The Structural Arrangement and Relative Abundance of Aliphatic Units May Effect Long-Wave Absorbance of Natural Organic Matter as Revealed by 1H NMR Spectroscopy.

The objective of this study was to shed light on structural features which underlay intensity of long wave absorbance of natural organic matter (NOM) using 1H NMR spectroscopy. For this purpose, a set of the NOM samples was assembled from arctic and nonarctic sampling sites (the Kolyma river basin and Moscow region, respectively). It was to ensure a substantial difference in the humification degree of the isolated organic matter-the biogeochemical proxy of the long-wave absorbance of NOM. The assembled NOM set was analyzed using solution-state 1H NMR spectroscopy. The distribution of both backbone and exchangeable protons was determined using acquisition of spectra in three different solvents. The substantially higher contribution of nonfunctionalized aliphatic moieties CHn (e.g., materials derived from linear terpenoids, MDLT) in the arctic NOM samples was revealed as compared to the nonarctic ones. The latter were characterized with the higher content of CHα protons adjacent to electron-withdrawing groups which belong to carboxyl rich alicyclic moieties (CRAMs) or to aromatic constituents of NOM. We have calculated a ratio of CHn to CHα protons as a structural descriptor which showed significant inverse correlation to intensity of long wave absorbance assessed with a use of E4/ E6 ratio and the slope of absorption spectrum. The steric hindrance of aromatic chromophoric groups of the NOM ensemble by bulky nonfunctionalized aliphatic moieties (e.g., MDLT) was set as a hypothesis for explanation of this phenomenon. The bulky aliphatics might increase a distance between the interacting groups resulting in inhibition of electronic (e.g., charge-transfer) interactions in the NOM ensemble. The obtained relationships were further explored using Fourier transform mass spectrometry as complementary technique to 1H NMR spectroscopy. The data obtained on correlation of molecular composition of NOM with 1H NMR data and optical properties were very supportive of our hypothesis that capabilities of NOM ensemble of charge transfer interactions can be dependent on structural arrangement and relative abundance of nonabsorbing aliphatic moieties.

[Transformation of humic substances of highly oxidized brown coal by the basidiomycetes fungi Trametes hirsuta and Trametes maxima].

The ability of the white rot basidiomycetes Trametes hirsuta and Trametes maxima to transform coal humic substances (HS's) under the conditions of solid phase cultivation in the presence or absence of an easily available source of corbon (glucose) has been studied. It was shown that during the growth of the fungal strains used in media, containing HS's, destructive and condensation processes of HS transformation proceeded simultaneously. Based on a comparative physicochemical analysis of the initial HS's and HS's transformed by the fungi, it was established that, despite the introduction of glucose may favor a deeper transformation of HS's by basidiomycetes, the general direction of their modification is dominant reduction or oxidation and is determined by the physiological biochemical peculiarities of the strain used.

[Bioacoustic characteristics of echolocation system of the long-eared European bat Barbastella barbastella]. / Bioakusticheskie kharakteristiki ékholokatsionnoi sistemy evropeiskoi shirokoushki (Barbastella barbastella).

Experimental data on the echolocation system parameters of Barbastella barbastella are reported. They include the parameters of orientation pulses, auditory frequency-threshold curves and characteristics of reception directionality of the external ear. It is demonstrated that the hearing system of this bat species has two hypersensitivity regions, which are tuned to the frequency components of the location call. Spatial diagrams of reception directionality have a complicated frequency-dependent configuration. Using the data obtained the authors consider possible mechanism of target direction finding.

[Physiologic mechanisms of use of the Doppler effect in echolocation by Rhinolophus ferrumequinum bats]. / Fiziologicheskie mekhanizmy ispol'zovaniia éffekta Dopplera v ékholokatsii letuchikh myshei Rhinolophus ferrumequinum

During the flight, the greater horse-shoe bat R. ferrumequinum decreases the frequency in the medial part of the emmited signal in proportion to the relative target--bat velocity. The value of the decrease is approximately equal to the Doppler shift; as a result, the animal picks up the echo at its species specific frequency irrespectively of the flight velocity. Threshold curve of bat's auditory system plotted in terms of N4, exhibits a sharp turning peak with a slope of about 83 dB/kHz towards low frequencies. The species specific frequency lies between the frequencies corresponding to the highest and the lowest thresholds. The described peculiarities of emission and perception of signals allow to consider the orientation system in the bat as a Doppler compensating system which provides the effective detection and discrimination of moving targets (e.g., a prey), improves spatial characteristics of hearing and enables the animal to evaluate the velocity during approaching the target.