RESUMO
Anion photoelectron spectroscopy and theoretical calculations were used to investigate the structural and bonding properties of WN10-/0. The electron affinity of WN10 is measured to be 1.582 ± 0.030 eV. The frequency of the NîN stretch in WN10 is measured to be 2170 ± 80 cm-1, which is red-shifted with respect to that of the dinitrogen molecule indicating that the NîN bonds are weakened in WN10. The theoretical adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of WN10- obtained by calculations at the CCSD(T)/CBS level agree well with experimental results. The structures of WN10-/0 are C4v symmetric pentacoordinated pyramidal structures with five end-on dinitrogen ligands. Our experiments show that the peak of WN10- is dominant in the mass spectrum of anionic WNn, whereas the mass peak of WN12+ is dominant in the mass spectrum of cationic WNn, implying that the stabilities of WNn clusters are strongly related to their charge states.
RESUMO
The association between cooking fuel and hearing loss still needs more research to clarify, and two longitudinal cohort studies were explored to find if solid fuel use for cooking affected hearing in Chinese adults. The data from Chinese Health and Retirement Longitudinal Survey (CHARLS) and Chinese Longitudinal Healthy Longevity Survey (CLHLS) were analyzed. Participants (older than 18) without hearing loss at baseline and follow-up visits were included, which were divided into clean fuel and solid fuel groups. Hearing loss rate was from follow-up visits (both in year 2011) until the recent one (year 2018 in CHARLS and 2019 in CLHLS). Cox regressions were applied to examine the associations with adjustment for potential confounders. Fixed-effect meta-analysis was used to pool the results. A total of 9049 participants (average age 8.34 ± 9.12 [mean ± SD] years; 4247 [46.93%] males) were included in CHARLS cohort study and 2265 participants (average age, 78.75 ± 9.23 [mean ± SD] years; 1148 [49.32%] males) in CLHLS cohort study. There were 1518 (16.78%) participants in CHARLS cohort and 451 (19.91%) participants in CLHLS cohort who developed hearing loss. The group of using solid fuel for cooking had a higher risk of hearing loss (CHARLS: HR, 1.16; 95% CI 1.03-1.30; CLHLS: HR, 1.43; 95% CI 1.11-1.84) compared with the one of using clean fuel. Pooled hazard ratio showed the incidence of hearing loss in the solid fuel users was 1.17 (1.03, 1.29) times higher than that of clean fuel users. Hearing loss was associated with solid fuel use and older people were at higher risk. It is advised to replace solid fuel by clean fuel that may promote health equity.
Assuntos
Culinária , Perda Auditiva , Humanos , Masculino , Perda Auditiva/epidemiologia , Perda Auditiva/etiologia , Perda Auditiva/induzido quimicamente , Feminino , Idoso , China/epidemiologia , Pessoa de Meia-Idade , Estudos Longitudinais , Estudos de Coortes , Idoso de 80 Anos ou mais , Adulto , Fatores de RiscoRESUMO
Bipyramidal structures featuring planar rings serve as potential building blocks for one-dimensional (1D) nanostructures. Pure Ge atoms typically prefer to form three-dimensional rather than planar structures. Although a few-metal-doped bipyramids with pure Ge planar rings are predicted for constructing Ge-based 1D nanostructures, there is limited knowledge about those with both Ge and doped atoms on the same planar rings. Here, we report a hexagonal bipyramidal Mn3Ge5 cluster containing a Mn3Ge3 six-membered ring with the potential to construct a 1D germanium-based nanostructure. We investigated the structures and properties of Mn3Ge5-/0 using anion photoelectron spectroscopy and theoretical calculations. Mn3Ge5- has a C3v symmetric distorted hexagonal bipyramidal structure, while Mn3Ge5 has a C2v symmetric hexagonal bipyramidal structure. Chemical bonding analyses show that Mn3Ge5- could be considered as a [Mn3]V[Ge5]6- complex. First-principles calculations indicate that Mn3Ge5 may be used to construct a 1D ferrimagnetic [Mn3Ge5]∞ nanostructure.
RESUMO
Sterols have long been associated with diverse fields, such as cancer treatment, drug development, and plant growth; however, their underlying mechanisms and functions remain enigmatic. Here, we unveil a critical role played by a GmNF-YC9-mediated CCAAT-box transcription complex in modulating the steroid metabolism pathway within soybeans. Specifically, this complex directly activates squalene monooxygenase (GmSQE1), which is a rate-limiting enzyme in steroid synthesis. Our findings demonstrate that overexpression of either GmNF-YC9 or GmSQE1 significantly enhances soybean stress tolerance, while the inhibition of SQE weakens this tolerance. Field experiments conducted over two seasons further reveal increased yields per plant in both GmNF-YC9 and GmSQE1 overexpressing plants under drought stress conditions. This enhanced stress tolerance is attributed to the reduction of abiotic stress-induced cell oxidative damage. Transcriptome and metabolome analyses shed light on the upregulation of multiple sterol compounds, including fucosterol and soyasaponin II, in GmNF-YC9 and GmSQE1 overexpressing soybean plants under stress conditions. Intriguingly, the application of soybean steroids, including fucosterol and soyasaponin II, significantly improves drought tolerance in soybean, wheat, foxtail millet, and maize. These findings underscore the pivotal role of soybean steroids in countering oxidative stress in plants and offer a new research strategy for enhancing crop stress tolerance and quality from gene regulation to chemical intervention.
Assuntos
Glycine max , Estresse Fisiológico , Glycine max/genética , Glycine max/fisiologia , Glycine max/metabolismo , Estresse Fisiológico/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas , Esteroides/metabolismo , Secas , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genéticaRESUMO
Ferromagnets constructed from nanometals of atomic precision are important for innovative advances in information storage, energy conversion, and spintronic microdevices. Considerable success has been achieved in designing molecular magnets, which, however, are challenging in preparation and may suffer from drawbacks on the incompatibility of high stability and strong ferromagnetism. Utilizing a state-of-the-art self-developed mass spectrometer and a homemade laser vaporization source, we have achieved a highly efficient preparation of pure iron clusters, and here, we report the finding of a strongly ferromagnetic metal-carbon cluster, Fe12C12-, simply by reacting the Fen- clusters with acetylene in proper conditions. The unique stability of this ferromagnetic Fe12C12- cluster is rooted in a plumb-bob structure pertaining to Jahn-Teller distortion. We classify Fe12C12- as a new member of metallo-carbohedrenes and elucidate its structural stability mechanism as well as its soft-landing deposition and magnetization measurements, providing promise for the exploration of potential applications.
RESUMO
We investigate Ge3n+1O-/0 (n = 1-3) clusters using anion photoelectron spectroscopy and theoretical calculations. The results show that the lowest energy structure of Ge4O- is a bent Cs symmetric trigonal bipyramidal structure, while Ge4O has a C3v symmetric trigonal bipyramidal structure. Ge7O- has two coexisting low-lying isomers, the first one can be viewed as a Ge2O unit interacting with a Ge5 trigonal bipyramid, the second one can be regarded as an O atom interacting with a Ge7 pentagonal bipyramid; whereas Ge7O has a C3v symmetric structure with a Ge atom and an O atom capping a Ge6 trigonal antiprism from the bottom and top, respectively. The structures of Ge10O- and Ge10O can be obtained by adding an O atom to different binding sites of a C3v symmetric Ge10. Chemical bonding analyses of Ge3n+1O (n = 1-3) reveal that the O atom interacts with its neighboring three Ge atoms forming one 4c-2e σ bond and two 4c-2e π bonds in the top Ge3O trigonal pyramid, while the terminal Ge atom forms one 4c-2e σ bond in the bottom Ge4 trigonal pyramid. The large HOMO-LUMO gaps of Ge3n+1O (n = 1-3) indicate that they have good stabilities. Ab initio molecular dynamics simulations suggest that both Ge7O and Ge10O are dynamically stable in general at 300 and 500 K. The current work suggests that the C3v symmetric Ge3 units and the insertion growth pattern may be viable for constructing 1D germanium oxide nanostructures with the chemical formula of Ge3n+1O.
RESUMO
A systematic study of the structures and electronic properties of V2-doped silicon clusters, V2Sin-/0 (n = 7-14), was carried out by anion photoelectron spectroscopic experiments combined with theoretical calculations. According to the experimental spectra of V2Sin- (n = 7-14) clusters, the V2Si12- cluster has the highest vertical detachment energy (VDE) of 3.66 eV, while V2Si7- and V2Si14- clusters have lower VDEs of 2.81 and 2.84 eV, respectively. The most stable structure searches find that two V atoms in the V2Sin- clusters with size n = 7 and 8 are located at the surface, while V2Sin- clusters with n ≥ 9 prefer cage-like structures. Based on the analysis of the structural evolution of V2Sin- (n = 9-14) clusters, it can be clearly seen how the antihexagonal prism with one V encapsulated in the cage is gradually built from n = 9 to 12 and further developed from n = 12 to 14 with the extra silicon atoms located at the surface of the Si12 cage. The molecular orbital and the atoms in molecule analysis of the V2Sin- (n = 7-14) anions demonstrate that the strong V-V bond and the delocalized interaction between the V2 moiety and the Sin ligand play a significant role in stabilizing the cluster structures. A strong linear correlation has been found between the Wiberg bond order of the V-V bond and the electron density at the V-V bond critical points.
RESUMO
The discovery of graphene and its excellent properties inspired the search for more two-dimensional (2D) materials. Understanding the structures and properties of the smallest repeating units as well as crystal 2D materials is helpful for designing 2D materials. As germanium tends to form three-dimensional structures, the preparation of germanium-based 2D nanomaterials is still a challenge. Herein, we report a Ge3O3 cluster with the potential to construct a germanium oxide 2D nanostructure. We conduct a combined anion photoelectron spectroscopy and theoretical study on Ge3O3-/0. The structure of Ge3O3- is a Cs symmetric nonplanar six-membered ring, while that of Ge3O3 is a D3h symmetric planar six-membered ring. Chemical bonding analyses reveal that Ge3O3 exhibits π aromaticity. First-principle results suggest that a buckled honeycomb 2D nanostructure with a wide band gap of 3.14 eV may be produced based on Ge3O3, which is promising in optoelectronic applications especially in blue, violet, and ultraviolet regions.
RESUMO
The study of C2 Al4 -/0 and C2 Al5 -/0 was conducted using anion photoelectron spectroscopy and quantum chemical computations. The present findings reveal that C2 Al4 - has a boat-like structure, with a single C2 unit surrounded by four aluminum atoms. In contrast, the neutral C2 Al4 species adopts a D2h planar structure with two planar tetracoordinate carbon (ptC) units, consistent with previous reports. Furthermore, the global minimum isomer of C2 Al5 - adopts a D3h symmetry, where the C2 unit interacts with five aluminum atoms. It was also found that a lower symmetry structure of C2 Al5 - , where all five aluminum atoms are located on the same side of the C2 unit, albeit slightly higher in energy compared to the D3h structure. These computations show that the D3h structure of C2 Al5 - is highly stable, exhibiting a large HOMO-LUMO gap.
RESUMO
Objective: This study aims to evaluate the association between lower grip strength and mortality hazard. Methods: We selected 10,280 adults aged 45 to 96 years old from the China Health and Retirement Longitudinal Study and used multivariate Cox proportional hazard models to assess the association of grip strength with mortality hazard. In addition, we explored the possibility of a nonlinear relationship using a 4-knot restricted spline regression. Results: We found that elevated grip strength was associated with lower mortality up to a certain threshold. The baseline quartile values of grip strength were 30, 37, and 44 kg for males and 25, 30, and 35 kg for females. After adjusting for confounders, with category 1 as the reference group, the adjusted HRs were 0.58 (0.42-0.79) in males and 0.70 (0.48-0.99) in females (category 4). We also found a linear association between grip strength values and all-cause death risk (males, P = 0.274; females, P = 0.883) using restricted spline regression. For males with a grip strength < 37 kg and females with a grip strength < 30 kg, grip strength and death were negatively associated. Conclusion: Grip strength below a sex-specific threshold is inversely associated with mortality hazard among middle-aged and older Chinese adults with chronic diseases.
Assuntos
Doença Crônica , População do Leste Asiático , Força da Mão , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos LongitudinaisRESUMO
Unlike C≡O, which is common in coordination chemistry and organometallic chemistry, little is known about Si≡O or Ge≡O compounds. Here we report a Ge6O- cluster featuring a Ge≡O triple bond. The structural and chemical bonding properties of Ge6O-/0 are investigated using anion photoelectron spectroscopy and theoretical calculations. Two nearly degenerate isomers have been found for Ge6O-. The lowest-energy structure (6A) can be viewed as an O atom bonding with a tetragonal bipyramidal Ge6. The second one (6B) can be considered as an O atom interacting with a capped trigonal bipyramidal Ge6. Chemical bonding analyses reveal that Ge6O- (6A) can be viewed as a Ge≡O unit interacting with a σ antiaromatic C2v symmetric tetragonal pyramidal Ge53- moiety. Comparisons of the chemical bonding in Ge6O- (6A) with that in Ge5CO- and Ge5MnO- indicate the similar behavior of Ge≡O to C≡O and Mn≡O in its bonding to the Ge53- and Ge54- moieties.
RESUMO
The structures and bonding properties of several lithium polysulfide clusters LiSn-/0 (n = 3-5) and Li2S4-/0 were investigated by size-selected anion photoelectron spectroscopy coupled with quantum chemistry calculations. The vertical detachment energies of LiS3-, LiS4-, and LiS5- were estimated to be 2.17 ± 0.08, 3.30 ± 0.08 and 3.66 ± 0.08 eV, respectively, and that of Li2S4- was estimated to be 3.21 ± 0.08 eV. It is found that LiS3- and LiS3 have planar quadrilateral structures, and LiS4- and LiS4 have distorted five-membered ring structures. LiS5- has a distorted six-membered ring structure while neutral LiS5 has a book-shaped structure. The lowest-lying structure of Li2S4- can be viewed as a S2 unit connecting to the Li-Li edge of a Li2S2 tetrahedron. The lowest-lying structure of neutral Li2S4 can be viewed as a S2 unit connecting to the S atoms of a Li2S2 quadrilateral. The natural population analysis (NPA) and electron localization function (ELF) analyses show that the excess electron of LiSn- is mainly localized over the sulfur chains, especially on the S atoms interacting with Li, thus, the most stable structures of LiSn- can be regarded as a Li+ cation interacting with a Sn2- dianion. The results may be useful for understanding the formation of lithium polysulfides in lithium sulfur batteries.
RESUMO
Bimetallic niobium-doped aluminum clusters, NbAln-/0 (n = 3-12), are investigated through a synergetic combination of size-selected anion photoelectron spectroscopy and theoretical calculations. It is found that the dominant structures of NbAln- anions with n = 3-8 can be described by gradually adding Al atoms to the NbAl3- core. Starting from n = 9, the lowest-energy geometric structures of NbAl9-12- transform into bilayer structures. In particular, NbAl12- has a C3v symmetric structure, which can be viewed as a NbAl6 regular hexagon over a bowl-shaped Al6 structure. More detailed analyses indicate that NbAl9 and NbAl12- possess unusual stability, which may be attributed to their closed-shell electron configurations with superatomic features.
RESUMO
We present joint anion photoelectron spectroscopy and theoretical studies for Mn2Ge6- and Mn2Ge7-. Experimental results show that Mn2Ge6- and Mn2Ge7- have vertical electron detachment energies of 2.58 ± 0.08 and 2.88 ± 0.08 eV, respectively. Both Mn2Ge6- and Mn2Ge6 have Cs symmetric structures with a Mn atom attached to a pentagonal bipyramid MnGe6. Both Mn2Ge7- and Mn2Ge7 have C2v symmetric structures, which can be considered as two Mn2Ge4 tetragonal bipyramids sharing a MnGeMn face. According to chemical bonding analyses, Mn2Ge6 could be considered as a (MnII)(MnGe62-) complex. Theoretical calculations predict that the extension of Mn2Ge7 to Mn2nGe4n+3 may be able to produce a new type of Mn-doped germanium nanostructure.
RESUMO
The structures and chemical bonding of Ge6MnO- are investigated using anion photoelectron spectroscopy and theoretical calculations. The lowest energy structure of Ge6MnO- is found to have a C5v symmetric structure with an O atom attached to a pentagonal bipyramidal MnGe6. Chemical bonding analyses reveal that Ge6MnO- can be considered as a [MnV≡O]3+[Ge64-] complex with two unpaired 3d electrons on Mn. The Ge64- ligand is highly stable in Ge6MnO- and exhibits double aromaticity with 10 delocalized σ electrons and 6 delocalized π electrons. Our calculations show that the Ge64- ligand could also form [CrIV≡O]2+[Ge64-] in Na2Ge6CrO and [FeIV≡O]2+[Ge64-] in Na2Ge6FeO. The results suggest the possibility of designing and synthesizing a series of stable high-valent metal oxide anionic species with the composition [M≡O]n+[Ge64-] in the gas phase or in the salt-stabilized bulk solid materials.
RESUMO
Carbon-doped aluminum cluster anions, AlnC- (n = 6-15), were generated by laser vaporization and investigated by mass-selected anion photoelectron spectroscopy. The geometric structures of AlnC- (n = 6-15) anions were determined by the comparison of theoretical calculations with the experimental results. It is found that the most stable structure of Al6C- is a carbon endohedral triangular prism. The Al7C- anion is a magic cluster with high stability. The structures of Al7-9C- can be viewed as the additional aluminum atoms attached around the triangular prism Al6C-. Two isomers of Al10C- have been detected in the experiments. The most stable one has a planar tetracoordinate carbon structure. The second one derives from Al9C- with the carbon atom located in a pentagonal bipyramid. The Al11C- anion has a bilayer structure composed of one planar tetracoordinate carbon and one aluminum-centered hexagon, in which the major interactions between two layers are multicenter bonds. The structures of Al12-14C- can be viewed as evolving from Al11C- by adding aluminum atoms to interact with the carbon atom. In Al15C-, the carbon atom stays at the surface with a tetracoordinate structure, and an icosahedral Al13 unit can be identified as a part of the geometric structure of Al15C-.
RESUMO
The structural and electronic properties of bimetallic oxide clusters, YCu2On- and YCu2On (n = 2-5), are investigated using anion photoelectron spectroscopy and density functional theory calculations. The experimental vertical detachment energies of YCu2O2-, YCu2O3-, YCu2O4-, and YCu2O5- were measured to be 1.59, 1.76, 3.85, and 3.78 eV, respectively. Vibrationally resolved photoelectron spectra have been obtained for YCu2O2-, with a spacing of 726 ± 80 cm-1 assigned to the Y-O stretching vibrational mode. It is found that YCu2O2- and YCu2O2 have C2v symmetric planar five-membered ring structures. YCu2O3- and YCu2O3 have C2v symmetric planar six-membered ring structures. The most stable structure of YCu2O4- is a quasi-planar structure which can be viewed as one O atom interacting with the Y atom of the YCu2O3 six-membered ring, while the most stable structure of YCu2O4 is a planar seven-membered ring. YCu2O5- and YCu2O5 have nonplanar structures, which can be viewed as an O2 unit interacting with the Y atom of the YCu2O3 six-membered ring. In YCu2O3,4,5-/0, the Y-O and Cu-O bonds are dominant, while the Y-Cu and Cu-Cu interactions are weak.
RESUMO
The structures, chemical bonding, and magnetic properties of MnGe3O-/0 and MnGe4O-/0 are investigated by photoelectron spectroscopy and ab initio calculations. The experimental vertical electron detachment energies of MnGe3O- and MnGe4O- are measured to be 2.06 ± 0.04 and 2.64 ± 0.04 eV, respectively. The structures of MnGe3O-/0 and MnGe4O-/0 can be viewed as evolved from quadrilateral MnGe3 or tetrahedral MnGe3. It is found that both MnGe3O- and MnGe3O have Cs symmetric planar structures with an O atom attached to quadrilateral MnGe3. The structure of MnGe4O- is nonplanar with an O atom and an additional Ge atom attached to tetrahedral MnGe3, while that of MnGe4O is planar with an O atom and an additional Ge atom attached to quadrilateral MnGe3. Chemical bonding analyses reveal the existence of GeâO double bonds in MnGe3O and MnGe4O. Magnetic property analyses suggest that MnGe3O and MnGe4O are ferromagnetic with total spin magnetic moments of 5 µB.
RESUMO
We investigate the structures and properties of Mn2Ge4-/0 and Mn2Ge5-/0 by anion photoelectron spectroscopy and theoretical calculations. The vertical detachment energies (VDEs) of Mn2Ge4- and Mn2Ge5- are measured to be 2.69 eV and 2.49 eV, respectively. It is found that neutral Mn2Ge4 has an approximate quadrilateral bipyramidal structure with C2v symmetry and 11B2 electronic state. Neutral Mn2Ge5 has a pentagonal bipyramidal structure with C2v symmetry and 11B2 electronic state. The 4s-based molecular orbitals of the Mn atoms participate in the chemical bonding with the Ge4 and Ge5 fragments in Mn2Ge4 and Mn2Ge5. In Mn2Ge4, the two Mn atoms interact with the Ge4 moiety via four GeGeMn 3c-2e σ bonds. In Mn2Ge5, the two Mn atoms interact with the Ge5 moiety via one MnGeMn 3c-2e σ bond and four GeMnGe 3c-2e σ bonds. The analysis of magnetic properties reveals that both Mn2Ge4 and Mn2Ge5 exhibit highly ferromagnetic characteristics with a magnetic moment of 10 µB which mainly originated from the Mn atoms. These double Mn atom doped germanium clusters may provide new opportunities to design novel spintronic devices featuring high magnetic moments.
RESUMO
We investigated the structural characteristics and bonding properties of Cr2Sin- (n = 1-12) clusters by using anion photoelectron spectroscopy combined with density functional theory calculations. The experimental and theoretical results reveal that Cr atoms of the most stable structures of Cr2Sin- clusters with n < 8 are located at the surface, while the most stable structures of Cr2Sin- clusters with n ≥ 8 have one Cr encapsulated in the cage consisting of the other Cr atom and the Si atoms. The Cr-Cr interaction in the most stable structures of Cr2Sin- clusters is strong, except that the Cr-Cr interaction in the lowest lying isomer of the Cr2Si5- cluster is weak. The structure of Cr2Si6- can be viewed as the Cr2 surrounded by a chair-shaped silicon six-membered ring with the C2h symmetry. Cr2Si12- has a C6v symmetric antihexagonal prism structure with two Cr atoms located at the center and the surface of the Si12 cage, respectively. The magnetic moments of Cr2Sin- are 1 µB except that the magnetic moment of Cr2Si5- is 9 µB.