91 research outputs found
Influence of Printing Angulation on the Flexural Strength of 3D Printed Resins: An In Vitro Study
No full textFeatured Application: Flexural strength is a fundamental parameter for long-lasting restorations. Printing angulation affects the flexural strength differently depending on the 3D printed material. This study compared the flexural strength of various 3D printed resins fabricated at different building angles (0°, 45°, and 90°). Four groups of resins were tested: Varseo Smile Teeth (Bego GmbH & Co., Bremen, Germany), V-print C&B Temp (Voco GmbH, Cuxhaven, Germany), Bego Triniq (Bego GmbH & Co. KG, Bremen, Germany), and Sprintray Crown (SprintRay, Los Angeles, CA, USA). A digital light processing 3D printer (Asiga MAX UV, NSW, Sydney, Australia) was used to fabricate the samples at the specified build angles (0°, 45°, and 90°) in accordance with the ISO 4049:2019 standard. Flexural strength was measured using a universal testing machine (Instron 5567; Instron Ltd., Norwood, MA, USA), and fracture analysis was performed using a scanning electron microscope (Jeol JSM-6060LV, Tokyo, Japan). Statistical analysis was carried out using the Statistical Package for the Social Sciences (SPSS, version 26; IBM Corp., Chicago, IL, USA). Means and standard deviations were calculated for each group, and statistical differences were assessed using one-way ANOVA followed by the Bonferroni post hoc test (p < 0.05). All tested resins exhibited high flexural strength values. The maximum flexural strength was observed in the 0° printed samples (137.18 ± 18.92 MPa), while the lowest values were recorded for the 90° printed samples (116.75 ± 24.74 MPa). For V-print C&B Temp, the flexural strength at 90° (116.97 ± 34.87 MPa) was significantly lower compared to the 0° (156.56 ± 25.58 MPa) and 45° (130.46 ± 12.33 MPa) orientations. In contrast, Bego Triniq samples printed at 45° (148.91 ± 21.23 MPa) demonstrated significantly higher flexural strength than those printed at 0° (113.37 ± 31.93 MPa) or 90° (100.96 ± 16.66 MPa). Overall, the results indicate that the printing angle has a significant impact on the flexural strength of the materials, with some resins showing lower strength values at the 90° build angle
Investigation of different types of titanium processing methods with regard to the influence of various preparatory treatments on the titanium porcelain compound bond strength
No full textGegenstand dieser Arbeit war die Untersuchung unterschiedlicher Titan-
Verarbeitungsverfahren und der Einfluss unterschiedlicher Vorbehandlungen auf
die Titan-Keramische Haftverbundfestigkeit. Als Verarbeitungsverfahren wurden
die Gießanlage „Rematitan autocast“, das „Biotan Gießgerät“, sowie das „BEGO
Medifakturing System“ und, die Gießanlage „Ticast Super R“ untersucht. Alle
Titanprüfkörper wurden mit der Titankeramik Triceram (Esprident) beschichtet.
Zur Prüfung kamen 196 Titanprüfkörper mit den Abmessungen 3 mm x 25 mm x 0,5
mm, die in vier Sätzen a 49 Prüfkörper aufgeteilt wurden. Jeder Satz wurde
dann in sieben Serien mit jeweils sieben Prüfkörpern aufgeteilt. Je eine Serie
wurden den unterschiedlichen Lagerungsbedingungen ausgesetzt. Die
Lagerungsbedingungen bestanden aus: 1.) Trockenlagerung 2.) Eine Woche
Nasslagerung 3.) Ein Monat Nasslagerung 4.) Sechs Monate Nasslagerung 5.) Eine
Woche Speichellagerung 6.) Ein Monat Speichellagerung 7.) Sechs Monate
Speichellagerung Nach Abschluß der Lagerung wurden die Abmessungen jedes
einzelnen Prüfkörpers erneut geprüft und die Verbundfestigkeitsprüfung mittels
des Dreipunktbiegeversuchs nach Schwickerath durchgeführt. Zum Einsatz kam
hierfür die Zwick Universal-Prüfmaschine. Bei der Auswertung der
Messergebnisse konnte festgestellt werden, dass die im Labor Lange mittels der
Gießanlage „Rematitan Autocast“ gefertigten Probekörper bei fast allen
Lagerungsarten die höchsten Haftverbundwerte lieferte. Lediglich bei der
einwöchigen Speichellagerung wurden diese Werte von den, bei der Firma BEGO
mittels des „BEGO Medifacturing Systems“ hergestellten Prüfkörpern
übertroffen. Das „BEGO Medifacturing System“ liegt zudem bei weiteren 4
Lagerungsarten nur wenig unter den von der „Rematitan Autocast“ gelieferten
Höchstwerten. Nur bei der einmonatigen Nasslagerung und der sechsmonatigen
Speichellagerung liefern die im Labor Ticost Brandenburg mittels der
Gießanlage „Ticast Super R“ gefertigten Prüfkörper günstigere Werte. Bei allen
7 Lagerungsarten weist der Haftverbund der im Labor 3B Dental mittels der
„Biotan Gießanlage“ gefertigten Prüfkörper die niedrigsten Messwerte auf. Die
vorliegende Untersuchung zeigt deutlich dass zukünftig den zur Gusstechnik
alternativen Titangerüst-Herstellungsverfahren größtes Augenmerk geschenkt
werden muss, besonders unter dem Hintergrund, dass die für diese Studie
verwendeten Prüfkörper im Jahr 2001 hergestellt wurden und somit zu den
ersten, mittels des „BEGO Medifakturing Systems“ gefertigten Titangerüste
zählen dürften. So scheint die Zukünftige Verbesserung der Haftverbundwerte
für Titan-Keramische Restaurationen nicht mehr in der Weiterentwicklung der
Titankeramischen Massen zu liegen, sondern in der Weiterentwicklung der
neuesten Titangerüst-Herstellungstechniken.Object of the present study was an investigation of different types of
titanium processing methods with regard to the influence of various
preparatory treatments on the titanium porcelain compound bond strength. The
different processing methods investigated were castings with the following
casting plants: “Rematitan autocast”, “Biotan casting plant”, “Ticast Super R”
as well as the “BEGO Medifacturing System”. All titanium test specimens were
veneered using the titanium porcelain Triceram (Esprident). A total number of
196 titanium test specimens with the dimensions of 25 mm x 3 mm x 0,5 mm,
which were distributed into four sets of 49 test specimens each. Each set was
the divident into esven series of the specimens each. One of each series was
then ages under the following different storage conditions: 1\. Dry
conditions. 2\. Wet conditions simulated by water for one week. 3\. Wet
conditions simulated by water for one month. 4\. Wet conditions simulated by
water for six months. 5\. Wet conditions simulated by artificial saliva for
one week. 6\. Wet conditions simulated by artificial saliva for one month. 7\.
Wet conditions simulated by artificial saliva for six months. After the aging
process in storage under the above named conditions the dimensions of all test
specimens were again measured and the bond strength was tested using the
Schwickerath crack-initiation test. A Zwick a universal testing machine was
used for this purpose. The evaluation of the measured bond strength values
yielded the highest results for those specimens manufactured using the
“Rematitan autocast” casting plant – almost irrespective of the type and
duration of storage. Solely for the condition of one week of wet storage
simulated with artificial saliva the bond strength values of test specimens
manufactured by BEGO company with the “BEGO Medifacturing System” surpassed
the values achieved by “Rematitan autocast” specimens. In a further four test
series the bond strength values achieved by the “BEGO Medifacturing System”
specimens were only a little below the maximal values achieved by the
“Rematitan autocast” specimens. In the remaining two wet condition storage
series ( one month wet storage simulated by water and six months wet storage
simulated by artificial saliva) the “Ticast Super R” specimens yielded
slightly higher bond strength values than BEGO. For all seven types of storage
the bond stength values yielded were lowest for test specimens manufactured in
a “Biotan casting plant”. The present study clearly shows that in future for
dental titanium frame manufacturing special attention will have to be paid to
methods differing from traditional casting methods. This refers to the fact
that BEGO does not use traditional casting in their “BEGO Medifacturing
System”, and the test specimens manufactured for this study in 2001 are among
the first test specimens ever manufactured with this system. At this point one
may venture to project that in future an optimization of bond strength values
for titanium-porcelain compounds are less to be expected from further
innovations and developments in porcelain material, instead more can be hoped
from innovations and developments of most recent manufacturing systems for
titanium frames
Le incisioni rupestri del Monte Bego nei diari di campagna di Clarence Bicknel. Ambiente fisico e presenza antropica
No full textBioelectrochemical production of graphene oxide using bacteria as biocatalysts
No full text2019 Summer.Includes bibliographical references.The demand for production of graphene oxide (GO), which is a precursor for large-scale production of graphene, has been increasing due to the broad array of uses of both nanomaterials. Due to the unique electrical and mechanical properties of these 2D nanomaterials, applications in composites have shown enhancements by contributing a tunable energetic band gap, high strength, and high transparency among other features. The tunable band gap of the graphene derivatives is one of the key properties of these nanomaterials. By varying the size of the energetic band gap (in eV) between the conduction and valence bands, resistance can be decreased to promote electron flow in the material lattice. A large energetic band gap (insulators) means more resistance for electron flow. Being able to control the band gap of a nanomaterial, allows for many applications in batteries, supercapacitors, and semiconductors being the most promising applications for these nanomaterials. Other applications include flexible electronics, renewable energy, drug delivery, contaminant removal, sensors, and more. Unfortunately, large-scale production of graphene using current methods is challenging due to low yield, impurities, high cost, high energy input, slow production rates and/or hazardous chemical reactants and wastes. For this study, the focus was on the bioelectrochemical production of GO (BEGO) as a novel technology for producing these nanomaterials with low energy input, inexpensive and non-hazardous reagents at standard conditions, and using microbes as biocatalysts. The BEGO process consists of a single-chamber microbial electrosynthesis cell (MES) that uses a graphite rod anode and a cathode (carbon cloth or stainless steel) to drive redox reactions. This MES can be operated at low voltage in a three-electrode (-0.8-1.4V vs. Ag/AgCl), or two-electrode system (~3.1V DC), with bacteria inoculated in a phosphate media solution. During this study, the BEGO process was investigated to advance understanding of the production process and the properties of the BEGO nanomaterial produced. To achieve this, the objectives established include: 1) developing methods for purifying and quantifying the nanomaterial during the production process in the complex aqueous-phase reactor matrix, 2) identifying key physical and chemical properties of the nanomaterial product using various spectroscopy and microscopy techniques, and 3) analyzing the microbial communities present in the reactors and in the graphite anode biofilm. To quantify the BEGO and estimate production rates, different spectrophotometric and gravimetric methods were used. Ultraviolet-visible spectroscopy (UV-Vis) at 229 nm was found to be the best method. This wavelength is specific to GO as it corresponds to the π → π * transitions of aromatic C-C bonds comprising the majority of the molecule, regardless of the oxidation state. Different centrifugation and filtration protocols were compared to purify the BEGO out of the complex matrix. For quantification methods in solution, centrifugation at 10,000 x g for 15 minutes was found to be the most effective method for removal of large particles and biological material, with BEGO remaining in solution. For material characterization, various techniques were used to identify the functional groups present and the morphology of the BEGO sheets. It was found through Fourier transform infrared spectroscopy (FT-IR) and UV-Vis, that the nanomaterial contained less carboxyl/carbonyl groups than GO produced by the traditional Hummers' method. Raman spectroscopy and thermogravimetric analysis (TGA) showed high disorder and weight loss events consistent with known GO spectra. Microscopy analysis revealed the BEGO process yields sheet sizes of a few hundred nm to 1-2 µm in lateral dimensions. Transparency and Fast Fourier transform (FFT) images indicate the BEGO consists of only single-layered to few-layered structures, which are needed for downstream applications. The microbial analysis was done on bioreactors with different inocula sources. DNA and RNA were extracted from both the bulk liquid media and the rod biofilm. At the end of the operation period, microbial communities in the bioreactors had diverged from the inoculum source. Microbial communities in the BEGO producing reactors consisted of both aerobic and anaerobic microorganisms. The most abundant genera on the rod biofilm were the unknown Comamonadaceae (10-11%), Hydrogenophaga (9-21%), Methyloversatilis (15-22%), and Pseudomonas (11-36%) all from the Proteobacteria phylum. Thus, these microbial phylotypes may play a key role in catalyzing BEGO production, enabling this novel and sustainable approach to nanomaterial synthesis
Experimental investigations for the qualitative and quantitative determination of the influence of different casting systems on the mechanical characteristics of dental alloys with a high gold content
No full textTitelblatt und Inhaltsverzeichnis
Einleitung
Schriftumsübersicht
Material und Methode
Ergebnisse
Diskussion
Zusammenfassung
Summary
Schriftumsverzeichnis
TabellenanhangBei der Entwicklung von Gusssystemen ist darauf zu achten, dass die
mechanischen und physikalischen Eigenschaften des Gussstückes den hohen
Ansprüchen in der Mundhöhle entsprechen. Das Ziel der vorliegenden Arbeit war
es, die mechanischen Kenngrößen auf den Einfluss verschiedener Gusssysteme hin
zu überprüfen. Dazu wurden je sechs Proben fünf verschiedener
Edelmetalllegierungen mit fünf verschiedenen Gusssystemen vergossen und die
mechanischen Eigenschaften mithilfe des Zugversuchs gemäß DIN EN 10002-1 und
der Härteprüfung nach Vickers ermittelt und verglichen. Des weiteren schloss
sich eine mikroskopische Untersuchung des Gefüges an. Untersucht wurden die
Schleudergusssysteme Fundor T, Fornax G und Fornax T sowie die Vakuum-
Druckgusssysteme Nautilus MC+ und Nautilus T der Firma BEGO. Die
hochgoldhaltigen Legierungen Bio PontoStar, PontoLloyd G, PontoLloyd L, Bio
PlatinLloyd und PlatinLloyd 100 der Firma BEGO fanden Verwendung. Die
Ergebnisse zeigen auf, dass die verwendeten unterschiedlichen Gusssysteme
keine klinisch relevanten Unterschiede bei der Härte oder den mechanischen
Parametern bewirken. Die mikroskopische Untersuchung zeigt eine Tendenz zum
Vorteil der Schleudergusssysteme an, mit denen in dieser Untersuchung
feinkörnigere Gefüge nachgewiesen werden konnten, als bei Legierungen, die mit
Vakuum-Druckgusssystemen vergossen wurden. Von den Legierungen kann hier den
platinmetallreichen Legierungen der Vorzug gegeben werden, da bei diesen ein
deutlich feinkörnigeres und homogeneres Gefüge nachgewiesen werden konnte. Das
Aufschmelzen der Legierungen mit der offenen Flamme des Gusssystems Fundor T
wirkte sich, im Vergleich zu dem Schmelzen mit den Hochfrequenzöfen der
anderen vier untersuchten Gusssysteme, nicht nachteilig auf die mechanischen
Eigenschaften und das Gefüge aus.With the development of casting systems it is to be made certain that the
mechanical and physical characteristics of the cast piece correspond to the
high requirements in the oral cavity. The aim of this present investigation
was to examine the mechanical characteristics in dependency of the influence
of different casting systems. Six samples off five different alloys were cast
and compared with five different casting systems. The mechanical
characteristics were determinated with the tensile test in accordance with DIN
EN 10002-1 and the hardness test by Vickers. A microscopic investigation of
the structure followed. The centrifugal casting systems Fundor T, Fornax G and
Fornax T as well as the vacuum pressure casting systems Nautilus MC+ and
Nautilus T of the company BEGO were examined. The alloys with a high gold
content Bio PontoStar, PontoLloyd G, PontoLloyd L, Bio PlatinLloyd and
PlatinLloyd 100 of the company BEGO were investigated. The results indicate
that the used different casting systems do not obtain significantly different
mechanical characteristics. The microscopic investigation indicates a tendency
for the advantage of the centrifugal casting systems. These casting systems
revealed in this investigation finer granular structures, than alloys, which
were casted with vacuum pressure casting systems. Preference can be given to
the platinum-metal-rich alloys, because for these a clearly finer granular and
homogeneous structure could be proven. Test specimens cast with an open flame
(Fundor T casting machine) revealed similar results as the other investigated
casting systems. All casting systems obtained with all alloys clinical
sufficient results
Mulheres em cursos de licenciatura em química: motivações e imagens sobre a profissão docente.
No full textEm um recorte de gênero, o presente trabalho buscou identificar as motivações para a docência de graduandas de cursos de Licenciatura em Química de uma universidade pública brasileira, bem como suas imagens sobre a profissão docente. Os resultados obtidos corroborama imagem de docência atribuída socialmente à profissão de professor, a qual é vista de maneira romantizada e missionária, aspectos estes que influenciam na identidade concebida à profissão e que favorece a desvalorização e descaracterização profissional. Defende-se quecabe aos cursos de formação inicial de professores superarem os paradigmas formativos que os envolvem, possibilitando aos licenciados a alteração das imagens profissionais por elesatribuídasao trabalho do professor
Les pierres gravées du Queyras : une petite image polygonale dont la forme rappelle la constellation d’Orion
No full textHistoire
Un jour de l’été 2001, de retour du col Blanchet (2897 m, au bout de la vallée de l’Aigue Blanche, commune de St. Véran 05350), je suivais un itinéraire hors du sentier.
À cette occasion, je fus frappé par une petite gravure étrange - dont la forme correspondait à peu près à celle d’une clepsydre - que j'avais observée juste en aval (vers l'ouest) du lac inférieur de Blanchet sur un des nombreux blocs polis par les glaciers et dispersés dans cette zone proche de la frontière.
Ce chaos de blocs a une origine toute locale: ils proviennent d’une nappe de marbre du Jurassique supérieur qui se trouve au pied de la Rocca Bianca (3059 m), pic qui domine la région des deux lacs Blanchet du côté français et la large cuvette de la Chenal (Chianale) du côté italien.
Ce jour-là, je considérai cette gravure, apparemment dépourvue d’intérêt, comme un simple amusement de quelque berger, voire un passe-temps réalisé à l’aide d’une baïonnette par quelque militaire de garde à la frontière franco-italienne.
Toutefois, après cette première observation, la lecture d’un article paru dans Valados Usitanos
n° 67, 2000 concernant la constellation d'Orion et sa mythologie en relation avec les plus anciennes traditions culturelles du contexte agro-pastoral des peuplades alpines, me poussa à reconsidérer cette pierre que j’avais entre-temps presque oubliée.
En 2003, la gravure fit donc l’objet d’un relevé photographique que je réalisai avec un appareil argentique.
J’envoyai ensuite les images, accompagnées d’un bref récit, à M. Piero Barale, l’auteur de l’article sur la constellation d’Orion mentionné ci-dessus.
À ma surprise, Barale jugea fort intéressant – il parlait de « Gravure exceptionnelle! » – le matériel envoyé, car cette gravure du Queyras lui semblait être presque la même qu’une autre originaire du mont Bego (Roche Z XIX. G III. R 35 alpha “ Anthropomorphe qui tient un arquée horizontale”).
Barale donna tout de suite un rapide aperçu de la gravure nouvellement découverte dans son livre, publié en 2004, sur la civilisation de la tribu des Ligures Bagienni (Gaule transalpine-Piémont), en reproduisant l’image en marge de la page 164, avec un bref aperçu.
Mon ami Renato Nisbet réussit à trouver une image de la gravure en forme de clepsydre du mont Bego (Fig. 1), dont le sens demeurait cependant plutôt obscur – disait-il – vu que les experts se bornaient à proposer quelque vague rapport avec les quatre traits horizontaux situés au-dessous.
Sur la base de la ressemblance étonnante, mais bien réelle, de la gravure du Queyras et de celle du mont Bego, répertoriée mais pas expliquée d’une façon exhaustive, il fut alors décidé de rédiger et publier en italien un bref rapport sur cette découverte et de fournir ainsi aux spécialistes de quoi alimenter leur réflexion ultérieure. (“....lasciando agli esperti del settore disciplinare ogni ulteriore speculazione").
Ce rapport est paru dans Valados Usitanos 81, 49-54, 2005.
Rapport technique (altitudes d’après la carte I.G.N. 3615)
La gravure se trouve isolée, en position excentrique, vers le bord N d’une large dalle plate de schiste marmoréen du Jurassique supérieur, bien polie par l’action glaciaire et inclinée vers le terrain en direction S–SO.
Sa forme ressemble à celle d’un trapèze irrégulier, dont le périmètre est: AB = 235 cm; BC = 55 cm; CD = 270 cm; DE = 200 cm; EF = 100 cm; FA = 150 cm (flèche sur la gravure) (Fig. 2).
Du site de la dalle, on voit en plongeant la tête de la vallée de l’Aigue Blanche, c’est-à-dire le large replat vallonné et gazonné dont la limite aval est la chapelle (flèche) de Notre-Dame de Clausis (commune de St. Véran, Queyras, Hautes-Alpes) (astérisque sur le refuge de la Blanche) (Fig. 3).
Sa position géographique est la suivante: environ 200 m au-dessus du lac de la Blanche à la cote de 2725 m, à peu près à la hauteur d’une ligne idéale tirée entre le lac de la Blanche (2499 m, refuge) et la partie aval du lac Blanchet inférieur (2746 m), environ 250 m (en ligne droite) du côté droit du sentier Clausis-col Blanchet-Chenal, 800 m de la frontière (en ligne droite): voir la carte géographique (Fig. 4), astérisque sur le site N 44°39’47.88”, E 6°56’47.87” (moyenne de 4 mesures GPS effectuées le 6/9/2012 à l’aide d’un appareil Bushnell BackTrack et légèrement corrigée selon Google Earth).
La gravure a été réalisée avec une série de petits trous coniques ou microcupules (environ 50) faits par la technique du trépan, dont la profondeur actuelle ne dépasse pas 1 cm.
Le contraste optique pour les photos de la gravure a été obtenu en saupoudrant la pierre avec de la terre foncée d’origine végétale (Fig. 5).
La longueur de la gravure est de 20 cm (22 cm si on compte aussi la cupule isolée en haut, à droite) (Fig. 6).
Autour de la gravure on trouve aussi trois microcupules isolées, une à quelques centimètres en dessous de la figure en forme de clepsydre et deux autres à quelque dix centimètres d’elle et vers le bord N de la dalle (Fig. 7, flèches).
On observe aussi deux microcupules à approximativement 1 m à l'est de la gravure et à la distance d’environ 11 cm l’une de l’autre (flèche sur la Fig. 8 ; Fig. 9).
L’axe de la gravure est orienté environ 25° en direction NO.
Le premier relevé photographique a été effectué le 1er septembre 2003 (images sur pellicule), un deuxième a été fait le 9 août 2008 (images numériques) et un troisième le 6 septembre 2012 (images numériques).
La position topographique de la dalle se voit bien sur la Fig. 2, où la pierre est photographiée d’amont en aval: la chaîne enneigée à l’horizon est le groupe Pelvoux-Barre des Écrins avec ses glaciers, le petit point blanc sur la crête du pic de Châteaurenard (2989 m) est l’observatoire astronomique du même nom (flèche), le pic ophiolitique noir et presque cylindrique à droite est le Rouchon (2929 m).
L’axe de la gravure est orienté à gauche du sommet situé à mi-chemin entre le pic de Châteaurenard et le Rouchon, c’est-à-dire le pic Traversier (2882 m), et il vise en bas la crête qui descend du pic de Châteaurenard.
Plus précisément, l’axe de la gravure est orienté vers le haut de la Mine de Cuivre, dont les sites d'exploitation s’étalent le long du couloir de Pinilière, et dont la partie haute (2450-2550 m) abrite les exploitations minières d’intérêt archéologique.
Sur la photo prise depuis les virages de la route qui monte à l’observatoire astronomique (Fig. 10), on voit très bien la position de la dalle (flèche blanche); au pied de la falaise on voit aussi le lac de la Blanche et le refuge (flèche noire); l’imposant pic noir est la Tête des Toillies (3175 m).
Voir aussi la photo de la Fig. 11, prise du bord du lac de la Blanche (flèche sur le site de la dalle).
Un peu au-dessous de la chapelle de N.-D. de Clausis se trouve l’ancienne mine de cuivre que nous avons citée, laquelle fut exploitée à l’époque romaine (trouvailles de pièces), mais était déjà bien connue et exploitée à l’Âge des Métaux1, vu qu’ici on trouvait - fait exceptionnel - du cuivre natif, qui ne demandait pas de traitement métallurgique particulier.
Aujourd’hui le cuivre natif est épuisé depuis très longtemps (on en retrouve encore cependant des traces), mais la mine a fonctionné jusqu’à la fin des années 1950 en exploitant de la bornite (un sulfure de fer et cuivre) de très bonne qualité.
À quelque cent mètres de la mine, on peut encore voir le site d’une carrière de beau marbre vert des Alpes (ophicalcite), cette carrière aussi est abandonnée depuis longtemps.
En conclusion, l’identification de cette gravure en forme de clepsydre avec la constellation d’Orion, de même que son probable rapport avec la Z XIX. G III. R 35 alpha du mont Bego, semble trouver la faveur des experts, alors que, en ce qui concerne l’époque à laquelle cet ensemble de microcupules pourrait remonter, nous ne pouvons rien affirmer.
On peut toutefois observer et aussi souligner que le cadre naturel de notre dalle a connu avec certitude une importante fréquentation humaine depuis la plus haute Antiquité.
NOTE
1Des campagnes de recherche archéologique menées vers la première moitié des années 1990 (A. Gattiglia, M. Rossi Les céramiques de la mine de cuivre préhistorique de Saint-Véran – Hautes Alpes, ANTROPOLOGIA ALPINA, 1994) ont permis de trouver les traces de l’exploitation de l’Âge du Bronze, c'est-à-dire plusieurs tessons de poterie, des tuyères en terre cuite pour souffler l’air dans le four à fusion, des scories de fusion avec un creuset fragmentaire, qui, selon des analyses effectuées par le C.N.R.S. - Université de Montpellier, se révéla être fait d’une pierre (serpentinite à flogopite) en provenance de la région piémontaise d'Ivrea, fournissant ainsi la preuve de relations de la mine avec la plaine du Piémont.
De récentes datations au radiocarbone témoignent que l’exploitation de la mine a dû commencer au moins vers l’an 2300 avant J-Ch. (D. Bourgarit, P. Rostan, E. Burger, L. Carozza, B. Mille, G. Artioli The beginning of copper mass production in western Alps: the Saint-Véran mining area reconsidered, HISTORICAL METALLURGY 42, 1-11, 2008)
Comparative study of the bond strength between different veneering ceramics on metal or ceramic frameworks in vitro on a front tooth crown by the VOSS test
No full textMit der vorgelegten Arbeit wurde das Ziel verfolgt, Untersuchungen zum
Haftverbund zwischen Verblendkeramiken auf Metall- und Keramikgerüsten zu
vergleichen. Die Materialprüfungen wurden in vitro mittels des VOSS-Versuchs
durchgeführt. Von den 130 untersuchten Prüfkörpern wurden 11 Testreihen auf
Basis eines Metallgerüstes im Press-on Verfahren keramisch verblendet. Bis auf
die von BEGO Medical im SLM-Verfahren gefertigten 6 Gerüste der Charge auf
Basis der Legierung Wirobond® C+, wurden die übrigen 10 Versuchschargen á 7
Metallgerüste eigenhändig im Gussverfahren hergestellt. Insgesamt wurden davon
sechs Testreihen mit EMF-Legierungen (Wirobond® 280, Wirobond® C, Wirobond®
SG, Wirobond® C+, Wiron® 99, Wirocer plus) gefertigt und fünf Testreihen mit
EM-Legierungen (BegoPal 300, BegoCer G, Bio Pontostar, Bio Pontostar XL,
PontoLloyd P) hergestellt. Verblendet wurden alle metallischen
Gerüstmaterialien mit der Presskeramik BeCePress von Bego. 47 der 130
untersuchten Prüfkörper sind den Vollkeramikkronen zuzuordnen. Dabei wurden 47
Kronen in 7 Testreihen unterteilt. Bis auf die Versuchschargen von Inceram
Alumina / Vitadur und IPS e-max Press, bei denen nur sechs Prüfkörper
gefertigt wurden, bestanden die verbliebenen fünf Testreihen aus jeweils 7
Prüfkörpern. Die Fertigung der 7 vollkeramischen Systeme variieren in
Abhängigkeit der ent¬sprechenden Herstellungsprozesse. Zum einen wurden
keramische Gerüst¬materialien (Inceram Alumina, Zirkon) manuell keramisch
verblendet (Vitadur). Zum anderen wurden Vollkeramiksysteme aus einem Material
gefertigt (Empress). Einen Sonderstatus nehmen die Galvanokronen ein. Bei
diesen Kronen orientiert sich der keramische Werkstoff an einer hauchdünnen
Goldschicht. Die Testmethode nach Voss erlaubt universelle
Einsatzmöglichkeiten und praxisnahe Untersuchungen. Aber aufgrund einer
fehlenden Normierung und stark schwankenden Messwerten ist dieses
Prüfverfahren kritisch zu betrachten. Dennoch ermöglicht diese Materialprüfung
einen einzigartigen Vergleich zwischen verschiedenen Verbundsystemen. Die
Ergebnisse des VOSS-Tests weisen darauf hin, dass der überwiegende Anteil der
geprüften Frontzahnkronen klinischen Ansprüchen genügt. Lediglich vereinzelte
Messwerte bei vollkeramischen Systemen lassen ein Versagen der prothetischen
Versorgung bei maximaler Kaukraftbelastung im Frontzahnbereich vermuten.
Obwohl der VOSS-Test die klinische Tauglichkeit vollkeramischer Kronen bzw.
Galvanokronen bei einem gewählten Grenzwert von 400 N bestätigt, können
außergewöhnliche Belastungssituationen (z. B. Bruxismus) die Stabilität des
Haft¬verbunds gefährden. Einzig Vollkeramiksysteme auf Basis von
Zirkoniumdioxid konnten in dieser Studie solchen Kräften standhalten. Die
untersuchten Metall-Keramik-Systeme überzeugen im Vergleich zu den
Vollkeramiken mit höheren Messwerten. Die Verwendung von Press-on-Keramiken
als Verblendmaterial der Metallgerüste verdeutlicht die Praxistauglichkeit
dieses Werkstoffs. Zusammenfassend konnten die Untersuchungen des Voss-Tests
zeigen, dass aufgrund der Bruchfestigkeiten vollkeramische Lösungen im
Frontzahnbereich eine Alternative zu Metall-Keramik-Verbundsystemen sind.The aim of this study was to compare and to analyse the bond strength of metal
ceramic systems and full ceramic systems by using the testing method purposed
by VOSS against the background of clinical suitability. The 130 specimens were
designed as prosthetic anterior crowns of the human maxilla. 83 of the 130
dental crowns belong to the group of metal-ceramic systems.This 83 specimens
were divided into 11 test series based on a metal framework. Except for the 6
frames of the lot based on the alloy Wirobond ® C + manufactured by BEGO
Medical in SLM process, all the remaining 10 experimental batches were
prepared in a 7 frames, metal hand in the casting process. The metal
frameworks were made out of non-precious alloys (Wirobond ® 280, Wirobond ® C,
Wirobond ® SG, Wirobond ® C +, Wiron ® 99, Wirocer plus) and precious metal
alloys (BegoPal 300, BegoCer G, Bio PontoStar prepared Bio PontoStar XL,
PontoLloyd P). All metallic framework materials were veneered with the press
on ceramic BeCePress of BEGO. 47 of the 130 examined specimens are classified
as all-ceramic crowns. The 47 crowns were divided into 7 test series. Up to
the experimental batches of Inceram Alumina / Vitadur and IPS e-max press in
which only six test pieces were produced, all the remaining five tests
included in each case 7 specimens. The 7 full ceramic crowns are produced in
different manufacturing processes. Ceramic framework materials like Zirkonia
were manually veneered. Other full ceramic materials like Empress were made
out of one material. Galvano crowns take a special place in the full ceramic
system. These crowns are made of ceramic material based on a very thin layer
of gold. The test method to Voss allows universal application and practical
investigations. But due to lack of standardization and fluctuating readings of
this test method is to be criticized. Nevertheless, this material provides a
unique comparison test between different composite systems. The results of the
VOSS-testing indicate that the majority of the tested anterior crowns meet
clinical requirements. Only isolated measurements for all-ceramic systems have
a failure of the restoration at maximum masticatory suspect in the anterior
region. Although the VOSS test the clinical utility and galvano-ceramic crowns
with a set limit of 400 N confirmed to particular pressures situations (such
as bruxism) destabilize the compound. Only all-ceramic systems based on
zirconium dioxide in this study were able to withstand such forces. The
investigated metal-ceramic systems are impressive in comparison to the all-
ceramic materials with higher readings. The use of press-on ceramics as a
veneering of metal frameworks illustrates the feasibility of this material. In
summary, the VOSS-test studies show that all-ceramic solutions in the anterior
region are an alternative to metal-ceramic systems
Validation by Measurements of a IC Modeling Approach for SiP Applications
No full textThe growing importance of signal integrity (SI) analysis in integrated circuits (ICs), revealed by modern systemin-package methods, is demanding for new models for the IC sub-systems which are both accurate, efficient and extractable by simple measurement procedures. This paper presents the contribution for the establishment of an integrated IC modeling approach whose performance is assessed by direct comparison with the signals measured in laboratory of two distinct memory IC devices. Based on the identification of the main blocks of a typical IC device, the modeling approach consists of a network of system-level sub-models, some of which with already demonstrated accuracy, which simulated the IC interfacing behavior. Emphasis is given to the procedures that were developed to validate by means of laboratory measurements (and not by comparison with circuit-level simulations) the model performance, which is a novel and important aspect that should be considered in the design of IC models that are useful for SI analysi
Study of the intra-arterial distribution of Fe3O4 nanoparticles in a model of colorectal neoplasm induced in rat liver by MRI and spectrometry
No full textJos&eacute; J Echevarria-Uraga,1 Ignacio Garc&iacute;a-Alonso,2 Fernando Plazaola,3 Maite Insausti,3 N&eacute;stor Etxebarria,3 Alberto Saiz-L&oacute;pez,4 Bego&ntilde;a Fern&aacute;ndez-Ruanova51Radiology Department, Hospital de Galdakao-Us&aacute;nsolo, Bizkaia, Spain; 2Experimental Surgery Laboratory, Medicine Faculty, University of the Basque Country, Bizkaia, Spain; 3Faculty of Science and Technology, University of the Basque Country, Bizkaia, Spain; 4Pathology Department, Hospital de Galdakao-Us&aacute;nsolo, Bizkaia, Spain; 5Osatek SA Unidad del Hospital de Galdakao-Us&aacute;nsolo, Bizkaia, SpainPurpose: To evaluate, in an experimental model, the reliability of MRI for determining whether a higher iron concentration was obtained in tumor tissue than in normal liver parenchyma after intra-arterial administration of Fe3O4 lipophilic nanoparticles.Materials and methods: WAG/RijCrl rats were inoculated in the left hepatic lobe with 25,000 syngeneic CC-531 colon adenocarcinoma cells, after which they were randomized into two groups: control (CG) and infused (IG). After confirming tumor induction, the IG rats received intra-arterial suspensions of Fe3O4 nanoparticles (2.6 mg) in Lipiodol&reg; (0.15 mL). To calculate the iron concentration, [Fe], in the tumor and liver tissues of both groups of rats, measurements of signal intensity from the tumors, healthy liver tissue, and paravertebral muscles were made on a 1.5T MRI system in gradient-echo DP* and T2*-weighted sequences. In addition, samples were collected to quantify the [Fe] by inductively coupled plasma-mass spectrometry (ICP-MS), as well as for histological analysis. Statistical analysis was performed with non-parametric tests, and Bland&ndash;Altman plots were produced; P values &lt;0.05 were considered significant.Results: In the CG rats (n = 23), the mean [Fe] values estimated by MRI and ICP-MS were 13.2 &micro;mol &bull; g-1 and 5.9 &micro;mol &bull; g-1, respectively, in the tumors, and 19.0 &micro;mol &bull; g-1 and 11.7 &micro;mol &bull; g-1, respectively, in the hepatic tissue. In the IG rats (n = 19), the values obtained by MRI and ICP-MS were 148.9 &micro;mol &bull; g-1 and 9.4 &micro;mol &bull; g-1, respectively, in the tumors, and 115.3 &micro;mol &bull; g-1 and 11.6 &micro;mol &bull; g-1, respectively, in the healthy liver tissue. The IG results revealed a clear disagreement between MRI and ICP-MS. In the comparative analysis between the groups regarding the [Fe] values obtained by ICP-MS, significant differences were found for the tumor samples (P &lt; 0.001), but not for the hepatic tissue (P = 0.92). Under microscopy, scattered intravascular deposits of nanoparticles were observed, especially in the tumors.Conclusion: ICP-MS demonstrated significant uptake of exogenous iron in tumor tissue. MRI was useful for quantifying the [Fe] in the different tissues in the CG animals, but not in the IG animals. Although the irregular distribution of nanoparticles caused an important bias in the measurements obtained by MRI, the relative increase in iron content inside the tumor was suggested.Keywords: liver neoplasm, hepatic arterial infusion, ferromagnetic particle, iron concentration, MRI, spectrometry&nbsp
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