On the taxonomy of South African digger wasps of the tribe Oxybelini (Hymenoptera,Crabronidae)

Three South African species of digger wasps of the tribe Oxybelini, initially described in the genus Belomicrus A. Costa, B. (Nototis) bicornutus Arnold, B. (Nototis) crassus Arnold, and B. ferrieri Kohl, are considered to be members of the separate genera Nototis Arnold, 1927, Belarnoldus gen. n., and Belokohlus gen. n., respectively. The new species Nototis falcidens and the previously unknown male of N. bicornutus and female of B. crassus are described. The lectotype of B. ferrieri is designated.     

A new species of digger wasps of the genus <Emphasis Type="Italic">Belomicroides</Emphasis> (Hymenoptera,Crabronidae, Oxybelini) from North Africa

The new species of digger wasps, Belomicroides rufus, is described from North Africa. The new species differs from the all members of the Belomicroides schmiedeknechtii species-group in the pale coloration and dense pubescence of the body.     

Carbon and Nitrogen Mineralization of Lead Treated Soils in the Eastern Mediterranean Region,Turkey

The aim of this study was to determine the first effect of lead on microbial activity in soil. The study was carried out in the soil samples from four different radish (Raphanus sativus L. var. radicula, Brassicaceae) fields along the highway in a district (Kadirli, Osmaniye) of the Eastern Mediterranean Region, Turkey. After the calculation of Pb contents, the Pb amounts of the soil samples were brought up to 50 and 100 mg Pb kg^?1 by treatment with Pb(NO ₃ ) ₂ , and the samples for the carbon and the nitrogen mineralization were incubated under controlled conditions (28°C, constant moist). The carbon mineralization was determined by a CO ₂ respiration method for 30 days. The nitrogen mineralization was observed in vitro for 6 weeks. The untreated group was statistically different from the 50 and 100 mg Pb kg^?1 treatments in the aspect of the C(CO ₂ ) outlet during mineralization (P ≤ 0.05), but difference between the 50 and 100 mg Pb kg^?1 treatments was not significant. NH ₄ -N and NO ₃ -N contents of each soil were shown differences between across treatments. Based on these results, it is possible to conclude that the addition of 50 and 100 mg Pb kg^?1 provided a toxic effect threshold for the microbial activity into 30 days.     

Incidence of mycoflora and mycotoxins in some edible fruits and seeds of forest origin

Twelve fungi namelyAlternaria alternata, Aspergillus flavus, A niger, A ochraceus, Actinomucor repens, Capnodoium spp., Curvularia lunata, Fusarium pallidoroseum, F solani, F verticillioides, Penicillium citrinum and Rhizopus stolonifer were recorded from samples ofAegle marmelos, Aesculus indica, Buchanania lanzan andPinus gerardiana. In case ofPrunus amygdalus only Rstolonifer was recorded. A significant variation in pattern of mycoflora incidence was observed in terms of source and season. Fungal infestation in most of the substrates was found to be highest during monsoon. Aflatoxins were the most common mycotoxins elaborated by different isolates ofA flavus obtained fromA marmelos, B lanzan andP gerardiana. The amount of aflatoxins produced by the toxigenic isolates ofA flavus was in the range of traces to 0.9–26.0 μg/ml inA marmelos, 0.8–17.5 μg/ml inP gerardiana and 0.65–13.2 μg/ml inB lanzan. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi. Aflatoxins were detected almost in all the samples analyzed for mycotoxin contamination. However, traces of zearalenone were detected inA marmelos. The concentration of aflatoxin B₁ was in the range of 0.13–0.75 μg/g inA marmelos, 0.09–0.60 μg/g inP gerardiana and 0.01–0.20 ug/g inB lanzan. Mycotoxins were not detected inAesculus indica andPrunus amygdalus.     

<Emphasis Type="Italic">Rovnoecus</Emphasis>, a new genus of digger wasps (Hymenoptera,Crabronidae, Pemphredoninae) from the Rovno amber

A new fossil digger wasp Rovnoecus klesovicus gen. et sp. nov. (Hymenoptera, Crabronidae, Pemphredoninae, Pemphredonini) is described from the Upper Eocene Rovno amber. The genus Rovnoecus gen. nov. is characterized by an incomplete occipital carina, partly reduced second discoidal cell, and the presence of spines on all tibiae. Rovnoecus gen. nov. is most similar to the fossil genus Eoxyloecus Budrys, 1993 from the Baltic amber. The two genera form a monophyletic group that is a sister group to the group formed by the genera Passaloecus Shuckard, 1837 and Eopinoecus Budrys, 1993. This indirectly corroborates the hypothesis of the geographically different origin of the Rovno and Baltic ambers.     

Physicomathematical model of plasma acceleration in an ablative pulsed plasma thruster

A new comparatively simple quasi-one-dimensional physicomathematical model of plasma acceleration in an ablative pulsed plasma thruster with a capacitive energy storage is proposed. In spite of its simplicity, the model adequately reflects the main physical processes occurring in the thruster channel in the course of plasma blob acceleration: the blob dynamics, plasma radiation, absorption of radiation by the Teflon channel walls, ablation of the wall material, and plasma ionization. The results of computer simulations agree well with the experimental results.