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[en] The effect of water stress on the regulation of ethylene biosynthesis has not yet clearly been established. Both the formation and utilization of aminocyclopropane-1-carboxylic acid, ACC, are considered to be major regulatory points in ethylene biosynthesis. There is evidence that ACC synthase is the key control enzyme in response to various stimuli associated with the induction of ethylene biosynthesis. It has been reported that aminoisobutyric acid, AIB, inhibits ethylene production in some plants and AIB may inhibit the conversion of ACC to ethylene. For this reason, the possibility of inhibition of ACC uptake in the presence of AIB was examined. It was observed that the rate of ¹⁴C-ACC uptake decreased with an increase in the concentration of AIB in the solution. Calculating the percentage of ACC converted to ethylene on the basis of uptake shows that AIB inhibits the conversion of ¹⁴C-ACC to ethylene and that this inhibition is increased with an increase in the concentration of AIB in the solution. This suggests that a portion of the inhibition of the conversion of ACC to ethylene in the presence of AIB is partly due to the competition for absorption. However, the ability of AIB to inhibit ethylene production in leaf tissue without an exogenous supply of ACC clearly indicates that AIB inhibits ethylene production. The present study was undertaken to elucidate the regulation of ethylene biosynthesis in water-stressed plants and the results are discussed

[en] The effects of dietary nickel oxide nanoparticles (NiO-NPs) contamination along with silymarin supplementation on pancreatic tissue of rainbow trout fingerlings were investigated. Five treatments including different levels of NiO-NPs (0, 100 and 500 mg kg⁻¹ feed) and silymarin (0 and 1 g kg⁻¹ feed) in three respective replicates were designed. The trial was conducted under 12L:12D photoperiod condition for 60 days. Tissue samples for histological and enzymatic studies were taken on days 30 and 60. The results from day 30 indicated that the highest and lowest alkaline protease activities were belonged to fish fed diet without any nanoparticles (T1) and those fed 100 or 500 mg kg⁻¹ feed (T4 and T5), respectively. Dietary silymarin could to some extent prevent toxic effects of NiO-NPs on enzyme activity (T2 vs. T3). Acinar cells necrosis, edema of connective tissue and cellular shrinkage were observed in NiO-NPs received groups (T4 and T5). At the end of the trial, T2 and T3 could regain their digestive capacity after removal of nanoparticles and those groups continued to receive nanoparticles until the end of the trial (T4 and T5) showed the lowest alkaline protease activity. Moreover, the histological observations revealed pancreas tissue necrosis, nuclear degeneration and vascular dilation in the latter groups. In conclusion, NiO-NPs affected pancreatic tissue and its function in a dose-dependent manner, while dietary silymarin helped fish to sustain digestive capacity. Future researches should focus on the ecological outcomes of pollutants induced toxicity.

[en] Spinel Ni_0.3Zn_0.7Fe₂O₄ (NZFO) magnetic nanoparticles was prepared by the low temperature auto-combustion method using a glycine fuel-rich composition without any further heat treatment at high temperature. Subsequently, the synthesized MNPs were coated with Pluronic P123 (PP123) after its surface was functionalized with oleic acid (OA). The effect of the coatings on the morphology, structural and magnetic properties of NZFO nanoparticles was studied using powder X-ray diffraction (XRD), Fourier transform infrared, thermogravimetric analysis, field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The colloidal behaviour of coated MNPs in physiological saline medium like water or phosphate buffer saline (PBS) was also studied by zeta potential measurements. XRD results showed the formation of cubic spinel crystalline phase with and without OA–PP123 coatings. Also, after OA–PP123 coating, the crystallite size (from Scherrer formula) decreases from 55 to 53 nm. However, an enlargement in the particle size and a reduction in agglomeration were observed from FE-SEM results when the nanoparticles were coated with OA–PP123. VSM measurements showed ferromagnetic behaviour at room temperature before and after coating. The colloidal stability study of the coated sample revealed a considerable high zeta potential value at physiological pH (7.4) highlighting its potential biomedical applications.

[en] The energy for heavy ion interaction of ¹⁶O + ²⁰⁹Bi and ³²S + ¹⁸¹Ta is considered here. These reactions have considerable fusion cross-section and the compound nucleus formed makes fission immediately. For the proposed thick target and calculated number of emitted neutrons, the energy gains of 15.6 and 9 are obtained respectively. To evaluate our used theories here, ¹⁶O + ¹⁹⁷Au reaction is used. Existing reliable experimental information on this reaction greatly helped in application of the used theory for it and the obtained gain is 17.5. In continuation of our gain studies we calculated the gain for neutron rich projectile of ³⁸S on ¹⁸¹Ta. The obtained energy gain is 13 which is 1.5 times the gain ³²S + ¹⁸¹Ta reaction. This increase is due to a reduction on the fusion potential barrier which results in fusion cross-section enhancement. Finally, comparison of obtained results with the gain of other designs of light ion fusion systems suggests that the proposed reactions are favorable

[en] Compound-nucleus reactions provide the standard mechanism to populate states with high angular momentum in neutron deficient nuclei. Neutron-rich nuclei with mass A<150 can be studied in spontaneous and induced fission. Projectile fragmentation has proven to be an efficient method of populating nuclei far from the valley of stability. However, in the case of heavy nuclei this method is still limited to species with isomeric states. Deep-inelastic reactions are another reaction mechanism which can be used to study neutron rich nuclei and are able to populate relatively high-spin states. In this article we compare the advantages and disadvantages of each method.

[en] In this experimental work the pressure induced phase transformation of silicon and Germanium has been studied. It was shown that at a particular value of applied pressure, (P_t), depending on the sample temperature, the electrical resistance of the specimen falls off to a metallic state. The main goal of this study was to find out how the phase transformation pressure, P_t, for a p-type silicon varies with the sample temperature. The results show that, the value of P_t, decreases linearly as the temperature of the sample increases. Meanwhile, other related results including the rate of resistance change in accordance with applied pressure on the sample at different temperatures (∼270-350 K), both for the semiconductor and the metallic state of the specimen were determined. In another effort, the amount of P_t, for an n-type germanium, but only at room temperature, was also determined

[en] In this paper, we present a local approach to the entropy of doubly stochastic operators. The definition of the local entropy follows some steps, motivated by Downarowicz and Frej (Ergod Theory Dyn Syst 25(2):455–481, 2005). It results in a local approach to the entropy of doubly stochastic operators with finite numbers of ergodic measures as well as Koopman operators.

[en] We carried out the theoretical study of the influence of temperature on the polaron vibration frequency in the RbCl asymmetrical semi-exponential quantum wells by using the quantum statistical theory. The vibration frequency and the ground-state binding energy (GSBE) varying with the temperature and the Coulomb interaction are calculated by employing the Lee–Low–Pines transformation method combined with linear combination operation technique. We show that the vibration frequency and the GSBE will be enhanced with raising the temperature and the Coulomb repulsion interaction.

[en] Lead sulfide thin films were prepared at 25 °C temperature using chemical bath deposition (CBD) on both Si (100) and glass substrates. XRD analysis of the PbS film shows that the prepared films have a polycrystalline structure with (200) preferential orientation. The grains become smaller with increasing the deposition concentration. X-ray photoelectron spectroscopy (XPS) demonstrated the presence of lead sulfide as PbS. The composition of the prepared films is investigated by energy-dispersive X-ray spectroscopy technique, and it was found that the films are stoichiometric and have low oxygen contamination. Raman and XPS spectra confirm that the CBD method is a decent one to acquire stoichiometric PbS film with nanostructures. Atomic force microscopy was applied to investigate the change in the films morphology with the concentration. The effect of the concentration, on both optical transmittance in the UV–NIR region and the structure of the film, was studied. The results revealed that the optical band gap increased slightly when the concentration increased together with the grain size evolution.