97 research outputs found
Non-obvious Problems in Clark Electrode Application at Elevated Temperature and Ways of Their Elimination
Well-known cause of frequent failures of closed oxygen sensors is the appearance of gas bubbles in the electrolyte. The problem is traditionally associated with insufficient sealing of the sensor that is not always true. Study of a typical temperature regime of measurement system based on Clark sensor showed that spontaneous release of the gas phase is a natural effect caused by periodic warming of the sensor to a temperature of the test liquid. The warming of the sensor together with the incubation medium causes oversaturation of electrolyte by dissolved gases and the allocation of gas bubbles. The lower rate of sensor heating in comparison with the medium reduces but does not eliminate the manifestation of this effect. It is experimentally established, that with each cycle of heating of measuring system up to 37 ∘ C followed by cooling the volume of gas phase in the electrolyte (KCl; 60 g/L; 400 L) increased by 0.6 L approximately. Thus, during just several cycles it can dramatically degrade the characteristics of the sensor. A method was developed in which the oxygen sensor is heated in contact with the liquid, (depleted of dissolved gases), allowing complete exclusion of the above-mentioned effect
Immunobiological Characteristics of Cholera Toxin B-Subunit
Carried out was immunobiological evaluation of cholera toxin B subunit preparations obtained using different experimental and production methods. It was demonstrated that B subunit preparations were non-toxic for biomodels and did not cause significant pathological alterations in their organs and tissues. They also did not alter the condition of immunocompetent cells at different stages of their cycle, and promote anti-toxic antibodies production. Thus, B subunit preparations under study can be considered as promising components of cholera vaccine
Anesthesia of laboratory animals in manufacturing of diagnostic and preventive biomedicines
Preparations such as XilaVet, Zoletil 100 as well as Aeranne (Isoflurane) are successfully applied for animal anesthesia in veterinary practice. We assessed a possibility of using parenteral narcosis with Zoletil 100 in combination with muscle relaxant Xila for producer-rabbits involved in manufacturing of natural rabbit serum subsequently deployed for production of diagnostic serum and immunoglobulin preparations. Administration of preparations into auricular vein is easy to do, while animals are sedated immediately allowing for safe fixation on restraining table and causing no additional stress for biomodels. This type of narcosis provides for expected depth of anesthesia and its maintenance until the end of blood-letting procedure. Parameters characterizing the state of cardiovascular system due to anesthetic products remained within the permitted limits. These preparations do not reduce heart beat rate allowing for collecting sufficient blood volumes. Application of inhalation anesthesia with Aeranne in laboratory animals provides for the specified depth of anesthesia and its maintenance until the end of the whole procedure. However, it requires specialized equipment and highly trained personnel with appropriate skills. Usage of Xila as a mono narcosis is not recommended as exhibits weak analgesic effects and strong hypotensive activity by decreasing quantity of collected blood volume. It was found that anesthetics such as Xila, Zoletil 100, Aeranne did not affect specific activity of immune sera in case of total dehematizing procedure. Moreover, antibody titers were not declined throughout entire observation (12 months) period and complied with the requirements of regulatory documentation. In addition, a feasibility of replacing old-fashioned anesthesia method with diethyl ether for a combination of safer contemporary preparations of Zoletil 100 and Xila was demonstrated while manufacturing tableted chemical cholera vaccine in experimental series with suckling rabbits used at diverse stages of raw material verification during surgical interventions. Xila, Zoletil 100, and Aeranne examined by us had no impact on the amount of blood obtained from donor-animals, immunological properties of the sera and ready-to-use diagnostic preparations. Such drugs were safe for all-age animals that comply with the requirements to anesthesia of animal biomodels and producer-animals in manufacturing of immunobiological preparations. Thus, our study allowed to conduct experiments with laboratory animals in a more humane manner
Prospects for Application of Ultrafiltration Technology for the Scaled Preparation of Plague Microbe and Cholera Vibrio Major Antigens
Demonstrated is the possibility of application of ultrafiltration technologies in the process of cholera toxin and plague agent capsular antigen precipitation under production conditions. Application of ultrafiltration techniques permits of the reduction of losses at the stages of isolation and purification of antigen preparations; and concentration of raw material or semi-finished product provides for the reduction of labor inputs. Thus it leads to the increase in productivity and economical efficiency
The Hamburg/ESO R-process Enhanced Star survey (HERES). V. Detailed abundance analysis of the r-process enhanced star HE 2327-5642
We report on a detailed abundance analysis of the strongly r-process enhanced
giant star, HE 2327-5642 ([Fe/H] = -2.78, [r/Fe] = +0.99). Determination of
stellar parameters and element abundances was based on analysis of high-quality
VLT/UVES spectra. The surface gravity was calculated from the NLTE ionization
balance between Fe I and Fe II, and Ca I and Ca II. Accurate abundances for a
total of 40 elements and for 23 neutron-capture elements beyond Sr and up to Th
were determined. The heavy element abundance pattern of HE 2327-5642 is in
excellent agreement with those previously derived for other strongly r-process
enhanced stars. Elements in the range from Ba to Hf match the scaled Solar
r-process pattern very well. No firm conclusion can be drawn with respect to a
relationship between the fisrt neutron-capture peak elements, Sr to Pd, in HE
2327-5642 and the Solar r-process, due to the uncertainty of the latter. A
clear distinction in Sr/Eu abundance ratios was found between the halo stars
with different europium enhancement. The strongly r-process enhanced stars
reveal a low Sr/Eu abundance ratio at [Sr/Eu] = -0.92+-0.13, while the stars
with 0 < [Eu/Fe] < 1 and [Eu/Fe] < 0 have 0.36 dex and 0.93 dex larger Sr/Eu
values, respectively. Radioactive dating for HE 2327-5642 with the observed
thorium and rare-earth element abundance pairs results in an average age of
13.3 Gyr, when based on the high-entropy wind calculations, and 5.9 Gyr, when
using the Solar r-residuals. HE 2327-5642 is suspected to be radial-velocity
variable based on our high-resolution spectra, covering ~4.3 years.Comment: 16 pages, 12 figures, accepted to A&
The Chemical Composition of Two Supergiants in the Dwarf Irregular Galaxy WLM
[Abridged] The chemical composition of two stars in WLM has been determined
from high quality UVES data obtained at the VLT UT2 (program 65.N-0375). The
model atmospheres analysis shows that they have the same metallicity, [Fe/H] =
-0.38 +/-0.20, and [Mg/Fe] = -0.24 +/-0.16. This result suggests that the
[alpha(Mg)/Fe] ratio in WLM may be suppressed relative to solar abundances
(also supported by differential abundances relative to similar stars in NGC6822
and the SMC). The absolute Mg abundance, [Mg/H] = -0.62 is high relative to
what is expected from the nebulae though, where two independent spectroscopic
analyses of the HII regions in WLM yield [O/H] = -0.89. Intriguingly, the
oxygen abundance determined from the OI 6158 feature in one WLM star is [O/H] =
-0.21 +/-0.10, corresponding to five times higher than the nebular oxygen
abundance. This is the first time that a significant difference between young
stellar and nebular oxygen abundances has been found, and presently, there is
no simple explanation for this difference. If the stellar abundances reflect
the true composition of WLM, then this galaxy lies well above the
metallicity-luminosity relationship for dwarf irregular galaxies. It also
suggests that WLM is more chemically evolved than currently interpreted from
its color-magnitude diagram.Comment: 27 pages, 7 tables, 10 figures. accepted for publication in the
Astronomical Journa
Non-obvious Problems in Clark Electrode Application at Elevated Temperature and Ways of Their Elimination
Well-known cause of frequent failures of closed oxygen sensors is the appearance of gas bubbles in the electrolyte. The problem is traditionally associated with insufficient sealing of the sensor that is not always true. Study of a typical temperature regime of measurement system based on Clark sensor showed that spontaneous release of the gas phase is a natural effect caused by periodic warming of the sensor to a temperature of the test liquid. The warming of the sensor together with the incubation medium causes oversaturation of electrolyte by dissolved gases and the allocation of gas bubbles. The lower rate of sensor heating in comparison with the medium reduces but does not eliminate the manifestation of this effect. It is experimentally established, that with each cycle of heating of measuring system up to 37°C followed by cooling the volume of gas phase in the electrolyte (KCl; 60 g/L; 400 μL) increased by 0.6 μL approximately. Thus, during just several cycles it can dramatically degrade the characteristics of the sensor. A method was developed in which the oxygen sensor is heated in contact with the liquid, (depleted of dissolved gases), allowing complete exclusion of the above-mentioned effect
- …