Species-area effect

No apparent correlation between number of species and biogeographic unit size (compare, for example, units D and A) has been identified. Even if not formally tested, this seems to contradict the species/area effect (see Gaston and Blackburn, 2000). However, this relationship is not explored in detail here because unit size/area is difficult to quantify cuttlefishes live near the bottom of the sea, so the biogeographic size unit measure would have to be based more on the effective available surface... 

Throughout the studies discussed in this review there persist a number of questions of so fundamental a nature as to preclude much further progress in the field before additional insight is available. These involve areas in which decisive experiments have not yet been done, and in which such experiments appear to be either very difficult or totally impossible. These questions arise What is the nature of the starting species What effects result from reactions extraneous to the radiochemical phenomenon— adsorption, exchange, etc. At what stage following the nuclear event do the observed chemical reactions occur ... 

Both lantana and common purslane are weed pests in some crops. Common purslane root exudates inhibited soybean growth but showed stimulation in other bioassays reported in this paper. This may be a concentration and bioassay species dependent effect, since the effect of any toxin varies according to concentration and bloassay species (12). Lantana root exudates showed the strongest inhibitory effect on soybean growth of any of the species tested. Lantana is not found in soybean fields but is a weed pest in some areas in citrus orchards. Holm (13) included lantana, johnsongrass, and cogongrass in his list of the worst weed pests in the world. 

The use of fossil fuels to supply energy for the use of the world s population has resulted in the release to the atmosphere of troublesome chemical byproducts that present harm to humans and other natural species. These effects can be localized (near the emission source), can extend to large regional areas (involving subcontinents), and can even cover the globe, from pole to pole. A large portion of the human population is exposed to one or more of these environmental effects. 

Although reactions of hypophosphorous acid with aqueous solutions of RuX3 (X = Cl, Br, I) are claimed to give RuX in situ,22 2 further work in this area is now required. More recently, Ru1 chloro compounds of possible formula H[Ru2Cl3(DMA)2] have been isolated from reaction of RuC13 x-H20 with H2 in DMA these species are effective catalysts for hydrogenation of alkenes and unsaturated carboxylic acids.2283... 

At low ultrasound intensities, bubble growth primarily occurs via rectified diffusion, which is the unequal mass transfer of species into the bubble during rarefaction and compression cycles. This phenomenon was first recognized by Harvey et al. during their experiments on animals, and Leighton has recently expounded on a well established theory that describes rectified diffusion in terms of an area effect and a shell effect. These two effects derive directly from basic mass transfer principles, which demonstrate that the rate of mass transfer is directly related to the surface area across which transfer can occur and the concentration (or more exactly, chemical potential) driving force. 

The area effect can be described by the following. During rarefaction, when the bubble expands, concentrations and pressure inside the bubble decrease, and so dissolved gases and other volatile species diffuse from the liquid into the bubble. However, bubble compression yields high pressure and concentrations inside the bubble, which causes gas to diffuse from the... 

The past year was marked by relatively little activity in this area, -Wadke and Guttman reported on the base induced degradation of 9-methylisoalloxazine under both aerobic and anaerobic conditions. The initial product formed appears to be a carbinol amine. Finholt et al have continued their investigation of anaerobic hydrolytic degradations of ascorbic acid with a study on the effect of metallic ions on the over-all rate. Although the reaction appears to be accelerated by doubly and triply charged species, the effect was surprisingly small. 

Quantitative measurement of the photophysics of the dissolved organic chromophores found In natural water Is needed to better understand the rates of energy transfer from their excited states and to provide Information as to the kinetics of excited state reactions they may undergo. Specific areas of Interest In natural water chemistry are the kinetics of quenching Interactions and energy transfer processes to other chemical species the effect of such Interactions on the Initiation of secondary photochemical reactions is particularly Important ( ). 

Another aspect of surface area effects deals with the poisoning of catalytically active sites by competing adsorbates. The species most pertinent to... 

---