Refinement of the crystal structure of (RS)-carnitine hydrochloride

A single crystal of (RS)-carnitine hydrochloride has been obtained, and its crystal structure has been refined by an x-ray structural experiment.Tashkent Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 842–844, November–December, 1991.     

Nonaxisymmetric bulging of cylindrical shells made from polymeric material on prolonged loading

Forms of bulging of cylindrical shells prepared from polymeric materials caused by the action of a constant compressing load in the direction of the generatrix are discussed. The functions of the initial irregularities and the additional radial deflection and stresses are characterized by the Fourier series in a complex representation. When the problem in a geometrically and physically nonlinear formulation was solved, it was found that the form of the deformed surface is transformed, and the bulging of the shell at the critical instant takes place asymmetrically. This agrees with the experimental results.     

A new method for the evaluation of the reversible and irreversible fouling propensity of MBR mixed liquor

In this paper, a new fouling measurement method is presented as a pragmatic approach to determine a mixed liquor's fouling propensity. The MBR-VFM (VITO Fouling Measurement) uses a specific measurement protocol consisting of alternating filtration and physical cleaning steps, which enables the calculation of both the reversible and the irreversible fouling resistances. The MBR-VFM principle, set-up and measurement protocol are described as well as the evaluation of the fouling measurement method. Finally, the MBR-VFM was validated by comparing the fouling propensity measured on-line by the MBR-VFM in a lab-scale MBR with the fouling of the MBR membranes themselves. Our experiments indicated that the MBR-VFM can accurately measure fouling and that it can even be detected earlier than can be seen from the on-line filtration data of the lab-scale system itself. Furthermore, the differences measured in reversible and irreversible fouling seemed to be related to the observed impact of physical and chemical cleaning respectively. Therefore, the application of the MBR-VFM as an on-line sensor in an advanced control system, enabling the deployment of the measured fouling data for the control of membrane cleaning, seems feasible and will be tested in the near future.     

Neue Vorschl?ge zur Bestimmung des specifischen Gewichtes

Ohne Zusammenfassung     

Hygrothermomechanical behavior of composites under nonsymmetric environmental effects

The paper discusses analytical methods for the stimation of mechanical properties and the behavior of composite materials under unilateral environmental exposure. An advanced graphite/epoxy composite plate and a densified wooden strand board of different configurations were examined. It was found that midplane strains, curvatures, and warping at nonsymmetric moisture (or temperature) distribution depended on the moisture content profile, composite type, and configuration as well as stacking sequence of layers. The optimum configuration for hygrothermal response may not coincide with that of mechanical properties.Institute of Structural Engineering and Reconstruction, Riga Technical University, Riga, Latvia, LV-1048. Published in Mekhanika Kompozitnykh Materialov, Vol. 34, No. 4, pp. 507–518, July–August, 1997.     

Approximation of strength surfaces in plane stress

Approximation of strength surfaces in plane stress is considered with the use of the method of expansion of the function on a sphere by means of tensors. Examples of the approximation are given for certain composite materials.     

Strength of a viscoelastic liquid in quasistatic three-dimensional tension

Conclusions 1. An apparatus has been built with which experiments could be performed yielding, with a minimal spread of values, the quasistatic bulk strength of a liquid specimen.2. It has been established that the concentration of a polymer liquid does not significantly affect the experimental values of the liquid resistance to rupture. The strength of a viscous polymer liquid specimen is much lower than that of its low-viscosity solute.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 525–530, May–June, 1978.