Triel Bonds between BH3/C5H4BX and M(MDA)2 (X = H, CN, F, CH3, NH2; M = Ni, Pd, Pt, MDA = Enolated Malondialdehyde) and Group 10 Transition Metal Electron Donors.

A systematic theoretical study was conducted on the triel bonds (TrB) within the BH3∙∙∙M(MDA)2 and C5H4BX∙∙∙M(MDA)2 (M = Ni, Pd, Pt, X = H, CN, F, CH3, NH2, MDA = enolated malondialdehyde) complexes, with BH3 and C5H4BX acting as the electron acceptors and the square-coordinated M(MDA)2 acting as the electron donor. The interaction energies of these systems range between -4.71 and -33.18 kcal/mol. The larger the transition metal center M, the greater the enhancement of the TrB, with σ-hole TrBs found to be stronger than π-hole TrBs. In the σ-hole TrB complex, an electron-withdrawing substituent on the C opposite to the B atom enhances the TrB, while an electron-donating substituent has little effect on the strength of TrB in the Pd and Pt complexes but enhances the TrB in the Ni-containing complexes. The van der Waals interaction plays an important role in stabilizing these binary systems, and its contribution diminishes with increasing M size. The orbital effect within these systems is largely due to charge transfer from the dz2 orbital of M into the empty pz orbital of B.

Altered Fhod3 expression involved in progressive high-frequency hearing loss via dysregulation of actin polymerization stoichiometry in the cuticular plate.

Age-related hearing loss (ARHL) is a common sensory impairment with complex underlying mechanisms. In our previous study, we performed a meta-analysis of genome-wide association studies (GWAS) in mice and identified a novel locus on chromosome 18 associated with ARHL specifically linked to a 32 kHz tone burst stimulus. Consequently, we investigated the role of Formin Homology 2 Domain Containing 3 (Fhod3), a newly discovered candidate gene for ARHL based on the GWAS results. We observed Fhod3 expression in auditory hair cells (HCs) primarily localized at the cuticular plate (CP). To understand the functional implications of Fhod3 in the cochlea, we generated Fhod3 overexpression mice (Pax2-Cre+/-; Fhod3Tg/+) (TG) and HC-specific conditional knockout mice (Atoh1-Cre+/-; Fhod3fl/fl) (KO). Audiological assessments in TG mice demonstrated progressive high-frequency hearing loss, characterized by predominant loss of outer hair cells, and a decreased phalloidin intensities of CP. Ultrastructural analysis revealed loss of the shortest row of stereocilia in the basal turn of the cochlea, and alterations in the cuticular plate surrounding stereocilia rootlets. Importantly, the hearing and HC phenotype in TG mice phenocopied that of the KO mice. These findings suggest that balanced expression of Fhod3 is critical for proper CP and stereocilia structure and function. Further investigation of Fhod3 related hearing impairment mechanisms may lend new insight towards the myriad mechanisms underlying ARHL, which in turn could facilitate the development of therapeutic strategies for ARHL.

Hydrogen-triggered metal filament rupture in Cu-based resistance switches.

Cation-based resistance switches have been considered as promising candidates for memory cells and other novel devices. So far, the most accepted switching processes of such devices are based on the formation/rupture of metallic filaments between two electrodes. Although many recent studies have identified the existence of H2O (and resulting -OH groups) in such devices, their effects on the switching process are still unclear. In the present work, by taking Cu/Ta2O5/Pt device as an example, we have theoretically revealed that H ions may dissociate from -OH groups and accumulate onto the Cu filament in amorphous Ta2O5. After that, the adsorbed H ions will induce a series of changes, such as the elongation of the adjacent Cu-Cu bonds, the weakening of the Cu-Cu bonds, the increase of charge on Cu cations, and the enhancement of diffusivities of Cu cations, all of which eventually lead to the rupture of the Cu filament. Interestingly, our proposed 'H-triggered metal filament rupture' model is similar to the widely studied 'hydrogen embrittlement phenomenon'. The crucial point of this model is the high catalytic activity of Cu towards the splitting of -OH group. Consequently, it is expected that this model could be applicable to other Cu-cation based resistance switches.

Cation-based resistance switches have been considered as the promising candidates for memory cells and other novel devices. So far, the most accepted switching processes of such devices are based on the forming/rupture of metallic filaments between two electrodes. Although many recent studies have identified the existence of H₂O (and as-resulted -OH groups) in such devices, their effects on the switching process are still unclear. In the present work, by taking Cu/Ta₂O₅/Pt device as an example, we have theoretically proposed that the H ions take the very important role during the rupture process of Cu filament in such device. Interestingly, our proposed 'H-triggered metal filament rupture' model is similar to the widely studied 'Hydrogen Embrittlement' phenomenon in the industry field, which serves as additional evidence supporting the credibility of such model. The crucial point of mechanism of this model is considered to be the high catalytic activity of Cu towards the splitting of -OH group. Consequently, it is expected that this model could be applicable to other Cu-cation based resistance switches.

A Novel Multi-Functional Fluorescence Probe for the Detection of Al3+/Zn2+/Cd2+ and its Practical Applications.

A novel multi-functional fluorescence probe HMIC based on hydrazide Schiff base has been successfully synthesized and characterized. It can distinguish Al3+/Zn2+/Cd2+ in ethanol, in which fluorescence emission with different colors (blue for Al3+, orange for Zn2+, and green for Cd2+) were presented. The limits of detection of HMIC towards three ions were calculated from the titration curve as 7.70 × 10- 9 M, 4.64 × 10- 9 M, and 1.35 × 10- 8 M, respectively. The structures of HMIC and its complexes were investigated using UV-Vis spectra, Job's plot, infrared spectra, mass spectrometry, 1H-NMR and DFT calculations. Practical application studies have also demonstrated that HMIC can be applied to real samples with a low impact of potential interferents. Cytotoxicity and cellular imaging assays have shown that HMIC has good cellular permeability and potential antitumor effects. Interestingly, HMIC can image Al3+, Zn2+ and Cd2+ in the cells with different fluorescence signals.

Mechanistic insights into photoinduced energy and charge transfer dynamics between magnesium-centered tetrapyrroles and carbon nanotubes.

Functionalizing single-walled carbon nanotubes (SWNTs) with light-harvesting molecules is a facile way to construct donor-acceptor nanoarchitectures with intriguing optoelectronic properties. Magnesium-centered bacteriochlorin (MgBC), chlorin (MgC), and porphyrin (MgP) are a series of tetrapyrrole macrocycles comprising a central metal and four coordinated aromatic or antiaromatic five-membered rings linked by methine units, which show excellent visible light absorption. To delineate the effects of the aromaticity of coordinated rings on the optoelectronic properties of the nanocomposites, the photoinduced energy and charge transfer dynamics between Mg-centered tetrapyrroles and SWNTs are explored. The results show that excited energy transfer (EET) can occur within MgP@SWNT ascribed to the stabilization of the highest occupied molecular orbital (HOMO) in MgP with the increase of aromatic coordinated rings, while only electron transfer can take place in MgBC@SWNT and MgC@SWNT. Non-adiabatic dynamics simulations demonstrate that electron and hole transfer from MgP to SWNT is asynchronous. The electron transfer is ultrafast with a timescale of ca. 50 fs. By contrast, the hole transfer is significantly suppressed, although it can be accelerated to some extent when using a lower excitation energy of 2.2 eV as opposed to 3.1 eV. Further analysis reveals that the large energy gaps between charge-donor and charge-acceptor states play a crucial role in regulating photoexcited state relaxation dynamics. Our theoretical insights elucidate the structure-functionality interrelations between Mg-centered tetrapyrroles and SWNTs and provide a comprehensive understanding of the underlying charge transfer mechanism within MgP@SWNT nanocomposites, which paves the way for the forthcoming development of SWNT-based photo-related functional materials with targeted applications.

Cooperativity between H-bonds and tetrel bonds. Transformation of a noncovalent C⋯N tetrel bond to a covalent bond.

The dimers and trimers formed by imidazole (IM) and F2TO (T = C, Si, Ge) are studied by ab initio calculations. IM can engage in either a NH⋯O H-bond with F2TO or a T⋯N tetrel bond (TB) with the π-hole above the T atom. The latter is a true noncovalent TB for T = C but is a much shorter and stronger covalent bond with F2SiO or F2GeO. When a second IM is added, the cooperativity emerging from its H-bond with the first IM makes it a stronger nucleophile, leading to two minima with F2CO. The first structure contains a long noncovalent C⋯O TB and there is a much shorter covalent bond in the other, with a small energy barrier separating them. The same sort of double minimum occurs when the two IM units are situated parallel to one another in a stacked geometry.

Near-Infrared Dual-Emission of a Thiolate-Protected Au42 Nanocluster: Excited States, Nonradiative Rates, and Mechanism.

Both DFT and TD-DFT methods are used to elaborate on the excited-state properties and dual-emission mechanism of a thiolate-protected Au42 nanocluster. A three-state model (S0, S1, and T1) is proposed with respect to the results. The intersystem crossing (ISC) process from S1 to T1 benefits from a small reorganization energy due to the similar geometric structures of S1 and T1. However, the ISC process is suppressed by relatively small spin-orbit coupling resulting from the similarity of the electronic structures of S1 and T1. As a result of the counterbalance, the ISC rate is comparable with the fluorescence emission rate. In the T1 state, the phosphorescence emission prevails the reverse ISC process back to the S1 state. Taken together, fluorescence and phosphorescence are achieved simultaneously. The present work provides deep mechanistic insights to aid the rational design of NIR dual-emissive metal nanoclusters.

The Tetrel Bonds of Hypervalent Halogen Compounds.

The tetrel bond between PhXF2Y(TF3) (T = C and Si; X = Cl, Br, and I; Y = F and Cl) and the electron donor MCN (M = Li and Na) was investigated at the M06-2X/aug-cc-pVDZ level of theory. As the electronegativity of the halogen atom X increases, the strength of the tetrel bond also increases, but as the electronegativity of the halogen atom Y increases, the strength of the tetrel bond decreases. The magnitude of the interaction energy in most -CF3 complexes was found to be less than 10 kcal/mol, but to exceed 11 kcal/mol for PhClF2Cl(CF3)⋯NCNa. The tetrel bond is greatly enhanced when the -SiF3 group interacts with LiCN or NaCN, with the largest interaction energy approaching 100 kcal/mol and displaying a covalent Si⋯N interaction. Along with this enhancement, the Si⋯N distance was found to be less than the X-Si bond length, the -SiF3 group to be closer to the N atom, and in most -SiF3 systems, the X-Si-F angle to be less than 90°; the -SiF3 group therefore undergoes inversion and complete transfer in some systems.

Metal-Doped C3B Monolayer as the Promising Electrocatalyst for Hydrogen/Oxygen Evolution Reaction: A Combined Density Functional Theory and Machine Learning Study.

The development of high-efficiency electrocatalysts for hydrogen evolution reduction (HER)/oxygen evolution reduction (OER) is highly desirable. In particular, metal borides have attracted much attention because of their excellent performances. In this study, we designed a series of metal borides by doping of a transition metal (TM) in a C3B monolayer and further explored their potential applications for HER/OER via density functional theory (DFT) calculations and machine learning (ML) analysis. Our results revealed that the |ΔG*H| values of Fe-, Ag-, Re-, and Ir-doped C3B are approximately 0.00 eV, indicating their excellent HER performances. On the other hand, among all the considered TM atoms, the Ni- and Pt-doped C3B exhibit excellent OER activities with the overpotentials smaller than 0.44 V. Together with their low overpotentials for HER (<0.16 V), we proposed that Ni/C3B and Pt/C3B could be the potential bifunctional electrocatalysts for water splitting. In addition, the ML method was employed to identify the important factors to affect the performance of the TM/C3B electrocatalyst. Interestingly, the results showed that the OER performance is closely related to the inherent properties of TM atoms, i.e., the number of d electrons, electronegativity, atomic radius, and first ionization energy; all these values could be directly obtained without DFT calculations. Our results not only proposed several promising electrocatalysts for HER/OER but also suggested a guidance to design the potential TM-boron (TM-B)-based electrocatalysts.

C∙∙∙O and Si∙∙∙O Tetrel Bonds: Substituent Effects and Transfer of the SiF3 Group.

The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF3-1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO2, CN, F, CH3, OH, OCH3, NH2, and Li) is examined by quantum chemical means. The Si∙∙∙O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C∙∙∙O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite effect. The SiF3 group transfers roughly halfway between the N of the acid and the O of the base without the aid of cooperative effects from a third entity.

Altered Fhod3 Expression Involved in Progressive High-Frequency Hearing Loss via Dysregulation of Actin Polymerization Stoichiometry in The Cuticular Plate.

Age-related hearing loss (ARHL) is a common sensory impairment with comlex underlying mechanisms. In our previous study, we performed a meta-analysis of genome-wide association studies (GWAS) in mice and identified a novel locus on chromosome 18 associated with ARHL specifically linked to a 32 kHz tone burst stimulus. Consequently, we investigated the role of Formin Homology 2 Domain Containing 3 (Fhod3), a newly discovered candidate gene for ARHL based on the GWAS results. We observed Fhod3 expression in auditory hair cells (HCs) and primarily localized at the cuticular plate (CP). To understand the functional implications of Fhod3 in the cochlea, we generated Fhod3 overexpression mice (Pax2-Cre+/-; Fhod3Tg/+) (TG) and HC-specific conditional knockout mice (Atoh1-Cre+/-; Fhod3fl/fl) (KO). Audiological assessments in TG mice demonstrated progressive high-frequency hearing loss, characterized by predominant loss of outer HCs and decrease phalloidin intensities of CP. Ultrastructural analysis revealed shortened stereocilia in the basal turn cochlea. Importantly, the hearing and HC phenotype in TG mice were replicated in KO mice. These findings indicate that Fhod3 plays a critical role in regulating actin dynamics in CP and stereocilia. Further investigation of Fhod3-related hearing impairment mechanisms may facilitate the development of therapeutic strategies for ARHL in humans.

scMCs: a framework for single-cell multi-omics data integration and multiple clusterings.

MOTIVATION: The integration of single-cell multi-omics data can uncover the underlying regulatory basis of diverse cell types and states. However, contemporary methods disregard the omics individuality, and the high noise, sparsity, and heterogeneity of single-cell data also impact the fusion effect. Furthermore, available single-cell clustering methods only focus on the cell type clustering, which cannot mine the alternative clustering to comprehensively analyze cells. RESULTS: We propose a single-cell data fusion based multiple clustering (scMCs) approach that can jointly model single-cell transcriptomics and epigenetic data, and explore multiple different clusterings. scMCs first mines the omics-specific and cross-omics consistent representations, then fuses them into a co-embedding representation, which can dissect cellular heterogeneity and impute data. To discover the potential alternative clustering embedded in multi-omics, scMCs projects the co-embedding representation into different salient subspaces. Meanwhile, it reduces the redundancy between subspaces to enhance the diversity of alternative clusterings and optimizes the cluster centers in each subspace to boost the quality of corresponding clustering. Unlike single clustering, these alternative clusterings provide additional perspectives for understanding complex genetic information, such as cell types and states. Experimental results show that scMCs can effectively identify subcellular types, impute dropout events, and uncover diverse cell characteristics by giving different but meaningful clusterings. AVAILABILITY AND IMPLEMENTATION: The code is available at www.sdu-idea.cn/codes.php?name=scMCs.

Social distancing cut down the prevalence of acute otitis media in children.

Objectives: To evaluate the additional, unintended benefits of social distancing in cutting down the prevalence of acute otitis media (AOM) in children, especially during coronavirus disease 2019 (COVID-19) periods. Methods: The daily outpatient attendance of AOM for childhood (from 6 months to 12 years) was compared in the tertiary hospital in Shanghai during pre-COVID-19 and COVID-19 year. Results: A total of 24,543 AOM cases were included from 2015 to 2020. When age was taken into account, children in kindergarten (aged 4-6) constitute 66.2% (16,236/24,543) of all case, followed by primary school students (6,441/24,543, 26.2%) and preschoolers <3 years old (1,866/24,543, 7.6%). There was an estimated 63.6% (54.32-70.36%) reduction in the daily outpatient attendance of AOM associated with the introduction of social distancing in 2020 (COVID-19 year). The epidemic trend of AOM in 2015-2019 was characterized by seasonal fluctuations, with highest incidence in December (18.8 ± 0.5%) and lower in February (4.5 ± 0.2%), June (3.7 ± 0.7%) and August (3.5 ± 0.5%). And distribution characteristics of different ages in COVID-19 period broadly in line with that in non-pandemic period. Conclusion: Seasonal fluctuation in the prevalence of AOM was observed in pre-COVID-19 period (2015-2019), with a peak in winter and a nadir in summer. The >50% drop of outpatient attendance of AOM in 2020 (COVID-19 year) suggest that social distancing, mask effects and good hand hygiene can significantly reduce the incidence of AOM, which provides a preventive and therapeutic point of view for AOM.

Motion coordination and dexterous manipulation for underwater vehicle-manipulator systems.

This paper addresses the redundancy resolution problem for underwater vehicle-manipulator systems (UVMSs). More specifically, a new redundancy resolution approach with motion coordination and dexterous manipulation is presented to guarantee the tracking accuracy of the end-effector while avoiding singular configurations of the manipulator. The task-priority redundancy resolution framework is adopted to achieve an effective coordinated motion of the vehicle and manipulator while exploiting the redundant degrees of freedom available. A dexterous manipulation task with low priority is proposed to reconfigure the UVMS into a more dexterous configuration by keeping the end-effector within the designed heuristic subset. An inequality-based singularity avoidance task is inserted into the redundancy resolution framework as a high-priority task to keep the measure of manipulability above a specified minimum value. Experimental results verify that the proposed approach significantly improves the dexterity and coordination of the UVMS.

Triel Bonds with Au Atoms as Electron Donors.

The novel triel bonds of BX3 (X=H, F, Cl, Br, and I) and C5 H5 B as electron acceptors and AuR2 (R=Cl and CH3 ) as an electron donor were explored. The triel bond is a primary driving force for most complexes, while the contribution from a halogen-chlorine interaction in BX3 -AuCl2 (X=Cl, Br, and I) and an iodine-Au interaction in BI3 -Au(CH3 )3 is also very important. Interestingly, the positively charged Au atom of AuCl2 can attractively bind with the holes of BX3 and C5 H5 B. The interaction energy lies in the range of 1 and 80 kcal/mol, in the order X=F

Search for Osme Bonds with π Systems as Electron Donors.

The Osme bond is defined as pairing a Group 8 metal atom as an electron acceptor in a noncovalent interaction with a nucleophile. DFT calculations with the ωB97XD functional consider MO4 (M = Ru, Os) as the Lewis acid, paired with a series of π electron donors C2H2, C2H4, C6H6, C4H5N, C4H4O, and C4H4S. The calculations establish interaction energies in the range between 9.5 and 26.4 kJ/mol. Os engages in stronger interactions than does Ru, and those involving more extensive π-systems within the aromatic rings form stronger bonds than do the smaller ethylene and acetylene. Extensive analysis questions the existence of a true Osme bond, as the bonding chiefly involves interactions with the three O atoms of MO4 that lie closest to the π-system, via π(C-C)→σ*(M-O) transfers. These interactions are supplemented by back donation from M-O bonds to the π*(CC) antibonding orbitals of the π-systems. Dispersion makes a large contribution to these interactions, higher than electrostatics and much greater than induction.

Abnormalities of the Halogen Bonds in the Complexes between Y2CTe (Y = H, F, CH3) and XF (X = F, Cl, Br, I).

In this work, the hydrogen bonds and halogen bonds in the complexes between Y2CTe (Y = H, F, CH3) and XF (X = F, Cl, Br, I) have been studied by quantum chemical calculations. We found three interesting abnormalities regarding the interactions. Firstly, the strength of halogen bonds increases in the order of IF < BrF < ClF < F2. Secondly, the halogen bonds formed by F2 are very strong, with an interaction energy in the range between −199.8 and −233.1 kJ/mol. Thirdly, all the halogen bonds are stronger than the hydrogen bonds in the systems we examined. All these results are against the general understanding of halogen bonds. These apparent abnormal properties are reconciled with the high polarizability of the Te atom and the strong inducing effect of F on the Te atom of Y2CTe. These findings provide a new perspective on halogen bonds. Additionally, we also proposed bonding distance-based methods to compare the strength of halogen/hydrogen bonds formed between different donor atoms and the same acceptor atom.

Enhancing Interfacial and Electromagnetic Interference Shielding Properties of Carbon Fiber Composites via the Hierarchical Assembly of the MWNT/MOF Interphase.

A metal-organic framework (MOF) based on a conjugated organic ligand and a transition-metal ion was designed and used to construct a novel multiwalled carbon nanotube (MWNT)/MOF interphase via hierarchical assembly on the carbon fiber (CF) surface and was compared to various interphases established by MWNT and MOF. An intertwined MWNT and MOF "jujube core" was randomly dispersed on MWNT@CF and MOF@CF surfaces, while interpenetrating structures with the MWNT network and MOF jujube core were simultaneously observed on MWNT/MOF@CF due to coordination bonds and π-π conjugation effects, which were derived from the MWNT template with carboxyl groups and sp2-hybridized domains as well as the secondary growth of MOF to promote self-assembly and the connection of MOF. The transverse fiber bundle test (TFBT) strength and interfacial shear strength (IFSS) of the MWNT/MOF@CF composite were 36.9, 6.1, and 20.8%, 16.3% higher than those of MWNT@CF and MOF@CF composites, which were attributed to the smoothed modulus transition of the stiffening interphase formed by the MWNT/MOF hybrid structure as "armor" to effectively buffer the stress transfer between a carbon fiber and the resin matrix. Compared to MWNT@CF and MOF@CF composites, MWNT/MOF@CF composites had the highest EMI shielding effectiveness, which was attributed to the combined effects of multiple reflections, conductive loss, and interface polarization from the interpenetrating MWNT/MOF hybrid structures, which realized the integration of the structure and function of the carbon fiber composites.

CH4 activation by PtX+ (X = F, Cl, Br, I).

Reactions of PtX+ (X = F, Cl, Br, I) with methane have been investigated at the density functional theory (DFT) level. These reactions take place more easily along the low-spin potential energy surface. For HX (X = F, Cl, Br, I) elimination, the formal oxidation state of the metal ion appears to be conserved, and the importance of this reaction channel decreases in going as the sequence: X = F, Cl, Br, I. A reversed trend is observed in the loss of H2 for X = F, Cl, Br, while it is not favorable for PtI+ in the loss of either HI or H2. For HX eliminations, the transfer form of H is from proton to atom, last to hydride, and the mechanisms are from PCET to HAT, last to HT for the sequence of X = F, Cl, Br, I. One reason is mainly due to the electronegativity of halogens. Otherwise, the mechanisms of HX eliminations also can be explained by the analysis of Frontier Molecular Orbitals. While for the loss of H2, the transfer of H is in the form of hydride for all the X ligands. Noncovalent interactions analysis also can be explained the reaction mechanisms.

Enhancement of tetrel bond involving tetrazole-TtR3 (Tt = C, Si; R = H, F). Promotion of SiR3 transfer by a triel bond.

When attached to a tetrazole, a TtR3 group (Tt = C, Si; R = H, F) engages in a Tt⋯N tetrel bond (TtB) with the Lewis base NCM (M = Li, Na). MP2/aug-cc-pVTZ calculations find that the Si⋯N TtB is rather strong, more than 20 kcal mol-1 for SiH3, and between 46 and 53 kcal mol-1 for SiF3. The C⋯N TtBs are relatively weaker, less than 8 kcal mol-1. All of these bonds are intensified when a BH3 or BF3 molecule forms a triel bond to a N atom of the tetrazole ring, particularly for the C⋯N TtB, up to 11 kcal mol-1. In these triads, the SiR3 group displaces far enough along the line toward the base that it may be thought of as half transferred.