Vivek Sinha, Fateme Rezai, Nihat Ege Sahin, Jacopo Catalano, Espen Drath Bøjesen, Farnaz Sotoodeh, Emil Dražević (2023). Electrochemical nitrogen reduction reaction over gallium – a computational and experimental study . Faraday Discussions.

Vivek Sinha, Annika M. Krieger, Guanna Li, Evgeny A. Pidko(2022). Solvent-Assisted Ketone Reduction by a Homogeneous Mn Catalyst . Organometallics. American Chemical Society ({ACS})

Vivek Sinha, Anirudh Venugopal, Laurentius H. T. Egberts, Jittima Meeprasert, Evgeny A. Pidko, Bernard Dam, Thomas Burdyny, Wilson A. Smith(2022). Polymer Modification of Surface Electronic Properties of Electrocatalysts . ACS Energy Letters. 7. (5). p. 1586--1593. American Chemical Society ({ACS})

Venugopal, A., Egberts, L.H.T., Meeprasert, J., Pidko, E.A., Dam, B., Burdyny, T., Sinha, V., Smith, W.A.(2022). Polymer Modification of Surface Electronic Properties of Electrocatalysts . ACS Energy Letters. p. 1586-1593.

Vivek Sinha, Adarsh V. Kalikadien, Evgeny A. Pidko (2022). ChemSpaX: exploration of chemical space by automated functionalization of molecular scaffold . Digital Discovery.

Vivek Sinha, Felix J. de Zwart, Monica Trincado, Hansjörg Grützmacher, Bas de Bruin (2022). Computational mechanistic studies of ruthenium catalysed methanol dehydrogenation . Dalton Transactions.

De Zwart, F.J., Sinha, V., Trincado, M., Grützmacher, H., De Bruin, B.(2022). Computational mechanistic studies of ruthenium catalysed methanol dehydrogenation . Dalton Transactions. 51. (8). p. 3019-3026.

Vivek Sinha, Elena Khramenkova, Evgeny A. Pidko(2022). Solvent-mediated outer-sphere CO2 electro-reduction mechanism over the Ag111 surface . Chemical Science. 13. (13). p. 3803--3808. Royal Society of Chemistry ({RSC})

Sinha, V., Khramenkova, E., Pidko, E.A.(2022). Solvent-mediated outer-sphere CO₂ electro-reduction mechanism over the Ag111 surface . Chemical Science. 13. (13). p. 3803-3808.

Vivek Sinha, Alex S. Tossaint, Christophe Rebreyend, Manuela Weber, Stefano Canossa, Evgeny A. Pidko, Georgy A. Filonenko(2022). Two step activation of Ru-PN3P pincer catalysts for CO2 hydrogenation . Catalysis Science & Technology. Royal Society of Chemistry ({RSC})

Tossaint, A.S., Rebreyend, C., Sinha, V., Weber, M., Canossa, S., Pidko, E.A., Filonenko, G.A.(2022). Two step activation of Ru-PN³P pincer catalysts for CO₂ hydrogenation . Catalysis Science and Technology.

Krieger, A.M., Sinha, V., Li, G., Pidko, E.A.(2022). Solvent-Assisted Ketone Reduction by a Homogeneous Mn Catalyst . Organometallics. 41. (14). p. 1829-1835.

Vivek Sinha, Qiuhua Liang, Geert Brocks, Anja Bieberle‐Hütter(2021). Cover Feature: Tailoring the Performance of ZnO for Oxygen Evolution by Effective Transition Metal Doping (ChemSusChem 15/2021) . ChemSusChem. Wiley

Vivek Sinha, Qiuhua Liang, Geert Brocks, Anja Bieberle‐Hütter(2021). Tailoring the Performance of ZnO for Oxygen Evolution by Effective Transition Metal Doping . ChemSusChem. Wiley

Vivek Sinha, Annika M. Krieger, Adarsh V. Kalikadien, Evgeny A. Pidko(2021). Metal‐ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes . Zeitschrift für anorganische und allgemeine Chemie. 647. (14). p. 1486--1494. Wiley

Vivek Sinha, Annika M. Krieger, Adarsh V. Kalikadien, Evgeny A. Pidko(2021). Front Cover: Metal‐ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes (14/2021) . Zeitschrift für anorganische und allgemeine Chemie. 647. (14). p. 1397--1397. Wiley

Vivek Sinha, Felix J. de Zwart, Bente Reus, Annechien A.H. Laporte, Bas de Bruin(2021). Metrical Oxidation States of 1,4-Diazadiene-Derived Ligands . Inorganic Chemistry. 60. (5). p. 3274--3281. American Chemical Society ({ACS})

De Zwart, F.J., Reus, B., Laporte, A.A.H., Sinha, V., De Bruin, B.(2021). Metrical Oxidation States of 1,4-Diazadiene-Derived Ligands . Inorganic Chemistry. 60. (5). p. 3274-3281.

Vivek Sinha, Jochem J. Laan, Evgeny A. Pidko(2021). Accurate and rapid prediction of pKa of transition metal complexes: semiempirical quantum chemistry with a data-augmented approach . Physical Chemistry Chemical Physics. Royal Society of Chemistry ({RSC})

Sinha, V., Laan, J.J., Pidko, E.A.(2021). Accurate and rapid prediction of pK_aof transition metal complexes: semiempirical quantum chemistry with a data-augmented approach . Physical Chemistry Chemical Physics. 23. (4). p. 2557-2567.

Anand, Megha and Baletto, Francesca and Bugaev, Aram and Catlow, Richard and Claeys, Michael and Conway, Matthew and Davidson, Matthew and Davies, Philip and de Leeuw, Nora and Eremin, Dmitry and Fischer, Nico and Hargreaves, Justin and Hutchings, Graham and Iyer, Jayendran and Jain, Disha and Jameel, Froze and Kamali, Ali Reza and Kondrat, Simon and Kowalec, Igor and Kraus, Peter and Reece, Christian and Réocreux, Romain and Santos-Carballal, David and Seavill, Peter W. and Shozi, Mzamo and Sinev, Mikhail and Sinha, Vivek and Stamatakis, Michail and Uner, Deniz and Vojvodic, Aleksandra and Whiston, Keith and Willock, David and Wolf, Moritz and Yang, Bo and Zhu, Beien(2021). Theory: general discussion . Faraday Discuss. p. -. The Royal Society of Chemistry

Anand, M., Baletto, F., Bugaev, A., Catlow, R., Claeys, M., Conway, M., Davidson, M., Davies, P., De Leeuw, N., Eremin, D., et al.(2021). Theory: General discussion . Faraday Discussions. 229. p. 131-160.

V. Sinha, D. Sun, E. J. Meijer, T. J. H. Vlugt, A. Bieberle-Hütter(2021). A multiscale modelling approach to elucidate the mechanism of the oxygen evolution reaction at the hematite–water interface . Faraday Discussions. 229. p. 89--107. Royal Society of Chemistry ({RSC})

Sinha, V., Sun, D., Meijer, E.J., Vlugt, T.J.H., Bieberle-Hutter, A.(2021). A multiscale modelling approach to elucidate the mechanism of the oxygen evolution reaction at the hematite-water interface . Faraday Discussions. 229. p. 89-107.

Krieger, A.M., Sinha, V., Kalikadien, A.V., Pidko, E.A.(2021). Metal-ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes . Zeitschrift fur Anorganische und Allgemeine Chemie. 647. (14). p. 1486-1494.

Liang, Q., Brocks, G., Sinha, V., Bieberle-Hütter, A.(2021). Tailoring the Performance of ZnO for Oxygen Evolution by Effective Transition Metal Doping . ChemSusChem. 14. (15). p. 3064-3073.

Vivek Sinha, Kiran George, Tigran Khachatrjan, Matthijs van Berkel, Anja Bieberle-Hütter(2020). Understanding the Impact of Different Types of Surface States on Photoelectrochemical Water Oxidation: A Microkinetic Modeling Approach . ACS Catalysis. 10. (24). p. 14649--14660. American Chemical Society ({ACS})

Vivek Sinha, Nitish Govindarajan, Monica Trincado, Hansjörg Grützmacher, Evert Jan Meijer, Bas de Bruin (2020). An In‐Depth Mechanistic Study of Ru‐Catalysed Aqueous Methanol Dehydrogenation and Prospects for Future Catalyst Design . ChemCatChem.

Govindarajan, N., Sinha, V., Trincado, M., Grützmacher, H., Meijer, E.J., de Bruin, B.(2020). An In-Depth Mechanistic Study of Ru-Catalysed Aqueous Methanol Dehydrogenation and Prospects for Future Catalyst Design . ChemCatChem. 12. (9). p. 2610-2621.

(2020). A Multiscale Modelling Approach to Elucidate the Mechanism of the Oxygen Evolution Reaction at the Hematite-Water Interface . Faraday Discussions.

George, K., Khachatrjan, T., van Berkel, M., Sinha, V., Bieberle-Hütter, A.(2020). Understanding the impact of different types of surface states on photoelectrochemical water oxidation: A microkinetic modeling approach . ACS Catalysis. 10. (24). p. 14649-14660.

(2019). Rational Redesign of a Regioselective Hydroformylation Catalyst for 3‐Butenoic Acid by Supramolecular Substrate Orientation . ChemCatChem.

Vivek Sinha, Suman Sinha, Rina Sikari, Upasona Jash, Siuli Das, Paula Brandão, Serhiy Demeshko, Franc Meyer, Bas de Bruin, Nanda D. Paul(2019). Iron-Catalyzed/Mediated C–N Bond Formation: Competition between Substrate Amination and Ligand Amination . Inorganic Chemistry. 58. (3). p. 1935--1948. American Chemical Society ({ACS})

(2019). Effector responsive hydroformylation catalysis . Chemical Science.

Sinha, S., Sikari, R., Sinha, V., Jash, U., Das, S., Brandão, P., Demeshko, S., Meyer, F., De Bruin, B., Paul, N.D.(2019). Iron-Catalyzed/Mediated C-N Bond Formation: Competition between Substrate Amination and Ligand Amination . Inorganic Chemistry. 58. (3). p. 1935-1948.

Bai, S.-T., Sinha, V., Kluwer, A.M., Linnebank, P.R., Abiri, Z., Dydio, P., Lutz, M., De Bruin, B., Reek, J.N.H.(2019). Effector responsive hydroformylation catalysis . Chemical Science. 10. (31). p. 7389-7398.

Bai, S.-T., Sinha, V., Kluwer, A.M., Linnebank, P.R., Abiri, Z., de Bruin, B., Reek, J.N.H.(2019). Rational Redesign of a Regioselective Hydroformylation Catalyst for 3-Butenoic Acid by Supramolecular Substrate Orientation . ChemCatChem. 11. (21). p. 5322-5329.

Vivek Sinha, Monica Trincado, Hansjörg Grützmacher, Bas de Bruin(2018). DFT Provides Insight into the Additive-Free Conversion of Aqueous Methanol to Dihydrogen Catalyzed by [Ru(trop2dad)]: Importance of the (Electronic) Flexibility of the Diazadiene Moiety . Journal of the American Chemical Society. 140. (40). p. 13103--13114. American Chemical Society ({ACS})

Sinha, V., Trincado, M., Grützmacher, H., De Bruin, B.(2018). Correction: dFT Provides Insight into the Additive-Free Conversion of Aqueous Methanol to Dihydrogen Catalyzed by [Ru(trop ₂ dad)]: Importance of the (Electronic) Flexibility of the Diazadiene Moiety (Journal of the American Chemical Society (2018) 140 (13103-13114) DOI: 10.1021/jacs.8b09011) . Journal of the American Chemical Society. 140. (48). p. 16865-16866.

Sinha, V., Govindarajan, N., De Bruin, B., Meijer, E.J.(2018). How Solvent Affects C-H Activation and Hydrogen Production Pathways in Homogeneous Ru-Catalyzed Methanol Dehydrogenation Reactions . ACS Catalysis. 8. (8). p. 6908-6913.

Sinha, V., Pribanic, B., de Bruin, B., Trincado, M., Grützmacher, H.(2018). Ligand- and Metal-Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious . Chemistry - A European Journal. 24. (21). p. 5400.

Sinha, V., Trincado, M., Grützmacher, H., De Bruin, B.(2018). DFT Provides Insight into the Additive-Free Conversion of Aqueous Methanol to Dihydrogen Catalyzed by [Ru(trop₂dad)]: Importance of the (Electronic) Flexibility of the Diazadiene Moiety . Journal of the American Chemical Society. 140. (40). p. 13103-13114.

Sinha, V., Pribanic, B., de Bruin, B., Trincado, M., Grützmacher, H.(2018). Ligand- and Metal-Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious . Chemistry - A European Journal. 24. (21). p. 5513-5521.

How Solvent Affects C–H Activation and Hydrogen Production Pathways in Homogeneous Ru-Catalyzed Methanol Dehydrogenation Reactions @article{doi:10.1021/acscatal.8b01177, author= {Sinha, Vivek and Govindarajan, Nitish and de Bruin, Bas and Meijer, Evert Jan}, title= {How Solvent Affects C–H Activation and Hydrogen Production Pathways in Homogeneous Ru-Catalyzed Methanol Dehydrogenation Reactions}, journal= {ACS Catalysis}, volume= {8}, number= {8}, pages= {6908-6913}, year= {2018}, doi= {10.1021/acscatal.8b01177}, URL= {https://doi.org/10.1021/acscatal.8b01177 }, eprint= {https://doi.org/10.1021/acscatal.8b01177 }} . ACS Catalysis.

(2017). Homogeneously catalysed conversion of aqueous formaldehyde to H2 and carbonate . Nature communications.

Bagh, B., Broere, D.L.J., Sinha, V., Kuijpers, P.F., Van Leest, N.P., De Bruin, B., Demeshko, S., Siegler, M.A., Van Der Vlugt, J.I.(2017). Catalytic Synthesis of N-Heterocycles via Direct C(sp ³ )-H Amination Using an Air-Stable Iron(III) Species with a Redox-Active Ligand . Journal of the American Chemical Society. 139. (14). p. 5117-5124.

Trincado, M., Sinha, V., Rodriguez-Lugo, R.E., Pribanic, B., De Bruin, B., Grützmacher, H.(2017). Homogeneously catalysed conversion of aqueous formaldehyde to H₂ and carbonate . Nature Communications. 8.

Catalytic Synthesis of N-Heterocycles via Direct C(sp3)–H Amination Using an Air-Stable Iron(III) Species with a Redox-Active Ligand @article{doi:10.1021/jacs.7b00270, author= {Bagh, Bidraha and Broere, Daniël L. J. and Sinha, Vivek and Kuijpers, Petrus F. and van Leest, Nicolaas P. and de Bruin, Bas and Demeshko, Serhiy and Siegler, Maxime A. and van der Vlugt, Jarl Ivar}, title= {Catalytic Synthesis of N-Heterocycles via Direct C(sp3)–H Amination Using an Air-Stable Iron(III) Species with a Redox-Active Ligand}, journal= {Journal of the American Chemical Society}, volume= {139}, number= {14}, pages= {5117-5124}, year= {2017}, doi= {10.1021/jacs.7b00270}, note= {PMID: 28298089}, URL= {http://dx.doi.org/10.1021/jacs.7b00270 }, eprint= {http://dx.doi.org/10.1021/jacs.7b00270 }} . Journal of the American Chemical Society.

(2014). CO adsorption on FeN(N=1–4) transition metal clusters: a density functional theory study .

Vivek Sinha and Mahesh Sundararajan(2014). Structure and cation binding affinities of cucurbit[6]uril: A DFT study . AIP Conference Proceedings. 1591. (1). p. 1708-1710.

Sinha, V., Ghorai, P.K.(2014). CO adsorption on Fe_N(N = 1-4) transition metal clusters: A density functional theory study . Current Science. 106. (9). p. 1243-1248.

Energetics of Ortho-7 (Oxime Drug) Translocation through the Active-Site Gorge of Tabun Conjugated Acetylcholinesterase @article{10.1371/journal.pone.0040188, author= {Sinha, Vivek AND Ganguly, Bishwajit AND Bandyopadhyay, Tusar}, journal= {PLOS ONE}, publisher= {Public Library of Science}, title= {Energetics of Ortho-7 (Oxime Drug) Translocation through the Active-Site Gorge of Tabun Conjugated Acetylcholinesterase}, year= {2012}, month= {07}, volume= {7}, url= {https://doi.org/10.1371/journal.pone.0040188}, pages= {1-14}, abstract= {Oxime drugs translocate through the 20 Å active-site gorge of acetylcholinesterase in order to liberate the enzyme from organophosphorus compounds’ (such as tabun) conjugation. Here we report bidirectional steered molecular dynamics simulations of oxime drug (Ortho-7) translocation through the gorge of tabun intoxicated enzyme, in which time dependent external forces accelerate the translocation event. The simulations reveal the participation of drug-enzyme hydrogen bonding, hydrophobic interactions and water bridges between them. Employing nonequilibrium theorems that recovers the free energy from irreversible work done, we reconstruct potential of mean force along the translocation pathway such that the desired quantity represents an unperturbed system. The potential locates the binding sites and barriers for the drug to translocate inside the gorge. Configurational entropic contribution of the protein-drug binding entity and the role of solvent translational mobility in the binding energetics is further assessed.}, number= {7}, doi= {10.1371/journal.pone.0040188}} . PLOS ONE.

Sundararajan, Mahesh and Sinha, Vivek and Bandyopadhyay, Tusar and Ghosh, Swapan K.(2012). Can Functionalized Cucurbituril Bind Actinyl Cations Efficiently? A Density Functional Theory Based Investigation . The Journal of Physical Chemistry A. 116. (17). p. 4388-4395.

Sundararajan, M., Sinha, V., Bandyopadhyay, T., Ghosh, S.K.(2012). Can functionalized cucurbituril bind actinyl cations efficiently? a density functional theory based investigation . Journal of Physical Chemistry A. 116. (17). p. 4388-4395.

Sinha, V., Ganguly, B., Bandyopadhyay, T.(2012). Energetics of ortho-7 (oxime drug) translocation through the active-site gorge of tabun conjugated acetylcholinesterase . PLoS ONE. 7. (7).

Ligand‐ and Metal‐Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious @article{doi:10.1002/chem.201705957, author= {Sinha Vivek and Pribanic Bruno and de Bruin Bas and Trincado Monica and Grützmacher Hansjörg}, title= {Ligand‐ and Metal‐Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious}, journal= {Chemistry – A European Journal}, volume= {24}, number= {21}, pages= {5513-5521}, keywords= {azides, olefin ligands, redox chemistry, ruthenium, synthetic methods}, doi= {10.1002/chem.201705957}, url= {https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201705957}, eprint= {https://onlinelibrary.wiley.com/doi/pdf/10.1002/chem.201705957}, abstract= {Abstract Coordination of the diazadiene diolefin ligand (trop2dad) to ruthenium leads to various complexes of composition [Ru(trop2dad)(L)]. DFT studies indicate that the closed‐shell singlet (CSS), open‐shell singlet (OSS), and triplet electronic structures of this species are close in energy, with the OSS spin configuration being the lowest in energy for all tested functionals. Singlet‐state CASSCF calculations revealed a significant multireference character for these complexes. The closed‐shell singlet wavefunction dominates, but these complexes have a significant (≈8–16 \%) open‐shell singlet [d7‐RuI(L)(trop2dad.−)] contribution mixed into the ground state. In agreement with their ambivalent electronic structure, these complexes reveal both metal‐ and ligand‐centered reactivity. Most notable are the reactions with AdN3, diazomethane, and a phosphaalkyne leading to scission of the C−C bond of the diazadiene (dad) moiety of the trop2dad ligand, resulting in net (formal) nitrene, carbene, or P≡C insertion in the dad C−C bond, respectively. Supporting DFT studies revealed that several of the ligand‐based reactions proceed via low‐barrier radical‐type pathways, involving the dad.− ligand radical character of the OSS or triplet species.}} . Chemistry – A European Journal.

Liang, Qiuhua and Brocks, Geert and Sinha, Vivek and Bieberle, Anja Tailoring the performance of ZnO for oxygen evolution by effective transition metal doping . ChemSusChem. n/a. (n/a).

Metal-ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes @article{https://doi.org/10.1002/zaac.202100078, author= {Krieger, Annika and Sinha, Vivek and Kalikadien, Adarsh and Pidko, Evgeny Alexandrovich}, title= {Metal-ligand cooperative activation of HX (X=H, Br, OR) bond on Mn based pincer complexes}, journal= {Zeitschrift für anorganische und allgemeine Chemie}, volume= {n/a}, number= {n/a}, pages= {}, keywords= {computational catalysis, linear scaling relations, manganese catalysis, metal-ligand cooperation, deactivation}, doi= {https://doi.org/10.1002/zaac.202100078}, url= {https://onlinelibrary.wiley.com/doi/abs/10.1002/zaac.202100078}, eprint= {https://onlinelibrary.wiley.com/doi/pdf/10.1002/zaac.202100078}, abstract= {Reversible dissociation of H-X bond (M-L + H-X → M(X)-L(H); [[EQUATION]] ) is an important step during pre-activation, catalysis and possible deactivation of acid-base cooperative pincer based transition metal catalysts (M-L). Herein we carried out a high-throughput computational investigation of the thermodynamic stability of different adducts in various functionalized Mn(I) based pincer complexes. We used a combination of density functional theory (DFT) and density functional tight binding (DFTB) calculations to analyze [[EQUATION]] of > 700 (M(X)-L(H)) intermediates based on functionalized variants of four pincer type ligand scaffolds derived from PCP, CNC, PNP and SNS ligands. We discovered linear scaling relations between [[EQUATION]] of various species. Strongest correlations were found between species of similar size and chemical nature e.g. [[EQUATION]] correlated best with [[EQUATION]] and worst with [[EQUATION]] . Such scaling relations can be useful for property based screening of catalysts and selection of (co)solvent/substrate/base for optimized reaction conditions. We also investigated the influence of the ligand backbone and the functionalization of donor and backbone sites in the ligand. Our analysis reveals the crucial role of the second coordination sphere functionalization for the reactivity of the complexes with impact in some cases exceeding that of the variation of the functional groups directly attached to the donor atoms.}} . Zeitschrift für anorganische und allgemeine Chemie.

Tossain, A.S., Rebreyend, C., Sinha, V., Weber, M., Canossa, S., Pidko, E.A., Filonenko, G.A.(2022). Two step activation of Ru-PN³P pincer catalysts for CO₂hydrogenation . ChemRxiv.

Kalikadien, A.V., Pidko, E.A., Sinha, V.(2021). ChemSpaX: Exploration of chemical space by automated functionalization of molecular scaffold . ChemRxiv.

Sinha, V., Laan, J.J., Pidko, E.A.(2020). Accurate and Rapid Prediction of pK_a of Transition Metal Complexes: Semiempirical Quantum Chemistry with a DataAugmented Approach . ChemRxiv.

de Zwart, F.J., Reus, B., Laporte, A.A.H., Sinha, V., de Bruin, B.(2020). Metrical oxidation states of 1,4-diazadiene (DAD) derived ligands . ChemRxiv.

Govindarajan, N., Sinha, V., Trincado, M., Grützmacher, H., Meijer, E.J., de Bruin, B.(2019). An in-depth mechanistic study of Ru catalysed aqueous methanol dehydrogenation and prospects for future catalyst design . ChemRxiv.

Vivek Sinha, Adarsh Kalikadien, Evgeny A. Pidko (2021). ChemSpaX: Exploration of Chemical Space by Automated Functionalization of Molecular Scaffold .

Vivek Sinha, Jochem Jan Laan, Evgeny Pidko (2020). Accurate and Rapid Prediction of pKa of Transition Metal Complexes: Semiempirical Quantum Chemistry with a DataAugmented Approach .

(2018). Application of Stimuli-Responsive and “Non-innocent” Ligands in Base Metal Catalysis . Non-Noble Metal Catalysis.

Sinha, V., Sundararajan, M.(2014). Structure and cation binding affinities of cucurbit[6]uril: A DFT study . AIP Conference Proceedings. 1591. p. 1708-1710.