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Meng, Fei

Publications and source records attributed to Meng, Fei.

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

A triton X-100 assisted PMAxx-qPCR assay for rapid assessment of infectious African swine fever virus

Introduction African Swine Fever (ASF) is a highly infectious disease of pigs, caused by African swine fever virus (ASFV). The lack of vaccines and drugs makes strict disinfection practices to be one of the main measurements to curb the transmission of ASF. Therefore, it is important to assess if all viruses are inactivated after disinfection or after long time exposure in their natural conditions. Currently, the infectivity of ASFV is determined by virus isolation and culture in a biosafety level 3 (BSL-3) laboratory. However, BSL-3 laboratories are not readily available, need skilled expertise and may be time consuming. Methods In this study, a Triton X-100 assisted PMAxx-qPCR method was developed for rapid assessment of infectious ASFV in samples. PMAxx, an improved version of propidium monoazide (PMA), can covalently cross-link with naked ASFV-DNA or DNA inside inactivated ASFV virions under assistance of 0.1% (v/v) TritonX-100, but not with ASFV-DNA inside live virions. Formation of PMAxx-DNA conjugates prevents PCR amplification, leaving only infectious virions to be detected. Under optimum conditions, the limit of detection of the PMAxx-qPCR assay was 2.32log 10 HAD 50 /mL of infectious ASFV. Testing different samples showed that the PMAxx-qPCR assay was effective to evaluate intact ASFV virions after treatment by heat or chemical disinfectants and in simulated samples such as swine tissue homogenate, swine saliva swabs, and environmental swabs. However, whole-blood and saliva need to be diluted before testing because they may inhibit the PCR reaction or the cross-linking of PMAxx with DNA. Conclusion The Triton X-100 assisted PMAxx-qPCR assay took less than 3 h from sample to result, offering an easier and faster way for assessing infectious ASFV in samples from places like pig farms and pork markets.

Liu, Huan↗
DOE OSTI2018

CtBP represses Dpp signaling as a dimer

Highlights: • Ectopic expression of CtBP causes a disrupted wing vein pattern. • CtBP causes a decreased pMad level. • CtBP requires dimerization to repress Dpp signaling pathway. C-terminal binding protein (CtBP) is a highly conserved transcriptional co-repressor in animal development and human diseases. In Drosophila, CtBP is critical for fly development and is thought to exert its repressive roles in many signaling pathways including Dpp/BMP pathway. Here we provide evidence that although wild type CtBP negatively and dominantly influences Dpp signaling in fly presumptive wings, mutant CtBP unable to form dimer does not, indicating that dimerization is required for the repression role of CtBP in Dpp signaling in vivo.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate

Olivine lithium iron phosphate is a technologically important electrode material for lithium-ion batteries and a model system for studying electrochemically driven phase transformations. Despite extensive studies, many aspects of the phase transformation and lithium transport in this material are still not well understood. Here we combine operando hard X-ray spectroscopic imaging and phase-field modeling to elucidate the delithiation dynamics of single-crystal lithium iron phosphate microrods with long-axis along the [010] direction. Lithium diffusivity is found to be two-dimensional in microsized particles containing ~3%lithium-iron anti-site defects. Our study provides direct evidence for the previously predicted surface reaction-limited phase-boundary migration mechanism and the potential operation of a hybrid mode of phase growth, in which phase-boundary movement is controlled by surface reaction or lithium diffusion in different crystallographic directions. These findings uncover the rich phase-transformation behaviors in lithium iron phosphate and intercalation com-pounds in general and can help guide the design of better electrodes.

25 ENERGY STORAGE↗
DOE OSTI2016

Highly Efficient Non-Oxidative Methane Conversion with Continuous Hydrogen Removal

A non-oxidative methane conversion catalytic system has been successfully developed. Ball-milling and annealing above 1973 K are necessary in order to synthesize the unique methane activation catalyst. Characterization and evaluation of catalysts shows that the surface area should be carefully controlled to minimize coke deposition. The influence of temperature, pressure, space velocity and hydrogen concentration on catalytic process was systematically studied. The reaction conditions were optimized to a combination of 1323 K, ambient pressure and a space velocity of 4900 ml/g·h. A process, using 0.5% Fe/SiO 2 catalyst under these conditions, yield a methane conversion of 15.62%, with product distribution of 40.05% C 2 , 26.48% BTX and 10.7% naphthalene and demonstrated stable operation of at least 50 hours. This result meets the milestone in the phase I proposal. A non-oxidative methane catalyst-integrated SOFC reactor was accomplished, using nickel-free cells of both ScSZ oxygen-ion conductor and BZY proton conductor. With in-situ hydrogen removal enabled by SOFC, hydrogen concentration in the reactor was effectively reduced, shifting reaction equilibrium and boosting methane conversion. However, due to the high temperature requirement of this reaction, most available proton-conducting SOFCs become oxygen-ion conducting, leading to side reactions and counteracting the benefits from hydrogen removal. To take advantage of the enhanced oxygen-ion conductance of SOFC at high temperatures, we have also paired the nickel-free SOFCs with high-performance oxidative coupling of methane (OCM) catalysts. The SOFC-OCM tubular membrane reactor, employing a Mn-Ce-Na 2 WO 4 /SiO 2 -based catalyst, demonstrates a remarkable performance of 60.7% methane conversion with 41.6% C 2 + selectivity, 5.8 ethylene-to-ethane ratio and 19.4% ethylene yield. The use of integrated SOFC-OCM reactor enables better hydrocarbon selectivity and higher ethylene-to-ethane ratio, eliminating the need of an expensive air separation unit and preventing the direct co-feed of explosive methane-oxygen mixture. We believe this presents a great promise towards commercialization as an advanced methane conversion technology.

02 PETROLEUM↗