Aggregated functional data model for Near-Infrared Spectroscopy calibration and prediction

Calibration and prediction for NIR spectroscopy data are performed based on a functional interpretation of the Beer-Lambert formula. Considering that, for each chemical sample, the resulting spectrum is a continuous curve obtained as the summation of overlapped absorption spectra from each analyte plus a Gaussian error, we assume that each individual spectrum can be expanded as a linear combination of B-splines basis. Calibration is then performed using two procedures for estimating the individual analytes curves: basis smoothing and smoothing splines. Prediction is done by minimizing the square error of prediction. To assess the variance of the predicted values, we use a leave-one-out jackknife technique. Departures from the standard error models are discussed through a simulation study, in particular, how correlated errors impact on the calibration step and consequently on the analytes' concentration prediction. Finally, the performance of our methodology is demonstrated through the analysis of two publicly available datasets.Comment: 27 pages, 7 figures, 7 table

Estimation of in-situ fluid properties from the combined interpretation of nuclear, dielectric, optical, and magnetic resonance measurements

During the last few decades, the quantification of hydrocarbon pore volume from borehole measurements has been widely studied for reservoir descriptions. Relatively less effort has been devoted to estimating in-situ fluid properties because (1) acquiring fluid samples is expensive, (2) reservoir fluids are a complex mixture of various miscible and non-miscible phases, and (3) they depend on environmental factors such as temperature and pressure. This dissertation investigates the properties of fluid mixtures based on various manifestations of their electromagnetic properties from the MHz to the THz frequency ranges. A variety of fluids, including water, alcohol, alkane, aromatics, cyclics, ether, and their mixtures, are analyzed with both laboratory experiments and numerical simulations. A new method is introduced to quantify in-situ hydrocarbon properties from borehole nuclear measurements. The inversion-based estimation method allows depth-continuous assessment of compositional gradients at in-situ conditions and provides thermodynamically consistent interpretations of reservoir fluids that depend greatly on phase behavior. Applications of this interpretation method to measurements acquired in two field examples, including one in a gas-oil transition zone, yielded reliable and verifiable hydrocarbon compositions. Dielectric properties of polar liquid mixtures were analyzed in the frequency range from 20 MHz to 20 GHz at ambient conditions. The Havriliak-Negami (HN) model was adapted for the estimation of dielectric permittivity and relaxation time. These experimental dielectric properties were compared to Molecular Dynamics (MD) simulations. Additionally, thermodynamic properties, including excess enthalpy, density, number of hydrogen bonds, and effective self-diffusion coefficient, were computed to cross-validate experimental results. Properties predicted from MD simulations are in excellent agreement with experimental measurements. The three most common optical spectroscopy techniques, i.e. Near Infrared (NIR), Infrared, and Raman, were applied for the estimation of compositions and physical properties of liquid mixtures. Several analytical techniques, including Principal Component Analysis (PCA), Radial Basis Functions (RBF), Partial Least-Squares Regression (PLSR), and Artificial Neural Networks (ANN), were separately implemented for each spectrum to build correlations between spectral data and properties of liquid mixtures. Results show that the proposed methods yield prediction errors from 1.5% to 22.2% smaller than those obtained with standard multivariate methods. Furthermore, the errors can be decreased by combining NIR, Infrared, and Raman spectroscopy measurements. Lastly, the ¹H NMR longitudinal relaxation properties of various liquid mixtures were examined with the objective of detecting individual components. Relaxation times and diffusion coefficients obtained via MD simulations for these mixtures are in agreement with experimental data. Also, the ¹H-¹H dipole-dipole relaxations for fluid mixtures were decomposed into the relaxations emanate from the intramolecular and intermolecular interactions. The quantification of intermolecular interactions between the same molecules and different molecules reveals how much each component contributes to the total NMR longitudinal relaxation of the mixture as well as the level of interactions between different fluids. Both experimental and numerical simulation results documented in this dissertation indicate that selecting measurement techniques that can capture the physical property of interest and maximize the physical contrasts between different components is important for reliable and accurate in-situ fluid identificationPetroleum and Geosystems Engineerin

Olive oil nutritional labeling by using Vis/NIR spectroscopy and compositional statistical methods

Food nutritional labeling is compulsory in the European Union since 13 December 2016. The olive oil fatty acid composition shows high variation depending mainly on the variety. Thus, olive oil nutritional labeling is problematic for the industry. Besides, the analysis of all batches of olive oil using the official methods is expensive. Therefore, the olive oil industry is seriously concerned about solutions for nutritional labeling. In this study, a new rapid technique to measure the nutrients for the olive oil nutritional labeling, is assessed. A novel partial least squares (PLS) calibration model using log-ratio coordinates has been formulated and successfully tested for predicting the percentages of monounsaturated, saturated, and polyunsaturated fatty acids based on visible and near infrared spectroscopy. The model provided accuracy suitable for labeling, under the rules in force in the European Union. The error was generally much lower than the tolerance. Industrial relevance: The approach here proposed can be a suitable solution for olive oil nutritional labeling, which is a current challenge for the olive oil industry.Consejo Superior de Investigaciones Científicas 20137R065Ministerio de Economía y Competitividad MTM2015-65016-C2-1(2)-

Exoplanets: Possible Biosignatures

The ancestor philosophers' dream of thousands of new worlds is finally realised: about 3500 extrasolar planets have been discovered in the neighborhood of our Sun. Most of them are very different from those we used to know in our Solar System. Others orbit their parent star inside the belt known as Habitable Zone where a rocky planet with the appropriate climate could have the availability of liquid water on its surface. Those planets, in HZ or not, will be the object of observation that will be performed by new space-/ground-based instrumentation. Space missions, such as JWST and the very recently proposed ARIEL (ESA M-Class Mission), or ground based instruments (SPHERE@VLT, GPI@GEMINI and EPICS@ELT) have been proposed and built to measure the atmospheric transmission, reflection and emission spectra over a wide wavelength range. Most of exoplanets have local counterparts in the Solar System planets that are available for comparative studies, but there are also interesting outsider cases like super Earths. In our own system, proto-planet evolution was flanked by an active prebiotic chemistry that brought about the emergency of life on the Earth. The search for life signatures requires the knowledge of planet atmospheres, main objective of future exoplanetary space explorations. As, for now, we have only one example of life in the universe, we are bound to study terrestrial organisms to assess possibilities of life on other planets and guide our search for possible extinct or extant life on other planetary bodies. The planet atmosphere characteristics and possible biosignatures will be inferred by studying such composite spectrum in order to identify the emission/absorption lines/bands from atmospheric molecules as water, carbon monoxide, methane, ammonia etc.Comment: Accepted, PoS-SISSA (2017), paper presented at the Mondello Workshop 2016 on "Frontier Research in Astrophysics - II", Franco Giovannelli (Ed.

Effect of Extrusion Parameters on Properties of Powder Coatings Determined by Infrared Spectroscopy

In polymer extrusion, compounding is a continuous mixing process that is also used to produce highly reactive powder coatings. A premixed batch of powder coating is added to the feeding section and extruded, preferably by a co-rotating twin-screw extruder. One essential parameter in the processing of highly reactive materials is the melt temperature: If it is too high, pre-reactions occur during the extrusion process, which may cause high rejection rates. We studied the melt temperature of an epoxy/carboxyl-based powder coating using a retractable thermocouple at 3 different axial positions along the barrel of a ZSK34 co-rotating twin-screw extruder. The influence of different processing conditions on the reactivity of a highly reactive powder coating was examined by infrared spectroscopy and differential scanning calorimetry. Furthermore, the specific energy input and the color change in the finished powder coating at different processing points were investigated. Multivariate data analysis was used to correlate mid-infrared spectra, melt temperatures, specific energy inputs, enthalpies of reaction and changes in color

Influence of 1,3-dimethylimidazolium chloride on the solubility of lithium bromide in water for absorption refrigeration and heat pumps

The effect of the 1,3-dimethylimidazolium chloride ([Dmim][Cl]) on the solubility of lithium bromide (LiBr) in water is analyzed. The solubility curve of ternary water/(LiBr+[Dmim][ Cl]), with 3 % and 6 % of [Dmim][Cl] in the absorbent, has been determined using a visual- polythermal method in the range from (0 to 90) ºC. To explain the role of the ionic liquid in the solubility of the LiBr, a multivariant curve resolution method was applied to near-infrared spectra of the ternary solutions and H2O/LiBr at room temperature within a wide composition range. The solubility results show that, in the range from 0.60 to 0.65 in absorbent mass faction, corresponding to the typical composition in the absorber inlet, the temperature decrease between 11 ºC and 13 ºC with 3 % of IL, and between 15 ºC and 20 ºC with 6 % of IL. Spectral calculation results show that in the ternary mixture, the amount of water that remains as bulk water in the presence of LiBr is higher than in the binary mixture. This suggests interactions between both species.The authors are grateful to the Spanish Ministry of Science and Innovation (PID2020- 119004RB-C21), the Diputació de Tarragona, and the Universitat Rovira i Virgili for financial support

Rapid and innovative instrumental approaches for quality and authenticity of olive oils

The quality of virgin olive oils is assessed through the determination of several analytical parameters, whose values must be within the ranges established by the different institutions involved. In addition to official methods, there is a strong need for simple, rapid, and environmentally friendly techniques for the quality control of virgin olive oils and for addressing the challenging task of determining geographical origin and detecting adulterants. Toward this purpose, some of the most interesting applications based on optical spectroscopic techniques, on the measurement of electrical characteristics and on the use of instruments equipped with electronic chemical sensors, including also other promising techniques are herein discussed. These techniques, adequately coupled with an appropriate statistical approach, appear to be promising for assessment of several quality-related parameters. The prediction of sensory attributes and of the oxidative status of virgin olive oils have also been reviewed by adopting these selected techniques, which are also considered to be potentially appropriate solutions for identification of the geographical origin of virgin olive oils and to assess their adulteration with cheaper oils. Overall, the techniques discussed are promising and cutting-edge approaches for the establishment of useful portable instruments for in situ monitoring of the quality of virgin olive oils. Practical applications: The simple, rapid, and environmentally friendly analytical approaches discussed herein represent promising analytical tools for assuring the authenticity and monitoring the quality of virgin olive oils. Such innovative techniques and tools need to be ring-tested and validated. Some innovative reviewed approaches will permit to develop useful portable instruments able to perform in situ appropriate controls also by small laboratories or olive oil mills with limited technical facilities. These equipments will be potentially usable also by trained \u201cnon-professional analytical skilled\u201d people. Some other approaches, rapid but more expensive, will be applicable mainly by quality control labs and will increase the number of samples analyzed per day, thus fostering laboratory proficiency and an effective fighting against olive oil fraud

Fourier transform infrared spectroscopy, a powerful tool to monitor biopharmaceuticals production

A Escherichia coli é o microorganismo mais usado como hospedeiro para a produção de produtos recombinantes, tais como plasmídeos usados para terapia génica e vacinação de ADN. Desta forma, torna-se importante compreender as relações metabólicas complexas e a bioprodução de plasmídeo, que ocorre em ambientes de cultura dinâmicos, a fim de controlar e optimizar o desempenho do sistema de expressão recombinante. O objectivo principal deste trabalho consiste em avaliar a potencialidade da espectroscopia FT-IR para monitorizar e caracterizar a produção do plasmídeo pVAX-LacZ em culturas recombinantes de E. coli, nomeadamente para extrair informação relacionada com as variáveis críticas (biomassa, plasmídeo, fontes de carbono e acetato) e informação metabólica da célula hospedeira E. coli. Para tal, culturas de E. coli com diferentes concentrações de glucose e glicerol e diferentes estratégias de cultivo (batch e fed-batch) foram monitorizadas por espectroscopia de infravermelho perto (NIR) e de infravermelho médio (MIR). Tanto a espectroscopia NIR com a MIR permitiram extrair informação sobre as variáveis críticas do bioprocesso, através da construção de modelos de regressão por mínimos quadrados parciais, que resultaram em elevados coeficientes de regressão e baixos erros de previsão. A abordagem NIR apresenta a vantagem de aquisição em tempo real das variáveis do bioprocesso, já a abordagem MIR permite a leitura simultânea de centenas de amostras de várias culturas ao mesmo tempo através do uso multi-microplacas, sendo muito vantajosa nos casos de micro-bioreactores usados para optimização. Para além disso, como os espectros MIR apresentam mais informação do que os espectros NIR, uma vez que representam os modos de vibração fundamentais das biomoléculas, enquanto que os espectros NIR representam sobreposições e combinações de vibrações, os dados espectrais MIR também permitiram a aquisição de informação bioquímica ao longo das culturas de E. coli a partir da análise das componentes principais (PCA) bem como do estudo das características bioquímicas, tais como as reservas de glicogénio e os níveis de transcrição aparente. Portanto, a espectroscopia FT-IR apresenta assim características relevantes para a compreensão e monitorização do processo de produção de culturas recombinantes, sendo, de acordo com Quality-by-Design e Process Analytical Technology, muito importante para fins de controlo e optimização.Escherichia coli is the most used microorganism as host for the production of recombinant products, such as plasmids used for gene therapy and DNA vaccination. Therefore, it is important to understand the complex metabolic relationships and the plasmid bioproduction process occurring in dynamic culture environments, in order to control and optimize the performance of the recombinant expression system. The main goal of this work is to evaluate the potential of Fourier Transform Infrared (FT-IR) spectroscopy to monitor and characterize recombinant E. coli cultures producing the plasmid model pVAX-LacZ, namely to extract information concerning the critical variables (biomass, plasmid, carbon sources and the by-product acetate) and metabolic information regarding the host E. coli. To achieve that cultures of E. coli conducted with different mixture of glucose and glycerol and different cultivation strategies (batch and fed-batch) were monitored in-situ by a fiber optic probe in near- infrared (NIR) and of the cell pellets in at-line in high-throughput mode by mid-infrared (MIR) spectroscopy. Both NIR and MIR spectroscopy setup enabled to extract information regarding the critical variables of the bioprocess by the implementation of partial least square regression models that result in high regression coefficients and low prediction errors. The NIR setup presents the advantage of acquiring in real time the knowledge of the bioprocess variables, where the at-line measurements with the MIR setup presents more advantageous in cases of micro-bioreactors used in optimization protocols, enabling the simultaneously information acquisition of hundreds samples by using multi-microplates. Furthermore, as the MIR spectra presents more information than the NIR spectra, since it represents the fundamental vibration modes of biomolecules while the NIR spectra represents overtones and combinations of vibrations, the MIR data also enabled to acquire biochemical information along the E. coli cultures as pointed out in an principal component analysis and by the estimation of biochemical features as glycogen reserves and apparent transcriptional levels. Therefore, FT-IR spectroscopy presents relevant features towards the understanding and monitoring of the production process of recombinant cultures for control and optimization purposes, in according to the Quality-by-Design and the Process Analytical Technology