Molecular dynamics simulation of graphene sinking during chemical vapor deposition growth on semi-molten Cu substrate

Copper foil is the most promising catalyst for the synthesis of large-area, high-quality monolayer graphene. Experimentally, it has been found that the Cu substrate is semi-molten at graphene growth temperatures. In this study, based on a self-developed C-Cu empirical potential and density functional theory (DFT) methods, we performed systematic molecular dynamics simulations to explore the stability of graphene nanostructures, i.e., carbon nanoclusters and graphene nanoribbons, on semi-molten Cu substrates. Many atomic details observed in the classical MD simulations agree well with those seen in DFT-MD simulations, confirming the high accuracy of the C-Cu potential. Depending on the size of the graphene island, two different sunken-modes are observed: (i) graphene island sinks into the first layer of the metal substrate and (ii) many metal atoms surround the graphene island. Further study reveals that the sinking graphene leads to the unidirectional alignment and seamless stitching of the graphene islands, which explains the growth of large single-crystal graphene on Cu foil. This study deepens our physical insights into the CVD growth of graphene on semi-molten Cu substrate with multiple experimental mysteries well explained and provides theoretic references for the controlled synthesis of large-area single-crystalline monolayer graphene

Pleistocene glacial cycle effects on the phylogeography of the Chinese endemic bat species, Myotis davidii

<p>Abstract</p> <p>Background</p> <p>Global climatic oscillations, glaciation cycles and the unique geographic topology of China have profoundly influenced species population distributions. In most species, contemporary distributions of populations cannot be fully understood, except in a historical context. Complex patterns of Pleistocene glaciations, as well as other physiographic changes have influenced the distribution of bat species in China. Until this study, there had been no phylogeographical research on <it>Myotis davidii</it>, an endemic Chinese bat. We used a combination of nuclear and mitochondrial DNA markers to investigate genetic diversity, population structure, and the demographic history of <it>M. davidii</it>. In particular, we compared patterns of genetic variation to glacial oscillations, topography, and environmental variation during the Pleistocene in an effort to explain current distributions in light of these historical processes.</p> <p>Results</p> <p><it>M. davidii </it>comprises three lineages (MEP, SWP and SH) based on the results of molecular variance analysis (AMOVA) and phylogenetic analyses. The results of a STRUCTURE analysis reveal multi-hierarchical population structure in <it>M. davidii</it>. Nuclear and mitochondrial genetic markers reveal different levels of gene flow among populations. In the case of mtDNA, populations adhere to an isolation-by-distance model, whereas the individual assignment test reveals considerable gene flow between populations. MDIV analysis indicate that the split of the MEP and SWP/SH lineages, and from the SWP and SH lineages were at 201 ka BP and 158 ka BP, respectively. The results of a mismatch distribution analysis and neutrality tests indicate a population expansion event at 79.17 ka BP and 69.12 ka BP in MEP and SWP, respectively.</p> <p>Conclusions</p> <p>The complex demographic history, discontinuous extant distribution of haplotypes, and multiple-hierarchy population structure of <it>M. davidii </it>appear associated with climatic oscillations, topography and eco-environmental variation of China. Additionally, the three regions are genetically differentiated from one another in the entire sample set. The degree of genetic differentiation, based on the analysis of mtDNA and nDNA, suggests a male-mediated gene flow among populations. Refuges were in the MEP, SH and the lower elevations of SWP regions. This study also provides insights for conservation management units (MEP, SWP and SH).</p

Surface-enhanced Raman Spectroscopy Facilitates the Detection of Microplastics &lt; 1 μm in the Environment

Micro- and nanoplastics are considered one of the top pollutants that threaten the environment, aquatic life and mammalian (including human) health. Unfortunately, the development of uncomplicated but reliable analytical methods that are sensitive to individual microplastic particles, with sizes smaller than 1 μm, remains incomplete. Here, we demonstrate the detection and identification of (single) micro- and nanoplastics, by using surface-enhanced Raman spectroscopy (SERS), with Klarite substrates. Klarite is an exceptional SERS substrate; it is shaped as a dense grid of inverted pyramidal cavities, made of gold. Numerical simulations demonstrate that these cavities (or pits) strongly focus incident light into intense hotspots. We show that Klarite has the potential to facilitate the detection and identification of synthesized and atmospheric/aquatic microplastic (single) particles, with sizes down to 360 nm. We find enhancement factors of up to two orders of magnitude for polystyrene analytes. In addition, we detect and identify microplastics with sizes down to 450 nm on Klarite, with samples extracted from ambient, airborne particles. Moreover, we demonstrate Raman mapping as a fast detection technique for sub-micron microplastic particles. The results show that SERS with Klarite is a facile technique that has the potential to detect and systematically measure nanoplastics in the environment. This research is an important step towards detecting nanoscale plastic particles that may cause toxic effects to mammalian and aquatic life when present in high concentrations

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Pseudomyxoma Peritonei of Appendiceal Origin - 801 Cases from a Single Institution in China

Aim: As more and more centers has published their treatment results ofpseudomyxoma peritonei (PMP) with cytoreductive surgery (CRS) andhyperthermic intraperitoneal chemotherapy (HIPEC), the data from Chinais missing. Myxoma Department of Aerospace Hospital is the biggestcenter treating PMP in China. The purpose of this study is to report theearly and long-term outcomes for PMP from this single center. Methods:801 appendix-derived PMP out of 1008 consecutive patients treated inMyxoma Department of Aerospace Hospital between 2008 and 2019 wereretrospectively analyzed. Results: Complete cytoreductive surgery (CCRS)was achieved in 240 (30%) patients with median PCI of 14(1~39), andthe rest had maximal tumor debulking (MTD), HIPEC was implementedin 96.3% of CCRS and 78.6% of MTD. The major morbidity (gradeIII/IV) was 11.4% and the 30-day operative mortality is 0.7%. The 5-and 10-year OS of CCRS was 76.9% and 64.1%, which is significantlyhigher than MTD (5-, 10-year OS as 36.1%, 27.1%; p20, MTD, high pathologic grade and without HIPECwere independent factors predicting poorer prognosis. Conclusions: CCRS+HIPEC can benefit PMP well with controllable risks. MTD+HIPEC maybenefit PMP as well when CCRS cannot be achieved after fully asscessmentby an experienced peritoneal maglignacy center, but the surgery should beperformed as limited as possible

Pressure-induced emission of cesium lead halide perovskite nanocrystals.

Metal halide perovskites (MHPs) are of great interest for optoelectronics because of their high quantum efficiency in solar cells and light-emitting devices. However, exploring an effective strategy to further improve their optical activities remains a considerable challenge. Here, we report that nanocrystals (NCs) of the initially nonfluorescent zero-dimensional (0D) cesium lead halide perovskite Cs4PbBr6 exhibit a distinct emission under a high pressure of 3.01 GPa. Subsequently, the emission intensity of Cs4PbBr6 NCs experiences a significant increase upon further compression. Joint experimental and theoretical analyses indicate that such pressure-induced emission (PIE) may be ascribed to the enhanced optical activity and the increased binding energy of self-trapped excitons upon compression. This phenomenon is a result of the large distortion of [PbBr6]4- octahedral motifs resulting from a structural phase transition. Our findings demonstrate that high pressure can be a robust tool to boost the photoluminescence efficiency and provide insights into the relationship between the structure and optical properties of 0D MHPs under extreme conditions

Pressure-induced Large Emission Enhancements of Cadmium Selenide Nanocrystals.

Pressure-quenching of optical emission largely limits the potential application of many materials in optical pressure-sensing devices, since emission intensity is crucially connected to performance. Boosting visible-light emission at high pressure is, therefore, an important goal. Here, we demonstrate that the emission of CdSe nanocrystals (NCs) can be enhanced by more than an order of magnitude by compression. The brightest emission can be achieved at pressures corresponding to the phase transitions in different sized CdSe NCs. Very bright blue emission can be obtained by exploiting the increase in bandgap with increasing pressure. First-principles calculations indicate that the interaction between the capping oleic acid (OA) layer and the CdSe core is strengthened with increased Hirshfeld charge at high pressure. The effective surface reconstruction associated with the removal of surface-related trap states is highly responsible for the pressure-induced emission enhancement of these CdSe NCs. These findings pave the way for designing a stress nanogauge with easy optical readout and provide a route for tuning bright-fluorescence imaging in response to an externally-applied pressure.The authors acknowledge funding support from the National Key R&D Program of China (No. 2018YFA0305900), the National Natural Science Foundation of China (Nos. 21725304, 11774125, 61525404, 11504368, 11774120, 21673100, and 91227202), the Chang Jiang Scholars Program of China (No. T2016051), Changbai Mountain Scholars Program (No. 2013007), National Defense Science and Technology Key Laboratory Fund (6142A0306010917), Scientific Research Planning Project of the Education Department of Jilin Province (JJKH20180118KJ), and Program for Innovative Research Team (in Science and Technology) in University of Jilin Province. S.A.T.R. acknowledges the support of the NERC grant NE/P019714/1. X.F. is grateful for the support of the China Scholarship Council

CD180 Ligation Inhibits TLR7- and TLR9-Mediated Activation of Macrophages and Dendritic Cells Through the Lyn-SHP-1/2 Axis in Murine Lupus

Activation of TLR7 and TLR9 by endogenous RNA- or DNA-containing ligands, respectively, can lead to hyper-activation of immune cells, including macrophages and DCs, subsequently contributes to the pathogenesis of SLE. CD180, a TLR-like protein, is specifically involved in the development and activation of immune cells. Our previous study and others have reported that CD180-negative B cells are dramatically increased in SLE patients and responsible for the production of auto-antibodies. However, the mode of CD180 expression on macrophages and DCs in SLE remains unclear and the role of CD180 on regulating TLR7- and TLR9-mediated activation of macrophages and DCs are largely unknown. In the present study, we found that the percentages of CD180-negative macrophages and DCs were both increased in SLE patients and lupus-prone MRL/lpr mice compared with healthy donors and wild-type mice, respectively. Notably, ligation of CD180 significantly inhibited the activation of TLR7 and TLR9 signaling pathways in macrophages and DCs through the Lyn-SHP-1/2 axis. What's more, injection of anti-CD180 Ab could markedly ameliorate the lupus-symptoms of imiquimod-treated mice and lupus-prone MRL/lpr mice through inhibiting the activation of macrophages and DCs. Collectively, our results highlight a critical role of CD180 in regulating TLR7- and TLR9-mediated activation of macrophages and DCs, hinting that CD180 can be regarded as a potential therapeutic target for SLE treatment

Leukadherin-1-Mediated Activation of CD11b Inhibits LPS-Induced Pro-inflammatory Response in Macrophages and Protects Mice Against Endotoxic Shock by Blocking LPS-TLR4 Interaction

Dysregulation of macrophage has been demonstrated to contribute to aberrant immune responses and inflammatory diseases. CD11b, expressed on macrophages, plays a critical role in regulating pathogen recognition, phagocytosis, and cell survival. In the present study, we explored the effect of leukadherin-1 (LA1), an agonist of CD11b, on regulating LPS-induced pro-inflammatory response in macrophages and endotoxic shock. Intriguingly, we found that LA1 could significantly reduce mortalities of mice and alleviated pathological injury of liver and lung in endotoxic shock. In vivo studies showed that LA1-induced activation of CD11b significantly inhibited the LPS-induced pro-inflammatory response in macrophages of mice. Moreover, LA1-induced activation of CD11b significantly inhibited LPS/IFN-γ-induced pro-inflammatory response in macrophages by inhibiting MAPKs and NF-κB signaling pathways in vitro. Furthermore, the mice injected with LA1-treated BMDMs showed fewer pathological lesions than those injected with vehicle-treated BMDMs in endotoxic shock. In addition, we found that activation of TLR4 by LPS could endocytose CD11b and activation of CD11b by LA1 could endocytose TLR4 in vitro and in vivo, subsequently blocking the binding of LPS with TLR4. Based on these findings, we concluded that LA1-induced activation of CD11b negatively regulates LPS-induced pro-inflammatory response in macrophages and subsequently protects mice from endotoxin shock by partially blocking LPS-TLR4 interaction. Our study provides a new insight into the role of CD11b in the pathogenesis of inflammatory diseases