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Resistance traits are economically important in crops in terms of accessibility to promising resistant germplasm. This study was conducted to evaluate SNP marker-trait association for Cereal Cyst Nematode (CCN), Heterodera filipjevi, in a large number of natural bread wheat populations. Phenotypic data analyzed using GLM (Generalized Linear Model) indicated significant differences among the landrace accessions for resistance to H. filipjevi. The genotyping was performed by 152K SNP chip on 188 accessions. After filtering, 10,471 polymorphic SNPs were employed for Genome Wide Association Study (GWAS). Population structure among the wheat genotypes were investigated using 840 well distinct SNP markers. Two sub-populations were revealed by structure software, and eleven markers were found to be significantly (P-value< 0.001) associated with resistance to H. filipjevi on chromosomes 2A, 3B, 4A, 4B, 5A, 5B, 5D, and 6B. The linkage disequilibrium analysis for all significantly associated SNPs showed that markers on chromosomes 4A and 4B were in high intra-chromosomal linkage disequilibrium, and, consequently, eight markers were recommended as strongly associated with resistance to H. filipjevi. The present study demonstrated valuable sources of resistance in the studied wheat genotypes against a widespread and important species of CCNs. The associated markers could be used in molecular breeding programs of bread wheat. [ABSTRACT FROM AUTHOR]

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Mesoporous silica nanoparticles (MSNs) have attracted a lot of notice as a platform in nanomaterials due to their specific properties such as large surface area, high pore size and volume, physical stability and uniform structures. The application of pure MSNs in various industries such as the petrochemical and pharmaceutical industries has been developed. The incorporation of metals into MSNs can increase the catalytic activity of MSNs due to their specific properties such as pore size and volume. Modification of MSNs by iron atoms (Fe-MSN) was studied in this research. The Fe-MSN was prepared using a sol–gel method. Here a comprehensive study was conducted on its enzyme mimicking and biocatalytic activities toward the oxidase, peroxidase and catalase enzymes. Hence, the relevant biocatalytic parameters were obtained through the reliable enzyme kinetic models. The results showed that Fe-MSN has high catalytic activity for decomposition of hydrogen peroxide (catalase activity) and for oxidation of aromatic hydrogen donors such as 3,3′,5,5′-tetramethylbenzidine (TMB). This activity can be carried out in the presence of oxygen as an oxidant (oxidase activity) and/or in the presence of a peroxide substrate, e.g. H2O2 (peroxidase activity) to produce the blue-colored product. Consequently, a colorimetric method was developed to determine H2O2 by Fe-MSN indicating a reasonable limit of detection (LOD) of 1.2 μM (3σ/slope) and a linear range over 7.2–100 μM. When Fe-MSN was coupled with glucose oxidase (a bienzymatic sequential detection system) glucose as a substrate can be detected at ≤1.2 μM over an experimental linear range of 4.1–100 μM. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major wheat disease that can inflict yield losses of up to 70% on susceptible varieties under favourable environmental conditions. The timely identification of plant genetic resources likely to possess novel resistance to this disease would facilitate the rapid development of resistant wheat varieties. The focused identification of germplasm strategy (FIGS) approach was used to predict stripe rust resistance in a collection of wheat landraces conserved at ICARDA genebank. Long-term climate data for the collection sites, from which these accessions originated and stripe rust evaluation scores for one group of accessions were presented to three different non-linear models to explore the trait×collection site environment interactions. Patterns in the data detected by the models were used to predict stripe rust resistance in a second and different set of accessions. The results of the prediction were then tested against actual evaluation scores of the disease in the field. The study mimics the real scenario where requests are made to plant genetic resources curators to provide accessions that are likely to possess variation for specific traits such as disease resistance.The models used were able to identify stripe rust-resistant accessions with a high degree of accuracy. Values as high as 0·75 for area under the curve and 0·45 for Kappa statistics, which quantify the agreement between the models’ predictions and the curator's disease scores, were achieved. This demonstrates a strong environmental component in the geographic distribution of resistance genes and therefore supports the theoretical basis for FIGS. It is argued that FIGS will improve the rate of gene discovery and efficiency of mining genetic resource collections for adaptive traits by reducing the number of accessions that are normally required for evaluation to identify such variation. [ABSTRACT FROM PUBLISHER]

Yellow (stripe) rust, caused by Puccinia striiformis f.sp. tritici (Pst), is a destructive disease of wheat (Triticum aestivum L.) all over the world, particularly in the Central and West Asia and North Africa (CWANA) region. Host plant resistance is the most economical and environment friendly approach to combating wheat rusts through the deployment of resistant cultivars. In this study, we report findings from an association mapping (AM) study of resistance to Pst in 167 facultative/winter elite wheat genotypes. The genotypes were evaluated for resistance to yellow rust (YR) at the adult plant stage and other agronomic traits for 2 yr (2011-2012) at ICARDA field station, Tel Hadya, Syria. The same genotypes were genotyped using 3051 diversity array technology (DArT) markers of which 1586 were of known chromosome positions. Out of the 167 genotypes evaluated for YR resistance, 65 genotypes (38.9%) were resistant, 20 genotypes (12%) were moderately resistant, 30 genotypes (18%) were moderately susceptible, and 52 genotypes (31.1%) were susceptible. Elite genotypes with high yield potential and YR resistance were identified and have been distributed to the National Agricultural Research System (NARS) for potential direct release and/or use as parents after local adaptation trials by the respective countries. Further, AM analysis using a mixed linear model (MLM), corrected for population structure and kinship relatedness and adjusted for false discovery rate (FDR), identified five genomic regions located on wheat chromosomes 2BL, 4BS, 6AS, 6BL, and 7BL which are significantly associated with genes conferring resistance to YR. The loci located on chromosome 4BS appeared to be a novel quantitative trait loci (QTL). These loci may be useful for choosing parents and incorporating new YR resistance genes into locally adapted wheat cultivars. [ABSTRACT FROM AUTHOR]

The kinetic and thermodynamic effects of three typical low-dosage imidazolium-based ionic liquids (ILs) on methane hydrate formation and dissociation were investigated, considering the anion nature and subcooling and/or overpressure driving forces. Isochoric hydrate formation and dissociation data were obtained by the modified slow step-heating method. ILs proved to have a dual effect on both formation and dissociation of methane hydrate including thermodynamic and kinetic inhibition. Kinetic modeling of methane hydrate inhibition by low-dosage ILs was performed. Kinetic analysis showed that IL inhibitors mainly cause a delay in the nucleation or hydrate growth step. The related inhibition mechanism was resolved regarding the ionic nature and electrostatic interactions of ILs with water molecules. Two binomial exponential kinetic relations were derived and used for simple methane hydrate formation in the presence of ILs as kinetic hydrate inhibitors. The proposed relations can serve for a quick estimation of the nature, extent, strength, and effectiveness of ILs on various gas hydrates. [ABSTRACT FROM AUTHOR]

Time-dependent isochoric formation of methane hydrate was investigated in the presence of low-dose poly(ethylene oxides) (PEOs). The effect of different molecular weights of PEO on methane hydrate nucleation time and storage capacity was studied and compared. Kinetic measurements revealed a dual effect of PEO, including inhibition and stabilization effects, on methane hydrate formation. The nature and type of the effect arises from the difference in molecular weights and concentration ranges of PEOs. These parameters directly affect the nucleation time and storage capacity of methane hydrate. Generally, in comparison with pure water, PEO improved the storage capacity of methane hydrate. PEO (1000 kD) at a concentration of 0.5 wt % exhibits a significant kinetic inhibitory performance. However, it was an efficient low-dosage hydrate stabilizer at a concentration of 0.25 wt %, along with producing gas-rich methane hydrate suitable for gas fuel storage and transportation. [ABSTRACT FROM AUTHOR]

Formation of a gas hydrate with two different gas compositions (natural gas and a mixture of methane-ethane-propane) was investigated using a special method of producing the hydrate from ice. Gas uptake, splitting the fraction of each component between the gas phase and hydrate phase, and purification of methane were studied in the presence of silica-based porous media. Addition of a small amount of colloidal silica media increased considerably the gas storage capacity of the hydrate phase. In the presence of silica-based porous media, the purification factor of CH4 became significantly higher. The results can provide the basis for the storage of natural gas in hydrate form and application of the hydrate-based gas separation technology to achieve methane with high purity from natural gas. [ABSTRACT FROM AUTHOR]

The new stem rust race Ug99 is an alarming threat to the wheat (Triticum aestivum L.) production of the world for the very fact that it overcomes many of the known Sr genes including the most commonly used genes such as 5r31, Sr24, and Sr36. The wheat breeding program at the International Center for Agricultural Research in the Dry Areas (ICARDA) has distributed the first stem rust resistant spring wheat yield trials composed of 24 wheat genotypes for the Central and West Asia and North Africa (CWANA) region to identify high yielding wheat genotypes, which can be recommended for direct release and/or parentage purposes by the National Agricultural Research Systems (NARS5). The additive main effects and multiplicative interaction (AMMI) analysis of variance for grain yield (kg ha-1) of 24 wheat genotypes tested in 15 environments showed that wheat grain yield was significantly (p <0.01) affected by environments (E), genotypes (G), and genotype x environment interaction (GEl). From the total sum of squares due to treatments (G + E + GEl), E contributed 90.1% and GEl accounted for 8.3% while G effect represented only 1.6%. According to AMMI2 estimate, Baasha-14 and Amir-2 with mean grain yield levels of 5168 and 5127 kg ha-1, respectively, are identified as the best genotypes with high yield potential across a wide range of environments. Based on correlation and clustering analysis among environments, the Ghab site in Syria (E7) is identified as the highest yielding and best correlated site and therefore it is recommended as a key location for evaluation of wheat germplasm yield potential in ICARDA's wheat breeding program. We recommend the high yielding and Ug99 resistant genotypes identified in this study for direct release as replacement of the susceptible varieties by the respective NARS and/or to be used as parents at ICARDA and by NARS collaborators. [ABSTRACT FROM AUTHOR]

The kinetics of microperoxidase-11 (MP-11) in the oxidation reaction of guaiacol (AH) by hydrogen peroxide was studied, taking into account the inactivation of enzyme during reaction by its suicide substrate, H2O2. Concentrations of substrates were so selected that: 1) the reaction was first-order in relation to benign substrate, AH and 2) high ratio of suicide substrate to the benign substrate, [H2O2]>>[AH]. Validation and reliability of the obtained kinetic equations were evaluated in various nonlinear and linear forms. Fitting of experimental data into the obtained integrated equation showed a close match between the kinetic model and the experimental results. Indeed, a similar mechanism to horseradish peroxidase was found for the suicide-peroxide inactivation of MP-11. Kinetic parameters of inactivation including the intact activity of MP-11, αi, and the apparent inactivation rate constant, ki, were obtained as 0.282 ± 0.006 min- 1 and 0.497 ± 0.013 min- 1 at [H2O2] = 1.0 mM, 27°C, phosphate buffer 5.0 mM, pH = 7.0. Results showed that inactivation of microperoxidase as a peroxidase model enzyme can occur even at low concentrations of hydrogen peroxide (0.4 mM). [ABSTRACT FROM AUTHOR]

Abstract: Kinetics of urease denaturation by anionic surfactant (sodium n-dodecyl sulphate, SDS) at concentrations below the critical micelle concentration (CMC) is investigated spectrophotometrically at neutral pH and the corresponding two-phase kinetic parameters of the process are estimated from a three-state reversible process using a binomial exponential relation based on the relaxation time method as: Using a prepared computer program, the experimental data are properly fitted into a binomial exponential relation, considering a two-phase denaturation pathway including a kinetically stable folded intermediate formed at SDS concentration of 1.1mM. Forward and backward rate constants are estimated as: k 1 =0.2141±4.5×10−3, k 2 =5.173×10−3 ±8.3×10−5, k −1 =0.09432±3.6×10−4 and k −2 =2.079×10−3 ±5.6×10−5 s−1 for the proposed mechanism. The rate-limiting step as well as the reaction coordinates in the denaturation mechanism are established. The mechanism involves formation of a kinetically stable folded native like intermediate through the electrostatic interactions. The intermediate was found to be more stable even than the native form (by about 9kJmol−1) and still hexamer, because no loss of amplitude was observed. Electrophoresis experiments on the native and surfactant/urease complexes indicated a higher mobility for the kinetically folded native like intermediate. [Copyright &y& Elsevier]

In the presence of the anionic surfactant sodium n-dodecyl sulphate (SDS), horseradish peroxidase (HRP) undergoes a deactivation process. Suicide inactivation of horseradish peroxidase by hydrogen peroxide(3&ThickSpace;mM) was monitored by the absorbance change in product formation in the catalytic reaction cycle. The progress curve of the catalytic reaction cycle was obtained at 27°C and phosphate buffer 2.5&ThickSpace;mM The corresponding kinetic parameters i.e., intact enzyme activity (αi); the apparent rate constant of suicide inactivation by peroxide (ki); and the apparent rate constants of enzyme deactivation by surfactant (kd) were evaluated from the obtained kinetic equations. The experimental data are accounted for by the equations used in this investigation. Addition of SDS to the reaction mixture intensified the inactivation process. The deactivation ability of denaturant could be resolved from the observed inactivation effect of the suicide substrate by applying the proposed model. The results indicate that the deactivation and the inactivation processes are independent of each other. [ABSTRACT FROM AUTHOR]

A new efficient extractant of polyalkyl phosphazenes, PN-1200 (supplied by All-Russian Research Institute of Chemical Technology), was used for the separation of uranium from wet process phosphoric acid (PA) in a batch process at laboratory scale. Solvent extraction of uranium from 29% P2O5 phosphoric acid using PN-1200 was compared with uranium extraction from phosphoric acid using synergistic mixtures of D2EHPA+TOPO and D2EHPA+TRPO. All extractants were diluted in normal aliphatic kerosene.It is concluded that PN-1200 has some good properties, such as high uranium distribution coefficient, good stability, acceptable kinetics, good phase separation, and simultaneous extraction of U4+ and U6+. [Copyright &y& Elsevier]

Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV–Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM). [Copyright &y& Elsevier]

Scintillation detectors are widely used in the experimental setup for the detection of charged particles. These detectors are able to measure the energy and time-of-flight of the charged particles. Also, they can be used to identify the detected particle. The probability of hadronic interaction between the detected particle and the nuclei of the scintillator atoms is one important issue that must be considered in the analysis of the detectors output. The hadronic interaction causes particles the deposit only a part of their energy inside the detector. In this case, particle will appear in the tail of energy spectrum and is mixed with the background events. Therefore, the measured cross section, which is calculated using the number of particles that deposit their full energy in the detector will be underestimated and one should correct the cross section for the lost events. The percentage of incident particles for which the hadronic interaction occurs is determined by different methods. In this paper, using two different methods, Monte-Carlo simulation and experimental data for several different channels in the proton-deuteron and deuteron-deuteron scattering at intermediate energy are introduced. The obtained results from the two methods are consistent with each other. [ABSTRACT FROM AUTHOR]

Abstract: Electrolyte Cubic Square-Well Equation of State, eCSW EoS [A. Haghtalab, S.H. Mazloumi, Fluid Phase Equilibr. 285 (2009) 96–104] is applied to compute the hydrate equilibrium conditions of the various systems. This equation based upon the Helmholtz free energy consists of the one non-electrolyte term and the two electrolyte terms. The non-electrolyte term is Cubic Square-Well Equation of State (CSW EoS) and the two electrolyte contributions consist of a Born energy and the mean spherical approximation terms. In this work, eCSW EoS is coupled with the van der Waals–Platteeuw model and applied to compute gas hydrate formation conditions. Equilibrium calculation is performed to regression of the Langmuir constants against temperature for N2, CH4, C2H6, C3H8, i-C4H10, n-C4H10 and CO2 hydrates using the experimental data in literature. Moreover, using eCSW EoS, some parameters such as k ij in the combining rule of the EoS, the interaction parameters of CO2–water and electrolyte–water systems are adjusted. The hydrate equilibrium conditions of the various systems including single gases, mixed gases and natural gases are predicted. The model results are compared with the calculated values using SRK and PR. Also, the equilibrium conditions of various hydrate formers in the presence of electrolytes such as NaCl, KCl, CaCl2 and their mixtures are predicted. Finally, the results of the model for different systems compared with those are obtained using HWHYD and Klauda models. A good agreement between the results indicates the reliability of the present model in prediction of the gas hydrate equilibrium conditions. [Copyright &y& Elsevier]