Performance of Coffea arabica F1 hybrids in agroforestry and full-sun cropping systems in comparison with American pure line cultivars

Coffea arabica F1 hybrids derived from crosses between wild Sudan-Ethiopian and American cultivars and propagated by somatic embryogenesis have been obtained in Central America. These new hybrids considerably enhanced the genetic diversity of coffee in the region. We conducted 15 trials to assess whether using hybrids represents substantial genetic progress in terms of productivity in agroforestry and full-sun cropping systems. The new germplasm was grown in the same conditions as the best American cultivar (homozygous pure lines). The results showed that yields of hybrids were earlier and superior to those of American cultivars. The hybrids were also more stable than the American cultivars in all environments. In the agroforestry system, the mean yield of hybrids was 58% higher than that of the American cultivars, while the mean yield of hybrids in the full-sun system was 34% higher. Coffee-based agroforestry systems (AS) are considered effective in protecting the environment in the volcanic cordilleras of Central America. We found that introducing hybrids in coffee-based AS can considerably increase productivity. This finding could be a convincing argument to encourage coffee growers who have adopted the full-sun cropping system to return to agroforestry cropping systems. Finally, the conditions for large-scale dissemination of those new hybrids—which represent a major innovation for C. arabica cropping—was analysed

Ferromagnetism in CdOX (X = Mn and N) with and without intrinsic point defects : A density functional theory

The purpose of this study is to further understanding of the structural, electronic, magnetic properties of CdO doped with transition metal (Mn) and non metal element (N). The calculations are performed by the developed full-potential augmented plane wave plus local orbitals method within the spin density functional theory. As exchange-correlation potential we used the generalized gradient approximation (GGA) form. Moreover, the electronic structure study for our compounds was performed with and without oxygen deficiency. We treated the ferromagnetic and antiferromagnetic states and we found that all compounds are stable in the ferromagnetic structure, and all doped materials CdO:Mn and CdO: N adopt the half metallic character. In addition, we notice that the oxygen vacancy destroyed the ferromagnetism in N doped CdO, while Mn doped CdO becomes semiconductor

Full potential linearized augmented plane wave calculations of structural and electronic properties of GeC, SnC and GeSn

cited By 28International audienceA theoretical study of structural and electronic properties of GeC, SnC and GeSn is presented using the full potential linearized augmented plane wave method. In this approach, the generalized gradient approximation was used for the exchange-correlation potential. Results are given for lattice constant, bulk modulus and its pressure derivative in both zinc-blende and rocksalt structures. Band structure, density of states and band gap pressure coefficients in zinc-blende structure are also given. The results are compared with previous calculations and with experimental measurements. © 2003 Elsevier B.V. All rights reserved

First-principle study of structural, electronic and elastic properties of SrS, SrSe and SrTe under pressure

cited By 63International audienceThe full-potential linearized augmented plane wave method (FP-LAPW) within the generalized gradient approximation (GGA) is used to calculate the electronic band structures and the total energies of SrS, SrSe and SrTe in NaCl- and CsCl-type structures. The latter provide us with the ground state properties such as lattice parameter, bulk modulus and its pressure derivative, elastic constants and the structural phase stability of these compounds. The transition pressures at which these compounds undergo structural phase transition from NaCl to CsCl phase are calculated. The energy band gaps at room conditions in NaCl structure and volume dependence of the band gaps in the CsCl structure are presented. The pressure and volume at which band overlap metallization occurs are also determined. The ground state properties, the transition and metallization pressures (volumes) are found to agree with the experimental and other theoretical results. The elastic constants at room conditions in both NaCl and CsCl structures are calculated and compared with the available theoretical results for SrSe while, for SrS and SrTe, the elastic constants are not available. © 2003 Elsevier B.V. All rights reserved

Investigating hazardous 4-aminoantipyrine with functionalized Eco-friendly Fe3O4 nanoparticles decorated nontoxic Molybdenum disulfide nanosheet sensor

In the current study, a new sensor for sensing AAP in pH 3.0 is being developed employing Hydrocerol-A coated green magnetite nanoparticle (HCA-Fe3O4) wrapped MoS2 nanocomposite modified glassy carbon electrode (HCA-Fe3O4/MoS2@GCE). The electrode material was characterized by CV, SEM, EDX, XRD, and EIS. The proposed sensor showed strong electrocatalytic activity and electrooxidation towards 4-aminoantipyrine with higher peak shift compared to the bare electrode. A plausible mechanism has been suggested to account for the participation of protons and electrons in the oxidation reaction of 4-aminoantipyrine. The quantification of the sensor was conducted using SWV studies under optimized conditions. The obtained results demonstrated that the sensor exhibited a low limit of detection of 9.8 nM and a quantification limit of 30 nM. Additionally, the sensor displayed a wide linear dynamic range spanning from 0.08 to 20 μM. The sensor that was developed demonstrated favorable selectivity for the electrochemical detection of AAP, even in the presence of interferants. Moreover, the artificially created sensor was evaluated for its feasibility in contaminated biological and water samples

First-principles calculations of optical properties of GeC, SnC and GeSn under hydrostatic pressure

cited By 25International audienceWe present first-principles of the full-potential linearized augmented plane wave calculations of the effect of hydrostatic pressure on the optical properties of zinc-blende GeC, SnC and GeSn compounds. The refractive index and its variation with hydrostatic pressure are well described. An accurate calculation of linear optical functions (refraction index and its pressure derivative, and both imaginary and real parts of the dielectric function) is performed in the photon energy range up to 15 eV. The predicted optical constants agree well with the available experimental and theoretical ones. © 2004 Elsevier B.V. All rights reserved

Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF₃

We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF₃ perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke-Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities $C_V$ and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account

Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF 3

We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF₃ perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke-Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities $C_V$ and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account

Role of exopolysaccharide in Aggregatibacter actinomycetemcomitans-induced bone resorption in a rat model for periodontal disease.

Aggregatibacter actinomycetemcomitans a causative agent of periodontal disease in humans, forms biofilm on biotic and abiotic surfaces. A. actinomycetemcomitans biofilm is heterogeneous in nature and is composed of proteins, extracellular DNA and exopolysaccharide. To explore the role played by the exopolysaccharide in the colonization and disease progression, we employed genetic reduction approach using our rat model of A. actinomycetemcomitans-induced periodontitis. To this end, a genetically modified strain of A. actinomycetemcomitans lacking the pga operon was compared with the wild-type strain in the rat infection model. The parent and mutant strains were primarily evaluated for bone resorption and disease. Our study showed that colonization, bone resorption/disease and antibody response were all elevated in the wild-type fed rats. The bone resorption/disease caused by the pga mutant strain, lacking the exopolysaccharide, was significantly less (P < 0.05) than the bone resorption/disease caused by the wild-type strain. Further analysis of the expression levels of selected virulence genes through RT-PCR showed that the decrease in colonization, bone resorption and antibody titer in the absence of the exopolysaccharide might be due to attenuated levels of colonization genes, flp-1, apiA and aae in the mutant strain. This study demonstrates that the effect exerted by the exopolysaccharide in A. actinomycetemcomitans-induced bone resorption has hitherto not been recognized and underscores the role played by the exopolysaccharide in A. actinomycetemcomitans-induced disease