Effect of bicarbonate on uptake and translocation of 59Fe in two grapevine rootstocks differing in their resistance to Fe deficiency chlorosis

In order to study the effect of high bicarbonate concentration in the root medium on root FeIII reduction, Fe uptake and its translocation to the leaves, two rootstocks (Vitis riparia Michx., susceptible, and 41 B (Vitis vinifera L. cv. Chasselas x Vitis berlandieri Planch.), resistant to Fe deficiency chlorosis) were pre-cultivated in nutrient solutions with high and low Fe supply. After three weeks of preculture at low Fe, chlorosis symptoms occurred in both, Fe-resistant and Fe-susceptible genotypes. The FeIII reducing capacity by roots was enhanced at Fe deficiency in both genotypes, which was consistent with the increase of subsequent root uptake and translocation rates of 59Fe. In the presence of bicarbonate in the solutions the FeIII reducing capacity, 59Fe uptake and translocation rate decreased in both genotypes precultured with low re supply. The 59Fe uptake and translocation rate, however, were significantly higher in the Fe chlorosis-resistant rootstock 41 B. These results clearly indicate that bicarbonate-induced Fe chlorosis in grapevine rootstocks is obviously caused by an inhibition of Fe uptake and translocation due to an inhibition of FeIII reduction by root cells. The fact that these processes were less inhibited in the chlorosis-resistant rootstock hints to genotypical differences in Fe acquisition by roots at high bicarbonate levels. These differences might be used in breeding programs to identify Fe chlorosis-resistant rootstocks

Optimization of Quercetin Extraction from Green Tea (Camellia sinensis) Using Central Composite Design, and the Pharmacological Activity of the Extract

The aim of this paper was to optimize an extraction procedure of quercetin from green tea using central composite design. Extraction time, ethanol concentration, and solid to liquid ratio were selected as the independent variables, while quercetin yield was defined as a response. The impact of factors and their interactions on the quercetin yield was studied based on the results of ANOVA test. The extraction time of 58.5 min, ethanol concentration of 94.7 % (v/v), and solid to liquid ratio of 1:19.4 (m/v) were found as the optimal conditions. The experimental confirmation of the proposed optimal conditions indicated that there was a good agreement between the experimental and predicted values. In addition to quercetin, the presence of 17 bioactive compounds was confirmed in the green tea extract using mass spectrometry method. Antioxidant, antimicrobial and antitumor activity of the optimal extract was determined using DPPH assay, disk diffusion method, and MTT assay, respectively

The Effects of Aggressive Environments on the Properties of Fly Ash based Geopolymers

This paper analyzes the effects of two different aggressive environments, concentrated ammonium nitrate solution (480 g/dm(3)) and sodium sulphate solution (50 g/dm(3)), on the structure and mechanical strength of fly ash based geopolymers. Geopolymer samples were subjected to the aggressive solutions over a period of 365 days. It was found that exposure to the NH4NO3 and Na2SO4 solutions caused small decrease in geopolymer strength (10-20 %). The most valuable insight into the structural changes caused by testing of the geopolymer samples in the aggressive solutions was provided by means of Si-29 MAS NMR. It was found that the immersion of geopolymer samples in the NH4NO3 solution caused breaking of Si-O-Al bonds in the aluminosilicate geopolymer gel structure. On the other hand, treatment of the geopolymer samples with the Na2SO4 solution resulted in breaking of Si-O-Si bonds in geopolymer gel structure and leaching of Si. It was concluded that the major changes in the geopolymer structure were associated with the changes in the pH values of aggressive solutions during the testing

A simulation study of the combined thermoelectric extracellular stimulation of the sciatic nerve of the Xenopus laevis: the localized transient heat block

The electrical behavior of the Xenopus laevis nerve fibers was studied when combined electrical (cuff electrodes) and optical (infrared laser, low power sub-5 mW) stimulations are applied. Assuming that the main effect of the laser irradiation on the nerve tissue is the localized temperature increase, this paper analyzes and gives new insights into the function of the combined thermoelectric stimulation on both excitation and blocking of the nerve action potentials (AP). The calculations involve a finite-element model (COMSOL) to represent the electrical properties of the nerve and cuff. Electric-field distribution along the nerve was computed for the given stimulation current profile and imported into a NEURON model, which was built to simulate the electrical behavior of myelinated nerve fiber under extracellular stimulation. The main result of this study of combined thermoelectric stimulation showed that local temperature increase, for the given electric field, can create a transient block of both the generation and propagation of the APs. Some preliminary experimental data in support of this conclusion are also shown

Far infrared and photoacoustic characterization of iodine doped PbTe

Single crystal samples of PbTe doped with PbI2 were made using the Bridgman technique. Far infrared reflectivity diagrams of PbTe doped with 0.4 at% and 0.6 at% Iodine were measured and numerically analyzed. A plasma resonance at about 650 cm(-1) with the reflectivity minima very close to zero was observed for both samples. Thermal diffusivity was determined for the same samples using the photoacoustic method with a transmission detection configuration and the values of the minority free carrier (holes) mobility were calculated

Star Formation Near Photodissociation Regions: Detection of a Peculiar Protostar Near Ced 201

We present the detection and characterization of a peculiar low-mass protostar (IRAS 22129+7000) located ~0.4 pc from Ced 201 Photodissociation Region (PDR) and ~0.2 pc from the HH450 jet. The cold circumstellar envelope surrounding the object has been mapped through its 1.2 mm dust continuum emission with IRAM-30m/MAMBO. The deeply embedded protostar is clearly detected with Spitzer/MIPS (70 um), IRS (20-35 um) and IRAC (4.5, 5.8, and 8 um) but also in the K_s band (2.15 um). Given the large "near- and mid-IR excess" in its spectral energy distribution, but large submillimeter-to-bolometric luminosity ratio (~2%), IRAS 22129+7000 must be a transition Class 0/I source and/or a multiple stellar system. Targeted observations of several molecular lines from CO, 13CO, C18O, HCO+ and DCO+ have been obtained. The presence of a collimated molecular outflow mapped with the CSO telescope in the CO J=3-2 line suggests that the protostar/disk system is still accreting material from its natal envelope. Indeed, optically thick line profiles from high density tracers such as HCO+ J=1-0 show a red-shifted-absorption asymmetry reminiscent of inward motions. We construct a preliminary physical model of the circumstellar envelope (including radial density and temperature gradients, velocity field and turbulence) that reproduces the observed line profiles and estimates the ionization fraction. The presence of both mechanical and (non-ionizing) FUV-radiative input makes the region an interesting case to study triggered star formation