Structural Characterization Research Articles

Structural characterization and prebiotic potential of polysaccharides from Polygonatum sibiricum

Polygonatum sibiricum has been widely used due to its excellent biological activities. We prepared a novel polysaccharide from P. sibiricum (PSP) in this study. According a monosaccharide composition analysis, PSP was mainly composed of fructose and glucose with a molar percentage of 93.81:5.12. The main linkage types were identified as α-D-Glcp-1→ and →2-β-D-Fruf-1→. The molecular weight of PSP showed no significant change after simulated salivary and gastrointestinal digestion. However, PSP could be broken down by intestinal bacteria. Our findings revealed that PSP administration increased the abundance of probiotics such as Bifidobacterium. Furthermore, the results showed that gut microbes could utilize PSP to produce short-chain fatty acids including acetic acid, propionic acid, and butyric acid. Also, the PSP fermentation broth displayed an excellent scavenging effect on free radicals, including 2,2-diphenyl-1-picrylhydrazyl radical, superoxide radical, and hydroxyl radical. In summary, this study will help to promote the application of PSP as prebiotics in functional food and the medical industry.

Combating Aminoglycoside Resistance: From Structural and Functional Characterisation to Therapeutic Challenges with RKAAT.

A comprehensive knowledge of aminoglycoside-modifying enzymes (AMEs) and their role in bacterial resistance mechanisms is urgently required due to the rising incidence of antibiotic resistance, particularly in Klebsiella pneumoniae infections. This study explores the essential features of AMEs, including their structural and functional properties, the processes by which they contribute to antibiotic resistance, and the therapeutic importance of aminoglycosides. The study primarily examines the Recombinant Klebsiella pneumoniae Aminoglycoside Adenylyl Transferase (RKAAT), particularly emphasizing its biophysical characteristics and the sorts of resistance it imparts. Furthermore, this study examines the challenges presented by RKAAT-mediated resistance, an evaluation of treatment methods and constraints, and options for controlling infection. The analysis provides a prospective outlook on strategies to address and reduce antibiotic resistance. This extensive investigation seeks to provide vital insights into the continuing fight against bacterial resistance, directing future research efforts and medicinal approaches.

Structural characterization of three acidic polysaccharides from Opuntia dillenii Haw. fruits and their protective effect against hydrogen peroxide-induced oxidative stress in Huh-7 cells

Three novel acidic polysaccharide fractions (OFPP-1, OFPP-2, OFPP-3) with different molecular weights (803.7, 555.1 and 414.5 kDa) were isolated from the peeled Opuntia dillenii Haw. fruits by alkali-extraction, graded alcohol precipitation and column chromatography. Structural analysis indicated that OFPPs were pectic polysaccharides consisting of rhamnose, arabinose and galactose residues. The backbone of OFPP-1 consisted of a repeating unit →6-α-D-GalpA-(1→2)-α-L-Rhap-(1→ with T-α-D-GalpA-(1→6)-α-D-GalpA-(1→4)-α-D-Glcp-(1→, T-β-D-Xylp-(1→6)-α-D-GalpA-(1→4)-α-D-Glcp-(1→ or T-α-D-GalpA-(1→3)-α-L-Araf-(1→ as the side chains. The backbone of OFPP-2 consisted of a disaccharide repeating unit →2)-α-L-Rhap-(1→4)-β-D-GalpA-(1→ with T-β-L-Araf-(1→ as the branches substituted at the O-4 position of →2,4)-α-L-Rhap-(1→. Whereas the backbone of OFPP-3 was →2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-β-L-Araf-(1→ or →2,4)-α-L-Rhap-(1→2)-α-L-Rhap-(1→4)-β-D-GalpA-(1→, which was branched at the O-4 position of →2,4)-α-L-Rhap-(1→. Moreover, these 3 polysaccharide fractions could protect Huh-7 cells against H2O2-induced oxidative stress to different extents by decreasing the MDA content and increasing the SOD, CAT, GSH-Px activities and the GSH level in the Huh-7 cells. These results suggest that OFPPs have the potential to be used as natural antioxidants.

Tailoring Auger Recombination Dynamics in CsPbI3 Perovskite Nanocrystals via Transition Metal Doping.

Auger recombination is a pivotal process for semiconductor nanocrystals (NCs), significantly affecting charge carrier generation and collection in optoelectronic devices. This process depends mainly on the NCs' electronic structures. In our study, we investigated Auger recombination dynamics in manganese (Mn2+)-doped CsPbI3 NCs using transient absorption (TA) spectroscopy combined with theoretical and experimental structural characterization. Our results show that Mn2+ doping accelerates Auger recombination, reducing the biexciton lifetime from 146 to 74 ps with increasing Mn doping concentration up to 10%. This accelerated Auger recombination in Mn-doped NCs is attributed to increased band edge wave function overlap of excitons and a larger density of final states of Auger recombination due to Mn orbital involvement. Moreover, Mn doping reduces the dielectric screening of the excitons, which also contributes to the accelerated Auger recombination. Our study demonstrates the potential of element doping to regulate Auger recombination rates by modifying the materials' electronic structure.

Improved Urea Oxidation Performance via Interface Electron Redistributions of the NiFe(OH)x/MnO2/NF p-p Heterojunction.

The development of highly efficient urea oxidation reaction (UOR) electrocatalysts is the key to simultaneously achieving green hydrogen production and the treatment of urea-containing wastewater. Ni-based electrocatalysts are expected to replace precious metal catalysts for UOR because of their high activity and low cost. However, the construction of Ni-based electrocatalysts that can synergistically enhance UOR still needs further in-depth study. In this study, highly active electrocatalysts of NiFe(OH)x/MnO2 p-p heterostructures are constructed on nickelfoam (NF) by electrodeposition (NiFe(OH)x/MnO2/NF), illustrating the effect of electronic structure changes at heterogeneous interfaces on UOR and revealing the catalytic mechanism of UOR. The NiFe(OH)x/MnO2/NF only needs 1.364V (vs Reversible Hydrogen Electrode, RHE) to reach 10mA cm-2 for UOR. Structural characterizations and theoretical calculations indicate that energy gap leads to directed charge transfer and redistribution at the heterojunction interface, forming electron-rich (MnO2) and electron-poor (NiFe(OH)x) regions. This enhances the catalyst's adsorption of urea and reaction intermediates, reduces thermodynamic barriers during the UOR process, promotes the formation of Ni3+ phases at lower potentials, and thus improves UOR performance. This work provides a new idea for the development of Ni-based high-efficiency UOR electrocatalysts.

On Tautomerism and Amphoterism: An In-Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts.

Ammeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single-crystal X-ray diffraction. In this structure, ammeline is exclusively found as its 4,6‑diamino-1,3,5-triazin-2(1H)-one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products' thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high-energy-density materials.

On Tautomerism and Amphoterism: An In‐Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts

AbstractAmmeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single‐crystal X‐ray diffraction. In this structure, ammeline is exclusively found as its 4,6‐diamino‐1,3,5‐triazin‐2(1H)‐one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products’ thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high‐energy‐density materials.

Online Mixed-Bed Ion Exchange Chromatography for Native Top-Down Proteomics of Complex Mixtures.

Native top-down mass spectrometry (nTDMS) allows characterization of protein structure and noncovalent interactions with simultaneous sequence mapping and proteoform characterization. The majority of nTDMS studies utilize purified recombinant proteins, with significant challenges hindering application to endogenous systems. To perform native top-down proteomics (nTDP), where endogenous proteins from complex biological systems are analyzed by nTDMS, it is essential to separate proteins under nondenaturing conditions. However, it remains difficult to achieve high resolution with MS-compatible online chromatography while preserving protein tertiary structure and noncovalent interactions. Herein, we report the use of online mixed-bed ion exchange chromatography (IEC) to enable separation of endogenous proteins from complex mixtures under nondenaturing conditions, preserving noncovalent interactions for nTDP analysis. We have successfully detected large proteins (>146 kDa) and identified endogenous metal-binding and oligomeric protein complexes in human heart tissue lysate. The use of a mixed-bed stationary phase allowed retention and elution of proteins over a wide range of isoelectric points without altering the sample or mobile phase pH. Overall, our method provides a simple online IEC-MS platform that can effectively separate proteins from complex mixtures under nondenaturing conditions and preserve higher-order structure for nTDP applications.

Structural Characterization of Enzymatic Interactions with Functional Nicotinamide Cofactor Biomimetics

Synthetic nicotinamide biomimetics (NCBs) have emerged as alternatives to the use of natural cofactors. The relatively low cost and ease of manufacture of NCBs may enable the scaling of biocatalytic reactions to produce bulk chemicals (e.g., biofuels and plastics). NCBs are also recognized by only a subset of NAD(P)/NAD(P)H-dependent enzymes, which potentially allows access to orthogonal redox cascades that can be run simultaneously within a single reactor. In the work presented here, a series of NCBs was prepared and tested for activity with alcohol dehydrogenases and ene-reductases. While the NCBs did not support enzymatic activity with the alcohol dehydrogenases, the observed rate of the ene-reductases with NCBs was greater than when incubated with the natural cofactor (consistent with previous observations). We obtained the structures of an ene-reductase and an alcohol dehydrogenase with an NCB bound in their active sites. While the NCB bound to the ene-reductases in a productive position and orientation for hydride transfer to the isoalloxazine ring of the flavin cofactor, the NCB failed to adopt a catalytically competent binding mode in the alcohol dehydrogenase.

Gas separation in bimetallic Zn/Co-ZIF-62 glass membrane

Metal-organic framework (MOF) glasses, are attracting increasing attention in the gas separation field due to their component flexibility, ease of processing and porous structures. In this work, a series of bimetallic MOF glass membranes were synthesized and the impact of the metal node ratio (Co/Zn) on the gas separation performance of the membranes was investigated. It is found that the replacement of Zn nodes by Co in the ZIF-62 glass membrane leads to a nonlinear increase in the separation selectivity for CO2/CH4 and H2/CH4. Such a phenomenon corresponds to the mixed-metal node effect found in the MOF glass. Through the structural characterization results, we found that the different affinities of the central metal nodes towards gas molecules and the diversity in porosity of the Zn/Co-ZIF-62 membranes could be the two main reasons for the evolution of the gas separation properties in the ZIF-62 glass membranes. This work gives a new approach to developing MOF glass membranes with high-performance gas separation.

PH-Dependent interactions between β-casein and blueberry anthocyanins based on typical thermal processing conditions: Stability, structural characterization, and binding mechanisms

The color and structural stability of blueberry anthocyanins (BAs) are significantly affected by pH changes during processing. In this study, we present the potential effects of the thermal stability, structural characterization, and binding mechanism of BAs with β-casein (β-CN) at pH 2, 4, and 6 for the first time. The pH was found significantly affect the ability of β-CN to protect BAs from thermal, vitamin C, and sucrose induced degradation. Scanning electron microscopy (SEM) resolved the microstructural differences of β-CN-BAs at varying pH values. Multispectral analysis showed that as pH increases, the electrostatic interaction between β-CN and the major monomer of anthocyanins Cyanidin-3-O-glucoside (C3G) are replaced by hydrogen bonding and van der Waals forces, and then electrostatic interactions are again the dominant force. In vitro gastrointestinal digestion confirmed that the protein stabilized C3G under varying pH conditions. Nuclear magnetic resonance (NMR) spectroscopy reveals the connection between the multiple equilibrium forms of C3G (hemiketal, cis-chalcone, and trans-chalcone) and β-CN on the formation of complexes between multiple equilibrium forms to specifically elucidate the mechanism of its stabilizing effect. Molecular docking simulation revealed the significance of electrostatic interaction and hydrogen bonding, where the highest binding match was achieved at pH 2, with a minimum binding energy. These interactions can effectively promote stable complexation of β-CN with C3G. These findings have practical implications for protein regulation of the relationship between the equilibrium forms of different anthocyanins and can guide the stabilization of anthocyanin-rich products.

A hybrid pore-network-continuum modeling framework for flow and transport in 3D digital images of porous media

Understanding flow and transport in multiscale porous media is challenging due to the presence of a wide range of pore sizes. Recent imaging advances offer high-resolution characterization of the multiscale pore structures. However, simulating flow and transport in 3D digital images requires models to represent both the resolved and sub-resolution pore structures. We develop a hybrid pore-network-continuum modeling framework. The hybrid framework treats the smaller pores below the image resolution as a continuum using the Darcy-scale formalism and explicitly represents the larger pores resolved in the images employing a pore network model. We validate the hybrid model against direct numerical simulations for single-phase flow and solute transport and further demonstrate its applicability for simulating two-component gas transport in a shale rock sample. The results indicate that the new hybrid model represents the flow and transport process in multiscale porous media while being much more computationally efficient than direct numerical simulation methods for the range of simulated conditions.

Terpyridyl-Imidazole Based Ligand Coordinated to Ln(Hexafluoroacetyl acetonate)3 Core: Synthesis, Structural Characterization, Luminescence Properties, and Thermosensing Behaviors in Solution and PMMA Film.

A new array of ternary lanthanide complexes of the form [Ln(hfa)3(tpy-HImzphen)] have been synthesized and thoroughly characterized wherein Ln = LaIII (1), EuIII (2), SmIII (3), and TbIII (4); hfa = hexafluoroacetylacetonate; and tpy-HImzphen = 2-(4-[2,2':6',2″]terpyridin-4'-yl-phenyl)-1H-phenanthro[9,10-d]imidazole. Incorporation of tpy-HImzphen onto the Ln-hfa moiety induced a bathochromic shift of the absorption window of the complexes into the visible region. Extensive investigations of the luminescence characteristics have been conducted both at RT and at 77 K to understand the deactivation pathways of the complexes. Both steady-state and time-resolved emission spectral behaviors indicate four distinctive behaviors upon incorporation of tpy-HImzphen onto the lanthanide core, viz., a huge red-shift of the ligand-centered peak for LaIII; almost complete energy transfer for EuIII; very little energy transfer for SmIII, while reverse energy transfer in the case of TbIII. In addition, the EuIII-complex exhibits its excellence in luminescence thermometry in the solution state as well as in poly(methyl methacrylate) (PMMA) thin films. The thermosensitive luminescence response in solution was further utilized to mimic set-reset flip-flop logic operation. A plausible energy transfer scheme has been devised to explain dissimilar luminescence behaviors in the complexes. The role of LMCT was also considered for the observed thermosensing property of the Eu(III) complex.

Structural characterization of ligand binding and pH-specific enzymatic activity of mouse Acidic Mammalian Chitinase.

Chitin is an abundant biopolymer and pathogen-associated molecular pattern that stimulates a host innate immune response. Mammals express chitin-binding and chitin-degrading proteins to remove chitin from the body. One of these proteins, Acidic Mammalian Chitinase (AMCase), is an enzyme known for its ability to function under acidic conditions in the stomach but is also active in tissues with more neutral pHs, such as the lung. Here, we used a combination of biochemical, structural, and computational modeling approaches to examine how the mouse homolog (mAMCase) can act in both acidic and neutral environments. We measured kinetic properties of mAMCase activity across a broad pH range, quantifying its unusual dual activity optima at pH 2 and 7. We also solved high-resolution crystal structures of mAMCase in complex with oligomeric GlcNAcn, the building block of chitin, where we identified extensive conformational ligand heterogeneity. Leveraging these data, we conducted molecular dynamics simulations that suggest how a key catalytic residue could be protonated via distinct mechanisms in each of the two environmental pH ranges. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. Engineering proteins with tunable pH optima may provide new opportunities to develop improved enzyme variants, including AMCase, for therapeutic purposes in chitin degradation.

Understanding the Thermodynamics of Magnesium Binding to RNA Structural Motifs.

Divalent magnesium ions (Mg2+) serve a vital role in defining the structural and catalytic chemistry of a wide array of RNA molecules. The body of structural information on RNA motifs continues to expand and, in turn, the functional importance of Mg2+ is revealed. A combination of prior work on the structural characterization of magnesium binding ligands with inner- and outer-sphere coordination modes, with recorded experimental binding energies for inner- and outer-sphere contacts, demonstrates the relative affinity and thermodynamic hierarchy for these sites. In turn, these can be correlated with cellular concentrations of free available magnesium ions, allowing the prioritization of populating important functional sites and a correlation with physiological function. This paper summarizes some of the key results of that analysis and provides predictive rules for the affinity and role of newly identified Mg binding sites on complex RNA structures. The influence of crystal packing on magnesium binding to RNA motifs, relative to their solution form, is addressed and caveats made.

Fractal Characterization of the Pore-Throat Structure in Tight Sandstone Based on Low-Temperature Nitrogen Gas Adsorption and High-Pressure Mercury Injection

Fractal Characterization of the Pore-Throat Structure in Tight Sandstone Based on Low-Temperature Nitrogen Gas Adsorption and High-Pressure Mercury Injection

Focused reservoir characterization: analysis of selected sand units using well log and 3-D seismic data in 'Kukih' field, Onshore Niger Delta, Nigeria

This study focuses on the comprehensive reservoir characterization of the ‘Kukih’ Field within the onshore northeastern Niger Delta region, Nigeria. The absence of its detailed description with delineated reservoir properties, lateral continuity, and their use to identify potential reservoir quality and heterogeneity necessitated this study. Integrating well log and 3D seismic data, the investigation aims to elucidate reservoir properties, lithofacies, and depositional environments to unravel hydrocarbon potential. The geological setting, encompassing the Agbada Formation of Early and Middle Miocene age, is scrutinized through detailed geologic analysis. Petrophysical evaluation of four well logs (Kukih-1, Kukih-2, Kukih-3, and Kukih-4) facilitated the determination of key parameters such as shale volume, effective porosity, and water saturation. Seismic interpretation further enriched the structural characterization of the field. Results showcase three predominant reservoir sands (A, B, and C) with distinct lithofacies and thickness variations. Effective porosity ranges from Fair to Excellent, with permeability exhibiting high values for hydrocarbon reservoir potential. Water saturation trends, lithofacies distributions, and structural features were illuminated through iso-parametric maps and seismic analyses. Depositional environments were inferred through facies analysis, revealing the presence of funnel-, cylinder-, and bell-shaped successions that hint at intricate marine sedimentary processes. Challenges owing to limited core data were acknowledged, and the integration of methodologies emerged as a pivotal strategy for enhanced reservoir understanding. This study underscores the ‘Kukih’ Field's hydrocarbon potential, accentuating the significance of multidisciplinary approaches in deciphering complex reservoir systems. In light of the petrophysical analysis derived from the well logs and the identification of structural highs through the structural maps, this study recommends the drilling of unexplored zones exhibiting promising structural characteristics.

A rapid and successful method to synthesis of branched Poly(β-aminoester) as gene carrier system: Microwave-assisted polycondensation

Poly (β-amino ester)s (PBAEs) which are the efficient carriers for gene and drug delivery, synthesize by conventional polycondensation in a very long reaction time. The goal of this study is to shorten the reaction time without decreasing the efficacy of PBAE. For this purpose usability of microwave irradiation in the synthesis of the PBAE was investigated for the first time. The structural characterization of PBAE was realized using FTIR and 1H NMR, and its molecular weight was determined by the GPC-SEC. PBAE nanoparticles (nPBAEs) were also prepared and their physicochemical characteristics were determined. The transfection efficiency of nPBAE were determined on the Human Embryonic Kidney 293T (HEK293T) and Primary Ovine Fibroblast (POF) cells. All results were evaluated in comparison with those of the conventional product (PBAEc) as reference product. It was observed that both PBAE and PBAEc have same molecular structure and similar efficiency. This study revealed that PBAE was successfully synthesized by microwaves without decreasing its efficiency. When the synthesis of PBAE carried out by microwaves compared with conventional method, the reaction time and the consumed energy dramatically reduced from 48 h to 10 min and from 1.5 kWh to 0.032 kWh respectively.

Structural evolution in S-vacancy-rich Co@Co9S8 during selective benzyl alcohol electrooxidation reaction

Electrooxidation of organics using electrons as oxidants is a clean approach to produce commodity chemicals. However, designing an electrocatalyst with superior performance at low cell voltage remains a challenge. In this study, a series of VS-Co@Co9S8 electrocatalysts were fabricated by thermal reduction method using MOFs as templates. The catalytic oxidation performance and reaction mechanism of such specimens for benzyl alcohol were comprehensively analyzed by electrochemical measurement method and ex-situ structure characterization. The results show that Co@Co9S8-30 M has a unique three-dimensional (3D) micro cubic structure with abundant S vacancy (VS). These features accelerate the electrons and substrate transfer as well as provide plentiful active sites for benzyl alcohol electrooxidation reaction (BAOR). Consequently, the Co@Co9S8-30 M presented outstanding catalytic activity. The overpotential of 10 mA cm−2 (η10) was only 265.4 mV for BAOR. The conversion rate and benzoic acid selectivity were achieved to 72% and 90%, respectively. Particularly, the formation rate of benzoic acid was 7.247 mmol·gcat.−1·h−1. Moreover, the Co@Co9S8-30 M exhibited superior durability over 135 h. The coordination number of octahedral metal sites in Co9S8 did not match the number of Co 3 d orbital electrons, resulting in the weakening of bonding strength between Co and S elements. Thus, the Co@Co9S8 was reconstructed to Co3O4@CoOOH. Based on this assessment, the Co3O4@CoOOH was the active site of BAOR. This work provides theoretical guidance for the design of Co-based catalysts.

Structural and Property Characterizations of Dual-Responsive Core-Shell Tecto Dendrimers for Tumor Penetration and Gene Delivery Applications.

Core-shell tecto dendrimers (CSTDs) with excellent physicochemical properties and good tumor penetration and gene transfection efficiency have been demonstrated to have the potential to replace high-generation dendrimers in biomedical applications. However, their characterization and related biological properties of CSTDs for enhanced tumor penetration and gene delivery still lack in-depth investigation. Herein, we attempted to design three types of dual-responsive CSTDs for thorough physicochemical characterization and investigation of their tumor penetration and gene delivery efficiency. Three types of CSTDs were prepared through phenylborate ester bonds of phenylboronic acid (PBA)-decorated generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers as cores and monose (galactose, glucose or mannose)-conjugated G3 PAMAM dendrimers as shells and thoroughly characterized via NMR and other techniques. We show that the produced CSTDs displayed strong correlation signals between the PBA and monose protons and similar hydrodynamic diameters, and possess dual reactive oxygen species- and pH-responsivenesses. The dual-responsive CSTDs were proven to have structure-dependent tumor penetration property and gene delivery efficiency in terms of small interference RNA for gene silencing and plasmid DNA for gene editing, thus revealing a great potential for different biomedical applications. This article is protected by copyright. All rights reserved.