Vaccination and Quarantine Effect on COVID-19 Transmission Dynamics Incorporating Chinese-Spring-Festival Travel Rush: Modeling and Simulations.

The COVID-19 pandemic has adversely affected the entire world. The effective implementation of vaccination strategy is critical to prevent the resurgence of the pandemic, especially during large-scale population migration. We establish a multiple patch coupled model based on the transportation network among the 31 provinces in China, under the combined strategies of vaccination and quarantine during large-scale population migration. Based on the model, we derive a critical quarantine rate to control the pandemic transmission and a vaccination rate to achieve herd immunity. Furthermore, we evaluate the influence of passenger flow on the effective reproduction number during the Chinese-Spring-Festival travel rush. Meanwhile, the spread of the COVID-19 pandemic is investigated for different control strategies, viz. global control and local control. The impact of vaccine-related parameters, such as the number, the effectiveness and the immunity period of vaccine, are explored. It is believed that the articulated models as well as the presented simulation results could be beneficial to design of feasible strategies for preventing COVID-19 transmission during the Chinese-Spring-Festival travel rush or the other future events involving large-scale population migration.

Association between tumor morphology and dosimetric parameters of organs at risk after intensity-modulated radiotherapy in esophagus cancer.

PURPOSE: We explored the effects of geometrical topological properties of tumors such as tumor length and "axial cross-sectional area (ACSA)" of tumors (planning target volume [PTV] volume /PTV length) on the dosimetric parameters of organs at risk (lung and heart) in patients with esophagus cancer (EPC) treated by way of intensity-modulated radiation therapy (IMRT), so as to provide a guideline for the dosimetric limitation for organs at risk in IMRT treatment. METHODS: A retrospective analysis was done on 103 cases of patients with EPC who were treated by IMRT from November 2010 to August 2019, in which PTV-G stood for the externally expanded planning target volume (PTV) of the gross tumor volume (GTV) and PTV-C for the externally expanded volume of the clinical target volume (CTV). A linear regression model was employed to analyze the several pairs of correlation: the 1st one between the relative length of tumors (PTV length/lung length) and pulmonary dose-volume parameters, the 2nd one between ACSA of tumors and pulmonary dose-volume parameters, the 3rd one between PTV length and the dosimetric parameters of the heart, and the last one between ACSA of tumors and the dosimetric parameters of the heart. RESULTS: (i) There was a strong positive correlation between the relative length of tumors (PTV length/lung length) and V5 (p < 0.001, r = 0.73), and V10 (p < 0.001, r = 0.66) of the lung. There was a moderate positive correlation between the relative length of tumors and V30 (p < 0.001, r = 0.44) of the lung, and a weak positive correlation between the relative length of tumors and V20 (p < 0.001, r = 0.39) of the lung. (ii) There was a strong positive correlation between ACSA of tumors (PTV volume/PTV length) and V30 (p < 0.001, r = 0.67) of the lung, a moderate positive correlation between ACSA of tumors and V20 (p <0.001, r = 0.51) of the lung, and a weak positive correlation between ACSA of tumors and V10 (p = 0.019, r = 0.23) of the lung, yet there was not an obvious correlation between ACSA of tumors and V5 p > 0.05) of the lung. (iii) There was a moderate positive correlation between PTV length and V40 (p < 0.001, r = 0.58), and Dmean (p < 0.001, r = 0.52) of the heart, yet there was no obvious correlation between ACSA of tumors and Dmean and V40 of the heart (p > 0.05). CONCLUSIONS: (i) Compared with the high-dose region of the lung, the relative length of tumors (PTV length/lung length) has a greater impact on the low-dose region of the lung. The linear regression equation of scatter plot showed that when the relative length of tumors increased by 0.1, the lung dose-volume parameters of V5 , V10 , V20 , and V30 increased by approximately 5.37%, 3.59%, 1.05%, and 1.08%, respectively. When PTV length increased by 1 cm, Dmean and V40 of the heart increased by approximately 153.6 cGy and 2.03%, respectively. (ii) Compared with the low-dose region of the lung, the value of ACSA of tumors (PTV volume/PTV length) has a greater impact on the high-dose region of the lung. However, the value of ACSA of tumors has no significant effect on the dosimetric parameters of the heart (Dmean and V40 ). The linear regression equation of scatter plot showed that when ACSA of tumors increased by 10 cm2 , the lung dose-volume parameters of V10 , V20, and V30 increased by approximately 3.11%, 3.37%, and 4.01%, respectively.

Efficient glycyrrhetinic acid biomanufacturing through protein engineering and dual-GUS combination strategy with novel ß-glucuronidase from Aspergillus calidoustus CLH-22.

Glycyrrhetinicacid (GA) is a high-value pentacyclic triterpenoid with broad applications. However, the industrial production of GA is hindered by low yield and the accumulation of the intermediate product GlycyrrhetinicAcid3-O-Mono-ß-D-Glucuronide (GAMG). This study first identified a novel ß-glucuronidase (AcGUS) from Aspergillus calidoustus CLH-22 through transcriptomic analysis, demonstrating a substrate preference for GAMG. Subsequently, mutant AcGUS3G461C/Q462H/I575K with significantly improved activity (kcat/Km of 11.02-fold) was obtained via computer-aided engineering. Furthermore, the dual-GUS combination strategy was employed for the first timeto construct engineered Pichia pastoris for GA production, offering multiple advantages of enhanced conversion efficiency and reduced fermentation viscosity. Finally, under systematically optimized conditions and employing Glycyrrhizin (GL) as the substrate, the final concentration of GA was 48.73 g/L with a conversion of 97.26 % in a 1000-L fermenter, representing the optimal biocatalytic performance reported to date. This study provides new ideas and insights for industrial GA production.

Syngas production and gas-N evolution over heterogeneously doped La-Fe-O perovskite-type oxygen carriers in chemical looping gasification of microalgae.

Chemical looping gasification (CLG) is a promising technology for syngas production with low pollutant emission. In this study, doped La-Fe-O perovskites including LaFeO3 (LF), LaFe0.5Ni0.5O3 (LN5F5) and La0.3Ba0.7FeO3 (L3B7F) were developed for microalgae CLG. The as-prepared perovskites exhibited an outstanding performance in syngas production with accumulative syngas yield > 33 mol/kg. For gas-N evolution, perovskites were beneficial to the formation of NH3 and HCN, while the iron ore may convert precursors to NO. Below 400 °C, NOx can be stored on the perovskite surface in the form of nitrite/nitrate species. When the temperature was above 700 °C, NOx can be selectively reduced by reducing components in tar or syngas under the catalysis of L3B7F, resulting in the final reduction of NOx emission. Thus, CLG over L3B7F may be a promising way for efficient utilization of microalgae to overcome the intractable nitrogen-related obstacles in the commercial application of biomass gasification technologies.

Rapid Evaporation of a Metal Electrode for a High-Efficiency Perovskite Solar Cell.

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted considerable attention due to the excellent optoelectronic properties of perovskite materials. The energy consumption and high cost issues of metal electrode evaporation should be addressed before large-scale manufacturing and application. We developed an effective metal electrode evaporation procedure for the fabrication of high-efficiency planar heterojunction (PHJ) PSCs, with an inverted device structure of glass/indium tin oxide (ITO)/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA)/perovskite/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/(E)-ß-caryophyllene (BCP)/Ag. The effect of the evaporation rate for an evaporator with a small-volume metal cavity on the performance of PHJ-PSC devices was investigated systematically. Through controlling the processes of Ag electrode evaporation, the charge dynamics of the devices were studied by analyzing their charge recombination resistance and lifetime, as well as their defect state density. Our findings reveal that the evaporation rate of an evaporator with a small cavity is favorable for the performance of PHJ-PSCs. As a result, PHJ-PSCs fabricated using a very thin, non-doped PTAA film exhibit photoelectric conversion efficiency (PCE) of 19.21%, with an open-circuit voltage (Voc) of 1.132 V. This work showcases the great potential of rapidly evaporating metal electrodes to reduce fabrication costs, which can help to improve the competitiveness in the process of industrialization.