III. Buchbesprechungen

Ohne Zusammenfassung     

Controlling the charge state of individual gold adatoms

The nature and control of individual metal atoms on insulators are of great importance in emerging atomic-scale technologies. Individual gold atoms on an ultrathin insulating sodium chloride film supported by a copper surface exhibit two different charge states, which are stabilized by the large ionic polarizability of the film. The charge state and associated physical and chemical properties such as diffusion can be controlled by adding or removing a single electron to or from the adatom with a scanning tunneling microscope tip. The simple physical mechanism behind the charge bistability in this case suggests that this is a common phenomenon for adsorbates on polar insulating films.     

Applications, complications, and outcomes of transvenous pacemaker implantation in 105 dogs (1997-2002)

We reviewed the indications for age and breeds of dogs who received transvenous endocardial artificial pacemaker (AP) implantation (n = 105) and complications and survival thereafter at a single institution over a 6-year period. A third-degree atrioventricular (AV) block (59%) and sick sinus syndrome (SSS; 27%) were the most common indications, along with a high-grade second-degree AV block (9%) and atrial standstill (5%). The most common breeds identified were Labrador Retriever (n = 16; 11 with a third-degree AV block), American Cocker Spaniel (n = 14; 10 with SSS), and Miniature Schnauzer (n = 13; all with SSS). Common presenting complaints were syncope (n = 66) and exercise intolerance or lethargy (n = 25). Half of the dogs (n = 52) had a history of acute onset of clinical signs (<2 weeks). Mean survival time for the 60 dogs who died during the study period was 2.2 years (range, 0.1-5.8 years). Major complications occurred in 13% of dogs and included lead displacement (n = 7), sensing problems that led to syncope (n = 3), infection at the pacemaker site (n = 1), bleeding (n = 1), and ventricular fibrillation during implantation (n = 1; successfully defibrillated). Minor complications occurred in 11 dogs (11%). The success rate of transvenous AP implantation was comparatively high (all dogs survived the first 48 hours), and the complication rate was comparatively low when compared with a previous multicenter study, most likely because of how commonly the procedure was performed and supervisory experience.     

Untersuchungen zum gezielten Einsatz von Insektiziden gegen den Rapsglanzkäfer (<Emphasis Type="Italic">Meligethes aeneus</Emphasis>) in der landwirtschaftlichen Praxis des Landes Brandenburg im Zeitraum von 2006 bis 2014

Before 2006, agents of class II pyrethroids were used to control rape pests including the rape pollen beetle mainly. Thus, the selection of pyrethroids-resistant pollen beetle populations was encouraged. The aim of our study was to identify ways to combat these populations. Therefore, data of 465 real on-farm insecticide applications from nine years since 2006 were analyzed with regard to their effects on the pollen beetle and own experiments were carried out to test the efficacy of approved insecticides and control strategies. The analysis showed that the highest efficiencies were obtained with agents of the group of organophosphates and with the active substances indoxacarb and pymetrozine. Beyond that, the data examined revealed that the efficiency of thiacloprid (an insecticide of the class of neonicotinoids) has remained relatively constant throughout the observation period. In contrast, the increase in pyrethroid-resistant pollen beetle populations reflects the further decrease in efficacy of class II pyrethroids in the period 2011–2014.In summary, it should be noted that currently available insecticides achieve a maximal abatement level of 80–85?%. Therefore, an economic damage cannot be prevented on rapeseed locations with a very strong pollen beetle infestation even if multiple use of insecticides happens.To prevent further escalation of the resistance problem, another aspect should be given greater attention in the future. 55?% of the insecticide applications in the practice dataset where carried out before the control threshold (BRW) for weakly developed oilseed rape crops was achieved; often in the stage of micro-bud (BBCH 51). In compliance with the currently suggested higher control threshold, only 15?% of the insecticide applications would have been necessary. Thus, a reduction of the number of insecticide applications could be achieved by considering the higher thresholds. This would significantly reduce the selection pressure. Therefore, plant protection advice should mediate between exploiting the control thresholds and using the most appropriate insecticide.     

Synthesis and Antiproliferative Activity of 2,5-bis(3′-Indolyl)pyrroles,Analogues of the Marine Alkaloid Nortopsentin

2,5-bis(3′-Indolyl)pyrroles, analogues of the marine alkaloid nortopsentin, were conveniently prepared through a three step procedure in good overall yields. Derivatives 1a and 1b exhibited concentration-dependent antitumor activity towards a panel of 42 human tumor cell lines with mean IC₅₀ values of 1.54 μM and 0.67 μM, respectively. Investigating human tumor xenografts in an ex-vivo clonogenic assay revealed selective antitumor activity, whereas sensitive tumor models were scattered among various tumor histotypes.     

Bestand,Umwandlung und Neubildung von Tonmineralen in küstennahen Sedimenten der Nordsee

Content, Transformation and Neoformation of Clay Minerals in near shore Sediments of the North Sea From literature and our own results, approximate quantitative values are given on the mineral content of clay and silt fractions of marine sediments from the Wadden Sea. Besides this, the extent of clay mineral transformation and neoformation in a marine environment is discussed. According to our knowledge, the extent of clay mineral transformation and neoformation must be unimportant because the sea water and pore solution of the sediments seems to be - with the exception of a small Mg-surplus — something like an equilibrium solution for three-and fourlayer minerals, which neither favors a considerable base fixation nor base release. Therefore illite neoformation during halmyrolysis or early diagenesis seems to be impossible because of unfavourable relations of potassium to all other cations in the sea water. Obviously the neoformation of illite is connected with later diagenesis. The processes of clay mineral neoformation in a marine evironment are probably restricted to the formation of amorphous (Mg-) Fe-Si-particles, which may be first steps in the formation of chamosites, chlorites or smectites.     

Einfluß einiger Klima- und Anbaufaktoren auf die Ertragsbildung der Reissorte ‘IR-8’ in Cuba II. Standweite und CO2-Assimilation

Zusammenfassung Infrarot-Gasanalyse bei der Reissorte IR-8 in Cuba bestätigte deren starke Heterogenität in der Photosynthesekapazität: Trotz gleicher Beleuchtungsstärke übertrifft die CO₂- Assimilation (je Blattflächeneinheit) in den obersten Blättern um ein Mehrfaches die der unteren Blätter.Im Pflanzenbestand übernehmen die obersten, gut mit Licht versorgten Blätter den Hauptanteil an der Stoffproduktion. Die steil aufgerichteten Fahnenblätter werden auch im dichten Bestand nicht gegenseitig beschattet und behalten ihre Photosynthese-Aktivität fast unvermindert bis zur Kornreife bei. Unterschiedliche Standweite hatte keinen Einfluß auf die einheitliche CO₂-Assimilation der Fahnenblätter.Starke Bewölkung und Regen können die Netto-Assimilation bis auf den Lichtkompensationspunkt senken und teilweise zu negativer Stoffbilanz in den Blättern führen.

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Effect of some climatic and agricultural factors on yield formation by the rice variety IR-8 in Cuba. II. Population density and nitrogen fertilization

Summary Infrared gas analysis with the rice variety IR-8 in Cuba confirmed the strong heterogeneity of photosynthesis; With equal light intensity, CO₂, net assimilation (per unit leaf area) proved to be much higher in the upper leaves than in the lower ones.Within the rice population, the upper leaves, well provided with light energy, assume the main share for dry matter production. Due to their upright position, the flag-leaves maintain high photosynthetic rates up to grain maturity, without mutual shading. Different levels of population density did not affect their uniform assimilation rate.Heavy clouds and rainfall may diminish net assimilation down to the light compensation point, and even may cause negative balance in dry matter production of the leaves.

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IR-8 . II. CO₂

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