Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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Ionizing Radiation, an Instrument in Chemical Evolution Studies: Scope and Perspectives
Get PDFThe study of synthesis and stability of molecules in different environments it’s been part of chemistry evolution and origin of life studies for more than 70 years. Various kinds of ionizing radiation have been analyzed as possible sources of energy for the transformations undergone by the first organic molecules. Now experimental and computational simulation approaches continue with different groups of organic molecules, in search for more information that help us to understand and reconstruct somehow the mechanisms that toke place on early Earth and space. In that line, this paper presents first approach of keto acids stability to ionizing radiation, an interesting group of molecules involved in the Krebs cycle and glycolysis. Preliminary results obtained by HPLC/UV analysis of irradiating aqueous solutions of 5 keto acids ranging from 3 to 6 carbons with a 60Co gamma ray source, using doses up to 53 kGy, show different stabilities and a general tendency of shifting the keto-enol equilibrium to the enol tautomer before decomposition
Gamma Radiation Doses Effects on Mechanical Properties and Microwave Absorption Capacity of Rubber Doped Concrete
Get PDFThe main raw material for the construction industry is concrete; whose fundamental components are the fine and coarse aggregates, water and cement. For the obtaining of these materials are necessary activities that generate environmental deterioration, since the aggregates are extracted from quarries or river banks and for each ton made of cement is emitted into the atmosphere a great lot of carbon dioxide. In this way, the present work is developed with the purpose of contributing to the research that can help the conservation of basic natural resources through the use of waste polymers such as waste tire rubber, in the production of concrete, hoping to reduce its harmful environmental impact. This work focuses on the one hand, in the study of the effects of the incorporation to the concrete, of different proportions of scratched rubber coming from waste tires, on its mechanical properties and on its capacity for microwaves absorption. On the other hand, it is also studied the effect of aging by applying different doses of gamma radiation on the before mentioned properties, seeking with this the possibility that it can be used in the construction industry either as structural material or as a coating. Replacements were made between 5% and 25% of rubber in order to do not significantly affecting the mechanical properties of the concrete. The results of the mechanical and microwave tests performed on the different samples with different gamma radiation doses were compared and it was found that open the possibility of research with great benefits such as the use of waste tires in the designing of concrete mixtures and the improvement of its properties. It is considered important to point out the economic benefit in the context of sustainable development, which involves solving the problem of environmental pollution caused by waste tires, to achieve the welfare of the population by improving their quality of life
In vitro Study of the Survival, Reproduction and Morphology of Daphnia pulicaria irradiated with a Low Energy Laser
Get PDFDaphnia is a genus of crustaceans that is representative of freshwater communities. The species exhibit a high sensitivity to a wide range of toxic compounds so that they have been used internationally as biomonitors in toxicity tests to evaluate ecosystem conditions such as water quality. It is also a model genus in genetics, epigenetics and reproductive ecology. In this work, we used Daphnia pulicaria as a model to measure the effects of low-energy laser irradiation on survival, reproduction, and morphology variables of parental organisms and their offspring. We used (1) a single clone line of organisms to eliminate interindividual genetic variability; (2) individuals from more than 50 generations after the clone line was established, and offspring from the third brood onwards to dissipate maternal and epigenetic effects, and (3) neonates, those individuals of the species that have less than 48 hours of life, because they are the most sensitive stage to optical stimuli. We analyzed number of deaths, longevity, age at first reproduction, number of offspring per week, number of total offspring during all their life cycle, body size, size of the antennules, and length of the apical spine of the 4th and 5th brood of the irradiated individuals, who were exposed to a blue laser stimulus of 405 nm for 25 minutes with a power of 40 mW at a distance of 50 cm, compared to those of the control (non-irradiated) group
The Three-Body Structure of 2n and 2p Halo Nuclei
Get PDFA three-cluster model developed for ternary fission studies has been applied for the first time to study the three-body structure of 2n and 2p halo nuclei. For the experimentally known 2n, 2p halo nuclei, all possible ternary fragmentation potential energy surface (PES) is calculated. The two-body breakup reported earlier, clearly indicated a strong minimum in the PES corresponding to 1n/1p and/or 2n/2p cluster plus core configuration. However, the present calculations of PES reveal that, the three- body breakup does not result always with 2n and/or 2p as a cluster. A 1n and/or 1p cluster along with the core is initially formed, and then the core loses one nucleon to make either a 2n plus core or 2p plus core structure. The results are substantiated with the calculations of preformation probability calculated within quantum mechanical fragmentation theory
Analysis of the Energy Deposit in the Air by Radiation of Alpha Particles Emitted by the Water of a Spring Through the Geant4 Software
Get PDFThis work presents the development of an analysis of the potential radiological risk generated by alpha particles emitted by radon-222, content in a spring water, for the population that usually swims in the place and for the people who live near this spring. This spring is located in the state of Puebla. Several measurements in the water of this place by researchers from IF-UNAM showed that it contains an average radon concentration level of 70 Bq/m3. To evaluate this radiological risk, it has been developed a computational simulation to know the area and the height where the alpha particles deposit their energy to the medium, as well as the amount of energy that they transfer. This simulation was developed in the Geant4 scientific software and the calculations were executed in the supercomputer of the Laboratorio Nacional de Supercomputo del Sureste de Mexico of the BUAP. The results show that the energy deposit occurs within the superficial limits of the spring, between 7 and 8 meters high. This deposited is not only by the alpha particles, but also by the secondary particles that are generated by the interaction of alpha particles with the environment. Based on these results, it is confirmed that there is no radiological risk by energy deposit by alpha particles for the people
In silicoAnalysis of the Structural Properties of PSMA and its Energetic Relationship with Zn as Cofactor
Get PDFThe prostate-specific membrane antigen (PSMA) is a 100 kDa type II transmembrane glycoprotein with enzymatic activity similar to the family of zinc-dependent exopeptidases. This protein is of great medical and pharmacological interest as overexpression in prostate cells is related to the progression of prostate cancer; therefore, it represents an important target for the design of radiopharmaceuticals. The presence of two Zn2+ ions in the active site is crucial to the enzymatic activity and the design of high-affinity inhibitors. The amino acid residues coordinating these ions are highly conserved in PSMA orthologs from plants to mammals, and site-mutagenesis assays of these residues show a loss of enzymatic function or reduction of the kinetic parameters. In the present work, we performed molecular dynamics simulation of PSMA with the purpose of characterizing it energetically and structurally. We elucidated the differences of PSMA with its two Zn+2 ions as cofactors and without them in the free energy profile, and in four structural parameters: root mean square deviations and root mean square fluctuations by atom and amino acid residue, radius of gyration, and solvent accessible surface area
Spontaneous CP Violation Jarlskog Invariant in SM ⊗ S3
Get PDFIn our days, CP (Charge Parity) violation in the Standar Model of fundamental interactions still remains as an open problem. It is well known that explicit CP violation may be included by impossing complex Yukawa couplings in the Yukawa sector or complex Higgs couplings in exttended Higgs sectors with more than one Higgs field. It is desirable to have a fundamental CP violation theory, in that sence, we analyse the diferent secenarios for Spontaneous CP violation in an exteded Higgs model with three Higgs fields and a discrete flavour permutational symmetry S3. Spontaneous CP violation effects contribute to the Higgs mass matrix, as well as, up and down quark mass matrices. This complex quark mass matrices allow us to study the conditions for a non-vanishing Jarlskog invariant J which provides a necessary and sufficient contribution for a spontaneous CPV coming from SM ⊗ S
Improvements to the X-ray Spectrometer at the Aerosol Laboratory, Instituto de Física, UNAM
Get PDFDue to the demands of better (accurate and precise) analytical results using X-ray Fluorescence (XRF) at the Aerosol Laboratory, Instituto de Física, UNAM, it was necessary to carry out improvements in instrumentation and analytical procedures in the x-ray spectrometer located in this facility. A new turbomolecular vacuum system was installed, which allows reaching the working pressure in a shorter time. Characteristic x-rays are registered with a Silicon Drift Detector, or SDD, (8 mm thick Be window, 140 eV at 5.9 keV resolution), working directly in a high-vacuum, permitting the detection of x-rays with energies as low as 1 keV (Na Ka) and higher counting rates than in the past. Due to the interference produced by the Rh L x-rays emitted by the tube normally used for atmospheric and food analysis with Cl K x-rays, another tube with a W anode was mounted in the spectrometer to avoid this interference, with the possibility to select operation with any of these tubes. Examples of applications in atmospheric aerosols and other samples are presented, to demonstrate the enhanced function of the spectrometer. Other future modifications are also explained
Mass Attenuation Coefficient Measurements of Some Nanocarbon Allotropes: A New Hope for Better Low Cost Less-Cumbersome Radiation Shielding Over A Wide Energy Range
Get PDFThe mass attenuation coefficients of graphene, MWNTs and, SWNTs have been measured for gamma energy range 356 to 1332 keV from the radioactive sources 60Co, 133Ba and 137Cs using a well calibrated gamma ray spectrometer consisting of a 3 ́ ́x 3 ́ ́ NaI(Tl) scintillation detector coupled to a PC based 8K nuclear Multi Channel Analyser (MCA). In an interesting way results showed that MWNTs had the highest values of mass attenuation coefficients indicating their potential use as the best shielding material
Radon in Workplaces the Urgent Need of New Measurements and Devices
Get PDFThe existing passive radon monitors, their relative calibration facilities together with the past intercomparison exercises have been mission-oriented towards radon measurements in dwellings. These monitors have been successfully applied throughout the world for radon measurements in homes, characterized by temperatures in the range from 20 to 25°C and a relative humidity less than 50 R.H. A multitude of different problems may arise when these passive monitors are used in environment other than homes, such as in soil and in workplaces, where large humidity up to 100 RH and temperatures anywhere from 0°C to 40°C may be encountered. Under severe environmental conditions, different measurement errors may occur which have remained concealed to date. These errors may be caused by a drastic change of both the radon diffusivity through the and for the monitor housing respectively. permeation membranes or the radon absorption by the plastics, used for the track detector. For the compliance to the assessment of the occupational exposures, it is necessary to eliminate all the possible sources of errors, which may be conducive to litigation. Another important shortcoming of the existing passive monitors is the difficult to turn them on/off daily, as required for radon measurements in workplaces. Finally, most of the problems, listed above, can be solved by the exploitation of a new generation of passive monitors, known as Rn film-badges. These monitors are similar and often identical to neutron film-badges, which have proved to be very successful throughout the world for the personnel neutron dosimetry. In particular, the present paper will describe the unique characteristics of these radon film badges, such as compactness, fast time response, any desired response sensitivity, simplicity in turning them on and off, etc