Computational and Theoretical Chemistry最新文献_第9页

Computational investigation into the structure, effect of band gap energies, charge transfer, reactivity, thermal energies and NADPH inhibitory activity of a benzimidazole derivative 对苯并咪唑衍生物的结构、带隙能效应、电荷转移、反应性、热能和 NADPH 抑制活性的计算研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-03 DOI: 10.1016/j.comptc.2024.114908

R. Abhijith , Riya Datta , S. Sakthivel , Jamal M. Khaled , S. Muthu

{"title":"Computational investigation into the structure, effect of band gap energies, charge transfer, reactivity, thermal energies and NADPH inhibitory activity of a benzimidazole derivative","authors":"R. Abhijith , Riya Datta , S. Sakthivel , Jamal M. Khaled , S. Muthu","doi":"10.1016/j.comptc.2024.114908","DOIUrl":"10.1016/j.comptc.2024.114908","url":null,"abstract":"<div><div>This work contains computational investigations of a benzimidazole derivative consisting of density functional theory, electronic structure and biological evaluation of a benzimidazole derivative. Density functional theory evaluation were conducted, starting from geometry optimisation, followed by the molecular electrostatic potential, spectral analyses, polarizability studies and thermodynamic analyses via the frequency calculations. Solvent frontier molecular orbital analyses, impact on the properties of the molecule were modelled with the IEFPCM model of solvation. Topological analyses helped to ascertain the molecule’s electronic structure. Biological assessment included pharmacokinetic property evaluation and molecular docking. Pharmacokinetic descriptors were generated using online tools and the molecule was assessed for its efficacy as a drug molecule by comparing with the rules concerning drug-likeness and analysing the descriptors relating to absorption, distribution, metabolism, excretion and toxicity of the molecule. Docking of the molecule with the two targets, 7D3E and 3A1F, yielded a good binding energy of −7.39 and −5.81 kcal/mol respectively.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114908"},"PeriodicalIF":3.0,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Peculiar trapping behavior of porous organic nanocage CC1 towards H2S, SF6, SF4, SOCl2 and SO2; A DFT Perspective 多孔有机纳米笼 CC1 对 H2S、SF6、SF4、SOCl2 和 SO2 的奇特捕集行为；DFT 观点

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-03 DOI: 10.1016/j.comptc.2024.114898

Sadia Rani , Riaz Hussain , Samina Aslam , Sehrish Sarfaraz , Ajaz Hussain , Muhammad Durair Sajjad Haider , Mirza Arfan Yawer , Muhammad Imran , Khurshid Ayub

{"title":"Peculiar trapping behavior of porous organic nanocage CC1 towards H2S, SF6, SF4, SOCl2 and SO2; A DFT Perspective","authors":"Sadia Rani , Riaz Hussain , Samina Aslam , Sehrish Sarfaraz , Ajaz Hussain , Muhammad Durair Sajjad Haider , Mirza Arfan Yawer , Muhammad Imran , Khurshid Ayub","doi":"10.1016/j.comptc.2024.114898","DOIUrl":"10.1016/j.comptc.2024.114898","url":null,"abstract":"<div><div>The current study explores the trapping of harmful gases using porous organic cage CC1, a covalently bound imine cage with accessible voids. Using WB97XD/6-311G(d, p) theory level, the research computes CC1 and its complexes with pollutants like H2S, SF6, SF4, SOCl2, and SO2. DOS and FMO analyses are performed at DFT/ B3LYP/6-311G(d, p) theoretical level. Interaction energy, NCI, QTAIM, EDD, NBO, charge dissociation, FMO, DOS, and MEP studies provide a detailed insight into the analytes@CC1 complexation. Interaction energies (−4.49 to −0.34 eV) show strong trapping of SOCl2 and SF4 while, slight trapping of H2S within the cavity of CC1. Thermodynamic parameters confirm these findings. Analyses (NCI, QTAIM) indicate strong non-covalent interactions, especially for SOCl2 and SF4. NBO analysis reveals charge transfer from analytes to the cage, except for H2S. EDD analysis is also implemented to verify NBO charge transfer. This study highlights CC1′s peculiar trapping behaviour for the considered analytes.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114898"},"PeriodicalIF":3.0,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evaluate the potential adsorption of graphynes (perfect and doped) for nitrogen mustard gas: A first principles study 评估石墨炔（完全石墨炔和掺杂石墨炔）对氮芥气体的吸附潜力：第一原理研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-03 DOI: 10.1016/j.comptc.2024.114911

Shu Zijing

{"title":"Evaluate the potential adsorption of graphynes (perfect and doped) for nitrogen mustard gas: A first principles study","authors":"Shu Zijing","doi":"10.1016/j.comptc.2024.114911","DOIUrl":"10.1016/j.comptc.2024.114911","url":null,"abstract":"<div><div>Density functional theory (DFT) calculations are used to thoroughly examine the reactivity and electronic sensitivity of pristine and BN-doped graphyne (BNG) toward nitrogen mustard (NM). Graphyne’s electrical conductivity is unaffected by the weak adsorption of NM, which occurs via the Cl atom on the material with an adsorption energy of roughly −3.1 kcal.mol−1. In addition to decreasing graphyne’s reactivity and work function, substituting isoelectronic <img>B<img>N<img> linkages for <img>C<img>C<img> linkages enhances the HOMO-LUMO energy gap (Eg). BNG’s electrical conductivity increases when Eg drops from 2.99 to 1.82 eV due to the adsorption of NM. Additionally, a significant change in BNG’s work function results in a variation in the field electron emission current. Lastly, it is anticipated that the desorption of NM from the BNG surface will take a brief recovery time of roughly 0.05 s at room temperature. It has also been demonstrated that NM concentration affects changes in electrical conductivity. The findings also suggest that BNG could be a promising NM sensor.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114911"},"PeriodicalIF":3.0,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

First-principle study of the effect of Hf doping and VO-Hi co-existence on absorption spectrum, conductivity and carrier activity of β-Ga2O3 掺杂 Hf 和 VO-Hi 共存对 β-Ga2O3 吸收光谱、电导率和载流子活性影响的第一原理研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-02 DOI: 10.1016/j.comptc.2024.114906

Ding-du Chen, Shu-min Wen, Xia Liu, Wei Wang, Er-jun Zhao

{"title":"First-principle study of the effect of Hf doping and VO-Hi co-existence on absorption spectrum, conductivity and carrier activity of β-Ga2O3","authors":"Ding-du Chen, Shu-min Wen, Xia Liu, Wei Wang, Er-jun Zhao","doi":"10.1016/j.comptc.2024.114906","DOIUrl":"10.1016/j.comptc.2024.114906","url":null,"abstract":"<div><div>At present, some progress has been made in the study of Hf doping on the conductivity. However, few studies on the effects of Hf doping, and O vacancy and interstitial H co-existence on photoelectric properties of β-Ga2O3. O vacancy and interstitial H will inevitably exist during the preparation of β-Ga2O3. Given these problems, the effects of Hf doping, O vacancy and interstitial H co-existence on photoelectric properties of β-Ga2O3 were studied using first-principles calculations. Results show that doping and defects affect the photoelectric properties of β-Ga2O3 to some extent. With increased Hf doping concentration, the bandgap of the system decreases gradually, the absorption spectrum in the deep ultraviolet region red shifts, the carrier activity and carrier lifetime are enhanced. The mobility and conductivity of the system also increase with increased doping concentration. The Hf doping and interstitial H can effectively improve the conductivity of the system. In summary, Hf can be used as a powerful candidate material for designing and preparing β-Ga2O3 optoelectronic devices.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114906"},"PeriodicalIF":3.0,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A DFT study of the second-order nonlinear optical properties of [22]smaragdyrin-BF2-NiII porphyrin fused hybrids 关于 [22]smaragdyrin-BF2-NiII卟啉融合杂化物二阶非线性光学特性的 DFT 研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-02 DOI: 10.1016/j.comptc.2024.114907

Ting-Ting Liu , Yan Yan , Yu Yang, Na Hou

{"title":"A DFT study of the second-order nonlinear optical properties of [22]smaragdyrin-BF2-NiII porphyrin fused hybrids","authors":"Ting-Ting Liu , Yan Yan , Yu Yang, Na Hou","doi":"10.1016/j.comptc.2024.114907","DOIUrl":"10.1016/j.comptc.2024.114907","url":null,"abstract":"<div><div>Nonlinear optical response of four [22]smaragdyrin-BF2 (S)-NiII porphyrin (P) fused hybrids were explored by using DFT at CAM-B3LYP/6–31 + G(d)/SDD level of theory. We choose two types of hybrids, S<img>P and P<img>S<img>P fused hybrids, for our study. Calculations indicate that these fused hybrids might be promising candidates for NLO materials based on considerable static and dynamic hyper-Rayleigh scattering (HRS) hyperpolarizability. The P<img>S<img>P fused hybrids possess larger first hyperpolarizabilities values compared to S<img>P hybrids. Further analysis of hyperpolarizability density reveals the nature of the large first hyperpolarizability of the P<img>S<img>P fused hybrids. For all compounds, HRS hyperpolarizability at λ = 1907 nm is higher than the static value. After the interpretation of dipolar and octupolar character of βHRS, these hybrids show the high dipolar character.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114907"},"PeriodicalIF":3.0,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Adsorption of eco-friendly insulating gas C4F7N on PdSe2 monolayer surface: A first-principles study PdSe2 单层表面对环保绝缘气体 C4F7N 的吸附：第一原理研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-02 DOI: 10.1016/j.comptc.2024.114905

Yonggang Xiong , Tao Yao , Fang Xie

{"title":"Adsorption of eco-friendly insulating gas C4F7N on PdSe2 monolayer surface: A first-principles study","authors":"Yonggang Xiong , Tao Yao , Fang Xie","doi":"10.1016/j.comptc.2024.114905","DOIUrl":"10.1016/j.comptc.2024.114905","url":null,"abstract":"<div><div>Heptafluoro-isobutyronitrile (C4F7N) is a novel environmentally friendly insulating and arc extinguishing gas utilized as a replacement for SF6 in gas insulated equipment (GIE). Nevertheless, the potentially hazardous decomposition byproducts of C4F7N resulting from sudden equipment failure may jeopardize the normal operation of GIE and the physical well-being of the operator. In this paper, using the first principles study the adsorption behavior of four common C4F7N decomposition gases (CF4, COF2, CF3CN, C2F5CN) on PdSe2 monolayer, and explore the adsorption mechanism of PdSe2 monolayer on C4F7N decomposition gas. The results show that the PdSe2 monolayer interacts with the four decomposition gases by physical adsorption mechanism, in which the PdSe2 monolayer causes the largest change in electronic properties and maximum work function (0.15 eV) near the Fermi level before and after adsorption of C2F5CN, indicating a strong interaction between C2F5CN and PdSe2 monolayer. The sensitivity of PdSe2 monolayer to C2F5CN was up to 68.61 %. Therefore, PdSe2 monolayer has the potential of selective detection of C2F5CN gas sensing materials, and the findings in this paper provide theoretical guidance for the development of PdSe2 monolayer gas sensing sensors for monitoring C4F7N insulation equipment.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114905"},"PeriodicalIF":3.0,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Exploring the thermal and optical characteristics of Ti3C2 MXene for enhanced photothermal conversion 探索用于增强光热转换的 Ti3C2 MXene 的热学和光学特性

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-10-01 DOI: 10.1016/j.comptc.2024.114903

Hanwen Hu , Wujie Qiu , Jifen Wang

{"title":"Exploring the thermal and optical characteristics of Ti3C2 MXene for enhanced photothermal conversion","authors":"Hanwen Hu , Wujie Qiu , Jifen Wang","doi":"10.1016/j.comptc.2024.114903","DOIUrl":"10.1016/j.comptc.2024.114903","url":null,"abstract":"<div><div>Ti3C2 MXene, a member of the two-dimensional (2D) transition metal carbides family, has garnered significant attention for its exceptional photothermal properties. To understand the mechanistic underpinnings of this feature, we conducted a comprehensive first-principles density functional theory analysis. This study was aimed at investigating the electronic band structure and vibrational characteristics of Ti3C2 MXene to unravel its microscopic process of photothermal conversion. After obtaining its optical and thermal properties, the process by which the material moves from light absorption to heat release is elucidated. The presence of localized surface plasmon resonance (LSPR) effects in Ti3C2 is proved by Finite-difference time-domain (FDTD) simulations. The synergy between the high thermal conductivity network in the Ti layers and the LSPR phenomenon is believed to be responsible for the superior photothermal conversion capabilities. This investigation enhances the understanding of the intrinsic properties of Ti3C2 MXene, confirming its status as an ultrahigh photothermal conversion material.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114903"},"PeriodicalIF":3.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimal donor groups for novel organic dye “3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid” in the context of N‑type dye-sensitized solar cells: A theoretical investigation 新型有机染料 "3-(5-(4-(二苯基氨基)苯乙烯基)噻吩-2-基)-2-氰基丙烯酸 "在 N 型染料敏化太阳能电池中的最佳供体基团：理论研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-09-30 DOI: 10.1016/j.comptc.2024.114901

Preeti Nanda Sahu, Anjali Devi Vasarla, Rajesh Kumar Kumili, Anik Sen

引用次数: 0

DFT study of structural, electronic, magnetic, elastic, and thermoelectric properties of Ta-based half-Heusler alloys CsTaX (X = C, Si, and Ge) for spintronics and thermoelectric technologies 用于自旋电子学和热电技术的 Ta 基半赫斯勒合金 CsTaX（X = C、Si 和 Ge）的结构、电子、磁性、弹性和热电特性的 DFT 研究

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-09-30 DOI: 10.1016/j.comptc.2024.114902

Saba Saleem, Nawaz Muhammad, G. Murtaza, Ahmad Ayyaz, Maha Naeem, Ahmad Usman, Urwa-tul Aysha, Maryam Touqir

{"title":"DFT study of structural, electronic, magnetic, elastic, and thermoelectric properties of Ta-based half-Heusler alloys CsTaX (X = C, Si, and Ge) for spintronics and thermoelectric technologies","authors":"Saba Saleem, Nawaz Muhammad, G. Murtaza, Ahmad Ayyaz, Maha Naeem, Ahmad Usman, Urwa-tul Aysha, Maryam Touqir","doi":"10.1016/j.comptc.2024.114902","DOIUrl":"10.1016/j.comptc.2024.114902","url":null,"abstract":"<div><div>The structural, electronic, elastic, magnetic, and thermoelectric characteristics of three novel Ta-based half-Heusler alloys, CsTaC, CsTaSi, and CsTaGe, have been investigated using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method within the density functional theory (DFT). The volume-optimization graphs show that all compounds are stable in the ferromagnetic (FM) phase. Half-Metallicity of these compounds is confirmed by the density of states (DOS) and band structures. The total magnetic moment for CsTaC is 6 <math><mi>μ</mi></math>B, and for CsTaX (X = Si, Ge) is 2 <math><mi>μ</mi></math>B. The negative pd exchange energy and exchange constants confirm ferromagnetism. The values of Pugh’s ratio (B/G) and Poisson’s ratio (v) reveal that CsTaC is ductile and CsTaX (Si, Ge) is brittle. The thermoelectric response is estimated using the BoltzTraP code, demonstrating that at room temperature, maximum ZT values for CaTaC, CsTaSi, and CsTaGe are 0.99, 0.97, and 0.90, respectively. Consequently, CsTaX (X = C, Si, and Ge) are suitable candidates for spintronic and thermoelectric technologies.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114902"},"PeriodicalIF":3.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Pyrolysis reaction mechanisms of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN) using the ReaxFF force field 利用 ReaxFF 力场分析硝化甘油（NG）和 1,2,4-丁三醇三硝酸酯（BTTN）的热解反应机理

IF 3 3区化学

Computational and Theoretical Chemistry Pub Date : 2024-09-30 DOI: 10.1016/j.comptc.2024.114900

Yong Zhang , Zheng Mei , Ling-Chen Zhou , Jing Ye , Fang-Chao Hou , Bo-Cong Chen , Hao-Long Su , Jing Sun , Liang Song

{"title":"Pyrolysis reaction mechanisms of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN) using the ReaxFF force field","authors":"Yong Zhang , Zheng Mei , Ling-Chen Zhou , Jing Ye , Fang-Chao Hou , Bo-Cong Chen , Hao-Long Su , Jing Sun , Liang Song","doi":"10.1016/j.comptc.2024.114900","DOIUrl":"10.1016/j.comptc.2024.114900","url":null,"abstract":"<div><div>In this study, the ReaxFF-lg reactive force field was verified and employed to simulate the thermal decomposition of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN) at various temperatures (1500–3000 K), elucidating the detailed mechanisms of initial changes, intermediate products, and final product reactions for both energetic materials. The results indicate that the initial reactions of NG and BTTN are similar, and the primary reactions involve the cleavage of the O-NO2 bond and the dissociation of the C<img>C bond. At 1500 K, the breakage of O-NO2 bonds becomes the dominant reaction. As the temperature increases, in addition to the removal of NO2, the breakage of C<img>C chains is observed above 2000 K. The formation of intermediates NO2, HNO2, NO, and CH2O accelerates the chemical reaction. The proportions of CO2 and H2O in the final products of BTTN change significantly with temperature.</div></div>","PeriodicalId":284,"journal":{"name":"Computational and Theoretical Chemistry","volume":"1241 ","pages":"Article 114900"},"PeriodicalIF":3.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0