889 research outputs found
On the Equivalence of Dual Theories
We discuss the equivalence of two dual scalar field theories in 2 dimensions.
The models are derived though the elimination of different fields in the same
Freedman--Townsend model. It is shown that tree -matrices of these models do
not coincide. The 2-loop counterterms are calculated. It turns out that while
one of these models is single-charged, the other theory is multi-charged. Thus
the dual models considered are non-equivalent on classical and quantum levels.
It indicates the possibility of the anomaly leading to non-equivalence of dual
models.Comment: 14 pages, LaTeX; 2 figures, encapsulated PostScrip
Investigation of the influence of technological conditions of microarc oxidation of magnesium alloys on their structural state and mechanical properties
Наведені дослідження структури і властивостей покриттів, отриманих при мікродуговій обробці на магнієвому сплаві. Обробка проводилася при анодно-катодному режимі в лужному електроліті з різними домішками. Показана можливість формування кристалічних оксидних покриттів різного фазового складу (MgO, MgAl₂O₄, Mg₂Sі₄, Mg₃(PO₄)₂) товщиною до 300 мкм, що мають високу адгезію з основою, гарні захисні властивості і високу твердість, яка досягає 6,6 ГПа
The methodological problems of “human-sizedness” of modern cosmological theories
The article is picking up new methodological approaches to the study of the Cosmos and the understanding of the place of a human being in the Universe. The article has a methodological character and is presented in the form of the analysis and synthesis of various aspects of the study of this problem. The article considers theoretical and methodological aspects of cosmology, the analysis of modern scientific theories, the scope of their applicability. The obtained outputs can be used in cosmological modeling and in the studies of anthropological and existential aspects of cosmologyyesБелгородский госуниверсите
Influence of the thermal factor on the composition of electron-beam high-entropy ALTiVCrNbMo coatings
This paper reports results of studying the element and phase compositions of electron-beam coatings based on the high-entropy alloy AlTiVCrNbMo, depending on the deposition temperature (in the range of 300...700 °С).
The high-entropy alloys were melted in an arc furnace in an atmosphere of high-purity argon. Vacuum condensates of the high-entropy alloy (AlTiVCrNbMo) with a thickness of 3–5 µm were obtained in the vacuum setup UVN-2M-1 at a working vacuum of 5·10-5 mТоrr. The alloy evaporation was performed from the water-cooled ingot mold using an electron-beam gun with a power of 5 kW. Condensation of vapors of all the elements of the alloy was performed onto copper substrates at temperatures of 300, 500, 700 °C. Based on analysis of the element composition of materials of the target made of the high-entropy six-element alloy AlTiVCrNbMo and electron-beam coatings, based on it, we established the critical parameter (specific heat of vaporization of an element) that defined a selective change in the element composition. In accordance with a characteristic change in the composition of coatings of the multi-element high-entropy alloy, 3 groups of elements were distinguished: with a specific heat of evaporation of 280...350 kJ/mol (group 1), 420…460 kJ/mol (group 2), and 590…680 kJ/mol (group 3). It was shown that the formation of a single-phase coating of the high-entropy alloy (based on BCC of the crystalline lattice) occurs at the higher deposition temperature of 500...700 °C when the coating consists of not less than 5 elements. It was established that based on the conditions for an electron-beam process of materials formation, the results obtained can be divided into two types: those determined by the condition of evaporation of the target and those determined by the conditions of coating deposition. The density of flows of elements, evaporated from the target, is determined by their specific heat of evaporation. However, the ratio of atoms in the flow, derived in this way, may not be retained in the formed coating due to the secondary evaporation of elements from the growth surface. The obtained results allow us to substantiate principles for the selection of components for achieving the optimal element and phase compositions of high-entropy alloys.На основі аналізу елементного складу матеріалів мішені з високоентропійного шестиелементного сплаву AlTiVCrNbMo і електронно-променевих покриттів на його основі встановлено критичний параметр (питома теплота випаровування елемента), який визначає селективну зміну елементного складу. Показано, що формування однофазного покриття високоентропійного сплаву відбувається, коли до складу покриття входить не менше 5 елементів. Отримані результати дозволяють обґрунтувати принципи підбору компонент для досягнення оптимальних елементного та фазового складу високоентропійних сплавів
Forecasting System Requirements to the Materials of the Shell of Fuel Elements of Innovative Fast Reactors
Innovative nuclear energy system (INSS) designed to ensure effective use of uranium 238 and thorium 232 to produce energy. Maintain the neutron balance of this process requires the development and use of new types of nuclear fuel and structural materials. This requires the development of models to predict changes in theirproperties under the action of fields of different radiation, temperature, stress and exposure to various chemical substances. It is important achievement is not the limiting parameters, and the optimal combination of the properties of materials and their working conditions. In this paper parameters such as the fluence of fast neutrons, the reaction rate in the fuel rod cladding and the change of nuclide composition, in particular, developments of hydrogen and helium, influencing the change of the strength properties of steels, are calculated
Isolation, phenotype, and allostimulatory activity of mouse liver dendritic cells
Donor liver-derived dendritic cells (DC) have recently been identified within various lymphoid and nonlymphoid tissues of organ allograft recipients, including nonimmunosuppressed mice transplanted with and permanently accepting major histocompatibility complex (MHC)-disparate hepatic allografts. These findings have raised questions about the basis of the tolerogenicity of the liver—and, in particular, about the properties of liver-derived DC. To study further the structure, immunophenotype and allostimu-latory activity of leukocytes resident in normal mouse (B10.BR; H-2k, I-Ek) liver, a procedure was developed to maximize the yield of viable, nonparenchymal cells (NPC) obtained following collagenase digestion of perfused liver fragments and density centrifugation (Per-coll). These cells comprised populations expressing lymphoid and myeloid cell surface antigens. As compared with spleen cells, they proved good allostimula-tors of naive (BIO; H-2b, I-E") splenic T cells when tested in primary mixed leukocyte reactions (MLR). After overnight (18-hr) incubation of the NPC, enrichment for transiently adherent, low-density (LD) cells on metrizamide gradients permitted the recovery of low numbers of cells (approx. 2-5 × 105 per liver), many of which displayed distinct DC morphology. Flow cytometric analysis revealed that these cells were CD3-, CD4-, CD8-, and B220-, but strongly expressed CD45 (leukocyte-common antigen), and mild-to-moderate levels of CD lib, heat-stable antigen, and CD44. The cells also expressed moderate intensity of NLDC 145 but not 33D1, DC restricted markers which have been shown to be differentially expressed on mouse DC isolated from various organs. This DC-enriched population was more strongly MHC class II(I-Ek)+ than NPC, as determined by immunocytochemistry and flow cytometry and exhibited much more potent allo-stimulatory activity for naive T cells. These findings demonstrate that freshly isolated murine liver NPC, and perhaps their counterparts in situ, exhibit allo-stimulatory activity that is enhanced in the nonadherent, low-density (DC-enriched) fraction after overnight culture. They further suggest that the © 1994 by Williams and Wilkins
Transplant arteriosclerosis: an enigmatic disease due to a misnomer
Solid organ transplantation across the allogeneic barrier, pioneered by
Thomas Starzl, has by now become a common medical procedure. Unfortunately, the
number of donor organs lost due to transplant arteriosclerosis (chronic
rejection), remains significant and unchanged for decades. We argue that
designation of transplant arteriosclerosis as chronic rejection, and its
classification as a delayed long-lasting reaction of recipient immune effectors
against donor alloantigens have given us a wrong impression that we have
identified the necessary cause/pathogenesis of the tissue pathology. However,
whatever treatment options we have in the anti-rejection toolbox, despite their
success in treating classical rejection, do not work for the transplant
arteriosclerosis. Yet, the scientific community has continued to conceptualize
and approach the pathology within the alloimmunity model. Due to unproductive
research from the alloimmunity and rejection perspective, the number of
transplanted hearts lost due to this pathology today is almost the same as it
was fifty years ago. We believe that this phenomenon falls under the rubric of
linguistic relativity, and that language we chose to name the disease has
restricted our cognitive ability to solve the problem. While the initial
perception of the transplant arteriosclerosis as chronic rejection was logical
and scientific, the subsequent experience revealed that such perception and
approach have been fruitless, and likely are incorrect. Considering our tragic
failure to prevent and treat the delayed arterial pathology of donor organs
using all available knowledge on alloimmunity and rejection, we must finally
disassociate the former from the latter. The only way to start this
uncomfortable process is to change the words we are using; particularly, the
words we chose to name the disease. We have to step out of the alloimmunity
rejection box.Comment: 19 pages, 2 figure
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