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The melting at the magnesium/aluminum (Mg/Al) interface is an essential step during the fabrications of Mg-Al structural materials and biomaterials. We carried out molecular dynamics simulations on the melting at the Mg/Al interface in a Mg-Al-Mg nanolayer via analyzing the changes of average atomic potential energy, Lindemann index, heat capacity, atomic density distribution and radial distribution function with temperature. The melting temperatures (Tm) of the nanolayer and the slabs near the interface are significantly sensitive to the heating rate (vh) over the range ofvh ≤ 4.0 K ps-1. The distance (d) range in which the interface affects the melting of the slabs is predicted to be (-98.2, 89.9) Å atvhâ0,if the interface is put atd = 0 and Mg (Al) is located at the left (right) side of the interface. TheTmof the Mg (Al) slab just near the interface (e.g.d=4.0Å) is predicted to be 926.8 K (926.6 K) atvhâ0,with 36.9 K (37.1 K) below 963.7 K for the nanolayer. These results highlight the importance of regional research on the melting at an interface in the nanolayers consisting of two different metals.
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Thermal diffusion plays an important role in the determination of the structures and properties of interfaces and nanolayers. Here we report results from molecular dynamics simulations of the tensile behavior of Al-Mg-Al nanolayers with their Al/Mg interfaces being joined by the thermal diffusion of atoms. We find that a different deformation mechanism applies in each case: low thermal diffusion temperatures (300 ≤ T1 < 664 K) and high thermal diffusion temperatures (664 ≤ T1 ≤ 846 K). The formation of coherent Al/Mg interfaces in the case of high T1 induces the second hardening deformation of Al-Mg-Al nanolayers before the stress reaching the tensile strength, significantly enhancing the tensile properties of Al-Mg-Al nanolayers in comparison to the case of low T1. This difference would provide guidance on the improvement of the mechanical properties of Al-Mg layered systems.
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Molecular dynamics (MD) simulations are carried out to study the coalescence of identical adjacent and nonadjacent water films on graphene (G), vertically or horizontally stacked carbon nanotube arrays (VCNTA and HCNTA respectively). We highlight the key importance of carbon-based substrates in the growth of the liquid bridge connecting the two water films. This simulation provides reliable evidence to confirm a linear increase of the liquid bridge height, which is sensitive to the surface properties and the geometric structure. In the case of nonadjacent water films, the meniscus liquid bridge occurs solely on the VCNTA, which is attributed to the spreading of water films driven by the capillary force. Our results provide an available method to tune the coalescence of adjacent or nonadjacent films with alteration of topographically patterned surfaces, which has important implications in the design of condensation, ink-jet printing and drop manipulation on a substrate.
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The behavior of water droplets located on graphene in the presence of various external electric fields (E-fields) is investigated using classical molecular dynamics (MD) simulations. We explore the effect of E-field on mass density distribution, water polarization as well as hydrogen bonds (H-bonds) to gain insight into the wetting properties of water droplets on graphene and their interfacial structure under uniform E-fields. The MD simulation results reveal that the equilibrium water droplets present a hemispherical, a conical and an ordered cylindrical shape with the increase of external E-field intensity. Accompanied by the shape variation of water droplets, the dipole orientation of water molecules experiences a remarkable change from a disordered state to an ordered state because of the polarization of water molecules induced by static E-field. The distinct two peaks in mass density and H-bond distribution profiles demonstrate that water has a layering structure in the interfacial region, which sensitively depends on the strong E-field (>0.8 V nm(-1)). In addition, when the external E-field is parallel to the substrate, the E-field would make the contact angle of the water droplets become small and increase its wettability. Our findings provide the possibility to control the structure and wetting properties of water on graphene by tuning the direction and intensity of external E-field which is of importance for relevant industrial processes on the solid surface.
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This paper uses green innovation and environmental pollution as the mediating variables to construct a mediating effect model to investigate whether China's carbon emission trading policy can improve regional eco-efficiency by reducing regional environmental pollution and stimulating green innovation. This study is based on panel data from 30 provinces and municipalities directly under China's central government and autonomous regions from 2003 to 2019. The eco-efficiency of these provinces is measured using the super-efficiency DEA model and the difference-in-difference method (DID). The results show that (1) China's emission trading policy significantly improves regional ecological efficiency and the per capita GDP. The improvement can effectively improve regional ecological efficiency. (2) The mediating effect of green innovation and environmental pollution is significant. That is, China's carbon emission trading policy further improves regional ecological efficiency by stimulating more green innovation and reducing the synergy brought by environmental pollution. (3) There are differences in the feedback of this impact mechanism between different regions: It shows the characteristics of the western region being more significant than the eastern region. The central region has no significant effect. The research conclusion can provide a policy reference for the subsequent unified promotion of the construction of a carbon emission trading market nationwide and a theoretical basis for helping to achieve the "dual carbon" goal.
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Carbono , Contaminación Ambiental , China , Política AmbientalRESUMEN
Background: In recent years, we have observed the pivotal role of immunotherapy in improving survival for patients with non-small cell lung cancer (NSCLC). However, the effectiveness of immunotherapy in the perioperative (neoadjuvant + adjuvant) treatment of resectable NSCLC remains uncertain. We conducted a comprehensive analysis of its antitumor efficacy and adverse effects (AEs) by pooling data from the KEYNOTE-671, NADIM II, and AEGEAN clinical trials. Methods: For eligible studies, we searched seven databases. The randomized controlled trials (RCTs) pertaining to the comparative analysis of combination neoadjuvant platinum-based chemotherapy plus perioperative immunotherapy (PIO) versus perioperative placebo (PP) were included. Primary endpoints were overall survival (OS) and event-free survival (EFS). Secondary endpoints encompassed drug responses, AEs, and surgical outcomes. Results: Three RCTs (KEYNOTE-671, NADIM II, and AEGEAN) were included in the final analysis. PIO group (neoadjuvant platinum-based chemotherapy plus perioperative immunotherapy) exhibited superior efficacy in OS (hazard ratio [HR]: 0.63 [0.49-0.81]), EFS (HR: 0.61 [0.52, 0.72]), objective response rate (risk ratio [RR]: 2.21 [1.91, 2.54]), pathological complete response (RR: 4.36 [3.04, 6.25]), major pathological response (RR: 2.79 [2.25, 3.46]), R0 resection rate (RR: 1.13 [1.00, 1.26]) and rate of adjuvant treatment (RR: 1.08 [1.01, 1.15]) compared with PP group (neoadjuvant platinum-based chemotherapy plus perioperative placebo). In the subgroup analysis, EFS tended to favor the PIO group in almost all subgroups. BMI (>25), T stage (IV), N stage (N1-N2) and pathological response (with pathological complete response) were favorable factors in the PIO group. In the safety assessment, the PIO group exhibited higher rates of serious AEs (28.96% vs. 23.51%) and AEs leading to treatment discontinuation (12.84% vs. 5.81%). Meanwhile, although total adverse events, grade 3-5 adverse events, and fatal adverse events tended to favor the PP group, the differences were not statistically significant. Conclusion: PIO appears to be superior to PP for resectable stage II-III NSCLC, demonstrating enhanced survival and pathological responses. However, its elevated adverse event (AE) rate warrants careful consideration. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier CRD42023487475.
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Recent millimetre-scale studies proposed that ultrasonic vibrations (UVs) promote material flow in welding joints via acting on dislocations. Here, we report atomic-scale results from molecular dynamics simulations of Mg-Al nanolayers joined by two means: only heat and heat accompanied by UVs (vibration amplitude, B = 0.1-10 nm and vibration frequency, f = 5.7-100 GHz) over the temperature range of 600-800 K. Comparative and quantitative analyses were performed on the structural evolution (including atomic diffusion, arrangements and distributions) of the joining Mg/Al interfaces and motions of dislocations, as well as on the influences of the vibration amplitude and vibration frequency on these two features. The results show that the applied UV with large vibration amplitudes (B ≥ 5 nm) and a low vibration frequency (f = 5.7 GHz) significantly facilitates atomic diffusion (10-1000 times as fast as that in the case free of UVs) and formations and motions of dislocations, resulting in nonuniform-to-uniform structural transitions and increases in the thicknesses of the joined Mg/Al interfaces. These results provide a way to understand how the applied UV acts on dislocations and atomic diffusion during the UV-assisted welding processes of Mg-Al and other systems.
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Extracellular vesicles (EVs) can intercellularly transmit a wide range of bioactive molecules, and these cargoes may potentially serve as therapeutic biomarkers for preeclampsia. Herein, the current study aims to elucidate the mechanism underlying the human trophoblast cell-derived EV-mediated miRNA-mRNA network that could potentially influence the development of preeclampsia based on microarray datasets from publicly available GEO databases. Preeclampsia-related genes were retrieved from the GeneCards and CTD databases, which were then subjected to GO and KEGG enrichment analyses in an effort to identify key pathways in preeclampsia. The obtained results suggested an important role of the immune- and inflammation-related pathways in preeclampsia. Infiltration proportion of 22 immune cells was subsequently analyzed using the CIBERSORT algorithm. Placental tissues of patients with preeclampsia presented with increased proportion of resting NK cells and resting dendritic cells, while there was a reduction in the proportion of activated NK cells. Differentially expressed mRNAs were additionally predicted in the preeclampsia-related datasets retrieved from the GEO database, and then intersected with preeclampsia-related genes to identify the key genes. HLA-G was indicated as a key target gene in the development of preeclampsia and further associated with hypoxia, immune, and inflammatory pathways. The upstream microRNAs (miRNAs/miRs) of the key genes were further predicted and intersected with differentially expressed miRNAs in the human trophoblast cell-derived EV-related datasets from the GEO database to obtain the key miRNAs. EVs secreted by human trophoblast cells under hypoxic conditions were associated with 3 key upstream miRNAs of HLA-G, namely miR-1273d, miR-4492, and miR-4417, which might be implicated in the development of preeclampsia via targeting of HLA-G. Collectively, our findings highlighted that EVs secreted by human trophoblast cells under hypoxic conditions transferred miR-1273d, miR-4492, and miR-4417, all of which targeted HLA-G, thus orchestrating immune- and inflammation-related pathways and consequently promoting the development of preeclampsia.
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Vesículas Extracelulares , MicroARNs , Preeclampsia , Vesículas Extracelulares/metabolismo , Femenino , Antígenos HLA-G/genética , Antígenos HLA-G/metabolismo , Humanos , Inflamación/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Placenta/metabolismo , Preeclampsia/genética , Preeclampsia/metabolismo , Embarazo , ARN Mensajero/metabolismo , Trofoblastos/metabolismoRESUMEN
OBJECTIVE: To identify the resources of Gynostemma pentaphyllum and its spurious breed plant Cayratia japonica at level of DNA. METHODS: Two random primers ( WGS001, WGS004) screened were applied to do random amplification with genomic DNA extracted from Gynostemma pentaphyllum and Cayratia japonica which were collected from different habitats. After amplificated with WGS004, one characteristic fragment about 500 bp which was common to all Gynostemma pentaphyllum samples studied but not to Cayratia japonica was cloned and sequenced. Then these sequences obtained were analyzed for identity and compared by Blastn program in GenBank. RESULTS: There were obvious different bands amplified by above two primers in their fingerprints of genomic DNA. On the basis of these different bands of DNA fingerprints, they could distinguish Gynostemma pentaphyllum and Cayratia japonica obviously. Sequence alignment of seven cloned bands showed that their identities ranged from 45.7% - 94.5%. There was no similar genome sequences searched in GenBank. This indicated that these seven DNA fragments had not been reported before and they should be new sequences. CONCLUSION: RAPD technique can be used for the accurate identification of Gynostemma pentaphyllum and its counterfeit goods Cayratia japonica. Besides, these specific DNA sequences for Gynostemmna pentaphyllum in this study are useful for the further research on identification of species and assisted selection breeding in Gynostemma pentaphyllum.
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ADN de Plantas/genética , Gynostemma/genética , Plantas Medicinales/genética , Técnica del ADN Polimorfo Amplificado Aleatorio , Vitaceae/genética , Clonación Molecular , Cartilla de ADN , Contaminación de Medicamentos , Marcadores Genéticos , Gynostemma/clasificación , Análisis de Secuencia de ADN , Vitaceae/clasificaciónRESUMEN
OBJECTIVE: To analyze the DNA molecular characters of Centella asiatica with RAPD technology. METHODS: With the genomic DNA as templates extracted from various source of Centella asiatica samples, optimized RAPD PCR reaction systems had been used. The random promers had been screened to amplify the specific molecular fragments of Centella asiatica. RESULTS: The specific genetic bands of Centella asiatica species from various habitats were established which were highly stable and repeatable and obviously different from those of other families, genuses of plants such as Gynostemma pentaphylum, Tobacco, Cayratia japonica. CONCLUSION: The developed method of RAPD analysis for the genetic character bands of Centella asiatica could be applied to identify real Centella asiatica from its spurious breed plants. The genetic character bands of Centella asiatica amplified with the RAPD method show high homogeneous in several samples from different habitats.
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Centella/genética , ADN de Plantas/genética , Plantas Medicinales/genética , Técnica del ADN Polimorfo Amplificado Aleatorio/métodos , Centella/clasificación , Cartilla de ADN , ADN de Plantas/aislamiento & purificación , Contaminación de Medicamentos , Marcadores Genéticos , Genoma de Planta , Gynostemma/clasificación , Gynostemma/genética , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADNRESUMEN
Controlling droplet dynamics via wettability or movement at the nanoscale is a significant goal of nanotechnology. By performing molecular dynamics simulations, we study the wettability and spontaneous coalescence of Cu droplets confined in two carbon walls. We first focus on one drop in the two-wall confinement to reveal confinement effects on wettability and detaching behavior of metallic droplets. Results show that Cu droplets finally display three states: non-detachment, semi-detachment and full detachment, depending on the height of confined space. The contact angle ranges from 125° to 177°, and the contact area radius ranges from 12 to ~80 Å. The moving time of the detached droplet in the full detachment state shows a linear relationship with the height of confined space. Further investigations into two drops subjected to confinement show that the droplets, initially distant from each other, spontaneously coalesce into a larger droplet by detachment. The coalescing time and final position of the merged droplet are precisely controlled by tailoring surface structures of the carbon walls, the height of the confined space or a combination of these approaches. These findings could provide an effective method to control the droplet dynamics by confinement.
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The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties.
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The structure of quasi-2D liquid silicon confined to slit nanopores has been investigated using molecular dynamics (MD) simulations. An obvious structural change from a low-density low-coordinated liquid to a high-density highly coordinated liquid has been found in the confined silicon with the increase of the slit size. This kind of structural transition results from layering in the confined silicon, which disappears with the increase of temperature. In the process of layering transition, the coordination distribution of quasi-2D liquid undergoes an evolutionary process from the initial non-uniform distribution to the final uniform distribution. In addition, our results also indicate that the increase of pressure will also induce a layering transition in the confined silicon.
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Nanoporos , Silicio/química , PresiónRESUMEN
In this work, we report simulation evidence that the graphene surface decorated by carbon nanotube pillars shows strong dewettability, which can give it great advantages in dewetting and detaching metallic nanodroplets on the surfaces. Molecular dynamics (MD) simulations show that the ultrathin liquid film first contracts then detaches from the graphene on a time scale of several nanoseconds, as a result of the inertial effect. The detaching velocity is in the order of 10â m/s for the droplet with radii smaller than 50â nm. Moreover, the contracting and detaching behaviors of the liquid film can be effectively controlled by tuning the geometric parameters of the liquid film or pillar. In addition, the temperature effects on the dewetting and detaching of the metallic liquid film are also discussed. Our results show that one can exploit and effectively control the dewetting properties of metallic nanodroplets by decorating the surfaces with nanotube pillars.
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Molecular dynamics simulations are performed to study the cooling process of quasi-2D liquid carbon. Our results show an obvious liquid-liquid phase transition (LLPT) from the twofold coordinated liquid to the threefold coordinated liquid with the decrease of temperature, followed by a liquid-solid phase transition (LSPT). The LLPT can be regarded as the preparation stage of LSPT. During the cooling process, the chain structures firstly self-assemble into some ring structures and then aggregate into some stable islands which can further connect together to form a complete polycrystalline film. The threefold coordinated structures play an important role in the formation of atomic rings. The inheritance of the threefold coordinated structures provides essential condition to form rings and islands.