Development of a steady state simulation code for klystrons

The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and it allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from theory and from another code. Effects of space charge forces in the drift tubes are also evaluated

Development of a steady state simulation code for klystrons

The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and it allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from theory and from another code. Effects of space charge forces in the drift tubes are also evaluated

Electroencephalogram and somatosensory evoked potential evaluation for good and poor neurological prognosis after cardiac arrest: A prospective multicenter cohort trial (ProNeCA)

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Re-think of a business model: A case boosted by COVID-19

2020 was suddenly struck by a pandemic caused by the spread of the new COVID-19. It is important to analyse the current business model to remain competitive after COVID-19, especially in the industry 4.0. The main goal of the research is to re-think, where necessary, the business model through the Canvas framework for IRRITEC S.p.A. As a main conclusion, and based on the example of IRRITEC S.p.A., the research shows that companies need to change some aspects in their business models in order to adapt to the new reality.2020 foi subitamente atingido por uma pandemia causada pela propagação da nova COVID-19. É importante analisar o atual modelo de negócios para permanecer competitivo após a COVID-19, especialmente na indústria 4.0. O objetivo principal da dissertação é repensar, onde necessário, o modelo de negócio através da estrutura de Canvas da IRRITEC S.p.A. Como conclusão principal, e com base no exemplo da IRRITEC S.p.A., a investigação mostra que as empresas precisam de alterar alguns aspectos dos seus modelos de negócio para se adaptarem à nova realidade

Influence of PRF in the healing of bone and gingival tissues. Clinical and histological evaluations

INTRODUCTION: The healing of bone tissues around dental implants is based primarily on a correct osseointegration. BACKGROUND: Typically, implants stability and peri-implant tissues health are anticipated to decrease during the early weeks of healing; this is followed by an increase in stability. AIM: The aim of the present study is to assess a predictable protocol in order to increase the peri-implant tissues maintenance around post-extractive dental implants, thanks to the use of Platelet-Rich Fibrin (PRF) membrane. MATERIALS AND METHODS: This is a retrospective observational study of 127 tapered dental implants placed in the immediate post-extraction sites of maxillary bone of 59 patients. Atraumatic dental extraction and flapless implant surgery was performed in all reported cases. The cortical bone position relative to the implant reference point was evaluated at implant placement and 10 to 24 months following implantology. The gap between bone tissue and the implant surface was measured up to a maximum of 3 mm. After placing implants we have filled the surgical site with a PRF gel, so as to fill the gap between bone tissue and the implant surface, and then we have covered the surgical site with a PRF membrane, so as to coat the gap between the alveolar crest and the implant. RESULTS: In all cases, we observed the complete covering of the dental implants, with newly formed soft tissue of variable thickness between 1 and 3 mm. Cortical bone adaptation from the time of implant placement up to 30 months following prosthetic restoration ranged from 0.4 mm to 1.7 mm. CONCLUSIONS: Our study showed a series of successful rehabilitations, with post-extraction implantology technique, in 99.8 percent of cases, despite the success rates in the medium and long-term post-extraction implantology reported in the literature range between 92.7 percent and 98.0 percent. Long-term maintenance of crestal bone and the rapid healing of soft tissue dimension with maintenance of peri-implant papilla were observed as outcomes after post-extractive implants insertion

Potential use of human periapical cyst-mesenchymal stem cells (hPCy-MSCs) as a novel stem cell source for regenerative medicine applications

Mesenchymal stem cells (MSCs) are attracting growing interest by the scientific community due to their huge regenerative potential. Thus, the plasticity of MSCs strongly suggests the utilization of these cells for regenerative medicine applications. The main issue about the clinical use of MSCs is related to the complex way to obtain them from healthy tissues; this topic has encouraged scientists to search for novel and more advantageous sources of these cells in easily accessible tissues. The oral cavity hosts several cell populations expressing mesenchymal stem cell like-features, furthermore, the access to oral and dental tissues is simple and isolation of cells is very efficient. Thus, oral-derived stem cells are highly attractive for clinical purposes. In this context, human periapical cyst mesenchymal stem cells (hPCy-MSCs) exhibit characteristics similar to other dental-derived MSCs, including their extensive proliferative potential, cell surface marker profile and the ability to differentiate into various cell types such as osteoblasts, adipocytes and neurons. Importantly, hPCy-MSCs are easily collected from the surgically removed periapical cysts; this reusing of biological waste guarantees a smart source of stem cells without any impact on the surrounding healthy tissues. In this review, we report the most interesting research topics related to hPCy-MSCs with a newsworthy discussion about the future insights. This newly discovered cell population exhibits interesting and valuable potentialities that could be of high impact in the future regenerative medicine applications

The regenerative medicine in oral and maxillofacial surgery: The most important innovations in the clinical application of mesenchymal stem cells

Regenerative medicine is an emerging field of biotechnology that combines various aspects of medicine, cell and molecular biology, materials science and bioengineering in order to regenerate, repair or replace tissues.The oral surgery and maxillofacial surgery have a role in the treatment of traumatic or degenerative diseases that lead to a tissue loss: frequently, to rehabilitate these minuses, you should use techniques that have been improved over time. Since 1990, we started with the use of growth factors and platelet concentrates in oral and maxillofacial surgery; in the following period we start to use biomaterials, as well as several type of scaffolds and autologous tissues. The frontier of regenerative medicine nowadays is represented by the mesenchymal stem cells (MSCs): overcoming the ethical problems thanks to the use of mesenchymal stem cells from adult patient, and with the increasingly sophisticated technology to support their manipulation, MSCs are undoubtedly the future of medicine regenerative and they are showing perspectives unimaginable just a few years ago. Most recent studies are aimed to tissues regeneration using MSCs taken from sites that are even more accessible and rich in stem cells: the oral cavity turned out to be an important source of MSCs with the advantage to be easily accessible to the surgeon, thus avoiding to increase the morbidity of the patient.The future is the regeneration of whole organs or biological systems consisting of many different tissues, starting from an initial stem cell line, perhaps using innovative scaffolds together with the nano-engineering of biological tissues

Cells isolated from human periapical cysts express mesenchymal stem cell-like properties

We provide a detailed description of mesenchymal stem cells (MSCs) isolated from human periapical cysts, which we have termed hPCy-MSCs. These cells have a fibroblast-like shape and adhere to tissue culture plastic surfaces. hPCy-MSCs possess high proliferative potential and self-renewal capacity properties. We characterised the immunophenotype of hPCy-MSCs (CD73+, CD90+, CD105+, CD13+, CD29+, CD44+, CD45-, STRO-1+, CD146+) by flow cytometry and immunofluorescence. hPCy-MSCs possess the potential to differentiate into osteoblast- and adipocyte-like cells in vitro. Multi-potentiality was evaluated with culture-specific staining and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis for osteo/odontogenic and adipogenic markers. This is the first report to indicate that human periapical cysts contain cells with MSC-like properties. Taken together, our findings indicate that human periapical cysts could be a rich source of MSCs. © Ivyspring International Publisher