Refine
Has Fulltext
- no (140)
Year of publication
- 2018 (140) (remove)
Document Type
- Article (140) (remove)
Language
- English (140)
Is part of the Bibliography
- yes (140)
Keywords
- SERS (3)
- Through-space NMR shieldings (TSNMRS) (3)
- Conformational analysis (2)
- DBD dyes (2)
- DFT (2)
- DNA origami (2)
- Gas phase electron diffraction (2)
- Metabolomics (2)
- Molecular dynamics (2)
- biomarker (2)
- biomaterials (2)
- cancer (2)
- enzymes (2)
- heterocycles (2)
- isomerization (2)
- metathesis (2)
- nanoparticles (2)
- photochemistry (2)
- radiation therapy (2)
- ring-opening polymerization (2)
- ruthenium (2)
- self-assembly (2)
- stability (2)
- 1-(Dimethylamino)-1-phenyl-1-silacyclohexane (1)
- 3-Fluoro-3-methyl-3-silatetrahydropyran (1)
- 3D printing (1)
- 6-Mercaptopurine (1)
- AOT/BDAC micelles (1)
- APCI (1)
- ATCUN motif (1)
- Acetone process (1)
- Adsorption (1)
- Aerophobicity (1)
- Air bubble repellence (1)
- Alkenyl cyclohexanone (1)
- Alkenyl cyclohexenone (1)
- Alkynes (1)
- Anionic surfactant (1)
- Anisotropy (1)
- Anisotropy effect (1)
- Annelation effect (1)
- Anti-aromaticity (1)
- Anti-inflammatory (1)
- Antibody binding (1)
- Antimalarial drug detection (1)
- Antimicrobial (1)
- Arenes (1)
- Aromaticity (1)
- Artemisinin (1)
- Aryllithium compounds (1)
- Betaines (1)
- Biomaterial (1)
- Biophysical chemistry (1)
- Biopolymer (1)
- Birth Weight (1)
- Bombyx mori silk (1)
- Boric acid (1)
- Born-Oppenheimer MD (1)
- Boron exposure (1)
- C-reactive protein (1)
- Carbenes (1)
- Cartilage repair (1)
- Celastraceae (1)
- Cellular uptake (1)
- Chitosan (1)
- Chronic kidney disease (1)
- Click chemistry (1)
- Colloidal lithography (1)
- Conformation analysis (1)
- Contact angle (1)
- Correlation function (1)
- Cryo-SEM (1)
- Cyclotella (1)
- Cytotoxicity (1)
- DNA (1)
- DNA damage (1)
- DNA recognition (1)
- DNA strand breaks (1)
- DOHaD (1)
- DSC (1)
- Diatom (1)
- Dimer (1)
- Dispersion (1)
- Domino reactions (1)
- EPR spectroscopy (1)
- Ecological risk assessment (1)
- Ecotoxicology (1)
- Electro-synthesized molecularly imprinted polymer (1)
- Electrochemical sensor (1)
- Enzymes (1)
- Europium (1)
- Excimer (1)
- FRET (1)
- FSH (1)
- Fluorescence (1)
- Fluorescence correlation (1)
- Forster resonance energy transfer(FRET) (1)
- Functional organic materials (1)
- GIAO (1)
- Gestational diabetes (1)
- Gold nanotriangles (1)
- Gold surface (1)
- Gold surfaces (1)
- Guatemala (1)
- Heparin (1)
- Herbicide (1)
- Heterocycles (1)
- High School/Introductory Chemistry (1)
- Hydrogel (1)
- Hypertension (1)
- Hypoxia (1)
- In-line monitoring (1)
- Inflammation (1)
- Infrared spectroscopy (1)
- Iso-chemical-shielding surfaces (ICSS) (1)
- Janus emulsion (1)
- LH (1)
- LSPR (1)
- Lactose (1)
- Lake Peten-Itza (1)
- Lannea rivae (1)
- Lannea schweinfurthii (1)
- Large Stokes shifts (1)
- Laser-induced breakdown spectroscopy (LIBS) (1)
- Leguminosae (1)
- Leishmania (1)
- Light scattering (1)
- Low-temperature NMR (1)
- Low-temperature d-NMR (1)
- Luminescence (1)
- Lysophosphatidylcholine (1)
- M062X/6-311G** calculations (1)
- MACE (1)
- MAPbX3 (1)
- MP2 (1)
- MP2 and CCSD(T) calculations (1)
- MS (1)
- Magnetic-responsive (1)
- Mars (1)
- Matrix metalloproteinase (1)
- Maytenus boaria (1)
- Mesomerism (1)
- Metal-proton exchange reaction (1)
- Microwave chemistry (1)
- Molecular biophysics (1)
- Monte Carlo (1)
- Multifunctionality (1)
- Multivariate data analysis (1)
- NICS (1)
- NMR (1)
- NMR spectroscopy (1)
- NMR structure (1)
- Nanoparticles (1)
- Near infrared light triggered shape-recovery (1)
- Negative control (1)
- Nontarget terrestrial plants (1)
- On-demand release (1)
- Organic Chemistry (1)
- Oxygen heterocycles (1)
- PCM (1)
- PLA (1)
- Palladium-catalyzed cross-coupling of arenediazonium salts with organoindium or organobismuth reagents (1)
- Partial least squares regression (PLSR) (1)
- Perylene (1)
- Phosphatidylcholine acyl-alkyl C 32:1 (1)
- Photon Density Wave spectroscopy (1)
- Photon density wave spectroscopy (1)
- Pickering interfacial catalysis (1)
- Plant community model (1)
- Plant reproduction (1)
- Pleistocene (1)
- Poly(epsilon-caprolactone) networks (1)
- PolyNIPAM (1)
- Polymer functionalization (1)
- Polymer-coating (1)
- Polymerization (1)
- Porous poly(ether imide) microparticulate absorbers (1)
- Porous silicon (1)
- Principal component analysis (PCA) (1)
- Process analytical technology (1)
- Proline (1)
- Proteins (1)
- Pulsed interleaved excitation (1)
- RA-intramolecular hydrogen bond (1)
- Radical polymerization (1)
- Rare-earth elements (1)
- Rearrangement (1)
- Reproductive toxicity (1)
- Responsivity (1)
- Rheology (1)
- Ring current effect (1)
- STM-induced reactions (1)
- Scaffold contraction (1)
- Scaffold degradation (1)
- Scaffold stiffness (1)
- Semen parameters (1)
- Shape-memory polymer (1)
- Si(111)-7x7 (1)
- Single molecule fluorescence (1)
- Small angle neutron scattering (1)
- Sn(IV) alkoxide (1)
- Soil (1)
- Styrene (1)
- Superparamagnetic (1)
- Surface-initiated atom-transfer radical (1)
- Surfactant micelles (1)
- Switchable wettability (1)
- TCP (1)
- TEM (1)
- THP-1 cells (1)
- Temperature-memory effect (1)
- Template reaction (1)
- Tephrosia subtriflora (1)
- Testosterone (1)
- Thermo-responsive polymer (1)
- TiO2 nanotubes (1)
- Torque (1)
- Toxicity (1)
- Transient absorption (1)
- Turbid media (1)
- Type 2 Diabetes (1)
- UVB reduction (1)
- Uremic toxins (1)
- Vesicle (1)
- Vesicles (1)
- Vibronic spectrum (1)
- X-ray crystallography (1)
- X-ray diffraction (1)
- X-ray photoelectron spectroscopy (1)
- Zwitterionic surfactant (1)
- actin cytoskeleton (1)
- amphiphilic surface (1)
- anthracenes (1)
- anti-fouling materials (1)
- anti-inflammatory therapy (1)
- antifouling (1)
- antiplasmodial (1)
- aptamers (1)
- aridity (1)
- asymmetric catalysis (1)
- atomic force microscopy (1)
- azobenzene trimethylammonium bromide (1)
- biological applications of polymers (1)
- biphasic catalysis (1)
- block copolymers (1)
- bottom-up (1)
- calcium phosphate (1)
- calcium phosphate hybrid material (1)
- carbene ligands (1)
- carbohydrates (1)
- carotenoid (1)
- carotenoids (1)
- cascade reactions (1)
- catanionic surfactant bilayer (1)
- cation miscibility (1)
- cell adhesion (1)
- cell agglutination (1)
- cesium cation (1)
- charge transfer (1)
- chemical modification (1)
- chitosan (1)
- cluster models (1)
- cobalt nanoparticles (1)
- complexes (1)
- control body weight (1)
- copper (1)
- copper complex (1)
- core-shell materials (1)
- coumarins (1)
- crown compounds (1)
- crystal structure (1)
- crystallization (1)
- cyclic thermomechanical testing (1)
- cytotoxicity (1)
- dihydro-beta-agarofuran (1)
- dip-coating (1)
- dissociative electron attachment (1)
- disulfide (1)
- donor-acceptor systems (1)
- dyes/pigments (1)
- electromagnetic field enhancement (1)
- electrospray ionization mass spectrometry and modeling (1)
- endoperoxides (1)
- endothelial cells (1)
- energy-transfer (1)
- enzyme catalysis (1)
- enzyme-polymer conjugates (1)
- etanercept (1)
- fatty acids (1)
- ferromagnetic (1)
- fiber Bragg gratings (1)
- fiber etching (1)
- fiber-optical sensors (1)
- fibers (1)
- fibrinogen (1)
- fibroblast (1)
- flavonoid (1)
- flavonoids (1)
- flow photochemistry (1)
- fluorescence (1)
- fluorescent probes (1)
- focal adhesion (1)
- functionalization of polymers (1)
- galectin (1)
- gas chromatography (1)
- gelatin (1)
- gene silencing (1)
- glass (1)
- glucose homeostasis (1)
- glucosinolates (1)
- glycosynthases (1)
- gold (1)
- gold nanoparticles (1)
- gold nanotriangles (1)
- habitat (1)
- head-to-tail surfactant associates (1)
- helicenes (1)
- hemodialysis (1)
- hepcidin-25 (1)
- hybrid perovskites (1)
- hydrogel (1)
- hydrolysis (1)
- hydroxycinnamic acids (1)
- hypothalamus (1)
- immunoassay (1)
- in situ (1)
- ion beam (1)
- ionic strength (1)
- lanthanides (1)
- liposomes (1)
- low-energy electron (1)
- low-energy electrons (1)
- lupin (1)
- macrocycles (1)
- maleimide (1)
- mass spectrometry (1)
- materials science (1)
- membranes (1)
- metal complex (1)
- metal peptide (1)
- metallopeptide (1)
- metalloprotein (1)
- methylmercury (1)
- microbial activity (1)
- microgreen (1)
- microstructure (1)
- mild reaction conditions (1)
- miscibility gap (1)
- mitochondria (1)
- mold fungi (1)
- molecular weight (1)
- multiblock copolymer (1)
- multivalent ions (1)
- nanoarray (1)
- nanostructure fabrication (1)
- nanostructures (1)
- near-infrared absorption (1)
- neuropeptides (1)
- nickel (1)
- nitriles (1)
- o-Phenylenediamine (1)
- olefin metathesis (1)
- oligodepsipeptides (1)
- ontogeny (1)
- organocatalytic polymerization (1)
- oxygen plasma (1)
- pH sensing (1)
- pH-responsive (1)
- palmitoylation (1)
- pea (1)
- perovskite solar cells (1)
- photocatalytic water splitting (1)
- photocycloaddition (1)
- photodehydro-Diels-Alder reaction (1)
- photoluminescence (1)
- photolytic ablation (1)
- photonic crystals (1)
- poly(epsilon-caprolactone) (1)
- poly(lactic acid) (1)
- poly(n-butyl acrylate) (1)
- polylactide (1)
- polymer degradation (1)
- polymerization (1)
- polymyrcene (1)
- polystyrene (1)
- polysulfabetaine (1)
- polysulfobetaine (1)
- polyzwitterions (1)
- potassium (1)
- powder diffraction (1)
- prenylated flavanonol (1)
- probes (1)
- protein analysis (1)
- protein self-assembly (1)
- purity (1)
- racemization (1)
- radicals (1)
- radiosensitizers (1)
- ratiometric sensing (1)
- ratiometric sensors (1)
- reference (1)
- reference material (1)
- regioselectivity (1)
- renewable resource (1)
- rubidium cation (1)
- scale-up (1)
- scatchard plot (1)
- selective oxidations (1)
- self-healing (1)
- sesquiterpene (1)
- shape-memory effect (1)
- shape-memory polymer actuators (1)
- silkworm silk (1)
- silver nanoparticles (1)
- silver(1) complexes (1)
- singlet oxygen (1)
- skin equivalents (1)
- soft X-radiation (1)
- soft actuators (1)
- soft matter micro- and nanowires (1)
- sortase-mediated ligation (1)
- spectro-electrochemistry (1)
- spider silk (1)
- sputtering (1)
- stereocomplexation (1)
- streptavidin (1)
- structure elucidation (1)
- subtriflavanonol (1)
- superparamagnetic (1)
- supramolecular interactions (1)
- surface enhanced spectroscopy (1)
- surface-enhanced Raman spectroscopy (1)
- synthetic methods (1)
- telechelics (1)
- telomeric DNA (1)
- thermal processing of food (1)
- thermoplastics (1)
- thermoresponsive-nanogel (1)
- thiol-ene (1)
- tin(II) 2-ethylhexanoate (1)
- titania (1)
- topical (1)
- ultra-fast laser inscription (1)
- undulated nanoplatelets (1)
- upconversion (1)
- viability (1)
- volatile organic compounds (1)
- yolk-shell nanoparticles (1)
Institute
- Institut für Chemie (140) (remove)
Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H-2 and O-2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl-2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O-2 generation from water was verified by O-18 isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.
What is the underlying diffusion process governing the spreading dynamics and search strategies employed by amoeboid cells? Based on the statistical analysis of experimental single-cell tracking data of the two-dimensional motion of the Dictyostelium discoideum amoeboid cells, we quantify their diffusive behaviour based on a number of standard and complementary statistical indicators. We compute the ensemble- and time-averaged mean-squared displacements (MSDs) of the diffusing amoebae cells and observe a pronounced spread of short-time diffusion coefficients and anomalous MSD-scaling exponents for individual cells. The distribution functions of the cell displacements, the long-tailed distribution of instantaneous speeds, and the velocity autocorrelations are also computed. In particular, we observe a systematic superdiffusive short-time behaviour for the ensemble- and time-averaged MSDs of the amoeboid cells. Also, a clear anti-correlation of scaling exponents and generalised diffusivity values for different cells is detected. Most significantly, we demonstrate that the distribution function of the cell displacements has a strongly non-Gaussian shape andusing a rescaled spatio-temporal variablethe cell-displacement data collapse onto a universal master curve. The current analysis of single-cell motions can be implemented for quantifying diffusive behaviours in other living-matter systems, in particular, when effects of active transport, non-Gaussian displacements, and heterogeneity of the population are involved in the dynamics.
The generation of reactive singlet oxygen under mild conditions is of current interest in chemistry, biology, and medicine. We were able to release oxygen from dipyridylanthracene endoperoxides (EPOs) by using a simple chemical trigger at low temperature. Protonation and methylation of such EPOs strongly accelerated these reactions. Furthermore, the methyl pyridinium derivatives are water soluble and therefore serve as oxygen carriers in aqueous media. Methylation of the EPO of the ortho isomer affords the parent form directly without increasing the temperature under very mild conditions. This exceptional behavior is ascribed to the close contact between the nitrogen atom and the peroxo group. Singlet oxygen is released upon this reaction, and can be used to oxygenate an acceptor such as tetramethylethylene in the dark with no heating. Thus, a new chemical source of singlet oxygen has been found, which is triggered by a simple stimulus.
We use clusters for the modeling of local ion resonances caused by low energy charge carriers in STM-induced desorption of benzene derivates from Si(111)-7 x 7. We perform Born-Oppenheimer molecular dynamics for the charged systems assuming vertical transitions to the charged states at zero temperature, to rationalize the low temperature activation energies, which are found in experiment for chlorobenzene. Our calculations suggest very similar low temperature activation energies for toluene and benzene. For the cationic resonance transitions to physisorption are found even at 0 K, while the anion remains chemisorbed during the propagations. Further, we also extend our previous static quantum chemical investigations to toluene and benzene. In addition, an in depth analysis of the ionization potentials and electron affinities, which are used to estimate resonance energies, is given.
Boric acid and sodium borates are currently classified in the EU-CLP regulation as "toxic to reproduction" under "Category 1B", with hazard statement of H360FD. However, so far field studies on male reproduction in China and in Turkey could not confirm such boron-associated toxic effects. As validation by another independent study is still required, the present study has investigated possible boron-associated effects on male reproduction in workers (n = 212) under different boron exposure conditions. The mean daily boron exposure (DBE) and blood boron concentration of workers in the extreme exposure group (n = 98) were 47.17 +/- 17.47 (7.95-106.8) mg B/day and 570.6 +/- 160.1 (402.6-1100) ng B/g blood, respectively. Nevertheless, boron-associated adverse effects on semen parameters, as well as on FSH, LH and total testosterone levels were not seen, even within the extreme exposure group. With this study, a total body of evidence has accumulated that allows to conclude that male reproductive effects are not relevant to humans, under any feasible and realistic conditions of exposure to inorganic boron compounds.
Hypothesis: An effective way for fixating vesicle structures is the insertion of monomers and cross-linking agents into their bilayer, and their subsequent polymerization can lead to the formation of polymeric nanocapsules. Particularly attractive here are vesicle systems that form spontaneously well-defined small vesicles, as obtaining such small nanocapsules with sizes below 100 nm is still challenging. Experiments: A spontaneously forming well-defined vesicle system composed of the surfactants TDMAO (tetradecyldimethylamine oxide), Pluronic L35, and LiPFOS (lithium perfluorooctylsulfonate) mixture was used as template for fixation by polymerization. Therefore, styrene monomer was incorporated into the vesicle bilayer and ultimately these structures were fixated by UV induced radical polymerization. Structural alteration of the vesicles upon loading with monomer and the cross-linker as well as the effect of subsequent polymerization in the membrane were investigated in detail by turbidity measurements, dynamic and static light scattering, (DLS, SLS), and small angle neutron scattering (SANS). Findings: The analysis showed the changes on vesicle structures due to the monomer loading, and that these structures can become permanently fixed by the polymerization process. The potential of this approach to produce well-defined nanocapsules starting from a self-assembled system and following polymerization is critically evaluated. (C) 2018 Elsevier Inc. All rights reserved.
We report ultrasonically generated pH-responsive Pickering Janus emulsions of olive oil and silicone oil with controllable droplet size and engulfment. Chitosan was used as a pH-responsive emulsifier. The increase of pH from 2 to 6 leads to a transition from completely engulfed double emulsion droplets to dumbbell-shaped Janus droplets accompanied by a significant decrease of droplet diameter and a more homogeneous size distribution. The results can be elucidated by the conformational change of chitosan from a more extended form at pH 2 to a more flexible form at pH 4-5. Magnetic responsiveness to the emulsion was attributed by dispersing superparamagnetic nanoparticles (Fe3O4 with diameter of 13 +/- 2 nm) in the olive oil phase before preparing the Janus emulsion. Incorporation of magnetic nanoparticles leads to superior emulsion stability, drastically reduced droplet diameters, and opened the way to control movement and orientation of the Janus droplets according to an external magnetic field.
Hepcidin-25 was identified as themain iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II) binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandemmass spectrometry (MS/MS), high-resolutionmass spectrometry (HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or referencematerial comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.
Femtosecond-Pulsed laser written and etched fiber bragg gratings for fiber-optical biosensing
(2018)
We present the development of a label-free, highly sensitive fiber-optical biosensor for online detection and quantification of biomolecules. Here, the advantages of etched fiber Bragg gratings (eFBG) were used, since they induce a narrowband Bragg wavelength peak in the reflection operation mode. The gratings were fabricated point-by-point via a nonlinear absorption process of a highly focused femtosecond-pulsed laser, without the need of prior coating removal or specific fiber doping. The sensitivity of the Bragg wavelength peak to the surrounding refractive index (SRI), as needed for biochemical sensing, was realized by fiber cladding removal using hydrofluoric acid etching. For evaluation of biosensing capabilities, eFBG fibers were biofunctionalized with a single-stranded DNA aptamer specific for binding the C-reactive protein (CRP). Thus, the CRP-sensitive eFBG fiber-optical biosensor showed a very low limit of detection of 0.82 pg/L, with a dynamic range of CRP detection from approximately 0.8 pg/L to 1.2 mu g/L. The biosensor showed a high specificity to CRP even in the presence of interfering substances. These results suggest that the proposed biosensor is capable for quantification of CRP from trace amounts of clinical samples. In addition, the adaption of this eFBG fiber-optical biosensor for detection of other relevant analytes can be easily realized.
As part of a project studying the secondary metabolites extracted from the Chilean flora, we report herein three new beta-agarofuran sesquiterpenes, namely (1S,4S,5S,6R,7R,8R,9R,10S)-6-acetoxy-4,9-dihydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b] oxepine-5,10-diylbis(furan-3-carboxylate), C27H32O11, (II), (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-9-hydroxy-2,2,5a, 9-tetramethyloctahydro-2H-3,9a-methanobenzo[ b] oxepine-5,10-diyl bis(furan-3-carboxylate), C27H32O10, (III), and (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-10-(benzoyloxy)-9-hydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b]oxepin-5-yl furan-3-carboxylate, C29H34O9, (IV), obtained from the seeds of Maytenus boaria and closely associated with a recently published relative [Paz et al. (2017). Acta Cryst. C73, 451-457]. In the (isomorphic) structures of (II) and (III), the central decalin system is esterified with an acetate group at site 1 and furoate groups at sites 6 and 9, and differ at site 8, with an OH group in (II) and no substituent in (III). This position is also unsubstituted in (IV), with site 6 being occupied by a benzoate group. The chirality of the skeletons is described as 1S, 4S, 5S, 6R, 7R, 8R, 9R, 10S in (II) and 1S, 4S, 5S, 6R, 7R, 9S, 10S in (III) and (IV), matching the chirality suggested by NMR studies. This difference in the chirality sequence among the title structures (in spite of the fact that the three skeletons are absolutely isostructural) is due to the differences in the environment of site 8, i.e. OH in (II) and H in (III) and (IV). This diversity in substitution, in turn, is responsible for the differences in the hydrogen-bonding schemes, which is discussed.