Comparative constructions of similarity in Northern Samoyedic languages

The purpose of this paper is to analyze the suffixes which are used in Northern Samoyedic languages to build comparative constructions of equality. Depending on the language, the suffixes may perform three functions: word-building, form-building, and inflectional. When they mark the noun, they serve as simulative suffixes and are employed to build object comparison. In the inflectional function, these suffixes mark the verb and are a means of constructing situational comparison. In this case, they signal the formation of a special mood termed the Approximative. This paper provides a detailed description of the Approximative from paradigmatic and syntagmatic perspectives

Exciton Description of Chlorosome to Baseplate Excitation Energy Transfer in Filamentous Anoxygenic Phototrophs and Green Sulfur Bacteria

A description of intra-chlorosome and from chlorosome to baseplate excitation energy transfer in green sulfur bacteria and in filamentous anoxygenic phototrophs is presented. Various shapes and sizes, single and multiwalled tubes, cylindrical spirals and lamellae of the antenna elements mimicking pigment organization in chlorosomes were generated by using molecular mechanics calculations, and the absorption, LD, and CD spectra of these were predicted by using exciton theory. Calculated absorption and LD spectra were similar for all modeled antenna structures; on the contrary, CD spectra turned out to be sensitive to the size and pigment orientations in the antenna. It was observed that, bringing two tubular antennae at close enough interaction distance, the exciton density of the lowest energy state became localized on pigments facing each other in the antenna dimer. Calculations predicted for stacked tubular antenna elements extremely fast, faster than 500 fs, intra-chlorosome energy transfer toward the baseplates in the direction perpendicular to the chlorosome long axis. Downhill excitation energy transfer according to our model is driven by interactions of the antennae with their immediate surroundings. Energy transfer from the chlorosome to the baseplate, consisting of 2D lattices of monomeric and dimeric bacteriochlorophyll <i>a</i> molecules, was predicted to occur in 5–15 ps, in agreement with experimental findings. Advancement of excitation through a double tube antenna stack, a model for antenna element organization in chlorosomes of green sulfur bacteria, to a monomeric baseplate was visualized in space and in time

Red Spectral Forms of Chlorophylls in Green Plant PSI- A Site-Selective and High-Pressure Spectroscopy Study

One of the special spectroscopic characteristics of photosystem I (PSI) complexes is that they possess absorption and emission bands at lower energy than those of the reaction center. In this paper, the red pigment pools of PSI-200, PSI-core, and LHCI complex from Arabidopsis thaliana have been characterized at low temperatures by means of spectrally selective (hole-burning and fluorescence line-narrowing) and high-pressure spectroscopic techniques. It was shown that the green plant PSI-200 complex has at least three red pigment pools, from which two are located in the PSI-core and one, in the peripheral light-harvesting complex I (LHCI). All of the red pigment pools are characterized by strong electron-phonon coupling. A Huang-Rhys factor of 2.9 found for the red pigments of LHCI is the largest found for any photosynthetic antenna system. This contrasts with the bulk pigments in the main Qy absorption band of chlorophyll a pigments for which the Huang-Rhys factors of less than unity are observed. This electron-phonon coupling difference of the red and bulk pigments is well reflected by the spectral dependence of the hole-burning efficiency, which is significantly reduced in the red absorption region. As a result of extremely low hole-burning efficiency in the red absorption band of LHCI, the hole-burning spectra of the PSI-200 complex mainly originate from the red pigments of the PSI-core complex. At the same time, the source of the red emission in PSI-200 is the red pigments of LHCI, in agreement with previous studies. The hole-burning spectra of PSI-core complexes from green plant and cyanobacteria are similar, both in red and bulk absorption regions. High-pressure spectroscopy data reveal dramatically larger pressure-induced linear shift rates for the redmost absorption and emission bands relative to those of bulk absorption bands. This is interpreted as due mostly to increased conformational mixing between the locally excited and charge transfer configurations of the red pigment aggregates. On the basis of analysis of available experimental data, we suggest that pigment dimers are probably responsible for the redmost states. Consequently, the excited red states can be interpreted as excimer states

Evidence for two spectroscopically different dimers of light-harvesting complex I from green plants

A preparation consisting of isolated dimeric peripheral antenna complexes from green plant photosystem I (light-harvesting complex I or LHCI) has been characterized by means of (polarized) steady-state absorption and fluorescence spectroscopy at low temperatures. We show that this preparation can be described reasonably well by a mixture of two types of dimers. In the first dimer about 10% of all Q(y) absorption of the chlorophylls arises from two chlorophylls with absorption and emission maxima at about 711 and 733 nm, respectively, whereas in the second about 10% of the absorption arises from two chlorophylls with absorption and emission maxima at about 693 and 702 nm, respectively. The remaining chlorophylls show spectroscopic properties comparable to those of the related peripheral antenna complexes of photosystem II. We attribute the first dimer to a heterodimer of the Lhca1 and Lhca4 proteins and the second to a hetero- or homodimer of the Lhca2 and/or Lhca3 proteins. We suggest that the chlorophylls responsible for the 733 nm emission (F-730) and 702 nm emission (F-702) are excitonically coupled dimers and that F-730 originates from one of the strongest coupled pair of chlorophylls observed in nature