517 research outputs found

    Modeling molecular crystals formed by spin-active metal complexes by atom-atom potentials

    Full text link
    We apply the atom-atom potentials to molecular crystals of iron (II) complexes with bulky organic ligands. The crystals under study are formed by low-spin or high-spin molecules of Fe(phen)2_{2}(NCS)2_{2} (phen = 1,10-phenanthroline), Fe(btz)2_{2}(NCS)2_{2} (btz = 5,5′^{\prime },6,6′^{\prime}-tetrahydro-4\textit{H},4′^{\prime}\textit{H}-2,2′^{\prime }-bi-1,3-thiazine), and Fe(bpz)2_{2}(bipy) (bpz = dihydrobis(1-pyrazolil)borate, and bipy = 2,2′^{\prime}-bipyridine). All molecular geometries are taken from the X-ray experimental data and assumed to be frozen. The unit cell dimensions and angles, positions of the centers of masses of molecules, and the orientations of molecules corresponding to the minimum energy at 1 atm and 1 GPa are calculated. The optimized crystal structures are in a good agreement with the experimental data. Sources of the residual discrepancies between the calculated and experimental structures are discussed. The intermolecular contributions to the enthalpy of the spin transitions are found to be comparable with its total experimental values. It demonstrates that the method of atom-atom potentials is very useful for modeling organometalic crystals undergoing the spin transitions

    Deuteron photo-disintegration with polarised photons in the energy range 30 - 50 MeV

    Full text link
    The reaction d(\vec\gamma,np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30 - 50 MeV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle \vartheta_n = 22, 55.5, 90, 125 and 157 degrees in the center of mass system.Our results do not support the existence of such resonances.Comment: 16 pages, Latex, 22 figures, 1 table. Nucl. Phys. A to appea

    Association of metabolic syndrome and change in Unified Parkinson\u27s Disease Rating Scale scores.

    Get PDF
    OBJECTIVE: To explore the association between metabolic syndrome and the Unified Parkinson\u27s Disease Rating Scale (UPDRS) scores and, secondarily, the Symbol Digit Modalities Test (SDMT). METHODS: This is a secondary analysis of data from 1,022 of 1,741 participants of the National Institute of Neurological Disorders and Stroke Exploratory Clinical Trials in Parkinson Disease Long-Term Study 1, a randomized, placebo-controlled trial of creatine. Participants were categorized as having or not having metabolic syndrome on the basis of modified criteria from the National Cholesterol Education Program Adult Treatment Panel III. Those who had the same metabolic syndrome status at consecutive annual visits were included. The change in UPDRS and SDMT scores from randomization to 3 years was compared in participants with and without metabolic syndrome. RESULTS: Participants with metabolic syndrome (n = 396) compared to those without (n = 626) were older (mean [SD] 63.9 [8.1] vs 59.9 [9.4] years; p \u3c 0.0001), were more likely to be male (75.3% vs 57.0%; p \u3c 0.0001), and had a higher mean uric acid level (men 5.7 [1.3] vs 5.3 [1.1] mg/dL, women 4.9 [1.3] vs 3.9 [0.9] mg/dL, p \u3c 0.0001). Participants with metabolic syndrome experienced an additional 0.6- (0.2) unit annual increase in total UPDRS (p = 0.02) and 0.5- (0.2) unit increase in motor UPDRS (p = 0.01) scores compared with participants without metabolic syndrome. There was no difference in the change in SDMT scores. CONCLUSIONS: Persons with Parkinson disease meeting modified criteria for metabolic syndrome experienced a greater increase in total UPDRS scores over time, mainly as a result of increases in motor scores, compared to those who did not. Further studies are needed to confirm this finding. CLINICALTRIALSGOV IDENTIFIER: NCT00449865

    Enhanced Recovery After Surgery (ERAS) protocol in bariatric and metabolic surgery (BMS)-analysis of practices in nutritional aspects from five continents

    Get PDF
    This study aims to understand the prevalent practices on the nutritional aspects of the enhanced recovery after surgery (ERAS) protocol based on the knowledge and practice of surgeons, nutritionists, and anesthesiologists who work in the bariatric and metabolic surgery (BMS) units worldwide. This cross-sectional study enrolled BMS unit professionals from five continents-Africa, America, Asia, Europe, and Oceania. An electronic questionnaire developed by the researchers was provided to evaluate practices about the three nutritional aspects of ERAS protocol in BMS (Thorel et al. 2016): preoperative fasting, carbohydrate loading, and early postoperative nutrition. Only surgeons, nutritionists, and anesthesiologists were invited to participate. One hundred twenty-five professionals answered the questionnaires: 50.4% from America and 39.2% from Europe. The profile of participating professionals was bariatric surgeons 70.2%, nutritionists 26.4%, and anesthesiologists 3.3%. Approximately 47.9% of professionals work in private services, for about 11 to 20 years (48.7%). In all continents, a large majority were aware of the protocol. Professionals from the African continent reported having implemented the ERAS bariatric protocol 4.0 ± 0 years ago. It is worth mentioning that professionals from the five continents implemented the ERAS protocol based on the published literature (p = 0.012). About preoperative fasting abbreviation protocol, a significant difference was found between continents and consequently between services (p = 0.000). There is no uniformity in the conduct of shortening of fasting in the preoperative period and the immediate postoperative period. Early postoperative (PO) period protein supplementation is not performed in a standard fashion in all units globally. ERAS principles and practices are partial and insufficiently implemented on the five continents despite the prevalent knowledge of professionals based on evidence. Moreover, there is no uniformity in fasting, immediate postoperative diet, and early protein supplementation practices globally.info:eu-repo/semantics/publishedVersio

    Collective effects in spin-crossover chains with exchange interaction

    Full text link
    The collective properties of spin-crossover chains are studied. Spin-crossover compounds contain ions with a low-spin ground state and low lying high-spin excited states and are of interest for molecular memory applications. Some of them naturally form one-dimensional chains. Elastic interaction and Ising exchange interaction are taken into account. The transfer-matrix approach is used to calculate the partition function, the fraction of ions in the high-spin state, the magnetization, susceptibility, etc., exactly. The high-spin-low-spin degree of freedom leads to collective effects not present in simple spin chains. The ground-state phase diagram is mapped out and compared to the case with Heisenberg exchange interaction. The various phases give rise to characteristic behavior at nonzero temperatures, including sharp crossovers between low- and high-temperature regimes. A Curie-Weiss law for the susceptibility is derived and the paramagnetic Curie temperature is calculated. Possible experiments to determine the exchange coupling are discussed.Comment: 9 pages, 13 color figures, published versio

    Revisiting protein aggregation as pathogenic in sporadic Parkinson and Alzheimer diseases.

    Get PDF
    The gold standard for a definitive diagnosis of Parkinson disease (PD) is the pathologic finding of aggregated α-synuclein into Lewy bodies and for Alzheimer disease (AD) aggregated amyloid into plaques and hyperphosphorylated tau into tangles. Implicit in this clinicopathologic-based nosology is the assumption that pathologic protein aggregation at autopsy reflects pathogenesis at disease onset. While these aggregates may in exceptional cases be on a causal pathway in humans (e.g., aggregated α-synuclein in SNCA gene multiplication or aggregated β-amyloid in APP mutations), their near universality at postmortem in sporadic PD and AD suggests they may alternatively represent common outcomes from upstream mechanisms or compensatory responses to cellular stress in order to delay cell death. These 3 conceptual frameworks of protein aggregation (pathogenic, epiphenomenon, protective) are difficult to resolve because of the inability to probe brain tissue in real time. Whereas animal models, in which neither PD nor AD occur in natural states, consistently support a pathogenic role of protein aggregation, indirect evidence from human studies does not. We hypothesize that (1) current biomarkers of protein aggregates may be relevant to common pathology but not to subgroup pathogenesis and (2) disease-modifying treatments targeting oligomers or fibrils might be futile or deleterious because these proteins are epiphenomena or protective in the human brain under molecular stress. Future precision medicine efforts for molecular targeting of neurodegenerative diseases may require analyses not anchored on current clinicopathologic criteria but instead on biological signals generated from large deeply phenotyped aging populations or from smaller but well-defined genetic-molecular cohorts

    DĂ–NER KEBAB RETAILED ON THE LUCCA AREA: RESULTS OF SURVEILLANCE ACTIVITY

    Get PDF
    In this study the results of surveillance activity on döner kebab retailed on the Lucca area are reported. Ten kebab shops were inspected by health officers and food samples, including raw kebab, cooked kebab and sandwiches with kebab, were submitted for microbiological examinations. During surveillance activity some hygiene problems and difficult application of control plan were found. The microbiological analyses showed that döner kebab retailed in Lucca area had acceptable hygienic quality, but further inspections are necessary to improve the hygienic conditions of kebab shops
    • …
    corecore