Murine thymic lymphoma is associated with a species-specific hematopoietic progenitor cell subpopulation

Many strains of laboratory mouse are uniquely susceptible to the development of T cell lymphoma/leukemia, either spontaneously or as a result of chemical or radiation exposure. In contrast, T cell leukemias or lymphomas which are relatively uncommon in human populations, are not easily induced by radiation, and are not generally associated with chemotherapy or chemical exposure. Evidence is presented to suggest that differences in the susceptibility to the development of these malignancies is related to subtle but important variations in the regulation of hematopoietic stem cell differentiation between these two species.     

Modeling of slag eye formation over a metal bath due to gas bubbling

When gas is bubbled through a molten metal, overlying slag is pushed to the side forming an open “eye” of exposed metal. Eye sizes were measured in room-temperature modeling over a wide range of conditions including the fluids to simulate slag and metal, gas flow rates, and depths of both fluids. A mechanistic model for eye size was developed from fundamental fluid flow considerations. The model expresses a dimensionless eye area in terms of a density ratio of the fluids and a Froude number. The model is consistent with the present experimental results and those of others in different liquid systems. Finally, previously published correlations for eye size have been critically evaluated.     

Transport phenomena in electric smelting of nickel matte: Part I. Electric potential distribution

An electric potential probe was constructed so that simultaneous, multiple measurements of electric potential could be made in a six-in-line electric furnace for smelting nickel calcine having a maximum transformer capacity of 36 MVA. When the electric potential distributions were compared with those calculated from the solution of the Laplace equation, it was evident that there was significant electric potential drop at the electrode surface, 100 to 120 V for an applied potential of 180 to 230 V and currents of 20 to 30 kA. The Soderberg electrodes were continuously oxidized in the slag, likely creating carbon monoxide. The electric potential drop at the surface was attributed to arcing through the carbon monoxide. Thus, heat was released in the immediate vicinity of the electrode due to arcing, as well as in the bulk of the slag by Joule heating. The proper distribution of heat dissipation is required for the transport model, developed in Part II of this series.     

Modeling of gas-liquid reactions in ladle metallurgy: Part II. Numerical simulation

A combined three-dimensional, Lagrangian-Eulerian model for gas-liquid flow in a ladle was developed. The model compared very well with available experimental results in Wood’s metal in terms of void fraction, liquid velocity, and plume bending. From the model, it was clear that the lateral lift force is responsible for plume spreading, whereas lateral drag forces bend the plume. The model was extended to include mass transfer to rising bubbles and at the free surface. The rate of reaction compared very well with the results of part I on the desorption of carbon dioxide from sodium hydroxide solutions.     

A brief abstinence test for college student smokers: A feasibility study.

Cigarette smoking among college students is prevalent and correlated with other unhealthy behaviors. Reinforced abstinence (e.g., contingency management) has been demonstrated to be an effective method for reducing substance use in a variety of populations and across a variety of drugs, including cigarettes. Reinforced abstinence has seldom been used specifically targeting a college student population. A Brief Abstinence Test (BAT) has been used to effectively reduce cocaine use among methadone maintenance patients (Robles, Silverman, Preston, Cone, Katz, Bigelow, & Stitzer, 2000). However, no published studies have investigated the use of a BAT to reduce the use of cigarettes. The current study implemented a 3-week intervention (Baseline 1, BAT, and Baseline 2 weeks) for smoking abstinence among college students. Forty-two percent of the sample met abstention criteria during the BAT. Carbon monoxide and urinalysis scores decreased significantly from Baseline 1 to the BAT phase but did not differ significantly from BAT to Baseline 2. These results suggest that the BAT may have utility initiating abstinence in both clinical and research contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction and measurement of soil bidirectional reflectance

A model for soil bidirectional reflectance distribution functions in visible and reflective infrared wavelengths is introduced and compared to data acquired in the field. The model is based on the representation of soil surfaces by a collection of opaque spheres sitting on a Lambertian horizontal surface. The model is not sensitive to increases in the sphere area index beyond a value of 0.4. For comparison, soil reflectance factor data were acquired on a tilled field from many view directions and for a range of solar directions. The observed reflectance factor distributions were consistent with those predicted by the function; maximum reflectance occurred in the antisolar direction and reflectance decreased with increasing phase angle. Increasing the surface roughness by different tillage methods did not substantially alter the directional anisotropy of the soil reflectance factors. The model was fit to the data by a nonlinear least-squares procedure     

Settling and clustering of silicon carbide particles in aluminum metal matrix composites

The settling of 14-μm silicon carbide particles in an aluminum-silicon alloy was monitored with an electrical resistance probe to measure thein situ particle voluem fraction. The rate of settling was much greater than expected from hindered settling of single 14-μm particles. From the observed settling rate, an equivalent hydrodynamic diameter and density of clusters of particles were deduced, 38 μm and 2740 kg/m³, respectively. Other work was analyzed with the same procedure; it was concluded that if the stirring prior to settling were intense, then the clusters would be smaller than with weaker stirring. The implications for foundry practice and mechanical properties are discussed.     

Monte carlo simulation of clustering of alumina particles in turbulent liquid aluminum

A Monte Carlo method was developed to simulate the formation of clusters of alumina particles suspended in a turbulent pure liquid aluminum melt. With this approach, the chaotic movements of small alumina particles suspended within eddies smaller than the Kolmogoroff microscale were treated in a similar way to Brownian motion, and clusters were assumed to form once these particles collided with each other. The results obtained from the simulation indicate that clusters form very quickly during vigorous stirring and that the formation kinetics at the very beginning of mixing follow a second-order behavior. Clustering has been observed previously in the SiC-Al system and was also observed in the Al₂O₃-Al system in the present work.