ALBERT

Description: Calcium carbonate in sediments can greatly effect the engineering properties of those sediments. Factors that may effect engineering properties are: 1) great variation in primary void ratios, (2) inherent strength of carbonate grains, (3) degree of sorting, (4) ratio between grains and matrix, (5) nature and amount of cement, and (6) depth of burial. Deep-sea carbonates appear to be anomalous but do exist in rather large quantities. Their existence must depend upon a combination of physico-chemical and organic-chemical factors that need to be investigated in much more detail.

Description: Mineral resources on and beneath the seafloor are briefly reviewed and the present and future economic value of specific mineral resources is discussed. The results obtained from the cruises of the German research vessel "Valdivia" during its first three years of operation are presented.

Description: The kinetics of methane hydrate decomposition was studied using a semibatch stirred-tank reactor. The decomposition was accomplished by reducing the pressure on a hydrate slurry in water to a value below the three-phase equilibrium pressure at the reactor temperature. The data were obtained at temperatures from 274 to 283 K and pressures from 0.17 to 6.97 MPa. The stirring rates were high enough to eliminate mass-transfer effects. Analysis of the data indicated that the decomposition rate was proportional to the particle surface area and to the difference in the fugacity of methane at the equilibrium pressure and the decomposition pressure. The proportionality constant showed an Arrhenius temperature dependence. An estimate of the hydrate particle diameters in the experiments permitted the development of an intrinsic model for the kinetics of hydrate decomposition.

Description: Cephalopod remains were collected from all of 12 dead Emperor penguin chicks [Aptenodytes forsteri (Gray)], from 76% of 29 living adult Emperor penguins, and from 18% of 105 living adult Adelie penguins [Pygoscelis adeliae (Hombron & Jacquinot)] from Adelie Land, Antarctica, in 1982. Of the seven species of squids represented by lower beaks, Psychroteuthis glacialis comprised 88% of the number in both Emperor chicks and Emperor adults and 100% in Adelie adults. From estimates of the weight of squids represented by lower beaks, Gonatus antarcticus and Kondakovia longimana contributed 18 and 14%, respectively, of the weight of squids in the diet of Emperor chicks and 27 and 21%, respectively, in the diet of Emperor adults. The data suggest that Psychroteuthis glacialis probably hatch in July–September and grow steadily for one year, and then spawn and die.

Description: 1. Effects of noradrenaline and the related compounds adrenaline, dopamine, octopamine, tryamine, clonidine and isoprenaline were studied in isolated heart preparations from the cuttlefish Sepia officinalis L. 2. All analogues produced a positive inotropic affect, with noradrenaline being the most potent substance. The chronotropic effects of the tested compounds differed widely. 3. The action of substances of the phenylethanolamine group were not antagonized by propanolol but were partly antagonized by phentolamine. 4. Serotonin and its analogues also produced cardio-excitation. These effects were blocked by cyproheptadine but not by methysergide. 5. These results indicate the presence of two different receptors in the Sepia myocardium: one type reacting with noradrenaline most effectively and a second type being stimulated by serotonin.

Description: This chapter discusses the Maillard reaction. Results of the many investigations into the mechanism of the Maillard reaction support one of two main theories. The first assumes the formation of glycosylamines that undergo the Amadori (or, for ketoses, the Heyns) rearrangement. The 1-amino-l-deoxyketose derivative (or 2-amino-2-de- oxyaldose derivative) formed may be dehydrated and cyclized to form furan derivatives, or it may enolize. In either case, intermediates that are readily transformed into brown compounds are formed. A third possibility is for the deoxy sugar derivative to react with more amino acid to form colored products. The many workers who have supported this mechanism found also that optimum conditions for occurrence of the Maillard reaction are (1) fairly low water content, (2) a pH of 7 to 10, and (3) a high temperature. Nevertheless, some reaction occurs under conditions far removed from these, but in the absence of moisture there is no reaction. The formation of an acyclic Schiff base as an initial step is not very likely, since replacement of the aldose by salicylaldehyde caused only a very small loss of amino groups. The second theory of the mechanism of the browning reaction is of recent origin and maintains that the browning reaction and the Maillard reaction are separate and distinct. Browning, according to this school of thought, is due to the effect of pH on the sugar and can occur over a wide range of pH, whereas the Maillard reaction proceeds only in alkaline media.

Description: The Pantelleria Rift system is a wide zone of post-Miocene northwest-trending grabens and horsts beneath the Sicily Strait. The central grabens host volcanics of predominantly alkalic composition which are exposed on the islands of Pantelleria and Linosa. On the Maltese Islands, along the northeastern shoulder of the rift, an Oligocene-Miocene carbonate succession exposed above sea level allows structural analysis and determination of shallow crustal stresses within the otherwise largely submarine rift system. An older northeast-trending set of normal faults is probably the expression of an Oligocene-Miocene crustal extension event which produced continental rifts in western Europe and led to passive margin formation in the western Mediterranean. Younger northwest-trending grabens of the Pantelleria Rift system cut the older faults almost at right angles and define a zone of lithospheric stretching between Tunisia and Sicily. The northwest-trending grabens which subsided dramatically since the beginning of Pliocene time appear to be connected by east-trending dextral and, more rarely, north-trending sinistral transforms. Displacement along the transforms is probably in the order of a few kilometres. In-situ stress measurements carried out on the Maltese Islands show maximum horizontal compression (SH) parallel to the rift. This suggests that in general σ1 (vertical) and σ2 (horizontal and parallel to the rift) are of about the same magnitude; both exceed σ3 (Sh) which trends northeasterly. Slight intraplate convergence in a NW-SE direction seems to be more than balanced by extension in a NE-SW direction. Neotectonics of the region possibly reflects an asthenospheric flow pattern which became established during the Messinian salinity crisis. The mechanism of recent intraplate deformation of the Pelagian shelf has relevance for the understanding of more anciently subsided platforms of the Apulian Plate.