High-temperature synthesis, single-crystal X-ray and neutron powder diffraction, and materials properties of Sr3Ln10Si18Al12O18N36 (Ln = Ce, Pr, Nd)

The novel oxonitridoaluminosilicates (sialons) Sr3Ln10Si18Al12O18N36 (Ln = Ce, Pr, Nd) were obtained by the reaction of the respective lanthanide metals with Si(NH)2, SrCO3, and AlN using a radiofrequency furnace at temperatures between 1550–1650°C. The crystal structures of the isotypic sialons were determined by single-crystal X-ray investigations (Sr3Ce10Si18Al12O18N36: I3m, Z = 2, a = 1338.2(2) pm, R1 = 0.0333; Sr3Pr10Si18Al12O18N36: a = 1334.54(6) pm, R1 = 0.0296; Sr3Nd10Si18Al12O18N36: a = 1332.85(6) pm, R1 = 0.0271) and in the case of Sr3Pr10Si18Al12O18N36 with powder neutron diffraction as well. The three-dimensional sialon network is built up by SiON3, SiN4, and AlON3 tetrahedra. Besides the bridging O and N atoms of the sialon network there are isolated O2− which are tetrahedrally coordinated by Sr and Ln. The crystallographic differentiation of Si/Al and O/N seemed to be possible by a careful evaluation of the single-crystal X-ray diffraction data combined with lattice energy calculations using the MAPLE concept (Madelung Part of Lattice Energy). In the case of Sr3Pr10Si18Al12O18N36 the differentiation of O and N and the proposed ordering was completely confirmed by powder neutron diffraction

The Reservoir Age Effect Varies With the Mobilization of Pre-Aged Organic Carbon in a High-Altitude Central Asian Catchment

Lake sediments provide excellent archives to study past environmental and hydrological changes at high temporal resolution. However, their utility is often restricted by chronological uncertainties due to the “ reservoir age effect ” (RAE), a phenomenon that results in anomalously old radiocarbon ages of total organic carbon (TOC) samples that is mainly attributed to the contribution of pre-aged carbon from aquatic organisms. Although the RAE is a well-known problem especially in high altitude lakes, detailed studies analyzing the temporal variations in the contribution of terrestrial and aquatic organic carbon (OC) on the RAE are scarce. This is partially due to the complexity of isolating individual compounds for subsequent compound-speci fi c radiocarbon analysis (CSRA). We developed a rapid method for isolating individual short-chain (C 16 and C 18 ) and long-chain ( > C 24 ) saturated fatty acid methyl esters (FAMEs) by using high-pressure liquid chromatography (HPLC). Our method introduces only minor contaminations (0.50 ± 0.22 µg dead carbon on average) and requires only few injections ( ≤ 10), therefore offering clear advantages over traditional preparative gas chromatography (prep-GC). Here we show that radiocarbon values ( Δ 14C) of long-chain FAs, which originate from terrestrial higher plant waxes, re fl ect carbon from a substantially pre-aged OC reservoir, whereas the Δ 14C of short-chain FAs that originate from aquatic sources were generally less pre-aged. 14 C ages obtained from the long-chain FAs are in closer agreement with 14 C ages of the corresponding bulk TOC fraction, indicating a high control of pre-aged terrestrial OC input from the catchment on TOC-derived 14 C ages. Variations in the age offset between terrestrial and aquatic biomarkers are related to changes in bulk sediment log(Ti/K) that re fl ect variations in detrital input from the catchment. Our results indicate that the chronological offset between terrestrial and aquatic OC in this high-altitude catchment is mainly driven by temporal variations in the mobilization of pre-aged OC from the catchment. In conclusion, to obtain accurate and process-speci fi c lake sediment chronologies, attention must be given to the temporal dynamics of the RAE. Variations in the apparent ages of aquatic and terrestrial contributions to the sediment and their mass balance can substantially alter the reservoir age effect

The Neuroprotective Disease-Modifying Potential of Psychotropics in Parkinson's Disease

Neuroprotective treatments in Parkinson's disease (PD) have remained elusive. Psychotropics are commonly prescribed in PD without regard to their pathobiological effects. The authors investigated the effects of psychotropics on pathobiological proteins, proteasomal activity, mitochondrial functions, apoptosis, neuroinflammation, trophic factors, stem cells, and neurogenesis. Only findings replicated in at least 2 studies were considered for these actions. Additionally, PD-related gene transcription, animal model, and human neuroprotective clinical trial data were reviewed. Results indicate that, from a PD pathobiology perspective, the safest drugs (i.e., drugs least likely to promote cellular neurodegenerative mechanisms balanced against their likelihood of promoting neuroprotective mechanisms) include pramipexole, valproate, lithium, desipramine, escitalopram, and dextromethorphan. Fluoxetine favorably affects transcription of multiple genes (e.g., MAPT, GBA, CCDC62, HIP1R), although it and desipramine reduced MPTP mouse survival. Haloperidol is best avoided. The most promising neuroprotective investigative priorities will involve disease-modifying trials of the safest agents alone or in combination to capture salutary effects on H3 histone deacetylase, gene transcription, glycogen synthase kinase-3, α-synuclein, reactive oxygen species (ROS), reactive nitrogen species (RNS), apoptosis, inflammation, and trophic factors including GDNF and BDNF

The effect of force-field parameters on properties of liquids:Parametrization of a simple three-site model for methanol

A simple rigid three-site model for methanol compatible with the simple point charge (SPC) water and the GROMOS96 force field is parametrized and tested. The influence of different force-field parameters, such as the methanol geometry and the charge distribution on several properties calculated by molecular dynamics is investigated. In particular an attempt was made to obtain good agreement with experimental data for the static dielectric constant and the mixing enthalpy with water. The model is compared to other methanol models from the literature in terms of the ability to reproduce a range of experimental properties.<br/

The Draw-A-Clock Contest: A Strategy for Improving Cognitive Status Assessment by Trainees

Background: Historically, psychiatrists have been less inclined than neurologists to utilize pencil and paper tasks during bedside cognitive assessments. Objective: The Draw-AClock Contest was established in 1986 at the University of Massachusetts to promote use of cognitive assessment tasks by psychiatry residents. Methods: Used in neuropsychological assessments since the 1930’s, clock tasks have been popular screening tools for executive function, praxis, visuospatial and constructive ability, often as part of dementia screening. Given its broad utility as a screening tool and the ease and speed of its administration, the Draw-A-Clock task (with hands set to 11:10 and no circle provided) was selected for use by UMass psychiatry residents, with further bedside assessment encouraged to explore any detected deficits. To encourage participation and foster clinical inquiry, residents are asked to submit clinically interesting de-identified patient clocks. For 21 years, clock contest entries have been collected each spring, with basic demographic, diagnostic, and process notes. Resident names are encoded, and entries are judged by a neuropsychiatrist (SB) and a neuropsychologist (EK). A “clock trophy” and detailed analysis of the submission is presented to the winner at the annual graduation banquet. Results: As a result of this contest, mental status examinations by trainees have become more comprehensive and an atmosphere of neuropsychiatric inquiry has been maintained. Faculty members have also incorporated this task into their mental status assessments, thus establishing a culture of cognitive inquiry and an academic tradition. Examples of winning clocks and common findings will be presented. Published abstract: Sullivan J, Benjamin S, Case Report: CADASIL with Cysteine-Sparing Notch-3 Mutation, American Neuropsychiatric Association, abstract, Journal of Neuropsychiatry and Clinical Neuroscience 21(2):221, 2009. DOI 10.1176/appi.neuropsych.21.2.221

Variable strength of forest stand attributes and weather conditions on the questing activity of Ixodes ricinus ticks over years in managed forests

Given the ever-increasing human impact through land use and climate change on the environment, we crucially need to achieve a better understanding of those factors that influence the questing activity of ixodid ticks, a major disease-transmitting vector in temperate forests. We investigated variation in the relative questing nymph densities of Ixodes ricinus in differently managed forest types for three years (2008–2010) in SW Germany by drag sampling. We used a hierarchical Bayesian modeling approach to examine the relative effects of habitat and weather and to consider possible nested structures of habitat and climate forces. The questing activity of nymphs was considerably larger in young forest successional stages of thicket compared with pole wood and timber stages. Questing nymph density increased markedly with milder winter temperatures. Generally, the relative strength of the various environmental forces on questing nymph density differed across years. In particular, winter temperature had a negative effect on tick activity across sites in 2008 in contrast to the overall effect of temperature across years. Our results suggest that forest management practices have important impacts on questing nymph density. Variable weather conditions, however, might override the effects of forest management practices on the fluctuations and dynamics of tick populations and activity over years, in particular, the preceding winter temperatures. Therefore, robust predictions and the detection of possible interactions and nested structures of habitat and climate forces can only be quantified through the collection of long-term data. Such data are particularly important with regard to future scenarios of forest management and climate warming