Weibull Analysis Research Articles

Tensile Examination and Strength Evaluation of Latewood in Japanese Cedar.

With the crisis awareness of global warming and natural disasters, utilization of local wood has drawn increasing attention in achieving the Sustainable Development Goals (SDGs). It is necessary to investigate the deformation and fracture of the structural tissue in wood in order to improve the safety and reliability of wood application. However, deformation and fracture mechanisms of the structural tissue in each annual ring are unknown. The mechanical characteristics of wood are reflected in the properties of earlywood and latewood. In the present study, microstructural observation and tensile tests were conducted to examine the relationship between the mechanical properties and fracture behavior of latewood in the growth direction in Japanese cedar. Brittle fracture behavior of the latewood specimen was confirmed based on the tensile stress–strain curve and features of the fracture surface. Moreover, two fracture modes, tensile fracture and shear fracture, were recognized. Weibull analysis of tensile strength in each fracture mode was performed to evaluate the reliability and utility of brittle latewood. Lastly, two fracture mechanisms were discussed based on the failure observation findings by a scanning electron microscope.

Full mapping tensile bond strength of luting in search for differences due to centripetal curing shrinkage

Objectivestesting if hypothetical transverse centripetal strains due to polymerization contraction of luting materials produce differential alterations in its bonding to luted structures, depending on distances to the center of the luting mass, and if this effect is C-factor related. Two hypotheses were tested: (1) there is a statistically significant decreasing relationship between the bonding strength and the transverse distances to the center of the luting material, and (2) there is a statistically significant difference between bonding strengths among luting spaces with different configuration factors. Methods10 PMMA (15 mm Ø) pairs of cylinders were cemented (Scotchbond Universal adhesive & Relyx Universal, both chemically cured) in a compliant setup under two (20 and 70 N) luting forces forming 2 groups (5 samples each), resulting in different C-factors. Whole samples were sectioned in x and y directions obtaining non-trimmed beams from all along the luting surfaces. Their relative positions in each sample were assessed before separating and categorized (10 categories) according to their distances to the center of the sample. All beams were tested in tension and, because of their uneven bonding areas and to balance its influence, UTS results were transformed into UTSres. First hypothesis was tested trough a linear relationship between UTSres and distances to vertical centers per samples. Second hypothesis was tested using Mann-Whitney U tests to compare UTSres between groups, along all categories. Further Weibull analysis was applied. ResultsANOVA’s p of the regression UTSres – categories were statistically significant for all samples in group 70 N and for all except one in group 20 N: first hypothesis is partially maintained. Although Mann-Whitney tests p comparing UTSres of both groups for all categories but the first were statistically significant this hypothesis was maintained relying in Weibull analysis. Significance: bonded attachment of cemented materials decreases from centers to outbounds in plane, extensive surfaces, and this decrease is C-factor related.

Surface Treatment and Cementation of Lithium Silicate Ceramics Containing ZrO2.

To evaluate the effect of different surface treatments on the shear bond strength (SBS) of lithium silicate (LS) and lithium disilicate (LD) ceramics, after thermocycling. For SBS test, 72 ceramic blocks (18×14×2 mm) were made (24 blocks from each ceramic material): VITA Suprinity (LSS), Celtra Duo (LSC), and Lithium disilicate (LD). The blocks were polished with sandpaper of increasing grit (#280, #400, #800, and #1200) and embedded in chemically activated acrylic resin. Afterwards, they were randomly divided into 12 groups (6 blocks per group) according to: "Ceramic" (LD, LSC, and LSS) and "Surface treatment" (HFS: hydrofluoric acid + silane; MEP: Monobond Etch & Prime/Ivoclar). From each treated surface ceramic block, four dual-curing resin cement cylinders (RelyX U200, 3M Oral Care) were prepared using a Tygon tube (Ø=3 mm and h=2 mm) and light cured for 40 seconds (1000 mW/cm2) (N=288/n=24). All specimens were submitted to thermocycling (10,000 cycles, 5°C and 55°C, 30 seconds) and then to SBS test at a crosshead speed of 1 mm/min using a 50-kgf load cell. Forty-five additional blocks were made for roughness and SEM analysis. Failure mode was also performed. The data (MPa) were statistically analyzed by oneway analysis of variance (ANOVA), Tukey test (5%), and Weibull analysis. The Ra was analyzed by Kruskal-Wallis and Dunn Test (5%). The other variables were analyzed qualitatively. ANOVA revealed that "surface treatment" was significant for all ceramic materials (p<0.05). The LD-HFS (18.66±3.49), LSC-HFS (16.81±2.62), and LSS-HFS (16.33±3.08) groups had significantly higher SBS than the LD-MEP (7.00±4.2), LSCMEP (14.12±3.51), and LSS-MEP (13.87±2.52) groups. Complete adhesive failures at the cement-dentin interface were more frequent. Weibull modulus was superior for the LD-HFS (6.22), LSC-HFS (8.8), and LSS-HFS (7.4) groups. HF followed by silanization is the most suitable surface treatment for the cementation of LS and LD glass ceramics.

Degradation of Dental Methacrylate-Based Composites in Simulated Clinical Immersion Media.

The selection of restorative materials with regard to the longevity and durability of a restoration is of crucial importance for daily dental practice and requires that the degradation of the material in the oral environment can be assessed. The aim of this study was to investigate the extent to which the mechanical properties of four (Esthet X, Ceram X, Filtek Supreme XT, and Filtek Supreme XT flow) resin-based composites (RBCs) alter during storage in saliva substitutes (artificial saliva) for 24 h and 28 days and in the context of simulated, more aggressive clinical conditions, including cycles exposure to de- and remineralization, alcohol, or salivary enzymes. For this purpose, flexural strength and modulus were determined in a three-point bending test (n = 20) followed by Weibull analysis, while quasi-static behavior was evaluated by instrumented indentation techniques. Degradation occurred in all RBCs and all aging protocols and was quantifiable at both macroscopic and microscopic levels. The postulated stabilizing effect on degradation through the incorporation of urethane-based co-monomers into the organic matrix or a higher filler loading is refuted. Even though modern RBCs show high clinical survival rates, biodegradation remains an issue that needs to be addressed.

Assessment of onshore wind energy potential under temperate continental climate conditions

Using the Weibull distribution function, the study presents a statistical evaluation of wind characteristics and onshore wind power potential under temperate continental climate conditions. Wind energy projects are more expensive to install than conventional energy sources, but they have lower operating and maintenance costs (zero costs for fuel). Because the initial investment is so large, conducting as precise and reliable feasibility studies as possible is critical because they play a significant role in lowering the cost of energy production. As a result, wind speed measurements are critical for conducting accurate feasibility studies. The availability and accuracy of weather data are critical for determining wind potential at a specific location. Wind speed is an important factor to consider when analyzing the wind speed distribution function. The monthly and yearly values of Weibull parameters, and wind power density at the analyzed location, were estimated using wind speed data. The yearly value of the k parameter for the Weibull analysis was 1.153, and for the c parameter was 5.602, respectively. Also, the yearly average wind speed was found to be greater than the maximum wind speed. Another important conclusion is that the maximum energy-producing wind speed, rather than the average or most frequent wind speed, has the greatest influence on wind potential. The final outcome of this study indicate that the location analyzed is adequate for the exploitation of wind energy.

Effectiveness of surface treatment on bond strength of ceramic brackets to two types of CAD/CAM-prepared nanohybrid composites.

The aim of this study was to assess the influence of surface treatment on the shear bond strength of two different adhesive-coated orthodontic ceramic brackets to computer-aided design/computer-aided manufacturing (CAD/CAM) nanohybrid composite. A total of 120specimens (10 mm × 10 mm × 3 mm) were prepared from each type of CAD/CAM block (Grandio [GR], VOCO Cuxhaven, Germany; Lava Ultimate [LU], 3M ESPE, St. Paul, MN, USA). For each type of CAD/CAM block, the plates were divided into four groups based on the applied surface treatment: hydrofluoric acid (HF), grinding bur (GB), silica coating with CoJet system (CS), and titanium tetrafluoride (TiF4) 2 wt/v%. Maxillary central incisors of adhesive-coated ceramic orthodontic brackets (APC Flash-free Clarity Advanced Ceramic, 3M Unitek, Monrovia, CA, USA) were bonded using Transbond XT Primer (3M Unitek, Monrovia, CA, USA). Shear bond strength was conducted, and the modes of failure were assessed utilizing the adhesive remnant index. Surface roughness and topography of treated CAD/CAM were evaluated. Data were statistically analyzed using two-way analysis of variance (ANOVA) and Tukey's test. The Weibull analysis was conducted on shear bond strength data. Surface treatment with 2% TiF4 wt/v revealed significantly higher bond strength (GR, 14.51 ± 2.57 MPa; LU, 11.19 ± 2.17 MPa) than other groups for both types of CAD/CAM restorative materials (p < 0.05). Adhesive failures were the predominant mode of failure. Surface treatment with CS revealed higher surface roughness than other groups (p < 0.05). Surface treatment with 2% TiF4 wt/v enhanced the adhesion between orthodontic ceramic brackets to GR and LU CAD/CAM composite restorative materials. GR CAD/CAM nanohybrid composite had higher bond strength than LU to ceramic orthodontic brackets.

Mechanical evaluation of WC-Co materials with varying microstructures

Tungsten carbide‑cobalt materials are useful in a variety of extreme applications due to a desirable blend of properties, yet the technology has not significantly changed since their initial development in the 1920s. The mechanical properties of this class of materials is highly dependent on two variables, the size of the tungsten carbide grains, and the amount of binder phase present in the final body. In this study, the amount of binder phase is isolated across three commercial materials from the same manufacturer with three different grain sizes to investigate the effect on mechanical properties. The mechanical properties investigated are indentation hardness, flexure and tensile strength, as well as fracture toughness. In general, an increase in hardness and tensile strength with decreasing grain size was observed, while the fracture toughness showed the opposite trend with toughness increasing with increasing grain size. The flexure strength results did not show a correlation to grain size. Fractographic analysis identified the dominant strength-limiting flaw for each sample, which largely were in the form of porosity. Other flaws types, such as inclusions from the milling process, clusters of large grains, and machining cracks from the surface finishing process, were also identified. Weibull analysis was performed and deemed appropriate for analysis of these materials, but strength-size scaling was not conducted due to the variability in the strength-limiting feature between the different specimen geometries.

3D-printed resins for provisional dental restorations: Comparison of mechanical and biological properties.

To characterize the mechanical and biological properties of three commercially available resins, which are currently used for provisional restorations and to compare them to an experimental resin intended for definitive fixed dental prostheses. Three commercially available resins: Crowntec (CT, Saremco), Temporary C&B (FL, Formlabs), C&B MFH (ND, Nextdent), and the experimental resin: Permanent Bridge (PB, Saremco) were printed and subjected to biaxial flexural strength test, finite element analysis, Weibull analysis, scanning electron microscopy, cell proliferation, immunohistochemistry and cytotoxicity assays. Samples from CT, PB, and ND were provided directly from the manufacturers ensuring ideal workflow. FL was printed using the workflow as recommended by the manufacturer, using a Formlabs 2 printer and their post-processing units Form Wash and Form Cure. From the tested resins, PB yielded the best overall results in terms of mechanical properties. Cell proliferation and cytotoxicity did not show any significant differences among materials. PB showed higher values for probability of survival predictions (35%) when subjected to 250 MPa loads, whereas the other materials did not reach 10%. Despite mechanical differences between the evaluated materials, the outcomes suggest that 3D printed provisional resins may be used in clinical settings, following the manufacturers indications. New materials intended for long-term use, such as the PB resin, yielded higher mechanical properties compared to the other materials. Alternative printing and post-processing methods have not yet been evaluated and should be avoided until further literature is available. 3D printed resins for provisional restorations have become popular with the emergence of new technologies. In this study, we evaluated three different commercially available resins for provisional restorations and one new experimental resin. The results from this study indicate that commercially available resins could be used in clinical settings under certain conditions and limited periods of time. Following the manufacturers protocols is of paramount importance to not compromise these properties.

Time until onset of acute kidney injury by combination therapy with "Triple Whammy" drugs obtained from Japanese Adverse Drug Event Report database.

Acute kidney injury (AKI) associated with “Triple Whammy” drug therapy consisting of renin-angiotensin system inhibitors, diuretics, and nonsteroidal anti-inflammatory drugs (NSAIDs) has been reported. There have been no reports investigating “Triple Whammy” drug therapy and the time to AKI onset using adverse drug events report databases. The aim of this study was to determine the relationship between the time to AKI onset and treatment with “Triple Whammy” drug therapy. We analyzed AKI cases registered in the Japanese Adverse Drug Event Report database. The data were analyzed using the Kaplan–Meier approach, generalized Wilcoxon tests, and Weibull distribution. AKI was reported in 18,415 cases, of which 7,466 cases used Triple Whammy drugs. All combinations of Triple Whammy drugs were associated with significantly higher odds ratios for reporting AKI. In Weibull analysis, AKI onset was early for most combination patterns of Triple Whammy drugs. The Kaplan–Meier approach showed that the treatment duration to AKI onset was much shorter in cases using NSAIDs; median onsets, 8 days for triple combination, 7 days for NSAIDs added to renin-angiotensin system inhibitors, 9 days for NSAIDs added to diuretics, 6 days for diuretics added to NSAIDs, and 9 days for NSAIDs alone. AKI associated with Triple Whammy drugs is likely to occur in the early stages of treatment, especially with concomitant NSAIDs. Patients should be monitored for the occurrence of AKI within the first 2 weeks.

Weibull Analysis Applications in Unexpected Electrical Breakdown of Ion Thruster

The unexpected electrical breakdown (UEBD) of ion thruster is a critical problem. It directly affects the reliability and performance of the ion thruster. The basic UEBD characteristics and Weibull theory are introduced. The self-consistency and applicability of Weibull analysis for UEBD study are discussed. The UEBD period is a proper characteristic variable for Weibull analysis. The approaches to study the factors affecting the UEBD period are presented: (i) distinguishing the effect of coupled factors with the shape parameter of a mixed Weibull distribution, and (ii) studying the effect of a single factor with its respective parameters of the Weibull distribution. The factors discussed include electric field strength, grid material, and ion density. Further aspects to investigate involving the coupling of these factors and mechanisms are prospected.

Study on the Mechanical Property of High‐Performance Silicon Carbide Fiber

The mechanical behavior of silicon carbide (SiC) fiber used in ceramic matrix composites is valuable to permit the prediction of composite behavior and tailoring of composite properties. Herein, single‐fiber tensile tests of different SiC fibers are carried out and Weibull analysis is implemented to characterize its tensile property. To better understand its mechanical behavior, the surface and tensile fracture morphology of different fibers are observed by scanning electron microscopy (SEM) and the fiber elemental composition along the radial distribution is qualitatively analyzed by energy dispersive spectrometer (EDS). Also, the crystallinity and crystallite size of the fiber are analyzed by X‐ray diffraction (XRD). The results show that the tensile strength of SiC fiber conforms to the Weibull distribution, and its mechanical property is influenced by the surface morphology, elemental composition, crystallinity, and crystallite size.

Biaxial Flexural Strength of Different Monolithic Zirconia upon Post-Sintering Processes.

Objective Different post-sintering processes are expected to be a reason for alteration in the strength of zirconia. This study evaluated the effect of post-sintering processes on the flexural strength of different types of monolithic zirconia. Materials and Methods A total of 120 classical- (Cz) and high-translucent (Hz) monolithic zirconia discs (1.2 mm thickness and 14 mm in Ø) were prepared, sintered, and randomly divided into four groups to be surface-treated with (1) as-glazed (AG); (2) finished and polished (FP); (3) finished, polished, and overglazed (FPOG); and (4) finished, polished, and heat-treated (FPHT) technique ( n = 15). Biaxial flexural strength (σ) was determined on a piston-on-three ball in a universal testing machine at a speed of 0.5 mm/min. Statistical Analysis Analysis of variance, and post hoc Bonferroni multiple comparisons were determined for significant differences ( α = 0.05 ). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic strength (σ 0 ). The microstructures were examined with a scanning electron microscope and X-ray diffraction. Results The mean ± standard deviation value of σ (MPa), m, and σ 0 were 1,626.43 ± 184.38, 9.51, and 1,709.79 for CzAG; 1,734.98 ± 136.15, 12.83, and 1,799.17 for CzFP; 1,636.92 ± 130.11, 14.66, and 1,697.63 for CzFPOG; and 1,590.78 ± 161.74, 10.13, and 1,663.82 for CzFPHT; 643.30 ± 118.59, 5.59, and 695.55 for HzAG; 671.52 ± 96.77, 3.28, and 782.61 for HzFP; 556.33 ± 122.85, 4.76, and 607.01 for HzFPOG; and 598.36 ± 57.96, 11.22, and 624.89 for HzFPHT. The σ was significantly affected by the post-sintering process and type of zirconia ( p < 0.05), but not by their interactions ( p > 0.05). The Cz indicated a significantly higher σ than Hz. The FP process significantly enhanced σ more than other treatment procedures. Conclusion Post-sintering processes enabled an alteration in σ of zirconia. FP enhanced σ, while FPOG and FPHT resulted in a reduction of σ. Glazing tends to induce defects at the glazing interface, while heat treatment induces a phase change to tetragonal, both resulted in reducing σ. Finishing and polishing for both Cz and Hz monolithic zirconia is recommended, while overglazed or heat-treated is not suggested.

How long should urologists observe patients with prostate cancer after radical prostatectomy? Weibull analysis.

There is no recommended observation time for patients who have undergone radical prostatectomy for prostate cancer. This study was undertaken to determine the postoperative observation time by investigating the hazard rate for prostate-specific antigen failure and other-cause death using Weibull analysis. We included 612 patients who underwent laparoscopic radical prostatectomy for localized prostate cancer between June 2002 and December 2017. Risk classification was categorized by the D'Amico risk classification, and the patients were divided into three age groups: <60, 60-69 and ≥70 years. The hazard rates at each point were derived using Weibull analysis. The optimal observation time after laparoscopic radical prostatectomy was determined as the intersection point at which the hazard rate of other-cause death overtakes the hazard rate of prostate-specific antigen failure. In all groups classified by age, the hazard rate of other-cause deaths increased over time. In contrast, the hazard rate of prostate-specific antigen failure decreased gradually. The ≥70 years age group showed the highest hazard rate. The hazard rate of prostate-specific antigen failure was highest in the high-risk group. The patients aged ≥70 and 60-69 years in the low-risk group were recommended 6 years 6 months and 14 years 8 months, respectively, for observation. The remaining patients were recommended >25 years of postsurgical observation. The observation time after laparoscopic radical prostatectomy could be estimated by comparing the estimated hazard rates of prostate-specific antigen failure and other-cause death based on Weibull analysis. Urologists should pay attention to age and risk classifications for optimal postoperative observation.

Weibull parameter based probability distribution for predicting creep life of power plant materials: A non-destructive approach

The knowledge of remaining useful life and the probability of failure at any point of time in the life cycle of any power plant component is an important information for the plant operators to take preventive action. This paper focuses on life data evaluation of creep-exposed power plant material based on statistical probability distribution through Weibull analysis. The probability distribution was obtained considering the change in non-linear ultrasonic (NLU) parameter measured in P92 steel at different creep test conditions. The material was creep tested at 650⁰C for three different applied stresses. The NLU parameter (β), which indicates the extent of damage, is the ratio of the amplitude of the fundamental frequency of the transmitted signal to the square of the amplitude of the second harmonic of a sinusoidal wave propagated into the material. The two-parameter based Weibull distribution function was adopted for evaluating the cumulative distribution function and failure rate. A sudden increase in NLU parameter was observed at ∼ 80% of creep damage followed by a drop in its value indicating the specimen failure. With increase in applied stress, failure rate increase was also observed. Microstructural observations revealed that with creep progress, the growth and coarsening of precipitates, micro crack formation and their coalescence were the major cause for increase in failure rate. Therefore, application of this technique can be useful for evaluating the creep life and probability of failure of any plant component in a non-invasive way.

Comparison of Shear Bond Strength of a Newly Introduced Primer with Conventional Primer Using Two Types of Brackets Bonded to Different Surfaces: An In Vitro Study

Background Increasing prevalence of adult orthodontics necessitates improvement in bonding techniques to different intraoral surfaces enamel composite amalgam porcelain. Research focusing on newer materials minimizing bond failures is important as replacing loose brackets is inefficient time-consuming and costly.Objective To compare the shear bond strength SBS and adhesive remnants achieved with the new Assure Plus AP primer versus conventional Transbond XT TXT primer for bonding metalceramic brackets to three different surfaces tooth enamel composite and porcelain-fused-to-metal PFM ceramic.Methods This in vitro study included 40 samples each of extracted teeth Group-1 composite restorations Group-2 and PFM crowns Group-3 mounted on acrylic blocks onto which metal Category-M or ceramic Category-C brackets were bonded using TXT Subgroup-A or AP primer Subgroup-B 10 samples in each class. Their SBS and Adhesive Remnant Index ARI were compared between and within the groups using ANOVA Tukeyrsquos post hoc analysis and Weibull analysis. The level of significance was set at p lt0.05.Results The two primers showed no significant differences in mean SBS within Groups-1 and 2 and in mean ARI within any group p gt0.05. Group-3 showed higher mean SBS with AP primer than with TXT primer BCgtBMgtACgtAM p lt0.001. Failure probability was also lower with AP than with TXT primer.Conclusion AP primer showed significantly greater SBS than TXT primer when used for bonding brackets to PFM crowns. AP primer also showed lower failure probability than TXT primer on all three surfaces tooth enamel composite PFM ceramic.

20 - Zirconia Strength Degradation Post Air-Abrasion of Veneering and Cementation Surfaces

This study evaluated how the flexural strength of a zirconia-based ceramic (Y-TZP) was affected by air abrasion with 30 μm SiO on both zirconia surfaces: the cementation surface, and the veneering surface. Translucent Y-TZP ceramic bars, for four-point bend testing, were prepared and divided considering the compressive (surface treatment for cementation) and tensile surfaces (surface treatment for veneering). Sandblasting was performed or not for each compressive and tensile surfaces. The specimens from all experimental conditions were analysed by SEM. All specimens were tested in four-point bending. Data were statistically analysed using one-way ANOVA and Post Hoc tests (α= 0.05). A Weibull analysis was used to analyse the strength reliability. According to the results of this investigation, the flexural strength was significantly affected by sandblasting on both surfaces: for veneering (P < 0.001) and for cementation (P < 0.001). Sandblasting the veneering surface, to improve bonding of the veneer to Y-TZP, negatively impacted strength reliability. Sandblasting the cementation surface decreased the flexural strength while increasing the strength reliability.

Comparative evaluation of three nanofilled resin-based dental composites: Cytotoxicity, surface roughness, and flexural properties

The clinical performance of dental composite restoration and its overall success are the result of physical, mechanical, and biological properties of the filling materials. The present study aimed to evaluate surface roughness, flexural properties, and cytotoxicity of two nanohybrids, namely, MI Gracefil and Herculite Ultra, and one nanoceramic dental resin composite DiamondLite. The surface roughness was assessed in two different grinding conditions. Flexural properties were measured by, the three-point bending test and the specimens’ fractured surface was analyzed by scanning electron microscopy. Weibull analysis was performed on the flexural strength data to determine the composites’ reliability. The cytotoxicity test was conducted on MC3T3-E1 cells by the MTS assay. The results showed that grinding conditions had a significant effect on all nanocomposites' surface roughness ( p &lt; .05). Herculite Ultra had a significantly higher flexural strength (125.8 MPa) and flexural modulus (9.8 GPa) as compared to other two nanocomposites ( p &lt; .05). Further, cytotoxicity results indicated that DiamondLite had the lowest cell viability during the incubation period ( p &lt; .05). The current study, therefore, concluded that the evaluated nanocomposites showed satisfactory surface roughness. Herculite Ultra flexural properties and Weibull modulus results make it a reliable choice for direct restorations. The cell viability results also showed that all three nanocomposites had moderate cytotoxicity, making them acceptable for direct application in the mouth.

Effects of Hydrothermal Treatment on the Phase Transformation, Surface Roughness, and Mechanical Properties of Monolithic Translucent Zirconia.

This study aimed to investigate the effects of hydrothermal treatment on four types of monolithic, translucent, yttria-stabilized, tetragonal zirconia polycrystals (Y-TZPs). Two commercially available Y-TZP brands-SuperfectZir High Translucency (Aidite Technology Co, China) and Katana HT (Kuraray Noritake Dental, Japan) were assessed. For each brand of Y-TZP, materials of four coloring types, including noncolored (NC), colored by staining (CS), precolored (PC), and multilayered (ML) specimens were investigated after hydrothermal aging in an autoclave at 134°C/0.2 MPa for 0 (control group), 5, 10, and 20 hours. The tetragonal-to-monoclinic phase transformation, surface roughness, flexural strength, and structural reliability (Weibull analysis) were measured and statistically analyzed (α=0.05). The subsurface microstructure was analyzed with scanning electron microscopy. The group ML exhibited the lowest flexural strength and Weibull characteristic strength among the four coloring types (p<0.05). Slight increases in the monoclinic phase volume, flexural strength, and Weibull characteristic strength were observed after hydrothermal aging (pall<0.05). Regardless of coloring type, no significant effects of aging on the Weibull modulus or surface roughness were found for the tested materials. Compared with the Katana HT cross-sections, the SuperfectZir High Translucency cross-sections exhibited a similar but thicker transformation zone. The coloring procedure and material type were found to affect the mechanical properties and aging resistance of translucent monolithic Y-TZP ceramics. Regardless of the aging time, the surface roughness of the tested Y-TZP ceramics remained unchanged.

Bonding properties of third-generation zirconia CAD-CAM blocks for monolithic restorations to composite and resin-modified glass-ionomer cements.

To compare the interfacial fracture toughness (IFT) of two MDP-based composite cements and a resin-modified glass-ionomer cement (RMGIC) with third-generation zirconia CAD-CAM restorations using two different airborne-particle abrasion (AB) pressures. Blocks were cut into prisms (n=60), split and sintered to the desired equilateral half prisms. Half-prisms were divided into two groups for AB at 0.5 or 2.5 bar with 50 µm Al2O3 particles. Each group was then further divided into 3 subgroups, and half-prisms were bonded to their counterparts with Panavia V5 (V5), Panavia Self Adhesive Cement Plus (SA), or RMGIC Fuji Plus (n=10/group). The IFT was determined using the Notchless Triangular Prism test in a water bath at 36°C after thermocycling (10,000 cycles). Surface roughness and SEM analyses were performed for representative zirconia samples after AB, and composite cements were tested for flexural strength and wettability. SA (2.5 bar) showed a significantly higher IFT. The 3 other groups with SA and V5 showed no significant difference in their IFT values regardless of the AB pressure (1-way ANOVA). Weibull analysis of SA was higher than V5. All RMGIC samples debonded while thermocycling, and were, therefore, not included in the statistical analysis. Surface roughness increased with increasing AB pressure, and both cements showed similar flexural strength values and good wettability. Contrary to RMGIC, composite cements show high performance with zirconia after AB. Increasing AB pressure enhances the micromechanical retention of composite cement. Future perspectives should include study of the effect of AB pressure on zirconia surface properties.

Selected engineering properties of palmyrah (Borassus flabellifer) leaf base

Natural fibres are attracting a lot of attention these days, from industrial applications and basic research, to producing eco-friendly goods. The engineering characteristics of the palmyrah leaf base (Borassus flabellifer) were assessed in this study. The test specimen’s were prepared as per the ASTM standards. The average length of the palmyrah leaf base was around 532±0.72 mm, with 22.74±0.23 mm thickness, 472.6±3.23 g density and volume of 0.893±0.027 g cm3 and 173.14±5.393 cm3. The mechanical properties were obtained by tensile test, impact test, flexural test, and shore-D hardness test. Tensile strength was observed to be 8.77 MPa, percentage of elongation was 40 per cent and the flexural strength 147±2.44 MPa. Significant hardness and lower impact strength confirms the viscoelastic nature of the palmyrah leaf base. The data obtained was analysed statistically using Weibull analysis. The palmyrah leaf base properties obtained will be useful for palm related researchers and industrialists to calculate design consideration for fibre extraction machines and developing fibre related products.