Simultaneous hydrolysis and fermentation of pulp mill primary clarifier sludge

Bioconversion of sludge from the primary clarifier of a sulphite pulping operation to ethanol offers a number of advantages over conventional disposal options. The amount of material which must be disposed of is reduced while, at the same time, salable and environmentally friendly fuel-ethanol is produced. In this study, primary clarifier sludge (PCS) was shown to be hydrolysed to produce fermentable sugars at a rate proportional to enzyme loading. Initial (1 hour) hydrolysis rates as high as 12.6 g reducing sugar/L · h were observed at an initial enzyme loading of 10 filter paper units (FPU)/g. Hydrolysis was inhibited by spent sulphite liquor (SSL), an inhibition which could be completely overcome by fermenting the SSL to remove sugars. Surfactants were found to only marginally improve the production of sugars. To reduce the deleterious effects of end product inhibition, single stage simultaneous hydrolysis and fermentation (SHF) was carried out using cellulase enzymes and Saccharomyces cerevisiae.     

Theory and experiment on the three-dimensional motion of a freely suspended spherical particle at the entrance to a pore at low Reynolds number

This paper examines the three dimensional approach of a neutrally buoyant sphere of any size to a circular hole in a plane wall at very low Reynolds number. The analysis differs from previous studies, largely applied to the multipore filter, in that the authors investigate the three dimensional hydrodynamic interaction of the sphere with the entrance geometry of the pore in the limit of zero inertia. The problem is first exactly formulated as the linear superposition of fundamental Stokes flows for rotation and translation of the sphere and flow past a stationary sphere. Approximate solutions are then obtained for the deviation of sphere trajectories from fluid stream lines and the results compared with laboratory model experiments in a low Reynolds number settling tank. The theory and experiment show that because of the hydrodynamic interaction sphere trajectories and fluid streamlines deviate significantly as the opening is approached, that all spheres eventually enter the pore regardless of their initial position, but that a non-uniform concentration profile develops with large increases in concentration near the walls of the orifice in the vicinity of the opening. The results provide a basic mechanism to explain the onset of Fahraeus phenomenon for red cells entering small blood vessels and glass tubes.     

Measurement of O2-N2 binary sorption on 5A zeolite by isotope tracer and perturbation chromatography

Isotope tracer chromatography allows to extract simply and quickly multi component adsorption data and is demonstrated for single component and binary adsorption equilibria for O₂ and N₂ on 5A zeolite as an example. In this modification of conventional tracer chromatography, a small pulse of an isotope tracer is injected in an adsorbable carrier gas (pure or multicomponent mixture) flowing through a column filled with adsorbent and is designed to operate at almost uniform pressure. Isotherm parameters are readily extracted by fitting measurements of residence times at various pressures and carrier composition. The isotherms were in excellent agreement with volumetric measurements. Isotope tracer chromatography is shown to be superior to perturbation chromatography since the influence of the injection volume on the carrier gas composition is substantially smaller for tracer experiments. Unfortunately, this new improved gas chromatographic technique requires rather expensive isotopes. The strength of this new approach lies in the advantage of working with small adsorbent samples (1 g) making a rapid screening of newly developed materials possible.Nomenclature K _exp,tr,i experimental tracer adsorption constant (mol/kg pure adsorbent/Pa) - K _i Henry adsorption equilibrium constant (mol/kg pure adsorbent/Pa) - K _i,part partition coefficient - K _pert composite Henry constant (mol/kg pure adsorbent/Pa) - L column length (m) - L _i Langmuir adsorption constant (1/Pa) - n _i amount adsorbed on the solid (mol/kg adsorbent) - N _i adsorbent loading (Pa) - p total pressure (Pa) - p _i partial pressure of component i (Pa) - p _in column inlet pressure (Pa) - p _out column outlet pressure (Pa) - q _i amount of component i in the micropores (Pa) - R gas constant (J/mol/K) - t time (s) - T temperature (K) - v _f superficial velocity in adsorbent column (m/s) - v _out velocity at the outlet of the column (m/s) - V _inlet volumetric flow rate at inlet conditions (ml/s) - x molar fraction of tracer - y molar fraction of component i in the carrier gas - z axial coordinate (m) Greek letters _ext bed voidage, external porosity - _macr macropore porosity [_macr= _p (1–_ext)] - _micr micropore porosity - _tot total porosity - _p pellet porosity - volume fraction of binder material - _d dead time (s) - _tracer tracer residence time (s) - _pert perturbation residence time (s) - _crys crystal density (kg/m³)     

Examination of the relationship between cracking resistance,hardness, and strength of steels at different temperatures and strain rates

The results are presented of measurements of Brinell hardness HB of 15Kh2NMFA and 10G2FB steels in the temperature range 77 T 373K. The resultant HB values are compared with strength, impact toughness, and cracking resistance in the entire temperature range examined. The relationship between cold brittleness of the steels and the form of the HB-T curves is analyzed on the basis of the concept of the characteristic temperature of contact deformation. The results show that the relationship between hardness and yield limit depends in a complicated manner on the test temperature and is determined by the plastic deformation mechanisms operating in each individual case. Correlation dependences are presented for determining the height of the stretching zone and stress intensity factor on the basis of HB values at different temperatures and strain rates. A criterion K_Ic/HB is introduced to predict the cracking resistance inside the examined temperature range on the basis of the values of K_Ic and HB at the boundaries of this range.Translated from Problemy Prochnosti, No. 2, pp. 14–17, February, 1991.     

The U-Zr (Uranium-Zirconium) system

This work was supported by the Department of Energy through the Joint Program on Critical Compilations of Physical and Chemical Data, coordinated through the Office of Standard Reference Data (OSRD), National Institute of Standards and Technology. Literature searched through 1985. Dr. Peterson is the ASM/NIST Data Program Category Editor for binary actinide alloys.     

Investigations of development process of high hollow beveled microneedles using a combination of ICP RIE and dicing saw

Micromachined needles provide a promising technology for painless delivery of molecules or foreign substance into a living cell. Over the recent years, a variety of different microneedle shapes and materials have been studied and have shown their facility to disrupt stratum corneum layer to increase the skin permeability. In this paper, we described an alternative process to fabricate high and beveled hollow out-of-plane microneedles. Silicon microneedles dimensions are 40–60 μm in inner diameter, 150–200 μm in outer diameter and over 700 μm in height. Tip angles reached are from 30° to 45°.     

Surface energy-mediated fibronectin adsorption and osteoblast responses on nanostructured diamond

Nanostructured diamond have potential applications in many biomedical related fields and demonstrated extraordinary capacity to influence cellular responses. Studying the surface property of nanodiamond and its influence to protein adsorption and subsequent cellular responses along with the mechanism behind such capacity becomes more important. Here the role of surface energy associated with nanostructured diamond in modulating fibronectin and osteoblast(OB, bone forming cells) responses was investigated. Nanocrystalline diamond(NCD) and submicron crystalline diamond(SMCD) films with controllable surface energy were prepared by microwave-enhanced plasma chemical vapor deposition(MPCVD) techniques. Fibronectin adsorption on the diamond films with varied surface energy values was measured via the enzyme-linked immunosorbent assay(ELISA) and the relationship between the surface energy and fibronectin adsorption was studied. The result indicated that fibronectin adsorption on nanostructured surfaces was closely related to both surface energy and material microstructures. The spreading and migration of OB aggregates(each containing 30–50 cells) on the NCD with varied surface energy values were also studied. The result indicates a correlation between the cell spreading and migration on nanodiamond and the surface energy of nanostructured surface.     

Measurement-based modeling of contact forces and textures for haptic rendering

Haptic texture represents the fine-grained attributes of an object's surface and is related to physical characteristics such as roughness and stiffness. We introduce an interactive and mobile scanning system for the acquisition and synthesis of haptic textures that consists of a visually tracked handheld touch probe. The most novel aspect of our work is an estimation method for the contact stiffness of an object based solely on the acceleration and forces measured during stroking of its surface with the handheld probe. We establish an experimental relationship between the estimated stiffness and the contact stiffness observed during compression. We also measure the height-displacement profile of an object's surface enabling us to generate haptic textures. We show an example of mapping the textures on to a coarse surface mesh obtained with an image-based technique, but the textures may also be combined with coarse surface meshes obtained by manual modeling.