NMR Fingerprinting of Conventional and Genetically Modified Soybean Plants with AtAREB1 Transcription Factors.

Drought stress impacts soybean yields and physiological processes. However, the insertion of the activated form of the AtAREB1 gene in the soybean cultivar BR16, which is sensitive to water deficit, improved the drought response of the genetically modified plants. Thus, in this study, we used 1H NMR in solution and solid-state NMR to investigate the response of genetically modified soybean overexpressing AtAREB1 under water deficiency conditions. We achieved that drought-tolerant soybean yields high content of amino acids isoleucine, leucine, threonine, valine, proline, glutamate, aspartate, asparagine, tyrosine, and phenylalanine after 12 days of drought stress conditions, as compared to drought-sensitive soybean under the same conditions. Specific target compounds, including sugars, organic acids, and phenolic compounds, were identified as involved in controlling sensitive soybean during the vegetative stage. Solid-state NMR was used to study the impact of drought stress on starch and cellulose contents in different soybean genotypes. The findings provide insights into the metabolic adjustments of soybean overexpressing AREB transcription factors in adapting to dry climates. This study presents NMR techniques for investigating the metabolome of transgenic soybean plants in response to the water deficit. The approach allowed for the identification of physiological and morphological changes in drought-resistant and drought-tolerant soybean tissues. The findings indicate that drought stress significantly alters micro- and macromolecular metabolism in soybean plants. Differential responses were observed among roots and leaves as well as drought-tolerant and drought-sensitive cultivars, highlighting the complex interplay between overexpressed transcription factors and drought stress in soybean plants.

Lipidome and metabolome profiling of longissimus lumborum beef with different ultimate pH and postmortem aging.

The objective of this exploratory study was to assess the changes on lipidome and metabolome profiling of Longissimus lumborum bull muscle with different ultimate pH (pHu) and aging periods. The bull muscles classified as normal, intermediate, or high pHu were collected from a Brazilian commercial slaughterhouse, cut into steaks, individually vacuum-packaged, and aged for 3 days (3-d) or 21 days (21-d) at 2 °C. Muscle extracts were analyzed for the profiles of both lipids, by mass spectrometry (via direct flow-injection), and metabolites, by nuclear magnetic resonance, with downstream multivariate data analysis. As major results, pairwise comparisons identified C12:0 and C14:0 acylcarnitines as potential biomarkers of the intermediate pHu-muscle, which are related to lipid catabolism for alternative energy metabolism and indicate less protein breakage postmortem. Interestingly, the concentration of arginine at early postmortem aging (3-d) may influence the previously reported improved tenderness in normal and high pHu-muscles. Moreover, upregulation of fumarate, formate, and acetate with increased pHu muscle at 21-d aging indicate more intense tricarboxylic acid cycle, amino acid degradation, and pyruvate oxidation by reactive oxygen species, respectively. These three compounds (fumarate, formate, and acetate) discriminated statistically the muscle with high pHu at 21-d aging. The normal pHu-muscle showed higher concentrations of glycogenolysis and glycolysis metabolites, including glucose, mannose, and pyruvate. Hence, our results enhance knowledge of postmortem biochemical changes of beef within different pHu groups aged up to 21 days, which is essential to understand the mechanisms underpinning bull meat quality changes.

Nanostructured gadolinium(III) micelles: Synthesis, characterization, cytotoxic activities, and MRI applications in vivo.

Gadolinium-based contrast agents (GBCAs) are used in around 40 % of MRI procedures. Despite initial perceptions of minimal risk, their long-term use has emphasized the need to reduce toxicity and develop more efficient GBCAs with extended blood retention. Advancements in nanomaterials have led to improved GBCAs, enhancing MRI diagnostics. This study synthesizes and characterizes nanostructured gadolinium(III) micelles as superior MRI contrast agents. The complexes, [Gd(L)2], where L is a ligand of the N-alkyl-N-methylglucamine surfactant series (L8, L10 or L12, L10), form nanostructured micelles in aqueous solution. Gd(L8)2 and Gd(L10)2 relaxivities remained stable across concentrations. Compared to Gd-DTPA, Gd(III) micelles showed enhanced T1-weighted MRI contrast. Gd(L12)2 micelles exhibited cytotoxicity against B16F10 melanoma cells (IC50 42.5 ± 2.2 µM) and L292L929 fibroblasts (IC50 52.0 ± 2.5 µM), with a selectivity index of 1.2. In vivo application in mice brain T2-weighted images suggests nanostructured Gd(III) micelles are promising MRI contrast agents for targeting healthy organs or tumors.

Influence of plant growth-promoting bacteria on leaf carbon and nitrogen metabolism of two drought-stressed neotropical tree species: a metabolomic approach.

Deforestation of Atlantic Forest has caused prolonged drought events in the last decades. The need for reforestation is growing, and the development of native seedlings that are more tolerant to drought stress is necessary. A biotechnological tool that improves plant tolerance is the use of plant growth-promoting bacteria (PGPB) as inoculants. Two species of PGPB were inoculated in drought-stressed seedlings of two neotropical tree species that have been used in environmental restoration programs: Cecropia pachystachya and Cariniana estrellensis. Biometrical, physiological, and metabolomic parameters from carbon and nitrogen pathways were evaluated. We found that the PGPB positively influenced photosynthesis and growth parameters in both trees under drought. The enzymes activities, the tricarboxylic acid cycle intermediates, the amino acids, and protein contents were also influenced by the PGPB treatments. The results allowed us to find the specific composition of secondary metabolites of each plant species. This study provides evidence that there is not a single mechanism involved in drought tolerance and that the inoculation with PGPB promotes a broad-spectrum tolerance response in Neotropical trees. The inoculation with PGPB appears as an important strategy to improve drought tolerance in Atlantic Forest native trees and enhance environmental restoration programs' success. MAIN CONCLUSION: The association with plant growth-promoting bacteria improved the tolerance to drought in Neotropical trees through biochemical, physiological, and biometrical parameters. This can enhance the success of forest restoration programs.

NMR Longitudinal Rotating Frame Relaxation Time (T1ρ) with a Weak Spin Locking Field as an Approach to Characterize Solid-State Active Pharmaceutical Ingredients: Proof of Concept.

Nuclear magnetic resonance (NMR) longitudinal rotating frame relaxation time (T1ρ), rarely used in low-field NMR, can be more effective than conventional T1 and T2 relaxation times to differentiate polymorphic forms of solid pharmaceuticals. This could be attributed to T1ρ sensibility to structural and molecular dynamics that can be enhanced by changing the strength of the oscillating magnetic field (B1) of spinlock pulses. Here, we compared the capacity of T1, T2, and T1ρ to differentiate inactive (A) and active (C) crystalline forms of the World Health Organization essential drug Mebendazole. The results showed that T1 and T2 values of both forms were statistically identical at 0.47 T. Conversely, T1ρ of both forms measured with weak spinlock B1 fields, ranging from 0.08 to 0.80 mT were statistically different in the same spectrometer. The T1ρ also has the limit of detection to detect the presence of at least 10% of inactive A form in the active C form. Therefore, T1ρ, measured with weak spinlock B1 fields can be an effective, streamlined, and complementary approach for characterizing not only solid active pharmaceutical ingredients but other solid-state materials as well.

Impact of ZrO2 Content on the Formation of Sr-Enriched Phosphates in Al2O3/ZrO2 Nanocomposites for Bone Tissue Engineering.

This study investigates the profound impact of the ZrO2 inclusion volume on the characteristics of Al2O3/ZrO2 nanocomposites, particularly influencing the formation of calcium phosphates on the surface. This research, aimed at advancing tissue engineering, prepared nanocomposites with 5, 10, and 15 vol% ZrO2, subjecting them to chemical surface treatment for enhanced calcium phosphate deposition sites. Biomimetic coating with Sr-enriched simulated body fluid (SBF) further enhanced the bioactivity of nanocomposites. While the ZrO2 concentration heightened the oxygen availability on nanocomposite surfaces, the quantity of Sr-containing phosphate was comparatively less influenced than the formation of calcium phosphate phases. Notably, the coated nanocomposites exhibited a high cell viability and no toxicity, signifying their potential in bone tissue engineering. Overall, these findings contribute to the development of regenerative biomaterials, holding promise for enhancing bone regeneration therapies.

Activity of a Recombinant Chitinase of the Atta sexdens Ant on Different Forms of Chitin and Its Fungicidal Effect against Lasiodiplodia theobromae.

This study evaluates the activity of a recombinant chitinase from the leaf-cutting ant Atta sexdens (AsChtII-C4B1) against colloidal and solid α- and ß-chitin substrates. 1H NMR analyses of the reaction media showed the formation of N-acetylglucosamine (GlcNAc) as the hydrolysis product. Viscometry analyses revealed a reduction in the viscosity of chitin solutions, indicating that the enzyme decreases their molecular masses. Both solid state 13C NMR and XRD analyses showed minor differences in chitin crystallinity pre- and post-reaction, indicative of partial hydrolysis under the studied conditions, resulting in the formation of GlcNAc and a reduction in molecular mass. However, the enzyme was unable to completely degrade the chitin samples, as they retained most of their solid-state structure. It was also observed that the enzyme acts progressively and with a greater activity on α-chitin than on ß-chitin. AsChtII-C4B1 significantly changed the hyphae of the phytopathogenic fungus Lasiodiplodia theobromae, hindering its growth in both solid and liquid media and reducing its dry biomass by approximately 61%. The results demonstrate that AsChtII-C4B1 could be applied as an agent for the bioproduction of chitin derivatives and as a potential antifungal agent.

Muscle growth affects the metabolome of the pectoralis major muscle in red-winged tinamou (Rhynchotus rufescens).

The aim of the present study was to identify and quantify the metabolites (metabolome analysis) of the pectoralis major muscle in male red-winged tinamou (Rhynchotus rufescens) selected for growth traits. A selection index was developed for females [body weight (BW), chest circumference (CC), and thigh circumference (TC)] and males [BW, CC, TC, semen volume, and sperm concentration] in order to divide the animals into 2 experimental groups: selection group with a higher index (TinamouS) and commercial group with a lower index (TinamouC). Twenty male offspring of the 2 groups (TinamouS, n = 10; TinamouC, n = 10) were confined for 350 d. The birds were slaughtered and pectoralis major muscle samples were collected, subjected to polar and apolar metabolites extractions and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Analysis of the polar metabolomic profile identified 65 metabolites; 29 of them were differentially expressed between the experimental groups (P < 0.05). The TinamouS groups exhibited significantly higher concentrations (P < 0.05) of 25 metabolites, including anserine, aspartate, betaine, carnosine, creatine, glutamate, threonine, 3-methylhistidine, NAD+, pyruvate, and taurine. Significantly higher concentrations of cysteine, beta-alanine, lactose, and choline were observed in the TinamouC group (P < 0.05). The metabolites identified in the muscle provided information about the main metabolic pathways (higher impact value and P < 0.05), for example, phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; D-glutamine and D-glutamate metabolism; ß-alanine metabolism; glycine, serine and threonine metabolism; taurine and hypotaurine metabolism; histidine metabolism; phenylalanine metabolism. The NMR spectra of apolar fraction showed 8 classes of chemical compounds. The metabolome analysis shows that the selection index resulted in the upregulation of polyunsaturated fatty acids, unsaturated fatty acids, phosphocholines, phosphoethanolamines, triacylglycerols, and glycerophospholipids. The present study suggests that, despite few generations, the selection based on muscle growth traits promoted changes in metabolite concentrations in red-winged tinamou.

Ruminal and feces metabolites associated with feed efficiency, water intake and methane emission in Nelore bulls.

The objectives of this study were twofold: (1) to identify potential differences in the ruminal and fecal metabolite profiles of Nelore bulls under different nutritional interventions; and (2) to identify metabolites associated with cattle sustainability related-traits. We used different nutritional interventions in the feedlot: conventional (Conv; n = 26), and by-product (ByPr, n = 26). Thirty-eight ruminal fluid and 27 fecal metabolites were significantly different (P < 0.05) between the ByPr and Conv groups. Individual dry matter intake (DMI), residual feed intake (RFI), observed water intake (OWI), predicted water intake (WI), and residual water intake (RWI) phenotypes were lower (P < 0.05) in the Conv group, while the ByPr group exhibited lower methane emission (ME) (P < 0.05). Ruminal fluid dimethylamine was significantly associated (P < 0.05) with DMI, RFI, FE (feed efficiency), OWI and WI. Aspartate was associated (P < 0.05) with DMI, RFI, FE and WI. Fecal C22:1n9 was significantly associated with OWI and RWI (P < 0.05). Fatty acid C14:0 and hypoxanthine were significantly associated with DMI and RFI (P < 0.05). The results demonstrated that different nutritional interventions alter ruminal and fecal metabolites and provided new insights into the relationship of these metabolites with feed efficiency and water intake traits in Nelore bulls.

Quality Attributes and Metabolic Profiles of Uvaia (Eugenia pyriformis), a Native Brazilian Atlantic Forest Fruit.

The uvaia is a native Brazilian Atlantic Forest Myrtaceae fruit with a soft pulp, ranging from yellow to orange, with a sweet acidic flavor and sweet fruity aroma. Uvaias present consumption potential, but their physicochemical characteristics are still understudied. In this context, we describe herein the metabolites of uvaia that have been determined by nuclear magnetic resonance spectroscopy. We screened 41 accessions and selected 10 accessions based on their diversity of physicochemical attributes, i.e., their fresh mass, height, diameter, yield, seed mass, total soluble solids, and titratable acidity. Twenty-six metabolites were identified, including sugars, acids, and amino acids. The results of this study comprise the most complete report on sugars and acids in uvaias. The relevant metabolites in terms of abundance were the reducing sugars glucose and fructose, as well as malic and citric acids. Furthermore, this study represents the first description of the uvaia amino acid profile and an outline of its metabolic pathways. Uvaia quality attributes differ among accessions, demonstrating high variability, diversity, and several possibilities in different economic areas. Our findings may help in future breeding programs in the selection of plant material for industries such as food and pharmaceuticals.

Dynamics of the role of LacMeta laccase in the complete degradation and detoxification of malachite green.

Laccases highlight for xenobiotic bioremediation, as well as application in the fine chemical, textile, biofuel and food industries. In a previous work, we described the preliminary characterization of laccase LacMeta, a promising enzyme for the bioremediation of dyes, able to decolorization malachite green (MG), trypan blue, methylene blue. Here we demonstrate that LacMeta is indeed suitable for the complete degradation and detoxification of MG dye, not just for its discoloration, since some works show false positives due to the formation of colorless intermediates such as leucomalachite. The optimal pH and temperature parameters of LacMeta were 5.0 and 50 °C, respectively (MG as substrate). LacMeta was tolerant of up to 10 mmol L- 1 EDTA (82%) and up to 5% (V/V) acetone (91%) and methanol (71%), while SDS promoted severe inhibition. For ions, a high tolerance to cobalt, zinc, manganese, and calcium (10 mmol L- 1) was also observed (> 90%). Even under high-salinity conditions (1 mol L- 1 NaCl), the residual bleaching activity of the dye remained at 61%. Furthermore, the bleaching product of MG did not inhibit the germination of sorghum and tomato seeds and was inert to the vegetative structures of the germinated seedlings. Additionally, this treatment effectively reduced the cytotoxic effect of the dye on microorganisms (Escherichia coli and Azospirillum brasilense), which can be explained by H-NMR spectral analysis results since LacMeta completely degraded the peak signals corresponding to the aromatic rings in the dye, demonstrating extreme efficiency in the bioremediation of the xenobiotic at high concentrations (50 mg L- 1).

NMR-Based Metabolomics Reveals Effects of Water Stress in the Primary and Specialized Metabolisms of Bauhinia ungulata L. (Fabaceae).

Bauhinia ungulata is a plant used in Brazilian traditional medicine for the treatment of diabetes. Phytochemical studies revealed flavonoids and the saccharide pinitol related to hypoglycemic activity of the Bauhinia species. To determine the effects of water deficit on ecophysiological parameter and metabolite fingerprints of B. ungulata, specimens were treated with the following water regimens under greenhouse conditions: daily watering (control), watering every 7 days (group 7D), and watering every 15 days (group 15D). Metabolite profiling of the plants subjected to water deficit was determined by LC-HRMS/MS. An NMR-based metabolomics approach applied to analyze the extracts revealed increased levels of known osmoprotective and bioactive compounds, such as D-pinitol, in the water deficit groups. Physiological parameters were determined by gas exchange in planta analysis. The results demonstrated a significant decrease in gas exchange under severe drought stress, while biomass production was not significantly different between the control and group 7D under moderate stress. Altogether, the results revealed that primary and specialized/secondary metabolism is affected by long periods of severe water scarcity downregulating the biosynthesis of bioactive metabolites such as pinitol, and the flavonoids quercetin and kaempferol. These results may be useful for guiding agricultural production and standardizing medicinal herb materials of this medicinal plant.

Magnetic Resonance and Vibrational Spectroscopy and Imaging in Food Analysis.

In the past two decades, there have been remarkable changes in the way we analyze the physical, chemical, and sensory properties of fresh and processed food products, with the progressive replacement of traditional wet analytical methods (destructive, laborious, time-consuming, and requiring the use of hazardous chemicals) with new, fast, non-destructive physical methods where the analysis is performed in a single step, after validation, and without the use of chemical reagents [...].

Effect of the application of vermicompost and millicompost humic acids about the soybean microbiome under water restriction conditions.

Humic substances (HSs) are constituent fractions of organic matter and are highly complex and biologically active. These substances include humic acids (HA), fulvic acids (FA), and humin. HS are known to stimulate the root system and plant growth and to mitigate stress damage, including hydric stress. Humic acids have already been reported to increase microbial growth, affecting their beneficial effect on plants. However, there is scarce information on whether HA from vermicompost and millicompost, along with Bradyrhizobium, improves the tolerance of soybean to water restriction. This study aimed to evaluate the responses of soybean plants to the application of vermicompost HA (HA-V) and millicompost (HA-M) along with Bradyrhizobium sp. under water restriction. The experiment was carried out in a greenhouse, and the treatments received Bradyrhizobium sp. inoculation with or without the application of HA from vermicompost and millicompost with or without water restriction. The results showed that HA provided greater soybean growth and nodulation than the control. The application of HA-M stimulated an increase in the richness of bacterial species in roots compared to the other treatments. After the application of water stress, the difference between the treatments disappeared. Microbial taxa were differentially abundant in plants, with the fungal fraction most affected by HA application in stressed roots. HA-V appears to be more prominent in inducing taxa under stress conditions. Although the results showed slight differences between HA from vermicompost and millicompost regarding plant growth, both humic acids promoted an increase in plant development compared to the control.

Head-to-Tail and Head-to-Head Molecular Chains of Poly(p-Anisidine): Combined Experimental and Theoretical Evaluation.

Poly(p-anisidine) (PPA) is a polyaniline derivative presenting a methoxy (-OCH3) group at the para position of the phenyl ring. Considering the important role of conjugated polymers in novel technological applications, a systematic, combined experimental and theoretical investigation was performed to obtain more insight into the crystallization process of PPA. Conventional oxidative polymerization of p-anisidine monomer was based on a central composite rotational design (CCRD). The effects of the concentration of the monomer, ammonium persulfate (APS), and HCl on the percentage of crystallinity were considered. Several experimental techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), multifractal analysis, Nuclear Magnetic Resonance (13C NMR), Fourier-transform Infrared spectroscopy (FTIR), and complex impedance spectroscopy analysis, in addition to Density Functional Theory (DFT), were employed to perform a systematic investigation of PPA. The experimental treatments resulted in different crystal structures with a percentage of crystallinity ranging from (29.2 ± 0.6)% (PPA1HT) to (55.1 ± 0.2)% (PPA16HT-HH). A broad halo in the PPA16HT-HH pattern from 2θ = 10.0-30.0° suggested a reduced crystallinity. Needle and globular-particle morphologies were observed in both samples; the needle morphology might have been related to the crystalline contribution. A multifractal analysis showed that the PPA surface became more complex when the crystallinity was reduced. The proposed molecular structures of PPA were supported by the high-resolution 13C NMR results, allowing us to access the percentage of head-to-tail (HT) and head-to-head (HH) molecular structures. When comparing the calculated and experimental FTIR spectra, the most pronounced changes were observed in ν(C-H), ν(N-H), ν(C-O), and ν(C-N-C) due to the influence of counterions on the polymer backbone as well as the different mechanisms of polymerization. Finally, a significant difference in the electrical conductivity was observed in the range of 1.00 × 10-9 S.cm-1 and 3.90 × 10-14 S.cm-1, respectively, for PPA1HT and PPA16HT-HH.

Miniaturized Carbon Fiber Paper Electrodes for In Situ High Resolution NMR Analyses.

Combining spectroscopic techniques with electrochemistry is a promising strategy, as it allows the detailed investigation of the species that are consumed and produced by the reaction in real time. However, as with any in situ coupling technique, the junction between NMR and electrochemistry presents some challenges, notably the distortion of NMR signals due to the placement of electrodes close to or within the detection region. In this work, miniaturized electrodes made of carbon fiber paper were developed and later modified with platinum. Platinum decoration by cathodic deposition was chosen, as platinum is a prominent element in electrocatalysis, able to catalyze a large variety of reactions. To evaluate the efficiency of this electrochemical system, the oxidation of ascorbic acid was used as a model reaction. It was observed that the electrodes caused substantial signal distortion when placed within the detection region (full width at half-maximum equal to 1.46 Hz), whereas no distortion was observed when the electrodes were placed 1 mm above the detection region (full width at half-maximum equal to 0.95 Hz). With this system, it was also possible to monitor the magnetoelectrolysis effect, caused by the interaction of the magnetic field with the flowing ions, leading to a doubling of the ascorbic acid oxidation rate, compared to the reaction performed without a magnetic field. In addition to its low cost and simplicity in preparation, the developed electrode system allows the electrode surface to be easily modified with other suitable catalysts.

Impact of Cattle Feeding Strategy on the Beef Metabolome.

The present study explored changes in the meat metabolome of animals subjected to different finishing systems and growth rates. Thirty-six Angus × Nellore crossbred steers were used in a completely randomized design with four treatments: (1) feedlot system with high average daily gain (ADG; FH); (2) feedlot system with low ADG (FL); (3) pasture system with high ADG (PH); and (4) pasture system with low ADG (PL). After harvest and chilling, Longissimus thoracis (LT) muscle samples were taken for metabolite profile analysis using nuclear magnetic resonance. Spectrum was analyzed using chenomx software, and multi- and mega-variate data analyses were performed. The PLS-DA showed clear separation between FH and PL groups and overlap among treatments with different finishing systems but similar for matching ADG (FL and PH) treatments. Using a VIP cut-off of around 1.0, ATP and fumarate were shown to be greater in meat from PL cattle, while succinate, leucine, AMP, glutamate, carnosine, inosine, methionine, G1P, and choline were greater in meat from FH. Comparing FL and PH treatments, glutamine, carnosine, urea, NAD+, malonate, lactate, isoleucine, and alanine were greater in the meat of PH cattle, while G6P and betaine were elevated in that of FL cattle. Relevant pathways were also identified by differences in growth rate (FH versus PL) and finishing system were also noted. Growth rate caused a clear difference in meat metabolism that was highlighted by energy metabolism and associated pathways, while the feeding system tended to alter protein and lipid metabolism.

Non-Invasive Method to Predict the Composition of Requeijão Cremoso Directly in Commercial Packages Using Time Domain NMR Relaxometry and Chemometrics.

Low Field Time-Domain Nuclear Magnetic Resonance (TD-NMR) relaxometry was used to determine moisture, fat, and defatted dry matter contents in "requeijão cremoso" (RC) processed cheese directly in commercial packaged (plastic cups or tubes with approximately 200 g). Forty-five samples of commercial RC types (traditional, light, lactose-free, vegan, and fiber) were analyzed using longitudinal (T1) and transverse (T2) relaxation measurements in a wide bore Halbach magnet (0.23 T) with a 100 mm probe. The T1 and T2 analyses were performed using CWFP-T1 (Continuous Wave Free Precession) and CPMG (Carr-Purcell-Meiboom-Gill) single shot pulses. The scores of the principal component analysis (PCA) of CWFP-T1 and CPMG signals did not show clustering related to the RC types. Optimization by variable selection was carried out with ordered predictors selection (OPS), providing simpler and predictive partial least squares (PLS) calibration models. The best results were obtained with CWFP-T1 data, with root-mean-square errors of prediction (RMSEP) of 1.38, 4.71, 3.28, and 3.00% for defatted dry mass, fat in the dry and wet matter, and moisture, respectively. Therefore, CWFP-T1 data modeled with chemometrics can be a fast method to monitor the quality of RC directly in commercial packages.

Monitoring Stimulated Darkening from UV-C Light on Different Bean Genotypes by NMR Spectroscopy.

The use of UV-C cool white light on bean (Phaseolus vulgaris L.) seeds significantly increases the biochemical seed coat post-harvest darkening process, whilst preserving seed germination. The aim of this work consists in monitoring the effect caused by the incidence of UV-C light on different bean genotypes using NMR spectroscopy. The genotype samples named IAC Alvorada; TAA Dama; BRS Estilo and BRS Pérola from the Agronomic Institute (IAC; Campinas; SP; Brazil) were evaluated. The following two methodologies were used: a prolonged darkening, in which the grain is placed in a room at a controlled temperature (298 K) and humidity for 90 days, simulating the supermarket shelf; an accelerated darkening, where the grains are exposed to UV-C light (254 nm) for 96 h. The experiments were performed using the following innovative time-domain (TD) NMR approaches: the RK-ROSE pulse sequence; one- and two-dimensional high resolution (HR) NMR experiments (1H; 1H-1H COSY and 1H-13C HSQC); chemometrics tools, such as PLS-DA and heat plots. The results suggest that the observed darkening occurs on the tegument after prolonged (90 days) and accelerated (96 h) conditions. In addition, the results indicate that phenylalanine is the relevant metabolite within this context, being able to participate in the chemical reactions accounted for by the darkening processes. Additionally, it is possible to confirm that a UV-C lamp accelerates oxidative enzymatic reactions and that the NMR methods used were a trustworthy approach to monitor and understand the darkening in bean seeds at metabolite level.

Composite Graphite-Epoxy Electrodes for In Situ Electrochemistry Coupling with High Resolution NMR.

The in situ coupling between electrochemistry and spectrometric techniques can help in the identification and quantification of the compounds produced and consumed during electrochemical reactions. The combination of electrochemistry with nuclear magnetic resonance is quite attractive in this respect, but it has some challenges to be addressed, namely, the reduction in the quality of the NMR signal when the metallic electrodes are placed close to or in the detection region. Since NMR is not a passive technique, the convective effect of the magnetic force (magnetoelectrolysis), which acts by mixing the solution and increasing the mass transport, has to be considered. In seeking to solve the aforementioned problems, we developed a system of miniaturized electrodes inside a 5 mm NMR tube (outer diameter); the working and counter electrodes were prepared with a mixture of graphite powder and epoxy resin. To investigate the performance of the electrodes, the benzoquinone reduction to hydroquinone and the isopropanol oxidation to acetone were monitored. To monitor the alcohol oxidation reaction, the composite graphite-epoxy electrode (CGEE) surface was modified through platinization. The electrode was efficient for in situ monitoring of the aforementioned reactions, when positioned 1 mm above the detection region of the NMR spectrometer. The magnetoelectrolysis effect acts by stirring the solution and increases the reaction rate of the reduction of benzoquinone, because this reaction is limited by mass transport, while no effect on the reaction rate is observed for the isopropanol oxidation reaction.