In this paper we describe and illustrate the nesting behaviour, egg and larvae of all three instars of Synapsis yunnanus Arrow 1933. Two nests of S. yunnanus were observed in Northern Yunnan, China. The nest is subterranean and paracoprid, with female present in the nest chamber after oviposition. The brood ball is covered with a compacted layer of soil, and the egg chamber is proximal, situated in dung. Six brood balls were found in each nest. Larvae are compared with the only other species known in larval stage, S. tmolus (Fischer von Waldheim 1821). We identify differences between individual larval instars of S. yunnanus and provide an identifi cation key to individual instars. Shape of anal plate of L3 found shortly after ecdysis is different from the plate of older larvae and therefore its value as differential character is limited. We also discuss the function of egg-bursters and the course of hatching, functions of the stipital "pars stridens" and of the raster on abdominal sternum X, and problems with the assessment of the generic diagnosis of Synapsis Bates 1868 larvae. Résumé. Stades immatures et nidifi cation de Synapsis yunnanus (Coleoptera : Scarabaeidae).Dans cet article, nous décrivons et illustrons la nidifi cation, l'oeuf et 3 stades larvaires de Synapsis yunnanus Arrow 1933. Deux nids de S. yunnanus ont été observés au nord du Yunnan, Chine. Le nid est souterrain et paracopride, avec la présence de la femelle dans la cavité après l'oviposition. La boulette du couvain est couverte d'une couche de terre compacte, la chambre de l'oeuf est proximale dans la bouse. Six boulettes ont été trouvées dans chaque nid. Les larves sont comparées avec la seule autre espèce connue au stade larvaire, S. tmolus (Fischer von Waldheim 1821). Nous indiquons les différences entre les différents stades larvaires de S. yunnanus et nous donnons une clé d'identifi cation des stades. La forme de la plaque anale du L3 trouvée juste après l'éclosion est différente de celle des larves plus vieilles et de ce fait, sa qualité diagnostique est limitée. Nous discutons aussi la fonction des "eggs bursters" et le déroulement de l'éclosion, les fonctions des "pars stridens" stipitales et du peigne du tergite abdominal X, ainsi que les caractéristiques génériques diagnostiques des larves de Synapsis Bates 1868.

One of the main problems in machining Al alloys represents built-up edge formation. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on built-up edge formation. Four variants of castings modified by strontium, calcium and antimony are used. All these alloys are compared with non-modified alloy. Built-up formation leads to the increasing of surface roughness for both types of built-up edge -unstable or stable. If unstable built-up edge is produced, surface roughness increases enormously. Therefore the research is focused on surface roughness in different cutting conditions. There were moulded castings of non-modified alloy and for each modified variant. Gravity-die castings into a metal mould with a thermal insulation were made.