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Modification Procedure (modification + procedure)

Distribution by Scientific Domains
Chemistry33%

Selected Abstracts

Study of Factors Affecting the Performance of Voltammetric Copper Sensors Based on Gly-Gly-His Modified Glassy Carbon and Gold Electrodes

ELECTROANALYSIS, Issue 12 2006
Guozhen Liu
Abstract This paper reports a study of the factors affecting the analytical performance of gold and glassy carbon electrodes modified with the tripeptide Gly-Gly-His for the detection of copper ions. Gly-Gly-His is attached to a glassy carbon (GC) surface modified with 4-carboxyphenyl moieties or a gold surface modified with 3-mercaptopropionic acid by the reaction of the N-terminal amine group of the peptide with the carboxylic acid groups of the monolayer via carbodiimide activation. X-ray photoelectron spectroscopy was used to characterize the steps in the biosensor fabrication. It was found that the analytical performance of a sensor prepared with Gly-Gly-His on a GC electrode was similar to that on a gold electrode under the same conditions. The performance was greatly enhanced at higher temperature, no added salt during copper accumulation and longer accumulation time within a pH range of 7,9. Interference studies and investigations of stability of the Gly-Gly-His sensor are reported. Analysis of natural water samples show that the sensors measure only copper ions that can complex at the sensor surface. Strongly complexed copper in natural water is not measured. Despite greater stability of diazonium salt derived monolayers on carbon surfaces compared with alkanethiols self-assembled monolayers on gold, the stability of the sensors was essentially the same regardless of the modification procedure. [source]

High-performance separation of small inorganic anions on a methacrylate-based polymer monolith grafted with [2(methacryloyloxy)ethyl] trimethylammonium chloride

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009
Damian Connolly
Abstract A glycidyl methacrylate- co -ethylene dimethacrylate monolith in capillary format (100 ,m/id) has been grafted with chains of poly([2(methacryloyloxy)ethyl] trimethylammonium chloride (poly-META) and applied to the ion-chromatographic separation of selected inorganic anions. Grafting chains of META onto the generic monolithic scaffold resulted in a monolith with ,electrolyte responsive flow permeability', which manifested as increased permeability in the presence of electrolyte solutions. Using an eluent of 2 mM sodium benzoate and on-column contactless conductivity detection, a test mixture of six common anions was isocratically separated and detected within 12 min, with the first four anions baseline resolved within a retention time window of 3.2 min. Retention time precision was ,1.2% for all anions tested. Separation efficiencies of 15 000 N/m were achieved for fluoride at 1 ,L/min, with column efficiencies up to 29 500 N/m obtained at a lower flow rate of 100 nL/min. Furthermore, repeatability of the column modification procedure using photografting methods was acceptable, with retention times between replicate columns matching within 9%. [source]

Joint attention training for children with autism using behavior modification procedures

THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 3 2003
Christina Whalen
Background: Deficits in joint attention are considered by many researchers to be an early predictor of childhood autism (e.g., Osterling & Dawson, 1994) and are considered to be pivotal to deficits in language, play, and social development in this population (Mundy, 1995). Although many researchers have noted the importance of joint attention deficits in the development of children with autism (e.g., Mundy, Sigman, & Kasari, 1994) and have called for intervention strategies (e.g., Mundy & Crowson, 1997), few studies have attempted to target joint attention. In this study, joint attention behaviors were taught to children with autism using a behavior modification procedure. Methods: A multiple-baseline design was implemented to evaluate intervention effects. The following target behaviors were included in the intervention: 1) Responding to showing, pointing, and gaze shifting of adult; 2) Coordinated gaze shifting (i.e., coordinated joint attention); and 3) Pointing (with the purpose of sharing, not requesting). Generalization to setting and parent, follow-up sessions, and social validation measures were also analyzed. Results: Joint attention behaviors were effectively trained and targeted behaviors generalized to other settings. In addition, positive changes were noted by naïve observers using social validation measures. Conclusions: Integrating joint attention training into existing interventions may be important for children with autism. In addition, training parents in these techniques may help to maintain joint attention skills outside of the treatment setting. [source]

Anisotropic adaptive simulation of transient flows using discontinuous Galerkin methods

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2005
Jean-François Remacle
Abstract An anisotropic adaptive analysis procedure based on a discontinuous Galerkin finite element discretization and local mesh modification of simplex elements is presented. The procedure is applied to transient two- and three-dimensional problems governed by Euler's equation. A smoothness indicator is used to isolate jump features where an aligned mesh metric field in specified. The mesh metric field in smooth portions of the domain is controlled by a Hessian matrix constructed using a variational procedure to calculate the second derivatives. The transient examples included demonstrate the ability of the mesh modification procedures to effectively track evolving interacting features of general shape as they move through a domain. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Functionalisation of Polyolefins: Grafting of Phenol Groups on Olefin/5,7-Dimethylocta-1,6-diene Copolymers

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2003
Marc Dolatkhani
Abstract The grafting of phenol groups on ethylene/5,7-dimethylocta-1,6-diene copolymers and on ethylene/propylene/5,7-dimethylocta-1,6-diene terpolymers was performed, using two different modification procedures. An indirect route involving hydrochlorination followed by phenol insertion was found to be very effective for the terpolymers, and lead to a grafting phenol rate higher than 75%. However, if the phenol grafting is performed directly on a non-modified terpolymer, lower rates are obtained. When applied to the copolymers the procedures used were revealed to be less efficient. This fact might be related to the lower solubility of the ethylene/5,7-dimethylocta-1,6-diene copolymers (related to a higher crystallinity and a smaller diene content) when compared with the corresponding terpolymers. Although incomplete, the addition of a hindered phenol to the copolymer gave rise to a polymer that, when compared to polyethylene, presents a higher thermal-oxidative stability. Grafting of phenol on a hydrochlorinated ethylene/propylene/5,7-DMO terpolymer. [source]

Joint attention training for children with autism using behavior modification procedures

THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 3 2003
Christina Whalen
Background: Deficits in joint attention are considered by many researchers to be an early predictor of childhood autism (e.g., Osterling & Dawson, 1994) and are considered to be pivotal to deficits in language, play, and social development in this population (Mundy, 1995). Although many researchers have noted the importance of joint attention deficits in the development of children with autism (e.g., Mundy, Sigman, & Kasari, 1994) and have called for intervention strategies (e.g., Mundy & Crowson, 1997), few studies have attempted to target joint attention. In this study, joint attention behaviors were taught to children with autism using a behavior modification procedure. Methods: A multiple-baseline design was implemented to evaluate intervention effects. The following target behaviors were included in the intervention: 1) Responding to showing, pointing, and gaze shifting of adult; 2) Coordinated gaze shifting (i.e., coordinated joint attention); and 3) Pointing (with the purpose of sharing, not requesting). Generalization to setting and parent, follow-up sessions, and social validation measures were also analyzed. Results: Joint attention behaviors were effectively trained and targeted behaviors generalized to other settings. In addition, positive changes were noted by naïve observers using social validation measures. Conclusions: Integrating joint attention training into existing interventions may be important for children with autism. In addition, training parents in these techniques may help to maintain joint attention skills outside of the treatment setting. [source]