The ectomycorrhizal fungi Suillus granulatus and Paxillus involutus were grown in both liquid culture (LC) and in symbiosis with Pinus sylvestris seedlings under sterile conditions. In LC, the activities of tyrosinase, laccase and peroxidase, and also the oxidation rates of litter- and lignin-derived phenolics were determined. LC mycelia of S. granulatus showed intracellular tyrosinase, laccase, and peroxidase activities. In the culture fluid, extracellular laccase and tyrosinase activities were found. P. involutus predominantly produced intracellular laccase. LC mycelia of S. granulatus suspended in buffer oxidized a range of phenolic acids and mono- and diphenolic compounds by intracellular mechanisms more effectively than did mycelia of P. involutus. In addition, LC mycelia of S. granulatus oxidized p-cresol also by extracellular mechanisms. In symbiosis with Scots pine, S. granulatus and P. involutus increased the level of peroxidase in the fungus/root homogenate and in the nutrient solution of the mycorrhizal plants. Polyphenol oxidase activities were only found with S. granulatus as the mycorrhizal symbiont, and were possibly responsible for the high rate of p-cresol oxidation by this mycorrhizal association. The results suggest that fungal phenol oxidizing enzymes of ectomycorrhizas can substantially contribute to humification and detoxification processes in soil.

The effects of the phytotoxin coronatine formed bp pathovars of Pseudomonas syringae on coronatine sensitive cell cultures of Lycopersicon peruvianum and Lycopersicon esculentum were investigated. The studied parameters were ethylene release, activity of membrane-bound ATPase and vitality using the TTC test. The cells of L. esculentum responded with an increase, the cells of L. peruvianum with a decrease of ethylene formation after application of different coronatine concentrations. These results indicate that the effect on ethylene release is not the primary effect of the toxin. The activity of membrane-bound ATPase was not affected by coronatine.

The effect of the phytotoxin coronatine, formed by pathovars of Pseudomonas syringae , on the plant cell cultures of Lycopersicon peruvianum, Lycopersicon esculentum, Chenopodium album and Solanum tuberosum was investigated. The parameters studied were growth, triphenyltetrazolium chloride activity (test for reductases), cell protein content and activities of polyphenol oxidase and peroxidase, both within the cells and in the culture liquid. The cultures of Lycopersicon peruvianum and Lycopersicon esculentum cultures were more sensitive than Chenopodium album and Solanum tuberosum . The more resistant cultures possess a high level of extracellular polyphenol oxidase.

The effect of a co-cultivation with the pathogen Pseudomonas syringae pv. tomato, strain 34, on plant cell cultures of Lycopersicon esculentum and its wild type Lycopersicon peruvianum was investigated. The studied parameter were growth, vitality (TTC-test, FDA-test) cellular protein content, activities of polyphenol oxidase, peroxidase and PAL within the cells. Furthermore we estimated the rate of attached bacteria on the plant cell walls. The used tomato suspension cultures react in a quite different way to the pathogen.

Afin de pouvoir realiser une inscription ou une decoration au laser sur des substrats transparents au moyen d'un laser au neodyme, on recouvre le substrat, selon l'invention, d'une couche auxiliaire contenant deux sortes d'ions de metaux de transition qui different par leur valence ou par leur nombre atomique. Le rayonnement laser est absorbe dans la couche auxiliaire et agit de ce fait indirectement sur le substrat. Cela permet d'obtenir une ecriture reguliere, y compris a des vitesses d'inscription tres elevees.

The influence of the bacterial phytotoxin coronatine on cell cultures of Lycopersicon peruvianum and Chenopodium album was studied. It was detectable that the cell culture L. peruvianum more related to the host plant of the phytopathogenic bacteria reacts more sensitive to coronatine. Concentrations of 3.5 ng coronatine/ml culture liquid induce reductions in growth and the TTC-activity. In the case of the other used cell culture the critical amount of coronatine was higher than 7 ng/ml culture liquid. In further experiments the concentrations of free amino acids and proteins within the cell were followed. After 6-7 days of culture a slightly recovery of the cultures treated with coronatine was detectable.

Growth of the perfect YAP crystals up to 35 mm in diameter and 185 mm in length is described. The decomposition of the crystal and the iron content were suppressed by using of Ar-He-H2 protective atmosphere and negatively charged electrode above the melt level. The shape of solid-liquid interface is connected with optical homogeneity of the crystals. It may be controlled by the Ar: He ratio. The comparison with the crystals grown in vacuum is given.

AbstractSpectral properties of YAG and YAP grown in vacuum or under ArH2 protective atmosphere were compared. The latter contained small amounts of argon which was detected by a laser mass spectral analysis. Ar impurity evokes brown colour of unannealed crystals and strenghtens anomalous red colour of annealed (Particularly in O2) YAP crystals doped with Nd + Cr or Nd + Mo. The same red coloration of the doped YAGs is less stable.

YAP:Nd, Cr grown under Ar-H2 or Ar-He-H2 atmosphere possesses good energy transfer from Cr3+ to Nd3+ but suffers from the colour centre formation. The centre formation was completely prevented using further admixture of Ce3+ and 10−4−10−3 wt. % Fe. Small luminescence quenching of Cr3+ or Nd3+ due to iron ions is negligible in the presence of Ce3+. The crystals may be also heavily doped with Nd3+ because the increased pumping efficiency compensates the shortening of the luminescence lifetime. YAP: Nd, Ce, Cr, Fe is advisible active laser material particularly for all the types of pulsed lasers.

Energy transfer from Ce to Cr in YAG is radiative and relatively inefficient. If excited below ∼500 nm, the opposite transfer is dominant. YAP: Ce, Cr showed relatively efficient Ce→Cr transfer only. The sensitization of Nd3+ luminescence by Ce3+ ions depends on the overlap of the Ce3+ emission band with Nd3+ absorption lines. Cr3+→Nd3+ transfer is characterized by an expressive non-radiative portion. It is inefficient in YAG but very efficient in YAP. No UV-induced colour centres were found in YAG: Nd, Cr grown under Ar-H2 atmosphere and doped with 10−3 wt. % Cr, but at a higher Cr concentration anomalous absorption between UV absorption edge and ∼ 650 nm was stabilized. Ce3+ admixture in YAG:Nd, Cr and/or reducing treatment of the crystals facilitate the decomposition of the centres. The decomposition is accompanied with a strong Nd3+ luminescence. Therefore, YAG: Nd, Ce, Cr is an advisable active laser material. On the other hand the same centre in YAP: Nd, Cr seemed to be more stable even in the presence of cerium ions.

The growth of perfect YAP crystals doped with Nd, Cr and Ce in resistant furnace, reductive conditions and high vacuum and Mo crucible are described. The growth conditions for decreasing: decomposition of crystals, iron content and twinning are found. Distribution coefficients of dopants, some spectral and generation properties of the crystals were measured.

AbstractSpectroscopic and laser properties of YAG:Nd and YAP:Nd grown from the nonstoichiometric melts or those containing Mo and Fe impurity were compared. YAG:Nd grown from the melt with surplus of Y2O3 and annealed in H2 at ∼ 1400 °C have an increased laser performance. Mo admixture in hydrogen annealed YAP:Nd laser crystals suppresses effectively the detrimental action of iron impurity.

YAP:Nd crystals grown from the melt in molybdenum crucible under reducing (He-Ar-H2) protective atmosphere contain growth colour centre (brown appearance) due to surplus of metal ions. The colouration may be irreversibly removed by annealing at ≳ 1200 °C. Oxygen annealed crystals are improper as a laser active material because of colour centre formation (reddish appearance) which is substantially strenghtened by the pumping light. This phenomenon is connected with the presence of molybdenum (≳5 ppm) in a higher valence state. On the other hand the same crystals treated in vacuum or hydrogen need a limited filtration of the pumping light (up to 280–320 nm), to exclude detrimental role of iron impurity and they may be succesfully used in continuous and particularly in pulsed lasers. No ageing or erratic performance was found in the lasers using such crystals.

Spectroscopic properties of undoped YAG and YAP grown under reducing protective atmosphere were compared. Blue (with F centre) or brown (with 0 centre) varieties both of the materials were prepared in the dependence of the Al O :Y O ratio in the melt. Colour intensity depends on the H O:H ratio in the protective atmosphere and on the sign of electrical potential above the melt level. The coloration may be easily removed by an annealing at > 1200–1400 °C. All the irregularities of the colourations or their remowing by annealing may be attributed to the presence of impurities.