Ultrafast Decay Dynamics of the 21ππ* Electronic State of N-Methyl-2-pyridone.

The ultrafast decay dynamics of N-methyl-2-pyridone upon excitation in the near-ultraviolet range of 261.5-227.9 nm is investigated using the femtosecond time-resolved photoelectron spectroscopy method. Irradiation at 261.5 nm prepares N-methyl-2-pyridone molecules with high vibrational levels in the 11ππ* state. The radiation-less decay to the ground state via internal conversion is suggested to be the dominant channel for the 11ππ* state with large vibrational excess energy, which is revealed by a lifetime of 1.6 ± 0.2 ps. As the pump wavelength decreases, we found that irradiation at 238.5 and 227.9 nm results in the population of the 21ππ* state. This is in agreement with the assignment of the vapor-phase UV absorption bands of N-methyl-2-pyridone. On the basis of the detailed analysis of our measured time-resolved photoelectron spectra at all pump wavelengths, we conclude that the 21ππ* state has an ultrashort lifetime of 50 ± 10 fs. In addition, the S1(11ππ*) state is subsequently populated via internal conversion and decays over a lifetime of 680-620 fs. The most probable whole deactivation pathway of the 21ππ* state is discussed. This experimental study provides new insights into the excitation energy-dependent decay dynamics of electronically excited N-methyl-2-pyridone.

Insights into ultrafast decay dynamics of electronically excited pyridine-N-oxide.

The ultrafast decay dynamics of pyridine-N-oxide upon excitation in the near-ultraviolet range of 340.2-217.6 nm is investigated using the femtosecond time-resolved photoelectron imaging technique. The time-resolved photoelectron spectra and photoelectron angular distributions at all pump wavelengths are carefully analyzed and the following view is derived: at the longest pump wavelengths (340.2 and 325.6 nm), pyridine-N-oxide is excited to the S1(1ππ*) state with different vibrational levels. The depopulation rate of the S1 state shows a marked dependence on vibrational energy and mode, and the lifetime is in the range of 1.4-160 ps. At 289.8 and 280.5 nm, both the second 1ππ* state and the S1 state are initially prepared. The former has an extremely short lifetime of ∼60 fs, which indicates that the ultrafast deactivation pathway such as a rapid internal conversion to one close-lying state is its dominant decay channel, while the latter is at high levels of vibrational excitation and decays within the range of 380-520 fs. At the shortest pump wavelengths (227.3 and 217.6 nm), another excited state of Rydberg character is mostly excited. We assign this state to the 3s Rydberg state which has a lifetime of 0.55-2.2 ps. This study provides a comprehensive picture of the ultrafast excited-state decay dynamics of the photoexcited pyridine-N-oxide molecule.

α-Alkylation of ketones with primary alcohols by an active non-noble metal Cu/CuOx catalyst.

Development of convenient and effective heterogeneous non-noble metal catalysts for α-alkylation of ketones with alcohols is challenging in heterogeneous catalysis. Here, we report active non-noble metal Cu/CuOx catalysts for the construction of C-C bonds by the α-alkylation of ketones with alcohols through the borrowing hydrogen methodology. The optimal Cu/CuOx-250 catalyst exhibits good catalytic performance in the reactions to give the corresponding products in 50-96% yields. The Cu/CuOx catalysts are characterized by different analysis techniques such as XRD, TEM, XPS, H2-TPR, BET, and ICP. Moreover, the catalyst can be reused at least for five successive cycles without significant loss of activity. The present study provides meaningful insights into the development of non-noble metal heterogeneous catalysts for α-alkylation of ketones with alcohols.

Auranofin inhibits the occurrence of colorectal cancer by promoting mTOR-dependent autophagy and inhibiting epithelial-mesenchymal transformation.

Colorectal cancer (CRC) is one of the world's most common and deadly cancers. According to GLOBOCAN2020's global incidence rate and mortality estimates, CRC is the third main cause of cancer and the second leading cause of cancer-related deaths worldwide. The US Food and Drug Administration has approved auranofin for the treatment of rheumatoid arthritis. It is a gold-containing chemical that inhibits thioredoxin reductase. Auranofin has a number of biological activities, including anticancer activity, although it has not been researched extensively in CRC, and the mechanism of action on CRC cells is still unknown. The goal of this research was to see how Auranofin affected CRC cells in vivo and in vitro . The two chemical libraries were tested for drugs that make CRC cells more responsive. The CCK-8 technique was used to determine the cell survival rate. The invasion, migration, and proliferation of cells were assessed using a transwell test and a colony cloning experiment. An electron microscope was used to observe autophagosome formation. Western blotting was also used to determine the degree of expression of related proteins in cells. Auranofin's tumor-suppressing properties were further tested in a xenograft tumor model of human SW620 CRC cells. Auranofin dramatically reduced the occurrence of CRC by decreasing the proliferation, migration, and invasion of CRC cells, according to our findings. Through a mTOR-dependent mechanism, auranofin inhibits the epithelial-mesenchymal transition (EMT) and induces autophagy in CRC cells. Finally, in-vivo tests revealed that auranofin suppressed tumor growth in xenograft mice while causing no harm. In summary, auranofin suppresses CRC cell growth, invasion, and migration. Auranofin inhibits the occurrence and progression of CRC by decreasing EMT and inducing autophagy in CRC cells via a mTOR-dependent mechanism. These findings suggest that auranofin could be a potential chemotherapeutic medication for the treatment of human CRC.

Excitation Energy-Dependent Decay Dynamics of the S1 State of N-Methyl-2-pyridone.

The UV-induced decay dynamics of N-methyl-2-pyridone is investigated using a femtosecond time-resolved photoelectron spectroscopy method. Irradiation in the wavelength range of 339.3-258.9 nm prepares N-methyl-2-pyridone molecules with very different vibrational levels of the S1(11ππ*) state. For v' = 0 (origin) and a few low-energy vibrational levels slightly above the S1 state origin, the radiative decay channel is in operation for some specific vibrations. This is revealed by the excited-state lifetime of ≫1 ns. In addition, some other nearby S1 vibronic states have a much shorter lifetime in the range of several picoseconds to a few tens of picoseconds, indicating that the radiation-less decay to the ground state (S0) via internal conversion is the dominant channel for them. As the pump wavelength slightly decreases, the radiative decay is suddenly not important at all, and the deactivation rate of the S1 state becomes faster. At shorter pump wavelengths, the lifetime of highly excited vibrational states of the S1 state further decreases with the increase in the vibrational excess energy. This study provides quantitative information about the excitation energy-dependent decay dynamics of the S1 state of N-methyl-2-pyridone. Methyl substitution effects on the excited-state dynamics of 2-pyridone are also discussed.

RIG-I-like receptors: Molecular mechanism of activation and signaling.

During RNA viral infection, RIG-I-like receptors (RLRs) recognize the intracellular pathogenic RNA species derived from viral replication and activate antiviral innate immune response by stimulating type 1 interferon expression. Three RLR members, namely, RIG-I, MDA5, and LGP2 are homologous and belong to a subgroup of superfamily 2 Helicase/ATPase that is preferably activated by double-stranded RNA. RLRs are significantly different in gene architecture, RNA ligand preference, activation, and molecular functions. As switchable macromolecular sensors, RLRs' activities are tightly regulated by RNA ligands, ATP, posttranslational modifications, and cellular cofactors. We provide a comprehensive review of the structure and function of the RLRs and summarize the molecular understanding of sensing and signaling events during the RLR activation process. The key roles RLR signaling play in both anti-infection and immune disease conditions highlight the therapeutic potential in targeting this important molecular pathway.

Excitation wavelength dependent S1-state decay dynamics of 2-aminopyridine and 3-aminopyridine.

The decay dynamics of 2-aminopyridine and 3-aminopyridine excited to the S1 state is investigated using femtosecond time-resolved photoelectron imaging. The lifetime of the S1 state for both molecules shows a rapid decrease with the increase of the vibrational energy. It is shown that, besides intersystem crossing to the lower-lying triplet state of T1, the decay to the ground state (S0) via internal conversion through a conical intersection plays an increasingly important role and becomes dominant for vibrational states well above the S1 state origin. The comparison between 2-aminopyridine and 3-aminopyridine suggests that the intramolecular hydrogen bonding between a hydrogen atom of the NH2 group and the heterocyclic nitrogen atom in 2-aminopyridine effectively hinders the ring deformation at lower vibrational states which is required for the wavepacket to reach the S1/S0 conical intersection, and therefore slows down the S1 to S0 internal conversion.

A Revealing Insight into Gold Cluster Photocatalysts: Visible versus (Vacuum) Ultraviolet Light.

[Au25(PPh3)10(SC2H4Ph)5Cl2]2+ (Au25) supported on TiO2 (P25) exhibited distinct photocatalytic behaviors in the oxidation of amines using visible or ultraviolet light. The activity under visible light (455 nm) was superior to that under ultraviolet light. To gain insight into the origin of this difference, we investigated the photoreaction pathways of Au25 isolated in the gas phase upon irradiation with a pulsed laser with wavelengths of 455, 193, and 154 nm. High-resolution mass spectrometry revealed photon energy-dependent pathways for Au25: dissociation of the PPh3 ligands and PPh3AuCl units at 455 nm, dissociation into small [AunSm]+ ions (n = 3-20; m = 0-4) at 193 nm, and ionization affording the triply charged state at 154 nm. These results were substantiated by density functional theory simulations. On the basis of these results, we proposed that the inferior photocatalytic activity of Au25/P25 under ultraviolet light is mainly due to the poor photostability of Au25.

Vibrational-state dependent decay dynamics of 2-pyridone excited to the S1 electronic state.

The S1(1ππ*) state decay dynamics of 2-pyridone excited around the 000 band origin is investigated using femtosecond time-resolved photoelectron imaging technique. At a pump wavelength of 334.0 nm, the vibrational ground state and a few low energy vibrational states covered by the bandwidth of the pump laser pulses are excited. The lifetimes of the vibrational states show strong dependence on the vibrational energy and mode. A quantum beat between two lowest energy vibrational states is also observed. This study provides quantitative information about the vibrational-state dependent lifetime of the S1 state of 2-pyridone.

Synergy of Pd atoms and oxygen vacancies on In2O3 for methane conversion under visible light.

Methane (CH4) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues regarding both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In2O3 nanorods enables superior photocatalytic CH4 activation by O2. The optimized catalyst reaches ca. 100 µmol h-1 of C1 oxygenates, with a selectivity of primary products (CH3OH and CH3OOH) up to 82.5%. Mechanism investigation elucidates that such superior photocatalysis is induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer, respectively. O2 is proven to be the only oxygen source for CH3OH production, while H2O acts as the promoter for efficient CH4 activation through ·OH production and facilitates product desorption as indicated by DFT modeling. This work thus provides new understandings on simultaneous regulation of both activity and selectivity by the synergy of single atom cocatalysts and oxygen vacancies.

Ultrafast decay dynamics of electronically excited 2-ethylpyrrole.

The excited-state decay dynamics of 2-ethylpyrrole following UV excitation in the wavelength range of 254.8-218.0 nm is investigated in detail using the femtosecond time-resolved photoelectron imaging method. The time-resolved photoelectron spectra and photoelectron angular distributions at all pump wavelengths are carefully analysed and the following picture is derived: at the longest pump wavelengths (254.8, 248.3 and 246.1 nm), 2-ethylpyrrole is excited to the S1(1πσ*) state having a lifetime of about 50 fs. At 248.3, 246.1 and 237.4 nm, another excited state of Rydberg character is excited. The lifetime of this state is ∼570 fs at 237.4 nm and becomes slightly longer at other two pump wavelengths. At the shortest pump wavelengths (230.8 and 218.0 nm), 2-ethylpyrrole is excited to a state which is tentatively assigned to the 11ππ* state, having a lifetime of 75 ± 15 and 48 ± 10 fs for the longer and shorter pump wavelengths, respectively. Internal conversion to the S1(1πσ*) state might be one of the decay mechanisms of the 11ππ* state.

Ultrafast decay dynamics of water molecules excited to electronic D[combining tilde]' and D[combining tilde]'' states: a time-resolved photoelectron spectroscopy study.

The ultrafast decay dynamics of water molecules excited to D[combining tilde]'1B1 and D[combining tilde]''1A2 states is studied by combining two-photon excitation and time-resolved photoelectron imaging methods. The lifetime of the D[combining tilde]'1B1(000) state of H2O (D2O) is determined to be 1.54 ± 0.1 (22.6 ± 1.6) ps, consistent with a previous high-resolution spectroscopic study. The H2O D[combining tilde]''1A2(000) state decays with a lifetime of 4.1 ± 0.2 ps, while in the D2O D[combining tilde]''1A2(000) state, two independent decay pathways are observed, with time constants of 0.55 ± 0.1 and 13 ± 1 ps, respectively. The former is proposed to be associated with a hitherto undocumented D[combining tilde]'' → C[combining tilde] pathway, induced by Coriolis interaction.

Ultrafast excited-state dynamics of 2,5-dimethylpyrrole.

The ultrafast excited-state dynamics of 2,5-dimethylpyrrole following excitation at wavelengths in the range of 265.7-216.7 nm is studied using the time-resolved photoelectron imaging method. It is found that excitation at longer wavelengths (265.7-250.2 nm) results in the population of the S1(1πσ*) state, which decays out of the photoionization window in about 90 fs. At shorter pump wavelengths (242.1-216.7 nm), the assignments are less clear-cut. We tentatively assign the initially photoexcited state(s) to the 1π3p Rydberg state(s) which has lifetimes of 159 ± 20, 125 ± 15, 102 ± 10 and 88 ± 10 fs for the pump wavelengths of 242.1, 238.1, 232.6 and 216.7 nm, respectively. Internal conversion to the S1(1πσ*) state represents at most a minor decay channel. The methyl substitution effects on the decay dynamics of the excited states of pyrrole are also discussed. Methyl substitution on the pyrrole ring seems to enhance the direct internal conversion from the 1π3p Rydberg state to the ground state, while methyl substitution on the N atom has less influence and the internal conversion to the S1(πσ*) state represents a main channel.

An accidental resonance mediated predissociation pathway of water molecules excited to the electronic C[combining tilde] state.

The predissociation dynamics of water molecules in the electronic C[combining tilde] state were studied using the time-resolved photoelectron imaging method. Both vibrationless and vibrationally excited states in the C[combining tilde] electronic state were studied, with an emphasis on the vibrational excitation effects on the predissociation dynamics of the C[combining tilde] state. Besides the well-known rotationally and non-rotationally mediated predissociation pathways (Proc. Natl. Acad. Sci. U. S. A., 2008, 105, 19148), an accidental resonance mediated predissociation pathway for the first bending mode excited state in the C[combining tilde] electronic state of H2O is revealed, providing an excellent example of competition between non-adiabatic decay pathways involving at least five electronic states.

Ultrafast excited-state dynamics of 2,4-dimethylpyrrole.

The ultrafast excited-state dynamics of 2,4-dimethylpyrrole following excitation at wavelengths in the range of 255.8-199.7 nm are studied using the time-resolved photoelectron imaging method. It is found that excitation at longer wavelengths (255.8, 250.0, 246.0 and 242.0 nm) results in population of the S1(1πσ*) state, which decays out of the photoionization window in less than 30 fs. At 237.7 nm, the second 1πσ* state is excited, which decays in about 130 fs. At shorter pump wavelengths (231.8, 224.8, 217.5 and 199.7 nm), the assignments are less clear-cut. We tentatively assign the initially photoexcited states to the 1π3p Rydberg states, which decay in about 60 fs, with internal conversion to the S1(1πσ*) state as one of the decay channels. The lifetimes of these 1π3p Rydberg states vary little with the pump wavelengths in this wavelength range.

A framework for spatial interaction analysis based on large-scale mobile phone data.

The overall understanding of spatial interaction and the exact knowledge of its dynamic evolution are required in the urban planning and transportation planning. This study aimed to analyze the spatial interaction based on the large-scale mobile phone data. The newly arisen mass dataset required a new methodology which was compatible with its peculiar characteristics. A three-stage framework was proposed in this paper, including data preprocessing, critical activity identification, and spatial interaction measurement. The proposed framework introduced the frequent pattern mining and measured the spatial interaction by the obtained association. A case study of three communities in Shanghai was carried out as verification of proposed method and demonstration of its practical application. The spatial interaction patterns and the representative features proved the rationality of the proposed framework.

The frontal-temporal nerve triangle: a new concept of locating the motor and sensory nerves in upper third of the face rhytidectomy.

BACKGROUND: How to avoid damage to the temporal branch of the facial nerve has long been a central topic of discussion. Recently, damage to the supraorbital nerve, the auriculotemporal nerve, and other branches of the trigeminal nerve divisions has attracted much attention. Focusing on frontal and temporal rhytidectomy, the authors have investigated the course and distribution of the facial nerve branches, the supraorbital nerve, the auriculotemporal nerve, and other branches of trigeminal division. In this article, they present the concept of the frontal-temporal nerve triangle; its contents, vicinity, and clinical significances are discussed. METHODS: An anatomical study was performed using 30 temporal-parietal regions of 10 fixed adult cadavers and five fresh cadavers. A step-by-step dissection from the superficial layer to the deep layer was involved; all the measurement data were analyzed, and the mean and standard deviation were calculated and expressed in centimeters. RESULTS: The frontal-temporal nerve triangle is an approximately triangular area formed by the temporal branch of the facial nerve, the supraorbital nerve, and the auriculotemporal nerve. Together with its contents and vicinal structures, it forms a complicated three-dimensional rather than two-dimensional structure. Anatomical structures closely associated with rhytidectomy are located in or near this area. CONCLUSIONS: Acting as the anatomical body surface landmark for preoperatively locating the temporal branch, the supraorbital nerve, the auriculotemporal nerve, and its related structures, the concept of the frontal-temporal nerve triangle has practical significance in designing incisions and selecting planes of dissection in upper third of the face rhytidectomy.

Using the frontal branch of the superficial temporal artery as a landmark for locating the course of the temporal branch of the facial nerve during rhytidectomy: an anatomical study.

BACKGROUND: Previous studies have proposed that the frontal branch of the superficial temporal artery could be used to determine the course of the temporal branch of the facial nerve; however, these studies have not documented this relationship. The objective of this study was to thoroughly examine the courses of the frontal branch and temporal branch in the temporal region and to describe their relationship in detail. The operating technique used to avoid damaging the temporal branch in the rhytidectomy also is discussed. METHODS: An anatomical study was performed on 30 temporoparietal regions from 10 fixed adult cadavers and five fresh cadavers. Twenty halves of head-vascular-cast specimens also were observed. RESULTS: Depending on whether the bifurcation point of the superficial temporal artery is superior or inferior to the horizontal line of the superior orbital rim, the frontal branch can be classified as having a high-location or low-location type. The temporal branch and its terminal twigs run deeper into the superficial temporal fascia and are inferior to the frontal branch in the high-location type. In the low-location type, one or more terminal twigs of the temporal branch interweave with the frontal branch above the horizontal plane of the upper orbital rim and terminate below the frontal eminence. The temporal branch locates within a triangular area formed by the lower aspect of the zygomatic arch, the frontal branch, and the vertical line where it crosses the highest point of the frontal eminence CONCLUSION: The frontal branch can be the anatomical landmark used to locate and protect the temporal branch during rhytidectomy.