Consecutive C-C Coupling of CH and CO Mediated by Heteronuclear Metal Cations CuTa.

The conversion of methane and carbon dioxide to form C products is of great interest but presents a long-standing grand challenge due to the significant obstacle of activating the inert C-H and C═O bonds as well as forming the C-C bonds. Herein, the consecutive C-C coupling of CH and CO was realized by using heteronuclear metal cations CuTa, and the desorption of HC═C═O molecules was evidenced by state-of-the-art mass spectrometry. The CuTa reaction system is significantly different from the homonuclear metal systems of Cu and Ta.

Adaptative responses of Neurospora crassa by histidine kinases upon the attack of the arthropod Sinella curviseta.

Histidine kinases (HKs) are important sensor proteins in fungi and play an essential role in environmental adaptation. However, the mechanisms by which fungi sense and respond to fungivores attack via HKs are not fully understood. In this study, we utilized Neurospora crassa to investigate the involvement of HKs in responding to fungivores attack.

Dry Reforming of Methane to Syngas Mediated by Rhodium-Cobalt Oxide Cluster Anions RhCoO.

Dry reforming of methane (DRM) to syngas is an important route to co-convert CH and CO. However, the highly endothermic nature of DRM induces the thermocatalysis to commonly operate at high temperatures that inevitably causes coke deposition through pyrolysis of methane. Herein, benefiting from the mass spectrometric experiments complemented with quantum chemical calculations, we have discovered that the bimetallic oxide cluster RhCoO can mediate the co-conversion of CH and CO at room temperature giving rise to two free H molecules and two adsorbed CO molecules (CO).

Reactivity of Atomic Oxygen Radical Anions in Metal Oxide Clusters.

Atomic oxygen radical anion (O⋅) represents an important type of reactive centre that exists in both chemical and biological systems. Gas-phase atomic clusters can be studied under isolated and well controlled conditions. Studies of O⋅-containing clusters in the gas-phase provide a unique strategy to interpret the chemistry of O⋅ radicals at a strictly molecular level.

Experimental Reactivity of (MoO)O ( = 1-21) Cluster Anions with C-C Alkanes: A Simple Model to Predict the Reactivity with Methane.

Metal oxide clusters with atomic oxygen radical anions are important model systems to study the mechanisms of activating and transforming very stable alkane molecules under ambient conditions. It is extremely challenging to characterize the activation and conversion of methane, the most stable alkane molecule, by metal oxide cluster anions due to the low reactivity of the anionic species. In this study, using a ship-lock type reactor that could be run at relatively high pressure conditions to provide a high number of collisions in ion-molecule reactions, the rate constants of the reactions between (MoO)O ( = 1-21) cluster anions and the light alkanes (C-C) were measured under thermal collision conditions.

Conversion of Methane at Room Temperature Mediated by the Ta-Ta σ-Bond.

Metal-metal bonds constitute an important type of reactive centers for chemical transformation; however, the availability of active metal-metal bonds being capable of converting methane under mild conditions, the holy grail in catalysis, remains a serious challenge. Herein, benefiting from the systematic investigation of 36 metal clusters of tantalum by using mass spectrometric experiments complemented with quantum chemical calculations, the dehydrogenation of methane at room temperature was successfully achieved by 18 cluster species featuring σ-bonding electrons localized in single naked Ta-Ta centers. In sharp contrast, the other 18 remaining clusters, either without naked Ta-Ta σ-bond or with σ-bonding electrons delocalized over multiple Ta-Ta centers only exhibit molecular CH-adsorption reactivity or inertness.

Size-dependent reactivity of VO ( = 1-9) clusters with ethane.

Cost-effective and readily accessible 3d transition metals (TMs) have been considered as promising candidates for alkane activation while 3d TMs especially the early TMs are usually not very reactive with light alkanes. In this study, the reactivity of V and VO ( = 1-9) cluster cations towards ethane under thermal collision conditions has been investigated using mass spectrometry and density functional theory calculations. Among V ( = 1-9) clusters, only V can react with CH to generate dehydrogenation products and the reaction rate constants are below 10 cm molecule s.

Machine Learning for Experimental Reactivity of a Set of Metal Clusters toward C-H Activation.

Understanding the mechanisms of C-H activation of alkanes is a very important research topic. The reactions of metal clusters with alkanes have been extensively studied to reveal the electronic features governing C-H activation, while the experimental cluster reactivity was qualitatively interpreted case by case in the literature. Herein, we prepared and mass-selected over 100 rhodium-based clusters (RhVO and RhCoO) to react with light alkanes, enabling the determination of reaction rate constants spanning six orders of magnitude.

[Multi-scenario Simulation of Construction Land Expansion and Its Impact on Ecosystem Carbon Storage in Beijing-Tianjin-Hebei Urban Agglomeration].

It is of great practical significance for regional sustainable development and ecological construction to quantitatively analyze the impact of construction land expansion on terrestrial ecosystem carbon storage and to explore the optimization scheme of simulating construction land expansion to improve future ecosystem carbon storage. Based on the land use and cover change (LUCC) and other geospatial data of the Beijing-Tianjin-Hebei Urban Agglomeration from 2000 to 2020, this study utilized the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and the patch-generating land-use simulation (PLUS) model to assess and analyze the changes in ecosystem carbon stocks and spatial patterns regionally. In this study, we performed linear regression analysis to investigate the relationship between urban land expansion and changes in ecosystem carbon stocks for varying urban land proportion levels during two distinct time intervals, 2000-2010 and 2010-2020, which was conducted at a spatial resolution of 2 km.

Thermal Reactions of NiAlO and AlO with Methane: Reactivity Enhancement by Doping.

Investigation of the reactivity of heteronuclear metal oxide clusters is an important way to uncover the molecular-level mechanisms of the doping effect. Herein, we performed a comparative study on the reactions of CH with NiAlO and AlO cluster cations at room temperature to understand the role of Ni during the activation and transformation of methane. Mass spectrometric experiments identify that both NiAlO and AlO could bring about hydrogen atom abstraction reaction to generate CH radical; however, only NiAlO has the potential to stabilize [CH] moiety and then transform [CH] to CHO.

Activation of Methane by Rhodium Clusters on a Model Support CH.

Supported metals represent an important family of catalysts for the transformation of the most stable alkane, methane, under mild conditions. Here, using state-of-the-art mass spectrometry coupled with a newly designed double ion trap reactor that can run at high temperatures, we successfully immobilize a series of Rh ( = 4-8) cluster anions on a model support CH. Reactivity measurements at room temperature identify a significantly enhanced performance of large-sized RhCH toward methane activation compared to that of free Rh.

An integrated analysis of Sacituzumab govitecan in relapsed or refractory metastatic triple-negative breast cancer.

Background: Sacituzumab govitecan (SG) is an antibody-drug conjugate that targets the human trophoblast cell-surface antigen 2 to deliver SN-38 to cancer cells. In this study, we assessed the efficacy and safety of SG in patients with relapsed or refractory metastatic triple-negative breast cancer (RM-TNBC).

Methods: For this integrated analysis, from inception to January 2, 2023, we searched PubMed, Web of Science, Embase, and Cochrane library databases for prospective studies that evaluated SC in RM-TNBC patients.

C-H Activation by Iron-Vanadium Bimetallic Oxide Cluster Anions FeV O and FeV O : A Comparison with Scandium-Vanadium Oxide Clusters.

Late transition metal-bonded atomic oxygen radicals (LTM-O⋅ ) have been frequently proposed as important active sites to selectively activate and transform inert alkane molecules. However, it is extremely challenging to characterize the LTM-O⋅ -mediated elementary reactions for clarifying the underlying mechanisms limited by the low activity of LTM-O⋅ radicals that is inaccessible by the traditional experimental methods. Herein, benefiting from our newly-designed ship-lock type reactor, the reactivity of iron-vanadium bimetallic oxide cluster anions FeV O and FeV O featuring with Fe-O⋅ radicals to abstract a hydrogen atom from C -C alkanes has been experimentally characterized at 298 K, and the rate constants are determined in the orders of magnitude of 10 to 10  cm molecule  s , which are four orders of magnitude slower than the values of counterpart ScV O and ScV O clusters bearing Sc-O⋅ radicals.

Tyrosine Kinase Inhibitors for Pediatric Leukemia: History and Current Status.

Tyrosine kinase inhibitors (TKIs) block the activity of tyrosine kinases by competitive inhibition of ATP at the catalytic tyrosine kinase binding site and inhibit oncogenic signaling. One important target of TKIs is BCR-ABL1, which is constitutively activated in leukemia cells. In this review, we briefly describe the development of TKIs from the first generation to the third generation, and summarize their use in the treatment of chronic myeloid leukemia and acute lymphoblastic leukemia in children.

Pyrolysis of mass-selected (VO)O (N = 1-6) clusters in a high-temperature linear ion trap reactor.

A high-temperature linear ion trap that can stably run up to 873 K was newly designed and installed into a homemade reflectron time-of-flight mass spectrometer coupled with a laser ablation cluster source and a quadrupole mass filter. The instrument was used to study the pyrolysis behavior of mass-selected (VO)O (N = 1-6) cluster anions and the dissociation channels were clarified with atomistic precision. Similar to the dissociation behavior of the heated metal oxide cluster cations reported in literature, the desorption of either atomic oxygen atom or molecular O prevailed for the (VO)O clusters with N = 2-5 at 873 K.

Fluorescent Talarolactones from Talaromyces sp.

(+)-Talarolactone C (1), Talarolactone A (2), Talarolactone B (3, sulfoxide derivative), and Talarolactone D (4, sulfone derivative) were isolated from Talaromyces sp. which was cultured in rice medium with sodium butyrate. The structures of talarolactone analogs above were characterized by a combination of spectroscopic, X-ray crystallographic, and computational methods.

Conversion of CH Catalyzed by Gas Phase Ions Containing Metals.

Methane is an abundant and cheap feedstock to produce valuable chemicals. The catalytic reaction of methane conversion generally requires the participation of multiple molecules (such as two or three CH molecules, O , CO , etc.).

Conversion of Methane with Oxygen to Produce Hydrogen Catalyzed by Triatomic Rh Cluster Anion.

Metal catalysts, especially noble metals, have frequently been prepared upon downsizing from nanoparticles to subnanoclusters to catalyze the important reaction of partial oxidation of methane (POM) in order to optimize the catalytic performance and conserve metal resources. Here, benefiting from mass spectrometric experiments in conjunction with photoelectron spectroscopy and quantum chemical calculations, we successfully determine that metal cluster anions composed of only three Rh atoms (Rh ) can catalyze the POM reaction with O to produce 2H + CO under thermal collision conditions (∼300 K). The interdependence between CH and O to protect Rh from collapse and to promote conversion of CH → 2H has been clarified.

Methane Activation by (MoO ) O Cluster Anions: The Importance of Orbital Orientation.

The reactivity of the molybdenum oxide cluster anion (MoO ) O , bearing an unpaired electron at a bridging oxygen atom (O ), towards methane under thermal collision conditions has been studied by mass spectrometry and density functional theory calculations. This reaction follows the mechanism of hydrogen atom transfer (HAT) and is facilitated by the O radical center. The reactivity of (MoO ) O can be traced back to the appropriate orientation of the lowest unoccupied molecular orbitals (LUMO) that is essentially the 2p orbital of the O atom.

Rhodium chemistry: A gas phase cluster study.

Due to the extraordinary catalytic activity in redox reactions, the noble metal, rhodium, has substantial industrial and laboratory applications in the production of value-added chemicals, synthesis of biomedicine, removal of automotive exhaust gas, and so on. The main drawback of rhodium catalysts is its high-cost, so it is of great importance to maximize the atomic efficiency of the precious metal by recognizing the structure-activity relationship of catalytically active sites and clarifying the root cause of the exceptional performance. This Perspective concerns the significant progress on the fundamental understanding of rhodium chemistry at a strictly molecular level by the joint experimental and computational study of the reactivity of isolated Rh-based gas phase clusters that can serve as ideal models for the active sites of condensed-phase catalysts.

Catalytic Co-Conversion of CH and CO Mediated by Rhodium-Titanium Oxide Anions RhTiO.

Catalytic co-conversion of methane with carbon dioxide to produce syngas (2 H +2 CO) involves complicated elementary steps and almost all the elementary reactions are performed at the same high temperature conditions in practical thermocatalysis. Here, we demonstrate by mass spectrometric experiments that RhTiO promotes the co-conversion of CH and CO to free 2 H +CO and an adsorbed CO (CO ) at room temperature; the only elementary step that requires the input of external energy is desorption of CO from the RhTiO CO to reform RhTiO . This study not only identifies a promising active species for dry (CO ) reforming of methane to syngas, but also emphasizes the importance of temperature control over elementary steps in practical catalysis, which may significantly alleviate the carbon deposition originating from the pyrolysis of methane.

Photooxidation of Isoprene by Titanium Oxide Cluster Anions with Dimensions up to a Nanosize.

Titania (TiO) nanoparticles are active photocatalysts, and isoprene (CH) is a biogenic volatile organic compound that contributes crucially to global particulate matter generation. Herein, the direct photooxidation of isoprene by titanium oxide cluster anions with dimensions up to a nanosize by both ultraviolet (UV) and visible (Vis) light excitations has been successfully identified through mass spectrometric experiments combined with quantum chemistry calculations. The potential role of "dry" titania in atmospheric isoprene oxidation has been revealed, and a clear picture of the photooxidation mechanism on titanium oxide nanoparticles has been provided explicitly at the molecular level.