Neptunium(V) partitioning to uranium(VI) oxide and peroxide solids

Metaschoepite, [(UO2)8O2(OH)12] x 10H2O, and metastudtite, UO4 x 4H2O, are alteration phases anticipated in a spent nuclear fuel repository following the moist oxidation of UO2 on a geologic time scale. Dissolved concentrations and hence potential mobility of other radionuclides in the fuel, such as the neptunyl cation (NpO2+), will likely be determined by the extent of their partitioning into these U(VI) solids. 237Np is of particular interest due to its potential high mobility and long half-life (2.1 x 10(6) years.) In this study, metaschoepite has been precipitated and subsequently transformed to studtite in the presence of dissolved Np. The metaschoepite and studtite solids that formed initially contained <10 and 6500 ppm Np, respectively. Batch dissolution studies of these solids at pH 6 demonstrate release of Np that exceeds congruent dissolution of U from metastudtite; furthermore, the released Np cation remains in solution. Thus, although the Np partitions into the metastudtite solid initially, it is released to solution over time, indicating that metastudtite is not likely to serve as a host solid for Np incorporation or sorption of the neptunyl cation on long time scales.     

Three-dimensional imaging with optical tweezers

We demonstrate a three-dimensional scanning probe microscope in which the extremely soft spring of an optical tweezers trap is used. Feedback control of the instrument based on backscattered light levels allows three-dimensional imaging of microscopic samples in an aqueous environment. Preliminary results with a 2-mum-diameter spherical probe indicate that features of approximately 200 nm can be resolved, with a sensitivity of 5 nm in the height measurement. The theoretical resolution is limited by the probe dimensions.     

Parental history of hypertension and hostility moderate cardiovascular responses to interpersonal conflict

A parental history of hypertension has been implicated in the development of hypertension, perhaps by virtue of an elevated cardiovascular response to stress. Similarly, hostility has been hypothesized to be linked to cardiovascular disease through cardiovascular hyperreactivity. The interaction of parental history and hostility in moderating cardiovascular response has been infrequently examined, though research suggests the two may be linked through familial factors. The present study examined the cardiovascular response of 98 healthy young adult males categorized as offspring of hypertensive subjects (PH+) or offspring of normotensive subjects (PH-) and as high or low hostile, based on Cook-Medley Hostility scores (HiHo vs. LoHo). Subjects were exposed to either an harassment or non-harassment stressor. Results indicated elevated cardiac output and forearm blood flow responses in PH+/HiHo subjects who were harassed as compared to any other harassed subject and all non-harassed individuals. This hemodynamic response pattern of elevated blood flow suggests a mechanism of hypertensive disease development.     

Working memory capacity and self-regulatory behavior: Toward an individual differences perspective on behavior determination by automatic versus controlled processes.

In the present research, the authors investigated how individual differences in working memory capacity moderate the relative influence of automatic versus controlled precursors on self-regulatory behavior. In 2 studies, on sexual interest behavior (Study 1) and the consumption of tempting food (Study 2), automatic attitudes toward the temptation of interest had a stronger influence on behavior for individuals who scored low rather than high in working memory capacity. Analogous results emerged in Study 3 on anger expression in a provoking situation when a measure of the automatic personality trait of angriness was employed. Conversely, controlled dispositions such as explicit attitudes (Study 1) and self-regulatory goals (Studies 2 and 3) were more effective in guiding behavior for participants who scored high rather than low in working memory capacity. Taken together, these results demonstrate the importance of working memory capacity for everyday self-regulation and suggest an individual differences perspective on dual-process or dual-system theories of human behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aconitum sp. alkaloids: the modulation of voltage-dependent Na+ channels, toxicity and antinociceptive properties

Alkaloids from Aconitum sp., used as analgesics in traditional Chinese medicine, were investigated to elucidate their antinociceptive and toxic properties considering: (1) binding to Na+ channel epitope site 2, (2) alterations in synaptosomal Na+ and Ca2+ concentration ([Na+]i, [Ca2+]i), (3) arrhythmogenic action of isolated atria, (4) antinociceptive and (5) acute toxic action in mice. The study revealed a high affinity group (Ki 1 microM) and a low affinity group (Ki 10 microM) of alkaloids binding to site 2. The compounds of the high affinity group induce an increase in synaptosomal [Na+]i and [Ca2+]i (EC50 3 microM), are antinociceptive (ED50, 25 microg/kg), provoke tachyarrhythmia and are highly toxic (LD50 70 microg/kg), whereas low affinity alkaloids reduce [Ca2+]i, induce bradycardia and are less antinociceptive (ED50 20 mg/kg) and less toxic (LD50 30 mg/kg). These results suggest that the alkaloids can be grouped in Na+ channel activating and blocking compounds, but none of the alkaloids seem to be suitable as analgesics because of the low LD50/ED50 values.