Investigation of the topography-dependent current in conductive AFM and the calibration method

The topography and the electrical properties of materials are two crucial characteristics in determining their functionalities. Conductive atomic force microscopy (CAFM) is widely recognized for its ability to independently measure the topology and conductivity of the sample surface. The increasing trend towards miniaturization in electrical devices and sensors has led to an urgent demand for enhancing the accuracy of CAFM characterization. However, the sample's topography may affect the current measured by CAFM, leading to an inaccurate estimation of the sample's conductivity. Herein, we investigated the existence of topography-dependent current that originates from changes in capacitance between the probe and sample in CAFM testing. A linear correlation between the current and topography has been established using both experimental and theoretical methods. A calibration method based on this linear correlation has been proposed to eliminate the current error induced by the uneven surface of both insulators and conductors. This work will yield substantial advantages for research requiring high-precision CAFM testing.Comment: Corrected typo

BiERL: A Meta Evolutionary Reinforcement Learning Framework via Bilevel Optimization

Evolutionary reinforcement learning (ERL) algorithms recently raise attention in tackling complex reinforcement learning (RL) problems due to high parallelism, while they are prone to insufficient exploration or model collapse without carefully tuning hyperparameters (aka meta-parameters). In the paper, we propose a general meta ERL framework via bilevel optimization (BiERL) to jointly update hyperparameters in parallel to training the ERL model within a single agent, which relieves the need for prior domain knowledge or costly optimization procedure before model deployment. We design an elegant meta-level architecture that embeds the inner-level's evolving experience into an informative population representation and introduce a simple and feasible evaluation of the meta-level fitness function to facilitate learning efficiency. We perform extensive experiments in MuJoCo and Box2D tasks to verify that as a general framework, BiERL outperforms various baselines and consistently improves the learning performance for a diversity of ERL algorithms.Comment: Published as a conference paper at European Conference on Artificial Intelligence (ECAI) 202

Comparative analysis of long noncoding RNAs in angiosperms and characterization of long noncoding RNAs in response to heat stress in Chinese cabbage

Long noncoding RNAs (lncRNAs) are widely present in different species and play critical roles in response to abiotic stresses. However, the functions of lncRNAs in Chinese cabbage under heat stress remain unknown. Here, we first conducted a global comparative analysis of 247,242 lncRNAs among 37 species. The results indicated that lncRNAs were poorly conserved among different species, and only 960 lncRNAs were homologous to 524 miRNA precursors. We then carried out lncRNA sequencing for a genome-wide analysis of lncRNAs and their target genes in Chinese cabbage at different stages of heat treatment. In total, 18,253 lncRNAs were identified, of which 1229 differentially expressed (DE) lncRNAs were characterized as being heat-responsive. The ceRNA network revealed that 38 lncRNAs, 16 miRNAs, and 167 mRNAs were involved in the heat response in Chinese cabbage. Combined analysis of the cis- and trans-regulated genes indicated that the targets of DE lncRNAs were significantly enriched in the “protein processing in endoplasmic reticulum” and “plant hormone signal transduction” pathways. Furthermore, the majority of HSP and PYL genes involved in these two pathways exhibited similar expression patterns and responded to heat stress rapidly. Based on the networks of DE lncRNA-mRNAs, 29 and 22 lncRNAs were found to interact with HSP and PYL genes, respectively. Finally, the expression of several critical lncRNAs and their targets was verified by qRT-PCR. Overall, we conducted a comparative analysis of lncRNAs among 37 species and performed a comprehensive analysis of lncRNAs in Chinese cabbage. Our findings expand the knowledge of lncRNAs involved in the heat stress response in Chinese cabbage, and the identified lncRNAs provide an abundance of resources for future comparative and functional studies

Inactivation of a Novel FGF23 Regulator, FAM20C, Leads to Hypophosphatemic Rickets in Mice

Family with sequence similarity 20,-member C (FAM20C) is highly expressed in the mineralized tissues of mammals. Genetic studies showed that the loss-of-function mutations in FAM20C were associated with human lethal osteosclerotic bone dysplasia (Raine Syndrome), implying an inhibitory role of this molecule in bone formation. However, in vitro gain- and loss-of-function studies suggested that FAM20C promotes the differentiation and mineralization of mouse mesenchymal cells and odontoblasts. Recently, we generated Fam20c conditional knockout (cKO) mice in which Fam20c was globally inactivated (by crossbreeding with Sox2-Cre mice) or inactivated specifically in the mineralized tissues (by crossbreeding with 3.6 kb Col 1a1-Cre mice). Fam20c transgenic mice were also generated and crossbred with Fam20c cKO mice to introduce the transgene in the knockout background. In vitro gain- and loss-of-function were examined by adding recombinant FAM20C to MC3T3-E1 cells and by lentiviral shRNA–mediated knockdown of FAM20C in human and mouse osteogenic cell lines. Surprisingly, both the global and mineralized tissue-specific cKO mice developed hypophosphatemic rickets (but not osteosclerosis), along with a significant downregulation of osteoblast differentiation markers and a dramatic elevation of fibroblast growth factor 23 (FGF23) in the serum and bone. The mice expressing the Fam20c transgene in the wild-type background showed no abnormalities, while the expression of the Fam20c transgene fully rescued the skeletal defects in the cKO mice. Recombinant FAM20C promoted the differentiation and mineralization of MC3T3-E1 cells. Knockdown of FAM20C led to a remarkable downregulation of DMP1, along with a significant upregulation of FGF23 in both human and mouse osteogenic cell lines. These results indicate that FAM20C is a bone formation “promoter” but not an “inhibitor” in mouse osteogenesis. We conclude that FAM20C may regulate osteogenesis through its direct role in facilitating osteoblast differentiation and its systemic regulation of phosphate homeostasis via the mediation of FGF23

Characterization of the complete chloroplast genome of Saussurea integrifolia (Compositae)

The complete chloroplast genome sequence of Saussurea integrifolia, a flowering plant occurring in Hengduan Mountains with high altitudes, is determined in this study. The plastome is 152,584 bp in length, with one large single-copy region of 83,497 bp, one small single-copy region of 18,646 bp, and two inverted repeat (IR) regions of 25,221 bp. It contains 123 genes, including 86 protein-coding genes, 8 ribosomal RNA, and 36 transfer RNA. Phylogenetic tree shows that this species is a sister to Arctium lappa. The published plastome within Saussurea provides significant insight for elucidating the phylogenetic relationship of taxa within tribe Compositae

The deformation, cracking and failure behavior of lithological layered coal disk in Brazilian experiment

The cracking characterization of lithological layered coal disk under tensile stress is important for hydraulic fracturing in coal seam gas recovery. With digital image correlation and acoustic emission techniques, the cracking and fracture pattern of layered coal disk in Brazilian test were investigated considering different anisotropy angle between axial load and stratification plane and loading rate. The results show that both tensile and shear cracks developed in coal disk, and the crack initiation deviated from the center for most coal samples, closely related to stratification orientation, but irrespective of loading rate. The anisotropy angle in a range of 0°–45° favors the shear slip along stratification, leading to shear stick slip in both pre- and post-peak stages. However, the tensile cracks dominate in the early loading stage and then shear cracks start to be significant after the tensile cracks intersect with stratification plane. The stress state changed when the tensile cracks intersect with stratification plane, making crack deviate from the original propagation path. In addition, the tensile strength is related to the anisotropy angle. The maximum tensile strength occurs when the anisotropy angle α = 0° and the minimum tensile strength appears when the anisotropy angle α = 30°

Visible-Light-Driven Reductive Carboarylation of Styrenes with CO2 and Aryl Halides

The first example of visible-light-driven reductive carboarylation of styrenes with CO2 and aryl halides in a regioselective manner has been achieved. A broad range of aryl iodides and bromides were compatible with this reaction. Moreover, pyridyl halides, alkyl halides and even aryl chlorides were also viable with this method. These findings may stimulate the exploration of novel visible-light-driven Meerwein arylation-addition reactions with user-friendly aryl halides as the radical sources and the photocatalytic utilization of CO2.</sub