Role of vacancies of a strongly strained crystal in the melting process

It has been shown that, apart from classical vacancies formed as a result of the thermal fluctuations, a crystal can contain so-called nonclassical vacancies of nonfluctuation nature. The latter vacancies appear when the temperature exceeds a critical value T _C . The factor responsible for their formation is a mechanical instability of an ideal crystal. The temperature T _C is a second-order phase transition point. The vacancies formed as a result of this phase transition are joined together into small clusters with sizes of the order of several atoms. The above transition makes a substantial contribution to the premelting process observed experimentally.     

Anisotropic and isotropic phases of polymer melts

The melting mechanism of polymer crystals is proposed. It is assumed that the melting happens due to forming supervacancies. This mechanism leads the appearance of anisotropic phase of a melt. It is shown that two phases—anisotropic and isotropic—can exist in polymer melts.     

Vacancies in a strongly strained crystal at low temperatures

It is shown that an equilibrium vacancy concentration can be noticeable even at a temperature close to absolute zero. This will be the case if the volume deformation of a crystal is higher than a critical value, which is a second-order phase transition point.     

Measuring internal forces of redundant structures

Certain guidelines were formulated for conducting mechanical and electronic design, calibration and installation of steel or aluminum transducers, which may be utilized to monitor internal forces in selected elements of a redundant structure, directly and independently, without a need for analysis. Two different transducers are discussed as examples. These were implemented in reinforced-concrete test structures at U.C. Berkeley, and revealed significant information regarding actual force responses. It is assessed that this information could not have been analytically predicted or experimentally measured in any other manner. Possible practical applications of such force transducers, in addition to their potential in experimental research, are suggested.     

Bridge-condition assessment by modal flexibility

A bridge-condition assessment method for evaluating the global state of health is formulated based on modal flexibility directly obtained by processing modal test data, complemented by structural identification. The method is proven and the experimental and analytical tools that have been developed for implementation are demonstrated on a three-span reinforced-concrete high-way bridge. Paper was presented at the 1993 SEM Spring Conference on Experimental Mechanics held in Dearborn, MI on June 7–9.     

Almost f-Cosymplectic Manifolds

The purpose of this paper is to study a new class of contact manifolds. Such manifolds are called almost f-cosymplectic manifolds. Several tensor conditions are studied for such type of manifolds. We conclude our results with two examples of almost f-cosymplectic manifolds.     

Vacancies in oligomer crystals

The conditions for the existence of supervacancies in oligomer crystals—defects typical of chain systems-are studied. These vacancies are shown to be nucleated when the temperature exceeds a certain critical threshold T _cr. The equilibrium concentration of supervacancies is calculated. Temperature T _cr is found to be the point of the second-order phase transition. The equation relating transition temperature T _cr and chain length is derived.     

Real-Time PCR analysis of af4 and dek genes expression in acute promyelocytic leukemia t (15;17) patients

Among several newly identified oncogenes, dek and af4 are attractive targets for researchers interested with leukemia. In this study quantitative Real-Time RT-PCR technique was used to define alterations in expression of dek and af4 genes associated with acute promyelocytic leukaemia (APL) t (15; 17). RNA samples obtained from bone marrow aspirates of fourteen APL patients, cDNA portions were labelled with Syber Green 1 dye and LightCycler analysis have been performed. Expression changes in patients were found not significant in comparison to healthy donors for af4 (P = 0.192) and dek (P = 0.0895). We suggest that af4 gene may have a role in leukomogenesis restricted to lymphoblastic lineage; also further studies must carry on with a larger series of patients in order to understand the relationship between the dek gene and APL. Our study was the first attempt for analysing dek and af4 genes in APL t (15; 17) patients by quantitative Real-Time RT-PCR. This rapid and sensitive method could be used to screen these genes in different types of leukaemia.