Tunable amount of monatomic and nanoscale Pt clusters were trapped in TiO2 and CeO2 nanowires via a generic one-step dealloying approach from designed Al-Ti-Pt and Al-Ce-Pt precursor alloys. It was ...demonstrated that the doped Pt were in the form of both single atoms and Pt clusters stabilized in TiO2 or CeO2 nanowires. Electrochemical tests manifested that these highly dispersed Pt doped metal oxide greatly enhanced the utilization efficiency of noble metals. When used as an electrocatalyst for the methanol oxidation reaction (MOR) or hydrogen evolution reaction (HER), the Pt-TiO2 or Pt-CeO2 catalysts after activation exhibited much higher catalytic activity and stability as compared to the commercial Pt/C catalyst. The highest mass activity of the Pt0.2-TiO2 catalysts obtained from dealloying Al85Ti14.8Pt0.2 reached 1200 mA mg−1 for MOR, more than six times higher than that of Pt/C. The mass activity of the Pt0.2-CeO2 for HER is around 50 times that of Pt/C. With clear advantages of low costs, simple fabrication procedure, and enhanced catalytic performance, these Pt-metal oxide nanowires can be suitable for many catalytic reactions.
•A general top-down dealloying strategy is developed to stabilize single Pt atoms and clusters in TiO2 and CeO2 nanowires.•After activation, the Pt-doped TiO2 exhibit much enhanced mass activity for methanol electro-oxidation.•Due to the stabilization effect of metal oxides, the Pt-doped catalysts are highly stable for electrocatalysis.
Minimally invasive right posterior sectionectomy (RPS) is a technically challenging procedure. This study was designed to determine outcomes following robotic RPS (R-RPS) and laparoscopic RPS ...(L-RPS).
An international multicentre retrospective analysis of patients undergoing R-RPS versus those who had purely L-RPS at 21 centres from 2010 to 2019 was performed. Patient demographics, perioperative parameters, and postoperative outcomes were analysed retrospectively from a central database. Propensity score matching (PSM) was performed, with analysis of 1 : 2 and 1 : 1 matched cohorts.
Three-hundred and forty patients, including 96 who underwent R-RPS and 244 who had L-RPS, met the study criteria and were included. The median operating time was 295 minutes and there were 25 (7.4 per cent) open conversions. Ninety-seven (28.5 per cent) patients had cirrhosis and 56 (16.5 per cent) patients required blood transfusion. Overall postoperative morbidity rate was 22.1 per cent and major morbidity rate was 6.8 per cent. The median postoperative stay was 6 days. After 1 : 1 matching of 88 R-RPS and L-RPS patients, median (i.q.r.) blood loss (200 (100-400) versus 450 (200-900) ml, respectively; P < 0.001), major blood loss (> 500 ml; P = 0.001), need for intraoperative blood transfusion (10.2 versus 23.9 per cent, respectively; P = 0.014), and open conversion rate (2.3 versus 11.4 per cent, respectively; P = 0.016) were lower in the R-RPS group. Similar results were found in the 1 : 2 matched groups (66 R-RPS versus 132 L-RPS patients).
R-RPS and L-RPS can be performed in expert centres with good outcomes in well selected patients. R-RPS was associated with reduced blood loss and lower open conversion rates than L-RPS.
Supermassive black hole binaries (SMBHBs) are products of galaxy mergers, and are important in testing LAMBDA cold dark matter cosmology and locating gravitational-wave-radiation sources. A unique ...electromagnetic signature of SMBHBs in galactic nuclei is essential in identifying the binaries in observations from the IR band through optical to X-ray. Recently, the flares in optical, UV, and X-ray caused by supermassive black holes (SMBHs) tidally disrupting nearby stars have been successfully used to observationally probe single SMBHs in normal galaxies. In this Letter, we investigate the accretion of the gaseous debris of a tidally disrupted star by a SMBHB. Using both stability analysis of three-body systems and numerical scattering experiments, we show that the accretion of stellar debris gas, which initially decays with time propor tot {sup -5/3}, would stop at a time T{sub tr} approx = etaT{sub b}. Here, eta approx 0.25 and T{sub b} is the orbital period of the SMBHB. After a period of interruption, the accretion recurs discretely at time T{sub r} approx = xi{sub b}, where xi approx 1. Both eta and xi sensitively depend on the orbital parameters of the tidally disrupted star at the tidal radius and the orbit eccentricity of SMBHB. The interrupted accretion of the stellar debris gas gives rise to an interrupted tidal flare, which could be used to identify SMBHBs in non-active galaxies in the upcoming transient surveys.
Growing evidence suggests that Type Iax supernovae might be the result of thermonuclear deflagrations of Chandrasekhar-mass white dwarfs in binary systems. We carry out Monte Carlo radiative transfer ...simulations and predict spectropolarimetric features originating from the supernova explosion and subsequent ejecta interaction with the companion star. Specifically, we calculate viewing-angle dependent flux and polarisation spectra for a 3D model simulating the deflagration of a Chandrasekhar-mass white dwarf and, for a second model, simulating the ejecta interaction with a main-sequence star. We find that the intrinsic signal is weakly polarised and only mildly viewing-angle dependent, owing to the overall spherical symmetry of the explosion and the depolarising contribution of iron-group elements dominating the ejecta composition. The interaction with the companion star carves out a cavity in the ejecta and produces a detectable, but modest signal that is significant only at relatively blue wavelengths (≲5000 Å). In particular, increasingly fainter and redder spectra are predicted for observer orientations further from the cavity, while a modest polarisation signal
P
~ 0.2 per cent is found at blue wavelengths for orientations 30° and 45° away from the cavity. We find a reasonable agreement between the interaction model viewed from these orientations and spectropolarimetric data of SN 2005hk and interpret the maximum-light polarisation signal seen at blue wavelengths for this event as a possible signature of the ejecta–companion interaction. We encourage further polarimetric observations of SNe Iax to test whether our results can be extended and generalised to the whole SN Iax class.
Daily PM
2.5 and water-soluble inorganic ions (Na
+, NH
4
+, K
+, Mg
2+, Ca
2+, Cl
−, NO
3
− and SO
4
2−) were collected in Xi'an (34.23°N, 108.88°E), China from March 2006 to March 2007. PM
2.5 was ...collected using battery-powered mini-volume samplers. And the ions were determined by ion chromatography from the measured aerosol mass. The annual average mass concentration of PM
2.5 was found to be 194.1
±
78.6
μg
m
−
3
, which exceeded substantially the international guidelines for health concerns. The seasonal average mass concentration of PM
2.5 was highest in winter (266.8
μg
m
−
3
) and lowest in summer (138.6
μg
m
−
3
). The three highest abundant ions were SO
4
2−, NO
3
−, and NH
4
+, with average concentrations of 35.6
±
19.5
μg
m
−
3
, 16.4
±
10.1
μg
m
−
3
, and 11.4
±
6.8
μg
m
−
3
, which were accounted for 18.7%, 8.0%, and 5.7% of the PM
2.5 mass, respectively. The major ions were in the species of (NH
4)
2SO
4, NH
4HSO
4 and NH
4NO
3, and their concentrations were highest in winter, due to high coal combustion. The concentrations of Ca
2+ were higher in spring than other seasons, due to the higher mineral dust concentrations. Ca
2+ was strongly correlated with CO
3
2−, which was calculated as the difference in the measured cations minus anions. Ion balance calculations indicate that the PM
2.5 was acidic, and this result is consistent with the measurement of pH values. Sulfur oxidation ratio was higher in summer and autumn, which implies that the formation of secondary sulfate-rich particles is favored by warm and relatively moist weather. Nitrogen oxidation ratio was highest in autumn.
► Coal combustion has heavy impact on the variations of water-soluble ions. ► PM
2.5 in non-spring was acidic, while the aerosol was less acidic and possibly even alkaline in spring due to the buffering effects of mineral dust. ► Relationship between CO
3
2- and Ca
2+ implies that Ca
2CO
3 was the major form for the aerosol carbonate.
Global literature has suggested a negative impact of acculturative stress on both physical and mental health among international migrants. In China, approximately 20 percent of its population is ...rural-to-urban migrant workers and there are significant cultural differences between rural and urban societies, but no data are available regarding the acculturative stress of Chinese migrant workers. This study aimed to explore the forms and contexts of acculturative stress among Chinese migrant workers.
Qualitative data were collected from four focus group discussions with 17 Chinese rural-to-urban migrant workers and three individual interviews with three medical professionals who provided mental health services for factory-workers in Shenzhen, China.
The data in the current study showed that rural-to-urban migrant workers in China had experienced various forms of acculturative stress including difficulties in adapting to the environment, work-related stress, family-related stress, financial hardship, and lack of sense of belonging to cities.
Rural-to-urban migration in China is a challenging transition with significant acculturative stress and demands for major adjustments among migrant workers. The assessment and management of acculturative stress is a necessary first step in providing mental health services to migrant workers.
Abstract
An otherwise dormant supermassive black hole (SMBH) in a galactic nucleus flares up when it tidally disrupts a star passing by. Most of the tidal disruption events (TDEs) and candidates ...discovered in the optical/UV have broad optical emission lines with complex and diverse profiles of puzzling origin. In this Letter, we show that the double-peaked broad H α line of the TDE candidate PTF09djl can be well modelled with a relativistic elliptical accretion disc and the peculiar substructures with one peak at the line rest wavelength and the other redshifted to about 3.5 × 104 km s−1 are mainly due to the orbital motion of the emitting matter within the disc plane of large inclination 88° and pericentre orientation nearly vertical to the observer. The accretion disc has an extreme eccentricity 0.966 and semimajor axis of 340 BH Schwarzschild radii. The viewing angle effects of large disc inclination lead to significant attenuation of He emission lines originally produced at large electron scattering optical depth and to the absence/weakness of He emission lines in the spectra of PTF09djl. Our results suggest that the diversities of line intensity ratios among the line species in optical TDEs are probably due to the differences of disc inclinations.
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