Home  About us  Contact
 

Sample Application (sample + application)

Distribution by Scientific Domains
Mathematics and Statistics33%

Selected Abstracts

Flow Injection Analysis of Sulfide Using a Cinder/Tetracyano Nikelate Modified Screen-Printed Electrode

ELECTROANALYSIS, Issue 9 2005
Jyh-Myng Zen
Abstract Flow injection analysis (FIA) of sulfide is presented using a screen-printed carbon electrode modified with a cinder/tetracyano nickelate hybrid (designated as cinder/NiTcSPE). Hybridization of NiTc was achieved in iron-enriched industrial waste cinder material through the bimetallic formation of FeIII[NiII(CN)4]. The electrocatalytic oxidation of sulfide is mediated by the higher oxidation state of Ni in this hybrid-bimetallic complex. The system shows a detection limit (S/N=3) of 0.06,,M and a linear working range up to 1,mM in pH,10, 0.1,M KCl solution. Taking into account the relatively low volatility of the analyte in alkaline conditions, the system is ideally suited for the accurate detection of sulfide. The response of the electrode to sulfide is highly reproducible, thereby offering the potential development of a disposable amperometric sensor for sulfide. Selective detection of sulfide in cigarette smoke is presented in this study as an example of a real sample application. [source]

Quantitative evaluation of sample application methods for semipreparative separations of basic proteins by two-dimensional gel electrophoresis

ELECTROPHORESIS, Issue 19-20 2003
Richard C. Barry
Abstract The use of cup-loading for sample application has become widely used in two-dimensional electrophoresis (2-DE) for resolution of basic proteins, but no side-by-side quantitative study has been published which compares cup-loading with the alternative passive and active rehydration methods to fully promote one type of loading method over another. Replicate 2-D gels from each loading method were quantitatively evaluated for gel-to-gel reproducibility using IPG 6,11 strips and semipreparative protein loads (300 ,g). Gels were stained with SYPRO Ruby and analyzed with PDQuest. An inexpensive home-made assembly for cup-loading was used with the Protean IEF Cell for separation of whole cell extracts from the archaeon, Sulfolobus solfataricus. Cup-loading was determined to be far superior for IPG 6,11 separations than active or passive rehydration methods. Cup-loading consistently produced the greatest number of detectable spots, the best spot matching efficiency (56%), lowest spot quantity variations (28% coefficient of variation, CV), and the best-looking gels qualitatively. The least satisfactory results were obtained with active rehydration, followed closely by passive rehydration in off-line tubes. Passive rehydration experiments, performed using an on-line isoelectric focusing (IEF) tray, produced comparable spot numbers to cup-loading (84%), with 55% of the spots having higher intensity but 10% more spot quantity variance than cup-loading. [source]

Random dense bipartite graphs and directed graphs with specified degrees

RANDOM STRUCTURES AND ALGORITHMS, Issue 2 2009
Catherine Greenhill
Abstract Let s and t be vectors of positive integers with the same sum. We study the uniform distribution on the space of simple bipartite graphs with degree sequence s in one part and t in the other; equivalently, binary matrices with row sums s and column sums t. In particular, we find precise formulae for the probabilities that a given bipartite graph is edge-disjoint from, a subgraph of, or an induced subgraph of a random graph in the class. We also give similar formulae for the uniform distribution on the set of simple directed graphs with out-degrees s and in-degrees t. In each case, the graphs or digraphs are required to be sufficiently dense, with the degrees varying within certain limits, and the subgraphs are required to be sufficiently sparse. Previous results were restricted to spaces of sparse graphs. Our theorems are based on an enumeration of bipartite graphs avoiding a given set of edges, proved by multidimensional complex integration. As a sample application, we determine the expected permanent of a random binary matrix with row sums s and column sums t. © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009 [source]

A physical, mechanistic and fully coupled hillslope hydrology model

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2005
David A. Raff
Abstract We present the mathematical development and numerical solution of a new model of flow processes on an infiltrating hillslope. We also present validation and sample applications. The model is a distributed, mechanistic, physically based hillslope hydrologic model. The model describes the small-scale processes associated with overland flow, erosion, and sediment transport on an infiltrating surface and is capable of capturing small-scale variations in flow depth, flow velocities, interactive infiltration, erosion rates, and sediment transport. The model couples the fully two-dimensional hydrodynamic equations for overland flow, the one-dimensional Richards equation for infiltration, and a sediment detachment and transport model. Two simulations are presented highlighting the model's ability to capture and describe the interaction between precipitation, overland flow, erosion and infiltration at very small scales. Results of the two-dimensional simulations indicate the system of equations produces hillslopes possessing characteristics of self-organization as observed in real world systems. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Computation and presentation of graphs displaying closure hierarchies of Jordan and Kronecker structures

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 6-7 2001
Erik Elmroth
Abstract StratiGraph, a Java-based tool for computation and presentation of closure hierarchies of Jordan and Kronecker structures is presented. The tool is based on recent theoretical results on stratifications of orbits and bundles of matrices and matrix pencils. A stratification reveals the complete hierarchy of nearby structures, information critical for explaining the qualitative behaviour of linear systems under perturbations. StratiGraph facilitates the application of these theories and visualizes the resulting hierarchy as a graph. Nodes in the graph represent orbits or bundles of matrices or matrix pencils. Edges represent covering relations in the closure hierarchy. Given a Jordan or Kronecker structure, a user can obtain the complete information of nearby structures simply by mouse clicks on nodes of interest. This contribution gives an overview of the StratiGraph tool, presents its main functionalities and other features, and illustrates its use by sample applications. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Lactobionic acid in a natural alkylpolyglucoside-based vehicle: assessing safety and efficacy aspects in comparison to glycolic acid

JOURNAL OF COSMETIC DERMATOLOGY, Issue 1 2010
Marija Tasic-Kostov BSc
Summary Background/aims, Lactobionic acid (LA) is a newer cosmeceutical active belonging to the class of alpha-hydroxyacids (AHAs), showing advantages over them. The aim of part I of this study was to compare efficacy and irritation potential of LA vs. glycolic acid (GA) from two types of vehicles , gel and emulsion. In part II, effects of LA-containing emulsions based on a new, natural emulsifier of alkylpolyglucoside (APG) type were evaluated. Methods, Skin bioengineering was used on 77 healthy volunteers to assess: color as erythema and melanin (MI) index, transepidermal water loss, electrical capacitance and pH of the skin. In part I of the study, the parameters were measured after occlusion and periodically during 2 weeks of test samples application; in part II parameters were measured periodically during 4 weeks. Results/conclusion, LA-containing samples has produced better skin performance when compared with corresponding GA-containing ones, particularly the lack of both skin irritation and skin barrier impairment. When used in vehicles based on a new APG-emulsifier, LA and GA have shown better efficacy, emphasizing the importance of vehicle on the effects of topical actives. LA (6%) in the emulsion based on APGs could be proposed as an alternative to low-molecular AHAs in cosmeceuticals. [source]