Construction of hydrogen fermentation from garbage slurry using the membrane free bioelectrochemical system

The aim of this study was to show the effectiveness of the membrane free bioelectrochemical system (BES) using three electrodes on inhibition of methanogenesis and construction of hydrogen fermentation from the artificial garbage slurry. The electrical redox-potential on the working electrode was adjusted to -1.0V (vs. Ag/AgCl) that has positive effect on methanogenesis. The redox-potential on the counter electrode was measured to be 1.6V. The pH in the effluents was 5.5-6.4. Hydrogen production rate at the cathode side was similar to that at the anode side and much higher than that calculated from current, and reached a maximum of 2445±815 (average±standard deviation) mL?L(-1)?d(-1) at an organic loading rate of 58.7g dichromate chemical oxygen demand per L d(-1). Methane production was negligible throughout the experiment. Acetate and butyrate were the main products of the fermentation using a BES; these offered favorable conditions for hydrogen production. The bacterial community in the bioelectrochemical hydrogen fermentor differed from that in the methanogenic seed sludge and included hitherto unknown species. These results show that high redox-potential on the anodic electrode and acidic pH in the membrane free BES can be utilized for hydrogen fermentation from the artificial garbage slurry by avoiding methanogenesis.     

Acceleration of cellulose degradation and shift of product via methanogenic co-culture of a cellulolytic bacterium with a hydrogenotrophic methanogen

Although the effects of syntrophic relationships between bacteria and methanogens have been reported in some environments, those on cellulose decomposition using cellulolytic bacteria from methanogenic reactors have not yet been examined. The effects of syntrophic co-culture on the decomposition of a cellulosic material were investigated in a co-culture of Clostridium clariflavum strain CL-1 and the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain ΔH and a single-culture of strain CL-1 under thermophilic conditions. In this study, strain CL-1 was newly isolated as a cellulolytic bacterium from a thermophilic methanogenic reactor used for degrading garbage slurry. The degradation efficiency and cell density of strain CL-1 were 2.9- and 2.7-fold higher in the co-culture than in the single-culture after 60?h of incubation, respectively. Acetate, lactate and ethanol were the primary products in both cultures, and the concentration of propionate was low. The content of acetate to total organic acids plus ethanol was 59.3% in the co-culture. However, the ratio decreased to 24.9% in the single-culture, although acetate was the primary product. Therefore, hydrogen scavenging by the hydrogenotrophic methanogen strain ΔH could shift the metabolic pathway to the acetate production pathway in the co-culture. Increases in the cell density and the consequent acceleration of cellulose degradation in the co-culture would be caused by increases in adenosine 5'-triphosphate (ATP) levels, as the acetate production pathway includes ATP generation. Syntrophic cellulose decomposition by the cellulolytic bacteria and hydrogenotrophic methanogens would be the dominant reaction in the thermophilic methanogenic reactor degrading cellulosic materials.     

Adhesion Properties of Acrylic Copolymers Modified with Si-Containing Copolymer

We made clear the cause of the increase in peel strength of pressure sensitive (PS) adhesives as a function of contact time, and investigated how to modify PS adhesives to maintain a low and constant peel strength for a long time. It was found that polar groups in the adhesive orient to the interface between the adhesive and the (stainless steel) metal substrate (SUS 304) so as to minimize interfacial free energy during adhesion, and the orientation increased affinity between the adhesive and the metal material and increased the peel strength as a result. The use of modifier which contained both P(MMA-co-SiMA) and PDMS showed an excellent modification effect, although modification with only PDMS or P(MMA-co-SiMA) was not sufficient. It was suggested that PDMS which migrated to the surface was extended uniformly over the surface by PDMS segments of P(MMA-co-SiMA) and that the enriched layer of PDMS on the adhesive surface worked as a barrier to prevent the orientation of polar groups in bulk. Therefore, low and constant peel strength could be achieved.     

A comparative numerical study of hybrid-stabilized argon–water electric arc

The paper presents numerical simulations of the discharge and the near-outlet regions of the hybrid-stabilized argon–water electric arc. Two different numerical methods for solving the set of conservative equations for the continuity, momentum and energy have been applied. The major difference between the results using the two methods occurs in the temperature distribution in arc fringes within the discharge chamber. This fact influences the potential drop, overpressure, reabsorption of radiation and arc efficiency. It is shown that the radial profiles of temperature at the exit nozzle are less influenced by different temperature distribution within the discharge chamber. Comparison with chosen experimental temperature profiles shows very good agreement.     

Changes in lipids in liver and serum of rats fed a histidine-excess diet or cholesterol-supplemented diets

The influence of dietary excess (5%) L-histidine on serum and liver lipids was examined in rats. Feeding a histidine-excess diet for 3, 6, 14 or 30 days caused growth retardation, hepatomegaly and decreased liver lipids throughout the period of the experiment. Hypercholesterolemia was observed after feeding a histidine-excess diet for 6 days; then serum cholesterol continuously increased for 30 days. Serum triglyceride on day 30 in rats fed the histidine-excess diet showed a significant decrease compared to rats fed the basal diet. Serum phospholipids of rats fed the histidine-excess diet for 7 or 14 days showed a significant increase compared to rats fed the basal diet. When rats were fed a basal, histidine-excess or cholesterol-supplemented diet (0.5% and 1.0% cholesterol) for 6 days, the distribution of serum high density (HDL), low density (LDL) and very low density lipoprotein cholesterol in rats fed the histidine-excess diet was similar to that of rats fed the basal diet, whereas LDL-cholesterol increased and HDL-cholesterol decreased in rats fed the cholesterol-supplemented diet.     

Analysis of the stability of mutant lysozymes at position 15 using X-ray crystallography

His 15 of hen lysozyme is located at the protein surface and is partly buried by the neighboring residues. The side chain of His 15 forms hydrogen bonds with surrounding residues and these hydrogen bonds are somewhat buried. A series of mutant lysozymes at the position 15 (Gly, Ala, Val, and Phe) was prepared, and their stabilities were analyzed by GdnHCl denaturation and X-ray crystallography. The mutants were less stable than the wild type at pH 5.5 and 35 degrees C. In H15G and H15A, X-ray crystallography revealed two fixed water molecules at the mutated region, which formed similar hydrogen bonds to those in the wild type. On the other hand, it was suggested that the hydrogen bonds were disrupted and that several unfavorable van der Waals' contacts occurred in H15V and H15F. Therefore, we concluded that His 15 stabilized the lysozyme structure by forming hydrogen bonds and the best packing with the neighboring residues. Moreover, we found that the method of protein stabilization by increasing the hydrophobicity of an amino acid residue was not always effectively applicable, especially when the residue had formed a hydrogen bond.     

Simple technique for pancreatogastrostomy and the histological findings of pancreatogastric anastomosis

The leakage of pancreatic juice is the most serious complication after pancreatoduodenectomy. In an attempt to lessen the incidence of this complication, we have developed a simple technique for the anastomosis of pancreatogastrostomy. Since March 14, 1995, we have already performed surgical procedures on 8 cases of pancreatogastrostomy using this technique and as yet have never experienced fatal complications. We report the autopsy findings of pancreatogastric anastomosis histologically. The specimen taken from the anastomosis reveals good mucosal continuity. This result suggests the importance of reliable sutures between the pancreatic parenchyma and the full thickness of the gastric wall for the anastomosis of pancreatogastrostomy.     

Flow dynamics in Taylor–Couette flow reactor with axial distribution of temperature

In this study, the flow dynamics of a Taylor–Couette flow with an axial distribution of temperature was experimentally investigated. The flow can be classified into three patterns based on the balance between the centrifugal force and the buoyancy. If the buoyancy is dominant, global heat convection is observed instead of Taylor vortices (Case I). When the buoyancy is comparable to the centrifugal force, the Taylor vortices and global heat convection appear alternately (Case II). If the centrifugal force is sufficiently high to suppress the buoyancy, stable Taylor vortices are observed (Case III). The characteristics of the mixing/diffusion are investigated by conducting a decolorization experiment on a passive tracer. In Case II, the tracer is rapidly decolorized in the presence of the global heat convection instead of the Taylor vortices. This result implies that the interaction between the centrifugal force and the buoyancy would induce an anomalous transport. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1075–1082, 2018     

Solubility of Nitrogen Gas in Aqueous Solution of Tetra-<Emphasis Type="Italic">n</Emphasis>-Butylammonium Bromide

Semiclathrate hydrates are water-based host-guest compounds formed from aqueous solutions of ionic guest substances. These materials can greatly moderate formation pressures and temperatures from canonical gas hydrates. This is a significant advantage for industrial applications such as gas separation and storage. \(\hbox {N}_{2}\) gas is a major component contained in various flue gases and is usually mixed with \(\hbox {CO}_{2}\). Semiclathrate hydrates can separate these gases under moderate thermodynamic conditions. Tetra-n-butylammonium bromide (TBAB) is a widely used ionic guest substance. To develop the application technologies and their theoretical models, solubility data of \(\hbox {N}_{2}\) gas in TBAB aqueous solutions are required. In this study, we report \(\hbox {N}_{2}\) gas solubility measured by an absolute gravimetric method for the semiclathrate hydrate formation system of \(\hbox {TBAB} + \hbox {H}_{2}\hbox {O} + \hbox {N}_{2}\). The measurement pressures, temperatures and TBAB mass fractions were 3 MPa, 5 MPa and 7 MPa, 292.15 K, 302.15 K and 307.15 K, and 0 (pure water), 0.10, 0.20, 0.32 and 0.40, respectively. The uncertainties were 0.056 MPa, 0.44 K and 0.00012 in mole fraction. Although the technical difficulty lays on measurements of small \(\hbox {N}_{2}\) gas solubility by the absolute gravimetric method, our data implied the unique gas dissolution property of aqueous TBAB solution depending on the TBAB concentration. The aqueous TBAB solutions with mass fractions of 0.10 and 0.20 had similar \(\hbox {N}_{2}\) gas solubility as that in pure water. With higher mass fractions, 0.32 and 0.40, the \(\hbox {N}_{2}\) gas solubility slightly increased from that in pure water, which implies the salting-in effect of TBAB.