Coronavirus disease 2019 , which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic in the past four months and causes respiratory disease in humans of almost all ages. Although several drugs have been announced to be partially effective treatments for this disease, no approved vaccine is available. Here, we described the construction of a recombinant Lactobacillus plantarum strain expressing the SARS-CoV-2 spike protein. The results showed that the spike gene with optimized codons could be efficiently expressed on the surface of recombinant L. plantarum and exhibited high antigenicity. The highest protein yield was obtained under the following conditions: cells were induced with 50 ng/mL SppIP at 37°C for 6-10 h. The recombinant spike (S) protein was stable under normal conditions and at 50°C, pH = 1.5, or a high salt concentration. Recombinant L. plantarum may provide a promising foodgrade oral vaccine candidate against SARS-CoV-2 infection.
The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.
Zhun
Dong (ZD) coal, which is characterized by high sodium levels, was
burned in a pilot-scale furnace to investigate the behavior of fouling
deposits on an oil-cooled probe with different surface temperatures.
In this study, the fouling deposits were collected at 1298 K furnace
temperature. In addition, the inlet temperatures of the conduction
oil were set as 543, 493, and 443 K, which were comparable to the
feedwater temperature in the coal-fired boiler economizer. The surface
temperatures of the deposition probe varied in the ranges of 733–594,
714–571, and 671–507 K. A digital imaging technique
was used to monitor variations in deposit thickness and deposit morphology
over time for the three cases. The results revealed that the probe
surface temperature had a significant effect on the growth, mineralogy,
and microstructure of the fouling deposit. The stable thicknesses
of the three fouling deposits fluctuated in the ranges of 9.63–9.82,
12.48–12.54, and 15.31–15.53 mm in the 543, 493, and
443 K cases, respectively. In addition, a low probe surface temperature
resulted in the absence of significant sintering in the fouling deposit
for the 443 K case.
This
paper presents the measurement of effective heat conductivity
of ash deposit based on a novel technique for Zhun Dong coal (ZD)
with high sodium in a pilot scale furnace. The variation of deposit
thickness with time is determined by digital image technique. In addition,
simplified two color method is applied to obtain the deposit surface
temperature. Subsequently, the change of the average effective heat
conductivity of the ash deposit with deposit growth is calculated
by combining the deposit surface temperature and thickness. Meanwhile,
mineral phases of the ash deposits were identified by X-ray diffraction
spectrometry (XRD); scanning electron microscopy (SEM) was applied
to analyze the microstructure of ash deposit, and the corresponding
chemical compositions were determined by energy dispersive X-ray spectrometry
(EDX). The growth process of the ash deposit on probe 2 was composed
of four stages based on digital image technique. This was confirmed
by the layer structures of the slagging deposits. In addition, the
deposit surface temperature increased with time, and it finally fluctuated
around 1255 °C. Meanwhile, the results showed that the average
effective heat conductivity of the ash deposit on probe 2 increased
linearly with deposit growth. The XRD analysis results of three deposits
showed that these deposits had similar mineralogy in every layer structure.
The content of gehlenite in the deposit increased with the deposit
growth. Moreover, the loss of glass is accompanied by a corresponding
increase in crystalline phase.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.