Nodal structure of quasi-2D superconductors probed by magnetic field

We consider a quasi two-dimensional superconductor with line nodes in an in-plane magnetic field, and compute the dependence of the specific heat, $C$, and the in-plane heat conductivity, $\kappa$, on the angle between the field and the nodal direction in the vortex state. We use a variation of the microscopic Brandt-Pesch-Tewordt method that accounts for the scattering of quasiparticles off vortices, and analyze the signature of the nodes in $C$ and $\kappa$. At low to moderate fields the specific heat anisotropy changes sign with increasing temperature. Comparison with measurements of $C$ and $\kappa$ in CeCoIn$_5$ resolves the contradiction between the two in favor of the $d_{x^2-y^2}$ gap.Comment: 5 pages, 3 figure

Interaction of vortices in superconductors with kappa close to 2^(-1/2)

Using a perturbative approach to the infinitely degenerate Bogomolnyi vortex state for a superconductor with kappa = 2^(-1/2), T -> T_c, we calculate the interaction of vortices in a superconductor with kappa close to 2^(-1/2). We find, numerically and analytically, that depending on the material the interaction potential between the vortices varies with decreasing kappa from purely repulsive (as in a type-II superconductor) to purely attractive (as in a type-I superconductor) in two different ways: either vortices form a bound state and the distance between them changes gradually from infinity to zero, or this transition occurs in a discontinuous way as a result of a competition between minima at infinity and zero. We study the discontinuous transition between the vortex and Meissner states caused by the non-monotonous vortex interaction and calculate the corresponding magnetization jump.Comment: v1:original submit v2:changed formate of images (gave problems to some) v3:corrected fig v4v6 (was -v4v6) orthographic corrections (and U_lat/int) mismatch v4:more small orthographic corrections v5:converted to revtex4 and bibTex v6:Renamed images to submit to pr

Identification of <i>Rca2</i> and <i>Rpf1</i> resistance alleles in strawberry breeding forms of intervarietal hybrid origin

Background. The creation of varieties with genetic resistance to fungal pathogens is one of the most important directions in strawberry breeding. A promising direction of accelerated selection of valuable specimens is molecular screening for the presence in their genotype of diagnostic DNA markers, linked to target genes of agrobiological traits. Objectives of the work were determination of the allelic state of the Rca2 (resistance to anthracnose) and Rpf1 (resistance to red stele root rot) genes in selected strawberry forms to identify genotypes resistant to Colletotrichum acutatum Simmonds and Phytophthora fragariae var. fragariae Hickman.Material and methods. The object of research was breeding forms of strawberries of intervarietal hybrid origin. As a result of 22 crossing combinations, 61 selection forms were obtained, in which the allelic composition of resistance genes was studied. The Rca2 anthracnose resistance allele was identified by means of the STS-Rca2_240 marker. The Rpf1 red stele root rot resistance allele was identified with the help of SCAR-R1A marker. Results. At least one of the two genes was identified in 20 selected strawberry forms (32.8%). The STS-Rca2_240 marker was identified in 15 strawberry seedlings (22.9%) from six hybrid combinations ‘Vicoda’ × ‘Roxana’, ‘Florence’ × ‘Faith’, ‘Asia’ × ‘Aprica’, ‘San Andreas’ × ‘Monterey’, ‘Alisa’ × ‘Quicky’, ‘Quicky’ × ‘Olympia’). The SCAR-R1A marker was identified in five strawberry seedlings (8.2%) from four hybrid combinations (‘Privlekatelnaya’ × ‘Bylinnaya’, ‘Feyerverk’ × ‘Bylinnaya’, ‘Bylinnaya’ × ‘Feyerverk’, ‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’). It has been established that all strawberry selected forms with identified marker fragments for resistance genes are characterized by a heterozygous combination of alleles.Conclusions. Promising sources of resistance alleles are strawberry selected forms: 2/1-24, 2/1-34 (‘Quicky’ × ‘Olympia’), 3/9-5 (‘Florence’ × ‘Faith’), 3/12-2, 3/12- 9 (‘Alisa’ × ‘Quicky’), 4/7-10, 4/7-19, 4/7-20 (‘Asia’ × ‘Aprica’), 5/2-26, 5/2-32 (‘San Andreas’ × ‘Monterey’), 9/ 1-11, 9/1-12, 9/1-13, 9/1-32, 9/1-37 ‘Vicoda’ × ‘Roxana’) in case of Rca2 gene; 72-24, 72-71 (Privlekatelnaya × Bylinnaya), 69-29 (‘Feyerverk’ × ‘Bylinnaya’), 62-41 (‘Bylinnaya’ × ‘Feyerverk’), 61-15 (‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’) in case of Rpf1 gene

Allelic diversity of the <i>FaOMT</i> gene (mesifurane biosynthesis) in promising strawberry cultivars and selected forms developed at the I.V. Michurin Federal Science Center

Background. Fruit aroma is an important consumer trait of strawberry varieties. Identification of genotypes carrying the genes of the aromatic complex in fruits is an important stage in the development of new cultivars with aromatic fruits. The purpose of this study was to analyze the allelic state of the FaOMT fruit aroma gene in strawberry cultivars and selected forms developed at the I.V. Michurin Federal Science Center to identify promising genotypes for use in breeding for fruit aroma.Materials and methods. The research materials were strawberry cultivars and promising selected forms developed at the I.V. Michurin FSC using the methods of introgressive and intervarietal hybridization. Allelic state of the FaOMT gene was identified with the codominant marker FaOMT-SI/NO.Results and conclusion. The FaOMT fruit aroma gene is represented in the studied strawberry varieties and forms by three combinations of alleles: the homozygous state of the functional allele, the heterozygous combination of the alleles, and the homozygous state of the nonfunctional allele. Cvs. ‘Rubinovy kaskad’, ‘Privlekatelnaya’ and ‘Feyerverk’ are characterized by a heterozygous combination of alleles of the FaOMT gene. Cvs. ‘Lastochka’, ‘Pamyati Zubova’, ‘Flora’, ‘Yarkaya’ and ‘Urozhaynaya CGL’ are characterized by the homozygous state of the FaOMT+ allele. Selected strawberry forms 928-12, 26-5, 72-71 and 62-41 have the heterozygous genotype; hybrids 298-19-9-43 and 932-29 are characterized by the homozygous state of the FaOMT+ allele; selected forms 61-12 and 65-26 are characterized by the homozygous state of the nonfunctional FaOMT– allele. Strawberry forms promising for breeding, with the homozygous state of the functional FaOMT+ allele, were identified: cvs. ‘Lastochka’, ‘Pamyati Zubova’, ‘Flora’, ‘Yarkaya’ and ‘Urozhaynaya CGL’, and selected forms 298-19-9-43 and 932-29

Genetic diversity in wild species and cultivars of strawberry for the FanAAMT gene controlling fruit flavor volatiles

Background. An important consumer trait of strawberry fruits is their aroma. Methyl anthranilate makes a considerable contribution to the fruit flavor. The methyl anthranilate content in strawberry fruits is controlled by the FanAAMT (аnthranilic acid methyltransferase) gene. Identification of genetic determinants for this trait facilitates targeted selection of promising forms based on diagnostic DNA markers. The purpose of this study was to study the allelic diversity of the FanAAMT fruit flavor gene in wild strawberry species and strawberry cultivars for identification of promising genotypes.Materials and methods. The objects of this study were wild species of Fragaria L. as well as F. × anaschata Kantor. and F. × ananassa Duch. cultivars of different ecogeographic origin. The FanAAMT gene was identified with the dominant marker FanAAMT.Results and conclusion. In the analyzed collection of strawberry genotypes, the FanAAMT gene was identified in 36.4% of the forms, including the wild species F. vesca L., F. moschata Duch. and F. virginiana subsp. platypetala (Rydb.) Staudt, and cv. ‘Kupchikha’ (F. × anaschata). Among the analyzed F. × ananassa cultivars, the FanAAMT gene was found in 31.6% of the tested forms, specifically in 27.3% of the 22 Russian cultivars, and 37.5% of the analyzed foreign ones. Promising sources of high methyl anthranilate content in fruits were identified: wild spp. F. moschata, F. vesca, and F. virginiana subsp. platypetala; cv. ‘Kupchikha’ (F. × anaschata); Russian garden strawberry cvs. ‘Bylinnaya’, ‘Zenit’, ‘Lastochka’, ‘Neznakomka’, ‘Feyerverk’ and ‘Tsarskoselskaya’; and foreign garden strawberry cvs. ‘Karmen’, ‘Ostara’, ‘Samson’, ‘Symphony’, ‘Troubadour’ and ‘Vima Tarda’, in which the functional allele of the FanAAMT gene was found. In the remaining studied strawberry genotypes the marker FanAAMT was not detected, which presumably indicates that the FanAAMT gene is absent. cells (R9.4.1)

Analysis of the inheritance of the marker SCAR-R1A, linked to the <i>Rpf1</i> red stele root rot resistance gene, in strawberry hybrid progeny

Background. Resistance to pathogens is an important breeding trait of a cultivar. Red stele root rot (Phytophthora fragariae var. fragariae Hickman) is a dangerous root disease. Revealing the patterns of resistance inheritance and identifying promising genotypes is an important stage in the development of strawberry cultivars resistant to red stele root rot. The purpose of the study was to identify patterns of inheritance for the SCAR-R1A marker, linked to the Rpf1 red stele root rot resistance gene, in the strawberry hybrid combinations.Materials and methods. The target materials were the strawberry cultivars ‘Bylinnaya’, ‘Olimpiyskaya Nadezhda’, ‘Privlekatelnaya’ and ‘Feyyerverk’, and hybrid seedlings of the cross combinations Bylinnaya × Olimpiyskaya Nadezhda, Bylinnaya × Feyyerverk, Olimpiyskaya Nadezhda × Bylinnaya, Privlekatelnaya × Bylinnaya, and Feyyerverk × Bylinnaya. The Rpf1 gene was identified with the marker SCAR-R1A.Results and conclusion. For the hybrid combination Bylinnaya × Olimpiyskaya Nadezhda, the percentage of seedlings with an Rpf1 resistance allele was 33.3%. For the combination Bylinnaya × Feyyerverk, their percentage was 37.2%; for Olimpiyskaya Nadezhda × Bylinnaya, 39.4%; for Privlekatelnaya × Bylinnaya, 39.6%; and for Feyyerverk × Bylinnaya, 36.2%. The average percentage of seedlings with an Rpf1 allele for the studied combinations was 37.1%. Assessment of the compliance between the observed segregation and theoretical one according to the χ2  criterion confirmed the monogenic character of the studied trait and the Mendelian ratio of inheritance frequencies for the marker fragments of the Rpf1 gene as 1 : 1. Therefore, all identified seedlings with an Rpf1 allele are characterized by a heterozygous genotype. Strawberry hybrids promising for breeding were identified: 62-41 (Bylinnaya × Feyyerverk), 65-17, 65-24 (Olimpiyskaya Nadezhda × Bylinnaya), and 69-29 (Feyyerverk × Bylinnaya)

Domain wall saddle point morphology in ferroelectric triglycine sulfate

Ferroelectric domain walls, across which there is a divergence in polarization, usually have enhanced electrical conductivity relative to bulk. However, in lead germanate, head-to-head and tail-to-tail walls are electrically insulating. Recent studies have shown that this is because, when oppositely oriented domains meet, polar divergence is obviated by a combination of domain bifurcation and suspected local dipolar rotation. To explore the uniqueness, or otherwise, of this microstructure, we have used tomographic piezoresponse force microscopy to map three-dimensional domain morphologies in another uniaxial ferroelectric system: triglycine sulfate. This mapping reveals an abundance of domain wall saddle points, which are characteristic of interlocking bifurcated domains. Conducting atomic force microscopy, performed close to the saddle points, showed no evidence for highly localized conducting domain wall sections, across which a divergence in polarization might be implied; this supports the notion that localized dipolar rotation occurs to minimize any potential polar discontinuity. Overall, our study, therefore, confirms that mutual domain bifurcation and suspected local dipolar rotation are not unique to lead germanate and instead may be widely present in other uniaxial ferroelectrics

Analysis of strawberry genetic collection (Fragaria L.) for Rca2 and Rpfl genes with molecular markers

Strawberry (Fragaria x ananassa Duch.) varieties are susceptible to many fungal diseases. Identification of forms, carrying resistance genes, is an important stage in breeding programs leading to resistant varieties. The use of molecular markers allows to determine with high reliability the presence of the necessary genes in the genome and to identify promising forms. Some of the common strawberry's diseases, causing significant damage to strawberry plantations, are anthracnose (Colletotrichum acutatum Simmonds) and red stele root rot (Phytophthora fragariae var. fragariae Hickman). Dominant Rca2 gene is involved in monogenic resistance to C. acutatum pathogenicity group 2. Rpf1, Rpf2, Rpf3 genes are determined in monogenic resistance to red stele root rot. The purpose of this study was molecular genetic testing genotypes of genus Fragaria L. to identify carriers of Rca2 allele anthracnose resistance and Rpf1 allele red stele root rot resistance. The objects of study were the wild species of the genus Fragaria L. and strawberry varieties (Fragaria x ananassa Duch.) of different ecological and geographic origin. To assess allelic state Rca2 anthracnose resistance gene the dominant SCAR marker STS-Rca2_240 was used, was linked to the resistance gene Rca2 with a genetic distance of 2.8 cM. Rpf1 gene red stele root rot resistance was identified with the dominant SCAR marker R1A, was linked to the resistance gene Rpf1 with a genetic distance of 3.0 cM. The resistant allele of the marker STS-Rca2_240 was identified in the Laetitia variety (Rca2Rca2 or Rca2rca2 genotype), which allows us to recommend it as a promising source in breeding for anthracnose resistance. The other studied forms have homozygous recessive state of the marker STS-Rca2_240 (putative genotype rca2rca2). The resistant allele of the marker SCAR-R1A in the varieties and wild species of strawberry under study is absent, which presumably indicates their homozygous recessive genotype of Rpf1 gene (rpf1rpf1)

Antiferromagnetic superconductors with effective mass anisotropy in magnetic fields

We derive critical field H_c2 equations for antiferromagnetic \textit{s}-wave, d_{x^2-y^2}-wave, and d_{xy}-wave superconductors with effective mass anisotropy in three dimensions, where we take into account (i) the Jaccarino-Peter mechanism of magnetic-field-induced superconductivity (FISC) at high fields, (ii) an extended Jaccarino-Peter mechanism that reduces the Pauli paramagnetic pair-breaking effect at low fields where superconductivity and an antiferromagnetic long-range order with a canted spin structure coexist, and (iii) the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO or LOFF) state. As an example, experimental phase diagrams observed in organic superconductor kappa-(BETS)_2FeBr_4 are theoretically reproduced. In particular, the upper critical field of low-field superconductivity is well reproduced without any additional fitting parameter other than those determined from the critical field curves of the FISC at high fields. Therefore, the extended Jaccarino-Peter mechanism seems to occur actually in the present compound. It is predicted that the FFLO state does not occur in the FISC at high fields in contrast to the compound lambda-(BETS)_2FeCl_4, but it may occur in low-field superconductivity for s-wave and d_{x^2-y^2}-wave pairings. We also briefly discuss a possibility of compounds that exhibit unconventional behaviors of upper critical fields.Comment: 11 pages, 9 figures, revtex

Phase Transition between the Cholesteric and Twist Grain Boundary C Phases

The upper critical temperature Tc2 for the phase transition between the Cholesteric phase (N*) and the Twist Grain Boundary C phase with the layer inclination tilted to the pitch axis (TGBct) in thermotropic liquid crystals is determined by the mean field Chen-Lubensky approach. We show that the N*-TGBct phase transition is split in two with the appearance of either the TGBA or the TGB2q phase in a narrow temperature interval below Tc2. The latter phase is novel in being superposed from two degenerate TGBct phases with different (left and right) layers inclinations to the pitch axis.Comment: Phys. Rev. E, to be publ; 24 pages, RevTeX + 3 ps figure