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Search Results: 1 - 10 of 586250 matches for " N. A. Stelmashenko "
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Disorder induced collapse of the electron phonon coupling in MgB$_{2}$ observed by Raman Spectroscopy
K. A. Yates,G. Burnell,N. A. Stelmashenko,D. -J. Kang,H. N. Lee,B. Oh,M. G. Blamire
Physics , 2003, DOI: 10.1103/PhysRevB.68.220512
Abstract: The Raman spectrum of the superconductor MgB$_{2}$ has been measured as a function of the Tc of the film. A striking correlation is observed between the $T_{c}$ onset and the frequency of the $E_{2g}$ mode. Analysis of the data with the McMillan formula provides clear experimental evidence for the collapse of the electron phonon coupling at the temperature predicted for the convergence of two superconducting gaps into one observable gap. This gives indirect evidence of the convergence of the two gaps and direct evidence of a transition to an isotropic state at 19 K. The value of the electron phonon coupling constant is found to be 1.22 for films with T$_{c}$ 39K and 0.80 for films with T$_{c}\leq$19K.
A new kind of vortex pinning in superconductor / ferromagnet nanocomposites
A. Palau,H. Parvaneh,N. A. Stelmashenko,H. Wang J. L. Macmanus-Driscoll,M. G. Blamire
Physics , 2006, DOI: 10.1088/0953-2048/20/9/S04
Abstract: This paper reports the observation of hysteresis in the vortex pinning in a superconductor / ferromagnetic epitaxial nanocomposite consisting of fcc Gd particles incorporated in a Nb matrix. We show that this hysteretic pinning is associated with magnetic reversal losses in the Gd particles and is fundamentally different in origin to pinning interactions previously observed for ferromagnetic particles or other microstructural features.
Growth of Strongly Biaxially Aligned MgB2 Thin Films on Sapphire by Post-annealing of Amorphous Precursors
A. Berenov,Z. Lockman,X. Qi,Y. Bugoslavsky,L. F. Cohen,M. -H. Jo,N. A. Stelmashenko,V. N. Tsaneva,M. Kambara,N. Hari Babu,D. A. Cardwell,M. G. Blamire,J. L. MacManus-Driscoll
Physics , 2001, DOI: 10.1063/1.1424070
Abstract: MgB2 thin films were cold-grown on sapphire substrates by pulsed laser deposition (PLD), followed by post-annealing in mixed, reducing gas, Mg-rich, Zr gettered, environments. The films had Tcs in the range 29 K to 34 K, Jcs (20K, H=0) in the range 30 kA/cm2 to 300 kA/cm2, and irreversibility fields at 20 K of 4 T to 6.2 T. An inverse correlation was found between Tc and irreversibility field. The films had grain sizes of 0.1-1 micron and a strong biaxial alignment was observed in the 950C annealed film.
Superconductor-ferromagnet nanocomposites created by co-deposition of niobium and dysprosium
Rafael B. Dinner,Suman-Lata Sahonta,Rong Yu,Nadia A. Stelmashenko,Judith L. MacManus-Driscoll,Mark G. Blamire
Physics , 2009, DOI: 10.1088/0953-2048/22/7/075001
Abstract: We have created superconductor-ferromagnet composite films in order to test the enhancement of critical current density, Jc, due to magnetic pinning. We co-sputter the type-II superconductor niobium (Nb) and the low-temperature ferromagnet dysprosium (Dy) onto a heated substrate; the immiscibility of the two materials leads to a phase-separated composite of magnetic regions within a superconducting matrix. Over a range of compositions and substrate temperatures, we achieve phase separation on scales from 5 nm to 1 micron. The composite films exhibit simultaneous superconductivity and ferromagnetism. Transport measurements show that while the self-field Jc is reduced in the composites, the in-field Jc is greatly enhanced up to the 3 T saturation field of Dy. In one instance, the phase separation orders into stripes, leading to in-plane anisotropy in Jc.
Dynamic Changes in Lipid Peroxidation and Antioxidant Level in Rat’s Tissues with Macrovipera lebetina obtusa and Montivipera raddei Venom Intoxication  [PDF]
N. A. Zaqaryan, N. A. Ghazaryan, N. M. Ayvazyan
Journal of Biophysical Chemistry (JBPC) , 2014, DOI: 10.4236/jbpc.2014.54017
Abstract: We investigated the balance of free radicals in different tissues (liver, heart, brain and muscle) of rats in course of in vivo and in vitro processing by Macrovipera lebetina obtusa (MLO) and Montivipera raddei (MR) snake venoms. Chemiluminescence (ChL) levels were examined in tissue assays after incubation (at 37 °C for a period of 10 min) with venom for in vitro experiments and in tissue assays isolated of 10 min after venom injection for in vivo experiments. The TBA-test was also performed to confirm the free radical expression. The activities of antioxidant enzymes (such as superoxide dismutase and glutathione peroxidase) in isolated tissues were detected by spectro-photometry. During the in vitro processing chemiluminescence levels of tissue homogenates significantly decreased, while in course of in vivo intoxication the level of ChL was elevated in brain and liver; lipid peroxidation also increased in brain tissue, but there was no significant balance change in other tissues; the activity of superoxide dismutase mainly correlated with changes of free radical balance during intoxication. On the contrary, the activity of glutathione peroxidase showed the reverse tendencies to change. We suggest that free radicals and their oxidative stresses may play a role in the early stage of intoxication causing the so-named “spreading-effect”, which is very characteristic for the venom of vipers.
Review of the Book “Causality and Reversibility in Irreversible Time”  [PDF]
A. N. Morozov
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.33029
Abstract: The book concerns a number of the most fundamental concepts and problems of modern physics: causality, entanglement and the nature of time. A distinguishing feature of author’s approach is equal attention to both the theoretical and experimental challenges posed by those issues. From very beginning, in Introduction the author points out Kozyrev causal mechanics, suggested about fifty years ago, as an inspirable source of ideas devel-oped him at the modern level of rigor.
Evolving Green Aviation Transport System: A Hoilistic Approah to Sustainable Green Market Development  [PDF]
A. N. Sarkar
American Journal of Climate Change (AJCC) , 2012, DOI: 10.4236/ajcc.2012.13014
Abstract: Aviation is one of the fastest growing industries as well as transportation modes in the world. Global aviation contributes about 2% of global greenhouse gas emissions and supports 8% of the world economic activity in terms of GDP. With the phenomenal growth in air trafficking by the national and international airliners the total carbon space available for flying is getting progressively diminished and the consequential emission levels are also becoming alarming over passage of time. The paper describes the concept of evolution of Green Transport system with focus on manufacturing of green aircraft and sustainable green marketing involving green supply chain. This entails introduction of New and innovative technologies, including aircraft designing, improving operational efficiency, air traffic control & monitoring etc; combined with emission mitigation efforts towards sustainable growth of the industry, can make enormous improvements in emission control and reduction in a planned and system-based manner. These integrated approaches are proposed to be used to harmonize the systems and processes that can essentially constitute the suggested framework of the Green Aviation Transport system. The paper, inter alia, discusses various conceptual, strategic, technological and economic and environmental dimensions of the Green Aviation transport system with focus on creating new Green Marketing opportunities for the aviation industry in future.
Theory of pleiotropic action of biologically active compounds and medicines—Basic principles and practical application  [PDF]
N. A. Bizunok
Open Journal of Clinical Diagnostics (OJCD) , 2013, DOI: 10.4236/ojcd.2013.33017
Abstract: This article represents the main positions of the theory of pleiotropic action of biologically active compounds (BACs) and medicines, which has been designed by the author based on her own experimental researches. The term “pleiotropy” means the ability of the BACs and medicines to implement more than one mechanism of action resulting in the specific biological (pharmacological) effect. The interaction of these mechanisms forms a distinct pattern of biological response (pleiotropic pattern), which reflects the change in his character with the increased dose (concentration)-dependent efficacy of BACs and medicines. The article consists of description of different pleiotropic patterns established in experiments on the model of reactive oxygen species (ROS) generation by macrophages dependent on activity of specialized enzyme called Nox2-NAD(P)H oxidase (Nox2, EC 1.6.3.1). Moreover, it consists of explanation of pharmacodynamic nature of pleiotropic patterns by means of application Chou-Talalay median effect equalization and combination index (CI) theory. The novel theory explains unsolved until now universal aspects of activity BACs and medicines, such as slope angles of “dose-effect” dependences in the conditions relevant in vivo, and it is of fundamental interest. However, it has applications in experimental pharmacology, as it allows defining the choice of the individual compounds and combinations, modulating the trust effect selectively and efficiently. This knowledge opens up new approaches to medicines discovery and evaluation, their rational dosing and combining.
Optimal Placement of Distributed Generation for Reliability Benefit in Distribution Systems  [PDF]
N. Rugthaicharoencheep, A. Chalangsut
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B132
Abstract:

A distributed generator is a small-scaled active

Planktonic Foraminifera Diversity in the Sea of Okhotsk and Correlation to Past Climate Change  [PDF]
A. Romanova, N. Iurchenko
Journal of Geoscience and Environment Protection (GEP) , 2014, DOI: 10.4236/gep.2014.23011
Abstract:

80 sediment stations and 4 sediment cores collected in the Sea of Okhotsk were used in this study in order to reveal additional proxy for past climate reconstruction based on planktonic foraminifera. Variation in diversity indices (Simpson, Shannon and equitability indices) along the sea became additional criteria for 5 biogeographical provinces based on planktonic foraminifera. All of them show different structure aspects of the planktonic foraminifera assemblages that is very informative in cases of high relative abundance of N. pachyderma sin. and influence of carbonate dissolution factor. During the last 100 ky the diversity indices were changed and we can assume the migration of biogeographical provinces borders: borders of the Northern province were mov- ed to the central part in cold MIS 2, 4, structure of assemblages during MIS 3, 5 was close to the modern Central province but characterized by low total foraminiferal abundance in the sediments. The Simpson and Shannon indices are more sensitive to changes in structure of planktonic foraminifera assemblages when equitability index varies lightly during the Late Pleistocene-Holocene.

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