Search Results (16)

Background and Objectives: Nickel–titanium (Niti) instruments have enhanced root canal cleaning in primary teeth, but file fractures are still common. Materials and Methods: This study evaluated the cyclic fatigue resistance of 120 Niti files from four different systems, A: Kedo SG (n = 30); B: Neoendo Pedoflex (n = 30); C: Pedoflex Waldent files (n = 30); and D: Vortex Blue files (n = 30). All the files had similar tip diameters (0.25 mm) and tapers (0.4%) and underwent heat treatment during manufacturing. Cyclic fatigue tests showed notable variations in cycles to fracture (NCF) across groups. All fracture surfaces of the files were assessed through scanning electron microscopy. Results: The mean values achieved in the experimental groups (A, B, C) were less than those in the control Group D (976.90 ± 1085.19). Files in Group A demonstrated the highest NCF (697.01 ± 420.09), while Pedoflex files in Group C showed the lowest values (203.88 ± 155.46). Statistical analysis using the Mann–Whitney test revealed significant differences between Group C and Groups A, B, and D and no differences among Groups A, B, and D. Conclusions: These findings suggest that Kedo SG and Neoendo Pedoflex files offer comparable cyclic fatigue resistance to Vortex Blue files. In contrast, Pedoflex Waldent files exhibit lower resistance to fracture. Full article

Recently, the single-cone hydraulic canal filling technique using bioceramic sealers was found to hinder retreatment due to the mechanical properties of the bioceramic sealers. This study assessed the effectiveness of four nickel–titanium rotary files in removing gutta-percha and bioceramic sealer from molar root canals in vitro. Eighty-eight root canals from extracted molars were instrumented with Vortex Blue rotary files and filled with gutta-percha and bioceramic sealer using a single-cone technique. After 30 days, the filled canals were randomly divided into four groups according to the file used for re-instrumentation: ProTaper Gold (PTG), Endo ReStart (ERS), XP-3D Shaper (XPD), and HyFlex Remover (HFR). This study assessed whether root canal filling material removal and patency were achieved within a 10-min time frame, recording the time required in seconds. The rate of regaining patency and the time required to achieve patency were compared among groups using a generalized linear model. Scanning electron microscopy was used to evaluate the mechanical changes to the files after use. The patency rate of XPD and HFR was significantly higher than PTG. ERS and XPD demonstrated shorter patency times than HFR and significantly shorter patency times than PTG. SEM images revealed a varied range of reverse windings across file groups. PTG and ERS exhibited microcracks and fractured tips, while XPD and HFR did not display these mechanical alterations. The four file systems in this study displayed varying levels of effectiveness in the retreatment of root canals filled with bioceramic sealers. Full article

This study aimed to assess and evaluate the canal shaping ability of two different Ni-Ti rotary systems, Vortex Blue (VB) and TruNatomy (TN), using micro-computed tomography in extracted premolars. A total of 20 extracted bifurcated maxillary first premolars with two separate canals were randomly divided into two groups and prepared with either VB 35/0.04 (Dentsply Maillefer, Ballaigues, Switzerland) or TN Medium 36/0.03 (Dentsply Sirona). Pre- and post-instrumentation micro-CT scans were analyzed to measure the following parameters: percentage of untouched canal surface area, changes in canal surface area, changes in canal volume, structural model index (SMI), changes in canal angulation, changes in dentin thickness, transportation, and centering ability. Statistical analysis was performed with a significance level set at p-value < 0.05. Both VB and TN files showed a significant increase in the basic canal geometry parameters including canal surface area and canal volume. Both file systems showed no significant changes in SMI or dentin thickness after canal instrumentation (p > 0.05). Some degree of canal transportation and a similar centering ability ratio with no significant difference were observed in both file systems (p > 0.05). TN files showed less pre-cervical dentin removal when compared to VB files. A significant difference was found in the TN group regarding the dentin removal between coronal and apical thirds (p = 0.03). Both VB and TN files produced comparable root canal preparation with no considerable shaping mishaps and errors. Both files showed minimum canal transportation and minimum straightening of the canal curvature. TN files removed less pre-cervical dentin than apical dentin. Full article

In this study, we present a method for ion-associated liquid phase (IALP) separation and concentration of analytes from an aqueous matrix into an IALP formed in situ by the charge neutralization reaction of organic cations and anions, without centrifugation. The effects of various factors on the extraction efficiency and other parameters are investigated, whereas no instrumental stirring, such as vortexing or ultrasonics, is required because the solvent (IALP) is formed in situ. The organic cation and anion used are ethylhexyloxypropylammonium and dodecyl sulfate, respectively. The developed in situ IALP microextraction method for phase separation without centrifugation is tested using the thymol blue dye and several endocrine disruptors. The tested endocrine disruptors (bisphenol A, 17β-estradiol, 17α-ethinylestradiol, and estrone) are analyzed via high-performance liquid chromatography/fluorescence detection, with respective detection limits of 0.02, 0.02, 0.02, and 0.4 μg L⁻¹, and the corresponding enrichment factor ranging from 47 to 71. This IALP microextraction method can be used to separate and concentrate environmental water samples of different matrices. The employed IALP is fast and easy to use, enables an approximately 100-fold analyte concentration, and has a high affinity for estrogens, thus holding promise for the separation, concentration, and quantitation of diverse trace analytes. Full article

(1) Background: The aim of this study was to investigate the cyclic fatigue behavior of the newly introduced endodontic instrument systems Tia Tornado Blue and Tia Tornado Gold. (2) Methods: The tested rotary instruments were divided according to their type into four groups as follows: Tia Tornado Blue (TTB), Tia Tornado Gold (TTG), Protaper Gold (PTG), and Vortex Blue (VB). The cyclic fatigue resistance of fifteen instruments of each group, totaling 60, was tested. Each instrument was rotated under continuous motion inside an artificial canal at simulated body temperature at the speed recommended by the manufacturer until fracture. The time to fracture was recorded, and the number of cycles to fracture (NCF) was calculated for each instrument. Additionally, the fractured segment length was calculated, and scanning electron microscopic (SEM) images were captured of the fractured surfaces. (3) Results: Statistical analysis revealed that the VB significantly had the highest NCF followed by the PTG, TTG, and TTB (p < 0.05). The lengths of the fractured segments were found to be similar among the tested instrument, which ranged from 4.42 to 4.86 mm (p > 0.05). SEM images exhibited the typical features of cyclic fatigue. (4) Conclusions: The newly introduced instruments, TTG and TTB, exhibited a significantly lower resistance to cyclic fatigue compared to the PTG and VB rotary instruments. Full article

Energy converters based on vortex-induced vibrations (VIV) have shown great potential for harvesting energy from low-velocity flows, which constitute a significant portion of ocean energy. However, solid-solid triboelectric nanogenerators (TENG) are not wear-resistant in corrosive environments. Therefore, to effectively harvest ocean energy over the long term, a novel solid-liquid triboelectric nanogenerator based on vortex-induced resonance (VIV-SL-TENG) is presented. The energy is harvested through the resonance between VIV of a cylinder and the relative motions of solid-liquid friction pairs inside the cylinder. The factors that affect the output performance of the system, including the liquid mass ratio and the deflection angle of the friction plates, are studied and optimized by establishing mathematical models and conducting computational fluid dynamics simulations. Furthermore, an experimental platform for the VIV-SL-TENG system is constructed to test and validate the performance of the harvester under different conditions. The experiments demonstrate that the energy harvester can successfully convert VIV energy into electrical energy and reach maximum output voltage in the resonance state. As a new type of energy harvester, the presented design shows a promising potential in the field of ‘blue energy’ harvesting. Full article

Chlorophyll-a (Chl-a) change details derived from HY-1C/D images in the waters of the Zhoushan archipelago were analyzed. A new Chl-a inverse model was built based on the relationship between the in situ Chl-a and the combination of red, blue and green bands of the coastal zone imager (CZI). Chl-a as well as fishery resources were analyzed. The results showed the following. (1) The Chl-a concentration in the waters of the Zhoushan archipelago was mainly in the range of 0.5~6 μg/L. High Chl-a area distributed in the west side of the study area, with a value of 3.5~5.5 μg/L. The Chl-a concentration in the east side of the study area was relatively lower, with a value of 0.5~2 μg/L. Chl-a around the islands was higher than that in the area far away from the islands. In addition, Chl-a concentration increased obviously downstream of the island. (2) The spawning ground of many fish in the waters of the Zhoushan archipelago was abundant, and its spatial-temporal variation was consistent with the change of Chl-a. (3) The islands interacted with the current, inducing upwelling upstream and vortex streets downstream. The complex hydrodynamic environment promoted a vertical exchange of water bodies, thereby resulting in an increase in suspended sediment concentration, nutrients, Chl-a and attracting fish. Full article

This study aimed to compare three endodontic rotary systems. The new Genius Proflex (25/0.04), Vortex Blue (25/0.04), and TruNatomy (26/0.04v) instruments (n = 41 per group) were analyzed regarding design, metallurgy, and mechanical performance, while shaping ability (untouched canal walls, volume of removed dentin and hard tissue debris) was tested in 36 anatomically matched root canals of mandibular molars. The results were compared using one-way ANOVA, post hoc Tukey, and Kruskal–Wallis tests, with a significance level set at 5%. All instruments showed symmetrical cross-sections, with asymmetrical blades, no radial lands, no major defects, and almost equiatomic nickel–titanium ratios. Differences were noted in the number of blades, helical angles, cross-sectional design, and tip geometry. The Genius Proflex and the TruNatomy instruments had the highest and lowest R-phase start and finish temperatures, as well as the highest and lowest time and cycles to fracture (p < 0.05), respectively. The TruNatomy had the highest flexibility (p < 0.05), while no differences were observed between the Genius Proflex and the Vortex Blue (p > 0.05). No differences among tested systems were observed regarding the maximum torque, angle of rotation prior to fracture, and shaping ability (p > 0.05). The instruments showed similarities and differences in their design, metallurgy, and mechanical properties. However, their shaping ability was similar, without any clinically significant errors. Understanding these characteristics may help clinicians to make decisions regarding which instrument to choose for a particular clinical situation. Full article

An in-depth evaluation of the mechanical and metallurgical properties of NiTi instruments is fundamental to assess their performance and to compare recently introduced instrument with widespread ones. According to this, since there are no data on this topic, the aim of the study was to mechanically and metallurgically evaluate an instrument recently introduced into the market (ZenFlex (ZF)), by comparing it with two well-known instruments with similar characteristics: Vortex Blue (VB) and EdgeSequel Sapphire (EES). According to this, 195 instruments were selected: 65 ZF, 65 VB and 65 EES. Each group was divided in subgroups according to the mechanical tests (i.e., cyclic fatigue resistance, torsional resistance and bending ability; (n = 20)) and the metallurgical test (differential scanning calorimetry (n = 5)). A scanning electron microscopy was performed to verify the causes of fracture after mechanical tests (cyclic fatigue and torsional tests). According to results, VB showed the highest flexibility and cyclic fatigue resistance in comparison to the other instruments, with a statistically significant difference (p < 0.05). Regarding torsional resistance, EES showed the lowest value of torque at fracture, with a statistically significant difference, whilst the comparison between ZF and VB showed no statistically significant difference (p > 0.05). DSC analysis pointed out that VB had the highest austenite start and finish temperatures, followed by ESS and then ZF. ESS sample showed the highest martensite start and finish temperatures followed by VB and ZF. Considering the results, it can be concluded that VB showed the best mechanical performance during static tests in comparison to ESS and ZF. This is fundamentally due to the interaction of parameters such as instrument design and heat-treatments that are able to enhance its mechanical performance. Full article

The topological charge of an optical vortex is a quantity rather stable against phase distortions, for example, turbulence. This makes the topological charge attractive for optical communications, but for many structured beams it is unknown. Here, we derive the topological charge (TC) of a coaxial superposition of spatially coherent Laguerre–Gaussian beams with different colors, each beam with its own wavelength and its own TC. It turns out that the TC of such a superposition equals the TC of the LG beam with a longer wavelength, regardless of the weight coefficient of this beam in the superposition and regardless of its TC. It is interesting that the instantaneous TC of such a superposition is conserved on propagation, whereas the time-averaged intensity distribution of the colored optical vortex changes its gamut; if, in the near field, the colors of the light rings arrange along the radius according to their TCs in the superposition from lower to greater, then, on space propagation, the colors of the light rings in the cross-section are arranged in reverse order from the greater TC to the lower TC. We also demonstrate that, by choosing appropriate wavelengths (blue, green, and red) in a three-color superposition of single-ringed LG beams, it is possible to generate, at some propagation distance, a time-averaged light ring of the white color. If all the beams in a three-color superposition of single-ringed LG beams have the same TC, then there is a single ring of nearly white light in the initial plane. Then, on propagation in space, light rings of different colors acquire different radii: a smaller ring radius for a shorter wavelength. Full article

Background: The aim of this study was to analyze the influence of NiTi alloy in endodontic rotary instruments on cyclic fatigue resistance. Methods: One hundred and sixty-four (164) sterile endodontic rotary files were selected and distributed into the following study groups: A: 25.08 F2 ProTaper Universal (PTU) (n = 41); B: 25.06 X2 ProTaper Next (PTN) (n = 41); C: 25.08 F2 ProTaper Gold (PTG) (n = 41), and D: 25.06 ProFile Vortex Blue (PVB) (n = 41). A cyclic fatigue device was designed to conduct the static cyclic fatigue tests with stainless steel artificial root canals systems with 250 µm apical diameter, 60° curvature angle, 5 mm radius of curvature, 20 mm length, and 6% (25.06) and 8% taper (25.08). Failure of the endodontic rotary instrument was detected by a single operator through direct observation and was also filmed to allow measurement of the exact time to failure. Results were analyzed using the ANOVA test and Weibull statistical analysis. Results: All pairwise comparisons presented statistically significant differences between the time to failure for the NiTi alloy study groups (p < 0.001), except between the PTN and PVB study groups (p = 0.379). In addition, statistically significant differences between the number of cycles to failure for the NiTi alloy study groups (p < 0.001) were also observed. Conclusions: The NiTi CM-Gold wire alloy of the ProTaper Gold endodontic rotary files resulted in greater resistance to cyclic fatigue than ProFile Vortex Blue, ProTaper Next, and ProTaper Universal endodontic rotary files. Full article

This study determined the antimicrobial efficiency of light-activated disinfection (LAD) and photodynamic therapy (PDT) on polymer-infiltrated ceramic network (PICN) material contaminated with three periodontal bacteria and explored if PDT and LAD cause PICN surface alterations. Sixty PICN discs were contaminated with Tannerella forsythia, Porphyromonas gingivalis, and Treponema denticola and randomly divided into five groups (n = 12 samples/each) according to the treatment groups: Group PDT—PDT (630 ± 10 nm diode laser) with methylene blue; Group DL—808 nm diode laser in contact mode without photosensitizer; Group MB–methylene blue without light application; Group CHX—0.12% chlorhexidine digluconate solution and; Group NT—no treatment. Each disc was then placed in tubes containing phosphate buffered saline (PBS) and vortexed for 30 s to remove the remaining bacteria from the discs. A total of 10× serial dilutions were performed followed by plating of 30 μL of suspension on Brucella agar plates. The colony forming units (CFU) were calculated after 72 h. PICN discs with the attached biofilms were used for confocal microscopy investigation for live/dead bacterial viability. A random single sample from each group was selected to study the bacterial adherence and topographical alterations on PICN discs under scanning electron microscope (SEM). The PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group (p < 0.05). When compared with MB group, the two laser groups were significantly superior (p < 0.05). The MB group did not show significant differences for any bacteria when compared to NT. The bacteria with the CHX group and DL groups appeared dead with few areas of surviving green stained bacteria. The PDT group showed the highest dead cell count (p < 0.05). PDT and DL groups indicate no significant changes on the surface compared to the sterile PICN discs on visual assessment. Photodynamic therapy produced superior periodontal bacteria reduction over the surface of PICN surface. PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group. Both PDT and DL treatment strategies are effective without producing surface alterations on PICN. Full article

Remote sensing of tornado damage can provide valuable observations for post-event surveys and reconstructions. The tornadoes of 3 March 2019 in the southeastern United States are an ideal opportunity to relate high-resolution satellite imagery of damage with estimated wind speeds from post-event surveys, as well as with the Rankine vortex tornado wind field model. Of the spectral metrics tested, the strongest correlations with survey-estimated wind speeds are found using a Normalized Difference Vegetation Index (NDVI, used as a proxy for vegetation health) difference image and a principal components analysis emphasizing differences in red and blue band reflectance. NDVI-differenced values across the width of the EF-4 Beauregard-Smiths Station, Alabama, tornado path resemble the pattern of maximum ground-relative wind speeds across the width of the Rankine vortex model. Maximum damage sampled using these techniques occurred within 130 m of the tornado vortex center. The findings presented herein establish the utility of widely accessible Sentinel imagery, which is shown to have sufficient spatial resolution to make inferences about the intensity and dynamics of violent tornadoes occurring in vegetated areas. Full article

Tornadoes remain an active subject of observational and numerical research due to the damage and fatalities they cause worldwide as well as poor understanding of their behavior, such as what processes result in their genesis and what determines their longevity and morphology. A numerical model executed on a supercomputer run at high resolution can serve as a powerful tool for exploring the rapidly evolving tornado-scale features within a simulated storm, but saving large amounts data for meaningful analysis can result in unacceptably slow model performance, an unwieldy amount of saved data, and saved data spread across millions of files. In this paper, a system for efficiently saving and managing hundreds of terabytes of compressed model output is described to support a supercomputer simulation of a tornadic supercell thunderstorm. The challenges of managing a simulation spanning over a quarter-trillion grid volumes across the Blue Waters supercomputer are also described. The simulated supercell produces a long-track EF5 tornado, and the near-tornado environment is described during tornadogenesis, where single upward-growing vortex undergoes several vortex mergers before transitioning into a multiple-vortex tornado. Full article

The flow and flame characteristics of a 15° backward-inclined jet flame in crossflow were investigated in a wind tunnel. The flow structures, flame behaviors, and temperature fields were measured. The jet-to-crossflow momentum flux ratio was less than 7.0. The flow patterns were investigated using photography and Mie-scattering techniques. Meanwhile, the velocity fields were observed using particle image velocimetry techniques, whereas the flame behaviors were studied using photographic techniques. The flame temperatures were probed using a fine-wire R-type thermocouple. Three flame modes were identified: crossflow dominated flames, which were characterized by a blue flame connected to a down-washed yellow recirculation flame; transitional flames identified by a yellow recirculation flame and an elongated yellow tail flame; and detached jet dominated flames denoted by a blue flame base connected to a yellow tail flame. The effect of the flow characteristics on the combustion performance in different flame regimes is presented and discussed. The upwind shear layer of the bent jet exhibited different coherent structures as the jet-to-crossflow momentum flux ratio increased. The transitional flames and detached jet dominated flames presented a double peak temperature distribution in the symmetry plane at x/d = 60. The time-averaged velocity field of the crossflow dominated flames displayed a standing vortex in the wake region, whereas that of the detached jet dominated flames displayed a jet-wake vortex and a wake region source point. Full article