Development of an apparatus for obtaining molecular beams in the energy range from 2 to 200 eV

The formation and detection of molecular beams obtained by charge exchange from a low-energy ion source is discussed. Dispersion in energy of the ion source was measured and problems concerning detection of neutral beams were studied. Various methods were used, specifically secondary electron emissivity of a metallic surface and ionization of a gas target with a low ionization voltage. The intensities of neutral beams as low as 10 eV are measured by a tubular electron multiplier and a lock-in amplifier

Synthesis, characterization and antibacterial activity studies of new 2‑pyrral‑L‑amino acid Schif base palladium (II) complexes.

Three new 2-pyrral amino acid Schif base palladium (II) complexes were synthesized, characterized and their activity against six bacterial species was investigated. The ligands: Potassium 2-pyrrolidine-L-methioninate (L1), Potassium 2-pyrrolidine-L-histidinate (L2) and Potassium 2-pyrrolidine-L-tryptophanate (L3) were synthesized and reacted with dichloro(1,5- cyclooctadiene)palladium(II) to form new palladium (II) complexes C1, C2 and C3, respectively. 1 NMR, FTIR, UV–Vis,elemental analysis and conductivity measurements were used to characterize the products. The antibacterial activities of the compounds were evaluated against Gram-positive Staphylococcus aureus (S. aureus, ATCC 25923), methicillin-resistant Staphylococcus aureus (MRSA, ATCC 33591), Staphylococcus epidermidis (S. epidermidis, ATCC 12228) and Streptococcus pyogenes (S. pyogenes, ATCC 19615) and, gram-negative Pseudomonas aeruginosa (P. aeruginosa, ATCC 27853) and Klebsiella pneumoniae (K. pneumoniae, ATCC 13883) using the agar well difusion assay and microtitre plate serial dilution method. The palladium complexes were active against the selected bacteria with the imidazole ring containing complex C2 and indole heterocyclic ring containing complex C3 showing the highest activity

Integrated Control of Nitrate Uptake by Crop Growth Rate and Soil Nitrate Availability under Field Conditions

There is still disagreement about whether crop growth rate or soil nitrate concentration control nitrogen absorption by crops under ®eld conditions. The in¯uence of these factors on the control of N uptake rate was examined in the absence of water stress, using data on dry matter production, above-ground nitrogen accumulation and soil nitrate concentration from several N-fertilizer experiments on winter wheat, winter oilseed rape and maize. The results con®rmed that crops can accumulate nitrogen far in excess of the `critical dilution curve', which de®nes the minimum amount of nitrogen needed for maximal growth rate: the N concentration in plants could exceed the critical N concentration by 70 to 80 % for the three species studied. The nitrate uptake rate index (NUI) was calculated as the ratio of actual and critical N uptake rates, at intervals of 1 week. NUI varied with nitrate concentration in the 0±30 cm soil layer according to a Michaelis±Menten equation (with one or two components). This response was compared with the kinetics of saturation of the nitrate uptake systems: the high a�nity transport system (HATS) and the low a�nity transport system (LATS). As a result, it is proposed that there is a critical N dilution curve delimiting two domains of N use by plants. This is linked to the two nitrate transport systems, with HATS working at low nitrate concentrations, below the critical dilution curve, and LATS at high nitrate concentrations, above the curve. NUI provides another method for calculating the actual nitrate uptake rate, which depends on the maximal crop growt

Propositional Tree Automata

In the paper, we introduce a new tree automata framework, called propositional tree automata, capturing the class of tree languages that are closed under an equational theory and Boolean operations. This framework originates in work on developing a sufficient completeness checker for specifications with rewriting modulo an equational theory. Propositional tree automata recognize regular equational tree languages. However, unlike regular equational tree automata, the class of propositional tree automata is closed under Boolean operations. This extra expressiveness does not affect the decidability of the membership problem. This paper also analyzes in detail the emptiness problem for propositional tree automata with associative theories. Though undecidable in general, we present a semi-algorithm for checking emptiness based on machine learning that we have found useful in practice