Extrinsic electromagnetic chirality in all-photodesigned one-dimensional THz metamaterials

We suggest that all-photodesigned metamaterials, sub-wavelength custom patterns of photo-excited carriers on a semiconductor, can display an exotic extrinsic electromagnetic chirality in terahertz (THz) frequency range. We consider a photo-induced pattern exhibiting 1D geometrical chirality, i.e. its mirror image can not be superposed onto itself by translations without rotations and, in the long wavelength limit, we evaluate its bianisotropic response. The photo-induced extrinsic chirality turns out to be fully reconfigurable by recasting the optical illumination which supports the photo-excited carriers. The all-photodesigning technique represents a feasible, easy and powerful method for achieving effective matter functionalization and, combined with the chiral asymmetry, it could be the platform for a new generation of reconfigurable devices for THz wave polarization manipulation.Comment: 11 page

Terahertz optically tunable dielectric metamaterials without microfabrication

We theoretically investigate the terahertz dielectric response of a semiconductor slab hosting an infrared photoinduced grating. The periodic structure is due to the charge carries photo-excited by the interference of two tilted infrared plane waves so that the grating depth and period can be tuned by modifying the beam intensities and incidence angles, respectively. In the case where the grating period is much smaller than the terahertz wavelength, we numerically evaluate the ordinary and extraordinary component of the effective permittivity tensor by resorting to electromagnetic full-wave simulation coupled to the dynamics of charge carries excited by infrared radiation. We show that the photoinduced metamaterial optical response can be tailored by varying the grating and it ranges from birefringent to hyperbolic to anisotropic negative dielectric without resorting to microfabrication.Comment: 3 pages, 2 figure

Reconfigurable photoinduced metamaterials in the microwave regime

We investigate optically reconfigurable dielectric metamaterials at gigahertz frequencies. More precisely, we study the microwave response of a subwavelength grating optically imprinted into a semiconductor slab. In the homogenized regime, we analytically evaluate the ordinary and extraordinary component of the effective permittivity tensor by taking into account the photo-carrier dynamics described by the ambipolar diffusion equation. We analyze the impact of semiconductor parameters on the gigahertz metamaterial response which turns out to be highly reconfigurable by varying the photogenerated grating and which can show a marked anisotropic behavior.Comment: 6 figures, 7 page

Properties of a novel polydimethylsiloxane endodontic sealer

Abstract Aim: The study aims to assess sealing ability of a novel polydimethylsiloxane-based sealer in simulated wet root canals with wide apex, ion release (calcium and pH) and examine samples using ESEM. Materials and methods: GuttaFlow bioseal, GuttaFlow2, and RoekoSeal Automix (Coltène/Whaledent Inc.) were tested.Roots were prepared to obtain an apical diameter #40 using nickel-titanium rotary files (HyFlex CM, Coltène/Whaledent Inc.), each root was filled with single cone technique and immediately inserted into a simulated socket (filled with 0.02. mL of simulated body fluid) to reproduce the clinical conditions of a wet apical environment. Sealing ability was evaluated as fluid filtration rate at 1, 14, 28 days, and 10 months.After 28 days in simulated body fluid, apices were examined using an Environmental Scanning Electron Microscope (ESEM).Alkalinizing activity and calcium release was evaluated after 3. h and 1, 7, 14, and 28 days.Data were analysed using Kolmogorov-Smirnov test (p <. 0.05). Results: Fluid filtration analysis showed no significant difference within materials. Significant difference was observed between 10 months observation and other time frames (p <. 0.05) of the same group.GuttaFlow bioseal showed a significantly higher alkalinising activity (p <. 0.05). Calcium release ability showed no significant difference through time, however significant differences were observed among materials (p <. 0.05).Observation using ESEM at 28 days after root obturation showed the presence of the materials sealing the wide apical foramen. Conclusions: All materials showed satisfying sealing ability. However due to low calcium release, their use is not suggested when apical barrier formation and periapical bone regeneration are needed. © 2017 Società Italiana di Endodonzi

Evaluation of the root filling quality with experimental carrier-based obturators: a CLSM and FEG-SEM analysis

This study evaluated tubule penetration of GuttaFlow Bioseal with cold single cone or carrier-based technique, under confocal laser scanning microscopy (CLSM). Twenty straight single-rooted teeth were instrumented with Hyflex CM and divided in two groups (n = 10) according to the obturation method: single cold gutta-percha cones; experimental carrier-based obturators. GuttaFlow Bioseal, labelled with Rhodamine B dye, was used as sealer in both groups. Teeth transversally sectioned were observed under CLSM. Percentage of sealer penetration and integrity of sealer layer perimeter were measured. Surface and microstructural characteristics of obturators and gutta-percha cones were compared by FEG-SEM and EDX analysis. No significant differences were found between groups for each examined parameter. Significant differences (P &lt; 0.05) were reported mainly within groups. Integrity was similar among and within groups. FEG-SEM/EDX analysis of obturators revealed the presence of Ba and Zn. Carrier-based obturation technique associated with GuttaFlow Bioseal does not seem to affect sealer penetration into dentinal tubules

Emissions and energy consumption of a plug-in hybrid passenger car in Real Driving Emission (RDE) test

Abstract In the next years, the number of circulating plug-in hybrid electric vehicles was expected to increase worldwide. Hybrid electric/gasoline powertrain is considered a promising solution to meet the future goals of greenhouse gas emission reduction by road transport sector. This paper investigates the emissive and energetic behaviour of a plug-in hybrid electric passenger car over on road testing. Measurements of CO, CO2, NOx exhaust emissions and of main electric motor parameters were carried out by using portable emission measurement system over urban, rural and motorway routes in Naples (Italy). Routes were selected for complying with European Real Driving Emission (RDE) legislation. Moreover, an additional urban route, characterised by strong road grade and non-RDE compliant, was investigated. RDE test allowed to assess the influence of the battery state of charge, hybrid mode (charge sustaining and charge depleting), road grade and vehicle air conditioning on the exhaust emission and energy consumption. An overall advantage of charged battery and charge depleting mode was observed in terms of CO2 emissions and fuel consumption. CO and NOx emissions are strongly influenced by driving when the vehicle's internal combustion engine starts. When it occurs in motorway patterns, CO and NOx peak emissions are observed at tailpipe. Pure electric driving, with consequent zero emissions, are guaranteed over urban strong uphill when battery is full charged

Med Oral Patol Oral Cir Bucal

Abstract Objective: The purpose of the study was to evaluate the effect of water storage, adhesive system and root canal region on the hydrolytic degradation of dentin bonds to carbon fiber posts. Study design: Fiber posts were bonded to the root canals using different adhesive systems and composites: SB1 XT group (Scotchbond 1 XT/RelyX ARC), OBF group (One Up Bond F Plus/Ionotite F), and AB2 group (All Bond 2/C&amp;B) After water storage (10 days), all roots were sectioned into 1 mm beams and divided into coronal or apical group. The specimens were stored in water at 22-26 °C temperature for 15 or 60 days and tested for microtensile bond strength at a crosshead speed of 0.9 mm/min after the calculation of the bonding area. Statistical analysis was performed with ANOVA followed by Tukey test to detect differences between groups (α=0.05). SEM investigation was performed to determine the mode of fracture. Results: Bond strength at coronal and apical half showed significant differences between experimental groups both after 15 and 60 days of water storage. Premature failures were observed in 16-20% of specimens before storage in water. Conclusions: For the bonding systems tested, clinicians should consider that bond strength inside the root canal at apical half is lower than at coronal half irrespective of the adhesive system. The adhesion within the root canal is possible for SB1 XT and OBF groups unlike the AB2 group where adhesion to root canal dentine is not reliable. Nevertheless, apical half represents the worst scenario in which is possible to obtain a durable adhesion

Biomimetic Calcium-Silicate Cements Support Differentiation Of Human Orofacial Mesenchymal Stem Cells

Introduction Human orofacial bone mesenchymal stem cells (OFMSCs) from maxilla and mandible have robust osteogenic regenerative properties based on our previous reports that demonstrate phenotypic and functional differences between jaw and axial bone mesenchymal stem cells in same individuals. Furthermore, a combination of OFMSCs with bioactive calcium-releasing cements can potentially improve OFMSC multi-lineage differentiation capacity, but biocompatibility of calcium silicate cements with OFMSCs is still unclear. We tested the hypothesis that material extracts of calcium-releasing calcium-silicate cements support biomimetic microenvironment for survival and differentiation of human OFMSCs. Methods Two experimental calcium-silicate cements 1) calcium-silicate mineral powder (wTC) containing di- and tricalcium-silicate, calcium sulphate, and calcium chloride and 2) wTC doped with alpha-tricalcium phosphate (wTC-αTCP) were designed and prepared. Cement setting times were assessed by Gilmore needles, ability to release calcium and hydroxyl ions was assessed by potentiometric methods and OFMSC attachment to calcium-silicate discs was assessed. Calcium-silicate material extracts were tested for ability to support OFMSCs survival and in vitro/in vivo differentiation. Results Fewer OFMSCs attached to calcium-silicate discs relative to tissue culture plastic (p=0.001). Extracts of calcium-silicate cements sustained OFMSC survival, maintained steady state levels of vascular cell adhesion molecule-1, alkaline phosphatase and bone sialoprotein while upregulating their respective gene transcripts. Adipogenic and in vivo bone regenerative capacities of OFMSCs were also unaffected by calcium-silicate extracts. Conclusions Ion-releasing calcium-silicate cements support a biomimetic microenvironment conducive to survival and differentiation of OFMSCs. Combination of OFMSCs and calcium-silicate cement can potentially promote tissue regeneration in periapical bone defects

In Vitro Screening of the Apatite-Forming Ability, Biointeractivity and Physical Properties of a Tricalcium Silicate Material for Endodontics and Restorative Dentistry

Aim: Calcium silicate-based materials are hydraulic self-setting materials with physico-chemical properties suitable for endodontic surgery and good biological/clinical outcomes. The study aim was to evaluate the bio-properties (biointeractivity and apatite-forming ability) and selected physical properties (porosity, water sorption, solubility, and setting time) of Biodentine, a tricalcium silicate material for endodontics and restorative dentistry, compared to that of ProRoot MTA (Mineral Trioxide Aggregate) as gold standard material. Methods: Biodentine and ProRoot MTA pastes were prepared and analyzed for calcium release and alkalinizing activity (3 h–28 days), setting time, water sorption, porosity, solubility, surface microstructure and composition, and apatite-forming ability in simulated body fluid. Results: Biodentine showed higher calcium release, alkalinizing activity, and solubility but higher open and apparent porosity, water sorption, and a markedly shorter setting time. Calcium phosphate (CaP) deposits were noted on material surfaces after short ageing times. A CaP coating composed of spherulites was detected after 28 days. The thickness, continuity, and Ca/P ratio of the coating differed markedly between the materials. Biodentine showed a coating composed by denser but smaller spherulites, while ProRoot MTA showed large but less dense aggregates of spherulitic deposits. Conclusions: Biodentine showed a pronounced ability to release calcium and extended alkalinizing activity interlinked with its noticeable porosity, water sorption, and solubility: open porosities provide a broad wet biointeractive surface for the release of the calcium and hydroxyl ions involved in the formation of a CaP mineral. Biodentine is a biointeractive tricalcium silicate material with interesting chemical-physical properties and represents a fast-setting alternative to the conventional calcium silicate MTA-like cements