•We evaluated the uncertainty in mass measurements of four electronic configurations in lysimeter.•Uncertainty in excitation and acquisition by datalogger increase the system general ...uncertainty.•Periodic calibrations are necessary to compensate systematic errors due the damage by use.•Only regression analysis is not sufficient to evaluate weighing lysimeters.•Errors and uncertainties were attenuate due the use of indicator module in the Measurement System.
The determination of measurement reliability in weighing lysimeters via error analysis is essential for scientific research and irrigation management. The objective of this study was to evaluate four different weight measuring systems (MSs) applied to load cell weighing lysimeters and compare the results with the expected uncertainty values obtained from data provided by manufacturers. A weighing lysimeter with an area of 0.385 m2 and a volume of 0.289 m3 was used, installed on three load cells. In MS1, the load cells were connected to a junction box and the box to a weighing indicator module in a six-wire configuration. In MS2, a four-wire connection was used between the junction box and a datalogger, whereas in MS3, there was a six-wire connection. For MS4, the connection between the load cells and datalogger was direct. The uncertainties of the measurement systems were determined from the calibration results. MS1 presented the lowest measurement errors and uncertainties, resulting in performance superior to those of the other MSs. After MS1, the best performances were obtained by MS2 and MS3, and MS4 presented the worst performance. The effect of the signal measurement uncertainties and the excitation by the datalogger had the greatest effects on the overall uncertainty of the system compared with the influence of temperature on the load cells. The measurement system may be selected according to the technical data supplied by the manufacturer; however, periodic calibration of the effective measuring range is necessary to verify and compensate for systematic errors, which are accentuated during the operation time.
Pharmaceutical cocrystals are mixed crystals that contain two or more different molecular components. These crystals usually present different characteristics from their precursor, an improvement in ...the drug solubility being the most important property. This article is the first to report a green synthesis of ibuprofen–nicotinamide cocrystal in aqueous media. The use of safer solvents and in-line monitoring are some of the green chemistry principles that should be evaluated in environmentally correct synthesis. The Raman spectroscopy as a PAT tool provided an effective in line method to monitor and quantify the reaction. This is the first report of the cocrystal of ibuprofen–nicotinamide obtained by slurry conversion. A total conversion of the initial substrates into the cocrystal was obtained in mild conditions. The use of chemometric tools and Raman spectroscopy made it possible to monitor and understand the cocrystallization mechanism, and the synthesis provided.
Classification systems are frequently used in tobacco Green Leaf Threshing (GLT) facilities to assess the chemical characteristics and quality of tobacco leaves. This classification is usually ...performed by a trained specialist who has to analyse and classify the leaf, in a short time, based on experience and visual information. However, this approach is not robust and may be biased due to its highly subjective nature. This work proposes the use of infrared hyperspectral imaging and chemometric tools for discriminant analysis. A fast and real-time method to classify flue-cured Virginia and air-cured Burley tobacco was developed by classifying the leaf based on three criteria: (a) stalk position, (b) leaf colour, and (c) leaf quality; this occurs within 5 seconds. The applicability of the method was evaluated by analysing standard tobacco leaf bundles using near-infrared imaging and Support Vector Machine-Discriminant Analysis (SVM-DA). The models classified the stalk position with a global prediction accuracy of 80.4% for flue-cured Virginia and 88.1% for air-cured Burley. The models for targeting leaf classification by colour presented a global prediction accuracy of 95.9% for flue-cured Virginia and 96.5% for air-cured Burley. For leaf quality, the prediction accuracy ranged from 61.5% to 100.0% for flue-cured Virginia and 78.8% to 100.0% for air-cured Burley. The system was implemented in a tobacco GLT facility for one year to cover an entire crop season and extended to include tobacco bales and leaf bundles. For the most complex classification parameter, leaf quality, flue-cured Virginia models presented a global accuracy of 50.2% to 71.6%. Considering the high complexity of the system and short period of analysis, the obtained accuracy was accepted as suitable when compared to traditional human classification.
A cocrystallization process may involve several molecular species, which are generally solid under ambient conditions. Thus, accurate monitoring of different components that might appear during the ...reaction is necessary, as well as quantification of the final product. This work reports for the first time the synthesis of carbamazepine-nicotinamide cocrystal in aqueous media with a full conversion. The reactions were monitored by Raman spectroscopy coupled with Multivariate Curve Resolution - Alternating Least Squares, and the quantification of the final product among its coformers was performed using Raman spectroscopy and Partial Least Squares regression. The slurry reaction was made in four different conditions: room temperature, 40°C, 60°C and 80°C. The slurry reaction at 80°C enabled a full conversion of initial substrates into the cocrystal form, using water as solvent for a greener method. The employment of MCR-ALS coupled with Raman spectroscopy enabled to observe the main steps of the reactions, such as drug dissolution, nucleation and crystallization of the cocrystal. The PLS models gave mean errors of cross validation around 2.0 (% wt/wt), and errors of validation between 2.5 and 8.2 (% wt/wt) for all components. These were good results since the spectra of cocrystals and the physical mixture of the coformers present some similar peaks.
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•Pure cocrystal bulk was obtained by synthesis in water at 80°C.•Raman spectroscopy and MCR-ALS were employed for in-line monitoring.•The drug dissolution, nucleation and crystallization steps were identified by Raman.•PLS regression models allowed the quantification of cocrystal among its precursors.•The quantification models presented RMSEV between 2.5 and 8.2% for all components.
Euschistus heros (Hemiptera: Pentatomidae) has two allopatric strains with a hybrid zone in central Brazil. Asymmetric dispersal and gene flow between these strains of E. heros have been observed, ...where the South strain (SS) moves more quickly to the northern regions of the country than the North strain (NS) to the southern areas. In addition, SS generally has a bigger body size and presents dark brown coloration, and NS is usually smaller in size and presents light brown coloration. Here, we studied the reproductive behavior and tested for the presence of assortative mating and reproductive barriers between the two allopatric strains of E. heros. Nonrandom mating was observed in the SS strain based on mating choice trials and the reproductive isolation indexes. SS females and males prefer to mate with their co-specific (same strain) partner, while NS insects showed no mating preference. The insect's pronotum width was positively associated with the mating choice suggesting size-assortative mating in E. heros. Reciprocal crosses between strains yielded similar reproductive outputs when compared with pure strain crosses, suggesting similar fitness of hybrid pure strains. The asymmetric gene flow in the hybridization zone that favors SS seems to be associated with the reproductive behavior of the species, which favors the typical phenotype found in the SS populations.
The most common COVID-19 testing relies on the use of nasopharyngeal swabs. However, this sampling step is very uncomfortable and is one of the biggest challenges regarding population testing. In the ...present study, the use of saliva as an alternative sample for COVID-19 diagnosis was investigated. Therefore, high-resolution mass spectrometry analysis and chemometric approaches were applied to salivary lipid extracts. Two data organizations were used: classical MS data and pseudo-MS image datasets. The latter transformed MS data into pseudo-images, simplifying data interpretation. Classification models achieved high accuracy, with pseudo-MS image data performing exceptionally well. PLS-DA with OPSDA successfully separated COVID-19 and healthy groups, serving as a potential diagnostic tool. The most important lipids for COVID-19 classification were elucidated and include sphingolipids, ceramides, phospholipids, and glycerolipids. These lipids play a crucial role in viral replication and the inflammatory response. While pseudo-MS image data excelled in classification, it lacked the ability to annotate important variables, which was performed using classical MS data. These findings have the potential to improve clinical diagnosis using rapid, non-invasive testing methods and accurate high-volume results.
•Activated charcoal (AC) is a low cost alternative material for electroanalysis.•A robust modified electrode is developed by immobilizing gold nanoparticle-decorated activated charcoal (AuNPs-AC) ...film.•A Doehlert matrix design experiment is used to optimize the electrode performance.•The AuNPs-AC based sensor presents enhanced response toward an antiparkinsonian drug sensing•The voltammetric method was successfully applied for levodopa determination in biological and environmental samples.
Levodopa analysis is important to monitor progress of patients in Parkinson's disease, as well as to determine the treatment directions. In this way, the development of an electrochemical sensor based on a glassy carbon electrode modified with gold nanoparticles supported in activated charcoal with an epichlorohydrin-reticulated chitosan film was carried out under the assistance of a Doehlert matrix design experiment. The resulting electrode was subjected to a series of characterization techniques, including scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, for morphological analysis, as well as electrochemical impedance spectroscopy and cyclic voltammetry for electrochemical characterization. The active surface presented response for electrocatalytic oxidation of levodopa with high current response at reduced potential, which was applied, along with a square-wave adsorptive anodic stripping voltammetric methodology, for analysis of levodopa in different samples, presenting a three order of magnitude linear concentration range (50.0 nmol L−1 to 10.0 µmol L−1), low detection limit of 8.2 nmol L−1, good recovery analysis of spiked samples with low signal deviation under the presence of interfering species, and good accuracy front a comparative methodology.
Schematic representation of experimental steps followed for determination of levodopa levels in pre-therapeutic phase of Parkinson`s disease by a square-wave adsorptive anodic stripping voltammetric method. Display omitted
Diagnosis of cancer using electroanalytical methods can be achieved at low cost and in rapid assays, but this may require the combination with data treatment for determining biomarkers in real ...samples. In this paper, we report an immunomagnetic nanoparticle-based microfluidic sensor (INμ-SPCE) for the amperometric detection of the prostate-specific antigen (PSA) biomarker, the data of which were treated with information visualization methods. The INμ-SPCE consists of eight working electrodes, reference and counter electrodes. On the working electrodes, magnetic nanoparticles with secondary antibodies with the enzyme horseradish peroxidase were immobilized for the indirect detection of PSA in a sandwich-type procedure. Under optimal conditions, the immunosensor could operate within a wide range from 12.5 to 1111 fg·L
−1
, with a low detection limit of 0.062 fg·L
−1
. Multidimensional projections combined with feature selection allowed for the distinction of cell lysates with different levels of PSA, in agreement with results from the traditional enzyme-linked immunosorbent assay. The approaches for immunoassays and data processing are generic, and therefore the strategies described here may provide a simple platform for clinical diagnosis of cancers and other types of diseases.
ABSTRACT Among the various forage species used in ruminant feeding, elephant grass (Pennisetum purpureum Schum.) is notable as it is a perennial plant and has a high potential for dry matter ...production. The present study evaluated the performance of elephant grass cultivars and soil chemical characteristics under different biochar addition levels and at different evaluation times under irrigation in the dry season. The treatments were arranged in a factorial randomized complete block design (CBD) and analyzed in a split-plot design according to cultivar (BRS Capiaçu and BRS Kurumi) x biochar dose (0, 8, 16 and 24 t ha-1); the subplots consisted of four evaluation times (71, 225, 335 and 447 days after application of biochar), with four replicates. The soil chemical characteristics were evaluated without inclusion of the time factor according to a CBD in a 2 x 4 factorial scheme, with 4 replications. The attributes analyzed were soil fertility, morphometry and elephant grass yield. The performance of the cultivars improved at 225 days (2nd evaluation) and 335 days (3rd evaluation) after biochar application. The biochar doses did not significantly increase morphometric attributes, cultivar productivity or soil fertility. The application of biochar did not improve the yield attributes or crude protein of elephant grass cultivars under the conditions of this study.
RESUMO Entre as diversas espécies forrageiras utilizadas na alimentação de ruminantes, o capim elefante (Pennisetum purpureum Schum.) se destaca por ser perene e de elevado potencial de produção de matéria seca. Objetivou-se com o presente trabalho avaliar o desempenho de cultivares de capim elefante e características químicas do solo sob diferentes níveis de biochar e épocas de avaliação sob irrigação na época da seca. Os tratamentos foram dispostos em delineamento em blocos casualizados (DBC) em esquema fatorial, e analisado em parcelas subdivididas, sendo as parcelas, as cultivares BRS Capiaçu e BRS Kurumi x doses de biochar (0, 8, 16 e 24 t ha-1), e as subparcelas, quatro épocas de avaliação (71, 225, 335 e 447 dias após aplicação do biochar), com quatro repetições. Para avaliação de características químicas do solo o delineamento não teve o fator épocas, sendo analisado em DBC em fatorial 2 x 4, com 4 repetições. Os atributos analisados foram a fertilidade de solo, a morfometria e o rendimento de capim elefante. Nas avaliações aos 225 (2ª) e 335 (3ª) dias após aplicação de biochar houve melhor desempenho das cultivares. As doses de biochar não aumentaram significativamente atributos morfométricos, de produtividade das cultivares e fertilidade do solo. A aplicação de biochar não melhora os atributos de produtividade e proteína bruta das cultivares de capim elefante nas condições deste estudo.
Tobacco-specific nitrosamines (TSNAs), mainly the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are known carcinogens. Part of the NNK found in smoke is provided from matrix-bound NNK, and ...its determination is extremely relevant. However, the reference extraction procedure of matrix-bound NNK is time-consuming and labor-intensive and has a limited analytical capacity. Three different methodologies were proposed to predict matrix-bound NNK: simple linear regression (LR) with soluble NNK; multiple linear regression (MLR) considering soluble NNK and characteristic parameters of the samples; and orthogonal partial least-squares (O-PLS) regression using high-throughput screening by flow injection analysis coupled to high-resolution mass spectrometry (HTS-FIA-HRMS) data. Simple linear regression showed a high influence of matrix and leaf origin. Although an existing linearity trend has been observed (R 2 = 0.62) for the global model, higher correlation values were achieved for matrix and country segregation models. Multiple linear regression predicted matrix-bound NNK with more satisfactory efficiency than simple linear regression models. The coefficients of determination were 0.87 and 0.94 for flue-cured Virginia and air-cured Burley, respectively. However, this method has a limited application, since previous information about the sample is required. The proposed method based on HTS-FIA-HRMS and O-PLS has shown the most suitable performance in the prediction of matrix-bound NNK, with errors comparable to the reference method, and a higher throughput. In addition, this approach allows to determine other soluble nitrosamines, namely N′-nitrosoanatabine, N′-nitrosoanabasine, and N-nitrosonornicotine, with relative percentage errors between 5.25 and 11.98%. Therefore, the third approach is the best method for a large number of cured tobacco for accuracy in determination of TSNAs.
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