Preparation, stability, and structural characterization of plutonium(VII) in alkaline aqueous solution.

A freshly prepared solution of Pu(VI) in 2 M NaOH was oxidized to Pu(VII), via ozonolysis, while simultaneously collecting X-ray absorption spectra. Analyses of the XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) data, acquired throughout the in situ experiments, show a dioxo coordination environment for Pu(VI), PuO(2)(2+), typical for it and the hexavalent actinyl species of U and Np, and its evolution into a tetraoxo-coordination environment for Pu(VII), PuO(4)(-), like that known for Np(VII). The EXAFS data provide average Pu-O distances of 1.79(1) and 1.88(1) Å, respectively. The second coordination shells, also fit as O atoms, provide Pu-O distances of 2.29-2.32 Å that are independent of the Pu oxidation state. The coordination numbers for the distant O atoms in sums with those for the nearest O atoms are consistent with 6-O environments for both Pu(VI) and Pu(VII) ions in accordance with their previously proposed speciation as [Pu(VI)O(2)(OH)(4)](2-) and [Pu(VII)O(4)(OH)(2)](3-), respectively. This solution speciation accounts precisely for the Pu(VI) and Pu(VII) coordination environments reported in various solid state structures. The Pu(VII) tetraoxo-dihydroxo anion was found to have a half-life of 3.7 h. Its instability is attributed to spontaneous reduction to Pu(VI) and not to a measurable extent of disproportionation. We found no direct evidence for Pu(VIII) in the X-ray data and, furthermore, the stoichiometry of the oxidation of Cr(III) by Pu is consistent with that expected for a valence-pure Pu(VII) preparation by ozonation and, in turn, stoichiometrically equivalent to the established Np(VII)/Cr(III) redox reaction.

Long-term outcomes confirm the superior efficacy of extended Heller myotomy with Toupet fundoplication for achalasia.

BACKGROUND: The standard Heller myotomy (SM) for achalasia extends 1 to 2 cm on to the stomach. The authors perform an extended myotomy (EM) (>3 cm) with the goal of reducing postoperative dysphagia. This study examines the long-term efficacy and durability of EM compared with SM. METHODS: Patients with achalasia who underwent a laparoscopic Heller myotomy were identified from a prospective database that includes symptom evaluation and results of esophageal functional studies. From September 1994 to August 1998, the authors performed SM with Dor fundoplication, and from September 1998 through 2003, they performed EM with Toupet fundoplication. In 2001, they performed a telephone survey of all available patients. This was repeated in 2005 for the EM group. The survey included scales of symptom frequency (0 [never], 1 [once per month], 2 [once per week], 3 [once per day], 4 [more than once per day]) and severity (0 [no symptoms] to 10 [symptoms equal to preoperative state]) as well as the need to undergo postoperative intervention for dysphagia. RESULTS: For this study, 52 patients underwent SM with Dor fundoplication (median follow-up period, 46 +/- 24 months), and 63 patients underwent EM with Toupet fundoplication (median follow-up period, 45 +/- 17 months. Postoperative dysphagia severity was significantly better in the EM group (4.8 +/- 2.3 vs 3.1 +/- 2.6; p < 0.005). There was no significant difference in postoperative heartburn frequency, esophageal acid exposure, or lower esophageal sphincter pressure. In the SM group, 9 patients (17%) required reintervention for dysphagia: 14 endoscopic interventions for 5 patients (10%) and reoperation for 4 patients. Three patients (5%) in the EM group required reintervention for dysphagia: one endoscopic intervention each and no reoperations (p < 0.05). A total of 30 patients in the EM group were contacted in both 2001 (median follow-up period, 19 +/- 11 months) and 2005 (median follow-up period, 63 +/- 10 months). There was no significant change over time in dysphagia severity (2.6 +/- 1.9 vs 3.7 +/- 2.0; p = 0.19). CONCLUSIONS: For the treatment of achalasia, EM with Toupet fundoplication provides excellent durable dysphagia relief that is superior to SM with Dor fundoplication.

Correlated electrons in the Eu-exchanged Preyssler anion [EuP(5)W(30)O(110)](n-).

The Eu-encrypted Preyssler anion, [EuP5W30O110]n-, demonstrates unusual electronic properties as a function of applied potenial. The Preyssler anion itself, when exchanged with a nonredox active trivalent ion such as La3+, is electroactive in acidic solution, reversibly accepting up to 10 electrons under reducing conditions. Encrypted Eu, which is trivalent at rest potential, is reduced concomitantly with the framework. The details of this reduction are probed with Eu L3-XANES, coulometry, and magnetic susceptibility. The results are interpreted in terms of a bonding interaction between the Eu f-states and the W-O framework band, facilitated by the crossing of the framework Fermi level with the localized states. Such behavior has been previously observed in intermediate-valent and correlated-electron systems. The observation of such behavior in an isolated cluster opens the door for new avenues of research into correlated-electron behavior.

Coordination of rare-earth elements in complexes with monovacant Wells-Dawson polyoxoanions.

The alpha-1 and alpha-2 isomers of the monovacant Wells-Dawson heteropolyoxoanion [P(2)W(17)O(61)](10-) are complexants of trivalent rare-earth (RE) ions and serve to stabilize otherwise reactive tetravalent lanthanide (Ln) and actinide (An) ions in aqueous solution. Aspects of the bonding of Ln ions with alpha-1-[P(2)W(17)O(61)](10-) and alpha-2-[P(2)W(17)O(61)](10-) were investigated to address issues of complex formation and stability. We present structural insights about the Ln(III) coordination environment and hydration in two types of stoichiometric complexes, [Ln(alpha-1-P(2)W(17)O(61))](7-) and [Ln(alpha-2-X(2)W(17)O(61))(2)](17-) (for Ln identical with Sm, Eu, Lu; X identical with P, As). The crystal and molecular structures of [(H(2)O)(4)Lu(alpha-1-P(2)W(17)O(61))](7-) (1) and [Lu(alpha-2-P(2)W(17)O(61))(2)](17-) (2) were solved and refined through use of single-crystal X-ray diffraction. The crystallographic results are supported with corresponding insights from XAFS (X-ray absorption fine structure) for a series of nine solid-state complexes as well as from optical luminescence spectroscopy of the Eu(III) analogues in aqueous solution. All the Ln ions are eight-coordinate with oxygen atoms in a square antiprism arrangement. For the 1:1 stoichiometric Ln/alpha-1-[P(2)W(17)O(61)](10-) complexes, the Ln ions are bound to four O atoms of the lacunary polyoxometalate framework in addition to four O atoms from solvent (water) molecules as [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-). This structure (1) is the first of its kind for any metal complex of alpha-1-[P(2)W(17)O(61)](10-), and the data indicate that the general stoichiometry [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-) is maintained throughout the lanthanide series. For the 1:2 stoichiometric Ln/alpha-2-[X(2)W(17)O(61)](10-) complexes, no water molecules are in the Ln-O(8) coordination sphere. The Ln ions are bound to eight O atoms-four from each of two heteropolyanions-as [Ln(alpha-2-X(2)W(17)O(61))(2)](17-). The average Ln-O interatomic distances decrease across the lanthanide series, consistent with the decreasing Ln ionic radius.

Research on chronic, low-level exposure to formaldehyde: implications for neuropsychological assessment.

Findings from empirical research serve as the foundation for neuropsychological assessment of individuals suspected of exposure to formaldehyde. Insofar as conclusions regarding causal relationships between exposure and neuropsychological deficits are based on research methodologies that are reliable, findings can be informative. Unfortunately, existing research is not rooted in sound methodology and findings may mislead rather than enlighten clinicians. Two prominent shortcomings in formaldehyde research are discussed: selection bias in recruitment of research participants and unreliability of participant recall for obtaining data on important background variables and exposure levels. Selected examples illustrate the influence of these shortcomings on research showing a causal relationship between long-term, low-level exposure to formaldehyde and chronic neurobehavioral deficiencies. The implications of these weaknesses for assessment of individual patients are discussed.

A sharp cutting liposuction cannula for gynecomastia.

Liposuction is often used for the treatment of gynecomastia. Blunt liposuction cannulas can remove the fat but are not very effective in fibrous breast tissue, which requires open excision. Ultrasound-assisted lipoplasty has been advocated for gynecomastia because it effectively removes the fat from fibrous areas. An alternative treatment is a sharp cutting liposuction cannula that easily penetrates and removes the fibrous breast tissue along with the fatty component. The early experience of 22 surgeons who used this cannula in 88 cases of gynecomastia is reported. For 19 of the 22 surgeons, liposuction with sharp cutting cannulas alone gave a satisfactory result in 81% of their patients.

Effect of information about odor on causal ascriptions for illness.

The effect of information about detection of an odor on causal ascriptions for illness was investigated. In four different scenarios perceptions regarding the cause of a hypothetical symptomatic experience were compared for events described with and without an odor. Participants (N = 106) were asked to imagine themselves becoming ill after engaging in several common experiences, including pumping gasoline at a service station. In two scenarios participants read that they smelled an offensive odor while pumping the gasoline whereas in two other scenarios no information about an odor was provided. Further, information about gasoline described with or without odor was presented either early or late in the stimulus paragraphs. All participants then responded to questions including an open-ended question asking them to make causal attributions for their illness. Participants in the odor-suggested group ascribed the cause of illness more frequently to gasoline and perceived the probability of other potential causes as lower than did participants in the nonodor suggested group. Findings suggest that peoples' implicit theories about toxicity contain causal connections between malodorous stimuli and illness. The implications of implicit theories for perception of illness are discussed.

Response bias in plaintiffs' histories.

This study investigated response bias in self-reported history of factors relevant to the assessment of traumatic brain injury, toxic brain injury and related emotional distress. Response bias refers to systematic error in self-report data. A total of 446 subjects (comprising 131 litigating and 315 non-litigating adults from five locations in the United States) completed a symptom questionnaire. Data were obtained from university faculty and students, from patients in clinics specializing in physiatry neurology, and family medicine, and from plaintiffs undergoing forensic neuropsychological evaluations. Comparisons were made for litigant and non litigant ratings of their past and current cognitive and emotional functioning, including life in general, ability to concentrate, memory, depression, anxiety, alcohol, drugs, ability to work or attend school, irritability, headaches, confusion, self-esteem, and fatigue. Although there is no basis for hypothesizing plaintiffs to be healthier than the general population, plaintiffs rated their pre-injury functioning superior to non-plaintiffs. These findings suggest that response biases need to be taken into account by forensic examiners when relying on litigants' self-reports of pre-injury status.

Neurotoxicity of chronic low-dose exposure to organic solvents: a skeptical review.

The health effects of long-term, low-level exposure to organic solvents have been studied for many years. While the volume of literature is great, definitive conclusions regarding chronic neurobehavioral effects of environmental exposure are premature. Methodological shortcomings in research preclude confidence in studies allegedly supporting a causal link between chronic low-dose solvent exposure and lasting neurobehavioral deficits. In this article, the shortcomings reviewed include selection bias in recruitment of research subjects, overreliance on subjective recall in determining levels and duration of exposure, between-study variability in kinds of solvents examined, variability in tests selected to assess neurobehavioral functioning, and diversity in reported findings. The implications of these for characterizing the state of organic solvent research are discussed.

The implications of limitations in hydrocarbon research for neuropsychological assessment.

As neuropsychologists are involved increasingly in the neuropsychological assessment of individuals reporting both acute and long-term exposure to hydrocarbons, the value of research for providing guidance also increases. Research findings inform neuropsychologists about likely neuropsychological deficits given certain intensity and duration of exposure and about neuropsychological tests most appropriate for detecting hydrocarbon-induced deficits. Although high-dose events are associated with neuropsychological deficits, methodological weaknesses in the existing research impede a consensus on the implications of low-dose exposures in humans. Three flaws inherent in research on low-dose hydrocarbon exposures and their implications for neuropsychological assessment of individuals are discussed: Selection bias in recruitment of research participants, biased recall of research participants, and between-study variation in neuropsychological tests and results. Because they undermine the reliability and validity of existing research, lack of awareness of these weaknesses may interfere with unbiased assessment of individual patients suspected of hydrocarbon-induced neuropsychological deficits. Examples from the social-cognitive psychological literature contribute to understanding how misleading research findings can lead experts to form expectancies that bias assessment of individuals.

Response bias in self-reported history of plaintiffs compared with nonlitigating patients.

Response bias refers to systematic error in the data produced by patients or research subjects, e.g., due to erroneous recall or reporting. In forensic settings, response bias appears to be associated with the nature of the proceedings. The present study tested whether patients in litigation exhibit different response patterns than nonlitigating patients when asked about their preinjury problems. 34 litigants and 80 nonlitigants rated various areas of cognitive and emotional functioning as problematic in the past and currently. The primary finding was that plaintiffs reported pre-injury functioning superior to that of controls. These findings suggest the need for caution in inferences that litigants are either reliable or deceitful because response biases may affect self-reports in a misleading fashion.

Neurotoxicity of chronic low-level exposure to organic solvents: caveats for applied neuropsychologists.

Research findings on the neuropsychological consequences of chronic low-level exposure to organic solvents are equivocal. Because methodological weaknesses cast doubt on some empirical publications that report causal links between occupational exposure and irreversible neuropsychological deficits, findings can mislead rather than inform neuropsychological assessment. Empirical articles often do not provide enough information to support the conclusions offered or to evaluate the reasoning by which the conclusions were reached. This article discusses some prototypical weaknesses in empirical articles and illustrates these weaknesses with selected examples. The contribution that neuropsychologists can make to improve the quality of research is discussed.

Neurotoxic complaint base rates of personal injury claimants: implications for neuropsychological assessment.

This study reports base rate data for 113 family practice patients with no history of head trauma or toxic exposure, 68 family practice patients with a history of head trauma or toxic exposure, and 156 personal injury claimants with no history of toxic exposure or head trauma who presented for a psychological evaluation due to emotional distress. Personal injury claimants reported suffering from significantly more neurotoxic and neuropsychologic symptoms than subjects with a reported history of head trauma and/or toxic exposure. The authors urge that evaluating psychologists consider the base rate of these symptoms in litigating populations and use caution in relying on self-reported symptoms as evidence of injury when patients are in litigation.

Human response to traumatic events: an integration of counterfactual thinking, hindsight bias, and attribution theory.

In documenting cognitive processes underlying persons' reactions to negative events, counterfactual thinking, hindsight bias, and attribution theory focus on distinct, although not unrelated, aspects of human information processing. Counterfactual thinking highlights the cognitive processing undertaken when persons imagine different courses of action that lead to alternative outcomes. Hindsight bias describes the inflated retrospective estimates individuals make regarding event probabilities that come with the advantage of knowledge about outcomes. And attribution theory concerns the affective and behavioral consequences that result from the perceived causes of events. This essay argues that a more comprehensive understanding of the processes underlying human response to traumatic events results from the integration of counterfactual thinking, hindsight bias, and attribution theory into a single model.

Hydroxyapatite augmentation of the anterior portion of the maxilla with a modified transpositional flap technique.

Tunneling as a technique for augmentation of an atrophic maxilla has been described in the literature. The use of this technique has presented several prosthodontic problems, such as diffusion of material into adjacent tissues, incorrect positioning of the material on the ridge, and inadequate ridge height. Use of the transpositional flap technique described by Lew and modified by Williams has been used to overcome these problems. Twenty-five patients were treated with this method during a 30-month period. The patients had worn a maxillary complete denture for at least 5 years and had opposing natural mandibular anterior teeth with unsupported posterior occlusion. Use of the transpositional flap technique was shown to overcome the common prosthodontic problems seen with the tunneling procedure for anterior maxilla augmentation with hydroxyapatite.