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In this work, we propose the use of molecular emission of calcium fluoride (CaF) by laser induced breakdown spectroscopy (LIBS) to obtain quantitative fluoride distribution images of teeth.

The aim of this protocol is to provide a strategy for studying the eukaryotic translatome of the soybean (Glycine max) symbiotic nodule. This paper describes methods optimized to isolate plant-derived polyribosomes and their associated mRNAs to be analyzed using RNA-sequencing. First, cytoplasmic lysates are obtained through homogenization in polysome- and RNA-preserving conditions from whole, frozen soybean nodules. Then, lysates are cleared by low-speed centrifugation, and 15% of the supernatant is used for total RNA (TOTAL) isolation. The remaining cleared lysate is used to isolate polysomes by ultracentrifugation through a two-layer sucrose cushion (12% and 33.5%). Polysome-associated mRNA (PAR) is purified from polysomal pellets after resuspension. Both TOTAL and PAR are evaluated by highly sensitive capillary electrophoresis to meet the quality standards of sequencing libraries for RNA-seq. As an example of a downstream application, after sequencing, standard pipelines for gene expression analysis can be used to obtain differentially expressed genes at the transcriptome and translatome levels. In summary, this method, in combination with RNA-seq, allows the study of the translational regulation of eukaryotic mRNAs in a complex tissue such as the symbiotic nodule.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS) are widely accepted techniques for direct sampling of biological materials for elemental analysis, with increasing applications being reported over the recent years. This review is focused on the calibration materials used to quantify trace elements in different biological samples such as soft tissues (for instance brain, liver, hair) and hard tissues (bones and teeth). The design of a correct calibration strategy relies on the choice of an adapted reference material that can be commercially available or prepared in-house, which will be reviewed here. A large variety of methods has been approached and considered promising over the years, and the development of matrix-matched reference biological materials seems now closer than ever and gives hope to even better quantitation using LIBS and LA-ICP-MS.

Ante un modelo intensivo y dependiente de insumos en la horticultura platense y sus consecuencias en la salud y en el medio ambiente, las verduras agroecológicas emergen como una opción de producción sustentable y saludable para los consumidores. Este artículo expone los resultados de un estudio sobre los factores generales que organizan la representación social de las verduras frescas en transición agroecológica, en dos circuitos cortos de comercialización en la ciudad de La Plata, Provincia de Buenos Aires. Nos preguntamos: ¿Qué atributos reconocen los consumidores en las verduras agroecológicas que motivan su elección? Y, ¿Qué cuestiones les brindan garantías de autenticidad agroecológica? El estudio se realizó con dispositivos cuantitativos y cualitativos con una selección aleatoria de 275 consumidores. Los resultados muestran similitudes agroecológicos comercializados a través de nodos de consumo del Movimiento de Trabajadores Excluidos y consumidores que compran en la feria Manos de la Tierra emplazada en la Facultad de Ciencias Agrarias y Forestales. Se comparten preocupaciones por la salud y la necesidad de acortar distancia entre productores y consumidores. Las diferencias se muestran en cuanto a sus posicionamientos políticos e ideológicos así como por su oportunidad de acceso a las verduras agroecológicas., Faced with an intensive and dependent model of inputs in horticulture in La Plata and its consequences on health and the environment, agro-ecological vegetables emerge as a sustainable and healthy production option for consumers. This article exposes the results of a study on the general factors that organize the social representation of fresh vegetables in agro-ecological transition, in two short marketing circuits in the city of La Plata, Province Buenos Aires. We question: What attributes do consumers recognize in agro-ecological vegetables that motivate their choice? What issues give them guarantees of agro-ecological authenticity? The study was conducted by means of quantitative and qualitative methods with a random selection of 275 consumers. The results show similarities and differences according to the type of marketing circuit: on the one hand the agroecological packs of products marketed through consumption groups of the Excluded Workers Movement and on the other hand, consumers who buy at the “Hands of the Earth” market located at the Faculty of Agricultural and Forestry Sciences. We look at health concerns and the need to shorten the gap between producers and consumers. The differences are shown in terms of the political and ideological positions of consumers as well as their opportunity to access agro-ecological vegetables., Facultad de Ciencias Agrarias y Forestales

Line broadening due to plasma processes or the instrument degrade spectral resolution leading to uncertainty in the elemental profile obtained by optical emission spectroscopy. A novel approach to quantify spectral interferences in laser-induced breakdown spectroscopy (LIBS) is introduced. This algorithm establishes a statistical interference factor (SIF) to quantify spectral interferences for individual line assignment in LIBS while using the full information provided by a spectrum. This factor combines fundamentals of plasma emission with a Bayesian analysis of the experimental spectrum using eventual prior knowledge about the sample and/or the conditions of analysis. Two types of prior knowledge were used to interpret spectra from a pure silicon sample as well as a NIST SRM 610 glass sample and alumina with a controlled Ni contamination at different concentrations. Knowledge of the elemental composition confirmed the existence of spectral lines with high sensitivity to interference while other lines are more appropriate for analysis due to their consistent SIFs despite having knowledge of the composition.

Laser-induced breakdown spectroscopy (LIBS) has recently demonstrated its unrivaled performance for broadband elemental imaging of surfaces. The dimensions of the laser sampling spot still being potentially larger than the interfaces of chemical domains, the plasma created at each location can be largely varying and inhomogeneous with contributions from the different sides of the interface. This variation can become problematic when imaging it on fiber bundles connected to multiple spectrometers. A spatially heterogeneous signal would lead to spatially dependent image on the fiber bundle causing inconsistent readings and loss of efficiency. Köhler illumination is used in this study to create a homogenous illumination, regardless of the source homogeneity, thus improving light collection efficiency. The performance of this approach was demonstrated with inhomogeneous spectral sources and applied to the LIBS analysis of a metallic interface, showing up to a sixfold improvement of the homogeneity of the plasma collection.

Forensic palynology has played a crucial role in many criminal investigations, from burglary to homicide, rape, war crimes, terrorism, and drug trafficking. With the emergence of DNA barcoding, pollen genomics has immense potential to classify and identify pollen taxonomically from its genetic signature. In forensic analysis, a non-destructive method for evidence is essential. Thus, several challenges exist for the extraction of DNA from the pollen grains, such as keeping the grain intact for secondary analysis and bypassing the issue of DNA mixtures more likely to be observed in a pollen assemblage. In this study, a new method was developed to address these challenges and was designed to extract genetic material while not destroying the pollen grain on a single grain level. We demonstrate the mehod's efficiency with Pinus echinata, Taxodium distichum, and Plantago lanceolata single pollen grains. Quantitative PCR amplification of two genetic markers, ribulose bisphosphate carboxylase (rbcL) and internal transcribed spacer 2 (ITS2), and digital microscopy demonstrates the non-destructive nature of this novel DNA extraction method from single pollen grains.

The effect of silica on the densification of transparent YAG ceramics has long been investigated. The present paper makes a step forward on the quantification of the Si amount in YAG. The study shows how to measure with a high level of accuracy the silicon concentration in YAG in different steps of the fabrication process. The Laser-Induced Breakdown Spectroscopy (LIBS) has been used to quantify the amount of silicon in a set of samples with 0–0.275 wt% silica. Nanometric silica soot or its precursor, TEOS, has been used as silica source. The analysis shows that more than 80 wt % of SiO2 evaporates during reactive-sintering under vacuum, most probably because SiO gas forms during sintering under low oxygen partial pressure. In-depth concentration maps were obtained by laser drilling with LIBS pulses. The results show the possibility to modify the amount of residual Si in YAG ceramics by adjusting the sintering and annealing process.

The quantification of silicon content during the reaction sintering preparation process was studied using Laser-Induced Breakdown Spectroscopy (LIBS). YAG ceramics with different additions of silica have been analyzed at different steps of the process, and a significant drop in silica content was observed after the vacuum sintering step, which can be attributed to evaporation. 1. Introduction It is well known that silica can be used as a sintering aid in yttrium aluminum garnet (YAG) ceramics, leading to transparency. This approach has been successfully used in the 1990s with colloidal silica and TEOS and has brought many interesting results since. However, even though there are various publications dealing with the effect of silica addition on the transparency and microstructure of YAG ceramics [1-4], the number of studies on the solubility of Si in YAG and the processes occurring during the ceramics production is limited. Recently, it was shown that Laser-Induced Breakdown Spectroscopy (LIBS) can be used for the quantitative determination of the variations in stoichiometry of YAG [5] and of the amount of silica [6]. The presentation shows an analysis of the amount and distribution of silicon in YAG ceramics at different steps of the production process using reactive sintering using Laser-Induced Breakdown Spectroscopy. Monitoring the Si content step by step provides important information about the reproducibility and consistency of the fabrication process, crucial for any further optimization. 2. Experimental A set of mixtures with different silicon content was prepared from oxide powders and TEOS or SiO2. The powders were mixed, granulated, pressed, treated in air, sintered under high vacuum and annealed in air. The silicon content was characterized by Laser-Induced Breakdown Spectroscopy (LIBS) at different steps of the preparation process, collecting data from multiple shots for each measurement (see Fig. 1). For selected samples, in-depth concentration maps were obtained. 3. Results After a calibration using stoichiometric mixtures of oxides, quantitative data for samples with the addition of TEOS ranging from 0 to 1 wt% were obtained. The obtained quantification limit was 0.0463 wt.% of SiO2 (216 ppm of Si). The most important change throughout the preparation process was observed with the vacuum sintering step, where a large part of silica left the material. A variation in the silicon content inside the samples was observed, with lower concentrations at the outer parts. 4. Conclusions The analysis of silicon content in YAG ceramics with different initial additions of silica provided a clear indication of a significant drop in silicon content after the vacuum sintering step, which can be attributed to evaporation. The presented results show that LIBS offers a user-friendly solution to a better understanding of the role and behavior of sintering additives in the processing of advanced ceramics. 5. References [1] Boulesteix R., Maître A., Baumard J.-F., Sallé C., Rabinovitch Y. Opt. Mater. 31 (2009) 711-715. [2] Stevenson A. J., Li X., Martinez M. A., Anderson J. A., Suchy D. L., Kupp E. R., Dickey E. C., Mueller K. T., Messing G. L., ,,Effect of SiO2 on densification and microstructure development in Nd:YAG Transparent Ceramics," J. Am. Ceram. Soc. 94 (2011) 1380-1387. [3] J. Hosta?a, L. Esposito, A. Piancastelli, "Influence of Yb and Si content on the sintering and phase changes of Yb:YAG laser ceramics," J. Eur. Ceram. Soc 32(11), 2949-2956 (2012). [4] R. Gaume., Y. He , A. Markosyan, R. L. Byer, "Effect of Si-induced defects on 1 µm absorption losses in laser-grade YAG ceramics," J. Appl. Phys. 111(9), 093104 1-5 (2012). [5] S. J. Pandey, M. Martinez, F. Pelascini, V. Motto-Ros, M. Baudelet, R. M. Gaume, "Quantification of non-stoichiometry in YAG ceramics using laser-induced breakdown spectroscopy," Opt. Mater. Express 7(2), 627-632 (2017). [6] S. J. Pandey, M. Martinez, J. Hosta?a, L. Esposito, M. Baudelet, R. Gaume, "Quantification of SiO2 sintering additive in YAG transparent ceramics by laser-induced breakdown spectroscopy (LIBS)," Opt. Mater. Express 7(5), 1666-1671 (2017). 5. Acknowledgements Romain Gaume wishes to thank the Air Force Office of Scientific Research for supporting his work under award number FA9550-18-1-0103.

The workflow for mature-field redevelopment requires a multidisciplinary team to analyze, select, and rank well candidates for intervention and production optimization. An objective evaluation of the well's productivity and reserves is essential for identifying possible alternatives to increase production. For this study, an analysis was conducted on 152 wells from the Carito field. As the second-largest oilfield producer in the Maturin sub-basin of eastern Venezuela, the Carito field encompasses approximately 150 km2 and comprises the El Carito and Carito south reservoirs. The Carito reservoir presents a high degree of heterogeneity resulting from complex, compressional faulting and varying sediments and includes hydrocarbons containing gas, condensate, volatile, black oils, and tar mat (oil mixed with wet sand). The Carito south reservoir behaves like a black-oil reservoir. The workflow presented in this study identified 20 candidate wells ranked by their potential to increase production. An intervention plan was then defined and ranked according to technical and economic criteria. This paper presents the successful application of this methodology in the Carito field to improve well productivity by approximately 7,000 bpd, proving that the method can be easily adapted to other areas.

Zinc is an element required in multiple biochemical processes in the human body as a structural, regulatory or catalytic ion. Its deficiency is linked to issues of a variety of health processes such as physical growth, immune system, or reproductive functions to name a few. Its quantitative determination using Laser-Induced Breakdown Spectroscopy (LIBS) on fingernails as a proxy has been proposed by many studies. In this study, a solid matrix-matched material was developed as a reference material for this type of analysis. A solution of alginic acid and keratin, spiked with zinc oxide nanoparticles, was cross-linked and dried to obtain a hard film. The calibration curve showed a determination coefficient of 0.986, Zn limit of detection of 13 μg.g−1 and limit of quantitation of 27 μg.g−1. The calibration curve was used on two toenails and the Zn concentration was confirmed by bulk ICP-MS. These results confirmed the potential for LIBS to be used for the quantitative diagnostic of Zn in fingernails using these adapted matrix-matched reference materials.

Laser ablation has become the most accepted method for direct sampling of solid materials, as in elemental trace analysis by laser-induced breakdown spectroscopy. However, the scarcity of matrix-matched standards or reference materials (such as NIST reference materials for instance) is an obstacle to quantitative analysis, particularly in the area of hard biological materials analysis, such as bones and teeth. If existing, the corresponding certified standards often consist of powders, then compacted as pellets which density, cohesive strength and dopant incorporation are not always representative of the samples under investigation, thereby casting serious uncertainties on calibration protocols. Here, we report on the synthesis of hydroxyapatite reference ceramic materials that can be doped controllably with various elements of interest. The fabrication process involves spiking during synthesis, prior to a hard sintering of pelletized ceramics. As a result, these materials have good chemical homogeneity and ablation properties that mimic those of naturally calcified biological tissues.

Transparent ceramics are important optical materials with applications in street lighting, high-strength windows, electro- and magneto-optical isolators, high-power laser gain media and radiation detectors. Their fabrication most often relies on powder densification techniques carried out at high temperatures, sometimes promoted by sintering additives. Here, we describe the application of laser-induced breakdown spectroscopy (LIBS) for following the concentration levels of silica used as a sintering agent in the fabrication of yttrium aluminum garnet (YAG) transparent ceramics. The sensitivity limit of our protocol reaches a few tens of ppm of silica in YAG ceramic samples, showing that LIBS can be implemented reliably for the rapid assessment of sintering additives in advanced ceramic processing.

Silica is typically used as a sintering aid in the production of transparent YAG (Y3Al5O12) ceramics, allowing for the achievement of nearly pore-free microstructures and the lowering of sintering temperatures. However, it was also found to introduce undesired color centers in the sintered material [1] as well as segregate at grain boundaries leading to the formation of amorphous or crystalline secondary phases (Y2SiO5) [2], which decrease the optical properties and compromise the use of the material as a laser medium. Thus, while the addition of silicon (in the form of SiO2 or as tetraethyl orthosilicate, TEOS) is often required, it is desirable to obtain materials with low Si content and homogeneous distribution. This work studies the amount of Si and its distribution in YAG and Yb:YAG ceramic materials produced by reaction sintering of a mixture of oxide powders throughout the whole preparation process. Monitoring the Si content step by step provides important information about the reproducibility and consistency of the fabrication process, crucial for any further optimization. We have shown that Laser-Induced Breakdown Spectroscopy (LIBS) allows sensitive and accurate quantification of silicon in ceramics down to 60 ppm and our experimental LIBS setup was used to analyze the evolution of the silicon content in samples at various steps of the fabrication process [3]. The distribution of Si in sintered ceramics was studied with High Resolution TEM to detect any possible nano-precipitates, and EDX nano-probe chemical analysis to check for segregation at grain boundaries and evaluate Si concentration within the YAG grains. The amount of Si present in the sintered materials has been found to be as low as 30 % of that introduced into the initial mixture. References 1. R. Gaume, Y. He, A. Markosyan and R.L. Byer, "Effect of Si-induced defects on 1 µm absorption losses in laser-grade YAG ceramics", J. Appl. Phys., 111, pp.093104, 2012 2. L. Esposito, T. Epicier, M. Serantoni, A. Piancastelli, D. Alderighi, A. Pirri, G. Toci, M. Vannini, S. Anghel and G. Boulon, "Integrated analysis of non-linear loss mechanisms in Yb:YAG ceramics for laser applications", J. Eur. Ceram. Soc., 32, pp.2273-2281, 2012 3. S.J. Pandey, M. Martinez, J. Hosta?a, L. Esposito, M. Baudelet and R. Gaume, "Quantification of SiO2 sintering additive in YAG transparent ceramics by Laser-Induced Breakdown Spectroscopy (LIBS)", Opt. Mater. Express (submitted)

Well tests are typically used to evaluate formation damage before and after workovers. Buildup tests are the most commonly used transient because less flow rate measurement uncertainties leading in more reliable results, and they have a robust mathematical foundation. To take in account the flow rate history and its uncertainties several deconvolution algorithms were developed. These algorithms also are applicable to minimize the initial distortion in the reservoir's pressure response due to wellbore storage, with the expectation of improving the permeability and total skin estimated in shorter logging times.This paper presents a comparative study of conventional well test methods, and direct and indirect deconvolution techniques in several field cases. This study includes buildup tests of real-time sandface rate measurements during the after-flow period. These field cases were analyzed using conventional well test methods and three deconvolution techniques; namely, straight line approximation, material balance deconvolution, and modified "β" function.We determined that the three deconvolution methods are preferable to conventional well test methods because they require much shorter logging times; however, their reliability depends on the real-time data acquisition quality.The well tests analyzed show that we cannot rely solely on the new deconvolution techniques for well test interpretation in shorter times; however, these new methods improve the reliability in the main matching parameters, permeability and total skin, at no additional time and cost. As a result, the new methods are excellent additions to the techniques used for well test interpretation.

International audience; A coupling of thin layer chromatography with laser ablation ICP SF MS was developed for the fractionation of Ni, V, Fe and S in crude oil and its fractions (saturate, aromatic, resin and asphaltene). The detection limits were 18 ng g -1 and 23 ng g -1 for nickel and vanadium, respectively, and a sample could be characterized in terms of the metal distribution as a function of species polarity within 10 min. The method was used to characterize the metal distribution in crude oils of different origins and their different fractions. © 2012 Elsevier B.V. All rights reserved.

Transparent ceramics are important optical materials with applications in street lightning, high-strength windows, electro- and magneto-optical isolators, high-power laser gain media and radiation detectors. Their fabrication most often relies on powder densification techniques carried out at high temperatures and promoted by dopants, so-called 'sintering additives'. The monitoring of sintering additive concentration, throughout the fabrication process of ceramics, is particularly important in optimizing their effect and maintaining high optical quality and consistency in these materials. Here, we describe the use of Laser-Induced Breakdown Spectroscopy (LIBS) for following the evolution of the concentration levels of silicon in the fabrication of YAG transparent ceramics, a well-known laser material. We have developed an adequate experimental protocol to measured silicon doping in the range of a few hundreds of ppm in test ceramic samples of YAG, and built a calibration curve to quantify it. These results show that LIBS can be reliably implemented for quick assessment of sintering aids in advanced ceramic processing. This work has been funded by the National Institute of Justice and the State of Florida.

International audience; Encapsulation of samples in Zr xerogels has been implemented for the elemental analysis of crude oils using laser-induced breakdown spectroscopy. Pellets produced from xerogels proved to be durable and homogeneous, and they allow for ablation of the samples without splatters. Ni and V present in Venezuelan crude oil were used as probe elements, and Yttrium was used as an internal standard to take into account the fluctuations in the amount of ablated material. All of the calibration curves obtained were described by high correlation coefficients, r2 \textgreater 0.990. Detection limits of 7 and 4 μg g-1 for V and Ni were estimated, respectively. V/(V + Ni) quotients showed high values of \textgreater0.8. The accuracy of the method was assessed by analyzing standard reference materials (SRM 1084a and 1085b). The measured values of V and Ni in the SRM agreed well with the certified values at the 95% confidence level. © 2015 American Chemical Society.

One of the most important diseases in cereal crops is Fusarium head blight, being Fusarium graminearum the main etiological agent. This fungus has the ability to produce a wide spectrum and quantity of toxins, especially deoxynivalenol (DON). During the last crop season (2012-2013) the climatic conditions favored Fusarium colonization. The objective of this work was to determine the presence of this fungus as well as the DON content in 50 wheat grain samples. Our results showed that 80% of the samples were contaminated with Fusarium graminearum. Twenty four percent (24%) of the samples contained ≥ 1μg/g DON, 26% ranged from 0,5 and 0,99μg/g, and the remaining 50% had values lower than 0,5μg/g. Correlation was found between the presence of Fusarium graminearum and DON. It is necessary to establish DON limit values in wheat grains for human consumption.

International audience; Strict control of composition is of paramount importance for the reproducible fabrication of advanced ceramics. In particular, the preparation of high-grade transparent ceramics of definite line-compounds requires that the ratio of major constitutive elements be quantified with a precision better than a fraction of a mole percent to prevent the precipitation of secondary phases and the scattering of light. Such a requirement poses difficult challenges to most analytical methods, especially when applied to nearly-stoichiometric insulating phases. In this work, we show that laser-induced breakdown spectroscopy (LIBS) is a well-suited technique for the assessment of non-stoichiometry in yttrium aluminum garnet (YAG) ceramics and that the aluminum to yttrium ratio can be determined with a resolution of 0.3 mol %, well within the phase boundaries of YAG.

International audience; A novel method for the preparation of crude oil samples based on a xerogel matrix was developed for elemental analysis using laser ablation-double focusing sector field inductively coupled plasma-mass spectrometry. The samples and aqueous solution were successfully encapsulated using zirconium n-propoxide. The use of xerogel produces stable and homogeneous pellets, avoids splashing of the sample and allows the use of aqueous inorganic standards to elaborate the calibration curve. Sulfur, nickel and vanadium were selected as test elements and indium was used as the internal standard to correct the variations in the amount of material ablated. The correlation coefficients of the calibration curves for all the elements tested were better than 0.990 except for sulfur. Crude oil results showed no significant statistical differences between the sol-gel results and those obtained with similar studies. © 2012 The Royal Society of Chemistry.

Biochemical analysis and clinical tests like glucose, hemoglobin, cholesterol, iron, etc. are crucial for early illness diagnosis like diabetes, anemia and coronary deceases. These tests usually are done in state of the art instruments in well equipped laboratories in health centers. In some cases, these instruments are not portable, so they are not recommended for clinical field studies in remote areas. The present work shows a portable low-cost prototype of multi-well plates reader designed for clinical analysis. A Light Emission Diodes (LEDs) array is used as excitation source and an inexpensive webcam as detector. The light source illuminates the 96 well plates and the webcam take the image with 640x480 pixels. The data is acquired and processed by using a portable computer. 96 samples can be read including blanks and calibration standards simultaneously. Light absorption data are processed using a MatLab software designed in our laboratory to obtain calibration curves, standards lectures and samples concentration. The system was evaluated using different analytes series solutions: Neutral Red, Cooper (II) Ammonia Complex and Methyl Orange. The results shows that it is possible to measure few micro liters of solutions with adequate exactitude and precision of less than 3%. As possible analytical clinical application, iron determination was performed using Fe(III) Thiocyanate complex. This method is usually applied in serum samples analysis. The sensibility achieved with the proposed instrumentation configurations allows the analysis of iron in serum samples in the references values normal range (0.75 - 1.5 mg/L) in human.