534 research outputs found
Study of diffusion properties of bidisperse magnetic fluids
Основной целью настоящего исследования является теоретическое изучение диффузии (потока частиц, цепочек из феррочастиц) в бидисперсных магнитных жидкостях с цепочечными агрегатами. Для этого сначала будет проведено исследование диффузионных свойств монодисперсной феррожидкости, которое в дальнейшем будет расширено на бидисперсные модели. В результате будет исследована зависимость диффузионных свойств системы от полидисперсности этой системы. Для бидисперсных систем будет исследовано влияние гранулометрического состава на поведение коэффициента диффузии.The main aim of the work is a theoretical study of diffusion (flow of particles, chains of particles) in bidisperse magnetic fluids with chain aggregates. Firstly, we study diffusion properties of a monodisperse ferrofluid, and then we extend this theory on bidisperse models. In a result, dependence of diffusion properties on a system polydispersity will be studied. An influence of granulometric composition on diffusion coefficient behavior will be studied.Программа развития УрФУ на 2013 год (п.1.2.2.3
Transmission-blocking activity induced by malaria vaccine candidates Pfs25/Pvs25 is a direct and predictable function of antibody titer
<p>Abstract</p> <p>Background</p> <p>Mosquito stage malaria vaccines are designed to induce an immune response in the human host that will block the parasite's growth in the mosquito and consequently block transmission of the parasite. A mosquito membrane-feeding assay (MFA) is used to test transmission-blocking activity (TBA), but in this technique cannot accommodate many samples. A clear understanding of the relationship between antibody levels and TBA may allow ELISA determinations to be used to predict TBA and assist in planning vaccine development.</p> <p>Methods</p> <p>Rabbit anti-Pfs25 sera and monkey anti-Pvs25 sera were generated and the antibody titers were determined by a standardized ELISA. The biological activity of the same sera was tested by MFA using <it>Plasmodium </it>gametocytes (cultured <it>Plasmodium falciparum </it>or <it>Plasmodium vivax </it>from malaria patients) and <it>Anopheles </it>mosquitoes.</p> <p>Results</p> <p>Anti-Pfs25 and anti-Pvs25 sera showed that ELISA antibody units correlate with the percent reduction in the oocyst density per mosquito (Spearman Rank correlations: 0.934 and 0.616, respectively), and fit a hyperbolic curve when percent reduction in oocyst density is plotted against antibody units of the tested sample. Antibody levels also correlated with the number of mosquitoes that failed to become infected, and this proportion can be calculated from the reduction in oocyst numbers and the distribution of oocysts per infected mosquito in control group.</p> <p>Conclusion</p> <p>ELISA data may be used as a surrogate for the MFA to evaluate transmission-blocking vaccine efficacy. This will facilitate the evaluation of transmission-blocking vaccines and implementation of this malaria control strategy.</p
Substantiation of thermomechanical technology parameters of absorbing levels isolation of the boreholes
The aim of the work is to improve the thermomechanical absorption insulation technology horizons of drilling wells by the established regularities of change and the substantiation of its regime parameters from the composition and physical-mechanical properties strengthen thermoplastic composite material and, on this basis, development a technological regulation containing recommendations on the manufacture of composites and organizations laying work, designing and isolation of the absorption zones of the washing liquid in the drilling rigs wells. The tasks set were solved by complex method research that contains analysis and synthesis of literary and patent sources, conducting analytical, experimental and industrial research. Experimental processing data was carried out using methods of mathematical statistics. Experimental research is carried out using the provisions of the theory of scientific experiment and theory random processes. The evaluation of the effectiveness of the results was carried out in production conditions
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Solar neutrino with Borexino: results and perspectives
Borexino is a unique detector able to perform measurement of solar neutrinos
fluxes in the energy region around 1 MeV or below due to its low level of
radioactive background. It was constructed at the LNGS underground laboratory
with a goal of solar Be neutrino flux measurement with 5\% precision. The
goal has been successfully achieved marking the end of the first stage of the
experiment. A number of other important measurements of solar neutrino fluxes
have been performed during the first stage. Recently the collaboration
conducted successful liquid scintillator repurification campaign aiming to
reduce main contaminants in the sub-MeV energy range. With the new levels of
radiopurity Borexino can improve existing and challenge a number of new
measurements including: improvement of the results on the Solar and terrestrial
neutrino fluxes measurements; measurement of pp and CNO solar neutrino fluxes;
search for non-standard interactions of neutrino; study of the neutrino
oscillations on the short baseline with an artificial neutrino source (search
for sterile neutrino) in context of SOX project.Comment: 15 pages, 4 figure
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New experimental limits on the Pauli forbidden transitions in C nuclei obtained with 485 days Borexino data
The Pauli exclusion principle (PEP) has been tested for nucleons () in
with the Borexino detector.The approach consists of a search for
, , and emitted in a non-Paulian transition of
1- shell nucleons to the filled 1 shell in nuclei. Due to the
extremely low background and the large mass (278 t) of the Borexino detector,
the following most stringent up-to-date experimental bounds on PEP violating
transitions of nucleons have been established:
y, y,
y,
y and y, all at 90% C.L. The corresponding upper
limits on the relative strengths for the searched non-Paulian electromagnetic,
strong and weak transitions have been estimated: , and .Comment: 9 pages, 6 figure
Recent Borexino results and prospects for the near future
The Borexino experiment, located in the Gran Sasso National Laboratory, is an
organic liquid scintillator detector conceived for the real time spectroscopy
of low energy solar neutrinos. The data taking campaign phase I (2007 - 2010)
has allowed the first independent measurements of 7Be, 8B and pep fluxes as
well as the first measurement of anti-neutrinos from the earth. After a
purification of the scintillator, Borexino is now in phase II since 2011. We
review here the recent results achieved during 2013, concerning the seasonal
modulation in the 7Be signal, the study of cosmogenic backgrounds and the
updated measurement of geo-neutrinos. We also review the upcoming measurements
from phase II data (pp, pep, CNO) and the project SOX devoted to the study of
sterile neutrinos via the use of a 51Cr neutrino source and a 144Ce-144Pr
antineutrino source placed in close proximity of the active material.Comment: 8 pages, 11 figures. To be published as proceedings of Rencontres de
Moriond EW 201
Measurement of the solar 8B neutrino rate with a liquid scintillator target and 3 MeV energy threshold in the Borexino detector
We report the measurement of electron neutrino elastic scattering from 8B
solar neutrinos with 3 MeV energy threshold by the Borexino detector in Gran
Sasso (Italy). The rate of solar neutrino-induced electron scattering events
above this energy in Borexino is 0.217 +- 0.038 (stat) +- 0.008 (syst) cpd/100
t, which corresponds to the equivalent unoscillated flux of (2.4 +- 0.4 (stat)
+- 0.1 (syst))x10^6 cm^-2 s^-1, in good agreement with measurements from SNO
and SuperKamiokaNDE. Assuming the 8B neutrino flux predicted by the high
metallicity Standard Solar Model, the average 8B neutrino survival probability
above 3 MeV is measured to be 0.29+-0.10. The survival probabilities for 7Be
and 8B neutrinos as measured by Borexino differ by 1.9 sigma. These results are
consistent with the prediction of the MSW-LMA solution of a transition in the
solar electron neutrino survival probability between the low energy
vacuum-driven and the high-energy matter-enhanced solar neutrino oscillation
regimes.Comment: 10 pages, 8 figures, 6 table
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Search for Solar Axions Produced in Reaction with Borexino Detector
A search for 5.5-MeV solar axions produced in the reaction was performed using the Borexino detector. The Compton
conversion of axions to photons, ; the
axio-electric effect, ; the decay of axions into
two photons, ; and inverse Primakoff conversion on
nuclei, , are considered. Model independent
limits on axion-electron (), axion-photon (), and
isovector axion-nucleon () couplings are obtained: and at 1 MeV (90% c.l.). These limits are
2-4 orders of magnitude stronger than those obtained in previous
laboratory-based experiments using nuclear reactors and accelerators.Comment: 11 pages, 7 figures, submitted to Phys.Rev.
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Spectroscopy of geo-neutrinos from 2056 days of Borexino data
We report an improved geo-neutrino measurement with Borexino from 2056 days
of data taking. The present exposure is
protonyr. Assuming a chondritic Th/U mass ratio of 3.9, we obtain geo-neutrino events. The null
observation of geo-neutrinos with Borexino alone has a probability of (5.9). A geo-neutrino signal from the mantle is
obtained at 98\% C.L. The radiogenic heat production for U and Th from the
present best-fit result is restricted to the range 23-36 TW, taking into
account the uncertainty on the distribution of heat producing elements inside
the Earth.Comment: 4 pages, 4 figure
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Measurement of geo-neutrinos from 1353 days of Borexino
We present a measurement of the geo--neutrino signal obtained from 1353 days
of data with the Borexino detector at Laboratori Nazionali del Gran Sasso in
Italy. With a fiducial exposure of (3.69 0.16) proton
year after all selection cuts and background subtraction, we detected
(14.3 4.4) geo-neutrino events assuming a fixed chondritic mass Th/U
ratio of 3.9. This corresponds to a geo-neutrino signal = (38.8
12.0) TNU with just a 6 probability for a null geo-neutrino
measurement. With U and Th left as free parameters in the fit, the relative
signals are = (10.6 12.7) TNU and =
(26.5 19.5) TNU. Borexino data alone are compatible with a mantle
geo--neutrino signal of (15.4 12.3) TNU, while a combined analysis with
the KamLAND data allows to extract a mantle signal of (14.1 8.1) TNU. Our
measurement of a reactor anti--neutrino signal =
84.5 TNU is in agreement with expectations in the presence of
neutrino oscillations.Comment: 9 pages, 6 figure
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