Showing papers by "Chalmers University of Technology published in 1986"
TL;DR: In this paper, a HPLC method was developed for separation and quantitative determination of inositol tri-, tetra-, penta-, and hexaphosphates, and compared to phytate determinations by two iron precipitation methods.
Abstract: A HPLC method was developed for separation and quantitative determination of inositol tri-, tetra-, penta-, and hexaphosphates. The method included extraction of inositol phosphates with HCI, separation of the inositol phosphates from the crude extract by ion-exchange chromatography, and ion-pair C18 reverse phase HPLC analysis using formic acid/methanol and tetrabutylammonium hydroxide in the mobile phase. The inositol 3–6 phosphates of raw and extruded bran, soy flour, and intestinal contents were determined by HPLC and compared to phytate determinations by two iron precipitation methods. Inositol 3–5 phosphates were found in extruded products and intestinal contents. The HPLC method was rapid and gave reproducible values, which differed from those obtained by the precipitation methods in some samples.
321 citations
TL;DR: In this article, in situ measurements with a benthic flux chamber, in which dissolved oxygen and pH were maintained near ambient values (regulated flux-chamber), showed that the sediment did not release any of these ions but instead removed Co, Mn, Co, and Fe from the overlying water.
300 citations
TL;DR: In this article, a cross-linked montmorillonite was introduced by cation exchange with polymeric Ti cations, formed by partial hydrolysis of TiCl4 in HCl.
Abstract: Titanium was introduced into the montmorillonite structure by cation exchange with polymeric Ti cations, formed by partial hydrolysis of TiCl4 in HCl. On further hydrolysis and heating, TiO2 pillars in the form of anastase were formed between the montmorillonite layers. The resulting TiO2-cross-linked montmorillonites possessed surface areas in the range 200–350 m2/g and pore volumes of about 0.2 cm3/g and were thermally and hydrothermally stable to 700°C. The basal spacing of products heated at temperatures > 200°C was about 28A, as determined by X-ray powder diffraction and by N2-desorption pore-size analysis. The surface area increased and the pore volume decreased with increasing HCl-concentration in the Ti-solution. The uptake of TiO2 by the montmorillonite, the surface area, and the pore volume increased with increasing amount of Ti added in the preparation, to about 10 mmoles of Ti/g of montmorillonite. A further increase in the amount of Ti added resulted in a decrease in surface area, but the pore volume and the uptake of TiO2 remained almost constant. The high porosity and the interlayer spacing of the product are consistent with a structure similar to that previously proposed for smectites, cross-linked with hydroxy-Al oligocations.
290 citations
TL;DR: In this paper, the authors derived new estimates for the rate of convergence of the conjugate gradient method by utilizing isolated eigenvalues of parts of the spectrum and compared the derived estimates of the number of iterations with the number actually found for some elliptic difference equations and for a similar problem with a model empirical distribution function.
Abstract: We derive new estimates for the rate of convergence of the conjugate gradient method by utilizing isolated eigenvalues of parts of the spectrum. We present a new generalized version of an incomplete factorization method and compare the derived estimates of the number of iterations with the number actually found for some elliptic difference equations and for a similar problem with a model empirical distribution function.
285 citations
TL;DR: In this article, the microstructure of cast aluminum alloys based on Al-7 pct Si-0.3 pct Mg (A356) has been investigated as a function of Fe and Cr content and solidification rate.
Abstract: The detailed microstructure of cast aluminum alloys based on Al-7 pct Si-0.3 pct Mg (A356) has been investigated as a function of Fe and Cr content and solidification rate. It was found that the coarse β phase (FeSiAl5) platelets, which form during solidification of alloys containing Fe, are replaced by “Chinese script” α(bcc) [(Cr, Fe)4Si4Al13] dendritic particles when Cr is added. Coarse π (FeMg3Si6Al8) phase and fine α(bcc) precipitates were found in all of the investigated alloys. Quantitative metallography showed that the length of β phase platelets and the arm length of α(bcc) dendrites increased with decreasing solidification rate and increased Fe content. The T6 heat treatment resulted in the dissolution of π phase and the uniform fine scale precipitation of β′(Mg2Si) in the aluminum rich phase.
202 citations
TL;DR: In this article, the suitability of total carbonate production instead of oxygen consumption as a measure of benthic respiration has been investigated, and it was shown that the flux of the carbonate, corrected for CaCO3 precipitation/dissolution, is a suitable measure of Benthic mineralization in sediments where methane production can be neglected.
Abstract: The suitability of total carbonate production instead of oxygen consumption as a measure of benthic respiration has been investigated. In situ fluxes of total carbonate, oxygen, calcium, total alkalinity, nutrients, and sulfide across the sediment-water interface were measured in diver-operated benthic flux chambers. Two chambers were run in parallel to test the influence of oxygen and pH levels on total carbonate production. In one, oxygen and pH were kept constant near ambient levels; in the other, benthic respiration was allowed to deplete oxygen and lower the pH. We found that the flux of total carbonate, corrected for CaCO3 precipitation/dissolution, is a suitable measure of benthic mineralization in sediments where methane production can be neglected. The production rate of total carbonate was not seriously affected as long as the oxygen concentration remained > 100 µM.
183 citations
TL;DR: In this paper, southern pine and aspen flakes were acetylated with acetic anhydride alone without cosolvent or catalyst by a simple dip procedure, which greatly shortens reaction time and simplifies chemical recovery.
Abstract: Southern pine and aspen flakes were acetylated with acetic anhydride alone without cosolvent or catalyst by a simple dip procedure. The new procedure greatly shortens reaction time and simplifies chemical recovery. Acetylation weight gains of 15% to 20% can be achieved in 1 to 3 hours with southern pine flakes and in 2 to 4 hours with aspen flakes. Flakeboards made from acetylated southern pine or aspen flakes absorbed much less water, both in water-soaking tests and when subjected to humid air, and swelled at a lower rate and to a lower extent than did control boards. Hygroscopicity of the resulting flakeboards decreased with increased level of wood acetylation. The equilibrium moisture content (EMC) for flakeboards made from acetylated flakes was lower at each relative humidity tested than that of control boards.
178 citations
TL;DR: A class of preconditioning methods depending on a relaxation parameter is presented for the solution of large linear systems of equationAx=b, whereA is a symmetric positive definite matrix.
Abstract: A class of preconditioning methods depending on a relaxation parameter is presented for the solution of large linear systems of equationAx=b, whereA is a symmetric positive definite matrix. The methods are based on an incomplete factorization of the matrixA and include both pointwise and blockwise factorization. We study the dependence of the rate of convergence of the preconditioned conjugate gradient method on the distribution of eigenvalues ofC−1A, whereC is the preconditioning matrix. We also show graphic representations of the eigenvalues and present numerical tests of the methods.
163 citations
TL;DR: Fluxes of trace metals across the sediment-water interface were measured in situ at 6 m depth in Gullmarsfjorden, Sweden, using diver-operated stirred benthic flux-chambers as mentioned in this paper.
154 citations
119 citations
TL;DR: Calculations are presented describing the influence of external diffusion in the kinetics of solid-phase immunoassays with systems where one reactant is immobilized at the surface of a sphere of arbitrary radius.
TL;DR: The myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque, suggesting that a considerable amount of the muscle contraction was used to control the posture.
TL;DR: The estimated number and cause of head injuries in Sweden are discussed and the need of head protection is stressed.
Abstract: The estimated number and cause of head injuries in Sweden are discussed Head injuries are common in many activities and the need of head protection is stressed
TL;DR: It is found that soliton coalescence can be avoided by proper phase shifting of consecutive pulses and that a phase shift of π/2 minimizes the initial mutual interaction.
Abstract: Mutual interaction between soliton pulses may severely limit the maximum bit rate of a soliton-based optical communication system We present explicit analytical results for soliton separation as a function of propagation distance in the presence of mutual pulse interaction In particular, we find that soliton coalescence can be avoided by proper phase shifting of consecutive pulses and that a phase shift of π/2 minimizes the initial mutual interaction
TL;DR: In this paper, a detailed analysis of the phenomenon of cross-saturation is presented and it is shown that in a smooth-air-gap quadrature-phase machine this phenomenon is similar to the demagnetizing effect of crossmagnetizing armature reaction in a d.c.m. machine.
Abstract: A detailed analysis of the phenomenon of cross-saturation is presented and it is shown that in a smooth-air-gap quadrature-phase machine this phenomenon is similar to the phenomenon of the demagnetizing effect of cross-magnetizing armature reaction in a d.c. machine. In a quadrature-phase smooth-air-gap machine the resultant air-gap flux density distribution is decreased over one half of the pole-pitch and is increased under the other half of the pole-pitch and due to saturation the decrease is greater than the increase. Thus under saturated conditions, if the resultant m.m.f. distribution is displaced from the magnetic axes of the windings, a change in the quadrature-axis magnetizing current will cause a change of flux linkage in the direct-axis winding and vice versa, a change in the direct-axis magnetizing current will cause a change of flux linkage in the quadrature-axis winding. It is an important result that cross-saturation can also exist if the m.m.f. distributions are assumed to be sinusoidal. A physical derivation of the cross-saturation coupling factor is presented and a test is described which shows the existence of cross-saturation. A theoretical analysis of the experiment gives results which are in good agreement with the experimental results.
TL;DR: In this article, the dynamics in a Lennard-Jones system close to the glass transition were analyzed using a kinetic model presented in an earlier paper, based on the Zwanzig-Mori procedure for deriving formally exact transport equations combined with mode-coupling approximations.
Abstract: Numerical results on the dynamics in a Lennard-Jones system close to the glass transition are presented, using a kinetic model presented in an earlier paper. The theory is based on the Zwanzig-Mori procedure for deriving formally exact transport equations combined with mode-coupling approximations. Results for a number of different dynamical quantities of experimental interest are presented and the model is shown to reproduce many of the characteristic features of a liquid-glass transition. Comparisons are made with available computer simulation data and analytical results for the same mode-coupling model.
TL;DR: Cette chimisorption semble etre le resultat d'etats atomiques d non remplis sur ces «marches», couverte par une couche dense d'atomes d'hydrogene.
Abstract: We report the observation of molecular ${\mathrm{H}}_{2}$ chemisorption at the edge sites of a stepped Ni (100) surface that is covered with a dense layer of atomic hydrogen. No such state is observed on the flat Ni (100) surface. We suggest that this ${\mathrm{H}}_{2}$ chemisorption state can form stably as a result of residual unfilled $d$ states at these step sites, while the dissociative channel is blocked by the saturated atomic adsorbate layer.
TL;DR: In this article, the effect of freestream turbulence on the flow past a circular cylinder (tube) was studied experimentally for Reynolds numbers between 2 × 10 4 and 6 × 104.
TL;DR: In this article, the Li 2 SO 4 -Li 2 CO 3 binary system has been studied using DSC, X-ray diffraction and electrical conductivity measurements, and it has been suggested that high conductivity in the interface region between the finely dispersed crystallites in the eutectic mixture.
TL;DR: In this paper, the deformation history of the SW-Swedish gneiss belt has been investigated and the principle deformation of central Sweden is suggested to be D4; the ‘Mylonite zone’ of western Sweden appears to have been initiated before D3.
TL;DR: In this paper, a chargeconsistent version of the relativistic extended Huckel method REX is presented and the diagonal matrix elements are corrected for occupations of individual orbitals on the same atom using derivatives from atomic Dirac-Slater calculations and for external charges.
TL;DR: In this paper, a monolithic gas flow sensor was designed and fabricated by use of micromachining of silicon and its operation is based on the cooling of an electrically heated mass by the gas flow, and detection of the mass's temperature by a diode.
Abstract: A novel small monolithic gas flow sensor has been designed and fabricated by use of micromachining of silicon. Its operation is based on the cooling of an electrically heated mass by the gas flow, and detection of the mass's temperature by a diode. The small size, 0.4 mm by 0.3 mm by 30 µm, of the hot part of the sensor gives a fast thermal response (time constant 50 ms). By using polyimide as a thermal insulator a high gas flow sensitivity is achieved, The shape of the sensor will present very little obstruction to the gas flow and also makes it easy to mount.
TL;DR: In this article, the densities of dislocations trapped in coherent twin boundaries may be used to provide a direct and quantitative comparison of the extent of intragranular slip in the three regions of behaviour associated with superplasticity.
TL;DR: A new generation of FCC catalyst technology has emerged with tailor-made catalysts for higher structural stability and attrition strength, more complete CO combustion during regeneration, reducing SOx emissions from FCC stacks, enhancing the gasoline octane number, passivating the harmful effects of metals like Ni and V accumulating on the catalyst, etc., as discussed by the authors.
TL;DR: Numerical results on liquid-glass transitions for Lennard-Jones systems are presented, based on a kinetic theory presented in two earlier papers, and detailed comparison is made with available computer simulation data.
Abstract: Numerical results on liquid-glass transitions for Lennard-Jones systems are presented, based on a kinetic theory presented in two earlier papers. Detailed comparison is made with available computer simulation data and shows quite good agreement.
TL;DR: In this article, the Lp-estimates for solutions of the nonlinear, spatially homogeneous Boltzmann equation were studied and the molecular forces considered include inverse kth-power forces with k > 5 and angular cut-off.
Abstract: This paper studies Lp-estimates for solutions of the nonlinear, spatially homogeneous Boltzmann equation. The molecular forces considered include inverse kth-power forces with k > 5 and angular cut-off.
TL;DR: In this article, it was shown that plane rotors with one or two particles free to move, subject to viscous damping, exhibit autobalancing, a property attributed to non-autonomous systems possessing an hyperbolic stable fixed point in the (non-extended) phase space for an open domain in parameter space.
10 Sep 1986-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the fiber technique has been applied to X-rays by the use of a thin capillary of glass and the critical angles for total reflection have been measured and compared with calculated values from a simple theory.
Abstract: The fiber technique has been applied to X-rays by the use of a thin capillary of glass. The critical angles for total reflection have been measured and compared with calculated values from a simple theory. The ability of bending the X-ray beam within the fiber has been demonstrated.
TL;DR: The results indicate that the physical distribution of the sole at the heel and toe, as well as the material, is of great importance for the torque developed.
Abstract: Rotation torque is known to be one of many factors affecting the risk of injury in athletics. Experiments were performed to examine the torque and friction on different sport shoes when sliding on an artificial turf. An apparatus was constructed in which it is possible to measure simultaneously the torque and the frictional force developed when a shoe slides on a surface. Measurements were made for 25 different shoes on an artificial turf. The frictional force was independent of the speed in the range 1 to 5 m/s. The torque was dependent on the physical distribution of the texture of the sole and slightly dependent on the frictional force. The results indicate that the physical distribution of the sole at the heel and toe, as well as the material, is of great importance for the torque developed.
TL;DR: In this paper, MNDO calculations on polyaniline segments of the polymer were carried out to get a quantitative picture of the geometry, and the results indicated that the structure is unchanged upon protonation and that the injected charge is delocalized.