Controlling internal barrier in low loss BaTiO3 supercapacitors

Supercapacitor behavior has been reported in a number of oxides including reduced BaTiO3 ferroelectric ceramics. These so-called giant properties are however not easily controlled. We show here that the continuous coating of individual BaTiO3 grains by a silica shell in combination with spark plasma sintering is a way to process bulk composites having supercapacitor features with low dielectric losses and temperature stability. The silica shell acts both as an oxidation barrier during the processing and as a dielectric barrier in the final composite

Polaron relaxation in ferroelectric thin films

We report a dielectric relaxation in ferroelectric thin films of the ABO3 family. We have compared films of different compositions with several growth modes: sputtering (with and without magnetron) and sol-gel. The relaxation was observed at cryogenic temperature (T<100K) for frequencies from 100Hz up to 10MHz. This relaxation activation energy is always lower than 200meV. It is very similar to the polaron relaxation that we reported in the parent bulk perovskites. Being independent of the materials size, morphology and texture, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shapin

High-frequency dielectric spectroscopy of batio3 core - silica shell nanocomposites: Problem of interdiffusion

Three types of BaTiO3 core - amorphous nano-shell composite ceramics were processed from the same core-shell powder by standard sintering, spark-plasma sintering and two-step sintering techniques and characterized by XRD, HRSEM and broad-band dielectric spectroscopy in the frequency range 10^3 - 10^13 Hz including the THz and IR range. The samples differed by porosity and by the amount of interdiffusion from the cores to shells, in correlation with their increasing porosity. The dielectric spectra were also calculated using suitable models based on effective medium approximation. The measurements revealed a strong dielectric dispersion below the THz range, which cannot be explained by the modeling, and whose strength was in correlation with the degree of interdiffusion. We assigned it to an effect of the interdiffusion layers, giving rise to a strong interfacial polarization. It appears that the high-frequency dielectric spectroscopy is an extremely sensitive tool for detection of any gradient layers and sample inhomogeneities even in dielectric materials with negligible conductivity

Postoperative pain and surgical time comparison using piezoelectric or conventional implant site preparation systems

Since its introduction, piezoelectric bone surgery has established an important role in oral surgery and dental implantology. Piezoelectric surgery is efficient at preparing implant site osteotomies due to its selective cut, micro-streaming and cavitational effects, which preserve and maintain the soft tissue. Several advantages have been outlined in patient\u2019s symptoms, both in terms of improved intraoperative comfort and postoperative course. The aim of this study was to compare implant insertion procedures using piezoelectric surgery or conventional drilling. Intra- and postoperative pain, implant site preparation time and learning curve were evaluated. Methods: A total of 13 (7 women/6 men, aged between 45 and 75 years) partially edentulous patients were rehabilitated with 40 titanium implants (n=20). Implant therapy consisted in the inclusion of at least two conical implants between 3.8 and 4.5 mm diameter with a maximum torque of 35 Ncm in randomised bilateral edentulous areas. First sites were prepared with piezodevice (test sites) and the contralateral ones with conventional drilling (control sites). Surgery was always performed by the same operator. Implant site preparation timing was measured from flap elevation until implant inclusion. Patients recorded their subjective intraoperative and postoperative pain daily for 7 days and at 15th day after surgery using a Visual Analog Scale (VAS). Results: Patients treated with piezoelectric technique presented a lower VAS, minor swelling and less recovery time compared to the conventional technique. No operative complications were reported and the implant survival rate at 1 year was 100% for both the techniques. VAS significant differences were found for the test sites as intraoperative symptoms (p = 0.009), after 1 day (p = 0.010), 2 days (p = 0.016), 3 days (p = 0.017), 5 days (p = 0.015), 6 days (p = 0.018) and 7 days (p = 0.039). The average surgical times of implant sites preparation were: 10 (\ub1 1.4) minutes for the test sites, and 7.00 (\ub1 1.7) minutes for the control sites. In 69.2% of cases (9 of 13 patients) the operator has found advantages in terms of better access to the posterior sites, enhanced intraoperative visibility and insertion axis maintenance using the piezoelectric technique. The learning curve with piezodevice has seen a decrease in timing (rho = -0827, p = 0.001) from the first to the last intervention; whereas no significant difference was evaluated with the traditional method. Conclusion: Compared to traditional methods, piezoelectric technique enables optimal healing because it reduces the postsurgery swelling and discomfort. The average time necessary for the piezoelectric implant site osteotomy was approximately 3 minutes more than conventional technique

CROWN-TO-ROOT RATIO IN ENDODONTIC SURGERY: A SURVIVAL STUDY

Aim: to assess the influence of the crown height (CH), root length (RL) and crown-to-root ratio (CRR) on the survival of te- eth subjected to surgical endodontic retreatment and classi- fied as periapically healed. Methods: a single operator performed all the endodontic mi- crosurgery interventions. The present analysis selected the te- eth classified as ‘‘complete periapical healing’’ according to the Molven-Halse-Grung scale. The periapical radiographs were analyzed by two independent calibrated examiners, who measured CH and RL in a blind manner. The CRR was calcula- ted as the ratio of the two variables CH and RL. The measure- ments were performed by comparing the post-operative radio- graphs (t0) with those taken for a previous retrospective analysis (t1) and the most recent available (t2). An independent statistician conducted a survival analysis using Kaplan-Meier plots and a log-rank test (a = 0.05). Results: thirty-eight patients were evaluated, each one contri- buting to the study with a single tooth. The mean follow-up pe- riod was 5,96 ± 3,36 years. Comparing the CRR and RL values between t1 and t2, the difference was found statistically signifi- cant (p = 0.03). Survival was improved for the teeth with roots longer than 7 mm. There were no statistically significant diffe- rences among the remaining comparisons. Conclusions: root length ≥ 7mm exhibited better chances of long-term survival. Over time, a risk of further decrease of cli- nical RL due to periodontal disease and consequent increase of CRR could be critical by a mechanical point of view. Other studies are needed

A wire-loop technique for implantation of an iliac branched device in a patient with previous surgery for a ruptured abdominal aortic aneurysm

We described a modified technique for implanting a bridging stent-graft into an iliac branched device. A 79-year-old male who had received aortobiiliac synthetic graft surgery for a ruptured abdominal aortic aneurysm six months earlier was admitted to our unit for treatment of a left common iliac aneurysm involving the origin of the hypogastric artery. A standard technique was unsuccessful at implanting the bridging stent-graft, and therefore a wire-loop guidewire over the graft bifurcation was used to stabilize the contralateral sheaths and to complete the implantation. © Turkish Society of Radiology 2012

High quality MgB2 thin films in-situ grown by dc magnetron sputtering

Thin films of the recently discovered magnesium diboride (MgB2) intermetalic superconducting compound have been grown using a magnetron sputtering deposition technique followed by in-situ annealing at 830 C. High quality films were obtained on both sapphire and MgO substrates. The best films showed maximum Tc = 35 K (onset), a transition width of 0.5 K, a residual resistivity ratio up to 1.6, a low temperature critical current density Jc > 1 MA/cm2 and anisotropic critical field with gamma = 2.5 close to the values obtained for single crystals. The preparation technique can be easily scaled to produce large area in-situ films.Comment: 7 pages, 4 figure

Frontal brain asymmetries as effective parameters to assess the quality of audiovisual stimuli perception in adult and young cochlear implant users

How is music perceived by cochlear implant (CI) users? This question arises as "the next step" given the impressive performance obtained by these patients in language perception. Furthermore, how can music perception be evaluated beyond self-report rating, in order to obtain measurable data? To address this question, estimation of the frontal electroencephalographic (EEG) alpha activity imbalance, acquired through a 19-channel EEG cap, appears to be a suitable instrument to measure the approach/withdrawal (AW index) reaction to external stimuli. Specifically, a greater value of AW indicates an increased propensity to stimulus approach, and vice versa a lower one a tendency to withdraw from the stimulus. Additionally, due to prelingually and postlingually deafened pathology acquisition, children and adults, respectively, would probably differ in music perception. The aim of the present study was to investigate children and adult CI users, in unilateral (UCI) and bilateral (BCI) implantation conditions, during three experimental situations of music exposure (normal, distorted and mute). Additionally, a study of functional connectivity patterns within cerebral networks was performed to investigate functioning patterns in different experimental populations. As a general result, congruency among patterns between BCI patients and control (CTRL) subjects was seen, characterised by lowest values for the distorted condition (vs. normal and mute conditions) in the AW index and in the connectivity analysis. Additionally, the normal and distorted conditions were significantly different in CI and CTRL adults, and in CTRL children, but not in CI children. These results suggest a higher capacity of discrimination and approach motivation towards normal music in CTRL and BCI subjects, but not for UCI patients. Therefore, for perception of music CTRL and BCI participants appear more similar than UCI subjects, as estimated by measurable and not self-reported parameters

Fibrin clot adhesion to conditioned root surfaces: an in vitro study with scanning electron microscopy analysis

Aim: Periodontal regeneration is contingent on the adhesion and maturation of fibrin clot to a root surface exposed to periodontal disease. Root surface demineralization in vitro improves the formation of a stable union between the fibrin clot and the root surface. In scientific literature there are not studies of comparison that stand which demineralizing agent is the best in promoting fibrin clot adhesion. The aim of this study was to evaluate and compare the efficacy of six root conditionings in removing the smear layer and developing the fibrin clot in static and dynamic conditions. Methods: 36 single-root teeth extracted for periodontal disease were cut with a microtome in order to obtain 72 specimens that were divided in three groups: 24 samples not covered with blood, 24 covered with fresh human whole blood, 24 covered with blood and rinsed in a rotary shaker table (Vortex\uae). 4 specimens from each group were conditioned for 3 minutes with: physiological saline solution (FISIO) as the control group, saturated solution of citric acid 25% (AC), ethylenediaminetetraacetic acid 24% (EDTA), a solution of tetracycline 200mg/mL (TETRA), a solution of tetracycline and citric acid (TETRA+AC), Prefgel\uae and successively Emdogain\uae (EMD). Then the 48 samples from group 2 and 3 were covered with blood, which was allowed to coagulate for 20 minutes in a 37\ub0C chamber. The blocks were rinsed and dehydrated under standardized conditions; specimens of group 3 were vortexed (100rpm). All the blocks were then sputtered with gold and analyzed with SEM. SEM images were evaluated by two blinded examiners, starting from the cementoenamel junction (CEJ), at 5 standardized points 2 mm distant from each other. A statistical analysis was performed. Results: EMD samples showed a more disorganized smear layer, in which is probably present the residual vehicle (propylene glycol alginate). However, in the 90% of all the specimens smear layer was found. AC treated samples showed a firmly adherent fibrin clot that covered the surfaces for the 70% of the specimens (the data was statistically relevant). Same results were found in TETRA+AC samples. The conditioning with EDTA, TETRA and EMD resulted in a sparsely organized clot worsened by the application of tensile forces, especially in TETRA samples. Only few blood cells without any clot organization were found in the control group, confirming that conditioning root surfaces improves the fibrin clot adhesion. Conclusion: The best formation of fibrin clot was observed for AC treated samples; this is probably due to the increase of root surface wettability caused by AC. The other root conditioning agents, even if lead to results better than the control group, are more susceptible to external forces and do not promote a stable fibrin clot adhesion