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  • Articles  (121,499)
  • Springer  (72,064)
  • American Physical Society  (49,435)
  • 1985-1989  (105,210)
  • 1950-1954  (11,739)
  • 1945-1949  (4,550)
  • Physics  (117,946)
  • Electrical Engineering, Measurement and Control Technology  (12,278)
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  • Articles  (121,499)
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  • 1
    Electronic Resource
    Electronic Resource
    Design of FIR filters with reduced computations (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 17-23 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The performance of a symmetric nonrecursive filter can be improved by multiple use of the same filter. The method is based on an Amplitude Change Function (ACF). An approach to the design of nonrecursive filters using an ACF is discussed in this paper. The prototype filter chosen is a Recursive Running Sum (RRS) filter which does not require any multipliers for its implementation. The required filter specifications are met by multiple use of the RRS filters. The overall filter requires a much smaller number of multiplications and adders than the one designed using the conventional method. It is shown that this method provides reduced noise due to coefficient quantization and product quantization compared with the conventional design technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598743
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  • 2
    Electronic Resource
    Electronic Resource
    Statistical analysis of two nonlinear least-squares estimators of sine-wave parameters in the colored-noise case (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 3-15 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper establishes the large-sample accuracy properties of two nonlinear least-squares estimators (NLSE) of sine-wave parameters: the basic NLSE, which ignores the possible correlation of the noise, and the optimal NLSE, which, besides the sine-wave parameters, also estimates the noise correlation (appropriately parametrized). It is shown that these two NLS estimators have thesame accuracy in large samples. This result provides complete justification for preferring the computationally less expensive basic NLSE over the “optimal” NLSE. Both estimators are shown to achieve the Cramér-Rao Bound (CRB) as the sample size increases. A simple explicit expression for the CRB matrix is provided, which should be useful in studying the performance of sine-wave parameter estimators designed to work in the colored-noise case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598742
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of two-dimensional losslessm-Ports with prescribed scattering matrix (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 97-119 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Multidimensional lossless networks are of special interest for use as reference structures for multidimensional wave digital filters [l]–[3]. The starting point of the presented synthesis procedure for two-dimensional representatives of the networks mentioned is a scattering matrix description of the desired multiport. This given matrix is assumed to have those properties which have turned out to be necessary [9], [10] for any scattering matrix of a multidimensional lossless network. The method presented for the synthesis of 2-D reactancem-ports is based mainly on known properties of block-companion matrices and the factorization of a univariable rational matrix which is discrete para-Hermitian and nonnegative definite on the unit circle. The resulting network always contains only a minimal number of frequency-dependent building elements. No restrictions are made concerning the coefficients of the rational entries of the scattering matrix; they may be either real or complex, so as to include even complex networks which are of special interest for multi-dimensional wave digital filters [3].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598747
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  • 4
    Electronic Resource
    Electronic Resource
    Systems which possessg- andh- Representations (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 145-162 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Examples are given concerning the range of applicability of recent representation results that provide a means of studying the input-output properties of nonlinear systems in terms of the familiar impulse-response concept, and which extend the concept of integral transformation to nonlinear maps. We show that such representations, which we call “g-” and “h-representations,” exist for important classes of systems governed by nonlinear integral equations. In particular, it is proved that a large class of maps that have Volterra series representations also have these representations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599935
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  • 5
    Electronic Resource
    Electronic Resource
    The pseudorandom sequence of arrays (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 133-144 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Pseudorandom (or maximal length) sequences and arrays have been known for a long time, and have been reported by several authors. Pseudorandom volumes have also been mentioned. This paper presents a different type of sequence of arrays in which the arrays share many properties with the pseudorandom arrays of the literature, and the sequence (or group) of arrays has many properties in common with the pseudorandom sequences. It is proposed that this set of arrays be called a “pseudorandom sequence of arrays,” or PRSAs. Some interesting properties of the PRSA as well as its practical (hardware) implementation have been mentioned. It has also been shown that our result is a special case of the generalN(3)/D(3) case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599934
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  • 6
    Electronic Resource
    Electronic Resource
    A recursive parameter estimator yielding exponential convergence under sufficient excitation (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 207-228 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract For linear time-invariant discrete-time systems, an exponentially convergent recursive parameter identification scheme is derived requiring only that the regression vector be sufficiently exciting, that is the sum of the outer products of the regression vector is eventually positive definite. The algorithm produces a parameter estimate that converges to the batch-form (nonrecursive) least-squares estimate without requiring a persistent excitation. The rate of convergence can be selected as a design parameter. If the regression vector is persistently exciting, it is shown that a forgetting factor can be added to the formulation in such a way that the magnitude of the forgetting factor and the rate of exponential convergence can be set separately.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599938
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  • 7
    Electronic Resource
    Electronic Resource
    Image modeling and restoration: A new approach (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 229-229 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599939
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  • 8
    Electronic Resource
    Electronic Resource
    Some circuits and systems applications of semistate theory (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 235-260 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The semistate theory of circuits and systems is reviewed with regard to its applications. Among these latter discussed are electronic circuit design and analysis, hysteresis, knot generation, neural networks, and constrained robot characterizations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598413
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  • 9
    Electronic Resource
    Electronic Resource
    On Hautus-type conditions for controllability of implicit linear discrete-time systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 289-298 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Four notions of controllability for general (i.e., possibly nonregular) implicit linear discrete-time systems are considered. Relationships between them are studied. A Hautus-type characterization of all of these notions is also given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598416
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  • 10
    Electronic Resource
    Electronic Resource
    Strategies for finite-time control in singular systems in open- and closed-loop configurations (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 299-312 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A new concept of system equivalence which allows the establishment of a formal relation between singular and regular systems has been introduced. By applying this concept, an open-loop strategy for finite-time control of a given solvable singular system, which is simple for both computation and implementation, is developed. A strategy for finite-time output feedback control is considered for a continuous singular system. It is shown that provided the system is observable, a desired polynomial command for finite-time control can be determined from a finite sequence of output measurements sampled at discrete instants of time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598417
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  • 11
    Electronic Resource
    Electronic Resource
    Reachability, observability, and minimality for shift-invariant two-point boundary-value descriptor systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 313-340 
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    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 system-theoretic properties of two related classes of shift-invariant two-point boundary-value descriptor systems (TPBVDSs), namelydisplacement systems for which Green's function is shift-invariant, andstationary systems for which the input-output map is stationary. For such systems it is possible to obtain detailed characterizations of the properties of weak reachability and observability introduced in [16] and of minimality as well. An important difference, that has also been noted before in a different context [9], is that there is a certain level of nonuniqueness in minimal realizations. Another property that is studied in this paper is that of extendibility, i.e., the concept of considering a TPBVDS as being defined on a sequence of intervals of increasing length. Necessary and sufficient conditions for extendibility are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598418
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  • 12
    Electronic Resource
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    Call for papers (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. I 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598422
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  • 13
    Electronic Resource
    Electronic Resource
    Signal scaling in cascade digital filters (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 421-426 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Scaling of filter variables is central to fixed-point implementation of digital filters. A simple method of scaling based on scaling constants of individual sections of a cascade digital filter is presented. The proposed method saves much computational labor in the implementation of higher-order digital filters. Maximal amplitude expressions of second-order filter transfer functions are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599763
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  • 14
    Electronic Resource
    Electronic Resource
    Zero-input limit cycles and stability in second-order fixed-point digital filters with two magnitude truncation quantizers (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 427-433 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper is concerned with the stability analysis of second-order direct-form digital filters with two magnitude truncation quantizers. Zero-input stability is proved for the parameter regions where no conclusion can be drawn using the methods previously suggested in the literature. The areas of the parameter plane in which only limit cycles of period 1 or 2 exist, are determined and related to the cycle amplitudes. Finally, a transition graph is suggested to study the convergence patterns of the filter output.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599764
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  • 15
    Electronic Resource
    Electronic Resource
    Analysis of a digital PLL Markov model (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 467-486 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The work of digital PLL is analysed. For this analysis a Markov model is used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599768
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  • 16
    Electronic Resource
    Electronic Resource
    One-multiplier adaptive lattice algorithm for recursive filters (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 455-466 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The formulation of one-multiplier lattice structures of the Gray-Markel type forinfinite impulse response filters is reviewed. Several special cases of this formulation — including the well-known Gray-Markel normalized lattice—are presented as scaled polynomial versions of the two-multiplier lattice. A new adaptive algorithm is presented for updating the parameters of one-multiplier lattice structured recursive filters. The LMS-based algorithm requires fewer computations than earlier reported algorithms [1]–[4].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599767
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  • 17
    Electronic Resource
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    Computation of minimal-order realizations of generalized state-space systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 49-70 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we consider the problem of obtaining minimal-order representations of generalized state-space systems described by equations of the formE x(t)=A x(t)+B u(t),y(t)=C x(t)+D u(t) withE singular and det(sE−A)≠0. The underlying principle is that of removal of impulsive and exponential uncontrollable and unobservable modes. When this is followed by the removal of the remaining impulsive modes, we get a minimal-order generalized or standard state-space representation. Simple reduction procedures and numerical algorithms based on these principles are developed and illustrated by means of two numerical examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598745
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  • 18
    Electronic Resource
    Electronic Resource
    Estimation for boundary-value descriptor systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 25-48 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we consider models for noncausal processes consisting of discrete-time descriptor dynamics and boundary conditions on the values of the process at the two ends of the interval on which the process is defined. We discuss the general solution and well-posedness of systems of this type and then apply the method of complementary processes to obtain a specification of the optimal smoother in terms of a boundary-value descriptor Hamiltonian system. We then study the implementation of the optimal smoother. Motivated by the Hamiltonian diagonalization results for nondescriptor systems, we show how the descriptor Hamiltonian dynamics can be transformed to two lower-order systems by the use of transformation matrices involving the solution of two generalized Riccati equations. We present several examples illustrating our results and the nature of the smoothing solution and also present equations for covariance analysis of boundary-value descriptor processes including the smoothing error.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598744
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  • 19
    Electronic Resource
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    Call for papers (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. I 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598748
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  • 20
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    On the reducibility of centrosymmetric matrices — Applications in engineering problems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 71-96 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The structure inherent to the centrosymmetric matrices is exploited to obtain factorization results leading to significant computational savings in many engineering applications. Several interesting properties of the matrices are discussed with a view toward algorithm computational complexity. It is shown that the multiplicative complexity involved in the process of principal component (eigen-value/eigenvector) extraction, and in the evaluation of the determinant and inverse of such matrices, can be reduced by nearly 75% by employing the results presented here. The theory presented hereunifies andgeneralizes previous computationally efficient results onseveral specialized generalized centrosymmetric matrices; for example, the class of symmetric centrosymmetric (or doubly symmetric) matrices is shown to be a special case of the class of centrosymmetric matrices, and since the results obtained here are applicable over the field of complex numbers, the factorization results available for centrosymmetric matrices are readilyextended to the complex field. The centrosymmetric matrices play an important role in a number of areas such as pattern recognition, antenna theory, mechanical and electrical systems, and quantum physics. Specific examples of pattern recognition feature selection, a uniform linear antenna array, vibration in structures, and the quantummechanical oscillator are discussed to demonstrate that the theory developed here has a wide range of applications. In addition, certain specialized cases of the centrosymmetric matrices have, in the past, proved their indisputable usefulness in the areas of communication theory, digital filters, linear systems, linear prediction, and speech analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598746
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  • 21
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    Stability tests for singular cases of discrete systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 123-132 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The well-known Jury and Blanchard's stability test for discrete systems is with an array of (2n−3) rows of elements. Raible simplified Jury and Blanchard's array to (n+1) rows by introducing an additional element at the end of each row. Chen and Chan recently derived a Liapunov function through Schwarz' transform to prove the criterion directly and to produce a very compact form. The purpose of this paper is to explore the various singular cases by using the newly established Chen-Chan criterion. Some existing methods for studying singular cases are re-examined under the light shed by Chen and Chan. A by-product is to define and to determine the relative stability of discrete systems.
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    URL: http://dx.doi.org/10.1007/BF01599933
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  • 22
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    Investigation of the mathematical properties of a new negative resistance oscillator model (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 187-205 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A new negative resistance oscillator model was proposed by Walker and Connelly. We investigate the mathematical properties of the associated nonlinear differential equation for a single-mode LCR network oscillator. In particular, we prove that under suitable conditions, small-amplitude stable limit-cycle oscillations can occur. The method of harmonic balance is used to calculate an analytic approximation to the limit-cycle parameters. Also, the general properties of trajectories in phase-space are presented. These predictions are compared with the results obtained by numerical integration of the differential equation.
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    URL: http://dx.doi.org/10.1007/BF01599937
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  • 23
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    Block decomposition structures for the fast modular implementation of two-dimensional digital filters (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 163-185 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A general structure is presented for the block realization of two-dimensional infinite impulse response digital filters, which is based on the two-dimensional matrix convolution equations and the decomposition of their associated transfer function matrices. The proposed decomposition may be considered as an extension of the scalar decomposition technique, which has already been used for the realization of two-dimensional digital filters associated with two-variable polynomials. The decomposition structure is considered in two different forms, which correspond to the direct forms I and II. It is shown that if a given two-dimensional single-input, single-output filter is realizable, then realizable block decomposition structures may be always selected. The proposed approach is general and applies without any restriction for the block implementation of any two-dimensional filter. The resulting structures are characterized by high inherent parallelism, modularity, regularity, reconfigurability, local interconnections, and very high sampling and throughput rates. Thus they are well suited for VLSI implementation and implementation via multiprocessor systems and array processors, such as systolic and wavefront arrays.
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    URL: http://dx.doi.org/10.1007/BF01599936
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  • 24
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    Call for papers (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. I 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599940
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  • 25
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    Editorial (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 231-231 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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    URL: http://dx.doi.org/10.1007/BF01598411
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  • 26
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    Editorial: A new vocabulary for system theory? (1989)
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    Circuits, systems and signal processing 8 (1989), S. 233-234 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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    URL: http://dx.doi.org/10.1007/BF01598412
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  • 27
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    Distributional convergence of BDF approximations to solutions of descriptor systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 261-265 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract It has been observed that the backward differentiation approximation to the solutions ofEx′+Fx =f can fail to converge even pointwise in an initial boundary layer. This paper shows that the approximations converge in a distributional sense even if the exact solution is also distributional.
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    URL: http://dx.doi.org/10.1007/BF01598414
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  • 28
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    Stability analysis of singular systems (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 267-287 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper deals with a refined qualitative analysis of motions of a broad class of continuous time-varying nonlinear singular differential systems. These systems consist of a finite number of first-order differential equations that cannot be set into the normal form. Some novel qualitative concepts, convenient for the description of solutions of singular systems, are introduced and analyzed. These concepts involve some inherent properties of singular systems. General sufficient conditions for these concepts are derived in terms of the existence of a suitable Lyapunov function. Also, for the subclass of singular systems considered, the construction of a Lyapunov function candidate that can be effectively applied in the analysis is proposed. The results obtained generalize some known results in stability theory.
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    URL: http://dx.doi.org/10.1007/BF01598415
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  • 29
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    Fundamental matrix of discrete singular systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 341-355 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The objective of this paper is to make clear the fundamental importance of thefundamental matrix ϕ k in the analysis of linear discrete-time singular systems. We relateϕ k to the coefficientsR k of the adjoint matrix (zE-A)−1, find an autoregressive recursion for theϕ k , and give the solution of the singular semistate equation in terms ofϕ k . Also discussed are thesemistatetransition matrix and the singular systemTschirnhausen polynomials. We close by giving a stable numerical technique for the computation of the sequenceϕ k that is based on first taking the pencilzE-A to triangular form.
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    URL: http://dx.doi.org/10.1007/BF01598419
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  • 30
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    Infinite elementary divisors of polynomial matrices and impulsive solutions of linear homogeneous matrix differential equations (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 357-373 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Impulsive solutions of linear homogeneous matrix differential equations are re-examined in the light of the theory of Jordan chains that correspond to infinite elementary divisors of the associated polynomial matrix. Infinite elementary divisors of general polynomial matrices are defined and their relation to the pole-zero structure of polynomial matrices at infinity is examined. It is shown that impulsive solutions are due to Jordan chains of a “dual” polynomial matrix that correspond to infinite elementary divisors that are associated with the orders of “zeros at infinity” of the original matrix.
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    Geometric theory and feedback invariants of generalized linear systems: A matrix pencil approach (1989)
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    Circuits, systems and signal processing 8 (1989), S. 375-397 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Generalized linear systems are classified according to their algebraic structure and their regularizability and normalizability properties under generalized state feedback are investigated. New feedback invariants are introduced in terms of the input-space restriction pencil and the Plücker matrix of the system. It is shown that the classification of subspaces of the state space of generalized linear systems is reduced to an equivalent problem of classifying the subspacesV of the domain of an ordered pair (F, G), F, Gεℝm×n. The set of strict equivalence invariants of the restriction pencil (F, G)/V provides a complete, basis-free algebraic characterization and leads to the definition of notions of geometric invariance. The key geometric notions that emerge are those of (F, G)-, (G, F)-, complete-(F, G)-, partitioned(F, G)-, cyclic-, and semicyclic-invariant subspaces. A complete set of geometric algorithms leading to the computation of the above families is also given. The above families of invariant subspaces are characterized in terms of the invariants of (F, G)/V, and this provides the links with their dynamic characterization. These results provide an “open-loop” or “feedback-free” unifying treatment of spaces of generalized systems, which for the case of proper systems is reduced to the standard geometric theory results.
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    Fast prime factor decomposition algorithms for a family of discrete trigonometric transforms (1989)
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    Circuits, systems and signal processing 8 (1989), S. 401-419 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper develops a set of fast prime factor decomposition algorithms (PFDAs) for a family of discrete trigonometric transforms of sizeN, whereN is a product of two relatively prime integers. Relevant equations for the PFDAs are derived. Computational procedures are presented followed by a specific example forN= 12. The input and output index mappings necessary for the algorithm are obtained and the computational complexity is briefly outlined.
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    The difference between regularity and irregularity in singular systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 435-444 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In the studies of singular systems regularity is often presumed although it may not be satisfied in some real cases. Therefore, natural questions are: What is the difference between regularity and irregularity? How far can we go from regularity to irregularity in the studies of singular systems? This paper partially answers these questions. The results show that the concepts of reachability, controllability, and observability for regular systems can be easily extended to irregular cases. There is minor difference between regular and irregular singular systems. Thus the assumption of regularity is reasonable.
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    Modified design of high-order 1-D all-pass recursive digital filters (1989)
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    Circuits, systems and signal processing 8 (1989), S. 445-453 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract An optimization method is proposed for the design of high-order all-pass delay equalizers for a prescribed group-delay characteristic by using the cascade form realization of digital filters. Unlike other methods, in the proposed method stability is guaranteed by imposing certain mild constraints on the filter coefficients so that the unconstrained optimization technique of Fletcher and Powell is used. To reduce the function minimization time, design values of the parameters of the delay equalizers, obtained by Bernhardt's simplified method, are used as the initial vector in the optimization technique of the proposed method. It is shown that the proposed method for the design of optimal delay equalizers results in all classes of equalizers with real and complex poles and approximates the prescribed group delay more accurately.
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    Call for papers (1989)
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    Circuits, systems and signal processing 8 (1989), S. I 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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    Realizations of nonlinear systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 487-506 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Given the Volterra series representation of a single input, single output nonlinear system, we examine conditions on the Volterra kernels that determine if the system is in some sense equivalent to a linear system. The systems considered herein are known as “feedback linearizable” systems. Feedback linearizable systems are usually discussed in terms of their state-space representations. A key result relates the Volterra series description of a feedback linearizable system to its state-space description.
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    Therapeutic laser guidelines: On the effects of laser radiation on human skin-fibroblast metabolism in culture (1989)
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    Lasers in medical science 4 (1989), S. 31-40 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Summary A promising field of laser utilization is the modification of cell behaviour. Acting on cell biological functions it might be possible to use them to improve medical therapies. This possibility suggests investigation of dosimetry guidelines employing different wavelenghts, power and exposure durations for future potential use of lasers in medicine. In this line of investigation, structural organization and viability of fibroblast has been studied, thus observing that the cell number remains unaltered by low density laser irradiation. Nevertheless, results observed in metabolism variation suggest that, with appropiate irradiation-protocol an efficient modality for enhancement or modulation of cell activity can be found, and thereafter used for therapeutical pourposes.
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    Experimental effects of Argon and CO2 lasers on skin and vessels (1989)
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    Lasers in medical science 4 (1989), S. 95-103 
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    Topics: Medicine , Physics , Technology
    Notes: Summary Response of rabbit ear blood vessels and defects on the pig skin to Argon and CO2 lasers, (1 to 4 Watts and 0,1 to 0,2 sec pulses), were analysed. Examining lesion depth and its diameter, it was seen, using both lasers, that when power and time exposure increased, lesion depth increased as well, At the same time, when power was increased and the time of irradiation was constant, the diameter of the lesion remained approximately the same. Histologically, by using Argon laser at 1'5 W, there is no evidence of skin lesion but vessel coagulation occurs. On the other hand, more power (3 to 4 W) produces skin destruction. CO2 laser at 1'5 W causes skin destruction while 3 W penetrates deeper, cutting all tissues and producing vessel-wall fragmentation and haemorrhage. In contrast to CO2 laser, which definitly stops blood circulation by cutting the vessels, Argon laser entails many recurrences and vessels re-start circulation; a fact which is not desirable in cutaneous vascular disorders treatment.
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    The present state of safety laws and regulations in the FRG (1989)
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    Lasers in medical science 4 (1989), S. 213-213 
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    Topics: Medicine , Physics , Technology
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    Title: Development of national safety regulations for medical use of lasers in the Netherlands (1989)
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    Lasers in medical science 4 (1989), S. 235-238 
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    Topics: Medicine , Physics , Technology
    Notes: Abstract Until now there are no national safety regulations for the medical use of lasers in the Netherlands. However, a committee of experts from hospitals, Health Council of the Netherlands, TNO Medical Technology Unit and industry is preparing recommendations. Their work is based on MPE values and special measurements that are performed to assess divergence and intensity distribution of laser beams, as well as optical and thermal properties of materials that are used in the clinical setting. The final intention of the committee is to advise government and hospitals on technical, environmental and administrative measures for the safety of the various medical laser applications.
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    The accident prevention regulation “Laser Radiation” (VGB 93) — Special regulations for the safe use of laser products in the Federal Republic of Germany (1989)
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    Lasers in medical science 4 (1989), S. 243-249 
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    Notes: Abstract Accident prevention regulations, e.g. VBG 93 “Laser Radiation”, are a national particularity in the FRG. The regulations issued by the injuries insurance institutes are binding upon employers and employees. The apparatus and equipment safety law makes the VBG 93 obligatory also for manufacturers and importers. National and international standards are referred to in relevant context in the VBG 93. The VBG 93 is also used by the governmental authorities for the protection of labour. The medical apparatus decree has to be observed also for medical application. Some important aspects of the VBG 93 will be described in detail.
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    Proposal for dosimetry of non-ionizing radiation (1989)
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    Lasers in medical science 4 (1989), S. 329-340 
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    Notes: Abstract In general “Dose” by itself as an amount of energy is not a relevant parameter for the description of penetration by non-ionizing (laser) radiation. But dosimetry should not only include the measurements of relevant parameters and its relatioships to tissue effects but also include all possibilities of measurements and relationships which help to control the biological result on tissue by irraditation with non-ionizing laser radiation.
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    Laser therapeutic guidelines used in the Lisbon Institute of Ophthalmology (1989)
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    Lasers in medical science 4 (1989), S. 361-365 
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    Topics: Medicine , Physics , Technology
    Notes: Abstract In this paper the Author presents the guidelines of laser therapy in the Lisbon Institute of Ophthalmology, with spetial referance to the laser parameters, the ocular pathology imposing laser therapy and the necessary conditions for safety of the patient and of the doctor, operating with laser.
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    Study of laser-tissue interactions through Raman spectroscopy (1989)
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    Lasers in medical science 4 (1989), S. 41-61 
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    Notes: Abstract A review is presented of Raman spectroscopic applications in the study of laser-tissue interactions. The basic definitions of Raman spectroscopy are given with emphasis to those concepts and techniques which are relevant to biomedical material characterization. Representative problems from current literature will be discussed, like atherosclerosis of human vessels, eye lens aging, formation and diagnosis of cataracts.
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    Comparison of lasers for photodynamic therapy with a phthalocyanine photosensitizer (1989)
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    Lasers in medical science 4 (1989), S. 7-12 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Three different lasers were compared under the same conditions for their effectiveness at producing photodynamic damage to normal colon following sensitization with aluminium sulphonated phthalocyanine (AlSPc). One laser was an argon ion pumped continuous wave (CW) dye laser and the other two were pulsed at 10 kHz (copper vapour laser pumped dye laser, and 5 Hz (flashlamp pumped dye laser). The CW and 10 kHz laser were equally effective at producing damage. The 5 Hz laser failed to produce a photodynamic effect, although occasionally caused a photomechanical effect when the laser fibre was placed touching the colonic mucosa. Quantitative analysis suggests that the high energy pulses of the flashlamp pumped dye laser saturate AlSPc, so very little of the available energy can be used to produce a photodynamic effect, in contrast to the two other lasers which do not produce saturation conditions.
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    Effect of the non-contact mode of YAG laser on pulmonary tissues and its comparison with electrodiathermy: An anatomo-pathological study (1989)
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    Lasers in medical science 4 (1989), S. 17-23 
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    ISSN: 1435-604X
    Keywords: YAG Laser/Electrodiathermy ; Pulmonary tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract An anatomo-pathological study was undertaken to evaluate the early effects of high and low powered non-contact mode of YAG laser on pulmonary tissue and to compare these effects with those resulting from electro-diathermy. In 40 patients with bronchial carcinoma, thoracotomy was carried out using conventional surgical methods, the part of the lung destined to be excised was then exposed to: Non-contact YAG laser of high or low power (Group A, n=15); cutting/ or coagulation electro-diathermy (Group B,n=15); and mixed (blend) cutting and coagulation electro-diathermy (Group C,n=10). The results indicated that high power non-contact YAG laser is capable of incising the pulmonary parenchyma without bleeding or air leak, only the larger and sub-segmental vessels and bronchial branches needed suturing. This was not the case for electro-diathermy, either in its cutting or blend form. The low power laser was capable of sealing off the superficial bleeding vessels and contracting the alveolar sacs, thus preventing bleeding and air leak. Only the superficial bleeding could be stopped by coagulation diathermy which had no effect in preventing air leak from the parenchyma. Microscopically, apart from evaporation, laser produced charring and coagulative necrosis in the remaining exposed tissue. No evaporation of tissue occurred with electro-diathermy (either in its cutting, blend or coagulation mode). Only a very limited charring and coagulative necrosis was present in the remaining tissues exposed to coagulation electro-diathermy.
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    Open lung surgery with Nd-YAG Laser (1989)
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    Lasers in medical science 4 (1989), S. 13-16 
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    Keywords: Nd-YAG laser ; Open lung surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We report on nineteen patients who successfully underwent open lung performance with a Nd-YAG laser in the period December 1987 to August 1988. Reasons for laser operations were lung metastases (twelve cases), lung fibrosis (five patients), one lung cyst and one tuberculoma. We used the Nd-YAG laser in non-contact mode, with focus hand-piece spot size of 1.5 mm, a continual 1064 nm wavelength and a power output 90 W. In these nineteen cases we performed 35 laser photoablations of lung tissue. All patients healed without any serious complications. The major advantage of Nd-YAG laser beam in open lung surgery is in the rapid sealing effect of small airways and of blood vessels up to 3 mm. The Nd-YAG laser seems to be very suitable for operations in lung periphery.
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    Book reviews (1989)
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    Lasers in medical science 4 (1989), S. 65-65 
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 71-72 
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    Photodynamic treatment of cholesteatoma of the ear induced experimentally in rabbits: Preliminary report (1989)
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    Lasers in medical science 4 (1989), S. 111-113 
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    Keywords: Cholesteatoma ; Haematoporphyrin ; Photo-dynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In a previous project on haematoporphyrin (HP) uptake by experimentally induced cholesteatoma of the rabbit, it was shown that HP concentration was remarkably high in the cholesteatoma, with a peak at three hours after intravenous administration of the drug. On the basis of these results an attempt was made to destroy the matrix of cholesteatoma by means of photodynamic therapy. Cholesteatomas were induced bilaterally in the ears of eight rabbits which were divided into two groups, according to the interval between HP administration (5 mg/kg body weight) and irradiation. The irradiation was carried out with light at 600–680 nm, filtered from the emission a quartz halogen lamp (dose rate 300 mW cm−2; total dose 120 J cm−2). The first group was submitted to photodynamic therapy after three hours and the second after twelve hours. In both groups half the rabbits were sacrificed at 24 h and half at 48 h post-irradiation. Histological studies showed significant vascular lesions, necrosis of the wall of the cholesteatoma, interstitial extravasation of blood, and oedema in a high percentage of the animals. The lesions were much greater in animals sacrificed at 48 h after photodynamic therapy.
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 137-138 
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    Topics: Medicine , Physics , Technology
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    The role of the CO2 laser in out-patient oral surgery (1989)
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    Lasers in medical science 4 (1989), S. 151-154 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The treatments of 250 patients with the CO2 laser is described. The procedures were performed under local anaesthesia with minimal instrumentation apart from the laser. Operations were rapid and relatively bloodless, and excellent cosmetic and functional results were obtained. In the post-operative period there was minimal oedema and no significant bleeding. Post-operative pain was also minimal allowing patients to resume their normal diet on the first post-operative day and to return to work. The experience gained with this first group of patients suggests that ideal cases for treatment by this modality include leukoplakia, haemangiomas, epulis and prosthesis fibromas. The CO2 laser is now being used to a lesser extent on in-patients and on those with malignant lesions.
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    Laser-induced fluorescence used in localizing atherosclerotic lesions (1989)
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    Lasers in medical science 4 (1989), S. 171-181 
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    Keywords: Autofluorescence ; Laser-induced fluorescence ; Laser-induced breakdown spectroscopy ; Atherosclerosis ; Tissue diagnostics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We have investigated laser-induced fluorescence frompost mortem human arteries in order to find spectroscopic properties allowing discrimination between normal and atherosclerotic vessel wall. A pulsed nitrogen laser emitting light at a wavelength of 337.1 nm was used as an excitation source. The fluorescence spectrum from 370 to 700 nm was captured and analysed by an optical multichannel analyser. Dimensionless contrast functions were formed by using characteristic spectral features at 390, 415, 480, 580 and 600 nm. All samples were investigated in scans across a region where normal as well as diseased vessel wall appeared. The types of plaque were histopathologically divided into four groups, of which three could be singled out using one or more of our spectroscopic criteria. We also investigated the different layers of the normal and diseased vessel wall in order to determine the various contributions to the fluorescence signal. Furthermore, plasma emission spectra were recorded while ablating the normal as well as the diseased vessel wall with an excimer laser, emitting radiation at 308 nm, thus detecting the change in spectral characteristics during the ablation process down into deeper layers.
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 203-204 
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    Photodynamic therapy for the treatment of advanced gastrointestinal tumours (1989)
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    Lasers in medical science 4 (1989), S. 183-186 
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    Keywords: Photodynamic therapy ; Gastrointestinal tumour ; Advanced lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In the study, 120 patients with advanced gastrointestinal tumours were treated by PDT; 5 mg/kg of HpD was intravenously given 48–72 h prior to PDT. The light source was an argon dye laser with an output beam of 630 nm. The irradiation time varied from 15–25 min with a power of 100–350 mW cm−2. The entire tumour was irradiated with a light dose of 100–250 J cm−2. Of the 120 patients, 20 had cancer of esophagus, 72 had cancer of the gastric cardia, 18 had cancer of the stomach and 10 had cancer of the rectum. Eighty-eight patients (73.3%) had a response to PDT. Twelve patients with CR were followed up for one to five years, two patients died during the two years after PDT.
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    Identification of brain tumours in rats using laser-induced fluorescence and haematoporphyrin derivative (1989)
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    Lasers in medical science 4 (1989), S. 241-249 
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    Keywords: Brain tumour ; Rat ; Detection ; Fluorescence ; Laser ; Haematoporphyrin derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
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    New laser literature (1989)
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    Lasers in medical science 4 (1989), S. 285-287 
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    Topics: Medicine , Physics , Technology
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    A single transcutaneous light irradiation to injured peripheral nerve: Comparative study with five different wavelengths (1989)
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    Lasers in medical science 4 (1989), S. 259-263 
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    Keywords: Low-level laser irradiation ; Peripheral nerve injury ; Single effect of 632.8, 660, 830, 880 and 950 nm wavelengths
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Twenty rats underwent a crush injury to their sciatic nerve, followed immediately by a single low-power coherent or non-coherent irradiation administered transcutaneously on the projection of an injured peripheral nerve. Five wavelengths were tested: 632.8, 660, 830, 880 and 950 nm. The electrical activities of the crushed nerve, immediately after irradiation and on the following first, third and seventh day post-crush, were compared to the precrush activity. The results indicate that energy at the wavelength of 632.8 nm (CW He-Ne laser), delivered transcutaneously (10 J cm−2 at each point) along the projections of the nerve, prevents the drop in the functional nerve activity as measured by the combined action potential (AP) after crush injury. Other wavelengths were either less effective (660 nm) or totally ineffective under the same conditions. The beneficial effects were temporary and lasted only one day after injury and the single irradiation session.
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    New laser literature (1989)
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    Lasers in medical science 4 (1989), S. 199-202 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02032437
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    Report on the photodynamic therapy dosimetry meeting: April 1989 (1989)
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    Lasers in medical science 4 (1989), S. 211-220 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02032450
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    Argon laser therapy of port-wine stains—Prediction of the effect by transcutaneous microscopy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 237-240 
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    ISSN: 1435-604X
    Keywords: Argon laser ; Port-wine stains ; Transcutaneous microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Sixty-two consecutive patients presenting with facial port-wine stains were examined by transcutaneous microscopy prior to argon laser treatment. The capillary morphology was classified and the late outcome was independently examined and scored. It was found that capillary appearances do have some value in predicting a favourable response and in predicting scarring.
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    Argon laser treatment of solid Ehrlich carcinoma tumours sensitized with some porphyrin compounds (1989)
    Springer
    Lasers in medical science 4 (1989), S. 265-268 
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    ISSN: 1435-604X
    Keywords: Argon laser, Photodynamic therapy ; Cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The effect of continuous-wave argon laser radiation on the growth of solid Ehrlich carcinoma was studied in mice. To enhance the tumour sensitivity to laser radiation, compounds of a porphyrin series were given to animals prior to the laser treatment. Out of 14 substances tested, tetraphenylporphyn-sulphonate and its palladium complex had the most pronounced photosensitizing activity comparable with that of haematoporphyrin derivative (HPD). Metallic complexes of tetraphenylporphyn and protoporphyrin were less active. It is concluded that porphyrins are promising sensitizers for photodynamic therapy (PDT).
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 289-290 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02032462
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    Photodynamic therapy in the treatment of malignant tumours of the upper aerodigestive tract (1989)
    Springer
    Lasers in medical science 4 (1989), S. 279-284 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Haematoporphyrin ; Argon dye laser ; Early stage esophageal cancer ; Head and neck cancer ; Squamous cell carcinoma ; Adenocarcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This is the report of a pilot study in which the technique of photodynamic therapy (PDT)—in which malignant tissues are destroyed by light after being previously photosensitized by haematoporphyrin or its derivative—was performed using a high power argon-dye laser system which operated at 630±5 nm and optical fibres with either a microlens or a diffusing tip. A total of thirty-seven patients were utilized for this study, including twenty-five patients affected by esophageal carcinoma, five by recurrences of head and neck cancer, four by gastric cancer and three by lung cancer. Among the sixteen cases with superficial or localized cancer of the esophagus, complete and partial responses were observed in seven and six patients, respectively. In advanced and recurring cancers less satisfactory results were obtained. Thus, PDT seems to be useful in cases of small superficial cancers, either primary or recurrent after previous treatments.
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    Proton NMR study on the molecular motion and conformation of polyaniline doped with HCl (1989)
    Springer
    Polymer bulletin 21 (1989), S. 221-228 
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    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 Proton NMR spectra and spin-lattice relaxation time (T1) for polyaniline doped with HCl were measured at 90MHz over a temperature range of 110–430K. A narrow line with a width of about 1–2KHz superimposed on broad NMR peak was observed above 210K, and it was tentatively assigned to the protons in dopant and absorbed water. The analysis of linewidths and second moments for the broad lines reveal two distinct relaxation processes with activation energies of 1.9 and 7.8Kcal./mole,respectively. The former may be associated with the motion of the dopant and water absorbed and the latter with the rotation of benzoid ring about C-N bond axis. The second moment data suggest that the twist angle between the adjacent rings decreases with rising the doping ratio. Proton NMR relaxation rate was fitted with a theoretical equation containing the contributions from nuclear dipolar interaction and from electron-proton interaction, Rd and Rp, respectively.Rd is negligible below room temperature and Rp has little change above 100K. The total relaxation rate is dominated by Rp near room temperature.
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    Acrytonitrile block copolymers (1989)
    Springer
    Polymer bulletin 21 (1989), S. 259-263 
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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 Acrylonitrile was polymerized by an insertion process on being added to solutions containing the adduct of the reaction of tetrakis(dimethylamino) titanium (T4) and azobisisobutyronitrile (AIBN). The obtained azo-linked polyacrylonitrile has appropriate initiating functionality for a subsequent vinyl polymerization.
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    The stabilization effect of mixed-surfactants in the emulsion polymerization of styrene (1989)
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    Polymer bulletin 21 (1989), S. 301-308 
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    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 emulsion polymerization of styrene was performed at 50°C with a mixture of anionic and nonionic surfactants using different surfactant concentrations. In the single-surfactant systems, a proportional relationship was observed between the total particle surface area per cm3 of aqueous solution at 90% conversion (TS) and the amount of surfactant used for each polymerization. For mixed-surfactant systems an additivity was established between the TS value and surfactant composition. The study of the particle size data from low to high conversion showed that the particle number changed with conversion.
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    Reductive silylation of chloroprene (1989)
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    Polymer bulletin 21 (1989), S. 335-340 
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    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 Copolymers made up of 1,4-(2-trimethylsilyl-1,3-butadiene) (I) and 1,4-(2-chloro-1,3-butadiene) (II) units have been prepared by reaction of chloroprene with trimethylchlorosilane and sodium dispersion in THF. The ratio of I∶II units in the copolymers have been determined by IR,1H NMR and elemental analysis. The E∶Z ratio of these units has been determined by1H NMR.13C and29Si NMR of these copolymers is discussed.
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    Synthesis of an amphigel by the terpolymerization of 2-methyl-2-oxazoline, 2-alkyl-2-oxazoline, and bis-oxazoline (1989)
    Springer
    Polymer bulletin 21 (1989), S. 353-356 
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    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 terpolymerization of 2-methyl-2-oxazoline, 2-alkyl-2-oxazoline (alkyl = n-butyl, n-octyl, n-dodecyl), and 2,2′-tetramethylenebis(2-oxazoline) was carried out with methyl trifluoromethanesulfonate initiator. The obtained gel was isolated in a moderate yield after Soxhlet extraction. The resulting gel showed a characteristic property as an amphiphilic gel (amphigel), i.e., it was swollen both in water and in organic solvents such as N,N-dimethylformamide (DMF), n-propanol, 1,2-dichloroethane, diethyleneglycol dimethyl ether (diglyme) and toluene.
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    Thermodynamic properties of poly(ethyl methacrylate) in binary mixtures (1989)
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    Polymer bulletin 21 (1989), S. 89-96 
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    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 Behaviour of poly(ethyl methacrylate) (PEMA) in ethyl acetate/ethanol system has been studied. Preferential sorption of ethyl acetate in the composition range studied has been observed. This is justified for the self-association of alcohol and the formation of 1∶1 complex between this one and ethyl acetate.
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    An estimation of the chain branching effects in butene/ethylene copolymers from microhardness measurements (1989)
    Springer
    Polymer bulletin 21 (1989), S. 513-516 
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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 In this work a simple microhardness test to evaluate the degree of chain braching in butene-ethylene copolymers is proposed. The random introduction into the chain of co-units, reduces the level of crystallinity in the copolymer, a characteristic easily measurable through indentation experiments. A comparative study between density and microhardness values in samples with different concentration of chain braching is presented.
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    Meaning of molecular weight measurements of gum arabic (1989)
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    Polymer bulletin 21 (1989), S. 517-521 
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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 weight-average MW and number-average Mn molecular weights of gum arabic are identical after a proteolysis treatment with pronase. The value (1.8×105) is closed from Mn early reported in the literature whereas MW before treatment are dispersed for a large lot of samples up to more 106. This can be interpreted by the “wattle blossom” model for which some homogeneous chains of molecular weight c.a. 2.105 are still linked to a protein core, the crude gum being a mixture of this complex and free chains.
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    Rapid microanalytical chlorine determination in polymers by ion selective electrode (1989)
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    Polymer bulletin 21 (1989), S. 281-286 
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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: Abstract A rapid microanalytical method has been developed for the determination of very small amounts of chlorine in polymers. The gist of the method comprises quantitative dechlorination by sodium biphenyl or dehydrochlorination bytert-BuOK, aqueous extraction of the Cl⊖ formed, followed by [Cl⊖] quantitation by chloride ion selective electrode (CSE). The method has been tested and is now used routinely for chlorine end group quantitation of telechelic polyisobutylene (PIB), poly(2,4,6-trimethylstyrene) (PTMSt), and poly(p-chlorostyrene) (PpClSt).
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    Living carbocationic polymerization (1989)
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    Polymer bulletin 21 (1989), S. 273-280 
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    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 The living polymerization of isobutylene (IB) by thetrans-2,5-diacetoxy-2,5-dimethyl-3-hexene (DiOAcDMH 6 = )/BCl3 initiating system in 1,2-dichloroethane (DCE) in the −30 to +21°C range has been investigated. Well-definedtert-chlorine terminated polyisobutylenes ( $$^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{t} } Cl - PIB - Cl^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{t} } $$ ) have been obtained at suitably low IB and DiOAcDMH 6 = concentrations in the −30° to 0°C range. Theoretical $$Cl^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{t} } $$ end functionality ¯Fn ∼2.0 ±0.1 was demonstrated by dechlorination with sodium biphenyl coupled with titration using a chloride ion selective electrode, and by1H NMR spectroscopy. The $$^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{t} } Cl - PIB - Cl^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{t} } $$ was quantitatively dehydrochlorinated to ∼CH2C(CH3) =CH2 capped PIBs which in turn were quantitatively converted by hydroboration/peroxidation to ∼CH2CH(CH3)CH2OH ended PIBs. The internal ∼C(CH3)2CH=CHC(CH3)2∼ initiator fragment in the polymer remains unchanged during end group functionalizations due to steric protection by thegem-dimethyl groups and the polymer chain.
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    On the use of watersoluble carbodiimides for binding carboxylic compounds to aminated dextrans (1989)
    Springer
    Polymer bulletin 21 (1989), S. 309-313 
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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 To prepare dextran-linked benzene polycarboxylic acids which are stable in-vivo, the acids were allowed to react with aminated dextrans in water, in the presence of a water-soluble carbodiimide. Under these conditions, ester linkages are formed preferentially to amide ones, probably because of the formation of intramolecular cyclic anhydrides promoted by the carbodiimide. Thus, with benzoic acid, esterification also took place, but to a much lesser extent.
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    The influence of aging on the effectiveness of an organophosphite in suppressing transesterification in polymer blends (1989)
    Springer
    Polymer bulletin 21 (1989), S. 327-334 
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    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 Organophophites are being used with varying degree of effectiveness to suppress transesterification in polyester blends. Using solid state31p NMR it was discovered that for bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite a conversion of the phosphite group to a phosphonate moiety, probably via hydrolysis, is a prerequisite for an effective inhibition of transesterification. This conversion occurs readily during melt compounding if the polymers are not completely dry. However, if rigorous drying is employed and phosphite conversion does not occur, then transesterification is not arrested. It was also found that over a long period of time the conversion of the phosphite to a phosphonate takes place at room temperature as well. Thus, after aging for about a year, the originally ineffective compound, has become a very effective inhibitor of transesterification in blends containing polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarylate.
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    Osmotic pressure of catenanes in solution (1989)
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    Polymer bulletin 21 (1989), S. 655-657 
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    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 We propose a nonuniversal scaling for the osmotic pressure in the case of concatenating ring polymers. The size exponent depends on the molecular weight of the catenans. The effect is more significant the shorter and the stiffer the molecules are.
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    Plasma polymerization of fluorobenzenes/SO2 mixtures (1989)
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    Polymer bulletin 22 (1989), S. 15-20 
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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 Plasma polymerization of mixtures of fluorobenzenes (perfluorobenzene (PFB), pentafluorobenzene (PnFB), and tetrafluorobenzene (TFB)) and sulfur dioxide (SO2) is carried out for preparation of plasma polymers containing both fluorine and sulfur moieties. The chemical composition of the polymers is inspected by FT/IR and XPS, and the ion-exchange capacity and the electrical conductivity are measured. Plasma polymers prepared from these mixtures are fluro polymers with either of sulfonic acid or sulfinic acid groups. The ion-exchange capacity is 0.49 (for polymers from the PFB/SO2 mixture), 0.94 (for those from the PnFB/SO2 mixture), and 1.31 meq/g-polyer (for those from the TFB/SO2 mixture). The electrical conductivity at a relative humidity of 70 %RH is 8.3 × 10−9, 3.6 × 10−7, and 4.3 × 10−5 S/cm, respectively.
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    Synthesis of diacetylenic-butadiene-acrylic acid block copolymers (1989)
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    Polymer bulletin 22 (1989), S. 21-24 
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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: Synopsis This paper describes the synthesis and post-polymerization in solution of a copolymer 1,3-butadiene-acrylic acid modified with diacetylenic pendant groups. The products were characterized by UV, IR and NMR spectorscopy.
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    URL: http://dx.doi.org/10.1007/BF00283279
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    Synthesis of imide-aryl ether benzoxazole block copolymers (1989)
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    Polymer bulletin 22 (1989), S. 47-53 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Imide-aryl ether benzoxazole multiblock copolymers were investigated. A key feature of these copolymers was the preparation of bis(amino) terminated aryl ether benzoxazole oligomers (PBO) via a novel nucleophilic aromatic displacement polymerization. Oligomers with number average molecular weights of 10,500 and 26,000 g/mol were prepared, which displayed Tg's of 210 and 227°C, respectively. The oligomers were co-reacted with 4,4′-oxydianaline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in a NMP/ cyclohexanone solvent mixture in the presence of N-methylmorpholine. The resulting amic ester-aryl ether benzoxazole copolymers were isolated and washed to remove homopolymer contamination. Copolymer compositions were analyzed by 13C NMR. Solutions of the copolymers were cast and cured to effect the imidization, affording tough films with high elongations. Multiphase morphologies were obtained for both of the PBO block lengths used in the copolymerization.
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    Reductive transformations (1989)
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    Polymer bulletin 22 (1989), S. 137-141 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary 2,3-Diheptyl- and 2,3,6,7-tetraheptyl-9, 10-anthraquinone are reduced to the corresponding diols and subjected to esterification with the chlorides derived from mono- and di-acids. The resulting polyesters are nicely soluble in organic solvents and can be characterized by vapor pressure osmometry and NMR spectroscopy.
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    Characterization of the conformers in poly(3,3-diethyl oxetane) by vibrational spectroscopy (1989)
    Springer
    Polymer bulletin 21 (1989), S. 85-88 
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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 monoclinic and orthorhombic conformers of Poly(3,3-Diethyl oxetane) can be obtained depending on crystallization temperature. However, if the crystallization of a given modification is unaccomplished, the other modification can be crystallized from the amorphous phase. The molecular vibrations in the region 700–800 cm−1, which are associated with the “breathing” mode, are highly dependent on the conformation of the polymer chain. This band is used to study the influence of the temperatures and times of crystallization on the structural modifications of this polymer.
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    Polymerization of methylmetacrylate in the presence of quaternary ammonium salts (1989)
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    Polymer bulletin 21 (1989), S. 151-158 
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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 At 50°C, trioctyl methyl ammonium salts influence the rate of bulk polymerization of methylmetacrylate initiated by dibenzoyl peroxide. Acetate increases it, chloride, chlorate, and bromate increase it only on start, hydroxide, bromide, tetrachlorozincate, trifluoroacetate and trifluoromethanesulfonate decrease it, iodide and dichromate inhibit the polymerization, whereas fluoride, perchlorate, some (substituted) benzoates as well as sulfonates do not change the reaction rate. The influence on kinetic parameters of polymerization and the formation of intermediates and products suggest that the exchange of anions between the quaternary ammonium salt and dibenzoyl peroxide is the primary mechanism of action of these salts and other effects accompany it.
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    Synthesis and photodegradation of poly[2,5-bis(dimethylsilyl)thiophene] (1989)
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    Polymer bulletin 21 (1989), S. 133-140 
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    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 Poly[2,5-bis(dimethylsilyl)thiophene] (I), a copolymer with alternating thiophene and disilyl units, has been prepared by the Wurtz coupling of 2,5-bis(dimethylchlorosilyl)thiophene (IV) with sodium metal in toluene. I has been characterized by 1H, 13C, and 29Si NMR, IR, UV, GPC, TGA and elemental analysis. The photolysis of I in benzene/methanol solution results in degradation of the polymer. The structure of the photoproducts and possible mechanisms for their formation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266163
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    Birch reduction of the dichlorocarbene adduct of poly(1,1-dimethyl-1-sila-cis-pent-3-ene)(Cl2C-I): synthesis and characterization of poly(1,1-dimethyl-3,4-methylene-1-sila-cis-pent-3-ene) CH2-I) (1989)
    Springer
    Polymer bulletin 21 (1989), S. 173-177 
    Details
    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 Birch reduction of the dichlorocarbene adduct of poly(1,1-dimethyl-1-sila-cis-pent-3-ene) (Cl2C-I) yields poly(1,1-dimethyl-3,4-methylene-1-sila-cis-pent-3-ene) (CH2-I) which has been characterized by 1H, 13C and 29Si NMR spectroscopy as well as by elemental analysis. The molecular weight distribution of CH2-I has been determined by GPC and its thermal stability by TGA. Its glass transition temperature was obtained by DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266169
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  • 86
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    Miscibility of poly(methyl methacrylate-co-vinyl pyridine) and poly(butyl acrylate-co-acrylic acid) blends (1989)
    Springer
    Polymer bulletin 21 (1989), S. 183-188 
    Details
    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 In order to enhance the miscibility of poly(methyl methacrylate) and poly(butyl acrylate), pyridyl and carboxylic acid groups were introduced on the comonent polymer chains by free radical copolymerization. Differential scanning calorimetry shows that the blend of component polymers containing less than 10 mole% of carboxylic acid and pyridyl groups is immiscible, but the blend of more than 10 mole% become partially to completely miscible as the functionality increases. The chemical interaction between carboxylic acid and pyridyl group in the blend was manifested by a blue shift of 9 cm−1in the infrared stretching frequency of pyridyl group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266171
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  • 87
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    Properties of urethane elastomers (1989)
    Springer
    Polymer bulletin 21 (1989), S. 203-207 
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    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 dielectric relaxation processes in polyurethanes based on 4,4′-dibenzyle diisocyanate and saturated polyester in the temperature range of 250–400°K using thermally stimulated depolarization currents method have been investigated. The structure of the relaxation thermograms, location and intensity of the constituent peaks depend both on the precipitation temperature and thermal history of the polymer. The relaxation processes have been associated with the molecular motions within domains with distinct morphological structures. The morphological structure of the samples was evidenced using electron microscopy method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266174
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  • 88
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    Carbon-13 NMR assignments for 2,4,7-trinitro-9-fluorenone and 2,4,5,7-tetranitro-9-fluorenone (1989)
    Springer
    Polymer bulletin 21 (1989), S. 217-220 
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    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-dimensional pulse sequences (COSY, HETCOR) are used to assign the carbon-13 spectra of 2,4,7-trinitro-9-fluorenone and of 2,4,5,7-tetranitro-9-fluorenone.
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    URL: http://dx.doi.org/10.1007/BF00266176
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  • 89
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    Polymerization of 2-phenyl-aziridine (1989)
    Springer
    Polymer bulletin 21 (1989), S. 243-250 
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    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 ring-opening polymerization of 2-phenyl aziridine was studied with several catalyst systems: boron trifluoride etherate, chlorhydric acid, perchloric acid, dimethyl sulfate and methyl triflate. The corresponding polyamine was obtained as a pale yellow solid with a number average molecular weight around 2,000–3,000. A kinetic study is discussed in the case of perchloric acid and methyl triflate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00955914
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  • 90
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    DSC and TMS study of polystyrene/(poly(α-methylstyrene) blends (1989)
    Springer
    Polymer bulletin 21 (1989), S. 265-272 
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    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 It is shown that Tg data of PS/PaMS blends are influenced by the pressure applied during the preparation of compression-moulded samples. It is supposed the pressure favours the chain alignment of stiffer polymers in the neighborhood of binary contacts, contributing thus to the reduction of the freee volume. As a consequence compression-moulded samples will show increased Tg temperatures compared with those of the solution blended samples.
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    URL: http://dx.doi.org/10.1007/BF00955917
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  • 91
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    The role of complexation in living cationic polymerization with Lewis acid/ester systems (1989)
    Springer
    Polymer bulletin 22 (1989), S. 341-347 
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    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 Higashimura reported living cationic polymerization by the CH3OOOEt/AlEtCl2/C6H5CH3 /IBVE system, however, the mechanism was obscure and the high mole ratio of CH3OOOEt/ AlEtCl2 (50/1) was unusual. To elucidate these facts the AAlEtCl2·CH3OOOEt complex was investigated in detail by 1H-NMR, IR and UV spectroscopies. It was found that CH3OOOEt was the true initiator, AlEtCl2 the coinitiator, and the ester bond the active bond. UV spectra show complexation competitions of AlEtCl2 with C6H5CH3, CH3OOOEt and H2O. Living polymerizations occur only when the CH3OOOEt/AlEtCl2 ratio is sufficiently high. The growing bands from 324 to 327nm correspond to living complexes and indicate constant monomer insertion and complex formation during propagation.
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    URL: http://dx.doi.org/10.1007/BF00263071
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  • 92
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    Synthesis and characterization of new polyimides and polyamide-imides containing azomethine group in the polymer backbone (1989)
    Springer
    Polymer bulletin 22 (1989), S. 371-378 
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    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 New aromatic polyimides and polyamide-imides containing azomethine linkages in the polymer backbone have been synthesized by reacting 4,4′-bis(isocyanato) benzylidene aniline (AZMI) with pyromellitic dianhydride (PMDA), 3,3′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and trimellitic anhydride (TMA) by one-step method. The AZMI was synthesized from 4,4′-bis(carboxy) benzylidene aniline (AZMA) by a Weinstock modified curtius rearrangement. All the polycondensation reactions were carried out in N-methyl-2-pyrrolidone (NMP) and the polymers obtained were characterized by infrared spectroscopy, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction.
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    URL: http://dx.doi.org/10.1007/BF00263075
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  • 93
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    Poly(methyl methacrylate-g-propylene oxide) (1989)
    Springer
    Polymer bulletin 22 (1989), S. 401-406 
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    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 Graft copolymers with uniform poly(propylene oxide) grafts were synthesized by the radical copolymerization of poly(propylene oxide) methacrylate macromonomers and methyl methacrylate. The macromonomers were prepared by reaction of bifunctional poly(propylene oxide) and methacryloyl chloride. The graft copolymers were readily soluble in chloroform, tetrahydrofuran and toluene at room temperature. Copolymers with 23% of poly(propylene oxide) grafts were soluble in hot methanol and above this composition were soluble in methanol at room temperature. The graft copolymers were characterized by GPC, viscometry, IR and 1H NMR spectra.
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    URL: http://dx.doi.org/10.1007/BF00263079
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  • 94
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    Molecular weight dependence of excimer formation of poly(α-methylstyrene) (1989)
    Springer
    Polymer bulletin 22 (1989), S. 429-433 
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    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 molecular weight dependence of the fluorescence properties of poly (α-methylstyrene) (PMS) was investigated in cyclohexane solution. The ratio of excimer to monomer fluorescence intensity increases with increasing degree of polymerization up to ∼ 50 after which the plateau value does not change. This molecular weight dependence of the excimer formation appears to be related to that of the local motion of PMS in fluid solution.
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    URL: http://dx.doi.org/10.1007/BF00263083
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  • 95
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    Behavior of deoxophostones family as nucleophilic monomers in no-catalyst copolymerization (1989)
    Springer
    Polymer bulletin 22 (1989), S. 435-440 
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    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 Deoxophostone family(2-phenyl-1,2-oxaphospholane1a, 2-phenyl-1,2-oxaphosphorlane1b, and 2-phenyl-1,2-thiaphospholane1c) copolymerized with acrylic acid without catalyst to produce the corresponding copolymers. The polymerization proceeded via a cyclic acyloxyphosphorane to produce poly-(phosphine oxide — ester)3a(or3b) from1a(or1b) and poly(phosphine oxide — thiolester)3c from1c, respectively, with acrylic acid. It is of interest that the copolymer from1c with acrylic acid was not poly(phosphine sulfide — ester)4 but3c. The reactions of1a or1b with pyruvic acid or 1,3-propane sultone were also investigated.
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    URL: http://dx.doi.org/10.1007/BF00718916
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  • 96
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    Macromolecular engineering of polylactones and polylactides (1989)
    Springer
    Polymer bulletin 22 (1989), S. 475-482 
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    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 Aluminum alkoxides carrying functional alkoxy groups are effective initiators for theɛ-caprolactone polymerization in toluene and tetrahydrofuran. The coordination-insertion type of polymerization is living and yields exclusively linear polyesters of a predictable molecular weight with a narrow molecular weight distribution within the period of time required for the total monomer conversion. The functional group associated to the active alkoxy group of the initiator is selectively attached to one chain-end, and the second end-group is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. Asymmetric telechelic polyesters are thus obtained in a perfectly controlled way, including macromonomers. Beside (meth)acrylic double bond, the functional end-group derived from the initiator can be, for instance, an unsaturation, a halogen and a tert-amine. Coupling the asymmetric telechelic polymer via the OH end-group (or the precursor Al alkoxide end-group) is a direct way to the related symmetric telechelic of a twofold increased molecular weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718922
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  • 97
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    Polymerization of 4-vinyl biphenyl at advanced degrees of conversion (1989)
    Springer
    Polymer bulletin 22 (1989), S. 505-511 
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    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 The bulk self-initiated polymerization kinetics, assuming total conversion, of the 4-vinyl biphenyl was determined by differential thermal analysis (DTA) in the temperature range 463–533 K. Likewise, the overall activation energy, Ea, and the polymerization enthalpies involved in the process have been calculated, as well as the overall rate constants and the reaction order with respect to the monomer concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718926
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    Studies on diacetylenic vinyl compounds (1989)
    Springer
    Polymer bulletin 22 (1989), S. 533-538 
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    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 The copolymerization of maleic anhydride (MAn) with phenyl-4′-vinylphenylbutadiyne(PVPB) was carried out using 2, 2′-azobisisobutyronitrile as an initiator. Although PVPB does not homopolymerize by free radicals in solution, it copolymerized giving copolymers having average molecular weights up to 12,000, and consisting of slightly more PVPB units. The monomer reactivity ratios were estimated to be r (MAn)=0 and r (PVPB) =0.1–0.2. It was concluded that the copolymerization likely proceeds via a free monomer propagation mechanism rather than through a donor-acceptor complex mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718930
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  • 99
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    Suppression of the influence of stray light on quantitative measurement of iD/iM for weakly emitting dilute solutions of polymers (1989)
    Springer
    Polymer bulletin 22 (1989), S. 557-563 
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    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 simple method is described for suppression of the influence of stray light on the quantitative measurement of the intensity of the fluorescence from dilute solutions of weak emitters. The method improves the reliability of the measurements of the fluorescence quantum yield under these conditions. It is also useful in the evaluation of the ratio of the intensities of excimer and monomer emission in systems that form intramolecular excimers with a small overlap of the monomer and excimer bands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718934
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  • 100
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    Photovoltaic properties and stability of I2-doped polyacetylene (1989)
    Springer
    Polymer bulletin 21 (1989), S. 523-529 
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    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 Polyacetylene was doped with evaporated iodine (I2). The characteristics of A1/cis-[CHIy]x/Au Schottky barrier solar cell was investigated. It is found that the maximum conversion efficiency is 2.67%. The solar cell parameters, such as open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (F.F.), and energy conversion efficiency (η), were measured under the various incident light intensity. The stability of the cell was also estimated by the variation of J-V curves in argon environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271977
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