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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

The Application of the Generalized Finite Difference Method (GFDM) for Modelling Geophysical Test

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Journal of Geoscience and Environment Protection 2019年第4期7卷 1-17页

作者： Angel Muelas Eduardo Salete juan José Benito Francisco Urena Luis Gavete miguel Urena UNED ETS Ingenieros IndustrialesC/Juan del RosalMadridSpain UCLM IMACICiudad RealSpain UPM ETSIMMadridSpain

The possibility of using a nodal method allowing irregular distribution of nodes in a natural way is one of the main advantages of the generalized finite difference method (GFDM) with regard to the classical finite difference method. Moreover, this feature has made it one of the most-promising meshless methods because it also allows us to reduce the time-consuming task of mesh generation and the numerical solution of integrals. This characteristic allows us to shape geological features easily whilst maintaining accuracy in the results, which can be a source of great interest when dealing with this kind of problems. Two widespread geophysical investigation methods in civil engineering are the cross-hole method and the seismic refraction method. This paper shows the use of the GFDM to model the aforementioned geophysical investigation tests showing precision in the obtained results when comparing them with experimental data.

关键词： Meshless Methods Generalized Finite Difference Method Geophysics

Structure of Ligand-Bound Intermediates of Crop ABA Receptors Highlights PP2C as Necessary ABA Co-receptor

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Molecular Plant 2017年第9期10卷 1250-1253页

作者： María Moreno-Alvero Cristina Yunta miguel Gonzalez-Guzman Jorge Lozano-Juste juan Luis Benavente Vicent Arbona Margarita Menéndez Martin Martinez-Ripoll Lourdes Infantes Aurelio Gomez-Cadenas Pedro L. Rodriguez Armando Albert Instituto de Química Física Rocasolano Consejo Superior de Investigaciones Científicas 28006 Madrid Spain Instituto de Biología Molecular y Celular de Plantas Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia 46022 Valencia Spain Biotecnologia Departament Ciències Agràries i del Medi Natural Universitat Jaume I 12071 Castelló de la Plana Spain

Dear Editor Abscisic acid （ABA） is the main phytohormone involved in adaptive crop responses to drought. ABA signaling relies on the family of pyrabactin resistance 1/PYRl-like/regulatory components of ABA receptors （PYR/PYL/RCAR）, which upon ABA binding form high-affinity ternary complexes with clade A protein phosphatases type 2C （PP2Cs） and inhibit them （Cutler et al., 2010）. This results in the activation of an SnRK2-dependent phosphorylation cascade affecting a high number of targets in the plant cells, regulating stomatal aper- ture and the expression of stress-responsive genes （Cutler et al., 2010）.

关键词： Structure of Ligand-Bound Intermediates Crop ABA Receptors Highlights PP2C

Bench-top aqueous two-phase extraction of isolated individual single-walled carbon nanotubes

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Nano Research 2015年第5期8卷 1755-1769页

作者： Navaneetha K. Subbaiyan A. Nicholas G. Parra-Vasquezt Sofie Cambre miguel A. Santiago Cordoba Sibel Ebru Yalcin Christopher E. Hamilton Nathan H. Mack Jeffrey L. Blackburn Stephen K. Doorn juan G. Duque Chemistry Division Physical Chemistry and Applied Spectroscopy Group (C-PCS) Center for Integrated Nanotechnologies (CINT) and Materials Science & Technology Division (MST-7) Los Alamos National Laboratory Los Alamos New Mexico 87544 USA Experimental Condensed Matter Physics Laboratory University of Antwerp Antwerp B-2610 Belgium National Renewable Energy Laboratory Golden Colorado 80401 USA

Isolation and purification of single-walled carbon nanotubes （SWCNTs） are prerequisites for their implementation in various applications. In this work, we present a fast （-5 min）, low-cost, and easily scalable bench-top approach to the extraction of high-quality isolated SWCNTs from bundles and impurities in an aqueous dispersion. The extraction procedure, based on aqueous two-phase （ATP） separation, is widely applicable to any SWCNT source （tested on samples up to 1.7 nm in diameter） and independent of defect density, purity, diameter, and length. The extracted dispersions demonstrate that the removal of large aggregates, small bundles, and impurities is comparable to that by density gradient ultracentrifugation, but without the need for high-end instrumentation. Raman and fluorescence-excitation spectroscopy, single-nanotube fluorescence imaging, atomic force and transmission electron microscopy, and thermogravimetric analysis all confirm the high purity of the isolated SWCNTs. By predispersing the SWCNTs without sonication （only gentle stirring）, full-length, pristine SWCNTs can be isolated （tested up to 20 μm）. Hence, this simple ATP method will find immediate application in the generation of SWCNT materials for all levels of nanotube research and applications, from fundamental studies to high-performance devices.

关键词： carbon nanotubes aqueous two-phase (ATP)separation aggregate removal isolation sorting

Generation of knockout rabbits using transcription activator-like effector nucleases

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Cell Regeneration 2014年第1期3卷 21-29页

作者： Yu Wang Nana Fan Jun Song juan Zhong Xiaogang Guo Weihua Tian Quanjun Zhang Fenggong Cui Li Li Philip N Newsome Jon Frampton miguel A Esteban Liangxue Lai Key Laboratory of Regenerative Biology of the Chinese Academy of Sciences and Guangdong Provincial Key Laboratory of Stem Cells and Regenerative Medicine South China Institute for Stem Cell Biology and Regenerative MedicineGuangzhou Institutes of Biomedicine and HealthGuangzhou 510530China NIHR Liver BRU and Centre for Liver Research University of BirminghamBirminghamUK Liver and Hepatobiliary Unit Queen Elizabeth Hospital BirminghamBirminghamUK Institute for Biomedical Research College of Medical and Dental SciencesUniversity of BirminghamBirmingham B152TTUK

Zinc-finger nucleases and transcription activator-like effector nucleases are novel gene-editing platformscontributing to redefine the boundaries of modern biological research. They are composed of a non-specificcleavage domain and a tailor made DNA-binding module, which enables a broad range of genetic modifications byinducing efficient DNA double-strand breaks at desired loci. Among other remarkable uses, these nucleases havebeen employed to produce gene knockouts in mid-size and large animals, such as rabbits and pigs, *** approach is cost effective, relatively quick, and can produce invaluable models for human disease studies,biotechnology or agricultural purposes. Here we describe a protocol for the efficient generation of knockout rabbitsusing transcription activator-like effector nucleases, and a perspective of the field.

关键词： Rabbits Animal models Zinc-finger nucleases Transcription activator-like effector nucleases TALENs Genome editing Knockout

Thermodynamics of a Shallow Solar Still

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Energy and Power Engineering 2014年第9期6卷 246-265页

作者： juan Cristobal Torchia-Núnez Jaime Cervantes-de-Gortari miguel Angel Porta-Gándara Independent Energy Consultant San JoseCosta Rica Mechanical Engineering Department National University of MexicoMexico CityMexico CIBNOR La PazBCSMexico

A detailed summary of the most relevant aspects of the thermodynamics of a shallow solar still is presented, including historical features not often found in the literature. Solar distillation has grown from applying empirical knowledge to advanced modeling and simulation. Geometrical, environmental and operational parameters of the solar still to heat transfer phenomena including evaporation and condensation, are taken into account in this overview, giving a comprehensive structure and classification to the study of solar stills from the thermodynamic point of view. The article describes global parameters, such as solar radiation, wind speed and thermal insulation among others and how they have been taken into account in the literature. Also, a distinction between internal and external heat transfer phenomena is proposed for clarification. Exergy balance is included to account for thermodynamic imperfections in the several processes inside the solar still.

关键词： Solar Still Overview Thermodynamics Modeling Exergy Heat Transfer

Minimally Invasive Surgical Approach for Spinal Canal Tumors—Technique Description and Experience from a Reference Center

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Journal of Cancer Therapy 2017年第3期8卷 268-277页

作者： miguel Berbeo Roberto Diaz juan Carlos Perez Manuel Giraldo-Grueso Santiago Gutierrez María Camila Villegas juan Acevedo Oscar Feo Lee Oscar Zorro juan Gomez Carlos Lindado Pablo Harker juan Sardi Hospital Universitario San Ignacio Pontificia Universidad Javeriana Bogotá Colombia

Background: Spinal canal tumors are difficult to diagnose and treat. The traditional surgical approaches for attempting a complete excision of these lesions frequently involve big incisions and tissue dissection with high risk of postop instability and cerebrospinal fluid leakage. Also, there is a risk of neurological worsening, sometimes irreversible. Methods: We present our experience in a patient series with spinal canal tumors and describe the surgical approach with minimally invasive techniques (MIS). All of them were performed by the Neurosurgery team of the Hospital Universitario San Ignacio during the period of 2011-2016. Results: We reviewed forty patients with spinal canal tumors surgically treated with MIS techniques. 15 patients (37.5%) had Meningioma diagnosis (complete resection in 11 (73.3%), subtotal in 3 (20%) and biopsy in one patient), 10 patients (25%) with Schwannomas reached complete resection in 70% and subtotal in 30%. 5 patients had spinal cord metastasis, with complete resection in 4 patients (80%) and subtotal in 1 (20%). Other included ependymoma, astrocytoma, and miscellaneous. No patient has had cerebrospinal fluid leakage and no postoperative fusion has been required. Conclusions: The minimally invasive approach allowed complete tumors removal in a high number of patients and good postoperative results. These findings are similar and in some cases, better than the reported with traditional techniques. This MIS technique provides encouraging results. It requires a wide learning curve and a high degree of surgical experience.

关键词： Spinal Tumors Minimally Invasive Spine Surgery Surgical Technique

Energetic Analysis of Two Thermal Power Plants with Six and Seven Heaters

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Open Journal of Applied Sciences 2014年第1期4卷 6-12页

作者： miguel Toledo juan Abugaber Raúl Lugo Martín Salazar Alfredo Rodríguez Aldo Rueda Applied Hydraulics and Thermal Engineering Laboratory National Polytechnics Institute Mexico City Mexico Centro de Investigación en Ingeniería y Ciencias Aplicadas CIICAp/UAEM Cuernavaca Mexico Hydraulic Engineering and Process Department Metropolitan Autonomous University Mexico City Mexico Industrial Engineering and Mechatronics Department Tecnológico de Estudios Superiores de Ecatepec Ecatepec de Morelos Mexico

An energetic analysis of two power plants with six and seven heaters was realized in this work and also a feedwater heater was taking into consideration. This analysis considered the temperature and pressure ranges under which power generating plants work. The unit thermal consumption (UTC), the specific fuel consumption (SFC) and the specific steam consumption (SSC) were obtained for power generation. The energetic analysis to the cycles of steam with regeneration with six and seven heaters was realized. There was a difference of 0.5% in the values of UTC, SFC and SSC when the pressures of condensation changed. Also an analysis of the behavior of the thermal efficiency in relation to the rise of numbers of heater from two to seven is presented.

关键词： Energetic Analysis Feedwater Heater Thermal Efficiency Rankine Cycle

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.