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40 resultados encontrados para: TEMA: Composición química
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1.
Artículo
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Pharmacological effects and toxicity of Costus pulverulentus C. Presl (Costaceae) 
Alonso Castro, Ángel Josabad (autor) ; Zapata Morales, Juan Ramón (autor) ; González Chávez, Marco Martin (autor) ; Carranza Álvarez, Candy (autora) ; Hernández Benavides, Diego Manuel (autor) ; Hernández Morales, Alejandro (autor) ;
Contenido en: Journal of Ethnopharmacology Vol. 180 (March 2016), p. 124–130 ISSN: 0378-8741
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Resumen en: Inglés |
Resumen en inglés

Ethnopharmacological relevance: Costus pulverulentus C. Presl (Costaceae), a species endemic to Mexico, is used for the empirical treatment of cancer, pain, and inflammation. Aim of the study: The objective of this study was to evaluate the toxicity, as well as the cytotoxic, antinociceptive, anti-inflammatory and sedative effects of an ethanol extract from Costus pulverulentus stem (CPE). Materials and methods: The chemical characterization of CPE was performed by Gas chromatography–mass spectrometry (GC–MS). The toxicity of CPE was evaluated using the comet assay (10–1000 µg/ml during 5 h) and the acute toxicity test (500–5000 mg/kg p.o. and i.p. during 14 days). The cytotoxic effect of CPE (1–250 µg/ml) on human cancer cells was evaluated using the MTT assay. The antinociceptive effects of CPE (50–200 mg/kg p.o.) were evaluated using thermal-induced nociception tests (hot plate and tail flick) and the chemical-induced nociceptive tests (acetic acid and formalin). The sedative activity of CPE (50–200 mg/kg p.o.) was evaluated using the ketamine-induced sleeping time test.

Results: CPE showed the presence of compounds such as campesterol, stigmasterol β-sitosterol, vanillicacid, among others. In the comet assay, CPE at 200 µg/ml or higher concentrations induced DNA damage. In the acute toxicity test, the LD 50 estimated for CPE was > 5000 mg/kg p.o. or i.p. CEP showed moderate cytotoxic effects on prostate carcinoma cells PC-3 cells (IC 50=179+23.2 µg/ml). In the chemical-induced nociception models, CPE (100 and 200 mg/kg p.o.) showed antinociceptive effects with similar activity to 100 mg/kg naproxen. In the thermal-induced nociception tests, CPE tested at 200 mg/kg showed moderate antinociceptive effects by 28% (hot plate test) and by 25% (tail fl ick test). In the ketamine-induced sleeping time test, CPE showed no sedative effects. Conclusions: C. pulverulents exerts moderate cytotoxic effects in human cancer cells, moderate anti-inflammatory and antinociceptive effects. C. pulverulentus induces antinociceptive effects without inducing sedation.


2.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Climate forcings on vegetation of the southeastern Yucatán Peninsula (Mexico) during the middle to late Holocene
Aragón Moreno, Alejandro Antonio ; Islebe, Gerald A. (coaut.) ; Roy, Priyadarsi D. (coaut.) ; Torrescano Valle, Nuria (coaut.) ; Mueller, Andreas D. (coaut.) ;
Contenido en: Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 495 (April 2018), p. 214-226 ISSN: 0031-0182
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Resumen en: Inglés |
Resumen en inglés

Climate and vegetation history from the Yucatán Peninsula, southeastern Mexico, are inferred from a mangrove sediment core deposited between the middle and late Holocene (~5600–1700 cal yr B.P.) in the Rio Hondo Delta. Fossil pollen and concentrations of Ca and Fe and Ca/Fe ratio in sediments are used to record changes in vegetation and climate. Palaeoecological and palaeoclimatic interpretations obtained from pollen abundances and associations and Fe/Ca ratio coincide with dynamics of major global forcings of climate change like ITCZ, ENSO and global cooling. Mesic conditions enabled tropical forest expansion during the middle Holocene (~5600–3650 cal yr B.P.), although there were periodic dry episodes at ~5200 cal yr B.P. and at ~4300 cal yr B.P. that caused disturbance and enabled herbaceous vegetation to expand. Changes in sedi- mentation and a gradual change from semi-evergreen to dry tropical forest occurred at ~3650 cal yr B.P., with increasing ENSO activity and southward migration of the ITCZ during transition of the middle to late Holocene. The driest period and lowest forest cover occurred between ~2600 and 2000 cal yr B.P. Data show that over the last two millennia, influence of the ENSO on southeastern Mexico is stronger compared to other proxy-records of climate variability from the Caribbean region.


3.
Artículo
Características agronómicas y químicas del género Buddleia en los Altos de Chiapas
Camacho Morfín, Deneb ; Nahed Toral, José (coaut.) ; Ochoa Gaona, Susana (coaut.) ; Morfín Loyden, L. (coaut.) ; Soto Pinto, Lorena (coaut.) (1958-) ; Jiménez Ferrer, Guillermo (coaut.) ;
Clasificación: AR/635.93396 / C3
Contenido en: Investigación Multidisciplinaria (1996), p. 16-19
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
ECO010012870 (Disponible)
Disponibles para prestamo: 1

4.
Artículo
*En hemeroteca, SIBE-San Cristóbal, SIBE-Villahermosa
Contenido nutricional de inflorescencias de palmas en la sierra del Estado de Tabasco
Centurión Hidalgo, Dora ; Alor Chávez, Maricela de Jesús (coaut.) ; Espinosa Moreno, Judith (coaut.) ; Gómez García, E. (coaut.) ;
Contenido en: Universidad y Ciencia Vol. 25, no. 3 (diciembre 2009), p. 193-199 ISSN: 0186-2979
Bibliotecas: San Cristóbal , Villahermosa
Cerrar
SIBE San Cristóbal
49262-20 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Villahermosa
49262-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal, SIBE-Villahermosa
PDF
Resumen en: Español | Inglés |
Resumen en español

En la Región de la Sierra del estado de Tabasco aún se presentan rasgos de la cultura alimentaria tradicional al consumir las inflorescencias de palmas silvestres (Astrocaryum mexicanum, Chamaedorea alternans y Chamaedorea tepejilote). La parte comestible de las inflorescencias se deshidrataron para realizar los análisis (químico proximal, minerales y fibra dietaria). Se encontraron diferencias significativas (p < 0.05) en los resultados del análisis proximal y del contenido de minerales presentándose el mayor porcentaje de proteína cruda (25.39 %) y de extracto etéreo (2.26 %) en las inflorescencias de C. alternans y en C. tepejilote los de cenizas (17.25 %) y fibra cruda (12.16 %). Con respecto a los minerales, el hierro estuvo presente en menor cantidad (13.9 mg (100g)-1) en la inflorescencia de A. mexicanum mientras que en C. alternans y C. tepejilote los contenidos fueron de alrededor de 25 mg (100g)-1. El mayor valor de calcio se presentó en las inflorescencias de C. alternans y C. tepejilote con 2458 y 2479 mg (100g)-1), respectivamente. Por otro lado, se encontró que los mayores valores de magnesio, potasio, sodio, Fibra Dietaria Total y Fibra Dietaria Insoluble fueron para la inflorescencia de A. mexicanum.

Resumen en inglés

The inhabitants of the Tabasco mountains still retain aspects of their traditional food culture by eating the inflorescences of the wild palm tree (Astrocaryum mexicanum, Chamaedorea alternans and Chamaedorea tepejilote). The edible parts of the inflorescences were dehydrated for analyses (proximal chemical, mineral content and dietary fiber). Significant di erences were recorded (p < 0.05) for the results obtained for the proximal analysis and the mineral content, with the greatest percentage of crude protein (25.39 %) and of ethereal extract (2.26 %) in the C. alternans inflorescences, and of ash (17.25 %) and total fiber (12.16 %) in C. tepejilote. Regarding the minerals, the A. mexicanum inflorescences presented the lowest amount of Iron (13.9 mg (100g)-1), whereas C. alternans and C. tepejilote recorded approximately 25 mg (100g)-1. The greatest value for Calcium was recorded in the C. alternans and C. tepejilote inflorescences with 2458 and 2479 mg (100g)-1 respectively. The A. mexicanum inflorescences presented the greatest values of Magnesium, Potassium, Sodium, Total Dietary Fiber and Insoluble Dietary Fiber.


5.
Libro
Marine geochemistry / Roy Chester
Chester, Roy (1936-) ;
Oxford : Blackwell Science , 2000
Clasificación: 551.4601 / C4
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030000818 (Disponible)
Disponibles para prestamo: 1

6.
- Capítulo de libro con arbitraje
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Characterization of Scaptotrigona mexicana Pot-Pollen from Veracruz, Mexico
Contreras Oliva, Adriana (autora) ; Pérez Sato, Juan Antonio (autor) ; Gómez Merino, Fernando Carlos (autor) ; López Garay, Luz Anel (autora) ; Villanueva Gutiérrez, Rogel (autor) ; Crosby Galván, María Magdalena (autora) ; Trejo Téllez, Libia Iris (autora) ;
Disponible en línea
Contenido en: Pot-pollen in stingless bee melittology / Patricia Vit, Silvia R.M. Pedro, David W. Roubik, editors Cham, Switzerland, German : Springer International Publishing AG, 2018 p. 325-337 ISBN:978-3-319-61838-8 :: 978-3-319-61839-5 (eBook)
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7.
Artículo
PDF
Resumen en: Inglés |
Resumen en inglés

This study was aimed at evaluating thein vitroeffect of the edible mushroom (EM) Pleurotus eryngiiagainst the eggs and larvae (L3) of Haemonchus contortus. The evaluation included acetone (AE) and hydroalcoholic (HA) extracts of the following strains: ECS-1138, ECS-1156, ECS-1255, ECS-1258, ECS-1261, ECS-1282, and ECS-1292. The HA extract of the ECS-1255 strain showed thehighest effect on mortality rates of L3 (18.83%) at 20 μg/mL. After subjecting this HA extract to a normal phase chromatography column, five fractions were obtained; fraction F5 (100% MeOH) was the most effective against eggs, with hatching inhibition percentages of 88.77 and 91.87% at 20 and 40 mg/mL, respectively. Gas chromatography-mass spectrometry (GC-MS) subjected this fraction to an acetylation reaction to determine the content of the secondary metabolites. The GC-MSanalysis showed that the F5 fraction was composed of trehalose CAS: 6138-23-4, polyols (L-iditol CAS: 488-45-9, galactitol CAS:608-66-2, D-mannitol CAS: 69-65-8, D-glucitol CAS: 50-70-4, and myoinositol CAS: 87-89-8), adipic acid CAS: 124-04-9, stearic acid CAS: 57-11-4, squalene CAS: 111-02-4, and β-sitosterol CAS: 83-46-5.


8.
- Artículo con arbitraje
*En hemeroteca, SIBE-Tapachula
Mandibular gland secretion of Melipona beecheii: chemistry and behavior
Cruz López, Leopoldo Caridad (coaut.) ; Malo Rivera, Edi Álvaro (coaut.) ; Morgan E., Dacid (coaut.) ; Rincon, Manuel (coaut.) ; Guzmán Díaz, Miguel Ángel (coaut.) ; Rojas, Julio C. (coaut.) ;
Contenido en: Journal of Chemical Ecology Vol. 31, no. 7 (July de 2005), p. 1621-1632 ISSN: 0098-0331
Bibliotecas: Tapachula
Cerrar
SIBE Tapachula
46482-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Tapachula
Resumen en: Inglés |
Resumen en inglés

The mandibular gland secretion of Melipona beecheii contains a rich mixture of terpenoid and oxygenated compounds and unsaturated and saturated hydrocarbons. However, it differs markedly from the 11 other Brazilian species examined in previous studies, both by the absence of 2-heptanol and the presence of rose oxides. The most abundant compound was geranyl hexanoate, whereas the most volatile compounds were cis- and trans-rose oxide and geraniol. The complete blend and five individual components found in the gland secretion were tested by electroantennography (EAG) and behavioral assays. The complete mandibular gland extract and geraniol elicited the strongest EAG responses, whereas these and farnesyl acetate induced the strongest attack response from workers. The role of the rose oxides remains to be elucidated, as they do not appear to play a major role as an alarm pheromone of this species.


9.
Libro
Chemistry and geothermanl systems / A. J. Ellis; W. A. J. Mahon
Ellis, A. J. ; Mahon, W. A. J. ;
New York : Academic , 1977
Clasificación: 553.79 / E4
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030003192 (Disponible)
Disponibles para prestamo: 1

10.
Libro
Principles and applications of geochemistry: a comprehensive textbook for geology students / Gunter Faure
Faure, Gunter ;
New Jersey : Prentice Hall , c1998
Clasificación: 551.9 / F3
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030008397 (Disponible)
Disponibles para prestamo: 1
Índice | Resumen en: Inglés |
Resumen en inglés

Designed to show readers how to use chemical principles in solving geological problems, this book emphasizes a quantitative approach to problem solving and demonstrates how chemical principles control geologic processes in atomic and large-scale environments. The book starts with basic principles and emphasizes quantitative methods of problem-solving. It uses the principles of isotope geology to enhance the understanding of appropriate geochemical subject areas. The book also examines the geochemical processes that affect the chemical composition of surface water and that determine its quality for human consumption. For anyone interested in Geochemistry or Geology.

Índice

Preface
Part I
Planet Earth in the Solar System
1
What Is Geochemistry?
1.1 Early History
1.2 Geochemistry in the U.S.S.R.
1.3 V. M. Goldschmidt
1.4 Modern Geochemistry
References
2
In the Beginning
2.1 The Big Bang
2.2 Stellar Evolution
2.3 Nucleosynthesis
2.4 Summary
Problems
References
3
The Solar System
3.1 Origin of the Solar System
3.2 Origin of the Earthlike Planets
3.3 Satellites of the Outer Planets
3.4 Pictures of Our Solar System
3.5 Summary
References
4
Chemical Differentiation of the Earth
4.1 Internal Structure of the Earth
4.2 The Continental Crust: Major Elements
4.3 Differentiation of Igneous and Sedimentary Rocks
4.4 Differentiation of the Hydrosphere
4.5 Summary
Problems
References
Part II
Principles of Inorganic Geochemistry
5
The Electronic Structure of Atoms
5.1 The Atom of Thomson and Rutherford
5.2 Bohr’s Theory of the Hydrogen Atom
5.3 Emission of X-rays
5.4 Schrödinger’s Model of the Atom
5.5 The Aufbau Principle
5.6 Summary
Problems
References
6
The Periodic Table and Atomic Weights
6.1 Mendeleev’s Periodic Table
6.2 The Modern Periodic Table
6.3 Basic Principles of Atomic Physics
6.4 Atomic Weights
6.5 Summary
Problems
References
7
Chemical Bonds , Ionic Radii, and Crystals
7.1 Electron Donors Versus Acceptors
7.2 Measures of Metallic Character
7.3 Bonding in Molecules
7.4 Ionic Crystals
7.5 Ionic Radii
7.6 Summary
Problems
References
8
Ionic Substitution in Crystals
8.1 Goldschmidt’s Rules of Substitution
8.2 Camouflage, Capture, and Admission
8.3 Coupled Substitution: Key to the Feldspars
8.4 Distribution Coefficients and Geothermometers
8.5 Geochemical Classification of the Elements
8.6 Summary

Part III
Aqueous Geochemistry and the Stability Of Minerals
9
Acids and Bases
9.1 Chemical Reactions and Equilibria
9.2 The Law of Mass Action
9.3 Dissociation of Weak Acids and Bases
9.4 Solubility of Sparingly Soluble Bases
9.5 pH Control of Dissociation Equilibria
9.6 Solubility of Amorphous Silica
9.7 Summary Problems References
10
Salts and Their Ions
10.1 Solubility of Salts
10.2 Hydrolysis
10.3 Activities and Concentrations
10.4 Solubility of Calcium Carbonate
10.5 Chemical Weathering
10.6 Transformation of Potassium Feldspar to Kaolinite
10.7 Summary
Problems
References
11
Thermodynamics
11.1 Definitions
11.2 The First Law
11.3 Enthalpy
11.4 Heats of Reaction
11.5 Heat Capacity
11.6 The Second Law
11.7 Gibbs Free Energy
11.8 Derivation of the Law of Mass Action
11.9 Fugacity and Activity
11.10 The van’t Hoff Equation
11.11 Solubility of Amorphous Silica Between 0 and 100 °C
11.12 Summary
Problems
References
12
Mineral Stability Diagrams
12.1 Chemical Weathering of Feldspars
12.2 Formation of Zeolites
12.3 Magnesium Silicates
12.4 Solubility Diagrams
12.5 Fugacity Diagrams
12.6 Summary
Problems
References
13
Clay Minerals
Crystal Structure
Classification and Chemical Composition
Gibbs Free Energies of Formation
Stability Diagrams
Colloidal Suspensions and Ion Exchange
Dating of Clay Minerals
Summary
Problems
References
14
Oxidation-Reduction Reactions
Balancing Equations of Oxidation-Reduction Reactions
The Electromotive Series
The Emf of Electrochemical Cells
Stability Limits of Water in Terms of Eh and pH
Stability of Iron Compounds
Summary
Problems
References
15
Rates of Geochemical Processes
15.1 Rates of Chemical Reactions
15.2 Transport of Matter: Advection
15.3 Transport of Matter: Diffusion
15.4 Growth of Concretions During Diagenesis
15.5 Growth of Monomineralic Layers

15.6 Summary
Problems
References
Part IV
Isotope Geochemistry and Mixing
16
Isotopic Geochronometers
16.1 Decay Modes
16.2 Law of Radioactivity
16.3 Methods of Dating
16.4 Cosmogenic Radionuclides
16.5 Summary
Problems
References
17
Isotope Fractionation
17.1 Principles of Isotope Fractionation
17.2 Mathematical Relations
17.3 Isotope Fractionation in the Hydrosphere
17.4 Oxygen Isotope Composition of Calcite
17.5 Oxygen and Hydrogen in Clay Minerals
17.6 Groundwater and Geothermal Brines
17.7 Isotope Fractionation of Carbon
17.8 Isotope Compositions of Strontium in Carbonate Rocks
17.9 Isotope Fractionation of Sulfur
17.10 Summary
Problems
References
18
Mixing and Dilution
18.1 Binary Mixtures
18.2 Dilution
18.3 Evaporative Concentration
18.4 Ternary Mixtures
18.5 Isotopic Mixtures of One Element
18.6 Isotopic Mixtures of Two Elements
18.7 Summary
Problems
References
Part V
Applications of Geochemistry To the Solution of Global Problems
19
Consequences of Chemical Weathering
19.1 Changes in Chemical Composition of Rocks
19.2 Normative Mineral Composition of Weathering Products
19.3 Susceptibility of Minerals to Weathering
19.4 Formation of Placer Deposits
19.5 Provenance Determination by Isotopic Dating
19.6 Formation of Soils
19.7 Geomicrobiology
19.8 Food Production and Population Growth
19.9 Summary
Problems
References
20
Chemical Composition of Surface Water
20.1 Chemical Analysis of Water in Streams
20.2 Chemical Composition of Streams
20.3 Chemical Composition of Meteoric Precipitation
20.4 Normative Minerals from Water Compositions
20.5 Evaporative Concentration
20.6 Water Quality
20.7 Summary
Problems
References
21
Chemical Weathering of Mineral Deposits
21.1 Metallic Mineral Deposits
21.2 Oxidation of Iron Sulfides and the Role of Bacteria
21.3 Eh-pH Diagram for Copper Minerals

21.4 Supergene Enrichment of Fe-Cu Sulfide Deposits
21.5 Replacement of Pyrite by Chalcocite —
21.6 Oxidation of Ore Minerals of Other Metals
21.7 Geochemical Exploration
21.8 Production and Consumption of Mineral Resources
21.9 Summary
Problems
References
22
Geochemical Cycles
22.1 The Principle of Mass Balance
22.2 Mass Balance for Major Elements in the Ocean
22.3 Mass Balance for Trace Elements in the Ocean
22.4 The Cycles of C-H-O-N
22.5 The Sulfur Cycle
22.6 Summary
Problems
References
23
Chemistry of the Atmosphere
23.1 Structure and Composition
23.2 Ultraviolet Radiation
23.3 Ozone in the Stratosphere
23.4 Ozone Hole over Antarctica
23.5 Infrared Radiation and the Greenhouse Effect
23.6 Prediction of the Future Global Climate
23.7 Summary
Problems
References
24
Environmental Geochemistry: Disposal of Radioactive Waste
24.1 The Big Picture
24.2 High-Level Nuclear Waste Disposal
24.3 Geological Disposal of Radioactive Waste
24.4 Geochemistry of Plutonium
24.5 Eh-pH Diagrams of Neptunium and Plutonium
24.6 Analog Studies: The Natural Reactors at Oklo, Gabon
24.7 Reactor Accidents: Chernobyl, Ukraine
24.8 Summary
Problems
References
25
Effect of Environmental Lead on Human Health
25.1 Isotope Composition of Environmental Lead
25.2 Lead in the Environment
25.3 Lead in Plants
25.4 Lead Poisoning of Cows and Horses
25.5 Human Bones and Tissues
25.6 Lead in the Bones of Ancient Peoples
25.7 Summary
Problems
References
Appendix A
Compilations of Geochemical Data
Appendix B
Standard Gibbs Free Energies (G°f ) and Standard Enthalpies of Formation (H°f )
Author Index
Subject Index