Objective: This study investigated the influence of Coronavirus Disease 2019 (COVID-19) on lung function in early convalescence phase. Methods: A retrospective study of COVID-19 patients at the Fifth Affiliated Hospital of Sun Yat-sen University were conducted, with serial assessments including lung volumes (TLC), spirometry (FVC, FEV1), lung diffusing capacity for carbon monoxide (DLCO),respiratory muscle strength, 6-min walking distance (6MWD) and high resolution CT being collected at 30 days after discharged.Results: Fifty-seven patients completed the serial assessments. There were 40 non-severe cases and 17 severe cases. Thirty-one patients (54.3%) had abnormal CT findings. Abnormalities were detected in the pulmonary function tests in 43 (75.4%) of the patients. Six (10.5%), 5(8.7%), 25(43.8%) 7(12.3%), and 30 (52.6%) patients had FVC, FEV1, FEV1/FVC ratio, TLC, and DLCO values less than 80% of predicted values, respectively. 28 (49.1%) and 13 (22.8%) patients had PImax and PEmax values less than 80% of the corresponding predicted values. Compared with non-severe cases, severe patients showed higher incidence of DLCO impairment (75.6%vs42.5%, p = 0.019), higher lung total severity score (TSS) and R20, and significantly lower percentage of predicted TLC and 6MWD. No significant correlation between TSS and pulmonary function parameters was found during follow-up visit. Conclusion: Impaired diffusing-capacity, lower respiratory muscle strength, and lung imaging abnormalities were detected in more than half of the COVID-19 patients in early convalescence phase. Compared with non-severe cases, severe patients had a higher incidence of DLCO impairment and encountered more TLC decrease and 6MWD decline.
Spintronic devices based on antiferromagnetic (AFM) materials hold the promise of fast switching speeds and robustness against magnetic fields 1-3 . Different device concepts have been predicted 4,5 and experimentally demonstrated, such as low-temperature AFM tunnel junctions that operate as spin-valves 6 , or roomtemperature AFM memory, for which either thermal heating in combination with magnetic fields 7 , or Néel spin-orbit torque 8 is used for the information writing process. On the other hand, piezoelectric materials were employed to control magnetism by electric fields in multiferroic heterostructures 9-12 , which suppresses Joule heating caused by switching currents and may enable low energy-consuming electronic devices. Here, we combine the two material classes to explore changes of the resistance of the high-Néel-temperature antiferromagnet MnPt induced by piezoelectric strain. We find two non-volatile resistance states at room temperature and zero electric field, which are stable in magnetic fields up to 60 T. Furthermore, the strain-induced resistance switching process is insensitive to magnetic fields. Integration in a tunnel junction can further amplify the electroresistance. The tunneling anisotropic magnetoresistance reaches ~11.2% at room temperature. Overall, we demonstrate a piezoelectric, strain-controlled AFM memory which is fully operational in strong magnetic fields and has potential for low-energy and high-density memory applications.
In recent years, the field of antiferromagnetic spintronics has been substantially advanced. Electric‐field control is a promising approach for achieving ultralow power spintronic devices via suppressing Joule heating. Here, cutting‐edge research, including electric‐field modulation of antiferromagnetic spintronic devices using strain, ionic liquids, dielectric materials, and electrochemical ionic migration, is comprehensively reviewed. Various emergent topics such as the Néel spin–orbit torque, chiral spintronics, topological antiferromagnetic spintronics, anisotropic magnetoresistance, memory devices, 2D magnetism, and magneto‐ionic modulation with respect to antiferromagnets are examined. In conclusion, the possibility of realizing high‐quality room‐temperature antiferromagnetic tunnel junctions, antiferromagnetic spin logic devices, and artificial antiferromagnetic neurons is highlighted. It is expected that this work provides an appropriate and forward‐looking perspective that will promote the rapid development of this field.
antiferromagnet involves the antiferromagnetic exchange field H E as well due to spin canting via ω AFM ≈ ≈ 2 E A SF r H H rH , where r is the gyromagnetic ratio of an electron. It can be three orders of magnitude higher than that of ferromagnets ω FM ≈ rH A (typically GHz) and reaches THz. For example, the study on the laser-induced spin reorientation in antiferromagnetic TmFeO 3 in 2004 shows that the antiferromagnetic spins can be manipulated on a timescale of a few picoseconds. [1] In 2006, Núñes et al. proposed a pioneering theory that spin transfer torques can induce the order parameter orientation switching in antiferromagnetic metals, which is well similar to the ferromagnetic case. [2] However, they pointed out that compared with the ferromagnetic case, the critical current for antiferromagnetic order parameter switching can be smaller because of the absence of shape anisotropy and also because spin torques can act through the entire volume of an antiferromagnet. On the other hand, as the magnetic order in an antiferromagnet is staggered, only correspondingly staggered torques can drive coherent order parameter switching. Soon in 2007, different experimental groups demonstrated that the exchange bias of a ferromagnet/antiferromagnet bilayer system can be altered by a current and thus provided indirect evidences for current-induced torques in antiferromagnetic metals. [3][4][5] Subsequently, Gomonaȋand Loktev proposed the phenomenological model that describes the spin transfer torques in antiferromagnets. [6,7] These early studies were summarized by MacDonald and Tsoi in the review paper that emphasizes the concept of antiferromagnetic metal spintronics [8] and also by Gomonay and Loktev in the review paper that emphasizes spintronics of antiferromagnetic systems from a theoretical point of view. [9] In 2011, Park et al. creatively reversed the stacking order of the antiferromagnetic layer IrMn and the ferromagnetic layer NiFe in a spin-valve-like tunnel junction structure, where the antiferromagnetic IrMn served as the key functional layer for generating tunnel anisotropic magnetoresistance, while the ferromagnetic NiFe layer was utilized to rotate the antiferromagnetic spin axis of IrMn via the interfacial exchange spring effect. [10] Surprisingly, a more than 100% tunneling anisotropic magnetoresistance was achieved at 4 K. This device proves that antiferromagnetic materials could work as pivotal components in spintronic devices instead of simply serving as pinning Antiferromagnets naturally exhibit three obvious advantages over ferromagnets for memory device applications: insensitivity to external magnetic fields, much faster spin dynamics (≈THz), and higher packing density due to the absence of any stray field. Recently, antiferromagnetic spintronics has emerged as a cutting-edge field in the magnetism community.The key mission of this rapidly rising field is to steer the spins or spin axes of antiferromagnets via external stimuli and then realize advanced devices based on their physical property cha...
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