Mean Penetration Depth Research Articles

Comparison of different cementing techniques for cement penetration under tibial component in total knee arthroplasty: a retrospective observational study

PurposeThis study aimed to investigate the differences in cement penetration between cementing techniques in total knee arthroplasty (TKA).Materials and methodsWe retrospectively evaluated knee undergone TKA at our hospital for both preoperative and postoperative computed tomographic (CT) evaluations. Cementing was performed with hand mixing and hand packing (HM group) and with vacuum mixing and cement gun use (VM group). We measured the area under the tibial baseplate (sclerotic and nonsclerotic sides) and compared the mean and maximum depths of cement penetration at each area.ResultsOf the 44 knees evaluated, 20 and 24 knees were in the HM and VM groups, respectively. At the center of the sclerotic side, the mean penetration depths (2.0 ± 0.7 and 2.5 ± 0.7 mm, p = 0.02) and the maximum penetration depths (4.0 ± 0.9 and 5.0 ± 1.6 mm, p = 0.02) were significantly deeper in the VM group than in the HM group. The correlation between preoperative Hounsfield unit values and mean penetration were r = –0.617 (p < 0.01) and –0.373 (p = 0.01) in the HM and VM groups, respectively.ConclusionThe cementing technique of vacuum mixing and using a cement gun allowed for deeper cement penetration compared with the hand mixing and hand packing technique, even in bone sclerotic sites.

Numerical simulation of keyhole-induced pores for TA15 in laser powder bed fusion (L-PBF)

In the complex laser powder bed fusion (L-PBF) process, the occurrence of pores is often triggered when localized temperatures of the materials exceed their boiling point, posing a significant impediment to the overall quality of manufactured parts. In this work, considering the thermophysical properties and latent heat of phase transformation of the material, the formation and evolution of keyholes and pores during the L-PBF single-track processing of TA15 titanium alloy was investigated using X-ray computed tomography (X-CT) and FLOW-3D finite volume analysis software coupled with multiphysics fields. The simulated molten pool characteristics generally agree with the experimental data, including internal pores The results showed that the evolution of keyholes is mainly attributed to surface tension and recoil pressure, the Marangoni flow and surface tension contributed to closed localized cooling regions on the keyhole walls to generate pores. Additionally, the Marangoni flow and buoyancy effects lead to pore motion within the molten pool. Furthermore, the laser energy density is inherently related to the total pore counts and the mean penetration depth of keyholes, respectively. Understanding the underlying physical mechanisms helps to optimize process parameters and reduce pores in L-PBF, ultimately enhancing the quality of the additively manufactured parts.

Predicting the penetration depth and towing resistance of beam trawl fishing gears in sand

Accurate characterization of mechanical perturbations on the seabed is essential for developing models assessing the environmental impacts from physical disturbances. Furthermore, understanding the relationship between (1) seabed resistance and (2) penetration depth, can also facilitate the development of more efficient and less impactful fishing gears. This study examines these two aspects of tickler chain rigged beam trawling via large-scale physical experiments. Three scaled down models (“light,” “medium,” and “heavy” designs) were developed to represent the impacts from typical beam trawl configurations used in the North Sea and were towed at various speeds on a saturated sand bed. Results reveal that increasing the towing speed reduces the mean penetration depth and the steady-state towing resistance of the gears. Smaller scale physical model tests incorporating tickler chains in sand, demonstrate that the towing resistance is significantly influenced by the soil compaction and particle sizes. Moreover, our study offers a simple and efficient method to estimate the penetration depth and towing resistance of prototype beam trawl gears in sand. This approach, along with the associated research, may be valuable for marine scientists assessing trawling impacts and demersal fishing gear designers seeking to optimize efficiency while minimizing seabed disturbance.

Influence of different pre-treatments on the resin infiltration depth into enamel of teeth affected by molar-incisor hypomineralization (MIH)

ObjectivesThis in vitro pilot study aimed to evaluate whether different pre-treatments (demineralization, deproteinization, (chemo-)mechanical reduction of the surface layer) influence the penetration depth of a resin infiltrant into MIH-affected enamel compared to initial carious lesions. MethodsThirty extracted human permanent molars with non-cavitated initial carious lesions (n = 5) or MIH (n = 25) were chosen and randomly assigned to six experimental groups: IC: initial caries; M: MIH; MN: MIH, 5.25% sodium hypochlorite; MM: MIH, microabrasion; MA: MIH, air abrasion; MAN: MIH, air abrasion and 5.25% sodium hypochlorite. A modified indirect dual fluorescence staining method was adopted to assess the penetration depth (PD) of the resin infiltrant and the lesion depth (LD) by confocal laser scanning microscopy (CLSM). Exemplarily, scanning electron microscopic (SEM) images were captured. The relationship between group assignment and penetration/lesion depth was estimated using a linear mixed model incorporating the tooth as random effect (two observations/tooth). The significance level was set at p < 0.05. ResultsFor MIH-affected molars, the mean PD (in µm; median, [minimum-maximum]) were M (178.2 [32.5–748.9]), MN (275.6 [105.3–1131.0]), MM (48.7 [0.0–334.4]), MA (287.7 [239.4–491.7]), and MAN (245.4 [76.1–313.5]). Despite the observed differences in PD between the groups, these could not be statistically verified (Bonferroni, p = 0.322). The percentage penetration was significantly higher for IC than for MIH groups (Bonferroni, p < 0.05). SignificanceCompared to IC, resin infiltration into MIH-affected enamel ist more variable. Different pre-treatments influence the resin penetration into developmentally hypomineralized enamel to a fluctuating level.

Statistics of Bubble Plumes Generated by Breaking Surface Waves

AbstractWe examine the dependence of the penetration depth and fractional surface area (e.g., whitecap coverage) of bubble plumes generated by breaking surface waves on various wind and wave parameters over a wide range of sea state conditions in the North Pacific Ocean, including storms with sustained winds up to 22 m s−1 and significant wave heights up to 10 m. Our observations include arrays of freely drifting SWIFT buoys together with shipboard systems, which enabled concurrent high‐resolution measurements of wind, waves, bubble plumes, and turbulence. We estimate bubble plume penetration depth from echograms extending to depths of more than 30 m in a surface‐following reference frame collected by downward‐looking echosounders integrated onboard the buoys. Our observations indicate that mean and maximum bubble plume penetration depths exceed 10 and 30 m beneath the surface during high winds, respectively, with plume residence times of many wave periods. They also establish strong correlations between bubble plume depths and wind speeds, spectral wave steepness, and whitecap coverage. Interestingly, we observe a robust linear correlation between plume depths, when scaled by the total significant wave height, and the inverse of wave age. However, scaled plume depths exhibit non‐monotonic variations with increasing wind speeds. Additionally, we explore the dependencies of the combined observations on various non‐dimensional predictors used for whitecap coverage estimation. This study provides the first field evidence of a direct relation between bubble plume penetration depth and whitecap coverage, suggesting that the volume of bubble plumes could be estimated by remote sensing.

Assessment of different irrigation techniques on the penetration depth of different sealers into dentinal tubules by confocal laser scanning microscope: An in vitro comparative study.

The effective disinfection of the entire root canal system aids in the penetration of irrigants into the dentinal tubules further improving sealer penetration and achieving a three-dimensional seal in endodontically treated teeth. Various final irrigation techniques can be employed to achieve this goal. Therefore, this study intended to assess and compare the efficacy of three final irrigation techniques on the depth of penetration of two root canal sealers into dentinal tubules using confocal laser scanning microscope (CLSM). Forty-eight single-rooted mandibular premolars were selected and decoronated to a length of 12 mm. All the samples were prepared using ProTaper Gold rotary files and divided into three groups: Group 1 - Conventional syringe irrigation (CSI), Group 2 - passive ultrasonic irrigation (PUI), and Group 3 - Pro-agitator tip system (PATS). Each group was divided into two subgroups: Subgroup A - AH Plus and Subgroup B - GuttaFlow Bioseal (GFB). Then, sealers were mixed with 0.1% rhodamine B dye and the samples were obturated. All the samples were sectioned at 2 mm and 5 mm from the apex and visualized under confocal laser scanning microscope (CLSM) (10×) for maximum mean penetration depth and percentage of sealer penetration. Statistical analysis was done using the independent t-test and one-way analysis of variance test, followed by Tukey's Post hoc analysis. PUI performed better in the apical third, whereas PUI and PATS showed comparable results in the middle third for both depth and percentage of sealer penetration. Among the two sealers, GFB performed better than AH Plus in both the apical and middle third. These values were statistically significant. (P < 0.05). Final irrigation activation with PUI or PATS can significantly improve sealer penetration. The average depth of penetration of GFB both at the middle and apical third of the root was significantly superior to AH Plus.

Comparative Evaluation of Penetrability of Various Bioceramic Sealers into the Tubules of Radicular Dentin

Aim: This study aimed to evaluate the penetration depth and persistence of sealer residues in obturated canals with three different bioceramic sealers using confocal microscopy. Materials and Methods: In total, 60 single-rooted human premolars were selected and decoronated to maintain the working length of 14 mm. The samples were biomechanically prepared and obturated with Protaper Universal GP coated with three different bioceramic sealers, that is, CeraSeal RC, Bio-C and MTA Fillapex. The specimens were divided into three groups ( n = 20) depending on the sealer used. Rhodamine B fluorescent dye was added to the sealers before using them for obturation. The obturated samples were sealed and placed in 100% humidity at 37oC for 7 days. Gutta-percha was removed from all the samples using retreatment files. Each sample was horizontally sectioned into 2 mm thick slices at 3 mm and 5 mm from the apex, which were analysed under a confocal scanning microscope to detect the depth of penetration of sealer into the dentinal tubules. Data were analysed using one-way ANOVA and Tukey’s post hoc tests. Results: Intergroup comparison of penetration depth at 3 mm showed that the mean depth of penetration among CeraSeal samples was found to be significantly more as compared to the other two materials, while, no statistically significant difference was found among Bio-C and MTA Fillapex with the significance level established at 5% ( P &lt; .05). Similarly, an intergroup comparison of penetration depth at 5 mm showed that the mean depth of penetration among CeraSeal samples was found to be significantly more as compared to the other two materials, while, no statistically significant difference was found among Bio-C and MTA Fillapex. CeraSeal RC sealer showed significantly higher depth of penetration than Bio-C and MTA Fillapex. Conclusion: All bioceramic sealers show a significant penetration into the dentinal tubules. However, none of the sealers was completely removed from the tubules following retreatment.

Quality Assessment of the Atmospheric Radio Occultation Profiles from FY-3E/GNOS-II BDS and GPS Measurements

The Fengyun-3E (FY-3E) satellite carrying the advanced Global Navigation Satellite System (GNSS) Radio Occultation Sounder-II (GNOS-II) is already in operation for radio occultation (RO) observation, with the BeiDou Navigation Satellite System (BDS-2 and BDS-3) and Global Positioning System (GPS) signals tracking capability. FY-3E BDS and GPS RO signals tracking capability were first evaluated by comparing their penetration depths, and then the quality of the refractivity, temperature, and specific humidity profiles was analyzed with the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis (ERA5) data. Results show the mean penetration depth of BDS occultations was 1.65 km compared to 1.09 km of GPS occultations. Between 5 and 25 km, the mean refractivity bias of the BDS (GPS) was −0.14% (0.01%) with the mean standard deviation (SD) being 1.11% (1.52%); the mean temperature biases of both were within ±0.1 K, and the mean SD of BDS was 1.1 K compared to 1.2 K for the GPS; BDS/GPS specific humidity bias was within ±0.3 g/kg with corresponding SD being less than 1.3 g/kg. Seasonal deviations of specific humidities were largest in summer and smallest in winter. Latitudinal deviations over the tropics were generally higher than in other areas. Enriched quantity and high accuracy and precision after careful calibration will promote the FY-3E RO profiles as a reliable data source for the RO community.

The effects of chelation on the intratubular penetration depth of mineral trioxide aggregate.

The penetration depth and extent of mineral trioxide aggregate (MTA) crystallisation into dentinal tubules at 2, 4 and 6 weeks after chelation and MTA obturation were investigated. Standardised 12 mm human root specimens (45) were prepared with NiTi rotary files using 4% NaOCl irrigation. They were randomly allocated to three irrigants (n = 15: 4% NaOCl, 15% ethylenediaminetetraacetic acid or Edgemix) and obturated with sodium fluorescein tagged ProRoot MTA. One millimetre thick apical, middle and coronal sections were examined using confocal laser scanning microscopy to determine MTA penetration depth and area. Depths varied from 352 to 1821 μm at 6 weeks depending on section level and were unaffected by chelation. No differences (p > 0.05) were found in mean maximum penetration depth or dentine area (%) between the 3 irrigants at all time intervals. MTA mineralisation penetrated up to 90% of dentinal tubules and can extend to the cementum in roots with patent, non-infected tubules.

Evaluating the effect of different irrigation activation techniques on the dentin tubules penetration of two different root canal sealers by laser scanning confocal microscopy.

The aim of this study is to evaluate the effect of different irrigation activation techniques on the dentin tubules penetration of two different sealers by confocal laser scanning microscope (CLSM). A hundred premolar teeth were used in this study. The root canals were shaped and irrigated with 5% NaOCl and 17% EDTA using the following final irrigation activation techniques in each group; Group1: Conventional Syringe Irrigation (CSI), Group2: Passive Ultrasonic Irrigation (PUI), Group3: Apical Negative Pressure (EndoVac), Group4: Er:YAG laser and Group5: Er,Cr:YSGG laser. Then the teeth were separated two subgroups according to sealers (AH-Plus and Totalfill-BC). Horizontal sections were obtained at 2, 5, 8 mm distance of apex. Images were obtained with CLSM and the penetration areas of sealers were calculated with four different dentin tubule penetration assessment techniques. The data were statistically analyzed with Kruskal Wallis and Mann Whitney U tests. No significant difference was observed between the sealers (p > .05). EndoVac, Er:YAG and Er,Cr:YSGG laser activation groups were observed to have a significantly higher mean penetration depth, penetration percentage and penetration area than the Control group. There was a significant difference between all regions in all penetration parameters (p < .05). While the use of resin or bioceramic-based root canal sealers did not affect dentin tubule penetration, the use of activation techniques positively affect the dentin tubule penetration. The average tubule penetration and penetration area assessment techniques are suitable methods for the investigation of dentinal tubule penetration. It can be stated that the use of resin or bioceramic based root canal sealers does not affect dentin tubule penetration and the use of irrigation activation techniques during removal of the smear layer positively affects dentinal tubule penetration. In addition, it has been determined that the average tubule penetration and penetration area assessment techniques are suitable methods for the investigation of dentinal tubule penetration.

Verification Makhov,s profile for slow positron in Germanium

In this paper the mean penetration depths z0 and Makhov (Implantation) profile I(z,E) were evaluated for low energies positrons(1.5-30/keV)by using a distribution function of Valkealahti - Nieminen for Germanium for different thicknesses:0.2, 0.4,0.8,1.2,1.4,1.6 μm. The obtained results reveals that the values of Makhov,s profile decreased exponentialy with increasing the positron energy and profile depths increasing linearly with increasing the incident energy. The shape of the Makhov,s profile reflects the shape of the energy spectrum of the positrons, which indicates the annihilation of positrons inside the material where its wavefunction is delocalized.

Study on spray characteristics of fan nozzle in an afterburner environment

In this study, an innovative fan nozzle was designed to improve the ignition and cross-flame performance of the integrated afterburner and the spray characteristics of the fan nozzle in an afterburner environment were studied. A laser particle analyzer and a high-speed camera were used to study the impact of pump pressure and inlet air parameters on Sauter mean diameter (SMD) distribution, penetration depth and atomization angle. The results showed that the spatial fuel distribution was a complex three-dimensional (3D) fuel field, which included three regions: upwind, core, and leeward areas. The SMD decreased as the pump pressure increased, and the SMD increased with the increase temperature. The penetration depth in the cross air was divided into internal and external penetration; the internal and external penetration depths increased firstly and then tended to be stable as the pressure. The internal and external penetration depths decreased as cross air velocity; the increase in temperature and pressure of cross air could make the internal and external penetration depth decrease. The cross air parameters and pump pressure were very important parameters. The atomization angle increased as the pump pressure and the atomization angle decreased as cross air velocity. The atomization angle decreases as the cross air temperature slightly. The results showed that fan nozzles were more suitable for ignition and cross flame in the cavity of the afterburner than the direct injection nozzles.

An Improved Forest Height Model Using L-Band Single-Baseline Polarimetric InSAR Data for Various Forest Densities

Forest density affects the inversion of forest height by influencing the penetration and attenuation of synthetic aperture radar (SAR) signals. Traditional forest height inversion methods often fail in low-density forest areas. Based on L-band single-baseline polarimetric SAR interferometry (PolInSAR) simulation data and the BioSAR 2008 data, we proposed a forest height optimization model at the stand scale suitable for various forest densities. This optimization model took into account shortcomings of the three-stage inversion method by employing height errors to represent the mean penetration depth and SINC inversion method. The relationships between forest density and extinction coefficient, penetration depth, phase, and magnitude were also discussed. In the simulated data, the inversion height established by the optimization method was 17.35 m, while the RMSE value was 3.01 m when the forest density was 100 stems/ha. This addressed the drawbacks of the conventional techniques including failing at low forest density. In the real data, the maximum RMSE of the optimization method was 2.17 m as the stand density increased from 628.66 stems/ha to 1330.54 stems/ha, showing the effectiveness and robustness of the optimization model in overcoming the influence of stand density on the inversion process in realistic scenarios. This study overcame the stand density restriction on L-band single baseline PolInSAR data for forest height estimation and offered a reference for algorithm selection and optimization. The technique is expected to be extended from the stand scale to a larger area for forest ecosystem monitoring and management.

Experimental study on the effect of plasma excitation on the atomization characteristics of aviation kerosene transverse jet

In order to explore the critical technology of plasma application to assist fuel atomization, a jet discharge plasma excitation atomization device was independently designed. And the test of fuel atomization characteristics were carried out. The effects of Ar volumetric flow and peak voltage on Sauter mean diameter (SMD) and penetration depth were investigated. The experimental results show that the introduction of plasma can significantly improve atomization characteristics. The introduction of plasma has significantly improved the atomization characteristics, and the SMD is reduced by 6.31%–31.91%. Plasma-assisted regulation can be achieved by changing the peak voltage and Ar volumetric flow. Ar jet plasma excitation inhibits the penetration of single-hole fuel jets in lateral airflow. The regulation of the longitudinal upper and lower boundaries of the single-hole fuel jet can be achieved by changing the peak voltage and Ar volumetric flow. Compared with the traditional atomization device, the new plasma excitation atomization device can produce a better atomization effect. The better the atomization effect, the more thoroughly the fuel particles can be mixed with the air, which can not only considerably shorten the combustion time, but also the more complete the combustion. In addition, it can promote energy saving and emission reduction and prolong the engine’s life. In general, the new plasma atomization device provides a new idea for the future direction of atomization.

The Effect of Primary Root Canal Treatment on Dentinal Tubule Penetration of Calcium Silicate–based Sealers during Endodontic Retreatment

IntroductionThe aim of this study was to evaluate the effect of previous root canal treatment on dentinal tubule penetration of calcium silicate–based sealers during endodontic retreatment and to compare 2 different (commonly used and modified) tubule penetration depth measurement techniques. MethodsThe crowns of mandibular premolar teeth were removed, and root canals were prepared (ProTaper Universal; Dentsply Sirona, York, PA) and obturated using AH Plus (AH; Dentsply DeTrey, Konstanz, Germany), MTA Fillapex (MTAF; Angelus, Londrina, Brazil), and WellRoot ST (WRST; Vericom, Gyeonggi-do, South Korea); 0.1% red Rhod-2 dye (Chemodex, St Gallen, Switzerland) was added to the sealers. After storage for 3 weeks (37°C, 100% humid), the following sealer combination subgroups were created (the sealer used during the primary root canal treatment/the sealer used during the retreatment, n = 8): AH/AH, AH/MTAF, and AH/WRST; MTAF/AH, MTAF/MTAF, and MTAF/WRST; and WRST/AH, WRST/MTAF, and WRST/WRST. Green Fluo-3 dye (0.1%) was added to the sealers during retreatment. Sealer penetration depths were measured at 8 points and averaged, and the ratio of the retreatment sealer to the initial sealer was recorded as the mean tubule penetration depth ratio in the first technique, whereas the percentage of the circumferential penetration area ratios of the retreatment and initial sealers was calculated in the second technique. Statistical analyses were performed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests. ResultsThe mean penetration depth of AH and MTFA was found to be higher at the coronal third region in the control groups (P < .05). Both methods showed a significant difference among the groups at the coronal and median regions (P < .05). The AH/WRST, MTAH/AH, MTAF/MTAF, MTAF/WRSTS, and WRST/WRST groups showed deeper tubule penetration (first technique, P = .01). Both techniques showed that the penetration depth of the sealers was the same at the apical region (P > .05), whereas a difference was found among the techniques at the coronal and median regions. The sealers used in the previous root canal treatment limited the penetration depth of the sealers used during the retreatment process (P < .05). When MTAF was used as the initial sealer, the penetration depth of the second sealer did not change, whereas if WRST was the initial sealer, the penetration depth of the sealers at the median and apical regions is negatively affected during the retreatment process (P < .05). ConclusionsPrevious root canal treatment affects the penetration depth of calcium silicate–based sealers. The use of AH Plus and MTA Fillapex during the retreatment process showed an advantage. Both measurement techniques showed similar performances at the apical region, whereas the results varied at the coronal and midcoronal regions; therefore, a more stable sealer penetration measurement technique is still necessary.

Bipolar Radiofrequency Ablation Does Not Result in Full-Thickness Articular Cartilage Penetration: An Ex Vivo Bovine Investigation

PurposeTo evaluate the depth of penetration of manufacturer-recommended bipolar radiofrequency (BRF) output in healthy hyaline cartilage.MethodsTwo matched knees from a bovine specimen were harvested for immediate testing. BRF probes were used to treat the articular cartilage in a hydrated noncontact technique employing a 1-mm spacer on patellar, condylar, and trochlear surfaces. Two manufacturer-recommended ablate power settings were evaluated to analyze the effect of varying power outputs on the depth of penetration. Surfaces were randomized and treated with BRF ablate setting 3 (AB-3), 4 (AB-4), or left untreated as a control (12 grids each). Slices were extracted from treatment zones and subjected to fluorescein diacetate and propidium iodide viability stains and analyzed with confocal light microscopy. A general linear model was used to determine whether variables such as ablation setting, cartilage location, and side significantly influenced depth of penetration (DoP) and cartilage thickness (Minitab 19, Chicago, IL). When significance was noted (P < .05), a post hoc-Tukey test was used to investigate specific differences.ResultsAB-3 had a 50.9% lower mean DoP than AB-4 (P = .006). The mean DoP was 237.9 ± 140.6 μm for AB-3 and 484.1 ± 267.0 μm for AB-4. Median DoP values were 243.2 ± 149.5 μm for AB-3, 51.2% lower than the 498.4 ± 286.0 μm for AB-4. The mean maximum DoP for AB-3 was 302.4 ± 167.8 μm, 50.6% lower than AB-4 value of 611.6 ± 299.1 μm. Analysis of the cartilage thickness confirmed there was no difference in overall cartilage thickness used for AB-3 versus AB-4 testing (P = .953).ConclusionsThe RF probe ablate power setting AB-3 demonstrated significantly less articular cartilage depth of penetration than the AB-4 setting in a healthy bovine model.Clinical RelevanceDebridement of chondral lesions with plasma BRF is of clinical interest. The presented study adds basic science information for those considering performing this technique.

Zonal and vertical transports of Fukushima-derived radiocesium in the subarctic gyre of the North Pacific until 2014

The Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident in March 2011 resulted in serious radiocesium contamination of the North Pacific Ocean. Most of the radiocesium was dissolved in seawater and transported by surface currents and subduction of mode waters. Within several years after the accident, a high-concentration water plume of the FNPP1-derived radiocesium at the sea surface had been transported from Japan to the North American continent across the subarctic gyre of the North Pacific Ocean. We measured vertical profiles of dissolved radiocesium along the nominal 47°N zonal line across the North Pacific subarctic gyre twice, in summer 2012 and summer 2014. Using these data and published data, we quantitatively discussed the zonal and vertical transports of the water plume until 2014. The FNPP1-derived radiocesium remained in the surface layer shallower than 200 m, which is the approximate winter mixed-layer depth in the western subarctic gyre. The mean penetration depth did not change between 2012 and 2014. The highest concentration was observed at 180°W in 2012 and at 151°W in 2014, which suggests that the zonal transport speed of the water plume in the eastern subarctic gyre was about 3.8 cm s−1. By combining the data from the zonal line in 2014 and a nominal 152°W meridional line in 2015, we elucidated the three-dimensional size of the high-concentration water plume in summer 2014. The total inventory of the FNPP1-derived radiocesium in the subarctic North Pacific Ocean, decay-corrected to the accident date, was estimated to be 12.0 ± 2.4 PBq.

Radiocarbon in the Atmosphere and Seawater in the South China Sea: Flux, Inventory and Air‐Sea CO2 Exchange Rate Tracing

AbstractΔ14C values of the atmosphere and seawater dissolved inorganic carbon (DIC) were measured during a cruise in the South China Sea (SCS) in September 2015, in order to determine the 14C flux and bomb 14C‐based air‐sea CO2 exchange rates for this region. The background atmospheric Δ14C value (13.8 ± 5.0‰) for the SCS during that period was lower than that (35.4 ± 3.4‰) of surface seawater (5 m) DIC, and a net transfer of 14C from the sea to the atmosphere (7.4 ± 5.0 × 1011 atoms m−2 yr−1) was determined at the wind speed of 5.2 ± 1.7 m s−1. Seawater DIC Δ14C profiles showed the highest value (37.9 ± 3.7‰) at a depth of 100 m, a rapid decrease below that depth to −220.3 ± 3.2‰ at 1,500 m, and nearly constant values below 1,500 m. The average mean penetration depth of bomb 14C was 585.5 ± 99.2 m, and a value of 8.2 ± 1.0 × 109 atoms cm−2 was obtained for the bomb 14C inventory in this region. Based on this inventory, a long‐term (1954–2015) average air‐sea CO2 exchange rate of 20.2 ± 2.8 mol m−2 yr−1 was traced for the SCS. Combined with the pCO2 measurements in this region, a net CO2 flux rate of 0.54 ± 0.08 mol m−2 yr−1 was yielded for the SCS, which is comparable to the cruise measured flux (0.44 ± 0.62 mol m−2 yr−1) obtained from a synthesis study (Li et al., 2020, https://doi.org/10.1016/j.pocean.2020.102272). Our study highlights the importance of continued atmospheric and seawater 14C observations on determining the air‐sea flux in this region.

Cavitation erosion improvement following TIG surface-remelting of gray cast iron

The paper analyses the effect of the surface microstructure effects on the cavitation erosion following rapid re-melting and solidification of gray cast iron parts with lamellar graphite and perlitic matrix. The heat source used was the electric arc generated between the tungsten electrode (via the TIG process) and the gray cast iron part. The local melting of the surface was performed at different linear energy values (El = 3420–5400 J/cm) varying the current between 60 A and 90 A, at a constant voltage of 9.5–10 V. The results showed an increase of the surface hardness from 192 to 198 HV5 to 700–740 HV5 and an improvement of the cavitation erosion resistance, the mean penetration depth of the erosion decreasing by 2.4 times, and the erosion rate by 3.56 times.Optical and scanning electron microscope were used to characterize the microstructure and to identify the phases in the re-melted area. The results showed that the melting of the surface led to an almost complete dissolution of the graphite lamella; the fine microstructure after re-solidification was composed of dendrites of transformed austenite embedded in ledeburite, consisting of transformed austenite and cementite Fe3C. Austenite dendrites have a preferential orientation and martensite needles are formed inside some of them.

Comparison of the efficacy of Icon resin infiltration and Clinpro XT varnish on remineralization of white spot lesions: An in-vitro study.

OBJECTIVE:To compare the efficacy of Icon resin infiltration and Clinpro XT varnish on remineralization of white spot lesions using a polarized light microscope (PLM).MATERIALS & METHODS:Artificial white spot lesions were created on a sample of 40 extracted human premolar teeth by immersing in a demineralizing solution. All samples were randomly allocated to two groups of 20 each; Group A: Icon resin infiltration and Group B: Clinpro XT varnish. Teeth were sectioned along the buccolingual plane using a diamond disc. Specimens were observed under the PLM (4× magnification) at three deepest measurements and their averages were calculated to obtain the mean penetration depth. The data obtained were analyzed using SPSS software (version 22.0). Independent samples t-test and group statistics were used to compare the two groups. In all statistical tests, the significance level was set at 5% (P < 0.05).RESULTS:Both Icon resin infiltration and Clinpro XT groups showed a statistically significant difference (P = 0.00) in the penetration depth. Icon resin infiltration group showed a significantly higher penetration depth (24.46 μm) compared to the Clinpro XT group (12.34 μm). Group A showed a greater mean penetration depth (17.07 ± 4.35 μm) when compared to group B (7.68 ± 1.81 μm).CONCLUSION:Icon resin infiltration showed a significantly higher penetration depth and is more effective on remineralization of white spot lesions when compared to Clinpro XT varnish.