Abstract Background Gastric cancer is one of most common malignancies in the world. Currently the prognostic prediction is entirely based on the TNM staging system. In this study, we evaluated ...whether metastatic lymph node ratio (rN) at the time of surgery would improve the prognostic prediction in conjunction with the TNM staging system. Methods This retrospective study includes 745 patients, who had been referred for surgery due to gastric cancer between 1995 and 2007 and had at least 15 lymph nodes examined at the time of surgery without preoperative treatment. Clinicopathologic features and overall survival were analyzed using univariate and multivariate modes to identify the risk factors for overall survival. Results Median overall survival of all patients analyzed is 57.8 months and 5-year overall survival is 49.5%. Tumor site, macroscopic type, pTNM stage, and rN stage are identified as independent prognostic factors. Increased positive lymph node ratio correlates with shorter survival in all patients and in each T and N stage. In stage III gastric cancer patients, rN stage shows additional prognostic value on overall survival ( p < 0.001). Conclusions rN stage is a simple and promising prognostic factor of gastric cancer after surgery in addition to the TNM stage system especially in stage III patients. But the independent prognostic value of rN stage in stage I, II and IV gastric cancer is yet to be determined.
Magnetic particle imaging is an emerging tomographic technique with the potential for simultaneous high-resolution, high-sensitivity, and real-time imaging. Magnetic particle imaging is based on the ...unique behavior of superparamagnetic iron oxide nanoparticles modeled by the Langevin theory, with the ability to track and quantify nanoparticle concentrations without tissue background noise. It is a promising new imaging technique for multiple applications, including vascular and perfusion imaging, oncology imaging, cell tracking, inflammation imaging, and trauma imaging. In particular, many neuroimaging applications may be enabled and enhanced with magnetic particle imaging. In this review, we will provide an overview of magnetic particle imaging principles and implementation, current applications, promising neuroimaging applications, and practical considerations.
Energetic electron depletions are a notable feature of the nightside Martian upper atmosphere. In this study, we investigate systematically the variations of the occurrence of depletions with both ...internal and external conditions, using the extensive Solar Wind Electron Analyzer measurements made on board the Mars Atmosphere and Volatile Evolution. In addition to the known trends of increasing occurrence with decreasing altitude and increasing magnetic field intensity, our analysis reveals that depletions are more easily observed in regions with near horizontal magnetic fields and under low solar wind (SW) dynamic pressures. We also find that below 160 km, the occurrence increases with increasing CO2 density, a trend mostly visible in weakly magnetized regions. These observations have important implications on the formation of electron depletions: (1) Near strong magnetic anomalies, closed magnetic loops preferentially form and shield the atmosphere from direct access of SW electrons, a process that is modulated by the upstream SW condition; and (2) in weakly magnetized regions, SW electrons precipitate into the atmosphere unhindered, but at sufficiently low altitudes, they are either “absorbed” due to inelastic collisions with ambient neutrals or shielded again in response to a change in magnetic connectivity from open to closed. Our analysis further reveals that both the ionospheric plasma content and thermal electron temperature are reduced in regions with depletions compared to regions without, supporting SW electron precipitation as an important source of external energy driving the variability in the deep nightside Martian upper atmosphere and ionosphere.
Key Points
Electron depletions in the nightside Martian ionosphere are more easily observed in regions with near horizontal magnetic fields
Electron depletions are more easily observed under low solar wind dynamic pressures
Substantially reduced ionospheric plasma content and thermal electron temperature are observed in regions with depletions
Chemically modified graphene and polyaniline (PANI) nanofiber composites were prepared by in situ polymerization of aniline monomer in the presence of graphene oxide under acid conditions. The ...obtained graphene oxide/PANI composites with different mass ratios were reduced to graphene using hydrazine followed by reoxidation and reprotonation of the reduced PANI to give the graphene/PANI nanocomposites. The morphology, composition, and electronic structure of the composites together with pure polyaniline fibers (PANI-F), graphene oxide (GO), and graphene (GR) were characterized using X-ray diffraction (XRD), solid-state 13C NMR, FT-IR, scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). It was found that the chemically modified graphene and the PANI nanofibers formed a uniform nanocomposite with the PANI fibers absorbed on the graphene surface and/or filled between the graphene sheets. Such uniform structure together with the observed high conductivities afforded high specific capacitance and good cycling stability during the charge−discharge process when used as supercapacitor electrodes. A specific capacitance of as high as 480 F/g at a current density of 0.1 A/g was achieved over a PANI-doped graphene composite. The research data revealed that high specific capacitance and good cycling stability can be achieved either by doping chemically modified graphenes with PANI or by doping the bulky PANIs with graphene/graphene oxide.
Context.
Characterizing the response of the upper Martian atmosphere to solar flares could provide important clues as to the climate evolution of the red planet in the early Solar System, when the ...extreme ultraviolet and soft X-ray radiation was substantially higher than the present-day level and when these events occurred more frequently. A critical process herein is the Martian atmospheric escape in the form of atomic C and N, as mainly driven by CO
2
/CO and N
2
dissociation.
Aims.
This study is devoted to evaluating how these escape rates varied on the dayside of Mars during the X8.2 solar flare on 10 September 2017.
Methods.
The background Martian atmospheric structures, before, during, and after the flare, are constructed from the Neutral Gas and Ion Mass Spectrometer measurements made on board the Mars Atmosphere and Volatile Evolution spacecraft, from which the hot C and N production rate profiles via different photon and photoelectron impact channels and on different flare stages are obtained. They are combined with the respective escape probability profiles computed using a test particle Monte Carlo approach to derive the atomic C and N escape rates on the dayside of Mars.
Results.
Our calculations indicate that the pre-flare C and N escape rates are (1.3−1.4) × 10
24
s
−1
over the dayside of Mars. During the event, we find a modest decrease in the C escape rate of 8% about 1 h after the flare peak, followed by a recovery to the pre-flare level several hours later. However, an opposite trend is found for the N escape rate during the same period, which shows an increase of 20% followed by a recovery to the pre-flare level.
Conclusions.
The distinction between C and N in terms of the variation in the escape rate during the solar flare reflects the competition between two flare-induced effects: enhanced hot atom production via dissociation and enhanced collisional hindrance due to atmospheric expansion.
Recent development in proton-exchange membrane fuel cell technology has stimulated research in fuel processing for hydrogen production. Hydrogen can be produced from four different types of methanol ...reforming processes, namely methanol decomposition, partial oxidation of methanol, steam reforming of methanol and oxidative steam reforming of methanol. This review paper discusses commonly used Cu-based catalysts including their kinetic, compositional, and morphological characteristics in methanol reforming reactions. Although research exploring surface reaction mechanism over various Cu-based catalysts was first attempted about three decades ago, the scheme remains controversial. This technical discussion will focus on the commonly reported surface intermediate species, which are methoxy, formaldehyde, dioxymethylene, formate and methyl formate. The surface reaction mechanism could be complicated by the introduction of reactants such as oxygen and steam, into the system as they would subsequently initiate secondary reactions. Different reaction schemes of methanol reforming are presented.
•All four systems of methanol reforming to produce hydrogen were considered.•Cu-based catalysts, Cu sintering and modifications were discussed.•Surface reaction mechanisms involving common intermediate species were outlined.•Reaction schemes were complicated by secondary reactions.
We previously demonstrated that fermitin family member 1 (FERMT1) was significantly overexpressed in colon cancer (CC) and associated with poor metastasis-free survival. This study aimed to ...investigate the precise role of FERMT1 in CC metastasis and the mechanism by which FERMT1 is involved in the epithelial-mesenchymal transition (EMT). Correlations between FERMT1 and EMT markers (E-cadherin, Slug, N-cadherin and β-catenin) were examined via immunohistochemistry in a cohort of CC tissues and adjacent normal colon mucosae. A series of in vitro and in vivo assays were performed to elucidate the function of FERMT1 in CC metastasis and underlying mechanisms. The upregulated expression of FERMT1 in CC tissues correlated positively with that of Slug, N-cadherin and β-catenin, but correlated inversely with E-cadherin expression. Altered FERMT1 expression led to marked changes in the proliferation, migration, invasion and EMT markers of CC cells both in vitro and in vivo. Investigations of underlying mechanisms found that FERMT1 interacted directly with β-catenin and activated the Wnt/β-catenin signaling pathway by decreasing the phosphorylation level of β-catenin, enhancing β-catenin nuclear translocation and increasing the transcriptional activity of β-catenin/TCF/LEF. Activation of the Wnt/β-catenin pathway by CHIR99021 reversed the effect of FERMT1 knockdown, whereas inhibition of the Wnt/β-catenin pathway by XAV939 impaired the effect of FERMT1 overexpression on EMT and cell motility. In conclusion, findings of this study suggest that FERMT1 activates the β-catenin transcriptional activity to promote EMT in CC metastasis.
Two-dimensional (2D) materials have been studied extensively as monolayers, vertical or lateral heterostructures. To achieve functionalization, monolayers are often patterned using soft lithography ...and selectively decorated with molecules. Here we demonstrate the growth of a family of 2D materials that are intrinsically patterned. We demonstrate that a monolayer of PtSe
can be grown on a Pt substrate in the form of a triangular pattern of alternating 1T and 1H phases. Moreover, we show that, in a monolayer of CuSe grown on a Cu substrate, strain relaxation leads to periodic patterns of triangular nanopores with uniform size. Adsorption of different species at preferred pattern sites is also achieved, demonstrating that these materials can serve as templates for selective self-assembly of molecules or nanoclusters, as well as for the functionalization of the same substrate with two different species.
Global dust storms (GDS) are an important dynamical phenomenon of the Martian lower atmosphere but are known to have important impacts on the Martian middle/upper atmosphere and ionosphere. Despite ...extensive studies over the past several decades, how the composition of the Martian ionosphere is modified during the GDS has only been studied from a theoretical point of view. Here we present for the first time the observations of the compositional variation of the Martian ionosphere during the GDS in 2018, using the ion density measurements made by the Neutral Gas and Ion Mass Spectrometer onboard the Mars Atmosphere and Volatile Evolution. At a representative altitude of 170 km, the variations of ionospheric species during the GDS show either enhancement (CO2+, Ar+, HO2+, H2O+, H2+, ArH+) or depletion (O2+, O+, N2+/CO+, OH+). Despite the apparent diversity, the observations are mostly understandable within the established framework of ionospheric chemistry on Mars, which further demonstrates that the variation of ion species during the GDS is a good diagnostic of the variation of relevant neutral species in the thermosphere. In particular, the observed ionospheric variation strongly supports a scenario that H2O is substantially enhanced in the Martian thermosphere during the GDS. However, the variations of O2+ and H2+ are inconsistent with predictions from ionospheric chemistry and require further investigation.
Plain Language Summary
Global dust storms (GDS) are an important dynamical phenomenon of the Martian climate that has been extensively studied over the past several decades. Though occurring in the lower atmosphere, they are known to have important impacts on the upper atmosphere and ionosphere, such as increasing the thermospheric water content, enhancing hydrogen escape, and lifting the ionospheric layer. Despite the existing efforts, how the composition of the Martian ionosphere is modified by has not been well studied. Owing to the accumulation of the ion density measurements made onboard the Mars Atmosphere and Volatile Evolution and the dust opacity measurements made onboard the Mars Reconnaissance Orbiter, we present for the first time a preliminary investigation of the species‐dependent variations of the dayside Martian ionosphere during the GDS in 2018. The responses of various ionospheric species to this event show diverse features, some demonstrating clear enhancement, whereas the others demonstrating clear depletion. Despite this, the observations are mostly consistent with the established ionospheric chemistry on Mars, implying that the variation of ionospheric species during a GDS is closely linked to the variation of neutral species in the thermosphere during the same event.
Key Points
Variations of the Martian ionosphere during global dust storms are species dependent, displaying either density enhancement or depletion
The variations of most ion species except for O2+ and H2+ are interpreted using the ionospheric chemistry on Mars
Substantial enhancement in thermospheric H2O on Mars during global dust storms are implied by ion measurements
The neutral heating efficiency is commonly defined as the fraction of the solar extreme ultraviolet and X-ray energy absorbed by a planetary atmosphere that ends up as local heat. It is a crucial ...parameter that determines the upper atmospheric temperature and, consequently, the thermal escape rate on both solar system bodies and exoplanets. Combining the Mars Atmosphere and Volatile Evolution measurements of a variety of atmospheric parameters, we calculate the neutral heating efficiency in the dayside Martian upper atmosphere based on a complicated network of microscopic processes, including photon and photoelectron impact processes, as well as exothermic chemical reactions. Our calculations indicate that neutral heating is mainly contributed by photon impact at low altitudes, of which the bulk occurs via CO2 photodissociation, and exothermic chemistry at high altitudes, of which the bulk occurs via and dissociative recombination. Collisional quenching of metastable neutrals and ions, which is of great interest in the literature, contributes to local heating by no more than 10% at all altitudes. In the dayside median sense, the neutral heating efficiency remains roughly constant at 20% from 150 to 200 km and increases steadily to 32% near 250 km. The heating efficiency at 150-200 km shows a weak correlation with solar zenith angle, increases modestly with increasing solar activity, and is clearly enhanced over strong crustal magnetic anomalies. Throughout the study, strict local heating is assumed, but nonlocal heating does not affect our results near or below 200 km.
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