175 research outputs found
La fotógrafa Denise Bellon: surrealismo, documentalismo y fotografía humanista
No full textRESUMEN:Entre 1920 y 1940 se desarrolla en Francia un movimiento fotográfico denominado Nouvelle Vision que acoge a un grupo de fotógrafas profesionales de este medio, entre ellas Denise Bellon. Las imágenes de esta autora, estrechamente vinculadas con los artistas de vanguardia, nos servirán para articular conexiones con aspectos relacionados con tres corrientes fotográficas patentes en su trayectoria: el surrealismo, la fotografía humanista y el documentalismo. Para lograr este propósito nos aproximaremos, por un lado, a los rasgos específicos de cada una de estas tendencias fotográficas y por otro, a la obra de Denise Bellon a través del ensayo fílmico Le Souvenir d´un avenir (Recuerdos del porvenir, 2001) donde Yannick Bellon, su hija y el cineasta Chris Marker orquestan una narración cronológica, en la que la imagen fija adquiere status de protagonista absoluta basándose en 25000 negativos registrados entre 1937 y 1956.PALABRAS CLAVE:Fotografía, Denise Bellon, Chris Marker, surrealismo, documentalismo.ABSTRACT:A photographic movement known as Nouvelle Vision that includes a group of professional photographers of this medium, including Denise Bellon, takes place in France between 1920 and 1940. The images of this author, closely associated with the avant-garde artists, will serve us to articulate connections with three photographic trends patents in its career: surrealism, humanistic and documentary photography. To achieve this purpose us approximations, on the one hand, to the specific features of these photographic trends and on the other hand, to the work of Denise Bellon through the film essay Le Souvenir d´un l’avenir (Memories of the Future, 2001) where Yannick Bellon, his daughter and the filmmaker Chris Marker orchestrate a chronological narrative, in which the fixed image acquired status of absolute protagonist based on 25000 negatives between 1937 and 1956.KEYWORDS:Photography, Denise Bellon, Chris Marker, surrealism, documentary.</jats:p
La fotógrafa Denise Bellon: surrealismo, documentalismo y fotografía humanista
No full textA photographic movement known as Nouvelle Vision that includes a group of professional photographers of this medium, including Denise Bellon, takes place in France between 1920 and 1940. The images of this author, closely associated with the avant-garde artists, will serve us to articulate connections with three photographic trends patents in its career: surrealism, humanistic and documentary photography. To achieve this purpose us approximations, on the one hand, to the specific features of these photographic trends and on the other hand, to the work of Denise Bellon through the film essay Le Souvenir d´un l’avenir (Memories of the Future, 2001) where Yannick Bellon, his daughter and the filmmaker Chris Marker orchestrate a chronological narrative, in which the fixed image acquired status of absolute protagonist based on 25000 negatives between 1937 and 1956.Entre 1920 y 1940 se desarrolla en Francia un movimiento fotográfico denominado Nouvelle Vision que acoge a un grupo de fotógrafas profesionales de este medio, entre ellas Denise Bellon. Las imágenes de esta autora, estrechamente vinculadas con los artistas de vanguardia, nos servirán para articular conexiones con aspectos relacionados con tres corrientes fotográficas patentes en su trayectoria: el surrealismo, la fotografía humanista y el documentalismo. Para lograr este propósito nos aproximaremos, por un lado, a los rasgos específicos de cada una de estas tendencias fotográficas y por otro, a la obra de Denise Bellon a través del ensayo fílmico Le Souvenir d´un avenir (Recuerdos del porvenir, 2001) donde Yannick Bellon, su hija y el cineasta Chris Marker orquestan una narración cronológica, en la que la imagen fija adquiere status de protagonista absoluta basándose en 25000 negativos registrados entre 1937 y 1956
Cementum and enamel surface mimicry influences soft tissue cell behavior.
No full textAIMS
To test whether titanium surface roughness disparity might be used to specifically guide the behavior of gingiva fibroblasts and keratinocytes, thereby improving the quality of soft tissue (ST) integration around abutments.
METHODS
Titanium discs resembling the roughness of enamel (M) or cementum (MA) were created with normal or increased hydrophilicity and used as substrates for human fibroblasts and keratinocytes. Adhesion and proliferation assays were performed to assess cell-type specific responses upon encountering the different surfaces. Additionally, immunofluorescence and qPCR analyses were performed to study more in depth the behavior of fibroblasts and keratinocytes on MA and M surfaces, respectively.
RESULTS
While enamel-like M surfaces supported adhesion, growth and a normal differentiation potential of keratinocytes, cementum-emulating MA surfaces specifically impaired the growth of keratinocytes. Vice versa, MA surfaces sustained regular adhesion and proliferation of fibroblasts. Yet, a more intimate adhesion between fibroblasts and titanium was achieved by an increased hydrophilicity of MA surfaces, which was associated with an increased expression of elastin.
CONCLUSION
The optimal titanium implant abutment might be achieved by a bimodal roughness design, mimicking the roughness of enamel (M) and cementum with increased hydrophilicity (hMA), respectively. These surfaces can selectively elicit cell responses favoring proper ST barrier by impairing epithelial downgrowth and promoting firm adhesion of fibroblasts
Two- and three-piece implants to boost data generation in preclinical in vivo research-A short technical report.
No full textThe purpose of this technical report is to present two novel experimental implant designs to boost data generation in preclinical in vivo research. Specifically, the report describes the rationale and the components of (1) a two-piece experimental implant suitable for a small animal platform (e.g., the rabbit femur/tibial epiphysis model), consisting of a threaded apical- and a coronal cylindrical piece, which is intended for collecting two types of biomechanical data, and (2) a three-piece experimental implant suitable for a large animal platform (e.g., the mini-pig mandible model), consisting of an apical "wound chamber", which allows the collection of histological/histomorphometrical data, and a middle threaded and coronal cylindrical piece, which also allow the collection of two types of biomechanical data. The increased volume of information generated from a single experiment in a small animal platform, using the proposed two-piece implant design, may assist in a more qualified decision-making process, on whether it is relevant to proceed to further assessment using a large animal platform. Furthermore, the increased volume of information generated in a single animal experiment either in a small or large animal platform, using the proposed two- and three-piece implants, respectively, likely decreases the number of animals otherwise needed for collecting the same information with standard one-piece implants and, thus, contributes to the reduction/refinement elements of the 3R principle
Dislocation interactions with characteristic interfaces in Ag-Cu eutectic
No full textSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2016-07-07 without embargo termsThe student, Benjamin Eftink, accepted the attached license on 2016-02-19 at 08:50.The student, Benjamin Eftink, submitted this Dissertation for approval on 2016-02-19 at 08:53.This Dissertation was approved for publication on 2016-02-22 at 15:02.DSpace SAF Submission Ingestion Package generated from Vireo submission #9077 on 2016-07-07 at 13:27:24Made available in DSpace on 2016-07-07T19:52:53Z (GMT). No. of bitstreams: 4
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Previous issue date: 2016-02-2
Assessing the osseointegration potential of a strontium releasing nanostructured titanium oxide surface: A biomechanical study in the rabbit tibia plateau model.
No full textOBJECTIVES
To investigate the impact of a Ti-Sr-O technology, applied to either a turned surface or an SLA surface, on the mechanical robustness of osseointegration, benchmarked against the SLActive surface.
MATERIAL AND METHODS
Ti discs (6.25-mm-diameter and 2-mm-thick) with three different surfaces were inserted on the proximal-anterior part of the tibial plateau of adult Swedish loop rabbits: (I) turned surface modified with Ti-Sr-O (turned + Ti-Sr-O), (II) SLA surface modified with Ti-Sr-O (SLA + Ti-Sr-O), and (III) SLActive surface (SLActive). Following a healing period of 2 weeks and 4 weeks, the pull-out (PO) force needed to detach the discs from the bone was assessed, as a surrogate of osseointegration.
RESULTS
The SLActive surface exhibited statistically significant higher median PO forces, compared with the SLA + Ti-Sr-O surfaces at both 2- and 4 weeks post-op (p > .05). In this study, no single turned + Ti-Sr-O surface disk was integrated.
CONCLUSIONS
The tested Ti-Sr-O technology failed to enhance osseointegration; however, this finding may be related to the inappropriateness of the rabbit tibia plateau model for assessing third-generation implant surface technologies, due to the limited diffusion and clearance at the disk-bone interface
Greater Osseointegration Potential with Nanostructured Surfaces on TiZr : Accelerated vs. Real-Time Ageing
No full textSurface chemistry and nanotopography of dental implants can have a substantial impact on osseointegration. The aim of this investigation was to evaluate the effects of surface chemistry and nanotopography on the osseointegration of titanium-zirconium (TiZr; Roxolid®) discs, using a biomechanical pull-out model in rabbits. Two discs each were placed in both the right and left tibiae of 16 rabbits. Five groups of sandblasted acid etched (SLA) discs were tested: (1) hydrophobic without nanostructures (dry/micro) (n = 13); (2) hydrophobic with nanostructures, accelerated aged (dry/nano/AA) (n = 12); (3) hydrophilic without nanostructures (wet/micro) (n = 13); (4) hydrophilic with nanostructures, accelerated aged (wet/nano/AA; SLActive®) (n = 13); (5) hydrophilic with nanostructures, real-time aged (wet/nano/RTA). The animals were sacrificed after four weeks and the biomechanical pull-out force required to remove the discs was evaluated. Adjusted mean pull-out force was greatest for group wet/nano/RTA (64.5 ± 17.7 N) and lowest for group dry/micro (33.8 ± 10.7 N). Multivariate mixed model analysis showed that the pull-out force was significantly greater for all other disc types compared to the dry/micro group. Surface chemistry and topography both had a significant effect on pull-out force (p < 0.0001 for both), but the effect of the interaction between chemistry and topography was not significant (p = 0.1056). The introduction of nanostructures on the TiZr surface significantly increases osseointegration. The introduction of hydrophilicity to the TiZr implant surface significantly increases the capacity for osseointegration, irrespective of the presence or absence of nanotopography
Immediate loading of a fully tapered implant with deep apical threads placed in healed alveolar ridges vs. immediate extraction sockets
No full textOBJECTIVES
Immediate implant placement and loading is a practice that continues to gain traction in implant dentistry because it reduces treatment time and improves satisfaction. Novel implant designs that facilitate increased primary stability, while not compromising osseointegration and long-term survival are important to offer immediate solutions for missing teeth. Here, we hypothesize that fully tapered implants can obtain successful osseointegration with high survival rates after immediate loading in fresh extraction sockets and healed sites.
MATERIALS AND METHODS
13 swine with 73 implants were evaluated. Fully tapered or apically tapered implants were placed in extraction sockets and healed sites. Insertion torque and resonance frequency analysis were determined at placement and euthanasia. Animals were evaluated at: placement, and 1-week and 12-weeks after placement. Bone to Implant Contact (BIC), Bone Area / Total Area (BA/TA), and first BIC (fBIC) analyses was conducted.
RESULTS
The fully tapered implant achieved similar primary stability with lower insertion torque at placement (Fig. 2). Apically and fully tapered implants had comparable BIC (50.1% vs 59.4%) and ISQ (82.5 vs 80.3) values by 12 weeks in healed sites. In extraction sockets, BIC and ISQ for the apically tapered implant was 35.8% and 73.2 and 37.8% and 79.2 for the fully tapered implants, respectively (Fig. 2, 5).
CONCLUSIONS
In this short-term study, immediately loaded fully tapered implants obtained high survival with similar osseointegration ability as apically tapered implants when placed in healed sites and fresh extraction sockets. Fully tapered implants show promise for use in immediate loading and immediate placement
An in-situ synchrotron study of low positive and negative thermal expansion ceramics
No full textSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-12-04 without embargo termsThe student, Benjamin Hulbert, accepted the attached license on 2023-07-09 at 11:19.The student, Benjamin Hulbert, submitted this Dissertation for approval on 2023-07-09 at 11:41.This Dissertation was approved for publication on 2023-07-11 at 16:20.DSpace SAF Submission Ingestion Package generated from Vireo submission #19577 on 2023-12-04 at 17:01:07In this dissertation, three families of materials that exhibit low or negative thermal expansion were studied, including NaZr2(PO4)3-type materials, HfW2O8 and ZrW2O8, and rare-earth di-titanates. These materials were studied with high temperature, in-situ synchrotron and/or neutron diffraction to make thermal expansion measurements and determine structural, atomistic unit cell changes leading to the thermal expansion mechanism in each material. During the X-ray diffraction (XRD) experiments, a sample-to-detector distance correction was derived to analyze data more accurately. Samples were synthesized through a low temperature solution-based ceramic synthesis technique called the organic-inorganic steric entrapment method. In chapter 2, a specimen displacement correction method was derived for Debye-Scherrer powder XRD experiments with a flat area detector, which are common at synchrotrons. This correction does not require the use of an internal reference material, is applied during the Rietveld refinement step, and is analogous to the specimen displacement correction equations for Bragg-Brentano geometry experiments. The 2θ correction equation is compared to another specimen displacement correction based on the use of an internal reference material in which new integration and calibration parameters of area detector images are determined. In chapter 3, SrZr4P6O24, CaZr4P6O24, NaTi2P3O12, NaZr2P3O12, MgZr4P6O24, and related solid solutions were synthesized using the organic-inorganic steric entrapment method. The average linear thermal expansion of these materials was between -1 x10-6/℃ and 6 x10-6/℃ from 25 to 1500 ℃, extending the temperature ranges from previous studies by 300 to 700 ℃. High temperature polymorphs of CaZr4P6O24 and SrZr4P6O24 were solved by Fourier difference mapping and Rietveld refinement. This polymorph is present above 1262 and 1268 ℃, respectively. This work measured thermal expansion coefficients to 1500 ℃ for all samples and investigated the differences in thermal expansion mechanisms between polymorphs and between compositions. In chapter 4, the isotropic negative thermal expansion of ZrW2O8 and HfW2O8 was measured from 1105 to 1257 ℃ for ZrW2O8 and from 1105 to 1276 ℃ for HfW2O8. Their linear coefficients of thermal expansion were measured to be -5.52 x 10-6 ℃-1 and -4.87 x 10-6 ℃-1, respectively. This work presents the first in-situ, powder x-ray diffraction measurements of these materials at their thermodynamically stable temperature ranges. The thermal expansion mechanism of increased flexibility and transverse vibrations of the WO4 tetrahedra at temperatures below 775 ℃ appears consistent with the higher temperature region probed here. In chapter 5, the unit-cell parameter and the first temperature dependent coefficient of thermal expansion values for nine of the rare earth di-titanates from room temperature to approximately 1600 ℃, extending previous studies by 400 ℃ to 600 ℃. The monoclinic to orthorhombic transformation temperature in La2Ti2O7 was accurately determined with both in-situ, powder x-ray diffraction and neutron diffraction, giving a simpler approach to measuring this phase transformation at higher resolution than existing single crystal phase transformation studies
Primary stability and osseointegration comparing a novel tapered design tissue-level implant with a parallel design tissue-level implant. An experimental in vivo study.
No full textOBJECTIVES: The aim of the present study was to compare a novel tapered, double-threaded self-tapping tissue-Level design implant (TLC) to a well-established parallel walled tissue-level (TL) implant in terms of primary and secondary stability over time. MATERIALS AND METHODS: Test TLC (n = 10/per timepoint) and control TL (n = 10/per timepoint) implants were placed in the mandible of minipigs and left for submerged healing for 3, 6, and 12 weeks. Maximum insertion torque and implant stability quotient (ISQ) were measured for each implant at placement. Osseointegration and cortical bone maintenance were histologically evaluated by measuring total bone-to-implant contact (BIC) and first bone-to-implant contact (fBIC). RESULTS: A significantly higher maximum insertion torque was measured for the test implant TLC compared to the control TL implant (57.83 ± 24.73 Ncm and 22.62 ± 23.16 Ncm, respectively; p < .001). The mean ISQ values were comparable between the two implant types (75.00 ± 6.70 for TL compared to 75.40 ± 3.20 for TLC, p = .988). BIC was comparable between both implant types at each of the evaluated time points. The fBIC was found to be significantly more coronal at 12 weeks for the TLC implant compared to the TL implant (0.31 ± 0.83 mm for TLC compared to -0.22 ± 0.85 for TL, p = .027). CONCLUSION: The novel tapered tissue level design implant showed improved primary stability and an overall improved crestal bone height maintenance compared to the parallel walled design at 12 weeks
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