The pea (Pisum sativum L.) genes sym33 and sym40 control infection thread formation and root nodule function

Two novel non-allelic mutants that were unable to fix nitrogen (Fix ) were obtained after EMS (ethyl methyl sulfonate) mutagenesis of pea (Pisum sativum L.). Both mutants, SGEFix(-)-1) and SGEFix(-)-2, form two types of nodules: SGEFix(-)-1 forms numerous white and some pink nodules, while mutant SGEFix(-)-2 forms white nodules with a dark pit at the distal end and also some pinkish nodules. Both mutations are monogenic and recessive. In both lines the manifestation of the mutant phenotype is associated with the root genotype. White nodules of SGEFix(-)-1 are characterised by hypertrophied infection threads and infection droplets, mass endocytosis of bacteria, abnormal morphological differentiation of bacteroids, and premature degradation of nodule symbiotic structures. The structure of the pink nodules of SGEFix(-)-1 does not differ from that of the parental line, SGE. White nodules of SGEFix(-)-2 are characterised by "locked" infection threads surrounded with abnormally thick plant cell walls. In these nodules there is no endocytosis of bacteria into host-cell cytoplasm. The pinkish nodules of SGEFix(-)-2 are characterised by virtually undifferentiated bacteroids and premature degradation of nodule tissues. Thus, the novel pea symbiotic genes, synm40 and sym33, identified after complementation analysis in SGEFix(-)-1 and SGEFix(-)-2 lines, respectively, control early nodule developmental stages connected with infection thread formation and function.     

Chrysotile asbestos in Russia: certain results and promising research directions

The article summarizes studies carried in RAMSc Research Institute for Occupational Medicine on chrysotile asbestos. Not denying potential carcinogenicity characteristic for all kinds of asbestos, those studies stress low biologic aggression of chrysotile asbestos during occupational exposure, even if the excessive MAC is demonstrated formerly in asbestos industry enterprises. Work with chrysotile asbestos, as every one in mining industry, requires not ban, but accomplishment of proper measures aimed to prevent pneumoconiosis and dust bronchitis. The article demonstrates unique experience of Russian scientists--evaluation of exposure to chrysotile without admixtures and amphibole additives. The authors define prospective research trends that, if being international, could correctly solve problems associated with further use of chrysotile asbestos, rising no "anti-asbestos" boom.     

An analysis of the polarization component of the measurement error in heterodyne laser interferometer measurement systems

The reasons for the occurrence of the polarization component of the measurement error in heterodyne laser interferometer measuring systems are considered. An analysis of this component is given.     

Mathematical modeling of gas combustion in a twisted jet and of the formation of a fiery whirlwind

Numerical simulation of fiery whirlwinds originating as a result of blowing-in of a twisted flow of a fuel gas into an initially stagnant medium is carried out. The results of calculations agree with experimental values in the entire range of twistings studied.     

Wet Etching Study of La0.67(Sr0.5Ca0.5)0.33MnO3 Films on Silicon Substrates

Wet etching of colossal magnetoresistive (CMR) perovskite La_0.67(Sr_0.5 Ca_0.5)_0.33MnO₃ (LSCMO) films on Bi₄Ti₃O₁₂/CeO₂/yttrium-stabilized zirconia (YSZ)-buffered Si substrates was investigated using potassium hydroxide (KOH) and buffered hydrofluoric acid (BHF) solutions. X-ray diffraction (XRD) and scanning spreading resistance microscopy (SSRM) measurements revealed that the morphological roughness of the LSCMO films increases, while the electrical resistance roughness decreases, with increasing KOH etching time. The LSCMO films are highly chemically resistant to KOH solution; however, in the case of BHF etching, an etch rate of 22 nm/min was obtained with high selectivity over a photoresist mask.     

Techniques for EPR spectroscopy of pulsed electron double resonance (PELDOR): A review

Techniques for electron paramagnetic resonance (EPR) spectroscopy of pulsed electron double resonance (PELDOR) are reviewed, and the features of the EPR spectroscopy procedure are considered. Basic theoretical results demonstrating the capabilities of the method in investigating paramagnetic particles are presented. It is shown that distances between paramagnetic particles in chaotically oriented systems—pairs and supramolecular ensembles—can be determined in the range of 1.5–8.0 nm. By analyzing the kinetics of the PELDOR signal decay, it is possible, apart from the distance, to determine the distance distribution function, mutual orientation of particles, and number of paramagnetic particles in formation of aggregates. A general block diagram of the PELDOR spectrometer, as well as cm- and mm-wave band spectrometers available in Russian and foreign laboratories, is described. The PELDOR sensitivity and resolution are discussed, and the range of distances measurable using this method is determined. Methods and procedures for determining the experimental parameters used to interpret the kinetics of PELDOR signal decay and estimate the structural parameters of a system of paramagnetic centers under investigation are considered. The PELDOR method with a magnetic field jump is described. The PELDOR technique and its advantages and drawbacks are analyzed in comparison with other methods for determining distances.