Showing papers by "Chalmers University of Technology published in 1977"
TL;DR: Later development, beginning with the dehydrogenation theory and experimental studies on the de-hydrogenative polymerization of p-hydroxycinnamyl alcohols, is reviewed in this article.
Abstract: Some pertinent results and views from the earlier history of lignin chemistry, pointing to the importance of the arylpropane skeleton, are outlined. Later development, beginning with the dehydrogenation theory and experimental studies on the dehydrogenative polymerization of p-hydroxycinnamyl alcohols, is then reviewed. Finally, recent degradative work resulting in a detailed picture of lignin structure is discussed.
1,586 citations
537 citations
01 May 1977
TL;DR: In this article, a mathematical model describing the power spectrum of myoelectric signals is presented, where the influences of electrode cofiguration and of biological parameters such as muscle-fiber radius, action-potential conduction velocity, spread of synapses over the innervation zone, number of fibers per motor unit, and electrode-to-muscle distance are expressed in terms of filter functions modifying the shape of the generator signal.
Abstract: Some essential elements of a mathematical model describing the power spectrum of myoelectric signals are presented. The influences of electrode cofiguration and of biological parameters such as muscle-fiber radius, action-potential conduction velocity, spread of synapses over the innervation zone, number of fibers per motor unit, and electrode-to-muscle distance are expressed in terms of filter functions modifying the shape of the power spectrum of the generator signal. Signal processing for parameter identification is described and results are listed. A few applications are discussed.
412 citations
TL;DR: In this article, the vibrational excitations and structure of CO chemisorbed on the clean Ni(100) surface have been investigated by high-resolution electron energy loss spectroscopy (EELS) and low-energy electron diffraction (LEED).
197 citations
01 Jan 1977
147 citations
TL;DR: The structure of the reducing end group in xylan can be written: -β-D-Xylp-(1→4)-β- D-Xyphexylp(1→3)-α-L-Rhap-( 1→2)-α -D-GalpA-(1∆)-D-xyphex-hex-2enuronic acid as mentioned in this paper.
Abstract: The structure of the reducing end group in xylan can be written: -β-D-Xylp-(1→4)-β-D-Xylp-(1→3)-α-L-Rhap-(1→2)--α-D-GalpA-(1→4)-D-Xyl
In alkaline media the reducing xylose group is easily isomerized and removed by a β-elimination which leads to a reducing galacturonic acid end group. The 1, 2-linkage between rhamnose and the galacturonic acid explains the retarding effect on the alkaline peeling. Even under fairly mild conditions the galacturonic acid group is converted to other groups which are very stable in alkaline media. Model experiments permit the conclusion that OH-3 in the reducing group is subjected to β-hydroxyelimination. The 3-deoxy-2-O-α-L-rhamnopyranosyl-D-threo-hex-2-enuronic acid group formed is unstable in acid medium and escapes observation by the techniques employed for determination of the end groups.
Upon prolonged alkaline treatment and increased proportion of these groups is lost and a rapid peeling proceeds until a xylose group with a 4-O-methylglucuronic acid substituent is liberated. The consecutive reactions of this group are similar to those of the galacturonic acid groups.
The formation of 3-deoxyaldonic acid end groups, an important stopping reaction in cellulose, is of minor importance in xylan.
The financial support from the 1959 Ars Fond for Teknisk och Skoglig Forskning samt Utbildning is gratefully acknowledged.
137 citations
TL;DR: The myoelectric activity of some of the posterior muscles of the back was studied quantitatively using signal amplitude estimation and power spectrum analysis andSpectral changes increased when the signal amplitude increased, indicating localized muscle fatigue.
106 citations
TL;DR: In this paper, the flatband voltage shift induced by hydrogen at the metal-oxide interface is a measure of the amount of hydrogen in the metal, which in turn reflects the chemical reactions on the surface.
99 citations
TL;DR: In this paper, an exchange-correlation functional with a nonlocal density dependence is proposed, which fulfills a sum rule stating that the exchange correlation hole should contain on electron, atom.
96 citations
TL;DR: Afferent electrical nerve stimulation is an approach showing many promises with regard to sensory feedback for powered prostheses that is well tolerated, can transmit fairly high amounts of information, and has several characteristics making it superior to electrocutaneous and vibrotactile devices when applied to prostheses.
Abstract: Afferent electrical nerve stimulation is an approach showing many promises with regard to sensory feedback for powered prostheses. It is well tolerated, can transmit fairly high amounts of information, and has several characteristics making it superior to electrocutaneous and vibrotactile devices when applied to prostheses. The feedback information is transferred in modulated form either by means of the current pulse amplitude (a.m.) or by the current pulse frequency (f.m.) A.M. stimulation should be applied in such a way that it gives rise to characteristic changes in the distribution of paresthesias with changing current. Used in this way it is not dependent upon minor changes in electrode position, it is easy to learn and gives high rates of information, even in untrained subjects. The number of channels that can be used in each nerve is, however, limited because of the large amount of axons necessary to achieve the spatial spread. F.M. stimulation is more difficult to learn than a.m. but gives the same rate of information transfer when used in trained individuals. Like a.m. it is not dependent upon minor changes in electrode position, but a smaller number of axons is needed to achieve discrimination. Thus several channels can be used in each nerve. Both with a.m. and f.m. stimulation a trained subject can discriminate five or six discrete levels with a rate of correct recognition of more than 75%, the amount of transmitted information being about 1·8 bits per symbol.
76 citations
TL;DR: In this paper, the authors studied the order and error constant of the Runge-Kutta method and showed that the maximum obtainable order is m+1 and the approximation of orderm+1 with least absolute value of the error constant has γ1=γ2=...=γ� n====== n======.
Abstract: Rational approximations of the form Σ
=0
a
i
q
i
/Π
=1
(1+γ
i
q) to exp(−q),qeC, are studied with respect to order and error constant. It is shown that the maximum obtainable order ism+1 and that the approximation of orderm+1 with least absolute value of the error constant has γ1=γ2=...=γ
n
. As an application it is shown that the order of av-stage semi-implicit Runge-Kutta method cannot exceedv+1.
TL;DR: In this article, self-consistent energy-band calculations on the full 18-atom/unit-cell ternary alloys MRh/sub 4/B4 (M = Y, Er and Ho) are reported and used to discuss their superconducting and magnetic properties.
Abstract: Results of ab initio self-consistent energy-band calculations on the full 18-atom/unit-cell ternary alloys MRh/sub 4/B4 (M = Y, Er and Ho) are reported and used to discuss their superconducting and magnetic properties--including the observation of reentrant magnetism in the normal state at T < 0.9 K in ErRh/sub 4/B/sub 4/.
01 Dec 1977
TL;DR: In this article, the surface terminates the crystal in an integral number of electrically neutral Na-ONa sandwiches, with a bulk-like inter layer spacing, and the effective Debye temperature for the Na(110) surface was found to be 107 K.
TL;DR: In this article, a quantum-mechanical theory of the inelastic scattering of slow electrons by molecules adsorbed on metal surfaces is presented, and the differential cross section for vibrational excitation of one single molecule is computed.
TL;DR: Evidence is presented that the product water formed in the reduction of 9 by fully reduced tree lactase, is indeed coordinated to Type 2 Cu”, and in the oxidized protein this ligand exchanges very slowly with bulk water since most of it remains even after 30 min.
TL;DR: Using an atomic-beam magnetic resonance apparatus connected on-line with the ISOLDE isotope separator, CERN, hyperfine structure measurements have been performed in the 2S12 electronic ground state of some cesium isotopes.
TL;DR: In this paper, the energy levels and charge densities for ThO2 and UO2 were calculated in a molecular cluster approximation, using spin unrestricted Hartree-Fock-Slater and relativistic Dirac-slater models.
TL;DR: The NMR technique for measuring magnetic susceptibility has been applied and the availability of super-conducting magnets has increased, giving a more direct measure of the spin-states of the oxidized and reduced protein.
TL;DR: In this article, a systematic theoretical study of atoms chemisorbed on free-electron-like metal surfaces is performed using an earlier published embedding scheme, and the results of the improved model support the essential findings of the earlier used model with important improvements of some obvious shortcomings.
TL;DR: In this article, a number of galvanic cells using anodes made from Mg, Ca, and Zn have been tested at elevated temperatures, and a Mg|Li1.72Mg0.14SO4|MnO2 cell gave an open-circuit voltage of 2.3 V and a power density of 400 W/kg at 745°C.
TL;DR: In this paper, the dependence of the binding energy of an adatom on the surface geometry of a jellium-plus-adatom was investigated for chemisorption on a real metallic substrate.
TL;DR: In this article, the authors used a new laser light scattering apparatus to measure the propyl stearate monolayers and determined the elasticity and viscosity of the monolayer.
TL;DR: Attempts have been made to distinguish signals that reflect mechanistically important states of the enzyme from those that have no catalytic relevance, and the catalytic significance of one of the rhombic high-spin Fe3’ signals observed during anaerobic reduction has been questioned.
TL;DR: In this paper, the optical constants of Ca have been determined from reflectance measurements in the range 2-11 eV. Good agreement with a calculation of the optical joint density of states is obtained.
Abstract: The optical constants of Ca have been determined from reflectance measurements in the range 2-11 eV. Good agreement with a calculation of the optical joint density of states is obtained. The origin of the absorption spectrum has been analyzed using plots of so-called optical surfaces. Studies of the dielectric function reveal two volume and two surface plasmons.
TL;DR: In this paper, the region around the ν-carbides M 6 C and M 12 C in the quaternary system FeWCCr at 1250°C has been determined by metallography, X-ray diffraction and electron microprobe analysis.
TL;DR: In this paper, a sheet containing a crack and loaded in Mode I has been studied with a one-dimensional method according to Dugdale, where the material is assumed to exhibit time-independent continuous damage when loaded.
TL;DR: In this paper, the retention index and relative retention were determined for trimethylsilyl esters/ethers of approximately 170 acids and lactones for silicone stationary phases OV-1 (methyl), OV17 (50% phenyl), and QF-1(50% trifluoropropyl).
Abstract: Retention index and relative retention were determined for trimethylsilyl esters/ethers of approximately 170 acids and lactones. The structural categories studied were aldonic (hydroxy monocarboxylic) acids, aldaric (hydroxy dicarboxylic) acids, non - carbohydrate (mainly dicarboxylic) acids, and lactones of aldonic acids. Data are given for the silicone stationary phases OV-1 (methyl), OV-17 (50% phenyl) and QF-1 (50% trifluoropropyl). Diagrams of the retention index on the non-polar phase versus the increase in the retention index on either of the other phases are useful for qualitative analysis. The dependence of retention on structure is interpreted in terms of non-polar and polar interactions between solute and stationary phase. Structural units of the solutes are attributed retention index increments which permit predictions of retention from structure or structure from retention. The reference retention index data can be used in
temperature - programmed analalysis if retentions are measured as methylene unit (MU) values. Differences between the retention index and MU concepts are discussed.