Relationship of cytotoxic groups in organotin molecules and the effectiveness of the compounds against leukemia

Cytotoxicity of organotin compounds is assessed and their effectiveness against leukemia is discussed. The functional groups attached to the tin atom in organotin compounds control the cytotoxicity of the compound towards the thymus gland. The four organotin moieties which have the greatest toxic effect upon the thymus gland are the tri-n-butyltin, di-n-butyltin, tri-n-propyltin and di-n-octyltin groups. Compounds containing these groups also exhibit the poorest test-control ratio (T/C) values when tested as anti-cancer agents against leukemic mice using NCI protocol.     

Ultrasonic stress wave interaction with domain walls in KD2PO4

The experimental results on ultrasonic stress wave interaction with domain walls in KD₂PO₄ crystals are presented. It is shown that the interaction takes place only if stress waves are piezoelectrically coupled to ferroelectric polarization. The temperature dependence of domain wall mobility is found.     

Stable potentials,II

A family of stable one-dimensional potentials is shown not to be decomposable into the sum of a non-negative function and a function of non-negative type. This settles in the negative a question raised by Ruelle.Supported by National Science Foundation Grant GP 13627.Supported by National Science Foundation Grant GP 7469.     

Microdetermination of the degree of hydration of polysaccharides and glycoproteins

In the hydration of polysaccharides and glycoproteins a "glass transition effect" has been discovered, i.e., a phase transition, at certain critical values of the relative water-vapour pressure (P/P(s))(gt), of lyophilized preparations to a new state which is accompanied by a "glass transition" of the samples. The dependence of (P/P(s))(gt) the content of polysaccharide and glycoprotein has been shown. Conditions have been found which make it possible to measure the absolute value of the degree of hydration of such biopolymers at any values of p/p(s), by means of Karl Fischer titration.     

Polarization of 22 MeV neutrons elastically scattered from liquid tritium

The asymmetries from elastic scattering of 22.1 MeV incident neutrons was measured for 11 laboratory angles between 40° and 118.5°. The extrema are −60% at 85° (lab) and +98% at 110° (lab).     

Effects of Heterogeneous Fracture Aperture on Multiphase Production from Shale Reservoirs

Production simulation from fractured shale reservoirs is often performed by simplifying the hydraulic fractures as rectangular planes with homogeneous aperture. This study investigates the effects of heterogeneous fracture aperture and proppant distribution in realistic, non-rectangular fractures on the multi-phase production from shales. The heterogeneous hydraulic fractures are generated with the GEOS multiphysics simulator under realistic 3D stress field. These fractures are embedded into the TOUGH+ multi-phase flow simulator for production simulation. The results emphasize the importance of flow barriers within the hydraulic fractures, due both to low-aperture regions caused by the stress-shadow effect and the settling of proppant. The production rate is particularly sensitive to aperture heterogeneity if the flow barriers are close to the wellbore such that a great portion of fracture volume is isolated from the well. A stage-to-stage comparison reveals that production from different stages could vary significantly because the local stress field leads to different fracture area and aperture. The use of proppant prevents fracture closure, but if the propped regions are far from the well, they do not enhance production because flow barriers between these regions and the well act as bottlenecks. The present study highlights the importance of incorporating aperture heterogeneity into production simulation, provides insights on the relationship between flow barriers, proppant concentration, and well production, and proposes a practical method to mitigate numerical difficulties when modeling heterogeneous fractures.