Luminescence evidence for bulk and surface excitons in free xenon clusters

Cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying initial experimental parameters, including xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters (about 1500 atoms). The cluster size and temperature (about 40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. A presence of an argon shell causes extinction of the excitonic bands. In addition, some new bands were found which have no analogs for bulk xenon cryosamples.Comment: The final modified version will be published in Phys. Rev. A 76 (2007

Structural And Extremal Properties of the Hot Rolling Batches Precedence Graph

In this paper we study structural properties and properties of maximal paths of the hot rolling batches precedence graph. The hot rolling batches precedence graph arises in the problem of planning and scheduling of a hot strip mill load. Slab batches are selected and sequenced in turns. Basic technological restrictions on batch sequencing in turns are represented by the rolling batches precedence graph. Some fundamental structural properties of this graphs are stated such as the local block structure and the maximal paths structure. Motivation and overview of the result application potential are also provided

Mineral composition of bread wheat lines with introgressions of alien genetic material

Background. Modern bread wheat (Triticum aestivum L.) cultivars developed mainly to increase productivity often contain low concentrations of minerals in their grain. Wild and primitive wheats demonstrate rich genetic diversity, including the content of minerals in the grain, and can be used to improve the wheat gene pool for this trait. The aim of this work was to study the mineral composition in the grain of bread wheat lines with introgressions of the genetic material from Triticum L. spp.Materials and methods. We studied parental spring bread wheat cultivars, accessions of tetraploid and hexaploid Triticum spp., and 20 introgressive lines obtained on their basis in 2018 and 2020. Concentrations of macro- (K, P, Ca, and Mg) and micronutrients (Zn, Fe, Cu, and Mn) were measured using atomic emission spectrometry with inductively coupled plasma, and total protein content in wheat grain according to GOST 10846-91. The data were processed using the Statistica 10.0 and MS Excel software packages.Results and conclusion. The content of minerals in the grain of Triticum spp. was higher than in T. aestivum cultivars (the twoyear average difference was 1,02 to 2,13-fold, depending on the studied mineral). Most of the lines with alien genetic material exceeded their parent bread wheat cultivars in Zn, Fe, Cu and Mn content and came close to them in the levels of N, P, Mg and K. ANOVA established a statistically significant impact of the genotype, environment, and genotype × environment interaction on the variation of the grain macro- and micronutrient content. Lines with a consistently high concentration of grain minerals and high productivity were identified. These lines are of interest for wheat breeding for grain quality

SSR loci potentially associated with high amylopectine content in maize kernel endosperm

As a component of functional nutrition, maize cultivars with “non-traditional” kernel composition (waxy, oilbearing, sugar, opaque, etc. phenotypic variants) are promising. Mutations in the waxy gene, which break down the structure and function of the enzyme for amylose biosynthesis, lead to a waxy (with a high content of amylopectin) endosperm formation. High variability of the waxy gene limits the use of microsatellite loci in marker associated selection of waxy maize genotypes. The increased frequency of gene rearrangements within the waxy locus facilitated the origination of many high-amylopectin corn lines carrying different SSR allelic variants. The purpose of this study was to evaluate the effectiveness of using waxy locus microsatellite sequences for identification and labeling of waxy maize genotypes. To this end, a complex of biochemical (calorimetry, bichromate method), molecular-genetic (SSR-PCR, capillary gel electrophoresis with fluorescent detection of fragments) and statistical (descriptive statistics, cluster analysis, χ2) analysis methods was used. Plant material used were 33 samples of corn kernels including mutant forms with a high content of amylose, amylopectin, short-chain starches, were kindly provided by VIR genetic collection (Russian Federation) and Maize Genetics Cooperation Stock Center (USA). The contents of starch, short-chain soluble carbohydrates, amylose, amylopectin in the grain of 33 maize samples were evaluated. Compositionally similar (to endosperm carbohydrates content) groups of samples were identified. They include 13 high-amylopectin samples carriers of waxy (wx) gene mutations and 20 samples with wild-type character (Wx). Molecular genetic screening of the collection included an analysis of the polymorphism of the microsatellite loci phi022, phi027, phi061 associated with the waxy gene sequence. Allelic composition of individual loci and their combinations were analyzed in relation to the accumulation of reserve carbohydrates in the kernel endosperm. Only the analysis of the phi022/phi027 combination or all three markers in the complex allows differentiating the wild Wx and mutant wx phenotypes of maize. It was shown that not the individual allelic polymorphisms of the phi022, phi027, phi061 loci are efficient for the markerassociated selection of high-amylopectin maize, but their unique combinations

Marker-assisted identification of maize genotypes with improved protein quality

Currently, more than 70 % of maize is used for food and fodder; therefore, grain quality improvement can increase its nutritive and energy value. Deficiency of two essential amino acids (lysine and tryptophan) significantly reduces the nutritional quality of maize proteins. However, in comparison to conventional maize varieties, opaque2 (o2) mutants have greater contents of lysine and tryptophan in their endosperm proteins and their bioavailability is better. The aim of the study was identification of maize accessions with high-quality protein. A collection of maize accessions of various ecogeographical origins was studied by molecular methods. This approach was expected to improve maize breeding efficiency. We collected 54 maize genotypes differing in grain quality performance. Amplification with three specific markers to the opaque-2 gene (phi057, phi112 and umc1066) revealed homozygous recessive o2 genotypes, associated with improved nutritional quality of the protein. UREA-PAG electrophoresis of zein proteins was used for Quality Protein Maize (QPM) identification. In addition to the mutant o2 allele, QPM contains genetic modifiers that convert starchy endosperm of o2 mutant to the hard vitreous phenotype. The selected QPM accessions are of interest for maize breeding programs aimed at grain quality improvement. The use of the markers to o2 and modifier genes accelerates the development of QPM varieties and significantly reduces the labor and financial costs of their production

Direct observation of free excitons in luminescence spectra of xenon clusters

Luminescence of surface and free bulk excitons is detected in xenon for the first time for substrate-free rare-gas clusters. Xenon clusters were produced by the method of gas condensation in a supersonic jet emitted into vacuum. Optical study was accompanied by electron diffraction measurements to determine the structure of clusters.Comment: The more complete version of the paper is to be published in 'Low Temperature Physics' (2007

Complex analysis of flax seeds composition for breeding programs

Single plant selection using complex of seed quality traits requires development and optimization of the methods, which allow qualitative and quantitative analysis applying minimum quantity of seeds. The proposed evaluation scheme of seed composition enables optimal use of seed material for individual plant analysis: oil percentage (Rushkovsky’s extraction method), fatty acid composition (vaporliquid chromatography), protein and ash content (dynamic thermogravimetry), elemental composition (electron probe X-ray fluorescence method). Reproducibility of analytical methods used was assessed by the coefficient of variation, the reproducibility index (ARI) and the convergence of data on seasonal cultivation

Informative EST-SSR markers for genotyping and intraspecific differentiation of Brassica oleracea var. capitata L.

Brassica oleraceae var. capitata L. is characterized by a high level of intraspecific heterogeneity due to some biological features that cause difficulties for breeding creating genetically homogenous forms and maintaining their genetic purity. Microsatellites (SSR) are highly polymorphic markers of plant genomes and represent one of the most effective tools for assessing genetic polymorphism. Among microsatellites, EST-SSR are most interesting, because they are directly linked to the expressed sequences and for that reason are widely used for analysis of genetic diversity and population structure. In this work, we studied the effectiveness of the use of transferable EST-SSR markers for both analyzing white cabbage diversity and genotyping pure lines. As a result, 15 microsatellite loci were characterized for the information content, allelic frequencies and heterogeneity levels. The effective multiallelic markers (Bo20TR, BoDCTD4, BoPC34, BoPLD1, BoCalc, BoPC15) with high information content (PIC > 0.7) that could be successfully used for analysis of inter- and intravarietal polymorphism in B. oleracea var. capitata were identified. It has been shown that intervarietal polymorphism expressed as the allelic diversity of EST SSR loci greatly facilitates varietal identification and typing of individual plants for breeding purposes. Based on the SSR-evaluation and subsequent clustering, the genetic structure of the breeding collection was identified, which showed that most experimental forms, in spite of different origin, have a common ancestral genetic basis. The identified donors of rare alleles could potentially be a source of valuable genetic segregation for further B. oleracea breeding improvement