2,056 research outputs found
Electric Switching of the Charge-Density-Wave and Normal Metallic Phases in Tantalum Disulfide Thin-Film Devices
We report on switching among three charge-density-wave phases - commensurate,
nearly commensurate, incommensurate - and the high-temperature normal metallic
phase in thin-film 1T-TaS2 devices induced by application of an in-plane
electric field. The electric switching among all phases has been achieved over
a wide temperature range, from 77 K to 400 K. The low-frequency electronic
noise spectroscopy has been used as an effective tool for monitoring the
transitions, particularly the switching from the incommensurate
charge-density-wave phase to the normal metal phase. The noise spectral density
exhibits sharp increases at the phase transition points, which correspond to
the step-like changes in resistivity. Assignment of the phases is consistent
with low-field resistivity measurements over the temperature range from 77 K to
600 K. Analysis of the experimental data and calculations of heat dissipation
suggest that Joule heating plays a dominant role in the electric-field induced
transitions in the tested 1T-TaS2 devices on Si/SiO2 substrates. The
possibility of electrical switching among four different phases of 1T-TaS2 is a
promising step toward nanoscale device applications. The results also
demonstrate the potential of noise spectroscopy for investigating and
identifying phase transitions in materials.Comment: 32 pages, 7 figure
Nuclear deformation and the two neutrino double-\beta decay in ^{124,126}Xe,^{128,130}Te, ^{130,132}Ba and ^{150}Nd isotopes
The two neutrino double beta decay of Xe,Te, Ba and Nd isotopes is studied in the Projected
Hartree-Fock-Bogoliubov (PHFB) model. Theoretical 2
half-lives of Te, and Nd isotopes, and 2, 2 and 2 for Xe and Ba nuclei are presented. Calculated quadrupolar
transition probabilities B(E2: ), static quadrupole moments and
factors in the parent and daughter nuclei reproduce the experimental
information, validating the reliability of the model wave functions. The
anticorrelation between nuclear deformation and the nuclear transition matrix
element is confirmed.Comment: 19 page
Estimated Inpatient Hospital Stay in Individual Wards: Guidelines on Radiation Safety after Radioiodine Therapy
Radionuclide therapy safety requirements are regulated by the Russian Radiation Safety Standards (RRSS), which state the maximum allowed radionuclide activity in the body and the equivalent dose rate (EDR) of gamma radiation. Therefore, it is necessary to estimate the time of an inpatient hospital stay in specially designed radionuclide therapy wards. The article presents the findings of individual 131I biokinetics studies in 64 patients admitted to radioiodine therapy of thyrotoxicosis and differentiated thyroid cancer. We developed a method to calculate the time interval to reach the EDR of 20μSv/h and the recommended EDR of 3 and 0.3μSv/h for adults and children, respectively. It is based on the measurement of the 131I excretion constant.
Keywords: Radioiodine therapy, Radiation safety, Guidelin
DDAO Controlled Synthesis of Organo-Modified Silica Nanoparticles with Encapsulated Fluorescent Boron Dipyrrins and Study of Their Uptake by Cancerous Cells
The design of cargo carriers with high biocompatibility, unique morphological characteristics, and capability of strong bonding of fluorescent dye is highly important for the development of a platform for smart imaging and diagnostics. In this paper, BODIPY-doped silica nanoparticles were prepared through a "one-pot" soft-template method using a sol-gel process. Several sol-gel precursors have been used in sol-gel synthesis in the presence of soft-template to obtain the silica-based materials with the most appropriate morphological features for the immobilization of BODIPY molecules. Obtained silica particles have been shown to be non-cytotoxic and can be effectively internalized into the cervical cancer cell line (HeLa). The described method of synthesis allows us to obtain silica-based carriers with an immobilized fluorescent dye that provide the possibility for real-time imaging and detection of these carriers
Lipid Peroxidation in the Pre-Reactive Period of Cold Injury
Pathological processes in the pre-reactive period of cold injury have not been studied.The purpose of this study is to assess the morphological and biochemical parameters of blood in the body of patients in the pre-reactive period of cold injury.Material and methods. We examined patients with cold injury in the pre-reactive period. Determined: diene conjugates, malonic dialdehyde, the total content of low molecular weight antioxidants, superoxide dismutase activity, catalase,glutathione peroxidase, glutathione reductase, using a SPECORD 40 spectrophotometer. The serum biochemical parameters in the serum were determined by biochemical automator analysis. Statistical processing of the data was performed using IBM SPSS Statistics 19.Results and discussion. Features of the biochemical profile of blood in the pre-reactive period of cold injury in the human body are an increase in concentration of glucose and triacylglycerides in blood, an increase in transaminase activity, as aresult of inflammatory and destructive processes, a decrease in the cholesterol concentration in the blood of patients. At the same time, the pre-reactive period of cold injury is characterized by an increase in monocytes compared with the control, which, in combination with hypoxia, leads to an intensification of lipid peroxidation processes. In addition, the antioxidant protection in the pre-reactive period in the body of patients increased slightly.Conclusion. According to the results of our research, already at the stage of the pre-reactive period of cold injury there is a significant intensification of free radical lipid oxidation processes
Transition from Fireball to Poynting-flux-dominated Outflow in Three-Episode GRB 160625B
The ejecta composition is an open question in gamma-ray bursts (GRB) physics.
Some GRBs possess a quasi-thermal spectral component in the time-resolved
spectral analysis, suggesting a hot fireball origin. Others show a featureless
non-thermal spectrum known as the "Band" function, consistent with a
synchrotron radiation origin and suggesting that the jet is
Poynting-flux-dominated at the central engine and likely in the emission region
as well. There are also bursts showing a sub-dominant thermal component and a
dominant synchrotron component suggesting a likely hybrid jet composition. Here
we report an extraordinarily bright GRB 160625B, simultaneously observed in
gamma-rays and optical wavelengths, whose prompt emission consists of three
isolated episodes separated by long quiescent intervals, with the durations of
each "sub-burst" being 0.8 s, 35 s, and 212 s, respectively. Its high
brightness (with isotropic peak luminosity L
erg/s) allows us to conduct detailed time-resolved spectral analysis in each
episode, from precursor to main burst and to extended emission. The spectral
properties of the first two sub-bursts are distinctly different, allowing us to
observe the transition from thermal to non-thermal radiation between
well-separated emission episodes within a single GRB. Such a transition is a
clear indication of the change of jet composition from a fireball to a
Poynting-flux-dominated jet.Comment: Revised version reflecting the referees' comments. 27 pages, 11
figures, 5 tables. The final edited version will appear in Nature Astronom
GRB 070518: A Gamma-ray Burst with Optically Dim Luminosity
We present our optical observations of {\em Swift} GRB 070518 afterglow
obtained at the 0.8-m Tsinghua University-National Astronomical Observatory of
China telescope (TNT) at Xinglong Observatory. Our follow-up observations were
performed from 512 sec after the burst trigger. With the upper limit of
redshift 0.7, GRB 070518 is found to be an optically dim burst. The
spectra indices of optical to X-ray are slightly larger than 0.5,
which implies the burst might be a dark burst. The extinction of the
host galaxy is 3.2 mag inferred from the X-ray hydrogen column density with
Galactic extinction law, and 0.3 mag with SMC extinction law. Also, it is
similar to three other low-redshift optically dim bursts, which belong to XRR
or XRF, and mid-term duration(, except for GRB 070419A,
=116s). Moreover, its band afterglow flux is well fitted by a
single power-law with an index of 0.87. The optical afterglow and the X-ray
afterglow in the normal segment might have the same mechanism, as they are
consistent with the prediction of the classical external shock model. Besides,
GRB 070518 agrees with Amati relation under reasonable assumptions. The
Ghirlanda relation is also tested with the burst.Comment: 8 pages, 4 figures, MNRAS accepte
- …