224 research outputs found

    Effect of Grafting on Tomato Fruit Quality

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    The study aimed to assess if grafting affects tomato fruit quality. The research has been conducted in greenhouses where grafted and ungrafted tomatoes have been produced. A Romanian tomato hybrid and a Dutch tomato hybrid, ‘Siriana’ F1 and ‘Abellus’ F1, were used as scions and four cultivars of the Lycopersicon genus, ‘Emperador’ F1 (Dutch hybrid), ‘L542’, ‘L543’ and ‘L544’ (Romanian cultivars) were used as rootstocks. Eight grafted variants (‘Siriana’בEmperador’, ‘Siriana’בL542’, ‘Siriana’בL543’, ‘Siriana’בL544’, ‘Abellus’× ‘Emperador’, ‘Abellus’בL542’, ‘Abellus’בL543’, ‘Abellus’בL544’) and two ungrafted variants (‘Siriana’, control and ‘Abellus’, control) were obtained. The tomato fruit quality has been observed at ‘Siriana’ and ‘Abellus’ grafted on all rootstocks. Compared to ungrafted tomatoes, which have yielded 80.1% and 85.3% of extra and first quality fruits, ‘Siriana’ and ‘Abellus’ grafted on ‘Emperador’ have had a very good fruit quality, 82.3% and 86.8% and grafted on Romanian cultivars have had a quality between 79.1-79.8% and 84.1-84.4% to the same quality standards. Analyzing the dependence between the quality categories (extra and first class) and the soluble dry substance content, a positive dependence was observed between grafted plants and ungrafted plants at both hybrids, ‘Siriana’ r2 = 0.4914 and ‘Abellus’ r2 = 0.1517 and the carbohydrates content, a negative dependence was observed between grafted plants and ungrafted plants at both hybrids, ‘Siriana’ r2 = 0.017 and ‘Abellus’ r2 = 0.798. The total vitamin C content has decreased after grafting. The grafting has had an influence on the soluble dry substance content, the total amount of carbohydrates and vitamin C at all grafting combinations. It can be said that the rootstocks played an important role on the fruit quality

    Field-induced phase transitions in a Kondo insulator

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    We study the magnetic-field effect on a Kondo insulator by exploiting the periodic Anderson model with the Zeeman term. The analysis using dynamical mean field theory combined with quantum Monte Carlo simulations determines the detailed phase diagram at finite temperatures. At low temperatures, the magnetic field drives the Kondo insulator to a transverse antiferromagnetic phase, which further enters a polarized metallic phase at higher fields. The antiferromagnetic transition temperature TcT_c takes a maximum when the Zeeman energy is nearly equal to the quasi-particle gap. In the paramagnetic phase above TcT_c, we find that the electron mass gets largest around the field where the quasi-particle gap is closed. It is also shown that the induced moment of conduction electrons changes its direction from antiparallel to parallel to the field.Comment: 7 pages, 6 figure

    Thermodynamics of clay – Drug complex dispersions: Isothermal titration calorimetry and high-performance liquid chromatography

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    An understanding of the thermodynamics of the complexation process utilized in sustaining drug release in clay matrices is of great importance. Several characterisation techniques as well as isothermal calorimetry were utilized in investigating the adsorption process of a model cationic drug (diltiazem hydrochloride, DIL) onto a pharmaceutical clay system (magnesium aluminium silicate, MAS). X-ray powder diffraction (XRPD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and optical microscopy confirmed the successful formation of the DIL-MAS complexes. Drug quantification from the complexes demonstrated variable behaviour in the differing media used with DIL degrading to desacetyl diltiazem hydrochloride (DC-DIL) in the 2 M HCl media. Here also, the authors report for the first time two binding processes that occurred for DIL and MAS. A competitor binding model was thus proposed and the thermodynamics obtained suggested their binding processes to be enthalpy driven and entropically unfavourable. This information is of great importance for a formulator as care and consideration should be given with appropriate media selection as well as the nature of binding in complexes

    Principles of Quantitative Fluid and Cation Replacement in Extreme Hyperglycemia

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    Hyperglycemia may cause profound deficits of water, sodium and potassium through osmotic diuresis, which continues during treatment as long as there is glucosuria. Replacement fluids should cover both the deficits at presentation and the ongoing losses during treatment. At presentation with hyperglycemia, quantitative estimates of the deficits in water, sodium and potassium are based on rapid body weight changes, which indicate changes in body water, and on the serum sodium concentration corrected to a normal serum glucose level. The corrected serum sodium concentration provides a measure of the water deficit relative to the cation deficit (sodium, plus potassium) that is useful in guiding the choice of monovalent cation concentration in the initial replacement fluids. Monitoring clinical status, serum chemistries (glucose, sodium, potassium, total carbon dioxide), urine flow rate, and urine chemistries (sodium and potassium) during the course of fluid and cation replacement therapy is critical. This monitoring guides the volume and composition of replacement solutions for deficits developing during treatment and the management of potassium balance and acid-base abnormalities, including metabolic acidosis, respiratory acidosis, rarely, and others

    First order transition from correlated electron semiconductor to ferromagnetic metal in single crystalline FeSi1-xGex

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    The phase diagram of FeSi1-xGex, obtained from magnetic, thermal and transport measurements on single crystals, shows a first-order transition from a correlated electron semiconductor to a ferromagnetic metal at a critical concentration, x ~ 0.25. The gap of the insulating phase strongly decreases with x. The specific heat coefficient appears to track the density of states of a Kondo insulator. The phase diagram is consistent with a correlation induced insulator-metal transition in conjunction with disorder on the Si/Ge ligand site

    Effective three-band model for double perovskites

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    We start from a six-band model describing the transition-metal t2g orbitals of half-metallic double perovskite systems, such as Sr2FeMoO6, in which only one of the transition metal ions (Fe) contains important intratomic repulsion Ufe. By eliminating the Mo orbitals using a low-energy reduction similar to that used in the cuprates, we construct a Hamiltonian which contains only effective t2g Fe orbitals. This allows to treat exactly Ufe, and most of the Fe-Mo hopping. As an application, we treat the effective Hamiltonian in the slave-boson mean-field approximation and calculate the position of the metal-insulator transition and other quantities as a function of pressure or on-site energy difference.Comment: 8 pages, 3 figure

    Critical fluctuation conductivity in layered superconductors in strong electric field

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    The paraconductivity, originating from critical superconducting order-parameter fluctuations in the vicinity of the critical temperature in a layered superconductor is calculated in the frame of the self-consistent Hartree approximation, for an arbitrarily strong electric field and zero magnetic field. The paraconductivity diverges less steep towards the critical temperature in the Hartree approximation than in the Gaussian one and it shows a distinctly enhanced variation with the electric field. Our results indicate that high electric fields can be effectively used to suppress order-parameter fluctuations in high-temperature superconductors.Comment: 11 pages, 2 figures, to be published in Phys. Rev.

    Dimensional Crossover of Weak Localization in a Magnetic Field

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    We study the dimensional crossover of weak localization in strongly anisotropic systems. This crossover from three-dimensional behavior to an effective lower dimensional system is triggered by increasing temperature if the phase coherence length gets shorter than the lattice spacing aa. A similar effect occurs in a magnetic field if the magnetic length LmL_m becomes shorter than a(D∣∣/D⊥)γa(D_{||}/D_\perp)^\gamma, where \D_{||}/D_\perp is the ratio of the diffusion coefficients parallel and perpendicular to the planes or chains. γ\gamma depends on the direction of the magnetic field, e.g. γ=1/4\gamma=1/4 or 1/2 for a magnetic field parallel or perpendicular to the planes in a quasi two-dimensional system. We show that even in the limit of large magnetic field, weak localization is not fully suppressed in a lattice system. Experimental implications are discussed in detail.Comment: RevTeX, 11 pages, 4 figures; three references added and discusse

    Real time calorimetric characterisation of clay – drug complex dispersions and particles

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    Isothermal titration calorimetry (ITC) along with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and high-performance liquid chromatography (HPLC) were employed to investigate the process of adsorption of propranolol hydrochloride (PPN) onto magnesium aluminium silicate (MAS) and to characterise the MAS-PPN particles formed upon complexation. The composition of MAS was confirmed by infrared (IR) spectroscopy and a calcimeter. The calorimetric results confirmed the binding between PPN and MAS at various pHs and temperatures. The overall change in enthalpy was found to be exothermic with a comparatively small entropic contribution to the total change in Gibbs free energy. These findings suggest that the binding process was enthalpically driven and entropically unfavourable (lower affinity) suggesting hydrogen bonding and electrostatic interactions dominating the interaction. The variation of pH and temperature did not have a great impact on the thermodynamics of the binding process, as observed from the similarity in enthalpy (ΔH), entropy (ΔS) or Gibbs free energy (ΔG). A slight reduction in the binding affinity (Ka) with varing pH and temperature was however observed. SEM/EDX studies showed the occurrence of changes in the microstructural properties of MAS following complexation which may explain the potential of MAS-PPN complexes for controlled drug release promoting pharmaceutical innovation

    SALIVARY PARAMETERS ALTERED IN SMOKERS AND POSSIBLE CORRELATIONS WITH THE CARIOGENIC ACTIVITY

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    Objectives. Our research team aimed to evaluate the effects smoking has on several salivary parameters and to assess if there are any correlations between smoking and the cariogenic activity. Material and method. The present research included a total of 35 participants. Saliva was collected from every participant to the study. Salivary chloride, calcium and potassium levels, as well as salivary flux and pH were determined for all subjects. Results. Our results showed significantly lower salivary flux and pH levels in smokers compared to nonsmokers (p < 0.01). Chloride, calcium and potassium we found to have higher concentrations in smokers compared to the control group. However, a statistical significance could be found only for calcium (p = 0.02). Moreover, we were able to find in the smokers group a positive correlation in smokers between salivary chloride levels and cariogenic activity as well as a negative correlation could be found in smokers between salivary calcium levels and the cariogenic activity Conclusions. The results of the present study show that smoking alters salivary parameters and that these modifications can favour the development of dental caries
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