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Journal of Geoscience and Environment Protection 2022年第7期10卷 257-265页

作者： Fridda Concepción Fuentes Gama juan manuel navarrete tejero Alejandro Ramírez Chávez Miguel Ángel Zúñiga Pérez Department of Inorganic and Nuclear Chemistry Faculty of Chemistry National Autonomous University of Mexico Mexico City Mexico

Several previous papers have been published about radioactive contamination in Mexican soil, marine sediments and foodstuffs. Ever since, results have been according to expectation, mainly consisting of natural isotopes in small concentration. Continuous research leads with the surprising finding of fission product 137Cs (t1/2 = 30 years) in strawberries produced in different states, about 2000 km away from each other. Never before, such contaminant has been observed in foodstuffs, produced in this country. The aim of this work is to report the presence of 137Cs in Mexican strawberries and compare the activity of such contaminant with the natural radioactivity of 40K (t1/2 = 1.28 × 109 years), through gamma spectrometry. Eventually, the specific activity of 137Cs observed in samples FM4, FM5 and FBC is respectively 0.7, 0.8 and 0.3 Bq/kg. The limits established in CODEX-STAN-193-1995 for 137Cs are 1000 Bq/kg, so all samples meet the recommendation. It’s presence now in vegetables result with enough interest to be known and considered in the near future to measure the possible effect that radioactive contamination could reach after nearly 80 years from second world war, where no nuclear test has been performed, nuclear accident occurred, neither nuclear weapon has ever been used.

关键词： Radioactive Contamination

Consolidation of Ancient Raw Materials Using a Reversible, Elastic, Soft Polymer

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Advances in Materials Physics and Chemistry 2012年第1期2卷 37-42页

作者： juan manuel navarrete Gustavo Leonardo Martínez Faculty of Chemistry Inorganic and Nuclear Chemistry Department National University of Mexico Mexico City Mexico National Coordination to Restore the Cultural Inheritance National Institute of Anthropology and History Mexico City Mexico

Aging of ancient raw materials usually finish with disintegration, which starts on surface of walls to progress toward the inside mass of a huge variety of mineral compounds. This is particularly harmful when antique buildings keep mural paintings, which suffers destruction before the wall itself. Same case appears on sculptures and monuments, whose surfaces are often attacked by living organisms which start a deterioration process previous to complete disintegration. The main factor to produce these unwanted effects is humidity, either rain for materials exposed to open air, or underground humidity going up by capillarity of minerals, in this case represented by porosity of associated salts forming the material. This paper describes a method to measure easily the relative porosity of diverse raw materials at laboratory level, by using a radioactive labeled solution, and also a procedure to reduce their porosity of those minerals. The efficiency of this procedure is measured in the same way, and so the results obtained at laboratory level have encouraged its use at real scale, where it has been quite successful for a number of materials in a limited span of five years.

关键词： Consolidation Preservation Humidity Ancient Materials

Assessment of Present and Future Radioactive Contamination at Global Scale

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Journal of Chemistry and Chemical Engineering 2012年第11期6卷 1010-1015页

作者： juan manuel navarrete Miguel Angel ZUNiga Guillermo Espinosa Jose Ignacio Golzarri Faculty of Chemistry National University of Mexico Mexico City 04510 Mexico Institute of Physics National University of Mexico Mexico City 04510 Mexico

As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has been accumulated mainly in marine sediments, because sea is about 80% of planet surface, and solid fission products released by nuclear explosions are transported by wind first and then by rain to liquid and solid portions on earth, while gaseous fission products are diffused in the atmosphere. In this way, heavy, high yielding fission products, such as 137Cs, get marine sediments, where they are found mixed with heavy radioactive natural elements such as U, Th and their also radioactive decay products. But since alkaline are so abundant on earth, it is also found natural radioactive isotope 4~K, 0.0118% of isotopes forming K element, with half life 1.28 ~ l09, in the time range of planet age and elements origin. So, one easy way to assess both the importance and evaluation of radioactive contamination at global scale should be to establish a RCF （radioactive contamination factor） as a percentage of 137Cs contaminant radioactivity in marine sediments, compared to 4~K natural radioactivity present from the very beginning of earth, both expressed as Bq per gram of sediment. In the frame of these rather general considerations, a research project has started in Mexico whose varied purposes are： to characterize sea regions in both vast littorals in the country, by its natural 4~K radioactivity present in sea salts, as well as to determine if 137Cs traces produced by recent radioactive contamination have reached their coasts. Also, to assess the 137Cs traces already present in marine sediments as a result of more than two thousand nuclear test explosions performed till now, rather than contamination produced by four main accidents in nuclear reactors during the last 60 years. It is proposed a radioactive contamination factor obtained from samples taken up in

关键词： Contaminant natural radioactivity relation coefficient.

Isobars Separation (137Cs-137mBa-137Ba) from Marine Sediments, in Order to Evaluate Directly Their Radioactive Contamination by Mass Spectrometry

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World Journal of Nuclear Science and Technology 2020年第1期10卷 32-38页

作者： Karla Fernández juan manuel navarrete Miguel Angel Zúñ iga Ernesto Hernández Department of Inorganic and Nuclear Chemistry Faculty of ChemistryNational Autonomous University of MexicoMexico CityMexico

Marine sediments contamination by fission product 137Cs-137mBa is a fact since the period 1945-65, when plus than two thousand atomic explosion tests were performed mainly in the southern seas, earth region with minor population density. However, marine flows have produced dissemination of this radioactive pair through the sea bottom all over the world, at different levels, because the sea movement and natural decaying of radioactive pair: parent 137Cs (t1/2 = 30.17 years) and daughter 137mBa (t1/2 = 2.55 minutes). Radioactive detection of these contaminants, compared as percentage with that of natural 40K (t1/2 = 1.28 × 109 years, 0.0118% of elementary K) leads to radiation contamination factor (RCF), as one possible unit to measure the radioactive contamination intensity in different regions, as well to determine if there is some other possible source of this contaminant, for example water cooling from power nuclear reactors when it is discharged at sea. However, radioactive detection always implies an unavoidable statistical variation, which makes more difficult to appreciate the changes as function of time and region. But at beginning of this century, mass spectrometry has got impressive advances, which makes it much more precise and sensible than radioactive detection [1]. This paper attempts to measure with other units the radioactive contamination: 137Cs atoms number per gram of sample, instead radioactivity, which could be more direct and with minor standard deviation that radioactive detection, solving at same time the isobars separation: 137Cs versus 137mBa plus elementary 137Ba (11.23% of Ba element).

关键词： Isobars Separation 137Cs-137mBa-137Ba

Oral administration of the cannabigerol derivative VCE-003.2 promotes subventricular zone neurogenesis and protects against mutant huntingtin-induced neurodegeneration

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Translational Neurodegeneration 2019年第1期8卷 111-125页

作者： José Aguareles juan Paraíso-Luna Belén Palomares Raquel Bajo-Grañeras Carmen navarrete Andrea Ruiz-Calvo Daniel García-Rincón Elena García-Taboada manuel Guzmán Eduardo Muñoz Ismael Galve-Roperh Instituto Ramón y Cajal de Investigación Sanitaria(IRYCIS) Ctra.Colmenar Viejokm9100 MadridSpain Departamento de Bioquímica y Biología Molecular and Instituto Universitario de Investigación Neuroquímica Universidad ComplutenseMadridSpain Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas(CIBERNED) MadridSpain Instituto Maimónides de Investigación Biomédica de Córdoba(IMIBIC) CórdobaSpain Departamento de Biología Celular Fisiología e InmunologíaUniversidad de CórdobaCórdobaSpain Hospital Universitario Reina Sofía CórdobaSpain Emerald Health Pharmaceuticals San DiegoUSA

Background:The administration of certain cannabinoids provides neuroprotection in models of neurodegenerative diseases by acting through various cellular and molecular *** cannabinoid actions in the nervous system are mediated by CB1 receptors,which can elicit psychotropic effects,but other targets devoid of psychotropic activity,including CB2 and nuclear PPARγreceptors,can also be the target of specific ***:We investigated the pro-neurogenic potential of the synthetic cannabigerol derivative,VCE-003.2,in striatal neurodegeneration by using adeno-associated viral expression of mutant huntingtin in vivo and mouse embryonic stem cell differentiation in ***:Oral administration of VCE-003.2 protected striatal medium spiny neurons from mutant huntingtin-induced damage,attenuated neuroinflammation and improved motor ***-003.2 bioavailability was characterized and the potential undesired side effects were evaluated by analyzing hepatotoxicity after chronic ***-003.2 promoted subventricular zone progenitor mobilization,increased doublecortin-positive migrating neuroblasts towards the injured area,and enhanced effective ***,we demonstrated the proneurogenic activity of VCE-003.2 in embryonic stem ***-003.2 was able to increase neuroblast formation and striatal-like CTIP2-mediated ***:The cannabigerol derivative VCE-003.2 improves subventricular zone-derived neurogenesis in response to mutant huntingtin-induced neurodegeneration,and is neuroprotective by oral administration.

关键词： Cannabinoid Huntingtin Neurodegeneration Neurogenesis PPAR

Potassium Concentration by Natural ^40K-^40Ar Y Rays Detection in Four Basic Diet Products （Milk, Eggs, Wheat and Corn）

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Journal of Life Sciences 2011年第8期5卷 614-617页

作者： juan manuel navarrete Trinidad Martinez Luis Cabrera Pilar Lizarraga Miguel Angel Zuniga Michelle Camacho Faculty of Chemistry Building D National University of Mexico CU Mexico City ZC 04510 Mexico

The purpose of this paper is double： first to measure the natural radioactivity in any food by detecting the omnipresent radiation of ^40K, and then to use this date to obtain the concentration of the important mineral nutrient K, by dividing the specific activity of the sample （Bq/g） by the specific activity of elementary K （31.19 Bq/g）. The method implies the γ rays detection emitted by natural ^40K-^40Ar present in foodstuff, by using a 3 × 3＂ low background NaI （TI） scintillation detector coupled to a PC charged with the Maestro Program. When this detection system is calibrated in order to determine its efficiency for 1461 KeV γrays emitted during ^40K-^40Ar decaying, it is possible to measure easily and with enough precision the specific activity due to natural ^40K present in any foodstuff. Once this figure is divided by the constant value of ^40K specific activity of elementary K, the concentration of this element in the foodstuff sample is established. This paper describes the procedure and shows the results obtained with four basic diet products： milk （powdered, light and cream）, eggs （yellow and white）, wheat （whole and refined flour） and corn （whole and cornstarch flour）. The possible application of this study seems to be to establish the necessary threshold to evaluate the importance of any possible radioactive contamination, as well as to measure the concentration of the mineral nutrient K in foodstuff, by means of an easy, practicable method. Also, it might be useful as an experiment for teaching purposes.

关键词： Radioactivity nourishment potassium concentration ^40K-^40Ar Y rays.

Technology for the Production of Sorghum for Grain in the Vertisols of Campeche, Mexico

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Agricultural Sciences 2021年第6期12卷 666-683页

作者： juan Medina-Méndez Jesús manuel Soto-Rocha Mirna Hernández-Pérez Joaquín Gómez-tejero Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias Campo Experimental Edzná Campeche México

This research was conducted in the state of Campeche, Mexico, between 2017 and 2018. On the one hand, the sorghum yield was explored in plots with Vertisol-type soils, which were supplied with rainwater. This had the purpose of knowing the results obtained by the producers in the area. On the other hand, an experiment was established with three factors: the genetic material of sorghum, planting density and fertilization. Finally, different varieties of soybeans and sorghum hybrids were also tested in large plots, to identify those that are best adapted to crop rotation. In the farmers’ plots, the grain yield was between 4377 and 5543 kg∙ha−1. The planting density was from 142,667 to 197,334 plants per hectare, which indicated that, for each unit that increased the planting density, the yield increased by 37.5 grams. The experiment with three factors indicated that the best planting density was 300 thousand plants per hectare, with a grain yield of 5176 kg∙ha−1;and the best hybrids were DKS-32 and SYN5515, with grain yields of 5794 and 3791 kg∙ha−1, respectively;likewise, the best dose of fertilizer was between 150 and 200 kg∙ha−1 of diammonium phosphate, with a grain yield of 4527 - 4562 kg∙ha−1. In relation to crop rotation, the varieties that stood out for their yield were Huasteca 300 and Vernal, in the case of soybeans;and the hybrids DKS-32 and SYN5515, in sorghum. Soybeans suffered greatly in their early stages of development from the excessive

关键词： Vertisols Tropics Grains Crop Rotations

Productivity of White and Yellow Grain Corns in Campeche, México

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Agricultural Sciences 2019年第9期10卷 1255-1269页

作者： juan Medina-Méndez Jesús manuel Soto-Rocha Antonio Villalobos-González Víctor Hugo Volke-Haller Joaquín Gómez-tejero Campo Experimental Edzná Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias Campeche México Postgrado en Edafología Colegio de Postgraduados Montecillo México

The present work took place in the central and northern regions of the state of Campeche, Mexico. The grain yield was evaluated in a total of 46 materials, comprising 30 of white grain and 16 of yellow grain. The crop was supplied to a greater extent with rainwater from the months of July to November. The sowing was in trials designed to evaluate grain yield and technology validation lots established for demonstration purposes. To integrate a genetic material into this study, it was a fundamental requirement that it had at least four evaluations considering different locations or years. As a result of the above, it was determined that there are 27 hybrids of white grain and 14 of yellow grain, which constitute options for the producer with which it is possible to obtain yields of 4.1 to 6.0 t⋅ha−1 and that can make corn a profitable crop under the current conditions of technology application. Of the white grain hybrids, the group formed by SB-309, DK-395, DK-393, DAS-2382, SP-500, DK-390, P4082W, 9209W, P3966W, SORENTO, JC-25, LUCINO, and 9401W was considered as the high productivity stratum, whose average yield is 5.1 to 5.9 t⋅ha−1. Similarly, in the yellow grain hybrids, the group formed 9107Y, SP-525A, 2B688, DK-7500, P4226A, IMPACT and DK-7088, was considered as the high productivity stratum, whose average yield fluctuated from 5.0 to 5.9 t⋅ha−1.

关键词： White and Yellow Maize Tropics Arable Soils