Prevention and treatment of peri-implant diseases—The EFP S3 level clinical practice guideline

Background: The recently published Clinical Practice Guidelines (CPGs) for the treatment of stages I–IV periodontitis provided evidence-based recommendations for treating periodontitis patients, defined according to the 2018 classification. Peri-implant diseases were also re-defined in the 2018 classification. It is well established that both peri-implant mucositis and peri-implantitis are highly prevalent. In addition, peri-implantitis is particularly challenging to manage and is accompanied by significant morbidity. Aim: To develop an S3 level CPG for the prevention and treatment of peri-implant diseases, focusing on the implementation of interdisciplinary approaches required to prevent the development of peri-implant diseases or their recurrence, and to treat/rehabilitate patients with dental implants following the development of peri-implant diseases. Materials and Methods: This S3 level CPG was developed by the European Federation of Periodontology, following methodological guidance from the Association of Scientific Medical Societies in Germany and the Grading of Recommendations Assessment, Development and Evaluation process. A rigorous and transparent process included synthesis of relevant research in 13 specifically commissioned systematic reviews, evaluation of the quality and strength of evidence, formulation of specific recommendations, and a structured consensus process involving leading experts and a broad base of stakeholders. Results: The S3 level CPG for the prevention and treatment of peri-implant diseases culminated in the recommendation for implementation of various different interventions before, during and after implant placement/loading. Prevention of peri-implant diseases should commence when dental implants are planned, surgically placed and prosthetically loaded. Once the implants are loaded and in function, a supportive peri-implant care programme should be structured, including periodical assessment of peri-implant tissue health. If peri-implant mucositis or peri-implantitis are detected, appropriate treatments for their management must be rendered. Conclusion: The present S3 level CPG informs clinical practice, health systems, policymakers and, indirectly, the public on the available and most effective modalities to maintain healthy peri-implant tissues, and to manage peri-implant diseases, according to the available evidence at the time of publication

BIOFUEL AND HYDROGEN INFLUENCE FOR OPERATION PARAMETERS OF SPARK IGNITION ENGINE / BIODEGALŲ IR VANDENILIO ĮTAKA KIBIRKŠTINIO UŽDEGIMO VARIKLIO VEIKIMO RODIKLIAMS

Paper presents research of efficient and ecological parameters of gasoline engine working with biobuthanol (10% and 20% by volume) and addi-tionaly supplying oxygen and hydrogen (HHO) gas mixture (3.6 l/min), which was obtained from from water by electrolysis. Biobuthanol addition decreases rate of heat release, the combustion temperature and pressure are lower, which has an influence on lower nitrous oxide (NOx) emission in exhaust gases. However, biobuthanol increases carbon monoxide (CO) concentration. Biobuthanol fuel has a simplier molecular structure, therefore the concentration of HC in the exhaust gas is decreasing. Due to lower heating value of biobuthanol fuel and slower combustion process, the engine efficiency decreases and specific fuel consumptions increase. The change of engine energetical indicators due to biobuthanol, can be compensated with advanced ignition angle. Using experimental investigation, it was determined, that negative biobuthanol influence for the combustion process and engine efficient inicators can be compensated also by additional supplied HHO gas, in which the hydrogen element iprove fuel mixture com-bustion. Fuel combustion process analysis was carried out using AVL BOOST software. Experimental research and combustion process numerical simulation showed that using balanced biobuthanol and hydrogen addition, optimal efficient and ecological parameters could be achieved, when engine is working for petrol fuel typical optimal spark timing. Santrauka  Straipsnyje pateikiami kibirkštinio uždegimo variklio energinių ir ekologinių rodiklių tyrimo rezultatai, gauti varikliui veikiant benzino ir biobutanolio (10 % ir 20 % tūrio) mišiniais ir papildomai tiekiant elektrolizės būdu iš vandens išgautą deguonies ir vandenilio (HHO) dujų mišinį (3,6 l/min). Biobutanolio priedas mažina šilumos išsiskyrimo intensyvumą degimo metu, mažėja degimo temperatūra bei slėgis. Tai mažina azoto oksidų (NOx) koncentraciją, tačiau didina anglies viendeginio (CO) koncentraciją išmetamosiose dujose. Dėl paprastesnės biobutanolio molekulinės struktūros ne iki galo sudegusių angliavandenilių (CH) koncentracija deginiuose mažėja. Biobutanolis dėl mažes-nio šilumingumo ir lėtesnio degimo mažina variklio efektyvų sukimo momentą ir didina lyginamąsias degalų sąnaudas. Biobutano-lio paveiktus variklio energinius rodiklius galima iš dalies kompensuoti paankstinus uždegimo paskubos kampą. Eksperimentiniu tyrimu nustatyta, kad neigiamą biobutanolio priedo įtaką degalų degimo procesui ir variklio energiniams rodikliams galima kompensuoti papildomai tiekiant HHO dujas, kuriose esantis vandenilis greitina ir gerina degalų mišinių degimą. AVL BOOST programa atlikta degalų mišinių de-gimo proceso analizė. Įvertinus eksperimentinių tyrimų ir degimo proceso skaitinio modeliavimo rezultatus nustatyta, kad, naudojant sude-rintą biobutanolio ir vandenilio priedą, optimalūs energiniai ir ekologiniai rodikliai gali būti pasiekti varikliui veikiant benzinui optimaliu už-degimo paskubos kampu. Reikšminiai žodžiai: biobutanolis, vandenilis, uždegimo paskubos kampas, energiniai ir ekologiniai rodikliai, skaitinis modeliavimas

Entwicklung eines quasidimensionalen Mehrzonen-Modells zur Optimierung des Emissionsverhaltens und des Kraftstoffverbrauchs direkteinspritzender Dieselmotoren Abschlussbericht

The focus in modern diesel engines is on low fuel consumption and pollutant emissions. Computer modelling serves to reduce costly and time-consuming experiments. Models should have a valid physical basis and use only a few empirical equations in order to make it more generally valid than existing models.Bei der Entwicklung moderner Dieselmotoren liegen Schwerpunkte gleichzeitig auf der Reduzierung des Kraftstoffverbrauches und auf der Reduzierung der Schadstoffemissionen. Rechenmodelle, die beide Groessen zuverlaessig berechnen koennen, tragen dazu bei, die Anzahl von zeit- und kostenintensiven experimentellen Untersuchungen zu reduzieren, und fuehren so zu einer schnelleren Entwicklung von schadstoffarmen und verbrauchsguenstigen Motoren. Das zu entwickelnde Modell soll auf einer abgesicherten physikalischen Basis stehen und mit moeglichst wenigen empirischen Gleichungen auskommen, so dass eine wesentlich verbesserte Allgemeingueltigkeit gegenueber existierenden Modellen erreicht wird. (orig.)Available from TIB Hannover: F01B244 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDeutsche Bundesstiftung Umwelt, Osnabrueck (Germany)DEGerman

Large-eddy simulation of kerosene spray combustion in a model scramjet chamber

Large-eddy simulation (LES) of kerosene spray combustion in a model supersonic combustor with cavity flame holder is carried out. Kerosene is injected through the ceiling of the cavity. The subgrid-scale (SGS) turbulence stress ensor is closed via the Smagorinsky’s eddyviscosity model, chemical source terms are modelled by a finite rate chemistry (FRC) model, and a four-step reduced kerosene combustion kinetic mechanism is adopted. The chamber wallpressure predicted from the LES is validated by experimental data reported in literature. The test case has a cavity length of 77mm and a depth of 8mm. After liquid kerosene is injected through the orifice, most of the droplets are loaded with recirculation fluid momentum inside the cavity. Due to lower velocity of the carrier fluid inside the cavity, sufficient atomization and evaporation take place during the process of droplet transportation, resulting in a rich fuel mixture of kerosene vapour accumulating inside the cavity. These rich fuel mixtures are mixed with fresh air by the approachmixing layer at the front of the cavity and are thus involved in burning accompanied with the approach boundary layer separation extending towards upstream. The combustion flame in the downstream impinges onto the rear wall of the cavity and is then reflected back to the front of the cavity. During the recirculation of hot flow, heat is compensated for evaporation of droplets. The circulation processes mentioned above provide an efficient flame-holdingmechanism to stabilize the flame.Comparisons with results froma shorter length of cavity (cavity length of 45mm) show that, due to insufficient atomization and evaporation of the droplets in the short distance inside the cavity, parts of the droplets are carried out of the cavity through theboundary layer fluctuation and evaporated in the hot flame layer, thus resulting in incomplete air fuel mixing and worse combustion performance. The flow structures inside the cavity play an important role in the spray istribution, thus determining the combustion performance