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  • 1
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    Circuits, systems and signal processing 10 (1991), S. 71-89 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract We consider general input-output systems, which need not be of a feedback type, that are governed by nonlinear operator equations which relate the input, state, and output. Assuming that these equations depend on a parameterA which is allowed to vary in a neighborhood of a “nominal value”A 0 , we study the dependence of the output onA when the input is fixed. Essentially, we call a system insensitive if the output depends continuously onA. Two insensitivity concepts are introduced, and it is shown that certain monotonicity-like conditions ensure insensitivity. Also, several particular cases of the governing equations are studied. As examples, a control system described by a singular system of ordinary differential equations and a nonlinear feedback system are discussed.
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  • 2
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    Circuits, systems and signal processing 10 (1991), S. 153-161 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The relationship between the elements in the vector of any limit cycle due to rounding in ann-order direct-form digital filter is established. Some bounds on the elements in such vectors are also determined. Sufficient conditions for the accessibility of period-r limit cycles due to rounding inn-order digital filters are presented.
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  • 3
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    Circuits, systems and signal processing 10 (1991), S. 327-342 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper analyzes two direction-of-arrival (DOA) estimation algorithms used in the presence of multipath propagation and with very few snapshots. The conditional maximum likelihood (CML) algorithm and the method of direction estimation (MODE) are discussed. The estimates provided by these algorithms are shown to coincide for large number of snapshots or large signal-to-noise ratio. Necessary and sufficient conditions are derived for the algorithms to yield unique estimates. It is shown that their uniqueness conditions coincide with the minimal uniqueness condition on the array, that is independent of the algorithm used (if the array does not satisfy this minimal condition, no DOA estimation method can give unique estimates). Numerical examples are presented to demonstrate the theoretical results.
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  • 4
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    Circuits, systems and signal processing 10 (1991), S. 361-389 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In Part I of this paper we consider a general model of an input-output system governed by nonlinear operator equations that relate the system's input, state, and output, all of which are elements in extended spaces. This model encompasses feedback systems as a special case. Assuming that the equations governing the system depend on a parameterA that is allowed to vary in a neighborhoodN r (A 0) of a nominal valueA 0 in a linear space, we study conditions under which the system is stable for everyA ε Nr(A0), i.e., when the system exhibits robust stability. By stability we essentially mean that the input-output operator is continuous. Depending on the type of continuity of a map between two extended spaces, four concepts of robustness are introduced. The main results, Theorems 1 and 2, furnish sufficient conditions for a system to be robust in the respective sense. Basically, they show that if the nominal system satisfies a certain condition guaranteeing its stability, and the operators appearing in the governing equations depend continuously on the parameterA, then we have robust stability. As examples illustrating the applications of our results we discuss (1) a feedback-feedforward system, in particular the case when the extended space consists of locally square-integrable functions or functions continuous on [0, ∞), and (2) a time-varying dynamical system described by a linear vector differential equation, whose variables are continuous functions on [0, ∞) which decrease exponentially to zero ast → ∞. At the end of the paper some modifications of the presented theory are discussed.
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  • 5
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    Circuits, systems and signal processing 10 (1991), S. 485-511 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Higher-than-second-order statistics-based input/output identification algorithms are proposed for linear and nonlinear system identification. The higher-than-second-order cumulant-based linear identification algorithm is shown to be insensitive to contamination of the input data by a general class of noise including additive Gaussian noise of unknown covariance, unlike its second-order counterpart. The nonlinear identification is at least as optimal as any linear identification scheme. Recursive-least-squares-type algorithms are derived for linear/nonlinear adaptive identification. As applications, the problems of adaptive noise cancellation and time-delay estimation are discussed and simulated. Consistency of the adaptive estimator is shown. Simulations are performed and compared with the second-order design.
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  • 6
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    Circuits, systems and signal processing 10 (1991), S. 53-69 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we study the problem (E) + (BC) + (IC) (see below) which represents a model for integrated circuits. We assume that the distributed parametersr(x) andc(x) are nonconstant, dielectric leakages depend on thex-coordinate as well as the voltage level, while the interconnecting multiport is nonlinear and possibly multivalued.
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  • 7
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    Circuits, systems and signal processing 10 (1991), S. 91-100 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The zero structure at infinity of a linear periodic system can be studied following two different approaches. One is based on the Periodic Invariant Subspace Algorithm and it gives rise to the notion of periodic structure at infinity. The second is based on the representation of a periodic system by means of a family of stationary systems and it allows the definition of a notion of zero structure. In this paper these two approaches are described and analysed in order to compare the structural information contained in the sets of invariants that they define. As a result we have that the zero structure can be derived by the periodic structure.
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  • 8
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    Circuits, systems and signal processing 10 (1991), S. 115-133 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Large-scale dynamical interconnections of systems may not be well defined in the sense of having unique solutions for all inputs. We provide tests that show when the overall system is well defined. In a stochastic interconnected system, there is the additional problem that the composite system may be “stochastically ill defined” in the sense that derivatives of white noise may appear. We provide a test that shows when the interconnected systems is stochastically well defined. It is also demonstrated how to obtain a state-variable representation of the interconnected system, when one exists, on a subspace of the original descriptor-variable space. All of our results are based on “structure algorithms” for singular systems which use stable numerical operations on the original system and interconnection matrices.
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  • 9
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    Circuits, systems and signal processing 10 (1991), S. 175-209 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper extends Morse theory to noncompact manifolds which is important since in many engineering applications the manifolds involved are usually noncompact. To demonstrate the application, generalized Morse theory is used to estimate the number of unstable equilibria on the stability boundary. The engineering significance of the estimation is explained in the paper.
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  • 10
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    Circuits, systems and signal processing 10 (1991), S. 245-259 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper analyzes the convergence properties of an adaptive pseudolinear regression notch filtering algorithm recently proposed in the literature for estimating the frequencies of multiple sine waves from measurements corrupted by possibly colored additive noise. Simple necessary and sufficient conditions for the local convergence of this algorithm to the true frequency values are derived. It is shown that the algorithm has an interesting decoupling property in the sense that satisfaction of the convergence condition by a certain frequency implies local convergence to that frequency no matter whether the other frequencies satisfy or do not satisfy the convergence conditions. However, it is also shown that the algorithm is not generally convergent and, therefore, cannot be recommended for widespread use in applications. Numerical examples are used to illustrate the main points in the theoretical analysis.
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  • 11
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    Circuits, systems and signal processing 10 (1991), S. 285-292 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The goal of this paper is to show that in large samples the variances of the direction-of-arrival (DOA) estimates provided by the element-space MUSIC (i.e., MUSIC applied directly to the sensor output data) are always less than the corresponding variances associated with the beam-space MUSIC (i.e., MUSIC applied to spatially filtered sensor data).
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  • 12
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    Circuits, systems and signal processing 10 (1991), S. 293-326 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper the shape information contents of a morphological vector descriptor, called “pecstrum” (pattern spectrum), are investigated. The pecstrum is then used for aircraft recognition and classification. The pecstrum is a simple vector descriptor which provides information on the way the area of the object is distributed from the fine details to its bulky contents. Although some of its properties have already been reported [3], [4], [14], [23], the use of the pecstrum as a classification tool has not been given appropriate emphasis. At the beginning of the paper some introductory material on mathematical morphology and the pecstrum is presented for the reader who is not familiar with the relevant terminology. Next the shape information which the pecstrum conveys is analyzed and its classification properties are considered. New concepts such as the “pecstral” space and the cumulative pecstral transformation are introduced and explained. The performance of the pecstrum in certain recognition problems is also examined. The concept of “B-shapiness” is redefined and the relation between the pecstrum and the ratio area/perimeter2 is established. The “pseudopecstrum” is then introduced and its information contents and classification properties are compared with those of the conventional pecstrum. The use of pecstrum in estimating object orientation is also addressed. Finally, the recognition and classification capabilities of the pecstrum are tested using a large number of binary objects (airplanes). The performance limit of the pecstrum for efficient object classification, as the size of the objects decreases, is examined and the factors which affect this limit are discussed. The classification results are compared with those obtained using invariant moments.
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  • 13
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    Circuits, systems and signal processing 10 (1991), S. 455-470 
    ISSN: 1531-5878
    Keywords: 34A08 ; 93B07 ; 93B15 ; 93C15 ; 93C50 ; Key words ; Descriptor ; Singular ; Differential-algebraic ; Observability ; Controllability ; Duality ; Structural forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A characterization of observability for linear time-varying descriptor systemsE(t)x′(t)+F(t)x(t)=B(t)u(t), y(t)=C(t)x(t) was recently developed. NeitherE norC were required to have constant rank. This paper defines a dual system, and a type of controllability so that observability of the original system is equivalent to controllability of the dual system. Criteria for observability and controllability are given in terms of arrays of derivatives of the original coefficients. In addition, the duality results of this paper lead to an improvement on a previous fundamental structure result for solvable systems of the formE(t)x′(t)+F(t)x(t)=f(tt).
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  • 14
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    Circuits, systems and signal processing 10 (1991), S. 3-14 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A new suboptimum estimation scheme is proposed for nonlinear discrete dynamic systems with aKth-order memory. These systems are first represented by trellis diagrams, and then states are estimated by the Viterbi algorithm of information theory. The state and observation models of the proposed scheme can be nonlinear functions of the disturbance noise, observation noise, and present and past discrete values of the state, whereas the models of the classical estimation algorithms, such as the extended Kaiman filter, must be linear functions of the disturbance noise and observation noise. States are estimated in blocks, which results in an estimation scheme whose implementation requries a constant memory.
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    Circuits, systems and signal processing 10 (1991), S. 31-51 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In many problems of digital signal processing, it is required to determine a model matching the statistics of a given observation of a generally non-Gaussian random process. Because of the wide range of systems that can be represented by Volterra series and Wiener expansions, the discrete nonlinear second-order Wiener filter (NSWF) driven by white Gaussian noise has been used in this study to match the statistics of a discrete zero-mean stationary non-Gaussian random process. First, we derive the autocorrelation function and show that it does not provide sufficient information necessary for estimating the parameters of the proposed model. Next, we derive the third-order moment sequence and show that it provides additional information that can be used in conjunction with the autocorrelation function to solve the problem. The power spectrum and bispectrum of the discrete NSWF have been also derived.
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    Circuits, systems and signal processing 10 (1991), S. 101-114 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper presents an elementary proof of the well-known Routh-Hurwitz stability criterion. The novelty of the proof is that it requires only elementary geometric considerations in the complex plane. This feature makes it useful for use in undergraduate control system courses.
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    Circuits, systems and signal processing 10 (1991), S. 137-152 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper presents two algorithms for on-line estimation of the optimal gain of the Kalman filter applied to sensor signals when the signal-to-noise ratio is unknown. First-order spectra of a pure signal and colored measurement noise have been assumed. The proposed adaptive Kalman filtering algorithms have been tested for various spectra of the pure signal and noise, and for various signal-to-noise ratios. The effect of the length of an adaptation step and a sampling frequency on the mean square errors of the pure signal estimation has also been examined. Although the test have been performed for stationary signals, the algorithms presented can also be used successfully for time-varying sensor signals when the signal-to-noise ratios vary very slowly in comparison with the length of the adaptation step. The results are helpful for designers who synthesize optimal linear digital filters for sensor signals with first-order spectra and colored measurement noise. The estimation error curves presented enable designers to determine the noise reduction attainable for particular applications of the adaptive Kalman filtering algorithms.
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    Circuits, systems and signal processing 10 (1991), S. 211-219 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper an efficient decoupling Kalman filtering technique is applied to certain Markov chains with finite-dimensional stationary state-transition matrices. For optimal estimates of a Markov chain with ann-dimensional stationary statetransition matrix, the resultant computational algorithm consists ofn-1 simple one-dimensional recursive formulas.
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    Circuits, systems and signal processing 10 (1991), S. 263-284 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this work we analyze the mathematical structure associated with the split algorithms for computing the reflection coefficients for a given real, symmetric, positive-definite Toeplitz matrix. A new form of three-term recurrence relation is derived and computationally efficient alternatives to the Levinson-Durbin, Schur, lattice, and normalized lattice algorithms are obtained. The computational complexity of the new algorithms is the same as those of the split algorithms described in the recent literature. The relationships between the various algorithms are also established. These algorithms also provide further insight into the mathematical properties of the structurally rich Toeplitz matrices.
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    Circuits, systems and signal processing 10 (1991), S. 233-244 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper a fast perturbation algorithm for the design of linear phase FIR digital filters of finite wordlength is presented. The original set of filter coefficients are obtained using the Parks-McClellan algorithm, then a small perturbation is given to these sets of coefficients. The peak deviations corresponding to the rounded set of coefficients obtained from the original and the perturbed sets are compared and the set of coefficients with the lower value of peak deviation is stored as the best set of coefficients. A further perturbation is given to the infinite precision coefficents and these are rounded to the required wordlength. Comparison is made between these rounded sets and the present best set with respect to peak deviation and the better set is stored as the best set of coefficients. This process is repeated for a finite number of times or until the peak deviation is sufficiently low. To obtain the compensating filter coefficients single-frequency filters are used. Mathematical justification for the single-frequency design is given. Important results for a large number of design examples are presented to illustrate the speed and effectiveness of the algorithm.
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    Circuits, systems and signal processing 10 (1991), S. 343-359 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract An existence and uniqueness theory is developed for general nonlinear and nonautonomous differential-algebraic equations (DAEs) by exploiting their underlying differential-geometric structure. A DAE is called regular if there is a unique nonautonomous vector field such that the solutions of the DAE and the solutions of the vector field are in one-to-one correspondence. Sufficient conditions for regularity of a DAE are derived in terms of constrained manifolds. Based on this differential-geometric characterization, existence and uniqueness results are stated for regular DAEs. Furthermore, our notions are compared with techniques frequently used in the literature such as index and solvability. The results are illustrated in detail by means of a simple circuit example.
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    Circuits, systems and signal processing 10 (1991), S. 15-30 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In the study of robust stability, the largest coefficient region of a given stable polynomial that guarantees stability preservation under perturbation of coefficients is to be determined. A general consideration including both Hurwitz and Schur polynomials is treated in this paper. For this purpose, the notion ofperturbation constant is introduced. As a consequence of our results, we also introduce a general Kharitonov-type stability test which is based on testing the stability and perturbation constant of a single polynomial.
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    Circuits, systems and signal processing 10 (1991), S. 163-173 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A few applications of a separable Hartley-like (CAS-CAS) transform in two-dimensional (2-D) signal processing is presented. The applications discussed include (i) the interpolation of signals, (ii) the computation of Hilbert transform, and (iii) the complex cepstrum computation. The computational advantage of the proposed methods over the algorithms using 2-D FFT are discussed.
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    Circuits, systems and signal processing 10 (1991), S. 221-232 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract We introduce an efficient method for computing matrix products of the formY=AXB, whereA andB are sparse and constant. We analyze the complexity of the method, develop quantitative criteria for determining when it can be used effectively, and demonstrate its use in a Kalman filter.
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    Circuits, systems and signal processing 10 (1991), S. 433-441 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we firstly define two new formulations, the symmetric sine structure (SSS) and the symmetric cosine structure (SCS). Then we propose a simple algorithm to realize one-dimensional SCS and SSS with sequence lengths equal to 2 m . We show that a 2m-length discrete Hartley transform can be realized through a 2 m−1-length SCS and a 2 m−1-length SSS, which achieves the same multiplicative complexity as the minimum number of multiplications reported in the literature. However, our approach gives the advantage of requiring less additions compared with conventional approaches. Furthermore, this approach can also be applied to realize a 2m-length real-valued discrete Fourier transform, which requires the lowest number of multiplications compared with conventional real-valued algorithms and needs no complex number operations as found in other real-valued algorithms.
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    Circuits, systems and signal processing 10 (1991), S. 393-431 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In blind equalization a communication channel is adaptively equalized without resorting to the usual training sequence. In this paper we have introduced two new algorithms for blind equalization, which hard limit the equalizer input or the error at the output of the equalizer. These new algorithms are simple to implement and reduce the number of multiplications by approximately one-half. We show by way of simulations that the performance of the algorithm resulting from hardlimiting the error is comparable with the performance of the corresponding algorithm in which the error is not hardlimited. We formulate the new sign-error algorithm as a stochastic minimization of an error functional and demonstrate that the case of zero intersymbol interference corresponds to local minima of this error functional. We also present convergence analysis to predict the output mean square error in both these sign algorithms. Since the algorithms are highly nonlinear we incorporate several simplifying approximations and provide heuristic justifications for the validity of these approximations when the algorithms are operated in a typical practical environment. Computer simulations demonstrate the accuracy of the predicted convergence behavior.
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    Circuits, systems and signal processing 10 (1991), S. 443-454 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper is the second part of [6] which is concerned with the sensitivity of general input-output systems over extended spaces. It is assumed that such systems, which need not be of feedback type, are governed by nonlinear operator equations relating the input, the state, and the output. These equations depend on a parameterA that can vary in a neighborhood of a nominal valueA 0. Essentially, a system is called insensitive if any truncation of its output depends continuously onA provided the input is fixed. The theorems derived provide sufficient conditions for insensitivity. A control system of a feedback-feedforward type and a dynamical system described by a linear vector differential equation on [0, ∞) are discussed as examples.
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    Circuits, systems and signal processing 10 (1991), S. 471-483 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The problem of interpolating a given set of points by means of a squared magnitude rational function of minimal degree is considered. In this way, the resulting interpolating function can be factorized to yield a stable and minimum-phase transference. It is shown that in the polynomial case a nonnegative solution is easily obtained by adding to the standard Hermite interpolation polynomial a suitable term of immediately higher degree. Concerning the general rational case, a computationally efficient procedure, based on a Hermite-type parametrization, is suggested. The positivity requirement may again be met by inserting suitable terms in the numerator and denominator polynomials. An example is worked out to show the practicality of the method.
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    European journal of nutrition 30 (1991), S. 50-55 
    ISSN: 1436-6215
    Keywords: Maillard-Produkte ; LAL ; Bioverfügbarkeit ; Eisen ; Kupfer ; Zink ; Maillard products ; LAL ; bioavailability ; iron ; copper ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Bioavailability of iron, copper, and zinc was investigated in suckling rats. The essential trace elements were given once either with several isolated Maillard products and with LAL, respectively, or with differently heat-treated formula diets. The isolated substances revealed effects on bioavailability of all the elements tested, either on the preresorptive or on the postresorptive level. The formula diets affected only the bioavailability of copper — even when fed for several weeks.
    Notes: Zusammenfassung Es wurde die Bioverfügbarkeit von Eisen, Kupfer und Zink untersucht, wenn diese essentiellen Spurenelemente 1. mit einigen isolierten Maillard-Produkten bzw. LAL, oder 2. mit thermisch unterschiedlich belasteten Testnahrungen einmalig an Säuglingsratten verabreicht wurden. Durch die isolierten Testsubstanzen ließen sich bei allen drei Elementen Effekte auf der präresorptiven und/oder postresorptiven Ebene erzielen. Die Testnahrungen beeinflußten — auch wenn sie fünf Wochen lang verfüttert wurden — nur die Bioverfügbarkeit des Kupfers.
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    European journal of nutrition 30 (1991), S. 73-74 
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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    European journal of nutrition 30 (1991), S. 89-97 
    ISSN: 1436-6215
    Keywords: Vitamin E ; antioxidant ; free radicalmuscle damage ; exercise ; Vitamin E ; Antioxidans ; Muskelschädigung ; Ausdauertraining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Ältere Studien haben gezeigt, daß Vitamin E die sportliche Leistungsfähigkeit bei Schwimmern nicht zu steigern vermag. Trotzdem ist das Vitamin für die Skelettmuskulatur der Sportler wichtig: Als das bedeutendste lipidlösliche Antioxidans in Zellmembranen schützt Vitamin E das Muskelgewebe bei aeroben physischen Belastungen, bei denen der Energiestoffwechsel stark beschleunigt ist, vor übermäßiger Peroxidation von ungesättigten Fettsäuren in Zellmembranen. In verschiedenen Labors führte Ausdauertraining von Versuchstieren zu denselben oxidativen Muskelschädigungen wie Vitamin-E-Mangel: Die Peroxidationsprodukte Pentan und Malondialdehyd waren erhöht, und Muskelenzyme waren vermehrt ins Plasma gelangt. Bei Tieren mit Vitamin-E-Mangel werden die Muskelschäden durch Ausdauertraining verstärkt, während sie durch Vitamin-E-Supplementierung vermindert werden. Präliminäre Studien am Menschen weisen ebenfalls auf eine antioxidative Schutzwirkung von Vitamin E gegen Muskelschädigung hin. Das zeigt sich in reduzierter Bildung von Pentan und in vermindertem Übertritt von Muskelenzymen ins Plasma nach Ausdauertraining. Bei einer Expedition von Bergsteigern ins Himalajagebiet stellten die Autoren ebenfalls eine signifikante Schutzwirkung von Vitamin-E-Supplementierung fest. Diese äußerte sich in einer erhöhten anaeroben Schwelle und in reduzierter Pentankonzentration im Atem bei Belastung.
    Notes: Summary Even though vitamin E may not improve physical achievements in sports competitions, as shown in several swimming experiments, it is important for the health of skeletal muscle: in its role as the major lipid-soluble chainbreaking antioxidant in lipid cell membranes, vitamin E protects muscle tissue in aerobic exercise, in which oxygen metabolism and, consequently, free radical production are greatly accelerated. Animal studies in several laboratories have shown that endurance exercise results in the same type of oxidative muscle damage as does vitamin E deficiency: there is an increase in the peroxidation products pentance and malondialdehyde and in enzymes leaked from muscles to plasma. Oxidative tissue damage in vitamin-Edeficient animals is exacerbated by endurance training and, conversely, it is reduced by high-dose vitamin E supplementation; also, preliminary studies in humans have demonstrated antioxidant protection by high-dose vitamin E supplementation. After endurance exercise leakage of enzymes into the plasma and output of pentane in the breath were significantly reduced. During a high-altitude expedition in the Himalayas, protection was shown to be significantly better in the supplemented group than in the placebo group, as determined by anaerobic threshold and pentane exhalation.
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  • 32
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    European journal of nutrition 30 (1991), S. 118-130 
    ISSN: 1436-6215
    Keywords: Verdaulichkeit ; Passagerate ; Ballaststoffe ; Weizenkleie ; energetischer Nährwert ; digestibility ; rate of passage ; dietary fiber ; wheat bran ; energy value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary An energy metabolism trial was conducted with four sows allocated to each of four levels of wheat bran (7, 14, 21 or 28 g/kg body weight0.75 · day). During 2-week experimental periods half the number of animals received increasing levels of the wheat bran supplementation, the other sows were fed in decreasing order. The basal diet was given constantly at a level of 36 g/kg Bw0.75. Total digestibility of energy was determined by the collection method. For partioning the digestible energy into a prececal and postileal component the diet was supplemented with 0,3 % Cr2O3, and samples of digesta taken by means of a cecum cannula were analyzed for this marker. The rate of passage of food was evaluated by using plastic pellets fed orally as well as inserted into the cecum. During each experimental period a complete energy balance was performed according to the methods of indirect calorimetry. The digestibility and metabolizability of wheat bran energy over the total alimentary tract was 60 % and 57 %, respectively. As a percentage of the total digestible energy, 70 % were found in the prececal site of the digestive tract, and 30 % in the hindgut fermentation. The efficiency of utilization of metabolizable energy (ME) for energy retention was 66.2 %. Utilization of hindgut energy was lower by about a quarter than utilization of energy digested in the small intestine. The mean contents of ME of wheat bran amounted to 10.1 kJ/g dry matter. The ME of the wheat bran fiber (non-starch poly-saccharides) was calculated to be 5 kJ/g. The excretion of short-chain fatty acids in the feces was only 1–2 % of fecal energy. The rate of passage of food decreased from 78 h (basal diet alone) to 52 h with the highest wheat bran supplementation. The prececal retention time was only 20 % of the total rate of passage through the alimentary tract.
    Notes: Zusammenfassung In einem Gesamtstoffwechselversuch erhielten vier Sauen in jeweils zweiwöchiger Periode eine tägliche Zulage von 7, 14, 21 bzw. 28 g Weizenkleie pro kg Lebendmasse0,75. Die Grundration wurde in einer konstanten Menge von 36 g/kg LM0,75 und Tag gefüttert. Zur Messung der präzäkalen Verdaulichkeit wurden dem Futter 0,3 % Cr2O3 zugemischt und Zäkumsaft den kanülierten Tieren entnommen. Die Passagerate des Futters wurde mit Hilfe von peroral und intrazäkal applizierten Kunststoffmarkern erfaßt. In allen Versuchsperioden wurde von jedem Einzeltier eine komplette Energiebilanz erstellt. Die Verdaulichkeit der Energie aus Kleie betrug im gesamten Verdauungstrakt 60 %, die Umsetzbarkeit der Energie 57 %. Davon beliefen sich der präzäkale Anteil auf 70 % und der postileale Anteil auf 30 %. Die energetische Verwertung der umsetzbaren Energie für den Energieansatz betrug 66,2 %. Die postileal abgebaute Kleie wurde um rund ein Viertel schlechter verwertet als die im Dünndarm zur Resorption vorliegende Kleieenergie. Der Gehalt an umsetzbarer Energie in der Kleie errechnete sich auf 10,1 kJ/g Trockenmasse. Der energetische Wert von Ballaststoffen in der Weizenkleie ist auf 5 kJ/g zu beziffern. Die Ausscheidung von kurzkettigen Fettsäuren im Kot war mit 1–2 % der Kotenergie sehr gering. Die Passagezeit des Futters im gesamten Verdauungstrakt verringerte sich von 78 h ohne Kleiezulage auf 52 h in Kleiestufe 28. Die präzäkale Aufenthaltsdauer des Markers betrug nur ein Fünftel der gesamten Passagezeit.
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  • 33
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    European journal of nutrition 30 (1991), S. 138-152 
    ISSN: 1436-6215
    Keywords: Ribonucleosides ; RNAcatabolism ; bovinemilk ; goatmilk ; colostral phase ; lactation period ; minor milkconstituents ; buttersera ; intrinsicindicators ; differentiation ofbutter types ; HPLC ; Ribonucleoside ; RNA-Katabolismus ; Kuhmilch ; Ziegenmilch ; Kolostralphase ; Laktationsperiode ; minore Milchinhaltsstoffe ; Butterseren ; intrinsische Indikatoren ; Differenzierung von Buttersorten ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Ribonucleoside gehören zu den minoren Inhaltsstoffen der Milch und zeigen ein tierartentypisches Ribonucleosidmuster. Neben den unmodifizierten Komponenten Adenosin, Cytidin, Guanosin, Inosin und Uridin wurden modifizierte Verbindungen wie N1-Methyladenosin und N6-Carbamoylthreonyladenosin, die aus dem Transfer RNA-Katabolismus stammen, in Einzel- und Sammelmilchen einer kleinen Herde Deutscher Schwarzbunter nachgewiesen und quantitativ über eine gesamte Laktation bestimmt. Die Verlaufsstudie hat gezeigt, daß die Konzentrationsspiegel dieser minoren Komponenten mit Ausnahme der Kolostralphase über die gesamte Laktationsperiode nur einer geringen Schwankungsbreite unterliegen. Ribonucleosidmuster sind deshalb zur Kennzeichnung von Milchen verschiedener Herkunft und Verarbeitung geeignet. Beispielhaft wurden deshalb Ribonucleoside im Verlaufe des Butterungsprozesses bilanziert und gezeigt, daß diesen minoren Komponenten „finger-print“-Eigenschaften zukommen, die zur Differenzierung der von der Butterverordnung definierten drei Buttersorten geeignet sind.
    Notes: Summary Ribonucleosides are minor milk constituents and show a typical pattern which is assumed to be species-specific. As well as the unmodified components adenosine, cytidine, guanosine, inosine, and uridine, modified compounds such as N1-methyladenosine and N6-carbamoylthreonyladenosine — products of the transfer RNA catabolism — have been identified and quantified in individual and bulk herd (race: German black pied) milk samples throughout a whole lactation period. The results of our longitudinal study have shown that — with the exception of the colostral phase — the levels of these minor constituents vary only slightly throughout lactation. These findings imply that ribonucleosides are useful for characterizing milk of different species and technological treatment. Ribonucleosides were determined and balanced, for example, in the course of the churning process, showing that the pattern of these minor milk constituents is useful as a “fingerprint” that allows differentiation between the three butter types defined in the German Federal Butter Ordinance.
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  • 34
    ISSN: 1436-6215
    Keywords: Eicosapentaensäure ; Docosahexaensäure ; Linolsäure ; Thrombozytenaggregation ; Thromboxan-B- und Prostaglandin-E-Synthese ; eicosapentaenoicacid ; docosahexaenoicacid ; linoleicacid ; plateletaggregation ; thromboxane B andprostaglandin Esynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary In order to estimate the influence of the tested fatty acids on platelet aggregation, synthesis of prostaglandin E and thromboxane B in vitro, platelet rich plasma (PRP) was incubated with the ω-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with linoleic acid as representative of the ω-6 fatty acids, as well as with mixtures of EPA and DHA and all fatty acids, resp., with and without addition of α-tocopherol. For the determinations, platelets were prepared from blood of young adult male volunteers (age 26.6±8 years). Platelet aggregation and synthesis of thromboxane were measured after 30 and 60 min of incubation. Smoking habits were not regarded. The incubation of platelets with DHA and EPA itself, as well as the mixture of fatty acids dominated by ω-3 fatty acids (ω-3/ω-6 = 15/1) caused a significant decrease (p〈0.05) of collagen-induced platelet aggregation. Tocopherol, linoleic acid, and the linoleic-acid-rich mixtures (ω-3/ω-6 = 1/4) caused only a slight inhibition of platelet aggregation. No uniform influence of ω-3 fatty acids could be observed that showed their influence on synthesis of thromboxane to be of importance for the promotion of platelet aggregation. EPA and the mixture of EPA and DHA did decrease thromboxane synthesis significantly (p〈0.05). On the other hand, single incubation with DHA as well as with linoleic acid rich mixtures caused a statistically not significant increase of rate of the synthesis, which did not increase the aggregation. This observation indicates the formation of less effective TXA3. An influence of tocopherol could also not be observed.
    Notes: Zusammenfassung Durch Inkubation plättchenreichen Plasmas (PRP) mit gleichen molaren Mengen an Eicosapentaen-, Docosahexaensäure (EPA, DHA) als wichtigsten Vertretern der ω-3-Fettsäuren (FS) und Linolsäure als Vertreter der ω-6-FS sowie Mischungen aus zwei bzw. den drei Fettsäuren mit und ohne Tocopherolzusatz sollte der Einfluß der getesteten Fettsäuren auf die Thrombozytenaggregation und die Thromboxan-B- bzw. Prostaglandin-E-Synthese untersucht werden. Die Untersuchungen wurden mit Thrombozyten von jungen, erwachsenen Männern (Durchschnittsalter 26,6±8 Jahre) durchgeführt. Die Messung der Aggregation und der Thromboxansynthese erfolgte nach 30- und 60minütiger Inkubation. Das Rauchverhalten wurde nicht berücksichtigt. Bei Inkubation der Thrombozyten mit DHA und EPA jeweils allein sowie mit einer FS-Mischung, in der die ω-3-FS dominierten (ω-3/ω-6 = 15/1), war ein significanter Rückgang (p〈0,05) der kollageninduzierten Thrombozytenaggregation zu beobachten. Tocopherol, Linolsäure und die linolsäurereichen Medien (ω-3/ω-6 = 1/4) inhibierten die Aggregation nur geringfügig. Bei der Thromboxansynthese, die bei der Anregung der Thrombozyten zur Aggregation eine wichtige Rolle spielt, konnte kein einheitlicher Einfluß der ω-3-FS gefunden werden. EPA und die Mischung aus EPA und DHA senkten die TXB-Synthese signifikant (p〈0,05). Die alleinige Inkubation mit DHA sowie die linolsäurereichen Medien führten dagegen zu einem tendenziellen Anstieg der Syntheserate, der jedoch die Aggregation nicht steigerte. Diese Beobachtung weist auf die Bildung des weniger aggregatorisch wirkenden TXA3 hin. Ein Einfluß von Tocopherol war auch hier nicht festzustellen.
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  • 35
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    European journal of nutrition 30 (1991), S. 227-232 
    ISSN: 1436-6215
    Keywords: phosphopeptides ; casein ; heating ; dephosphorylation ; nutritive value of proteins ; Phosphopeptide ; Casein ; Erhitzung ; Dephosphorylierung ; nutritive Proteinqualität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Phosphopeptide können als Carrier für Calcium und Spurenelemente dienen. Im Hinblick auf diese spezifischen nutritiven Effekte wurden die hitzeinduzierten Veränderungen tryptischer Phosphopeptide untersucht, die aus Natrium-Caseinat als Modellsystem freisetzbar waren. Sowohl die Mikrowellen als auch die Backofenerhitzung führte zu einer deutlichen Verringerung an peptidgebundenem Phosphor (Dephosphorylierung) und Abnahme der im tryptischen Hydrolysat gelösten Caseinophosphopeptide. Es wird die Schlußfolgerung gezogen, daß die Hydrolyse von Phosphoseryl- zu Serylresten der vorherrschende Abbauweg zu löslichen Proteolyseprodukten war, während Lysinoalanyl-Casein offensichtlich nur im pH-4.6-unlöslichen Anteil des tryptischen Hydrolysates vorlag.
    Notes: Summary Phosphopeptides derived from casein may function as carriers for calcium and trace elements. In regard to such specific nutritive effects, the heat-induced changes in tryptic phosphopeptides liberated from bovine sodium caseinate as a model system were investigated. Both microwave and oven heating resulted in a marked loss of peptide-bound phosphorous (dephosphorylation) and a decrease of caseinophosphopeptides in the soluble part of the tryptic hydrolysate. It is concluded that hydrolysis of phosphoseryl to seryl residues was the prevailing degradation step to soluble proteolytic products, whereas lysinoalanyl-casein is claimed to be present almost exclusively in the pH 4.6-insoluble part of the tryptic digest.
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  • 36
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    European journal of nutrition 30 (1991), S. 1-3 
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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  • 37
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    European journal of nutrition 30 (1991), S. 18-28 
    ISSN: 1436-6215
    Keywords: Maillardreaktion ; Pathophysiologie ; Aminoguanidin ; postribosomale Modifikation ; Maillard reaction ; pathophysiology ; advanced glucosylation end products ; aminoguanidine ; postribosomal modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary More than 50 years after Maillard's original paper describing the reaction of amino acids with glucose it was found that this reaction also occurs under physiological conditions in the human body. Initially, it was discovered that human hemoglobin contains protein-bound Amadori-products that are increased in diabetic patients with elevated blood glucose levels. Measurements of fructosylated hemoglobin are now widely used as an index of glycemia in diabetes. It was soon recognized that this postribosomal modification is common to other proteins in vivo like albumin, lens crystallins, proteins of the clotting cascade, collagens, lipoproteins, proteins of the cell membrane, and others. This may lead to alterations in structure and function of the respective protein. Later, the realization that long-lived proteins become browned, fluorescent, and insoluble with age, and at an accelerated rate in diabetes, suggested that later stages of the Maillard reaction might proceed in vivo and contribute to some of the pathophysiology associated with both aging and diabetes. Although the contribution of the Maillard products to the development of diabetic late complications is not fully understood, attempts are being made to prevent formation of late Maillard product with aminoguanidine, a drug currently under clinical testing.
    Notes: Zusammenfassung Mehr als 50 Jahre nachdem Maillard (26) die Reaktion von Aminosäuren mit Glucose beschrieben hatte, wurde gefunden, daß diese Reaktion auch unter physiologischen Bedingungen im menschlichen Körper abläuft. Zuerst war entdeckt worden, daß humanes Hämoglobin proteingebundene Amadoriprodukte enthält, die bei Diabetikern mit erhöhten Blutglucosewerten vermehrt waren. Die Bestimmung von fruktosyliertem Hämoglobin ist bereits zur Beurteilung der diabetischen Stoffwechsellage weitverbreitet. Bald darauf wurde nachgewiesen, daß auch andere Proteine wie z.B. Albumin, Linsencrystallin, Proteine der Gerinnungskaskade, Kollagene, Lipoproteine, Zellmembranproteine und andere dieser postribosomalen Modifikation unterliegen, die zu Veränderung von Struktur und Funktion des betreffenden Proteins führen kann. Später wurde erkannt, daß langlebige Proteine altersabhängig braun, fluoreszierend und unlöslich werden. Da diese späten Stadien der Maillardreaktion bei Diabetikern schneller auftreten, wurde vermutet, daß die Maillardreaktion zur Pathophysiologie des Alterns und zur Entstehung der diabetischen Spätschäden beiträgt. Obwohl die ursächliche Beteiligung der Maillardprodukte bei der Entwicklung diabetischer Spätschäden noch nicht verstanden wird, werden bereits klinische Versuche mit dem Medikament Aminoguanidin gemacht, welches die Bildung von späten Maillardprodukten verhindert.
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  • 38
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    European journal of nutrition 30 (1991), S. 65-71 
    ISSN: 1436-6215
    Keywords: Terephthalsäure ; Polyterephthalsäureester ; fettlöslicheVitamine ; terephthalic acid ; polyterephthalic acid ester ; fat-solublevitamin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The effect of terephthalic acid, which is found in foodstuffs as a monomer of fat-soluble vitamins such as vitamin A, D3 and α-tocopherol was examined in model tests of terephthalic acids, and of foils composed of polyterephthalic acid esters. Vitamin A and D3 were stabilized by terephthalic acid (the vitamin content was up to 25 % after adding terephthalic acid, depending on temperature and duration of heating); α-tocopherol was reduced a little faster with terephthalic acid. Heated in the foil the vitamin content was not reduced as much as in the model tests with terephthalic acid.
    Notes: Zusammenfassung Es wurde die Wirkung von Terephthalsäure, die als Monomeres aus Polyterephthalsäureestern in Lebensmittel migriert, auf die fettlöslichen Vitamine A, D3 und α-Tocopherol in Modellversuchen unter Zusatz von Terephthalsäure und unter Verwendung einer Folie aus Polyterephthalsäureestern untersucht. Bei den Vitaminen A und D3 kommt es je nach Erhitzungstemperatur und-zeit zu einer Stabilisierung durch Terephthalsäure (bis zu 25 % höhere Rest-Vitaminmengen nach dem Erhitzen unter Zusatz von Terephthalsäure); bei α-Tocopherol hingegen wird der Abbau durch Terephthalsäure etwas beschleunigt. Bei den Tests in der Folie verläuft der Vitaminabbau langsamer als bei den Modellversuchen unter Zusatz von Terephthalsäure.
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  • 39
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    European journal of nutrition 30 (1991), S. 56-64 
    ISSN: 1436-6215
    Keywords: Analyse ; IQ-Verbindungen ; Erhitzen ; Fleischextrakt ; Maillard-Reaktion ; Mutagenität ; analysis ; IQ-compounds ; heating ; meat extract ; Maillard reaction ; mutagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary During meat processing mutagenic imidazoquinolines and imidazoquinoxalines (“IQ-compounds”) may be formed by Maillard reaction of reducing sugars, amino acids, and creatine/creatinine. IQ-compounds isolated from low-moisture model systems and meat extract by liquid-liquid-distribution were fractionated on a cation exchanger and separated on an RP phase. After acetylation the separated compounds were identified by gas chromatography/mass spectrometry based on their characteristic mass fragment ions. During heating the model systems at 100°C the formation of IQ-compounds begins and greatly increases by further raising the temperature. In different amounts IQ-compounds could also be detected in commercially available meat extracts.
    Notes: Zusammenfassung Bei der Herstellung von Fleischprodukten können sich aus den darin enthaltenen reduzierenden Zuckern, Aminosäuren und Kreatin/Kreatinin im Rahmen einer Maillard-Reaktion Imidazochinoline und Imidazochinoxaline („IQ-Verbindungen“) bilden; diese haben sich als mutagen erwiesen. Die aus wasserarmen Modellsystemen und Fleischextrakt mittels Flüssig-Flüssig-Verteilung isolierten IQ-Verbindungen wurden an einer Kationenaustauschersäule vorfraktioniert und anschließend durch HPLC an einer RP-Phase getrennt. Die Identifizierung der vorher acetylierten Verbindungen erfolgte mittels Gaschromatographie/Massenspektrometrie aufgrund der charakteristischen Massenzahlen ihrer Fragmentionen. Bereits beim Erhitzen der Modellsysteme auf 100°C setzt die Bildung von IQ-Verbindungen ein und nimmt bei weiterer Temperaturerhöhung stark zu. Auch in käuflichem Fleischextrakt können IQ-Verbindungen in unterschiedlichen Mengen nachgewiesen werden.
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  • 40
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    European journal of nutrition 30 (1991), S. 81-88 
    ISSN: 1436-6215
    Keywords: Amino acidscore ; amino acid requirements ; digestibility ; amino acidcontent ; recommendations ; dietaryprotein ; Amino Acid Score ; Aminosäurebedarf ; wahre Verdaulichkeit ; Aminosäuregehalt ; Empfehlungen ; Nahrungsprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Notes: Conclusions The protein digestibility-corrected amino-acid score is considered the most suitable regulatory method for evaluating protein quality of foods and infant formulas. Since this method is based on human amino acid requirements, it is inherently more appropriate than animal assays used for predicting protein quality of foods and the consultation participants therefore recommend that the procedure be adopted as the preferred method of measuring protein values in reference to human nutrition.
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  • 41
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    European journal of nutrition 30 (1991), S. 153-154 
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    Source: Springer Online Journal Archives 1860-2000
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  • 42
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    European journal of nutrition 30 (1991), S. 157-157 
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    Source: Springer Online Journal Archives 1860-2000
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  • 43
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    European journal of nutrition 30 (1991), S. 181-191 
    ISSN: 1436-6215
    Keywords: Nickelfreisetzung ; Edelstahlkochtöpfe ; säurehaltige Lebensmittel ; Nickelallergie ; nickel release ; stainless steel cooking pots ; acid foods ; nickel allergy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary For three items of foods (rhubarb, spinach, sauerkraut) the possible release of nickel (by means of AAS) was analysed, a release which may be caused by a possible corrosive effect of the concerned (oxalic-, milk-, vinegar-) acids (as well as common salt) within a normal domestic food-preparation. For this analysis stainless steel cooking pots of different manufacturers, various types and in a representative selection and quantity were taken into consideration; the detailled analyses were extended so far that clear statistical evaluations were possible. This method complies regulations for accuracy to determine traces of heavy metal. For all three analysed food-stuffs an identical result was reached that no nickel release from the stainless steel cooking pots into the food was found. Differences of the various stainless steel cooking pots with regard to their surfaces' quality or their origin (manufacturers) were not yielded, either. All detected concentrations of nickel are within the reach of the natural nickel content of the analysed food-stuffs and their amount is even much lower than other food's content of nickel. This leads up to the conclusion that the former view of a possible nickel release of stainless steel cooking pots has to be revised because these assumptions were not confirmed in the presented results of this analysis and therefore have to be regarded as not correct.
    Notes: Zusammenfassung Für drei Lebensmittel (Rhabarber, Spinat und Sauerkraut) wurde die mögliche Nickelfreisetzung aus Edelstahlkochtöpfen (mittels AAS) untersucht, die durch eine mögliche korrosive Wirkung der anteiligen (Oxal-, Milch- und Essig-)Säure (sowie Kochsalz) bei haushaltsüblicher Zubereitung verursacht werden kann. In dieser Untersuchung wurden Kochtöpfe verschiedener Hersteller, in unterschiedlicher Ausführung und in repräsentativer Auswahl und Anzahl berücksichtigt. Dabei wurden die Detailuntersuchungen so weit ausgedehnt, daß eindeutige statistische Bewertungen möglich wurden. Die notwendige methodische Absicherung erfolgte nach den für (Schwermetall-)Spurenuntersuchungen üblichen Kriterien. Für die drei untersuchten Lebensmittel konnte übereinstimmend festgestellt werden, daß keine Nickelfreisetzung aus den Kochtöpfen in das darin zubereitete Kochgut feststellbar ist. Es konnten auch keine Unterschiede der verschiedenen Edelstahlkochtöpfe hinsichtlich der Oberflächenqualität oder Herkunft (Hersteller) ermittelt werden. Sämtliche nachgewiesenen Spurenkonzentrationen liegen im Streubereich natürlicher Nickelgehalte der geprüften Lebensmittel und sogar um Zehnerpotenzen niedriger als vergleichbare Nickelgehalte anderer Lebensmittel. Daraus folgt, daß die bisherige Auffassung zur möglichen Nickelfreisetzung bei Edelstahltöpfen revidiert werden sollte, weil entsprechende Annahmen nach den vorgelegten Untersuchungsbefunden nicht bestätigt und als nicht zutreffend angesehen werden müssen.
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  • 44
    ISSN: 1436-6215
    Keywords: pteroylglutamicacid ; brush border membranevesicles ; folate-hydroxyl-antiporter ; diffusion ; Pteroylglutaminsäure ; Bürstensaum-Membranvesikel ; Folat-Hydroxyl-Antiporter ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Der transmembranäre Transport von PteGlu wurde mittels BBMV aus Rattendünndarm untersucht. Der Transport war weder an einen spezifischen Kationengradienten gekoppelt noch durch Veränderungen des Membranpotentials zu beeinflussen. In Gegenwart eines transmembranären pH-Gradienten (pHout 〈 pHin) waren die initialen Transportraten signifikant höher als in Versuchen ohne pH-Gradient. Unter diesen Bedingungen war der Transport zu inhibieren, wenn die BBMV mit DIDS, einem Hemmstoff von Anionenaustauschsystemen, vorbehandelt wurden. Die Aufnahme von PteGlu war nicht erhöht, wenn die BBMV mit HPO 4 2− und Cl− vorbeladen wurden. Unter diesen Bedingungen hatte auch DIDS keinen hemmenden Effekt. Studien zur konzentrationsabhängigen Aufnahme ergaben eine duale Transportcharakteristik in Anwesenheit eines pH-Gradienten und eine lineare Aufnahme in Abwesenheit eines pH-Gradienten. Hieraus ist zu schließen, daß die Aufnahme von PteGlu bei niedrigen Substratkonzentrationen mittels eines PteGlu−/OH−-Antiporters vermittelt wird. Bei höheren Konzentrationen oder in Abwesenheit eines pH-Gradienten erfolgt die Aufnahme hingegen durch nichtionische Diffusion. In einer zusätzlichen Versuchsserie konnte gezeigt werden, daß ein Drittel des Substrates nicht transportiert, sondern an die BBM gebunden wird. Die biologische Bedeutung dieser Bindung bleibt unklar.
    Notes: Summary Intestinal transport of PteGlu was studied using BBMV from rat small intestine. Transport was neither coupled to a specific cation gradient nor was it influenced by variations of the membrane potential. In the presence of a transmembrane pH gradient (pHout 〈 pHin) initial transport was significantly higher compared to studies without pH gradient. Under these conditions transport could be inhibited by pretreating the vesicles with DIDS, an inhibitor of anion exchange systems. Uptake of PteGlu could not be enhanced by preloading the BBMV with HPO 4 2− and Cl− and was not sensitive to DIDS under these conditions. Uptake studies using different concentrations of PteGlu revealed dual transport kinetics in the presence of a pH gradient and linear uptake in its absence. It could be concluded that uptake is mediated by a PteGlu−/OH−-antiporter at low substrate concentrations and occurs by non-ionic diffusion at higher concentrations or in the absence of a pH gradient. In an additional series of experiments it could be shown that about one-third of the substrate is bound to the membrane and is not transported. The biological significance of this binding remains unclear.
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  • 45
    ISSN: 1436-6215
    Keywords: Ausdauersport ; Anthropometrie ; Muskelkompartiment ; Nahrungsaufnahme ; Sportanthropologie ; Sporternährung ; Ultralangstreckenlauf ; endurance sports ; anthropometry ; muscle compartiment ; nutritional intake ; sports anthropology ; sports nutrition ; ultra-long distance running
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The purpose of the study was to examine the changes of the muscle's fat-free compartment and its relation to the corresonding biochemical and nutritional parameters of 42 men and 13 women, the participants of an ultra long-distance run of 1000 km (20 days of daily running 50 km). The muscle-fractions initially increased, decreased in the middle phase, and remained stable for the rest of the run. Significant changes of the fat-free weight were registered from the 11th day on, the LBM decreasing until the middle of the distance; then the lean body mass enlarged. All the muscle-circumferences were reduced with the exception of the thigh, which grew, paralleling the CK/CKMB-concentrations, this phenomenon being due to the high mechanical stress of the lower extremities. The biochemical parameters exhibit a strain-related reaction of adaption within the initial 6 days, the hormones and protein-concentration increasing in the beginning and falling from the third day on, uric acid and CK/CKMB-activity decreasing from the 6th day on. The consecutive parallel reduction of both uric acid, urea, and muscle measurements might be seen as a special endurance-related clearance-mechanism of potential toxicants. The negative relationship between the changes of muscle measurements and the cumulative protein intake and the catabolic constellation of the clinical-chemical values might suggest that the absolute protein intake of 1.7 g/kg body mass should be increased in order to diminish the loss of musculature during an ultra-long distance run.
    Notes: Zusammenfassung Untersuchungsgegenstand sind die Veränderungen des anthropometrisch erfaßten Muskelkompartiments und seiner Beziehungen zu den korrelierenden blutchemischen und ernährungsphysiologischen Kenngrößen bei 42 Teilnehmern und 13 Teilnehmerinnen eines 1000-km-Ultralangstreckenlaufs, der in 20 Tagesetappen von jeweils 50 km zu bewältigen war. Differenziert nach Körperfraktionen folgt auf einen initialen Muskelmasseanstieg eine Abflachung bis zum 12. Tag und bleibt dann stabil. Die aktive Körpersubstanz nimmt zunächst geringfügig ab und steigt nach Laufmitte wieder an. Bei Abnahme sämtlicher korrigierter Muskeldurchmesser zeigte lediglich der Oberschenkeldurchmesser eine anabole Entwicklung, dessen hohe mechanische Belastung seinen Ausdruck im parallel erfolgenden CK- und CKMB-Anstiegen fand. Auch bei den klinischchemischen Parametern vollzieht sich die Laufadaptationsreaktion innerhalb der ersten Tage zwischen 1. und 6. Tag: Testosteron-, Kortisol- und Proteinspiegel steigen bei Laufbeginn an und fallen ab dem 3. Lauftag wieder ab, Harnstoffkonzentration und CK/CKMB-Aktivität erst ab dem 6. Tag. Die konsekutive parallele Reduktion von Harnstoff- und Harnsäurespiegeln und vielen Muskelmaßen ist möglicherweise als Clearance-Mechanismus zur Entfernung potentiell toxischer Substanzen zu verstehen. Aus den negativen Korrelationen zwischen kumulativer Proteinzufuhr und Veränderungen von Muskelmaßen sowie der katabolen Stoffwechsellage kann gefolgert werden, daß die absolute Proteinzufuhr von 1,7 g/kg Körpergewicht absolut zu erhöhen ist, um den Muskelsubstanzverlust unter Ultra-Ausdauerbelastung einzudämmen.
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  • 46
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    European journal of nutrition 30 (1991), S. 318-318 
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  • 47
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    European journal of nutrition 30 (1991), S. 4-17 
    ISSN: 1436-6215
    Keywords: Maillard-Reaktion ; Aromastoffe ; Bräunungsprodukte ; Reduktone ; toxische Verbindungen ; Abbauwege ; Maillard reaction ; aroma compounds ; browning products ; reductones ; toxic substances ; degradation pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Through the Maillard reaction, occurring in food and in the human body, reducing sugars, amino acids and proteins are transformed. Some general and also specific degradation pathways for pentoses, mono- and disaccharides can be defined. The structures of the products are influenced by the type of amine (primary or secondary). During the degradation reactions C-C fissions of the sugars and amino acids (Strecker degradation) can be observed. Some Maillard products are suited as indicator substances to determine the extent of the Maillard reaction.
    Notes: Zusammenfassung Durch die Maillard-Reaktion werden in Lebensmitteln und im menschlichen Körper reduzierende Zucker sowie Aminosäuren und Proteine verändert. Es lassen sich einige allgemeine und auch spezielle Abbauwege für Pentosen, Mono- und Disaccharide formulieren. Die Produktbildung wird u.a. durch die Art des Amins (primär oder sekundär) beeinflußt. Im Verlauf der Abbaureaktionen kann es zu C-C-Spaltungsreaktionen bei den Zuckern und bei Aminosäuren (Streckerabbau) kommen. Einige Maillard-Produkte sind als Indikatorsubstanzen zum Nachweis des Umfangs der Maillard-Reaktion geeignet.
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  • 48
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    European journal of nutrition 30 (1991), S. 29-45 
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    Keywords: advanced glycosylation endproducts (AGE) ; ag(e)ing ; aminoguanidine ; ascorbate ; autoxidation ; biomarker ; browning reaction ; chemical modification of proteins ; diabetes ; glycation ; glycoxidation ; nonenzymatic glycosylation ; oxidation ; Maillard reaction ; Aminoguanidin ; Ascorbat ; Autooxidation ; Biomarker ; Bräunungsreaktion ; chemische Veränderung vonProteinen ; Diabetes ; Glycosylierung ; Glycoxidation ; nichtenzymatische ; Glycosylierung ; Oxidation ; Maillardreaktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Die Maillard- oder Bräunungsreaktion genannten Umsetzungen zwischen reduzierenden Zuckern und Eiweiß führen zur chemischen Zerstörung der Aminosäuren und zum Verlust der Proteinqualität während der Lebensmittelbearbeitung und -lagerung. Der vorliegende Beitrag zeigt Befunde auf, daß die Maillardreaktion auch im Gewebe des Menschen bei der Alterung von Proteinen mit langer biologischer Halbwertszeit auftritt. Die Konzentrationen an den sogenannten Amadori-Produkten, die im Initialstadium der Maillardreaktion aus Glucose und den Proteinen der Augenlinse oder dem Kollagen der Haut entstehen, erwiesen sich als relativ konstant, auch mit zunehmendem Alter. Die Produkte der Glycosylierung und nachfolgenden Oxidation der Proteine, auch Glycoxidationsprodukte genannt, häufen sich dagegen im Alter an, und zwar bei Diabetikern in vermehrtem Maße. Zu diesen Produkten gehören die Aminosäurenderivate N-(carboxymethyl)-lysin (CML), N-(carboxymethyl)-hydroxylysin (CMhL) sowie das fluoreszierende Quervernetzungsprodukt Pentosidin. Während diese Glycoxidationsprodukte in den Körpergeweben nur in Spuren vorkommen, gibt es deutliche Hinweise auf die Anwesenheit weiterer Bräunungsprodukte, deren Charakterisierung jedoch noch aussteht. Es werden Möglichkeiten zur „Entgiftung“ der reaktiven Zwischenprodukte aus der Maillardreaktion sowie zum Abbau extrem gebräunter Proteine diskutiert sowie neuere Möglichkeiten zur therapeutischen Modulierung fortgeschrittener Stadien der Maillardreaktion aufgezeigt.
    Notes: Summary The Maillard or browning reaction between reducing sugars and protein contributes to the chemical deterioration and loss of nutritional value of proteins during food processing and storage. This article presents and discusses evidence that the Maillard reaction is also involved in the chemical aging of long-lived proteins in human tissues. While the concentration of the Amadori adduct of glucose to lens protein and skin collagen is relatively constant with age, products of sequential glycation and oxidation of protein, termed glycoxidation products, accumulate in these long-lived proteins with advancing age and at an accelerated rate in diabetes. Among these products are the chemically modified amino acids, Nɛ-(carboxymethyl)lysine (CML), Nɛ-(carboxymethyl)hydroxylysine (CMhL), and the fluorescent crosslink, pentosidine. While these glycoxidation products are present at only trace levels in tissue proteins, there is strong evidence for the presence of other browning products which remain to be characterized. Mechanisms for detoxifying reactive intermediates in the Maillard reaction and catabolism of extensively browned proteins are also discussed, along with recent approaches for therapeutic modulation of advanced stages of the Maillard reaction.
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  • 49
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    European journal of nutrition 30 (1991), S. 79-80 
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  • 50
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    European journal of nutrition 30 (1991), S. 109-117 
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    Keywords: Guar gum ; serumlipids ; mechanism ; dietarycarbohydrate ; sucrose ; Guar Gum ; Serumlipide ; Mechanismus ; Diätkohlenhydrat ; Saccharose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung In der vorliegenden Untersuchung wurde bei Miniaturschweinen der Effekt von Guar Gum auf die Serumlipide bei gleichzeitiger Gabe von entweder 50,3% Stärke oder 50,3% Saccharose untersucht. Dazu durchliefen 5 adulte hypercholesterolämische Miniaturschweine (Gesamtserumcholesterol 9,0 mmol/l) jeweils nach einer Cross-over-Anordnung 3 Versuchsreihen von Fütterungsexperimenten mit jeweils 8 Wochen Dauer. (Experiment I = Maisstärke plus 15 g Guar; Experiment II = Maisstärke plus 30 g Guar; Experiment III = Saccharose plus 30 g Guar pro Tag.) In Gegenwart von Maisstärke in der Diät hatten weder 15 g noch 30 g Guar Gum einen Einfluß auf die Serum-Cholesterin- oder -Triglyceridspiegel. Die Cholesterinkonzentration in den Lipoproteinfraktionen war während der Experimente I und II ebenfalls nicht signifikant beeinflußt. War hingegen Saccharose in der Diät enthalten, so senkte Guar den Serum-Cholesterinspiegel um ca. 20% (p 〈 0,01) (Experiment III). Bei dieser Diät konnte die Zulage von 30 g Guar pro Tag ebenfalls die Cholesterinkonzentration in den VLDL- und HDL-Fraktionen signifikant (p 〈 0,05) herabsetzen. In Experiment III konnte auch eine tendenzielle Reduktion des Cholesterins in der LDL-Fraktion gemessen werden. Die Untersuchung zeigt, daß Guar Gum einen hypocholesterolämischen Effekt in Gegenwart von Saccharose in der Diät entfaltet, nicht aber bei Stärke als Kohlenhydrat in der Diät.
    Notes: Summary We examined the effect of guar gum on serum lipids if fed together with either 50.3% starch or 50.3% sucrose in a balanced diet to pigs. For this purpose, five adult hypercholesterolemic minipigs (total serum cholesterol 9.0 mmol/l) underwent three consecutive 8-week crossover (control or guar supplementation) feeding experiments (experiment I = cornstarch plus 15 g guar, experiment II = cornstarch plus 30 g guar, experiment III = sucrose plus 30 g guar per day). With the cornstarch-based diet neither 15 g nor 30 g guar gum had an influence on serum total cholesterol or triglyceride levels. Also, the cholesterol concentrations in the lipoprotein fractions did not change significantly during experiments I and II, yet total serum cholesterol concentration was about 20% lower (p 〈 0.01) when guar gum was added to the sucrose diet in experiment III. In the presence of sucrose the supplementation of 30 g guar led to a significant decrease (p 〈 0.05) of the cholesterol concentrations in the very low-density lipoproteins (VLDL) and high-density lipoproteins (HDL). There was also a tendency for decreased cholesterol levels in the low-density lipoproteins (LDL) after adding 30 g guar to the sucrose diet. Thus, the study demonstrates that guar gum exerts a hypocholesterolemic effect in the presence of sucrose in the diet, but not in the case of starch consumption.
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  • 51
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    European journal of nutrition 30 (1991), S. 155-156 
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    Source: Springer Online Journal Archives 1860-2000
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  • 52
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    European journal of nutrition 30 (1991), S. 174-180 
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    Keywords: netvitamin E ; vitamin-Erequirements ; polyunsaturated fatty acids ; foodlabeling ; foodcomposition data ; Netto-Vitamin-E ; Vitamin-E-Bedarf ; Polyensäuren ; Lebensmittelkennzeichnung ; Nährstofftabellen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Der Vitamin-E-Bedarf steht in engem Zusammenhang mit der alimentären Aufnahme von Polyensäuren. Vitamin E schützt diese Polyensäuren vor Peroxidation und wird dabei selbst verbraucht. Zusätzlich hemmen Polyensäuren die Resorption von Vitamin E. So ist es zu verstehen, daß Polyensäuren einen zusätzlichen Vitamin-E-Bedarf erzeugen, der mit 0,6, 0,9, 1,2, 1,5 und 1,8 mg Vitamin E (RRR-alpha-Tocopherol-Äquivalente) je Gramm Dien-, Trien-, Tetraen-, Pentaen- und Hexaensäure angesetzt werden kann. Deshalb ist der Bruttogehalt an Vitamin E in einem Lebensmittel, welches Polyensäuren enthält, nicht zur Beurteilung dieses Lebensmittels als Vitamin-E-Quelle geeignet. Ein geeigneter Maßstab ist vielmehr der Netto-Vitamin-E-Gehalt nach Abzug der für den Schutz der Polyensäuren benötigten Menge von der Gesamtmenge. Bei Berechnung des Netto-Vitamin-E-Gehalts erweisen sich manche als Vitamin-E-Lieferanten angesehenen Lebensmittel in Wirklichkeit als Erzeuger eines Vitamin-E-Defizits, sofern nicht andere Nahrungsbestandteile kompensatorisch das Defizit ausgleichen. Beispiele für den Netto-Vitamin-E-Gehalt einiger Fette und Öle, Fische und Nüsse verdeutlichen die Problematik. Konsequenzen für Nährstofftabellen und für die Lebensmittelkennzeichnung sowie die Problematik der Deckung des Vitamin-E-Bedarfs werden vor diesem Hintergrund diskutiert.
    Notes: Summary The requirement for vitamin E is closely related to the dietary intake of polyunsaturated fatty acids (PUFA). By the protective mechanism to prevent PUFA from being peroxidized, vitamin E is metabolically consumed. In addition, PUFA impair the intestinal absorption of vitamin E. Therefore PUFA generate an additional vitamin E requirement on the order of 0.6, 0.9, 1.2, 1.5, and 1.8 mg vitamin E (RRR-alpha-tocopherol-equivalents), respectively, for 1g of dienoic, trienoic, tetraenoic, pentaenoic, and hexaenoic acid. For this reason, the gross vitamin E content of food containing PUFA does not allow an evaluation of this food as a source of vitamin E. A suitable measure is the net vitamin E content, i.e., gross vitamin E minus the amount needed for PUFA protection. Therefore, some food-stuffs generally considered as vitamin-E sources, as concluded from their gross vitamin E content, cause in reality a vitamin E deficiency if not sufficiently compensated by other vitamin E supplying food constituents. Examples of the net vitamin E content of some fats and oils, fish and nuts are shown. Consequences for food composition data and food labeling and the problem of meeting the vitamin-E requirements are discussed.
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  • 53
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    European journal of nutrition 30 (1991), S. 214-219 
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    Keywords: Salmonellen ; Hähnchen ; Luft-Sprüh-Kühlung ; OSRT-Schnelltest ; Salmonella ; chicken ; air/water-spray system ; Salmonella RapidTest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Chicken cooled by air/water-spray systems were investigated for salmonella by two methods (OSRT-test versus § 35 Food Regulation-Method). The total contamination rate was 95%. Obviously, the air/water-spray system does not allow a significant improvement of hygienic status.
    Notes: Zusammenfassung „Luft-sprühgekühlte“ Hähnchen (n = 131) aus dem Handel wurden vergleichend mittels zweier Verfahren auf das Vorkommen von Salmonellen untersucht (OSRT-Test/§ 35 LMBG-Methode). Die ermittelte Befallsquote lag insgesamt bei 95%. Dies bedeutet, daß die Luft-Sprüh-Kühlung offensichtlich noch keine eindeutige Verbesserung des Hygienestatus ermöglicht.
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  • 54
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    European journal of nutrition 30 (1991), S. 233-237 
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    Keywords: Hydroxyanaloga von Aminosäuren ; H+-Ionen-stimulierter Transport ; Bürstensaum-Membranvesikel ; hydroxy analogues of amino acids ; proton driven transport ; brushborder membran vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Hydroxy analogues of essential amino acids can be used in clinical nutrition to minimize nitrogen intake. In this study intestinal uptake of L-leucine hydroxy analogue into rabbit jejunal brush-border membrane vesicles was investigated. An inward directed H+-gradient was a driving force of uptake (pHoutside = 6.0; pHinside = 7.5) and led to a transient accumulation. The saturable system has a apparent transport constant Kt = 15.4 mM. By trans stimulation experiments it could be shown that both D- and L-stereoisomers of hydroxy analogues of branched chain amino acids as well as L-lactate share with the same H+-driven uptake system.
    Notes: Zusammenfassung Hydroxyanaloga essentieller Aminosäuren können ebenso wie ihre Ketoanaloga zur Minimierung der nutritiven Stickstoffaufnahme verwandt werden. In der vorliegenden Arbeit werden Mechanismen der intestinalen Absorption des L-Hydroxyanalogons von Leucin untersucht. Die Aufnahme dieses Substrates in Bürstensaum-Membranvesikel des jejunalen Kaninchendünndarms wird durch einen nach innen gerichteten Protonengradienten stimuliert (pHaußen 6,0; pHinnen 7,5). Die scheinbare Transportkonstante beträgt 15,4mM. Durch das carriervermittelte Transportsystem werden gleichfalls L- und D-Stereoisomere der anderen Hydroxyanaloga verzweigtkettiger Aminosäuren sowie L-Lactat aufgenommen.
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  • 55
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    European journal of nutrition 30 (1991), S. 289-297 
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    Keywords: Infantnutrition ; breastfeeding ; lactation ; lipids ; fatty acids ; Säuglingsernährung ; Stillen ; Laktation ; Lipide ; Fettsäuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Die Fettsäuren in reifer Muttermilch von 10 Frauen aus einer ländlichen Region Nigerias wurden mit hochauflösender Kapillar-Gaschromatographie untersucht und mit früher erhobenen Ergebnissen aus der Milch von 15 deutschen Frauen verglichen. Die Frauenmilch in Nigeria enthält signifikant höhere Anteile an gesättigten Fettsäuren (Median 54,07 vs. 42,76 Gew.-%). Dieser Unterschied entsteht vorwiegend durch hohe Anteile an Laurin- (C 12:0, 8,34%) und Myristinsäure (C14:0, 9,57%), aber nicht an mittelkettigen Fettsäuren (C8:0, C10:0), wahrscheinlich als Folge einer vermehrten De-novo-Fettsäuresynthese bei den afrikanischen Frauen mit einer kohlenhydratreichen und fettarmen Ernährung. Wesentlich niedrigere Anteile der Ölsäure und der Summe an Monoenfettsäusen (22,82 vs. 37,98%) sowie der trans-isomeren Fettsäuren (1,20 vs. 4,40%) in nigerianischer Frauenmilch dürften aus der niedrigen Nahrungszufuhr an tierischen bzw. partiell gehärteten Fetten resultieren. Obwohl sich in beiden Gruppen ähnliche Gehalte an Linolsäure finden, zeigen die afrikanischen Milchproben höhere Werte für Arachidonsäure und die Summe der n-6-langkettigen Polyenfettsäuren mit 20 und 22 Kohlenstoffatomen (LCP). Der n-6-LCP-Gehalt der Frauenmilch korreliert nicht mit dem Präkursor Linolsäure und scheint nicht von der mütterlichen Nahrungsaufnahme an präformierten LCP aus tierischen Fetten abhängig zu sein. Sehr hohe Werte ergeben sich für n-3-LCP in der Milch der nigerianischen Frauen, bei denen ein relativ großer Anteil der Nahrungsfette durch Seefisch beigetragen wird. Dabei bleibt aber Docosahexaensäure die quantitativ wichtigste n-3-LCP-Fettsäure in der Milch und wird nicht von Eicosapentaensäure verdrängt. Wir folgern, daß der LCP-Gehalt der Frauenmilch nicht allein von der Zusammensetzung der mütterlichen Ernährung abhängt, sondern zusätzlich durch metabolische Prozesse reguliert wird. Wir spekulieren, daß eine solche metabolische Regulation einen Schutzmechanismus für das gestillte Kind darstellen könnte, durch den die kindliche Nahrungszufuhr der physiologisch wichtigen LCP relativ konstant gehalten wird.
    Notes: Summary The fatty acid composition of mature human milk from 10 rural Nigerian women was analyzed by high-resolution capillary gas-liquid chromatography and compared to previously determined results on mature human milk from 15 German mothers. Human milk of the Nigerian group contains significantly higher proportions of saturated fatty acids (median 54.07 vs. 42.76% wt/wt). The difference is primarily caused by high values for lauric (C12:0, 8.34%) and myristic acids (C14:0, 9.57%), but not of medium chain fatty acids (C8:0, C10:0), presumably due to increased de novo fatty acid synthesis in the African women consuming a high carbohydrate and low-fat diet. Markedly lower values of oleic and total cismonounsaturated (22.82 vs. 37.98%) as well as trans-isomeric fatty acids (1.20 vs. 4.40%) in Nigerian milk appear to result from low dietary intakes of animal and partially hydrogenated fats, respectively. Although percentage contribution of linoleic acid (18:2n-6) is similar, arachidonic acid (C20:4n-6) and total n-6 long-chain polyunsaturates with 20 and 22 carbons (n-6 LCP) are higher in the African samples. N-6 LCP secretion with human milk lipids is not correlated to the precursor linoleic acid and seems not to depend on maternal dietary intake of preformed dietary LCP with animal fats. N-3 LCP are very high in milk of the Nigerian women who obtain a large portion of dietary lipids from sea fish, but even then docosahexaenoic (C22:6n-3) and not eicosapentaenoic (C20:5n-3) is the predominant n-3 LCP in milk. We conclude that, in addition to dietary effects, metabolic processes regulate the milk content of n-6 and n-3 LCP. We speculate that such metabolic regulation may protect the breastfed infant by providing a relatively constant supply of the physiologically important LCP.
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  • 56
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    European journal of nutrition 30 (1991), S. 307-312 
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    Keywords: Sojaproteinprodukte ; Gammabestrahlung ; verfügbares Lysin ; Soya protein products ; gamma irradiation ; available lysine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The content in available lysine of soya protein products irradiated in a iin products irradiated in a60Co-gamma cell were investigated. The results indicate that available lysine content and crude protein content at irradiation doses of 1, 3 and 5 kGy were unaffected at the 95% significance level. During 3-month storage the irradiated samples showed no significant (p=0,05) changes of available lysine content. In samples with high content of lecithine, which were irradiated at 1 kGy as well as non-irradiated the content of available lysine was significantly (p=0,05) reduced after 8-month storage; the other products as well as the at 3 and 5 kGy irradiated samples showed no significant decrease. Immediately after irradiation the microflora was significantly (p=0,05) reduced. Under the effect of radiation treatment at 3 and 5 kGy the microflora was reduced to nearly 100% after 3-month storage.
    Notes: Zusammenfassung Es wurde der Gehalt an verfügbarem Lysin in Sojaprotein-produkten nach Gammabestrahlung untersucht. Die Ergebnisse zeigten, daß bei Strahlendosen von 1, 3 und 5 kGy keine signifikanten (p=0,05) Veränderungen des Gehalts an verfügbarem Lysin sowie des Gesamtstickstoffgehalts sowohl unmittelbar nach der Bestrahlung als auch nach dreimonatiger Lagerung auftraten. Mit der Dosis von 1 kGy bestrahlte sowie unbestrahlte lecithinreiche Sojaproteinprodukte zeigten eine signifikante (p=0,05) Abnahme des verfügbaren Lysins nach neunmonatiger Lagerung; bei den anderen Produkten sowie bei den mit 3 bzw. 5 kGy bestrahlten Proben wurde keine signifikante Abnahme festgestellt. Unmittelbar nach der Bestrahlung trat eine signifikante (p=0,05) Reduktion der Mikroflora auf. Nach dreimonatiger Lagerung zeigten die mit Dosen von 3 bzw. 5 kGy bestrahlten Proben eine fast 100%ige Reduktion der Mikroflora.
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  • 57
    ISSN: 1436-6215
    Keywords: Ernährungserhebung ; Lebensmittelverzehr ; Nährstoffaufnahme ; Wochenende ; Werktage ; Dietary survey ; food intake ; nutrient intake ; weekend days ; weekdays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Seven-day food records of the MONICA project Augsburg dietary survey 1984/85 in 899 men aged 45–64 years were used to compare food and nutrient intake of weekdays and weekends. Differences were found in food intake. The mean intake of energy, macronutrients and especially alcohol was higher on weekends, whereas the dietary constituents independent of total energy intake, as percentage supply of energy from macronutrients, did not show huge differences.
    Notes: Zusammenfassung Anhand von 899 Sieben-Tage-Ernährungsprotokollen, die in der Ernährungserhebung 1984/85 des MONICA-Projektes Augsburg an Männern zwischen 45 und 64 Jahren erhoben wurden, wurden Unterschiede im Ernährungsverhalten zwischen Wochenenden und Werktagen untersucht. Es zeigten sich Unterschiede im Lebensmittelverzehr. Die mittlere Zufuhr an Energie und energieliefernden Nährstoffen, vor allem aber an Alkohol, war an Wochenenden deutlich höher als an Werktagen. In von der absoluten Energiezufuhr unabhängigen Variablen, wie z. B. dem prozentualen Anteil der Hauptnährstoffe an der Energiezufuhr, waren die Unterschiede wesentlich geringer.
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  • 58
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    Lasers in medical science 6 (1991), S. 15-21 
    ISSN: 1435-604X
    Keywords: Laser ; Platelets ; Aspirin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser angioplasty involves intravascular laser irradiation which may affect platelets and aggregation. In this study we examined the in vitro effects of different energy doses and modes of CO2 laser irradiation on the platelet number, function and ultrastructure. Since aspirin is used in many patients suffering from coronary artery disease, the consequences of laser irradiation on aspirin-treated platelets were studied as well. We found that CO2 laser irradiation causes a dose-response reduction of the platelet number that is most pronounced with high energy-short duration irradiation, and a dose-response reduction in platelet aggregation which is independent of the mode of irradiation. Pretreatment with aspirin does not change the effects of laser irradiation on platelet number, while aggregation is reduced only at relatively high energy doses. Electron microscopy revealed significant intracellular injury following low energy irradiation, while progressive damage to membranes occurred in a dose-response mode, both in untreated and aspirin-treated platelets. The clinical application of our findings should be done cautiously since important in vivo factors, such as the effect of laser irradiation on the vessel wall and coagulation system, were not studied.
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  • 59
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    Lasers in medical science 6 (1991), S. 53-53 
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  • 60
    ISSN: 1435-604X
    Keywords: Atherosclerosis ; Peripheral arteries ; Laser angioplasty ; Pulsed Nd-YAG laser ; Sapphire tips
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Percutaneous transluminal laser angioplasty with a pulsed Nd-YAG laser (1064 nm wavelength, 100μs pulse duration, up to 0.4 J per pulse, 10 Hz repetition rate) coupled to optical fibres with sapphire tips of 1.8 and 2.2 mm diameter was performed under experimental conditions and then in 30 chronic occlusions of femoral and popliteal arteries in 22 patients. The experimental study in 11 human cadaverous arteries revealed that this laser system was effective in the recanalization of seven femoropopliteal occlusions, but the relative rigidity of the sapphire-tipped contact probe prevented its access to two infrapopliteal vessels. Two perforations occurred after the recanalization of 18 and 15 cm, respectively. Clinically the procedure was successful in 17 out of 25 sessions (68%). The probe formed a primary channel of at least 2.0 mm width which was further dilated by conventional balloon catheter. Ankle/brachial systolic pressure index (ABPI) increased from 0.43±0.13 to 0.79±0.21 after the procedure. In eight cases complications occurred. Two reocclusions were treated by Streptokinase infusion, two procedures were repeated 2 months later, one patient was referred to elective bypass surgery, and three patients were treated conservatively. Six patients were followed-up for more than 6 months. In one patient claudication of 400 m reappeared. ABPI showed a moderate decrease from 0.84±0.20 to 0.69±0.19. These first results are encouraging and it is likely that this method could become an important adjunct to balloon angioplasty.
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  • 61
    ISSN: 1435-604X
    Keywords: Laser angioplasty ; Coronary artery disease ; Nitrogen laser ; Tissue fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract To determine the fluorescence pattern for distinguishing normal (N) from calcified and fibrous plaque (P), fluorescence spectra of cadaveric aorta were measured with a spectrofluorometer. Emission (Em) and excitation (Ex) spectra corrected for instrumental response were obtained from 200 to 1000 nm. Specimens from 50 patients were measured less than 24 h after autopsy and then examined histologically. Spectra from 25 specimens demonstrated that the ratio of fluorescence intensity 460 nm/385 nm with Ex=337 nm provided separation of N from P (1.53±29 vs 0.82±0.25,p〈0.01) and that a ratio of 1.25 correctly identified all N and P. A prospective test of this ratio on an additional 25 specimens yielded a significant difference between N and P (1.70±0.37 vs 0.87±0.23,p〈0.0001) with a value of 1.25 correctly identifying all (10/10) N and 93% (14/15) P. Prospective analysis of previously proposed fluorescence ratios (600 nm/580 nm at Ex=480 nm; 530 nm/550 nm at Ex=459 nm; 448 nm/514 nm and 538 nm/514 nm at Ex=337 nm) all resulted in poor separation of N from P. The ratio of 460 nm/385 nm with Ex=337 nm is superior to previously reported criteria for distinguishing N from P and may be useful for guiding laser angioplasty systems.
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  • 62
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Skin photosensitivity ; Antihistamines
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    Topics: Medicine , Physics , Technology
    Notes: Abstract We have investigated the incidence of cutaneous phototoxicity in 47 patients who received photodynamic therapy between April 1988 and March 1990. Of these, 15 patients received antihistamines as part of a pilot study to evluate their photoprotective role. Patients were followed-up for a minimum of 8 weeks. One out of the fifteen who received antihistamines and 15 out of the 32 patients who did not (p〈0.005), developed cutaneous phototoxicity. On the basis of these results we have initiated a randomized double-blind trial to evaluate the role of antihistamines in haematoporphyrin derivative-induced cutaneous phototoxicity.
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  • 63
    ISSN: 1435-604X
    Keywords: Atherosclerosis ; Alexandrite ; Angioplasty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Pulsed ultra-violet excimer laser radiation is capable of tissue ablation with only minimal thermal injury of adjacent tissue structures. Since difficult fibre optic coupling of energy was observed, alternative Q-switched laser sources capable of ablation of atherosclerotic plaque are under current investigation. To evaluate tissue effects of Alexandrite laser radiation, 160 arterial segments with macroscopic evidence of atherosclerotic disease were treated. The laser light was transmitted via silica based quartz fibres with different diameters. Using the Q-switched Alexandrite laser at the fundamental wavelength (748 nm) with a pulse duration of 300 ns the energy density threshold for tissue ablation was found to be in the range of 63 to 126 J cm−2 using a 300μm fibre. On macroscopic examination only limited thermal and acoustic injury was found in crater adjacent tissue structures. Crater edges were even and did not reveal signs of crater charring or debris in the crater lumen. However, the histological cross-sections revealed thermal injury extending from 100 up to 200μm lateral into adjacent tissue. The crater margins revealed fissuring as a result of shock wave injury. Thermal damage was most evident if irradiation of atherosclerotic tissue was performed in blood.
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  • 64
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    Lasers in medical science 6 (1991), S. 215-215 
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  • 65
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    Lasers in medical science 6 (1991), S. 223-233 
    ISSN: 1435-604X
    Keywords: Angioplasty ; Recanalization ; Laser ; Balloon ; Intravascular ultrasound ; Restenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The current state of clinical laser angioplasty is reviewed. Compared to balloon dilation at the beginning of the past decade, both peripheral and coronary laser angioplasty devices produce better results. Compared to current balloon angioplasty techniques, however, laser angioplasty does not seem to offer improved initial or long term results. Intravascular ultrasound imaging may help to improve laser ablation of atherosclerotic plaque. It remains to be established, however, whether precise debulking of the obstruction will result in a reduced restenosis rate compared to balloon angioplasty.
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  • 66
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    Lasers in medical science 6 (1991), S. 241-254 
    ISSN: 1435-604X
    Keywords: Laser angioplasty ; Photoablation ; Photohydraulic effect ; Fast thermal explosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Besides the coagulation, where the body digests the necrotic tissue and direct evaporation of tissue, the photoablation effect turns out to be very important in tissue removal. In the case of high tissue absorption the process channels in photoablation can either be photochemical (bond breaking) or fast thermal. In the case of transparent media, a plasma formation due to high irradiances and an optical breakdown is necessary for ablation or photodisruption. All the process channels lead to a fast microscale explosion and to Shockwaves. For soft tissue the main process channel is the fast thermal explosion. Assuming that tissue will be disintegrated, if the energy deposited within a single laser pulse is larger than a material specific threshold, the thresholds for the radiant exposure and ablation rates respectively can be calculated. There is a large difference, whether the laser radiation is applied to the tissue surface in noncontact or through a fibre in contact. In contact the ‘fast thermal explosion’ happens in a closed chamber and hence the photohydraulic effect will support the photoablation. The thermally damaged zone in the surrounding tissue depends on the optical penetration depth mainly in cases that the pulse duration is shorter than a critical time given by the heat conductivity. Pulsed lasers can be used ‘non-thermally’ only if the average power is less than a tenth of a watt. With a higher amount of average power a pulsed laser will act comparable to a cw laser.
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  • 67
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    Lasers in medical science 6 (1991), S. 289-296 
    ISSN: 1435-604X
    Keywords: Atherosclerosis ; Dihaematoporphyrin ether/ester, DHE ; Haematoporphyrin derivative, HPD ; Laser angioplasty ; Laser-induced fluorescence ; Plaque
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Selective fluorescence-marking of plaque offers new possibilities in cardiovascular diagnosis and therapy. Angioscopic investigations and spectrometry-assisted laser angioplasty will be simplified and more effective as compared with methods of today. It might help to make laser angioplasty a further promising interventional method to overcome, at least partially, the problems caused by atheromatous or atherosclerotic changes in the cardiovascular system. Fluorescence detection and imaging of markers is usually limited by the intrinsic fluorescence of tissue. Optical differential methods in combination with two-wavelength laser excitation and computer-assisted image processing, however, allow for discrimination of background-related signals and enable plaque detection and imaging at a high contrast. Plaque consists of either fibrotic, lipoid, or calcified depositions and is rather bradytrophic. For that reason in vitro experiments on human specimens post mortem seem to be justified and of clinical evidence. Due to intrinsically different fluorometric properties of plaque and normal vascular tissue imaging of marker-free plaque areas is possible. Additionally the specimens have been incubated with a haematoporphyrin-containing fluorescence marker at concentrations of 10–40μg ml−1 and incubation times of 60 min in order to obtain a corresponding increase in contrast. Lipoid depositions show the highest contrast because of lipophilic properties of the marker, while fibrotic and calcified plaque is slightly less effectively marked. The results, however, so far obtained indicate that fluorescence detection of plaque promises further progress in diagnosis and therapy of cardiovascular diseases.
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  • 68
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    Lasers in medical science 6 (1991), S. 317-321 
    ISSN: 1435-604X
    Keywords: Laser angioplasty ; Coronary artery disease ; PTCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Excimer laser angioplasty is an alternative method for the treatment of obstructive coronary lesions. Initial clinical results demonstrated the safety and feasibility of the procedure. However, efficacy was limited by low catheter flexibility and unreliable energy transmission. Advanced transmission devices were used in 80 interventions in 79 patients. The catheter diameter is 1.3, 1.5 or 1.8 mm, the catheters consist of 20, 30 or 35 quartz fibres (100 μm) respectively. The mean energy density was 55 ±18 mJ mm−2, mean loss of energy transmission was 20%. The pulse width was 60 ns and 115 ns in 40 interventions each. The target vessel was the LAD in 53, the LCX in 6 and the RCA in 21 interventions. Failure of laser angioplasty occurred in 10 patients due to failed guidewire placement (N=6), failed catheter placement (N=3) or impossibility to cross the lesion with the catheter (N=1). Stand-alone laser angioplasty was performed in 43/70 procedures. Additional balloon angioplasty was necessary due to an unsatisfactory result (N=10) or due to complications (N=17) in 27 patients. Vessel occlusion occurred in 18 patients (25%) and could be successfully resolved by balloon dilatation (N=16) or additional laser angioplasty (N=1) in 17 patients. Two early occlusions were found at the 24-h control angiography. The incidence of myocardial infarction and in-hospital death (N=1) was 1.4%. Conclusion: The use of an advanced energy delivery system with trusted energy transmission and higher energy density increased the primary success rate of stand-alone excimer laser angioplasty. However, further improvement of catheter flexibility and reduction of dead space at the catheter tip is necessary to optimize ablation efficacy.
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    Lasers in medical science 6 (1991), S. 339-347 
    ISSN: 1435-604X
    Keywords: Xenon chloride ; Excimer laser ; Coronary angioplasty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Photochemical ablation of coronary artery atheroma using pulsed xenon-chloride excimer laser has, over the past 18 months produced promising results. Worldwide experience amounts to some 2000 cases. In the first 6 months following installation of the Dymer 200+ laser (Advanced Interventional Systems, Irvine, California, USA) at St. Thomas' Hospital, 53 procedures have been performed in 49 patients. Of these, 52.8% were ‘high risk’ (triple vessel disease, unstable angina, LV ejection fraction 〈35%, need to treat sole remaining coronary conduit). Complications were two in hospital deaths (18 and 48 h post-procedure-3.8%); one ELCA related myocardial infarct (1.9%); two haemorrhage requiring transfusion (3.8%); no emergency bypass graft surgery (0%). Current indications for the use of laser include: (1) long-segment diffuse disease; (2) proximal or ostial stenoses in coronary artery or graft; (3) restenosis after balloon angioplasty; (4) total occlusions crossed by a guidewire; (5) severe stenoses crossed by guidewire but not balloon; and (6) bifurcation lesions or stenoses compromising an important side-branch. Potential complications include: arterial perforation; aneurysm formation; peripheral embolization by plaque material; abrupt thrombotic closure; dissection; late sudden occlusion; spasm; and restenosis. Minor problems at the start of the programme involved: modifications to the machine to meet local laser safety requirements; special gases required for the machine; supply and design of fibre optic catheters; guiding catheters; heparin dose; dissection of the coronary artery (major and minor); and selection of patients.
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    Lasers in medical science 6 (1991), S. 371-371 
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    Lasers in medical science 6 (1991), S. 429-435 
    ISSN: 1435-604X
    Keywords: TEA CO2 laser ; Ablation ; Thermal modelling ; Pulse width ; Gelatin ; Absorption coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Ablation of gelatin samples was performed by using a semiconductively preionized TEA CO2 laser, emitting pulses of the lower TEM mode, 100 ns duration, at a repetition rate of 2.4Hz. Ablation rate experiments were performed at a range of fluences from 2J cm−2 to 10J cm−2. Assuming that the absorption coefficient is much larger than the scattering coefficient, experimental data were explained by simple models of ablation. The ablation depth per pulse and the specific absorption depth were calculated from the experimental data.
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  • 72
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tumour ; Haematopor-phyrin derivative ; Photoproduct ; Laser illumination
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    Topics: Medicine , Physics , Technology
    Notes: Abstract Illumination of haematoporphyrin derivative in phosphate-buffered solutions causes the formation of a stable photoproduct with new absorption and fluorescence bands. We report data showing photodynamic activity of the photoproduct. Praestomic tumour OJ-5, carcinosarcoma W-256 (mice) and adenocarcinoma Akatol of colon (rats) have been used. Dynamics of tumour growth, life span of animals and morphological changes of tumour tissues have been the main criteria used to show the photoproduct activity.
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  • 73
    ISSN: 1435-604X
    Keywords: Tissue optics ; Absorption ; Scattering ; Fluence distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper is the second of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. This part begins with a discussion of how the fundamental optical interaction coefficients of tissue may be measured. Both direct methods, in which the coefficients are measured for optically thin samples, and indirect methods, in which the coefficients are inferred from measurements on bulk samples are described. The difficulties inherent in both types of measurement are outlined. Next the wavelength dependence of the scattering and absorption coefficient is discussed, both from a heuristic point of view and by illustration from current literature. We illustrate how the optical spectrum can be divided into regions where the propagation of light is dominated by absorption or scattering effects. Finally we show how the distribution of light fluence in these spectral regions is dramatically different and illustrate the important features of these distributions.
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  • 74
    ISSN: 1435-604X
    Keywords: Laser bronchoscopy ; 1.32μm Nd-YAG laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Endoscopic laser treatment for tracheobronchial malignancy is usually given with the neodymium-YAG laser using the 1.064μm output beam. However, recent experimental work suggests that the 1.32μm output beam of this laser has more desirable tissue effects. We have now treated 55 patients with the 1.32μm Nd-YAG laser (MBB-Medizintechnic) under general anaesthesia, using power settings of 10–20 W and pulse durations of up to 1 s. The indications for treatment were localized airway obstruction in each case. Airway calibre was improved in 46 (84%) patients and this was associated with an improvement in symptoms of cough and breathlessness. Patients with tracheal and carinal obstruction exhibited the most striking clinical improvements with up to four-fold increases in peak expiratory flow. In patients with more peripheral endobronchial obstruction, treatment improved airway calibre less frequently and resulted in a smaller clinical improvement. Of 11 patients with obstruction of a main bronchus and lung collapse, treatment led to partial or complete re-expansion in 10 cases (91%). The 1.32μm wavelength allows treatment to be conducted efficiently and safely but at a considerably lower power than is required for the 1.064μmwavelength. The ability to use low powers has the apparent advantage of generating only negligible quantities of smoke. Our experience with this new laser system demonstrates its considerable potential in the management of tracheobronchial malignancy.
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  • 75
    ISSN: 1435-604X
    Keywords: Autofluorescence ; Fluorescence ; Laser spectroscopy ; Tumour detection ; Tumour diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser-induced autofluorescence spectra from humans were recorded in vivo at three different clinics in a study aimed at investigating the capability of this method to discriminate between malignant tumours and normal surrounding tissues. For the recordings a mobile trolley with the necessary equipment was constructed for use in an examination room or in an operating theatre environment. Laser light was guided through a 600μm optical fibre to the target tissue. The fluorescence from the excited tissue was collected with the same fibre and was fed to an optical multichannel analyser. Two excitation wavelengths were used (337 and 405 nm) in order to optimize the fluorescence signals in two interesting wavelength regions (380–500 and 550–700 nm). Oral and oropharyngeal tumours excited with 405 nm light contained detectable endogenous porphyrins and were in this way discriminated from the normal mucosa. Astrocytoma grade III–IV fluorescence different from that of normal brain tissue, while tumours in the bronchial tree were not detectable using the spectral shape of the pure tissue autofluorescence.
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  • 76
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    Lasers in medical science 6 (1991), S. 451-455 
    ISSN: 1435-604X
    Keywords: Larynx ; Endoscopic microlaryngeal surgery ; CO2 laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The value of functional and reconstructive surgery to the larynx in the treatment of malignant tumours to preserve residual function as far as possible has been clearly demonstrated. A further step in the development of ‘functional surgery’ is classical microsurgery of the larynx which facilitates diagnosis and endoscopic microsurgical treatment of benign tumours. However, recently following the introduction of the carbon dioxide (CO2) laser it has been shown that it is possible to treat also malignant tumours of the larynx by endoscopic microsurgery. An incision made by the photo-thermal CO2 laser scalpel is characterized by the relative absence of bleeding, lack of post-operative oedema, rapid epithelialization without associated infection or cicatrization and this results in optimal post-operative laryngeal function. This paper presents the results of treatment of selected cases of T1 and T2 carcinoma of the glottis treated by CO2 laser excision under microlaryngoscopic control. In this series healing was rapid with minimal hospitalization and without a tracheostomy. Excellent functional results were achieved and the patient was able to return rapidly to his original occupation. It is our opinion that at present this treatment modality represents the optimal treatment for T1 and T2 carcinoma of the glottis.
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    Polymer bulletin 25 (1991), S. 153-159 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Synthesis and cyclopolymerization of 5,6;14,15-dibenzo- 1, 2; 18, 19-diepoxy- 4, 7, 10, 13, 16-pentaoxanonadeca- 5,14-diene (3) was carried out. The polymerization of 3 with tin tetrachloride and boron trifluoride etherate gave the polymers with lower molecular weight. Alternatively, triethylaluminium-water-acetylacetone (Vandenberg catalyst) was effective in preparing polymers of high molecular weight which were soluble in p-cresol and p-chlorophenol. The polymers were essentially composed of cyclic constitutional units corresponding to dibenzo-19-crown-6. The cation-binding ability of the polymer showed the highest selectivity for K+.
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    Polymer bulletin 25 (1991), S. 211-216 
    ISSN: 1436-2449
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polystyrene (PSt) exhibits a new UV absorption band at around 290nm in comparison with ethylbenzene, which is attributed to associative interaction between pendant phenyl groups. Similar absorption bands are also observed for polymers of styrene derivatives. The UV spectra suggest charge-transfer complex formation between the polymeric and monomeric donors with electron-acceptor tetracyanoethylene (TCNE) and the equilibrium constants were estimated to be in the sequence of ethylbenzene 〉 PSt 〉 copolymer of St with methylmethacrylate.
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  • 79
    ISSN: 1436-2449
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary This paper describes the phase transfer catalyzed (PTC) polymerization of 4-bromo-2,6-dimethylphenol (1) in the presence 2,4,6-tri-tert-butylphenol (2) or 4-bromo-2,6-di-tert-butylphenol (4). The polymerization of 1 in the presence of 2 at a 1/2 molar ratio of 3/1 led to poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with $$\overline {\text{M}}$$ n of 13400 g/mol at a yield of 85%. In contrast, the polymerization of 1 in the presence of 4 at 1/4 molar ratios of 5/1 and 10/1 did not produce any methanol insoluble PPO fraction when 4 was added at the beginning of the polymerization. However, PPO with $$\overline {\text{M}}$$ n + 1600 to 2400 g/mol were obtained when 4 was added to the polymerization system after 0.5 h and respectively 2.0 h after the homopolymerization of 1 was started. A radical-anion mechanism is proposed to account for these polymerization results.
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    Polymer bulletin 25 (1991), S. 439-442 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polyoxetane was found to be a good main chain for well-developed smectic liquid crystalline state, when cyano substituted biphenyls were used as mesogenic groups attached through four methylene spacer. With this main chain and spacer, fluorine substituted biphenyl was found to be a novel and good mesogenic group for liquid crystalline state.
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    Polymer bulletin 25 (1991), S. 467-474 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A novel comb-like amphiphilic polymer, poly (2-acrylanidohexadecylsulfonic acid) (PAMC18S), was synthesized by free radical polymerization of the corresponding anphiphilic nonomer in 1,4-dioxane-water mixed solvents. Depending on the ratio of water/dioxane in the solvent, the reaction proceeded by either precipitation polynerization or nicellar polymerization. The nolecular weight of the polymer obtained under similar conditions decreased and subsequently increased with the increase of water content in the mixed solvent. The polyion nature of PAMC16S was confirmed by viscosity data of ethanolic solutions. In addition, the polymer was characterized by solubility, IR, TG and wide angle X-ray diffraction methods.
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    Polymer bulletin 25 (1991), S. 483-490 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A study of the WCl6/(CH3)4Sn/CD2Cl2 initiated polymerization of otrimethylsilylphenylacetylene and 2-hexyne was completed. This study suggests that generated carbenes initiate the polymerization of mono and disubstituted acetylenes. Evidence was provided which clearly shows the formation ofthe initiating [W]=CH2 carbene complex and its immediate disappearance upon addition of both the 2-hexyne and o-trimethylsilylphenylacetylene. Under the reaction conditions used in the present study, no spectroscopic evidence of an initiating or propagating chain end or metallocyclobutene intermediate could be provided.
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    Polymer bulletin 25 (1991), S. A3 
    ISSN: 1436-2449
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    Polymer bulletin 25 (1991), S. 293-297 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A variety of substituted olefins which undergo clean copolymerization with [1.1.1]propellanes 1a,b is presented in this article. For olefins substituted by acceptor groups, strictly alternating 1:1 copolymers are obtained whose structures are proven using high resolution NMR spectroscopy. Evidence for a radical chain mechanism of these copolymerizations is given.
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    Polymer bulletin 25 (1991), S. 335-341 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The large difference in reactivity of L-lactide and ε-caprolactone in ring opening polymerization with stannous octoate, leads to the formation of copolymers with blocky structures. By varying the polymerization temperature, copolymers with different average sequence lengths and molecular weights can be synthesized. It is shown that the average monomer sequence length has a large effect on the thermal and mechanical properties of these copolymers.
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    Polymer bulletin 25 (1991), S. 459-466 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Thin filns of PSt/PMAA and PEO-PSt-PEO block polyners were deposited on a polystyrene substrate by solution adsorption (with or without solvent treatnent), and the filn surfaces were characterized by neans of XPS. Direct solvent-casting of PEO-PSt-PEO from benzene solutions resulted in PSt-rich surfaces, whereas PMAA richer surfaces were obtained for PSt/PMAA filns cast from DMF solutions. Moreover, solvent treatment after casting had profound effect on the filn surface conposition. Treatment with water markedly increased the surface concentration of polar PEO segments. In the case of PSt-PMAA block polymers, the PSt content on the surface increased in the order of water〈 ethanol 〈 cyclohexane 〈 petroleum ether, the last-named giving films with almost pure PSt surface. It is well worth noticing that the bulk conposition had little to do with the surface conposition for both PSt/PMAA and PEO-PSt-PEO block polyners within the conposition range investigated when subsequent solvent treatnent was applied.
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    Polymer bulletin 25 (1991), S. 611-617 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The rheological behavior of the cholesteric side-chain copolysiloxane whose two kinds of mesogenic groups consist of cholesteryl units and biphenyl benzoate units was investigated for three different compositions: 31:69, 35:65, 37:63 (in mol%). On the frequency dependence diagram of G′ for the copolymers at various temperatures, G′ decreases with decreasing frequency. The slope of G′ in a higher frequency region at lower temperatures (110°–130°C) is similar to that in the flow region of amorphous polymer melts. However, the slope of G′ in a lower frequency region at higher temperatures (140°–160°C) is relatively small, and the G′ curves in this region can not be superposed on to a single master curve. This deviation seems to be due to change in stability of the domain structure of the cholesteric phase. Furthermore, on the temperature dependence curve of G′, G′ showed a maximum near T c1 . This maximum of G′ curve seems to be caused by molecular organization of a blue phase.
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    Polymer bulletin 25 (1991), S. 633-640 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary This communication describes the synthesis of two novel CH2=CH-O-headed polyisobutylene (PIB)-based macromers: and The syntheses were worked out by the help of model experiments and subsequently implemented on polymers. The structures were established by detailed1H and13C NMR spectroscopies.
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    Polymer bulletin 25 (1991), S. 669-675 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Cure kinetics of epoxy based on EPON HPT 1071 resin with EPON HPT 1062 curing agent were studied by dynamic differential scanning calorimetry experiment. Kinetic parameters were determined as functions of different epoxy formulations and heating rates. Total heat of cure was independent of heating rate, which was increased with decreasing the concentration of curing agent. The extent of cure at peak is nearly constant and independent of heating rate at a given curing agent concentration. Due to the diffusion controlled cure process, the activation energy of hydroxyl-epoxide reaction (peak 2) is higher than that of the primary amine-epoxide reaction (peak 1). The relationship between peak temperature and heating rate has been also undertaken in this study.
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    Polymer bulletin 25 (1991), S. 451-458 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Oligomers with different aromatic substituents (oligostyrenes, oligo-p-ethylstyrenes, oligo-p-methoxystyrenes and oligo-1-vinylnaphthalenes) were synthesized by living anionic polymerization using sec-butyllithium as initiator. Number average degrees of polymerization were varied between 2 and 16 and narrow homologuedistributions were obtained. In the case of the benzenic types the isolation into pure homologues from dimers to hexamers was carried out by preparative gel permeation chromatography (GPC). In a polymeranalogous heterogeneous catalytic hydrogenation reaction the aromatic compounds were converted into oligomers with saturated cyclic structures, the initial homologue-distributions not being changed. Characterization of all oligomers was performed by GPC and proton nuclear magnetic resonance (1H-NMR). In the case of oligostyrenes and oligo-p-ethylstyrenes the occurrence of the characteristic high field shift of the ortho-protons is observed in dependence of the degree of polymerization. Oligo-1-vinylnaphthalenes show three differently shielded aromatic resonance areas.
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    Polymer bulletin 25 (1991), S. 695-700 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A critical discussion of therigid rod-like andflexible rod-like groups used most frequently in the design of rod-like mesogenic units is presented. Based on the literature data on the potential energy difference and the rotational energy barrier of their extended and kinked configurational isomers and respectively conformers, we suggest a classification inrigid rod-like groups (the rod-like shape of the molecule is rigid although there is free rotation about some of its C-C bonds, like for example oligo-p-phenylenes, diphenyl-acetylenes, etc., and configurational isomers which require a high rotational energy barrier or activation energy like for example, stilbene),semirigid orsemiflexible rod-like groups (conformationally) flexible but of medium rotational energy barrier like for example aromatic esters and amides) andflexible rod-like groups (conformationally flexible groups which require a low rotational energy barrier, i.e., within the same range of values with that of n-butane, like for example: 1,2-diphenylethane and phenyl benzyl ether derivatives). Therefore,rigid, semirigid orsemiflexible, andflexible refer to the ability of the rod-like molecule to change its rod-like shape.
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  • 92
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    Notes: Summary Ethyl 1-cyano-2-(p-methoxyphenyl)cyclopropanecarboxylate (ECMC) with ZnCl2 initiates the free radical polymerization of styrene (St) at 80°C faster than without ZnCl2. A cycloadduct of St and ECMC is detected. The polymer shows a bimodal molecular weight distribution, and a molecular weight increase is observed with conversion. Based on these results, a diradical initiation and propagation mechanism is proposed.
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    Polymer bulletin 25 (1991), S. 559-565 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The content of total chlorine in o-cresol formaldehyde novolac epoxy resin (CNE), the main resin component for encapsulation formulation, affects the reliability of semi-conductor device greatly and it is one of the major criteria used by the electronic industry in measuring the quality of resins. A new process which synthesizes a high purity CNE with less than 300 ppm total chlorine content has been developed. This high purity resin has provided an extended device life under the accelerated stress test condition.
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  • 94
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    Notes: Summary Two novel reactive polymers useful as protecting groups for hydroxyls have been prepared by copolymerization of a silicon containing monomer, 4-[3′-(dimethyl phenyl silyl)-propyl]-styrene, with styrene and divinylbenzene, followed by chemical modification of the resulting insoluble polymer beads. The polymeric reagents containing trialkylsilyl chloride or trialkylsilyl trifluoroacetate moieties are effective for the protection of alcohols and a procedure for their facile regeneration is described.
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    Polymer bulletin 26 (1991), S. 71-77 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two new lactone polymerization catalysts, tin(II)-bis(2,4-pentanedionato-O,O') (Zn(Acac)2) and zinc-bis(2,2-dimethyl-3,5-heptanedionato-O,O') (Zn(DMH)2), together with tin(II)-2-ethylhexanoate (Sn(Oct)2), were used to study the effect of the catalyst in the L-lactide polymerization on the nascent polymer structure. Using Zn(DMH)2 an ultra high crystalline polymer was obtained with a ΔHm of 100 J.g-1. Independent of the catalyst and the crystallinity the structure of the crystalline polymer was a pure α-structure as revealed by WAXS-measurements. SAXS-measurements showed a long period for both the Sn(Oct)2 and the Zn(DMH)2 polymer of about 33 nm., the latter revealing a more complex highly regular structure with up to fourth-order reflections. SEM micrographs showed a fibrillar like structure for the Zn(DMH)2 polymer.
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  • 96
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    Notes: Abstract The miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate (PVC/a-PMMA) blends was investigated by nonradiative energy transfer fluorescence spectroscopy using naphthalene-labeled PVC (PVC-N) with anthracene-labeled PMMA (PMMA-A), or anthracene-labeled PVC (PVC-A) with carbazole-labeled PMMA (PMMA-C). The two sets of results indicate an increase in energy transfer efficiency, corresponding to an increase in blend miscibility, as the PVC concentration increases and, more importantly, demonstrate that the same information about blend miscibility can be obtained using different donor-acceptor chromophore pairs and by changing the polymer to which the donor or the acceptor is attached. The effect of the tacticity of PMMA on its miscibility with PVC was also investigated using PMMA-C and PVC-A labeled polymers. The results confirm that PVC/a-PMMA blends are more miscible than PVC/i-PMMA blends over a large range of compositions.
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    Polymer bulletin 26 (1991), S. 123-130 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Environmental stress corrosion cracking (ESC) behavior of different polyamides (PA) without and with short and glass fiber mat reinforcements was studied in air, water and diluted sulfuric acid and compared. Whereas the neat polymers and their short glass fiber reinforced versions failed by crack growth, the breakdown of the glass mat reinforced polyamide block copolymer (NBC) depended on the corrosion loading history, i.e. on the immersing time. The ESC response of the systems studied was analysed and summarized schematically indicating the effects of matrix structure, type and amount of the reinforcement and environment. Characteristic failure events were also revealed and included in related models. Guide-lines for further material improvements were deduced.
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  • 98
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    Notes: Summary Poly(N-ethyl 3.7-phenothiazinediyl) (1) and poly (N-ethyl 3.7-phenothiazinediyl-co-acetylene) (2) were synthesized by homo- and copolycondensation of 3.7-dibromo N-ethylphenothiazine and 1.2-dibromoethene using a Grignard reaction and NiCl2 or NiCl2.2PPh3 as catalyst. Polymers are soluble in common organic solvents and after doping with iodine have an electrical conductivity of 10−7 −10−6 $$\Omega ^{ - 1} $$ cm−1.
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  • 99
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    Notes: Summary The mechanical properties of amorphous carbon fibres, derived from linear low density polyethylene strongly depend on the fibre diameter, which may be attributed to the presence of a skin/core structure in these fibres. High strength carbon fibres could thus be prepared by using thin precursor filaments, that are obtained by a melt-spinning process, in which the spinline is stretched at an elevated surrounding temperature. Careful carbonization of these precursors gives carbon fibres with a strength of 2.16 GPa, a modulus of 130 GPa and a high strain at break of 3%.
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  • 100
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    Notes: Summary Radical polymerization of methyl methacrylate (MMA) in the presence of methyl α-(bromomethyl) acrylate yielded poly-(MMA) bearing the 2-methoxycarbonylallyl end group through chain reaction involving bimol ecular termination. The molecular weight of the resultant polymer was effectively controlled with a small amount of the bromomethylacrylate added; the chain transfer constant was estimated to be 0.9. The poly (MMA) with the unsaturated end group ( $$\bar M$$ n= 2800 and $$\bar M$$ w/ $$\bar M$$ n = 1.39) was used as a macromonomer for copolymerization with various monomers. The monomer mixture containing styrene and less than 10 mole-% of the macromonomer produced a corresponding copolymer. Copolymers with non-conjugated monomers were also obtained. The macromonomer was less reactive toward poly (MMA) radical than poly (styrene) radical. The radical produced by an addition of poly (styrene) radical to the macromonomer was detected using ESR spectroscopy at room temperature.
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