Radiolysis of the Glycolaldehyde-Na+ Montmorillonite and Glycolaldehyde-Fe3+Montmorillonite Systems in Aqueous Suspension under Gamma Radiation Fields: Implications in Chemical Evolution

J. CRUZ-CASTAÑEDA1, 2, A. L. MELÉNDEZ-LÓPEZ1, 2, S. RAMOS-BERNAL1 AND A. NEGRÓN-MENDOZA1*

1Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, UNAM. Cd. Universitaria, A. P. 70-543, 04510 México, D. F. México

2 Programa de Maestría y Doctorado en Ciencias Químicas, UNAM. Cd. Universitaria, A. P. 70-543, 04510 México, D. F. México

* Email: negron@nucleares.unam.mx

Abstract The 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 glycolaldehydeNa+ -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 nonidentified products. The analysis of these systems was performed by ATRFTIR, UV spectroscopy, liquid chromatography (UHPLC-UV), and HPLC coupled to a mass spectrometry.

DOI: https://doi.org/10.15415/jnp.2017.51013

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/873/1/51013_JNP_Negrón-Mendoza.pdf

Thermoluminescent Characteristics of Li2 B4 O7 Doped with Mn2+ and Eu3+ Ions

P. TREJO-GARCÍA 1, E. CRUZ-ZARAGOZA3 , R. ACEVES2 , J. E. ESPINOSA1 , R. PALOMINO MERINO1*

1 Facultad de Ciencias Físico-Matemáticas, B. Universidad Autónoma de Puebla., Pue., Ciudad Universitaria, Puebla, Pue., México. P.O. Box 1067, C.P. 72001 México.

2 Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-088, 83190 Hermosillo Sonora, México.

3 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70- 543, 04510 Ciudad de México, México

1*Email: palomino@fcfm.buap.mx

Abstract 
Analysis of thermoluminescent properties were made for two samples; Li2 B4 O7 , Li2 B4 O7 :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 Li2 B4 O7 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.

DOI: https://doi.org/10.15415/jnp.2017.51012

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/872/1/51012_JNP_Merino.pdf

Radio-Optically- and Thermally Stimulated Luminescence of Zn(BO2 ) 2 :Tb3+ exposed to Ionizing Radiation

E CRUZ-ZARAGOZA1*, G CEDILLO DEL ROSARIO1,2, M GARCÍA HIPÓLITO2 , J MARCAZZÓ3 , J M HERNÁNDEZ A4 , E CAMARILLO4 AND H MURRIETA S4

1Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. P. 70-543, 04510 Ciudad de México, México

2 Posgrado en Ciencia e Ingeniería de Materiales, Instituto de Investigaciones en Materiales-UNAM, A. P. 70-360, 04510 Ciudad de México, México

3 Instituto de Física Arroyo Seco-CIFICEN, CONICET-UNCPBA, Pinto 399, 7000 Tandil, Argentina

4 Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000 Ciudad de México, México

*Email: ecruz@nucleares.unam.mx

Abstract The optical absorption of zinc tetraborate at different concentrations of the terbium impurity (0, 0.5, 1, 2, 4, 8 mol%) was analyzed. The radioluminescence (RL) emission spectra was obtained after beta irradiation of a 90Sr/90Y source. The RL spectrum showed the characteristics bands of Tb3+ with two main emissions at 489 nm and 546 nm which corresponding to the5 D4 →7 F6 and 5 D4 →7 F5 transitions respectively in this ion. The OSL and TL characteristics have been analyzed. The stimulation blue light (497 nm) of a diode laser at 500 mA was used to bleach the thermoluminescent (TL) signals obtained with 5Gy of 60Co source. The two main glow peaks (79 and 161 °C) are sensitives under 497 nm stimulation, and they were shifted to higher temperature values and faded their TL intensities. Similar behavior of TL glow curves before and after OSL stimulation with blue light was observed when the samples were exposed to 30 Gy gamma dose of 137Cs irradiator. The OSL signal response was linear with the dose range of 1-10 Gy and increased their response up to 200 Gy gamma dose. The OSL shows a bleaching sensitive shallow traps and diminishing the intensity of the TL glow curves remaining a complex traps distribution. The RL, TL and OSL properties were investigated in Zn(BO2 )2 :Tb3+ phosphor.

DOI: https://doi.org/10.15415/jnp.2017.51016

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/876/1/51016_JNP_%20ECruz-Zaragoza.pdf

Radon Exhalation from Industrial Residues as Suitable Additives for Building Materials

H BARROS1 , * G ESPINOSA2 , W RODRIGUEZ1 AND L SAJO-BOHUS1

1 Universidad Simón Bolívar. Apartado 89000, Caracas 1080 A, Venezuela.

2 Instituto de Física, Universidad Nacional Autónoma de México, Coyoacán, México

 *Email: hbarros@usb.ve

Abstract Radon exhalation from phosphogypsum (PG) and red mud (RM) samples are of environmental concern. The study is oriented to evaluate by different nuclear techniques, industrial materials cumulated in sites at Morón (PG) and Puerto Ordaz (RM) in Venezuela. RM samples and industrial by products are assessed for its potential use as additives in building materials regarding its radiological health risk. Radioactive matter concentration in RM is up to 11.6 kBq.kg-1. Radon concentration range for RM dry powder is between DL and 2.5 kBq.m- ³ and for PG is between 105-340 Bq.m- ³. Results indicate that industrial by product before it can be used as additive; require remedial actions to lower the environmental impact. Experimental values are compared with locally available cement, bricks and gypsum building materials.

DOI: https://doi.org/10.15415/jnp.2017.51011

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/871/1/51011_JNP_bannoza.pdf

Radiolysis of Nucleosides: Study of Sedimentary Microenvironment Models for the Protection of Bio-Organic Molecules on Early Earth

E Y AGUILAR-OVANDO1,2* AND A NEGRÓN-MENDOZA1

1 Instituto de Ciencias Nucleares (ICN), Universidad Nacional Autónoma de México (UNAM)

2 Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos (UAEM)

*Email: ellen.aguilar@nucleares.unam.mx

Abstract Nucleic acid bases and their derivatives are important compounds in biological systems. Many efforts have been made to demonstrate the possible prebiotic origin of these molecules, but the abiotic synthesis of these compounds has proved to be very difficult in that conditions. So, if their synthesis actually took place, a study of their stability in prebiotic conditions is quite relevant in chemical evolution studies. In this work, it has been examined and compared the influence of Sodium Montmorillonite on the chemical transformations undergone by two nucleosides (guanosine – purinic– and uridine, –pyrimidinic–) when subjected to conditions simulating the primitive Earth during the period of chemical evolution. The experiments prove the concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) that clays can provide to these specific compounds adsorbed on them. By using X-ray diffraction, UVvis spectrophotometry and HPLC for the analysis, it was found that purinic nucleosides (more than pyrimidinic) are quickly adsorbed on clay at low pH values, and the temperature of mineral desiccation applied after adsorption promotes their decomposition into their corresponding nitrogenous bases. In both, purinic and pyrimidinic, desorption occurs in neutral or slightly basic aqueous solutions, and both are protected by clay. Pyrimidinic nucleosides show more resistance to heat, but less resistance towards ionizing radiation, even when adsorbed in clay.

DOI: https://doi.org/10.15415/jnp.2017.51010

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/870/1/51010_JNP_Aguilar%20-%20Negron.pdf

Application of a CdTe Detector for Measurements of Mammographic X-ray Spectra

J C SANTOS 1*, A TOMAL2 AND P R COSTA1 .

1 Instituto de Física, Universidade de São Paulo, SP, Brazil

2 Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, SP, Brazil

*Email: josilene@usp.br

Abstract 
This work aims to characterize mammographic x-ray beams incident and transmitted by breast phantoms (from 0 to 45 mm) composed from known proportion of glandular and adipose tissue-equivalent materials. This study was performed for mammographic x-ray beams generated by a mammography equipment using different target/filter combinations (Mo/Mo, Mo/Rh and W/Rh). It was studied the modification of spectra shape of the beams transmitted through different thicknesses of these materials. It was also evaluated the penetrability of these transmitted beams by its correlations to the HVL, which were experimentally estimated and derived from the x-ray spectra measured using a spectrometry system with a CdTe detector. The x-ray spectra transmitted by the phantom with higher density presented lower intensity than those transmitted by those with lower density, as expected. The differences between the HVL values derived from the spectra and those estimated using air kerma measurements are lesser than 6% for about 88% of the spectra measured in this work. The expected spectra variations with phantom thickness, revealed by the measured transmitted x-ray spectra, were also confirmed by HVL measurements and agree with the estimated attenuation curves. The motivation of the study was related to the robustness of the spectra as a descriptor of radiation beams and the possibility of using these transmitted spectra for dose assessment related to mammographic procedures. We can conclude that developed method is able to characterize mammographic x-ray beams making it possible the use of this kind of data for dose assessment in mammography.

DOI: https://doi.org/10.15415/jnp.2017.51009

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/869/1/51009_JNP_Josilene%20Santos%20-%20Brasil.pdf

Characterization Of Structures Of Equivalent Tissue With a Pixel Detector

M.C GRADOS LUYANDO* , B. DE CELIS ALONSO, E. MORENO BARBOSA, M.I. MARTÍNEZ HERNÁNDEZ, J.M. HERNÁNDEZ LÓPEZ AND G. TEJEDA MUÑOZ

1 Benemérita Universidad Autónoma de Puebla

*Email: carminagl87@gmail.com

Abstract 
Research using hybrid pixel detectors in medical physics is on the rise. Timepix detectors have arrays of 256 × 256 pixels with a resolution of 55 µm. Here, and by using Timepix counts instead of Hounsfield units, we present a calibration curve of a Timepix detector analog to those used for CT calibration. Experimentation consisted of the characterization of electron density in 10 different kinds of tissue equivalent samples from a CIRS 062M phantom (lung, 3 kinds of bones, fat, breast, muscle, water and air). Radiation of the detector was performed using an orthodontic X-ray machine at 70 KeV and .06 second of tube current with a purpose-built aluminum collimator. Data acquisition was performed at 1 frame per second and taking 3 frames per phantom. We were able to find a curve whose behavior was similar to others already published. This will lead to the verification of the usage of Timepix for identification of different tissues in an organ.

DOI: https://doi.org/10.15415/jnp.2017.51008

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/868/1/51008_JNP_Grados%20-%20Buap.pdf

Analysis and characterization of neutron scattering of a Linear Accelerator (LINAC) on medical applications.

A. LIMA FLORES1 , R. PALOMINO-MERINO1 , E. ESPINOSA1 , V.M. CASTAÑO2 , L. GUZMÁN-GATICA3 AND G. ESPINOSA4

1 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Avenida San Claudio y 18 Sur, Colonia San Manuel, Ciudad Universitaria, Puebla C.P.72570, México

2 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro C.P.76230, México

3 Servicios de Salud del Estado de Puebla, Antiguo Camino a Guadalupe Hidalgo 11350, Puebla C.P. 72490, México

4 Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad Universitaria, México D.F. C.P.04510, México

*Email: jaflores8630@gmail.com

Abstract 

In 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. 

DOI: https://doi.org/10.15415/jnp.2017.51007

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/867/1/51007_JNP_Lima-Flores%20Buap.pdf

Study of H2/N2Mixture Plasma Treatment on the AISI 1045

E. PARDO L.1*, J.G. GONZÁLEZ- RODRÍGUEZ1 , B CAMPILLO2 , F. CASTILLO2 , O. FLORES2 AND H. MARTINEZ2

1 Center of Research in Engineering and Applied Science, FCQeI UAEM., Av. Univ. 1001 Col., Chamilpa 62209, Cuernavaca Mor., Mexico

2 Institute of Physical Sciences, Autonomous National University of Mexico, P.O. Box 48-3, Av. Universidad s/n, Col. Chamilpa 62210, Cuernavaca Mor., Mexico

*Email: esteban.pardo@uaem.mx

Abstract:
 In 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.

DOI: https://doi.org/10.15415/jnp.2017.51006

LINK: http://dspace.chitkara.edu.in/jspui/bitstream/1/866/1/51006_JNP_Pardo%20-%20Fermin.pdf

Study of secondary muons detected within the tunnels of the Cholula pyramid

E. MORENO-BARBOSA1*, J.E. ESPINOSA-ROSALES1 , J. COTZOMI-PALETA1 , B DE CELIS-ALONSO1 , M. CRUZ-SÁNCHEZ2 , E. MERLO-JUÁREZ2 , P. TREJOGARCÍA1 , A. LIMA-FLORES1 , R. PALOMINO-MERINO1

1 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Avenida San Claudio y 18 Sur, Col. San Manuel, Ciudad Universitaria, Puebla, Puebla. C.P. 72570, México.

2 Instituto Nacional de Antropología e Historia , Delegación Puebla, Zona Arqueológica de Cholula, 8 norte núm. 2, colonia centro , San Andrés Cholula, Puebla, C.P. 72760, México

*Email: emoreno@fcfm.buap.mx

Abstract 

The pyramid of Cholula was built at the beginning of 100 B.C. and during of period of 500 years it was finished, had several new constructions, based on the previous constructions. The primarily material of construction is the adobe. Early in 1931 archaeological excavations began with the intention of exploring the interior of the pyramid, excavations were stopped in 1971, and to date no further excavations have been carried out. This work shows the first measurements of muons, particles that are very penetrating, these are generated by primary cosmic rays that was incoming in the atmosphere and these generates a rain of secondary particles, among them the muons. To measure this kind of particles was implemented a detector system, it is formed by a scintillator plastic coupled to a tube photomultiplier; the signals were acquired by mean of an oscilloscope. The detector was collocated near of the center of the pyramid; the location belongs to the maxima concentration in mass over the detector. Graphs of the charge distribution, maximum amplitude and characteristic rise times of the generated pulses in a plastic scintillator are shown, this is scintillator was synthesized in the materials laboratory of the FCFM-BUAP. In addition the optical characterization of the same was realized.

DOI: https://doi.org/10.15415/jnp.2017.51005

LINK:http://dspace.chitkara.edu.in/jspui/bitstream/1/865/1/51005_JNP_Moreno%20-%20Palomino.pdf