VALIDATION OF "TARGIS" AND "VECTRIS" OSSICULAR PROSTHESES IN GUINEA PIG MODEL

The authors shared their results from the validation in a guinea pig model of a new ossicular prosthesis with Targis/Vectris System (Ivoclar, Lichtenstein). During the previous two years, the biocompatibility of teflon, gold, and ceramics was assessed. The biocompatibility of Targis and Vectris materials does not exist anymore as they are used in dental practice since 9 years. Targis is a ceramic optimized polymer of the family of ceromers. Vectris is a high-technology material replacing the metal substructure. These materials were inserted into a new medium, in the middle ear of a guinea pig. The experiments were carried out for different periods of time - 29 days, 70 days and 260 days. The ossicular prostheses were histologically examined. Targis and Vectris implanted retroauricularily into guinea pig' middle ear cavity did not show any inflammatory- reaction signs when contacting the skin of the external auditory channel. They proved to be well biologically tolerated even after 260 days after implantation

Simulated 3D Model of the Middle Ear for Theoretical and Practical Training for Students, Post-Graduate ENT Diseases Students and Beginning Otosurgeons

Post-graduate ENT diseases students and beginning otosurgeons go through a very important initial training period. The first steps in otosurgery are taken step by step. The transition from theoretical knowledge to temporal bone dissection courses is long and difficult. The lack of preliminary preparation vitiates and increases the cost of temporal bone dissection exercises.Simulated models bridge the gap between theory and practice and contribute to a more effective training.Aim: Developing a simulated 3D model of the mastoid process in real size and the part of the facial nerve passing through it; using a simulated 3D model of mastoid process for anatomical visualization of the hard to find and invisible structures of the middle ear and facial nerve and for nosological training.Material and methods:1. Cadaver temporal bone on which postauricular facial nerve decompression has been performed.2. Elaborating a silicone model based on a print taken from the operative cavity3. 3D printing of the models and colouring4. Putting electrical conductors and their connection to a tactile pointer and light indicatorsResults:The model:–– presents the hard to find and invisible microstructures of the middle ear and the part of the facial nerve passing through it–– allows work in two modes: anatomical and nosological–– contributes to more lasting preservation of knowledge, using the principle of active learning and training visual and tactile memory.Conclusion:The model is developed for tuition, precedes training models and can be improved. ---------------------------------------------------------------- Специализантите по УНГ болести и начинаещите отохирурзи преминават през много важен начален период на обучение. Първите стъпки в отохирургията се осъществяват step by step. Преходът от теоретични познания към курсовете по Temporal Bone Dissection е труден и продължителен. Липсата на предварителнаподготовка опорочава и оскъпява упражненията по дисекция на темпорална кост.Симулационните модели прехвърлят мост между теорията и практиката и допринасят за по-висока ефективност на обучението.Цел: Създаване на симулационен 3D модел в реални размери на processus mastoideus и частта на лицевия нерв, преминаваща през него; използване на симулационен 3D модел на processus mastoideus за анатомично онагледяване на трудно откриваемите и невидими структури на средното ухо и лицевия нерв и за нозологично обучение.Материал и методи:1. трупна темпорална кост, върху която е извършена Postauricular Facial Nerve decompression2. изработване на силиконов модел по взет отпечатък от оперативната кухина3. 3Д принтинг на моделите и оцветяване4. полагане на електрически проводници и свързването им към тактилна показалка и светлинни индикаториРезултати:Моделът:–– представя трудно откриваемите и невидими микроструктури на средното ухо и частта на лицевия нерв, преминаваща през него–– позволява работа в два режима: анатомичен и нозологичен–– допринася за по-трайно запазване на знанията, използвайки принципа на активното обучение и тренирането на зрителната и тактилната паметЗаключение:Моделът е създаден за обучение, предхожда моделите за тренинг и може да бъде усъвършенстван

Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1-20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two-dimensional and basin-scale three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. Furthermore, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial

Mechanistic insights into a hydrate contribution to the Paleocene-Eocene carbon cycle perturbation from coupled thermohydraulic simulations

During the Paleocene-Eocene Thermal Maximum (PETM), the carbon isotopic signature (δ13C) of surface carbon-bearing phases decreased abruptly by at least 2.5 to 3.0‰. This carbon isotope excursion (CIE) has been attributed to widespread methane hydrate dissociation in response to rapid ocean warming. We ran a thermohydraulic modeling code to simulate hydrate dissociation due to ocean warming for various PETM scenarios. Our results show that hydrate dissociation in response to such warming can be rapid but suggest that methane release to the ocean is modest and delayed by hundreds to thousands of years after the onset of dissociation, limiting the potential for positive feedback from emission-induced warming. In all of our simulations at least half of the dissociated hydrate methane remains beneath the seabed, suggesting that the pre-PETM hydrate inventory needed to account for all of the CIE is at least double that required for isotopic mass balance

Роля на 18F-FDG ПЕТ/КТ в диагностичния алгоритъм при злокачествените епителни тумори на глава и шия

Туморите на глава и шия са хетерогенна група с разнообразна локализация. Епителните тумори на глава и шия, от които 90% са с плоскоклетъчна хистология, имат сходно развитие, което определя еднотипния диагностичен подход при тях. Целта на настоящия обзор е да направи преглед на литературните данни, касаещи ролята на 18F-FDG ПЕТ/КТ в диагностичния алгоритъм при злокачествени тумори на глава и шия. Проучванията сочат, че целотелесният хибриден образен метод има важна роля при нодално и далечно стадиране, рестадиране, преценка за терапевтичен подход, оценка ефекта от лечение, ранна визуализация на рецидиви, скринингова детекция на синхронни/метахронни тумори и далечни метастази, дори без клинична изява. При пациенти с доказани метастатични шийни лимфни възли с плоскоклетъчна хистология FDG-ПЕТ/КТ помага за водене на насочена биопсия (панендоскопия) и откриване на първично туморно огнище. По-голям брой от пациентите са в напреднал стадий при установяване на заболяването. Точното стадиранe с целотелесно FDG-ПЕТ/КТ изследване, ранна визуализация на далечни метастази и втори първичен тумор при пациенти с епителни злокачествени тумори на глава и шия позволява своевременна промяна на терапевтичния подход, избор на индивидуален терапевтичен план и своевременно лечение според нуждите на пациента

Предимства и недостатъци на транспланти и имплантанти, използвани в уголемяващата ринопластика

Транспланти и импланти в ринохирургията се използват често, за да се реконструира поддържането структури за върха за нос, коригиране на седловиден нос, както и подобряване на функцията на носната клапа или форма на върха на носа. Уголемяващата ринопластика е била прилагана предимно при пациенти от жълтата раса, африканци или афроамериканци. Днес, с бързото развитие на пластичната и естетична хирургия, уголемяващата ринопластика е придобила голяма популярност в Азия. Целта на нашата статия е да представим световния опит по този проблем

Conflicting estimates of natural geologic methane emissions

Global bottom-up and top-down estimates of natural, geologic methane (CH4) emissions (average approximately 45 Tg yr–1) have recently been questioned by near-zero (approximately 1.6 Tg yr–1) estimates based on measurements of 14CH4 trapped in ice cores, which imply that current fossil fuel industries' CH4 emissions are underestimated by 25%–40%. As we show here, such a global near-zero geologic CH4 emission estimate is incompatible with multiple independent, bottom-up emission estimates from individual natural geologic seepage areas, each of which is of the order of 0.1–3 Tg yr–1. Further research is urgently needed to resolve the conundrum before rejecting either method or associated emission estimates in global CH4 accounting

Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?

There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane gas bubble dissolution using a combination of bubble modeling and acoustic observations of rising bubbles to determine what fraction of the methane transported by bubbles will reach the atmosphere. The bubble model predicts the evolving bubble size, gas composition, and rise distance and is suitable for almost all aquatic environments. The model was validated using methane and argon bubble dissolution measurements obtained from the literature for deep, oxic, saline water with excellent results. Methane bubbles from within the hydrate stability zone (typically below ∼500 m water depth in the ocean) are believed to form an outer hydrate rim. To explain the subsequent slow dissolution, a model calibration was performed using bubble dissolution data from the literature measured within the hydrate stability zone. The calibrated model explains the impressively tall flares (>1300 m) observed in the hydrate stability zone of the Black Sea. This study suggests that only a small amount of methane reaches the surface at active seep sites in the Black Sea, and this only from very shallow water areas (<100 m). Clearly, the Black Sea and the ocean are rather effective barriers against the transfer of bubble methane to the atmosphere, although substantial amounts of methane may reach the surface in shallow lakes and reservoirs

Geologic controls on gas hydrate occurrence in the Mount Elbert prospect, Alaska North Slope

This paper is not subject to U.S. copyright. The definitive version was published in Marine and Petroleum Geology 28 (2011): 589-607, doi:10.1016/j.marpetgeo.2009.12.004.Data acquired at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, drilled in the Milne Point area of the Alaska North Slope in February, 2007, indicates two zones of high gas hydrate saturation within the Eocene Sagavanirktok Formation. Gas hydrate is observed in two separate sand reservoirs (the D and C units), in the stratigraphically highest portions of those sands, and is not detected in non-sand lithologies. In the younger D unit, gas hydrate appears to fill much of the available reservoir space at the top of the unit. The degree of vertical fill with the D unit is closely related to the unit reservoir quality. A thick, low-permeability clay-dominated unit serves as an upper seal, whereas a subtle transition to more clay-rich, and interbedded sand, silt, and clay units is associated with the base of gas hydrate occurrence. In the underlying C unit, the reservoir is similarly capped by a clay-dominated section, with gas hydrate filling the relatively lower-quality sands at the top of the unit leaving an underlying thick section of high-reservoir quality sands devoid of gas hydrate. Evaluation of well log, core, and seismic data indicate that the gas hydrate occurs within complex combination stratigraphic/structural traps. Structural trapping is provided by a four-way fold closure augmented by a large western bounding fault. Lithologic variation is also a likely strong control on lateral extent of the reservoirs, particularly in the D unit accumulation, where gas hydrate appears to extend beyond the limits of the structural closure. Porous and permeable zones within the C unit sand are only partially charged due most likely to limited structural trapping in the reservoir lithofacies during the period of primary charging. The occurrence of the gas hydrate within the sands in the upper portions of both the C and D units and along the crest of the fold is consistent with an interpretation that these deposits are converted free gas accumulations formed prior to the imposition of gas hydrate stability conditions