Beitrag zur Zeitstandfestigkeit von Chrom-Molybdän-Vanadin-Stählen für den Turbinenbau

Ergebnisse aus Zeitstandversuchen bis rd. 50000 h bei 500, 530 und 550°C an Proben aus dem Rand- und Kernbereich von 12 Turbinenwellen mit einem gröβten Vergütungsdurchmesser von 1190 mm aus Chrom-Molybdän-Vanadin-Stählen mit 0,21 bis 0,34% C, 1,06 bis 1,43% Cr, 0,56 bis 1,28% Mo, 0,09 bis 0,74% Ni und 0,17 bis 0,35% V sowie an Stabstahl Rd. 28 mm mit rd. 0,30% C, 1,15% Cr, 0,35% V und Molybdängehalten zwischen 0,11 und 1,15%.     

Lack of effect on ovariectomy on the metabolism of vitamin D and intestinal calcium-binding protein in female rats

A 20-year-old woman lost all useful vision over a 2 1/2-month period as a result of a necrotizing and occlusive vasculitis of the retina. Treatment with prednisone, immunosuppressants, and aspirin was unsuccessful. No systemic manifestations of the disease were found and no cause was discovered. Kodachromes and fluorescein angiograms showed the progression in one eye from normal to near total retinal necrosis. The process began with a mild venous dilation and peripheral arteritis that progressed into an obliterative vasculitis with abrupt vessel dilation, hemorrhages, and retinal swelling. This was followed by necrosis and sloughing of the retina into the vitreous. Vitreous contraction and necrotic retina produced unrepairable retinal detachments.     

Steep central islands after myopic photorefractive keratectomy

The nitric oxide synthase inhibitor 7-nitroindazole (7-NI) dose-dependently (3.0-30.0 mg/kg) displayed anxiolytic activity, as measured by an increase in open arm exploration time in the elevated plus-maze (EPM), following intraperitoneal (i.p.) administration in rats. Acute administration of 7-NI at 30.0 mg/kg significantly (P < 0.05) increased open arm exploration time by 176% compared to vehicle control, similar to the benzodiazepine diazepam at 1.0 and 3.0 mg/kg (+ 191 and + 200%, respectively). However, 39 h following subchronic 5-day administration of diazepam twice daily (bid) at 3.0 mg/kg, diazepam was devoid of anxiolytic activity at 1.0 mg/kg, as measured by no difference in open arm exploration time compared to vehicle control, while the 3.0 mg/kg dose still produced a significant (P < 0.05) 175% increase in open arm exploration time. In contrast, following subchronic administration of 7-NI (30.0 mg/kg, bid), a significant (P < 0.01) enhancement in open arm exploration time was observed at 30.0 mg/kg (+ 665% compared to control). Therefore, inhibition of nitric oxide synthase by 7-NI resulted in anxiolysis similar to diazepam following acute administration in the EPM. However, following subchronic administration, unlike diazepam which showed an attenuation of anxiolytic activity, 7-NI displayed enhanced anxiolytic efficacy and was devoid of tolerance.     

Lower time bounds for integer programming with two variables

In this paper an elementary version of the integer programming problem is considered, namely that of deciding whether a given triangle in the plane contains a point with integer coordinates. We prove two lower bounds for the number of operations necessary to solve this problem: (i) Ω(p) steps are necessary if operations from {+, -,%,, ?} are admissible, (ii) Ω(log p) steps are necessary if operations from {+, -, ?·?, ?} are admissible. Here, p denotes the binary length of the input and ?·? denotes the floor function. New techniques are necessary for relating the bounds to the length of the input—known methods only yield uniform bounds assuming all real inputs to be allowed—and for handling the floor function which prevents us from applying the well-known algebraic arguments.The best known algorithm is due to H.W. Lenstra, Jr. (preprint) and needs O(p) steps over {+, -, 1, %, ?·?, ?} (P. van Emde Boas, 1984).     

Über die Grundlagen der Warmfestigkeit,dargestellt an legierten Stählen

Darstellung der bei reinen Metallen sowie homogen und heterogen aufgebauten Legierungen das Kriechverhalten bestimmenden Vorgänge. Übertragung der Modellvorstellungen auf die Gegebenheiten bei warmfesten Stählen. Zusammenhang zwischen dem Werkstoffaufbau (Gefüge, Ausscheidungszustand) und den Langzeit-Festigkeitseigenschaften legierter Stähle mit Chrom und Molybdän sowie Chrom, Molybdän und Vanadin.     

Synthesis and antiapoptotic activity of a novel analogue of the neutral sphingomyelinase inhibitor scyphostatin

The enantioselective synthesis of an analogue of scyphostatin, a potent inhibitor of the neutral sphingomyelinase, is described. The synthesis starts with cyclohexanone and a protected D-serine derivative. The key step is an asymmetric hydroxylation to access a hydroxycyclohexanone, which is transformed into a substituted hydroxycyclohexenone. This is converted into the scyphostatin analogue 14, a chemically and metabolically stabilised compound lacking the epoxy function of the natural congener and carrying a palmitic acid group instead of the native trienoyl residue. An evaluation of the biological activity of 14 revealed neutral sphingomyelinase inhibition in several in vivo test systems (monocytes, macrophages, hepatocytes) monitoring antiapoptotic effects and the inversion of phorbolester-induced translocation of green fluorescent protein labelled kinase (protein kinase C-alpha).     

8-channel optical demultiplexer realized as SiO2/Siflat-field spectrograph

The operation of a flat-field spectrograph in silica on silicon (SiO₂/Si) for 2-nm channel spacing is demonstrated. Crosstalk attenuations of >20 dB and significantly reduced fiber-to-fiber insertion losses of 5 dB could be obtained     

Locating illicit connections in storm water sewers using fiber-optic distributed temperature sensing

A newly developed technique using distributed temperature sensing (DTS) has been developed to find illicit household sewage connections to storm water systems in the Netherlands. DTS allows for the accurate measurement of temperature along a fiber-optic cable, with high spatial (2 m) and temporal (30 s) resolution. We inserted a fiber-optic cable of 1300 m in two storm water drains. At certain locations, significant temperature differences with an intermittent character were measured, indicating inflow of water that was not storm water. In all cases, we found that foul water from households or companies entered the storm water system through an illicit sewage connection. The method of using temperature differences for illicit connection detection in storm water networks is discussed. The technique of using fiber-optic cables for distributed temperature sensing is explained in detail. The DTS method is a reliable, inexpensive and practically feasible method to detect illicit connections to storm water systems, which does not require access to private property.     

A+C群脑膜炎球菌多糖疫苗大规模接种后的速发型接种反应观察

目的观察A+C群脑膜炎球菌多糖疫苗大规模接种后的速发接种反应。方法以A+C群脑膜炎球菌多糖疫苗为观察组,伤寒Vi多糖疫苗为对照组,按组群随机分层配对的原则,将观察现场分为108个组群,观察组和对照组各分配54个组群进行接种。建立接种反应监测系统,按统一表格和方法对两组的速发接种反应进行监测。结果两组共接种34 543人,其中A+C群脑膜炎球菌多糖疫苗接种18 167人,伤寒Vi多糖疫苗接种16 376人。A+C群脑膜炎球菌多糖疫苗速发接种反应率为0.44‰;伤寒Vi多糖疫苗速发接种反应率为0.79‰,二者差异无统计学意义;速发接种反应均出现在接种后15 min内,最早的出现在接种后5 min,速发接种反应中有2例为异常反应,但未出现严重反应。结论A+C群脑膜炎球菌多糖疫苗速发接种反应发生率低,预后良好。