ABSTRACT
A nanoscale on-chip light source with high intensity is desired for various applications in integrated photonics systems. However, it is challenging to realize such an emitter using materials and fabrication processes compatible with the standard integrated circuit technology. In this letter, we report an electrically driven Si light-emitting diode with sub-wavelength emission area fabricated in an open-foundry microelectronics complementary metal-oxide-semiconductor platform. The light-emitting diode emission spectrum is centered around 1100 nm and the emission area is smaller than 0.14 µm2 (~[Formula: see text] nm). This light-emitting diode has high spatial intensity of >50 mW/cm2 which is comparable with state-of-the-art Si-based emitters with much larger emission areas. Due to sub-wavelength confinement, the emission exhibits a high degree of spatial coherence, which is demonstrated by incorporating the light-emitting diode into a compact lensless in-line holographic microscope. This centimeter-scale, all-silicon microscope utilizes a single emitter to simultaneously illuminate ~9.5 million pixels of a complementary metal-oxide-semiconductor imager.
ABSTRACT
Objective@#To learn the epidemiological characteristics of coronavirus disease 2019(COVID-19)clusters in Nanning,Guangxi Province,so as to provide reference for the prevention and control of COVID-19. @*Methods@#The data of COVID-19 clusters from January to February,2020 in Nanning were collected through the Public Emergency Response System of National CDC. Descriptive epidemiological analysis were conducted to analyze the time,space and population distribution, source of infection,transmission chain, ways of detection and the scale of clusters. @*Results@#Eleven clusters were reported,with 36 confirmed cases and 293 exposed persons. The average attack rate was 12.29%. There were ten family clusters. The epidemic scale was small,with an average of 3.27 cases. The onset of cases peaked on January 23,while the reporting time was mainly from February 10 to February 18. The cases were distributed in two cities and one county. The attack rate of Qingxiu District and Xixiangtang District was 16.95%,which was higher than 5.17% of Mashan County(p<0.05). The recurrence rate of family contacts was 25.42%,which was higher than that of other ways of contacts(p<0.05). Of eleven clusters,nine were caused by imported cases or related cases;five developed secondary cases or above,and the median interval between the first and secondary cases was three days.@*Conclusions@#The COVID-19 clusters in Nanning occurred mainly in families with small scales and most were caused by imported cases. The majority of the cases were reported during mid February. The attack rate in urban areas was higher than that in rural areas.
ABSTRACT
The Michaelis-Menten constant Km is a very important parameter to relate enzyme with its substrate in enzymatic reaction. Although Km can be experimentally determined, the Km values are not easily available in literature. With rapid increase of newly designed enzymes, we face the shortage of parameters related to enzymatic reactions. The beta-glucosidase is a crucial enzyme for cellulose hydrolysis and cellobiose is one of its substrates. In this study, we attempt to develop models to predict Km with cellobiose as substrates using information about primary structure of beta-glucosidase. The results show that the 20-1 feedforward backpropagation neural network using the amino-acid distribution probability as predictor works best for prediction of Km values.
