Monitoring Soil Characteristics in Organic Farming: A Comparison of Field vs. Laboratory Methods

Soil quality plays a key role in organic farming. In practice its evaluation is not so simple because there are many indicators that could be used. In our research we used simple field methods (soil quality test kit) and compared the data with traditional evaluation used in the laboratory

Drop of Activity of the Oxygen Electrode on the Base of Ag Catalyst (Polytetrafluorethylene)

The article describes the determination of the effect of »impurities«, o,riginating from dissolution of the cell components, upon the activity of the oxygen electrode Ag-catalyst .in 7 N KOH. It was confirmed that the silver surface plays a more serious part in electrochemical processes than it had been assumed previously. It refers, above all, to the formation and solubility of silver oxides and further to eventual adsorption of ions [Ag(OH) 2]- on the active surface of the oxygen electrode silver catalyst, especially with positive potentials in unloaded conditions. For the determination of the total effect of events upon the activity of the oxygen electrode, methods comparing the changes of current density, in dependence on time, were applied. Current density was measured with electrode potential of -300 mV vs. Hg/HgO. The experiments proved that the activity of the oxygen electrode on the base of Ag catalyst ~ PTFE in unloaded conditions and without oxygen pressure in 7 N KOH at the approximate temperature of 63° C, drops expressively with time. More we observed the influence of the collector material construction, effect of Zn, Ni, Cd and Fe, effect of amalgamation of the oxygen electrode and effect of CO i- upon its activity. It was proved, on the basis of experimental results, that the oxygen electrode on the basis of Ag/PTFE is practically inapplicable. »Selfpoisoning « occurs here probably due to the effect of ions [Ag(OH) 2]-. On the other hand, the formation of [Ag(OH)2]- can be utilized in the production technology of electron conductive skeleton of the electrode by the application of a mixture of silver and electronegative metal, e. g. Zn

Phosphoglycerate kinase acts as a futile cycle at high temperature

In (hyper)thermophilic organisms metabolic processes have to be adapted to function optimally at high temperature. We compared the gluconeogenic conversion of 3-phosphoglycerate via 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate at 30 C and at 70 C. At 30 C it was possible to produce 1,3-bisphosphoglycerate from 3-phosphoglycerate with phosphoglycerate kinase, but at 70 C, 1,3-bisphosphoglycerate was dephosphorylated rapidly to 3-phosphoglycerate, effectively turning the phosphoglycerate kinase into a futile cycle. When phosphoglycerate kinase was incubated together with glyceraldehyde 3-phosphate dehydrogenase it was possible to convert 3-phosphoglycerate to glyceraldehyde 3- phosphate, both at 30 C and at 70 C, however, at 70 C only low concentrations of product were observed due to thermal instability of glyceraldehyde 3-phosphate. Thus, thermolabile intermediates challenge central metabolic reactions and require special adaptation strategies for life at high temperature

Nonlinear resonant behavior of the dispersive readout scheme for a superconducting flux qubit

A nonlinear resonant circuit comprising a SQUID magnetometer and a parallel capacitor is studied as a readout scheme for a persistent-current (PC) qubit. The flux state of the qubit is detected as a change in the Josephson inductance of the SQUID magnetometer, which in turn mediates a shift in the resonance frequency of the readout circuit. The nonlinearity and resulting hysteresis in the resonant behavior are characterized as a function of the power of both the input drive and the associated resonance peak response. Numerical simulations based on a phenomenological circuit model are presented which display the features of the observed nonlinearity.Comment: 9 pages, 9 figure

Unique organization of photosystem II supercomplexes and megacomplexes in Norway spruce

Photosystem II (PSII) complexes are organized into large supercomplexes with variable amounts of light-harvesting proteins (Lhcb). A typical PSII supercomplex in plants is formed by four trimers of Lhcb proteins (LHCII trimers), which are bound to the PSII core dimer via monomeric antenna proteins. However, the architecture of PSII supercomplexes in Norway spruce[Picea abies (L.) Karst.] is different, most likely due to a lack of two Lhcb proteins, Lhcb6 and Lhcb3. Interestingly, the spruce PSII supercomplex shares similar structural features with its counterpart in the green alga Chlamydomonas reinhardtii [Kouřil et al. (2016) New Phytol. 210, 808–814]. Here we present a single-particle electron microscopy study of isolated PSII supercomplexes from Norway spruce that revealed binding of a variable amount of LHCII trimers to the PSII core dimer at positions that have never been observed in any other plant species so far. The largest spruce PSII supercomplex, which was found to bind eight LHCII trimers, is even larger than the current largest known PSII supercomplex from C. reinhardtii. We have also shown that the spruce PSII supercomplexes can form various types of PSII megacomplexes, which were also identified in intact grana membranes. Some of these large PSII supercomplexes and megacomplexes were identified also in Pinus sylvestris, another representative of the Pinaceae family. The structural variability and complexity of LHCII organization in Pinaceae seems to be related to the absence of Lhcb6 and Lhcb3 in this family, and may be beneficial for the optimization of light-harvesting under varying environmental conditions