Oriented lateral growth of two-dimensional materials on c-plane sapphire.

Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) represent the ultimate thickness for scaling down channel materials. They provide a tantalizing solution to push the limit of semiconductor technology nodes in the sub-1 nm range. One key challenge with 2D semiconducting TMD channel materials is to achieve large-scale batch growth on insulating substrates of single crystals with spatial homogeneity and compelling electrical properties. Recent studies have claimed the epitaxy growth of wafer-scale, single-crystal 2D TMDs on a c-plane sapphire substrate with deliberately engineered off-cut angles. It has been postulated that exposed step edges break the energy degeneracy of nucleation and thus drive the seamless stitching of mono-oriented flakes. Here we show that a more dominant factor should be considered: in particular, the interaction of 2D TMD grains with the exposed oxygen-aluminium atomic plane establishes an energy-minimized 2D TMD-sapphire configuration. Reconstructing the surfaces of c-plane sapphire substrates to only a single type of atomic plane (plane symmetry) already guarantees the single-crystal epitaxy of monolayer TMDs without the aid of step edges. Electrical results evidence the structural uniformity of the monolayers. Our findings elucidate a long-standing question that curbs the wafer-scale batch epitaxy of 2D TMD single crystals-an important step towards using 2D materials for future electronics. Experiments extended to perovskite materials also support the argument that the interaction with sapphire atomic surfaces is more dominant than step-edge docking.

A Robust Predefined-Time Convergence Zeroing Neural Network for Dynamic Matrix Inversion.

As a classical and effective method for solving various time-varying problems, the zeroing neural network (ZNN) is widely applied in the scientific and industrial realms. In plentiful studies on the ZNN model, its robustness and convergence have been two essential criteria to evaluate the quality of the model. Improvements in the ZNN model have been focused on its convergence speed; however, the adjustability of its convergence speed has been neglected in most prior works, which restricts its extensive promotion in practical application. Considering the above-mentioned issue, a well-designed activation function (WDAF) is designed. Based on the WDAF, a robust predefined-time convergence ZNN (RPTCZNN) model with adjustable convergence speed is proposed to solve the dynamic matrix inversion problem. In addition, the upper bound of the RPTCZNN model's convergence time is theoretically validated by strict mathematical analysis in a noiseless and noisy environment. Finally, several simulation experiments of the proposed model are conducted to find solutions of dynamic matrix inversion with different dimensions. Moreover, the realization of the tracking control of the robotic manipulator further illustrates the model's superior convergence and robustness.

A robust zeroing neural network and its applications to dynamic complex matrix equation solving and robotic manipulator trajectory tracking.

Dynamic complex matrix equation (DCME) is frequently encountered in the fields of mathematics and industry, and numerous recurrent neural network (RNN) models have been reported to effectively find the solution of DCME in no noise environment. However, noises are unavoidable in reality, and dynamic systems must be affected by noises. Thus, the invention of anti-noise neural network models becomes increasingly important to address this issue. By introducing a new activation function (NAF), a robust zeroing neural network (RZNN) model for solving DCME in noisy-polluted environment is proposed and investigated in this paper. The robustness and convergence of the proposed RZNN model are proved by strict mathematical proof and verified by comparative numerical simulation results. Furthermore, the proposed RZNN model is applied to manipulator trajectory tracking control, and it completes the trajectory tracking task successfully, which further validates its practical applied prospects.

Synthesis, herbicidal activity and soil degradation of novel 5-substituted sulfonylureas as AHAS inhibitors.

BACKGROUND: Chlorsulfuron, metsulfuron-methyl and ethametsulfuron can damage sensitive crops in rotation pattern as a result of their long persistence in soil. To explore novel sulfonylurea (SU) herbicides with favorable soil degradation rates, four series of SUs were synthesized through a structure-based drug design (SBDD) strategy. RESULTS: The target compounds, especially Ia, Id and Ie, exhibited prospective herbicidal activity against dicotyledon oil seed rape (Brassica campestris), amaranth (Amaranthus retroflexus), monocotyledon barnyard grass (Echinochloa crusgalli) and crab grass (Digitaria sanguinalis) at a concentration of 15 a.i. g ha-1 . Additionally, Ia, Id and Ig displayed excellent inhibitory effects against AtAHAS, with Kapp i values of 59.1, 34.5 and 71.8 µm, respectively, which were much lower than that of chlorsulfuron at 149.4 µm. The π-π stack and H-bonds between the Ia conformation and AtAHAS in the molecular docking results confirmed the series of compounds to be conventional AHAS inhibitors. In alkaline soil (pH = 8.46), compounds Ia-Ig revealed various degrees of acceleration in the degradation rate compared with chlorsulfuron. Besides, compound Ia showed considerable wheat and corn safety under postemergence at the concentration of 30, 60 and even 120 a.i. g ha-1 . CONCLUSION: Overall, based on the synthetic procedure, herbicidal activity, soil degradation and crop safety, the Ia sulfonylureas series were chosen to be investigated as prospective AHAS inhibitors. The 5-dimethylamino group on SUs accelerated the degradation rate at different levels in alkaline soils which seems to be controllable in conventional cropping systems in their further application. © 2022 Society of Chemical Industry.

Comparison of Auxin and Cytokinins Concentrations, and the Structure of Bacterial Community between Host Twigs and Lithosaphonecrus arcoverticus Galls.

Insect galls are the abnormal growth of plant tissues induced by a wide variety of galling insects and characterized by high concentrations of auxins and cytokinins. It remains unclear whether the auxins and cytokinins affect the bacterial community structure of insect galls. We determined the concentrations of indoleacetic acid (IAA) as an example of auxin, trans-zeatin riboside (tZR) and isopentenyladenine (iP) as cytokinins in Lithosaphonecrus arcoverticus (Hymenoptera: Cynipidae) galls and the galled twigs of Lithocarpus glaber (Fagaceae) using liquid chromatography-tandem mass spectrometry. Moreover, for the first time, we compared the bacterial community structure of L. arcoverticus galls and galled twigs by high-throughput sequencing, and calculated the Spearman correlation and associated degree of significance between the IAA, tZR and iP concentrations and the bacterial community structure. Our results indicated the concentrations of IAA, tZR and iP were higher in L. arcoverticus galls than in galled twigs, and positively correlated with the bacterial community structure of L. arcoverticus galls. We suggest the high concentrations of IAA, tZR and iP may affect the bacterial community structure of L. arcoverticus galls.

The Diversity and Dynamics of Fungi in Dryocosmus kuriphilus Community.

Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is a gall wasp that induces insect galls on chestnut trees and results in massive yield losses worldwide. Fungi can cause the necrosis of chestnut trees and the death of gall wasps. The aim of this research was to investigate the potential role of D. kuriphilus in the transmission of fungi. We sequenced the ribosomal RNA internal transcribed spacer region 1 of fungi in D. kuriphilus adults, associated insect galls and the galled twigs of Castanea mollissima, using high-throughput sequencing. We compared the species richness, α-diversity and community structure of fungi in D. kuriphilus adults, insect galls and the galled twigs. We provide the first evidence that D. kuriphilus adults shared most fungal species with associated insect galls and the galled twigs, and were dominated by Botryosphaeria sp., Aspergillus sp. and Diaporthe sp. We suggest D. kuriphilus adults may be potential vectors of plant pathogens and may facilitate the transmission of fungi between chestnut trees. Furthermore, the fungi may horizontally transmit among D. kuriphilus adults, associated insect galls and the galled twigs.

Self-emitted surface corrugations in dynamic fracture of silicon single crystal.

When a dynamic crack front travels through material heterogeneities, elastic waves are emitted, which perturb the crack and change the morphology of the fracture surface. For asperity-free crystalline materials, crack propagation along preferential cleavage planes is expected to present a smooth crack front and form a mirror-like fracture surface. Surprisingly, we show here that in single crystalline silicon without material asperities, the crack front presents a local kink during high-speed crack propagation. Meanwhile, local oscillations of the crack front, which can move along the crack front, emerge at the front kink position and generate periodic fracture surface corrugations. They grow from angstrom amplitude to a few hundred nanometers and propagate with a long lifetime at a frequency-dependent speed, while keeping a scale-independent shape. In particular, the local front oscillations collide in a particle-like manner rather than proceeding with a linear superposition upon interaction, which presents the characteristic of solitary waves. We propose that such a propagating mode of the crack front, which results from the fracture energy fluctuation at a critical crack speed in the silicon crystal, can be considered as nonlinear elastic waves that we call "corrugation waves."

Velocity correlated crack front and surface marks in single crystalline silicon.

Single crystalline silicon fractures on low-energy cleavage planes such as (111) and (110). The crack propagation cannot accurately be predicted by linear elastic fracture mechanics since it does not account for small scale and inelastic phenomena such as atomic lattice trapping. Here we show that, under pure bending load, (110) cleavage in silicon single crystal rapidly accelerates to 3700 m/s without crack path deviation or crack branching, contrasting previous observations. We highlight that the crack front shape involves strong velocity dependence and presents a curvature jump during very high-speed crack growth. In addition, we observe special marks-a kind of periodic surface undulation-that exclusively arise on the rapid fracture surfaces, and we suggest that they are front wave traces resulting from an intrinsic local velocity fluctuation. This finding gives insight to the wavy nature of the crack front in the absence of material asperity.

The versatile functions of LRR-only proteins in mollusk Chlamys farreri.

Leucine-rich repeat (LRR)-only proteins are involved in the innate immune responses as they mediate protein-ligand interactions. In the present study, three novel LRR-only proteins, CfLRRop-4, CfLRRop-5 and CfLRRop-6, were identified and characterized from Zhikong scallop Chlamys farreri. They all contained LRR motifs with consensus signature sequences of LxxLxLxxNxL or LxxLxLxxCxxL. All the mRNA transcripts of three CfLRRops were high abundant in hepatopancreas, gills and gonads, and their mRNA transcripts in hemocytes could respond to the stimulations of different microbes, including Vibrio anguillarum, Micrococcus luteus and Pichia pastoris. These three CfLRRops exhibited similar ligand binding and recognition characteristics as Toll-like receptors (TLRs) and NOD-like receptors (NLRs). The immune effectors, including tumor necrosis factor α, superoxide dismutase, catalase and lysozyme, varied significantly after the scallops were stimulated by recombinant LRR-only proteins. All these results indicated that LRR-only proteins are functionally differentiated and exhibit different immunomodulation activities on various downstream immune effectors.

Evodiamine Induces Apoptosis and Inhibits Migration of HCT-116 Human Colorectal Cancer Cells.

Evodiamine (EVO) exhibits strong anti-cancer effects. However, the effect of EVO on the human colorectal cancer cell line HCT-116 has not been explored in detail, and its underlying molecular mechanisms remain unknown. In the present study, cell viability was assessed by Cell Counting Kit-8 (CCK-8). Cell cycle and apoptosis were measured by flow cytometry, and morphological changes in the nucleus were examined by fluorescence microscopy and Hoechst staining. Cell motility was detected by Transwell assay. ELISA was used to assess the protein levels of autocrine motility factor (AMF) in the cell supernatant, and protein expression was determined by Western blotting. Our results showed that EVO inhibited the proliferation of HCT-116 cells, caused accumulation of cells in S and G2/M phases, and reduced the levels of the secreted form of AMF. The protein levels of tumor suppressor protein (p53), Bcl-2 Associated X protein (Bax), B cell CLL/lymphoma-2 (Bcl-2), phosphoglucose isomerase (PGI), phosphorylated signal transducers and activators of transcription 3 (p-STAT3) and matrix metalloproteinase 3 (MMP3) were altered in cells treated with EVO. Taken together, our results suggest that EVO modulates the activity of the p53 signaling pathway to induce apoptosis and downregulate MMP3 expression by inactivating the JAK2/STAT3 pathway through the downregulation of PGI to inhibit migration of HCT-116 human colorectal cancer cells.

Cigarette smoke extract induces apoptosis of rat alveolar Type II cells via the PLTP/TGF-ß1/Smad2 pathway.

Apoptosis of alveolar epithelial cells has been implicated in the pathogenesis of acute lung injury. Phospholipid transfer protein (PLTP) may play a role in apoptosis. In the present study, the effect of the novel function of PLTP in cigarette smoke extract (CSE)-induced apoptosis of alveolar epithelial cells and the possible mechanism were examined. Male Wistar rats were exposed to air and cigarette smoke (n=10/exposure) for 6h/day on 3 consecutive days, then the lungs were sectioned and examined. To investigate effects on alveolar epithelial cells, rat alveolar epithelial cells (RLE-6TN) were treated with different concentrations of CSE for various times. siRNA for PLTP was transfected into cells and an inhibitor of the transforming growth factor-ß1 (TGF-ß1) type I receptor was administered prior to CSE exposure. Apoptosis was measured, and mRNA expression of PLTP and TGF-ß1 and protein levels of PLTP, TGF-ß1, p-Smad2 and cleaved caspase-3 were analyzed. The results showed that apoptosis, as well as expression of PLTP, TGF-ß1, p-Smad2 and cleaved caspase-3 were all significantly increased after CSE stimulation (P<0.05). Furthermore, the expression of TGF-ß1, p-Smad2 and cleaved caspase-3 induced by CSE could be partly abrogated by knockdown of PLTP. The expression of PLTP showed no significant change as a result of TGF-ß1 receptor inhibition, while cleaved caspase-3 showed a remarkable reduction. PLTP may act as an upstream signal molecule of the TGF-ß1/Smad2 pathway and is likely to be involved in CSE-induced apoptosis of alveolar epithelial cells.

Induction of Apoptosis in Human Leukemic Cell Lines by Diallyl Disulfide via Modulation of EGFR/ERK/PKM2 Signaling Pathways.

BACKGROUND: Diallyl disulfide (DADS) may exert potent anticancer action both in vitro and in vivo. Although its effects on cancer are significant, the underlying mechanisms remain unknown. In this study, we sought to elucidate possible links between DADS and pyruvate kinase (PKM2). MATERIALS AND METHODS: KG1α, a leukemia cell line highly expressing PKM2 was used with a cell counting kit (CCK)-8 and flow cytometry (FCM) to investigate the effects of DADS. Relationships between PKM2 and DADS associated with phosphorylation of EGFR, ERK1/2 and MEK, were assessed by western blot analysis. RESULTS: In KG1α cells highly expressing PKM2, we found that DADS could affect proliferation, apoptosis and EGFR/ERK/PKM2 signaling pathways, abrogating EGF-induced nuclear accumulation of PKM2. CONCLUSIONS: These results suggested that DADS suppressed the proliferation of KG1α cells, providing evidence that its proapoptotic effects are mediated through the inhibition of EGFR/ERK/PKM2 signaling pathways.

Effect of trichostatin A on anti HepG2 liver carcinoma cells: inhibition of HDAC activity and activation of Wnt/ß-Catenin signaling.

PURPOSE: To investigate the effect of deacetylase inhibitory trichostatin A (TSA) on anti HepG2 liver carcinoma cells and explore the underlying mechanisms. MATERIALS AND METHODS: HepG2 cells exposed to different concentrations of TSA for 24, 48, or 72h were examined for cell growth inhibition using CCK8, changes in cell cycle distribution with flow cytometry, cell apoptosis with annexin V-FTIC/PI double staining, and cell morphology changes under an inverted microscope. Expression of ß-catenin, HDAC1, HDAC3, H3K9, CyclinD1 and Bax proteins was tested by Western blotting. Gene expression for ß-catenin, HDAC1and HDAC3 was tested by q-PCR. ß-Catenin and H3K9 proteins were also tested by immunofluorescence. Activity of Renilla luciferase (pTCF/LEF-luc) was assessed using the Luciferase Reporter Assay system reagent. The activity of total HDACs was detected with a HDACs colorimetric kit. RESULTS: Exposure to TSA caused significant dose-and time-dependent inhibition of HepG2 cell proliferation (p<0.05) and resulted in increased cell percentages in G0/ G1 and G2/M phases and decrease in the S phase. The apoptotic index in the control group was 6.22±0.25%, which increased to 7.17±0.20% and 18.1±0.42% in the treatment group. Exposure to 250 and 500nmol/L TSA also caused cell morphology changes with numerous floating cells. Expression of ß-catenin, H3K9and Bax proteins was significantly increased, expression levels of CyclinD1, HDAC1, HDAC3 were decreased. Expression of ß-catenin at the genetic level was significantly increased, with no significant difference in HDAC1and HDAC3 genes. In the cytoplasm, expression of ß-catenin fluorescence protein was not obvious changed and in the nucleus, small amounts of green fluorescence were observed. H3K9 fluorescence protein were increased. Expression levels of the transcription factor TCF werealso increased in HepG2 cells following induction by TSA, whikle the activity of total HDACs was decreased. CONCLUSIONS: TSA inhibits HDAC activity, promotes histone acetylation, and activates Wnt/ß-catenin signaling to inhibit proliferation of HepG2 cell, arrest cell cycling and induce apoptosis.

Zinc on cell proliferation and oifferentiation / 国际生物医学工程杂志

Zinc is essential for cell proliferation and differentiation,especially for the regulation of DNA synthesis and mitosis.On the molecular level,it is a structural constituent of a great number of proteins including enzymes of cellular signaling pathways and transcription factors.Zinc can modulate cellular signal recognition,second messenger metabolism,protein kinase and protein phosphatase activities.It may stimulate or inhibit activities of transcription factors,and it may as well be used as a second messenger involved in cell signaling regulation.