Structure-property relationships of isomeric addition polyimides containing nadimide end groups

Addition polyirnide oligomers with nadimide end groups (I) have been synthesized from 4,4′-oxydiphthalic anhydride and 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride with several isomeric diamines and, nadic anhydride. The low molecular weight amic acid? and corresponding imides were isolated and characterized. Solubility and melt-flow properties of the imide prepolymers were studied to determine the applicability of the resins as adhesives and composite matrices. Thermomechanical transitions of the polymers were obtained by torsional braid analysis. Properties were compared with a similar addition polymer, P13N.      

Role of water temperature in the regulation of water intake.

Performed 3 experiments on small groups (n = 2-6) of thirsty Carworth female albino rats. Cool water suppressed water intake. The suppression was apparent from the 1st min of drinking. Suppression occurred for both short (20-min) and long (100-min) daily drinking sessions, and occurred whether the water was available from a sipper tube or a bowl. When cellular hydration was delayed by giving Ss isotonic saline instead of water, the suppression by cooling was enhanced. Cool-water suppression of water intake appears to be a short-latency satiety mechanism that anticipates cellular and extracellular hydration. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of leader behaviors on subordinate performance and satisfaction: A laboratory experiment with student employees.

Four groups of 12 participants were hired to code videotaped group interactions using the Bales coding system (R. F. Bales, 1950). Each of the 4 groups experienced different leader behaviors of either high or low consideration in conjunction with either high or low initiating structure. Results indicate that subordinates did not perceive the leader manipulations as different but that these manipulations caused differences in quantity and quality of work. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A method for radiation-force localized drug delivery using gas-filled lipospheres

We have developed a method using ultrasound and acoustically active lipospheres (AALs) that might be used to deliver bioactive substances to the vascular endothelium. The AALs consist of a small gas bubble surrounded by a thick oil shell and enclosed by an outermost lipid layer. The AALs are similar to ultrasound contrast agents: they can be nondestructively deflected using ultrasound radiation force, and fragmented with high-intensity ultrasound pulses. The lipid-oil complex might be used to carry bioactive substances at high concentrations. An optimized sequence of ultrasound pulses can deflect the AALs toward a vessel wall then disrupt them, painting their contents across the vascular endothelium. This paper presents results from a series of in vitro and ex vivo experiments demonstrating localization of a fluorescent model drug. In experiments using a human melanoma cell (A2085) monolayer, a specific radiation force-fragmentation ultrasound pulse sequence increased cell fluorescence more than 10-fold over no ultrasound or fragmentation pulses alone, and by 50% over radiation force pulses alone. We observe that dye transfer is limited to cells that are in the region of ultrasonic focus, indicating that the application of radiation force pulses to bring the delivery vehicle into proximity with the cell is required for successful adhesion of the vehicle fragments to the cell membrane. We also demonstrate dye transfer from flowing AALs, both in a mimetic vessel and in excised rat cecum. We believe that this method could be successfully used for drug delivery in vivo.     

Microstructural modification of as-cast NiAl bronze by friction stir processing

The application of friction stir processing (FSP) to a cast NiAl bronze (NAB) material is presented as a means for selective modification of the near-surface layers by converting as-cast microstructures to a wrought condition in the absence of macroscopic shape change. This may enable selective surface hardening of cast components. The complex physical metallurgy of the NAB is reviewed, and microstructure changes associated with FSP for a selected set of processing parameters are examined by optical microscopy (OM) and transmission electron microscopy (TEM) methods. Direct temperature measurement in the stir zone is infeasible and, so, these microstructure changes are used to estimate peak temperatures in the stir zone. The persistence of a Fe₃Al phase (κ _ii) indicates that peak temperatures are below the solvus for this phase, while the presence of transformation products of the β phase, including fine Widmanstätten α, bainite, and martensite, indicates that peak temperatures exceed the eutectoid temperature for the reaction β → α+κ _iii throughout the stir zone.     

An eigenspace projection clustering method for inexact graph matching

In this paper, we show how inexact graph matching (that is, the correspondence between sets of vertices of pairs of graphs) can be solved using the renormalization of projections of the vertices (as defined in this case by their connectivities) into the joint eigenspace of a pair of graphs and a form of relational clustering. An important feature of this eigenspace renormalization projection clustering (EPC) method is its ability to match graphs with different number of vertices. Shock graph-based shape matching is used to illustrate the model and a more objective method for evaluating the approach using random graphs is explored with encouraging results.     

Hexachlorocyclohexanes in the North American atmosphere

Annually integrated air concentrations of alpha- and gamma-hexachlorocyclohexane (HCH) were determined in 2000/2001 at 40 stations across North America using XAD-based passive air samplers to understand atmospheric distribution processes on a continental scale. Elevated levels of gamma-HCH in the atmosphere of the Canadian Prairies are consistent with the ongoing use of lindane as a seed treatment on canola and confirm the feasibility of detecting the agricultural use of a pesticide using long-term integrated passive air sampling. In contrast to gamma-HCH, the atmospheric concentrations of alpha-HCH show a rather uniform distribution across Canada and the United States, which is expected for a chemical with no current use on the continent. Higher levels in the atmosphere over Atlantic Canada can be explained by alpha-HCH evaporating from the waters of the Labrador Current, which is supported bythe chiral composition of alpha-HCH and the temperature dependence of its atmospheric concentrations along the east coast of Canada. Similarly, alpha-HCH is volatilizing from Lake Superior. Atmospheric HCH levels increase with elevation in the Canadian Rocky Mountains. The results suggest that evaporation, in particular from cold water bodies, is an important source of alpha-HCH to the North American atmosphere. Low levels of HCHs in Central America hint at efficient degradation under tropical conditions. Chiral analysis shows that (+)-alpha-HCH is often enriched in air over continental areas and at the Pacific Coast, which is opposite to the enantiomeric enrichment in the proximity to the Great Lakes and the Atlantic Ocean. Passive air sampling is a powerful tool to discern the large-scale variability of semivolatile and persistent organic chemicals in the atmosphere.     

Intrinsic reactivity of carbons to oxygen

The analysis of carbon oxidation data presented in a previous Fuel paper is shown to contain an error, as a result of which the intrinsic reactivity of carbon to oxygen is under-estimated by a factor of between one and four.