Plasticity of an extra-strong nanocrystalline stainless steel controlled by the "dislocation-segregation'' interaction

We study three structurally different states of nanocrystalline 316 steel and show that the state, where boundaries containing excess concentration of alloying elements are combined with mobile dislocations in grain interiors, allows maintaining extraordinarily high strength and remarkably enhanced plasticity. Underlying mechanisms featuring interaction between the segregations and mobile dislocations are discussed

Efficiency of SSR and PawS markers for evaluation of genetic polymorphism among red clover (Trifolium pratense L.) cultivars

Background. Identification of crop varieties is presently one of the most important aspects due a significant annual increase in the number of newly developed cultivars. Application of molecular markers makes it possible to identify cultivars and secure protection of plant breeders’ rights. Marker techniques based on SSR loci and PawS markers were evaluated for their efficiency in revealing the DNA polymorphism in Russian red clover cultivars, and the research results are presented in this publication.Materials and Methods. The total genome DNA was extracted by a modified SDS method from 30 seedlings per each cultivar. Nine simple sequence repeats (SSR) and 4 PawS markers were used for genotyping. The basic genetic diversity parameters were measured and analyzed using the software resources GelAnalyzer 2010а, MStools v.3, and Statistica 7.0.Results and conclusion. The mean level of intervarietal DNA polymorphism in red clover was 38.6%. Cultivar-specific amplicons were obtained for 4 accessions (cvs. ‘Trifon’, ‘Topaz’, ‘Trio’ and ‘Mars’) with SSR loci RCS1307 and RCS3095. These loci were found appropriate for identification and certification of such cultivars. The tested PawS markers (individually and in combinations) proved non-informative for the analysis of intervarietal DNA polymorphism in red clover. The only primer pair PawS5+PawS16 generated reproducible PCR products, but unique amplicons were absent in the DNA profiles. The data obtained in this study may be helpful for further identification and certification of Russian red clover cultivars and promising breeding materials

Investigation of genetic polymorphism of Russian rape and turnip rape varieties using SSR and SRAP markers

Rapeseed (Brassica napus L.) and turnip rape (B. rapa L. subsp. campestris (L.)) are important agricultural plants widely used for food, fodder and technical purposes and as green manure. Over the past decades, a large number of perspective varieties that are being currently cultivated in every region of Russia have been developed. To increase the breeding efficiency and facilitate the seed production, modern molecular-genetic techniques should be introduced as means to estimate species and varietal diversity. The objective of the presented research study was to investigate DNA polymorphism of the rapeseed and turnip rape varieties developed at Federal Williams Research Center of Forage Production and Agroecology and detect informative markers for varietal identification and genetic certification. To genotype 18 gDNA samples, 42 and 25 combinations of respective SSR and SRAP primers were used. The results obtained demonstrate that SRAP markers were more effective for polymorphism analysis: 36 % of the tested markers revealed genetic polymorphism compared with only 16.7 % of microsatellite loci. Molecular markers to detect differences at interspecific and intervarietal levels have also been found. For the investigated set, such microsatellite loci as Na12A02, Ni2C12, Ni02-D08a, Ra02-E01, Ni03H07а and SRAP-marker combinations as F13-R9, Me4-R7, F11-Em2, F10-R7, F9-Em2 and F9-R8 proved to be informative. Application of the two marker techniques made it possible to detect a higher level of DNA polymorphism in plants of different types (spring and winter varieties) if compared against the intervarietal differences within a species or a group. According to Nei’s genetic diversity index, in the cluster of winter rapeseed, VIK 2 and Gorizont varieties had the longest genetic distance, and in the spring cluster, these were Novosel and Veles. A high level of similarity was found between Vikros and Bizon winter rapeseed varieties. The results obtained have a high practical value for varietal specification of seed material and genetic certification of rapeseed and turnip rape varieties

Topological String Amplitudes, Complete Intersection Calabi-Yau Spaces and Threshold Corrections

We present the most complete list of mirror pairs of Calabi-Yau complete intersections in toric ambient varieties and develop the methods to solve the topological string and to calculate higher genus amplitudes on these compact Calabi-Yau spaces. These symplectic invariants are used to remove redundancies in examples. The construction of the B-model propagators leads to compatibility conditions, which constrain multi-parameter mirror maps. For K3 fibered Calabi-Yau spaces without reducible fibers we find closed formulas for all genus contributions in the fiber direction from the geometry of the fibration. If the heterotic dual to this geometry is known, the higher genus invariants can be identified with the degeneracies of BPS states contributing to gravitational threshold corrections and all genus checks on string duality in the perturbative regime are accomplished. We find, however, that the BPS degeneracies do not uniquely fix the non-perturbative completion of the heterotic string. For these geometries we can write the topological partition function in terms of the Donaldson-Thomas invariants and we perform a non-trivial check of S-duality in topological strings. We further investigate transitions via collapsing D5 del Pezzo surfaces and the occurrence of free Z2 quotients that lead to a new class of heterotic duals.Comment: 117 pages, 1 Postscript figur

\u3cem\u3eRPGRIP1\u3c/em\u3e and Cone-Rod Dystrophy in Dogs

Cone–rod dystrophies (crd) represent a group of progressive inherited blinding diseases characterized by primary dysfunction and loss of cone photoreceptors accompanying or preceding rod death. Recessive crd type 1 was described in dogs associated with an RPGRIP1 exon 2 mutation, but with lack of complete concordance between genotype and phenotype. This review highlights role of the RPGRIP1, a component of complex protein networks, and its function in the primary cilium, and discusses the potential mechanisms of genotype–phenotype discordance observed in dogs with the RPGRIP1 mutation

Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms.

Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings

Genetic structure of the collection of ryegrass (<i>Lolium</i>) cultivars: a study based on SSR and SCoT markers

Background. Current molecular and genetic approaches make it possible to accelerate ryegrass breeding, simplify source material evaluation, and increase its accuracy. The efficiency of PCR-based SSR and SCoT marker techniques was studied in the context of evaluating the genetic structure of annual and perennial ryegrass accessions and defining DNA-identifying markers.Materials and methods. Genomic DNA was isolated from the aggregate sample of 30 seedlings from each of the 15 analyzed cultivars according to the modified SDS DNA extraction protocol. In total, 20 SSR and 22 SCoT markers were used to assess genetic polymorphism. Basic parameters of the markers’ informative efficiency were identified. Genetic relationships among the studied cultivars were analyzed on the basis of the Neighbor-Joining dendrogram and Bayesian model.Results. To assess the genetic polymorphism of ryegrass species and varieties, 7 SSR loci were selected, for which 110 allelic variants were identified (34 alleles were unique for individual cultivars), and 9 SCoT loci, for which 78 polymorphic amplification fragments were identified, with 28 being cultivar-specific. The dendrogram of genetic similarity and modeling in the Structure v2.3.4 program according to the results of SSR and SCoT analyses distributed the cultivars by their traits according to their species, ploidy level, origin, and similarity. Based on PCoA, carried out using summarized data of SSR and SCoT analyses, a multidimensional diagram of genetic relationships among ryegrass cultivars was constructed.Conclusions. The systems of SSR and SCoT markers appeared to be an efficient tool to reveal genetic polymorphism and identify differences among ryegrass species and cultivars. We found unique DNA profiles that can be used for genetic identification. The results of the study have practical significance in cultivar-specific identification and selection of cultivars for various purposes

Effect of Deformation-Induced Plasticity in Low-Alloyed Al-Mg-Zr Alloy Processed by High-Pressure Torsion

The influence of additional deformation heat treatments (DHTs), implemented by two regimes: (1) annealing and small additional deformation by high-pressure torsion (HPT) at room temperature (RT) and (2) HPT at elevated temperature to 10 turns and small additional HPT at RT, has been studied on the microstructure, mechanical properties and electrical conductivity of ultrafine-grained (UFG) Al-0.53Mg-0.27Zr (wt.%) alloy structured by HPT to 10 turns at RT. As is shown, both types of additional DHT lead to a substantial increase in plasticity (2–5 times) while maintaining high electrical conductivity (~53% IACS) and strength comprising 75–85% of the value in the pre-DHT state of the UFG alloy. The possible physical reasons for the revealed changes in the physical and mechanical properties are analyzed. Comparison of the strength and plasticity changes with the microstructure evolution after DHT of both types indicates that the increase in the density of introduced grain boundary dislocations is the most probable factor providing a tremendous increase in plasticity while maintaining a high level of strength in the UFG alloy under study. An outstanding combination of high strength (370 MPa), high elongation to failure (~15%) and significant electrical conductivity (~53% IACS) was achieved for the Al-Mg-Zr alloy. This combination of properties exceeds those obtained to date for this system, as well as for a number of other commercial conductor alloys based on the Al-Zr system