105 research outputs found
Translating XPS Measurement Procedure for Band Alignment into Reliable Ab-initio Calculation Method
Band alignment between solids is a crucial issue in condensed matter physics
and electronic devices. Although the XPS method has been used as a routine
method for determination of the band alignment, the theoretical calculations by
copying the XPS band alignment procedure usually fail to match the measured
results. In this work, a reliable ab-initio calculation method for band
alignment is proposed on the basis of the XPS procedure and in consideration of
surface polarity and lattice deformation. Application of our method to anatase
and rutile TiO2 shows well agreement between calculation and experiment.
Furthermore, our method can produce two types of band alignment: the coupled
and the intrinsic, depending on whether the solid/solid interface effect is
involved or not. The coupled and intrinsic band alignments correspond to
alignments measured by XPS and electrochemical impedance analysis,
respectively, explaining why band alignments reported by these two experiments
are rather inconsistent
Zoonosis at the Huanan Seafood Market: A Critique
Since the Hunan Seafood Market (HSM) in Wuhan, China was first suggested as the source of the COVID-19 pandemic in late January 2020, debate has continued over the evidence supporting this claim. Here, we assess the evidence provided in support of zoonotic spillover at the HSM as the origin of human infection of SARS-CoV-2. We find that the datasets and analyses put forward in support of zoonosis are biased, and lack sufficient verifiable data to support this hypothesis. The earliest COVID-19 case at the HSM was not at or near a wildlife stall, the distribution of cases at the HSM is consistent with a Poisson point process model (randomly distributed) and the distribution of wildlife stalls and COVID-19 cases are consistent with independent Poisson point processes. No statistical correlation is found between cases and wildlife stall locations. The random distribution of cases and several isolated clusters is consistent with human-to-human transmission in shared areas such as eating areas, toilets and social gathering areas. Sampling bias is evident in specimen collection at the market, with over-sampling evident in the SW corner of the market relative to the rest of the market. Notwithstanding this bias, environmental positive PCR samples are more consistent with contamination by infected COVID-19 cases and aerosol spread from the HSM toilets, as compared with from wildlife stalls. Although proposed as the intermediate spillover host, raccoon dogs were unlikely to be linked with the outbreak, as they were sold in Wuhan in small numbers, and there is no epidemiological evidence indicating any infection of a raccoon dog, or any other wild or domestic animal, before or during the early pandemic, at any market elsewhere in Wuhan, or even in the rest of China. These considerations indicate that HSM was instead likely a superspreader location, with only tenuous evidence to support a zoonotic spillover there. Consequently, we conclude there is sufficient evidence to indicate the HSM as the source of the pandemic
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