A conserved molecular logic for neurogenesis to gliogenesis switch in the cerebral cortex.

During development, neural stem cells in the cerebral cortex, also known as radial glial cells (RGCs), generate excitatory neurons, followed by production of cortical macroglia and inhibitory neurons that migrate to the olfactory bulb (OB). Understanding the mechanisms for this lineage switch is fundamental for unraveling how proper numbers of diverse neuronal and glial cell types are controlled. We and others recently showed that Sonic Hedgehog (Shh) signaling promotes the cortical RGC lineage switch to generate cortical oligodendrocytes and OB interneurons. During this process, cortical RGCs generate intermediate progenitor cells that express critical gliogenesis genes Ascl1, Egfr, and Olig2. The increased Ascl1 expression and appearance of Egfr+ and Olig2+ cortical progenitors are concurrent with the switch from excitatory neurogenesis to gliogenesis and OB interneuron neurogenesis in the cortex. While Shh signaling promotes Olig2 expression in the developing spinal cord, the exact mechanism for this transcriptional regulation is not known. Furthermore, the transcriptional regulation of Olig2 and Egfr has not been explored. Here, we show that in cortical progenitor cells, multiple regulatory programs, including Pax6 and Gli3, prevent precocious expression of Olig2, a gene essential for production of cortical oligodendrocytes and astrocytes. We identify multiple enhancers that control Olig2 expression in cortical progenitors and show that the mechanisms for regulating Olig2 expression are conserved between the mouse and human. Our study reveals evolutionarily conserved regulatory logic controlling the lineage switch of cortical neural stem cells.

High-Tc Ferromagnetic Semiconductor in Thinned 3D Ising Ferromagnetic Metal Fe3GaTe2.

Emergent phenomena in exfoliated layered transition metal compounds have attracted much attention in the past several years. Especially, pursuing a ferromagnetic insulator is one of the exciting goals for stimulating a high-performance magnetoelectrical device. Here, we report the transition from a metallic to high-Tc semiconductor-like ferromagnet in thinned Fe3GaTe2, accompanied with competition among various magnetic interactions. As evidenced by critical exponents, Fe3GaTe2 is the first layered ferromagnet described by a 3D Ising model coupled with long-range interactions. An extra magnetic phase from competition between ferromagnetism and antiferromagnetism emerges at a low field below Tc. Upon reducing thickness, the Curie temperature (Tc) monotonically decreases from 342 K for bulk to 200 K for 1-3 nm flakes, which is the highest Tc reported as far as we know. Furthermore, a semiconductor-like behavior has been observed in such 1-3 nm flakes. Our results highlight the importance of Fe3GaTe2 in searching for ferromagnetic insulators, which may benefit spintronic device fabrication.

CO2 Hydrogenation to CH3OH on Metal-Doped TiO2(110): Mechanisms, Strain Effect and a New Thermodynamic-Kinetic Relation.

Surface strain and linear thermodynamic-kinetic relation are interesting topics in catalysis. Development of low temperature methanol catalysts of high activity and selectivity is of particularly importance for conversion of CO2 to methanol. In the present paper CO2 hydrogenation to methanol on Znx@TiO2(110) (x=0-2) was explored using density functional calculations and microkinetic simulations. The reaction mechanisms on the three model systems were determined and it is shown that Zn2@TiO2(110) is the most active. The most favorable pathway on Zn2@TiO2(110) is identified and CO2+H to HCOO is found to be the rate-controlling step. It is demonstrated that there is a linear relation (named AEB relation) between the adsorption energies of the initial states and the barriers for the controlling step on the 18 systems studied. Calculations on strained surfaces show that the AEB relation exists within ±1 % strain. Sr2@TiO2(110) and -1 % strained CaZn and ZnCu doped TiO2(110) are potential good low temperature catalysts and deserve experimental testing.

Antiferromagnetic Frustration Behavior with Face-Sharing CuAs4 Tetrahedrons in Conducting ACu6As3 (A = Li and Na).

New mixed-valence copper pnictides ACu6As3 (A = Li and Na) adopt a quasi-2D structure type, featuring alkalis and [Cu6As3]- slabs along the c-axis alternatively. The face-sharing connection between CuAs4 polyhedra leads to a higher valence state for the inside Cu ions than that of Cu ions with the other connectivity way. This is confirmed by X-ray photoemission spectroscopy results. The Cu2+ with near spin 1/2 located on bilayer triangular lattice is found to exhibit a peculiar hump in magnetic susceptibility along the c-axis and, most strikingly, nearly a constant at low temperatures from 1.8 K down to 0.4 K. Besides, high hole mobilities, 68.58 and 645.16 cm2 V-1 S-1, are observed in LiCu6As3 and NaCu6As3, respectively. These compounds provide a novel material system for researching the relationship among structure, valence state, and spin correlation in frustrated lattice.

Comparative simulations of methanol steam reforming on PdZn alloy using kinetic Monte Carlo and mean-field microkinetic model.

Methanol steam reforming (MSR) is an attractive route for producing clean energy hydrogen. PdZn alloys are extensively studied as potential MSR catalysts for their stability and high CO2 selectivity. Here, we investigated the reaction mechanism using density functional calculations, mean-field microkinetic modeling (MF-MKM), and kinetic Monte Carlo (kMC) simulations. To overcome the over-underestimation of CO2 selectivity by log-kMC, an ads-kMC algorithm is proposed in which the adsorption/desorption rate constants were reduced under certain requirements and the diffusion process was treated by redistributing surface species each time an event occured. The simulations show that the dominant pathway to CO2 at low temperatures is CH3OH → CH3O → CH2O → H2COOH → H2COO → HCOO → CO2. The ads-kMC predicted OH coverage is 2-3 times that of MF-MKM, while they produce similar coverage for other species. Analyses indicate that surface OH promotes the dehydrogenation of CH3OH, CH3O, and H2COOH significantly and plays a key role in the MSR process. The dissociation of water/methanol is the most important rate-limiting/rate-inhibiting step. The CO2 selectivity obtained by the two methods is close to each other and consistent with the experimental trend with temperature. Generally, the ads-kMC results agree with the MF-MKM ones, supporting the previous finding that kMC and MF-MKM predict similar results if the diffusion is very fast and adsorbate interactions are neglected. The present study sheds light on the MSR process on PdZn alloys, and the proposed scheme to overcome the stiff problems in kMC simulations is worthy of being extended to other systems.

Global insights from local actions: a case study on enhancing flood disaster management efficiency in China's Greater Bay Area.

This study examines the flood disaster management network within the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2015 to 2021, identifying government department involvement and influence shifts. Key findings indicate a decrease in the centrality of the Public Security Office and Department of Transportation, suggesting a strategic shift toward more specialized, technology-driven disaster management. Conversely, the Science Bureau's increased engagement, from 8.43% to 12.84%, highlights a policy shift toward scientific research and technological innovation in managing flood risks. The analysis reveals underutilized communication between the Central Committee, the Poverty Alleviation Office, and the Publicity Department, highlighting opportunities for improved integration in disaster management and public communication strategies. To address these issues, the study suggests strengthening inter-departmental collaboration to leverage technological advancements in disaster management. It also recommends integrating flood disaster management with poverty alleviation initiatives to support affected populations comprehensively. Increasing the involvement of the Publicity Department is crucial for improving timely and transparent communication of flood-related data to the public. The conclusions advocate for an adaptive, strategically planned network approach to flood disaster management in the GBA, aiming to bolster responsiveness and preparedness for future flood events.

Amalgamation of DNAzymes and Nanozymes in a Coronazyme.

Artificial enzymes such as nanozymes and DNAzymes are economical and stable alternatives to natural enzymes. By coating Au nanoparticles (AuNPs) with a DNA corona (AuNP@DNA), we amalgamated nanozymes and DNAzymes into a new artificial enzyme with catalytic efficiency 5 times higher than AuNP nanozymes, 10 times higher than other nanozymes, and significantly greater than most of the DNAzymes on the same oxidation reaction. The AuNP@DNA demonstrates excellent specificity as its reactivity on a reduction reaction does not change with respect to pristine AuNP. Single-molecule fluorescence and force spectroscopies and density functional theory (DFT) simulations indicate a long-range oxidation reaction initiated by radical production on the AuNP surface, followed by radical transport to the DNA corona, where the binding and turnover of substrates take place. The AuNP@DNA is named coronazyme because of its natural enzyme mimicking capability through the well-orchestrated structures and synergetic functions. By incorporating different nanocores and corona materials beyond DNAs, we anticipate that the coronazymes represent generic enzyme mimics to carry out versatile reactions in harsh environments.

Is HER2 ultra-low breast cancer different from HER2 null or HER2 low breast cancer? A study of 1363 patients.

OBJECTIVE: This study aims to analyze whether there are any differences in clinicopathological features and prognosis between HER2 ultra-low, HER2-null, and HER2-low expression in Chinese breast cancer (BC) patients. METHODS: The clinicopathological data of 1363 HER2-negative BC patients were retrospectively collected (from January 2018 to December 2019). HER2 status was further classified into HER2-null, HER2 ultra-low, and HER2-low. HER2-null expression is defined as infiltrating cancer cells completely free of staining. HER2 ultra-low expression is defined as ≤10% of infiltrating cancer cells showing incomplete and faint/weak membrane staining. HER2-low expression is defined as HER2 immunohistochemistry (IHC) 1+ or 2+ with negative in situ hybridization (ISH) assay. RESULTS: Of 1363 patients, there were 86 (6.3%) HER2-null patients, 395 (29.0%) HER2 ultra-low patients, and 882 (64.7%) HER2-low patients. HER2 ultra-low patients were different from HER2-low patients in terms of N stage, hormone receptor (HR) status, Ki-67 expression, and type of surgery. There were also significant differences in histologic type and postoperative endocrine therapy between HER2 ultra-low and HER2-null patients. HR+ (81.0%) tumors was more common than HR- (19.0%) in HER2 ultra-low patients. In addition, there was a significant difference in HR status between HER2 ultra-low and HER2-low patients (P = 0.001). The survival analysis showed that HER2 status had no effect on disease-free survival (DFS) in HER2-negative patients (all P > 0.05). However, regardless of HER2 status, HR+ patients had better DFS than HR- patients (P = 0.003). Cox multivariate analysis revealed that age (HR [95% CI] = 0.950 [0.928, 0.972], P < 0.001), HR status (HR [95% CI] = 3.342 [1.658, 6.736], P = 0.001), and postoperative endocrine therapy (HR [95% CI] = 0.048 [0.048, 0.023], P < 0.001) were important influencing factors of DFS in HER2-negative BC patients. CONCLUSION: HER2 ultra-low BC patients demonstrated distinct clinicopathological features from HER2-null and HER2-low tumors; while, HER2 status (null, ultra-low, or low) had no prognostic value in these HER2-negative BC population. Consistent with the published literature, HR status was an independent prognostic factor for DFS in HER2-negative BC patients.

Mechanistic Insight into Acceptorless Dehydrogenation of Methanol to Syngas Catalyzed by MACHO-Type Ruthenium and Manganese Complexes: A DFT Study.

The acceptorless dehydrogenation of methanol to produce carbon monoxide (CO) and dihydrogen (H2) mediated by MACHO-type 1-Ru and 1-Mn complexes was theoretically investigated via density functional theory calculations. The 1-Ru-catalyzed process involves the formation of active species 4-Ru through a methanol-bridged H2 release pathway. Methanol dehydrogenation by 4-Ru yields formaldehyde and 1-Ru, followed by H2 release to regenerate 4-Ru (rate-determining step, ΔG‡ = 32.5 kcal/mol). Formaldehyde further reacts with methanol via nucleophilic attack of the MeO- ligand in the Ru complex (ΔG‡ = 9.6 kcal/mol), which is more favorable than the traditional methanol-to-formaldehyde nucleophilic attack (ΔG‡ = 33.8 kcal/mol) due to the higher nucleophilicity of MeO-. CO is ultimately produced through the methyl formate decarbonylation reaction. Accelerated H2 release in the early reaction stage compared to CO results from the initial methanol dehydrogenation and condensation of formaldehyde with methanol. In contrast, CO generation occurs later via methyl formate decarbonylation. The 1-Mn-catalyzed reaction has reduced efficiency compared to 1-Ru for the higher Gibbs energy barrier (ΔG‡ = 34.1 kcal/mol) of the rate-determining step. Excess NaOtBu promotes the reaction of CO and methanol, forming methyl formate, significantly reducing the CO/H2 ratio as the catalyst amount decreases. These findings deepen our understanding of the methanol-to-syngas transformation and can drive progress in this field.

Metal-free catalytic hydroboration of imine with pinacolborane using a pincer-type phosphorus compound: mechanistic insight and improvement of the reaction.

A mechanistic study of the catalytic hydroboration of imine using a pincer-type phosphorus compound 1NP was performed through the combination of DFT and DLPNO-CCSD(T) calculations. The reaction proceeds through a phosphorus-ligand cooperative catalytic cycle, where the phosphorus center and triamide ligand work in a synergistic manner. First, the pinB-H bond activation by 1NP occurs through the cooperative functions of the phosphorus center and the triamide ligand, leading to a phosphorus-hydride intermediate 2NP. This is the rate-determining step, with the Gibbs energy barrier and Gibbs reaction energy of 25.3 and -17.0 kcal mol-1, respectively. Subsequently, the hydroboration of phenylmethanimine takes place through a concerted transition state through the cooperative function of the phosphorus center and the triamide ligand. It leads to the final hydroborated product 4 with the regeneration of 1NP. Our computational results reveal that the experimentally isolated intermediate 3NP is a resting state of the reaction. It is formed through the B-N bond activation of 4 by 1NP, rather than via the insertion of the CN double bond of phenylmethanimine into the P-H bond of 2NP. However, this side reaction can be suppressed by utilizing a planar phosphorus compound AcrDipp-1NP as the catalyst, which features steric-demanding substituents on the chelated N atom of the ligand.