Hong Kong Polytechnic University

About: Hong Kong Polytechnic University is a education organization based out in Hong Kong, China. It is known for research contribution in the topics: Computer science & Tourism. The organization has 29633 authors who have published 72136 publications receiving 1956312 citations. The organization is also known as: HKPU & PolyU.

Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in China.

Abstract: Detection of asymptomatic or subclinical novel human coronavirus SARS-CoV-2 infection is critical for understanding the overall prevalence and infection potential of COVID-19. To estimate the cumulative prevalence of SARS-CoV-2 infection in China, we evaluated the host serologic response, measured by the levels of immunoglobulins M and G in 17,368 individuals, in the city of Wuhan, the epicenter of the COVID-19 pandemic in China, and geographic regions in the country, during the period from 9 March 2020 to 10 April 2020. In our cohorts, the seropositivity in Wuhan varied between 3.2% and 3.8% in different subcohorts. Seroposivity progressively decreased in other cities as the distance to the epicenter increased. Patients who visited a hospital for maintenance hemodialysis and healthcare workers also had a higher seroprevalence of 3.3% (51 of 1,542, 2.5-4.3%, 95% confidence interval (CI)) and 1.8% (81 of 4,384, 1.5-2.3%, 95% CI), respectively. More studies are needed to determine whether these results are generalizable to other populations and geographic locations, as well as to determine at what rate seroprevalence is increasing with the progress of the COVID-19 pandemic. Serologic surveillance has the potential to provide a more faithful cumulative viral attack rate for the first season of this novel SARS-CoV-2 infection.

Winter and Summer PM2.5 Chemical Compositions in Fourteen Chinese Cities

Abstract: PM2.5 in 14 of China's large cities achieves high concentrations in both winter and summer with averages >100 μg m−3 being common occurrences. A grand average of 115 μg m−3 was found for all cities, with a minimum of 27 μg m−3 measured at Qingdao during summer and a maximum of 356 μg m−3 at Xi'an during winter. Both primary and secondary PM2.5 are important contributors at all of the cities and during both winter and summer. While ammonium sulfate is a large contributor during both seasons, ammonium nitrate contributions are much larger during winter. Lead levels are still high in several cities, reaching an average of 1.68 μg m−3 in Xi'an. High correlations of lead with arsenic and sulfate concentrations indicate that much of it derives from coal combustion, rather than leaded fuels, which were phased out by calendar year 2000. Although limited fugitive dust markers were available, scaling of iron by its ratios in source profiles shows ∼20% of PM2.5 deriving from fugitive dust in most of the cities. Mult...

Fabrication of Nickel–Cobalt Bimetal Phosphide Nanocages for Enhanced Oxygen Evolution Catalysis

Abstract: Replacement of precious metals with earth-abundant electrocatalysts for oxygen evolution reaction (OER) holds great promise for realizing practically viable water-splitting systems. It still remains a great challenge to develop low-cost, highly efficient, and durable OER catalysts. Here, the composition and morphology of Ni–Co bimetal phosphide nanocages are engineered for a highly efficient and durable OER electrocatalyst. The nanocage structure enlarges the effective specific area and facilitates the contact between catalyst and electrolyte. The as-prepared Ni–Co bimetal phosphide nanocages show superior OER performance compared with Ni2P and CoP nanocages. By controlling the molar ratio of Ni/Co atoms in Ni–Co bimetal hydroxides, the Ni0.6Co1.4P nanocages derived from Ni0.6Co1.4(OH)2 nanocages exhibit remarkable OER catalytic activity (η = 300 mV at 10 mA cm−2) and long-term stability (10 h for continuous test). The density-functional-theory calculations suggest that the appropriate Co doping concentration increases density of states at the Fermi level and makes the d-states more close to Fermi level, giving rise to high charge carrier density and low intermedia adsorption energy than those of Ni2P and CoP. This work also provides a general approach to optimize the catalysis performance of bimetal compounds.