Prikaz stanja silicijevih MOS upravljanih učinskih sklopova i PiN ispravljača

Revolutionary advances and developments have been made in power semiconductor device technologies during the last decades which have allowed the improvement of power electronic systems in terms of their efficiency and reliability. The advent of MOS-gated power switches such as the power MOSFET and the IGBT showing high input impedance has been a real breakthrough in the design and fabrication of power electronic systems. This paper reviews the recent progress in the development of Si MOS-gated power devices and rectifiers. The evolution of these devices’ technologies together with the introduction of revolutionary device concepts is also discussed. Concretely, the introduction of trench technologies for power MOSFETs and the use of the super-junction concept for breaking the 1D-silicon limit are highlighted. Developments in IGBTs such as those based on the use of thin wafers and strategies for optimising the plasma distribution in PT IGBTs during the on-state are also addressed. Finally, advances in PiN diode technologies including new concepts for both the anode and the cathode structures are also reviewed. These approaches have allowed the reduction of the PiN total losses and a soft reverse recovery behaviour, leading to a more rugged device.U posljednjim desetljećima svjedočimo razvoju sustava učinske elektronike u pogledu povećanja efikasnosti i pouzdanosti. Napredak je omogućen zahvaljujući izvanrednom napredku koji je postignut na području učinskih poluvodiča. Pojava MOS upravljanih učinskih sklopova s visokom ulaznom impedancijom, kao što su MOSFET i IGBT, rezultirao je probojem u projektiranju i proizvodnji sustava učinske elekronike. Ovaj članak daje uvid u napredak koji je u posljednje vrijeme ostvaren u razvoju silicijeve MOS upravljane učinske elektronike i ispravljača. Uz dosadašnji razvoj tehnologije navedenih komponenata, u članku je uključen i osvrt na revolucionarne koncepte budućeg razvoja. Konkretno, u radu su objašnjene tehnologija rova za MOSFET i korištenje koncepta super spoja za probijanje granice jednodimenzionalnog silicija. Razmatrana su i poboljšanja IGBT-ova koja se baziraju na uporabi tankih pločica a strategijama optimiranja distribucije plazme u PT IGBT-ovima za vrijeme aktivnog stanja. Konačno, prikazan je i napredak u tehnologiji PiN dioda koji uključuje nove strukturalne koncepte katode i anode. Ovi pristupi su omogućili smanjenje ukupnih gubitaka PiN diode i blagu dinamiku reverznog oporavka, što rezultira povećanjem robusnosti sklopa

Systematic Deletion of Homeobox Genes in Podospora anserina Uncovers Their Roles in Shaping the Fruiting Body

Higher fungi, which comprise ascomycetes and basidiomycetes, play major roles in the biosphere. Their evolutionary success may be due to the extended dikaryotic stage of their life cycle, which is the basis for their scientific name: the Dikarya. Dikaryosis is maintained by similar structures, the clamp in basidiomycetes and the crozier in ascomycetes. Homeodomain transcription factors are required for clamp formation in all basidiomycetes studied. We identified all the homeobox genes in the filamentous ascomycete fungus Podospora anserina and constructed deletion mutants for each of these genes and for a number of gene combinations. Croziers developed normally in these mutants, including those with up to six deleted homeogenes. However, some mutants had defects in maturation of the fruiting body, an effect that could be rescued by providing wild-type maternal hyphae. Analysis of mutants deficient in multiple homeogenes revealed interactions between the genes, suggesting that they operate as a complex network. Similar to their role in animals and plants, homeodomain transcription factors in ascomycetes are involved in shaping multicellular structures

Echocardiography practice, training and accreditation in the intensive care: document for the World Interactive Network Focused on Critical Ultrasound (WINFOCUS)

Echocardiography is increasingly used in the management of the critically ill patient as a non-invasive diagnostic and monitoring tool. Whilst in few countries specialized national training schemes for intensive care unit (ICU) echocardiography have been developed, specific guidelines for ICU physicians wishing to incorporate echocardiography into their clinical practice are lacking. Further, existing echocardiography accreditation does not reflect the requirements of the ICU practitioner. The WINFOCUS (World Interactive Network Focused On Critical UltraSound) ECHO-ICU Group drew up a document aimed at providing guidance to individual physicians, trainers and the relevant societies of the requirements for the development of skills in echocardiography in the ICU setting. The document is based on recommendations published by the Royal College of Radiologists, British Society of Echocardiography, European Association of Echocardiography and American Society of Echocardiography, together with international input from established practitioners of ICU echocardiography. The recommendations contained in this document are concerned with theoretical basis of ultrasonography, the practical aspects of building an ICU-based echocardiography service as well as the key components of standard adult TTE and TEE studies to be performed on the ICU. Specific issues regarding echocardiography in different ICU clinical scenarios are then described