Oxidative stress increases with aging and may influence both sleep physiology and gut microbial activity. Molecular hydrogen, produced by intestinal fermentation, acts as an endogenous antioxidant and can be measured noninvasively in exhaled breath. However, age- and sex-related differences in nocturnal changes of breath hydrogen remain unclear.
We analyzed breath hydrogen and methane levels in 166 healthy adults aged 20-85 years. Participants self-collected end-alveolar breath samples at home before sleep and immediately after waking. Breath hydrogen and methane levels were determined by gas chromatography. 
The older group (n = 91) showed significantly lower breath hydrogen levels after waking compared with the non-older group (n = 75), despite no differences before sleep. No significant sex-related differences were observed. The older group also reported more frequent nocturnal awakenings. These findings suggest that age-related changes in hydrogen dynamics may be associated with sleep-related physiological processes. The overnight change in breath hydrogen was significantly greater in the older group compared with the non-older group, indicating a larger overnight reduction in hydrogen levels in older adults. No significant differences in breath methane levels were observed between groups.
Age-related alterations in gut microbiota, gastrointestinal motility, and redox balance may contribute to reduced morning hydrogen levels. Breath hydrogen measurement represents a simple, noninvasive biomarker for assessing physiological changes associated with aging and sleep.
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The experimental discovery of high Tcsuperconductivity in sulfur and lanthanum hydrides under extreme pressure has fueled the search for superconductivity at, and potentially beyond, room temperature in superhydrides. In the years that followed, the field has seen both rapid scientific progress and scrutiny, particularly following the retraction of several high-profile claims. This mini review attempts to provide a balanced overview of the progress made, challenges encountered, and opportunities presented that continue to reshape the research on superhydrides. This scrutiny has increased emphasis on experimental standards and scientific rigor. Emerging techniques, such as local quantum sensing, which is capable of spatially resolving magnetic responses, have provided more direct measurements of the Meissner effect, helping to address earlier verification controversies. On the theory front, predictions of new hydrides have shifted from binary toward ternary and higher systems, enabled by new tools such as high-throughput crystal structure prediction and machine-learning-accelerated screening. The enhanced exploration of compositional spaces has revealed new structural motifs, such as the 'alloy backbone', which utilizes a light-element subnetwork to provide additional precompression, revealing a pathway to stabilizing hydrogen-rich frameworks at reduced pressures. Concurrently, new ideas such as the fluxional hydrogen lattice, where electron-phonon coupling extends beyond involving only harmonic phonons to include collective excitations of a diffusive hydrogen sublattice, are refining the understanding of conventional superconductivity under extreme conditions. This mini review highlights representative developments along the way and organizes them within a chronicle of scientific advances. It concludes with a summary and discussion of key challenges and a perspective on the feasibility of ambient-condition superconductivity. More broadly, theoretical and experimental methodologies developed in the study of superhydrides are increasingly influencing materials discovery across condensed matter physics, extending well beyond the immediate pursuit of superconductivity under pressure.
The industrial application of proton exchange membrane electrolysis for hydrogen production urgently requires acidic hydrogen evolution reaction (HER) catalysts that combine high activity with long lifespan at ampere-level current densities. This work employs electrochemically driven dynamic reconstruction to in situ transform self-supporting Cu3P nanowires into a core-shell structure with a loose surface layer consisting of PtCu/Cu3P heterostructures. The reconstructed catalyst exhibits benchmark HER performance in acid, requiring low overpotentials of only 37.8 and 207.8 mV at 10 and 1000 mA cm-2, respectively, while maintaining stable operation for over 240 h at 1000 mA cm-2. Mechanistic studies reveal that the heterointerface synergistically regulates hydrogen adsorption free energy and facilitates proton transport, while the loosely porous morphology formed by reconstruction ensures efficient mass transfer at high currents. The catalyst's exceptional durability stems from the dynamic dissolution-redeposition equilibrium of surface metal species during operation. This work reveals a novel reconstruction pathway in acid involving foreign metal participation, enabling industrial-scale acidic HER catalysis.
Vascular plants require boron to cross-link the rhamnogalacturonan-II (RG-II) domain of pectin to form functional cell walls. Boronic acids, which form reversible esters with cis-diols like borate, have been proposed to influence RG-II cross-linking, though the mechanism remains unclear. We used suspension-cultured rose cells adapted to grow without boron to investigate the effect of boronic acids on RG-II dimerization. When grown with phenylboronic acid (PBA) as the sole boron source, nearly all RG-II was crosslinked, whereas methylboronic acid (MBA) only partially restored cross-linking. In contrast, in vitro assays showed that homogeneous RG-II monomers did not dimerize with alkyl or aryl boronic acids unless supplemented with hydrogen peroxide (H₂O₂), which oxidatively converts boronic acids to boric acid. Real-time NMR spectroscopy and density functional theory calculations provided insight into the reaction mechanism and energetics of oxidation respectively. Together, our data show that exogenous boronic acids are a source of boric acid for plants, and that the deboronation reaction generates aryl or alkyl alcohol byproducts that can undergo further chemical modification in planta. The fate and potential roles of these byproducts in planta remain to be determined.
Two-dimensional (2D) transition-metal dichalcogenides are promising channel materials, but integrating ultrathin high-k gate dielectrics remains challenging because their surfaces lack dangling bonds. Atomic layer deposition (ALD) enables conformal dielectric growth on these 2D materials, with oxidant selection introducing a trade-off between water (H2O), which yields poor nucleation, and ozone (O3), which affords uniform coverage at the expense of interface/channel degradation via oxygen substitution. Here, we demonstrate that hydrogen peroxide (H2O2)-driven ALD of high-k oxides yields uniform dielectric coverage while minimizing performance degradation by controlling Mo-sulfate formation at the interface on molybdenum disulfide (MoS2). This chemistry offers nucleation sites while preserving the 2D channel integrity through S-O interfacial bonding. Top-gated MoS2 field-effect transistors (FETs) with H2O2-based ALD hafnium oxide (HfO2) gate dielectrics achieve steep subthreshold slopes (∼70 mV/dec), low hysteresis (∼42 mV), and an equivalent oxide thickness (EOT) of ∼0.9 nm. Benchmarking shows that these devices exhibit improved performance compared with previously reported single-dielectric top-gated MoS2 FETs. These findings establish H2O2-driven ALD of a high-k dielectric as a promising approach for complementary metal-oxide-semiconductor (CMOS)-compatible 2D gate stacks and suggest that robust S-O interfacial bonding can enable 3D-integrated, low-power device operation.
Metal-organic frameworks with coordinatively unsaturated metal sites (open metal sites) capable of engaging in orbital interactions with π-acidic gases are of interest for enabling ambient-temperature gas separations, such as hydrogen isotope separations. In view of the weakly π-acidic nature of H2, we sought to strengthen π-backbonding-mediated H2 adsorption through pore confinement effects. Toward that end, we synthesized and characterized the ultramicroporous metal-organic framework CuxZn5-xCl4-yHz(bbta)3 (CuIZn-MFU-4; H2bbta = 1H,5H-benzo(1,2-d:4,5-d')bistriazole), featuring π-basic trigonal pyramidal CuI sites that reside within 7 Å of one another at their closest. Gas adsorption measurements reveal an H2 adsorption enthalpy of -38 kJ/mol, exceeding that of the larger-pore analog (CuIZn-MFU-4l; -33 kJ/mol) and representing the strongest H2 adsorption yet achieved in a metal-organic framework. The stronger H2 adsorption in CuIZn-MFU-4 is attributed to a combination of pore confinement effects and the increased σ-accepting nature of the CuI sites caused by a more electron-withdrawing bbta2- linker, as supported by structural, spectroscopic, and computational evidence. With the strongest H2 adsorption, equilibrium isotope effects in CuIZn-MFU-4 lead to a D2/H2 selectivity (as estimated by ideal adsorbed solution theory) of 1.35 even at 298 K, approaching the values reported below 200 K for conventional porous materials.
Display technologies require optical adhesives that simultaneously provide high optical clarity, refractive index control, low birefringence and adhesive strength. However, many commercial adhesive systems rely on petroleum-derived acrylates and isocyanate-based urethanes. Herein, a fully biobased optical adhesive is reported that exploits the initiator-free photopolymerization of dithiolanes. Furthermore, hydrogen bond strength is modulated within the prepared adhesives by changing the chemistry with which the dithiolane is conjugated to a macromolecular core, allowing manipulation of properties including glass transition temperature, adhesion, refractive index, and other optical properties. Throughout these variations, all materials maintain high optical performance, exhibiting visible light transmittance above 98% and haze below 0.7%, coupled with low optical dispersion. These results demonstrate that dithiolanes are readily applied as initiator-free crosslinkers for the formulation of fully biobased optical adhesives.
Hydrogenotrophic methanogens are anaerobic archaea that convert carbon dioxide and hydrogen into methane. Central to this process is the heterodisulfide reductase (Hdr), which catalyzes the reduction of the heterodisulfide made of coenzyme M and coenzyme B. In vivo, Hdr functions in association with electron-donating modules such as the [NiFe]-hydrogenase (HdrMvh), which supplies reducing equivalents derived from hydrogen oxidation. Here, we isolate the catalytic properties of Hdr by evaluating substrate turnover independently of its native electron-donating modules using an artificial electron donor system. The molecular features governing substrate recognition and turnover by Hdr were investigated through the design and synthesis of 18 non-endogenous analogs of the native heterodisulfide substrate (compounds 2a-r). We show that several non-endogenous disulfides can serve as alternative substrates for Hdr, including analogs with variation in the coenzyme B-derived amino acid moiety (O-phosphono-Ser, L-Asp, L-Glu, and 2-aminoadipic acid), and that the coenzyme M sulfonate can be replaced by a carboxylate group. In contrast, modifications that disrupt charge balance, chain length, or stereochemical compatibility result in loss of substrate activity and, in some cases, lead to inhibitory behavior, underscoring the narrow constraints required for productive catalysis.
Macropinocytosis serves as the primary pathway for nanomaterials to enter cells. However, the dynamic processes and physical chemistry mechanisms underlying this phenomenon remain poorly understood. Here, we reveal that the uptake of nanoclay (kaolinite) into cells is predominantly influenced by biointerface structural effects, with the formation of a dynamic hydrogen-bond network at the interface playing a pivotal role. Kaolinite samples of varying sizes were obtained through centrifugal fractionation. We systematically compared interactions between kaolinite of different sizes and the same cell type, as well as between kaolinite of identical size and different cell types. Both cellular experiments and molecular dynamics simulations confirmed that the dynamic hydrogen-bond network at the interface regulates macropinocytosis, a process jointly influenced by material size and membrane composition. This study elucidates the dominant role of hydrogen bonds at the nanoclay/cell membrane interface during macropinocytosis, providing a physical chemistry perspective for its regulation.
The propargyl radical (C3H3) is the simplest resonance-stabilized free radical (RSFR), but how does stepwise methyl substitution in the alkene reactant affect its dynamics of their formation? We report a crossed molecular beam study of the reactions of atomic carbon (C, 3Pj) with four butene isomers (C4H8) under single-collision conditions at a collision energy of 28 ± 2 kJ mol-1. Barrierless addition of atomic carbon to the alkene C═C bond triggers ring opening to substituted triplet allenes─a de facto insertion mechanism─followed by unimolecular decomposition via atomic hydrogen (H), methyl (CH3), or ethyl (C2H5) loss, yielding a family of propargyl-type RSFRs. RRKM calculations reveal that the branching ratios are highly sensitive to the alkene structure. While the methyl loss channel, affording 1-methylpropargyl, dominates for 2-butenes (80-90%), the predicted hydrogen-atom loss channel (≈10%), leading to 1,3-dimethylpropargyl is identified experimentally by comparison with theoretical energetics. For isobutene, near-equal competition is observed, with the reaction producing 3-methylpropargyl (≈50%) and 1,1-dimethylpropargyl (≈40%), along with 2-vinylallyl (≈5%), whose formation is supported by experimental data. Most notably, the reaction with 1-butene uniquely favors an enthalpically driven hydrogen shift, eventually producing 1-vinylallyl (≈38%), which is assigned based on the excellent agreement between the measured and calculated reaction exothermicity. Rapid entropically favored fragmentation channels yield ≈40% of propargyl-type species (propargyl, 1- and 3-ethylpropargyls), slightly outcompeting the allyl-type product. These results establish a systematic progression from C2H4 via C3H6 to C4H8, where the increasing alkyl substitution unlocks new fragmentation channels, providing a versatile gas-phase route to alkylated RSFRs─key intermediates in the growth of methylated and ethylated PAHs and aliphatic chains in combustion and cold interstellar environments (molecular clouds).
The development of electrocatalysts that maintain high efficiency and durability at industrial current densities remains a pivotal challenge for alkaline water electrolysis. Here, we present a high-performance phosphide-modified multimetallic hydrogen evolution reaction (HER) catalyst, NiFe0.33RuOx@P, with high-current-tolerant and low noble-metal content. In this catalyst, Ni and Fe mainly exist as phosphide-derived species with partial surface oxidation, while Ru is predominantly present as RuP-like active domains embedded in the multimetallic matrix. The electrolyzer with a Ni foam anode and NiFe0.33RuOx@P cathode delivers an exceptional current density of 1.7 A cm-2 at 2.0 V under 6 M KOH (≈ 30%) at 70°C, demonstrating outstanding industrial-level performance. This catalyst requires an overpotential of only 72 mV to achieve 100 mA cm-2 for HER in 1 M KOH, lower than commercial Pt/C. Critically, it sustains stable operation for over 200 h in 6.0 M KOH at 500 mA cm-2. Scalability is confirmed on a 25 cm2 electrode, underscoring its practical potential. The exceptional stability and activity are rooted in a phosphorus-tuned electronic structure that yields a near-optimal hydrogen adsorption free energy (ΔGH* tuned from +0.498 to -0.153 eV).
Dihydroorotate dehydrogenase (DHODH), an important enzyme in de-novo pyrimidine synthesis, and its dysregulation has been frequently associated with various diseases including cancer. Extensive evidence indicates that the inhibition of DHODH can efficiently induce apoptosis in tumor cells. Although well-known inhibitors like teriflunomide, leflunomide and brequinar have been investigated, their clinical utility is shown to be limited due to poor bioavailability and moderate efficacy in trials. This emphasizes the necessity for the development of potent and non-toxic drug-like candidates targeting DHODH enzyme. Recently, plant-derived compounds offer significant advantage due to their potential of reducing adverse effects compared to synthetic drugs. Thus, we screened a total of 1,574 anticancer phytocompounds curated in the NPACT database for their potential inhibitory activity against DHODH. Compounds exhibits favorable pharmacokinetic properties were subjected to a structure-based molecular docking approach and MM-GBSA validation. Importantly, empirical and deep learning algorithms such as Gnina, Kdeep, Vinardo, Smina and X-Score were utilized for validating the compounds activity. Collective evidence highlights that NPACT00730 showed the strongest interactions with the crucial residues such as GLN47, ARG136 and TYR356 of DHODH. Additionally, scaffold analysis revealed that the chalcone moiety present in hit compound is well established with anticancer activity across multiple cancer cell lines. In the end, the results were further supported by membrane simulations for 100ns, followed by solution-based simulation to evaluate the stability of the protein-ligand complex. The parameters such as RMSD, RMSF, Rg, Hydrogen bonds, SASA, Principal component analysis (PCA) and free energy landscape (FEL) were analyzed. Overall, we hypothesize that NPACT00730 has inhibitory activity against DHODH and represents a computationally prioritized DHODH inhibitor candidate exhibiting predicted multi-cell-line anticancer sensitivity, warranting further experimental validation.
Cellulose microfibrils (CMFs) in wood macrofibrils are semi-crystalline including crystalline and disordered regions, yet the mechanical role of disordered cellulose remains elusive. Here, we employed reactive molecular dynamics simulations to systematically investigate the mechanical role of disordered cellulose by developing atomic models of softwood macrofibrils with varying cellulose crystallinity. Simulation results showed that there is a critical balance between the strength and toughness of macrofibrils governed by the cellulose crystallinity. Lowering cellulose crystallinity decreased the longitudinal modulus and tensile strength of macrofibrils but increased the ultimate strain. In contrast, toughness exhibited a non-monotonic dependence on crystallinity and reached a peak at approximately 90%. Hydrogen-bond analysis revealed that disordered cellulose mainly led to fewer hydrogen bonds within CMFs, thereby weakening the strength of macrofibrils. Fracture analysis further revealed that disordered regions acted as crack initiation points and energy dissipation regions, making macrofibrils exhibit more ductile behavior. In addition, a theoretical model based on mixture rule incorporating the effect of interphase was proposed to predict the longitudinal moduli of macrofibrils. These findings provide fundamental molecular insights into the structure-property relationships of macrofibrils in wood secondary cell walls and shed light on the design of wood-based materials with tailored mechanical properties.
Cellulose-based nanomaterials have potential to act as renewable and versatile additives for tailoring properties of aqueous surfactant systems. This study compares the effect of negatively charged cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and their molecular counterpart, carboxymethylcellulose (CMC), on the rheological properties and microstructural organization of aqueous aggregates of cationic di(hydrogenated tallow) dimethylammonium chloride. Their lamellar phases can be assumed as representative of those found in cosmetics, fabric softeners, and related formulations. Samples were prepared with an excess of cationic surfactant relative to the anionic additives while maintaining a constant surfactant/additive mass ratio for both surfactant concentrations. The surfactant was slowly added to pre-existing (nano)cellulose suspensions or solutions, allowing lamellar phase formation to occur in the presence of nanoparticles or polymer chains. Rheological measurements were performed alongside differential scanning calorimetry, small- and wide-angle X-ray scattering experiments. The rigidity and yield stress of the samples depend on the type of additive (CNC, CNF, or CMC) and the surfactant/additive ratio. With CNC, these properties increase with concentration, reaching a maximum at a surfactant/additive ratio of 100 (0.05 and 0.1 wt% CNC for 5 and 10 wt% surfactant, respectively), and then decrease at higher additive contents. The rheological behavior is closely linked to changes in lamellar organization, including variations in bilayer repeat distance and the coexistence of multiple lamellar phases in samples with CMC. These findings reveal the general colloidal outcome of hybrid oppositely charged lamellar-particle networks in aqueous surfactant systems, opening new opportunities for exploiting cellulose nanomaterials in concentrated surfactant formulations.
Embedding π-conjugated units into peptide backbones enables control over π-π interactions and promotes energy transfer within fibrillar nanostructures resembling those formed from natural β-sheet-rich proteins. As a result, peptide sequences that naturally form or favor β-sheet architectures are commonly used in the construction of these systems. Most amino acid residues generally promote the formation of β-sheet structures; however, proline is usually viewed as a β-blocker that favors more helical structures. Consequently, our previous π-peptide studies excluded proline-containing sequences. In this study, we investigate how the incorporation of proline into π-peptides identified computationally for its ability to foster strong intermolecular electronic coupling affects the electronic and structural behavior of the resulting π -conjugated peptide nanostructures. Despite the expectation that proline would disrupt β-sheet organization, simulations and cryo-EM studies suggest that curved conformations of the π-peptide can still foster the formation of hydrogen-bonding and π-stacked assemblies. Using UV-vis, PL, and CD spectroscopies, we explore how proline's structure and stereochemistry (D/L form) influence the photophysical properties and supramolecular chirality of these assemblies.
This double-blind and split-mouth randomized controlled trial evaluated color change progression in non-carious cervical lesions (NCCLs) restored with one-shade or multi-shade resin composites following in-office dental bleaching. Eighty-four NCCLs were restored using one-shade (Vittra Unique, FGM) or multi-shade (Vittra APS, FGM) resin composites (n = 42). Each participant received two restorations (one per hemiarch). Afterward, two sessions of in-office bleaching with 35% hydrogen peroxide were performed. Color progression was assessed using WID, ΔEab, and ΔE00 at baseline, after each bleaching session, and one-month post-bleaching. Color matching between the cervical (restoration) and middle (adjacent tooth structure) thirds was also evaluated. Secondary outcomes included tooth sensitivity, and clinical performance according to FDI criteria. Data were analyzed using paired t-tests, linear mixed models, and McNemar test (α = 0.05). In the middle third, no differences between materials were observed for any color parameter (p > 0.05). In the cervical third, the one-shade composite showed higher WID values over time than the multi-shade composite (p < 0.05), whereas no differences were observed for ΔEab or ΔE00 progression (p > 0.05). After one month, the multi-shade composite showed greater color mismatch than the one-shade composite (p < 0.05). Tooth sensitivity did not differ between groups (p = 1.00). All restorations were classified as clinically very good according to FDI criteria. The one-shade composite showed greater whitening progression in the restored cervical area and lower color mismatch after bleaching, while both materials presented similar short-term clinical performance and participant-related outcomes. Single-shade composite may promote greater short-term whitening progression in the restored cervical area and improved color matching performance after in-office bleaching compared with multi-shade composites in NCCLs. Clinically, this may support minimally invasive approaches by reducing the need for restoration replacement and preserving tooth structure.
Molecular simulation with an ab initio-based intermolecular potential is used to investigate the atomic-level interactions responsible for the thermodynamic properties and vapor-liquid-equilibria (VLE) of deuterium (D2). Results are reported for pressures up to 100 MPa at both low (cryogenic) and ambient temperatures. The combination of a simplified ab initio atomic potential (SAAP) with Feynman-Hibbs first order (FH1) interactions closely reproduces the VLE phase envelope over a wide range of densities, resulting in good estimates of the critical properties. It also accurately reproduces the behavior of the second virial coefficient and pressure-temperature-volume properties. The analysis indicates that deuterium and hydrogen share the same intermolecular potential, i.e., SAAP(H2) + FH1. Additional quantum corrections to the kinetic energy (QCKE) are used to determine the enthalpy, heat capacities, isochoric pressure coefficient, isobaric thermal expansion coefficient, Joule-Thomson coefficient and the speed of sound. At cryogenic conditions, using QCKE yields close agreement with reference values for these properties.
Uric acid, the final product of purine metabolism in humans, accumulates in blood and tissues at relatively high concentrations 1 as humans lack the enzyme uricase 2,3 . Under inflammatory conditions, uric acid can be oxidised to yield reactive intermediates 4 . In activated neutrophils, myeloperoxidase (MPO) catalyses the oxidation of uric acid by hydrogen peroxide, leading to the formation of urate hydroperoxide (UH) 5,6 . While recent studies have shown that UH is toxic to bacteria lacking peroxiredoxins 7 , its precise mechanism of toxicity and the existence of dedicated bacterial defence systems remain unknown. Here, we identify HiuH as a periplasmic enzyme, conserved across E. coli strains, that specifically degrades UH. Our findings reveal that UH selectively induces the expression of hiuH and that HiuH efficiently detoxifies UH both in vitro and in bacterial cells. HiuH cooperates with MsrP, a periplasmic methionine sulfoxide reductase that repairs UH-induced protein-bound methionine oxidation. This combined defence offering both direct detoxification and damage repair, is essential for bacterial survival under UH stress, and confers a competitive fitness advantage in a DSS-induced mouse model of colitis. Although UH is chemically transient, our work shows that it imposes durable biological consequences and a sufficient fitness cost in the in vivo niches occupied by E. coli to favour the evolution of a dedicated detoxification pathway beyond general oxidative-stress responses, defining a key adaptation to periods of gut inflammation.
Natural biopolymer-based Pickering emulsions have emerged as promising green delivery systems for lipophilic bioactives. Agar exhibits excessive hydrophilicity with poor amphiphilic balance. Chitosan has limited solubility at physiological pH and weak independent gelation capacity. Simvastatin is a widely used lipid-lowering drug with an oral bioavailability of only about 5% due to poor aqueous solubility and gastrointestinal instability. To address these critical gaps, agar-chitosan composite particles (AGCS) were fabricated via spray-drying to stabilize Pickering emulsions for simvastatin delivery. FT-IR confirmed that electrostatic and hydrogen bonding modulated composite particle amphiphilicity. This resulted in a 97.27° contact angle and reduced interfacial tension of 13.5 mN/m. The emulsions exhibited exceptional stability at pH greater than 5 and salt levels less than 150 mmol/L. They also retained structural integrity after heat treatment up to 100 °C. This stability arose from a dual mechanism involving a dense interfacial film and a self-assembled three-dimensional gel network. Rheological analysis revealed elastic-dominated behavior supporting a 95% encapsulation efficiency at 60% oil phase fraction. In vitro digestion demonstrated that composite emulsion gels protected simvastatin from gastric degradation while enhancing bioaccessibility to 33.5% compared to free simvastatin. This work elucidates the synergistic stabilization mechanism of agar-chitosan composite particles. These particles overcome the individual limitations of native polysaccharides. The findings highlight their potential as a green biocompatible carrier for lipophilic drug delivery in biomedicine and the food industry.