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Surface water can affect the properties of metal oxide nanoparticles. Investigations on several systems revealed that nanoparticles have different thermodynamic properties than their bulk counterparts due to adsorbed water on their surfaces. Some thermodynamically metastable phases of bulk metal oxides become stable when reduced to the nanoscale, partially due to interactions between high energy surfaces and surface water. Water adsorption microcalorimetry and high-temperature oxide melt solution calorimetry, low-temperature specific heat calorimetry, and inelastic neutron scattering are used to understand the interactions of surface water with metal oxide nanoparticles. Computational methods, such as molecular dynamics simulations and density functional theory calculations, have been used to study these interactions. Investigations on titania, cassiterite, and alumina illustrate the insights gained by these measurements. The energetics of water on metal oxide surfaces are different from those of either liquid water or hexagonal ice, and there is substantial variation in water interactions on different metal oxide surfaces.
Background: To determine whether exosomal microRNAs (miRNAs) in CSF of patients with FTD can serve as diagnostic biomarkers, we assessed miRNA expression in the Genetic FTD Initiative (GENFI) cohort and in sporadic FTD. Methods: GENFI participants were either carriers of a pathogenic mutation or at risk of carrying a mutation because a first-degree relative was a symptomatic mutation carrier. Exosomes were isolated from CSF of 23 -pre-symptomatic and 15 symptomatic mutation carriers, and 11 healthy non-mutation carriers. Expression of miRNAs was measured using qPCR arrays. MiRNAs differentially expressed in symptomatic compared to pre-symptomatic mutation carriers were evaluated in 17 patients with sporadic FTD, 13 patients with sporadic Alzheimer’s disease (AD), and 10 healthy controls (HCs). Results: In the GENFI cohort, miR-204-5p and miR-632 were significantly decreased in symptomatic compared to pre-symptomatic mutation carriers. Decrease of miR-204-5p and miR-632 revealed receiver operator characteristics with an area of 0.89 [90% CI: 0.79-0.98] and 0.81 [90% CI: 0.68-0.93], and when combined an area of 0.93 [90% CI: 0.87-0.99]. In sporadic FTD, only miR-632 was significantly decreased compared to sporadic AD and HCs. Decrease of miR-632 revealed an area of 0.89 [90% CI: 0.80-0.98]. Conclusions: Exosomal miR-204-5p and miR-632 have potential as diagnostic biomarkers for genetic FTD and miR-632 also for sporadic FTD.
Violence exposure during childhood is common and associated with poor cognitive and academic functioning. However, little is known about how violence exposure influences cognitive processes that might contribute to these disparities, such as working memory, or their neural underpinnings, particularly for cognitive processes that occur in emotionally salient contexts. We address this gap in a sample of 54 participants aged 8 to 19 years (50% female), half with exposure to interpersonal violence. Participants completed a delayed match to sample task for emotional faces while undergoing functional magnetic resonance imaging scanning. Violence-exposed youth performed worse than controls on happy and neutral, but not angry, trials. In whole-brain analysis, violence-exposed youth had reduced activation in the left middle frontal gyrus and right intraparietal sulcus during encoding and the left superior temporal sulcus and temporal–parietal junction during retrieval compared to control youth. Reduced activation in the left middle frontal gyrus during encoding and the left superior temporal sulcus during retrieval mediated the association between violence exposure and task performance. Violence exposure influences the frontoparietal network that supports working memory as well as regions involved in facial processing during working memory for emotional stimuli. Reduced neural recruitment in these regions may explain atypical patterns of cognitive processing seen among violence-exposed youth, particularly within emotional contexts.
Post-traumatic stress disorder (PTSD) is associated with elevated risk for metabolic syndrome (MetS). However, the direction of this association is not yet established, as most prior studies employed cross-sectional designs. The primary goal of this study was to evaluate bidirectional associations between PTSD and MetS using a longitudinal design.
A total of 1355 male and female veterans of the conflicts in Iraq and Afghanistan underwent PTSD diagnostic assessments and their biometric profiles pertaining to MetS were extracted from the electronic medical record at two time points (spanning ~2.5 years, n = 971 at time 2).
The prevalence of MetS among veterans with PTSD was just under 40% at both time points and was significantly greater than that for veterans without PTSD; the prevalence of MetS among those with PTSD was also elevated relative to age-matched population estimates. Cross-lagged panel models revealed that PTSD severity predicted subsequent increases in MetS severity (β = 0.08, p = 0.002), after controlling for initial MetS severity, but MetS did not predict later PTSD symptoms. Logistic regression results suggested that for every 10 PTSD symptoms endorsed at time 1, the odds of a subsequent MetS diagnosis increased by 56%.
Results highlight the substantial cardiometabolic concerns of young veterans with PTSD and raise the possibility that PTSD may predispose individuals to accelerated aging, in part, manifested clinically as MetS. This demonstrates the need to identify those with PTSD at greatest risk for MetS and to develop interventions that improve both conditions.
We report on the Hubble Space Telescope (HST) observation of the polar, QS Tel, made during 1994 June. Orbital modulation is present in both the continuum and lines. A narrow dip is observed in the continuum folded light curve. The spectrum of the occulted source during this dip is broadly consistent in shape with the Rayleigh-Jeans tail of the EUV source.
Executive functioning is widely targeted when human cognition is assessed, but there is little consensus on how it should be operationalized and measured. Recognizing the difficulties associated with establishing standard operational definitions of executive functioning, the National Institute of Neurological Disorders and Stroke entered into a contract with the University of California-San Francisco to develop psychometrically robust executive measurement tools that would be accepted by the neurology clinical trials and clinical research communities. This effort, entitled Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER), resulted in a series of tasks targeting working memory, inhibition, set shifting, fluency, insight, planning, social cognition and behavior. We describe battery conceptualization and development, data collection, scale construction based on item response theory, and lay the foundation for studying the battery's utility and validity for specific assessment and research goals. (JINS, 2013, 19, 1–9)
Early-life stress, such as maltreatment, institutionalization, and exposure to violence, is associated with accelerated telomere shortening. Telomere shortening may thus represent a biomarker of early adversity. Previous studies have suggested that responsive parenting may protect children from the negative biological and behavioral consequences of early adversity. This study examined the role of parental responsiveness in buffering children from telomere shortening following experiences of early-life stress. We found that high-risk children had significantly shorter telomeres than low-risk children, controlling for household income, birth weight, gender, and minority status. Further, parental responsiveness moderated the association between risk and telomere length, with more responsive parenting associated with longer telomeres only among high-risk children. These findings suggest that responsive parenting may have protective benefits on telomere shortening for young children exposed to early-life stress. Therefore, this study has important implications for early parenting interventions.
Background: Cognitive training has been shown to improve memory in older adults; however, little is known about which individuals benefit from or respond best to training in the long term. Identification of responders’ characteristics would help providers match cognitive interventions to individuals to improve their effectiveness. Signal detection methods may prove more informative than more commonly used analytic methods. The goal of the current study is to identify baseline characteristics of long-term treatment responders and of those able to maintain their initial benefit from cognitive training.
Methods: Participants were 120 non-demented, community-dwelling older adults who had participated in a cognitive training intervention. Tested predictors included both demographic and neurocognitive variables. Primary outcome variables were performance on measures of memory at one-year follow-up.
Results: Results of the signal detection analysis indicated that different neurocognitive performances predicted long-term effects of memory training and maintenance of initial treatment response according to different types of to-be-remembered material. Higher baseline scores on tests of associative memory, delayed verbal memory, attention, episodic memory, and younger age were found predictive of long-term response one year later. Higher associative memory scores and lower initial gains at the end of treatment (week 14) predicted successful maintenance of training gains at week 52.
Conclusions: To derive long-term benefit from particular cognitive training programs, it appears necessary for older adults to have specific neurocognitive profiles. Further, inclusion of booster sessions to cognitive training programs may assist in maintenance of initial treatment gains.
Recent studies have claimed the existence of very massive stars (VMS) up to 300 M⊙ in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 M⊙, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processes.
On tests of design fluency, an examinee draws as many different designs as possible in a specified time limit while avoiding repetition. The neuroanatomical substrates and diagnostic group differences of design fluency repetition errors and total correct scores were examined in 110 individuals diagnosed with dementia, 53 with mild cognitive impairment (MCI), and 37 neurologically healthy controls. The errors correlated significantly with volumes in the right and left orbitofrontal cortex (OFC), the right and left superior frontal gyrus, the right inferior frontal gyrus, and the right striatum, but did not correlate with volumes in any parietal or temporal lobe regions. Regression analyses indicated that the lateral OFC may be particularly crucial for preventing these errors, even after excluding patients with behavioral variant frontotemporal dementia (bvFTD) from the analysis. Total correct correlated more diffusely with volumes in the right and left frontal and parietal cortex, the right temporal cortex, and the right striatum and thalamus. Patients diagnosed with bvFTD made significantly more repetition errors than patients diagnosed with MCI, Alzheimer's disease, semantic dementia, progressive supranuclear palsy, or corticobasal syndrome. In contrast, total correct design scores did not differentiate the dementia patients. These results highlight the frontal-anatomic specificity of design fluency repetitions. In addition, the results indicate that the propensity to make these errors supports the diagnosis of bvFTD. (JINS, 2012, 18, 1–11)
Molecular cluster calculations within the local density approximation have been performed in a study of the electronic structure of the C60 molecule - “Buckminsterfullerene” doped with K, B and N. Calculations for the KC60 molecule, with the K atom located at the centre of the cage as well as at different positions inside or outside the cage, show how the valence 4s electron is transferred to the LUMO state of the bare C60 molecule. Doping with a B or N atom located at the centre of the cage creates a molecule with a partly occupied level of 2p character in the HOMO and LUMO gap, similar to donor and acceptor levels in the band gap of traditionally doped semiconductors. Doping by substitution of one or two of the carbon atoms in the cage with X = B or N, as modelled with the C59 X1 or C58X2 clusters, gives a different structure with a splitting of the HOMO and LUMO levels in the pure C60 molecule and with the creation of acceptor and donor levels with the substitution of B and N, respectively.
The low energy part of the linear optical response spectrum and lowest order hyperpolarizability γ(3) of C60 are calculated by a sum over state approach using single particle wavefunctions and. energy levels determined from local density calculations. Lorentz local field factors, as well as a RPA correction are introducedto facilitate comparison with the dielectric function ε(ω) determined fromfilms of C60. γ( 2 ) for a centrosymmetric molecule such asC60 is zero and the lowest non-zero contribution to the polarizability is γ( 3 ). Reasonable agreement is found with linear optical response experiments if a RPA screening is used. However, SHG and THG experiments on C60 in solid or solution form, yields values closer to the unscreened results.
We demonstrate experimentally that linear polarization of porous Si photoluminescence depends significantly on the excitation geometry and describe this effect within the framework of a dielectric model in which porous Si is considered as an aggregate of slightly deformed, elongated and flattened, dielectric elliptical Si nanocrystals with preferred orientation in the  direction. The theoretical best-fit analysis of the experimental data allows us to get certain information concerning the shapes and orientation of the ellipsoids.
Propagation of a sharp temperature wave was observed during microwave heating of porous zinc oxide in nitrogen and argon atmospheres. This wave initiated from the center of the sample and traveled at an average velocity of 0.2 cm/min towards its surface. This temperature wave was attributed to an anomalous peak in the imaginary part of the complex permittivity possibly caused by desorption of chemisorbed oxygen from the surfaces of ZnO crystallites.
ZnO samples were sintered in an overmoded 2.45 GHz microwave applicator. In-situ differential temperature measurements were made to allow comparison of surface and core temperatures during heating. At intermediate temperatures, near 600°C, the sample core was measured to be more than 250°C hotter than the sample surface. As the core temperature approached 1100°C, however, the difference between the surface and core temperatures diminished. Post-sintering scanning electron microscopy (SEM) showed spatial variations in the residual porosity which were consistent with the measured temperature differential. For samples sintered to intermediate temperatures, where large temperature differences persisted, there were significant gradients in the residual porosity. For samples sintered to higher temperatures, there was little residual porosity and no observable porosity gradient. Local density versus temperature behavior was obtained by correlating porosity levels measured from the micrographs with temperature measurements made during sintering. These data demonstrate a significantly lower activation energy for microwave sintering than for conventional sintering.
Measurements of the complex dielectric constant of microwave sintered, porous ZnO at 2.45 GHz are presented. The dielectric properties as a function of porosity do not obey the standard Maxwell-Garnet dielectric mixing law with the ceramic material as the major phase, but instead behave as if the ceramic grains always remain in relatively poor electrical contact even at very high densities. Electromagnetic simulations, carried out for a variety of microstructure geometries, are performed to explore this observation. A model which treats the ceramic as an array of grains and pores, with the grains separated from each other by nonor slightly-percolating, fractal-geometry surfaces, provides a good description of the experimental results.