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Sample records for mathematically reduced chemical

  1. Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

    SciTech Connect

    Ziaul Huque

    2007-08-31

    This is the final technical report for the project titled 'Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks'. The aim of the project was to develop an efficient chemistry model for combustion simulations. The reduced chemistry model was developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) was used via a new network topology known as Non-linear Principal Components Analysis (NPCA). A commonly used Multilayer Perceptron Neural Network (MLP-NN) was modified to implement NPCA-NN. The training rate of NPCA-NN was improved with the GEneralized Regression Neural Network (GRNN) based on kernel smoothing techniques. Kernel smoothing provides a simple way of finding structure in data set without the imposition of a parametric model. The trajectory data of the reaction mechanism was generated based on the optimization techniques of genetic algorithm (GA). The NPCA-NN algorithm was then used for the reduction of Dimethyl Ether (DME) mechanism. DME is a recently discovered fuel made from natural gas, (and other feedstock such as coal, biomass, and urban wastes) which can be used in compression ignition engines as a substitute for diesel. An in-house two-dimensional Computational Fluid Dynamics (CFD) code was developed based on Meshfree technique and time marching solution algorithm. The project also provided valuable research experience to two graduate students.

  2. Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

    SciTech Connect

    Nelson Butuk

    2005-12-01

    This is an annual technical report for the work done over the last year (period ending 9/30/2005) on the project titled ''Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks''. The aim of the project is to develop an efficient chemistry model for combustion simulations. The reduced chemistry model will be developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) will be used via a new network topology know as Non-linear Principal Components Analysis (NPCA). We report on the development of a novel procedure to speed up the training of NPCA. The same procedure termed L{sub 2}Boost can be used to increase the order of approximation of the Generalized Regression Neural Network (GRNN). It is pointed out that GRNN is a basic procedure for the emerging mesh free CFD. Also reported is an efficient simple approach of computing the derivatives of GRNN function approximation using complex variables or the Complex Step Method (CSM). The results presented demonstrate the significance of the methods developed and will be useful in many areas of applied science and engineering.

  3. Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

    SciTech Connect

    Nelson Butuk

    2004-12-01

    This is an annual technical report for the work done over the last year (period ending 9/30/2004) on the project titled ''Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks''. The aim of the project is to develop an efficient chemistry model for combustion simulations. The reduced chemistry model will be developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) will be used via a new network topology know as Non-linear Principal Components Analysis (NPCA). We report on the development of a procedure to speed up the training of NPCA. The developed procedure is based on the non-parametric statistical technique of kernel smoothing. When this smoothing technique is implemented as a Neural Network, It is know as Generalized Regression Neural Network (GRNN). We present results of implementing GRNN on a test problem. In addition, we present results of an in house developed 2-D CFD code that will be used through out the project period.

  4. Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

    SciTech Connect

    Nelson Butuk

    2006-09-21

    This is an annual technical report for the work done over the last year (period ending 9/30/2005) on the project titled ''Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks''. The aim of the project is to develop an efficient chemistry model for combustion simulations. The reduced chemistry model will be developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) will be used via a new network topology know as Non-linear Principal Components Analysis (NPCA). We report on the significant development made in developing a truly meshfree computational fluid dynamics (CFD) flow solver to be coupled to NPCA. First, the procedure of obtaining nearly analytic accurate first order derivatives using the complex step method (CSM) is extended to include computation of accurate meshfree second order derivatives via a theorem described in this report. Next, boosted generalized regression neural network (BGRNN), described in our previous report is combined with CSM and used to obtain complete solution of a hard to solve wave dominated sample second order partial differential equation (PDE): the cubic Schrodinger equation. The resulting algorithm is a significant improvement of the meshfree technique of smooth particle hydrodynamics method (SPH). It is suggested that the demonstrated meshfree technique be termed boosted smooth particle hydrodynamics method (BSPH). Some of the advantages of BSPH over other meshfree methods include; it is of higher order accuracy than SPH; compared to other meshfree methods, it is completely meshfree and does not require any background meshes; It does not involve any construction of shape function with their associated solution of possibly ill conditioned matrix equations; compared to some SPH techniques, no equation for the smoothing parameter is required; finally it is easy to program.

  5. Mathematical Modeling of Chemical Stoichiometry

    ERIC Educational Resources Information Center

    Croteau, Joshua; Fox, William P.; Varazo, Kristofoland

    2007-01-01

    In beginning chemistry classes, students are taught a variety of techniques for balancing chemical equations. The most common method is inspection. This paper addresses using a system of linear mathematical equations to solve for the stoichiometric coefficients. Many linear algebra books carry the standard balancing of chemical equations as an…

  6. Mathematical Modeling of Chemical Stoichiometry

    ERIC Educational Resources Information Center

    Croteau, Joshua; Fox, William P.; Varazo, Kristofoland

    2007-01-01

    In beginning chemistry classes, students are taught a variety of techniques for balancing chemical equations. The most common method is inspection. This paper addresses using a system of linear mathematical equations to solve for the stoichiometric coefficients. Many linear algebra books carry the standard balancing of chemical equations as an…

  7. Identification of Factors that Reduce Mathematics Anxiety of Preservice Elementary Teachers in Mathematics Content Courses

    ERIC Educational Resources Information Center

    Plaisance, DesLey Viator

    2007-01-01

    The purpose of this study was to identify factors that reduce mathematics anxiety in preservice elementary teachers enrolled in mathematics content courses. Students enrolled in ten sections of four different, required mathematics content courses in one specific semester were chosen as the population for this study. Approximately 180 students were…

  8. Some Chemical Applications of the 'New' Mathematics

    ERIC Educational Resources Information Center

    Mooney, Arthur

    1975-01-01

    Indicates how some branches of chemistry lend themselves to interpretation using a modern mathematical approach. Examples include set theory and the periodic table, matrix algebra and determinants and atomic theory, and symmetry and molecular structure. (GS)

  9. Some Chemical Applications of the 'New' Mathematics

    ERIC Educational Resources Information Center

    Mooney, Arthur

    1975-01-01

    Indicates how some branches of chemistry lend themselves to interpretation using a modern mathematical approach. Examples include set theory and the periodic table, matrix algebra and determinants and atomic theory, and symmetry and molecular structure. (GS)

  10. Mitigating the Mathematical Knowledge Gap between High School and First Year University Chemical Engineering Mathematics Course

    ERIC Educational Resources Information Center

    Basitere, Moses; Ivala, Eunice

    2015-01-01

    This paper reports on a study carried out at a University of Technology, South Africa, aimed at identifying the existence of the mathematical knowledge gap and evaluating the intervention designed to bridge the knowledge gap amongst students studying first year mathematics at the Chemical Engineering Extended Curriculum Program (ECP). In this…

  11. Some aspects of mathematical and chemical modeling of complex chemical processes

    NASA Technical Reports Server (NTRS)

    Nemes, I.; Botar, L.; Danoczy, E.; Vidoczy, T.; Gal, D.

    1983-01-01

    Some theoretical questions involved in the mathematical modeling of the kinetics of complex chemical process are discussed. The analysis is carried out for the homogeneous oxidation of ethylbenzene in the liquid phase. Particular attention is given to the determination of the general characteristics of chemical systems from an analysis of mathematical models developed on the basis of linear algebra.

  12. Dual photochemical replenisher system reduces chemical losses

    NASA Technical Reports Server (NTRS)

    Kolber, J. M.

    1967-01-01

    Dual replenisher system reduces chemical losses and maintains optimum solution concentration during long nonprocessing cycles of photo processing machines. Using a single 3-position switch and solenoid control valves, the system provides instantaneous flow control to each processing tank.

  13. Chemical Literacy Levels of Science and Mathematics Teacher Candidates

    ERIC Educational Resources Information Center

    Celik, Suat

    2014-01-01

    The goal of this study was to investigate Turkish science and mathematics teacher candidates' levels of attainment in chemical literacy. These candidates had all studied the new Turkish chemistry curriculum in high school. The sample of the study consisted of 112 students, who were first-year students in the Department of Secondary Science and…

  14. Reduced chemical kinetics for propane combustion

    NASA Technical Reports Server (NTRS)

    Ying, Shuh-Jing; Nguyen, Hung Lee

    1990-01-01

    It is pointed out that a detailed chemical kinetics mechanism for the combustion of propane consists of 40 chemical species and 118 elementary chemical reactions. An attempt is made to reduce the number of chemical species and elementary chemical reactions so that the computer run times and storage requirements may be greatly reduced in three-dimensional gas turbine combustion flow calculations, while maintaining accurate predictions of the propane combustion and exhaust emissions. By way of a sensitivity analysis, the species of interest and chemical reactions are classified in descending order of importance. Nineteen species are chosen, and their pressure, temperature, and concentration profiles are presented for the reduced mechanisms, which are then compared with those from the full 118 reactions. It is found that 45 reactions involving 27 species have to be kept for comparable agreement. A comparison of the results obtained from the 45 reactions to that of the full 118 shows that the pressure and temperature profiles and concentrations of C3H8, O2, N2, H2O, CO, and CO2 are within 10 percent of maximum change.

  15. Chemicals Reduce Need To Mow Grass

    NASA Technical Reports Server (NTRS)

    Humphrys, Brooks; Farley, Max; Gast, Larry J.

    1993-01-01

    Brief report discusses use of herbicides Roundup(R), Campaign(R), and Oust(R) to retard growth of Argentine bahia grass. Herbicide applied by use of spraying apparatus pulled by tractor. "Chemical mowing" keeps grass at "freshly mowed" height with less mechanical mowing. Applied to grass on shoulders of roads, reducing time spent on mowing.

  16. Chemicals Reduce Need To Mow Grass

    NASA Technical Reports Server (NTRS)

    Humphrys, Brooks; Farley, Max; Gast, Larry J.

    1993-01-01

    Brief report discusses use of herbicides Roundup(R), Campaign(R), and Oust(R) to retard growth of Argentine bahia grass. Herbicide applied by use of spraying apparatus pulled by tractor. "Chemical mowing" keeps grass at "freshly mowed" height with less mechanical mowing. Applied to grass on shoulders of roads, reducing time spent on mowing.

  17. 37 CFR 1.58 - Chemical and mathematical formulae and tables.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Chemical and mathematical... Provisions The Application § 1.58 Chemical and mathematical formulae and tables. (a) The specification, including the claims, may contain chemical and mathematical formulae, but shall not contain drawings or...

  18. Petri Nets - A Mathematical Formalism to Analyze Chemical Reaction Networks.

    PubMed

    Koch, Ina

    2010-12-17

    In this review we introduce and discuss Petri nets - a mathematical formalism to describe and analyze chemical reaction networks. Petri nets were developed to describe concurrency in general systems. We find most applications to technical and financial systems, but since about twenty years also in systems biology to model biochemical systems. This review aims to give a short informal introduction to the basic formalism illustrated by a chemical example, and to discuss possible applications to the analysis of chemical reaction networks, including cheminformatics. We give a short overview about qualitative as well as quantitative modeling Petri net techniques useful in systems biology, summarizing the state-of-the-art in that field and providing the main literature references. Finally, we discuss advantages and limitations of Petri nets and give an outlook to further development.

  19. Reduced graphene oxide by chemical graphitization.

    PubMed

    Moon, In Kyu; Lee, Junghyun; Ruoff, Rodney S; Lee, Hyoyoung

    2010-09-21

    Reduced graphene oxides (RG-Os) have attracted considerable interest, given their potential applications in electronic and optoelectronic devices and circuits. However, very little is known regarding the chemically induced reduction method of graphene oxide (G-O) in both solution and gas phases, with the exception of the hydrazine-reducing agent, even though it is essential to use the vapour phase for the patterning of hydrophilic G-Os on prepatterned substrates and in situ reduction to hydrophobic RG-Os. In this paper, we report a novel reducing agent system (hydriodic acid with acetic acid (HI-AcOH)) that allows for an efficient, one-pot reduction of a solution-phased RG-O powder and vapour-phased RG-O (VRG-O) paper and thin film. The reducing agent system provided highly qualified RG-Os by mass production, resulting in highly conducting RG-O(HI-AcOH). Moreover, VRG-O(HI-AcOH) paper and thin films were prepared at low temperatures (40 °C) and were found to be applicable to flexible devices. This one-pot method is expected to advance research on highly conducting graphene platelets.

  20. Chemical, mechanical treatment options reduce hydroprocessor fouling

    SciTech Connect

    Groce, B.C.

    1996-01-29

    The processing of opportunity crudes and the need to meet stricter environmental regulations in the production of distillates and finished fuels have increased the benefit of the hydroprocessing unit to the refiner. With this potential for increased margins and more environmentally friendly fuel products comes increased risk of fouling in hydroprocessing units. Increased fouling can reduce unit reliability and increase maintenance and operating costs. The refiner has several options available to help minimize the fouling and maximize the unit`s profitability and flexibility. One of the two commonly selected options is to allocate capital for a mechanical solution to address a specific cause of fouling. The other option is the use of a chemical treatment program. This paper reviews the efficiency and implementation procedures for these two processes.

  1. Mathematical modeling of physical-chemical wastewater treatment plant

    SciTech Connect

    Torruellas, E.D.

    1987-01-01

    The scheme of treatment modeled includes processes such as coagulation, flocculation, sedimentation, sand filtration, adsorption on granular activated carbon, and surge storage. Sludge treatment processes such as gravity thickening, vacuum filter dewatering, and hauling and disposal were also simulated. The primary objective of this work is to demonstrate that an optimization scheme can be used to determine the minimum total cost of a complex physical-chemical treatment system with models representing the individual unit processes. A method for determining the minimum cost design of a physical-chemical treatment plant is presented. The method utilizes an existing search technique (Box complex algorithm) to optimize a non-linear cost function for the physical-chemical processes. Thus, the physical-chemical treatment plant design is formulated as an optimization problem with non-linear cost functions and realistic mathematical models for each of its constituent unit processes. The level of cost resolution adopted derives from a series of economic models developed which basically make a Present Worth Analysis of each unit within the system. The economic data are based mostly on updated cost information obtained from Environmental Protection Agency Technology Transfer Manuals. Among the benefits directly derived from this study are the following: optimum economic design and operation of a typical physical-chemical treatment plant, simplified and directly oriented pilot plant studies, and the cost savings associated with it. Also, the formulation of a relatively new design concept is developed which underlines the need of the simultaneous consideration of all the components of a physical-chemical treatment plant for the most economic design.

  2. Assessing chromate reduction by dissimilatory iron reducing bacteria using mathematical modeling.

    PubMed

    Peng, Lai; Liu, Yiwen; Gao, Shu-Hong; Dai, Xiaohu; Ni, Bing-Jie

    2015-11-01

    Chromate (Cr (VI)) is a ubiquitous contaminant in aquifers and soils, which can be reduced to its trivalent counterpart (Cr (III)), with the hazard being relieved. The coupling microbial and chemical reduction by dissimilatory iron reducing bacteria (IRB) is a promising approach for the reduction of Cr (VI) to Cr (III). In this work, three mathematical models with different Cr (VI) reduction pathways were proposed and compared based on their ability to predict the performance of an IRB-based stirred-flow reactor treating Cr (VI) contaminated medium and to provide insights into the possible chemical or microbial pathways for Cr (VI) reduction in the system. The Cr (VI) reduction was considered as chemical reaction between Fe (II) and Cr (VI), direct microbial reduction by IRB and combined biotic-abiotic reduction in these three models, respectively. Model evaluation results indicated that the model incorporating both chemical and microbial Cr (VI) reductions could well describe the system performance. In contrast, the other two single-pathway models were not capable of predicting the experimental data, suggesting that both chemical and microbial pathways contributed to Cr (VI) reduction by IRB. The validity of the two-pathway model was further confirmed by an independent experimental data set with different conditions. The results further revealed that the organic carbon availability and Cr (VI) loading rates for the IRB in the system determined the relative contributions of chemical and microbial pathways to overall Cr (VI) reduction.

  3. Mathematical correction for fingerprint similarity measures to improve chemical retrieval.

    PubMed

    Swamidass, S Joshua; Baldi, Pierre

    2007-01-01

    In many modern chemoinformatics systems, molecules are represented by long binary fingerprint vectors recording the presence or absence of particular features or substructures, such as labeled paths or trees, in the molecular graphs. These long fingerprints are often compressed to much shorter fingerprints using a simple modulo operation. As the length of the fingerprints decreases, their typical density and overlap tend to increase, and so does any similarity measure based on overlap, such as the widely used Tanimoto similarity. Here we show that this correlation between shorter fingerprints and higher similarity can be thought of as a systematic error introduced by the fingerprint folding algorithm and that this systematic error can be corrected mathematically. More precisely, given two molecules and their compressed fingerprints of a given length, we show how a better estimate of their uncompressed overlap, hence of their similarity, can be derived to correct for this bias. We show how the correction can be implemented not only for the Tanimoto measure but also for all other commonly used measures. Experiments on various data sets and fingerprint sizes demonstrate how, with a negligible computational overhead, the correction noticeably improves the sensitivity and specificity of chemical retrieval.

  4. Reducible or irreducible? Mathematical reasoning and the ontological method.

    PubMed

    Fisher, William P

    2010-01-01

    Science is often described as nothing but the practice of measurement. This perspective follows from longstanding respect for the roles mathematics and quantification have played as media through which alternative hypotheses are evaluated and experience becomes better managed. Many figures in the history of science and psychology have contributed to what has been called the "quantitative imperative," the demand that fields of study employ number and mathematics even when they do not constitute the language in which investigators think together. But what makes an area of study scientific is, of course, not the mere use of number, but communities of investigators who share common mathematical languages for exchanging quantitative and quantitative value. Such languages require rigorous theoretical underpinning, a basis in data sufficient to the task, and instruments traceable to reference standard quantitative metrics. The values shared and exchanged by such communities typically involve the application of mathematical models that specify the sufficient and invariant relationships necessary for rigorous theorizing and instrument equating. The mathematical metaphysics of science are explored with the aim of connecting principles of quantitative measurement with the structures of sufficient reason.

  5. Thermal properties of graphite oxide, thermally reduced graphene and chemically reduced graphene

    NASA Astrophysics Data System (ADS)

    Jankovský, Ondřej; Sedmidubský, David; Lojka, Michal; Sofer, Zdeněk

    2017-07-01

    We compared thermal behavior and other properties of graphite oxide, thermally reduced graphene and chemically reduced graphene. Graphite was oxidized according to the Hofmann method using potassium chlorate as oxidizing agent in strongly acidic environment. In the next step, the formed graphite oxide was chemically or thermally reduced yielding graphene. The mechanism of thermal reduction was studied using STA-MS. Graphite oxide and both thermally and chemically reduced graphenes were analysed by SEM, EDS, elemental combustion analysis, XPS, Raman spectroscopy, XRD and BET. These findings will help for the large scale production of graphene with appropriate chemical composition.

  6. Mathematical Formalism of Nonequilibrium Thermodynamics for Nonlinear Chemical Reaction Systems with General Rate Law

    NASA Astrophysics Data System (ADS)

    Ge, Hao; Qian, Hong

    2017-01-01

    This paper studies a mathematical formalism of nonequilibrium thermodynamics for chemical reaction models with N species, M reactions, and general rate law. We establish a mathematical basis for J. W. Gibbs' macroscopic chemical thermodynamics under G. N. Lewis' kinetic law of entire equilibrium (detailed balance in nonlinear chemical kinetics). In doing so, the equilibrium thermodynamics is then naturally generalized to nonequilibrium settings without detailed balance. The kinetic models are represented by a Markovian jumping process. A generalized macroscopic chemical free energy function and its associated balance equation with nonnegative source and sink are the major discoveries. The proof is based on the large deviation principle of this type of Markov processes. A general fluctuation dissipation theorem for stochastic reaction kinetics is also proved. The mathematical theory illustrates how a novel macroscopic dynamic law can emerges from the mesoscopic kinetics in a multi-scale system.

  7. The Physical Meaning of the Mathematical Formalism Present In Limiting Chemical Equations; or, How Dilute Is Dilute?

    ERIC Educational Resources Information Center

    Contreras-Ortega, C.; Bustamante, N.; Guevara, J. L.; Portillo, C.; Kesternich, V.

    2007-01-01

    A general mathematical treatment for chemical systems is described that might help students to better understand the real scope of the mathematical equations. The extent to which an equation acceptably describes a chemical system is determined from the limiting values of practical chemical variables and the concordance value defined by given…

  8. The Physical Meaning of the Mathematical Formalism Present In Limiting Chemical Equations; or, How Dilute Is Dilute?

    ERIC Educational Resources Information Center

    Contreras-Ortega, C.; Bustamante, N.; Guevara, J. L.; Portillo, C.; Kesternich, V.

    2007-01-01

    A general mathematical treatment for chemical systems is described that might help students to better understand the real scope of the mathematical equations. The extent to which an equation acceptably describes a chemical system is determined from the limiting values of practical chemical variables and the concordance value defined by given…

  9. A mathematical model for material removal and chemical mechanical synergy in chemical mechanical polishing at molecular scale

    NASA Astrophysics Data System (ADS)

    Bai, J.; Zhao, Y. W.; Wang, Y. G.

    2007-08-01

    This paper presents a mathematical material removal model based on the chemical and mechanical synergistic effects in the chemical-mechanical polishing (CMP) process. It seems to explain the transition from a chemically dominant region to a mechanically dominant region. In addition, this model predicts the effects of most variables involved in the CMP process including the processing conditions (velocity, downpressure), pad properties (modulus, hardness and asperity sizes) and slurry characteristics (particle size, concentration and distribution). The results reveal some insights into the micro-contact and wear mechanisms of the CMP process.

  10. Mesoscopic kinetic basis of macroscopic chemical thermodynamics: A mathematical theory.

    PubMed

    Ge, Hao; Qian, Hong

    2016-11-01

    Gibbs' macroscopic chemical thermodynamics is one of the most important theories in chemistry. Generalizing it to mesoscaled nonequilibrium systems is essential to biophysics. The nonequilibrium stochastic thermodynamics of chemical reaction kinetics suggested a free energy balance equation dF^{(meso)}/dt=E_{in}-e_{p} in which the free energy input rate E_{in} and dissipation rate e_{p} are both non-negative, and E_{in}≤e_{p}. We prove that in the macroscopic limit by merely allowing the molecular numbers to be infinite, the generalized mesoscopic free energy F^{(meso)} converges to φ^{ss}, the large deviation rate function for the stationary distributions. This generalized macroscopic free energy φ^{ss} now satisfies a balance equation dφ^{ss}(x)/dt=cmf(x)-σ(x), in which x represents chemical concentration. The chemical motive force cmf(x) and entropy production rate σ(x) are both non-negative, and cmf(x)≤σ(x). The balance equation is valid generally in isothermal driven systems and is different from mechanical energy conservation and the first law; it is actually an unknown form of the second law. Consequences of the emergent thermodynamic quantities and equalities are further discussed. The emergent "law" is independent of underlying kinetic details. Our theory provides an example showing how a macroscopic law emerges from a level below.

  11. Mesoscopic kinetic basis of macroscopic chemical thermodynamics: A mathematical theory

    NASA Astrophysics Data System (ADS)

    Ge, Hao; Qian, Hong

    2016-11-01

    Gibbs' macroscopic chemical thermodynamics is one of the most important theories in chemistry. Generalizing it to mesoscaled nonequilibrium systems is essential to biophysics. The nonequilibrium stochastic thermodynamics of chemical reaction kinetics suggested a free energy balance equation d F(meso)/d t =Ein-ep in which the free energy input rate Ein and dissipation rate ep are both non-negative, and Ein≤ep . We prove that in the macroscopic limit by merely allowing the molecular numbers to be infinite, the generalized mesoscopic free energy F(meso) converges to φss, the large deviation rate function for the stationary distributions. This generalized macroscopic free energy φss now satisfies a balance equation d φss(x ) /d t =cmf(x ) -σ (x ) , in which x represents chemical concentration. The chemical motive force cmf(x ) and entropy production rate σ (x ) are both non-negative, and cmf(x )≤σ (x ) . The balance equation is valid generally in isothermal driven systems and is different from mechanical energy conservation and the first law; it is actually an unknown form of the second law. Consequences of the emergent thermodynamic quantities and equalities are further discussed. The emergent "law" is independent of underlying kinetic details. Our theory provides an example showing how a macroscopic law emerges from a level below.

  12. Reducing chemical exposures at home: opportunities for action.

    PubMed

    Zota, Ami R; Singla, Veena; Adamkiewicz, Gary; Mitro, Susanna D; Dodson, Robin E

    2017-07-29

    Indoor environments can influence human environmental chemical exposures and, ultimately, public health. Furniture, electronics, personal care and cleaning products, floor coverings and other consumer products contain chemicals that can end up in the indoor air and settled dust. Consumer product chemicals such as phthalates, phenols, flame retardants and per- and polyfluorinated alkyl substances are widely detected in the US general population, including vulnerable populations, and are associated with adverse health effects such as reproductive and endocrine toxicity. We discuss the implications of our recent meta-analysis describing the patterns of chemical exposures and the ubiquity of multiple chemicals in indoor environments. To reduce the likelihood of exposures to these toxic chemicals, we then discuss approaches for exposure mitigation: targeting individual behaviour change, household maintenance and purchasing decisions, consumer advocacy and corporate responsibility in consumer markets, and regulatory action via state/federal policies. There is a need to further develop evidence-based strategies for chemical exposure reduction in each of these areas, given the multi-factorial nature of the problem. Further identifying those at greatest risk; understanding the individual, household and community factors that influence indoor chemical exposures; and developing options for mitigation may substantially improve individuals' exposures and health. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. Reducing Sexual Violence by Increasing the Supply of Toilets in Khayelitsha, South Africa: A Mathematical Model

    PubMed Central

    Gonsalves, Gregg S.; Kaplan, Edward H.; Paltiel, A. David

    2015-01-01

    Background Sexual violence is a major public health issue, affecting 35% of women worldwide. Major risk factors for sexual assault include inadequate indoor sanitation and the need to travel to outdoor toilet facilities. We estimated how increasing the number of toilets in an urban township (Khayelitsha, South Africa) might reduce both economic costs and the incidence and social burden of sexual assault. Methods We developed a mathematical model that links risk of sexual assault to the number of sanitation facilities and the time a woman must spend walking to a toilet. We defined a composite societal cost function, comprising both the burden of sexual assault and the costs of installing and maintaining public chemical toilets. By expressing total social costs as a function of the number of available toilets, we were able to identify an optimal (i.e., cost-minimizing) social investment in toilet facilities. Findings There are currently an estimated 5600 toilets in Khayelitsha. This results in 635 sexual assaults and US$40 million in combined social costs each year. Increasing the number of toilets to 11300 would minimize total costs ($35 million) and reduce sexual assaults to 446. Higher toilet installation and maintenance costs would be more than offset by lower sexual assault costs. Probabilistic sensitivity analysis shows that the optimal number of toilets exceeds the original allocation of toilets in the township in over 80% of the 5000 iterations of the model. Interpretation Improving access to sanitation facilities in urban settlements will simultaneously reduce the incidence of sexual assaults and overall cost to society. Since our analysis ignores the many additional health benefits of improving sanitation in resource-constrained urban areas (e.g., potential reductions in waterborne infectious diseases), the optimal number of toilets identified here should be interpreted as conservative. PMID:25923105

  14. Reducing sexual violence by increasing the supply of toilets in Khayelitsha, South Africa: a mathematical model.

    PubMed

    Gonsalves, Gregg S; Kaplan, Edward H; Paltiel, A David

    2015-01-01

    Sexual violence is a major public health issue, affecting 35% of women worldwide. Major risk factors for sexual assault include inadequate indoor sanitation and the need to travel to outdoor toilet facilities. We estimated how increasing the number of toilets in an urban township (Khayelitsha, South Africa) might reduce both economic costs and the incidence and social burden of sexual assault. We developed a mathematical model that links risk of sexual assault to the number of sanitation facilities and the time a woman must spend walking to a toilet. We defined a composite societal cost function, comprising both the burden of sexual assault and the costs of installing and maintaining public chemical toilets. By expressing total social costs as a function of the number of available toilets, we were able to identify an optimal (i.e., cost-minimizing) social investment in toilet facilities. There are currently an estimated 5600 toilets in Khayelitsha. This results in 635 sexual assaults and US$40 million in combined social costs each year. Increasing the number of toilets to 11300 would minimize total costs ($35 million) and reduce sexual assaults to 446. Higher toilet installation and maintenance costs would be more than offset by lower sexual assault costs. Probabilistic sensitivity analysis shows that the optimal number of toilets exceeds the original allocation of toilets in the township in over 80% of the 5000 iterations of the model. Improving access to sanitation facilities in urban settlements will simultaneously reduce the incidence of sexual assaults and overall cost to society. Since our analysis ignores the many additional health benefits of improving sanitation in resource-constrained urban areas (e.g., potential reductions in waterborne infectious diseases), the optimal number of toilets identified here should be interpreted as conservative.

  15. Quantification of chemically reducing species in the phosphate ion catalyzed degradation of reducing sugars.

    PubMed

    Rizzi, George P; Amba, Eme E; Heineman, William R

    2010-09-08

    Chemically reducing species formed during phosphate ion catalyzed degradation of reducing sugars were directly quantified by titration with 2,6-dichloroindophenol (Tillman's reagent) and by measurement of open circuit electrical redox potentials. Both techniques demonstrated a time-dependent increased production of chemically reducing species in 0.1 M phosphate buffer at 100 degrees C and the increasingly negative redox potentials observed were consistent with the formation of reductones. Cyclic voltammetry (CV) was investigated in an attempt to generate and observe the sugar-derived highly reactive reducing species in situ. CV analysis of a model Amadori compound, N-(1-deoxyfructos-1-yl)piperidine, indicated oxidative waves consistent with reductone formation, but chemical instability of the oxidation products formed precluded the electrochemical detection of highly electrophilic reducing species such as reductones.

  16. Chemically reduced graphene oxide for ammonia detection at room temperature.

    PubMed

    Ghosh, Ruma; Midya, Anupam; Santra, Sumita; Ray, Samit K; Guha, Prasanta K

    2013-08-14

    Chemically reduced graphene oxide (RGO) has recently attracted growing interest in the area of chemical sensors because of its high electrical conductivity and chemically active defect sites. This paper reports the synthesis of chemically reduced GO using NaBH4 and its performance for ammonia detection at room temperature. The sensing layer was synthesized on a ceramic substrate containing platinum electrodes. The effect of the reduction time of graphene oxide (GO) was explored to optimize the response, recovery, and response time. The RGO film was characterized electrically and also with atomic force microscopy and X-ray photoelectron spectroscopy. The sensor response was found to lie between 5.5% at 200 ppm (parts per million) and 23% at 2800 ppm of ammonia, and also resistance recovered quickly without any application of heat (for lower concentrations of ammonia). The sensor was exposed to different vapors and found to be selective toward ammonia. We believe such chemically reduced GO could potentially be used to manufacture a new generation of low-power portable ammonia sensors.

  17. Chemical and mathematical modeling of asphaltene reaction pathways

    SciTech Connect

    Salvage, P.E.

    1986-01-01

    Precipitated asphaltene was subjected to pyrolysis and hydropyrolysis, both neat and in solvents, and catalytic hydroprocessing. A solvent extraction procedure defined gas, maltene, asphaltene, and coke product fractions. The apparent first order rate constant for asphaltene conversion at 400/sup 0/C was relatively insensitive to the particular reaction scheme. The yield of gases likewise showed little variation and was always less than 10%. On the other hand, the maltene and coke yields were about 20% and 60%, respectively, from neat pyrolysis, and about 60% and less than 5%, respectively, from catalytic reactions. The temporal variations of the product fractions allowed discernment of asphaltene reaction pathways. The primary reaction of asphaltene was to residual asphaltene, maltenes, and gases. The residual asphaltene reacted thermally to coke and catalytically to maltenes at the expense of coke. Secondary degradation of these primary products led to lighter compounds. Reaction mechanism for pyrolysis of asphaltene model compounds and alkylaromstics were determined. The model compound kinetics results were combined with a stochastic description of asphaltene structure in a mathematical model of asphaltene pyrolysis. Individual molecular product were assigned to either the gas, maltene, asphaltene, or coke product fractions, and summation of the weights of each constituted the model's predictions. The temporal variation of the product fractions from simulated asphaltene pyrolysis compared favorably with experimental results.

  18. Mathematical relationships between metrics of chemical bioaccumulation in fish.

    PubMed

    Mackay, Don; Arnot, Jon A; Gobas, Frank A P C; Powell, David E

    2013-07-01

    Five widely used metrics of bioaccumulation in fish are defined and discussed, namely the octanol-water partition coefficient (KOW ), bioconcentration factor (BCF), bioaccumulation factor (BAF), biomagnification factor (BMF), and trophic magnification factor (TMF). Algebraic relationships between these metrics are developed and discussed using conventional expressions for chemical uptake from water and food and first-order losses by respiration, egestion, biotransformation, and growth dilution. Two BCFs may be defined, namely as an equilibrium partition coefficient KFW or as a nonequilibrium BCFK in which egestion losses are included. Bioaccumulation factors are shown to be the product of the BCFK and a novel equilibrium multiplier M containing 2 ratios, namely, the diet-to-water concentration ratio and the ratio of uptake rate constants for respiration and dietary uptake. Biomagnification factors are shown to be proportional to the lipid-normalized ratio of the predator/prey values of BCFK and the ratio of the equilibrium multipliers. Relationships with TMFs are also discussed. The effects of chemical hydrophobicity, biotransformation, and growth are evaluated by applying the relationships to a range of illustrative chemicals of varying KOW in a linear 4-trophic-level food web with typical values for uptake and loss rate constants. The roles of respiratory and dietary intakes are demonstrated, and even slow rates of biotransformation and growth can significantly affect bioaccumulation. The BCFK s and the values of M can be regarded as the fundamental determinants of bioaccumulation and biomagnification in aquatic food webs. Analyzing data from food webs can be enhanced by plotting logarithmic lipid-normalized concentrations or fugacities as a linear function of trophic level to deduce TMFs. Implications for determining bioaccumulation by laboratory tests for regulatory purposes are discussed.

  19. 37 CFR 1.58 - Chemical and mathematical formulae and tables.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...)) must maintain the spatial relationships (e.g., alignment of columns and rows) of the table elements... formulae and tables. 1.58 Section 1.58 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND... Provisions The Application § 1.58 Chemical and mathematical formulae and tables. (a) The...

  20. 37 CFR 1.58 - Chemical and mathematical formulae and tables.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (e.g., alignment of columns and rows) of the table elements when displayed so as to visually preserve... formulae and tables. 1.58 Section 1.58 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND... Provisions The Application § 1.58 Chemical and mathematical formulae and tables. (a) The...

  1. 37 CFR 1.58 - Chemical and mathematical formulae and tables.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...)) must maintain the spatial relationships (e.g., alignment of columns and rows) of the table elements... formulae and tables. 1.58 Section 1.58 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND... Provisions The Application § 1.58 Chemical and mathematical formulae and tables. (a) The...

  2. 37 CFR 1.58 - Chemical and mathematical formulae and tables.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...)) must maintain the spatial relationships (e.g., alignment of columns and rows) of the table elements... formulae and tables. 1.58 Section 1.58 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND... Provisions The Application § 1.58 Chemical and mathematical formulae and tables. (a) The...

  3. Mathematical description of complex chemical kinetics and application to CFD modeling codes

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1993-01-01

    A major effort in combustion research at the present time is devoted to the theoretical modeling of practical combustion systems. These include turbojet and ramjet air-breathing engines as well as ground-based gas-turbine power generating systems. The ability to use computational modeling extensively in designing these products not only saves time and money, but also helps designers meet the quite rigorous environmental standards that have been imposed on all combustion devices. The goal is to combine the very complex solution of the Navier-Stokes flow equations with realistic turbulence and heat-release models into a single computer code. Such a computational fluid-dynamic (CFD) code simulates the coupling of fluid mechanics with the chemistry of combustion to describe the practical devices. This paper will focus on the task of developing a simplified chemical model which can predict realistic heat-release rates as well as species composition profiles, and is also computationally rapid. We first discuss the mathematical techniques used to describe a complex, multistep fuel oxidation chemical reaction and develop a detailed mechanism for the process. We then show how this mechanism may be reduced and simplified to give an approximate model which adequately predicts heat release rates and a limited number of species composition profiles, but is computationally much faster than the original one. Only such a model can be incorporated into a CFD code without adding significantly to long computation times. Finally, we present some of the recent advances in the development of these simplified chemical mechanisms.

  4. Mathematical Description of Complex Chemical Kinetics and Application to CFD Modeling Codes

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1993-01-01

    A major effort in combustion research at the present time is devoted to the theoretical modeling of practical combustion systems. These include turbojet and ramjet air-breathing engines as well as ground-based gas-turbine power generating systems. The ability to use computational modeling extensively in designing these products not only saves time and money, but also helps designers meet the quite rigorous environmental standards that have been imposed on all combustion devices. The goal is to combine the very complex solution of the Navier-Stokes flow equations with realistic turbulence and heat-release models into a single computer code. Such a computational fluid-dynamic (CFD) code simulates the coupling of fluid mechanics with the chemistry of combustion to describe the practical devices. This paper will focus on the task of developing a simplified chemical model which can predict realistic heat-release rates as well as species composition profiles, and is also computationally rapid. We first discuss the mathematical techniques used to describe a complex, multistep fuel oxidation chemical reaction and develop a detailed mechanism for the process. We then show how this mechanism may be reduced and simplified to give an approximate model which adequately predicts heat release rates and a limited number of species composition profiles, but is computationally much faster than the original one. Only such a model can be incorporated into a CFD code without adding significantly to long computation times. Finally, we present some of the recent advances in the development of these simplified chemical mechanisms.

  5. Mathematical description of complex chemical kinetics and application to CFD modeling codes

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1993-01-01

    A major effort in combustion research at the present time is devoted to the theoretical modeling of practical combustion systems. These include turbojet and ramjet air-breathing engines as well as ground-based gas-turbine power generating systems. The ability to use computational modeling extensively in designing these products not only saves time and money, but also helps designers meet the quite rigorous environmental standards that have been imposed on all combustion devices. The goal is to combine the very complex solution of the Navier-Stokes flow equations with realistic turbulence and heat-release models into a single computer code. Such a computational fluid-dynamic (CFD) code simulates the coupling of fluid mechanics with the chemistry of combustion to describe the practical devices. This paper will focus on the task of developing a simplified chemical model which can predict realistic heat-release rates as well as species composition profiles, and is also computationally rapid. We first discuss the mathematical techniques used to describe a complex, multistep fuel oxidation chemical reaction and develop a detailed mechanism for the process. We then show how this mechanism may be reduced and simplified to give an approximate model which adequately predicts heat release rates and a limited number of species composition profiles, but is computationally much faster than the original one. Only such a model can be incorporated into a CFD code without adding significantly to long computation times. Finally, we present some of the recent advances in the development of these simplified chemical mechanisms.

  6. Chemical Analysis of NOx Removal Under Different Reduced Electric Fields

    NASA Astrophysics Data System (ADS)

    Haddouche, A.; Lemerini, M.

    2015-07-01

    This work presents a chemical kinetic analysis of different species involved in nitrogen-oxygen mixed gas induced by stationary corona discharge at room temperature and atmospheric pressure. This study takes into account twenty different chemical species participating in one hundred and seventy selected chemical reactions. The reaction rate coefficients are taken from the literature, and the density is analyzed by the continuity equation without the diffusion term. A large number of investigations considered the removal of NOx showing the effects of N, O and O3 radicals. The aim of the present simulation is to complete these studies by analysing various plasma species under different reduced electric fields in the range of 100-200 Td (1 Td=10-21 V·m2). In particular, we analyze the time evolution of depopulation (10-9-10-3 s) of NOx. We have found that the depopulation rate of NO and NO2 is substantially affected by the rise of reduced electric field as it grows from 100 Td to 200 Td. This allows us to ascertain the important role played by the reduced electric field.

  7. Mathematical Model of Load Pass and Prediction of Fatigue Life on Bolt Threads with Reduced Lead

    NASA Astrophysics Data System (ADS)

    Asayama, Yukiteru

    A mathematical model is proposed in order to elucidate the mechanism that the fatigue strength of external threads increases by reducing the lead on a thread system such as a bolt and nut. The model is constructed from the concept that a local strain proportional to the reducing degree of the lead, although the local strain is at first produced in the bolt thread farthest from the bearing surface of the nut, is induced in each thread root with an increase of applied load. The fatigue life predicted from the mathematical model shows good agreement with the experimental fatigue life of cadmium-plated external threads with the reduced lead on the material having strength as high as 1270MPa. The model can provide useful suggestions for the design of fasteners for aerospace, which are required to satisfy severe requirements of fatigue strengths and dimensions.

  8. The Normalized Reduced Form and Cell Mathematical Tools for Lattice Analysis—Symmetry and Similarity

    PubMed Central

    Mighell, Alan D.

    2003-01-01

    To intelligently and effectively use crystallographic databases, mathematical and computer tools are required that can elucidate diverse types of intra- and interlattice relationships. Two such tools are the normalized reduced form and normalized reduced cell. Practical experience has revealed that the first tool—the normalized reduced form—is very helpful in establishing lattice metric symmetry as it enables one to readily deduce significant relationships between the elements of the reduced form. Likewise research with crystallographic databases has demonstrated that the second tool—the normalized reduced cell—plays a vital role in determining metrically similar lattices. Knowledge of similar lattices has practical value in solving structures, in assignment of structure types, in materials design, and in nano-technology. In addition to using the reduced cell, it is recommended that lattice-matching strategies based on the normalized reduced cell be routinely carried out in database searching, in data evaluation, and in experimental work. PMID:27413622

  9. The Normalized Reduced Form and Cell Mathematical Tools for Lattice Analysis-Symmetry and Similarity.

    PubMed

    Mighell, Alan D

    2003-01-01

    To intelligently and effectively use crystallographic databases, mathematical and computer tools are required that can elucidate diverse types of intra- and interlattice relationships. Two such tools are the normalized reduced form and normalized reduced cell. Practical experience has revealed that the first tool-the normalized reduced form-is very helpful in establishing lattice metric symmetry as it enables one to readily deduce significant relationships between the elements of the reduced form. Likewise research with crystallographic databases has demonstrated that the second tool-the normalized reduced cell-plays a vital role in determining metrically similar lattices. Knowledge of similar lattices has practical value in solving structures, in assignment of structure types, in materials design, and in nano-technology. In addition to using the reduced cell, it is recommended that lattice-matching strategies based on the normalized reduced cell be routinely carried out in database searching, in data evaluation, and in experimental work.

  10. A mathematical model and simulation results of plasma enhanced chemical vapor deposition of silicon nitride films

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a mathematical model of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride thin films from SiH4-NH3-N2-Ar mixture, an important application in modern materials science. Our multiphysics model describes gas dynamics, chemical physics, plasma physics and electrodynamics. The PECVD technology is inherently multiscale, from macroscale processes in the chemical reactor to atomic-scale surface chemistry. Our macroscale model is based on Navier-Stokes equations for a transient laminar flow of a compressible chemically reacting gas mixture, together with the mass transfer and energy balance equations, Poisson equation for electric potential, electrons and ions balance equations. The chemical kinetics model includes 24 species and 58 reactions: 37 in the gas phase and 21 on the surface. A deposition model consists of three stages: adsorption to the surface, diffusion along the surface and embedding of products into the substrate. A new model has been validated on experimental results obtained with the "Plasmalab System 100" reactor. We present the mathematical model and simulation results investigating the influence of flow rate and source gas proportion on silicon nitride film growth rate and chemical composition.

  11. Mathematical Modeling of Chemical Vapor Deposition of Material on a Curvilinear Surface

    NASA Astrophysics Data System (ADS)

    Kuvyrkin, G. N.; Zhuravskii, A. V.; Savel‧eva, I. Yu.

    2016-11-01

    In this work, a mathematical model has been constructed that describes the process of chemical vapor deposition of material on a curvilinear plate. On the boundary where the deposition occurs, account is taken of convective heat transfer, heat transfer by radiation, and heat and mass transfer during the attachment of the substance to the surface. A numerical algorithm is proposed for finding the temperature profile at any instant of time; results and an analysis of numerical calculation are given for different materials.

  12. A mathematical model for the transport and fate of organic chemicals in unsaturated/saturated soils.

    PubMed Central

    Lindstrom, F T; Piver, W T

    1985-01-01

    A mathematical model, simulating the transport and fate of nonionizable organic compounds in unsaturated/saturated porous media (soils) in a terrestrial microcosm has been developed. Using the principles of water mass, momentum, heat energy and chemical mass balance, the three fields: moisture, temperature, and liquid phase chemical concentration are solved for simultaneously by coupling the soil slab to an environmentally realistic air-soil interface (a dynamic free boundary) conditions and a prescribed height water table. The environmental conditions at the soil surface-air chamber interface are easily changed, via geometric scaling factors, to simulate either an open agricultural field or a landfill type of situation. Illustrative simulation runs examine the effects of different soil-chemical characteristics on hydrological and chemical concentration profiles. PMID:4029096

  13. Reduced hazard chemicals for solid rocket motor production

    NASA Technical Reports Server (NTRS)

    Caddy, Larry A.; Bowman, Ross; Richards, Rex A.

    1995-01-01

    During the last three years. the NASA/Thiokol/industry team has developed and started implementation of an environmentally sound manufacturing plan for the continued production of solid rocket motors. NASA Marshall Space Flight Center (MSFC) and Thiokol Corporation have worked with other industry representatives and the U.S. Environmental Protection Agency (EPA) to prepare a comprehensive plan to eliminate all ozone depleting chemicals from manufacturing processes and reduce the use of other hazardous materials used to produce the space shuttle reusable solid rocket motors. The team used a classical approach for problem-solving combined with a creative synthesis of new approaches to attack this challenge.

  14. Reduced hazard chemicals for solid rocket motor production

    NASA Technical Reports Server (NTRS)

    Caddy, Larry A.; Bowman, Ross; Richards, Rex A.

    1995-01-01

    During the last three years. the NASA/Thiokol/industry team has developed and started implementation of an environmentally sound manufacturing plan for the continued production of solid rocket motors. NASA Marshall Space Flight Center (MSFC) and Thiokol Corporation have worked with other industry representatives and the U.S. Environmental Protection Agency (EPA) to prepare a comprehensive plan to eliminate all ozone depleting chemicals from manufacturing processes and reduce the use of other hazardous materials used to produce the space shuttle reusable solid rocket motors. The team used a classical approach for problem-solving combined with a creative synthesis of new approaches to attack this challenge.

  15. [A mathematical model for the chemical control of Aedes aegypti (Diptera: Culicidae) having acquired chemical resistance].

    PubMed

    Restrepo-Alape, Leonardo D; Toro-Zapata, Hernán D; Muñoz-Loaiza, Aníbal

    2010-12-01

    Dengue fever is a common vector-borne disease in tropical and subtropical areas. It is transmitted to humans by the bite of an infected female Aedes mosquito. Since no vaccines are currently available which can protect against infection, disease control relies on controlling the mosquito population. This work was aimed at modelling such mosquito's population dynamics regarding chemical control of the adult population and its acquired resistance to chemicals. The model was analysed by using classical dynamic system theory techniques and mosquito growth threshold was determined as this establishes when a particular population may prosper in the environment or when it is likely to disappear. A suitable chemical control strategy was developed from such threshold. Simulations were made in control and non-control scenarios; this determined the degree of control application effectiveness against different levels of acquired resistance.

  16. Mathematics.

    ERIC Educational Resources Information Center

    Mac Lane, Saunders

    1980-01-01

    This is a review of the current research in mathematics involving breadth of ideas. Research includes topics in number theory, classification of all finite simple groups, the representation of group aids in their application to the study of symmetry. (Author/SA)

  17. Mathematics.

    ERIC Educational Resources Information Center

    Costellano, Janet; Scaffa, Matthew

    The product of a Special Studies Institute, this teacher developed resource guide for the emotionally handicapped (K-6) presents 37 activities designed to develop mathematics concepts and skills utilizing the urban out-of-doors. Focus is on experiencing math models, patterns, problems, and relationships found in an urban environment. Activities…

  18. Systematically reduced chemical mechanisms for sulfur oxidation and pyrolysis

    SciTech Connect

    Cerru, F.G.; Kronenburg, A.; Lindstedt, R.P.

    2006-08-15

    Recent research on sulfur chemistry has predominantly focused on the high-temperature chemistry typical of flames. The present work initially assesses the ability of a sulfur submechanism featuring 12 sulfur-containing species and 70 reversible reactions to reproduce measured data. The functionality includes the pyrolysis and oxidation of hydrogen sulfide as well as the chemistry of sulfur dioxide. The sensitivity of reaction paths to alternative rate determinations has been analyzed. In particular, the consumption paths of sulfanyl and the rates of the reactions involved in the SO{sub 2}-catalyzed radical recombination highlight existing uncertainties. Despite these difficulties, the detailed mechanism generally produces good agreement with experimental data. Most industrial combustion processes are turbulent and turbulence-chemistry interactions cannot be included through high-Damkohler-number limit approximations. Accordingly, chemical kinetic effects need to be accounted for and the implementation of systematically reduced mechanisms has the potential to increase the computational efficiency. The detailed reaction mechanism is thus subsequently reduced to six independent scalars with HSO, HOSO, HOSO{sub 2}, HSSH, and S in steady state. The reduced mechanism provides good agreement over the range of conditions studied. Further simplifications are made in the context of oxides of sulfur and a two-step mechanism involving SO, SO{sub 2}, and SO{sub 3} is derived and shown to retain good agreement with the experimental data for a more limited set of conditions. (author)

  19. A multipurpose reduced chemical-kinetic mechanism for methanol combustion

    NASA Astrophysics Data System (ADS)

    Fernández-Tarrazo, Eduardo; Sánchez-Sanz, Mario; Sánchez, Antonio L.; Williams, Forman A.

    2016-07-01

    A multipurpose reduced chemical-kinetic mechanism for methanol combustion comprising 8 overall reactions and 11 reacting chemical species is presented. The development starts by investigating the minimum set of elementary reactions needed to describe methanol combustion with reasonable accuracy over a range of conditions of temperature, pressure, and composition of interest in combustion. Starting from a 27-step mechanism that has been previously tested and found to give accurate predictions of ignition processes for these conditions, it is determined that the addition of 11 elementary reactions taken from its basis (San Diego) mechanism extends the validity of the description to premixed-flame propagation, strain-induced extinction of non-premixed flames, and equilibrium composition and temperatures, giving results that compare favourably with experimental measurements and also with computations using the 247-step detailed San Diego mechanism involving 50 reactive species. Specifically, premixed-flame propagation velocities and extinction strain rates for non-premixed counterflow flames calculated with the 38-step mechanism show departures from experimental measurements and detailed-chemistry computations that are roughly on the order of 10%, comparable with expected experimental uncertainties. Similar accuracy is found in comparisons of autoignition times over the range considered, except at very high temperatures, under which conditions the computations tend to overpredict induction times for all of the chemistry descriptions tested. From this 38-step mechanism, the simplification is continued by introducing steady-state approximations for the intermediate species CH3, CH4, HCO, CH3O, CH2OH, and O, leading to an 8-step reduced mechanism that provides satisfactory accuracy for all conditions tested. The flame computations indicate that thermal diffusion has a negligible influence on methanol combustion in all cases considered and that a mixture-average species

  20. Multi-criteria optimisation problems for chemical engineering systems and algorithms for their solution based on fuzzy mathematical methods.

    PubMed

    Orazbayev, B B; Orazbayeva, K N; Kurmangaziyeva, L T; Makhatova, V E

    2015-01-01

    Mathematical equations for the multi-criteria task of the optimisation of chemical engineering systems, for example for the optimisation of working regimes for industrial installations for benzene production, have been formulated and developed, and based on fuzzy mathematical methods, algorithms for their solution have been developed. Since the chemical engineering system, which is being researched, is characterised by multiple criteria and often functions in conditions of uncertainty, the presenting problem is formulated in the form of multi-criteria equations for fuzzy mathematical programming. New mathematical formulations for the problems being solved in a fuzzy environment and heuristic algorithms for their solution have been developed by the modification of various optimisation principles based on fuzzy mathematical methods.

  1. Multi-criteria optimisation problems for chemical engineering systems and algorithms for their solution based on fuzzy mathematical methods

    PubMed Central

    Orazbayev, B. B.; Orazbayeva, K. N.; Kurmangaziyeva, L. T.; Makhatova, V.E.

    2015-01-01

    Mathematical equations for the multi-criteria task of the optimisation of chemical engineering systems, for example for the optimisation of working regimes for industrial installations for benzene production, have been formulated and developed, and based on fuzzy mathematical methods, algorithms for their solution have been developed. Since the chemical engineering system, which is being researched, is characterised by multiple criteria and often functions in conditions of uncertainty, the presenting problem is formulated in the form of multi-criteria equations for fuzzy mathematical programming. New mathematical formulations for the problems being solved in a fuzzy environment and heuristic algorithms for their solution have been developed by the modification of various optimisation principles based on fuzzy mathematical methods. PMID:28275318

  2. Magnetism in pristine and chemically reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Diamantopoulou, A.; Glenis, S.; Zolnierkiwicz, G.; Guskos, N.; Likodimos, V.

    2017-01-01

    The evolution of magnetism for graphene oxide (GO) before and after chemical reduction was investigated by means of static magnetization and electron spin resonance (ESR) spectroscopy. Strong paramagnetism with a saturation magnetization of ˜1.2 emu/g and weak antiferromagnetic interactions were identified in pristine GO. Apart from spin-half defect centers, ESR spectroscopy indicated the excitation of high spin states, consistently with the high spin (S = 2) magnetic moments derived from the magnetization analysis, corroborating the formation of spatially "isolated" magnetic clusters in GO. A marked reduction of GO's magnetization (˜0.17 emu/g) along with an appreciable rise of diamagnetism (-2.4 × 10-6 emu/g Oe) was detected after chemical reduction by sodium borohydride, reflecting the drastic removal of paramagnetic defects and the concomitant growth of sp2 domains in reduced graphene oxide (rGO). ESR revealed a large drop of the spin susceptibility for rGO, which, in addition to the main paramagnetic Curie component, showed an appreciable Pauli contribution. The latter together with the g-factor shift and the broadening of the ESR line indicated the coupling of localized spins with conduction electrons. The rGO ESR signal presented a metallic line shape, which could be analyzed in terms of two separate spectral components, a broad one that may be related to defect states strongly coupled with itinerant spins within the sp2 clusters and a narrow one due to edge/vacancy defect spins, indicative of rGO's persistent structural inhomogeneity.

  3. A general mathematical model for chemical-enhanced flushing of soil contaminated by organic compounds

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Brusseau, Mark L.

    The use of chemical agents to enhance the in situ removal of hydrophobic organic compounds (HOCs) from porous media is an emerging remediation technology. Whereas surfactants and cosolvents are the primary agents examined to date, others, such as natural organic matter and complexing agents, have also been examined for their ability to enhance the solubilization of HOCs. While the mode of action of each type of enhanced-solubilization agent may be different, they all induce similar responses. In this paper, a general mathematical model is developed to simulate the enhanced-solubilization process for various chemical agents, including cosolvents, surfactants, natural organic matter, and complexing agents. This model is developed using a master-equation approach that incorporates the solubilization mechanisms associated with each type of agent. A limited evaluation of the model is conducted by comparing simulations to the results of two laboratory experiments. A sensitivity analysis is performed to illustrate the influence of various factors on contaminant removal.

  4. Mathematical Modeling to Reduce Waste of Compounded Sterile Products in Hospital Pharmacies

    PubMed Central

    Dobson, Gregory; Haas, Curtis E.; Tilson, David

    2014-01-01

    Abstract In recent years, many US hospitals embarked on “lean” projects to reduce waste. One advantage of the lean operational improvement methodology is that it relies on process observation by those engaged in the work and requires relatively little data. However, the thoughtful analysis of the data captured by operational systems allows the modeling of many potential process options. Such models permit the evaluation of likely waste reductions and financial savings before actual process changes are made. Thus the most promising options can be identified prospectively, change efforts targeted accordingly, and realistic targets set. This article provides one example of such a datadriven process redesign project focusing on waste reduction in an in-hospital pharmacy. A mathematical model of the medication prepared and delivered by the pharmacy is used to estimate the savings from several potential redesign options (rescheduling the start of production, scheduling multiple batches, or reordering production within a batch) as well as the impact of information system enhancements. The key finding is that mathematical modeling can indeed be a useful tool. In one hospital setting, it estimated that waste could be realistically reduced by around 50% by using several process changes and that the greatest benefit would be gained by rescheduling the start of production (for a single batch) away from the period when most order cancellations are made. PMID:25477580

  5. Mathematical modeling to reduce waste of compounded sterile products in hospital pharmacies.

    PubMed

    Tilson, Vera; Dobson, Gregory; Haas, Curtis E; Tilson, David

    2014-07-01

    In recent years, many US hospitals embarked on "lean" projects to reduce waste. One advantage of the lean operational improvement methodology is that it relies on process observation by those engaged in the work and requires relatively little data. However, the thoughtful analysis of the data captured by operational systems allows the modeling of many potential process options. Such models permit the evaluation of likely waste reductions and financial savings before actual process changes are made. Thus the most promising options can be identified prospectively, change efforts targeted accordingly, and realistic targets set. This article provides one example of such a datadriven process redesign project focusing on waste reduction in an in-hospital pharmacy. A mathematical model of the medication prepared and delivered by the pharmacy is used to estimate the savings from several potential redesign options (rescheduling the start of production, scheduling multiple batches, or reordering production within a batch) as well as the impact of information system enhancements. The key finding is that mathematical modeling can indeed be a useful tool. In one hospital setting, it estimated that waste could be realistically reduced by around 50% by using several process changes and that the greatest benefit would be gained by rescheduling the start of production (for a single batch) away from the period when most order cancellations are made.

  6. [Reducing nutrients loss by plastic film covering chemical fertilizers].

    PubMed

    Chen, Huo-jun; Wei, Ze-bin; Wu, Qi-tang; Zeng, Shu-cai

    2010-03-01

    With the low utilization rate of fertilizers by crop and the growing amount of fertilizer usage,the agricultural non-point source pollution in China is becoming more and more serious. The field experiments planting corns were conducted, in which the applied chemical fertilizers were recovered with plastic film to realize the separation of fertilizers from rain water. In the experiments, the influences of different fertilizing treatments on the growing and production of sweet corn were observed. The fertilizer utilization rate and the nutrient contents in surface run-off water with and without the film covering were also determined. Results showed that, with only 70% of the normal amount of fertilizers,the sweet corn could already get high yield under the experimental soil conditions. Soil analysis after corn crops showed that the amounts of available N, P and K in the soil increased obviously with the film-covering, and the decreasing order was: 100% fertilizers with film-covering > 70% fertilizers with film-covering > 100% fertilizers, 70% fertilizers > no fertilizer. The average utilization coefficients of fertilizers by the crop were 42%-87%, 0%-3%, 5%-15% respectively for N, P and K. It was higher with film-covering than that without covering, especially for the high fertilization treatment. Analysis of water samples collected for eight run-off events showed that, without film-covering, N, P and K average concentrations in the runoff waters with fertilizations were 27.72, 2.70 and 7.07 mg x L(-1), respectively. And they were reduced respectively by 39.54%, 28.05%, 43.74% with the film-covering. This can give significant benefits to the decrease of agricultural non-point source pollution and water eutrophication.

  7. Perceptions of College Students on Successful Strategies for Reducing Mathematics Anxiety

    ERIC Educational Resources Information Center

    Allen, Amelia Ann

    2011-01-01

    Despite more than 50 years of attempts to improve mathematics education and the simultaneous prevalence of fears associated with learning mathematics in the United States, the problem of mathematics anxiety among students still remains. This qualitative phenomenological study was focused on understanding college students' perceptions regarding the…

  8. Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling

    SciTech Connect

    Randall S. Seright

    2007-09-30

    This final technical progress report describes work performed from October 1, 2004, through May 16, 2007, for the project, 'Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling'. We explored the potential of pore-filling gels for reducing excess water production from both fractured and unfractured production wells. Several gel formulations were identified that met the requirements--i.e., providing water residual resistance factors greater than 2,000 and ultimate oil residual resistance factors (F{sub rro}) of 2 or less. Significant oil throughput was required to achieve low F{sub rro} values, suggesting that gelant penetration into porous rock must be small (a few feet or less) for existing pore-filling gels to provide effective disproportionate permeability reduction. Compared with adsorbed polymers and weak gels, strong pore-filling gels can provide greater reliability and behavior that is insensitive to the initial rock permeability. Guidance is provided on where relative-permeability-modification/disproportionate-permeability-reduction treatments can be successfully applied for use in either oil or gas production wells. When properly designed and executed, these treatments can be successfully applied to a limited range of oilfield excessive-water-production problems. We examined whether gel rheology can explain behavior during extrusion through fractures. The rheology behavior of the gels tested showed a strong parallel to the results obtained from previous gel extrusion experiments. However, for a given aperture (fracture width or plate-plate separation), the pressure gradients measured during the gel extrusion experiments were much higher than anticipated from rheology measurements. Extensive experiments established that wall slip and first normal stress difference were not responsible for the pressure gradient discrepancy. To explain the discrepancy, we noted that the aperture for gel flow (for mobile gel wormholing through concentrated immobile

  9. Mathematical modeling in chemical engineering: from lab-scale to field studies

    NASA Astrophysics Data System (ADS)

    Pushpavanam, S.

    2010-10-01

    In this work we discuss four different problems where mathematical modeling gives us insight into system behavior. Most chemical plants are characterized by an upstream reactor coupled to a downstream separator unit via a recycle stream. The steady state behavior of a representative system is analyzed for the maximum number of steady states which are admissible Different flow regimes in single and two phase-flows are discussed with a view to understanding mixing phenomena in micro-fluidics. In single phase flows Deans vortices cause mixing while in two phase slugs the mixing is caused by internal circulations. Bubble column reactors are heterogeneous systems characterized by turbulent flows. Flow fields are measured experimentally using PIV and these can be validated using computational fluid dynamics. In the context of Air Quality monitoring, field data are analyzed using statistical methods. This is used to predict source contributions to air quality levels in a region and to evaluate different control options.

  10. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    SciTech Connect

    Volokitin, Oleg Volokitin, Gennady Skripnikova, Nelli Shekhovtsov, Valentin; Vlasov, Viktor

    2016-01-15

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  11. Evaluation of a static granular bed reactor using a chemical oxygen demand balance and mathematical modeling.

    PubMed

    Lim, Seung Joo; Fox, Peter; Ellis, Timothy G

    2011-06-01

    In order to evaluate the static granular bed reactor (SGBR), a chemical oxygen demand (COD) balance was used along with a mathematical model. The SGBR was operated with an organic loading rate (OLR) ranging from 0.8 to 5.5 kg/m(3) day at 24°C. The average COD removal efficiency was 87.4%, and the removal efficiencies of COD, carbohydrates, and proteins increased with an OLR, while the lipids removal efficiency was not a function of an OLR. From the results of the COD balance, the yield of biomass increased with an OLR. The SGBR was modeled using the general transport equation considering advection, diffusion, and degradation by microorganisms, and the first-order reaction rate constant was 0.0166/day. The simulation results were in excellent agreement with experimental data. In addition, the SGBR model provided mechanistic insight into why the COD removal efficiency in the SGBR is proportional to an OLR.

  12. 76 FR 41371 - Impact of Reducing the Mixture Concentration Threshold for Commercial Schedule 3 Chemical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ... Reducing the Mixture Concentration Threshold for Commercial Schedule 3 Chemical Activities Under the... CFR Part 714 Impact of Reducing the Mixture Concentration Threshold for Commercial Schedule 3 Chemical... concentration level at which the CWCR exempt certain mixtures containing Schedule 3 chemicals from the...

  13. Mathematical modeling of chemical composition modification and etching of polymers under the atomic oxygen influence

    NASA Astrophysics Data System (ADS)

    Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

    2016-07-01

    Atomic oxygen (AO) of the upper atmosphere is one of the most important space factors that can cause degradation of spacecraft surface. In our previous mathematical model the Monte Carlo method and the "large particles" approximation were used for simulating processes of polymer etching under the influence of AO [1]. The interaction of enlarged AO particles with the polymer was described in terms of probabilities of reactions such as etching of polymer and specular and diffuse scattering of the AO particles on polymer. The effects of atomic oxygen on protected polymers and microfiller containing composites were simulated. The simulation results were in quite good agreement with the results of laboratory experiments on magnetoplasmadynamic accelerator of the oxygen plasma of SINP MSU [2]. In this paper we present a new model that describes the reactions of AO interactions with polymeric materials in more detail. Reactions of formation and further emission of chemical compounds such as CO, CO _{2}, H _{2}O, etc. cause the modification of the chemical composition of the polymer and change the probabilities of its consequent interaction with the AO. The simulation results are compared with the results of previous simulation and with the results of laboratory experiments. The reasons for the differences between the results of natural experiments on spacecraft, laboratory experiments and simulations are discussed. N. Chirskaya, M. Samokhina, Computer modeling of polymer structures degradation under the atomic oxygen exposure, WDS'12 Proceedings of Contributed Papers: Part III - Physics, Matfyzpress Prague, 2012, pp. 30-35. E. Voronina, L. Novikov, V. Chernik, N. Chirskaya, K. Vernigorov, G. Bondarenko, and A. Gaidar, Mathematical and experimental simulation of impact of atomic oxygen of the earth's upper atmosphere on nanostructures and polymer composites, Inorganic Materials: Applied Research, 2012, vol. 3, no. 2, pp. 95-101.

  14. Novel in vitro and mathematical models for the prediction of chemical toxicity.

    PubMed

    Williams, Dominic P; Shipley, Rebecca; Ellis, Marianne J; Webb, Steve; Ward, John; Gardner, Iain; Creton, Stuart

    2013-01-01

    The focus of much scientific and medical research is directed towards understanding the disease process and defining therapeutic intervention strategies. The scientific basis of drug safety is very complex and currently remains poorly understood, despite the fact that adverse drug reactions (ADRs) are a major health concern and a serious impediment to development of new medicines. Toxicity issues account for ∼21% drug attrition during drug development and safety testing strategies require considerable animal use. Mechanistic relationships between drug plasma levels and molecular/cellular events that culminate in whole organ toxicity underpins development of novel safety assessment strategies. Current in vitro test systems are poorly predictive of toxicity of chemicals entering the systemic circulation, particularly to the liver. Such systems fall short because of (1) the physiological gap between cells currently used and human hepatocytes existing in their native state, (2) the lack of physiological integration with other cells/systems within organs, required to amplify the initial toxicological lesion into overt toxicity, (3) the inability to assess how low level cell damage induced by chemicals may develop into overt organ toxicity in a minority of patients, (4) lack of consideration of systemic effects. Reproduction of centrilobular and periportal hepatocyte phenotypes in in vitro culture is crucial for sensitive detection of cellular stress. Hepatocyte metabolism/phenotype is dependent on cell position along the liver lobule, with corresponding differences in exposure to substrate, oxygen and hormone gradients. Application of bioartificial liver (BAL) technology can encompass in vitro predictive toxicity testing with enhanced sensitivity and improved mechanistic understanding. Combining this technology with mechanistic mathematical models describing intracellular metabolism, fluid-flow, substrate, hormone and nutrient distribution provides the opportunity to

  15. Novel in vitro and mathematical models for the prediction of chemical toxicity

    PubMed Central

    Shipley, Rebecca; Ellis, Marianne J.; Webb, Steve; Ward, John; Gardner, Iain; Creton, Stuart

    2013-01-01

    The focus of much scientific and medical research is directed towards understanding the disease process and defining therapeutic intervention strategies. The scientific basis of drug safety is very complex and currently remains poorly understood, despite the fact that adverse drug reactions (ADRs) are a major health concern and a serious impediment to development of new medicines. Toxicity issues account for ∼21% drug attrition during drug development and safety testing strategies require considerable animal use. Mechanistic relationships between drug plasma levels and molecular/cellular events that culminate in whole organ toxicity underpins development of novel safety assessment strategies. Current in vitro test systems are poorly predictive of toxicity of chemicals entering the systemic circulation, particularly to the liver. Such systems fall short because of (1) the physiological gap between cells currently used and human hepatocytes existing in their native state, (2) the lack of physiological integration with other cells/systems within organs, required to amplify the initial toxicological lesion into overt toxicity, (3) the inability to assess how low level cell damage induced by chemicals may develop into overt organ toxicity in a minority of patients, (4) lack of consideration of systemic effects. Reproduction of centrilobular and periportal hepatocyte phenotypes in in vitro culture is crucial for sensitive detection of cellular stress. Hepatocyte metabolism/phenotype is dependent on cell position along the liver lobule, with corresponding differences in exposure to substrate, oxygen and hormone gradients. Application of bioartificial liver (BAL) technology can encompass in vitro predictive toxicity testing with enhanced sensitivity and improved mechanistic understanding. Combining this technology with mechanistic mathematical models describing intracellular metabolism, fluid-flow, substrate, hormone and nutrient distribution provides the opportunity to

  16. Gage of 6.5 per cent Si-Fe sheet is chemically reduced

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Pavlovic, D. M.

    1966-01-01

    Chemical milling process aids the production of 6.5 percent silicon-iron soft magnetic-alloy sheets to very thin gages. Following conventional rolling to safe gage limits, the material is chemically reduced to the desired gage.

  17. Transport of reacting solutes in porous media: Relation between mathematical nature of problem formulation and chemical nature of reactions

    USGS Publications Warehouse

    Rubin, Jacob

    1983-01-01

    Examples involving six broad reaction classes show that the nature of transport-affecting chemistry may have a profound effect on the mathematical character of solute transport problem formulation. Substantive mathematical diversity among such formulations is brought about principally by reaction properties that determine whether (1) the reaction can be regarded as being controlled by local chemical equilibria or whether it must be considered as being controlled by kinetics, (2) the reaction is homogeneous or heterogeneous, (3) the reaction is a surface reaction (adsorption, ion exchange) or one of the reactions of classical chemistry (e.g., precipitation, dissolution, oxidation, reduction, complex formation). These properties, as well as the choice of means to describe them, stipulate, for instance, (1) the type of chemical entities for which a formulation's basic, mass-balance equations should be written; (2) the nature of mathematical transformations needed to change the problem's basic equations into operational ones. These and other influences determine such mathematical features of problem formulations as the nature of the operational transport-equation system (e.g., whether it involves algebraic, partial-differential, or integro-partial-differential simultaneous equations), the type of nonlinearities of such a system, and the character of the boundaries (e.g., whether they are stationary or moving). Exploration of the reasons for the dependence of transport mathematics on transport chemistry suggests that many results of this dependence stem from the basic properties of the reactions' chemical-relation (i.e., equilibrium or rate) equations.

  18. Chemically Based Mathematical Model for Development of Cerebral Cortical Folding Patterns

    PubMed Central

    Striegel, Deborah A.; Hurdal, Monica K.

    2009-01-01

    The mechanism for cortical folding pattern formation is not fully understood. Current models represent scenarios that describe pattern formation through local interactions, and one recent model is the intermediate progenitor model. The intermediate progenitor (IP) model describes a local chemically driven scenario, where an increase in intermediate progenitor cells in the subventricular zone correlates to gyral formation. Here we present a mathematical model that uses features of the IP model and further captures global characteristics of cortical pattern formation. A prolate spheroidal surface is used to approximate the ventricular zone. Prolate spheroidal harmonics are applied to a Turing reaction-diffusion system, providing a chemically based framework for cortical folding. Our model reveals a direct correlation between pattern formation and the size and shape of the lateral ventricle. Additionally, placement and directionality of sulci and the relationship between domain scaling and cortical pattern elaboration are explained. The significance of this model is that it elucidates the consistency of cortical patterns among individuals within a species and addresses inter-species variability based on global characteristics and provides a critical piece to the puzzle of cortical pattern formation. PMID:19779554

  19. Exploring Effects of High School Students' Mathematical Processing Skills and Conceptual Understanding of Chemical Concepts on Algorithmic Problem Solving

    ERIC Educational Resources Information Center

    Gultepe, Nejla; Yalcin Celik, Ayse; Kilic, Ziya

    2013-01-01

    The purpose of the study was to examine the effects of students' conceptual understanding of chemical concepts and mathematical processing skills on algorithmic problem-solving skills. The sample (N = 554) included grades 9, 10, and 11 students in Turkey. Data were collected using the instrument "MPC Test" and with interviews. The MPC…

  20. Converting STEM Doctoral Dissertations into Patent Applications: A Study of Chemistry, Physics, Mathematics, and Chemical Engineering Dissertations from CIC Institutions

    ERIC Educational Resources Information Center

    Butkovich, Nancy J.

    2015-01-01

    Doctoral candidates may request short-term embargoes on the release of their dissertations in order to apply for patents. This study examines how often inventions described in dissertations in chemical engineering, chemistry, physics, and mathematics are converted into U.S. patent applications, as well as the relationship between dissertation…

  1. Converting STEM Doctoral Dissertations into Patent Applications: A Study of Chemistry, Physics, Mathematics, and Chemical Engineering Dissertations from CIC Institutions

    ERIC Educational Resources Information Center

    Butkovich, Nancy J.

    2015-01-01

    Doctoral candidates may request short-term embargoes on the release of their dissertations in order to apply for patents. This study examines how often inventions described in dissertations in chemical engineering, chemistry, physics, and mathematics are converted into U.S. patent applications, as well as the relationship between dissertation…

  2. Application of chemical technology to reduce boiler fouling and corrosion

    SciTech Connect

    Proctor, B.; Kasen, B.; Bosinger, G.

    1981-01-01

    Fuel oil additives containing aluminum, supplied as a dispersion of magnesium, manganese and aluminum, have been used effectively to control boiler fouling and corrosion. This paper reviews the chemistry of sodium/vanadium deposits and discusses the use of chemical additives in dealing with the problem. It presents the results of a fuel treatment program to solve combustion problems at Sierra Pacific Power Corp. 9 refs.

  3. Using Propensity Scores to Reduce Selection Bias in Mathematics Education Research

    ERIC Educational Resources Information Center

    Graham, Suzanne E.

    2010-01-01

    Selection bias is a problem for mathematics education researchers interested in using observational rather than experimental data to make causal inferences about the effects of different instructional methods in mathematics on student outcomes. Propensity score methods represent 1 approach to dealing with such selection bias. This article…

  4. Evidence for shared genetic risk between ADHD symptoms and reduced mathematics ability: a twin study

    PubMed Central

    Greven, Corina U.; Kovas, Yulia; Willcutt, Erik G.; Petrill, Stephen A.; Plomin, Robert

    2013-01-01

    Background Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Methods Data came from more than 6,000 12-year-old twin pairs from the U.K. population-representative Twins Early Development Study. Parents rated each twin’s behaviour using a DSM-IV-based 18-item questionnaire of inattentive and hyperactive-impulsive ADHD symptoms. Mathematics tests based on the U.K. National Curriculum were completed by each twin. The twins also completed standardised tests of reading and general cognitive ability. Multivariate twin model fitting was applied. Results Inattentive and hyperactive-impulsive ADHD symptoms were highly heritable (67% and 73%, respectively). Mathematics ability was moderately heritable (46%). Mathematics ability and inattentiveness showed a significantly greater phenotypic correlation (rp=−0.26) and genetic correlation (rA=−0.41) than mathematics ability and hyperactivity-impulsivity (rp=−0.18; rA=−0.22). The genetic correlation between inattentiveness and mathematics ability was largely independent from hyperactivity-impulsivity, and was only partially accounted for by genetic influences related to reading and general cognitive ability. Conclusions Results revealed the novel finding that mathematics ability shows significantly stronger phenotypic and genetic associations with inattentiveness than with hyperactivity-impulsivity. Genetic associations between inattentiveness and mathematics ability could only partially be accounted for by hyperactivity-impulsivity, reading and general cognitive ability. Results suggest that mathematics ability is associated with ADHD symptoms largely because it shares genetic risk factors with inattentiveness, and provide further evidence for considering inattentiveness and hyperactivity-impulsivity separately. DNA markers for ADHD symptoms (especially inattentiveness) may also

  5. Evidence for shared genetic risk between ADHD symptoms and reduced mathematics ability: a twin study.

    PubMed

    Greven, Corina U; Kovas, Yulia; Willcutt, Erik G; Petrill, Stephen A; Plomin, Robert

    2014-01-01

    Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents rated each twin's behaviour using a DSM-IV-based 18-item questionnaire of inattentive and hyperactive-impulsive ADHD symptoms. Mathematics tests based on the UK National Curriculum were completed by each twin. The twins also completed standardised tests of reading and general cognitive ability. Multivariate twin model fitting was applied. Inattentive and hyperactive-impulsive ADHD symptoms were highly heritable (67% and 73% respectively). Mathematics ability was moderately heritable (46%). Mathematics ability and inattentiveness showed a significantly greater phenotypic correlation (r(p) = -.26) and genetic correlation (r(A) = -.41) than mathematics ability and hyperactivity-impulsivity (r(p) = -.18; r(A) = -.22). The genetic correlation between inattentiveness and mathematics ability was largely independent from hyperactivity-impulsivity, and was only partially accounted for by genetic influences related to reading and general cognitive ability. Results revealed the novel finding that mathematics ability shows significantly stronger phenotypic and genetic associations with inattentiveness than with hyperactivity-impulsivity. Genetic associations between inattentiveness and mathematics ability could only partially be accounted for by hyperactivity-impulsivity, reading and general cognitive ability. Results suggest that mathematics ability is associated with ADHD symptoms largely because it shares genetic risk factors with inattentiveness, and provide further evidence for considering inattentiveness and hyperactivity-impulsivity separately. DNA markers for ADHD symptoms (especially inattentiveness) may also be candidate risk factors for

  6. Reduced product yield in chemical processes by second law effects

    NASA Technical Reports Server (NTRS)

    England, C.; Funk, J. E.

    1980-01-01

    An analysis of second law effects in chemical processes, where product yield is explicitly related to the individual irreversibilities within the process to indicate a maximum theoretical yield, is presented. Examples are given that indicate differences between first and second law approaches toward process efficiency and process yield. This analysis also expresses production capacity in terms of the heating value of a product. As a result, it is particularly convenient in analyzing fuel conversion plants and their potential for improvement. Relationships are also given for the effects of irreversibilities on requirements for process heat and for feedstocks.

  7. Reducing disorder in graphene nanoribbons by chemical edge modification

    SciTech Connect

    Dauber, J.; Terrés, B.; Volk, C.; Stampfer, C.; Trellenkamp, S.

    2014-02-24

    We present electronic transport measurements on etched graphene nanoribbons on silicon dioxide before and after a short hydrofluoric acid (HF) treatment. We report on changes in the transport properties, in particular, in terms of a decreasing transport gap and a reduced doping level after HF dipping. Interestingly, the effective energy gap is nearly unaffected by the HF treatment. Additional measurements on a graphene nanoribbon with lateral graphene gates support strong indications that the HF significantly modifies the edges of the investigated nanoribbons leading to a significantly reduced disorder potential in these graphene nanostructures.

  8. Hazardous Chemicals on the Job: A Workers Guide to Reducing Exposure.

    ERIC Educational Resources Information Center

    Conrad, Fran; Kayman, Lindsey

    This guide is intended to assist workers in reducing their exposure to hazardous chemicals on the job. It describes a systematic preventive approach to hazardous chemicals that is based on the following steps: determining which chemicals are in use at a particular worksite (techniques for asking the company and steps to take if the company is…

  9. A Mathematical Formulation for the Effects of Nonlinear Chemical Reactions upon Taylor Dispersive Phenomena

    NASA Astrophysics Data System (ADS)

    Wright, E. S.; Aleem, T.

    2003-12-01

    In 1953, G.I.~Taylor published his landmark paper concerning the transport of a contaminant dissolved in a fluid flowing through a pipe of narrow diameter. He demonstrated that an interaction between the transverse variations in the fluid's velocity field and the transverse diffusion of the solute yielded an effective downstream mixing mechanism for the transverse average of the solute. This mechanism has since been dubbed ``Taylor Dispersion.'' Since his original publication, many related studies have surfaced. These include generalizations of channel geometry, generalizations of the velocity field (including turbulent field), applications to sedimentation problems, etc. However, much less attention has been given to the effects of nonlinear chemical reactions upon a system of solutes undergoing Taylor Dispersion. We present a rigorous mathematical model for the evolution of the transverse averages of reacting solutes that travel within a fluid flowing down a pipe of arbitrary cross-section. The technique for deriving this model is a generalization of a multiple scales perturbation approach described by P.C.~Fife for linear (reactionless) problems. The key outcome is that while one still finds an effective mechanism for downstream mixing, but also there is also a effective mechanism for nonlinear advection.

  10. Scramjet Combustor Simulations Using Reduced Chemical Kinetics for Practical Fuels

    DTIC Science & Technology

    2003-12-01

    Stochastic Simulation of an HCCI Engine Using an Automatically Reduced Mechanism,� ICE, Vol. 37-2, 2001 Fall Technical Conference...Christopher J. Montgomery, and Wei Zhao Reaction Engineering International (REI) 77 West 200 South, Suite 210 Salt Lake City, UT 84101 Dean R...DOUGLAS L. DAVIS CAPT. BRIAN C. MCDONALD AFRL/PRAS, Project Engineer Branch Chief Propulsion Sciences Branch Propulsion

  11. Equity and spatial reasoning: reducing the mathematical achievement gap in gender and social disadvantage

    NASA Astrophysics Data System (ADS)

    Lowrie, Tom; Jorgensen, Robyn

    2017-06-01

    Since the early 70s, there has been recognition that there are specific differences in achievement based on variables, such as gender and socio-economic background, in terms of mathematics performance. However, these differences are not unilateral but rather quite specific and relate strongly to spatial reasoning. This early work has paved the way for thinking critically about who achieves in mathematics and why. This project innovatively combines the strengths of the two Chief Investigators—Lowrie's work in spatial reasoning and Jorgensen's work in equity. The assumptions, the approach and theoretical framing used in the study unite quite disparate areas of mathematics education into a cogent research program that seeks to challenge some of the long-held views in the field of mathematics education.

  12. Chemical characterization of dissolvable tobacco products promoted to reduce harm.

    PubMed

    Rainey, Christina L; Conder, Paige A; Goodpaster, John V

    2011-03-23

    In 2009, the R. J. Reynolds Tobacco Co. released a line of dissolvable tobacco products that are marketed as an alternative to smoking in places where smoking is prohibited. These products are currently available in Indianapolis, IN, Columbus, OH, and Portland, OR. This paper describes the chemical characterization of four such products by gas chromatography-mass spectrometry (GC-MS). The dissolvable tobacco products were extracted and prepared by ultrasonic extraction using acetone, trimethylsilyl derivatization, and headspace solid phase microextraction (SPME). The following compounds were identified in the dissolvables using either ultrasonic extractions or trimethylsilyl derivatization: nicotine, ethyl citrate, palmitic acid, stearic acid, sorbitol, glycerol, and xylitol. The following compounds were identified in the dissolvables using headspace SPME: nicotine, ethyl citrate, cinnamaldehyde, coumarin, vanillin, and carvone. With the exception of nicotine, the compounds identified thus far in the dissolvables are either flavoring compounds or binders. The concentration of free nicotine in the dissolvables was determined from the Henderson-Hasselbalch equation and by measuring the pH and nicotine concentration by GC-MS. The results presented here are the first to reveal the complexity of dissolvable tobacco products and may be used to assess potential oral health effects.

  13. Design and chemical evaluation of reduced machine-yield cigarettes.

    PubMed

    McAdam, K G; Gregg, E O; Bevan, M; Dittrich, D J; Hemsley, S; Liu, C; Proctor, C J

    2012-02-01

    Experimental cigarettes (ECs) were made by combining technological applications that individually reduce the machine measured yields of specific toxicants or groups of toxicants in mainstream smoke (MS). Two tobacco blends, featuring a tobacco substitute sheet or a tobacco blend treatment, were combined with filters containing an amine functionalised resin (CR20L) and/or a polymer-derived, high activity carbon adsorbent to generate three ECs with the potential for generating lower smoke toxicant yields than conventional cigarettes. MS yields of smoke constituents were determined under 4 different smoking machine conditions. Health Canada Intense (HCI) machine smoking conditions gave the highest MS yields for nicotine-free dry particulate matter and for most smoke constituents measured. Toxicant yields from the ECs were compared with those from two commercial comparator cigarettes, three scientific control cigarettes measured contemporaneously and with published data on 120 commercial cigarettes. The ECs were found to generate some of the lowest machine yields of toxicants from cigarettes for which published HCI smoke chemistry data are available; these comparisons therefore confirm that ECs with reduced MS machine toxicant yields compared to commercial cigarettes can be produced. The results encourage further work examining human exposure to toxicants from these cigarettes, including human biomarker studies.

  14. Prospects for managing turfgrass pests with reduced chemical inputs.

    PubMed

    Held, David W; Potter, Daniel A

    2012-01-01

    Turfgrass culture, a multibillion dollar industry in the United States, poses unique challenges for integrated pest management. Why insect control on lawns, golf courses, and sport fields remains insecticide-driven, and how entomological research and extension can best support nascent initiatives in environmental golf and sustainable lawn care are explored. High standards for aesthetics and playability, prevailing business models, risk management-driven control decisions, and difficulty in predicting pest outbreaks fuel present reliance on preventive insecticides. New insights into pest biology, sampling methodology, microbial insecticides, plant resistance, and conservation biological control are reviewed. Those gains, and innovations in reduced-risk insecticides, should make it possible to begin constructing holistic management plans for key turfgrass pests. Nurturing the public's interest in wildlife habitat preservation, including beneficial insects, may be one means to change aesthetic perceptions and gain leeway for implementing integrated pest management practices that lend stability to turfgrass settings.

  15. Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

    PubMed Central

    Ambrosi, Adriano; Chua, Chun Kiang; Khezri, Bahareh; Sofer, Zdeněk; Webster, Richard D.; Pumera, Martin

    2012-01-01

    Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000 °C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research. PMID:22826262

  16. Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite.

    PubMed

    Ambrosi, Adriano; Chua, Chun Kiang; Khezri, Bahareh; Sofer, Zdeněk; Webster, Richard D; Pumera, Martin

    2012-08-07

    Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000 °C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research.

  17. A mathematical model of the immune and neuroendocrine systems mutual regulation under the technogenic chemical factors impact.

    PubMed

    Zaitseva, N V; Kiryanov, D A; Lanin, D V; Chigvintsev, V M

    2014-01-01

    The concept of the triad regulatory metasystem, which includes the neuroendocrine and immune regulation systems, is currently generally accepted. Changes occurring in each of the regulatory systems in response to the impact of technogenic chemical factors are also well known. This paper presents mathematical models of the immune and neuroendocrine system functioning, using the interaction between these systems in response to bacterial invasion as an example, and changes in their performance under exposure to chemical factors, taking into account the stage of functional disorders in a producing organ, using the performance of the bone marrow as an example.

  18. 76 FR 41365 - Impact of Reducing the Mixture Concentration Threshold for Commercial Schedule 2A Chemical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ... Impact of Reducing the Mixture Concentration Threshold for Commercial Schedule 2A Chemical Activities... Security 15 CFR Parts 713 and 716 RIN 0694-XA27 Impact of Reducing the Mixture Concentration Threshold for... Regulations (CWCR) to reduce the concentration level below which the CWCR exempt certain mixtures containing a...

  19. Evidence for Shared Genetic Risk between ADHD Symptoms and Reduced Mathematics Ability: A Twin Study

    ERIC Educational Resources Information Center

    Greven, Corina U.; Kovas, Yulia; Willcutt, Erik G.; Petrill, Stephen A.; Plomin, Robert

    2013-01-01

    Background: Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Methods: Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents…

  20. Reduce, Reuse, Recycle: Resources and Strategies for the Use of Writing Projects in Mathematics

    ERIC Educational Resources Information Center

    Latulippe, Joe; Latulippe, Christine

    2014-01-01

    As an often recommended but under-utilized pedagogical strategy, writing in mathematics has many benefits for students. However, creating and grading worthwhile writing projects can be more time-consuming than utilizing more traditional forms of assessment. This paper provides a concrete example of a writing project prompt, questions, directions,…

  1. Reduce, Reuse, Recycle: Resources and Strategies for the Use of Writing Projects in Mathematics

    ERIC Educational Resources Information Center

    Latulippe, Joe; Latulippe, Christine

    2014-01-01

    As an often recommended but under-utilized pedagogical strategy, writing in mathematics has many benefits for students. However, creating and grading worthwhile writing projects can be more time-consuming than utilizing more traditional forms of assessment. This paper provides a concrete example of a writing project prompt, questions, directions,…

  2. Mathematics anxiety reduces default mode network deactivation in response to numerical tasks

    PubMed Central

    Pletzer, Belinda; Kronbichler, Martin; Nuerk, Hans-Christoph; Kerschbaum, Hubert H.

    2015-01-01

    Mathematics anxiety is negatively related to mathematics performance, thereby threatening the professional success. Preoccupation with the emotional content of the stimuli may consume working memory resources, which may be reflected in decreased deactivation of areas associated with the default mode network (DMN) activated during self-referential and emotional processing. The common problem is that math anxiety is usually associated with poor math performance, so that any group differences are difficult to interpret. Here we compared the BOLD-response of 18 participants with high (HMAs) and 18 participants with low mathematics anxiety (LMAs) matched for their mathematical performance to two numerical tasks (number comparison, number bisection). During both tasks, we found stronger deactivation within the DMN in LMAs compared to HMAs, while BOLD-response in task-related activation areas did not differ between HMAs and LMAs. The difference in DMN deactivation between the HMA and LMA group was more pronounced in stimuli with additional requirement on inhibitory functions, but did not differ between number magnitude processing and arithmetic fact retrieval. PMID:25954179

  3. Mathematics anxiety reduces default mode network deactivation in response to numerical tasks.

    PubMed

    Pletzer, Belinda; Kronbichler, Martin; Nuerk, Hans-Christoph; Kerschbaum, Hubert H

    2015-01-01

    Mathematics anxiety is negatively related to mathematics performance, thereby threatening the professional success. Preoccupation with the emotional content of the stimuli may consume working memory resources, which may be reflected in decreased deactivation of areas associated with the default mode network (DMN) activated during self-referential and emotional processing. The common problem is that math anxiety is usually associated with poor math performance, so that any group differences are difficult to interpret. Here we compared the BOLD-response of 18 participants with high (HMAs) and 18 participants with low mathematics anxiety (LMAs) matched for their mathematical performance to two numerical tasks (number comparison, number bisection). During both tasks, we found stronger deactivation within the DMN in LMAs compared to HMAs, while BOLD-response in task-related activation areas did not differ between HMAs and LMAs. The difference in DMN deactivation between the HMA and LMA group was more pronounced in stimuli with additional requirement on inhibitory functions, but did not differ between number magnitude processing and arithmetic fact retrieval.

  4. Evidence for Shared Genetic Risk between ADHD Symptoms and Reduced Mathematics Ability: A Twin Study

    ERIC Educational Resources Information Center

    Greven, Corina U.; Kovas, Yulia; Willcutt, Erik G.; Petrill, Stephen A.; Plomin, Robert

    2013-01-01

    Background: Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Methods: Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents…

  5. The mathematical properties of the quasi-chemical model for microorganism growth-death kinetics in foods.

    PubMed

    Ross, E W; Taub, I A; Doona, C J; Feeherry, F E; Kustin, K

    2005-03-15

    Knowledge of the mathematical properties of the quasi-chemical model [Taub, Feeherry, Ross, Kustin, Doona, 2003. A quasi-chemical kinetics model for the growth and death of Staphylococcus aureus in intermediate moisture bread. J. Food Sci. 68 (8), 2530-2537], which is used to characterize and predict microbial growth-death kinetics in foods, is important for its applications in predictive microbiology. The model consists of a system of four ordinary differential equations (ODEs), which govern the temporal dependence of the bacterial life cycle (the lag, exponential growth, stationary, and death phases, respectively). The ODE system derives from a hypothetical four-step reaction scheme that postulates the activity of a critical intermediate as an antagonist to growth (perhaps through a quorum sensing biomechanism). The general behavior of the solutions to the ODEs is illustrated by several examples. In instances when explicit mathematical solutions to these ODEs are not obtainable, mathematical approximations are used to find solutions that are helpful in evaluating growth in the early stages and again near the end of the process. Useful solutions for the ODE system are also obtained in the case where the rate of antagonist formation is small. The examples and the approximate solutions provide guidance in the parameter estimation that must be done when fitting the model to data. The general behavior of the solutions is illustrated by examples, and the MATLAB programs with worked examples are included in the appendices for use by predictive microbiologists for data collected independently.

  6. Laser-induced chemical liquid phase deposition of copper from aqueous solutions without reducing agents

    SciTech Connect

    Kochemirovsky, V A; Tumkin, I I; Logunov, L S; Safonov, S V; Menchikov, Leonid G

    2012-08-31

    Laser-induced chemical liquid phase deposition of copper without a traditional reducing agent has been used for the first time to obtain conductive patterns on a dielectric surface having a reducing ability. It is shown that phenol-formaldehyde binder of the dielectric (glass fibre) can successfully play the role of a reducing agent in this process. The resulting copper sediments have low electrical resistance and good topology. (interaction of laser radiation with matter. laser plasmas)

  7. Mathematical anxiety is linked to reduced cognitive reflection: a potential road from discomfort in the mathematics classroom to susceptibility to biases

    PubMed Central

    2014-01-01

    Background When asked to solve mathematical problems, some people experience anxiety and threat, which can lead to impaired mathematical performance (Curr Dir Psychol Sci 11:181–185, 2002). The present studies investigated the link between mathematical anxiety and performance on the cognitive reflection test (CRT; J Econ Perspect 19:25–42, 2005). The CRT is a measure of a person’s ability to resist intuitive response tendencies, and it correlates strongly with important real-life outcomes, such as time preferences, risk-taking, and rational thinking. Methods In Experiments 1 and 2 the relationships between maths anxiety, mathematical knowledge/mathematical achievement, test anxiety and cognitive reflection were analysed using mediation analyses. Experiment 3 included a manipulation of working memory load. The effects of anxiety and working memory load were analysed using ANOVAs. Results Our experiments with university students (Experiments 1 and 3) and secondary school students (Experiment 2) demonstrated that mathematical anxiety was a significant predictor of cognitive reflection, even after controlling for the effects of general mathematical knowledge (in Experiment 1), school mathematical achievement (in Experiment 2) and test anxiety (in Experiments 1–3). Furthermore, Experiment 3 showed that mathematical anxiety and burdening working memory resources with a secondary task had similar effects on cognitive reflection. Conclusions Given earlier findings that showed a close link between cognitive reflection, unbiased decisions and rationality, our results suggest that mathematical anxiety might be negatively related to individuals’ ability to make advantageous choices and good decisions. PMID:25179230

  8. Mathematical anxiety is linked to reduced cognitive reflection: a potential road from discomfort in the mathematics classroom to susceptibility to biases.

    PubMed

    Morsanyi, Kinga; Busdraghi, Chiara; Primi, Caterina

    2014-09-01

    When asked to solve mathematical problems, some people experience anxiety and threat, which can lead to impaired mathematical performance (Curr Dir Psychol Sci 11:181-185, 2002). The present studies investigated the link between mathematical anxiety and performance on the cognitive reflection test (CRT; J Econ Perspect 19:25-42, 2005). The CRT is a measure of a person's ability to resist intuitive response tendencies, and it correlates strongly with important real-life outcomes, such as time preferences, risk-taking, and rational thinking. In Experiments 1 and 2 the relationships between maths anxiety, mathematical knowledge/mathematical achievement, test anxiety and cognitive reflection were analysed using mediation analyses. Experiment 3 included a manipulation of working memory load. The effects of anxiety and working memory load were analysed using ANOVAs. Our experiments with university students (Experiments 1 and 3) and secondary school students (Experiment 2) demonstrated that mathematical anxiety was a significant predictor of cognitive reflection, even after controlling for the effects of general mathematical knowledge (in Experiment 1), school mathematical achievement (in Experiment 2) and test anxiety (in Experiments 1-3). Furthermore, Experiment 3 showed that mathematical anxiety and burdening working memory resources with a secondary task had similar effects on cognitive reflection. Given earlier findings that showed a close link between cognitive reflection, unbiased decisions and rationality, our results suggest that mathematical anxiety might be negatively related to individuals' ability to make advantageous choices and good decisions.

  9. Facilitating Student Understanding of Buffering by an Integration of Mathematics and Chemical Concepts

    ERIC Educational Resources Information Center

    Curtright, Robert; Emry, Randall; Heaton, Ruth M.; Markwell, John

    2004-01-01

    We describe a simple undergraduate exercise involving the titration of a weak acid by a strong base using a pH meter and a micropipette. Students then use their data and carry out graphical analyses with a spreadsheet. The analyses involve using mathematical concepts such as first-derivative and semi-log plots and provide an opportunity for…

  10. Facilitating Student Understanding of Buffering by an Integration of Mathematics and Chemical Concepts

    ERIC Educational Resources Information Center

    Curtright, Robert; Emry, Randall; Heaton, Ruth M.; Markwell, John

    2004-01-01

    We describe a simple undergraduate exercise involving the titration of a weak acid by a strong base using a pH meter and a micropipette. Students then use their data and carry out graphical analyses with a spreadsheet. The analyses involve using mathematical concepts such as first-derivative and semi-log plots and provide an opportunity for…

  11. Mapping of drug-like chemical universe with reduced complexity molecular frameworks.

    PubMed

    Kontijevskis, Aleksejs

    2017-03-28

    The emergence of DNA-encoded chemical libraries (DEL) field in past decade has attracted attention of pharmaceutical industry as a powerful mechanism for the discovery of novel drug-like hits for various biological targets. Nuevolution Chemetics technology enables DNA encoded synthesis of billions of chemically diverse drug-like small molecule compounds, and the efficient screening and optimization of these, facilitating effective identification of drug candidates at an unprecedented speed and scale. Although many approaches have been developed by the cheminformatics community for the analysis and visualization of drug-like chemical space, most of them are restricted to the analysis of maximum few millions of compounds and cannot handle collections of 10(8)-10(12) compounds typical for DELs. To address this big chemical data challenge, we developed Reduced Complexity Molecular (RCM) frameworks methodology as an abstract and very general way of representing chemical structures. By further introducing RCM framework descriptors we constructed a global framework map of drug-like chemical space and demonstrate how chemical space occupied by multi-million-member drug-like Chemetics DNA-encoded libraries and virtual combinatorial libraries with >10(12) members could be analysed and mapped without a need for library enumeration. We further validate the approach by performing RCM framework-based searches in drug-like chemical universe and mapping Chemetics library selection outputs for LSD1 target on a global framework chemical space map.

  12. Development of mathematical models and methods for calculation of rail steel deformation resistance of various chemical composition

    NASA Astrophysics Data System (ADS)

    Umansky, A. A.; Golovatenko, A. V.; Kadykov, V. N.; Dumova, L. V.

    2016-09-01

    Using the device of the complex “Gleeble System 3800” the physical experimental studies of deformation resistance of chrome rail steel at different thermo-mechanical deformation parameters were carried out. On the basis of mathematical processing of experimental data the statistical model of dependence of the rail steel deformation resistance on the simultaneous influence of deformation degree, rate and temperature, as well as the steel chemical composition, was developed. The nature of influence of deformation parameters and the content of chemical elements in steel on its resistance to plastic deformation is scientifically substantiated. Verification of the adequacy of the proposed model by the comparative analysis of the calculated and actual rolling forces during passes in the universal rail-and-structural steel mill JSC “EVRAZ Consolidated West Siberian Metallurgical Plant” (“EVRAZ ZSMK”) showed the possibility of its use for development and improvement of new modes of rails rolling.

  13. Evaluation of chemical immersion treatments to reduce microbial populations in fresh beef.

    PubMed

    Kassem, Ahmed; Meade, Joseph; Gibbons, James; McGill, Kevina; Walsh, Ciara; Lyng, James; Whyte, Paul

    2017-09-05

    The aim of the current study was to assess the ability of a number of chemicals (acetic Acid (AA), citric acid (CA) lactic acid (LA), sodium decanoate (SD) and trisodium phosphate (TSP)) to reduce microbial populations (total viable count, Campylobacter jejuni, Escherichia coli, Salmonella typhimurium and Listeria monocytogenes) on raw beef using an immersion system. The following concentrations of each chemical were used: 3 & 5% for AA, CA, LA, SD and 10 &12% for TSP. Possible synergistic effects of using combinations of two chemicals sequentially (LA+CA and LA+AA) were also investigated. L*, a* and b* values were measured before and after treatments and ΔE* values were calculated in order to determine any changes in the color of meat due to the use of these chemicals. In general, all chemical treatments resulted in significantly (p<0.05) reduced bacterial counts when compared to untreated controls. The greatest reductions were obtained by using LA3%, SD5%, AA5%, LA5% and SD3% for TVC, C. jejuni, E. coli, S. typhimurium and L. monocytogenes, respectively. However, no significant difference in microbial load was observed between the different concentrations of each chemical used (p>0.05). The application of combinations of chemical immersion treatments (LA3%+AA3% and LA3%+CA3%) did not result in further significant reductions in microbial populations when compared to single chemical treatments (P<0.05). Assessment of color changes in meat following the application of chemical immersion treatments indicated that using AA or CA at either concentration and LA at 5% led to an increase in the ΔE* value of >3 immediately after treatment and after 24h storage. The remaining treatments did not result in significant changes to the color of raw beef. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Activation of Aluminum as an Effective Reducing Agent by Pitting Corrosion for Wet-chemical Synthesis

    PubMed Central

    Li, Wei; Cochell, Thomas; Manthiram, Arumugam

    2013-01-01

    Metallic aluminum (Al) is of interest as a reducing agent because of its low standard reduction potential. However, its surface is invariably covered with a dense aluminum oxide film, which prevents its effective use as a reducing agent in wet-chemical synthesis. Pitting corrosion, known as an undesired reaction destroying Al and is enhanced by anions such as F−, Cl−, and Br− in aqueous solutions, is applied here for the first time to activate Al as a reducing agent for wet-chemical synthesis of a diverse array of metals and alloys. Specifically, we demonstrate the synthesis of highly dispersed palladium nanoparticles on carbon black with stabilizers and the intermetallic Cu2Sb/C, which are promising candidates, respectively, for fuel cell catalysts and lithium-ion battery anodes. Atomic hydrogen, an intermediate during the pitting corrosion of Al in protonic solvents (e.g., water and ethylene glycol), is validated as the actual reducing agent. PMID:23390579

  15. Goodness of fit to a mathematical model for Drosophila sleep behavior is reduced in hyposomnolent mutants

    PubMed Central

    2016-01-01

    The conserved nature of sleep in Drosophila has allowed the fruit fly to emerge in the last decade as a powerful model organism in which to study sleep. Recent sleep studies in Drosophila have focused on the discovery and characterization of hyposomnolent mutants. One common feature of these animals is a change in sleep architecture: sleep bout count tends to be greater, and sleep bout length lower, in hyposomnolent mutants. I propose a mathematical model, produced by least-squares nonlinear regression to fit the form Y = aX∧b, which can explain sleep behavior in the healthy animal as well as previously-reported changes in total sleep and sleep architecture in hyposomnolent mutants. This model, fit to sleep data, yields coefficient of determination R squared, which describes goodness of fit. R squared is lower, as compared to control, in hyposomnolent mutants insomniac and fumin. My findings raise the possibility that low R squared is a feature of all hyposomnolent mutants, not just insomniac and fumin. If this were the case, R squared could emerge as a novel means by which sleep researchers might assess sleep dysfunction. PMID:27004144

  16. Mathematical Modeling of the Effectiveness of Facemasks in Reducing the Spread of Novel Influenza A (H1N1)

    PubMed Central

    Tracht, Samantha M.; Del Valle, Sara Y.; Hyman, James M.

    2010-01-01

    On June 11, 2009, the World Health Organization declared the outbreak of novel influenza A (H1N1) a pandemic. With limited supplies of antivirals and vaccines, countries and individuals are looking at other ways to reduce the spread of pandemic (H1N1) 2009, particularly options that are cost effective and relatively easy to implement. Recent experiences with the 2003 SARS and 2009 H1N1 epidemics have shown that people are willing to wear facemasks to protect themselves against infection; however, little research has been done to quantify the impact of using facemasks in reducing the spread of disease. We construct and analyze a mathematical model for a population in which some people wear facemasks during the pandemic and quantify impact of these masks on the spread of influenza. To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks. The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%. We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009. PMID:20161764

  17. Reducing aquatic hazards of industrial chemicals: probabilistic assessment of sustainable molecular design guidelines.

    PubMed

    Connors, Kristin A; Voutchkova-Kostal, Adelina M; Kostal, Jakub; Anastas, Paul; Zimmerman, Julie B; Brooks, Bryan W

    2014-08-01

    Basic toxicological information is lacking for the majority of industrial chemicals. In addition to increasing empirical toxicity data through additional testing, prospective computational approaches to drug development aim to serve as a rational basis for the design of chemicals with reduced toxicity. Recent work has resulted in the derivation of a "rule of 2," wherein chemicals with an octanol-water partition coefficient (log P) less than 2 and a difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital (ΔE) greater than 9 (log P<2 and ΔE >9 eV) are predicted to be 4 to 5 times less likely to elicit acute or chronic toxicity to model aquatic organisms. The present study examines potential reduction of aquatic toxicity hazards from industrial chemicals if these 2 molecular design guidelines were employed. Probabilistic hazard assessment approaches were used to model the likelihood of encountering industrial chemicals exceeding toxicological categories of concern both with and without the rule of 2. Modeling predicted that utilization of these molecular design guidelines for log P and ΔE would appreciably decrease the number of chemicals that would be designated to be of "high" and "very high" concern for acute and chronic toxicity to standard model aquatic organisms and end points as defined by the US Environmental Protection Agency. For example, 14.5% of chemicals were categorized as having high and very high acute toxicity to the fathead minnow model, whereas only 3.3% of chemicals conforming to the design guidelines were predicted to be in these categories. Considerations of specific chemical classes (e.g., aldehydes), chemical attributes (e.g., ionization), and adverse outcome pathways in representative species (e.g., receptor-mediated responses) could be used to derive future property guidelines for broader classes of contaminants.

  18. MATHEMATICAL MODEL OF METABOLIC PATHWAYS OF STEROIDOGENESIS TO PREDICT MOLECULAR RESPONSE FOR ENDOCRINE DISRUPTING CHEMICALS.

    EPA Science Inventory

    There is increasing evidence that exposure to endocrine disrupting chemicals (EDCs) in the environment can induce adverse effects on reproduction and development in both humans and wildlife, mediated through hormonal disturbances.

  19. MATHEMATICAL MODEL OF METABOLIC PATHWAYS OF STEROIDOGENESIS TO PREDICT MOLECULAR RESPONSE FOR ENDOCRINE DISRUPTING CHEMICALS.

    EPA Science Inventory

    There is increasing evidence that exposure to endocrine disrupting chemicals (EDCs) in the environment can induce adverse effects on reproduction and development in both humans and wildlife, mediated through hormonal disturbances.

  20. Optimum resource allocation to reduce HIV incidence across sub-Saharan Africa: a mathematical modelling study.

    PubMed

    McGillen, Jessica B; Anderson, Sarah-Jane; Dybul, Mark R; Hallett, Timothy B

    2016-09-01

    Advances in HIV prevention methods offer promise to accelerate declines in incidence, but how these methods can be deployed to have the best effect on the heterogeneous landscape and drivers of the pandemic remains unclear. We postulated that use of epidemic heterogeneity to inform the allocation of resources for combination HIV prevention could enhance the impact of HIV funding across sub-Saharan Africa. We developed a compartmental mathematical model of HIV transmission and disease progression by risk group to subnational resolution in 18 countries, capturing 80% of the adult HIV burden in sub-Saharan Africa. Adults aged 15-49 years were grouped by risk of HIV acquisition and transmission, and those older than 50 years were assumed to have negligible risk. For each top-level administrative division, we calibrated the model to historical data for HIV prevalence, sexual behaviours, treatment scale-up, and demographics. We then evaluated four strategies for allocation of prevention funding over a 15 year period from 2016 to 2030, which exploited epidemic differences between subnational regions to varying degrees. For a $US20 billion representative expenditure over the 15 year period, scale-up of prevention along present funding channels could avert 5·3 million infections relative to no scale-up. Prioritisation of key populations could avert 3·7 million more infections than present funding channels, and additional prioritisation by within-country geography could avert 400 000 more infections. Removal of national constraints could avert a further 600 000 infections. Risk prioritisation has greater marginal impact than geographical prioritisation across multiple expenditure levels. However, targeting by both risk and geography is best for total impact and could achieve gains of up to three times more than present channels. A shift from the present pattern to the optimum pattern would rebalance resources towards more cost-effective interventions and emerging

  1. Mathematical Characterization of Protein Sequences Using Patterns as Chemical Group Combinations of Amino Acids

    PubMed Central

    Choudhury, Pabitra Pal; Jana, Siddhartha Sankar

    2016-01-01

    Comparison of amino acid sequence similarity is the fundamental concept behind the protein phylogenetic tree formation. By virtue of this method, we can explain the evolutionary relationships, but further explanations are not possible unless sequences are studied through the chemical nature of individual amino acids. Here we develop a new methodology to characterize the protein sequences on the basis of the chemical nature of the amino acids. We design various algorithms for studying the variation of chemical group transitions and various chemical group combinations as patterns in the protein sequences. The amino acid sequence of conventional myosin II head domain of 14 family members are taken to illustrate this new approach. We find two blocks of maximum length 6 aa as ‘FPKATD’ and ‘Y/FTNEKL’ without repeating the same chemical nature and one block of maximum length 20 aa with the repetition of chemical nature which are common among all 14 members. We also check commonality with another motor protein sub-family kinesin, KIF1A. Based on our analysis we find a common block of length 8 aa both in myosin II and KIF1A. This motif is located in the neck linker region which could be responsible for the generation of mechanical force, enabling us to find the unique blocks which remain chemically conserved across the family. We also validate our methodology with different protein families such as MYOI, Myosin light chain kinase (MLCK) and Rho-associated protein kinase (ROCK), Na+/K+-ATPase and Ca2+-ATPase. Altogether, our studies provide a new methodology for investigating the conserved amino acids’ pattern in different proteins. PMID:27930687

  2. Mathematical Characterization of Protein Sequences Using Patterns as Chemical Group Combinations of Amino Acids.

    PubMed

    Das, Jayanta Kumar; Das, Provas; Ray, Korak Kumar; Choudhury, Pabitra Pal; Jana, Siddhartha Sankar

    2016-01-01

    Comparison of amino acid sequence similarity is the fundamental concept behind the protein phylogenetic tree formation. By virtue of this method, we can explain the evolutionary relationships, but further explanations are not possible unless sequences are studied through the chemical nature of individual amino acids. Here we develop a new methodology to characterize the protein sequences on the basis of the chemical nature of the amino acids. We design various algorithms for studying the variation of chemical group transitions and various chemical group combinations as patterns in the protein sequences. The amino acid sequence of conventional myosin II head domain of 14 family members are taken to illustrate this new approach. We find two blocks of maximum length 6 aa as 'FPKATD' and 'Y/FTNEKL' without repeating the same chemical nature and one block of maximum length 20 aa with the repetition of chemical nature which are common among all 14 members. We also check commonality with another motor protein sub-family kinesin, KIF1A. Based on our analysis we find a common block of length 8 aa both in myosin II and KIF1A. This motif is located in the neck linker region which could be responsible for the generation of mechanical force, enabling us to find the unique blocks which remain chemically conserved across the family. We also validate our methodology with different protein families such as MYOI, Myosin light chain kinase (MLCK) and Rho-associated protein kinase (ROCK), Na+/K+-ATPase and Ca2+-ATPase. Altogether, our studies provide a new methodology for investigating the conserved amino acids' pattern in different proteins.

  3. Reduced and simplified chemical kinetics for air dissociation using Computational Singular Perturbation

    NASA Technical Reports Server (NTRS)

    Goussis, D. A.; Lam, S. H.; Gnoffo, P. A.

    1990-01-01

    The Computational Singular Perturbation CSP methods is employed (1) in the modeling of a homogeneous isothermal reacting system and (2) in the numerical simulation of the chemical reactions in a hypersonic flowfield. Reduced and simplified mechanisms are constructed. The solutions obtained on the basis of these approximate mechanisms are shown to be in very good agreement with the exact solution based on the full mechanism. Physically meaningful approximations are derived. It is demonstrated that the deduction of these approximations from CSP is independent of the complexity of the problem and requires no intuition or experience in chemical kinetics.

  4. Low-dimensional manifolds and reduced chemical models for tropospheric chemistry simulations

    NASA Astrophysics Data System (ADS)

    Lowe, Richard; Tomlin, Alison

    The chemical component of a reactive pollution dispersion model often consumes much of the total computational effort involved. If savings can be made in the calculation of the chemical sub-model without significant loss of accuracy then higher resolution can be afforded in the spatial domain leading to better overall solution accuracy. The usual approach to reducing chemical models is by combining species with similar reactivities into single variables. Compact representations of atmospheric chemical mechanisms can be found of the order of 30-100 species. Dynamical systems analysis however shows that the long-term behaviour of chemical systems is usually restricted to much lower-dimensional manifolds in the total species space, due to many of the fast time-scales quickly reaching local equilibrium. This suggests that if appropriate representations can be found, further reductions can be made in the number of variables required to represent tropospheric chemistry. This paper will demonstrate using time-scale analysis that the intrinsic dimension of a typical tropospheric chemical model is low (varying between 2 and 9) and therefore by using a lower-dimensional representation of the chemistry, savings can be made in terms of the number of equations which need to be solved in the chemical sub-model of a dispersion code. An alternative method for chemical modelling will be described which uses simple difference equations rather than the solution of differential rate equations; a technique called repro-modelling. This technique defines difference equations representing species concentrations as functions of concentrations at previous time-points and important parameters, by fitting orthonormal polynomial functions to large data sets. The use of such fitted algebraic representations makes the repeated chemical kinetic simulations used in reactive dispersion codes more efficient. The paper will present a dimensional analysis of a reduced version of the Carbon-Bond scheme

  5. Mathematical and numerical modelling of fractional crystallization coupled with chemical exchanges and differential magma-solid transport in magma chambers

    NASA Astrophysics Data System (ADS)

    Lakhssassi, Morad; Guy, Bernard; Cottin, Jean-Yves; Touboul, Eric

    2010-05-01

    The knowledge of the chemical evolution of magmas is a major concern in geochemistry and petrology. The jumps (or discontinuities) of chemical composition observed in volcanic series from the same province are also the subject of many studies. In particular the phenomenon of "Daly gap" (Daly 1910, 1925), the name given to the jump in chemical composition between the mafic rocks (basalt) and felsic rocks (trachyte, rhyolite, phonolite), corresponding to the absence or scarcity of rocks of intermediate composition (andesite), in both ocean and continental series. Some authors explain these compositional jumps thanks to the intervention of various geological phenomena which follow in time. For example, when a magma chamber turns from a closed to an open system, the lava of a specific composition is ejected to the surface, favoring the rise of the lightest, the most volatile-rich and the less sticky magmas to the surface of the earth (Geist et al., 1995, Thompson et al., 2001). The various explanations offered, although they agree satisfactorily with the natural data, most often lead us away from basic phenomena of melting / solidification, relative migration and chemical equilibrium between solid and liquid and involve various additional phenomena. In our study, we propose a numerical modelling of the crystallization of a closed magma chamber. The physical and mathematical model distinguishes three main classes of processes occurring simultaneously: - heat transfer and solidification, - relative migration between the solid and the liquid magma, - chemical reactions between the two (solid and liquid) phases. Writing the partial differential equations with dimensionless numbers makes two parameters appear, they express the respective ratios of the solidification velocity on the transport velocity, and the kinetics of chemical exchange on the transport velocity. The speed of relative movement between the solid and the liquid, the solidification velocity and the chemical

  6. Mathematical Analysis of Space Radiator Segmenting for Increased Reliability and Reduced Mass

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2001-01-01

    Spacecraft for long duration deep space missions will need to be designed to survive micrometeoroid bombardment of their surfaces some of which may actually be punctured. To avoid loss of the entire mission the damage due to such punctures must be limited to small, localized areas. This is especially true for power system radiators, which necessarily feature large surface areas to reject heat at relatively low temperature to the space environment by thermal radiation. It may be intuitively obvious that if a space radiator is composed of a large number of independently operating segments, such as heat pipes, a random micrometeoroid puncture will result only in the loss of the punctured segment, and not the entire radiator. Due to the redundancy achieved by independently operating segments, the wall thickness and consequently the weight of such segments can be drastically reduced. Probability theory is used to estimate the magnitude of such weight reductions as the number of segments is increased. An analysis of relevant parameter values required for minimum mass segmented radiators is also included.

  7. Reducing health risk assigned to organic emissions from a chemical weapons incinerator.

    PubMed

    Laman, David M; Weiler, B Douglas; Skeen, Rodney S

    2013-03-01

    Organic emissions from a chemical weapons incinerator have been characterized with an improved set of analytical methods to reduce the human health risk assigned to operations of the facility. A gas chromatography/mass selective detection method with substantially reduced detection limits has been used in conjunction with scanning electron microscopy/energy dispersive X-ray spectrometry and Fourier transform infrared microscopy to improve the speciation of semi-volatile and non-volatile organics emitted from the incinerator. The reduced detection limits have allowed a significant reduction in the assumed polycyclic aromatic hydrocarbon (PAH) and aminobiphenyl (ABP) emission rates used as inputs to the human health risk assessment for the incinerator. A mean factor of 17 decrease in assigned human health risk is realized for six common local exposure scenarios as a result of the reduced PAH and ABP detection limits.

  8. A mathematical basis for plant patterning derived from physico-chemical phenomena.

    PubMed

    Beleyur, Thejasvi; Abdul Kareem, Valiya Kadavu; Shaji, Anil; Prasad, Kalika

    2013-04-01

    The position of leaves and flowers along the stem axis generates a specific pattern, known as phyllotaxis. A growing body of evidence emerging from recent computational modeling and experimental studies suggests that regulators controlling phyllotaxis are chemical, e.g. the plant growth hormone auxin and its dynamic accumulation pattern by polar auxin transport, and physical, e.g. mechanical properties of the cell. Here we present comprehensive views on how chemical and physical properties of cells regulate the pattern of leaf initiation. We further compare different computational modeling studies to understand their scope in reproducing the observed patterns. Despite a plethora of experimental studies on phyllotaxis, understanding of molecular mechanisms of pattern initiation in plants remains fragmentary. Live imaging of growth dynamics and physicochemical properties at the shoot apex of mutants displaying stable changes from one pattern to another should provide mechanistic insights into organ initiation patterns. Copyright © 2013 WILEY Periodicals, Inc.

  9. Reducing levels of toxic chemicals in cigarette smoke: a new Healthy People 2010 objective.

    PubMed

    Richter, Patricia; Pechacek, Terry; Swahn, Monica; Wagman, Victoria

    2008-01-01

    We developed and implemented a national surveillance system to monitor and reduce the levels of toxicchemicals in tobacco smoke. A developmental Healthy People 2010 (HP 2010) objective was revised to report on levels of three categories of chemicals--tobacco-specific nitrosamines, polyaromatic hydrocarbons, and volatile organic compounds--in the smoke of leading U.S. cigarette brands. Unit-based sales-weighted average levels were calculated for each chemical category. The target for the new HP 2010 objective is a 10% reduction in unit-based sales-weighted average levels of each chemical category. The Centers for Disease Control and Prevention provided the baseline, target data, and laboratory analyses. A national data source, national baseline data, and target were presented to the Healthy People Steering Committee during 2005 Midcourse Review. Approval of the revised objective initiated the surveillance of three major classes of toxic chemicals in cigarette smoke. The approved objective provides a feasible, innovative approach for monitoring and supporting measurable population-based reductions in levels of toxic and carcinogenic chemicals in tobacco smoke.

  10. Balancing Chemical Reactions With Matrix Methods and Computer Assistance. Applications of Linear Algebra to Chemistry. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Unit 339.

    ERIC Educational Resources Information Center

    Grimaldi, Ralph P.

    This material was developed to provide an application of matrix mathematics in chemistry, and to show the concepts of linear independence and dependence in vector spaces of dimensions greater than three in a concrete setting. The techniques presented are not intended to be considered as replacements for such chemical methods as oxidation-reduction…

  11. Reactive chemical transport in ground-water hydrology: Challenges to mathematical modeling

    SciTech Connect

    Narasimhan, T.N.; Apps, J.A.

    1990-07-01

    For a long time, earth scientists have qualitatively recognized that mineral assemblages in soils and rocks conform to established principles of chemistry. In the early 1960's geochemists began systematizing this knowledge by developing quantitative thermodynamic models based on equilibrium considerations. These models have since been coupled with advective-dispersive-diffusive transport models, already developed by ground-water hydrologists. Spurred by a need for handling difficult environmental issues related to ground-water contamination, these models are being improved, refined and applied to realistic problems of interest. There is little doubt that these models will play an important role in solving important problems of engineering as well as science over the coming years. Even as these models are being used practically, there is scope for their improvement and many challenges lie ahead. In addition to improving the conceptual basis of the governing equations, much remains to be done to incorporate kinetic processes and biological mediation into extant chemical equilibrium models. Much also remains to be learned about the limits to which model predictability can be reasonably taken. The purpose of this paper is to broadly assess the current status of knowledge in modeling reactive chemical transport and to identify the challenges that lie ahead.

  12. Method for Producing Chemically Bonded Phosphate Ceramics and for Stabilizing Contaminants Encapsulated therein Utilizing Reducing Agents

    SciTech Connect

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

    1999-05-05

    Known phosphate ceramic formulations are improved and the ability to produce iron-based phosphate ceramic systems is enabled by the addition of an oxidizing or reducing step during the acid-base reactions that form the phosphate ceramic products. The additives allow control of the rate of the acid-base reactions and concomitant heat generation. In an alternate embodiment, waste containing metal anions is stabilized in phosphate ceramic products by the addition of a reducing agent to the phosphate ceramic mixture. The reduced metal ions are more stable and/or reactive with the phosphate ions, resulting in the formation of insoluble metal species within the phosphate ceramic matrix, such that the resulting chemically bonded phosphate ceramic product has greater leach resistance.

  13. Method for producing chemically bonded phosphate ceramics and for stabilizing contaminants encapsulated therein utilizing reducing agents

    DOEpatents

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

    2000-01-01

    Known phosphate ceramic formulations are improved and the ability to produce iron-based phosphate ceramic systems is enabled by the addition of an oxidizing or reducing step during the acid-base reactions that form the phosphate ceramic products. The additives allow control of the rate of the acid-base reactions and concomitant heat generation. In an alternate embodiment, waste containing metal anions are stabilized in phosphate ceramic products by the addition of a reducing agent to the phosphate ceramic mixture. The reduced metal ions are more stable and/or reactive with the phosphate ions, resulting in the formation of insoluble metal species within the phosphate ceramic matrix, such that the resulting chemically bonded phosphate ceramic product has greater leach resistance.

  14. Rational application of chemicals in response to oil spills may reduce environmental damage.

    PubMed

    Tamis, Jacqueline E; Jongbloed, Ruud H; Karman, Chris C; Koops, Wierd; Murk, Albertinka J

    2012-04-01

    Oil spills, for example those due to tanker collisions and groundings or platform accidents, can have huge adverse impacts on marine systems. The impact of an oil spill at sea depends on a number of factors, such as spill volume, type of oil spilled, weather conditions, and proximity to environmentally, economically, or socially sensitive areas. Oil spilled at sea threatens marine organisms, whole ecosystems, and economic resources in the immediate vicinity, such as fisheries, aquaculture, recreation, and tourism. Adequate response to any oil spill to minimize damage is therefore of great importance. The common response to an oil spill is to remove all visible oil from the water surface, either mechanically or by using chemicals to disperse the oil into the water column to biodegrade. This is not always the most suitable response to an oil spill, as the chemical application itself may also have adverse effects, or no response may be needed. In this article we discuss advantages and disadvantages of using chemical treatments to reduce the impact of an oil spill in relation to the conditions of the spill. The main characteristics of chemical treatment agents are discussed and presented within the context of a basic decision support scheme.

  15. Dissolution of synthetic uranium dibutyl phosphate deposits in oxidizing and reducing chemical formulations.

    PubMed

    Rufus, A L; Sathyaseelan, V S; Narasimhan, S V; Velmurugan, S

    2013-06-15

    Permanganate and nitrilotriacetic acid (NTA) based dilute chemical formulations were evaluated for the dissolution of uranium dibutyl phosphate (U-DBP), a compound that deposits over the surfaces of nuclear reprocessing plants and waste storage tanks. A combination of an acidic, oxidizing treatment (nitric acid with permanganate) followed by reducing treatment (NTA based formulation) efficiently dissolved the U-DBP deposits. The dissolution isotherm of U-DBP in its as precipitated form followed a logarithmic fit. The same chemical treatment was also effective in dissolving U-DBP coated on the surface of 304-stainless steel, while resulting in minimal corrosion of the stainless steel substrate material. Investigation of uranium recovery from the resulting decontamination solutions by ion exchange with a bed of mixed anion and cation resins showed quantitative removal of uranium. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Spraying chicken skin with selected chemicals to reduce attached Salmonella typhimurium.

    PubMed

    Xiong, H; Li, Y; Slavik, M F; Walker, J T

    1998-03-01

    Aqueous solutions of 5% and 10% trisodium phosphate (TSP), 0.1% and 0.5% cetylpyridinium chloride (CPC), 1% and 2% lactic acid (LA), and 0.1% and 0.5% grapefruit seed extract (DF-100) were evaluated in prechill spraying for reducing Salmonella typhimurium attached on chicken skins. Chicken skins were inoculated with S. typhimurium and then sprayed with the selected chemical solutions for 30 sec at 206 kPa and 20 degrees C. After chemical spraying, the skins were rinsed by spraying tap water for 30 sec. Each skin was stomached in buffered peptone water (BPW) for 1 min. The stomaching water was then diluted serially, inoculated onto both xylose lysine tergitol (XLT4) agar and Aerobic Plate Count (APC) Petrifilm, and incubated for 24 hr at 37 degrees C. The results showed that the numbers of Salmonella on the chicken skins after the chemical spraying were significantly lower than those without spray (P < 0.05). The CPC reduced Salmonella by 1.5 to 1.9 log10. TSP resulted in a 2.1 to 2.2 log10 reduction of Salmonella and DF-100 produced a 1.6 to 1.8 log10 reduction of Salmonella. The LA had a number of Salmonella with a 2.2 log10 reduction. The 0.5% CPC resulted a significantly greater reduction in Salmonella than 0.1% CPC. There were no significant differences in Salmonella reduction between different concentrations of the other three chemicals.

  17. Advantages of isothermal titration calorimetry for xylanase kinetics in comparison to chemical-reducing-end assays.

    PubMed

    Baumann, Martin J; Murphy, Leigh; Lei, Nina; Krogh, Kristian B R M; Borch, Kim; Westh, Peter

    2011-03-01

    In lignocellulosic raw materials for biomass conversion, hemicelluloses constitute a substantial fraction, with xylan being the primary part. Although many pretreatments reduce the amount or change the distribution of xylan, it is important to degrade residual xylan so as to improve the overall yield. Typically, xylanase reaction rates are measured in stopped assays by chemical quantification of the reducing ends. With isothermal titration calorimetry (ITC), the heat flow of the hydrolysis can be measured in continuous fashion, with the reaction rate being directly proportional to the heat flow. Reaction enthalpies for carbohydrate hydrolysis are typically below 5kJ/mol, which is the limiting factor for straight forward calorimetric quantification of enzymatic reaction rates using current ITC technology. To increase the apparent reaction enthalpy, we employed a subsequent oxidation of hydrolysis products by carbohydrate oxidase and catalase. Here we show that the coupled assay with carbohydrate oxidase and catalase can be used to measure enzyme kinetics of a GH10 xylanase from Aspergillus aculeatus on birch xylan and wheat arabinoxylan. Results are discussed in the light of a critical analysis of the sensitivity of four chemical-reducing-end quantification methods using well-characterized substrates. 2010 Elsevier Inc. All rights reserved.

  18. Chemical and electrochemical study of fabrics coated with reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Molina, J.; Fernández, J.; del Río, A. I.; Bonastre, J.; Cases, F.

    2013-08-01

    Polyester fabrics coated with reduced graphene oxide (RGO) have been obtained and later characterized by means of chemical and electrochemical techniques. X-ray photoelectron spectroscopy showed a decrease of the oxygen content as well as an increase of the sp2 fraction after chemical reduction of graphene oxide (GO). The electrical conductivity was measured by electrochemical impedance spectroscopy (EIS) and showed a decrease of 5 orders of magnitude in the resistance (Ω) when GO was reduced to RGO. The phase angle also changed from 90° for PES-GO (capacitative behavior) to 0° for RGO coated fabrics (resistive behavior). In general an increase in the number of RGO layers produced an increase of the conductivity of the fabrics. EIS measurements in metal/sample/electrolyte configuration showed better electrocatalytic properties and faster diffusion rate for RGO specimens. Scanning electrochemical microscopy was employed to test the electroactivity of the different fabrics obtained. The sample coated with GO was not conductive since negative feedback was obtained. When GO was reduced to RGO the sample behaved like a conducting material since positive feedback was obtained. Approach curves indicated that the redox mediator had influence on the electrochemical response. The Fe(CN)63-/4- redox mediator produced a higher electrochemical response than Ru(NH3)63+/2+ one.

  19. Mathematical simulation of chlorinated ethene concentration rebound after in situ chemical oxidation.

    PubMed

    Tressler, Adam; Uchrin, Christopher

    2014-01-01

    Permanganates have been used for in situ chemical oxidation (ISCO) projects since the 1990s. Unfortunately, there has been very little research performed on the phenomenon of concentration rebound after ISCO. Most research on ISCO has focused on demonstrating effectiveness, estimating kinetics, or quantifying the effects of reaction products. Only one study has demonstrated that a correlation between concentration rebound and hydrogeological parameters exists. Our study uses a numerical solution to an advection-dispersion-reaction equation to quantify a correlation between the rate of concentration rebound and molecular diffusivity in pure water. It accomplishes this by simulating a variety of sites contaminated with chlorinated ethenes that also had an ISCO with permanganate. Each simulation included advection, two-dimensional dispersion, oxidation, concentration rebound, natural oxidant demand, and retardation. Five sites were suitable for simulation and eight cells were delineated within the five sites. These cells allowed for a variety of soils, contaminants, injection methods (i.e. frequency, depth, mass of oxidant, duration, etc…), time scales, spatial scales, and hydrogeological variables to be examined. A robust correlation (R(2) = 0.92) was identified with a regression analysis between the molecular diffusion coefficient in pure water and the rate of concentration rebound.

  20. Nitroxyl (HNO): A Reduced Form of Nitric Oxide with Distinct Chemical, Pharmacological, and Therapeutic Properties

    PubMed Central

    Shoman, Mai E.; Aly, Omar M.

    2016-01-01

    Nitroxyl (HNO), the one-electron reduced form of nitric oxide (NO), shows a distinct chemical and biological profile from that of NO. HNO is currently being viewed as a vasodilator and positive inotropic agent that can be used as a potential treatment for heart failure. The ability of HNO to react with thiols and thiol containing proteins is largely used to explain the possible biological actions of HNO. Herein, we summarize different aspects related to HNO including HNO donors, chemistry, biology, and methods used for its detection. PMID:26770654

  1. Ammonia gas sensors based on chemically reduced graphene oxide sheets self-assembled on Au electrodes

    NASA Astrophysics Data System (ADS)

    Wang, Yanyan; Zhang, Liling; Hu, Nantao; Wang, Ying; Zhang, Yafei; Zhou, Zhihua; Liu, Yanhua; Shen, Su; Peng, Changsi

    2014-05-01

    We present a useful ammonia gas sensor based on chemically reduced graphene oxide (rGO) sheets by self-assembly technique to create conductive networks between parallel Au electrodes. Negative graphene oxide (GO) sheets with large sizes (>10 μm) can be easily electrostatically attracted onto positive Au electrodes modified with cysteamine hydrochloride in aqueous solution. The assembled GO sheets on Au electrodes can be directly reduced into rGO sheets by hydrazine or pyrrole vapor and consequently provide the sensing devices based on self-assembled rGO sheets. Preliminary results, which have been presented on the detection of ammonia (NH3) gas using this facile and scalable fabrication method for practical devices, suggest that pyrrole-vapor-reduced rGO exhibits much better (more than 2.7 times with the concentration of NH3 at 50 ppm) response to NH3 than that of rGO reduced from hydrazine vapor. Furthermore, this novel gas sensor based on rGO reduced from pyrrole shows excellent responsive repeatability to NH3. Overall, the facile electrostatic self-assembly technique in aqueous solution facilitates device fabrication, the resultant self-assembled rGO-based sensing devices, with miniature, low-cost portable characteristics and outstanding sensing performances, which can ensure potential application in gas sensing fields.

  2. Ammonia gas sensors based on chemically reduced graphene oxide sheets self-assembled on Au electrodes.

    PubMed

    Wang, Yanyan; Zhang, Liling; Hu, Nantao; Wang, Ying; Zhang, Yafei; Zhou, Zhihua; Liu, Yanhua; Shen, Su; Peng, Changsi

    2014-01-01

    We present a useful ammonia gas sensor based on chemically reduced graphene oxide (rGO) sheets by self-assembly technique to create conductive networks between parallel Au electrodes. Negative graphene oxide (GO) sheets with large sizes (>10 μm) can be easily electrostatically attracted onto positive Au electrodes modified with cysteamine hydrochloride in aqueous solution. The assembled GO sheets on Au electrodes can be directly reduced into rGO sheets by hydrazine or pyrrole vapor and consequently provide the sensing devices based on self-assembled rGO sheets. Preliminary results, which have been presented on the detection of ammonia (NH3) gas using this facile and scalable fabrication method for practical devices, suggest that pyrrole-vapor-reduced rGO exhibits much better (more than 2.7 times with the concentration of NH3 at 50 ppm) response to NH3 than that of rGO reduced from hydrazine vapor. Furthermore, this novel gas sensor based on rGO reduced from pyrrole shows excellent responsive repeatability to NH3. Overall, the facile electrostatic self-assembly technique in aqueous solution facilitates device fabrication, the resultant self-assembled rGO-based sensing devices, with miniature, low-cost portable characteristics and outstanding sensing performances, which can ensure potential application in gas sensing fields.

  3. Ammonia gas sensors based on chemically reduced graphene oxide sheets self-assembled on Au electrodes

    PubMed Central

    2014-01-01

    We present a useful ammonia gas sensor based on chemically reduced graphene oxide (rGO) sheets by self-assembly technique to create conductive networks between parallel Au electrodes. Negative graphene oxide (GO) sheets with large sizes (>10 μm) can be easily electrostatically attracted onto positive Au electrodes modified with cysteamine hydrochloride in aqueous solution. The assembled GO sheets on Au electrodes can be directly reduced into rGO sheets by hydrazine or pyrrole vapor and consequently provide the sensing devices based on self-assembled rGO sheets. Preliminary results, which have been presented on the detection of ammonia (NH3) gas using this facile and scalable fabrication method for practical devices, suggest that pyrrole-vapor-reduced rGO exhibits much better (more than 2.7 times with the concentration of NH3 at 50 ppm) response to NH3 than that of rGO reduced from hydrazine vapor. Furthermore, this novel gas sensor based on rGO reduced from pyrrole shows excellent responsive repeatability to NH3. Overall, the facile electrostatic self-assembly technique in aqueous solution facilitates device fabrication, the resultant self-assembled rGO-based sensing devices, with miniature, low-cost portable characteristics and outstanding sensing performances, which can ensure potential application in gas sensing fields. PMID:24917701

  4. Imaging Chemical Aggregation of Ni/NiO Particles from Reduced NiO-YSZ

    SciTech Connect

    Saraf, Laxmikant V.

    2011-07-20

    Energy dispersive X-ray spectroscopy (EDS) mapping of nickel oxide yttria-stabilized zirconia (NiO-YSZ) was carried out after various hydrogen reducing and methane steam reforming conditions. Nickel aggregation was visualized after methane steam reforming by correlating Ni K{sub {alpha}} map with scanning transmission electron microscopy (STEM) images. From the reduced O K{sub {alpha}} intensities in the Ni K{sub {alpha}} dominated regions after methane steam reforming, NiO reduction in to Ni can be interpreted. From correlation between Zr K{sub {alpha}} and O K{sub {alpha}} maps, high stability of YSZ was also realized. Examples of NiO-YSZ overlapped particles are considered to discuss chemical imaging of a single particle.

  5. Electromagnetic interference shielding properties and mechanisms of chemically reduced graphene aerogels

    NASA Astrophysics Data System (ADS)

    Bi, Shuguang; Zhang, Liying; Mu, Chenzhong; Liu, Ming; Hu, Xiao

    2017-08-01

    Graphene was recently demonstrated to exhibit excellent electromagnetic interference (EMI) shielding performance. In this work, ultralight (∼5.5 mg/cm3) graphene aerogels (GAs) were fabricated through assembling graphene oxide (GO) using freeze-drying followed by a chemical reduction method. The EMI shielding properties and mechanisms of GAs were systematically studied with respect to the intrinsic properties of the reduced graphene oxide (rGO) sheets and the unique porous network. The EMI shielding effectiveness (SE) of GAs was increased from 20.4 to 27.6 dB when the GO was reduced by high concentration of hydrazine vapor. The presence of more sp2 graphitic lattice and free electrons from nitrogen atoms resulted in the enhanced EMI SE. Absorption was the dominant shielding mechanism of GAs. Compressing the highly porous GAs into compact thin films did not change the EMI SE, but shifted the dominant shielding mechanism from absorption to reflection.

  6. Herbivore induction of jasmonic acid and chemical defences reduce photosynthesis in Nicotiana attenuata.

    PubMed

    Nabity, Paul D; Zavala, Jorge A; DeLucia, Evan H

    2013-01-01

    Herbivory initiates a shift in plant metabolism from growth to defence that may reduce fitness in the absence of further herbivory. However, the defence-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. This study characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defences in Nicotiana attenuata to increase understanding of these mechanisms. It was hypothesized that JA-induced defences would immediately reduce the component processes of photosynthesis upon attack and was predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defences. Gas exchange, chlorophyll fluorescence, and thermal spatial patterns were measured together with the production of defence-related metabolites after attack and through recovery. Herbivore damage immediately reduced electron transport and gas exchange in wild-type plants, and gas exchange remained suppressed for several days after attack. The sustained reductions in gas exchange occurred concurrently with increased defence metabolites in wild-type plants, whereas plants lacking JA-induced defences suffered minimal suppression in photosynthesis and no increase in defence metabolite production. This suppression in photosynthesis occurred only after sustained defence signalling and defence chemical mobilization, whereas a short bout of feeding damage only transiently altered components of photosynthesis. It was identified that lipoxygenase signalling interacted with photosynthetic electron transport and that the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting a chemical defence against herbivory and link defence-signalling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner.

  7. The Unfolded Protein Response and Chemical Chaperones Reduce Protein Misfolding and Colitis in Mice

    PubMed Central

    CAO, STEWART SIYAN; ZIMMERMANN, ELLEN M.; CHUANG, BRANDY–MENGCHIEH; SONG, BENBO; NWOKOYE, ANOSIKE; WILKINSON, J. ERBY; EATON, KATHRYN A.; KAUFMAN, RANDAL J.

    2013-01-01

    BACKGROUND & AIMS Endoplasmic reticulum (ER) stress has been associated with development of inflammatory bowel disease. We examined the effects of ER stress–induced chaperone response and the orally active chemical chaperones tauroursodeoxycholate (TUDCA) and 4-phenylbutyrate (PBA), which facilitate protein folding and reduce ER stress, in mice with colitis. METHODS We used dextran sulfate sodium (DSS) to induce colitis in mice that do not express the transcription factor ATF6α or the protein chaperone P58IPK. We examined the effects of TUDCA and PBA in cultured intestinal epithelial cells (IECs); in wild-type, P58IPK−/−, and Atf6α−/− mice with colitis; and in Il10−/− mice. RESULTS P58IPK−/− and Atf6α−/− mice developed more severe colitis following administration of DSS than wild-type mice. IECs from P58IPK−/− mice had excessive ER stress, and apoptotic signaling was activated in IECs from Atf6α−/− mice. Inflammatory stimuli induced ER stress signals in cultured IECs, which were reduced by incubation with TUDCA or PBA. Oral administration of either PBA or TUDCA reduced features of DSS-induced acute and chronic colitis in wild-type mice, the colitis that develops in Il10−/− mice, and DSS-induced colitis in P58IPK−/− and Atf6α−/− mice. Reduced signs of colonic inflammation in these mice were associated with significantly decreased ER stress in colonic epithelial cells. CONCLUSIONS The unfolded protein response induces expression of genes that encode chaperones involved in ER protein folding; these factors prevent induction of colitis in mice. Chemical chaperones such as TUDCA and PBA alleviate different forms of colitis in mice and might be developed for treatment of inflammatory bowel diseases. PMID:23336977

  8. An integrated mathematical model for chemical oxygen demand (COD) removal in moving bed biofilm reactors (MBBR) including predation and hydrolysis.

    PubMed

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-07-01

    An integrated mathematical model is proposed for modelling a moving bed biofilm reactor (MBBR) for removal of chemical oxygen demand (COD) under aerobic conditions. The composite model combines the following: (i) a one-dimensional biofilm model, (ii) a bulk liquid model, and (iii) biological processes in the bulk liquid and biofilm considering the interactions among autotrophic, heterotrophic and predator microorganisms. Depending on the values for the soluble biodegradable COD loading rate (SCLR), the model takes into account a) the hydrolysis of slowly biodegradable compounds in the bulk liquid, and b) the growth of predator microorganisms in the bulk liquid and in the biofilm. The integration of the model and the SCLR allows a general description of the behaviour of COD removal by the MBBR under various conditions. The model is applied for two in-series MBBR wastewater plant from an integrated cellulose and viscose production and accurately describes the experimental concentrations of COD, total suspended solids (TSS), nitrogen and phosphorous obtained during 14 months working at different SCLRs and nutrient dosages. The representation of the microorganism group distribution in the biofilm and in the bulk liquid allow for verification of the presence of predator microorganisms in the second reactor under some operational conditions.

  9. Reducing the mechanical action of polishing pressure and abrasive during copper chemical mechanical planarization

    NASA Astrophysics Data System (ADS)

    Mengting, Jiang; Yuling, Liu

    2014-12-01

    Chemical mechanical planarization (CMP) is a critical process in deep sub-micron integrated circuit manufacturing. This study aims to improve the planarization capability of slurry, while minimizing the mechanical action of the pressure and silica abrasive. Through conducting a series of single-factor experiments, the appropriate pressure and the optimum abrasive concentration for the alkaline slurry were confirmed. However, the reduced mechanical action may bring about a decline of the polishing rate, and further resulting in the decrease of throughput. Therefore, we take an approach to compensating for the loss of mechanical action by optimizing the composition of the slurry to enhance the chemical action in the CMP process. So 0.5 wt% abrasive concentration of alkaline slurry for copper polishing was developed, it can achieve planarization efficiently and obtain a wafer surface with no corrosion defect at a reduced pressure of 1.0 psi. The results presented here will contribute to the development of a “softer gentler polishing” technique in the future.

  10. Synthesis of Bulk BC8 Silicon Allotrope by Direct Transformation and Reduced-Pressure Chemical Pathways.

    PubMed

    Kurakevych, Oleksandr O; Le Godec, Yann; Crichton, Wilson A; Guignard, Jérémy; Strobel, Timothy A; Zhang, Haidong; Liu, Hanyu; Coelho Diogo, Cristina; Polian, Alain; Menguy, Nicolas; Juhl, Stephen J; Gervais, Christel

    2016-09-06

    Phase-pure samples of a metastable allotrope of silicon, Si-III or BC8, were synthesized by direct elemental transformation at 14 GPa and ∼900 K and also at significantly reduced pressure in the Na-Si system at 9.5 GPa by quenching from high temperatures ∼1000 K. Pure sintered polycrystalline ingots with dimensions ranging from 0.5 to 2 mm can be easily recovered at ambient conditions. The chemical route also allowed us to decrease the synthetic pressures to as low as 7 GPa, while pressures required for direct phase transition in elemental silicon are significantly higher. In situ control of the synthetic protocol, using synchrotron radiation, allowed us to observe the underlying mechanism of chemical interactions and phase transformations in the Na-Si system. Detailed characterization of Si-III using X-ray diffraction, Raman spectroscopy, (29)Si NMR spectroscopy, and transmission electron microscopy are discussed. These large-volume syntheses at significantly reduced pressures extend the range of possible future bulk characterization methods and applications.

  11. Chemically active reduced graphene oxide with tunable C/O ratios.

    PubMed

    Compton, Owen C; Jain, Bonny; Dikin, Dmitriy A; Abouimrane, Ali; Amine, Khalil; Nguyen, Sonbinh T

    2011-06-28

    Organic dispersions of graphene oxide can be thermally reduced in polar organic solvents under reflux conditions to afford electrically conductive, chemically active reduced graphene oxide (CARGO) with tunable C/O ratios, dependent on the boiling point of the solvent. The reductions are achieved after only 1 h of reflux, and the corresponding C/O ratios do not change upon further thermal treatment. Hydroxyl and carboxyl groups can be removed when the reflux is carried out above 155 °C, while epoxides are removable only when the temperature is higher than 200 °C. The increasing hydrophobic nature of CARGO, as its C/O ratio increases, improves the dispersibility of the nanosheets in a polystyrene matrix, in contrast to the aggregates formed with CARGO having lower C/O ratios. The excellent processability of the obtained CARGO dispersions is demonstrated via free-standing CARGO papers that exhibit tunable electrical conductivity/chemical activity and can be used as lithium-ion battery anodes with enhanced Coulombic efficiency.

  12. Reduced biological control and enhanced chemical pest management in the evolution of fungus farming in ants

    PubMed Central

    Fernández-Marín, Hermógenes; Zimmerman, Jess K.; Nash, David R.; Boomsma, Jacobus J.; Wcislo, William T.

    2009-01-01

    To combat disease, most fungus-growing ants (Attini) use antibiotics from mutualistic bacteria (Pseudonocardia) that are cultured on the ants' exoskeletons and chemical cocktails from exocrine glands, especially the metapleural glands (MG). Previous work has hypothesized that (i) Pseudonocardia antibiotics are narrow-spectrum and control a fungus (Escovopsis) that parasitizes the ants' fungal symbiont, and (ii) MG secretions have broad-spectrum activity and protect ants and brood. We assessed the relative importance of these lines of defence, and their activity spectra, by scoring abundance of visible Pseudonocardia for nine species from five genera and measuring rates of MG grooming after challenging ants with disease agents of differing virulence. Atta and Sericomyrmex have lost or greatly reduced the abundance of visible bacteria. When challenged with diverse disease agents, including Escovopsis, they significantly increased MG grooming rates and expanded the range of targets. By contrast, species of Acromyrmex and Trachymyrmex maintain abundant Pseudonocardia. When challenged, these species had lower MG grooming rates, targeted primarily to brood. More elaborate MG defences and reduced reliance on mutualistic Pseudonocardia are correlated with larger colony size among attine genera, raising questions about the efficacy of managing disease in large societies with chemical cocktails versus bacterial antimicrobial metabolites. PMID:19324734

  13. Ferromagnetism in chemically reduced LiNbO3 and LiTaO3 crystals

    NASA Astrophysics Data System (ADS)

    Yan, Tao; Ye, Ning; Xu, Liuwei; Sang, Yuanhua; Chen, Yanxue; Song, Wei; Long, Xifa; Wang, Jiyang; Liu, Hong

    2016-05-01

    The ferromagnetism of bulk LiNbO3 and LiTaO3 at room temperature was investigated for the first time in the present work. The stoichiometric LiNbO3 is non-magnetic, while congruent LiNbO3 and LiTaO3 show very weak ferromagnetism. After chemical reduction in a mixture of zinc and lithium carbonate powders under flowing nitrogen, the ferromagnetic behavior of each sample became clear, with an increased value of magnetization. The saturation magnetization, the magnetic remanence and the coercive field of reduced congruent LiNbO3 are 7.0  ×  10-3 emu g-1, 0.65  ×  10-3 emu g-1 and 0.050 kOe, respectively. The ferromagnetism of chemically reduced LiNbO3 and LiTaO3 can be explained by considering the intrinsic Li vacancies, the appearance of Nb4+ (or Ta4+) on the surface with non-zero net spin and the oxygen vacancies at the surface.

  14. A reduced chemical kinetic model for IC engine combustion simulations with primary reference fuels

    SciTech Connect

    Ra, Youngchul; Reitz, Rolf D.

    2008-12-15

    A reduced chemical kinetic mechanism for the oxidation of primary reference fuel (PRF) has been developed and applied to model internal combustion engines. Starting from an existing reduced reaction mechanism for n-heptane oxidation, a new reduced n-heptane mechanism was generated by including an additional five species and their relevant reactions, by updating the reaction rate constants of several reactions pertaining to oxidation of carbon monoxide and hydrogen, and by optimizing reaction rate constants of selected reactions. Using a similar approach, a reduced mechanism for iso-octane oxidation was built and combined with the n-heptane mechanism to form a PRF mechanism. The final version of the PRF mechanism consists of 41 species and 130 reactions. Validation of the present PRF mechanism was performed with measurements from shock tube tests, and HCCI and direct injection engine experiments available in the literature. The results show that the present PRF mechanism gives reliable performance for combustion predictions, as well as computational efficiency improvements for multidimensional CFD simulations. (author)

  15. Reduced chemical warfare agent sorption in polyurethane-painted surfaces via plasma-enhanced chemical vapor deposition of perfluoroalkanes.

    PubMed

    Gordon, Wesley O; Peterson, Gregory W; Durke, Erin M

    2015-04-01

    Perfluoralkalation via plasma chemical vapor deposition has been used to improve hydrophobicity of surfaces. We have investigated this technique to improve the resistance of commercial polyurethane coatings to chemicals, such as chemical warfare agents. The reported results indicate the surface treatment minimizes the spread of agent droplets and the sorption of agent into the coating. The improvement in resistance is likely due to reduction of the coating's surface free energy via fluorine incorporation, but may also have contributing effects from surface morphology changes. The data indicates that plasma-based surface modifications may have utility in improving chemical resistance of commercial coatings.

  16. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface

    SciTech Connect

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; Crumlin, Ethan J.; Yildiz, Bilge

    2016-06-13

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO 3 ) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H 2 O and CO 2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, Sr La ') by the positively charged oxygen vacancies (V $••\\atop{o}$) enriched at the surface. Here we show that reducing the surface V $••\\atop{o}$ concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O 2 molecules. We take La 0.8 Sr 0.2 CoO 3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of V $••\\atop{o}$ and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a 'volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss.

  17. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; Crumlin, Ethan J.; Yildiz, Bilge

    2016-09-01

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO3) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H2O and CO2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, ) by the positively charged oxygen vacancies () enriched at the surface. Here we show that reducing the surface concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O2 molecules. We take La0.8Sr0.2CoO3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a `volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss.

  18. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface.

    PubMed

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; Crumlin, Ethan J; Yildiz, Bilge

    2016-09-01

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO3) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H2O and CO2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, ) by the positively charged oxygen vacancies () enriched at the surface. Here we show that reducing the surface concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O2 molecules. We take La0.8Sr0.2CoO3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a 'volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss.

  19. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface

    DOE PAGES

    Tsvetkov, Nikolai; Lu, Qiyang; Sun, Lixin; ...

    2016-06-13

    Segregation and phase separation of aliovalent dopants on perovskite oxide (ABO 3 ) surfaces are detrimental to the performance of energy conversion systems such as solid oxide fuel/electrolysis cells and catalysts for thermochemical H 2 O and CO 2 splitting. One key reason behind the instability of perovskite oxide surfaces is the electrostatic attraction of the negatively charged A-site dopants (for example, Sr La ') by the positively charged oxygen vacancies (Vmore » $$••\\atop{o}$$) enriched at the surface. Here we show that reducing the surface V $$••\\atop{o}$$ concentration improves the oxygen surface exchange kinetics and stability significantly, albeit contrary to the well-established understanding that surface oxygen vacancies facilitate reactions with O 2 molecules. We take La 0.8 Sr 0.2 CoO 3 (LSC) as a model perovskite oxide, and modify its surface with additive cations that are more and less reducible than Co on the B-site of LSC. By using ambient-pressure X-ray absorption and photoelectron spectroscopy, we proved that the dominant role of the less reducible cations is to suppress the enrichment and phase separation of Sr while reducing the concentration of V $$••\\atop{o}$$ and making the LSC more oxidized at its surface. Consequently, we found that these less reducible cations significantly improve stability, with up to 30 times faster oxygen exchange kinetics after 54 h in air at 530 °C achieved by Hf addition onto LSC. Finally, the results revealed a 'volcano' relation between the oxygen exchange kinetics and the oxygen vacancy formation enthalpy of the binary oxides of the additive cations. This volcano relation highlights the existence of an optimum surface oxygen vacancy concentration that balances the gain in oxygen exchange kinetics and the chemical stability loss.« less

  20. Alkaline deoxygenated graphene oxide for supercapacitor applications: An effective green alternative for chemically reduced graphene

    NASA Astrophysics Data System (ADS)

    Perera, Sanjaya D.; Mariano, Ruperto G.; Nijem, Nour; Chabal, Yves; Ferraris, John P.; Balkus, Kenneth J.

    2012-10-01

    Graphene is a promising electrode material for energy storage applications. The most successful method for preparing graphene from graphite involves the oxidation of graphite to graphene oxide (GO) and reduction back to graphene. Even though different chemical and thermal methods have been developed to reduce GO to graphene, the use of less toxic materials to generate graphene still remains a challenge. In this study we developed a facile one-pot synthesis of deoxygenated graphene (hGO) via alkaline hydrothermal process, which exhibits similar properties to the graphene obtained via hydrazine reduction (i.e. the same degree of deoxygenation found in hydrazine reduced GO). Moreover, the hGO formed freestanding, binder-free paper electrodes for supercapacitors. Coin cell type (CR2032) symmetric supercapacitors were assembled using the hGO electrodes. Electrochemical characterization of hGO was carried out using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and ethylmethylimidazolium bis-(trifluoromethanesulfonyl)imide (EMITFSI) electrolytes. The results for the hGO electrodes were compared with the hydrazine reduced GO (rGO) electrode. The hGO electrode exhibits a energy density of 20 W h kg-1 and 50 W h kg-1 in LiTFSI and EMITFSI respectively, while delivering a maximum power density of 11 kW kg-1 and 14.7 kW kg-1 in LiTFSI and EMITFSI, respectively.

  1. Real time control for reduced aeration and chemical consumption: a full scale study.

    PubMed

    Thornton, A; Sunner, N; Haeck, M

    2010-01-01

    The use of the activated sludge process (ASP) for the nitrification/denitrification of wastewaters is commonplace throughout the UK and many other parts of the industrial world. Associated with this process are significant costs arising from aeration requirements and for selected sites, the need to provide an external carbon source. These costs can constitute up to of 50% of the total running cost of the whole plant and as such, any effort to reduce them could realise significant benefits. This paper investigates the use of real time control (RTC) using online sensors and control algorithms to optimise the operation of the ASP, leading to greater efficiency and sustainability. Trials were undertaken at full scale to assess the benefit of such a system at a 250,000 population equivalent (PE) works on the south coast of the UK, using Activated sludge model No.1 (ASM 1) as a basis for the control system. Initial results indicate that it is possible to significantly reduce both aeration and chemical consumption costs whilst still delivering the required effluent quality. Over the trial period the aeration requirements were consistently reduced by 20% whereas, a reduction in methanol consumption of in excess of 50% was observed.

  2. Mesoherbivores reduce net growth and induce chemical resistance in natural seaweed populations.

    PubMed

    Toth, Gunilla B; Karlsson, Malin; Pavia, Henrik

    2007-05-01

    Herbivory on marine macroalgae (seaweeds) in temperate areas is often dominated by relatively small gastropods and crustaceans (mesoherbivores). The effects of these herbivores on the performance of adult seaweeds have so far been almost exclusively investigated under artificial laboratory conditions. Furthermore, several recent laboratory studies with mesoherbivores indicate that inducible chemical resistance may be as common in seaweeds as in vascular plants. However, in order to further explore and test the possible ecological significance of induced chemical resistance in temperate seaweeds, data are needed that address this issue in natural populations. We investigated the effect of grazing by littorinid herbivorous snails (Littorina spp.) on the individual net growth of the brown seaweed Ascophyllum nodosum in natural field populations. Furthermore, the capacity for induced resistance in the seaweeds was assessed by removing herbivores and assaying for relaxation of defences. We found that ambient densities of gastropod herbivores significantly reduced net growth by 45% in natural field populations of A. nodosum. Seaweeds previously exposed to grazing in the field were less consumed by gastropod herbivores in feeding bioassays. Furthermore, the concentration of phlorotannins (polyphenolics), which have been shown to deter gastropod herbivores, was higher in the seaweeds that were exposed to gastropod herbivores in the field. This field study corroborates earlier laboratory experiments and demonstrates that it is important to make sure that the lack of experimental field data on marine mesoherbivory does not lead to rash conclusions about the lack of significant effects of these herbivores on seaweed performance. The results strongly suggest that gastropods exert a significant selection pressure on the evolution of defensive traits in the seaweeds, and that brown seaweeds can respond to attacks by natural densities of these herbivores through increased

  3. Ferromagnetic inks facilitate large scale paper recycling and reduce bleach chemical consumption.

    PubMed

    Zeltner, Martin; Toedtli, Laura M; Hild, Nora; Fuhrer, Roland; Rossier, Michaël; Gerber, Lukas C; Raso, Renzo A; Grass, Robert N; Stark, Wendelin J

    2013-04-23

    Deinking is a fundamental part of paper recycling. As the global paper consumption rises and exceeds even the annual paper production, recycling of this raw material is of high importance. Magnetic ink based on carbon coated magnetic nanoparticles enables an alternative approach to state of the art paper deinking. Magnetic deinking comprises three steps (preselection, washing, and magnetic separation of fibers). Preseparation of printed from nonprinted scraps of paper is feasible and reduces the paper mass which has to be fed into a deinking process. A consecutive washing process removes surficial magnetic ink that can be collected by application of a permanent magnet. Still, printed parts are subjected to a further continuous magnetic deinking step, where magnetic and nonmagnetic paper fibers can be separated. Magnetic deinking of a model print allows recovery of more than 80% of bright fibers without any harsh chemical treatment and the re-collection of more than 82% of magnetic ink.

  4. Ultrafast and sensitive room temperature NH3 gas sensors based on chemically reduced graphene oxide.

    PubMed

    Hu, Nantao; Yang, Zhi; Wang, Yanyan; Zhang, Liling; Wang, Ying; Huang, Xiaolu; Wei, Hao; Wei, Liangmin; Zhang, Yafei

    2014-01-17

    Ultrafast and sensitive room temperature NH3 gas sensors based on chemically reduced graphene oxide (rGO) are demonstrated in this work. rGO, which was prepared via the reduction of graphene oxide by pyrrole, exhibited excellent responsive sensitivity and selectivity to ammonia (NH3) gas. The high sensing performance of these rGO sensors with resistance change as high as 2.4% and response time as fast as 1.4 s was realized when the concentration of NH3 gas was as low as 1 ppb. Furthermore, the rGO sensors could rapidly recover to their initial states with IR illumination. The devices also showed excellent repeatability and selectivity to NH3. These rGO sensors, with low cost, low power, and easy fabrication, as well as scalable properties, showed great potential for ultrasensitive detection of NH3 gas in a wide variety of fields.

  5. A marine sulfate-reducing bacterium producing multiple antibiotics: biological and chemical investigation.

    PubMed

    Zhang, Yi; Mu, Jun; Gu, Xiaojie; Zhao, Chenyan; Wang, Xiaoliang; Xie, Zeping

    2009-07-21

    A marine sulfate-reducing bacterium SRB-22 was isolated by means of the agar shake dilution method and identified as Desulfovibrio desulfuricans by morphological, physiological and biochemical characteristics and 16S rDNA analysis. In the bioassay, its extract showed broad-spectrum antimicrobial activity using the paper disc agar diffusion method. This isolate showed a different antimicrobial profile than either ampicillin or nystatin and was found to produce at least eight antimicrobial components by bioautography. Suitable fermentation conditions for production of the active constituents were determined to be 28 day cultivation at 25 degrees C to 30 degrees C with a 10% inoculation ratio. Under these conditions, the SRB-22 was fermented, extracted and chemically investigated. So far an antimicrobial compound, mono-n-butyl phthalate, and an inactive compound, thymine, have been isolated and characterized.

  6. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    NASA Astrophysics Data System (ADS)

    Chang, Sung-Jin; Hyun, Moon Seop; Myung, Sung; Kang, Min-A.; Yoo, Jung Ho; Lee, Kyoung G.; Choi, Bong Gill; Cho, Youngji; Lee, Gaehang; Park, Tae Jung

    2016-03-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.

  7. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration.

    PubMed

    Chang, Sung-Jin; Hyun, Moon Seop; Myung, Sung; Kang, Min-A; Yoo, Jung Ho; Lee, Kyoung G; Choi, Bong Gill; Cho, Youngji; Lee, Gaehang; Park, Tae Jung

    2016-03-10

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.

  8. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    PubMed Central

    Chang, Sung-Jin; Hyun, Moon Seop; Myung, Sung; Kang, Min-A; Yoo, Jung Ho; Lee, Kyoung G.; Choi, Bong Gill; Cho, Youngji; Lee, Gaehang; Park, Tae Jung

    2016-01-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties. PMID:26961409

  9. Secondary Defense Chemicals in Milkweed Reduce Parasite Infection in Monarch Butterflies, Danaus plexippus.

    PubMed

    Gowler, Camden D; Leon, Kristoffer E; Hunter, Mark D; de Roode, Jacobus C

    2015-06-01

    In tri-trophic systems, herbivores may benefit from their host plants in fighting parasitic infections. Plants can provide parasite resistance in two contrasting ways: either directly, by interfering with the parasite, or indirectly, by increasing herbivore immunity or health. In monarch butterflies, the larval diet of milkweed strongly influences the fitness of a common protozoan parasite. Toxic secondary plant chemicals known as cardenolides correlate strongly with parasite resistance of the host, with greater cardenolide concentrations in the larval diet leading to lower parasite growth. However, milkweed cardenolides may covary with other indices of plant quality including nutrients, and a direct experimental link between cardenolides and parasite performance has not been established. To determine if the anti-parasitic activity of milkweeds is indeed due to secondary chemicals, as opposed to nutrition, we supplemented the diet of infected and uninfected monarch larvae with milkweed latex, which contains cardenolides but no nutrients. Across three experiments, increased dietary cardenolide concentrations reduced parasite growth in infected monarchs, which consequently had longer lifespans. However, uninfected monarchs showed no differences in lifespan across treatments, confirming that cardenolide-containing latex does not increase general health. Our results suggest that cardenolides are a driving force behind plant-derived resistance in this system.

  10. The sulfur-fumigation reduces chemical composition and biological properties of Angelicae Sinensis Radix.

    PubMed

    Zhan, Janis Ya-Xian; Yao, Ping; Bi, Cathy Wen-Chuan; Zheng, Ken Yu-Zhong; Zhang, Wendy Li; Chen, Jian-Ping; Dong, Tina Ting-Xia; Su, Zi-Ren; Tsim, Karl Wah-Keung

    2014-09-25

    Angelica Sinensis Radix (roots of Angelica sinensis; ASR) is a popular herbal supplement in China for promoting blood circulation. Today, sulfur-fumigation is commonly used to treat ASR as a means of pest control; however, the studies of sulfur-fumigation on the safety and efficacy of ASR are very limited. Here, we elucidated the destructive roles of sulfur-fumigation on ASR by chemical and biological assessments. After sulfur-fumigation, the chemicals in ASR were significantly lost. The biological activities of anti-platelet aggregation, induction of NO production and estrogenic properties were compared between the water extracts of non-fumigated and sulfur-fumigated ASR. In all cases, the sulfur-fumigation significantly reduced the biological properties of ASR. In addition, application of water extract deriving from sulfur-fumigated ASR showed toxicity to cultured MCF-7 cells. In order to ensure the safety and to achieve the best therapeutic effect, it is recommended that sulfur-fumigation is an unacceptable approach for processing herbal materials. Copyright © 2014 Elsevier GmbH. All rights reserved.

  11. Toothpastes containing abrasive and chemical whitening agents: efficacy in reducing extrinsic dental staining.

    PubMed

    Soares, Cristina Neves Girao Salgado; Amaral, Flavia Lucisano Botelho do; Mesquita, Marcelo Ferraz; Franca, Fabiana Mantovani Gomes; Basting, Roberta Tarkany; Turssi, Cecilia Pedroso

    2015-01-01

    This in vitro study evaluated the efficacy of toothpastes containing abrasive and chemical whitening agents in reducing the extrinsic discoloration of dental enamel. Sixty slabs of dentin from human teeth were sealed so that only the enamel surface was exposed. The enamel surfaces were photographed for initial color assessment. Staining was performed by immersing the dental slabs in 0.2% chlorhexidine solution for 2 minutes and then in black tea for 60 minutes. This process was repeated 15 times. Photographs were taken at the end of the staining process, and the slabs were divided into 5 groups (n = 12), 3 to be brushed with toothpastes containing chemical whitening agents (2 containing phosphate salts and 1 containing phosphate salts plus hydrogen peroxide) and 2 to represent control groups (ordinary/nonwhitening toothpaste and distilled water). The dental slabs were subjected to mechanical toothbrushing with toothpaste slurry or distilled water, according to each group's specifications. After brushing, more photographs were taken for color analysis. The results showed a significant reduction in luminosity after the staining process in addition to an increase in the colors red and yellow (P < 0.001). After brushing, there was a significant increase in luminosity and a reduction in both red and yellow (P < 0.001). However, there was no observed difference between the changes in color values in dental enamel slabs brushed with whitening toothpastes and the changes found in slabs brushed with ordinary toothpaste. The whitening toothpastes did not outperform an ordinary toothpaste in the removal of extrinsic staining.

  12. Ca2+ Selectivity of a Chemically Modified OmpF with Reduced Pore Volume

    PubMed Central

    Miedema, Henk; Vrouenraets, Maarten; Wierenga, Jenny; Gillespie, Dirk; Eisenberg, Bob; Meijberg, Wim; Nonner, Wolfgang

    2006-01-01

    We studied an E. coli OmpF mutant (LECE) containing both an EEEE-like locus, typical of Ca2+ channels, and an accessible and reactive cysteine. After chemical modification with the cysteine-specific, negatively charged (−1e) reagents MTSES or glutathione, this LECE mutant was tested for Ca2+ versus alkali metal selectivity. Selectivity was measured by conductance and zero-current potential. Conductance measurements showed that glutathione-modified LECE had reduced conductance at Ca2+ mole fractions <10−3. MTSES-modified LECE did not. Apparently, the LECE protein is (somehow) a better Ca2+ chelator after modification with the larger glutathione. Zero-current potential measurements revealed a Ca2+ versus monovalent cation selectivity that was highest in the presence of Li+ and lowest in the presence of Cs+. Our data clearly show that after the binding of Ca2+ the LECE pore (even with the bulky glutathione present) is spacious enough to allow monovalent cations to pass. Theoretical computations based on density functional theory combined with Poisson-Nernst-Planck theory and a reduced pore model suggest a functional separation of ionic pathways in the pore, one that is specific for small and highly charged ions, and one that accepts preferentially large ions, such as Cs+. PMID:16997866

  13. A constrained reduced-dimensionality search algorithm to follow chemical reactions on potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Lankau, Timm; Yu, Chin-Hui

    2013-06-01

    A constrained reduced-dimensionality algorithm can be used to efficiently locate transition states and products in reactions involving conformational changes. The search path (SP) is constructed stepwise from linear combinations of a small set of manually chosen internal coordinates, namely the predictors. The majority of the internal coordinates, the correctors, are optimized at every step of the SP to minimize the total energy of the system so that the path becomes a minimum energy path connecting products and transition states with the reactants. Problems arise when the set of predictors needs to include weak coordinates, for example, dihedral angles, as well as strong ones such as bond distances. Two principal constraining methods for the weak coordinates are proposed to mend this situation: static and dynamic constraints. Dynamic constraints are automatically activated and revoked depending on the state of the weak coordinates among the predictors, while static ones require preset control factors and act permanently. All these methods enable the successful application (4 reactions are presented involving cyclohexane, alanine dipeptide, trimethylsulfonium chloride, and azafulvene) of the reduced dimensionality method to reactions where the reaction path covers large conformational changes in addition to the formation/breaking of chemical bonds. Dynamic constraints are found to be the most efficient method as they require neither additional information about the geometry of the transition state nor fine tuning of control parameters.

  14. Chemical defense in Elodea nuttallii reduces feeding and growth of aquatic herbivorous Lepidoptera.

    PubMed

    Erhard, Daniela; Pohnert, Georg; Gross, Elisabeth M

    2007-08-01

    The submersed macrophyte Elodea nuttallii (Hydrocharitaceae) is invasive in Europe and frequently found in aquatic plant communities. Many invertebrate herbivores, such as larvae of the generalist aquatic moth, Acentria ephemerella (Lepidoptera, Pyralidae), avoid feeding on E. nuttallii and preferably consume native species. First instar larvae exhibited a high mortality on E. nuttallii compared to the native macrophyte Potamogeton perfoliatus. Mortality of older larvae was also high when fed E. nuttallii exposed to high light intensities. Growth of older larvae was strongly reduced on E. nuttallii compared to pondweeds (Potamogeton lucens). Neither differences in nitrogen nor phosphorus content explained the different performance on these submerged macrophytes, but plants differed in their flavonoid content. To investigate whether plant-derived allelochemicals from E. nuttallii affect larval performance in the same way as live plants, we developed a functional bioassay, in which Acentria larvae were reared on artificial diets. We offered larvae Potamogeton leaf disks coated with crude Elodea extracts and partially purified flavonoids. Elodea extracts deterred larvae from feeding on otherwise preferred Potamogeton leaves, and yet, unknown compounds in the extracts reduced growth and survival of Acentria. The flavonoid fraction containing luteolin-7-O-diglucuronide, apigenin-7-O-diglucuronide, and chrysoeriol-7-O-diglucuronide strongly reduced feeding of larvae, but did not increase mortality. The concentrations of these compounds in our assays were 0.01-0.09% of plant dry mass, which is in the lower range of concentrations found in the field (0.02-1.2%). Chemical defense in E. nuttallii thus plays an ecologically relevant role in this aquatic plant-herbivore system.

  15. Fitness costs of animal medication: antiparasitic plant chemicals reduce fitness of monarch butterfly hosts.

    PubMed

    Tao, Leiling; Hoang, Kevin M; Hunter, Mark D; de Roode, Jacobus C

    2016-09-01

    The emerging field of ecological immunology demonstrates that allocation by hosts to immune defence against parasites is constrained by the costs of those defences. However, the costs of non-immunological defences, which are important alternatives to canonical immune systems, are less well characterized. Estimating such costs is essential for our understanding of the ecology and evolution of alternative host defence strategies. Many animals have evolved medication behaviours, whereby they use antiparasitic compounds from their environment to protect themselves or their kin from parasitism. Documenting the costs of medication behaviours is complicated by natural variation in the medicinal components of diets and their covariance with other dietary components, such as macronutrients. In the current study, we explore the costs of the usage of antiparasitic compounds in monarch butterflies (Danaus plexippus), using natural variation in concentrations of antiparasitic compounds among plants. Upon infection by their specialist protozoan parasite Ophryocystis elektroscirrha, monarch butterflies can selectively oviposit on milkweed with high foliar concentrations of cardenolides, secondary chemicals that reduce parasite growth. Here, we show that these antiparasitic cardenolides can also impose significant costs on both uninfected and infected butterflies. Among eight milkweed species that vary substantially in their foliar cardenolide concentration and composition, we observed the opposing effects of cardenolides on monarch fitness traits. While high foliar cardenolide concentrations increased the tolerance of monarch butterflies to infection, they reduced the survival rate of caterpillars to adulthood. Additionally, although non-polar cardenolide compounds decreased the spore load of infected butterflies, they also reduced the life span of uninfected butterflies, resulting in a hump-shaped curve between cardenolide non-polarity and the life span of infected butterflies

  16. Dimensional reduction of the master equation for stochastic chemical networks: The reduced-multiplane method.

    PubMed

    Barzel, Baruch; Biham, Ofer; Kupferman, Raz; Lipshtat, Azi; Zait, Amir

    2010-08-01

    Chemical reaction networks which exhibit strong fluctuations are common in microscopic systems in which reactants appear in low copy numbers. The analysis of these networks requires stochastic methods, which come in two forms: direct integration of the master equation and Monte Carlo simulations. The master equation becomes infeasible for large networks because the number of equations increases exponentially with the number of reactive species. Monte Carlo methods, which are more efficient in integrating over the exponentially large phase space, also become impractical due to the large amounts of noisy data that need to be stored and analyzed. The recently introduced multiplane method [A. Lipshtat and O. Biham, Phys. Rev. Lett. 93, 170601 (2004)] is an efficient framework for the stochastic analysis of large reaction networks. It is a dimensional reduction method, based on the master equation, which provides a dramatic reduction in the number of equations without compromising the accuracy of the results. The reduction is achieved by breaking the network into a set of maximal fully connected subnetworks (maximal cliques). A separate master equation is written for the reduced probability distribution associated with each clique, with suitable coupling terms between them. This method is highly efficient in the case of sparse networks, in which the maximal cliques tend to be small. However, in dense networks some of the cliques may be rather large and the dimensional reduction is not as effective. Furthermore, the derivation of the multiplane equations from the master equation is tedious and difficult. Here we present the reduced-multiplane method in which the maximal cliques are broken down to the fundamental two-vertex cliques. The number of equations is further reduced, making the method highly efficient even for dense networks. Moreover, the equations take a simpler form, which can be easily constructed using a diagrammatic procedure, for any desired network

  17. Potential for reduction of burden and local elimination of malaria by reducing Plasmodium falciparum malaria transmission: a mathematical modelling study.

    PubMed

    Griffin, Jamie T; Bhatt, Samir; Sinka, Marianne E; Gething, Peter W; Lynch, Michael; Patouillard, Edith; Shutes, Erin; Newman, Robert D; Alonso, Pedro; Cibulskis, Richard E; Ghani, Azra C

    2016-04-01

    Rapid declines in malaria prevalence, cases, and deaths have been achieved globally during the past 15 years because of improved access to first-line treatment and vector control. We aimed to assess the intervention coverage needed to achieve further gains over the next 15 years. We used a mathematical model of the transmission of Plasmodium falciparum malaria to explore the potential effect on case incidence and malaria mortality rates from 2015 to 2030 of five different intervention scenarios: remaining at the intervention coverage levels of 2011-13 (Sustain), for which coverage comprises vector control and access to treatment; two scenarios of increased coverage to 80% (Accelerate 1) and 90% (Accelerate 2), with a switch from quinine to injectable artesunate for management of severe disease and seasonal malaria chemoprevention where recommended for both Accelerate scenarios, and rectal artesunate for pre-referral treatment at the community level added to Accelerate 2; a near-term innovation scenario (Innovate), which included longer-lasting insecticidal nets and expansion of seasonal malaria chemoprevention; and a reduction in coverage to 2006-08 levels (Reverse). We did the model simulations at the first administrative level (ie, state or province) for the 80 countries with sustained stable malaria transmission in 2010, accounting for variations in baseline endemicity, seasonality in transmission, vector species, and existing intervention coverage. To calculate the cases and deaths averted, we compared the total number of each under the five scenarios between 2015 and 2030 with the predicted number in 2015, accounting for population growth. With an increase to 80% coverage, we predicted a reduction in case incidence of 21% (95% credible intervals [CrI] 19-29) and a reduction in mortality rates of 40% (27-61) by 2030 compared with 2015 levels. Acceleration to 90% coverage and expansion of treatment at the community level was predicted to reduce case incidence by

  18. Soil structure, colloids, and chemical transport as affected by short-term reducing conditions: a laboratory study

    USDA-ARS?s Scientific Manuscript database

    Upland soils in the Midwestern US often undergo reducing conditions when soils are temporally flooded during the spring and remain water saturated for days or weeks. Short-term reducing conditions change the chemistry of the soil and may affect soil structure and solution chemical transport. The eff...

  19. Reduced chemical and electrical connections of fast-spiking interneurons in experimental cortical dysplasia.

    PubMed

    Zhou, Fu-Wen; Roper, Steven N

    2014-09-15

    Aberrant neural connections are regarded as a principal factor contributing to epileptogenesis. This study examined chemical and electrical connections between fast-spiking (FS), parvalbumin (PV)-immunoreactive (FS-PV) interneurons and regular-spiking (RS) neurons (pyramidal neurons or spiny stellate neurons) in a rat model of prenatal irradiation-induced cortical dysplasia. Presynaptic action potentials were evoked by current injection and the elicited unitary inhibitory or excitatory postsynaptic potentials (uIPSPs or uEPSPs) were recorded in the postsynaptic cell. In dysplastic cortex, connection rates between presynaptic FS-PV interneurons and postsynaptic RS neurons and FS-PV interneurons, and uIPSP amplitudes were significantly smaller than controls, but both failure rates and coefficient of variation of uIPSP amplitudes were larger than controls. In contrast, connection rates from RS neurons to FS-PV interneurons and uEPSPs amplitude were similar in the two groups. Assessment of the paired pulse ratio showed a significant decrease in synaptic release probability at FS-PV interneuronal terminals, and the density of terminal boutons on axons of biocytin-filled FS-PV interneurons was also decreased, suggesting presynaptic dysfunction in chemical synapses formed by FS-PV interneurons. Electrical connections were observed between FS-PV interneurons, and the connection rates and coupling coefficients were smaller in dysplastic cortex than controls. In dysplastic cortex, we found a reduced synaptic efficiency for uIPSPs originating from FS-PV interneurons regardless of the type of target cell, and impaired electrical connections between FS-PV interneurons. This expands our understanding of the fundamental impairment of inhibition in this model and may have relevance for certain types of human cortical dysplasia.

  20. The use of chemical restraints reduces agitation in patients transported by emergency medical services.

    PubMed

    Weiss, Steve; Peterson, Kari; Cheney, Paul; Froman, Phil; Ernst, Amy; Campbell, Micha

    2012-11-01

    Agitated patients are the primary source of injury to patients and providers during ambulance transport. Our primary hypothesis was that the addition of a chemical restraint agent (midazolam) to a restraint protocol would reduce agitation to a greater extent than a restraint protocol with physical restraint alone. The local emergency medical services restraint protocol (RP) was implemented on October 1, 2006. It included a form for data collection about each restrained patient. On April 1, 2007, chemical restraint (CR) using midazolam in addition to physical restraints was made available through the RP, and paramedics were educated in its use. Transported patients were divided into pre-CR and post-CR. The post-CR group was split into those who received and those who did not receive midazolam. Agitation was measured on a validated agitation behavior scale with a parametric (Rasch) adjustment. There were 96 patients in the pre-CR group and 522 patients in the post-CR group. Forty-three percent of the pre-CR group and 49% of the post-CR group had a decrease in agitation during transport (NS). Of the 522 in the post-CR group, 110 were physically restrained and given midazolam (21%) and 412 were physically restrained without midazolam (79%). There was a significantly greater decrease in agitation scores (-17 ± 21 vs. -7 ± 17) in the subjects receiving midazolam compared to those who did not. If available, CR is used in about 20% of restrained patients. When CR is used, there is a decrease in the subject's agitation. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Evaluation of reduced protocols for carcinogenicity testing of chemicals: report of a joint EPA/NIEHS workshop.

    PubMed

    Lai, D Y; Baetcke, K P; Vu, V T; Cotruvo, J A; Eustis, S L

    1994-04-01

    The current U.S. Environmental Protection Agency (EPA) and other national/international guidelines specify the use of two species and two sexes rodents (usually the rat and the mouse) for carcinogenicity testing of chemicals. In view of the enormous number of chemicals to be tested, the high cost of testing, and the large number of animals used in the present protocol, many academic, industrial, and government authorities are examining the possibility of using a reduced protocol (less than two species and two sexes of rodents) for carcinogenicity testing of chemicals. The use of a reduced protocol offers many advantages as well as some disadvantages. To pursue further the potential implications and impacts of using a reduced protocol for carcinogenicity testing on the processes of hazard identification and risk assessment, a workshop entitled "Evaluation of Reduced Protocols for Carcinogenicity Testing of Chemicals" was held at the Embassy Suites Hotel in Alexandria, Virginia on September 22 and 23, 1992. It was cosponsored by EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS) and the National Toxicology Program of the National Institutes of Environmental Health Sciences (NTP/NIEHS) and attended by more than 60 participants from government, industry, academia, and the general public. The Expert Consensus Panel and most of the participants supported the use of reduced protocols in carcinogenicity testing. However, it was recognized that reduced protocols may not be appropriate for the testing of all chemicals and that additional analyses/data may be needed for selection of the most appropriate reduced protocol for certain chemicals/chemical classes.

  2. Applying the three R's: Reduce, reuse, and recycle in the chemical industry.

    PubMed

    Mostafa, Mohamed K; Peters, Robert W

    2017-03-01

    Pollution prevention (P2) assessment was conducted by applying the three R's, reduce, reuse, and recycle, in a chemical industry for the purpose of reducing the amount of wastewater generated, reusing paint wastewater in the manufacture of cement bricks, recycling cooling water, and improving water usage efficiency. The results of this study showed that the annual wastewater flow generated from the paint manufacturing can be reduced from 1,100 m(3) to 488.4 m(3) (44.4% reduction) when a high-pressure hose is used. Two mixtures were prepared. The first mixture (A) contains cement, coarse aggregate, fine aggregate, Addicrete BVF, and clean water. The second mixture (B) contains the same components used in the first mixture, except that paint wastewater was used instead of the clean water. The prepared samples were tested for water absorption, toxicity, reactivity, compressive strength, ignitability, and corrosion. The tests results indicated that using paint wastewater in the manufacture of the cement bricks improved the mechanical properties of the bricks. The toxicity test results showed that the metals concentration in the bricks did not exceed the U.S. EPA limits. This company achieved the goal of zero liquid discharge (ZLD), especially after recycling 2,800 m(3) of cooling water. The total annual saving could reach $42,570 with a payback period of 41 days. This research focused on improving the water usage efficiency, reducing the quantity of wastewater generated, and potentially reusing wastewater in the manufacture of cement bricks. Reusing paint wastewater in the manufacture of the bricks prevents the hazardous pollutants in the wastewater (calcium carbonate, styrene acrylic resins, colored pigments, and titanium dioxide) from entering and polluting the surface water and the environment. We think that this paper will help to find the most efficient and cost-effective way to manage paint wastewater and conserve fresh water resources. We also believe that this

  3. A Probablistic Diagram to Guide Chemical Design with Reduced Potency to Incur Cytotoxicity

    EPA Science Inventory

    Toxicity is a concern with many chemicals currently in commerce, and with new chemicals that are introduced each year. The standard approach to testing chemicals is to run studies in laboratory animals (e.g. rats, mice, dogs), but because of the expense of these studies and conce...

  4. A Probablistic Diagram to Guide Chemical Design with Reduced Potency to Incur Cytotoxicity

    EPA Science Inventory

    Toxicity is a concern with many chemicals currently in commerce, and with new chemicals that are introduced each year. The standard approach to testing chemicals is to run studies in laboratory animals (e.g. rats, mice, dogs), but because of the expense of these studies and conce...

  5. Reducing drinking water supply chemical contamination: risks from underground storage tanks.

    PubMed

    Enander, Richard T; Hanumara, R Choudary; Kobayashi, Hisanori; Gagnon, Ronald N; Park, Eugene; Vallot, Christopher; Genovesi, Richard

    2012-12-01

    Drinking water supplies are at risk of contamination from a variety of physical, chemical, and biological sources. Ranked among these threats are hazardous material releases from leaking or improperly managed underground storage tanks located at municipal, commercial, and industrial facilities. To reduce human health and environmental risks associated with the subsurface storage of hazardous materials, government agencies have taken a variety of legislative and regulatory actions--which date back more than 25 years and include the establishment of rigorous equipment/technology/operational requirements and facility-by-facility inspection and enforcement programs. Given a history of more than 470,000 underground storage tank releases nationwide, the U.S. Environmental Protection Agency continues to report that 7,300 new leaks were found in federal fiscal year 2008, while nearly 103,000 old leaks remain to be cleaned up. In this article, we report on an alternate evidence-based intervention approach for reducing potential releases from the storage of petroleum products (gasoline, diesel, kerosene, heating/fuel oil, and waste oil) in underground tanks at commercial facilities located in Rhode Island. The objective of this study was to evaluate whether a new regulatory model can be used as a cost-effective alternative to traditional facility-by-facility inspection and enforcement programs for underground storage tanks. We conclude that the alternative model, using an emphasis on technical assistance tools, can produce measurable improvements in compliance performance, is a cost-effective adjunct to traditional facility-by-facility inspection and enforcement programs, and has the potential to allow regulatory agencies to decrease their frequency of inspections among low risk facilities without sacrificing compliance performance or increasing public health risks.

  6. Impact of temporal upscaling and chemical transport model horizontal resolution on reducing ozone exposure misclassification

    NASA Astrophysics Data System (ADS)

    Xu, Yadong; Serre, Marc L.; Reyes, Jeanette M.; Vizuete, William

    2017-10-01

    We have developed a Bayesian Maximum Entropy (BME) framework that integrates observations from a surface monitoring network and predictions from a Chemical Transport Model (CTM) to create improved exposure estimates that can be resolved into any spatial and temporal resolution. The flexibility of the framework allows for input of data in any choice of time scales and CTM predictions of any spatial resolution with varying associated degrees of estimation error and cost in terms of implementation and computation. This study quantifies the impact on exposure estimation error due to these choices by first comparing estimations errors when BME relied on ozone concentration data either as an hourly average, the daily maximum 8-h average (DM8A), or the daily 24-h average (D24A). Our analysis found that the use of DM8A and D24A data, although less computationally intensive, reduced estimation error more when compared to the use of hourly data. This was primarily due to the poorer CTM model performance in the hourly average predicted ozone. Our second analysis compared spatial variability and estimation errors when BME relied on CTM predictions with a grid cell resolution of 12 × 12 km2 versus a coarser resolution of 36 × 36 km2. Our analysis found that integrating the finer grid resolution CTM predictions not only reduced estimation error, but also increased the spatial variability in daily ozone estimates by 5 times. This improvement was due to the improved spatial gradients and model performance found in the finer resolved CTM simulation. The integration of observational and model predictions that is permitted in a BME framework continues to be a powerful approach for improving exposure estimates of ambient air pollution. The results of this analysis demonstrate the importance of also understanding model performance variability and its implications on exposure error.

  7. A dynamic multi-timescale method for combustion modeling with detailed and reduced chemical kinetic mechanisms

    SciTech Connect

    Gou, Xiaolong; Sun, Wenting; Ju, Yiguang; Chen, Zheng

    2010-06-15

    A new on-grid dynamic multi-timescale (MTS) method is presented to increase significantly the computation efficiency involving multi-physical and chemical processes using detailed and reduced kinetic mechanisms. The methodology of the MTS method using the instantaneous timescales of different species is introduced. The definition of the characteristic time for species is examined and compared with that of the computational singular perturbation (CSP) and frozen reaction rate methods by using a simple reaction system. A hybrid multi-timescale (HMTS) algorithm is constructed by integrating the MTS method with an implicit Euler scheme, respectively, for species with and without the requirement of accurate time histories at sub-base timescales. The efficiency and the robustness of the MTS and HMTS methods are demonstrated by comparing with the Euler and VODE solvers for homogenous ignition and unsteady flame propagation of hydrogen, methane, and n-decane-air mixtures. The results show that both MTS and HMTS reproduce well the species and temperature histories and are able to decrease computation time by about one-order with the same kinetic mechanism. Compared to MTS, HMTS has slightly better computation efficiency but scarifies the stability at large base time steps. The results also show that with the increase of mechanism size and the decrease of time step, the computation efficiency of multi-timescale method increases compared to the VODE solver. In addition, it is shown that the integration of the multi-timescale method with the path flux analysis based mechanism reduction approach can further increase the computation efficiency. Unsteady simulations of outwardly propagating spherical n-decane-air premixed flames demonstrate that the multi-timescale method is rigorous for direct numerical simulations with both detailed and reduced chemistry and can dramatically improve the computation efficiency. (author)

  8. Application of Chemically Accelerated Biotreatment to Reduce Risk in Oil-Impacted Soils

    SciTech Connect

    Paterek, J.R.; Bogan, W.W.; Sirivedhin; Tanita

    2003-03-06

    Research was conducted in six major focus areas: (1) Evaluation of the process using 6 test soils with full chemical and physical characteristics to determine controlling factors for biodegradation and chemical oxidation; (2) Determination of the sequestration time on chemical treatment suspectability; (3) Risk factors, i.e. toxicity after chemical and biological treatment; (4) Impact of chemical treatment (Fenton's Reagent) on the agents of biodegradation; (5) Description of a new genus and its type species that degrades hydrocarbons; and (6) Intermediates generate from Fenton's reagent treatment of various polynuclear aromatic hydrocarbons.

  9. Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments

    USGS Publications Warehouse

    Stoliker, Deborah L.; Campbell, Kate M.; Fox, Patricia M.; Singer, David M.; Kaviani, Nazila; Carey, Minna; Peck, Nicole E.; Barger, John R.; Kent, Douglas B.; Davis, James A.

    2013-01-01

    Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).

  10. Manipulating respiratory levels in Escherichia coli for aerobic formation of reduced chemical products.

    PubMed

    Zhu, Jiangfeng; Sánchez, Ailen; Bennett, George N; San, Ka-Yiu

    2011-11-01

    Optimizing the productivity of bioengineered strains requires balancing ATP generation and carbon atom conservation through fine-tuning cell respiration and metabolism. Traditional approaches manipulate cell respiration by altering air feeding, which are technically difficult especially in large bioreactors. An approach based on genetic regulation may better serve this purpose. With excess oxygen supply to the culture, we efficiently manipulated Escherichia coli cell respiration by adding different amount of coenzyme Q1 to strains lacking the ubiCA genes, which encode two critical enzymes for ubiquinone synthesis. As a proof-of-concept, the metabolic effect of the ubiCA gene knockout and coenzyme Q1 supplementation were characterized, and the metabolic profiles of the experimental strains showed clear correlations with coenzyme Q1 concentrations. Further proof-of-principle experiments were performed to illustrate that the approach can be used to optimize cell respiration for the production of chemicals of interest such as ethanol. This study showed that controlled respiration through genetic manipulation can be exploited to allow much larger operating windows for reduced product formation even under fully aerobic conditions.

  11. Chemical Reactivity Probes for Assessing Abiotic Natural Attenuation by Reducing Iron Minerals.

    PubMed

    Fan, Dimin; Bradley, Miranda J; Hinkle, Adrian W; Johnson, Richard L; Tratnyek, Paul G

    2016-02-16

    Increasing recognition that abiotic natural attenuation (NA) of chlorinated solvents can be important has created demand for improved methods to characterize the redox properties of the aquifer materials that are responsible for abiotic NA. This study explores one promising approach: using chemical reactivity probes (CRPs) to characterize the thermodynamic and kinetic aspects of contaminant reduction by reducing iron minerals. Assays of thermodynamic CRPs were developed to determine the reduction potentials (ECRP) of suspended minerals by spectrophotometric determination of equilibrium CRP speciation and calculations using the Nernst equation. ECRP varied as expected with mineral type, mineral loading, and Fe(II) concentration. Comparison of ECRP with reduction potentials measured potentiometrically using a Pt electrode (EPt) showed that ECRP was 100-150 mV more negative than EPt. When EPt was measured with small additions of CRPs, the systematic difference between EPt and ECRP was eliminated, suggesting that these CRPs are effective mediators of electron transfer between mineral and electrode surfaces. Model contaminants (4-chloronitrobenzene, 2-chloroacetophenone, and carbon tetrachloride) were used as kinetic CRPs. The reduction rate constants of kinetic CRPs correlated well with the ECRP for mineral suspensions. Using the rate constants compiled from literature for contaminants and relative mineral reduction potentials based on ECRP measurements, qualitatively consistent trends were obtained, suggesting that CRP-based assays may be useful for estimating abiotic NA rates of contaminants in groundwater.

  12. Reducing the emission of ozone depleting chemicals through use of a self-cleaning soldering process

    SciTech Connect

    Lichtenberg, L.; Martin, G.; Van Buren, P.; Iman, R.; Paffett, M.T.

    1991-12-31

    Motorola has jointed with Sandia and Los Alamos National Laboratories to perform work under a Cooperative Research and Development Agreement (CRADA) to reduce the use of CFC`s and other ozone depleting printing wiring board (PWB) cleaning solvents. This study evaluated the use of a new soldering process that uses dilute adipic acid in lieu of rosin flux. The process consumes the adipic acid in lieu of rosin flux. The process consumes the adipic acid during the soldering process and precludes the need for subsequent cleaning with ozone depleting solvents. This paper presents results from a series of designed experiments that evaluated PWB cleanliness as a function of various levels of machine control parameters. The study included a comprehensive hardware reliability evaluation, which included environmental conditioning, cleanliness testing, surface chemical analysis, surface insulation resistance testing, along with electrical, mechanical and long term storage testing. The results of this study that the new process produces quality, reliable hardware over a wide range of processing parameters. Adoption of this process, which eliminates the need for supplemental cleaning, will have a positive impact on many environmental problems, including depletion of the ozone layer.

  13. Reducing the emission of ozone depleting chemicals through use of a self-cleaning soldering process

    SciTech Connect

    Lichtenberg, L.; Martin, G.; Van Buren, P. . Government Electronics Group); Iman, R. ); Paffett, M.T. )

    1991-01-01

    Motorola has jointed with Sandia and Los Alamos National Laboratories to perform work under a Cooperative Research and Development Agreement (CRADA) to reduce the use of CFC's and other ozone depleting printing wiring board (PWB) cleaning solvents. This study evaluated the use of a new soldering process that uses dilute adipic acid in lieu of rosin flux. The process consumes the adipic acid in lieu of rosin flux. The process consumes the adipic acid during the soldering process and precludes the need for subsequent cleaning with ozone depleting solvents. This paper presents results from a series of designed experiments that evaluated PWB cleanliness as a function of various levels of machine control parameters. The study included a comprehensive hardware reliability evaluation, which included environmental conditioning, cleanliness testing, surface chemical analysis, surface insulation resistance testing, along with electrical, mechanical and long term storage testing. The results of this study that the new process produces quality, reliable hardware over a wide range of processing parameters. Adoption of this process, which eliminates the need for supplemental cleaning, will have a positive impact on many environmental problems, including depletion of the ozone layer.

  14. Excellent electromagnetic interference shielding effectiveness of chemically reduced graphitic oxide paper at 101 GHz*

    NASA Astrophysics Data System (ADS)

    Saini, Parveen; Kaushik, Sachin; Sharma, Rahul; Chakravarty, Disha; Raj, Rishi; Sharma, Jyotirmay

    2016-06-01

    Graphitic oxide (GO) was synthesized by oxidation of graphite powder using Hummer's method and the formed GO is solution processed into paper-like macroscopic form. Subsequently, chemically reduced graphitic oxide paper (CRGOP) is prepared by hydrazine vapours induced reduction of formed GO precursor based paper. The formation of GO and its successful reduction to RGO phase is confirmed by FTIR, Raman Spectroscopy and X-ray diffraction. It has been observed that due to high electrical conductivity ~200 micron thick CRGOP display excellent EMI shielding performance at very high frequency of 101 GHz frequency with total shielding effectiveness (SE) value of -35.49 dB (i.e. >99.97% blocking of incident EM radiation) which is much higher compared to pristine GO paper (-1.55 dB) or comparable to expanded graphite (EG) sheet (-35.61 dB). Due to their lightweight nature, these freestanding CRGOPs display average specific SE value of -221.8 dB cm3/g. Besides, their excellent flexibility and makes them potential candidate for lightweight EMI gasketing material compared to other forms of flexible carbons like EG.

  15. Dimensional reduction of the master equation for stochastic chemical networks: The reduced-multiplane method

    NASA Astrophysics Data System (ADS)

    Barzel, Baruch; Biham, Ofer; Kupferman, Raz; Lipshtat, Azi; Zait, Amir

    2010-08-01

    Chemical reaction networks which exhibit strong fluctuations are common in microscopic systems in which reactants appear in low copy numbers. The analysis of these networks requires stochastic methods, which come in two forms: direct integration of the master equation and Monte Carlo simulations. The master equation becomes infeasible for large networks because the number of equations increases exponentially with the number of reactive species. Monte Carlo methods, which are more efficient in integrating over the exponentially large phase space, also become impractical due to the large amounts of noisy data that need to be stored and analyzed. The recently introduced multiplane method [A. Lipshtat and O. Biham, Phys. Rev. Lett. 93, 170601 (2004)10.1103/PhysRevLett.93.170601] is an efficient framework for the stochastic analysis of large reaction networks. It is a dimensional reduction method, based on the master equation, which provides a dramatic reduction in the number of equations without compromising the accuracy of the results. The reduction is achieved by breaking the network into a set of maximal fully connected subnetworks (maximal cliques). A separate master equation is written for the reduced probability distribution associated with each clique, with suitable coupling terms between them. This method is highly efficient in the case of sparse networks, in which the maximal cliques tend to be small. However, in dense networks some of the cliques may be rather large and the dimensional reduction is not as effective. Furthermore, the derivation of the multiplane equations from the master equation is tedious and difficult. Here we present the reduced-multiplane method in which the maximal cliques are broken down to the fundamental two-vertex cliques. The number of equations is further reduced, making the method highly efficient even for dense networks. Moreover, the equations take a simpler form, which can be easily constructed using a diagrammatic procedure

  16. Soil structure, colloids, and chemical transport as affected by short-term reducing conditions: a laboratory study

    NASA Astrophysics Data System (ADS)

    de-Campos, A. B.; Mamedov, A. I.; Huang, C.; Wagner, L. E.

    2008-12-01

    Upland soils in the Midwestern US often undergo reducing conditions when soils are temporally flooded during the spring and remain water saturated for days or weeks. Short-term reducing conditions change the chemistry of the soil and may affect soil structure and solution chemical transport. The effects of short-term reducing conditions on chemical and physical properties of the soils, colloids, and associated chemical/nutrients transport are still not well understood and was the objective of our study. A biogeochemical reactor was built to achieve reducing conditions. Three cultivated and three uncultivated soils with different organic carbon contents were incubated in the reactor for 1 hour and 3 days under anaerobic conditions. Effects of the redox state on soil structure (pore size distribution) and drainable porosity, colloids mobility, and chemical transport were determined using high energy moisture characteristic and analytical methods. After each treatment, the soil solution was collected for redox potential (Eh), pH, and electrical conductivity (EC) measurements, and chemical analysis of metals (Ca, Mg, K), nutrients (N, P), and dissolved organic carbon. Strongly reducing conditions were achieved after 3 days of incubation and were followed by a decrease in soil porosity and an increase in pH, EC, clay dispersion, swelling, colloids mobility, and associated chemical transport. The trend for each soil depended on their initial structural stability and chemical properties. The structure of cultivated soils and the leaching of nutrients and carbon from uncultivated soils were more sensitive to the redox state. A strong correlation was found between changes in Eh and drainable porosity. The role of short-term reducing conditions on changes in redox sensitive elements, organic matter decomposition, pH, and EC and their influence on soil structure and soil particles or colloids/chemical transport for both soil groups are discussed in the paper. This study

  17. Method to reduce chemical background interference in atmospheric pressure ionization liquid chromatography-mass spectrometry using exclusive reactions with the chemical reagent dimethyl disulfide.

    PubMed

    Guo, Xinghua; Bruins, Andries P; Covey, Thomas R

    2007-06-01

    The interference of chemical background ions (chemical noise) has been a problem since the inception of mass spectrometry. We present here a novel method to reduce the chemical noise in LC-MS based on exclusive gas-phase reactions with a reactive collision gas in a triple-quadrupole mass spectrometer. Combined with the zero neutral loss (ZNL) scan of a triple-quadrupole mass spectrometer, the reactive chemical noise ions can be removed because of shifts of mass-to-charge ratios from the original background ions. The test on various classes of compounds with different functional groups indicates a generic application of this technique in LC-MS. The preliminary results show that a reduction of the level of LC-MS base-peak chromatographic baseline by a factor up to 40 and an improvement of the signal-to-noise ratio by a factor up to 5-10 are achieved on both commercial and custom-modified triple-quadrupole LC-MS systems. Application is foreseen in both quantitative and qualitative trace analysis. It is expected that this chemical noise reduction technique can be optimized on a dedicated mass spectrometric instrumentation which incorporates both a chemical reaction cell for noise reduction and a collision stage for fragmentation.

  18. Reduced trisialoganglioside synthesis in chemically but not mos-transformed mouse epidermal cells

    SciTech Connect

    Srinivas, L.; Colburn, N.H.

    1984-04-01

    A specific decrease in the net de novo synthesis ((1-14C)-glucosamine incorporation) of cell surface trisialoganglioside (GT) occurs in preneoplastic mouse JB6 epidermal cells in response to tumor-promoting phorbol esters, mezerein, or epidermal growth factor, all of which promote neoplastic transformation in JB6 cells, but not in response to the bladder promoter sodium cyclamate, a nonpromoter in JB6 cells. The ganglioside showing elevated synthesis after mezerein or epidermal growth factor exposure is monosialoganglioside 1, whereas disialoganglioside 1b synthesis is elevated after phorbol ester exposure. Primary mouse epidermal cells and putatively initiated epidermal cell lines selected for their resistance to induction of terminal differentiation by high calcium are resistant to promotion of anchorage-independent transformation by 2-week exposure to 12-O-tetradecanoylphorbol-13-acetate. In both cell types, little or no decrease in GT synthesis occurs in response to short-term 12-O-tetradecanoylphorbol-13-acetate exposure, thus extending further our previous observation that this GT response is restricted to promotable cells. A decreased synthesis of GT also occurs consistently in cell lines transformed by 12-O-tetradecanoylphorbol-13-acetate or N-methyl-N-nitro-nitrosoguanidine as compared with their nontransformed counterparts but not in cell lines transformed by a cloned integrated murine sarcoma provirus containing the oncogenic sequence v-mos. Thus, reduced cell surface GT synthesis may be important both in the induction and in the maintenance of the chemically transformed but not viral oncogene mos-transformed phenotype in mouse epidermal cells.

  19. Reducing the Risk of Dangerous Chemicals Getting into the Wrong Hands

    ERIC Educational Resources Information Center

    Matthews, Nancy

    2008-01-01

    Under the Department of Homeland Security (DHS) Appropriations Act of 2007, DHS has the authority and funding to regulate security at facilities storing chemicals considered to be high-risk (P. L. 109-295, Section 550). This article discusses the Department's efforts to enhance the security of facilities that store chemicals that could be stolen…

  20. Evaluation of effectiveness of chemical disinfectants in reducing bacterial growth on orthodontic instruments.

    PubMed

    Reddy, R Vamshidhar; Tanveer, K; Sharma, K Dinesh; Kokkula, Naveen; Suresh, P L; Sudhakar, Meher

    2013-11-01

    Infection control requires serious effort in all fields of dentistry including orthodontics. Though there are various means of sterilization and disinfection in dental office, chemical disinfection is the most preferred method among orthodontists. The purpose of this study is to evaluate different chemical sterilization and disinfection methods used in orthodontic offices, which would guide the orthodontists in infection control.

  1. Mathematical descriptors for the prediction of property, bioactivity, and toxicity of chemicals from their structure: a chemical-cum-biochemical approach.

    PubMed

    Basak, Subhash C

    2013-12-01

    This review article covers major aspects of mathematical chemistry, QSAR, chemoinformatics, bioinformatics, and molecular modeling research carried out by Subhash C. Basak and coworkers during 1968 to the present time in three distinct phases: 1) Department of Biochemistry, University of Calcutta and Charuchandra College, India (1968-1981); 2) Department of Chemistry & Biochemistry, University of Minnesota, Duluth, USA (1982-1987), and 3) Natural Resources Research Institute, University of Minnesota, Duluth, UMD-NRRI (1988-date). Topics discussed include development of novel mathematical descriptors of molecules and biomolecules; QSAR, HiQSAR, DiffQSAR and I-QSAR studies using chemodescriptors and biodescriptors; formulation of arbitrary quantitative molecular similarity analysis (QMSA) and tailored QMSA methods and their applications. The role of proper statistical methods in QSAR formulation and validation as well as the critical role of such methods in the molecular descriptor landscape of the twenty first century are also addressed.

  2. 76 FR 71310 - Notice of Intent To Reduce the Frequency of Chemical Use Surveys and All Associated Reports

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE National Agricultural Statistics Service Notice of Intent To Reduce the Frequency of Chemical Use Surveys and All Associated Reports AGENCY: National Agricultural Statistics Service, USDA. ACTION: Notice of...

  3. Columbia River Strategy for Measuring, Documenting and Reducing Chemicals of Emerging Concern - July 2014

    EPA Pesticide Factsheets

    Outline for a research and monitoring strategy for chemicals of emerging concern in the Columbia River Basin, and a characterization of the biological impacts of CECs on aquatic and terrestrial wildlife.

  4. SiGe growth kinetics and doping in reduced pressure-chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hartmann, J. M.; Loup, V.; Rolland, G.; Holliger, P.; Laugier, F.; Vannuffel, C.; Séméria, M. N.

    2002-03-01

    Using a reduced pressure-chemical vapor deposition cluster tool, we have studied the growth kinetics of Si and SiGe and the n-type and p-type doping of Si with both silane and dichlorosilane chemistries. As far as Si is concerned, a conventional behavior is found for both gases, i.e. a low-temperature region where the Si growth rate is limited by the desorption of the H atoms from the growing surface (activation energy equal to 47 kcal/mol), and a high-temperature region, where the Si growth rate is mainly piloted by the incoming flow of SiH 4 or SiH 2Cl 2 (activation energy of 4 kcal/mol). The incorporation of B in Si is linear with the B 2H 6 flow (p-type doping of Si), achievable with an overall 9×10 16-4×10 19 cm -3 B ions concentration range. There is a sub-linear dependency of the P incorporation into Si with the PH 3 flow (n-type doping of Si). A 2×10 16-9×10 18 cm -3 P ions concentration range can be reached with both silicon gas sources. The growth rate of boron-doped Si is virtually unaffected by increasing B 2H 6 flow. Meanwhile, the growth rate of phosphorous-doped Si steadily drops when the PH 3 flow is increased. As far as the SiH 4+GeH 4 chemistry is concerned, the Ge concentration x in the SiGe film obeys at 650°C the following law as a function of the F(GeH 4)/F(SiH 4) mass flow ratio: x/(1- x)=2.7(F(GeH 4)/F(SiH 4)). For the SiH 2Cl 2+GeH 4 chemistry, x is linked at 750°C to the F(GeH 4)/F(SiH 2Cl 2) mass flow ratio through the following relationship: x2/(1- x)=0.55(F(GeH 4)/F(SiH 2Cl 2)). The SiGe growth rate increases strongly with an increasing GeH 4 flow, with no apparent influence of the actual SiH 4 or SiH 2Cl 2 flow. This is attributed to an increased hydrogen desorption caused by the presence of Ge atoms on the growing surface that frees nucleation sites for the incoming Ge and Si atoms.

  5. Reducing the matrix effects in chemical analysis: fusion of isotope dilution and standard addition methods

    NASA Astrophysics Data System (ADS)

    Pagliano, Enea; Meija, Juris

    2016-04-01

    The combination of isotope dilution and mass spectrometry has become an ubiquitous tool of chemical analysis. Often perceived as one of the most accurate methods of chemical analysis, it is not without shortcomings. Current isotope dilution equations are not capable of fully addressing one of the key problems encountered in chemical analysis: the possible effect of sample matrix on measured isotope ratios. The method of standard addition does compensate for the effect of sample matrix by making sure that all measured solutions have identical composition. While it is impossible to attain such condition in traditional isotope dilution, we present equations which allow for matrix-matching between all measured solutions by fusion of isotope dilution and standard addition methods.

  6. APPLICATION OF CHEMICALLY ACCELERATED BIOTREATMENT TO REDUCE RISK IN OIL-IMPACTED SOILS

    SciTech Connect

    J.R. Paterek; W.W. Bogan; L.M. Lahner; A. May

    2000-04-01

    The overall program objective is to develop and evaluate integrated biological/physical/chemical co-treatment strategies for the remediation of wastes associated with the exploration and production of fossil energy. The specific objectives of this project are: chemical accelerated biotreatment (CAB) technology development for enhanced site remediation, application of the risk based analyses to define and support the rationale for environmental acceptable endpoints (EAE) for exploration and production wastes, and evaluate both the technological technologies in conjugation for effective remediation of hydrocarbon contaminated soils from E&P sites in the USA.

  7. APPLICATION OF CHEMICALLY ACCELERATED BIOTREATMENT TO REDUCE RISK IN OIL-IMPACTED SOILS

    SciTech Connect

    J.R. Paterek; W.W. Bogan; L.M. Lahner; V. Trbovic; E. Korach

    2001-05-01

    The overall program objective is to develop and evaluate integrated biological/physical/chemical co-treatment strategies for the remediation of wastes associated with the exploration and production of fossil energy. The specific objectives of this project are: chemical accelerated biotreatment (CAB) technology development for enhanced site remediation, application of the risk based analyses to define and support the rationale for environmental acceptable endpoints (EAE) for exploration and production wastes, and evaluate both the technological technologies in conjugation for effective remediation of hydrocarbon contaminated soils from E&P sites in the USA.

  8. Chemically Reduced Graphene Oxide for the Assessment of Food Quality: How the Electrochemical Platform Should Be Tailored to the Application.

    PubMed

    Chng, Chu'Er; Ambrosi, Adriano; Chua, Chun Kiang; Pumera, Martin; Bonanni, Alessandra

    2017-02-03

    Graphene platforms have been drawing considerable attention in electrochemistry for the detection of various electroactive probes. Depending on the chemical composition and properties of the probe, graphene materials with diverse structural features may be required to achieve an optimal electrochemical performance. This work comprises a comparative study on three chemically modified graphenes, obtained from the same starting material and with different oxygen functionalities and structural defects (graphene oxide (GO), chemically reduced graphene oxide (CRGO), and thermally reduced graphene oxide (TRGO)) towards the electrochemical detection of quinine, an important flavoring agent present in tonic-based beverages. In general, the reduced graphenes, namely CRGO and TRGO, showed enhanced performance in terms of calibration sensitivity and selectivity, due to the improved heterogeneous electron-transfer rates on their surfaces. In particular, CRGO provided the best overall electrochemical performance, which can be attributed to its higher density of structural defects and reduced amount of oxygen functionalities. For this reason, CRGO was employed for the electrochemical detection of quinine in commercial tonic drink samples, showing high sensitivity and selectivity, and therefore representing a valid low-cost alternative to more complicated and time consuming traditional analytical methods.

  9. Reducing Steam Pressure Saves $42,000 Annually at Vulcan Chemicals (VMC Geismar Plant)

    SciTech Connect

    2000-02-01

    As part of their Operational Excellence Program, Vulcan Chemicals, a business group of the Vulcan Materials Company, implemented a process optimization project involving two chloromethane production units. This four-month project required no capital investment and resulted in a reduction in process steam demand and significant cost savings.

  10. Innovative permeable cover system to reduce risks at a chemical munitions burial site

    SciTech Connect

    Powels, C.C.; Bon, I.; Okusu, N.M.

    1997-12-31

    An innovative permeable sand cover with various integrated systems has been designed to contain and treat the Old O-Field chemical munitions landfill at Aberdeen Proving Ground, Maryland. The 18,200 m{sup 2} (4.5 acre) landfill was used from the mid 1930s to the mid 1950s for the disposal of chemical, incendiary, and explosive munitions from domestic and foreign origins, together with contaminated wastes associated with the development and production of chemical warfare agents (CWA). The site is suspected to be contaminated with white phosphorous (WP) (which when dry, spontaneously burns when exposed to air), shock sensitive picric acid fuses and has the potential to contain large quantities of CWA-filled munitions. Historically, one to three explosions or fires occurred per ten-year period at the landfill. Such events have the potential to cause a CWA release to the environment, which could potentially affect densely populated areas. Recovery and decontamination projects conducted at the site in the late 1940s and early 1950s used large amounts of decontamination chemicals (containing solvents) and fuels which further contaminated the area. The groundwater downgradient of the landfill is contaminated with volatile organic compounds, metals, explosives and CWA degradation compounds and is currently being contained by a groundwater extraction and treatment system. This report describes a remedial action program for the site.

  11. Plant Growth-promoting Rhizobacteria Allow Reduced Application Rates of Chemical Fertilizers

    USDA-ARS?s Scientific Manuscript database

    Efforts to reduce fertilizer rates while increasing nutrient uptake to maintain high yields are very important due to the increasing cost of fertilizers and their potential negative environmental impacts. The objectives of this study were to determine (i) if reduced rates of inorganic fertilizer cou...

  12. The cost effectiveness of reducing public exposure to carcinogens in Harris County by a abating chemical plant emissions

    SciTech Connect

    Price, J.H. Jr.

    1989-01-01

    The work examines the engineering reasonableness and the cost effectiveness of reducing public exposure to carcinogens n ambient air by abating emissions of organic chemicals in waste gas streams from chemical plants in Harris County, Texas, which contains the large chemical manufacturing complex in the Houston ship channel areas. The work also examined the cost effectiveness of reducing public exposure through changing the way vent streams are released to the atmosphere. The achievable exposure reductions are estimated by use of 1980 census data and of ambient concentration estimates. The ambient concentration estimates are calculated using the Texas Climatological Model Version 2 (TCM-2) and publicly available emissions inventory collected by the Texas Air Control Board. The TCM-2 is based on the steady state Gaussian plume hypothesis, Briggs plume rise formations, Pasquill-Gifford dispersion coefficient approximations, and first order pollutant decay. The cost estimates rely on published studies and on the waste gas stream parameters of the chemical plant vents. The cost effectiveness results are compared with the cost effectiveness of controls typically applied to new sources of volatile organic compounds (VOCs) that are controlled because of their contribution to ozone air pollution, not because of the carcinogenicity of their emissions.

  13. Chemical modification of drug molecules as strategy to reduce interactions with mucus.

    PubMed

    Araújo, Francisca; Martins, Cláudia; Azevedo, Cláudia; Sarmento, Bruno

    2017-09-27

    Many drug molecules possess inadequate physical-chemical characteristics that prevent to surpass the viscous mucus layer present in the surface of mucosal tissues. Due to mucus protective role and its fast turnover, these drug molecules end up being removed from the body before being absorbed and, thus, before exerting any physiologic affect. Envisaging a better pharmacokinetics profile, chemical modifications, to render drug a more mucopenetrating character, have been introduced to drug molecules backbone towards more effective therapies. Mucus penetration increases when drug molecules are provided with net-neutral charge, when they are conjugated with mucolytic agents and through modifications that makes them resistant to enzymes present in mucus, with the overall increase of their hydrophilicity and the decrease of their molecular weight. All of these characteristics act as a whole and influence each other so they must be well thought when drug molecules are being designed for mucosal delivery. Copyright © 2017. Published by Elsevier B.V.

  14. Quantum chemical and solution phase evaluation of metallocenes as reducing agents for the prospective atomic layer deposition of copper.

    PubMed

    Dey, Gangotri; Wrench, Jacqueline S; Hagen, Dirk J; Keeney, Lynette; Elliott, Simon D

    2015-06-14

    We propose and evaluate the use of metallocene compounds as reducing agents for the chemical vapour deposition (and specifically atomic layer deposition, ALD) of the transition metal Cu from metalorganic precursors. Ten different transition metal cyclopentadienyl compounds are screened for their utility in the reduction of Cu from five different Cu precursors by evaluating model reaction energies with density functional theory (DFT) and solution phase chemistry.

  15. The relationship among mathematics anxiety, beliefs about mathematics, mathematics self-efficacy, and mathematics performance in associate degree nursing students.

    PubMed

    Walsh, Kathleen A

    2008-01-01

    This research explored nursing students' mathematics anxiety, beliefs about mathematics, and mathematics self-efficacy in relation to performance on a medication mathematics test. Results revealed that the participants experienced some mathematics anxiety and had positive beliefs about mathematics and mathematics self-efficacy. Qualitative responses indicated that participants worried about the consequences of failing the medication mathematics test and that practice helped reduce this anxiety. In addition, participants acknowledged the importance of correct dosage calculations for nursing practice. Implications for nursing education are discussed.

  16. Chemicals isolated from Justicia adhatoda Linn reduce fitness of the mosquito, Aedes aegypti L.

    PubMed

    Thanigaivel, Annamalai; Senthil-Nathan, Sengottayan; Vasantha-Srinivasan, Prabhakaran; Edwin, Edward-Sam; Ponsankar, Athirstam; Selin-Rani, Selvaraj; Pradeepa, Venkatraman; Chellappandian, Muthiah; Kalaivani, Kandaswamy; Abdel-Megeed, Ahmed; Narayanan, Raman; Murugan, Kadarkarai

    2017-04-01

    Extracts from Justicia adhatoda L. (Acanthaceae) strongly reduced the fitness of the mosquito, Aedes aegypti Linn. The methanolic extracts inhibited several enzymes responsible for protecting insects from oxidative and other damage, including glutathione-S-transferase, superoxide dismutase, cytochrome P450, and α- and β-esterases. They increased repellency (maximum repellency at 100 ppm) in host-seeking adult females using the "arm-in cage assay." Histopathological examination showed the extracts led to serious midgut cell damage. Justicia adhatoda extracts led to reduced fecundity and oviposition of gravid females compared to controls. The extracts led to substantially reduced A. aegypti survival. We infer that the extracts have potential to reduce pathogen transmission by suppressing population growth of A. aegypti, and possibly other mosquito species. © 2017 Wiley Periodicals, Inc.

  17. A mathematical model for mixed convective flow of chemically reactive Oldroyd-B fluid between isothermal stretching disks

    NASA Astrophysics Data System (ADS)

    Hashmi, M. S.; Khan, N.; Ullah Khan, Sami; Rashidi, M. M.

    In this study, we have constructed a mathematical model to investigate the heat source/sink effects in mixed convection axisymmetric flow of an incompressible, electrically conducting Oldroyd-B fluid between two infinite isothermal stretching disks. The effects of viscous dissipation and Joule heating are also considered in the heat equation. The governing partial differential equations are converted into ordinary differential equations by using appropriate similarity variables. The series solution of these dimensionless equations is constructed by using homotopy analysis method. The convergence of the obtained solution is carefully examined. The effects of various involved parameters on pressure, velocity and temperature profiles are comprehensively studied. A graphical analysis has been presented for various values of problem parameters. The numerical values of wall shear stress and Nusselt number are computed at both upper and lower disks. Moreover, a graphical and tabular explanation for critical values of Frank-Kamenetskii regarding other flow parameters.

  18. Application of Chemically Accelerated Biotreatment to Reduce Risk in Oil-Impacted Soils

    SciTech Connect

    Paterek, J.R.; Bogan, W.W.; Lahner, L.M.; Trbovic, V.

    2003-03-06

    Conducted research in the following major focus areas: (1) Development of mild extraction approaches to estimate bioavailable fraction of crude oil residues in contaminated soils; (2) Application of these methods to understand decreases in toxicity and increases in sequestration of hydrocarbons over time, as well as the influence of soil properties on these processes; (3) Measurements of the abilities of various bacteria (PAH-degraders and others more representative of typical soil bacteria) to withstand oxidative treatments (i.e. Fenton's reaction) which would occur in CBT; and (4) Experiments into the biochemical/genetic inducibility of PAH degradation by compounds formed by the chemical oxidation of PAH.

  19. A biological/chemical process for reduced waste and energy consumption: caprolactam production. Final report

    SciTech Connect

    1996-05-01

    A biological/chemical process for converting cyclohexane into caprolactam was investigated: microorganisms in a bioreactor would be used to convert cyclohexane into caprolactone followed by chemical synthesis of caprolactam using ammonia. Four microorganisms were isolated from natural soil and water, that can utilize cyclohexane as a sole source of C and energy for growth. They were shown to have the correct metabolic intermediates and enzymes to convert cyclohexane into cyclohexanol, cyclohexanone, and caprolactone. Genetic techniques to create and select for caprolactone hydrolase negative-mutants were developed; those are used to convert cyclohexane into caprolactone but, because of the block, are unable to metabolize the caprolactone further. Because of a new nylon carpet reycle process and the long time frame for a totally new bioprocess, a limited study was done to evaluate whether a simplified bioprocess to convert cyclohexanol into cyclohexanone or caprolactone was feasible; growth rates and key enzyme levels were measured in a collection of microorganisms that metabolize cyclohexanol to determine if the bioactivity is high enough to support an economical cyclohexanol bioprocess. Although these microorganisms had sufficient bioactivity, they could tolerate only low levels (<1%) of cyclohexanol and thus are not suitable for developing a cost effective bioprocess because of the high cost of dilute product recovery.

  20. Reduced weight decontamination formulation for neutralization of chemical and biological warfare agents

    SciTech Connect

    Tucker, Mark D.

    2014-06-03

    A reduced weight DF-200 decontamination formulation that is stable under high temperature storage conditions. The formulation can be pre-packed as an all-dry (i.e., no water) or nearly-dry (i.e., minimal water) three-part kit, with make-up water (the fourth part) being added later in the field at the point of use.

  1. Clean Air Act Settlement Reduces Air Emissions and Improves Chemical Safety at Rhode Island Biodiesel Plant

    EPA Pesticide Factsheets

    The U.S. EPA & U.S. Department of Justice have settled an environmental enforcement case with Newport Biodiesel, Inc., resulting in reduced air emissions and improved safety controls at the company’s biodiesel manufacturing plant in Newport, Rhode Island.

  2. A Chemical Treatment to Reduce P Desorption From Manure Exposed Fluvial Sediments

    USDA-ARS?s Scientific Manuscript database

    The current remediation methods for manure spills that have reached surface waters give no attention to the P enriched ditch sediments that remain in the fluvial system and continue to impair the water column. Consequently, no method exists to treat P contaminated sediments to reduce their ability ...

  3. Effects of reservoir anaerobic, reducing conditions on surfactant retention in chemical flooding

    SciTech Connect

    Wang, F.H.L. )

    1993-05-01

    Surfactant retentions observed in four microemulsion-flooding pilot tests at the Loudon field were substantially lower than predicted from conventional laboratory coreflood experiments. This paper presents research results that explain this discrepancy. The oil reservoir was in an anaerobic, reducing conditions, whereas laboratory corefloods were normally conducted under aerobic, oxidizing conditions. The difference in redox condition was shown to have a serious effect on surfactant retention. Laboratory corefloods conducted under reservoir-like, anaerobic, reducing conditions gave surfactant retention results significantly closer to those observed in field tests. The effect of redox conditions on surfactant adsorption was substantiated further by results from static adsorption experiments with various clay types. Exposure of preserved cores from a reduced reservoir to aerobic conditions can cause high surfactant retention in corefloods. Methods were developed to restore such oxygen-contaminated core material to its original, anaerobic, reduced state. These coreflood procedures simulate actual reservoir conditions better and give meaningful surfactant-retention results for process design optimization.

  4. Transformation impacts of dissolved and solid phase Fe(II) on trichloroethylene (TCE) reduction in an iron-reducing bacteria (IRB) mixed column system: a mathematical model.

    PubMed

    Bae, Yeunook; Kim, Dooil; Cho, Hyun-Hee; Singhal, Naresh; Park, Jae-Woo

    2012-12-01

    In this research, we conducted trichloroethylene (TCE) reduction in a column filled with iron and iron-reducing bacteria (IRB) and developed a mathematical model to investigate the critical reactions between active species in iron/IRB/contaminant systems. The formation of ferrous iron (Fe(II)) in this system with IRB and zero-valent iron (ZVI, Fe(0)) coated with a ferric iron (Fe(III)) crust significantly affected TCE reduction and IRB respiration in various ways. This study presents a new framework for transformation property and reducing ability of both dissolved (Fe(II)(dissolved)) and solid form ferrous iron (Fe(II)(solid)). Results showed that TCE reduction was strongly depressed by Fe(II)(solid) rather than by other inhibitors (e.g., Fe(III) and lactate), suggesting that Fe(II)(solid) might reduce IRB activation due to attachment to IRB cells. Newly exposed Fe(0) from the released Fe(II)(dissolved) was a strong contributor to TCE reduction compared to Fe(II)(solid). In addition, our research confirmed that less Fe(II)(solid) production strongly supported long-term TCE reduction because it may create an easier TCE approach to Fe(0) or increase IRB growth. Our findings will aid the understanding of the contributions of iron media (e.g., Fe(II)(solid), Fe(II)(dissolved), Fe(III), and Fe(0)) to IRB for decontamination in natural groundwater systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Selecting the optimum quasi-steady-state species for reduced chemical kinetic mechanisms using a genetic algorithm

    SciTech Connect

    Montgomery, Christopher J.; Yang, Chongguan; Parkinson, Alan R.; Chen, J.-Y.

    2006-01-01

    A genetic optimization algorithm has been applied to the selection of quasi-steady-state (QSS) species in reduced chemical kinetic mechanisms. The algorithm seeks to minimize the error between reduced and detailed chemistry for simple reactor calculations approximating conditions of interest for a computational fluid dynamics simulation. The genetic algorithm does not guarantee that the global optimum will be found, but much greater accuracy can be obtained than by choosing QSS species through a simple kinetic criterion or by human trial and error. The algorithm is demonstrated for methane-air combustion over a range of temperatures and stoichiometries and for homogeneous charge compression ignition engine combustion. The results are in excellent agreement with those predicted by the baseline mechanism. A factor of two reduction in the number of species was obtained for a skeletal mechanism that had already been greatly reduced from the parent detailed mechanism.

  6. Coupled Physical/Chemical and Biofiltration Technologies to Reduce Air Emissions from Forest Products Industries

    SciTech Connect

    Gary D. McGinnis

    2001-12-31

    The research is a laboratory and bench-scale investigation of a system to concentrate and destroy volatile organic compounds (VOCs), including hazardous air pollutants, formed from the drying of wood and the manufacture of wood board products (e.g., particle board and oriented strandboard). The approach that was investigated involved concentrating the dilute VOCs (<500 ppmv) with a physical/chemical adsorption unit, followed by the treatment of the concentrated voc stream (2,000 to 2,500 ppmv) with a biofiltration unit. The research program lasted three years, and involved three research organizations. Michigan Technological University was the primary recipient of the financial assistance, the USDA Forest Products Laboratory (FPL) and Mississippi State University (MSU) were subcontractors to MTU. The ultimate objective of this research was to develop a pilot-scale demonstration of the technology with sufficient data to provide for the design of an industrial system. No commercialization activities were included in this project.

  7. APPLICATION OF CHEMICALLY ACCELERATED BIOTREATMENT TO REDUCE RISKIN OIL-IMPACTED SOILS

    SciTech Connect

    J.R. Paterek; W.W.Bogan; V. Trbovic; W. Sullivan

    2003-01-07

    The drilling and operation of gas/petroleum exploratory wells and the operations of natural gas and petroleum production wells generate a number of waste materials that are usually stored and/or processed at the drilling/operations site. Contaminated soils result from drilling operations, production operations, and pipeline breaks or leaks where crude oil and petroleum products are released into the surrounding soil or sediments. In many cases, intrinsic biochemical remediation of these contaminated soils is either not effective or is too slow to be an acceptable approach. This project targeted petroleum-impacted soil and other wastes, such as soil contaminated by: accidental release of petroleum and natural gas-associated organic wastes from pipelines or during transport of crude oil or natural gas; production wastes (such as produced waters, and/or fuels or product gas). Our research evaluated the process designated Chemically-Accelerated Biotreatment (CAB) that can be applied to remediate contaminated matrices, either on-site or in situ. The Gas Technology Institute (GTI) had previously developed a form of CAB for the remediation of hydrocarbons and metals at Manufactured Gas Plant (MGP) sites and this research project expanded its application into Exploration and Production (E&P) sites. The CAB treatment was developed in this project using risk-based endpoints, a.k.a. environmentally acceptable endpoints (EAE) as the treatment goal. This goal was evaluated, compared, and correlated to traditional analytical methods (Gas Chromatography (GC), High Precision Liquid Chromatography (HPLC), or Gas Chromatography-Mass Spectrometry (CGMS)). This project proved that CAB can be applied to remediate E&P contaminated soils to EAE, i.e. those concentrations of chemical contaminants in soil below which there is no adverse affect to human health or the environment. Conventional approaches to risk assessment to determine ''how clean is clean'' for soils undergoing remediation

  8. Reducing flicker noise in chemical vapor deposition graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Arnold, Heather N.; Sangwan, Vinod K.; Schmucker, Scott W.; Cress, Cory D.; Luck, Kyle A.; Friedman, Adam L.; Robinson, Jeremy T.; Marks, Tobin J.; Hersam, Mark C.

    2016-02-01

    Single-layer graphene derived from chemical vapor deposition (CVD) holds promise for scalable radio frequency (RF) electronic applications. However, prevalent low-frequency flicker noise (1/f noise) in CVD graphene field-effect transistors is often up-converted to higher frequencies, thus limiting RF device performance. Here, we achieve an order of magnitude reduction in 1/f noise in field-effect transistors based on CVD graphene transferred onto silicon oxide substrates by utilizing a processing protocol that avoids aqueous chemistry after graphene transfer. Correspondingly, the normalized noise spectral density (10-7-10-8 μm2 Hz-1) and noise amplitude (4 × 10-8-10-7) in these devices are comparable to those of exfoliated and suspended graphene. We attribute the reduction in 1/f noise to a decrease in the contribution of fluctuations in the scattering cross-sections of carriers arising from dynamic redistribution of interfacial disorder.

  9. Cloning of Tetrahymena cells in a chemically defined medium is possible in the presence of surfactants or at reduced temperature.

    PubMed

    Hellung-Larsen, Per

    2005-01-26

    When Tetrahymena cells are exposed to physical or chemical stress they may die. The effect of a given stress depends on the culture medium, the temperature, and the manipulation of the cells. Cells in broth-medium or buffer solution are more resistant than cells in chemically defined medium (CDM). A type of physical stress is caused by the hydrodynamic properties at the constriction of the pipette tip. This type of stress may be reduced/abolished by use of tips with maximal area and smoothness at the constrictions, underwater delivery of cell suspensions combined with gentle mixing, by use of reduced temperatures, by avoidance of medium-air interfaces or by addition of surfactants. By adjustment of these parameters it is possible to clone single cells of different species of Tetrahymena in CDM. In the presence of surfactants, cells can be cloned even under harsh manipulation. In absence of surfactants, cells can be cloned at 15 degrees C using mild manipulations. Tetrahymena cells are independent of unspecific growth factors and they do not exert autocrine growth control. Pluronic does not bind to the cells with significant affinity. Chemical stress cannot be counteracted by surfactants. Pre-stress (heat) protects the cells from subsequent lethal heat stress.

  10. Synthesis of reduced graphene oxide (rGO) via chemical reduction

    SciTech Connect

    Thakur, Alpana Rangra, V. S.; Kumar, Sunil

    2015-05-15

    Natural flake Graphite was used as the starting material for the graphene synthesis. In the first step flake graphite was treated with oxidizing agents under vigorous conditions to obtain graphite oxide. Layered graphite oxide decorated with oxygen has large inter-layer distance leading easy exfoliation into single sheets by ultrasonication giving graphene oxide. In the last step exfoliated graphene oxide sheets were reduced slowly with the help of reducing agent to obtain fine powder which is labeled as reduced graphene oxide (rGO). This rGO was further characterized by X-Ray Diffraction (XRD), Scanning Tunneling Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy techniques. XRD pattern shows peaks corresponding to (002) graphitic lattice planes indicating the formation of network of sp{sup 2} like carbon structure. SEM images show the ultrathin, wrinkled, paper-like morphology of graphene sheets. IR study shows that the graphite has been oxidized to graphite oxide with the presence of various absorption bands confirming the presence of oxidizing groups. The FTIR spectrum of rGO shows no sharp peaks confirming the efficient reduction of rGO. The Raman spectrum shows disorder in the graphene sheets.

  11. Reducing Mortality from Terrorist Releases of Chemical and Biological Agents: I. Filtration for Ventilation Systems in Commercial Building

    SciTech Connect

    Thatcher, Tracy L.; Daisey, Joan M.

    1999-09-01

    There is growing concern about potential terrorist attacks involving releases of chemical and/or biological (CB) agents, such as sarin or anthrax, in and around buildings. For an external release, the CB agent can enter the building through the air intakes of a building's mechanical ventilation system and by infiltration through the building envelope. For an interior release in a single room, the mechanical ventilation system, which often recirculates some fraction of the air within a building, may distribute the released CB agent throughout the building. For both cases, installing building systems that remove chemical and biological agents may be the most effective way to protect building occupants. Filtration systems installed in the heating, ventilating and air-conditioning (HVAC) systems of buildings can significantly reduce exposures of building occupants in the event of a release, whether the release is outdoors or indoors. Reduced exposures can reduce the number of deaths from a terrorist attack. The purpose of this report is to provide information and examples of the design of filtration systems to help building engineers retrofit HVAC systems. The report also provides background information on the physical nature of CB agents and brief overviews of the basic principles of particle and vapor filtration.

  12. Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment

    SciTech Connect

    Pham, Chuyen V.; Krueger, Michael E-mail: emre.erdem@physchem.uni-freiburg.de; Eck, Michael; Weber, Stefan; Erdem, Emre E-mail: emre.erdem@physchem.uni-freiburg.de

    2014-03-31

    Electron paramagnetic resonance (EPR) spectroscopy has been applied to different chemically treated reduced graphene oxide (rGO) and multiwalled carbon nanotubes (CNTs). A narrow EPR signal is visible at g = 2.0029 in both GO and CNT-Oxide from carbon-related dangling bonds. EPR signals became broader and of lower intensity after oxygen-containing functionalities were reduced and partially transformed into thiol groups to obtain thiol-functionalized reduced GO (TrGO) and thiol-functionalized CNT (CNT-SH), respectively. Additionally, EPR investigation of CdSe quantum dot-TrGO hybrid material reveals complete quenching of the TrGO EPR signal due to direct chemical attachment and electronic coupling. Our work confirms that EPR is a suitable tool to detect spin density changes in different functionalized nanocarbon materials and can contribute to improved understanding of electronic coupling effects in nanocarbon-nanoparticle hybrid nano-composites promising for various electronic and optoelectronic applications.

  13. Correlations between Prenatal Exposure to Perfluorinated Chemicals and Reduced Fetal Growth

    PubMed Central

    Washino, Noriaki; Saijo, Yasuaki; Sasaki, Seiko; Kato, Shizue; Ban, Susumu; Konishi, Kanae; Ito, Rie; Nakata, Ayako; Iwasaki, Yusuke; Saito, Koichi; Nakazawa, Hiroyuki; Kishi, Reiko

    2009-01-01

    Background Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are man-made, ubiquitous, and persistent contaminants in the environment, wildlife, and humans. Although recent studies have shown that these chemicals interfere with fetal growth in humans, the results are inconsistent. Objectives Our goal was to investigate the correlation between relatively low levels of PFOS and PFOA in maternal serum and birth weight and birth size. Methods We conducted a hospital-based prospective cohort study between July 2002 and October 2005 in Sapporo, Japan. A total of 428 women and their infants were involved in the study. We obtained characteristics of the mothers and infants from self-administered questionnaire surveys and from medical records. We analyzed maternal serum samples for PFOS and PFOA by liquid chromatography–tandem mass spectrometry (LC/MS/MS). Results After adjusting for confounding factors, PFOS levels negatively correlated with birth weight [per log10 unit: β = −148.8 g; 95% confidence interval (CI), −297.0 to −0.5 g]. In addition, analyses stratified by sex revealed that PFOS levels negatively correlated with birth weight only in female infants (per log10 unit: β = −269.4 g; 95% CI, −465.7 to −73.0 g). However, we observed no correlation between PFOA levels and birth weight. Conclusion Our results indicate that in utero exposure to relatively low levels of PFOS was negatively correlated with birth weight. PMID:19440508

  14. A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors

    PubMed Central

    Comini, Elisabetta; Kholmanov, Iskandar; Ponzoni, Andrea; Sberveglieri, Veronica; Poli, Nicola; Faglia, Guido; Sberveglieri, Giorgio

    2016-01-01

    Summary A hybrid nanostructure based on reduced graphene oxide and ZnO has been obtained for the detection of volatile organic compounds. The sensing properties of the hybrid structure have been studied for different concentrations of ethanol and acetone. The response of the hybrid material is significantly higher compared to pristine ZnO nanostructures. The obtained results have shown that the nanohybrid is a promising structure for the monitoring of environmental pollutants and for the application of breath tests in assessment of exposure to volatile organic compounds. PMID:27826516

  15. Mathematical equations and system identification models for a portable pneumatic bladder system designed to reduce human exposure to whole body shock and vibration

    NASA Astrophysics Data System (ADS)

    Aziz Ayyad, Ezzat

    A mathematical representation is sought to model the behavior of a portable pneumatic foam bladder designed to mitigate the effects of human exposure to shock and whole body random vibration. Fluid Dynamics principles are used to derive the analytic differential equations used for the physical equations Model. Additionally, combination of Wiener and Hammerstein block oriented representation techniques have been selected to create system identification (SID) block oriented models. A number of algorithms have been iterated to obtain numerical solutions for the system of equations which was found to be coupled and non-linear, with no analytic closed form solution. The purpose is to be able to predict the response of such system due to random vibrations and shock within reasonable margin of error. The constructed models were found to be accurate within accepted confidence level. Beside the analytic set of physical equations model representation, a linear SID model was selected to take advantage of the available vast amount of mathematical tools available to further analyze and redesign the bladder as a dynamic system. Measured field-test and lab test data have been collected from several helicopter and land terrain vehicle experiments. Numerous excitation and response acceleration measurement records were collected and used to prove the agreement with predictions. The estimation of two selected models were later applied to standard metrics in the frequency domain realization and compared with measurement responses. The collected test records are obtained from measured data at the US Army fields and facilities and at UNLV-CMEST environmental lab. The emerged models have been validated for conformity with actual accelerometer measurement responses and found within accepted error tolerance that is in both time and frequency domains. Further, standard metrics have been used to further confirm the confidence in the validation results. When comparing model prediction with

  16. Chemical property based sequence characterization of PpcA and its homolog proteins PpcB-E: A mathematical approach

    PubMed Central

    Pal Choudhury, Pabitra

    2017-01-01

    Periplasmic c7 type cytochrome A (PpcA) protein is determined in Geobacter sulfurreducens along with its other four homologs (PpcB-E). From the crystal structure viewpoint the observation emerges that PpcA protein can bind with Deoxycholate (DXCA), while its other homologs do not. But it is yet to be established with certainty the reason behind this from primary protein sequence information. This study is primarily based on primary protein sequence analysis through the chemical basis of embedded amino acids. Firstly, we look for the chemical group specific score of amino acids. Along with this, we have developed a new methodology for the phylogenetic analysis based on chemical group dissimilarities of amino acids. This new methodology is applied to the cytochrome c7 family members and pinpoint how a particular sequence is differing with others. Secondly, we build a graph theoretic model on using amino acid sequences which is also applied to the cytochrome c7 family members and some unique characteristics and their domains are highlighted. Thirdly, we search for unique patterns as subsequences which are common among the group or specific individual member. In all the cases, we are able to show some distinct features of PpcA that emerges PpcA as an outstanding protein compared to its other homologs, resulting towards its binding with deoxycholate. Similarly, some notable features for the structurally dissimilar protein PpcD compared to the other homologs are also brought out. Further, the five members of cytochrome family being homolog proteins, they must have some common significant features which are also enumerated in this study. PMID:28362850

  17. Chemical property based sequence characterization of PpcA and its homolog proteins PpcB-E: A mathematical approach.

    PubMed

    Das, Jayanta Kumar; Pal Choudhury, Pabitra

    2017-01-01

    Periplasmic c7 type cytochrome A (PpcA) protein is determined in Geobacter sulfurreducens along with its other four homologs (PpcB-E). From the crystal structure viewpoint the observation emerges that PpcA protein can bind with Deoxycholate (DXCA), while its other homologs do not. But it is yet to be established with certainty the reason behind this from primary protein sequence information. This study is primarily based on primary protein sequence analysis through the chemical basis of embedded amino acids. Firstly, we look for the chemical group specific score of amino acids. Along with this, we have developed a new methodology for the phylogenetic analysis based on chemical group dissimilarities of amino acids. This new methodology is applied to the cytochrome c7 family members and pinpoint how a particular sequence is differing with others. Secondly, we build a graph theoretic model on using amino acid sequences which is also applied to the cytochrome c7 family members and some unique characteristics and their domains are highlighted. Thirdly, we search for unique patterns as subsequences which are common among the group or specific individual member. In all the cases, we are able to show some distinct features of PpcA that emerges PpcA as an outstanding protein compared to its other homologs, resulting towards its binding with deoxycholate. Similarly, some notable features for the structurally dissimilar protein PpcD compared to the other homologs are also brought out. Further, the five members of cytochrome family being homolog proteins, they must have some common significant features which are also enumerated in this study.

  18. Superior performance of asymmetric supercapacitor based on reduced graphene oxide-manganese carbonate as positive and sono-chemically reduced graphene oxide as negative electrode materials

    NASA Astrophysics Data System (ADS)

    Jana, Milan; Kumar, J. Sharath; Khanra, Partha; Samanta, Pranab; Koo, Hyeyoung; Murmu, Naresh Chandra; Kuila, Tapas

    2016-01-01

    A novel strategy to synthesize hierarchical rod like MnCO3 on the reduced graphene oxide (RGO) sheets by a facile and cost-effective hydrothermal method is demonstrated. The chelating action of citric acid facilitates the formation a complex intermediate of Mn2+ and citrate ions, which finally results a 3D MnCO3/RGO (MRGO) composite with high electrical conductivity (∼1056 S m-1), good surface area (59 m2 g-1) and high pore volume (0.3 cm3 g-1). The specific capacitance (SC) of the MRGO composite is ∼1120 F g-1 at a current density of 2 A g-1 in three electrode system. An asymmetric device has been designed with MRGO as positive and sono-chemically reduced RGO (SRGO) as negative electrode material. The asymmetric device (MRGO//SRGO) shows the SC of ∼318 F g-1 (at 2 A g-1) and energy density of ∼113 W h kg-1 (at 1600 W kg-1). The true energy density (1.7 W h kg-1) has been calculated considering the total weight of the device. The MRGO//SRGO device can power a wall clock for ∼13 min after full charging. The Nyquist plot of the asymmetric cell has been simulated with Z-View software to measure the solution resistance, charge-transfer resistance and Warburg elements.

  19. Plant growth-promoting rhizobacteria allow reduced application rates of chemical fertilizers.

    PubMed

    Adesemoye, A O; Torbert, H A; Kloepper, J W

    2009-11-01

    The search for microorganisms that improve soil fertility and enhance plant nutrition has continued to attract attention due to the increasing cost of fertilizers and some of their negative environmental impacts. The objectives of this greenhouse study with tomato were to determine (1) if reduced rates of inorganic fertilizer coupled with microbial inoculants will produce plant growth, yield, and nutrient uptake levels equivalent to those with full rates of the fertilizer and (2) the minimum level to which fertilizer could be reduced when inoculants were used. The microbial inoculants used in the study were a mixture of plant growth-promoting rhizobacteria (PGPR) strains Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4, a formulated PGPR product, and the arbuscular mycorrhiza fungus (AMF), Glomus intraradices. Results showed that supplementing 75% of the recommended fertilizer rate with inoculants produced plant growth, yield, and nutrient (nitrogen and phosphorus) uptake that were statistically equivalent to the full fertilizer rate without inoculants. When inoculants were used with rates of fertilizer below 75% of the recommended rate, the beneficial effects were usually not consistent; however, inoculation with the mixture of PGPR and AMF at 70% fertility consistently produced the same yield as the full fertility rate without inoculants. Without inoculants, use of fertilizer rates lower than the recommended resulted in significantly less plant growth, yield, and nutrient uptake or inconsistent impacts. The results suggest that PGPR-based inoculants can be used and should be further evaluated as components of integrated nutrient management strategies.

  20. Mathematics Underground

    ERIC Educational Resources Information Center

    Luther, Kenneth H.

    2012-01-01

    Mathematical modeling of groundwater flow is a topic at the intersection of mathematics and geohydrology and is rarely encountered in undergraduate mathematics. However, this subject is full of interesting and meaningful examples of truly "applied" mathematics accessible to undergraduates, from the pre-calculus to advanced mathematics levels. This…

  1. Mathematics Underground

    ERIC Educational Resources Information Center

    Luther, Kenneth H.

    2012-01-01

    Mathematical modeling of groundwater flow is a topic at the intersection of mathematics and geohydrology and is rarely encountered in undergraduate mathematics. However, this subject is full of interesting and meaningful examples of truly "applied" mathematics accessible to undergraduates, from the pre-calculus to advanced mathematics levels. This…

  2. Electric Current Activated Combustion Synthesis and Chemical Ovens Under Terrestrial and Reduced Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Unuvar, C.; Fredrick, D.; Anselmi-Tamburini, U.; Manerbino, A.; Guigne, J. Y.; Munir, Z. A.; Shaw, B. D.

    2004-01-01

    Combustion synthesis (CS) generally involves mixing reactants together (e.g., metal powders) and igniting the mixture. Typically, a reaction wave will pass through the sample. In field activated combustion synthesis (FACS), the addition of an electric field has a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product as well as capillary flow, mass-transport in porous media, and Marangoni flows, which are influenced by gravity. The objective is to understand the role of an electric field in CS reactions under conditions where gravity-related effects are suppressed or altered. The systems being studied are Ti+Al and Ti+3Al. Two different ignition orientations have been used to observe effects of gravity when one of the reactants becomes molten. This consequentially influences the position and concentration of the electric current, which in turn influences the entire process. Experiments have also been performed in microgravity conditions. This process has been named Microgravity Field Activated Combustion Synthesis (MFACS). Effects of gravity have been demonstrated, where the reaction wave temperature and velocity demonstrate considerable differences besides the changes of combustion mechanisms with the different high currents applied. Also the threshold for the formation of a stable reaction wave is increased under zero gravity conditions. Electric current was also utilized with a chemical oven technique, where inserts of aluminum with minute amounts of tungsten and tantalum were used to allow observation of effects of settling of the higher density solid particles in liquid aluminum at the present temperature profile and wave velocity of the reaction.

  3. A simple chemical method reduces ochratoxin A in contaminated cocoa shells.

    PubMed

    Amézqueta, S; González-Peñas, E; Lizarraga, T; Murillo-Arbizu, M; López de Cerain, A

    2008-07-01

    Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium species, which contaminates cocoa among other food commodities. It has been previously demonstrated that the toxin is concentrated in cocoa shells. The aim of this study was to assay a simple chemical method for ochratoxin A reduction from naturally contaminated cocoa shells. In order to determine the efficiency of the method, a high-performance liquid chromatography method with fluorescence detection was set up beforehand and validated. Ochratoxin A was extracted from cocoa shells with methanol-3% sodium bicarbonate solution and then purified with immunoaffinity columns. The recovery attained was 88.7% (relative standard deviation = 6.36%) and the limits of detection and quantification were 0.06 and 0.2 kg/kg, respectively. For decontamination experiments, the solvent extractor ASE 200 was used. First, aqueous solutions of 2% sodium bicarbonate and potassium carbonate were compared under the same conditions (1,500 lb/in2 at 40 degrees C for 10 min). Higher ochratoxin A reduction was obtained with potassium carbonate (83 versus 27%). Then, this salt was used under different conditions of pressure, temperature, and time. The greatest ochratoxin A reduction was achieved with an aqueous potassium carbonate solution (2%), at 1,000 lb/in2 at 90 degrees C for 10 min. This method could probably be applicable to the cocoa industry because it is fast and relatively economic. From the point of view of human health, the use of potassium carbonate, partially eliminated by rinsing the sample with water, does not likely represent a risk for human health.

  4. Chemical vapor deposition of hexagonal boron nitride films in the reduced pressure

    SciTech Connect

    Choi, B.J.

    1999-12-01

    Hexagonal boron nitride (h-BN) films were deposited onto a graphite substrate in reduced pressure by reacting ammonia and boron tribromide at 800--1,200 C. The growth rate of h-BN films was dependent on the substrate temperature and the total pressures. The growth rate increased with increasing the substrate temperature at the pressure of 2 kPa, while it showed a maximum value at the pressures of 4 and 8 kPa. The temperature at which the maximum growth rate occurs decreased with increasing total pressure. With increasing the substrate temperature and total pressure, the apparent grain size increased and the surface morphology showed a rough, cauliflower-like structure.

  5. Physical and chemical evolution of reduced organic matter in the ISM

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Blake, David F.

    1995-01-01

    Icy mantles on interstellar grains have been a topic of study in airborne astronomy. Recent laboratory analog studies of the yield of organic residue from UV photolyzed ices have shown that this mechanism can be the most significant source of complex reduced organic matter in the interstellar medium. However, the total yield is a function of the occurrence of heating events that evaporate the ice, i.e. T is greater than 130 K, and the mechanism for such events is debated. Recently, we proposed that the recombination of radicals in the ice does not need high temperature excursions and, instead, occurs during a structural transformation of water ice at temperatures in the range 38 - 68 K.

  6. Chemical Inhibition of Kynureninase Reduces Pseudomonas aeruginosa Quorum Sensing and Virulence Factor Expression.

    PubMed

    Kasper, Stephen H; Bonocora, Richard P; Wade, Joseph T; Musah, Rabi Ann; Cady, Nathaniel C

    2016-04-15

    The opportunistic pathogen Pseudomonas aeruginosa utilizes multiple quorum sensing (QS) pathways to coordinate an arsenal of virulence factors. We previously identified several cysteine-based compounds inspired by natural products from the plant Petiveria alliacea which are capable of antagonizing multiple QS circuits as well as reducing P. aeruginosa biofilm formation. To understand the global effects of such compounds on virulence factor production and elucidate their mechanism of action, RNA-seq transcriptomic analysis was performed on P. aeruginosa PAO1 exposed to S-phenyl-l-cysteine sulfoxide, the most potent inhibitor from the prior study. Exposure to this inhibitor down-regulated expression of several QS-regulated virulence operons (e.g., phenazine biosynthesis, type VI secretion systems). Interestingly, many genes that were differentially regulated pertain to the related metabolic pathways that yield precursors of pyochelin, tricarboxylic acid cycle intermediates, phenazines, and Pseudomonas quinolone signal (PQS). Activation of the MexT-regulon was also indicated, including the multidrug efflux pump encoded by mexEF-oprN, which has previously been shown to inhibit QS and pathogenicity. Deeper investigation of the metabolites involved in these systems revealed that S-phenyl-l-cysteine sulfoxide has structural similarity to kynurenine, a precursor of anthranilate, which is critical for P. aeruginosa virulence. By supplementing exogenous anthranilate, the QS-inhibitory effect was reversed. Finally, it was shown that S-phenyl-l-cysteine sulfoxide competitively inhibits P. aeruginosa kynureninase (KynU) activity in vitro and reduces PQS production in vivo. The kynurenine pathway has been implicated in P. aeruginosa QS and virulence factor expression; however, this is the first study to show that targeted inhibition of KynU affects P. aeruginosa gene expression and QS, suggesting a potential antivirulence strategy.

  7. Phosphorus sequestration by chemical amendments to reduce leaching from wastewater applications.

    PubMed

    Zvomuya, Francis; Rosen, Carl J; Gupta, Satish C

    2006-01-01

    Phosphorus-immobilizing amendments can be useful in minimizing P leaching from high P soils that may be irrigated with wastewater. This study tested the P-binding ability of various amendment materials in a laboratory incubation experiment and then tested the best amendment in a field setup using drainage lysimeters. The laboratory experiment involved incubating 100-g samples of soil (72 mg kg(-1) water-extractable phosphorus, WEP) with various amendments at different rates for 63 d at field moisture capacity and 25 degrees C. The amendments tested were alum [Al2SO4)3.14H2O], ferric chloride (FeCl3), calcium carbonate (CaCO3), water treatment residual (WTR), and sugarbeet lime (SBL). Ferric chloride and alum at rates of 1.5 and 3.9 g kg(-1), respectively, were the most effective amendments that decreased WEP to 20 mg kg(-1), below which leaching has previously been shown to be low. Alum (1.3 kg m(-2)), which is less sensitive to redox conditions, was subsequently tested under field conditions, where it reduced WEP concentration in the 0- to 0.15-m layer from 119 mg kg(-1) on Day 0 to 36.1 mg kg(-1) (85% decrease) on Day 41. Lysimeter breakthrough tests using tertiary-treated potato-processing wastewater (mean total phosphorus [TP] = 3.4 mg L(-1)) showed that alum application reduced leachate TP and soluble reactive phosphorus (SRP) concentrations by 27 and 25%, respectively. These results indicate that alum application may be an effective strategy to immobilize P in high P coarse-textured soils. The relatively smaller decreases in TP and SRP in the leachate compared to WEP suggest some of the P may be coming from depths below 0.2 m. Thus, to achieve higher P sequestration, deeper incorporation of the alum may be necessary.

  8. Perinatal exposure to mixtures of endocrine disrupting chemicals reduces female rat follicle reserves and accelerates reproductive aging.

    PubMed

    Johansson, Hanna Katarina Lilith; Jacobsen, Pernille Rosenskjold; Hass, Ulla; Svingen, Terje; Vinggaard, Anne Marie; Isling, Louise Krag; Axelstad, Marta; Christiansen, Sofie; Boberg, Julie

    2016-06-01

    Exposure to endocrine disrupting chemicals (EDCs) during development can have negative consequences later in life. In this study we investigated the effect of perinatal exposure to mixtures of human relevant EDCs on the female reproductive system. Rat dams were exposed to a mixture of phthalates, pesticides, UV-filters, bisphenol A, butylparaben, as well as paracetamol. The compounds were tested together (Totalmix) or in subgroups with anti-androgenic (AAmix) or estrogenic (Emix) potentials. Paracetamol was tested separately. In pre-pubertal rats, a significant reduction in primordial follicle numbers was seen in AAmix and PM groups, and reduced plasma levels of prolactin was seen in AAmix. In one-year-old animals, the incidence of irregular estrous cycles was higher after Totalmix-exposure and reduced ovary weights were seen in Totalmix, AAmix, and PM groups. These findings resemble premature ovarian insufficiency in humans, and raises concern regarding potential effects of mixtures of EDCs on female reproductive function.

  9. Efficiency of a stormwater detention pond in reducing loads of chemical and physical constituents in urban streamflow, Pinellas County, Florida

    USGS Publications Warehouse

    Kantrowitz, I.H.; Woodham, W.M.

    1995-01-01

    A multipurpose wet stormwater detention pond in Pinellas Park, Florida was studied to determine its effectiveness in reducing the load of selected water-quality constituents commonly found in urban streamflow. Water-quality samples, and data on streamflow and precipitation were collected at the outflow and principal inflow of detention area 3 on Saint Joe Creek. To compare the constituent loads entering and leaving the detention pond, flows and water quality were monitored simultaneously at the inflow and outflow sites for six storms, and were monitored intermittently during periods of base flow. Lodas od 19 selected chemical and physical constituents were determined. Because all the stormwater entering the detention pond was not measured at the inflow site, computed stormwater inflow loads were adjusted to account for loads from the unmonitored areas. The ratio of storm- water volume measured at the outflow site to stormwater volume measured at the inflow site was used to adjust inflow loads for individual storms. Pond efficiencies for selected water- quality constituents for each of the storms were estimated by dividing the difference in outflow and adjusted inflow loads by the adjusted inflow load. Stormwater loads of the major ions (chloride, calcium and bicarbonate) and dissolved solids at the outflow site exceeded loads at the inflow site, partly as a result of mixing with base flow stored within the pond. However, the detention pond was effective in reducing the stormwater load of such urban-runoff contaminants as metals, nutrients, suspended solids, and biochemical and chemical oxygen demand. Estimated median pond efficiencies for reducing constituent loads ranged from 25 to more than 60 percent for metals, 2 to 52 percent for nutrients, 2 to 52 percent for nutrients, 7 to 11 percent for two measurements of suspended solids, and 16 to 49 percent for the oxygen- consuming substances. The reductions of constituent loads in stormwater are probably a result of

  10. Long-term incorporation of manure with chemical fertilizers reduced total nitrogen loss in rain-fed cropping systems

    NASA Astrophysics Data System (ADS)

    Duan, Yinghua; Xu, Minggang; Gao, Suduan; Liu, Hua; Huang, Shaomin; Wang, Boren

    2016-09-01

    Improving soil fertility/productivity and reducing environmental impact of nitrogen (N) fertilization are essential for sustainable agriculture. Quantifying the contribution of various fertilization regimes to soil N storage and loss has been lacking in a wide range of spatiotemporal scales. Based on data collected from field experiments at three typical agricultural zones in China, soil N dynamics and N changes in soil profile (0-100 cm) were examined during 1990-2009 under chemical fertilization, manure incorporation with fertilizer, and fertilizer with straw return treatments. We employed a mass balance approach to estimate the N loss to the environment after taking into account soil N change. Results showed a significant increase in soil N storage under manure incorporation treatments, accompanied with the lowest N loss (ave.20-24% of total N input) compared to all other treatments (ave.35-63%). Both soil N distribution and mass balance data suggested higher leaching risk from chemical fertilization in acidic soil of southern China with higher precipitation than the other two sites. This research concludes that manure incorporation with chemical fertilizer not only can achieve high N use efficiency and improve soil fertility, but also leads to the lowest total N loss or damage to the environment.

  11. Long-term incorporation of manure with chemical fertilizers reduced total nitrogen loss in rain-fed cropping systems

    PubMed Central

    Duan, Yinghua; Xu, Minggang; Gao, Suduan; Liu, Hua; Huang, Shaomin; Wang, Boren

    2016-01-01

    Improving soil fertility/productivity and reducing environmental impact of nitrogen (N) fertilization are essential for sustainable agriculture. Quantifying the contribution of various fertilization regimes to soil N storage and loss has been lacking in a wide range of spatiotemporal scales. Based on data collected from field experiments at three typical agricultural zones in China, soil N dynamics and N changes in soil profile (0–100 cm) were examined during 1990–2009 under chemical fertilization, manure incorporation with fertilizer, and fertilizer with straw return treatments. We employed a mass balance approach to estimate the N loss to the environment after taking into account soil N change. Results showed a significant increase in soil N storage under manure incorporation treatments, accompanied with the lowest N loss (ave.20–24% of total N input) compared to all other treatments (ave.35–63%). Both soil N distribution and mass balance data suggested higher leaching risk from chemical fertilization in acidic soil of southern China with higher precipitation than the other two sites. This research concludes that manure incorporation with chemical fertilizer not only can achieve high N use efficiency and improve soil fertility, but also leads to the lowest total N loss or damage to the environment. PMID:27650801

  12. Chemical genoprotection: reducing biological damage to as low as reasonably achievable levels

    PubMed Central

    Alcaraz, M; Armero, D; Martínez-Beneyto, Y; Castillo, J; Benavente-García, O; Fernandez, H; Alcaraz-Saura, M; Canteras, M

    2011-01-01

    Objectives The aim of this study was to evaluate the antioxidant substances present in the human diet with an antimutagenic protective capacity against genotoxic damage induced by exposure to X-rays in an attempt to reduce biological damage to as low a level as reasonably possible. Methods Ten compounds were assessed using the lymphocyte cytokinesis-block micronucleus (MN) cytome test. The compounds studied were added to human blood at 25 μM 5 min before exposure to irradiation by 2 Gy of X-rays. Results The protective capacity of the antioxidant substances assessed was from highest to lowest according to the frequency of the MN generated by X-ray exposure: rosmarinic acid = carnosic acid = δ-tocopherol = l-acid ascorbic = apigenin = amifostine (P < 0.001) > green tea extract = diosmine = rutin = dimetylsulfoxide (P < 0.05) > irradiated control. The reduction in genotoxic damage with the radiation doses administered reached 58%, which represents a significant reduction in X-ray-induced chromosomal damage (P < 0.001). This degree of protection is greater than that obtained with amifostine, a radioprotective compound used in radiotherapy and which is characterised by its high toxicity. Conclusion Several antioxidant substances, common components of the human diet and lacking toxicity, offer protection from the biological harm induced by ionizing radiation. Administering these protective substances to patients before radiological exploration should be considered, even in the case of small radiation doses and regardless of the biological damage expected. PMID:21697157

  13. Cancer prevention: Application of chemicals in treatment therapy to reduce risk in secondary tumor induction

    SciTech Connect

    Grdina, D.J.

    1986-01-01

    We have investigated WR2721 and similar aminothiol compounds to determine their role in modulating the mutagenic and carcinogenic action of radiation and selected chemotherapeutic agents. We have found that 2-((aminopropyl)amino) ethanethiol (WR1065), a free-thiol of WR2721, effectively protected against the mutagenic effects of radiation at the HGPRT locus in V79 cells even if administered up to 3 h following irradiation, a reduction in mutation frequencies of about 0.55. Under the conditions tested, the radioprotector protected against cell killing only if it was present during irradiation. In contrast, protection against mutagenesis occurred regardless of whether the protector was present during or following irradiation. These preliminary studies were expanded to determine the effects of WR1065 on cis-diamminedichloroplatinum-(cis-DDP) and bleomycin-induced cytotoxicity and mutagenicity even when administered following chemotherapy treatment. Thus, the V79 cell system used was found to be extremely effective in monitoring, in a rapid and cost-effective manner, the antimutagenic effects of radioprotectors on radiation and chemotherapy agents. Cell transformation was assayed using C3H 10T1/2 cells. The presence of a radioprotector significantly reduced the formation of radiation-induced transformed cells. Neonatal rats were also used to assess the induction of preneoplastic-lesions. 6 figs., 1 tab.

  14. Chemical genoprotection: reducing biological damage to as low as reasonably achievable levels.

    PubMed

    Alcaraz, M; Armero, D; Martínez-Beneyto, Y; Castillo, J; Benavente-García, O; Fernandez, H; Alcaraz-Saura, M; Canteras, M

    2011-07-01

    The aim of this study was to evaluate the antioxidant substances present in the human diet with an antimutagenic protective capacity against genotoxic damage induced by exposure to X-rays in an attempt to reduce biological damage to as low a level as reasonably possible. Ten compounds were assessed using the lymphocyte cytokinesis-block micronucleus (MN) cytome test. The compounds studied were added to human blood at 25 μM 5 min before exposure to irradiation by 2 Gy of X-rays. The protective capacity of the antioxidant substances assessed was from highest to lowest according to the frequency of the MN generated by X-ray exposure: rosmarinic acid = carnosic acid = δ-tocopherol = l-acid ascorbic = apigenin = amifostine (P < 0.001) > green tea extract = diosmine = rutin = dimetylsulfoxide (P < 0.05) > irradiated control. The reduction in genotoxic damage with the radiation doses administered reached 58%, which represents a significant reduction in X-ray-induced chromosomal damage (P < 0.001). This degree of protection is greater than that obtained with amifostine, a radioprotective compound used in radiotherapy and which is characterised by its high toxicity. Several antioxidant substances, common components of the human diet and lacking toxicity, offer protection from the biological harm induced by ionizing radiation. Administering these protective substances to patients before radiological exploration should be considered, even in the case of small radiation doses and regardless of the biological damage expected.

  15. Thrombospondin-2 overexpression in the skin of transgenic mice reduces the susceptibility to chemically-induced multistep skin carcinogenesis

    PubMed Central

    Kunstfeld, Rainer; Hawighorst, Thomas; Streit, Michael; Hong, Young-Kwon; Nguyen, Lynh; Brown, Lawrence F.; Detmar, Michael

    2014-01-01

    Background We have previously reported stromal upregulation of the endogenous angiogenesis inhibitor thrombospondin-2 (TSP-2) during multistep carcinogenesis, and we found accelerated and enhanced skin angiogenesis and carcinogenesis in TSP-2 deficient mice. Goals To investigate whether enhanced levels of TSP-2 might protect from skin cancer development. Methods We established transgenic mice with targeted overexpression of TSP-2 in the skin and subjected hemizygous TSP-2 transgenic mice and their wild-type littermates to a chemical skin carcinogenesis regimen. Results TSP-2 transgenic mice showed a significantly delayed onset of tumor formation compared to wild-type mice, whereas the ratio of malignant conversion to squamous cell carcinomas was comparable in both genotypes. Computer-assisted morphometric analysis of blood vessels revealed pronounced tumor angiogenesis already in the early stages of carcinogenesis in wild type mice. TSP-2 overexpression significantly reduced tumor blood vessel density in transgenic mice but had no overt effect on LYVE-1 positive lymphatic vessels. The percentage of desmin surrounded, mature tumor-associated blood vessels and the degree of epithelial differentiation remained unaffected. The antiangiogenic effect of transgenic TSP-2 was accompanied by a significantly increased number of apoptotic tumor cells in transgenic mice. Conclusion Our results demonstrate that enhanced levels of TSP-2 in the skin result in reduced susceptibility to chemically-induced skin carcinogenesis and identify TSP-2 as a new target for the prevention of skin cancer. PMID:24507936

  16. Investigation of chemical rinses suitable for very small meat plants to reduce pathogens on beef surfaces.

    PubMed

    Yoder, Sally F; Henning, William R; Mills, Edward W; Doores, Stephanie; Ostiguy, Nancy; Cutter, Catherine N

    2012-01-01

    Numerous antimicrobial interventions are capable of reducing the prevalence of harmful bacteria on raw meat products. There is a need to identify effective and inexpensive antimicrobial interventions that could, in practice, be used in very small meat plants because of limited financial, space, and labor resources. Eight antimicrobial compounds (acetic acid, citric acid, lactic acid, peroxyacetic acid, acidified sodium chlorite, chlorine dioxide, sodium hypochlorite, and aqueous ozone) were applied at various concentrations with small, hand-held spraying equipment, and bactericidal effectiveness was examined. Beef plate pieces were inoculated with fecal slurry containing a pathogen cocktail (Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter coli, and Campylobacter jejuni) and natural populations of aerobic plate counts, coliforms, and E. coli. Antimicrobial solutions were applied to beef surfaces via a portable, pressurized hand-held spray tank, and treated surfaces were subjected to appropriate methods for the enumeration and isolation of pathogens and hygiene indicators. Relative antimicrobial effectiveness was determined (from greatest to least): (i) organic acids, (ii) peroxyacetic acid, (iii) chlorinated compounds, and (iv) aqueous ozone. Using the equipment described, a 2% lactic acid rinse provided 3.5- to 6.4-log CFU/cm(2) reductions across all bacterial populations studied. Conversely, aqueous ozone yielded 0.02- to 2.9-log CFU/cm(2) reductions in pathogens and hygiene indicators, and did not differ significantly from a control tap water rinse (P = 0.055 to 0.731). This 2% lactic acid rinse will be subsequently combined with a previously described water wash to create a multistep antimicrobial intervention that will be examined under laboratory conditions and validated in very small meat plants.

  17. Reversible control of the chromium valence in chemically reduced Cr-doped SrTiO3 bulk powders.

    PubMed

    Lehuta, Keith A; Kittilstved, Kevin R

    2016-06-14

    The effect of chemical reduction by NaBH4 on the electronic structure of Cr-doped SrTiO3-δ bulk powders prepared by a solid-state reaction was systematically studied as a function of reduction temperature. Electron paramagnetic resonance (EPR) and diffuse reflectance spectroscopies (DRS) were utilized to monitor changes in the electronic structures of both intrinsic defects (oxygen vacancies and/or Ti(3+)) and extrinsic dopants (Cr(3+)) at different reduction temperatures. We identify the existence of two temperature regimes where changes occur within 30 min. The first temperature regime occurs between 300-375 °C and results in (1) reduction of oxygen-related surface defects, and (2) an increase in the concentration of Cr(3+) by over an order of magnitude, suggesting that EPR-silent Cr(4+) or Cr(6+) is being reduced to Cr(3+) by NaBH4. The second temperature regime occurs between 375-430 °C where we observe clear evidence of Ti(3+) formation by EPR spectroscopy that indicates chemical reduction of the SrTiO3 lattice. In addition, the oxygen-related surface defects observed in regime 1 are not formed in regime 2, but instead lattice oxygen vacancies (VO) are observed by EPR. The changes to the Cr-doped SrTiO3 electronic structure after chemical reduction in regime 1 are quantitatively reversible after aerobic annealing at 400 °C for 30 min. The internal oxygen vacancies formed during the higher temperature reductions in regime 2 require increased temperatures of at least 600 °C to be fully reoxidized in 30 min. The effect of these different oxygen-related defects on the EPR spectrum of substitutional Cr(3+) dopants is discussed. These results allow us to independently tune the dopant and host electronic structures of a technologically-relevant multifunctional material by a simple ex situ chemical perturbation.

  18. Reduced Sulfur in Ashes and Slags from the Gasification of Coals: Availability for Chemical and Microbial Oxidation †

    PubMed Central

    Strayer, Richard F.; Davis, Edward C.

    1983-01-01

    This study was initiated to determine if reduced sulfur contained in coal gasifier ash and slag was available for microbial and chemical oxidation because eventual large-quantity landfill disposal of these solid wastes is expected. Continuous application of distilled water to a column containing a high-sulfur-content (4% [wt/wt]) gasifier slag yielded leachates with high sulfate levels (1,300 mg of sulfate liter−1) and low pH values (4.2). At the end of the experiment, a three-tube most-probable-number analysis indicated that the waste contained 1.3 × 107 thiosulfate-oxidizing bacteria per g. Slag samples obtained aseptically from the column produced sulfate under both abiotic and biotic conditions when incubated in a mineral nutrient solution. Both microbial and chemical sulfate syntheses were greatly stimulated by the addition of thiosulfate to the slag-mineral nutrient solution. These results led to a test of microbial versus chemical sulfur oxidation in ashes and slags from five gasification processes. Sulfate production was measured in sterile (autoclaved) and nonsterile suspensions of the solid wastes in a mineral nutrient solution. These ashes and slags varied in sulfur content from 0.3 to 4.0% (wt/wt). Four of these wastes demonstrated both chemical (2.0 to 27 μg of sulfate g−1 day−1) and microbial (3.1 to 114 μg of sulfate g−1 day−1) sulfur oxidation. Obvious relationships between sulfur oxidation rate and either sulfur content or particle size distribution of the wastes were not immediately evident. We conclude that the sulfur contained in all but one waste is available for oxidation to sulfuric acid and that microorganisms play a partial role in this process. PMID:16346240

  19. Biodegradation reduces magnetization in oil bearing rocks: magnetization results of a combined chemical and magnetic study

    NASA Astrophysics Data System (ADS)

    Emmerton, S.; Muxworthy, A. R.; Sephton, M. A.; Williams, W.

    2012-12-01

    dominance of multidomain magnetite as well as the appearance of hematite. The presence of hematite only within heavily biodegraded samples suggests a later stage of biodegradation at the surface due to oxidation of magnetite. We have identified a relationship between magnetization and the relative abundance of aliphatic organic compounds in oil. Biodegradation appears to remove both aliphatic hydrocarbons and magnetic susceptibility owing to influence of bacterial metabolic activity that uses ferric iron minerals as electron acceptors reducing the overall magnetic signature. These findings reinforce the importance of bacteria within petroleum systems as well as providing a platform for the use of magnetization as a hydrocarbon migration proxy and as an inexpensive and simple method to determine oil quality.

  20. Mathematical Assessment of Physical and Chemical Processes from the middle B to the early F Type Main Sequence Stars

    NASA Astrophysics Data System (ADS)

    Yuce, Kutluay; Adelman, Saul J.

    2016-07-01

    The middle B to the early F main sequence stars are thought to have some of the most quiet atmospheres. In this part of the HR diagram we find stars with atmospheres in radiative equilibrium. They lack the convective circulations of the middle F and cooler stars and the massive stellar winds of hotter stars. Diffusion theory requires the Chemically Peculiar stars to have relatively quiet atmospheres and if there are no magnetic fields they should lack abundance spots. If we look at stars evolving off the Main Sequence in this part of the HR diagram, we see that the evolutionary paths of stars of different mass do not cross. So if we compare stars with the same effective temperature and surface gravity, we are studying stars of the same luminosity and mass. By comparing their elemental abundances, we might be able to identify physical processes which cause their abundances to be different. In this work we begin with stars whose effective temperatures and surface gravities are similar, and which has been analyzed by us using spectra obtained from the Dominion Astrophysical Observatory.

  1. The Role of STEM High Schools in Reducing Gaps in Science and Mathematics Coursetaking: Evidence from North Carolina. Research Report. RTI Press Publication RR-0025-1603

    ERIC Educational Resources Information Center

    Glennie, Elizabeth; Mason, Marcinda; Dalton, Ben

    2016-01-01

    Some states have created science, technology, engineering, and mathematics (STEM) schools to encourage student interest and enhance student proficiency in STEM subjects. We examined a set of STEM schools serving disadvantaged students to see whether these students were more likely to take and pass advanced science and mathematics classes than…

  2. Chemical modification of peanut conglutin reduces IgE reactivity but not T cell reactivity in peanut-allergic patients.

    PubMed

    van Hoffen, E; van der Kleij, H P M; den Hartog Jager, C F; van Doorn, W A; Knol, E F; Opstelten, D-J; Koppelman, S J; Knulst, A C

    2014-12-01

    Specific immunotherapy for peanut allergy is associated with significant side-effects. Chemically modified allergens may provide a safer alternative. This study aimed to analyse the immunogenicity and allergenicity of modified peanut conglutin. Native peanut conglutin and two modifications thereof were generated (RA and RAGA). Conglutin-specific T cell lines from 11 peanut-allergic patients were analysed for proliferation and cytokine production. Sera from 14 patients were analysed for IgE/IgG1/IgG4 binding by immunoblot and ELISA. IgE reactivity was analysed by direct and indirect basophil activation test (BAT), in presence and absence of patient plasma or CD32-blocking antibodies. T cell proliferation to RA was unchanged, and proliferation to RAGA was reduced compared to native conglutin. Cytokine profiles remained unchanged. IgE, IgG1 and IgG4 binding to RA and RAGA was significantly reduced. In the direct BAT, the relative potency of modified conglutin was decreased in 67% and increased/similar in 33% of the patients. In the indirect BAT, RA and RAGA were 10-100 times less potent than native conglutin. Addition of plasma to the indirect BAT increased the relative potency of modified conglutin in patients with high peanut-specific IgG levels. This was mediated via blocking of the response to native conglutin, most likely by soluble IgG, and not via CD32. Chemical modification of peanut conglutin by RA retains immunogenicity and reduces allergenicity and may be a promising approach for development of a curative treatment for peanut allergy. In a subgroup of patients, where the reactivity of native conglutin is already partially blocked by IgG, the effect of the modification of conglutin is less pronounced. © 2014 John Wiley & Sons Ltd.

  3. Mathematics, Anyone?

    ERIC Educational Resources Information Center

    Reys, Robert; Reys, Rustin

    2011-01-01

    In their dual roles as mathematics teachers and tennis coaches, the authors have worked with tennis players who have never thought about how a knowledge of mathematics might help them become "better" tennis players. They have also worked with many mathematics students who have never considered how much mathematics is associated with tennis. This…

  4. Mathematics, Anyone?

    ERIC Educational Resources Information Center

    Reys, Robert; Reys, Rustin

    2011-01-01

    In their dual roles as mathematics teachers and tennis coaches, the authors have worked with tennis players who have never thought about how a knowledge of mathematics might help them become "better" tennis players. They have also worked with many mathematics students who have never considered how much mathematics is associated with tennis. This…

  5. Successions and diversity of humic-reducing microorganisms and their association with physical-chemical parameters during composting.

    PubMed

    Xi, Beidou; Zhao, Xinyu; He, Xiaosong; Huang, Caihong; Tan, Wenbing; Gao, Rutai; Zhang, Hui; Li, Dan

    2016-11-01

    Humic-reducing microorganisms (HRMs) could utilize humic substances (HS) as terminal electron mediator to promote the biodegradation of recalcitrant pollutants. However, the dynamics of HRMs during composting has not been explored. Here, high throughput sequencing technology was applied to investigate the patterns of HRMs during three composting systems. A total of 30 main genera of HRMs were identified in three composts, with Proteobacteria being the largest phylum. HRMs were detected with increased diversity and abundance and distinct patterns during composting, which were significantly associated with dissolved organic carbon, dissolved organic nitrogen and germination index. Regulating key physical-chemical parameters is a process control of HRMs community composition, thus promoting the redox capability of the compost. The redox capability of HRMs were strengthened during composting, suggesting that HRMs of the compost may play an important role on pollutant degradation of the compost or when they are applied to the contaminated soils.

  6. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    SciTech Connect

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  7. Reduced-Pressure Chemical Vapor Deposition Growth of Isolated Ge Crystals and Suspended Layers on Micrometric Si Pillars.

    PubMed

    Skibitzki, Oliver; Capellini, Giovanni; Yamamoto, Yuji; Zaumseil, Peter; Schubert, Markus Andreas; Schroeder, Thomas; Ballabio, Andrea; Bergamaschini, Roberto; Salvalaglio, Marco; Miglio, Leo; Montalenti, Francesco

    2016-10-05

    In this work, we demonstrate the growth of Ge crystals and suspended continuous layers on Si(001) substrates deeply patterned in high aspect-ratio pillars. The material deposition was carried out in a commercial reduced-pressure chemical vapor deposition reactor, thus extending the "vertical-heteroepitaxy" technique developed by using the peculiar low-energy plasma-enhanced chemical vapor deposition reactor, to widely available epitaxial tools. The growth process was thoroughly analyzed, from the formation of small initial seeds to the final coalescence into a continuous suspended layer, by means of scanning and transmission electron microscopy, X-ray diffraction, and μ-Raman spectroscopy. The preoxidation of the Si pillar sidewalls and the addition of hydrochloric gas in the reactants proved to be key to achieve highly selective Ge growth on the pillars top only, which, in turn, is needed to promote the formation of a continuous Ge layer. Thanks to continuum growth models, we were able to single out the different roles played by thermodynamics and kinetics in the deposition dynamics. We believe that our findings will open the way to the low-cost realization of tens of micrometers thick heteroepitaxial layer (e.g., Ge, SiC, and GaAs) on Si having high crystal quality.

  8. Rapid-mix and chemical quench studies of ferredoxin-reduced stearoyl-acyl carrier protein desaturase.

    PubMed

    Lyle, Karen S; Haas, Jeffrey A; Fox, Brian G

    2003-05-20

    Stearoyl-ACP Delta9 desaturase (Delta9D) catalyzes the NADPH- and O(2)-dependent insertion of a cis double bond between the C9 and C10 positions of stearoyl-ACP (18:0-ACP) to produce oleoyl-ACP (18:1-ACP). This work revealed the ability of reduced [2Fe-2S] ferredoxin (Fd) to act as a catalytically competent electron donor during the rapid conversion of 18:0-ACP into 18:1-ACP. Experiments on the order of addition for substrate and reduced Fd showed high conversion of 18:0-ACP to 18:1-ACP (approximately 95% per Delta9D active site in a single turnover) when 18:0-ACP was added prior to reduced Fd. Reactions of the prereduced enzyme-substrate complex with O(2) and the oxidized enzyme-substrate complex with reduced Fd were studied by rapid-mix and chemical quench methods. For reaction of the prereduced enzyme-substrate complex, an exponential burst phase (k(burst) = 95 s(-1)) of product formation accounted for approximately 90% of the turnover expected for one subunit in the dimeric protein. This rapid phase was followed by a slower phase (k(linear) = 4.0 s(-1)) of product formation corresponding to the turnover expected from the second subunit. For reaction of the oxidized enzyme-substrate complex with excess reduced Fd, a slower, linear rate (k(obsd) = 3.4 s(-1)) of product formation was observed over approximately 1.5 turnovers per Delta9D active site potentially corresponding to a third phase of reaction. An analysis of the deuterium isotope effect on the two rapid-mix reaction sequences revealed only a modest effect on k(burst) ((D)k(burst) approximately 1.5) and k(linear) (D)k(linear) approximately 1.4), indicating C-H bond cleavage does not contribute significantly to the rate-limiting steps of pre-steady-state catalysis. These results were used to assemble and evaluate a minimal kinetic model for Delta9D catalysis.

  9. Conductive reduced graphene oxide/MnO2 carbonized cotton fabrics with enhanced electro -chemical, -heating, and -mechanical properties

    NASA Astrophysics Data System (ADS)

    Tian, Mingwei; Du, Minzhi; Qu, Lijun; Zhang, Kun; Li, Hongliang; Zhu, Shifeng; Liu, Dongdong

    2016-09-01

    Versatile and ductile conductive carbonized cotton fabrics decorated with reduced graphene oxide (rGO)/manganese dioxide (MnO2) are prepared in this paper. In order to endow multifunction to cotton fabric, graphene oxide (GO) is deposited on cotton fibers by simple dip-coating route. MnO2 nanoparticles are assembled on the surface of cotton fabric through in-situ chemical solution deposition. MnO2/GO@cotton fabrics are carbonized to achieve conductive fabric (MnO2/rGO@C). The morphologies and structures of obtained fabrics are characterized by SEM, XRD, ICP and element analysis, and their electro-properties including electro-chemical, electro-heating and electro-mechanical properties are evaluated. The MnO2/rGO@C yields remarkable specific capacitance of 329.4 mA h/g at the current density of 100 mA/g, which is more than 40% higher than that of the control carbonized cotton fabric (231 mA h/g). Regarding electro-heating properties, the temperature of MnO2/rGO@C fabric could be monotonically increased to the steady-state maximum temperatures (ΔTmax) of 36 °C within 5 min under the applied voltage 15 V while the ΔTmax = 17 °C of the control case. In addition, MnO2/rGO@C exhibits repeatable electro-mechanical properties and its normalized resistance (R-R0)/R0 could reach 0.78 at a constant strain (curvature = 0.6 cm-1). The MnO2/rGO@C fabric is versatile, scalable, and adaptable to a wide variety of smart textiles applications.

  10. Mathematical modeling of drug delivery.

    PubMed

    Siepmann, J; Siepmann, F

    2008-12-08

    Due to the significant advances in information technology mathematical modeling of drug delivery is a field of steadily increasing academic and industrial importance with an enormous future potential. The in silico optimization of novel drug delivery systems can be expected to significantly increase in accuracy and easiness of application. Analogous to other scientific disciplines, computer simulations are likely to become an integral part of future research and development in pharmaceutical technology. Mathematical programs can be expected to be routinely used to help optimizing the design of novel dosage forms. Good estimates for the required composition, geometry, dimensions and preparation procedure of various types of delivery systems will be available, taking into account the desired administration route, drug dose and release profile. Thus, the number of required experimental studies during product development can be significantly reduced, saving time and reducing costs. In addition, the quantitative analysis of the physical, chemical and potentially biological phenomena, which are involved in the control of drug release, offers another fundamental advantage: The underlying drug release mechanisms can be elucidated, which is not only of academic interest, but a pre-requisite for an efficient improvement of the safety of the pharmaco-treatments and for effective trouble-shooting during production. This article gives an overview on the current state of the art of mathematical modeling of drug delivery, including empirical/semi-empirical and mechanistic realistic models. Analytical as well as numerical solutions are described and various practical examples are given. One of the major challenges to be addressed in the future is the combination of mechanistic theories describing drug release out of the delivery systems with mathematical models quantifying the subsequent drug transport within the human body in a realistic way. Ideally, the effects of the design

  11. Mathematic Terminology.

    ERIC Educational Resources Information Center

    Hanh, Vu Duc, Ed.

    This document gives a listing of mathematical terminology in both the English and Vietnamese languages. Vocabulary used in algebra and geometry is included along with a translation of mathematical symbols. (DT)

  12. Mathematical Geology.

    ERIC Educational Resources Information Center

    Jones, Thomas A.

    1983-01-01

    Mathematical techniques used to solve geological problems are briefly discussed (including comments on use of geostatistics). Highlights of conferences/meetings and conference papers in mathematical geology are also provided. (JN)

  13. Mathematical Misteaks

    ERIC Educational Resources Information Center

    Carman, Robert A.

    1971-01-01

    A mathematical misteak" is an incorrect operation that leads to a correct result. An introduction to the use of the misteak" to emphasize the mathematical operations being taught. Examples and brief explanations of several types of misteaks" are given. (FL)

  14. Mathematics disorder

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/001534.htm Mathematics disorder To use the sharing features on this page, please enable JavaScript. Mathematics disorder is a condition in which a child's ...

  15. Pediatric Cystic Fibrosis Sputum Can Be Chemically Dynamic, Anoxic, and Extremely Reduced Due to Hydrogen Sulfide Formation

    PubMed Central

    Cowley, Elise S.; Kopf, Sebastian H.; LaRiviere, Alejandro

    2015-01-01

    ABSTRACT Severe and persistent bacterial lung infections characterize cystic fibrosis (CF). While several studies have documented the microbial diversity within CF lung mucus, we know much less about the inorganic chemistry that constrains microbial metabolic processes and their distribution. We hypothesized that sputum is chemically heterogeneous both within and between patients. To test this, we measured microprofiles of oxygen and sulfide concentrations as well as pH and oxidation-reduction potentials in 48 sputum samples from 22 pediatric patients with CF. Inorganic ions were measured in 20 samples from 12 patients. In all cases, oxygen was depleted within the first few millimeters below the sputum-air interface. Apart from this steep oxycline, anoxia dominated the sputum environment. Different sputum samples exhibited a broad range of redox conditions, with either oxidizing (16 mV to 355 mV) or reducing (−300 to −107 mV) potentials. The majority of reduced samples contained hydrogen sulfide and had a low pH (2.9 to 6.5). Sulfide concentrations increased at a rate of 0.30 µM H2S/min. Nitrous oxide was detected in only one sample that also contained sulfide. Microenvironmental variability was observed both within a single patient over time and between patients. Modeling oxygen dynamics within CF mucus plugs indicates that anoxic zones vary as a function of bacterial load and mucus thickness and can occupy a significant portion of the mucus volume. Thus, aerobic respiration accounts only partially for pathogen survival in CF sputum, motivating research to identify mechanisms of survival under conditions that span fluctuating redox states, including sulfidic environments. PMID:26220964

  16. Chemical Transport and Reduced-Form Models for Assessing Air Quality Impacts of Current and Future Energy Scenarios

    NASA Astrophysics Data System (ADS)

    Adams, P. J.

    2015-12-01

    Though essential for informed decision-making, it is challenging to estimate the air quality and public health impacts associated with current and future energy generation scenarios because the analysis must address the complicated atmospheric processes that air pollutants undergo: emissions, dispersion, chemistry, and removal. Employing a chemical transport model (CTM) is the most rigorous way to address these atmospheric processes. However, CTMs are expensive from a computational standpoint and, therefore, beyond the reach of policy analysis for many types of problems. On the other hand, previously available reduced-form models used for policy analysis fall short of the rigor of CTMs and may lead to biased results. To address this gap, we developed the Estimating Air pollution Social Impacts Using Regression (EASIUR) method, which builds parameterizations that predict per-tonne social costs and intake fractions for pollutants emitted from any location in the United States. Derived from a large database of tagged CTM simulations, the EASIUR method predicts social costs almost indistinguishable from a full CTM but with negligible computational requirements. We found that the average mortality-related social costs from inorganic PM2.5 and its precursors in the United States are 150,000-180,000/t EC, 21,000-34,000/t SO2, 4,200-15,000/t NOx, and 29,000-85,000/t NH3. This talk will demonstrate examples of using both CTMs and reduced-form models for assessing air quality impacts associated with current energy production activities as well as a future deployment of carbon capture and sequestration.

  17. Rainforest Mathematics

    ERIC Educational Resources Information Center

    Kilpatrick, Jeremy

    2014-01-01

    This paper addresses the contested way that ethnomathematics has sometimes been received by mathematicians and others and what that disagreement might suggest about issues in mathematics education; namely, (a) the relation of ethnomathematics to academic mathematics; (b) recent efforts to reform secondary school mathematics so that it prepares…

  18. Rainforest Mathematics

    ERIC Educational Resources Information Center

    Kilpatrick, Jeremy

    2014-01-01

    This paper addresses the contested way that ethnomathematics has sometimes been received by mathematicians and others and what that disagreement might suggest about issues in mathematics education; namely, (a) the relation of ethnomathematics to academic mathematics; (b) recent efforts to reform secondary school mathematics so that it prepares…

  19. Silver Nanowire Embedded Colorless Polyimide Heater for Wearable Chemical Sensors: Improved Reversible Reaction Kinetics of Optically Reduced Graphene Oxide.

    PubMed

    Choi, Seon-Jin; Kim, Sang-Joon; Jang, Ji-Soo; Lee, Ji-Hyun; Kim, Il-Doo

    2016-09-14

    Optically reduced graphene oxide (ORGO) sheets are successfully integrated on silver nanowire (Ag NW)-embedded transparent and flexible substrate. As a heating element, Ag NWs are embedded in a colorless polyimide (CPI) film by covering Ag NW networks using polyamic acid and subsequent imidization. Graphene oxide dispersed aqueous solution is drop-coated on the Ag NW-embedded CPI (Ag NW-CPI) film and directly irradiated by intense pulsed light to obtain ORGO sheets. The heat generation property of Ag NW-CPI film is investigated by applying DC voltage, which demonstrates unprecedentedly reliable and stable characteristics even in dynamic bending condition. To demonstrate the potential application in wearable chemical sensors, NO2 sensing characteristic of ORGO is investigated with respect to the different heating temperature (22.7-71.7 °C) of Ag NW-CPI film. The result reveals that the ORGO sheets exhibit high sensitivity of 2.69% with reversible response/recovery sensing properties and minimal deviation of baseline resistance of around 1% toward NO2 molecules when the temperature of Ag NW-CPI film is 71.7 °C. This work first demonstrates the improved reversible NO2 sensing properties of ORGO sheets on flexible and transparent Ag NW-CPI film assisted by Ag NW heating networks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Chemical vapour deposition of silicon under reduced pressure in a hot-wall reactor: Equilibrium and kinetics

    NASA Astrophysics Data System (ADS)

    Langlais, Francis; Hottier, François; Cadoret, Robert

    1982-02-01

    Silicon chemical vapour deposition (SiH 2Cl 2/H 2 system), under reduced pressure conditions, in a hot-wall reactor, is presented. The vapour phase composition is assessed by evaluating two distnct equilbria. The "homogeneous equilibrium", which assumes that the vapour phase is not in equilibrium with solid silicon, is thought to give an adequate description of the vapour phase in the case of low pressure, high gas velocities, good temperature homogeneity conditions. A comparison with "heterogeneous equilibrium" enables us to calculate the supersaturation so evidencing a highly irreversible growth system. The experimental determination of the growth rate reveals two distinct temperature ranges: below 1000°C, polycrystalline films are usually obtained with a thermally activated growth rate (+40 kcal mole -1) and a reaction order, with respect to the predominant species SiCl 2, close to one; above 1000°C, the films are always monocrystalline and their growth rate exhibits a much lower or even negative activation energy, the reaction order in SiCl 2 remaining about one.

  1. Immobilizing of catalyst using Bayah's natural zeolite to reduce the chemical oxygen demand (COD) and total organic carbon (TOC)

    NASA Astrophysics Data System (ADS)

    Jayanudin, Kustiningsih, Indar; Sari, Denni Kartika

    2017-05-01

    Indonesia is rich of natural minerals, many of which had not been widely used. One potential natural mineral is zeolite from Bayah Banten that can be used to support catalyst in the process of waste degradation. The purpose of this research is to characterize the Bayah's zeolite and to figure out the effectiveness of the zeolite as supporting agent to the Fe catalyst in the process of phenol degradation, with the main purposes are to reduce the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC). This research consists of three steps, activation of natural zeolite using 1M, 2M, and 3M NaOH solution, impregnation process with 0.025M, 0.05 M and 0.075M Fe(NO3)3.9H2O solution, and calcination at 500°C. Bayah's natural zeolite was characterize using Brauner-Emmet-Teller (BET) for its pore area, X-ray Fluorescence (XRF) for analyzing zeolite's component before and after activation process and after impregnation process, and Scanning Electron Microscope (SEM) for analyzing zeolite's morphology. The result showed that the highest pore area was 9Å, Fe metal from Fe(NO3)3.9H2O 0,075 M solution remained in zeolite pore was 7,73%, the reduction of COD and TOC was yielded at H2O2: phenol ratio of 1 : 6.

  2. Mathematical Modeling and Pure Mathematics

    ERIC Educational Resources Information Center

    Usiskin, Zalman

    2015-01-01

    Common situations, like planning air travel, can become grist for mathematical modeling and can promote the mathematical ideas of variables, formulas, algebraic expressions, functions, and statistics. The purpose of this article is to illustrate how the mathematical modeling that is present in everyday situations can be naturally embedded in…

  3. Mathematical Modeling and Pure Mathematics

    ERIC Educational Resources Information Center

    Usiskin, Zalman

    2015-01-01

    Common situations, like planning air travel, can become grist for mathematical modeling and can promote the mathematical ideas of variables, formulas, algebraic expressions, functions, and statistics. The purpose of this article is to illustrate how the mathematical modeling that is present in everyday situations can be naturally embedded in…

  4. Hydrology and geochemistry of the uranium mill tailings pile at Riverton, Wyoming. Part II. History matching. [Mathematical simulation of the observed fluid potentials within the tailings, and the observed distribution of various chemical species within and around the mill tailings

    SciTech Connect

    Narasimhan, T.N.; White, A.F.; Tokunaga, T.

    1985-02-01

    In Part I of this series of two reports the observed fluid potential and geochemical characteristics in and around the inactive uranium mill tailings pile at Riverton, Wyoming were presented. The prupose of the present work is to attempt to simulate field observations using mathematical models. The results of the studies have not only helped identify the physicochemical mechanisms govering contaminant migration around the inactive mill tailings pile in Riverton, but also have indicated the feasibility of quantifying these mechanisms with the help of newly developed mathematical models. Much work needs to be done to validate and benchmark these models. The history-matching effort on hand involves the mathematical simulation of the observed fluid potentials within the tailings, and the observed distribution of various chemical species within and around the inactive uranium mill tailings. The simulation problem involves consideration of transient fluid flow and transient, reactive chemical transport in a variably saturated ground water system with time-dependent boundary conditions. 15 refs., 30 figs., 3 tabs.

  5. Chemical and plant tests to assess the viability of amendments to reduce metal availability in mine soils and tailings.

    PubMed

    Rodríguez, Luis; Gómez, Rocío; Sánchez, Virtudes; Alonso-Azcárate, Jacinto

    2016-04-01

    The goal of this research was to assess the potential of several industrial wastes to immobilise metals in two polluted soils deriving from an old Pb/Zn mine. Two different approaches were used to assess the performance of different amendments: a chemical one, using extraction by ethylenediaminetetraacetic acid (EDTA), and a biological one, using Lupinus albus as a bio-indicator. Four amendments were used: inorganic sugar production waste (named 'sugar foam', SF), sludge from a drinking water treatment sludge (DWS), organic waste from olive mill waste (OMW) and paper mill sludge (PMS). Amendment to soil ratios ranged from 0.1 to 0.3 (w/w). All the amendments were capable of significantly decreasing (p < 0.05) EDTA-extractable Pb, Zn and Cu concentrations in the two soils used, with decreases in ranges 21-100, 25-100 and 2-100 % for Pb, Zn and Cu, respectively. The amendments tested were also effective in reducing the bioavailability of Pb and Zn for L. albus, which gave rise to a decrease in shoot metal accumulation by the lupine plants compared to that found in the control soil. That decrease reached up to 5.6 and 2.8 times for Pb and Zn, respectively, being statistically significant in most cases. Moreover, application of the OMW, DWS and SF amendments led to higher average values of plant biomass (up to 71%) than those obtained in the control soil. The results obtained showed the technology put forward to be a viable means of remediating mine soils as it led to a decrease in the availability and toxicity of metals and, thus, facilitated the growth of a vegetation layer.

  6. Spatial pattern assessment of river water quality: implications of reducing the number of monitoring stations and chemical parameters.

    PubMed

    Wang, Yeuh-Bin; Liu, Chen-Wuing; Liao, Pei-Yu; Lee, Jin-Jing

    2014-03-01

    The Tamsui River basin is located in Northern Taiwan and encompasses the most metropolitan city in Taiwan, Taipei City. The Taiwan Environmental Protection Administration (EPA) has established 38 water quality monitoring stations in the Tamsui River basin and performed regular river water quality monitoring for the past two decades. Because of the limited budget of the Taiwan EPA, adjusting the monitoring program while maintaining water quality data is critical. Multivariate analysis methods, such as cluster analysis (CA), factor analysis (FA), and discriminate analysis (DA), are useful tools for the statistically spatial assessment of surface water quality. This study integrated CA, FA, and DA to evaluate the spatial variance of water quality in the metropolitan city of Taipei. Performing CA involved categorizing monitoring stations into three groups: high-, moderate-, and low-pollution areas. In addition, this categorization of monitoring stations was in agreement with that of the assessment that involved using the simple river pollution index. Four latent factors that predominantly influence the river water quality of the Tamsui River basin are assessed using FA: anthropogenic pollution, the nitrification process, seawater intrusion, and geological and weathering processes. We plotted a spatial pattern using the four latent factor scores and identified ten redundant monitoring stations near each upstream station with the same score pattern. We extracted five significant parameters by using DA: total organic carbon, total phosphorus, As, Cu, and nitrate, with spatial variance to differentiate them from the polluted condition of the group obtained by using CA. Finally, this study suggests that the Taiwan EPA can adjust the surface water-monitoring program of the Tamsui River by reducing the monitoring stations to 28 and the measured chemical parameters to five to lower monitoring costs.

  7. Chemical, ultrastructural and supramolecular analysis of tension wood in Populus tremula x alba as a model substrate for reduced recalcitrance

    SciTech Connect

    Foston, Marcus B; Hubbell, Christopher A; Samuel, Reichel; Jung, Seung-Yong; Ding, Shi-You; Zeng, Yining; Jawdy, Sara; Sykes, Virginia R; Tuskan, Gerald A; Kalluri, Udaya C; Ragauskas, Arthur J

    2011-01-01

    Biomass is one of the most abundant potential sustainable sources for fuel and material production, however to fully realize this potential an improved understanding of lignocellulosic recalcitrance must be developed. In an effort to appreciate the underlying phenotypic, biochemical and morphological properties associated with the reduced recalcitrance observed in tension stress-induced reaction wood, we report the increased enzymatic sugar yield and corresponding chemical and ultrastructural properties of Populus tension wood. Populus tremula x alba (PTA) was grown under tension and stem segments containing three different wood types: normal wood (NW), tension wood (TW) from the elongated stem side and opposite wood (OW) from the compressed stem side were collected. A variety of analytical techniques were used to describe changes occurring as a result of the tension stress-induced formation of a gelatinous cell wall layer (G-layer). For example, gel permeation chromatography (GPC) and 13C solid-state nuclear magnetic resonance (NMR) revealed that the molecular weight and crystallinity of cellulose in TW is greater than that of cellulose acquired from NW. Whole cell ionic liquid and other solid-state NMR analysis detailed the structure of lignin and hemicellulose in the samples, detecting the presence of variations in lignin and hemicellulose sub-units, linkages and semi-quantitatively estimating the relative amounts of syringyl (S), guaiacyl (G) and p-hydroxybenzoate (PB) monolignol units. It was confirmed that TW displayed an increase in PB or H-like lignin and S to G ratio from 1.25 to 1.50 when compared to the NW sample. Scanning electron microscopy (SEM) and coherent anti-Stokes Raman scattering (CARS) were also used to evaluate the morphology and corresponding spatial distribution of the major lignocellulosic components. We found changes in a combination of cell wall properties appear to influence recalcitrance more than any single factor alone.

  8. Theoretical Mathematics

    NASA Astrophysics Data System (ADS)

    Stöltzner, Michael

    Answering to the double-faced influence of string theory on mathematical practice and rigour, the mathematical physicists Arthur Jaffe and Frank Quinn have contemplated the idea that there exists a `theoretical' mathematics (alongside `theoretical' physics) whose basic structures and results still require independent corroboration by mathematical proof. In this paper, I shall take the Jaffe-Quinn debate mainly as a problem of mathematical ontology and analyse it against the backdrop of two philosophical views that are appreciative towards informal mathematical development and conjectural results: Lakatos's methodology of proofs and refutations and John von Neumann's opportunistic reading of Hilbert's axiomatic method. The comparison of both approaches shows that mitigating Lakatos's falsificationism makes his insights about mathematical quasi-ontology more relevant to 20th century mathematics in which new structures are introduced by axiomatisation and not necessarily motivated by informal ancestors. The final section discusses the consequences of string theorists' claim to finality for the theory's mathematical make-up. I argue that ontological reductionism as advocated by particle physicists and the quest for mathematically deeper axioms do not necessarily lead to identical results.

  9. Strategic of Applying Free Chemical Usage In Purified Water System For Pharmaceutical Industry Toward CPOB (Cara Pembuatan Obat yang Baik) Indonesia To Reducing Environmental Pollution

    NASA Astrophysics Data System (ADS)

    Kartono, R.; Basuki, Y. T.

    2014-03-01

    The purpose of this paper is to examine the sets of model and literature review to prove that strategy of applying free chemical usage in purified water system for pharmaceutical industry would be help the existing and new pharmaceutical companies to comply with part of Natioanal Agency of Drug and Food Control / Badan Pengawas Obat dan Makanan (NADFC/BPOM) regulation in order to achieve "Cara Pembuatan Obat yang Baik" (CPOB) of Indonesia pharmaceutical industry. One of the main reasons is when we figured out the number of Indonesian pharmaceutical industries in 2012 are kept reducing compare to the increasing numbers of Indonesian population growth. This strategy concept also might help the industries to reducing environmental pollution, and operational cost in pharmaceutical industries, by reducing of the chemical usage for water treatment process in floculation and cougulation and chlorination for sterillization. This new model is free usage of chemicals for purified water generation system process and sterilization. The concept offering of using membrane technology- Reverse Osmosis (RO) membrane base treatment to replace traditional chemical base treatment, following enhance Electrodeionization (EDI) as final polisher for controlling conductivity, and finally Ultra Violet (UV) disinfectant technology as final guard for bacteria controls instead of chemical base system in purified water generation system.

  10. Combined microspectrophotometric and crystallographic examination of chemically-reduced and X-ray radiation-reduced forms of cytochrome ba3 oxidase from Thermus thermophilus

    PubMed Central

    Liu, Bin; Chen, Ying; Doukov, Tzanko; Soltis, S. Michael; Stout, C. David; Fee, James A.

    2009-01-01

    Three paths are described to obtain crystals of reduced (II-E4Q/I-K258R) cytochrome ba3, and the structures of these are reported at ∼2.8 to 3.0 Å resolution. Microspectrophotometry of single crystals of Thermus ba3 oxidase at 100 K was used to show that crystals of the oxidized enzyme are reduced in an intense X-ray (beam line 7-1 at the Stanford Synchrotron Radiation Laboratory, U.S.A) being nearly complete in one minute. The previously reported structures of ba3 (PDB codes 1EHK and 1XME), having a crystallographically detectable water between the CuB and Fea3 metals of the dinuclear center, actually represent the X-ray radiation-reduced enzyme. Dithionite reduced crystals or crystals formed from dithionite reduced enzyme revealed the absence of the above mentioned water and an increase in the CuB - Fea3 distance of ∼0.3 A. The new structures are discussed in terms of enzyme function. An unexpected optical absorption envelope at ∼590 nm is also reported. This spectral feature is tentatively thought to arise from a 5-coordinate, low-spin, ferrous heme-a3 that is trapped in the frozen crystals. PMID:19140675

  11. Use of formulated Trichoderma sp. Tri-1 in combination with reduced rates of chemical pesticide for control of Sclerotinia sclerotiorium on oilseed rape

    USDA-ARS?s Scientific Manuscript database

    Sustainable strategies for control of Sclerotinia sclerotiorum on oilseed rape are needed. Here we tested combinations of Trichoderma sp. Tri-1, formulated with oilseed rape seedcake and straw, with reduced application rates of the chemical pesticide Carbendazim for control of this pathogen on oils...

  12. Experimental Mathematics and Mathematical Physics

    SciTech Connect

    Bailey, David H.; Borwein, Jonathan M.; Broadhurst, David; Zudilin, Wadim

    2009-06-26

    One of the most effective techniques of experimental mathematics is to compute mathematical entities such as integrals, series or limits to high precision, then attempt to recognize the resulting numerical values. Recently these techniques have been applied with great success to problems in mathematical physics. Notable among these applications are the identification of some key multi-dimensional integrals that arise in Ising theory, quantum field theory and in magnetic spin theory.

  13. Abstraction in mathematics.

    PubMed Central

    Ferrari, Pier Luigi

    2003-01-01

    Some current interpretations of abstraction in mathematical settings are examined from different perspectives, including history and learning. It is argued that abstraction is a complex concept and that it cannot be reduced to generalization or decontextualization only. In particular, the links between abstraction processes and the emergence of new objects are shown. The role that representations have in abstraction is discussed, taking into account both the historical and the educational perspectives. As languages play a major role in mathematics, some ideas from functional linguistics are applied to explain to what extent mathematical notations are to be considered abstract. Finally, abstraction is examined from the perspective of mathematics education, to show that the teaching ideas resulting from one-dimensional interpretations of abstraction have proved utterly unsuccessful. PMID:12903658

  14. Why Mathematics?

    ERIC Educational Resources Information Center

    McClellan, Kathryn T.

    Why mathematics should be learned is discussed. Its role as an important active force in the development of our civilization, and as the most useful subject taught in our schools, next to English, is noted. The primary objective of all mathematics work is to help man study nature, and some practical achievements of this connection are noted.…

  15. Mathematics Chapter.

    ERIC Educational Resources Information Center

    Davis, Robert B.

    Suggestions are offered for more effective implementation and creativity in developing new mathematics programs. The new mathematics materials and projects have not significantly altered the educational experiences of students because of (1) difficulty in identifying distinctive features of the various projects, (2) widespread assumptions that the…

  16. Technical Mathematics.

    ERIC Educational Resources Information Center

    Flannery, Carol A.

    This manuscript provides information and problems for teaching mathematics to vocational education students. Problems reflect applications of mathematical concepts to specific technical areas. The materials are organized into six chapters. Chapter 1 covers basic arithmetic, including fractions, decimals, ratio and proportions, percentages, and…

  17. Mathematics Scrapbook

    ERIC Educational Resources Information Center

    Prochazka, Helen

    2004-01-01

    One section of this "scrapbook" section describes Pythagoras' belief in the connections between music and mathematics -- that everything in the universe was a series of harmonies and regulated by music. Another section explains why Phythagoras felt it important for women to be encouraged to learn mathematics. At least 28 women were involved in his…

  18. Technical Mathematics.

    ERIC Educational Resources Information Center

    Flannery, Carol A.

    This manuscript provides information and problems for teaching mathematics to vocational education students. Problems reflect applications of mathematical concepts to specific technical areas. The materials are organized into six chapters. Chapter 1 covers basic arithmetic, including fractions, decimals, ratio and proportions, percentages, and…

  19. Mathematics Education.

    ERIC Educational Resources Information Center

    Langbort, Carol, Ed.; Curtis, Deborah, Ed.

    2000-01-01

    The focus of this special issue is mathematics education. All articles were written by graduates of the new masters Degree program in which students earn a Master of Arts degree in Education with a concentration in Mathematics Education at San Francisco State University. Articles include: (1) "Developing Teacher-Leaders in a Masters Degree Program…

  20. Mathematical Literacy

    ERIC Educational Resources Information Center

    Martin, Hope

    2007-01-01

    "Mathematical literacy" implies that a person is able to reason, analyze, formulate, and solve problems in a real-world setting. Mathematically literate individuals are informed citizens and intelligent consumers. They have the ability to interpret and analyze the vast amount of information they are inundated with daily in newspapers, on…

  1. Peterson's Top Colleges for Science: A Guide to Leading Four-Year Programs in the Biological, Chemical, Geological, Mathematical, and Physical Sciences.

    ERIC Educational Resources Information Center

    Davis-Van Atta, David, Ed.

    This guide, published for the first time, provides prospective college students detailed information on 190 United States colleges and universities identified as having very strong track records in the sciences and mathematics. Following a description of how institutions were identified for inclusion by David Davis-Van Atta, and a discussion on…

  2. A biological/chemical process for reduced waste and energy consumption, Caprolactam production: Phase 1, Select microorganisms and demonstrate feasibility. Final report

    SciTech Connect

    St.Martin, E.J.

    1995-08-01

    A novel biological/chemical process for converting cyclohexane into caprolactam was investigated. Microorganisms in a bioreactor would be used to convert cyclohexane into caprolactone followed by chemical synthesis of caprolactam using ammonia. The proposed bioprocess would be more energy efficient and reduce byproducts and wastes that are generated by the current chemical process. We have been successful in isolating from natural soil and water samples two microorganisms that can utilize cyclohexane as a sole source of carbon and energy for growth. These microorganisms were shown to have the correct metabolic intermediates and enzymes to convert cyclohexane into cyclohexanol, cyclohexanone and caprolactone. Genetic techniques to create and select for caprolactone hydrolase negative-mutants are being developed. These blocked-mutants will be used to convert cyclohexane into caprolactone but, because of the block, be unable to metabolize the caprolactone further and excrete it as a final end product.

  3. [Process monitoring of dissolution of valsartan and hydrochlorothiazide tablets by fiber-chemical sensor assisted by mathematical separation model of linear equations].

    PubMed

    Ding, Hai-Yan; Li, Gai-Ru; Yu, Ying-Ge; Guo, Wei; Zhi, Ling; Li, Xin-Xia

    2014-04-01

    A method for on-line monitoring the dissolution of Valsartan and hydrochlorothiazide tablets assisted by mathematical separation model of linear equations was established. UV spectrums of valsartan and hydrochlorothiazide were overlapping completely at the maximum absorption wavelength respectively. According to the Beer-Lambert principle of absorbance additivity, the absorptivity of Valsartan and hydrochlorothiazide was determined at the maximum absorption wavelength, and the dissolubility of Valsartan and hydrochlorothiazide tablets was detected by fiber-optic dissolution test (FODT) assisted by the mathematical separation model of linear equations and compared with the HPLC method. Results show that two ingredients were real-time determined simultaneously in given medium. There was no significant difference for FODT compared with HPLC (p > 0.05). Due to the dissolution behavior consistency, the preparation process of different batches was stable and with good uniformity. The dissolution curves of valsartan were faster and higher than hydrochlorothiazide. The dissolutions at 30 min of Valsartan and hydrochlorothiazide were concordant with US Pharmacopoeia. It was concluded that fiber-optic dissolution test system assisted by the mathematical separation model of linear equations that can detect the dissolubility of Valsartan and hydrochlorothiazide simultaneously, and get dissolution profiles and overall data, which can directly reflect the dissolution speed at each time. It can provide the basis for establishing standards of the drug. Compared to HPLC method with one-point data, there are obvious advantages to evaluate and analyze quality of sampling drug by FODT.

  4. Chemical Chaperones Reduce ER Stress and Restore Glucose Homeostasis in a Mouse Model of Type 2 Diabetes

    NASA Astrophysics Data System (ADS)

    Özcan, Umut; Yilmaz, Erkan; Özcan, Lale; Furuhashi, Masato; Vaillancourt, Eric; Smith, Ross O.; Görgün, Cem Z.; Hotamisligil, Gökhan S.

    2006-08-01

    Endoplasmic reticulum (ER) stress is a key link between obesity, insulin resistance, and type 2 diabetes. Here, we provide evidence that this mechanistic link can be exploited for therapeutic purposes with orally active chemical chaperones. 4-Phenyl butyric acid and taurine-conjugated ursodeoxycholic acid alleviated ER stress in cells and whole animals. Treatment of obese and diabetic mice with these compounds resulted in normalization of hyperglycemia, restoration of systemic insulin sensitivity, resolution of fatty liver disease, and enhancement of insulin action in liver, muscle, and adipose tissues. Our results demonstrate that chemical chaperones enhance the adaptive capacity of the ER and act as potent antidiabetic modalities with potential application in the treatment of type 2 diabetes.

  5. Chemical chaperones reduce ionizing radiation-induced endoplasmic reticulum stress and cell death in IEC-6 cells

    SciTech Connect

    Lee, Eun Sang; Lee, Hae-June; Lee, Yoon-Jin; Jeong, Jae-Hoon; Kang, Seongman; Lim, Young-Bin

    2014-07-25

    Highlights: • UPR activation precedes caspase activation in irradiated IEC-6 cells. • Chemical ER stress inducers radiosensitize IEC-6 cells. • siRNAs that targeted ER stress responses ameliorate IR-induced cell death. • Chemical chaperons prevent cell death in irradiated IEC-6 cells. - Abstract: Radiotherapy, which is one of the most effective approaches to the treatment of various cancers, plays an important role in malignant cell eradication in the pelvic area and abdomen. However, it also generates some degree of intestinal injury. Apoptosis in the intestinal epithelium is the primary pathological factor that initiates radiation-induced intestinal injury, but the mechanism by which ionizing radiation (IR) induces apoptosis in the intestinal epithelium is not clearly understood. Recently, IR has been shown to induce endoplasmic reticulum (ER) stress, thereby activating the unfolded protein response (UPR) signaling pathway in intestinal epithelial cells. However, the consequences of the IR-induced activation of the UPR signaling pathway on radiosensitivity in intestinal epithelial cells remain to be determined. In this study, we investigated the role of ER stress responses in IR-induced intestinal epithelial cell death. We show that chemical ER stress inducers, such as tunicamycin or thapsigargin, enhanced IR-induced caspase 3 activation and DNA fragmentation in intestinal epithelial cells. Knockdown of Xbp1 or Atf6 with small interfering RNA inhibited IR-induced caspase 3 activation. Treatment with chemical chaperones prevented ER stress and subsequent apoptosis in IR-exposed intestinal epithelial cells. Our results suggest a pro-apoptotic role of ER stress in IR-exposed intestinal epithelial cells. Furthermore, inhibiting ER stress may be an effective strategy to prevent IR-induced intestinal injury.

  6. Mathematical Geology.

    ERIC Educational Resources Information Center

    McCammon, Richard B.

    1979-01-01

    The year 1978 marked a continued trend toward practical applications in mathematical geology. Developments included work in interactive computer graphics, factor analysis, the vanishing tons problem, universal kriging, and resource estimating. (BB)

  7. Mathematics Detective.

    ERIC Educational Resources Information Center

    Johnson, Jerry

    1997-01-01

    Presents 12 questions related to a given real-life situation about a man shaving and the number of hairs in his beard in order to help students see the connection between mathematics and the world around them. (ASK)

  8. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil.

    PubMed

    Cassidy, Daniel P; Srivastava, Vipul J; Dombrowski, Frank J; Lingle, James W

    2015-10-30

    Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Reduced weight decontamination formulation utilizing a solid peracid compound for neutralization of chemical and biological warfare agents

    DOEpatents

    Tucker, Mark D.

    2011-09-20

    A reduced weight decontamination formulation that utilizes a solid peracid compound (sodium borate peracetate) and a cationic surfactant (dodecyltrimethylammonium chloride) that can be packaged with all water removed. This reduces the packaged weight of the decontamination formulation by .about.80% (as compared to the "all-liquid" DF-200 formulation) and significantly lowers the logistics burden on the warfighter. Water (freshwater or saltwater) is added to the new decontamination formulation at the time of use from a local source.

  10. Dynamic Boolean Mathematics

    ERIC Educational Resources Information Center

    Bossé, Michael J.; Adu-Gyamfi, Kwaku; Chandler, Kayla; Lynch-Davis, Kathleen

    2016-01-01

    Dynamic mathematical environments allow users to reify mathematical concepts through multiple representations, transform mathematical relations and organically explore mathematical properties, investigate integrated mathematics, and develop conceptual understanding. Herein, we integrate Boolean algebra, the functionalities of a dynamic…

  11. Dynamic Boolean Mathematics

    ERIC Educational Resources Information Center

    Bossé, Michael J.; Adu-Gyamfi, Kwaku; Chandler, Kayla; Lynch-Davis, Kathleen

    2016-01-01

    Dynamic mathematical environments allow users to reify mathematical concepts through multiple representations, transform mathematical relations and organically explore mathematical properties, investigate integrated mathematics, and develop conceptual understanding. Herein, we integrate Boolean algebra, the functionalities of a dynamic…

  12. Light-Emitting Diode Phototherapy Reduces Nocifensive Behavior Induced by Thermal and Chemical Noxious Stimuli in Mice: Evidence for the Involvement of Capsaicin-Sensitive Central Afferent Fibers.

    PubMed

    Pigatto, Glauce Regina; Coelho, Igor Santos; Aquino, Rosane Schenkel; Bauermann, Liliane Freitas; Santos, Adair Roberto Soares

    2016-04-07

    Low-intensity phototherapy using light fonts, like light-emitting diode (LED), in the red to infrared spectrum is a promising alternative for the treatment of pain. However, the underlying mechanisms by which LED phototherapy reduces acute pain are not yet well understood. This study investigated the analgesic effect of multisource LED phototherapy on the acute nocifensive behavior of mice induced by thermal and chemical noxious stimuli. The involvement of central afferent C fibers sensitive to capsaicin in this effect was also investigated. Mice exposed to multisource LED (output power 234, 390, or 780 mW and power density 10.4, 17.3, and 34.6 mW/cm(2), respectively, from 10 to 30 min of stimulation with a wavelength of 890 nm) showed rapid and significant reductions in formalin- and acetic acid-induced nocifensive behavior. This effect gradually reduced but remained significant for up to 7 h after LED treatment in the last model used. Moreover, LED (390 mW, 17.3 mW/cm(2)/20 min) irradiation also reduced nocifensive behavior in mice due to chemical [endogenous (i.e., glutamate, prostaglandins, and bradykinin) or exogenous (i.e., formalin, acetic acid, TRPs and ASIC agonist, and protein kinase A and C activators)] and thermal (hot plate test) stimuli. Finally, ablating central afferent C fibers abolished LED analgesia. These experimental results indicate that LED phototherapy reduces the acute painful behavior of animals caused by chemical and thermal stimuli and that LED analgesia depends on the integrity of central afferent C fibers sensitive to capsaicin. These findings provide new information regarding the underlying mechanism by which LED phototherapy reduces acute pain. Thus, LED phototherapy may be an important tool for the management of acute pain.

  13. Fully adiabatic 31P 2D-CSI with reduced chemical shift displacement error at 7 T--GOIA-1D-ISIS/2D-CSI.

    PubMed

    Chmelík, M; Kukurová, I Just; Gruber, S; Krššák, M; Valkovič, L; Trattnig, S; Bogner, W

    2013-05-01

    A fully adiabatic phosphorus (31P) two-dimensional (2D) chemical shift spectroscopic imaging sequence with reduced chemical shift displacement error for 7 T, based on 1D-image-selected in vivo spectroscopy, combined with 2D-chemical shift spectroscopic imaging selection, was developed. Slice-selective excitation was achieved by a spatially selective broadband GOIA-W(16,4) inversion pulse with an interleaved subtraction scheme before nonselective adiabatic excitation, and followed by 2D phase encoding. The use of GOIA-W(16,4) pulses (bandwidth 4.3-21.6 kHz for 10-50 mm slices) reduced the chemical shift displacement error in the slice direction ∼1.5-7.7 fold, compared to conventional 2D-chemical shift spectroscopic imaging with Sinc3 selective pulses (2.8 kHz). This reduction was experimentally demonstrated with measurements of an MR spectroscopy localization phantom and with experimental evaluation of pulse profiles. In vivo experiments in clinically acceptable measurement times were demonstrated in the calf muscle (nominal voxel volume, 5.65 ml in 6 min 53 s), brain (10 ml, 6 min 32 s), and liver (8.33 ml, 8 min 14 s) of healthy volunteers at 7 T. High reproducibility was found in the calf muscle at 7 T. In combination with adiabatic excitation, this sequence is insensitive to the B1 inhomogeneities associated with surface coils. This sequence, which is termed GOIA-1D-ISIS/2D-CSI (goISICS), has the potential to be applied in both clinical research and in the clinical routine. Copyright © 2012 Wiley Periodicals, Inc.

  14. Mathematical wit and mathematical cognition.

    PubMed

    Aberdein, Andrew

    2013-04-01

    The published works of scientists often conceal the cognitive processes that led to their results. Scholars of mathematical practice must therefore seek out less obvious sources. This article analyzes a widely circulated mathematical joke, comprising a list of spurious proof types. An account is proposed in terms of argumentation schemes: stereotypical patterns of reasoning, which may be accompanied by critical questions itemizing possible lines of defeat. It is argued that humor is associated with risky forms of inference, which are essential to creative mathematics. The components of the joke are explicated by argumentation schemes devised for application to topic-neutral reasoning. These in turn are classified under seven headings: retroduction, citation, intuition, meta-argument, closure, generalization, and definition. Finally, the wider significance of this account for the cognitive science of mathematics is discussed.

  15. Mathematical modelling of physical and chemical processes of coal combustion in chamber furnaces of boiler aggregates based on the package of applied programs FIRE 3D

    NASA Astrophysics Data System (ADS)

    Gil, A. V.; Starchenko, A. V.

    2012-09-01

    The furnace processes of the combustion of poly-fraction high-ashes Ekibastuz coal in the furnace chamber of the boiler aggregate PK-39 and of the combustion of highly humid brown Berezov's coal in the furnace of the BKZ-210-140 boiler are investigated by mathematical modeling using the package of applied programs FIRE 3D [1-3]. Results of the numerical modeling of the processes of aerodynamics, heat exchange, and combustion in the furnace volume and their comparison with the results of nature tests are presented.

  16. Chemical recovery of surface waters across the northeastern united states from reduced inputs of acidic deposition: 1984-2001.

    PubMed

    Warby, Richard A F; Johnson, Chris E; Driscoll, Charles T

    2005-09-01

    Changes in lake water chemistry between 1984 and 2001 at 130 stratified random sites across the northeastern United States were studied to evaluate the population-level effects of decreases in acidic deposition. Surface-water S04(2-) concentrations decreased across the region at a median rate of -1.53 microequiv L(-1) year(-1). Calcium concentrations also decreased, with a median rate of -1.73 microequiv L(-1) year(-1). This decrease in Ca2+ retarded the recovery of surface water acid neutralizing capacity (Gran ANC), which increased at a median rate of 0.66 microequiv L(-1) year(-1). There were small increases in pH in all subregions except central New England and Maine, where the changes were not statistically significant. Median NO3- trends were not significant except in the Adirondacks, where NO3- concentrations increased at a rate of 0.53 microequiv L(-1) year(-1). A regionwide decrease in the concentration of total Al, especially in ponds with low ANC values (ANC < 25 microequiv L(-1)), was observed in the Adirondack subregion. These changes in Al were consistent with the general pattern of increasing pH and ANC. Despite the general pattern of chemical recovery, many ponds remain chronically acidic or are susceptible to episodic acidification. The continued chemical and biological recovery at sites in the northeastern United States will depend on further controls on S and N emissions.

  17. Chemical chaperones reduce ionizing radiation-induced endoplasmic reticulum stress and cell death in IEC-6 cells.

    PubMed

    Lee, Eun Sang; Lee, Hae-June; Lee, Yoon-Jin; Jeong, Jae-Hoon; Kang, Seongman; Lim, Young-Bin

    2014-07-25

    Radiotherapy, which is one of the most effective approaches to the treatment of various cancers, plays an important role in malignant cell eradication in the pelvic area and abdomen. However, it also generates some degree of intestinal injury. Apoptosis in the intestinal epithelium is the primary pathological factor that initiates radiation-induced intestinal injury, but the mechanism by which ionizing radiation (IR) induces apoptosis in the intestinal epithelium is not clearly understood. Recently, IR has been shown to induce endoplasmic reticulum (ER) stress, thereby activating the unfolded protein response (UPR) signaling pathway in intestinal epithelial cells. However, the consequences of the IR-induced activation of the UPR signaling pathway on radiosensitivity in intestinal epithelial cells remain to be determined. In this study, we investigated the role of ER stress responses in IR-induced intestinal epithelial cell death. We show that chemical ER stress inducers, such as tunicamycin or thapsigargin, enhanced IR-induced caspase 3 activation and DNA fragmentation in intestinal epithelial cells. Knockdown of Xbp1 or Atf6 with small interfering RNA inhibited IR-induced caspase 3 activation. Treatment with chemical chaperones prevented ER stress and subsequent apoptosis in IR-exposed intestinal epithelial cells. Our results suggest a pro-apoptotic role of ER stress in IR-exposed intestinal epithelial cells. Furthermore, inhibiting ER stress may be an effective strategy to prevent IR-induced intestinal injury.

  18. Chemical chaperones reduce ER stress and adipose tissue inflammation in high fat diet-induced mouse model of obesity

    PubMed Central

    Chen, Yaqin; Wu, Zhihong; Zhao, Shuiping; Xiang, Rong

    2016-01-01

    Obesity, which is characteristic by chronic inflammation, is defined as abnormal or excessive fat accumulation in adipose tissues. Endoplasmic reticulum (ER) stress is increased in adipose tissue of obese state and is known to be strongly associated with chronic inflammation. The aim of this study was to investigate the effect of ER stress on adipokine secretion in obese mice and explore the potential mechanisms. In this study, we found high-fat diet induced-obesity contributed to strengthened ER stress and triggered chronic inflammation in adipose tissue. Chemical chaperones, 4-PBA and TUDCA, modified metabolic disorders and decreased the levels of inflammatory cytokines in obese mice fed a high-fat diet. The alleviation of ER stress is in accordance with the decrease of free cholesterol in adipose tissue. Furthermore chemical chaperones suppress NF-κB activity in adipose tissue of obese mice in vivo. In vitro studies showed IKK/NF-κB may be involved in the signal transduction of adipokine secretion dysfunction induced by ER stress. The present study revealed the possibility that inhibition of ER stress may be a novel drug target for metabolic abnormalities associated with obesity. Further studies are now needed to characterize the initial incentive of sustained ER stress in obese. PMID:27271106

  19. Mathematical Perspectives

    SciTech Connect

    Glimm, J.

    2009-10-14

    Progress for the past decade or so has been extraordinary. The solution of Fermat's Last Theorem [11] and of the Poincare Conjecture [1] have resolved two of the most outstanding challenges to mathematics. For both cases, deep and advanced theories and whole subfields of mathematics came into play and were developed further as part of the solutions. And still the future is wide open. Six of the original seven problems from the Clay Foundation challenge remain open, the 23 DARPA challenge problems are open. Entire new branches of mathematics have been developed, including financial mathematics and the connection between geometry and string theory, proposed to solve the problems of quantized gravity. New solutions of the Einstein equations, inspired by shock wave theory, suggest a cosmology model which fits accelerating expansion of the universe possibly eliminating assumptions of 'dark matter'. Intellectual challenges and opportunities for mathematics are greater than ever. The role of mathematics in society continues to grow; with this growth comes new opportunities and some growing pains; each will be analyzed here. We see a broadening of the intellectual and professional opportunities and responsibilities for mathematicians. These trends are also occuring across all of science. The response can be at the level of the professional societies, which can work to deepen their interactions, not only within the mathematical sciences, but also with other scientific societies. At a deeper level, the choices to be made will come from individual mathematicians. Here, of course, the individual choices will be varied, and we argue for respect and support for this diversity of responses. In such a manner, we hope to preserve the best of the present while welcoming the best of the new.

  20. Mathematical vistas

    SciTech Connect

    Malkevitch, J. ); McCarthy, D. )

    1990-01-01

    The papers in this volume represent talks given at the monthly meetings of the Mathematics Section of the New York Academy of Sciences. They reflect the operating philosophy of the Section in its efforts to make a meaningful contribution to the mathematical life of a community that is exceedingly rich in cultural resources and intellectual opportunities. Each week during the academic year a dazzling abundance of mathematical seminars and colloquia is available in the New York metropolitan area. Most of these offer highly technical treatments intended for specialists. At the New York Academy we try to provide a forum of a different sort, where interesting ideas are presented in a congenial atmosphere to a broad mathematical audience. Many of the Section talks contain substantial specialized material, but we ask our speakers to include a strong expository component aimed at working mathematicians presumed to have no expert knowledge of the topic at hand. We urge speakers to try to provide the motivating interest they themselves would like to find in an introduction to a field other than their own. The same advice has been given to the authors of the present papers, with the goal of producing a collection that will be both accessible and stimulating to mathematical minds at large. We have tried to provide variety in the mathematical vistas offered; both pure and applied mathematics are well represented. Since the papers are presented alphabetically by author, some guidance seems appropriate as to what sorts of topics are treated, and where. There are three papers in analysis: those by Engber, Narici and Beckenstein, and Todd. Engber's deals with complex analysis on compact Riemann surfaces; Narici and Beckenstein provide an introduction to analysis on non-Archimendean fields; Todd surveys an area of contemporary functional analysis.

  1. Long-term manure incorporation with chemical fertilizers reduced environmental nitrogen loss in rain-fed cropping systems

    USDA-ARS?s Scientific Manuscript database

    Improving soil fertility/productivity and reducing environmental impact of nitrogen (N) fertilization in intensive farming systems are essential for sustainable agriculture and food security around the world. The objective of this study was to determine the long-term effects of various fertilization...

  2. A screen of chemical modifications identifies position-specific modification by UNA to most potently reduce siRNA off-target effects

    PubMed Central

    Bramsen, Jesper B.; Pakula, Malgorzata M.; Hansen, Thomas B.; Bus, Claus; Langkjær, Niels; Odadzic, Dalibor; Smicius, Romualdas; Wengel, Suzy L.; Chattopadhyaya, Jyoti; Engels, Joachim W.; Herdewijn, Piet; Wengel, Jesper; Kjems, Jørgen

    2010-01-01

    Small interfering RNAs (siRNAs) are now established as the preferred tool to inhibit gene function in mammalian cells yet trigger unintended gene silencing due to their inherent miRNA-like behavior. Such off-target effects are primarily mediated by the sequence-specific interaction between the siRNA seed regions (position 2–8 of either siRNA strand counting from the 5′-end) and complementary sequences in the 3′UTR of (off-) targets. It was previously shown that chemical modification of siRNAs can reduce off-targeting but only very few modifications have been tested leaving more to be identified. Here we developed a luciferase reporter-based assay suitable to monitor siRNA off-targeting in a high throughput manner using stable cell lines. We investigated the impact of chemically modifying single nucleotide positions within the siRNA seed on siRNA function and off-targeting using 10 different types of chemical modifications, three different target sequences and three siRNA concentrations. We found several differently modified siRNAs to exercise reduced off-targeting yet incorporation of the strongly destabilizing unlocked nucleic acid (UNA) modification into position 7 of the siRNA most potently reduced off-targeting for all tested sequences. Notably, such position-specific destabilization of siRNA–target interactions did not significantly reduce siRNA potency and is therefore well suited for future siRNA designs especially for applications in vivo where siRNA concentrations, expectedly, will be low. PMID:20453030

  3. Chemical recovery of surface waters across the Northeastern United States from reduced inputs of acidic deposition: 1984-2001

    SciTech Connect

    Richard A.F. Warby; Chris E. Johnson; Charles T. Driscoll

    2005-09-01

    Changes in lake water chemistry between 1984 and 2001 at 130 stratified random sites across the northeastern United States were studied to evaluate the population-level effects of decreases in acidic deposition. Surface-water SO{sub 4}{sup 2-} concentrations decreased across the region at a median rate of -1.53 {mu}equiv L{sup -1} year{sup -1}. Calcium concentrations also decreased, with a median rate of -1.73 {mu}equiv L{sup -1} year{sup -1}. This decrease in Ca{sub 2+} retarded the recovery of surface water acid neutralizing capacity (Gran ANC), which increased at a median rate of 0.66 {mu}equiv L{sup -1} year{sup -1}. There were small increases in pH in all subregions except central New England and Maine, where the changes were not statistically significant. Median NO{sub 3}{sup -} trends were not significant except in the Adirondacks, where NO{sub 3}{sup -} concentrations increased at a rate of 0.53 equiv L{sup -1} year{sup -1}. A regionwide decrease in the concentration of total Al, especially in ponds with low ANC values (ANC {lt} 25 {mu}equiv L{sup -1}), was observed in the Adirondack subregion. These changes in Al were consistent with the general pattern of increasing pH and ANC. Despite the general pattern of chemical recovery, many ponds remain chronically acidic or are susceptible to episodic acidification. The continued chemical and biological recovery at sites in the northeastern United States will depend on further controls on S and N emissions. 27 refs., 4 figs., 3 tabs.

  4. Computer program determines chemical composition of physical system at equilibrium

    NASA Technical Reports Server (NTRS)

    Kwong, S. S.

    1966-01-01

    FORTRAN 4 digital computer program calculates equilibrium composition of complex, multiphase chemical systems. This is a free energy minimization method with solution of the problem reduced to mathematical operations, without concern for the chemistry involved. Also certain thermodynamic properties are determined as byproducts of the main calculations.

  5. Use of chemical sanitizers to reduce microbial populations and maintain quality of whole and fresh-cut cantaloupe.

    PubMed

    Fan, Xuetong; Annous, Bassam A; Keskinen, Lindsey A; Mattheis, James P

    2009-12-01

    Whole cantaloupes either not inoculated or inoculated with Salmonella Poona were submerged in water, 180 ppm of chlorine, acidified calcium sulfate (ACS: 1.2% Safe(2)O-ACS50), 1,000 ppm of acidified sodium chlorite (ASC), 80 ppm of peroxyacetic acid (PAA), and a combination of ACS and PAA for 10 min. Although only ASC and the combination of ACS and PAA significantly reduced the aerobic plate count of samples taken from the surface of whole cantaloupe (compared with samples taken from cantaloupe submerged in water only), all treatments reduced yeast and mold counts on the whole cantaloupe. However, none of the treatments of whole cantaloupes consistently reduced yeast and mold counts for the samples of fresh-cut cantaloupes. The aerobic plate counts for fresh-cut cantaloupe were reduced by 1 to 2 log CFU/g by sanitization of whole fruit with ASC, ACS, and the combination of ACS and PAA. The low bacterial population on the fresh-cut fruit was maintained during 14 days of storage at 4 degrees C. All treatments had a limited effect on the population of Salmonella, achieving no more than a 1.5-log reduction of the pathogen inoculated on the surface of the whole cantaloupes. Salmonella was nondetectable via direct plating (with a detection limit of 0.4 log CFU/g) in fresh-cut cantaloupes prepared from whole cantaloupes treated with any of the sanitizers. However, after enrichment, Salmonella often was detectable. Color, texture, soluble solids, pH, ascorbic acid, and drip loss of cut cantaloupes were not consistently affected by any of the whole-fruit treatments. Overall, treatments of whole cantaloupe with ASC, ACS, and the combination of ACS and PAA at the concentrations tested permitted a significant reduction in Salmonella and native microflora of whole and cut fruit; however, Salmonella still could be found in cut cantaloupes from all treatments.

  6. Quotable Quotes in Mathematics

    ERIC Educational Resources Information Center

    Lo, Bruce W. N.

    1983-01-01

    As a way to dispel negative feelings toward mathematics, a variety of quotations are given. They are categorized by: what mathematics is, mathematicians, mathematics and other disciplines, different areas of mathematics, mathematics and humor, applications of mathematics, and pure versus applied mathematics. (MNS)

  7. Long-term operation of microbial electrosynthesis cell reducing CO2 to multi-carbon chemicals with a mixed culture avoiding methanogenesis.

    PubMed

    Bajracharya, Suman; Yuliasni, Rustiana; Vanbroekhoven, Karolien; Buisman, Cees J N; Strik, David P B T B; Pant, Deepak

    2017-02-01

    In microbial electrosynthesis (MES), CO2 can be reduced preferably to multi-carbon chemicals by a biocathode-based process which uses electrochemically active bacteria as catalysts. A mixed anaerobic consortium from biological origin typically produces methane from CO2 reduction which circumvents production of multi-carbon compounds. This study aimed to develop a stable and robust CO2 reducing biocathode from a mixed culture inoculum avoiding the methane generation. An effective approach was demonstrated based on (i) an enrichment procedure involving inoculum pre-treatment and several culture transfers in H2:CO2 media, (ii) a transfer from heterotrophic to autotrophic growth and (iii) a sequential batch operation. Biomass growth and gradual acclimation to CO2 electro-reduction accomplished a maximum acetate production rate of 400mgLcatholyte(-1)d(-1) at -1V (vs. Ag/AgCl). Methane was never detected in more than 300days of operation. Accumulation of acetate up to 7-10gL(-1) was repeatedly attained by supplying (80:20) CO2:N2 mixture at -0.9 to -1V (vs. Ag/AgCl). In addition, ethanol and butyrate were also produced from CO2 reduction. Thus, a robust CO2 reducing biocathode can be developed from a mixed culture avoiding methane generation by adopting the specific culture enrichment and operation procedures without the direct addition of chemical inhibitor.

  8. Physico-chemical properties based differential toxicity of graphene oxide/reduced graphene oxide in human lung cells mediated through oxidative stress

    NASA Astrophysics Data System (ADS)

    Mittal, Sandeep; Kumar, Veeresh; Dhiman, Nitesh; Chauhan, Lalit Kumar Singh; Pasricha, Renu; Pandey, Alok Kumar

    2016-12-01

    Goraphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs). But, the possible association of their properties with underlying in vitro effects have not fully examined. Here, we assessed the comparative interaction of three GD - graphene oxide (GO), thermally reduced GO (TRGO) and chemically reduced GO (CRGO), which significantly differ in their lateral size and functional groups density, with phenotypically different human lung cells; bronchial epithelial cells (BEAS-2B) and alveolar epithelial cells (A549). The cellular studies demonstrate that GD significantly ineternalize and induce oxidative stress mediated cytotoxicity in both cells. The toxicity intensity was in line with the reduced lateral size and increased functional groups revealed more toxicity potential of TRGO and GO respectively. Further, A549 cells showed more susceptibility than BEAS-2B which reflected cell type dependent differential cellular response. Molecular studies revealed that GD induced differential cell death mechanism which was efficiently prevented by their respective inhibitors. This is prior study to the best of our knowledge involving TRGO for its safety evaluation which provided invaluable information and new opportunities for GD based biomedical applications.

  9. Application of Glomus sp. and Pseudomonas diminuta Reduce the Use of Chemical Fertilizers in Production of Potato Grown on Different Soil Types

    NASA Astrophysics Data System (ADS)

    Nurbaity, A.; Sofyan, E. T.; Hamdani, J. S.

    2016-08-01

    The use of high chemical fertilizer rates in potato production has been applied on the farm in Indonesia. Application of biofertilizer consists of arbuscular mycorrhizal fungi has been tested to reduce the use of NPK rates in production of potato and to determine whether different soil types will have different response to this biofertilizer. A greenhouse experiment was conducted using mixtures of spores of Glomus sp. and inoculant of mycorrhizal helper bacteria Pseudomonas diminuta, applied at different rates of NPK fertilizer (0, 25, 50, 75 and 100% of recommended rates) and different soil types (Andisols and Inceptisols). Results of experiment showed that application of Glomus sp. and P. diminuta reduced the use of NPK up to 50%, where the growth (plant height and tuber number), N,P,K uptake and tuber yields of potato had similar effect to the highest recommendation rate of NPK fertilizer. Inceptisols in general had better response to the biofertiliser compared to Andisols. Findings from this experiment confirmed the evidences that biofertilizer could reduce the use of chemical fertilizer, and the widely distributed soil in Indonesia such as Inceptisols, is potential to be used as a medium for potato production.

  10. Physico-chemical properties based differential toxicity of graphene oxide/reduced graphene oxide in human lung cells mediated through oxidative stress

    PubMed Central

    Mittal, Sandeep; Kumar, Veeresh; Dhiman, Nitesh; Chauhan, Lalit Kumar Singh; Pasricha, Renu; Pandey, Alok Kumar

    2016-01-01

    Goraphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs). But, the possible association of their properties with underlying in vitro effects have not fully examined. Here, we assessed the comparative interaction of three GD - graphene oxide (GO), thermally reduced GO (TRGO) and chemically reduced GO (CRGO), which significantly differ in their lateral size and functional groups density, with phenotypically different human lung cells; bronchial epithelial cells (BEAS-2B) and alveolar epithelial cells (A549). The cellular studies demonstrate that GD significantly ineternalize and induce oxidative stress mediated cytotoxicity in both cells. The toxicity intensity was in line with the reduced lateral size and increased functional groups revealed more toxicity potential of TRGO and GO respectively. Further, A549 cells showed more susceptibility than BEAS-2B which reflected cell type dependent differential cellular response. Molecular studies revealed that GD induced differential cell death mechanism which was efficiently prevented by their respective inhibitors. This is prior study to the best of our knowledge involving TRGO for its safety evaluation which provided invaluable information and new opportunities for GD based biomedical applications. PMID:28000740

  11. Chemical Modification with High Molecular Weight Polyethylene Glycol Reduces Transduction of Hepatocytes and Increases Efficacy of Intravenously Delivered Oncolytic Adenovirus

    PubMed Central

    Doronin, Konstantin; Shashkova, Elena V.; May, Shannon M.; Hofherr, Sean E.

    2009-01-01

    Abstract Oncolytic adenoviruses are anticancer agents that replicate within tumors and spread to uninfected tumor cells, amplifying the anticancer effect of initial transduction. We tested whether coating the viral particle with polyethylene glycol (PEG) could reduce transduction of hepatocytes and hepatotoxicity after systemic (intravenous) administration of oncolytic adenovirus serotype 5 (Ad5). Conjugating Ad5 with high molecular weight 20-kDa PEG but not with 5-kDa PEG reduced hepatocyte transduction and hepatotoxicity after intravenous injection. PEGylation with 20-kDa PEG was as efficient at detargeting adenovirus from Kupffer cells and hepatocytes as virus predosing and warfarin. Bioluminescence imaging of virus distribution in two xenograft tumor models in nude mice demonstrated that PEGylation with 20-kDa PEG reduced liver infection 19- to 90-fold. Tumor transduction levels were similar for vectors PEGylated with 20-kDa PEG and unPEGylated vectors. Anticancer efficacy after a single intravenous injection was retained at the level of unmodified vector in large established prostate carcinoma xenografts, resulting in complete elimination of tumors in all animals and long-term tumor-free survival. Anticancer efficacy after a single intravenous injection was increased in large established hepatocellular carcinoma xenografts, resulting in significant prolongation of survival as compared with unmodified vector. The increase in efficacy was comparable to that obtained with predosing and warfarin pretreatment, significantly extending the median of survival. Shielding adenovirus with 20-kDa PEG may be a useful approach to improve the therapeutic window of oncolytic adenovirus after systemic delivery to primary and metastatic tumor sites. PMID:19469693

  12. Chemical rules on the assessment of antioxidant potential in food and food additives aimed at reducing oxidative stress and neurodegeneration.

    PubMed

    Franco, Rafael; Martínez-Pinilla, Eva

    2017-11-15

    Antioxidants (aOXs) enlarge the useful life of products consumed by humans. Life requires oxidation of glucose/fatty acids and, therefore, "antioxidant" becomes an oxymoron when trying to define benefits in organisms living in an oxygen-rich atmosphere. According to basic physico-chemical principles, the in vivo aOX potential of food supplements is negligible when compared with the main aOX molecules in the animal Kingdom: glucose and fatty acids. Thus, the aOX assumption to improve life-quality is misleading as oxidative stress and exacerbation occur when oxidant foods (e.g. fava beans) are consumed. Evolution produced potent detoxification mechanisms to handle these situations. When age/genetic/environmental factors negatively impact on detoxification mechanisms, nutrition helps on providing metabolites/precursors needed for boosting innate resources. Ambiguous techniques that attempt to measure in vivo aOX power, should give way to measuring the level of supplements and their metabolites in body fluids/tissues, and to measure the efficacy on antioxidant boosting REDOX pathways. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Comparative evaluation of chemical and enzymatic saccharification of mixotrophically grown de-oiled microalgal biomass for reducing sugar production.

    PubMed

    Pancha, Imran; Chokshi, Kaumeel; Maurya, Rahulkumar; Bhattacharya, Sourish; Bachani, Pooja; Mishra, Sandhya

    2016-03-01

    For the commercialization of microalgal based biofuels, utilization of de-oiled carbohydrate rich biomass is important. In the present study, chemo-enzymatic hydrolysis of mixotrophically grown Scenedesmus sp. CCNM 1077 de-oiled biomass is evaluated. Among the chemical hydrolysis, use of 0.5M HCl for 45 min at 121°C resulted in highest saccharification yield of 37.87% w/w of de-oiled biomass. However, enzymatic hydrolysis using Viscozyme L at loading rate of 20 FBGU/g of de-oiled biomass, pH 5.5 and temperature 45°C for 72 h resulted in saccharification yield of 43.44% w/w of de-oiled biomass. Further, 78% ethanol production efficiency was achieved with enzymatically hydrolyzed de-oiled biomass using yeast Saccharomyces cerevisiae ATCC 6793. These findings of the present study show application of mixotrophically grown de-oiled biomass of Scenedesmus sp. CCNM 1077 as promising feedstock for bioethanol production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Treatment of textile industry effluents using orange waste: a proposal to reduce color and chemical oxygen demand.

    PubMed

    de Farias Silva, Carlos Eduardo; da Silva Gonçalves, Andreza Heloiza; de Souza Abud, Ana Karla

    Various agricultural residues have been tested as biosorbents due to their low cost, high surface area, and favorable surface chemistry. In this work, a sweet orange albedo was tested as a biosorbent for treatment of real textile effluents. The orange albedo powder was prepared by drying the residue at 50 °C and milling to 30 mesh, and then used for dye adsorption from a alkaline (pH = 10.71) effluent. The adsorption process was studied in batch experiments at 30 °C by measuring color removal and chemical oxygen demand (COD). The color removal was found not to be significantly altered when the effluent was used in its raw state, while COD increased probably due to albedo degradation. For the effluent diluted to 60% (Veffluent VH2O(-1)), color and COD removal percentages of approximately 89% were obtained. It was found that pH played a very significant role on the adsorption process, as the treated albedo displayed a relative pHPZC* of 4.61, and the highest dye removal efficiencies were reached at pH lower than 2. The COD was strongly influenced by the effluent dilution. The effectiveness in eliminating color and COD shows that orange albedo can be potentially used as a biosorbent to treat textile wastewater.

  15. One-pot wet-chemical co-reduction synthesis of bimetallic gold-platinum nanochains supported on reduced graphene oxide with enhanced electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chen, De-Jun; Zhang, Qian-Li; Feng, Jin-Xia; Ju, Ke-Jian; Wang, Ai-Jun; Wei, Jie; Feng, Jiu-Ju

    2015-08-01

    In this work, a simple, rapid and facile one-pot wet-chemical co-reduction method is developed for synthesis of bimetallic Au-Pt alloyed nanochains supported on reduced graphene oxide (Au-Pt NCs/RGO), in which caffeine is acted as a capping agent and a structure-directing agent, while no any seed, template, surfactant or polymer involved. The as-prepared nanocomposites display enlarged electrochemical active surface area, significantly enhanced catalytic activity and better stability for methanol and ethylene glycol oxidation, compared with commercial Pt-C (Pt 50 wt%), PtRu-C (Pt 30 wt% and Ru 15 wt%) and Pt black.

  16. Underground Mathematics

    ERIC Educational Resources Information Center

    Hadlock, Charles R

    2013-01-01

    The movement of groundwater in underground aquifers is an ideal physical example of many important themes in mathematical modeling, ranging from general principles (like Occam's Razor) to specific techniques (such as geometry, linear equations, and the calculus). This article gives a self-contained introduction to groundwater modeling with…

  17. Outdoor Mathematics

    ERIC Educational Resources Information Center

    Kennard, Jackie

    2007-01-01

    One of the most interesting developments in teaching has been the growing importance of the outdoor environment. Whether it be playground, garden or field, the outdoors offers a range of challenging experiences, especially in the delivery of early mathematics. Oral feedback to parents, together with photographic displays, can show them that…

  18. Underground Mathematics

    ERIC Educational Resources Information Center

    Hadlock, Charles R

    2013-01-01

    The movement of groundwater in underground aquifers is an ideal physical example of many important themes in mathematical modeling, ranging from general principles (like Occam's Razor) to specific techniques (such as geometry, linear equations, and the calculus). This article gives a self-contained introduction to groundwater modeling with…

  19. Outdoor Mathematics

    ERIC Educational Resources Information Center

    Kennard, Jackie

    2007-01-01

    One of the most interesting developments in teaching has been the growing importance of the outdoor environment. Whether it be playground, garden or field, the outdoors offers a range of challenging experiences, especially in the delivery of early mathematics. Oral feedback to parents, together with photographic displays, can show them that…

  20. Mathematical Visualization

    ERIC Educational Resources Information Center

    Rogness, Jonathan

    2011-01-01

    Advances in computer graphics have provided mathematicians with the ability to create stunning visualizations, both to gain insight and to help demonstrate the beauty of mathematics to others. As educators these tools can be particularly important as we search for ways to work with students raised with constant visual stimulation, from video games…

  1. Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification

    NASA Astrophysics Data System (ADS)

    Hartmann, Jens; West, A. Joshua; Renforth, Phil; KöHler, Peter; de La Rocha, Christina L.; Wolf-Gladrow, Dieter A.; Dürr, Hans H.; Scheffran, Jürgen

    2013-04-01

    weathering is an integral part of both the rock and carbon cycles and is being affected by changes in land use, particularly as a result of agricultural practices such as tilling, mineral fertilization, or liming to adjust soil pH. These human activities have already altered the terrestrial chemical cycles and land-ocean flux of major elements, although the extent remains difficult to quantify. When deployed on a grand scale, Enhanced Weathering (a form of mineral fertilization), the application of finely ground minerals over the land surface, could be used to remove CO2 from the atmosphere. The release of cations during the dissolution of such silicate minerals would convert dissolved CO2 to bicarbonate, increasing the alkalinity and pH of natural waters. Some products of mineral dissolution would precipitate in soils or be taken up by ecosystems, but a significant portion would be transported to the coastal zone and the open ocean, where the increase in alkalinity would partially counteract "ocean acidification" associated with the current marked increase in atmospheric CO2. Other elements released during this mineral dissolution, like Si, P, or K, could stimulate biological productivity, further helping to remove CO2 from the atmosphere. On land, the terrestrial carbon pool would likely increase in response to Enhanced Weathering in areas where ecosystem growth rates are currently limited by one of the nutrients that would be released during mineral dissolution. In the ocean, the biological carbon pumps (which export organic matter and CaCO3 to the deep ocean) may be altered by the resulting influx of nutrients and alkalinity to the ocean. This review merges current interdisciplinary knowledge about Enhanced Weathering, the processes involved, and the applicability as well as some of the consequences and risks of applying the method.

  2. Evolution of Chemical Diversity in a Group of Non-Reduced Polyketide Gene Clusters: Using Phylogenetics to Inform the Search for Novel Fungal Natural Products

    PubMed Central

    Throckmorton, Kurt; Wiemann, Philipp; Keller, Nancy P.

    2015-01-01

    Fungal polyketides are a diverse class of natural products, or secondary metabolites (SMs), with a wide range of bioactivities often associated with toxicity. Here, we focus on a group of non-reducing polyketide synthases (NR-PKSs) in the fungal phylum Ascomycota that lack a thioesterase domain for product release, group V. Although widespread in ascomycete taxa, this group of NR-PKSs is notably absent in the mycotoxigenic genus Fusarium and, surprisingly, found in genera not known for their secondary metabolite production (e.g., the mycorrhizal genus Oidiodendron, the powdery mildew genus Blumeria, and the causative agent of white-nose syndrome in bats, Pseudogymnoascus destructans). This group of NR-PKSs, in association with the other enzymes encoded by their gene clusters, produces a variety of different chemical classes including naphthacenediones, anthraquinones, benzophenones, grisandienes, and diphenyl ethers. We discuss the modification of and transitions between these chemical classes, the requisite enzymes, and the evolution of the SM gene clusters that encode them. Integrating this information, we predict the likely products of related but uncharacterized SM clusters, and we speculate upon the utility of these classes of SMs as virulence factors or chemical defenses to various plant, animal, and insect pathogens, as well as mutualistic fungi. PMID:26378577

  3. Effect of fluorine plasma treatment with chemically reduced graphene oxide thin films as hole transport layer in organic solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Youn-Yeol; Kang, Byung Hyun; Lee, Yang Doo; Lee, Sang Bin; Ju, Byeong-Kwon

    2013-12-01

    The inorganic materials such as V2O5, MoO3 and WO3 were investigated to replace PEDOT:PSS as hole transport layer (HTL) in organic electronic devices such as organic solar cells (OSCs) and organic lighting emission diodes. However, these methods require vacuum techniques that are long time process and complex. Here, we report about plasma treatment with SF6 and CF4 using reactive ion etching on reduced graphene oxide (rGO) thin films that are obtained using an eco-friendly method with vitamin C. The plasma treated rGO thin films have dipoles since they consist of covalent bonds with fluorine on the surface of rGO. This means it is possible to increase the electrostatic potential energy than bare rGO. Increased potential energy on the surface of rGO films is worth applying organic electronic devices as HTL such as OSCs. Consequently, the power conversion efficiency of OSCs increased more than the rGO films without plasma treatment.

  4. Mathematics Curriculum Guide. Mathematics IV.

    ERIC Educational Resources Information Center

    Gary City Public School System, IN.

    GRADES OR AGES: Grade 12. SUBJECT MATTER: Mathematics. ORGANIZATION AND PHYSICAL APPEARANCE: The subject matter is presented in four columns: major areas, significant outcomes, observations and suggestions, and films and references. The topics include: sets-relations-functions, circular functions, graphs of circular functions, inverses of circular…

  5. A Facile Chemical Reduction of Graphene-Oxide Using p-Toluene Sulfonic Acid and Fabrication of Reduced Graphene-Oxide Film.

    PubMed

    Vengatesan, M R; Shen, Tian-Zi; Alagar, M; Song, Jang-Kun

    2016-01-01

    We report a cost effective and easy chemical reduction method for exfoliated individual graphene oxide (GO) and GO paper using p-toluene sulfonic acid (PTSA) under mild conditions. Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), thermo gravimetric analysis (TGA) and transmission electron microscopy (TEM) analysis were performed to investigate the quality of GO reduction. Data resulting from the spectral analysis suggest that the reduction method using PTSA is an efficient method to remove oxygen functionalities in the GO and also as an alternative to commonly used reducing agents. We also fabricated chemically reduced GO (RGO) film from GO film using this method. The RGO film exhibits an electrical conductivity of about 10587 Sm⁻¹. These results suggest that this method is very useful for the reduction of GO and GO film or paper using PTSA in a solution process for flexible electronics due to its facile, efficient and cost-effective features.

  6. Strategies for Understanding and Reducing the Plasmodium vivax and Plasmodium ovale Hypnozoite Reservoir in Papua New Guinean Children: A Randomised Placebo-Controlled Trial and Mathematical Model

    PubMed Central

    Robinson, Leanne J.; Wampfler, Rahel; Betuela, Inoni; Karl, Stephan; White, Michael T.; Li Wai Suen, Connie S. N.; Hofmann, Natalie E.; Kinboro, Benson; Waltmann, Andreea; Brewster, Jessica; Lorry, Lina; Tarongka, Nandao; Samol, Lornah; Silkey, Mariabeth; Bassat, Quique; Siba, Peter M.; Schofield, Louis; Felger, Ingrid; Mueller, Ivo

    2015-01-01

    Background The undetectable hypnozoite reservoir for relapsing Plasmodium vivax and P. ovale malarias presents a major challenge for malaria control and elimination in endemic countries. This study aims to directly determine the contribution of relapses to the burden of P. vivax and P. ovale infection, illness, and transmission in Papua New Guinean children. Methods and Findings From 17 August 2009 to 20 May 2010, 524 children aged 5–10 y from East Sepik Province in Papua New Guinea (PNG) participated in a randomised double-blind placebo-controlled trial of blood- plus liver-stage drugs (chloroquine [CQ], 3 d; artemether-lumefantrine [AL], 3 d; and primaquine [PQ], 20 d, 10 mg/kg total dose) (261 children) or blood-stage drugs only (CQ, 3 d; AL, 3 d; and placebo [PL], 20 d) (263 children). Participants, study staff, and investigators were blinded to the treatment allocation. Twenty children were excluded during the treatment phase (PQ arm: 14, PL arm: 6), and 504 were followed actively for 9 mo. During the follow-up time, 18 children (PQ arm: 7, PL arm: 11) were lost to follow-up. Main primary and secondary outcome measures were time to first P. vivax infection (by qPCR), time to first clinical episode, force of infection, gametocyte positivity, and time to first P. ovale infection (by PCR). A basic stochastic transmission model was developed to estimate the potential effect of mass drug administration (MDA) for the prevention of recurrent P. vivax infections. Targeting hypnozoites through PQ treatment reduced the risk of having at least one qPCR-detectable P. vivax or P. ovale infection during 8 mo of follow-up (P. vivax: PQ arm 0.63/y versus PL arm 2.62/y, HR = 0.18 [95% CI 0.14, 0.25], p < 0.001; P. ovale: 0.06 versus 0.14, HR = 0.31 [95% CI 0.13, 0.77], p = 0.011) and the risk of having at least one clinical P. vivax episode (HR = 0.25 [95% CI 0.11, 0.61], p = 0.002). PQ also reduced the molecular force of P. vivax blood-stage infection in the first 3 mo of

  7. Dilemma in Teaching Mathematics

    ERIC Educational Resources Information Center

    Md Kamaruddin, Nafisah Kamariah; Md Amin, Zulkarnain

    2012-01-01

    The challenge in mathematics education is finding the best way to teach mathematics. When students learn the reasoning and proving in mathematics, they will be proficient in mathematics. Students must know mathematics before they can apply it. Symbolism and logic is the key to both the learning of mathematics and its effective application to…

  8. Mathematical modelling of unsteady MHD natural convection flow past a vertical plate with variable surface temperature and mass flux in the presence of radiation and chemical reaction

    NASA Astrophysics Data System (ADS)

    Raju, S. Suresh Kumar; Narahari, Marneni; Pendyala, Rajashekhar

    2016-11-01

    In the present study, a numerical analysis is made for unsteady magnetohydrodynamic (MHD) natural convective boundary-layer flow past an impulsively started semi-infinite vertical plate with variable surface temperature and mass flux in the presence of thermal radiation and chemical reaction. The Crank-Nicolson implicit finite difference technique is implemented to solve the system of governing equations. Numerical results are obtained for different values of system parameters and analyzed through graphs. The velocity profiles of the present study have been compared with the available results for the limiting case and a good agreement is found between the results.

  9. Mathematical Notation in Bibliographic Databases.

    ERIC Educational Resources Information Center

    Pasterczyk, Catherine E.

    1990-01-01

    Discusses ways in which using mathematical symbols to search online bibliographic databases in scientific and technical areas can improve search results. The representations used for Greek letters, relations, binary operators, arrows, and miscellaneous special symbols in the MathSci, Inspec, Compendex, and Chemical Abstracts databases are…

  10. Mathematical Notation in Bibliographic Databases.

    ERIC Educational Resources Information Center

    Pasterczyk, Catherine E.

    1990-01-01

    Discusses ways in which using mathematical symbols to search online bibliographic databases in scientific and technical areas can improve search results. The representations used for Greek letters, relations, binary operators, arrows, and miscellaneous special symbols in the MathSci, Inspec, Compendex, and Chemical Abstracts databases are…

  11. Mathematical Modeling of Diverse Phenomena

    NASA Technical Reports Server (NTRS)

    Howard, J. C.

    1979-01-01

    Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

  12. Mathematics Worth Teaching, Mathematics Worth Understanding.

    ERIC Educational Resources Information Center

    Romberg, Thomas A.; Kaput, James J.

    This chapter examines the scope of the mathematical content educators expect students to understand after they have participated in mathematics courses. It is organized under four headings: (1) Traditional School Mathematics, to clarify what the shift is away from; (2) Mathematics as Human Activity, to portray the direction the shift is toward;…

  13. Mathematical Literacy and Standardized Mathematical Assessments

    ERIC Educational Resources Information Center

    Matteson, Shirley M.

    2006-01-01

    Mathematical literacy is an important skill that is gaining the attention of mathematics educators. Students are increasingly challenged on standardized assessments to read, create, use, and comprehend numerous mathematical representations as a way of demonstrating mathematical literacy. Test items assessing algebra concepts from the Texas…

  14. Teachers' Mathematics as Mathematics-at-Work

    ERIC Educational Resources Information Center

    Bednarz, Nadine; Proulx, Jérôme

    2017-01-01

    Through recognising mathematics teachers as professionals who use mathematics in their workplace, this article traces a parallel between the mathematics enacted by teachers in their practice and the mathematics used in workplaces found in studies of professionals (e.g. nurses, engineers, bankers). This parallel is developed through the five…

  15. Teaching Mathematical Modeling in Mathematics Education

    ERIC Educational Resources Information Center

    Saxena, Ritu; Shrivastava, Keerty; Bhardwaj, Ramakant

    2016-01-01

    Mathematics is not only a subject but it is also a language consisting of many different symbols and relations. Taught as a compulsory subject up the 10th class, students are then able to choose whether or not to study mathematics as a main subject. The present paper discusses mathematical modeling in mathematics education. The article provides…

  16. Chemical modification of paclitaxel (Taxol) reduces P-glycoprotein interactions and increases permeation across the blood-brain barrier in vitro and in situ.

    PubMed

    Rice, Antonie; Liu, Yanbin; Michaelis, Mary Lou; Himes, Richard H; Georg, Gunda I; Audus, Kenneth L

    2005-02-10

    The purpose of this work was to introduce a chemical modification into the paclitaxel (Taxol) structure to reduce interactions with the product of the multidrug resistant type 1 (MDR1) gene, P-glycoprotein (Pgp), resulting in improved blood-brain barrier (BBB) permeability. Specifically, a taxane analogue, Tx-67, with a succinate group added at the C10 position of Taxol, was synthesized and identified as such a candidate. In comparison studies, Tx-67 had no apparent interactions with Pgp, as demonstrated by the lack of enhanced uptake of rhodamine 123 by brain microvessel endothelial cells (BMECs) in the presence of the agent. By contrast, Taxol exposure substantially enhanced rhodamine 123 uptake by BMECs through inhibition of Pgp. The transport across BMEC monolayers was polarized for both Tx-67 and Taxol with permeation in the apical to basolateral direction greater for Tx-67 and substantially reduced for Taxol relative to basolateral to apical permeation. Taxol and cyclosporin A treatments also did not enhance Tx-67 permeation across BMEC monolayers. In an in situ rat brain perfusion study, Tx-67 was demonstrated to permeate across the BBB at a greater rate than Taxol. These results demonstrate that the Taxol analogue Tx-67 had a reduced interaction with Pgp and, as a consequence, enhanced permeation across the blood-brain barrier in vitro and in situ.

  17. Backbone chemical shift assignments for Xanthomonas campestris peroxiredoxin Q in the reduced and oxidized states: a dramatic change in backbone dynamics.

    PubMed

    Buchko, Garry W; Perkins, Arden; Parsonage, Derek; Poole, Leslie B; Karplus, P Andrew

    2016-04-01

    Peroxiredoxins (Prx) are ubiquitous enzymes that reduce peroxides as part of antioxidant defenses and redox signaling. While Prx catalytic activity and sensitivity to hyperoxidative inactivation depend on their dynamic properties, there are few examples where their dynamics has been characterized by NMR spectroscopy. Here, we provide a foundation for studies of the solution properties of peroxiredoxin Q from the plant pathogen Xanthomonas campestris (XcPrxQ) by assigning the observable (1)H(N), (15)N, (13)C(α), (13)C(β), and (13)C' chemical shifts for both the reduced (dithiol) and oxidized (disulfide) states. In the reduced state, most of the backbone amide resonances (149/152, 98 %) can be assigned in the XcPrxQ (1)H-(15)N HSQC spectrum. In contrast, a remarkable 51 % (77) of these amide resonances are not visible in the (1)H-(15)N HSQC spectrum of the disulfide state of the enzyme, indicating a substantial change in backbone dynamics associated with the formation of an intramolecular C48-C84 disulfide bond.

  18. Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

    DOE PAGES

    Douglas, Erica A.; Sheng, Josephine J.; Verley, Jason C.; ...

    2015-06-04

    We found that the demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. Our work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (<460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiOx and carbon at the surface to enable germanium epitaxy. Finally, the use of this surface preparation step demonstrates anmore » alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.« less

  19. Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

    SciTech Connect

    Douglas, Erica A.; Sheng, Josephine J.; Verley, Jason C.; Carroll, Malcolm S.

    2015-06-04

    We found that the demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. Our work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (<460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiOx and carbon at the surface to enable germanium epitaxy. Finally, the use of this surface preparation step demonstrates an alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.

  20. Universal tight binding model for chemical reactions in solution and at surfaces. III. Stoichiometric and reduced surfaces of titania and the adsorption of water

    SciTech Connect

    Lozovoi, A. Y.; Sheppard, T. J.; Kohanoff, J. J.; Pashov, D. L.; Paxton, A. T.

    2014-07-28

    We demonstrate a model for stoichiometric and reduced titanium dioxide intended for use in molecular dynamics and other atomistic simulations and based in the polarizable ion tight binding theory. This extends the model introduced in two previous papers from molecular and liquid applications into the solid state, thus completing the task of providing a comprehensive and unified scheme for studying chemical reactions, particularly aimed at problems in catalysis and electrochemistry. As before, experimental results are given priority over theoretical ones in selecting targets for model fitting, for which we used crystal parameters and band gaps of titania bulk polymorphs, rutile and anatase. The model is applied to six low index titania surfaces, with and without oxygen vacancies and adsorbed water molecules, both in dissociated and non-dissociated states. Finally, we present the results of molecular dynamics simulation of an anatase cluster with a number of adsorbed water molecules and discuss the role of edge and corner atoms of the cluster.

  1. Photoelectrocatalytic reduction of CO2 into chemicals using Pt-modified reduced graphene oxide combined with Pt-modified TiO2 nanotubes.

    PubMed

    Cheng, Jun; Zhang, Meng; Wu, Gai; Wang, Xin; Zhou, Junhu; Cen, Kefa

    2014-06-17

    The photoelectrocatalytic (PEC) reduction of CO2 into high-value chemicals is beneficial in alleviating global warming and advancing a low-carbon economy. In this work, Pt-modified reduced graphene oxide (Pt-RGO) and Pt-modified TiO2 nanotubes (Pt-TNT) were combined as cathode and photoanode catalysts, respectively, to form a PEC reactor for converting CO2 into valuable chemicals. XRD, XPS, TEM, AFM, and SEM were employed to characterize the microstructures of the Pt-RGO and Pt-TNT catalysts. Reduction products, such as C2H5OH and CH3COOH, were obtained from CO2 under band gap illumination and biased voltage. A combined liquid product generation rate (CH3OH, C2H5OH, HCOOH, and CH3COOH) of approximately 600 nmol/(h·cm(2)) was observed. Carbon atom conversion rate reached 1,130 nmol/(h·cm(2)), which were much higher than those achieved using Pt-modified carbon nanotubes and platinum carbon as cathode catalysts.

  2. Early perception of stink bug damage in developing seeds of field-grown soybean induces chemical defences and reduces bug attack.

    PubMed

    Giacometti, Romina; Barneto, Jesica; Barriga, Lucia G; Sardoy, Pedro M; Balestrasse, Karina; Andrade, Andrea M; Pagano, Eduardo A; Alemano, Sergio G; Zavala, Jorge A

    2016-08-01

    Southern green stink bugs (Nezara viridula L.) invade field-grown soybean crops, where they feed on developing seeds and inject phytotoxic saliva, which causes yield reduction. Although leaf responses to herbivory are well studied, no information is available about the regulation of defences in seeds. This study demonstrated that mitogen-activated protein kinases MPK3, MPK4 and MPK6 are expressed and activated in developing seeds of field-grown soybean and regulate a defensive response after stink bug damage. Although 10-20 min after stink bug feeding on seeds induced the expression of MPK3, MPK6 and MPK4, only MPK6 was phosphorylated after damage. Herbivory induced an early peak of jasmonic acid (JA) accumulation and ethylene (ET) emission after 3 h in developing seeds, whereas salicylic acid (SA) was also induced early, and at increasing levels up to 72 h after damage. Damaged seeds upregulated defensive genes typically modulated by JA/ET or SA, which in turn reduced the activity of digestive enzymes in the gut of stink bugs. Induced seeds were less preferred by stink bugs. This study shows that stink bug damage induces seed defences, which is perceived early by MPKs that may activate defence metabolic pathways in developing seeds of field-grown soybean. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  3. Mathematical model of electrotaxis in osteoblastic cells.

    PubMed

    Vanegas-Acosta, J C; Garzón-Alvarado, D A; Zwamborn, A P M

    2012-12-01

    Electrotaxis is the cell migration in the presence of an electric field (EF). This migration is parallel to the EF vector and overrides chemical migration cues. In this paper we introduce a mathematical model for the electrotaxis in osteoblastic cells. The model is evaluated using different EF strengths and different configurations of both electrical and chemical stimuli. Accordingly, we found that the cell migration speed is described as the combination of an electrical and a chemical term. Cell migration is faster when both stimuli orient cell migration towards the same direction. In contrast, a reduced speed is obtained when the EF vector is opposed to the direction of the chemical stimulus. Numerical relations were obtained to quantify the cell migration speed at each configuration. Additional calculations for the cell colonization of a substrate also show mediation of the EF strength. Therefore, the term electro-osteoconduction is introduced to account the electrically induced cell colonization. Since numerical results compare favorably with experimental evidence, the model is suitable to be extended to other types of cells, and to numerically explore the influence of EF during wound healing. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Effect of increasing the protein-to-fat ratio and reducing fat content on the chemical and physical properties of processed cheese product.

    PubMed

    Guinee, T P; O'Callaghan, D J

    2013-01-01

    Scientific studies indicate that the intake of dietary fat and saturated fats in the modern Western diet is excessive and contributes adversely to health, lifestyle, and longevity. In response, manufacturers of cheese and processed cheese products (PCP) are pursuing the development of products with reduced fat contents. The present study investigated the effect of altering the fat level (13.8, 18.2, 22.7, 27.9, and 32.5 g/100g) in PCP on their chemical and physical properties. The PCP were formulated in triplicate to different fat levels using Cheddar cheese, skim milk cheese, anhydrous milk fat, emulsifying salt (ES), NaCl, and water. The formulations were designed to give fixed moisture (~53 g/100g) and ES:protein ratio (0.105). The resultant PCP, and their water-soluble extracts (WSE), prepared from a macerated blend of PCP and water at a weight ratio of 1:2, were analyzed at 4d. Reducing the fat content significantly increased the firmness of the unheated PCP and reduced the flowability and maximum loss tangent (fluidity) of the melted PCP. These changes coincided with increases in the levels of total protein, water-soluble protein, water-insoluble protein, and water-soluble Ca, and a decrease in the molar ratio of water-soluble Ca to soluble P. However, both water-soluble Ca and water-soluble protein decreased when expressed as percentages of total protein and total Ca, respectively, in the PCP. The high level of protein was a major factor contributing to the deterioration in physical properties as the fat content of PCP was reduced. Diluting the protein content or reducing the potential of the protein to aggregate, and thereby form structures that contribute to rigidity, may provide a means for improving quality of reduced-fat PCP by using natural cheese with lower intact casein content and lower calcium:casein ratio, for example, or by decreasing the ratio of sodium phosphate to sodium citrate-based ES.

  5. Application of Z-scan technique for the study of nonlinear absorption in chemically reduced LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Kostritskii, SM; Aillerie, M.; Kokonyan, E.; Sevostyanov, OG

    2017-07-01

    The nonlinear absorption (NLA) was studied by open-aperture Z-scan experiments in the chemically reduced nominally pure LiNbO3 crystals at cw-illumination with the red (644 nm) and green (514.5 nm) laser beams. The magnitude of the measured NLA is considerably different from the reported Z-scan results obtained in as-grown LiNbO3. The positive sign of NLA obtained with the red light has been related to the generation of the small bound polarons absorbing in red and near-IR ranges. Application of green light results in the light-induced transparency, i.e. the Z-scan traces show negative sign of NLA. Intensity dependence of Z-scan traces allows for conclusion that the photo-induced dissociation of small NbLi 4+:NbNb 4+ bipolarons and sequent generation of small polarons gives the dominating contribution to the nonlinear optical absorption in reduced crystals with a large bipolarons concentration.

  6. Blocking peripheral serotonin synthesis by telotristat etiprate (LX1032/LX1606) reduces severity of both chemical- and infection-induced intestinal inflammation.

    PubMed

    Kim, Janice J; Wang, Huaqing; Terc, Joshua D; Zambrowicz, Brian; Yang, Qi M; Khan, Waliul I

    2015-09-15

    Mucosal inflammation is accompanied by an alteration in 5-HT. Intestinal 5-HT synthesis is catalyzed by tryptophan hydroxylase 1 (Tph1) and we have shown that mice deficient in this rate-limiting enzyme have reduced severity of intestinal inflammation in models of chemical-induced experimental colitis. Here, we investigated the effect of blocking peripheral 5-HT synthesis in generation of intestinal inflammation by a using peripheral Tph inhibitor, telotristat etiprate (LX1606), in models of intestinal inflammation. LX1606 was given orally either prophylactically or therapeutically to mice with dextran sulfate sodium (DSS)-induced colitis or with infection with Trichuris muris. Severity of intestinal inflammation was measured by assessment of disease activity scores, histological damage, and MPO and inflammatory cytokine levels. LX1606 significantly reduced intestinal 5-HT levels and delayed onset and severity of DSS-induced acute and chronic colitis. This was associated with decreased MPO and proinflammatory cytokine levels compared with vehicle-treated controls. In the infection-induced inflammation model, treatment with LX1606 enhanced worm expulsion as well as increased IL-10 production and goblet cell numbers. LX1606-treated mice had significantly lower MPO and IL-1β levels compared with controls postinfection. Our results demonstrate that peripheral 5-HT plays an important role in intestinal inflammation and in the generation of immune responses. Pharmacological reduction of peripheral 5-HT may serve as a potential strategy for modulating various intestinal inflammatory disorders. Copyright © 2015 the American Physiological Society.

  7. Kinetics of Oxidation of a Reduced Form of the Cu-Based Oxygen-Carrier for Use in Chemical-Looping Combustion

    NASA Astrophysics Data System (ADS)

    Chuang, S. Y.; Dennis, J. S.; Hayhurst, A. N.; Scott, S. A.

    A co-precipitated mixture of CuO and Al2O3 is a good oxygen-carrier for chemical-looping combustion. The kinetics of regeneration of this reduced oxygen-carrier (355 - 500 urn) were measured from 300 to 750°C when reacting it with O2. Care was taken to ensure these measurements were not affected by interphase mass transfer. Efforts were also made to minimise sampling problems by using a rapid-response mass spectrometer for reactions lasting for 45 s or less; otherwise, a paramagnetic analyser for O2 was used, since the mass spectrometer drifted with time. The order of reaction with respect to O2 was found to be ˜ unity at 300 to 750°C. Below 600°C, the reduced oxygen-carrier was incompletely oxidised to a mixture of CU2O and Al2O3. Above 600°C, regeneration was completely to CuO and Al2O3 and was controlled to a considerable extent by external mass transfer. At these higher temperatures, regeneration involved a shrinking core mechanism and the two consecutive steps: 2Cu + 1/2O_2 to Cu_2 O, Cu_2 O + 1/2O_2 to 2CuO. The activation energies and pre-exponential factors for both reactions were measured from initial rates. The kinetics in the first cycle of operations were found to be similar to those in the subsequent cycles.

  8. Promoting Mathematical Argumentation

    ERIC Educational Resources Information Center

    Rumsey, Chepina; Langrall, Cynthia W.

    2016-01-01

    The Standards for Mathematical Practice (SMP) in the Common Core State Standards for Mathematics (CCSSM) (CCSSI 2010) highlight the mathematical habits that educators should be fostering in mathematics classrooms throughout K-grade 12 education. That argumentation and discourse are important components of developing mathematically proficient…

  9. Authenticity of Mathematical Modeling

    ERIC Educational Resources Information Center

    Tran, Dung; Dougherty, Barbara J.

    2014-01-01

    Some students leave high school never quite sure of the relevancy of the mathematics they have learned. They fail to see links between school mathematics and the mathematics of everyday life that requires thoughtful decision making and often complex problem solving. Is it possible to bridge the gap between school mathematics and the mathematics in…

  10. Promoting Mathematical Argumentation

    ERIC Educational Resources Information Center

    Rumsey, Chepina; Langrall, Cynthia W.

    2016-01-01

    The Standards for Mathematical Practice (SMP) in the Common Core State Standards for Mathematics (CCSSM) (CCSSI 2010) highlight the mathematical habits that educators should be fostering in mathematics classrooms throughout K-grade 12 education. That argumentation and discourse are important components of developing mathematically proficient…

  11. Applying theoretical premises of binary toxicity mathematical modeling to combined impacts of chemical plus physical agents (A case study of moderate subchronic exposures to fluoride and static magnetic field).

    PubMed

    Katsnelson, B A; Tsepilov, N A; Panov, V G; Sutunkova, M P; Varaksin, A N; Gurvich, V B; Minigalieva, I A; Valamina, I E; Makeyev, O H; Meshtcheryakova, E Y

    2016-09-01

    Sodium fluoride solution was injected i.p. to rats at a dose equivalent to 0.1 LD50 three times a week up to 18 injections. Two thirds of these rats and of the sham-injected ones were exposed to the whole body impact of a 25 mT static magnetic field for 2 or 4 h a day, 5 times a week. For mathematical analysis of the effects they produced in combination, we used a response surface model. This analysis demonstrated that (like in combined toxicity) the combined adverse action of a chemical plus a physical agent was characterized by a diversity of types depending not only on particular effects these types were assessed for but on their level as well. From this point of view, the indices for which at least one statistically significant effect was observed could be classified as identifying (1) single-factor action; (2) additivity; (3) synergism; (4) antagonism (both subadditive unidirectional action and all variants of contradirectional action). Although the classes (2) and (3) taken together encompass a smaller part of the indices, the biological importance of some of them renders the combination of agents studied as posing a higher health risk than that associated with each them acting alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Chemical chaperone treatment reduces intracellular accumulation of mutant collagen IV and ameliorates the cellular phenotype of a COL4A2 mutation that causes haemorrhagic stroke.

    PubMed

    Murray, Lydia S; Lu, Yinhui; Taggart, Aislynn; Van Regemorter, Nicole; Vilain, Catheline; Abramowicz, Marc; Kadler, Karl E; Van Agtmael, Tom

    2014-01-15

    Haemorrhagic stroke accounts for ∼20% of stroke cases and porencephaly is a clinical consequence of perinatal cerebral haemorrhaging. Here, we report the identification of a novel dominant G702D mutation in the collagen domain of COL4A2 (collagen IV alpha chain 2) in a family displaying porencephaly with reduced penetrance. COL4A2 is the obligatory protein partner of COL4A1 but in contrast to most COL4A1 mutations, the COL4A2 mutation does not lead to eye or kidney disease. Analysis of dermal biopsies from a patient and his unaffected father, who also carries the mutation, revealed that both display basement membrane (BM) defects. Intriguingly, defective collagen IV incorporation into the dermal BM was observed in the patient only and was associated with endoplasmic reticulum (ER) retention of COL4A2 in primary dermal fibroblasts. This intracellular accumulation led to ER stress, unfolded protein response activation, reduced cell proliferation and increased apoptosis. Interestingly, the absence of ER retention of COL4A2 and ER stress in cells from the unaffected father indicate that accumulation and/or clearance of mutant COL4A2 from the ER may be a critical modifier for disease development. Our analysis also revealed that mutant collagen IV is degraded via the proteasome. Importantly, treatment of patient cells with a chemical chaperone decreased intracellular COL4A2 levels, ER stress and apoptosis, demonstrating that reducing intracellular collagen accumulation can ameliorate the cellular phenotype of COL4A2 mutations. Importantly, these data highlight that manipulation of chaperone levels, intracellular collagen accumulation and ER stress are potential therapeutic options for collagen IV diseases including haemorrhagic stroke.

  13. Mathematics Models in Chemistry--An Innovation for Non-Mathematics and Non-Science Majors

    ERIC Educational Resources Information Center

    Rash, Agnes M.; Zurbach, E. Peter

    2004-01-01

    The intention of this article is to present a year-long interdisciplinary course, Mathematical Models in Chemistry. The course is comprised of eleven units, each of which has both a mathematical and a chemical component. A syllabus of the course is given and the format of the class is explained. The interaction of the professors and the content is…

  14. Mathematics Models in Chemistry--An Innovation for Non-Mathematics and Non-Science Majors

    ERIC Educational Resources Information Center

    Rash, Agnes M.; Zurbach, E. Peter

    2004-01-01

    The intention of this article is to present a year-long interdisciplinary course, Mathematical Models in Chemistry. The course is comprised of eleven units, each of which has both a mathematical and a chemical component. A syllabus of the course is given and the format of the class is explained. The interaction of the professors and the content is…

  15. Reduced pressure-chemical vapor deposition of Ge thick layers on Si(001) for 1.3-1.55-μm photodetection

    NASA Astrophysics Data System (ADS)

    Hartmann, J. M.; Abbadie, A.; Papon, A. M.; Holliger, P.; Rolland, G.; Billon, T.; Fédéli, J. M.; Rouvière, M.; Vivien, L.; Laval, S.

    2004-05-01

    Ge-based photodetectors operating in the low loss windows (1.3-1.6 μm) of silica fibers are highly desirable for the development of optical interconnections on silicon-on-insulator substrates. We have therefore investigated the structural and optical properties of Ge thick films grown directly onto Si(001) substrates using a production-compatible reduced pressure chemical vapor deposition system. We have first of all evidenced a Ge growth regime which is akin to a supply-limited one in the 400-750 °C temperature range (Ea=6.9 kcal mol-1). The thick Ge layers grown using a low-temperature/high-temperature approach are in a definite tensile-strain configuration, with a threading dislocation density for as-grown layers of the order of 9×108 cm-2 (annealed: <2×108 cm-2). The surface of those Ge thick layers is rather smooth, especially when considering the large lattice mismatch between Ge and Si. The root-mean-square roughness is indeed of the order of 0.6 nm (2 nm) only for as-grown (annealed) layers. A chemical mechanical polishing step followed by some Ge re-epitaxy can help in bringing the surface roughness of annealed layers down, however (0.5 nm). The Ge layers produced are of high optical quality. An absorption coefficient alpha equal to 4300 cm-1 (3400 cm-1) has indeed been found at room temperature and for a 1.55-μm wavelength for as-grown (annealed) layers. A 20-meV band-gap shrinkage with respect to bulk Ge (0.78 eV⇔0.80 eV) is observed as well in those tensile-strained Ge epilayers.

  16. Impact of combining planting date and chemical control to reduce larval densities of stem-infesting pests of sunflower in the central plains.

    PubMed

    Charlet, Laurence D; Aiken, Robert M; Meyer, Ron F; Gebre-Amlak, Assefa

    2007-08-01

    The guild of stem-infesting insect pests of sunflower, Helianthus annuus L., within the central Plains is a concern to producers chiefly due to losses caused by plant lodging from the sunflower stem weevil, Cylindrocopturus adspersus (LeConte) (Coleoptera: Curculionidae), and Dectes texanus texanus LeConte (Coleoptera: Cerambycidae). The incidence of a root boring moth, Pelochrista womonana (Kearfott) (Lepidoptera: Tortricidae), also has increased. Experiments were conducted in three locations in Colorado and Kansas during 2001-2003 to investigate the potential of combining planting date and foliar and seed treatment insecticide applications to lower insect stalk densities of these three pests. The impact of these strategies on weevil larval parasitoids also was studied. Eight sunflower stem weevil larval parasitoid species were identified. All were Hymenoptera and included the following (relative composition in parentheses): Nealiolus curculionis (Fitch) (42.6%), Nealiolus collaris (Brues) (3.2%) (Braconidae), Quadrastichus ainsliei Gahan (4.2%) (Eulophidae), Eurytoma tylodermatis Ashmead (13.1%) (Eurytomidae), Neocatolaccus tylodermae (Ashmead) (33.7%), Chlorocytus sp. (1.6%), Pteromalus sp. (0.5%) (Pteromalidae), and Eupelmus sp. (1.0%) (Eupelmidae). The results from this 3-yr study revealed that chemical control was often reliable in protecting the sunflower crop from stem pests and was relatively insensitive to application timing. Although results in some cases were mixed, overall, delayed planting can be a reliable and effective management tool for growers in the central Plains to use in reducing stem-infesting pest densities in sunflower stalks. Chemical control and planting date were compatible with natural mortality contributed by C. adspersus larval parasitoids.

  17. Mathematics and Cognition

    NASA Astrophysics Data System (ADS)

    Kasturirangan, Rajesh

    2014-07-01

    Mathematics is a human pursuit. Whether the truths of mathematics lie outside the human mind or emerge out of it, the actual practice of mathematics is conducted by human beings. In other words, human mathematics is the only kind of mathematics that we can pursue and human mathematics has to be built on top of cognitive capacities that are possessed by all human beings. Another way of stating the same claim is that mathematics is experienced by human beings using their cognitive capacities. This paper argues that exploring the experience of mathematics is a useful way to make headway on the foundations of mathematics. Focusing on the experience of mathematics is an empirical approach to the study of mathematics that sidesteps some of the thorniest debates from an earlier era about Platonism and Formalism in the foundations of mathematics.

  18. Chemical Equation Balancing.

    ERIC Educational Resources Information Center

    Blakley, G. R.

    1982-01-01

    Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)

  19. Cultural horizons for mathematics

    NASA Astrophysics Data System (ADS)

    Owens, Kay; Paraides, Patricia; Jannok Nutti, Ylva; Johansson, Gunilla; Bennet, Maria; Doolan, Pat; Peckham, Ray; Hill, John; Doolan, Frank; O'Sullivan, Dominic; Murray, Libbey; Logan, Patricia; McNair, Melissa; Sunnari, Vappu; Murray, Beatrice; Miller, Alissa; Nolan, John; Simpson, Alca; Ohrin, Christine; Doolan, Terry; Doolan, Michelle; Taylor, Paul

    2011-06-01

    As a result of a number of government reports, there have been numerous systemic changes in Indigenous education in Australia revolving around the importance of partnerships with the community. A forum with our local Dubbo community established the importance of working together and developed a model which placed the child in an ecological perspective that particularly noted the role of Elders and the place of the child in the family. However, there was also the issue of curriculum and mathematics education to be addressed. It was recognised that a colonised curriculum reduces the vision of what might be the potential for Indigenous mathematics education. This paper reports on the sharing that developed between our local community and some researchers and teachers from Sweden, Papua New Guinea and New Zealand. It has implications for recognising the impact of testing regimes, the teaching space, understanding the ways children learn, the curriculum, and teacher education. As a result of these discussions, a critical pedagogy that considers culture and place is presented as an ecocultural perspective on mathematics education. This perspective was seen as critical for the curriculum and learning experiences of Indigenous children.

  20. Mathematics Education Computer Software and Mathematics Teachers.

    ERIC Educational Resources Information Center

    Ozgun-Koca, S. Asli

    2000-01-01

    Presents results from a study that uses questionnaires to ask mathematics teachers' (N=64) opinions about mathematics education computer software. Indicates that respondents overwhelmingly favored discovery and remediation as the purpose of using software in mathematics classrooms. Teachers believed that real world situations and multiple…

  1. Mathematical Story: A Metaphor for Mathematics Curriculum

    ERIC Educational Resources Information Center

    Dietiker, Leslie

    2015-01-01

    This paper proposes a theoretical framework for interpreting the content found in mathematics curriculum in order to offer teachers and other mathematics educators comprehensive conceptual tools with which to make curricular decisions. More specifically, it describes a metaphor of "mathematics curriculum as story" and defines and…

  2. Mathematical Modelling Approach in Mathematics Education

    ERIC Educational Resources Information Center

    Arseven, Ayla

    2015-01-01

    The topic of models and modeling has come to be important for science and mathematics education in recent years. The topic of "Modeling" topic is especially important for examinations such as PISA which is conducted at an international level and measures a student's success in mathematics. Mathematical modeling can be defined as using…

  3. Discrete Mathematics and the Secondary Mathematics Curriculum.

    ERIC Educational Resources Information Center

    Dossey, John

    Discrete mathematics, the mathematics of decision making for finite settings, is a topic of great interest in mathematics education at all levels. Attention is being focused on resolving the diversity of opinion concerning the exact nature of the subject, what content the curriculum should contain, who should study that material, and how that…

  4. Reduced pressure-chemical vapor deposition of high Ge content Si/SiGe superlattices for 1.3 μm photo-detection

    NASA Astrophysics Data System (ADS)

    Masarotto, L.; Hartmann, J. M.; Bremond, G.; Rolland, G.; Papon, A. M.; Séméria, M. N.

    2003-07-01

    SiGe-based photodetectors operating at 1.3 μm are highly desirable for the development of optical interconnections on SOI substrates. We have therefore investigated the structural and optical properties of high Ge concentration Si/SiGe multi-quantum wells (MQWs) grown using a production-compatible reduced pressure-chemical vapor deposition system. The structures are designed in order to obtain dislocation-free strained SiGe layers with a band gap as low as possible. Those SiGe layers will be used as the absorbing layers in a future photodetector. Photoluminescence (PL) and X-ray diffraction are used to determine the characteristics of our MQWs and verify the strain state of the layers in the stack. Atomic force microscopy and transmission electronic microscopy enabled us to check the structural properties of such heterostructures. A PL emission corresponding to the free exciton "no phonon" transition as low as 0.895 eV at 9 K was obtained, implying that strained Si/SiGe MQWs can be produced with a band gap as low as 0.845 eV at 300 K.

  5. Ultrathin barrier AlN/GaN high electron mobility transistors grown at a dramatically reduced growth temperature by pulsed metal organic chemical vapor deposition

    SciTech Connect

    Xue, JunShuai Zhang, JinCheng Hao, Yue

    2015-07-27

    Ultrathin-barrier AlN/GaN heterostructures were grown on sapphire substrates by pulsed metal organic chemical vapor deposition (PMOCVD) using indium as a surfactant at a dramatically reduced growth temperature of 830 °C. Upon optimization of growth parameters, an electron mobility of 1398 cm{sup 2}/V s together with a two-dimensional-electron-gas density of 1.3 × 10{sup 13 }cm{sup −2} was obtained for a 4 nm thick AlN barrier. The grown structures featured well-ordered parallel atomic steps with a root-mean-square roughness of 0.15 nm in a 5 × 5 μm{sup 2} area revealed by atomic-force-microscopic image. Finally, the potential of such structures for device application was demonstrated by fabricating and testing under dc operation AlN/GaN high-electron-mobility transistors. These results indicate that this low temperature PMOCVD growth technique is promising for the fabrication of GaN-based electronic devices.

  6. Chemically induced conditional rescue of the reduced epidermal fluorescence8 mutant of Arabidopsis reveals rapid restoration of growth and selective turnover of secondary metabolite pools.

    PubMed

    Kim, Jeong Im; Ciesielski, Peter N; Donohoe, Bryon S; Chapple, Clint; Li, Xu

    2014-02-01

    The phenylpropanoid pathway is responsible for the biosynthesis of diverse and important secondary metabolites including lignin and flavonoids. The reduced epidermal fluorescence8 (ref8) mutant of Arabidopsis (Arabidopsis thaliana), which is defective in a lignin biosynthetic enzyme p-coumaroyl shikimate 3'-hydroxylase (C3'H), exhibits severe dwarfism and sterility. To better understand the impact of perturbation of phenylpropanoid metabolism on plant growth, we generated a chemically inducible C3'H expression construct and transformed it into the ref8 mutant. Application of dexamethasone to these plants greatly alleviates the dwarfism and sterility and substantially reverses the biochemical phenotypes of ref8 plants, including the reduction of lignin content and hyperaccumulation of flavonoids and p-coumarate esters. Induction of C3'H expression at different developmental stages has distinct impacts on plant growth. Although early induction effectively restored the elongation of primary inflorescence stem, application to 7-week-old plants enabled them to produce new rosette inflorescence stems. Examination of hypocotyls of these plants revealed normal vasculature in the newly formed secondary xylem, presumably restoring water transport in the mutant. The ref8 mutant accumulates higher levels of salicylic acid than the wild type, but depletion of this compound in ref8 did not relieve the mutant's growth defects, suggesting that the hyperaccumulation of salicylic acid is unlikely to be responsible for dwarfism in this mutant.

  7. The Epidermal Growth Factor Receptor (EGFR) Inhibitor Gefitinib Reduces but Does Not Prevent Tumorigenesis in Chemical and Hormonal Induced Hepatocarcinogenesis Rat Models

    PubMed Central

    Ribback, Silvia; Sailer, Verena; Böhning, Enrico; Günther, Julia; Merz, Jaqueline; Steinmüller, Frauke; Utpatel, Kirsten; Cigliano, Antonio; Peters, Kristin; Pilo, Maria G.; Evert, Matthias; Calvisi, Diego F.; Dombrowski, Frank

    2016-01-01

    Activation of the epidermal growth factor receptor (EGFR) signaling pathway promotes the development of hepatocellular adenoma (HCA) and carcinoma (HCC). The selective EGFR inhibitor Gefitinib was found to prevent hepatocarcinogenesis in rat cirrhotic livers. Thus, Gefitinib might reduce progression of pre-neoplastic liver lesions to HCC. In short- and long-term experiments, administration of N-Nitrosomorpholine (NNM) or intrahepatic transplantation of pancreatic islets in diabetic (PTx), thyroid follicles in thyroidectomized (TTx) and ovarian fragments in ovariectomized (OTx) rats was conducted for the induction of foci of altered hepatocytes (FAH). Gefitinib was administered for two weeks (20 mg/kg) or three and nine months (10 mg/kg). In NNM-treated rats, Gefitinib administration decreased the amount of FAH when compared to controls. The amount of HCA and HCC was decreased, but development was not prevented. Upon all transplantation models, proliferative activity of FAH was lower after administration of Gefitinib in short-term experiments. Nevertheless, the burden of HCA and HCC was not changed in later stages. Thus, EGFR inhibition by Gefitinib diminishes chemical and hormonal also induced hepatocarcinogenesis in the initiation stage in the non-cirrhotic liver. However, progression to malignant hepatocellular tumors was not prevented, indicating only a limited relevance of the EGFR signaling cascade in later stages of hepatocarcinogenesis. PMID:27669229

  8. Mathematical Ability Relies on Knowledge, Too

    ERIC Educational Resources Information Center

    Sweller, John; Clark, Richard E.; Kirschner, Paul A.

    2011-01-01

    Recent "reform" curricula both ignore the absence of supporting data and completely misunderstand the role of problem solving in cognition. If, the argument goes, teachers are not really teaching people mathematics but rather are teaching them some form of general problem solving, then mathematical content can be reduced in importance. According…

  9. It's all just mathematics

    NASA Astrophysics Data System (ADS)

    Tegmark, Max

    2014-02-01

    The world can be described using mathematical equations and numbers, but why does maths do it so well? In his new book Our Mathematical Universe, a section of which is abridged and edited here, Max Tegmark makes the radical proposal that our reality isn't just described by mathematics - it is mathematics.

  10. Learning To Talk Mathematics.

    ERIC Educational Resources Information Center

    Lo, Jane-Jane; And Others

    Calls for increased student involvement in mathematics classroom learning situations are due primarily to the recognition that a traditional lecture/demonstration format within school mathematics instruction is not effective in fostering and promoting students' problem-solving abilities, mathematical reasoning power, and mathematical communication…

  11. Students as Mathematics Consultants

    ERIC Educational Resources Information Center

    Jensen, Jennifer L.

    2013-01-01

    If students are going to develop reasoning and thinking skills, use their mathematical knowledge, and recognize the relevance of mathematics in their lives, they need to experience mathematics in meaningful ways. Only then will their mathematical skills be transferrable to all other parts of their lives. To promote such flexible mathematical…

  12. Mathematics Lessons without ...

    ERIC Educational Resources Information Center

    Cross, Kath; Hibbs, John

    2006-01-01

    In the Association of Teachers of Mathematics (ATM) Easter conference, 2006, the authors presented a list of important aspects of mathematics lessons, recommended for students to have a positive attitude to mathematics and for teachers to acquire effective teaching. The following are discussed in detail: (1) Mathematics lessons without good…

  13. Functioning Mathematically: 1

    ERIC Educational Resources Information Center

    Cain, David

    2007-01-01

    This article presents the first part of the closing address given by the author to the 2007 Association of Teachers of Mathematics (ATM) Easter conference at Loughborough. In his closing address, the author focuses on functioning mathematically as opposed to functional mathematics. His view of functional mathematics is that the focus is on someone…

  14. Mathematics "Is" Motivating

    ERIC Educational Resources Information Center

    Ricks, Thomas E.

    2010-01-01

    Mathematics is motivating; at least, it should be. I argue that mathematical activity is an inherently attractive enterprise for human beings because as intellectual organisms, we are naturally enticed by the intellectual stimulation of mathematizing, and, as social beings, we are drawn to the socializing aspects of mathematical activity. These…

  15. Computer Mathematics: An Introduction.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn, NY. Div. of Curriculum and Instruction.

    This document describes a mathematics course that uses the computer to solve mathematics problems. It was developed to be used with students who have completed at least one year of general mathematics or are not achieving success in the traditional mathematics program. The course is intended to review, reinforce, and extend concepts included in…

  16. Using Mathematics, Mathematical Applications, Mathematical Modelling, and Mathematical Literacy: A Theoretical Study

    ERIC Educational Resources Information Center

    Mumcu, Hayal Yavuz

    2016-01-01

    The purpose of this theoretical study is to explore the relationships between the concepts of using mathematics in the daily life, mathematical applications, mathematical modelling, and mathematical literacy. As these concepts are generally taken as independent concepts in the related literature, they are confused with each other and it becomes…

  17. Transforming Primary Mathematics

    ERIC Educational Resources Information Center

    Askew, Mike

    2011-01-01

    What is good mathematics teaching? What is mathematics teaching good for? Who is mathematics teaching for? These are just some of the questions addressed in "Transforming Primary Mathematics", a highly timely new resource for teachers which accessibly sets out the key theories and latest research in primary maths today. Under-pinned by findings…

  18. Functioning Mathematically: 1

    ERIC Educational Resources Information Center

    Cain, David

    2007-01-01

    This article presents the first part of the closing address given by the author to the 2007 Association of Teachers of Mathematics (ATM) Easter conference at Loughborough. In his closing address, the author focuses on functioning mathematically as opposed to functional mathematics. His view of functional mathematics is that the focus is on someone…

  19. Mathematics Lessons without ...

    ERIC Educational Resources Information Center

    Cross, Kath; Hibbs, John

    2006-01-01

    In the Association of Teachers of Mathematics (ATM) Easter conference, 2006, the authors presented a list of important aspects of mathematics lessons, recommended for students to have a positive attitude to mathematics and for teachers to acquire effective teaching. The following are discussed in detail: (1) Mathematics lessons without good…

  20. Students as Mathematics Consultants

    ERIC Educational Resources Information Center

    Jensen, Jennifer L.

    2013-01-01

    If students are going to develop reasoning and thinking skills, use their mathematical knowledge, and recognize the relevance of mathematics in their lives, they need to experience mathematics in meaningful ways. Only then will their mathematical skills be transferrable to all other parts of their lives. To promote such flexible mathematical…

  1. Transforming Primary Mathematics

    ERIC Educational Resources Information Center

    Askew, Mike

    2011-01-01

    What is good mathematics teaching? What is mathematics teaching good for? Who is mathematics teaching for? These are just some of the questions addressed in "Transforming Primary Mathematics", a highly timely new resource for teachers which accessibly sets out the key theories and latest research in primary maths today. Under-pinned by findings…

  2. Computational Mathematics

    DTIC Science & Technology

    2012-03-06

    Marsha Berger, NYU) Inclusion of the Adaptation/Adjoint module, Embedded Boundary Methods in the software package Cart3D --- Transition to NASA...ONR, DOE, AFRL, DIA Cart3D used for computing Formation Flight to reduce drag and improve energy efficiency Application to Explosively Formed

  3. Women with Multiple Chemical Sensitivity Have Increased Harm Avoidance and Reduced 5-HT1A Receptor Binding Potential in the Anterior Cingulate and Amygdala

    PubMed Central

    Åhs, Fredrik; Savic, Ivanka

    2013-01-01

    Multiple chemical sensitivity (MCS) is a common condition, characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the underlying mechanisms are unknown. Contrary to the expectations it was recently found that persons with MCS activate the odor-processing brain regions less than controls, while their activation of the anterior cingulate cortex (ACC) is increased. The present follow-up study was designed to test the hypotheses that MCS subjects have increased harm avoidance and deviations in the serotonin system, which could render them intolerant to environmental odors. Twelve MCS and 11 control subjects, age 22–44, all working or studying females, were included in a PET study where 5-HT1A receptor binding potential (BP) was assessed after bolus injection of [11C]WAY100635. Psychological profiles were assessed by the Temperament and Character Inventory and the Swedish universities Scales of Personality. All MCS and 12 control subjects were also tested for emotional startle modulation in an acoustic startle test. MCS subjects exhibited significantly increased harm avoidance, and anxiety compared to controls. They also had a reduced 5-HT1A receptor BP in amygdala (p = 0.029), ACC (p = 0.005) (planned comparisons, significance level 0.05), and insular cortex (p = 0.003; significance level p<0.005 with Bonferroni correction), and showed an inverse correlation between degree of anxiety and the BP in the amygdala (planned comparison). No group by emotional category difference was found in the startle test. Increased harm avoidance and the observed changes in the 5-HT1A receptor BP in the regions processing harm avoidance provides a plausible pathophysiological ground for the symptoms described in MCS, and yields valuable information for our general understanding of idiopathic environmental intolerances. PMID:23349968

  4. Antagonistic activity of Bacillus sp. obtained from an Algerian oilfield and chemical biocide THPS against sulfate-reducing bacteria consortium inducing corrosion in the oil industry.

    PubMed

    Gana, Mohamed Lamine; Kebbouche-Gana, Salima; Touzi, Abdelkader; Zorgani, Mohamed Amine; Pauss, André; Lounici, Hakim; Mameri, Nabil

    2011-03-01

    The present study enlightens the role of the antagonistic potential of nonpathogenic strain B21 against sulfate-reducing bacteria (SRB) consortium. The inhibitor effects of strain B21 were compared with those of the chemical biocide tetrakishydroxymethylphosphonium sulfate (THPS), generally used in the petroleum industry. The biological inhibitor exhibited much better and effective performance. Growth of SRB in coculture with bacteria strain B21 antagonist exhibited decline in SRB growth, reduction in production of sulfides, with consumption of sulfate. The observed effect seems more important in comparison with the effect caused by the tested biocide (THPS). Strain B21, a dominant facultative aerobic species, has salt growth requirement always above 5% (w/v) salts with optimal concentration of 10-15%. Phylogenetic analysis based on partial 16S rRNA gene sequences showed that strain B21 is a member of the genus Bacillus, being most closely related to Bacillus qingdaonensis DQ115802 (94.0% sequence similarity), Bacillus aidingensis DQ504377 (94.0%), and Bacillus salarius AY667494 (92.2%). Comparative analysis of partial 16S rRNA gene sequence data plus physiological, biochemical, and phenotypic features of the novel isolate and related species of Bacillus indicated that strain B21 may represent a novel species within the genus Bacillus, named Bacillus sp. (EMBL, FR671419). The results of this study indicate the application potential of Bacillus strain B21 as a biocontrol agent to fight corrosion in the oil industry.

  5. A novel chemically modified curcumin reduces inflammation-mediated connective tissue breakdown in a rat model of diabetes: periodontal and systemic effects.

    PubMed

    Elburki, M S; Moore, D D; Terezakis, N G; Zhang, Y; Lee, H-M; Johnson, F; Golub, L M

    2017-04-01

    Periodontal disease is the most common chronic inflammatory disease known to mankind (and the major cause of tooth loss in the adult population) and has also been linked to various systemic diseases, particularly diabetes mellitus. Based on the literature linking periodontal disease with diabetes in a "bidirectional manner", the objectives of the current study were to determine: (i) the effect of a model of periodontitis, complicated by diabetes, on mechanisms of tissue breakdown including bone loss; and (ii) the response of the combination of this local and systemic phenotype to a novel pleiotropic matrix metalloproteinase inhibitor, chemically modified curcumin (CMC) 2.24. Diabetes was induced in adult male rats by intravenous injection of streptozotocin (nondiabetic rats served as controls), and Escherichia coli endotoxin (lipopolysaccharide) was repeatedly injected into the gingiva to induce periodontitis. CMC 2.24 was administered by oral gavage (30 mg/kg) daily; untreated diabetic rats received vehicle alone. After 3 wk of treatment, the rats were killed, and gingiva, jaws, tibia and skin were collected. The maxillary jaws and tibia were dissected and radiographed. The gingival tissues of each experimental group (n = 6 rats/group) were pooled, extracted, partially purified and, together with individual skin samples, analyzed for matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography; MMP-8 was analyzed in gingival and skin tissue extracts, and in serum, by western blotting. The levels of three bone-resorptive cytokines [interleukin (IL)-1β, IL-6 and tumor necrosis factor-α], were measured in gingival tissue extracts and serum by ELISA. Systemic administration of CMC 2.24 to diabetic rats with endotoxin-induced periodontitis significantly inhibited alveolar bone loss and attenuated the severity of local and systemic inflammation. Moreover, this novel tri-ketonic phenylaminocarbonyl curcumin (CMC 2.24) appeared to reduce the pathologically excessive

  6. Mass Transfer with Chemical Reaction.

    ERIC Educational Resources Information Center

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  7. Mass Transfer with Chemical Reaction.

    ERIC Educational Resources Information Center

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  8. Phthalocyanine as a chemically inert, redox-active ligand: structural and electronic properties of a Nb(IV)-oxo complex incorporating a highly reduced phthalocyanine(4-) anion.

    PubMed

    Wong, Edwin W Y; Walsby, Charles J; Storr, Tim; Leznoff, Daniel B

    2010-04-05

    This report describes the reduction of a niobium(V) phthalocyanine complex and investigation of the electronic structure of the resulting products. The reduction of PcNbCl(3) (Pc = phthalocyanine dianion) with 5.5 equiv of potassium graphite in 1,2-dimethoxyethane (DME) resulted in the isolation of K(2)PcNbO.5DME (1a). Addition of 18-crown-6 to 1a gave [K(18-crown-6)](2)(mu-DME)PcNbO (1b). Both 1a and 1b were structurally characterized by single-crystal X-ray diffraction analysis. In both complexes, the niobium center adopts a square pyramidal geometry and is coordinated by four basal Pc nitrogen atoms and an apical oxo ligand. Notably, the Pc ligand in 1a is saddle-shaped, with significant bond length alternation, rather than flat with delocalized bonding. The production of ethylene during the reduction of PcNbCl(3), detected by gas chromatography/mass spectrometry (GC/MS), suggests that the oxo ligand likely results from double C-O bond activation of DME solvent. A combination of spectroscopic techniques and density functional theory (DFT) calculations were used to establish the electronic structure of 1a. The close correspondence of the electronic absorption spectrum of 1a to that of [PcZn](2-) with a di-reduced Pc(4-) ligand, indicates a similar electronic structure for the two complexes. Evaluation of the electronic transitions for 1a and [PcZn](2-) by time-dependent DFT calculations further suggests a similar electronic structure for both complexes, indicating that differences in symmetry between 1a and [PcZn](2-) do not significantly affect the nature of the electronic transitions. Electron paramagnetic resonance (EPR) spectroscopy of 1a in solution at room temperature gave a 10-line spectrum, while frozen-solution X- and Q-band EPR spectra are consistent with powder-pattern spectra defined by uniaxial g and (93)Nb hyperfine tensors: these imply the presence of a d(1) Nb(IV) metal center. EPR and electron nuclear double resonance spectroscopy suggests that

  9. Mathematics Coursework Regulates Growth in Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, Xin; Wilkins, Jesse L. M.

    2007-01-01

    Using data from the Longitudinal Study of American Youth (LSAY), we examined the extent to which students' mathematics coursework regulates (influences) the rate of growth in mathematics achievement during middle and high school. Graphical analysis showed that students who started middle school with higher achievement took individual mathematics…

  10. Mathematics for Language, Language for Mathematics

    ERIC Educational Resources Information Center

    Prochazkova, Lenka Tejkalova

    2013-01-01

    The author discusses the balance and mutual influence of the language of instruction and mathematics in the context of CLIL, Content and Language Integrated Learning. Different aspects of the relationship of language and Mathematics teaching and learning are discussed: the benefits of using a foreign language of instruction, as well as the…

  11. Mathematics Coursework Regulates Growth in Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, Xin; Wilkins, Jesse L. M.

    2007-01-01

    Using data from the Longitudinal Study of American Youth (LSAY), we examined the extent to which students' mathematics coursework regulates (influences) the rate of growth in mathematics achievement during middle and high school. Graphical analysis showed that students who started middle school with higher achievement took individual mathematics…

  12. Mathematics and Sports. Mathematical World. Volume 3.

    ERIC Educational Resources Information Center

    Sadovskii, L. E.; Sadovskii, A. L.

    This volume contains some examples of mathematical applications in sports. Sports discussed include tennis, figure skating, gymnastics, track and field, soccer, skiing, hockey, and swimming. Problems and situations are posed and answers with thorough explanations are provided. Chapters include: (1) Mathematics and Sports; (2) What Is Applied…

  13. Discover Mathematical Knowledge through Recreational Mathematics Problems

    ERIC Educational Resources Information Center

    Sodhi, Amar

    2004-01-01

    The way in which a mathematical problem was used as a vehicle to introduce the joy of mathematical research to a high school student is demonstrated. The student was interested in learning about other classical problems delighting an eager high school student.

  14. Mathematical and statistical analysis

    NASA Technical Reports Server (NTRS)

    Houston, A. Glen

    1988-01-01

    The goal of the mathematical and statistical analysis component of RICIS is to research, develop, and evaluate mathematical and statistical techniques for aerospace technology applications. Specific research areas of interest include modeling, simulation, experiment design, reliability assessment, and numerical analysis.

  15. Developing My Mathematics Identity

    ERIC Educational Resources Information Center

    Gonzalez, Lidia

    2016-01-01

    Assuming the role of storyteller, the author uses her experiences as a graduate student and beginning teacher to reflect critically on issues related to mathematics, mathematics education, gender, and diversity.

  16. Developing My Mathematics Identity

    ERIC Educational Resources Information Center

    Gonzalez, Lidia

    2016-01-01

    Assuming the role of storyteller, the author uses her experiences as a graduate student and beginning teacher to reflect critically on issues related to mathematics, mathematics education, gender, and diversity.

  17. Students' Mathematical Noticing

    ERIC Educational Resources Information Center

    Lobato, Joanne; Hohensee, Charles; Rhodehamel, Bohdan

    2013-01-01

    Even in simple mathematical situations, there is an array of different mathematical features that students can attend to or notice. What students notice mathematically has consequences for their subsequent reasoning. By adapting work from both cognitive science and applied linguistics anthropology, we present a focusing framework, which treats…

  18. Mathematics, Programming, and STEM

    ERIC Educational Resources Information Center

    Yeh, Andy; Chandra, Vinesh

    2015-01-01

    Learning mathematics is a complex and dynamic process. In this paper, the authors adopt a semiotic framework (Yeh & Nason, 2004) and highlight programming as one of the main aspects of the semiosis or meaning-making for the learning of mathematics. During a 10- week teaching experiment, mathematical meaning-making was enriched when primary…

  19. Who Can Know Mathematics?

    ERIC Educational Resources Information Center

    Walshaw, Margaret

    2014-01-01

    This paper explores contemporary thinking about learning mathematics, and within that, social justice within mathematics education. The discussion first looks at mechanisms offered by conventional explanations on the emancipatory project and then moves towards more recent insights developed within mathematics education. Synergies are drawn between…

  20. Mathematics and Sports

    ERIC Educational Resources Information Center

    Gallian, Joseph A., Ed.

    2010-01-01

    "Mathematics and Sports", edited by Joseph A. Gallian, gathers 25 articles that illuminate the power and role of mathematics in the worlds of professional and recreational play. Divided into sections by the kind of sports, the book offers source materials for classroom use and student projects. Readers will encounter mathematical ideas from an…

  1. Mathematics in Masons' Workplace

    ERIC Educational Resources Information Center

    Moreira, Darlinda; Pardal, Eugénia

    2012-01-01

    This paper presents masons' professional practices, which are related to mathematics. It aims to contribute to the area of adult mathematics education and to enlarge knowledge about how mathematics is used at the workplace. Methodologically it was followed an ethnographic approach. The key informants of the study were four masons aged between 40…

  2. Mathematics and Mobile Learning

    ERIC Educational Resources Information Center

    Sayed, Fayez

    2015-01-01

    The wide range of Mathematical Apps targeting different mathematical concepts and the various types of mobile devices available present a demanding and challenging problem to the teaching and learning in the field of mathematics. In an attempt to address this issue, a few Apps were selected, implemented and tested in this work. [For complete…

  3. Mathematics and Global Survival.

    ERIC Educational Resources Information Center

    Schwartz, Richard H.

    This resource was written to provide students with an awareness of critical issues facing the world today. In courses for college students, it can motivate their study of mathematics, teach them how to solve mathematical problems related to current global issues, provide coherence to mathematical studies through a focus on issues of human…

  4. Mathematics Teaching Today

    ERIC Educational Resources Information Center

    Martin, Tami S.; Speer, William R.

    2009-01-01

    This article describes features, consistent messages, and new components of "Mathematics Teaching Today: Improving Practice, Improving Student Learning" (NCTM 2007), an updated edition of "Professional Standards for Teaching Mathematics" (NCTM 1991). The new book describes aspects of high-quality mathematics teaching; offers a model for observing,…

  5. Mathenger Hunt: Mathematics Matters.

    ERIC Educational Resources Information Center

    Falba, Christy J.; Weiss, Maria J.

    1991-01-01

    Presented is an activity which shows how mathematics is used in real life and helps to establish a need for mathematics in students' futures. Adapted from a scavenger-hunt idea, this activity helps students to discover that almost every career makes use of mathematics. (KR)

  6. A Mathematical Diet Model

    ERIC Educational Resources Information Center

    Toumasis, Charalampos

    2004-01-01

    Emphasis on problem solving and mathematical modeling has gained considerable attention in the last few years. Connecting mathematics to other subjects and to the real world outside the classroom has received increased attention in mathematics programs. This article describes an application of simple differential equations in the field of…

  7. Who Can Know Mathematics?

    ERIC Educational Resources Information Center

    Walshaw, Margaret

    2014-01-01

    This paper explores contemporary thinking about learning mathematics, and within that, social justice within mathematics education. The discussion first looks at mechanisms offered by conventional explanations on the emancipatory project and then moves towards more recent insights developed within mathematics education. Synergies are drawn between…

  8. Mathematics. [SITE 2001 Section].

    ERIC Educational Resources Information Center

    Connell, Michael L., Ed.; Lowery, Norene Vail, Ed.; Harnisch, Delwyn L., Ed.

    This document contains the following papers on mathematics from the SITE (Society for Information Technology & Teacher Education) 2001 conference: "Secondary Mathematics Methods Course with Technology Units: Encouraging Pre-Service Teachers To Use Technology" (Rajee Amarasinghe); "Competency Exams in College Mathematics"…

  9. Eleventh Year Mathematics.

    ERIC Educational Resources Information Center

    Buchman, Aaron; Zimmerman, Robert

    This outline for Eleventh Year Mathematics in New York adheres closely to the recommendations of The Commission of Mathematics of the College Entrance Examination Board and thus presents a unified development of certain aspects of algebra, trigonometry, and analytic geometry. Its aim is both as a terminal course in mathematics and as a solid…

  10. Mathematics and Language Experience.

    ERIC Educational Resources Information Center

    McGhee, Joyce

    1995-01-01

    Presents an approach to geometry that integrates mathematics and language teaching. Suggests that mathematics is more than manipulation of numbers: it is a way of thinking about things. Argues that mathematics and language should be united especially to achieve the goal of promoting the development of analytical thinkers, as the ability to see…

  11. Applied Vocational Mathematics.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    Developed for use in teaching a two-semester, one-unit course, this course guide is intended to aid the high school instructor in teaching mathematical problem-solving and computational skills to vocational education students. The state-adopted textbook for general mathematics III, "Applied General Mathematics" serves as the major…

  12. Students' Mathematical Noticing

    ERIC Educational Resources Information Center

    Lobato, Joanne; Hohensee, Charles; Rhodehamel, Bohdan

    2013-01-01

    Even in simple mathematical situations, there is an array of different mathematical features that students can attend to or notice. What students notice mathematically has consequences for their subsequent reasoning. By adapting work from both cognitive science and applied linguistics anthropology, we present a focusing framework, which treats…

  13. Teaching for Learning Mathematics

    ERIC Educational Resources Information Center

    Sutherland, Ros

    2006-01-01

    This book explores the factors that influence young people's learning of mathematics. It uses a holistic, socio-culturally informed approach to show how all young people can be encouraged to engage with and learn mathematics. Rich examples from classroom practice are used to connect theory and practice. The role of mathematical tools, including…

  14. Contrasts in Mathematical Challenges in A-Level Mathematics and Further Mathematics, and Undergraduate Mathematics Examinations

    ERIC Educational Resources Information Center

    Darlington, Ellie

    2014-01-01

    This article describes part of a study which investigated the role of questions in students' approaches to learning mathematics at the secondary-tertiary interface, focussing on the enculturation of students at the University of Oxford. Use of the Mathematical Assessment Task Hierarchy taxonomy revealed A-level Mathematics and Further Mathematics…

  15. Mathenger Hunt: Mathematics Matters.

    ERIC Educational Resources Information Center

    Falba, Christy J.; Weiss, Maria J.

    1991-01-01

    Presented is an activity which shows how mathematics is used in real life and helps to establish a need for mathematics in students' futures. Adapted from a scavenger-hunt idea, this activity helps students to discover that almost every career makes use of mathematics. (KR)

  16. A "Mathematics Background Check"

    ERIC Educational Resources Information Center

    Hubisz, John

    2009-01-01

    Early in my career someone else reported that the best indicator of success in calculus-based physics (CBP) at our school was whether students had taken mathematics in a certain region of New Brunswick. I sat down with a very longtime mathematics teacher and asked him what he thought students should know in mathematics after high school to succeed…

  17. Translations toward Connected Mathematics

    ERIC Educational Resources Information Center

    Applebaum, Mark; Leikin, Roza

    2010-01-01

    The translation principle allows students to solve problems in different branches of mathematics and thus to develop connectedness in their mathematical knowledge. Successful application of the translation principle depends on the classroom mathematical norms for the development of discussions and the comparison of different solutions to one…

  18. Contrasts in Mathematical Challenges in A-Level Mathematics and Further Mathematics, and Undergraduate Mathematics Examinations

    ERIC Educational Resources Information Center

    Darlington, Ellie

    2014-01-01

    This article describes part of a study which investigated the role of questions in students' approaches to learning mathematics at the secondary-tertiary interface, focussing on the enculturation of students at the University of Oxford. Use of the Mathematical Assessment Task Hierarchy taxonomy revealed A-level Mathematics and Further Mathematics…

  19. Defining Mathematical Giftedness

    ERIC Educational Resources Information Center

    Parish, Linda

    2014-01-01

    This theoretical paper outlines the process of defining "mathematical giftedness" for a present study on how primary school teaching shapes the mindsets of children who are mathematically gifted. Mathematical giftedness is not a badge of honour or some special value attributed to a child who has achieved something exceptional.…

  20. Mathematics and Music.

    ERIC Educational Resources Information Center

    Nisbet, Steven

    1991-01-01

    The relationship between mathematics and music has been investigated for thousands of years. Presented are the mathematical features of music through a study of melody, harmony, and rhythm, and the musical features of mathematics through a study of pattern, ratio, modular arithmetic, Pythagorean triples, and number sequences. (MDH)

  1. Latinos and Mathematics.

    ERIC Educational Resources Information Center

    Ortiz-Franco, Luis

    An historical perspective reveals that sophisticated mathematical activity has been going on in the Latino culture for thousands of years. This paper provides a general definition of the area of mathematics education that deals with issues of culture and mathematics (ethnomathematics) and defines what is meant by the term Latino in this essay.…

  2. Creating Words in Mathematics

    ERIC Educational Resources Information Center

    Galligan, Linda

    2016-01-01

    A "National Numeracy Report" and the Australian Curriculum (2014) have recognised the importance of language in mathematics. The general capabilities contained within the "Australian Curriculum: Mathematics" (2014) highlight literacy as an important tool in the teaching and learning of mathematics, from the interpretation of…

  3. Variation and Mathematics Pedagogy

    ERIC Educational Resources Information Center

    Leung, Allen

    2012-01-01

    This discussion paper put forwards variation as a theme to structure mathematical experience and mathematics pedagogy. Patterns of variation from Marton's Theory of Variation are understood and developed as types of variation interaction that enhance mathematical understanding. An idea of a discernment unit comprising mutually supporting variation…

  4. Mathematics Teaching as Praxis

    ERIC Educational Resources Information Center

    Grootenboer, Peter; Edwards-Groves, Christine

    2014-01-01

    In this paper we argue that mathematics teaching can be conceptualised as a form of praxis. Viewing mathematics teaching as praxis foregrounds the moral nature of teaching and the educational practices that are developed in response to the educational needs in particular sites. The case for praxis in mathematics education is then made by drawing…

  5. Mathematics for Electronics.

    ERIC Educational Resources Information Center

    Clary, Joseph R.; Nery, Karen P.

    This set of 20 modules was designed for use primarily to help teach and reinforce the basic mathematics skills in electronics classes. The modules are based on electronics competencies that require mathematics skills, as determined by a panel of high school electronics and mathematics teachers. Each module consists of one or two pages of basic…

  6. Mathematics and Sports

    ERIC Educational Resources Information Center

    Gallian, Joseph A., Ed.

    2010-01-01

    "Mathematics and Sports", edited by Joseph A. Gallian, gathers 25 articles that illuminate the power and role of mathematics in the worlds of professional and recreational play. Divided into sections by the kind of sports, the book offers source materials for classroom use and student projects. Readers will encounter mathematical ideas from an…

  7. Mathematics Teaching Today

    ERIC Educational Resources Information Center

    Martin, Tami S.; Speer, William R.

    2009-01-01

    This article describes features, consistent messages, and new components of "Mathematics Teaching Today: Improving Practice, Improving Student Learning" (NCTM 2007), an updated edition of "Professional Standards for Teaching Mathematics" (NCTM 1991). The new book describes aspects of high-quality mathematics teaching; offers a model for observing,…

  8. Empowering Mathematical Practices

    ERIC Educational Resources Information Center

    Coomes, Jacqueline; Lee, Hyung Sook

    2017-01-01

    Mathematics teachers want to empower students as mathematical thinkers and doers (NCTM 2000). Specific ways of thinking and doing mathematics were described in the Process Standards (NCTM 2000); they were further characterized as habits of mind (Mark, Goldenberg, and Sword 2010); and more recently, they were detailed in the Common Core's Standards…

  9. Making Mathematics Phenomenal

    ERIC Educational Resources Information Center

    Pratt, Dave

    2012-01-01

    Mathematics is often portrayed as an "abstract" cerebral subject, beyond the reach of many. In response, research with digital technology has led to innovative design in which mathematics can be experienced much like everyday phenomena. This lecture examines how careful design can "phenomenalise" mathematics and support not only engagement but…

  10. Mathematics and mysticism.

    PubMed

    Abraham, Ralph

    2015-12-01

    Is there a world of mathematics above and beyond ordinary reality, as Plato proposed? Or is mathematics a cultural construct? In this short article we speculate on the place of mathematical reality from the perspective of the mystical cosmologies of the ancient traditions of meditation, psychedelics, and divination.

  11. Creating Words in Mathematics

    ERIC Educational Resources Information Center

    Galligan, Linda

    2016-01-01

    A "National Numeracy Report" and the Australian Curriculum (2014) have recognised the importance of language in mathematics. The general capabilities contained within the "Australian Curriculum: Mathematics" (2014) highlight literacy as an important tool in the teaching and learning of mathematics, from the interpretation of…

  12. Modern Versus Traditional Mathematics

    ERIC Educational Resources Information Center

    Roberts, A. M.

    1974-01-01

    The effect of different secondary school mathematics syllabi on first-year performance in college-level mathematics was studied in an attempt to evaluate the syllabus change. Students with a modern mathematics background performed sigficantly better on most first-year units. A topic-by-topic analysis of results is included. (DT)

  13. Mathematics in Combat

    DTIC Science & Technology

    The purpose of this book is to familiarize the reader with how mathematics can solve important problems in modern military affairs. The authors discuss and explain, without resorting to complex mathematical calculations, the essence of the basic methods which modern mathematics makes available to military problems, design and combat deployment of modern weapons.

  14. Mathematics and Chemistry

    ERIC Educational Resources Information Center

    Henson, R.; Stumbles, A.

    1977-01-01

    The relationship between mathematics and chemistry has been changing rapidly in recent years. Some chemistry teachers have experienced difficulties in their teaching with the introduction of modern mathematics in the schools. Some suggestions for reinforcing the concepts and language of modern mathematics are put forth. (Author/MA)

  15. Mathematics for Electronics.

    ERIC Educational Resources Information Center

    Clary, Joseph R.; Nery, Karen P.

    This set of 20 modules was designed for use primarily to help teach and reinforce the basic mathematics skills in electronics classes. The modules are based on electronics competencies that require mathematics skills, as determined by a panel of high school electronics and mathematics teachers. Each module consists of one or two pages of basic…

  16. Mathematics 9th Year.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn, NY. Bureau of Curriculum Development.

    The Materials in this bulletin indicate suggested teaching procedures needed to implement the teaching of "mathematics, 9th Year" as outlined in Curriculum Bulletin No. 3, 1958-59 series, Course of Study Mathematics 7-8-9. Whereas the course of study suggests the application of mathematical principles such as commutativity,…

  17. The Chicken or the Egg? The Direction of the Relationship Between Mathematics Anxiety and Mathematics Performance.

    PubMed

    Carey, Emma; Hill, Francesca; Devine, Amy; Szücs, Dénes

    2015-01-01

    This review considers the two possible causal directions between mathematics anxiety (MA) and poor mathematics performance. Either poor maths performance may elicit MA (referred to as the Deficit Theory), or MA may reduce future maths performance (referred to as the Debilitating Anxiety Model). The evidence is in conflict: the Deficit Theory is supported by longitudinal studies and studies of children with mathematical learning disabilities, but the Debilitating Anxiety Model is supported by research which manipulates anxiety levels and observes a change in mathematics performance. It is suggested that this mixture of evidence might indicate a bidirectional relationship between MA and mathematics performance (the Reciprocal Theory), in which MA and mathematics performance can influence one another in a vicious cycle.

  18. The Chicken or the Egg? The Direction of the Relationship Between Mathematics Anxiety and Mathematics Performance

    PubMed Central

    Carey, Emma; Hill, Francesca; Devine, Amy; Szücs, Dénes

    2016-01-01

    This review considers the two possible causal directions between mathematics anxiety (MA) and poor mathematics performance. Either poor maths performance may elicit MA (referred to as the Deficit Theory), or MA may reduce future maths performance (referred to as the Debilitating Anxiety Model). The evidence is in conflict: the Deficit Theory is supported by longitudinal studies and studies of children with mathematical learning disabilities, but the Debilitating Anxiety Model is supported by research which manipulates anxiety levels and observes a change in mathematics performance. It is suggested that this mixture of evidence might indicate a bidirectional relationship between MA and mathematics performance (the Reciprocal Theory), in which MA and mathematics performance can influence one another in a vicious cycle. PMID:26779093

  19. Sustainable Planning Practices in St. Joseph Watershed as a Mixed Land-Use Watershed to Reduce the Risk of Chemical Impairment of Surface Water Supplies

    USDA-ARS?s Scientific Manuscript database

    Increased population growth in St. Joseph Watershed and the mix of land-use with urban and agricultural production brings about chemical impairment of metropolitan drinking water supplies. Furthermore, the St. Joseph Watershed is not only a drinking water supply, but also it provides water for recre...

  20. Mathematics analysis of polymerase chain reaction kinetic curves.

    PubMed

    Sochivko, D G; Fedorov, A A; Varlamov, D A; Kurochkin, V E; Petrov, R V

    2016-01-01

    The paper reviews different approaches to the mathematical analysis of polymerase chain reaction (PCR) kinetic curves. The basic principles of PCR mathematical analysis are presented. Approximation of PCR kinetic curves and PCR efficiency curves by various functions is described. Several PCR models based on chemical kinetics equations are suggested. Decision criteria for an optimal function to describe PCR efficiency are proposed.

  1. Modelling Mathematical Reasoning in Physics Education

    NASA Astrophysics Data System (ADS)

    Uhden, Olaf; Karam, Ricardo; Pietrocola, Maurício; Pospiech, Gesche

    2012-04-01

    Many findings from research as well as reports from teachers describe students' problem solving strategies as manipulation of formulas by rote. The resulting dissatisfaction with quantitative physical textbook problems seems to influence the attitude towards the role of mathematics in physics education in general. Mathematics is often seen as a tool for calculation which hinders a conceptual understanding of physical principles. However, the role of mathematics cannot be reduced to this technical aspect. Hence, instead of putting mathematics away we delve into the nature of physical science to reveal the strong conceptual relationship between mathematics and physics. Moreover, we suggest that, for both prospective teaching and further research, a focus on deeply exploring such interdependency can significantly improve the understanding of physics. To provide a suitable basis, we develop a new model which can be used for analysing different levels of mathematical reasoning within physics. It is also a guideline for shifting the attention from technical to structural mathematical skills while teaching physics. We demonstrate its applicability for analysing physical-mathematical reasoning processes with an example.

  2. The History of Mathematics and Mathematical Education

    ERIC Educational Resources Information Center

    Grattan-Guinness, I.

    1977-01-01

    Answers to questions which were asked after the author's various lectures in Australia are gathered here. Topics touched upon include "new" mathematics, unknown constants and free variables, propositional functions, linear algebra, arithmetic and geometry, and student assessment. (MN)

  3. LDI-MS assisted by chemical-free gold nanoparticles: enhanced sensitivity and reduced background in the low-mass region.

    PubMed

    Amendola, Vincenzo; Litti, Lucio; Meneghetti, Moreno

    2013-12-17

    Gold nanoparticles (AuNPs) assisted laser desorption ionization mass spectrometry (LDI-MS) emerged as an effective technique for the detection of analytes with high sensitivity. The surface chemistry and the size of AuNPs are the crucial parameters for lowering the detection limits and increasing the selectivity of LDI-MS. Here we show that chemical-free size selected AuNPs, obtained by laser ablation synthesis in solution (LASiS), have very low background in the low mass region (<500 Da), contrary to citrate stabilized AuNPs (citrate-AuNPs) and dihydroxyacetophenone (DHAP). This allowed better performances for the picomole detection of low mass analytes like arginine, fructose, atrazine, anthracene and paclitaxel. The results suggest that chemical-free LASiS-AuNPs can be an excellent matrix for nanoparticle-assisted LDI-MS.

  4. Significant increases in pulping efficiency in C4H-F5H-transformed poplars: improved chemical savings and reduced environmental toxins.

    PubMed

    Huntley, Shannon K; Ellis, Dave; Gilbert, Margarita; Chapple, Clint; Mansfield, Shawn D

    2003-10-08

    The gene encoding ferulate 5-hydroxylase (F5H) was overexpressed in poplar (Populus tremula x Populus alba) using the cinnamate-4-hydroxylase (C4H) promoter to drive expression specifically in cells involved in the lignin biosynthetic pathway and was shown to significantly alter the mole percentage of syringyl subunits in the lignin, as determined by thioacidolysis. Analysis of poplar transformed with a C4H-F5H construct demonstrated significant increases in chemical (kraft) pulping efficiency from greenhouse-grown trees. Compared to wild-type wood, decreases of 23 kappa units and increases of >20 ISO brightness units were observed in trees exhibiting high syringyl monomer concentrations. These changes were associated with no significant modification in total lignin content and no observed phenotypic differences. C4H-F5H-transformed trees could increase pulp throughputs at mills by >60% while concurrently decreasing chemicals employed during processing (chemical pulping and bleaching) and, consequently, the amount of deleterious byproducts released into the environment.

  5. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    PubMed

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.

  6. Modern Chemical Technology, Volume 1.

    ERIC Educational Resources Information Center

    Pecsok, Robert L.; Chapman, Kenneth

    This volume is the first in a series of the ACS "Modern Chemical Technology" (ChemTeC) curriculum which is to prepare chemical technicians. The chapters concentrate on gas chromatography, tests for purity, properties of gases, and gas measurements. Included is the appropriate content, exercises, laboratory activities, and all needed mathematics.…

  7. Modern Chemical Technology, Volume 1.

    ERIC Educational Resources Information Center

    Pecsok, Robert L.; Chapman, Kenneth

    This volume is the first in a series of the ACS "Modern Chemical Technology" (ChemTeC) curriculum which is to prepare chemical technicians. The chapters concentrate on gas chromatography, tests for purity, properties of gases, and gas measurements. Included is the appropriate content, exercises, laboratory activities, and all needed mathematics.…

  8. Early childhood mathematics intervention.

    PubMed

    Clements, Douglas H; Sarama, Julie

    2011-08-19

    Preschool and primary grade children have the capacity to learn substantial mathematics, but many children lack opportunities to do so. Too many children not only start behind their more advantaged peers, but also begin a negative trajectory in mathematics. Interventions designed to facilitate their mathematical learning during ages 3 to 5 years have a strong positive effect on these children's lives for many years thereafter.

  9. Exploring Differential Effects of Mathematics Courses on Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, Xin; McIntyre, Laureen J.

    2005-01-01

    Using data from the Longitudinal Study of Mathematics Participation (N = 1,518 students from 34 schools), we investigated the effects of pure and applied mathematics courses on mathematics achievement, controlling for prior mathematics achievement. Results of multilevel modelling showed that the effects of pure mathematics were significant after…

  10. On Mathematical Understanding: Perspectives of Experienced Chinese Mathematics Teachers

    ERIC Educational Resources Information Center

    Cai, Jinfa; Ding, Meixia

    2017-01-01

    Researchers have long debated the meaning of mathematical understanding and ways to achieve mathematical understanding. This study investigated experienced Chinese mathematics teachers' views about mathematical understanding. It was found that these mathematics teachers embrace the view that understanding is a web of connections, which is a result…

  11. Mathematics for Teaching: A Form of Applied Mathematics

    ERIC Educational Resources Information Center

    Stylianides, Gabriel J.; Stylianides, Andreas J.

    2010-01-01

    In this article we elaborate a conceptualisation of "mathematics for teaching" as a form of applied mathematics (using Bass's idea of characterising mathematics education as a form of applied mathematics) and we examine implications of this conceptualisation for the mathematical preparation of teachers. Specifically, we focus on issues of design…

  12. On Mathematical Understanding: Perspectives of Experienced Chinese Mathematics Teachers

    ERIC Educational Resources Information Center

    Cai, Jinfa; Ding, Meixia

    2017-01-01

    Researchers have long debated the meaning of mathematical understanding and ways to achieve mathematical understanding. This study investigated experienced Chinese mathematics teachers' views about mathematical understanding. It was found that these mathematics teachers embrace the view that understanding is a web of connections, which is a result…

  13. Hands-On Mathematics: Two Cases from Ancient Chinese Mathematics

    ERIC Educational Resources Information Center

    Wang, Youjun

    2009-01-01

    In modern mathematical teaching, it has become increasingly emphasized that mathematical knowledge should be taught by problem-solving, hands-on activities, and interactive learning experiences. Comparing the ideas of modern mathematical education with the development of ancient Chinese mathematics, we find that the history of mathematics in…

  14. A Capstone Mathematics Course for Prospective Secondary Mathematics Teachers

    ERIC Educational Resources Information Center

    Artzt, Alice F.; Sultan, Alan; Curcio, Frances R.; Gurl, Theresa

    2012-01-01

    This article describes an innovative capstone mathematics course that links college mathematics with school mathematics and pedagogy. It describes how college juniors in a secondary mathematics teacher preparation program engage in leadership experiences that enable them to learn mathematics for teaching while developing student-centered…

  15. Using Mathematics Literature with Prospective Secondary Mathematics Teachers

    ERIC Educational Resources Information Center

    Jett, Christopher C.

    2014-01-01

    Literature in mathematics has been found to foster positive improvements in mathematics learning. This manuscript reports on a mathematics teacher educator's use of literature via literature circles with 11 prospective secondary mathematics teachers in a mathematics content course. Using survey and reflection data, the author found that…

  16. Finite Mathematics and Discrete Mathematics: Is There a Difference?

    ERIC Educational Resources Information Center

    Johnson, Marvin L.

    Discrete mathematics and finite mathematics differ in a number of ways. First, finite mathematics has a longer history and is therefore more stable in terms of course content. Finite mathematics courses emphasize certain particular mathematical tools which are useful in solving the problems of business and the social sciences. Discrete mathematics…

  17. A Capstone Mathematics Course for Prospective Secondary Mathematics Teachers

    ERIC Educational Resources Information Center

    Artzt, Alice F.; Sultan, Alan; Curcio, Frances R.; Gurl, Theresa

    2012-01-01

    This article describes an innovative capstone mathematics course that links college mathematics with school mathematics and pedagogy. It describes how college juniors in a secondary mathematics teacher preparation program engage in leadership experiences that enable them to learn mathematics for teaching while developing student-centered…

  18. Using Mathematics Literature with Prospective Secondary Mathematics Teachers

    ERIC Educational Resources Information Center

    Jett, Christopher C.

    2014-01-01

    Literature in mathematics has been found to foster positive improvements in mathematics learning. This manuscript reports on a mathematics teacher educator's use of literature via literature circles with 11 prospective secondary mathematics teachers in a mathematics content course. Using survey and reflection data, the author found that…

  19. Affect and Mathematics: Persistence in the Mathematical Environment.

    ERIC Educational Resources Information Center

    Blum-Anderson, Judy

    The attitudes and beliefs that students hold about the subject of mathematics and about themselves as learners of mathematics contribute as much to the school's mathematical environment as do the concrete and cognitive aspects of mathematics. This paper considers the effects of mathematical affect and the use of intervention programs to increase…

  20. Finite Mathematics and Discrete Mathematics: Is There a Difference?

    ERIC Educational Resources Information Center

    Johnson, Marvin L.

    Discrete mathematics and finite mathematics differ in a number of ways. First, finite mathematics has a longer history and is therefore more stable in terms of course content. Finite mathematics courses emphasize certain particular mathematical tools which are useful in solving the problems of business and the social sciences. Discrete mathematics…

  1. Photoreduction of carbon dioxide by aqueous ferrous ion: An alternative to the strongly reducing atmosphere for the chemical origin of life

    PubMed Central

    Borowska, Zofia; Mauzerall, David

    1988-01-01

    We have shown that ferrous ion at neutral pH photoreduces water to hydrogen with a high quantum yield on excitation with near-ultraviolet light. This simple system also efficiently reduces carbon dioxide (bicarbonate ions) to formaldehyde. Overall, these reactions offer a solution to a dilemma confronting the standard or Oparin-Urey model of the origin of life. If carbon dioxide was the main form of carbon on the primitive earth, the ferrous photoreaction would have provided the reduced carbon necessary to form amino acids and other biogenetic molecules. We believe this system may have been the progenitor to the biological photosynthetic systems. PMID:16593977

  2. Philosophy and mathematics: interactions.

    PubMed

    Rashed, Roshdi

    From Plato to the beginnings of the last century, mathematics provided philosophers with methods of exposition, procedures of demonstration, and instruments of analysis. The unprecedented development of mathematics on the one hand, and the mathematicians' appropriation of Logic from the philosophers on the other hand, have given rise to two problems with which the philosophers have to contend: (1) Is there still a place for the philosophy of mathematics? and (2) To what extent is a philosophy of mathematics still possible? This article offers some reflections on these questions, which have preoccupied a good many philosophers and continue to do so.

  3. Collective Surfing of Chemically Active Particles

    NASA Astrophysics Data System (ADS)

    Masoud, Hassan; Shelley, Michael J.

    2014-03-01

    We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

  4. Collective surfing of chemically active particles.

    PubMed

    Masoud, Hassan; Shelley, Michael J

    2014-03-28

    We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

  5. Physico-chemical and sensory properties of reduced-fat mortadella prepared with blends of calcium, magnesium and potassium chloride as partial substitutes for sodium chloride.

    PubMed

    Horita, C N; Morgano, M A; Celeghini, R M S; Pollonio, M A R

    2011-12-01

    Blends of calcium, magnesium and potassium chloride were used to partially replace sodium chloride (50-75%) in reduced-fat mortadella formulations. The presence of calcium chloride reduced the emulsion stability, cooking yield, elasticity and cohesiveness and increased hardness; however, it yielded the best sensory acceptance when 50% NaCl was replaced by 25% CaCl(2) and 25% KCl. There was no effect of the salt substitutes on mortadella color, appearance and aroma. All salt combinations studied showed stable lipid oxidation during its shelf life. The use of a blend with 1% NaCl, 0.5% KCl and 0.5% MgCl(2) resulted in the best emulsion stability, but the worst scores for flavor. This study suggests that it is possible to reduce the sodium chloride concentration by 50% in reduced-fat mortadella using the studied salt combinations with necessary adjustments to optimize the sensory properties (MgCl(2) 25%; KCl 25%) or emulsion stability (CaCl(2) 25%; KCl 25%).

  6. Effects of Dietary Fiber Extracted from Pumpkin (Cucurbita maxima Duch.) on the Physico-Chemical and Sensory Characteristics of Reduced-Fat Frankfurters.

    PubMed

    Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun; Kim, Young-Boong; Choi, Yun-Sang

    2016-01-01

    In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties.

  7. Effects of Dietary Fiber Extracted from Pumpkin (Cucurbita maxima Duch.) on the Physico-Chemical and Sensory Characteristics of Reduced-Fat Frankfurters

    PubMed Central

    Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun

    2016-01-01

    In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties. PMID:27433101

  8. Reducing the Risks. In the aftermath of a terrorist attack, wastewater utilities may have to contend with decontamination water containing chemical, biological, or radiological substances

    SciTech Connect

    Warren, Linda P.; Hornback, Chris; Strom, Daniel J.

    2006-08-01

    In the aftermath of a chemical, biological, or radiological (CBR) attack, decontamination of people and infrastructure will be needed. Decontamination inevitably produces wastewater, and wastewater treatment plants (WTPs) need to know how to handle decontamination wastewater. This article describes CBR substances; planning, coordinating, and communicating responses across agencies; planning within a utility; coordination with local emergency managers and first responders; mitigating effects of decontamination wastewater; and mitigating effects on utility personnel. Planning for Decontamination Wastewater: A Guide for Utilities, the document on which this article is based, was developed under a cooperative agreement from the U.S. Environmental Protection Agency by the National Association of Clean Water Agencies (NACWA) and its contractor, CH2MHILL, Inc.

  9. The Characteristics of Mathematical Creativity

    ERIC Educational Resources Information Center

    Sriraman, Bharath

    2004-01-01

    Mathematical creativity ensures the growth of mathematics as a whole. However, the source of this growth, the creativity of the mathematician, is a relatively unexplored area in mathematics and mathematics education. In order to investigate how mathematicians create mathematics, a qualitative study involving five creative mathematicians was…

  10. Remedial Mathematics for Quantum Chemistry

    ERIC Educational Resources Information Center

    Koopman, Lodewijk; Brouwer, Natasa; Heck, Andre; Buma, Wybren Jan

    2008-01-01

    Proper mathematical skills are important for every science course and mathematics-intensive chemistry courses rely on a sound mathematical pre-knowledge. In the first-year quantum chemistry course at this university, it was noticed that many students lack basic mathematical knowledge. To tackle the mathematics problem, a remedial mathematics…

  11. Remedial Mathematics for Quantum Chemistry

    ERIC Educational Resources Information Center

    Koopman, Lodewijk; Brouwer, Natasa; Heck, Andre; Buma, Wybren Jan

    2008-01-01

    Proper mathematical skills are important for every science course and mathematics-intensive chemistry courses rely on a sound mathematical pre-knowledge. In the first-year quantum chemistry course at this university, it was noticed that many students lack basic mathematical knowledge. To tackle the mathematics problem, a remedial mathematics…

  12. Astronomy and Mathematics Education

    NASA Astrophysics Data System (ADS)

    Ros, Rosa M.

    There are many European countries where Astronomy does not appear as a specific course on the secondary school. In these cases Astronomy content can be introduced by means of other subjects. There are some astronomical topics within the subject of Physics but this talk concerns introducing Astronomy in Mathematics classes. Teaching Astronomy through Mathematics would result in more exposure than through Physics as Mathematics is more prevalent in the curriculum. Generally it is not easy to motivate students in Mathematics but they are motivated to find out more about the universe and Astronomy current events than appears in the media. This situation can be an excellent introduction to several mathematics topics. The teachers in secondary and high school can use this idea in order to present more attractive mathematics courses. In particular some different examples will be offered regarding * Angles and spherical coordinates considering star traces * Logarithms and visual magnitudes * Plane trigonometry related orbital movements * Spherical trigonometry in connection with ecliptic obliquity * Conic curves related to sundial at several latitudes Some students do not enjoy studying Mathematics but they can be attracted by practical situations using Applied Mathematics: Astronomy is always very attractive to teenagers.

  13. Business Mathematics Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    This curriculum guide for teaching business mathematics in the Connecticut Vocational-Technical School System is based on the latest thinking of instructors in the field, suggestions from mathematics authorities, and current instructional approaches in education. The curriculum guide consists of six sections: (1) career relationships and…

  14. Developing Mathematical Proficiency

    ERIC Educational Resources Information Center

    Groves, Susie

    2012-01-01

    It has long been recognised that successful mathematical learning comprises much more than just knowledge of skills and procedures. For example, Skemp (1976) identified the advantages of teaching mathematics for what he referred to as "relational" rather than "instrumental" understanding. More recently, Kilpatrick, Swafford and…

  15. Business Mathematics Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    This curriculum guide for teaching business mathematics in the Connecticut Vocational-Technical School System is based on the latest thinking of instructors in the field, suggestions from mathematics authorities, and current instructional approaches in education. The curriculum guide consists of six sections: (1) career relationships and…

  16. Quality Teaching in Mathematics

    ERIC Educational Resources Information Center

    Ediger, Marlow

    2012-01-01

    The best teaching possible needs to accrue in the mathematics curriculum. Pupils also need to become proficient in using mathematics in every day situations in life. Individuals buy goods and services. They pay for these in different ways, including cash. Here, persons need to be able to compute the total cost of items purchased and then pay for…

  17. Quality Teaching in Mathematics

    ERIC Educational Resources Information Center

    Ediger, Marlow

    2012-01-01

    The best teaching possible needs to accrue in the mathematics curriculum. Pupils also need to become proficient in using mathematics in every day situations in life. Individuals buy goods and services. They pay for these in different ways, including cash. Here, persons need to be able to compute the total cost of items purchased and then pay for…

  18. Elementary Mathematics Leaders

    ERIC Educational Resources Information Center

    Fennell, Francis; Kobett, Beth McCord; Wray, Jonathan A.

    2013-01-01

    Elementary school mathematics leaders often come to the realization that their position, however titled and determined, although dedicated to addressing needs in math teaching and learning, also entails and directly involves leadership. Elementary school math specialists/instructional leaders (referenced here as elementary mathematics leaders, or…

  19. Issues in Teaching Mathematics

    ERIC Educational Resources Information Center

    Ediger, Marlow

    2013-01-01

    In this article, the author states that there are selected issues in mathematics instruction that educators should be well aware of when planning lessons and units of study. These issues provide a basis for thought and discussion when assisting pupils to attain more optimally. Purposeful studying of issues guides mathematics teachers in…

  20. Designing Assessment for Mathematics

    ERIC Educational Resources Information Center

    Depka, Eileen

    2007-01-01

    Teaching mathematics in today's world requires practices and procedures integrated with performance tasks that actively involve students. In this second edition of Designing Rubrics for Mathematics, Eileen Depka clarifies the purpose of rubrics in math instruction and illustrates the relationship between assessment, rubrics, and the National…