Atomic structure and structural stability of Fe90Sc10 nanoglasses

Nanoglasses are non-crystalline solids whose internal structure is characterized by fluctuations of the free volume. Due to the typical dimensions of the structural features in the nanometer-range and the disordered atomic structure of the interfacial regions, the atomic structure and the structural stability of nanoglasses is not yet completely understood. Nanoglasses are typically produced by consolidation of glassy nanoparticles. Consequently, the basis for the understanding of the atomic structure of nanoglasses lies in the atomic structure of the primary glassy nanoparticles. Using electron energy loss spectroscopy, the elemental distribution in the Fe90Sc10 primary glassy nanoparticles and in the corresponding nanoglasses produced by consolidation of these glassy nanoparticles have been studied. Due to surface segregation, Fe has been found to be enriched at the surface of the primary Fe90Sc10 glassy nanoparticles. This behavior was found to be consistent with theoretical results based on a monolayer model for surface segregation behavior of the binary liquid alloys. In addition, the heterogeneous structure of Fe90Sc10 nanoglasses with Fe enriched interfaces was also directly observed, and may be attributed to the segregation of the primary glassy nanoparticles on the surface. Furthermore, the electron density of the isolated and loosely compacted primary glassy nanoparticles was investigated using small- and wide- angle X-ray scattering. The results indicate that the surface shells of glassy nanoparticles have an electron density that is lower than the electron density in the cores of the glassy nanoparticles. The lower electron density seems to result mainly from a lower atomic packing density of the surface shells rather than from compositional variations due to the surface segregation. During the consolidation of the glassy nanoparticles, the inhomogeneous elemental distribution and the short-range order in the shells of Fe90Sc10 glassy nanoparticles can be transferred into the interfaces of the resulting bulk Fe90Sc10 nanoglasses. The free volume within the shells of the Fe90Sc10 glassy nanoparticles may delocalize into the interfaces between the Fe90Sc10 glassy nanoparticles resulting in interfacial regions of lower atomic packing density in the Fe90Sc10 nanoglasses. The structural stability of Fe90Sc10 nanoglasses has been studied by means of low temperature annealing in situ in a transmission electron microscope, and ex situ in an ultra-high-vacuum tube-furnace. The analysis of both experiments showed similar results. The structure of the Fe90Sc10 nanoglasses was stable for up to 2 hours when annealed at 150 °C. Annealing of nanoglasses at higher temperatures resulted in the formation of a metastable nanocrystalline bcc-Fe(Sc) with Sc-enriched interfaces. The crystallization process of Fe90Sc10 nanoglasses was clarified and a plausible mechanism for the structural stability was proposed

Evaluation of tobacco use on Chinese population through ATTOC model: a cross-sectional survey on hospitalized psychiatric patients

OBJECTIVES: To evaluate the feasibility of Addressing Tobaccos through Organizational Change (ATTOC) intervention to Chinese psychiatric patients, and to better address tobacco use through the ATTOC intervention model in the context of China. METHODS: The study was conducted in Mental Health Center of West China Hospital in 2010. A total of 100 hospitalized psychiatric patients were recruited to carry out ATTOC intervention. Subjects suffers from mental illness were diagnosed by professional psychiatrists according to the International Statistical Classification of Diseases (ICD-10) criteria. RESULTS: The prevalence of tobacco use in hospitalized psychiatric patients were closely correlated with the type of mental illness, family smoking history, sex, age, marital status, education status, etc. However, most psychiatric patients knew little about these, and tended to ignore the importance of smoking cessation. CONCLUSIONS: The ATTOC intervention program of the U.S. may be suitable for hospitalized Chinese psychiatric patients, and it could be applied for the tobacco smoking treatment in China. However, the health effects of tobacco use still did not draw amount attentions from both the clinicians and general public. It is urgently needed to raise people\u27s awareness and carry out ATTOC intervention to control tobacco use, and ultimately terminate tobacco use

Altered expression of circadian clock gene, mPer1, in mouse brain and kidney under morphine dependence and withdrawal

Every physiological function in the human body exhibits some form of circadian rhythmicity. Under pathological conditions, however, circadian rhythmicity may be dusrupted. Patients infected with HIV or addicted to drugs of abuse often suffer from sleep disorders and altered circadian rhythms. Early studies in Drosophila suggested that drug seeking behavior might be related to the expression of certain circadian clock genes. Our previous research showed that conditioned place preference with morphine treatment was altered in mice lacking the Period-1 (mPer1) circadian clock gene. Thus, we sought to investigate whether morphine treatment could alter the expression of mPer1, especially in brain regions outside the SCN and in peripheral tissues. Our results using Western blot analysis showed that the mPER1 immunoreactivity exhibited a strong circadian rhythm in the brains of the control (Con), morphine-dependent (MD), and morphine-withdrawal (MW) mice. However, the phase of the circadian rhythm of mPER1 expression in the brains of MD mice significantly differed from that of the Con mice (p < 0.05). In contrast to mPER1 expression in the brain, the circadian rhythm of mPER1 immunoreactivity in the kidneys was abolished after morphine administration, whereas the Con mice maintained robust circadian rhythmicity of mPER1 in the kidney. Therefore, the effect of morphine on the circadian clock gene mPer1 may vary among different organs, resulting in desynchronization of circadian function between the SCN and peripheral organs. Originally published Journal of Circadian Rhythms, Vol. 4, No. 9, Aug 2006

A High‐resolution Atmospheric Dust Record for 1810–2004 A.D. Derived from an Ice Core in Eastern Tien Shan, Central Asia

Centennial‐scale, high‐resolution records of atmospheric dust conditions are rare in the arid and semiarid regions of central Asia, limiting our understanding of the regional climate and environmental changes and their potential driving forces. In this paper, we present an annually resolved atmospheric dust record covering the period of 1810–2004 A.D., reconstructed from an ice core retrieved at 4512 m above sea level from the Miaoergou Glacier in the eastern Tien Shan. The time series of dust flux for the past 195 years shows three periods of relatively low values (i.e., 1810–1829 A.D., 1863–1940 A.D., and 1979–2004 A.D.) and two periods of relatively high values (i.e., 1830–1862 A.D. and 1941–1978 A.D.). Spatial correlation analysis suggests possible regional factors controlling the dust flux, including antecedent summer precipitation, spring soil moisture, and near‐surface wind speed. In addition, the Miaoergou dust flux is closely associated with the winter index of the North Atlantic Oscillation (NAO) over the past two centuries, with high (low) dust periods coinciding with the negative (positive) phases of the NAO. The persistent relationship suggests that the NAO may have been a key driver on dust flux change over the arid regions between the Tien Shan and Kunlun Mountains

Controlling shear band instability by nanoscale heterogeneities in metallic nanoglasses

Strain localization during plastic deformation drastically reduces the shear band stability in metallic glasses, ultimately leading to catastrophic failure. Therefore, improving the plasticity of metallic glasses has been a long-standing goal for several decades. In this regard, nanoglass, a novel type of metallic glass, has been proposed to exhibit differences in short and medium range order at the interfacial regions, which could promote the formation of shear transformation zones. In the present work, by introducing heterogeneities at the nanoscale, both crystalline and amorphous, significant improvements in plasticity are realized in micro-compression tests. Both amorphous and crystalline dispersions resulted in smaller strain bursts during plastic deformation. The yield strength is found to increase significantly in Cu–Zr nanoglasses compared to the corresponding conventional metallic glasses. The reasons for the mechanical behavior and the importance of nanoscale dispersions to tailor the properties is discussed in detail

Visual Robotic Manipulation with Depth-Aware Pretraining

Recent work on visual representation learning has shown to be efficient for robotic manipulation tasks. However, most existing works pretrained the visual backbone solely on 2D images or egocentric videos, ignoring the fact that robots learn to act in 3D space, which is hard to learn from 2D observation. In this paper, we examine the effectiveness of pretraining for vision backbone with public-available large-scale 3D data to improve manipulation policy learning. Our method, namely Depth-aware Pretraining for Robotics (DPR), enables an RGB-only backbone to learn 3D scene representations from self-supervised contrastive learning, where depth information serves as auxiliary knowledge. No 3D information is necessary during manipulation policy learning and inference, making our model enjoy both efficiency and effectiveness in 3D space manipulation. Furthermore, we introduce a new way to inject robots' proprioception into the policy networks that makes the manipulation model robust and generalizable. We demonstrate in experiments that our proposed framework improves performance on unseen objects and visual environments for various robotics tasks on both simulated and real robots.Comment: submitted to ICRA202