EVOLUTION, Issue 5 2009
Reinmar Hager
Epigenetic effects attributed to genomic imprinting are increasingly recognized as an important source of variation in quantitative traits. However, little is known about their relative contribution to phenotypic variation compared to those of additive and dominance effects, and almost nothing about their role in phenotypic evolution. Here we address these questions by investigating the relative contribution of additive, dominance, and imprinting effects of quantitative trait loci (QTL) to variation in "early" and "late" body weight in an intercross of mice selected for divergent adult body weight. We identified 18 loci on 13 chromosomes; additive effects accounted for most of the phenotypic variation throughout development, and imprinting effects were always small. Genetic effects on early weight showed more dominance, less additive, and, surprisingly, less imprinting variation than that of late weight. The predominance of additivity of QTL effects on body weight follows the expectation that additive effects account for the evolutionary divergence between selection lines. We hypothesize that the appearance of more imprinting effects on late body weight may be a consequence of divergent selection on adult body weight, which may have indirectly selected for alleles showing partial imprinting effects due to their associated additive effects, highlighting a potential role of genomic imprinting in the response to selection. [source]

THE EFFECT OF EPISTASIS ON THE EXCESS OF THE ADDITIVE AND NONADDITIVE VARIANCES AFTER POPULATION BOTTLENECKS

EVOLUTION, Issue 5 2002
Carlos López-Fanjul
Abstract The effect of population bottlenecks on the components of the genetic variance generated by two neutral independent epistatic loci has been studied theoretically (VA, additive; VD, dominant; VAA, additive × additive; VAD, additive × dominant; VDD; dominant × dominant components of variance). Nonoverdominance and overdominance models were considered, covering all possible types of marginal gene action at the single locus level. The variance components in an infinitely large panmictic population (ancestral components) were compared with their expected values at equilibrium, after t consecutive bottlenecks of equal size N (derived components). Formulae were obtained in terms of allele frequencies and effects at each locus and the corresponding epistatic value. An excess of VA after bottlenecks can be assigned to two sources: (1) the spatiotemporal changes in the marginal average effects of gene substitution ai, which are equal to zero only for additive gene action within and between loci; and (2) the covariance between a2i and the heterozygosity at the loci involved, which is generated by dominance, with or without epistasis. Numerical examples were analyzed, indicating that an increase in VA after bottlenecks will only occur if its ancestral value is minimal or very small. For the nonoverdominance model with weak reinforcing epistasis, that increase has been detected only for extreme frequencies of the negative allele at one or both loci. With strong epistasis, however, this result can be extended to a broad range of intermediate frequencies. With no epistasis, the same qualitative results were found, indicating that dominance can be considered as the primary cause of an increase in VA following bottlenecks. In parallel, the derived total nonadditive variance exceeded its ancestral value (VNA= VD+ VAA+VAD+ VDD) for a range of combinations of allele frequencies covering those for an excess of VA and for very large frequencies of the negative allele at both loci. For the overdominance model, an increase in VA and VNA was respectively observed for equilibrium (intermediate) frequencies at one or both loci or for extreme frequencies at both loci. For all models, the magnitude of the change of VA and VNA was inversely related to N and t. At low levels of inbreeding, the between-line variance was not affected by the type of gene action. For the models considered, the results indicate that it is unlikely that the rate of evolution may be accelerated after population bottlenecks, in spite of occasional increments of the derived VA over its ancestral value. [source]

EFFECT OF PRETREATMENTS AND ADDITIVES ON THE THERMAL BEHAVIOR AND HYGROSCOPICITY OF FREEZE-DRIED PINEAPPLE JUICE POWDER

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5-6 2005
H.S. PHANINDRAKUMAR
ABSTRACT Pasteurization of pineapple juices at 80C for 5 min in the presence of added acids (citric, malic and fumaric) and cane sugar was found to increase its reducing sugar content from 3.5 to 6.5%, which in turn decreased the glass transition temperature (Tg) and increased the hygroscopicity of the juice powder. Inversion of sucrose could be avoided by adding sugar and acid to a pasteurized cooled juice. Among the acids, citric acid caused 30% more hygroscopicity than malic and fumaric. Incorporation of additives into the juice prior to freeze-drying helped in reducing the hygroscopic tendency of the juice powder. Among the additives tried, trehalose, beta-cyclodextrin and sorbitol were found to be beneficial as they increase the Tg and reduce the hygroscopic tendency of the juice powder. [source]

PHYSICAL PROPERTIES OF FISH PROTEINS COOKED WITH STARCHES OR PROTEIN ADDITIVES UNDER OHMIC HEATING

JOURNAL OF FOOD QUALITY, Issue 5 2007
PANIDA PONGVIRAT CHAI
ABSTRACT The texture, color and microstructure of surimi seafood gels were investigated to determine the interaction effects of fish proteins with starches or protein additives under ohmic heating, and to compare ohmically cooked gels with conventional water-bath-cooked gels. Gel properties were affected by the type of additive, concentration and cooking method. The effect of starch on gel texture was more pronounced at low concentrations. Compared to wheat starch, potato starch seemed to slightly improve gel strength; however, it decreased the gel whiteness. All nonfish protein additives resulted in better or equal textural properties of gels, whereas there was a slightly negative effect for gel color. Fast ohmic-cooked gels mostly exhibited higher gel strength than conventionally cooked gels. PRACTICAL APPLICATIONS There is a discrepancy between current gel preparation (slow heating by water bath) and current practice of crabstick manufacturing (fast heating). The use of data generated from slow cooking gel preparation for the manufacture of fast cooking crabstick does not make sense. This study demonstrates how starch and protein additives behave at ohmic heating which mimics the fast cooking crabstick manufacture. [source]

Phenylphosphoric Acid as a New Additive to Inhibit Olefin Isomerisation in Ruthenium-Catalysed Metathesis Reactions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2007
Nélida Gimeno
Abstract A systematic study of the ruthenium-catalysed metathesis of alkenes containing hydrogen-bonding substituents (namely urea and thiourea groups) is presented. Under standard metathesis conditions, several of the substrates under study undergo alkene isomerisation instead of the targeted metathesis. However, in the course of these investigations it has been established that this unwanted isomerisation process can be suppressed by addition of phenylphosphoric acid to the reaction mixture. Some other potential isomerisation inhibitors (e.g. benzoic acid and salts of phosphoric acid) have been studied and their performance compared to that of phenylphosphoric acid. To extend the scope of phenylphosphoric acid, we also studied the metathesis of 1,3-diallylurea. Interestingly, not only did we observe the complete suppression of the isomerisation process, but also that it is possible to obtain instead of the ring-closing metathesis (RCM) product,ADMET oligomers resulting from the cross-metathesis of diallylurea at higher concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Combining adenoviral oncolysis with temozolomide improves cell killing of melanoma cells

INTERNATIONAL JOURNAL OF CANCER, Issue 12 2007
Christina Quirin
Abstract Oncolytic Adenoviruses are emerging agents for treatment of cancer by tumor-restricted virus replication, cell lysis and virus spread. Clinical studies with first generation oncolytic adenoviruses have revealed that an increased potency is warranted in order to achieve therapeutic efficacy. One approach towards this end is to combine adenoviral oncolysis with chemotherapy. Here, a fundamental requirement is that chemotherapy does not interfere with adenovirus replication in cancer cells. We have previously developed a melanoma-targeted oncolytic adenovirus, Ad5/3.2xTyr, which features tyrosinase promoter regulated replication and enhanced cell entry into melanoma cells. In this study, we investigated a combination treatment of melanoma cells with Ad5/3.2xTyr and temozolomide (TMZ), which produces the same active metabolite as Dacarbazine/DTIC, the standard chemotherapy for advanced melanoma. We report that TMZ does not inhibit adenovirus replication in melanoma cells. Additive or synergistic cell killing of melanoma cells, dependent on the cell line used, was observed. Enhanced cell binding was not responsible for synergism of adenoviral oncolysis and TMZ treatment. We rather observed that higher numbers of virus genomes are produced in TMZ-treated cells, which also showed a cell cycle arrest in the G2 phase. Our results have important implications for the clinical implementation of adenoviral oncolysis for treatment of malignant melanoma. It suggests that such studies are feasible in the presence of TMZ or DTIC chemotherapy and recommends the investigation of a viro-chemo combination therapy. © 2007 Wiley-Liss, Inc. [source]

Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction Conditions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009
Jeanne
No abstract is available for this article. [source]

Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction Conditions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009
Jeanne
Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source]

Linkage and QTL mapping for Sus scrofa chromosome 11

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2003
M. Dragos-Wendrich
Summary Linkage and QTL maps of Sus scrofa chromosome 11 (SSC11) have been produced based on four microsatellite markers genotyped in three F2 families from Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The maps were similar across the families and in agreement with already published maps. Quantitative Trait Loci (QTLs) were identified in the W × M family and not in the M × P and W × P families. The QTLs affected live weight, loin and neck meat weight, back-fat depth and food consumption, and explained up to 4.7% of the F2 phenotypic variance. Additive and dominance effects were similar in size. The Wild Boar QTL alleles led to higher trait values in comparison with Meishan alleles. Zusammenfassung Kopplungskarten für Chromosom 11 (SSC11), die durch Analyse von vier Mikrosatelliten-Markern in drei F2 -Familien aus Kreuzungen von Wildschwein (W), Meishan (M) und Pietrain (P) erstellt wurden, zeigten eine gute Übereinstimmung zwischen den Familien sowie mit Literaturergebnissen. Quantitative Trait Loci (QTLs) waren in der Familie W × M nachzuweisen, jedoch nicht in den Familien M × P und W × P. Sie beeinflussten Lebendgewicht, Kotelettstranggewicht, Rückenspeckdicke und Futteraufnahme und erklärten bis zu 4,7% der phänotypischen Varianz in der F2 -Generation. Additiv- und Dominanzeffekte waren ähnlich groß. Wildschwein-QTL-Allele führten im Vergleich zu Meishan-Allelen zu höheren Merkmalswerten. [source]

Densification of Si3N4 with LiYO2 Additive

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2004
Branko Matovic
This paper deals with the densification and phase transformation during pressureless sintering of Si3N4 with LiYO2 as the sintering additive. The dilatometric shrinkage data show that the first Li2O- rich liquid forms as low as 1250°C, resulting in a significant reduction of sintering temperature. On sintering at 1500°C the bulk density increases to more than 90% of the theoretical density with only minor phase transformation from ,-Si3N4 to ,-Si3N4 taking place. At 1600°C the secondary phase has been completely converted into a glassy phase and total conversion of ,-Si3N4 to ,-Si3N4 takes place. The grain growth is anisotropic, leading to a microstructure which has potential for enhanced fracture toughness. Li2O evaporates during sintering. Thus, the liquid phase is transient and the final material might have promising mechanical properties as well as promising high-temperature properties despite the low sintering temperature. The results show that the Li2O,Y2O3 system can provide very effective low-temperature sintering additives for silicon nitride. [source]

Role of Vanadium Carbide Additive during Sintering of WC,Co: Mechanism of Grain Growth Inhibition

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2003
Hyoung R. Lee
In a WC,Co specimen, the shape of WC crystals was a triangular prism with truncated corners. When VC was added to inhibit grain growth, the crystal shape changed to a triangular prism without truncation. This shape change was related to the variation of edge energy, which has a significant influence on the coarsening process of WC grains. [source]

Sintering of AlN Using CaO-Al2O3 as a Sintering Additive: Chemistry and Microstructural Development

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2002
Eirik Hagen
The densification of aluminum nitride using Ca12Al14O33 as a sintering aid has been studied with emphasis on the effect of using coarse or fine powder, the amount of sintering aid, the sintering temperature, and embedding. Both crystalline and amorphous grain boundary phases were observed. Significant weight losses were observed for coarse-grained samples, and if suitable embedding was not used. Porous and coarse-grained ceramics with high contiguity and minor amounts of secondary phases were obtained by enhanced evaporation while dense ceramics were obtained limiting the evaporation. High weight losses in the graphite environment resulted in formation of a dense AlN surface layer. [source]

Causal inference with generalized structural mean models

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 4 2003
S. Vansteelandt
Summary., We estimate cause,effect relationships in empirical research where exposures are not completely controlled, as in observational studies or with patient non-compliance and self-selected treatment switches in randomized clinical trials. Additive and multiplicative structural mean models have proved useful for this but suffer from the classical limitations of linear and log-linear models when accommodating binary data. We propose the generalized structural mean model to overcome these limitations. This is a semiparametric two-stage model which extends the structural mean model to handle non-linear average exposure effects. The first-stage structural model describes the causal effect of received exposure by contrasting the means of observed and potential exposure-free outcomes in exposed subsets of the population. For identification of the structural parameters, a second stage ,nuisance' model is introduced. This takes the form of a classical association model for expected outcomes given observed exposure. Under the model, we derive estimating equations which yield consistent, asymptotically normal and efficient estimators of the structural effects. We examine their robustness to model misspecification and construct robust estimators in the absence of any exposure effect. The double-logistic structural mean model is developed in more detail to estimate the effect of observed exposure on the success of treatment in a randomized controlled blood pressure reduction trial with self-selected non-compliance. [source]

Effect of genome composition and cytoplasm on petal colour in resynthesized amphidiploids and sesquidiploids derived from crosses between Brassica rapa and Brassica oleracea

PLANT BREEDING, Issue 4 2002
B. Zhang
Abstract The effect of genome composition and cytoplasm on petal colour was studied in Brassica. Three accessions of yellow-petalled B. rapa (2n= 20, AA) were crossed with a white-petalled B. oleracea var. alboglabra (2n= 18, CC) and with three cream-yellow-petalled B. oleracea var. gongylodes (2n= 18, CC) to produce resynthesized B. napus (2n= 38, AACC or CCAA) and sesquidiploids (2n= 29, AAC or CAA). Petal colour was measured with a Hunter automatic colour difference meter. The results revealed that petal colour in Brassica is controlled by nuclear genes and by cytoplasmic factors. Additive and epistatic gene effects were involved in the action of nuclear genes. When crosses were made between yellow-petalled B. rapa and white-petalled B. oleracea var. alboglabra, significant additive, epistatic and cytoplasmic effects were found. White petal colour was partially epistatic over yellow petal colour. When crosses were made between yellow-petalled B. rapa and cream-yellow-petalled B. oleracea var. gongylodes, only epistatic effects were detected. Yellow petal colour was epistatic over cream-yellow. [source]

Additive preconditioning in matrix computations

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2007
V. Y. Pan
We combine our novel SVD-free additive preconditioning with aggregation and other relevant techniques to facilitate the solution of a linear system of equations and other fundamental matrix computations. Our analysis and experiments show the power of our algorithms, guide us in selecting most effective policies of preconditioning and aggregation, and provide some new insights into these and related subjects. Compared to the popular SVD-based multiplicative preconditioners, our additive preconditioners are generated more readily and for a much larger class of matrices. Furthermore, they better preserve matrix structure and sparseness and have a wider range of applications (e.g., they facilitate the solution of a consistent singular linear system of equations and of the eigen-problem). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Metal,Fluorocarbon Pyrolants: X., Influence of Ferric Oxide/Silicon Additive on Burn Rate and Radiometric Performance of Magnesium/Teflon/Viton® (MTV)

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2009
Ernst-Christian Koch
Abstract Both burn rate, u (mm s,1) and mass consumption rate, (g s,1 cm,2) of fuel rich magnesium/Teflon/Viton® (MTV) (45/50/5) upon addition of silicon/ferric oxide for part of the PTFE decrease by 16 and 11%, respectively. However, the spectral efficiency E, (J g,1 sr,1) increases by 24% in the 3,5,,m band. [source]

Additive, dominance genetic effects for growth-related traits in common carp, Cyprinus carpio L.

AQUACULTURE RESEARCH, Issue 14 2006
Cheng-Hui Wang
Abstract Additive, dominance genetic effects were analysed for body weight (BW) and seven morphometric traits from three variants of red common carp, Cyprinus carpio var. singuonensis, C. carpio var. wuyuanensis and C. carpio var. color, based on a diallel cross-mating design by using the additive,dominance genetic model. The results indicated that at 8 months of age (juvenile stage), the traits of pre-dorsal height (PDH), pre-dorsal width (PDW) and caudal peduncle height (CPH) were mainly controlled by additive effects; the traits of BW, total length (TL), standard length (SL), head length (HL) and caudal peduncle length (CPL) were mainly controlled by dominance effects. The narrow-sense heritabilities of all traits ranged from 0.000 to 0.556; however, the broad-sense heritabilities ranged from 0.453 to 0.775. At 20 months of age (adult stage), the traits of TL, SL, PDH and CPL were mainly controlled by additive effects, whereas the traits of BW, PDW, HL and CPH were mainly controlled by dominance effects. The narrow-sense heritabilities of all traits ranged from 0.000 to 0.710; the broad-sense heritabilities ranged from 0.629 to 0.934. Through the genetic merit prediction from three parents, it was found that the additive and dominance effects of C. carpio var. color could increase the BW and body length in their progeny, but these two genetic effects of C. carpio var. singuonensis and C. carpio var. wuyuanensis could decrease BW in their progeny. The genetic effects of C. carpio var. wuyuanensis could reduce total length, SL and caudal peduncle length, but increase body height in their progeny. [source]

Hierarchical Spatial Modeling of Additive and Dominance Genetic Variance for Large Spatial Trial Datasets

BIOMETRICS, Issue 2 2009
Andrew O. Finley
Summary This article expands upon recent interest in Bayesian hierarchical models in quantitative genetics by developing spatial process models for inference on additive and dominance genetic variance within the context of large spatially referenced trial datasets. Direct application of such models to large spatial datasets are, however, computationally infeasible because of cubic-order matrix algorithms involved in estimation. The situation is even worse in Markov chain Monte Carlo (MCMC) contexts where such computations are performed for several iterations. Here, we discuss approaches that help obviate these hurdles without sacrificing the richness in modeling. For genetic effects, we demonstrate how an initial spectral decomposition of the relationship matrices negate the expensive matrix inversions required in previously proposed MCMC methods. For spatial effects, we outline two approaches for circumventing the prohibitively expensive matrix decompositions: the first leverages analytical results from Ornstein,Uhlenbeck processes that yield computationally efficient tridiagonal structures, whereas the second derives a modified predictive process model from the original model by projecting its realizations to a lower-dimensional subspace, thereby reducing the computational burden. We illustrate the proposed methods using a synthetic dataset with additive, dominance, genetic effects and anisotropic spatial residuals, and a large dataset from a Scots pine (Pinus sylvestris L.) progeny study conducted in northern Sweden. Our approaches enable us to provide a comprehensive analysis of this large trial, which amply demonstrates that, in addition to violating basic assumptions of the linear model, ignoring spatial effects can result in downwardly biased measures of heritability. [source]

Palladium-Catalyzed Cross-Coupling of 2-Haloselenophene with Terminal Alkynes in the Absence of Additive.

CHEMINFORM, Issue 28 2006
Olga Soares do Rego Barros
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Enantioselective Aza-Diels,Alder Reaction Catalyzed by a Chiral Broensted Acid: Effect of the Additive on the Enantioselectivity.

CHEMINFORM, Issue 21 2006
Takahiko Akiyama
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2, Part II: Catalytic Activities and Mechanism

CHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2006
Man Kin Tse Dr.
Abstract Asymmetric epoxidation of olefins with 30,% H2O2 in the presence of [Ru(pybox)(pydic)] 1 and [Ru(pyboxazine)(pydic)] 2 has been studied in detail (pybox=pyridine-2,6-bisoxazoline, pyboxazine=pyridine-2,6-bisoxazine, pydic=2,6-pyridinedicarboxylate). 35 Ruthenium complexes with sterically and electronically different substituents have been tested in environmentally benign epoxidation reactions. Mono-, 1,1-di-, cis - and trans -1,2-di-, tri-, and tetra-substituted aromatic olefins with versatile functional groups can be epoxidized with this type of catalyst in good to excellent yields (up to 100,%) with moderate to good enantioselectivies (up to 84,% ee). Additive and solvent effects as well as the relative rate of reaction with different catalysts have been established. It is shown that the presence of weak organic acids or an electron-withdrawing group on the catalyst increases the reactivity. New insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed epoxidation are proposed on the basis of density functional theory calculation and experiments. [source]

Lead(II) Potentiometric Sensor Based on 1,4,8,11-Tetrathiacyclotetradecane Neutral Carrier and Lipophilic Additives

ELECTROANALYSIS, Issue 11 2008
Mohamed
Abstract A potentiometric sensor for lead(II) ions based on the use of 1,4,8,11-tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis-(p -chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10,5,1.0×10,2,mol L,1 with a Nernstian slope of 29.9,mV decade,1 and a lower limit of detection of 2.2×10,6,mol L,1 Pb(II) ions over the pH range of 3,6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS. [source]

Determination of glyoxal and methylglyoxal in the serum of diabetic patients by MEKC using stilbenediamine as derivatizing reagent

ELECTROPHORESIS, Issue 21 2007
Muhammad A. Mirza
Abstract An analytical method has been developed for the separation of glyoxal (Go), methylglyoxal (MGo), and dimethylglyoxal (DMGo) by MEKC using stilbenediamine (SD) as derivatizing reagent, separation time 6.5,min, SDS as micellar medium at pH,8, and sodium tetraborate (0.1,M) as buffer. Uncoated fused-silica capillary, effective length 50,cm×75,,m id; applied voltage 20,kV and photodiode array detection, were used. Calibration was linear within 0.02,150,,g/mL with detection limits 3.5,5.8,ng/mL. Go and MGo, observed for diabetic and healthy volunteers, were within 0.098,0.193,,g/mL Go and 0.106,0.245,,g/mL MGo with RSD 1.6,3.5 and 1.7,3.4%, respectively, in diabetics against 0.016,0.046,,g/mL Go and 0.021,0.066,,g/mL MGo with RSDs 1.5,3.5 and 1.4,3.6%, respectively, in healthy volunteers. Go and MGo in diabetics were also measured by standard addition and DMGo as an internal standard. Additives do not contribute significantly to Go and MGo matrix. [source]

Organic Electronics: Improved Performance of Polymer Bulk Heterojunction Solar Cells Through the Reduction of Phase Separation via Solvent Additives (Adv. Mater.

ADVANCED MATERIALS, Issue 8 2010
8/2010)
The fabrication of bulk heterojunction organic solar cells from solution-casting techniques using low-cost materials makes them a promising new technology for converting sunlight into electricity. T.-Q. Nguyen, G. C. Bazan, et al. report on p. E63 that undesirable large-scale aggregation and phase separation that may arise during deposition can be reduced by incorporating a small amount of a well-chosen solvent additive. [source]

The Multiple Roles of Additives in CaCO3 Crystallization: A Quantitative Case Study

ADVANCED MATERIALS, Issue 4 2009
Denis Gebauer
To date, the knowledge of the multiple roles of additives in calcium carbonate crystallization results from empirical control of crystal growth. We present a crystallization assay generating controlled supersaturation, which allows the categorization of different modes of additive action. This facilitates a novel understanding of the action of crystallization additives. [source]

Essential Guide to Food Additives

INTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2006
Lesley Howie
No abstract is available for this article. [source]

An update of EU legislation (Directives and Regulations) on food-related issues (Safety, Hygiene, Packaging, Technology, GMOs, Additives, Radiation, Labelling): presentation and comments

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 10 2005
Ioannis S. Arvanitoyannis
Summary This review aims at providing an update of the current European Union (EU) Regulations and Directives on food-related issues. Initially, a brief presentation of EU legislation in terms of structure (horizontal, vertical) was attempted. EU Regulations and Directives were classified into the following categories: food safety (Hazard Analysis Critical Control Points, pesticides, radioactive, hormones, contaminants, freezing , ionisation, food additives, flavourings, packaging), genetically modified organisms, food quality, labelling, food products of plant or animal origin, imports from third countries. Apart from a synoptical presentation of all laws related to the above-mentioned topics, proper tables were compiled where the main points of each law are cited in conjunction with its effect on previous laws (repeal, modification, amendments, replacement). In such a way the reader can rapidly acquire a first approach to the topic of his interest. [source]

Food Additives: What every manager needs to know about the law

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2001
Jack Knights
No abstract is available for this article. [source]

Unprecedented Effects of Additives and Ligand-to-Metal Ratio on the Enantiofacial Selection of Copper-Catalyzed Alkynylation of ,-Imino Ester with Arylacetylenes

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010
Zhihui Shao
No abstract is available for this article. [source]

Preparation of Arylphosphonates by Palladium(0)-Catalyzed Cross-Coupling in the Presence of Acetate Additives: Synthetic and Mechanistic Studies

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009
Marcin Kalek
Abstract An efficient protocol for the synthesis of arylphosphonate diesters via a palladium-catalyzed cross-coupling of H-phosphonate diesters with aryl electrophiles, promoted by acetate ions, was developed. A significant shortening of the cross-coupling time in the presence of the added acetate ions was achieved for bidentate and monodentate supporting ligands, and for different aryl electrophiles (iodo, bromo and triflate derivatives). The reaction conditions were optimized in terms of amount of the catalyst, supporting ligands, and source of the acetate ion used. Various arylphosphonates, including those of potential biological significance, were synthesized using this newly developed protocol. Some mechanistic aspects of the investigated reactions are also discussed. [source]