Biogas Production Potential and Kinetics of Microwave and Conventional Thermal Pretreatment of Grass

Pretreatment methods play an important role in the improvement of biogas production from the anaerobic digestion of energy grass. In this study, conventional thermal and microwave methods were performed on raw material, namely, Pennisetum hybrid, to analyze the effect of pretreatment on anaerobic digestion by the calculation of performance parameters using Logistic function, modified Gompertz equation, and transference function. Results indicated that thermal pretreatment improved the biogas production of Pennisetum hybrid, whereas microwave method had an adverse effect on the performance. All the models fit the experimental data with R-2&gt;0.980, and the Reaction Curve presented the best agreement in the fitting process. Conventional thermal pretreatment showed an increasing effect on maximum production rate and total methane produced, with an improvement of around 7% and 8%, respectively. With regard to microwave pretreatment, maximum production rate and total methane produced decreased by 18% and 12%, respectively.</p

Approximate Series Solutions for Nonlinear Free Vibration of Suspended Cables

This paper presents approximate series solutions for nonlinear free vibration of suspended cables via the Lindstedt-Poincare method and homotopy analysis method, respectively. Firstly, taking into account the geometric nonlinearity of the suspended cable as well as the quasi-static assumption, a mathematical model is presented. Secondly, two analytical methods are introduced to obtain the approximate series solutions in the case of nonlinear free vibration. Moreover, small and large sag-to-span ratios and initial conditions are chosen to study the nonlinear dynamic responses by these two analytical methods. The numerical results indicate that frequency amplitude relationships obtained with different analytical approaches exhibit some quantitative and qualitative differences in the cases of motions, mode shapes, and particular sag-to-span ratios. Finally, a detailed comparison of the differences in the displacement fields and cable axial total tensions is made

Genetic etiological analysis of auditory neuropathy spectrum disorder by next-generation sequencing

ObjectiveAuditory neuropathy spectrum disease (ANSD) is caused by both environmental and genetic causes and is defined by a failure in peripheral auditory neural transmission but normal outer hair cells function. To date, 13 genes identified as potentially causing ANSD have been documented. To study the etiology of ANSD, we collected 9 probands with ANSD diagnosed in the clinic and performed targeted next-generation sequencing.MethodsNine probands have been identified as ANSD based on the results of the ABR tests and DPOAE/CMs. Genomic DNA extracted from their peripheral blood was examined by next-generation sequencing (NGS) for a gene panel to identify any potential causal variations. For candidate pathogenic genes, we performed co-segregation among all family members of the pedigrees. Subsequently, using a mini-gene assay, we examined the function of a novel splice site mutant of OTOF.ResultsWe analyzed nine cases of patients with ANSD with normal CMs/DPOAE and abnormal ABR, discovered three novel mutants of the OTOF gene that are known to cause ANSD, and six cases of other gene mutations including TBC1D24, LARS2, TIMM8A, MITF, and WFS1.ConclusionOur results extend the mutation spectrum of the OTOF gene and indicate that the genetic etiology of ANSD may be related to gene mutations of TBC1D24, LARS2, TIMM8A, MITF, and WFS1

Anthropogenic influence on 2018 summer persistent heavy and daily extreme rainfall in central western China

Anthropogenic forcing has reduced the probability of summer persistent heavy rainfall in central western China similar to 2018 by ~47%, but increased that of daily extremes by ~1.5 times, based on HadGEM3-GA6 ensembles

Improving methane production from Pennisetum hybrid by monitoring plant height and ensiling pretreatment

The biomass of grass-based Pennisetum hybrid commonly use for a biogas production via anaerobic digestion. However, it is necessary to determine a method to optimize the plant harvest time for high biogas production. Moreover, ensiling of biomass in the presence of diverse microbes may offer a solution to improve biogas production. In this study, whole plant of Pennisetum biomass (including stems and leaves) was collected at different harvesting time (plant heights of 70, 100, 150 cm), and then comparatively assessed for further ensiling and biogas production. Compared to leaves, stems exhibited a significant linear relationship (R2 = 0.99) with whole plants in terms of ensiling quality (i.e. pH and NH3-N). Microbial analysis further revealed that Lactobacillus was the dominant bacterial genus during ensiling of stems and whole plants, with the highest relative abundance of 50.08% obtained at the height of 100 cm. Ensiling of biomass at a height of 100 cm achieved the best digestion performance, with the methane yields of 316 ± 20 mL/g VS for leaves, 361 ± 43 mL/g VS for stems, and 356 ± 28 mL/g VS for whole plants. A harvesting time at the plant height of 100 cm was the optimal from the silage quality and anaerobic digestion performance

Bioaugmentation strategy for enhancing anaerobic digestion of high C/N ratio feedstock with methanogenic enrichment culture

To investigate whether bioaugmentation could improve the digestion performance of high C/N ratio feedstock without co-digestion with nitrogen-rich substrate, different forms of enriched methanogenic culture were introduced to the continuous feed digesters. The performance efficiency of bioaugmentation on digestion improvement was compared. The effect of bioaugmentation on microbial community composition was revealed as well. Results demonstrated that routine bioaugmentation with liquid culture (containing the microbes and the medium remains) showed the best performance, with the organic loading rate (OLR), methane percentage, volumetric methane production (VMP) and volatile solid methane production (VSMP) higher at 1.0 g L-1 d(-1), 24%, 0.22 L L-1 d(-1) and 0.23 L g(-1) VS d(-1) respectively, compared to the non-bioaugmentation control. Whole genome pyrosequencing analysis suggested that consecutive microbial consortium addition could reconstruct the methanogens community by increasing the populations of acetoclastic methanogens Methanothrix, which could accelerate the degradation of acetate and methane production

Bioaugmentation for overloaded anaerobic digestion recovery with acid-tolerant methanogenic enrichment

This study aims to investigate the performance of bioaugmentation with an acid-tolerant methanogenic culture to recover deteriorated anaerobic digestion caused by organic overloading. The function of bioaugmentation was evaluated in terms of substance metabolism, microbial community structure, and gene function. Our findings demonstrate that routine bioaugmentation effectively recovered the failing digester by degrading accumulated volatile fatty acids and increasing pH. In contrast, a non-bioaugmentation reactor (control) did not recover by itself, while abiotic augmentation restored the digestion performance temporarily but the digester failed again at an organic loading rate of 1.5 g L-1 d(-1). Using whole genome pyrosequencing analysis, we found that after bioaugmentation, the populations of Methanothrix (acetoclastic methanogens) and Methanolinea (hydrogenotrophic methanogens) increased significantly, which may be the main contributors for the positive effect on methane production. On the genic level, bioaugmentation may enhance the function of genes involved in cell motility, signal transduction mechanisms for methanogens, and energy production and conversion for bacteria. (C) 2018 Elsevier Ltd. All rights reserved

Approximate Series Solutions for Nonlinear Free Vibration of Suspended Cables

This paper presents approximate series solutions for nonlinear free vibration of suspended cables via the Lindstedt-Poincare method and homotopy analysis method, respectively. Firstly, taking into account the geometric nonlinearity of the suspended cable as well as the quasi-static assumption, a mathematical model is presented. Secondly, two analytical methods are introduced to obtain the approximate series solutions in the case of nonlinear free vibration. Moreover, small and large sag-to-span ratios and initial conditions are chosen to study the nonlinear dynamic responses by these two analytical methods. The numerical results indicate that frequency amplitude relationships obtained with different analytical approaches exhibit some quantitative and qualitative differences in the cases of motions, mode shapes, and particular sag-to-span ratios. Finally, a detailed comparison of the differences in the displacement fields and cable axial total tensions is made