Superconductor-Ferromagnet Bi-Layers: a Comparison of s-Wave and d-Wave Order Parameters

We study superconductor-ferromagnet bi-layers, not only for s-wave but also for d-wave superconductors. We observe oscillations of the critical temperature when varying the thickness of the ferromagnetic layer for both s-wave and d-wave superconductors. However, for a rotated d-wave order parameter the critical temperature differs considerably from that for the unrotated case. In addition we calculate the density of states for different thicknesses of the ferromagnetic layer; the results reflect the oscillatory behaviour of the superconducting correlations.Comment: 11 pages, 5 figures, accepted for publication in J. Phys.: Condens. Matte

Triplet proximity effect in FSF trilayers

We study the critical temperature T_c of FSF trilayers (F is a ferromagnet, S is a singlet superconductor), where the triplet superconducting component is generated at noncollinear magnetizations of the F layers. An exact numerical method is employed to calculate T_c as a function of the trilayer parameters, in particular, mutual orientation of magnetizations. Analytically, we consider limiting cases. Our results determine conditions which are necessary for existence of recently investigated odd triplet superconductivity in SF multilayers.Comment: 5 pages, 4 EPS figures; the style file jetpl.cls is included. Version 2: minor corrections, added reference. Version 3: minor correction

Influence of randomly distributed magnetic nanoparticles on surface superconductivity in Nb films

We report on combined resistance and magnetic measurements in a hybrid structure (HS) of randomly distributed anisotropic CoPt magnetic nanoparticles (MN) embedded in a 160 nm Nb thick film. Our resistance measurements exhibited a sharp increase at the magnetically determined bulk upper-critical fields Hc2(T). Above these points the resistance curves are rounded, attaining the normal state value at much higher fields identified as the surface superconductivity fields Hc3(T). When plotted in reduced temperature units, the characteristic field lines Hc3(T) of the HS and of a pure Nb film, prepared at exactly the same conditions, coincide for H10 kOe they strongly segregate. Interestingly, the characteristic value H=10 kOe is equal to the saturation field of the MN. The behavior mentioned above is observed only for the case where the field is normal to the HS, while is absent when the field is parallel to the film. Our experimental results suggest that the observed enhancement of surface superconductivity field Hc3(T) is possibly due to the not uniform local reduction of the external magnetic field by the dipolar fields of the MN.Comment: to be published in Phys. Rev.

Critical temperature of superconducting bilayers: theory and experiment

A generalized model for the critical temperature Tc of superconducting bilayers is presented, which is valid with no restrictions to film thicknesses, Tc of the layers and interface resistivity. The model is verified experimentally on a series of Nb-Al and Ta-Al bilayers with Nb, Ta layer thicknesses of 100 nm and Al layer thicknesses ranging from 5 nm to 200 nm. Excellent agreement between theory and experiment was found for the energy gap and the Tc of bilayers. The results are important for designing practical superconducting devices.Comment: 3 pages, 2 figure

Novel base-pairing interactions at the tRNA wobble position crucial for accurate reading of the genetic code

Posttranscriptional modifications at the wobble position of transfer RNAs play a substantial role in deciphering the degenerate genetic code on the ribosome. The number and variety of modifications suggest different mechanisms of action during messenger RNA decoding, of which only a few were described so far. Here, on the basis of several 70S ribosome complex X-ray structures, we demonstrate how Escherichia coli tRNA Lys UUU with hypermodified 5-methylaminomethyl-2-thiouridine (mnm 5 s 2 U) at the wobble position discriminates between cognate codons AAA and AAG, and near-cognate stop codon UAA or isoleucine codon AUA, with which it forms pyrimidine-pyrimidine mismatches. We show that mnm 5 s 2 U forms an unusual pair with guanosine at the wobble position that expands general knowledge on the degeneracy of the genetic code and specifies a powerful role of tRNA modifications in translation. Our models consolidate the translational fidelity mechanism proposed previously where the steric complementarity and shape acceptance dominate the decoding mechanism

A glimpse on Staphylococcus aureus translation machinery and its control

© 2016, Pleiades Publishing, Inc.Staphylococcus aureus is a major opportunistic and versatile pathogen. Because the bacteria rapidly evolve multi-resistances towards antibiotics, there is an urgent need to find novel targets and alternative strategies to cure bacterial infections. Here, we provide a brief overview on the knowledge acquired on S. aureus ribosomes, which is one of the major antibiotic targets. We will show that subtle differences exist between the translation at the initiation step of Gram-negative and Gram-positive bacteria although their ribosomes display a remarkable degree of resemblance. In addition, we will illustrate using specific examples the diversity of mechanisms controlling translation initiation in S. aureus that contribute to shape the expression of the virulence factors in a temporal and dynamic manner

Layered ferromagnet-superconductor structures: the π\pi state and proximity effects

We investigate clean mutilayered structures of the SFS and SFSFS type, (where the S layer is intrinsically superconducting and the F layer is ferromagnetic) through numerical solution of the self-consistent Bogoliubov-de Gennes equations for these systems. We obtain results for the pair amplitude, the local density of states, and the local magnetic moment. We find that as a function of the thickness $d_F$ of the magnetic layers separating adjacent superconductors, the ground state energy varies periodically between two stable states. The first state is an ordinary "0-state", in which the order parameter has a phase difference of zero between consecutive S layers, and the second is a "$\pi$-state", where the sign alternates, corresponding to a phase difference of $\pi$ between adjacent S layers. This behavior can be understood from simple arguments. The density of states and the local magnetic moment reflect also this periodicity.Comment: 12 pages, 10 Figure

One-stage reconstruction of defects of pharynx, mouth and maxilla during treatment of patients with head and neck cancer

The prospective research presents the data from 2009 - 2010 about using reconstructive and plastic component during combined operations of squamous cell carcinoma of pharynx, mouth and maxilla. 66 patients were included into the research to evaluate the short-term results of treatment of the patients with head and neck cancer. All of them were operated with defects and single-stage reconstruction of the defects using different types of musculocutaneous flaps was made. All the patients are with l-IV stages of squamous cell carcinoma of floor of mouth, tongue, oropharynx, hypopharynx, maxilla or with tumor recurrence of floor of mouth, tongue, oropharynx, hypopharynx, maxilla after noneffective radiotherapy and chemoraditherapy. The design of the research is case/control. The short-term results of treatment of the patients with using of local flaps with magistral type of blood circulation, distant flaps with magistral type of blood circulation and free revascularized flaps were analysed. Post-operative complications are 16,7 %. Post-operative mortality is 1,5 %.В проспективном исследовании представлены данные за 2009-201 Огг., об использованиии реконструктивно­пластического компонента при комбинированных операциях по поводу плоскоклеточного рака глотки, полости рта, верхней челюсти. С целью оценки непосредственных результатов лечения больных раком головы и шеи при проведении операций со сквозными дефектами и одномоментной пластикой дефектов различными видами кожно-мышечных лоскутов в исследование включено 66 человек. Все больные с I-IV стадиями плоскоклеточного рака дна полости рта, языка, ротоглотки, гортаноглотки, верхней челюсти или с рецидивом рака дна полости рта, языка, ротоглотки, гортаноглотки, верхней челюсти после неэффективной лучевой или химиолучевой терапии. Дизайн исследования - случай-контроль. Проанализированы непосредственные результаты лечения больных с применением локальных лоскутов с магистральным типом кровообращения, дистанционных лоскутов с магистральным типом кровообращения, свободных реваскуляризированных лоскутов. Послеоперационные осложнения составили 16,7%. Послеоперационная смертность -1,5 %

The first experience of using different types of musculocutaneous flaps during treatment of patients with head and neck cancer

19 patients were included into the research to evaluate the short-term results of treatment of the patients with head and neck cancer. All of them were operated with defects and single-stage reconstruction of the defects using different types of musculocutaneous flaps was made. All the patients are with l-lll stages of squamous cell carcinoma of floor of mouth, tongue, oropharynx or with tumor recurrence of floor of mouth, tongue, oropharynx after noneffective radiotherapy and chemoraditherapy. The design of the research is case/control.The short-term results of treatment of the patients with using of local flaps with magistral type of blood circulation, distant flaps with magistral type of blood circulation and free revascularized flaps were analysed. Post-operative complications are 10,6 %. Post-operative mortality is 5,3 %.С целью оценки непосредственных результатов лечения больных раком головы и шеи при проведении операций со сквозными дефектами и одномоментной пластикой дефектов различными видами кожно-мышечных лоскутов в исследование включено 19 человек. Все больные с I-III стадиями плоскоклеточного рака дна полости рта, языка, ротоглотки, или с рецидивом рака дна полости рта, языка, ротоглотки после неэффективной лучевой или химиолучевой терапии. Дизайн исследования - случай-контроль. Проанализированы непосредственные результаты лечения больных с применением локальных лоскутов с магистральным типом кровообращения, дистанционных лоскутов с магистральным типом кровообращения, свободных реваскуляризированных лоскутов. Послеоперационные осложнения составили 10,6%. Послеоперационная смертность - 5,3 %