The effects of agitation and aeration on the production of gluconic acid byAspergillus niger

Applied Biochemistry and Biotechnology - The effects of agitation and aeration in the production of gluconic acid byAspergillus niger from a glucose medium were investigated. Experiments were...     

A polarographic and spectral study of some C- and N-nitroso compounds.

A wide range of N-nitroso compounds was investigated polarographically and spectrophotometrically. In general, the =N-N0 group is reduced in a 4-electron step in acidic media, which is most suitable for differential pulse polarographic analysis at the trace level. If the groups R and/or R' attached to the nitrosamine group are saturated entities, then the resulting differential pulse polarographic peaks are broad and of little use in the resolution of mixtures. The limit of detection is of the order of 10^-6M. If R and R' are unsaturated, the polarographic peaks are much sharper, mixtures can be resolved and the limit of detection is of the order of 10^-7M, C-Nitroso and C-nitro compounds are best determined by differential pulse polarography, because the waves are comparatively large and sharp, and because the reductions occur at relatively positive potentials where co-extractible interferences from foods, etc., will interfere to a minimal degree.     

Effect of agitation on removal of acetic acid from pretreated hydrolysate by activated carbon

The effect of agitation on the adsorption of acetic acid by activated carbon was tested utilizing an external mass transfer-diffusion model. Simulated pretreated biomass was contacted with activated carbon under prescribed conditions of temperature and agitation. Adsorption isotherm studies are presented as well as batch kinetic rate studies. Use of these data enabled the determination of isotherm constants, an external mass transfer coefficient, and an effective diffusivity for each agitation rate studied. The external film coefficient results ranged from 33.62 μm/s to a complete absence of external mass transfer resistance, and the diffusivity results ranged from 0.8625 to 10.70 μm²/s. The optimum combination of no external film resistance, and highest diffusivity, 10.70 μm²/s, occurred at 250 rpm and 25°C. The results of these models and the experimental parameters suggested an efficacious method and conditions for the removal of this undesirable chemical.     

Photoemission studies of polythiophene and polyphenyl films produced via surface polymerization by ion-assisted deposition

Conducting polymer films are grown by mass-selected, hyperthermal thiophene ions coincident on a surface with a thermal beam of organic monomers of either alpha-terthiophene (3T) or p-terphenyl (3P) neutrals. Mass spectrometry and X-ray photoelectron spectroscopy previously verified polymerization of both 3T and 3P by 200 eV C(4)H(4)S(+) during surface polymerization by ion-assisted deposition (SPIAD). The electronic structure of these films are probed here by ultraviolet photoelectron spectroscopy (UPS) and polarized near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and compared with similar spectra of evaporated films. The conducting polymer films formed by SPIAD display new valence band features resulting from a reduction in both their band gap and barrier to hole injection, which are calculated from the occupied and unoccupied valence band states measured by UPS and NEXAFS. These changes in film electronic structure result from an increase in the electron conjugation length and other changes in film structure induced by SPIAD.     

Separation optimization for the recovery of phenyl ethyl alcohol

Phenyl ethyl alcohol is a compound that occurs naturally in flower petals and in many common beverages, such as beer. Desire for the floral, rose-like notes imparted by phenyl ethyl alcohol has created a unique niche for this chemical in flavor and fragrance industries. Phenyl ethyl alcohol can be produced by Saccharomyces cerevisiae via bioconversion. Often this method of production results in extremely low yields, thus placing a great deal of importance on recovery and purification of the valuable metabolite. To determine the best method for recovering the chemical, a primary recovery step and a secondary recovery step were developed. The primary recovery step consisted of comparing dead-end filtration with crossflow ultrafiltration. Crossflow ultrafiltration was ultimately selected to filter the fermentation broth because of its high flow rates and low affinity for the product. The secondary recovery step consisted of a comparison of liquid-liquid extraction and hydrophobic resin recovery. The hydrophobic resin was selected because of its higher rate of recovery and a higher purity than the liquid-liquid extraction, the current practice of Brown-Forman.     

Photovoltaic Behaviour of Titanyl Phthalocyanine Thin Films and Titania Bilayer Films

Summary: Titanyl phthalocyanine (TiOPc) thin films were prepared using evaporation and surface polymerization by ion-assisted deposition (SPIAD) in a vacuum deposition system. These films were characterized by means of ultraviolet and X-ray photoelectron spectroscopy as well as UV/Vis absorption spectroscopy. Valence band and elemental content indicated that phthalocyanine electronic and chemical structures were largely preserved during SPIAD. Further, bilayer thin films of titania (TiO₂) and SPIAD TiOPc were prepared. TiO₂ film was deposited by reactive magnetron sputtering of TiO₂ target. Study of the structured samples was focused on the optical and electrical properties of the composite films. The films were characterized by non-contact photovoltage measurements and UV-Vis spectroscopy. These results suggest there is a possibility to use these bilayer thin films in photovoltaic solar cells, however further experiments to improve conductivity of the films will be required.     

Measurement of rheology of distiller's grain slurries using a helical impeller viscometer

Current research is focused on developing a process to convert the cellulose and hemicellulose in distiller's grains into fermentable sugars, increasing both ethanol yield and the amount of protein in the remaining solid product. The rheologic properties of distiller's grain slurries were determined for concentrations of 21, 23, and 25%. Distiller's grain slurries are non-Newtonian, heterogeneous fluids subject to particle settling. Traditional methods of viscosity measurement, such as cone-and-plate and concentric cylinder viscometers, are not adequate for these fluids. A helical impeller viscometer was employed to measure impeller torque over a range of rotational speeds. Newtonian and non-Newtonian calibration fluids were utilized to obtain constants that relate shear stresses and shear rates to the experimental data. The Newtonian impeller constant, c, was 151; the non-Newtonian shear rate constant, k, was 10.30. Regression analysis of experimental data was utilized for comparison to power law, Herschel-Bulkley, and Casson viscosity models with regression coefficients exceeding 0.99 in all cases.     

Farrell sets for harmonic functions

Let denote a relatively closed subset of the unit ball of . The purpose of this paper is to characterize those sets which have the following property: any harmonic function on which satisfies on (where 0$">) can be locally uniformly approximated on by a sequence of harmonic polynomials which satisfy the same inequality on . This answers a question posed by Stray, who had earlier solved the corresponding problem for holomorphic functions on the unit disc.