High mortality from cannibalism in crowded cultures of the noble crayfish (Astacus astacus L.) was the reason why the efforts for an intensive production of this species in the 1980s were largely stopped. In the present study, 14-to 15-month-old juveniles of A. astacus were cultured in tanks of an indoor recirculation system under constant 'summer conditions' (19°C, LD 16:8) from early August to late January. The animals continued to moult and grow, indicating that the absence of these processes in the field from autumn to late spring does not involve any endogenous programming. The experimental design (suitable hiding places in excess, highly diversified diet, and special daily and lunar light regimes) ensured high survival (>90%) and growth rates which were largely independent of stocking rate (15-60 individuals per m 2 ). Moulting occurred during daytime which allowed freshly moulted animals to escape from cannibalistic attacks of their nocturnal conspecifics. There is a first indication that an artificial moonlight cycle can synchronize moulting events (maximum around 'new moon'), in this way contributing to a further decrease in mortality. The results encourage a resumption of efforts for an intensive production of A. astacus in indoor recirculation systems.

Juvenile noble crayfish, Astacusastacus (Crustacea, Astacidea) in the second year of age were kept in the laboratory for a twelve-month period under continuing “summer conditions” (LD 16:8, 19°C). Molting processes in this population could be synchronized by artificial moonlight cycles. Peaks of exuviations occurred at “new moons”. Males showed a slightly higher degree of synchronization than females. A phase-shift of the artificial lunar cycle in relation to the natural cycle resulted in a corresponding shift of the molting cycle. This clearly demonstrates that changes in the nocturnal light regime provide the primary external information for the lunar-monthly molting rhythm. There is a first indication that lunar photic stimuli do not act directly but as a zeitgeber which entrains an endogenous molting rhythm to the lunar cycle. Moreover, the results of the long-term experiments suggest that the hibernal resting period of A . astacus in the field (no molts between October and April) may also involve some endogenous programming. Continuing artificial summer conditions can delay but not completely suppress this resting period. The adaptive significance of the phenomena and how the findings may be applied to improve the management of crowded crayfish stocks are discussed.

Tell 2: Einflull der thermischen Behandlung van zerkleinerten UF-gebundenen Span-und MDF-Platten sowie Kiefernsp~inen auf die Formaldehyd-und Ammoniakabgabe R. Franke, E. RoffaelIm Tell 1 der Arbeit (Franke und Roffael 1998) wurde fiber die Auswirkung der Thermohydrolyse yon UF-gebundenen Span-und MDF-Platten auf die Ausbeute, den Bindemittelabbau, den pH-Wert und den Pentosangehalt berichtet. Es wurde festgestellt, daft infolge der Thermohydrolyse der pH-Wert der w~isserigen Auszfige von Spanund MDF-Platten zunimmt und ihre Pufferkapazit~it gegen Alkali abnimmt. Ferner zeigte sich, daft die UF-Harze eine relativ hohe Hydrolyseresistenz aufweisen. In diesem Tell der Arbeit wurde die Formaldehydabgabe, ermittelt nach der WKI-Flaschen-Methode, bei unterschiedlichen thermischen Behandlungen der Proben untersucht. Weiterhin wurde der Einflufl der thermischen Behandlung yon zerkleinerten Platten auf die Ammoniakabgabe und den pHWert ermittelt. Zum Vergleich wurden Kiefernsp~ine aus Rundholz in die Untersuchungen einbezogen. On recycling of particle-and fibreboards (MDF) Part 2: Influence of thermal treatment of particles from UF-bonded particle-and MOF-boards as well as pine particles on the formaldehyde and ammonia releaseIn part 1 of the work (Franke and Roffael 1998) investigations were carried out on the influence of thermal hydrolysis of UF-bonded particle-and medium density fibreboards (MDF). The degradation of UF-resins was followed up, the change of the pH-value in the water extractives, the yield and the pentosan content of the lignocellulosic material were also assessed. Due to thermal hydrolysis the pH-value of water extractives increases and their alkaline buffering capacity decreases. Moreover, it was shown that UF-resins have a relatively high resistance towards hydrolysis. In this part of the work investigations were conducted on the formaldehyde release at different test temperatures. Further, the influence of thermal treatment of the disintegrated baords on the ammonia release was assessed. Moreover, the change of the pH-value of the extractives was determined. For comparison particles from round pinewood were included in the investigation. 1 Experimentelle ArbeitEs wurde je eine handelsfibliche, 19 mm dicke, unbeschichtete, gebrauchte, UF-gebundene Span-und MDFPlatte in einem schnell-rotierenden Brecher (electra industrie, Siebmaschenweite 15 mm) zerkleinert. Anschlie-

Teil 1: Uber die Hydrolyseresistenz yon ausgehiirteten Harnstoff-Formaldehydharzen (UF-Harzen) in Span-und mitteldichten Faserplatten (MDF) R. Franke, E. RoffaelDas Recycling yon Holzwerkstoffen hat in den letzten Jahren in Deutschland durch eine zunehmend strenger werdende Gesetzgebung immer mehr an Bedeutung gewonnen. Derzeit scheinen Verfahren, die auf dem Prinzip der Hydrolyse durch Dampfbehandlung basieren, das Interesse der Industrie zu wecken. In diesem Zusammenhang wird in dieser Arbeit untersucht, wie sich die Dampfhydrolyse yon UF-gebundenen Span-und MDF-Platten auf den Abbau des Bindemittels und den pH-Wert der Extrakte auswirkt. Ferner werden Ausbeute und Gehalt an Pentosan als Marl fiir den Abbau an Lignocellulosen ermittelt.Sandberg AG (1965) Verfahren zur Wiedergewinnung von Spanmaterial aus mit ausgehiirteten Bindemitteln durchsetzten Abfiillen, Siigesp/inen, Mull usw., zur Herstellung yon Spanplatten und ~hnlichen geleimten oder geprei]ten Erzeugnissen. DE-AS 12ol 045 Wagner K (1996) Das neue Regelwerk zum KrW-/AbfG, VDI Verlag, Dfisseldorf, ISBN 3-18-99ooz7-5

Perioperative hypothermia is frequent during thoracic surgery. After approval by the local ethics committee and written informed consent from patients, we examined the efficiency of prewarming and intraoperative warming with a convective warming system and conductive warming system to prevent perioperative hypothermia during video-assisted thoracic surgery (VATS). We randomized 60 patients with indication for VATS in two groups (convective warming with an underbody blanket vs. conductive warming with an underbody mattress and additional warming of the legs). All patients were prewarmed before induction of anesthesia with the corresponding system. Core temperature was measured sublingual and in the nasopharynx. Both groups were not significantly different in regard to clinical parameter, prewarming, and initial core temperature. The patients in conduction group had lower intraoperative core temperatures and a higher incidence of intraoperative (73.9 vs. 24%) and postoperative hypothermia (56.5 vs. 8%) compared with convective warming. Pre- and intraoperative convective warming with an underbody blanket prevents perioperative hypothermia during VATS better than conductive warming. The inferior prevention in conductive warming group may be caused by reduced body contact to the warming mattresses in lateral position.