The use of a silicone-based biomembrane for microaerobic H2S removal from biogas

A lab-scale bio-membrane unit was developed to improve H2S removal from biogas through microaeration. Biomembrane separated biogas from air and consisted of a silicone tube covered by microaerobic biofilm. This setup allowed efficient H2S removal while minimizing biogas contamination with oxygen and nitrogen. The transport and removal of H2S, N-2, O-2, CH4 and CO2 through bare membrane, wet membrane and biomembrane was investigated. Membrane allowed the transfer of gases through it as long as there was enough driving force to induce it. H2S concentration in biogas decreased much faster with the biomembrane. The permeation of gases through the membranes decreased in order: H2S > CO2 > CH4 > O-2 > N-2. H2S removal efficiency of more than 99% was observed during the continuous experiment. Light yellow deposits on the membrane indicated the possible elemental sulfur formation due to biological oxidation of H2S. Thiobacillus thioparus was detected by FISH and PCR-DGGE

How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?

Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies

Absorption Spectroscopy in Dental Tissue Analysis

Oral health problems are closely associated with the analysis of dental tissue changes and the stomatologic treatment that follows. This paper explores the use of diffuse reflectance spectroscopy in the detection of dental tissue disorders. The data set includes 343 measurements of teeth spectra in the wavelength range from 400 to 1700 nm. The proposed methodology focuses on computational and statistical methods and the use of these methods for the classification of dental tissue into two classes (healthy and unhealthy) by estimating the probability of class membership. Signal processing is based on the difference between the healthy and unhealthy teeth reflectance spectra in the infrared and visible ranges. Selected features associated with observed spectra are then used for machine learning classification based on the experience of an expert in stomatology during the learning stage. The proposed modification of the weighted ${k}$ -nearest neighbour method provides class boundaries and the probability of class membership during the verification stage. The accuracy of the classification process reached 95.4%. The proposed methodology and graphical user interface point to the possibility of using absorption spectroscopy in the evaluation of tissue quality changes and its possible implementation in the clinical environment

Microaeration through a biomembrane for biogas desulfurization : lab-scale and pilot-scale experiences

Microaeration, a biological method to remove H2S from biogas by oxidizing it to elemental sulfur, has been shown to be highly efficient, simple and reliable. However, dosing air directly into an anaerobic fermenter results in the dilution of biogas with nitrogen and oxygen and can cause clogging of biogas pipes by elemental sulfur. These disadvantages can be overcome by the use of a biomembrane, i.e. a membrane covered with a biofilm that separates air and biogas. Experiments with bare, wet and biofilm membranes were conducted with a commercially available PVDF LM-P2 membrane to evaluate the chemical and biological oxidation rates of H2S. Different amounts of air were dosed through the biomembrane to determine the optimum air-to-biogas ratio, to evaluate methane losses and to evaluate biogas contamination with nitrogen and oxygen. The H2S content decreased from 3000 ppm to less than 100 ppm within two days. The loss of methane was 3.7% of the total methane production and the specific H2S removal rate was 32 mg m(-2) d(-1)