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Antioxidants are molecules that act against free radicals, and this effect can bring many benefits to health and society. Antioxidants can be found in various matrices of nature, such as fruits and plants. Some studies have shown that "Rhizophora mangle," a typical mangrove plant, is rich in antioxidants. People report its use for medicinal purposes, such as treating diabetes and high blood pressure. In Espírito Santo, Brazil, the bark extract of the plant is used as a waterproofing agent in the making of the capixaba clay pan, a cultural symbol of the state. Thus, this context was used as a reference for the application of chemical knowledge addressed in the teaching of Instrumental Analytical Chemistry. The participants were undergraduate chemistry students at the Federal University of Espírito Santo (Ufes). Two experiments were designed to be performed by groups of four to five students during 2-4 h laboratory classes. The students employed analytical techniques for spectrophotometric (FRAP, ferric reducing antioxidant power) and electrochemistry (CRAC, ceric reducing antioxidant capacity) determination of the total antioxidant capacity of "R. mangle" bark extracts. The experimental results indicated that the extracts of the plant have significant antioxidant capacity compared to trolox. By performing different extraction procedures and analytical techniques, students were able to compare, analyze, and evaluate strategies aimed at determining antioxidant capacity. The antioxidant capacity assays can be expanded to analyze other matrices of interest to professors and students.

Harmful plastic debris found on beaches and in the oceans are not limited to drinking straws or bags. There are several synthetic organic polymers that can be used to make different kinds of plastic materials and have resulted in billions of tons of waste that can reach the aquatic biome and are harmful to freshwater and marine communities as well as humans. Small pieces, known as microplastics, are very small (<5mm) and can readily be ingested by marine organisms, causing dangerous threats to the food supply chain. Although plastic debris appears as particles of varying size, shape, color, and chemical composition, its origin or source cannot easy be identified by the naked eye. Sometimes, it is also difficult to identify whether debris is made of plastics materials. However, plastic debris sources can be revealed by applying basic concepts of the interaction of infrared radiation with matter. If a sample is irradiated with infrared light, a part of the radiation can be absorbed and provide detailed information about the structure of chemical compounds, such as the arrangement of nuclei and chemical bonds within the molecule. Chemical features of a molecule allow identification of the type of polymer that makes up a plastic material. In this paper the authors describe a multidisciplinary approach to teaching the interaction of infrared light and the vibrating process of molecules to characterize plastic pollutants. The practical classes involve both indoor and outdoor activities, divided into four steps: choice of case study site; plastic debris sampling; sample preparation and physical and chemical characterization of plastic debris (size, color, shape and polymer type); data interpretation and identification of the main plastic debris sources. The first three steps, which include outdoor activities, can also be performed by students of all ages, as well as by geography, environmental science and biology teachers who are fundamental in multidisciplinary studies. The data interpretation step that involves the polymer identification is performed at the laboratory, by using ATR-FTIR and/or optical transmittance sensor systems. Finally, the identification of the main plastic debris sources and the final conclusions are tasks that can be performed in a multidisciplinary way.

This experiment describes a simple protocol for teaching acid-base titrations using potentiometry, conductivity, and/or photometry to determine end points without an added indicator. The chosen example examines the titratable acidity of a red wine with NaOH. Wines contain anthocyanins, the colors of which change with pH. Importantly, at the equivalence point, anthocyanins maintain their color, and this effect can be captured optically using a desktop scanner. RGB-based color values are obtained from the digitized images using a dedicated application and employed to generate plots of |v| versus titrant volume. The end point is the point at which the slope (d|v|/?/dV) of the titration curve is at a maximum; (d|v| is a vector expression of the color change). The photometric titrations were carried out using a plastic 96-well immunology plate and a flat-bed scanner, and RGB values were extracted simultaneously from all 96 wells in less than 5 min from the images using the ImageJ plugin "ReadPlate". The wine was also titrated using conventional potentiometric and conductometric techniques, and methods were compared using F-test, "t"-test, and one-way ANOVA. The potentiometric titration yields pH versus titrant volume curves, and the equivalence point is where the slope, or the slope of the derivative curve (dpH/dV), is greatest. The conductometric titration yields conductivity versus titrant volume curves, and the end point is determined as the volume where the slope exhibits a marked change. All titration and derivative curves were plotted and analyzed using spreadsheet software.

The continuing fascination of young people with celestial bodies leads them to pose challenging questions to their science teachers, such as how was the universe born? How were the stars formed? In this paper we present an extremely inexpensive but highly engaging activity to teach the basics of spectroscopy. Guided by the question "how do scientists know what a star is made of?", this simple activity allows a wide range of physical content to be taught, based on the analysis of the emission spectrum of a star's light. It is possible to see the configuration of lines of each chemical element as a fingerprint, thereby inferring each one's presence in the composition of the celestial body. As many countries do not have access to even inexpensive technologies, such as simple computers or digital cameras, this alternative could teach and motivate students of different ages to understand and enjoy the beauty of the nature of light.

The substitution of petroleum-based fuels with those from renewable sources has gained momentum worldwide. A UV-vis experiment for the quantitative analysis of biofuels (bioethanol or biodiesel) in (petroleum-based) diesel oil has been developed. Before the experiment, students were given a quiz on biofuels, and then they were asked to suggest a suitable UV-vis experiment for the quantification of biofuels in diesel oil. After discussing the results of the quiz, the experiment was conducted. This included the determination of [lambda][subscript max] of the medium-dependent, that is, solvatochromic, visible absorption band of the probe 2,6-bis[4-("tert"-butyl)phenyl]-4-{2,4,6-tris[4-("tert"-butyl)phenyl]pyridinium-1-yl}phenolate as a function of fuel composition. The students appreciated that the subject was linked to a daily situation and that they were asked to suggest the experiment. This experiment served to introduce the phenomena of solvation and solvatochromism. (Contains 6 figures.)

The present article describes some activities performed with high-school students in the "Solar Physics" course developed in a Brazilian science centre. The topics of chemical composition, temperature and stellar evolution were taught in a room totally dedicated to study of the Sun, a solar room, designed with simple and inexpensive equipment. The course strongly emphasized practical, observational and enquiry-based activities, such as estimating the solar surface temperature, observation of the visible solar spectrum, identification of solar absorption lines, and understanding how they are produced and what kind of information can be extracted from the observed spectral lines. Some of the course goals were to foster the comprehension of the key role played by spectroscopy in astrophysics, to contextualize contents with practical activities, and to allow interdisciplinary approaches including modern physics and chemistry in physics teaching. (Contains 6 figures.)

The mining and metallurgical industry sector activities often release potential toxic elements (PTE) surrounding exploitation area. We evaluated the addition of phosphate and lime using the dosage of 0.5:1, 1:1, and 2:1 molar ratio of PO43− and CO32− to the sum of PTE, respectively, and also, biochar and biosolids using the dosage of 2.5, 5, and 10% (m:m) to immobilize PTE in contaminated forest soil (Pb (270 mg kg−1) and Zn (858 mg kg−1)) near an abandoned mine site in Brazil. The desorption by stirred flow kinetics revealed that 15% of the total Zn and 12% Pb contents are mobile before any amendment application. Phosphate amendment decreased Pb desorption but increased Zn desorption. Biochar and biosolids immobilize high amounts of Zn and Pb because of their high cation exchange capacities and alkaline properties; however, 20% biosolid dose increased Pb desorption. X-ray absorption spectroscopy suggested Zn-kerolite as the major species in the contaminated soil, likely from mine dust. The change in Zn speciation after soil amendment addition indicated that biochar and lime kept a high proportion of Zn-Al species, whereas phosphate and biosolids led to more Zn-Fe species. Our results pointed out that lime might reduce both Pb and Zn mobilities; however, field trials are crucial to confirm the immobilization efficiency of lime and other amendments over long term. [ABSTRACT FROM AUTHOR]

Native to Brazil, Schinopsisbrasiliensis Engl. (Anacardiaceae) is the main representative species of the Schinopsis genus. It brings anti-inflammatory, analgesic, hemostatic, antiseptic, antibacterial, and antifungal properties. The aims of this study were to evaluate the antifungal potential of S.brasiliensis extract (API) against strains of Candidaalbicans, to perform a compatibility study with mucoadhesive excipients, to evaluate antifungal activity, and characterize a mucoadhesive hydrogel for oral use. The antifungal activity was evaluated, and a pharmacological potency assay of different concentrations of the hydroethanolic extract of the leaves of S.brasiliensis was performed using agar diffusion techniques, in a 5 × 1 cylinder design method. The compatibility study between binary mixtures (BM) of extract and excipients was performed using differential thermal analysis (DTA), thermogravimetry (TG), and Fourier transform infrared spectroscopy (FTIR). The hydrogels formulated were characterized for pH, viscosity, and mucoadhesive strength and then evaluated for antifungal activity. C.albicans was susceptible to the API at concentrations of 5, 10, 20, 40, and 80 mg mL−1. The pharmacological potency was superior than the gallic acid chemical marker, with the API concentration for the hydrogel formulation at 50 mg mL−1. The TG and DTA curves for the API—BM with carbopol (CAR) or pluronic hydrogel (PLU) maintained both the excipient and API thermal characteristics, suggesting compatibility between them. The 30% PLU hydrogel/API association presented the best performance and, considering the parameters of this study, should be further investigated as a potential oral antifungal agent with activity against C.albicans. [ABSTRACT FROM AUTHOR]

Purpose: Soil erosion by water yields sediment to surface reservoirs, reducing their storage capacities, changing their geometry, and degrading water quality. Sediment reuse, i.e., fertilization of agricultural soils with the nutrient-enriched sediment from reservoirs, has been proposed as a recovery strategy. However, the sediment needs to meet certain criteria. In this study, we characterize sediments from the densely dammed semiarid Northeast Brazil by VNIR-SWIR spectroscopy and assess the effect of spectral resolution and spatial scale on the accuracy of N, P, K, C, electrical conductivity, and clay prediction models. Methods: Sediment was collected in 10 empty reservoirs, and physical and chemical laboratory analyses as well as spectral measurements were performed. The spectra, initially measured at 1 nm spectral resolution, were resampled to 5 and 10 nm, and samples were analysed for both high and low spectral resolution at three spatial scales, namely (1) reservoir, (2) catchment, and (3) regional scale. Results: Partial least square regressions performed from good to very good in the prediction of clay and electrical conductivity from reservoir (< 40 km2) to regional (82,500 km2) scales. Models for C and N performed satisfactorily at the reservoir scale, but degraded to unsatisfactory at the other scales. Models for P and K were more unstable and performed from unsatisfactorily to satisfactorily at all scales. Coarsening spectral resolution by up to 10 nm only slightly degrades the models' performance, indicating the potential of characterizing sediment from spectral data captured at lower resolutions, such as by hyperspectral satellite sensors. Conclusion: By reducing the costly and time-consuming laboratory analyses, the method helps to promote the sediment reuse as a practice of soil and water conservation. [ABSTRACT FROM AUTHOR]

The ability of soil to sequester carbon and reduce atmospheric CO 2 concentrations is limited and depends on the soil minerals and their interaction with the microbiota. Microbial activities are closely associated with the types and amounts of soil organic matter (SOM) and clay minerals that have functional groups that interact with energy in Vis NIR-SWIR and Mid-IR wavelengths. The main objective of this research was to determine, based on these spectral ranges, the relation between mineralogical and organic compounds, as their sequestration and specialization in soils from Brazil. It was possible to map microbiological activity by spectral transfer functions and digital soil mapping reaching R 2 from 0.77 to 0.85. Multiple regression equations were constructed to quantify enzymatic activity, microbial biomass carbon (MBC), particulate organic matter (POM), and resistant forms of carbon, and SOM associated with the mineral fraction (MAOM). All these properties were detected by specific bands obtained with the recursive feature elimination (RFE) algorithm, reaching correlations from 0.64 to 0.98 in specific ranges. The prediction model of the carbon sequestration potential was adjusted with microbiological and mineralogical variables from Vis-NIR-SWIR and the Mid-IR spectral range. A SARAR double autoregressive model was adjusted with r 0.61 and to a spatial error model (SEM) with r 0.7. The explanatory variables were associated with kaolinite, hematite, goethite, gibbsite, and the abundance of fungi, actinomycetes, vesico-arbuscular mycorrhizal fungi, enzymatic activity of beta-glucosidase, urease and phosphatase, and POM. Among the microbiological variables, the general abundance of fungi was the most important, in contrast to enzymatic activity that was the least important. The interaction between the different maps constructed and historical land use allowed the identification of areas that contribute to sequestering new carbon and could be the key to climate change mitigation strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This review explores the historical, botanical, sensory, and quality aspects of Coffea canephora, with a focus on Brazil's rise as a producer of specialty canephora coffees in the Amazon region, Espírito Santo, and Bahia. Brazil has gained global recognition through the first geographical indications for canephora: Matas de Rondônia for robusta amazônico coffee and Espírito Santo for conilon coffee. Despite this, comprehensive insights into how variety, terroir, environmental conditions, and cultivation practices influence the chemical and sensory attributes of Brazilian canephora remain underdeveloped compared to well-studied arabica coffee. Producers and researchers are working to elevate canephora coffees to higher market levels, despite technological, production, and perception challenges stemming from its historical reputation for poor quality. Ensuring the sustainability of Amazonian canephora coffee without deforestation is particularly challenging due to the need to verify practices across numerous small-scale farms. There is also a critical need for standardized production and tasting protocols for Brazilian canephora, leveraging local expertise and professional cuppers to ensure consistent quality and reliable sustainability claims. Significant opportunities exist in valuing the production chain of geographically unique canephora coffees, which could increase specialty exports, enhance economic prospects for local farmers, and support Amazon preservation. Recognizing and marketing these coffees as premium products with unique flavor profiles can boost their global appeal. Another challenge lies in establishing new specialty standards for soluble coffee from specialty canephora to meet consumer demands for convenience without compromising taste or ethical standards. In such a scenario, several analytical methods have been suggested to identify high-quality variants, combating their stigmatization. The potential of spectroscopy techniques and chemometrics-based data science is highlighted in confirming coffee quality, authenticity, traceability, and geographical origin, enhancing model interpretation and predictive accuracy through synergistic and complementary information. Non-targeted spectroscopic analyses, providing comprehensive spectral fingerprints, are contrasted with targeted analyses. Overall, this review offers valuable insights for the coffee scientific community, exporters, importers, roasters, and consumers in recognizing the potential of Brazilian canephora coffees., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Soapstone is an abundant mineral in Ouro Preto ‐ Minas Gerais, Brazil and its main destination is in the production of craftsmanship. Rock recovery in those activities is low and the waste disposal is done with little control, which can be hazardous to the environment. This work proposes an alternative use of such potentially harmful waste as reinforcement in a novel polymer matrix composite, which can be particularly attractive to the automotive industry and of which very little information is available elsewhere in the literature. Firstly, the characterization of the waste was performed. Particle size and shape parameters were determined by automated image analysis and the mineralogical composition was determined by X‐ray diffraction, infrared, and Raman spectroscopy. High‐density polyethylene was used as matrix and the composites were made in three matrix/filler ratios: 90/10, 80/20, and 70/30 by weight. Tensile and rheological properties were measured in order to determine the influence of the particles on the polymer mechanical behavior and processing conditions. The materials showed a pseudoplastic behavior and the filler's influence was more pronounced in the 70/30 composites, which showed higher viscosities than the neat polymer. The addition of particles resulted in more brittle and rigid composites, with higher values of tensile strength. [ABSTRACT FROM AUTHOR]

• Soil elemental composition is key to infer other soil attributes. • DSM and remote sensing can take punctual XRF information to maps. • We mapped the main chemical elements using punctual XRF information and DSM. • XRF allied with DSM can be a new and low-cost way to large areas soil mapping. • Spatial XRF information can be used to access soil variations in the landscape. Spatial soil information has significantly contributed to public policy and planning. The use of X-ray fluorescence spectrometry (XRF) in soil science, primarily in laboratory settings or for isolated point analyses, has been well documented. This study broadens the application of XRF data by integrating it with remote sensing data for a comprehensive understanding of soil patterns and processes. Focusing on a 2574 km2 area in Brazil, we utilized a lab-based XRF instrument to measure the total concentrations of key chemical elements in the soil, such as Al, Si, Ti, and Fe. These geochemical data were then spatialized using the digital soil mapping (DSM) framework. We employed a synthetic bare soil image and elevation data as covariates in the analysis. The spatial accuracy assessment yielded R2 values ranging from 0.65 to 0.81 for Fe, 0.62 to 0.78 for Ti, 0.52 to 0.63 for Si, and 0.48 to 0.63 for Al. The digital soil maps of geochemical elements aligned well with existing pedological, and geological maps as evaluated using multiple correspondence analysis. The integration of spatialized XRF data with DSM and remote sensing techniques shows significant promise in assessing soil variations across landscapes based on their chemical composition. [ABSTRACT FROM AUTHOR]

Appropriate conservation and restoration of historical objects in wood must be done based on an accurate identification of species, which can indicate to the restorer the origin of material and some specificity of these objects. Little samples from nine sacred objects came from an atelier in Minas Gerais state, Brazil. Objects were from collections of churches and were in restoration process. Wood identification was based on macro and microscopic characteristics. Infrared analyses were performed in a spectrometer equipped with an integrating sphere and operating in reflectance mode in a spectral range of 4000-10000 cm-1 with resolution of 4 cm-1. Spectra were obtained directly from all surfaces of samples, without identification of section in a number of 20 by object. Six samples from sacred objects were identified, by anatomic characteristics, as from genus Cedrela P. Browne (Meliaceae). Other three samples were from genera Entandrophragma C.DC. (Meliaceae), Plathymenia Benth. (Fabaceae) and Tilia L. (Malvaceae). Principal differences in anatomic characteristics were observed in distinction of growth rings, porosity and axial parenchyma. Near infrared grouped material with similar characteristics to Cedrela sp. and showed the potential to be applied as an auxiliary tool to anatomical characterization in wood sacred objects identification. [ABSTRACT FROM AUTHOR]

Geobotanical remote sensing (GbRS) in the strict sense is an indirect approach to obtain geological information in heavily vegetated areas for mineral prospecting and geological mapping. Using ultra- and hyperspectral technologies, the goals of this research comprise the definition and mapping of Neotropical tree species that are associated with geological facies (here called geo-environments) as well as their spectral discrimination at leaf and crown scales. This work also aims to investigate the possible relationship between leaf and crown spectral and chemical properties. The study was developed at the Mogi-Guaçu Ecological Station, in the Cerrado domain, southeastern Brazil. Data from 70 sample units, such as sediment texture and species from inventories, were first analyzed through vectorial quantization using Self-Organizing Maps (SOM). Principal Component Analysis and Spearman's ranked correlation coefficients were used to define geo-environments and target-species, respectively. Biochemical and visible to shortwave infrared (VSWIR) point spectral data (350–2500 nm) were collected from the leaves of the target-species, during both rainy and dry seasons. Spectral data from target-species crowns were obtained from hyperspectral images (530–2.532 nm, ProSpecTIR-VS sensor) with 1 m spatial resolution, and acquired in the beginning of the dry season. These spectra were classified using Multiple Endmember Spectral Mixture Analysis (MESMA) with two endmembers (EMs). Based on the MESMA results with two EMs, the best dataset per target-species was chosen for pixel-based image unmixing with three EMs (target-species, other vegetation types and shade). From 121 species sampled in the field, two proved to be associated with floodplains (Alluvial Deposits sequence), two with hills and plateaus of the Aquidauna Formation (Carboniferous sedimentary rocks, Paraná Basin), and two more with a specific facies of the Aquidauna Formation that has a distinctive presence of coarse and very coarse sand. Five target-species were well discriminated at the leaf scale, reaching 90.0% and 85.0% of global accuracies in the rainy season and in the dry season, respectively. Accurate spectral discrimination appears to be linked to the considerable biochemical variability of their leaves in both seasons. Three species were discriminated at the crown scale, with 70.6% of global accuracy. When eight other landscape scale vegetation classes were included in the analyses, only Qualea grandiflora Mart. produced a satisfactory accuracy (61.1% and 100% of producer and user's accuracies, respectively). The spatial distribution of its fraction in the unmixed image, particularly, matches with the geological facies to which it was associated in the field. Ecological requirements for successfully mapping indicator species include broad and random distribution of the target-species' population, and singular physiological, phenological (and spectral) behavior at the imagery acquisition date. Our study shows that, even in tropical conditions, it is possible to use plant species mapping to support geological delineation, where rock exposures are typically rare. [ABSTRACT FROM AUTHOR]

Cemeteries are of great significance in many communities, often being considered of invaluable historical, artistic, architectural and cultural significance and thus they need to be preserved. In this regard, understanding the historical aspects and the construction techniques used is essential for their protection. The purpose of this paper is to describe historical aspects of the funerary heritage present in the region of São Martinho in southern Brazil, along with an analysis of the blue paint found in cemeteries of German colonies in the region studied. FTIR analysis suggests that the binder is composed mostly of a protein resin and a small amount of lipid. The morphology of the pigment was investigated by SEM and EDS and the spectra revealed that the major elements present in the blue pigment are Na, Al, Si and S, with an overlap in the elemental mapping, indicative of ultramarine pigments. The GC-MS results are consistent with the type of binder identified by FTIR and indicate a mixture of oils, probably from vegetal sources, and proteins. [ABSTRACT FROM AUTHOR]

Background: Spectroscopy has been shown to be a useful method to study the physicochemical properties of homeopathic preparations. Aim: In this pilot study, we compared two methods (photon scattering and visible-light spectroscopy) in the physical evaluation of Silicea terra 200cH. Methodology: Italian test: Two samples have been examined and compared: Silicea terra 200cH and Sac lac 200cH, both prepared in water solution, diluted and succussed according to German Homeopathic Pharmacopoeia (Cemon Lab, Italy). Lactose was included because the first 3 potencies of Silicea terra are made by trituration in lactose powder. Measurements were made using an innovative Charge-Coupled Device (CCD) camera developed by Daniele Gullà, called MIRA/CORA (proprietary name). Slight variations in chrominance and luminance due to micro-vibrational 3D phenomena were analyzed. All measurements have been performed in a dark room at a constant temperature of 22°C +/- 0,2°C using a filter with very narrow spectral bands (10 nm). The measurements have been repeated three times on both Silicea terra 200cH and Sac lac 200cH within a few minutes after each other. Brazilian test: In the second test, performed in Brazil, variations in absorbance were used to identify Silicea terra 200cH compared with Sac lac 200cH and compared with another control solution of non-succussed 30% alcohol, using six solvatochromic dyes, following the method developed by Cartwright [1,2]. Both homeopathic samples were imported from Italy (the same sample bottles used in the Italian test), in Brazil they have been diluted 1:100 in 30% hydro-alcoholic solution, and submitted to 100 succussions using an automatic mechanical arm (Denise, AUTIC, Brazil) prior to being tested. Samples were inserted into dyes solutions and evaluated by visible spectroscopy (FEMTO Spectrophotometer, Brazil). Dyes were prepared in ethanol P.A., according to previous established methods [3]. Three series in triplicate were performed and the results were analyzed by ANOVA / Tukey, comparing both samples and the unsuccussed 30% hydroalcoholic control solution. Results: Italian test: Measurements of the mean entropy of the signals, statistically elaborated with T Student test, yielded a two tailed p value < 0.05, where the entropy of the signal recorded from the Silicea terra 200cH sample was statistically lower than the 200cH Sac lac sample. Brazilian test: Among all tested dyes, only BDN (4-(Bis-(4- (dimethylamino)-phenyl)methylene)-1(4H)-naphthalenone) showed an interaction with Silicea terra 200cH, reproducing the conclusions obtained in [3]. Conclusions: Two different spectroscopic methods were able to show signal differences between Silicea terra 200cH and Sac lac 200cH, suggesting that changes in solvent organization could be involved in the homeopathic signaling process, along with changes in dipole moments of solvent and dyes. The results are potentially in line with a recent published paper [4], that supports the proposition that the lower entropy of the verum signal compared with controls could be explained by increased coherent vibrations of the verum sample, as theoretically explained in previous literature [5]. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the use of proximal Vis-NIR-SWIR spectroscopy to estimate technological parameters and tons of sugarcane per hectare (TSH) with the application of rock powder to the soil. It was carried out in an Arenosol area in Paranavaí , Brazil. The treatments were arranged within a split-plot system, designed in randomized blocks with four repetitions. For the experimental plots, inputs supplying calcium, magnesium, and sulfur were applied, whereas inputs supplying potassium were used for the subplots. The first and second cycles (sugarcane) were completed at 14 and 26 months, respectively, after the inputs application. During both growth cycles, technological parameters of the crop and of the TSH were determined. In addition, the stem spectrum of the crop was collected with a Vis-NIR-SWIR proximal spectroradiometer for later prediction of the parameters and TSH through the Partial Least Square Regression technique. It was possible to adjust models in the prediction phase with R2 p > 0.50 and RPD p > 1.50 for all evaluated attributes, with emphasis on three variables, namely purity, reducing sugars, and brix, which had R2 p and RPD p values above 0.86 and 2.75, respectively. The results show that proximal Vis-NIR-SWIR spectroscopy can be used to predict technological parameters and TSH of sugarcane with the application of rock powder. It offers advantages in relation to usual methods, since it is less time-consuming and low-cost, moreover it does not involve the use of toxic reagents. [Display omitted] • The application of rock powders enabled a wide diversity of spectral curves. • Technological parameters and sugarcane yield can be quantified by Vis-NIR-SWIR spectroscopy. • The SWIR region was important for the construction of the PLSR model. • Vis-NIR-SWIR spectroscopy is presented as an alternative to the analyses of sugarcane. [ABSTRACT FROM AUTHOR]

The use of satellite images is a widespread technique for estimating soil attributes. However, what is the potential of satellite data on the prediction of soil weathering indices? How much in their performance is affected by spectral mixing and data resolution? There is no consensus for answering these questions. Hence, the main objectives of this work were: i) to show the difference of spectral signature between prepared and field-condition samples; ii) to compare the convoluted data from laboratory spectroradiometer with the spectral signatures from Sentinel-2 and Landsat-8 satellites; and iii) to build and evaluate predictive models for soil weathering indices using diffuse reflectance spectroscopy from samples under natural conditions, air-dried-sieved and from satellite images. Soil samples were collected from the first 1-cm depth in 27 locations along seven catenas located in a 163-ha area in São Paulo State, Brazil. The samples were analyzed by a Vis-NIR-SWIR spectrometer without sample preparation (field conditions) and after being air-dried and sieved (prepared). The air-dried-sieved samples were also analyzed by an X-ray fluorescence equipment. Reflectance data were obtained from Sentinel and Landsat for the same 27 locations. The spectral data from the lab were convoluted to respective bands of the real satellite data. Predictive models for soil weathering indices using the convoluted laboratory data and the satellite data were also built and compared. The reflectance of samples under field conditions contrasted significantly between soils derived from basalt and sedimentary rocks. In general, the reflectance intensity of prepared samples was 80% higher than that observed for field-conditions, which can be explained by the roughness and the structure effect. However, some cases showed an opposite trend, with a smaller relative reflectance from the air-dried-sieved samples. These trends support the hypothesis of aggregates heterogeneity and clay occlusion. The sample preparation can increase or decrease the reflectance of the soil surface material, depending, mainly, on roughness, soil structure and particles occlusion by the structure. The Landsat spectral signatures were more similar to those from convoluted laboratory than to the Sentinel ones. The satellite performance on the estimation of the soil weathering indices is comparable to those from convoluted laboratory data, but it is limited by spectral resolution. Sentinel and Landsat achieved ratio of performance to interquartile distance (RPIQ) from 1.53 to 2.38 and from 1.56 to 2.42 on soil weathering indices estimation, respectively. The models for Plagioclase Index of Alteration (PIA) and Si/Ti [Si and (Ti and Al) ratio] indices were considered the best ones (RPIQ from 2.17 to 3.6; and RPIQ from 1.90 to 5.56; respectively) for both laboratory and satellite data; in turn, Si/Al, Si (Al + Fe) and Chemical Index of Alteration (CIA) indices performed poorly/reasonably (RPIQ <1.92). • The satellite performance was similar to those from convoluted laboratory data. • Sample preparation can change the reflectance of the soil surface. • The L samples showed a higher reflectance. • Landsat curves are more similar to those obtained in laboratory. • Spectral curves from Sentinel showed pronounced bands on the visible range. [ABSTRACT FROM AUTHOR]

Chemometrics has been defined as the discipline that provides maximum information from chemical data. Food science and technology applications use chemical data and are therefore suitable for chemometrics evaluation. Bibliometric studies provide an enhanced understanding of the progression, research status as well as future trends of a research field. The main aim of the study was therefore, to provide a bibliometric evaluation of the research literature employing chemometrics techniques in food science and technology applications. For this, a search strategy including the single term chemometric∗ was performed. The metadata obtained from the bibliometric search was subsequently analyzed. Indicators of the scientific productivity and quality such as the number of articles, citations, or funding activity, were obtained in combination with the most relevant keywords, authors, and countries. The progression over time of the bibliometric indicators was also presented and discussed. Chemometrics appeared as a prolific and healthy research field with increased funding received in the last decade. PCA, PLS and DA are still the preferred methods for most applications. A big part of the research is related to the combined use of spectroscopy and chemometrics. Finally, China and Brazil appeared as the leading countries in applying chemometrics to foodstuffs. • Chemometrics appeared as a prolific and healthy research field. • Chemometrics papers received increased funding in the last decade. • PCA, PLS and DA are still the methods of choice for most applications. • China and Brazil lead the chemometrics research for foodstuffs. • A strong link between chemometrics and spectroscopy was observed. [ABSTRACT FROM AUTHOR]

Introduction: A multimodal approach of the human immunodeficiency virus (HIV) encephalopathy using quantitative magnetic resonance (MR) techniques can demonstrate brain changes not detectable only with conventional magnetic resonance imaging (MRI). The aim of this study was to compare conventional MRI and MR quantitative techniques, such as magnetic resonance spectroscopy (MRS) and relaxometry and to determine whether quantitative techniques are more sensitive than conventional imaging for brain changes caused by HIV infection. Methods: We studied prospectively nine HIV positive children (mean age 6 years, from 5 to 8 years old) and nine controls (mean age 7.3 years; from 3 to 10 years), using MRS and relaxometry. Examinations were carried on 1.5-T equipment. Results: HIV-positive patients presented with only minor findings and all control patients had normal conventional MR findings. MRS findings showed an increase in choline to creatine (CHO/CRE) ratios bilaterally in both frontal gray and white matter, in the left parietal white matter, and in total CHO/CRE ratio. In contrast, N-acetylaspartate to creatine (NAA/CRE) ratios did not present with any significant difference between both groups. Relaxometry showed significant bilateral abnormalities, with lengthening of the relaxation time in HIV positive in many regions. Conclusion: Conventional MRI is not sensitive for early brain changes caused by HIV infection. Quantitative techniques such as MRS and relaxometry appear as valuable tools in the diagnosis of these early changes. Therefore, a multimodal quantitative study can be useful in demonstrating and understanding the physiopathology of the disease. [ABSTRACT FROM AUTHOR]

Although many Soil Spectral Libraries (SSLs) have been created globally, these libraries still have not been operationalized for end-users. To address this limitation, this study created an online Brazilian Soil Spectral Service (BraSpecS). The system was based on the Brazilian Soil Spectral Library (BSSL) with samples collected in the Visible–Near–Short-wave infrared (vis–NIR–SWIR) and Mid-infrared (MIR) ranges. The interactive platform allows users to find spectra, act as custodians of the data, and estimate several soil properties and classification. The system was tested by 500 Brazilian and 65 international users. Users accessed the platform (besbbr.com.br), uploaded their spectra, and received soil organic carbon (SOC) and clay content prediction results via email. The BraSpecS prediction provided good results for Brazilian data, but performed variably for other countries. Prediction for countries outside of Brazil using local spectra (External Country Soil Spectral Libraries, ExCSSL) mostly showed greater performance than BraSpecS. Clay R2 ranged from 0.5 (BraSpecS) to 0.8 (ExCSSL) in vis–NIR–SWIR, but BraSpecS MIR models were more accurate in most situations. The development of external models based on the fusion of local samples with BSSL formed the Global Soil Spectral Library (GSSL). The GSSL models improved soil properties prediction for different countries. Nevertheless, the proposed system needs to be continually updated with new spectra so they can be applied broadly. Accordingly, the online system is dynamic, users can contribute their data and the models will adapt to local information. Our community-driven web platform allows users to predict soil attributes without learning soil spectral modeling, which will invite end-users to utilize this powerful technique. [ABSTRACT FROM AUTHOR]

Ceramic fragments can provide an insight into the ancient culture and practices of groups of humans and their way of life (technology, cultural identity, social organization, habitation and economy). Scientific analysis can be used to obtain information on the ceramic production process, as well as the specificities of the material employed. In this research, all samples of archaeological potsherd from the Tupi-Guarani tradition were analyzed in order to identify and to characterize the structures, morphologies and the elemental composition by using by scanning electron microscopy (SEM-EDS) and multivariate statistical methods (PCA and HCA). FTIR spectroscopy revealed the presence of an organic residue in three samples along with carbonates, clay minerals, quartz and hematite. In addition, the presence of the stretching attributed to water molecules in crystalline systems was observed. Also, the presence of TiO2 in the anatase polymorphic form was detected using μ-Raman spectroscopy. These results indicate a firing temperature of between 800 and 1000 °C. In relation to the morphology, all samples revealed amorphous structures presenting isolated and heterogenic particles of different forms and sizes, and the EDS spectrum confirmed the elements present in the molecular structures elucidated by vibrational spectroscopy. The multivariate analysis has confirmed the correlation between the elemental compositions of ceramics collected from two different sites: a mountain region and a coastal area in Santa Catarina State, Brazil. [Display omitted] • Archaeological ceramic samples found in Florianópolis, SC, Brazil were submitted to material analysis. • The molecular structures were characterized by FTIR and micro-Raman spectroscopy. • Morphological and elemental analyses were conducted by SEM-EDS. • The results suggest the firing temperatures were between 800 and 1000 °C. • Chemometric analysis elucidated a possible correlation between ceramics from two different sites. [ABSTRACT FROM AUTHOR]

• The sensors provide complementary and useful information about the soil profile horizonation. • PHI values are affected by soil-forming factors and processes. • The higher PHI values were mainly related to the erosion and redeposition processes. • The PHI was useful to study soil genesis and layers differentiation. The technological and computational development has raised new possibilities for soil scientists to describe and infer about soil-forming processes and functions. Thus, why not to insert the contrasts between soil layers in a profile revealed by proximal sensing? We proposed to study the soil profile heterogeneity by reflectance (Vis-NIR-SWIR), X-ray fluorescence and magnetic susceptibility aiming to quantify it with the proposed "Profile Heterogeneity Index" (PHI) through seven soil sequences in twenty-seven locations over different hillslope positions and parent materials. The study was conducted in a 165-ha farm, at Rio das Pedras municipality, São Paulo State, Brazil. The differences between two consecutive soil layers were calculated by subtracting the data to the bottom and the immediately above for each soil profile. The results are depicted as a depth function with proportional colors to highlight the heterogeneity in the soil profiles. This approach provided a new method to identify where the transitions of soil attributes occur exactly and improve the understanding about soil-formation factors and processes. In this study, greater PHI values were mainly related to erosion and redeposition process through the landscape, differences in soil parent materials and also soil-forming processes. The sensors can furnish important and complementary information to the characterization of soil profile heterogeneity. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was to characterize the humic acids (HAs) in spodosols developed on quartzitic, sandy, nutrient-poor parent materials under restinga forest. 13C NMR and FTIR spectroscopy were used to obtain information about the mechanism of podzolization in tropical climates in three sandy coastal podzols (Histic Alaquod, Typic Alorthod and Arenic Alorthod) from Cardoso Island (Sao Paulo-Brazil). HAs were extracted from all horizons and 13C NMR and FTIR measurements were performed on all HA samples. Similarities between the surface horizon A from a Typic Alorthod (C14) and the Ho horizon from a Histic Alaquod (H13) were observed. Below the E horizon, the spectra of profile H13 closely resembled the spectra of C14. The increase in alkyl carbon and decrease in acetal carbon, aromatic C and phenolic C with increasing depth suggests enrichment of methylene structures by the microbial biomass. This idea was further supported by an increase in the decomposition of polysaccharides and lignin throughout the profiles. The similarity of the composition may be evidence of vertical translocation throughout the profile, with no incorporation of organic matter (OM) components from other sources such as roots or their residues. The chemical structure of profile Arenic Alorthod (H9) differed from that of the other profiles. The increase in methoxylic, aromatic and phenolic groups as depth increased probably indicates an increase in tannin-like compounds with depth. The higher content of tannins in this soil indicates the presence of more fresh litter and/or a less intense decomposition process than in Histic Alaquod and Typic Alorthod soils. In the latter soil the large amounts of aliphatics and small amounts of lignin-derived products reflect strong aerobic decay. The presence of significant methylene absorption in the FTIR spectra indicates that this alkyl material was dominated by the mobile lignin-derived products, in accordance with the NMR results, which revealed that the HAs have greater aliphatic than aromatic character. [Copyright &y& Elsevier]

Geotechnologies allow natural resources to be surveyed more quickly and cheaply than traditional methods. This paper aimed to produce a digital soil map (DSM) based on Landsat time series data. The study area, located in the eastern part of the Brazilian Federal District (Rio Preto hydrographic basin), comprises a representative basin of the Central Brazil plateau in terms of pedodiversity. A spectral library was produced based on the soil spectroscopy (from the visible to shortwave infrared spectral range) of 42 soil samples from 0–15 cm depth using the Fieldspec Pro equipment in a laboratory. Pearson's correlation and principal component analysis of the soil attributes revealed that the dataset could be grouped based on the texture content. Hierarchical clustering analysis allowed for the extraction of 13 reference spectra. We interpreted the spectra morphologically and resampled them to the Landsat 5 Thematic Mapper satellite bands. Afterward, we elaborated a synthetic soil/rock image (SySI) and a soil frequency image (number of times the bare soil was captured) from the Landsat time series (1984–2020) in the Google Earth Engine platform. Multiple Endmember Spectral Mixture Analysis (MESMA) was used to model the SySI, using the endmembers as the input and generating a DSM, which was validated by the Kappa index and the confusion matrix. MESMA successfully modeled 9 of the 13 endmembers: Dystric Rhodic Ferralsol (clayic); Dystric Rhodic Ferralsol (very clayic); Dystric Haplic Ferralsol (loam-clayic); Dystric Haplic Ferralsol (clayic); Dystric Petric Plinthosol (clayic); Dystric Petric Plinthosol (very clayic); Dystric Regosol (clayic); Dystric Regosol (very clayic); and Dystric, Haplic Cambisol (clayic). The root mean squared error (RMSE) varied from 0 to 1.3%. The accuracy of DSM achieved a Kappa index of 0.74, describing the methodology's effectiveness to differentiate the studied soils. [ABSTRACT FROM AUTHOR]

• Removals of iron forms and organic matter alter absorption features in the mid-IR. • The addition of water have stronger influence in sandy than in clay soil. • High correlation values were observed for Kt, Gb, SiO 2 and Fe 2 O 3 with ASTER bands. • New mid-IR regions have been proposed for satellite remote sensing. The soil mineralogical constitution directly influences its chemical, physical and hydraulic characteristics. Although very important, it is still rarely used for decision-making in agriculture, mainly due to the complexity and cost of standard analyzes. In this sense, the middle infrared spectroscopy (mid-IR, 4000 to 400 cm−1) has great potential to obtain soil mineralogical information quickly and accurately. Nevertheless, some soil constituents can severely influence the spectra and produce misinterpretations. In this research, we aim to detect changes in the mid-IR spectra caused by water, iron forms and organic matter (OM), and to relate soil attributes to laboratory spectra and remote sensing simulated spectral bands. The research area is located in São Paulo State, Brazil, where seventeen soil samples were collected. The reflectance intensities, shapes and absorption features of the mid-IR spectra before and after the removal of OM and iron forms and the addition of water were described. Soil attributes, such as kaolinite, gibbsite, 2:1 minerals among others were correlated with the mid-IR spectra and simulated ASTER spectral bands by Pearson's analysis, to verify its potential on mineralogical evaluation. The description of mid-IR revealed that the removal of the OM from the soil samples decreased the reflectance intensities between 4000 and 2000 cm−1. Iron forms mainly influence the 3250 – 1200 cm−1 spectral range and mask the spectral features of other minerals as well. The addition of water masked several absorption features and decreased the reflectance intensities from 3700 to 2700 cm−1. High correlation coefficients were obtained between soil attributes and ASTER simulated spectral bands, which allowed the selection of potential spectral regions for future satellite sensors: 2760 – 2500 cm−1 (3600 – 4000 nm), 2150 – 1875 cm−1 (4600 – 5300 nm), and 840 – 740 cm−1 (11900 – 3500 nm). [ABSTRACT FROM AUTHOR]

• Spectroscopy provided an important indicator that reflects soil properties. • The technique allowed to obtain iron oxide concentrations. • We suggest a classification for iron oxide proportions in the soil. • Iron oxides, color parameters and color of subtropical soils have been mapped. The color of soils provides useful information about their origin and allows their classification. Soil color has traditionally been determined with a Munsell chart; lately, however, alternative techniques such as diffuse reflectance spectroscopy (DRS) have enabled more accurate quantification. In this work, we determined the color parameters hue, value, chroma and reddening index using a Munsell chart and a DRS instrument for comparison. The data obtained from the DRS measurements were used to develop an accurate soil color map for the Rio Grande do Sul state in Brazil (RS). DRS data were also used for removable continuum calculations to determine the [hematite/(hematite + goethite)] ratio [Hm/(Hm + Gt)] of Brazilian soils. Based on suchratio, the soils were classified as goethitic [Hm/(Hm + Gt) ≤ 25%], goethitic–hematitic [25 < Hm/(Hm + Gt) ≤ 50%], hematitic–goethitic [50 < Hm/(Hm + Gt) ≤ 75%] or hematitic [Hm/(Hm + Gt) ≥ 25%]. Color parameters differed between the two measurement methods, with the Munsell chart often overestimating or underestimating the DRS results. Based on the [Hm/(Hm + Gt)] ratio, the target soils were mainly goethitic. [ABSTRACT FROM AUTHOR]

In this work, over the course of four seasons (12 months), we have monitored the fluorescence quantum efficiency (η) from two sets (S1 and S2) of fresh natural dye extracts from the leaves of Tradescantia pallida purpurea. The natural dye was extracted in aqueous solutions from leaves collected from regions with a predominance of shade (S1) and sun (S2) during the day. The thermo-optical parameter fractional thermal load (φ) was measured using conical diffraction (CD) patterns caused by thermally driven self-phase modulation, for η determination in both sets of solutions. Fluorescence measurements corroborate the CD results, and the η values are, on average, slightly higher (~ 11%) in the summer than in the other seasons for both sets of samples (S1 and S2). In addition, the experimental results are presented using natural dye extracted from Tradescantia pallida purpurea as a fungicide probe in Fusarium solani , Sclerotinia sclerotiorum , and Colletotrichum gloeosporioides fungi. The promising fungicide results obtained for the aqueous natural dye extract were compared with those obtained for other natural dyes and fungi. The fungi tested are of the necrotrophic group and constitute important pathosystems in Brazil, causing diseases in several crops that synthetic fungicides often cannot control or do so with low efficiency. Unlabelled Image • Natural dyes were extracted from the leaves of Tradescantia pallida purpurea. • The extraction was performed from leaves collected from regions with shade and sun. • The fluorescence quantum efficiency (η) was evaluated as a function of the seasons. • Fluorescence measurements corroborate the η results. • Anthocyanin extract was tested as a fungicide probe in fungi. [ABSTRACT FROM AUTHOR]