Establishing and verifying of model for methane mass transfer in DAMO process

Denitrification anaerobic methane oxidation (DAMO) is a discovery in environmental science and engineering field. DAMO process releases a large of free energy, but DAMO microbial growth is extremely slow. The doubling time is as long as one month or more, which makes it difficult to attain DAMO enrichment culture. Methane is thought to be the key element on DAMO bacteria enrichment, because it is insoluble in water. A mathematical model describing methane behavior in gas-liquid-bacteria phases was set up to study the effect of methane on DAMO bacteria enrichment. Based on the model analysis, a relational expression between DAMO specific activity, methane partial pressure in gas phase and resistance of mass transfer was obtained, which was confirmed by DAMO specific activity test

Generation of vibration load spectrum for fatigue analysis of equipment mounted on bogie frame of railway vehicle based on fatigue damage spectrum

The equipment mounted on the bogie frame of railway vehicles is subjected to non-stationary vibrations from the bogie frame. Currently, the vibration load spectrum for fatigue analysis of equipment is expressed with the power spectral density, which is generally obtained with the power values of measured vibrations or stationary Gaussian vibrations collected at the specific operating conditions. However, this does not have the equivalent damage potential as the non-stationary vibrations. Thus, a generation method of the vibration load spectrum is proposed based on the fatigue damage spectrum (FDS) to obtain the equivalent damage potential as the one from the non-stationary vibrations in this paper. That is, the FDS of non-stationary vibration is calculated with the time domain method, and the vibration load spectrum is generated in the frequency domain with this FDS. Then the method is verified by the measured vibration and dynamic strain of equipment. Finally, the vibration load spectrum of equipment mounted on the bogie frame is generated with the measured vibrations in a maintenance cycle and the fatigue analysis is performed. The results show that the generated vibration load spectrum can validly contain the high power in non-stationary vibrations and express the distribution of power over frequency, which gives much better estimates of the fatigue damage of equipment than other load spectra. The generated vibration load spectrum is suitable for quantifying the actual non-stationary vibrations and can be used for the anti-fatigue design of equipment

Microbiological and environmental significance of metal-dependent anaerobic oxidation of methane

Highlights • The process of prediction and discovery of metal-AOM is reviewed. • Responsible microorganisms and mechanisms of metal-AOM are identified. • Environmental significance of methane cycle and geochemistry is presented. • Effects of environmental factors and metal forms on metal-AOM are discussed. Abstract Anaerobic oxidation of methane (AOM) can be coupled to the reduction of sulfate, nitrate and nitrite, which effectively reduces methane emission into the atmosphere. Recently, metal-dependent AOM (metal-AOM, AOM coupled to metal reduction) was demonstrated to occur in both environmental samples and enrichment cultures. Anaerobic methanotrophs are capable of respiration using Fe(III) or Mn(IV), whether they are in the form of soluble metal species or insoluble minerals. Given the wide distribution of Fe(III)/Mn(IV)-bearing minerals in aquatic methane-rich environments, metal-AOM is considered to be globally important, although it has generally been overlooked in previous studies. In this article, we discuss the discovery of this process, the microorganisms and mechanisms involved, environmental significance and factors influencing metal-AOM. Since metal-AOM is poorly studied to date, some discussion is included on the present understanding of sulfate- and nitrate-AOM and traditional metal reduction processes using organic substrates or hydrogen as electron donors. Metal-AOM is a relatively new research field, and therefore more studies are needed to fully characterize the process. This review summarizes current studies and discusses the many unanswered questions, which should be useful for future research in this field

Mdodeling a nitrite-dependent anaerobic methane oxidation process: parameters identification and model evaluation

Nitrite-dependent anaerobic methane oxidation (n-damo) is a recently discovered process that is intermediated by n-damo bacteria that oxidize methane with nitrite to generate nitrogen gas. In this work, a kinetic model based on Monod type kinetics and diffusion-reaction model was developed to describe the bioprocess. Some key kinetic parameters needed in the model were obtained from a series of batch activity tests and a sequencing batch reactor (SBR) operation over 100days. The growth rate, decay rate, methane affinity constant, nitrite affinity constant and inhibition constant were 0.0277±0.0022d, 0.00216±0.00010d, 0.092±0.005mmolL, 0.91±0.09mmolL and 4.1±0.5mmolL for n-damo bacteria at 30°C, respectively. The results showed that the model could simulate actual performance of the SBR in the first 76days, that methane was not a limiting factor at atmospheric pressure for its high affinity, and that the optimum nitrite concentration was 1.92mmolL

Cultivation of nitrite-dependent anaerobic methane-oxidizing bacteria: impact of reactor configuration

Nitrite-dependent anaerobic methane oxidation (n-damo) is mediated by bacteria that anaerobically oxidize methane coupled with nitrite reduction and is a potential bioprocess for wastewater treatment. In this work, the effect of reactor configuration on n-damo bacterial cultivation was investigated. A magnetically stirred gas lift reactor (MSGLR), a sequencing batch reactor (SBR), and a continuously stirred tank reactor (CSTR) were selected to cultivate the bacteria. Microbial community was monitored by using quantitative PCR, 16S rRNA gene sequencing, pmoA gene sequencing, and fluorescence in situ hybridization (FISH). The effects of substrate inhibition, methane mass transfer, and biomass washout in the three reactors were focused on. The results indicated that the MSGLR had the best performance among the three reactor systems, with the highest total and specific n-damo activities. Its maximum volumetric nitrogen removal rate was up to 76.9 mg N L day, which was higher than previously reported values (5.1-37.8 mg N L d)

Applied Research Note: Development and validation of a highly specific polyclonal antibody targeting neuraminidase of novel H3N8 avian influenza virus

SUMMARY: Avian influenza viruses (AIV) of the H3N8 subtype pose a significant threat to both the poultry industry and public health. This study aimed to develop and validate a highly specific polyclonal antibody targeting the neuraminidase (NA) protein from a novel H3N8 AIV, which exhibits tri-basic hemagglutinin cleavage sites and shares genetic proximity to recent human isolates. The NA gene of H3N8 AIV was cloned and introduced into E. coli BL21 and Rosetta competent cells to induce the recombinant protein expression. Optimization procedures, including IPTG concentration, time, and temperature, were implemented to enhance protein expression efficiency. Polyclonal antibodies were generated and validated through western blotting, indirect immunofluorescence assay (IFA), and indirect ELISA. As a result, the pET-32a-NA (N8) vector was successfully constructed. The expression of recombinant NA protein with a size of approximately 70 KDa was obtained and then optimized with a final IPTG concentration of 0.6 mM, at 27°C for 14 h. Western blotting and IFA analysis demonstrated that the prepared polyclonal antibody effectively and specifically bound to NA(N8) protein. The titer of the polyclonal antibodies reached 1:409600 by indirect ELISA. These results indicate the potential of these antibodies for the development of detection assays and biological studies required for H3N8 AIVs

Management of patient with Fusobacterim nucletum related pleural empyema: intrapleural antibiotic therapy can be considered for salvage therapy

Abstract Pleural empyema can lead to significant morbidity and mortality despite chest drainage and antibiotic treatment, necessitating novel and minimally invasive interventions. Fusobacterium nucleatum is an obligate anaerobe found in the human oral and gut microbiota. Advances in sequencing and puncture techniques have made it common to detect anaerobic bacteria in empyema cases. In this report, we describe the case of a 65-year-old man with hypertension who presented with a left-sided encapsulated pleural effusion. Initial fluid analysis using metagenomic next-generation sequencing (mNGS) revealed the presence of Fusobacterium nucleatum and Aspergillus chevalieri. Unfortunately, the patient experienced worsening pleural effusion despite drainage and antimicrobial therapy. Ultimately, successful treatment was achieved through intrapleural metronidazole therapy in conjunction with systemic antibiotics. The present case showed that intrapleural antibiotic therapy is a promising measure for pleural empyema