC Science & Technology

2011-12-01

compressed intermetallic-forming aluminum-based reactive materials upon impact initiation, consisting of equi-volumetric tantalum-aluminum, tungsten-aluminum...18 2.3.4 Dynamic Energy Release Characterization using Pig Test . . . . . . 21 2.3.5 Shock Compression of Reactive Powder Mixtures...is to evaluate the reaction initiation characteristics of quasi-statically compressed intermetallic-forming aluminum-based reactive materials upon

Phospholipase A1-based cross-reactivity among venoms of clinically relevant Hymenoptera from Neotropical and temperate regions.

PubMed

Perez-Riverol, Amilcar; Fernandes, Luís Gustavo Romani; Musacchio Lasa, Alexis; Dos Santos-Pinto, José Roberto Aparecido; Moitinho Abram, Débora; Izuka Moraes, Gabriel Hideki; Jabs, Frederic; Miehe, Michaela; Seismman, Henning; Palma, Mario Sergio; de Lima Zollner, Ricardo; Spillner, Edzard; Brochetto-Braga, Márcia Regina

2018-01-01

Molecular cross-reactivity caused by allergen homology or cross-reactive carbohydrate determinants (CCDs) is a major challenge for diagnosis and immunotherapy of insect venom allergy. Venom phospholipases A1 (PLA1s) are classical, mostly non-glycosylated wasp and ant allergens that provide diagnostic benefit for differentiation of genuine sensitizations from cross-reactivity. As CCD-free molecules, venom PLA1s are not causative for CCD-based cross-reactivity. Little is known however about the protein-based cross-reactivity of PLA1 within vespid species. Here, we address PLA1-based cross-reactivity among ten clinically relevant Hymenoptera venoms from Neotropical and temperate regions including Polybia paulista (paulistinha) venom and Vespula vulgaris (yellow jacket) venom. In order to evaluate cross-reactivity, sera of mice sensitized with recombinant PLA1 (rPoly p 1) from P. paulista wasp venom were used. Pronounced IgE and IgG based cross-reactivity was detected for wasp venoms regardless the geographical region of origin. The cross-reactivity correlated well with the identity of the primary sequence and 3-D models of PLA1 proteins. In contrast, these mice sera showed no reaction with honeybee (HBV) and fire ant venom. Furthermore, sera from patients monosensitized to HBV and fire ants did not recognize the rPoly p 1 in immunoblotting. Our findings reveal the presence of conserved epitopes in the PLA1s from several clinically relevant wasps as major cause of PLA1-based in vitro cross-reactivity. These findings emphasize the limitations but also the potential of PLA1-based HVA diagnostics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recognition- and reactivity-based fluorescent probes for studying transition metal signaling in living systems.

PubMed

Aron, Allegra T; Ramos-Torres, Karla M; Cotruvo, Joseph A; Chang, Christopher J

2015-08-18

Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed "recognition" and "reactivity". Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give three recent examples from our laboratory and collaborations in which applications of chemical probes reveal that labile copper contributes to various physiologies. The first example shows that copper is an endogenous regulator of neuronal activity, the second illustrates cellular prioritization of mitochondrial copper homeostasis, and the third identifies the "cuprosome" as a new copper storage compartment in Chlamydomonas reinhardtii green algae. Indeed, recognition- and reactivity-based fluorescent probes have helped to uncover new biological roles for labile transition metals, and the further development of fluorescent probes, including ones with varied Kd values and new reaction triggers and recognition receptors, will continue to reveal exciting and new biological roles for labile transition metals.

Group versus individual stress management intervention in breast cancer patients for fatigue and emotional reactivity: a randomised intervention study.

PubMed

Rissanen, Ritva; Arving, Cecilia; Ahlgren, Johan; Nordin, Karin

2014-09-01

Fatigue and emotional reactivity are common among women suffering from breast cancer and might detrimentally affect these women's quality of life. This study evaluates if the stress management delivered either in a group or individual setting would improve fatigue and emotional reactivity among women with a newly diagnosed breast cancer. Participants (n = 304) who reported elevated levels of distress at three-month post-inclusion were randomised between stress management in a group (GSM) (n = 77) or individual (ISM) (n = 78) setting. Participation was declined by 149 women. Participants completed the Multidimensional Fatigue Inventory (MFI-20) and the Everyday Life Stress Scale (ELSS) at the time of inclusion, 3- and 12-month post-inclusion. Analyses were made according to intention to treat and per-protocol principles. Mann-Whitney tests were used to examine differences between the two intervention groups. No significant differences were detected between the GSM and ISM groups on fatigue or emotional reactivity. In addition, there were no changes over time for these outcomes. There were no differences between the two intervention arms with reference to fatigue or emotional reactivity; however, a clinically interesting finding was the low number of women who were interested in participating in a psychosocial intervention. This finding may have clinical implications when psychosocial support is offered to women with a newly diagnosed breast cancer and also in the planning of future studies.

Nine-analyte detection using an array-based biosensor

NASA Technical Reports Server (NTRS)

Taitt, Chris Rowe; Anderson, George P.; Lingerfelt, Brian M.; Feldstein, s. Mark. J.; Ligler, Frances S.

2002-01-01

A fluorescence-based multianalyte immunosensor has been developed for simultaneous analysis of multiple samples. While the standard 6 x 6 format of the array sensor has been used to analyze six samples for six different analytes, this same format has the potential to allow a single sample to be tested for 36 different agents. The method described herein demonstrates proof of principle that the number of analytes detectable using a single array can be increased simply by using complementary mixtures of capture and tracer antibodies. Mixtures were optimized to allow detection of closely related analytes without significant cross-reactivity. Following this facile modification of patterning and assay procedures, the following nine targets could be detected in a single 3 x 3 array: Staphylococcal enterotoxin B, ricin, cholera toxin, Bacillus anthracis Sterne, Bacillus globigii, Francisella tularensis LVS, Yersiniapestis F1 antigen, MS2 coliphage, and Salmonella typhimurium. This work maximizes the efficiency and utility of the described array technology, increasing only reagent usage and cost; production and fabrication costs are not affected.

A label-free immunoassay for Flavivirus detection by the Reflective Phantom Interface technology.

PubMed

Tagliabue, Giovanni; Faoro, Valentina; Rizzo, Serena; Sblattero, Daniele; Saccani, Andrea; Riccio, Gabriele; Bellini, Tommaso; Salina, Matteo; Buscaglia, Marco; Marcello, Alessandro

2017-10-28

Flaviviruses are widespread and cause clinically relevant arboviral diseases that impact locally and as imported travel-related infections. Direct detection of viraemia is limited, being typically undetectable at onset of symptoms. Therefore, diagnosis is primarily based on serology, which is complicated by high cross-reactivity across different species. The overlapping geographical distribution of the vectors in areas with a weak healthcare system, the increase of international travel and the similarity of symptoms highlight the need for rapid and reliable multi-parametric diagnostic tests in point-of-care formats. To this end we developed a bi-parametric serological microarray using recombinant NS1 proteins from Tick-borne encephalitis virus and West Nile virus coupled to a low-cost, label-free detection device based on the Reflective Phantom Interface (RPI) principle. Specific sequential detection of antibodies in solution demonstrates the feasibility of the approach for the surveillance and diagnosis of Flaviviruses. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of 3-bromopyruvate acid on the redox equilibrium in non-invasive MCF-7 and invasive MDA-MB-231 breast cancer cells.

PubMed

Kwiatkowska, Ewa; Wojtala, Martyna; Gajewska, Agnieszka; Soszyński, Mirosław; Bartosz, Grzegorz; Sadowska-Bartosz, Izabela

2016-02-01

Novel approaches to cancer chemotherapy employ metabolic differences between normal and tumor cells, including the high dependence of cancer cells on glycolysis ("Warburg effect"). 3-Bromopyruvate (3-BP), inhibitor of glycolysis, belongs to anticancer drugs basing on this principle. 3-BP was tested for its capacity to kill human non-invasive MCF-7 and invasive MDA-MB-231 breast cancer cells. We found that 3-BP was more toxic for MDA-MB-231 cells than for MCF-7 cells. In both cell lines, a statistically significant decrease of ATP and glutathione was observed in a time- and 3-BP concentration-dependent manner. Transient increases in the level of reactive oxygen species and reactive oxygen species was observed, more pronounced in MCF-7 cells, followed by a decreasing tendency. Activities of glutathione peroxidase, glutathione reductase (GR) and glutathione S-transferase (GST) decreased in 3-BP treated MDA-MB-231 cells. For MCF-7 cells decreases of GR and GST activities were noted only at the highest concentration of 3-BP.These results point to induction of oxidative stress by 3-BP via depletion of antioxidants and inactivation of antioxidant enzymes, more pronounced in MDA-MB-231 cells, more sensitive to 3-BP.

The ICCAM platform study: An experimental medicine platform for evaluating new drugs for relapse prevention in addiction. Part B: fMRI description

PubMed Central

McGonigle, John; Murphy, Anna; Paterson, Louise M; Reed, Laurence J; Nestor, Liam; Nash, Jonathan; Elliott, Rebecca; Ersche, Karen D; Flechais, Remy SA; Newbould, Rexford; Orban, Csaba; Smith, Dana G; Taylor, Eleanor M; Waldman, Adam D; Robbins, Trevor W; Deakin, JF William; Nutt, David J; Lingford-Hughes, Anne R; Suckling, John

2016-01-01

Objectives: We aimed to set up a robust multi-centre clinical fMRI and neuropsychological platform to investigate the neuropharmacology of brain processes relevant to addiction – reward, impulsivity and emotional reactivity. Here we provide an overview of the fMRI battery, carried out across three centres, characterizing neuronal response to the tasks, along with exploring inter-centre differences in healthy participants. Experimental design: Three fMRI tasks were used: monetary incentive delay to probe reward sensitivity, go/no-go to probe impulsivity and an evocative images task to probe emotional reactivity. A coordinate-based activation likelihood estimation (ALE) meta-analysis was carried out for the reward and impulsivity tasks to help establish region of interest (ROI) placement. A group of healthy participants was recruited from across three centres (total n=43) to investigate inter-centre differences. Principle observations: The pattern of response observed for each of the three tasks was consistent with previous studies using similar paradigms. At the whole brain level, significant differences were not observed between centres for any task. Conclusions: In developing this platform we successfully integrated neuroimaging data from three centres, adapted validated tasks and applied whole brain and ROI approaches to explore and demonstrate their consistency across centres. PMID:27703042

Molecular dynamics simulations of flame propagation along a monopropellant PETN coupled with multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Jain, S.; Mo, G.; Qiao, L.

2017-02-01

Reactive molecular dynamics simulations were conducted to study the flame speed enhancement phenomenon of a solid mono-propellant, Pentaerythritol Tetranitrate (PETN), when coupled to highly conductive multi-walled carbon nanotubes (MWCNTs). The simulations were based on the first-principles derived reactive force field, ReaxFF, which includes both the physical changes such as thermal transport and the chemical changes such as bond breaking and forming. An annular deposition of a PETN layer around the MWCNTs was considered. The thickness of the PETN layer and the diameter of the MWCNT were varied to understand the effect of the MWCNT loading ratio on the flame propagation. Flame speed enhancements up to 3 times the bulk value were observed. An optimal MWCNT loading ratio was determined. The enhancement was attributed to the layering of the PETN molecules around the MWCNT, which increased the heat transport among the PETN molecules near the MWCNT surface, thus causing the flame to travel faster. Furthermore, a stronger ignition source was required for the MWCNT-PETN complex because of the higher thermal transport among the PETN molecules along the MWCNT, which makes the ignition energy dissipate more quickly. Lastly, the MWCNT remained unburned during the PETN combustion process.

The ICCAM platform study: An experimental medicine platform for evaluating new drugs for relapse prevention in addiction. Part B: fMRI description.

PubMed

McGonigle, John; Murphy, Anna; Paterson, Louise M; Reed, Laurence J; Nestor, Liam; Nash, Jonathan; Elliott, Rebecca; Ersche, Karen D; Flechais, Remy Sa; Newbould, Rexford; Orban, Csaba; Smith, Dana G; Taylor, Eleanor M; Waldman, Adam D; Robbins, Trevor W; Deakin, Jf William; Nutt, David J; Lingford-Hughes, Anne R; Suckling, John

2017-01-01

We aimed to set up a robust multi-centre clinical fMRI and neuropsychological platform to investigate the neuropharmacology of brain processes relevant to addiction - reward, impulsivity and emotional reactivity. Here we provide an overview of the fMRI battery, carried out across three centres, characterizing neuronal response to the tasks, along with exploring inter-centre differences in healthy participants. Three fMRI tasks were used: monetary incentive delay to probe reward sensitivity, go/no-go to probe impulsivity and an evocative images task to probe emotional reactivity. A coordinate-based activation likelihood estimation (ALE) meta-analysis was carried out for the reward and impulsivity tasks to help establish region of interest (ROI) placement. A group of healthy participants was recruited from across three centres (total n=43) to investigate inter-centre differences. Principle observations: The pattern of response observed for each of the three tasks was consistent with previous studies using similar paradigms. At the whole brain level, significant differences were not observed between centres for any task. In developing this platform we successfully integrated neuroimaging data from three centres, adapted validated tasks and applied whole brain and ROI approaches to explore and demonstrate their consistency across centres.

Coatings with a Mole-hill Structure of Nanoparticle-Raspberry Containers for Surfaces with Abrasion-Refreshable Reservoir Functionality.

PubMed

Ballweg, Thomas; Gellermann, Carsten; Mandel, Karl

2015-11-11

Active silica nanoparticle-based raspberry-like container depots for agents such as antimicrobial substances are presented. The nano raspberry-containers are integrated into coatings in a way that they form a mole-hill structure; i.e., they are partly standing out of the coating. As an application example, it is demonstrated that the containers can be filled with antimicrobially active agents such as nano ZnO or Ag or organic molecules such as thymol. It is demonstrated that the containers can be partly chopped-off via abrasion by rubbing over the surface. This mechanism proves to be an attractive approach to render surfaces refreshable. A first proof of principle for antimicrobial activity of the intact containers in the coatings and the abrasion treated, chopped-off (and thereby reactivated) containers is demonstrated.

Oxidation of cefazolin by potassium permanganate: Transformation products and plausible pathways.

PubMed

Li, Liping; Wei, Dongbin; Wei, Guohua; Du, Yuguo

2016-04-01

Cefazolin was demonstrated to exert high reactivity toward permanganate (Mn(VII)), a common oxidant in water pre-oxidation treatment. In this study, five transformation products were found to be classified into three categories according to the contained characteristic functional groups: three (di-)sulfoxide products, one sulfone product and one di-ketone product. Products analyses showed that two kinds of reactions including oxidation of thioether and the cleavage of unsaturated CC double bond occurred during transformation of cefazolin by Mn(VII). Subsequently, the plausible transformation pathways under different pH conditions were proposed based on the identified products and chemical reaction principles. More importantly, the simulation with real surface water matrix indicated that the proposed transformation pathways of cefazolin could be replayed in real water treatment practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hit-and-run stimulation: a novel concept to reactivate latent HIV-1 infection without cytokine gene induction.

PubMed

Wolschendorf, Frank; Duverger, Alexandra; Jones, Jennifer; Wagner, Frederic H; Huff, Jason; Benjamin, William H; Saag, Michael S; Niederweis, Michael; Kutsch, Olaf

2010-09-01

Current antiretroviral therapy (ART) efficiently controls HIV-1 replication but fails to eradicate the virus. Even after years of successful ART, HIV-1 can conceal itself in a latent state in long-lived CD4(+) memory T cells. From this latent reservoir, HIV-1 rebounds during treatment interruptions. Attempts to therapeutically eradicate this viral reservoir have yielded disappointing results. A major problem with previously utilized activating agents is that at the concentrations required for efficient HIV-1 reactivation, these stimuli trigger high-level cytokine gene expression (hypercytokinemia). Therapeutically relevant HIV-1-reactivating agents will have to trigger HIV-1 reactivation without the induction of cytokine expression. We present here a proof-of-principle study showing that this is a possibility. In a high-throughput screening effort, we identified an HIV-1-reactivating protein factor (HRF) secreted by the nonpathogenic bacterium Massilia timonae. In primary T cells and T-cell lines, HRF triggered a high but nonsustained peak of nuclear factor kappa B (NF-kappaB) activity. While this short NF-kappaB peak potently reactivated latent HIV-1 infection, it failed to induce gene expression of several proinflammatory NF-kappaB-dependent cellular genes, such as those for tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8), and gamma interferon (IFN-gamma). Dissociation of cellular and viral gene induction was achievable, as minimum amounts of Tat protein, synthesized following application of a short NF-kappaB pulse, triggered HIV-1 transactivation and subsequent self-perpetuated HIV-1 expression. In the absence of such a positive feedback mechanism, cellular gene expression was not sustained, suggesting that strategies modulating the NF-kappaB activity profile could be used to selectively trigger HIV-1 reactivation.

First-Principles Monte Carlo Simulations of Reaction Equilibria in Compressed Vapors

PubMed Central

2016-01-01

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gas equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO2 and N2O in mole fractions approaching 1%, whereas N3 and O3 are not observed. The equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data. PMID:27413785

The physician Hans Reiter as prisoner of war in Nuremberg: a contextual review of his interrogations (1945-1947).

PubMed

Wallace, Daniel J; Weisman, Michael H

2003-02-01

Crimes against humanity by Nazi Germany led to the codification of procedures for trying medical professionals. The principles detailed in the Nuremberg Code formulated by the Allies represented their effort to prevent future excesses and embody today's Institutional Review Boards. Reactive arthritis is often termed Reiter's syndrome, after Hans Reiter, who was incarcerated at Nuremberg. The authors reviewed Dr Hans Reiter's Nuremberg file at the National Archives in Washington, DC, and present chronologic excerpts of his interrogations between 1945 and 1947, with interpretative commentary. Reiter was involved with or knowledgeable of involuntary sterilization and euthanasia undertaken by the Nazi regime. He also played an active role in the design of a study that inoculated concentration camp internees at Buchenwald with an experimental typhus vaccine, which resulted in hundreds of deaths. A brilliant investigator and erudite intellectual, the career of Hans Reiter shows the importance and the relevance of scientific inquiry to adhere to principles enumerated in the Nuremberg Code. Because he was not the first to describe reactive arthritis, and in view of the above, Reiter's syndrome should only be used to cite an older reference that uses the term or in a historical context. Copyright 2003, Elsevier Science (USA). All rights reserved.

Cognitive reactivity as outcome and working mechanism of mindfulness-based cognitive therapy for recurrently depressed patients in remission.

PubMed

Cladder-Micus, M B; van Aalderen, J; Donders, A R T; Spijker, J; Vrijsen, J N; Speckens, A E M

2018-03-01

Major depressive disorder is a prevalent condition with high relapse rates. There is evidence that cognitive reactivity is an important vulnerability factor for the recurrence of depression. Mindfulness-based interventions are designed to reduce relapse rates, with cognitive reactivity as one of the proposed working mechanisms. In a randomised controlled trial we compared the effect of mindfulness-based cognitive therapy (MBCT) with treatment-as-usual (TAU) on cognitive reactivity in recurrently depressed patients (N = 115). Depressive symptoms, cognitive reactivity, and mindfulness skills were assessed pre and post treatment. Patients in the MBCT group reported a significantly greater reduction in cognitive reactivity than those in the TAU group (d = .51). The reduction of cognitive reactivity appeared to mediate the association between MBCT/TAU and decrease of depressive symptoms, using pre and post scores. The current study provides evidence that MBCT reduces cognitive reactivity and preliminary evidence that cognitive reactivity is a working mechanism of MBCT.

Process-Based Mission Assurance- Knowledge Management System

NASA Astrophysics Data System (ADS)

Kantzes, Zachary S.; Wander, Stephen; Otero, Suzanne; Vantine, William; Stuart, Richard

2005-12-01

The Process-Based Mission Assurance - Knowledge Management System (PBMA-KMS) implemented at the National Aeronautics and Space Administration (NASA) focuses on the practical application of the knowledge management (KM) theory and is based on a systems engineering management approach coupled to a continual improvement and risk management philosophy. Not to be confused with an Agency mandate, an intense focus has been placed on grassroots input to the future of the product. By providing emphasis to both Agency safety and mission success objectives and individual users' needs, the PBMA-KMS team has been able to be both reactive to Agency requirements and proactive to the needs of the community.PBMA-KMS is an excellent case study on how to use new approaches to facilitate and integrate safety into the culture of an organization. Principle discussion topics include: • Overarching themes,• Tactical approaches,• Highlights of key functionalities, and• Agency KM approach of managed Darwinism.PBMA-KMS can show how, by providing top-level guidance along with the necessary tools and support, the organization not only receives immediate value, but the long-ranging benefits of a more experienced, effective, and engaged workforce.

Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Haipeng; Plawski, Tomasz E.; Rimmer, Robert A.

2016-06-01

Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve,more » output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen’s model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.« less

External Quality Control for Dried Blood Spot Based C-reactive Protein Assay: Experience from the Indonesia Family Life Survey and the Longitudinal Aging Study in India

PubMed Central

Hu, Peifeng; Herningtyas, Elizabeth H.; Kale, Varsha; Crimmins, Eileen M.; Risbud, Arun R.; McCreath, Heather; Lee, Jinkook; Strauss, John; O’Brien, Jennifer C.; Bloom, David E.; Seeman, Teresa E.

2015-01-01

Measurement of C-reactive protein, a marker of inflammation, in dried blood spots has been increasingly incorporated in community-based social surveys internationally. Although the dried blood spot based CRP assay protocol has been validated in the United States, it remains unclear whether laboratories in other less developed countries can generate C-reactive protein results of similar quality. We therefore conducted external quality monitoring for dried blood spot based C-reactive protein measurement for the Indonesia Family Life Survey and the Longitudinal Aging Study in India. Our results show that dried blood spot based C-reactive protein results in these two countries have excellent and consistent correlations with serum-based values and dried blood spot based results from the reference laboratory in the United States. Even though the results from duplicate samples may have fluctuations in absolute values over time, the relative order of C-reactive protein levels remains similar and the estimates are reasonably precise for population-based studies that investigate the association between socioeconomic factors and health. PMID:25879265

Stress reactivity and personality in extreme sport athletes: The psychobiology of BASE jumpers.

PubMed

Monasterio, Erik; Mei-Dan, Omer; Hackney, Anthony C; Lane, Amy R; Zwir, Igor; Rozsa, Sandor; Cloninger, C Robert

2016-12-01

This is the first report of the psychobiology of stress in BASE jumpers, one of the most dangerous forms of extreme sport. We tested the hypotheses that indicators of emotional style (temperament) predict salivary cortisol reactivity, whereas indicators of intentional goal-setting (persistence and character) predict salivary alpha-amylase reactivity during BASE jumping. Ninety-eight subjects completed the Temperament and Character Inventory (TCI) the day before the jump, and 77 also gave salivary samples at baseline, pre-jump on the bridge over the New River Gorge, and post-jump upon landing. Overall BASE jumpers are highly resilient individuals who are highly self-directed, persistent, and risk-taking, but they are heterogeneous in their motives and stress reactivity in the Hypothalamic-Pituitary-Adrenal (HPA) stress system (cortisol reactivity) and the sympathetic arousal system (alpha-amylase reactivity). Three classes of jumpers were identified using latent class analysis based on their personality profiles, prior jumping experience, and levels of cortisol and alpha-amylase at all three time points. "Masterful" jumpers (class 1) had a strong sense of self-directedness and mastery, extensive prior experience, and had little alpha-amylase reactivity and average cortisol reactivity. "Trustful" jumpers (class 2) were highly cooperative and trustful individuals who had little cortisol reactivity coincident with the social support they experienced prior to jumping. "Courageous" jumpers (class 3) were determined despite anxiety and inexperience, and they had high sympathetic reactivity but average cortisol activation. We conclude that trusting social attachment (Reward Dependence) and not jumping experience predicted low cortisol reactivity, whereas persistence (determination) and not jumping experience predicted high alpha-amylase reactivity. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Reactive Derivatives of Nucleic Acids and Their Components as Affinity Reagents

NASA Astrophysics Data System (ADS)

Knorre, Dmitrii G.; Vlasov, Valentin V.

1985-09-01

The review is devoted to derivatives of nucleic acids and their components — nucleotides, nucleoside triphosphates, and oligonucleotides carrying reactive groups. Such derivatives are important tools for the investigation of protein-nucleic acid interactions and the functional topography of complex protein and nucleoprotein structures and can give rise to the prospect of being able to influence in a highly selective manner living organisms, including the nucleic acids and the nucleoproteins of the genetic apparatus. The review considers the principal groups of such reagents, the methods of their synthesis, and their properties which determine the possibility of their use for the selective (affinity) modification of biopolymers. The general principles of the construction of affinity reagents and their applications are analysed in relation to nucleotide affinity reagents. The bibliography includes 121 references.

Reactive Monte Carlo sampling with an ab initio potential

DOE PAGES

Leiding, Jeff; Coe, Joshua D.

2016-05-04

Here, we present the first application of reactive Monte Carlo in a first-principles context. The algorithm samples in a modified NVT ensemble in which the volume, temperature, and total number of atoms of a given type are held fixed, but molecular composition is allowed to evolve through stochastic variation of chemical connectivity. We also discuss general features of the method, as well as techniques needed to enhance the efficiency of Boltzmann sampling. Finally, we compare the results of simulation of NH 3 to those of ab initio molecular dynamics (AIMD). Furthermore, we find that there are regions of state spacemore » for which RxMC sampling is much more efficient than AIMD due to the “rare-event” character of chemical reactions.« less

Expanded scope of training and education programs at the UFTR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vernetson, W.G.; Whaley, P.M.

1985-01-01

Historically, the University of Florida Training Reactor (UFTR) has been used to train both hot and cold license reactor operator candidates in intensive two- and three-week training programs consisting of a correlated set of classroom lectures, hands-on reactor operations, and laboratory exercises. These training programs provide nuclear plant operating staff with fundamental operational experience in understanding, controlling, and evaluating subcritical multiplication, reactivity effects, reactivity manipulations, and reactor operations; a sufficient number of startups and shutdowns is also assured. The UDTR is also used in a nuclear engineering course entitled ''Principles of Nuclear Reactor Operations.'' The purpose of this paper ismore » to report the results of efforts to redirect and refine tractor operations educational and training programs at the UFTR.« less

Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan.

PubMed

Lipp, Ilona; Murphy, Kevin; Caseras, Xavier; Wise, Richard G

2015-06-01

FMRI BOLD responses to changes in neural activity are influenced by the reactivity of the vasculature. By complementing a task-related BOLD acquisition with a vascular reactivity measure obtained through breath-holding or hypercapnia, this unwanted variance can be statistically reduced in the BOLD responses of interest. Recently, it has been suggested that vascular reactivity can also be estimated using a resting state scan. This study aimed to compare three breath-hold based analysis approaches (block design, sine-cosine regressor and CO2 regressor) and a resting state approach (CO2 regressor) to measure vascular reactivity. We tested BOLD variance explained by the model and repeatability of the measures. Fifteen healthy participants underwent a breath-hold task and a resting state scan with end-tidal CO2 being recorded during both. Vascular reactivity was defined as CO2-related BOLD percent signal change/mmHg change in CO2. Maps and regional vascular reactivity estimates showed high repeatability when the breath-hold task was used. Repeatability and variance explained by the CO2 trace regressor were lower for the resting state data based approach, which resulted in highly variable measures of vascular reactivity. We conclude that breath-hold based vascular reactivity estimations are more repeatable than resting-based estimates, and that there are limitations with replacing breath-hold scans by resting state scans for vascular reactivity assessment. Copyright © 2015. Published by Elsevier Inc.

Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan

PubMed Central

Lipp, Ilona; Murphy, Kevin; Caseras, Xavier; Wise, Richard G.

2015-01-01

FMRI BOLD responses to changes in neural activity are influenced by the reactivity of the vasculature. By complementing a task-related BOLD acquisition with a vascular reactivity measure obtained through breath-holding or hypercapnia, this unwanted variance can be statistically reduced in the BOLD responses of interest. Recently, it has been suggested that vascular reactivity can also be estimated using a resting state scan. This study aimed to compare three breath-hold based analysis approaches (block design, sine–cosine regressor and CO2 regressor) and a resting state approach (CO2 regressor) to measure vascular reactivity. We tested BOLD variance explained by the model and repeatability of the measures. Fifteen healthy participants underwent a breath-hold task and a resting state scan with end-tidal CO2 being recorded during both. Vascular reactivity was defined as CO2-related BOLD percent signal change/mm Hg change in CO2. Maps and regional vascular reactivity estimates showed high repeatability when the breath-hold task was used. Repeatability and variance explained by the CO2 trace regressor were lower for the resting state data based approach, which resulted in highly variable measures of vascular reactivity. We conclude that breath-hold based vascular reactivity estimations are more repeatable than resting-based estimates, and that there are limitations with replacing breath-hold scans by resting state scans for vascular reactivity assessment. PMID:25795342

Multimillion atom simulations of dynamics of oxidation of an aluminum nanoparticle and nanoindentation on ceramics.

PubMed

Vashishta, Priya; Kalia, Rajiv K; Nakano, Aiichiro

2006-03-02

We have developed a first-principles-based hierarchical simulation framework, which seamlessly integrates (1) a quantum mechanical description based on the density functional theory (DFT), (2) multilevel molecular dynamics (MD) simulations based on a reactive force field (ReaxFF) that describes chemical reactions and polarization, a nonreactive force field that employs dynamic atomic charges, and an effective force field (EFF), and (3) an atomistically informed continuum model to reach macroscopic length scales. For scalable hierarchical simulations, we have developed parallel linear-scaling algorithms for (1) DFT calculation based on a divide-and-conquer algorithm on adaptive multigrids, (2) chemically reactive MD based on a fast ReaxFF (F-ReaxFF) algorithm, and (3) EFF-MD based on a space-time multiresolution MD (MRMD) algorithm. On 1920 Intel Itanium2 processors, we have demonstrated 1.4 million atom (0.12 trillion grid points) DFT, 0.56 billion atom F-ReaxFF, and 18.9 billion atom MRMD calculations, with parallel efficiency as high as 0.953. Through the use of these algorithms, multimillion atom MD simulations have been performed to study the oxidation of an aluminum nanoparticle. Structural and dynamic correlations in the oxide region are calculated as well as the evolution of charges, surface oxide thickness, diffusivities of atoms, and local stresses. In the microcanonical ensemble, the oxidizing reaction becomes explosive in both molecular and atomic oxygen environments, due to the enormous energy release associated with Al-O bonding. In the canonical ensemble, an amorphous oxide layer of a thickness of approximately 40 angstroms is formed after 466 ps, in good agreement with experiments. Simulations have been performed to study nanoindentation on crystalline, amorphous, and nanocrystalline silicon nitride and silicon carbide. Simulation on nanocrystalline silicon carbide reveals unusual deformation mechanisms in brittle nanophase materials, due to coexistence of brittle grains and soft amorphous-like grain boundary phases. Simulations predict a crossover from intergranular continuous deformation to intragrain discrete deformation at a critical indentation depth.

TIMES-SS--recent refinements resulting from an industrial skin sensitisation consortium.

PubMed

Patlewicz, G; Kuseva, C; Mehmed, A; Popova, Y; Dimitrova, G; Ellis, G; Hunziker, R; Kern, P; Low, L; Ringeissen, S; Roberts, D W; Mekenyan, O

2014-01-01

The TImes MEtabolism Simulator platform for predicting Skin Sensitisation (TIMES-SS) is a hybrid expert system, first developed at Bourgas University using funding and data from a consortium of industry and regulators. TIMES-SS encodes structure-toxicity and structure-skin metabolism relationships through a number of transformations, some of which are underpinned by mechanistic 3D QSARs. The model estimates semi-quantitative skin sensitisation potency classes and has been developed with the aim of minimising animal testing, and also to be scientifically valid in accordance with the OECD principles for (Q)SAR validation. In 2007 an external validation exercise was undertaken to fully address these principles. In 2010, a new industry consortium was established to coordinate research efforts in three specific areas: refinement of abiotic reactions in the skin (namely autoxidation) in the skin, refinement of the manner in which chemical reactivity was captured in terms of structure-toxicity rules (inclusion of alert reliability parameters) and defining the domain based on the underlying experimental data (study of discrepancies between local lymph node assay Local Lymph Node Assay (LLNA) and Guinea Pig Maximisation Test (GPMT)). The present paper summarises the progress of these activities and explains how the insights derived have been translated into refinements, resulting in increased confidence and transparency in the robustness of the TIMES-SS predictions.

Unifying Model-Based and Reactive Programming within a Model-Based Executive

NASA Technical Reports Server (NTRS)

Williams, Brian C.; Gupta, Vineet; Norvig, Peter (Technical Monitor)

1999-01-01

Real-time, model-based, deduction has recently emerged as a vital component in AI's tool box for developing highly autonomous reactive systems. Yet one of the current hurdles towards developing model-based reactive systems is the number of methods simultaneously employed, and their corresponding melange of programming and modeling languages. This paper offers an important step towards unification. We introduce RMPL, a rich modeling language that combines probabilistic, constraint-based modeling with reactive programming constructs, while offering a simple semantics in terms of hidden state Markov processes. We introduce probabilistic, hierarchical constraint automata (PHCA), which allow Markov processes to be expressed in a compact representation that preserves the modularity of RMPL programs. Finally, a model-based executive, called Reactive Burton is described that exploits this compact encoding to perform efficIent simulation, belief state update and control sequence generation.

Permeable Reactive Zones for Groundwater Remediation

EPA Science Inventory

The presentation will cover aspects of the application of permeable reactive zones to treat contaminated ground water. Specific field studies will be discussed covering both granular iron-based and organic carbon-based reactive barriers. Specific contaminants addressed include:...

Reactivity-based industrial volatile organic compounds emission inventory and its implications for ozone control strategies in China

NASA Astrophysics Data System (ADS)

Liang, Xiaoming; Chen, Xiaofang; Zhang, Jiani; Shi, Tianli; Sun, Xibo; Fan, Liya; Wang, Liming; Ye, Daiqi

2017-08-01

Increasingly serious ozone (O3) pollution, along with decreasing NOx emission, is creating a big challenge in the control of volatile organic compounds (VOCs) in China. More efficient and effective measures are assuredly needed for controlling VOCs. In this study, a reactivity-based industrial VOCs emission inventory was established in China based on the concept of ozone formation potential (OFP). Key VOCs species, major VOCs sources, and dominant regions with high reactivity were identified. Our results show that the top 15 OFP-based species, including m/p-xylene, toluene, propene, o-xylene, and ethyl benzene, contribute 69% of the total OFP but only 30% of the total emission. The architectural decoration industry, oil refinery industry, storage and transport, and seven other sources constituted the top 10 OFP subsectors, together contributing a total of 85%. The provincial and spatial characteristics of OFP are generally consistent with those of mass-based inventory. The implications for O3 control strategies in China are discussed. We propose a reactivity-based national definition of VOCs and low-reactive substitution strategies, combined with evaluations of health risks. Priority should be given to the top 15 or more species with high reactivity through their major emission sources. Reactivity-based policies should be flexibly applied for O3 mitigation based on the sensitivity of O3 formation conditions.

Using Physical Organic Chemistry To Shape the Course of Electrochemical Reactions.

PubMed

Moeller, Kevin D

2018-05-09

While organic electrochemistry can look quite different to a chemist not familiar with the technique, the reactions are at their core organic reactions. As such, they are developed and optimized using the same physical organic chemistry principles employed during the development of any other organic reaction. Certainly, the electron transfer that triggers the reactions can require a consideration of new "wrinkles" to those principles, but those considerations are typically minimal relative to the more traditional approaches needed to manipulate the pathways available to the reactive intermediates formed downstream of that electron transfer. In this review, three very different synthetic challenges-the generation and trapping of radical cations, the development of site-selective reactions on microelectrode arrays, and the optimization of current in a paired electrolysis-are used to illustrate this point.

Does a higher metal oxidation state necessarily imply higher reactivity toward H-atom transfer? A computational study of C-H bond oxidation by high-valent iron-oxo and -nitrido complexes.

PubMed

Geng, Caiyun; Ye, Shengfa; Neese, Frank

2014-04-28

In this work, the reactions of C-H bond activation by two series of iron-oxo ( (Fe(IV)), (Fe(V)), (Fe(VI))) and -nitrido model complexes ( (Fe(IV)), (Fe(V)), (Fe(VI))) with a nearly identical coordination geometry but varying iron oxidation states ranging from iv to vi were comprehensively investigated using density functional theory. We found that in a distorted octahedral coordination environment, the iron-oxo species and their isoelectronic nitrido analogues feature totally different intrinsic reactivities toward C-H bond cleavage. In the case of the iron-oxo complexes, the reaction barrier monotonically decreases as the iron oxidation state increases, consistent with the gradually enhanced electrophilicity across the series. The iron-nitrido complex is less reactive than its isoelectronic iron-oxo species, and more interestingly, a counterintuitive reactivity pattern was observed, i.e. the activation barriers essentially remain constant independent of the iron oxidation states. The detailed analysis using the Polanyi principle demonstrates that the different reactivities between these two series originate from the distinct thermodynamic driving forces, more specifically, the bond dissociation energies (BDEE-Hs, E = O, N) of the nascent E-H bonds in the FeE-H products. Further decomposition of the BDEE-Hs into the electron and proton affinity components shed light on how the oxidation states modulate the BDEE-Hs of the two series.

[Telomerase activity in uveal melanomas].

PubMed

Rohrbach, J M; Riedinger, C; Wild, M; Partsch, M

2000-05-01

The maximum number of cell divisions of a certain cell population is genetically fixed so that aging cells become non-dividing (senescent) at least. This replicative life span, also known as "Hayflick limit", is probably defined by a "critical" length of the telomeres. Telomeres are special DNA-sequences located at the four ends of the chromosomes which are shortened with each cell cycle. Cells of most, but not all malignant tumours have been shown to reactivate the enzyme telomerase so that telomeres can be reconstructed, "Hayflick limit" can be overcome, and unlimited cell division can be established. This study was undertaken to elucidate whether telomerase reactivation is used by uveal melanoma cells. Fresh tumour tissue was removed from 10 untreated uveal melanomas after enucleation. Telomerase activity was determined using a PCR ELISA according to the Telomeric Repeat Amplification Protocol (TRAP). Normal tissue of the skin and the conjunctiva served as control. Telomerase activity was detectable in 90% of the investigated uveal melanomas. All control specimens were telomerase negative. Uveal melanoma growth seems to depend on telomerase reactivation. Thus, telomerase inhibition could offer a new principle for uveal melanoma therapy in the future.

Role of sulfonation in the stability, reactivity, and selectivity of poly(ether imide) used to develop ion exchange membranes: DFT study with application to fuel cells.

PubMed

López-Chávez, Ernesto; Peña-Castañeda, Yésica A; de la Portilla-Maldonado, L César; Guzmán-Pantoja, Javier; Martínez-Magadán, José Manuel; Oviedo-Roa, Raúl; de Landa Castillo-Alvarado, Fray; Cruz-Torres, Armando

2014-07-01

The design of polymer electrolyte membranes for fuel cells must satisfy two equally important fundamental principles: optimization of the reactivity and the selectivity in order to improve the ion transport properties of the membrane as well as its long-term stability in the hydrated state at high temperature (above 100 °C). A study utilizing density functional theory (DFT) to elucidate the effect of the degree of sulfonation on the chemical stability, reactivity, and selectivity of poly(ether imide) (PEI), which allows the ionic transport properties of the membrane to be predicted, is reported here. Sulfonated poly(ether imide) (SPEI) structures with (-SO3H) n (n = 1-6) groups were built and optimized in order to calculate the above properties as functions of the number of sulfonyl groups. A comparative study demonstrated that the SPEI with four sulfonyl groups in its backbone is the polymer with the properties best suited for use in fuel cells.

Global Ozone and Reactive Nitrogen : Composition, Chemistry and Sources

NASA Technical Reports Server (NTRS)

Sing, Hanwant B.; Bradshaw, J.; Davis, D.; Gregory, G.; Talbot, R.

1994-01-01

Ozone plays a central role in the chemistry of the atmosphere both as an ultraviolet shield and as a source of hydroxyl radicals (OH), a potent initiator of atmospheric chemistry. There is evidence to suggest that the ozone abundance in the troposphere (0-10 km) has doubled since the industrial revolution and continues to increase to date. The principle reason for this increase is thought to be the increasing emissions of nitrogen oxides (NO(x)) from anthropogenic activities. Although NO(x) is highly reactive and its products such as HN03 are easily removed by deposition, it now appears that its chemistry is quite complex and it can be transported over long distances via its conversion to a variety of nitrates and penetrates. The sources of atmospheric NO(x) include free tropospheric sources such as lightning and subsonic aircraft, as well as surface emissions which are transported to the free troposphere via convective processes. Recent experimental and theoretical studies have tried to unravel the chemistry of reactive nitrogen species, its sources, and their role in ozone formation. In this presentation we shall describe the results from these studies.

Tailoring the response of Autonomous Reactivity Control (ARC) systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qvist, Staffan A.; Hellesen, Carl; Gradecka, Malwina

The Autonomous Reactivity Control (ARC) system was developed to ensure inherent safety of Generation IV reactors while having a minimal impact on reactor performance and economic viability. In this study we present the transient response of fast reactor cores to postulated accident scenarios with and without ARC systems installed. Using a combination of analytical methods and numerical simulation, the principles of ARC system design that assure stability and avoids oscillatory behavior have been identified. A comprehensive transient analysis study for ARC-equipped cores, including a series of Unprotected Loss of Flow (ULOF) and Unprotected Loss of Heat Sink (ULOHS) simulations, weremore » performed for Argonne National Laboratory (ANL) Advanced Burner Reactor (ABR) designs. With carefully designed ARC-systems installed in the fuel assemblies, the cores exhibit a smooth non-oscillatory transition to stabilization at acceptable temperatures following all postulated transients. To avoid oscillations in power and temperature, the reactivity introduced per degree of temperature change in the ARC system needs to be kept below a certain threshold the value of which is system dependent, the temperature span of actuation needs to be as large as possible.« less

A Conceptual Model and Clinical Framework for Integrating Mindfulness into Family Therapy with Adolescents.

PubMed

Brody, Janet L; Scherer, David G; Turner, Charles W; Annett, Robert D; Dalen, Jeanne

2017-06-07

Individual and group-based psychotherapeutic interventions increasingly incorporate mindfulness-based principles and practices. These practices include a versatile set of skills such as labeling and attending to present-moment experiences, acting with awareness, and avoiding automatic reactivity. A primary motivation for integrating mindfulness into these therapies is compelling evidence that it enhances emotion regulation. Research also demonstrates that family relationships have a profound influence on emotion regulation capacities, which are central to family functioning and prosocial behavior more broadly. Despite this evidence, no framework exists to describe how mindfulness might integrate into family therapy. This paper describes the benefits of mindfulness-based interventions, highlighting how and why informal mindfulness practices might enhance emotion regulation when integrated with family therapy. We provide a clinical framework for integrating mindfulness into family therapy, particularly as it applies to families with adolescents. A brief case example details sample methods showing how incorporating mindfulness practices into family therapy may enhance treatment outcomes. A range of assessment modalities from biological to behavioral demonstrates the breadth with which the benefits of a family-based mindfulness intervention might be evaluated. © 2017 The Authors. Family Process published by Wiley Periodicals, Inc. on behalf of Family Process Institute.

Surface reactivity of mercury on the oxygen-terminated hematite(0001) surface: a first-principle study

NASA Astrophysics Data System (ADS)

Jung, J. E.; Wilcox, J.

2016-12-01

Hematite (α-Fe2O3) is a common mineral found in Earth's near-surface environment. Due to its nontoxicity, corrosion-resistance, and high thermal stability, α-Fe2O3 has attracted attentions as materials for various applications such as photocatalysts, gas sensors, as well as for the removal of heavy metals. In this study, α-Fe2O3 is chosen for potential mercury (Hg) sorbent in order to remove Hg from coal-fired power plants. Specifically, theoretical approaches using density functional theory (DFT) is used to understand surface reactivity of Hg on oxygen (O) terminated α-Fe2O3(0001) surface. The most probable adsorption sites of Hg, chlorine (Cl), and mercury chloride (HgCl) on the α-Fe2O3 surface are found based on adsorption energy calculations, and the oxidation states of the adsorbates are determined by Bader charge analysis. Additionally, projected density of states (PDOS) analysis characterizes the surface-adsorbate bonding mechanism. The results of adsorption energy calculation proposes that Hg physisorbs to the α-Fe2O3(0001) surface with adsorption energy of -0.278 eV, and the subsequent Bader charge analysis confirms that Hg is slightly oxidized. In addition, Cl introduced to the Hg-adsorbed surface strengthens Hg stability on the α-Fe2O3(0001) surface as evidenced by a shortened Hg-surface equilibrium distance. The PDOS analysis also suggests that Cl enhances the chemical bonding between the surface and the adsorbate, thereby increasing adsorption strength. In summary, α-Fe2O3 has ability to adsorb and oxidize Hg, and this reactivity is enhanced in the presence of Cl.

A novel attention training paradigm based on operant conditioning of eye gaze: Preliminary findings.

PubMed

Price, Rebecca B; Greven, Inez M; Siegle, Greg J; Koster, Ernst H W; De Raedt, Rudi

2016-02-01

Inability to engage with positive stimuli is a widespread problem associated with negative mood states across many conditions, from low self-esteem to anhedonic depression. Though attention retraining procedures have shown promise as interventions in some clinical populations, novel procedures may be necessary to reliably attenuate chronic negative mood in refractory clinical populations (e.g., clinical depression) through, for example, more active, adaptive learning processes. In addition, a focus on individual difference variables predicting intervention outcome may improve the ability to provide such targeted interventions efficiently. To provide preliminary proof-of-principle, we tested a novel paradigm using operant conditioning to train eye gaze patterns toward happy faces. Thirty-two healthy undergraduates were randomized to receive operant conditioning of eye gaze toward happy faces (train-happy) or neutral faces (train-neutral). At the group level, the train-happy condition attenuated sad mood increases following a stressful task, in comparison to train-neutral. In individual differences analysis, greater physiological reactivity (pupil dilation) in response to happy faces (during an emotional face-search task at baseline) predicted decreased mood reactivity after stress. These Preliminary results suggest that operant conditioning of eye gaze toward happy faces buffers against stress-induced effects on mood, particularly in individuals who show sufficient baseline neural engagement with happy faces. Eye gaze patterns to emotional face arrays may have a causal relationship with mood reactivity. Personalized medicine research in depression may benefit from novel cognitive training paradigms that shape eye gaze patterns through feedback. Baseline neural function (pupil dilation) may be a key mechanism, aiding in iterative refinement of this approach. (c) 2016 APA, all rights reserved).

Ad35 and Ad26 Vaccine Vectors Induce Potent and Cross-Reactive Antibody and T-Cell Responses to Multiple Filovirus Species

PubMed Central

Zahn, Roland; Gillisen, Gert; Roos, Anna; Koning, Marina; van der Helm, Esmeralda; Spek, Dirk; Weijtens, Mo; Grazia Pau, Maria; Radošević, Katarina; Weverling, Gerrit Jan; Custers, Jerome; Vellinga, Jort; Schuitemaker, Hanneke; Goudsmit, Jaap; Rodríguez, Ariane

2012-01-01

Filoviruses cause sporadic but highly lethal outbreaks of hemorrhagic fever in Africa in the human population. Currently, no drug or vaccine is available for treatment or prevention. A previous study with a vaccine candidate based on the low seroprevalent adenoviruses 26 and 35 (Ad26 and Ad35) was shown to provide protection against homologous Ebola Zaire challenge in non human primates (NHP) if applied in a prime-boost regimen. Here we have aimed to expand this principle to construct and evaluate Ad26 and Ad35 vectors for development of a vaccine to provide universal filovirus protection against all highly lethal strains that have caused major outbreaks in the past. We have therefore performed a phylogenetic analysis of filovirus glycoproteins to select the glycoproteins from two Ebola species (Ebola Zaire and Ebola Sudan/Gulu,), two Marburg strains (Marburg Angola and Marburg Ravn) and added the more distant non-lethal Ebola Ivory Coast species for broadest coverage. Ad26 and Ad35 vectors expressing these five filovirus glycoproteins were evaluated to induce a potent cellular and humoral immune response in mice. All adenoviral vectors induced a humoral immune response after single vaccination in a dose dependent manner that was cross-reactive within the Ebola and Marburg lineages. In addition, both strain-specific as well as cross-reactive T cell responses could be detected. A heterologous Ad26–Ad35 prime-boost regime enhanced mainly the humoral and to a lower extend the cellular immune response against the transgene. Combination of the five selected filovirus glycoproteins in one multivalent vaccine potentially elicits protective immunity in man against all major filovirus strains that have caused lethal outbreaks in the last 20 years. PMID:23236343

NHS-Esters As Versatile Reactivity-Based Probes for Mapping Proteome-Wide Ligandable Hotspots.

PubMed

Ward, Carl C; Kleinman, Jordan I; Nomura, Daniel K

2017-06-16

Most of the proteome is considered undruggable, oftentimes hindering translational efforts for drug discovery. Identifying previously unknown druggable hotspots in proteins would enable strategies for pharmacologically interrogating these sites with small molecules. Activity-based protein profiling (ABPP) has arisen as a powerful chemoproteomic strategy that uses reactivity-based chemical probes to map reactive, functional, and ligandable hotspots in complex proteomes, which has enabled inhibitor discovery against various therapeutic protein targets. Here, we report an alkyne-functionalized N-hydroxysuccinimide-ester (NHS-ester) as a versatile reactivity-based probe for mapping the reactivity of a wide range of nucleophilic ligandable hotspots, including lysines, serines, threonines, and tyrosines, encompassing active sites, allosteric sites, post-translational modification sites, protein interaction sites, and previously uncharacterized potential binding sites. Surprisingly, we also show that fragment-based NHS-ester ligands can be made to confer selectivity for specific lysine hotspots on specific targets including Dpyd, Aldh2, and Gstt1. We thus put forth NHS-esters as promising reactivity-based probes and chemical scaffolds for covalent ligand discovery.

Ultrafast dynamics in atomic clusters: Analysis and control

PubMed Central

Bonačić-Koutecký, Vlasta; Mitrić, Roland; Werner, Ute; Wöste, Ludger; Berry, R. Stephen

2006-01-01

We present a study of dynamics and ultrafast observables in the frame of pump–probe negative-to-neutral-to-positive ion (NeNePo) spectroscopy illustrated by the examples of bimetallic trimers Ag2Au−/Ag2Au/Ag2Au+ and silver oxides Ag3O2−/Ag3O2/Ag3O2+ in the context of cluster reactivity. First principle multistate adiabatic dynamics allows us to determine time scales of different ultrafast processes and conditions under which these processes can be experimentally observed. Furthermore, we present a strategy for optimal pump–dump control in complex systems based on the ab initio Wigner distribution approach and apply it to tailor laser fields for selective control of the isomerization process in Na3F2. The shapes of pulses can be assigned to underlying processes, and therefore control can be used as a tool for analysis. PMID:16740664

Ultrafast dynamics in atomic clusters: analysis and control.

PubMed

Bonacić-Koutecký, Vlasta; Mitrić, Roland; Werner, Ute; Wöste, Ludger; Berry, R Stephen

2006-07-11

We present a study of dynamics and ultrafast observables in the frame of pump-probe negative-to-neutral-to-positive ion (NeNePo) spectroscopy illustrated by the examples of bimetallic trimers Ag2Au-/Ag2Au/Ag2Au+ and silver oxides Ag3O2-/Ag3O2/Ag3O2+ in the context of cluster reactivity. First principle multistate adiabatic dynamics allows us to determine time scales of different ultrafast processes and conditions under which these processes can be experimentally observed. Furthermore, we present a strategy for optimal pump-dump control in complex systems based on the ab initio Wigner distribution approach and apply it to tailor laser fields for selective control of the isomerization process in Na3F2. The shapes of pulses can be assigned to underlying processes, and therefore control can be used as a tool for analysis.

Fluorescent sensors for the detection of chemical warfare agents.

PubMed

Burnworth, Mark; Rowan, Stuart J; Weder, Christoph

2007-01-01

Along with biological and nuclear threats, chemical warfare agents are some of the most feared weapons of mass destruction. Compared to nuclear weapons they are relatively easy to access and deploy, which makes them in some aspects a greater threat to national and global security. A particularly hazardous class of chemical warfare agents are the nerve agents. Their rapid and severe effects on human health originate in their ability to block the function of acetylcholinesterase, an enzyme that is vital to the central nervous system. This article outlines recent activities regarding the development of molecular sensors that can visualize the presence of nerve agents (and related pesticides) through changes of their fluorescence properties. Three different sensing principles are discussed: enzyme-based sensors, chemically reactive sensors, and supramolecular sensors. Typical examples are presented for each class and different fluorescent sensors for the detection of chemical warfare agents are summarized and compared.

Design and realization of assessment software for DC-bias of transformers

NASA Astrophysics Data System (ADS)

Liu, Chang; Liu, Lian-guang; Yuan, Zhong-chen

2013-03-01

The transformer working at the rated state will partically be saturated, and its mangetic current will be distorted accompanying with various of harmonic, increasing reactive power demand and some other affilicated phenomenon, which will threaten the safe operation of power grid. This paper establishes a transformer saturation circuit model of DCbias under duality principle basing on J-A theory which can reflect the hysteresis characteristics of iron core, and develops an software can assess the effects of transformer DC-bias using hybrid programming technology of C#.net and MATLAB with the microsoft.net platform. This software is able to simulate the mangnetizing current of different structures and assess the Saturation Level of transformers and the influnces of affilicated phenomenon accroding to the parameter of transformers and the DC equivalent voltage. It provides an effective method to assess the influnces of transformers caused by magnetic storm disaster and the earthing current of the HVDC project.

Hot-spot contributions in shocked high explosives from mesoscale ignition models

NASA Astrophysics Data System (ADS)

Levesque, G.; Vitello, P.; Howard, W. M.

2013-06-01

High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

NASA Astrophysics Data System (ADS)

Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

2017-01-01

The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

A spatially localized architecture for fast and modular DNA computing

NASA Astrophysics Data System (ADS)

Chatterjee, Gourab; Dalchau, Neil; Muscat, Richard A.; Phillips, Andrew; Seelig, Georg

2017-09-01

Cells use spatial constraints to control and accelerate the flow of information in enzyme cascades and signalling networks. Synthetic silicon-based circuitry similarly relies on spatial constraints to process information. Here, we show that spatial organization can be a similarly powerful design principle for overcoming limitations of speed and modularity in engineered molecular circuits. We create logic gates and signal transmission lines by spatially arranging reactive DNA hairpins on a DNA origami. Signal propagation is demonstrated across transmission lines of different lengths and orientations and logic gates are modularly combined into circuits that establish the universality of our approach. Because reactions preferentially occur between neighbours, identical DNA hairpins can be reused across circuits. Co-localization of circuit elements decreases computation time from hours to minutes compared to circuits with diffusible components. Detailed computational models enable predictive circuit design. We anticipate our approach will motivate using spatial constraints for future molecular control circuit designs.

Advances in quantifying air-sea gas exchange and environmental forcing.

PubMed

Wanninkhof, Rik; Asher, William E; Ho, David T; Sweeney, Colm; McGillis, Wade R

2009-01-01

The past decade has seen a substantial amount of research on air-sea gas exchange and its environmental controls. These studies have significantly advanced the understanding of processes that control gas transfer, led to higher quality field measurements, and improved estimates of the flux of climate-relevant gases between the ocean and atmosphere. This review discusses the fundamental principles of air-sea gas transfer and recent developments in gas transfer theory, parameterizations, and measurement techniques in the context of the exchange of carbon dioxide. However, much of this discussion is applicable to any sparingly soluble, non-reactive gas. We show how the use of global variables of environmental forcing that have recently become available and gas exchange relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea gas fluxes based on better fundamental physical, chemical, and biological foundations.

49 CFR Appendix E to Part 238 - General Principles of Reliability-Based Maintenance Programs

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false General Principles of Reliability-Based... STANDARDS Pt. 238, App. E Appendix E to Part 238—General Principles of Reliability-Based Maintenance... maintenance programs are based on the following general principles. A failure is an unsatisfactory condition...

Reactive trajectories of the Ru2+/3+ self-exchange reaction and the connection to Marcus' theory.

PubMed

Tiwari, Ambuj; Ensing, Bernd

2016-12-22

Outer sphere electron transfer between two ions in aqueous solution is a rare event on the time scale of first principles molecular dynamics simulations. We have used transition path sampling to generate an ensemble of reactive trajectories of the self-exchange reaction between a pair of Ru 2+ and Ru 3+ ions in water. To distinguish between the reactant and product states, we use as an order parameter the position of the maximally localised Wannier center associated with the transferring electron. This allows us to align the trajectories with respect to the moment of barrier crossing and compute statistical averages over the path ensemble. We compare our order parameter with two typical reaction coordinates used in applications of Marcus theory of electron transfer: the vertical gap energy and the solvent electrostatic potential at the ions.

Use of rhodamine B to mark the body and seminal fluid of male Aedes aegypti for mark-release-recapture experiments and estimating efficacy of sterile male releases

PubMed Central

Johnson, Brian J.; Mitchell, Sara N.; Paton, Christopher J.; Stevenson, Jessica; Staunton, Kyran M.; Snoad, Nigel; Beebe, Nigel; White, Bradley J.; Ritchie, Scott A.

2017-01-01

Background Recent interest in male-based sterile insect technique (SIT) and incompatible insect technique (IIT) to control Aedes aegypti and Aedes albopictus populations has revealed the need for an economical, rapid diagnostic tool for determining dispersion and mating success of sterilized males in the wild. Previous reports from other insects indicated rhodamine B, a thiol-reactive fluorescent dye, administered via sugar-feeding can be used to stain the body tissue and seminal fluid of insects. Here, we report on the adaptation of this technique for male Ae. aegypti to allow for rapid assessment of competitiveness (mating success) during field releases. Methodology/Principle findings Marking was achieved by feeding males on 0.1, 0.2, 0.4 or 0.8% rhodamine B (w/v) in 50% honey solutions during free flight. All concentrations produced >95% transfer to females and successful body marking after 4 days of feeding, with 0.4 and 0.8% solutions producing the longest-lasting body marking. Importantly, rhodamine B marking had no effect on male mating competitiveness and proof-of-principle field releases demonstrated successful transfer of marked seminal fluid to females under field conditions and recapture of marked males. Conclusions/Significance These results reveal rhodamine B to be a potentially useful evaluation method for male-based SIT/IIT control strategies as well as a viable body marking technique for male-based mark-release-recapture experiments without the negative side-effects of traditional marking methods. As a standalone method for use in mating competitiveness assays, rhodamine B marking is less expensive than PCR (e.g. paternity analysis) and stable isotope semen labelling methods and less time-consuming than female fertility assays used to assess competitiveness of sterilised males. PMID:28957318

First principles studies on anatase surfaces

NASA Astrophysics Data System (ADS)

Selcuk, Sencer

TiO2 is one of the most widely studied metal oxides from both the fundamental and the technological points of view. A variety of applications have already been developed in the fields of energy production, environmental remediation, and electronics. Still, it is considered to have a high potential for further improvement and continues to be of great interest. This thesis describes our theoretical studies on the structural and electronic properties of anatase surfaces, and their (photo)chemical behavior. Recently much attention has been focused on anatase crystals synthesized by hydrofluoric acid assisted methods. These crystals exhibit a high percentage of {001} facets, generally considered to be highly reactive. We used first principles methods to investigate the structure of these facets, which is not yet well understood. Our results suggest that (001) surfaces exhibit the bulk-terminated structure when in contact with concentrated HF solutions. However, 1x4-reconstructed surfaces, as observed in UHV, become always more stable at the typical temperatures used to clean the as-prepared crystals in experiments. Since the reconstructed surfaces are only weakly reactive, we predict that synthetic anatase crystals with dominant {001} facets should not exhibit enhanced photocatalytic activity. Understanding how defects in solids interact with external electric fields is important for technological applications such as memristor devices. We studied the influence of an external electric field on the formation energies and diffusion barriers of the surface and the subsurface oxygen vacancies at the anatase (101) surface from first principles. Our results show that the applied field can have a significant influence on the relative stabilities of these defects, whereas the effect on the subsurface-to-surface defect migration is found to be relatively minor. Charge carriers play a key role in the transport properties and the surface chemistry of TiO2. Understanding their behavior is essential for further improving the technologically relevant features of this material. We used first principles simulations to study the dynamical behavior of excess electrons near the anatase (101) and (001) surfaces, and their interfaces with water. Excess electrons prefer localizing on the (101) surface, also triggering water dissociation on this surface, while they strongly avoid the (001) surface.

A Novel Multiscale QM-MD-SPH Computational Method for Heterogeneous Multicomponent Reactive Systems

DTIC Science & Technology

2017-11-30

The first-principle study on the equation of state of hmx under high pressure. Science China Physics, Mechanics and Astronomy , 54(5):831–835, 2011...J J Monaghan, J C Lattanzio. A refined particle method for astrophysical problems. Astronomy and astrophysics 149 (1985): 135-143. 133 [148] J J...Monaghan. Smoothed particle hydrodynamics. Annual review of astronomy and astrophysics 30.1 (1992): 543-574. [149] J P Morris. A study of the

Cross-Electrophile Coupling: Principles of Reactivity and Selectivity

PubMed Central

2015-01-01

A critical overview of the catalytic joining of two different electrophiles, cross-electrophile coupling (XEC), is presented with an emphasis on the central challenge of cross-selectivity. Recent synthetic advances and mechanistic studies have shed light on four possible methods for overcoming this challenge: (1) employing an excess of one reagent; (2) electronic differentiation of starting materials; (3) catalyst–substrate steric matching; and (4) radical chain processes. Each method is described using examples from the recent literature. PMID:24820397

First-principles Monte Carlo simulations of reaction equilibria in compressed vapors

DOE PAGES

Fetisov, Evgenii O.; Kuo, I-Feng William; Knight, Chris; ...

2016-06-13

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gasmore » equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO 2 and N 2O in mole fractions approaching 1%, whereas N 3 and O 3 are not observed. Lastly, the equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data.« less

First-principles Monte Carlo simulations of reaction equilibria in compressed vapors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fetisov, Evgenii O.; Kuo, I-Feng William; Knight, Chris

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gasmore » equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO 2 and N 2O in mole fractions approaching 1%, whereas N 3 and O 3 are not observed. Lastly, the equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data.« less

Understanding the Reactive Adsorption of H 2S and CO 2 in Sodium-Exchanged Zeolites

DOE PAGES

Fetisov, Evgenii O.; Shah, Mansi S; Knight, Christopher; ...

2018-02-19

Purifying sour natural gas streams containing hydrogen sulfide and carbon dioxide has been a long-standing environmental and economic challenge. In the presence of cation-exchanged zeolites, these two acid gases can react to form carbonyl sulfide and water (H 2S+CO 2H 2O+COS), but this reaction is rarely accounted for. In this work, we carry out reactive first-principles Monte Carlo (RxFPMC) simulations for mixtures of H 2S and CO 2 in all-silica and Na-exchanged forms of zeolite beta to understand the governing principles driving the enhanced conversion. The RxFPMC simulations show that the presence of Na + cations can change the equilibriummore » constant by several orders of magnitude compared to the gas phase or in all-silica beta. The shift in the reaction equilibrium is caused by very strong interactions of H 2O with Na + that reduce the reaction enthalpy by about 20 kJmol -1. The simulations also demonstrate that the siting of Al atoms in the framework plays an important role. Lastly, the RxFPMC method presented here is applicable to any chemical conversion in any confined environment, where strong interactions of guest molecules with the host framework and high activation energies limit the use of other computational approaches to study reaction equilibria.« less

Reactive solute transport in physically and chemically heterogeneous porous media with multimodal reactive mineral facies: the Lagrangian approach.

PubMed

Soltanian, Mohamad Reza; Ritzi, Robert W; Dai, Zhenxue; Huang, Chao Cheng

2015-03-01

Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact of changing the mean, variance, and integral scale of K and Kd on reactive solute dispersion. Copyright © 2014 Elsevier Ltd. All rights reserved.

A structured policy review of the principles of professional self-regulation.

PubMed

Benton, D C; González-Jurado, M A; Beneit-Montesinos, J V

2013-03-01

The International Council of Nurses (ICN) has, for many years, based its work on professional self-regulation on a set of 12 principles. These principles are research based and were identified nearly three decades ago. ICN has conducted a number of reviews of the principles; however, changes have been minimal. In the past 5-10 years, a number of authors and governments, often as part of the review of regulatory systems, have started to propose principles to guide the way regulatory frameworks are designed and implemented. These principles vary in number and content. This study examines the current policy literature on principle-based regulation and compares this with the set of principles advocated by the ICN. A systematic search of the literature on principle-based regulation is used as the basis for a qualitative thematic analysis to compare and contrast the 12 principles of self-regulation with more recently published work. A mapping of terms based on a detailed description of the principles used in the various research and policy documents was generated. This mapping forms the basis of a critique of the current ICN principles. A professional self-regulation advocated by the ICN were identified. A revised and extended set of 13 principles is needed if contemporary developments in the field of regulatory frameworks are to be accommodated. These revised principles should be considered for adoption by the ICN to underpin their advocacy work on professional self-regulation. © 2013 The Authors. International Nursing Review © 2013 International Council of Nurses.

Structure of naturally hydrated ferrihydrite revealed through neutron diffraction and first-principles modeling

NASA Astrophysics Data System (ADS)

Chappell, Helen F.; Thom, William; Bowron, Daniel T.; Faria, Nuno; Hasnip, Philip J.; Powell, Jonathan J.

2017-08-01

Ferrihydrite, with a ``two-line'' x-ray diffraction pattern (2L-Fh), is the most amorphous of the iron oxides and is ubiquitous in both terrestrial and aquatic environments. It also plays a central role in the regulation and metabolism of iron in bacteria, algae, higher plants, and animals, including humans. In this study, we present a single-phase model for ferrihydrite that unifies existing analytical data while adhering to fundamental chemical principles. The primary particle is small (20-50 Å) and has a dynamic and variably hydrated surface, which negates long-range order; collectively, these features have hampered complete characterization and frustrated our understanding of the mineral's reactivity and chemical/biochemical function. Near and intermediate range neutron diffraction (NIMROD) and first-principles density functional theory (DFT) were employed in this study to generate and interpret high-resolution data of naturally hydrated, synthetic 2L-Fh at standard temperature. The structural optimization overcomes transgressions of coordination chemistry inherent within previously proposed structures, to produce a robust and unambiguous single-phase model.

Scalable electro-photonic integration concept based on polymer waveguides

NASA Astrophysics Data System (ADS)

Bosman, E.; Van Steenberge, G.; Boersma, A.; Wiegersma, S.; Harmsma, P.; Karppinen, M.; Korhonen, T.; Offrein, B. J.; Dangel, R.; Daly, A.; Ortsiefer, M.; Justice, J.; Corbett, B.; Dorrestein, S.; Duis, J.

2016-03-01

A novel method for fabricating a single mode optical interconnection platform is presented. The method comprises the miniaturized assembly of optoelectronic single dies, the scalable fabrication of polymer single mode waveguides and the coupling to glass fiber arrays providing the I/O's. The low cost approach for the polymer waveguide fabrication is based on the nano-imprinting of a spin-coated waveguide core layer. The assembly of VCSELs and photodiodes is performed before waveguide layers are applied. By embedding these components in deep reactive ion etched pockets in the silicon substrate, the planarity of the substrate for subsequent layer processing is guaranteed and the thermal path of chip-to-substrate is minimized. Optical coupling of the embedded devices to the nano-imprinted waveguides is performed by laser ablating 45 degree trenches which act as optical mirror for 90 degree deviation of the light from VCSEL to waveguide. Laser ablation is also implemented for removing parts of the polymer stack in order to mount a custom fabricated connector containing glass fiber arrays. A demonstration device was built to show the proof of principle of the novel fabrication, packaging and optical coupling principles as described above, combined with a set of sub-demonstrators showing the functionality of the different techniques separately. The paper represents a significant part of the electro-photonic integration accomplishments in the European 7th Framework project "Firefly" and not only discusses the development of the different assembly processes described above, but the efforts on the complete integration of all process approaches into the single device demonstrator.

The role of ethical principles in health care and the implications for ethical codes.

PubMed Central

Limentani, A E

1999-01-01

A common ethical code for everybody involved in health care is desirable, but there are important limitations to the role such a code could play. In order to understand these limitations the approach to ethics using principles and their application to medicine is discussed, and in particular the implications of their being prima facie. The expectation of what an ethical code can do changes depending on how ethical properties in general are understood. The difficulties encountered when ethical values are applied reactively to an objective world can be avoided by seeing them as a more integral part of our understanding of the world. It is concluded that an ethical code can establish important values and describe a common ethical context for health care but is of limited use in solving new and complex ethical problems. PMID:10536764

Recombinant antigen-based antibody assays for the diagnosis and surveillance of lymphatic filariasis – a multicenter trial

PubMed Central

Lammie, Patrick J; Weil, Gary; Noordin, Rahmah; Kaliraj, Perumal; Steel, Cathy; Goodman, David; Lakshmikanthan, Vijaya B; Ottesen, Eric

2004-01-01

The development of antifilarial antibody responses is a characteristic feature of infection with filarial parasites. It should be possible to exploit this fact to develop tools to monitor the progress of the global program to eliminate lymphatic filariasis (LF); however, assays based on parasite extracts suffer from a number of limitations, including the paucity of parasite material, the difficulty of assay standardization and problems with assay specificity. In principle, assays based on recombinant filarial antigens should address these limitations and provide useful tools for diagnosis and surveillance of LF. The present multicenter study was designed to compare the performance of antibody assays for filariasis based on recombinant antigens Bm14, WbSXP, and BmR1. Coded serum specimens were distributed to five participating laboratories where assays for each antigen were conducted in parallel. Assays based on Bm14, WbSXP, or BmR1 demonstrated good sensitivity (>90%) for field use and none of the assays demonstrated reactivity with specimens from persons with non-filarial helminth infections. Limitations of the assays are discussed. Well-designed field studies are now needed to assess sampling methodology and the application of antibody testing to the monitoring and surveillance of LF elimination programs. PMID:15347425

Reactive astrocytes and therapeutic potential in focal ischemic stroke

PubMed Central

Choudhury, Gourav Roy; Ding, Shinghua

2015-01-01

Astrocytes are specialized and the most abundant cell type in the central nervous system (CNS). They play important roles in the physiology of the brain. Astrocytes are also critically involved in many CNS disorders including focal ischemic stroke, the leading cause of brain injury and death in patients. One of the prominent pathological features of a focal ischemic stroke is reactive astrogliosis and glial scar formation. Reactive astrogliosis is accompanied with changes in morphology, proliferation and gene expression in the reactive astrocytes. This study provides an overview of the most recent advances in astrocytic Ca2+ signaling, spatial and temporal dynamics of the morphology and proliferation of reactive astrocytes as well as signaling pathways involved in the reactive astrogliosis after ischemic stroke based on results from experimental studies performed in various animal models. This review also discusses the therapeutic potential of reactive astrocytes in a focal ischemic stroke. As reactive astrocytes exhibit high plasticity, we suggest that modulation of local reactive astrocytes is a promising strategy for cell-based stroke therapy. PMID:25982835

Generic Software Architecture for Launchers

NASA Astrophysics Data System (ADS)

Carre, Emilien; Gast, Philippe; Hiron, Emmanuel; Leblanc, Alain; Lesens, David; Mescam, Emmanuelle; Moro, Pierre

2015-09-01

The definition and reuse of generic software architecture for launchers is not so usual for several reasons: the number of European launcher families is very small (Ariane 5 and Vega for these last decades); the real time constraints (reactivity and determinism needs) are very hard; low levels of versatility are required (implying often an ad hoc development of the launcher mission). In comparison, satellites are often built on a generic platform made up of reusable hardware building blocks (processors, star-trackers, gyroscopes, etc.) and reusable software building blocks (middleware, TM/TC, On Board Control Procedure, etc.). If some of these reasons are still valid (e.g. the limited number of development), the increase of the available CPU power makes today an approach based on a generic time triggered middleware (ensuring the full determinism of the system) and a centralised mission and vehicle management (offering more flexibility in the design and facilitating the long term maintenance) achievable. This paper presents an example of generic software architecture which could be envisaged for future launchers, based on the previously described principles and supported by model driven engineering and automatic code generation.

Suicide among war veterans.

PubMed

Rozanov, Vsevolod; Carli, Vladimir

2012-07-01

Studies aiming to identify if war veterans are at higher risk of suicide have often produced inconsistent results; this could be due to the complexity of comparisons and different methodological approaches. It should be noted that this contingent has many risk factors, such as stressful exposures, wounds, brain trauma and pain syndrome. Most recent observations confirm that veterans are really more likely to die of suicide as compared to the general population; they are also more likely to experience suicidal ideation and suffer from mental health problems. Suicides are more frequent in those who develop PTSD, depression and comorbid states due to war exposure. Combat stress and its' frequency may be an important factor leading to suicide within the frame of the stress-vulnerability model. According to this model, the effects of stress may interact with social factors, interpersonal relations and psychological variables producing suicidal tendencies. Modern understanding of stress-vulnerability mechanisms based on genetic predispositions, early life development, level of exposure to stress and stress-reactivity together with interpersonal aspects may help to build more effective suicide prevention programs based on universal/selective/indicated prevention principles.

Suicide among War Veterans

PubMed Central

Rozanov, Vsevolod; Carli, Vladimir

2012-01-01

Studies aiming to identify if war veterans are at higher risk of suicide have often produced inconsistent results; this could be due to the complexity of comparisons and different methodological approaches. It should be noted that this contingent has many risk factors, such as stressful exposures, wounds, brain trauma and pain syndrome. Most recent observations confirm that veterans are really more likely to die of suicide as compared to the general population; they are also more likely to experience suicidal ideation and suffer from mental health problems. Suicides are more frequent in those who develop PTSD, depression and comorbid states due to war exposure. Combat stress and its’ frequency may be an important factor leading to suicide within the frame of the stress-vulnerability model. According to this model, the effects of stress may interact with social factors, interpersonal relations and psychological variables producing suicidal tendencies. Modern understanding of stress-vulnerability mechanisms based on genetic predispositions, early life development, level of exposure to stress and stress-reactivity together with interpersonal aspects may help to build more effective suicide prevention programs based on universal/selective/indicated prevention principles. PMID:22851956

A MEMS SOI-based piezoresistive fluid flow sensor

NASA Astrophysics Data System (ADS)

Tian, B.; Li, H. F.; Yang, H.; Song, D. L.; Bai, X. W.; Zhao, Y. L.

2018-02-01

In this paper, a SOI (silicon-on-insulator)-based piezoresistive fluid flow sensor is presented; the presented flow sensor mainly consists of a nylon sensing head, stainless steel cantilever beam, SOI sensor chip, printed circuit board, half-cylinder gasket, and stainless steel shell. The working principle of the sensor and some detailed contrastive analysis about the sensor structure were introduced since the nylon sensing head and stainless steel cantilever beam have distinct influence on the sensor performance; the structure of nylon sensing head and stainless steel cantilever beam is also discussed. The SOI sensor chip was fabricated using micro-electromechanical systems technologies, such as reactive ion etching and low pressure chemical vapor deposition. The designed fluid sensor was packaged and tested; a calibration installation system was purposely designed for the sensor experiment. The testing results indicated that the output voltage of the sensor is proportional to the square of the fluid flow velocity, which is coincident with the theoretical derivation. The tested sensitivity of the sensor is 3.91 × 10-4 V ms2/kg.

Probing Aspergillus niger glucose oxidase with pentacyanoferrate(III) aza- and thia-complexes.

PubMed

Kulys, J; Tetianec, L; Ziemys, A

2006-10-01

Complexes of pentacyanoferrate(III) and biologically relevant ligands, such as pyridine, pyrazole, imidazole, histidine, and other aza- and thia-heterocycles, were synthesized. Their spectral, electrochemical properties, electron exchange constants, electronic structure parameters, and reactivity with glucose oxidase from Aspergillus niger were determined. The formation of the complexes following ammonia replacement by the ligands was associated with the appearance of a new band of absorbance in the visible spectrum. The constants of the complexes formation calculated at a ligand-pentacyanoferrate(III) concentrations ratio of 10:1, were 7.5 x 10(-5), 7.7 x 10(-5), and 1.8 x 10(-3) s(-1) for benzotriazole, benzimidazole, and aminothiazole ligands, respectively. The complexes showed quasi-reversible redox conversion at a glassy carbon electrode. The redox potential of the complexes spanned the potential range from 70 to 240 mV vs. saturated calomel electrode (SCE) at pH7.2. For most of the complexes self-exchange constants (k(11)) were similar to or larger than that of hexacyanoferrate(III) (ferricyanide). The complexes containing pyridine derivatives and thia-heterocyclic ligands held a lower value of k(11) than that of ferricyanide. All complexes reacted with reduced glucose oxidase at pH7.2. The reactivity of the complex containing pyrazole was the largest in comparison to the rest of the complexes. Correlations between the complexes' reactivity and both the free energy of reaction and k(11) shows that the reactivity of pentacyanoferrates obeys the principles of Marcus's electron transfer theory. The obtained data suggest that large negative charges of the complexes decrease their reactivity.

The Effect of the Local Delivery of Platelet-derived Growth Factor from Reactive Two-Component Polyurethane Scaffolds on the Healing in Rat Skin Excisional Wounds

PubMed Central

Li, Bing; Davidson, Jeffrey M.; Guelcher, Scott A.

2009-01-01

A key tenet of tissue engineering is the principle that the scaffold can perform the dual roles of biomechanical and biochemical support through presentation of the appropriate mediators to surrounding tissue. While growth factors have been incorporated into scaffolds to achieve sustained release, there are a limited number of studies investigating release of biologically active molecules from reactive two-component polymers, which have potential application as injectable delivery systems. In this study, we report the sustained release of platelet-derived growth factor (PDGF) from a reactive two-component polyurethane. The release of PDGF was bi-phasic, characterized by an initial burst followed by a period of sustained release for up to 21 days. Despite the potential for amine and hydroxyl groups in the protein to react with the isocyanate groups in the reactive polyurethane, the in vitro bioactivity of the released PDGF was largely preserved when added as a lyophilized powder. PUR/PDGF scaffolds implanted in rat skin excisional wounds accelerated wound healing relative to the blank PUR control, resulting in almost complete healing with reepithelization at day 14. The presence of PDGF attracted both fibroblasts and mononuclear cells, significantly accelerating degradation of the polymer and enhancing formation of new granulation tissue as early as day 3. The ability of reactive two-component PUR scaffolds to promote new tissue formation in vivo through local delivery of PDGF may present compelling opportunities for the development of novel injectable therapeutics. PMID:19328544

Cross-sectional population associations between detailed adiposity measures and C-reactive protein levels at age 6 years: the Generation R Study.

PubMed

Toemen, L; Gishti, O; Vogelezang, S; Gaillard, R; Hofman, A; Franco, O H; Felix, J F; Jaddoe, V W V

2015-07-01

High body mass index is associated with increased C-reactive protein levels in childhood and adulthood. Little is known about the associations of detailed adiposity measures with C-reactive protein levels in childhood. We examined the associations of general and abdominal adiposity measures with C-reactive protein levels at school age. To gain insight into the direction of causality, we used genetic risk scores based on known genetic variants in adults as proxies for child adiposity measures and C-reactive protein levels. Within a population-based cohort study among 4338 children at the median age of 6.2 years, we measured body mass index, fat mass percentage, android/gynoid fat mass ratio and preperitoneal abdominal fat mass. We also measured C-reactive protein blood levels and defined increased levels as ⩾3.0 mg l(-1). Single-nucleotide polymorphisms (SNPs) for the weighted genetic risk scores were extracted from large genome-wide association studies on adult body mass index, waist-hip ratio and C-reactive protein levels. All fat mass measures were associated with increased C-reactive protein levels, even after adjusting for multiple confounders. Fat mass percentage was most strongly associated with increased C-reactive protein levels (odds ratio 1.46 (95% confidence interval 1.30-1.65) per increase standard deviation scores in fat mass percentage). The association was independent of body mass index. The genetic risk score based on adult body mass index SNPs, but not adult waist-hip ratio SNPs, tended to be associated with increased C-reactive protein levels at school age. The genetic risk score based on adult C-reactive protein level SNPs was not associated with adiposity measures at school age. Our results suggest that higher general and abdominal fat mass may lead to increased C-reactive protein levels at school age. Further studies are needed to replicate these results and explore the causality and long-term consequences.

A theoretical study on the mechanism of hydrogen evolution on non-precious partially oxidized nickel-based heterostructures for fuel cells.

PubMed

Pan, Xinju; Zhou, Gang

2018-03-28

It is desirable, yet challenging, to utilize non-precious metals instead of noble-metals as efficient catalysts in the renewable energy manufacturing industry. Using first principles calculations, we study the structural characteristics of partially oxidized nickel-based nanoheterostructures (NiO/Ni NHSs), and the interfacial effects on hydrogen evolution. The origin of the enhanced hydrogen evolution performance is discussed at the microscopic level. This study identifies two types of active sites of the exposed Ni surface available for the hydrogen evolution reaction (HER). One is the hcp-hollow sites near the perimeter boundary that exhibit a more excellent HER performance than platinum (Pt), and the other the second nearest neighbor fcc-hollow sites away from the boundary that exhibit a similar performance to Pt. The interfacial effects result from the competitive charge transfer between NiO and Ni surfaces in NHSs, and enhance the reactivity of NiO/Ni NHSs by shifting the d-states of surface atoms down in energy. The illumination of the mechanism would be helpful for the design of more efficient and cheap transition metal-based catalysts.

Cooperative dual catalysis: application to the highly enantioselective conjugate cyanation of unsaturated imides.

PubMed

Sammis, Glenn M; Danjo, Hiroshi; Jacobsen, Eric N

2004-08-18

Cooperative heterobimetallic catalysis was used as a design principle to achieve a highly reactive system for the enantioselective conjugate addition of cyanide to alpha,beta-unsaturated imides. A dual-catalyst pathway involving chiral (salen)Al complex 1b and chiral (pybox)Er complex 4b provides measurable improvements in rates and enantioselectivities relative to single-catalyst systems. Mechanistic studies point to a cooperative bimetallic mechanism involving activation of the imide by the Al complex and activation of cyanide by the Er complex.

Prebiotic Synthesis of Autocatalytic Products From Formaldehyde-Derived Sugars as the Carbon and Energy Source

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

2003-01-01

Our research objective is to understand and model the chemical processes on the primitive Earth that generated the first autocatalytic molecules and microstructures involved in the origin of life. Our approach involves: (a) investigation of a model origin-of-life process named the Sugar Model that is based on the reaction of formaldehyde- derived sugars (trioses and tetroses) with ammonia, and (b) elucidation of the constraints imposed on the chemistry of the origin of life by the fixed energies and rates of C,H,O-organic reactions under mild aqueous conditions. Recently, we demonstrated that under mild aqueous conditions the Sugar Model process yields autocatalytic products, and generates organic micropherules (2-20 micron dia.) that exhibit budding, size uniformity, and chain formation. We also discovered that the sugar substrates of the Sugar Model are capable of reducing nitrite to ammonia under mild aqueous conditions. In addition studies done in collaboration with Sandra Pizzarrello (Arizona State University) revealed that chiral amino acids (including meteoritic isovaline) catalyze both the synthesis and specific handedness of chiral sugars. Our systematic survey of the energies and rates of reactions of C,H,O-organic substrates under mild aqueous conditions revealed several general principles (rules) that govern the direction and rate of organic reactions. These reactivity principles constrain the structure of chemical pathways used in the origin of life, and in modern and primitive metabolism.

Compression selective solid-state chemistry

NASA Astrophysics Data System (ADS)

Hu, Anguang

Compression selective solid-state chemistry refers to mechanically induced selective reactions of solids under thermomechanical extreme conditions. Advanced quantum solid-state chemistry simulations, based on density functional theory with localized basis functions, were performed to provide a remarkable insight into bonding pathways of high-pressure chemical reactions in all agreement with experiments. These pathways clearly demonstrate reaction mechanisms in unprecedented structural details, showing not only the chemical identity of reactive intermediates but also how atoms move along the reaction coordinate associated with a specific vibrational mode, directed by induced chemical stress occurred during bond breaking and forming. It indicates that chemical bonds in solids can break and form precisely under compression as we wish. This can be realized through strongly coupling of mechanical work to an initiation vibrational mode when all other modes can be suppressed under compression, resulting in ultrafast reactions to take place isothermally in a few femtoseconds. Thermodynamically, such reactions correspond to an entropy minimum process on an isotherm where the compression can force thermal expansion coefficient equal to zero. Combining a significantly brief reaction process with specific mode selectivity, both statistical laws and quantum uncertainty principle can be bypassed to precisely break chemical bonds, establishing fundamental principles of compression selective solid-state chemistry. Naturally this leads to understand the ''alchemy'' to purify, grow, and perfect certain materials such as emerging novel disruptive energetics.

Anticorrosive Effects of Some Thiophene Derivatives Against the Corrosion of Iron: A Computational Study

NASA Astrophysics Data System (ADS)

Guo, Lei; Safi, Zaki S.; Kaya, Savas; Shi, Wei; Tüzün, Burak; Altunay, Nail; Kaya, Cemal

2018-05-01

It is known that iron is one of the most widely used metals in industrial production. In this work, the inhibition performances of three thiophene derivatives on the corrosion of iron were investigated in the light of several theoretical approaches. In the section including DFT calculations, several global reactivity descriptors such as EHOMO, ELUMO, ionization energy (I), electron affinity (A), HOMO-LUMO energy gap (ΔE), chemical hardness (η), softness (σ), as well as local reactivity descriptors like Fukui indices, local softness, and local electrophilicity were considered and discussed. The adsorption behaviors of considered thiophene derivatives on Fe(110) surface were investigated using molecular dynamics simulation approach. To determine the most active corrosion inhibitor among studied thiophene derivatives, we used the principle component analysis (PCA) and agglomerative hierarchical cluster analysis (AHCA). Accordingly, all data obtained using various theoretical calculation techniques are consistent with experiments.

Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction.

PubMed

Coutinho, Nayara D; Silva, Valter H C; de Oliveira, Heibbe C B; Camargo, Ademir J; Mundim, Kleber C; Aquilanti, Vincenzo

2015-05-07

The OH + HBr → H2O + Br reaction, prototypical of halogen-atom liberating processes relevant to mechanisms for atmospheric ozone destruction, attracted frequent attention of experimental chemical kinetics: the nature of the unusual reactivity drop from low to high temperatures eluded a variety of theoretical efforts, ranking this one among the most studied four-atom reactions. Here, inspired by oriented molecular-beams experiments, we develop a first-principles stereodynamical approach. Thermalized sets of trajectories, evolving on a multidimensional potential energy surface quantum mechanically generated on-the-fly, provide a map of most visited regions at each temperature. Visualizations of rearrangements of bonds along trajectories and of the role of specific angles of reactants' mutual approach elucidate the mechanistic change from the low kinetic energy regime (where incident reactants reorient to find the propitious alignment leading to reaction) to high temperature (where speed hinders adjustment of directionality and roaming delays reactivity).

Scleroderma Autoantigens Are Uniquely Fragmented by Metal-catalyzed Oxidation Reactions: Implications for Pathogenesis

PubMed Central

Casciola-Rosen, Livia; Wigley, Fredrick; Rosen, Antony

1997-01-01

The observation that revelation of immunocryptic epitopes in self antigens may initiate the autoimmune response has prompted the search for processes which induce novel fragmentation of autoantigens as potential initiators of autoimmunity. The reversible ischemia reperfusion which characterizes scleroderma has focused attention on reactive oxygen species as molecules which might induce autoantigen fragmentation. We demonstrate that several of the autoantigens targeted in diffuse scleroderma are uniquely susceptible to cleavage by reactive oxygen species, in a metal-dependent manner. Multiple features of the fragmentation reaction and its inhibition indicate that these autoantigens possess metal-binding sites, which focus metal-catalyzed oxidation reactions (and consequent fragmentation) to specific regions of the antigens. These data suggest that the autoantibody response in scleroderma is the immune marker of unique protein fragmentation, induced by ischemia reperfusion in the presence of appropriate metals, and focus attention on abnormal metal status as a potential pathogenic principle in this disease. PMID:8996243

Using decision analysis to support proactive management of emerging infectious wildlife diseases

USGS Publications Warehouse

Grant, Evan H. Campbell; Muths, Erin L.; Katz, Rachel A.; Canessa, Stefano; Adams, Michael J.; Ballard, Jennifer R.; Berger, Lee; Briggs, Cheryl J.; Coleman, Jeremy; Gray, Matthew J.; Harris, M. Camille; Harris, Reid N.; Hossack, Blake R.; Huyvaert, Kathryn P.; Kolby, Jonathan E.; Lips, Karen R.; Lovich, Robert E.; McCallum, Hamish I.; Mendelson, Joseph R.; Nanjappa, Priya; Olson, Deanna H.; Powers, Jenny G.; Richgels, Katherine L. D.; Russell, Robin E.; Schmidt, Benedikt R.; Spitzen-van der Sluijs, Annemarieke; Watry, Mary Kay; Woodhams, Douglas C.; White, C. LeAnn

2017-01-01

Despite calls for improved responses to emerging infectious diseases in wildlife, management is seldom considered until a disease has been detected in affected populations. Reactive approaches may limit the potential for control and increase total response costs. An alternative, proactive management framework can identify immediate actions that reduce future impacts even before a disease is detected, and plan subsequent actions that are conditional on disease emergence. We identify four main obstacles to developing proactive management strategies for the newly discovered salamander pathogen Batrachochytrium salamandrivorans (Bsal). Given that uncertainty is a hallmark of wildlife disease management and that associated decisions are often complicated by multiple competing objectives, we advocate using decision analysis to create and evaluate trade-offs between proactive (pre-emergence) and reactive (post-emergence) management options. Policy makers and natural resource agency personnel can apply principles from decision analysis to improve strategies for countering emerging infectious diseases.

Diagrams for comprehensive molecular orbital-based chemical reaction analyses: reactive orbital energy diagrams.

PubMed

Tsuneda, Takao; Singh, Raman Kumar; Chattaraj, Pratim Kumar

2018-05-15

Reactive orbital energy diagrams are presented as a tool for comprehensively performing orbital-based reaction analyses. The diagrams rest on the reactive orbital energy theory, which is the expansion of conceptual density functional theory (DFT) to an orbital energy-based theory. The orbital energies on the intrinsic reaction coordinates of fundamental reactions are calculated by long-range corrected DFT, which is confirmed to provide accurate orbital energies of small molecules, combining with a van der Waals (vdW) correlation functional, in order to examine the vdW effect on the orbital energies. By analysing the reactions based on the reactive orbital energy theory using these accurate orbital energies, it is found that vdW interactions significantly affect the orbital energies in the initial reaction processes and that more than 70% of reactions are determined to be initially driven by charge transfer, while the remaining structural deformation (dynamics)-driven reactions are classified into identity, cyclization and ring-opening, unimolecular dissociation, and H2 reactions. The reactive orbital energy diagrams, which are constructed using these results, reveal that reactions progress so as to delocalize the occupied reactive orbitals, which are determined as contributing orbitals and are usually not HOMOs, by hybridizing the unoccupied reactive orbitals, which are usually not LUMOs. These diagrams also raise questions about conventional orbital-based diagrams such as frontier molecular orbital diagrams, even for the well-established interpretation of Diels-Alder reactions.

Quantum-state-resolved reactivity of overtone excited CH 4 on Ni(111): Comparing experiment and theory

DOE PAGES

Hundt, P. Morten; van Reijzen, Maarten E.; Beck, Rainer D.; ...

2017-02-07

Quantum state resolved reactivity measurements probe the role of vibrational symmetry on the vibrational activation of the dissociative chemisorption of CH 4 on Ni(111). IR-IR double resonance excitation in a molecular beam was used to prepare CH 4 in three different vibrational symmetry components A 1, E, and F 2 of the 2ν 32 antisymmetric stretch overtone vibration as well as in the ν1+ν3 symmetric plus antisymmetric C-H stretch combination band of F 2 symmetry. We measured the quantum state specific dissociation probability S 0 (sticking coefficient) for each of the four vibrational states by detecting chemisorbed carbon on Ni(111)more » as the product of CH 4 dissociation by Auger electron spectroscopy. We also observe strong mode specificity, where S 0 for the most reactive state ν 1+ν 3 is an order of magnitude higher than for the least reactive, more energetic 2ν 3-E state. Our first principles quantum scattering calculations show that as molecules in the ν1 state approach the surface, the vibrational amplitude becomes localized on the reacting C-H bond, making them very reactive. We found that this behavior results from the weakening of the reacting C-H bond as the molecule approaches the surface, decoupling its motion from the three non-reacting C-H stretches. Similarly, we find that overtone normal mode states with more ν 1 character are more reactive: S 0(2ν 1) > S 0(ν 1+ν 3) > S 0(2ν 3). The 2ν 3 eigenstates excited in the experiment can be written as linear combinations of these normal mode states. The highly reactive 2ν 1 and ν 1+ν 3 normal modes, being of A 1 and F 2 symmetry, can contribute to the 2ν 3-A 1 and 2ν 3-F 2 eigenstates, respectively, boosting their reactivity over the E component, which contains no ν 1 character due to symmetry.« less

In-situ study of beneficial utilization of coal fly ash in reactive mine tailings.

PubMed

Lee, Joon Kyu; Shang, Julie Q; Wang, Hongliu; Zhao, Cheng

2014-03-15

Oxidation of reactive mine tailings and subsequent generation of acid mine drainage (AMD) have been long recognized as the largest environmental concern for the mining industry. Laboratory studies on utilization of coal fly ash in management of reactive mine tailings have shown reducing water and oxygen infiltration into tailings matrix, thus preventing oxidation of sulphide minerals and acid generation. However, few data from field studies to evaluate the performance of co-placement of mine tailings and fly ash (CMF hereafter) are reported in the open literature. This paper documents the construction and instrumentation of three CMF systems on the Musselwhite mine located in Ontario, Canada and presents results of 3-year real time monitoring. The field data indicates that the CMFs reduced the ingress of water due to cementation generated by hydration of fly ash. It was also found that the electrical conductivity of leachate from CMFs decreased in the early stage of co-placement, compared to the control. With further study, the principle and approach demonstrated in this paper can be adopted as a sustainable technology in the mine tailings management. Copyright © 2014 Elsevier Ltd. All rights reserved.

Principles for identification of High Potency Category Chemicals for which the Dermal Sensitisation Threshold (DST) approach should not be applied.

PubMed

Roberts, David W; Api, Anne Marie; Safford, Robert J; Lalko, Jon F

2015-08-01

An essential step in ensuring the toxicological safety of chemicals used in consumer products is the evaluation of their skin sensitising potential. The sensitising potency, coupled with information on exposure levels, can be used in a Quantitative Risk Assessment (QRA) to determine an acceptable level of a given chemical in a given product. Where consumer skin exposure is low, a risk assessment can be conducted using the Dermal Sensitisation Threshold (DST) approach, avoiding the need to determine potency experimentally. Since skin sensitisation involves chemical reaction with skin proteins, the first step in the DST approach is to assess, on the basis of the chemical structure, whether the chemical is expected to be reactive or not. Our accompanying publication describes the probabilistic derivation of a DST of 64 μg/cm(2) for chemicals assessed as reactive. This would protect against 95% of chemicals assessed as reactive, but the remaining 5% would include chemicals with very high potency. Here we discuss the chemical properties and structural features of high potency sensitisers, and derive an approach whereby they can be identified and consequently excluded from application of the DST. Copyright © 2015 Elsevier Inc. All rights reserved.

The Principle-Based Method of Practical Ethics.

PubMed

Spielthenner, Georg

2017-09-01

This paper is about the methodology of doing practical ethics. There is a variety of methods employed in ethics. One of them is the principle-based approach, which has an established place in ethical reasoning. In everyday life, we often judge the rightness and wrongness of actions by their conformity to principles, and the appeal to principles plays a significant role in practical ethics, too. In this paper, I try to provide a better understanding of the nature of principle-based reasoning. To accomplish this, I show in the first section that these principles can be applied to cases in a meaningful and sufficiently precise way. The second section discusses the question how relevant applying principles is to the resolution of ethical issues. This depends on their nature. I argue that the principles under consideration in this paper should be interpreted as presumptive principles and I conclude that although they cannot be expected to bear the weight of definitely resolving ethical problems, these principles can nevertheless play a considerable role in ethical research.

Processes of change in a school-based mindfulness programme: cognitive reactivity and self-coldness as mediators.

PubMed

Van der Gucht, Katleen; Takano, Keisuke; Raes, Filip; Kuppens, Peter

2018-05-01

The underlying mechanisms of the effectiveness of mindfulness-based interventions for emotional well-being remain poorly understood. Here, we examined the potential mediating effects of cognitive reactivity and self-compassion on symptoms of depression, anxiety and stress using data from an earlier randomised controlled school trial. A moderated time-lagged mediation model based on multilevel modelling was used to analyse the data. The findings showed that post-treatment changes in cognitive reactivity and self-coldness, an aspect of self-compassion, mediated subsequent changes in symptoms of depression, anxiety and stress. These results suggest that cognitive reactivity and self-coldness may be considered as transdiagnostic mechanisms of change of a mindfulness-based intervention programme for youth.

Implementing Motivational Features in Reactive Blended Learning: Application to an Introductory Control Engineering Course

ERIC Educational Resources Information Center

Mendez, J. A.; Gonzalez, E. J.

2011-01-01

This paper presents a significant advance in a reactive blended learning methodology applied to an introductory control engineering course. This proposal was based on the inclusion of a reactive element (a fuzzy-logic-based controller) designed to regulate the workload for each student according to his/her activity and performance. The…

Adolescents’ Emotional Reactivity across Relationship Contexts

PubMed Central

Cook, Emily C.; Buehler, Cheryl; Blair, Bethany L.

2012-01-01

Adolescents’ emotional reactivity in family, close friendships, and romantic relationships was examined in a community-based sample of 416 two-parent families. Six waves of annual data were analyzed using structural equation modeling. Emotional reactivity to interparental conflict during early adolescence was associated prospectively with adolescents’ reactivity to conflict in friendships and romantic relationships during middle adolescence. Close friendship reactivity partially explained the prospective association between reactivity to interparental conflict and romantic relationship reactivity. The association between perceived emotional reactivity and relationship conflict was stronger for girls than boys. Results have important developmental implications regarding adolescents’ emotional reactivity across salient interpersonal contexts during adolescence. PMID:22545839

Prosthetic joint infection development of an evidence-based diagnostic algorithm.

PubMed

Mühlhofer, Heinrich M L; Pohlig, Florian; Kanz, Karl-Georg; Lenze, Ulrich; Lenze, Florian; Toepfer, Andreas; Kelch, Sarah; Harrasser, Norbert; von Eisenhart-Rothe, Rüdiger; Schauwecker, Johannes

2017-03-09

Increasing rates of prosthetic joint infection (PJI) have presented challenges for general practitioners, orthopedic surgeons and the health care system in the recent years. The diagnosis of PJI is complex; multiple diagnostic tools are used in the attempt to correctly diagnose PJI. Evidence-based algorithms can help to identify PJI using standardized diagnostic steps. We reviewed relevant publications between 1990 and 2015 using a systematic literature search in MEDLINE and PUBMED. The selected search results were then classified into levels of evidence. The keywords were prosthetic joint infection, biofilm, diagnosis, sonication, antibiotic treatment, implant-associated infection, Staph. aureus, rifampicin, implant retention, pcr, maldi-tof, serology, synovial fluid, c-reactive protein level, total hip arthroplasty (THA), total knee arthroplasty (TKA) and combinations of these terms. From an initial 768 publications, 156 publications were stringently reviewed. Publications with class I-III recommendations (EAST) were considered. We developed an algorithm for the diagnostic approach to display the complex diagnosis of PJI in a clear and logically structured process according to ISO 5807. The evidence-based standardized algorithm combines modern clinical requirements and evidence-based treatment principles. The algorithm provides a detailed transparent standard operating procedure (SOP) for diagnosing PJI. Thus, consistently high, examiner-independent process quality is assured to meet the demands of modern quality management in PJI diagnosis.

Integrated Lateral Flow Test Strip with Electrochemical Sensor for Quantification of Phosphorylated Cholinesterase: Biomarker of Exposure to Organophosphorus Agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Dan; Wang, Jun; Wang, Limin

An integrated lateral flow test strip with electrochemical sensor (LFTSES) device with rapid, selective and sensitive response for quantification of exposure to organophosphorus (OP) pesticides and nerve agents has been developed. The principle of this approach is based on parallel measurements of post-exposure and baseline acetylcholinesterase (AChE) enzyme activity, where reactivation of the phosphorylated AChE is exploited to enable measurement of total amount of AChE (including inhibited and active) which is used as a baseline for calculation of AChE inhibition. Quantitative measurement of phosphorylated adduct (OP-AChE) was realized by subtracting the active AChE from the total amount of AChE. Themore » proposed LFTSES device integrates immunochromatographic test strip technology with electrochemical measurement using a disposable screen printed electrode which is located under the test zone. It shows linear response between AChE enzyme activity and enzyme concentration from 0.05 to 10 nM, with detection limit of 0.02 nM. Based on this reactivation approach, the LFTSES device has been successfully applied for in vitro red blood cells inhibition studies using chlorpyrifos oxon as a model OP agent. This approach not only eliminates the difficulty in screening of low-dose OP exposure because of individual variation of normal AChE values, but also avoids the problem in overlapping substrate specificity with cholinesterases and avoids potential interference from other electroactive species in biological samples. It is baseline free and thus provides a rapid, sensitive, selective and inexpensive tool for in-field and point-of-care assessment of exposures to OP pesticides and nerve agents.« less

Potentiometric Sensors Based on Surface Molecular Imprinting: Detection of Cancer Biomarkers and Viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Y.; Zhang, Z; Jain, V

2010-01-01

The continuing discovery of cancer biomarkers necessitates improved methods for their detection. Molecular imprinting using artificial materials provides an alternative to the detection of a wide range of substances. We applied surface molecular imprinting using self-assembled monolayers to design sensing elements for the detection of cancer biomarkers and other proteins. These elements consist of a gold-coated silicon chip onto which hydroxyl-terminated alkanethiol molecules and template biomolecule are co-adsorbed, where the thiol molecules are chemically bound to the metal substrate and self-assembled into highly ordered monolayers, the biomolecules can be removed, creating the foot-print cavities in the monolayer matrix for thismore » kind of template molecules. Re-adsorption of the biomolecules to the sensing chip changes its potential, which can be measured potentiometrically. We applied this method to the detection of carcinoembryonic antigen (CEA) in both solutions of purified CEA and in the culture medium of a CEA-producing human colon cancer cell line. The CEA assay, validated also against a standard immunoassay, was both sensitive (detection range 2.5-250 ng/mL) and specific (no cross-reactivity with hemoglobin; no response by a non-imprinted sensor). Similar results were obtained for human amylase. In addition, we detected virions of poliovirus in a specific manner (no cross-reactivity to adenovirus, no response by a non-imprinted sensor). Our findings demonstrate the application of the principles of molecular imprinting to the development of a new method for the detection of protein cancer biomarkers and to protein-based macromolecular structures such as the capsid of a virion. This approach has the potential of generating a general assay methodology that could be highly sensitive, specific, simple and likely inexpensive.« less

Evaluation of the VIDAS Anti-HCV Assay for Detection of Hepatitis C Virus Infection.

PubMed

Hyun, Jungwon; Ko, Dae Hyun; Kang, Hee Jung; Whang, Dong Hee; Cha, Young Joo; Kim, Hyun Soo

2016-11-01

Anti-hepatitis C virus antibody (anti-HCV) assays are recommended for screening HCV-infected persons. The VIDAS Anti-HCV Assay (bioMérieux, France), based on the enzyme-linked fluorescence test principle, was recently introduced in Korea. We evaluated the clinical performance of the VIDAS assay. One hundred HCV-positive and 1,002 HCV-negative blood samples confirmed by Architect anti-HCV (Abbott Laboratories, USA) and COBAS TaqMan HCV real-time PCR (Roche Diagnostics, USA) or the Procleix Ultrio Plus Assay (Gen-Probe Incorporated, USA) were obtained from the Human Serum Bank (HSB) and tested by VIDAS. In case of discrepant results, we conducted a recombinant immunoblot assay (RIBA). The agreement rates for known HCV-positive and HCV-negative samples between the VIDAS assay and the HSB testing were 100% (95% confidence interval [CI]: 96.4-100%) and 99.5% (95% CI: 98.8-99.8%), respectively. One of the five discrepant samples was positive for Core 2+ and NS3-2 2+ reactivity, two samples were negative, and the other two were indeterminate regarding NS4 2+ reactivity in RIBA. We observed a significant but weak positive correlation between the titers of VIDAS and Architect assays (r=0.315, P<0.001). The VIDAS anti-HCV assay, developed on the VIDAS automated immunoassay platform based on the ready-to-use, single-sample test concept may be useful in small-to-medium-sized laboratories. It showed good agreement with Architect anti-HCV and COBAS PCR assays and is therefore useful for detection of HCV infection. Weakly test-positive (ambiguous) samples require additional testing by another anti-HCV, RIBA, or HCV RNA assay.

Evaluation of the VIDAS Anti-HCV Assay for Detection of Hepatitis C Virus Infection

PubMed Central

Hyun, Jungwon; Ko, Dae-Hyun; Kang, Hee Jung; Whang, Dong Hee

2016-01-01

Background Anti-hepatitis C virus antibody (anti-HCV) assays are recommended for screening HCV-infected persons. The VIDAS Anti-HCV Assay (bioMérieux, France), based on the enzyme-linked fluorescence test principle, was recently introduced in Korea. We evaluated the clinical performance of the VIDAS assay. Methods One hundred HCV-positive and 1,002 HCV-negative blood samples confirmed by Architect anti-HCV (Abbott Laboratories, USA) and COBAS TaqMan HCV real-time PCR (Roche Diagnostics, USA) or the Procleix Ultrio Plus Assay (Gen-Probe Incorporated, USA) were obtained from the Human Serum Bank (HSB) and tested by VIDAS. In case of discrepant results, we conducted a recombinant immunoblot assay (RIBA). Results The agreement rates for known HCV-positive and HCV-negative samples between the VIDAS assay and the HSB testing were 100% (95% confidence interval [CI]: 96.4-100%) and 99.5% (95% CI: 98.8-99.8%), respectively. One of the five discrepant samples was positive for Core 2+ and NS3-2 2+ reactivity, two samples were negative, and the other two were indeterminate regarding NS4 2+ reactivity in RIBA. We observed a significant but weak positive correlation between the titers of VIDAS and Architect assays (r=0.315, P<0.001). Conclusions The VIDAS anti-HCV assay, developed on the VIDAS automated immunoassay platform based on the ready-to-use, single-sample test concept may be useful in small-to-medium-sized laboratories. It showed good agreement with Architect anti-HCV and COBAS PCR assays and is therefore useful for detection of HCV infection. Weakly test-positive (ambiguous) samples require additional testing by another anti-HCV, RIBA, or HCV RNA assay. PMID:27578508

Forces and electronic transport in a contact formed by a graphene tip and a defective MoS2 monolayer: a theoretical study.

PubMed

di Felice, D; Dappe, Y J; González, C

2018-06-01

A theoretical study of a graphene-like tip used in atomic force microscopy (AFM) is presented. Based on first principles simulations, we proved the low reactivity of this kind of tip, using a MoS 2 monolayer as the testing sample. Our simulations show that the tip-MoS 2 interaction is mediated through weak van der Waals forces. Even on the defective monolayer, the interaction is reduced by one order of magnitude with respect to the values obtained using a highly reactive metallic tip. On the pristine monolayer, the S atoms were imaged for large distances together with the substitutional defects which should be observed as brighter spots in non-contact AFM measurements. This result is in contradiction with previous simulations performed with Cu or Si tips where the metallic defects were imaged for much larger distances than the S atoms. For shorter distances, the Mo sites will be brighter even though a vacancy is formed. On the other hand, the largest conductance value is obtained over the defect formed by two Mo atoms occupying a S divacancy when the half-occupied p y -states of the graphene-like tip find a better coupling with d-orbitals of the highest substitutional atom. Due to the weak interaction, no conductance plateau is formed in any of the sites. A great advantage of this tip lies in the absence of atomic transfer between the tip and the sample leading to a more stable AFM measurement. Finally, and as previously shown, we confirm the atomic resolution in a scanning tunneling microscopy simulation using this graphene-based tip.

Forces and electronic transport in a contact formed by a graphene tip and a defective MoS2 monolayer: a theoretical study

NASA Astrophysics Data System (ADS)

di Felice, D.; Dappe, Y. J.; González, C.

2018-06-01

A theoretical study of a graphene-like tip used in atomic force microscopy (AFM) is presented. Based on first principles simulations, we proved the low reactivity of this kind of tip, using a MoS2 monolayer as the testing sample. Our simulations show that the tip–MoS2 interaction is mediated through weak van der Waals forces. Even on the defective monolayer, the interaction is reduced by one order of magnitude with respect to the values obtained using a highly reactive metallic tip. On the pristine monolayer, the S atoms were imaged for large distances together with the substitutional defects which should be observed as brighter spots in non-contact AFM measurements. This result is in contradiction with previous simulations performed with Cu or Si tips where the metallic defects were imaged for much larger distances than the S atoms. For shorter distances, the Mo sites will be brighter even though a vacancy is formed. On the other hand, the largest conductance value is obtained over the defect formed by two Mo atoms occupying a S divacancy when the half-occupied p y -states of the graphene-like tip find a better coupling with d-orbitals of the highest substitutional atom. Due to the weak interaction, no conductance plateau is formed in any of the sites. A great advantage of this tip lies in the absence of atomic transfer between the tip and the sample leading to a more stable AFM measurement. Finally, and as previously shown, we confirm the atomic resolution in a scanning tunneling microscopy simulation using this graphene-based tip.

Development of a UNIX network compatible reactivity computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, R.F.; Edwards, R.M.

1996-12-31

A state-of-the-art UNIX network compatible controller and UNIX host workstation with MATLAB/SIMULINK software were used to develop, implement, and validate a digital reactivity calculation. An objective of the development was to determine why a Macintosh-based reactivity computer reactivity output drifted intolerably.

75 FR 71317 - Fundamental Principles and Policymaking Criteria for Partnerships With Faith-Based and Other...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-22

... Part IV The President Executive Order 13559--Fundamental Principles and Policymaking Criteria for... Fundamental Principles and Policymaking Criteria for Partnerships With Faith-Based and Other Neighborhood... the following: ``Sec. 2. Fundamental Principles. In formulating and implementing policies that have...

The surface stability and morphology of tobermorite 11 Å from first principles

NASA Astrophysics Data System (ADS)

Mutisya, Sylvia M.; Miranda, Caetano R.

2018-06-01

Tobermorite minerals are important in many industrial processes typically occurring in hydrous environment. Their functionality is therefore governed in various aspects by their morphology and surface stability/reactivity. Here, we present the results of the surface energies and morphology of normal tobermorite 11 Å in a water vapor environment investigated by employing first principles atomistic thermodynamic calculations. For the low index tobermorite surfaces studied, the calculated surface energies fall within a narrow range (0.41-0.97 J/m2) with the (0 0 4) surface being the most stable. The equilibrium morphology is a thin pseudohexagonal plate elongated along the b axis. The hydrated surfaces are more stable at high water vapor chemical potentials with the stability enhanced as the water partial pressures are varied from ambient to supercritical hydrothermal conditions. Increasing the water vapor chemical potential gives rise to a smaller size of the tobermorite crystal, with the equilibrium morphology remaining unaltered.

Predicted detonation properties at the Chapman-Jouguet state for proposed energetic materials (MTO and MTO3N) from combined ReaxFF and quantum mechanics reactive dynamics.

PubMed

Zhou, Tingting; Zybin, Sergey V; Goddard, William A; Cheng, Tao; Naserifar, Saber; Jaramillo-Botero, Andres; Huang, Fenglei

2018-02-07

The development of new energetic materials (EMs) with improved detonation performance but low sensitivity and environmental impact is of considerable importance for applications in civilian and military fields. Often new designs are difficult to synthesize so predictions of performance in advance is most valuable. Examples include MTO (2,4,6-triamino-1,3,5-triazine-1,3,5-trioxide) and MTO3N (2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxide) suggested by Klapötke as candidate EMs but not yet successfully synthesized. We propose and apply to these materials a new approach, RxMD(cQM), in which ReaxFF Reactive Molecular Dynamics (RxMD) is first used to predict the reaction products and thermochemical properties at the Chapman Jouguet (CJ) state for which the system is fully reacted and at chemical equilibrium. Quantum mechanics dynamics (QMD) is then applied to refine the pressure of the ReaxFF predicted CJ state to predict a more accurate final CJ point, leading to a very practical calculation that includes accurate long range vdW interactions needed for accurate pressure. For MTO, this RxMD(cQM) method predicts a detonation pressure of P CJ = 40.5 GPa and a detonation velocity of D CJ = 8.8 km s -1 , while for MTO3N it predicts P CJ = 39.9 GPa and D CJ = 8.4 km s -1 , making them comparable to HMX (P CJ = 39.5 GPa, D CJ = 9.1 km s -1 ) and worth synthesizing. This first-principles-based RxMD(cQM) methodology provides an excellent compromise between computational cost and accuracy including the formation of clusters that burn too slowly, providing a practical mean of assessing detonation performances for novel candidate EMs. This RxMD(cQM) method that links first principles atomistic molecular dynamics simulations with macroscopic properties to promote in silico design of new EMs should also be of general applicability to materials synthesis and processing.

Electronic properties and surface reactivity of SrO-terminated SrTiO3 and SrO-terminated iron-doped SrTiO3

PubMed Central

Staykov, Aleksandar; Tellez, Helena; Druce, John; Wu, Ji; Ishihara, Tatsumi; Kilner, John

2018-01-01

Abstract Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO3 and iron doped SrTiO3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO3 and compared it to DOS of iron-doped SrTiO3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO3 and iron-doped SrTiO3. Electron density plots and electron density distribution through the entire slab models were investigated in order to understand the origin of surface electrons that can participate in oxygen reduction reaction. Furthermore, we have compared oxygen reduction reactions at elevated temperatures for SrO surfaces with and without oxygen vacancies. Our calculations demonstrate that the conduction band, which is formed mainly by the d-states of Ti, and Fe-induced states within the band gap of SrTiO3, are accessible only on TiO2 terminated SrTiO3 surface while the SrO-terminated surface introduces a tunneling barrier for the electrons populating the conductance band. First principle molecular dynamics demonstrated that at elevated temperatures the surface oxygen vacancies are essential for the oxygen reduction reaction. PMID:29535797

The relationship between persuasive technology principles, adherence and effect of web-Based interventions for mental health: A meta-analysis.

PubMed

Wildeboer, Gina; Kelders, Saskia M; van Gemert-Pijnen, Julia E W C

2016-12-01

Research has shown that web-based interventions concerning mental health can be effective, although there is a broad range in effect sizes. Why some interventions are more effective than others is not clear. Persuasive technology is one of the aspects which has a positive influence on changing attitude and/or behavior, and can contribute to better outcomes. According to the Persuasive Systems Design Model there are various principles that can be deployed. It is unknown whether the number and combinations of principles used in a web-based intervention affect the effectiveness. Another issue in web-based interventions is adherence. Little is known about the relationship of adherence on the effectiveness of web-based interventions. This study examines whether there is a relationship between the number and combinations of persuasive technology principles used in web-based interventions and the effectiveness. Also the influence of adherence on effectiveness of web-based interventions is investigated. This study elaborates on the systematic review by [37] and therefore the articles were derived from that study. Only web-based interventions were included that were intended to be used on more than one occasion and studies were excluded when no information on adherence was provided. 48 interventions targeted at mental health were selected for the current study. A within-group (WG) and between-group (BG) meta-analysis were performed and subsequently subgroup analyses regarding the relationship between the number and combinations of persuasive technology principles and effectiveness. The influence of adherence on the effectiveness was examined through a meta-regression analysis. For the WG meta-analysis 40 treatment groups were included. The BG meta-analysis included 19 studies. The mean pooled effect size in the WG meta-analysis was large and significant (Hedges' g=0.94), while for the BG meta-analysis this was moderate to large and significant (Hedges' g=0.78) in favor of the web-based interventions. With regard to the number of persuasive technology principles, the differences between the effect sizes in the subgroups were significant in the WG subgroup analyses for the total number of principles and for the number of principles in the three categories Primary Task Support, Dialogue Support, and Social Support. In the BG subgroup analyses only the difference in Primary Task Support was significant. An increase in the total number of principles and Dialogue Support principles yielded larger effect sizes in the WG subgroup analysis, indicating that more principles lead to better outcomes. The number of principles in the Primary Task Support (WG and BG) and Social Support (WG) did not show an upward trend but had varying effect sizes. We identified a number of combinations of principles that were more effective, but only in the WG analyses. The association between adherence and effectiveness was not significant. There is a relationship between the number of persuasive technology principles and the effectiveness of web-based interventions concerning mental health, however this does not always mean that implementing more principles leads to better outcomes. Regarding the combinations of principles, specific principles seemed to work well together (e.g. tunneling and tailoring; reminders and similarity; social learning and comparison), but adding another principle can diminish the effectiveness (e.g. tunneling, tailoring and reduction). In this study, an increase in adherence was not associated with larger effect sizes. The findings of this study can help developers to decide which persuasive principles to include to make web-based interventions more persuasive. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Feasibility Study for the Use of Green, Bio-Based, Efficient Reactive Sorbent Material to Neutralize Chemical Warfare Agents

DTIC Science & Technology

2012-08-02

REPORT Feasibility study for the use of green, bio-based, efficient reactive sorbent material to neutralize chemical warfare agents 14. ABSTRACT 16...way cellulose, lignin and hemicelluloses interact as well as whole wood dissolution occurs in ILs. The present project was conducted to 1. REPORT...Feasibility study for the use of green, bio-based, efficient reactive sorbent material to neutralize chemical warfare agents Report Title ABSTRACT Over the

Consolidated principles for screening based on a systematic review and consensus process.

PubMed

Dobrow, Mark J; Hagens, Victoria; Chafe, Roger; Sullivan, Terrence; Rabeneck, Linda

2018-04-09

In 1968, Wilson and Jungner published 10 principles of screening that often represent the de facto starting point for screening decisions today; 50 years on, are these principles still the right ones? Our objectives were to review published work that presents principles for population-based screening decisions since Wilson and Jungner's seminal publication, and to conduct a Delphi consensus process to assess the review results. We conducted a systematic review and modified Delphi consensus process. We searched multiple databases for articles published in English in 1968 or later that were intended to guide population-based screening decisions, described development and modification of principles, and presented principles as a set or list. Identified sets were compared for basic characteristics (e.g., number, categorization), a citation analysis was conducted, and principles were iteratively synthesized and consolidated into categories to assess evolution. Participants in the consensus process assessed the level of agreement with the importance and interpretability of the consolidated screening principles. We identified 41 sets and 367 unique principles. Each unique principle was coded to 12 consolidated decision principles that were further categorized as disease/condition, test/intervention or program/system principles. Program or system issues were the focus of 3 of Wilson and Jungner's 10 principles, but comprised almost half of all unique principles identified in the review. The 12 consolidated principles were assessed through 2 rounds of the consensus process, leading to specific refinements to improve their relevance and interpretability. No gaps or missing principles were identified. Wilson and Jungner's principles are remarkably enduring, but increasingly reflect a truncated version of contemporary thinking on screening that does not fully capture subsequent focus on program or system principles. Ultimately, this review and consensus process provides a comprehensive and iterative modernization of guidance to inform population-based screening decisions. © 2018 Joule Inc. or its licensors.

Consolidated principles for screening based on a systematic review and consensus process

PubMed Central

Hagens, Victoria; Chafe, Roger; Sullivan, Terrence; Rabeneck, Linda

2018-01-01

BACKGROUND: In 1968, Wilson and Jungner published 10 principles of screening that often represent the de facto starting point for screening decisions today; 50 years on, are these principles still the right ones? Our objectives were to review published work that presents principles for population-based screening decisions since Wilson and Jungner’s seminal publication, and to conduct a Delphi consensus process to assess the review results. METHODS: We conducted a systematic review and modified Delphi consensus process. We searched multiple databases for articles published in English in 1968 or later that were intended to guide population-based screening decisions, described development and modification of principles, and presented principles as a set or list. Identified sets were compared for basic characteristics (e.g., number, categorization), a citation analysis was conducted, and principles were iteratively synthesized and consolidated into categories to assess evolution. Participants in the consensus process assessed the level of agreement with the importance and interpretability of the consolidated screening principles. RESULTS: We identified 41 sets and 367 unique principles. Each unique principle was coded to 12 consolidated decision principles that were further categorized as disease/condition, test/intervention or program/system principles. Program or system issues were the focus of 3 of Wilson and Jungner’s 10 principles, but comprised almost half of all unique principles identified in the review. The 12 consolidated principles were assessed through 2 rounds of the consensus process, leading to specific refinements to improve their relevance and interpretability. No gaps or missing principles were identified. INTERPRETATION: Wilson and Jungner’s principles are remarkably enduring, but increasingly reflect a truncated version of contemporary thinking on screening that does not fully capture subsequent focus on program or system principles. Ultimately, this review and consensus process provides a comprehensive and iterative modernization of guidance to inform population-based screening decisions. PMID:29632037

Ethical Virtues in Scientific Research

PubMed Central

Resnik, David B.

2012-01-01

Most approaches to promoting integrity in research are principle-based in that they portray ethical conduct as consisting of adherence to ethical rules, duties, or responsibilities. Bruce MacFarlane has recently criticized the principle-based approach to promoting integrity in research and offered a virtue-based alternative. MacFarlane argues that principle-based approaches do not provide adequate guidance for ethical decision-making and are not very useful in moral education. In this article, I examine and critique MacFarlane’s defense of the virtue-based approach. I argue that virtue-based and principle-based approaches to ethics are complementary and that they both can help promote research integrity. PMID:23074991

Ethical virtues in scientific research.

PubMed

Resnik, David B

2012-01-01

Most approaches to promoting integrity in research are principle-based in that they portray ethical conduct as consisting of adherence to ethical rules, duties, or responsibilities. Bruce MacFarlane has recently criticized the principle-based approach to promoting integrity in research and offered a virtue-based alternative. MacFarlane argues that principle-based approaches do not provide adequate guidance for ethical decision-making and are not very useful in moral education. In this article, I examine and critique MacFarlane's defense of the virtue-based approach. I argue that virtue-based and principle-based approaches to ethics are complementary and that they both can help promote research integrity.

Lithospheric controls on crustal reactivation and intraplate mountain building in the Gobi Corridor, Central Asia

NASA Astrophysics Data System (ADS)

Cunningham, D.

2017-12-01

This talk will review the Permian-Recent tectonic history of the Gobi Corridor region which includes the actively deforming Gobi Altai-Altai, Eastern Tien Shan, Beishan and North Tibetan foreland. Since terrane amalgamation in the Permian, Gobi Corridor crust has been repeatedly reactivated by Triassic-Jurassic contraction/transpression, Late Cretaceous extension and Late Cenozoic transpression. The tectonic history of the region suggests the following basic principle for intraplate continental regions: non-cratonized continental interior terrane collages are susceptible to repeated intraplate reactivation events, driven by either post-orogenic collapse and/or compressional stresses derived from distant plate boundary convergence. Thus, important related questions are: 1) what lithospheric pre-conditions favor intraplate crustal reactivation in the Gobi Corridor (simple answer: crustal thinning, thermal weakening, strong buttressing cratons), 2) what are the controls on the kinematics of deformation and style of mountain building in the Gobi-Altai-Altai, Beishan and North Tibetan margin (simple answer: many factors, but especially angular relationship between SHmax and `crustal grain'), 3) how does knowledge of the array of Quaternary faults and the historical earthquake record influence our understanding of modern earthquake hazards in continental intraplate regions (answer: extrapolation of derived fault slip rates and recurrence interval determinations are problematic), 4) what important lessons can we learn from the Mesozoic-Cenozoic tectonic history of Central Asia that is applicable to the tectonic evolution of all intraplate continental regions (simple answer: ancient intraplate deformation events may be subtly expressed in the rock record and only revealed by low-temperature thermochronometers, preserved orogen-derived sedimentary sequences, fault zone evidence for younger brittle reactivation, and recognition of a younger class of cross-cutting tectonic structures).

Proof-of-Principle for Immune Control of Global HIV-1 Reactivation In Vivo

PubMed Central

Smith, Nicola M. G.; Mlcochova, Petra; Watters, Sarah A.; Aasa-Chapman, Marlene M. I.; Rabin, Neil; Moore, Sally; Edwards, Simon G.; Garson, Jeremy A.; Grant, Paul R.; Ferns, R. Bridget; Kashuba, Angela; Mayor, Neema P.; Schellekens, Jennifer; Marsh, Steven G. E.; McMichael, Andrew J.; Perelson, Alan S.; Pillay, Deenan; Goonetilleke, Nilu; Gupta, Ravindra K.

2015-01-01

Background. Emerging data relating to human immunodeficiency virus type 1 (HIV-1) cure suggest that vaccination to stimulate the host immune response, particularly cytotoxic cells, may be critical to clearing of reactivated HIV-1–infected cells. However, evidence for this approach in humans is lacking, and parameters required for a vaccine are unknown because opportunities to study HIV-1 reactivation are rare. Methods. We present observations from a HIV-1 elite controller, not treated with combination antiretroviral therapy, who experienced viral reactivation following treatment for myeloma with melphalan and autologous stem cell transplantation. Mathematical modeling was performed using a standard viral dynamic model. Enzyme-linked immunospot, intracellular cytokine staining, and tetramer staining were performed on peripheral blood mononuclear cells; in vitro CD8 T-cell–mediated control of virion production by autologous CD4 T cells was quantified; and neutralizing antibody titers were measured. Results. Viral rebound was measured at 28 000 copies/mL on day 13 post-transplant before rapid decay to <50 copies/mL in 2 distinct phases with t1/2 of 0.71 days and 4.1 days. These kinetics were consistent with an expansion of cytotoxic effector cells and killing of productively infected CD4 T cells. Following transplantation, innate immune cells, including natural killer cells, recovered with virus rebound. However, most striking was the expansion of highly functional HIV-1–specific cytotoxic CD8 T cells, at numbers consistent with those applied in modeling, as virus control was regained. Conclusions. These observations provide evidence that the human immune response is capable of controlling coordinated global HIV-1 reactivation, remarkably with potency equivalent to combination antiretroviral therapy. These data will inform design of vaccines for use in HIV-1 curative interventions. PMID:25778749

Triazine dyes are agonists of the NAADP receptor

PubMed Central

Billington, Richard A; Bak, Judit; Martinez-Coscolla, Ana; Debidda, Marcella; Genazzani, Armando A

2004-01-01

NAADP has been shown to be a potent calcium-releasing second messenger in a wide variety of cell types to date. However, research has been hampered by a lack of pharmacological agents, with which to investigate NAADP-induced calcium release, and by the molecular identity of its cellular target protein being unknown.In the present paper, the sea urchin egg model was used to investigate whether triazine dyes, which can act as nucleotide mimetics, can bind to the NAADP receptor, induce Ca2+ release and be used for affinity chromatography of the receptor.Indeed, all the triazine dyes tested (Reactive Red 120 (RR120), Reactive Green 19 (RG19), Reactive Green 5 (RG5), Cibacron Blue 3GA and Reactive Yellow 86) displayed micromolar affinities, except for Reactive Orange 14. Furthermore, unlike NAADP, RR120, RG19 and RG5 did not bind in an irreversible manner.The compound that displayed the highest affinity, RR120, was tested in a 45Ca2+ efflux assay. This compound released Ca2+ via the NAADP receptor, as shown by the ability of subthreshold NAADP concentrations to inhibit this release. Furthermore, heparin and ruthenium red were unable to block RR120-induced Ca2+ release.We have also shown that RG5 and RG19, immobilised on resins, retain the ability to bind to the receptor, and that this interaction can be disrupted by high salt concentrations. As a proof of principle, we have shown that this can be used to partially purify the NAADP receptor by at least 75-fold.In conclusion, triazine dyes interact with the NAADP receptor, and this could be exploited in future to create a new generation of pharmacological tools to investigate this messenger and, in combination with other techniques, to purify the receptor. PMID:15265807

SeSBench - An initiative to benchmark reactive transport models for environmental subsurface processes

NASA Astrophysics Data System (ADS)

Jacques, Diederik

2017-04-01

As soil functions are governed by a multitude of interacting hydrological, geochemical and biological processes, simulation tools coupling mathematical models for interacting processes are needed. Coupled reactive transport models are a typical example of such coupled tools mainly focusing on hydrological and geochemical coupling (see e.g. Steefel et al., 2015). Mathematical and numerical complexity for both the tool itself or of the specific conceptual model can increase rapidly. Therefore, numerical verification of such type of models is a prerequisite for guaranteeing reliability and confidence and qualifying simulation tools and approaches for any further model application. In 2011, a first SeSBench -Subsurface Environmental Simulation Benchmarking- workshop was held in Berkeley (USA) followed by four other ones. The objective is to benchmark subsurface environmental simulation models and methods with a current focus on reactive transport processes. The final outcome was a special issue in Computational Geosciences (2015, issue 3 - Reactive transport benchmarks for subsurface environmental simulation) with a collection of 11 benchmarks. Benchmarks, proposed by the participants of the workshops, should be relevant for environmental or geo-engineering applications; the latter were mostly related to radioactive waste disposal issues - excluding benchmarks defined for pure mathematical reasons. Another important feature is the tiered approach within a benchmark with the definition of a single principle problem and different sub problems. The latter typically benchmarked individual or simplified processes (e.g. inert solute transport, simplified geochemical conceptual model) or geometries (e.g. batch or one-dimensional, homogeneous). Finally, three codes should be involved into a benchmark. The SeSBench initiative contributes to confidence building for applying reactive transport codes. Furthermore, it illustrates the use of those type of models for different environmental and geo-engineering applications. SeSBench will organize new workshops to add new benchmarks in a new special issue. Steefel, C. I., et al. (2015). "Reactive transport codes for subsurface environmental simulation." Computational Geosciences 19: 445-478.

Adaptive Q–V Scheme for the Voltage Control of a DFIG-Based Wind Power Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jinho; Seok, Jul-Ki; Muljadi, Eduard

Wind generators within a wind power plant (WPP) will produce different amounts of active power because of the wake effect, and therefore, they have different reactive power capabilities. This paper proposes an adaptive reactive power to the voltage (Q-V) scheme for the voltage control of a doubly fed induction generator (DFIG)-based WPP. In the proposed scheme, the WPP controller uses a voltage control mode and sends a voltage error signal to each DFIG. The DFIG controller also employs a voltage control mode utilizing the adaptive Q-V characteristics depending on the reactive power capability such that a DFIG with a largermore » reactive power capability will inject more reactive power to ensure fast voltage recovery. Test results indicate that the proposed scheme can recover the voltage within a short time, even for a grid fault with a small short-circuit ratio, by making use of the available reactive power of a WPP and differentiating the reactive power injection in proportion to the reactive power capability. This will, therefore, help to reduce the additional reactive power and ensure fast voltage recovery.« less

IMPULSIVE SPOT HEATING AND THERMAL EXPLOSION OF INTERSTELLAR GRAINS REVISITED

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivlev, A. V.; Röcker, T. B.; Vasyunin, A.

The problem of the impulsive heating of dust grains in cold, dense interstellar clouds is revisited theoretically with the aim of better understanding the leading mechanisms of the explosive desorption of icy mantles. We rigorously show that if the heating of a reactive medium occurs within a sufficiently localized spot (e.g., the heating of mantles by cosmic rays (CRs)), then the subsequent thermal evolution is characterized by a single dimensionless number λ. This number identifies a bifurcation between two distinct regimes: when λ exceeds a critical value (threshold), the heat equation exhibits the explosive solution, i.e., the thermal (chemical) explosionmore » is triggered. Otherwise, thermal diffusion causes the deposited heat to spread over the entire grain—this regime is commonly known as whole-grain heating. The theory allows us to find a critical combination of physical parameters that govern the explosion of icy mantles due to impulsive spot heating. In particular, our calculations suggest that heavy CR species (e.g., iron ions) colliding with dust are able to trigger the explosion. Based on recently calculated local CR spectra, we estimate the expected rate of explosive desorption. The efficiency of the desorption, which in principle affects all solid species independent of their binding energy, is shown to be comparable to other CR desorption mechanisms typically considered in the literature. Also, the theory allows us to estimate the maximum abundances of reactive species that may be stored in the mantles, which provides important constraints on the available astrochemical models.« less

Recognition- and Reactivity-Based Fluorescent Probes for Studying Transition Metal Signaling in Living Systems

PubMed Central

2015-01-01

Conspectus Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed “recognition” and “reactivity”. Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give three recent examples from our laboratory and collaborations in which applications of chemical probes reveal that labile copper contributes to various physiologies. The first example shows that copper is an endogenous regulator of neuronal activity, the second illustrates cellular prioritization of mitochondrial copper homeostasis, and the third identifies the “cuprosome” as a new copper storage compartment in Chlamydomonas reinhardtii green algae. Indeed, recognition- and reactivity-based fluorescent probes have helped to uncover new biological roles for labile transition metals, and the further development of fluorescent probes, including ones with varied Kd values and new reaction triggers and recognition receptors, will continue to reveal exciting and new biological roles for labile transition metals. PMID:26215055

Review of Reactive Power Dispatch Strategies for Loss Minimization in a DFIG-based Wind Farm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Baohua; Hu, Weihao; Hou, Peng

This study reviews and compares the performance of reactive power dispatch strategies for the loss minimization of Doubly Fed Induction Generator (DFIG)-based Wind Farms (WFs). Twelve possible combinations of three WF level reactive power dispatch strategies and four Wind Turbine (WT) level reactive power control strategies are investigated. All of the combined strategies are formulated based on the comprehensive loss models of WFs, including the loss models of DFIGs, converters, filters, transformers, and cables of the collection system. Optimization problems are solved by a Modified Particle Swarm Optimization (MPSO) algorithm. The effectiveness of these strategies is evaluated by simulations onmore » a carefully designed WF under a series of cases with different wind speeds and reactive power requirements of the WF. The wind speed at each WT inside the WF is calculated using the Jensen wake model. The results show that the best reactive power dispatch strategy for loss minimization comes when the WF level strategy and WT level control are coordinated and the losses from each device in the WF are considered in the objective.« less

Review of Reactive Power Dispatch Strategies for Loss Minimization in a DFIG-based Wind Farm

DOE PAGES

Zhang, Baohua; Hu, Weihao; Hou, Peng; ...

2017-06-27

This study reviews and compares the performance of reactive power dispatch strategies for the loss minimization of Doubly Fed Induction Generator (DFIG)-based Wind Farms (WFs). Twelve possible combinations of three WF level reactive power dispatch strategies and four Wind Turbine (WT) level reactive power control strategies are investigated. All of the combined strategies are formulated based on the comprehensive loss models of WFs, including the loss models of DFIGs, converters, filters, transformers, and cables of the collection system. Optimization problems are solved by a Modified Particle Swarm Optimization (MPSO) algorithm. The effectiveness of these strategies is evaluated by simulations onmore » a carefully designed WF under a series of cases with different wind speeds and reactive power requirements of the WF. The wind speed at each WT inside the WF is calculated using the Jensen wake model. The results show that the best reactive power dispatch strategy for loss minimization comes when the WF level strategy and WT level control are coordinated and the losses from each device in the WF are considered in the objective.« less

A cognitive information processing framework for distributed sensor networks

NASA Astrophysics Data System (ADS)

Wang, Feiyi; Qi, Hairong

2004-09-01

In this paper, we present a cognitive agent framework (CAF) based on swarm intelligence and self-organization principles, and demonstrate it through collaborative processing for target classification in sensor networks. The framework involves integrated designs to provide both cognitive behavior at the organization level to conquer complexity and reactive behavior at the individual agent level to retain simplicity. The design tackles various problems in the current information processing systems, including overly complex systems, maintenance difficulties, increasing vulnerability to attack, lack of capability to tolerate faults, and inability to identify and cope with low-frequency patterns. An important and distinguishing point of the presented work from classical AI research is that the acquired intelligence does not pertain to distinct individuals but to groups. It also deviates from multi-agent systems (MAS) due to sheer quantity of extremely simple agents we are able to accommodate, to the degree that some loss of coordination messages and behavior of faulty/compromised agents will not affect the collective decision made by the group.

First-principles quantum dynamical theory for the dissociative chemisorption of H2O on rigid Cu(111)

PubMed Central

Zhang, Zhaojun; Liu, Tianhui; Fu, Bina; Yang, Xueming; Zhang, Dong H.

2016-01-01

Despite significant progress made in the past decades, it remains extremely challenging to investigate the dissociative chemisorption dynamics of molecular species on surfaces at a full-dimensional quantum mechanical level, in particular for polyatomic-surface reactions. Here we report, to the best of our knowledge, the first full-dimensional quantum dynamics study for the dissociative chemisorption of H2O on rigid Cu(111) with all the nine molecular degrees of freedom fully coupled, based on an accurate full-dimensional potential energy surface. The full-dimensional quantum mechanical reactivity provides the dynamics features with the highest accuracy, revealing that the excitations in vibrational modes of H2O are more efficacious than increasing the translational energy in promoting the reaction. The enhancement of the excitation in asymmetric stretch is the largest, but that of symmetric stretch becomes comparable at very low energies. The full-dimensional characterization also allows the investigation of the validity of previous reduced-dimensional and approximate dynamical models. PMID:27283908

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Sandeep, E-mail: sipusukhn@gmail.com; Sharma, Amrish; Mudahar, Isha, E-mail: isha@pbi.ac.in

First principle calculations based on density functional theory were performed to calculate the structural and electronic properties of C{sub 20}-N{sub m}@C{sub n} dimer complexes. The calculated binding energies of the complexes formed are comparable to C{sub 60} dimer which ensures their stability. The bond lengths of these dimer complexes were found to be nearly same as pure complexes C{sub 20}-C{sub n}. Further, nitrogen (N) atoms were encapsulated inside the secondary cage (C{sub n}) of dimer complexes and the number of N atoms depends on diameter of the cage. The HOMO-LUMO gaps of new proposed complexes indicate the increase in gapmore » as compared to pure complexes. Mulliken charge analysis of these complexes has been studied which shows the significant charge transfer from the N atoms to the secondary cage of these complexes. The study propose the formation of the new dimer complexes which are stable and are able to encapsulate atoms which are otherwise reactive in free space.« less

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

DOE PAGES

Kushwaha, Anoop Kumar; Sahoo, Mihir Ranjan; Nanda, Jagjit; ...

2017-07-01

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. Here, we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. In using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li n (n ≤ 8) clusters in both gas phase and solution. We found that Li 3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approachmore » could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li 3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, our study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.« less

Coupling of ab initio density functional theory and molecular dynamics for the multiscale modeling of carbon nanotubes

NASA Astrophysics Data System (ADS)

Ng, T. Y.; Yeak, S. H.; Liew, K. M.

2008-02-01

A multiscale technique is developed that couples empirical molecular dynamics (MD) and ab initio density functional theory (DFT). An overlap handshaking region between the empirical MD and ab initio DFT regions is formulated and the interaction forces between the carbon atoms are calculated based on the second-generation reactive empirical bond order potential, the long-range Lennard-Jones potential as well as the quantum-mechanical DFT derived forces. A density of point algorithm is also developed to track all interatomic distances in the system, and to activate and establish the DFT and handshaking regions. Through parallel computing, this multiscale method is used here to study the dynamic behavior of single-walled carbon nanotubes (SWCNTs) under asymmetrical axial compression. The detection of sideways buckling due to the asymmetrical axial compression is reported and discussed. It is noted from this study on SWCNTs that the MD results may be stiffer compared to those with electron density considerations, i.e. first-principle ab initio methods.

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushwaha, Anoop Kumar; Sahoo, Mihir Ranjan; Nanda, Jagjit

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. Here, we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. In using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li n (n ≤ 8) clusters in both gas phase and solution. We found that Li 3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approachmore » could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li 3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, our study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.« less

Knudsen pump produced via silicon deep RIE, thermal oxidation, and anodic bonding processes for on-chip vacuum pumping

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Inomata, Naoki; Trung, Nguyen Huu; Ono, Takahito

2018-05-01

This work describes the fabrication and evaluation of the Knudsen pump for on-chip vacuum pumping that works based on the principle of a thermal transpiration. Three AFM (atomic force microscope) cantilevers are integrated into small chambers with a size of 5 mm  ×  3 mm  ×  0.4 mm for the pump’s evaluation. Knudsen pump is fabricated using deep RIE (reactive ion etching), wet thermal oxidation and anodic bonding processes. The fabricated device is evaluated by monitoring the quality (Q) factor of the integrated cantilevers. The Q factor of the cantilever is increased from 300 -1150 in cases without and with a temperature difference approximately 25 °C between the top (the hot side at 40 °C) and bottom (the cold side at 15 °C) sides of the fabricated device, respectively. The evacuated chamber pressure of around 10 kPa is estimated from the Q factor of the integrated cantilevers.

Insights into the structure–photoreactivity relationships in well-defined perovskite ferroelectric KNbO 3 nanowires

DOE PAGES

Zhang, Tingting; Lei, Wanying; Liu, Ping; ...

2015-04-23

Structure–function correlations are a central theme in heterogeneous (photo)catalysis. In this study, the geometric and electronic structure of perovskite ferroelectric KNbO 3 nanowires with respective orthorhombic and monoclinic polymorphs have been systematically addressed. By virtue of aberration-corrected scanning transmission electron microscopy, we directly visualize surface photocatalytic active sites, measure local atomic displacements at an accuracy of several picometers, and quantify ferroelectric polarization combined with first-principles calculations. The photoreactivity of the as-prepared KNbO 3 nanowires is assessed toward aqueous rhodamine B degradation under UV light. A synergy between the ferroelectric polarization and electronic structure in photoreactivity enhancement is uncovered, which accountsmore » for the prominent reactivity order: orthorhombic > monoclinic. Additionally, by identifying new photocatalytic products, rhodamine B degradation pathways involving N-deethylation and conjugated structure cleavage are proposed. The findings not only provide new insights into the structure–photoreactivity relationships in perovskite ferroelectric photocatalysts, but also have broad implications in perovskite-based water splitting and photovoltaics, among others.« less

Automated data processing and radioassays.

PubMed

Samols, E; Barrows, G H

1978-04-01

Radioassays include (1) radioimmunoassays, (2) competitive protein-binding assays based on competition for limited antibody or specific binding protein, (3) immunoradiometric assay, based on competition for excess labeled antibody, and (4) radioreceptor assays. Most mathematical models describing the relationship between labeled ligand binding and unlabeled ligand concentration have been based on the law of mass action or the isotope dilution principle. These models provide useful data reduction programs, but are theoretically unfactory because competitive radioassay usually is not based on classical dilution principles, labeled and unlabeled ligand do not have to be identical, antibodies (or receptors) are frequently heterogenous, equilibrium usually is not reached, and there is probably steric and cooperative influence on binding. An alternative, more flexible mathematical model based on the probability or binding collisions being restricted by the surface area of reactive divalent sites on antibody and on univalent antigen has been derived. Application of these models to automated data reduction allows standard curves to be fitted by a mathematical expression, and unknown values are calculated from binding data. The vitrues and pitfalls are presented of point-to-point data reduction, linear transformations, and curvilinear fitting approaches. A third-order polynomial using the square root of concentration closely approximates the mathematical model based on probability, and in our experience this method provides the most acceptable results with all varieties of radioassays. With this curvilinear system, linear point connection should be used between the zero standard and the beginning of significant dose response, and also towards saturation. The importance is stressed of limiting the range of reported automated assay results to that portion of the standard curve that delivers optimal sensitivity. Published methods for automated data reduction of Scatchard plots for radioreceptor assay are limited by calculation of a single mean K value. The quality of the input data is generally the limiting factor in achieving good precision with automated as it is with manual data reduction. The major advantages of computerized curve fitting include: (1) handling large amounts of data rapidly and without computational error; (2) providing useful quality-control data; (3) indicating within-batch variance of the test results; (4) providing ongoing quality-control charts and between assay variance.

Applying Brain-Based Learning Principles to Athletic Training Education

ERIC Educational Resources Information Center

Craig, Debbie I.

2007-01-01

Objective: To present different concepts and techniques related to the application of brain-based learning principles to Athletic Training clinical education. Background: The body of knowledge concerning how our brains physically learn continues to grow. Brain-based learning principles, developed by numerous authors, offer advice on how to…

78 FR 79542 - Self-Regulatory Organizations; Financial Industry Regulatory Authority, Inc.; Order Granting...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-30

... Risk-Based Review Principles Two commenters to the Proposing Release opposed the proposed rules' flexibility permitting members to rely on risk-based or principles- based review standards for specific... Commercial Honor and Principles of Trade), it must include supervision of all of a member's business lines...

Assessing participants' perceptions on group-based principles for action in community-based health enhancing physical activity programmes: The APEF tool.

PubMed

Herens, Marion; Wagemakers, Annemarie

2017-12-01

In community-based health enhancing physical activity (CBHEPA) programmes, group-based principles for action such as active participation, enjoyment, and fostering group processes are widely advocated. However, not much is known about participants' perceptions of these principles as there are no assessment tools available. Therefore, this article describes the development of the APEF (Active Participation, Enjoyment, and Fostering group processes) tool and reports on its implementation in a Dutch CBHEPA programme. Indicators for the principles have been identified from literature research, interviews with professionals, and secondary analysis of three group interviews with 11 practitioners. To address the identified indicators, the APEF tool was developed, pretested, and used in 10 focus groups with 76 participants. The APEF tool consists of eight statements about group-based principles for action, on which CBHEPA participants vote, followed by in-depth discussion. The voting procedure engages participants. Spider diagrams visualise participants' perceptions of group-based principles. The APEF tool addresses the challenge of relating group level outcomes to individual outcomes such as physical activity behaviour. The tool facilitates as well as evaluates group-based principles for action, it stimulates dialogue and is culturally sensitive, but it needs strong facilitating skills to manage group dynamics. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Progress in performance enhancement methods for capacitive silicon resonators

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Ono, Takahito

2017-11-01

In this paper, we review the progress in recent studies on the performance enhancement methods for capacitive silicon resonators. We provide information on various fabrication technologies and design considerations that can be employed to improve the performance of capacitive silicon resonators, including low motional resistance, small insertion loss, and high quality factor (Q). This paper contains an overview of device structures and working principles, fabrication technologies consisting of hermetic packaging, deep reactive-ion etching and neutral beam etching, and design considerations including mechanically coupled, movable electrode structures and piezoresistive heat engines.

[Pathogenetic characteristics of trigger mechanisms of preterm birth].

PubMed

Holota, V Ia; Beniuk, V O; Chernenko, V Iu

2000-01-01

A study was made into the immune factors capability to induce labour in physiologic delivery and in threat of preterm birth. The immune response reactivity was proved to be the case immediately before the physiological labour and in premature delivery. The studies made showed that a rise in the level of lymphocytes and in the subpopulations ratios is a matter of principle in the diagnosis and prognosis of the contractile activity of the uterus. Preclinical diagnosis of pregnancy suspension permit performing a rational drug correction to secure a positive effect on indices for perinatal pathology.

[The history of hepatitis B virus-related determination tests and inspection and the measurements of problems in Japan].

PubMed

Shibata, Hiroshi

2013-09-01

Since Hepatitis B virus was detected as the cause of hepatitis, many high-sensitive measurement methods have been developed. In the development history, there are many problems in accuracy, sensitivity and health insurance regulations among different types of kits with different measurement principles. Advanced medical treatments cause problems of gene mutation or reactivation of HBV, leading to the necessity for high sensitive and sophisticated determination. The history of clinical analysis for the detection of HBV was reviewed from the viewpoint of our experiences.

Carbon reactivation kinetics in the base of heterojunction GaInP-GaAs bipolar transistors

NASA Astrophysics Data System (ADS)

Mimila-Arroyo, J.; Bland, S. W.; Chevallier, J.

2002-05-01

The reactivation kinetics of carbon acceptors in the base region of GaInP/GaAs heterojunction bipolar transistors was studied. The reactivation was achieved by ex situ thermal annealing, through a multistage annealing experiment where the carrier concentration was monitored at each stage. Results indicate that carbon reactivation follows a first-order kinetics process in which the activation energy appears to be the sum of the energy needed to debond the hydrogen from the carbon-hydrogen complex, and the energy necessary to overcome the electrostatic junction barrier. The reactivation constant is thermally activated with an activation energy of 2.83 eV and an attempt frequency of 1.2×1013 s-1.

Vitellogenins Are New High Molecular Weight Components and Allergens (Api m 12 and Ves v 6) of Apis mellifera and Vespula vulgaris Venom

PubMed Central

Blank, Simon; Seismann, Henning; McIntyre, Mareike; Ollert, Markus; Wolf, Sara; Bantleon, Frank I.; Spillner, Edzard

2013-01-01

Background/Objectives Anaphylaxis due to hymenoptera stings is one of the most severe clinical outcomes of IgE-mediated hypersensitivity reactions. Although allergic reactions to hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, venom immunotherapy is still hampered by severe systemic side effects and incomplete protection. The identification and detailed characterization of all allergens of hymenoptera venoms might result in an improvement in this field and promote the detailed understanding of the allergological mechanism. Our aim was the identification and detailed immunochemical and allergological characterization of the low abundant IgE-reactive 200 kDa proteins of Apis mellifera and Vespula vulgaris venom. Methods/Principal Findings Tandem mass spectrometry-based sequencing of a 200 kDa venom protein yielded peptides that could be assigned to honeybee vitellogenin. The coding regions of the honeybee protein as well as of the homologue from yellow jacket venom were cloned from venom gland cDNA. The newly identified 200 kDa proteins share a sequence identity on protein level of 40% and belong to the family of vitellogenins, present in all oviparous animals, and are the first vitellogenins identified as components of venom. Both vitellogenins could be recombinantly produced as soluble proteins in insect cells and assessed for their specific IgE reactivity. The particular vitellogenins were recognized by approximately 40% of sera of venom-allergic patients even in the absence of cross-reactive carbohydrate determinants. Conclusion With the vitellogenins of Apis mellifera and Vespula vulgaris venom a new homologous pair of venom allergens was identified and becomes available for future applications. Due to their allergenic properties the honeybee and the yellow jacket venom vitellogenin were designated as allergens Api m 12 and Ves v 6, respectively. PMID:23626765

Feasibility of Using Virtual Reality to Assess Nicotine Cue Reactivity during Treatment

ERIC Educational Resources Information Center

Kaganoff, Eili; Bordnick, Patrick S.; Carter, Brian Lee

2012-01-01

Cue reactivity assessments have been widely used to assess craving and attention to cues among cigarette smokers. Cue reactivity has the potential to offer insights into treatment decisions; however, the use of cue reactivity in treatment studies has been limited. This study assessed the feasibility of using a virtual reality-based cue reactivity…

Development of Metal Cluster-Based Energetic Materials at NSWC-IHD

DTIC Science & Technology

2011-01-01

reactivity of NixAly + clusters with nitromethane was investigated using a gas-phase molecular beam system. Results indicate that nitromethane is highly...clusters make up the subunit of a molecular metal-based energetic material. The reactivity of NixAly+ clusters with nitromethane was investigated using...a gas-phase molecular beam system. Results indicate that nitromethane is highly reactive toward the NixAly+ clusters and suggests it would not make

Introducing new reactivity descriptors: "Bond reactivity indices." Comparison of the new definitions and atomic reactivity indices.

PubMed

Sánchez-Márquez, Jesús

2016-11-21

A new methodology to obtain reactivity indices has been defined. This is based on reactivity functions such as the Fukui function or the dual descriptor and makes it possible to project the information of reactivity functions over molecular orbitals instead of the atoms of the molecule (atomic reactivity indices). The methodology focuses on the molecule's natural bond orbitals (bond reactivity indices) because these orbitals (with physical meaning) have the advantage of being very localized, allowing the reaction site of an electrophile or nucleophile to be determined within a very precise molecular region. This methodology gives a reactivity index for every Natural Bond Orbital (NBO), and we have verified that they have equivalent information to the reactivity functions. A representative set of molecules has been used to test the new definitions. Also, the bond reactivity index has been related with the atomic reactivity one, and complementary information has been obtained from the comparison. Finally, a new atomic reactivity index has been defined and compared with previous definitions.

Mindfulness-Based Cognitive Therapy Improves Emotional Reactivity to Social Stress: Results from A Randomized Controlled Trial

PubMed Central

Britton, Willoughby B.; Shahar, Ben; Szepsenwol, Ohad; Jacobs, W. Jake

2012-01-01

Objectives The high likelihood of recurrences in depression is linked to progressive increase in emotional reactivity to stress (stress sensitization). Mindfulness-based therapies teach mindfulness skills designed to decrease emotional reactivity in the face of negative-affect producing stressors. The primary aim of the current study was to assess whether Mindfulness-Based Cognitive Therapy (MBCT) is efficacious in reducing emotional reactivity to social evaluative threat in a clinical sample with recurrent depression. A secondary aim was to assess whether improvement in emotional reactivity mediates improvements in depressive symptoms. Methods Fifty-two individuals with partially-remitted depression were randomized into an 8-week MBCT course or a waitlist control condition. All participants underwent the Trier Social Stress Test (TSST) before and after the 8-week trial period. Emotional reactivity to stress was assessed with the Spielberger State Anxiety Inventory at several time points before, during and after the stressor. Results MBCT was associated with decreased emotional reactivity to social stress, specifically during the recovery (post-stressor) phase of the TSST. Waitlist controls showed an increase in anticipatory (pre-stressor) anxiety, which was absent in the MBCT group. Improvements in emotional reactivity partially mediated improvements in depressive symptoms. Limitations Limitations include small sample size, lack of objective or treatment adherence measures, and non-generalizability to more severely depressed populations. Conclusions Given that emotional reactivity to stress is an important psychopathological process underlying the chronic and recurrent nature of depression, these findings suggest that mindfulness skills are important in adaptive emotion regulation when coping with stress. PMID:22440072

Principle-Based Inferences in Young Children's Categorization: Revisiting the Impact of Function on the Naming of Artifacts.

ERIC Educational Resources Information Center

Nelson, Deborah G. Kemler

1995-01-01

Three studies investigated the influence of principle-based inferences and unprincipled similarity relations on new category learning by three- to six-year-old children. Results indicated that categorization into newly learned categories may activate self-initiated, principle-based reasoning in young children, suggesting that spontaneous…

Sustaining Knowledge Building as a Principle-Based Innovation at an Elementary School

ERIC Educational Resources Information Center

Zhang, Jianwei; Hong, Huang-Yao; Scardamalia, Marlene; Teo, Chew Lee; Morley, Elizabeth A.

2011-01-01

This study explores Knowledge Building as a principle-based innovation at an elementary school and makes a case for a principle- versus procedure-based approach to educational innovation, supported by new knowledge media. Thirty-nine Knowledge Building initiatives, each focused on a curriculum theme and facilitated by nine teachers over eight…

75 FR 8239 - School Food Safety Program Based on Hazard Analysis and Critical Control Point Principles (HACCP...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-24

... 0584-AD65 School Food Safety Program Based on Hazard Analysis and Critical Control Point Principles... Safety Program Based on Hazard Analysis and Critical Control Point Principles (HACCP) was published on... of Management and Budget (OMB) cleared the associated information collection requirements (ICR) on...

Theoretical and experimental insights into the origin of the catalytic activity of subnanometric gold clusters: attempts to predict reactivity with clusters and nanoparticles of gold.

PubMed

Boronat, Mercedes; Leyva-Pérez, Antonio; Corma, Avelino

2014-03-18

Particle size is one of the key parameters determining the unexpected catalytic activity of gold, with reactivity improving as the particle gets smaller. While this is valid in the 1-5 nm range, chemists are now investigating the influence of particle size in the subnanometer regime. This is due to recent advances in both characterization techniques and synthetic routes capable of stabilizing these size-controlled gold clusters. Researchers reported in early studies that small clusters or aggregates of a few atoms can be extremely active in some reactions, while 1-2 nm nanoparticles are catalytically more efficient for other reactions. Furthermore, the possibility that small gold clusters generated in situ from gold salts or complexes could be the real active species in homogeneous gold-catalyzed organic reactions should be considered. In this Account, we address two questions. First, what is the origin of the enhanced reactivity of gold clusters on the subnanometer scale? And second, how can we predict the reactions where small clusters should work better than larger nanoparticles? Both geometric factors and electronic or quantum size effects become important in the subnanometer regime. Geometric reasons play a key role in hydrogenation reactions, where only accessible low coordinated neutral Au atoms are needed to dissociate H2. The quantum size effects of gold clusters are important as well, as clusters formed by only a few atoms have discrete molecule-like electronic states and their chemical reactivity is related to interactions between the cluster's frontier molecular orbitals and those of the reactant molecules. From first principles calculations, we predict an enhanced reactivity of small planar clusters for reactions involving activation of CC multiple bonds in alkenes and alkynes through Lewis acid-base interactions, and a better catalytic performance of 3D gold nanoparticles in redox reactions involving bond dissociation by oxidative addition and new bond formation by reductive elimination. In oxidation reactions with molecular O2, initial dissociation of O2 into basic oxygen atoms would be more effectively catalyzed by gold nanoparticles of ∼1 nm diameter. In contrast, small planar clusters should be more active for reactions following a radical pathway involving peroxo or hydroperoxo intermediates. We have experimentally confirmed these predictions for a series of Lewis acid and oxidation reactions catalyzed by gold clusters and nanoparticles either in solution or supported on solid carriers.

Sensitivity-Based VOC Reactivity Calculation

EPA Science Inventory

Volatile Organic Compound (VOC) reactivity scales are used to compare the ozone-forming potentials of various compounds. The comparison allows for substitution of compounds to lessen formation of ozone from paints, solvents, and other products. Current reactivity scales for VOC c...

FRET-based genetically-encoded sensors for quantitative monitoring of metabolites.

PubMed

Mohsin, Mohd; Ahmad, Altaf; Iqbal, Muhammad

2015-10-01

Neighboring cells in the same tissue can exist in different states of dynamic activities. After genomics, proteomics and metabolomics, fluxomics is now equally important for generating accurate quantitative information on the cellular and sub-cellular dynamics of ions and metabolite, which is critical for functional understanding of organisms. Various spectrometry techniques are used for monitoring ions and metabolites, although their temporal and spatial resolutions are limited. Discovery of the fluorescent proteins and their variants has revolutionized cell biology. Therefore, novel tools and methods targeting sub-cellular compartments need to be deployed in specific cells and targeted to sub-cellular compartments in order to quantify the target-molecule dynamics directly. We require tools that can measure cellular activities and protein dynamics with sub-cellular resolution. Biosensors based on fluorescence resonance energy transfer (FRET) are genetically encoded and hence can specifically target sub-cellular organelles by fusion to proteins or targetted sequences. Since last decade, FRET-based genetically encoded sensors for molecules involved in energy production, reactive oxygen species and secondary messengers have helped to unravel key aspects of cellular physiology. This review, describing the design and principles of sensors, presents a database of sensors for different analytes/processes, and illustrate examples of application in quantitative live cell imaging.

Application of a data assimilation method via an ensemble Kalman filter to reactive urea hydrolysis transport modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juxiu Tong; Bill X. Hu; Hai Huang

2014-03-01

With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations,more » we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study.« less

Implementing Set Based Design into Department of Defense Acquisition

DTIC Science & Technology

2016-12-01

challenges for the DOD. This report identifies the original SBD principles and characteristics based on Toyota Motor Corporation’s Set Based Concurrent...Engineering Model. Additionally, the team reviewed DOD case studies that implemented SBD. The SBD principles , along with the common themes from the...perennial challenges for the DOD. This report identifies the original SBD principles and characteristics based on Toyota Motor Corporation’s Set

Slit shaped microwave induced atmospheric pressure plasma based on a parallel plate transmission line resonator

NASA Astrophysics Data System (ADS)

Kang, S. K.; Seo, Y. S.; Lee, H. Wk; Aman-ur-Rehman; Kim, G. C.; Lee, J. K.

2011-11-01

A new type of microwave-excited atmospheric pressure plasma source, based on the principle of parallel plate transmission line resonator, is developed for the treatment of large areas in biomedical applications such as skin treatment and wound healing. A stable plasma of 20 mm width is sustained by a small microwave power source operated at a frequency of 700 MHz and a gas flow rate of 0.9 slm. Plasma impedance and plasma density of this plasma source are estimated by fitting the calculated reflection coefficient to the measured one. The estimated plasma impedance shows a decreasing trend while estimated plasma density shows an increasing trend with the increase in the input power. Plasma uniformity is confirmed by temperature and optical emission distribution measurements. Plasma temperature is sustained at less than 40 °C and abundant amounts of reactive species, which are important agents for bacteria inactivation, are detected over the entire plasma region. Large area treatment ability of this newly developed device is verified through bacteria inactivation experiment using E. coli. Sterilization experiment shows a large bacterial killing mark of 25 mm for a plasma treatment time of 10 s.

DNA-binding studies of a tetraalkyl-substituted porphyrin and the mutually adaptive distortion principle.

PubMed

Ghimire, Srijana; Fanwick, Phillip E; McMillin, David R

2014-10-20

This investigation explores DNA-binding interactions of various forms of an alkyl-substituted cationic porphyrin, H2TC3 (5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)]porphyrin). The motivating idea is that incorporating alkyl rather than aryl substituents in the meso positions will enhance the prospects for intercalative as well as external binding to DNA hosts. The ligands may also be applicable for photodynamic and/or anticancer therapy. Methods employed include absorbance, circular dichroism, and emission spectroscopies, as well as viscometry and X-ray crystallography. By comparison with the classical H2T4 system, H2TC3 exhibits a higher molar extinction coefficient but is more prone to self-association. Findings of note include that the copper(II)-containing form Cu(TC3) is adept at internalizing into single-stranded as well as B-form DNA, regardless of the base composition. Surprisingly, however, external binding of H2TC3 occurs within domains that are rich in adenine-thymine base pairs. The difference in the deformability of H2TC3 versus Cu(TC3) probably accounts for the reactivity difference. Finally, Zn(TC3) binds externally, as the metal center remains five-coordinate.

Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose.

PubMed

Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc; Singaram, Bakthan

2017-11-22

To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen-HPTS (4,4'-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH 4 ) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4-25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H 2 O 2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4'-o-BBV-HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc.

Roles of the Lewis acid and base in the chemical reduction of CO2 catalyzed by frustrated Lewis pairs.

PubMed

Lim, Chern-Hooi; Holder, Aaron M; Hynes, James T; Musgrave, Charles B

2013-09-03

We employ quantum chemical calculations to discover how frustrated Lewis pairs (FLP) catalyze the reduction of CO2 by ammonia borane (AB); specifically, we examine how the Lewis acid (LA) and Lewis base (LB) of an FLP activate CO2 for reduction. We find that the LA (trichloroaluminum, AlCl3) alone catalyzes hydride transfer (HT) to CO2 while the LB (trimesitylenephosphine, PMes3) actually hinders HT; inclusion of the LB increases the HT barrier by ∼8 kcal/mol relative to the reaction catalyzed by LAs only. The LB hinders HT by donating its lone pair to the LUMO of CO2, increasing the electron density on the C atom and thus lowering its hydride affinity. Although the LB hinders HT, it nonetheless plays a crucial role by stabilizing the active FLP·CO2 complex relative to the LA dimer, free CO2, and free LB. This greatly increases the concentration of the reactive complex in the form FLP·CO2 and thus increases the rate of reaction. We expect that the principles we describe will aid in understanding other catalytic CO2 reductions.

Three-dimensional WS2 nanosheet networks for H2O2 produced for cell signaling

NASA Astrophysics Data System (ADS)

Tang, Jing; Quan, Yingzhou; Zhang, Yueyu; Jiang, Min; Al-Enizi, Abdullah M.; Kong, Biao; An, Tiance; Wang, Wenshuo; Xia, Limin; Gong, Xingao; Zheng, Gengfeng

2016-03-01

Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems.Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems. Electronic supplementary information (ESI) available: Additional figures. See DOI: 10.1039/c5nr09236a

Reactivation of model cholinesterases by oximes and intermediate phosphyloximes: A computational study

PubMed Central

Vyas, Shubham; Hadad, Christopher M.

2008-01-01

Phosphyloximes (POX) are generated upon the reactivation of organophosphorus (OP) inhibited cholinesterases (ChEs) by pyridinium oximes. These POXs are known to be potent inhibitors of the ChEs following reactivation. However, they can also decompose to give an OP derivative and a cyano derivative of the oxime when a base abstracts the benzylic proton. Using density functional theory, thermodynamic properties were calculated for the reactivation and decomposition pathways of three different oximes (2-PAM, 3-PAM and 4-PAM) with six different OPs (cyclosarin, paraoxon, sarin, tabun, VR and VX). For reactivation purposes, 2-PAM is predicted to be more efficient than 3- and 4-PAM. Based on atomic charges and relative energies, 2-POXs were found to be more inclined towards the decomposition process. PMID:18582852

Kinetics of biological decolorisation of anthraquinone based Reactive Blue 19 using an isolated strain of Enterobacter sp.F NCIM 5545.

PubMed

Holkar, Chandrakant R; Pandit, Aniruddha B; Pinjari, Dipak V

2014-12-01

In the present study, an attempt was made to evaluate the bacterial decolorisation of Reactive Blue 19 by an Enterobacter sp.F which was isolated from a mixed culture from anaerobic digester for biogas production. Phenotypic characterization and phylogenetic analysis based on DNA sequencing comparisons indicate that Enterobacter sp.F was 99.7% similar to Enterobacter cloacae ATCC13047. The kinetics of Reactive Blue 19 dye decolorisation by bacterium had been estimated. Effects of substrate concentration, oxygen, temperature, pH, glucose and glucose to microbe weight ratio on the rate of decolorisation were investigated to understand key factor that determines the performance of dye decolorisation. The maximum decolorisation efficiency of Reactive Blue 19 was 90% over period of 24 h for optimized parameter. To the best of our knowledge, this research study is the report where Enterobacter sp.F has been reported with about 90% decolorizing ability against anthraquinone based Reactive Blue 19 dye. Copyright © 2014 Elsevier Ltd. All rights reserved.

Micrometer sized immobilization of protein molecules onto quartz, silicium and gold.

NASA Astrophysics Data System (ADS)

Petersen, Steffen B.; Neves-Petersen, Maria Teresa; Klitgaard, Søren; Duroux, Meg Crookshanks

2006-02-01

We demonstrate that ultraviolet light can be used to make sterically oriented covalent immobilization of a large variety of protein molecules onto either gold or thiolated quartz or silicium. The reaction mechanism behind the reported new technology involves light induced breakage of disulphide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol reactive surfaces. The protein molecules in general retain their function. The size of the immobilization spot is determined by the dimension of the UV beam. In principle, the spot size may be as small as 1 micrometer or less. We have developed the necessary technology for preparing large protein arrays of enzymes and fragments of monoclonal antibodies. Dedicated Image Processing Software has been developed for making quality assessment of the protein arrays. A multitude of important application areas such as drug carriers and drug delivery, bioelectronics, carbon nanotubes, nanoparticles as well as protein glue are discussed.

Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

NASA Astrophysics Data System (ADS)

Gao, Chao; Lu, Yunhao; Dong, Peng; Yi, Jun; Ma, Xiangyang; Yang, Deren

2014-01-01

The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300-500 °C leads to further B deactivation, while that at 600-800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B2I complexes results in further B deactivation in the following CFA at 300-500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600-800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.

A Novel Tumor-Activated Prodrug Strategy Targeting Ferrous Iron Is Effective in Multiple Preclinical Cancer Models

PubMed Central

2016-01-01

Here we describe a new approach for tumor targeting in which augmented concentrations of Fe(II) in cancer cells and/or the tumor microenvironment triggers drug release from an Fe(II)-reactive prodrug conjugate. The 1,2,4-trioxolane scaffold developed to enable this approach can in principle be applied to a broad range of cancer therapeutics and is illustrated here with Fe(II)-targeted forms of a microtubule toxin and a duocarmycin-class DNA-alkylating agent. We show that the intrinsic reactivity/toxicity of the duocarmycin analog is masked in the conjugated form and this greatly reduced toxicity in mice. This in turn permitted elevated dosing levels, leading to higher systemic exposure and a significantly improved response in tumor xenograft models. Overall our results suggest that Fe(II)-dependent drug delivery via trioxolane conjugates could have significant utility in expanding the therapeutic index of a range of clinical and preclinical stage cancer chemotherapeutics. PMID:27936709

Carbon nitride supported Fe2 cluster catalysts with superior performance for alkene epoxidation.

PubMed

Tian, Shubo; Fu, Qiang; Chen, Wenxing; Feng, Quanchen; Chen, Zheng; Zhang, Jian; Cheong, Weng-Chon; Yu, Rong; Gu, Lin; Dong, Juncai; Luo, Jun; Chen, Chen; Peng, Qing; Draxl, Claudia; Wang, Dingsheng; Li, Yadong

2018-06-15

Sub-nano metal clusters often exhibit unique and unexpected properties, which make them particularly attractive as catalysts. Herein, we report a "precursor-preselected" wet-chemistry strategy to synthesize highly dispersed Fe 2 clusters that are supported on mesoporous carbon nitride (mpg-C 3 N 4 ). The obtained Fe 2 /mpg-C 3 N 4 sample exhibits superior catalytic performance for the epoxidation of trans-stilbene to trans-stilbene oxide, showing outstanding selectivity of 93% at high conversion of 91%. Molecular oxygen is the only oxidant and no aldehyde is used as co-reagent. Under the same condition, by contrast, iron porphyrin, single-atom Fe, and small Fe nanoparticles (ca. 3 nm) are nearly reactively inert. First-principles calculations reveal that the unique reactivity of the Fe 2 clusters originates from the formation of active oxygen species. The general applicability of the synthesis approach is further demonstrated by producing other diatomic clusters like Pd 2 and Ir 2 , which lays the foundation for discovering diatomic cluster catalysts.

Social information processing, subtypes of violence, and a progressive construction of culpability and punishment in juvenile justice.

PubMed

Fontaine, Reid Griffith

2008-01-01

Consistent with core principles of liberal theories of punishment (including humane treatment of offenders, respecting offender rights, parsimony, penal proportionality, and rehabilitation), progressive frameworks have sought to expand doctrines of mitigation and excuse in order to reduce culpability and punishment. With respect to juvenile justice, scholars have proposed that doctrinal mitigation be broadened, and that adolescents, due to aspects of developmental immaturity (such as decision-making capacity), be punished less severely than adults who commit the same crimes. One model of adolescent antisocial behavior that may be useful to a progressive theory of punishment in juvenile justice distinguishes between instrumental violence, by which the actor behaves thoughtfully and calmly to achieve personal gain, and reactive violence, which is characterized as impulsive, emotional retaliation toward a perceived threat or injustice. In particular, social cognitive differences between instrumental and reactive violence have implications for responsibility, length and structure of incarceration, rehabilitation, and other issues that are central to a progressive theory of juvenile culpability and punishment.

Magnetic switching in Crx (x = 2-8) and its oxide cluster series

NASA Astrophysics Data System (ADS)

Shah, Esha V.; Roy, Debesh R.

2018-04-01

First principle studies on the magnetic ground state structure, noncollinearity, binding energy and various electronic properties of a series of Crx (x = 2-8) clusters are performed. In order to investigate the effect of ionization and oxidation on the clusters, the anionic (Crx-) and oxidized (CrxO2) analogues of those clusters are also studied in detail. To calculate adiabatic electron affinity of CrxO2 clusters, additionally CrxO2- analogues are also included in the present work. An interesting even (non-magnetic) - odd (magnetic) feature in the considered cluster series has been noticed. The similar behavior is also reflected from their electronic properties as even (less reactive) - odd (more reactive). The most of the neutral and ionized chromium clusters, viz., Crx and Crx- are found to be noncollinear in their ground states, whereas oxidation stabilized those clusters into the collinear spin alignments. The bond distances of Cr clusters are found to be close with available experimental studies.

Monetary incentive moderates the effect of implicit fear on effort-related cardiovascular response.

PubMed

Chatelain, Mathieu; Gendolla, Guido H E

2016-05-01

Integrating the implicit-affect-primes-effort model (Gendolla, 2012, 2015) with the principles of motivational intensity theory (Brehm & Self, 1989) we investigated if the effort mobilization deficit observed in people exposed to fear primes (vs. anger primes) in a difficult short-term memory task could be compensated by high monetary incentive. Effort was operationalized as cardiac response. We expected that fear primes should lead to the strongest cardiac pre-ejection period (PEP) reactivity when incentive was high (high subjective demand and high justified effort) and to the weakest response when incentive was low (high subjective demand but only low justified effort). PEP reactivity in the anger-prime conditions should fall in between (high but feasible demand). We obtained the predicted pattern on responses of PEP and systolic blood pressure. The present findings show for the first time that the effort mobilization deficit of participants exposed to fear primes in a difficult cognitive task could be compensated by a high incentive. Copyright © 2016 Elsevier B.V. All rights reserved.

Blood pressure reactivity to psychological stress is associated with clinical outcomes in patients with heart failure.

PubMed

Sherwood, Andrew; Hill, LaBarron K; Blumenthal, James A; Adams, Kirkwood F; Paine, Nicola J; Koch, Gary G; O'Connor, Christopher M; Johnson, Kristy S; Hinderliter, Alan L

2017-09-01

Cardiovascular (CV) reactivity to psychological stress has been implicated in the development and exacerbation of cardiovascular disease (CVD). Although high CV reactivity traditionally is thought to convey greater risk of CVD, the relationship between reactivity and clinical outcomes is inconsistent and may depend on the patient population under investigation. The present study examined CV reactivity in patients with heart failure (HF) and its potential association with long-term clinical outcomes. One hundred ninety-nine outpatients diagnosed with HF, with ejection fraction ≤40%, underwent an evaluation of blood pressure (BP) and heart rate reactivity to a laboratory-based simulated public-speaking stressor. Cox proportional hazards regression models were used to examine the prospective association between BP and heart rate reactivity on a combined end point of death or CV hospitalization over a 5-year median follow-up period. Both systolic blood pressure (SBP) and diastolic blood pressure (DBP) reactivity, quantified as continuous variables, were inversely related to risk of death or CV hospitalization (Ps < .01) after controlling for established risk factors, including HF disease severity and etiology. In similar models, heart rate reactivity was unrelated to outcome (P = .12). In models with tertiles of reactivity, high SBP reactivity, compared with intermediate SBP reactivity, was associated with lower risk (hazard ratio [HR] = .498, 95% CI .335-.742, P =.001), whereas low SBP reactivity did not differ from intermediate reactivity. For DBP, high reactivity was marginally associated with lower risk compared with intermediate DBP reactivity (HR = .767, 95% CI .515-1.14, P =.193), whereas low DBP reactivity was associated with greater risk (HR = 1.49, 95% CI 1.027-2.155, P =.0359). No relationship of heart rate reactivity to outcome was identified. For HF patients with reduced ejection fraction, a robust increase in BP evoked by a laboratory-based psychological challenge was associated with lower risk for adverse CVD events and may be a novel and unique marker of left ventricular systolic reserve that is accompanied by a more favorable long-term prognosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.

PubMed

Domingo, Luis R; Ríos-Gutiérrez, Mar; Pérez, Patricia

2016-06-09

Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic P k + and nucleophilic P k - Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.

Adolescents' Emotional Reactivity across Relationship Contexts

ERIC Educational Resources Information Center

Cook, Emily C.; Buehler, Cheryl; Blair, Bethany L.

2013-01-01

Adolescents' emotional reactivity in family, close friendships, and romantic relationships was examined in a community-based sample of 416 two-parent families. Six waves of annual data were analyzed using structural equation modeling. Emotional reactivity to interparental conflict during early adolescence was associated prospectively with…

The mediating effect of mindful non-reactivity in exposure-based cognitive behavior therapy for severe health anxiety.

PubMed

Hedman, Erik; Hesser, Hugo; Andersson, Erik; Axelsson, Erland; Ljótsson, Brjánn

2017-08-01

Exposure-based cognitive behavior therapy (CBT) has been shown to be effective in the treatment of severe health anxiety, but little is known about mediators of treatment effect. The aim of the present study was to investigate mindful non-reactivity as a putative mediator of health anxiety outcome using data from a large scale randomized controlled trial. We assessed mindful non-reactivity using the Five Facets Mindfulness Questionnaire-Non-Reactivity scale (FFMQ-NR) and health anxiety with the Short Health Anxiety Inventory (SHAI). Participants with severe health anxiety (N=158) were randomized to internet-delivered exposure-based CBT or behavioral stress management (BSM) and throughout the treatment, both the mediator and outcome were measured weekly. As previously reported, exposure-based CBT was more effective than BSM in reducing health anxiety. In the present study, latent process growth modeling showed that treatment condition had a significant effect on the FFMQ-NR growth trajectory (α-path), estimate=0.18, 95% CI [0.04, 0.32], p=.015, indicating a larger increase in mindful non-reactivity among participants receiving exposure-based CBT compared to the BSM group. The FFMQ-NR growth trajectory was significantly correlated with the SHAI trajectory (β-path estimate=-1.82, 95% CI [-2.15, -1.48], p<.001. Test of the indirect effect, i.e. the estimated mediation effect (αβ) revealed a significant cross product of -0.32, which was statistically significant different from zero based on the asymmetric confidence interval method, 95% CI [-0.59, -0.06]. We conclude that increasing mindful non-reactivity may be of importance for achieving successful treatment outcomes in exposure-based CBT for severe health anxiety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Principle-based concept analysis: Caring in nursing education

PubMed Central

Salehian, Maryam; Heydari, Abbas; Aghebati, Nahid; Moonaghi, Hossein Karimi; Mazloom, Seyed Reza

2016-01-01

Introduction The aim of this principle-based concept analysis was to analyze caring in nursing education and to explain the current state of the science based on epistemologic, pragmatic, linguistic, and logical philosophical principles. Methods A principle-based concept analysis method was used to analyze the nursing literature. The dataset included 46 English language studies, published from 2005 to 2014, and they were retrieved through PROQUEST, MEDLINE, CINAHL, ERIC, SCOPUS, and SID scientific databases. The key dimensions of the data were collected using a validated data-extraction sheet. The four principles of assessing pragmatic utility were used to analyze the data. The data were managed by using MAXQDA 10 software. Results The scientific literature that deals with caring in nursing education relies on implied meaning. Caring in nursing education refers to student-teacher interactions that are formed on the basis of human values and focused on the unique needs of the students (epistemological principle). The result of student-teacher interactions is the development of both the students and the teachers. Numerous applications of the concept of caring in nursing education are available in the literature (pragmatic principle). There is consistency in the meaning of the concept, as a central value of the faculty-student interaction (linguistic principle). Compared with other related concepts, such as “caring pedagogy,” “value-based education,” and “teaching excellence,” caring in nursing education does not have exact and clear conceptual boundaries (logic principle). Conclusion Caring in nursing education was identified as an approach to teaching and learning, and it is formed based on teacher-student interactions and sustainable human values. A greater understanding of the conceptual basis of caring in nursing education will improve the caring behaviors of teachers, create teaching-learning environments, and help experts in curriculum development. PMID:27123225

Principle-based concept analysis: Caring in nursing education.

PubMed

Salehian, Maryam; Heydari, Abbas; Aghebati, Nahid; Karimi Moonaghi, Hossein; Mazloom, Seyed Reza

2016-03-01

The aim of this principle-based concept analysis was to analyze caring in nursing education and to explain the current state of the science based on epistemologic, pragmatic, linguistic, and logical philosophical principles. A principle-based concept analysis method was used to analyze the nursing literature. The dataset included 46 English language studies, published from 2005 to 2014, and they were retrieved through PROQUEST, MEDLINE, CINAHL, ERIC, SCOPUS, and SID scientific databases. The key dimensions of the data were collected using a validated data-extraction sheet. The four principles of assessing pragmatic utility were used to analyze the data. The data were managed by using MAXQDA 10 software. The scientific literature that deals with caring in nursing education relies on implied meaning. Caring in nursing education refers to student-teacher interactions that are formed on the basis of human values and focused on the unique needs of the students (epistemological principle). The result of student-teacher interactions is the development of both the students and the teachers. Numerous applications of the concept of caring in nursing education are available in the literature (pragmatic principle). There is consistency in the meaning of the concept, as a central value of the faculty-student interaction (linguistic principle). Compared with other related concepts, such as "caring pedagogy," "value-based education," and "teaching excellence," caring in nursing education does not have exact and clear conceptual boundaries (logic principle). Caring in nursing education was identified as an approach to teaching and learning, and it is formed based on teacher-student interactions and sustainable human values. A greater understanding of the conceptual basis of caring in nursing education will improve the caring behaviors of teachers, create teaching-learning environments, and help experts in curriculum development.

A Study in Sexual Health Applying the Principles of Community-Based Participatory Research

PubMed Central

Reece, Michael; Dodge, Brian

2012-01-01

The principles of community-based participatory research were applied to an exploratory sexual health study that examined “cruising for sex” among men on a college campus. In the context of a study seeking a broad interpretation of the health implications of cruising, and when faced with methodological challenges, the researchers found these principles to provide invaluable guidance. A review of the research process is offered and the manner in which the principles of community-based participatory research were operationalized for this study is described. PMID:15129042

Identification of a pharmacological target for genioglossus reactivation throughout sleep.

PubMed

Grace, Kevin P; Hughes, Stuart W; Horner, Richard L

2014-01-01

Obstructive sleep apnea (OSA) is a significant public health problem caused by repeated episodes of upper airway closure that occur only during sleep. Attempts to treat OSA pharmacologically have been unsuccessful because there has not been identification of a target operating at cranial motor nuclei, blockade of which can reactivate pharyngeal muscle activity throughout sleep. Increasing potassium conductance is a common mechanism by which state-dependent neuromodulators reduce motoneuron excitability. Therefore, we aimed to determine if potassium channel blockade is an effective strategy to reactivate the pharyngeal musculature throughout sleep. In rats chronically instrumented for recording sleep-wake states and respiratory motor activities, we locally microperfused pharmacological agents into the hypoglossal motor pool to modulate potassium channels of three major classes: inwardly rectifying, two-pore domain, and voltage-gated. Microperfusion of the inwardly rectifying potassium channel blocker, barium, as well as the voltage-gated potassium channel blockers, tetraethylammonium and 4-aminopyridine, increased tonic and respiratory-related genioglossus activities throughout nonrapid eye movement (non-REM) and rapid eye movement (REM) sleep to 133-300% of levels present during baseline wakefulness. In contrast, microperfusion of methanandamide (TWIK-related acid-sensitive potassium [TASK] channel blocker/cannabinoid receptor agonist) activated genioglossus in wakefulness but not in sleep. These findings establish proof-of-principle that targeted blockade of certain potassium channels at the hypoglossal motor pool is an effective strategy for reversing upper airway hypotonia and causing sustained reactivation of genioglossus throughout nonrapid eye movement and rapid eye movement sleep. These findings identify an important new direction for translational approaches to the pharmacological treatment of obstructive sleep apnea.

[Conceptual approach to formation of a modern system of medical provision].

PubMed

Belevitin, A B; Miroshnichenko, Iu V; Bunin, S A; Goriachev, A B; Krasavin, K D

2009-09-01

Within the frame of forming of a new face of medical service of the Armed Forces, were determined the principle approaches to optimization of the process of development of the system of medical supply. It was proposed to use the following principles: principle of hierarchic structuring, principle of purposeful orientation, principle of vertical task sharing, principle of horizontal task sharing, principle of complex simulation, principle of permanent perfection. The main direction of optimization of structure and composition of system of medical supply of the Armed Forces are: forming of modern institutes of medical supply--centers of support by technique and facilities on the base of central, regional storehouses, and attachment of several functions of organs of military government to them; creation of medical supply office on the base military hospitals, being basing treatment-prophylaxis institutes, in adjusted territorial zones of responsibility for the purpose of realization of complex of tasks of supplying the units and institutes, attached to them on medical support, by medical equipment. Building of medical support system is realized on three levels: Center - Military region (NAVY region) - territorial zone of responsibility.

Biomonitoring of Organophosphorus Agent Exposure by Reactivation of Cholinesterase Enzyme Based on Carbon Nanotube-Enhanced Flow-Injection Amperometric Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Dan; Wang, Jun; Smith, Jordan N.

2009-11-15

A portable, rapid, and sensitive assessment of sub-clinical organophosphorus (OPs) agent exposure based on reactivation of cholinesterase (ChE) from OP-inhibited ChE using rat saliva (in vitro) was developed using an electrochemical sensor coupled with a microflow-injection system. The sensor was based on a carbon nanotube (CNT)-modified screen printed carbon electrode (SPE), which was integrated into a flow cell. Due to the extent of inter-individual ChE activity variability, ChE biomonitoring often requires an initial base-line determination (non-inhibited) of enzyme activity which is then directly compared with activity after OP exposure. This manuscript described an alternative strategy where reactivation of the phosphorylatedmore » enzyme was exploited to enable measurement of both inhibited and baseline ChE activity (i.e. after reactivation) in the same sample. The use of CNT makes the electrochemical detection of the products from enzymatic reactions more feasible with extremely high sensitivity and at low potentials. Paraoxon was selected as a model OP compound for in vitro inhibition studies. Some experiment parameters, (e.g. inhibition and reactivation times), have been optimized such that, 92 - 95% ChE reactivation can be achieved over a broad range of ChE inhibition (5 - 94 %) with paraoxon. The extent of enzyme inhibition using this electrochemical sensor correlates well with conventional enzyme activity measurements.« less

Principled Leadership and Business Diplomacy. A Practical, Values-Based Direction for Management Development.

ERIC Educational Resources Information Center

London, Manuel

1999-01-01

Describes business diplomacy based on the Japanese concept of kyosei (working for the common good). Gives case examples of application of principled diplomacy to ethical dilemmas and suggests ways to establish an organizational culture to support principled business leadership. (SK)

Stiffness Parameter Design of Suspension Element of Under-Chassis-Equipment for A Rail Vehicle

NASA Astrophysics Data System (ADS)

Ma, Menglin; Wang, Chengqiang; Deng, Hai

2017-06-01

According to the frequency configuration requirements of the vibration of railway under-chassis-equipment, the three- dimension stiffness of the suspension elements of under-chassis-equipment is designed based on the static principle and dynamics principle. The design results of the concrete engineering case show that, compared with the design method based on the static principle, the three- dimension stiffness of the suspension elements designed by the dynamic principle design method is more uniform. The frequency and decoupling degree analysis show that the calculation frequency of under-chassis-equipment under the two design methods is basically the same as the predetermined frequency. Compared with the design method based on the static principle, the design method based on the dynamic principle is adopted. The decoupling degree can be kept high, and the coupling vibration of the corresponding vibration mode can be reduced effectively, which can effectively reduce the fatigue damage of the key parts of the hanging element.

32 CFR 776.19 - Principles.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 5 2010-07-01 2010-07-01 false Principles. 776.19 Section 776.19 National... Professional Conduct § 776.19 Principles. The Rules of this subpart are based on the following principles... exists, this subpart should be interpreted consistent with these general principles. (a) Covered...

MICROBIAL CHARACTERIZATION OF MANURE BASED PERMEABLE REACTIVE BARRIER

EPA Science Inventory

The implementation of permeable reactive barriers (PRB) provides a viable option for the remediation of contaminants of environmental significance such as dissolved metals (i.e., chromium), chlorinated solvents, and nitrate/ammonia. The designs of PRBs are usually based on the a...

Reactive Power Pricing Model Considering the Randomness of Wind Power Output

NASA Astrophysics Data System (ADS)

Dai, Zhong; Wu, Zhou

2018-01-01

With the increase of wind power capacity integrated into grid, the influence of the randomness of wind power output on the reactive power distribution of grid is gradually highlighted. Meanwhile, the power market reform puts forward higher requirements for reasonable pricing of reactive power service. Based on it, the article combined the optimal power flow model considering wind power randomness with integrated cost allocation method to price reactive power. Meanwhile, considering the advantages and disadvantages of the present cost allocation method and marginal cost pricing, an integrated cost allocation method based on optimal power flow tracing is proposed. The model realized the optimal power flow distribution of reactive power with the minimal integrated cost and wind power integration, under the premise of guaranteeing the balance of reactive power pricing. Finally, through the analysis of multi-scenario calculation examples and the stochastic simulation of wind power outputs, the article compared the results of the model pricing and the marginal cost pricing, which proved that the model is accurate and effective.

A Feasibility Study of Virtual Reality-Based Coping Skills Training for Nicotine Dependence

ERIC Educational Resources Information Center

Bordnick, Patrick S.; Traylor, Amy C.; Carter, Brian L.; Graap, Ken M.

2012-01-01

Objective: Virtual reality (VR)-based cue reactivity has been successfully used for the assessment of drug craving. Going beyond assessment of cue reactivity, a novel VR-based treatment approach for smoking cessation was developed and tested for feasibility. Method: In a randomized experiment, 10-week treatment feasibility trial, 46…

The base rate principle and the fairness principle in social judgment

PubMed Central

Cao, Jack; Banaji, Mahzarin R.

2016-01-01

Meet Jonathan and Elizabeth. One person is a doctor and the other is a nurse. Who is the doctor? When nothing else is known, the base rate principle favors Jonathan to be the doctor and the fairness principle favors both individuals equally. However, when individuating facts reveal who is actually the doctor, base rates and fairness become irrelevant, as the facts make the correct answer clear. In three experiments, explicit and implicit beliefs were measured before and after individuating facts were learned. These facts were either stereotypic (e.g., Jonathan is the doctor, Elizabeth is the nurse) or counterstereotypic (e.g., Elizabeth is the doctor, Jonathan is the nurse). Results showed that before individuating facts were learned, explicit beliefs followed the fairness principle, whereas implicit beliefs followed the base rate principle. After individuating facts were learned, explicit beliefs correctly aligned with stereotypic and counterstereotypic facts. Implicit beliefs, however, were immune to counterstereotypic facts and continued to follow the base rate principle. Having established the robustness and generality of these results, a fourth experiment verified that gender stereotypes played a causal role: when both individuals were male, explicit and implicit beliefs alike correctly converged with individuating facts. Taken together, these experiments demonstrate that explicit beliefs uphold fairness and incorporate obvious and relevant facts, but implicit beliefs uphold base rates and appear relatively impervious to counterstereotypic facts. PMID:27325760

The base rate principle and the fairness principle in social judgment.

PubMed

Cao, Jack; Banaji, Mahzarin R

2016-07-05

Meet Jonathan and Elizabeth. One person is a doctor and the other is a nurse. Who is the doctor? When nothing else is known, the base rate principle favors Jonathan to be the doctor and the fairness principle favors both individuals equally. However, when individuating facts reveal who is actually the doctor, base rates and fairness become irrelevant, as the facts make the correct answer clear. In three experiments, explicit and implicit beliefs were measured before and after individuating facts were learned. These facts were either stereotypic (e.g., Jonathan is the doctor, Elizabeth is the nurse) or counterstereotypic (e.g., Elizabeth is the doctor, Jonathan is the nurse). Results showed that before individuating facts were learned, explicit beliefs followed the fairness principle, whereas implicit beliefs followed the base rate principle. After individuating facts were learned, explicit beliefs correctly aligned with stereotypic and counterstereotypic facts. Implicit beliefs, however, were immune to counterstereotypic facts and continued to follow the base rate principle. Having established the robustness and generality of these results, a fourth experiment verified that gender stereotypes played a causal role: when both individuals were male, explicit and implicit beliefs alike correctly converged with individuating facts. Taken together, these experiments demonstrate that explicit beliefs uphold fairness and incorporate obvious and relevant facts, but implicit beliefs uphold base rates and appear relatively impervious to counterstereotypic facts.

Comparative In Vivo Effects of Hemoglobin-Based Oxygen Carriers (HBOC) with Varying Prooxidant and Physiological Reactivity.

PubMed

Toma, Vlad Al; Farcaș, Anca D; Roman, Ioana; Sevastre, Bogdan; Hathazi, Denisa; Scurtu, Florina; Damian, Grigore; Silaghi-Dumitrescu, Radu

2016-01-01

A series of hemoglobin-based oxygen carrier candidates (HBOC), previously noted for their differences in prooxidative and physiological reactivity, were compared in terms of the negative effects displayed upon injection in Wistar rats. At the concentrations tested, antioxidant strategies based on albumin as well as based on rubrerythrin appear to offer observable physiological advantages.

A comprehensive approach to reactive power scheduling in restructured power systems

NASA Astrophysics Data System (ADS)

Shukla, Meera

Financial constraints, regulatory pressure, and need for more economical power transfers have increased the loading of interconnected transmission systems. As a consequence, power systems have been operated close to their maximum power transfer capability limits, making the system more vulnerable to voltage instability events. The problem of voltage collapse characterized by a severe local voltage depression is generally believed to be associated with inadequate VAr support at key buses. The goal of reactive power planning is to maintain a high level of voltage security, through installation of properly sized and located reactive sources and their optimal scheduling. In case of vertically-operated power systems, the reactive requirement of the system is normally satisfied by using all of its reactive sources. But in case of different scenarios of restructured power systems, one may consider a fixed amount of exchange of reactive power through tie lines. Reviewed literature suggests a need for optimal scheduling of reactive power generation for fixed inter area reactive power exchange. The present work proposed a novel approach for reactive power source placement and a novel approach for its scheduling. The VAr source placement technique was based on the property of system connectivity. This is followed by development of optimal reactive power dispatch formulation which facilitated fixed inter area tie line reactive power exchange. This formulation used a Line Flow-Based (LFB) model of power flow analysis. The formulation determined the generation schedule for fixed inter area tie line reactive power exchange. Different operating scenarios were studied to analyze the impact of VAr management approach for vertically operated and restructured power systems. The system loadability, losses, generation and the cost of generation were the performance measures to study the impact of VAr management strategy. The novel approach was demonstrated on IEEE 30 bus system.

A Model-based Approach to Reactive Self-Configuring Systems

NASA Technical Reports Server (NTRS)

Williams, Brian C.; Nayak, P. Pandurang

1996-01-01

This paper describes Livingstone, an implemented kernel for a self-reconfiguring autonomous system, that is reactive and uses component-based declarative models. The paper presents a formal characterization of the representation formalism used in Livingstone, and reports on our experience with the implementation in a variety of domains. Livingstone's representation formalism achieves broad coverage of hybrid software/hardware systems by coupling the concurrent transition system models underlying concurrent reactive languages with the discrete qualitative representations developed in model-based reasoning. We achieve a reactive system that performs significant deductions in the sense/response loop by drawing on our past experience at building fast prepositional conflict-based algorithms for model-based diagnosis, and by framing a model-based configuration manager as a prepositional, conflict-based feedback controller that generates focused, optimal responses. Livingstone automates all these tasks using a single model and a single core deductive engine, thus making significant progress towards achieving a central goal of model-based reasoning. Livingstone, together with the HSTS planning and scheduling engine and the RAPS executive, has been selected as the core autonomy architecture for Deep Space One, the first spacecraft for NASA's New Millennium program.

Emergent features and perceptual objects: re-examining fundamental principles in analogical display design.

PubMed

Holt, Jerred; Bennett, Kevin B; Flach, John M

2015-01-01

Two sets of design principles for analogical visual displays, based on the concepts of emergent features and perceptual objects, are described. An interpretation of previous empirical findings for three displays (bar graph, polar graphic, alphanumeric) is provided from both perspectives. A fourth display (configural coordinate) was designed using principles of ecological interface design (i.e. direct perception). An experiment was conducted to evaluate performance (accuracy and latency of state identification) with these four displays. Numerous significant effects were obtained and a clear rank ordering of performance emerged (from best to worst): configural coordinate, bar graph, alphanumeric and polar graphic. These findings are consistent with principles of design based on emergent features; they are inconsistent with principles based on perceptual objects. Some limitations of the configural coordinate display are discussed and a redesign is provided. Practitioner Summary: Principles of ecological interface design, which emphasise the quality of very specific mappings between domain, display and observer constraints, are described; these principles are applicable to the design of all analogical graphical displays.

Carbon cluster formation during thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and 1,3,5-triamino-2,4,6-trinitrobenzene high explosives from ReaxFF reactive molecular dynamics simulations.

PubMed

Zhang, Luzheng; Zybin, Sergey V; van Duin, Adri C T; Dasgupta, Siddharth; Goddard, William A; Kober, Edward M

2009-10-08

We report molecular dynamics (MD) simulations using the first-principles-based ReaxFF reactive force field to study the thermal decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) at various densities and temperatures. TATB is known to produce a large amount (15-30%) of high-molecular-weight carbon clusters, whereas detonation of nitramines such as HMX and RDX (1,3,5-trinitroperhydro-1,3,5-triazine) generate predominantly low-molecular-weight products. In agreement with experimental observation, these simulations predict that TATB decomposition quickly (by 30 ps) initiates the formation of large carbonaceous clusters (more than 4000 amu, or approximately 15-30% of the total system mass), and HMX decomposition leads almost exclusively to small-molecule products. We find that HMX decomposes readily on this time scale at lower temperatures, for which the decomposition rate of TATB is about an order of magnitude slower. Analyzing the ReaxFF MD results leads to the detailed atomistic structure of this carbon-rich phase of TATB and allows characterization of the kinetics and chemistry related to this phase and their dependence on system density and temperature. The carbon-rich phase formed from TATB contains mainly polyaromatic rings with large oxygen content, leading to graphitic regions. We use these results to describe the initial reaction steps of thermal decomposition of HMX and TATB in terms of the rates for forming primary and secondary products, allowing comparison to experimentally derived models. These studies show that MD using the ReaxFF reactive force field provides detailed atomistic information that explains such macroscopic observations as the dramatic difference in carbon cluster formation between TATB and HMX. This shows that ReaxFF MD captures the fundamental differences in the mechanisms of such systems and illustrates how the ReaxFF may be applied to model complex chemical phenomena in energetic materials. The studies here illustrate this for modestly sized systems and modest periods; however, ReaxFF calculations of reactive processes have already been reported on systems with approximately 10(6) atoms. Thus, with suitable computational facilities, one can study the atomistic level chemical processes in complex systems under extreme conditions.

Voltage control for a wind power plant based on the available reactive current of a DFIG and its impacts on the point of interconnection

DOE PAGES

Usman, Yasir; Kim, Jinho; Muljadi, Eduard; ...

2016-01-01

Wake effects cause wind turbine generators (WTGs) within a wind power plant (WPP) to produce different levels of active power and subsequent reactive power capabilities. Further, the impedance between a WTG and the point of interconnection (POI)-which depends on the distance between them-impacts the WPP's reactive power injection capability at the POI. This paper proposes a voltage control scheme for a WPP based on the available reactive current of the doubly-fed induction generators (DFIGs) and its impacts on the POI to improve the reactive power injection capability of the WPP. In this paper, a design strategy for modifying the gainmore » of DFIG controller is suggested and the comprehensive properties of these control gains are investigated. In the proposed scheme, the WPP controller, which operates in a voltage control mode, sends the command signal to the DFIGs based on the voltage difference at the POI. The DFIG controllers, which operate in a voltage control mode, employ a proportional controller with a limiter. The gain of the proportional controller is adjusted depending on the available reactive current of the DFIG and the series impedance between the DFIG and the POI. The performance of the proposed scheme is validated for various disturbances such as a reactive load connection and grid fault using an EMTP-RV simulator. Furthermore, simulation results demonstrate that the proposed scheme promptly recovers the POI voltage by injecting more reactive power after a disturbance than the conventional scheme.« less

Performance evaluation of the FDA-approved Determine™ HIV-1/2 Ag/Ab Combo assay using plasma and whole blood specimens.

PubMed

Masciotra, Silvina; Luo, Wei; Westheimer, Emily; Cohen, Stephanie E; Gay, Cynthia L; Hall, Laura; Pan, Yi; Peters, Philip J; Owen, S Michele

2017-06-01

The Determine™ HIV-1/2 Ag/Ab Combo (DC) rapid test can identify HIV-1 infection earlier than rapid antibody-only tests in plasma specimens. We compared the performance of DC with a laboratory-based antigen/antibody (Ag/Ab) combo assay in plasma and evaluated antigen reactivity in whole blood specimens. We tested by DC 508 plasma specimens collected in a prospective study and 107 sequential plasma and simulated whole blood specimens from 20 seroconversion panels. Previous results using the ARCHITECT (ARC) Ag/Ab combo assay were compared to DC results. In seroconversion panels, the days from the first HIV1 RNA-positive test to first DC-reactive in plasma and whole blood was compared. McNemar's and Wilcoxon signed rank tests were used for statistical analysis. Of 415 HIV-positive samples, ARC detected 396 (95.4%) and DC 337 (81.2%) (p<0.0001). DC was reactive in 50.0% of ARC-reactive/MS-negative, 78.6% of ARC-reactive/MS-indeterminate, and 99.6% of ARC-reactive/MS-HIV-1-positive or -undifferentiated specimens. DC antigen reactivity was higher among ARC-reactive/MS-negative than MS-indeterminate samples. In 20 HIV-1 seroconversion panels, there was a significant difference between DC reactivity in plasma (91.1%) and whole blood (56.4%) (p<0.0001). DC with whole blood showed a significant delay in reactivity compared to plasma (p=0.008). In plasma, DC was significantly less sensitive than an instrumented laboratory-based Ag/Ab combo assay. DC in plasma was significantly more sensitive compared to whole blood in early HIV-1 infections. With the U.S. laboratory-based diagnostic algorithm, DC as the first step would likely miss a high proportion of HIV-1 infections in early stages of seroconversion. Published by Elsevier B.V.

Applying behavior analysis to school violence and discipline problems: Schoolwide positive behavior support

PubMed Central

Anderson, Cynthia M.; Kincaid, Donald

2005-01-01

School discipline is a growing concern in the United States. Educators frequently are faced with discipline problems ranging from infrequent but extreme problems (e.g., shootings) to less severe problems that occur at high frequency (e.g., bullying, insubordination, tardiness, and fighting). Unfortunately, teachers report feeling ill prepared to deal effectively with discipline problems in schools. Further, research suggests that many commonly used strategies, such as suspension, expulsion, and other reactive strategies, are not effective for ameliorating discipline problems and may, in fact, make the situation worse. The principles and technology of behavior analysis have been demonstrated to be extremely effective for decreasing problem behavior and increasing social skills exhibited by school children. Recently, these principles and techniques have been applied at the level of the entire school, in a movement termed schoolwide positive behavior support. In this paper we review the tenets of schoolwide positive behavior support, demonstrating the relation between this technology and applied behavior analysis. PMID:22478439

Pumpable/injectable phosphate-bonded ceramics

DOEpatents

Singh, Dileep; Wagh, Arun S.; Perry, Lamar; Jeong, Seung-Young

2001-01-01

A pumpable ceramic composition is provided comprising an inorganic oxide, potassium phosphate, and an oxide coating material. Also provided is a method for preparing pumpable ceramic-based waste forms comprising selecting inorganic oxides based on solubility, surface area and morphology criteria; mixing the selected oxides with phosphate solution and waste to form a first mixture; combining an additive to the first mixture to create a second mixture; adding water to the second mixture to create a reactive mixture; homogenizing the reactive mixture; and allowing the reactive mixture to cure.

A Principles-Based Approach to Teaching International Financial Reporting Standards (IFRS)

ERIC Educational Resources Information Center

Persons, Obeua

2014-01-01

This article discusses the principles-based approach that emphasizes a "why" question by using the International Accounting Standards Board (IASB) "Conceptual Framework for Financial Reporting" to question and understand the basis for specific differences between IFRS and U.S. generally accepted accounting principles (U.S.…

Differential Targeting of Unpaired Bases within Duplex DNA by the Natural Compound Clerocidin: A Valuable Tool to Dissect DNA Secondary Structure

PubMed Central

Nadai, Matteo; Palù, Giorgio; Palumbo, Manlio; Richter, Sara N.

2012-01-01

Non-canonical DNA structures have been postulated to mediate protein-nucleic acid interactions and to function as intermediates in the generation of frame-shift mutations when errors in DNA replication occur, which result in a variety of diseases and cancers. Compounds capable of binding to non-canonical DNA conformations may thus have significant diagnostic and therapeutic potential. Clerocidin is a natural diterpenoid which has been shown to selectively react with single-stranded bases without targeting the double helix. Here we performed a comprehensive analysis on several non-canonical DNA secondary structures, namely mismatches, nicks, bulges, hairpins, with sequence variations in both the single-stranded region and the double-stranded flanking segment. By analysis of clerocidin reactivity, we were able to identify the exposed reactive residues which provided information on both the secondary structure and the accessibility of the non-paired sites. Mismatches longer than 1 base were necessary to be reached by clerocidin reactive groups, while 1-base nicks were promptly targeted by clerocidin; in hairpins, clerocidin reactivity increased with the length of the hairpin loop, while, interestingly, reactivity towards bulges reached a maximum in 3-base-long bulges and declined in longer bulges. Electrophoretic mobility shift analysis demonstrated that bulges longer than 3 bases (i.e. 5- and 7-bases) folded or stacked on the duplex region therefore being less accessible by the compound. Clerocidin thus represents a new valuable diagnostic tool to dissect DNA secondary structures. PMID:23285245

Differential targeting of unpaired bases within duplex DNA by the natural compound clerocidin: a valuable tool to dissect DNA secondary structure.

PubMed

Nadai, Matteo; Palù, Giorgio; Palumbo, Manlio; Richter, Sara N

2012-01-01

Non-canonical DNA structures have been postulated to mediate protein-nucleic acid interactions and to function as intermediates in the generation of frame-shift mutations when errors in DNA replication occur, which result in a variety of diseases and cancers. Compounds capable of binding to non-canonical DNA conformations may thus have significant diagnostic and therapeutic potential. Clerocidin is a natural diterpenoid which has been shown to selectively react with single-stranded bases without targeting the double helix. Here we performed a comprehensive analysis on several non-canonical DNA secondary structures, namely mismatches, nicks, bulges, hairpins, with sequence variations in both the single-stranded region and the double-stranded flanking segment. By analysis of clerocidin reactivity, we were able to identify the exposed reactive residues which provided information on both the secondary structure and the accessibility of the non-paired sites. Mismatches longer than 1 base were necessary to be reached by clerocidin reactive groups, while 1-base nicks were promptly targeted by clerocidin; in hairpins, clerocidin reactivity increased with the length of the hairpin loop, while, interestingly, reactivity towards bulges reached a maximum in 3-base-long bulges and declined in longer bulges. Electrophoretic mobility shift analysis demonstrated that bulges longer than 3 bases (i.e. 5- and 7-bases) folded or stacked on the duplex region therefore being less accessible by the compound. Clerocidin thus represents a new valuable diagnostic tool to dissect DNA secondary structures.

An approach to evaluating reactive airborne wind shear systems

NASA Technical Reports Server (NTRS)

Gibson, Joseph P., Jr.

1992-01-01

An approach to evaluating reactive airborne windshear detection systems was developed to support a deployment study for future FAA ground-based windshear detection systems. The deployment study methodology assesses potential future safety enhancements beyond planned capabilities. The reactive airborne systems will be an integral part of planned windshear safety enhancements. The approach to evaluating reactive airborne systems involves separate analyses for both landing and take-off scenario. The analysis estimates the probability of effective warning considering several factors including NASA energy height loss characteristics, reactive alert timing, and a probability distribution for microburst strength.

Synthesis of carbon-11, fluorine-18, and nitrogen-13 labeled radiotracers for biomedical applications. Nuclear Science Series: Nuclear Medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, J.S.; Wolf, A.P.

1982-09-01

Carbon 11, Fluorine 18, and Nitrogen 13-labeled radiotracers are reviewed from the standpoint of synthetic organic chemistry while keeping in perspective the necessity of integrating the organic chemistry with the design and ultimate application of the radiotracer. The reactions used, the principles used to adapt these reactions to labeling with short-lived radionuclides, and the concepts of chemical reactivity form the framework upon which synthetic strategies for short-lived radiotracers are developed. Potentially new routes are suggested which may be applied to problems in labeling organic molecules. (ACR)

Contemporary screening approaches to reaction discovery and development.

PubMed

Collins, Karl D; Gensch, Tobias; Glorius, Frank

2014-10-01

New organic reactivity has often been discovered by happenstance. Several recent research efforts have attempted to leverage this to discover new reactions. In this Review, we attempt to unify reported approaches to reaction discovery on the basis of the practical and strategic principles applied. We concentrate on approaches to reaction discovery as opposed to reaction development, though conceptually groundbreaking approaches to identifying efficient catalyst systems are also considered. Finally, we provide a critical overview of the utility and application of the reported methods from the perspective of a synthetic chemist, and consider the future of high-throughput screening in reaction discovery.

Tip-induced reduction of the resonant tunneling current on semiconductor surfaces.

PubMed

Jelínek, Pavel; Svec, Martin; Pou, Pablo; Perez, Ruben; Cháb, Vladimír

2008-10-24

We report scanning tunneling microscope measurements showing a substantial decrease of the current, almost to zero, on the Si(111)-(7x7) reconstruction in the near-to-contact region under low bias conditions. First principles simulations for the tip-sample interaction and transport calculations show that this effect is driven by the substantial local modification of the atomic and electronic structure of the surface. The chemical reactivity of the adatom dangling bond states that dominate the electronic density of states close to the Fermi level and their spatial localization result in a strong modification of the electronic current.

STUDIES ON THE SENSITIZATION OF ANIMALS WITH SIMPLE CHEMICAL COMPOUNDS

PubMed Central

Landsteiner, K.; Di Somma, A. A.

1940-01-01

Sensitization of guinea pigs to picric acid was obtained by application of oil solutions to the skin, preferably on inflamed sites or by treatment with a compound of picric acid with n-butyl-p-aminobenzoate. The lesions obtained in sensitive animals on superficial administration bore resemblance to human eczema. It seems probable that picric acid sensitization is an instance where a substance does not sensitize directly but after conversion into a more reactive compound, a principle which should be of wider application to instances where the original substance does not readily form conjugates. PMID:19871030

The Hitchhiker's Guide to Flow Chemistry ∥.

PubMed

Plutschack, Matthew B; Pieber, Bartholomäus; Gilmore, Kerry; Seeberger, Peter H

2017-09-27

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

Chemical protein synthesis: Inventing synthetic methods to decipher how proteins work.

PubMed

Kent, Stephen

2017-09-15

Total chemical synthesis of proteins has been rendered practical by the chemical ligation principle: chemoselective condensation of unprotected peptide segments equipped with unique, mutually reactive functional groups, enabled by formation of a non-native replacement for the peptide bond. Ligation chemistries are briefly described, including native chemical ligation - thioester-mediated, amide-forming reaction at Xaa-Cys sites - and its extensions. Case studies from the author's own works are used to illustrate the utility and applications of chemical protein synthesis. Selected recent developments in the field are briefly discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reactivating dynamics for the susceptible-infected-susceptible model: a simple method to simulate the absorbing phase

NASA Astrophysics Data System (ADS)

Macedo-Filho, A.; Alves, G. A.; Costa Filho, R. N.; Alves, T. F. A.

2018-04-01

We investigated the susceptible-infected-susceptible model on a square lattice in the presence of a conjugated field based on recently proposed reactivating dynamics. Reactivating dynamics consists of reactivating the infection by adding one infected site, chosen randomly when the infection dies out, avoiding the dynamics being trapped in the absorbing state. We show that the reactivating dynamics can be interpreted as the usual dynamics performed in the presence of an effective conjugated field, named the reactivating field. The reactivating field scales as the inverse of the lattice number of vertices n, which vanishes at the thermodynamic limit and does not affect any scaling properties including ones related to the conjugated field.

Computer-Based Training Development and Guidance for the Army’s Unmanned Aviation Systems Maintenance Training Division

DTIC Science & Technology

2017-08-01

principles for effective Computer-Based Training (CBT) that can be applied broadly to Army courses to build and evaluate exemplar CBT for Army advanced...individual training courses. To assist cadre who do not have a dedicated instructional design team, the Computer-Based Training Principles Guide was...document is the resulting contents, organization, and presentation style of the Computer- Based Training Principles Guide and its companion User’s Guide

Insurance principles and the design of prospective payment systems.

PubMed

Ellis, R P; McGuire, T G

1988-09-01

This paper applies insurance principles to the issues of optimal outlier payments and designation of peer groups in Medicare's case-based prospective payment system for hospital care. Arrow's principle that full insurance after a deductible is optimal implies that, to minimize hospital risk, outlier payments should be based on hospital average loss per case rather than, as at present, based on individual case-level losses. The principle of experience rating implies defining more homogenous peer groups for the purpose of figuring average cost. The empirical significance of these results is examined using a sample of 470,568 discharges from 469 hospitals.

Free radicals, reactive oxygen species, oxidative stress and its classification.

PubMed

Lushchak, Volodymyr I

2014-12-05

Reactive oxygen species (ROS) initially considered as only damaging agents in living organisms further were found to play positive roles also. This paper describes ROS homeostasis, principles of their investigation and technical approaches to investigate ROS-related processes. Especial attention is paid to complications related to experimental documentation of these processes, their diversity, spatiotemporal distribution, relationships with physiological state of the organisms. Imbalance between ROS generation and elimination in favor of the first with certain consequences for cell physiology has been called "oxidative stress". Although almost 30years passed since the first definition of oxidative stress was introduced by Helmut Sies, to date we have no accepted classification of oxidative stress. In order to fill up this gape here classification of oxidative stress based on its intensity is proposed. Due to that oxidative stress may be classified as basal oxidative stress (BOS), low intensity oxidative stress (LOS), intermediate intensity oxidative stress (IOS), and high intensity oxidative stress (HOS). Another classification of potential interest may differentiate three categories such as mild oxidative stress (MOS), temperate oxidative stress (TOS), and finally severe (strong) oxidative stress (SOS). Perspective directions of investigations in the field include development of sophisticated classification of oxidative stresses, accurate identification of cellular ROS targets and their arranged responses to ROS influence, real in situ functions and operation of so-called "antioxidants", intracellular spatiotemporal distribution and effects of ROS, deciphering of molecular mechanisms responsible for cellular response to ROS attacks, and ROS involvement in realization of normal cellular functions in cellular homeostasis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Siting and sizing of distributed generators based on improved simulated annealing particle swarm optimization.

PubMed

Su, Hongsheng

2017-12-18

Distributed power grids generally contain multiple diverse types of distributed generators (DGs). Traditional particle swarm optimization (PSO) and simulated annealing PSO (SA-PSO) algorithms have some deficiencies in site selection and capacity determination of DGs, such as slow convergence speed and easily falling into local trap. In this paper, an improved SA-PSO (ISA-PSO) algorithm is proposed by introducing crossover and mutation operators of genetic algorithm (GA) into SA-PSO, so that the capabilities of the algorithm are well embodied in global searching and local exploration. In addition, diverse types of DGs are made equivalent to four types of nodes in flow calculation by the backward or forward sweep method, and reactive power sharing principles and allocation theory are applied to determine initial reactive power value and execute subsequent correction, thus providing the algorithm a better start to speed up the convergence. Finally, a mathematical model of the minimum economic cost is established for the siting and sizing of DGs under the location and capacity uncertainties of each single DG. Its objective function considers investment and operation cost of DGs, grid loss cost, annual purchase electricity cost, and environmental pollution cost, and the constraints include power flow, bus voltage, conductor current, and DG capacity. Through applications in an IEEE33-node distributed system, it is found that the proposed method can achieve desirable economic efficiency and safer voltage level relative to traditional PSO and SA-PSO algorithms, and is a more effective planning method for the siting and sizing of DGs in distributed power grids.

PERFORMANCE EVALUATION OF A CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION

EPA Science Inventory

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION AT A FORMER SWINE CAFO

EPA Science Inventory

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

Neuro-estimator based GMC control of a batch reactive distillation.

PubMed

Prakash, K J Jithin; Patle, Dipesh S; Jana, Amiya K

2011-07-01

In this paper, an artificial neural network (ANN)-based nonlinear control algorithm is proposed for a simulated batch reactive distillation (RD) column. In the homogeneously catalyzed reactive process, an esterification reaction takes place for the production of ethyl acetate. The fundamental model has been derived incorporating the reaction term in the model structure of the nonreactive distillation process. The process operation is simulated at the startup phase under total reflux conditions. The open-loop process dynamics is also addressed running the batch process at the production phase under partial reflux conditions. In this study, a neuro-estimator based generic model controller (GMC), which consists of an ANN-based state predictor and the GMC law, has been synthesized. Finally, this proposed control law has been tested on the representative batch reactive distillation comparing with a gain-scheduled proportional integral (GSPI) controller and with its ideal performance (ideal GMC). Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Fluorescent-protein-based probes: general principles and practices.

PubMed

Ai, Hui-Wang

2015-01-01

An important application of fluorescent proteins is to derive genetically encoded fluorescent probes that can actively respond to cellular dynamics such as pH change, redox signaling, calcium oscillation, enzyme activities, and membrane potential. Despite the large diverse group of fluorescent-protein-based probes, a few basic principles have been established and are shared by most of these probes. In this article, the focus is on these general principles and strategies that guide the development of fluorescent-protein-based probes. A few examples are provided in each category to illustrate the corresponding principles. Since these principles are quite straightforward, others may adapt them to create fluorescent probes for their own interest. Hopefully, the development of the ever-growing family of fluorescent-protein-based probes will no longer be limited to a small number of laboratories specialized in senor development, leading to the situation that biological studies will be bettered assisted by genetically encoded sensors.

LC-MS-based characterization of the peptide reactivity of chemicals to improve the in vitro prediction of the skin sensitization potential.

PubMed

Natsch, Andreas; Gfeller, Hans

2008-12-01

A key step in the skin sensitization process is the formation of a covalent adduct between skin sensitizers and endogenous proteins and/or peptides in the skin. Based on this mechanistic understanding, there is a renewed interest in in vitro assays to determine the reactivity of chemicals toward peptides in order to predict their sensitization potential. A standardized peptide reactivity assay yielded a promising predictivity. This published assay is based on high-performance liquid chromatography with ultraviolet detection to quantify peptide depletion after incubation with test chemicals. We had observed that peptide depletion may be due to either adduct formation or peptide oxidation. Here we report a modified assay based on both liquid chromatography-mass spectrometry (LC-MS) analysis and detection of free thiol groups. This approach allows simultaneous determination of (1) peptide depletion, (2) peptide oxidation (dimerization), (3) adduct formation, and (4) thiol reactivity and thus generates a more detailed characterization of the reactivity of a molecule. Highly reactive molecules are further discriminated with a kinetic measure. The assay was validated on 80 chemicals. Peptide depletion could accurately be quantified both with LC-MS detection and depletion of thiol groups. The majority of the moderate/strong/extreme sensitizers formed detectable peptide adducts, but many sensitizers were also able to catalyze peptide oxidation. Whereas adduct formation was only observed for sensitizers, this oxidation reaction was also observed for two nonsensitizing fragrance aldehydes, indicating that peptide depletion might not always be regarded as sufficient evidence for rating a chemical as a sensitizer. Thus, this modified assay gives a more informed view of the peptide reactivity of chemicals to better predict their sensitization potential.

Understanding the Reactivity of Lunar Dust for Future Lunar Missions

NASA Technical Reports Server (NTRS)

Wallace, W. T.; Jeevarajan, A. S.; Taylor, L. A.

2010-01-01

Fluorescence and EPR can be used to measure the reactivity of lunar soil. Lunar soil is highly activated by grinding. Reactivity is dependent upon soil maturity and locale. Maturity is based on the amount of nanophase iron (np-Fe) in a soil relative to the total iron (FeO). Lunar soil activity ia a direct function of the amount of np-Fe present. Reactive soil can be "deactivated" by humid atmosphere.

An exploratory study of live vs. web-based delivery of a phlebotomy program.

PubMed

Fydryszewski, Nadine A; Scanlan, Craig; Guiles, H Jesse; Tucker, Ann

2010-01-01

Changes in student population and increased Web-based education offerings provided the impetus to assess pedagogy, cognitive outcomes and perceptions of course quality. This study explored cognitive outcomes and students' perception of course quality related to the Seven Principles for Good Practice in Undergraduate Education between live classroom delivery, compared to a Web-based delivery of a phlebotomy program. Quasi-experimental; students self-selected to enroll in live or Web-based program. For cognitive outcomes, no significant difference was found between the groups. Student perception of course quality differed only for Principle One (student-instructor contact). Students in the live classroom rated Principle One higher for the Part I course compared to the Web-based group. For the Part II course, there was no significant difference in perception of course quality related to any of the Seven Principles. The more constructivist pedagogy in the Part II course did not improve cognitive outcomes however, it may have contributed to knowledge retention. The live group rated Principle One in the Part II course evaluation relatively the same as they did for the Part I course evaluation. However, the Web-based group rated Principle One considerable higher for the Part II course than for Part I course. Future studies with a larger sample could explore improved course quality assessment instruments.

PyGlobal: A toolkit for automated compilation of DFT-based descriptors.

PubMed

Nath, Shilpa R; Kurup, Sudheer S; Joshi, Kaustubh A

2016-06-15

Density Functional Theory (DFT)-based Global reactivity descriptor calculations have emerged as powerful tools for studying the reactivity, selectivity, and stability of chemical and biological systems. A Python-based module, PyGlobal has been developed for systematically parsing a typical Gaussian outfile and extracting the relevant energies of the HOMO and LUMO. Corresponding global reactivity descriptors are further calculated and the data is saved into a spreadsheet compatible with applications like Microsoft Excel and LibreOffice. The efficiency of the module has been accounted by measuring the time interval for randomly selected Gaussian outfiles for 1000 molecules. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Extremum Seeking Control of Smart Inverters for VAR Compensation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arnold, Daniel; Negrete-Pincetic, Matias; Stewart, Emma

2015-09-04

Reactive power compensation is used by utilities to ensure customer voltages are within pre-defined tolerances and reduce system resistive losses. While much attention has been paid to model-based control algorithms for reactive power support and Volt Var Optimization (VVO), these strategies typically require relatively large communications capabilities and accurate models. In this work, a non-model-based control strategy for smart inverters is considered for VAR compensation. An Extremum Seeking control algorithm is applied to modulate the reactive power output of inverters based on real power information from the feeder substation, without an explicit feeder model. Simulation results using utility demand informationmore » confirm the ability of the control algorithm to inject VARs to minimize feeder head real power consumption. In addition, we show that the algorithm is capable of improving feeder voltage profiles and reducing reactive power supplied by the distribution substation.« less

Principles of Instruction: Research-Based Strategies That All Teachers Should Know

ERIC Educational Resources Information Center

Rosenshine, Barak

2012-01-01

This article presents 10 research-based principles of instruction, along with suggestions for classroom practice. These principles come from three sources: (a) research in cognitive science, (b) research on master teachers, and (c) research on cognitive supports. Each is briefly explained in this article. Even though these are three very different…

Site reactivity in the free radicals induced damage to leucine residues: a theoretical study.

PubMed

Medina, M E; Galano, A; Alvarez-Idaboy, J R

2015-02-21

Several recent computational studies have tried to explain the observed selectivity in radical damage to proteins. In this work we use Density Functional Theory and Transition State Theory including tunnelling corrections, reaction path degeneracy, the effect of diffusion, and the role of free radicals to get further insights into this important topic. The reaction between a leucine derivative and free radicals of biological significance, in aqueous and lipid media, has been investigated. Both thermochemical and kinetic analyses, in both hydrophilic and hydrophobic environments, have been carried out. DPPH, ˙OOH, ˙OOCH3, ˙OOCH2Cl, ˙OOCHCl2 and ˙OOCHCH2 radicals do not react with the target molecule. The reactions are proposed to be kinetically controlled. The leucine gamma site was the most reactive for the reactions with ˙N3, ˙OOCCl3, ˙OCH3, ˙OCH2Cl, and ˙OCHCl2 radicals, with rate constants equal to 1.97 × 10(5), 3.24 × 10(4), 6.68 × 10(5), 5.98 × 10(6) and 8.87 × 10(8) M(-1) s(-1), respectively, in aqueous solution. The ˙Cl, ˙OH and ˙OCCl3 radicals react with leucine at the beta, gamma, and delta positions at rates close to the diffusion limit with the alpha position which is the slowest path and the most thermodynamically favored. The presented results confirm that the Bell-Evans-Polanyi principle does not apply for the reactions between amino acid residues and free radicals. Regarding the influence of the environment on the reactivity of the studied series of free radicals towards leucine residues, it is concluded that hydrophilic media slightly lower the reactivity of the studied radicals, compared to hydrophobic ones, albeit the trends in reactivity are very similar.

A comparison of reactivating and therapeutic efficacy of bispyridinium acetylcholinesterase reactivator KR-22934 with the oxime K203 and commonly used oximes (obidoxime, trimedoxime, HI-6) in tabun-poisoned rats and mice.

PubMed

Kassa, Jiri; Karasova, Jana Zdarova; Pavlikova, Ruzena; Musilek, Kamil; Kuca, Kamil; Bajgar, Jiri; Jung, Young-Sik

2011-03-01

The potency of bispyridinium acetylcholinesterase reactivator KR-22934 in reactivating tabun-inhibited acetylcholinesterase and reducing tabun-induced lethal toxic effects was compared with the oxime K203 and commonly used oximes. Studies determining percentage of reactivation of tabun-inhibited blood and tissue acetylcholinesterase in rats showed that the reactivating efficacy of KR-22934 was slightly higher than the reactivating efficacy of K203 and roughly corresponded to the reactivating efficacy of obidoxime and trimedoxime in blood and diaphragm. On the other hand, the oxime KR-22934 was not able to reactivate tabun-inhibited acetylcholinesterase in the brain. The therapeutic efficacy of all oximes studied approximately corresponded to their reactivating efficacy. Based on the results, one can conclude that the oxime KR-22934 is not suitable for the replacement of commonly used oximes for the antidotal treatment of tabun poisoning in spite of its potency to reactivate tabun-inhibited acetylcholinesterase in the peripheral compartment (blood, diaphragm).

Intercomparison of OH and OH reactivity measurements in a high isoprene and low NO environment during the Southern Oxidant and Aerosol Study (SOAS)

NASA Astrophysics Data System (ADS)

Sanchez, Dianne; Jeong, Daun; Seco, Roger; Wrangham, Ian; Park, Jeong-Hoo; Brune, William H.; Koss, Abigail; Gilman, Jessica; de Gouw, Joost; Misztal, Pawel; Goldstein, Allen; Baumann, Karsten; Wennberg, Paul O.; Keutsch, Frank N.; Guenther, Alex; Kim, Saewung

2018-02-01

We intercompare OH and OH reactivity datasets from two different techniques, chemical ionization mass spectrometry (CIMS) and laser-induced fluorescence (LIF) in a high isoprene and low NO environment in a southeastern US forest during the Southern Oxidant and Aerosol Study (SOAS). An LIF instrument measured OH and OH reactivity at the top of a tower, a CIMS instrument measured OH at the top of the tower, and a CIMS based comparative reactivity method (CRM-CIMS) instrument deployed at the base of the tower measured OH reactivity. Averaged diel variations of OH and OH reactivity from these datasets agree within analytical uncertainty and correlations of LIF versus CIMS for OH and OH reactivity have slopes of 0.65 and 0.97, respectively. However, there are systematic differences between the measurement datasets. The CRM-CIMS measurements of OH reactivity were ∼16% lower than those by the LIF technique in the late afternoon. We speculate that it is caused by losses in the sampling line down to the CRM-CIMS instrument. On the other hand, we could not come up with a reasonable explanation for the difference in the LIF and CIMS OH datasets for early morning and late afternoon when OH is below 1 × 106 molecules cm-3. Nonetheless, results of this intercomparison exercise strengthen previous publications from the field site on OH concentrations and atmospheric reactivity.

Insights into the Li Intercalation and SEI Formation on LiSi Nanoclusters

DOE PAGES

Hankins, Kie; Soto, Fernando A.; Balbuena, Perla B.

2017-01-01

We report a first-principles atomic level assessment of the lithiation and reactivity of pre-lithiated Si clusters. Density functional theory formation energy calculations reveal that the pre-lithiated Li 16Si 16 cluster exposed to two different Li fluxes can store Li between the concentrations of Li 2.5Si and Li 3.5Si. This increase in storage capacity is attributed to the start of an amorphization process in the cluster, and more importantly these results show that the intercalation reaction can be controlled by the flux of the Li-ions. However, in a real battery, the lithiation of the anode occurs simultaneously to the electrode-electrolyte reactions.more » Here we simulate the solid-electrolyte interphase (SEI) formation and simultaneous lithiation of a Li 16Si 16 cluster in contact with two different electrolyte solutions: one with pure ethylene carbonate (EC), and another with a 1 M solution of LiPF 6 in EC. Our ab initio molecular dynamics simulations show that the solvent and salt are decomposed leading to the initial stages of the SEI layer formation and large part of the added Li becomes part of the SEI. Interestingly, the pure EC solution results in lower storage capacity and higher reactivity, whereas the presence of the salt causes the opposite effect: higher lithiation and reduced reactivity.« less

Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Särhammar, Erik, E-mail: erik.sarhammar@angstrom.uu.se; Berg, Sören; Nyberg, Tomas

2014-07-01

This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition ratemore » from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.« less

A novel and simple ORAC methodology based on the interaction of Pyrogallol Red with peroxyl radicals.

PubMed

López-Alarcón, C; Lissi, E

2006-09-01

Oxygen radicals absorbance capacities (ORAC) indexes are frequently employed to characterize the radical trapping capacity of pure compounds and their complex mixtures. A drawback of ORAC values obtained using phycoerythrin, fluorescein (FL) or c-phycocyanin as targets, makes it possible to conclude that for very reactive compounds they are much more related to stoichiometric factors than to the reactivity of the tested compound. In the present paper, we propose a simple methodology, based on the bleaching of Pyrogallol Red (PGR) absorbance that provides ORAC indexes that are almost exclusively determined by the reactivity of the tested compounds. This difference is due to the high reactivity of PGR and the high concentrations of this compound employed in the experiments.

The Experience of Daily Hassles, Cardiovascular Reactivity and Adolescent Risk Taking and Self-Esteem

ERIC Educational Resources Information Center

Vermeersch, Hans; T'Sjoen, Guy; Kaufman, Jean-Marc; Vincke, John; Bracke, Piet

2010-01-01

Based on Boyce and Ellis's model on "context" and "biological sensitivity to the context", this article analyzes the interaction between the experience of daily hassles and experimentally induced cardiovascular reactivity as an indicator of stress reactivity, in explaining risk taking and self-esteem. This study found, in a…

Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

PubMed

Ayub, Qaisar; Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

2018-01-01

Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio.

Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments

PubMed Central

Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

2018-01-01

Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio. PMID:29438438

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faizal, Mir, E-mail: f2mir@uwaterloo.ca; Majumder, Barun, E-mail: barunbasanta@iitgn.ac.in

In this paper, we will incorporate the generalized uncertainty principle into field theories with Lifshitz scaling. We will first construct both bosonic and fermionic theories with Lifshitz scaling based on generalized uncertainty principle. After that we will incorporate the generalized uncertainty principle into a non-abelian gauge theory with Lifshitz scaling. We will observe that even though the action for this theory is non-local, it is invariant under local gauge transformations. We will also perform the stochastic quantization of this Lifshitz fermionic theory based generalized uncertainty principle.

Fires in Operating or Abandoned Coal Mines or Heaps of Reactive Materials and the Governing Transport and Reaction Processes

NASA Astrophysics Data System (ADS)

Wuttke, M. W.; Kessels, W.; Wessling, S.; Han, J.

2007-05-01

Spontaneous combustion is a world wide problem for technical operations in mining, waste disposal and power plant facilities. The principle driving the combustion is every where the same independent of the different reactive materials: Fresh air with the common oxygen content is getting in contact with the reactive material by human operations. The following reaction process produces heat at a usually low but constant rate. The reactive material in operating or abandoned coal mines, heaps of coal, waste or reactive minerals is most times strongly broken or fractured, such that the atmospheric oxygen can deeply penetrate into the porous or fractured media. Because the strongly broken or fractured medium with air filled pores and fractures is often combined with a low thermal conductivity of the bulk material the produced heat accumulates and the temperature increases with time. If the reactivity strongly increases with temperature, the temperature rise accelerates up to the "combustion temperature". Once the temperature is high enough the combustion process is determined by the oxygen transport to the combustion center rather than the chemical reactivity. Spontaneous combustion is thus a self- amplifying process where an initial small variation in the parameters and the starting conditions can create exploding combustion hot spots in an apparently homogenous material. The phenomenon will be discussed by various examples in the context of the German - Sino coal fire project. A temperature monitoring in hot fracture systems documents the strong influence of the weather conditions on the combustion process. Numerical calculations show the sensitivity of the combustion to the model geometries, the boundary conditions and mainly the permeability. The most used fire fighting operations like covering and water injection are discussed. A new method of using saltwater for fire fighting is presented and discussed. References: Kessels, W., Wessling, S., Li, X., and Wuttke, M. W. Numerical element distinction for reactive transport modeling regarding reaction rate. In Proceedings of MODFLOW and MORE 2006: Managing Groundwater Systems, May 21 - 24, 2006, Golden, CO USA (2006). Kessels, W., Wuttke, M. W., Wessling, S., and Li, X. Coal fires between self ignition and fire fighting: Numerical modeling and basic geophysical measurements. In ERSEC Ecological Book Series - 4 on Coal Fire Research (2007). Wessling, S., Litschke, T., Wiegand, J., Schlömer, S., and Kessels, W. Simulating dynamic subsurface coal fires and its applications. In ERSEC Ecological Book Series - 4 on Coal Fire Reserach (2007). Wessling, S., Kessels, W., Schmidt, M., and Krause, U. Investigating dynamic underground coal fires by means of numerical simulation. Geophys. J. Int. (submitted).

Reactivation of Latent Tuberculosis: Variations on the Cornell Murine Model

PubMed Central

Scanga, Charles A.; Mohan, V. P.; Joseph, Heather; Yu, Keming; Chan, John; Flynn, JoAnne L.

1999-01-01

Mycobacterium tuberculosis causes active tuberculosis in only a small percentage of infected persons. In most cases, the infection is clinically latent, although immunosuppression can cause reactivation of a latent M. tuberculosis infection. Surprisingly little is known about the biology of the bacterium or the host during latency, and experimental studies on latent tuberculosis suffer from a lack of appropriate animal models. The Cornell model is a historical murine model of latent tuberculosis, in which mice infected with M. tuberculosis are treated with antibiotics (isoniazid and pyrazinamide), resulting in no detectable bacilli by organ culture. Reactivation of infection during this culture-negative state occurred spontaneously and following immunosuppression. In the present study, three variants of the Cornell model were evaluated for their utility in studies of latent and reactivated tuberculosis. The antibiotic regimen, inoculating dose, and antibiotic-free rest period prior to immunosuppression were varied. A variety of immunosuppressive agents, based on immunologic factors known to be important to control of acute infection, were used in attempts to reactivate the infection. Although reactivation of latent infection was observed in all three variants, these models were associated with characteristics that limit their experimental utility, including spontaneous reactivation, difficulties in inducing reactivation, and the generation of altered bacilli. The results from these studies demonstrate that the outcome of Cornell model-based studies depends critically upon the parameters used to establish the model. PMID:10456896

A Novel MS-Cleavable Azo Cross-Linker for Peptide Structure Analysis by Free Radical Initiated Peptide Sequencing (FRIPS)

NASA Astrophysics Data System (ADS)

Iacobucci, Claudio; Hage, Christoph; Schäfer, Mathias; Sinz, Andrea

2017-10-01

The chemical cross-linking/mass spectrometry (MS) approach is a growing research field in structural proteomics that allows gaining insights into protein conformations. It relies on creating distance constraints between cross-linked amino acid side chains that can further be used to derive protein structures. Currently, the most urgent task for designing novel cross-linking principles is an unambiguous and automated assignment of the created cross-linked products. Here, we introduce the homobifunctional, amine-reactive, and water soluble cross-linker azobisimidoester (ABI) as a prototype of a novel class of cross-linkers. The ABI-linker possesses an innovative modular scaffold combining the benefits of collisional activation lability with open shell chemistry. This MS-cleavable cross-linker can be efficiently operated via free radical initiated peptide sequencing (FRIPS) in positive ionization mode. Our proof-of-principle study challenges the gas phase behavior of the ABI-linker for the three amino acids, lysine, leucine, and isoleucine, as well as the model peptide thymopentin. The isomeric amino acids leucine and isoleucine could be discriminated by their characteristic side chain fragments. Collisional activation experiments were conducted via positive electrospray ionization (ESI) on two Orbitrap mass spectrometers. The ABI-mediated formation of odd electron product ions in MS/MS and MS3 experiments was evaluated and compared with a previously described azo-based cross-linker. All cross-linked products were amenable to automated analysis by the MeroX software, underlining the future potential of the ABI-linker for structural proteomics studies. [Figure not available: see fulltext.

Introducing Evidence-Based Principles to Guide Collaborative Approaches to Evaluation: Results of an Empirical Process

ERIC Educational Resources Information Center

Shulha, Lyn M.; Whitmore, Elizabeth; Cousins, J. Bradley; Gilbert, Nathalie; al Hudib, Hind

2016-01-01

This article introduces a set of evidence-based principles to guide evaluation practice in contexts where evaluation knowledge is collaboratively produced by evaluators and stakeholders. The data from this study evolved in four phases: two pilot phases exploring the desirability of developing a set of principles; an online questionnaire survey…

Supporting Teachers in Designing CSCL Activities: A Case Study of Principle-Based Pedagogical Patterns in Networked Second Language Classrooms

ERIC Educational Resources Information Center

Wen, Yun; Looi, Chee-Kit; Chen, Wenli

2012-01-01

This paper proposes the identification and use of principle-based pedagogical patterns to help teachers to translate design principles into actionable teaching activities, and to scaffold student learning with sufficient flexibility and creativity. A set of pedagogical patterns for networked Second language (L2) learning, categorized and…

The Stratigraphic Sandwich. An Inquiry-Based Lesson on Geologic Principles

ERIC Educational Resources Information Center

Hermann, Ronald S.; Miranda, Rommel J.

2013-01-01

This article describes an approach in which students develop and apply definitions prior to their formal introduction to new vocabulary. The example given is an inquiry-based lesson on geologic principles. This approach is illustrated with a lesson that has been used with high school Earth science students on the principles of stratigraphy, though…

Teaching Evidence-Based Practice (EBP) to Speech-Language Therapy Students: Are Students Competent and Confident EBP Users?

ERIC Educational Resources Information Center

Spek, B.; Wieringa-de Waard, M.; Lucas, C.; van Dijk, N.

2013-01-01

Background: The importance and value of the principles of evidence-based practice (EBP) in the decision-making process is recognized by speech-language therapists (SLTs) worldwide and as a result curricula for speech-language therapy students incorporated EBP principles. However, the willingness actually to use EBP principles in their future…

Influence of reactive gas admixture on transition metal cluster nucleation in a gas aggregation cluster source

NASA Astrophysics Data System (ADS)

Peter, Tilo; Polonskyi, Oleksandr; Gojdka, Björn; Mohammad Ahadi, Amir; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

2012-12-01

We quantitatively assessed the influence of reactive gases on the formation processes of transition metal clusters in a gas aggregation cluster source. A cluster source based on a 2 in. magnetron is used to study the production rate of titanium and cobalt clusters. Argon served as working gas for the DC magnetron discharge, and a small amount of reactive gas (oxygen and nitrogen) is added to promote reactive cluster formation. We found that the cluster production rate depends strongly on the reactive gas concentration for very small amounts of reactive gas (less than 0.1% of total working gas), and no cluster formation takes place in the absence of reactive species. The influence of discharge power, reactive gas concentration, and working gas pressure are investigated using a quartz micro balance in a time resolved manner. The strong influence of reactive gas is explained by a more efficient formation of nucleation seeds for metal-oxide or nitride than for pure metal.

PTSD Psychotherapy Outcome Predicted by Brain Activation During Emotional Reactivity and Regulation.

PubMed

Fonzo, Gregory A; Goodkind, Madeleine S; Oathes, Desmond J; Zaiko, Yevgeniya V; Harvey, Meredith; Peng, Kathy K; Weiss, M Elizabeth; Thompson, Allison L; Zack, Sanno E; Lindley, Steven E; Arnow, Bruce A; Jo, Booil; Gross, James J; Rothbaum, Barbara O; Etkin, Amit

2017-12-01

Exposure therapy is an effective treatment for posttraumatic stress disorder (PTSD), but many patients do not respond. Brain functions governing treatment outcome are not well characterized. The authors examined brain systems relevant to emotional reactivity and regulation, constructs that are thought to be central to PTSD and exposure therapy effects, to identify the functional traits of individuals most likely to benefit from treatment. Individuals with PTSD underwent functional MRI (fMRI) while completing three tasks assessing emotional reactivity and regulation. Participants were then randomly assigned to immediate prolonged exposure treatment (N=36) or a waiting list condition (N=30). A random subset of the prolonged exposure group (N=17) underwent single-pulse transcranial magnetic stimulation (TMS) concurrent with fMRI to examine whether predictive activation patterns reflect causal influence within circuits. Linear mixed-effects modeling in line with the intent-to-treat principle was used to examine how baseline brain function moderated the effect of treatment on PTSD symptoms. At baseline, individuals with larger treatment-related symptom reductions (compared with the waiting list condition) demonstrated 1) greater dorsal prefrontal activation and 2) less left amygdala activation, both during emotion reactivity; 3) better inhibition of the left amygdala induced by single TMS pulses to the right dorsolateral prefrontal cortex; and 4) greater ventromedial prefrontal/ventral striatal activation during emotional conflict regulation. Reappraisal-related activation was not a significant moderator of the treatment effect. Capacity to benefit from prolonged exposure in PTSD is gated by the degree to which prefrontal resources are spontaneously engaged when superficially processing threat and adaptively mitigating emotional interference, but not when deliberately reducing negative emotionality.

Rainbows, supernumerary rainbows and interference effects in the angular scattering of chemical reactions: an investigation using Heisenberg's S matrix programme.

PubMed

Shan, Xiao; Xiahou, Chengkui; Connor, J N L

2018-01-03

In earlier research, we have demonstrated that broad "hidden" rainbows can occur in the product differential cross sections (DCSs) of state-to-state chemical reactions. Here we ask the question: can pronounced and localized rainbows, rather than broad hidden ones, occur in reactive DCSs? Further motivation comes from recent measurements by H. Pan and K. Liu, J. Phys. Chem. A, 2016, 120, 6712, of a "bulge" in a reactive DCS, which they conjecture is a rainbow. Our theoretical approach uses a "weak" version of Heisenberg's scattering matrix program (wHSMP) introduced by X. Shan and J. N. L. Connor, Phys. Chem. Chem. Phys., 2011, 13, 8392. This wHSMP uses four general physical principles for chemical reactions to suggest simple parameterized forms for the S matrix; it does not employ a potential energy surface. We use a parameterization in which the modulus of the S matrix is a smooth-step function of the total angular momentum quantum number, J, and (importantly) its phase is a cubic polynomial in J. We demonstrate for a Legendre partial wave series (PWS) the existence of pronounced rainbows, supernumerary rainbows, and other interference effects, in reactive DCSs. We find that reactive rainbows can be more complicated in their structure than the familiar rainbows of elastic scattering. We also analyse the angular scattering using Nearside-Farside (NF) PWS theory and NF PWS Local Angular Momentum (LAM) theory, including resummations of the PWS. In addition, we apply full and NF asymptotic (semiclassical) rainbow theories to the PWS - in particular, the uniform Airy and transitional Airy approximations for the farside scattering. This lets us prove that structure in the DCSs are indeed rainbows, supernumerary rainbows as well as other interference effects.

An architecture for object-oriented intelligent control of power systems in space

NASA Technical Reports Server (NTRS)

Holmquist, Sven G.; Jayaram, Prakash; Jansen, Ben H.

1993-01-01

A control system for autonomous distribution and control of electrical power during space missions is being developed. This system should free the astronauts from localizing faults and reconfiguring loads if problems with the power distribution and generation components occur. The control system uses an object-oriented simulation model of the power system and first principle knowledge to detect, identify, and isolate faults. Each power system component is represented as a separate object with knowledge of its normal behavior. The reasoning process takes place at three different levels of abstraction: the Physical Component Model (PCM) level, the Electrical Equivalent Model (EEM) level, and the Functional System Model (FSM) level, with the PCM the lowest level of abstraction and the FSM the highest. At the EEM level the power system components are reasoned about as their electrical equivalents, e.g, a resistive load is thought of as a resistor. However, at the PCM level detailed knowledge about the component's specific characteristics is taken into account. The FSM level models the system at the subsystem level, a level appropriate for reconfiguration and scheduling. The control system operates in two modes, a reactive and a proactive mode, simultaneously. In the reactive mode the control system receives measurement data from the power system and compares these values with values determined through simulation to detect the existence of a fault. The nature of the fault is then identified through a model-based reasoning process using mainly the EEM. Compound component models are constructed at the EEM level and used in the fault identification process. In the proactive mode the reasoning takes place at the PCM level. Individual components determine their future health status using a physical model and measured historical data. In case changes in the health status seem imminent the component warns the control system about its impending failure. The fault isolation process uses the FSM level for its reasoning base.

14 CFR Sec. 2-1 - Generally accepted accounting principles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Generally accepted accounting principles... AIR CARRIERS General Accounting Provisions Sec. 2-1 Generally accepted accounting principles. (a) The accounting provisions contained in this part are based on generally accepted accounting principles (GAAP...

Exploring participant appreciation of group-based principles for action in community-based physical activity programs for socially vulnerable groups in the Netherlands.

PubMed

Herens, Marion; Wagemakers, Annemarie; Vaandrager, Lenneke; Koelen, Maria

2015-11-25

Physical inactivity is a core risk factor for non-communicable diseases. In the Netherlands, socially vulnerable groups are relatively less active than groups with higher socio-economic status. Community-based health-enhancing physical activity (CBHEPA) programs aim to empower socially vulnerable groups by improving participants' health and wellbeing through physical activity. CBHEPA programs often revolve around group-based principles for action, such as active participation, enjoyment, and fostering group processes. As such principles are rarely made explicit, our study aims to identify which of the group-based principles for action are considered important by participants. Respondents (n = 76) from ten focus groups scored their individual appreciation of group-based principles for action - active participation, enjoyment, and fostering group processes - on a three-point, statement-based scale. Opinions were further discussed in the focus group. Focus group discussions were transcribed and analysed by a team of investigators. The coding procedures, identifying elements appreciated in group-based principles for action, were thematic and data driven. Statements about participatory programming generated much less consensus in appreciation among respondents than statements about enjoyment and fostering group processes. To some extent, group members participated in the development of program content. Participation in group formation or community initiatives was less frequently perceived as something within group members' control. Enjoyment, expressed as physical and emotional experiences, was found to be an individual driver of group exercise. Fostering group processes, expressed as social support, was found to contribute to enjoyment and learning achievements. Responsive leadership, ensuring responsive guidance, by an enthusiastic exercise trainer acting as a role model, were identified as additional necessary principles for action. Group-based principles for action in CBHEPA programs are not clearly demarcated. Fostering group processes is an overarching principle, conditional for the spin-off in terms of enjoyment and active participation. This, in turn, leads to a sense of ownership among participants, who take up responsibility for the exercise group as well as their individual activity behaviour. CBHEPA programs thrive on participants having fun together and exercise trainers' leadership skills. A professional, competent, responsive exercise trainer plays a key role in the organisation and maintenance of CBHEPA programs.

Spindt cold cathode electron gun development program

NASA Technical Reports Server (NTRS)

Spindt, C. A.

1983-01-01

A thin film field emission cathode array and an electron gun based on this emitter array are summarized. Fabricating state of the art cathodes for testing at NASA and NRL, advancing the fabrication technology, developing wedge shaped emitters, and performing emission tests are covered. An anistropic dry etching process (reactive ion beam etching) developed that leads to increasing the packing density of the emitter tips to about 5 x 10 to the 6th power/square cm. Tests with small arrays of emitter tips having about 10 tips has demonstrated current densities of over 100 A/sq cm. Several times using cathodes having a packing density of 1.25 x 10 to the 6th power tips/sq cm. Indications are that the higher packing density achievable with the dry etch process may extend this capability to the 500 A/sq cm range and beyond. The wedge emitter geometry was developed and shown to produce emission. This geometry can (in principle) extend the current density capability of the cathodes beyond the 500 A/sq cm level. An emission microscope was built and tested for use with the cathodes.

Isolation and characterization of lectin from Thai marine crab (Scylla serrata) with binding specificity to sialoglycoconjugates and its application.

PubMed

Kongtawelert, P

1998-12-01

A lectin from Thai marine carb (Scylla serrata) hemolymph has been isolated and purified by affinity column chromatography and preparative electrophoresis. The amino acid composition and 10 amino-terminal residues have been deduced, and its reactivities have been studied using a biotin labeling technique. A method for the determination of sialoglycoconjugates in human serum is described using this lectin. The principle is based on the reaction between the sialoglycoconjugates and biotinylated lectin. The bovine submaxillary mucin (BSM) is immobilized on polystyrene microplate. The unknown sample or sialoglycoconjugate (BSM equivalent) standards, together with excess biotinylated purified lectin (B-lectin), are then added. The B-lectin that binds to the immobilized BSM is then incubated with the peroxidase-conjugated monoclonal antibiotin antibody, and the color that develops after the addition of enzyme substrate is determined by light absorption using a microplate reader. The assay is not only convenient and reliable, but also capable of measuring sialoglycoconjugates in solution at the submicrogram level. It was used in determining the sialoglycoconjugates in human serum from normal subjects and samples positive for carcinoembryonic antigen.

A Heat and Mass Transfer Model of a Silicon Pilot Furnace

NASA Astrophysics Data System (ADS)

Sloman, Benjamin M.; Please, Colin P.; Van Gorder, Robert A.; Valderhaug, Aasgeir M.; Birkeland, Rolf G.; Wegge, Harald

2017-10-01

The most common technological route for metallurgical silicon production is to feed quartz and a carbon source ( e.g., coal, coke, or charcoal) into submerged-arc furnaces, which use electrodes as electrical conductors. We develop a mathematical model of a silicon furnace. A continuum approach is taken, and we derive from first principles the equations governing the time evolution of chemical concentrations, gas partial pressures, velocity, and temperature within a one-dimensional vertical section of a furnace. Numerical simulations are obtained for this model and are shown to compare favorably with experimental results obtained using silicon pilot furnaces. A rising interface is shown to exist at the base of the charge, with motion caused by the heating of the pilot furnace. We find that more reactive carbon reduces the silicon monoxide losses, while reducing the carbon content in the raw material mixture causes greater solid and liquid material to build-up in the charge region, indicative of crust formation (which can be detrimental to the silicon production process). We also comment on how the various findings could be relevant for industrial operations.

Effect of nanoscale flows on the surface structure of nanoporous catalysts.

PubMed

Montemore, Matthew M; Montessori, Andrea; Succi, Sauro; Barroo, Cédric; Falcucci, Giacomo; Bell, David C; Kaxiras, Efthimios

2017-06-07

The surface structure and composition of a multi-component catalyst are critical factors in determining its catalytic performance. The surface composition can depend on the local pressure of the reacting species, leading to the possibility that the flow through a nanoporous catalyst can affect its structure and reactivity. Here, we explore this possibility for oxidation reactions on nanoporous gold, an AgAu bimetallic catalyst. We use microscopy and digital reconstruction to obtain the morphology of a two-dimensional slice of a nanoporous gold sample. Using lattice Boltzmann fluid dynamics simulations along with thermodynamic models based on first-principles total-energy calculations, we show that some sections of this sample have low local O 2 partial pressures when exposed to reaction conditions, which leads to a pure Au surface in these regions, instead of the active bimetallic AgAu phase. We also explore the effect of temperature on the surface structure and find that moderate temperatures (≈300-450 K) should result in the highest intrinsic catalytic performance, in apparent agreement with experimental results.

Core characterization of the new CABRI Water Loop Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritter, G.; Rodiac, F.; Beretz, D.

2011-07-01

The CABRI experimental reactor is located at the Cadarache nuclear research center, southern France. It is operated by the Atomic Energy Commission (CEA) and devoted to IRSN (Institut de Radioprotection et de Surete Nucleaire) safety programmes. It has been successfully operated during the last 30 years, enlightening the knowledge of FBR and LWR fuel behaviour during Reactivity Insertion Accident (RIA) and Loss Of Coolant Accident (LOCA) transients in the frame of IPSN (Institut de Protection et de Surete Nucleaire) and now IRSN programmes devoted to reactor safety. This operation was interrupted in 2003 to allow for a whole facility renewalmore » programme for the need of the CABRI International Programme (CIP) carried out by IRSN under the OECD umbrella. The principle of operation of the facility is based on the control of {sup 3}He, a major gaseous neutron absorber, in the core geometry. The purpose of this paper is to illustrate how several dosimetric devices have been set up to better characterize the core during the upcoming commissioning campaign. It presents the schemes and tools dedicated to core characterization. (authors)« less

A magnetic anti-cancer compound for magnet-guided delivery and magnetic resonance imaging

PubMed Central

Eguchi, Haruki; Umemura, Masanari; Kurotani, Reiko; Fukumura, Hidenobu; Sato, Itaru; Kim, Jeong-Hwan; Hoshino, Yujiro; Lee, Jin; Amemiya, Naoyuki; Sato, Motohiko; Hirata, Kunio; Singh, David J.; Masuda, Takatsugu; Yamamoto, Masahiro; Urano, Tsutomu; Yoshida, Keiichiro; Tanigaki, Katsumi; Yamamoto, Masaki; Sato, Mamoru; Inoue, Seiichi; Aoki, Ichio; Ishikawa, Yoshihiro

2015-01-01

Research on controlled drug delivery for cancer chemotherapy has focused mainly on ways to deliver existing anti-cancer drug compounds to specified targets, e.g., by conjugating them with magnetic particles or encapsulating them in micelles. Here, we show that an iron-salen, i.e., μ-oxo N,N'- bis(salicylidene)ethylenediamine iron (Fe(Salen)), but not other metal salen derivatives, intrinsically exhibits both magnetic character and anti-cancer activity. X-Ray crystallographic analysis and first principles calculations based on the measured structure support this. It promoted apoptosis of various cancer cell lines, likely, via production of reactive oxygen species. In mouse leg tumor and tail melanoma models, Fe(Salen) delivery with magnet caused a robust decrease in tumor size, and the accumulation of Fe(Salen) was visualized by magnetic resonance imaging. Fe(Salen) is an anti-cancer compound with magnetic property, which is suitable for drug delivery and imaging. We believe such magnetic anti-cancer drugs have the potential to greatly advance cancer chemotherapy for new theranostics and drug-delivery strategies. PMID:25779357

Morphology-dependent optical absorption and conduction properties of photoelectrochemical photocatalysts for H2 production: A case study

NASA Astrophysics Data System (ADS)

Huda, Muhammad N.; Turner, John A.

2010-06-01

Efficient photoelectrochemical H2 production by solar irradiation depends not only on the photocatalyst's band gap and its band-edge positions but also on the detailed electronic nature of the bands, such as the localization or delocalization of the band edges and their orbital characteristics. These determine the carrier transport properties, reactivity, light absorption strength, etc. and significantly impact the material's efficiency as a photoconverter. The localization or delocalization of the band edges may arise either due to the orbital nature of the bands or the structural morphology of the material. A recent experimental report on a photocatalyst based on s /p orbitals showed very poor performance for H2 production despite the delocalized nature of the s /p bands as compared to the d-bands of transition metal oxides. It is then important to examine whether this poor performance is inherent to these materials or rather arises from some experimental limitations. A theoretical analysis by first-principle methods is well suited to shed light on this question.

Prediction of warmed-over flavour development in cooked chicken by colorimetric sensor array.

PubMed

Kim, Su-Yeon; Li, Jinglei; Lim, Na-Ri; Kang, Bo-Sik; Park, Hyun-Jin

2016-11-15

The aim of this study was to develop a simple and rapid method based on colorimetric sensor array (CSA) for evaluation of warmed-over flavour (WOF) in cooked chicken. All samples were classified according to storage time by CSA coupled with principle component analysis (PCA) or hierarchical cluster analysis (HCA). The CSA data were used to establish prediction models with thiobarbituric acid reactive substances (TBARS), pentanal, hexanal, or heptanal associated with WOF by partial least square regression (PLSR). For the TBARS model, the coefficient of determination (rp(2)) was 0.9997 in the prediction range of 0.28-0.69mg/kg. In each of the models for pentanal, hexanal, and heptanal, all rp(2) were higher than 0.960 in the range of 0.58-2.10mg/kg, 5.50-11.69mg/kg, and 0.09-0.16mg/kg, respectively. These results demonstrate that the CSA was able to predict WOF development and to distinguish between each storage time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Automated image analysis for quantification of reactive oxygen species in plant leaves.

PubMed

Sekulska-Nalewajko, Joanna; Gocławski, Jarosław; Chojak-Koźniewska, Joanna; Kuźniak, Elżbieta

2016-10-15

The paper presents an image processing method for the quantitative assessment of ROS accumulation areas in leaves stained with DAB or NBT for H 2 O 2 and O 2 - detection, respectively. Three types of images determined by the combination of staining method and background color are considered. The method is based on the principle of supervised machine learning with manually labeled image patterns used for training. The method's algorithm is developed as a JavaScript macro in the public domain Fiji (ImageJ) environment. It allows to select the stained regions of ROS-mediated histochemical reactions, subsequently fractionated according to the weak, medium and intense staining intensity and thus ROS accumulation. It also evaluates total leaf blade area. The precision of ROS accumulation area detection is validated by the Dice Similarity Coefficient in the case of manual patterns. The proposed framework reduces the computation complexity, once prepared, requires less image processing expertise than the competitive methods and represents a routine quantitative imaging assay for a general histochemical image classification. Copyright © 2016 Elsevier Inc. All rights reserved.

Electroencephalographic reactivity testing in unconscious patients: a systematic review of methods and definitions.

PubMed

Admiraal, M M; van Rootselaar, A-F; Horn, J

2017-02-01

Electroencephalographic (EEG) reactivity testing is often presented as a clear-cut element of electrophysiological testing. Absence of EEG reactivity is generally considered an indicator of poor outcome, especially in patients after cardiac arrest. However, guidelines do not clearly describe how to test for reactivity and how to evaluate the results. In a quest for clear guidelines, we performed a systematic review aimed at identifying testing methods and definitions of EEG reactivity. We systematically searched the literature between 1970 and May 2016. Methodological quality of the studies was assessed using the QUality In Prognostic Studies tool. Quality of the descriptions of stimulus protocol and reactivity definition was rated on a four-category grading scale based on reproducibility. We found that protocols for EEG reactivity testing vary greatly and descriptions of protocols are almost never replicable. Furthermore, replicable definitions of presence or absence of EEG reactivity are never provided. In order to draw firm conclusions on EEG reactivity as a prognostic factor, future studies should include a precise stimulation protocol and reactivity definition to facilitate guideline formation. © 2016 EAN.

Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

NASA Astrophysics Data System (ADS)

Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

2018-03-01

The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing

NASA Technical Reports Server (NTRS)

Hewagama, TIlak; Aslam, Shahid; Talabac, Stephen; Allen, John E., Jr.; Annen, John N.; Jennings, Donald E.

2011-01-01

Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed.

Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification.

PubMed

Zeng, Ruijie; Sheng, Hongting; Zhang, Yongcang; Feng, Yan; Chen, Zhi; Wang, Junfeng; Chen, Man; Zhu, Manzhou; Guo, Qingxiang

2014-10-03

A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

Chemical Principls Exemplified

ERIC Educational Resources Information Center

Plumb, Robert C.

1973-01-01

Two topics are discussed: (1) Stomach Upset Caused by Aspirin, illustrating principles of acid-base equilibrium and solubility; (2) Physical Chemistry of the Drinking Duck, illustrating principles of phase equilibria and thermodynamics. (DF)

Design of a Blended Learning Environment Based on Merrill’s Principles

NASA Astrophysics Data System (ADS)

Simarmata, Janner; Djohar, Asari; Purba, Janulis; Juanda, Enjang A.

2018-01-01

Designing blended learning courses requires a systematic approach, in instructional design decisions and implementations, instructional principles help educators not only to specify the elements of the course, but also to provide a solid base from which to build the technology. The blended learning course was designed based on Merrill’s First Principles of Instruction with five phases. This paper helps inform educators about how to develop appropriate learning styles and preferences according to students’ learning needs.

Low HAP Materials

DTIC Science & Technology

2009-09-01

Use maleinized triglycerides to replace UPE • Use novel bio-based reactive diluent to replace styrene Bio-Based Carbon Fibers and Thermosetting Resins...SERDP proposed new start, FY10 • Microbially breakdown lignin into oligomers that can be melt spun and carbonized • Modify renewable...D5045-93 • Designed plant oil-based toughening agents • Uses phase separation to capture MFA reactive diluent • Increases toughness while decreasing

Contributions to Innovative Learning and Teaching? Effective Research-Based Pedagogy--A Response to TLRP's Principles from a European Perspective

ERIC Educational Resources Information Center

Dochy, Filip; Berghmans, Inneke; Kyndt, Eva; Baeten, Marlies

2011-01-01

Starting from the contribution on the "ten principles of effective pedagogy" by James and Pollard, we critically reflect on some of the principles and assess whether these principles can be grounded in the wider European research literature that has accumulated internationally. We conclude that these principles can be supported and…

Lunar Dust Chemical, Electrical, and Mechanical Reactivity: Simulation and Characterization

NASA Technical Reports Server (NTRS)

VanderWal, Randy L.

2008-01-01

Lunar dust is recognized to be a highly reactive material in its native state. Many, if not all Constellation systems will be affected by its adhesion, abrasion, and reactivity. A critical requirement to develop successful strategies for dealing with lunar dust and designing tolerant systems will be to produce similar material for ground-based testing.

Effect of Several New and Currently Available Oxime Cholinesterase Reactivators on Tabun-intoxicated Rats

PubMed Central

Karasova, Jana Zdarova; Kassa, Jiri; Jung, Young-Sik; Musilek, Kamil; Pohanka, Miroslav; Kuca, Kamil

2008-01-01

The therapeutical efficacies of eleven oxime-based acetylcholinesterase reactivators were compared in an in vivo (rat model) study of treatment of intoxication caused by tabun. In this group there were some currently available oximes (obidoxime, trimedoxime and HI-6) and the rest were newly synthesized compounds. The best reactivation efficacy for acetylcholinesterase in blood (expressed as percent of reactivation) among the currently available oximes was observed after administration of trimedoxime (16%) and of the newly synthesized K127 (22432) (25%). The reactivation of butyrylcholinesterase in plasma was also studied; the best reactivators were trimedoxime, K117 (22435), and K127 (22432), with overall reactivation efficacies of approximately 30%. Partial protection of brain ChE against tabun inhibition was observed after administration of trimedoxime (acetylcholinesterase 20%; butyrylcholinesterase 30%) and obidoxime (acetylcholinesterase 12%; butyrylcholinesterase 16%). PMID:19330072

A Novel Physical Sensing Principle for Liquid Characterization Using Paper-Based Hygro-Mechanical Systems (PB-HMS).

PubMed

Perez-Cruz, Angel; Stiharu, Ion; Dominguez-Gonzalez, Aurelio

2017-07-20

In recent years paper-based microfluidic systems have emerged as versatile tools for developing sensors in different areas. In this work; we report a novel physical sensing principle for the characterization of liquids using a paper-based hygro-mechanical system (PB-HMS). The PB-HMS is formed by the interaction of liquid droplets and paper-based mini-structures such as cantilever beams. The proposed principle takes advantage of the hygroscopic properties of paper to produce hygro-mechanical motion. The dynamic response of the PB-HMS reveals information about the tested liquid that can be applied to characterize certain properties of liquids. A suggested method to characterize liquids by means of the proposed principle is introduced. The experimental results show the feasibility of such a method. It is expected that the proposed principle may be applied to sense properties of liquids in different applications where both disposability and portability are of extreme importance.

Further links between the maximum hardness principle and the hard/soft acid/base principle: insights from hard/soft exchange reactions.

PubMed

Chattaraj, Pratim K; Ayers, Paul W; Melin, Junia

2007-08-07

Ayers, Parr, and Pearson recently showed that insight into the hard/soft acid/base (HSAB) principle could be obtained by analyzing the energy of reactions in hard/soft exchange reactions, i.e., reactions in which a soft acid replaces a hard acid or a soft base replaces a hard base [J. Chem. Phys., 2006, 124, 194107]. We show, in accord with the maximum hardness principle, that the hardness increases for favorable hard/soft exchange reactions and decreases when the HSAB principle indicates that hard/soft exchange reactions are unfavorable. This extends the previous work of the authors, which treated only the "double hard/soft exchange" reaction [P. K. Chattaraj and P. W. Ayers, J. Chem. Phys., 2005, 123, 086101]. We also discuss two different approaches to computing the hardness of molecules from the hardness of the composing fragments, and explain how the results differ. In the present context, it seems that the arithmetic mean of fragment softnesses is the preferable definition.

An accurate reactive power control study in virtual flux droop control

NASA Astrophysics Data System (ADS)

Wang, Aimeng; Zhang, Jia

2017-12-01

This paper investigates the problem of reactive power sharing based on virtual flux droop method. Firstly, flux droop control method is derived, where complicated multiple feedback loops and parameter regulation are avoided. Then, the reasons for inaccurate reactive power sharing are theoretically analyzed. Further, a novel reactive power control scheme is proposed which consists of three parts: compensation control, voltage recovery control and flux droop control. Finally, the proposed reactive power control strategy is verified in a simplified microgrid model with two parallel DGs. The simulation results show that the proposed control scheme can achieve accurate reactive power sharing and zero deviation of voltage. Meanwhile, it has some advantages of simple control and excellent dynamic and static performance.

A Learning-Based Approach to Reactive Security

NASA Astrophysics Data System (ADS)

Barth, Adam; Rubinstein, Benjamin I. P.; Sundararajan, Mukund; Mitchell, John C.; Song, Dawn; Bartlett, Peter L.

Despite the conventional wisdom that proactive security is superior to reactive security, we show that reactive security can be competitive with proactive security as long as the reactive defender learns from past attacks instead of myopically overreacting to the last attack. Our game-theoretic model follows common practice in the security literature by making worst-case assumptions about the attacker: we grant the attacker complete knowledge of the defender's strategy and do not require the attacker to act rationally. In this model, we bound the competitive ratio between a reactive defense algorithm (which is inspired by online learning theory) and the best fixed proactive defense. Additionally, we show that, unlike proactive defenses, this reactive strategy is robust to a lack of information about the attacker's incentives and knowledge.

RDoC, DSM, and the reflex physiology of fear: A bio-dimensional analysis of the anxiety disorders spectrum

PubMed Central

Lang, Peter J.; McTeague, Lisa M.; Bradley, Margaret M.

2015-01-01

Evidence is presented supporting a dimension of defensive reactivity that varies across the anxiety disorder spectrum and is defined by physiological responses during threat-imagery challenges that covary with objective measures of psychopathology. Previous imagery studies of anxiety disorders are reviewed, highlighting that, regardless of contemporary diagnostic convention, reliable psychophysiological patterns emerge for patients diagnosed with circumscribed fear compared to those diagnosed with pervasive anxious-misery disorders. Based on the heuristic outlined by the Research Domain Criteria (RDoC) initiative, an exploratory transdiagnostic analysis is presented, based on a sample of 425 treatment-seeking patients from across the spectrum of DSM-IV anxiety diagnoses. Using a composite index of startle reflex and heart rate reactivity during idiographic-fear imagery for each patient, a defensive dimension was defined by ranking patients from most defensively reactive to least reactive and then creating five groups of equivalent size (quintile; N = 85). Subsequent analyses showed significant, parallel trends of diminishing reactivity in both electrodermal and facial EMG reactions across this defensive dimension. Negative affectivity, defined by questionnaire, and extent of functional interference, however, showed consistent, inverse trends with defensive reactivity -- as reports of distress increased, defensive reactivity was increasingly attenuated. Notably, representatives of each principal diagnosis appeared in each quintile, underscoring the reality of pronounced within-diagnosis heterogeneity in defensive reactivity. In concluding, we describe our new RDoC research project, focusing on the assessment of brain circuit function as it determines hypo/hyper reactivity to challenge—somatic and autonomic—and may relate to patients’ stress history and genetic inheritance. PMID:26877123

First-principles study of adsorption-desorption kinetics of aqueous V2+/V3+ redox species on graphite in a vanadium redox flow battery.

PubMed

Jiang, Zhen; Klyukin, Konstantin; Alexandrov, Vitaly

2017-06-14

Vanadium redox flow batteries (VRFBs) represent a promising solution to grid-scale energy storage, and understanding the reactivity of electrode materials is crucial for improving the power density of VRFBs. However, atomistic details about the interactions between vanadium ions and electrode surfaces in aqueous electrolytes are still lacking. Here, we examine the reactivity of the basal (0001) and edge (112[combining macron]0) graphite facets with water and aqueous V 2+ /V 3+ redox species at 300 K employing Car-Parrinello molecular dynamics (CPMD) coupled with metadynamics simulations. The results suggest that the edge surface is characterized by the formation of ketonic C[double bond, length as m-dash]O functional groups due to complete water dissociation into the H/O/H configuration with surface O atoms serving as active sites for adsorption of V 2+ /V 3+ species. The formation of V-O bonds at the surface should significantly improve the kinetics of electron transfer at the edge sites, which is not the case for the basal surface, in agreement with the experimentally hypothesized mechanism.

Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Chao; Dong, Peng; Yi, Jun

The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300–500 °C leads to further B deactivation, while that at 600–800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extendedmore » B{sub 2}I complexes results in further B deactivation in the following CFA at 300–500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600–800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.« less

Dissociation of water and Acetic acid on PbS from first principles

NASA Astrophysics Data System (ADS)

Satta, Alessandra; Ruggerone, Paolo; de Giudici, Giovanni

2008-03-01

The adsorption of complex molecules at mineral surfaces are crucial ingredients for understanding the mechanisms that rule the interaction between minerals and the biosphere and for predicting both the stability and the reactivity of minerals. The present work focuses mainly on the early stages of different adsorption reactions occurring at both the cleavage surface and a high-index vicinal surface of galena (PbS). We have studied the dissociation mechanism of water and acetic acid on the galena surfaces by means of ab initio calculations within the framework of the density functional theory in the generalized gradient approximation and of pseudopotential approach. The calculated adsorption energies of the molecules indicate the stepped surface as the most reactive, as expected. The free energy surface during the reaction process has been explored via metadynamics[1]. The optimized configurations of both reactants and products obtained, were then used to accurately calculate the dissociation energy via the Nudge Elastic Band method[2]. [1] A. Laio and M. Parrinello, PNAS 99, 12562 (2002). [2] G. Mills and H. Jonsson, Phys. Rev. Lett. 72, 1124 (1994).

Antitussive arabinogalactan of Andrographis paniculata demonstrates synergistic effect with andrographolide.

PubMed

Nosáľová, Gabriela; Majee, Sujay Kumar; Ghosh, Kanika; Raja, Washim; Chatterjee, Udipta Ranjan; Jureček, Ludovít; Ray, Bimalendu

2014-08-01

Traditional Indian medicines have been used in humans for thousands of years. While the link to a particular indication has been established in man, the active principle of the formulations often remains unknown. In this study, we aim to investigate the structural features and antitussive activity of fractions from Andrographis paniculata leaves. In vivo investigations of water extract (WE), and both ethanol-soluble (WES) and precipitated (WEP) fractions from WE on the citric-acid induced cough efforts and airways smooth muscle reactivity in guinea pigs were performed. Chemical, chromatographic and spectroscopic analysis revealed the existence of a highly branched pectic arabinogalactan (109kDa) in WEP and andrographolide in WES. WEP showed significant antitussive activity while the potencies of WE and WES are even higher. Neither WE nor WES significantly alter specific airway smooth muscle reactivity. Remarkably, the antitussive activity of arabinogalactan could be increased by synergistic action with andrographolide. Finally, traditional aqueous extraction method provides an arabinogalactan from A. paniculata, which stimulate biological response but without addiction. Copyright © 2014 Elsevier B.V. All rights reserved.

Sleep-Dependent Synaptic Down-Selection (I): Modeling the Benefits of Sleep on Memory Consolidation and Integration

PubMed Central

Nere, Andrew; Hashmi, Atif; Cirelli, Chiara; Tononi, Giulio

2013-01-01

Sleep can favor the consolidation of both procedural and declarative memories, promote gist extraction, help the integration of new with old memories, and desaturate the ability to learn. It is often assumed that such beneficial effects are due to the reactivation of neural circuits in sleep to further strengthen the synapses modified during wake or transfer memories to different parts of the brain. A different possibility is that sleep may benefit memory not by further strengthening synapses, but rather by renormalizing synaptic strength to restore cellular homeostasis after net synaptic potentiation in wake. In this way, the sleep-dependent reactivation of neural circuits could result in the competitive down-selection of synapses that are activated infrequently and fit less well with the overall organization of memories. By using computer simulations, we show here that synaptic down-selection is in principle sufficient to explain the beneficial effects of sleep on the consolidation of procedural and declarative memories, on gist extraction, and on the integration of new with old memories, thereby addressing the plasticity-stability dilemma. PMID:24137153

A directed-overflow and damage-control N -glycosidase in riboflavin biosynthesis

DOE PAGES

Frelin, Océane; Huang, Lili; Hasnain, Ghulam; ...

2015-02-15

Plants and bacteria synthesize the essential human micronutrient riboflavin (vitamin B2) via the same multistep pathway. The early intermediates of this pathway are notoriously reactive, and may be overproduced in vivo because riboflavin biosynthesis enzymes lack feedback controls. Here we demonstrate disposal of riboflavin intermediates by COG3236 (DUF1768), a protein of previously unknown function that is fused to two different riboflavin pathway enzymes in plants and bacteria (RIBR and RibA, respectively). We present cheminformatic, biochemical, genetic, and genomic evidence to show that: (i) plant and bacterial COG3236 proteins cleave the N-glycosidic bond of the first two intermediates of riboflavin biosynthesis,more » yielding relatively innocuous products; (ii) certain COG3236 proteins are in a multienzyme riboflavin biosynthesis complex that gives them privileged access to riboflavin intermediates; and (iii) COG3236 action in Arabidopsis thaliana and Escherichia coli helps maintain flavin levels. We find COG3236 proteins thus illustrate two emerging principles in chemical biology: directed overflow metabolism, in which excess flux is diverted out of a pathway, and the pre-emption of damage from reactive metabolites.« less

Crystalline Structure and Surface Reactivity: Atomistic models are unique tools for dealing with the chemical and physical properties of surfaces.

PubMed

Gatos, H C

1962-08-03

The role of crystalline structure in the surface reactivity of predominantly covalent materials has been examined in terms of chemical bonding concepts. In this context a solid surface can be viewed as a giant lattice defect characterized by dangling bonds. Although it is difficult, at the present stage of development of the quantum mechanical approach to surfaces, to define precisely the perturbations resulting from the abrupt termination of the lattice at the surface, a host of experimental observations can be understood by assuming displacements of surface atoms and distortions of bonding configurations in accordance with simple chemical bonding principles. A purely atomistic approach has been shown to account not only for the chemical behavior but also for certain structural and electrical characteristics of the surfaces considered. A number of phenomena, such as crystal growth and the behavior of certain lattice defects (for example, dislocations), are intimately related to the presence of dangling bonds and the associated distortions of the lattice at the surface (32).

Quantum correlations are tightly bound by the exclusivity principle.

PubMed

Yan, Bin

2013-06-28

It is a fundamental problem in physics of what principle limits the correlations as predicted by our current description of nature, based on quantum mechanics. One possible explanation is the "global exclusivity" principle recently discussed in Phys. Rev. Lett. 110, 060402 (2013). In this work we show that this principle actually has a much stronger restriction on the probability distribution. We provide a tight constraint inequality imposed by this principle and prove that this principle singles out quantum correlations in scenarios represented by any graph. Our result implies that the exclusivity principle might be one of the fundamental principles of nature.

A distributed agent architecture for real-time knowledge-based systems: Real-time expert systems project, phase 1

NASA Technical Reports Server (NTRS)

Lee, S. Daniel

1990-01-01

We propose a distributed agent architecture (DAA) that can support a variety of paradigms based on both traditional real-time computing and artificial intelligence. DAA consists of distributed agents that are classified into two categories: reactive and cognitive. Reactive agents can be implemented directly in Ada to meet hard real-time requirements and be deployed on on-board embedded processors. A traditional real-time computing methodology under consideration is the rate monotonic theory that can guarantee schedulability based on analytical methods. AI techniques under consideration for reactive agents are approximate or anytime reasoning that can be implemented using Bayesian belief networks as in Guardian. Cognitive agents are traditional expert systems that can be implemented in ART-Ada to meet soft real-time requirements. During the initial design of cognitive agents, it is critical to consider the migration path that would allow initial deployment on ground-based workstations with eventual deployment on on-board processors. ART-Ada technology enables this migration while Lisp-based technologies make it difficult if not impossible. In addition to reactive and cognitive agents, a meta-level agent would be needed to coordinate multiple agents and to provide meta-level control.

Unusual thiol-based redox metabolism of parasitic flukes.

PubMed

Tripathi, Timir; Suttiprapa, Sutas; Sripa, Banchob

2017-08-01

Parasitic flukes are exposed to free radicals and, to a greater extent, reactive oxygen species (ROS) during their life cycle. Despite being relentlessly exposed to ROS released by activated immune cells, these parasites can survive for many years in the host. Cellular thiol-based redox metabolism plays a crucial role in parasite survival within their hosts. Evidence shows that oxidative stress and redox homeostasis maintenance are important clinical and pathobiochemical as well as effective therapeutic principles in various diseases. The characterization of redox and antioxidant enzymes is likely to yield good target candidates for novel drugs and vaccines. The absence of active catalase in fluke parasites offers great potential for the development of chemotherapeutic agents that act by perturbing the redox equilibrium of the cell. One of the redox-sensitive enzymes, thioredoxin glutathione reductase (TGR), has been accepted as a drug target against blood fluke infections, and related clinical trials are in progress. TGR is the sole enzyme responsible for Trx and GSH reduction in parasitic flukes. The availability of helminth genomes has accelerated the research on redox metabolism of flukes; however, significant achievements have yet to be attained. The present review summarizes current knowledge on the redox and antioxidant system of the parasitic flukes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Non-uniformly functionalized titanium carbide-based MXenes as an anchoring material for Li-S batteries: A first-principles calculation

NASA Astrophysics Data System (ADS)

Sim, Eun Seob; Chung, Yong-Chae

2018-03-01

In this study, the influence of the non-uniform surface of F- and O-functionalized Ti2C on the anchoring behavior of lithium polysulfide (LiPS) is investigated using density functional theory. In order to consider the non-uniform surface, the substitutional, vacancy, and S-trapped sites of F- and O-functionalized Ti2C are designed. The anchoring behavior is investigated considering the adsorption energy of LiPS, reactivity between Li atoms and the substrate, and the reduction state of the S atoms. On the F-substitutional site of the O-functionalized surface, it is confirmed that the suppressing mechanism changes from the neutralization of S atoms to the anchoring of LiPS. However, too strong of an interaction between Ti atoms exposed at the vacancy site and S atoms induces trapping of the S atom at the vacancies of both F- and O-functionalized surfaces. As a result of the trapping of the S atom, the use of active material decreases. In addition, the S-trapped site originated from the vacancy site does not affect the suppressing mechanism. In conclusion, to optimize the Ti2C-based MXene as an anchoring material for Li-S batteries, the preparation process should be focused on eliminating the vacancy of functional groups.

Development of a point-kinetic verification scheme for nuclear reactor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demazière, C., E-mail: demaz@chalmers.se; Dykin, V.; Jareteg, K.

In this paper, a new method that can be used for checking the proper implementation of time- or frequency-dependent neutron transport models and for verifying their ability to recover some basic reactor physics properties is proposed. This method makes use of the application of a stationary perturbation to the system at a given frequency and extraction of the point-kinetic component of the system response. Even for strongly heterogeneous systems for which an analytical solution does not exist, the point-kinetic component follows, as a function of frequency, a simple analytical form. The comparison between the extracted point-kinetic component and its expectedmore » analytical form provides an opportunity to verify and validate neutron transport solvers. The proposed method is tested on two diffusion-based codes, one working in the time domain and the other working in the frequency domain. As long as the applied perturbation has a non-zero reactivity effect, it is demonstrated that the method can be successfully applied to verify and validate time- or frequency-dependent neutron transport solvers. Although the method is demonstrated in the present paper in a diffusion theory framework, higher order neutron transport methods could be verified based on the same principles.« less

New constraints on Xe incorporation mechanisms in olivine from first-principles calculations

NASA Astrophysics Data System (ADS)

Crépisson, Céline; Blanchard, Marc; Lazzeri, Michele; Balan, Etienne; Sanloup, Chrystèle

2018-02-01

Storage of Xe at depth in silicate minerals has recently been proposed to explain the low Xe abundance in the Earth's and Mars' atmospheres compared to other noble gases (the so-called 'Missing Xenon' issue). Evidences for incorporation, and thus reactivity of Xe in olivine at high pressure and high temperature are based on variations in cell parameters and the appearance of a new Raman band. To constrain the, so far only hypothetical, Xe incorporation mechanism in olivine, we theoretically investigated models of Xe-bearing olivine using density functional theory. Three types of incorporation mechanisms are tested: Xe for Si and Xe for Mg substitutions, and interstitial Xe. Xe for Si substitution, implying an oxidation of Xe, is found to be the only mechanism consistent with experimental observations, leading to an increase of cell parameter a and the appearance of a new Raman band around 720-750 cm-1 associated with Xesbnd O stretching vibrations. Raman spectroscopy makes it possible to identify Xe incorporation site, even at low Xe content, due to high Xe polarizability. An estimation of Xe content in olivine, based on present work and previous in situ experimental results, shows that up to 0.4 at.% Xe could be stored in olivine at depth.

A theoretical study on metal atom-modified BC3 sheets for effects of gas molecule adsorptions

NASA Astrophysics Data System (ADS)

Tang, Yanan; Cui, Xiao; Chen, Weiguang; Zhu, Dalei; Chai, Huaduo; Dai, Xianqi

2018-06-01

Based on the first-principle calculations, the chemical reactivity of transition metal (Fe, Co, Ni, and Cu) dopants within BC3 sheets toward toxic gas molecules (CO, NO, NO2, SO2, and HCN) is comparably investigated. First, the adsorbed gases on metal-modified BC3 sheets exhibit the different stability. Compared with other gases, the metal-modified BC3 substrates exhibit the stronger affinity toward the NO and NO2 molecules (> 1.0 eV), while the adsorbed HCN has the smallest adsorption energy, illustrating that the NO and NO2 as specific toxic gas molecule can be easily detected. Second, the adsorbed gas molecules can effectively regulate the electronic structure and magnetic property of BC3 systems. Fox example, the strong adsorption of NO and NO2 on Fe-modified BC3 systems exhibits non-magnetic property, yet these gases on Co modified BC3 systems exhibit the magnetic character. In addition, the adsorbed NO and SO2 can induce and turn the degree of magnetic moments of Ni- and Cu-modified BC3 systems. Therefore, the different kinds of adsorbed gases on metal-modified BC3 sheets can be distinguished through investigating the changed magnetic moments of system, which would provide important information for designing the functional BC3-based materials.

Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose†

PubMed Central

Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc

2017-01-01

To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen–HPTS (4,4′-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH4) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4–25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H2O2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4′-o-BBV–HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc. PMID:29130464

On the Development of Multi-Step Inverse FEM with Shell Model

NASA Astrophysics Data System (ADS)

Huang, Y.; Du, R.

2005-08-01

The inverse or one-step finite element approach is increasingly used in the sheet metal stamping industry to predict strain distribution and the initial blank shape in the preliminary design stage. Based on the existing theory, there are two types of method: one is based on the principle of virtual work and the other is based on the principle of extreme work. Much research has been conducted to improve the accuracy of simulation results. For example, based on the virtual work principle, Batoz et al. developed a new method using triangular DKT shell elements. In this new method, the bending and unbending effects are considered. Based on the principle of extreme work, Majlessi and et al. proposed the multi-step inverse approach with membrane elements and applied it to an axis-symmetric part. Lee and et al. presented an axis-symmetric shell element model to solve the similar problem. In this paper, a new multi-step inverse method is introduced with no limitation on the workpiece shape. It is a shell element model based on the virtual work principle. The new method is validated by means of comparing to the commercial software system (PAMSTAMP®). The comparison results indicate that the accuracy is good.

Reactive multi-particle collision dynamics with reactive boundary conditions

NASA Astrophysics Data System (ADS)

Sayyidmousavi, Alireza; Rohlf, Katrin

2018-07-01

In the present study, an off-lattice particle-based method called the reactive multi-particle collision (RMPC) dynamics is extended to model reaction-diffusion systems with reactive boundary conditions in which the a priori diffusion coefficient of the particles needs to be maintained throughout the simulation. To this end, the authors have made use of the so-called bath particles whose purpose is only to ensure proper diffusion of the main particles in the system. In order to model partial adsorption by a reactive boundary in the RMPC, the probability of a particle being adsorbed, once it hits the boundary, is calculated by drawing an analogy between the RMPC and Brownian Dynamics. The main advantages of the RMPC compared to other molecular based methods are less computational cost as well as conservation of mass, energy and momentum in the collision and free streaming steps. The proposed approach is tested on three reaction-diffusion systems and very good agreement with the solutions to their corresponding partial differential equations is observed.

Development of Highly Durable and Reactive Regenerable Magnesium-Based Sorbents for CO2 Separation in Coal Gasification Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Javad Abbasian; Armin Hassanzadeh Khayyat; Rachid B. Slimane

The specific objective of this project was to develop physically durable and chemically regenerable MgO-based sorbents that can remove carbon dioxide from raw coal gas at operating condition prevailing in IGCC processes. A total of sixty two (62) different sorbents were prepared in this project. The sorbents were prepared either by various sol-gel techniques (22 formulations) or modification of dolomite (40 formulations). The sorbents were prepared in the form of pellets and in granular forms. The solgel based sorbents had very high physical strength, relatively high surface area, and very low average pore diameter. The magnesium content of the sorbentsmore » was estimated to be 4-6 % w/w. To improve the reactivity of the sorbents toward CO{sub 2}, The sorbents were impregnated with potassium salts. The potassium content of the sorbents was about 5%. The dolomite-based sorbents were prepared by calcination of dolomite at various temperature and calcination environment (CO{sub 2} partial pressure and moisture). Potassium carbonate was added to the half-calcined dolomite through wet impregnation method. The estimated potassium content of the impregnated sorbents was in the range of 1-6% w/w. In general, the modified dolomite sorbents have significantly higher magnesium content, larger pore diameter and lower surface area, resulting in significantly higher reactivity compared to the sol-gel sorbents. The reactivities of a number of sorbents toward CO{sub 2} were determined in a Thermogravimetric Analyzer (TGA) unit. The results indicated that at the low CO{sub 2} partial pressures (i.e., 1 atm), the reactivities of the sorbents toward CO{sub 2} are very low. At elevated pressures (i.e., CO{sub 2} partial pressure of 10 bar) the maximum conversion of MgO obtained with the sol-gel based sorbents was about 5%, which corresponds to a maximum CO{sub 2} absorption capacity of less than 1%. The overall capacity of modified dolomite sorbents were at least one order of magnitude higher than those of the sol-gel based sorbents. The results of the tests conducted with various dolomite-based sorbent indicate that the reactivity of the modified dolomite sorbent increases with increasing potassium concentration, while higher calcination temperature adversely affects the sorbent reactivity. Furthermore, the results indicate that as long as the absorption temperature is well below the equilibrium temperature, the reactivity of the sorbent improves with increasing temperature (350-425 C). As the temperature approaches the equilibrium temperature, because of the significant increase in the rate of reverse (i.e., regeneration) reaction, the rate of CO{sub 2} absorption decreases. The results of cyclic tests show that the reactivity of the sorbent gradually decreases in the cyclic process. To improve long-term durability (i.e., reactivity and capacity) of the sorbent, the sorbent was periodically re-impregnated with potassium additive and calcined. The results indicate that, in general, re-treatment improves the performance of the sorbent, and that, the extent of improvement gradually decreases in the cyclic process. The presence of steam significantly enhances the sorbent reactivity and significantly decreases the rate of decline in sorbent deactivation in the cyclic process.« less

76 FR 49841 - Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-11

.... Each cost allocation method must satisfy six cost allocation principles. DATES: Effective Date: This... 86 c. Commission Determination 99 3. Regional Transmission Planning Principles........ 118 a.... Principles for Regional and Interregional Cost 585 Allocation 1. Use of a Principles-Based Approach 585 a...

4 CFR 2.4 - Merit system principles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 4 Accounts 1 2010-01-01 2010-01-01 false Merit system principles. 2.4 Section 2.4 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM PURPOSE AND GENERAL PROVISION § 2.4 Merit system principles. (a) Merit personnel systems are based on the principle that an organization is best served by...

Best practice principles for community-based obesity prevention: development, content and application.

PubMed

King, L; Gill, T; Allender, S; Swinburn, B

2011-05-01

Best practice in obesity prevention has generally been defined in terms of 'what' needs to be done while neglecting 'how'. A multifaceted definition of best practice, which combines available evidence on what actions to take, with an established process for interpreting this information in a specific community context, provides a more appropriate basis for defining the principles of best practice in community-based obesity prevention. Based on analysis of a range of literature, a preliminary set of principles was drafted and progressively revised through further analyses of published literature and a series of consultations. The framework for best practice principles comprises: community engagement, programme design and planning, evaluation, implementation and sustainability, and governance. Specific principles were formulated within this framework. While many principles were generic, distinctive features of obesity prevention were also covered. The engagement of end-users influenced the design of the formatting of the outputs, which represent three levels of knowledge transfer: detailed evidence summaries, guiding questions for programme planners and a briefer set of questions for simpler communication purposes. The best practice principles provide a valuable mechanism for the translation of existing evidence and experience into the decision-making processes for planning, implementing and evaluating the complex community-based interventions needed for successful obesity prevention. © 2010 The Authors. obesity reviews © 2010 International Association for the Study of Obesity.

Using Multimedia for E-Learning

ERIC Educational Resources Information Center

Mayer, R. E.

2017-01-01

This paper reviews 12 research-based principles for how to design computer-based multimedia instructional materials to promote academic learning, starting with the multimedia principle (yielding a median effect size of d = 1.67 based on five experimental comparisons), which holds that people learn better from computer-based instruction containing…

Implementation of electrochemical, optical and denuder-based sensors and sampling techniques on UAV for volcanic gas measurements: examples from Masaya, Turrialba and Stromboli volcanoes

NASA Astrophysics Data System (ADS)

Rüdiger, Julian; Tirpitz, Jan-Lukas; Maarten de Moor, J.; Bobrowski, Nicole; Gutmann, Alexandra; Liuzzo, Marco; Ibarra, Martha; Hoffmann, Thorsten

2018-04-01

Volcanoes are a natural source of several reactive gases (e.g., sulfur and halogen containing species) and nonreactive gases (e.g., carbon dioxide) to the atmosphere. The relative abundance of carbon and sulfur in volcanic gas as well as the total sulfur dioxide emission rate from a volcanic vent are established parameters in current volcano-monitoring strategies, and they oftentimes allow insights into subsurface processes. However, chemical reactions involving halogens are thought to have local to regional impact on the atmospheric chemistry around passively degassing volcanoes. In this study we demonstrate the successful deployment of a multirotor UAV (quadcopter) system with custom-made lightweight payloads for the compositional analysis and gas flux estimation of volcanic plumes. The various applications and their potential are presented and discussed in example studies at three volcanoes encompassing flight heights of 450 to 3300 m and various states of volcanic activity. Field applications were performed at Stromboli volcano (Italy), Turrialba volcano (Costa Rica) and Masaya volcano (Nicaragua). Two in situ gas-measuring systems adapted for autonomous airborne measurements, based on electrochemical and optical detection principles, as well as an airborne sampling unit, are introduced. We show volcanic gas composition results including abundances of CO2, SO2 and halogen species. The new instrumental setups were compared with established instruments during ground-based measurements at Masaya volcano, which resulted in CO2 / SO2 ratios of 3.6 ± 0.4. For total SO2 flux estimations a small differential optical absorption spectroscopy (DOAS) system measured SO2 column amounts on transversal flights below the plume at Turrialba volcano, giving 1776 ± 1108 T d-1 and 1616 ± 1007 T d-1 of SO2 during two traverses. At Stromboli volcano, elevated CO2 / SO2 ratios were observed at spatial and temporal proximity to explosions by airborne in situ measurements. Reactive bromine to sulfur ratios of 0.19 × 10-4 to 9.8 × 10-4 were measured in situ in the plume of Stromboli volcano, downwind of the vent.

Emotional facial recognition in proactive and reactive violent offenders.

PubMed

Philipp-Wiegmann, Florence; Rösler, Michael; Retz-Junginger, Petra; Retz, Wolfgang

2017-10-01

The purpose of this study is to analyse individual differences in the ability of emotional facial recognition in violent offenders, who were characterised as either reactive or proactive in relation to their offending. In accordance with findings of our previous study, we expected higher impairments in facial recognition in reactive than proactive violent offenders. To assess the ability to recognize facial expressions, the computer-based Facial Emotional Expression Labeling Test (FEEL) was performed. Group allocation of reactive und proactive violent offenders and assessment of psychopathic traits were performed by an independent forensic expert using rating scales (PROREA, PCL-SV). Compared to proactive violent offenders and controls, the performance of emotion recognition in the reactive offender group was significantly lower, both in total and especially in recognition of negative emotions such as anxiety (d = -1.29), sadness (d = -1.54), and disgust (d = -1.11). Furthermore, reactive violent offenders showed a tendency to interpret non-anger emotions as anger. In contrast, proactive violent offenders performed as well as controls. General and specific deficits in reactive violent offenders are in line with the results of our previous study and correspond to predictions of the Integrated Emotion System (IES, 7) and the hostile attribution processes (21). Due to the different error pattern in the FEEL test, the theoretical distinction between proactive and reactive aggression can be supported based on emotion recognition, even though aggression itself is always a heterogeneous act rather than a distinct one-dimensional concept.

Elevated and cross‐responsive CD1a‐reactive T cells in bee and wasp venom allergic individuals

PubMed Central

Subramaniam, Sumithra; Aslam, Aamir; Misbah, Siraj A.; Salio, Mariolina; Cerundolo, Vincenzo; Moody, D Branch

2015-01-01

The role of CD1a‐reactive T cells in human allergic disease is unknown. We have previously shown that circulating CD1a‐reactive T cells recognize neolipid antigens generated by bee and wasp venom phospholipase, and here tested the hypothesis that venom‐responsive CD1a‐reactive T cells associate with venom allergy. Circulating T cells from bee and wasp venom allergic individuals, before and during immunotherapy, were exposed to CD1a‐transfected K562 cells in the presence of wasp or bee venom. T‐cell response was evaluated based on IFNγ, GM‐CSF, and IL‐13 cytokine production. Venom allergic individuals showed significantly higher frequencies of IFN‐γ, GM‐CSF, and IL‐13 producing CD1a‐reactive T cells responsive to venom and venom‐derived phospholipase than healthy individuals. Venom‐responsive CD1a‐reactive T cells were cross‐responsive between wasp and bee suggesting shared pathways of allergenicity. Frequencies of CD1a‐reactive T cells were initially induced during subcutaneous immunotherapy, peaking by weeks 5, but then reduced despite escalation of antigen dose. Our current understanding of venom allergy and immunotherapy is largely based on peptide and protein‐specific T cell and antibody responses. Here, we show that lipid antigens and CD1a‐reactive T cells associate with the allergic response. These data have implications for mechanisms of allergy and approaches to immunotherapy. PMID:26518614

Valence atom with bohmian quantum potential: the golden ratio approach

PubMed Central

2012-01-01

Background The alternative quantum mechanical description of total energy given by Bohmian theory was merged with the concept of the golden ratio and its appearance as the Heisenberg imbalance to provide a new density-based description of the valence atomic state and reactivity charge with the aim of clarifying their features with respect to the so-called DFT ground state and critical charge, respectively. Results The results, based on the so-called double variational algorithm for chemical spaces of reactivity, are fundamental and, among other issues regarding chemical bonding, solve the existing paradox of using a cubic parabola to describe a quadratic charge dependency. Conclusions Overall, the paper provides a qualitative-quantitative explanation of chemical reactivity based on more than half of an electronic pair in bonding, and provide new, more realistic values for the so-called “universal” electronegativity and chemical hardness of atomic systems engaged in reactivity (analogous to the atoms-in-molecules framework). PMID:23146157

Nanosized iron based permeable reactive barriers for nitrate removal - Systematic review

NASA Astrophysics Data System (ADS)

Araújo, Rui; Castro, Ana C. Meira; Santos Baptista, João; Fiúza, António

2016-08-01

It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focussing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in this review. This study's outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.

Synthetic peptides and fluorogenic substrates related to the reactive site sequence of Kunitz-type inhibitors isolated from Bauhinia: interaction with human plasma kallikrein.

PubMed

Oliva, M L; Santomauro-Vaz, E M; Andrade, S A; Juliano, M A; Pott, V J; Sampaio, M U; Sampaio, C A

2001-01-01

We have previously described Kunitz-type serine proteinase inhibitors purified from Bauhinia seeds. Human plasma kallikrein shows different susceptibility to those inhibitors. In this communication, we describe the interaction of human plasma kallikrein with fluorogenic and non-fluorogenic peptides based on the Bauhinia inhibitors' reactive site. The hydrolysis of the substrate based on the B. variegata inhibitor reactive site sequence, Abz-VVISALPRSVFIQ-EDDnp (Km 1.42 microM, kcat 0.06 s(-1), and kcat/Km 4.23 x 10(4) M(-1) s(-1)), is more favorable than that of Abz-VMIAALPRTMFIQ-EDDnp, related to the B. ungulata sequence (Km 0.43 microM, kcat 0.00017 s(-1), and kcat/Km 3.9 x 10(2) M(-1) s(-1)). Human plasma kallikrein does not hydrolyze the substrates Abz-RPGLPVRFESPL-EDDnp and Abz-FESPLRINIIKE-EDDnp based on the B. bauhinioides inhibitor reactive site sequence, the most effective inhibitor of the enzyme. These peptides are competitive inhibitors with Ki values in the nM range. The synthetic peptide containing 19 amino acids based on the B. bauhinioides inhibitor reactive site (RPGLPVRFESPL) is poorly cleaved by kallikrein. The given substrates are highly specific for trypsin and chymotrypsin hydrolysis. Other serine proteinases such as factor Xa, factor XII, thrombin and plasmin do not hydrolyze B. bauhinioides inhibitor related substrates.

Interpreting T-Cell Cross-reactivity through Structure: Implications for TCR-Based Cancer Immunotherapy.

PubMed

Antunes, Dinler A; Rigo, Maurício M; Freitas, Martiela V; Mendes, Marcus F A; Sinigaglia, Marialva; Lizée, Gregory; Kavraki, Lydia E; Selin, Liisa K; Cornberg, Markus; Vieira, Gustavo F

2017-01-01

Immunotherapy has become one of the most promising avenues for cancer treatment, making use of the patient's own immune system to eliminate cancer cells. Clinical trials with T-cell-based immunotherapies have shown dramatic tumor regressions, being effective in multiple cancer types and for many different patients. Unfortunately, this progress was tempered by reports of serious (even fatal) side effects. Such therapies rely on the use of cytotoxic T-cell lymphocytes, an essential part of the adaptive immune system. Cytotoxic T-cells are regularly involved in surveillance and are capable of both eliminating diseased cells and generating protective immunological memory. The specificity of a given T-cell is determined through the structural interaction between the T-cell receptor (TCR) and a peptide-loaded major histocompatibility complex (MHC); i.e., an intracellular peptide-ligand displayed at the cell surface by an MHC molecule. However, a given TCR can recognize different peptide-MHC (pMHC) complexes, which can sometimes trigger an unwanted response that is referred to as T-cell cross-reactivity. This has become a major safety issue in TCR-based immunotherapies, following reports of melanoma-specific T-cells causing cytotoxic damage to healthy tissues (e.g., heart and nervous system). T-cell cross-reactivity has been extensively studied in the context of viral immunology and tissue transplantation. Growing evidence suggests that it is largely driven by structural similarities of seemingly unrelated pMHC complexes. Here, we review recent reports about the existence of pMHC "hot-spots" for cross-reactivity and propose the existence of a TCR interaction profile (i.e., a refinement of a more general TCR footprint in which some amino acid residues are more important than others in triggering T-cell cross-reactivity). We also make use of available structural data and pMHC models to interpret previously reported cross-reactivity patterns among virus-derived peptides. Our study provides further evidence that structural analyses of pMHC complexes can be used to assess the intrinsic likelihood of cross-reactivity among peptide-targets. Furthermore, we hypothesize that some apparent inconsistencies in reported cross-reactivities, such as a preferential directionality, might also be driven by particular structural features of the targeted pMHC complex. Finally, we explain why TCR-based immunotherapy provides a special context in which meaningful T-cell cross-reactivity predictions can be made.

Interpreting T-Cell Cross-reactivity through Structure: Implications for TCR-Based Cancer Immunotherapy

PubMed Central

Antunes, Dinler A.; Rigo, Maurício M.; Freitas, Martiela V.; Mendes, Marcus F. A.; Sinigaglia, Marialva; Lizée, Gregory; Kavraki, Lydia E.; Selin, Liisa K.; Cornberg, Markus; Vieira, Gustavo F.

2017-01-01

Immunotherapy has become one of the most promising avenues for cancer treatment, making use of the patient’s own immune system to eliminate cancer cells. Clinical trials with T-cell-based immunotherapies have shown dramatic tumor regressions, being effective in multiple cancer types and for many different patients. Unfortunately, this progress was tempered by reports of serious (even fatal) side effects. Such therapies rely on the use of cytotoxic T-cell lymphocytes, an essential part of the adaptive immune system. Cytotoxic T-cells are regularly involved in surveillance and are capable of both eliminating diseased cells and generating protective immunological memory. The specificity of a given T-cell is determined through the structural interaction between the T-cell receptor (TCR) and a peptide-loaded major histocompatibility complex (MHC); i.e., an intracellular peptide–ligand displayed at the cell surface by an MHC molecule. However, a given TCR can recognize different peptide–MHC (pMHC) complexes, which can sometimes trigger an unwanted response that is referred to as T-cell cross-reactivity. This has become a major safety issue in TCR-based immunotherapies, following reports of melanoma-specific T-cells causing cytotoxic damage to healthy tissues (e.g., heart and nervous system). T-cell cross-reactivity has been extensively studied in the context of viral immunology and tissue transplantation. Growing evidence suggests that it is largely driven by structural similarities of seemingly unrelated pMHC complexes. Here, we review recent reports about the existence of pMHC “hot-spots” for cross-reactivity and propose the existence of a TCR interaction profile (i.e., a refinement of a more general TCR footprint in which some amino acid residues are more important than others in triggering T-cell cross-reactivity). We also make use of available structural data and pMHC models to interpret previously reported cross-reactivity patterns among virus-derived peptides. Our study provides further evidence that structural analyses of pMHC complexes can be used to assess the intrinsic likelihood of cross-reactivity among peptide-targets. Furthermore, we hypothesize that some apparent inconsistencies in reported cross-reactivities, such as a preferential directionality, might also be driven by particular structural features of the targeted pMHC complex. Finally, we explain why TCR-based immunotherapy provides a special context in which meaningful T-cell cross-reactivity predictions can be made. PMID:29046675

C-reactive protein levels and treatment resistance in schizophrenia-A Danish population-based cohort study.

PubMed

Horsdal, Henriette Thisted; Wimberley, Theresa; Benros, Michael Eriksen; Gasse, Christiane

2017-11-01

Schizophrenia is associated with increased levels of inflammatory markers. However, it remains unclear whether inflammatory markers are associated with treatment-resistant schizophrenia. We conducted a population-based follow-up study among individuals with a first-time schizophrenia diagnosis and a baseline C-reactive protein measurement (a commonly available marker of systemic inflammation) from 2000 to 2012. We defined treatment resistance as the earliest observed instance of either clozapine initiation or hospital admission due to schizophrenia after having received at least 2 prior antipsychotic monotherapy trials of adequate duration. We used adjusted Cox regression analysis to calculate hazard ratios. We identified 390 individuals with a C-reactive protein measurement at first-time schizophrenia diagnosis. A nonsignificant higher median C-reactive protein (4.0 vs. 3.1 mg/L, p = .13) was observed among the 52 (13.3%) treatment-resistant individuals. Increased levels of C-reactive protein (above 3 mg/L) at baseline were not associated with treatment resistance (adjusted hazard ratio = 0.99, 95% confidence interval [0.56, 1.73]). C-reactive protein, as a single inflammatory marker, appears insufficient to detect treatment-resistant schizophrenia. Copyright © 2017 John Wiley & Sons, Ltd.

Exposure-time based modeling of nonlinear reactive transport in porous media subject to physical and geochemical heterogeneity.

PubMed

Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T; Finkel, Michael; Blowes, David W; Cirpka, Olaf A

2016-09-01

Transport of reactive solutes in groundwater is affected by physical and chemical heterogeneity of the porous medium, leading to complex spatio-temporal patterns of concentrations and reaction rates. For certain cases of bioreactive transport, it could be shown that the concentrations of reactive constituents in multi-dimensional domains are approximately aligned with isochrones, that is, lines of identical travel time, provided that the chemical properties of the matrix are uniform. We extend this concept to combined physical and chemical heterogeneity by additionally considering the time that a water parcel has been exposed to reactive materials, the so-called exposure time. We simulate bioreactive transport in a one-dimensional domain as function of time and exposure time, rather than space. Subsequently, we map the concentrations to multi-dimensional heterogeneous domains by means of the mean exposure time at each location in the multi-dimensional domain. Differences in travel and exposure time at a given location are accounted for as time difference. This approximation simplifies reactive-transport simulations significantly under conditions of steady-state flow when reactions are restricted to specific locations. It is not expected to be exact in realistic applications because the underlying assumption, such as neglecting transverse mixing altogether, may not hold. We quantify the error introduced by the approximation for the hypothetical case of a two-dimensional, binary aquifer made of highly-permeable, non-reactive and low-permeable, reactive materials releasing dissolved organic matter acting as electron donor for aerobic respiration and denitrification. The kinetically controlled reactions are catalyzed by two non-competitive bacteria populations, enabling microbial growth. Even though the initial biomass concentrations were uniform, the interplay between transport, non-uniform electron-donor supply, and bio-reactions led to distinct spatial patterns of the two types of biomass at late times. Results obtained by mapping the exposure-time based results to the two-dimensional domain are compared with simulations based on the two-dimensional, spatially explicit advection-dispersion-reaction equation. Once quasi-steady state has been reached, we find a good agreement in terms of the chemical-compound concentrations between the two approaches inside the reactive zones, whereas the exposure-time based model is not able to capture reactions occurring in the zones with zero electron-donor release. We conclude that exposure-time models provide good approximations of nonlinear bio-reactive transport when transverse mixing is not the overall controlling process and all reactions are essentially restricted to distinct reactive zones. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of the Hard and Soft, Acids and Bases (HSAB) theory to toxicant--target interactions.

PubMed

Lopachin, Richard M; Gavin, Terrence; Decaprio, Anthony; Barber, David S

2012-02-20

Many chemical toxicants and/or their active metabolites are electrophiles that cause cell injury by forming covalent bonds with nucleophilic targets on biological macromolecules. Covalent reactions between nucleophilic and electrophilic reagents are, however, discriminatory since there is a significant degree of selectivity associated with these interactions. Over the course of the past few decades, the theory of Hard and Soft, Acids and Bases (HSAB) has proven to be a useful tool in predicting the outcome of such reactions. This concept utilizes the inherent electronic characteristic of polarizability to define, for example, reacting electrophiles and nucleophiles as either hard or soft. These HSAB definitions have been successfully applied to chemical-induced toxicity in biological systems. Thus, according to this principle, a toxic electrophile reacts preferentially with biological targets of similar hardness or softness. The soft/hard classification of a xenobiotic electrophile has obvious utility in discerning plausible biological targets and molecular mechanisms of toxicity. The purpose of this perspective is to discuss the HSAB theory of electrophiles and nucleophiles within a toxicological framework. In principle, covalent bond formation can be described by using the properties of their outermost or frontier orbitals. Because these orbital energies for most chemicals can be calculated using quantum mechanical models, it is possible to quantify the relative softness (σ) or hardness (η) of electrophiles or nucleophiles and to subsequently convert this information into useful indices of reactivity. This atomic level information can provide insight into the design of corroborative laboratory research and thereby help investigators discern corresponding molecular sites and mechanisms of toxicant action. The use of HSAB parameters has also been instrumental in the development and identification of potential nucleophilic cytoprotectants that can scavenge toxic electrophiles. Clearly, the difficult task of delineating molecular sites and mechanisms of toxicant action can be facilitated by the application of this quantitative approach.

APPLICATION OF THE HARD AND SOFT, ACIDS AND BASES (HSAB) THEORY TO TOXICANT-TARGET INTERACTIONS

PubMed Central

LoPachin, Richard M.; Gavin, Terrence; DeCaprio, Anthony; Barber, David S.

2011-01-01

Many chemical toxicants and/or their active metabolites are electrophiles that cause cell injury by forming covalent bonds with nucleophilic targets on biological macromolecules. Covalent reactions between nucleophilic and electrophilic reagents are however discriminatory, since there is a significant degree of selectivity associated with these interactions. Over the course of the past few decades, the theory of Hard and Soft, Acid and Bases (HSAB) has proven to be a useful tool in predicting the outcome of such reactions. This concept utilizes the inherent electronic characteristic of polarizability to define, for example, reacting electrophiles and nucleophiles as either hard or soft. These HSAB definitions have been successfully applied to chemical-induced toxicity in biological systems. Thus, according to this principle, a toxic electrophile reacts preferentially with biological targets of similar hardness or softness. The soft/hard classification of a xenobiotic electrophile has obvious utility in discerning plausible biological targets and molecular mechanisms of toxicity. The purpose of this Perspective is to discuss the HSAB theory of electrophiles and nucleophiles within a toxicological framework. In principle, covalent bond formation can be described by using the properties of their outermost or frontier orbitals. Because these orbital energies for most chemicals can be calculated using quantum mechanical models, it is possible to quantify the relative softness (σ) or hardness (η) of electrophiles or nucleophiles and to subsequently convert this information into useful indices of reactivity. This atomic level information can provide insight into the design of corroborative laboratory research and thereby help investigators discern corresponding molecular sites and mechanisms of toxicant action. The use of HSAB parameters has also been instrumental in the development and identification of potential nucleophilic cytoprotectants that can scavenge toxic electrophiles. Clearly, the difficult task of delineating molecular sites and mechanisms of toxicant action can be facilitated by the application of this quantitative approach. PMID:22053936

Dispositional Mindfulness Uncouples Physiological and Emotional Reactivity to a Laboratory Stressor and Emotional Reactivity to Executive Functioning Lapses in Daily Life

PubMed Central

Feldman, Greg; Lavalle, Jayne; Gildawie, Kelsea; Greeson, Jeffrey M.

2016-01-01

Both dispositional mindfulness and mindfulness training may help to uncouple the degree to which distress is experienced in response to aversive internal experience and external events. Because emotional reactivity is a transdiagnostic process implicated in numerous psychological disorders, dispositional mindfulness and mindfulness training could exert mental health benefits, in part, by buffering emotional reactivity. The present studies examine whether dispositional mindfulness moderates two understudied processes in stress reactivity research: the degree of concordance between subjective and physiological reactivity to a laboratory stressor (Study 1); and the degree of dysphoric mood reactivity to lapses in executive functioning in daily life (Study 2). In both studies, lower emotional reactivity to aversive experiences was observed among individuals scoring higher in mindfulness, particularly non-judging, relative to those scoring lower in mindfulness. These findings support the hypothesis that higher dispositional mindfulness fosters lower emotional reactivity. Results are discussed in terms of implications for applying mindfulness-based interventions to a range of psychological disorders in which people have difficulty regulating emotional reactions to stress. PMID:27087863

Dispositional Mindfulness Uncouples Physiological and Emotional Reactivity to a Laboratory Stressor and Emotional Reactivity to Executive Functioning Lapses in Daily Life.

PubMed

Feldman, Greg; Lavalle, Jayne; Gildawie, Kelsea; Greeson, Jeffrey M

2016-04-01

Both dispositional mindfulness and mindfulness training may help to uncouple the degree to which distress is experienced in response to aversive internal experience and external events. Because emotional reactivity is a transdiagnostic process implicated in numerous psychological disorders, dispositional mindfulness and mindfulness training could exert mental health benefits, in part, by buffering emotional reactivity. The present studies examine whether dispositional mindfulness moderates two understudied processes in stress reactivity research: the degree of concordance between subjective and physiological reactivity to a laboratory stressor (Study 1); and the degree of dysphoric mood reactivity to lapses in executive functioning in daily life (Study 2). In both studies, lower emotional reactivity to aversive experiences was observed among individuals scoring higher in mindfulness, particularly non-judging, relative to those scoring lower in mindfulness. These findings support the hypothesis that higher dispositional mindfulness fosters lower emotional reactivity. Results are discussed in terms of implications for applying mindfulness-based interventions to a range of psychological disorders in which people have difficulty regulating emotional reactions to stress.

Principles of liquids working in heat engines

PubMed Central

Allen, P. C.; Knight, W. R.; Paulson, D. N.; Wheatley, J. C.

1980-01-01

The thermodynamic and thermophysical properties of liquids suggest that they should be powerful working fluids in heat engines. Their use requires heat engines based conceptually on the Stirling and Malone principles. The principles are explained, and then experiments on propylene are presented that demonstrate the principles and confirm the thermodynamic analysis. PMID:16592756

A solution to the biodiversity paradox by logical deterministic cellular automata.

PubMed

Kalmykov, Lev V; Kalmykov, Vyacheslav L

2015-06-01

The paradox of biological diversity is the key problem of theoretical ecology. The paradox consists in the contradiction between the competitive exclusion principle and the observed biodiversity. The principle is important as the basis for ecological theory. On a relatively simple model we show a mechanism of indefinite coexistence of complete competitors which violates the known formulations of the competitive exclusion principle. This mechanism is based on timely recovery of limiting resources and their spatio-temporal allocation between competitors. Because of limitations of the black-box modeling there was a problem to formulate the exclusion principle correctly. Our white-box multiscale model of two-species competition is based on logical deterministic individual-based cellular automata. This approach provides an automatic deductive inference on the basis of a system of axioms, and gives a direct insight into mechanisms of the studied system. It is one of the most promising methods of artificial intelligence. We reformulate and generalize the competitive exclusion principle and explain why this formulation provides a solution of the biodiversity paradox. In addition, we propose a principle of competitive coexistence.

Comparison of massage based on the tensegrity principle and classic massage in treating chronic shoulder pain.

PubMed

Kassolik, Krzysztof; Andrzejewski, Waldemar; Brzozowski, Marcin; Wilk, Iwona; Górecka-Midura, Lucyna; Ostrowska, Bożena; Krzyżanowski, Dominik; Kurpas, Donata

2013-09-01

The purpose of this study was to compare the clinical outcomes of classic massage to massage based on the tensegrity principle for patients with chronic idiopathic shoulder pain. Thirty subjects with chronic shoulder pain symptoms were divided into 2 groups, 15 subjects received classic (Swedish) massage to tissues surrounding the glenohumeral joint and 15 subjects received the massage using techniques based on the tensegrity principle. The tensegrity principle is based on directing treatment to the painful area and the tissues (muscles, fascia, and ligaments) that structurally support the painful area, thus treating tissues that have direct and indirect influence on the motion segment. Both treatment groups received 10 sessions over 2 weeks, each session lasted 20 minutes. The McGill Pain Questionnaire and glenohumeral ranges of motion were measured immediately before the first massage session, on the day the therapy ended 2 weeks after therapy started, and 1 month after the last massage. Subjects receiving massage based on the tensegrity principle demonstrated statistically significance improvement in the passive and active ranges of flexion and abduction of the glenohumeral joint. Pain decreased in both massage groups. This study showed increases in passive and active ranges of motion for flexion and abduction in patients who had massage based on the tensegrity principle. For pain outcomes, both classic and tensegrity massage groups demonstrated improvement. Copyright © 2013 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Quantification of EEG reactivity in comatose patients

PubMed Central

Hermans, Mathilde C.; Westover, M. Brandon; van Putten, Michel J.A.M.; Hirsch, Lawrence J.; Gaspard, Nicolas

2016-01-01

Objective EEG reactivity is an important predictor of outcome in comatose patients. However, visual analysis of reactivity is prone to subjectivity and may benefit from quantitative approaches. Methods In EEG segments recorded during reactivity testing in 59 comatose patients, 13 quantitative EEG parameters were used to compare the spectral characteristics of 1-minute segments before and after the onset of stimulation (spectral temporal symmetry). Reactivity was quantified with probability values estimated using combinations of these parameters. The accuracy of probability values as a reactivity classifier was evaluated against the consensus assessment of three expert clinical electroencephalographers using visual analysis. Results The binary classifier assessing spectral temporal symmetry in four frequency bands (delta, theta, alpha and beta) showed best accuracy (Median AUC: 0.95) and was accompanied by substantial agreement with the individual opinion of experts (Gwet’s AC1: 65–70%), at least as good as inter-expert agreement (AC1: 55%). Probability values also reflected the degree of reactivity, as measured by the inter-experts’ agreement regarding reactivity for each individual case. Conclusion Automated quantitative EEG approaches based on probabilistic description of spectral temporal symmetry reliably quantify EEG reactivity. Significance Quantitative EEG may be useful for evaluating reactivity in comatose patients, offering increased objectivity. PMID:26183757

Measuring Memory Reactivation With Functional MRI: Implications for Psychological Theory.

PubMed

Levy, Benjamin J; Wagner, Anthony D

2013-01-01

Environmental cues often remind us of earlier experiences by triggering the reactivation of memories of events past. Recent evidence suggests that memory reactivation can be observed using functional MRI and that distributed pattern analyses can even provide evidence of reactivation on individual trials. The ability to measure memory reactivation offers unique and powerful leverage on theoretical issues of long-standing interest in cognitive psychology, providing a means to address questions that have proven difficult to answer with behavioral data alone. In this article, we consider three instances. First, reactivation measures can indicate whether memory-based inferences (i.e., generalization) arise through the encoding of integrated cross-event representations or through the flexible expression of separable event memories. Second, online measures of memory reactivation may inform theories of forgetting by providing information about when competing memories are reactivated during competitive retrieval situations. Finally, neural reactivation may provide a window onto the role of replay in memory consolidation. The ability to track memory reactivation, including at the individual trial level, provides unique leverage that is not afforded by behavioral measures and thus promises to shed light on such varied topics as generalization, integration, forgetting, and consolidation. © The Author(s) 2013.

Principles of cooperation across systems: from human sharing to multicellularity and cancer.

PubMed

Aktipis, Athena

2016-01-01

From cells to societies, several general principles arise again and again that facilitate cooperation and suppress conflict. In this study, I describe three general principles of cooperation and how they operate across systems including human sharing, cooperation in animal and insect societies and the massively large-scale cooperation that occurs in our multicellular bodies. The first principle is that of Walk Away: that cooperation is enhanced when individuals can leave uncooperative partners. The second principle is that resource sharing is often based on the need of the recipient (i.e., need-based transfers) rather than on strict account-keeping. And the last principle is that effective scaling up of cooperation requires increasingly sophisticated and costly cheater suppression mechanisms. By comparing how these principles operate across systems, we can better understand the constraints on cooperation. This can facilitate the discovery of novel ways to enhance cooperation and suppress cheating in its many forms, from social exploitation to cancer.

Reaction Mechanism of Covalent Modification of Phosphatidylethanolamine Lipids by Reactive Aldehydes 4-Hydroxy-2-nonenal and 4-Oxo-2-nonenal.

PubMed

Vazdar, Katarina; Vojta, Danijela; Margetić, Davor; Vazdar, Mario

2017-03-20

4-Hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE) are biologically important reactive aldehydes formed during oxidative stress in phospholipid bilayers. They are highly reactive species due to presence of several reaction centers and can react with amino acids in peptides and proteins, as well as phosphoethanolamine (PE) lipids, thus modifying their biological activity. The aim of this work is to study in a molecular detail the reactivity of HNE and ONE toward PE lipids in a simplified system containing only lipids and reactive aldehydes in dichloromethane as an inert solvent. We use a combination of quantum chemical calculations, 1 H NMR measurements, FT-IR spectroscopy, and mass spectrometry experiments and show that for both reactive aldehydes two types of chemical reactions are possible: formation of Michael adducts and Schiff bases. In the case of HNE, an initially formed Michael adduct can also undergo an additional cyclization step to a hemiacetal derivative, whereas no cyclization occurs in the case of ONE and a Michael adduct is identified. A Schiff base product initially formed when HNE is added to PE lipid can also further cyclize to a pyrrole derivative in contrast to ONE, where only a Schiff base product is isolated. The suggested reaction mechanism by quantum-chemical calculations is in a qualitative agreement with experimental yields of isolated products and is also additionally investigated by 1 H NMR measurements, FT-IR spectroscopy, and mass spectrometry experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usman, Yasir; Kim, Jinho; Muljadi, Eduard

Wake effects cause wind turbine generators (WTGs) within a wind power plant (WPP) to produce different levels of active power and subsequent reactive power capabilities. Further, the impedance between a WTG and the point of interconnection (POI)-which depends on the distance between them-impacts the WPP's reactive power injection capability at the POI. This paper proposes a voltage control scheme for a WPP based on the available reactive current of the doubly-fed induction generators (DFIGs) and its impacts on the POI to improve the reactive power injection capability of the WPP. In this paper, a design strategy for modifying the gainmore » of DFIG controller is suggested and the comprehensive properties of these control gains are investigated. In the proposed scheme, the WPP controller, which operates in a voltage control mode, sends the command signal to the DFIGs based on the voltage difference at the POI. The DFIG controllers, which operate in a voltage control mode, employ a proportional controller with a limiter. The gain of the proportional controller is adjusted depending on the available reactive current of the DFIG and the series impedance between the DFIG and the POI. The performance of the proposed scheme is validated for various disturbances such as a reactive load connection and grid fault using an EMTP-RV simulator. Furthermore, simulation results demonstrate that the proposed scheme promptly recovers the POI voltage by injecting more reactive power after a disturbance than the conventional scheme.« less

Integrating the Principles of Effective Intervention into Batterer Intervention Programming: The Case for Moving Toward More Evidence-Based Programming.

PubMed

Radatz, Dana L; Wright, Emily M

2016-01-01

The majority of batterer intervention program (BIP) evaluations have indicated they are marginally effective in reducing domestic violence recidivism. Meanwhile, correctional programs used to treat a variety of offenders (e.g., substance users, violent offenders, and so forth) that adhere to the "principles of effective intervention" (PEI) have reported significant reductions in recidivism. This article introduces the PEI-the principles on which evidence-based practices in correctional rehabilitation are based-and identifies the degree to which they are currently integrated into BIPs. The case is made that batterer programs could be more effective if they incorporate the PEI. Recommendations for further integration of the principles into BIPs are also provided. © The Author(s) 2015.

An efficient route to selective bio-oxidation catalysts: an iterative approach comprising modeling, diversification, and screening, based on CYP102A1.

PubMed

Seifert, Alexander; Antonovici, Mihaela; Hauer, Bernhard; Pleiss, Jürgen

2011-06-14

Perillyl alcohol is the terminal hydroxylation product of the cheap and readily available terpene, limonene. It has high potential as an anti-tumor substance, but is of limited availability. In principle, cytochrome P450 monooxygenases, such as the self-sufficient CYP102A1, are promising catalysts for the oxidation of limonene or other inert hydrocarbons. The wild-type enzyme converts (4R)-limonene to four different oxidation products; however, terminal hydroxylation at the allylic C7 is not observed. Here we describe a generic strategy to engineer this widely used enzyme to hydroxylate exclusively the exposed, but chemically less reactive, primary C7 in the presence of other reactive positions. The approach presented here turns CYP102A1 into a highly selective catalyst with a shifted product spectra by successive rounds of modeling, the design of small focused libraries, and screening. In the first round a minimal CYP102A1 mutant library was rationally designed. It contained variants with improved or strongly shifted regio-, stereo- and chemoselectivity, compared to wild-type. From this library the variant with the highest perillyl alcohol ratio was fine-tuned by two additional rounds of molecular modeling, diversification, and screening. In total only 29 variants needed to be screened to identify the triple mutant A264V/A238V/L437F that converts (4R)-limonene to perillyl alcohol with a selectivity of 97 %. Focusing mutagenesis on a small number of relevant positions identified by computational approaches is the key for efficient screening for enzyme selectivity. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards a rational approach for heavy-atom derivative screening in protein crystallography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agniswamy, Johnson; Joyce, M. Gordon; Hammer, Carl H.

2008-04-01

Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity of more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Heavy-atom derivatization is routinely used in protein structure determination and is thus of critical importance in structural biology. In order to replace the current trial-and-error heavy-atom derivative screening with a knowledge-based rational derivative-selection method, the reactivity ofmore » more than 40 heavy-atom compounds over a wide range of buffer and pH values was systematically examined using peptides which contained a single reactive amino-acid residue. Met-, Cys- and His-containing peptides were derivatized against Hg, Au and Pt compounds, while Tyr-, Glu-, Asp-, Asn- and Gln-containing peptides were assessed against Pb compounds. A total of 1668 reactive conditions were examined using mass spectrometry and were compiled into heavy-atom reactivity tables. The results showed that heavy-atom derivatization reactions are highly linked to buffer and pH, with the most accommodating buffer being MES at pH 6. A group of 21 compounds were identified as most successful irrespective of ligand or buffer/pH conditions. To assess the applicability of the peptide heavy-atom reactivity to proteins, lysozyme crystals were derivatized with a list of peptide-reactive compounds that included both known and new compounds for lysozyme derivatization. The results showed highly consistent heavy-atom reactivities between the peptides and lysozyme.« less

Introducing a new bond reactivity index: Philicities for natural bond orbitals.

PubMed

Sánchez-Márquez, Jesús; Zorrilla, David; García, Víctor; Fernández, Manuel

2017-12-22

In the present work, a new methodology defined for obtaining reactivity indices (philicities) is proposed. This is based on reactivity functions such as the Fukui function or the dual descriptor, and makes it possible to project the information from reactivity functions onto molecular orbitals, instead of onto the atoms of the molecule (atomic reactivity indices). The methodology focuses on the molecules' natural bond orbitals (bond reactivity indices) because these orbitals have the advantage of being localized, allowing the reaction site of an electrophile or nucleophile to be determined within a very precise molecular region. This methodology provides a "philicity" index for every NBO, and a representative set of molecules has been used to test the new definition. A new methodology has also been developed to compare the "finite difference" and the "frontier molecular orbital" approximations. To facilitate their use, the proposed methodology as well as the possibility of calculating the new indices have been implemented in a new version of UCA-FUKUI software. In addition, condensation schemes based on atomic populations of the "atoms in molecules" theory, the Hirshfeld population analysis, the approximation of Mulliken (with a minimal basis set) and electrostatic potential-derived charges have also been implemented, including the calculation of "bond reactivity indices" defined in previous studies. Graphical abstract A new methodology defined for obtaining bond reactivity indices (philicities) is proposed and makes it possible to project the information from reactivity functions onto molecular orbitals. The proposed methodology as well as the possibility of calculating the new indices have been implemented in a new version of UCA-FUKUI software. In addition, this version can use new atomic condensation schemes and new "utilities" have also been included in this second version.

An easy method for the determination of active concentrations of cholinesterase reactivators in blood samples: Application to the efficacy assessment of non quaternary reactivators compared to HI-6 and pralidoxime in VX-poisoned mice.

PubMed

Calas, André-Guilhem; Dias, José; Rousseau, Catherine; Arboléas, Mélanie; Touvrey-Loiodice, Mélanie; Mercey, Guillaume; Jean, Ludovic; Renard, Pierre-Yves; Nachon, Florian

2017-04-01

Organophosphorus nerve agents, like VX, are highly toxic due to their strong inhibition potency against acetylcholinesterase (AChE). AChE inhibited by VX can be reactivated using powerful nucleophilic molecules, most commonly oximes, which are one major component of the emergency treatment in case of nerve agent intoxication. We present here a comparative in vivo study on Swiss mice of four reactivators: HI-6, pralidoxime and two uncharged derivatives of 3-hydroxy-2-pyridinaldoxime that should more easily cross the blood-brain barrier and display a significant central nervous system activity. The reactivability kinetic profile of the oximes is established following intraperitoneal injection in healthy mice, using an original and fast enzymatic method based on the reactivation potential of oxime-containing plasma samples. HI-6 displays the highest reactivation potential whatever the conditions, followed by pralidoxime and the two non quaternary reactivators at the dose of 50 mg/kg bw. But these three last reactivators display equivalent reactivation potential at the same dose of 100 μmol/kg bw. Maximal reactivation potential closely correlates to surviving test results of VX intoxicated mice. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Emotional reactivity: Beware its involvement in traffic accidents.

PubMed

M'bailara, Katia; Atzeni, Thierry; Contrand, Benjamin; Derguy, Cyrielle; Bouvard, Manuel-Pierre; Lagarde, Emmanuel; Galéra, Cédric

2018-04-01

Reducing risk attributable to traffic accidents is a public health challenge. Research into risk factors in the area is now moving towards identification of the psychological factors involved, particularly emotional states. The aim of this study was to evaluate the link between emotional reactivity and responsibility in road traffic accidents. We hypothesized that the more one's emotional reactivity is disturbed, the greater the likelihood of being responsible for a traffic accident. This case-control study was based on a sample of 955 drivers injured in a motor vehicle crash. Responsibility levels were determined with a standardized method adapted from the quantitative Robertson and Drummer crash responsibility instrument. Emotional reactivity was assessed with the MATHYS. Hierarchical cluster analysis discriminated four distinctive driver's emotional reactivity profiles: basic emotional reactivity (54%), mild emotional hyper-reactivity (29%), emotional hyper-reactivity (11%) and emotional hypo-reactivity (6%). Drivers who demonstrated emotional hypo-reactivity had a 2.3-fold greater risk of being responsible for a traffic accident than those with basic emotional reactivity. Drivers' responsibility in traffic accidents depends on their emotional status. The latter can change the ability of drivers, modifying their behavior and thus increasing their propensity to exhibit risk behavior and to cause traffic accidents. Copyright © 2017 Elsevier B.V. All rights reserved.

[Biological effects of resveratrol and other constituents of wine].

PubMed

Kollár, P; Hotolová, H

2003-11-01

In recent years many scientific papers have been published concerning the positive effects of wine and its active principles, the polyphenol resveratrol being the most widely discussed compound. The results of epidemiological and experimental studies in man, animals, and in vitro have shown that polyphenols contained in wine, tea, fruit, and vegetables exert a positive effect on both the progression and regression of atherosclerosis, possess an anticancerogenic action, and due to their antioxidative effects they act against other processes connected with the reactive forms of oxygen production and lipid peroxydation in the blood plasma and membranes. Experimental findings have shown that resveratrol protects the cardiovascular system, affects lipid metabolism, and inhibits low-density lipoproteins (LDL) oxidation and blood platelet aggregation. In addition, this natural product is able to inhibit the growth of some tumours and possesses antiinflammatory properties and a number of other biological effects. This report aims to describe and characterize in a summary the biological properties of the principal active principles of wine--flavonoids and polyphenols, with a detailed focus on resveratrol, which has been described as the most interesting agent.

First-principles study of the effect of functional groups on polyaniline backbone

PubMed Central

Chen, X. P.; Jiang, J. K.; Liang, Q. H.; Yang, N.; Ye, H. Y.; Cai, M.; Shen, L.; Yang, D. G.; Ren, T. L.

2015-01-01

We present a first-principles density functional theory study focused on how the chemical and electronic properties of polyaniline are adjusted by introducing suitable substituents on a polymer backbone. Analyses of the obtained energy barriers, reaction energies and minimum energy paths indicate that the chemical reactivity of the polyaniline derivatives is significantly enhanced by protonic acid doping of the substituted materials. Further study of the density of states at the Fermi level, band gap, HOMO and LUMO shows that both the unprotonated and protonated states of these polyanilines are altered to different degrees depending on the functional group. We also note that changes in both the chemical and electronic properties are very sensitive to the polarity and size of the functional group. It is worth noting that these changes do not substantially alter the inherent chemical and electronic properties of polyaniline. Our results demonstrate that introducing different functional groups on a polymer backbone is an effective approach to obtain tailored conductive polymers with desirable properties while retaining their intrinsic properties, such as conductivity. PMID:26584671

[Cross reactivities between food antigens of plant or animal origin].

PubMed

Bakos, N; Nékám, K

2000-03-26

Knowledge about cross reactivities among food proteins of plant or animal origin is getting more and more important. Cross reaction provoking often clinical symptoms may be based on close taxonomical relations or on the presence of "archaic", ubiquiter protein structures preserved during phylogenesis. The most significant cross reactivities characterized by increasing incidence are between pollens and foods of plant origin and between latex and fruits.

Evaluation of Advanced Reactive Surface Area Estimates for Improved Prediction of Mineral Reaction Rates in Porous Media

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Mitnick, E. H.; Zhang, S.; Voltolini, M.; Yang, L.; Steefel, C. I.; Swift, A.; Cole, D. R.; Sheets, J.; Kneafsey, T. J.; Landrot, G.; Anovitz, L. M.; Mito, S.; Xue, Z.; Ajo Franklin, J. B.; DePaolo, D.

2015-12-01

CO2 sequestration in deep sedimentary formations is a promising means of reducing atmospheric CO2 emissions but the rate and extent of mineral trapping remains difficult to predict. Reactive transport models provide predictions of mineral trapping based on laboratory mineral reaction rates, which have been shown to have large discrepancies with field rates. This, in part, may be due to poor quantification of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area are ad hoc and typically based on grain size, adjusted several orders of magnitude to account for surface roughness and reactivity. This results in orders of magnitude discrepancies in estimated surface areas that directly translate into orders of magnitude discrepancies in model predictions. Additionally, natural systems can be highly heterogeneous and contain abundant nano- and micro-porosity, which can limit connected porosity and access to mineral surfaces. In this study, mineral-specific accessible surface areas are computed for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan). Accessible mineral surface areas are determined from a multi-scale image analysis including X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB. Powder and flow-through column laboratory experiments are performed and the evolution of solutes in the aqueous phase is tracked. Continuum-scale reactive transport models are used to evaluate the impact of reactive surface area on predictions of experimental reaction rates. Evaluated reactive surface areas include geometric and specific surface areas (eg. BET) in addition to their reactive-site weighted counterparts. The most accurate predictions of observed powder mineral dissolution rates were obtained through use of grain-size specific surface areas computed from a BET-based correlation. Effectively, this surface area reflects the grain-fluid contact area, or accessible surface area, in the powder dissolution experiment. In the model of the flow-through column experiment, the accessible mineral surface area, computed from the multi-scale image analysis, is evaluated in addition to the traditional surface area estimates.

Transport and Reactive Flow Modelling Using A Particle Tracking Method Based on Continuous Time Random Walks

NASA Astrophysics Data System (ADS)

Oliveira, R.; Bijeljic, B.; Blunt, M. J.; Colbourne, A.; Sederman, A. J.; Mantle, M. D.; Gladden, L. F.

2017-12-01

Mixing and reactive processes have a large impact on the viability of enhanced oil and gas recovery projects that involve acid stimulation and CO2 injection. To achieve a successful design of the injection schemes an accurate understanding of the interplay between pore structure, flow and reactive transport is necessary. Dependent on transport and reactive conditions, this complex coupling can also be dependent on initial rock heterogeneity across a variety of scales. To address these issues, we devise a new method to study transport and reactive flow in porous media at multiple scales. The transport model is based on an efficient Particle Tracking Method based on Continuous Time Random Walks (CTRW-PTM) on a lattice. Transport is modelled using an algorithm described in Rhodes and Blunt (2006) and Srinivasan et al. (2010); this model is expanded to enable for reactive flow predictions in subsurface rock undergoing a first-order fluid/solid chemical reaction. The reaction-induced alteration in fluid/solid interface is accommodated in the model through changes in porosity and flow field, leading to time dependent transport characteristics in the form of transit time distributions which account for rock heterogeneity change. This also enables the study of concentration profiles at the scale of interest. Firstly, we validate transport model by comparing the probability of molecular displacement (propagators) measured by Nuclear Magnetic Resonance (NMR) with our modelled predictions for concentration profiles. The experimental propagators for three different porous media of increasing complexity, a beadpack, a Bentheimer sandstone and a Portland carbonate, show a good agreement with the model. Next, we capture the time evolution of the propagators distribution in a reactive flow experiment, where hydrochloric acid is injected into a limestone rock. We analyse the time-evolving non-Fickian signatures for the transport during reactive flow and observe an increase in transport heterogeneity at latter times, representing the increase in rock heterogeneity. Evolution of transit time distribution is associated with the evolution of concentration profiles, thus highlighting the impact of initial rock structure on the reactive transport for a range of Pe and Da numbers.

Influence knowledge and behavior of TB medical personnels’ concordance principle based communications skill at primary healthcare, Medan, Indonesia

NASA Astrophysics Data System (ADS)

Wahyuni, A. S.; Soeroso, N. N.; Alona, I.; Yunanda, Y.; Siregar, I.

2018-03-01

Concordance behavior of TB management is a form of collaboration among doctors, personnel, and patients in treating TB. Approvalamong them could be achieved if credibility and policy occur. This study is aimed to analyze the influence of TB medical personnel’s concordance behaviour principle to patient obedience at primary health care in Medan.The design of this study was quasi experimental, focusing on interventional primary health care, which is those who applied concordance behaviour principle to non-interventionalprimary health care. The population is TB patients, starting from 18 years old, TB category I with positive Acid Fast Bacilli Smear Test (AFBST), and taking TB regimens at Medan. Seventy- four patients were selected to be samples. They had undergone interview based on validated concordance principle, knowledge, behavior, and treatment. Data were analyzed using chi- square. The percentage of knowledge, behavior of TB patient to the treatment is higher on interventional primary health care than noninterventional ones. Treatment awareness based on concordance principle is expected to planish DOTS-based TB programs.

Chemical Reactive Anchoring Lipids with Different Performance for Cell Surface Re-engineering Application.

PubMed

Vabbilisetty, Pratima; Boron, Mallorie; Nie, Huan; Ozhegov, Evgeny; Sun, Xue-Long

2018-02-28

Introduction of selectively chemical reactive groups at the cell surface enables site-specific cell surface labeling and modification opportunity, thus facilitating the capability to study the cell surface molecular structure and function and the molecular mechanism it underlies. Further, it offers the opportunity to change or improve a cell's functionality for interest of choice. In this study, two chemical reactive anchor lipids, phosphatidylethanolamine-poly(ethylene glycol)-dibenzocyclooctyne (DSPE-PEG 2000 -DBCO) and cholesterol-PEG-dibenzocyclooctyne (CHOL-PEG 2000 -DBCO) were synthesized and their potential application for cell surface re-engineering via lipid fusion were assessed with RAW 264.7 cells as a model cell. Briefly, RAW 264.7 cells were incubated with anchor lipids under various concentrations and at different incubation times. The successful incorporation of the chemical reactive anchor lipids was confirmed by biotinylation via copper-free click chemistry, followed by streptavidin-fluorescein isothiocyanate binding. In comparison, the cholesterol-based anchor lipid afforded a higher cell membrane incorporation efficiency with less internalization than the phospholipid-based anchor lipid. Low cytotoxicity of both anchor lipids upon incorporation into the RAW 264.7 cells was observed. Further, the cell membrane residence time of the cholesterol-based anchor lipid was evaluated with confocal microscopy. This study suggests the potential cell surface re-engineering applications of the chemical reactive anchor lipids.

Mass spectrometry in the characterization of reactive metal alkoxides.

PubMed

Peruzzo, Valentina; Chiurato, Matteo Andrea; Favaro, Monica; Tomasin, Patrizia

2018-01-01

Metal alkoxides are metal-organic compounds characterized by the presence of MOC bonds (M = metal). Their chemistry seems to be, in principle, relatively simple but the number of possible reactant species arising as a consequence of their behavior is very remarkable. The physico-chemical properties of metal alkoxides are determined by many different parameters, the most important ones being the electronegativity of the metal, the ramification of the ligand, and the acidity of the corresponding alcohol. Their reactivity makes them suitable and versatile candidates for many applications, including homogeneous catalysis, synthesis of new ceramic materials through the sol-gel process and, recently, also for Cultural Heritage. Metal alkoxides are characterized by a strong tendency to give clusters and/or oligomers through oxo-bridges. Mass spectrometry has been successfully employed for the characterization of metal alkoxides in the gas-phase. Electron ionization (EI) allowed the assessment of the molecular weight and of the most relevant decomposition pathways giving information on the relative bond strength of differently substituted molecules. On the other hand, information on the reactivity in solution of these molecules have been obtained by electrospray ionization (ESI)-matrix assisted laser desorption ionization (MALDI) experiments performed on their reaction products. These data were relevant to investigate the sol-gel process. In this review, these aspects are described and the results obtained are critically evaluated. © 2016 Wiley Periodicals, Inc. Mass Spec Rev. © 2016 Wiley Periodicals, Inc.

On the Theory of Reactive Mixtures for Modeling Biological Growth

PubMed Central

Ateshian, Gerard A.

2013-01-01

Mixture theory, which can combine continuum theories for the motion and deformation of solids and fluids with general principles of chemistry, is well suited for modeling the complex responses of biological tissues, including tissue growth and remodeling, tissue engineering, mechanobiology of cells and a variety of other active processes. A comprehensive presentation of the equations of reactive mixtures of charged solid and fluid constituents is lacking in the biomechanics literature. This study provides the conservation laws and entropy inequality, as well as interface jump conditions, for reactive mixtures consisting of a constrained solid mixture and multiple fluid constituents. The constituents are intrinsically incompressible and may carry an electrical charge. The interface jump condition on the mass flux of individual constituents is shown to define a surface growth equation, which predicts deposition or removal of material points from the solid matrix, complementing the description of volume growth described by the conservation of mass. A formu-lation is proposed for the reference configuration of a body whose material point set varies with time. State variables are defined which can account for solid matrix volume growth and remodeling. Constitutive constraints are provided on the stresses and momentum supplies of the various constituents, as well as the interface jump conditions for the electrochem cal potential of the fluids. Simplifications appropriate for biological tissues are also proposed, which help reduce the governing equations into a more practical format. It is shown that explicit mechanisms of growth-induced residual stresses can be predicted in this framework. PMID:17206407

Examination of a dual-process model predicting riding with drinking drivers.

PubMed

Hultgren, Brittney A; Scaglione, Nichole M; Cleveland, Michael J; Turrisi, Rob

2015-06-01

Nearly 1 in 5 of the fatalities in alcohol-related crashes are passengers. Few studies have utilized theory to examine modifiable psychosocial predictors of individuals' tendencies to be a passenger in a vehicle operated by a driver who has consumed alcohol. This study used a prospective design to test a dual-process model featuring reasoned and reactive psychological influences and psychosocial constructs as predictors of riding with drinking drivers (RWDD) in a sample of individuals aged 18 to 21. College students (N = 508) completed web-based questionnaires assessing RWDD, psychosocial constructs (attitudes, expectancies, and norms), and reasoned and reactive influences (intentions and willingness) at baseline (the middle of the spring semester) and again 1 and 6 months later. Regression was used to analyze reasoned and reactive influences as proximal predictors of RWDD at the 6-month follow-up. Subsequent analyses examined the relationship between the psychosocial constructs as distal predictors of RWDD and the mediation effects of reasoned and reactive influences. Both reasoned and reactive influences predicted RWDD, while only the reactive influence had a significant unique effect. Reactive influences significantly mediated the effects of peer norms, attitudes, and drinking influences on RWDD. Nearly all effects were constant across gender except parental norms (significant for females). Findings highlight that the important precursors of RWDD were reactive influences, attitudes, and peer and parent norms. These findings suggest several intervention methods, specifically normative feedback interventions, parent-based interventions, and brief motivational interviewing, may be particularly beneficial in reducing RWDD. Copyright © 2015 by the Research Society on Alcoholism.

Pyridoxylamine reactivity kinetics as an amine based nucleophile for screening electrophilic dermal sensitizers

PubMed Central

Chipinda, Itai; Mbiya, Wilbes; Adigun, Risikat Ajibola; Morakinyo, Moshood K.; Law, Brandon F.; Simoyi, Reuben H.; Siegel, Paul D.

2015-01-01

Chemical allergens bind directly, or after metabolic or abiotic activation, to endogenous proteins to become allergenic. Assessment of this initial binding has been suggested as a target for development of assays to screen chemicals for their allergenic potential. Recently we reported a nitrobenzenethiol (NBT) based method for screening thiol reactive skin sensitizers, however, amine selective sensitizers are not detected by this assay. In the present study we describe an amine (pyridoxylamine (PDA)) based kinetic assay to complement the NBT assay for identification of amine-selective and non-selective skin sensitizers. UV-Vis spectrophotometry and fluorescence were used to measure PDA reactivity for 57 chemicals including anhydrides, aldehydes, and quinones where reaction rates ranged from 116 to 6.2 × 10−6 M−1 s−1 for extreme to weak sensitizers, respectively. No reactivity towards PDA was observed with the thiol-selective sensitizers, non-sensitizers and prohaptens. The PDA rate constants correlated significantly with their respective murine local lymph node assay (LLNA) threshold EC3 values (R2 = 0.76). The use of PDA serves as a simple, inexpensive amine based method that shows promise as a preliminary screening tool for electrophilic, amine-selective skin sensitizers. PMID:24333919

Impact Ignition and Combustion Behavior of Amorphous Metal-Based Reactive Composites

NASA Astrophysics Data System (ADS)

Mason, Benjamin; Groven, Lori; Son, Steven

2013-06-01

Recently published molecular dynamic simulations have shown that metal-based reactive powder composites consisting of at least one amorphous component could lead to improved reaction performance due to amorphous materials having a zero heat of fusion, in addition to having high energy densities and potential uses such as structural energetic materials and enhanced blast materials. In order to investigate the feasibility of these systems, thermochemical equilibrium calculations were performed on various amorphous metal/metalloid based reactive systems with an emphasis on commercially available or easily manufactured amorphous metals, such as Zr and Ti based amorphous alloys in combination with carbon, boron, and aluminum. Based on the calculations and material availability material combinations were chosen. Initial materials were either mixed via a Resodyn mixer or mechanically activated using high energy ball milling where the microstructure of the milled material was characterized using x-ray diffraction, optical microscopy and scanning electron microscopy. The mechanical impact response and combustion behavior of select reactive systems was characterized using the Asay shear impact experiment where impact ignition thresholds, ignition delays, combustion velocities, and temperatures were quantified, and reported. Funding from the Defense Threat Reduction Agency (DTRA), Grant Number HDTRA1-10-1-0119. Counter-WMD basic research program, Dr. Suhithi M. Peiris, program director is gratefully acknowledged.

Practice-Based Evidence: Delivering What Works

ERIC Educational Resources Information Center

Brendtro, Larry K.; Mitchell, Martin L.

2012-01-01

Many methods claim to be Evidence-Based Practices. Yet success comes not from a particular practice, but principles that underlie all effective helping. This article uses the principle of consilience to tap knowledge from science, values, and practical experience.

State of the science of maternal-infant bonding: a principle-based concept analysis.

PubMed

Bicking Kinsey, Cara; Hupcey, Judith E

2013-12-01

to provide a principle-based analysis of the concept of maternal-infant bonding. principle-based method of concept analysis for which the data set included 44 articles published in the last decade from Pubmed, CINAHL, and PyschINFO/PsychARTICLES. literature inclusion criteria were English language, articles published in the last decade, peer-reviewed journal articles and commentary on published work, and human populations. after a brief review of the history of maternal-infant bonding, a principle-based concept analysis was completed to examine the state of the science with regard to this concept. The concept was critically examined according to the clarity of definition (epistemological principle), applicability of the concept (pragmatic principle), consistency in use and meaning (linguistic principle), and differentiation of the concept from related concepts (logical principle). Analysis of the concept revealed: (1) Maternal-infant bonding describes maternal feelings and emotions towards her infant. Evidence that the concept encompasses behavioural or biological components was limited. (2) The concept is clearly operationalised in the affective domain. (3) Maternal-infant bonding is linguistically confused with attachment, although the boundaries between the concepts are clearly delineated. despite widespread use of the concept, maternal-infant bonding is at times superficially developed and subject to confusion with related concepts. Concept clarification is warranted. A theoretical definition of the concept of maternal-infant bonding was developed to aid in the clarification, but more research is necessary to further clarify and advance the concept. nurse midwives and other practitioners should use the theoretical definition of maternal-infant bonding as a preliminary guide to identification and understanding of the concept in clinical practice. Copyright © 2013 Elsevier Ltd. All rights reserved.

STATE OF THE SCIENCE OF MATERNAL-INFANT BONDING: A PRINCIPLE-BASED CONCEPT ANALYSIS

PubMed Central

Bicking Kinsey, Cara; Hupcey, Judith E.

2013-01-01

Objective To provide a principle-based analysis of the concept of maternal-infant bonding. Design Principle-based method of concept analysis for which the data set included 44 articles published in the last decade from Pubmed, CINAHL, and PyschINFO/PsychARTICLES. Setting Literature inclusion criteria were English language, articles published in the last decade, peer-reviewed journal articles and commentary on published work, and human populations. Measurement and Findings After brief review of the history of maternal-infant bonding, a principle-based concept analysis was completed to examine the state of the science with regard to this concept. The concept was critically examined according to the clarity of definition (epistemological principle), applicability of the concept (pragmatic principle), consistency in use and meaning (linguistic principle), and differentiation of the concept from related concepts (logical principle). Analysis of the concept revealed: (1) maternal-infant bonding describes maternal feelings and emotions towards her infant. Evidence that the concept encompasses behavioral or biological components was limited; (2) the concept is clearly operationalized in the affective domain; and (3) maternal-infant bonding is linguistically confused with attachment, although the boundaries between the concepts are clearly delineated. Key Conclusion Despite widespread use of the concept, maternal-infant bonding is at times superficially developed and subject to confusion with related concepts. Concept clarification is warranted. A theoretical definition of the concept of maternal-infant bonding was developed to aid in the clarification, but more research is necessary to further clarify and advance the concept. Implications for Practice Nurse midwives and other practitioners should use the theoretical definition of maternal-infant bonding as a preliminary guide to identification and understanding of the concept in clinical practice. PMID:23452661

Analysis of the Association Between Motor and Anthropometric Variables with Change of Direction Speed and Reactive Agility Performance

PubMed Central

Sattler, Tine; Sekulić, Damir; Spasić, Miodrag; Perić, Mia; Krolo, Ante; Uljević, Ognjen; Kondrič, Miran

2015-01-01

There is an evident lack of studies examining the factors associated with reactive agility performances. The aim of this study was to evaluate the association between anthropometrics, body composition, jumping capacity, reactive strength, and balance with a stop-and-go change of direction speed (CODS) and reactive agility. The total sample comprised 39 male (body height: 182.95 ± 5.19 cm; body mass: 80.66 ± 7.69 kg) and 34 female (body height: 171.45 ± 6.81 cm; body mass: 61.95 ± 6.70 kg) college-level athletes (21.9 ± 1.9 years of age). The variables included body height, body mass, the percentage of body fat (BF%), balance as measured by an overall-stability index, the countermovement jump (CMJ), a reactive-strength index (RSI), stop-and-go reactive agility, and stop-and-go CODS. To define the associations between motor and anthropometric variables with CODS and reactive agility, the participants were clustered into three achievement groups based on their CODS and reactive agility performances. The ANOVA showed a significant difference between the CODS-based achievement groups for the CMJ (F test = 3.45 and 3.60 for males and females, respectively; p < 0.05), the RSI (F test = 6.94 and 5.29 for males and females, respectively; p < 0.05), and balance (F test = 3.47; p < 0.05 for males). In females, the reactive agility achievement groups differed significantly in the RSI (F test = 6.46; p < 0.05), the CMJ (F test = 4.35; p < 0.05) and BF% (F test = 4.07; p < 0.05), which is further confirmed by discriminant canonical analysis (Can R = 0.74; p < 0.05). The results confirm the need for independent evaluation and training for both CODS and reactive agility performance in sports. PMID:26557198

Evaluation of a computer-assisted, kinetics-based enzyme-linked immunosorbent assay for detection of coronavirus antibodies in cats.

PubMed Central

Barlough, J E; Jacobson, R H; Downing, D R; Marcella, K L; Lynch, T J; Scott, F W

1983-01-01

A computer-assisted, kinetics-based enzyme-linked immunosorbent assay was adapted for the detection of coronavirus antibodies in feline serum. An alkaline antigen diluent (carbonate-bicarbonate buffer, pH 9.6) used in initial experiments produced diffuse, nonspecific color reactions in both viral and control antigen cuvettes which were correlated, paradoxically, with coronavirus antibody levels in test sera. These interfering reactions were minimized by use of lower-pH antigen diluents such as water and phosphate-buffered saline. Background kinetics-based enzyme-linked immunosorbent assay reactivity directed against a noncoronaviral component of antigen tissue culture fluids could then detected in numerous sera, particularly in samples with lower titers. Much of this reactivity was shown to be associated with bovine gamma globulins in cell culture fluid. It was not serum lot or species specific, since a variety of bovine serum lots as well as individual lots of serum from other mammalian and avian species reacted. Reactivity was markedly reduced when cells for antigen preparation were grown in gamma globulin-free bovine serum. Generation of corrected slope values from the kinetics-based enzyme-linked immunosorbent assay made it possible to correct for residual background reactivity in individual test sera and thus eliminate a potentially major source of false-positive reactions. Collectively, these studies indicated that the control of nonspecific reactivity in feline coronavirus serology is absolutely essential to obtain useful estimates of specific antibody responses. PMID:6300184

Evaluation of a computer-assisted, kinetics-based enzyme-linked immunosorbent assay for detection of coronavirus antibodies in cats.

PubMed

Barlough, J E; Jacobson, R H; Downing, D R; Marcella, K L; Lynch, T J; Scott, F W

1983-02-01

A computer-assisted, kinetics-based enzyme-linked immunosorbent assay was adapted for the detection of coronavirus antibodies in feline serum. An alkaline antigen diluent (carbonate-bicarbonate buffer, pH 9.6) used in initial experiments produced diffuse, nonspecific color reactions in both viral and control antigen cuvettes which were correlated, paradoxically, with coronavirus antibody levels in test sera. These interfering reactions were minimized by use of lower-pH antigen diluents such as water and phosphate-buffered saline. Background kinetics-based enzyme-linked immunosorbent assay reactivity directed against a noncoronaviral component of antigen tissue culture fluids could then detected in numerous sera, particularly in samples with lower titers. Much of this reactivity was shown to be associated with bovine gamma globulins in cell culture fluid. It was not serum lot or species specific, since a variety of bovine serum lots as well as individual lots of serum from other mammalian and avian species reacted. Reactivity was markedly reduced when cells for antigen preparation were grown in gamma globulin-free bovine serum. Generation of corrected slope values from the kinetics-based enzyme-linked immunosorbent assay made it possible to correct for residual background reactivity in individual test sera and thus eliminate a potentially major source of false-positive reactions. Collectively, these studies indicated that the control of nonspecific reactivity in feline coronavirus serology is absolutely essential to obtain useful estimates of specific antibody responses.

A DFIG Islanding Detection Scheme Based on Reactive Power Infusion

NASA Astrophysics Data System (ADS)

Wang, M.; Liu, C.; He, G. Q.; Li, G. H.; Feng, K. H.; Sun, W. W.

2017-07-01

A lot of research has been done on photovoltaic (the “PV”) power system islanding detection in recent years. As a comparison, much less attention has been paid to islanding in wind turbines. Meanwhile, wind turbines can work in islanding conditions for quite a long period, which can be harmful to equipments and cause safety hazards. This paper presents and examines a double fed introduction generation (the “DFIG”) islanding detection scheme based on feedback of reactive power and frequency and uses a trigger signal of reactive power infusion which can be obtained by dividing the voltage total harmonic distortion (the "THD") by the voltage THD of last cycle to avoid the deterioration of power quality. This DFIG islanding detection scheme uses feedback of reactive power current loop to amplify the frequency differences in islanding and normal conditions. Simulation results show that the DFIG islanding detection scheme is effective.

Effects of thermomechanical processing on strength and toughness of iron - 12-percent-nickel - reactive metal alloys at -196 C

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Witzke, W. R.

1978-01-01

Thermomechanical processing (TMP) was evaluated as a method of strengthening normally tough iron-12-nickel-reactive metal alloys at cryogenic temperatures. Five iron-12 nickel alloys with reactive metal additions of aluminum, niobium, titanium, vanadium, and aluminum plus niobium were investigated. Primary evaluation was based on the yield strength and fracture toughness of the thermomechanically processed alloys at -196 C.

A physiological model for interpretation of arterial spin labeling reactive hyperemia of calf muscles.

PubMed

Chen, Hou-Jen; Wright, Graham A

2017-01-01

To characterize and interpret arterial spin labeling (ASL) reactive hyperemia of calf muscles for a better understanding of the microcirculation in peripheral arterial disease (PAD), we present a physiological model incorporating oxygen transport, tissue metabolism, and vascular regulation mechanisms. The model demonstrated distinct effects between arterial stenoses and microvascular dysfunction on reactive hyperemia, and indicated a higher sensitivity of 2-minute thigh cuffing to microvascular dysfunction than 5-minute cuffing. The recorded perfusion responses in PAD patients (n = 9) were better differentiated from the normal subjects (n = 7) using the model-based analysis rather than characterization using the apparent peak and time-to-peak of the responses. The analysis results suggested different amounts of microvascular disease within the patient group. Overall, this work demonstrates a novel analysis method and facilitates understanding of the physiology involved in ASL reactive hyperemia. ASL reactive hyperemia with model-based analysis may be used as a noninvasive microvascular assessment in the presence of arterial stenoses, allowing us to look beyond the macrovascular disease in PAD. A subgroup who will have a poor prognosis after revascularization in the patients with critical limb ischemia may be associated with more severe microvascular diseases, which may potentially be identified using ASL reactive hyperemia.

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions.

PubMed

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly N; Kim, Young-Jin; Jardine, Philip M; Watson, David B

2007-06-16

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing N(E) equilibrium reactions and a set of reactive transport equations of M-N(E) kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.

Hierarchical Control Scheme for Improving Transient Voltage Recovery of a DFIG-Based WPP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jinho; Muljadi, Eduard; Kang, Yong Cheol

Modern grid codes require that wind power plants (WPPs) inject reactive power according to the voltage dip at a point of interconnection (POI). This requirement helps to support a POI voltage during a fault. However, if a fault is cleared, the POI and wind turbine generator (WTG) voltages are likely to exceed acceptable levels unless the WPP reduces the injected reactive power quickly. This might deteriorate the stability of a grid by allowing the disconnection of WTGs to avoid any damage. This paper proposes a hierarchical control scheme of a doubly-fed induction generator (DFIG)-based WPP. The proposed scheme aims tomore » improve the reactive power injecting capability during the fault and suppress the overvoltage after the fault clearance. To achieve the former, an adaptive reactive power-to-voltage scheme is implemented in each DFIG controller so that a DFIG with a larger reactive power capability will inject more reactive power. To achieve the latter, a washout filter is used to capture a high frequency component contained in the WPP voltage, which is used to remove the accumulated values in the proportional-integral controllers. Test results indicate that the scheme successfully supports the grid voltage during the fault, and recovers WPP voltages without exceeding the limit after the fault clearance.« less

Quantification of EEG reactivity in comatose patients.

PubMed

Hermans, Mathilde C; Westover, M Brandon; van Putten, Michel J A M; Hirsch, Lawrence J; Gaspard, Nicolas

2016-01-01

EEG reactivity is an important predictor of outcome in comatose patients. However, visual analysis of reactivity is prone to subjectivity and may benefit from quantitative approaches. In EEG segments recorded during reactivity testing in 59 comatose patients, 13 quantitative EEG parameters were used to compare the spectral characteristics of 1-minute segments before and after the onset of stimulation (spectral temporal symmetry). Reactivity was quantified with probability values estimated using combinations of these parameters. The accuracy of probability values as a reactivity classifier was evaluated against the consensus assessment of three expert clinical electroencephalographers using visual analysis. The binary classifier assessing spectral temporal symmetry in four frequency bands (delta, theta, alpha and beta) showed best accuracy (Median AUC: 0.95) and was accompanied by substantial agreement with the individual opinion of experts (Gwet's AC1: 65-70%), at least as good as inter-expert agreement (AC1: 55%). Probability values also reflected the degree of reactivity, as measured by the inter-experts' agreement regarding reactivity for each individual case. Automated quantitative EEG approaches based on probabilistic description of spectral temporal symmetry reliably quantify EEG reactivity. Quantitative EEG may be useful for evaluating reactivity in comatose patients, offering increased objectivity. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Total OH reactivity measurements in ambient air in a southern Rocky Mountain ponderosa pine forest during BEACHON-SRM08 summer campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakashima, Yoshihiro; Kato, Shungo; Greenberg, Jim

2014-03-01

Total OH reactivity was measured during the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Southern Rocky Mountain 2008 field campaign (BEACHON-SRM08) held at Manitou Experimental Forest (MEF) in Colorado USA during the summer season in August, 2008. The averaged total OH reactivity was 6.8 s-1, smaller than that measured in urban or suburban areas, while sporadically high OH reactivity was also observed during some evenings. The total OH reactivity measurements were accompanied by observations of traces species such as CO, NO, NOy, O3 and SO2 and VOCs. From the calculation of OH reactivity based on the analysis ofmore » these trace species, 35.3-46.3% of OH reactivity for VOCs came from biogenic species that are dominated by 2-methyl-3-butene-2-ol (MBO), and monoterpenes. MBO was the most prominent contribution to OH reactivity of any other trace species. A comparison of observed and calculated OH reactivity shows that the calculated OH reactivity is 29.5-34.8% less than the observed value, implying the existence of missing OH sink. One of the candidates of missing OH was thought to be the oxidation products of biogenic species.« less

DefenseLink.mil - Special Report - Travels With Gates

Science.gov Websites

relationship between the U.S. and Thailand is based on shared democratic principles. Defense Dept. photo by U.S military-to-military relationship is based on shared democratic principles. more» Secretary, Chairman

The Frog Vestibular System as a Model for Lesion-Induced Plasticity: Basic Neural Principles and Implications for Posture Control

PubMed Central

Lambert, François M.; Straka, Hans

2011-01-01

Studies of behavioral consequences after unilateral labyrinthectomy have a long tradition in the quest of determining rules and limitations of the central nervous system (CNS) to exert plastic changes that assist the recuperation from the loss of sensory inputs. Frogs were among the first animal models to illustrate general principles of regenerative capacity and reorganizational neural flexibility after a vestibular lesion. The continuous successful use of the latter animals is in part based on the easy access and identifiability of nerve branches to inner ear organs for surgical intervention, the possibility to employ whole brain preparations for in vitro studies and the limited degree of freedom of postural reflexes for quantification of behavioral impairments and subsequent improvements. Major discoveries that increased the knowledge of post-lesional reactive mechanisms in the CNS include alterations in vestibular commissural signal processing and activation of cooperative changes in excitatory and inhibitory inputs to disfacilitated neurons. Moreover, the observed increase of synaptic efficacy in propriospinal circuits illustrates the importance of limb proprioceptive inputs for postural recovery. Accumulated evidence suggests that the lesion-induced neural plasticity is not a goal-directed process that aims toward a meaningful restoration of vestibular reflexes but rather attempts a survival of those neurons that have lost their excitatory inputs. Accordingly, the reaction mechanism causes an improvement of some components but also a deterioration of other aspects as seen by spatio-temporally inappropriate vestibulo-motor responses, similar to the consequences of plasticity processes in various sensory systems and species. The generality of the findings indicate that frogs continue to form a highly amenable vertebrate model system for exploring molecular and physiological events during cellular and network reorganization after a loss of vestibular function. PMID:22518109

Hydrotectonics; principles and relevance

USGS Publications Warehouse

Kopf, R.W.

1982-01-01

Hydrotectonics combines the principles of hydraulics and rock mechanics. The hypothesis assumes that: (1) no faults are truly planar, (2) opposing noncongruent wavy wallrock surfaces form chambers and bottlenecks along the fault, and (3) most thrusting occurs beneath the water table. These physical constraints permit the following dynamics. Shear displacement accompanying faulting must constantly change the volume of each chamber. Addition of ground water liquefies dry fault breccia to a heavy incompressible viscous muddy breccia I call fault slurry. When the volume of a chamber along a thrust fault decreases faster than its fault slurry can escape laterally, overpressurized slurry is hydraulically injected into the base of near-vertical fractures in the otherwise impervious overriding plate. Breccia pipes commonly form where such fissures intersect. Alternating decrease and increase in volume of the chamber subjects this injection slurry to reversible surges that not only raft and abrade huge clasts sporadically spalled from the walls of the conduit but also act as a forceful hydraulic ram which periodically widens the conduit and extends its top. If the pipe perforates a petroleum reservoir, leaking hydrocarbons float to its top. Sudden faulting may generate a powerful water hammer that can be amplified at some distal narrow ends of the anastomosing plumbing system, where the shock may produce shatter cones. If vented on the Earth's surface, the muddy breccia, now called extrusion slurry, forms a mud volcano. This hypothesis suggests that many highly disturbed features presently attributed to such catastrophic processes as subsurface explosions or meteorite impacts are due to the rheology of tectonic slurry in an intermittently reactivated pressure-relief tube rooted in a powerful reciprocating hydrotectonic pump activated by a long-lived deep-seated thrust fault.

A Comparative Analysis of the Minuteman Education Programs as Currently Offered at Six SAC Bases.

DTIC Science & Technology

1980-06-01

Principles of Marketing 3 Business Statistics 3 Business Law 3 Management Total... Principles of Marketing 3 Mathematics Methods I Total prerequisite hours 26 Required Graduate Courses Policy Formulation and Administration 3 Management...Business and Economic Statistics 3 Intermediate Business and Economic Statistics 3 Principles of Management 3 Corporation Finance 3 Principles of Marketing

CRISPR-Cas9-based target validation for p53-reactivating model compounds

PubMed Central

Wanzel, Michael; Vischedyk, Jonas B; Gittler, Miriam P; Gremke, Niklas; Seiz, Julia R; Hefter, Mirjam; Noack, Magdalena; Savai, Rajkumar; Mernberger, Marco; Charles, Joël P; Schneikert, Jean; Bretz, Anne Catherine; Nist, Andrea; Stiewe, Thorsten

2015-01-01

Inactivation of the p53 tumor suppressor by Mdm2 is one of the most frequent events in cancer, so compounds targeting the p53-Mdm2 interaction are promising for cancer therapy. Mechanisms conferring resistance to p53-reactivating compounds are largely unknown. Here we show using CRISPR-Cas9–based target validation in lung and colorectal cancer that the activity of nutlin, which blocks the p53-binding pocket of Mdm2, strictly depends on functional p53. In contrast, sensitivity to the drug RITA, which binds the Mdm2-interacting N terminus of p53, correlates with induction of DNA damage. Cells with primary or acquired RITA resistance display cross-resistance to DNA crosslinking compounds such as cisplatin and show increased DNA cross-link repair. Inhibition of FancD2 by RNA interference or pharmacological mTOR inhibitors restores RITA sensitivity. The therapeutic response to p53-reactivating compounds is therefore limited by compound-specific resistance mechanisms that can be resolved by CRISPR-Cas9-based target validation and should be considered when allocating patients to p53-reactivating treatments. PMID:26595461

Evaluation of Contribution for Voltage Control Ancillary Services Based on Social Surplus

NASA Astrophysics Data System (ADS)

Ueki, Yuji; Hara, Ryoichi; Kita, Hiroyuki; Hasegawa, Jun

Reactive power supply plays an important role in active power supply with adequate system voltages. Various pricing mechanism for reactive power supply have been developed and some of them are adopted in some power systems, however they are in a trial stage. The authors also focus on development of a pricing method for reactive power ancillary services. This problem involves two technical issues: rational estimation of the cost associated with reactive power supply and fair and transparent allocation of the estimated cost among the market participants. This paper proposes methods for evaluating the contribution of generators and demands.

Theoretical Principles to Guide the Teaching of Adjectives to Children Who Struggle With Word Learning: Synthesis of Experimental and Naturalistic Research With Principles of Learning Theory.

PubMed

Ricks, Samantha L; Alt, Mary

2016-07-01

The purpose of this tutorial is to provide clinicians with a theoretically motivated and evidence-based approach to teaching adjectives to children who struggle with word learning. Given that there are almost no treatment studies to guide this topic, we have synthesized findings from experimental and theoretical literature to come up with a principles-based approach to treatment. We provide a sample lesson plan, incorporating our 3 theoretical principles, and describe the materials chosen and methods used during treatment and assessment. This approach is theoretically motivated, but it needs to be empirically tested.

Evaluating Multiple Drivers of Soil Organic Matter Lability and Structure in a Sub-Alpine Forest Ecosystem

NASA Astrophysics Data System (ADS)

Hall, E.; Fegel, T. S., II; Boot, C. M.

2014-12-01

Aeolian deposition of reactive nitrogen (N) is reaching even the most remote ecosystems. There has been an abundance of research investigating how these subsidies of reactive N may alter fundamental ecosystem characteristics such as soil organic matter (SOM) pool size. Previous studies have reported that additions of reactive N have the potential to both increase and decrease SOM content. While there are a series of different variables that may affect the size of the SOM pool it has been suggested that the lability or recalcitrance of the SOM may be related to its chemical composition (kind and relative abundance of constituent molecules). To address this we sampled 6 experimental plots in a sub-alpine forest in Rocky Mountain National Park (3 control and 3 treated with reactive N for 18 years) during two months in the summers of 2011 and 2012. We found the SOM content of the control plots was greater than that of the experimental plots. To assess lability of each SOM sample we extracted the SOM from each plot with water and incubated the dissolved organic carbon with a common aquatic microbial community from a lake within the watershed. To assess structure of the SOM pool we used ultra performance liquid chromatography (UPLC) coupled with MS of each extract before incubation with the bacterial community. The dissolved component of the SOM showed clear differences in lability both in total quantity and rate of decomposition during incubation with aquatic microorganisms. Principle components analysis indicated season was a stronger driver of DOM composition than fertilization, describing the majority of the variability between July and September 2012. When samples were considered within a season and year there were additional differences in both lability and composition of DOM. Here we evaluate the relative influence of inter- and intra-annual variability and reactive N on both the characteristics and composition of SOM. By linking UPLC-MS with a functional assay of lability we attempt to define chemical characteristics of lability that can be assessed across ecosystems. Doing so will allow us to better understand linked biogeochemical cycles (C and N) across a wide range of soil ecosystems.

Sexual Orientation Modulates Endocrine Stress Reactivity

PubMed Central

Juster, Robert-Paul; Hatzenbuehler, Mark L.; Mendrek, Adrianna; Pfaus, James G.; Smith, Nathan Grant; Johnson, Philip Jai; Lefebvre-Louis, Jean-Philippe; Raymond, Catherine; Marin, Marie-France; Sindi, Shireen; Lupien, Sonia J.; Pruessner, Jens C.

2015-01-01

BACKGROUND Biological sex differences and sociocultural gender diversity influence endocrine stress reactivity. Although numerous studies have shown that men typically activate stronger stress responses than women when exposed to laboratory-based psychosocial stressors, it is unclear whether sexual orientation further modulates stress reactivity. Given that lesbian, gay, and bisexual (LGB) individuals frequently report heightened distress secondary to stigma-related stressors, we investigated whether cortisol stress reactivity differs between LGB individuals and heterosexual individuals in response to a well-validated psychosocial stressor. METHODS The study population comprised 87 healthy adults (mean age, 25 years) who were grouped according to their biological sex and their gendered sexual orientation: lesbian/bisexual women (n = 20), heterosexual women (n = 21), gay/bisexual men (n = 26), and heterosexual men (n = 20). Investigators collected 10 salivary cortisol samples throughout a 2-hour afternoon visit involving exposure to the Trier Social Stress Test modified to maximize between-sex differences. RESULTS Relative to heterosexual women, lesbian/bisexual women showed higher cortisol stress reactivity 40 min after exposure to the stressor. In contrast, gay/bisexual men displayed lower overall cortisol concentrations throughout testing compared with heterosexual men. Main findings were significant while adjusting for sex hormones (estradiol-to-progesterone ratio in women and testosterone in men), age, self-esteem, and disclosure status (whether LGB participants had completed their “coming out”). CONCLUSIONS Our results provide novel evidence for gender-based modulation of cortisol stress reactivity based on sexual orientation that goes beyond well-established between-sex differences. This study raises several important avenues for future research related to the physiologic functioning of LGB populations and gender diversity more broadly. PMID:25444167

Accounting for the Decreasing Denitrification Potential of Aquifers in Travel-Time Based Reactive-Transport Models of Nitrate

NASA Astrophysics Data System (ADS)

Cirpka, O. A.; Loschko, M.; Wöhling, T.; Rudolph, D. L.

2017-12-01

Excess nitrate concentrations pose a threat to drinking-water production from groundwater in all regions of intensive agriculture worldwide. Natural organic matter, pyrite, and other reduced constituents of the aquifer matrix can be oxidized by aerobic and denitrifying bacteria, leading to self-cleaning of groundwater. Various studies have shown that the heterogeneity of both hydraulic and chemical aquifer properties influence the reactive behavior. Since the exact spatial distributions of these properties are not known, predictions on the temporal evolution of nitrate should be probabilistic. However, the computational effort of pde-based, spatially explicit multi-component reactive-transport simulations are so high that multiple model runs become impossible. Conversely, simplistic models that treat denitrification as first-order decay process miss important controls on denitrification. We have proposed a Lagrangian framework of nonlinear reactive transport, in which the electron-donor supply by the aquifer matrix is parameterized by a relative reactivity, that is the reaction rate relative to a standard reaction rate for identical solute concentrations (Loschko et al., 2016). We could show that reactive transport simplifies to solving a single ordinary dfferential equation in terms of the cumulative relative reactivity for a given combination of inflow concentrations. Simulating 3-D flow and reactive transport are computationally so inexpensive that Monte Carlo simulation become feasible. The original scheme did not consider a change of the relative reactivity over time, implying that the electron-donor pool in the matrix is infinite. We have modified the scheme to address the consumption of the reducing aquifer constituents upon the reactions. We also analyzed how a minimally complex model of aerobic respiration and denitrification could look like. With the revised scheme, we performed Monte Carlo simulations in 3-D domains, confirming that the uncertainty in predicting nitrate breakthrough depends on the scale of observation. Reference: M. Loschko, T. Wöhling, D.L. Rudolph, O.A. Cirpka: Cumulative relative reactivity: a concept for modeling aquifer-scale reactive transport. Water Resour. Res. 52(10): 8117-8137, 2016, doi: 10.1002/2016WR019080.

Phase I Metabolic Stability and Electrophilic Reactivity of 2-Phenylaminophenylacetic Acid Derived Compounds.

PubMed

Pang, Yi Yun; Tan, Yee Min; Chan, Eric Chun Yong; Ho, Han Kiat

2016-07-18

Diclofenac and lumiracoxib are two highly analogous 2-phenylaminophenylacetic acid anti-inflammatory drugs exhibiting occasional dose-limiting hepatotoxicities. Prior data indicate that bioactivation and reactive metabolite formation play roles in the observed toxicity, but the exact chemical influence of the substituents remains elusive. In order to elucidate the role of chemical influence on metabolism related toxicity, metabolic stability and electrophilic reactivity were investigated for a series of structurally related analogues and their resulting metabolites. The resulting analogues embody progressive physiochemical changes through varying halogeno- and aliphatic substituents at two positions and were subjected to in vitro human liver microsomal metabolic stability and cell-based GSH depletion assays (to measure electrophilic reactivity). LC-MS/MS analysis of the GSH trapped reactive intermediates derived from the analogues was then used to identify the putative structures of reactive metabolites. We found that chemical modifications of the structural backbone led to noticeable perturbations of metabolic stability, electrophilic reactivity, and structures and composition of reactive metabolites. With the acquired data, the relationships between stability, reactivity, and toxicity were investigated in an attempt to correlate between Phase I metabolism and in vitro toxicity. A positive correlation was identified between reactivity and in vitro toxicity, indicating that electrophilic reactivity can be an indicator for in vitro toxicity. All in all, the effect of substituents on the structures and reactivity of the metabolites, however subtle the changes, should be taken into consideration during future drug design involving similar chemical features.

Team-Based Learning Practices and Principles in Comparison with Cooperative Learning and Problem-Based Learning

ERIC Educational Resources Information Center

Michaelsen, Larry K.; Davidson, Neil; Major, Claire Howell

2014-01-01

The authors address three questions: (1) What are the foundational practices of team-based learning (TBL)? (2) What are the fundamental principles underlying TBL's foundational practices? and (3) In what ways are TBL's foundational practices similar to and/or different from the practices employed by problem-based learning (PBL) and…

Using Web-Based Homework to Teach Principles of Microeconomics: A Preliminary Investigation

ERIC Educational Resources Information Center

Mitchell, Jeannette C.; Mitchell, Johanna E.

2017-01-01

This study evaluates an interactive web-based homework designed to increase student understanding in a principles of microeconomics course. Employing concepts from Action Research, the preliminary investigation was undertaken based on assumptions about the efficacy of online educational resources. Do students who do well on online homework improve…

Principle-Based Inferences in Preschoolers' Categorization of Novel Artifacts.

ERIC Educational Resources Information Center

Nelson, Deborah G. Kemler; And Others

Two parallel studies investigated the influence of principle-based and attribute-based similarity relations on new category learning by preschoolers. One of two possible functions of a single novel artifact (which differed between studies) was modeled for children and practiced by children. Children then judged which test objects received the same…

Leave islands as refugia for low-mobility species in managed forest mosaics

Treesearch

Stephanie J. Wessell-Kelly; Deanna H. Olson

2013-01-01

In recent years, forest management in the Pacifi c Northwest has shifted from one based largely on resource extraction to one based on ecosystem management principles. Forest management based on these principles involves simultaneously balancing and sustaining multiple forest resource values, including silvicultural, social, economic, and ecological objectives. Leave...

Using Participatory Action Research to Increase Learning Transfer of Recovery-Based Principles

ERIC Educational Resources Information Center

Barish, Diane J.

2009-01-01

This study questions whether or not participatory action research is an effective and practical method for increasing learning transfer of recovery-based principles. The participants (N = 250) were ethnically and educationally diverse clinicians, in an urban state mental health institute. The Self-Assessment of Recovery-Based Behaviors survey ( n…

A Study of the Program Management Responsibility Transfer Process for the F-16.

DTIC Science & Technology

1975-09-01

Guidance . . . ... 19 Subjective Criteria. .......... 21 Criteria Based on the Principles of Management ....... ........... ... 27 Planning...26 GSM/SM/75S-8 and then they will be fitted to the management structure of the two commands and IIQ USAF. Criteria Based on the Principles Of Management From...with each of these ýunc- tional areas with emphasis on some of the principles of management that are (in the writer’s opinion) important to the PMRT

Nucleophilic Addition of Reactive Dyes on Amidoximated Acrylic Fabrics

PubMed Central

El-Shishtawy, Reda M.; El-Zawahry, Manal M.; Abdelghaffar, Fatma; Ahmed, Nahed S. E.

2014-01-01

Seven reactive dyes judiciously selected based on chemical structures and fixation mechanisms were applied at 2% owf of shade on amidoximated acrylic fabrics. Amidoximated acrylic fabric has been obtained by a viable amidoximation process. The dyeability of these fabrics was evaluated with respect to the dye exhaustion, fixation, and colour strength under different conditions of temperature and dyeing time. Nucleophilic addition type reactive dyes show higher colour data compared to nucleophilic substitution ones. FTIR studies further implicate the binding of reactive dyes on these fabrics. A tentative mechanism is proposed to rationalize the high fixation yield obtained using nucleophilic addition type reactive dyes. Also, the levelling and fastness properties were evaluated for all dyes used. Excellent to good fastness and levelling properties were obtained for all samples irrespective of the dye used. The result of investigation offers a new method for a viable reactive dyeing of amidoximated acrylic fabrics. PMID:25258720

Electrical engineering unit for the reactive power control of the load bus at the voltage instability

NASA Astrophysics Data System (ADS)

Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.

2018-01-01

For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

Kinetic and mechanistic reactivity. Isoprene impact on ozone levels in an urban area near Tijuca Forest, Rio de Janeiro.

PubMed

da Silva, Cleyton Martins; da Silva, Luane Lima; Corrêa, Sergio Machado; Arbilla, Graciela

2016-12-01

Volatile organic compounds (VOCs) play a central role in atmospheric chemistry. In this work, the kinetic and mechanistic reactivities of VOCs are analyzed, and the contribution of the organic compounds emitted by anthropogenic and natural sources is estimated. VOCs react with hydroxyl radicals and other photochemical oxidants, such as ozone and nitrate radicals, which cause the conversion of NO to NO 2 in various potential reaction paths, including photolysis, to form oxygen atoms, which generate ozone. The kinetic reactivity was evaluated based on the reaction coefficients for hydroxyl radicals with VOCs. The mechanistic reactivity was estimated using a detailed mechanism and the incremental reactivity scale that Carter proposed. Different scenarios were proposed and discussed, and a minimum set of compounds, which may describe the tropospheric reactivity in the studied area, was determined. The role of isoprene was analyzed in terms of its contribution to ozone formation.

Behavioral reactivity to emotion challenge is associated with cortisol reactivity and regulation at 7, 15, and 24 months of age.

PubMed

Ursache, Alexandra; Blair, Clancy; Granger, Douglas A; Stifter, Cynthia; Voegtline, Kristin

2014-04-01

Emotionally arousing stimuli have been largely unsuccessful in eliciting cortisol responses in young children. Whether or not emotion challenge will elicit a cortisol response, however, may in part be determined by the extent to which the tasks elicit behavioral reactivity and regulation. We examined relations of behavioral reactivity and regulation to emotional arousal in the context of fear and frustration to the cortisol response at 7, 15, and 24 months of age in a low income, rural population based sample of 1,292 families followed longitudinally from birth. At each age, children participated in fear and frustration inducing tasks, and cortisol samples were taken at three time points (before the tasks began, 20 min following peak emotional arousal or after the series of tasks ended, and 40 min after peak arousal or the tasks ended) in order to capture both increases (reactivity) and subsequent decreases (regulation) in the cortisol response. Using multilevel models, we predicted the cortisol response from measures of behavioral reactivity and regulation. At 7 months of age, cortisol reactivity and recovery were related to behavioral reactivity during a frustration-eliciting task and marginally related to behavioral reactivity during a fear-eliciting task. At 15 and 24 months of age, however, cortisol reactivity and recovery were related only to behavioral reactivity during a fear-eliciting task. Results indicate that while behavioral reactivity is predictive of whether or not infants and young children will exhibit a cortisol response to emotionally arousing tasks, behavioral and cortisol reactivity are not necessarily coupled. © 2013 Wiley Periodicals, Inc.