45 research outputs found
POSSIBILITIES OF PURIFICATION OF HEAVY METALS CONTAMINATION IN SOILS
Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals.Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals
BIOREMEDIATION OF SOILS CONTAMINATED WITH HEAVY METALS
Waste generated due to the growth of the modern industry is undergoing natural disposal in the environment for a long period of time. A special danger is caused by heavy metals that do not undergo biodegradation. Known purification methods of soils are not always effective and profitable. Correct selection of soil remediation methods contaminated with heavy metals ensures effective cleaning and restoration of soils. For this purpose, selecting representatives of various taxonomic groups of microorganisms binding heavy metals in the soil is carrying out. A complex method of purification of soils contaminated with have metals is being developed. Modified forms of humic acids were developed, geochemical barriers using local clays were created. Works to biostimulate local microorganisms required for bioremediation of soils contaminated with heavy metals are conducted. Remediation and increasing the fertility of soils contaminated with heavy metals are necessary for the prevention of further penetration of these metals into agricultural crops.Waste generated due to the growth of the modern industry is undergoing natural disposal in the environment for a long period of time. A special danger is caused by heavy metals that do not undergo biodegradation. Known purification methods of soils are not always effective and profitable. Correct selection of soil remediation methods contaminated with heavy metals ensures effective cleaning and restoration of soils. For this purpose, selecting representatives of various taxonomic groups of microorganisms binding heavy metals in the soil is carrying out. A complex method of purification of soils contaminated with have metals is being developed. Modified forms of humic acids were developed, geochemical barriers using local clays were created. Works to biostimulate local microorganisms required for bioremediation of soils contaminated with heavy metals are conducted. Remediation and increasing the fertility of soils contaminated with heavy metals are necessary for the prevention of further penetration of these metals into agricultural crops
Puzzling Low-Frequency Variations in the δ Scuti-type Kepler Star KIC 5988140 (HD 188774)
At first sight, the Kepler data of the A-type star KIC 5988140 mimics the
light curve of an eclipsing binary system with a superposed short-period variability of
type δ Scuti. It was attributed by the Kepler Asteroseismology Consortium (KASC)
to the working group “Binary and Multiple Stars”, where we picked it up. We used
the high-quality space photometry supplemented by recent high-resolution spectra to
investigate the cause of the variability of this late A-type object. We considered three
different possible scenarios: (1) binarity, (2) co-existence of γ Doradus and delta Scuti
pulsations (the hybrid case) and (3) rotation of the stellar surface with an asymmetric intensity distribution (i.e. rotational modulation). We confirm the presence of various pressure modes of type delta Scuti. However, none of the previous scenarios is capable of reproducing all of the observed characteristics of the variations. Thus, the cause of the remaining light and radial velocity variations remains presently unexplained by any of the considered physical processes
The GRANDMA network in preparation for the fourth gravitational-wave observing run
GRANDMA is a world-wide collaboration with the primary scientific goal ofstudying gravitational-wave sources, discovering their electromagneticcounterparts and characterizing their emission. GRANDMA involves astronomers,astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now atruly global network of telescopes, with (so far) 30 telescopes in bothhemispheres. It incorporates a citizen science programme (Kilonova-Catcher)which constitutes an opportunity to spread the interest in time-domainastronomy. The telescope network is an heterogeneous set of already-existingobserving facilities that operate coordinated as a single observatory. Withinthe network there are wide-field imagers that can observe large areas of thesky to search for optical counterparts, narrow-field instruments that dotargeted searches within a predefined list of host-galaxy candidates, andlarger telescopes that are devoted to characterization and follow-up of theidentified counterparts. Here we present an overview of GRANDMA after the thirdobserving run of the LIGO/VIRGO gravitational-wave observatories in and its ongoing preparation for the forthcoming fourth observational campaign(O4). Additionally, we review the potential of GRANDMA for the discovery andfollow-up of other types of astronomical transients.<br
Ready for O4 II: GRANDMA Observations of Swift GRBs during eight-weeks of Spring 2022
We present a campaign designed to train the GRANDMA network and its
infrastructure to follow up on transient alerts and detect their early
afterglows. In preparation for O4 II campaign, we focused on GRB alerts as they
are expected to be an electromagnetic counterpart of gravitational-wave events.
Our goal was to improve our response to the alerts and start prompt
observations as soon as possible to better prepare the GRANDMA network for the
fourth observational run of LIGO-Virgo-Kagra (which started at the end of May
2023), and future missions such as SM. To receive, manage and send out
observational plans to our partner telescopes we set up dedicated
infrastructure and a rota of follow-up adcates were organized to guarantee
round-the-clock assistance to our telescope teams. To ensure a great number of
observations, we focused on Swift GRBs whose localization errors were generally
smaller than the GRANDMA telescopes' field of view. This allowed us to bypass
the transient identification process and focus on the reaction time and
efficiency of the network. During 'Ready for O4 II', 11 Swift/INTEGRAL GRB
triggers were selected, nine fields had been observed, and three afterglows
were detected (GRB 220403B, GRB 220427A, GRB 220514A), with 17 GRANDMA
telescopes and 17 amateur astronomers from the citizen science project
Kilonova-Catcher. Here we highlight the GRB 220427A analysis where our
long-term follow-up of the host galaxy allowed us to obtain a photometric
redshift of , its lightcurve elution, fit the decay slope of the
afterglows, and study the properties of the host galaxy
Multi-band analyses of the bright GRB~230812B and the associated SN2023pel
GRB~230812B is a bright and relatively nearby () long gamma-ray
burst that has generated significant interest in the community and therefore
has been subsequently observed over the entire electromagnetic spectrum. We
report over 80 observations in X-ray, ultraviolet, optical, infrared, and
sub-millimeter bands from the GRANDMA (Global Rapid Advanced Network for
Multi-messenger Addicts) network of observatories and from observational
partners. Adding complementary data from the literature, we then derive
essential physical parameters associated with the ejecta and external
properties (i.e. the geometry and environment) and compare with other analyses
of this event (e.g. Srinivasaragavan et al. 2023). We spectroscopically confirm
the presence of an associated supernova, SN2023pel, and we derive a
photospheric expansion velocity of v 17 km . We
analyze the photometric data first using empirical fits of the flux and then
with full Bayesian Inference. We again strongly establish the presence of a
supernova in the data, with an absolute peak r-band magnitude . We find a flux-stretching factor or relative brightness and a time-stretching factor ,
both compared to SN1998bw. Therefore, GRB 230812B appears to have a clear long
GRB-supernova association, as expected in the standard collapsar model.
However, as sometimes found in the afterglow modelling of such long GRBs, our
best fit model favours a very low density environment (). We also find small values for
the jet's core angle and
viewing angle. GRB 230812B/SN2023pel is one of the best characterized
afterglows with a distinctive supernova bump
GRANDMA and HXMT Observations of GRB 221009A -- the Standard-Luminosity Afterglow of a Hyper-Luminous Gamma-Ray Burst
GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50
years of study. In this paper, we present observations in the X-ray and optical
domains after the GRB obtained by the GRANDMA Collaboration (which includes
observations from more than 30 professional and amateur telescopes) and the
Insight-HXMT Collaboration. We study the optical afterglow with empirical
fitting from GRANDMA+HXMT data, augmented with data from the literature up to
60 days. We then model numerically, using a Bayesian approach, the GRANDMA and
HXMT-LE afterglow observations, that we augment with Swift-XRT and additional
optical/NIR observations reported in the literature. We find that the GRB
afterglow, extinguished by a large dust column, is most likely behind a
combination of a large Milky-Way dust column combined with moderate
low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset,
we find that the simplest model, where the observed afterglow is produced by
synchrotron radiation at the forward external shock during the deceleration of
a top-hat relativistic jet by a uniform medium, fits the multi-wavelength
observations only moderately well, with a tension between the observed temporal
and spectral evolution. This tension is confirmed when using the extended
dataset. We find that the consideration of a jet structure (Gaussian or
power-law), the inclusion of synchrotron self-Compton emission, or the presence
of an underlying supernova do not improve the predictions, showing that the
modelling of GRB22109A will require going beyond the most standard GRB
afterglow model. Placed in the global context of GRB optical afterglows, we
find the afterglow of GRB 221009A is luminous but not extraordinarily so,
highlighting that some aspects of this GRB do not deviate from the global known
sample despite its extreme energetics and the peculiar afterglow evolution.Comment: Accepted to ApJL for the special issue, 37 pages, 23 pages main text,
6 tables, 13 figure
Inhibition of the DNA-dependent protein kinase catalytic subunit by RNAi makes HeLa cells more prone to gene amplification.
Possibilities Of Purification Of Heavy Metals Contamination In Soils
Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals