Chemical Vapor Deposition of High-Quality Large-Sized MoS2 Crystals on Silicon Dioxide Substrates

Large???sized MoS2 crystals can be grown on SiO2/Si substrates via a two???stage chemical vapor deposition method. The maximum size of MoS2 crystals can be up to about 305 ??m. The growth method can be used to grow other transition metal dichalcogenide crystals and lateral heterojunctions. The electron mobility of the MoS2 crystals can reach ???30 cm2 V???1 s???1, which is comparable to those of exfoliated flakes.ope

China’s 10-year progress in DC gas-insulated equipment: From basic research to industry perspective

The construction of the future energy structure of China under the 2050 carbon-neutral vision requires compact direct current (DC) gas-insulation equipment as important nodes and solutions to support electric power transmission and distribution of long-distance and large-capacity. This paper reviews China's 10-year progress in DC gas-insulated equipment. Important progresses in basic research and industry perspective are presented, with related scientific issues and technical bottlenecks being discussed. The progress in DC gas-insulated equipment worldwide (Europe, Japan, America) is also reported briefly

Observer form of the hyperbolic type generalized Lorenz system and its use for chaos synchronization

summary:This paper shows that a large class of chaotic systems, introduced in [S. Čelikovský and G. Chen: Hyperbolic-type generalized Lorenz system and its canonical form. In: Proc. 15th Triennial World Congress of IFAC, Barcelona 2002, CD ROM], as the hyperbolic-type generalized Lorenz system, can be systematically used to generate synchronized chaotic oscillations. While the generalized Lorenz system unifies the famous Lorenz system and Chen’s system [G. Chen and T. Ueta: Yet another chaotic attractor. Internat. J. Bifur. Chaos 9 (1999)], the hyperbolic-type generalized Lorenz system is in some way complementary to it. Synchronization of two such systems is made through a scalar coupling signal based on nonlinear observer design using special change of coordinates to the so-called observer canonical form of the hyperbolic-type generalized Lorenz system. The properties of the suggested synchronization that make it attractive for the the secure encrypted communication application are discussed in detail. Theoretical results are supported by the computer simulations, showing viability of the suggested approach

Higher education and digital Economy: Analysis of their coupling coordination with the Yangtze River economic Belt in China as the example

Analyzing the coupling coordination interactions of higher education (HE) and digital economy (DE) to achieve sustainable growth is crucial. Thus, we constructed the coupling coordination interaction mechanism and the comprehensive evaluation system of the two subsystems to measure their coordination interactions; then, we processed the temporal-spatial analysis of the development status and the coupling coordination degree (CCD) in the case of China. Furthermore, we used the gray correlation model to determine the primary influencing factors and proposed differentiated policymaking suggestions. We found that: (1) the development status of higher education (HE-D) was more stable than that of the digital economy (DE-D), which showed a slight upward trend; besides, there were noticeable spatial differences for HE-D and DE-D. (2) The temporal changes of CCD were not noticeable. (3) Expenditure on research activities in HE and the number of patents were the significant factors affecting DE; the popularity rate of mobile phones and the number of employees in the DE industry were the significant factors affecting HE; besides, HE's output benefits and DE's input was more influential in the coordination relations. Furthermore, we also put forward targeted, specific, and differentiated policymaking suggestions, which can guide policymakers to formulate regional sustainable development policies

Differentiation of Human Induced-Pluripotent Stem Cells into Smooth-Muscle Cells: Two Novel Protocols.

Conventional protocols for differentiating human induced-pluripotent stem cells (hiPSCs) into smooth-muscle cells (SMCs) can be inefficient and generally fail to yield cells with a specific SMC phenotype (i.e., contractile or synthetic SMCs). Here, we present two novel hiPSC-SMC differentiation protocols that yield SMCs with predominantly contractile or synthetic phenotypes. Flow cytometry analyses of smooth-muscle actin (SMA) expression indicated that ~45% of the cells obtained with each protocol assumed an SMC phenotype, and that the populations could be purified to ~95% via metabolic selection. Assessments of cellular mRNA and/or protein levels indicated that SMA, myosin heavy chain II, collagen 1, calponin, transgelin, connexin 43, and vimentin expression in the SMCs obtained via the Contractile SMC protocol and in SMCs differentiated via a traditional protocol were similar, while SMCs produced via the Sythetic SMC protocol expressed less calponin, more collagen 1, and more connexin 43. Differences were also observed in functional assessments of the two SMC populations: the two-dimensional surface area of Contractile SMCs declined more extensively (to 12% versus 44% of original size) in response to carbachol treatment, while quantification of cell migration and proliferation were greater in Synthetic SMCs. Collectively, these data demonstrate that our novel differentiation protocols can efficiently generate SMCs from hiPSCs

Fractal Etching of Graphene

An anisotropic etching mode is commonly known for perfect crystalline materials, generally leading to simple Euclidean geometric patterns. This principle has also proved to apply to the etching of the thinnest crystalline material, graphene, resulting in hexagonal holes with zigzag edge structures. Here we demonstrate for the first time that the graphene etching mode can deviate significantly from simple anisotropic etching. Using an as-grown graphene film on a liquid copper surface as a model system, we show that the etched graphene pattern can be modulated from a simple hexagonal pattern to complex fractal geometric patterns with sixfold symmetry by varying the Ar/H₂ flow rate ratio. The etched fractal patterns are formed by the repeated construction of a basic identical motif, and the physical origin of the pattern formation is consistent with a diffusion-controlled process. The fractal etching mode of graphene presents an intriguing case for the fundamental study of material etching

hiPSC-SMC marker expression.

<p>(A) mRNA levels of the SMC markers alpha smooth-muscle actin 2 (αSMA-2), smooth muscle myosin heavy chain 11 (MHC-11), calponin (Calp), vascular-endothelial cadherin (VE-Cad), and transgelin (Tgln) were evaluated via quantitative RT-PCR and normalized to endogenous GAPDH mRNA levels (*p<0.01 vs Conventional or Contractile chiPSC-SMCs, ^†p<0.05 vs Conventional chiPSC-SMCs, ^†p<0.01 vs Contractile chiPSC-SMCs). (B) Smooth-muscle actin (SMA), collagen I (Col I), connexin 43 (Cnx 43), vimentin (Vmt), and calponin (Calp) protein expression (red) was detected via immunofluorescent staining in human aortic SMCs, in chiPSC-SMCs that were obtained via a conventional differentiation protocol, and in chiPSC-SMCs obtained via our Synthetic or Contractile hiPSC-SMC differentiation protocols; nuclei were counterstained with DAPI (blue) (bar = 100 μm).</p

Chronological summary of the hiPSC-SMC differentiation protocols.

<p>hiPSCs and ESCs were cultured in mTeSR^TM medium on Matrigel-coated plates, with daily medium changes, until confluent (~2 days); then, differentiation into mesodermal-lineage cells was initiated on Day 0 by culturing the cells with CHIR99021 and BMP-4 in RPMI1640 medium and 2% B27. Differentiation into Synthetic SMCs or Contractile SMCs began on Day 3. Synthetic SMCs were produced by culturing the cells with VEGF-A and FGFβ in RPMI1640 medium and 2% B27 minus insulin (B27^–) from Day 3 to Day 7, with VEGF-A and FGFβ in RPMI1640 and 2% B27 (with insulin) from Day 7 to Day 10, and with PDGFβ and TGFβ in RPMI1640 and 2% B27 from Day 10 to Day 14. Contractile SMCs were produced by culturing the cells with VEGF-A and FGFβ in RPMI1640 and 2% B27^– from Day 3 to Day 7, and with PDGFβ and TGFβ in RPMI1640 and 2% B27 from Day 7 to Day 14. Purification was performed by maintaining the differentiated cells in 4 mM lactate RPMI1640 metabolic medium for 4 to 6 days.</p

hiPSC-SMC functional assessments.

<p>(A) 4×10⁵ Synthetic or Contractile chiPSC-SMCs were cultured on gelatin-coated plates for 24 hours; then, the plate was scratched with a 200-μL pipette tip, and images of the scratched area were obtained 0 and 10 hours later. Migration was quantified by counting the number of cells that had migrated into the scratched area (*p<0.01). (B) 1×10⁶/mL Synthetic or Contractile chiPSC-SMCs were suspended in 100 μL of RPMI1640 and cultured in the presence of PDGFβ or TGFβ for 90 min; then, the solutions were serially diluted in half six times, and cell concentrations were evaluated via optical density measurements at 490 nm (*p<0.01). (C) 2×10⁵ Synthetic or Contractile chiPSC-SMCs were cultured on gelatin-coated plates for 24 hours; then, the cells were treated with carbachol to induce contraction, and images were obtained 0 and 5 min later. (D) Contraction was evaluated by calculating the mean cell surface area at each of the two time points (*p<0.01). (E) 1×10⁶ Synthetic or Contractile chiPSC-SMCs were suspended in a fibrinogen gel; then, the gels were cultured with aprotinin and Rho kinase inhibitor, and the surface area of the gels was measured 0 and 3 days later (*p<0.01).</p