No abstract

Nanometer-thick passive films on metals usually impart remarkable resistance to general corrosion but are susceptible to localized attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, several classic theories have been proposed and accepted, based on hypotheses and theoretical models, and oftentimes, not sufficiently nor directly corroborated by experimental evidence. Here we show experimental results on the structure of the passive film formed on a FeCr15Ni15 single crystal in chloride-free and chloride-containing media. We use aberration-corrected transmission electron microscopy to directly capture the chloride ion accumulation at the metal/film interface, lattice expansion on the metal side, undulations at the interface, and structural inhomogeneity on the film side, most of which had previously been rejected by existing models. This work unmasks, at the atomic scale, the mechanism of chloride-induced passivity breakdown that is known to occur in various metallic materials.

Reciprocal relationship usually exists between osteoblastogenesis and adipogenesis, with factors stimulating one of these processes at the same time inhibiting the other. In the present study, miR-30e was found to be involved in the reciprocal regulation of osteoblast and adipocyte differentiation. Our data indicated that miR-30e was induced in primarily cultured mouse bone marrow stromal cell, mesenchymal cell line C3H10T1/2 and preadipocyte 3T3-L1 after adipogenic treatment. Conversely, it was reduced in mouse stromal line ST2 and preosteoblast MC3T3-E1 after osteogenic treatment. Enforced expression of miR-30e in 3T3-L1 significantly suppressed the growth of the cells and induced the preadipocytes to differentiate into mature adipocytes, along with increased expression of adipocyte-specific transcription factors peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT/enhancer binding protein-α (C/EBPα) and C/EBPβ, and the marker gene aP2. In contrast, inhibition of the endogenous miR-30e enhanced the cell growth and repressed preadipocytes to differentiate. Conversely, supplementing miR-30e activity blocked, whereas knocking down miR-30e enforced the preosteoblast MC3T3-E1 to fully differentiate. Furthermore, miR-30e overexpression stimulated adipocyte formation and inhibited osteoblast differentiation from marrow stromal cells. Low-density lipoprotein receptor-related protein 6 (LRP6), one of the critical coreceptor for Wnts, was shown to be a direct target of miR-30e by using the luciferase assay. Knockdown of LRP6 in 3T3-L1 cells downregulated β-catenin/T-cell factor (TCF) transcriptional activity and dramatically potentiated the differentiation of the cells into mature adipocytes. Taken together, the present work suggests that the expression of miR-30e is indispensable for maintaining the balance of adipocytes and osteoblasts by targeting the canonical Wnt/β-catenin signaling.

We present the X-ray timing results of the new black hole candidate (BHC) MAXI J1535-571 during its 2017 outburst from Hard X-ray Modulation Telescope (Insight -HXMT) observations taken from 2017 September 6 to 23. Following the definitions given by Belloni (2010), we find that the source exhibits state transitions from Low/Hard state (LHS) to Hard Intermediate state (HIMS) and eventually to Soft Intermediate state (SIMS). Quasi-periodic oscillations (QPOs) are found in the intermediate states, which suggest different types of QPOs. With the large effective area of Insight -HXMT at high energies, we are able to present the energy dependence of the QPO amplitude and centroid frequency up to 100 keV which is rarely explored by previous satellites. We also find that the phase lag at the type-C QPOs centroid frequency is negative (soft lags) and strongly correlated with the centroid frequency. By assuming a geometrical origin of type-C QPOs, the source is consistent with being a high inclination system.

The morphologies of iPP fiber/matrix homogeneity composites were studied on a lamellar level with the help of a field emission scanning electron microscope. It is found that the induced supermolecular structure of iPP depends strongly upon the fiber introduction temperature. At temperatures lower than 164 °C, no melting of the original iPP fiber takes place, and the solid iPP fiber can initiate only the growth of parallel aligned R-iPP lamellae normal to the fiber axis. At temperatures above 165 °C, the morphological change from the microfibrils to lamellae implies the occurrence of melting and recrystallization of the iPP fiber during sample preparation. At the same time, the increment of β-iPP content with the increase of fiber introduction temperature demonstrates unambiguously that the β-iPP crystallization is associated with the above-mentioned melting and recrystallization process. Combining the structural features of the recrystallized iPP fibers and the induced interfacial layers, it is suggested that the chain orientation status in the molten iPP fiber plays an important role in subsequent β-iPP crystallization.

We revealed the gene mutation spectrum in Chinese OI patients, and novel mutations identified here expanded the mutation catalog and genotype and phenotype relationships among OI patients.

Objective: To explore the value of postoperative transarterial chemoembolization (TACE) and portal vein chemotherapy (PVC) in patients with hepatocellular carcinoma (HCC) in the prevention of recurrence, and to evaluate prognostic factors in a randomized study. Method: 131 patients with HCC were randomly divided into 3 groups: operation only (group A, n = 45); operation plus TACE (group B, n = 39), and operation plus TACE and PVC (group C, n = 47). Disease-free survival rates as well as prognostic factors were analyzed. Results: Most of the side effects and complications related to the operation, catheters and local chemotherapy were liver decompensation (16.1%), catheter obstruction (12.9%), and nausea and loss of appetite (25.8%), respectively. The disease-free survival curves were significantly different between the 3 groups as estimated by the Kaplan-Meier method (p < 0.05). Group C had a significantly higher disease-free survival rate compared to group A (p < 0.05). But no statistical differences were found between groups A and B and groups B and C (both p > 0.05). Tumor number and treatment modalities were independent prognostic factors for HCC patients (p < 0.05). Conclusion: Postoperative TACE combined with PVC may benefit the survival of patients with HCC. In specialized medical centers, aggressive methods such as TACE and PVC should be attempted on HCC patients without contraindications.

We study the evolution of the temporal properties of MAXIJ1820+070 during the 2018 outburst in its hard state from MJD58,190 to 58,289 with Insight-HXMT in a broad energy band 1-150 keV. We find different behaviors of the hardness ratio, the fractional rms and time lag before and after MJD58,257, suggesting a transition occurred around this point. The observed time lags between the soft photons in the 1-5 keV band and the hard photons in higher energy bands, up to 150 keV, are frequency-dependent: the time lags in the low-frequency range, 2-10mHz, are both soft and hard lags with a timescale of dozens of seconds but without a clear trend along the outburst; the time lags in the high-frequency range, 1-10Hz, are only hard lags with a timescale of tens of milliseconds; they first increase until around MJD58,257 and decrease after this date. The high-frequency time lags are significantly correlated to the photon index derived from the fit to the quasi-simultaneous NICER spectrum in the 1-10 keV band. This result is qualitatively consistent with a model in which the high-frequency time lags are produced by Comptonization in a jet.Unified Astronomy Thesaurus concepts: Black holes (162); Compact objects (288); Low-mass x-ray binary stars (939)