107 results on '"Guangwu Li"'
Search Results
2. Exploring the mechanism of olfactory recognition in the initial stage by modeling the emission spectrum of electron transfer.
- Author
-
Shu Liu, Rao Fu, and Guangwu Li
- Subjects
Medicine ,Science - Abstract
Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang-Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.
- Published
- 2020
- Full Text
- View/download PDF
3. Data on the detail information of influence of substrate temperature on the film morphology and photovoltaic performance of non-fullerene organic solar cells
- Author
-
Jicheng Zhang, SuFei Xie, Zhen Lu, Yang Wu, Hongmei Xiao, Xuejuan Zhang, Guangwu Li, Cuihong Li, Xuebo Chen, Wei Ma, and Zhishan Bo
- Subjects
Computer applications to medicine. Medical informatics ,R858-859.7 ,Science (General) ,Q1-390 - Abstract
This data contains additional data related to the article “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” (Jicheng Zhang et al., In press) [1]. Data include measurement and characterization instruments and condition, detail condition to fabricate norfullerene solar cell devices, hole-only and electron-only devices. Detail condition about how to control the film morphology of devices via tuning the temperature of substrates was also displayed. More information and more convincing data about the change of film morphology for active layers fabricated from different temperature, which is attached to the research article of “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” was given.
- Published
- 2017
- Full Text
- View/download PDF
4. Angularly fused diaza-dinaphthopyrenes: regio-selective synthesis, crystal structures and isomer-dependent mechanochromic fluorescent properties
- Author
-
Yan Kou, Guangwu Li, Yi Han, Mengwei Li, Tingting Wang, Zhiyu Qu, and Yulan Chen
- Subjects
General Chemistry - Abstract
A one-pot synthesis of the first angularly fused diaza-dinaphthopyrene isomers with central and axial symmetry is reported. They showed isomer-specific crystal structures, tunable optical and redox properties, and turn-on mechanochromic fluorescence.
- Published
- 2023
5. A graphyne spoked wheel
- Author
-
Boyi Zhang, Shaofei Wu, Xudong Hou, Guangwu Li, Yong Ni, Qiuyu Zhang, Jun Zhu, Yi Han, Peng Wang, Zhe Sun, and Jishan Wu
- Subjects
General Chemical Engineering ,Biochemistry (medical) ,Materials Chemistry ,Environmental Chemistry ,General Chemistry ,Biochemistry - Published
- 2022
6. Exploring Electronic Characteristics of Acceptor–Donor–Acceptor‐Type Molecules by Single‐Molecule Charge Transport
- Author
-
Peihui Li, Wan Xiong, Jinying Wang, Jie Hao, Mingpeng Li, Boyu Wang, Yijian Chen, Wei Si, Haiyang Ren, Guangwu Li, Yongsheng Chen, Jingtao Lü, Hongtao Zhang, Chuancheng Jia, and Xuefeng Guo
- Subjects
Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Published
- 2023
7. Identification of T2W hypointense ring as a novel noninvasive indicator for glioma grade and IDH genotype
- Author
-
Yawen Lu, Ningfang Du, Xuhao Fang, Weiquan Shu, Wei Liu, Xinxin Xu, Yao Ye, Li Xiao, Renling Mao, Kefeng Li, Guangwu Lin, and Shihong Li
- Subjects
Glioma ,Magnetic resonance imaging ,Isocitrate dehydrogenase ,T2W hypointense ring ,T2-FLAIR mismatch ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background This study aimed to evaluate the T2W hypointense ring and T2-FLAIR mismatch signs in gliomas and use these signs to construct prediction models for glioma grading and isocitrate dehydrogenase (IDH) mutation status. Methods Two independent radiologists retrospectively evaluated 207 glioma patients to assess the presence of T2W hypointense ring and T2-FLAIR mismatch signs. The inter-rater reliability was calculated using the Cohen’s kappa statistic. Two logistic regression models were constructed to differentiate glioma grade and predict IDH genotype noninvasively, respectively. Receiver operating characteristic (ROC) analysis was used to evaluate the developed models. Results Of the 207 patients enrolled (119 males and 88 females, mean age 51.6 ± 14.8 years), 45 cases were low-grade gliomas (LGGs), 162 were high-grade gliomas (HGGs), 55 patients had IDH mutations, and 116 were IDH wild-type. The number of T2W hypointense ring signs was higher in HGGs compared to LGGs (p
- Published
- 2024
- Full Text
- View/download PDF
8. Synthesis and Structural Elucidation of Bisdibenzocorannulene in Multiple Redox States
- Author
-
Chenxin Yang, Sheng Xie, Wangwang Peng, Huiping Xiao, Bo Li, Xinhao Wang, Jishan Wu, Shenglian Luo, Guangwu Li, and Zebing Zeng
- Subjects
Steric effects ,Diradical ,Chemistry ,General Medicine ,General Chemistry ,Photochemistry ,Redox ,Catalysis ,Dication ,Metal ,Delocalized electron ,visual_art ,visual_art.visual_art_medium ,Singlet state ,Antiaromaticity - Abstract
We report an anti-folded bowl-shaped bisdibenzocorannulene (BDBC) featuring a new chair-cyclohexane-like hexagon as a bridge of two dibenzocorannulene moieties. The neutral compound showed multiple redox-active properties and could be converted to the corresponding redox states through chemical reduction or oxidation. Chemical reduction of BDBC by stoichiometric addition of metallic potassium in the presence of [18]crown-6 ether, provided a radical anion BDBC.- and a dianion BDBC2- , respectively; while chemical oxidation by silver hexafluoroantimonate(V), converted the neutral compound to an open-shell singlet diradical dication (BDBC.. )2+ . The structural consequences of both electron-reduction and oxidation were closely related to the release of ring-strain of the bowl-shaped π-scaffold and imposed steric hindrance of the hexagonal bridge. In addition, the unusual open-shell nature of the dication could mainly be attributed to the changing of localized antiaromaticity in the closed-shell structure to delocalized character in the biradical, and thus the emergence of weakly bonded π-electrons.
- Published
- 2021
9. Machine Vision Automated Chiral Molecule Detection and Classification in Molecular Imaging
- Author
-
Haitao Yang, Mykola Telychko, Jiong Lu, Shaotang Song, Xiaonan Wang, Jiali Li, Guangwu Li, Jishan Wu, Jun Yin, Jing Li, and Yixin Zhu
- Subjects
Chemistry ,business.industry ,Machine vision ,Deep learning ,Supramolecular chemistry ,Pattern recognition ,General Chemistry ,Biochemistry ,Catalysis ,Characterization (materials science) ,Range (mathematics) ,Scanning probe microscopy ,Colloid and Surface Chemistry ,Artificial intelligence ,Molecular imaging ,Chirality (chemistry) ,business - Abstract
Scanning probe microscopy (SPM) is recognized as an essential characterization tool in a broad range of applications, allowing for real-space atomic imaging of solid surfaces, nanomaterials, and molecular systems. Recently, the imaging of chiral molecular nanostructures via SPM has become a matter of increased scientific and technological interest due to their imminent use as functional platforms in a wide scope of applications, including nonlinear chiroptics, enantioselective catalysis, and enantiospecific sensing. Due to the time-consuming and error-prone image analysis process, a highly efficient analytic framework capable of identifying complex chiral patterns in SPM images is needed. Here, we adopted a state-of-the-art machine vision algorithm to develop a one-image-one-system deep learning framework for the analysis of SPM images. To demonstrate its accuracy and versatility, we employed it to determine the chirality of the molecules comprising two supramolecular self-assemblies with two distinct chiral organization patterns. Our framework accurately detected the position and labeled the chirality of each molecule. This framework underpins the tremendous potential of machine learning algorithms for the automated recognition of complex SPM image patterns in a wide range of research disciplines.
- Published
- 2021
10. Highly Strained 1,8-Naphthalene-Bridged Cyclic Oligophenylenes and Their Open-Shell Diradical Dications
- Author
-
Guangwu Li, Xuefeng Lu, Jishan Wu, Chunchen Liu, Ya Zou, and Hoa Phan
- Subjects
010405 organic chemistry ,Chemistry ,Band gap ,Diradical ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Crystallography ,chemistry.chemical_compound ,Phenylene ,Molecule ,Singlet state ,Physical and Theoretical Chemistry ,Open shell ,Naphthalene - Abstract
The synthesis and characterization of two 1,8-naphthalene-bridged cyclic oligo-para-phenylenes with four or eight phenylene units are reported. Both molecules exhibit a highly strained structure with two nearly face-to-face arranged p,p'-biphenylylene/p,p'-quaterphenylylene chains. Their dications were obtained by chemical oxidation with NO·SbF6, and both showed open-shell singlet diradical character with a small singlet-triplet energy gap.
- Published
- 2021
11. Facile Synthesis of Aryl-Substituted Cycloarenes via Bismuth(III) Triflate-Catalyzed Cyclization of Vinyl Ethers
- Author
-
Yi Han, Guangwu Li, Wei Fan, Shaoqiang Dong, Jishan Wu, and Xuefeng Lu
- Subjects
chemistry.chemical_classification ,Aryl ,chemistry.chemical_element ,Polycyclic aromatic hydrocarbon ,Aromaticity ,General Chemistry ,Electronic structure ,Combinatorial chemistry ,Bismuth ,Catalysis ,chemistry.chemical_compound ,chemistry ,Kekulene ,Trifluoromethanesulfonate - Abstract
Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure, but their synthesis is very challenging. Herein, we report a facile synthetic strategy prima...
- Published
- 2021
12. Fused Quinoidal Dithiophene‐Based Helicenes: Synthesis by Intramolecular Radical–Radical Coupling Reactions and Dynamics of Interconversion of Enantiomers
- Author
-
Guangwu Li, Shaofei Wu, Ya Zou, Jishan Wu, Qing Jiang, Taisuke Matsuno, Yi Han, and Hiroyuki Isobe
- Subjects
Computational chemistry ,Chemistry ,Intramolecular force ,Molecule ,Dehydrogenation ,Density functional theory ,General Chemistry ,Electronic structure ,General Medicine ,Enantiomer ,Racemization ,Catalysis ,Coupling reaction - Abstract
A series of fused quinoidal dithiophene-based double and triple helicenes (1-M, 2-M, 2-M-Cl, 3-M, 3-M-Cl) were synthesized by intramolecular radical-radical coupling followed by oxidative dehydrogenation reaction. These helical molecules show dynamic interconversion of enantiomers in solution as revealed by variable-temperature NMR measurements, and the energy barriers are correlated to the substituents and topological structures. Notably, dynamic high performance liquid chromatography was used to quantitatively investigate the room-temperature racemization process between the (P,P,M)- and (P,M,M)- enantiomers of the triple helical 3-M-Cl, which gave an interconversion energy barrier in consistent with density functional theory calculations. Their optical and electrochemical properties are dependent on the fusion mode. Our studies provide both new synthetic strategy and new dynamic analytical method for helicenes with unique electronic structure.
- Published
- 2021
13. Facile Synthesis of Nitrogen-Doped [(6.)m8]nCyclacene Carbon Nanobelts by a One-Pot Self-Condensation Reaction
- Author
-
Guangwu Li, Jishan Wu, Yong Ni, Yi Han, and Jun Zhu
- Subjects
Absorption spectroscopy ,Chemistry ,chemistry.chemical_element ,General Chemistry ,Self-condensation ,Conjugated system ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Crystallography ,Colloid and Surface Chemistry ,Electromagnetic shielding ,Molecule ,Molecular orbital ,Carbon - Abstract
Synthesis of fully conjugated carbon nanobelts (CNBs) remains one of the biggest challenges in organic chemistry. Herein, we report a facile synthesis of four nitrogen-doped [(6.)m8]ncyclacene CNBs (m = 1-3; n = 3,4) with different sizes by a one-pot self-condensation reaction of three bis(o-aminobenzophenone) precursors. The belt-shaped structure was confirmed by X-ray crystallographic analysis. The existence of eight-membered [1,5]diazocine rings releases the strain while maintaining weak π-conjugation throughout the belt backbone, which is supported by electronic absorption spectra and frontier molecular orbital analysis. NMR measurements and magnetic shielding calculations suggest an alternating aromatic-nonaromatic ring structure, with a slightly more shielded chemical environment in the cavity. Our method opens the opportunities to access more sophisticated π-conjugated 2D/3D belt-/cage-like molecules in a simple way.
- Published
- 2021
14. On-surface synthesis of graphene nanostructures with π-magnetism
- Author
-
Jie Su, Guangwu Li, Ying Li, Jishan Wu, Jiong Lu, Mykola Telychko, Jing Li, Shaotang Song, and Chenliang Su
- Subjects
Spintronics ,Graphene ,Magnetism ,Nanotechnology ,General Chemistry ,law.invention ,Characterization (materials science) ,Quantum technology ,chemistry.chemical_compound ,Scanning probe microscopy ,chemistry ,law ,Organic synthesis ,Graphene nanoribbons - Abstract
Graphene nanostructures (GNs) including graphene nanoribbons and nanoflakes have attracted tremendous interest in the field of chemistry and materials science due to their fascinating electronic, optical and magnetic properties. Among them, zigzag-edged GNs (ZGNs) with precisely-tunable π-magnetism hold great potential for applications in spintronics and quantum devices. To improve the stability and processability of ZGNs, substitutional groups are often introduced to protect the reactive edges in organic synthesis, which renders the study of their intrinsic properties difficult. In contrast to the conventional wet-chemistry method, on-surface bottom-up synthesis presents a promising approach for the fabrication of both unsubstituted ZGNs and functionalized ZGNs with atomic precision via surface-catalyzed transformation of rationally-designed precursors. The structural and spin-polarized electronic properties of these ZGNs can then be characterized with sub-molecular resolution by means of scanning probe microscopy techniques. This review aims to highlight recent advances in the on-surface synthesis and characterization of a diversity of ZGNs with π-magnetism. We also discuss the important role of precursor design and reaction stimuli in the on-surface synthesis of ZGNs and their π-magnetism origin. Finally, we will highlight the existing challenges and future perspective surrounding the synthesis of novel open-shell ZGNs towards next-generation quantum technology.
- Published
- 2021
15. Tailoring long-range superlattice chirality in molecular self-assemblies via weak fluorine-mediated interactions
- Author
-
Lulu Wang, Jishan Wu, Jiong Lu, Guangwu Li, Xinnan Peng, Shaotang Song, Chia-Hsiu Hsu, Ming Wah Wong, Feng-Chuan Chuang, Mykola Telychko, and Jie Su
- Subjects
Materials science ,Intermolecular force ,technology, industry, and agriculture ,Supramolecular chemistry ,General Physics and Astronomy ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Chemical physics ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,Scanning tunneling microscope ,Chirality (chemistry) ,Hexaphenylbenzene ,Lone pair - Abstract
Controllable fabrication of enantiospecific molecular superlattices is a matter of imminent scientific and technological interest. Herein, we demonstrate that long-range superlattice chirality in molecular self-assemblies can be tailored by tuning the interplay of weak intermolecular non-covalent interactions between hexaphenylbenzene-based enantiomers. By means of high-resolution scanning tunneling microscopy measurements, we demonstrate that the functionalization of a hexaphenylbenzene-based molecule with fluorine (F) atoms leads to the formation of molecular self-assemblies with distinct long-range chiral recognition patterns. We employed density functional theory calculations to quantify F-mediated lone pair F⋯π, C–H⋯F, and F⋯F interactions attributed to the distinct enantiospecific molecular self-organizations. Our findings underpin a viable route to fabricate long-range chiral recognition patterns in supramolecular assemblies by engineering the weak non-covalent intermolecular interactions.
- Published
- 2021
16. Development, application, and evaluation of a problem-based learning method in clinical laboratory education
- Author
-
Xu Chen, Xiaoqiang Li, Xiandong Li, Chunyan Peng, Jun Lv, Fei Xie, and Guangwu Li
- Subjects
0301 basic medicine ,China ,Students, Medical ,Teaching method ,education ,Clinical Biochemistry ,Medical laboratory ,Biochemistry ,03 medical and health sciences ,0302 clinical medicine ,Laboratory education ,Surveys and Questionnaires ,Humans ,Curriculum ,Structure (mathematical logic) ,Medical education ,business.industry ,Biochemistry (medical) ,Problem-Based Learning ,General Medicine ,Test (assessment) ,030104 developmental biology ,Problem-based learning ,030220 oncology & carcinogenesis ,Laboratories ,business ,Psychology ,Working environment - Abstract
Background There is a big gap between theory and real clinical practice with respect to the structure of clinical laboratory medicine (CLM) education in China. An integrated teaching method is urgently required, to improve student competency and prepare students to deal with complex challenges in the working environment. Methods A total of 122 fourth-year CLM students studying at Hubei University between 2018 and 2019 were randomly assigned to a traditional teaching methods group or a problem-based learning (PBL) group. In the PBL group students were instructed to exchange their thoughts, identify information gaps, rehearse and perform simulated clinical scenarios, and incorporate the new information into cases in small groups. Theory tests, questionnaires, and clinical performance assessments were used to evaluate the effectiveness of PBL and compare it with that of traditional teaching methods. Results PBL resulted in significantly better theory test scores, better student feedback scores, and clinical performance assessments, and a higher rate of satisfaction among students and teachers. Conclusion PBL is an effective way to help CLM students develop comprehensive abilities to deal with real clinical laboratory work. It is a promising education method and should be generalized to all subtypes of clinical laboratory curriculums in the future.
- Published
- 2020
17. Extended para-Quinodimethanes and Quinones
- Author
-
Guangwu Li and Jishan Wu
- Published
- 2022
18. Real-Space Imaging of a Single-Molecule Monoradical Reaction
- Author
-
Pin Lyu, Xinzhe Li, Jishan Wu, Hanyan Fang, Jie Su, Ying Li, Jiong Lu, Mykola Telychko, Chenliang Su, Chun Zhang, Zhizhan Qiu, Hiromitsu Maeda, Jing Li, Na Guo, Ming Joo Koh, Xinnan Peng, Yohei Haketa, Xinbang Wu, Shaotang Song, and Guangwu Li
- Subjects
Coupling ,Chemistry ,Radical ,General Chemistry ,010402 general chemistry ,Space (mathematics) ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Chemical instability ,Coherence length ,Colloid and Surface Chemistry ,Chemical physics ,Molecule ,Condensed Matter::Strongly Correlated Electrons ,Spin (physics) ,Hyperfine structure - Abstract
Organic radicals consisting of light elements exhibit a low spin-orbit coupling and weak hyperfine interactions with a long spin coherence length, which are crucial for future applications in molecular spintronics. However, the synthesis and characterization of these organic radicals have been a formidable challenge due to their chemical instability arising from unpaired electrons. Here, we report a direct imaging of the surface chemical transformation of an organic monoradical synthesized via the monodehydrogenation of a chemically designed precursor. Bond-resolved scanning tunneling microscopy unambiguously resolves various products formed through a complex structural dissociation and rearrangement of organic monoradicals. Density functional theory calculations reveal detailed reaction pathways from the monoradical to different cyclized products. Our study provides unprecedented insights into complex surface reaction mechanisms of organic radical reactions at the single molecule level, which may guide the design of stable organic radicals for future quantum technology applications.
- Published
- 2020
19. Perylene‐Fused, Aggregation‐Free Polycyclic Aromatic Hydrocarbons for Solution‐Processed Distributed Feedback Lasers
- Author
-
María A. Díaz-García, Juan Casado, Guangwu Li, Ya Zou, José M. Villalvilla, José A. Quintana, Pedro G. Boj, Shaofei Wu, Víctor Bonal, Sergio Moles Quintero, Qing Jiang, Yong Ni, Jishan Wu, Universidad de Alicante. Departamento de Física Aplicada, Universidad de Alicante. Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante. Instituto Universitario de Materiales, and Física de la Materia Condensada
- Subjects
Física de la Materia Condensada ,010405 organic chemistry ,Library science ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Polycyclic aromatic hydrocarbons ,Catalysis ,0104 chemical sciences ,Solution processed ,chemistry.chemical_compound ,Scholarship ,chemistry ,Física Aplicada ,Tier 2 network ,Political science ,Organic lasers ,Amplified spontaneous emission ,Perylene ,Dyes ,Óptica - Abstract
Perylene‐fused, aggregation‐free polycyclic aromatic hydrocarbons with partial zigzag periphery (ZY‐01, ZY‐02, and ZY‐03) were synthesized. X‐ray crystallographic analysis reveals that there is no intermolecular π–π stacking in any of the three molecules, and as a result, they show moderate‐to‐high photoluminescence quantum yield in both solution and in the solid state. They also display the characteristic absorption and emission spectra of perylene dyes. ZY‐01 and ZY‐02 with a nearly planar π‐conjugated skeleton exhibit amplified spontaneous emission (ASE) when dispersed in polystyrene thin films. Solution‐processed distributed feedback lasers have been fabricated using ZY‐01 and ZY‐02 as active gain materials, both showing narrow emission linewidth (
- Published
- 2020
20. Benzidine/Quinoidal‐Benzidine‐Linked, Superbenzene‐Based π‐Conjugated Chiral Macrocycles and Cyclophanes
- Author
-
Guangwu Li, Shaofei Wu, Yi Han, Hiroyuki Isobe, Qing Jiang, Hoa Phan, Ya Zou, Taisuke Matsuno, and Jishan Wu
- Subjects
010405 organic chemistry ,Chemistry ,General Chemistry ,General Medicine ,Conjugated system ,010402 general chemistry ,01 natural sciences ,Catalysis ,Coupling reaction ,Benzidine ,0104 chemical sciences ,chemistry.chemical_compound ,Polymer chemistry ,Dehydrogenation ,Cyclic voltammetry ,Enantiomer ,Host–guest chemistry ,Cyclophane - Abstract
Synthesis of fully conjugated cyclophanes containing large-size polycyclic aromatics is challenging. Now, three benzidine-linked, hexa-peri-hexabenzocoronene (superbenzene)-based ortho-, para-, and meta-cyclophanes are synthesized through intermolecular Yamamoto coupling reaction of structurally pre-organized precursors. Subsequent oxidative dehydrogenation gave the corresponding quinoidal benzidine-linked cyclophanes. Their geometries were confirmed by X-ray crystallographic analysis and their electronic properties were investigated by electronic absorption, cyclic voltammetry, and DFT calculations. The quinoidal benzidine-linked cyclophanes show thermally populated paramagnetic activity with a relatively large singlet-triplet energy gap. Two enantiomers for the ortho-cyclophanes (1-NH and 1-N) were isolated and their chiral figure-of-eight macrocyclic structures were identified. The cage-like cyclophanes 2-NH and 3-NH with concave surface can selectively encapsulate fullerene C70 .
- Published
- 2020
21. Formation of Azulene‐Embedded Nanographene: Naphthalene to Azulene Rearrangement During the Scholl Reaction
- Author
-
Yi Han, Chunyan Chi, Zibo Xue, Yanwei Gu, Shaoqiang Dong, Yong Ni, and Guangwu Li
- Subjects
Reaction mechanism ,010405 organic chemistry ,Chemistry ,General Medicine ,Electronic structure ,General Chemistry ,Azulene ,Ring (chemistry) ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Scholl reaction ,chemistry.chemical_compound ,Helicene ,Arenium ion ,Rearrangement reaction ,Naphthalene - Abstract
Incorporation of a non-hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene-bridged double [6]helicene and heptagon-containing nanographene by the Scholl reaction, an unexpected azulene-embedded nanographene and its triflyloxylated product were obtained, as confirmed by X-ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring-fused substructure containing two formal azulene units is formed, but only one of them shows an azulene-like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2-phenyl migration and a naphthalene to azulene rearrangement reaction according to an in-silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene-based molecular materials.
- Published
- 2020
22. Tailoring long-range superlattice chirality in molecular self-assemblies
- Author
-
Mykola, Telychko, Lulu, Wang, Chia-Hsiu, Hsu, Guangwu, Li, Xinnan, Peng, Shaotang, Song, Jie, Su, Feng-Chuan, Chuang, Jishan, Wu, Ming Wah, Wong, and Jiong, Lu
- Abstract
Controllable fabrication of enantiospecific molecular superlattices is a matter of imminent scientific and technological interest. Herein, we demonstrate that long-range superlattice chirality in molecular self-assemblies can be tailored by tuning the interplay of weak intermolecular non-covalent interactions between hexaphenylbenzene-based enantiomers. By means of high-resolution scanning tunneling microscopy measurements, we demonstrate that the functionalization of a hexaphenylbenzene-based molecule with fluorine (F) atoms leads to the formation of molecular self-assemblies with distinct long-range chiral recognition patterns. We employed density functional theory calculations to quantify F-mediated lone pair F⋯π, C-H⋯F, and F⋯F interactions attributed to the distinct enantiospecific molecular self-organizations. Our findings underpin a viable route to fabricate long-range chiral recognition patterns in supramolecular assemblies by engineering the weak non-covalent intermolecular interactions.
- Published
- 2021
23. Potassium Titanate Supported Atomically Dispersed Palladium for Catalytic Oxidation
- Author
-
Li Zhou, Shuren He, Xiaohong Xu, Guangwu Li, and Chuancheng Jia
- Subjects
General Chemical Engineering ,General Engineering ,General Physics and Astronomy ,Medicine (miscellaneous) ,General Materials Science ,Biochemistry, Genetics and Molecular Biology (miscellaneous) - Abstract
Single-atom catalysts based on noble metals provide efficient atomic utilization along with enhanced reactivity. Herein, a convenient strategy to construct atomically dispersed palladium catalyst on layered potassium titanate (KTO), which has enhanced interaction between the TiO
- Published
- 2022
24. Tailoring Long-Range Superlattice Chirality in the Molecular Selfassemblies via Weak Fluorine-Mediated Interactions
- Author
-
Mykola Telychko, Lulu Wang, Chia-Hsiu Hsu, Guangwu Li, Xinnan Peng, Shaotang Song, Jie Su, Feng-Chuan Chuang, Jishan Wu, Richard Ming Wah Wong, and Jiong Lu
- Abstract
Controllable fabrication of the enantiospecific molecular superlattices is a matter of imminent scientific and technological interest. Herein, we demonstrate that long-range superlattice chirality in molecular self-assemblies can be tailored by tuning the interplay of weak intermolecular non-covalent interactions. Different chiral recognition patterns are achieved in the two molecular self-assemblies comprised by two molecular enantiomers with identical steric conformations, derived from the hexaphenylbenzene – the smallest star-shaped polyphenylene. By means of high-resolution scanning tunneling microscopy measurements, we demonstrate that functionalization of star-shaped polyphenylene with fluorine (F) atoms leads to the formation of molecular self-assemblies with the distinct long-range chiral recognition patterns. We employed the density functional theory calculations to quantify F-mediated lone pair F ···π, C-H··· F, F···F interactions attributed to the tunable enantiospecific molecular self-organizations. Our findings underpin a viable route to tailor long-range chiral recognition patterns in supramolecular assemblies by engineering the weak non-covalent intermolecular interactions.
- Published
- 2021
25. Global Aromaticity in Macrocyclic Polyradicaloids: Hückel’s Rule or Baird’s Rule?
- Author
-
Chunchen Liu, Yong Ni, Jishan Wu, Guangwu Li, and Xuefeng Lu
- Subjects
Physics ,Valence (chemistry) ,Chemical physics ,Diradical ,Excited state ,Hückel's rule ,Aromaticity ,General Medicine ,General Chemistry ,Annulene ,Ground state ,Antiaromaticity - Abstract
Aromaticity is one of the most important concepts in organic chemistry to understand the electronic properties of cyclic π-conjugated molecules. Over a century, different aromaticity rules have been developed and validated. For planar monocyclic conjugated polyenes (also known as [n]annulenes), they will be aromatic if they contain [4N + 2] π electrons according to Huckel's rule, or antiaromatic if they have [4N] π electrons. Topological change from a planar to a half-twisted Mobius strip will lead to [4N] ([4N + 2]) aromaticity (antiaromaticity), which is just inverse to Huckel's rule. When the molecules are excited into the first triplet excited state, the Huckel (anti)aromaticity observed in the ground state will become reversed according to Baird's rule. Strictly speaking, these basic rules are only applicable for monocyclic conjugated systems, but some polycyclic systems such as porphyrinoids may also follow these rules if there is a dominant [n]annulene-like conjugation pathway. On the other hand, all-benzenoid polycyclic aromatic hydrocarbons usually display local aromaticity with π electrons predominantly localized at certain benzene rings according to Clar's aromatic sextet rule. In recent years, some proaromatic and antiaromatic molecules with even number of paired electrons have been found to exhibit open-shell diradical character and unique optical, electronic, and magnetic activities. One of the major driving forces is their intrinsic tendency to become aromatic in the open-shell diradical/polyradical forms. A number of stable diradicaloids and linear polyradicaloids have been successfully synthesized by using thermodynamic and kinetic stabilizing strategies. Herein, our particular interest is a type of macrocyclic polyradicaloid in which multiple frontier π-electrons are antiferromagnetically coupled with each other in a cyclic mode. Formally, these free electrons may behave like normal π-electrons in the [n]annulenes, and thus, it raises questions about their possible global aromaticity and which rule they will follow. In the past 5 years, our group has synthesized a series of macrocyclic polyradicaloids and systematically investigated their global aromaticity and electronic properties. Some important findings include: (1) global (anti)aromaticity is generally observed, but there is a balance between local aromaticity and global aromaticity; (2) most of these molecules follow Huckel's rule in the singlet state and display respective (anti)aromatic characteristics; (3) in some special cases, both Huckel's rule and Baird's rule can be applicable, and a unique annulene-within-an-annulene super-ring structure was demonstrated for the first time; (4) global antiaromaticity in the transition state is also important and a slow valence tautomerization process was observed in a supercyclobutadiene tetraradicaloid. These studies demonstrate how these open-shell macrocyclic polyradicaloids adapt their geometry and spin state to reach the lowest-energy state (aromatic). In this Account, we will mainly discuss their synthesis, global aromaticity, and the fundamental structure-radical character-aromaticity-properties relationships. Various experimental methods (e.g., NMR, X-ray crystallographic analysis, and electronic absorption spectroscopy) and theoretical calculations (e.g., anisotropy of the induced current density, nucleus independent chemical shift, and isochemical shielding surface) have been used to elaborate their (anti)aromatic character. At the end, a perspective on the possible three-dimensional global aromaticity in fully conjugated cagelike diradicaloids or polyradicaloids will be also discussed.
- Published
- 2019
26. Using ternary blend as a strategy to improve the driving force for charge transfer and facilitate electron transport in polymer solar cells
- Author
-
Shiyu Feng, Xinjun Xu, Zhaozhao Bi, Guangwu Li, Zhishan Bo, Miao Li, Wei Ma, Xue Gong, and Heng Lu
- Subjects
Materials science ,Fullerene ,Energy conversion efficiency ,Charge (physics) ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Acceptor ,Electron transport chain ,Polymer solar cell ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Chemical engineering ,Materials Chemistry ,Electrical and Electronic Engineering ,0210 nano-technology ,Ternary operation ,Voltage - Abstract
The recently emerged non-fullerene small molecular acceptors can enhance the light absorption and increase the open-circuit voltage in polymer solar cells (PSCs); however, sometimes a decrease in the driving force for charge transfer from donor to acceptor is accompanied. Here, we reported a ternary blend strategy by utilizing fullerene derivative (PC71BM) as a third component to improve the driving force for charge transfer, the charge transport, and the film morphology. Accordingly, the ternary blend PSCs demonstrate a much enhanced power conversion efficiency (PCE) with an optimized value of 9.18% and a good fill factor (FF) of 63%. In comparison, the non-fullerene PSCs without the third component only show a PCE of 6.90% and an FF value of 56%.
- Published
- 2019
27. One step to perylene monoimides and derived alkynyl bridged photovoltaic acceptors
- Author
-
Yurong Jiang, Tullimilli Y. Gopalakrishna, Heng Ma, Deen Guo, Ruiping Qin, Guangwu Li, and Jien Yang
- Subjects
chemistry.chemical_classification ,Materials science ,Band gap ,Process Chemistry and Technology ,General Chemical Engineering ,Energy conversion efficiency ,Wide-bandgap semiconductor ,02 engineering and technology ,Polymer ,Electron acceptor ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Molecule ,0210 nano-technology ,HOMO/LUMO ,Perylene - Abstract
Here, this study presents a simply synthesis proposal for perylene monoimides with traditional wet solution reaction in one step from commercially available perylene dianhydride and the moderate yield has been got. Their dimmer or ethynylene or butadiynylene bridged perylene derivatives were then developed. The work expanded the structural diversity of these dye molecules to a multifunctional class of n-type semiconductor materials. The high LUMO level (−3.83∼-3.96 eV) reduced the energy loss by associating wide bandgap polymer refer to PC71BM (−4.04 eV). Using these compounds as non-fullerene electron acceptors constructs the inverted solar cells, the power conversion efficiency is up to 1.45% for wide band gap polymer donor with an ultrathin active layer thickness of 30 nm.
- Published
- 2019
28. Perylene Monoimide Dimers Enhance Ternary Organic Solar Cells Efficiency by Induced D–A Crystallinity
- Author
-
Miao Li, Jishan Wu, Deen Guo, Ruiping Qin, Guangwu Li, and Zhishan Bo
- Subjects
Organic solar cell ,Component (thermodynamics) ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Acceptor ,0104 chemical sciences ,Molecular aggregation ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,0210 nano-technology ,Ternary operation ,Perylene - Abstract
Three acetylene-bridged perylene monoimide dimers were used as the second nonfullerene acceptor component for efficient ternary solar cells. The molecular aggregation behavior of the host donor and...
- Published
- 2018
29. Diazuleno‐ s ‐indacene Diradicaloids: Syntheses, Properties, and Local (anti)Aromaticity Shift from Neutral to Dicationic State
- Author
-
Qing Jiang, Tao Tao, Hoa Phan, Yi Han, Tullimilli Y. Gopalakrishna, Tun Seng Herng, Guangwu Li, Liu Yuan, Jun Ding, and Chunyan Chi
- Subjects
010405 organic chemistry ,General Medicine ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences - Published
- 2018
30. Diazuleno‐ s ‐indacene Diradicaloids: Syntheses, Properties, and Local (anti)Aromaticity Shift from Neutral to Dicationic State
- Author
-
Chunyan Chi, Tun Seng Herng, Tao Tao, Liu Yuan, Tullimilli Y. Gopalakrishna, Jun Ding, Guangwu Li, Qing Jiang, Yi Han, and Hoa Phan
- Subjects
010405 organic chemistry ,Diradical ,Chemistry ,Radical ,Aromaticity ,General Chemistry ,Azulene ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,Catalysis ,0104 chemical sciences ,NMR spectra database ,Crystallography ,chemistry.chemical_compound ,Moiety ,Polycyclic Hydrocarbons - Abstract
Non-alternant, non-benzenoid π-conjugated polycyclic hydrocarbons (PHs) are expected to exhibit very different electronic properties from all-benzenoid PHs. Reported herein are the syntheses and physical properties of four derivatives of two azulene-fused s-indacene isomers, the diazuleno[2,1-a:2',1'-g]-s-indacene (DAI-1) and diazuleno[2,1-a:1',2'-h]-s-indacene (DAI-2). The backbone of both isomers contains 28π electrons and is a 7-5-5-6-5-5-7 fused ring system. X-ray crystallographic analysis, NMR spectra, and theoretical calculations (ACID, NICS) reveal a structure with two aromatic azulene units fused with a central anti-aromatic s-indacene moiety. All compounds exhibit open-shell diradical character and are magnetically active, but the derivatives of DAI-2 show larger radical character than the respective ones of DAI-1. Their dications were isolated in crystalline form and all experimental and theoretical analyses disclose a shift of local (anti)aromaticity along the backbone, with two aromatic tropylium rings at the termini.
- Published
- 2018
31. Facile Synthesis of Nitrogen-Doped [(6.)
- Author
-
Jun, Zhu, Yi, Han, Yong, Ni, Guangwu, Li, and Jishan, Wu
- Abstract
Synthesis of fully conjugated carbon nanobelts (CNBs) remains one of the biggest challenges in organic chemistry. Herein, we report a facile synthesis of four nitrogen-doped [(6.)
- Published
- 2021
32. Ultrahigh-yield on-surface synthesis and assembly of circumcoronene into a chiral electronic Kagome-honeycomb lattice
- Author
-
Xinnan Peng, Shaotang Song, Mykola Telychko, Guangwu Li, Pavel Jelínek, Diego Soler-Polo, Jie Su, Pingo Mutombo, Jishan Wu, Jiong Lu, Ming Joo Koh, Mark T. Edmonds, and UAM. Departamento de Física Teórica de la Materia Condensada
- Subjects
Materials science ,Nanographenes ,Tight-Binding Calculations ,Superlattice ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,High Yield ,Scanning probe microscopy ,Honeycomb ,Molecule ,Topology (chemistry) ,Research Articles ,Cascade Reactions ,Multidisciplinary ,Metallic Surface ,Self Organizations ,SciAdv r-articles ,Física ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Methyl Radical ,Zigzag ,Chemical physics ,Intramolecular force ,Density functional theory ,0210 nano-technology ,Research Article ,Surface Chemistry ,Honeycomb Lattices - Abstract
Bottom-up surface-assisted synthesis of circumcoronene self-assembly enables realization of artificial electronic lattice., On-surface synthesis has revealed remarkable potential in the fabrication of atomically precise nanographenes. However, surface-assisted synthesis often involves multiple-step cascade reactions with competing pathways, leading to a limited yield of target nanographene products. Here, we devise a strategy for the ultrahigh-yield synthesis of circumcoronene molecules on Cu(111) via surface-assisted intramolecular dehydrogenation of the rationally designed precursor, followed by methyl radical-radical coupling and aromatization. An elegant electrostatic interaction between circumcoronenes and metallic surface drives their self-organization into an extended superlattice, as revealed by bond-resolved scanning probe microscopy measurements. Density functional theory and tight-binding calculations reveal that unique hexagonal zigzag topology of circumcoronenes, along with their periodic electrostatic landscape, confines two-dimensional electron gas in Cu(111) into a chiral electronic Kagome-honeycomb lattice with two emergent electronic flat bands. Our findings open up a new route for the high-yield fabrication of elusive nanographenes with zigzag topologies and their superlattices with possible nontrivial electronic properties.
- Published
- 2021
33. Ultra-high Yield On-surface Synthesis and Assembly of Circumcoronene into Chiral Electronic Kagome-honeycomb Lattice
- Author
-
Jishan Wu, Diego Soler-Polo, Guangwu Li, Shaotang Song, Pingo Mutombo, Xinnan Peng, Pavel Jelínek, Ming Joo Koh, Jiong Lu, Mykola Telychko, Jie Su, and Mark T. Edmonds
- Subjects
Scanning probe microscopy ,Materials science ,Zigzag ,Chemical physics ,Superlattice ,Honeycomb ,Molecule ,Density functional theory ,Non-contact atomic force microscopy ,Topology (chemistry) - Abstract
On-surface synthesis has revealed remarkable potential in the fabrication of a plethora of elusive nanographenes with tailored structural, electronic and magnetic properties unattainable by conventional wet-chemistry synthesis. Unfortunately, surface-assisted synthesis often involves multiple-step cascade reactions with competing pathways, leading to the formation of a diversity of products with limited yield, which reduces its feasibility towards the large-scale production for future technological applications. Here, we devise a new on-surface synthetic strategy for the ultra-high yield synthesis of a hexagonal nanographene with six zigzag edges, namely circumcoronene on Cu(111) via surfaceassisted intramolecular dehydrogenation of the rationally-designed precursor molecule, followed by methyl radical-radical coupling and aromatization. An elegant electrostatic interaction between circumcoronene and Cu(111) drives their self-organization into an extended superlattice, as revealed by bond-resolved low-temperature scanning probe microscopy and spectroscopy measurements. Density functional theory and tight-binding calculations reveal that unique hexagonal zigzag topology of circumcoronenes, along with their periodic electrostatic landscape confines two-dimensional (2D) electron gas in Cu(111) surface into chiral electronic Kagome-honeycomb lattice with two emergent electronic flat bands. Our findings open up a new route for the high-yield fabrication of elusive nanographenes with zigzag topologies and their novel 2D superlattices with possible nontrivial electronic properties towards their future technological applications.
- Published
- 2020
34. Stable Olympicenyl Radicals and Their π-Dimers
- Author
-
Zhe Sun, Wenping Hu, Jing Guo, Jun Xu, Yanfeng Dang, Jishan Wu, Qin Xiang, Zongcheng Gong, Shuaishuai Ding, Guangwu Li, Hoa Phan, Yanwei Gu, Zhaoyang Li, Zebing Zeng, and Zhanqiang Xu
- Subjects
Chemistry ,Radical ,Intermolecular force ,Aromaticity ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,law.invention ,symbols.namesake ,Crystallography ,Colloid and Surface Chemistry ,law ,symbols ,Van der Waals radius ,Singlet state ,Spectroscopy ,Ground state ,Electron paramagnetic resonance - Abstract
An olympicenyl radical, a spin 1/2 hydrocarbon radical with C2v symmetry and uneven spin distribution, remains elusive despite the considerable theoretical research interest. Herein, we report syntheses of two air-stable olympicenyl radical derivatives, OR1 and OR2, with half-life times (τ1/2) in air-saturated solution of 7 days and 34 days. The high stability was ascribed to kinetic blocking of reactive sites with high spin densities. X-ray crystallographic analysis revealed unique 20-center-2-electron head-to-tail π-dimer structures with intermolecular distances shorter than the sum of van der Waals radius of carbon. The ground state of the π-dimers was found to be singlet, with singlet-triplet energy gaps estimated to be -2.34 kcal/mol and -3.28 kcal/mol for OR1 and OR2, respectively, by variable-temperature electron spin resonance (ESR) spectroscopy. The monomeric radical species were in equilibrium with the π-dimer in solution, and the optical and electrochemical properties of the monomers and π-dimers in solution were investigated by UV-vis-NIR spectroscopy and cyclic voltammetry, revealing a concentration-dependent nature. Theoretical calculations illustrated that upon formation of a π-dimer the local aromaticity of each monomer was enhanced, and spatial ring current between the monomers was present, which resulted in an increment of aromaticity of the interior of the π-dimer.
- Published
- 2020
35. Exploring the mechanism of olfactory recognition in the initial stage by modeling the emission spectrum of electron transfer
- Author
-
Rao Fu, Guangwu Li, and Shu Liu
- Subjects
Social Sciences ,02 engineering and technology ,Electron Transfer ,Receptors, Odorant ,01 natural sciences ,Spectral line ,Emission Spectra ,Isotopes ,Hydrogen Cyanide ,Kinetic isotope effect ,Psychology ,Vibronic spectroscopy ,Emission spectrum ,Materials ,Multidisciplinary ,Organic Compounds ,Chemistry ,Physics ,Classical Mechanics ,food and beverages ,021001 nanoscience & nanotechnology ,Smell ,Chemical physics ,Benzaldehydes ,Physical Sciences ,Engineering and Technology ,Medicine ,Sensory Perception ,0210 nano-technology ,psychological phenomena and processes ,Research Article ,Science ,Cell Respiration ,Materials Science ,Material Properties ,Vibration Engineering ,Olfaction ,010402 general chemistry ,Vibration ,Olfactory Receptor Neurons ,Electron Transport ,Electron transfer ,Ab initio quantum chemistry methods ,Humans ,Molecule ,Nitrobenzenes ,Chemical Physics ,Mechanical Engineering ,Organic Chemistry ,Chemical Compounds ,Biology and Life Sciences ,Olfactory Perception ,0104 chemical sciences ,Odorants ,Neuroscience - Abstract
Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang–Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.
- Published
- 2020
36. Influence of substrate temperature on the film morphology and photovoltaic performance of non-fullerene organic solar cells
- Author
-
Hongmei Xiao, Guangwu Li, Sufei Xie, Cuihong Li, Zhen Lu, Xuejuan Zhang, Yang Wu, Zhishan Bo, Xuebo Chen, Wei Ma, and Jicheng Zhang
- Subjects
chemistry.chemical_classification ,Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,Open-circuit voltage ,Energy conversion efficiency ,Nanotechnology ,02 engineering and technology ,Polymer ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Active layer ,chemistry ,Chemical engineering ,0210 nano-technology ,HOMO/LUMO - Abstract
A novel 1,8-naphthalimide-based small molecular acceptor ( NI-T-C8 ) was designed and synthesized. The LUMO level of NI-T-C8 was high-lying, which would reduce the energy loss of WBG polymer PCDTBT-C12 based devices. When non-fullerene devices based on PCDTBT-C12: NI-T-C8 were spin-coated from substrates with a temperature of 30 °C, the aggregation of NI-T-C8 would lead to an unoptimized film morphology and result in a low power conversion efficiency (PCE) of 2.68%. After elevating the substrates from 30 to 45 °C, the domain size of blend films was decreased and a PCE of 3.61% with a high open circuit voltage ( V oc ) of 1.28 V was acquired, but the aggregation of NI-T-C8 for blend films fabricated in 45 °C based substrates was still influence the exciton dissociation in the active layers, lower J sc values for NI-T-C8 based devices in comparison to PC 71 BM based ones were therefore acquired. This is the first single junction organic solar cell with a PCE higher than 3% could achieve a V oc higher than 1.2 V. Our results also demonstrated that elevating the temperature of substrates could reduce the domain size of non-fullerene acceptors, which could provide a strategy to adjust the film morphology of active layer comprising easy-aggregating non-fullerene acceptor.
- Published
- 2018
37. Knowledge, attitude and intentions towards nursing profession among Chinese high school graduates in central China
- Author
-
Kenneth J. Gruber, Guangwu Li, Yuye Ke, Li Li, Jie Hu, and Shuzhen Zhu
- Subjects
Demographics ,Nursing ,education ,Multilevel model ,Central china ,Economic shortage ,Social media ,Future career ,Family income ,China ,Psychology - Abstract
Background and objective: Current nursing shortages and low willingness of young people to choose nursing as a career are of major concern in many countries. This study examined the knowledge, attitude and intention towards the nursing profession among high school graduates in China and factors associated with graduate’ intention to enroll in nursing program. Methods: A cross-sectional study was conducted using a random sampling. A total of 3,764 high school graduates of selected schools in Central China participated in the study. Data were collected with online survey including demographics, knowledge of and attitude towards nursing and intention to choose nursing. Pearson’s correlations and Hierarchical regression analyses were performed. Results: Less than 10% of the participants expressed interest in a future career in nursing. Knowledge and attitude about nursing were positively associated with intention to study nursing. Both participants’ education, family income and attitude significantly predicted intention to study nursing in the hierarchy regression model ( p < .001). Conclusions: Recruitment and retention strategies need to focus on addressing improving knowledge about the roles of nurse among high school students. Nursing administrators and educators should provide information about nursing profession on Websites and social media or programs for high school students with early clinical exposure to nursing to increase their knowledge and change their attitudes toward nursing.
- Published
- 2021
38. Data on the detail information of influence of substrate temperature on the film morphology and photovoltaic performance of non-fullerene organic solar cells
- Author
-
Xuejuan Zhang, Guangwu Li, Yang Wu, Zhen Lu, Jicheng Zhang, Xuebo Chen, Hongmei Xiao, Cuihong Li, Sufei Xie, Zhishan Bo, and Wei Ma
- Subjects
Materials science ,Fullerene ,Morphology (linguistics) ,Organic solar cell ,Materials Science ,Nanotechnology ,02 engineering and technology ,Substrate (electronics) ,lcsh:Computer applications to medicine. Medical informatics ,010402 general chemistry ,01 natural sciences ,Polymer solar cell ,law.invention ,law ,Solar cell ,lcsh:Science (General) ,Multidisciplinary ,business.industry ,Photovoltaic system ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Characterization (materials science) ,lcsh:R858-859.7 ,Optoelectronics ,0210 nano-technology ,business ,lcsh:Q1-390 - Abstract
This data contains additional data related to the article “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” (Jicheng Zhang et al., In press) [1]. Data include measurement and characterization instruments and condition, detail condition to fabricate norfullerene solar cell devices, hole-only and electron-only devices. Detail condition about how to control the film morphology of devices via tuning the temperature of substrates was also displayed. More information and more convincing data about the change of film morphology for active layers fabricated from different temperature, which is attached to the research article of “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” was given.
- Published
- 2017
39. Improve the diagnosis of idiopathic normal pressure hydrocephalus by combining abnormal cortical thickness and ventricular morphometry
- Author
-
Yifeng Yang, Meijing Yan, Xiao Liu, Shihong Li, and Guangwu Lin
- Subjects
idiopathic normal pressure hydrocephalus (iNPH) ,brain morphometry ,machine learning ,multi-feature fusion ,diagnosis ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
BackgroundThe primary imaging markers for idiopathic Normal Pressure Hydrocephalus (iNPH) emphasize morphological measurements within the ventricular system, with no attention given to alterations in brain parenchyma. This study aimed to investigate the potential effectiveness of combining ventricular morphometry and cortical structural measurements as diagnostic biomarkers for iNPH.MethodsA total of 57 iNPH patients and 55 age-matched healthy controls (HC) were recruited in this study. Firstly, manual measurements of ventricular morphology, including Evans Index (EI), z-Evans Index (z-EI), Cella Media Width (CMW), Callosal Angle (CA), and Callosal Height (CH), were conducted based on MRI scans. Cortical thickness measurements were obtained, and statistical analyses were performed using surface-based morphometric analysis. Secondly, three distinct models were developed using machine learning algorithms, each based on a different input feature: a ventricular morphology model (LVM), a cortical thickness model (CT), and a fusion model (All) incorporating both features. Model performances were assessed using 10-fold cross validation and tested on an independent dataset. Model interpretation utilized Shapley Additive Interpretation (SHAP), providing a visualization of the contribution of each variable in the predictive model. Finally, Spearman correlation coefficients were calculated to evaluate the relationship between imaging biomarkers and clinical symptoms.ResultsiNPH patients exhibited notable differences in cortical thickness compared to HC. This included reduced thickness in the frontal, temporal, and cingulate cortices, along with increased thickness in the supracentral gyrus. The diagnostic performance of the fusion model (All) for iNPH surpassed that of the single-feature models, achieving an average accuracy of 90.43%, sensitivity of 90.00%, specificity of 90.91%, and Matthews correlation coefficient (MCC) of 81.03%. This improvement in accuracy (6.09%), sensitivity (11.67%), and MCC (11.25%) compared to the LVM strategy was significant. Shap analysis revealed the crucial role of cortical thickness in the right isthmus cingulate cortex, emerging as the most influential factor in distinguishing iNPH from HC. Additionally, significant correlations were observed between the typical triad symptoms of iNPH patients and cortical structural alterations.ConclusionThis study emphasizes the significant role of cortical structure changes in the diagnosis of iNPH, providing a novel insights for assisting clinicians in improving the identification and detection of iNPH.
- Published
- 2024
- Full Text
- View/download PDF
40. Variability scaling and capacity planning in Covid-19 pandemic
- Author
-
L. Jeff Hong, Guangwu Liu, Jun Luo, and Jingui Xie
- Subjects
Covid-19 ,Capacity planning ,Variability scaling ,Demand aggregation ,Network model ,Risk pooling effect ,Science (General) ,Q1-390 - Abstract
Capacity planning is a very important global challenge in the face of Covid-19 pandemic. In order to hedge against the fluctuations in the random demand and to take advantage of risk pooling effect, one needs to have a good understanding of the variabilities in the demand of resources. However, Covid-19 predictive models that are widely used in capacity planning typically often predict the mean values of the demands (often through the predictions of the mean values of the confirmed cases and deaths) in both the temporal and spatial dimensions. They seldom provide trustworthy prediction or estimation of demand variabilities, and therefore, are insufficient for proper capacity planning. Motivated by the literature on variability scaling in the areas of physics and biology, we discovered that in the Covid-19 pandemic, both the confirmed cases and deaths exhibit a common variability scaling law between the average of the demand μ and its standard deviation σ, that is, σ∝μβ, where the scaling parameter β is typically in the range of 0.65 to 1, and the scaling law exists in both the temporal and spatial dimensions. Based on the mechanism of contagious diseases, we further build a stylized network model to explain the variability scaling phenomena. We finally provide simple models that may be used for capacity planning in both temporal and spatial dimensions, with only the predicted mean demand values from typical Covid-19 predictive models and the standard deviations of the demands derived from the variability scaling law.
- Published
- 2023
- Full Text
- View/download PDF
41. Enhancing the Performance of Polymer Solar Cells by Using Donor Polymers Carrying Discretely Distributed Side Chains
- Author
-
Xue Gong, Shiyu Feng, Yahui Liu, Jicheng Zhang, Cuihong Li, Wei Ma, Zhishan Bo, Yang Wu, and Guangwu Li
- Subjects
chemistry.chemical_classification ,Materials science ,Stacking ,02 engineering and technology ,Polymer ,Conjugated system ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,chemistry.chemical_compound ,Polymerization ,Chemical engineering ,chemistry ,Polymer chemistry ,Thiophene ,Side chain ,General Materials Science ,0210 nano-technology - Abstract
Conjugated polymers with three components, P1-1 and P1-2, were prepared by one-pot Stille polymerization. The two-component polymer P1-0 is only composed of a 5-fluoro-6-alkyloxybenzothiadiazole (AFBT) acceptor unit and a thiophene donor unit, while the three-component polymers P1-1 and P1-2 contain 10% and 20% 5,6-difluorobenzothiadiazole (DFBT), respectively, as the third component. The incorporation of the third component, 5,6-difluorobenzothiadiazole, makes the side chains discretely distributed in the polymer backbones, which can enhance the π–π stacking of polymers in film, markedly increase the hole mobility of active layers, and improve the power-conversion efficiency (PCE) of devices. Influence of the third component on the morphology of active layer was also studied by X-ray diffraction (XRD), resonant soft X-ray scattering (R-SoXS), and transmission electron microscopy (TEM) experiments. P1-1/PC71BM-based PSCs gave a high PCE up to 7.25%, whereas similarly fabricated devices for P1-0/PC71BM onl...
- Published
- 2017
42. Insights into the influence of fluorination positions on polymer donor materials on photovoltaic performance
- Author
-
Zhishan Bo, Danyang Ma, Guangwu Li, Xue Gong, Wei Ma, Jianya Chen, Ran Hou, Cuihong Li, and Shiyu Feng
- Subjects
Condensation polymer ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Polymer solar cell ,Biomaterials ,chemistry.chemical_compound ,Quinoxaline ,Materials Chemistry ,Copolymer ,Organic chemistry ,Electrical and Electronic Engineering ,chemistry.chemical_classification ,Energy conversion efficiency ,General Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Acceptor ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Fluorine ,0210 nano-technology - Abstract
To explore the influence of fluoro substitution position and number on optical, electrochemical and photovoltaic properties, three novel donor-acceptor (D-A) alternative copolymers (PHF, PFH and PFF) were synthesized by Stille polycondensation of 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (DTQx) acceptor unit and indacenodithiophene (IDT) donor unit. As films, PHF and PFF comprising two fluoro substituents on the lateral phenyl groups displayed a broad absorption ranging from 350 to 700 nm; whereas PFH containing two fluorine atoms on the polymer main chain exhibited a slightly narrower absorption ranging from 350 to 650 nm. In addition, fluoro substitution on the polymer main chain can lower the HOMO level of the resulted polymers. As expected, PFH and PFF possess deeper HOMO energy level than PHF. Polymer solar cells (PSCs) were fabricated with these three polymers as donor materials and PC71BM as acceptor material. PHF based PSCs gave a power conversion efficiency (PCE) of 7.2% with a Voc of 0.84 V, a Jsc of 12.46 mA/cm2 and an FF of 0.69. And PFH based PSCs showed a PCE of 6.19% with a Voc of 0.93 V, a Jsc of 9.57 mA/cm2 and an FF 0.70. However, a PCE of only 2.9% with a Voc of 0.92 V, a Jsc of 4.61 mA/cm2 and an FF of 0.68 was obtained for PFF based PSCs. Transmission electron microscopy (TEM) and resonant soft X-ray scattering (R-SoXS) studies indicated that the introduction of four fluorine atoms at each repeating unit can spoil the morphology of active layer. These results highlight the importance of fluorination position and number to the performance of PSCs.
- Published
- 2017
43. Finely designed medium-band-gap polymer donor with judiciously selecting chalcogen atom for high efficiency polymer solar cell
- Author
-
Shiyu Feng, Yahui Liu, Cuihong Li, Xue Gong, Ran Hou, Zhe Zhang, Zhishan Bo, and Guangwu Li
- Subjects
chemistry.chemical_classification ,Materials science ,Band gap ,Process Chemistry and Technology ,General Chemical Engineering ,Inorganic chemistry ,Energy conversion efficiency ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,Crystallinity ,chemistry ,Chemical engineering ,Copolymer ,Side chain ,0210 nano-technology - Abstract
A novel medium band gap copolymer ( PBO ) based on benzodithiophene (BDT) and benzoxadiazole (BOz) was synthesized and applied in polymer solar cells (PSCs). The introduction of two alkylthio side chains onto the BDT unit can endow the resulting polymer ( PBO ) with good solubility in solutions and good crystallinity in the solid state. The low HOMO level of −5.52 eV and the broad absorption ranging from 350 to 700 nm make PBO a promising donor material for PSCs. Power conversion efficiency higher than 7% has been achieved for devices using PBO as the donor material and PC 71 BM or ITIC as the acceptor material.
- Published
- 2017
44. Influence of polymer side chains on the photovoltaic performance of non-fullerene organic solar cells
- Author
-
Xuebo Chen, Xue Gong, Zhishan Bo, Cuihong Li, Ran Hou, Liangliang Wu, Guangwu Li, Shiyu Feng, and Yahui Liu
- Subjects
chemistry.chemical_classification ,Materials science ,Organic solar cell ,Substituent ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Materials Chemistry ,Alkoxy group ,Side chain ,0210 nano-technology ,HOMO/LUMO - Abstract
Novel polymers comprising a 3-fluoro-5-alkylthiophenyl benzodithiophene donor unit and a 5-fluoro-6-alkoxy (or alkylthio)-2,1,3-benzothiadiazole (BT) acceptor unit were synthesized. Both POF and PSF possess low HOMO and LUMO energy levels due to the incorporation of fluorine atoms. Additionally, alkoxy and alkylthio substitution on the BT unit also had a great influence on the molecular packing and the energy level of the resulting polymers. The introduction of the alkylthio side chains on the BT unit of PSF led to a significant downshift of the HOMO energy level in comparison to that of POF with an alkoxy substituent due to the weaker electron-donating properties of the sulfur atom than that of oxygen. However, the steric hindrance caused by the large sulfur atoms resulted in reduced planarity of the backbone of PSF, which might influence the charge transport and the morphology of the blend film. As a result, POF based NF-PSCs exhibited a PCE of 7.28%, with a Voc of 0.86 V, a Jsc of 14.9 mA cm−2, and an FF of 0.47, while a low PCE of 1.55% with a Voc of 0.95 V, a Jsc of 5.6 mA cm−2, and an FF of 0.29 was obtained for PSF based non-fullerene polymer solar cells (NF-PSCs). Therefore, the side chain engineering of the donor polymer is crucial for maximizing both Jsc and Voc values to achieve high performance polymer solar cells.
- Published
- 2017
45. Hyperbranched polymer as an acceptor for polymer solar cells
- Author
-
Xuebo Chen, Xuejuan Zhang, Zhen Lu, Cuihong Li, Hongmei Xiao, Xinjun Xu, Zhishan Bo, Guangwu Li, Sufei Xie, and Jicheng Zhang
- Subjects
chemistry.chemical_classification ,Materials science ,Energy conversion efficiency ,Metals and Alloys ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Catalysis ,Polymer solar cell ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Chemical engineering ,Materials Chemistry ,Ceramics and Composites ,Molecule ,0210 nano-technology - Abstract
For the first time, a hyperbranched polymer acceptor, HP-PDI, was designed, synthesized and applied in polymer solar cells (PSCs). Devices based on HP-PDI showed a power conversion efficiency of 2.15%, which is 14 times higher than that of devices based on the small molecular acceptor SM-PDI. The hyperbranched structure can effectively suppress the aggregation of PDI molecules preventing them from forming large domains. Our preliminary results have demonstrated that high efficiency PSCs could be achieved by using a hyperbranched polymer acceptor.
- Published
- 2017
46. Implementing Ecological Paradigm Teaching Strategy on Sports Class Quality of China: An Action Research Study of a College Sports Class.
- Author
-
Guangwu Li and LeeHsing Lu
- Subjects
COLLEGE sports ,SPORTS psychology ,ACTION research ,ATHLETIC ability ,STUDENT health - Abstract
Purpose- As the health of Chinese college students continues to decline, people realize that the quality of college sport class quality is one of the main factors affecting student health. This research is through ODI to change the teaching strategy, and improve the sports motivation, sports ability and Satisfaction with teachers. It will verify the effectiveness and feasibility of ODI methods in China's sport class. Design/Methodology/Approach- Use a dual experimental group design, combination of qualitative and quantitative action research. Collect qualitative and quantitative data before and after ODI, Pairedsample t-test, Pearson correlation, and regression analysis were used to determine. This organization is a public university in the south of China. sports teachers (n=3), college students (n=127). Findings- The implementation of ODI can significantly improve sports class quality; There is a significant causal relationship between the independent variables of ecological paradigm teaching strategy (Leadership, Managerial, Social, Vector, Instructional) and the dependent variables of Sports class quality; the dependent variables (Sports motivation, Sports ability, Satisfaction with teachers) are highly correlated, Intervention of one factor can predict another factor. Practical Implications- The research will have a positive impact on the health of Shaoguan University students; The results will be used as reference for the improvement of physical education teaching in Chinese universities. Originality/Value- The study verifies the feasibility of organizational development intervention methods in Chinese sport classes; Put forward the "Ecological Paradigm Teaching Strategy Model"; Summarizes the theoretical framework, conceptual framework and action basis; it is an innovative research based on the combination of organizational development and sports class. [ABSTRACT FROM AUTHOR]
- Published
- 2021
47. MiR-940 Inhibited Cell Growth and Migration in Triple-Negative Breast Cancer
- Author
-
Xiaobo Zhao, Jiani Hu, Lina Zhang, Jingdong Li, Hongwei Yang, Shishan Deng, Jun Jiang, Tianyong Xing, Maoshan Chen, Lingmi Hou, and Guangwu Li
- Subjects
0301 basic medicine ,CA15-3 ,Pathology ,medicine.medical_specialty ,Kruppel-Like Transcription Factors ,Triple Negative Breast Neoplasms ,Biology ,03 medical and health sciences ,0302 clinical medicine ,Breast cancer ,Western blot ,Cell Movement ,Cell Line, Tumor ,microRNA ,medicine ,Humans ,Molecular Biology ,Cells, Cultured ,Triple-negative breast cancer ,Cell Proliferation ,medicine.diagnostic_test ,Cell growth ,Cancer ,General Medicine ,Prognosis ,medicine.disease ,Gene Expression Regulation, Neoplastic ,MicroRNAs ,030104 developmental biology ,030220 oncology & carcinogenesis ,Cancer research ,Female ,Cell Migration Assays - Abstract
BACKGROUND Breast cancer is the main type of cancer in women, and triple-negative breast cancer (TNBC) is a unique subtype of breast cancer. The expression of miR-940 has been shown to play an important role in various cancers; however, the role of miR-940 in TNBC remains unknown. MATERIAL AND METHODS The expression of miR-940 in TNBC tissues or cells were tested by qRT-PCR; the expression of miR-940 in cells were overexpressed by miR-940 mimics, and suppressed by anti-miR-940. Bioinformatics algorithms from TargetScanHuman were used to predict the target genes of miR-940. The interaction between miR-940 and ZNF24 was confirmed by dual luciferase assays. The protein level was assayed by Western blot. RESULTS TNBC tissues and cells showed lower miR-940 levels. CONCLUSIONS MiR-940 inhibited cellular proliferation and migration in TNBC.
- Published
- 2016
48. Dearomatization Approach Toward a Superbenzoquinone-Based Diradicaloid, Tetraradicaloid, and Hexaradicaloid
- Author
-
Johnathan Joo Cheng Lee, Guangwu Li, Ya Zou, Yi Han, Jishan Wu, and Yong Ni
- Subjects
chemistry.chemical_classification ,Ketone ,010405 organic chemistry ,Radical ,Polycyclic aromatic hydrocarbon ,Aromaticity ,General Medicine ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Active space ,Character (mathematics) ,chemistry ,Computational chemistry ,Spectroscopy - Abstract
Reported here is the step-by-step dearomatization of a highly aromatic polycyclic aromatic hydrocarbon (PAH), the hexa-peri-hexabenzocoronene (also called as "superbenzene"), to give a series of superbenzoquinones containing two, four, and six ketone groups. Different from traditional PAH-based quinones, these superbenzoquinones show open-shell multiradical character by rearomatization in the open-shell forms as experimentally validated by X-ray crystallographic analysis, NMR and ESR spectroscopy, and FT-IR measurements, as well as theoretically supported by restricted active space spin-flip calculations. These compounds exhibit structure- and molecular-symmetry-dependent optical, electrochemical, and magnetic properties.
- Published
- 2019
49. Exploring the Mechanism of Olfactory Recognition at the Initial Stage by Modeling the Emission Spectrum of Electron Transfer
- Author
-
Shu Liu, Rao Fu, and Guangwu Li
- Subjects
Electron transfer ,Chemical physics ,Chemistry ,Ab initio quantum chemistry methods ,Kinetic isotope effect ,Vibronic spectroscopy ,Molecule ,food and beverages ,Emission spectrum ,Olfaction ,Spectral line ,psychological phenomena and processes - Abstract
Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang–Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.
- Published
- 2019
- Full Text
- View/download PDF
50. Machine Vision Automated Chiral Molecule Detection and Classification in Molecular Imaging.
- Author
-
Jiali Li, Mykola Telychko, Jun Yin, Yixin Zhu, Guangwu Li, Shaotang Song, Haitao Yang, Jing Li, Jishan Wu, Jiong Lu, and Xiaonan Wang
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.