Computational Study of Copper(II) Complexation and Hydrolysis in Aqueous Solutions Using Mixed Cluster/Continuum Models

We use density functional theory (B3LYP) and the COSMO continuum solvent model to characterize the structure and stability of the hydrated Cu(II) complexes [Cu(MeNH_2)(H_2O)_(n−1)]^(2+) and [Cu(OH)_x(H_2O)_(n−x)]^(2−x) (x = 1−3) as a function of metal coordination number (4−6) and cluster size (n = 4−8, 18). The small clusters with n = 4−8 are found to be the most stable in the nearly square-planar four-coordinate configuration, except for [Cu(OH)_3(H_2O)]^−, which is three-coordinate. In the presence of the two full hydration shells (n = 18), however, the five-coordinate square-pyramidal geometry is the most favorable for Cu(MeNH_2)^(2+) (5, 6) and Cu(OH)^+ (5, 4, 6), and the four-coordinate geometry is the most stable for Cu(OH)_2 (4, 5) and Cu(OH)_3^− (4). (Other possible coordination numbers for these complexes in the aqueous phase are shown in parentheses.) A small energetic difference between these structures (0.23−2.65 kcal/mol) suggests that complexes with different coordination numbers may coexist in solution. Using two full hydration shells around the Cu^(2+) ion (18 ligands) gives Gibbs free energies of aqueous reactions that are in excellent agreement with experiment. The mean unsigned error is 0.7 kcal/mol for the three consecutive hydrolysis steps of Cu^(2+) and the complexation of Cu^(2+) with methylamine. Conversely, calculations for the complexes with only one coordination shell (four equatorial ligands) lead to a mean unsigned error that is >6.0 kcal/mol. Thus, the explicit treatment of the first and the second shells is critical for the accurate prediction of structural and thermodynamic properties of Cu(II) species in aqueous solution

Design of Multi-Antenna System for UMTS Clamshell Mobile Phones with Ground Plane Effects Considerations

In this paper, the influence of the ground plane dimensions on the port-to-port isolation of two closely-spaced Universal Mobile Telecommunications System (UMTS) Planar Inverted-F Antennas (PIFAs) with and without neutralization line is first presented. Parametric studies show the existence of an optimal size of the ground plane allowing optimizing the isolation and the efficiency of the considered antenna-system. The results obtained with this study are used in the second part to develop an efficient neutralized multi-antenna system for clamshell-type mobile phones. The obtained results, in terms of isolation, matching and diversity for the two possible configurations of the clamshell system in use namely the open and the closed states, show that good performance are obtained in the open state and preserved in the closed state. Prototypes of these two configurations are realized and measurement results are in good agreement with the simulations

Variations spatio-temporelles du zooplancton d'un estuaire hyperhalin : la Casamance

La Casamance est un fleuve côtier du sud du Sénégal (Afrique de l'Ouest) pourvu d'une zone estuarienne relativement vaste. Le déficit pluviométrique de ces deux dernières décennies, combiné à une forte évaporation a contribué à une augmentation anormale de la salinité laquelle atteint 172 °/°° en amont, en fin de saison sèche 1986. La répartition spatio-temporelle du zooplancton semble dépendre de la température et de la salinité. Le zooplancton est abondant et diversifié (cinquante-six espèces adultes dont 55 % de copépodes et 13 types de larves; effectif pouvant atteindre 16500 individus/m3; indice de Shannon d'environ 3) tant que la salinité reste inférieure à 70 °/°°. En aval d'Adéane (93 km de l'embouchure), les salinités dépassent rarement cette valeur et les variations saisonnières du zooplancton suivent celles de la température (maximums en saison chaude de mars à novembre, et minimums en saison froide). En amont, la salinité, par l'amplitude de ses variations, devient le facteur prépondérant pour expliquer les variations spatio-temporelles du zooplancton,qui devient moint abondant et moins diversifié (6 à 18 espèces suivant les stations et les époques). (Résumé d'auteur

Dynamics of plasma blobs in a shear flow

The global dynamic of plasma blobs in a shear flow is investigated in a simple magnetized torus using the spatial Fourier harmonics (k-space) framework. Direct experimental evidence of a linear drift in k space of the density fluctuation energy synchronized with blob events is presented. During this drift, an increase of the fluctuation energy and a production of the kinetic energy associated with blobs are observed. The energy source of the blob is analyzed using an advection-dissipation-type equation that includes blob-flow exchange energy, linear drift in k space, nonlinear processes, and viscous dissipations. We show that blobs tap their energy from the dominant E B vertical background flow during the linear drift stage. The exchange of energy is unidirectional as there is no evidence that blobs return energy to the flow

PAMAM Dendrimers Undergo pH Responsive Conformational Changes without Swelling

Atomistic molecular dynamics (MD) simulations of a G4-NH2 PAMAM dendrimer were carried out in aqueous solution using explicit water molecules and counterions (with the Dreiding III force field optimized using quantum mechanics). Our simulations predict that the radius of gyration (R_g) of the dendrimer changes little with pH from 21.1 Å at pH 10 (uncharged PAMAM) to 22.1 Å at pH 5 (charged with 126 protons), which agrees quantitatively with recent small angle neutron scattering (SANS) experiments (from 21.4 Å at pH 10 to 21.5 Å at pH 5). Even so we predict a dramatic change in the conformation. The ion pairing in the low pH form leads to a locally compact dense shell with an internal surface area only 37% of the high pH form with a dense core. This transformation from “dense core” at high pH to “dense shell” at low pH could facilitate the encapsulation and release of guest molecules (e.g., drugs) using pH as the trigger, making dendrimers a unique drug delivery vehicle

Facteurs de risque, épidémiologie et prise en charge de la grossesse extra-utérine rompue (GEUR) au service de gynécologie et d’obstétrique de l’hôpital national Ignace Deen du CHU de Conakry en 2022

Introduction : urgence gynécologique fréquente, découverte fortuite aux urgences médicales et ou chirurgicales dans un tableau d’anémie. L’objectif de cette étude était d’étudier les facteurs de risque, épidémiologie, et prise en charge de la grossesse extra-utérine rompue au service de gynécologie et d’obstétrique de l’hôpital national Ignace Deen du CHU de Conakry en 2022. Méthodes : il s’agissait d’une étude descriptive transversale à recrutement rétrospectif. Elle a été menée au service de gynécologie et d’obstétrique de l’hôpital national Ignace Deen du CHU de Conakry du 1er janvier  2019 au 31 Décembre 2022 soit une période de trois ans. Ont été étudiées les variables se rapportant aux facteurs de risque, épidémiologie, et la prise en charge de la GEUR dans notre contexte de travail. Nous avons utilisé le logiciel Excel pour l’analyse des données.    Résultats : fréquence de la GEUR dans notre étude était 1,26 % sur l’ensemble des interventions gynécologiques, les tranches d’âge les plus représentées étaient celles de 20-24 ans et 30-34 ans de 32,69%, plus de la moitié était célibataire 69,23%, sans profession, non scolarisé respectivement 64,23% et 42,31%, primipares dans 49,04%.  Parmi les facteurs de risque (FDR) retrouvés dans notre série, figuraient antécédent de :  l’infection génitale 46,15%, fausses couches spontanées 10,58%, la contraception par microprogestatif 16,34%. La prise en charge a été exclusivement chirurgicale (100%), associée à la transfusion sanguine comme moyen de réanimation dans 95,16%. Conclusion : la grossesse extra-utérine rompue est une urgence médicochirurgicale fréquente, le diagnostic précoce traine les pas dans les pays à faibles ressources.    Introduction : a frequent gynecological emergency, discovered incidentally in medical and/or surgical emergencies in the setting of anemia. The aim of this study was to investigate the risk factors and management of ectopic pregnancy in the gynecology and obstetrics department of the Ignace Deen National Hospital of Conakry University Hospital in 2022. Methods : This was a descriptive study with retrospective recruitment. It was conducted at the gynecology and obstetrics department of the CHU Ignace Deen national hospital in Conakry from January 1, 2019 to December 31, 2022, a three-year period. Variables relating to risk factors, epidemiology and management of GEUR in our working context were studied. We used Excel software for data analysis. Results : The frequency of GEUR in our study was 1.26% of all gynaecological procedures, the most represented age groups were 20-24 and 30-34 years with 32.69%, more than half were single 69.23%, without profession, not in school respectively 64.23% and 42.31%, primiparous in 49.04%.  Among the risk factors found in our series were a history of : genital infection 46,15%, spontaneous miscarriage 10.58%, microprogestogen contraception 16.34%. Management was exclusively surgical (100%), associated with blood transfusion as a means of resuscitation in 95.16% Conclusion : Ruptured ectopic pregnancy is a frequent medico-surgical emergency, early diagnosis is lagging behind in low-resource countries