387 research outputs found
Acidic Aqueous Solutions and Sulfate-Rich Mineralogy: Raman Investigations of Rio Tinto, Spain, a Model for Acid Mine Drainage and a Potential Martian Analog
En esta tesis doctoral he caracterizado soluciones acuosas sintĂ©ticas que se reproducen las condiciones extremas de las aguas de RĂo Tinto, Huelva, un ejemplo de entorno contaminado por drenaje ácido de mina, considerado como un escenario geo/bio/mineralĂłgico unico en nuestro planeta que ofrece situaciones comparables a las de Marte. He analizado muestras naturales de agua del rĂo usando espectroscopia Raman; en concreto, he estudiado las relaciones de equilibrio y especiaciĂłn, y las propiedades de transporte de materia. TambiĂ©n he caracterizado eflorescencias ricas en sulfato de RĂo Tinto utilizando espectroscopĂa Raman como herramienta fundamental, además de otras tĂ©cnicas complementarias como la reflectancia en el infrarrojo cercano y el visible (VNIR) y la difracciĂłn de rayos-X. He desarrollado rutinas de procesado automático de datos para obtener la máxima informaciĂłn de los espectros Raman y minimizar la contribuciĂłn del ruido y otras interferencias en los espectros.Departamento de FĂsica de la Materia Condensada, CristalografĂa y MineralogĂ
Recent Developments in Atomic Force Microscopy and Raman Spectroscopy for Materials Characterization
This book contains chapters that describe advanced atomic force microscopy (AFM) modes and Raman spectroscopy. It also provides an in-depth understanding of advanced AFM modes and Raman spectroscopy for characterizing various materials. This volume is a useful resource for a wide range of readers, including scientists, engineers, graduate students, postdoctoral fellows, and scientific professionals working in specialized fields such as AFM, photovoltaics, 2D materials, carbon nanotubes, nanomaterials, and Raman spectroscopy
A New Representation for Spectral Data Applied to Raman Spectroscopy of Brain Cancer
Par sa nature infiltrative et son confinement derrière la barrière hémo-encéphalique, le cancer primaire du cerveau est l’une des néoplasies les plus difficiles à diagnostiquer et traiter. Son traitement repose sur la résection chirurgicale maximale. La spectroscopie Raman, capable d’identifier en temps réel des régions cancéreuses qui apparaîtraient normales à l’œil nu, promet d’améliorer considérablement le guidage neurochirurgical et maximiser la résection de la masse tumorale. Cependant, le signal Raman est très complexe à interpréter : les systèmes Raman peuvent maintenant capter des signaux de grande qualité que les méthodes analytiques actuelles ne parviennent pas à interpréter de manière reproductible. Ceci constitue une barrière importante à l’acceptation de la spectroscopie Raman par les médecins et les chercheurs œuvrant sur le cancer du cerveau.
L’objectif de ce travail est de développer une méthode robuste d’ingénierie des variables (« Feature engineering ») qui permettrait d’identifier les processus moléculaires exploités par les systèmes Raman pour différentier les régions cancéreuses des régions saines lors de chirurgies cérébrales.
Tout d’abord, nous avons identifié les régions Raman ayant une haute spécificité à notre problématique clinique par une revue systématique de la littérature. Un algorithme d’ajustement de courbe a été développé afin d’extraire la forme des pics Raman dans les régions sélectionnées. Puis, nous avons élaboré un modèle mathématique qui tient compte de l’interactivité entre les molécules de l’échantillon interrogé, ainsi qu’entre le signal Raman et l’âge du patient opéré. Pour valider le modèle, nous avons comparé sa capacité à compresser le signal avec celle de l’analyse en composante principale (ACP), le standard en spectroscopie Raman. Finalement, nous avons appliqué la méthode d’ingénierie des variables à des spectres Raman acquis en salle d’opération afin d’identifier quels processus moléculaires indiquaient la présence de cancer.
Notre méthode a démontré une meilleure rétention d’information que l’ACP. En l’appliquant aux spectres Raman in vivo, les zones denses en cellules malignes démontrent une expression augmentée d’acides nucléiques ainsi que de certaines protéines, notamment le collagène, le tryptophan et la phénylalanine. De plus, l’âge des patients semble affecter l’impact qu’ont certaines protéines, lipides et acides nucléiques sur le spectre Raman. Nos travaux révèlent l’importance d’une modélisation statistique appropriée pour l’implémentation clinique de systèmes Raman chirurgicaux.----------ABSTRACT
Because of its infiltrative nature and concealment behind the blood-brain barrier, primary brain cancer remains one of the most challenging oncological condition to diagnose and treat. The mainstay of treatment is maximal surgical resection. Raman spectroscopy has shown great promise to guide surgeons intraoperatively by identifying, in real-time, dense cancer regions that appear normal to the naked eye. The Raman signal of living tissue is, however, very challenging to interpret, and while most advances in Raman systems targeted the hardware, appropriate statistical modeling techniques are lacking. As a result, there is conflicting evidence as to which molecular processes are captured by Raman probes. This limitation hinders clinical translation and usage of the technology by the cancer-research community.
This work focuses on the analytical aspect of Raman-based surgical systems. Its objective is to develop a robust data processing pipeline to confidently identify which molecular phenomena allow Raman systems to differentiate healthy brain and cancer during neurosurgeries.
We first selected high-yield Raman regions based on previous literature on the subject, resulting in a list of reproducible Raman bands with high likelihood of brain-specific Raman signal. We then developed a peak-fitting algorithm to extract the shape (height and width) of the Raman signal at those specific bands. We described a mathematical model that accounted for all possible interactions between the selected Raman peaks, and the interaction between the peaks’ shape and the patient’s age. To validate the model, we compared its capacity to compress the signal while maintaining high information content against a Principal Component Analysis (PCA) of the Raman spectra, the fields’ standard. As a final step, we applied the feature engineering model to a dataset of intraoperative human Raman spectra to identify which molecular processes were indicative of brain cancer.
Our method showed better information retention than PCA. Our analysis of in vivo Raman measurement showed that areas with high-density of malignant cells had increased expression of nucleic acids and protein compounds, notably collagen, tryptophan and phenylalanine. Patient age seemed to affect the impact of nucleic acids, proteins and lipids on the Raman spectra. Our work demonstrates the importance of appropriate statistical modeling in the implementation of Raman-based surgical devices
Descriptive and predictive assessment of enzyme activity and enzyme related processes in biorefinery using IR spectroscopy and chemometrics
Method development for the extraction of six bisphenols in serum by LC-MS/MS
Bisphenols are a class of chemicals characterized by two phenol groups bonded to a carbon chain or other chemical groups. These chemical substances are applied in everyday products such as plastics, canned goods, thermal paper, and medical devices. Bisphenol A (BPA) is the most studied compound out of the bisphenol family, and exposure to BPA at low concentrations can induce endocrine-disrupting processes affecting the endocrine system and human reproductive capabilities. When two phenol groups react with acetone (CH3COCH3), Bisphenol A (-cetone) is formed. By reacting two phenol groups with other functional groups, such as formaldehyde (CH2O) and sulfonyl (SO2), other bisphenols like Bisphenol F (-ormaldehyde) and Bisphenol S (-ulfonyl) are synthesized. The regulation of BPA has led to its replacement with other bisphenol analogs, such as BPF and BPS, which can have similar negative impacts on human health. Therefore, it is interesting to develop a method for quantifying low concentrations of various bisphenols in biological samples.
In this study, a preparation method was developed for the quantification of six bisphenols (BPs) in serum samples by LC-MS/MS. The six BPs of interest are: Bisphenol A (BPA; 4,4′-(propane-2,2-diyl)diphenol), Bisphenol AF (BPAF; 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphenol), Bisphenol E (BPE; 4,4'-ethylidenebisphenol), Bisphenol F (BPF; 4-[(4-hydroxyphenyl)methyl]phenol), Bisphenol S (BPS; 4-(4-hydroxyphenyl)sulfonylphenol) and Bisphenol Z (BPZ; 4-[1-(4-hydroxyphenyl)cyclohexyl]phenol). The sample preparation method was developed to obtain optimal sensitivity and selectivity of the BPs. The sample preparation included solid-phase extraction (SPE) to improve separation, enhance sensitivity, and reduce potential interferences and matrix effects.
The limit of quantification (LOQ) was found to be 2.1ng/mL for BPA, 0.1ng/mL for BPAF, 0.5ng/mL for BPE, 0.03ng/mL for BPF, 0.2ng/mL for BPS, and 0.2ng/mL for BPZ. Recovery testing was performed to evaluate the accuracy and correction of analyte loss during the extraction method. The robustness was evaluated by analyzing a pre-spiked serum sample with a fixed concentration of 500ng/mL multiple times (n=6) to evaluate the precision and variation in the measurements of the same sample. Lastly, the method was tested on real serum samples from Argentina. The conclusion is that further optimization is needed as the method is not sufficiently sensitive enough to quantify low concentrations of BPs in serum samples
Roadmap for Optical Tweezers 2023
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nanoparticle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration
Roadmap for optical tweezers
ArtĂculo escrito por un elevado nĂşmero de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboraciĂłn, si le hubiere, y los autores pertenecientes a la UAMOptical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space explorationEuropean Commission (Horizon 2020, Project No. 812780
Roadmap for optical tweezers
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.journal articl
Selected Papers from the 1st International Electronic Conference on Biosensors (IECB 2020)
The scope of this Special Issue is to collect some of the contributions to the First International Electronic Conference on Biosensors, which was held to bring together well-known experts currently working in biosensor technologies from around the globe, and to provide an online forum for presenting and discussing new results. The world of biosensors is definitively a versatile and universally applicable one, as demonstrated by the wide range of topics which were addressed at the Conference, such as: bioengineered and biomimetic receptors; microfluidics for biosensing; biosensors for emergency situations; nanotechnologies and nanomaterials for biosensors; intra- and extracellular biosensing; and advanced applications in clinical, environmental, food safety, and cultural heritage fields
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