Review Of Fundamental Studies Research Articles

THE HISTORY OF THE DEVELOPMENT OF IDEAS ABOUT PARTS OF SPEECH IN THE RUSSIAN LINGUISTIC SCIENCE

The article features the phases of the development of ideas about parts of speech in the Russian linguistics. The aim of this research is to analyze and compare approaches to parts of speech made by various Russian linguists. In spite of the fact that the classification of words into parts of speech has a very long history, going back to ancient grammars, the interest in the matter has never expired, in the Russian language at various phases of its development as well. An analytical review of fundamental studies devoted to this aspect has demonstrated that the theory of parts of speech in the linguistic science has got a distinct dialectical character. In this connection the investigation of the origin and development of Russian parts of speech is especially relevant not only for Russian linguistics, but also for the theory of language in general. As this research reveals, both the number and the status of parts of speech has changed in the process of their segmentation in the Russian language. The overview of their evolution in grammatical conceptions of Russian scientists is important as it helps to define the place of this category in the morphological system of the grammar. The theoretical significance of the article is in the revelation of study methods applied to parts of speech and their interpretation. The results of the research conducted can be used in the preparation of lectures and seminars in general linguistics, history of linguistics, history of language and theoretical grammar.

On Zhukovsky's Vortical Theory for Describing Flow Past a Propeller

The blade-based theory of a propeller is developed by providing exact solutions which do not require numerical integration of velocities from semi-infinite spiral vortices. The induced speed on a lifting line is shown to be describable in terms of coefficients of speed harmonics being multiples of the total number of blades. Speed harmonics of a k-blade propeller are shown to be equivalent to the respective harmonics of a single-blade propeller which are multiplied by the number of blades; this simplifies computation drastically. The first term in the series is the zero-order harmonic of an instantaneous speed; it is the Zhukovsky solution for the induced speed of a propeller with infinitely numerous blades. The second term in the series is the coefficient for the k-th speed harmonic, the third one for the 2k-th one, etc. This growth of the order of harmonics is revealed to drastically reduce amplitudes of the harmonics and accelerate convergence, especially for propellers with large numbers of blades. It is shown that kernels of these coefficients may be integrated analytically over the interval {0,∞} and transformed into a modified first-order Bessel function whose argument is a multiple of the harmonic order. The solutions are implemented in a “rapid” program for aerodynamic calculation of a propeller. An example analysis of circulation, instantaneous speeds, and total propeller characteristics is provided. Also, the article includes a brief review of fundamental studies by Professor Zhukovsky which have been the basis for the development of propeller aerodynamics research and helicopter technologies.

The dentin substrate: structure and properties related to bonding

Objectives: Dentin is a vital, hydrated composite material with structural components and properties that vary with location. These variations are reviewed along with alterations by physiological and pathological changes that allow classification into various forms of dentin. Structural characteristics and mechanical properties are reviewed and the limitations of our understanding of structure-property relationships for normal and modified forms of dentin are discussed with respect to their impact on dentin bonding. Recent progress in methods available to study dentin and its demineralization are emphasized with their promise to increase our understanding of dentin properties and structure. Data sources: Recent microstructural studies, focusing on scanning electron microscopy, atomic force microscopy and X-ray tomographic microscopy are included. A review of fundamental studies with emphasis on microstructurally sensitive methods, and prior reviews of basic mechanical properties are included with discussion of their correlation to composition and structure. Study selection and conclusions: Emphasis in this work was placed on the major structural components of the tissue, including the collagen based organic matrix and its mineral reinforcement, the distribution of these components and their microstructural organization as related to mechanical properties and response to demineralization. Little information is included on biochemical and developmental studies or on non-collagenous proteins and other organic components for which limited understanding is available with respect to their role in structure-property relations and influence on bonding. In spite of the fact that the complexity of dentin precluded a comprehensive review, it is clear that local structural variations influence properties and impact nearly all preventive and restorative dental treatments. Much more work is needed in order to understand differences between vital and non-vital dentin, and dentin from extracted teeth. Although our knowledge is rudimentary in certain areas, increasingly sophisticated methods of studying dentin should provide the necessary information to model structure-property relations, optimize dentin bonding, and improve many aspects of preventive and restorative dentistry.