Theoretical Study On The Reaction Mechanism Of Gecl3ch2ch2cooh+h2o→gecl2ohch2ch2cooh+hcl

The mechanism and dynamical properties for the title reaction have been investigated theoretically. Three reaction pathways have been found. Geometries, vibrational frequencies, infra-red (IR) intensities and relative energies for various stationary points in the three reaction channels have been determined respectively. The corresponding rate constants at the B3LYP/6-31++G(2d,2p) level have been deduced over a wide temperature range of 200–2000 K by using canonical variational transition state theory with small curvature tunnelling effect. Solvent effects are taken into account via the Onsager model of self-constant reaction field at the same level of theory. This preliminary study shows that the complex formation is favoured by the use of water solvent.     

Temporal processes and duck populations: examples from Mývatn

Studies of temporal processes at Lake Mývatn, Iceland, on three scales, millennial, centennial and decadal, are reviewed and a summary is presented of the main results of waterfowl population monitoring studies conducted during the past three decades. The characteristics of shallow, subarctic Lake Mývatn and its volcanic environment, are outlined, as well as recent conflicts between development and conservation. Mining of the bottom sediment of Lake Mývatn has been a major agent causing habitat destruction and damage to the food web. Population limitation of waterbirds at Mývatn is discussed, as three research questions and emerging answers: (1) How is reproductive output determined? All species studied showed positive correlations of production of young with levels of aquatic insects, catastrophic weather was rarely important; (2) How is the dispersion of breeding ducks determined? Densities of migratory species are determined mainly by resource levels on the breeding ground in the year before they return to the breeding area; a year-round resident species, Bucephala islandica, adjusts its density to the current availability of insect food in each of two main habitats used; (3) How are flyway populations of ducks determined? For most species, there is not enough information on total numbers and the state of the habitat on a flyway scale. In B. islandica, there are indications that the total population is limited by resources in winter. The Mývatn study area is dominated by a single, shallow and eutrophic lake and for many waterbird species the area seems to form a single functional unit. This leads to significant correlations when comparing demography with environmental conditions, such as food resources.     

Inheritance of some leaf characters inSalvia němecii HBý

Mezidruhový hybridSalvia němecii (S. nutans x 8. juri?i?ii), popsaný autorem ji? d?íve, je plně plodný. Proto byly na 238 rostlinách F₂ generace sledovány tyto znaky: typ svazk? cévních v 159;apíku, poměr délky ?apíku k délce ?epele, délko?í?kový index ?epele listové a ?lenitost ?epele, vyjád?ená poměrem ideální obrysové ploehy listu k jeho skute?né plo?e. V?ecky tyto charakteristiky srovnány se situací u rodi?ovských druh? i F₁ hybrida. Bylo zji?těno:

1. 1.
   Typ II svazk? cévních je jednodu?e a úplně dominantní nad typem III (?těpný poměr 172 : 66, X²(1) = 0.94, p =0–35).,