ABSTRACT
Esthetic implant therapy can be challenging in the anterior maxilla, and meticulous treatment is often required to deliver optimal esthetics. Close collaboration between surgical and prosthetic team members using the novel approach of prosthetic crown lengthening helped camouflage a shallow implant platform location, providing the proper gingival frame for esthetic restorations. This case report presents an interdisciplinary approach that included ridge augmentation, second-stage crown lengthening, and prosthetic soft tissue manipulation to address an implant placed too shallow in the alveolus of an extraction socket.
Subject(s)
Alveolar Ridge Augmentation/methods , Dental Implantation, Endosseous/methods , Dental Implants, Single-Tooth , Esthetics, Dental , Immediate Dental Implant Loading/methods , Tooth Socket/surgery , Alveolar Process/surgery , Bone Transplantation , Crown Lengthening , Dental Abutments , Dental Prosthesis Design , Female , Gingiva/surgery , Gingivectomy , Heterografts/transplantation , Humans , Incisor/surgery , Maxilla/surgery , Middle Aged , Radiography, Dental, Digital , Tooth Extraction , Treatment Outcome , ZirconiumABSTRACT
Metamaterial absorbers have been demonstrated across much of the electromagnetic spectrum and exhibit both broad and narrow-band absorption for normally incident radiation. Absorption diminishes for increasing angles of incidence and transverse electric polarization falls off much more rapidly than transverse magnetic. We unambiguously demonstrate that broad-angle TM behavior cannot be associated with periodicity, but rather is due to coupling with a surface electromagnetic mode that is both supported by, and well described via the effective optical constants of the metamaterial where we achieve a resonant wavelength that is 19.1 times larger than the unit cell. Experimental results are supported by simulations and we highlight the potential to modify the angular response of absorbers by tailoring the surface wave.
ABSTRACT
We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a single unit cell in the propagation direction, thus achieving an absorption coefficient alpha = 2000 cm(-1). These metamaterials are promising candidates as absorbing elements for thermally based THz imaging, due to their relatively low volume, low density, and narrow band response.
Subject(s)
Electrochemistry/methods , Algorithms , Computer Simulation , Equipment Design , Magnetics , Materials Testing , Microwaves , Models, Statistical , Models, Theoretical , Permeability , Photons , Refractometry/methodsABSTRACT
We present novel metamaterial structures based upon various planar wallpaper groups, in both hexagonal and square unit cells. An investigation of metamaterials consisting of one, two, and three unique sub-lattices with resonant frequencies in the terahertz (THz) was performed. We describe the theory, perform simulations, and conduct experiments to characterize these multiple element metamaterials. A method for using these new structures as a means for bio/chemical hazard detection, as well as electromagnetic signature control is proposed.
Subject(s)
Manufactured Materials , Models, Chemical , Computer Simulation , Materials Testing , Scattering, Radiation , Terahertz RadiationABSTRACT
PURPOSE: The extensive and unpredictable biliary excretion of CPT-11 and its metabolites, SN-38 and SN-38 glucuronide (SN-38G) may contribute to the wide interpatient variability reported in the disposition and gastrointestinal toxicity of CPT-11. We studied the role of P-glycoprotein (P-gp) in in vivo biliary excretion of CPT-11, SN-38 and SN-38G in mice lacking mdr1-type P-gp [ mdr1a/1b(-/-)] in the presence of the multidrug resistance (MDR) reversal agent, PSC833. METHODS: Wild-type (Wt) and mdr1a/1b(-/-) mice ( n=3 or 4) were treated intragastrically with PSC833 (50 mg/kg) or vehicle 2 h prior to i.v. CPT-11 dosing (10 mg/kg), and bile samples were collected. RESULTS AND CONCLUSIONS: P-gp was found to play an important role in CPT-11 biliary excretion, as there was a significant (40%, P<0.05) decrease in its biliary recovery in 90 min in mdr1a/1b(-/-) mice (6.6+/-0.6% dose) compared with Wt mice (11+/-1.2%). This also implied a major role of other undetermined non-P-gp-mediated mechanism(s) for hepatic transport of CPT-11, which was inhibited by PSC833 (1.8+/-0.8% with PSC833, 6.6+/-0.6% without PSC833) in mdr1a/1b(-/-) mice. SN-38 and SN-38G biliary transport was unchanged in mice lacking P-gp after vehicle treatment, indicating a lack of P-gp mediation in their transport. PSC833 significantly reduced (56-89%) SN-38 and SN-38G biliary transport in Wt and mdr1a/1b(-/-) mice, suggesting that PSC833 may be a candidate to modulate biliary excretion of SN-38 with potential use in reducing CPT-11 toxicity.
