Because the surface-to-volume ratio of quasi-two-dimensional materials is extremely high, understanding their surface characteristics is crucial for practically controlling their intrinsic properties ...and fabricating p-type and n-type layered semiconductors. Van der Waals crystals are expected to have an inert surface because of the absence of dangling bonds. However, here we show that the surface of high-quality synthesized molybdenum disulfide (MoS2) is a major n-doping source. The surface electron concentration of MoS2 is nearly four orders of magnitude higher than that of its inner bulk. Substantial thickness-dependent conductivity in MoS2 nanoflakes was observed. The transfer length method suggested the current transport in MoS2 following a two-dimensional behavior rather than the conventional three-dimensional mode. Scanning tunneling microscopy and angle-resolved photoemission spectroscopy measurements confirmed the presence of surface electron accumulation in this layered material. Notably, the in situ-cleaved surface exhibited a nearly intrinsic state without electron accumulation.
We report a simple chemical conversion approach to fabricate ZnO/ZnS core/shell nanorods and various metal sulfide nanotubes such as ZnS, Ag2S, CuS, PbS, and Bi2S3. The formation mechanisms of the ...ZnO/ZnS core/shell nanorods and ZnS nanotubes are due to the sulfidation conversion and the Kirkendall effect, respectively, in a low-temperature hydrothermal growth through the reaction of ZnO nanowires and thioacetamide. The successful chemical conversion of the ZnS nanotubes into the other metal sulfide nanotubes is to utilize the large difference in solubility between ZnS and the other metal sulfides for the effective transformation. In addition to the perfect maintenance of the morphology after conversion, we have shown that the yielded metal sulfide nanostructures possess good crystalline qualities with high optical and sensing performances. The present chemical conversion technique is expected to be employed in a broad range of applications to fabricate innovative semiconductor core/shell and hollow structures with various compositions and shapes for unique properties.
Ammonia intercalated flower-like MoS2 electrocatalyst film assembled by vertical orientated ultrathin nanosheet on graphite sheethas been successfully synthesized using one-step hydrothermal method. ...In this strategy, ammonia can effectively insert into the parallel plane of the MoS2 nanosheets, leading to the expansion of lattice and phase transfer from 2H to 1T, generating more active unsaturated sulfur atoms. The flower-like ammoniated MoS2 electrocatalysts with more active sites and large surface area exhibited excellent HER activity with a small Tafel slope and low onset overpotential, resulting a great enhancement in hydrogen evolution. The high efficient activity and recyclable utilization, as well as large-scale, indicate that it is a very promising electrocatalyst to replace Pt in industry application.
N-acetyltransferase 10 (NAT10) is the key enzyme for N4-acetylcytidine (ac4C) modification of mRNA, which participates in various cellular processes and is related to many diseases. Here, we explore ...the relationships among osteoblast differentiation, NAT10, and ac4C, and we found that NAT0 expression and the ac4C level of total RNA were decreased in the bone tissues of bilateral ovariectomized (OVX) mice and osteoporosis patients. Adenoviruses overexpressing NAT10 reversed bone loss, and Remodelin, an NAT10 inhibitor, enhanced the loss of bone mass in OVX mice. Moreover, bone marrow-derived mesenchymal stem cells (BMSCs) with low-level ac4C modification formed fewer calcium nodules in vitro with NAT10 silencing, whereas BMSCs with high-level ac4C modification formed more calcium nodules with NAT10 overexpression. Moreover, we demonstrated that the ac4C level of runt-related transcription factor 2 (RUNX2) mRNA was increased after BMSCs were cultured in osteogenic medium (OM) and decreased after NAT10 silencing. The RUNX2 mRNA half-life and protein expression decreased after silencing NAT10 in BMSCs. Therefore, NAT10-based ac4C modification promotes the osteogenic differentiation of BMSCs by regulating the RUNX2 ac4C level. Because abnormal levels of NAT10 are probably one of the mechanisms responsible for osteoporosis, NAT10 is a new potential therapeutic target for this disease.
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NAT10 catalyzes the addition of ac4C to RUNX2 mRNA, which increases the half-life of RUNX2 mRNA and promotes osteogenic differentiation of BMSCs. Moreover, overexpression of NAT10 with adenovirus reversed the bone loss in OVX mice. These results indicate that NAT10 may be a new potential therapeutic target for osteoporosis.
Abstract
Epiphytes offer an appealing framework to disentangle the contributions of chance, biotic and abiotic drivers of species distributions. In the context of the stress‐gradient theory, we test ...the hypotheses that (i) deterministic (
i.e.
, non‐random) factors play an increasing role in communities from young to old trees, (ii) negative biotic interactions increase on older trees and towards the tree base, and (iii) positive interactions show the reverse pattern.
Bryophyte species distributions and abiotic conditions were recorded on a 1.1 ha tropical rainforest canopy crane site. We analysed co‐occurrence patterns in a niche modelling framework to disentangle the roles of chance, abiotic factors and putative biotic interactions among species pairs.
76% of species pairs resulted from chance. Abiotic factors explained 78% of non‐randomly associated species pairs, and co‐occurrences prevailed over non‐coincidences in the remaining species pairs. Positive and negative interactions mostly involved species pairs from the same
versus
different communities (mosses
versus
liverworts) and life forms, respectively. There was an increase in randomly associated pairs from large to small trees. No increase in negative interactions from young to old trees or from the canopy to the base was observed.
Our results suggest that epiphytic bryophyte community composition is primarily driven by environmental filtering, whose importance increases with niche complexity and diversity. Biotic interactions play a secondary role, with a very marginal contribution of competitive exclusion. Biotic interactions vary among communities (mosses
versus
liverworts) and life forms, facilitation prevailing among species from the same community and life form, and competition among species from different communities and life forms.
Purpose
To investigate the potential candidate microRNA (miRNA) biomarkers for the clinical diagnosis, classification, and prognosis of gastric cancer (GC).
Methods
We use bioinformatics overlapping ...subclasses analysis to find the tumor grade and lymphatic metastasis-related GC specific miRNAs from the Cancer Genome Atlas (TCGA) database. Then, we further investigated these GC specific miRNAs distributions in different GC clinical features and their correlations overall survival on the basis of GC patients’ information and their related RNA sequencing profile from TCGA. Finally, we randomly selected some of key miRNAs use qRT-PCR to confirm the reliability and validity.
Results
22 GC specific key miRNAs were identified (Fold-change >2,
P
< 0.05), 11 of them were discriminatively expressed with tumor size, grade, TNM stage and lymphatic metastasis (
P
< 0.05). In addition, nine miRNAs (miR-196b-5p, miR-135b-5p, miR-183-5p, miR-182-5p, miR-133a-3p, miR-486-5p, miR-144-5p, miR-129-5p and miR-145-5p) were found to be significantly associated with overall survival (log-rank
P
< 0.05). Finally, four key miRNAs (miR-183-5p, miR-486-5p, miR-30c-2-3p and miR-133a-3p) were randomly selected to validation and their expression levels in 53 newly diagnosed GC patients by qRT-PCR. Results showed that the fold-changes between TCGA and qRT-PCR were 100 % in agreement. We also found miR-183-5p and miR-486-5p were significantly correlated with tumor TNM stage (
P
< 0.05), and miR-30c-2-3p and miR-133a-3p were associated with tumor differentiation degree and lymph-node metastasis (
P
< 0.05). These verified miRNAs clinically relevant, and the bioinformatics analysis results were almost the same.
Conclusion
These key miRNAs may functions as potential candidate biomarkers for the clinical diagnosis, classification and prognosis for GC.
The cast-grown monocrystalline-like silicon (mono-like Si) technology has been reactivated recently for the manufacture of high-efficiency solar cells at low cost. In this paper, we have provided a ...progressive research, both experimentally and theoretically, to improve the efficiency of mono-like Si passivated emitter and rear cells (PERCs) through production lines. By employing rear surface passivation of AlOx/triple-SiNx:H layers, the average efficiency has increased to 21.87% with a champion efficiency of 22.32% from the standard mono-like Si PERCs of 21.72% efficiency with AlOx capped with double-SiNx:H layers. We have further optimized the rear electrode contact patterns and introduced the selective emitter (SE) technology, yielding an absolute efficiency improvement of 0.19% and 0.26%, respectively. Integrating all approaches of the triple-SiNx:H, rear contact pattern optimization and SE technology, we have demonstrated that the mono-like Si PERCs can reach the average efficiency of 22.2% with a maximum efficiency of 22.5%, similar to the current Czochralski monocrystalline Si counterparts.
In this study, the detonation diffraction and re-initiation processes around a single cuboid were studied experimentally. Experiments were performed in a 6-m-long duct with a cross section of 112 mm ...× 112 mm filled with stoichiometric methane–oxygen mixtures at initial pressures between 10 and 30 kPa. A cuboid was placed in the duct to form two perpendicular passages between the cuboid and the walls. Soot foils fixed on the side wall and bottom wall were used to characterize the cellular structure evolution process, from which the diffraction and re-initiation behavior of a detonation could be analyzed. The effects of the spacing between the cuboid and the top wall (
δ
) and the spacing between the cuboid and the side wall (
σ
) on diffraction and re-initiation were investigated systematically. It is shown that the diffraction and re-initiation of a detonation were influenced significantly by introducing a perpendicular channel. Compared with the unidirectional scenario, the boundary between the diffraction wave and the re-initiation region was not so sharp. Depending on the channel scale and mixtures sensitivity (or cell size,
λ
), two re-initiation modes could be observed. For more sensitive mixtures (
δ
/
λ
>
2
or
σ
/
λ
>
2
), an overdriven detonation occurs first. The overdriven detonation propagates toward the edge, generating a secondary overdriven detonation near the wall through detonation reflection. The new one propagates forward and decays to a steady-state detonation. On the other hand, only one overdriven detonation occurs for less sensitive mixtures. For a given channel width, it was demonstrated that the diffraction area could be narrowed as the perpendicular channel width was increased. The inverse feedback mechanism between the two perpendicular diffraction waves was analyzed.
The bifacial p-type silicon (p-Si) passivated emitter and rear cells (PERCs) are predicted to dominate the industrial bifacial solar cells. In this work, we have investigated the impact of different ...rear surface morphologies on the electrical performance of bifacial PERCs with both five-busbar (5BB) and nine-busbar (9BB) grid design. The passivation and optical properties with differing rear surfaces are evaluated on semi-device structures. The depth of local aluminum back surface field is hardly affected by the rear surface morphology. The calculated efficiency loss analysis indicates that the negative electrical impact with enlarged rear surface area is more serious for rear side than that of front side. The batch conversion efficiency of 9BB bifacial PERCs increases by 0.2%–0.3% comparing to 5BB ones depending on the rear surface roughness. Consequently, a highest front-side average efficiency of 22.57%, with a champion efficiency of 22.75%, has been achieved for 9BB bifacial p-Si PERCs with a nearly planar rear surface. A highest bifaciality of 78.7% is realized for both 5BB and 9BB bifacial PERCs with the roughest rear surface. We have further simulated the relative enhancement of electric generation to compare the performance of bifacial PERCs in practical application.
•The impact of rear surface roughness on the performance of bifacial PERC solar cells with both 5BB and 9BB grid design.•The passivation and optical properties with different rear surface morphologies were evaluated.•The depth of Al-BSF was hardly influenced by rear surface morphology.•The negative electrical impact with enlarged surface area was more serious for rear side than front side.•A highest front-side average efficiency of 22.57% and a bifaciality of 78.7% were obtained.
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