Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Más filtros

Medicinas Complementárias
Métodos Terapéuticos y Terapias MTCI
Tipo del documento
Intervalo de año de publicación
1.
Zhongguo Zhong Yao Za Zhi ; 49(4): 868-883, 2024 Feb.
Artículo en Chino | MEDLINE | ID: mdl-38621894

RESUMEN

Scorpio is a valuable Chinese animal medicine commonly used in clinical practice in China. It is the main drug in the treatment of liver wind internal movement caused by various reasons throughout the history of traditional Chinese medicine(TCM), with the effects of relieving wind and spasm, dredging collaterals, relieving pain, and eliminating toxin and mass. Scorpio is poisonous and often used as medicine after processing. There are records of its processing as early as the Song Dynasty. Afterward, there were more than 15 processing methods, including frying with vinegar, neat processing, and stir-frying. After processing, the fishy smell could be removed to correct the taste, and the toxicity could be reduced, which was beneficial to clinical application. At present, the main reported components in Scorpio are protein polypeptides, alkaloids, and lipids, with many pharmacological effects, such as anti-cancer, anti-coagulation, anti-thrombosis, anti-atherosclerosis, and anti-bacteria. In this study, the historical evolution of processing, chemical constituents, and pharmacological action of Scorpio were discussed in order to provide references for the related research on Scorpio.


Asunto(s)
Alcaloides , Medicamentos Herbarios Chinos , Animales , Evolución Química , Medicamentos Herbarios Chinos/farmacología , Medicina Tradicional China , Alcaloides/farmacología
2.
Zhongguo Zhong Yao Za Zhi ; 48(12): 3269-3280, 2023 Jun.
Artículo en Chino | MEDLINE | ID: mdl-37382011

RESUMEN

Bombyx Batryticatus is a precious traditional Chinese animal drug commonly used in clinical practice in China, which has the effects of extinguishing wind, stopping convulsions, dispelling wind, relieving pain, resolving phlegm, and dissipating mass. The processing of Bombyx Batryticatus has a long history. As early as in the Liu Song period of the Southern and Northern Dynasties, there was a record of the processing of Bombyx Batryticatus with rice swill. In addition to the processing with bran, honey bran, and ginger juice, which are still used today, there are also processing methods such as rendering, flour processing, wine processing, salt processing, oil processing, charcoal, and red dates processing in ancient times. After processing, the fishy smell of Bombyx Batryticatus can be removed, and avoid nausea and vomiting caused by the direct taking. Furthermore, processing can also facilitate the removal of surface hairs and toxicity reduction, making the medicinal material crispy and easy to crush. Previous studies have shown that the main chemical constituents of Bombyx Batryticatus include protein polypeptides, sterols, and flavonoids, with anticonvulsant, anticoagulation, antithrombotic, anti-cancer, hypnotic, hypoglycemic, and other pharmacological effects. This paper reviewed the processing historical evolution, chemical constituents, and pharmacological effects of Bombyx Batryticatus to lay a foundation for the research on the processing mechanism, quality control, and active core substances of Bombyx Batryticatus.


Asunto(s)
Bombyx , Animales , China , Evolución Química , Flavonoides , Frutas
3.
Zhongguo Zhong Yao Za Zhi ; 47(21): 5806-5816, 2022 Nov.
Artículo en Chino | MEDLINE | ID: mdl-36471998

RESUMEN

As a traditional animal drug, Hirudo is slightly toxic and has the effects of breaking blood stasis, dredging meridians, expelling stasis, and resolving mass. It has a long history of processing, and the early boiling records can be traced back to the Han Dynasty. More than ten processing methods such as frying, roasting, and lime processing appeared later. After processing, Hirudo is deodorized and modified in taste and becomes crispy, which is conducive to crushing and clinical application. At present, the reported components in Hirudo mainly include protein polypeptides, pteridines, and lipids, which have anti-coagulant, anti-thrombotic, anti-atherosclerotic, anti-tumor, and other pharmacological effects. This study reviewed the processing history evolution, chemical consti-tuents, and pharmacological effects of Hirudo to provide a reference for the related research on Hirudo.


Asunto(s)
Medicamentos Herbarios Chinos , Sanguijuelas , Trombosis , Animales , Medicamentos Herbarios Chinos/farmacología , Evolución Química , Restricción Física
4.
Crit Rev Eukaryot Gene Expr ; 31(3): 1-3, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34369710

RESUMEN

The reductionist strategy, adopted by physics and chemistry, which was based on the effort to reduce the concepts necessary for the statement of scientific explanations to a minimum, was attractive to those who worked in the biomedical field. On the other hand, the vitalistic point of view opposed mechanism, believing that there were processes in living organisms that do not obey the laws of physics and chemistry. Finally, the holistic approach is focused on the evidence that the organized whole is almost always much more than the sum of its parts, and have led to direct attention to emerging qualities in a highly organized system which is a living being.


Asunto(s)
Biología/ética , Evolución Química , Genética Médica/ética , Salud Holística , Vida , Vitalismo , Animales , Humanos , Filosofía Médica
5.
Zhongguo Zhong Yao Za Zhi ; 45(17): 4163-4182, 2020 Sep.
Artículo en Chino | MEDLINE | ID: mdl-33164402

RESUMEN

Polygonati Rhizoma(PR), listed as a top-grade medicine, was recorded first in the Mingyi Bielu written by TAO Hongjing. It is a good medicine through the ages to tonify Qi and nourish Yin, strengthen spleen and kidney. PR has a long history of processing and has a variety of processing methods and technologies. Steaming and stewing are the main processing methods. There are many different excipients used in processing PR, such as wine, honey, black beans, and multiple excipients. At present, there are three plant varieties of PR recorded in Chinese Pharmacopoeia, including Polygonatum sibiricum, P. kingianum and P. cyrtonema, collectively called medicinal PR. Medicinal PR has a wide range of chemical components, mainly including polysaccharides, steroidal saponins, flavonoids, phenylpropanoids and alkaloids etc. It also has a wide range of pharmacological effects, such as anti-oxidation, anti-osteoporosis and anti-tumor effects. In this paper, we review the historical evolution, chemical components, pharmacological effects, and the effects of processing on ingredients and pharmacological effects of PR. We also analyze the limitations of the current research on PR, and put forward the prospects on the scientific connotation of processing, quality improvement, process innovation and new product development of PR for further researches.


Asunto(s)
Polygonatum , Vino , Evolución Química , Polisacáridos , Rizoma
6.
Chem Rev ; 120(11): 4898-4918, 2020 06 10.
Artículo en Inglés | MEDLINE | ID: mdl-31804075

RESUMEN

The use of high hydrostatic pressure to investigate structure-function relationships in biomacromolecules in solution provides precise information about conformational changes and variations of the interactions between these macromolecules and the solvent, as well as the volume changes associated with their activity. The complementary use of osmotic pressure reveals quantitatively the extent and direction of the water exchanges between the macromolecules and the solvent and the number of water molecules involved in these exchanges. In this review, the chemistry of ribozymes and the influence of pressure is described. In the case of the hairpin ribozyme, pressure slowed down the self-cleavage reaction on the basis that the formation of the transition state involves a positive ΔV⧧ of activation and the release of 78 ± 4 water molecules. The self-cleaving activity of the hammerhead ribozyme is also slowed down by pressure on the basis of kinetic parameters and ΔVs comparable to those of the hairpin ribozymes. However, it appears that the solution of the hammerhead ribozyme used in this study contains two populations of molecules which differ by the values of these parameters. The results obtained in the case of small self-cleaving ribozymes containing adenine bulges are consistent with the hypothesis that these small RNAs that bind amino acids or peptides could have appeared in prebiotic chemistry under extreme conditions in deep-sea vents or hydrothermal surface sites.


Asunto(s)
Presión Hidrostática , Presión Osmótica , ARN Catalítico/química , Aminoácidos/química , Aminoácidos/metabolismo , Evolución Química , Cinética , Concentración Osmolar , Péptidos/química , Péptidos/metabolismo , Conformación Proteica , ARN Catalítico/metabolismo
7.
Orig Life Evol Biosph ; 48(2): 213-222, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29705890

RESUMEN

The Ser-His dipeptide is the shortest active peptide. This dipeptide not only hydrolyzes proteins and DNA but also catalyzes the formation of peptides and phosphodiester bonds. As a potential candidate for the prototype of modern hydrolase, Ser-His has attracted increasing attention. To explore if Ser-His could be obtained efficiently in the prebiotic condition, we investigated the reactions of N-DIPP-Ser with His or other amino acids in an aqueous system. We observed that N-DIPP-Ser incubated with His can form Ser-His more efficiently than with other amino acids. A synergistic effect involving the two side chains of Ser and His is presumed to be the critical factor for the selectivity of this specific peptide formation.


Asunto(s)
Dipéptidos/síntesis química , Origen de la Vida , Fósforo/química , Catálisis , Evolución Química , Hidrolasas/química
8.
Zhongguo Zhen Jiu ; 37(3): 325-330, 2017 Mar 12.
Artículo en Chino | MEDLINE | ID: mdl-29231444

RESUMEN

With human placed in the whole nature, by following the biologic evolution path, the property of channel structure for "imprinting template" in meridian and zang-fu was explored with supramolecular chemistry. In the history of biologic evolution, each molecule in "molecule society" gradually developed into various highly-ordered supramolecular bodies based on self-identification, self-assembly, self-organization, self-replicating of"imprinting template", and thereby the original biochemical system was established, and finally evolved into human. In the forming process of supramolecular bodies, the channel structure of"imprinting template" in guest supramolecular bodies would be kept by host supramolecular bodies, and communicate with the outside to exchange materials, energy, information, otherwise life phenomenon could not continue, for which it was the chemical nature of biolo-gical supramolecular bodies for body to develop meridian. Therefore, the human was a gigantic and complicated supramolecules body in biological nature, and possessed the supramolecules "imprinting template" at each stage of evolution, for which the meridians were formed. When meridians converged, acupoints appeared; when acupointsconverged, zang-fu appeared. With the promotion of the blood from heart, according to"imprinting template", the guest supramolecular bodies and host meridian produced qi-analysis, which was the qi-phenomenon of guest in meridian. It presented as zang-fu image of physiology and pathology as well as action regularities of medication and acupuncture tolerance, by which current various meridian viewpoints could be explained and propose the hypothesis of meridian supramolecular bodies. The meridian and its phenomenon was decide by its "imprinting template" of supramolecular bodies and self-reaction regularities, which abided through the living nature. This was the substance for meridian biology.


Asunto(s)
Evolución Biológica , Evolución Química , Meridianos , Puntos de Acupuntura , Terapia por Acupuntura , Humanos
9.
Sci Rep ; 7(1): 636, 2017 04 04.
Artículo en Inglés | MEDLINE | ID: mdl-28377577

RESUMEN

The occurrence of extraterrestrial organic compounds is a key for understanding prebiotic organic synthesis in the universe. In particular, amino acids have been studied in carbonaceous meteorites for almost 50 years. Here we report ten new amino acids identified in the Murchison meteorite, including a new family of nine hydroxy amino acids. The discovery of mostly C3 and C4 structural isomers of hydroxy amino acids provides insight into the mechanisms of extraterrestrial synthesis of organic compounds. A complementary experiment suggests that these compounds could be produced from aldehydes and ammonia on the meteorite parent body. This study indicates that the meteoritic amino acids could be synthesized by mechanisms in addition to the Strecker reaction, which has been proposed to be the main synthetic pathway to produce amino acids.


Asunto(s)
Aminoácidos/análisis , Aminoácidos/química , Meteoroides , Aldehídos/química , Amoníaco/química , Evolución Química , Estructura Molecular , Soluciones
10.
Clin Liver Dis ; 21(1): 197-214, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-27842772

RESUMEN

In this article, we review the past applications of in vitro models in identifying human hepatotoxins and then focus on the use of multiscale experimental models in drug development, including the use of zebrafish and human cell-based, 3-dimensional, microfluidic systems of liver functions as key components in applying Quantitative Systems Pharmacology (QSP). We have implemented QSP as a platform to improve the rate of success in the process of drug discovery and development of therapeutics.


Asunto(s)
Enfermedad Hepática Inducida por Sustancias y Drogas/prevención & control , Diseño de Fármacos , Evaluación Preclínica de Medicamentos/métodos , Hígado/efectos de los fármacos , Animales , Descubrimiento de Drogas , Evolución Química , Humanos , Mamíferos , Modelos Animales , Valor Predictivo de las Pruebas , Medición de Riesgo
11.
Orig Life Evol Biosph ; 45(1-2): 207-18, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25773584

RESUMEN

The ubiquity of phosphorus (P) in modern biochemistry suggests that P may have participated in prebiotic chemistry prior to the emergence of life. Of the major biogenic elements, phosphorus alone lacks a substantial volatile phase and its ultimate source therefore had to have been a mineral. However, as most native P minerals are chemically un-reactive within the temperature-pressure-pH regimes of contemporary life, it begs the question as to whether the most primitive early living systems on earth had access to a more chemically reactive P-mineral inventory. The meteoritic mineral schreibersite has been proposed as an important source of reactive P on the early earth. The chemistry of schreibersite as a P source is summarized and reviewed here. Recent work has also shown that reduced oxidation state P compounds were present on the early earth; these compounds lend credence to the relevance of schreibersite as a prebiotic mineral. Ultimately, schreibersite will oxidize to phosphate, but several high-energy P intermediates may have provided the reactive material necessary for incorporating P into prebiotic molecules.


Asunto(s)
Evolución Química , Minerales/química , Fósforo/química , Agua/química , Planeta Tierra , Meteoroides , Origen de la Vida , Oxidación-Reducción
12.
Proc Natl Acad Sci U S A ; 110(25): 10089-94, 2013 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-23733935

RESUMEN

It has been hypothesized that before the emergence of modern DNA-RNA-protein life, biology evolved from an "RNA world." However, synthesizing RNA and other organophosphates under plausible early Earth conditions has proved difficult, with the incorporation of phosphorus (P) causing a particular problem because phosphate, where most environmental P resides, is relatively insoluble and unreactive. Recently, it has been proposed that during the Hadean-Archean heavy bombardment by extraterrestrial impactors, meteorites would have provided reactive P in the form of the iron-nickel phosphide mineral schreibersite. This reacts in water, releasing soluble and reactive reduced P species, such as phosphite, that could then be readily incorporated into prebiotic molecules. Here, we report the occurrence of phosphite in early Archean marine carbonates at levels indicating that this was an abundant dissolved species in the ocean before 3.5 Ga. Additionally, we show that schreibersite readily reacts with an aqueous solution of glycerol to generate phosphite and the membrane biomolecule glycerol-phosphate under mild thermal conditions, with this synthesis using a mineral source of P. Phosphite derived from schreibersite was, hence, a plausible reagent in the prebiotic synthesis of phosphorylated biomolecules and was also present on the early Earth in quantities large enough to have affected the redox state of P in the ocean. Phosphorylated biomolecules like RNA may, thus, have first formed from the reaction of reduced P species with the prebiotic organic milieu on the early Earth.


Asunto(s)
Evolución Química , Océanos y Mares , Origen de la Vida , Fósforo/química , ARN/química , Carbonatos/química , Evolución Planetaria , Exobiología , Óxido Ferrosoférrico/química , Geología , Meteoroides , Oxidación-Reducción , Fosforilación
13.
Mar Pollut Bull ; 66(1-2): 164-75, 2013 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-23174304

RESUMEN

The fluorescence EEM technique, PARAFAC modeling, and hydrocarbon composition were used to characterize oil components and to examine the chemical evolution and degradation pathways of Macondo crude oil under controlled laboratory conditions. Three major fluorescent oil components were identified, with Ex/Em maxima at 226/328, 262/315, and 244/366 nm, respectively. An average degradation half-life of ∼20 d was determined for the oil components based on fluorescence EEM and hydrocarbon composition measurements, showing a dynamic chemical evolution and transformation of the oil during degradation. Dispersants appeared to change the chemical characteristics of oil, to shift the fluorescence EEM spectra, and to enhance the degradation of low-molecular-weight hydrocarbons. Photochemical degradation played a dominant role in the transformation of oil components, likely an effective degradation pathway of oil in the water column. Results from laboratory experiments should facilitate the interpretation of field-data and provide insights for understanding the fate and transport of oil components in the Gulf of Mexico.


Asunto(s)
Evolución Química , Contaminación por Petróleo , Petróleo/análisis , Contaminantes Químicos del Agua/química , Monitoreo del Ambiente/métodos , Fluorescencia , Laboratorios , México , Modelos Químicos , Espectrometría de Fluorescencia , Contaminantes Químicos del Agua/análisis
14.
J Mol Evol ; 69(5): 481-96, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19911220

RESUMEN

Energised by the protonmotive force and with the intervention of inorganic catalysts, at base Life reacts hydrogen from a variety of sources with atmospheric carbon dioxide. It seems inescapable that life emerged to fulfil the same role (i.e., to hydrogenate CO(2)) on the early Earth, thus outcompeting the slow geochemical reduction to methane. Life would have done so where hydrothermal hydrogen interfaced a carbonic ocean through inorganic precipitate membranes. Thus we argue that the first carbon-fixing reaction was the molybdenum-dependent, proton-translocating formate hydrogenlyase system described by Andrews et al. (Microbiology 143:3633-3647, 1997), but driven in reverse. Alkaline on the inside and acidic and carbonic on the outside - a submarine chambered hydrothermal mound built above an alkaline hydrothermal spring of long duration - offered just the conditions for such a reverse reaction imposed by the ambient protonmotive force. Assisted by the same inorganic catalysts and potential energy stores that were to evolve into the active centres of enzymes supplied variously from ocean or hydrothermal system, the formate reaction enabled the rest of the acetyl coenzyme-A pathway to be followed exergonically, first to acetate, then separately to methane. Thus the two prokaryotic domains both emerged within the hydrothermal mound-the acetogens were the forerunners of the Bacteria and the methanogens were the forerunners of the Archaea.


Asunto(s)
Crecimiento Quimioautotrófico , Evolución Química , Calor , Origen de la Vida , Fuerza Protón-Motriz , Agua de Mar/química , Oligoelementos/metabolismo , Acetatos/metabolismo , Archaea/metabolismo , Bacterias/metabolismo , Cobre/metabolismo , Metabolismo Energético , Hierro/metabolismo , Metano/metabolismo , Modelos Biológicos , Molibdeno/metabolismo , Níquel/metabolismo , Ósmosis , Selenio/metabolismo , Azufre/metabolismo
15.
Astrobiology ; 9(2): 165-71, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19371159

RESUMEN

Interaction of ribonucleotides--namely, 5'-AMP, 5'-GMP, 5'-CMP, and 5'-UMP--with acidic, neutral, and basic alumina has been studied. Purine nucleotides showed higher adsorption on alumina in comparison with pyrimidine nucleotides under acidic conditions. Adsorption data obtained followed Langmuir adsorption isotherm, and X(m) and K(L) values were calculated. On the basis of infrared spectral studies of ribonucleotides, alumina, and ribonucleotide-alumina adducts, we propose that the nitrogen base and phosphate moiety of the ribonucleotides interact with the positive charge surface of alumina. Results of the present study may indicate the importance of alumina in concentrating organic molecules from dilute aqueous solutions in primeval seas in the course of chemical evolution on Earth.


Asunto(s)
Óxido de Aluminio/química , Evolución Química , Ribonucleótidos/química , Adsorción , Carbono/análisis , Hidrógeno/análisis , Concentración de Iones de Hidrógeno , Nitrógeno/análisis , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Suspensiones , Agua/química
16.
J Inorg Biochem ; 102(5-6): 1104-11, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18329104

RESUMEN

The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal-ions. The absence of uridilate derivative polymerization on adenine containing templates has been the main issue preventing an efficient template-directed RNA polymerization. We report here the investigation of template-directed RNA polymerization in the eutectic phase in water-ice. In particular, it was found that activated uridilate monomers in the presence of metal-ion catalysts could efficiently elongate RNA hairpins whose 5'-overhangs served as the templating sequence. The same applies for every other pyrimidine and purine nucleobase. Moreover, the initial elongation rates were always higher in the presence of a template complementary to the nucleotide than in systems without proper base-pairing opportunities. These results suggest that a template-directed RNA polymerization catalyzed by metal-ions could be carried out under eutectic phase in water-ice conditions.


Asunto(s)
Polímeros/química , ARN/química , Adenina/química , Citosina/química , Evolución Química , Guanina/química , Hielo , Moldes Genéticos , Uracilo/química , Agua
17.
Chem Commun (Camb) ; (22): 2344-6, 2006 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-16733574

RESUMEN

Anoxic irradiation of a type IIICD iron meteorite known to contain the phosphide mineral schreibersite (Fe,Ni)3P in the presence of ethanol/water affords the reactive oxyacid H-phosphinic acid (H3PO2) as the dominant phosphorus product.


Asunto(s)
Meteoroides , Ácidos Fosfínicos/química , Ácidos Fosfínicos/síntesis química , Fósforo/química , Etanol/química , Evolución Química , Oxidación-Reducción , Solubilidad , Agua/química
18.
Chem Soc Rev ; 34(8): 691-701, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16186898

RESUMEN

In this tutorial review we consider the role of phosphorus and its compounds within the context of chemical evolution in galaxies. Following an interdisciplinary approach we first discuss the position of P among the main biogenic elements by considering its relevance in most essential biochemical functions as well as its peculiar chemistry under different physicochemical conditions. Then we review the phosphorus distribution in different cosmic sites, such as terrestrial planets, interplanetary dust particles, cometary dust, planetary atmospheres and the interstellar medium (ISM). In this way we realize that this element is both scarce and ubiquitous in the universe. These features can be related to the complex nucleosynthesis of P nuclide in the cores of massive stars under explosive conditions favouring a wide distribution of this element through the ISM, where it would be ready to react with other available atoms. A general tendency towards more oxidized phosphorus compounds is clearly appreciated as chemical evolution proceeds from circumstellar and ISM materials to protoplanetary and planetary condensed matter phases. To conclude we discuss some possible routes allowing for the incorporation of phosphorus compounds of prebiotic interest during the earlier stages of solar system formation.


Asunto(s)
Evolución Química , Fósforo/química , Polvo Cósmico , Cristalografía por Rayos X , Modelos Moleculares , Compuestos Organometálicos/química , Compuestos Organofosforados/química , Compuestos de Fósforo/química , Temperatura
19.
Acta amaz ; 34(3): 375-386, jul.-set. 2004. ilus, mapas, tab, graf
Artículo en Inglés | LILACS | ID: lil-393982

RESUMEN

This paper carried out a chemical investigation of archaeological ceramic artifacts found in archaeological sites with Black Earth (ABE) in the Lower Amazon Region at Cachoeira-Porteira, State of Pará, Brazil. The ceramic artifacts, mostly of daily use, belong to Konduri culture (from 900 to 400 years BP). They are constituted of SiO2, Al2O3, Fe2O3, Na2O and P2O5; SiO2 and Al2O3 together add up to 80 percent and indicate influence of acid rocks, transformed into clay minerals basically kaolinite. The relative high contents of P2O5 (2.37 percent in average) come out as (Al,Fe)-phosphate, an uncommon fact in primitive red ceramics, but found in some roman and egyptian archaeological sites. The contents of the trace elements are similar or below the Earth's crust average. This chemical composition (except P2O5) detaches saprolite material derived acid igneous rocks or sedimentary ones as the main raw material of the ceramics. The contents of K, Na and Ca represent the feldspars and rock fragments possibly introduced into saprolitic groundmass, indicated by mineralogical studies. The presence of cauixi and cariapé as well as quartz sand was confirmed by optical microscope, SEM analyses and by the high silica contents of ceramic fragments. Phosphorus was possibly incorporated into groundmass during cooking of foods, and ABE soil profile formation developed on yellow Latosols. The raw materials and its tempers (cauixi, or cariapé, feldspar, crushed rocks, old ceramic artifacts and quartz fragments) are found close to the sites and therefore and certainly came from them.


Asunto(s)
Fósforo , Suelo , Química , Evolución Química
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(6): 1359-65, 2004 May.
Artículo en Inglés | MEDLINE | ID: mdl-15134735

RESUMEN

Electron spin resonance (ESR) was used to date the formation and most recent recrystallization of three types of gypsum samples (massive, bedded and fracture filling gypsum) from the Sakarya Formation at Eskisehir in the middle of Turkey. The ESR spectra had the signals of Fe3+ and Mn2+ in addition to those of the G1 and G2 sensitive centers (g = 2.002 and 2.008) to artificial gamma-irradiation. ESR intensities of G1 and G2 were enhanced by gamma-ray irradiation to give equivalent doses DE) for each sample. The ESR ages derived from the annual doses of 238U, 232Th and 40K contents of the samples determined by thermal neutron activation analysis (TNAA) were between 43 +/- 18 ka (massive gypsum) and 1100 +/- 466 ka (bedded gypsum) as minimal and maximal values. The ages fall into the upper Miocene-Pliocene Epoch of the geological time scale, which agreed with the stratigraphy.


Asunto(s)
Sulfato de Calcio/análisis , Espectroscopía de Resonancia por Spin del Electrón , Cristalización , Evolución Química , Rayos gamma , Hierro/análisis , Manganeso/análisis , Análisis de Activación de Neutrones , Radioisótopos de Potasio/análisis , Dosis de Radiación , Radioisótopos , Torio/análisis , Turquía , Uranio/análisis
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA