Real Matrices Research Articles

Exploring Putative Kokumi Oligopeptides in Classic Sparkling Wines with a UHPLC-ESI-MS/MS Targeted Protocol.

Some oligopeptides can impart kokumi flavor to foods and beverages, a topic still not addressed in wine. A targeted ultra-high performance liquid-chromatography-mass spectrometry (UHPLC-MS/MS) metabolomics method capable of quantifying both amino acids and oligopeptides in wines was therefore developed and validated, confirming the presence of 50 oligopeptides in wine, most of which had been previously unexplored. In silico screening of the affinity of these oligopeptides to interact with CaSR, the protein necessary to activate kokumi sensations, highlighted 8 dipeptides and 3 tripeptides as putative kokumi compounds. These compounds were ubiquitous in a representative set of Trentodoc classic method sparkling wines, with an average concentration of kokumi oligopeptides of 19.8 mg/L, ranging between 9.1 and 33.3 mg/L. Half of the sparkling wine samples also contained glutamic acid at concentrations equal to or greater than the threshold for the umami taste in wine, namely, 48 mg/L. Sensory tests on the dipeptide Gly-Val confirmed the ability of this novel kokumi compound to significantly modify the perception of complex real wine matrices but not of the simple model one. Preliminary laboratory-scale fermentation tests showed that the oligopeptide profile in wines is linked to the starting grape matrix and that the patterns change by fermenting barley or apple juice with the same yeast.

From waste to resource: Hydrogen generation and antimicrobial activity of Ag-based photocatalysts recovered from biomedical waste

Electrocardiogram (ECG) disposable electrodes contain a substantial amount of silver (Ag), which can be extracted and recycled. Most current methods for recovering Ag from waste are expensive and environmentally harmful. This study investigated a sustainable chemical process for extracting Ag from discarded medical electrodes using a simple Cu(II) solution under moderately acidic conditions. Using response surface methodology (RSM) based on a three-level, full-factorial design, the optimized extraction conditions were determined as pH = 4.78, T = 80°C, [Cu(II)]₀ = 8.0 × 10⁻³ M, and [NaCl]₀ = 3.72 M. Under these conditions, a process efficiency approaching 100 % was achieved. Moreover, the recovery of metallic silver exceeded 85 %, even when using real matrices. (i.e., discarded ECG electrodes). As a result, the Ag-containing leachate solutions were utilized to synthesize silver-based materials with varying Ag content. These materials demonstrated (i) excellent photocatalytic activity for hydrogen production in aqueous solutions containing organic compounds and (ii) significant antipathogenic properties. In summary, effective Ag/TiO₂ photocatalytic materials with high efficiency for hydrogen production and antimicrobial activity were successfully prepared through a novel, sustainable, and cost-effective chemical recovery process of silver from discarded ECG electrodes.

Peroxydisulfate Activation by Biochar from Banana Peel Promoted with Copper Phosphide for Bisphenol S Degradation in Aqueous Media

In this work, the decomposition of bisphenol S (BPS) by biochar derived from banana peel (BPB) promoted by copper phosphide (Cu3P) was examined. Different materials with Cu3P loadings from 0.25 to 4.00 wt.% on biochar were synthesized, characterized using the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and evaluated. Nearly all of the synthesized materials exhibited low to moderate adsorption capacity, attributable to their limited surface area (<3.1 m2/g). However, in the presence of sodium persulfate (SPS), the 2%Cu3P/ΒPB/SPS system was capable of removing 90% of 500 μg/L BPS in less than 10 min. The system’s performance was enhanced under inherent pH, and the reaction rate followed pseudo-first-order kinetics with respect to BPS and persulfate concentrations. Interestingly, the presence of 250 mg/L of sodium chloride had a negligible effect, while low to moderate inhibition was observed in the presence of bicarbonates and humic acid. In contrast, significant retardation was observed in experiments performed in real matrices, such as secondary effluent (WW) and bottled water (BW). According to scavenging experiments, both radical and non-radical mechanisms participated in the BPS degradation. Four transformation products were identified using the UHPLC/TOF-MS system in negative ionization mode, with two of them having higher molecular weights than BPS, while the other two TBPs involved the ring-opening reaction, and a BPS decomposition pathway was proposed.

Hydrophobic deep eutectic solvent-ferrofluid microextraction followed by liquid chromatography-mass spectrometry for the enantioselective determination of chiral agrochemicals in natural waters.

The increasing use of chiral agrochemicals sold as racemic formulations raises concern for the negative impacts that inactive enantiomers can have on aquatic life and human health. The present work just focuses on the determination of ten chiral pesticides in river water samples by applying a ferrofluid-based microextraction followed by their stereoselective liquid chromatography analysis. To develop the ferrofluid, magnetite nanoparticles were prepared and coated with oleic acid and then dispersed in a hydrophobic natural deep eutectic solvent (NaDES), composed ofL-menthol and thymol (1:1). The stable colloidal dispersion was characterised by scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The analyte microextraction from 5ml river samples was performed using 50µl of ferrofluid, while acidified acetonitrile (150µl) was used to break down the ferrofluid and solubilise the NaDES containing the analytes. All the extracts were analysed by high-performance liquid chromatography-tandem mass spectrometry. For each analyte, the baseline separation of isomers was achieved on a Lux i-Amylose-3 column (amylose tris(3-chloro-5-methylphenylcarbamate) working in reversed-phase mode; the combination with mass spectrometry detection allows the overall separation of 24 isomers (ten chiral analytes among which eight containing a single (one) chiral centre, one with two chiral centres and the last one existing in four stereoisomeric forms, due to the presence of two regioisomers with a chiral carbon) within 37min. The method showed very good figures of merit in terms of recoveries (77.7-97.5%), intra-day and inter-day precision (2.7-7.7% and 6.9-14.9%, respectively), limit of detection (0.01-0.35µg/L), limit of quantitation (0.03-1.20µg/L), linear dynamic range, and intra-day and inter-day accuracy (1.2-14.8% and 1.8-15.0%, respectively). The presented method was able to detect 14 out of 24 isomers at the preventive limit established by the Italian legislation for single pesticide (that for a chiral pesticide is the sum of all its isomers) in surface waters, set at 0.1µg/l. Finally, the method was evaluated using AGREEprep and ComplexGAPI metrics, compared with other ferrofluid-based methods, and applied to the analysis of water samples from two Italian rivers (the Nera River and the Tiber River), providing to be sustainable and reliable for the application to real river matrices.

Reconstruction of a matrix of genotypic correlations between variants within a gene for joint analysis of imputed and sequenced data

When combining imputed and sequenced data in a single gene-based association analysis, the problem of reconstructing genetic correlation matrices arises. It is related to the fact that for a gene, we know the correlations between genotypes of all imputed variants and the correlations between genotypes of all sequenced variants, but we do not know the correlations between genotypes of variants, one of which is imputed and the other is sequenced. To recover these correlations, we propose an efficient method based on maximising the determinant of the matrix. This method has a number of useful properties and has an analytical solution for our task. Approbation of the proposed method was performed by comparing reconstructed and real correlation matrices constructed on individual genotypes from the UK biobank. Comparison of the results of gene-based association analysis performed by the SKAT, BT and PCA methods on reconstructed and real matrices, using modelled summary statistics and calculated summary statistics on real phenotypes, showed high quality of reconstruction and robustness of the method to different gene structures.

Photocatalytic hydrogen production and sulfamerazine degradation via a novel dual S-scheme photocatalyst: Nanocomposite synthesis, characterization and mechanism insights

Creating highly effective photocatalysts is crucial for harnessing solar energy to degrade pollutants and produce hydrogen (H₂). In this study, we successfully synthesized a novel dual S-scheme iron oxide (Fe₂O₃)/bismuth oxide (Bi₂O₃)/titanium dioxide (TiO₂) ternary photocatalyst using a straightforward method. This photocatalyst was employed for efficient photocatalytic water splitting and the degradation of the antibiotic sulfamerazine (SMZ) under visible light. Various characterization and photoelectrochemical techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area analysis (BET), photocurrent measurements, Mott-Schottky analysis, photoluminescence (PL), electrochemical impedance spectroscopy (EIS), and electron spin resonance (ESR), were utilized to analyze the synthesized materials. Among the synthesized nanocomposites, the 15 wt% Fe₂O₃/Bi₂O₃/TiO₂ (15FeBi/TiO₂) composite demonstrated exceptional photocatalytic efficiency, achieving 98 % SMZ degradation and a hydrogen production rate of 590.36 μmol/g·h. Experimental results, including scavenging tests and ESR findings, highlighted the crucial role of hydroxyl radicals (•OH) and superoxide radicals (•O₂−) in the photocatalytic process. Moreover, liquid chromatography-mass spectrometry (LC-MS) results proposed three degradation pathways, and quantitative structure-activity relationship (QSAR) analysis showed that the toxicity of intermediates was effectively reduced. The 15FeBi/TiO₂ photocatalyst also exhibited excellent reusability, retaining about 85 % of its initial activity after five cycles, and proved effective against various pollutants and in real water matrices. This research contributes to the design and development of high-activity heterojunction photocatalysts for superior clean energy generation and pollutant degradation under visible light.

Highlighting the adsorption mechanism of a fluoroquinolone antibiotic from wastewater on carbon xerogel by experiments, characterization, modelling and DFT simulation.

The application of a synthesized carbon xerogel (RFX) for the adsorptive removal from water of ciprofloxacin (CPX), a widely used fluoroquinolones-group antibiotic for humans and animals, has been reported in this work. The carbon xerogel was characterized by N2 adsorption-desorption isotherms, FTIR, Raman spectroscopy, TPD studies, elemental analysis, determination of isoelectric point (pHIEP) and scanning electron microscopy (SEM). CPX adsorption experiments were conducted in batch mode, using results obtained with F400 commercial activated carbon for comparison purposes. CPX adsorption kinetics were well-described by the pseudo-second-order model for both adsorbents and by the Elovich model in the case of F400 activated carbon. Therefore, CPX equilibrium adsorption capacity values were of 457 and 72mgg-1 for RFX xerogel and F400 activated carbon, respectively. This significant difference can be attributed to the higher specific surface area and micropores volume values of F400 carbon; in this sense, this material led to a slower CPX kinetic adsorption. Also, the Dual-site Langmuir model best-described the experimental CPX adsorption isotherms in both cases. By the adsorption studies at different solution pH, it could be concluded that several mechanisms, e.g., hydrophobic and π-π interactions, and electrostatic forces highly influenced CPX adsorption capacity. Furthermore, adsorption tests using several environmentally relevant aqueous matrices have been accomplished. In this case, a competitive effect between the natural organic matter (NOM) and the target pollutant occurred in all the tested real matrices, decreasing CPX adsorption capacity, especially remarkable for F400 activated carbon. Finally, Density Functional Theory (DFT) has been used to elucidate the interactions between CPX and adsorbents, finding a high relevance of the π-π electron donor-acceptor interactions in which CPX acts as an acceptor.

Assessing the Electrochemical Performance of a Novel Low‐Cost Screen‐Printed Electrode Based on Apis mellifera Beeswax Modified with Vulcan@Chitosan Used for Acetominophen Detection

AbstractThe present work reports the development of a highly sensitive electrochemical platform, constructed using screen printed electrode based on Apis mellifera beeswax (SPWE) – employed as substrate, and its application for acetaminophen (AC) detection. The sensor was produced using graphite ink and varnish glass solubilized in acetone. The SPWE was modified with a dispersion of chitosan (0.5% m/v) − functionalized Vulcan XC72R carbon black (Vulcan@Chitosan). Electrochemical characterization was performed using cyclic voltammetry (−0.7 to +0.8 V vs. pseudo‐graphite) and chronoamperometry in 0.1 mol L−1 KCl in the presence of 1.0 mmol L−1 [Fe(CN)6]3−/[Fe(CN)6]4−. Through the application of differential pulse voltammetry (DPV) using 0.1 mol L−1 PBS at pH 6.5, the proposed SPWE/Vulcan@Chitosan sensor was found to exhibit significant improvements in current response relative to the AC electrochemical detection. The sensor exhibited linear dynamic range of 0.05 to 4.0 μmol L−1 (n= 3), with R2= 0.992 and theorical LOD of 0.013 μmol L−1 (RSD= 3.80%). The AC detection was conducted in real matrices of river water, synthetic urine and synthetic saliva using the DPV technique yielded a mean recovery rate of 103% (RSD= 3.52%), exhibiting a high degree of accuracy. The SPWE/Vulcan@Chitosan electrochemical platform demonstrated high stability, good reproducibility and satisfactory repeatability; the current responses were not affected by the reutilization of the beeswax substrate for the production of new electrode. The findings of this study show that the proposed modified electrode is a simple, low‐cost sensing device which has proven to be highly efficient when applied for the AC detection in different matrices.

Complete Asymptotic Expansions for the Normalizing Constants of High-Dimensional Matrix Bingham and Matrix Langevin Distributions

For positive integers $d$ and $p$ such that $d \ge p$, let $\mathbb{R}^{d \times p}$ denote the set of $d \times p$ real matrices, $I_p$ be the identity matrix of order $p$, and $V_{d,p} = \{x \in \mathbb{R}^{d \times p} \mid x'x = I_p\}$ be the Stiefel manifold in $\mathbb{R}^{d \times p}$. Complete asymptotic expansions as $d \to \infty$ are obtained for the normalizing constants of the matrix Bingham and matrix Langevin probability distributions on $V_{d,p}$. The accuracy of each truncated expansion is strictly increasing in $d$; also, for sufficiently large $d$, the accuracy is strictly increasing in $m$, the number of terms in the truncated expansion. Lower bounds are obtained for the truncated expansions when the matrix parameters of the matrix Bingham distribution are positive definite and when the matrix parameter of the matrix Langevin distribution is of full rank. These results are applied to obtain the rates of convergence of the asymptotic expansions as both $d \to \infty$ and $p \to \infty$. Values of $d$ and $p$ arising in numerous data sets are used to illustrate the rate of convergence of the truncated approximations as $d$ or $m$ increases. These results extend recently-obtained asymptotic expansions for the normalizing constants of the high-dimensional Bingham distributions.

Efficient Electrocatalytic Hydrodechlorination and Detoxification of Chlorophenols by Palladium-Palladium Oxide Heterostructure.

Electrocatalytic hydrodechlorination is a promising approach for simultaneous pollutant purification and valorization. However, the lack of electrocatalysts with high catalytic activity and selectivity limits its application. Here, we propose a palladium-palladium oxide (Pd-PdO) heterostructure for efficient electrocatalytic hydrodechlorination of recalcitrant chlorophenols and selective formation of phenol with superior Pd-mass activity (1.35 min-1 mgPd-1), which is 4.4 times of commercial Pd/C and about 10-100 times of reported Pd-based catalysts. The Pd-PdO heterostructure is stable in real water matrices and achieves selective phenol recovery (>99%) from the chlorophenol mixture and efficient detoxification along chlorophenol removal. Experimental results and computational modeling reveal that the adsorption/desorption behaviors of zerovalent Pd and PdO sites in the Pd-PdO heterostructure are optimized and a synergy is realized to promote atomic hydrogen (H*) generation, transfer, and utilization: H* is efficiently generated at zerovalent Pd sites, transferred to PdO sites, and eventually consumed in the dechlorination reaction at PdO sites. This work provides a promising strategy to realize the synergy of Pd with different valence states in the metal-metal oxide heterostructure for simultaneous decontamination, detoxification, and resource recovery from halogenated organic pollutants.

Catalytic hydrodehalogenation of iodinated contrast agents in drinking water: A kinetic study

The occurrence of iodinated contrast media (ICM) in water bodies represents a significant threat for public health due to their strong biochemical stability and recalcitrance to conventional water treatment systems. In this work, the feasibility of catalytic hydrodehalogenation (HDH) for the degradation of a representative group of ICMs (iohexol (IHX), iopromide (IPR), iopamidol (IPM) and diatrizoic acid (DIA)) is investigated. Complete degradation and deiodination of the isolated ICMs (1.6·10−2 mmol L−1) was achieved in less than 30 min in the presence of 0.25 g L−1 of different precious metal catalysts (Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3) under ambient conditions, closing iodine balance by >95 %. Based on the identified reaction intermediates and final products, reaction mechanisms were accordingly proposed. A sequential reaction pathway was proposed for DIA removal, while reaction mechanisms encompassing both sequential and concerted reaction steps were proposed for the non-ionic ICMs (IHX, IPR, and IPM). Subsequent kinetic models, which successfully described experimental data, were developed from the elucidated reaction mechanisms, considering all species involved in the reaction. The versatility of the process was finally demonstrated in the treatment of real aqueous matrices (surface water and tap water) spiked with the ICMs mixture, except in the case of Pt/Al2O3 which suffered deactivation due to surface poisoning by halides. For this catalyst, kinetic constants ranged from 0.31 to 0.22 min−1 in deionized water, and from 0.04 to 0.08 min−1 in surface water as the reaction matrix. Among the tested catalysts, Pd/Al2O3 showed the highest activity and stability for the removal of ICMs.

Bi-monotone maps on the set of all variance-covariance matrices with respect to minus partial order

Let Hn+(R) be the cone of all positive semidefinite n×n real matrices. We describe the form of all surjective maps on Hn+(R), n≥3, that preserve the minus partial order in both directions.

Photo-Fenton-like activity of Fe/ZnO structure applied as a heterogeneous catalyst for the methylene blue dye removal in aqueous matrices

This work developed efficient heterogeneous catalysts for the methylene blue (MB) dye degradation under photo-Fenton-like conditions. The material was modified to incorporate Fe(III) into ZnO, creating Fe/ZnO strucuture, and applied as heterogeneous catalysts at various pH levels. SEM analysis revealed an agglomerated and plate-like morphology of the synthesized catalysts. The enhanced structure facilitated a removal efficiency of 96.2% for MB dye when employing the photo-Fenton-based process using 5.0% Fe/ZnO catalyst. The high removal efficiency is attributed to the synergy between ≡Fe(III) and ≡Zn(II), which promotes the generation of photoradical species through the Fenton effect. Real water matrices served as a source of MB dye contamination, exhibiting minimal interference and achieving ∼100 % of removal. Scavenger studies indicate that •OH and e⁻ are the primary contributors to the high MB dye degradation efficiency. Additionally, the by-products formed after photo-Fenton process exhibit minimal toxicity towards Lactuca sativa L. No Fe(II) ions were leached at the end of the process. Eight cycles of degradation did not cause significant spectral changes in the FTIR analysis, as well as in the XRD patterns, indicating the material efficient and stable structure.

Proton conductive 2D MXene-derived potassium titanate nanoribbons fabricated electrochemical platform for trace detection of enrofloxacin

In recent years, due to exceptional properties like broad interlayered spacing and low working potential, MXene-derived titanate nanoribbons have been established as promising electrode materials. Herein, the electrocatalytic activity of MXene-derived potassium titanate nanoribbon was employed to develop a voltammetric sensor for the detection of enrofloxacin. The sensor's significance is to provide a sustainable solution to quantify the presence of enrofloxacin regarding food safety and environmental monitoring. Moreover, to achieve the United Nations' Sustainable Development Goals by preventing antimicrobial resistance to accomplish the One Health approach. Potassium titanate nanoribbons were synthesized using 2D Ti3C2 MXene as an active precursor material, while X-ray diffraction spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction pattern, elemental mapping, and energy-dispersive X-ray spectroscopy were used to characterize the crystallinity, surface and layered morphology of synthesized nanoribbons. The Brunauer-Emmett-Teller (BET) technique was applied to calculate the specific surface area of the synthesized materials. The materials underwent electrochemical characterization using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Later on, the nanoribbons were fabricated on the surface of a glassy carbon electrode, and the electro-oxidative behaviour of enrofloxacin was studied by CV, DPV, square wave voltammetry (SWV) in 0.1 M phosphate buffer (optimized pH 8). The developed sensor depicts a significantly lower limit of quantification of 0.007 μM (≈2.5 μg/L), and an upper limit of quantification of 18 μM (≈6.5 mg/L) along with a limit of detection (LOD) of 0.00279, 0.00803, 0.00881 μM obtained from CV, DPV, and SWV respectively. Furthermore, the developed electrodes show a reliable selectivity to be examined in real complex matrices, i.e. marine water, river water, agricultural soil, organic fertilizer, milk, honey, and poultry egg.

Molecular insights into pilot-scale selective removal of emerging contaminants in hospital wastewater

Advanced oxidation processes (AOPs) are a promising technology for removing emerging organic contaminants (EOCs) from wastewater, while the coexisting dissolved organic matter (DOM) significantly hinders effective oxidative removal of EOCs. Understanding the effects of DOM on EOCs removal in real water matrices is crucial for designing more efficient AOPs. Herein, a pilot-scale integrated in-situ ozonation/ultrafiltration process was conducted to remove EOCs from hospital wastewater. Furthermore, the ozonation reactivity of DOM and EOCs was contrastingly analyzed at the molecular level. Our integrated process selectively removed 85 % of EOCs at a relatively low oxidant dosage of 0.44 mg O3 per mg dissolved organic carbon (DOC). Using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), we reveal that ozone selectivity for EOCs arose from their overall reductive characteristics of being more aromatic and unsaturated in molecular composition compared to DOM. Additionally, specific DOM compounds potentially facilitate EOCs removal. This work provides pilot-scale experience in EOCs removal from hospital wastewater and in-depth understanding of DOM’s role in the integrated process, guiding the development of effective AOPs for selective removal of emerging contaminants.

An S-Scheme CeO2/Bi2O2S heterojunction photoanode for the photoelectrocatalytic degradation of sulfamethoxazole in synthetic and real wastewater

We prepared an S- scheme heterojunction photoanode using cerium oxide (CeO2) and bismuth oxysulfide (Bi2O2S) for the photoelectrocatalytic degradation of sulfamethoxazole. The CeO2 /Bi2O2S photoanode was synthesised via an in-situ hydrothermal method, ensuring strong contact and efficient charge transfer between the CeO2 and Bi2O2S. The materials and photoanode were characterized with XRD, XPS, photoluminescence, and photoelectrochemistry. The S-scheme configuration observed in the formation of heterojunction in CeO2 /Bi2O2S photoanode was responsible for the improved photoelectrocatalytic performance for the visible light-assisted degradation of sulfamethoxazole. Operational parameters such as the effect of pH and current density were examined. The extent of sulfamethoxazole mineralisation was calculated to be 72 % using the total organic carbon (TOC) measurement. The LC-MS analysis was used to predict the degradation pathway and products. Furthermore, the photoelectrocatalytic efficiency of the CeO2/Bi2O2S photoanode was investigated in real wastewater matrices with TOC removal of 54 %. Therefore, the S scheme CeO2/Bi2O2S photoanodes lends itself to photoelectrochemical water treatment applications.

The exact solution of the Wegner flow equation with the Mielke generator for 3 × 3 hermitian matrices

The Wegner flow equation is a differential equation for a family of Hamiltonians and can be considered as a continuous unitary transformation. In essence, the transformation continuously decouples degrees of freedom and gradually converts the transformed Hamiltonian into the near-diagonal form. The Wegner flow equation has so far been applied to many areas of physics, but mainly in perturbative calculations. However, the exact solutions are known only for the simplest of two-dimensional case and this certainly limits the practical application of the method. On the other hand, the knowledge of exact solutions is essential for many physical problems as well as it can help in constructing improved approximated approaches. In this paper we present the exact solution of the Wegner flow equation with the Mielke generator for 3 × 3 Hermitian matrices, the general solutions for N × N tridiagonal Hermitian matrices and partially for 4 × 4 real symmetric matrices.

The role of processing on phenolic bioaccessibility and antioxidant capacity of apple derivatives

Fruit derivatives are commonly obtained by applying processing operations deemed responsible for the loss of phenol compounds, but very little information is available on the fate of phenols upon digestion of these products. The present study evaluated the effect of thermal and mechanical treatments, commonly applied to turn apple pulp into puree and homogenate, on phenolic bioaccessibility and antioxidant activity.Despite a 20 % decrease in polyphenols due to processing, their bioaccessibility was higher in apple derivatives (>20 %) compared to pulp (∼2 %). Polyphenol oxidase (PPO), inactivated by thermal treatments in apple derivatives but not in the pulp, was hypothesized to be responsible for this difference. Results acquired on an unprocessed PPO-free apple model, only featuring quercetin-3-glucoside and pectin, actually exhibited similar bioaccessibility as processed derivatives.The radical scavenging capacity was unaffected by the structural integrity of apples, indicating independence from the plant tissue's hierarchical arrangement. After digestion, radical scavenging capacity decreased in the real apple matrices, correlating with phenolic content, while it was retained in the apple model, further suggesting the pivotal food matrix role in modulating polyphenols bioaccessibility and subsequent biological activity.Translating these results to an industrial scale, processing conditions can be optimized not only to guarantee that the quality requirements are met, but also to achieve desired nutritional benefits.

Some new facts about linear maps that preserve the orthogonal group

In this article, Albert Wei's result which described the forms of the linear maps that preserve the set of orthogonal matrices is treated and its new proof is provided. Wei's result is simplified by introducing a new description of the singular linear maps acting into the space n by n real matrices that preserve orthogonal matrices. From this description, one can immediately conclude that the range of such singular maps is isometrically isomorphic with the space R n . The proof of the Wei's result that is presented here is based on many new facts about linear maps that preserve the orthogonal group of matrices that are of interest independently of issues considered here.

A silicon-based functional self-assembled aptasensor for the detection of aflatoxin B1 by SERS sensing.

One of the most harmful contaminants found in corn and its products is aflatoxin B1 (AFB1) and thus developing reliable detection methods is of great significance to consumers and the food industry. In this research, AuMBA@Ag nanoparticles (NPs) and AgNPs deposited on a silicon wafer (Si@AgNPs) were functionalized with an aptamer and its complementary strand, respectively, and self-assembled into a SERS aptasensor, which generated strong SERS signals. AFB1 bound to the aptamer prior to the complementary chain, causing AuMBA@Ag NPs to detach from Si@AgNPs. The complex dissociated, leading to a decrease in signal intensity from the solid-phase substrate. Under optimal conditions, the linear detection range was 0.05-20.0 ng mL-1, and the detection limit was 0.039 ng mL-1. Notably, the aptasensor demonstrated a recovery rate between 92.77% and 110.13% when utilized for the detection of AFB1 in corn flour and oil, indicating its good potential for detecting AFB1 in real sample matrices. In conclusion, a quantitative and reliable specific SERS detection system for AFB1 was developed in this study with significant applicability to food safety.