H₂‑Dependent Carbon Dissolution and Diffusion-Out in Graphene Chemical Vapor Deposition Growth

Highlighting the roles of H₂ on the carbon dissolution and diffusion-out unit steps in the metal substrate is highly imperative to constitute a whole puzzle elucidating how the H₂ affects the graphene chemical vapor deposition (CVD) growth, taking into account that the effects of H₂ on the surface process have been intensively emphasized. In this article, we designed a series of graphene growth experiments by introducing the H₂ in the individual unit step on the Cu and Co films as a comparison due to their distinctively intrinsic carbon solubility. We investigated the effects of H₂ on the crystallographic structure, surface morphology, and chemical environment of metal substrates, and the thickness and quality of as-grown graphene films. We also established the theoretical models to monitor the interaction between carbon and metal atoms with and without H₂. Our results demonstrate that the H₂ predissolution could suppress the carbon dissolution in the Cu film and enhance the diffusion-out of dissolved carbon atoms, whereas in the Co film the converse would occur

Electron impact ionization of water-doped superfluid helium nanodroplets: observation of He (H2O)+n clusters

Electron impact mass spectra have been recorded for helium nanodroplets containing water clusters. In addition to identification of both H+(H2O)n and (H2O)n+ ions in the gas phase, additional peaks are observed which are assigned to He(H2O)n+ clusters for up to n = 27. No clusters are detected with more than one helium atom attached. The interpretation of these findings is that quenching of (H2O)n+ by the surrounding helium can cool the cluster to the point where not only is fragmentation to H+(H2O)m (where m ⩽ n−1) avoided, but also, in some cases, a helium atom can remain attached to the cluster ion as it escapes into the gas phase. Ab initio calculations suggest that the first step after ionization is the rapid formation of distinct H3O+ and OH units within the (H2O)n+ cluster. To explain the formation and survival of He(H2O)n+ clusters through to detection, the H3O+ is assumed to be located at the surface of the cluster with a dangling O–H bond to which a single helium atom can attach via a charge-induced dipole interaction. This study suggests that, like H+(H2O)n ions, the preferential location for the positive charge in large (H2O)n+ clusters is on the surface rather than as a solvated ion in the interior of the cluster

Image_1_Survival prediction of hepatocellular carcinoma by measuring the extracellular volume fraction with single-phase contrast-enhanced dual-energy CT imaging.pdf

PurposeThis study aimed to investigate the value of quantified extracellular volume fraction (fECV) derived from dual-energy CT (DECT) for predicting the survival outcomes of patients with hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE).Materials and methodsA total of 63 patients with HCC who underwent DECT before treatment were retrospectively included. Virtual monochromatic images (VMI) (70 keV) and iodine density images (IDI) during the equilibrium phase (EP) were generated. The tumor VMI-fECV and IDI-fECV were measured and calculated on the whole tumor (Whole) and maximum enhancement of the tumor (Maximum), respectively. Univariate and multivariate Cox models were used to evaluate the effects of clinical and imaging predictors on overall survival (OS) and progression-free survival (PFS).ResultsThe correlation between tumor VMI-fECV and IDI-fECV was strong (both pConclusionThe quantified fECV determined by the equilibrium-phase contrast-enhanced DECT can potentially predict the survival outcomes of patients with HCC following TACE treatment.</p