Journal articles on the topic 'Triplets de frontière'
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1
Qian, Yan, Yeren Ni, Shouzhen Yue, Wenwen Li, Shufen Chen, Zhensong Zhang, Linghai Xie, Mingli Sun, Yi Zhao, and Wei Huang. "Spiro[fluorene-9,9′-xanthene]-based universal hosts for understanding structure–property relationships in RGB and white PhOLEDs." RSC Advances 5, no. 38 (2015): 29828–36. http://dx.doi.org/10.1039/c5ra00694e.
2
Jiang, Jie, Shengwei Guo, Xiaorong Wang, Liyan Xu, Qiang Li, and Xiaoxin Zhang. "Theoretical investigation of the structural and spectroscopic properties of expanded metalloporphyrin complexes." Royal Society Open Science 6, no. 1 (January 2019): 181199. http://dx.doi.org/10.1098/rsos.181199.
Abstract:
The frontier molecular orbitals, UV–Vis absorption spectra, charge transfer (CT) and triplet excited states of 12 expanded D–A porphyrin/benzoporphyrin complexes were investigated using the density functional theory (DFT) method and time-dependent DFT in this work. The results showed that thiophene was an effective fragment for absorption of ‘long wavelength’, while the benzoporphyrin worked on the ‘short wavelength’, which was derived from its saddle-shaped structure; this expanded D–A conjugated system had a mild CT process with anthraquinone/isoindigo as acceptors and a strong CT process with naphtoquinone as acceptor. In addition, based on the simulation of the triplet state, the theoretical phosphorescence wavelength range of this series of derivatives was between 1000 and 1200 nm. This study is expected to assist the design of conjugated porphyrin for the field of porphyrin chemistry.
3
Wijesinghe, Channa A., Marja Niemi, Nikolai V. Tkachenko, Navaneetha K. Subbaiyan, Melvin E. Zandler, Helge Lemmetyinen, and Francis D'Souza. "Photoinduced electron transfer in a directly linked meso-triphenylamine zinc porphyrin-quinone dyad." Journal of Porphyrins and Phthalocyanines 15, no. 05n06 (May 2011): 391–400. http://dx.doi.org/10.1142/s108842461100329x.
Abstract:
A multimodular donor-acceptor system composed of three triphenylamine entities at the meso-positions of a zinc porphyrin macrocycle and a quinone at the fourth meso-position was newly synthesized and characterized. The triphenylamine entities acted as energy transferring antenna units in addition of improving the electron donor ability of the zinc porphyrin. Appreciable electronic interactions of the triphenylamine and quinone entities with the porphyrin π-system were observed. In agreement with the spectral and electrochemical results, the computational studies performed by the DFT B3LYP/3-21G(*) method revealed delocalization of the frontier HOMO over the triphenylamine and the porphyrin macrocycle while the LUMO to be fully localized over the quinone entity. Free-energy calculations suggested photoinduced electron transfer from the singlet excited zinc porphyrin to the directly linked quinone to be exothermic and this was experimentally confirmed by the time-resolved pump probe and up-conversion techniques. In the investigated system, the ET reaction path was found to depend upon the excitation wavelength. That is, when Zn porphyrin was predominantly excited, a rapid charge separation followed by equally fast charge recombination was observed. However, excitation of the peripheral TPA substituents resulted in an extremely long-lived CS state with triplet spin character via the TPA triplet and Zn porphyrin triplet states.
4
Ewen, Pascal R., Jan Sanning, Tobias Koch, Nikos L. Doltsinis, Cristian A. Strassert, and Daniel Wegner. "Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials." Beilstein Journal of Nanotechnology 5 (November 26, 2014): 2248–58. http://dx.doi.org/10.3762/bjnano.5.234.
Abstract:
The improvement of molecular electronic devices such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS) are powerful tools to correlate the electronic properties of phosphorescent complexes (i.e., triplet emitters) with their molecular structure as well as the local environment around a single molecule. We used spectroscopic mapping to visualize several occupied and unoccupied molecular frontier orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well-defined positions can alter specific molecular orbitals without influencing the others. The results open a path toward the tailored design of electronic and optical properties of triplet emitters by smart ligand substitution, which may improve the performance of future OLED devices.
5
Siegert, Benjamin, Andrea Donarini, and Milena Grifoni. "Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine." Beilstein Journal of Nanotechnology 6 (December 22, 2015): 2452–62. http://dx.doi.org/10.3762/bjnano.6.254.
Abstract:
The interplay of exchange correlations and spin–orbit interaction (SOI) on the many-body spectrum of a copper phtalocyanine (CuPc) molecule and their signatures in transport are investigated. We first derive a minimal model Hamiltonian in a basis of frontier orbitals that is able to reproduce experimentally observed singlet–triplet splittings. In a second step SOI effects are included perturbatively. Major consequences of the SOI are the splitting of former degenerate levels and a magnetic anisotropy, which can be captured by an effective low-energy spin Hamiltonian. We show that scanning tunneling microscopy-based magnetoconductance measurements can yield clear signatures of both these SOI-induced effects.
6
Langlois, Adam, Hai-Jun Xu, Paul-Ludovic Karsenti, Claude P. Gros, and Pierre D. Harvey. "Very fast singlet and triplet energy transfers in a tri-chromophoric porphyrin dyad aided by the truxene platform." Journal of Porphyrins and Phthalocyanines 19, no. 01-03 (January 2015): 427–41. http://dx.doi.org/10.1142/s1088424615500327.
Abstract:
A trichromophoric dyad composed of an octa-β-alkyl-palladium(II)porphyrin (donor) and two tri-meso-aryl-zinc(II)porphyrins (acceptors) held by a truxene spacer exhibits very fast rates for triplet energy transfers at 77 (kET(T1) = 1.63 × 108 s-1) and 298 K (kET(T1) = 3.44 × 108 s-1), whereas the corresponding singlet energy transfer rates, kET(S1) = 3.9 × 1010 s-1 (77 K) and kET(S1) = 6.0 × 1010 s-1 (298 K), are also considered fast. The interpretation for these results is that the energy transfer processes proceed via a through bond Dexter mechanism (i.e. double electron exchange) supported by comparison with literature data and evidence for a moderate MO coupling between the donor and acceptor chromophores in the frontier MOs.
7
Watts, Jonathan K., and Masad J. Damha. "2′F-Arabinonucleic acids (2′F-ANA) — History, properties, and new frontiers." Canadian Journal of Chemistry 86, no. 7 (July 1, 2008): 641–56. http://dx.doi.org/10.1139/v08-049.
Abstract:
The development of arabinonucleosides and oligoarabinonucleotides is described, focusing especially on 2′-deoxy-2′-fluoroarabinonucleosides (araF-N) and -oligonucleotides (2'F-ANA). In addition to their chemical and enzymatic synthesis, we discuss various properties of 2′F-ANA: hydrolytic stability (to nucleases, acids, and bases), binding affinity to complementary strands, structure and conformation, and optimization of RNase H activity. We also discuss the use of 2′F-ANA in gene-silencing approaches (antisense, siRNA), and in the stabilization of higher-order structures (such as triplexes and quadruplexes) including aptamers. Finally, we examine several other oligonucleotide derivatives based on 2′F-ANA and look ahead to the future of 2′-fluoroarabinonucleosides and -oligonucleotides.Key words: arabinonucleic acids, 2′F-ANA, antisense oligonucleotides, siRNA, modified oligonucleotides.
8
Ren, Zhongqiang, Jiaoyang Li, Han Zhang, Sven Koenig, Sivakumar Rathinam, and Howie Choset. "Binary Branching Multi-Objective Conflict-Based Search for Multi-Agent Path Finding." Proceedings of the International Conference on Automated Planning and Scheduling 33, no. 1 (July 1, 2023): 361–69. http://dx.doi.org/10.1609/icaps.v33i1.27214.
Abstract:
This paper considers a multi-agent multi-objective path-finding problem that requires not only finding collision-free paths for multiple agents from their respective start locations to their respective goal locations but also optimizing multiple objectives simultaneously. In general, there is no single solution that optimizes all the objectives simultaneously, and the problem is thus to find the so-called Pareto-optimal frontier. To solve this problem, an algorithm called Multi-Objective Conflict-Based Search (MO-CBS) was recently developed and is guaranteed to find the exact Pareto-optimal frontier. However, MO-CBS does not scale well with the number of agents due to the large branching factor of the search, which leads to a lot of duplicated effort in agent-agent collision resolution. This paper therefore develops a new algorithm called Binary Branching MO-CBS (BB-MO-CBS) that reduces the branching factor as well as the duplicated collision resolution during the search, which expedites the search as a result. Our experimental results show that BB-MO-CBS reduces the number of conflicts by up to two orders of magnitude and often doubles or triples the success rates of MO-CBS on various maps given a runtime limit.
9
Arsentyeva, Irina. "The Triple Frontier of Brazil, Argentina and Paraguay: Current State and Prospects for Development." IBEROAMERICA, no. 3 (2020): 121–44. http://dx.doi.org/10.37656/s20768400-2020-3-06.
10
Dick, David G., and Douglas W. Stephan. "Structure and magnetic properties of [Cp2M(μ-PEt2)]2 (M = Ti, Zr)." Canadian Journal of Chemistry 69, no. 7 (July 1, 1991): 1146–52. http://dx.doi.org/10.1139/v91-170.
Abstract:
The complex [Cp2Ti(μ-PEt2)]2 (1) crystallizes in the monoclinic space group P21/n with a = 16.591(3) Å, b = 8.662(2) Å, c = 37.407(2) Å, β = 102.40(1)°, Z = 8, and V = 5250(2) Å3. The Ti2P2 core of the dimeric complex is planar and the angles at Ti and P are close to 90°. The Ti … Ti separations were found to be 3.732(1) and 3.706(1) Å in the two independent molecules in the unit cell. Bulk magnetic susceptibility measurements on solid 1 show that the species is diamagnetic over the range 5–340 K. The coupling constant for the antiferromagnetic interaction between the Ti centers of 1 is found to be at least −300 cm−1. Extended Hückel Molecular Orbital calculations suggest that mixing of the frontier 1a1 orbitals of the Cp2Ti fragments with the p orbitals of the phosphide fragments affords a mechanism for super-exchange through the ligands. In THF solution, variable temperature 1H, and 31P{1H} NMR and EPR spectra for 1 are consistent with the generation of the paramagnetic monomeric species Cp2TiPEt2, 3. As well, the data suggest thermal populations of the paramagnetic triplet state of the dimer may occur to a small extent at 340 K. In contrast, the analogous Zr dimer 2 shows no evidence of dissociation or of thermal population of the triplet state at temperatures to 340 K. Key words: titanium phosphides, structures, magnetic properties.
11
Sampson, Thomas. "Dynamic Selection: An Idea Flows Theory of Entry, Trade, and Growth *." Quarterly Journal of Economics 131, no. 1 (September 4, 2015): 315–80. http://dx.doi.org/10.1093/qje/qjv032.
Abstract:
Abstract This article develops an idea flows theory of trade and growth with heterogeneous firms. Entrants learn from incumbent firms, and the diffusion technology is such that learning depends not on the frontier technology, but on the entire distribution of productivity. By shifting the productivity distribution upward, selection causes technology diffusion, and in equilibrium this dynamic selection process leads to endogenous growth without scale effects. On the balanced growth path, the productivity distribution is a traveling wave with a lower bound that increases over time. The free entry condition implies trade liberalization must increase the dynamic selection rate to offset the profits from new export opportunities. Consequently, trade integration raises long-run growth. Dynamic selection is a new source of gains from trade not found when firms are homogeneous. Calibrating the model implies dynamic selection approximately triples the gains from trade compared to heterogeneous firm economies with static steady states.
12
Liu, Hengjia, and Guohua Xie. "Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons." Beilstein Journal of Organic Chemistry 18 (July 12, 2022): 825–36. http://dx.doi.org/10.3762/bjoc.18.83.
Abstract:
The changes in absorption and emission of fluorescent materials with the introduction of Lewis acids have been frequently observed due to either physical or chemical interactions. In this mini-review, we elaborate how Lewis acids adjust the optical properties and the bandgap of luminescent materials by simple coordination reactions. It is common that fluorescent materials containing Lewis basic nitrogen heterocycles are more likely to provide the feasible band gap modulation. The essence of such phenomenon originates from Lewis acid–base coordination and adducts, which highly depends on the electron-accepting property of the Lewis acids. This intermolecular mechanism, considered as post-synthesis of new luminescent compounds offers promising applications in sensing and electroluminescence by manipulating the frontier molecular orbital energy levels of organic conjugated materials, simply based on Lewis acid–base chemistry.
13
Gümüş, Selçuk, and Ayşegül Gümüş. "A computational study on a series of phenanthrene and phenanthroline based potential organic photovoltaics." Macedonian Journal of Chemistry and Chemical Engineering 36, no. 2 (November 29, 2017): 239. http://dx.doi.org/10.20450/mjcce.2017.1199.
Abstract:
A series of phenanthrene and phenanthroline derivatives were considered computationally by the application of Density Functional Theory at the B3LYP/6-31++G(d,p) level to investigate their potential usage as organic solar cell components, thermally activated delayed fluorescence and nonlinear optic compounds. The structures were constructed as a D-π-A motif in order to increase the ability to achieve intramolecular charge transfer enabling them to act as organic semiconductors. The inter-frontier energy gap of all compounds was found to be in the range of semiconductors. The thermally activated delayed fluorescence (TADF) properties of the compounds were also discussed in relation to the results obtained by TD-DFT calculations. Some of them possessed very narrow triplet-singlet transition energy leading to future TADF applications. Moreover, the nonlinear optic characteristics of all compounds were investigated through calculations of the total molecular dipole moment (μtot), linear polarizability (αtot) and hyperpolarizability (βtot). The results indicate the potential nonlinear optic property of all of the systems.
14
Ponte, Fortuna, Davide Maria Scopelliti, Nico Sanna, Emilia Sicilia, and Gloria Mazzone. "How Computations Can Assist the Rational Design of Drugs for Photodynamic Therapy: Photosensitizing Activity Assessment of a Ru(II)-BODIPY Assembly." Molecules 27, no. 17 (September 1, 2022): 5635. http://dx.doi.org/10.3390/molecules27175635.
Abstract:
Ruthenium-based complexes represent a new frontier in light-mediated therapeutic strategies against cancer. Here, a density functional-theory-based computational investigation, of the photophysical properties of a conjugate BODIPY-Ru(II) complex, is presented. Such a complex was reported to be a good photosensitizer for photodynamic therapy (PDT), successfully integrating the qualities of a NIR-absorbing distyryl-BODIPY dye and a PDT-active [Ru(bpy)3]2+ moiety. Therefore, the behaviour of the conjugate BODIPY-Ru(II) complex was compared with those of the metal-free BODIPY chromophore and the Ru(II) complex. Absorptions spectra, excitation energies of both singlet and triplet states as well as spin–orbit-matrix elements (SOCs) were used to rationalise the experimentally observed different activities of the three potential chromophores. The outcomes evidence a limited participation of the Ru moiety in the ISC processes that justifies the small SOCs obtained for the conjugate. A plausible explanation was provided combining the computational results with the experimental evidences.
15
Abdullah, Taghreed, Yakoub Bazi, Mohamad M. Al Rahhal, Mohamed L. Mekhalfi, Lalitha Rangarajan, and Mansour Zuair. "TextRS: Deep Bidirectional Triplet Network for Matching Text to Remote Sensing Images." Remote Sensing 12, no. 3 (January 27, 2020): 405. http://dx.doi.org/10.3390/rs12030405.
Abstract:
Exploring the relevance between images and their respective natural language descriptions, due to its paramount importance, is regarded as the next frontier in the general computer vision literature. Thus, recently several works have attempted to map visual attributes onto their corresponding textual tenor with certain success. However, this line of research has not been widespread in the remote sensing community. On this point, our contribution is three-pronged. First, we construct a new dataset for text-image matching tasks, termed TextRS, by collecting images from four well-known different scene datasets, namely AID, Merced, PatternNet, and NWPU datasets. Each image is annotated by five different sentences. All the five sentences were allocated by five people to evidence the diversity. Second, we put forth a novel Deep Bidirectional Triplet Network (DBTN) for text to image matching. Unlike traditional remote sensing image-to-image retrieval, our paradigm seeks to carry out the retrieval by matching text to image representations. To achieve that, we propose to learn a bidirectional triplet network, which is composed of Long Short Term Memory network (LSTM) and pre-trained Convolutional Neural Networks (CNNs) based on (EfficientNet-B2, ResNet-50, Inception-v3, and VGG16). Third, we top the proposed architecture with an average fusion strategy to fuse the features pertaining to the five image sentences, which enables learning of more robust embedding. The performances of the method expressed in terms Recall@K representing the presence of the relevant image among the top K retrieved images to the query text shows promising results as it yields 17.20%, 51.39%, and 73.02% for K = 1, 5, and 10, respectively.
16
Fosu, Emmanuel Adu, Collins Obuah, Louis Hamenu, Albert Aniagyei, Michael Kojo Ainooson, and Krishna K. Govender. "Quantum Mechanistic Studies of the Oxidation of Ethylene by Rhenium Oxo Complexes." Journal of Chemistry 2021 (August 21, 2021): 1–11. http://dx.doi.org/10.1155/2021/7931956.
Abstract:
Transition-metal-mediated oxygen transfer reactions are of importance in both industry and academia; thus, a series of rhenium oxo complexes of the type ReO3L (L = O−, Cl−, F−, OH−, Br−, I−) and their effects as oxidation catalysts on ethylene have been studied. The activation and reaction energies for the addition pathways involving multiple spin states (singlet and triplet) have been computed. In all cases, structures on the singlet potential energy surfaces showed higher stability compared to their counterparts on the triplet potential energy surfaces (PESs). Frontier Molecular Orbital calculations show electrons flow from the HOMO of ethylene to the LUMO of rhenium for all complexes studied except ReO4− where the reverse case occurs. In the reaction between ReO3L (L = O−, Cl−, F−, OH−, Br−, and I−) and ethylene, the concerted [3 + 2] addition pathway on the singlet PES leading to the formation of dioxylate intermediate is favored over the [2 + 2] addition pathway leading to the formation of a metallaoxetane intermediate and subsequent rearrangement to the dioxylate. The activation and the reaction energies for the formation of the dioxylate on the singlet PES for the ligands studied followed the order O− > OH− > I− > F− > Br− > Cl− and O− > OH− > F− > I− > Br− > Cl−, respectively. Furthermore, the activation and the reaction energies for the formation of the metallaoxetane intermediate increase in the order O− > OH− > I− > Br− > Cl− > F− and O− > Br− > I− > Cl− > OH− > F−, respectively. The subsequent rearrangement of the metallaoxetane intermediate to the dioxylate is only feasible in the case of ReO4−. Of all the complexes studied, the best dioxylating catalyst is ReO3Cl (singlet surface) and the best epoxidation catalyst is ReO3F (singlet surface).
17
Woon, Kai Lin, Zhao Xian Chong, Azhar Ariffin, and Chee Seng Chan. "Relating molecular descriptors to frontier orbital energy levels, singlet and triplet excited states of fused tricyclics using machine learning." Journal of Molecular Graphics and Modelling 105 (June 2021): 107891. http://dx.doi.org/10.1016/j.jmgm.2021.107891.
18
Suishu, Takaaki, Seiichiro Tsuru, Tetsuro Shimo, and Kenichi Somekawa. "Singlet and triplet photocycloaddition reactions of 2-pyridones with propenoate and 2,4-pentadienotes, and the frontier molecular orbital analysis." Journal of Heterocyclic Chemistry 34, no. 3 (May 1997): 1005–11. http://dx.doi.org/10.1002/jhet.5570340346.
19
Kuznetsov, Aleksey E. "Comparison of P- and As-core-modified porphyrins with the parental porphyrin: a computational study." Pure and Applied Chemistry 93, no. 5 (February 8, 2021): 561–70. http://dx.doi.org/10.1515/pac-2020-1105.
Abstract:
Abstract The first comparative DFT (B3LYP/6-31G*) study of the Zn-porphyrin and its two derivatives, ZnP(P)4 and ZnP(As)4, is reported. For all three species studied, ZnP, ZnP(P)4 and ZnP(As)4, the singlet was calculated to be the lowest-energy structure and singlet-triplet gap was found to decrease from ca. 41—42 kcal/mol for N to ca. 17—18 kcal/mol for P and to ca. 10 kcal/mol for As. Both ZnP(P)4 and ZnP(As)4 were calculated to attain very pronounced bowl-like shapes. The frontier molecular orbitals (MOs) of the core-modified porphyrins are quite similar to the ZnP frontier MOs. For the HOMO-2 of the core-modified porphyrins due to the ZnP(P)4/ZnP(As)4 bowl-like shapes we might suppose the existence of “internal” electron delocalization inside the ZnP(P)4/ZnP(As)4 “bowls”. Noticeable reduction of the HOMO/LUMO gaps was calculated for ZnP(P)4 and ZnP(As)4, by ca. 1.10 and 1.47 eV, respectively, compared to ZnP. The core-modification of porphyrins by P and especially by As was found to result in significant decrease of the charge on Zn-centers, by ca. 0.61—0.67e for P and by ca. 0.69—0.76e for As. Charges on P- and As-centers were computed to have large positive values, ca. 0.41—0.45e and ca. 0.43—0.47e, for P and As, respectively, compared to significant negative values, ca. −0.65 to −0.66e for N. The porphyrin core-modification by heavier N congeners, P and As, can noticeably modify the structures, electronic, and optical properties of porphyrins, thus affecting their reactivity and potential applications.
20
Xiang, Yunjie, Jie Zhang, and Shaohui Zheng. "Designing Potential Donor Materials Based on DRCN5T with Halogen Substitutions: A DFT/TDDFT Study." International Journal of Molecular Sciences 22, no. 24 (December 16, 2021): 13498. http://dx.doi.org/10.3390/ijms222413498.
Abstract:
Experimental researchers have found that the organic solar cell (OSC) based on DRCN5T (an oligothiophene) possesses excellent power conversion efficiency (PCE) of 10.1%. However, to date, there have been few studies about halogenation of DRCN5T, and its effects on photovoltaic properties of halogenated DRCN5T are still not clear. In the present work, we first perform benchmark calculations and effectively reproduce experimental results. Then, eight halogenated DRCN5T molecules are designed and investigated theoretically by using density functional theory (DFT) and time-dependent DFT. The dipole moments, frontier molecular orbital energies, absorption spectra, exciton binding energy (Eb), singlet–triplet energy gap (ΔEST), and electrostatic potential (ESP) of these molecules, and the estimated open circuit voltages (VOCs) of the OSCs with PC71BM as acceptor are presented. We find that (1) generally, halogen substitutions would increase VOC; (2) Eb rises with more fluorine substitutions, but for Cl and Br substitutions, Eb increases firstly and then drops; (3) ΔEST keeps increasing with more halogen substitutions; (4) except for Br substitutions, the averaged ESP arises along with more halogen substitutions; (5) the absorption strength of UV–Vis spectra of DRCN5T2F, DRCN5T4F, DRCN5T6F, and DRCN5T2Cl in the visible region is enhanced with respect to DRCN5T. Based on these results, overall, DRCN5T2Cl, DRCN5T4F, and DRCN5T6F may be promising donors.
21
SUISHU, T., S. TSURU, T. SHIMO, and K. SOMEKAWA. "ChemInform Abstract: Singlet and Triplet Photocycloaddition Reactions of 2-Pyridones with Propenoate and 2,4-Pentadienoates, and the Frontier Molecular Orbital Analysis." ChemInform 28, no. 44 (August 3, 2010): no. http://dx.doi.org/10.1002/chin.199744055.
22
ZHANG, XIAOYU, WEIPING ZHANG, and FANKAI MENG. "TIME-DEPENDENT DENSITY FUNCTIONAL THEORY STUDY ON DYNAMICS OF HYDROGEN BONDING IN EXCITED STATES OF TRANS-ACETANILIDE IN METHANOL SOLVENT." Journal of Theoretical and Computational Chemistry 11, no. 02 (April 2012): 421–35. http://dx.doi.org/10.1142/s0219633612500290.
Abstract:
The hydrogen-bonding dynamics in both singlet and triplet excited states of the trans-acetanilide ( AA ) in methanol ( MeOH ) solvent was investigated using the time-dependent density functional theory (TDDFT) method. Geometric optimizations of the hydrogen-bonded AA–MeOH complexes considered here as well as the isolated AA and MeOH molecules were performed using density functional theory (DFT) method. At the same time, the TDDFT method was performed to calculate the electronic transition energies and corresponding oscillation strengths of all the compounds in the low-lying electronically excited states. In this study, only the intermolecular hydrogen bonds C=O⋯H–O and N–H⋯O–H can be formed. A theoretical forecast that changes of hydrogen bonds in the low-lying electronic excited states was proposed. We discussed not only ground-state geometric structures and electronic excitation energies but also frontier molecular orbitals and electron density transition. The intermolecular hydrogen bonds between AA and MeOH molecules play an important role in the geometric structures and electronic excitation energies. Zhao et al. have put forward the relationship between the electronic spectra and hydrogen bonding dynamics for the first time. According to Zhao's rule, a redshift of the relevant electronic spectra will appear if hydrogen bond is strengthened, while the hydrogen bond weakening can make an electronic spectra shift to blue.
23
Bichan, Nataliya G., Ekaterina N. Ovchenkova, Varvara A. Mozgova, Alexander A. Ksenofontov, Nadezhda O. Kudryakova, Ivan V. Shelaev, Fedor E. Gostev, and Tatyana N. Lomova. "Donor–Acceptor Complexes of (5,10,15,20-Tetra(4-methylphenyl)porphyrinato)cobalt(II) with Fullerenes C60: Self-Assembly, Spectral, Electrochemical and Photophysical Properties." Molecules 27, no. 24 (December 14, 2022): 8900. http://dx.doi.org/10.3390/molecules27248900.
Abstract:
The noncovalent interactions of (5,10,15,20-tetra(4-methylphenyl)porphinato)cobalt(II) (CoTTP) with C60 and 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero[60]pyrrolidine (PyC60) were studied in toluene using absorption and fluorescence titration methods. The self-assembly in the 2:1 complexes (the triads) (C60)2CoTTP and (PyC60)2CoTTP was established. The bonding constants for (C60)2CoTTP and (PyC60)2CoTTP are defined to be (3.47 ± 0.69) × 109 and (1.47 ± 0.28) × 1010 M−2, respectively. 1H NMR, IR spectroscopy, thermogravimetric analysis and cyclic voltammetry data have provided very good support in favor of efficient complex formation in the ground state between fullerenes and CoTTP. PyC60/C60 fluorescence quenching in the PyC60/C60–CoTTP systems was studied and the fluorescence lifetime with various CoTTP additions was determined. The singlet oxygen quantum yield was determined for PyC60 and the intensity decrease in the 1O2 phosphorescence for C60 and PyC60 with the CoTTP addition leading to the low efficiency of intercombination conversion for the formation of the 3C60* triplet excited state was found. Using femtosecond transient absorption measurements in toluene, the photoinduced electron transfer from the CoTTP in the excited singlet state to fullerene moiety was established. Quantum chemical calculations were used for the determination of molecular structure, stability and the HOMO/LUMO energy levels of the triads as well as to predict the localization of frontier orbitals in the triads.
24
Tang, Chunmei, Weihua Zhu, and Kaiming Deng. "Density functional energetics and frontier orbitals analysis for the derivatives of the nonclassical triplet-pentagon-fusion fullerene C64X (X=Si and Ge)." Journal of Molecular Structure: THEOCHEM 950, no. 1-3 (June 2010): 36–40. http://dx.doi.org/10.1016/j.theochem.2010.03.019.
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Ji, Yan-Lin, and Quan-Song Li. "Boron-containing thermally activated delayed blue fluorescence materials via donor tuning: A theoretical study." Chinese Journal of Chemical Physics 35, no. 3 (June 2022): 499–508. http://dx.doi.org/10.1063/1674-0068/cjcp2203039.
Abstract:
Based on the boron-containing thermally activated delayed fluorescence (TADF) compound p-AC (AC: acridine) 5,9-dioxa-13b-boranaphtho [3,2,1-de] anthracene (a), a series of new TADF molecules b1−b4 were designed via adding two nitrogen atoms at the AC donor part. Density functional theory and time-dependent density functional theory calculations were performed on the frontier orbital energy levels, emission spectra, singlet-triplet states energy gaps (Δ EST), reverse intersystem crossing (RISC) rate constant ( kRISC) for compounds a and b1−b4. Our calculation results show that the maximum emission wavelengths of b1−b4 are significantly blue-shifted by 47−125 nm compared with that of a. Molecules b1 and b3 exhibit dark-blue emission, while molecules b2 and b4 display light-blue emission, indicating that these four derivatives could be potential organic light-emitting diode (OLED) candidates with blue-light emitting. Moreover, we found the RISC processes in a, b2, and b4 can occur not only from T1 state to S1 state, but also from T2 state to S1 state significantly, while the RISC processes in b1 and b3 mainly take place via the T2→S1 hot exciton way. Importantly, the T1→S1 kRISC values of b2 and b4 are predicted to be two to three times of that of a, indicating enhanced TADF property. Our results not only provide two promising boron-based TADF candidates (b2 and b4), but also offer useful theoretical basis for the design of blue OLED materials.
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Till, Holger, Georg Singer, Christoph Castellani, and Berndt Urlesberger. "Loop Ileostomy in Europe's Tiniest Male Newborn for Meconium-Related Ileus." European Journal of Pediatric Surgery Reports 09, no. 01 (January 2021): e17-e19. http://dx.doi.org/10.1055/s-0040-1721406.
Abstract:
AbstractWith the advances of neonatology, the survival rate for “live-born periviable fetuses” weighing < 300 g, a subgroup of extremely low birth weight (BW) infants, has improved over the past 10 years. Meconium-related ileus (MRI) represents an early postnatal hazard, and, if medical evacuation fails, a surgical challenge in such immature babies. We report the interdisciplinary management of surgically treated MRI in a newborn with a BW of 273 g. According to the worldwide database held by the University of Iowa, he is registered as the tiniest male newborn in Europe. The boy was born in the 25th gestational week by cesarean section after a triplet pregnancy with twin–twin transfusion syndrome, him being the donor. He had a BW of 273 g, whereas his brothers had a BW of 740 g and 722 g. Cardiopulmonary stabilization and ventilation were successful. He developed MRI unresponsive to medical treatment. On day 14 of life, a minilaparotomy was performed in the right lower quadrant to externalize a loop of the distal ileum in a no-touch technique. Despite the small diameter of only 2 mm, a standard loop ileostomy could be fashioned. There were no intra- or postoperative abdominal complications. Bowel function and weight gain were adequate and the ileostomy was closed electively 5 months later at a body weight of 3.5 kg.In summary, minilaparotomy and loop ileostomy placement were effective to treat surgical MRI in Europe's tiniest male newborn. With the advances of neonatology, pediatric surgery reaches new frontiers as well.
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Shee, James, John L. Weber, David R. Reichman, Richard A. Friesner, and Shiwei Zhang. "On the potentially transformative role of auxiliary-field quantum Monte Carlo in quantum chemistry: A highly accurate method for transition metals and beyond." Journal of Chemical Physics 158, no. 14 (April 14, 2023): 140901. http://dx.doi.org/10.1063/5.0134009.
Abstract:
Approximate solutions to the ab initio electronic structure problem have been a focus of theoretical and computational chemistry research for much of the past century, with the goal of predicting relevant energy differences to within “chemical accuracy” (1 kcal/mol). For small organic molecules, or in general, for weakly correlated main group chemistry, a hierarchy of single-reference wave function methods has been rigorously established, spanning perturbation theory and the coupled cluster (CC) formalism. For these systems, CC with singles, doubles, and perturbative triples is known to achieve chemical accuracy, albeit at [Formula: see text]( N7) computational cost. In addition, a hierarchy of density functional approximations of increasing formal sophistication, known as Jacob’s ladder, has been shown to systematically reduce average errors over large datasets representing weakly correlated chemistry. However, the accuracy of such computational models is less clear in the increasingly important frontiers of chemical space including transition metals and f-block compounds, in which strong correlation can play an important role in reactivity. A stochastic method, phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC), has been shown to be capable of producing chemically accurate predictions even for challenging molecular systems beyond the main group, with relatively low [Formula: see text]( N3 − N4) cost and near-perfect parallel efficiency. Herein, we present our perspectives on the past, present, and future of the ph-AFQMC method. We focus on its potential in transition metal quantum chemistry to be a highly accurate, systematically improvable method that can reliably probe strongly correlated systems in biology and chemical catalysis and provide reference thermochemical values (for future development of density functionals or interatomic potentials) when experiments are either noisy or absent. Finally, we discuss the present limitations of the method and where we expect near-term development to be most fruitful.
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Santos-Magalhães, N. S., E. A. Bouton, and H. M. De Oliveira. "HOW TO REPRESENT THE GENETIC CODE?" Revista de Ensino de Bioquímica 2, no. 2 (May 15, 2004): 13. http://dx.doi.org/10.16923/reb.v2i2.145.
Abstract:
The advent of molecular genetic comprises a true revolution of far-reaching consequences for human-kind, which evolved into a specialized branch of the modern-day Biochemistry. The analysis of specicgenomic information are gaining wide-ranging interest because of their signicance to the early diag-nosis of disease, and the discovery of modern drugs. In order to take advantage of a wide assortmentof signal processing (SP) algorithms, the primary step of modern genomic SP involves convertingsymbolic-DNA sequences into complex-valued signals. How to represent the genetic code? Despitebeing extensively known, the DNA mapping into proteins is one of the relevant discoveries of genetics.The genetic code (GC) is revisited in this work, addressing other descriptions for it, which can beworthy for genomic SP. Three original representations are discussed. The inner-to-outer map buildson the unbalanced role of nucleotides of a codon. A two-dimensional-Gray genetic representationis oered as a structured map that can help interpreting DNA spectrograms or scalograms. Theseare among the powerful visual tools for genome analysis, which depends on the choice of the geneticmapping. Finally, the world-chart for the GC is investigated. Evoking the cyclic structure of thegenetic mapping, it can be folded joining the left-right borders, and the top-bottom frontiers. As aresult, the GC can be drawn on the surface of a sphere resembling a world-map. Eight parallels oflatitude are required (four in each hemisphere) as well as four meridians of longitude associated tofour corresponding anti-meridians. The tropic circles have 11.25o, 33.75o, 56.25o, and 78.5o (Northand South). Starting from an arbitrary Greenwich meridian, the meridians of longitude can be plottedat 22.5o, 67.5o, 112.5o, and 157.5o (East and West). Each triplet is assigned to a single point on thesurface that we named Nirenberg-Kohamas Earth. Despite being valuable, usual representations forthe GC can be replaced by the handy descriptions oered in this work. These alternative maps arealso particularly useful for educational purposes, giving a much rich interpretation and visualizationthan a simple look-up table.
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Acharya, Swagata, Dimitar Pashov, Cédric Weber, Hyowon Park, Lorenzo Sponza, and Mark Van Schilfgaarde. "Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$." Communications Physics 2, no. 1 (December 2019). http://dx.doi.org/10.1038/s42005-019-0254-1.
Abstract:
AbstractUnconventional superconductivity in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$Sr2RuO4 has been intensively studied for decades. However, the nature of pairing continues to be widely debated. Here we develop a detailed ab initio theory, coupling quasiparticle self-consistent GW approximation with dynamical mean field theory (DMFT), including both local and non-local correlations to address the subtle interplay among spin, charge and orbital degrees of freedom. We report that the superconducting instability has multiple triplet and singlet components. In the unstrained case the triplet eigenvalues are larger than the singlets. Under uniaxial strain, the triplet eigenvalues drop and the singlet components increase. This is concomitant with our observation of spin and charge fluctuations shifting closer to wave-vectors favoring singlet pairing. We identify a complex mechanism where charge fluctuations and spin fluctuations co-operate in the even-parity channel under strain leading to increment in critical temperature (Tc), thus proposing a novel mechanism for pushing the frontier of critical temperature (Tc) in unconventional ‘triplet’ superconductors.
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Monteiro, Ana Shirley, Regivan Santiago, Benjamín Bedregal, Eduardo Palmeira, and Juscelino Araújo. "On retractions and extension of quasi-overlap and quasi-grouping functions defined on bounded lattices." Journal of Intelligent & Fuzzy Systems, November 16, 2023, 1–14. http://dx.doi.org/10.3233/jifs-232805.
Abstract:
Saminger-Platz, Klement, and Mesiar (2008) extended t-norms from a complete sublattice to its respective lattice using the conventional definition of sublattice. In contrast, Palmeira and Bedregal (2012) introduced a more inclusive sublattice definition, via retractions. They expanded various important mathematical operators, including t-norms, t-conorms, fuzzy negations, and automorphisms. They also introduced De Morgan triples (semi-triples) for these operators and provided their extensions in their groundbreaking work. In this paper, we propose a method of extending quasi-overlap functions and quasi-grouping functions defined on bounded sublattices (in a broad sense) to a bounded superlattice. To achieve that, we use the technique proposed by Palmeira and Bedregal. We also define: quasi-overlap (resp. quasi-grouping) functions generated from quasi-grouping (resp. quasi-overlap) functions and frontier fuzzy negations, De Morgan (semi)triples for the classes of quasi-overlap functions, quasi-grouping functions and fuzzy negations, as well as its respective extensions. Finally we study properties of all extensions defined.
31
Pereira, Bianca da Silva Alcantara, Adriana Zilly, Juliana Cristina dos Santos Monteiro, Nayara Gonçalves Barbosa, and Flávia Azevedo Gomes-Sponholz. "Prevalência do aleitamento materno entre povos Indígenas da Tríplice Fronteira: Brasil, Argentina e Paraguai." Revista Brasileira de Saúde Materno Infantil 23 (2023). http://dx.doi.org/10.1590/1806-9304202300000237.
Abstract:
Resumo Objetivos: verificar a prevalência do aleitamento materno e estado nutricional de crianças de origem indígena até dois anos de idade na região de tríplice fronteira: Brasil, Argentina e Paraguai. Métodos: foram analisados dados do Sistema de Vigilância Nutricional e Alimentar Indígena, sendo um estudo transversal e descritivo. A pesquisa foi realizada em 2018, com dados referentes à 2017. Foram incluídos registros de crianças indígenas de zero a dois anos de idade, de ambos os sexos. Os dados foram extraídos do mapa de acompanhamento de crianças indígenas. Foi avaliada a prevalência do aleitamento materno e alimentação complementar. Resultados: a prevalência de aleitamento materno exclusivo em menores de seis meses foi de 93,4% e do aleitamento materno complementado foi de 6,5%. A prevalência do aleitamento materno complementado após seis meses foi de 71,6% e do aleitamento materno exclusivo após seis meses foi de 28,3%. Com relação à classificação de peso para a idade, 80,5% dos registros mostraram crianças com peso adequado para a idade. Em relação aos benefícios sociais, 30,3% das famílias acumulavam dois tipos de benefícios sociais. Conclusões: a prevalência de aleitamento materno exclusivo foi alta e superam prevalência nacional no primeiro semestre de vida, não houve desmame precoce.
32
Ikeda, Akihiko, Yasuhiro H. Matsuda, Keisuke Sato, Yuto Ishii, Hironobu Sawabe, Daisuke Nakamura, Shojiro Takeyama, and Joji Nasu. "Signature of spin-triplet exciton condensations in LaCoO3 at ultrahigh magnetic fields up to 600 T." Nature Communications 14, no. 1 (April 4, 2023). http://dx.doi.org/10.1038/s41467-023-37125-4.
Abstract:
AbstractBose-Einstein condensation of electron-hole pairs, exciton condensation, has been effortfully investigated since predicted 60 years ago. Irrefutable evidence has still been lacking due to experimental difficulties in verifying the condensation of the charge neutral and non-magnetic spin-singlet excitons. Whilst, condensation of spin-triplet excitons is a promising frontier because spin supercurrent and spin-Seebeck effects will be observable. A canonical cobaltite LaCoO3 under very high magnetic fields is a propitious candidate, yet to be verified. Here, we unveil the exotic phase diagram of LaCoO3 up to 600 T generated using the electromagnetic flux compression method and the state-of-the-art magnetostriction gauge. We found the continuous magnetostriction curves and a bending structure, which suggest the emergence of two distinct spin-triplet exciton condensates. By constructing a phenomenological model, we showed that quantum fluctuations of excitons are crucial for the field-induced successive transitions. The spin-triplet exciton condensation in a cobaltite, which is three-dimensional and thermally equilibrated, opens up a novel venue for spintronics technologies with spin-supercurrent such as a spin Josephson junction.
33
Mohd Jamel, Nor Shafiq, Kai Lin Woon, Muhammad Kumayl AbdWahab, Dmytro Volyniuk, Matas Gužauskas, Azzuliani Supangat, Nurdiana Nordina, et al. "Effect of Fluorination on the properties of 9,9'‐(sulfonylbis(4,1‐phenylene))bis(3‐(tert‐butyl)‐6‐fluoro‐9H‐carbazole) as Host for Thermally Activated Delayed Fluorescent Emitters." ChemPhotoChem, May 27, 2024. http://dx.doi.org/10.1002/cptc.202400138.
Abstract:
To enhance organic light emitting diode (OLED) performance, host materials with high triplet energies are crucial for confining excitons, despite increasing driving voltages due to the singlet‐triplet energy gap. We synthesized sulfonylbis(4,1‐phenylene)bis(3,6‐disubstituted‐9H‐carbazole) derivatives as donor‐acceptor‐donor host materials, namely compounds 3, 5 and 7, with varying fluorination levels. These compounds show moderate singlet‐triplet energy splitting and molecular dipole moments, allowing for fine‐tuning of hole‐transport mobilities, deeper frontier orbital energies, and a red shift in singlet emission while maintaining high triplet energy levels. These adjustments impact a range of physical, electronic and optical properties. The materials exhibit exceptional thermal stability, with decomposition starting above 400°C and glass transition temperatures over 130°C. Used with the green TADF emitter DACT‐II, these hosts enable reverse intersystem crossing rates between 7.43 x 104 s‐1 and 1.77 x 105 s‐1. While OLEDs using mCP as a reference host achieve a maximum quantum efficiency of 18.5%, those with host 5 show lower efficiency roll‐off, leading to higher external quantum efficiency at brightness levels above 2000 cd/m2 without colour shift. The reduced roll‐off in devices with host 5 compared to mCP is attributed to effective Förster and Dexter energy transfers to DACT‐II at high currents, enhancing light emission pathways.
34
Deng, Gang-Hua, Jesse B. Brown, Haley Fisher, Zhi-Chao Huang-Fu, Yuqin Qian, Tong Zhang, Avetik Harutyunyan, Hanning Chen, Gugang Chen, and Yi Rao. "The anisotropic nature of singlet fission in single crystalline organic semiconductors." Chemical Physics Reviews 4, no. 4 (December 1, 2023). http://dx.doi.org/10.1063/5.0166062.
Abstract:
The escalating global energy predicament implores for a revolutionary resolution—one that converts sunlight into electricity—holding the key to supreme conversion efficiency. This comprehensive review embarks on the exploration of the principle of generating multiple excitons per absorbed photon, a captivating concept that possesses the potential to redefine the fundamental confines of conversion efficiency, albeit its application remains limited in photovoltaic devices. At the nucleus of this phenomenon are two principal processes: multiple exciton generation (MEG) within quantum-confined environments, and singlet fission (SF) inside molecular crystals. The process of SF, characterized by the cleavage of a single photogenerated singlet exciton into two triplet excitons, holds promise to potentially amplify photon-to-electron conversion efficiency twofold, thereby laying the groundwork to challenge the detailed balance limit of solar cell efficiency. Our discourse primarily dissects the complex nature of SF in crystalline organic semiconductors, laying special emphasis on the anisotropic behavior of SF and the diffusion of the subsequent triplet excitons in single-crystalline polyacene organic semiconductors. We initiate this journey of discovery by elucidating the principles of MEG and SF, tracing their historical genesis, and scrutinizing the anisotropy of SF and the impact of quantum decoherence within the purview of functional mode electron transfer theory. We present an overview of prominent techniques deployed in investigating anisotropic SF in organic semiconductors, including femtosecond transient absorption microscopy and imaging as well as stimulated Raman scattering microscopies, and highlight recent breakthroughs linked with the anisotropic dimensions of Davydov splitting, Herzberg–Teller effects, SF, and triplet transport operations in single-crystalline polyacenes. Through this comprehensive analysis, our objective is to interweave the fundamental principles of anisotropic SF and triplet transport with the current frontiers of scientific discovery, providing inspiration and facilitating future ventures to harness the anisotropic attributes of organic semiconductor crystals in the design of pioneering photovoltaic and photonic devices.
35
Wang, Xiaopeng, Siyu Gao, Aizhu Wang, Bo Wang, and Noa Marom. "Multiple resonance induced thermally activated delayed fluorescence: Effect of chemical modification." Electronic Structure, March 23, 2023. http://dx.doi.org/10.1088/2516-1075/acc70e.
Abstract:
Abstract Thermally activated delayed fluorescence (TADF) is the internal conversion of triplet excitons into singlet excitons via reverse intersystem crossing (RISC). It improves the efficiency of OLEDs by enabling the harvesting of nonradiative triplet excitons. Multiple resonance (MR) induced TADF chromophores exhibit an additional advantage of high color purity due to their rigid conformation. However, owing to the strict design rules there is a limited number of known MR-TADF chromophores. For applications in full-color high-resolution OLED displays, it is desirable to extend the variety of available chromophores and their color range. We computationally explore the effect of chemical modification on the properties of the MR-TADF chromophore quinolino[3,2,1-de]acridine-5,9-dione (QAD). QAD derivatives are evaluated based on several metrics: The formation energy is associated with the ease of synthesis; The spatial distribution of the frontier orbitals indicates whether a compound remains an MR-TADF chromophore or turns into a donor-acceptor TADF chromophore; The change of the singlet excitation energy compared to the parent compound corresponds to the change in color; The energy difference between the lowest singlet and triplet states corresponds to the barrier to RISC; The reorganization energy is associated with the color purity. Based on these metrics, QAD-6CN is predicted to be a promising MR-TADF chromophore with a cyan hue. This demonstrates that computer simulations may aid the design of new MR-TADF chromophores by chemical modification.
36
Homman-Ludiye, Jihane, and James A. Bourne. "The Marmoset: The Next Frontier in Understanding the Development of the Human Brain." ILAR Journal, February 23, 2021. http://dx.doi.org/10.1093/ilar/ilaa028.
Abstract:
Abstract Rodent models, particularly mice, have dominated the field of developmental neuroscience for decades, like they have in most fields of biomedicine research. However, with 80 million years since rodents and primates last shared a common ancestor, the use of mice to model the development of the human brain is not without many shortcomings. The human brain diverges from the mouse brain in many aspects and is comprised of novel structures as well as diversified cellular subtypes. While these newly evolved features have no equivalent in rodents, they are observed in nonhuman primates. Therefore, elucidating the cellular mechanisms underlying the development and maturation of the healthy and diseased human brain can be achieved using less complex nonhuman primates. Historically, macaques were the preferred nonhuman primate model. However, over the past decade, the New World marmoset monkey (Callithrix jacchus) has gained more importance, particularly in the field of neurodevelopment. With its small size, twin or triplet birth, and prosocial behavior, the marmoset is an ideal model to study normal brain development as well as neurodevelopmental disorders, which are often associated with abnormal social behaviors. The growing interest in the marmoset has prompted many comparative studies, all demonstrating that the marmoset brain closely resembles that of the human and is perfectly suited to model human brain development. The marmoset is thus poised to extend its influence in the field of neurodevelopment and will hopefully fill the gaps that the mouse has left in our understanding of how our brain forms and how neurodevelopmental disorders originate.
37
Hamlin, James Jeffrey, Ryan Eagle Baumbach, Kevin Huang, Marc Janoschek, Noravee Kanchanavatee, Diego A. Zocco, and M. Brian Maple. "Evolution of the Magnetic and Superconducting States in UCoGe With Fe and Ni Substitution." MRS Proceedings 1264 (2010). http://dx.doi.org/10.1557/proc-1264-z12-04.
Abstract:
AbstractThe very small number of known ferromagnetic superconductors places the study of such compounds at the frontier of superconductivity research. Recently, UCoGe has emerged as a new member of the class of materials exhibiting coexistence of ferromagnetism and superconductivity (Curie temperature TCurie = 3 K; superconducting critical temperature Ts = 0.8 K). This compound has generated much excitement, in part because it has been proposed that the superconductivity derives from spin triplet pairing mediated by ferromagnetic interactions. Therefore, a key question is how changes in the magnetic state of UCoGe affect the superconducting properties. We have carried out a comprehensive study of the UCo1-xFexGe and UCo1-xNixGe series of compounds across the entire range of composition 0 ≤ x ≤ 1. We report the results of x-ray diffraction, electrical resistivity, and magnetization measurements to elucidate the magnetic and superconducting phase diagram of the U[Fe, Co, Ni]Ge system. Substitution of either Ni or Fe into UCoGe initially results in an increase in the Curie temperature. At higher dopant concentrations (x), the ferromagnetic state crosses over to paramagnetism in UCo1-xFexGe and antiferromagnetism in UCo1-xNixGe.
38
Haseena, Sheik, and Mahesh Kumar Ravva. "Theoretical studies on donor–acceptor based macrocycles for organic solar cell applications." Scientific Reports 12, no. 1 (September 3, 2022). http://dx.doi.org/10.1038/s41598-022-19348-5.
Abstract:
AbstractWe have designed a series of new conjugated donor–acceptor-based macrocyclic molecules using state-of-the-art computational methods. An alternating array of donors and acceptor moieties in these macrocycle molecules are considered to tune the electronic and optical properties. The geometrical, electronic, and optical properties of newly designed macrocyclic molecules are fully explored using various DFT methods. Five conjugated macrocycles of different sizes are designed considering various donor and acceptor units. The selected donor and acceptors, viz., thiophene (PT), benzodithiophene (BDT), dithienobenzodithiophene (DTBDT), diketopyrrolopyrrole (DPP), and benzothiazole (BT), are frequently found in high performing conjugated polymer for different organic electronic applications. To fully assess the potential of these designed macrocyclic derivatives, analyses of frontier molecular orbital energies, excited state energies, energy difference between singlet–triplet states, exciton binding energies, rate constants related to charge transfer at the donor–acceptor interfaces, and electron mobilities have been carried out. We found significant structural and electronic properties changes between cyclic compounds and their linear counterparts. Overall, the cyclic conjugated D–A macrocycles’ promising electronic and optical properties suggest that these molecules can be used to replace linear polymer molecules with cyclic conjugated oligomers.
39
Li, Huiting, Huicai Ren, Jiahui Wang, Di Liu, and Jiuyan Li. "Cyano Decoration of p‐Bridge to Boost Photoluminescence and Electroluminescence Quantum Yields of Triazine/carbazole Based Blue TADF Emitter." Chemistry – A European Journal, November 15, 2023. http://dx.doi.org/10.1002/chem.202303169.
Abstract:
In general, a large donor‐acceptor dihedral angle is required to guarantee sufficient frontier molecular orbitals separation for thermally activated delayed fluorescence (TADF) emitters, which is intrinsically unfavorable for the radiative transition. We present a molecular design method favoring both reverse intersystem crossing (RISC) and radiative transitions even at a moderate D‐A angle. A blue TADF emitter TrzBuCz‐CN was designed with triazine/tert‐butylcarbazole as donor/acceptor and cyano (CN) incorporated on the phenylene bridge. In comparison with the methyl decoration in similar way (TrzBuCz‐Me), CN decoration reduced the D‐A dihedral angle from 70° to 60°, which is intrinsically not favorable for sufficient FMO separation, but unexpectedly reduced the singlet and triplet energy gap (ΔEST) and thus facilitated TADF feature by pulling down the lowest singlet state energy. While the reduced distorsion instead improved the HOMO‐LUMO overlap and boosted the fluorescence quantum yield from 41% to 94%. The blue organic light‐emitting diode of TrzBuCz‐CN exhibited an external quantum efficiency of 13.7% with emission peak at 466 nm, greatly superior to 6.0% of TrzBuCz‐Me. The result provides a feasible design strategy to facilitate both RISC and radiation processes by CN decoration of the linking bridge of TADF emitters.
40
Goings, Joshua J., Alec White, Joonho Lee, Christofer S. Tautermann, Matthias Degroote, Craig Gidney, Toru Shiozaki, Ryan Babbush, and Nicholas C. Rubin. "Reliably assessing the electronic structure of cytochrome P450 on today’s classical computers and tomorrow’s quantum computers." Proceedings of the National Academy of Sciences 119, no. 38 (September 12, 2022). http://dx.doi.org/10.1073/pnas.2203533119.
Abstract:
An accurate assessment of how quantum computers can be used for chemical simulation, especially their potential computational advantages, provides important context on how to deploy these future devices. To perform this assessment reliably, quantum resource estimates must be coupled with classical computations attempting to answer relevant chemical questions and to define the classical algorithms simulation frontier. Herein, we explore the quantum computation and classical computation resources required to assess the electronic structure of cytochrome P450 enzymes (CYPs) and thus define a classical–quantum advantage boundary. This is accomplished by analyzing the convergence of density matrix renormalization group plus n -electron valence state perturbation theory (DMRG+NEVPT2) and coupled-cluster singles doubles with noniterative triples [CCSD(T)] calculations for spin gaps in models of the CYP catalytic cycle that indicate multireference character. The quantum resources required to perform phase estimation using qubitized quantum walks are calculated for the same systems. Compilation into the surface code provides runtime estimates to compare directly to DMRG runtimes and to evaluate potential quantum advantage. Both classical and quantum resource estimates suggest that simulation of CYP models at scales large enough to balance dynamic and multiconfigurational electron correlation has the potential to be a quantum advantage problem and emphasizes the important interplay between classical computations and quantum algorithms development for chemical simulation.
41
Tsuji, Takayuki, Satoru Matsuda, Masashi Takeuchi, Hirofumi Kawakubo, and Yuko Kitagawa. "Updates of perioperative multidisciplinary treatment for surgically resectable esophageal cancer." Japanese Journal of Clinical Oncology, June 6, 2023. http://dx.doi.org/10.1093/jjco/hyad051.
Abstract:
Abstract Esophageal cancer has one of the poorest prognoses among all cancer types, due to the propensity for an early spread through the lymphatics and the difficulty to perform surgical treatment. To improve the prognosis, the management of esophageal cancer has been developed through the conduct of several clinical trials worldwide. In western societies, neoadjuvant chemoradiotherapy has been established as the standard treatment approach, as indicated by the results of the CROSS trial. Recently, the Japanese JCOG1109 trial demonstrated the significant improvement of survival by neoadjuvant triplet chemotherapy. As an adjuvant treatment, an immune checkpoint inhibitor has shown promising results in the CheckMate-577 trial. Including adjuvant S-1 mono therapy as another option, a randomised control phase III study will determine the ideal treatment for surgically resectable esophageal cancer. Furthermore, the efficacy and safety of neoadjuvant cisplatin +5-fluorouracil or DCF plus nivolumab are examined in the JCOG1804E (FRONTiER) study. In addition to definitive chemoradiation therapy, the SANO trial is examining the safety and efficacy of active surveillance after neoadjuvant chemoradiotherapy, which might give us the choice to adopt organ preservation approach. The development of treatment has progressed dramatically with the advent of immunotherapy. Considering the biomarkers to predict the treatment response and prognosis, individualised multidisciplinary treatment strategies should be established for esophageal cancer patients.
42
Ye, Zeyuan, Han Wu, Yulin Xu, Tao Hua, Guohao Chen, Zhanxiang Chen, Xiaojun Yin, et al. "Deep‐Blue Narrowband Hetero[6]helicenes Showing Circularly Polarized Thermally Activated Delayed Fluorescence Toward High‐Performance OLEDs." Advanced Materials, November 14, 2023. http://dx.doi.org/10.1002/adma.202308314.
Abstract:
AbstractHelicenes exhibit substantial potential as circularly polarized luminescence (CPL) active molecules. However, their application in circularly polarized organic light‐emitting diodes (CP‐OLEDs) is typically hindered by the challenge of integrating both high color purity and efficient triplet‐harvesting capability, particularly in the blue spectral region. Herein, we introduce a series of hetero[6]helicene‐based emitters that are strategically engineered through the helical extension of a deep‐blue double‐boron‐based multiple resonance thermally activated delayed fluorescence (MR‐TADF) motif. Importantly, the helical extension does not cause apparent structural deformation or perturb frontier molecular orbitals, thus preserving the deep‐blue emission and MR‐TADF characteristics of the parent molecule. This approach also leads to reduced reorganization energy, resulting in emitters with narrower linewidth and higher photoluminescence quantum yield. Furthermore, the helical motif enhances the racemization barrier and leads to improved CPL performance with luminescence dissymmetry factor values up to 1.5 × 10−3. Exploiting these merits, devices incorporating the chiral dopants demonstrate deep‐blue emission within the Broadcast Service Television 2020 color‐gamut range, record external quantum efficiencies (EQEs) up to 29.3%, and distinctive circularly polarized electroluminescence (CPEL) signals. Overall, our findings underscore the helical extension as a promising strategy for designing narrowband chiroptical materials and advancing high‐definition displays.This article is protected by copyright. All rights reserved
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毕翔宇, 黄俊伟, 秦峰, 邱彩玉, and 袁洪涛. "Superconducting Quantum Oscillation Phenomena in Low-Dimensional Superconductors." Acta Physica Sinica, 2022, 0. http://dx.doi.org/10.7498/aps.71.20212289.
Abstract:
Low-dimensional superconductor serves as an excellent platform for investigating emergent superconducting quantum oscillation phenomena. The low-dimensional nature of these materials, originating from the finite size which is comparable with the superconducting coherence length, indicates that the corresponding physical properties will be constrained by quantum confinement effects. Importantly, some of the frontiers and hot issues in low-dimensional superconductors, including the anomalous metal state during the superconductor-insulator transition, spin-triplet pairing mechanism in superconductors, thermal-excited and electrical current-excited vortex motion dynamics in superconductors, and the “charge-vortex duality” in quantum dot materials and superconducting nanowires, are strongly correlated to the superconducting quantum oscillation effects. In recent years, all the above-mentioned topics have achieved breakthroughs based on the studies of superconducting quantum oscillation effects in low-dimensional superconductors. Generally, the periodicity and amplitude of the oscillation can clearly demonstrate the relation between the geometric structure of superconductors and various superconducting mechanisms. In particular, superconducting quantum oscillation phenomena are always correlated with the quantization of magnetic fluxoid and their dynamics, the pairing mechanism of superconducting electrons, and the excitation and fluctuation of superconducting systems. In this review article, three types of typical superconducting quantum oscillation effects observed in low-dimensional superconductors will be discussed from the aspects of research methods, theoretical expectations, and experimental results. a) The Little-Parks effect is the superconducting version of the Aharonov-Bohm effect, whose phase, amplitude and period are all helpful for the study of superconductivity: the phase directly reflects the pairing mechanism in superconductors, the amplitude can be used for investigating the anomalous metal state during the transition from superconductor to insulator, and the period provides information of the sample geometry. b) The vortex motion effect is excited by thermal or electrical current fluctuation, and the corresponding oscillation phenomena show distinct temperature-dependent amplitude compared with the Little-Parks effect. c) The Weber blockade effect originates from the magnetic flux moving across the superconducting nanowire, and such an effect provides unique non-monotonic critical current I_C under magnetic field in I-V characteristics for superconductor-based field-effect transistors. The prospects of the above-mentioned quantum oscillation effects of the low-dimensional superconductors for application are also discussed at the end of this review, including quantum computing, device physics and low-temperature physics.