Description of the thermodynamic properties and fluid-phase behavior of aqueous solutions of linear,branched, and cyclic amines

The SAFT-γ Mie group-contribution equation of state is used to represent the fluid-phase behavior of aqueous solutions of a variety of linear, branched, and cyclic amines. New group interactions are developed in order to model the mixtures of interest, including the like and unlike interactions between alkyl primary, secondary, and tertiary amine groups (NH₂, NH, N), cyclic secondary and tertiary amine groups (cNH, cN), and cyclic methine-amine groups (cCHNH, cCHN) with water (H₂O). The group-interaction parameters are estimated from appropriate experimental thermodynamic data for pure amines and selected mixtures. By taking advantage of the group-contribution nature of the method, one can describe the fluid-phase behavior of mixtures of molecules comprising those groups over broad ranges of temperature, pressure, and composition. A number of aqueous solutions of amines are studied including linear, branched aliphatic, and cyclic amines. Liquid–liquid equilibria (LLE) bounded by lower critical solution temperatures (LCSTs) have been reported experimentally and are reproduced here with the SAFT-γ Mie approach. The main feature of the approach is the ability not only to represent accurately the experimental data employed in the parameter estimation, but also to predict the vapor–liquid, liquid–liquid, and vapor–liquid–liquid equilibria, and LCSTs with the same set of parameters. Pure compound and binary phase diagrams of diverse types of amines and their aqueous solutions are assessed in order to demonstrate the main features of the thermodynamic and fluid-phase behavior.     

Role of Perceived Importance in Intergroup Contact.

Furthering G. W. Allport's (1954) contentions for optimal contact, the authors introduce a new construct: the perceived importance of contact. They propose that perceived importance is the best proximal predictor of contact's reduction of prejudice. If individuals have opportunities for contact at work or in the neighborhood, their chances to have intergroup acquaintances and friends increase. Intergroup contact among acquaintances and friends can be perceived as more or less important, which in turn determines intergroup evaluations. A 1st study shows that the new measure of perceived importance is indeed distinct from established quantity and quality indicators. The results are cross-validated in a 2nd study that also sheds light on the meaning of importance. In 3rd and 4th studies, structural equation analyses and a meta-analysis support the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

Treatment of hypertension in nondiabetic renal disease

To clarify whether long-term impaired glucose tolerance (IGT) is associated with dysfunction of peripheral and autonomic nerves, age-matched men with IGT and diabetes mellitus were followed prospectively for 12-15 years, when peripheral and autonomic nerve function was assessed. The patients comprised four subgroups: (1) 51 IGT subjects (duration of IGT at least 12-15 years); (2) 35 diabetic patients, with IGT 12-15 years ago, who later developed diabetes; (3) 34 diabetic patients, duration of diabetes at least 12-15 years; and (4) 62 age-matched non-diabetic control subjects. Mean age of the whole study population was 61 +/- 2 years (mean +/- SD), not different in the four groups. Peripheral nerve function tests included nerve conduction velocities, amplitudes, distal latencies, F-reflexes, and sensory perception thresholds for heat, cold, and vibration. Autonomic nerve function tests included the heart rate reaction during deep breathing (expiration to inspiration ratio) and to tilt (acceleration and brake indices). Despite 12-15 years of IGT, peripheral nerve function did not differ between IGT and control subjects, whereas autonomic nerve function deviated; an abnormal expiration to inspiration ratio (a sign of vagal nerve dysfunction) was significantly more common (15/51 versus 5/62; p < 0.01) in IGT than in control subjects. Diabetic patients (groups 2 and 3) showed lower conduction velocities (in general 2-4 m s-1 lower) than IGT and control subjects in all tested nerves. In conclusion, diabetes but not IGT, is associated with peripheral nerve dysfunction.     

Matter Wave Solitons at Finite Temperatures

We consider the dynamics of a dark soliton in an elongated harmonically trapped Bose-Einstein condensate. A central question concerns the behavior at finite temperatures, where dissipation arises due to the presence of a thermal cloud. We study this problem using coupled Gross-Pitaevskii and N-body simulations, which include the mean field coupling between the condensate and thermal cloud. We find that the soliton decays relatively quickly even at very low temperatures, with the decay rate increasing with rising temperature.     

Microscale wear of vitrified abrasive materials

The study of bonding hard materials such as aluminium oxide and cubic boron nitride (cBN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce components with very high tolerances. It is expected that the same grinding wheel be used for both rough and finish machining operations. Therefore, the grinding wheel, and in particular its bonding system, is expected to react differently to a variety of machining operations. In order to maintain the integrity of the grinding wheel, the bonding system that is used to hold abrasive grains in place will react differently to forces that are placed on individual bonding bridges. This paper examines the role of vitrification heat treatment on the development of strength between abrasive grains and bonding bridges, and the nature of fracture and wear in vitrified grinding wheels that are used for precision grinding applications.