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Spera, M.,Corso, D.,Di Franco, S.,Greco, G.,Severino, A.,Fiorenza, P.,Giannazzo, F.,Roccaforte, F. Elsevier 2019 Materials science in semiconductor processing Vol.93 No.-
<P><B>Abstract</B></P> <P>This work reports on the effect of high temperature annealing on the electrical properties of p-type implanted 4H-SiC. Ion implantations of Aluminum (Al) at different energies (30–200 keV) were carried out to achieve 300 nm thick acceptor box profiles with a concentration of about 10<SUP>20</SUP> at/cm<SUP>3</SUP>. The implanted samples were annealed at high temperatures (1675–1825 °C). Morphological analyses of the annealed samples revealed only a slight increase of the surface roughness RMS up to 1775 °C, while this increase becomes more significant at 1825 °C (RMS = 1.2 nm). Room temperature Hall measurements resulted in a hole concentration in the range 0.65–1.34 × 10<SUP>18</SUP>/cm<SUP>3</SUP> and mobility values in the order of 21–27 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>. The temperature dependent electrical measurements allowed to estimate an activation energy of the Al-implanted specie of about 110 meV (for the post-implantation annealing at 1675 °C) and a fraction of active p-type Al-dopant ranging between 39% and 56%. The results give useful indications for the fabrication of 4H-SiC JBS and MOSFETs.</P>
Divergent reprogramming routes lead to alternative stem-cell states
Tonge, Peter D.,Corso, Andrew J.,Monetti, Claudio,Hussein, Samer M. I.,Puri, Mira C.,Michael, Iacovos P.,Li, Mira,Lee, Dong-Sung,Mar, Jessica C.,Cloonan, Nicole,Wood, David L.,Gauthier, Maely E.,Korn, Nature Publishing Group, a division of Macmillan P 2014 Nature Vol.516 No.7530
Pluripotency is defined by the ability of a cell to differentiate to the derivatives of all the three embryonic germ layers: ectoderm, mesoderm and endoderm. Pluripotent cells can be captured via the archetypal derivation of embryonic stem cells or via somatic cell reprogramming. Somatic cells are induced to acquire a pluripotent stem cell (iPSC) state through the forced expression of key transcription factors, and in the mouse these cells can fulfil the strictest of all developmental assays for pluripotent cells by generating completely iPSC-derived embryos and mice. However, it is not known whether there are additional classes of pluripotent cells, or what the spectrum of reprogrammed phenotypes encompasses. Here we explore alternative outcomes of somatic reprogramming by fully characterizing reprogrammed cells independent of preconceived definitions of iPSC states. We demonstrate that by maintaining elevated reprogramming factor expression levels, mouse embryonic fibroblasts go through unique epigenetic modifications to arrive at a stable, Nanog-positive, alternative pluripotent state. In doing so, we prove that the pluripotent spectrum can encompass multiple, unique cell states.
Genome-wide characterization of the routes to pluripotency
Hussein, Samer M. I.,Puri, Mira C.,Tonge, Peter D.,Benevento, Marco,Corso, Andrew J.,Clancy, Jennifer L.,Mosbergen, Rowland,Li, Mira,Lee, Dong-Sung,Cloonan, Nicole,Wood, David L. A.,Munoz, Javier,Midd Nature Publishing Group, a division of Macmillan P 2014 Nature Vol.516 No.7530
Somatic cell reprogramming to a pluripotent state continues to challenge many of our assumptions about cellular specification, and despite major efforts, we lack a complete molecular characterization of the reprograming process. To address this gap in knowledge, we generated extensive transcriptomic, epigenomic and proteomic data sets describing the reprogramming routes leading from mouse embryonic fibroblasts to induced pluripotency. Through integrative analysis, we reveal that cells transition through distinct gene expression and epigenetic signatures and bifurcate towards reprogramming transgene-dependent and -independent stable pluripotent states. Early transcriptional events, driven by high levels of reprogramming transcription factor expression, are associated with widespread loss of histone H3 lysine 27 (H3K27me3) trimethylation, representing a general opening of the chromatin state. Maintenance of high transgene levels leads to re-acquisition of H3K27me3 and a stable pluripotent state that is alternative to the embryonic stem cell (ESC)-like fate. Lowering transgene levels at an intermediate phase, however, guides the process to the acquisition of ESC-like chromatin and DNA methylation signature. Our data provide a comprehensive molecular description of the reprogramming routes and is accessible through the Project Grandiose portal at http://www.stemformatics.org.
Francesco Bussu,Mario Rigante,Veronica Giglia,Giovanni Bastanza,Eugenio De Corso,Giovanni Almadori,Gaetano Paludetti 대한이비인후과학회 2014 Clinical and Experimental Otorhinolaryngology Vol.7 No.2
Objectives. We analyzed the outcomes following clinical management of parotid masses that were determined to be malig- nant tumors after parotidectomy. Methods. We evaluated data from 70 patients with parotid malignancies between November 1994 and December 2005. Results. Among salivary histotypes (n=49), the most significant prognostic parameter was cT4 stage at diagnosis (P=0.0055, log-rank) both for clinical involvement of the facial nerve and for invasion of other structures. The main cause of cancer-related death was a distant metastasis. Conclusion. The present series confirms that the main prognostic parameter in salivary parotid malignancies was cT4 clas- sification at diagnosis, often due to clinical involvement of the facial nerve. The oncological outcome of salivary ma- lignancies was influenced by distant metastasis more than most other head and neck sites. We recommend dissecting and preserving the functioning VIIth cranial nerve during surgery for parotid malignancies.