Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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Radiolysis of the Glycolaldehyde-Na+Montmor- illonite and Glycolaldehyde-Fe3+Montmorillonite Systems in Aqueous Suspension under Gamma Radiation Fields: Implications in Chemical Evolution
Get PDFThe stability and reactivity of organic molecules with biological and pre-biological significance in primitive conditions are of paramount importance in chemical evolution studies. Sugars are an essential component in biological systems for the different roles that they play in living beings. The objective of the present work is to study the gamma radiolysis of aqueous solutions of glycolaldehyde, the simplest sugar and aqueous suspensions of glycolaldehyde-Na+-montmorillonite and glycolaldehyde-Fe3+Montmorillonite. Our results indicate that the radiolysis of the aqueous solutions of glycolaldehyde (0.03M), oxygen free, mainly produce the linear dimer known as eritriol (122 g/mol) and a sugar-like compound with six carbon atoms (180 g/mol). The experiments with the clay suspensions show that clays can adsorb glycolaldehyde and protect it from gamma irradiation. Additionally, it was observed that depending on the cation present in the clay, the percentage and the product (monomer or cyclic dimer) adsorption was different. In the case of Fe3+ Montmorillonite, this clay catalyzed the decomposition of glycolaldehyde, forming small amounts non-identified products. The analysis of these systems was performed by ATR-FTIR, UV spectroscopy, liquid chromatography (UHPLC-UV), and HPLC coupled to a mass spectrometry
Binary Fission fragmentation of 184 466,476X
Get PDFBased on the statistical theory of fission, we discuss here the binary fission fragmentation of these giant nuclear systems formed in low energy U+U collisions. Here, the mass and charge distribution of fragments from the binary fission of thesesystems are studied at T= 1 and 2 MeV. From our results at T= 1 MeV, fragments in the near-asymmetric and near-symmetric regions pronounce higher yield values. However, at T= 2 MeV, our results are grossly different. Furthermore, the binary fragmentation with the largest yield consists of at least one closed shell nucleus. Different possible binary fission modes are presented to look for U+Ugiant nuclear systems
Study of H2/N2Mixture Plasma Treatment on the AISI 1045
Get PDFIn the present work, we analyzed the effect of the plasma treatment of 80% H2/20% N2 mixture plasma over the AISI 1045 steel. To produce the plasma, an AC discharge of 0.1 A at 350 V was produced at a total pressure of 3.0 Torr. The mixture plasma was analyzed using optical emission spectroscopy (OES), in the wavelength range of 200 to 1100 nm. The principal species observed in the plasma were NH, N2, N2+, H2, and Hα. The electron temperature and ion density have been measured using a double Langmuir probe. The samples of steel were treated by plasma at different discharge times, between 3 and 12 h, at the same pressure and AC parameters (0.1 A and 350 V). The treated samples were characterized using X-ray analysis, finding the phases gamma and epsilon of iron nitride. The thickness of the nitrided layers was measured using a scanning electron microscope (SEM). From the images obtained, it is possible to appreciate the interphase between the nitrided layer and the steel matrix. The relationship between the morphology of the surface of nitrided steel and the wetting was analyzed by measuring the contact angle between the surface and a drop of 5 μL of distilled water. The contact angle of the drop increased with the increase of plasma treatment time. The control sample without treatment presented a smaller angle, and after the treatment the surfaces of the steel became hydrophobic. This may be related to the morphology change of the steel surface produced by plasma treatment
Analysis and characterization of neutron scattering of a Linear Accelerator (LINAC) on medical applications.
Get PDFIn several theoretical and experimental studies, the topic of the undesirable generation of photoneutrons in rooms where a linear accelerator (LINAC) operates has been discussed. When energies above 10 MeV are used to produce X-rays and give radiotherapy treatment to patients resulting in additional radiation to patients. Accordingly, an analysis and characterization of the neutron scattering distribution on different zones in a treatment room contributes to evaluate the radiological health risk to patients, technical and other workers involved in treatment. For the evaluation, a device developed at the PAD-IFUNAM formed by a CR-39 detector enclosed by two 3mm thick acrylic plates was employed. To avoid environmental contamination, the CR-39 and the acrylics plates are enclosed in a round plastic box. Sixteen of these devices were settled in different places inside the treatment room, where a linear accelerator is used. The results show a significant concentration of neutron scattering in areas near the head of irradiation. The recommendation will be to evaluate the neutron scattering concentration in all rooms that’s operates a LINAC in order to verify the radiological health risk and to mitigate the neutron scattering when concentration levels are to high like those in our case, in order to avoid unnecessary exposition to patients and personnel in general
Thermoluminescent Characteristics of Li2B4O7 Doped with Mn2+ and Eu3+ Ions
Get PDFAnalysis of thermoluminescent properties were made for two samples; Li2B4O7, Li2B4O7:Mn2+:Eu3+. These samples were prepared by melt quenching method. The glow curves of the samples show two broad peaks at 160º C and 245 ºC, and a high peak at 130ºC for Li2B4O7 doped. The response of the materials were analyzed according to the doses (0.2-80 Gy), fading (0-72 hours) and reproducibility of the experiment (10 times). To determine how the glow curve is formed, thermal bleaching for a dose of 5 Gy were made from room temperature to 300º C. Besides, X-ray diffraction patterns were recorded to identify the structure and grain size of the samples
Determination of Cu, Zn, Mn & Fe Metals in Soil Employing the EDXRF & FAAS Techniques and Comparative Study of Results
Get PDFTwo analytical spectroscopic techniques viz. EDXRF and FAAS were employed in analyzing the four heavy metals i.e. Cu, Zn, Mn and Fe in 24 soil samples. The heavy metals in understudy soil were found to have very low to high concentration range and so both techniques were compared for a broader range of concentrations. Two methods, open vessel digestion and microwave oven digestion, were used to prepare the liquid samples for FAAS analysis. The results of both of the EDXRF and FAAS techniques were found comparable when high concentration element Fe was determined. However, for the low concentration values, the results were dissimilar. Some statistical methods like regression and Levene’s test are used to compare the results of both the techniques
Sperm Hyperactivation and Capacitation Induced By Light Stimuli in Cryopreserved Semen
Get PDFIn mammals, such as rabbits, there are some factors involved in possible fertilization, from complex changes in the membrane of the sperm to obstruction or non-existent of vas deferens, which creates problems in the number and quality of sperm. In this work, we report the effects of rabbit sperm motility and capacitation of cryopreserved semen samples under light stimuli. The sperm velocities were correlated with the percentage of capacitated and non-capacitated sperm seen with a fluorescent dye. Consequently, we analyzed the specific correlations between irradiation times, supplied energy, and fertility parameters.
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Multiphoton Ionization of Uracil at 355 nm
Get PDFWe present the experimental results from ionization and dissociation by multiphoton absorption (MPI) of uracil and a mixture of uracil with Ar using a Reflectron time of flight spectrometer along with radiation from 355 nm at pulsed Nd:YAG laser . We focus on the light ions production. The MPI mass spectra show that the presence and intensity of the resulting ions depend on the density power of the laser. The resulting ions in the mass spectra are identified and found similar behavior in the case of H+ and C+ as when multiple charged ions are used. Different results were found in contrast with those, recently reported, when electrons or photons of other wavelength were used. The number of 355nm absorbed photons was calculated accordingly to Keldysh theory and similar results were fond using pure uracil or uracil-Ar mixture. Our results are compared with those obtained in other laboratories under different experimental conditions, some of them show only partial agreement and differences are discussed
Understanding the Basics of Final Unification With Three Gravitational Constants Associated With Nuclear, Electromagnetic and Gravitational Interactions
Get PDFEven though ‘String theory’ models and “quantum gravity’ models [1, 2, 3] are having a strong mathematical back ground and sound physical basis, they are failing in implementing the Newtonian gravitational constant [4] in atomic and nuclear physics and thus seem to fail in developing a ‘workable’ model of final unification. It clearly indicates our lack of understanding and uncertain assumptions on which our current physics is being built up. The main issue is: to understand the basics of final unification from hidden, unknown and un-identified physics! Based on the old and ignored scientific assumption put forward by Nobel laureate Abdus Salam, we developed and compiled many interesting semi empirical relations assumed to be connected with nuclear physics, atomic physics and astrophysics [5, 6]. Based on ‘workability’, we appeal the readers to go through
Implementation of a Low Cost For Internal Dosimetry Radiological Survey of Ionization Radiation Exposed Workers In Nuclear Medicine Services
Get PDFBecause the nature of the routine activities carried on in nuclear medicine services, where several not sealed radioactive sources are used, the occupational personal exposed to ionization radiation (POE) is exposed to both, internal and external radioactive contamination and direct radiation also. The most important radioisotope from the point of view of radiological risk in such Nuclear Medicine Services (NMS) is the 131I. The Mexican official regulatory organization in radiological and nuclear safety: Comisión de Seguridad Nuclear y Salvaguardias (CNSNS) specify, as a requirement in the operation license of Nuclear Medicine Services the mandatory of internal and external dosimetry survey of POE. The external dosimetry survey is normally carried out but the internal dosimetry survey is not easy to do, because internal dosimetry systems are too expensive and in Mexico there are only three organizations (CFE-CLV, ININ, CNSNS) where there are these systems but they aren ́t easily available for the Nuclear Medicine Services. Because that before fact, we propose a single, and low cost system (SLCS) to survey the internal dosimetry of POE. This system is based in a scintillation NaI(Tl) 2x2 detector and a common radiation monitor tipically used in the routine radiation and contamination measures, with a minimal infrastructure investment. This system is numerical calibrated with Montecarlo method, and compared with an well established commercial System being a good function corresponding. This system is easy to implementing in any nuclear medicine to complain the requirement of operation license in the internal dosimetry POE survey