Digital coding metasurfaces have attracted considerable interest, owing to their ability to manipulate electromagnetic waves and implement various functionalities with programmable controls. These metasurfaces offer high‐resolution and high‐speed responses; thus, they are implemented in high‐speed imaging, nondestructive sensing, and wireless communication. However, traditional active metasurfaces are typically based on semiconductor components, which are difficult to realize at terahertz frequencies. Additionally, non‐magnetic transmissive metasurfaces cannot realize a large phase‐tuning range without increasing the number of metasurface layers. Herein, a 1‐bit transmissive digital coding metasurface based on liquid crystals is proposed to achieve programmable terahertz beam manipulations with electric control. The Fano resonance that is excited in the asymmetrical metasurface element enables a larger phase variation while maintaining the transmittance. The proposed digital metasurface can effectively achieve many functionalities, such as dual beam steering, multiple beams, and orbital angular momentum beams, via altered coding patterns; an example of dual beam steering is experimentally verified. This study is expected to provide a promising method to manipulate transmissive terahertz beams using a digitally programmable metasurface, and it has potential applications in imaging, sensing, and wireless communications.

Fibroblast growth factor 5 (FGF5) regulates hair length in humans and a variety of other animals. To investigate whether FGF5 has similar effects in sheep, we used clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) to generate loss-of-function mutations with the FGF5 gene in Chinese Merino sheep. A total of 16 lambs were identified with genetic mutations within the targeting locus: 13 lambs had biallelic modifications and three lambs had monoallelic modifications. Characterization of the modifications revealed that 13 were frameshift mutations that led to premature termination, whereas the other three were inframe deletions. Thus, CRISPR/Cas9 efficiently generated loss-of-function mutations in the sheep FGF5 gene. We then investigated the effect of loss of FGF5 function on wool traits in 12 lambs and found that wool staple length and stretched length of genetically modified (GM) yearling sheep were significantly longer compared with that of wild-type (WT) control animals. The greasy fleece weight of GM yearling sheep was also significantly greater compared with that of WT sheep. Moreover, the mean fiber diameter in GM sheep showed no significant difference compared with WT sheep, suggesting that the increase in greasy fleece weight was likely attributed to the increase in wool length. The results of this study suggest that CRISPR/Cas9-mediated loss of FGF5 activity could promote wool growth and, consequently, increase wool length and yield.

Background Until January 18, 2021, coronavirus disease-2019 (COVID-19) has infected more than 93 million individuals and has caused a certain degree of panic. Viral pneumonia caused by common viruses such as respiratory syncytial virus, rhinovirus, human metapneumovirus, human bocavirus, and parainfluenza viruses have been more common in children. However, the incidence of COVID-19 in children was significantly lower than that in adults. The purpose of this study was to describe the clinical manifestations, treatment and outcomes of COVID-19 in children compared with those of other sources of viral pneumonia diagnosed during the COVID-19 outbreak. Methods Children with COVID-19 and viral pneumonia admitted to 20 hospitals were enrolled in this retrospective multi-center cohort study. A total of 64 children with COVID-19 were defined as the COVID-19 cohort, of which 40 children who developed pneumonia were defined as the COVID-19 pneumonia cohort. Another 284 children with pneumonia caused by other viruses were defined as the viral pneumonia cohort. The epidemiologic, clinical, and laboratory findings were compared by Kolmogorov-Smirnov test, t-test, Mann-Whitney U test and Contingency table method. Drug usage, immunotherapy, blood transfusion, and need for oxygen support were collected as the treatment indexes. Mortality, intensive care needs and symptomatic duration were collected as the outcome indicators. Results Compared with the viral pneumonia cohort, children in the COVID-19 cohort were mostly exposed to family members confirmed to have COVID-19 (53/64 vs. 23/284), were of older median age (6.3 vs. 3.2 years), and had a higher proportion of ground-glass opacity (GGO) on computed tomography (18/40 vs. 0/38, P < 0.001). Children in the COVID-19 pneumonia cohort had a lower proportion of severe cases (1/40 vs. 38/284, P = 0.048), and lower cases with high fever (3/40 vs. 167/284, P < 0.001), requiring intensive care (1/40 vs. 32/284, P < 0.047) and with shorter symptomatic duration (median 5 vs. 8 d, P < 0.001). The proportion of cases with evaluated inflammatory indicators, biochemical indicators related to organ or tissue damage, D-dimer and secondary bacterial infection were lower in the COVID-19 pneumonia cohort than those in the viral pneumonia cohort (P < 0.05). No statistical differences were found in the duration of positive PCR results from pharyngeal swabs in 25 children with COVID-19 who received antiviral drugs (lopinavir-ritonavir, ribavirin, and arbidol) as compared with duration in 39 children without antiviral therapy [median 10 vs. 9 d, P = 0.885]. Conclusion The symptoms and severity of COVID-19 pneumonia in children were no more severe than those in children with other viral pneumonia. Lopinavir-ritonavir, ribavirin and arbidol do not shorten the duration of positive PCR results from pharyngeal swabs in children with COVID-19. During the COVID-19 outbreak, attention also must be given to children with infection by other pathogens infection.

A programmable metasurface antenna based on electrically tunable elements operating in 5G millimeter‐wave band, which has the features of low cost, easy manufacturing, low profile, easy integration with planar circuits, is proposed herein. The prototype consists of a 128‐element metasurface array, an 8‐channel beamforming chip as equal amplitude power divider networks, and a control network. Elements mounted with varactors to realize different states are controlled by DC bias signal from the back of a printed circuit board (PCB). By assigning different voltage values, array coding can be dynamically changed, thereby realizing beam steering. Both element dimensions and its location along substrate integrated waveguide (SIW) are optimized to better antenna performance. Experiment results show that the proposed metasurface can achieve not only the scanning range of ±70° for unidirectional beam in azimuth and ±40° in elevation but also ±50° for dual beam in azimuth. The whole prototype is fabricated based on PCB technologies, and good agreements among simulated and measured results are obtained. The proposed electrically tunable metasurface array is a good alternative to the traditional expensive phased array and has a great potential application prospect in radar and communication systems.

A modified high Cr ferritic heat-resistant steel was developed and subjected to the thermomechanical treatment. The effect of applied stress and temperature on martensitic transformation and microstructure was studied by using high-resolution differential dilatometer and optical microscope. Applied stress raises the amount of defection as dislocation and grain boundary defects, thus elevateMs. Applied stress also lead to the increase of transformation time due to the mechanical stabilization of austenite. Increase of applied stress or temperature would enhance these above effects.