Synthesis and Characterization of A Tetrathiafulvalene-Salphen Actinide Complex

A new tetrathiafulvalene-salphen uranyl complex has been prepared. The system was designed to study the electronic coupling between actinides and a redox active ligand framework. Theoretical and experimental methods - including DFT calculations, single crystal X-ray analysis, cyclic voltammetry, NMR and IR spectroscopies - were used to characterize this new uranyl complex.Office of Basic Energy Sciences, U. S. Department of Energy (DOE) DE-FG02-01ER15186Ministry of Education, Science and TechnologyHeavy Element Chemistry Program by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of EnergyGlenn T. Seaborg InstituteNational Nuclear Security Administration of U.S. Department of Energy DE-AC52-06NA25396Chemistr

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Quantitative 18F-AV1451 Brain Tau PET Imaging in Cognitively Normal Older Adults, Mild Cognitive Impairment, and Alzheimer's Disease Patients

Recent developments of tau Positron Emission Tomography (PET) allows assessment of regional neurofibrillary tangles (NFTs) deposition in human brain. Among the tau PET molecular probes, 18F-AV1451 is characterized by high selectivity for pathologic tau aggregates over amyloid plaques, limited non-specific binding in white and gray matter, and confined off-target binding. The objectives of the study are (1) to quantitatively characterize regional brain tau deposition measured by 18F-AV1451 PET in cognitively normal older adults (CN), mild cognitive impairment (MCI), and AD participants; (2) to evaluate the correlations between cerebrospinal fluid (CSF) biomarkers or Mini-Mental State Examination (MMSE) and 18F-AV1451 PET standardized uptake value ratio (SUVR); and (3) to evaluate the partial volume effects on 18F-AV1451 brain uptake.Methods: The study included total 115 participants (CN = 49, MCI = 58, and AD = 8) from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Preprocessed 18F-AV1451 PET images, structural MRIs, and demographic and clinical assessments were downloaded from the ADNI database. A reblurred Van Cittertiteration method was used for voxelwise partial volume correction (PVC) on PET images. Structural MRIs were used for PET spatial normalization and region of interest (ROI) definition in standard space. The parametric images of 18F-AV1451 SUVR relative to cerebellum were calculated. The ROI SUVR measurements from PVC and non-PVC SUVR images were compared. The correlation between ROI 18F-AV1451 SUVR and the measurements of MMSE, CSF total tau (t-tau), and phosphorylated tau (p-tau) were also assessed.Results:18F-AV1451 prominently specific binding was found in the amygdala, entorhinal cortex, parahippocampus, fusiform, posterior cingulate, temporal, parietal, and frontal brain regions. Most regional SUVRs showed significantly higher uptake of 18F-AV1451 in AD than MCI and CN participants. SUVRs of small regions like amygdala, entorhinal cortex and parahippocampus were statistically improved by PVC in all groups (p < 0.01). Although there was an increasing tendency of 18F-AV-1451 SUVRs in MCI group compared with CN group, no significant difference of 18F-AV1451 deposition was found between CN and MCI brains with or without PVC (p > 0.05). Declined MMSE score was observed with increasing 18F-AV1451 binding in amygdala, entorhinal cortex, parahippocampus, and fusiform. CSF p-tau was positively correlated with 18F-AV1451 deposition. PVC improved the results of 18F-AV-1451 tau deposition and correlation studies in small brain regions.Conclusion: The typical deposition of 18F-AV1451 tau PET imaging in AD brain was found in amygdala, entorhinal cortex, fusiform and parahippocampus, and these regions were strongly associated with cognitive impairment and CSF biomarkers. Although more deposition was observed in MCI group, the 18F-AV-1451 PET imaging could not differentiate the MCI patients from CN population. More tau deposition related to decreased MMSE score and increased level of CSF p-tau, especially in ROIs of amygdala, entorhinal cortex and parahippocampus. PVC did improve the results of tau deposition and correlation studies in small brain regions and suggest to be routinely used in 18F-AV1451 tau PET quantification

Conversion Discriminative Analysis on Mild Cognitive Impairment Using Multiple Cortical Features from MR Images

Neuroimaging measurements derived from magnetic resonance imaging provide important information required for detecting changes related to the progression of mild cognitive impairment (MCI). Cortical features and changes play a crucial role in revealing unique anatomical patterns of brain regions, and further differentiate MCI patients from normal states. Four cortical features, namely, gray matter volume, cortical thickness, surface area, and mean curvature, were explored for discriminative analysis among three groups including the stable MCI (sMCI), the converted MCI (cMCI), and the normal control (NC) groups. In this study, 158 subjects (72 NC, 46 sMCI, and 40 cMCI) were selected from the Alzheimer's Disease Neuroimaging Initiative. A sparse-constrained regression model based on the l2-1-norm was introduced to reduce the feature dimensionality and retrieve essential features for the discrimination of the three groups by using a support vector machine (SVM). An optimized strategy of feature addition based on the weight of each feature was adopted for the SVM classifier in order to achieve the best classification performance. The baseline cortical features combined with the longitudinal measurements for 2 years of follow-up data yielded prominent classification results. In particular, the cortical thickness produced a classification with 98.84% accuracy, 97.5% sensitivity, and 100% specificity for the sMCI–cMCI comparison; 92.37% accuracy, 84.78% sensitivity, and 97.22% specificity for the cMCI–NC comparison; and 93.75% accuracy, 92.5% sensitivity, and 94.44% specificity for the sMCI–NC comparison. The best performances obtained by the SVM classifier using the essential features were 5–40% more than those using all of the retained features. The feasibility of the cortical features for the recognition of anatomical patterns was certified; thus, the proposed method has the potential to improve the clinical diagnosis of sub-types of MCI and predict the risk of its conversion to Alzheimer's disease

SPECTROSCOPIC CHARATERIZATION OF ThF AND THE LOW-LYING STATES OF ThF+^+

Author Institution: Department of Chemistry, Emory University, Atlanta, GA 30322Theoretical calculations predict that internal electric fields as high as 90 GV/cm can be attained by polarizing the $^3\Delta_1$ state of ThF$^+$, 010502/1 (2008). \textit{"Prospects for an electron electric-dipole moment search in metastable ThO and ThF+"}} Consequently, this ion is of interest for investigation of the dipole moment of the electron. However, spectroscopic data have not been reported previously for ThF or ThF$^+$. We have used laser induced fluorescence and resonantly enhanced two-photon ionization to examine ThF. Multiple electronic transitions were observed in the 19530-21300 \wn range. Rotationally resolved data have been obtained, and the ground state is shown to be X$^2\Delta$_3_/_2. Pulsed field ionization - zero electron kinetic energy spectra have been recorded for the ThF+ cation. Vibronic progressions of the X$^1\Sigma^+$ and excited $^3\Delta$ states have been identified. The term energy for the $^3\Delta_1$ state was found to be T$_0$=330 \wn. Details of the experiments and spectroscopic constants for ThF and ThF$^+$ will be reported

A NEGATIVE ION PHOTOELECTRON SPECTROSCOPIC AND COMPUTATIONAL STUDY OF CrV AND MoV

Author Institution: Department of Chemistry, University of Minnesota; Minneapolis, MN 55455The heteronuclear diatomic metal ions CrV$^{-}$ and MoV$^{-}$ were investigated using negative ion photoelectron spectroscopy. These bare, heteronuclear group 5 and 6 transition metal dimers allow the study of multiple metal-metal bonding free of ligand effects. The photoelectron spectra, obtained at 488 nm with an instrumental resolution of about 5 meV (40 cm$^{-1}$), provide measurements of the electron affinities, vibrational frequencies for both the anion and neutral states, bond length changes upon electron detachment, excited electronic state energies and spin-orbit splittings. The CrV$^{-}$ and MoV$^{-}$ spectra display transitions to the multiply-bonded $^{2}\Delta$ $(d\pi)^{4}(d\delta)^{3}(d\sigma)^{2}(s\sigma)^{2}$ ground states of the neutral molecules and to several excited states. Addition of an electron to the vacant $\sigma^{*}$ orbital gives the $^{3}\Delta$ anion, which is found to be the ground state of CrV$^{-}$ but a low lying excited state of MoV$^{-}$. Addition of a d$\delta$ electron yields the $^{1}\Sigma^{+}$ MoV$^{-}$ ground state. Density functional theory calculations of the anions and neutrals were performed to help elucidate the spectroscopic assignments and observed periodic trends

A NEGATIVE ION PHOTOELECTRON SPECTROSCOPIC AND COMPUTATIONAL STUDY OF Mo2_{2} AND Mo2−_{2}^{-}

Author Institution: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455We report the 488 and 514 nm anion photoelectron spectra of Mo$_{2}^{-}$. Neutral Mo$_{2}$ has been described in recent $ab$ $initio$ studies as having a bond order of six, predicted to be the highest of any homonuclear diatomic, exceeding even that of Cr$_{2}$(five). The photoelectron spectrum of Mo$_{2}^{-}$confirms the previously measured vibrational frequency of gas phase Mo$_{2}$ and displays transitions to vibrational levels up to v=7 in its $^{1}\Sigma_{g}^{+}$ ground state. The electron affinity of Mo$_{2}$ is measured to be 0.732 $\pm$ 0.010 eV. The Mo$_{2}^{-}$ ground state is assigned as a $^{2}\Sigma_{u}^{+}$ state, in which the extra electron occupies a formally antibonding $\sigma_{u}$ orbital of primarily 5$s$ atomic parentage. A Franck-Condon analysis of the vibrational band intensities indicates a change in the equilibrium bond length of only 0.03 $\pm$ 0.02 \AA $$ upon electron detachment. These results, and the similar vibrational frequencies measured for Mo$_{2}$ and Mo$_{2}^{-}$, suggest that the anion HOMO is essentially nonbonding. Weak photodetachment transitions to excited states of Mo$_{2}$ lying within 1.2 eV of its ground state are also observed. DFT calculations using the BPW91/SDD method show good agreement with experiment for the electron affinity of Mo$_{2}$ and the bond lengths in the anion and neutral molecule ground states. It is hoped that these spectroscopic results will motivate and assist high level theoretical studies of the Mo$_{2}^{-}$ anion

THE PFI-ZEKE SPECTRUM OF HfF+^+, IN SUPPORT OF FUNDAMENTAL PHYSICS

Author Institution: Department of Chemistry, Emory University, Atlanta, GA 30322The HfF$^+$ cation has been identified as a molecule with favorable properties for investigation of the dipole moment of the electron. The ion is predicted to have a $^1\Sigma^+$ ground state, but the state of greatest interest is the low-lying $^3\Delta_1$ state, which correlates with Hf$^+$(6s5d)F$^-$. A high internal electric field may be generated when the $\Omega$=1 state is polarized by a modest external field. In the present work, spectroscopic data for the ground and low-lying states HfF$^+$ have been obtained using the technique of pulse field ionization - zero electron kinetic energy (PFI-ZEKE) spectroscopy. Sequential two-photon excitation was used, with the first photon set to excite a transition near 28593 \wn. This previously unreported band was used as it is at slightly less than half of the ionization energy (IE), and therefore not subject to one-color, two-photon ionization. PFI-ZEKE spectra were recorded for the levels X$^1\Sigma^+$ (v=0-6), $^3\Delta_1$ (v=0-3), $^3\Delta_2$ (v=0-3), and $^3\Delta_3$ (v=0,1). Rotational resolution was achieved using single rotational line excitation of the intermediate state. The IE for HfF was found to be 59477 \wn. Term energies and molecular constants for the ground and low-lying states of HfF$^+$ will be reported