Production of porous suspension polymer beads with a narrow size distribution using a cross-flow membrane and a continuous tubular reactor

The work described focuses on a two-stage process for the production of large porous suspension polymer beads of defined particle size and narrow size distribution. Emulsification has been performed using purpose built cross-flow membrane equipment, which allows controlled production of large emulsion droplets with a much narrower size distribution. The work described compares the production of large emulsion droplets of monomer prepared both by agitation and using a cross-flow membrane. The effects of variations in the pore size of the membrane and flow-rates on the size of the emulsion droplets produced are also investigated. The second stage of the process is polymerisation of performed monomer emulsion droplets using a continuous tubular reactor. Samples polymerised using such a method show a narrower size distribution than similar systems polymerised as a batch.     

Entropy production of a mechanically driven single oligomeric enzyme: a consequence of fluctuation theorem

In this work we have shown how an applied mechanical force affects an oligomeric enzyme kinetics in a chemiostatic condition where the statistical characteristics of random walk of the substrate molecules over a finite number of active sites of the enzyme plays important contributing factors in governing the overall rate and nonequilibrium thermodynamic properties. The analytical results are supported by the simulation of single trajectory based approach of entropy production using Gillespie’s stochastic algorithm. This microscopic numerical approach not only gives the macroscopic entropy production from the mean of the distribution of entropy production which depends on the force but also a broadening of the distribution by the applied mechanical force, a kind of power broadening. In the nonequilibrium steady state (NESS), both the mean and the variance of the distribution increases and then saturates with the rise in applied force corresponding to the situation when the net rate of product formation reaches a limiting value with an activationless transition. The effect of the system-size and force on the entropy production distribution is shown to be constrained by the detailed fluctuation theorem.     

Hydrogenation of Dicyclopentadiene in the Presence of a Nickel Catalyst Supported onto a Cation Exchanger in a Flow-Type Reactor

The process of dicyclopentadiene hydrogenation in the gas–liquid–solid catalyst system with a catalyst of nickel nanoparticles supported onto a Purolite CT-175 cation exchange resin was studied. The surface structure of the catalyst and the kinetics of the dicyclopentadiene hydrogenation process were examined. Optimum conditions were found for the production of endo-tetrahydrodicyclopentadiene and the simultaneous production of endo-tetrahydrodicyclopentadiene and 5,6-dihydrodicyclopentadiene at atmospheric pressure.     

Advantages of synthesizing trans-1,2-cyclohexanediol in a continuous flow microreactor over a standard glass apparatus

Comparison is made between the preparation of trans-1,2-cyclohexanediol in standard glassware (conventional batch production) and in a microreactor (continuous flow production). The reaction sequence involved two exothermic steps where the standard procedure demands slow reagent addition and careful temperature control. In the microreactor, the reaction could be carried out safely with up to 3 times higher reagent concentration. Synthetic benefits were a faster reaction rate and a higher purity product free of colored impurities (a feature of the batch procedure).     

Lipase production byPenicillium restrictum in a bench-scale fermenter

A preliminary screening work selectedPenicillium restrictum as a promising micro-organism for lipase production. The physiological response of the fungus towards cell growth and enzyme production upon variable carbon and nitrogen nutrition, specific air flow rate (Qa) and agitation (N) was evaluated in a 5-L bench-scale fermenter. In optimized conditions for lipase production meat peptone at 2% (w/v) and olive oil at 1% (w/v) were used in a growth medium with a C/N ratio of 9.9. Higher C/N ratios favored cell growth in detriment of enzyme production. Low extracellular lipase activities were observed using glucose as carbon source suggesting glucose regulation. Final lipase accumulation of 13,000 U/L was obtained, using optimized specific air flow rate (Qa) of 0.5 wm and an impeller speed (N) of 200 rpm. Agitation showed to be an important parameter to ensure nutrient availability in a growth medium having olive oil as carbon source.     

Le vaporeformage catalytique : application a la production embarquee d'hydrogene a partir d'hydrocarbures ou d'alcools

Catalytic steam reforming : Use for on-board hydrogen production from hydrocarbons or alcohols. To identify the challenges in the development of electrical vehicles, literature was rapidly reviewed. Research on hydrogen production processes suitable for fuel cell applications is a major challenge. Catalytic steam reforming of hydrocarbons as well as alcohol is a very promising route. The choice of ethanol and supported rhodium catalysts will be justified in the light of ethanol physico-chemical properties, reaction mechanism, cerium-based oxides characteristics and the specifications imposed by fuel cell applications.     

Oxygen limitation on L-serine production in a hollow-fiber bioreactor

Pseudomonas AM1 utilizes glycine and methanol to producel-serine aerobically(1). The consumption of methanol in this bioconversion is stoichiometrically in excess of L-serine production(2). Consequently, the oxygen requirement associated with L-serine production is higher than expected for the conversion from glycine. One method of L-serine production investigated was a technique utilizing a hollow-fiber ultrafiltration cartridge as a bioreactor. Oxygen diffusion limitations appear to impede the consumption of methanol and, consequently, the production of L-serine in such a reactor. Methanol consumption data agree with predictions based on a hollow-fiber diffusion model.     

Investigation of a deoxyribozyme as a biofuel cell catalyst

We examined the ability of a previously identified peroxidase deoxyribozyme to be employed as a catalyst in biofuel cells, as a possible replacement for oxidoreductase proteins. We constructed a biocathode using a covalently linked version of the peroxidase deoxyribozyme-hemin complex and successfully paired it with a glucose dehydrogenase-modified bioanode for power production.     

亚心形四爿藻培养和产氢过程一体化平板光生物反应系统

利用整合了燃料电池的平板光生物反应器, 探讨了将亚心型四爿藻高密度培养和产氢两段工艺一体化集成的可行性. 在培养阶段通入体积分数为2%~5%的CO2可使藻细胞迅速增殖, 9 d内即可达到产氢要求的生物量(8.5×106 cell/mL). 通过叶绿素荧光参数分析, 选择2%的CO2培养的藻进行后续的产氢实验. 结果表明, PSⅡ活性和光合电子传递速率均随时间的推移而逐渐下降. 通过对产氢动力学曲线的分析, 计算出最大产氢速率为1.1 mL/(h·L), 持续产氢时间为60 h.     

Evaluating a time-delay of hydrogen production quantitatively in photosynthetic bacteria for stabilizing intermittency

Renewable energy is regarded as a clean energy source but has some problems, one of which is intermittency. To reduce this, the time-delay of hydrogen production by photosynthetic bacteria can be effective. In this study, we qualitatively evaluated the time-delay of hydrogen production by photosynthetic bacteria under various irradiation conditions, and we also quantitatively evaluated it by fitting the experimental data and the hydrogen production model with a genetic algorithm. As a result of model fitting, we found that the relationship between the lengths of the optimized time-delay of hydrogen production by photosynthetic bacteria and the amount of light irradiation is linear. And we also found that the time-delay of hydrogen production by photosynthetic bacteria had an upper limit under low light intensity. We have suggested the existence of an energy store mechanism in photosynthetic bacteria.     

Optimization of the biological component of a bioelectrochemical cell

The efficiency of electron transduction by Shewanella oneidensis MR-1 was investigated both in batch culture and in a dual-chambered electrochemical cell. Aerobically grown bacteria were inoculated into an insoluble FeOOH suspension in an anaerobic environment. As the bacteria reduced Fe(III) to Fe(II) there was a visible color change from red to bluish black; this simple color change assay proved to be a robust method for determining the electrochemical activity of S. oneidensis MR-1. In an effort to improve electricity production by S. oneidensis MR-1, the performance of the electrochemical cell with lactate as a fuel was first optimized with respect to both poised potential and fuel concentration. Ultimately, electricity production proved to be proportional to both the poised potential and to fuel concentration. In particular, higher poised potentials increased charge production. Finally, we attempted to optimize the bacteria themselves for the efficient transduction of reduced carbon sources into electricity. The batch culture underwent a series of serial dilutions; after the 4th dilution the microbe population exhibited a 30% increase in charge production. We are further exploring whether this increase was due to metabolic adaptations or to genetic mutations, and examining additional ways to evolve electrogenic organisms.     

Immobilized cells of a unicellular green alga and a photosynthetic bacterium for use in a biophotolysis system

Applied Biochemistry and Biotechnology - Immobilization of algal and bacterial cells was investigated, and found applicable to our hydrogen production system. Both a unicellular green alga,...     

Fluctuation theorem for entropy production in a chemical reaction channel

Fluctuation theorem for entropy production in a mesoscopic chemical reaction network is discussed. When the system size is sufficiently large, it is found that, by defining a kind of coarse-grained dissipation function, the entropy production in a reversible reaction channel can be approximately described by a type of detailed fluctuation theorem. Such a fluctuation relation has been successfully tested by direct simulations in a linear reaction model consisting of two reversible channels and in an oscillat...     

The Sherman equations as a nonlinear Perron eigenvalue problem

When a chemical sample composed of N elements is analyzed using sequential selective excitation by a tunable polyenergetic X-ray beam and selective measurement of the characteristic X-rays, the production of secondary fluorescence does not interfere with the measurements. This experimental situation leads to a particular case of the Sherman equations which can be written as a set of non-linear equations. The same kind of equations are also obtained when we excite a chemical sample with a polyenergetic X-ray beam and neglect the production of secondary fluorescence. This set of equations can be regarded as a non-linear eigenvalue problem. A non-linear extension of the Perron Frobenious theorem ensures that there is one and only one physically acceptable solution, and also leads to a method to obtaining it. The propagation off measurements errors of sample fluorescence to errors in the calculated sample concentrations, has been simulated, and the results show that the solution is well conditioned. The case of production of secondary fluorescence can not be treated, in general, as a nonlinear Perron eigenvalue problem, but it has been shown that it is rather plausible that Sherman equations corresponding to the actual chemical elements and that include the production of secondary fluorescence have one and only one physically acceptable solution. An exhaustive search could elucitate the existence and unicity of solutions for the equations corresponding to the actual chemical elements.     

Titanium production in a plasma reactor: A feasibility investigation

The feasibility of producing titanium metal from titanium tetrachloride in a thermal plasma under equilibrium and adiabatic expansion conditions has been theoretically investigated. Free energy minimization and adiabatic expansion calculations to simulate a nozzle expansion were used to study the practicality of production. The crucial requirements for the production of titanium powder from TiCl₄ and H₂ appear to be rapid quenching of the plasma gas at high temperature (e.g., 3700 K) and appropriate reactant concentrations. Quenching of tire plasma gas and production of titanium powder can be achieved by adiabatic expansion through a nozzle. Preliminary experimental data indicate that titanium powder of approximately 5 nm in size can be produced in an argon plasma rising a nozzle expansion approach.     

Optimization of a Natural Medium for Cellulase by a Marine Aspergillus niger Using Response Surface Methodology

The components of a natural medium were optimized to produce cellulase from a marine Aspergillus niger under solid state fermentation conditions by response surface methodology. Eichhornia crassipes and natural seawater were used as a major substrate and a source of mineral salts, respectively. Mineral salts of natural seawater could increase cellulase production. Raw corn cob and raw rice straw showed a significant positive effect on cellulase production. The optimum natural medium consisted of 76.9?% E. crassipes (w/w), 8.9?% raw corn cob (w/w), 3.5?% raw rice straw (w/w), 10.7?% raw wheat bran (w/w), and natural seawater (2.33 times the weight of the dry substrates). Incubation for 96?h in the natural medium increased the biomass to the maximum. The cellulase production was 17.80?U/g the dry weight of substrates after incubation for 144?h. The natural medium avoided supplying chemicals and pretreating substrates. It is promising for future practical fermentation of environment-friendly producing cellulase.     

Effect of reduction in yeast and enzyme concentrations in a simultaneous-saccharification-and-fermentation-based bioethanol process

The ethanol production cost in a simultaneous saccharification and fermentation-based bioethanol process is influenced by the requirements for yeast production and for enzymes. The main objective of this study was to evaluate—technically and economically—the influence of these two factors on the production cost. A base case with 5 g/L of baker’s yeast and an initial concentration of water-insoluble solids of 5% resulted in an experimental yield of 85%. When these data were implemented in Aspen Plus, yeast was assumed to be produced from sugars in the hydrolysate, reducing the overall ethanol yield to 69%. The ethanol production cost was 4.80 SEK/L (2.34 US$/gal). When adapted yeast was used at 2 g/L, an experimental yield of 74% was achieved and the estimated ethanol production cost was the same as in the base case. A 50% reduction in enzyme addition resulted in an increased production cost, to 5.06 SEK/L (2.47 US$/gal) owing to reduced ethanol yield.     

Lichtheimia blakesleeana as a new potencial producer of phytase and xylanase

Brazil is known for its great potential for production of renewable resources such as agro-industrial residues. These residues can be used as alternative sources of new products. Meanwhile, solid-state fermentation, with its advantages of energy conservation and pollution reduction, has been identified as a process of great potential for the production of bioactive compounds, especially enzymes. In the present work, a 2(3) factorial design was used to evaluate the effects of pH, temperature and moisture on the production of phytase and xylanase by Lichtheimia blakesleeana URM 5604 through the fermentation of citrus pulp. Statistical analyses of the results showed that the only the pH influenced the production of these enzymes, with the best phytase production (264.68 U/g) ocurring at pH 6.0, 34 °C, initial moisture 50%, after 48 hours of culture. The best conditions for xylanase production (397.82 U/g) were fermentation for 120 hours at pH 4.0, 26 °C and initial moisture of 70%. The best parameters for the simultaneous production of phytase (226.92 U/g) and xylanase (215.59 U/g) were determined to be initial moisture of 50%, pH 6.0, 26 °C, and 48 hours of fermentation.     

Use ofK L a as a criterion for scaling up the inulinase fermentation process

Applied Biochemistry and Biotechnology - The scale-up of inulinase production in aerated cultures ofCandida kefyr DSM 70106 was studied, taking into account the criterion of maintainingK L a...     

Investigation on alpha-galactosidase production by Streptomyces griseoloalbus in a forcefully aerated packed-bed bioreactor operating in solid-state fermentation condition

Solid-state fermentation (SSF) was carried out for the production of extracellular alpha-galactosidase by Streptomyces griseoloalbus. Soybean flour was the best solid substrate for alpha-galactosidase production. Packed-bed bioreactor performed well in enhancing the enzyme yield and resulted in a highest yield of 197.2 +/- 0.02 U/gds with a forced aeration of 2 vvm, which was approximately twofold the yield obtained in flasks. The alpha-galactosidase production was growth-associated, and the highest enzyme yield was obtained after 96 h of incubation. It is significant that this is the first report on alpha-galactosidase production by a filamentous bacterium in SSF using packed-bed bioreactor.