Coronavirus disease is an emerging infection caused by a novel coronavirus that is moving rapidly. High resolution computed tomography (CT) allows objective evaluation of the lung lesions, thus enabling us to better understand the pathogenesis of the disease. With serial CT examinations, the occurrence, development, and prognosis of the disease can be better understood. The imaging can be sorted into four phases: early phase, progressive phase, severe phase, and dissipative phase. The CT appearance of each phase and temporal progression of the imaging findings are demonstrated.

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Utilizing individual atoms or molecules as functional units in electronic circuits meets the increasing technical demands for the miniaturization of traditional semiconductor devices. To be of technological interest, these functional devices should be high-yield, consume low amounts of energy, and operate at room temperature. In this study, we developed nanodevices called quantized conductance atomic switches (QCAS) that satisfy these requirements. The QCAS operates by applying a feedback-controlled voltage to a nanoconstriction within a stretched nanowire. We demonstrated that individual metal atoms could be removed from the nanoconstriction and that the removed metal atoms could be refilled into the nanoconstriction, thus yielding a reversible quantized conductance switch. We determined the key parameters for the QCAS between the "on" and "off" states at room temperature under a small operating voltage. By controlling the applied bias voltage, the atoms can be further completely removed from the constriction to break the nanowire, generating single-atom nanogaps. These atomic nanogaps are quite stable under a sweeping voltage and can be readjusted with subangstrom accuracy, thus fulfilling the requirement of both reliability and flexibility for the high-yield fabrication of molecular devices.

The rectifying properties in dipyrimidinyl-diphenyl co-oligomer diodes with asymmetric anchoring groups were investigated using density functional theory combined with the nonequilibrium Green’s function method. Effects of asymmetric interfaces caused by both the anchoring groups and/or contact geometries of electrodes have been investigated. Our results showed that the rectifying behavior of the co-oligomer diode could be reversed or largely enhanced by adjusting asymmetric anchoring groups. Whether the asymmetric contact geometries play a positive or negative role in improving the rectifying behavior is closely related to each molecular diode. The mechanism of modulation was analyzed in terms of molecular projected self-consistent Hamiltonian states and transmission spectra. The theoretical simulations are helpful for understanding recent experimental results [Lee et al. Langmuir 2009, 25, 1495 and Hihath et al. ACS Nano 2011, 5, 8331]. Moreover, the mechanism of the rectification only due to the electrode asymmetry was explained, and a single-molecule diode with significant rectifying behaviors has been theoretically designed.