Etude de quelques caractéristiques physico chimiques du filtrat toxique de Phoma sabdariffae Sacc., agent pathogène de la roselle

La roselle est une plante maraîchère de la famille des Malvaceae, principalement exploitée au Gabon pour des raisons alimentaires ou thérapeutiques. Cette plante est victime d’une sévère pourriture provoquée par un champignon Deutéromycète, Phoma sabdariffae Sacc., dont l’action repose sur l’excrétion de substances toxiques. Le présent travail a été conçu pour étudier quelques caractéristiques physico chimiques de ces productions toxiques. Les paramètres évalués étaient la thermosensibilité, la photosensibilité, la composition biochimique et le fractionnement chromatographique. Les résultats obtenus ont révélé que le filtrat toxique de Ph. sabdariffae se conservait relativement bien à 0°C, mais perdait sa toxicité aux températures élevées, devenant totalement inactif au delà de 50°C. Il est photosensible, riche en composés  glucidiques, protéiques et phénoliques. Sa toxicité paraît uniquement liée aux composés phénoliques qui laissent découvrir après fractionnement chromatographique, 4 fractions, dont 2 actives, F1 et F4, avec des caractéristiques respectivement proches de celles de la brefeldine A et de la cytochalasine B.Jamaican sorrel is a Malvaceae plant, mainly cultivated in Gabon for diet or therapeutic reasons. This crop is attacked by Phoma sabdariffae Sacc., an imperfect pathogenic fungi who acts by producing toxic compounds. Objective of this work is studying the physico chemical characteristics of these toxic compounds. Measured parameters were temperature and luminosity sensibility, biochemical and chromatogrphy content. The resultsshow that Phoma sabdariffae Sacc. culture filtrate stays stable at 0 °C ; it is both thermosensible and photosensible, and contains glucidic, proteic and phenolic compounds. Its toxicity is due to the phenolic compounds that possess 2 actives fractions F1 and F4, with physico chemical characteristics close to those of brefeldine A and cytochalasine B.Mots clés : Phoma sabdariffae Sacc., roselle, filtrat, polyphénols, fractions actives, Gabon

Similarity Solutions for Boundary Layer Flows on a Moving Surface in Non-Newtonian Power-Law Fluids

A similarity analysis of the boundary layer flow caused by the motion of a semi-infinite flat sulface in a non-Newtonian power-law fluid at rest is made in this paper. These similar solutions fall into two categories: similarity solutions corresponding to steady boundary layers over moving surfaces and similarity solutions corresponding to unsteady boundary layers past moving flat surfaces, respectively. Except in the special case n = 1/2 (pseudoplastic) and n = 1 (Newtonian) fluids, solutions of the first category problems must be obtainednumerically. However, for the second category analytical solutions are possible for a large class of pseudoplasticfluids (n < 1), including the case of a Newtonianfluid (n = 1)

Numerical simulation of pullout behavior of embedded suction anchors in clay

As the offshore wind power tends to locate farther from the coast for efficient generation of electricity,\ud the interest of foundation systems of which construction sequence is economical and convenient under deep water\ud circumstance is increasing. Mooring anchor system has been utilized as one of the most popular ways for anchoring of\ud vessels or floating structures, and various types of anchor and mooring system have been investigated for large\ud structures under diverse loading condition. In this paper, the pullout behavior of the modified embedded suction anchor\ud (ESA) is studied using numerical analysis. The behavior of the embedded suction anchor is simulated using finite\ud element method, and Adaptive Meshing (AM) technique approach incorporated in Abaqus/Explicit is applied to\ud simulate the large deformation of soil caused by continuous pullout of anchor. The three dimensional modeling is\ud performed to duplicate the round body shape with flanges of the embedded suction anchor. The anchor is assumed as\ud rigid body and clay is considered as a linear elastic-perfectly plastic soil model with a Tresca yield criterion. The\ud pullout capacities after different initial rotations show similar results with the maximum horizontal pullout capacity and\ud the load inclination of 30?? or 40?? at the bottom point of the ESA has an advantage in that reduced pullout load can rotate\ud the ESA

Superpartner Solutions of a BPS Monopole in Noncommutative Space

We construct U(2) BPS monopole superpartner solutions in N=2 non-commutative super Yang-Mills theory. Calculation to the second order in the noncommutative parameter $\theta$ shows that there is no electric quadrupole moment that is expected from the magnetic dipole structure of noncommtative U(2) monopole. This might give an example of the nature of how supersymmetry works not changing between the commutative and noncommutative theories.Comment: 8 page

Particle Emission-dependent Timing Noise of Pulsars?

Though pulsars spin regularly, the differences between the observed and predicted ToA (time of arrival), known as "timing noise", can still reach a few milliseconds or more. We try to understand the noise in this paper. As proposed by Xu & Qiao in 2001, both dipole radiation and particle emission would result in pulsar braking. Accordingly, possible fluctuation of particle current flow is suggested here to contribute significant ToA variation of pulsars. We find that the particle emission fluctuation could lead to timing noise which can't be eliminated in timing process, and that a longer period fluctuation would arouse a stronger noise. The simulated timing noise profile and amplitude are in accord with the observed timing behaviors on the timescale of years.Comment: 6 pages, 2 figures. (Accepted by Chin. Phys. Lett.

Purifying single photon emission from a CdSe/CdS colloidal quantum dot

Colloidal quantum dots are robust and flexible single photon emitters for room-temperature applications, but their purity is strongly reduced at high pump powers, due to multiexcitonic emission which cannot be easily filtered due to the photo-luminescence spectral broadening at room temperature. Giant-shell quantum dots feature a large blueshift of the biexciton spectrum due to electron-hole wave function engineering and piezoelectric charge separation, which can be exploited for spectral separation of the single exciton from the multiexciton emission. Here, by spectral filtering, we show that we can recover an excellent single-photon emission, with $g_2{(0)} < 0.05$ (resolution limited), even at high pump powers above saturation of the exciton emission. The bright and pure single-photon generation shown here has important applications in quantum information technology and random-number generation

Patient safety in developing countries: retrospective estimation of scale and nature of harm to patients in hospital

OBJECTIVE: To assess the frequency and nature of adverse events to patients in selected hospitals in developing or transitional economies. DESIGN: Retrospective medical record review of hospital admissions during 2005 in eight countries. SETTING: Ministries of Health of Egypt, Jordan, Kenya, Morocco, Tunisia, Sudan, South Africa and Yemen; the World Health Organisation (WHO) Eastern Mediterranean and African Regions (EMRO and AFRO), and WHO Patient Safety. PARTICIPANTS: Convenience sample of 26 hospitals from which 15,548 patient records were randomly sampled. MAIN OUTCOME MEASURES: Two stage screening. Initial screening based on 18 explicit criteria. Records that screened positive were then reviewed by a senior physician for determination of adverse event, its preventability, and the resulting disability. RESULTS: Of the 15,548 records reviewed, 8.2% showed at least one adverse event, with a range of 2.5% to 18.4% per country. Of these events, 83% were judged to be preventable, while about 30% were associated with death of the patient. About 34% adverse events were from therapeutic errors in relatively non-complex clinical situations. Inadequate training and supervision of clinical staff or the failure to follow policies or protocols contributed to most events. CONCLUSIONS: Unsafe patient care represents a serious and considerable danger to patients in the hospitals that were studied, and hence should be a high priority public health problem. Many other developing and transitional economies will probably share similar rates of harm and similar contributory factors. The convenience sampling of hospitals might limit the interpretation of results, but the identified adverse event rates show an estimate that should stimulate and facilitate the urgent institution of appropriate remedial action and also to trigger more research. Prevention of these adverse events will be complex and involves improving basic clinical processes and does not simply depend on the provision of more resources

Combining ability analysis in Brassica juncea L. for oil quality traits

This study was conducted in Brassica juncea L. for the determination of good combiners for quality associated traits using 8 x 8 diallel during 2004 - 2005 and 2005 - 2006. Analysis of variance revealed highly significant differences (p 0.01) for all the studied traits. Components of combining ability analysis showed that general combining ability (GCA) was highly significant (p 0.01) for oil percentage (%) and glucosinolates (&#236;Molg-1) whereas the rest were non-significant. Specific combining ability (SCA)effects were highly significant for all traits except for oleic acids. Reciprocal combining ability (RCA) effects were highly significant (p 0.01) for all traits except for oleic acid which was significant at (p 0.05). The SCA effects were higher than RCA for oil %. The GCA effects were of greater magnitude thanthe SCA effects for glucosinolate, erucic acid and protein content. The parental genotypes NUM009, NUM123, NUM105 and NUM117 and their hybrids NUM009x NUM123, NUM103x NUM105, NUM113x NUM124 and NUM103x NUM120 had high GCA and SCA effects, respectively and therefore these could be exploited for further selection of high yielding progenies. The overall study reveals the importance of both additive and non-additive genetic variability suggesting the use of integrated breeding strategies which can efficiently utilize the additive as well as non-additive genetic variability