Les auteurs présentent un nouveau type de convertisseur continu-continu à étage intermédiaire utilisant les propriétés des circuits résonnants. Une étude analytique des convertisseurs à résonance permet de décrire le fonctionnement statique et d'évaluer les caractéristiques de ces convertisseurs. La modélisation a été effectuée et met en relief le comportement dynamique de ces convertisseurs. Cette étude en petits signaux a conduit à une représentation sous forme de fonctions de transfert faisant intervenir les variables de sorties (tension) et de contrôle (fréquence de découpage). L'expérimentation de tels convertisseurs a confirmé l'étude analytique et la validité des relations dynamiques
Standard parenteral nutrition solutions are mixtures comprising interacting components that may degrade themselves over time. The objective of this study was to investigate the physicochemical and microbiological stability of a hospital preparation for parenteral nutrition in neonatology. The analyses were performed throughout the storage of the preparations at 2–8 °C (up to 4 months). The extent of stability was based on the determination of amino acids dosage, visual and physicochemical properties (glucose and electrolytes concentrations, pH and osmolality measurements, particle counting) and microbiological analysis (sterility test). A thermal degradation of ascorbic acid was conducted to evaluate the antioxidant properties of the parenteral mixture. Physicochemical and microbiological controls were found to comply with the specifications. Amino acids showed a good stability throughout the 4months storage except for cysteine, which was progressively degraded to cystine, conferring a yellow coloration to parenteral solutions. Parenteral nutrition standards solutions remain stable for 4 months at 2–8 °C, ensuring safe administration in preterm infants.
UITTREKSEL Suid-Afrikaanse leerders se ontoereikende wiskundeprestasie is 'n bron van kommer vir elkeen wat betrokke is by leerfasilitering in wiskunde. Belanghebbendes soek ernstig na moontlike wyses waarop leerders se insig rakende en prestasie in wiskunde verbeter An important conclusion is that although the Harmony South African Mathematics Olympiad accomplishes its goal, it still does not reach as many learners and educators as one would hope. The ideals of the Harmony South African Mathematics Olympiad will probably only be realised if all schools are provided with proper facilities and if the standard of mathematics education is simultaneously improved on a national level. It is therefore vital that all interested parties discuss and reassess this matter promptly and incisively. AGTERGRONDDaar bestaan in 'n redelike mate konsensus dat wiskundeolimpiades 'n uitnemende meganisme is, nie slegs om talentvolle leerders te identifiseer nie, maar ook om leerders betrokke te maak by wiskunde-olimpiades enersyds en wiskunde en wiskundige studierigtings in die algemeen.1 Tewens, Alexander 1 voer aan dat wiskunde-olimpiades oor die beste baanrekord beskik wat metodes betref om begaafde wiskundeleerders te identifiseer. Teen die verwysingsraamwerk wat in die volgende aantal paragrawe aangebied word, maak dit dus sin om bestek te neem van enkele fasette van die Harmony Suid-Afrikaanse Wiskunde-Olimpiade, om enkele tendense uit te lig en om te herbesin oor moontlike maniere waarop hierdie olimpiade verder kan bydra tot die ontwikkeling van wiskundetalent by leerders en -vaardighede by alle leerders en opvoeders in SuidAfrika. Nieteenstaande die feit dat opvoeding en opleiding in postapartheid-Suid-Afrika getransformeer word, manifesteer 'n onaanvaarbare hoë druipsyfer steeds in wiskunde op skool. 2, 3Die tendens is ook sigbaar in tersiêre opleiding: Slegs 20% van alle Suid-Afrikaanse tersiêre studente voltooi hul studies, met studente in die wetenskaplike en handelswetenskaplike velde wat blyke gee van die hoogste druipsyfers. 4In Suid-Afrika is daar verder 'n groot gaping tussen die kwaliteit van onderwys en die prestasies van wit en swart a studente in wiskunde. 5,6 Aangesien graad 12-resultate steeds grootliks bepaal of 'n leerder aanvaar word vir gesogte studie-1 Persoon aan wie korrespondensie gerig moet word. Die outeurs spreek hiermee hul waardering uit teenoor dr. H. de Roos vir sy hulp met die statistiese verwerking van die data. Die outeurs bedank ook Harmony Gold Mining, asook al die leerders en opvoeders wat aan die studie deelgeneem het.
BackgroundSince the March 2015 directive publication of the country’s health department, parenteral nutrition (PN) must be produced by hospital pharmacists, under pharmaceutical responsibility. How to manage closing periods of the hospital pharmacy unit (HPU) to manufacture individualised formulation of paediatric PN (IFPN) for newborns.PurposeSummarise the state of management of HPU closure for IFPN through a survey of hospitals in the country in 2017.Material and methodsA survey with oriented questions according to answers was developed. This form was sent by email to the hospital pharmacist.After general questions (Healthcare Establishment (HE) type: General Hospital Centre (GHC) or University Hospital Centre (UHC), maternity level (classed 1 to 3 in our country)), the first part approaches alternative solutions in case of no production during the HPU closing period. Then, the second part, for IFPN production, which answers different questions concerning formulation validation, production and controls.ResultsNineteen received responses were studied. For HE type: 17 UHC (89.5%) and two GHC (10.5%), all had a maternity (whose 95% with neonatal intensive care unit, level 3 (n=18)). Twelve of 17 pharmacists (65%) report no IFPN during the closing period. A major alternative solution is IFPN, which wereproduced before the closure period (e.g. on Friday). While 16% (n=2) of HE reported using only IFPN, 83.3% (n=10) use IFPN and standardised PN (SPN) and 25% (n=3) associated IFPN, SPN, and industrial PN (with or without supplementation).For other HE (35%, n=7) with PN activity on the weekend, 57.1% (n=4) produces IFPN at HPU and 42.9% (n=3) in the paediatric care unit. Only IFPN which were produced at HPU are formulations checked by a pharmacist. Then, for controls, everybody declared a double visual control during production, 71% realised analytics assays (mainly Na and K), 40% performed microbiologic assay and 60% (n=4) labelling check and mirage. Pharmaceutical liberation is reported on 80%.ConclusionThese results based on statements remain to be analysed cautiously but the trend is no production of IFPN on the weekend. In case of preparations, controls on final product allows the provision of a quality product for newborns. Compliance with the directive remains difficult, perhaps a consensus around SPN with paediatric physicians will make it possible to avoid PN production activity outside the opening period of HPU.References and/or AcknowledgementsPharmacists who had completed survey.No conflict of interest
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