Solvent Extraction of U(VI) by Calix[6]arenes

Abstract

This paper focuses on the solvent extraction of U(VI) traces by 1,3,5‐OMe‐2,4,6‐OCH₂CONHOH‐p‐tert‐butylcalix[6]arene (LH₃). The global extraction equation of U(VI) has been established. The complex formed in the organic phase is (UO₂)(LH) with an apparent extraction constant equal to 7.1×10^?5 M (I=0.04 M). Distribution data show that LH₃ efficiently extracts U(VI) from NaNO₃ media at pH 5 and that the stripping of U(VI) can be achieved in nitric acid solutions. Finally a comparison with previous results obtained with the 1,3,5‐OMe‐2,4,6‐OCH₂COOH‐p‐tert‐butylcalix[6]arene (L′H₃) shows that the hydroxamate groups are as efficient as the carboxylate ones for uranyl extraction.     

Influence of Phase Modifiers on the Degradation of Tri-n-octylamine/dodecane Extracting Mixture by an Acidic Solution of Vanadium (V)

The kinetics of degradation of a mixture of tri-n-octylamine (extractant) and various alcoholic phase modifiers in n-dodecane in contact with acidic aqueous sulfate solutions containing vanadium (V) has been investigated. The nature of the modifier influences the kinetics of degradation and an improvement of the resistance against the chemical degradation is obtained when secondary alcohol (2-nonanol) or tertiary alcohols such as 9-octyl-9-heptadecanol are used as phase modifiers instead of 1-tridecanol. For instance, the kinetic constant of degradation is divided by one half when 9-octyl-9-heptadecanol is used as phase modifier instead of 1-tridecanol. On the contrary, the alcohols containing aromatic substituents or fluorine atoms are responsible for an increase of the chemical degradation of the extraction solvent.     

Altered systemic iron metabolism in Parkinson's disease

Iron deposition in the substantia nigra in Parkinson's disease has been associated with an increase in lactoferrin receptors and a reduction in ferritin concentration. This accumulation of iron in the brain may accelerate free radical formation, lipid peroxidation, and neuronal death. Remarkably, there are few data available concerning systemic iron metabolism in Parkinson's disease. We measured total iron binding capacity and circulating iron, ferritin, transferrin, and transferrin receptors; calculated transferrin saturation; and estimated dietary iron intake in patients with idiopathic Parkinson's disease and in controls. Concentrations of circulating iron, ferritin, and transferrin as well as total iron binding capacity and transferrin saturation were significantly lower in patients than controls. There were no differences in transferrin receptors or dietary intake of iron. The decrease in levels of systemic ferritin and transferrin and the total iron binding capacity parallels observations in a Parkinson's disease brain, but the reductions in serum iron concentrations and transferrin saturation do not, and were unexpected. These results suggest the existence of a defect in the systems that regulate the synthesis of the major proteins of iron metabolism in the liver as well as the brain in Parkinson's disease that may, over time, expedite entry of iron into the brain and decrease iron in the extracellular compartment.     

Systemic iron metabolism and mortality from Parkinson's disease

Six measures of systemic iron metabolism were used to predict mortality among 103 patients with Parkinson's disease and 353 controls followed in a longitudinal study. Adjusting for gender, education, ethnicity, presence of dementia, and extrapyramidal signs, transferrin receptor concentration was strongly associated with mortality in patients with PD but not controls. This increase in serum transferrin receptor concentration before death suggests that the previously observed perturbation in iron metabolism continues throughout the disease course.     

Automated swept-angle bistatic scattering measurements usingcontinuous wave radar

The establishment of the IEEE Electromagnetic Modeling Software Committee and the Department of Defense sponsored Electromagnetic Code Consortium indicates the electromagnetics community is interested in validating general electromagnetic modeling software. An important part of this validation is obtaining reliable bistatic scattering measurements on canonical scatterers. The author describes a simple system well suited for such measurements. The system is capable of measuring bistatic scattering from near backscatter through forward scatter. At X-band frequencies, scattering levels of -50 dBsm in the backscattering region and -20 dBsm near forward scatter can be measured to an accuracy of ±1 dB. This fully automated indoor system fixes the target and direction of illumination and sweeps the receive antenna to collect data as a direct function of bistatic angle. A broad band, coherent, continuous wave radar is used to obtain both amplitude and phase of the component of the total field aligned with the receive antenna polarization. The system design, calibration procedures, and measurement accuracy are considered     

Cognitive and affective functioning in Parkinson''s disease patients with lateralized motor signs

OBJECTIVE: This study aimed to compare recordings of the electrically evoked whole nerve action potential (EAP) made using the reverse telemetry system of the Nucleus CI24M device with those recorded from individuals who use the Ineraid cochlear implant system. STUDY DESIGN: Data were collected in a prospective fashion from Nucleus CI24M cochlear implant users and compared with retrospective data collected from patients who use the Ineraid device. SETTING: All data were collected at the Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics. PATIENTS: Data are reported from 8 patients who use the Nucleus CI24M cochlear implant and 20 patients who use the Ineraid cochlear implant system. INTERVENTIONS: The interventions described in this study were diagnostic in nature. MAIN OUTCOME MEASURES: EAP growth and refractory recovery data are reported. EAP thresholds recorded from patients who use the Nucleus CI24M device also are compared with behavioral thresholds for the stimulus used to evoke the EAP as well as the stimulation levels needed to program the speech processor. RESULTS: EAP morphology, growth, and refractory recovery functions recorded using the Nucleus CI24M reverse telemetry system compared favorably with similar measures recorded from Ineraid cochlear implant users. CONCLUSIONS: Reasonable EAP responses can be recorded using the Nucleus CI24M device. More data are needed to determine whether the information about neural responsiveness available with this device will be clinically useful.     

Carcinomas of Bartholin''s gland. Histogenesis and the etiological role of human papillomavirus

In this study, we examine 10 primary carcinomas of Bartholin's gland, including seven squamous carcinomas, two adenoid cystic carcinomas, and one adenocarcinoma, as well as four non-neoplastic Bartholin's gland. Six of seven squamous cell carcinomas contained human papillomavirus (HPV) type 16 DNA detectable by the polymerase chain reaction; one of these demonstrated HPV type 16 by in situ hybridization. The two adenoid cystic carcinomas, the adenocarcinoma, and the non-neoplastic Bartholin's gland epithelium showed no evidence of HPV DNA by polymerase chain reaction or in situ hybridization. A panel of eight antibodies (Cam 5.2, B72.3, CEA, EMA, MCA, Lewis X, ER, and PR) demonstrate that the squamous, transition zone, duct, acinar, and myoepithelial cells or Bartholin's gland are antigenically distinct, and are similar to those reported in analogous areas of the uterine cervix. Squamous carcinoma and adenocarcinomas of Bartholin's gland are antigenically similar, and seem to arise from the transition zone of the Bartholin's gland duct. The origin of adenoid cystic carcinomas is more difficult to determine; it is distinct from squamous and adenocarcinomas and seems more likely to arise from myoepithelial cells. We conclude that adenocarcinoma and squamous cell carcinoma of Bartholin's gland arise in the transition zone of Bartholin's gland, which is similar to the transition zone of the uterine cervix. We also show that HPV is associated with Bartholin's gland carcinoma and may play a role in the genesis of malignancy.     

Snell's law applied to finite surfaces

Snell's law of reflection applies to a plane wave incident on an infinite surface. For finite surfaces the size of the surface, the angle of incidence, and the polarization of the incident wave all contribute to deviations from Snell's law. An eigenfunction expansion for the scattering pattern of a perfectly conducting strip and experimental bistatic scattering measurements of rectangular plates are used to verify the deviations. Physical optics calculations also predict these deviations and are used to provide a physical explanation for the deviations     

Towards chip prototyping: a model for droplet formation at both T and X-junctions in dripping regime

Segmented flows in both T and X-junction glass microchannels are investigated. The effective pressure domain of use of the microchips are compared for two chemical systems. After studying the flow patterns and current empirical equations proposed in the literature, a new empirical equation is validated for both T and X-junctions allowing the prediction of not only the domain of use of the microchip in terms of flow rates knowing the viscosities of the two phases but also the droplets diameter, volume, spacing, and specific interfacial area. Specific interfacial area could be optimized using the model within our specific microsystems, and a maximum of 10,000 m^?1 is determined. Ensuing the definition of the model, several insights in the way to optimize segmented flows for different purposes are discussed, i.e., for the production of monodisperse populations of droplets and mass transfer optimization.