Methyl group dynamics in a confined glass

We present a neutron scattering investigation on methyl group dynamics in glassy toluene confined in mesoporous silicates of different pore sizes. The experimental results have been analysed in terms of a barrier distribution model, such a distribution following from the structural disorder in the glassy state. Confinement results in a strong decreasing of the average rotational barrier in comparison to the bulk state. We have roughly separated the distribution for the confined state in a bulk-like and a surface-like contribution, corresponding to rotors at a distance from the pore wall respectively larger and smaller than the spatial range of the interactions which contribute to the rotational potential for the methyl groups. We have estimated a distance of 7 Amstrong as a lower limit of the interaction range, beyond the typical nearest-neighbour distance between centers-of-mass (4.7 Amstrong).Comment: 5 pages, 3 figures. To be published in European Physical Journal E Direct. Proceedings of the 2nd International Workshop on Dynamics in Confinemen

Morbidité et mortalité après adénomectomies prostatiques par voie transvésicale au CHU Kara (Togo)

No Abstrac

Prostate cancer revealed by skin metastasis: A case report in black African man

AbstractIntroductionProstate cancer is the most common male malignancy in Togo. Most patients present with advanced and metastatic disease. Skin metastasis from prostate cancer is very rare and it occurs late and often with a poor prognosis. We report a case in a 52-year-old Togolese man where the skin lesions reveal the disease and with a good prognosis three years after treatment.ObservationIn 2012, a 52-year-old man presented in dermatology with multiple painless skin nodules on his chest. He did not have lower urinary tract symptoms The biopsy of the skin lesion (three nodules) showed a metastasis of adenocarcinoma type tumor and tumor markers performed pointed toward prostate as primary site. In urology a diagnostic biopsy (12 cores) of prostate revealed a high-grade (Gleason grade 4+4) adenocarcinoma. We performed a bilateral orchiectomy as androgen deprivation therapy and one month after this treatment the skin lesions have disappeared.ConclusionSkin metastasis of prostate cancer is rare and their recognition remains poor among practitioners requiring biopsy of the lesions. The prognosis could be better in newly diagnosed prostate cancer

Circulation of human influenza viruses and emergence of Oseltamivir-resistant A(H1N1) viruses in Cameroon, Central Africa

<p>Abstract</p> <p>Background</p> <p>While influenza surveillance has increased in most developing countries in the last few years, little influenza surveillance has been carried out in sub-Saharan Africa and no information is available in Central Africa. The objective of this study was to assess the prevalence of influenza viruses circulating in Yaounde, Cameroon and determine their antigenic and genetic characteristics.</p> <p>Methods</p> <p>Throat and/or nasal swabs were collected from November 2007 to October 2008 from outpatients with influenza-like illness (ILI) in Yaounde, Cameroon and analyzed by two different techniques: a one-step real time reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation in MDCK cells. Typing and subtyping of virus isolates was performed by hemagglutination inhibition (HI), and viruses were sent to the WHO Collaborating Centre in London, UK for further characterization and analyses of antiviral resistance by enzyme inhibition assay and nucleotide sequencing.</p> <p>Results</p> <p>A total of 238 patients with ILI were sampled. During this period 70 (29%) samples were positive for influenza by RT-PCR, of which only 26 (11%) were positive by virus isolation. By HI assay, 20 of the 26 isolates were influenza type A (10 H3N2 and 10 H1N1) and 6 were influenza type B (2 B/Victoria/2/87 lineage and 4 B/Yagamata/16/88 lineage). Seven (70%) of the H1N1 isolates were shown to be resistant to oseltamivir due to a H275Y mutation.</p> <p>Conclusions</p> <p>This study confirmed the circulation of influenza A(H1N1), A(H3N2) and B viruses in the human population in Central Africa and describes the emergence of oseltamivir-resistant A(H1N1) viruses in Central Africa.</p

Unveiling thermal transitions of polymers in subnanometre pores

The thermal transitions of confined polymers are important for the application of polymers in molecular scale devices and advanced nanotechnology. However, thermal transitions of ultrathin polymer assemblies confined in subnanometre spaces are poorly understood. In this study, we show that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry. The pore size and surface functionality of PCPs can be tailored to study the transition behaviour of confined polymers. The transition temperature of PEG in PCPs was determined by manipulating the pore size and the pore–polymer interactions. It is also striking that the transition temperature of the confined PEG decreased as the molecular weight of PEG increased

Environmental Predictors of Seasonal Influenza Epidemics across Temperate and Tropical Climates

Human influenza infections exhibit a strong seasonal cycle in temperate regions. Recent laboratory and epidemiological evidence suggests that low specific humidity conditions facilitate the airborne survival and transmission of the influenza virus in temperate regions, resulting in annual winter epidemics. However, this relationship is unlikely to account for the epidemiology of influenza in tropical and subtropical regions where epidemics often occur during the rainy season or transmit year-round without a well-defined season. We assessed the role of specific humidity and other local climatic variables on influenza virus seasonality by modeling epidemiological and climatic information from 78 study sites sampled globally. We substantiated that there are two types of environmental conditions associated with seasonal influenza epidemics: “cold-dry” and “humid-rainy”. For sites where monthly average specific humidity or temperature decreases below thresholds of approximately 11–12 g/kg and 18–21°C during the year, influenza activity peaks during the cold-dry season (i.e., winter) when specific humidity and temperature are at minimal levels. For sites where specific humidity and temperature do not decrease below these thresholds, seasonal influenza activity is more likely to peak in months when average precipitation totals are maximal and greater than 150 mm per month. These findings provide a simple climate-based model rooted in empirical data that accounts for the diversity of seasonal influenza patterns observed across temperate, subtropical and tropical climates

Influenza activity in Cambodia during 2006-2008

<p>Abstract</p> <p>Background</p> <p>There is little information about influenza disease among the Cambodian population. To better understand the dynamics of influenza in Cambodia, the Cambodian National Influenza Center (NIC) was established in August 2006. To continuously monitor influenza activity, a hospital based sentinel surveillance system for ILI (influenza like illness) with a weekly reporting and sampling scheme was established in five sites in 2006. In addition, hospital based surveillance of acute lower respiratory infection (ALRI) cases was established in 2 sites.</p> <p>Methods</p> <p>The sentinel sites collect weekly epidemiological data on ILI patients fulfilling the case definition, and take naso-pharyngeal specimens from a defined number of cases per week. The samples are tested in the Virology Unit at the Institut Pasteur in Phnom Penh. From each sample viral RNA was extracted and amplified by a multiplex RT-PCR detecting simultaneously influenza A and influenza B virus. Influenza A viruses were then subtyped and analyzed by hemagglutination inhibition assay. Samples collected by the ALRI system were tested with the same approach.</p> <p>Results</p> <p>From 2006 to 2008, influenza circulation was observed mainly from June to December, with a clear seasonal peak in October shown in the data from 2008.</p> <p>Conclusion</p> <p>Influenza activity in Cambodia occurred during the rainy season, from June to December, and ended before the cool season (extending usually from December to February). Although Cambodia is a tropical country geographically located in the northern hemisphere, influenza activity has a southern hemisphere transmission pattern. Together with the antigenic analysis of the circulating strains, it is now possible to give better influenza vaccination recommendation for Cambodia.</p

Structural characterization of a crude oil by one and two dimensional nuclear magnetic resonance spectroscopy

News methods were developped for the structural characterization by NMR of narrow distillation cuts of a crude oil. They allowed the calculation of most, but not all, of the average molecular parameters of these cuts. The results are intended to be used in the simulation of the thermophysical properties of the fluid

Premelting in orientationally disordered molecular crystals. A re-appraisal

International audienc

Grain boundary premelting in crystalline benzene as studied by proton N.M.R.

The phenomenon of premelting has been investigated by proton n.m.r. in polycrystalline benzene of various purity. Our results suggest that premelting initiates at grain boundaries. The exact nature of the molten domains near the standard melting point is not yet clear but is presumably analogous to what is obtained in the surface melting experiments, i.e. a « strongly correlated interface liquid ».Le phénomène de préfusion dans le benzène polycristallin de pureté variable a été étudié par r.m.n. du proton. Nos résultats suggèrent que la préfusion débute aux joints de grains. La nature exacte des domaines fondus n'est pas encore très claire mais il semble que l'on observe un liquide d'interface très corrélé, comme les auteurs qui étudient la fusion de surface