Effect of food to microorganisms (F/M) ratio on biohythane production via single-stage dark fermentation

Hythane is a mixture of hydrogen and methane gases which are generally produced in separate ways. This work studied mesophilic biohythane gas (H₂+CH₄+CO₂) production in a bioreactor via single-stage dark fermentation. The fermentation was conducted in batch mode using mixed anaerobic microflora and food waste and condensed molasses fermentation soluble to elucidate the effects of food to microorganisms (F/M) ratio (ranging from 0.2 to 38.2) on gas production, metabolite variation, kinetics and biohythane-composition indicator performances. The experimental results indicate that the F/M ratio and fermentation time affect biohythane production efficiency with values of peak maximum hydrogen production rate 9.60 L/L-d, maximum methane production rate 0.72 L/L-d, and hydrogen yield (HY) of 6.17 mol H₂/kg COD_added. Depending on the F/M ratios, the H₂, CH₄ and CO₂ biogas components were 10–60%, 5–20% and 35–70%, respectively. Prospects for the further real application for single-stage biohythane fermentation based on the experimental data are proposed. This work characterizes an important reactor operation factor F/M ratio for innovative single-stage dark fermentation.     

Performance and population analysis of hydrogen production from sugarcane juice by non-sterile continuous stirred tank reactor augmented with Clostridium butyricum

Non-sterile operation of continuous stirred tank reactor (CSTR) augmented with Clostridium butyricum and fed with sugarcane juice was studied at various hydraulic retention time (HRT). The maximum hydrogen production rate and yield of 3.38 mmol H₂/L/h and 1.0 mol H₂/mol hexose consumed, respectively, were achieved at HRT 4 h. The relationship of the augmented microorganism and normal flora in the fermentation system under non-sterile condition were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Initially, at HRT 36 h, other species related to Lactobacillus harbinensis and Klebseilla pneumoniae were present as a major group in the reactor. When HRT was decreased to 12, 6 and 4 h, C. butyricum was present with a competition between L. harbinensis and K. pneumoniae. Results indicated that augmented C. butyricum could compete with contaminated microorganisms during non-sterile operation at low HRT (12-4 h) with the support of normal flora (K. pneumoniae).     

Investigation of the mouse cerebellum using STIM and μ-PIXE spectrometric and FTIR spectroscopic mapping and imaging

The cerebral biochemistry associated with the development of many neurological diseases remains poorly understood. In particular, incomplete understanding of the mechanisms through which vascular inflammation manifests in tissue damage and altered brain function is a significant hindrance to the development of improved patient therapies. To this extent, a combination of spectrometric/spectroscopic mapping/imaging methods with an inherent ability to provide a wealth of biochemical and physical information have been investigated to understand further the pathogenesis of brain disease.In this study, proton-induced X-ray emission (PIXE) mapping was combined with scanning transmission ion microscopy (STIM) mapping and Fourier-transform infrared (FTIR) imaging of the same tissue sample to study directly the composition of the murine (mouse) cerebellum. The combination of the elemental, density and molecular information provided by these techniques enabled differentiation between four specific tissue types within the murine cerebellum (grey matter, white matter, molecular layer and micro blood vessels). The results presented are complementary, multi-technique measurements of the same tissue sample. They show elemental, density and molecular differences among the different tissue types.     

The Metallic Nature of Epitaxial Silicene Monolayers on Ag(111)

Silicene is a two‐dimensional structure composed of a buckled hexagonal honeycomb lattice of silicon atoms. Freestanding silicene is yet to be synthesized, but epitaxial silicene monolayers have been directly observed or predicted to exist on a number of supporting substrates. Herein the atomic and electronic structures of five distinct epitaxial silicene morphologies on Ag(111) are examined through the complementary techniques of density functional theory and soft X‐ray spectroscopy at the Si L_2,3 edge. Hybridization with the Ag(111) substrate is shown to cause these silicene monolayers to become strongly metallic, and the specific electronic interactions that are responsible for this metallic nature are determined. The results imply that epitaxial silicene on Ag(111) does not possess the Dirac cone electronic structure that is characteristic of freestanding silicene and graphene sheets.