Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups

La Prévalence des Pathologies Thyroïdiennes chez le Sujet Âgé au Service de Médecine Interne de l’Hôpital National Donka

Introduction : Le vieillissement est associé à des modifications complexes de la fonction thyroïdienne qui interviennent à plusieurs niveaux de régulation. La sécrétion des hormones thyroïdiennes est en général dans les limites inférieures des valeurs usuelles. Méthodes : Il s’agissait d’une étude rétrospective à visée descriptive et analytique menée du 1er janvier 2013 au 31 décembre 2022 (soit 10 ans). L’étude était réalisée au service de médecine interne de l’hôpital national Donka (Guinée). Elle a porté sur les sujets âgés de 60 ans et plus suivis pour une pathologie thyroïdienne. Résultats : Durand la période d’étude nous avons colligé 88 cas de dysthyroïdies soit une prévalence de 17,95 %. Il y avait une prédominance féminine (56 cas) avec un sex ratio H/F de 0,57. L’âge moyen était de 64,5 ans (extrêmes de 60 et 85 ans). Les circonstances de diagnostic de la maladie thyroïdienne étaient principalement un goitre (59,1%), une exophtalmie (9,1%), une compression cervicale (25%), une cardiothyréose (5,7 %). Les principales manifestations de la thyrotoxicose étaient l’amaigrissement (17%), les palpitations (29,5%) et la fatigabilité (34,1%). Les signes d’hypothyroïdie prédominants étaient la constipation (17%) et le syndrome myxœdémateux (3,4%). L’hyperthyroïdie a été rencontrée chez 13,64% des patients, contre 29,54% de cas d’hypothyroïdie. L’échographie cervicale thyroïdienne avait retrouvé 36 cas de goitre diffus (40,9%), 18 cas de goitre multinodulaire (20,45%), 17 cas de nodule unique (19,31%). Les principales étiologies étaient la maladie de Basedow (11,4%), le goitre multinodulaire (46,6%), la thyroïdite de Hashimoto (17%), un goitre simple (5,7%). La thyroïdectomie avait concerné 33 patients (37,5%). Deux cas de décès étaient enregistrés en rapport avec une cardiothyréose. Conclusion : Les dysthyroïdies sont fréquentes chez le sujet âgé au CHU de Conakry et un dosage hormonal au moindre doute afin d’instaurer le traitement adéquat à temps serait requis afin de prévenir les complications.   Introduction: The aging is associated with complex changes in thyroid function that occur at several levels of regulation. Thyroid hormone secretion is generally within the lower limits of usual values. Methods: This was a retrospective study with descriptive and analytical aims carried out from January 1, 2013 to December 31, 2022 (i.e. 10 years). The study was carried out in the internal medicine department of the Donka national hospital (Guinea). It focused on subjects aged 60 and over followed for thyroid pathology. Results: During the study period we collected 88 cases of dysthyroidism, representing a prevalence of 17.95%. There was a female predominance (56 cases) with a M/F sex ratio of 0.57. The average age was 64.5 years (range 60 and 85 years). The circumstances of diagnosis of thyroid disease were mainly goiter (59.1%), exophthalmos (9.1%), cervical compression (25%), cardiothyreosis (5.7%). The main manifestations of thyrotoxicosis were weight loss (17%), palpitations (29.5%), and fatigability (34.1%). The predominant signs of hypothyroidism were constipation (17%) and myxedematous syndrome (3.4%). Hyperthyroidism was encountered in 13.64% of patients, compared to 29.54% cases of hypothyroidism. Cervical thyroid ultrasound found 36 cases of diffuse goiter (40.9%), 18 cases of multinodular goiter (20.45%), 17 cases of single nodule (19.31%). The main etiologies were Graves' disease (11.4%), multinodular goiter (46.6%), Hashimoto's thyroiditis (17%), simple goiter (5.7%). Thyroidectomy involved 33 patients (37.5%). Two cases of death were recorded in connection with cardiothyreosis. Conclusion: Dysthyroidism is common in the elderly at the Conakry University Hospital and a hormonal dosage if there is the slightest doubt in order to initiate the appropriate treatment in time would be required in order to prevent complications

La Prévalence des Pathologies Thyroïdiennes chez le Sujet Âgé au Service de Médecine Interne de l’Hôpital National Donka

Introduction : Le vieillissement est associé à des modifications complexes de la fonction thyroïdienne qui interviennent à plusieurs niveaux de régulation. La sécrétion des hormones thyroïdiennes est en général dans les limites inférieures des valeurs usuelles. Méthodes : Il s’agissait d’une étude rétrospective à visée descriptive et analytique menée du 1er janvier 2013 au 31 décembre 2022 (soit 10 ans). L’étude était réalisée au service de médecine interne de l’hôpital national Donka (Guinée). Elle a porté sur les sujets âgés de 60 ans et plus suivis pour une pathologie thyroïdienne. Résultats : Durand la période d’étude nous avons colligé 88 cas de dysthyroïdies soit une prévalence de 17,95 %. Il y avait une prédominance féminine (56 cas) avec un sex ratio H/F de 0,57. L’âge moyen était de 64,5 ans (extrêmes de 60 et 85 ans). Les circonstances de diagnostic de la maladie thyroïdienne étaient principalement un goitre (59,1%), une exophtalmie (9,1%), une compression cervicale (25%), une cardiothyréose (5,7 %). Les principales manifestations de la thyrotoxicose étaient l’amaigrissement (17%), les palpitations (29,5%) et la fatigabilité (34,1%). Les signes d’hypothyroïdie prédominants étaient la constipation (17%) et le syndrome myxœdémateux (3,4%). L’hyperthyroïdie a été rencontrée chez 13,64% des patients, contre 29,54% de cas d’hypothyroïdie. L’échographie cervicale thyroïdienne avait retrouvé 36 cas de goitre diffus (40,9%), 18 cas de goitre multinodulaire (20,45%), 17 cas de nodule unique (19,31%). Les principales étiologies étaient la maladie de Basedow (11,4%), le goitre multinodulaire (46,6%), la thyroïdite de Hashimoto (17%), un goitre simple (5,7%). La thyroïdectomie avait concerné 33 patients (37,5%). Deux cas de décès étaient enregistrés en rapport avec une cardiothyréose. Conclusion : Les dysthyroïdies sont fréquentes chez le sujet âgé au CHU de Conakry et un dosage hormonal au moindre doute afin d’instaurer le traitement adéquat à temps serait requis afin de prévenir les complications.   Introduction: The aging is associated with complex changes in thyroid function that occur at several levels of regulation. Thyroid hormone secretion is generally within the lower limits of usual values. Methods: This was a retrospective study with descriptive and analytical aims carried out from January 1, 2013 to December 31, 2022 (i.e. 10 years). The study was carried out in the internal medicine department of the Donka national hospital (Guinea). It focused on subjects aged 60 and over followed for thyroid pathology. Results: During the study period we collected 88 cases of dysthyroidism, representing a prevalence of 17.95%. There was a female predominance (56 cases) with a M/F sex ratio of 0.57. The average age was 64.5 years (range 60 and 85 years). The circumstances of diagnosis of thyroid disease were mainly goiter (59.1%), exophthalmos (9.1%), cervical compression (25%), cardiothyreosis (5.7%). The main manifestations of thyrotoxicosis were weight loss (17%), palpitations (29.5%), and fatigability (34.1%). The predominant signs of hypothyroidism were constipation (17%) and myxedematous syndrome (3.4%). Hyperthyroidism was encountered in 13.64% of patients, compared to 29.54% cases of hypothyroidism. Cervical thyroid ultrasound found 36 cases of diffuse goiter (40.9%), 18 cases of multinodular goiter (20.45%), 17 cases of single nodule (19.31%). The main etiologies were Graves' disease (11.4%), multinodular goiter (46.6%), Hashimoto's thyroiditis (17%), simple goiter (5.7%). Thyroidectomy involved 33 patients (37.5%). Two cases of death were recorded in connection with cardiothyreosis. Conclusion: Dysthyroidism is common in the elderly at the Conakry University Hospital and a hormonal dosage if there is the slightest doubt in order to initiate the appropriate treatment in time would be required in order to prevent complications

On Passion and Sports Fans:A Look at Football

The purpose of the present research was to test the applicability of the Dualistic Model of Passion (Vallerand et al., 2003) to being a sport (football) fan. The model posits that passion is a strong inclination toward an activity that individuals like (or even love), that they value, and in which they invest time and energy. Furthermore, two types of passion are proposed: harmonious and obsessive passion. While obsessive passion entails an uncontrollable urge to engage in the passionate activity, harmonious passion entails a sense of volition while engaging in the activity. Finally, the model posits that harmonious passion leads to more adaptive outcomes than obsessive passion. Three studies provided support for this dualistic conceptualization of passion. Study 1 showed that harmonious passion was positively associated with adaptive behaviours (e.g., celebrate the team’s victory), while obsessive passion was rather positively associated with maladaptive behaviours (e.g., to risk losing one’s employment to go to the team’s game). Study 2 used a short Passion Scale and showed that harmonious passion was positively related to the positive affective life of fans during the 2006 FIFA World Cup, psychological health (self-esteem and life satisfaction), and public displays of adaptive behaviours (e.g., celebrating one’s team victory in the streets), while obsessive passion was predictive of maladaptive affective life (e.g., hating opposing team’s fans) and behaviours (e.g., mocking the opposing team’s fans). Finally, Study 3 examined the role of obsessive passion as a predictor of partner’s conflict that in turn undermined partner’s relationship satisfaction. Overall, the present results provided support for the Dualistic Model of Passion. The conceptual and applied implications of the findings are discussed

Unusual cage rearrangements in 10-vertex nido-5,6-dicarbaborane derivatives : An interplay between theory and experiment

The reaction between selected X-nido-5,6-C2B8H11 compounds (where X = Cl, Br, I) and "Proton Sponge" [PS; 1,8-bis(dimethylamino)naphthalene], followed by acidification, results in extensive rearrangement of all cage vertices. Specifically, deprotonation of 7-X-5,6-C2B8H11 compounds with one equivalent of PS in hexane or CH2Cl2 at ambient temperature led to a 7 → 10 halogen rearrangement, forming a series of PSH+[10-X-5,6-C2B8H10]- salts. Reprotonation using concentrated H2SO4 in CH2Cl2 generates a series of neutral carbaboranes 10-X-5,6-C2B8H11, with the overall 7 → 10 conversion being 75%, 95%, and 100% for X = Cl, Br, and I, respectively. Under similar conditions, 4-Cl-5,6-C2B8H11 gave ∼66% conversion to 3- Cl-5,6-C2B8H11. Since these rearrangements could not be rationalized using the Bvertex swing mechanism, new cage rearrangement mechanisms, which are substantiated using DFT calculations, have been proposed. Experimental 11B NMR chemical shifts are well reproduced by the computations; as expected δ(11B) for B(10) atoms in derivatives with X = Br and I are heavily affected by spin-orbit coupling

Direct Experimental Observation of in situ Dehydrogenation of an Amine-Borane System Using Gas Electron Diffraction

In situ dehydrogenation of azetidine-BH3, which is a candidate for hydrogen storage, was observed with the parent and dehydrogenated analogue subjected to rigorous structural and thermochemical investigations. The structural analyses utilized gas electron diffraction supported by high-level quantum calculations, while the pathway for the unimolecular hydrogen release reaction in the absence and presence of BH3 as a bifunctional catalyst was predicted at the CBS-QB3 level. The catalyzed dehydrogenation pathway has a barrier lower than the predicted B-N bond dissociation energy, hence favoring the dehydrogenation process over the dissociation of the complex. The predicted enthalpy of dehydrogenation at the CCSD(T)/CBS level indicates that mild reaction conditions would be required for hydrogen release and that the compound is closer to thermoneutral than linear amine boranes. The entropy and free energy change for the dehydrogenation process show that the reaction is exergonic, energetically feasible, and will proceed spontaneously toward hydrogen release, all of which are important factors for hydrogen storage

A compact electron gun for time-resolved electron diffraction

A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern

Structures of tetrasilylmethane derivatives C(SiXMe2)4 (X = H, F, Cl, Br) in the gas phase and their dynamic structures in solution.

The structures of the molecules C(SiXMe2)4 (X = H, F, Cl, Br) have been determined by gas electron diffraction (GED). Ab initio calculations revealed nine potential minima for each species, with significant ranges of energies. For the H, F, Cl, and Br derivatives nine, seven, two, and two conformers were modelled, respectively, as they were quantum-chemically predicted to be present in measurable quantities. Variable-temperature 1H and 29Si solution-phase NMR studies and, where applicable, 13C NMR, 1H/29Si NMR shift-correlation, and 1H NMR saturation-transfer experiments are reported for C(SiXMe2)4 (X = H, Cl, Br, and also I). At low temperature in solution two conformers (one C1-symmetric and one C2-symmetric) are observed for each of C(SiXMe2)4 (X = Cl, Br, I), in agreement with the isolated molecule ab initiocalculations carried out as part of this work for X = Cl, Br. C(SiHMe2)4 is present as a single C1-symmetric conformer in solution at the temperatures at which the NMR experiments were performed