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Showing papers by "Technical University of Denmark published in 1983"


Book ChapterDOI
TL;DR: An overview of the 13 Carbon-Nuclear magnetic resonance (13 C-NMR) spectroscopy of monosaccharides can be found in this paper, where an almost complete collection of 13 C- NMR chemical shifts of polysaccharides, their methyl glycosides, and acetates is presented.
Abstract: Publisher Summary This chapter provides an overview of the 13 Carbon-nuclear magnetic resonance ( 13 C-NMR) spectroscopy of monosaccharides. The 13 C-NMR spectroscopy has become increasingly important as a tool for the characterization and structural elucidation of sugars and their derivatives. Although 13 C-NMR is closely related to 1 H-NMR spectroscopy, especially when both types of spectra are recorded with Fourier-transform instruments, the two techniques are sufficiently different to be valuable complements to each other. In many cases, in particular when dealing with complex molecules such as polysaccharides, the amount of information obtainable from 1 H-NMR spectra is limited as compared to that revealed by 13 C- NMR spectra. This chapter provides an almost complete collection of 13 C- NMR chemical shifts of monosaccharides, their methyl glycosides, and acetates, along with the examples of shift data for as many different types of monosaccharide derivative as possible. It also provides details on sampling techniques and assignment techniques, and discusses the identity of monosaccharides, their structure determination, and conformational analysis .

1,273 citations


Journal ArticleDOI
TL;DR: A review of anaerobic treatment of wastewater in fixed film reactors is presented, with emphasis laid on kinetic parameters like growth constants, substrate removal rates and growth yields.

490 citations


Journal ArticleDOI
TL;DR: In this paper, the cutting forces parallel and perpendicular to the cutting direction are measured for various parameters, and the results correlated to the formation of chips and the wear of the tool, and a new chip preparation technique is used for the investigation.

357 citations


Journal ArticleDOI
TL;DR: In this paper, a search for electron pairs produced in p p collisions at s = 550 GeV was carried out, and it was reported that eight events which were interpreted as resulting from the process p +p→Z 0 + anything, followed by the decay Z0→e++e− or Z 0→e−e−+γ, where Z0 is the neutral Intermediate Vector Boson postulated by the unified electroweak theory.

350 citations


Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of the magnetic hyperfine field of microcrystalline goethite has been studied in detail and the results have been compared to the behaviour of well-crystallized Goethite.

315 citations


Journal ArticleDOI
TL;DR: In this paper, a low-temperature approximation for the reduction in the magnetic hyperfine splitting of the Mossbauer spectrum of a microcrystal was derived for arbitrary magnetic energy, and explicit expressions for particles with special types of magnetic anisotropy and for particles exposed to external magnetic fields.

296 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that if a consistent expression for the shear coefficient, such as those given by Cowper [1] or Stephen [2], is used in Timoshenko's beam theory, then very high accuracies can be expected for the natural frequencies, even for wavelengths of the same magnitude as the transverse dimension of the beam.

205 citations


Journal ArticleDOI
TL;DR: Evidence is presented to suggest that proteins with properties similar to those of the barley inhibitor are present in other cereals including wheat and rye.
Abstract: A protein inhibitor of endogenous α-amylase 2 has been isolated from germinated barley by glycogen precipitation followed by cation-exchange chromatography. Preliminary kinetic analysis showed a mixed type mechanism of inhibition with an apparent Ki of 4×10−8M. The inhibitor formed well-defined complexes with barley malt α-amylase 2 and co-purified with the α-amylase by cycloheptaamylose affinity chromatography of glycogen precipitates. The inhibitor was inactive towards α-amylases from sorghum malt, hog pancreas, Aspergillus oryzae, and Bacillus subtilis. The amino acid composition and molecular weight near 21,000 were found to be the same as those of both “band-2 protein” previously identified in preparations of barley malt α-amylase and a specific subtilisin inhibitor from barley. Inhibition experiments confirmed that the malt α-amylase inhibitor is a strong inhibitor of subtilisin Carlsberg. Measurements of α-amylase activity in the presence of equimolar amounts of inhibitor and subtilisin showed that the inhibitor is “double headed”. The inhibitory activity towards α-amylase was lost after treatment of the inhibitor at 70 °C for 15 min. Isoelectric focusing patterns confirmed that the partially heat-labile, basic α-amylase isozymes (pI=6.6) of barley malt are complexes of α-amylase 2 (pI=6.2) and the inhibitor (pI=7.2). Evidence is presented to suggest that proteins with properties similar to those of the barley inhibitor are present in other cereals including wheat and rye. Possible in vivo functions and some practical aspects of the barley inhibitor are discussed.

174 citations


Journal ArticleDOI
TL;DR: In this paper, a theoretical model for the velocity field and the surface profile of bores and hydraulic jumps is developed, where the turbulence is assumed to be concentrated in a wedge that originates at the toe of the front and spreads towards the bottom.
Abstract: A theoretical model for the velocity field and the surface profile of bores and hydraulic jumps is developed. The turbulence is assumed to be concentrated in a wedge that originates at the toe of the front and spreads towards the bottom, and the turbulent closure used is a simplified k-e model allowing for non-equilibrium in the turbulent kinetic energy. The flow equations are satisfied in depth-integrated form (method of weighted residuals), and measured deviations from static pressure are analysed and shown to have a negligible effect on the results. Comparison with measurements shows good agreement, but there is a clear need for further experimental results in the highly turbulent region near the free surface. Some basic mechanisms of the flow are discussed and explained from the theory.

145 citations


Journal ArticleDOI
TL;DR: In this article, the steady state behavior of the external cavity operated laser has been analyzed, taking into account multiple reflections, and the effect of optical feedback is included in the phase and gain conditions by a factor which is shown to have a simple geometrical representation.
Abstract: The steady state behavior of the external cavity operated laser has been analyzed, taking into account multiple reflections. The effect of optical feedback is included in the phase- and gain-conditions by a factor which is shown to have a simple geometrical representation. From this representation it is easily seen how the laser frequency spectrum and the threshold gain depend on external parameters such as distance to the reflection point and the amount of optical feedback. Furthermore, by inserting a variable attenuator in the external cavity and measuring the threshold current versus transmittance we have simultaneously determined the photon lifetime and the absolute amount of optical feedback. For the laser considered we found the photon lifetime \tau_{p} = 1.55 ps.

143 citations


Journal ArticleDOI
TL;DR: The ionic conductivity of Li 3 N crystals doped with various metal ions (magnesium, copper and aluminum) or hydrogen has been investigated in this paper, where a model is proposed for the action of hydrogen whereby the Li-N bonds next to an NH 2-group are weakened thereby facilatating the creation of Li + Frenkel defects and the vacancy migration.


Journal ArticleDOI
TL;DR: In this paper, the electronic structure of the organic conductors bis-tetramethyltetraselenafulvalene (TMTTF) and TMTTF (tetrathiafulvalenes) has been investigated by means of polarized optical and infrared reflectance measurements.
Abstract: The electronic structure of the organic conductors bis-tetramethyltetraselenafulvalene-$X$ [${(\mathrm{TMTSF})}_{2}X$] and bis-tetramethyltetrathiafulvalene-$X$ [${(\mathrm{TMTTF})}_{2}X$] has been investigated by means of polarized optical and infrared reflectance measurements. Analysis of plasma edges in reflectance is used to extract information on transfer integrals. Measurements of infrared reflectance provide information on the energy of charge-transfer processes and on electron-molecular vibration coupling. Far-infrared measurements allow comparison with low-frequency transport properties, and give clues to the transport mechanisms. The main results may be summarized as follows: The ${(\mathrm{TMTSF})}_{2}X$ class of materials has chain-axis transfer integrals of order 0.25 eV at 300 K and 0.28 eV at 30 K. The $b$-axis transfer integral is found to vary from 18 to 24 meV for different $X$. The ${(\mathrm{TMTTF})}_{2}X$ class has a chain-axis transfer integral of the order 0.18-0.20 eV. No $b$-axis plasma edge is observable. The infrared conductivity spectra of the materials consist of a broad electronic band with superimposed vibrational fine structure. The band is centered at 300 ${\mathrm{cm}}^{\ensuremath{-}1}$ in the best ${(\mathrm{TMTSF})}_{2}X$ conductors and at 2200 ${\mathrm{cm}}^{\ensuremath{-}1}$ in ${(\mathrm{TMTTF})}_{2}$P${\mathrm{F}}_{6}$, an organic conductor of moderate conductivity. The electron-molecular vibration coupling constants for TMTSF and TMTTF appear to be qualitatively similar to those of TTF (tetrathiafulvalene). A new feature is the observation of considerable coupling to modes involving methyl groups, suggesting that a sizable charge density is located near these groups. The electronic band in ${(\mathrm{TMTSF})}_{2}$P${\mathrm{F}}_{6}$ sharpens at low temperature, and a pseudogap at 180 ${\mathrm{cm}}^{\ensuremath{-}1}$ is formed at temperatures above the metal-insulator transition. This behavior is discussed in terms of a possible spin-density-wave contribution to the conductivity. The spin-density-wave amplitude is estimated to be $0.02{\ensuremath{\mu}}_{B}$.

Journal ArticleDOI
TL;DR: The results seem to indicate that an alternate location-allocation-savings procedure and a saving-drop procedure are promising, and a newspaper delivery system consisting of 4500 customers is solved.

Journal ArticleDOI
TL;DR: The paper generalizes heuristics for the uncapacitated plant location model to the capacitated case using ADD, DROP, SHIFT, ALA, AlA, and VSM based on elementary ADD and DROP operations.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the assignment of NMR signals in the NMR spectra of mono-and oligosaccharides and their derivatives, and the use of these values in the study of carbohydrates.
Abstract: Publisher Summary This chapter deals with the use of nuclear magnetic resonance (NMR) spectroscopy in the study of mono– and oligosaccharides. The importance of NMR spectroscopy in the study of carbohydrates has increased tremendously. This has occurred primarily because the introduction of pulsed Fourier transform (FT) NMR spectrometers has made the measurement of I3 C NMR spectral parameters easy, which is particularly important for the study of carbohydrates in aqueous solutions. In addition, pulsed NMR instruments have increased the sensitivity of 'H NMR spectra by several orders of magnitude and facilitated the measurement of relaxation times and nuclear Overhauser enhancement (NOE) factors. The chapter discusses the way to assign NMR parameters and the way to use these values in the study of carbohydrates. Moreover, the chapter illustrates that the assignment of the NMR signals is a prerequisite for the application of NMR spectroscopy in structural investigations of carbohydrates. Because assignment techniques have been described in many reviews and monographs, special emphasis is given to the problems associated with the assignment of signals in the NMR spectra of carbohydrates and their derivatives.

Journal ArticleDOI
TL;DR: The results suggest the presence of a second, normally repressed, initiation system for chromosome replication alternative to the ‘normal’ dnaA+ oriC+‐dependent initiation mechanism.
Abstract: The sdrA224 mutants of Escherichia coli K-12, capable of continued DNA replication in the absence of protein synthesis (stable DNA replication), tolerate inactivation of the dnaA gene by insertion of transposon Tn10. Furthermore, oriC, the origin of E. coli chromosome replication, can be deleted from the chromosome of sdrA mutants without loss of viability. The results suggest the presence of a second, normally repressed, initiation system for chromosome replication alternative to the 'normal' dnaA+ oriC+-dependent initiation mechanism.

Journal ArticleDOI
TL;DR: A comprehensive review of flow injection analysis techniques can be found in this article, where a hydrodynamic injector with no moving parts and zero dead volumes is presented, as well as a detailed description of the most recent development within flow injection.

Journal ArticleDOI
TL;DR: It is shown that a graph of large girth and minimum degree at least 3 share many properties with a graphs of large minimum degree, including a contraction containing a large complete graph.

Journal ArticleDOI
TL;DR: A medium, pentachloronitrobenzene-rose bengal-yeast extract-sucrose agar (PRYES), for the isolation of moulds occurring during storage of cereals has been developed and compared with other selective media.
Abstract: A medium, pentachloronitrobenzene-rose bengal-yeast extract-sucrose agar (PRYES), for the isolation of moulds occurring during storage of cereals has been developed and compared with other selective media. The basal medium is yeast extract agar containing 15% sucrose (w/v). In addition to the sucrose content further selective measures include the addition of antibacterial antibiotics chloramphenicol and chlortetracycline (50 mg/l), the fungicides rose bengal (25 mg/l each), and pentachloronitrobenzene (1 g/l) and a low incubation temperature (20 degrees C). Members of the Mucorales were completely inhibited, and fast-growing species of other moulds were slightly inhibited, allowing important storage moulds to develop. The important ochratoxin A and citrinin-producing Penicillium viridicatum group II was indicated by a typical violet brown reverse on PRYES. Producers of xanthomegnin and viomellein (P. viridicatum group I and P. aurantiogriseum) were indicated on PRYES by their yellow reverse and obverse colours. The medium was used for screening 40 samples of barley, and moulds with the characteristic colours were all identified as the species mentioned above.

Journal ArticleDOI
TL;DR: Pulegone and menthol, components of peppermint oil, were investigated in rats and a significant increase in absolute and relative liver weights and vacuolisation of hepatocytes was found and no sign of encephalopathy was observed in rats given menthol.

Journal ArticleDOI
TL;DR: It is shown that the peak factor of radiation is (q 2l+1-1) /(q 2+l-q^{2l}-q2l}) , which is close to 1 as q becomes large.
Abstract: We construct 0, \pm 1 sequences of length (q^{2l+1}-l)/(q-1) , where q=2^{s} , with out-of-phase periodic autocorrelation 0 , and in-phase correlation q^{2l}; SUch that the peak factor of radiation is (q^{2l+1}-1) /(q^{2+l}-q^{2l}) , which is close to 1 as q becomes large

Journal ArticleDOI
TL;DR: In this paper, the relation between binding energy and nonlinearity of a stationary soliton solution for a difference-differential equation of the nonlinear Schrodinger type has been investigated.

Journal ArticleDOI
TL;DR: In this paper, isotopic labelling of the experimental soils was used to determine the presence of cadmium in a selection of agricultural crops, via surface contamination, in Eastern Denmark.

Journal ArticleDOI
TL;DR: In this paper, a non-stoichiometric V6O13±0.2 (VOy) prepared by thermal decomposition of NH4VO3 in N2 atmosphere is investigated cathode material for Li batteries.

Journal ArticleDOI
TL;DR: The results suggest that Antigen 1 may account for more than 10% of the total non-dialysable proteinaceous material in beer, and that about 25% of a major barley albumin present in the brewing materials may be recovered with an almost unmodified protein structure asAntigen 1 of beer.
Abstract: The major antigenic beer macromolecule, Antigen 1, has been isolated from commercial lager beer by succesive use of ultrafiltration, alcohol precipitation, anion exchange, cation exchange and gel filtration chromatography. Amino acid analyses showed a composition identical with that of a major barley albumin, Protein Z, except for a 16% lower content of lysine. Like Protein Z, Antigen 1 showed a molecular weight (MW) near 40,000 in gel filtration and SDS-gel electrophoresis. Unlike Protein Z, Antigen 1 contained 2·5% carbohydrate and was more acidic. When properly standardised, the amount of Antigen 1 in beer could be determined immunoelectrophoretically. Contents ranged from 22 mg/litre in a pale ale (7·7°P; 36% brewers adjunct) to 170mg/litre in a stout (18·8°P). The results suggest that Antigen 1 may account for more than 10% of the total non-dialysable proteinaceous material in beer, and that about 25% of the Protein Z present in the brewing materials may be recovered with an almost unmodified protein structure as Antigen 1 of beer. Apparently, Antigen 1 was not affected by stabilisation of the beer with insoluble PVP or with papaya proteinases.

Journal ArticleDOI
TL;DR: It is demonstrated that substituent groups, such as hydroxymethyl and acetamido groups, on occasions, should be treated in HSEA calculations as freely rotating about their linkage to a pyranose ring.

Journal ArticleDOI
TL;DR: For elastic-plastic cylindrical shells with initial axisymmetric imperfections, a phenomenological plasticity theory was proposed in this article to account for the formation of a vertex on subsequent yield surfaces.
Abstract: For elastic-plastic cylindrical shells with initial axisymmetric imperfections bifurcation into a non-axisymmetric shape is analysed. The shell material is represented by a phenomenological plasticity theory that accounts for the formation of a vertex on subsequent yield surfaces. The influence of various geometric and material parameters is investigated for a wide range of radius-to-thickness ratios. It is shown that for the thicker shells bifurcation generally occurs beyond the maximum axial compressive load. A few analyses for shells with additional non-axisymmetric imperfections show the unstable post-bifurcation behaviour and the sensitivity to imperfections of more general shapes.

Journal ArticleDOI
01 Jun 1983-Ophelia
TL;DR: A positive correlation between ambient algal concentration and algal ingestion rate and gut content for both species in weekly morning samples was found and indicated satiation of the ingestion rates at high algal concentrations.
Abstract: Seasonal and diel variation in rate of algal grazing were estimated from measurements of gut content (plant pigments) and gut turnover in the copepods Centropages hamatus and Pseudocalanus sp. during spring (Januar–May) in the Oresund. Both species exhibited significant diel variation in gut content and ingestion rate at the three depths studied (5, 10 and 22 m), with the highest ingestion rates and gut contents during night. The variation was most pronounced in March, but almost insignificant in April. Since the copepods did not migrate vertically, the observed pattern is due to a variable feeding activity rather than caused by continuous feeding at varying food concentrations. We found a positive correlation between ambient algal concentration and algal ingestion rate and gut content for both species in weekly morning samples. The results indicated satiation of the ingestion rates at high algal concentrations. Maximum algal ingestion rates measured in the field were similar to maximum ingestion...

Journal ArticleDOI
TL;DR: The electrical resistivities of four different cements have been found to exhibit very different age dependencies and these differences cannot be readily explained in terms of their compositions and water/cement ratios.