1,751,132 research outputs found
JPC-J. Planar Chromatogr.-Mod. TLC
No full textWhile in situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures, the conventional stationary phase, such as silica gel, used for TLC/FTIR analysis, has strong absorption in IR region and thus brings about severe interference in the obtained FTIR spectra of the separated samples. In this work, we propose to use lanthanum fluoride fine particles as a new stationary phase of a TLC plate. The average size of LaF3 particles is around 100 nm. FTIR spectrum of the LaF3 particles has no interfering absorption. Preliminary TLC experiments show that mixtures of rhodamine B and methylene blue mixture can be successfully separated by this new TLC plate using LaF3 fine particles as a stationary phase. Methylene blue and rhodamine B from separated spot can be clearly detected by using in situ FTIR spectra.While in situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures, the conventional stationary phase, such as silica gel, used for TLC/FTIR analysis, has strong absorption in IR region and thus brings about severe interference in the obtained FTIR spectra of the separated samples. In this work, we propose to use lanthanum fluoride fine particles as a new stationary phase of a TLC plate. The average size of LaF3 particles is around 100 nm. FTIR spectrum of the LaF3 particles has no interfering absorption. Preliminary TLC experiments show that mixtures of rhodamine B and methylene blue mixture can be successfully separated by this new TLC plate using LaF3 fine particles as a stationary phase. Methylene blue and rhodamine B from separated spot can be clearly detected by using in situ FTIR spectra
THE SUGAR MARKET IN COLOMBIA AND ITS INTERACTIONS WITH THE USA MARKET
No full textEn este artículo se propone un modelo de equilibrio parcial para entender el comportamiento del mercado del azúcar en Colombia y sus interacciones comerciales con la economía norteamericana. Se evalúan los posibles efectos de un TLC con Estados Unidos sobre el mercado, al igual que la incidencia de otros factores internos y externos. Se prueba que el impacto de un TLC entre Colombia y Estados Unidos depende del balancede dos fuerzas contrapuestas: el incremento en la proporción de la cuota que corresponde a las exportaciones colombianas, y la baja progresiva que se ha venido presentando en la cuota total de la economía norteamericana.In this paper it is proposed a partial equilibrium model for the sugar market of Colombia to understand its trade relations with the North-American economy. The possible effects of a Free Trade Agreement and of other internal and external factors are examined modelling the functioning of the North-American sugar market. It is proved that the impact of a FTA between Colombia and the USA depend of two forces: the impact of the increase in the proportion of the quota affecting the Colombian exports, and the effectof progressive decreases in the value of the total North-American quota.Sugar market, international trade, freetrade agreement, import quotas / Mercado del azúcar, comercio internacional,tratado de libre comercio,cuotas de importación.
Impacto del TLC en Bogotá-Cundinamarca. Servicios de software
No full textEste informe sobre el impacto del TLC en Bogotá-Cundinamarca Servicios de software incluye el rezago frente a la globalización, el impacto del TLC en la economía regional y el TLC y la cadena de servicios de software.Gestión del conocimientoCompetitivida
Validating and developing TLC-based fingerprinting for Curcuma longa L.
No full textContext: Curcuma longa (turmeric) is extensively cultivated as spices and herbal medicines in tropical and sub-tropical countries. Geographical origin is known to significantly determine the quality of the herbs used and, consequently, the safety and efficacy of their products.
Aims: To validate and develop TLC-fingerprint combined with
chemometrics to differentiate C. longa collected from various origins.
Methods: Thin Layer Chromatography (TLC) was employed together with chemometric methods, i.e., Principal Component Analysis (PCA) and Cluster Analysis (CA), to evaluate the quality of C. longa rhizomes collected from nine origins in Indonesia.
Results: Chloroform, dichloromethane, and ethanol (64:64:1) were a suitable mobile phase for C. longa. The method used met the requirements for a stable and precise TLC system. As analyzed by the chemometric techniques, the TLC-fingerprints could discriminate C. longa from various origins. The PCA score plot of the first two principal components (PCs) and CA clearly distinguished two clusters of simples.
Conclusions: When combined with PCA and CA, TLC-fingerprinting can discern the rhizomes of C. longa sourced from various locations. TLCfingerprints that are analyzed with chemometrics can be used as an alternative marker-oriented method for evaluating the quality of C. longa
Modification of an office scanner for the determination of aflatoxins after TLC separation
No full textS.109-112A computer-driven office scanner has been modified to enable measurement of the fluorescence of aflatoxins on thin-layer chromatography (TLC) plates. The main modifications were substitution of the Light tube with a black light tube and inclusion of a filter, The strategy behind this modification, and its problems, are discussed. The modified scanner can be used to determine aflatoxins at low nanogram levels, which, when used in combination with an appropriate TLC method, enables monitoring of the compounds in food and feed at the levels stipulated in European legislation.14Nr.
Language and Imagination: Evolutionary explorations
No full textThis article provides a functional analysis of the conditions for language to emerge, and analyzes its rolein imagination. It starts with some initial reflections on imagination and its evolutionary beginnings in relation to the role of working memory and tool use by chimpanzees and humans up to modernity. It then presents an analysis of what it takes to develop language, and how language gives rise to higher orders of imagination. An important theme in the discussion is which of the changes in the development leading to language may have been gradual and which changes must reflect a discontinuity. It concludeswith a paradoxical property of imagination: One part of our mind is able to imagine and create systems that another part of our mind is unable to deal with. It shows how this tension manifests itself in the notion of an impossible language, but crucially also in conceptions of human society at large
Dinâmicas de cooperação entre ímpares
No full textDeconstruction of the discourse in the area of International Cooperation, with the main focus in relations with Africa. Desconstrução do discurso na área da Cooperação Internacional, com enfoque principal nas relações com a África
Impacto del TLC en Bogotá-Cundinamarca La cadena de industrias gráficas
No full textGestión del conocimientoEste informe sobre el impacto del TLC en Bogotá-Cundinamarca La cadena de cuero-calzado incluye el rezago frente a la globalización, el impacto del TLC en la economía regional y el TLC y la cadena de industrias gráficas.Competitivida
The First Female University Student: Anna Maria van Schurman (1636)
No full textDigitale publicatie en printing on deman
Impacto del TLC en Bogotá-Cundinamarca La cadena de cuero-calzado
No full textGestión del conocimientoEste informe sobre el impacto del TLC en Bogotá-Cundinamarca La cadena de cuero-calzado incluye el rezago frente a la globalización, el impacto del TLC en la economía regional y el TLC y la cadena de cuero y calzado.Competitivida
- …
