Correction of geometrical distortions in bands of chromatography images

This paper presents a methodology for correcting band distortions in Thin-LayerChromatography (TLC) images. After the segmentation of image lanes, theintensity profile of each lane column is spatially aligned with a reference profileusing a modified version of the Correlation Optimized Warping (COW)algorithm. The proposed band correction methodology was assessed using 105profiles of TLC lanes. A set of features for band characterization was extractedfrom each lane profile, before and after band distortion correction, and was usedas input for three distinct one-class classifiers aiming at band identification. In allcases, the best results of band classification were obtained for the set lanes afterband distortion correction

J Fluorescence

The scope of this paper is to illustrate the need for an improved quality assurance in fluorometry. For this purpose, instrumental sources of error and their influences on the reliability and comparability of fluorescence data are highlighted for frequently used photoluminescence techniques ranging from conventional macro- and microfluorometry over fluorescence microscopy and flow cytometry to microarray technology as well as in vivo fluorescence imaging. Particularly, the need for and requirements on fluorescence standards for the characterization and performance validation of fluorescence instruments, to enhance the comparability of fluorescence data, and to enable quantitative fluorescence analysis are discussed. Special emphasis is dedicated to spectral fluorescence standards and fluorescence intensity standards

Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series

The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects.We thank generous funding from the European Research Council through an ERC Starting Grant (ERC2011-StG-279520-RASPA), the Spanish Ministry of Economy (CTQ2013-48396-P, CTQ2014-53486-R, CTQ2015-70135-REDT) and FEDER and Marie Curie IIF-625939 (LMRA) funding from European Union and Andalucía Region (FQM-1851)

Improving the Design and Application of Insulator-Based Dielectrophoretic Devices for the Assessment of Complex Mixtures

Dielectrophoresis (DEP) is an electrokinetic (EK) transport mechanism that exploits polarization effects when particles are exposed to a non-uniform electric field. This dissertation focused on the development of high-performance insulator-based DEP (iDEP) devices. A detailed analysis of the spatial forces that contribute to particle movement in an iDEP device is provided. In particular, this analysis shows how particle size and shape affects the regions where particles are likely to be retained due to dielectrophoretic trapping. The performance of these trapping regions was optimized using a systematic approach that integrates the geometrical parameters of the array of insulating structures. Devices that decrease the required electrical potential by ~80% where found. The optimization strategy enabled the detection of structures that promote and discourage particle trapping. By combining the best and worst structures in a single asymmetric structure, a novel iDEP device was designed. This device selectively enriches the larger particles in a sample and drives the smaller particles away from the enrichment region. A quick enrichment and elution of large cells was achieved. This is important when dealing with samples containing eukaryotic cells, which can be harmed by the electrical treatment. Yeast cells were successfully separated from polystyrene particles in under 40 seconds using this device and a high cell viability of 85% was achieved. Finally, an enhancement of traditional iDEP devices is proposed, where some insulating posts are replaced by conducting structures. That is, insulating and conductive posts are intimately combined within the same array. The performance of this hybrid device is presented to show the advantage of using insulating structures with microelectrodes in the same array to dominate particle movement

Hyperspectral Imaging for Fine to Medium Scale Applications in Environmental Sciences

The aim of the Special Issue “Hyperspectral Imaging for Fine to Medium Scale Applications in Environmental Sciences” was to present a selection of innovative studies using hyperspectral imaging (HSI) in different thematic fields. This intention reflects the technical developments in the last three decades, which have brought the capacity of HSI to provide spectrally, spatially and temporally detailed data, favoured by e.g., hyperspectral snapshot technologies, miniaturized hyperspectral sensors and hyperspectral microscopy imaging. The present book comprises a suite of papers in various fields of environmental sciences—geology/mineral exploration, digital soil mapping, mapping and characterization of vegetation, and sensing of water bodies (including under-ice and underwater applications). In addition, there are two rather methodically/technically-oriented contributions dealing with the optimized processing of UAV data and on the design and test of a multi-channel optical receiver for ground-based applications. All in all, this compilation documents that HSI is a multi-faceted research topic and will remain so in the future

The fate of colors in the 20th - 21st centuries: preserving the organic colorants in plastic artifacts

Objectos modernos e contemporâneos feitos de plástico são amplamente encontrados no património cultural. Presentemente, a sua preservação levanta questões críticas aos conservadores e cientistas uma vez que estes objectos podem facilmente sofrer degradação num curto espaço de tempo. Um dos fenómenos que pode alterar significativamente a aparência de objectos em plástico é a alteração de cor (descoloração). De um modo geral, a descoloração é habitualmente associada à degradação dos polímeros, contudo, os pigmentos, que são parte integrante das formulações do plástico, também podem desvanecer devido à exposição à luz. A identificação de objetos de plástico com pigmentos sensíveis à luz é um exercício bastante exigente devido à sensibilidade dos mesmos a alterações na cor. A caracterização dos corantes nos plásticos é normalmente realizada através de amostragem, métodos de extração e testagem destrutiva. Como alternativa, esta tese apresenta uma abordagem inovadora e multi- analítica baseada em espectroscopias que foi desenvolvida para a identificação in situ dos pigmentos em plásticos históricos. Esta metodologia compreendeu a utilização de microscopia ótica (MO), microespectrometria por fluorescência de raios X dispersiva de energias (μ-EDXRF), espectroscopia UV-Vis-NIR de reflectância, fotoluminescência (PL) e micro-espectroscopia de Raman (μ-Raman) na análise de obras de arte, objetos industriais e de uso diário, datados de 1950-2000s e pertencentes a coleções Portuguesas. Deste estudo resultou a identificação dos pigmentos comumente presentes na paleta de cor dos coloristas da indústria dos plásticos portuguesa: óxido de ferro (PR 101, α-Fe2O3), molibdato de cromato de chumbo (PR 104, Pb(Cr,Mo,S)O4), vermelho de cádmio (PR 108, Cd(S,Se); PR 113, (Cd,Hg)S), amarelo de cádmio (PY 37, CdS; PY 35; (Cd,Zn)S), branco de titânio (PW 6, TiO2 ambos rutilo e anátase), oxicloreto de bismuto (PW 14, BiOCl) e lacas do pigmento orgânico β-naftol (PR 48, PR 49, PR 53). Adicionalmente, foi também identificado um pigmento fora do comum, o pigmento perlascente plumbonacrite Pb5(CO3)3O(OH)2. Para todos os casos de estudo, μ-Raman foi a ferramenta chave para a caracterização dos pigmentos nos objetos de plástico, aportando dados conclusivos para a identificação dos mesmos. A impressão digital vibracional dos pigmentos orgânicos e inorgânicos foi adquirida com sucesso recorrendo à focagem do laser na superfície das partículas. A aquisição de dados espectrais de pigmentos com concentrações muito baixas (0.1 % a 5%, aproximadamente) à escala micro foi possível através de microscopia confocal, que faz parte do sistema do equipamento de μ-Raman. Adicionalmente, foi também possível obter informação sobre o polímero base (principalmente termoplásticos) e cargas. Os métodos analíticos desenvolvidos neste estudo deverão, em trabalhos futuros, facilitar a obtenção de informação complementar sobre estes objetos de plástico e permitir uma melhor identificação e avaliação do seu estado de conservação. Esta tese foca particularmente objectos de plástico vermelhos visto que estes foram identificados como os mais severamente afetados por alterações de cor. O estado avançado de desvanecimento identificado no pigmento β-naftol PR 53 mostrou a sua fraca estabilidade à luz em formulações de plástico. Esta situação, junto com as alterações de cor descritas em literatura para o pigmento PR 48 em objetos de plástico, sugere uma sensibilidade dos pigmentos vermelhos da família dos β-naftol ao desvanecimento. O PR 53 e os pigmentos vermelhos da família dos β-naftóis são pigmentos históricos facilmente encontrados em objetos do património cultural. No entanto, o conhecimento acerca da sua estabilidade a longo prazo e resistência à foto-degradação é limitado, especialmente para os casos onde os mesmos se encontram em polímeros, sendo que este conhecimento é essencial para a sua preservação. Neste estudo, a quantificação da foto-estabilidade para uma série de pigmentos vermelhos da família dos β-naftol foi realizada pela primeira vez, através do cálculo do rendimento quântico de fotodegradação (ΦR). Os valores obtidos variaram entre 3x10-6 e 4x10-5, indicativo de uma estabilidade relativamente boa à luz por parte das moléculas. Tendo em consideração que a estabilidade dos pigmentos não se limita exclusivamente ao pigmento em si, mas também à sua interação com o meio envolvente, foram realizados ensaios de envelhecimento por exposição à luz (λ>300 nm) do pigmento em solução, em pó e incorporado em polímeros de modo a avaliar o papel do meio na estabilidade à luz dos pigmentos e as vias pelas quais estes se degradam. Verificou-se que o ligante tem um impacto significativo na estabilidade do pigmento uma vez que se foi detetada uma maior sensibilidade à luz dos pigmentos PR 48 e PR 53 quando incorporados nos plásticos, comparativamente ao ensaio do pigmento em pó. Este novo conhecimento irá contribuir para o desenvolvimento de novas estratégias na conservação dos plásticos com estes pigmentos vermelhos fotossensíveis através da previsão do desvanecimento. Espectrometrias de massa (MS) por cromatografia em fase líquida e gasosa foram utilizadas na caracterização dos principais subprodutos da degradação. Observou-se uma fotodegradação significativa e a formação de compostos ftálicos e ftalatos nos pigmentos em solução e em pó.Modern and contemporary objects made of plastics are widely found in cultural heritage. Today, their preser- vation poses critical issues to conservators and scientists, as they can suffer from extensive degradation in a short time period. Color change (discoloration) is one of the alteration phenomena that can significantly affect their appearance. Discoloration is commonly associated with the degradation of polymers. However, pigments within plastics can also fade due to exposure to light. The identification of objects that contain light-sensitive pigments is demanding because of the sensitivity of plastics to color change. Normally sampling, extraction methods and destructive testing are required for the characterization of colorants in plastics. In this work, an innovative multi-analytical spectroscopic approach for the in situ identification of pigments in historical plastics was developed. Optical microscopy (MO), micro-energy dispersive X-ray fluo- rescence (μ-EDXRF), UV-Vis-NIR reflectance, photoluminescence (PL) and Raman microscopy (μ-Raman), were used for the analysis of artworks, industrial and daily objects dated from 1950s-2000s from Portuguese collections. A common colorists’ palette within the Portuguese plastics industry was identified: iron oxide (PR 101, α-Fe2O3), lead chromate molybdate (PR 104, Pb(Cr,Mo,S)O4), cadmium red (PR 108, Cd(S,Se); PR 113, (Cd,Hg)S) and cadmium yellow (PY 37, CdS; PY 35; (Cd,Zn)S) pigments, titanium whites (PW 6, TiO2 both rutile and anatase), bismuth oxychloride (PW 14, BiOCl) and organic β-naphthol lakes (PR 48, PR 49, PR 53). An exceptional pigment found was the pearlescent plumbonacrite pigment Pb5(CO3)3O(OH)2. In all the case studies, μ-Raman was the key analytical tool for pigment characterization in the plastic objects, providing conclusive data for their identification. The vibrational fingerprint of both inorganic and organic pigments was successfully recorded by focusing the laser beam on particle surfaces. The confocal microscopy system used in μ-Raman enabled the collection of spectral data from low concentrations of pigments (ap- proximately 0.1%-5%) on the micro-scale. In addition to pigments, information on the base polymer (mainly thermoplastics) and fillers was obtained. The analytical methods developed will facilitate the acquisition of complementary data from plastics allowing material identification and condition assessment in the future. This thesis focused on red pigmented plastic artifacts, as they were found to be severely faded among the studied objects. The identification of β-naphthol pigment lake PR 53 as a faded pigment highlighted its poor fastness in plastics, that together with the color change of PR 48 in plastic objects, reported in literature, suggests the particular susceptibility of β-naphthol red lakes to fading. PR 53, and the other β-naphthol reds, are historical pigments widely found in cultural heritage. However, little is known about their photodegradation and stability, especially when they are found in polymer media, and this knowledge is essential for their long- term preservation. For the first time, photodegradation quantum yields (ΦR) were calculated for a series of red pigments based on β-naphthol in order to quantify their photo-stability. ΦR values ranging from 3x10-6 to 4x10-5 were obtained, indicating relatively light-stable molecules. Bearing in mind that pigment fastness is not only related to the pigment itself, but also to its interaction with the confined environment, light-aging experiments (λ>300 nm) were conducted in solution, on powders, and in polymers to assess the role of the medium on the lightfastness of the pigments and their degradation pathways. A significant impact of the binder on their stability was found. Indeed, a higher sensitivity to light of PR 48 and PR 53 pigments, when incorporated in plastics than in powder, was observed. This new knowledge will contribute to the prediction of plastic fading and inform effective preventive conservation strategies for objects containing light- sensitive β-naphthol red pigments. Liquid- and gas-chromatography mass spectrometry (MS) were used for the characterization of the main degradation products. Extensive photodegradation was observed with the formation of phthalic compounds and phthalates in both solution and powder phases

Techniques and applications for preclinical SPECT

Two developments of the past decade have spurred the development of SPECT as a useful tool for preclinical research. Development of the pinhole collimator, and the growing library of imaging probes for use with SPECT beyond the traditional markers for perfusion or tumor metabolism have both increased the potential uses of SPECT for small animal research. The oblique geometry of pinhole rays originating toward the edges of the FOV results in incomplete sampling and poor image quality away from the pinhole orbit plane. Correction requires an orbit that includes an axial component of motion. A simple solution was developed by placing circular orbits at multiple axial locations along the length of the object. When reconstructed with an OSEM algorithm, the multiple projection sets improved data completeness and reconstructed image quality for simulated and experimental data. Pinhole collimators provide the greatest resolution and highest sensitivity when the object distance is minimized. In actuality, objects are placed some distance from the aperture to ensure that the camera field-of-view is large enough to avoid truncation. A method for improvement was tested by decreasing object distance and obtaining multiple offset projection sets. The two truncated projection sets were then be reconstructed with OSEM to create an image at with improved resolution. In addition to advancements in acquisition strategies, the work in this dissertation details two preclinical projects using the microSPECT camera. The microSPECT camera was used to examine the biodistribution of labeled monoclonal and polyclonal antibodies against the neutrophil protein myeloperoxidase. Mice injected with Staph-A were imaged at 24hr post infection with increased uptake of the tracer probe witnessed in the infected region. A second application required the measurement of hematocrit values using SPECT and labeled erythrocytes and plasma with 99mTc in ischemic rats. SPECT imaging of the labeled plasma and RBCs showed increases in hematocrit values within the ischemic lesion as defined from an HMPAO perfusion image. Moreover, the hematocrit value varied inversely with the perfusion deficit. For regions of poor blood flow, hematocrit was higher. During reperfusion, when flow was restored, or increased above normal levels, hematocrit levels dropped

An under-ice hyperspectral and RGB imaging system to capture fine-scale biophysical properties of sea ice

Sea-ice biophysical properties are characterized by high spatio-temporal variability ranging from the meso- to the millimeter scale. Ice coring is a common yet coarse point sampling technique that struggles to capture such variability in a non-invasive manner. This hinders quantification and understanding of ice algae biomass patchiness and its complex interaction with some of its sea ice physical drivers. In response to these limitations, a novel under-ice sled system was designed to capture proxies of biomass together with 3D models of bottom topography of land-fast sea-ice. This system couples a pushbroom hyperspectral imaging (HI) sensor with a standard digital RGB camera and was trialed at Cape Evans, Antarctica. HI aims to quantify per-pixel chlorophyll-a content and other ice algae biological properties at the ice-water interface based on light transmitted through the ice. RGB imagery processed with digital photogrammetry aims to capture under-ice structure and topography. Results from a 20 m transect capturing a 0.61 m wide swath at sub-mm spatial resolution are presented. We outline the technical and logistical approach taken and provide recommendations for future deployments and developments of similar systems. A preliminary transect subsample was processed using both established and novel under-ice bio-optical indices (e.g., normalized difference indexes and the area normalized by the maximal band depth) and explorative analyses (e.g., principal component analyses) to establish proxies of algal biomass. This first deployment of HI and digital photogrammetry under-ice provides a proof-of-concept of a novel methodology capable of delivering non-invasive and highly resolved estimates of ice algal biomass in-situ, together with some of its environmental drivers. Nonetheless, various challenges and limitations remain before our method can be adopted across a range of sea-ice conditions. Our work concludes with suggested solutions to these challenges and proposes further method and system developments for future research

New multi stimuli-responsive organic semiconductors for smart materials

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de Lectura: 20-07-2021La financiación de este trabajo ha provenido del Ministerio de Economía y Competitividad (CTQ2016-78557-R y PID2019-104125RB-I00

Remote sensing of snow : Factors influencing seasonal snow mapping in boreal forest region

Monitoring of snow cover in northern hemisphere is highly important for climate research and for operational activities, such as those related to hydrology and weather forecasting. The appearance and melting of seasonal snow cover dominate the hydrological and climatic patterns in the boreal and arctic regions. Spatial variability (in particular during the spring and autumn transition months) and long-term trends in global snow cover distribution are strongly interconnected to changes in Earth System (ES). Satellite data based estimates on snow cover extent are utilized e.g. in near-real-time hydrological forecasting, water resource management and to construct long-term Climate Data Records (CDRs) essential for climate research. Information on the quantitative reliability of snow cover monitoring is urgently needed by these different applications as the usefulness of satellite data based results is strongly dependent on the quality of the interpretation. This doctoral dissertation investigates the factors affecting the reliability of snow cover monitoring using optical satellite data and focuses on boreal regions (zone characterized by seasonal snow cover). Based on the analysis of different factors relevant to snow mapping performance, the work introduces a methodology to assess the uncertainty of snow cover extent estimates, focusing on the retrieval of fractional snow cover (within a pixel) during the spring melt period. The results demonstrate that optical remote sensing is well suited for determining snow extent in the melting season and that the characterizing the uncertainty in snow estimates facilitates the improvement of the snow mapping algorithms. The overall message is that using a versatile accuracy analysis it is possible to develop uncertainty estimates for the optical remote sensing of snow cover, which is a considerable advance in remote sensing. The results of this work can also be utilized in the development of other interpretation algorithms. This thesis consists of five articles predominantly dealing with quantitative data analysis, while the summary chapter synthesizes the results mainly in the algorithm accuracy point of view. The first four articles determine the reflectance characteristics essential for the forward and inverse modeling of boreal landscapes (forward model describes the observations as a function of the investigated variable). The effects of snow, snow-free ground and boreal forest canopy on the observed satellite scene reflectance are specified. The effects of all the error components are clarified in the fifth article and a novel experimental method to analyze and quantify the amount of uncertainty is presented. The five articles employ different remote sensing and ground truth data sets measured and/or analyzed for this research, covering the region of Finland and also applied to boreal forest region in northern Europe