Practical Maya programming with Python

CERN Document Server

Galanakis, Robert

2014-01-01

""Practical Maya Programming with Python"" is a practical tutorial packed with plenty of examples and sample projects which guides you through building reusable, independent modules and handling unexpected errors. If you are a developer looking to build a powerful system using Python and Maya's capabilities, then this book is for you. Practical Maya Programming with Python is perfect for intermediate users with basic experience in Python and Maya who want to better their knowledge and skills.

Mathematical Contributions of the Mayas, Aztecs & Incas: A Native American Curriculum Unit for Middle and High School. NATAM XIX.

Science.gov (United States)

Stodola, Janet

Written to fulfill the requirements for a University of Minnesota College of Education off-campus Indian education course for public school teachers, this Native American curriculum unit for middle and high school reflects the mathematical achievements of the Maya, Aztec, and Inca Indians. The number systems, notation, and calendar techniques of…

Deep data science to prevent and treat growth faltering in Maya children.

Science.gov (United States)

Varela-Silva, M I; Bogin, B; Sobral, J A G; Dickinson, F; Monserrat-Revillo, S

2016-06-01

The Maya people are descended from the indigenous inhabitants of southern Mexico, Guatemala and adjacent regions of Central America. In Guatemala, 50% of infants and children are stunted (very low height-for-age), and some rural Maya regions have >70% children stunted. A large, longitudinal, intergenerational database was created to (1) provide deep data to prevent and treat somatic growth faltering and impaired neurocognitive development, (2) detect key dependencies and predictive relations between highly complex, time-varying, and interacting biological and cultural variables and (3) identify targeted multifactorial intervention strategies for field testing and validation. Contributions to this database included data from the Universidad del Valle de Guatemala Longitudinal Study of Child and Adolescent Development, child growth and intergenerational studies among the Maya in Mexico and studies about Maya migrants in the United States.

Entre velos: Maya para contrabajo

Directory of Open Access Journals (Sweden)

Rosa María Rodríguez Hernández

2014-01-01

Full Text Available Maya para contrabajo se materializa a partir de una imagen de Pepe Romero, cuyo texto interpreta a La decadencia de la mentira de Oscar Wilde. La estructura de Maya es binaria, especular y asimétrica; su poética obedece al juego verdad/mentira que subyace en la obra artística y en la vivencia del artista. Maya trae a la memoria las voces de los Upanishad, Schopenhauer, Shakespeare y Beethoven, influencias éstas en la obra de Wagner y, todas ellas, en la de Eliot. Los aspectos gestuales y visuales de Maya entrelazan con la danza de Pina Bausch y con la retórica (hypotiposis.

Mastering Autodesk Maya 2014

CERN Document Server

Palamar, Todd

2013-01-01

Hands-on intermediate-to-advanced coverage of the leading 3D software Autodesk Maya is the industry-leading 3D animation and effects software used in movies, visual effects, games, and other genres. If you already know the basics of Maya and are ready to elevate your skills, then this book is for you. Nearly 1,000 pages are packed with organized, professional, and valuable insight on the leading 3D application on the market, enabling you to unlock the software's more complex features. Ideal as both a tutorial and study guide for the Autodesk Maya exam, this Autodesk Official Press

Maya Studio Projects Dynamics

CERN Document Server

Palamar, Todd

2009-01-01

The only hands-on book devoted to mastering Maya's dynamics tools for water, wind, and fire. In the world of animation, the ability to create realistic water, wind, and fire effects is key. Autodesk Maya software includes powerful dynamics tools that have been used to design breathtaking effects for movies, games, commercials, and short films. This professional guide teaches you the primary techniques you need to make the most of Maya's toolkit, so you'll soon be creating water that ripples, gusting winds and gentle breezes, and flickering fires the way Hollywood pros do. The one-of-a-kind boo

Introducing Autodesk Maya 2012

CERN Document Server

Derakhshani, Dariush

2011-01-01

A practical, step-by-step guide to Maya 2012 This book is the ideal primer to getting started with Maya, the premier 3D animation and effects software used in movies, visual effects, games, cartoons, short films, and commercials. You'll learn the Maya interface and the basics of modeling, texturing, animating, and visual effects. Professional visual effects artist and instructor Dariush Derakhshani explains the nuances of the complex software, while creative tutorials offer realistic, professional challenges for those new to 3D. You'll be up and running in no time with the world's most popular

Freeing Maya Angelou's Caged Bird

OpenAIRE

Graham, Joyce L.

1991-01-01

This study involves a comprehensive examination of one book, Maya Angelou's autobiographical I Know Why Why the Caged Bird Sings, since it was first published in 1970. Recognized as an important literary work, the novel is used in many middle and secondary school classrooms throughout the united States. Additionally, the work often is challenged in public schools on the grounds of its sexual and/or racial content. The purpose of this study included establishing th...

Population structure of the Classic period Maya.

Science.gov (United States)

Scherer, Andrew K

2007-03-01

This study examines the population structure of Classic period (A.D. 250-900) Maya populations through analysis of odontometric variation of 827 skeletons from 12 archaeological sites in Mexico, Guatemala, Belize, and Honduras. The hypothesis that isolation by distance characterized Classic period Maya population structure is tested using Relethford and Blangero's (Hum Biol 62 (1990) 5-25) approach to R matrix analysis for quantitative traits. These results provide important biological data for understanding ancient Maya population history, particularly the effects of the competing Tikal and Calakmul hegemonies on patterns of lowland Maya site interaction. An overall F(ST) of 0.018 is found for the Maya area, indicating little among-group variation for the Classic Maya sites tested. Principal coordinates plots derived from the R matrix analysis show little regional patterning in the data, though the geographic outliers of Kaminaljuyu and a pooled Pacific Coast sample did not cluster with the lowland Maya sites. Mantel tests comparing the biological distance matrix to a geographic distance matrix found no association between genetic and geographic distance. In the Relethford-Blangero analysis, most sites possess negative or near-zero residuals, indicating minimal extraregional gene flow. The exceptions were Barton Ramie, Kaminaljuyu, and Seibal. A scaled R matrix analysis clarifies that genetic drift is a consideration for understanding Classic Maya population structure. All results indicate that isolation by distance does not describe Classic period Maya population structure. (c) 2006 Wiley-Liss, Inc.

Maya Studio Projects Photorealistic Characters

CERN Document Server

Palamar, Todd

2011-01-01

Create realistic characters with Maya tools and this project-based book Maya character generation tools are extremely sophisticated, and there's no better way to learn all their capabilities than by working through the projects in this hands-on book. This official guide focuses on understanding and implementing Maya's powerful tools for creating realistic characters for film, games, and TV. Use a variety of tools to create characters from skeleton to clothing, including hairstyles and facial hair, and learn how to use Performance Capture. A DVD includes supplementary videos, project support fi

Entre velos: Maya para contrabajo

OpenAIRE

Rosa María Rodríguez Hernández

2014-01-01

Maya para contrabajo se materializa a partir de una imagen de Pepe Romero, cuyo texto interpreta a La decadencia de la mentira de Oscar Wilde. La estructura de Maya es binaria, especular y asimétrica; su poética obedece al juego verdad/mentira que subyace en la obra artística y en la vivencia del artista. Maya trae a la memoria las voces de los Upanishad, Schopenhauer, Shakespeare y Beethoven, influencias éstas en la obra de Wagner y, todas ellas, en la de Eliot. Los aspectos gestuales y visu...

The ‘End’ of the Maya Long Count? 2012 and the Classic Maya

Directory of Open Access Journals (Sweden)

Erik Boot

2013-06-01

Full Text Available The second meeting of the AISI (Associazione Italiana Studi Iberoamericani was dedicated to “Apocalypse” in Latin American literature. In the year of 2012 this particular subject was chosen as various non- and pseudo-scientific and New Age publications hold that the Maya Long Count ends in 2012, more specifically on December 21. In this essay I present a short overview on how the idea of an ‘end’ of the Maya Long Count emerged, which ancient Maya hieroglyphic texts (from the Late Classic Maya period, ca. A.D. 550-900 refer to this particular date, and what the only text (from the site of Tortuguero, Tabasco, Mexico that may tell us something on 2012 reveals. I also present a short historic overview of the quality of the drawing of the Tortuguero text and how these influenced earlier decipherments, translations, and interpretations of this text. Ultimately, the hieroglyphic text itself is analyzed and one detail is discusses in more detail, the verb root tzutz- and which different, but not necessarily mutually exclusive, meanings it has in Mayan languages.

Acculturation stress among Maya in the United States.

Science.gov (United States)

Millender, Eugenia

2012-01-01

Abstract: As health care disparities become more evident in our multicultural nation, culture sensitive health research needs to be a priority in order for good health care to take place. This article will explore the literature related to acculturation stress and mental health disparities among the Mayan population. Literatures of similar but distinct groups are included due to the limited amount of research of the Mayan population. Using Leiniger's Transcultural nursing theory, these findings suggest that nurses have a large gap to fill to address the mental health disparities of specific cultural groups like the indigenous Maya, thereby satisfying their nursing obligations.

MAYAS, SPIRITUALITY, AND THE UNFINISHED HISTORY OF CONFLICT IN GUATEMALA.

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Servando Z. Hinojosa

2012-10-01

Full Text Available Maya spiritual practice in Guatemala has been actively challenged by mainstream religions and by pressures originating from other institutions. Many Maya ritualists have been directly reproached by religious leaders and have been targeted by a state apparatus that associates rural Maya life with insurgency. As a result, many Maya spiritual elements have been pushed to, and kept at, the margins of society. Focusing on the past two decades, this essay reviews how Mayas nevertheless maintain an active ritual life. They do this by engaging in a close relationship with the spirit-owners of the landscape, beings upon whom humans depend for their sustenance and life. They do this, also, in the face of many challenges from organized religions, the educational system, and the military. Having considered the effects of these institutions upon Maya spirituality, I then put forward some concerns Mayas face when addressing how to value and promote Maya spiritual practices in Guatemala. In addition to encouraging young Mayas to uphold their heritage, Mayas may need to prevail upon Catholic and evangelical Protestant congregations to suspend judgment about Maya spirituality and to acknowledge its far-reaching importance in culturally pluralistic society.

Diffusion Of Indigo Molecules Inside The Palygorskite Clay Channels

OpenAIRE

Dejoie , Catherine; Martinetto , Pauline; Dooryhee , Eric; Van Eslande , Elsa; Blanc , Sylvie; Bordat , Patrice; Brown , Ross; Porcher , Florence; Anne , Michel

2011-01-01

International audience; The search for durable dyes led several past civilizations to develop artificial pigments. Maya Blue (MB), manufactured in pre-Columbian Mesoamerica, is one of the best known examples of an organic-inorganic hybrid material. Its durability is due to the unique association of indigo molecule and palygorskite, a particular fibrous clay occurring in Yucatan. Despite 50 years of sustained interest, the microscopic structure of MB and its relation to the durability remain o...

Ownership of Language in Yucatec Maya Revitalization Pedagogy

Science.gov (United States)

Guerrettaz, Anne Marie

2015-01-01

This classroom-based study examined a Yucatec Maya language course for teachers and the pedagogical implementation of national language policy in Mexico. Analysis of this teacher education program focused on various dimensions of teachers' Maya-language expertise, the teaching of the emergent standard Maya, and hegemonic constructions of…

Stars Influence on the Earth in Maya Culture: Stars and Planets in Maya Culture

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Emanuel George Oprea

2015-11-01

Full Text Available The Mesoamerican Culture of Maya’s was one of the ancient and advanced cultures of the American continent and they influenced other Amerindian peoples. The life of Maya people, of the Earth itself and of the Universe is set and constructed around Maya Calendar and has a cyclic character as a direct influence of the stars. Many centuries the Western civilization with the its linear Calendar had not accepted the ideas of the possible influence of the stars and planets to peoples lives. The end of the last century and the beginning of XXI’s had started to demonstrate the opposite. The present work tries to show the process of meeting and intersection of the ancient ideas of Maya civilization and some of new ideas from the modern sciences.

Transient electromagnetic mapping of clay units in the San Luis Valley, Colorado

Science.gov (United States)

Fitterman, David V.; Grauch, V.J.S.

2010-01-01

Transient electromagnetic soundings were used to obtain information needed to refine hydrologic models of the San Luis Valley, Colorado. The soundings were able to map an aquitard called the blue clay that separates an unconfined surface aquifer from a deeper confined aquifer. The blue clay forms a conductor with an average resistivity of 6.9 ohm‐m. Above the conductor are found a mixture of gray clay and sand. The gray clay has an average resistivity of 21 ohm‐m, while the sand has a resistivity of greater than 100 ohm‐m. The large difference in resistivity of these units makes mapping them with a surface geophysical method relatively easy. The blue clay was deposited at the bottom of Lake Alamosa which filled most of the San Luis Valley during the Pleistocene. The geometry of the blue clay is influenced by a graben on the eastern side of the valley. The depth to the blue clay is greater over the graben. Along the eastern edge of valley the blue clay appears to be truncated by faults.

The use of blunted Maya crude as alternating fuel to fuel oil; Uso de crudo Maya despuntado como combustiononble alterno al combustoleo

Energy Technology Data Exchange (ETDEWEB)

Salinas Bravo, Victor M.; Diego Marin, Antonio; Porcayo C; Jesus [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

2001-07-01

The Mexican fuel oil is characterized by its high viscosity and elevated contents of sulfur and vanadium. This particularity determines a problematic characteristic in the steam generators that use this fuel. Our country produces three types of crude petroleum: Olmeca, Istmo and Maya. The difference between these crudes remains in its density and the sulfur content. The Olmeca crude and the Istmo are classified as super-light and light, respectively; whereas the Maya crude is classified as a heavy crude, with a density of 1.0 to 0.92 g/cm and a minimum sulfur content of 3.3 %. For this reason the processing of the Maya crude is seen as an alternative. A table with the physicochemical analysis and properties of a fuel oil and the blunted Maya crude is given, and another one with the quantitative chemical analysis of some metals in fuel oil and in the blunted Maya crude. The stability tests of the fuel are studied giving a comparison of the effect of the aging time on the viscosity of a fuel oil and of the blunted Maya crude at 60 Celsius degrees. As well as a graph of thermograms obtained of a blunted Maya crude sample and of a typical fuel oil. Finally the corrosion tests are described that allow to know in real time the degradation process by corrosion of the materials. [Spanish] El combustoleo mexicano se caracteriza por su alta viscosidad y elevados contenidos de azufre y vanadio. Esta particularidad determina una problematica caracteristica en los generadores de vapor que utilizan este combustible. Nuestro pais produce tres tipos de petroleo crudo: Olmeca, Istmo y Maya. La diferencia entre estos crudos estriba en su densidad y el contenido de azufre. El crudo Olmeca y el Istmo estan clasificados como superligero y ligero, respectivamente; mientras que el crudo Maya esta clasificado como un crudo pesado, con una densidad de 1.0 a 0.92 g/cm y un contenido minimo de azufre de 3.3 %.Con el proposito se busca la alternativa de procesar el crudo Maya. Se da una tabla

Cumulative Trauma Among Mayas Living in Southeast Florida.

Science.gov (United States)

Millender, Eugenia I; Lowe, John

2017-06-01

Mayas, having experienced genocide, exile, and severe poverty, are at high risk for the consequences of cumulative trauma that continually resurfaces through current fear of an uncertain future. Little is known about the mental health and alcohol use status of this population. This correlational study explored t/he relationship of cumulative trauma as it relates to social determinants of health (years in the United States, education, health insurance status, marital status, and employment), psychological health (depression symptoms), and health behaviors (alcohol use) of 102 Guatemalan Mayas living in Southeast Florida. The results of this study indicated that, as specific social determinants of health and cumulative trauma increased, depression symptoms (particularly among women) and the risk for harmful alcohol use (particularly among men) increased. Identifying risk factors at an early stage before serious disease or problems are manifest provides room for early screening leading to early identification, early treatment, and better outcomes.

Mapping The Ancient Maya Landscape From Space

Science.gov (United States)

Sever, Tom; Arnold, James E. (Technical Monitor)

2002-01-01

The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3-I radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the bajos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of bajos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the bajo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The use of the bajos for farming is also an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a question that

Autodesk Maya 2013 Essentials

CERN Document Server

Naas, Paul

2012-01-01

Recommnded text for those preparing for the Maya Associate exam Maya, the industry-leading 3D animation and effects software used in movies, games, cartoons, and commercials, is challenging to learn. This full-color guide features approachable, hands-on exercises and additional task-based tutorials that allow new users to quickly become productive with the program and familiar with its workflow in a professional environment. You'll learn the basics of modeling, texturing, animating, and lighting; explore different parts of the production pipeline; and practice on some real-world projects. Ma

Collapse, conquest and Maya survival at Lamanai, Belize

OpenAIRE

Graham, Elizabeth

2000-01-01

The Maya civilization of Central America prompts visions of mysterious stone temples now buried in tropical forest. It is commonly supposed to have collapsed suddenly in the ninth century AD, but some Maya settlements, such as Lamanai, survived into the colonial period. Here a new member of the Institute's academic staff gives a personal account of how working in Belize transformed her understanding of Maya civilization and its aftermath.

A water storage adaptation in the maya lowlands.

Science.gov (United States)

Scarborough, V L; Gallopin, G G

1991-02-08

Prehispanic water management in the Maya Lowlands emphasized collection and storage rather than the canalization and diversion accentuated in highland Mexico. Reexamination of site maps of the ancient Maya city of Tikal, Guatemala, has revealed an important, overlooked factor in Maya centralization and urban settlement organization. In a geographical zone affected by an extended dry season and away from permanent water sources, large, well-planned reservoirs provided resource control as well as political leverage.

Collapse, conquest and Maya survival at Lamanai, Belize

Directory of Open Access Journals (Sweden)

Elizabeth Graham

2000-11-01

Full Text Available The Maya civilization of Central America prompts visions of mysterious stone temples now buried in tropical forest. It is commonly supposed to have collapsed suddenly in the ninth century AD, but some Maya settlements, such as Lamanai, survived into the colonial period. Here a new member of the Institute's academic staff gives a personal account of how working in Belize transformed her understanding of Maya civilization and its aftermath.

Directional layouts in central lowland Maya settlement

DEFF Research Database (Denmark)

Bevan, Andrew; Jobbová, Eva; Helmke, Christophe

2013-01-01

This paper suggests the existence of non-random, directional patterns in the location of housemounds across the Late Classic Maya settlement landscape at Baking Pot, Belize, and then explores the wider implications of this patterning in the central Maya lowlands. It introduces an anisotropic method...

Maya medicine in the biological gaze: bioprospecting research as herbal fetishism.

Science.gov (United States)

Nigh, Ronald

2002-06-01

The relationship of human societies to territory and natural resources is being drastically altered by a series of global agreements concerning trade, intellectual property, and the conservation and use of genetic resources. Through a characteristic style of collective appropriation of their tropical ecosystems, Maya societies have created local institutions for governing access to their common resources. However, new mechanisms of global governance require access to Maya biodiversity for world commercial interests. The Chiapas Highland Maya already face this prospect in the International Cooperative Biodiversity Group drug discovery project, which proposes to use Maya medical knowledge to screen plants for potential pharmaceuticals. The ethnobiological focus of the project emphasizes the naturalistic aspects of Maya medicine, primarily the use of herbal remedies. This biological gaze decontextualizes the situated knowledge of Maya healers, ignoring the cultural context in which they create and apply that knowledge. The search for raw materials for the production of universal medical technology results in symbolic violence to the cultural logic of Maya peoples. Only the full recognition of Maya peoples' collective rights to territory and respect for their local common-resource institutions will provide ultimate protection for their cultural and natural patrimony.

The Costa Maya:  Evolution of a Touristic Landscape La Costa Maya : évolution d'un paysage touristique La Costa Maya : evolución de un paisaje turístico

Directory of Open Access Journals (Sweden)

Klaus J. Meyer-Arendt

2010-06-01

Full Text Available La Costa Maya est une région côtière du sud du Quintana Roo (Mexique, proche de l'îlet Ambergris au Bélize. Contrairement à la côte caribéenne du Mexique qui a souffert du développement du tourisme de masse à Cancun et le long de la Riviera Maya, la Costa Maya s'est orientée vers un développement durable avec notamment une faible densité de construction et le développement de l'écotourisme.Le développement s'est concentré autour de Puerto Costa Maya où un terminal de croisière a été construit en 2001. La station balnéaire (balneario de Majahual est devenue dépendante des 10-12 bateaux de touristes qui débarquaient chaque semaine. En dépit d'importants plans de développement, les plages reculées de la Costa Maya accueillaient tout au plus des écotouristes aisés et du tourisme lié à la plongée sous-marine.Le cyclone Dean, de catégorie 5, a dévasté le paysage en août 2007 et le rétablissement économique n'a pu être entamé que fin 2008, après la réouverture du terminal de croisière et la reconstruction de Majahual. Fin 2009, le trafic de croisière n'a pas retrouvé son niveau d'avant Dean et la récession mondiale couplée avec la grippe porcine et les violences liées à la drogue ont fait diminuer le tourisme en provenance des Etats-Unis. On ignore à quel niveau les nouvelles infrastructures tels l'aéroport international de Tulum qui propose un itinéraire de Chetumal à la plage et le nouveau complexe hôtelier à Xahuayxel, stimuleront la Costa Maya mexicaine créant peut-être une autoroute côtière reliée à San Pedro au Bélize.The Costa Maya is a vernacular coastal region of southeastern Quintana Roo (Mexico and adjacent Ambergris Cay, Belize.  As Mexico’s Caribbean coast suffered many growth pains associated with mass tourism development in Cancun and along the Riviera Maya, the Costa Maya by contrast was projected for more sustainable development including low-density housing and

Getting started in 3D with Maya

CERN Document Server

Watkins, Adam

2012-01-01

Deliver professional-level 3D content in no time with this comprehensive guide to 3D animation with Maya. With over 12 years of training experience, plus several award winning students under his belt, author Adam Watkins is the ideal mentor to get you up to speed with 3D in Maya. Using a structured and pragmatic approach Getting Started in 3D with Maya begins with basic theory of fundamental techniques, then builds on this knowledge using practical examples and projects to put your new skills to the test. Prepared so that you can learn in an organic fashion, each chapter builds on the know

Synchrotron and Simulations Techniques Applied to Problems in Materials Science: Catalysts and Azul Maya Pigments

International Nuclear Information System (INIS)

Chianelli, R.

2005-01-01

Development of synchrotron techniques for the determination of the structure of disordered, amorphous and surface materials has exploded over the past twenty years due to the increasing availability of high flux synchrotron radiation and the continuing development of increasingly powerful synchrotron techniques. These techniques are available to materials scientists who are not necessarily synchrotron scientists through interaction with effective user communities that exist at synchrotrons such as the Stanford Synchrotron Radiation Laboratory (SSRL). In this article we review the application of multiple synchrotron characterization techniques to two classes of materials defined as ''surface compounds.'' One class of surface compounds are materials like MoS 2-x C x that are widely used petroleum catalysts used to improve the environmental properties of transportation fuels. These compounds may be viewed as ''sulfide supported carbides'' in their catalytically active states. The second class of ''surface compounds'' is the ''Maya Blue'' pigments that are based on technology created by the ancient Maya. These compounds are organic/inorganic ''surface complexes'' consisting of the dye indigo and palygorskite, a common clay. The identification of both surface compounds relies on the application of synchrotron techniques as described in this report

Stones of Light: The Use of Crystals in Maya Divination

DEFF Research Database (Denmark)

McGraw, John J.

2016-01-01

In this chapter, I aim to bridge the rewarding archaeological contributions from the earlier part of this volume to ethnographic work performed among contemporary Mayas, particularly as informed by ritual specialists. In considering the ritual use of quartz crystals by living Mayas we may gain...... of functional analysis that situate archaeological and ethnographic data without projecting a particularism onto Maya contexts that may be inappropriate given the local epistemologies. Finally, I draw from cognitive science and religious studies to present a theory regarding the popularity and importance...... of quartz crystals in ritual activity, not only among the Maya, but worldwide. It is hoped that the analyses presented not only clarify ideas regarding quartz crystals in divination, but more broadly address the nature and importance of scrying in Maya religion....

Ancient Maya Regional Settlement and Inter-Site Analysis: The 2013 West-Central Belize LiDAR Survey

Directory of Open Access Journals (Sweden)

Arlen F. Chase

2014-09-01

Full Text Available During April and May 2013, a total of 1057 km2 of LiDAR was flown by NCALM for a consortium of archaeologists working in West-central Belize, making this the largest surveyed area within the Mayan lowlands. Encompassing the Belize Valley and the Vaca Plateau, West-central Belize is one of the most actively researched parts of the Maya lowlands; however, until this effort, no comprehensive survey connecting all settlement had been conducted. Archaeological projects have investigated at least 18 different sites within this region. Thus, a large body of archaeological research provides both the temporal and spatial parameters for the varied ancient Maya centers that once occupied this area; importantly, these data can be used to help interpret the collected LiDAR data. The goal of the 2013 LiDAR campaign was to gain information on the distribution of ancient Maya settlement and sites on the landscape and, particularly, to determine how the landscape was used between known centers. The data that were acquired through the 2013 LiDAR campaign have significance for interpreting both the composition and limits of ancient Maya political units. This paper presents the initial results of these new data and suggests a developmental model for ancient Maya polities.

Les Mayas à Hollywood.

Directory of Open Access Journals (Sweden)

Boris Jeanne

2007-02-01

Full Text Available Les Mayas de nos jours ce sont surtout des grandes pyramides au milieu de la forêt à un jet d’avion de Cancún : pour nombre de touristes américains et européens, c’est une occasion de s’acoquiner avec la culture, la grande culture des civilisations perdues, en continuant de boire des piña coladas le soir au bord de la plage. Et puis au mois de décembre les Mayas ont débarqué en force dans le paysage culturel local des Américains et des Européens, dans leurs cinémas, au moyen de deux films in...

Imaginando a los mayas de hoy: autorrepresentación y política

Directory of Open Access Journals (Sweden)

Ana Rosa Duarte Duarte

2008-01-01

Full Text Available En este artículo se analiza el proceso de representación y autorrepresentación de los mayas de Yucatán en Sáastal: Los hijos de la Santa Gracia, una video-ficción de cincuenta y cinco minutos. En Sáastal se pone en escena el drama de la vida cotidiana de una familia maya de acuerdo con la imaginación, tanto de los mayas que participamos en la producción como de los no mayas. Se analiza cómo la convivencia de la cultura maya con las diversas políticas civilizatorias, entre éstas, las de desarrollo, modernización y globalización, han influido en el imaginario de los mayas contemporáneos. Esta convivencia entre dos culturas ha llevado a los mayas a adoptar "identidades suaves", que les permiten actuar de acuerdo con las circunstancias. En Sáastal, los mayas "performamos", recreamos e instrumentalizamos la cultura y convertimos en ficticias nuestras propias identidades.In this article I analyze the processes of representation and self-representation of the Yucatec Maya in Sáastal: The Children of the Sacred Grace, a 55-minute video-fiction. Sáastal presents a dramatic account of the everyday life of a Yucatec Maya family as imagined both by the Maya and non-Maya participating in the production. I examine how this imaginary is influenced by the coexistence of the Mayan culture with the diverse civilizatory politics, such as the politics of development, modernization, and globalization. it is argued that this coexistence has led us, the Yucatec Maya, to adopt "soft identities" which allow us to act according to the circumstances. In Sáastal we therefore perform, recreate and instrumentalize our culture and, in this way, convert our own identities into fictions.

Impacts of Climate Change on the Collapse of Lowland Maya Civilization

Science.gov (United States)

Douglas, Peter M. J.; Demarest, Arthur A.; Brenner, Mark; Canuto, Marcello A.

2016-06-01

Paleoclimatologists have discovered abundant evidence that droughts coincided with collapse of the Lowland Classic Maya civilization, and some argue that climate change contributed to societal disintegration. Many archaeologists, however, maintain that drought cannot explain the timing or complex nature of societal changes at the end of the Classic Period, between the eighth and eleventh centuries ce. This review presents a compilation of climate proxy data indicating that droughts in the ninth to eleventh century were the most severe and frequent in Maya prehistory. Comparison with recent archaeological evidence, however, indicates an earlier beginning for complex economic and political processes that led to the disintegration of states in the southern region of the Maya lowlands that precedes major droughts. Nonetheless, drought clearly contributed to the unusual severity of the Classic Maya collapse, and helped to inhibit the type of recovery seen in earlier periods of Maya prehistory. In the drier northern Maya Lowlands, a later political collapse at ca. 1000 ce appears to be related to ongoing extreme drought. Future interdisciplinary research should use more refined climatological and archaeological data to examine the relationship between climate and social processes throughout the entirety of Maya prehistory.

How to Cheat in Maya 2012 Tools and Techniques for Character Animation

CERN Document Server

Luhta, Eric

2011-01-01

The Maya guide for animators, How to Cheat in Maya 2012 presents everything you need to know about character animation in Maya. Fully updated for the latest revision of Maya, this book provides you with complete, step-by-step walkthroughs of essential animation techniques to increase your efficiency and speed. This is an animator's workflow in book form, written by professional animators-not a software book with a few animation pointers thrown in. In addition to all the gold-mine coverage and interviews with expert animators from the previous edition, How to Cheat in Maya 2012 also features a

Recent Advances in Maya Studies Using Remotely Sensed Data

Science.gov (United States)

Sever, Tom; Irwin, Daniel; Arnold, James E. (Technical Monitor)

2001-01-01

The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3i radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the baJos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of bajos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the bajo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The combination of water management and bajo farming is an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a

The Moon In The Classic Maya World

Science.gov (United States)

Romano, Giuliano

During the Classic Period of the Maya civilization (250-900 A.D.) we have many documents in which it is possible to see the interest of this people on the principal lunar phenomena as the phases and the eclipses in particular. On a number of stelae, lintels and many other inscriptions (in Copan, Quirigua, Tikal, etc.), we can see that in correspondence of the dedication date of the monument, the Maya point out the phase of the Moon and its position in a period of six months corresponding to half year of eclipse. In some parts of the Dresda Codex (one of the four original codices of the Maya) we can see some pages in which were indicated the days of the Tzolkin calendar (the religious calendar of 260 days) in which it is possible to observe a lunar or solar eclipse. The periods of 177 or 148 days are allotted in a sequence that corresponds to the exact interval between the eclipses. The accuracy in the observations and in the calculations of the phases of the Moon, also in very old epochs, is an interesting evidence of the fundamental importance of the Moon in the Maya civilisation.

Man and climate in the Maya lowlands

Science.gov (United States)

Leyden, Barbara W.

1987-11-01

A 15-m sedimentary core from Lake Salpeten provides the first complete Holocene sequence for the lowlying Peten District, Guatemala. Today, Lake Salpeten is a brackish, calcium sulfate lake near saturation surrounded by tropical semievergreen forest. The basal pollen record depicts sparse juniper scrub surrounding a lake basin that held ephermal pools and halophytic marshes. The lake rapidly deepened to > 27 m in the early Holocene and may have been meromictic, because nearly 2 m of gypsum "mush" was deposited. Mesic forests were quickly established and persisted until the Maya entered the district 3000 yr ago and caused extensive deforestation. Any climatic information contained in the pollen record of the Maya period is thus masked, but a regional pollen sequence linked to the archaeological record is substantiated because environmental disturbance was pervasive. Local intensification of occupation and population growth are seen as an increased deposition of pollen of agricultural weeds and colluviation into the lake, while the Classic Maya collapse is marked by a temporary decline in Compositae pollen. Effects of perturbations induced by the Maya persist in the pollen and limnetic record 400 yr after the Spanish conquest.

Genetic Affiliation of Pre-Hispanic and Contemporary Mayas Through Maternal Linage.

Science.gov (United States)

Ochoa-Lugo, Mirna Isabel; Muñoz, María de Lourdes; Pérez-Ramírez, Gerardo; Beaty, Kristine G; López-Armenta, Mauro; Cervini-Silva, Javiera; Moreno-Galeana, Miguel; Meza, Adrián Martínez; Ramos, Eduardo; Crawford, Michael H; Romano-Pacheco, Arturo

2016-04-01

Maya civilization developed in Mesoamerica and encompassed the Yucatan Peninsula, Guatemala, Belize, part of the Mexican states of Tabasco and Chiapas, and the western parts of Honduras and El Salvador. This civilization persisted approximately 3,000 years and was one of the most advanced of its time, possessing the only known full writing system at the time, as well as art, sophisticated architecture, and mathematical and astronomical systems. This civilization reached the apex of its power and influence during the Preclassic period, from 2000 BCE to 250 CE. Genetic variation in the pre-Hispanic Mayas from archaeological sites in the Mexican states of Yucatan, Chiapas, Quintana Roo, and Tabasco and their relationship with the contemporary communities in these regions have not been previously studied. Consequently, the principal aim of this study was to determine mitochondrial DNA (mtDNA) variation in the pre-Hispanic Maya population and to assess the relationship of these individuals with contemporary Mesoamerican Maya and populations from Asia, Beringia, and North, Central, and South America. Our results revealed interactions and gene flow between populations in the different archaeological sites assessed in this study. The mtDNA haplogroup frequency in the pre-Hispanic Maya population (60.53%, 34.21%, and 5.26% for haplogroups A, C, and D, respectively) was similar to that of most Mexican and Guatemalan Maya populations, with haplogroup A exhibiting the highest frequency. Haplogroup B most likely arrived independently and mixed with populations carrying haplogroups A and C based on its absence in the pre-Hispanic Mexican Maya populations and low frequencies in most Mexican and Guatemalan Maya populations, although this also may be due to drift. Maya and Ciboneys sharing haplotype H10 belonged to haplogroup C1 and haplotype H4 of haplogroup D, suggesting shared regional haplotypes. This may indicate a shared genetic ancestry, suggesting more regional interaction

Compositional attribution of non-provenienced Maya polychrome vessels

International Nuclear Information System (INIS)

Bishop, R.L.; Harbottle, G.; Reents, D.J.; Sayre, E.V.; van Zelst, L.

1983-01-01

Procedures and a few of the results of the Maya ceramic project are discussed from the perspective of non-provenienced vessel attribution ranging from site specific through a more inferential level to the rather hypothetical. The examples presented serve to illustrate the manner in which compositional and stylistic covariation are viewed in an investigation of Maya Ceramic art. The large data base from neutron activation analysis including archaeologically recovered pottery as well as the stylistically and iconographically elaborate vessels requires continued refinement in our methods of statistical analysis along with gaining a greater understanding of the sources of ceramic compositional variation in the Maya area. The mutually beneficial collaboration between science, art, and archaeology are emphasized

Compositional attribution of non-provenienced Maya polychrome vessels

Energy Technology Data Exchange (ETDEWEB)

Bishop, R.L.; Harbottle, G.; Reents, D.J.; Sayre, E.V.; van Zelst, L.

1983-01-01

Procedures and a few of the results of the Maya ceramic project are discussed from the perspective of non-provenienced vessel attribution ranging from site specific through a more inferential level to the rather hypothetical. The examples presented serve to illustrate the manner in which compositional and stylistic covariation are viewed in an investigation of Maya Ceramic art. The large data base from neutron activation analysis including archaeologically recovered pottery as well as the stylistically and iconographically elaborate vessels requires continued refinement in our methods of statistical analysis along with gaining a greater understanding of the sources of ceramic compositional variation in the Maya area. The mutually beneficial collaboration between science, art, and archaeology are emphasized.

Poetizas mayas:subjetividades contra la corriente

OpenAIRE

Maya, Gloria Chacón

2013-01-01

Este ensayo examina la emergencia de poetisas mayas en México y Guatemala como parte de un movimiento indígena ás amplio que clama su derecho a la diferencia cultural. Arguyo que aunque la mujer maya está inmersa en los discursos del nacionalismo oficial, nacionalismos étnicos y feminismos occidentales, crea sus propias subjetividades multidimensionales, vía la poesía. El análisis se enfoca en la resignificación de símbolos culturales tradicionales y la negociación de cultura, poder y género....

Agua y Enfermedad Entre Algunos Grupos Mayas Durante La Colonia.

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Tañía Héléne Campos Thomas.

2006-12-01

Full Text Available Along history, The mexican People ―for all the different ethnic groups in the country― has had water in high regard in their religious corpus, either in the symbolic way or the religious level. As evidence of this we can mention the cults to Tlaloc in mesoamerica and chak in the maya region, and the numerous depictions produced by chronicle writers as well as the ones found in the maya codices containing rites and giving close records of the beliefs in which water had a fundamental role. Similarly, the maya culture nowadays preserves that same close relation between water and health-illness. This article is a first investigative look into this subject intendingto restrict time and objectives and also with the aim of recording the way in which some maya ethnic groups were related to water during the colonial period. despite the colonial period was the historical framework imposed as the limit to the present paper, it has been inevitable to make reference to customs and activities of contemporary maya groups.

Maya Angelou's Children's Books: Inspiration for Turning Poetry into Music

Science.gov (United States)

Beegle, Amy C.

2014-01-01

This column presents books for children penned by Maya Angelou. These poems and stories, based on her experiences as an African American woman living in the United States, Egypt, Ghana, and South Africa, include extraordinary photography and artwork. Suggestions for inclusion in the general music classroom are provided.

The Ancient Maya Landscape from Space

Science.gov (United States)

Sever, T.; Arnold, James E. (Technical Monitor)

1999-01-01

The Peten, once inhabited by a population of several million before the collapse of the ancient Maya in the 10th and 11th centuries, is being repopulated toward its former demographic peak. Environmental dynamics, however, impose severe constraints to further development. Current practices in subsistence, commercial agriculture, and cattle raising are causing rapid deforestation resulting in the destruction of environmental and archeological resources. The use of remote sensing and Geographic Information Systems (GIS) technology is a cost-effective methodology for addressing issues in Maya archeology as well as monitoring the environmental impacts being experienced by the current population.

Maya Studio Projects Texturing and Lighting

CERN Document Server

Lanier, Lee

2011-01-01

Learn to create realistic digital assets for film and games with this project-based guide Focused entirely on practical projects, this hands-on guide shows you how to use Maya's texturing and lighting tools in real-world situations. Whether you need to sharpen your skills or you're looking to break into the field for the first time, you'll learn top industry techniques for this important skill as you follow the instructions for several specific projects. You can even create your own version, using final Maya scene files to validate results. The companion DVD includes supplemental videos, proje

An Iterative Approach to Ground Penetrating Radar at the Maya Site of Pacbitun, Belize

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Sheldon Skaggs

2016-09-01

Full Text Available Ground penetrating radar (GPR surveys provide distinct advantages for archaeological prospection in ancient, complex, urban Maya sites, particularly where dense foliage or modern debris may preclude other remote sensing or geophysical techniques. Unidirectional GPR surveys using a 500 MHz shielded antenna were performed at the Middle Preclassic Maya site of Pacbitun, Belize. The survey in 2012 identified numerous linear and circular anomalies between 1 m and 2 m deep. Based on these anomalies, one 1 m × 4 m unit and three smaller units were excavated in 2013. These test units revealed a curved plaster surface not previously found at Pacbitun. Post-excavation, GPR data were reprocessed to best match the true nature of excavated features. Additional GPR surveys oriented perpendicular to the original survey confirmed previously detected anomalies and identified new anomalies. The excavations provided information on the sediment layers in the survey area, which allowed better identification of weak radar reflections of the surfaces of a burnt, Middle Preclassic temple in the northern end of the survey area. Additional excavations of the area in 2014 and 2015 revealed it to be a large square structure, which was named El Quemado.

Los mayas del altiplano: supervivencia indígena en Chiapas y Guatemala

OpenAIRE

Lovell, W. George

2002-01-01

En el contexto americano, pocos grupos indígenas han demostrado la capacidad de sobrevivir a lo largo de la historia como los mayas del altiplano. Hoy día en Chiapas existen más de un millón de indígenas mayas, un número que asciende a cinco o seis millones en el caso de Guatemala. Los pueblos mayas han respondido a la invasión y a la dominación para conservar elementos importantes de su cultura. Este artículo discute las formas en que los mayas del altiplano se han adaptado para sobrevivir a...

Los hacendados y rancheros mayas de Yucatán en el siglo XIX Maya hacendados and rancheros from Yucatán in the 19th Century

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Laura Machuca Gallegos

2010-01-01

Full Text Available No sólo los grupos "blancos" y pudientes de la sociedad tuvieron haciendas, sino también los mayas. Al ser la hacienda una de las pocas actividades económicas productivas que se podían llevar a cabo en la península, algunos mayas (si bien son minoría se volvieron propietarios, incluso tuvieron trabajadores adeudados; por tanto, no permanecieron al margen del desarrollo económico y participaron activamente de éste. Así, en este trabajo nos ocupamos de los amos mayas, seguimos algunas de sus estrategias y reconstruimos sus lazos y sus relaciones. La principal fuente utilizada han sido documentos de carácter notarial, en particular los testamentos, de los cuales se han estudiado algunas variables como la de cónyuge, albacea testamentario y testigo.Haciendas were not exclusive for "white" powerful groups, since they were available for the Maya. Hacienda was one of the only productive economic activities in the peninsula, so the Maya (in spite of being a minority became the owners. They even had debtor workers. They were not marginalized from economic development but rather participated actively in it. This paper studies Maya masters by following some of their strategies and reconstructing both their binds and relations. Our main source are notarial documents, particularly testaments, where some variables like spouse, testamentary executor and witness are studied.

Objetual Regime of the Maya during Classic period, a proposal

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Antonio Jaramillo Arango

2016-06-01

Full Text Available Within the academic archaeology of the 20th Century, objects were only considered as sources for understanding human action. Based on recent theoretic anthropological proposals, this paper proposes a recursive archaeology, that is, to include the Classic Maya concepts as part of our analysis in order to understand things as truly protagonists of social relationships. In the Maya area, objects have different ways of being in the world which have been identified by the archeology of the Classic period: person-objects, parts of a dividual body and machines. These three ways are explored here through archaeologic contexts and epigraphic texts with the aim of approaching the construction of reality of the Classic Maya. With a multidisciplinary analysis that includes archaeology, epigraphy, history, linguistics and anthropology, a high number of examples coming from different regions in the Maya area is examined. Thus, an overall view of this phenomenon is presented.

Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands

Science.gov (United States)

Douglas, Peter M. J.; Pagani, Mark; Canuto, Marcello A.; Brenner, Mark; Hodell, David A.; Eglinton, Timothy I.; Curtis, Jason H.

2015-01-01

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800–950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period. PMID:25902508

Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands.

Science.gov (United States)

Douglas, Peter M J; Pagani, Mark; Canuto, Marcello A; Brenner, Mark; Hodell, David A; Eglinton, Timothy I; Curtis, Jason H

2015-05-05

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800-950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

PROBİYOTİK MAYA : SACCHAROMYCES BOULARDİİ

OpenAIRE

Alkan, Rezan

2013-01-01

Probiyotikler uygun miktarlarda kullanıldığında konakçı sağlığı üzerinde yararları olan, bağırsakta canlı kalabilen ,sindirime dirençli bakteri ve maya gibi canlı mikroorganizmalar olarak tanımlanmaktadır. Saccharomyces boulardii  patojen olmayan bir maya olup, tedavi edici olarak kullanılmaktadır. Kontrollü olarak yapılan klinik çalışmalarda S.boulardii’nin çeşitli bağırsak hastalıklarının önlenmesi ve ...

Cacao usage by the earliest Maya civilization.

Science.gov (United States)

Hurst, W Jeffrey; Tarka, Stanley M; Powis, Terry G; Valdez, Fred; Hester, Thomas R

2002-07-18

The Maya archaeological site at Colha in northern Belize, Central America, has yielded several spouted ceramic vessels that contain residues from the preparation of food and beverages. Here we analyse dry residue samples by using high-performance liquid chromatography coupled to atmospheric-pressure chemical-ionization mass spectrometry, and show that chocolate (Theobroma cacao) was consumed by the Preclassic Maya as early as 600 bc, pushing back the earliest chemical evidence of cacao use by some 1,000 years. Our application of this new and highly sensitive analytical technique could be extended to the identification of other ancient foods and beverages.

Religión, fiestas y centros ceremoniales mayas de la Cruz Parlante

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Manuel Buenrostro Alba

2015-07-01

Full Text Available En el trabajo se describe el principal santo de los mayas de Quintana Roo, la Cruz Parlante, así como los centros ceremoniales y las fiestas tradicionales relacionadas con esta advocación. Se incluyen datos etnográficos que describen el contexto en el que se centra el estudio. La Cruz Parlante permite a los mayas de Quintana Roo seguir existiendo y los protege, pero para ello debe estar custodiada por los propios mayas.

Los mayas del altiplano: supervivencia indígena en Chiapas y Guatemala

Directory of Open Access Journals (Sweden)

Lovell, W. George

2002-06-01

Full Text Available En el contexto americano, pocos grupos indígenas han demostrado la capacidad de sobrevivir a lo largo de la historia como los mayas del altiplano. Hoy día en Chiapas existen más de un millón de indígenas mayas, un número que asciende a cinco o seis millones en el caso de Guatemala. Los pueblos mayas han respondido a la invasión y a la dominación para conservar elementos importantes de su cultura. Este artículo discute las formas en que los mayas del altiplano se han adaptado para sobrevivir a casi cinco siglos de conquista, identificando tres fases claves en su trayectoria histórica: (1 la experiencia colonial, que abarca los años entre 1524 y 1821; (2 una época de reforma y revolución, que corre de 1821 a 1954; y (3 un período de marginalización y descuido desde 1954 en adelante. Pese al desfío, los mayas del altiplano están equipados culturalmente para perdurar.

Classic Maya civilization collapse associated with reduction in tropical cyclone activity

Science.gov (United States)

Medina, M. A.; Polanco-Martinez, J. M.; Lases-Hernández, F.; Bradley, R. S.; Burns, S. J.

2013-12-01

In light of the increased destructiveness of tropical cyclones observed over recent decades one might assume that an increase and not a decrease in tropical cyclone activity would lead to societal stress and perhaps collapse of ancient cultures. In this study we present evidence that a reduction in the frequency and intensity of tropical Atlantic cyclones could have contributed to the collapse of the Maya civilization during the Terminal Classic Period (TCP, AD. 800-950). Statistical comparisons of a quantitative precipitation record from the Yucatan Peninsula (YP) Maya lowlands, based on the stalagmite known as Chaac (after the Mayan God of rain and agriculture), relative to environmental proxy records of El Niño/Southern Oscillation (ENSO), tropical Atlantic sea surface temperatures (SSTs), and tropical Atlantic cyclone counts, suggest that these records share significant coherent variability during the TCP and that summer rainfall reductions between 30 and 50% in the Maya lowlands occurred in association with decreased Atlantic tropical cyclones. Analysis of modern instrumental hydrological data suggests cyclone rainfall contributions to the YP equivalent to the range of rainfall deficits associated with decreased tropical cyclone activity during the collapse of the Maya civilization. Cyclone driven precipitation variability during the TCP, implies that climate change may have triggered Maya civilization collapse via freshwater scarcity for domestic use without significant detriment to agriculture. Pyramid in Tikal, the most prominent Maya Kingdom that collapsed during the Terminal Classic Period (circa C.E. 800-950) Rainfall feeding stalagmites inside Rio Secreto cave system, Yucatan, Mexico.

Peopling the past: New perspectives on the ancient Maya

OpenAIRE

Robin, Cynthia

2001-01-01

The new direction in Maya archaeology is toward achieving a greater understanding of people and their roles and their relations in the past. To answer emerging humanistic questions about ancient people's lives Mayanists are increasingly making use of new and existing scientific methods from archaeology and other disciplines. Maya archaeology is bridging the divide between the humanities and sciences to answer questions about ancient people previously considered bey...

Una historia de la religión de los antiguos mayas

OpenAIRE

Baudez, Claude-François

2013-01-01

Estudio cuyo objetivo es abordar la religión de los antiguos mayas desde una perspectiva histórica en su proceso evolutivo, el cual abarca los periodos clásico y posclásico y abordar hasta qué punto la religión maya se vio simultáneamente afectada por el declive de la civilización clásica y por la infiltración de rasgos culturales del Altiplano mexicano. Los análisis tradicionales de la religión de los antiguos mayas permanecen exclusivamente al acecho de las continuidades; luego, concluye...

Politics in the Western Maya Region (II: Emblem Glyphs

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Péter Bíró

2012-01-01

Full Text Available In a series of articles I reflect on the use of various expressions which are connected to what we call the political in the inscriptions of the Classic Maya Western Region. These words express ideas and concepts which help to understand the intricate details of the interactions between the political entities and their internal organisations in the Classic Maya Lowlands. In this article I investigate the meaning of emblem glyphs. I suggest that originally they were toponyms but later on they became titles of origin which indicated descendance from a common origin place.En una serie de artículos investigo el uso de varias palabras en las inscripciones mayas de la época Clásica de la Región Occidental que se conectan con lo que nosotros llamamos "política". Estas palabras expresan ideas y conceptos que ayudan a entender los matices de las relaciones entre las entidades políticas de las Tierras Bajas Mayas y su organización interna. En este artículo investigo el significado de los glifos emblema. Propongo que originalmente fueron topónimos y después llegaron a ser títulos de origen que indicaron descendencia común de un lugar original.

Peopling the past: new perspectives on the ancient Maya.

Science.gov (United States)

Robin, C

2001-01-02

The new direction in Maya archaeology is toward achieving a greater understanding of people and their roles and their relations in the past. To answer emerging humanistic questions about ancient people's lives Mayanists are increasingly making use of new and existing scientific methods from archaeology and other disciplines. Maya archaeology is bridging the divide between the humanities and sciences to answer questions about ancient people previously considered beyond the realm of archaeological knowledge.

Delineating genetic relationships among the Maya.

Science.gov (United States)

Ibarra-Rivera, Lisa; Mirabal, Sheyla; Regueiro, Manuela M; Herrera, Rene J

2008-03-01

By 250 AD, the Classic Maya had become the most advanced civilization within the New World, possessing the only well-developed hieroglyphic writing system of the time and an advanced knowledge of mathematics, astronomy and architecture. Though only ruins of the empire remain, 7.5 million Mayan descendants still occupy areas of Mexico, Guatemala, Belize, El Salvador, and Honduras. Although they inhabit distant and distinct territories, speak more than 28 languages, and have been historically divided by warfare and a city-state-like political system, and they share characteristics such as rituals, artistic, architectural motifs that distinguish them as unequivocally Maya. This study was undertaken to determine whether these similarities among Mayan communities mirror genetic affinities or are merely a reflection of their common culture. Four Mayan populations were investigated (i.e., the K'iche and Kakchikel from Guatemala and the Campeche and Yucatan from Mexico) and compared with previously published populations across 15 autosomal STR loci. As a whole, the Maya emerge as a distinct group within Mesoamerica, indicating that they are more similar to each other than to other Mesoamerican groups. The data suggest that although geographic and political boundaries existed among Mayan communities, genetic exchanges between the different Mayan groups have occurred, supporting theories of extensive trading throughout the empire. 2007 Wiley-Liss, Inc.

Survey, Settlement, and Population History at the Ancient Maya Site of Pacbitun, Belize

DEFF Research Database (Denmark)

Healy, Paul F.; Helmke, Christophe G.B.; Awe, Jaime J.

2007-01-01

Survey and excavations of mounds on the outskirts of the site of Pacbitun in western Belize provide insights to the ancient Maya settlement pattern at this medium-sized regional center. This research employed two methods: analysis of structural remains from four separate 1000 m transect surveys...... to have been about 5000-6000 persons. This population estimate is compared with several coeval lowland Maya centers, and found to be reasonable for a medium-sized, Late Classic Maya center....

Language Revitalisation from the Ground Up: Promoting Yucatec Maya on Facebook

Science.gov (United States)

Cru, Josep

2015-01-01

This paper looks at current grassroots efforts to revitalise Yucatec Maya, an indigenous language of Mexico, in social media and more specifically on Facebook. In contrast to the limitations of institutional language promotion, the inclusion of Maya on Facebook shows the possibilities that social networks offer not only for actual use of…

Construction of an Yucatec Maya soil classification and comparison with the WRB framework.

Science.gov (United States)

Bautista, Francisco; Zinck, J Alfred

2010-02-13

Mayas living in southeast Mexico have used soils for millennia and provide thus a good example for understanding soil-culture relationships and for exploring the ways indigenous people name and classify the soils of their territory. This paper shows an attempt to organize the Maya soil knowledge into a soil classification scheme and compares the latter with the World Reference Base for Soil Resources (WRB). Several participative soil surveys were carried out in the period 2000-2009 with the help of bilingual Maya-Spanish-speaking farmers. A multilingual soil database was built with 315 soil profile descriptions. On the basis of the diagnostic soil properties and the soil nomenclature used by Maya farmers, a soil classification scheme with a hierarchic, dichotomous and open structure was constructed, organized in groups and qualifiers in a fashion similar to that of the WRB system. Maya soil properties were used at the same categorical levels as similar diagnostic properties are used in the WRB system. The Maya soil classification (MSC) is a natural system based on key properties, such as relief position, rock types, size and quantity of stones, color of topsoil and subsoil, depth, water dynamics, and plant-supporting processes. The MSC addresses the soil properties of surficial and subsurficial horizons, and uses plant communities as qualifier in some cases. The MSC is more accurate than the WRB for classifying Leptosols.

Adaptations of a Yucatec Maya Multiple-Use Ecological Management Strategy to Ecotourism

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Eduardo García-Frapolli

2008-12-01

Full Text Available Over the last 40 years, the Yucatan Peninsula has experienced the implementation and promotion of development programs that have economically and ecologically shaped this region of Mexico. Nowadays, tourist development has become the principal catalyst of social, economic, and ecological changes in the region. All these programs, which are based on a specialization rationale, have historically clashed with traditional Yucatec Maya management of natural resources. Using participant observation, informal and semi-structured interviews, and life-history interviews, we carried out an assessment of a Yucatec Maya natural resources management system implemented by three indigenous communities located within a natural protected area. The assessment, intended as an examination of the land-use practices and productive strategies currently implemented by households, was framed within an ecological-economic approach to ecosystems appropriation. To examine the influence of tourism on the multiple-use strategy, we contrasted productive activities among households engaged primarily in ecotourism with those more oriented toward traditional agriculture. Results show that households from these communities allocated an annual average of 586 work days to implement a total of 15 activities in five different land-use units, and that those figures vary significantly in accordance with households' productive strategy (agriculture oriented or service oriented. As the region is quickly becoming an important tourist destination and ecotourism is replacing many traditional activities, we discuss the need for a balance between traditional and alternative economic activities that will allow Yucatec Maya communities to diversify their economic options without compromising existing local management practices.

Print Knowledge in Yucatec Maya-Spanish Bilingual Children: An Initial Inquiry

Science.gov (United States)

Bengochea, Alain; Justice, Laura M.; Hijlkema, Maria J.

2017-01-01

This study serves as an initial inquiry regarding the early print knowledge of emergent bilingual preschool-age children living in an Indigenous community in Mexico. In this research, we examine various dimensions of print knowledge with Yucatec Maya-Spanish bilingual children for whom one of their languages (Yucatec Maya) is seldom seen in print…

Representing Mayas : Indigenous Authorities and the Local Politics of Identity in Guatemala

NARCIS (Netherlands)

Rasch, E.D.

2008-01-01

Against the backdrop of emerging indigenous movements in Latin America, the Maya Movement appeared as a political actor in the 1980s, bringing “the Indian Question” to the fore in Guatemalan politics. Rejecting racism and assimilationalist State policies, the Maya Movement seeks to recapture

Economic Stratification Differentiates Home Gardens in the Maya Village of Pomuch, Mexico

NARCIS (Netherlands)

Poot-Pool, W.S.; Wal, van der J.C.; Flores-Guido, S.; Pat-Fernández, J.M.; Esparza-Olguín, L.

2012-01-01

Economic Stratification Differentiates Home Gardens in the Maya Village of Pomuch, Mexico. In this paper, we analyze if economic stratification of peasant families in a Maya village in the Yucatán Peninsula of Mexico influences species composition and structure of home gardens. Our general

An autonomous underwater vehicle "Maya", for monitoring coastal waters, estuaries, rivers and dams

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.A; Navelkar, G.S.; Madhan, R.; Dabholkar, N.A; Prabhudesai, S.P.; Maurya, P.K.; Desa, E.; Afzulpurkar, S.; Suresh, T.; Matondkar, S.G.P.; Mahalunkar, A

This article demonstrates the use of Maya, Autonomous Underwater Vehicle (AUV) for monitoring coastal waters, estuaries, rivers and dams. Maya is a mono hull structure with detachable nose and tail cones. The nose cone is mission specific...

Construction of an Yucatec Maya soil classification and comparison with the WRB framework

Directory of Open Access Journals (Sweden)

Zinck J Alfred

2010-02-01

Full Text Available Abstract Background Mayas living in southeast Mexico have used soils for millennia and provide thus a good example for understanding soil-culture relationships and for exploring the ways indigenous people name and classify the soils of their territory. This paper shows an attempt to organize the Maya soil knowledge into a soil classification scheme and compares the latter with the World Reference Base for Soil Resources (WRB. Methods Several participative soil surveys were carried out in the period 2000-2009 with the help of bilingual Maya-Spanish-speaking farmers. A multilingual soil database was built with 315 soil profile descriptions. Results On the basis of the diagnostic soil properties and the soil nomenclature used by Maya farmers, a soil classification scheme with a hierarchic, dichotomous and open structure was constructed, organized in groups and qualifiers in a fashion similar to that of the WRB system. Maya soil properties were used at the same categorical levels as similar diagnostic properties are used in the WRB system. Conclusions The Maya soil classification (MSC is a natural system based on key properties, such as relief position, rock types, size and quantity of stones, color of topsoil and subsoil, depth, water dynamics, and plant-supporting processes. The MSC addresses the soil properties of surficial and subsurficial horizons, and uses plant communities as qualifier in some cases. The MSC is more accurate than the WRB for classifying Leptosols.

Bioarchaeological investigation of ancient Maya violence and warfare in inland Northwest Yucatan, Mexico.

Science.gov (United States)

Serafin, Stanley; Lope, Carlos Peraza; Uc González, Eunice

2014-05-01

This study investigates evidence of changes and continuities in ancient Maya violence and warfare in inland northwest Yucatan, Mexico from the Middle Preclassic (600-300 BC) to the Postclassic (AD 1050-1542) through bioarchaeological analysis of cranial and projectile trauma. It is hypothesized that the frequency of violence increases before the Classic Maya collapse and remains high during the Postclassic period. It is also hypothesized that the flat, open terrain was conducive to warfare and resulted in higher trauma frequencies than in other parts of the Maya area. Results show that the frequency of cranial trauma decreases before the Classic collapse and increases in the Postclassic, partially matching the expected chronological trends. The frequency of cranial trauma does not differ significantly from other Maya regions but the pattern does: for all periods, males have more healed injuries than females and they are concentrated on the left side of the anterior of the skull. Some injuries appear to be from small points hafted in wooden clubs. In addition, projectile trauma is evident in a scapula with an embedded arrowhead tip, the first such case reported in a Maya skeleton. Overall, these results suggest greater reliance on open combat and less on raids in this region compared with other parts of the Maya area, possibly due to the flat, open terrain, though the identification of perimortem trauma in both women and men indicates surprise raids on settlements were also practiced. Copyright © 2014 Wiley Periodicals, Inc.

Los tablados: Arquitectura vernácula efímera de los pueblos mayas

Directory of Open Access Journals (Sweden)

Aurelio Sánchez Suárez

2015-06-01

Full Text Available La arquitectura vernácula de los mayas de la península de Yucatán, en su representación de la casa maya, es reconocida no solo por el impacto que la cultura maya ha tenido últimamente, sino también por su historia que deviene desde el periodo mesoamericano, durante el cual esta construcción, que continúa vigente como vivienda en la actualidad, fue reproducida en la ornamentación y bóvedas de la arquitectura monumental. Los saberes constructivos, conservados por siglos en la construcción de la casa maya, fueron también empleados para la creación de una nueva estructura llamada "tablado", la que se generó durante el proceso de apropiación de la tauromaquia por parte de los mayas peninsulares, asignándole significados propios de su cosmovisión. El presente trabajo detalla una parte de los resultados del proyecto de investigación que propone una mirada a esta expresión vernácula en los estados de Campeche y Yucatán, en México.

Genomic insights on the ethno-history of the Maya and the 'Ladinos' from Guatemala.

Science.gov (United States)

Söchtig, Jens; Álvarez-Iglesias, Vanesa; Mosquera-Miguel, Ana; Gelabert-Besada, Miguel; Gómez-Carballa, Alberto; Salas, Antonio

2015-02-25

Guatemala is a multiethnic and multilingual country located in Central America. The main population groups separate 'Ladinos' (mixed Native American-African-Spanish), and Native indigenous people of Maya descent. Among the present-day Guatemalan Maya, there are more than 20 different ethnic groups separated by different languages and cultures. Genetic variation of these communities still remains largely unexplored. The principal aim of this study is to explore the genetic variability of the Maya and 'Ladinos' from Guatemala by means of uniparental and ancestry informative markers (AIMs). Analyses of uniparental genetic markers indicate that Maya have a dominant Native American ancestry (mitochondrial DNA [mtDNA]: 100%; Y-chromosome: 94%). 'Ladino', however, show a clear gender-bias as indicated by the large European ancestry observed in the Y-chromosome (75%) compared to the mtDNA (0%). Autosomal polymorphisms (AIMS) also mirror this marked gender-bias: (i) Native American ancestry: 92% for the Maya vs. 55% for the 'Ladino', and (ii) European ancestry: 8% for the Maya vs. 41% for the 'Ladino'. In addition, the impact of the Trans-Atlantic slave trade on the present-day Guatemalan population is very low (and only occurs in the 'Ladino'; mtDNA: 9%; 4%), in part mirroring the fact that Guatemala has a predominant orientation to the Pacific Ocean instead of a Caribbean one. Sequencing of entire Guatemalan mitogenomes has led to improved Native American phylogeny via the addition of new haplogroups that are mainly observed in Mesoamerica and/or the North of South America. The data reveal the existence of a fluid gene flow in the Mesoamerican area and a predominant unidirectional flow towards South America, most likely occurring during the Pre-Classic (1800 BC-200 AD) and the Classic (200-1000 AD) Eras of the Mesoamerican chronology, coinciding with development of the most distinctive and advanced Mesoamerican civilization, the Maya. Phylogenetic features of mtDNA data

Objetual Regime of the Maya during Classic period, a proposal

OpenAIRE

Antonio Jaramillo Arango

2016-01-01

Within the academic archaeology of the 20th Century, objects were only considered as sources for understanding human action. Based on recent theoretic anthropological proposals, this paper proposes a recursive archaeology, that is, to include the Classic Maya concepts as part of our analysis in order to understand things as truly protagonists of social relationships. In the Maya area, objects have different ways of being in the world which have been identified by the archeology of the Classic...

Los tablados: Arquitectura vernácula efímera de los pueblos mayas

OpenAIRE

Aurelio Sánchez Suárez

2015-01-01

La arquitectura vernácula de los mayas de la península de Yucatán, en su representación de la casa maya, es reconocida no solo por el impacto que la cultura maya ha tenido últimamente, sino también por su historia que deviene desde el periodo mesoamericano, durante el cual esta construcción, que continúa vigente como vivienda en la actualidad, fue reproducida en la ornamentación y bóvedas de la arquitectura monumental. Los saberes constructivos, conservados por siglos en la construcción de la...

Finds in Belize document Late Classic Maya salt making and canoe transport

Science.gov (United States)

McKillop, Heather

2005-01-01

How did people in preIndustrial ancient civilizations produce and distribute bulk items, such as salt, needed for everyday use by their large urban populations? This report focuses on the ancient Maya who obtained quantities of salt at cities in the interior of the Yucatan peninsula of Mexico, Belize, and Guatemala in an area where salt is scarce. I report the discovery of 41 Late Classic Maya saltworks (anno Domini 600–900) in Punta Ycacos Lagoon on the south coast of Belize, including one with the first-known ancient Maya canoe paddle. The discoveries add important empirical information for evaluating the extent of surplus salt production and river transport during the height of Late Classic civilization in the southern Maya lowlands. The discovery of the saltworks indicates that there was extensive production and distribution of goods and resources outside the cities in the interior of the Yucatan. The discovery of a wooden canoe paddle from one of the Punta Ycacos saltworks, Ka'k' Naab', ties the production of salt to its inland transport by rivers and documents the importance of canoe trade between the coast and the interior during the Late Classic. Archaeological discovery of multiple saltworks on the Belizean coast represents surplus production of salt destined largely for the inland Peten Maya during their Late Classic peak, underscoring the importance of non-state-controlled workshop production in preIndustrial societies. PMID:15809426

Finish your film! tips and tricks for making an animated short in Maya

CERN Document Server

Roy, Kenny

2014-01-01

Finish Your Film! Tips and Tricks for Making an Animated Short in Maya is a first-of-its-kind book that walks the reader step-by-step through the actual production processes of creating a 3D Short film with Maya. Other books focus solely on the creative decisions of 3D Animation and broadly cover the multiple phases of animation production with no real applicable methods for readers to employ. This book shows you how to successfully manage the entire Maya animation pipeline. This book blends together valuable technical tips on film production and real-world shortcuts in a step-by-step approach

La legitimación de la realeza entre mayas del Preclásico Tardío. Los mascarones de El Tigre, Campeche Legitimizing royalty among Late Preclassic Maya. The masks from El Tigre-Campeche

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Ernesto Vargas Pacheco

2010-01-01

Full Text Available En el arte monumental del periodo Clásico maya la imagen del señor ocupaba el sitio principal y todas las demás imágenes un lugar secundario. Con este trabajo se quiere demostrar que los soberanos mayas ya en el Preclásico Tardío, o desde antes, usaron la arquitectura para reproducir la topografía del universo y se sirvieron de los mascarones para transmitir la condición divina de sus antepasados, de sus dioses y la suya propia. En El Tigre, Campeche, se han explorado varios mascarones de estuco del Preclásico Tardío, que representan rostros humanos, los cuales bien podrían identificarse como ancestros: antepasados de gobernantes que pretenden divinizarlos para así legitimizar la realeza maya.The images of Maya dignitaries take the most important places in monumental art during Classic period, and all other representations occupy a secondary position in that context. This paper pretends to demonstrate that Maya kings tried to duplicate their conception of the Universe on civic architecture since Preclassic period, or even before; they used huge mask representations to transmit the sacred condition of their ancestors, their gods and their selves. At El Tigre site, in Campeche, have been explored several stucco masks of Late Preclassic date, showing human faces that may represent ancestors of the kings who tried to deify them in order to legitimate Maya royalty.

Perspectives on Ancient Maya Rural Complexity

OpenAIRE

Iannone, Gyles; Connell, Samuel V

2003-01-01

Settlement archaeology in the Maya area has focused much of its attention on the polar extremes of the settlement continuum. As a result of this urban/rural bias, a whole range of complex rural settlements remain under-explored. The chapters in this volume highlight the variable quality of these "middle level settlements".

What We Think We Know About Maya Mathematics and Astronomy

Science.gov (United States)

Van Stone, M.

2016-01-01

In most cultures, mathematics and astronomy are obscure and arcane. Not so to the ancient Maya. Despite what we consider technological “deficiencies”—they lacked both metal tools and the wheel—their public inscriptions paid uniquely sophisticated attention to these sciences. At any given monument, fully half the text is devoted to situating events in time, particularly specifying the precise number of days between events, whether historical or mythological. Often these intervals have numerological significance, and many are precise multiples of the periodicities of heavenly bodies. The Maya apparently were fully aware of the exact length of the tropical year, the sidereal year, the cycles of Venus, and eclipses; and there is evidence that they even celebrated events reflecting the 26,000-year precession cycle. However, Maya illuminati had an agenda quite alien to our way of thinking. Clues to their knowledge are arcane, rare, and often difficult for us to recognize with eyes clouded by our modern worldview. The body of work left to us consists of just a few tantalizing sherds of a once-rich and diverse astromythological tradition. Moreover, there was no single pan-Mayan mythos. An astronomical alignment seen repeatedly in one city will be completely absent in others. Each city-state emphasized specific and often unique features, and they often contradict one another. But we soldier on. The diversity we find so frustrating is simply the fine structure of their worldview. Intellectual historians have for too long been, like Procrustes, trying to force all Maya science and religion into a single universal straitjacket.

Is the onset of the 6th century 'dark age' in Maya history related to explosive volcanism?

Science.gov (United States)

Nooren, Kees; Hoek, Wim Z.; Van der Plicht, Hans; Sigl, Michael; Galop, Didier; Torrescano-Valle, Nuria; Islebe, Gerald; Huizinga, Annika; Winkels, Tim; Middelkoop, Hans; Van Bergen, Manfred

2016-04-01

Maya societies in Southern Mexico, Guatemala and Belize experienced a 'dark age' during the second half of the 6th century. This period, also known as the 'Maya Hiatus', is characterized by cultural downturn, political instability and abandonment of many sites in the Central Maya Lowlands. Many theories have been postulated to explain the occurrence of this 'dark age' in Maya history. A possible key role of a large volcanic eruption in the onset of this 'dark age' will be discussed. Volcanic deposits recovered from the sedimentary archive of lake Tuspán and the Usumacinta-Grijalva delta were studied in detail and the combination of multiple dating techniques allowed the reconstruction of the timing of a large 6th century eruption. Volcanic glass shards were fingerprinted to indicate the source volcano and high resolution pollen records were constructed to indicate the environmental impact of the eruption. Results are compared with available archaeological data and causality with the disruption of Maya civilization will be evaluated.

Geochemical of clay formations : study of Spanish clay REFERENCE

International Nuclear Information System (INIS)

Turrero, M. J.; Pena, J.

2003-01-01

Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

Radar mapping, archaeology, and ancient land use in the Maya lowlands

Science.gov (United States)

Adams, R. E. W.; Brown, W. E., Jr.; Culbert, T. P.

1981-01-01

Data from the use of synthetic aperture radar in aerial survey of the southern Maya lowlands suggest the presence of very large areas drained by ancient canals for the purpose of intensive cultivation. Preliminary ground checks in several very limited areas confirm the existence of canals and raised fields. Excavations and ground surveys by several scholars provide valuable comparative information. Taken together, the new data suggest that Late Classic period Maya civilization was firmly grounded in large-scale and intensive cultivation of swampy zones.

Deep data science to prevent and treat growth faltering in Maya children

OpenAIRE

Varela-Silva, M I; Bogin, B; Sobral, J A G; Dickinson, F; Monserrat-Revillo, S

2016-01-01

The Maya people are descended from the indigenous inhabitants of southern Mexico, Guatemala and adjacent regions of Central America. In Guatemala, 50% of infants and children are stunted (very low height-for-age), and some rural Maya regions have >70% children stunted. A large, longitudinal, intergenerational database was created to (1) provide deep data to prevent and treat somatic growth faltering and impaired neurocognitive development, (2) detect key dependencies and predictive relations ...

The Source of Volcanic Ash in Late Classic Maya Pottery at El Pilar, Belize

Science.gov (United States)

Catlin, B. L.; Ford, A.; Spera, F. J.

2007-12-01

order to test the effects of pot firing on glass compositional changes, experiments were conducted in which high silica volcanic glass was fired with clay according to heating schedules used by Maya potters. Two important changes are that Na is rapidly lost preferentially to K and that the Si/Ca ratio decreases due to Ca diffusion from matrix into glass during firing. One expects that ratios of the refractory trace elements such as La/Yb and Zr/Hf are less susceptible to modification. Further experiments of trace element mobility during firing are underway.

Personhood in Maya Art : a theoretical perspective

NARCIS (Netherlands)

Osorio, Laura Ann

2015-01-01

In contrast to a traditional ethno-archaeological approach, in which contemporary communities are mined for information that can be applied to the past, this study considers that the interpretation of Maya material culture belongs to the people whose identity has been formed within the natural and

The importance of considering gestures in the study of current spoken Yucatec Maya.

Directory of Open Access Journals (Sweden)

Olivier Le Guen

2018-02-01

Full Text Available For centuries, linguistic description has been somehow limited because it was not possible to record audio and video. For this reason, the intrinsic multimodal nature of human language has been left out, putting aside various types of information both prosodic and visual. This work analyzes the ways in which gestures complement speech, taking into account several levels of analysis: pragmatic, semantic and syntactic; but also how some gestures can be considered linguistic signs. In order to exemplify the argumentation, I will consider the Yucatec Maya language using examples of spontaneous productions. Although certain processes presented in this work are specific to Yucatec Maya, most can be found in various languages. This paper first presents a definition of language, speech and gestures, and how one can study the way in which speech and gestures are integrated in a composite utterance. Subsequently, I analyze examples of different types of gestures in various areas of communication in Yucatec Maya, such as deictic gestures, the use of expressive gestures, metaphors and the integration of gestures at the pragmatic level. Finally, I explain how gestures can become linguistic signs in Yucatec Maya.

77 FR 53959 - Culturally Significant Object Imported for Exhibition Determinations: “Dancing Into Dreams, Maya...

Science.gov (United States)

2012-09-04

... DEPARTMENT OF STATE [Public Notice 8009] Culturally Significant Object Imported for Exhibition Determinations: ``Dancing Into Dreams, Maya Vases From the IK'Kingdom'' SUMMARY: Notice is hereby given of the... exhibition ``Dancing Into Dreams, Maya Vases from the IK'Kingdom,'' imported from abroad for temporary...

The Maya Tropical Forest: Cascading Human impacts from Hillslopes to Floodplains

Science.gov (United States)

Beach, Timothy; Luzzadder-Beach, Sheryl; Doyle, Colin; Krause, Samantha; Brokaw, Nicholas; Yaeger, Jason

2016-04-01

We review the long-term human impact on fluvial systems in the Maya tropical forest region. Although most of this karstic region is drained by groundwater, the southern and coastal margins have several river systems that drain volcanic and metamorphic as well as sedimentary terrains. Some positive environmental impacts of Maya Civilization were the long-term impacts of both landesque capital, like wetland field systems, and other land uses that have enriched many soils. Some negative impacts included stripped soils and eutrophic rivers, both playing out again today with recent deforestation and intensive agriculture. We review trends in the region's fluvial systems, present new evidence on beneficial and detrimental impacts of Maya civilization, and present a new study using LiDAR mapping of fluvial geomorphology of the Belize River. Our new field research comes from the transboundary Rio Bravo watershed of Belize and Guatemala near the border with Mexico. This watershed today is mainly a well preserved tropical forest but from 3,000 to 1000 years ago was partly deforested by Maya cities, farms, roads, fires, and fields. We present studies of soils and sediment movement along slopes, floodplains, and water quality impacts of high dissolved loads of sulfate and calcium. We use AMS dates and soil stratigraphy to date slope and floodplain flux, and we use multiple proxies like pollen and carbon isotopes to reconstruct ancient land use. Aggradation in the floodplain and colluvial deposits began by at least 3,000 years ago and continued until 1100 years ago in several study sites. Some Classic period sites with peak human population and land use intensity experienced less soil erosion, perhaps due to soil conservation, post urban construction, and source reduction. Additional evidence suggests that ancient terraced sites and colluvial slopes that gained upslope sediment and soil nutrients from ancient Maya erosion had greater biodiversity. Lastly, we map fluvial

Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

Energy Technology Data Exchange (ETDEWEB)

Randall T. Cygan

2007-06-01

“Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

Does the Maya Forest Need More Roads?

DEFF Research Database (Denmark)

Conde, Dalia Amor; Ramos, Victor Hugo; Burgués, Irene

levels of poverty found in this area. But more and better roads usually bring more people and expand farms. Decision-makers are therefore confronted with a seeming conflict between conservation and development goals. Would new roads be bad or good for the Maya Forest region? To help answer that question...

Physico-chemical analysis of the bricks used in the construction of the pyramid of the archaeological zone of Comalcalco, Tabasco; Analisis fisico-quimico de los ladrillos usados en la construccion de la piramide de la zona arqueologica de Comalcalco, Tabasco

Energy Technology Data Exchange (ETDEWEB)

Custodio G, E.; Acosta A, M. [Universidad Juarez Autonoma de Tabasco, 86680 Tabasco (Mexico); Sebastian, P.J. [CIE-UNAM, 62580 Temixco, Morelos (Mexico); Trevino P, C.G. [INAOE, 72000 Puebla (Mexico); Mendoza A, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2005-07-01

The presence of clay as human hand craft is first observed in Mexico on westernmost city of the Maya region, known as Comalcalco, therefore Comalcalco comes from the nahuatl: Comali- cali-co or 'Brick house'. This city that flourish on the classical period between the centuries I b.C. to IX a.C, was contemporary to Palenque and Yaxchilan among others. Due to the lack of rocks for construction and abundance of clay in the region, the Mayas used the clay as fired clay bricks to build their palaces and ceremonial temples. On this work, we present a study using Sem, EDS and XRD on the fired clay bricks used on these constructions to induce de type clay used and temperature of firing. (Author)

Physico-chemical analysis of the bricks used in the construction of the pyramid of the archaeological zone of Comalcalco, Tabasco

International Nuclear Information System (INIS)

Custodio G, E.; Acosta A, M.; Sebastian, P.J.; Trevino P, C.G.; Mendoza A, D.

2005-01-01

The presence of clay as human hand craft is first observed in Mexico on westernmost city of the Maya region, known as Comalcalco, therefore Comalcalco comes from the nahuatl: Comali- cali-co or 'Brick house'. This city that flourish on the classical period between the centuries I b.C. to IX a.C, was contemporary to Palenque and Yaxchilan among others. Due to the lack of rocks for construction and abundance of clay in the region, the Mayas used the clay as fired clay bricks to build their palaces and ceremonial temples. On this work, we present a study using Sem, EDS and XRD on the fired clay bricks used on these constructions to induce de type clay used and temperature of firing. (Author)

Miniature sonar for obstacle detection on samll AUV Maya

Digital Repository Service at National Institute of Oceanography (India)

Afzulpurkar, S.; Desa, E.; Navelkar, G.; Mascarenhas, A.A.M.Q.; Maurya, P.K.; Martins, H.; Madhan, R.; Prabhudesai, S.; Pinto, R.; Marchon, N.

that are communicated to the mission computer of Maya which uses a distributed CAN network architecture for internal subsystem communications. The mission computer can use this new heading data for navigation accordingly....

Analysis of obsidian from moho cay, belize: new evidence on classic maya trade routes.

Science.gov (United States)

Healy, P F; McKillop, H I; Walsh, B

1984-07-27

Trace element analysis of obsidian artifacts from Moho Cay, Belize, reveals that the obsidian derives primarily from the El Chayal outcrop in highland Guatemala and not from the Ixtepeque source. This is contrary to the widely accepted obsidian trade route model for Classic Maya civilization and suggests that Classic Maya obsidian trade was a more complex economic phenomenon than has been recognized.

Chemical Tools of Octopus maya during Crab Predation Are Also Active on Conspecifics.

Science.gov (United States)

Pech-Puch, Dawrin; Cruz-López, Honorio; Canche-Ek, Cindy; Campos-Espinosa, Gabriela; García, Elpidio; Mascaro, Maite; Rosas, Carlos; Chávez-Velasco, Daniel; Rodríguez-Morales, Sergio

2016-01-01

Octopus maya is a major socio-economic resource from the Yucatán Peninsula in Mexico. In this study we report for the first time the chemical composition of the saliva of O. maya and its effect on natural prey, i.e. the blue crab (Callinectes sapidus), the crown conch snail (Melongena corona bispinosa), as well as conspecifics. Salivary posterior glands were collected from octopus caught by local fishers and extracted with water; this extract paralyzed and predigested crabs when it was injected into the third pereiopod. The water extract was fractionated by membrane ultrafiltration with a molecular weight cut-off of 3 kDa leading to a metabolic phase (>3 kDa) and a neurotoxic fraction (octopus saliva might be used among conspecifics for defense and for reduction of competition. Bioguided separation of the neurotoxic fraction by chromatography led to a paralysis fraction and a relaxing fraction. The paralyzing activity of the saliva was exerted by amino acids, while the relaxing activity was due to the presence of serotonin. Prey-handling studies revealed that O. maya punctures the eye or arthrodial membrane when predating blue crabs and uses the radula to bore through crown conch shells; these differing strategies may help O. maya to reduce the time needed to handle its prey.

Egyptians, Maya, Minoans. Learning Works Enrichment Series.

Science.gov (United States)

Matthies, Susanna

The activities in this instructional resource book are designed to be used by gifted 4-8th grade students as independent research guides or in guided or cooperative learning environments. The activities are organized in three sections which focus the ancient civilizations of Egypt, Maya, and Minoa. The activities presented encourage development of…

An assessment of dioxin levels in processed ball clay from the United States

Energy Technology Data Exchange (ETDEWEB)

Ferrario, J.; Byrne, C. [USEPA, Stennis Space Ctr. Mississippi (United States); Schaum, J. [USEPA, Washington, DC (United States)

2004-09-15

Introduction The presence of dioxin-like compounds in ball clay was discovered in 1996 as a result of an investigation to determine the sources of elevated levels of dioxin found in two chicken fat samples from a national survey of poultry. The investigation indicated that soybean meal added to chicken feed was the source of dioxin contamination. Further investigation showed that the dioxin contamination came from the mixing of a natural clay known as ''ball clay'' with the soybean meal as an anti-caking agent. The FDA subsequently discontinued the use of contaminated ball clay as an anti-caking agent in animal feeds. The source of the dioxins found in ball clay has yet to be established. A comparison of the characteristic dioxin profile found in ball clay to those of known anthropogenic sources from the U.S.EPA Source Inventory has been undertaken, and none of those examined match the features found in the clays. These characteristic features together with the fact that the geologic formations in which the clays are found are ancient suggest a natural origin for the dioxins. The plasticity of ball clays makes them an important commercial resource for a variety of commercial uses. The percentage of commercial uses of ball clay in 2000 included: 29% for floor and wall tile, 24% for sanitary ware, 10% pottery, and 37% for other industrial and commercial uses. The total mining of ball clay in the U.S. for 2003 was 1.12 million metric tons. EPA is examining the potential for the environmental release of dioxins from the processing/use of ball clays and evaluating potential exposure pathways. Part of this overall effort and the subject of this study includes the analysis of dioxin levels found in commercially available ball clays commonly used in ceramic art studios.

Clastic compaction unit classification based on clay content and integrated compaction recovery using well and seismic data

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Zhong Hong

2016-11-01

Full Text Available Abstract Compaction correction is a key part of paleo-geomorphic recovery methods. Yet, the influence of lithology on the porosity evolution is not usually taken into account. Present methods merely classify the lithologies as sandstone and mudstone to undertake separate porosity-depth compaction modeling. However, using just two lithologies is an oversimplification that cannot represent the compaction history. In such schemes, the precision of the compaction recovery is inadequate. To improve the precision of compaction recovery, a depth compaction model has been proposed that involves both porosity and clay content. A clastic lithological compaction unit classification method, based on clay content, has been designed to identify lithological boundaries and establish sets of compaction units. Also, on the basis of the clastic compaction unit classification, two methods of compaction recovery that integrate well and seismic data are employed to extrapolate well-based compaction information outward along seismic lines and recover the paleo-topography of the clastic strata in the region. The examples presented here show that a better understanding of paleo-geomorphology can be gained by applying the proposed compaction recovery technology.

MaritimeMaya2011: The Costa Escondida Project: Exploring the Hidden World of the Maritime Maya on the Yucatan Peninsula between 20110509 and 20110531

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The northeast tip of the Yucatan Peninsula is a largely unexplored coastline where ancient Maya traders traveled in massive dugout canoes filled with goods from...

THE MAYA INDEX ANALYSIS ON DENGUE PATIENT HOUSEHOLD IN BANJAR CITY, 2012

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Pandji Wibawa Dhewantara

2015-07-01

Full Text Available Salah satu faktor risiko kejadian DBD di antaranya adalah ketersediaan kontainer tempat perkembangbiakan vektor. Tahun2012 dilakukan survei observasional analitik dengan pendekatan potong lintang pada 100 rumah penderita DBD di KotaBanjar. Tujuan penelitian untuk mengetahui tingkat risiko penularan DBD melalui pendekatan analisis Maya Index. Datayang dikumpulkan meliputi jenis, jumlah kontainer, dan jumlah kontainer mengandung larva Aedes sp. Kontainer yangditemukan dikategorikan menjadi Controllable Container dan Disposable Container untuk mengetahui Breeding Risk Index(BRI dan Hygene Risk Index (HRI. Analisis deskriptif digunakan untuk mengetahui proporsi jumlah dan jenis kontainer.Maya index diperoleh dari hasil pengkategorian rasio BRI dan HRI. Container Index dan Breteau Index dihitung untukmengetahui kepadatan larva. Hasil pengamatan ditemukan sebanyak 915 kontainer yang terdiri dari jenis controllablecontainers (93% dan disposable containers (7%. Jenis kontainer yang dominan adalah tempayan tanah liat (15,52%, bakair (14,35%, pot bunga (48,47%, dan penampung air pada dispenser (7%. Larva Aedes sp. banyak ditemukan pada bak air(48,57% dan penampung air pada dispenser (22,86%. Sementara, botol bekas (35,3% dan kaleng bekas (26,1%merupakan jenis disposable container yang paling banyak ditemukan. Analisis menunjukkan sebagian besar rumahberkategori BRI tinggi (93% dan HRI rendah (92%. Berdasarkan Maya Index, rumah penderita termasuk dalam kategoririsiko sedang (97% dengan CI dan BI masing-masing sebesar 3,85% dan 35. Studi ini menyimpulkan bahwa sebagian besarrumah penderita masih memiliki potensi penularan infeksi virus Dengue.Kata kunci: DBD, risiko perkembangbiakan larva, kontainer, indeks risiko kebersihan, Maya Index

Construction of an Yucatec Maya soil classification and comparison with the WRB framework

OpenAIRE

Zinck J Alfred; Bautista Francisco

2010-01-01

Abstract Background Mayas living in southeast Mexico have used soils for millennia and provide thus a good example for understanding soil-culture relationships and for exploring the ways indigenous people name and classify the soils of their territory. This paper shows an attempt to organize the Maya soil knowledge into a soil classification scheme and compares the latter with the World Reference Base for Soil Resources (WRB). Methods Several participative soil surveys were carried out in the...

Guatemala paleoseismicity: from Late Classic Maya collapse to recent fault creep

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Brocard, Gilles; Anselmetti, Flavio S.; Teyssier, Christian

2016-11-01

We combine ‘on-fault’ trench observations of slip on the Polochic fault (North America-Caribbean plate boundary) with a 1200 years-long ‘near-fault’ record of seismo-turbidite generation in a lake located within 2 km of the fault. The lake record indicates that, over the past 12 centuries, 10 earthquakes reaching ground-shaking intensities ≥ VI generated seismo-turbidites in the lake. Seismic activity was highly unevenly distributed over time and noticeably includes a cluster of earthquakes spread over a century at the end of the Classic Maya period. This cluster may have contributed to the piecemeal collapse of the Classic Maya civilization in this wet, mountainous southern part of the Maya realm. On-fault observations within 7 km of the lake show that soils formed between 1665 and 1813 CE were displaced by the Polochic fault during a long period of seismic quiescence, from 1450 to 1976 CE. Displacement on the Polochic fault during at least the last 480 years included a component of slip that was aseismic, or associated with very light seismicity (magnitude 1 ky) punctuated by destructive earthquake clusters.

Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region

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Kamenov, George D.; Gilli, Adrian; Hodell, David A.; Emery, Kitty F.; Brenner, Mark; Krigbaum, John

2016-01-01

We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (87Sr/86Sr) and oxygen (δ18O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region. PMID:27806065

Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region.

Science.gov (United States)

Sharpe, Ashley E; Kamenov, George D; Gilli, Adrian; Hodell, David A; Emery, Kitty F; Brenner, Mark; Krigbaum, John

2016-01-01

We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (87Sr/86Sr) and oxygen (δ18O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region.

Politics in the Western Maya Region (I: Ajawil/Ajawlel and Ch'e'n

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Péter Bíró

2011-01-01

Full Text Available In a series of articles I reflect on the use of various expressions which are connected to what we call the political in the inscriptions of the Classic Maya Western Region. These words express concepts which help to understand the intricate details of the interactions between the political entities and their internal organisations in the Classic Maya Lowlands. Words such as 7ajawil, 7ajawlel, the kennings built on the base of ch'e7n (cave, pond, the emblem glyphs and titles will be examined in light of what they tell us about the functioning of the political organisation of the Classic Period in a constrained region.En una serie de artículos como éste investigo el uso de varias palabras en las inscripciones mayas de la época Clásica de la Región Occidental vinculadas con lo que nosotros llamamos "política". Estas palabras expresan conceptos que ayudan a entender los matices de las relaciones entre las entidades políticas de las Tierras Bajas Mayas y su organización interna. Términos como ajaw'ü I ajawlel, los difrasismos con base ch'e'n (cueva, pozo, los glifos emblemas y los títulos serán examinados tomando en cuenta la información que nos proporcionan sobre el funcionamiento de la organización política de la época Clásica en una región restringida.

Will America Fall Apart Like the Maya? Grade 7 Lesson. Schools of California Online Resources for Education (SCORE): Connecting California's Classrooms to the World.

Science.gov (United States)

McDonald, David

If a civilization as powerful and technologically advanced during its time as the Maya could disappear, can the same tragic outcome befall the United States? In this lesson, students work in teams to research the ancient Mayan civilization, specifically the circumstances of its demise. Student teams prepare a report of their findings and recommend…

Sustaining Rainforest Plants, People and Global Health: A Model for Learning from Traditions in Holistic Health Promotion and Community Based Conservation as Implemented by Q’eqchi’ Maya Healers, Maya Mountains, Belize

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Pablo Sanchez-Vindas

2010-10-01

Full Text Available The present work showcases a model for holistic, sustainable healthcare in indigenous communities worldwide through the implementation of traditional healing practices. The implementation of this model promotes public health and community wellness while addressing crucially important themes such as in situ and ex situ conservation of medicinal plant resources and associated biodiversity, generational transmission of knowledge, and the preservation of biological and cultural diversity for future generations. Being envisaged and implemented by Q’eqchi’ Maya traditional healers of the southern Maya Mountains, Belize, this model can be replicated in other communities worldwide. A ethnobotany study in collaboration with these healers led to collection of 102 medicinal species from Itzama, their traditional healing cultural center and medicinal garden. Of these 102 species, 40 of prior reported 106 consensus study plants were present in the garden. There were 62 plants not previously reported growing in the garden as well. A general comparison of these plants was also made in relation to species reported in TRAMIL network, Caribbean Herbal Pharmacopoeia (CHP, the largest regional medicinal pharmacopoeia. A relative few species reported here were found in the CHP. However, the majority of the CHP plants are common in Belize and many are used by the nearby Mopan and Yucatec Maya. Since these 102 species are relied upon heavily in local primary healthcare, this Q’eqchi’ Maya medicinal garden represents possibilities toward novel sustainable, culturally relative holistic health promotion and community based conservation practices.

A configuração narrativa em idioma maya q'eqchi de Guatemala

OpenAIRE

Bol, Oscar René Saquil

2006-01-01

Guatemala é um país que tem um tecido social composto por diferentes culturas (Maya, Xinca, Garifuna y Ladina). Entre elas o Q'eqchi' como idioma e cultura maya, sobre o qual se desenvolve esta investigação, no campo das ciências da linguagem, adotando os aportes da linguística textual. Neste processo participaram mestres (professores) que trabalham em cinco escolas de Xch'ool Ixim, eles recolheram algumas narrações que se utilizam para a trasmissão de determinados ensinamentos e emoções, ...

Perlindungan Merek Terdaftar Dari Kejahatan Dunia Maya Melalui Pembatasan Pendaftaran Nama Domain

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Setia Dharma

2015-05-01

Full Text Available Abstract: The Protection of Registered Trademark of Cyber Crime Through The Restriction of The Domain Name Registration. The progress of science and technology has implications for the progress of the current trading method. It is not only done conventionally but also carried out through cyberspace. Trading in the virtual world requires the use of a domain name (cyber squatting as a differentiator between one company with other companies. Law No. 11 Year 2008 on Information and Electronic Transactions regulate the use of domain names and emphasize the element of good faith in the implementation. In practice, there is a breach of the domain name registration is a crime which is the trademark or name that has a commercial value. This paper is going to examine aspects of protection-registered trademark of cyber crime through the restriction of the domain name registration and implementation of good faith. Abstrak: Perlindungan Merek Terdaftar Dari Kejahatan Dunia Maya Melalui Pembatasan Pendaftaran Nama Domain. Kemajuan ilmu dan teknologi membawa implikasi pada kemajuan metode perdagangan yang saat ini bukan hanya dilakukan secara konvensional, namun juga dilakukan melalui dunia maya. Perdagangan dalam dunia maya mensyaratkan penggunaan nama domain (cyber squatting sebagai pembeda antara satu perusahaan dengan perusahaan yang lainnya. Undang-Undang No. 11 Tahun 2008 Tentang Informasi dan Transaksi elektronik mengatur penggunaan nama domain tersebut dan menekankan unsur iktikad baik dalam pelaksanaannya. Prakteknya, terdapat pelanggaran nama domain tersebut yang merupakan merupakan kejahatan pendaftaran merek dagang atau nama yang memiliki nilai komersial. Tulisan ini hendak mengkaji aspek perlindungan merek terdaftar dari kejahatan dunia maya melalui pembatasan pendaftaran nama domain dan pelaksanaan iktikad baik. DOI: 10.15408/jch.v1i2.1463

Effect of type of binder on growth, digestibility, and energetic balance of Octopus maya

OpenAIRE

Rosas, C; Tut, J; Baeza, J; Sanchez, A; Sosa, V; Pascual, C; Arena, L; Domingues, P; Cuzon, Gerard

2008-01-01

The present study was designed to test the effects of type of binder on growth, nutritional physiology, total apparent digestibility, and some elements of the energetic balance of early O. maya juveniles. Two experiments were performed. One was aimed at evaluating the effect of type of binder on growth, nutritional physiology, and energetic balance and the other at knowing the effect of the binder on total apparent digestibility of O. maya. Binder type affected growth and survival of early O....

A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

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Graham Edward

2006-04-01

Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

a Review of Late Holocene Fluvial Systems in the Karst Maya Lowlands with Focus on the Rio Bravo, Belize

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Beach, T.; Luzzadder-Beach, S.; Krause, S.; Doyle, C.

2015-12-01

The Maya Lowlands is mostly an internally draining karst region with about 400 m of regional relief. Fluvial and fluviokarst systems drain the edges of this landscape either from low limestone uplands or igneous and metamorphic complexes. Thus far most fluvial research has focused around archaeology projects, and here we review the extant research conducted across the region and new research on the transboundary Rio Bravo watershed of Belize and Guatemala. The Rio Bravo drains a largely old growth tropical forest today, but was partly deforested around ancient Maya cities and farms from 3,000 to 1000 BP. Several studies estimate that 30 to 40 percent of forest survived through the Maya period. Work here has focused on soils and sediment movement along slope catenas, in floodplain sites, and on contributions from groundwater with high dissolved loads of sulfate and calcium. We review radiocarbon dates and present new dates and soil stratigraphy from these sequences to date slope and floodplain movement, and we estimate ancient land use from carbon isotopic and pollen evidence. Aggradation in this watershed occurred by flooding, gypsum precipitation, upland erosion, and ancient Maya canal building and filling for wetland farming. Soil erosion and aggradation started at least by 3,000 BP and continued through the ancient Maya period, though reduced locally by soil conservation, post urban construction, and source reduction, especially in Maya Classic period from 1700 to 1000 BP.

"Cuando alguien habla la Maya se nota que son pobres": Narrativas de identidad de los mayas yucatecos en torno a la radiodifusora indigenista La voz de los mayas, XEPET

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Inés Cornejo Portugal

2010-06-01

Full Text Available En este trabajo se examinan las narrativas de identidad de los receptores culturales de la radiodifusora indigenista “La Voz de los Mayas, Xepet”, respecto de su relación con la oferta radiofónica de esta emisora ubicada en la cabecera municipal de Peto, al sur de Yucatán, México. El propósito es, por un lado, sistematizar, desde el análisis argumentativo, el uso, estructura y estrategias argumentativas de los maya hablantes radioescuchas de Xepet (bilingües o monolingües en torno a la oferta cultural de la misma, así como a la presencia cotidiana de esta emisora en su mundo de vida; y, por otro, reflexionar acerca de la radio indigenista en México como un recurso que podría contribuir a la “cultura de paz”.“U chíikul u t’aan maayao’ob” o “La voz de los mayas”, salió al aire el 29 de noviembre de 1982, en la frecuencia de los 740 khz de AM y fue reubicada al 730 en enero de 2001. Su área de cobertura abarca unos 100 km a la redonda, alcanzando cerca de mil comunidades de la península y parte de Quintana Roo, con una audiencia potencial de 500 mil personas. Su programación incluye géneros musicales y no musicales, compuestos estos últimos por programas informativos, de difusión cultural, servicio e infantiles. Xepet ha sido una de las radiodifusoras pioneras del sistema indigenista promovido por el Estado mexicano desde 1979, modelo que habría de extenderse en las más de veinte emisoras que aparecieron después. Hoy en día, la crítica respecto de la función, contenidos y operación de estas emisoras “oficiales” o “voceras del Gobierno” permanence, debido a que tanto la práctica indigenista como su experiencia radiofónica parecieran estar rebasadas por las demandas de los pueblos indios que reivindican su derecho a la libre determinación y a la autonomía, así como a la propiedad y gestión de sus propios medios de comunicación. Lo anterior reitera la necesidad de una propuesta radiof

Daily life of the ancient Maya recorded on murals at Calakmul, Mexico

Science.gov (United States)

Carrasco Vargas, Ramón; López, Verónica A. Vázquez; Martin, Simon

2009-01-01

Research into ancient societies frequently faces a major challenge in accessing the lives of those who made up the majority of their populations, since the available evidence so often concerns only the ruling elite. Our excavations at the ancient Maya site of Calakmul, Mexico, have uncovered a “painted pyramid:” a structure decorated with murals depicting scenes of its inhabitants giving, receiving, and consuming diverse foods, as well as displaying and transporting other goods. Many are accompanied by hieroglyphic captions that describe the participants, and include spellings of key subsistence items. Collectively, they offer insights into the social mechanisms by which goods were circulated within major Maya centers. PMID:19901331

Human Migration and Agricultural Expansion: An Impending Threat to the Maya Biosphere Reserve

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Sader, Steven; Reining, Conard; Sever, Thomas L.; Soza, Carlos

1997-01-01

Evidence is presented of the current threats to the Maya Biosphere Reserve in northern Guatemala as derived through time-series Landsat Thematic Mapper observations and analysis. Estimates of deforestation rates and trends are examined for different management units within the reserve and buffer zones. The satellite imagery was used to quantify and monitor rates, patterns, and trends of forest clearing during a time period corresponding to new road construction and significant human migration into the newly accessible forest region. Satellite imagery is appropriate technology in a vast and remote tropical region where aerial photography and extensive field-based methods are not cost-effective and current, timely data is essential for establishing conservation priorities.

Kax and kol: Collapse and resilience in lowland Maya civilization

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Dunning, Nicholas P.; Beach, Timothy P.; Luzzadder-Beach, Sheryl

2012-01-01

Episodes of population loss and cultural change, including the famous Classic Collapse, punctuated the long course of Maya civilization. In many cases, these downturns in the fortunes of individual sites and entire regions included significant environmental components such as droughts or anthropogenic environmental degradation. Some afflicted areas remained depopulated for long periods, whereas others recovered more quickly. We examine the dynamics of growth and decline in several areas in the Maya Lowlands in terms of both environmental and cultural resilience and with a focus on downturns that occurred in the Terminal Preclassic (second century Common Era) and Terminal Classic (9th and 10th centuries CE) periods. This examination of available data indicates that the elevated interior areas of the Yucatán Peninsula were more susceptible to system collapse and less suitable for resilient recovery than adjacent lower-lying areas. PMID:22371571

Landscape Archeology: Remote Sensing Investigation of the Ancient Maya in the Peten Rainforest of Northern Guatemala

Science.gov (United States)

Sever, Thomas L.; Irwin, Daniel E.; Arnold, James E. (Technical Monitor)

2002-01-01

Through the use of airborne and satellite imagery we are improving our ability to investigate ancient Maya settlement, subsistence, and landscape modification in this dense forest region. Today the area is threatened by encroaching settlement and deforestation. However, it was in this region that the Maya civilization began, flourished, and abruptly disappeared for unknown reasons in the 9th century AD. At the time of their collapse they had attained one of the highest population densities in human history. How the Maya were able to successfully manage water and feed this dense population is not well understood at this time. A NASA-funded project used remote sensing technology to investigate large seasonal swamps (bajos) that make up 40 percent of the landscape. Through the use of remote sensing, ancient Maya features such as sites, roadways, canals and water reservoirs have been detected and verified through ground reconnaissance. The results of this preliminary research cast new light on the adaptation of the ancient Maya to their environment. Microenvironmental variation within the wetlands was elucidated and the different vegetation associations identified in the satellite imagery. More than 70 new archeological sites within and at the edges of the bajo were mapped and tested. Modification of the landscape by the Maya in the form of dams and reservoirs in the Holmul River and its tributaries and possible drainage canals in bajos was demonstrated. The use of Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM), one-meter IKONOS satellite imagery, as well as high resolution airborne STAR-3i radar imagery--2.5 meter backscatter/10 meter Digital Elevation Model (DEM)--are opening new possibilities for understanding how a civilization was able to survive for centuries upon a karat topographic landscape. This understanding is critical for the current population that is currently experiencing rapid population growth and destroying the landscape through

Transcultural use of narcotic water lilies in ancient Egyptian and Maya drug ritual.

Science.gov (United States)

Emboden, W A

1981-01-01

Comparisons are made between ancient ritual uses of the flowers of Nymphaea (Nymphaeaceae) in Maya and Egyptian civilizations. Recurrent motifs encountered in the art of both of these ancient civilizations suggests that the role fo the water lily was that of a narcotic (psychodysleptic) used to mediate ecstasis among a priestly caste. Relevant literature is reviewed as are chemical data. Elements in the complex belief systems of these two civilizations need to be reinterpreted in view of the use of two water lilies as ritual narcotics. The species implicated are Nymphaea caerulea Sav., in Egypt, and N. ampla DC., among the Maya.

Two Holocene paleofire records from Peten, Guatemala: Implications for natural fire regime and prehispanic Maya land use

Science.gov (United States)

Anderson, Lysanna; Wahl, David B.

2016-01-01

Although fire was arguably the primary tool used by the Maya to alter the landscape and extract resources, little attention has been paid to biomass burning in paleoenvironmental reconstructions from the Maya lowlands. Here we report two new well-dated, high-resolution records of biomass burning based on analysis of macroscopic fossil charcoal recovered from lacustrine sediment cores. The records extend from the early Holocene, through the full arc of Maya prehistory, the Colonial, and post-Colonial periods (~ 9000 cal yr BP to the present). (Hereafter BP) The study sites, Lago Paixban and Lago Puerto Arturo, are located in northern Peten, Guatemala. Results provide the first quantitative analysis from the region demonstrating that frequent fires have occurred in the closed canopy forests since at least the early Holocene (~ 9000 BP), prior to occupation by sedentary agriculturalists. Following the arrival of agriculture around 4600 BP, the system transitioned from climate controlled to anthropogenic control. During the Maya period, changes in fire regime are muted and do not appear to be driven by changes in climate conditions. Low charcoal influx and fire frequency in the Earliest Preclassic period suggest that land use strategies may have included intensive agriculture much earlier than previously thought. Preliminary results showing concentrations of soot/black-carbon during the middle and late Preclassic periods are lower than modern background values, providing intriguing implications regarding the efficiency of Maya fuel consumption.

Two Holocene paleofire records from Peten, Guatemala: Implications for natural fire regime and prehispanic Maya land use

Science.gov (United States)

Anderson, Lysanna; Wahl, David

2016-03-01

Although fire was arguably the primary tool used by the Maya to alter the landscape and extract resources, little attention has been paid to biomass burning in paleoenvironmental reconstructions from the Maya lowlands. Here we report two new well-dated, high-resolution records of biomass burning based on analysis of macroscopic fossil charcoal recovered from lacustrine sediment cores. The records extend from the early Holocene, through the full arc of Maya prehistory, the Colonial, and post-Colonial periods ( 9000 cal yr BP to the present). (Hereafter BP) The study sites, Lago Paixban and Lago Puerto Arturo, are located in northern Peten, Guatemala. Results provide the first quantitative analysis from the region demonstrating that frequent fires have occurred in the closed canopy forests since at least the early Holocene ( 9000 BP), prior to occupation by sedentary agriculturalists. Following the arrival of agriculture around 4600 BP, the system transitioned from climate controlled to anthropogenic control. During the Maya period, changes in fire regime are muted and do not appear to be driven by changes in climate conditions. Low charcoal influx and fire frequency in the Earliest Preclassic period suggest that land use strategies may have included intensive agriculture much earlier than previously thought. Preliminary results showing concentrations of soot/black-carbon during the middle and late Preclassic periods are lower than modern background values, providing intriguing implications regarding the efficiency of Maya fuel consumption.

Stylistic Analysis of Maya Angelou’s Equality

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arina isti'anah

2017-11-01

Full Text Available This research presented the stylistic analysis of a poem by Maya Angelou, Equality. The poem was chosen as it became Angelou’s one of well-known poems. The Stylistic analysis aimed at comprehending the meanings of either literary or non-literary text by means of observing the language device used in the texts. In this article, the stylistic analysis was conducted to analyze Maya Angelou’s Equality. To achieve the goal of stylistic analysis, there were some language levels to observe; they were phonological, graphological, grammatical, and semantic levels. In the phonological level, the repetition of rhyme in some stanzas, assonance, consonance, and alliteration were used to voice Angelou’s dream about freedom for black people. In the graphological level, the use of prominent punctuation in stanzas 3, 6, and 9 stressed equality as the requirement for the freedom she expected. In the grammatical level, Angelou used pronoun I and you as the dominant words in the poem, revealed different class the poet experienced in the country. The use of metaphors in the poem brought the same meaning as freedom, voice, effort, and racism that black people experienced in America. This research concludes that stylistics applies to analyze literary work so that thorough appreciation to it can be achieved.

THE ASSISMENT OF MAYA VERNACULAR HERITAGE FROM UNIVERSE CONCEPT TO POVERTY CONCEPT

Directory of Open Access Journals (Sweden)

Aurelio Sánchez

2014-08-01

Full Text Available The traditional technique maya housing construction is the representation of the Mayan worldview, it is expressed through the name of each construction element meanings of the creation of the universe and man, is also referred to the body and the concept of a living. For many centuries it was the oral tradition and construction practices that kept this knowledge and knowing, until the process of deterioration with colonialism, the arrival of the Spanish was a watershed in its decline to the undervaluation and contempt. The international designations like vernacular architecture of little have served before the governmental programs that continue it cataloguing like noncompatible an inhabitable space with their criteria of “quality of life”, nor with the schemes of tie financing to industrialized materials. Recent proposals for housing support maya not provide its being as its spatial bioclimatic architecture and a way of life, encouraging new construction beyond its dynamic and undervalued the maya solar microhabitat. Urges a reassessment based on its original conception, in its sustainable architectural feature in your living space according to the social dynamics of its inhabitants and its recognition as a cultural heritage.

Founding Amerindian mitochondrial DNA lineages in ancient Maya from Xcaret, Quintana Roo.

Science.gov (United States)

González-Oliver, A; Márquez-Morfín, L; Jiménez, J C; Torre-Blanco, A

2001-11-01

Ancient DNA from the bone remains of 25 out of 28 pre-Columbian individuals from the Late Classic-Postclassic Maya site of Xcaret, Quintana Roo, was recovered, and mitochondrial DNA (mtDNA) was amplified by using the polymerase chain reaction. The presence of the four founding Amerindian mtDNA lineages was investigated by restriction analysis and by direct sequencing in selected individuals. The mtDNA lineages A, B, and C were found in this population. Eighty-four percent of the individuals were lineage A, whereas lineages B and C were present at low frequencies, 4% and 8%, respectively. Lineage D was absent from our sample. One individual did not possess any of the four lineages. Six skeletons out of 7 dated from the Late Classic period were haplotype A, whereas 11 skeletons out of 16 dated from the Postclassic period were also haplotype A. The distribution of mtDNA lineages in the Xcaret population contrasts sharply with that found in ancient Maya from Copán, which lack lineages A and B. On the other hand, our results resemble more closely the frequencies of mtDNA lineages found in contemporary Maya from the Yucatán Peninsula and in other Native American contemporary populations of Mesoamerican origin. Copyright 2001 Wiley-Liss, Inc.

Modern tree species composition reflects ancient Maya "forest gardens" in northwest Belize.

Science.gov (United States)

Ross, Nanci J

2011-01-01

Ecology and ethnobotany were integrated to assess the impact of ancient Maya tree-dominated home gardens (i.e., "forest gardens"), which contained a diversity of tree species used for daily household needs, on the modern tree species composition of a Mesoamerican forest. Researchers have argued that the ubiquity of these ancient gardens throughout Mesoamerica led to the dominance of species useful to Maya in the contemporary forest, but this pattern may be localized depending on ancient land use. The tested hypothesis was that species composition would be significantly different between areas of dense ancient residential structures (high density) and areas of little or no ancient settlement (low density). Sixty-three 400-m2 plots (31 high density and 32 low density) were censused around the El Pilar Archaeological Reserve in northwestern Belize. Species composition was significantly different, with higher abundances of commonly utilized "forest garden" species still persisting in high-density forest areas despite centuries of abandonment. Subsequent edaphic analyses only explained 5% of the species composition differences. This research provides data on the long-term impacts of Maya forests gardens for use in development of future conservation models. For Mesoamerican conservation programs to work, we must understand the complex ecological and social interactions within an ecosystem that developed in intimate association with humans.

Patterned Ground in Wetlands of the Maya Lowlands: Anthropogenic and Natural Causes

Science.gov (United States)

Beach, T.; Beach, S. L.

2004-12-01

We use geological and archaeological evidence to understand the formation of patterned ground in perennial and seasonal wetlands in the karst depressions of Belize and Guatemala. Some scholars have argued that these features are the remnants of ancient Maya wetland fields, chinampas, on which intensive cultivation produced food that could begin to nourish the extremely high population of the Late Classic (A.D. 550-850). Others have argued that these were natural features or that they represent landscape manipulation for rising sea level in the Preclassic (1000 B.C. -A.D. 250). We present the evidence for ancient intensive agriculture and natural landscape formation with multiple proxies: excavated field and canal features, artifacts, pollen, soil stratigraphy, and water chemistry. Evidence thus far suggests that many regional depressions have Preclassic (1200 BC to AD 200) or earlier paleosols, buried from 1-2 m by eroded soils induced by Maya land use practices. These paleosols were buried by eroded sediments from uplands and by precipitation of gypsum from rising groundwater. The sedimentation occurred largely between the Preclassic and Late Classic, when ancient Maya farmers built canals in pre-existing low spots to reclaim these wetlands. Thus, stable natural processes, environmental change, and human manipulation have acted together to form patterned wetland ground over the later Holocene.

Justicia indígena maya en el sureste de México

Directory of Open Access Journals (Sweden)

Juana Luisa Ríos Zamudio

2011-01-01

Full Text Available A más de diez años de haberse implementado en Quintana Roo, México, un sistema de justicia propio para las comunidades mayas de la entidad, y pese a lo acelerado de su crecimiento y arraigo, su estructura, funcionamiento y principios éticos que lo rigen han sido poco estudiados. Este trabajo tiene como objetivo analizar su funcionamiento desde la sociología jurídica, tomando como base las constancias de actuación de los jueces tradicionales. Se podrá ver que gracias a su polivalente actuación, los jueces tradicionales son hoy una figura socialmente legitimada al interior de las comunidades mayas, aun habiendo sido creada e implementada "desde fuera" por las autoridades estatales hace apenas poco más de una década.

Paleoenvironmental and Paleoecological Reconstruction of the Ancient Maya Port Site of Vista Alegre, Quintana Roo, Mexico

Science.gov (United States)

Rissolo, D.; Jaijel, R.; Glover, J. B.; Goodman, B.; Beddows, P. A.; Carter, A.; Smith, D.

2013-12-01

Ancient Maya ports along the largely unstudied northeast coast of the Yucatan Peninsula once supported a network of trade routes linking people, goods, and ideas from across Mesoamerica. The Costa Escondida Project has focused on the interrelationships between the ancient Maya and their dynamic coastal environment along the shores of the Laguna Holbox. Central to our interdisciplinary efforts is a paleoenvironmental and paleoecological reconstruction of the key port of Vista Alegre - a low-lying island surrounded by a complex mosaic of costal ecosystems, sedimentological facies, and hydrological conditions. Geoarchaeological field methods, such as sediment coring, have made possible multiproxy analyses that enable us to better understand sea level fluctuations and the morphology of the shoreline and harboring locations over time, as well as changes in ecosystem biodiversity, which would have presented the maritime Maya with unique challenges and opportunities.

Correlating the Ancient Maya and Modern European Calendars with High-Precision AMS 14C Dating

Science.gov (United States)

Kennett, Douglas J.; Hajdas, Irka; Culleton, Brendan J.; Belmecheri, Soumaya; Martin, Simon; Neff, Hector; Awe, Jaime; Graham, Heather V.; Freeman, Katherine H.; Newsom, Lee; Lentz, David L.; Anselmetti, Flavio S.; Robinson, Mark; Marwan, Norbert; Southon, John; Hodell, David A.; Haug, Gerald H.

2013-04-01

The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial. We report a series of high-resolution AMS 14C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel between AD 658-696. This strongly supports the Goodman-Martínez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.

El cemento y el concreto de los mayas

OpenAIRE

Horacio Ramírez de Alba; Ramiro Pérez Campos; Heriberto Díaz Coutiño

1999-01-01

Se realiza un estudio técnico sobre los materiales utilizados por los constructores mayas, quienes lograron obras cuyos vestigios maravillan hoy al mundo. Se presentan los resultados obtenidos al realizar pruebas físicas y químicas en muestras de estucos, morteros y concretos provenientes de zonas arqueológicas, principalmente Palenque y Yaxchilán, en el estado de Chiapas, México.

Quantitative approach on SEM images of microstructure of clay soils

Institute of Scientific and Technical Information of China (English)

施斌; 李生林; M.Tolkachev

1995-01-01

The working principles of Videolab Image Processing System (VIPS), the examining methods of orientation of microstructural units of clay soils and analysing results on SEM images of some typical microstructures of clay soils using the VIPS are introduced.

Family and the Bildungsroman Tradition in Maya Angelou's I Know ...

African Journals Online (AJOL)

The paper examines family and the bildungsroman process in Maya Angelou's I know Why the Caged Bird Sings and Chimamanda Adichie's Purple Hibiscus. The study is carried out mainly through Sigmund Freud's Psychoanalytical critical theory. The paper notes that the nuclear family's responsibility at grooming the ...

El Teatro Maya como travestismo cultural. Una lectura performativa y descolonizadora de su arquitectura

OpenAIRE

Hoechtl, Nina

2015-01-01

Este texto emula la forma y estructura de un guion dramático. En él se desarrolla una visita guiada al Teatro Maya, a través de la cual se pretende mostrar las maneras en que lo cultural diferente y lo cultural exótico habitan la arquitectura. El texto aborda este análisis desde una perspectiva específica, la del travestismo cultural, poniendo especial atención en el contexto arquitectónico, cultural e histórico particular del Teatro Maya, que se inauguró en 1927 en el Centro de Los Angeles e...

Clay and concrete brick

CSIR Research Space (South Africa)

Dlamini, MN

2014-03-01

Full Text Available Brick is one of the most used and versatile building materials in use today. Bricks can be defined as modular units connected by mortar in the formation of a building system or product. Commonly the word brick is used to refer to clay bricks, which...

Nacionalismo maya y descolonización política: Luis de Lión y El tiempo principia en Xibalbá

OpenAIRE

del Valle Escalante, Emilio; University of North Carolina, Chapel Hill

2015-01-01

Este artículo analiza la novela El tiempo principia en Xibalbá (1985) del escritor maya kaqchikel Luis de Lión (1939-1984), considerada la primera novela escrita por un escritor maya en Guatemala. Leída como una de las primeras manifestaciones epistemológicas y políticas del llamado Movimiento Maya en Guatemala, la obra de Lión, como se argumenta en este trabajo, desmitifica y desarticula construcciones tradicionales y estereotipadas del mundo indígena en el discurso indigenista (la literatur...

Putting Us on the Map: Remote Sensing Investigation of the Ancient Maya Landscape

Science.gov (United States)

Sever, Thomas L.; Saturno, William

2004-01-01

A common problem for archaeologists studying ancient settlement in the Maya Lowlands is overcoming the dense vegetation in order to obtain an accurate regional perspective of the presence of archaeological sites, their exact locations and their overall extents. Most often this is done by extensive ground surveys in which many individuals chop parallel paths through the vegetation in search of sites. Once a site is found an effort is made to mark its location on a regional map and to explore its perimeter. Obtaining locational information has been made dramatically easier in recent years with the advent of improved Global Positioning Systems (GPS), however the process of initial identification of sites and the determination of their borders is exceedingly labor intensive and has remained relatively unchanged since the beginning of settlement surveys in the region in the 1950 s. Currently, we are revolutionizing settlement survey in the Maya Lowlands by using remotely sensed data from IKONOS, Quickbird, and Eo 1, satellites as well as airborne AIRSAR radar data. The Ancient Maya built their cities, towns and even their smallest hamlets using excavated limestone and lime plasters. We propose that the decay of these structures provides a unique microenvironment for the growth of vegetation as the levels of moisture and nutrition within the ruins vary substantially from those in the surrounding forest. These microenvironmental differences on the ground are likewise represented by compositional differences in the forest canopy both in the species present and in leaf color (representing moisture/nutritional stress) visible through the analysis of high-resolution satellite data. In this way the detailed analysis of forest composition can reveal a detailed picture of the ancient settlements that lie beneath it. Preliminary examinations using this technique have been very successful and we are refining these techniques in order to efficiently comprehend the details of

Putting us on the Map: Remote Sensing Investigation of the Ancient Maya Landscape

Science.gov (United States)

Sever, Thomas L.; Saturno, William; Irwin, Daniel E.

2004-01-01

A common problem for archaeologists studying ancient settlement in the Maya Lowlands is overcoming the dense vegetation in order to obtain an accurate regional perspective of the presence of archaeological sites, their exact locations and their overall extents. Most often this is done by extensive ground surveys in which many individuals chop parallel paths through the vegetation in search of sites. Once a site is found an effort is made to mark its location on a regional map and to explore its perimeter. Obtaining locational information has been made dramatically easier in recent years with the advent of improved Global Positioning Systems (GPS), however the process of initial identification of sites and the determination of their borders is exceedingly labor intensive and has remained relatively unchanged since the beginning of settlement surveys in the region in the 1950's. Currently, we are revolutionizing settlement survey in the Maya Lowlands by using remotely sensed data from IKONOS, Quickbird, and Eol, satellites. The Ancient Maya built their cities, towns and even their smallest hamlets using excavated limestone and lime plasters. We propose that the decay of these structures provides a unique microenvironment for the growth of vegetation as the levels of moisture and nutrition within the ruins vary substantially from those in the surrounding forest. These microenvironmental differences on the ground are likewise represented by compositional differences in the forest canopy both in the species present and in leaf color (representing moisture/nutritional stress) visible through the analysis of high- resolution satellite data. In this way the detailed analysis of forest composition can reveal a detailed picture of the ancient settlements that lie beneath it. Preliminary examinations using this technique have been very successful and we are refining these techniques in order to efficiently comprehend the details of Ancient Maya settlement in the Lowlands.

Mayariggauksen Mekanismit : mihin Maya-rigin perustoiminnot pohjautuvat

OpenAIRE

Reimi, Roope

2015-01-01

Tämä on tutkielma Mayan yleisimpien riggaustyökalujen ja mekanismien toiminnasta ja yleinen katsaus Mayan pohjarakenteeseen. Maya on Autodeskin yleiskäytännöllinen 3D-ohjelmisto, joka on saanut teollisuuden aloilla maineen luotettavana, mutta haastavana animaatioalustana. Tässä tutkielmassa aion selvittää muutamia konsepteja, jotka saattavat hämmentää Mayassa ja avata sen logiikkaa toimintojensa takana. Aion myös pureutua syvemmin muutamien Mayan perus riggaustyökalujen toimintaan ja millaine...

El cemento y el concreto de los mayas

Directory of Open Access Journals (Sweden)

Horacio Ramírez de Alba

1999-01-01

Full Text Available Se realiza un estudio técnico sobre los materiales utilizados por los constructores mayas, quienes lograron obras cuyos vestigios maravillan hoy al mundo. Se presentan los resultados obtenidos al realizar pruebas físicas y químicas en muestras de estucos, morteros y concretos provenientes de zonas arqueológicas, principalmente Palenque y Yaxchilán, en el estado de Chiapas, México.

Guatemala conservation concession for the Maya Biosphere Reserve

OpenAIRE

Conservation International

2007-01-01

Metadata only record The national government of Guatemala has issued timber concessions to local communities within its 2 million hectare Maya Biosphere Reserve. Working under this framework, CI is proposing a conservation concession contract with two communities. The concessions would be designed to pay salaries for conservation managers, to invest in projects such as guiding tourists to nearby archaeological sites and to provide community services such as education and health care, in ex...

Clay minerals in sandstone uranium deposits: radwaste applications

International Nuclear Information System (INIS)

Brookins, D.G.

1990-01-01

Clay minerals play an important role in the genesis of uranium deposits in sandstones. They incorporate the rate earths (REE), U, Sb, Th, Cs, Rb, Sr, Y, Ba, and even small amounts of chalcophiles. These minerals possess analog elements for many of the radwaste fission products as well as actinides and some actinide daughters. In sandstone uranium deposits, clay minerals are also associated with sulfide minerals, usually pyrite, and organic carbonaceous matter. The primary clay minerals are usually smectites, illites, chlorites and mixed layer varieties. The integrity of these clay minerals is demonstrated by their retention of formational-mineralization ages determined by Rb-Sr geochronologic investigation of the Grants Mineral Belt of the United States. The importance of the clay minerals as analog for parts of the multi-barrier concept in radwaste disposal is their ability to impede water penetration into - and movement of key elements out of uranium rich zones. The clay minerals further sorb and in other ways incorporate into their structures many fission products and actinide analogs from man-made nuclear wastes. 22 refs., 1 fig., 3 tabs

A late Holocene tephrochronology for the Maya Lowlands, Central America

Science.gov (United States)

Nooren, K.; Huizinga, A.; Hoek, W.; Bergen, M. V.; Middelkoop, H.

2012-12-01

The Maya Lowlands in southern Mexico, Guatemala and Belize were densely populated for thousands of years, and have been the subject of intensive studies on the interaction between humans and their environment. Accurate radiocarbon dating of proxy records and disrupting events has proved to be difficult due to the lack of organic material in many deposits and the 'old carbon effect' related to the calcareous geology of the Yucatan Peninsula. So far, tephrostratigraphy has hardly been used to define time markers for palynological, limnological and archaeological studies in this region, despite the frequent occurrence of tephra fall. With the objective to fill this gap, we developed a tephrochronology for the Maya Lowlands using sediment cores from a flood basin of the Usumacinta-Grijalva delta in southern Mexico. Tephrostratigraphy and radiocarbon dating were used to estimate the timing of past volcanic eruptions, and chemical compositions of glass shards were used to identify potential sources. At least six tephralayers were deposited since 2000 BC, the most notable representing eruptions of El Chichón volcano in the 5th and 15th century AD. The high sulphur emissions accompanying El Chichón's eruptions allowed testing of our age-depth model through a correlation with volcanic sulphate peaks in ice cores from Greenland and Antarctica. We demonstrate the applicability of the established tephrochronological framework in a detailed chronological reconstruction of the formation of the world's largest late Holocene beach ridge plain in southern Mexico. This plain with over 500 beach ridges is a highly sensitive recorder of combined sea level rise, subsidence, storm activity and changes in climate and upstream land use since the dawn of Olmec and Maya cultures circa 5000 years ago.

Game Art Complete All-in-One; Learn Maya, 3ds Max, ZBrush, and Photoshop Winning Techniques

CERN Document Server

Gahan, Andrew

2008-01-01

A compilation of key chapters from the top Focal game art books available today - in the areas of Max, Maya, Photoshop, and ZBrush. The chapters provide the CG Artist with an excellent sampling of essential techniques that every 3D artist needs to create stunning game art. Game artists will be able to master the modeling, rendering, rigging, and texturing techniques they need - with advice from Focal's best and brightest authors. Artists can learn hundreds of tips, tricks and shortcuts in Max, Maya, Photoshop, ZBrush - all within the covers of one complete, inspiring reference

Increasing temperature exacerbated Classic Maya conflict over the long term

Science.gov (United States)

Carleton, W. Christopher; Campbell, David; Collard, Mark

2017-05-01

The impact of climate change on conflict is an important but controversial topic. One issue that needs to be resolved is whether or not climate change exacerbates conflict over the long term. With this in mind, we investigated the relationship between climate change and conflict among Classic Maya polities over a period of several hundred years (363-888 CE). We compiled a list of conflicts recorded on dated monuments, and then located published temperature and rainfall records for the region. Subsequently, we used a recently developed time-series method to investigate the impact of the climatic variables on the frequency of conflict while controlling for trends in monument number. We found that there was a substantial increase in conflict in the approximately 500 years covered by the dataset. This increase could not be explained by change in the amount of rainfall. In contrast, the increase was strongly associated with an increase in summer temperature. These finding have implications not only for Classic Maya history but also for the debate about the likely effects of contemporary climate change.

Clay membrane made of natural high plasticity clay

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1998-01-01

Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...

Clay membrane made of natural high plasticity clay:

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1999-01-01

Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

Thermal volume changes in clays and clay-stones

International Nuclear Information System (INIS)

Delage, P.; Sulem, J.; Mohajerani, M.; Tang, A.M.; Monfared, M.

2012-01-01

Document available in extended abstract form only. The disposal of high activity exothermic radioactive waste at great depth in clay host rocks will induce a temperature elevation that has been investigated in various underground research laboratories in Belgium, France and Switzerland through in-situ tests. Thermal effects are better known in clays (in particular Boom clay) than in clay-stone (e.g. Opalinus clay and Callovo-Oxfordian clay-stone). In terms of volume changes, Figure 1 confirms the findings of Hueckel and Baldi (1990) that volume changes depend on the over-consolidation ratio (OCR) of the clay. In drained conditions, normally consolidated clays exhibit plastic contraction when heated, whereas over-consolidated clay exhibit elastic dilation. The nature of thermal volume changes in heated clays obviously has a significant effect on thermally induced pore pressures, when drainage is not instantaneous like what occurs in-situ. Compared to clays, the thermal volume change behaviour of clay-stones is less well known than that of clays. clay-stone are a priori suspected to behave like over-consolidated clays. In this paper, a comparison of recent results obtained in the laboratory on the drained thermal volume changes of clay-stones is presented and discussed. It is difficult to run drained mechanical tests in clay-stones like the Opalinus clay and the Callovo-Oxfordian clay-stone because of their quite low permeability (10 -12 - 10 -13 m/s). This also holds true for thermal tests. Due to the significant difference in thermal expansion coefficient between minerals and water, it is necessary to adopt very slow heating rate (0.5 - 1 C/h) to avoid any thermal pressurization. To do so, a new hollow cylinder apparatus (100 mm external diameter, 60 mm internal diameter) with lateral drainages reducing the drainage length to half the sample thickness (10 mm) has been developed (Monfared et al. 2011). The results of a drained cyclic thermal test carried out on

Basic Deformation Parameters of Solid Clay Bricks and Small Masonry Walls

Directory of Open Access Journals (Sweden)

P. Bouška

2000-01-01

Full Text Available The basic mechanical properties of clay brick masonry and its components were experimentally investigated in the laboratories of the Klokner Institute. The test specimens of masonry materials and the relevant mechanical properties have been identified in solid clay bricks and cement-lime mortar. The aim of the research activity was to study both the deformability of the prevailing type of clay masonry in the existing buildings, i.e. the masonry made from the solid clay units and the lime-cement mortar, and the most important mechanical properties of masonry components.

Elements of success in cooperatives conformed by Maya women in the Yucatan Peninsula, Mexico

Directory of Open Access Journals (Sweden)

Maria Cristina Osorio Vázquez

2016-05-01

Full Text Available This paper describes different elements leading to the success of cooperatives formed by indigenous Maya women of the Yucatan Peninsula in Mexico. These elements have shown to facilitate the sustainability (permanence over time of the cooperatives and their presence in the market, while improving the work environment and enhancing the practice of honesty. All these elements have generated an increase in the number of clients and beneficiaries due to their trustable relationships. As can be appreciated in this study, indigenous Maya women living in the Yucatan Peninsula are demonstrating an innovative way to do business, which has resulted in greater social benefits and profitability through social capital, ethical leadership and monitoring of actions.

Critical Pedagogy in HIV-AIDS Education for a Maya Immigrant Community

Science.gov (United States)

Schoorman, Dilys; Acosta, Maria Cristina; Sena, Rachel; Baxley, Traci

2012-01-01

In this article the authors discuss how the perspectives of Paulo Freire were instructive in addressing the challenges of HIV-AIDS education in Guatemalan Maya immigrant communities with minimal formal education and literacy. The forging of a community-based, collaborative, educational program offers several implications for effective teaching and…

Three-dimensional visualization of nanostructured surfaces and bacterial attachment using Autodesk® Maya®

Science.gov (United States)

Boshkovikj, Veselin; Fluke, Christopher J.; Crawford, Russell J.; Ivanova, Elena P.

2014-02-01

There has been a growing interest in understanding the ways in which bacteria interact with nano-structured surfaces. As a result, there is a need for innovative approaches to enable researchers to visualize the biological processes taking place, despite the fact that it is not possible to directly observe these processes. We present a novel approach for the three-dimensional visualization of bacterial interactions with nano-structured surfaces using the software package Autodesk Maya. Our approach comprises a semi-automated stage, where actual surface topographic parameters, obtained using an atomic force microscope, are imported into Maya via a custom Python script, followed by a `creative stage', where the bacterial cells and their interactions with the surfaces are visualized using available experimental data. The `Dynamics' and `nDynamics' capabilities of the Maya software allowed the construction and visualization of plausible interaction scenarios. This capability provides a practical aid to knowledge discovery, assists in the dissemination of research results, and provides an opportunity for an improved public understanding. We validated our approach by graphically depicting the interactions between the two bacteria being used for modeling purposes, Staphylococcus aureus and Pseudomonas aeruginosa, with different titanium substrate surfaces that are routinely used in the production of biomedical devices.

A distribution analysis of the central Maya lowlands ecoinformation network: its rises, falls, and changes

Directory of Open Access Journals (Sweden)

Joel D. Gunn

2017-03-01

Full Text Available We report a study of central Maya lowland dynastic information networks, i.e., six cities' external elite ceramic influences, and how they reflect the decision-making practices of Maya elites over 3000 years. Forest cover, i.e., Moraceae family pollen, was added to the network analysis to provide ecological boundary conditions, thus ecologically moderated information networks. Principal components analysis revealed three dominant patterns. First, the networking of interior cities into powerful polities in the Late Preclassic and Classic periods (400 BCE-800 CE. In a second pattern, coastal cities emerged as key entrepôts based on marine navigation (Terminal and Postclassic periods, 800-1500 CE. Climate dynamics and sustainability considerations facilitated the transition. Forest cover, a measure of ecosystem health, shows interior forests diminished as interior cities networked but rebounded as their networks declined. By contrast, coastal forests flourished with networks implying that the marine-based economy was sustainable. Third, in the Classic, the network-dominant coast, west or east, changed with interior polities' political struggles, the critical transition occurring after 695 CE as Tikal gained dominance over the Calakmul-Caracol alliance. Beginning with the Late Preclassic about 2000 years ago, it is possible to assign names to the decision makers by referencing the growing literature on written Maya records. Although the detectable decision sequence evident in this analysis is very basic, we believe it does open possible avenues to much deeper understanding as the study proceeds into the future. The Integrated History and Future of People on Earth-Maya working group that sponsored the analysis anticipates that it will provide actionable social science intelligence for future decision making at the global scale.

Data from The Production and Exchange of Moulded-carved Ceramics and the ‘Maya Collapse’

Directory of Open Access Journals (Sweden)

Carmen Ting

2015-05-01

Full Text Available This dataset comprises the bulk chemical composition and petrographic description of 62 samples of Ahk’utu’ Moulded-carved vases selected from eight archaeological sites across Belize. The bulk chemical compositional data was produced by instrumental neutron activation analysis (INAA, whereas the mineralogical and textural features of the ceramics were highlighted by thin-section petrography. These two types of data are complementary to characterising the compositional variability within and between assemblages; and more importantly, contributing to a better understanding of the craft organisation of finewares in the Maya lowlands during the so-called ‘Classic Maya Collapse’ or the ‘Terminal Classic‘ (ca. AD 800–950.

La violencia sexual como genocidio. Memoria de las mujeres mayas sobrevivientes de violación sexual durante el conflicto armado en Guatemala

Directory of Open Access Journals (Sweden)

Amandine Fulchiron

2016-01-01

Full Text Available Este art culo es producto de la investigaci n/ acci n participativa llevada a cabo del 2005 al 2009 en el marco del proceso pol tico y social impulsado por Actoras de Cambio junto con 54 mujeres mayas de cuatro grupos tnicos distintos ?Q eqchi , Mam, Chuj, y Kaqchikel? sobrevivientes de violaci n sexual durante el con icto armado interno en Guatemala (1960-1996. En l analizamos el uso sistem tico y masivo de la violaci n sexual contra las mujeres mayas dentro del marco de la pol tica contrainsurgente en Guatemala, nombr ndolo y denunci ndolo como feminicidio y genocidio; evidenciamos c mo la violaci n sexual fue utilizada por el Estado para destruir la continuidad biol gica, social y cultural del pueblo maya a trav s del cuerpo de las mujeres. Adem s, demostramos la centralidad e intencionalidad pol tica de la violaci n sexual para someter y masacrar a las mujeres. El trabajo se estructur con base en una epistemolog a feminista articulada con la de la cosmovisi n maya. Ello implic poner en el centro de la investigaci n voces y experiencias silenciadas por la visi n androc ntrica y racista del mundo. Requiri , adem s, una voluntad colectiva de desvelar c mo se imbrican y sintetizan los diferentes sistemas de opresi n en el cuerpo de las mujeres mayas. Esta investigaci n da cuenta de una experiencia concreta y colectiva de memoria y sanaci n entre mujeres mayas, mestizas y europeas, que ha posibilitado rehabitar el cuerpo, la vida y la comunidad despu s de la violaci n sexual genocida desde un nuevo lugar justo, digno y libre para las mujeres.

Holocene debris flows on the Colorado Plateau: The influence of clay mineralogy and chemistry

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Webb, R.H.; Griffiths, P.G.; Rudd, L.P.

2008-01-01

Holocene debris flows do not occur uniformly on the Colorado Plateau province of North America. Debris flows occur in specific areas of the plateau, resulting in general from the combination of steep topography, intense convective precipitation, abundant poorly sorted material not stabilized by vegetation, and the exposure of certain fine-grained bedrock units in cliffs or in colluvium beneath those cliffs. In Grand and Cataract Canyons, fine-grained bedrock that produces debris flows contains primarily single-layer clays - notably illite and kaolinite - and has low multilayer clay content. This clay-mineral suite also occurs in the colluvium that produces debris flows as well as in debris-flow deposits, although unconsolidated deposits have less illite than the source bedrock. We investigate the relation between the clay mineralogy and major-cation chemistry of fine-grained bedrock units and the occurrence of debris flows on the entire Colorado Plateau. We determined that 85 mapped fine-grained bedrock units potentially could produce debris flows, and we analyzed clay mineralogy and major-cation concentration of 52 of the most widely distributed units, particularly those exposed in steep topography. Fine-grained bedrock units that produce debris flows contained an average of 71% kaolinite and illite and 5% montmorillonite and have a higher concentration of potassium and magnesium than nonproducing units, which have an average of 51% montmorillonite and a higher concentration of sodium. We used multivariate statistics to discriminate fine-grained bedrock units with the potential to produce debris flows, and we used digital-elevation models and mapped distribution of debris-flow producing units to derive a map that predicts potential occurrence of Holocene debris flows on the Colorado Plateau. ?? 2008 Geological Society of America.

Clay Play

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Rogers, Liz; Steffan, Dana

2009-01-01

This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

Lithological and hydrological influences on ground-water composition in a heterogeneous carbonate-clay aquifer system

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Kauffman, S.J.; Herman, J.S.; Jones, B.F.

1998-01-01

The influence of clay units on ground-water composition was investigated in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida, known as the Intermediate aquifer system. Regionally, the ground water is recharged inland, flows laterally and to greater depths in the aquifer systems, and is discharged vertically upward at the saltwater interface along the coast. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The chemical composition of the ground water in the carbonate bedrock is significantly different from that of the pore water in the clay layers. Dissolution of clays and opaline silica results in high silica concentrations relative to water in other parts of the Intermediate aquifer system. Water enriched in chloride relative to the overlying and underlying ground water recharges the aquifer inland where the confining clay layer is absent, and it dissolves carbonate and silicate minerals and reacts with clays along its flow path, eventually reaching this coastal site and resulting in the high chloride and silica concentrations observed in the middle part of the Intermediate aquifer system. Reaction-path modeling suggests that the recharging surficial water mixes with sulfate-rich water upwelling from the Upper Floridan aquifer, and carbonate mineral dissolution and precipitation, weathering and exchange reactions, clay mineral diagenesis, clay and silica dissolution, organic carbon oxidation, and iron and sulfate reduction result in the observed water compositions.A study was conducted to clarify the influence of clay units on ground-water composition in a heterogeneous

Factors that influence the design of modified clays - or how knowing your clay can save your day

International Nuclear Information System (INIS)

Gates, W.P.; Slade, P.G.

1998-01-01

Full text: Smectites vary greatly in their permanent layer charge characteristics, including total charge, distribution of charge between tetrahedral and octahedral sheets and heterogeneity of charge from flake to flake. Smectites and vermiculites are different from the micaceous layer silicates in their ability to swell by the uptake of cations and polar and non polar solvents. Vermiculites differ from the smectites predominantly in the large contribution of tetrahedrally located charge relative to their total layer charge density. Understanding of the complex relations between layer charge and interlayer space of clay mineral surfaces can be applied toward the design of optimal organically modified clays suitable for environmental and industrial uses. In general, it is known that smectite charge density dictates the total amount of modifying organic cation that can be added to a particular clay, the orientation that the organic cation adopts within the interlayer spaces with respect to the siloxane surfaces of the clay and ultimately, the capacity of specific, organically modified clay to imbibe contaminants or other compounds. These same properties are dependent on the size and configuration of the modifying organic cation(s) as well as the percentage of the exchange capacity utilised, and thus, the amount of specific surface of the clay that is covered by the modifying organic cation. All these factors must be kept in mind in the design of inexpensive and useful modified clays. This paper reports on the application of polarised FT-IR and X-ray diffraction methods to the observation that layer charge density governs the orientation of trimethylphenylammonium (TMPA) cations in the interlayer space of smectites and vermiculites. The TMPA exchanged forms of several smectites and vermiculites were studied, whose layer charges ranged between X=0.37 and X=0.95 e - per formula unit and in which the location of charge varied with respect to the octahedral and

The University of Texas Maya Muon Project

International Nuclear Information System (INIS)

Schwitters, Roy

2007-01-01

Plans to explore the ruin of a Maya Pyramid in Belize using cosmic ray muon tomography will be described. Muon tomography was pioneered by Luis Alvarez in the 1960's to explore the Second Pyramid of Chephren in Egypt. Improvements in detector technology since the Alvarez experiment suggest that muon tomography may be a practical method for exploring and monitoring relatively large underground volumes when exposure times of order months are acceptable. A prototype detector based on Fermilab/MINOS scintillator strip/WLS fiber technology has been built and is being tested at UT Austin. Initial results using the detector will be discussed.

Las corridas de toros en los pueblos mayas orientales. Una aproximación etnográfica Bullfights at Eastern Maya Towns. An Etnographic Approach

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Andrés Medina Hernández

2010-01-01

Full Text Available En este ensayo realizamos una descripción de las corridas de toros en los pueblos mayas del oriente de Yucatán; la intención principal es situar esta expresión festiva en el contexto de los rituales que configuran las fiestas patronales, de tal manera que se destaque un hecho central: la profunda transformación de una fiesta de claros orígenes ibéricos en una manifestación profundamente entramada con una visión del mundo de raíz mesoamericana. Un eje de análisis es el que corresponde a las nociones de sacrificio que articulan los acontecimientos en el coso taurino con los más discretos que suceden en el interior de las casas de los dirigentes de los gremios, donde el sacrificio de puercos y pavos constituye la base de una gastronomía ritual. Otro más es el reconocimiento de referentes simbólicos espaciales y temporales de raíz mesoamericana que subyacen en todo el conjunto ritual que compone estas celebraciones de los mayas peninsulares.In this essay we describe bullfighting among the Maya peoples in eastern Yucatan. The fundamental aim is to situate this festive expression in the context of the rituals that shape the patron feasts, so as to stress a central fact: the transformation of a feast of clear Iberian origin into a manifestation that is deeply intertwined with a world vision of Mesoamerican ancestry. An analytical axis corresponds to the notions of sacrifice that articulate the events inside the bullring with those more discrete, that take place within the homes of the leaders of the guilds. Here, sacrifice of turkeys and pigs constitute the basis of a ritual gastronomy. Another axis is the acknowledgement of symbolic space and time referents of Mesoamerican origin underlying, as a whole, the ritual compound in these peninsular Mayan celebrations.

Heteroaggregation of titanium dioxide nanoparticles with natural clay colloids.

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Labille, Jérôme; Harns, Carrie; Bottero, Jean-Yves; Brant, Jonathan

2015-06-02

To better understand and predict the fate of engineered nanoparticles in the water column, we assessed the heteroaggregation of TiO2 nanoparticles with a smectite clay as analogues for natural colloids. Heteroaggregation was evaluated as a function of water salinity (10(-3) and 10(-1) M NaCl), pH (5 and 8), and selected nanoparticle concentration (0-4 mg/L). Time-resolved laser diffraction was used, coupled to an aggregation model, to identify the key mechanisms and variables that drive the heteroaggregation of the nanoparticles with colloids. Our data show that, at a relevant concentration, nanoparticle behavior is mainly driven by heteroaggregation with colloids, while homoaggregation remains negligible. The affinity of TiO2 nanoparticles for clay is driven by electrostatic interactions. Opposite surface charges and/or high ionic strength favored the formation of primary heteroaggregates via the attachment of nanoparticles to the clay. The initial shape and dispersion state of the clay as well as the nanoparticle/clay concentration ratio also affected the nature of the heteroaggregation mechanism. With dispersed clay platelets (10(-3) M NaCl), secondary heteroaggregation driven by bridging nanoparticles occurred at a nanoparticle/clay number ratio of greater than 0.5. In 10(-1) M NaCl, the clay was preaggregated into larger and more spherical units. This favored secondary heteroaggregation at lower nanoparticle concentration that correlated to the nanoparticle/clay surface area ratio. In this latter case, a nanoparticle to clay sticking efficiency could be determined.

Ball clay

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Virta, R.L.

2001-01-01

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Cultural Teaching: The Development of Teaching Skills in Maya Sibling Interactions.

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Maynard, Ashley E.

2002-01-01

Examined the development of teaching skills in older siblings responsible for teaching their younger siblings to become competent members of their culture among children from a Zinacantec Maya village in Chiapas, Mexico. Found that by age 4, children took responsibility for initiating teaching situations with their younger siblings, and by 8,…

Influence of clay mineralogy on clay based ceramic products

International Nuclear Information System (INIS)

Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

1996-01-01

Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

Earliest isotopic evidence in the Maya region for animal management and long-distance trade at the site of Ceibal, Guatemala.

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Sharpe, Ashley E; Emery, Kitty F; Inomata, Takeshi; Triadan, Daniela; Kamenov, George D; Krigbaum, John

2018-04-03

This study uses a multiisotope (carbon, nitrogen, oxygen, and strontium) approach to examine early animal management in the Maya region. An analysis of faunal specimens across almost 2,000 years (1000 BC to AD 950) at the site of Ceibal, Guatemala, reveals the earliest evidence for live-traded dogs and possible captive-reared taxa in the Americas. These animals may have been procured for ceremonial functions based on their location in the monumental site core, suggesting that animal management and trade began in the Maya area to promote special events, activities that were critical in the development of state society. Isotopic evidence for animal captivity at Ceibal reveals that animal management played a greater role in Maya communities than previously believed. Copyright © 2018 the Author(s). Published by PNAS.

How maya women respond to changing technology : The effect of helping behavior on initiating reproduction.

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Kramer, K L; McMillan, G P

1998-06-01

In the mid 1970s labor-saving technology was introduced into a Maya subsistence agricultural community that markedly increased the efficiency with which maize could be ground and water collected. This increased efficiency introduces a possible savings in the time that women allocate to work, which can be reapportioned to child care, food production, domestic work, or leisure. An earlier study suggested that this labor-saving technology had a positive effect in decreasing the age at which these Maya women begin their reproductive careers. Although there is a statistical association between the age at which women bear their first child and the introduction of modern technology, this association does not demonstrate that the decline in age at first birth is causally related to the presence of technology. This paper pursues two objectives to evaluate this potential causal relationship in greater detail. First, a theory relating technological change to the initiation of a reproductive career is briefly developed in order to make qualitative predictions about behavioral changes as a response to changing technology. Second, these predictions are then tested against time allocation data recently collected in this same Maya community.We suggest that both of the conditions necessary to initiate reproduction-fecundity and access to mates-fundamentally depend on the amount of help that a girl provides to her family. Further, the help that a girl provides can be affected by technological changes. Analyses show that when modern technology is available, unmarried young women do not change the time allocated to domestic tasks and child care, and allocate more time to low-energy leisure activities. This lack of perceived benefit to working more and a potential concomitant shift towards a positive energy balance may in part explain why Maya women leave home and initiate reproduction at a younger age after labor-saving technology is introduced.

Environmental and morphological changes around the Maritime Maya site Vista Alegre.

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Jaijel, Roy; Goodman, Beverly; Glover, Jeffrey; Beddows, Patricia; Carter, Alice; Smith, Derek; Rissolo, Dominique; Ben Avraham, Zvi

2016-04-01

The untold story of the Maritime Maya from the ancient port site Vista Alegre, is being written for the first time using a multidisciplinary effort that aims to reconstruct the environmental and morphological history of the site. Vista Alegre is located on the north-eastern tip of the Yucatan peninsula, on the ancient Maritime Maya trade routes. This strategic point between the Caribbean Sea and the Gulf of Mexico, offers an ideal setting for this kind of research, which will add to the general Maritime Maya history. The multidisciplinary effort is part of a larger project called "Costa Escodida". The project's main goals are to learn how the ancient inhabitants adapted to the environment, and to understand how this coastal site was integrated into broader maritime trade routes. The portion of the research presented here concentrates on the sites geomorphology and climate during the past 2-3000 years through the multiproxy analysis of marine sediment core and surface samples combined with archaeological data. This study aids our understanding of the site's possible functions, the environmental challenges the local inhabits contended with, and the identification of ancient harboring locations. The site was inhabited from the 9th century B.C until the mid 16th century A.D., with an apparent two century abandonment phase from the mid 7th to 9th century A.D. According to the results, five depositional phases can be recognized, and the related shoreline reconstruction shows a general trend of a flooded terrestrial landscape. This 'flooding' relates well to relative sea-level curves published in the region. Continued analysis of results from the research, and future research activities, may make it possible to recognize hurricane proxies in the sediment, locate underwater manmade seafaring artifacts and facilities, determine the range of economic opportunities for past inhabitants and quantify the availability of potable water sources.

Classic Maya Bloodletting and the Cultural Evolution of Religious Rituals: Quantifying Patterns of Variation in Hieroglyphic Texts

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Munson, Jessica; Amati, Viviana; Collard, Mark; Macri, Martha J.

2014-01-01

Religious rituals that are painful or highly stressful are hypothesized to be costly signs of commitment essential for the evolution of complex society. Yet few studies have investigated how such extreme ritual practices were culturally transmitted in past societies. Here, we report the first study to analyze temporal and spatial variation in bloodletting rituals recorded in Classic Maya (ca. 250–900 CE) hieroglyphic texts. We also identify the sociopolitical contexts most closely associated with these ancient recorded rituals. Sampling an extensive record of 2,480 hieroglyphic texts, this study identifies every recorded instance of the logographic sign for the word ch’ahb’ that is associated with ritual bloodletting. We show that documented rituals exhibit low frequency whose occurrence cannot be predicted by spatial location. Conversely, network ties better capture the distribution of bloodletting rituals across the southern Maya region. Our results indicate that bloodletting rituals by Maya nobles were not uniformly recorded, but were typically documented in association with antagonistic statements and may have signaled royal commitments among connected polities. PMID:25254359

Epilithic and endolithic bacterial communities in limestone from a Maya archaeological site.

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McNamara, Christopher J; Perry, Thomas D; Bearce, Kristen A; Hernandez-Duque, Guillermo; Mitchell, Ralph

2006-01-01

Biodeterioration of archaeological sites and historic buildings is a major concern for conservators, archaeologists, and scientists involved in preservation of the world's cultural heritage. The Maya archaeological sites in southern Mexico, some of the most important cultural artifacts in the Western Hemisphere, are constructed of limestone. High temperature and humidity have resulted in substantial microbial growth on stone surfaces at many of the sites. Despite the porous nature of limestone and the common occurrence of endolithic microorganisms in many habitats, little is known about the microbial flora living inside the stone. We found a large endolithic bacterial community in limestone from the interior of the Maya archaeological site Ek' Balam. Analysis of 16S rDNA clones demonstrated disparate communities (endolithic: >80% Actinobacteria, Acidobacteria, and Low GC Firmicutes; epilithic: >50% Proteobacteria). The presence of differing epilithic and endolithic bacterial communities may be a significant factor for conservation of stone cultural heritage materials and quantitative prediction of carbonate weathering.

Land, Water and Society in the Maya Lowlands

Science.gov (United States)

Murtha, T.; French, K.; Duffy, C.; Webster, D.

2013-12-01

This paper reports the results of our project investigating the long-term spatial and temporal dynamics of land use management, agricultural decision-making and patterns of resource availability in the tropical lowlands of Central America. Overall, our project combines diachronic environmental simulation with historic settlement pattern survey to address a series of long-standing questions about the coupled natural and human (CNH) landscape history in the Central Maya lowlands (at the UNESCO world heritage site of Tikal in the Maya Biosphere Reserve). The paper describes the preliminary results of our project, including changing patterns of land, water, settlement and political history using climate, soil and hydrologic modeling and time series spatial analysis of population and settlement patterns. The critical period of the study, 1000 BC until the present, begins with dispersed settlements accompanied by widespread deforestation and soil erosion. Population size and density grows rapidly for 800 years, while deforestation and erosion rates decline; however, there is striking evidence of political evolution during this period, including the construction of monumental architecture, hieroglyphic monuments detailing wars and alliances, and the construction of a defensive earthwork feature, signaling political territories and possibly delineating natural resource boundaries. Population decline and steady reforestation followed until more recent migration into the region, which has impacted the biosphere ecology. Building on our previous research regionally and comparative research completed in Belize and Mexico, we are modeling sample periods the 3,000-year landscape history of the region, comparing land and water availability to population distributions and what we know about political history. Simulations are generated using historic climate and land use data, primarily relying on the Erosion Productivity Impact Calculator (EPIC) and the Penn State Integrated

“Symptoms, Attitudes and Treatment Choices Surrounding Menopause among the Q’eqchi Maya of Livingston, Guatemala”

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Michel, Joanna L.; Veliz, Mario; Soejarto, Doel D.; Caceres, Armando; Mahady, Gail B

2006-01-01

The present study explored symptoms, attitudes and treatments surrounding women’s health and menopause among the Q’eqchi Maya of the eastern tropical lowlands of Guatemala. Data were obtained through participant observation, semi-structured interviews, focus groups and plant walks with 50 Q’eqchi community members from the state of Izabal, Municipality of Livingston, including 5 midwives, 5 traditional male healers and 8 postmenopausal women. Results indicate that the Q’eqchi Maya of Livingston possess their own cultural perceptions of women’s health which affect attitudes, symptoms and treatment choices during the menopausal transition. Since discussions of menstruation and menopause are considered cultural taboos among the Q’eqchi, many women mentioned experiencing excessive preoccupation when unanticipated and unfamiliar symptoms occurred. Furthermore, many women suffered from additional hardship when their spouse misinterpreted menopausal symptoms (vaginal dryness, sexual disinterest) as infidelity. Seven of the eight postmenopausal women interviewed indicated experiencing one or more symptoms during the menopausal transition, including headaches, anxiety, muscular pain, depression, and hot flashes. These results differ from the lack of symptomatology reported in previous studies in Mexico, but are in line with the result of menopausal research conducted among other Maya groups from the highlands of Guatemala. Although the Q’eqchi did not use a specific term for “hot flash”, three Q’eqchi women used the expression “baja presion” or a “lowering of blood pressure” to explain symptoms of profuse sweating followed by chills, heart palpitations, and emotional instability. The Q’eqchi Maya mentioned a number of herbal remedies to treat menopausal symptoms. Further research on these botanical treatments is needed in order to ascertain their safety and efficacy for continued use. PMID:16580764

Cultural and Climatic History of Cobá, a Lowland Maya City in Quintana Roo, Mexico

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Leyden, Barbara W.; Brenner, Mark; Dahlin, Bruce H.

1998-01-01

Lake Cobá, within the archaeological site of Cobá, provides evidence bearing on lowland Maya development. Palynological and geochemical data record multidecadal precipitation cycles from a 8.80-m, >8370-yr lake-sediment sequence terminating on bedrock. Late Classic sedimentation rates are rapid, but an anthropogenically derived colluvium layer is lacking. Initial vegetation was medium semi-deciduous and swamp forest. Forest clearance began 1650 B.C. (Early Preclassic) and maize first occurred at 850 B.C. (Middle Preclassic). Lakeside milpas existed until A.D. 720 (Late Classic) and then were moved from the city center as urbanization intensified and Lake Cobá was diked as a reservoir. Cobá was at most briefly vacated during the Classic Collapse and was abandoned after A.D. 1240, although some habitation persisted. The paleoecological record matches the archaeological history for Cobá, but pervasive disturbance muted the climatic signal, as the Late Classic drought is barely evident. The question whether economic trees were maintained within the city is unresolved. Maize cultivation allowed the Maya to develop a complex society and support a large population, but dependence on maize was ultimately doomed by variable rainfall. Precipitation in extreme years was insufficient to support crops, while native vegetation was not directly affected by drought that devastated Maya agriculture.

Earliest Mexican Turkeys (Meleagris gallopavo) in the Maya Region: implications for pre-Hispanic animal trade and the timing of turkey domestication.

Science.gov (United States)

Thornton, Erin Kennedy; Emery, Kitty F; Steadman, David W; Speller, Camilla; Matheny, Ray; Yang, Dongya

2012-01-01

Late Preclassic (300 BC-AD 100) turkey remains identified at the archaeological site of El Mirador (Petén, Guatemala) represent the earliest evidence of the Mexican turkey (Meleagris gallopavo) in the ancient Maya world. Archaeological, zooarchaeological, and ancient DNA evidence combine to confirm the identification and context. The natural pre-Hispanic range of the Mexican turkey does not extend south of central Mexico, making the species non-local to the Maya area where another species, the ocellated turkey (Meleagris ocellata), is indigenous. Prior to this discovery, the earliest evidence of M. gallopavo in the Maya area dated to approximately one thousand years later. The El Mirador specimens therefore represent previously unrecorded Preclassic exchange of animals from northern Mesoamerica to the Maya cultural region. As the earliest evidence of M. gallopavo found outside its natural geographic range, the El Mirador turkeys also represent the earliest indirect evidence for Mesoamerican turkey rearing or domestication. The presence of male, female and sub-adult turkeys, and reduced flight morphology further suggests that the El Mirador turkeys were raised in captivity. This supports an argument for the origins of turkey husbandry or at least captive rearing in the Preclassic.

Clay shale as host rock. A geomechanical contribution about Opalinus clay

International Nuclear Information System (INIS)

Lempp, Christof; Menezes, Flora; Sachwitz, Simon

2016-01-01

The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

Endothelial Nitric Oxide Synthase Haplotypes Are Associated with Preeclampsia in Maya Mestizo Women

Directory of Open Access Journals (Sweden)

Lizbeth Díaz-Olguín

2011-01-01

Full Text Available Preeclampsia is a specific disease of pregnancy and believed to have a genetic component. The aim of this study was to investigate if three polymorphisms in eNOS or their haplotypes are associated with preeclampsia in Maya mestizo women.

Use of marine robot`MAYA` for monitoring the Zuari and Mandovi esturine systems

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.A; Afzulpurkar, S.; Navelkar, G.S.; Maurya, P.K.; Fernandes, L.; Desa, E.S.; Madhan, R.; Shenoy, D.; Kurian, S.; Naik, H.; Nagvekar, S.; Vimalakumari, D.; Dalvi, H.S.; Manoharan, V.; deAraujo, B.A; Lamani, V.; Naik, N.; Mohan, N.; Dias, Albertina; Dias, A

to study the spatial distribution of biogeochemical properties in the Zuari and Mandovi Estuarine systems during the onset of tides. MAYA was repurposed as an ASV to tightly follow a path (Maurya, P et al., 2008) along the mid-section of the rivers...

El léxico cromático y la ideología maya Chromatic lexic and Maya ideology

Directory of Open Access Journals (Sweden)

Sanja Savkic

2011-01-01

Full Text Available Para acercarse al campo semántico de los colores, de primera importancia son diversos diccionarios de las lenguas mayances. El objetivo es hacer una descripción preliminar del vocabulario cromático, compuesto de cinco términos referidos a colores básicos que en el maya yucateco se llaman sak, ek', chak, k'an y ya'ax y significan "blanco", "negro", "rojo", "amarillo" y "verde-azul", respectivamente. El mismo vocabulario remite a determinadas categorías extralingüísticas que la lengua es capaz de acumular, reflejar y comunicar. Éstas dependen de una cultura particular, por lo que el estudio se amplía con las informaciones de diferentes fuentes escritas redactadas durante la época colonial. La intención es detectar los múltiples usos que se hacían en todos los ámbitos de la vida de los colores, lo cual a su vez permite considerar estos últimos como conceptualizaciones articuladas en pares de oposición o agrupamientos tripartitos.To gain greater insight into the color semantic field, it is important to consult various Mayance language dictionaries, in order to assemble a preliminary chromatic vocabulary, composed of five basic color terms which in Yucatec Maya are sak, ek', chak, k'an and ya'ax, or "white", "black", "red", "yellow" and "green-blue", respectively. The very vocabulary addresses certain extra-linguistic categories that language is capable of accumulating, reflecting, and communicating. These categories depend on a particular culture; consequently this study is amplified with greater information from different sources written during the colonial period in order to shed light on the many uses that the colors had in the aspects of human life which, at the same time, can be seen in conceptualizations articulated in pairs of opposition or tripartite groupings.

Population, Rural Development, and Land Use Among Settler Households in an Agricultural Frontier in Guatemala’s Maya Biosphere Reserve

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David Carr

2009-11-01

Full Text Available Guatemala was among the world’s leaders in deforestation during the 1990s at a rate of 2% per annum. Much of Guatemala’s recent forest loss has occurred in the emerging agricultural frontiers of the Maya Biosphere Reserve (MBR, the heart of the largest contiguous tropical forest in Central America—La Selva Maya. This paper presents data from 241 heads of households and 219 partners of household heads from a geographically stratified sample of eight (of 28 communities in the Sierra de Lacandón National Park (SLNP, the most ecologically biodiverse region in La Selva Maya and a core conservation zone of the MBR. Settler households are examined relative to a host of factors relating land use and land cover change. Specifically, demographic trends, political and socio-economic development, and ecological factors are described in this first detailed statistically-representative sample probing human population and environment interactions in an emerging agricultural frontier in Central America.

Characterization of karak clay from pakistan for pharmaceutical and cosmetic applications

International Nuclear Information System (INIS)

Shah, L.A.; Silva-Valenzuela, M.G.; Valenzuela-Diaz, F.R.; Sayeg, I.J.; Carvalho, F.M.S.

2012-01-01

Full text: Clay, the most important, plentiful, and low cost naturally occurring mineral, is widely used in variety of industrial application including Pharmaceutical and cosmetic. Clay is the fine grained aluminosilicate mineral which shows the property of plasticity at appropriate water content, and becomes hard upon drying. In Pakistan there are different types of clay but till now neither of them properly identified nor characterize for specific industrial application. The objective of this work is to characterize Karak clay for pharmaceutical and cosmetic applications collected from deposit located at Shagai region, District Karak, Pakistan. The clay was characterized through Xray diffractometry (XRD), X-ray Fluorescence (XRF), trace elemental Analysis, Microbiological analysis, Cation exchange capacity (CEC), pH and swelling assays according to European, United States of America and Brazilian Pharmacopeias. Bulk Chemical analysis shows that the Aluminum oxide and silica oxide are present in large quantity which was confirmed by XRD that this sample has montmorillonite as a major while illite and kaolinite as minor clay minerals. Quartz of small quantity was also found as a non-clay mineral. After analyzing the results for sample it was concluded that the clay is a strong candidate for cosmetic purposes. (author)

Population, Rural Development, and Land Use Among Settler Households in an Agricultural Frontier in Guatemala’s Maya Biosphere Reserve

OpenAIRE

David Carr

2009-01-01

Guatemala was among the world’s leaders in deforestation during the 1990s at a rate of 2% per annum. Much of Guatemala’s recent forest loss has occurred in the emerging agricultural frontiers of the Maya Biosphere Reserve (MBR), the heart of the largest contiguous tropical forest in Central America—La Selva Maya. This paper presents data from 241 heads of households and 219 partners of household heads from a geographically stratified sample of eight (of 28) communities in the Sierra de Lacan...

Análisis ambiental y económico de proyectos carreteros en la Selva Maya, un estudio a escala regional

DEFF Research Database (Denmark)

Conde, Dalia Amor; Burgués, Irene; Fleck, Leonardo

density of roads is one of the leading factors that have preserved the Maya Forest’s natural ecosystems. Decision-makers are confronted with an apparent conflict between conservation and development goals. In this study, we analyze the economic and environmental impacts of Maya Forest road projects...... the environmental impacts of the following road segments: Caobas-Tikal, San Andrés-Mirador, Mirador-Calakmul, Uaxactún-Mirador, Yaxhá-Nakum-Naranjo, Melchor de Mencos-Arrollo Negro, Lamanai –Border with Guatemala, El Ceibo-El Naranjo and Escárcega-Xpujil (Right-of-way within the Balam-kú y Calakmul reserves...... equity. In those cases where road projects are already under construction in the Maya Forest, measures are needed to minimize and offset deforestation and to maintain connectivity between natural habitats. This goal can be reached in part through investments in better protection of parks and reserves...

IMPRISONMENT AS A RESULT OF WOMEN SUBORDINATION 194 REFLECTED IN MAYA ANGELOU‘S POEMS

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Fatikha Amalina

2017-12-01

Full Text Available This research is aimed to describe the imprisonment of African American people, especially women, in the case of patriarchy and women subordination through Maya Angelou‘s selected poems entitled ―Caged Bird‖, ―Still I Rise‖ and ―Woman Work‖. This research discusses the meaning behind the poems that reflected Maya Angelou‘s life experience relating to women subordination and freedom. Feminism approach is applied to analyze the concept of freedom in women subordination and patriarchy in this research. The paper points to how the concept of gender intertwines with labor, ethnics, kinship and gender domination. Without aiming to paint a detailed picture of feminism, the paper explores how ideas developed in these inquiries question the taken-for-granted assumption about the universality of women‘s subordination and challenge the emancipation prerequisite of feminist agenda.

LA RELIGIOSIDAD MAYA- ACHI’ GUATEMALTECA COMO FUNDAMENTO DE SU IDENTIDAD CULTURAL

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David Caballero Mariscal

2017-12-01

Full Text Available En el contexto general de Guatemala, caracterizado por la diversidad étnica y cultural, y mayoritariamente indígena, los achi’es constituyen menos de uno por ciento de la población. Sin embargo, y a pesar de que han sufrido la imposición cultural de pueblos vecinos, de los españoles, y posteriormente, un atroz genocidio, continúan conservando parte de su patrimonio cultural intangible, manifestado en la lengua, las danzas, el Rabinal achi’,y diversas sus expresiones religiosas, que, sin duda, se constituyen en el garante de su identidad cultural. El presente artículo pretende llenar el vacío existente actualmente sobre la etnia achi’, ante la ausencia de estudios sobre ésta. De igual modo, trata de profundizar sobre los mecanismos adaptativos de sincretismo que se han desarrollado a nivel cultural y religioso como medio de supervivencia a través de nuevos modos de transculturación, que garantizan la pervivencia de la cultura y religiosidad maya tradicional en el contexto de la fe católica, vigente y mayoritaria entre los miembros de este pueblo maya.

Costa Oriental Maya: una acercamiento al comercio y navegación

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Iván Renato Zúñiga Carrasco

2014-01-01

Full Text Available La costa oriental de la Península de Yucatán ofreció un medio ideal para navegantes y mercaderes por la geografía costera peninsular cruzada por extensas redes fluviales que se extienden a lo largo de sus costas y se remontan lejanamente en el interior. E l intercambio de productos a través de largas distancias fue un factor básico en la homogeneidad cultural del mundo maya, jugando un papel crítico en el desarrollo de esta antigua civilización. El comercio marítimo maya se remonta al periodo Preclásico Ta rdío (300 a.C. - 300 d.C. Muchos puertos estaban ubicados en lugares estratégicos para el comercio, como islas, promontorios o a la entrada de ríos y en la mayoría de las veces se ubicaban en lugares protegidos del mar abierto. Las canoas utilizadas por los nativos no se trataba de simples troncos ahuecados; el uso de velas además y remos como puede verse en representaciones en murales y códices.

Clay Houses

Science.gov (United States)

Pedro, Cathy

2011-01-01

In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

Análisis ambiental y económico de proyectos carreteros en la Selva Maya, un estudio a escala regional

OpenAIRE

Conde, Dalia Amor; Burgués, Irene; Fleck, Leonardo; Manterola, Carlos; Reid, John

2007-01-01

Various road projects have been proposed in the border region of Mexico, Guatemala and Belize, which is part of the Maya Forest, the largest continuous forest in the Americas north of the Amazon. It is also part of the Mesoamerican biodiversity “hotspot,” one of the planet’s biologically richest zones. The Maya Forest is also known for its cultural and archeological riches, having been the cradle of Mayan civilization. The proposals for new road infrastructure are ostensibly aimed at spurring...

The systems containing clays and clay minerals from modified drug release: a review.

Science.gov (United States)

Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

2013-03-01

Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied. Copyright © 2012 Elsevier B.V. All rights reserved.

Gonad development during the early life of Octopus maya (Mollusca: Cephalopoda).

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Avila-Poveda, Omar Hernando; Colin-Flores, Rafael Francisco; Rosas, Carlos

2009-02-01

Gonad development during the early life of Octopus maya is described in terms of histological, morphometric, oocytes growth, and somatic-oocyte relationship data obtained from octopus cultured at the UMDI-UNAM, in Sisal, Yucatan, Mexico. This study is the first publication on gonad development during the early life of Octopus maya. A total of 83 O. maya specimens were used; their sizes ranged from 6.5 to 76 mm of total length (TL), 4 to 28 mm of dorsal mantle length (DML), 2.5 to 20 mm of ventral mantle length (VML), and 0.0180 to 7.2940 g of fixed body weight (fBW). Animals were weighed and measured only after preservation. A loss of 10% of living weight was estimated for juvenile octopuses after formalin preservation. The relation of length to weight (VML, DML, TL/fBW) pooled for both sexes had a strong positive correlation (r), as shown by a potential power function that was quite close to 1. Compound images were produced from numerous microscopic fields. The histological examination revealed that, 4 months after hatching, male octopus (24.5 mm DML and 7.2940 g fBW) were in gonad stages 2 (maturing) to 3 (mature), with spermatogonia and spermatocytes in the tubule wall and abundant spermatids and spermatozoa in the central lumen of the seminiferous tubules, suggesting the occurrence of different phases of gonad development at different maturity stages. In contrast, females (22.5 mm DML and 4.8210 g fBW) at the same time since hatching were immature (stage 1), with many oogonia, few oocytes, and germinal epithelium. This suggests that males reach maturity earlier than females, indicating a probable onset of maturity for males at around 4 months of culture or 8 g of wet body weight. Our results indicate the possibility that the size-at-weight can be recognized early with a degree of certainty that allows the sexes to be separated for culture purposes; but more detailed studies on reproduction in relation to endocrinology and nutrition are needed.

Story Starters on the Aztecs, Incas, and Mayas. A Creative Writing Program.

Science.gov (United States)

Henrich, Steve; Henrich, Jean

Designed to supplement an established language arts and social studies program, this books deals with the Aztecs, Incas, and Mayas of Latin America. All of the "Story Starter" books are intended to give a variety of vocabulary and story ideas to help with the writing process. Each of the books is divided into four main sections: (1) an…

Analysis of 16 autosomal STRs and 17 Y-STRs in an indigenous Maya population from Guatemala.

Science.gov (United States)

Cardoso, Sergio; Sevillano, Rubén; Illescas, María J; de Pancorbo, Marian Martínez

2016-03-01

The aim of this study was to contribute new data on autosomal STR and Y-STR markers of the Mayas from Guatemala in order to improve available databases of forensic interest. We analyzed 16 autosomal STR markers in a population sample of 155 indigenous Maya and 17 Y-chromosomal STR markers in the 100 males of the sample. Deviations from Hardy-Weinberg equilibrium and linkage disequilibrium between autosomal STR markers were not observed at any loci. The combined power of exclusion was estimated as 99.9991% and the combined power of discrimination was >99.999999999999%. Haplotype diversity of Y-STRs was calculated as 0.9984 ± 0.0018 and analysis of pairwise genetic distances (Rst) supported the Native American background of the population.

Psicología, subjetividad y cultura en el mundo Maya actual: una perspectiva crítica

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Jorge Mario Flores Osorio

2003-01-01

Full Text Available En la presente comunicación, después de hacer la crítica al concepto neo-colonial de Mesoamérica, se intenta demostrar que la subjetividad como espacio que contiene el fundamento del comportamiento psíquico, se construye como síntesis históricocolectiva y que en consecuencia demanda una racionalidad especial para su comprensión. Esa racionalidad se estudia en relación con una matriz piramidal, la cual es analizada. Asimismo, se considera que la concepción argumentada con base en el Pop Wuj o Libro del Tiempo Maya, puede permitir la conformación de una interpretación psicosocial consecuente con el espacio social y cultural de los Mayas en la actualidad

Utilization of crushed clay brick in cellular concrete production

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Ali A. Aliabdo

2014-03-01

Full Text Available The main objective of this research program is to study the effect of using crushed clay brick as an alternative aggregate in aerated concrete. Two series of mixtures were designed to investigate the physico-mechanical properties and micro-structural analysis of autoclave aerated concrete and foamed concrete, respectively. In each series, natural sand was replaced with crushed clay brick aggregate. In both series results showed a significant reduction in unit weight, thermal conductivity and sound attenuation coefficient while porosity has increased. Improvement on compressive strength of autoclave aerated concrete was observed at a percentage of 25% and 50% replacement, while in foamed concrete compressive strength gradually decreased by increasing crushed clay brick aggregate content. A comparatively uniform distribution of pore in case of foamed concrete with natural sand was observed by scanning electron microscope, while the pores were connected mostly and irregularly for mixes containing a percentage higher than 25% clay brick aggregate.

Incorporation, integration and irrigation at the ancient Maya site of Baking Pot, Belize

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James M. Conlon

1995-11-01

Full Text Available This paper provides an example of the use of corporate group analysis at the major ceremonial centre of Baking Pot, and uses comparative data from the site core of Baking Pot, other major centres in the upper Belize Valley, and various other sources throughout the Maya lowlands.

Forests, fields, and the edge of sustainability at the ancient Maya city of Tikal.

Science.gov (United States)

Lentz, David L; Dunning, Nicholas P; Scarborough, Vernon L; Magee, Kevin S; Thompson, Kim M; Weaver, Eric; Carr, Christopher; Terry, Richard E; Islebe, Gerald; Tankersley, Kenneth B; Grazioso Sierra, Liwy; Jones, John G; Buttles, Palma; Valdez, Fred; Ramos Hernandez, Carmen E

2014-12-30

Tikal has long been viewed as one of the leading polities of the ancient Maya realm, yet how the city was able to maintain its substantial population in the midst of a tropical forest environment has been a topic of unresolved debate among researchers for decades. We present ecological, paleoethnobotanical, hydraulic, remote sensing, edaphic, and isotopic evidence that reveals how the Late Classic Maya at Tikal practiced intensive forms of agriculture (including irrigation, terrace construction, arboriculture, household gardens, and short fallow swidden) coupled with carefully controlled agroforestry and a complex system of water retention and redistribution. Empirical evidence is presented to demonstrate that this assiduously managed anthropogenic ecosystem of the Classic period Maya was a landscape optimized in a way that provided sustenance to a relatively large population in a preindustrial, low-density urban community. This landscape productivity optimization, however, came with a heavy cost of reduced environmental resiliency and a complete reliance on consistent annual rainfall. Recent speleothem data collected from regional caves showed that persistent episodes of unusually low rainfall were prevalent in the mid-9th century A.D., a time period that coincides strikingly with the abandonment of Tikal and the erection of its last dated monument in A.D. 869. The intensified resource management strategy used at Tikal-already operating at the landscape's carrying capacity-ceased to provide adequate food, fuel, and drinking water for the Late Classic populace in the face of extended periods of drought. As a result, social disorder and abandonment ensued.

Las muchachas mayas de Yaxcabá, Yucatán

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Maya Lorena Pérez Ruiz

2017-01-01

Full Text Available El tema de este artículo es el significado de ser mujer y ser joven en la cultura maya de Yucatán, México. Se presentan testimonios de muchachas de bachillerato del pueblo de Yaxcabá con el objetivo de conocer lo que para ellas significa ser mujer joven. Sus percepciones y sus proyectos de futuro se enmarcan en un campo de conflicto, en el que existe un enfrentamiento entre jóvenes y adultos para mantener o transformar los significados y las prácticas de ser joven.

Condiciones alimentarias de los mayas macehuales de Quintana Roo

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Virginia Ivonne Sánchez Vázquez

2011-07-01

Full Text Available Las políticas alimentarias ofrecen una visión oficial sobre las condiciones de la alimentación en México, y específicamente en el México rural indígena, pero a partir de un estudio de caso con los grupos mayas macehuales de Quintana Roo, se muestra el contexto de confrontación donde las comunidades despliegan sus pautas de reproducción social, ciertamente en desventaja estructural, pero no de manera pasiva, sino creando y recreando opciones bajo su marco cultural situado.

Las muchachas mayas de Yaxcabá, Yucatán

OpenAIRE

Maya Lorena Pérez Ruiz

2017-01-01

El tema de este artículo es el significado de ser mujer y ser joven en la cultura maya de Yucatán, México. Se presentan testimonios de muchachas de bachillerato del pueblo de Yaxcabá con el objetivo de conocer lo que para ellas significa ser mujer joven. Sus percepciones y sus proyectos de futuro se enmarcan en un campo de conflicto, en el que existe un enfrentamiento entre jóvenes y adultos para mantener o transformar los significados y las prácticas de ser joven.

Standard Guide for Wet Sieve Analysis of Ceramic Whiteware Clays

CERN Document Server

American Society for Testing and Materials. Philadelphia

2007-01-01

1.1 This guide covers the wet sieve analysis of ceramic whiteware clays. This guide is intended for use in testing shipments of clay as well as for plant control tests. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Calm, Cool, and Comfortable in Clay

Science.gov (United States)

Stylianou, Xanthippi Cynthia

2010-01-01

The author's fourth-grade students had just finished a drawing unit that focused on the human figure. Projects included charcoal gesture drawings and chalk manikin drawings in chiaroscuro. She wanted to integrate a new medium for students to continue their study of the human figure. Since students are always excited to work with clay, making clay…

El proceso fonológico de elisión de la segunda vocal en el maya yucateco

OpenAIRE

Sobrino Gómez, Carlos Martín

2007-01-01

Como en otras lenguas del mundo, tales como el francés o el inglés, existen en maya yucateco fenómenos de reducción fonética. Este concepto se refiere a cualquier supresión de sonidos en una secuencia fónica que reduce el número de sílabas de la misma. Específicamente se estudia aquí en el maya yucateco la elisión de la segunda vocal en palabras trisilábicas. En este trabajo se presenta un breve pero importante análisis histórico de esta lengua en el cual observaremos un cambio fonético y gra...

Leveraging Social Networks to Support Reproductive Health and Economic Wellbeing among Guatemalan Maya Women

Science.gov (United States)

Prescott, Alexandra S.; Luippold-Roge, Genevieve P.; Gurman, Tilly A.

2016-01-01

Objective: Maya women in Guatemala are disproportionately affected by poverty and negative reproductive health outcomes. Although social networks are valued in many Indigenous cultures, few studies have explored whether health education programmes can leverage these networks to improve reproductive health and economic wellbeing. Design: This…

Elements of success in cooperatives conformed by Maya women in the Yucatan Peninsula, Mexico

NARCIS (Netherlands)

Osorio Vazqez, Maria Cristina; Bressers, Johannes T.A.; Franco Garcia, Maria Laura; Boer, C.L.; Reyes Maya, Oscar Ivan

2016-01-01

This paper describes different elements leading to the success of cooperatives formed by indigenous Maya women of the Yucatan Peninsula in Mexico. These elements have shown to facilitate the sustainability (permanence over time) of the cooperatives and their presence in the market, while improving

Ethnomedical research and review of Q'eqchi Maya women's reproductive health in the Lake Izabal region of Guatemala: Past, present and future prospects.

Science.gov (United States)

Michel, Joanna L; Caceres, Armando; Mahady, Gail B

2016-02-03

In Central America, most Maya women use ethnomedicines for all aspects of their reproductive cycle including menstruation, pregnancy and menopause. However, very few of these plants have been documented, collected and tested in appropriate pharmacological assays to determine possible safety and efficacy. The aim of this work was to provide an overview of information on the ethnomedical uses, ethnopharmacology, chemistry and pharmacological research for medicinal plants used for women's reproductive health in Guatemala, with a special emphasis on the Q'eqchi Maya of the Lake Izabal region, to demonstrate therapeutic potential and support future research in the field. Reviews of the ethnobotanical, ethnomedical and ethnopharmacological literature were performed for 30 plants collected in the Lake Izabal region of Guatemala and used by the Q'eqchi Maya for treatment of reproductive health issues were performed up to and including July 2015 using multiple databases, library searches for abstracts, books, dissertations, and websites. Review of the published research confirms that many of the plants used by Q'eqchi Maya women for the management of reproductive health issues have pharmacological activities, including analgesic, anti-inflammatory, estrogenic, progestagenic and/or serotonergic effects, that support the use of these plants and provide plausible mechanisms of action for their traditional uses. Furthermore, a new serotonin agonist, 9, 10-methylenedioxy-5, 6-Z-fadyenolide was isolated, thereby demonstrating an untapped potential for drug discovery. However, to date much of the pharmacological assays have been in vitro only, and few in vivo studies have been performed. Considering the large percentage of the Maya population in Guatemala that use traditional medicines, there remains a significant lack of pharmacological and toxicological data for these plants. Future research should focus on the safety and efficacy of medicinal plants using in vivo preclinical

Classic Maya civilization collapse related to modest reduction in precipitation

Science.gov (United States)

Medina-Elizalde, M.; Rohling, E. J.

2013-05-01

The disintegration of the Classic Maya civilization during the Terminal Classic Period (TCP) in the Yucatán Peninsula (YP) and Central America was a complex process that occurred over a ~200-year interval and involved a catastrophic depopulation of the region. While it is well established that the civilization collapse coincided with widespread episodes of drought, their nature and severity remain enigmatic. We present a quantitative analysis that offers a coherent interpretation for four of the most detailed paleoclimate records of the event. The underlying processes driving the patterns and amplitudes of these environmental records during the TCP are evaluated with an isotope mass balance model set up for Lake Chichancanab, located in the YP. We use our hydrological-isotope model (i) to test whether the TCP droughts reflect a persistent summer season southern shift of the intertropical convergence zone and its associated belt of convective activity, away from the YP, and (2) to simulate the development of Lake Chichancanab as a function of weaker perturbations to summer precipitation as reflected by a stalagmite d18O-derived rainfall record from the YP. We conclude that the droughts occurring during the disintegration of the Maya civilization represented up to 40% reduction in annual precipitation, likely due to a reduction in summer season tropical cyclone frequency/intensity. Archaeological and Paleoclimatic records from the Yucatan Peninsula

Jugadores de pelota maya en tiempos del oxlajuj b’ak’tún

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Jairzinho Francisco Panqueba Cifuentes

2012-12-01

Full Text Available La presente reflexión hace parte de un proceso investigativo cuyo objeto ha sido la práctica contemporánea del juego de pelota maya en Guatemala. Es un acercamiento analítico a los testimonios de vida recabados a través de la metodología de investigación-aprehendizaje compartida con los actores del proceso. Sus trayectorias vitales nos permiten comprender en descripciones y acciones, los detalles contemporáneos de una manifestación cultural, lúdica y recreativa ancestral. Pero también de qué maneras el juego de pelota mesoamericano es fuente de conocimientos de los patrimonios corporales hasta ahora difusos entre discursos relacionados con el folclor, las etnicidades, las artes, el deporte, la cultura, las espiritualidades y en general con ciencias como la historia, la antropología y la arqueología. Las vidas cotidianas de los actuales jugadores de pelota ayudan a comprender una parte de las sabidurías ancestrales mayas. Se integran, por tanto, a los testimonios de las herencias inmateriales arqueológicas representadas en los campos de juego de pelota diseminados por Mesoamérica.

Beyond Nature Appropriation: Towards Post-development Conservation in the Maya Forest

OpenAIRE

Jose E Martinez-Reyes

2014-01-01

The establishment of biosphere reserves in Mexico was followed by alternative livelihood conservation/development projects to integrate indigenous groups into Western style conservation under the idea of sustainable development and participation. In this paper, I discuss the outcomes of two forest wildlife management projects in one Maya community along the Sian Ka′an Biosphere Reserve in the state of Quintana Roo. Both projects ultimately failed and the community mobilised and expelled the N...

Population dynamics and stock assessment for Octopus maya (Cephalopoda:Octopodidae fishery in the Campeche Bank, Gulf of Mexico

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Francisco Arreguín-Sánchez

2000-06-01

Full Text Available The octopus (Octopus maya is one of the most important fish resources in the Mexican Gulf of Mexico with a mean annual yield of 9000 ton, and a reasonable number of jobs created; O. maya represents 80% of the total octopus catch, followed by Octopus vulgaris. There are two artisanal fleets based on Octopus maya and a middle-size fleet that covers both species. Catch-at-length structured data from the artisanal fleets, for the 1994 season (August 1st to December 15th were used to analyze the O. maya population dynamics and stock and to estimate the current level of exploitation. Von Bertalanffy growth parameters were: L = 252 mm, mantle length; K=1.4 year -1; oscillation parameters C=1.0, WP=0.6; and tz=0.842 years. A rough estimate of natural mortality was M=2.2, total mortality from catch curve Z=8.77, and exploitation rate F/Z=0.75. This last value suggests an intensive exploitation, even when yield per recruit analysis indicates both fleets may increase the minimum legal size on about 10% to increase yields. The length-based VPA also shows that the stock is being exploited under its maximum acceptable biological limit. These apparently contradictory results are explained by biological and behavioral characteristics of this species. Because most females die after reproduction, a new gross estimation of natural mortality was computed as M=3.3. The new estimate of exploitation rate was F/Z=0.57. This new value coincides with results from the length-VPA and the Thompson and Bell methods, the former suggesting that a reduction of 20% in fishing mortality may provide larger yields. This fishery resource is fully exploited and current management measures must be revised to sustain and probably optimize yields.Octopus maya es uno de los recursos pesqueros más importantes del Golfo de México, con rendimientos anuales promedio de 9 000 t, y constituye el 80% de la captura total, seguido por O. vulgaris. En la pesquería participan dos flotas

The nature of porosity in organic-rich mudstones of the Upper Jurassic Kimmeridge Clay Formation, North Sea, offshore United Kingdom

Science.gov (United States)

Fishman, Neil S.; Hackley, Paul C.; Lowers, Heather; Hill, Ronald J.; Egenhoff, Sven O.; Eberl, Dennis D.; Blum, Alex E.

2012-01-01

Analyses of organic-rich mudstones from wells that penetrated the Upper Jurassic Kimmeridge Clay Formation, offshore United Kingdom, were performed to evaluate the nature of both organic and inorganic rock constituents and their relation to porosity in this world-class source rock. The formation is at varying levels of thermal maturity, ranging from immature in the shallowest core samples to mature in the deepest core samples. The intent of this study was to evaluate porosity as a function of both organic macerals and thermal maturity. At least four distinct types of organic macerals were observed in petrographic and SEM analyses and they all were present across the study area. The macerals include, in decreasing abundance: 1) bituminite admixed with clays; 2) elongate lamellar masses (alginite or bituminite) with small quartz, feldspar, and clay entrained within it; 3) terrestrial (vitrinite, fusinite, semifusinite) grains; and 4) Tasmanites microfossils. Although pores in all maceral types were observed on ion-milled surfaces of all samples, the pores (largely nanopores with some micropores) vary as a function of maceral type. Importantly, pores in the macerals do not vary systematically as a function of thermal maturity, insofar as organic pores are of similar size and shape in both the immature and mature Kimmeridge rocks. If any organic pores developed during the generation of hydrocarbons, they were apparently not preserved, possibly because of the highly ductile nature of much of the rock constituents of Kimmeridge mudstones (clays and organic material). Inorganic pores (largely micropores with some nanopores) have been observed in all Kimmeridge mudstones. These pores, particularly interparticle (i.e., between clay platelets), and intraparticle (i.e., in framboidal pyrite, in partially dissolved detrital K-feldspar, and in both detrital and authigenic dolomite) are noteworthy because they compose much of the observable porosity in the shales in both

Early Middle Formative Occupation in the Central Maya Lowlands: Recent Evidence from Cahal Pech, Belize

Directory of Open Access Journals (Sweden)

Jaime Awe

1990-11-01

Full Text Available After more than half a century of intensive archaeological research the early Middle Formative (or Middle Preclassic period (1000-600 B.C. continues to be one of the most enigmatic eras in the study of Lowland Maya prehistory. While several factors contribte to this situation, the primary cause for this obscurity lies in the fact that few sites have produced either contextual or stratigraphic evidence of occupation during this phase (Rice 1976; Andrews 1988. Concsequently, any new site with evidence of Middle Formative occupation can contribute substantially to our limited knowledge of this pioneering stage of the lowland Maya. This paper introduces one such site, Cahal Pech, where recent investigations have uncovered a stratigraphic sequence that tentatively spans the early Middle Formative to the Late Classic period. It provides a preliminary description, of the site's early Middle Formative configuration and briefly discusses its possible regional affiliation.

76 FR 12786 - Culturally Significant Objects Imported for Exhibition Determinations: “Poetry in Clay: Korean...

Science.gov (United States)

2011-03-08

... Determinations: ``Poetry in Clay: Korean Buncheong Ceramics from the Leeum, Samsung Museum of Art'' SUMMARY... in Clay: Korean Buncheong Ceramics from the Leeum, Samsung Museum of Art,'' imported from abroad for temporary exhibition within the United States, are of cultural significance. The objects are imported...

A review of WIPP [Waste Isolation Pilot Plant] repository clays and their relationship to clays of adjacent strata

International Nuclear Information System (INIS)

Krumhansl, J.L.; Kimball, K.M.; Stein, C.L.

1990-12-01

The Salado Formation is a thick evaporite sequence located in the Permian Delaware Basin of southeastern New Mexico. This study focuses on the intense diagenetic alteration that has affected the small amounts of clay, feldspar, and quartz washed into the basin during salt deposition. These changes are of more than academic interest since this formation also houses the WIPP (Waste Isolation Pilot Plant). Site characterization concerns warrant compiling a detailed data base describing the clays in and around the facility horizon. An extensive sampling effort was undertaken to address these programmatic issues as well as to provide additional insight regarding diagenetic mechanisms in the Salado. Seventy-five samples were collected from argillaceous partings in halite at the stratigraphic level of the Waste Isolation Pilot Plant (WIPP). These were compared with twenty-eight samples from cores of the Vaca Triste member of the Salado, a thin clastic unit at the top of the McNutt potash zone, and with a clay-rich sample from the lower contact of the Culebra Dolomite (in the overlying Rustler Formation). These settings were compared to assess the influence of differences in brine chemistry (i.e., halite and potash facies, normal to hypersaline marine conditions) and sediment composition (clays, sandy silt, dolomitized limestone) on diagenetic processes. 44 refs., 11 figs., 5 tabs

Comprehensive review of geosynthetic clay liner and compacted clay liner

Science.gov (United States)

Shankar, M. Uma; Muthukumar, M.

2017-11-01

Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

OpenAIRE

Schjønning, P.; de Jonge, L.W.; Munkholm, L.J.; Moldrup, P.; Christensen, B.T.; Olesen, J.E.

2011-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

Los usos sociales de la matemática en las ciencias prácticas de la cultura maya: un estudio socioepistemológico

OpenAIRE

Cantoral, Ricardo; Covián, Olda

2005-01-01

El presente trabajo plantea el estudio del conocimiento matemático de la cultura maya desde la aproximación socioepistemológica, ya que se aporta una visión diferente de las que suelen abordarse en la literatura: antropológica o etnográfica entre otras. Se plantea el estudio de prácticas sociales que se encuentran en la cultura maya y que son a la vez generadoras de conocimiento matemático.

Apicultura y organizaciones de apicultores entre los mayas de Yucatán Beekeeping and Apicultural Organizations Among the Mayas of Yucatan

Directory of Open Access Journals (Sweden)

Margarita Rosales González

2010-01-01

Full Text Available En las comunidades mayas la apicultura continúa siendo una actividad relevante pero complementaria, cuya lógica y condiciones de producción se contraponen a las nuevas normas del mercado internacional. La integración de organizaciones apícolas se considera una estrategia para la "modernización" de la apicultura y la comercialización de la miel en mejores condiciones. Este trabajo se refiere al sentido que tanto la apicultura como estas organizaciones tienen para sus integrantes, a sus expectativas, intereses, aprendizajes y a la forma en que se relacionan con instituciones y agentes externos. El escrito se basa en entrevistas y observaciones realizadas en 12 organizaciones apícolas durante 2005 y 2006 en el marco del proyecto de investigación del centro INAH Yucatán "Organizaciones indígenas y procesos de desarrollo en comunidades mayas del sur de Yucatán".In Mayan communities, beekeeping continues to be an important but complementary activity, whose logic and conditions of production are opposed to the new norms of the international market. The integration of apicultural organizations is considered as a strategy for the "modernization" of beekeeping and the commercialization of the honey in better quality. The present research deals with the meaning that beekeeping has for the members of such organizations, and it explores the expectations, interests and training processes of the members, analyzing finally how are the relationships between these organizations and external agents and institutions. The research is based on interviews and observations made in 12 apicultural organizations between 2005 and 2006, as part of the research project of the INAH Regional Center Yucatan, entitled "Indigenous Organizations and Processes of Development in Mayan Communities in Southern Yucatan".

Volcanic ash in ancient Maya ceramics of the limestone lowlands: implications for prehistoric volcanic activity in the Guatemala highlands

Science.gov (United States)

Ford, Anabel; Rose, William I.

1995-07-01

In the spirit of collaborative research, Glicken and Ford embarked on the problem of identifying the source of volcanic ash used as temper in prehistoric Maya ceramics. Verification of the presence of glass shards and associated volcanic mineralogy in thin sections of Maya ceramics was straightforward and pointed to the Guatemala Highland volcanic chain. Considering seasonal wind rose patterns, target volcanoes include those from the area west of and including Guatemala City. Joint field research conducted in 1983 by Glicken and Ford in the limestone lowlands of Belize and neighboring Guatemala, 300 km north of the volcanic zone and 150 km from the nearest identified ash deposits, was unsuccessful in discovering local volcanic ash deposits. The abundance of the ash in common Maya ceramic vessels coupled with the difficulties of long-distance procurement without draft animals lead Glicken to suggest that ashfall into the lowlands would most parsimoniously explain prehistoric procurement; it literally dropped into their hands. A major archaeological problem with this explanation is that the use of volcanic ash occurring over several centuries of the Late Classic Period (ca. 600-900 AD). To accept the ashfall hypothesis for ancient Maya volcanic ash procurement, one would have to demonstrate a long span of consistent volcanic activity in the Guatemala Highlands for the last half of the first millennium AD. Should this be documented through careful petrographic, microprobe and tephrachronological studies, a number of related archaeological phenomena would be explained. In addition, the proposed model of volcanic activity has implications for understanding volcanism and potential volcanic hazards in Central America over a significantly longer time span than the historic period. These avenues are explored and a call for further collaborative research of this interdisciplinary problem is extended in this paper.

Levels of persistent organic pollutants in breast milk of Maya women in Yucatan, Mexico.

Science.gov (United States)

Polanco Rodríguez, Ángel G; Inmaculada Riba López, M; Angel DelValls Casillas, T; León, Jesús Alfredo Araujo; Anjan Kumar Prusty, B; Álvarez Cervera, Fernando J

2017-02-01

In this study, 24 breast milk samples, obtained from rural Maya women, from municipalities of Yucatan, Mexico, were analyzed for organochlorine pesticide (OCP) residues by gas chromatography. Recent studies have shown that Maya communities have a poor perception about the proper usage and handling of OCP. The karstic soil in this area has a high vulnerability to groundwater pollution by the use of OCP in agriculture and livestock activities. The impact of the ecosystem on human health is much more critical due to the prevailing poverty and a very low educational level of these communities. About 30% of the Maya population consumes water directly from contaminated wells and sinkholes, resulting in a chronic exposure to OCP. The samples served to identify and quantify high levels of OCP residues (18.43 mg/kg of heptachlor epoxide and 1.92 mg/kg of endrin in the metropolitan zone; 2.10 mg/kg of dieldrin, 0.117 mg/kg of endosulfan II, 0.103 mg/kg of heptachlor, 0.178 mg/kg of endrin, and 0.127 mg/kg of endrin aldehyde in the main agricultural zone and on the west coast). The detected levels of OCP residues are a major concern and represent a potential risk to women and children in the region. This could be associated with the high rates of cervical uterine and breast cancer mortality in Yucatan. Thus, regulations on the usage of OCP and their enforcement are necessary, and it is important to establish a yearly monitoring program for OCP residues in breast milk and groundwater, as well as to implement health promotion programs for women in particular and the general population in general.

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

Science.gov (United States)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Clay and Anxiety Reduction: A One-Group, Pretest/Posttest Design with Patients on a Psychiatric Unit

Science.gov (United States)

Kimport, Elizabeth R.; Hartzell, Elizabeth

2015-01-01

Little research exists on using clay as an anxiety-reducing intervention with patients in psychiatric hospitals. This article reports on a study that used a one-group, pretest/posttest design with 49 adults in a psychiatric facility who created a clay pinch pot. The State-Trait Anxiety Inventory (STAI) was used as a pre- and posttest measure.…

The Territory of Quintana Roo. Colo­nization and Military Control Attempts in the Selva Maya (1888-1902

Directory of Open Access Journals (Sweden)

Carlos Macías Richard

1999-07-01

Full Text Available The  federal territory of Quintana Roo was established in 1902, shortly after federal forces, under General Ignacio A. Bravo, concluded a long and intense campaign against one of the country's oldest rebel groups: the Maya from the Selva Oriental of the Yucatan Península. This article analyzes the successive military attempts to finally overtake the Maya sanctuary Chan Santa Cruz, where the Speaking Cross is located, which occurred within the wider central attempts to colonize the  peninsula. Furthermore, the arti­cle includes and makes a contextual interpretation of  the individual profiles  of  the  last campaign's leaders, in order to explain the "militarized" beginnings of  the  Quintana Roo government.

Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

International Nuclear Information System (INIS)

Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

2005-01-01

Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

Clay Dispersibility and Soil Friability-Testing the Soil Clay-to-Carbon Saturation Concept

DEFF Research Database (Denmark)

Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl

2012-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

Does the Maya Forest Need More Roads?:Conservation Policy in Brief

OpenAIRE

Conde, Dalia Amor; Ramos, Victor Hugo; Burgués, Irene; Castellanos, Bayron; Fleck, Leonardo; Albacete, Carlos; Espinoza, Piedad; Manterola, Carlos; Paiz, Gerardo

2007-01-01

An assortment of road projects has been proposed in the border region of Mexico, Guatemala and Belize, which is part of the Maya Forest, the largest contiguous tropical forest in the Americas north of the Amazon. The proposals are apparently aimed at spurring economic growth and reducing the high levels of poverty found in this area. But more and better roads usually bring more people and expand farms. Decision-makers are therefore confronted with a seeming conflict between conservation and d...

La violencia sexual como genocidio. Memoria de las mujeres mayas sobrevivientes de violación sexual durante el conflicto armado en Guatemala

OpenAIRE

Amandine Fulchiron

2016-01-01

Este art culo es producto de la investigaci n/ acci n participativa llevada a cabo del 2005 al 2009 en el marco del proceso pol tico y social impulsado por Actoras de Cambio junto con 54 mujeres mayas de cuatro grupos tnicos distintos ?Q eqchi , Mam, Chuj, y Kaqchikel? sobrevivientes de violaci n sexual durante el con icto armado interno en Guatemala (1960-1996). En l analizamos el uso sistem tico y masivo de la violaci n sexual contra las mujeres mayas dentro del marco de la pol tica contr...

SBR Brazilian organophilic/clay nanocomposites

International Nuclear Information System (INIS)

Guimaraes, Thiago R.; Valenzuela-Diaz, Francisco R.; Morales, Ana Rita; Paiva, Lucilene B.

2009-01-01

The aim of this work is the obtaining of SBR composites using a Brazilian raw bentonite and the same bentonite treated with an organic salt. The clays were characterized by XRD. The clay addition in the composites was 10 pcr. The composites were characterized by XRD and had measured theirs tension strength (TS). The composite with Brazilian treated clay showed TS 233% higher than a composite with no clay, 133% higher than a composite with Cloisite 30B organophilic clay and 17% lower than a composite with Cloisite 20 A organophilic clay. XRD and TS data evidence that the composite with Brazilian treated clay is an intercalated nanocomposite. (author)

Intelectuales Indígenas y Literaturas en México. El campo literario entre los zapotecas y los mayas

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Luz Maria Lepe Lira

2017-08-01

Full Text Available Este artículo explora la conformación del campo intelectual en la literatura zapoteca del istmo de Tehuantepec y la literatura maya de la Península de Yucatán. A través del concepto de campo intelectual de Pierre Bordieu (2002 y bajo la premisa de que hay tantos campos literarios como literaturas indígenas, se evidencia que estos espacios de poder simbólico están condicionados por elementos socioculturales y políticos que van desde la alfabetización y uso de la escritura en las lenguas indígenas hasta la función de los intelectuales en las redes locales y nacionales. En la literatura zapoteca se indican las estrategias de la generación de Andrés Henestrosa, la relación entre la COCEI y la Casa de Cultura de Juchitán, y los vínculos que sostienen los intelectuales de la región con otros intelectuales de la esfera nacional. Para la literatura maya yucateca se reflexiona sobre la generación de talleres literarios como el principal motor de la nueva literatura maya, tanto desde las instancias gubernamentales como desde las asociaciones civiles y grupos gestionados por los intelectuales mayas. Palabras- clave: intelectuales indígenas, campo intelectual, literatura zapoteca, literatura maya Indigenous Intellectuals and Literatures in Mexico. The Literary Field Between the Zapotecs and the Maya Abstract The present paper explores the conformation of the intellectual field in the Zapotec literature of the Istmhus of Tehuantepec and in the Mayan literature of the Yucatán Peninsula. Through the concept of intellectual field by Pierre Bordieu (2002 and under the premise that there are as many literary fields as indigenous literatures, this paper emphasizes the fact that these spaces of symbolic power and conditioned by sociocultural and political elements ranging from literacy and the use of writing in indigenous languages to the role of intellectuals in local and national networks. In the case of the Zapotec literature the focus lies

Construction of clay sealings for dumping of brown coal ash and residues from gas desulfurization units. Herstellung von Tonabdichtungen zur Deponierung von Braunkohleaschen und REA-Rueckstaenden

Energy Technology Data Exchange (ETDEWEB)

Kortmann, W

1989-07-01

With the putting into operation of flue gas scrubbers at the brown coal-fired power stations of the RWE not only 5 to 6 Mt conventional power station ash but also up to 2 Mt gypsum and water from the flue gas desulphurisation units are obtained annually, and these residues together with the ash are tipped on mixed dumps. These dumps are enclosed on all sides by a mineral sealing of clay with a thickness of at least 0.6 m. In keeping with the detailed plans for the construction and operation of mixed dumps as submitted to the competent authorities for approval, the sealing must have a permeability of K < 5x10{sup -10} m/s for the dump base and of K < 1x10{sup -10} m/s for the cover of the dump. In order to meet these high quality requirements the clay, which is obtained by opencast working with the aid of bucket wheel excavators, must first of all be crushed for construction of the sealings. In addition to the crushing of the clay to as small a lump size as possible, the adjustment of the correct sealing moisture content of the clay is of primary importance. Conditioning of the clay is effected in the conventional way by means of a pulvimixer, but also by means of a processing plant in pilot operation in the construction of clay sealings for dumps. With the aid of the processing plant clay of a high homogenisation grade is constantly available for sealing construction. The clay is spread on the base and slopes of the dump layer by layer with the aid of scraper dozers, each layer having a compacted thickness of about 20 cm. Compaction of the sealing layers is effected by heavy rammer butt rollers. In the case of highly plastic earth materials of the type used here in the construction of dumps the weight of the compacting roller and also the shape of the rammer butt are of importance. Compaction in the 1:2.5 steep dump slopes by means of a detachable roller steered by a cable has proved very satisfactory.

Atrazine biodegradation modulated by clays and clay/humic acid complexes

International Nuclear Information System (INIS)

Besse-Hoggan, Pascale; Alekseeva, Tatiana; Sancelme, Martine; Delort, Anne-Marie; Forano, Claude

2009-01-01

The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

Science.gov (United States)

Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

2017-08-11

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

Los conjuntos palaciegos reales de las Tierras Bajas Mayas del sur: una evaluación de los datos arqueológicos e iconográficos Royal palace complexes in Southern Maya Lowlands: evaluating archaeological and iconographical data

Directory of Open Access Journals (Sweden)

Kai Delvendahl

2010-01-01

Full Text Available Este artículo va a trazar algunas conclusiones de una evaluación de los aspectos físicos, espaciales, funcionales y sociales de los conjuntos palaciegos reales tomando en cuenta evidencia arqueológica e iconográfica. Para el componente iconográfico se analizaron representaciones de escenas palaciegas pintadas sobre 87 vasijas cilíndricas de cerámica, mientras que para el componente arqueológico se evaluó información de conjuntos palaciegos bien documentados como el Grupo Palaciego M7 de Aguateca, el Palacio de Palenque, Los 27 Escalones de Kohunlich, el Grupo 10L-2 de Copán, la Acrópolis Central de Tikal y el Grupo Gran Acrópolis de Calakmul. Uno de los objetivos generales de este trabajo es proporcionar un ejemplo de cómo se puede capitalizar la información que las escenas palaciegas proveen (al comparar el corpus iconográfico con el dato arqueológico. Esto permitiría plantear ideas más ajustadas sobre los aspectos físicos, espaciales, funcionales y sociales de los conjuntos palaciegos del Clásico Tardío en el área maya.This paper will present some conclusions of an evaluation of the physical, spatial, functional, and social aspects of Classic Maya royal palaces taking into account archaeological and iconographic evidence. For the iconographic evaluation, the analysis examined representations of palace-like ambience on 87 cylindrical ceramic vases, while the archaeological information includes data from the better documented palace groups of the Southern Maya Lowlands, including the Palace Group M7 of Aguateca, the Palace of Palenque, Los 27 Escalones of Kohunlich, Group 10L-2 of Copan, the Central Acropolis of Tikal and the Grand Acropolis Group of Calakmul. In comparing the iconographic corpus with the archaeological evidence, one of the general objectives of this presentation is to provide an example of how the information inherent in the palace scenes can be capitalized to propose more adjusted ideas about the

Support to other nuclear waste disposal programmes considering clay as a potential host rock

International Nuclear Information System (INIS)

Volckaert, G.

2009-01-01

SCK-CEN started to study the Boom Clay as potential host rock for nuclear waste disposal in 1974. Since then, SCK-CEN has been involved in other international projects studying clay as potential host rock in order to get a broader support for disposal in clay and to acquire broader insight in clay behaviour. Besides Belgium, France and Switzerland are currently investigating clay formations as potential host rock for the disposal of radioactive waste. In the Netherlands, clay formations have always been considered as an alternative to disposal in salt. The general interest in clays is increasing: in Germany and The United Kingdom, it was decided a few years ago that besides respectively salt and crystalline rock also clays need to be evaluated. In Eastern and Central Europe, the Slovak republic and Lithuania consider both clay and granite as possible host rocks for spent fuel while in Russia recently a project was started to study the possible disposal of low and medium level waste in a clay formation in the Leningrad area. Within the EC research and development framework programs and the OECD/NEA Clay Club, collaborations were developed between countries studying clay and with a strong involvement of SCK-CEN. The collaboration with the Eastern and Central European countries is supported through the support programme of the Belgian Ministry of Economic affairs. The objectives of these co-operations are to deliver expert services to other nuclear waste disposal programs considering clay as host rock; to to acquire broader international recognition of our expertise and support for the development of nuclear waste disposal in clay; to get a broader insight in the properties and behaviour of clays

Phosphonium modified clay/polyimide nanocomposites

International Nuclear Information System (INIS)

Ceylan, Hatice; Çakmakçi, Emrah; Beyler-Çiǧil, Asli; Kahraman, Memet Vezir

2014-01-01

In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA)

Development of sedentary communities in the Maya lowlands: coexisting mobile groups and public ceremonies at Ceibal, Guatemala.

Science.gov (United States)

Inomata, Takeshi; MacLellan, Jessica; Triadan, Daniela; Munson, Jessica; Burham, Melissa; Aoyama, Kazuo; Nasu, Hiroo; Pinzón, Flory; Yonenobu, Hitoshi

2015-04-07

Our archaeological investigations at Ceibal, a lowland Maya site located in the Pasión region, documented that a formal ceremonial complex was built around 950 B.C. at the onset of the Middle Preclassic period, when ceramics began to be used in the Maya lowlands. Our refined chronology allowed us to trace the subsequent social changes in a resolution that had not been possible before. Many residents of Ceibal appear to have remained relatively mobile during the following centuries, living in ephemeral post-in-ground structures and frequently changing their residential localities. In other parts of the Pasión region, there may have existed more mobile populations who maintained the traditional lifestyle of the preceramic period. Although the emerging elite of Ceibal began to live in a substantial residential complex by 700 B.C., advanced sedentism with durable residences rebuilt in the same locations and burials placed under house floors was not adopted in most residential areas until 500 B.C., and did not become common until 300 B.C. or the Late Preclassic period. During the Middle Preclassic period, substantial formal ceremonial complexes appear to have been built only at a small number of important communities in the Maya lowlands, and groups with different levels of sedentism probably gathered for their constructions and for public rituals held in them. These collaborative activities likely played a central role in socially integrating diverse groups with different lifestyles and, eventually, in developing fully established sedentary communities.

High-precision radiocarbon dating of political collapse and dynastic origins at the Maya site of Ceibal, Guatemala.

Science.gov (United States)

Inomata, Takeshi; Triadan, Daniela; MacLellan, Jessica; Burham, Melissa; Aoyama, Kazuo; Palomo, Juan Manuel; Yonenobu, Hitoshi; Pinzón, Flory; Nasu, Hiroo

2017-02-07

The lowland Maya site of Ceibal, Guatemala, had a long history of occupation, spanning from the Middle Preclassic Period through the Terminal Classic (1000 BC to AD 950). The Ceibal-Petexbatun Archaeological Project has been conducting archaeological investigations at this site since 2005 and has obtained 154 radiocarbon dates, which represent the largest collection of radiocarbon assays from a single Maya site. The Bayesian analysis of these dates, combined with a detailed study of ceramics, allowed us to develop a high-precision chronology for Ceibal. Through this chronology, we traced the trajectories of the Preclassic collapse around AD 150-300 and the Classic collapse around AD 800-950, revealing similar patterns in the two cases. Social instability started with the intensification of warfare around 75 BC and AD 735, respectively, followed by the fall of multiple centers across the Maya lowlands around AD 150 and 810. The population of Ceibal persisted for some time in both cases, but the center eventually experienced major decline around AD 300 and 900. Despite these similarities in their diachronic trajectories, the outcomes of these collapses were different, with the former associated with the development of dynasties centered on divine rulership and the latter leading to their downfalls. The Ceibal dynasty emerged during the period of low population after the Preclassic collapse, suggesting that this dynasty was placed under the influence from, or by the direct intervention of, an external power.

EL COLAPSO DEL CLÁSICO TARDÍO ENTRE LOS MAYAS DE UAXACTÚN (GUATEMALA Y BARTON RAMIE (BELICE SEGÚN EL REGISTRO FUNERARIO (The Late Classic Collapse among the Maya of Uaxactun, Guatemala and Barton Ramie, Belize according to the Mortuary Record

Directory of Open Access Journals (Sweden)

Pascual Izquierdo-Egea

2015-09-01

Full Text Available La aplicación del método de valoración contextual al análisis del registro funerario de Uaxactún (Guatemala y Barton Ramie (Belice aporta evidencias irrefutables sobre la huella material del colapso clásico en las ofrendas de los entierros mayas. Esto confirma lo que ya se había anticipado al estudiar la cuenca del río Balsas en México (2014. ENGLISH: Application of the contextual valuation method to the mortuary analysis of Uaxactun, Guatemala and Barton Ramie, Belize provides irrefutable evidence on the Classic Maya collapse recorded in the grave goods of these burials. This confirms what was already anticipated by studying the Balsas River basin in Mexico.

Rare earth elements distribution in clay zones of sedimentary formation, Pondicherry, south India

International Nuclear Information System (INIS)

Tirumalesh, K.; Gursharan Singh

2012-01-01

Concentrations of five rare earth elements (REE) were measured in clay samples of a deep bore hole comprising major aquifers of Pondicherry region, south India in order to investigate the geochemical variations among various litho-units. Clay samples from Cretaceous formation show distinct gray to black color whereas Tertiary deposits have clays with color varying from pale yellow to brown to gray. All measured REEs exhibit lower concentrations than Upper Continental Crust (UCC) average values. Large variations in REEs contents were observed in different sedimentary formations (Tertiary and Cretaceous). Chondrite normalized ratio of La/Lu and Eu/Eu* indicate that the clays are derived from weathering of felsic rock and possibly under humid climate. All the samples showed positive Eu anomaly in North American Shale Composite (NASC) normalized plot which shows plagioclase feldspar as the major contributor to these clays. Positive Eu anomaly is also an indication of reduced condition of the formation. (author)

Integrity of clay till aquitards to DNAPL migration: Assessment using current and emerging characterization tools

DEFF Research Database (Denmark)

Fjordbøge, Annika Sidelmann; Janniche, Gry Sander; Jørgensen, Torben H.

2017-01-01

Field investigations were carried out to determine the occurrence of tetrachloroethene (PCE) dense non-aqueous phase liquid (DNAPL), the source zone architecture and the aquitard integrity at a 30-50 year old DNAPL release site. The DNAPL source zone is located in the clay till unit overlying......% of the total PCE mass. The data set, and associated data analysis, supported vertical migration of DNAPL through fractures in the upper part of the clay till, horizontal migration along high permeability features around the redox boundary in the clay till, and to some extent vertical migration through...... the fractures in the reduced part of the clay till aquitard to the underlying limestone aquifer. The aquitard integrity to DNAPL migration was found to be compromised at a thickness of reduced clay till of less than 2 m....

Common clay and shale

Science.gov (United States)

Virta, R.L.

2000-01-01

Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

Combined hydrogen and carbon isotopes of plant waxes as an indicator of drought impacts on ancient Maya agriculture

Science.gov (United States)

Douglas, P. M.; Pagani, M.; Eglinton, T. I.; Brenner, M.; Hodell, D. A.; Curtis, J. H.

2012-12-01

There is increasing evidence suggesting that a series of droughts in the Yucatan Peninsula coincided with the Terminal Classic decline of the Classic Maya civilization (ca. 1250 to 1000 years BP). However, there is little evidence directly linking climatic change and changes in human activities in this region. In this study we combine plant-wax δD, δ13C, and Δ14C analyses in two lake sediment cores from southeastern Mexico and northern Guatemala to develop coupled records of hydroclimate variability and human-driven vegetation change. Plant-wax specific Δ14C ages indicate a large input of pre-aged plant waxes into lake sediment. Comparison of plant-wax δD records with other regional hydroclimate proxy records suggest that plant-wax ages are evenly distributed around plant-wax radiocarbon ages, and that applying an age model based on plant-wax radiocarbon ages is appropriate for these lake sediments. We evaluate how differences in plant-wax age distributions influence stable isotope records to assess the age uncertainty associated with records of climate and vegetation change derived from plant-wax stable isotopes. In this low-elevation tropical environment plant-wax δ13C is largely controlled by the relative abundance of C3 and C4 plants. The ancient Maya practiced widespread maize (C4) agriculture and strongly influenced regional C3-C4 vegetation dynamics. Under natural conditions C4 plant coverage and plant-wax δ13C would tend to co-vary positively since C4 plants are well adapted for dry conditions. Under ancient Maya land-use, however, this relationship is likely to be decoupled, since drought would have disrupted C4 agriculture. Combined analysis of plant-wax δD and δ13C from both lakes indicates increasingly divergent trends following ca. 3500 years BP, around the onset of widespread ancient Maya agriculture. After this time high plant-wax δD values tend to correspond with low plant-wax δ13C values and vice versa. This pattern is consistent with

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

International Nuclear Information System (INIS)

Tsai, Tsung-Yen; Lin, Mei-Ju; Chuang, Yi-Chen; Chou, Po-Chiang

2013-01-01

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O 2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites. - Highlights: ► We control the dispersion morphology by protonation of K2 into the clay. ► The CL120 and CL88, with the higher CEC, are more random intercalated by K2. ► We report these materials have good optical clarity, and UV resistance

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

Science.gov (United States)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

Science.gov (United States)

Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

2018-03-01

Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thixotropic Properties of Latvian Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

2015-01-01

This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

222Rn and CO2 soil-gas geochemical characterization of thermally altered clays at Orciatico (Tuscany, Central Italy)

International Nuclear Information System (INIS)

Voltattorni, N.; Lombardi, S.; Rizzo, S.

2010-01-01

Research highlights: → Soil-gas technique is applied to study gas permeability of Orciatico clay units. → Clay permeability depends on thermal and mechanical alteration degree. → Soil-gas distributions are due to shallow fracturing of clays. → Rn and CO 2 soil-gas anomalies highlight secondary permeability in clay sequence. → Soil-gas results are supported by detailed geoelectrical surveys. - Abstract: The physical properties of clay allow argillaceous formations to be considered geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The clays of the Orciatico area (Tuscany, Central Italy), which were thermally altered via the intrusion of an alkali-trachyte laccolith, represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil-gas surveys to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different degrees of thermal alteration. The results of this study show that gas permeability is increased in the clay sequences subjected to greater heat input from the emplacement of the Orciatico intrusion, despite the lack of apparent mineral and geotechnical variations. These results, which take into consideration long time periods in a natural, large-scale geological system, may have important implications for the long-term safety of underground storage of nuclear waste in clay formations.

PIXE analysis on Maya blue in Prehispanic and colonial mural paintings

Energy Technology Data Exchange (ETDEWEB)

Sanchez del Rio, M. [Departamento de Fisica, Universidad Autonoma Metropolitana, Iztapalapa, DF 09340 (Mexico); Martinetto, P. [Laboratoire de Cristallographie, CNRS, BP 166, F-30842 Grenoble (France); Solis, C. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, DF 04510 (Mexico)]. E-mail: corina@fisica.unam.mx; Reyes-Valerio, C. [Instituto Nacional de Antropologi' a e Historia, Mexico, DF (Mexico)

2006-08-15

Particle induced X-ray emission (PIXE) experiments have been carried out at the AGLAE facility (Paris) on several mural samples containing Maya blue from different Prehispanic archaeological sites (Cacaxtla, El Tajin, Tamuin, Santa Cecilia Acatitlan) and from several colonial convents in the Mexican plateau (Jiutepec, Totimehuacan, Tezontepec and Cuauhtinchan). The analysis of the concentration of several elements permitted to extract some information on the technique used for painting the mural, usually fresco. Principal component analysis permitted to classify the samples into groups. This grouping is discussed in relation to geographic and historic data.

Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

Science.gov (United States)

El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

2017-04-01

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite

Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

2010-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were

Euroclay 95. Clays and clay materials sciences. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

Elsen, A; Grobet, P; Keung, M; Leeman, H; Schoonheydt, R; Toufar, H [eds.

1995-08-20

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY `95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately.

Euroclay 95. Clays and clay materials sciences. Book of abstracts

International Nuclear Information System (INIS)

Elsen, A.; Grobet, P.; Keung, M.; Leeman, H.; Schoonheydt, R.; Toufar, H.

1995-01-01

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Science.gov (United States)

Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

2017-06-01

In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Digital Preservation of Ancient Maya Cave Architecture: Recent Field Efforts in Quintana Roo, Mexico

Science.gov (United States)

Rissolo, D.; Lo, E.; Hess, M. R.; Meyer, D. E.; Amador, F. E.

2017-08-01

The presence of ancient Maya shrines in caves serves as unequivocal evidence for the ritual appropriation of these subterranean spaces and their significance with respect to Maya religious practice. Detailed study of the miniature masonry temples and altar features in the caves of Quintana Roo, Mexico reveals a strong stylistic and likely functional correspondence between these structures and their terrestrial counterparts at Postclassic sites. The Proyecto Arquitectura Subterranea de Quintana Roo (coordinated by the Center of Interdisciplinary Science for Art, Architecture, and Archaeology, or CISA3, at the University of California, San Diego and in collaboration with the Instituto Nacional de Antropologia e Historia in Mexico) is conducting a survey and program of digital documentation of both the pristine and impacted cave shrines of the region. Once an area is developed and populated, and access is opened to caves containing ancient architectural features, they are soon vandalized - often resulting in the complete obliteration of these rare miniature buildings and their diagnostic architectural elements. This emergent situation necessitates the use of rapid reality-capture tools; however, the physical challenges of working in caves requires researchers of adapt increasingly common architectural documentation methodologies to more adverse field conditions.

Tratamiento del cuerpo y control social entre los mayas itzaes, siglos XVII-XVIII

Directory of Open Access Journals (Sweden)

Caso Barrera, Laura

2015-12-01

Full Text Available In many societies the human body is considered as a cosmological model and therefore of society. In the case of the Maya Itza we know that the human body is a reference to their territorial, social and religious organization. In this paper we analyze the importance of the human body as a symbolic model, focusing on aspects of Itza religion and rituals, related to the transformation and modification of the human body. We will analyze how Itza society controlled a population with the ability of transfiguration.En diversas sociedades el cuerpo humano se ha concebido como un modelo cosmológico y por lo tanto de la sociedad. En el caso de los mayas itzaes sabemos que el cuerpo humano es un referente para la organización territorial, social y religiosa. En este trabajo se analiza la importancia del cuerpo humano como modelo simbólico, centrándonos en aspectos de la religión y rituales itzaes relacionados con la transformación y modificación del cuerpo humano en el período colonial. Se examina el control que ejerció la sociedad itzá con respecto a una población con la capacidad de transfiguración.

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Directory of Open Access Journals (Sweden)

Landrou Gnanli

2017-01-01

Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Economía y política, factores de cambio en la sociedad clásica maya. Un acercamiento desde la perspectiva de Calakmul

Directory of Open Access Journals (Sweden)

Pablo Alberto Mumary Farto

2011-05-01

Full Text Available A comienzos del siglo XX cuando los estudios mayas no habían hecho nada más que comenzar, se desconocían las cuestiones políticas, económicas y militares que imperaban en la realidad del periodo Clásico. Hoy en día gracias a la arqueología y epigrafía podemos vislumbrar los cambios que se produjeron en la sociedad maya clásica así como la influencia y el papel que jugaron estos factores en su desarrollo

Economía y política, factores de cambio en la sociedad clásica maya. Un acercamiento desde la perspectiva de Calakmul

OpenAIRE

Pablo Alberto Mumary Farto

2011-01-01

A comienzos del siglo XX cuando los estudios mayas no habían hecho nada más que comenzar, se desconocían las cuestiones políticas, económicas y militares que imperaban en la realidad del periodo Clásico. Hoy en día gracias a la arqueología y epigrafía podemos vislumbrar los cambios que se produjeron en la sociedad maya clásica así como la influencia y el papel que jugaron estos factores en su desarrollo

Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications

CSIR Research Space (South Africa)

Musyoka, Nicholas M

2014-10-01

Full Text Available 57 58 59 60 For Peer Review 1 Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications N. M. Musyoka1*, J. Ren1, H. W. Langmi1, D. E. C. Rogers1, B. C. North1, M. Mathe1 and D. Bessarabov2... clear (filtered) extract of cloisite clay, SNC for zeolite from unfiltered cloisite clay extract and SBC for zeolite from unfiltered South African bentonite clay extract. Furfuryl alcohol (Sigma Aldrich, C5H6O2, 98%) and Ethylene gas were used...

Consequences of preferential flow in cracking clay soils for contamination-risk of shallow aquifers

NARCIS (Netherlands)

Oostindie, K.; Bronswijk, J.J.B.

1995-01-01

A method is presented to asses the contamination risk of aquifers covered with cracking clay soils, with special emphasis on preferential flow through shrinkage cracks. A water extraction area was divided into units with homogeneous soil types and hydrological conditions. For each unit, a

Research of Deformation of Clay Soil Mixtures Mixtures

OpenAIRE

Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

2014-01-01

The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

SOBRE LA EDAD DE LOS HORNOS DE CAL EN EL ÁREA MAYA (About the age of the lime kilns in the Maya area

Directory of Open Access Journals (Sweden)

Soledad Ortiz Ruiz

2015-12-01

Full Text Available La investigación que presentamos es sobre el hallazgo y la datación arqueomagnética de hornos de cal en el área maya, México. La relevancia de la datación arqueomagnética consiste en localizar las construcciones arquitectónicas y dilucidar el periodo de utilización por las sociedades que habitaron la zona de ubicación de dichas construcciones. Asumimos que se trataba de hornos prehispánicos por su asociación con el contexto de la excavación. Sin embargo, los resultados de la combinación de dataciones y métodos arqueométricos permitieron ubicar estas estructuras en distintos periodos de utilización y, por tanto, asumir la continuidad de esta tecnología productiva más allá del periodo prehispánico. Asimismo los trabajos de datación nos permiten clarificar la utilización de esta tecnología y práctica productiva en dicha zona cultural. ENGLISH: The investigation presented here is related to the discovery and archaeomagnetic dating of lime kilns in the Maya area, Mexico. The relevance of such dating is to locate architectural constructions and elucidate the period of use by societies that are responsible for their construction. We assume a prehispanic period for the kilns because of their context within the excavation. The combination of dating methods and archaeometric experiments allowed the identification of different periods of use and, therefore, suggests the persistence of this production technology beyond the prehispanic period. Dating work also allows us to clarify the use of this technology and productive practices in this cultural area.

Bilingual Rapping in Yucatán, Mexico: Strategic Choices for Maya Language Legitimation and Revitalisation

Science.gov (United States)

Cru, Josep

2017-01-01

This paper explores the sociolinguistic practices of a group of young bilingual rappers in the Yucatán Peninsula of Mexico. Against the background of ongoing language shift to Spanish in the region, the language choices of a group of Maya youths involved in Hip Hop culture and their agency as policy-makers at the grassroots level is analysed.…

Tiempo histórico y tiempo mítico entre los mayas del Periodo Clásico (ss. II-X d.C.

Directory of Open Access Journals (Sweden)

Lacadena García-Gallo, Alfonso

2004-06-01

Full Text Available The use and development of a rather precise calendrical system enabled the Maya of the Classic Period of this Mesoamerican civilization (centuries 2^nd through 10^th A. D. to turn time into an habitable space. For them, time was like a path leading to either the past, in the form of an historical record registered in written documents, or the future, by way of forecasts and prophecies. Compared to other archaic cultures or early civilizations, the Classic Maya has been known for years for the peculiarity of having a linear, historical concept of time, including absolute dating. Yet the decipherment of the hieroglyphic inscriptions has revealed that this historical concept of time meshed with mythical time to make up a single temporal dimension —which was at once linear and cyclical— for the actions of men as well as gods. With obsessive accuracy and recurrence, the Classic Maya used calendrical Information as mortar for the construction of an historical (especially political and religious discourse on their monuments, full of cross references to contemporary, past and even future events in texts commemorating anniversaries in several calendarial cycles.

La utilización y desarrollo de un sistema calendárico sumamente preciso permitió a los mayas del Periodo Clásico de esta civilización mesoamericana (siglos II-X d.C. hacer del tiempo un espacio habitable. Para ellos, el tiempo era un sendero por el que era posible transitar o bien hacia el pasado, en forma de memoria histórica consignada en textos escritos, o bien hacia el futuro, mediante predicciones y profecías. Lo que es una rareza en comparación con otras culturas arcaicas o primeras civilizaciones, la clásica de los mayas incluía un concepto de tiempo histórico de carácter lineal, con dataciones absolutas. Pero el desciframiento de las inscripciones jeroglíficas está revelando que este tiempo histórico estaba integrado con el mítico en una

Maya phytomedicine in Guatemala - Can cooperative research change ethnopharmacological paradigms?

Science.gov (United States)

Hitziger, Martin; Heinrich, Michael; Edwards, Peter; Pöll, Elfriede; Lopez, Marissa; Krütli, Pius

2016-06-20

This paper presents one of the first large-scale collaborative research projects in ethnopharmacology, to bring together indigenous stakeholders and scientists both in project design and execution. This approach has often been recommended but rarely put into practice. The study was carried out in two key indigenous areas of Guatemala, for which very little ethnopharmacological fieldwork has been published. To document and characterize the ethno-pharmacopoeias of the Kaqchikel (highlands) and Q'eqchi' (lowlands) Maya in a transdisciplinary collaboration with the two groups Councils of Elders. The project is embedded in a larger collaboration with five Councils of Elders representing important indigenous groups in Guatemala, two of which participated in this study. These suggested healing experts reputed for their phytotherapeutic knowledge and skills. Ethnobotanical fieldwork was carried out over 20 months, accompanied by a joint steering process and validation workshops. The field data were complemented by literature research and were aggregated using a modified version of the International Classification of Diseases (ICD-10) and Trotter & Logan's consensus index. Similar numbers of species were collected in the two areas, with a combined total of 530 species. This total does not represent all of the species used for medicinal purposes. Remedies for the digestive system, the central nervous system & behavioral syndromes, and general tissue problems & infections were most frequent in both areas. Furthermore, remedies for the blood, immune & endocrine system are frequent in the Kaqchikel area, and remedies for the reproductive system are frequent in the Q'eqchi' area. Consensus factors are however low. The Kaqchikel, in contrast to the Q'eqchi', report more remedies for non-communicable illnesses. They also rely heavily on introduced species. The transdisciplinary research design facilitated scientifically rigorous and societally relevant large-scale fieldwork, which

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

Energy Technology Data Exchange (ETDEWEB)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

2009-07-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

International Nuclear Information System (INIS)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

2009-01-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

Las organizaciones mayas de Guatemala y el diálogo intercultural

OpenAIRE

Julieta Carla Rostica

2007-01-01

Durante la transición a la democracia en Guatemala surgió un movimiento indígena con reivindicaciones que fueron más allá de la defensa de los derechos humanos individualmente considerados. De cara al genocidio, una de sus demandas más ambiciosas fue la del reconocimiento del derecho maya. El análisis de ésta permitirá caracterizar al movimiento indígena como multiculturalismo emancipatorio, ya que en sí misma es una apuesta al diálogo intercultural e implica no sólo un límite ...

PIXE analysis on Maya blue in Prehispanic and colonial mural paintings

Science.gov (United States)

Sánchez del Río, M.; Martinetto, P.; Solís, C.; Reyes-Valerio, C.

2006-08-01

Particle induced X-ray emission (PIXE) experiments have been carried out at the AGLAE facility (Paris) on several mural samples containing Maya blue from different Prehispanic archaeological sites (Cacaxtla, El Tajín, Tamuin, Santa Cecilia Acatitlán) and from several colonial convents in the Mexican plateau (Jiutepec, Totimehuacán, Tezontepec and Cuauhtinchán). The analysis of the concentration of several elements permitted to extract some information on the technique used for painting the mural, usually fresco. Principal component analysis permitted to classify the samples into groups. This grouping is discussed in relation to geographic and historic data.

Archaeometric study of ceramic figurines from the Maya settlement of La Blanca (Petén, Guatemala)

International Nuclear Information System (INIS)

Horcajada, P.; Roldán, C.; Vidal, C.; Rodenas, I.; Carballo, J.; Murcia, S.; Juanes, D.

2014-01-01

In this article, analytical results will be presented and discussed regarding a selected set of figurines from the ancient Maya settlement of La Blanca in Petén, Guatemala. The objective is to characterize the ceramic material by two analytical complementary techniques: X-ray diffraction (XRD) and total reflection X-ray fluorescence (TXRF). The data obtained by means of both XRD and TXRF were compared and analyzed by multivariate statistical techniques in order to obtain sample groups according to their chemical composition. The results of this archaeometric study have been compared to those that have been obtained through macroscopic characterization by means of the traditional classification system know as Type-Variety. Discordances have been found between the clusters obtained by the Type-Variety classification system and the multivariate classification procedures performed on analytical data. - Highlights: • TXRF and XRD analysis are used in studies of Maya figurines from La Blanca settlement (Guatemala). • Multivariate classification procedures were performed on analytical data to identify figurine groups. • Clustering of analytical data is compared with the traditional Type-Variety classification system

Crystallite size distribution of clay minerals from selected Serbian clay deposits

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Simić Vladimir

2006-01-01

Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

Evidence disputing deforestation as the cause for the collapse of the ancient Maya polity of Copan, Honduras

Science.gov (United States)

McNeil, Cameron L.; Burney, David A.; Burney, Lida Pigott

2009-01-01

Archaeologists have proposed diverse hypotheses to explain the collapse of the southern Maya lowland cities between the 8th and 10th centuries A.D. Although it generally is believed that no single factor was responsible, a commonly accepted cause is environmental degradation as a product of large-scale deforestation. To date, the most compelling scientific evidence used to support this hypothesis comes from the archaeological site of Copan, Honduras, where the analysis of a sediment core suggested a dramatic increase in forest clearance in the Late Classic period (A.D. 600–900). By contrast, in the work presented here, the authors’ analysis of a longer sediment core demonstrates that forest cover increased from A.D. 400 to A.D. 900, with arboreal pollen accounting for 59.8–71.0% of the pollen assemblage by approximately A.D. 780–980. The highest levels of deforestation are found about 900 B.C. when, at its peak, herb pollen made up 89.8% of the assemblage. A second, although less pronounced, period of elevated deforestation peaked at approximately A.D. 400 when herb pollen reached 65.3% of the assemblage. The first deforestation event likely coincided with the widespread adoption of agriculture, a pattern found elsewhere in Mesoamerica. The second period of forest clearance probably was associated with the incursion of Maya speakers into the Copan Valley and their subsequent construction of the earliest levels of the Copan Acropolis. These results refute the former hypothesis that the ancient Maya responded to their increasingly large urban population by exhausting, rather than conserving, natural resources. PMID:20018691

Aspects of clay/concrete interactions

International Nuclear Information System (INIS)

Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

1997-01-01

In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

Physical Properties of Latvian Clays

OpenAIRE

Jurgelāne, I; Stepanova, V; Ločs, J; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

{sup 222}Rn and CO{sub 2} soil-gas geochemical characterization of thermally altered clays at Orciatico (Tuscany, Central Italy)

Energy Technology Data Exchange (ETDEWEB)

Voltattorni, N., E-mail: nunzia.voltattorni@ingv.it [Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome (Italy); Lombardi, S. [Earth Science Department, University ' La Sapienza' , Piazzale A. Moro 5, 00185 Rome (Italy); Rizzo, S. [Via Tito, 1/A, 00061 Anguillara Sabazia, Rome (Italy)

2010-08-15

Research highlights: {yields} Soil-gas technique is applied to study gas permeability of Orciatico clay units. {yields} Clay permeability depends on thermal and mechanical alteration degree. {yields} Soil-gas distributions are due to shallow fracturing of clays. {yields} Rn and CO{sub 2} soil-gas anomalies highlight secondary permeability in clay sequence. {yields} Soil-gas results are supported by detailed geoelectrical surveys. - Abstract: The physical properties of clay allow argillaceous formations to be considered geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The clays of the Orciatico area (Tuscany, Central Italy), which were thermally altered via the intrusion of an alkali-trachyte laccolith, represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil-gas surveys to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different degrees of thermal alteration. The results of this study show that gas permeability is increased in the clay sequences subjected to greater heat input from the emplacement of the Orciatico intrusion, despite the lack of apparent mineral and geotechnical variations. These results, which take into consideration long time periods in a natural, large-scale geological system, may have important implications for the long-term safety of underground storage of nuclear waste in clay formations.

Memorar la cultura: Modos de mantener y formar las identidades mayas modernas Memorialize Culture: Ways to Mantain and Form Modern Mayan Identities

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Felix A. Kupprat

2011-01-01

Full Text Available Memoria ha sido una palabra clave en el proceso de paz en Guatemala durante los últimos quince años. De acuerdo con teorías de la memoria colectiva, ésta forma la identidad de grupos y es sustancial para la construcción y el mantenimiento de la cultura. Al contrastar el movimiento maya con estrategias locales para la conmemoración de las violaciones de los derechos humanos durante el conflicto armado, este artículo conecta el concepto de etnicidad a nivel interregional con la identidad étnica local. Por lo tanto, se propone una división entre los marcadores étnicos sincrónicos y los asincrónicos de la etnicidad maya: el primero se asocia con elementos culturales locales y el segundo con procesos de revitalización. Finalmente, se plantea que los rasgos estructurales, como la memoria cultural, deben ser considerados marcadores étnicos en ambos niveles: el local y el interregional.Memory has been a keyword for the peace process in Guatemala in the last fifteen years. According to theories on collective memory it shapes group identities and is crucial for the construction and maintenance of culture. Contrasting maya cultural activism and local commemorative strategies dealing with human rights violations during the civil war, this paper aims to connect ethnicity on an inter-regional and ethnic identity on a local level. Therefore a division will be made between synchronous and asynchronous ethnic markers of pan-maya identity, associating the former with cultural elements on a local level and the latter with revitalization processes. Finally it is proposed that structural features such as cultural memory should be considered crucial ethnic markers on both levels: the local and the inter-regional.

Evaluation of the bleaching flux in clays containing hematite and different clay minerals

International Nuclear Information System (INIS)

Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos; Morelli, M.R.

2016-01-01

Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

Agrodiversidad y nutrición en Yucatán: una mirada al mundo maya rural

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Javier Becerril

2013-01-01

Full Text Available El uso y aprovechamiento de la agrodiversidad dan continuidad de facto a la conservación de la diversidad genética in situ y a su conocimiento, y generan externalidades positivas en términos de bienestar nutricional. En las áreas rurales de Yucatán, siete de cada diez hombres y mujeres adultos presentan sobrepeso, y veinte de cada cien infantes tienen talla baja, lo que se traduce en un problema dual de salud pública, que aminora el desarrollo rural. En el artículo se analiza la paradoja entre la disponibilidad de diversidad agrícola amplia y el sobrepeso en 390 hogares, en 20 localidades rurales, en las siete regiones de Yucatán. Los hallazgos revelan que las mujeres adultas son las más propensas a la obesidad, pero la condición maya (hablar lengua maya e identificarse como tal, además de mantener usos y costumbres de la cultura sugiere una reducción en el índice de sobrepeso y obesidad, lo que se puede argumentar se debe a los usos y costumbres en el consumo y gestión de la agrodiversidad.

A comparative approach toward understanding the Mycenaean and Late Preclassic lowland Maya early civilisations through their art styles.

NARCIS (Netherlands)

Bajema, Marcus Jan

2015-01-01

My thesis provides a comparative analysis of early cilivilisations through archaeological sources. The two selected cases are Mycenaean Greece and the Late Preclassic lowland Maya. Specifically the study focuses on art and its role in social life of the two cases. Major methodological reflections

Endothelial Nitric Oxide Synthase Haplotypes Are Associated with Preeclampsia in Maya Mestizo Women

Science.gov (United States)

Díaz-Olguín, Lizbeth; Coral-Vázquez, Ramón Mauricio; Canto-Cetina, Thelma; Canizales-Quinteros, Samuel; Ramírez Regalado, Belem; Fernández, Genny; Canto, Patricia

2011-01-01

Preeclampsia is a specific disease of pregnancy and believed to have a genetic component. The aim of this study was to investigate if three polymorphisms in eNOS or their haplotypes are associated with preeclampsia in Maya mestizo women. A case-control study was performed where 127 preeclamptic patients and 263 controls were included. Genotyped and haplotypes for the -768T→C, intron 4 variants, Glu298Asp of eNOS were determined by PCR and real-time PCR allelic discrimination. Logistic regression analysis with adjustment for age and body mass index (BMI) was used to test for associations between genotype and preeclampsia under recessive, codominant and dominant models. Pairwise linkage disequilibrium between single nucleotide polymorphisms was calculated by direct correlation r2, and haplotype analysis was conducted. Women homozygous for the Asp298 allele showed an association of preeclampsia. In addition, analysis of the haplotype frequencies revealed that the -786C-4b-Asp298 haplotype was significantly more frequent in preeclamptic patients than in controls (0.143 vs. 0.041, respectively; OR = 3.01; 95% CI = 1.74–5.23; P = 2.9 × 10−4). Despite the Asp298 genotype in a recessive model associated with the presence of preeclampsia in Maya mestizo women, we believe that in this population the -786C-4b-Asp298 haplotype is a better genetic marker. PMID:21897002

Columns in Clay

Science.gov (United States)

Leenhouts, Robin

2010-01-01

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

75 FR 6249 - Culturally Significant Objects Imported for Exhibition Determinations: “Fiery Pool: The Maya and...

Science.gov (United States)

2010-02-08

... exhibition ``Fiery Pool: The Maya and the Mythic Sea,'' imported from abroad for temporary exhibition within... objects at the Peabody Essex Museum, Salem, MA, from on or about March 27, 2010, until on or about July 18, 2010; the Kimbell Art Museum, Fort Worth, TX, from on or about August 29, 2010, until on or about...

About the Glyph [T544.501] and the Classic Maya Geopolitical Communities

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Rogelio Valencia Rivera

2016-06-01

Full Text Available This paper focuses on the Maya glyph [T544.501]. On one side the article offers a carefully review of the contexts where the hieroglyph appears for, from these, suggest that it may be a logogram with possible OCH ("entrance" reading. Moreover, considering the predominant appearance of this hieroglyph in contexts which relate to geopolitical groups, and beyond its phonetic value, the article also analyzes the historical dynamics that have experienced these Late Classic political groupings as narrate the texts where appears the glyph in question.

DIGITAL PRESERVATION OF ANCIENT MAYA CAVE ARCHITECTURE: RECENT FIELD EFFORTS IN QUINTANA ROO, MEXICO

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D. Rissolo

2017-08-01

Full Text Available The presence of ancient Maya shrines in caves serves as unequivocal evidence for the ritual appropriation of these subterranean spaces and their significance with respect to Maya religious practice. Detailed study of the miniature masonry temples and altar features in the caves of Quintana Roo, Mexico reveals a strong stylistic and likely functional correspondence between these structures and their terrestrial counterparts at Postclassic sites. The Proyecto Arquitectura Subterranea de Quintana Roo (coordinated by the Center of Interdisciplinary Science for Art, Architecture, and Archaeology, or CISA3, at the University of California, San Diego and in collaboration with the Instituto Nacional de Antropologia e Historia in Mexico is conducting a survey and program of digital documentation of both the pristine and impacted cave shrines of the region. Once an area is developed and populated, and access is opened to caves containing ancient architectural features, they are soon vandalized – often resulting in the complete obliteration of these rare miniature buildings and their diagnostic architectural elements. This emergent situation necessitates the use of rapid reality-capture tools; however, the physical challenges of working in caves requires researchers of adapt increasingly common architectural documentation methodologies to more adverse field conditions.

Figurative Language on Maya Angelou selected Poetries

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Risma Hayani

2016-12-01

Full Text Available This study aimed to find out the kinds of figurative language in the five selected poetries of Maya Angelou, the titles are: Alone, Caged Bird, Old Folks Laugh, Phenomenal Woman, Still I Rise. The focus of this study is figurative language which involves: Metaphor, Personification, Hyperbole, Simile, Metonymy, Synecdoche, Irony, Antithesis, Symbolism, and Paradox. Qualitative approach with design of content analysis was used in this study. The researcher acted as the main instrument since she was the one who analyzed the figurative language. Moreover checklist was also used to support her data collection. The data was analyzed through three stages; 1. Data reduction, 2. Data representation, 3. Conclusion. The result of her study showed there were 40 sentences that containing figurative language in five selected poetries of Maya Angelou. They were; Metaphor (13 sentences, Personification (9 sentences, Hyperbole (1 sentence, Simile (8 sentences, Synecdoche (1 sentence, Antithesis (1 sentence, Symbolism (5 sentences, and Paradox (2 sentences. The researcher conclude, if the figurative language used by Angelou to compare, or even symbolize the sentences to bring the meaning come up with beautiful language. Mostly of her poetries told about her experience in the past that rooted to history of the discrimination of American-African.

In situ geochemical properties of clays subject to thermal loading

International Nuclear Information System (INIS)

Chapman, N.A.

1980-01-01

Compositional variation and geochemical environment in an argillaceous unit are a function of age, depth of burial and mode of origin. This paper considers the variation limits likely to be encountered in potential repository host rocks and examines the significance of factors such as porosity, pore-fluid pressure, total fluid content, and major and accessory mineral component behaviors in controlling the geochemical environment in the neighbourhood of a thermally active waste canister. Particular attention is paid to the use of Eh-pH diagrams in assessing corrosion environments and nuclide speciation. The paper outlines the variables which must be considered when endeavouring to interpret such plots (e.g. temperature, concentration, concurrent reactions and probabilities) and uses the behavior of various iron minerals found in clay deposits under specific conditions to illustrate the complexities. The overall thermal stability of various clay and accessory minerals is discussed and extended to attempt to predict behavior under deep repository conditions, using available data on the diagenetic characteristics of clay-rich sediments. The physical behavior of fluids in plastic clays is considered and methods evaluated for deriving induced geochemical conditions in a thermally active repository. The latter section is particularly related to canister corrosion studies, in situ experiments, and waste dissolution parameters

Effects of Different Types of Clays and Maleic Anhydride Modified Polystyrene on Polystyrene/Clay Nanocomposites

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M. Mehrabzadeh

2013-01-01

Full Text Available Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt% can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM and X-ray diffraction (XRD techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30% and elongation-at-break (~40% of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

Thixotropic Properties of Latvian Illite Containing Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

2015-01-01

Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

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Simona eLongo

2013-11-01

Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

La conservación del patrimonio arquitectónico maya. Primeras experiencias (1891-1969)

OpenAIRE

MATARREDONA DESANTES, NURIA

2016-01-01

[EN] The Mayan civilization is, undoubtedly, the most advanced of those that flourished in America during pre-Columbian times. During its heyday period, the ancient Maya built large cities and created large residential areas where they erected an impressive architecture in harmony with the ferocious nature that surrounded them. Today, the testimony of these settlements comes immersed in a wild environment, buried under abundant vegetation and even the collapse of the same architectural struct...

The Movement, the Mine and the Lake: New Forms of Maya Activism in Neoliberal Guatemala

Directory of Open Access Journals (Sweden)

J. T. Way

2016-07-01

Full Text Available This article explores the social, economic, cultural and political issues bound up in two matters relating to the environment in the Sololá and Lake Atitlán region of the Guatemalan Mayan highlands in 2004–2005: the violent breakup of an anti-mine protest and the various reactions to a tropical storm that threatened the lake ecosystem. It views these events as part of a historical conjuncture and centers them in a larger discussion of Maya political activism, environmentalism and neoliberal development in Guatemala from the 1990s–mid-2010s. It begins with the transition from war to peace in the 1990s, charting how Maya participation in municipal politics soared even as the official Mayan movement waned as the state turned to neoliberalism. Zooming in on municipal development and politics in Sololá in the early 2000s, it then traces at the ground level how a decentralizing, “multicultural” state promoted political participation while at the same time undermining the possibility for that participation to bring about substantive change. The center of the article delves deeper into the conjuncture of the first decade of the new millennium. By mapping events in Sololá against development, agrarian transformation and rural urbanization, it argues that resilient Maya community structures, although unable to stop the exploitative tide, continued to provide local cohesion and advocacy. Activists and everyday citizens became more globally attuned in the 2000s. The article’s final section analyzes municipal plans made between 2007 and 2012, arguing that creating and controlling community structures became increasingly important to the state in a time when Guatemala’s “outward” global turn was accompanied by an “inward” turn as people confronted spiraling violence in their communities. Critics called young people apolitical, but in 2015, massive demonstrations led to the imprisonment of the nation’s president and vice

Inferring Ancient Technology and Practices of the Elite Maya Kingship Through the Application of Materials Engineering Characterization Modalities

Science.gov (United States)

Cheung, Kristina Alyssa

This project focuses on the characterization of materials from burial offerings and painted decoration in a royal Maya tomb at El Zotz, Guatemala, and their association with mortuary rituals. Archaeological findings included vessels, jade masks, organic materials (wood, cord, and textiles), specular hematite cubes, shells with powdered cinnabar, green (malachite) painted stucco assumed to have decorated the wooden bier where the king was resting, and caches of lip-to-lip Aguila Orange bowls containing human phalanges. This paper describes findings from non-invasive and non-destructive analytical techniques including XRF, VPSEM-EDS, and XRD, emphasizing the potential of these combined technologies in the identification of organic and inorganic markers to infer burial customs. The nature and location of the findings, the evidence of pigment coloration on the bones employing hematite and cinnabar, and the indication of exposure of the bones to high temperatures suggest highly complex, even protracted mortuary practices of Maya elite.

What makes a natural clay antibacterial?

Science.gov (United States)

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

Viscosity and Plasticity of Latvian Illite Clays

OpenAIRE

Jurgelāne, I; Vecstaudža, J; Stepanova, V; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

Clay Portrait Boxes

Science.gov (United States)

Wilbert, Nancy Corrigan

2009-01-01

In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

Clay matrix voltammetry

International Nuclear Information System (INIS)

Perdicakis, Michel

2012-01-01

Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

Energy Technology Data Exchange (ETDEWEB)

Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

2010-08-31

As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

International Nuclear Information System (INIS)

Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

2010-01-01

As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

Clay Animals and Their Habitats

Science.gov (United States)

Adamson, Kay

2010-01-01

Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

Science.gov (United States)

Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

2002-07-01

In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

21 CFR 186.1256 - Clay (kaolin).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain...

The influence of clay minerals on acoustic properties of sandstones

Energy Technology Data Exchange (ETDEWEB)

Hansen, Olav

1997-12-31

This thesis aims to provide better understanding of the relationship between the acoustic properties and the petrophysical/mineralogical properties in sand-prone rock. It emphasizes the influence of clay minerals. The author develops a method to deposit clay minerals/mineral aggregates in pore space of a rigid rock framework. Kaolinite aggregates were flushed into porous permeable Bentheimer sandstone to evaluate the effect of pore filling minerals on porosity, permeability and acoustic properties. The compressional velocity was hardly affected by the clay content and it was found that the effect of minor quantities of pore filling minerals may be acoustically modelled as an ideal suspension, where the pore fluid bulk modulus is modified by the bulk modulus of the clay minerals. The influence of clays on acoustic velocities in petroleum reservoir rocks was investigated through ultrasonic measurements of compressional- and shear-waves on core material from reservoir and non-reservoir units on the Norwegian Continental Shelf. The measured velocities decrease as the porosity increases, but are not strongly dependent on the clay content. The measured velocities are less dependent on the petrophysical and lithological properties than indicated by previous authors and published mathematical models, and stiffness reduction factors are introduced in two of the models to better match the data. Velocities are estimated along the wellbores based on non-sonic well logs and reflect well the actual sonic log well measurements. In some wells the compressional velocity cannot be modelled correctly by the models suggested. Very high compressional wave anisotropy was measured in the dry samples at atmospheric conditions. As the samples were saturated, the anisotropy was reduced to a maximum of about 30% and decreases further upon pressurization. Reservoir rocks retrieved from 2500 m are more stress dependent than those retrieved from less than 200 m depth. 168 refs., 117 figs., 24

Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

DEFF Research Database (Denmark)

Sørensen, Morten Kanne; Fabricius, Ida Lykke

2013-01-01

Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...... sandstones....

Clay shale as host rock. A geomechanical contribution about Opalinus clay; Tonstein als Wirtsgestein. Ein geomechanischer Beitrag ueber Opalinuston

Energy Technology Data Exchange (ETDEWEB)

Lempp, Christof; Menezes, Flora; Sachwitz, Simon [Halle-Wittenberg Univ., Halle (Saale) (Germany). Inst. fuer Geowissenschaften und Geographie

2016-12-15

The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

Quality indicators and shelf life of red octopus (Octopus maya) in chilling storage

OpenAIRE

GULLIAN-KLANIAN,Mariel; SÁNCHEZ-SOLÍS,María José; TERRATS-PRECIAT,Montserrat; DELGADILLO-DÍAZ,Mariana; ARANDA,Javier

2016-01-01

Abstract There are no precedents concerning the quality of Octopus maya during chilled storage. This study evaluated the shelf life of the red octopus in chilling storage (4oC) and the correlation of the sensory quality index with microbiological counting and the biochemical indicators (hypoxanthine, histamine and volatile amines). A total of 112 whole raw octopi (average weight of 896 g) were randomly selected from seven batches and exposed to 4°C for 18, 24, 48, 72, 84, 96, and 100 h. The h...

Mineral acquisition from clay by budongo forest chimpanzees

NARCIS (Netherlands)

Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay

Leachability of fired clay brick incorporating with sewage sludge waste

Science.gov (United States)

Kadir, Aeslina Abdul; Salim, Nurul Salhana Abdul; Sarani, Noor Amira; Rahmat, Nur Aqma Izurin; Abdullah, Mohd Mustafa Al Bakri

2017-09-01

Sewage sludge is sewerage from wastewater treatment plants that generates millions tons of sludge ever year. Regarding this activity, it causes lack management of waste which is harmful to the surrounding conditions. Therefore, this study is focuses on the incorporation of sewage sludge waste into fired clay brick to provide an option of disposal method, producing adequate quality of brick as well as limiting the heavy metal leachability to the environment. Sewage sludge brick (SSB) mixtures were incorporated with 0%, 1%, 5%, 10%, 20% and 30% of sewage sludge waste (SSW). Heavy metals of crushed SSB were determined by using Toxicity Characteristic Leaching Procedure (TCLP) according to Method 1311 of United State Environment Protection Agency (USEPA) standard. From the results obtained, up to 20% of SSW could be incorporated into fired clay brick and comply with the USEPA standard. Therefore, this study revealed that by incorporating SSW into fired clay brick it could be an alternative method to dispose the SSW and also could act as a replacement material for brick manufacturing with appropriate mix and design.

Evaluation of kaolinite clays of Moa for the production of cement based clinker-calcined clay-limestone (LC3

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Roger S. Almenares-Reyes

2016-12-01

Full Text Available Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (ATG. These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1, although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C.

Near-surface Imaging of a Maya Plaza Complex using Ground-Penetrating Radar

Science.gov (United States)

Aitken, J. A.; Stewart, R. R.

2005-05-01

The University of Calgary has conducted a number of ground-penetrating radar surveys at a Maya archaeological site. The purpose of the study is to discern the near-surface structure and stratigraphy of the plaza, and to assist the archaeologists in focusing their excavation efforts. The area of study is located in Belize, Central America at the ancient Maya site of Maax Na. Flanked by structures believed to be temples to the north and west, the archaeologists were interested in determining how many levels of plaza were built and if there was any discernable slope to the plaza. Over the last three years, both 2-D lines and 3-D grids were acquired at the plaza using a Sensors and Software Inc. Noggin Plus system at an antenna frequency of 250 MHz. The processing flow consisted of the application of gain, various filtering techniques and a diffraction stack migration using Reflexw. Interpolation of the gridded data was investigated using simple averaging, F-K migration, pre-stack migration and inversion techniques. As this study has evolved over different field seasons, measured velocities appear to change with the saturation level of the shallow section. Velocity measurements ranged from 0.058 - .106 m/ns during the wet conditions encountered in 2002 and 2004, while velocities of 1.22 - 1.40 m/ns were measured in the drought of 2003. The GPR images to date indicate continuous and interpretable images of the subsurface, showing evidence of structure, discontinuities and amplitude variations. A number of interesting anomalies have been identified, and prioritized for excavation.

Influence of herbicide structure, clay acidity, and humic acid coating on acetanilide herbicide adsorption on homoionic clays.

Science.gov (United States)

Liu, Weiping; Gan, Jianying; Yates, Scott R

2002-07-03

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.

Alpha particles emitted from the surface of granite, clay, and its fired products, 1

International Nuclear Information System (INIS)

Aratani, Michi; Otsuka, Hideko

1975-01-01

As a part of an investigation on ''the effect of long-time irradiation from a trace amount of radioisotopes'', the emitting rate of alpha particles per unit surface area (apparent) coming from natural alpha-particle emitters has been measured. The samples measured were granite and its weathered product; clay, especially potter's clay, and its fired product; pottery ware. The values obtained were 39.1 +-0.9--0.73+-0.08 cpm/100 cm 2 in granite, 16.8+-0.4--6.4+-0.2 cpm/100cm 2 in potter's clay, and 1.36+-0.04--0.82+-0.04 cpm/100cm 2 in pottery ware on substrate, and 1.33+-0.05--0.32+-0.02 cpm/100cm 2 on glazer. (auth.)

Mineralogy and geotechnical characteristics of some pottery clay

Directory of Open Access Journals (Sweden)

Mujib Olamide ADEAGBO

2016-12-01

Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

Xenon-129 NMR study of the microporous structure of clays and pillared clays

International Nuclear Information System (INIS)

Tsiao, C.; Carrado, K.A.

1990-01-01

129 Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diameter of montmorillonite increases, for example, from 5.4 Angstrom to 8.0 Angstrom after pillaring cheto-montmorillonite with aluminum polyoxohydroxy Keggin cations. The data are consistent with X-ray powder diffraction results, which show a corresponding increase in the interlamellar gallery height from 5.6 Angstrom to 8.4 Angstrom

Study of reactions induced by the halo nucleus 11Li with the active target MAYA

International Nuclear Information System (INIS)

Roger, Th.

2009-09-01

Active targets are perfect tools for the study of nuclear reactions induced by very low intensity radioactive ion beams. They also enable the simultaneous study of direct and compound nuclear reactions. The active target MAYA, built at GANIL, has been used to study the reactions induced by a 4.3*A MeV 11 Li beam at the ISAC2 accelerator TRIUMF (Canada). The angular distributions for the elastic scattering and the one and two neutron transfer reaction have been reconstructed. The elastic scattering angular distribution indicates a strong enhancement of the flux absorption with respect to the neighbouring nuclei. From a coupled channel analysis of the two neutron transfer reaction for different three body models, the information on the structure of the halo of the Borromean nucleus 11 Li have been extracted. Meanwhile, the energy dependence of the elastic scattering reaction has been studied, using the active target MAYA as a thick target. The resulting spectrum shows a resonance around 3 MeV centre of mass. This resonance could be an isobaric analog state of 12 Li, observed in 12 Be. R matrix calculations have been performed in order to extract the parameters (spin and parity) of this state. (author)

EL CUERPO Y LA PERSONA EN EL ESPACIO-TIEMPO DE LOS MAYAS DE LOS CHENES, CAMPECHE

Directory of Open Access Journals (Sweden)

Javier Hirose López

2007-12-01

Full Text Available Para los médicos tradicionales mayas de la región de los Chenes, en el estado de Campeche, winik, el término que designa a la persona, hombre o individuo (Barrera Vázquez 2001, está estrechamente ligado al simbolismo de los rituales de sanación y los principios de la cosmovisión maya. En contraste con la visión cartesiana del mundo, propia de la mente occidental, que separa el cuerpo de la mente y el espíritu, para los mayas la persona se manifiesta en su forma material, el cuerpo, kukut, como reflejo del cosmos, con cuatro rumbos y un centro, y se conforma por los elementos de la naturaleza: tierra, agua, fuego, viento y luz. Simultáneamente, los mismos componentes que conforman su materialidad se manifiestan como entidades sutiles a través de las cuales el individuo se interrelaciona con los diferentes niveles del cosmos. Dicha interacción se da en un espacio delimitado por cuatro lados, cuyo movimiento —en contrasentido al giro de las manecillas del reloj— lo liga con el tiempo.   ABSTRACT For the mayan traditional healers of the Chenes region in Campeche, winik, the term used to designate a “person”, “man” or “individual”(Barrera-Vázquez 2001, is closely linked to the healing rituals and the principles of mayan cosmology. The Cartesian world view, proper to the occidental mind, separates the body from the mind and the spirit. In contrast, for the mayan, the person has a material aspect, the body, kukut, which resembles the cosmos, with four orientations and a center, and is the manifestation of the elements present in nature: earth, water, fire, wind and light. Simultaneously, the same components that conform its materiality, are manifest as subtle entities that let the individual interact with the different levels of the cosmos. This interaction takes place in a dimension defined by a four sided space which moves in the universe in a counter-clockwise direction.

Wave liquefaction in soils with clay content

DEFF Research Database (Denmark)

Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

2012-01-01

The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

Characterization of clay minerals

International Nuclear Information System (INIS)

Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

2002-01-01

The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

Description of Arundel Clay ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an “Ostrich Dinosaur”: biogeographic implications

Directory of Open Access Journals (Sweden)

Chase Doran Brownstein

2017-03-01

Full Text Available The fossil record of dinosaurs from the Early Cretaceous of Eastern North America is scant, especially since a few stratigraphic units from the east are fossiliferous. Among these stratigraphic units, the Arundel Clay of the eastern seaboard has produced the best-characterized dinosaur faunas known from the Early Cretaceous of Eastern North America. The diverse dinosaur fauna of the Arundel Clay has been thoroughly discussed previously, but a few of the dinosaur species originally described from the Arundel Clay are still regarded as valid genera. Much of the Arundel material is in need of review and redescription. Among the fossils of dinosaurs from this stratigraphic unit are those referred to ornithomimosaurs. Here, the researcher describes ornithomimosaur remains from the Arundel Clay of Prince George’s County, Maryland which may be from two distinct ornithomimosaur taxa. These remains provide key information on the theropods of the Early Cretaceous of Eastern North America. Recent discoveries of small theropod material from the Arundel Clay possibly belonging to ornithomimosaurs are also reviewed and described for the first time. The description of the Arundel material herein along with recent discoveries of basal ornithomimosaurs in the past 15 years has allowed for comparisons with the coelurosaur Nedcolbertia justinhofmanni, suggesting the latter animal was a basal ornithomimosaur rather than a “generalized” coelurosaur as it was originally described. Comparisons between the Arundel ornithomimosaur material and similar Asian and European specimens suggest that both extremely basal ornithomimosaurs and more intermediate or derived forms may have coexisted throughout the northern hemisphere during the Early Cretaceous.

Dietetic determinants of zinc consumption in stunted children under five in maya communities from Guatemala

OpenAIRE

Monroy-Valle, Michele; Universidad Rafael Landívar, Facultad de Ciencias de la Salud, Licenciatura en Nutrición Universidad de San Carlos de Guatemala, Facultad de Ciencias Químicas y Farmacia, Unidad de Estadística, Epidemiología y Salud Pública; Coyoy, Wendy; Universidad Rafael Landívar, Facultad de Ciencias de la Salud, Licenciatura en Nutrición; De León, Jorge; Universidad de San Carlos de Guatemala, Facultad de Ciencias Químicas y Farmacia, Unidad de Estadística, Epidemiología y Salud Pública; Flórez, Iván D.; Departamento de Pediatría y Puericultura, Universidad de Antioquia, Medellín, Colombia; Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Canada.

2017-01-01

The objective of the study was to identify the elements from feeding patterns that influence the intake and bioavailability of zinc in stunted children (SC) 1-5 years from Maya communities living in Huehuetenango, Guatemala. This descriptive, cross-sectional study was performed in 138 stunted children aged 1-5 years. It was applied: an inventory of zinc food sources availability, a Food Frequency Questionnaire, a questionnaire about living conditions. anthropometrics measurements and informat...

Clays and Clay Minerals and their environmental application in Food Technology

Science.gov (United States)

del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

2013-04-01

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Directory of Open Access Journals (Sweden)

Vernon Reynolds

Full Text Available Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Science.gov (United States)

Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Influence of carbonate micro-fabrics on the failure strength of Callovo-Oxfordian clay stones and Opalinus Clay

International Nuclear Information System (INIS)

Klinkenberg, M.; Dohrmann, R.; Kaufhold, S.; Siegesmund, S.

2010-01-01

Document available in extended abstract form only. The potential use of clay stones as host rock for radioactive waste disposal is currently investigated. For this application, hydraulic conductivity, swelling properties, water uptake, rheological and mechanical properties are of great importance. The Opalinus Clay (Mont-Terri, Switzerland) and the Callovo- Oxfordian clay stone (France) are the most frequently studied clay stones. One goal is to develop a numerical model being able to predict the mechanical behaviour of clay stones under repository-like conditions. Experimental investigations reveal that Opalinus Clay and Callovo-Oxfordian clay stone behave different with respect to the dependence of mechanical strength on the carbonate content. The failure strength of Opalinus Clay decreases with increasing carbonate content, whereas it increases with increasing carbonate content when Callovo-Oxfordian clay stone is considered. To supply proper data and enable reliable model assumptions, the use of suitable experimental techniques for the description of the microstructure is indispensable. After mechanical testing, samples were taken perpendicular to the bedding and polished sections were prepared. The micro-fabrics were investigated using scanning electron microscopy (SEM) and image analysis. Backscattered electron (BSE) images were used for the image analysis because carbonates can be extracted by grey level analysis. The image analysis of the extracted particles provides the following parameters: area, longest and shortest axis of an ellipse (surrounding the particle), perimeter, the angle to horizontal (longest axis), and the aspect ratio (longest axis/shortest axis). Callovo-Oxfordian clay stone shows a homogenous distribution of fine-grained carbonates and dovetail connection of calcium carbonate with the clayey matrix. In contrast Opalinus Clay shows large elongated carbonate grains (high aspect ratios) of shell fragments. Cracks are mostly related to these

Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

International Nuclear Information System (INIS)

Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

2009-01-01

Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

Two new species of dicyemid mesozoans (Dicyemida: Dicyemidae) from Octopus maya Voss & Solis-Ramirez (Octopodidae) off Yucatan, Mexico.

Science.gov (United States)

Castellanos-Martinez, Sheila; Aguirre-Macedo, M Leopoldina; Furuya, Hidetaka

2016-07-01

Two new dicyemid species are described from the endemic cephalopod Octopus maya Voss & Solis-Ramirez collected off Yucatan, Mexico. The renal sacs of 40 juvenile and adult octopuses from four localities were examined. Dicyema hochbergi n. sp. is a medium-sized species that reaches 2,245 µm in length. The vermiform stages consist of 18-24 peripheral cells, a conical calotte and the extension of the axial cell between the base and middle of the metapolar cells. Infusoriform embryos consist of 39 cells with urn cell containing one germinal cell, two nuclei and solid refringent bodies. Dicyema mexcayae n. sp. is a relatively small species that reaches 1,114 µm in length. The vermiform stages are constituted by 14-16 peripheral cells, an elongate calotte and the axial cell extending forward to the middle of the metapolar cells. The infusoriform embryos consist of 37 cells, two solid refringent bodies and urn cells with two nuclei each. The present study represents the first description of a dicyemid species from O. maya and increases the number of described species from Mexican waters to 11.

Crude oil polycyclic aromatic hydrocarbons removal via clay-microbe-oil interactions: Effect of acid activated clay minerals.

Science.gov (United States)

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-07-01

Acid treatment of clay minerals is known to modify their properties such as increase their surface area and surface acidity, making them suitable as catalysts in many chemical processes. However, the role of these surface properties during biodegradation processes of polycyclic aromatic hydrocarbons (PAHs) is only known for mild acid (0.5 M Hydrochloric acid) treated clays. Four different clay minerals were used for this study: a montmorillonite, a saponite, a palygorskite and a kaolinite. They were treated with 3 M hydrochloric acid to produce acid activated clay minerals. The role of the acid activated montmorillonite, saponite, palygorskite and kaolinite in comparison with the unmodified clay minerals in the removal of PAHs during biodegradation was investigated in microcosm experiments. The microcosm experiments contained micro-organisms, oil, and clays in aqueous medium with a hydrocarbon degrading microorganism community predominantly composed of Alcanivorax spp. Obtained results indicated that acid activated clays and unmodified kaolinite did not enhance the biodegradation of the PAHs whereas unmodified montmorillonite, palygorskite and saponite enhanced their biodegradation. In addition, unmodified palygorskite adsorbed the PAHs significantly due to its unique channel structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

From clay bricks to deep underground storage

International Nuclear Information System (INIS)

2012-05-01

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the use of clay strata for the storage of radioactive wastes in deep-lying repositories. First of all, a geological foray is made concerning the history of the use of clay and its multifarious uses. The characteristics of clay and its composition are examined and its formation in the geological past is explained. In particular Opalinus clay is looked at and the structures to be found are discussed. The clay's various properties and industrial uses are examined and its sealing properties are examined. Also, Bentonite clay is mentioned and work done by Nagra and co-researchers is noted

Microstructure and Thermal Properties of Polypropylene/Clay Nanocomposites with TiCl4/MgCl2/Clay Compound Catalyst

Directory of Open Access Journals (Sweden)

Limei Wang

2015-01-01

Full Text Available Polypropylene (PP/clay nanocomposites were synthesized by in situ intercalative polymerization with TiCl4/MgCl2/clay compound catalyst. Microstructure and thermal properties of PP/clay nanocomposites were studied in detail. Fourier transform infrared (FTIR spectra indicated that PP/clay nanocomposites were successfully prepared. Both wide-angle X-ray diffraction (XRD and transmission electron microscopy (TEM examination proved that clay layers are homogeneously distributed in PP matrix. XRD patterns also showed that the α phase was the dominate crystal phase of PP in the nanocomposites. Thermogravimetric analysis (TGA examinations confirmed that thermal stability of PP/clay nanocomposites was markedly superior to pure PP. Differential scanning calorimetry (DSC scans showed that the melt temperature and the crystallinity of nanocomposites were slightly lower than those of pure PP due to crystals imperfections.

Fire performance of fiber board coated with nano kaolin-clay film

Science.gov (United States)

Zhijia Liu; John F. Hunt; Zhiyong Cai

2013-01-01

Fiberboard is a common interior material used both in China and the United States of America. The increase in demand for interior materials has raised concerns regarding combustibility of the materials. The pyrolysis characteristics of fiber, phenolic resin (PF), and nano kaolin-clay (NK) were investigated using thermogravimetry. The fire performances of samples coated...

Use of Bentonite Clay for the Reduction of Cyanide Poisoning after ...

African Journals Online (AJOL)

ADOWIE PERE

ABSTRACT: The in vivo study of the effect of bentonite on cyanide poisoning and its effect on plasma urea was ... clumping action of clay makes it bind to heavy metals and pathogens to ... They are rare but potentially ..... action of plant enzymes and subsequent leaching. .... Fuller's earth resources of the United States. U.S..

Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

Energy Technology Data Exchange (ETDEWEB)

Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2012-07-01

Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

Feasibility of using overburden clays for sealing purposes and laboratory testing of the clays

Energy Technology Data Exchange (ETDEWEB)

Mann, J. (Vyzkumny Ustav pro Hnede Uhli, Most (Czechoslovakia))

1992-03-01

Studies properties of overburden clay from North Bohemian surface coal mines for use as sealants of industrial and household waste that will be dumped at Czechoslovak surface mine sites. Basic requirements of sealing layers are optimum compressibility and impermeability by suitable compacting. Laboratory soil mechanical tests of different clay samples were carried out using the Proctor standard tests (PCS) and the Norwegian Geonor A/S - m 45 instrument. Laboratory tests were used to select the best available clay types with optimum density and moisture content. Experimental results of laboratory tests are provided.

Sorption of radionuclides by tertiary clays

International Nuclear Information System (INIS)

Wagner, J.F.; Czurda, K.A.

1990-01-01

The sorption capacity of different clay types for some metals (Co, Cs, Sr and Zn), occurring as common radionuclides in radioactive waste deposits, had been analysed by a static (batch technique) and a dynamic method (percolation tests, in which the driving force is a hydraulic gradient). Sorption capacity generally increased with an increasing pH of solution. A decrease of sorption capacity had been observed in the order Zn > Cs ≥ Co > Sr for the batch and Cs > Zn > Sr > Co for the percolation tests. Clay marls showed a distinctly higher sorption respectively retention capacity as pure clays. Sorption capacity depends on solution parameters like type and concentration of radionuclide, pH, salt concentration, etc., and on rock parameters like mineral content (e.g. swelling clay minerals and carbonates), organic material, rock pH, micro fabric, etc. A third parameter of great influence is the contact time between clay and solution. The adsorption isotherms reflect two different adsorption mechanisms: a very rapid adsorption (a few minutes) on the external surfaces of clay minerals and a slow adsorption process (weeks and longer), due to the diffusion of metal ions into the interlayer space of clay minerals. 12 refs., 9 figs., 1 tab

Characterization of archaeological ceramics from the north western lowland Maya Area, using the technique of neutron activation analysis; Caracterizacion de ceramicas arqueologicas de las tierras bajas noroccidentales del Area Maya, empleando la tecnica de activacion neutronica

Energy Technology Data Exchange (ETDEWEB)

Lopez R, M. C.; Tenorio, D.; Jimenez R, M. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Terreros, E. [Museo del Templo Mayor, INAH, Seminario No. 8, Col. Centro, Mexico 06060, D. F. (Mexico); Ochoa, L. [UNAM, Instituto de Investigaciones Antropologicas, Circuito Exterior s/n, Ciudad Universitaria, Mexico 04510, D. F. (Mexico)

2008-07-01

It is a study on 50 samples of ceramics from various archaeological sites of the north western lowland Maya Area. This study was performed by neutron activation analysis of 19 chemical elements and the treatments relevant statistical data. Significant differences were found among the pieces that led to group them into five major groups, the difference is the site of their manufacture and therefore in the raw materials used for this. (Author)

Organophilization and characterization of commercial bentonite clays

International Nuclear Information System (INIS)

Cunha, B.B. da; Lima, J.C.C.; Alves, A.M.; Araujo, E.M.; Melo, T.J.A. de

2012-01-01

Bentonite clay is a plastic changes resulting from volcanic ash, consisting mostly of montmorillonite. The state of Paraiba is a major source of bentonite clay from Brazil, where the main oil fields are located in Boa Vista and represents the largest national production of raw and beneficiated bentonite. Aimed at the commercial value of this type of clay and its high applicability in the polls, this article aims to make a comparison between two kinds of clay, a national (Brasgel) and other imported (Cloisite) from organophilization of two commercial bentonite, ionic surfactant with Praepagem WB, and characterize them by XRD, FTIR and TG / DTG. We observe that despite getting inferior properties, the clay presents national values very similar to those presented by imported clay. (author)

Regional response to drought during the formation and decline of Preclassic Maya societies

Science.gov (United States)

Ebert, Claire E.; Peniche May, Nancy; Culleton, Brendan J.; Awe, Jaime J.; Kennett, Douglas J.

2017-10-01

The earliest complex societies and a distinctive set of pan-regional social, political, and economic institutions appeared in the southern Maya lowlands during the Preclassic period (ca. 1200/1100 cal BCE-cal 300 CE). The timing of these cultural changes was variably influenced by local developments, interaction with other regions of Mesoamerica, and climate change. We present a high-resolution radiocarbon chronology for the growth of the early polity of Cahal Pech, Belize, one of the first permanent settlements in the southern Maya lowlands. We compare our results to a database containing over 1190 radiocarbon dates from cultural contexts reported from five major regions of the southern lowlands to interpret the expansion and decline of emerging complex social groups during the Preclassic. Comparisons to paleoclimate proxy datasets suggest that fluctuating climate regimes may have promoted alternating integration and fragmentation of early hierarchically organized societies. Stable climatic conditions during the Middle Preclassic (1000/900-300 cal BCE) fostered the centralization of populations and the formation of large regional polities across the southern lowlands. An extended drought at the end of the Late Preclassic (cal 150-300 CE) likely contributed to the decline of some major polities in the central Petén, but smaller sites located in productive environments were more resilient and persisted in to the Classic period. This research provides a framework for understanding the complex social and environmental factors that influenced localized adaptations to climate change and the episodic growth and decline of early complex societies in prehistory.

Thermal Behaviour of clay formations

International Nuclear Information System (INIS)

Tassoni, E.

1985-01-01

The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm -1 . 0 C -1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

Silt-clay aggregates on Mars

International Nuclear Information System (INIS)

Greeley, R.

1979-01-01

Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition, and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles. Electrification is proposed to occur within Martian dust clouds, generating silt-clay aggregates which would settle to the surface where they may be deposited in the form of sandlike structures. By analog, silt-clay dunes are known in many parts of the earth where silt-clay aggregated were transported by saltation and deposited as 'sand.' In these structures the binding forces were later destroyed, and the particles reassumed the physical properties of silt and clay, but the sandlike bedding structure within the 'dunes' was preserved. The bedding observed in drifts at the Viking landing site is suggested to result from a similar process involving silt-clay aggregates on Mars

El modelado artificial de la cabeza durante la Colonia: Una tradición maya en el espejo de las fuentes históricas Artificial Head Modification during the Colonial Era: A Mayan Tradition in the Mirror of Historical Sources

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Vera Tiesler

2011-01-01

Full Text Available Este trabajo aporta una mirada alterna sobre la modificación cefálica artificial entre los mayas, concretamente utilizando las observaciones de los cronistas que aún la vieron en la época Colonial. Sin querer, ellas nos comunican motivaciones íntimamente vinculadas con el rol que una vez tuvo la costumbre cefálica dentro de la cosmovisión y la ritualidad cotidiana de los mayas prehispánicos; así, estos testimonios constituyen puntos de partida invaluables para comprender los motivos culturales profundos que el modelado cefálico satisfacía originalmente. Por último, contrastamos y discutimos la información de las fuentes conjuntamente con el registro craneológico en siete series coloniales del territorio cultural maya. Los resultados confirman que el modelado cefálico pronto pierde vigencia en los centros urbanos con mayor presencia europea al mismo tiempo que se observa su pervivencia en los espacios rurales y selváticos más aislados, como los paraderos remotos de la selva lacandona.This paper contributes an alternative view on artificial head shaping practices among the Maya, which we examine through the lens of those European chroniclers who still witnessed it as a living practice during the colonial era. Unwillingly, these sources testify longstanding cultural motivations for the ancient tradition of modifying infants' vaults, which appear intimately tied to prehispanic Maya worldviews and daily ritual practices. The recognition of these motives provides a valuable point of departure for understanding the deeply embedded cultural roles this head practice once played. The last part of the paper compares and discusses the information provided by the colonial sources jointly with the results obtained from a study of seven colonial skeletal series from the Maya area. Our results confirm that Maya head modeling quickly dwindled within the urban spheres, where the European dominion was most immediate, while surviving over the

What Makes a Natural Clay Antibacterial?

Science.gov (United States)

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

Maya Lime Mortars—Relationship between Archaeomagnetic Dating, Manufacturing Technique, and Architectural Function—The Dzibanché Case

Directory of Open Access Journals (Sweden)

Luisa Straulino Mainou

2016-11-01

Full Text Available Researchers have related the manufacturing technique of plasters and stucco in the Maya area with their period of production but not with their architectural function. In this paper, we establish a relationship between those three features (manufacturing technique, age, and architectural function in the plasters of the Maya site of Dzibanché in southern Quintana Roo. Dzibanché has abundant remains of stuccos and plasters found mainly in three buildings (Plaza Pom, Pequeña Acrópolis, and Structure 2. We used thin sections, SEM and XRD, and archaeomagnetic dating processes. The pictorial layer of Structure 2 was the earliest (AD 274–316 and the stuccoes and plasters of the other two buildings were dated to the Middle Classic (AD 422–531, but we obtained different archaeomagnetic dates for the red pigment layers found in the buildings of the Pequeña Acrópolis and thus we were able to determine their chronological order of construction. The raw materials and proportions were carefully chosen to fulfil the mechanical necessities of the architectonic function: different proportions were found in plasters of floors, in the external walls, and inside the buildings; differences between earlier and later plasters were also detected.

Materiales Maria Maya: community-based materials development.

Science.gov (United States)

Moran, B C

1982-01-01

Materials Maria Maya (MMM) is a Guatemalan organization which has dedicated itself to making health education more relevant to the rural Mayans who constitute the majority of Guatemala's population. The administration and direction of the project is in the hands of a team of qualified Mayan men and women. Funding is primarily through various charitable international organizations. The content of preexisting health education programs, strongly influenced by the dominant "ladino" Spanish speaking culture was found to be inappropriate to the goal of this program. MMM set about to formulate a new teaching format which would draw upon, rather than trample over, established cultural practices and life styles. By a process of trial and error, involving small scale field tests, a new program format was developed. By questioning local women about perceived priority areas, through the study of morbidity and mortality data, decisions were made as to topics to be covered. Investigators, authors, and artists worked together to form a "materials package" which was then subject to pretesting. Out of this effort, MMM has been able to come up with a method to encourage more effective participative teaching through the use of education materials.

Digestive Physiology of Octopus maya and O. mimus: Temporality of Digestion and Assimilation Processes

Science.gov (United States)

Gallardo, Pedro; Olivares, Alberto; Martínez-Yáñez, Rosario; Caamal-Monsreal, Claudia; Domingues, Pedro M.; Mascaró, Maite; Sánchez, Ariadna; Pascual, Cristina; Rosas, Carlos

2017-01-01

Digestive physiology is one of the bottlenecks of octopus aquaculture. Although, there are successful experimentally formulated feeds, knowledge of the digestive physiology of cephalopods is fragmented, and focused mainly on Octopus vulgaris. Considering that the digestive physiology could vary in tropical and sub-tropical species through temperature modulations of the digestive dynamics and nutritional requirements of different organisms, the present review was focused on the digestive physiology timing of Octopus maya and Octopus mimus, two promising aquaculture species living in tropical (22–30°C) and sub-tropical (15–24°C) ecosystems, respectively. We provide a detailed description of how soluble and complex nutrients are digested, absorbed, and assimilated in these species, describing the digestive process and providing insight into how the environment can modulate the digestion and final use of nutrients for these and presumably other octopus species. To date, research on these octopus species has demonstrated that soluble protein and other nutrients flow through the digestive tract to the digestive gland in a similar manner in both species. However, differences in the use of nutrients were noted: in O. mimus, lipids were mobilized faster than protein, while in O. maya, the inverse process was observed, suggesting that lipid mobilization in species that live in relatively colder environments occurs differently to those in tropical ecosystems. Those differences are related to the particular adaptations of animals to their habitat, and indicate that this knowledge is important when formulating feed for octopus species. PMID:28620313

Iodide uptake by negatively charged clay interlayers?

International Nuclear Information System (INIS)

Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

2015-01-01

Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI (aq) ) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. - Highlights: • Iodide sorption experiments were completed with a diverse array of clay minerals. • Iodide uptake trended with CEC and swamping electrolyte identity and concentration. • Results can be explained by considering the formation of ion pairs in clay interlayers

Microbiological analysis of the in situ bitumen-nitrate-Opalinus clay interaction

International Nuclear Information System (INIS)

Moors, Hugo; Boven, Patrick; Leys, Natalie; Geissler, Andrea; Selenska-Pobell, Sonja

2012-01-01

Document available in extended abstract form only. Clay formations like the Opalinus Clay are foreseen to serve as the host rock for geological disposal of high and intermediate-level long-lived radioactive waste in several countries, because of their favourable properties to delay the migration of radionuclides over time. However, bituminized intermediate-level long-lived radioactive waste may physico-chemically perturb the clay barrier properties because in time it will leach substantial amounts of nitrate and organic bitumen degradation products (BDP). To study the physico-chemical impact of intermediate-level radioactive waste containing bitumen and nitrate, an in situ experiment in the Opalinus Clay (Saint Ursanne, Switzerland) named the Bitumen-Nitrate- Clay interaction (BN) experiment, is being performed at the Mont Terri Rock Laboratory. The in situ equipment of the BN-experiment consists of three separate packed-off intervals, supplied with a filter screen. Each interval is equipped with its own stainless steel water circulation unit. Such water circulation unit contains water sampling containers, circulation pumps and flow meters. One of the circulation units is equipped with an on-line UV spectrophotometer and pH electrode intervals, allowing a continuous monitoring of nitrate, nitrite concentrations, organic carbon level and pH. In a first series of tests, the microbial and biogeochemical effect of a nitrate and/or acetate perturbation is studied. Acetate is used as it a good representation of BDP. Hereto, nitrate was injected in interval 1 while a mixture of nitrate and acetate is injected in interval 2. As an active microbial community can have a significant impact on the physical and (geo)chemical conditions of the clay surrounding the disposal gallery, microbial analyses were performed on samples taken from the interval solutions before, during and after this first series of tests. Our microbial investigations which included Scanning Electron

Microbiological analysis of the in situ bitumen-nitrate-Opalinus clay interaction

Energy Technology Data Exchange (ETDEWEB)

Moors, Hugo; Boven, Patrick; Leys, Natalie [SCK.CEN, Institute for Environment, Health and Safety, Laboratory for Molecular and Cellular Biology, Boeretang 200, B-2400 MOL (Belgium); Geissler, Andrea; Selenska-Pobell, Sonja [Helmholtz Zentrum Dresden Rossendorf, Institute of Radiochemistry, Biogeochemistry, Bautzner Landstr. 400, D-01328 Dresden (Germany)

2012-10-15

Document available in extended abstract form only. Clay formations like the Opalinus Clay are foreseen to serve as the host rock for geological disposal of high and intermediate-level long-lived radioactive waste in several countries, because of their favourable properties to delay the migration of radionuclides over time. However, bituminized intermediate-level long-lived radioactive waste may physico-chemically perturb the clay barrier properties because in time it will leach substantial amounts of nitrate and organic bitumen degradation products (BDP). To study the physico-chemical impact of intermediate-level radioactive waste containing bitumen and nitrate, an in situ experiment in the Opalinus Clay (Saint Ursanne, Switzerland) named the Bitumen-Nitrate- Clay interaction (BN) experiment, is being performed at the Mont Terri Rock Laboratory. The in situ equipment of the BN-experiment consists of three separate packed-off intervals, supplied with a filter screen. Each interval is equipped with its own stainless steel water circulation unit. Such water circulation unit contains water sampling containers, circulation pumps and flow meters. One of the circulation units is equipped with an on-line UV spectrophotometer and pH electrode intervals, allowing a continuous monitoring of nitrate, nitrite concentrations, organic carbon level and pH. In a first series of tests, the microbial and biogeochemical effect of a nitrate and/or acetate perturbation is studied. Acetate is used as it a good representation of BDP. Hereto, nitrate was injected in interval 1 while a mixture of nitrate and acetate is injected in interval 2. As an active microbial community can have a significant impact on the physical and (geo)chemical conditions of the clay surrounding the disposal gallery, microbial analyses were performed on samples taken from the interval solutions before, during and after this first series of tests. Our microbial investigations which included Scanning Electron

Stools - pale or clay-colored

Science.gov (United States)

... gov/ency/article/003129.htm Stools - pale or clay-colored To use the sharing features on this page, please enable JavaScript. Stools that are pale, clay, or putty-colored may be due to problems ...

Mars, clays and the origins of life

Science.gov (United States)

Hartman, Hyman

1989-01-01

To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

Preparation of organophilic clays and polypropylene nano composites

International Nuclear Information System (INIS)

Lima, Martha Fogliato S.; Nascimento, Vinicius G. do; Lenz, Denise M.; Schenato, Flavia

2011-01-01

Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

Using maya chair during the expulsive phase of delivery and its relation to the lower incidence of episiotomy or perineal tears

Directory of Open Access Journals (Sweden)

Laura López Quirós

2014-04-01

Full Text Available The aims of this article is to present the results obtained from the development of a clinical question about using maya obstetric chair during the expulsive phase of delivery and its relation to the lower incidence of episiotomy and perineal tears. In traditional cultures, the women give birth naturally in vertical positions as kneeling, standing, among others. In Western societies, physicians have influenced women will deliver in the supine position, sometimes with legs raised using stirrups. For women of our country is difficult to adopt "alternative" positions that have traditionally been seen as 'normal'. The maya chair is used in the countries of South America, and it appears to be an effective way to prevent perineal tears and the lower incidence of episiotomy duringchildbirth. To carry out this secondary research methodology for clinical practice based on evidence that consists of five steps was used. A question was developed in PICO format (patient, intervention, comparison and observation, then an information search was performed in different databases like Ebsco Host, Google Scholar, PubMed, Medline plus, Embase. 30 articles were found, were analyzed according to the criteria set FCL version 2.0, of which only one was close to answering the clinical question. Information was socialized in a formalpresentation by CIEBE-CR. It is conclude that there is insufficient evidence that the use of maya chair during theexpulsive phase of delivery significantly reduces the risk of perianal tear and lower incidence of episiotomy.

Hydrogen isotope ratios of clay minerals constituting clay veins found in granitic rocks in Hiroshima Prefecture

International Nuclear Information System (INIS)

Kitagawa, Ryuji; Kakitani, Satoru; Kuroda, Yoshimatsu; Matsuo, Sadao; Suzuoki, Tetsuro.

1980-01-01

The deuterium content of the constitutional and interlayer water extracted from the clay minerals (illite, montmorillonite, interstratified illite-montmorillonite mineral, kaolinite, halloysite) constituting the clay veins found in the granitic rocks in Hiroshima Prefecture was measured. The clay minerals were heated at 270 deg C to extract the interlayer water, then heated to 1,400 or 1,500 deg C to extract the constitutional water. The deuterium content of the local surface water collected from sampling points was measured. In the clay veins formed along perpendicular joints, the constituent clay minerals change from lower to upper part: illite → montmorillonite → kaolinite → halloysite. The deuterium content values of the constitutional water for illite and montmorillonite were estimated to be -67 to -69% and -86 to -89%, respectively. The deuterium content values of the constitutional water for halloysite range from -68 to -80% and for kaolinite from -63 to -67%. (J.P.N.)

Quality of clay-powders of industrial assortment

Energy Technology Data Exchange (ETDEWEB)

Lityayeva, Z A; Dzetl, B G; Goncharenko, N N; Naurova, I V; Rybchenko, V I; Voyevodin, L I

1979-01-01

Nomenclature was developed for the quality indicators of clay powders which took into consideration the foreign experience, and it is suggested that a suspension of clay powders be viewed as the simplest type of drilling. In this case the technique of preparing the suspensions approaches the maximum to that used in the recommended standard (TU-39-043-074). The output of solution is determined with standardized effective viscosity /eta/ ef =/sup 20/ /SUP cP/ on a series domestic rotary viscosimeter VSN-3 with gradient of shear velocity EPSILON=666 sec/sup -1/; with EPSILON=1022 sec /sup -1//eta/ /SUB ef/ = 15 cP. This makes it possible to obtain data comparable to the foreign standards regarding the output of the fluid from the powders. According to the suggested technique, the clay powder is dispersed for 20-30 minutes in water or saturated solution of NaC1 in a mixing unit ''Voronezh2'' with rotation frequency of 9000 rpm, is left to rest and is again dispersed for 15 minutes. Then the dynamic shear stress (P /SUB k2/ ), plastic viscosity (/eta/ /SUB ef/ ), coefficients of coagulation (K /SUB c/ ) and thyxotropic (K /SUB T/ ) structure-formation are defined. Measurements are made on the instrument FLR-1 of water output with 0.7 (B) or 0.1 (B) MPa. According to this technique, a comparison was made of the domestic powders of industrial assortment with the powder ''Aquagel'' widely used abroad. It was established that only the modified concrete powders with correct selection of reagents can compete with the foreign.

La langosta, los mayas y el colonialismo en Yucatán, México, 1883

OpenAIRE

García Quintanilla, Alejandra

2012-01-01

En 1883 se produjo una gran plaga de langosta que afectó a diversos estados de la República Mexicana. Tuvo su origen en Yucatán. Aquí se analizan las respuestas sociales de la sociedad civil integrada mayoritariamente por personas mayas, la de los hacendados henequeneros y también la del gobierno de Yucatán en lo que fue el inicio del llamado Auge Henequenero. In the year 1883, an enormous plague of locusts emerged in Yucatán and then spread out to raze several states in the Mexican Republ...

Pedological ~cterization, Clay Mine:at~ and .~cation of,

African Journals Online (AJOL)

namely, very deep, well drained, dark reddish brown to dark brown, sandy clay loams and sandy clays on the steep convex slopes; very deep, well drained, dark brown to dark red, sandy clay loams and; sandy clays on the linear slopes; and very ...

Chemistry of the Marlboro Clay in Virginia and Implications for the Paleocene-Eocene Thermal Maximum

Science.gov (United States)

Zimmer, M.; Cai, Y.; Corley, A.; Liang, J. A.; Powars, D.; Goldstein, S. L.; Kent, D. V.; Broecker, W. S.

2017-12-01

The Paleocene-Eocene Thermal Maximum (PETM) was a global hyperthermal ( 5ºC warming) event marked by a rapid carbon isotope excursion (CIE) of >1‰ in the marine carbonate record (e.g. Zeebe et al. Nature Geoscience 2009). Possible explanations for the CIE include intrusion of a sill complex into organic carbonate (Aarnes et al. J. Geol. Soc. 2015), dissolution of methane hydrates (Thomas et al. Geology 2002), and a comet impact event (Schaller et al. Science 2016). Here we present new data across the PETM from the VirginiaDEQ-USGS Surprise Hill (SH) core, Northumberland Co., VA. We analyzed the Marlboro Clay, a thick, kaolinite-rich clay unit that marks the initiation of the PETM in the mid-Atlantic Coastal Plain of North America, as well as units above and below it. Bulk sediment records a δ13C excursion of approximately -5‰ across the CIE, while benthic foraminifera (Cibicidoides spp.) record a synchronous excursion of approximately -4.5‰. These results are consistent with other records from the New Jersey Coastal Plain (Makarova et al. Paleoceanography 2017). The excursion coincides with an increase in magnetic susceptibility, a decrease in bulk CaCO3 content, and an 2.5‰ decrease of δ18O in both the bulk sediment and benthic foraminifera of the SH core. Pb isotope analyses of the fraction sediments indicate a unique provenance make-up for the Marlboro Clay. The results of the study thus indicate that PETM Marlboro Clay was not generated simply by intensified weathering of the same source area as the underlying Aquia Formation and overlying Nanjemoy Formation. Any hypothesis that aims to explain the mechanism that triggered the PETM must also account for the observed distinct provenance make-up of the Marlboro Clay.

Preparation and characterization of bentonite organo clay

International Nuclear Information System (INIS)

Bertagnolli, C.; Almeida Neto, A.F.; Silva, M.G.C.

2009-01-01

Bentonite clays organically modified have great potential use for environmental remediation, especially in the separation of organic compounds from the water. The aim of this work was the preparation of organophilic clays from 'Verde-Lodo' bentonite clay with the quaternary ammonium salts cetyl-pyridinium chloride and benzalkonium chloride. The materials obtained were characterized by XRD, thermogravimetric analyses, Helium picnometry, SEM and energy dispersive X-ray techniques. The results show consistently successful synthesis of the organoclay through the increase in the basal spacing, as well as salt elimination picks and presence of carbon and chlorine in the modified clays; they are inexistent elements in the natural clay. (author)

Treatment for cracked and permeable Houston clay

International Nuclear Information System (INIS)

Vipulanandan, C.; Leung, M.

1991-01-01

In this study, the treatability of a field clay (obtained from Houston, Texas) and a clay-sand mixture to reduce their hydraulic conductivity was evaluated. Remolded field clay and clay-sand mixture with and without methanol contamination were treated to reduce their hydraulic conductivity by permeating very dilute grout solutions. The concentration of sodium silicate in the grout solution was 8%, while the solid content in the cement grout was 0.3%. The hydraulic conductivity of permeable Houston clay (hydraulic conductivity >10 -5 cm/sec) could be reduced to less than 10 -7 cm/sec (U.S. EPA limit for soil barriers) by permeating with a selected combination of grout solutions

Characterization of clay used for red ceramic fabrication

International Nuclear Information System (INIS)

Pereira, P.S.; Morais, A.S.C.; Caldas, T.C.C.; Monteiro, S.N.; Vieira, C.M.F.

2011-01-01

The objective of this work is to characterize a clay used in the red ceramics fabrication, from Campos dos Goytacazes north of the State of Rio de Janeiro. The clay was submitted for physical, chemical and mineralogical tests. The results showed that the clay has a high content of clay minerals with kaolinitic predominance, high loss on ignition and low flux oxides. It is recommended that this clay is mixed with non-plastic materials. (author)

Encapsulation of Clay Platelets inside Latex Particles

NARCIS (Netherlands)

Voorn, D.J.; Ming, W.; Herk, van A.M.; Fernando, R.H.; Sung, Li-Piin

2009-01-01

We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

Science.gov (United States)

Moran, Anthony R.; Hettiarachchi, Hiroshan

2011-01-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

Science.gov (United States)

Moran, Anthony R; Hettiarachchi, Hiroshan

2011-07-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

Directory of Open Access Journals (Sweden)

Anthony R. Moran

2011-06-01

Full Text Available Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

José Martí, Viajes y Apreciación del Pueblo Maya

Directory of Open Access Journals (Sweden)

Carlos Eduardo Bojórquez Urzaiz

2015-09-01

Full Text Available Este trabajo expone y examina los cambios de percepción que experimentó José Martí sobre el papel de los pueblos originarios de América, entre 1875 y 1878, años en los que vivió en México y Guatemala, con intensa escala en Yucatán, lugares donde conoció directamente la cultura y el pueblo maya. Martí resume una visión inicial de nuestra América en la figura lítica de Chacmool cuando después de ser expropiada por el gobierno yucateco, el Apóstol cubano la admira en la ciudad de Mérida y expresa que es la síntesis de las culturas americanas. Aspecto poco estudiado en la obra de Martí es este acercamiento etnográfico a la realidad maya de Yucatán y Guatemala.   This paper aims at presenting and examining the change of perception José Martí underwent in relation to the role of the native peoples of America between 1875 and 1878, the years he lived in Mexico and Guatemala, during which he spent a large amount of time in Yucatan, where he was able to get to know the Mayan culture and its people first hand. Martí summarized his initial vision of our America in the lithic figure of Chacmool, which he was able to admire in the city of Merida, after it had been expropriated by the government of Yucatan. The Cuban apostle described this as a synthesis of American cultures. This ethnographic insight into the Mayan reality in Yucatan and Guatemala represents a scarcely explored aspect of Martí's work.

Sorption of Pu onto some kinds of clay

International Nuclear Information System (INIS)

Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

2010-01-01

There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

Rheological characterization of nanocomposites Nylon 6/bentonite clay

International Nuclear Information System (INIS)

Silva, T.R.G.; Fernandes, P.C.; Oliveira, S.V.; Araujo, E.M.; Melo, T.J.A.

2010-01-01

Polymer nanocomposites are a class of materials that have been widely used in various applications. Among them, has been emphasizing the preparation of polymer films with barrier properties for applications in polymer membranes. In this work, nanocomposites of nylon 6/bentonite clay were obtained from a Homogenizer, in the ratios of 1, 3 and 5 wt% clay. The Brasgel PA bentonite clay was treated organically with Praepagen HY salt, to make it organophilic. By X-ray diffraction (XRD), it was showed that the efficiency of the incorporation of salt in the clay. The rheological curves showed that for the AST clay the torque did not change when compared with the pure nylon 6, while for the clay ACT, the torque increased gradually with the percentage of clay. (author)

Polymer-clay nanocomposites obtained by solution polymerization ...

Indian Academy of Sciences (India)

Clay minerals can be found all over the world.1 Clay minerals have ... salts or covalent bonding with silanes at the OH edges of the clay. ..... Marras S I, Tsimpliaraki A, Zuburtikudis I and ... Mansoori Y, Roojaei K, Zamanloo M R and Imanzadeh.

Hydro-mechanical properties of the red salt clay (T4) - Natural analogue of a clay barrier

International Nuclear Information System (INIS)

Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Boettge, V.

2010-01-01

Document available in extended abstract form only. Long-term storage of high-level radioactive waste in deep geologic formations is worldwide the only accepted solution to warranty long term safety. Besides clay and crystalline rocks, salt is one of the potential host-rock candidates, mainly favored in Germany. As salts rocks are highly soluble their barrier integrity against water inflow from the cap rock is questionable. Argillaceous cap rocks or intercalated clay layers may act as protective shield in the hanging wall above a repository, thus providing a multi-barrier system. The aims of our study are twofold: 1) to characterize the mineralogical, hydraulic and rock-mechanical properties of the so-called Red Salt Clay (T4) as natural analogue of a clay barriers represented by different states of induration corresponding to various depth of burial diagenesis; 2) to demonstrate the favoured barrier properties of an argillaceous layer in the top of a salt formation undergoing dynamic processes such as rock bursts. The so-called Red Salt Clay (T4) is deposited as clay rich clastic sediment at the base of the Aller-series forming a persistent lateral layer above the lower Zechstein-series. The thickness of the clay-formation becomes smaller with decreasing distance from the border of the basin, i.e. from ∼15 m at Rossleben, over 7 m at Bernburg to 3.5 m at Zielitz, all in Saxony-Anhalt, D). The mineralogical composition of the Red Salt Clay varies, e.g. average composition for the Teutschenthal area: clay minerals 54% (Chlorite: 8%; Illite/Muscovite: 46%); quartz: 22%; anhydrite: 15%; accessory gypsum; Halite: 6%, Hematite: ∼ 2%). The geochemical and mineralogical composition of the Red Salt Clay represents a final state of natural salt-clay-systems, thus standing as a natural analogue for bentonite-based sealing systems in contact with high-saline solutions (e.g. saturated NaCl-solution, solutions with various Mg 2+ -, K + -, SO 4 2- - concentrations). The

Utilization of Nkpuma-Akpatakpa clay in ceramics: characterization ...

African Journals Online (AJOL)

Nkpuma – Akpatakpa clay was analysed for its ceramics suitability. Chemical, mechanical and spectral characterization of the clay was carried out to obtain more information from this clay found in commercial quantity at Ebonyi State Nigeria. The XRD analysis showed that the principal minerals in the clay are quartz, ...

Preparation and properties of recycled HDPE/clay hybrids

Science.gov (United States)

Yong Lei; Qinglin Wu; Craig M. Clemons

2007-01-01

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

Iodide uptake by negatively charged clay interlayers?

Science.gov (United States)

Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

2015-09-01

Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Limites politiques et barrières sociales dans le monde maya classique Political Limits and Social Barriers in the Classic Maya World: Reflections Based on a Few Archaeological Experiences

Directory of Open Access Journals (Sweden)

Dominique Michelet

2012-12-01

Full Text Available L’archéologie des Basses Terres mayas à l’époque classique est riche de données susceptibles de nous renseigner sur plusieurs types de « frontières » sociopolitiques. Si la question des limites territoriales des entités politiques du monde classique constitue, depuis les années 1970, un objectif tout à fait conscient de la recherche, bien d’autres éléments des partitionnements sociopolitiques existent, mais ils n’ont pas reçu, le plus souvent, l’attention qu’ils méritent. L’examen de quelques informations, empruntées aux résultats de projets de recherche collective récents, indique que les démarcations formelles plus ou moins minces durent être rares, qu’il y aurait même eu peu de bornages explicites et que les seuils étaient dotés d’une épaisseur certaine, leur franchissement obéissant à des codes précis et/ou impliquant des comportements ritualisés.The archaeology of the Maya Lowlands of the classical era is rich in data that are likely to have something to teach us about several types of sociopolitical “boundary”. Although research since the 1970s has consciously aimed to address the question of the territorial limits of classical-world political entities, many other elements of sociopolitical partitioning exist, but they have tended not to receive the attention they deserve. The examination of a few pieces of information, borrowed from the results of recent collective research projects, indicates that more-or-less thin formal demarcations must have been rare, that there would even have been few explicit boundary markings, and that the thresholds were endowed with a certain thickness, their crossing obeying precise codes and/or involving ritualised behaviours.

Experimental Support for a Predictive Osmotic Model of Clay Membranes

International Nuclear Information System (INIS)

Fritz, S.J.

2001-01-01

Osmosis has been cited as a mechanism for explaining anomalously high fluid pressures in the subsurface. Clays and shales act as membranes, and osmotic flux across these units may result in pressures sufficiently high to explain these anomalies. The theoretical osmotic pressures as calculated solely from solution properties can be quite large; however, it is not yet resolved whether these geologic membranes are sufficiently ideal to generate such pressures

generalized constitutive model for stabilized quick clay

African Journals Online (AJOL)

QUICK CLAY. PANCRAS MUGISHAGWE BUJULU AND GUSTAV GRIMSTAD. ABSTRACT. An experimentally-based two yield surface constitutive model for cemented quick clay has been ... Clay Model, the Koiter Rule and two Mapping Rules. .... models, where a mobilization formulation is used, this is independent of q.

Processes of cation migration in clay-rocks: Final Scientific Report of the CatClay European Project

International Nuclear Information System (INIS)

Altmann, S.; Aertsens, M.; Appelo, T.; Bruggeman, C.; Gaboreau, S.; Glaus, M.; Jacquier, P.; Kupcik, T.; Maes, N.; Montoya, V.; Rabung, T.; Robinet, J.-C.; Savoye, S.; Schaefer, T.; Tournassat, C.; Van Laer, L.; Van Loon, L.

2015-07-01

In the framework of the feasibility studies on the radioactive waste disposal in deep argillaceous formations, it is now well established that the transport properties of solutes in clay rocks, i.e. parameter values for Fick's law, are mainly governed by the negatively charged clay mineral surface. While a good understanding of the diffusive behaviour of non-reactive anionic and neutral species is now achieved, much effort has to be placed on improving understanding of coupled sorption/diffusion phenomena for sorbing cations. Indeed, several cations known to form highly stable surface complexes with sites on mineral surfaces migrate more deeply into clay rock than expected. Therefore, the overall objective of the EC CatClay project is to address this issue, using a 'bottom-up' approach, in which simpler, analogous systems (here a compacted clay, 'pure' illite) are experimentally studied and modelled, and then the transferability of these results to more complex materials, i.e. the clay rocks under consideration in France, Switzerland and Belgium for hosting radioactive waste disposal facilities, is verified. The cations of interest were chosen for covering a representative range of cations families: from a moderately sorbing cation, the strontium, to three strongly sorbing cations, Co(II), Zn(II) and Eu(III). For the 4 years of this project, much effort was devoted to developing and applying specific experimental methods needed for acquiring the high precision, reliable data needed to test the alternative hypotheses represented by different conceptual-numerical models. The enhanced diffusion of the sorbing cations of interest was confirmed both in the simpler analogous illite system for Sr 2+ , Co(II) and Zn(II), but also in the natural clay rocks, except for Eu(III). First modelling approach including diffusion in the diffuse double layer (DDL) promisingly succeeded in reproducing the experimental data under the various conditions both in

Two new nematodes from the Iriomote cat, Prionailurus iriomotensis, from Okinawa: Uncinaria (Uncinaria) maya n. sp. (Ancylostomatoidea) and Molineus springsmithi yayeyamanus n. subsp. (Trichostrongyloidea).

Science.gov (United States)

Hasegawa, H

1989-12-01

Uncinaria (Uncinaria) maya n. sp. (Nematoda: Ancylostomatidae) and Molineus springsmithi yayeyamanus n. subsp. (Nematoda: Molineidae) are described from the Iriomote cat, Prionailurus iriomotensis, on Iriomote Island, Okinawa, Japan. Uncinaria (U.) maya resembles Uncinaria (Uncinaria) felidis Maplestone, 1939, from Prionailurus bengalensis of India but is distinguished in that the body is much smaller, the ventral rays are set closely with the lateral rays, and the externolateral ray is much shorter than other laterals. Molineus springsmithi yayeyamanus differs from Molineus springsmithi springsmithi Inglis and Ogden, 1965, from Prionailurus bengalensis horsfieldi of East Nepal in that the body is much longer, whereas the esophagus is somewhat shorter and the spicules are divided more distally. Presence of the closely related nematodes in both the Iriomote cat and P. bengalensis suggests a close evolutionary relationship of the 2 hosts.

Measurement of the GMR in the Unstable 56Ni Nucleus using the Active Target Maya

International Nuclear Information System (INIS)

Monrozeau, C.; Khan, E.; Blumenfeld, Y.; Mittig, W.; Beaumel, D.; Caamano, M.; Cortina-Gil, D.; Demonchy, C.E.; Frascaria, N.; Garg, U.; Gelin, M.; Gillibert, A.; Gupta, D.; Marechal, F.; Obertelli, A.; Roussel-Chomaz, P.; Scarpaci, J.-A.

2007-01-01

The measurement of the Isoscalar Giant Monopole Resonance(GMR) in unstable nuclei remains a major experimental challenge due to low radioactive beam intensities and unfavourable conditions in reverse kinematics. At GANIL, we have tested a new experimental method based on the unique capabilities of the active target Maya to probe the GMR by the inelastic scattering reaction 56 Ni(d,d') at 50 AMeV. The preliminary excitation energy spectrum of 56 Ni presents a bump between 12 and 25 MeV where isoscalar resonances are expected

Clay-Enriched Silk Biomaterials for Bone Formation

Science.gov (United States)

Mieszawska, Aneta J.; Llamas, Jabier Gallego; Vaiana, Christopher A.; Kadakia, Madhavi P.; Naik, Rajesh R.; Kaplan, David L.

2011-01-01

The formation of silk protein/clay composite biomaterials for bone tissue formation is described. Silk fibroin serves as an organic scaffolding material offering mechanical stability suitable for bone specific uses. Clay montmorillonite (Cloisite ® Na+) and sodium silicate are sources of osteoinductive silica-rich inorganic species, analogous to bioactive bioglass-like bone repair biomaterial systems. Different clay particle-silk composite biomaterial films were compared to silk films doped with sodium silicate as controls for support of human bone marrow derived mesenchymal stem cells (hMSCs) in osteogenic culture. The cells adhered and proliferated on the silk/clay composites over two weeks. Quantitative real-time RT-PCR analysis revealed increased transcript levels for alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col I) osteogenic markers in the cells cultured on the silk/clay films in comparison to the controls. Early evidence for bone formation based on collagen deposition at the cell-biomaterial interface was also found, with more collagen observed for the silk films with higher contents of clay particles. The data suggest that the silk/clay composite systems may be useful for further study toward bone regenerative needs. PMID:21549864

Influence of non-clay minerals on the interaction between metallic iron and Callovo-Oxfordian clay fraction

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Villieras, F.; Michau, N.

2012-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste, it is of prime importance to understand the interaction mechanisms between the geological matrix, Callovo-Oxfordian clay rock (COx) and metallic iron, from the package overpack. In order to evidence the individual role of each clay component entering in the mineralogy of the COx, interactions between metallic iron and pure clays (smectites, illite and kaolinite) were first conducted. To investigate the role of the other minerals, the reactivity of COx, COx clay fraction (COxCF) and mixtures between COxCF and quartz, calcite or pyrite, was studied. Clays and additional minerals were put in contact with powder metallic iron with a weight ratio iron:clay fixed at 1:3 and a clay:solution ratio of 1:20. Proportions of non-clay minerals were deduced from the average COx composition: 50% clays, 24.5% quartz, 24.5% calcite and 1% pyrite. Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) in Parr reactors for durations of one, three or nine months. After reaction, solid and liquid phases were separated by centrifugation and characterized by classical techniques combining chemical analyses (liquid analyses, transmission electron microscopy combined with Energy Dispersive of X-rays spectroscopy TEM-EDS), mineralogical (X-ray diffraction), spectroscopic ( 57 Fe Moessbauer) and morphometric techniques (TEM, scanning electron microscopy and N 2 adsorption). For COx, COxCF and all the pure clay phases, major evolutions were observed during the first month, which shows that the oxidation of metallic iron is rapid in our experimental conditions. Release of iron cations in solution, pH increase (8-10) and Eh decrease (reductive conditions) are responsible for the partial dissolution of initial clay phases. Released iron is involved in the crystallization of Fe

Strength Properties of Aalborg Clay

DEFF Research Database (Denmark)

Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

glacial time are characterised by the absence of this mussel. These deposits are named Aalborg Clay and Aalborg Sand. In the city of Aalborg, a fill layer superposes Aalborg Clay. This layer is at some places found to be 6m thick. This fill layer does not provide sufficient bearing capacity, which has...... resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...

Mechanical interaction between swelling compacted clay and fractured rock, and the leaching of clay colloids

NARCIS (Netherlands)

Grindrod, P.; Peletier, M.A.; Takase, H.

1999-01-01

We consider the interaction between a saturated clay buffer layer and a fractured crystalline rock engineered disturbed zone. Once saturated, the clay extrudes into the available rock fractures, behaving as a compressible non-Newtonian fluid. We discuss the modelling implications of published

1st International Conference on Calcined Clays for Sustainable Concrete

CERN Document Server

Favier, Aurélie

2015-01-01

This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

Interphase vs confinement in starch-clay bionanocomposites.

Science.gov (United States)

Coativy, Gildas; Chevigny, Chloé; Rolland-Sabaté, Agnès; Leroy, Eric; Lourdin, Denis

2015-03-06

Starch-clay bionanocomposites containing 1-10% of natural montmorillonite were elaborated by melt processing in the presence of water. A complex macromolecular dynamics behavior was observed: depending on the clay content, an increase of the glass transition temperature and/or the presence of two overlapped α relaxation peaks were detected. Thanks to a model allowing the prediction of the average interparticle distance, and its comparison with the average size of starch macromolecules, it was possible to associate these phenomena to different populations of macromolecules. In particular, it seems that for high clay content (10%), the slowdown of segmental relaxation due to confinement of the starch macromolecules between the clay tactoïds is the predominant phenomenon. While for lower clay contents (3-5%), a significant modification of chain relaxation seems to occur, due to the formation of an interphase by the starch macromolecules in the vicinity of clay nanoparticles coexisting with the bulk polymer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soil clay content underlies prion infection odds

Science.gov (United States)

David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

2011-01-01

Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

Clay bricks prepared with sugarcane bagasse and rice husk ash – A sustainable solution

Directory of Open Access Journals (Sweden)

Azhar Saleem Muhammad

2017-01-01

Full Text Available This study aims to characterize the clay bricks produced by the addition of the two agricultural waste materials i.e. sugarcane bagasse and rice husk ash. Disposing off these waste materials is a very challenging task and is a hazard to environment. The sugarcane bagasse and rice husk ash were collected locally from the cities of Peshawar and Wazirabad, respectively. These were mixed with the clay for brick manufacturing in three different proportions i.e. 5, 10 and 15% by weight of clay. Mechanical i.e. compressive strength and modulus of rupture and durability properties i.e. water absorption; freeze-thaw and sulphate resistance of these bricks were evaluated. Test results indicated that the sulphate attack resistance and efflorescence of clay bricks incorporating sugarcane bagasse and rice husk ash have been increased significantly. However, no significant effect on mechanical properties was observed. Furthermore, the additions of wastes have reduced the unit weight of bricks which decrease the overall weight of the structure leading to economical construction. Therefore, it can be concluded that the addition of waste materials in brick manufacturing can minimize the environmental burden leading towards more economical and sustainable construction.

Radiation synthesis and characterization of thermo-sensitive PNIPA/clay hydrogels

International Nuclear Information System (INIS)

Song Hongyan; He Suqin; Liu Wentao; Zhu Chengshen; Yang Mingcheng

2007-01-01

In this work, the thermo-sensitive hydrogels of PNIPA/Clay were synthesized by 60 Co-γ rays irradiation. The effects of organically modified clay and Na + clay, clay content, and dispersing condition on swelling behavior of PNIPA/clay hydrogels were investigated. The results showed that the equilibrium swelling ratio (SR) of the PNIPA/clay hydrogels is better than PNIPA, and the SR of PNIPA/organically modified clay hydrogels is the highest. With clay content increases, the SR of hydrogels became better. The deswelling behavior of hydrogel was improved, the deswelling ratio of the hydrogel with organically modified clay is highest, and ratio of losing water is 83%, while PNIPA is about 50%. The compressive properties of hydrogel composites were also examined. The results showed that the compressive properties of the PNIPA/clay hydrogels were improved distinctly than that of the conventional hydrogels without clay. And with increasing of clay content, the compressive properties of hydrogel composites improve rapidly. When the content of clay is 15%, the maximum compression force of the PNIPA/clay hydrogel is 5.28N, which is 14 times of PNIPA hydrogel and compression strength is 2.5 times. (authors)

A mask for high-intensity heavy-ion beams in the MAYA active target

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Tajes, C., E-mail: rodriguez@ganil.fr [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Pancin, J.; Damoy, S.; Roger, T.; Babo, M. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Caamaño, M. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Farget, F.; Grinyer, G.F.; Jacquot, B.; Pérez-Loureiro, D. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Ramos, D. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Suzuki, D. [Institut de Physique Nucléaire, Université Paris-Sud 11, CNRS/IN2P3, F-91406 Orsay (France)

2014-12-21

The use of high-intensity and/or heavy-ion beams in active targets and time-projection chambers is often limited by the strong ionization produced by the beam. Besides the difficulties associated with the saturation of the detector and electronics, beam-related signals may hide the physical events of interest or reduce the detector performance. In addition, space-charge effects may deteriorate the homogeneity of the electric drift field and distort the subsequent reconstruction of particle trajectories. In anticipation of future projects involving such conditions, a dedicated beam mask has been developed and tested in the MAYA active target. Experimental results with a {sup 136}Xe beam are presented.

Paleomagnetism of the Todos Santos Formation in the Maya Block, Chiapas, Mexico: Preliminary Results

Science.gov (United States)

Godinez-Urban, A.; Molina-Garza, R. S.; Iriondo, A.; Geissman, J. W.

2008-12-01

Preliminary results of a paleomagnetic study on jurassic volcanic rocks (U-Pb 188.8 +/- 3.2Ma) locally interbedded with red beds assigned to the Todos Santos Formation, sampled in the Homoclinal Tectonic Province of the Neogene Fold Belt, Chiapas-Mexico, reveal multi component magnetizations acquired during pre- and post- folding of these rocks. The samples responded well to thermal demagnetization, but not so to AF demagnetization, suggesting that a high coercivity mineral phase like hematite is the main remanence carrier. The post-folding B-component direction of Dec=174.3 Inc=-30.6 (k=46; alpha95=13.6; N=4) represents a recent Tertiary? overprint; while the pre-folding C-component direction of Dec=329.9 Inc=7.8 (k=12.5; alpha95=16.3; N=8) is in agreement with a previously reported small data set for the Todos Santos Formation. When compared to the North American reference direction (Jurassic Kayenta Formation) the observed direction indicates a counterclockwise rotation of 35.9 +/- 16.6 degrees, and moderate north to south latitudinal displacement. If a reference pole from NE North America is used, the amount of counterclockwise rotation and latitudinal displacement are both slightly reduced. If the assumption that Jurassic strata in Chiapas reflect displacement of the Maya Block, then these data are consistent with reconstructions of the Maya Block in the Gulf of Mexico region. Other sites sampled in Jurassic strata suggest that in addition to the interpreted regional rotation, local (vertical-axis) rotations may have affected the region in more recent times.

Criticisms of chlorination: social determinants of drinking water beliefs and practices among the Tz'utujil Maya.

Science.gov (United States)

Nagata, Jason M; Valeggia, Claudia R; Smith, Nathaniel W; Barg, Frances K; Guidera, Mamie; Bream, Kent D W

2011-01-01

To explore social determinants of drinking water beliefs and practices among the Tz'utujil Maya of Santiago Atitlán, Guatemala, through analysis of demographics, socioeconomic status, memory of historical events, sensory experience, and water attitudes. Parallel mixed (qualitative and quantitative) methods, including participant observation, in-depth interviews based on a purposive sample, and 201 semi-structured interviews based on a regional quota sample, were used to collect data from March 2007 to August 2008. Data analysis included the use of grounded theory methodology and Pearson's chi-square test for independence. Qualitative results based on grounded theory highlighted how memory of the Guatemalan Civil War and Hurricane Stan, attitudes about Lake Atitlán water, and the taste and smell of chlorine influenced Tz'utujil Maya drinking water beliefs. Quantitative survey results revealed that differences in ethnicity, literacy, years of schooling, distrust of the water supply during the Civil War and Hurricane Stan, and current beliefs about Lake Atitlán and tap water quality were associated with significantly different water self-treatment practices. In accordance with social determinants of health paradigms, demographic, socioeconomic, social, cultural, political, and historical factors continue to be significant determinants of water-related health. Public health water interventions must address inequalities related to these underlying factors in order to achieve maximum effectiveness.

Pacoma: Performance assessment of the confinement of medium-active and alpha-bearing wastes. Assessment of disposal in a clay formation in the United Kingdom

International Nuclear Information System (INIS)

Mobbs, S.F.; Klos, R.A.; Martin, J.S.; Laurens, J.M.; Winters, K.H.

1991-01-01

This report describes the PACOMA assessment of the radiological impact of disposal of intermediate level and alpha-bearing wastes in a hypothetical repository situated in the clay formations below the Harwell site in the United Kingdom. The assessment includes: best estimate calculations, uncertainty analyses, sensitivity analyses and model comparisons. Results of the radiological impact calculations are in the form of doses and risks to individuals and time-integrated doses to populations, for a normal evolution scenario and a number of altered evolution scenarios. The calculated risks to individuals are well below the limit recommended by the ICRP, and the calculated collective dose over the first 10,000 years after disposal is zero. Thus the radiological impact of the disposal intermediate level and alpha-bearing wastes in a clay formation is predicted to be small. The uncertainty analyses showed that, for the normal evolution scenario, the range of predicted risks to individuals is very wide. However, these results must be treated with caution because a formal methodology for eliciting judgments about model parameter values was only applied in the case of geosphere data. The sensitivity analyses and model comparisons indicated the need for improved models and data for water and radionuclide movement in the near-surface environment

Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (Volume 1)

International Nuclear Information System (INIS)

Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

1991-01-01

The results of two years of research on thermomechanics of clays performed within CEC contract Fl1W/0150 are described herein. Previous studies (research contracts with CEC/WAS/380.83.7 l) performed by ISMES have evidenced the need for an improved modelling of the volumetric response of natural clays. In a coupled approach, this leads to an improved prediction of pore-pressure development and dissipation. This is crucial for assessing conditions of a possible local thermal failure as verified in laboratory tests done at ISMES. The first part of the study lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton. It consists in: (a) developing a framework for inclusion of water/soil particle thermally induced interaction into a thermodynamically consistent mixture theory approach (Section 2); (b) studying possible modelling approaches of considering the effective thermal expansion coefficient of pore water dependency on pore water status (Section 2); (c) testing artificial clays to assess pore water thermal expansion dependence on temperature in the presence of different amounts of active clay minerals and also Boom clay (Section 3); (d) performing a laboratory test campaign on Boom clay with special attention to the response in the overconsolidated domain (Section 4). 89 figs., 18 tabs., 102 refs

Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (volume 2)

International Nuclear Information System (INIS)

Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

1991-01-01

This study is composed of two parts: The first part (Volume 1) lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton during thermal dilatation. The second part (volume 2) is devoted to the development and the application of advance constitutive modelling of mechanical behaviour of clays taking into account the extensive tests of Boom clay reported in the first volume. The development concentrated on the improvement of prediction of the volumetric response of clay skeleton: (a) improving the dilatancy prediction at low to high overconsolidation ratios (Section 2). An elasto-plastic constitutive model has been developed to account for this effect (Section 3.2.); (b) modelling of swelling effects (Section 2.5). A preliminary interpretative model for swelling prediction has been developed (Section 2.5). The application part consisted in interpreting the experimental results obtained for Boom clay to calibrate a set of constants (Section 3) for performing numerical analyses (Section 4) for the thermomechanical model already calibrated for Boom clay (Appendix). Interpretation of the tests required an assessment of influence of the strong anisotropy effects revealed by Boom clay on the basis of an interpretative model characterized by a kinematic hardening plasticity and coupled elasticity (section 3)

Investigations of salt mortar containing saliferous clay

International Nuclear Information System (INIS)

Walter, F.

1992-01-01

Saliferous clay mortar might be considered for combining individual salt bricks into a dense and tight long-term seal. A specific laboratory program was started to test mortars consisting of halite powder and grey saliferous clay of the Stassfurt from the Bleicherode salt mine. Clay fractions between 0 and 45% were used. The interest focused upon obtaining good workabilities of the mixtures as well as upon the permeability and compression strength of the dried mortar samples. Test results: 1) Without loss of quality the mortar can be mixed using fresh water. Apprx. 18 to 20 weight-% of the solids must be added as mixing water. 2) The porosity and the permeability of the mortar samples increases distinctly when equally coarse-grained salt power is used for mixing. 3) The mean grain size and the grain size distribution of the saliferous clay and the salt powder should be very similar to form a useful mortar. 4) The permeability of the mortar samples decreases with increasing clay fraction from 2 10 -12 m 2 to 2 10 -14 m 2 . The investigated samples, however, were large and dried at 100degC. 5) The uniaxial compressive strength of the clay mortar equals, at an average, only 4 MPa and decreases clearly with increasing clay fraction. Moist mortar samples did not show any measurable compressive strength. 6) Moistened saliferous clay mortar may show little temporary swelling. (orig./HP)

Organic waste treatment with organically modified clays

International Nuclear Information System (INIS)

Evans, J.C.; Pancoski, S.E.; Alther, G.

1989-01-01

The use of organically modified clays in hazardous waste management applications offers a significant new and untapped potential. These clays may be used in the stabilization of organic wastes and organically contaminated soils, for waste water treatment, for oil spill control, for liner systems beneath fuel oil storage tanks, and as a component within liner systems of hazardous waste storage treatment and disposal facilities. Organically modified clays (organophilic clays) may be employed in each of these systems to adsorb organic waste constituents, enhancing the performance of the applications

Molecular dynamics of interfacial water and cations associated with clay minerals

International Nuclear Information System (INIS)

Cygan, Randall T.; Greathouse, Jeffery A.; Teich-McGoldrick, Stephanie L.; Nenoff, Tina M.; Daemen, Luke L.

2012-01-01

Document available in extended abstract form only. Clay mineral interfaces, including interlayer and external surfaces, play an essential role in many geochemical processes. Adsorption, dissolution, precipitation, nucleation, and growth mechanisms, in particular, are controlled by the interplay of structure, thermodynamics, kinetics, and transport at clay mineral-water interfaces. Molecular details of these geochemical processes are especially important in evaluating the fate of radionuclide waste in the environment. Such details are typically beyond the sensitivity of experimental and analytical methods and therefore require accurate models and simulations. Also, the basal surfaces and interlayers of clay minerals offer structurally constrained interfacial environments to better evaluate the local molecular chemistry. We have developed and used classical and quantum methods to examine the complex behavior of clay mineral-water interfaces and dynamics of interlayer species. Bulk structures, swelling behavior, diffusion, and adsorption processes are evaluated and compared to experimental and spectroscopic findings. In particular, inelastic neutron scattering methods provide a successful probe of vibrational behavior of interlayer species to help guide the simulations. Librations involving rock, wag, and twist motions of water molecules are particularly sensitive to the interlayer environment of smectite minerals such as montmorillonite and beidellite. Trends in librational modes for interlayer water as a function of clay structure and cation hydration energy are readily explained using structural and vibrational analysis derived from molecular simulation. Molecular dynamics simulations of virtual phases, including hydrated pyrophyllite, help to explain the behavior of interlayer water that is not associated with cation species. Additionally, we use large-scale molecular dynamics simulations of other layered minerals, such as muscovite, to evaluate adsorption

Compressibility characteristics of Sabak Bernam Marine Clay

Science.gov (United States)

Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

2018-04-01

This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

Fracture behavior of polypropylene/clay nanocomposites.

Science.gov (United States)

Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

2006-12-01

Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin; Ansari, Seema; Estevez, Luis; Hayrapetyan, Suren; Giannelis, Emmanuel P.; Lai, Hsi-Mei

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn't significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn\\'t significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Proceedings of the NEA Clay Club Workshop on Clay characterisation from nanoscopic to microscopic resolution

International Nuclear Information System (INIS)

2013-01-01

A wide spectrum of argillaceous media are being considered in Nuclear Energy Agency (NEA) member countries as potential host rocks for the final, safe disposal of radioactive waste, and/or as major constituent of repository systems in which wastes will be emplaced. In this context, the NEA established the Working Group on the 'Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations' in 1990, informally known as the 'Clay Club'. The Clay Club examines various argillaceous rocks that are being considered for the underground disposal of radioactive waste, ranging from soft clays to indurated shales. Very generally speaking, these clay rocks are composed of fine-grained minerals showing pore sizes from < 2 nm (micropores) up to > 50 nm (macro-pores). The water flow, solute transport and mechanical properties are largely determined by this microstructure, the spatial arrangement of the minerals and the chemical pore water composition. Examples include anion accessible ('geochemical') porosity and macroscopic membrane effects (chemical osmosis, hyper-filtration), geomechanical properties and the characteristics of two-phase flow properties (relevant for gas transport). At the current level of knowledge, there is a strong need to improve the nanoscale description of the phenomena observed at a more macroscopic scale. However, based on the scale of individual clay-minerals and pore sizes, for most of the imaging techniques this resolution is a clear challenge. The workshop, hosted by the Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT) in the Akademiehotel Karlsruhe (Germany) from 6 to 8 September 2011, was intended to give, inter alia, a discussion platform on: - The current state-of-the-art of different spectro-microscopic methods - New developments addressing the above mentioned knowledge gaps in clays. - The perception of the interplay between geometry

Single clay sheets inside electrospun polymer nanofibers

Science.gov (United States)

Sun, Zhaohui

2005-03-01

Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

Comparing uranyl sorption complexes on soil and reference clays

International Nuclear Information System (INIS)

Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

1993-01-01

Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

The compressive strength of lignosulphonate stabilised extruded earth masonry units

OpenAIRE

Maskell, Daniel; Walker, Pete; Heath, Andrew

2012-01-01

Earthen (unfired clay) bricks offer several distinct advantages over conventional fired clay bricks and other high energy masonry units. Most notably there is significantly lower environmental impact, including carbon emissions during manufacture, than comparable products, with unfired clay bricks having an estimated 14% of the energy of fired bricks and 25% of concrete blocks. Earth construction is able to provide passive environmental controls; including the regulation of temperature and hu...

Clay Cuffman: A Cool, Calm, Relaxed Guy

Science.gov (United States)

Booth, Gina

2010-01-01

This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

Hygrothermal behavior for a clay brick wall

Science.gov (United States)

Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

2018-06-01

In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

Hygrothermal behavior for a clay brick wall

Science.gov (United States)

Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

2018-01-01

In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

Knowledge of the Yucatec Maya in seasonal tropical forest management: the forage plants El conocimiento de los mayas yucatecos en el manejo del bosque tropical estacional: las plantas forrajeras

Directory of Open Access Journals (Sweden)

José Salvador Flores

2012-06-01

Full Text Available Indigenous knowledge and the millenary experience in management of natural vegetation on karstic landscapes are important aspects that should be considered in animal production in seasonal tropical environments. The aim of the present work was to make an inventory of native plants associated to soilscapes from seasonal tropical forests from the Yucatán Peninsula that are used as forage by Mayan people. The work was carried out in 27 Mayan communities on karst landscapes in the Yucatán Peninsula as a part of the "Ethnoflora Yucatanense" project of the Universidad Autónoma de Yucatán. Samples were taken of forage plants together with corresponding floristic and ethnobotanical information. Data were processed in EXCEL dynamic tables, grouped by plant family, geoforms and soils, life form and animal consumers. Results indicate that Mayan communities use 196 plant species as forage: 139 herbaceous, 17 shrubs, 35 trees and 2 palms. These plants are fed to cows, pigs, horses, lambs, turkeys, chickens, ducks and pigeons. The use of native forage plants may be an agricultural option both for rural communities and for intensive animal production on silvopastoral systems on karstic tropical landscapes from the Yucatán Peninsula.El conocimiento indígena y la experiencia de milenios de años en el manejo de la vegetación natural en ambientes kársticos tropicales son aspectos importantes que deben ser considerados en la producción animal. El objetivo de este trabajo fue hacer un inventario de las plantas forrajeras nativas de los bosques tropicales estacionales de la península de Yucatán que son utilizadas por los mayas, incluyendo los paisajes edáficos en los que se encuentran las plantas, información que servirá de base para la planeación de las actividades agropecuarias. El trabajo se llevó al cabo en 27 comunidades indígenas mayas, como parte del proyecto "Etnoflora Yucatanense" de la Universidad Autónoma de Yucatán. Las muestras de

Clay mineral facies and lateritization in basalts of the southeastern Parana Basin, Brazil

International Nuclear Information System (INIS)

Oliveira, M.T.G. de; Formoso, M.L.L.; Trescases, J.J.; Meunier, A.

1998-01-01

Seventeen samples from two lateritic profiles, each with five facies, were studied. These profiles occur on the old planation surface of the plateau basalts of the southern part of ParanáBasin, Brazil. Optical microscopy, X-ray diffraction, electron microprobe, Mössbauer spectroscopy and Fourier Transform Infrared Spectra were used to obtain information about the nature and chemical composition of each weathering facies. In addition, scanning electron microscopy and analyses of clay minerals were performed to detect microcrystalline environmental changes. Both profiles have two major parts: a loose red-clay latosol separated from an underlying mottled clay and an alterite facies; a stone line may or may not be present between the latosol and the underlying units. In both profiles the latosol consists principally of kaolinite, hematite and goethite. Two alterite facies, shaped by differential weathering, are also present in the lower profile: a halloysite–nontronite clayey matrix with a well developed fissure system occurs in the argillaceous alterite and a network of Al–goethite aggregates is typical of the highly porous cortex of the boulder alterite that is found in the stone line and below it. Gibbsite has crystallized in the large pores of porphyritic boulder alterite but is absent in the small pores of the subaphyric boulder alterite. Clay minerals observed in fissures include halloysite associated with goethite and manganese oxides. The basalt has hydrothermal green-clays (mixed layers and trioctahedral smectites) that formed between primary plagioclase, pyroxene and Ti–magnetite crystals while fresh corestones of the boulder alterite have cryptocrystalline iron-rich material. The study of these profiles shows one principal evolutionary trend for clay minerals. This trend is from smectite and mixed layers that form green clays in altered bedrock at the base of the profile to an intermediate association of nontronite and halloysite in the argillaceous

Some Tests on Heather Field Moraine Clay

DEFF Research Database (Denmark)

Jørgensen, Mogens B.; Jacobsen, Moust

This report deals with oedometer tests on three samples of moraine clay from the Heather Field in the English part of the North Sea. The tests have been carried out in the very unelastic apparatus used in Denmark and with special test procedures differing from the ones used elsewhere. In Denmark...... Moraine Clay covers a large part of the surface, and it has therefore been investigated extensively in the field and in the laboratories during the last 25 years. It is to day - from a geotechnical point of view - the best known clay in Denmark. It could therefore be of some interest to compare...... the English North Sea moraine clays with the corresponding Danish Moraine Clays. The Danish test procedures are explained in details and some comments are given in the hope that they may not be banalities all of them....

Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

Science.gov (United States)

Sarabadani, Hamid; Rayhani, Mohammad T

2014-06-01

Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

Distribution of clay minerals in the process streams produced by the extraction of bitumen from Athabasca oil sands

Energy Technology Data Exchange (ETDEWEB)

Kaminsky, H.A.W.; Etsell, T.H.; Ivey, D.G. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Omotoso, O. [Natural Resources Canada, Devon, AB (Canada). CETC

2009-02-15

The clay minerals present in the oil sands were studied with particular reference to how they are partitioned in bitumen ore during the extraction process. Bitumen production from surface-mined oil sands accounts for nearly two-thirds of the total bitumen production in Alberta. Every cubic meter of mined ore results in 1.3 cubic meters of mature fine tailings (MFT). The characteristic differences between the clay minerals that report to the froth versus the tailings streams were also examined to determine which minerals could impact different unit operations in the bitumen extraction process. X-ray diffraction and random powder samples were used to quantify the clay minerals. Particle size distribution and clay activity balances were also conducted. The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals. The water-continuous tailings stream was separated into fine and coarse tailings fractions through sedimentation. The study showed that bitumen-clay interactions may be dominated by kaolinite or iron oxides. Clays are responsible for the poor settling behaviour of MFTs. The clay minerals present in the oil sands include illite, illite-smectite, kaolinite, kaolinite-smectite, and chlorite. The close proximity of the tailings ponds to the Athabasca River and volatile organic compounds (VOCs) emission require that the ponds be reclaimed to a natural landscape before mine closure. In addition to its impact on fine tailings reclamation, clay mineralogy plays a role in extraction froth flotation and emulsion stability during froth treatment. The mineralogy of the froth solids was found to be different from the mineralogy of the middlings and tailings solids. 39 refs., 6 tabs., 6 figs.

Diffusion, sorption and stability of radionuclide-organic complexes in clays and clay-organic complexes

International Nuclear Information System (INIS)

Staunton, S.; Rees, L.V.C.

1991-01-01

The dependence on various parameters of the diffusion coefficient of neptunium (V) in clay systems has been studied. The effect of the clay mineralogy, the charge compensating cation in the clay, the ionic strength of a background perchlorate solution and the presence of three organic ligands have been investigated. The diffusion coefficients were compared to those predicted if diffusion occurred only in the liquid phase and adsorption was reversible; agreement was fairly good. An approximation to the diffusion coefficient can thus be obtained from readily measured experimental parameters. There is no evidence of surface phase diffusion. The most significant factor in determining the diffusion coefficient is the magnitude of the distribution ratio, itself highly dependent on the nature of the clay. Neither EDTA nor citrate modified the diffusion coefficient. Although the presence of 1 or 100 mg dm -3 of Aldrich humic acid had little effect on the distribution ratio of neptunium, it caused a lowering of the measured diffusion coefficient. This is interpreted in terms of the limiting liquid phase diffusion coefficient and the true liquid phase impedance factor of neptunium-humic acid complexes. 21 figs; 3 tabs; 20 refs

Recent advances in clay mineral-containing nanocomposite hydrogels.

Science.gov (United States)

Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

2015-12-28

Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

Geotechnical properties of Karwar marine clay

Digital Repository Service at National Institute of Oceanography (India)

Bhat, S.T.; Nayak, B.U.; Naik, R.L.

Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

Enrichment and activation of smectite-poor clay

Energy Technology Data Exchange (ETDEWEB)

Sarcevica, Inese; Kostjukovs, Juris; Actint, Andris, E-mail: inese.sarcevicha@gmail.com [Department of Chemistry, University of Latvia, Kr. Valdemara street 48, Riga (Latvia)

2011-06-23

A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

Pure and impure clays and their firing products

International Nuclear Information System (INIS)

Murad, E.; Wagner, U.

1989-01-01

Moessbauer spectroscopy is highly suited for the study of clays whose industrial uses depend on the iron content. Reactions that take place during clay firing can be readily monitored by Moessbauer spectroscopy. Following dehydroxylation of clay minerals, the quadrupole splitting of octahedrally coordinated iron (III) increases abruptly, but reverts to lower values upon the formation of new, better ordered phases at higher temperatures. It is also shown that iron oxides may account for a considerably higher proportion of the total iron content of many clays than is commonly recognized, and their existence must be taken into consideration for a correct interpretation of the Moessbauer spectra of clays. (orig.)

Hydration Phase Diagram of Clay Particles from Molecular Simulations.

Science.gov (United States)

Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

2017-11-07

Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

1.7. Acid decomposition of kaolin clays of Ziddi Deposit. 1.7.1. The hydrochloric acid decomposition of kaolin clays and siallites

International Nuclear Information System (INIS)

Mirsaidov, U.M.; Mirzoev, D.Kh.; Boboev, Kh.E.

2016-01-01

Present article of book is devoted to hydrochloric acid decomposition of kaolin clays and siallites. The chemical composition of kaolin clays and siallites was determined. The influence of temperature, process duration, acid concentration on hydrochloric acid decomposition of kaolin clays and siallites was studied. The optimal conditions of hydrochloric acid decomposition of kaolin clays and siallites were determined.

Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

International Nuclear Information System (INIS)

Ruplis, A.; Mezinskis, G.; Chaghuri, M.

1998-01-01

Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

Feasibility of classification of clay minerals by using PAS

International Nuclear Information System (INIS)

Honda, Y; Yoshida, Y; Akiyama, Y; Nishijima, S

2015-01-01

After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found. (paper)

Clay-Alcohol-Water Dispersions: Anomalous Viscosity Changes Due to Network Formation of Clay Nanosheets Induced by Alcohol Clustering.

Science.gov (United States)

Kimura, Yuji; Haraguchi, Kazutoshi

2017-05-16

Clay-alcohol-water ternary dispersions were compared with alcohol-water binary mixtures in terms of viscosity and optical absorbance. Aqueous clay dispersions to which lower alcohols (ethanol, 1-propanol, 2-propanol, and tert-butanol) were added exhibited significant viscosity anomalies (maxima) when the alcohol content was 30-55 wt %, as well as optical absorbance anomalies (maxima). The maximum viscosity (η max ) depended strongly on the clay content and varied between 300 and 8000 mPa·s, making it remarkably high compared with the viscosity anomalies (2 mPa·s) observed in alcohol-water binary mixtures. The alcohol content at η max decreased as the hydrophobicity of the alcohol increased. The ternary dispersions with viscosity anomalies exhibited thixotropic behaviors. The effects of other hydrophilic solvents (glycols) and other kinds of clays were also clarified. Based on these findings and the average particle size changes, the viscosity anomalies in the ternary dispersions were explained by alcohol-clustering-induced network formation of the clay nanosheets. It was estimated that 0.9, 1.7, and 2.5 H 2 O molecules per alcohol molecule were required to stabilize the ethanol, 2-propanol, and tert-butanol, respectively, in the clay-alcohol-water dispersions.

Chemo-hydro-mechanical behaviour of unsaturated clays

International Nuclear Information System (INIS)

Mokni, N.; Olivella, S.; Alonso, E.E.; Romero, E.

2010-01-01

Document available in extended abstract form only. Understanding of the chemical effects on clays is essential for many problems ranging from pollution studies and waste-containment. Several studies examined the effect of changes in pore fluid composition on the mechanical and hydraulic properties. Volume changes (contraction/ expansion) have been measured on clay specimens upon exposure to salt solutions or permeation with organic liquids. Moreover, it was shown that permeation of clay with brine induces an increase of the shear strength. In addition, several models have been proposed to describe the chemo-mechanical behaviour of saturated clays under saturated conditions. A new chemo-hydro-mechanical model for unsaturated clays is under development. The chemo-mechanical effects are described within an elasto-plastic framework using the concept that chemical effects act on the plastic properties by increasing or decreasing the pre-consolidation stress. The model is based on the distinction within the material of a microstructural and a macro-structural levels. Chemical loading has a significant effect on the microstructure. The negative pressure associated with the capillary water plays its role in the interconnected macro pores. By adopting simple assumptions concerning the coupling between the two levels it is intended to reproduce the features of the behaviour of unsaturated clays when there is a change in pore fluid composition (increase or decrease of concentration). A yield surface which defines the set of yield pre-consolidation stress values, for each associated capillary suction and concentration of pore fluid should be defined. In addition, the behaviour of clays under unsaturated condition and the behaviour at full saturation under chemical loading represent two limiting cases of the framework. Studies on the compatibility of Boom Clay with large amounts of nitrate- bearing bituminized radioactive waste have recently raised a particular interest on the

Establishment of characterizing parameters of clay as a filling material and coverage for repository

International Nuclear Information System (INIS)

Santos, Daisy M.M. dos; Tello, Cledola Cassia Oliveira de

2015-01-01

The multiple barriers of a repository should be able to provide adequate containment of radionuclides during all the previewed time for the operation and institutional control. One of these barriers is the backfill layer, located between the waste packages and other barriers. Furthermore, after shutting the disposal units with concrete, various materials are used to compose the final coverage of the deposition area. The backfill and the cover layer can be composed of clay or clay mixed with cement, with soil or with rocks. The last layer is a vegetation cover. The selection of the best clay should take into consideration some physical-chemical and mechanical properties. Bentonite is a clay with high absorption capacity, and large volume change in moistening and drying processes, being also effective in the contaminant retention. Additionally, it presents unique properties, such as high swelling potential. Some bentonite characterization works have been developed in the Laboratory of Cementation at CDTN/CNEN (LABCIM/CDTN). The sequence of experiments was: granulometric analysis, moisture, compaction test, hydraulic conductivity and cation exchange capacity. Some initial characterization results are presented and discussed. The paper summarizes these previous studies in order to have the basis for creating a protocol for characterization of a bentonite as a reference material. (author)

Establishment of characterizing parameters of clay as a filling material and coverage for repository

Energy Technology Data Exchange (ETDEWEB)

Santos, Daisy M.M. dos; Tello, Cledola Cassia Oliveira de, E-mail: dmms@cdtn.br, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nucelar (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2015-07-01

The multiple barriers of a repository should be able to provide adequate containment of radionuclides during all the previewed time for the operation and institutional control. One of these barriers is the backfill layer, located between the waste packages and other barriers. Furthermore, after shutting the disposal units with concrete, various materials are used to compose the final coverage of the deposition area. The backfill and the cover layer can be composed of clay or clay mixed with cement, with soil or with rocks. The last layer is a vegetation cover. The selection of the best clay should take into consideration some physical-chemical and mechanical properties. Bentonite is a clay with high absorption capacity, and large volume change in moistening and drying processes, being also effective in the contaminant retention. Additionally, it presents unique properties, such as high swelling potential. Some bentonite characterization works have been developed in the Laboratory of Cementation at CDTN/CNEN (LABCIM/CDTN). The sequence of experiments was: granulometric analysis, moisture, compaction test, hydraulic conductivity and cation exchange capacity. Some initial characterization results are presented and discussed. The paper summarizes these previous studies in order to have the basis for creating a protocol for characterization of a bentonite as a reference material. (author)

Chemometric study of Maya Blue from the voltammetry of microparticles approach.

Science.gov (United States)

Doménech, Antonio; Doménech-Carbó, María Teresa; de Agredos Pascual, María Luisa Vazquez

2007-04-01

The use of the voltammetry of microparticles at paraffin-impregnated graphite electrodes allows for the characterization of different types of Maya Blue (MB) used in wall paintings from different archaeological sites of Campeche and YucatAn (Mexico). Using voltammetric signals for electron-transfer processes involving palygorskite-associated indigo and quinone functionalities generated by scratching the graphite surface, voltammograms provide information on the composition and texture of MB samples. Application of hierarchical cluster analysis and other chemometric methods allows us to characterize samples from different archaeological sites and to distinguish between samples proceeding from different chronological periods. Comparison between microscopic, spectroscopic, and electrochemical examination of genuine MB samples and synthetic specimens indicated that the preparation procedure of the pigment evolved in time via successive steps anticipating modern synthetic procedures, namely, hybrid organic-inorganic synthesis, temperature control of chemical reactivity, and template-like synthesis.

Synthetic mullite fabrication from smectite clays

International Nuclear Information System (INIS)

Lima, L.N. de; Kiminami, R.H.G.A.

1988-01-01

The technological importance of mullite is mostly due to its refractory properties. Mullite in native form is very rare, and therefore it may be necessary to produced it by synthetic means. Brazil has a large reserve of smectite clays. In this work the process to produce synthetic mullite from these clays by treatment with aluminum sulphate was studied. X-ray analyses has shown the presence of mullite crystals in treated smectite clays of several colours, sinterized at 1100 0 C. By sintering at 1300 0 C, pure mullite was obtained in some colours. (author) [pt

The Poetics of the Ancestor Songs of the Tz’utujil Maya of Guatemala

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Linda O’Brien-Rothe

2010-04-01

Full Text Available This essay attempts to define the relationship between a song tradition that survives in the Mayan highlands of Guatemala, and 16th century poetic Mayan literature. This song tradition of Santiago Atitlán, Guatemala is slowly disappearing as the socio-cultural context in which it flourished changes. By comparing the poetics of the song texts (including their rhythmic structure, versification, and use of poetic devices such as assonance, alliteration and onomatopoeia to the poetics of the Popol Vuh, a K’iché Maya text probably copied from a manuscript that predates the Spanish invasion, a continuity is discovered that places the song texts squarely within the tradition of Mayan literature and suggests common origins.

Multifaceted role of clay minerals in pharmaceuticals

OpenAIRE

Khurana, Inderpreet Singh; Kaur, Satvinder; Kaur, Harpreet; Khurana, Rajneet Kaur

2015-01-01

The desirable physical and physiochemical properties of clay minerals have led them to play a substantial role in pharmaceutical formulations. Clay minerals like kaolin, smectite and palygorskite-sepiolite are among the world's most valuable industrial minerals and of considerable importance. The elemental features of clay minerals which caused them to be used in pharmaceutical formulations are high specific area, sorption capacity, favorable rheological properties, chemical inertness, swelli...

Aluminium - Cobalt-Pillared Clay for Dye Filtration Membrane

Science.gov (United States)

Darmawan, A.; Widiarsih

2018-04-01

The manufacture of membrane support from cobalt aluminium pillared clay has been conducted. This research was conducted by mixing a clay suspension with pillared solution prepared from the mixture of Co(NO3)2.6H2O and AlCl3.6H2O. The molar ratio between Al and Co was 75:25 and the ratio of [OH-]/[metal] was 2. The clay suspension was stirred for 24 hours at room temperature, filtered and dried. The dried clay was then calcined at 200°C, 300°C and 400°C with a ramp rate of 2°C/min. Aluminium-cobalt-pillared clay was then characterized by XRD and GSA and moulded become a membrane support for subsequent tests on dye filtration. The XRD analysis showed that basal spacing (d 001) value of aluminium cobalt was 19.49 Å, which was higher than the natural clay of 15.08Å however, the basal spacing decreased with increasing calcination temperature. The result of the GSA analysis showed that the pore diameter of the aluminium cobalt pillared clay membrane was almost the same as that of natural clay that were 34.5Å and 34.2Å, respectively. Nevertheless, the pillared clay has a more uniform pore size distribution. The results of methylene blue filtration measurements demonstrated that the membrane filter support could well which shown by a clear filtrate at all concentrations tested. The value of rejection and flux decreased with the increasing concentration of methylene blue. The values of dye rejection and water flux reached 99.89% and 5. 80 x 10-6 kg min-1, respectively but they decreased with increasing concentration of methylene blue. The results of this study indicates that the aluminium-pillared clay cobalt could be used as membrane materials especially for ultrafiltration.

Potent anti-inflammatory activity of sesquiterpene lactones from Neurolaena lobata (L.) R. Br. ex Cass., a Q'eqchi' Maya traditional medicine.

Science.gov (United States)

Walshe-Roussel, Brendan; Choueiri, Christine; Saleem, Ammar; Asim, Muhammd; Caal, Federico; Cal, Victor; Rojas, Marco Otarola; Pesek, Todd; Durst, Tony; Arnason, John Thor

2013-08-01

The widespread use of Neurolaena lobata (L.) R. Br. ex Cass. by Q'eqchi' Maya and indigenous healers throughout the Caribbean for inflammatory conditions prompted the study of the anti-inflammatory activity of this traditional medicine. The objectives of this study were to conduct a detailed ethnobotanical investigation of the uses of N. lobata by the Q'eqchi' Maya of Belize for a variety of inflammatory symptoms and to evaluate the in vitro anti-inflammatory activity of leaf extract and isolated sesquiterpene lactones. The crude 80% EtOH extract of N. lobata leaves administered at 100 μg/mL reduced LPS-stimulated TNF-α production in THP-1 monocytes by 72% relative to the stimulated vehicle control. Isolated sesquiterpene lactones, neurolenins B, C+D, lobatin B and 9α-hydroxy-8β-isovalerianyloxy-calyculatolide were more active (IC50=0.17-2.32 μM) than the positive control parthenolide (IC50=4.79 μM). The results provide a pharmacological and phytochemical basis for the traditional use of this leaf for inflammatory conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bond Behavior of Historical Clay Bricks Strengthened with Steel Reinforced Polymers (SRP)

Science.gov (United States)

Grande, Ernesto; Imbimbo, Maura; Sacco, Elio

2011-01-01

In the strengthening interventions of past and historical masonry constructions, the non-standardized manufacture processes, the ageing and the damage of masonry units, could significantly affect the properties of the surfaces where strengthening materials are applied. This aspect requires particular care in evaluating the performance of externally bonded strengthening layers, especially with reference to the detachment mechanism. The bond response of old masonries could be very different from that occurring in new masonry units which are the ones generally considered in most of the bond tests available in technical literature. The aim of the present paper is the study of the bond behavior of historical clay bricks strengthened with steel reinforced polymers (SRP) materials. In particular, the results of an experimental study concerning new manufactured clay bricks and old bricks extracted from different historical masonry buildings are presented. The obtained results, particularly in terms of bond resistance, detachment mechanism and strain distributions, are discussed for the purpose of analyzing the peculiarities of the historical bricks in comparison with new manufactured ones. Some considerations on the efficacy of the theoretical formulations of the recent Italian code are also carried out. PMID:28880008

clay nanocomposite by solution intercalation technique

Indian Academy of Sciences (India)

Polymer–clay nanocomposites of commercial polystyrene (PS) and clay laponite were prepared via solution intercalation technique. Laponite was modified suitably with the well known cationic surfactant cetyltrimethyl ammonium bromide by ion-exchange reaction to render laponite miscible with hydrophobic PS.

Impact-Induced Clay Mineral Formation and Distribution on Mars

Science.gov (United States)

Rivera-Valentin, E. G.; Craig, P. I.

2015-01-01

Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

Polyethersulfone/clay membranes and its water permeability

International Nuclear Information System (INIS)

Cavalho, Thamyres Cardoso de; Medeiros, Vanessa da Nobrega; Araujo, Edcleide Maria de; Lira, Helio Lucena; Leite, Amanda Melissa Damiao

2017-01-01

Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By Xray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure surface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow. (author)

Influence of clay organic modifier on morphology and performance of poly(ε-caprolactone/clay nanocomposites

Directory of Open Access Journals (Sweden)

Nikolić Marija S.

2015-01-01

Full Text Available Two series of poly(e-caprolactone nanocomposites with different organo-modified clays (1 to 8 wt% were prepared by the solution casting method. Organoclays with polar (Cloisite®C30B and nonpolar (Cloisite®C15A organic modifier and with different miscibility with poly(e-caprolactone matrix, were chosen. Exfoliated and/or intercalated nanocomposite’s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite®C30B, which had better miscibility with poly(e-caprolactone matrix. Differences in spherulites’ sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young’s modulus with experimentally obtained ones in tensile tests.[Projekat Ministarstva nauke Republike Srbije, br. 172062

Characterization of archaeological ceramics from the north western lowland Maya Area, using the technique of neutron activation analysis

International Nuclear Information System (INIS)

Lopez R, M. C.; Tenorio, D.; Jimenez R, M.; Terreros, E.; Ochoa, L.

2008-01-01

It is a study on 50 samples of ceramics from various archaeological sites of the north western lowland Maya Area. This study was performed by neutron activation analysis of 19 chemical elements and the treatments relevant statistical data. Significant differences were found among the pieces that led to group them into five major groups, the difference is the site of their manufacture and therefore in the raw materials used for this. (Author)

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Raman P. Singh

2010-01-01

Full Text Available This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

International Nuclear Information System (INIS)

Singh, R.P.; Zunjarrao, S.C.; Pandey, G.; Khait, M.; Korach, C.S.

2010-01-01

This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Studies on Tagged Clay Migration Due to Water Movement

International Nuclear Information System (INIS)

Scharpenseel, H.W.; Kerpen, W.

1967-01-01

55 Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B t -development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of 55 Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for 55 Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

A method for generating stochastic 3D tree models with Python in Autodesk Maya

Directory of Open Access Journals (Sweden)

Nemanja Stojanović

2016-12-01

Full Text Available This paper introduces a method for generating 3D tree models using stochastic L-systems with stochastic parameters and Perlin noise. L-system is the most popular method for plant modeling and Perlin noise is extensively used for generating high detailed textures. Our approach is probabilistic. L-systems with a random choice of parameters can represent observed objects quite well and they are used for modeling and generating realistic plants. Textures and normal maps are generated with combinations of Perlin noises what make these trees completely unique. Script for generating these trees, textures and normal maps is written with Python/PyMEL/NumPy in Autodesk Maya.

clay nanocomposites

Indian Academy of Sciences (India)

The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

α-Pinene conversion by modified-kaolinitic clay

International Nuclear Information System (INIS)

Volzone, C.; Masini, O.; Comelli, N.A.; Grzona, L.M.; Ponzi, E.N.; Ponzi, M.I.

2005-01-01

The isomerization of α-pinene using natural kaolinitic clay before and after different treatments was studied in this work. The kaolinite is a clay material constituted by phyllosilicate 1:1 layer (one sheet of tetrahedral silicon and one sheet of octahedral alumina). The clay was treated at different times using 6.0 N solution of sulfuric acid previous heating to 500 or 700 K. The materials were characterized by X-ray diffraction, by chemical analyses and acidity measurements. The catalytic reactions were carried out at 373 K in a reactor batch with condenser and stirrer. Samples were taken at regular intervals, and reactants and products were quantitatively analyzed with a gas chromatograph after separation of the individual compounds. Conversions of alpha pinene between 67 and 94%, and selectivities in camphene and in limonene of 65 and 23%, respectively, were obtained with the clay treated at different conditions. The structural and textural changes of the clay by the treatments influenced on catalytic reactions

{alpha}-Pinene conversion by modified-kaolinitic clay

Energy Technology Data Exchange (ETDEWEB)

Volzone, C. [CETMIC-Centro de Tecnologia de Recursos Minerales y Ceramica-(CONICET-CIC), C.C. 49, Cno. Centenario y 506 (1897) M.B. Gonnet, Prov., Buenos Aires (Argentina)]. E-mail: volzcris@netverk.com.ar; Masini, O. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Comelli, N.A. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Grzona, L.M. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Ponzi, E.N. [CINDECA (CONICET-UNLP) calle 47 No. 257 (1900) La Plata, Prov., Buenos Aires (Argentina); Ponzi, M.I. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina)

2005-10-15

The isomerization of {alpha}-pinene using natural kaolinitic clay before and after different treatments was studied in this work. The kaolinite is a clay material constituted by phyllosilicate 1:1 layer (one sheet of tetrahedral silicon and one sheet of octahedral alumina). The clay was treated at different times using 6.0 N solution of sulfuric acid previous heating to 500 or 700 K. The materials were characterized by X-ray diffraction, by chemical analyses and acidity measurements. The catalytic reactions were carried out at 373 K in a reactor batch with condenser and stirrer. Samples were taken at regular intervals, and reactants and products were quantitatively analyzed with a gas chromatograph after separation of the individual compounds. Conversions of alpha pinene between 67 and 94%, and selectivities in camphene and in limonene of 65 and 23%, respectively, were obtained with the clay treated at different conditions. The structural and textural changes of the clay by the treatments influenced on catalytic reactions.

Active containment systems incorporating modified pillared clays

International Nuclear Information System (INIS)

Lundie, P.; McLeod, N.

1997-01-01

The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation

Controlling harmful algae blooms using aluminum-modified clay.

Science.gov (United States)

Liu, Yang; Cao, Xihua; Yu, Zhiming; Song, Xiuxian; Qiu, Lixia

2016-02-15

The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tensile mechanical response of polyethylene – clay nanocomposites.

Directory of Open Access Journals (Sweden)

2007-03-01

Full Text Available In this work we report on the microstructural and the mechanical characteristics of high density polyethylene (HDPE-clay nanocomposites, with particular attention to the creep behaviour. The samples were prepared through melt compounding, using two high-density polyethylenes with different melt flow rate (MFR, two different organo-modified clays, and changing the relative amount of a polyethylene grafted with maleic anhydride (PEgMA compatibilizer. The intercalation process is more effective as the matrix melt viscosity decreases (higher MFR, while the clay interlamellar spacing increases as the compatibilizer amount increases. The relative stiffness of the nanocomposites increases with the addition of clay, with a limited enhancement of the relative yield stress. The better intercalation obtained by the addition of the compatibilizer is not accompanied by a concurrent improvement of the tensile mechanical properties. The creep resistance is enhanced by the introduction of clay, with an appreciable dependence on both the polyethylene and the clay type.

Buenos Aires y salta en rito cívico: la revolución y las fiestas mayas

OpenAIRE

Juan Carlos Garavaglia

2002-01-01

El articulo es una relectura de los acontecimientos de los primeros años postrevolucionarios en el Plata. Centrado en las fiestas mayas, las analiza como uno de los elementos claves en la constitución de nuevas formas de imaginar la experiencia política iniciada en 1810. La comparación entre Buenos Aires y Salta, permite mostrar algunas de diferencias en las maneras de vivir estas fiestas "revolucionarias"; esas diferencias reflejan por supuesto realidades sociales y culturales...

Crecimiento del pulpo Octopus maya (Mollusca: Cephalopoda de la costa de Yucatán, México: un análisis de largo plazo

Directory of Open Access Journals (Sweden)

Marta Rocío Nepita Villanueva

2001-03-01

Full Text Available Los parámetros de crecimiento del pulpo (Octopus maya de las costas de Yucatán (México fueron estimados en siete años comprendidos entre 1983-1987, 1989 y 1992. A tales efectos se realizó un análisis de frecuencia de tallas de 19 251 pulpos muestreados de la captura comercial, con un intervalo de longitud de manto comprendido entre 50 y 240 mm. Se usaron los métodos indirectos ELEFAN, PROJMAT y SLCA. La incertidumbre de las estimaciones inherente a cada método y derivada del diseño de muestreo fue analizada con la técnica jackknife. Los parámetros de crecimiento L y K se unificaron a efectos comparativos mediante el índice phi prima (. El método ELEFAN resultó ser el más adecuado para estimar los parámetros de crecimiento de O. maya, brindando valores en el rango de aquellos previamente reportados en la literatura, mientras que PROJMAT y SLCA mostraron problemas en la convergencia de los parámetros, y tendieron a subestimarlos. Las estimaciones mediante jackknife detectaron poca variabilidad intermensual en pero gran variabilidad interanual. Los estimadores de precisión de la técnica jackknife, error porcentual y coeficiente de variación porcentual, no difirieron significativamente entre métodos. Las estimaciones de derivadas del ELEFAN variaron entre 4.19 y 5.23, coincidiendo con aquellas reportadas en la literatura (entre 4.25 y 4.91, mientras que PROJMAT y SLCA aportaron valores significativamente menores. Los resultados de dicho métodos condicen además con aspectos de la biología de la especie (e.g., corta longevidad. Sugerimos utilizar el ELEFAN conjuntamente con jackknife para estimar los parámetros de crecimiento de Octopus maya.Growth of the octopus (Octopus maya off Yucatan (Mexico was estimated from a long-term study (seven years by the length-based methods ELEFAN, PROJMAT and SLCA. Some 19 251 octopuses with a range of mantle length between 50 and 240 mm were sampled from commercial landings in 1983 - 1987

Study of radionuclide migration in clay formations

International Nuclear Information System (INIS)

Antonioli, F.; Bocola, W.

1985-01-01

This paper reports the studies on the migration of Cs, Sr and I in clay formations, which are presently considered for the geological disposal of radioactive wastes. The distribution and diffusion coefficients were evaluated by means of experimental techniques and computer procedures, which are presented in this report. The natural clays tested in the laboratory experiments were sampled from the most representative italian basins and from the zone of Mol (Belgium). In addition tests were performed on monomineral clays artificially remade in edometer. The experimental results are in accordance with data found in the literature and show the existence of a good correlation between the observed migration properties and the granulometric and mineralogic characteristics of the natural clays

Influence of chemical treatment of clay to obtain polypropylene nanocomposites

International Nuclear Information System (INIS)

Rosa, Jeferson L.S.; Marques, Maria F.V.

2009-01-01

Commercial clay was chemically treated to prepare a Ziegler-Natta catalyst containing MgCl 2 and clay for the synthesis of polypropylene nanocomposites by in situ polymerization. The performance of this catalyst and materials obtained in propylene polymerization was compared with a reference catalyst (without clay) and with another, whose composition presents the same clay but without prior chemical treatment. Techniques like differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and melt flow index (MFI) measurements were performed. There was a marked reduction in catalytic activity of clay catalysts in comparison with the reference one, and a slight reduction in melting temperature of the polymers produced from first ones. The melt flow index of polymers obtained with treated clay were notably higher than those synthesized with the untreated clay, so the treated clay caused treated the production of PP's with lower molar mass. The clays showed an increase of spacing and irregular stacking of the lamellas, especially if chemically treated. (author)

Restricciones culturales en la alimentación de Mayas Chortis y Ladinos del Oriente de Guatemala

OpenAIRE

López García, Julián

2011-01-01

Partiendo de las bases metodológicas del análisis simbólico en antropología, la presente tesis pretende desentrañar alguno de los aspectos social y cognitivamente significativos de la alimentación y todo lo asociado a ella en una zona del oriente de Guatemala, jocotan (chiquimula) donde conviven indígenas mayas chortis y ladinos (mestizos). En la tesis que presento he destacado la importancia de la comida en la zona como medio para conocer y atribuir identidades. Así, posibilita la formación ...

Milpa y capitalismo: opciones para los campesinos mayas yucatecos contemporáneos

Directory of Open Access Journals (Sweden)

Manuel Martín Castillo

2016-07-01

Full Text Available La mayoría de los mayas yucatecos contemporáneos vive en la pobreza. El eje de su economía y cultura es la agricultura de milpa, que los jóvenes no encuentran atractiva como opción económica. La teoría económica convencional explica la pobreza por la escasez de capital, el uso de tecnologías obsoletas y la baja productividad. Aunque se concibe como un sistema productivo arcaico, la milpa tiene características para explorar opciones de vinculación entre las economías campesina y capitalista, para mejorar las condiciones de vida de los campesinos y contribuir al desarrollo de su cultura en el actual contexto de globalización económica.

Studies on Tagged Clay Migration Due to Water Movement

Energy Technology Data Exchange (ETDEWEB)

Scharpenseel, H. W. [Institut fuer Bodenkunde der Universitaet Bonn, Federal Republic of Germany (Germany); Kerpen, W. [Arbeitsgruppe, Institut fuer Landwirtschaft der KFA Juelich, Bonn, Federal Republic of Germany (Germany)

1967-11-15

{sup 55}Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B{sub t}-development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of {sup 55}Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for {sup 55}Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

Geological Investigations on Boulder-Clay of E. Groningen

NARCIS (Netherlands)

Gijzel, van P.; Overweel, C.J.; Veenstra, H.J.

1959-01-01

In this article the results of a study on boulder-clay in the neighbourhood of Winschoten (N.E. Netherlands) are communicated (Chapter I). The underlying sediments of the boulder-clay in this area consist of fine preglacial sands and black clay. In the nuclei of the many drumlins a strongly

Nanoporous polymer--clay hybrid membranes for gas separation.

Science.gov (United States)

Defontaine, Guillaume; Barichard, Anne; Letaief, Sadok; Feng, Chaoyang; Matsuura, Takeshi; Detellier, Christian

2010-03-15

Nanohybrid organo-inorgano clay mineral-polydimethylsiloxane (PDMS) membranes were prepared by the reaction of pure and/or modified natural clay minerals (Sepiolite and montmorillonite) with PDMS in hexane, followed by evaporation of the solvent at 70 degrees C. The membranes were characterized by means of XRD, SEM, ATD-TG and solid state (29)Si magic angle spinning (MAS) and cross-polarization (CP) CP/MAS NMR. The morphology of the membranes depends on the content loading of clay mineral. For low content, the membrane composition is homogeneous, with well dispersed nanoparticles of clay into the polymer matrix, whereas for higher clay content, the membranes are constituted also of a mixture of well dispersed nanoparticles into the polymer, but in the presence of agglomerations of small clay particles. Quantitative (29)Si MAS NMR demonstrated a strong correlation between the clay content of the membrane and the average length of the PDMS chain, indicating that the nanohybrid material is made of clay particles covalently linked to the PDMS structure. This is particularly the case for Sepiolite with has a high density of Q(2) silanol sites. The separation performances of the prepared membranes were tested for CO(2)/CH(4) and O(2)/N(2) mixtures. The observed separation factors showed an increase of the selectivity in the case of CO(2)/CH(4) in comparison with membranes made from PDMS alone under the same conditions. 2009 Elsevier Inc. All rights reserved.

Polyurethane/organo clay nano composite materials via in-situ polymerization

International Nuclear Information System (INIS)

Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

2005-01-01

Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

Development of polymer nanocomposites with regional bentonite clay

International Nuclear Information System (INIS)

Araujo, Edcleide M.; Leite, Amanda M.D.; Paz, Rene A. da; Medeiros, Keila M. de; Melo, Tomas J.A.; Barbosa, Josiane D.V.; Barbosa, Renata

2011-01-01

nanocomposites with regional bentonite clay were prepared by melt intercalation technique. The clays were studied without modification and modified with four quaternary ammonium salts. It was evidenced by X-ray diffraction that salts were incorporated into the clay structure thus confirming its organophilization. The nanocomposites were evaluated by means of thermal mechanic and flammability tests where presented properties significantly improved their pure polymers. The process of biodegradation of obtained bio nanocomposites was accelerated by the presence of clay. The produced membranes from nanocomposites have potential in the oil-water separation. (author)

Clays causing adhesion with tool surfaces during mechanical tunnel driving

Science.gov (United States)

Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

2009-04-01

During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

Corrosion behaviour of carbon steel in the Tournemire clay

International Nuclear Information System (INIS)

Foct, F.; Dridi, W.; Cabrera, J.; Savoye, S.

2004-01-01

Carbon steels are possible materials for the fabrication of nuclear waste containers for long term geological disposal in argillaceous environments. Experimental studies of the corrosion behaviour of such materials has been conducted in various conditions. Concerning the numerous laboratory experiments, these conditions (water and clay mixture or compacted clay) mainly concern the bentonite clay that would be used for the engineered barrier. On the opposite, only few in-situ experiments has been conducted directly in the local clay of the repository site (such as Boom clay, etc.). In order to better estimate the corrosion behaviour of carbon steels in natural clay site conditions, an experimental study has been conducted jointly by EDF and IRSN in the argillaceous French site of Tournemire. In this study, A42 carbon steel specimens have been exposed in 3 different zones of the Tournemire clay formation. The first type of environmental conditions concerns a zone where the clay has not been affected by the excavation (EDZ) of the main tunnel neither by the main fracture zone of the clay formation. The second and third ones are located in the EDZ of the tunnel. In the second zone, an additional aerated water flows from the tunnel, whereas it does not in the third place. Some carbon steel specimens have been extracted after several years of exposure to these conditions. The average corrosion rate has been measured by the weight loss technique and the pitting corrosion depth has been evaluated under an optical microscope. Corrosion products have also been characterised by scanning electron microscopy and X-ray diffraction technique. Results are then discussed regarding the surrounding environmental conditions. Calculations of the oxygen transport from the tunnel through the clay and of the clay re-saturation can explain, in a first approach, the corrosion behaviour of the carbon steel in the different tested zones. (authors)

Thermally modified bentonite clay for copper removal

International Nuclear Information System (INIS)

Bertagnolli, C.; Kleinübing, S.J.; Silva, M.G.C.

2011-01-01

Bentonite clay coming from Pernambuco was thermally modified in order to increase its affinity and capacity in the copper removal in porous bed. The application of this procedure is justified by the low cost of clay, their abundance and affinity for various metal ions. Thermally treatment modifies the clay adsorption properties enables its use in porous bed system, with the increase in surface area and mechanical strength. The material was characterized by x-ray diffraction, thermogravimetric analysis and N_2 physisorption. Then tests were carried out for adsorption of copper in various experimental conditions and evaluated the mass transfer zone, useful and total adsorbed removal amounts and total copper removal percentage. The results showed that the clay treated at higher temperature showed higher copper removal. (author)

Performance of Kaolin Clay on the Concrete Pavement