Natural antimony targets were irradiated in a 60 MeV bremsstrahlung beam and gamma spectrometric measurements were performed. The goal was to establish the yield of 117mSn, a radionuclide with great ...potential for application in medicine. Considering that 117mSn is predominantly produced through a photonuclear reaction in which an charged particle is emitted (121Sb(γ,p3n)), the yield of this tin isotope is much lower than the yields of several antimony isotopes produced in (γ,xn) reactions. It has been estimated that photonuclear reactions on natural antimony could produce 117mSn activities needed for therapeutic applications, with accelerators having electron currents of the order of mA. For the used bremsstrahlung energy of 60 MeV, it was estimated how much 119mSn activity can be expected when exposing the antimony target.
•Natural Sb targets were exposed to 60 MeV bremsstrahlung.•Yield of 117mSn was determined using gamma spectroscopy.•It is estimated that (γ,xn) reaction can be used for production of 117mSn for medical purpose.
The analysis of gamma spectra obtained from the decay of
Au indicated that a ten times higher value was adopted for the quantum yield of the transition of 521.4 keV. Based on the intensity of gamma ...lines corresponding to well-known transitions, the quantum yield for the 521.4 keV transition was calculated. The obtained value was used to correct the adopted value of the intensity of the beta transition that populates 877.0 keV energy state from which gamma radiation of 521.4 keV is emitted.
Samples made from natural bismuth were exposed in 60 MeV end-point bremsstrahlung beam. In this paper, a simple model for determination the share of two ways of
203
Pb formation: by the decay of
203
...Bi, produced in
209
Bi(γ,6n)
203
Bi reaction and by
209
Bi(γ,p 5n)
203
Pb reaction is described. The method employs the ratio of
203
Pb and
203
Bi nuclei numbers and activities at the end of the exposure as the input value. This ratio was estimated from gamma spectra measured after irradiation of natural Bi sample. It was found that the rate of production of
203
Pb by
209
Bi(γ,p 5n)
203
Pb reaction is about 6% of the
203
Bi production rate in the
209
Bi(γ,6n)
203
Bi reaction. Obtained result is compared with TALYS based estimation.
Machine learning is bringing us self-driving cars, medical diagnoses, and language translation, but how can machine learning help marketers improve marketing decisions? Machine learning models ...predict extremely well, are scalable to “big data,” and are a natural fit to analyze rich media content, such as text, images, audio, and video. Examples of current marketing applications include identification of customer needs from online data, accurate prediction of consumer response to advertising, personalized pricing, and product recommendations. But without the human input and insight—the soul—the applications of machine learning are limited. To create competitive or cooperative strategies, to generate creative product designs, to be accurate for “whatif” and “but-for” applications, to devise dynamic policies, to advance knowledge, to protect consumer privacy, and avoid algorithm bias, machine learning needs a soul. The brightest future is based on the synergy of what the machine can do well and what humans do well. We provide examples and predictions for the future.
We studied the effects of irradiation with protons at doses of 1 and 2 Gy in the Bragg Peak with an energy of 170 MeV on learning, recall of skills, and concentration of monoamines and their ...metabolites in the prefrontal cortex, nucleus accumbens, hypothalamus, striatum, and hippocampus of rats. In the T-maze, we performed discriminant learning with food reinforcement. Rats were trained for 5 days; from the second to fifth days, we found a considerable level of learning as compared to the first day. After training, on the sixth day, we found a trend to a decrease in the efficacy of test performance, which achieved significant differences on the seventh day of testing. Irradiation by protons at doses of 1 and 2 Gy in the Bragg peak did not influence the elaboration and recall of the passive avoidance reflex. This treatment causes a decrease in the concentration of catecholamines in the prefrontal cortex and 3-MT, a metabolite of dopamine, in the striatum. On the basis of disturbances of neurochemical indices in the corresponding brain structures, it is possible to logically explain the observed disturbances in behavior.
Natural antimony targets were irradiated in a 60 MeV bremsstrahlung beam and gamma spectrometric measurements were performed. The goal was to establish the yield of
Sn, a radionuclide with great ...potential for application in medicine. Considering that
Sn is predominantly produced through a photonuclear reaction in which an charged particle is emitted (
Sb(γ,p3n)), the yield of this tin isotope is much lower than the yields of several antimony isotopes produced in (γ,xn) reactions. It has been estimated that photonuclear reactions on natural antimony could produce
Sn activities needed for therapeutic applications, with accelerators having electron currents of the order of mA. For the used bremsstrahlung energy of 60 MeV, it was estimated how much
Sn activity can be expected when exposing the antimony target.
Abstract
Nuclear nanomedicine, with its targeting ability and heavily loading capacity, along with its enhanced retention to avoid rapid clearance as faced with molecular radiopharmaceuticals, ...provides unique opportunities to treat tumors and metastasis. Despite these promises, this field has seen limited activities, primarily because of a lack of suitable nanocarriers, which are safe, excretable and have favorable pharmacokinetics to efficiently deliver and retain radionuclides in a tumor. Here, we introduce biodegradable laser-synthesized Si nanoparticles having round shape, controllable low-dispersion size, and being free of any toxic impurities, as highly suitable carriers of therapeutic
188
Re radionuclide. The conjugation of the polyethylene glycol-coated Si nanoparticles with radioactive
188
Re takes merely 1 hour, compared to its half-life of 17 hours. When intravenously administered in a Wistar rat model, the conjugates demonstrate free circulation in the blood stream to reach all organs and target tumors, which is radically in contrast with that of the
188
Re salt that mostly accumulates in the thyroid gland. We also show that the nanoparticles ensure excellent retention of
188
Re in tumor, not possible with the salt, which enables one to maximize the therapeutic effect, as well as exhibit a complete time-delayed conjugate bioelimination. Finally, our tests on rat survival demonstrate excellent therapeutic effect (72% survival compared to 0% of the control group). Combined with a series of imaging and therapeutic functionalities based on unique intrinsic properties of Si nanoparticles, the proposed biodegradable complex promises a major advancement in nuclear nanomedicine.
ExoMars is a two-launch mission undertaken by Roscosmos and European Space Agency. Trace Gas Orbiter, a satellite part of the 2016 launch carries the Fine Resolution Neutron Detector instrument as ...part of its payload. The instrument aims at mapping hydrogen content in the upper meter of Martian soil with spatial resolution between 60 and 200 km diameter spot. This resolution is achieved by a collimation module that limits the field of view of the instruments detectors. A dosimetry module that surveys the radiation environment in cruise to Mars and on orbit around it is another part of the instrument.
This paper describes the mission and the instrument, its measurement principles and technical characteristics. We perform an initial assessment of our sensitivity and time required to achieve the mission goal. The Martian atmosphere is a parameter that needs to be considered in data analysis of a collimated neutron instrument. This factor is described in a section of this paper. Finally, the first data accumulated during cruise to Mars is presented.
The process
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
-
...collider. The
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ϕ
η
intermediate state. Our result on the
e
+
e
-
→
η
η
γ
cross section is consistent with the
e
+
e
-
→
ϕ
η
measurement in the
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
Arrays of silicon nanowires (SiNWs) with characteristic transverse nanowire size of the order of 100 nm were fabricated by metal‐assisted chemical etching of monocrystalline silicon wafers followed ...by thermo‐diffusional doping with boron and studied by means of Raman spectroscopy considering the Fano effect related to the free charge carriers (holes) in SiNWs. The hole concentration of the order of 1020 cm−3 was shown to be achieved for SiNWs annealed at 950–1000°C and the peak intensity of Raman scattering of SiNWs dropped exponentially with the increasing free‐hole concentration. The obtained results can be used for the express diagnostics of the electrical properties of silicon nanostructures for applications in optoelectronics, sensorics, and thermoelectric devices.
Raman spectra of silicon nanowire arrays, which are grown by metal‐assisted chemical etching followed with thermo‐diffusional boron doping at different annealing temperatures, are probed by means of the Raman spectroscopy, considering both the Fano resonance modified spectra and Raman scattering intensity. The obtained results are useful for express‐diagnostics of free charge carriers (FCCs) in doped silicon nanostructures.
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