Flexible nickel disulfide nanoparticles-anchored carbon nanofiber hybrid mat as a flexible binder-free cathode for solid-state asymmetric supercapacitors.

Nickel disulfide nanoparticles (NiS2NPs)-anchored carbon nanofibers (NiS2NPs@CNF) hybrid mats were fabricated via the sequential process of stabilization and carbonization of electrospun polyacrylonitrile-based fibers followed by hydrothermal growth of NiS2NPs on the porous surface of CNFs. The vertical growth of NiS2NPs on entire surfaces of porous CNFs appeared in the SEM images of hybrid mat. The hierarchical NiS2NPs@CNF core-shell hybrid nanofibers with 3D interconnected network architecture can endow continuous channels for easy and rapid ionic diffusion to access the electroactive NiS2NPs. The conductive and interconnected CNF core could facilitate electron transfer to the NiS2shell. Moreover, the porous CNF as a buffering matrix can resist volumetric deformation during the long-term charge-discharge process. The NiS2NPs@CNF electrode can yield high specific capacitance (916.3 F g-1at 0.5 A g-1) and reveal excellent cycling performances. The solid-state asymmetric supercapacitor (ASC) was fabricated with NiS2NPs@CNF mat as a binder-free positive electrode and activated carbon cloth as a negative electrode. As-assembled ASC not only produce high specific capacitance (364.8 F g-1at 0.5 A g-1) but also exhibit excellent cycling stability (∼92.8% after 5000 cycles). The ASC delivered a remarkably high energy density of 129.7 Wh kg-1at a power density of 610 W kg-1. These encouraging results could make this NiS2NPs@CNF hybrid mat a good choice of cathode material for the fabrication of flexible solid-state ASC for various flexible/wearable electronics.

Influence of composite insertion technique on gap formation.

AIM: To compare newer bulk-fill composites with an incrementally filled composite for adaptability and subsequent gap formation at the pulpal floor. MATERIALS AND METHODS: Class I cavities were prepared in 60 intact molars, with a shallow depression in the center of the pulpal floor. The samples were divided into four groups (n = 15), according to the material used; smart dentine replacement (SDR), SonicFill, Ever X Flow and Z350 XT, restored to a depth of 4 mm. Following thermocycling, samples were sectioned buccolingually and examined under a stereomicroscope. Seven samples from each group were coated with nail varnish except for approximately 1 mm around the tooth restoration junction. These samples were examined under stereomicroscope after staining with 2% buffered methylene blue dye. The remaining samples were examined under a scanning electron microscope for gap formation. The data were statistically analyzed using one-way ANOVA and post-hoc Bonferroni test. RESULTS: SDR showed the significantly best adaptability as compared to both SonicFill and Ever X Flow (comparable). However, significantly least adaptive capacity was seen in the incrementally filled group (Z350 XT). CONCLUSION: Bulk-fill composites performed better than incremental composites, demonstrating better adaptability and less gap formation at the pulpal floor.

Effect of QMix, peracetic acid and ethylenediaminetetraacetic acid on calcium loss and microhardness of root dentine.

OBJECTIVES: The objective of this in vitro study was to assess the effect of different chelating agents on the calcium loss and its subsequent effect on the microhardness of the root dentin. MATERIALS AND METHODS: Ten single rooted lower premolars were selected. The teeth were decoronated and thick transverse sections of 2 mm were obtained from the coronal third of the root. Each section was then divided into four quarters, each part constituting a sample specimen from the same tooth for each group. The treatment groups were: Group 1 (Control): 5% Sodium hypochlorite (NaOCl) for 5 min + distilled water for 5 min; Group 2: 5% NaOCl for 5 min + 17% ethylenediaminetetraacetic acid (EDTA) for 5 min; Group 3: 5% NaOCl for 5 min + 2.25% Peracetic acid (PAA) for 5 min and Group 4: 5% NaOCl for 5 min + QMix for 5 min respectively. The calcium loss of the samples was evaluated using the Atomic Absorption Spectrophotometer followed by determination of their microhardness using Vickers Hardness Tester. Data was analyzed using one-way ANOVA, Post hoc Tukey test and Pearson correlation. RESULTS: The maximum calcium loss and minimum microhardness was observed in Group 3 followed by Group 2, Group 4 and Group 1. There was a statistically significant difference between all the groups except between Groups 2 and 4. CONCLUSIONS: Irrigation with NaOCl + 2.25% PAA caused the maximum calcium loss from root dentin and reduced microhardness. A negative correlation existed between the calcium loss and reduction in the microhardness of root dentin.

Effect of accelerants on the immediate and the delayed sealing ability of mineral trioxide aggregate when used as an apical plug: An in vitro study.

AIM: To evaluate and compare the influence of various accelerators, 15% disodium hydrogen phosphate (Na2HPO4), 10% calcium chloride (CaCl2) and 23.1 wt% calcium lactate gluconate (CLG), on the immediate (after 72 h) and delayed (after 2 months) sealing ability of white ProRoot mineral trioxide aggregate (WMTA) when it is used as an apical plug. MATERIALS AND METHODS: Eighty, single-rooted mandibular premolars were instrumented and standardized artificial open apices were created. The samples were then randomly assigned into four experimental groups and two control groups. WMTA was mixed with the respective accelerators and an apical plug of 4-mm thickness was fabricated. The remaining canal spaces were then backfilled. The samples were stored for the stipulated time periods and then immersed in 0.2% Rhodamine B solution for 72 h. Dye leakage was analyzed using a stereomicroscope. RESULTS: Mean microleakage values of all experimental groups revealed that MTA + 23.1 wt% CLG showed the least leakage, followed by MTA + 15% Na2HPO4 and MTA + 10% CaCl2 with MTA + deionized water showing the maximum leakage at both the time intervals (P < 0.001). All the samples stored for a period of 2 months showed less leakage as compared with the samples stored for 72 h (P < 0.05). CONCLUSIONS: It was found that all three accelerators significantly accelerated the set of WMTA, of which 23.1 wt% CLG showed the best results, followed by 15% Na2HPO4 and 10% CaCl2. The sealing ability of all the experimental groups was significantly superior after 2 months as compared with that after 72 h.