Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 114
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Sustain Sci ; 17(5): 2013-2029, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35340343

RESUMEN

Forests are key components of European multifunctional landscapes and supply numerous forest ecosystem services (FES) fundamental to human well-being. The sustainable provision of FES has the potential to provide responses to major societal challenges, such as climate change, biodiversity loss, or rural development. To identify suitable strategies for the future sustenance of FES, we performed a solution scanning exercise with a group of transdisciplinary forest and FES experts from different European regions. We identified and prioritized fifteen major challenges hindering the balanced provision of multiple FES and identified a series of potential solutions to tackle each of them. The most prominent challenges referred to the increased frequency and impacts of extreme weather events and the normative mindset regarding forest management. The respective solutions pointed to the promotion of forest resilience via climate-smart forestry and mainstreaming FES-oriented management through a threefold strategy focusing on education, awareness raising, and networking. In a subsequent survey, most solutions were assessed as highly effective, transferable, monitorable, and with potential for being economically efficient. The implementation of the solutions could have synergistic effects when applying the notion of leverage points. Seven emerging pathways towards the sustainable supply of FES have been identified. These pathways build on each other and are organized based on their potential for transformation: (1) shifting forest management paradigms towards pluralistic ecosystem valuation; (2) using integrated landscape approaches; (3) increasing forest resilience; (4) coordinating actions between forest-related actors; (5) increasing participation in forest planning and management; (6) continuous, open, and transparent knowledge integration; and (7) using incentive-based instruments to support regulating and cultural FES. These pathways can contribute to the implementation of the new EU Forestry Strategy to support the balanced supply of multiple FES. Supplementary Information: The online version contains supplementary material available at 10.1007/s11625-022-01111-4.

2.
Anal Chim Acta ; 675(1): 16-23, 2010 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-20708110

RESUMEN

The development of near infrared (NIR) sensors has to go through different steps of testing. Once a prototype is ready to be used, it is necessary to evaluate and optimize the experimental conditions and the data collection, in terms of accuracy, repeatability, reproducibility and speed. This paper studies the effects of controllable experimental factors on the quality of the spectral response, to determine the influence of each instrumental parameter and to improve the predictions obtained from the collected data. The AComDim method, based on the multi-block analysis of ANOVA matrices, was used here to evaluate the impact of experimental factors on the responses from the different sensors tested.

3.
Anal Chim Acta ; 642(1-2): 6-11, 2009 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-19427453

RESUMEN

The octane number rating of a gasoline gives an indication of the gasoline performances, under various engine conditions. Two different ratings are included: Research Octane Number (RON) and Motor Octane Number (MON). The standard laboratory method for octane number determination is the knock engine method in which a gasoline is burned and its combustion characteristics compared to known standards. This method is time consuming and labor intensive, and provides no ability for real time control of production. NIR can be applied in real time directly in process monitoring or as a laboratory procedure. Near infrared spectra of gasoline samples were collected thanks to four different short wavelengths near infrared analysers, built with strictly the same technology. The aim of this study was to transfer the calibration built on one spectrometer to the other ones. We applied the external parameter orthogonalisation (EPO) correction to get rid of the apparatus influence on information contained in spectra. By this method, we managed to improve prediction values of two major gasolines' properties, i.e. Research and Motor Octane Number.

4.
Anal Chim Acta ; 642(1-2): 163-70, 2009 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-19427472

RESUMEN

As the jojoba oil was used in cosmetic, pharmaceutical, dietetic food, animal feeding, lubrication, polishing and bio-diesel fields, it was important to study its aging at high temperature by oxidative process. In this work a FT-MIR methodology was developed for monitoring accelerate oxidative degradation of jojoba oils. Principal component analysis (PCA) was used to differentiate various samples according to their origin and obtaining process, and to differentiate oxidative conditions applied on oils. Two spectroscopic indices were calculated to report simply the oxidation phenomenon. Results were confirmed and deepened by multivariate curve resolution-alternative least square method (MCR-ALS). It allowed identifying chemical species produced or degraded during the thermal treatment according to a SIMPLISMA pretreatment.


Asunto(s)
Espectroscopía Infrarroja por Transformada de Fourier/métodos , Ceras/química , Calor , Análisis de los Mínimos Cuadrados , Análisis Multivariante , Oxidación-Reducción , Análisis de Componente Principal , Programas Informáticos , Factores de Tiempo
5.
Int J Pharm ; 378(1-2): 23-9, 2009 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-19465095

RESUMEN

Over the years, different formulation technologies intended for gastro retentive dosage delivery were investigated and patented. The aim of this study was to develop an innovative floating gastro retentive dosage form (GRDF). The developed technology induces a low-density dosage form containing high active pharmaceutical ingredient (API) concentration by using a hydrophobic dusty powder excipient under specific conditions. The new dosage form was obtained by state of the art wet granulation manufacturing process. An experimental design using a discrete variable and four mixture variables was conducted in order to optimize API concentration and buoyancy of the new dosage form. An apparatus was developed to measure the apparent density of floating tablet. The GRDF was characterized for apparent density, buoyancy, porosity and dissolution using in vitro experimentations.


Asunto(s)
Excipientes/química , Preparaciones Farmacéuticas/administración & dosificación , Tecnología Farmacéutica/métodos , Administración Oral , Química Farmacéutica/métodos , Interacciones Hidrofóbicas e Hidrofílicas , Porosidad , Solubilidad , Comprimidos
6.
Talanta ; 77(5): 1748-56, 2009 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-19159793

RESUMEN

One of the most suitable analytical techniques used for edible oil quality control is Fourier transform mid infrared spectroscopy (FT-MIR). FT-MIR spectroscopy was used to continuously characterize the aging of various edible oils thanks to a specific aging cell. There were differences in the spectra of fresh and aged oils from different vegetable sources, which provide the basis of a method to classify them according to the oxidative spectroscopic index value. The use of chemometric treatment such as multivariate curve resolution-alternative least square (MCR-ALS) made it possible to extract the spectra of main formed and degraded species. The concentration profiles gave interesting information about the ability of the various oils to support the oxidative treatment and showed that all oils present the same aging process. Both methods led to concordant results in terms of induction times determined by the oxidative spectroscopic index and the appearance of oxidation products revealed by MCR-ALS.


Asunto(s)
Análisis de los Alimentos , Aceites de Plantas/normas , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Conservación de Alimentos , Oxidantes , Oxidación-Reducción
7.
Sci Total Environ ; 407(7): 2390-403, 2009 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-19167742

RESUMEN

Sewage treatment plants produce wastes resulting from the organic matter concentration in the form of sludge. A way of jointly treating and exploiting these increasing wastes jointly is the composting. Composting makes it possible to reduce volumes and the masses of wastes all while developing them in a product usable like organic soil enrichment. In this work, the composting process of an industrial sewage sludge composting plant was monitored to study the evolution of different physico-chemical parameters (temperature, moisture, pH, organic carbon, organic and inorganic nitrogen, organic carbon/organic nitrogen ratio, humic substances) and biochemical parameters (soluble fraction, hemicellulose, cellulose, lignin). Because these analyses are expensive and time consuming, we wanted to develop an alternative method to determine the maturity of compost related to compost properties with raw samples. Acceptable predictions were found for moisture, temperature, pH, organic carbon, organic carbon/organic nitrogen ratio, total-, organic- and ammoniacal nitrogen, fulvic- and humic acids and fulvic acids/humic acids ratio, but the error values were too high for the compost age to consider a quantification model. With regard to the biochemical parameters, this study is rather a preliminary test which shows the interest of the approach, but requires to be continued. Finally, the age of compost can be evaluated with Principal Component Analysis applied to NIR spectra.


Asunto(s)
Aguas del Alcantarillado/química , Suelo , Administración de Residuos/métodos , Carbono/análisis , Sustancias Húmicas/análisis , Concentración de Iones de Hidrógeno , Análisis de los Mínimos Cuadrados , Nitrógeno/análisis , Análisis de Componente Principal , Espectroscopía Infrarroja Corta , Temperatura
8.
Appl Spectrosc ; 62(7): 810-6, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18935833

RESUMEN

This study presents a new method for evaluating the oxidation of lubricating oils. An aging cell adapted to a Fourier transform infrared (FT-IR) spectrometer allows the continuous and direct study of the oxidative aging of base oils. During the test, oxidation bands appeared in the spectra (carbonyl bands around 1730 cm(-1)). The graphic representation of the carbonyl band modification--using a spectroscopic index--makes it possible to monitor the evolution of the lubricant composition. Comparing the oxidation constants, determined from the kinetic plots of several base oils, makes it possible to evaluate their relative sensitivity.

9.
Talanta ; 77(1): 200-9, 2008 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-18804621

RESUMEN

A new analytical method based on Fourier transformed infrared spectroscopy (FTIR) using chemometric tools to treat spectral data is proposed to study the degradation of aqueous phenolic solutions by photo-Fenton process. Obtained results were validated by high-performance liquid chromatography (HPLC) taken as a reference method. First a discrimination of the different steps of phenol degradation was possible by applying a principal component analysis (PCA). Then a description of the reaction evolution was successfully made using MCR-ALS, a multivariate curve resolution method which has permitted to obtain the concentration profiles of phenol and its photoproducts. Kinetics of their formation and disappearance described with this new approach are in agreement with HPLC results. This methodology may be a good alternative to classical analyses for monitoring of the degradation reactions because a lot of data are recorded and treated simultaneously. It shows how species concentration varies over time, informing thus on the reaction mechanism because a structural identification of products is possible through pure extracted spectra.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Peróxido de Hidrógeno/química , Hierro/química , Fenoles/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Cinética , Fotoquímica , Soluciones
10.
Talanta ; 75(4): 857-71, 2008 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-18585158

RESUMEN

This study was conducted to classify petroleum oils in terms of their biodegradation stage by using spectroscopic analysis associated to chemometric treatments. Principal Component Analysis (PCA) has been applied on infrared and UV fluorescence spectra of Brazilian and Pyrenean oils. For Brazil samples, the method allowed to distinguish the biodegraded oils from the non-affected ones. Pyrenean sampling including oils at different levels of biodegradation has been chosen to follow their alteration rate. PCA loadings have shown spectral regions which have differentiated oils after biodegradation whereas Simple-to-use Interactive Self-Modelling Mixture Analysis (SIMPLISMA) has permitted to obtain a repartition in terms of components families (saturated, aromatic and polar ones) characterizing chemical composition of oils at different biodegradation degrees. Results are in good agreement with conclusions of usual hydrocarbon biomarker analysis.


Asunto(s)
Aceites Combustibles/análisis , Análisis Espectral/métodos , Brasil , Mezclas Complejas/química , Europa (Continente) , Fluorescencia , Aceites Combustibles/microbiología , Cromatografía de Gases y Espectrometría de Masas , Análisis de Componente Principal , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier
11.
Appl Spectrosc ; 62(5): 583-90, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-18498701

RESUMEN

The combination of mid-infrared (MIR) spectroscopy with multivariate analysis provides an original approach to study the profile of virgin olive oils (VOOs) in relation to composition and geographical origin. Chemometric treatment of mid-infrared spectra (n=402) is assessed for quantification of fatty acids (14 components) and triacylglycerols (19 components) in VOO samples and for classification into six very geographically closed registered designations of origin (RDOs) of French VOO ("Aix-en-Provence", "Haute-Provence", "Vallée des Baux de Provence", "Nice", "Nîmes", and "Nyons"). Spectroscopic interpretation of regression vectors has shown that each RDO is correlated to one specific component of VOO according to their cultivar compositions. The results are satisfactory, in spite of the similarity of cultivar compositions between two denominations of origin ("Aix-en-Provence" and "Vallée des Baux de Provence"). Chemometric treatment of MIR spectra makes it possible to obtain similar results to those obtained by time-consuming analytical techniques such as gas chromatography (GC) and high-performance liquid chromatography (HPLC) and constitutes a fast and robust tool for authentication of these French VOOs.


Asunto(s)
Lípidos/análisis , Aceites de Plantas/química , Ácidos Grasos/análisis , Francia , Región Mediterránea , Aceite de Oliva , Aceites de Plantas/normas , Espectrofotometría Infrarroja , Triglicéridos/análisis
12.
Artículo en Inglés | MEDLINE | ID: mdl-17602857

RESUMEN

To better understand the composite character of irradiated alanine ESR spectra, a comparative study of few simple amino acids is performed in order to identify the different radio-induced radicals and their proportions. A dedicated spin-trapping method coupled with High Performance Liquid Chromatography (HPLC) is developed and carried out on irradiated alanine, glycine and valine; labeled or not. This study leads us to obtain different isolated trapped radical spectra where hyperfine coupling constants could be evaluated. For alanine, only two species are identified with relative proportions around 97 and 3% in contradiction with recent published articles. The main species has a particularity on its hyperfine coupling constants when labeled carbons are used. Very high hyperfine coupling constants are observed with the carboxylic acid function carbon for the three studied amino acid.


Asunto(s)
Alanina/química , Radiólisis de Impulso/métodos , Radiólisis de Impulso/tendencias , Cromatografía Líquida de Alta Presión , Espectroscopía de Resonancia por Spin del Electrón , Radicales Libres/química , Concentración de Iones de Hidrógeno , Magnetismo , Soluciones , Espectrofotometría Ultravioleta , Detección de Spin , Temperatura
13.
Anal Chim Acta ; 595(1-2): 136-44, 2007 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-17605993

RESUMEN

The authentication of virgin olive oil samples requires usually the use of sophisticated and time consuming analytical techniques. There is a need for fast and simple analytical techniques for the objective of a quality control methodology. Virgin olive oils present characteristic NIR spectra. Chemometric treatment of NIR spectra was assessed for the quantification of fatty acids and triacylglycerols in virgin olive oil samples (n=125) and for their classification (PLS1-DA) into five very geographically closed registered designations of origin (RDOs) of French virgin olive oils ("Aix-en-Provence", "Haute-Provence", "Nice", "Nyons" and "Vallée des Baux"). The spectroscopic interpretation of regression vectors showed that each RDO was correlated to one or two specific components of virgin olive oils according to their cultivar compositions. The results were quite satisfactory, in spite of the similarity of cultivar compositions between two denominations of origin ("Aix-en-Provence" and "Vallée des Baux"). Chemometric treatments of NIR spectra allow us to obtain similar results than those obtained by time consuming analytical techniques such as GC and HPLC, and constitute a help fast and robust for authentication of those French virgin olive oils.

14.
Presse Med ; 34(22 Pt 1): 1727-36, 2005 Dec 17.
Artículo en Francés | MEDLINE | ID: mdl-16374397

RESUMEN

Psoriasis is a common dermatosis that affects 3-5% of the European population. Current treatments offer considerable clinical benefits, but their use is limited due to tolerance problems. Recent years have seen the development of new treatments, used separately or in combination to improve the chronic lesions caused by this disease. T cells play an important role in the pathogenesis of psoriasis. Various techniques target the T cells and the immunological mechanisms involved in their activation. In 2005, treatment of psoriasis is directed essentially towards immunological pathways.


Asunto(s)
Psoriasis/terapia , Antiinflamatorios/uso terapéutico , Fármacos Dermatológicos/uso terapéutico , Humanos , Inmunosupresores/uso terapéutico , Fototerapia , Psoriasis/fisiopatología
15.
Artículo en Inglés | MEDLINE | ID: mdl-15741102

RESUMEN

Proton nuclear magnetic resonance spectroscopy ((1)H NMR), which has become an important tool for the study "in situ" of beta-cyclodextrin (beta-CD) complexes, was used to study and structurally characterize the inclusion complexes formed between beta-CD and isoproturon, fenuron, monuron and diuron. The high variation of the chemical shifts from the proton located inside the cavity (H-3, H-5 and H-6) coupled with the non variation of the one located outer sphere of the beta-CD (H-1, H-2 and H-4) provided clear evidence of the inclusion phenomena. Two-dimensional rotating frame Overhauser effect spectroscopy (ROESY) experiments were carried out to further support the proposed inclusion mode.


Asunto(s)
Diurona/química , Compuestos de Metilurea/química , Compuestos de Fenilurea/química , beta-Ciclodextrinas/química , Diurona/metabolismo , Espectroscopía de Resonancia Magnética , Compuestos de Metilurea/metabolismo , Estructura Molecular , Compuestos de Fenilurea/metabolismo , beta-Ciclodextrinas/metabolismo
16.
Int J Pharm ; 289(1-2): 117-31, 2005 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-15652205

RESUMEN

The purpose of this paper is to show how the utilization of Fourier Transform Infrared (FTIR) spectroscopy can be interesting in stability studying of cosmetic or pharmaceutical "oil in water" (O/W) emulsions. In this study temperature storage tests were performed to accelerate the aging process and evaluate the stability of five emulsions. Emulsions were analyzed by FTIR and classical methods (conductivity, viscosity, pH, texture analysis) in order to determine a method that would enable predicting the emulsion's stability. During the aging process, modifications of chemical functions are measured by FTIR (using spectrometric indices), such modifications included: a decrease of unsaturation index, an increase of carbonyl index and a broadening of the carbonyl band. This band was deconvoluted to evaluate the contribution of different species in the broadening phenomenon, which seems to be caused by the appearance of free fatty acids. Conductimetry seems to be the most sensitive technique to assess physical modifications during emulsion's aging. Concerning the most unstable emulsions, a progressive increasing of conductivity was observed several months before the emulsion destabilizes. Consequently, FTIR and conductimetry are two complementary techniques. Conductimetry is a useful technique to predict emulsion destabilization while FTIR allows the measurement of chemical modifications and helps to understand the chemical mechanisms which occur during the oxidation.


Asunto(s)
Cosméticos/normas , Formas de Dosificación , Evaluación Preclínica de Medicamentos/métodos , Emulsiones/normas , Espectroscopía Infrarroja por Transformada de Fourier/tendencias , Factores de Tiempo , Cosméticos/química , Evaluación Preclínica de Medicamentos/tendencias , Estabilidad de Medicamentos , Emulsiones/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Temperatura , Conductividad Térmica
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(11): 2553-9, 2004 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-15294244

RESUMEN

FTIR and Raman vibrational spectroscopic techniques as well as DFT quantum chemical calculation were used for characterizing conformational changes of phenylurea (a herbicide parent molecule) occurring from solid state to aqueous medium. Experimental infrared frequencies were assigned on the base of urea and benzenic derivatives spectroscopic data available in the literature and vibrational normal modes analytical calculation at the fully optimized geometry. Investigation of isotopic and solvent effects has revealed that the structure of phenylurea is particularly sensitive to the electrostatic environment via hydrogen non covalent bonds. The ability of beta-cyclodextrin (beta-CD) to form host-guest inclusion complex with phenylurea in the solid state was also evidenced by significant frequency shifts observed in the 1400-1800 cm(-1) spectral range.


Asunto(s)
Compuestos de Fenilurea/química , beta-Ciclodextrinas/química , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman
18.
Appl Spectrosc ; 58(6): 711-8, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15198824

RESUMEN

The interaction of diuron and isoproturon herbicides with beta-cyclodextrin is conducive to the formation of inclusion compounds in aqueous solution as well as in the solid state. The physico-chemical study of these complexes was carried out by various analytical techniques such as ultraviolet (UV), Fourier transform infrared (FT-IR), Raman, X-ray diffraction, and 1H-NMR (nuclear magnetic resonance) spectroscopies. The existence of inclusion complexes in water solution between the beta-cyclodextrin and each of the herbicides was revealed by electronic absorption and 1H-NMR spectroscopies. A 1:1 stoichiometry was determined for both complexes in aqueous medium from UV absorption spectra by using the Benesi-Hildebrand method; the relative stability constants at room temperature were calculated at 2700 +/- 300 L mol(-1) and 750 +/- 50 L mol(-1) for isoproturon and diuron, respectively. In the solid state, inclusion processes with beta-cyclodextrin were characterized by means of infrared and Raman techniques and confirmed by X-ray diffraction spectra.


Asunto(s)
Ciclodextrinas/química , Diurona/química , Herbicidas/química , Compuestos de Metilurea/química , Compuestos de Fenilurea , Espectrofotometría/métodos , beta-Ciclodextrinas , Ciclodextrinas/análisis , Soluciones , Procesos Estocásticos , Agua/química , Difracción de Rayos X/métodos
19.
Artículo en Inglés | MEDLINE | ID: mdl-15134733

RESUMEN

Bitumen, as each organic substance, is a product which alters over time. Indeed, roads deteriorate under the effect of several phenomena. A number of studies have been undertaken to increase the quality of road's coating, mostly by adding polymer to bitumen. This work was based on the study, by electron paramagnetic resonance (EPR), FTIR and Synchronous UV fluorescence, of different base and modified bitumens after different treatments used to simulate the ageing (gamma irradiation, thermal treatment). Our purpose was to compare and correlate the results obtained by different techniques to improve the knowledge of bitumen's reactivity and evolution submitted to ageing phenomena.


Asunto(s)
Espectroscopía de Resonancia por Spin del Electrón , Hidrocarburos , Estrés Oxidativo , Espectrometría de Fluorescencia , Espectroscopía Infrarroja por Transformada de Fourier , Rayos gamma , Calor , Oxidación-Reducción , Factores de Tiempo , Rayos Ultravioleta
20.
Am J Hematol ; 69(3): 214-8, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11891810

RESUMEN

Hemoglobin Lyon-Bron was found in two members of a family of German ascent presenting with a moderate normocytic anemia. In this alpha 2 globin variant, the N-terminal valine of the chain was replaced by an alanine. Electrospray mass spectrometry of the alpha chain showed that, as normally, the initiator methionine was cleaved during globin processing but that the N alpha-terminal group was totally acetylated. This resulted in structural modifications of a region crucial for oxygen binding. As a consequence, hemoglobin Lyon-Bron displayed both a reduced chloride effect and a decreased oxygen affinity, this last point explaining the apparent anemia.


Asunto(s)
Globinas/genética , Hemoglobinas Anormales/genética , Oxígeno/metabolismo , Acetilación , Adolescente , Sustitución de Aminoácidos , Sitios de Unión/genética , Cloro/metabolismo , Salud de la Familia , Femenino , Variación Genética , Globinas/química , Hemoglobinas Anormales/química , Humanos , Concentración de Iones de Hidrógeno , Ligandos , Masculino , Persona de Mediana Edad , Oxihemoglobinas , Espectrometría de Masa por Ionización de Electrospray , Volumetría
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...