Structural and rheological characterization of water-soluble and alkaline-soluble fibers from hulless barley.

BACKGROUND: Highland hulless barley has garnered attention as a promising economic product and a potential healthy food ingredient. The present study aimed to comprehensively investigate the molecular structure of extractable fibers obtained from a specific highland hulless barley. Water-soluble fiber (WSF) and alkaline-soluble fiber (ASF) were extracted using enzymatic digestion and an alkaline method, respectively. The purified fibers underwent a thorough investigation for their structural characterization. RESULTS: The monosaccharide composition revealed that WSF primarily consisted of glucose (91.7%), whereas ASF was composed of arabinose (54.5%) and xylose (45.5%), indicating the presence of an arabinoxylan molecule with an A/X ratio of 1.2. The refined structural information was further confirmed through methylation, 1 H NMR and Fourier-transform infrared spectroscopy analyses. WSF fiber exclusively exhibited α-anomeric patterns, suggesting it was an α-glucan. It has a low molecular weight of 5 kDa, as determined by gel permeation chromatography. Conversely, ASF was identified as a heavily branched arabinoxylan with 41.55% of '→2,3,4)-Xylp-(1→' linkages. ASF and WSF exhibited notable differences in their morphology, water absorption capabilities and rheological properties. CONCLUSION: Based on these findings, molecular models of WSF and ASF were proposed. The deep characterization of these fiber structures provides valuable insights into their physicochemical and functional properties, thereby unlocking their potential applications in the food industry. © 2023 Society of Chemical Industry.

Metal-Polyphenol-Network Coated Prussian Blue Nanoparticles for Synergistic Ferroptosis and Apoptosis via Triggered GPX4 Inhibition and Concurrent In Situ Bleomycin Toxification.

Given that traditional anticancer therapies fail to significantly improve the prognoses of triple negative breast cancer (TNBC), new modalities with high efficiency are urgently needed. Herein, by mixing the metal-phenolic network formed by tannic acid (TA), bleomycin (BLM), and Fe3+ with glutathione peroxidase 4 (GPX4) inhibitor (ML210) loaded hollow mesoporous Prussian blue (HMPB) nanocubes, the HMPB/ML210@TA-BLM-Fe3+ (HMTBF) nanocomplex is prepared to favor the ferroptosis/apoptosis synergism in TNBC. During the intracellular degradation, Fe3+ /Fe2+ conversion mediated by TA can initiate the Fenton reaction to drastically upregulate the reactive oxygen species level in cells, subsequently induce the accumulation of lipid peroxidation, and thereby cause ferroptotic cell death; meanwhile, the released ML210 efficiently represses the activity of GPX4 to activate ferroptosis pathway. Besides, the chelation of Fe2+ with BLM leads to in situ BLM toxification at tumor site, then triggers an effective apoptosis to synergize with ferroptosis for tumor therapy. As a result, the superior in vivo antitumor efficacy of HMTBF is corroborated in a 4T1 tumor-bearing mice model regarding tumor growth suppression, indicating that the nanoformulations can serve as efficient ferroptosis and apoptosis inducers for use in combinatorial TNBC therapy.

An artificial intelligence process of immunoassay for multiple biomarkers based on logic gates.

We present a universal platform to synchronously analyze the possible existing state of two protein biomarkers. This platform is based on the integration of three logic gates: NAND, OR and NOT. These logic gates were constructed by the principle of immune recognition and fluorescence quenching between fluorescein labelled antibodies/antigens and antibody-conjugated graphene oxide (GO). An artificial intelligence (AI) protein analysis process was designed by us and accordingly a small program was written in JAVA. This protein analysis process with its JAVA code may be applied to give logic judgments on the possible existing state of two protein components. We expect that our fundamental research on multiple biomarker analysis can provide potential application in AI-assisted medical diagnosis with the interface for remote medical treatment.

A self-amplified nanocatalytic system for achieving "1 + 1 + 1 > 3" chemodynamic therapy on triple negative breast cancer.

BACKGROUND: Chemodynamic therapy (CDT), employing Fenton or Fenton-like catalysts to convert hydrogen peroxide (H2O2) into toxic hydroxyl radicals (·OH) to kill cancer cells, holds great promise in tumor therapy due to its high selectivity. However, the therapeutic effect is significantly limited by insufficient intracellular H2O2 level in tumor cells. Fortunately, ß-Lapachone (Lapa) that can exert H2O2-supplementing functionality under the catalysis of nicotinamide adenine dinucleotide (phosphate) NAD(P)H: quinone oxidoreductase-1 (NQO1) enzyme offers a new idea to solve this problem. However, extensive DNA damage caused by high levels of reactive oxygen species can trigger the "hyperactivation" of poly(ADP-ribose) polymerase (PARP), which results in the severe interruption of H2O2 supply and further the reduced efficacy of CDT. Herein, we report a self-amplified nanocatalytic system (ZIF67/Ola/Lapa) to co-deliver the PARP inhibitor Olaparib (Ola) and NQO1-bioactivatable drug Lapa for sustainable H2O2 production and augmented CDT ("1 + 1 + 1 > 3"). RESULTS: The effective inhibition of PARP by Ola can synergize Lapa to enhance H2O2 formation due to the continuous NQO1 redox cycling. In turn, the high levels of H2O2 further react with Co2+ to produce the highly toxic ·OH by Fenton-like reaction, dramatically improving CDT. Both in vitro and in vivo studies demonstrate the excellent antitumor activity of ZIF67/Ola/Lapa in NQO1 overexpressed MDA-MB-231 tumor cells. Importantly, the nanocomposite presents minimal systemic toxicity in normal tissues due to the low NQO1 expression. CONCLUSIONS: This design of nanocatalytic system offers a new paradigm for combing PARP inhibitor, NQO1-bioactivatable drug and Fenton-reagents to obtain sustained H2O2 generation for tumor-specific self-amplified CDT.

A RuII Polypyridyl Alkyne Complex Based Metal-Organic Frameworks for Combined Photodynamic/Photothermal/Chemotherapy.

Despite drug delivery nanoplatforms receiving extensive attention, development of a simple, effective, and multifunctional theranostics nanoplatform still remains a challenge. Herein, a versatile nanoplatform based on a zirconium framework (UiO-66-N3 ) was synthesized, which demonstrated a combined photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy (CT) for cancer treatment. A RuII polypyridyl alkyne complex (Ra) as a photosensitizer was modified into a nanoplatform by click reactions for the first time. When exposed to suitable light irradiation, the as-prepared multifunctional nanoplatform (UiO-Ra-DOX-CuS) not only demonstrated efficient 1 O2 generation, but also exhibited excellent photothermal conversion ability. In particular, the nanotherapeutic agent presented a dual-stimuli response; either acidic environment or NIR laser irradiation would trigger the drug release. The synergetic efficacy of UiO-Ra-DOX-CuS combined PDT, PTT, and CT, which was evaluated by cell experiments. Moreover, the design could promote the development of RuII polypyridyl alkyne complexes based multifunctional nanoparticles and multimodal cancer treatment.

Effect of the Ancillary Ligands on the Spectral Properties and G-Quadruplexes DNA Binding Behavior: A Combined Experimental and Theoretical Study.

In an effort to explore the effect of ancillary ligands on the spectral properties and overall G-quadruplex DNA binding behavior, two new ruthenium(II) complexes [Ru(phen)2 (dppzi)](2+) (1) and [Ru(dmp)2 (dppzi)](2+) (2) (phen=1,10-phenanthroline, dmp=2,9-dimethyl-1,10-phenanthroline, dppzi=dipyrido[3,2-a:2',3'-c]phenazine-10,11-imidazole) were prepared. Complex 1 can emit luminescence in the absence and presence of G-quadruplexes DNA. However, with -CH3 substituent on the 2- and 9-positions of the phen ancillary ligand, no detectable luminescence is observed for complex 2 in any organic solvent or in the absence and/or presence of G-quadruplex DNA. Experimental and molecular docking studies indicated that both complexes interacted with the human telomeric repeat AG3(T2AG3)3 (22AG) G-quadruplex with the stoichiometric ratio of 1:1, but the two complexes showed different G-quadruplex DNA binding affinity. Complex 1 binds to the G-quadruplexes DNA more tightly than complex 2 does. Our results demonstrate that methyl groups on the phen ancillary ligand significantly affect the spectral properties and the overall DNA binding behavior of the complexes. Such difference in spectral properties and DNA binding affinities of these two complexes can be reasonably explained by DFT/TD-DFT calculations. This work provides guidance not only on exploring the G-quadruplexes DNA binding behavior of complexes, but also understanding the unique luminescence mechanism.

Binding Behaviors for Different Types of DNA G-Quadruplexes: Enantiomers of [Ru(bpy)2(L)](2+) (L=dppz, dppz-idzo).

Polymorphic DNA G-quadruplex recognition has attracted great interest in recent years. The strong binding affinity and potential enantioselectivity of chiral [Ru(bpy)2 (L)](2+) (L=dipyrido[3,2-a:2',3'-c]phenazine, dppz-10,11-imidazolone; bpy=2,2'-bipyridine) prompted this investigation as to whether the two enantiomers, Δ and Λ, can show different effects on diverse structures with a range of parallel, antiparallel and mixed parallel/antiparallel G-quadruplexes. These studies provide a striking example of chiral-selective recognition of DNA G-quadruplexes. As for antiparallel (tel-Na(+)) basket G-quadruplex, the Λ enantiomers bind stronger than the Δ enantiomers. Moreover, the behavior reported here for both enantiomers stands in sharp contrast to B-DNA binding. The chiral selectivity toward mixed parallel/antiparallel (tel-K(+)) G-quadruplex of both compounds is weak. Different loop arrangements can change chiral complex selectivity for both antiparallel and mixed parallel/antiparallel G-quadruplex. Whereas both Δ and Λ isomers bind to parallel G-quadruplexes with comparable affinity, no appreciable stereoselective G-quadruplex binding of the isomers was observed. In addition, different binding stoichiometries and binding modes for Δ and Λ enantiomers were confirmed. The results presented here indicate that chiral selective G-quadruplex binding is not only related to G-quadruplex topology, but also to the sequence and the loop constitution.

Molecular "light switch" [Ru(phen)2dppzidzo](2+) monitoring the aggregation of tau.

Monitoring the aggregation of the tau protein is a key protocol for elucidating the pathogenic mechanism of Alzheimer's disease. In the present article, [Ru(phen)2dppzidzo](2+), a "light switch" ruthenium(ii) complex, was presented as a new monitoring probe for the aggregation of a tau R3 peptide, the third repeat unit of the tau microtubule-binding domain. Having little impact on the aggregation process, large fixed Stokes shift and small background luminescence made the complex a better probe for monitoring the aggregation process and quantitatively detecting tau filaments compared to thioflavin S, a commonly used fluorescent dye for staining neurofibrillary tangles and monitoring tau aggregation. Furthermore, a long luminescence lifetime of this complex could also expand its potential usage in the detection of tau filaments in the presence of short-lived fluorescent backgrounds.

Label-free fluorescent DNA biosensors based on metallointercalators and nanomaterials.

DNA based biosensors have become increasingly important in medical diagnostics, genetic and drug screening, and forensics in this post-genomic era. Chemical labeling methods suffer from several drawbacks, which are tedious, cost-expensive and time-consuming, thus the development of simple and general label free strategies is being demanded. The present article introduces a new model of biosensor device based on both metallointercalators and nanomaterials, with the aim of highlighting, in particular, the use of the "label-free" strategy for the construction of simple and inexpensive sensing platforms. In this work, two strategies were developed for designing "label-free" sensors: (1) metallointercalators act as the quencher to nanomaterials; (2) nanomaterials act as the quencher to metallointercalators. These methods take advantage of the sensitive luminescence signal change of metallointercalators or nanomaterials upon analytes binding. By monitoring the luminescence change, we were able to detect metal ions and biomolecules. Compared to other label-free fluorescent methods, these "label-free" DNA biosensors provide fast, simple, economical, sensitive and selective detection of target analytes with specific probes.

Enrichment and characterization of human-associated mucin-degrading microbial consortia by sequential passage.

Mucin is a glycoprotein secreted throughout the mammalian gastrointestinal tract that can support endogenous microorganisms in the absence of complex polysaccharides. While several mucin-degrading bacteria have been identified, the interindividual differences in microbial communities capable of metabolizing this complex polymer are not well described. To determine whether community assembly on mucin is deterministic across individuals or whether taxonomically distinct but functionally similar mucin-degrading communities are selected across fecal inocula, we used a 10-day in vitro sequential batch culture fermentation from three human donors with mucin as the sole carbon source. For each donor, 16S rRNA gene amplicon sequencing was used to characterize microbial community succession, and the short-chain fatty acid profile was determined from the final community. All three communities reached a steady-state by day 7 in which the community composition stabilized. Taxonomic comparisons amongst communities revealed that one of the final communities had Desulfovibrio, another had Akkermansia, and all three shared other members, such as Bacteroides. Metabolic output differences were most notable for one of the donor's communities, with significantly less production of acetate and propionate than the other two communities. These findings demonstrate the feasibility of developing stable mucin-degrading communities with shared and unique taxa. Furthermore, the mechanisms and efficiencies of mucin degradation across individuals are important for understanding how this community-level process impacts human health.

Molecular Deformation Is a Key Factor in Screening Aggregation Inhibitor for Intrinsically Disordered Protein Tau.

Direct inhibitor of tau aggregation has been extensively studied as potential therapeutic agents for Alzheimer's disease. However, the natively unfolded structure of tau complicates the structure-based ligand design, and the relatively large surface areas that mediate tau-tau interactions in aggregation limit the potential for identifying high-affinity ligand binding sites. Herein, a group of isatin-pyrrolidinylpyridine derivative isomers (IPP1-IPP4) were designed and synthesized. They are like different forms of molecular "transformers". These isatin isomers exhibit different inhibitory effects on tau self-aggregation or even possess a depolymerizing effect. Our results revealed for the first time that the direct inhibitor of tau protein aggregation is not only determined by the previously reported conjugated structure, substituent, hydrogen bond donor, etc. but also depends more importantly on the molecular shape. In combination with molecular docking and molecular dynamics simulations, a new inhibition mechanism was proposed: like a "molecular clip", IPP1 could noncovalently bind and fix a tau polypeptide chain at a multipoint to prevent the transition from the "natively unfolded conformation" to the "aggregation competent conformation" before nucleation. At the cellular and animal levels, the effectiveness of the inhibitor of the IPP1 has been confirmed, providing an innovative design strategy as well as a lead compound for Alzheimer's disease drug development.

Protein combined with certain dietary fibers increases butyrate production in gut microbiota fermentation.

The modern diet delivers nearly equal amounts of carbohydrates and protein into the colon representing an important protein increase compared to past higher fiber diets. At the same time, plant-based protein foods have become increasingly popular, and these sources of protein are generally less digestible than animal protein sources. As a result, a significant amount of protein is expected to reach the colon and be available for fermentation by gut microbiota. While studies on diet-microbiota interventions have mainly focused on carbohydrate fermentation, limited attention has been given to the role of protein or protein-fiber mixtures as fermentation substrates for the colonic microbiota. In this study, we aimed to investigate: (1) how changing the ratio of protein to fiber substrates affects the types and quantities of gut microbial metabolites and bacteria; and (2) how the specific fermentation characteristics of different types of fiber might influence the utilization of protein by gut microbes to produce beneficial short chain fatty acids. Our results revealed that protein fermentation in the gut plays a crucial role in shaping the overall composition of microbiota communities and their metabolic outputs. Surprisingly, butyrate production was maintained or increased when fiber and protein were combined, and even when pure protein samples were used as substrates. These findings suggest that indigestible protein in fiber-rich substrates may promote the production of microbial butyrate perhaps including the later stages of fermentation in the large intestine.

Microbiota from human infants consuming secretors or non-secretors mothers' milk impacts the gut and immune system in mice.

Maternal secretor status is one of the determinants of human milk oligosaccharides (HMOs) composition, which, in turn, influences the gut microbiota composition of infants. To understand if this change in gut microbiota impacts immune cell composition, intestinal morphology, and gene expression, 21-day-old germ-free C57BL/6 mice were transplanted with fecal microbiota from infants whose mothers were either secretors (SMM) or non-secretors (NSM) or from infants consuming dairy-based formula (MFM). For each group, one set of mice was supplemented with HMOs. HMO supplementation did not significantly impact the microbiota diversity; however, SMM mice had a higher abundance of genus Bacteroides, Bifidobacterium, and Blautia, whereas, in the NSM group, there was a higher abundance of Akkermansia, Enterocloster, and Klebsiella. In MFM, gut microbiota was represented mainly by Parabacteroides, Ruminococcaceae_unclassified, and Clostrodium_sensu_stricto. In mesenteric lymph node, Foxp3+ T cells and innate lymphoid cells type 2 were increased in MFM mice supplemented with HMOs, while in the spleen, they were increased in SMM + HMOs mice. Similarly, serum immunoglobulin A was also elevated in MFM + HMOs group. Distinct global gene expression of the gut was observed in each microbiota group, which was enhanced with HMOs supplementation. Overall, our data show that distinct infant gut microbiota due to maternal secretor status or consumption of dairy-based formula and HMO supplementation impacts immune cell composition, antibody response, and intestinal gene expression in a mouse model. IMPORTANCE: Early life factors like neonatal diet modulate gut microbiota, which is important for the optimal gut and immune function. One such factor, human milk oligosaccharides (HMOs), the composition of which is determined by maternal secretor status, has a profound effect on infant gut microbiota. However, how the infant gut microbiota composition determined by maternal secretor status or consumption of infant formula devoid of HMOs impacts infant intestinal ammorphology, gene expression, and immune signature is not well explored. This study provides insights into the differential establishment of infant microbiota derived from infants fed by secretor or non-secretor mothers milk or those consuming infant formula and demonstrates that the secretor status of mothers promotes Bifidobacteria and Bacteroides sps. establishment. This study also shows that supplementation of pooled HMOs in mice changed immune cell composition in the spleen and mesenteric lymph nodes and immunoglobulins in circulation. Hence, this study highlights that maternal secretor status has a role in infant gut microbiota composition, and this, in turn, can impact host gut and immune system.

Molecular hairpin: a possible model for inhibition of tau aggregation by tannic acid.

Inhibition of anomalous aggregation of tau protein would be an attractive therapeutic target for Alzheimer's disease (AD). In this study, tannic acid (TA), a polymeric plant polyphenol, and its monomer, gallic acid (GA), were introduced as the references to afford a molecular framework that integrates tau binding properties and inhibitory effects. Using a thioflavin S fluorescence assay and electron microscopy, we demonstrated that TA could competently inhibit the in vitro aggregation of tau peptide R3, corresponding to the third repeat unit of the microtubule-binding domain, with an IC50 of 3.5 µM, while GA's inhibition was comparatively piddling (with an IC50 of 92 µM). In the isothermal titration calorimetry experiment, we found that TA could strongly bind to R3 with a large amount of heat released. Circular dichroism spectra showed TA dose-dependently suppressed the conformational transition of R3 from a random coil structure to a ß-sheet structure during the aggregation process. Finally, a structural model was built using molecular docking simulation to elucidate the possible binding sites for TA on the tau peptide surface. Our results suggest that TA recognizably interacts with tau peptide by forming a hairpin binding motif, a key framework required for inhibiting tau polymerization, in addition to hydrogen bonding, hydrophilic-hydrophobic interactions, and static electrical interactions, as reported previously. The inhibitory effect of TA on human full-length tau protein (tau441) was also verified by electron microscopy. This finding hints at the possibility of TA as a leading compound of anti-AD drugs and offers a new stratagem for the rational molecular design of a tau aggregation inhibitor.

Label-free fluorescent DNA sensor for the detection of silver ions based on molecular light switch Ru complex and unmodified quantum dots.

Using molecular light switch Ru complex Ru(bpy)(2)(dppz)(2+) and CdTe quantum dots (QDs), we have designed a label-free DNA fluorescent sensor for the detection of Ag(+) in aqueous solution.

A new fluorescence "switch on" assay for heparin detection by using a functional ruthenium polypyridyl complex.

In the present study, a new strategy for heparin detection and quantification in biological media, such as fetal bovine serum (FBS), is developed by monitoring the emission change of a functional ruthenium polypyridyl complex ([Ru(phen)(2)dppz-idzo](2+), complex 1) in buffer solution. Polyanionic heparin is found to interact with a positively charged Ru-complex through electrostatic effects and/or hydrogen bonding interactions, which leads to a significant fluorescence enhancement of the Ru-complex. To get insight into this fluorescence "switch on" behavior, the binding model of the Ru-complex to heparin is established by employing molecular docking simulations based on the fluorescence and UV absorption results. The selectivity results of the fluorescence assay reveal that our complex displayed good fluorescence selectivity towards heparin over its analogues, such as chondroitin 4-sulfate (Chs) or hyaluronic acid (Hya), which have lower charge density and/or structural compatibility as compared to that of heparin. Quantification of heparin is also performed and a linear calibration curve is observed in the range of 0.01-4.87 U mL(-1) (the limit of detection is 0.01 U mL(-1)) for heparin detection in diluted FBS solution. This "one-step" fluorescence "switch on" assay for heparin detection is label-free, convenient, sensitive and selective, and has a long emission wavelength and large Stokes shift.

Investigation on the aggregation behaviors and filament morphology of tau protein by a simple 90° angle light-scattering assay.

The in vitro aggregation of tau constructs was monitored by a simple 90° angle light-scattering (LS) approach which was conducted directly on fluorescence instrument. At the optimum incident wavelength (550 nm, unpolarized), the sensitivity of LS was high enough to detect tau aggregation at micromolar range. The nucleation and elongation, different events in the aggregation process of 4RMBD construct (corresponding with the four repeated units of tau Microtubule Binding Domain) could be observed by this approach, as compared with ThS fluorescence assay. The validity of this technique was demonstrated over a range of tau concentrations with different tau filaments. Linear regression of scattering light against concentration yielded the x-intercept, the critical concentrations of tau constructs. The critical concentrations of 4RMBD and its S305N mutant are 5.26 µM and 4.04 µM respectively, indicating point mutation S305N, which is associated with FTDP-17, appear to enhance the heparin-induced tau aggregation in vitro. Furthermore, the slopes of concentration dependence curves, as well as the angle dependence, were discussed based on the filaments morphology examined by electron microscopy and ultrasonication experiment.

Complexing curcumin and resveratrol in the starch crystalline network alters in vitro starch digestion: Towards developing healthy food materials.

Starch is an abundant and common food ingredient capable of complexing with various bioactive compounds (BCs), including polyphenols. However, little information is available about using native starch network arrangement for the starch-BCs inclusion. Herein, two BCs, curcumin, and resveratrol, were undertaken to delineate the role of different starch crystalline types on their encapsulation efficiency. Four starches with different crystalline types, botanical sources, and amylose content were examined. The results suggest that B-type hexagonal packing is necessary to encapsulate curcumin and resveratrol successfully. The increase in XRD crystallinity while maintaining the FTIR band at 1048/1016 cm-1 suggests that BCs are likely entrapped inside the starch granule than attaching to the granule surface. A significant change in starch digestion is seen only for the B-starch complexes. Embedding BCs in the starch network and controlling starch digestion could be a cost-effective and valuable approach to designing and developing novel starch-based functional food ingredients.

Structure and Function of Polysaccharides and Oligosaccharides in Foods.

Polysaccharides and oligosaccharides are abundantly found in various foods [...].

Impact of Six Extraction Methods on Molecular Composition and Antioxidant Activity of Polysaccharides from Young Hulless Barley Leaves.

Young hulless barley leaves are gaining recognition for potential health benefits, and the method of extracting polysaccharides from them is critical for potential food industry applications. This study delves into a comparative analysis of six distinct fiber extraction techniques: hot water extraction; high-pressure steam extraction; alkaline extraction; xylanase extraction; cellulase extraction; and combined xylanase and cellulase extraction. This analysis included a thorough comparison of polysaccharide-monosaccharide composition, structural properties, antioxidant activities (DPPH, ABTS, and FRAP), and rheological properties among fibers extracted using these methods. The results underscore that the combined enzymatic extraction method yielded the highest extraction yield (22.63%), while the rest of the methods yielded reasonable yields (~20%), except for hot water extraction (4.11%). Monosaccharide composition exhibited divergence across methods; alkaline extraction yielded a high abundance of xylose residues, whereas the three enzymatic methods demonstrated elevated galactose components. The extracted crude polysaccharides exhibited relatively low molecular weights, ranging from 5.919 × 104 Da to 3.773 × 105 Da across different extraction methods. Regarding antioxidant activities, alkaline extraction yielded the highest value in the ABTS assay, whereas enzymatically extracted polysaccharides, despite higher yield, demonstrated lower antioxidant capacity. In addition, enzymatically extracted polysaccharides exerted stronger shear thinning behavior and higher initial viscosity.